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4125 lines
119 KiB
4125 lines
119 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* INET An implementation of the TCP/IP protocol suite for the LINUX |
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* operating system. INET is implemented using the BSD Socket |
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* interface as the means of communication with the user level. |
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* |
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* Implementation of the Transmission Control Protocol(TCP). |
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* |
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* Authors: Ross Biro |
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* Fred N. van Kempen, <[email protected]> |
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* Mark Evans, <[email protected]> |
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* Corey Minyard <[email protected]> |
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* Florian La Roche, <[email protected]> |
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* Charles Hedrick, <[email protected]> |
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* Linus Torvalds, <[email protected]> |
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* Alan Cox, <[email protected]> |
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* Matthew Dillon, <[email protected]> |
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* Arnt Gulbrandsen, <[email protected]> |
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* Jorge Cwik, <[email protected]> |
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*/ |
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|
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/* |
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* Changes: Pedro Roque : Retransmit queue handled by TCP. |
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* : Fragmentation on mtu decrease |
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* : Segment collapse on retransmit |
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* : AF independence |
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* |
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* Linus Torvalds : send_delayed_ack |
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* David S. Miller : Charge memory using the right skb |
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* during syn/ack processing. |
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* David S. Miller : Output engine completely rewritten. |
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* Andrea Arcangeli: SYNACK carry ts_recent in tsecr. |
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* Cacophonix Gaul : draft-minshall-nagle-01 |
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* J Hadi Salim : ECN support |
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* |
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*/ |
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|
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#define pr_fmt(fmt) "TCP: " fmt |
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|
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#include <net/tcp.h> |
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#include <net/mptcp.h> |
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|
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#include <linux/compiler.h> |
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#include <linux/gfp.h> |
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#include <linux/module.h> |
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#include <linux/static_key.h> |
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#include <trace/events/tcp.h> |
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/* Refresh clocks of a TCP socket, |
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* ensuring monotically increasing values. |
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*/ |
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void tcp_mstamp_refresh(struct tcp_sock *tp) |
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{ |
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u64 val = tcp_clock_ns(); |
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|
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tp->tcp_clock_cache = val; |
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tp->tcp_mstamp = div_u64(val, NSEC_PER_USEC); |
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} |
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static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, |
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int push_one, gfp_t gfp); |
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|
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/* Account for new data that has been sent to the network. */ |
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static void tcp_event_new_data_sent(struct sock *sk, struct sk_buff *skb) |
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{ |
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struct inet_connection_sock *icsk = inet_csk(sk); |
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struct tcp_sock *tp = tcp_sk(sk); |
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unsigned int prior_packets = tp->packets_out; |
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WRITE_ONCE(tp->snd_nxt, TCP_SKB_CB(skb)->end_seq); |
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__skb_unlink(skb, &sk->sk_write_queue); |
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tcp_rbtree_insert(&sk->tcp_rtx_queue, skb); |
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if (tp->highest_sack == NULL) |
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tp->highest_sack = skb; |
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tp->packets_out += tcp_skb_pcount(skb); |
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if (!prior_packets || icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) |
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tcp_rearm_rto(sk); |
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NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT, |
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tcp_skb_pcount(skb)); |
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} |
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/* SND.NXT, if window was not shrunk or the amount of shrunk was less than one |
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* window scaling factor due to loss of precision. |
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* If window has been shrunk, what should we make? It is not clear at all. |
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* Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( |
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* Anything in between SND.UNA...SND.UNA+SND.WND also can be already |
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* invalid. OK, let's make this for now: |
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*/ |
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static inline __u32 tcp_acceptable_seq(const struct sock *sk) |
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{ |
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const struct tcp_sock *tp = tcp_sk(sk); |
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|
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if (!before(tcp_wnd_end(tp), tp->snd_nxt) || |
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(tp->rx_opt.wscale_ok && |
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((tp->snd_nxt - tcp_wnd_end(tp)) < (1 << tp->rx_opt.rcv_wscale)))) |
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return tp->snd_nxt; |
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else |
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return tcp_wnd_end(tp); |
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} |
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|
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/* Calculate mss to advertise in SYN segment. |
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* RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: |
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* |
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* 1. It is independent of path mtu. |
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* 2. Ideally, it is maximal possible segment size i.e. 65535-40. |
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* 3. For IPv4 it is reasonable to calculate it from maximal MTU of |
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* attached devices, because some buggy hosts are confused by |
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* large MSS. |
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* 4. We do not make 3, we advertise MSS, calculated from first |
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* hop device mtu, but allow to raise it to ip_rt_min_advmss. |
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* This may be overridden via information stored in routing table. |
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* 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, |
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* probably even Jumbo". |
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*/ |
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static __u16 tcp_advertise_mss(struct sock *sk) |
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{ |
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struct tcp_sock *tp = tcp_sk(sk); |
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const struct dst_entry *dst = __sk_dst_get(sk); |
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int mss = tp->advmss; |
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if (dst) { |
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unsigned int metric = dst_metric_advmss(dst); |
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if (metric < mss) { |
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mss = metric; |
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tp->advmss = mss; |
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} |
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} |
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return (__u16)mss; |
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} |
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/* RFC2861. Reset CWND after idle period longer RTO to "restart window". |
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* This is the first part of cwnd validation mechanism. |
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*/ |
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void tcp_cwnd_restart(struct sock *sk, s32 delta) |
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{ |
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struct tcp_sock *tp = tcp_sk(sk); |
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u32 restart_cwnd = tcp_init_cwnd(tp, __sk_dst_get(sk)); |
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u32 cwnd = tp->snd_cwnd; |
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tcp_ca_event(sk, CA_EVENT_CWND_RESTART); |
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tp->snd_ssthresh = tcp_current_ssthresh(sk); |
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restart_cwnd = min(restart_cwnd, cwnd); |
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while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) |
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cwnd >>= 1; |
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tp->snd_cwnd = max(cwnd, restart_cwnd); |
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tp->snd_cwnd_stamp = tcp_jiffies32; |
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tp->snd_cwnd_used = 0; |
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} |
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/* Congestion state accounting after a packet has been sent. */ |
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static void tcp_event_data_sent(struct tcp_sock *tp, |
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struct sock *sk) |
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{ |
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struct inet_connection_sock *icsk = inet_csk(sk); |
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const u32 now = tcp_jiffies32; |
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if (tcp_packets_in_flight(tp) == 0) |
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tcp_ca_event(sk, CA_EVENT_TX_START); |
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/* If this is the first data packet sent in response to the |
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* previous received data, |
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* and it is a reply for ato after last received packet, |
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* increase pingpong count. |
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*/ |
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if (before(tp->lsndtime, icsk->icsk_ack.lrcvtime) && |
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(u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) |
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inet_csk_inc_pingpong_cnt(sk); |
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tp->lsndtime = now; |
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} |
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|
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/* Account for an ACK we sent. */ |
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static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts, |
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u32 rcv_nxt) |
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{ |
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struct tcp_sock *tp = tcp_sk(sk); |
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|
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if (unlikely(tp->compressed_ack)) { |
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NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPACKCOMPRESSED, |
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tp->compressed_ack); |
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tp->compressed_ack = 0; |
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if (hrtimer_try_to_cancel(&tp->compressed_ack_timer) == 1) |
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__sock_put(sk); |
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} |
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if (unlikely(rcv_nxt != tp->rcv_nxt)) |
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return; /* Special ACK sent by DCTCP to reflect ECN */ |
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tcp_dec_quickack_mode(sk, pkts); |
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inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); |
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} |
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/* Determine a window scaling and initial window to offer. |
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* Based on the assumption that the given amount of space |
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* will be offered. Store the results in the tp structure. |
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* NOTE: for smooth operation initial space offering should |
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* be a multiple of mss if possible. We assume here that mss >= 1. |
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* This MUST be enforced by all callers. |
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*/ |
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void tcp_select_initial_window(const struct sock *sk, int __space, __u32 mss, |
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__u32 *rcv_wnd, __u32 *window_clamp, |
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int wscale_ok, __u8 *rcv_wscale, |
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__u32 init_rcv_wnd) |
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{ |
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unsigned int space = (__space < 0 ? 0 : __space); |
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|
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/* If no clamp set the clamp to the max possible scaled window */ |
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if (*window_clamp == 0) |
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(*window_clamp) = (U16_MAX << TCP_MAX_WSCALE); |
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space = min(*window_clamp, space); |
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/* Quantize space offering to a multiple of mss if possible. */ |
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if (space > mss) |
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space = rounddown(space, mss); |
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|
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/* NOTE: offering an initial window larger than 32767 |
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* will break some buggy TCP stacks. If the admin tells us |
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* it is likely we could be speaking with such a buggy stack |
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* we will truncate our initial window offering to 32K-1 |
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* unless the remote has sent us a window scaling option, |
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* which we interpret as a sign the remote TCP is not |
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* misinterpreting the window field as a signed quantity. |
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*/ |
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if (sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows) |
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(*rcv_wnd) = min(space, MAX_TCP_WINDOW); |
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else |
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(*rcv_wnd) = min_t(u32, space, U16_MAX); |
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if (init_rcv_wnd) |
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*rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); |
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*rcv_wscale = 0; |
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if (wscale_ok) { |
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/* Set window scaling on max possible window */ |
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space = max_t(u32, space, sock_net(sk)->ipv4.sysctl_tcp_rmem[2]); |
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space = max_t(u32, space, sysctl_rmem_max); |
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space = min_t(u32, space, *window_clamp); |
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*rcv_wscale = clamp_t(int, ilog2(space) - 15, |
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0, TCP_MAX_WSCALE); |
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} |
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/* Set the clamp no higher than max representable value */ |
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(*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp); |
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} |
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EXPORT_SYMBOL(tcp_select_initial_window); |
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/* Chose a new window to advertise, update state in tcp_sock for the |
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* socket, and return result with RFC1323 scaling applied. The return |
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* value can be stuffed directly into th->window for an outgoing |
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* frame. |
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*/ |
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static u16 tcp_select_window(struct sock *sk) |
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{ |
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struct tcp_sock *tp = tcp_sk(sk); |
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u32 old_win = tp->rcv_wnd; |
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u32 cur_win = tcp_receive_window(tp); |
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u32 new_win = __tcp_select_window(sk); |
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/* Never shrink the offered window */ |
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if (new_win < cur_win) { |
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/* Danger Will Robinson! |
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* Don't update rcv_wup/rcv_wnd here or else |
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* we will not be able to advertise a zero |
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* window in time. --DaveM |
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* |
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* Relax Will Robinson. |
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*/ |
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if (new_win == 0) |
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NET_INC_STATS(sock_net(sk), |
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LINUX_MIB_TCPWANTZEROWINDOWADV); |
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new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); |
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} |
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tp->rcv_wnd = new_win; |
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tp->rcv_wup = tp->rcv_nxt; |
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|
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/* Make sure we do not exceed the maximum possible |
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* scaled window. |
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*/ |
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if (!tp->rx_opt.rcv_wscale && |
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sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows) |
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new_win = min(new_win, MAX_TCP_WINDOW); |
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else |
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new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); |
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/* RFC1323 scaling applied */ |
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new_win >>= tp->rx_opt.rcv_wscale; |
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/* If we advertise zero window, disable fast path. */ |
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if (new_win == 0) { |
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tp->pred_flags = 0; |
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if (old_win) |
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NET_INC_STATS(sock_net(sk), |
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LINUX_MIB_TCPTOZEROWINDOWADV); |
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} else if (old_win == 0) { |
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NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFROMZEROWINDOWADV); |
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} |
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return new_win; |
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} |
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/* Packet ECN state for a SYN-ACK */ |
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static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb) |
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{ |
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const struct tcp_sock *tp = tcp_sk(sk); |
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TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; |
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if (!(tp->ecn_flags & TCP_ECN_OK)) |
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TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; |
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else if (tcp_ca_needs_ecn(sk) || |
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tcp_bpf_ca_needs_ecn(sk)) |
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INET_ECN_xmit(sk); |
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} |
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|
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/* Packet ECN state for a SYN. */ |
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static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) |
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{ |
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struct tcp_sock *tp = tcp_sk(sk); |
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bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk); |
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bool use_ecn = sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 || |
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tcp_ca_needs_ecn(sk) || bpf_needs_ecn; |
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if (!use_ecn) { |
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const struct dst_entry *dst = __sk_dst_get(sk); |
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|
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if (dst && dst_feature(dst, RTAX_FEATURE_ECN)) |
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use_ecn = true; |
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} |
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tp->ecn_flags = 0; |
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if (use_ecn) { |
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TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; |
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tp->ecn_flags = TCP_ECN_OK; |
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if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn) |
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INET_ECN_xmit(sk); |
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} |
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} |
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|
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static void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb) |
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{ |
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if (sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback) |
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/* tp->ecn_flags are cleared at a later point in time when |
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* SYN ACK is ultimatively being received. |
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*/ |
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TCP_SKB_CB(skb)->tcp_flags &= ~(TCPHDR_ECE | TCPHDR_CWR); |
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} |
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|
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static void |
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tcp_ecn_make_synack(const struct request_sock *req, struct tcphdr *th) |
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{ |
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if (inet_rsk(req)->ecn_ok) |
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th->ece = 1; |
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} |
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|
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/* Set up ECN state for a packet on a ESTABLISHED socket that is about to |
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* be sent. |
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*/ |
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static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, |
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struct tcphdr *th, int tcp_header_len) |
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{ |
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struct tcp_sock *tp = tcp_sk(sk); |
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|
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if (tp->ecn_flags & TCP_ECN_OK) { |
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/* Not-retransmitted data segment: set ECT and inject CWR. */ |
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if (skb->len != tcp_header_len && |
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!before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { |
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INET_ECN_xmit(sk); |
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if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { |
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tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; |
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th->cwr = 1; |
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skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; |
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} |
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} else if (!tcp_ca_needs_ecn(sk)) { |
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/* ACK or retransmitted segment: clear ECT|CE */ |
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INET_ECN_dontxmit(sk); |
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} |
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if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) |
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th->ece = 1; |
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} |
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} |
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|
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/* Constructs common control bits of non-data skb. If SYN/FIN is present, |
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* auto increment end seqno. |
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*/ |
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static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) |
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{ |
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skb->ip_summed = CHECKSUM_PARTIAL; |
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|
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TCP_SKB_CB(skb)->tcp_flags = flags; |
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TCP_SKB_CB(skb)->sacked = 0; |
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|
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tcp_skb_pcount_set(skb, 1); |
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|
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TCP_SKB_CB(skb)->seq = seq; |
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if (flags & (TCPHDR_SYN | TCPHDR_FIN)) |
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seq++; |
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TCP_SKB_CB(skb)->end_seq = seq; |
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} |
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|
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static inline bool tcp_urg_mode(const struct tcp_sock *tp) |
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{ |
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return tp->snd_una != tp->snd_up; |
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} |
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|
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#define OPTION_SACK_ADVERTISE (1 << 0) |
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#define OPTION_TS (1 << 1) |
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#define OPTION_MD5 (1 << 2) |
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#define OPTION_WSCALE (1 << 3) |
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#define OPTION_FAST_OPEN_COOKIE (1 << 8) |
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#define OPTION_SMC (1 << 9) |
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#define OPTION_MPTCP (1 << 10) |
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|
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static void smc_options_write(__be32 *ptr, u16 *options) |
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{ |
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#if IS_ENABLED(CONFIG_SMC) |
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if (static_branch_unlikely(&tcp_have_smc)) { |
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if (unlikely(OPTION_SMC & *options)) { |
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*ptr++ = htonl((TCPOPT_NOP << 24) | |
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(TCPOPT_NOP << 16) | |
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(TCPOPT_EXP << 8) | |
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(TCPOLEN_EXP_SMC_BASE)); |
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*ptr++ = htonl(TCPOPT_SMC_MAGIC); |
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} |
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} |
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#endif |
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} |
|
|
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struct tcp_out_options { |
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u16 options; /* bit field of OPTION_* */ |
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u16 mss; /* 0 to disable */ |
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u8 ws; /* window scale, 0 to disable */ |
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u8 num_sack_blocks; /* number of SACK blocks to include */ |
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u8 hash_size; /* bytes in hash_location */ |
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u8 bpf_opt_len; /* length of BPF hdr option */ |
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__u8 *hash_location; /* temporary pointer, overloaded */ |
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__u32 tsval, tsecr; /* need to include OPTION_TS */ |
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struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ |
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struct mptcp_out_options mptcp; |
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}; |
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|
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static void mptcp_options_write(__be32 *ptr, const struct tcp_sock *tp, |
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struct tcp_out_options *opts) |
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{ |
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#if IS_ENABLED(CONFIG_MPTCP) |
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if (unlikely(OPTION_MPTCP & opts->options)) |
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mptcp_write_options(ptr, tp, &opts->mptcp); |
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#endif |
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} |
|
|
|
#ifdef CONFIG_CGROUP_BPF |
|
static int bpf_skops_write_hdr_opt_arg0(struct sk_buff *skb, |
|
enum tcp_synack_type synack_type) |
|
{ |
|
if (unlikely(!skb)) |
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return BPF_WRITE_HDR_TCP_CURRENT_MSS; |
|
|
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if (unlikely(synack_type == TCP_SYNACK_COOKIE)) |
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return BPF_WRITE_HDR_TCP_SYNACK_COOKIE; |
|
|
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return 0; |
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} |
|
|
|
/* req, syn_skb and synack_type are used when writing synack */ |
|
static void bpf_skops_hdr_opt_len(struct sock *sk, struct sk_buff *skb, |
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struct request_sock *req, |
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struct sk_buff *syn_skb, |
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enum tcp_synack_type synack_type, |
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struct tcp_out_options *opts, |
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unsigned int *remaining) |
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{ |
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struct bpf_sock_ops_kern sock_ops; |
|
int err; |
|
|
|
if (likely(!BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), |
|
BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG)) || |
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!*remaining) |
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return; |
|
|
|
/* *remaining has already been aligned to 4 bytes, so *remaining >= 4 */ |
|
|
|
/* init sock_ops */ |
|
memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); |
|
|
|
sock_ops.op = BPF_SOCK_OPS_HDR_OPT_LEN_CB; |
|
|
|
if (req) { |
|
/* The listen "sk" cannot be passed here because |
|
* it is not locked. It would not make too much |
|
* sense to do bpf_setsockopt(listen_sk) based |
|
* on individual connection request also. |
|
* |
|
* Thus, "req" is passed here and the cgroup-bpf-progs |
|
* of the listen "sk" will be run. |
|
* |
|
* "req" is also used here for fastopen even the "sk" here is |
|
* a fullsock "child" sk. It is to keep the behavior |
|
* consistent between fastopen and non-fastopen on |
|
* the bpf programming side. |
|
*/ |
|
sock_ops.sk = (struct sock *)req; |
|
sock_ops.syn_skb = syn_skb; |
|
} else { |
|
sock_owned_by_me(sk); |
|
|
|
sock_ops.is_fullsock = 1; |
|
sock_ops.sk = sk; |
|
} |
|
|
|
sock_ops.args[0] = bpf_skops_write_hdr_opt_arg0(skb, synack_type); |
|
sock_ops.remaining_opt_len = *remaining; |
|
/* tcp_current_mss() does not pass a skb */ |
|
if (skb) |
|
bpf_skops_init_skb(&sock_ops, skb, 0); |
|
|
|
err = BPF_CGROUP_RUN_PROG_SOCK_OPS_SK(&sock_ops, sk); |
|
|
|
if (err || sock_ops.remaining_opt_len == *remaining) |
|
return; |
|
|
|
opts->bpf_opt_len = *remaining - sock_ops.remaining_opt_len; |
|
/* round up to 4 bytes */ |
|
opts->bpf_opt_len = (opts->bpf_opt_len + 3) & ~3; |
|
|
|
*remaining -= opts->bpf_opt_len; |
|
} |
|
|
|
static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb, |
|
struct request_sock *req, |
|
struct sk_buff *syn_skb, |
|
enum tcp_synack_type synack_type, |
|
struct tcp_out_options *opts) |
|
{ |
|
u8 first_opt_off, nr_written, max_opt_len = opts->bpf_opt_len; |
|
struct bpf_sock_ops_kern sock_ops; |
|
int err; |
|
|
|
if (likely(!max_opt_len)) |
|
return; |
|
|
|
memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); |
|
|
|
sock_ops.op = BPF_SOCK_OPS_WRITE_HDR_OPT_CB; |
|
|
|
if (req) { |
|
sock_ops.sk = (struct sock *)req; |
|
sock_ops.syn_skb = syn_skb; |
|
} else { |
|
sock_owned_by_me(sk); |
|
|
|
sock_ops.is_fullsock = 1; |
|
sock_ops.sk = sk; |
|
} |
|
|
|
sock_ops.args[0] = bpf_skops_write_hdr_opt_arg0(skb, synack_type); |
|
sock_ops.remaining_opt_len = max_opt_len; |
|
first_opt_off = tcp_hdrlen(skb) - max_opt_len; |
|
bpf_skops_init_skb(&sock_ops, skb, first_opt_off); |
|
|
|
err = BPF_CGROUP_RUN_PROG_SOCK_OPS_SK(&sock_ops, sk); |
|
|
|
if (err) |
|
nr_written = 0; |
|
else |
|
nr_written = max_opt_len - sock_ops.remaining_opt_len; |
|
|
|
if (nr_written < max_opt_len) |
|
memset(skb->data + first_opt_off + nr_written, TCPOPT_NOP, |
|
max_opt_len - nr_written); |
|
} |
|
#else |
|
static void bpf_skops_hdr_opt_len(struct sock *sk, struct sk_buff *skb, |
|
struct request_sock *req, |
|
struct sk_buff *syn_skb, |
|
enum tcp_synack_type synack_type, |
|
struct tcp_out_options *opts, |
|
unsigned int *remaining) |
|
{ |
|
} |
|
|
|
static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb, |
|
struct request_sock *req, |
|
struct sk_buff *syn_skb, |
|
enum tcp_synack_type synack_type, |
|
struct tcp_out_options *opts) |
|
{ |
|
} |
|
#endif |
|
|
|
/* Write previously computed TCP options to the packet. |
|
* |
|
* Beware: Something in the Internet is very sensitive to the ordering of |
|
* TCP options, we learned this through the hard way, so be careful here. |
|
* Luckily we can at least blame others for their non-compliance but from |
|
* inter-operability perspective it seems that we're somewhat stuck with |
|
* the ordering which we have been using if we want to keep working with |
|
* those broken things (not that it currently hurts anybody as there isn't |
|
* particular reason why the ordering would need to be changed). |
|
* |
|
* At least SACK_PERM as the first option is known to lead to a disaster |
|
* (but it may well be that other scenarios fail similarly). |
|
*/ |
|
static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, |
|
struct tcp_out_options *opts) |
|
{ |
|
u16 options = opts->options; /* mungable copy */ |
|
|
|
if (unlikely(OPTION_MD5 & options)) { |
|
*ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | |
|
(TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); |
|
/* overload cookie hash location */ |
|
opts->hash_location = (__u8 *)ptr; |
|
ptr += 4; |
|
} |
|
|
|
if (unlikely(opts->mss)) { |
|
*ptr++ = htonl((TCPOPT_MSS << 24) | |
|
(TCPOLEN_MSS << 16) | |
|
opts->mss); |
|
} |
|
|
|
if (likely(OPTION_TS & options)) { |
|
if (unlikely(OPTION_SACK_ADVERTISE & options)) { |
|
*ptr++ = htonl((TCPOPT_SACK_PERM << 24) | |
|
(TCPOLEN_SACK_PERM << 16) | |
|
(TCPOPT_TIMESTAMP << 8) | |
|
TCPOLEN_TIMESTAMP); |
|
options &= ~OPTION_SACK_ADVERTISE; |
|
} else { |
|
*ptr++ = htonl((TCPOPT_NOP << 24) | |
|
(TCPOPT_NOP << 16) | |
|
(TCPOPT_TIMESTAMP << 8) | |
|
TCPOLEN_TIMESTAMP); |
|
} |
|
*ptr++ = htonl(opts->tsval); |
|
*ptr++ = htonl(opts->tsecr); |
|
} |
|
|
|
if (unlikely(OPTION_SACK_ADVERTISE & options)) { |
|
*ptr++ = htonl((TCPOPT_NOP << 24) | |
|
(TCPOPT_NOP << 16) | |
|
(TCPOPT_SACK_PERM << 8) | |
|
TCPOLEN_SACK_PERM); |
|
} |
|
|
|
if (unlikely(OPTION_WSCALE & options)) { |
|
*ptr++ = htonl((TCPOPT_NOP << 24) | |
|
(TCPOPT_WINDOW << 16) | |
|
(TCPOLEN_WINDOW << 8) | |
|
opts->ws); |
|
} |
|
|
|
if (unlikely(opts->num_sack_blocks)) { |
|
struct tcp_sack_block *sp = tp->rx_opt.dsack ? |
|
tp->duplicate_sack : tp->selective_acks; |
|
int this_sack; |
|
|
|
*ptr++ = htonl((TCPOPT_NOP << 24) | |
|
(TCPOPT_NOP << 16) | |
|
(TCPOPT_SACK << 8) | |
|
(TCPOLEN_SACK_BASE + (opts->num_sack_blocks * |
|
TCPOLEN_SACK_PERBLOCK))); |
|
|
|
for (this_sack = 0; this_sack < opts->num_sack_blocks; |
|
++this_sack) { |
|
*ptr++ = htonl(sp[this_sack].start_seq); |
|
*ptr++ = htonl(sp[this_sack].end_seq); |
|
} |
|
|
|
tp->rx_opt.dsack = 0; |
|
} |
|
|
|
if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { |
|
struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; |
|
u8 *p = (u8 *)ptr; |
|
u32 len; /* Fast Open option length */ |
|
|
|
if (foc->exp) { |
|
len = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; |
|
*ptr = htonl((TCPOPT_EXP << 24) | (len << 16) | |
|
TCPOPT_FASTOPEN_MAGIC); |
|
p += TCPOLEN_EXP_FASTOPEN_BASE; |
|
} else { |
|
len = TCPOLEN_FASTOPEN_BASE + foc->len; |
|
*p++ = TCPOPT_FASTOPEN; |
|
*p++ = len; |
|
} |
|
|
|
memcpy(p, foc->val, foc->len); |
|
if ((len & 3) == 2) { |
|
p[foc->len] = TCPOPT_NOP; |
|
p[foc->len + 1] = TCPOPT_NOP; |
|
} |
|
ptr += (len + 3) >> 2; |
|
} |
|
|
|
smc_options_write(ptr, &options); |
|
|
|
mptcp_options_write(ptr, tp, opts); |
|
} |
|
|
|
static void smc_set_option(const struct tcp_sock *tp, |
|
struct tcp_out_options *opts, |
|
unsigned int *remaining) |
|
{ |
|
#if IS_ENABLED(CONFIG_SMC) |
|
if (static_branch_unlikely(&tcp_have_smc)) { |
|
if (tp->syn_smc) { |
|
if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) { |
|
opts->options |= OPTION_SMC; |
|
*remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED; |
|
} |
|
} |
|
} |
|
#endif |
|
} |
|
|
|
static void smc_set_option_cond(const struct tcp_sock *tp, |
|
const struct inet_request_sock *ireq, |
|
struct tcp_out_options *opts, |
|
unsigned int *remaining) |
|
{ |
|
#if IS_ENABLED(CONFIG_SMC) |
|
if (static_branch_unlikely(&tcp_have_smc)) { |
|
if (tp->syn_smc && ireq->smc_ok) { |
|
if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) { |
|
opts->options |= OPTION_SMC; |
|
*remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED; |
|
} |
|
} |
|
} |
|
#endif |
|
} |
|
|
|
static void mptcp_set_option_cond(const struct request_sock *req, |
|
struct tcp_out_options *opts, |
|
unsigned int *remaining) |
|
{ |
|
if (rsk_is_mptcp(req)) { |
|
unsigned int size; |
|
|
|
if (mptcp_synack_options(req, &size, &opts->mptcp)) { |
|
if (*remaining >= size) { |
|
opts->options |= OPTION_MPTCP; |
|
*remaining -= size; |
|
} |
|
} |
|
} |
|
} |
|
|
|
/* Compute TCP options for SYN packets. This is not the final |
|
* network wire format yet. |
|
*/ |
|
static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, |
|
struct tcp_out_options *opts, |
|
struct tcp_md5sig_key **md5) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
unsigned int remaining = MAX_TCP_OPTION_SPACE; |
|
struct tcp_fastopen_request *fastopen = tp->fastopen_req; |
|
|
|
*md5 = NULL; |
|
#ifdef CONFIG_TCP_MD5SIG |
|
if (static_branch_unlikely(&tcp_md5_needed) && |
|
rcu_access_pointer(tp->md5sig_info)) { |
|
*md5 = tp->af_specific->md5_lookup(sk, sk); |
|
if (*md5) { |
|
opts->options |= OPTION_MD5; |
|
remaining -= TCPOLEN_MD5SIG_ALIGNED; |
|
} |
|
} |
|
#endif |
|
|
|
/* We always get an MSS option. The option bytes which will be seen in |
|
* normal data packets should timestamps be used, must be in the MSS |
|
* advertised. But we subtract them from tp->mss_cache so that |
|
* calculations in tcp_sendmsg are simpler etc. So account for this |
|
* fact here if necessary. If we don't do this correctly, as a |
|
* receiver we won't recognize data packets as being full sized when we |
|
* should, and thus we won't abide by the delayed ACK rules correctly. |
|
* SACKs don't matter, we never delay an ACK when we have any of those |
|
* going out. */ |
|
opts->mss = tcp_advertise_mss(sk); |
|
remaining -= TCPOLEN_MSS_ALIGNED; |
|
|
|
if (likely(sock_net(sk)->ipv4.sysctl_tcp_timestamps && !*md5)) { |
|
opts->options |= OPTION_TS; |
|
opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset; |
|
opts->tsecr = tp->rx_opt.ts_recent; |
|
remaining -= TCPOLEN_TSTAMP_ALIGNED; |
|
} |
|
if (likely(sock_net(sk)->ipv4.sysctl_tcp_window_scaling)) { |
|
opts->ws = tp->rx_opt.rcv_wscale; |
|
opts->options |= OPTION_WSCALE; |
|
remaining -= TCPOLEN_WSCALE_ALIGNED; |
|
} |
|
if (likely(sock_net(sk)->ipv4.sysctl_tcp_sack)) { |
|
opts->options |= OPTION_SACK_ADVERTISE; |
|
if (unlikely(!(OPTION_TS & opts->options))) |
|
remaining -= TCPOLEN_SACKPERM_ALIGNED; |
|
} |
|
|
|
if (fastopen && fastopen->cookie.len >= 0) { |
|
u32 need = fastopen->cookie.len; |
|
|
|
need += fastopen->cookie.exp ? TCPOLEN_EXP_FASTOPEN_BASE : |
|
TCPOLEN_FASTOPEN_BASE; |
|
need = (need + 3) & ~3U; /* Align to 32 bits */ |
|
if (remaining >= need) { |
|
opts->options |= OPTION_FAST_OPEN_COOKIE; |
|
opts->fastopen_cookie = &fastopen->cookie; |
|
remaining -= need; |
|
tp->syn_fastopen = 1; |
|
tp->syn_fastopen_exp = fastopen->cookie.exp ? 1 : 0; |
|
} |
|
} |
|
|
|
smc_set_option(tp, opts, &remaining); |
|
|
|
if (sk_is_mptcp(sk)) { |
|
unsigned int size; |
|
|
|
if (mptcp_syn_options(sk, skb, &size, &opts->mptcp)) { |
|
opts->options |= OPTION_MPTCP; |
|
remaining -= size; |
|
} |
|
} |
|
|
|
bpf_skops_hdr_opt_len(sk, skb, NULL, NULL, 0, opts, &remaining); |
|
|
|
return MAX_TCP_OPTION_SPACE - remaining; |
|
} |
|
|
|
/* Set up TCP options for SYN-ACKs. */ |
|
static unsigned int tcp_synack_options(const struct sock *sk, |
|
struct request_sock *req, |
|
unsigned int mss, struct sk_buff *skb, |
|
struct tcp_out_options *opts, |
|
const struct tcp_md5sig_key *md5, |
|
struct tcp_fastopen_cookie *foc, |
|
enum tcp_synack_type synack_type, |
|
struct sk_buff *syn_skb) |
|
{ |
|
struct inet_request_sock *ireq = inet_rsk(req); |
|
unsigned int remaining = MAX_TCP_OPTION_SPACE; |
|
|
|
#ifdef CONFIG_TCP_MD5SIG |
|
if (md5) { |
|
opts->options |= OPTION_MD5; |
|
remaining -= TCPOLEN_MD5SIG_ALIGNED; |
|
|
|
/* We can't fit any SACK blocks in a packet with MD5 + TS |
|
* options. There was discussion about disabling SACK |
|
* rather than TS in order to fit in better with old, |
|
* buggy kernels, but that was deemed to be unnecessary. |
|
*/ |
|
if (synack_type != TCP_SYNACK_COOKIE) |
|
ireq->tstamp_ok &= !ireq->sack_ok; |
|
} |
|
#endif |
|
|
|
/* We always send an MSS option. */ |
|
opts->mss = mss; |
|
remaining -= TCPOLEN_MSS_ALIGNED; |
|
|
|
if (likely(ireq->wscale_ok)) { |
|
opts->ws = ireq->rcv_wscale; |
|
opts->options |= OPTION_WSCALE; |
|
remaining -= TCPOLEN_WSCALE_ALIGNED; |
|
} |
|
if (likely(ireq->tstamp_ok)) { |
|
opts->options |= OPTION_TS; |
|
opts->tsval = tcp_skb_timestamp(skb) + tcp_rsk(req)->ts_off; |
|
opts->tsecr = req->ts_recent; |
|
remaining -= TCPOLEN_TSTAMP_ALIGNED; |
|
} |
|
if (likely(ireq->sack_ok)) { |
|
opts->options |= OPTION_SACK_ADVERTISE; |
|
if (unlikely(!ireq->tstamp_ok)) |
|
remaining -= TCPOLEN_SACKPERM_ALIGNED; |
|
} |
|
if (foc != NULL && foc->len >= 0) { |
|
u32 need = foc->len; |
|
|
|
need += foc->exp ? TCPOLEN_EXP_FASTOPEN_BASE : |
|
TCPOLEN_FASTOPEN_BASE; |
|
need = (need + 3) & ~3U; /* Align to 32 bits */ |
|
if (remaining >= need) { |
|
opts->options |= OPTION_FAST_OPEN_COOKIE; |
|
opts->fastopen_cookie = foc; |
|
remaining -= need; |
|
} |
|
} |
|
|
|
mptcp_set_option_cond(req, opts, &remaining); |
|
|
|
smc_set_option_cond(tcp_sk(sk), ireq, opts, &remaining); |
|
|
|
bpf_skops_hdr_opt_len((struct sock *)sk, skb, req, syn_skb, |
|
synack_type, opts, &remaining); |
|
|
|
return MAX_TCP_OPTION_SPACE - remaining; |
|
} |
|
|
|
/* Compute TCP options for ESTABLISHED sockets. This is not the |
|
* final wire format yet. |
|
*/ |
|
static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, |
|
struct tcp_out_options *opts, |
|
struct tcp_md5sig_key **md5) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
unsigned int size = 0; |
|
unsigned int eff_sacks; |
|
|
|
opts->options = 0; |
|
|
|
*md5 = NULL; |
|
#ifdef CONFIG_TCP_MD5SIG |
|
if (static_branch_unlikely(&tcp_md5_needed) && |
|
rcu_access_pointer(tp->md5sig_info)) { |
|
*md5 = tp->af_specific->md5_lookup(sk, sk); |
|
if (*md5) { |
|
opts->options |= OPTION_MD5; |
|
size += TCPOLEN_MD5SIG_ALIGNED; |
|
} |
|
} |
|
#endif |
|
|
|
if (likely(tp->rx_opt.tstamp_ok)) { |
|
opts->options |= OPTION_TS; |
|
opts->tsval = skb ? tcp_skb_timestamp(skb) + tp->tsoffset : 0; |
|
opts->tsecr = tp->rx_opt.ts_recent; |
|
size += TCPOLEN_TSTAMP_ALIGNED; |
|
} |
|
|
|
/* MPTCP options have precedence over SACK for the limited TCP |
|
* option space because a MPTCP connection would be forced to |
|
* fall back to regular TCP if a required multipath option is |
|
* missing. SACK still gets a chance to use whatever space is |
|
* left. |
|
*/ |
|
if (sk_is_mptcp(sk)) { |
|
unsigned int remaining = MAX_TCP_OPTION_SPACE - size; |
|
unsigned int opt_size = 0; |
|
|
|
if (mptcp_established_options(sk, skb, &opt_size, remaining, |
|
&opts->mptcp)) { |
|
opts->options |= OPTION_MPTCP; |
|
size += opt_size; |
|
} |
|
} |
|
|
|
eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; |
|
if (unlikely(eff_sacks)) { |
|
const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; |
|
if (unlikely(remaining < TCPOLEN_SACK_BASE_ALIGNED + |
|
TCPOLEN_SACK_PERBLOCK)) |
|
return size; |
|
|
|
opts->num_sack_blocks = |
|
min_t(unsigned int, eff_sacks, |
|
(remaining - TCPOLEN_SACK_BASE_ALIGNED) / |
|
TCPOLEN_SACK_PERBLOCK); |
|
|
|
size += TCPOLEN_SACK_BASE_ALIGNED + |
|
opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; |
|
} |
|
|
|
if (unlikely(BPF_SOCK_OPS_TEST_FLAG(tp, |
|
BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG))) { |
|
unsigned int remaining = MAX_TCP_OPTION_SPACE - size; |
|
|
|
bpf_skops_hdr_opt_len(sk, skb, NULL, NULL, 0, opts, &remaining); |
|
|
|
size = MAX_TCP_OPTION_SPACE - remaining; |
|
} |
|
|
|
return size; |
|
} |
|
|
|
|
|
/* TCP SMALL QUEUES (TSQ) |
|
* |
|
* TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) |
|
* to reduce RTT and bufferbloat. |
|
* We do this using a special skb destructor (tcp_wfree). |
|
* |
|
* Its important tcp_wfree() can be replaced by sock_wfree() in the event skb |
|
* needs to be reallocated in a driver. |
|
* The invariant being skb->truesize subtracted from sk->sk_wmem_alloc |
|
* |
|
* Since transmit from skb destructor is forbidden, we use a tasklet |
|
* to process all sockets that eventually need to send more skbs. |
|
* We use one tasklet per cpu, with its own queue of sockets. |
|
*/ |
|
struct tsq_tasklet { |
|
struct tasklet_struct tasklet; |
|
struct list_head head; /* queue of tcp sockets */ |
|
}; |
|
static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); |
|
|
|
static void tcp_tsq_write(struct sock *sk) |
|
{ |
|
if ((1 << sk->sk_state) & |
|
(TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | |
|
TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) { |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
|
|
if (tp->lost_out > tp->retrans_out && |
|
tp->snd_cwnd > tcp_packets_in_flight(tp)) { |
|
tcp_mstamp_refresh(tp); |
|
tcp_xmit_retransmit_queue(sk); |
|
} |
|
|
|
tcp_write_xmit(sk, tcp_current_mss(sk), tp->nonagle, |
|
0, GFP_ATOMIC); |
|
} |
|
} |
|
|
|
static void tcp_tsq_handler(struct sock *sk) |
|
{ |
|
bh_lock_sock(sk); |
|
if (!sock_owned_by_user(sk)) |
|
tcp_tsq_write(sk); |
|
else if (!test_and_set_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags)) |
|
sock_hold(sk); |
|
bh_unlock_sock(sk); |
|
} |
|
/* |
|
* One tasklet per cpu tries to send more skbs. |
|
* We run in tasklet context but need to disable irqs when |
|
* transferring tsq->head because tcp_wfree() might |
|
* interrupt us (non NAPI drivers) |
|
*/ |
|
static void tcp_tasklet_func(struct tasklet_struct *t) |
|
{ |
|
struct tsq_tasklet *tsq = from_tasklet(tsq, t, tasklet); |
|
LIST_HEAD(list); |
|
unsigned long flags; |
|
struct list_head *q, *n; |
|
struct tcp_sock *tp; |
|
struct sock *sk; |
|
|
|
local_irq_save(flags); |
|
list_splice_init(&tsq->head, &list); |
|
local_irq_restore(flags); |
|
|
|
list_for_each_safe(q, n, &list) { |
|
tp = list_entry(q, struct tcp_sock, tsq_node); |
|
list_del(&tp->tsq_node); |
|
|
|
sk = (struct sock *)tp; |
|
smp_mb__before_atomic(); |
|
clear_bit(TSQ_QUEUED, &sk->sk_tsq_flags); |
|
|
|
tcp_tsq_handler(sk); |
|
sk_free(sk); |
|
} |
|
} |
|
|
|
#define TCP_DEFERRED_ALL (TCPF_TSQ_DEFERRED | \ |
|
TCPF_WRITE_TIMER_DEFERRED | \ |
|
TCPF_DELACK_TIMER_DEFERRED | \ |
|
TCPF_MTU_REDUCED_DEFERRED) |
|
/** |
|
* tcp_release_cb - tcp release_sock() callback |
|
* @sk: socket |
|
* |
|
* called from release_sock() to perform protocol dependent |
|
* actions before socket release. |
|
*/ |
|
void tcp_release_cb(struct sock *sk) |
|
{ |
|
unsigned long flags, nflags; |
|
|
|
/* perform an atomic operation only if at least one flag is set */ |
|
do { |
|
flags = sk->sk_tsq_flags; |
|
if (!(flags & TCP_DEFERRED_ALL)) |
|
return; |
|
nflags = flags & ~TCP_DEFERRED_ALL; |
|
} while (cmpxchg(&sk->sk_tsq_flags, flags, nflags) != flags); |
|
|
|
if (flags & TCPF_TSQ_DEFERRED) { |
|
tcp_tsq_write(sk); |
|
__sock_put(sk); |
|
} |
|
/* Here begins the tricky part : |
|
* We are called from release_sock() with : |
|
* 1) BH disabled |
|
* 2) sk_lock.slock spinlock held |
|
* 3) socket owned by us (sk->sk_lock.owned == 1) |
|
* |
|
* But following code is meant to be called from BH handlers, |
|
* so we should keep BH disabled, but early release socket ownership |
|
*/ |
|
sock_release_ownership(sk); |
|
|
|
if (flags & TCPF_WRITE_TIMER_DEFERRED) { |
|
tcp_write_timer_handler(sk); |
|
__sock_put(sk); |
|
} |
|
if (flags & TCPF_DELACK_TIMER_DEFERRED) { |
|
tcp_delack_timer_handler(sk); |
|
__sock_put(sk); |
|
} |
|
if (flags & TCPF_MTU_REDUCED_DEFERRED) { |
|
inet_csk(sk)->icsk_af_ops->mtu_reduced(sk); |
|
__sock_put(sk); |
|
} |
|
} |
|
EXPORT_SYMBOL(tcp_release_cb); |
|
|
|
void __init tcp_tasklet_init(void) |
|
{ |
|
int i; |
|
|
|
for_each_possible_cpu(i) { |
|
struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); |
|
|
|
INIT_LIST_HEAD(&tsq->head); |
|
tasklet_setup(&tsq->tasklet, tcp_tasklet_func); |
|
} |
|
} |
|
|
|
/* |
|
* Write buffer destructor automatically called from kfree_skb. |
|
* We can't xmit new skbs from this context, as we might already |
|
* hold qdisc lock. |
|
*/ |
|
void tcp_wfree(struct sk_buff *skb) |
|
{ |
|
struct sock *sk = skb->sk; |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
unsigned long flags, nval, oval; |
|
|
|
/* Keep one reference on sk_wmem_alloc. |
|
* Will be released by sk_free() from here or tcp_tasklet_func() |
|
*/ |
|
WARN_ON(refcount_sub_and_test(skb->truesize - 1, &sk->sk_wmem_alloc)); |
|
|
|
/* If this softirq is serviced by ksoftirqd, we are likely under stress. |
|
* Wait until our queues (qdisc + devices) are drained. |
|
* This gives : |
|
* - less callbacks to tcp_write_xmit(), reducing stress (batches) |
|
* - chance for incoming ACK (processed by another cpu maybe) |
|
* to migrate this flow (skb->ooo_okay will be eventually set) |
|
*/ |
|
if (refcount_read(&sk->sk_wmem_alloc) >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) |
|
goto out; |
|
|
|
for (oval = READ_ONCE(sk->sk_tsq_flags);; oval = nval) { |
|
struct tsq_tasklet *tsq; |
|
bool empty; |
|
|
|
if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED)) |
|
goto out; |
|
|
|
nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED; |
|
nval = cmpxchg(&sk->sk_tsq_flags, oval, nval); |
|
if (nval != oval) |
|
continue; |
|
|
|
/* queue this socket to tasklet queue */ |
|
local_irq_save(flags); |
|
tsq = this_cpu_ptr(&tsq_tasklet); |
|
empty = list_empty(&tsq->head); |
|
list_add(&tp->tsq_node, &tsq->head); |
|
if (empty) |
|
tasklet_schedule(&tsq->tasklet); |
|
local_irq_restore(flags); |
|
return; |
|
} |
|
out: |
|
sk_free(sk); |
|
} |
|
|
|
/* Note: Called under soft irq. |
|
* We can call TCP stack right away, unless socket is owned by user. |
|
*/ |
|
enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer) |
|
{ |
|
struct tcp_sock *tp = container_of(timer, struct tcp_sock, pacing_timer); |
|
struct sock *sk = (struct sock *)tp; |
|
|
|
tcp_tsq_handler(sk); |
|
sock_put(sk); |
|
|
|
return HRTIMER_NORESTART; |
|
} |
|
|
|
static void tcp_update_skb_after_send(struct sock *sk, struct sk_buff *skb, |
|
u64 prior_wstamp) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
|
|
if (sk->sk_pacing_status != SK_PACING_NONE) { |
|
unsigned long rate = sk->sk_pacing_rate; |
|
|
|
/* Original sch_fq does not pace first 10 MSS |
|
* Note that tp->data_segs_out overflows after 2^32 packets, |
|
* this is a minor annoyance. |
|
*/ |
|
if (rate != ~0UL && rate && tp->data_segs_out >= 10) { |
|
u64 len_ns = div64_ul((u64)skb->len * NSEC_PER_SEC, rate); |
|
u64 credit = tp->tcp_wstamp_ns - prior_wstamp; |
|
|
|
/* take into account OS jitter */ |
|
len_ns -= min_t(u64, len_ns / 2, credit); |
|
tp->tcp_wstamp_ns += len_ns; |
|
} |
|
} |
|
list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); |
|
} |
|
|
|
INDIRECT_CALLABLE_DECLARE(int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)); |
|
INDIRECT_CALLABLE_DECLARE(int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)); |
|
INDIRECT_CALLABLE_DECLARE(void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb)); |
|
|
|
/* This routine actually transmits TCP packets queued in by |
|
* tcp_do_sendmsg(). This is used by both the initial |
|
* transmission and possible later retransmissions. |
|
* All SKB's seen here are completely headerless. It is our |
|
* job to build the TCP header, and pass the packet down to |
|
* IP so it can do the same plus pass the packet off to the |
|
* device. |
|
* |
|
* We are working here with either a clone of the original |
|
* SKB, or a fresh unique copy made by the retransmit engine. |
|
*/ |
|
static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, |
|
int clone_it, gfp_t gfp_mask, u32 rcv_nxt) |
|
{ |
|
const struct inet_connection_sock *icsk = inet_csk(sk); |
|
struct inet_sock *inet; |
|
struct tcp_sock *tp; |
|
struct tcp_skb_cb *tcb; |
|
struct tcp_out_options opts; |
|
unsigned int tcp_options_size, tcp_header_size; |
|
struct sk_buff *oskb = NULL; |
|
struct tcp_md5sig_key *md5; |
|
struct tcphdr *th; |
|
u64 prior_wstamp; |
|
int err; |
|
|
|
BUG_ON(!skb || !tcp_skb_pcount(skb)); |
|
tp = tcp_sk(sk); |
|
prior_wstamp = tp->tcp_wstamp_ns; |
|
tp->tcp_wstamp_ns = max(tp->tcp_wstamp_ns, tp->tcp_clock_cache); |
|
skb->skb_mstamp_ns = tp->tcp_wstamp_ns; |
|
if (clone_it) { |
|
TCP_SKB_CB(skb)->tx.in_flight = TCP_SKB_CB(skb)->end_seq |
|
- tp->snd_una; |
|
oskb = skb; |
|
|
|
tcp_skb_tsorted_save(oskb) { |
|
if (unlikely(skb_cloned(oskb))) |
|
skb = pskb_copy(oskb, gfp_mask); |
|
else |
|
skb = skb_clone(oskb, gfp_mask); |
|
} tcp_skb_tsorted_restore(oskb); |
|
|
|
if (unlikely(!skb)) |
|
return -ENOBUFS; |
|
/* retransmit skbs might have a non zero value in skb->dev |
|
* because skb->dev is aliased with skb->rbnode.rb_left |
|
*/ |
|
skb->dev = NULL; |
|
} |
|
|
|
inet = inet_sk(sk); |
|
tcb = TCP_SKB_CB(skb); |
|
memset(&opts, 0, sizeof(opts)); |
|
|
|
if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) { |
|
tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); |
|
} else { |
|
tcp_options_size = tcp_established_options(sk, skb, &opts, |
|
&md5); |
|
/* Force a PSH flag on all (GSO) packets to expedite GRO flush |
|
* at receiver : This slightly improve GRO performance. |
|
* Note that we do not force the PSH flag for non GSO packets, |
|
* because they might be sent under high congestion events, |
|
* and in this case it is better to delay the delivery of 1-MSS |
|
* packets and thus the corresponding ACK packet that would |
|
* release the following packet. |
|
*/ |
|
if (tcp_skb_pcount(skb) > 1) |
|
tcb->tcp_flags |= TCPHDR_PSH; |
|
} |
|
tcp_header_size = tcp_options_size + sizeof(struct tcphdr); |
|
|
|
/* if no packet is in qdisc/device queue, then allow XPS to select |
|
* another queue. We can be called from tcp_tsq_handler() |
|
* which holds one reference to sk. |
|
* |
|
* TODO: Ideally, in-flight pure ACK packets should not matter here. |
|
* One way to get this would be to set skb->truesize = 2 on them. |
|
*/ |
|
skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1); |
|
|
|
/* If we had to use memory reserve to allocate this skb, |
|
* this might cause drops if packet is looped back : |
|
* Other socket might not have SOCK_MEMALLOC. |
|
* Packets not looped back do not care about pfmemalloc. |
|
*/ |
|
skb->pfmemalloc = 0; |
|
|
|
skb_push(skb, tcp_header_size); |
|
skb_reset_transport_header(skb); |
|
|
|
skb_orphan(skb); |
|
skb->sk = sk; |
|
skb->destructor = skb_is_tcp_pure_ack(skb) ? __sock_wfree : tcp_wfree; |
|
refcount_add(skb->truesize, &sk->sk_wmem_alloc); |
|
|
|
skb_set_dst_pending_confirm(skb, sk->sk_dst_pending_confirm); |
|
|
|
/* Build TCP header and checksum it. */ |
|
th = (struct tcphdr *)skb->data; |
|
th->source = inet->inet_sport; |
|
th->dest = inet->inet_dport; |
|
th->seq = htonl(tcb->seq); |
|
th->ack_seq = htonl(rcv_nxt); |
|
*(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | |
|
tcb->tcp_flags); |
|
|
|
th->check = 0; |
|
th->urg_ptr = 0; |
|
|
|
/* The urg_mode check is necessary during a below snd_una win probe */ |
|
if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { |
|
if (before(tp->snd_up, tcb->seq + 0x10000)) { |
|
th->urg_ptr = htons(tp->snd_up - tcb->seq); |
|
th->urg = 1; |
|
} else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { |
|
th->urg_ptr = htons(0xFFFF); |
|
th->urg = 1; |
|
} |
|
} |
|
|
|
skb_shinfo(skb)->gso_type = sk->sk_gso_type; |
|
if (likely(!(tcb->tcp_flags & TCPHDR_SYN))) { |
|
th->window = htons(tcp_select_window(sk)); |
|
tcp_ecn_send(sk, skb, th, tcp_header_size); |
|
} else { |
|
/* RFC1323: The window in SYN & SYN/ACK segments |
|
* is never scaled. |
|
*/ |
|
th->window = htons(min(tp->rcv_wnd, 65535U)); |
|
} |
|
|
|
tcp_options_write((__be32 *)(th + 1), tp, &opts); |
|
|
|
#ifdef CONFIG_TCP_MD5SIG |
|
/* Calculate the MD5 hash, as we have all we need now */ |
|
if (md5) { |
|
sk_nocaps_add(sk, NETIF_F_GSO_MASK); |
|
tp->af_specific->calc_md5_hash(opts.hash_location, |
|
md5, sk, skb); |
|
} |
|
#endif |
|
|
|
/* BPF prog is the last one writing header option */ |
|
bpf_skops_write_hdr_opt(sk, skb, NULL, NULL, 0, &opts); |
|
|
|
INDIRECT_CALL_INET(icsk->icsk_af_ops->send_check, |
|
tcp_v6_send_check, tcp_v4_send_check, |
|
sk, skb); |
|
|
|
if (likely(tcb->tcp_flags & TCPHDR_ACK)) |
|
tcp_event_ack_sent(sk, tcp_skb_pcount(skb), rcv_nxt); |
|
|
|
if (skb->len != tcp_header_size) { |
|
tcp_event_data_sent(tp, sk); |
|
tp->data_segs_out += tcp_skb_pcount(skb); |
|
tp->bytes_sent += skb->len - tcp_header_size; |
|
} |
|
|
|
if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) |
|
TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, |
|
tcp_skb_pcount(skb)); |
|
|
|
tp->segs_out += tcp_skb_pcount(skb); |
|
skb_set_hash_from_sk(skb, sk); |
|
/* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */ |
|
skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb); |
|
skb_shinfo(skb)->gso_size = tcp_skb_mss(skb); |
|
|
|
/* Leave earliest departure time in skb->tstamp (skb->skb_mstamp_ns) */ |
|
|
|
/* Cleanup our debris for IP stacks */ |
|
memset(skb->cb, 0, max(sizeof(struct inet_skb_parm), |
|
sizeof(struct inet6_skb_parm))); |
|
|
|
tcp_add_tx_delay(skb, tp); |
|
|
|
err = INDIRECT_CALL_INET(icsk->icsk_af_ops->queue_xmit, |
|
inet6_csk_xmit, ip_queue_xmit, |
|
sk, skb, &inet->cork.fl); |
|
|
|
if (unlikely(err > 0)) { |
|
tcp_enter_cwr(sk); |
|
err = net_xmit_eval(err); |
|
} |
|
if (!err && oskb) { |
|
tcp_update_skb_after_send(sk, oskb, prior_wstamp); |
|
tcp_rate_skb_sent(sk, oskb); |
|
} |
|
return err; |
|
} |
|
|
|
static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, |
|
gfp_t gfp_mask) |
|
{ |
|
return __tcp_transmit_skb(sk, skb, clone_it, gfp_mask, |
|
tcp_sk(sk)->rcv_nxt); |
|
} |
|
|
|
/* This routine just queues the buffer for sending. |
|
* |
|
* NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, |
|
* otherwise socket can stall. |
|
*/ |
|
static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
|
|
/* Advance write_seq and place onto the write_queue. */ |
|
WRITE_ONCE(tp->write_seq, TCP_SKB_CB(skb)->end_seq); |
|
__skb_header_release(skb); |
|
tcp_add_write_queue_tail(sk, skb); |
|
sk_wmem_queued_add(sk, skb->truesize); |
|
sk_mem_charge(sk, skb->truesize); |
|
} |
|
|
|
/* Initialize TSO segments for a packet. */ |
|
static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now) |
|
{ |
|
if (skb->len <= mss_now) { |
|
/* Avoid the costly divide in the normal |
|
* non-TSO case. |
|
*/ |
|
tcp_skb_pcount_set(skb, 1); |
|
TCP_SKB_CB(skb)->tcp_gso_size = 0; |
|
} else { |
|
tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now)); |
|
TCP_SKB_CB(skb)->tcp_gso_size = mss_now; |
|
} |
|
} |
|
|
|
/* Pcount in the middle of the write queue got changed, we need to do various |
|
* tweaks to fix counters |
|
*/ |
|
static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
|
|
tp->packets_out -= decr; |
|
|
|
if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) |
|
tp->sacked_out -= decr; |
|
if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) |
|
tp->retrans_out -= decr; |
|
if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) |
|
tp->lost_out -= decr; |
|
|
|
/* Reno case is special. Sigh... */ |
|
if (tcp_is_reno(tp) && decr > 0) |
|
tp->sacked_out -= min_t(u32, tp->sacked_out, decr); |
|
|
|
if (tp->lost_skb_hint && |
|
before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && |
|
(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) |
|
tp->lost_cnt_hint -= decr; |
|
|
|
tcp_verify_left_out(tp); |
|
} |
|
|
|
static bool tcp_has_tx_tstamp(const struct sk_buff *skb) |
|
{ |
|
return TCP_SKB_CB(skb)->txstamp_ack || |
|
(skb_shinfo(skb)->tx_flags & SKBTX_ANY_TSTAMP); |
|
} |
|
|
|
static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2) |
|
{ |
|
struct skb_shared_info *shinfo = skb_shinfo(skb); |
|
|
|
if (unlikely(tcp_has_tx_tstamp(skb)) && |
|
!before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) { |
|
struct skb_shared_info *shinfo2 = skb_shinfo(skb2); |
|
u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP; |
|
|
|
shinfo->tx_flags &= ~tsflags; |
|
shinfo2->tx_flags |= tsflags; |
|
swap(shinfo->tskey, shinfo2->tskey); |
|
TCP_SKB_CB(skb2)->txstamp_ack = TCP_SKB_CB(skb)->txstamp_ack; |
|
TCP_SKB_CB(skb)->txstamp_ack = 0; |
|
} |
|
} |
|
|
|
static void tcp_skb_fragment_eor(struct sk_buff *skb, struct sk_buff *skb2) |
|
{ |
|
TCP_SKB_CB(skb2)->eor = TCP_SKB_CB(skb)->eor; |
|
TCP_SKB_CB(skb)->eor = 0; |
|
} |
|
|
|
/* Insert buff after skb on the write or rtx queue of sk. */ |
|
static void tcp_insert_write_queue_after(struct sk_buff *skb, |
|
struct sk_buff *buff, |
|
struct sock *sk, |
|
enum tcp_queue tcp_queue) |
|
{ |
|
if (tcp_queue == TCP_FRAG_IN_WRITE_QUEUE) |
|
__skb_queue_after(&sk->sk_write_queue, skb, buff); |
|
else |
|
tcp_rbtree_insert(&sk->tcp_rtx_queue, buff); |
|
} |
|
|
|
/* Function to create two new TCP segments. Shrinks the given segment |
|
* to the specified size and appends a new segment with the rest of the |
|
* packet to the list. This won't be called frequently, I hope. |
|
* Remember, these are still headerless SKBs at this point. |
|
*/ |
|
int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, |
|
struct sk_buff *skb, u32 len, |
|
unsigned int mss_now, gfp_t gfp) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
struct sk_buff *buff; |
|
int nsize, old_factor; |
|
long limit; |
|
int nlen; |
|
u8 flags; |
|
|
|
if (WARN_ON(len > skb->len)) |
|
return -EINVAL; |
|
|
|
nsize = skb_headlen(skb) - len; |
|
if (nsize < 0) |
|
nsize = 0; |
|
|
|
/* tcp_sendmsg() can overshoot sk_wmem_queued by one full size skb. |
|
* We need some allowance to not penalize applications setting small |
|
* SO_SNDBUF values. |
|
* Also allow first and last skb in retransmit queue to be split. |
|
*/ |
|
limit = sk->sk_sndbuf + 2 * SKB_TRUESIZE(GSO_MAX_SIZE); |
|
if (unlikely((sk->sk_wmem_queued >> 1) > limit && |
|
tcp_queue != TCP_FRAG_IN_WRITE_QUEUE && |
|
skb != tcp_rtx_queue_head(sk) && |
|
skb != tcp_rtx_queue_tail(sk))) { |
|
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPWQUEUETOOBIG); |
|
return -ENOMEM; |
|
} |
|
|
|
if (skb_unclone(skb, gfp)) |
|
return -ENOMEM; |
|
|
|
/* Get a new skb... force flag on. */ |
|
buff = sk_stream_alloc_skb(sk, nsize, gfp, true); |
|
if (!buff) |
|
return -ENOMEM; /* We'll just try again later. */ |
|
skb_copy_decrypted(buff, skb); |
|
mptcp_skb_ext_copy(buff, skb); |
|
|
|
sk_wmem_queued_add(sk, buff->truesize); |
|
sk_mem_charge(sk, buff->truesize); |
|
nlen = skb->len - len - nsize; |
|
buff->truesize += nlen; |
|
skb->truesize -= nlen; |
|
|
|
/* Correct the sequence numbers. */ |
|
TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; |
|
TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; |
|
TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; |
|
|
|
/* PSH and FIN should only be set in the second packet. */ |
|
flags = TCP_SKB_CB(skb)->tcp_flags; |
|
TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); |
|
TCP_SKB_CB(buff)->tcp_flags = flags; |
|
TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; |
|
tcp_skb_fragment_eor(skb, buff); |
|
|
|
skb_split(skb, buff, len); |
|
|
|
buff->ip_summed = CHECKSUM_PARTIAL; |
|
|
|
buff->tstamp = skb->tstamp; |
|
tcp_fragment_tstamp(skb, buff); |
|
|
|
old_factor = tcp_skb_pcount(skb); |
|
|
|
/* Fix up tso_factor for both original and new SKB. */ |
|
tcp_set_skb_tso_segs(skb, mss_now); |
|
tcp_set_skb_tso_segs(buff, mss_now); |
|
|
|
/* Update delivered info for the new segment */ |
|
TCP_SKB_CB(buff)->tx = TCP_SKB_CB(skb)->tx; |
|
|
|
/* If this packet has been sent out already, we must |
|
* adjust the various packet counters. |
|
*/ |
|
if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { |
|
int diff = old_factor - tcp_skb_pcount(skb) - |
|
tcp_skb_pcount(buff); |
|
|
|
if (diff) |
|
tcp_adjust_pcount(sk, skb, diff); |
|
} |
|
|
|
/* Link BUFF into the send queue. */ |
|
__skb_header_release(buff); |
|
tcp_insert_write_queue_after(skb, buff, sk, tcp_queue); |
|
if (tcp_queue == TCP_FRAG_IN_RTX_QUEUE) |
|
list_add(&buff->tcp_tsorted_anchor, &skb->tcp_tsorted_anchor); |
|
|
|
return 0; |
|
} |
|
|
|
/* This is similar to __pskb_pull_tail(). The difference is that pulled |
|
* data is not copied, but immediately discarded. |
|
*/ |
|
static int __pskb_trim_head(struct sk_buff *skb, int len) |
|
{ |
|
struct skb_shared_info *shinfo; |
|
int i, k, eat; |
|
|
|
eat = min_t(int, len, skb_headlen(skb)); |
|
if (eat) { |
|
__skb_pull(skb, eat); |
|
len -= eat; |
|
if (!len) |
|
return 0; |
|
} |
|
eat = len; |
|
k = 0; |
|
shinfo = skb_shinfo(skb); |
|
for (i = 0; i < shinfo->nr_frags; i++) { |
|
int size = skb_frag_size(&shinfo->frags[i]); |
|
|
|
if (size <= eat) { |
|
skb_frag_unref(skb, i); |
|
eat -= size; |
|
} else { |
|
shinfo->frags[k] = shinfo->frags[i]; |
|
if (eat) { |
|
skb_frag_off_add(&shinfo->frags[k], eat); |
|
skb_frag_size_sub(&shinfo->frags[k], eat); |
|
eat = 0; |
|
} |
|
k++; |
|
} |
|
} |
|
shinfo->nr_frags = k; |
|
|
|
skb->data_len -= len; |
|
skb->len = skb->data_len; |
|
return len; |
|
} |
|
|
|
/* Remove acked data from a packet in the transmit queue. */ |
|
int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) |
|
{ |
|
u32 delta_truesize; |
|
|
|
if (skb_unclone(skb, GFP_ATOMIC)) |
|
return -ENOMEM; |
|
|
|
delta_truesize = __pskb_trim_head(skb, len); |
|
|
|
TCP_SKB_CB(skb)->seq += len; |
|
skb->ip_summed = CHECKSUM_PARTIAL; |
|
|
|
if (delta_truesize) { |
|
skb->truesize -= delta_truesize; |
|
sk_wmem_queued_add(sk, -delta_truesize); |
|
sk_mem_uncharge(sk, delta_truesize); |
|
} |
|
|
|
/* Any change of skb->len requires recalculation of tso factor. */ |
|
if (tcp_skb_pcount(skb) > 1) |
|
tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb)); |
|
|
|
return 0; |
|
} |
|
|
|
/* Calculate MSS not accounting any TCP options. */ |
|
static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) |
|
{ |
|
const struct tcp_sock *tp = tcp_sk(sk); |
|
const struct inet_connection_sock *icsk = inet_csk(sk); |
|
int mss_now; |
|
|
|
/* Calculate base mss without TCP options: |
|
It is MMS_S - sizeof(tcphdr) of rfc1122 |
|
*/ |
|
mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); |
|
|
|
/* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ |
|
if (icsk->icsk_af_ops->net_frag_header_len) { |
|
const struct dst_entry *dst = __sk_dst_get(sk); |
|
|
|
if (dst && dst_allfrag(dst)) |
|
mss_now -= icsk->icsk_af_ops->net_frag_header_len; |
|
} |
|
|
|
/* Clamp it (mss_clamp does not include tcp options) */ |
|
if (mss_now > tp->rx_opt.mss_clamp) |
|
mss_now = tp->rx_opt.mss_clamp; |
|
|
|
/* Now subtract optional transport overhead */ |
|
mss_now -= icsk->icsk_ext_hdr_len; |
|
|
|
/* Then reserve room for full set of TCP options and 8 bytes of data */ |
|
mss_now = max(mss_now, sock_net(sk)->ipv4.sysctl_tcp_min_snd_mss); |
|
return mss_now; |
|
} |
|
|
|
/* Calculate MSS. Not accounting for SACKs here. */ |
|
int tcp_mtu_to_mss(struct sock *sk, int pmtu) |
|
{ |
|
/* Subtract TCP options size, not including SACKs */ |
|
return __tcp_mtu_to_mss(sk, pmtu) - |
|
(tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); |
|
} |
|
|
|
/* Inverse of above */ |
|
int tcp_mss_to_mtu(struct sock *sk, int mss) |
|
{ |
|
const struct tcp_sock *tp = tcp_sk(sk); |
|
const struct inet_connection_sock *icsk = inet_csk(sk); |
|
int mtu; |
|
|
|
mtu = mss + |
|
tp->tcp_header_len + |
|
icsk->icsk_ext_hdr_len + |
|
icsk->icsk_af_ops->net_header_len; |
|
|
|
/* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ |
|
if (icsk->icsk_af_ops->net_frag_header_len) { |
|
const struct dst_entry *dst = __sk_dst_get(sk); |
|
|
|
if (dst && dst_allfrag(dst)) |
|
mtu += icsk->icsk_af_ops->net_frag_header_len; |
|
} |
|
return mtu; |
|
} |
|
EXPORT_SYMBOL(tcp_mss_to_mtu); |
|
|
|
/* MTU probing init per socket */ |
|
void tcp_mtup_init(struct sock *sk) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
struct inet_connection_sock *icsk = inet_csk(sk); |
|
struct net *net = sock_net(sk); |
|
|
|
icsk->icsk_mtup.enabled = net->ipv4.sysctl_tcp_mtu_probing > 1; |
|
icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + |
|
icsk->icsk_af_ops->net_header_len; |
|
icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, net->ipv4.sysctl_tcp_base_mss); |
|
icsk->icsk_mtup.probe_size = 0; |
|
if (icsk->icsk_mtup.enabled) |
|
icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; |
|
} |
|
EXPORT_SYMBOL(tcp_mtup_init); |
|
|
|
/* This function synchronize snd mss to current pmtu/exthdr set. |
|
|
|
tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts |
|
for TCP options, but includes only bare TCP header. |
|
|
|
tp->rx_opt.mss_clamp is mss negotiated at connection setup. |
|
It is minimum of user_mss and mss received with SYN. |
|
It also does not include TCP options. |
|
|
|
inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. |
|
|
|
tp->mss_cache is current effective sending mss, including |
|
all tcp options except for SACKs. It is evaluated, |
|
taking into account current pmtu, but never exceeds |
|
tp->rx_opt.mss_clamp. |
|
|
|
NOTE1. rfc1122 clearly states that advertised MSS |
|
DOES NOT include either tcp or ip options. |
|
|
|
NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache |
|
are READ ONLY outside this function. --ANK (980731) |
|
*/ |
|
unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
struct inet_connection_sock *icsk = inet_csk(sk); |
|
int mss_now; |
|
|
|
if (icsk->icsk_mtup.search_high > pmtu) |
|
icsk->icsk_mtup.search_high = pmtu; |
|
|
|
mss_now = tcp_mtu_to_mss(sk, pmtu); |
|
mss_now = tcp_bound_to_half_wnd(tp, mss_now); |
|
|
|
/* And store cached results */ |
|
icsk->icsk_pmtu_cookie = pmtu; |
|
if (icsk->icsk_mtup.enabled) |
|
mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); |
|
tp->mss_cache = mss_now; |
|
|
|
return mss_now; |
|
} |
|
EXPORT_SYMBOL(tcp_sync_mss); |
|
|
|
/* Compute the current effective MSS, taking SACKs and IP options, |
|
* and even PMTU discovery events into account. |
|
*/ |
|
unsigned int tcp_current_mss(struct sock *sk) |
|
{ |
|
const struct tcp_sock *tp = tcp_sk(sk); |
|
const struct dst_entry *dst = __sk_dst_get(sk); |
|
u32 mss_now; |
|
unsigned int header_len; |
|
struct tcp_out_options opts; |
|
struct tcp_md5sig_key *md5; |
|
|
|
mss_now = tp->mss_cache; |
|
|
|
if (dst) { |
|
u32 mtu = dst_mtu(dst); |
|
if (mtu != inet_csk(sk)->icsk_pmtu_cookie) |
|
mss_now = tcp_sync_mss(sk, mtu); |
|
} |
|
|
|
header_len = tcp_established_options(sk, NULL, &opts, &md5) + |
|
sizeof(struct tcphdr); |
|
/* The mss_cache is sized based on tp->tcp_header_len, which assumes |
|
* some common options. If this is an odd packet (because we have SACK |
|
* blocks etc) then our calculated header_len will be different, and |
|
* we have to adjust mss_now correspondingly */ |
|
if (header_len != tp->tcp_header_len) { |
|
int delta = (int) header_len - tp->tcp_header_len; |
|
mss_now -= delta; |
|
} |
|
|
|
return mss_now; |
|
} |
|
|
|
/* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. |
|
* As additional protections, we do not touch cwnd in retransmission phases, |
|
* and if application hit its sndbuf limit recently. |
|
*/ |
|
static void tcp_cwnd_application_limited(struct sock *sk) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
|
|
if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && |
|
sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { |
|
/* Limited by application or receiver window. */ |
|
u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk)); |
|
u32 win_used = max(tp->snd_cwnd_used, init_win); |
|
if (win_used < tp->snd_cwnd) { |
|
tp->snd_ssthresh = tcp_current_ssthresh(sk); |
|
tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1; |
|
} |
|
tp->snd_cwnd_used = 0; |
|
} |
|
tp->snd_cwnd_stamp = tcp_jiffies32; |
|
} |
|
|
|
static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) |
|
{ |
|
const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
|
|
/* Track the maximum number of outstanding packets in each |
|
* window, and remember whether we were cwnd-limited then. |
|
*/ |
|
if (!before(tp->snd_una, tp->max_packets_seq) || |
|
tp->packets_out > tp->max_packets_out || |
|
is_cwnd_limited) { |
|
tp->max_packets_out = tp->packets_out; |
|
tp->max_packets_seq = tp->snd_nxt; |
|
tp->is_cwnd_limited = is_cwnd_limited; |
|
} |
|
|
|
if (tcp_is_cwnd_limited(sk)) { |
|
/* Network is feed fully. */ |
|
tp->snd_cwnd_used = 0; |
|
tp->snd_cwnd_stamp = tcp_jiffies32; |
|
} else { |
|
/* Network starves. */ |
|
if (tp->packets_out > tp->snd_cwnd_used) |
|
tp->snd_cwnd_used = tp->packets_out; |
|
|
|
if (sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle && |
|
(s32)(tcp_jiffies32 - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto && |
|
!ca_ops->cong_control) |
|
tcp_cwnd_application_limited(sk); |
|
|
|
/* The following conditions together indicate the starvation |
|
* is caused by insufficient sender buffer: |
|
* 1) just sent some data (see tcp_write_xmit) |
|
* 2) not cwnd limited (this else condition) |
|
* 3) no more data to send (tcp_write_queue_empty()) |
|
* 4) application is hitting buffer limit (SOCK_NOSPACE) |
|
*/ |
|
if (tcp_write_queue_empty(sk) && sk->sk_socket && |
|
test_bit(SOCK_NOSPACE, &sk->sk_socket->flags) && |
|
(1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) |
|
tcp_chrono_start(sk, TCP_CHRONO_SNDBUF_LIMITED); |
|
} |
|
} |
|
|
|
/* Minshall's variant of the Nagle send check. */ |
|
static bool tcp_minshall_check(const struct tcp_sock *tp) |
|
{ |
|
return after(tp->snd_sml, tp->snd_una) && |
|
!after(tp->snd_sml, tp->snd_nxt); |
|
} |
|
|
|
/* Update snd_sml if this skb is under mss |
|
* Note that a TSO packet might end with a sub-mss segment |
|
* The test is really : |
|
* if ((skb->len % mss) != 0) |
|
* tp->snd_sml = TCP_SKB_CB(skb)->end_seq; |
|
* But we can avoid doing the divide again given we already have |
|
* skb_pcount = skb->len / mss_now |
|
*/ |
|
static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, |
|
const struct sk_buff *skb) |
|
{ |
|
if (skb->len < tcp_skb_pcount(skb) * mss_now) |
|
tp->snd_sml = TCP_SKB_CB(skb)->end_seq; |
|
} |
|
|
|
/* Return false, if packet can be sent now without violation Nagle's rules: |
|
* 1. It is full sized. (provided by caller in %partial bool) |
|
* 2. Or it contains FIN. (already checked by caller) |
|
* 3. Or TCP_CORK is not set, and TCP_NODELAY is set. |
|
* 4. Or TCP_CORK is not set, and all sent packets are ACKed. |
|
* With Minshall's modification: all sent small packets are ACKed. |
|
*/ |
|
static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, |
|
int nonagle) |
|
{ |
|
return partial && |
|
((nonagle & TCP_NAGLE_CORK) || |
|
(!nonagle && tp->packets_out && tcp_minshall_check(tp))); |
|
} |
|
|
|
/* Return how many segs we'd like on a TSO packet, |
|
* to send one TSO packet per ms |
|
*/ |
|
static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, |
|
int min_tso_segs) |
|
{ |
|
u32 bytes, segs; |
|
|
|
bytes = min_t(unsigned long, |
|
sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift), |
|
sk->sk_gso_max_size - 1 - MAX_TCP_HEADER); |
|
|
|
/* Goal is to send at least one packet per ms, |
|
* not one big TSO packet every 100 ms. |
|
* This preserves ACK clocking and is consistent |
|
* with tcp_tso_should_defer() heuristic. |
|
*/ |
|
segs = max_t(u32, bytes / mss_now, min_tso_segs); |
|
|
|
return segs; |
|
} |
|
|
|
/* Return the number of segments we want in the skb we are transmitting. |
|
* See if congestion control module wants to decide; otherwise, autosize. |
|
*/ |
|
static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now) |
|
{ |
|
const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; |
|
u32 min_tso, tso_segs; |
|
|
|
min_tso = ca_ops->min_tso_segs ? |
|
ca_ops->min_tso_segs(sk) : |
|
sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs; |
|
|
|
tso_segs = tcp_tso_autosize(sk, mss_now, min_tso); |
|
return min_t(u32, tso_segs, sk->sk_gso_max_segs); |
|
} |
|
|
|
/* Returns the portion of skb which can be sent right away */ |
|
static unsigned int tcp_mss_split_point(const struct sock *sk, |
|
const struct sk_buff *skb, |
|
unsigned int mss_now, |
|
unsigned int max_segs, |
|
int nonagle) |
|
{ |
|
const struct tcp_sock *tp = tcp_sk(sk); |
|
u32 partial, needed, window, max_len; |
|
|
|
window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
|
max_len = mss_now * max_segs; |
|
|
|
if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) |
|
return max_len; |
|
|
|
needed = min(skb->len, window); |
|
|
|
if (max_len <= needed) |
|
return max_len; |
|
|
|
partial = needed % mss_now; |
|
/* If last segment is not a full MSS, check if Nagle rules allow us |
|
* to include this last segment in this skb. |
|
* Otherwise, we'll split the skb at last MSS boundary |
|
*/ |
|
if (tcp_nagle_check(partial != 0, tp, nonagle)) |
|
return needed - partial; |
|
|
|
return needed; |
|
} |
|
|
|
/* Can at least one segment of SKB be sent right now, according to the |
|
* congestion window rules? If so, return how many segments are allowed. |
|
*/ |
|
static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, |
|
const struct sk_buff *skb) |
|
{ |
|
u32 in_flight, cwnd, halfcwnd; |
|
|
|
/* Don't be strict about the congestion window for the final FIN. */ |
|
if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && |
|
tcp_skb_pcount(skb) == 1) |
|
return 1; |
|
|
|
in_flight = tcp_packets_in_flight(tp); |
|
cwnd = tp->snd_cwnd; |
|
if (in_flight >= cwnd) |
|
return 0; |
|
|
|
/* For better scheduling, ensure we have at least |
|
* 2 GSO packets in flight. |
|
*/ |
|
halfcwnd = max(cwnd >> 1, 1U); |
|
return min(halfcwnd, cwnd - in_flight); |
|
} |
|
|
|
/* Initialize TSO state of a skb. |
|
* This must be invoked the first time we consider transmitting |
|
* SKB onto the wire. |
|
*/ |
|
static int tcp_init_tso_segs(struct sk_buff *skb, unsigned int mss_now) |
|
{ |
|
int tso_segs = tcp_skb_pcount(skb); |
|
|
|
if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { |
|
tcp_set_skb_tso_segs(skb, mss_now); |
|
tso_segs = tcp_skb_pcount(skb); |
|
} |
|
return tso_segs; |
|
} |
|
|
|
|
|
/* Return true if the Nagle test allows this packet to be |
|
* sent now. |
|
*/ |
|
static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, |
|
unsigned int cur_mss, int nonagle) |
|
{ |
|
/* Nagle rule does not apply to frames, which sit in the middle of the |
|
* write_queue (they have no chances to get new data). |
|
* |
|
* This is implemented in the callers, where they modify the 'nonagle' |
|
* argument based upon the location of SKB in the send queue. |
|
*/ |
|
if (nonagle & TCP_NAGLE_PUSH) |
|
return true; |
|
|
|
/* Don't use the nagle rule for urgent data (or for the final FIN). */ |
|
if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) |
|
return true; |
|
|
|
if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle)) |
|
return true; |
|
|
|
return false; |
|
} |
|
|
|
/* Does at least the first segment of SKB fit into the send window? */ |
|
static bool tcp_snd_wnd_test(const struct tcp_sock *tp, |
|
const struct sk_buff *skb, |
|
unsigned int cur_mss) |
|
{ |
|
u32 end_seq = TCP_SKB_CB(skb)->end_seq; |
|
|
|
if (skb->len > cur_mss) |
|
end_seq = TCP_SKB_CB(skb)->seq + cur_mss; |
|
|
|
return !after(end_seq, tcp_wnd_end(tp)); |
|
} |
|
|
|
/* Trim TSO SKB to LEN bytes, put the remaining data into a new packet |
|
* which is put after SKB on the list. It is very much like |
|
* tcp_fragment() except that it may make several kinds of assumptions |
|
* in order to speed up the splitting operation. In particular, we |
|
* know that all the data is in scatter-gather pages, and that the |
|
* packet has never been sent out before (and thus is not cloned). |
|
*/ |
|
static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, |
|
unsigned int mss_now, gfp_t gfp) |
|
{ |
|
int nlen = skb->len - len; |
|
struct sk_buff *buff; |
|
u8 flags; |
|
|
|
/* All of a TSO frame must be composed of paged data. */ |
|
if (skb->len != skb->data_len) |
|
return tcp_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE, |
|
skb, len, mss_now, gfp); |
|
|
|
buff = sk_stream_alloc_skb(sk, 0, gfp, true); |
|
if (unlikely(!buff)) |
|
return -ENOMEM; |
|
skb_copy_decrypted(buff, skb); |
|
mptcp_skb_ext_copy(buff, skb); |
|
|
|
sk_wmem_queued_add(sk, buff->truesize); |
|
sk_mem_charge(sk, buff->truesize); |
|
buff->truesize += nlen; |
|
skb->truesize -= nlen; |
|
|
|
/* Correct the sequence numbers. */ |
|
TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; |
|
TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; |
|
TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; |
|
|
|
/* PSH and FIN should only be set in the second packet. */ |
|
flags = TCP_SKB_CB(skb)->tcp_flags; |
|
TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); |
|
TCP_SKB_CB(buff)->tcp_flags = flags; |
|
|
|
/* This packet was never sent out yet, so no SACK bits. */ |
|
TCP_SKB_CB(buff)->sacked = 0; |
|
|
|
tcp_skb_fragment_eor(skb, buff); |
|
|
|
buff->ip_summed = CHECKSUM_PARTIAL; |
|
skb_split(skb, buff, len); |
|
tcp_fragment_tstamp(skb, buff); |
|
|
|
/* Fix up tso_factor for both original and new SKB. */ |
|
tcp_set_skb_tso_segs(skb, mss_now); |
|
tcp_set_skb_tso_segs(buff, mss_now); |
|
|
|
/* Link BUFF into the send queue. */ |
|
__skb_header_release(buff); |
|
tcp_insert_write_queue_after(skb, buff, sk, TCP_FRAG_IN_WRITE_QUEUE); |
|
|
|
return 0; |
|
} |
|
|
|
/* Try to defer sending, if possible, in order to minimize the amount |
|
* of TSO splitting we do. View it as a kind of TSO Nagle test. |
|
* |
|
* This algorithm is from John Heffner. |
|
*/ |
|
static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, |
|
bool *is_cwnd_limited, |
|
bool *is_rwnd_limited, |
|
u32 max_segs) |
|
{ |
|
const struct inet_connection_sock *icsk = inet_csk(sk); |
|
u32 send_win, cong_win, limit, in_flight; |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
struct sk_buff *head; |
|
int win_divisor; |
|
s64 delta; |
|
|
|
if (icsk->icsk_ca_state >= TCP_CA_Recovery) |
|
goto send_now; |
|
|
|
/* Avoid bursty behavior by allowing defer |
|
* only if the last write was recent (1 ms). |
|
* Note that tp->tcp_wstamp_ns can be in the future if we have |
|
* packets waiting in a qdisc or device for EDT delivery. |
|
*/ |
|
delta = tp->tcp_clock_cache - tp->tcp_wstamp_ns - NSEC_PER_MSEC; |
|
if (delta > 0) |
|
goto send_now; |
|
|
|
in_flight = tcp_packets_in_flight(tp); |
|
|
|
BUG_ON(tcp_skb_pcount(skb) <= 1); |
|
BUG_ON(tp->snd_cwnd <= in_flight); |
|
|
|
send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
|
|
|
/* From in_flight test above, we know that cwnd > in_flight. */ |
|
cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; |
|
|
|
limit = min(send_win, cong_win); |
|
|
|
/* If a full-sized TSO skb can be sent, do it. */ |
|
if (limit >= max_segs * tp->mss_cache) |
|
goto send_now; |
|
|
|
/* Middle in queue won't get any more data, full sendable already? */ |
|
if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) |
|
goto send_now; |
|
|
|
win_divisor = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_tso_win_divisor); |
|
if (win_divisor) { |
|
u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); |
|
|
|
/* If at least some fraction of a window is available, |
|
* just use it. |
|
*/ |
|
chunk /= win_divisor; |
|
if (limit >= chunk) |
|
goto send_now; |
|
} else { |
|
/* Different approach, try not to defer past a single |
|
* ACK. Receiver should ACK every other full sized |
|
* frame, so if we have space for more than 3 frames |
|
* then send now. |
|
*/ |
|
if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) |
|
goto send_now; |
|
} |
|
|
|
/* TODO : use tsorted_sent_queue ? */ |
|
head = tcp_rtx_queue_head(sk); |
|
if (!head) |
|
goto send_now; |
|
delta = tp->tcp_clock_cache - head->tstamp; |
|
/* If next ACK is likely to come too late (half srtt), do not defer */ |
|
if ((s64)(delta - (u64)NSEC_PER_USEC * (tp->srtt_us >> 4)) < 0) |
|
goto send_now; |
|
|
|
/* Ok, it looks like it is advisable to defer. |
|
* Three cases are tracked : |
|
* 1) We are cwnd-limited |
|
* 2) We are rwnd-limited |
|
* 3) We are application limited. |
|
*/ |
|
if (cong_win < send_win) { |
|
if (cong_win <= skb->len) { |
|
*is_cwnd_limited = true; |
|
return true; |
|
} |
|
} else { |
|
if (send_win <= skb->len) { |
|
*is_rwnd_limited = true; |
|
return true; |
|
} |
|
} |
|
|
|
/* If this packet won't get more data, do not wait. */ |
|
if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) || |
|
TCP_SKB_CB(skb)->eor) |
|
goto send_now; |
|
|
|
return true; |
|
|
|
send_now: |
|
return false; |
|
} |
|
|
|
static inline void tcp_mtu_check_reprobe(struct sock *sk) |
|
{ |
|
struct inet_connection_sock *icsk = inet_csk(sk); |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
struct net *net = sock_net(sk); |
|
u32 interval; |
|
s32 delta; |
|
|
|
interval = net->ipv4.sysctl_tcp_probe_interval; |
|
delta = tcp_jiffies32 - icsk->icsk_mtup.probe_timestamp; |
|
if (unlikely(delta >= interval * HZ)) { |
|
int mss = tcp_current_mss(sk); |
|
|
|
/* Update current search range */ |
|
icsk->icsk_mtup.probe_size = 0; |
|
icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + |
|
sizeof(struct tcphdr) + |
|
icsk->icsk_af_ops->net_header_len; |
|
icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); |
|
|
|
/* Update probe time stamp */ |
|
icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; |
|
} |
|
} |
|
|
|
static bool tcp_can_coalesce_send_queue_head(struct sock *sk, int len) |
|
{ |
|
struct sk_buff *skb, *next; |
|
|
|
skb = tcp_send_head(sk); |
|
tcp_for_write_queue_from_safe(skb, next, sk) { |
|
if (len <= skb->len) |
|
break; |
|
|
|
if (unlikely(TCP_SKB_CB(skb)->eor) || tcp_has_tx_tstamp(skb)) |
|
return false; |
|
|
|
len -= skb->len; |
|
} |
|
|
|
return true; |
|
} |
|
|
|
/* Create a new MTU probe if we are ready. |
|
* MTU probe is regularly attempting to increase the path MTU by |
|
* deliberately sending larger packets. This discovers routing |
|
* changes resulting in larger path MTUs. |
|
* |
|
* Returns 0 if we should wait to probe (no cwnd available), |
|
* 1 if a probe was sent, |
|
* -1 otherwise |
|
*/ |
|
static int tcp_mtu_probe(struct sock *sk) |
|
{ |
|
struct inet_connection_sock *icsk = inet_csk(sk); |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
struct sk_buff *skb, *nskb, *next; |
|
struct net *net = sock_net(sk); |
|
int probe_size; |
|
int size_needed; |
|
int copy, len; |
|
int mss_now; |
|
int interval; |
|
|
|
/* Not currently probing/verifying, |
|
* not in recovery, |
|
* have enough cwnd, and |
|
* not SACKing (the variable headers throw things off) |
|
*/ |
|
if (likely(!icsk->icsk_mtup.enabled || |
|
icsk->icsk_mtup.probe_size || |
|
inet_csk(sk)->icsk_ca_state != TCP_CA_Open || |
|
tp->snd_cwnd < 11 || |
|
tp->rx_opt.num_sacks || tp->rx_opt.dsack)) |
|
return -1; |
|
|
|
/* Use binary search for probe_size between tcp_mss_base, |
|
* and current mss_clamp. if (search_high - search_low) |
|
* smaller than a threshold, backoff from probing. |
|
*/ |
|
mss_now = tcp_current_mss(sk); |
|
probe_size = tcp_mtu_to_mss(sk, (icsk->icsk_mtup.search_high + |
|
icsk->icsk_mtup.search_low) >> 1); |
|
size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; |
|
interval = icsk->icsk_mtup.search_high - icsk->icsk_mtup.search_low; |
|
/* When misfortune happens, we are reprobing actively, |
|
* and then reprobe timer has expired. We stick with current |
|
* probing process by not resetting search range to its orignal. |
|
*/ |
|
if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high) || |
|
interval < net->ipv4.sysctl_tcp_probe_threshold) { |
|
/* Check whether enough time has elaplased for |
|
* another round of probing. |
|
*/ |
|
tcp_mtu_check_reprobe(sk); |
|
return -1; |
|
} |
|
|
|
/* Have enough data in the send queue to probe? */ |
|
if (tp->write_seq - tp->snd_nxt < size_needed) |
|
return -1; |
|
|
|
if (tp->snd_wnd < size_needed) |
|
return -1; |
|
if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) |
|
return 0; |
|
|
|
/* Do we need to wait to drain cwnd? With none in flight, don't stall */ |
|
if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) { |
|
if (!tcp_packets_in_flight(tp)) |
|
return -1; |
|
else |
|
return 0; |
|
} |
|
|
|
if (!tcp_can_coalesce_send_queue_head(sk, probe_size)) |
|
return -1; |
|
|
|
/* We're allowed to probe. Build it now. */ |
|
nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC, false); |
|
if (!nskb) |
|
return -1; |
|
sk_wmem_queued_add(sk, nskb->truesize); |
|
sk_mem_charge(sk, nskb->truesize); |
|
|
|
skb = tcp_send_head(sk); |
|
skb_copy_decrypted(nskb, skb); |
|
mptcp_skb_ext_copy(nskb, skb); |
|
|
|
TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; |
|
TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; |
|
TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; |
|
TCP_SKB_CB(nskb)->sacked = 0; |
|
nskb->csum = 0; |
|
nskb->ip_summed = CHECKSUM_PARTIAL; |
|
|
|
tcp_insert_write_queue_before(nskb, skb, sk); |
|
tcp_highest_sack_replace(sk, skb, nskb); |
|
|
|
len = 0; |
|
tcp_for_write_queue_from_safe(skb, next, sk) { |
|
copy = min_t(int, skb->len, probe_size - len); |
|
skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); |
|
|
|
if (skb->len <= copy) { |
|
/* We've eaten all the data from this skb. |
|
* Throw it away. */ |
|
TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; |
|
/* If this is the last SKB we copy and eor is set |
|
* we need to propagate it to the new skb. |
|
*/ |
|
TCP_SKB_CB(nskb)->eor = TCP_SKB_CB(skb)->eor; |
|
tcp_skb_collapse_tstamp(nskb, skb); |
|
tcp_unlink_write_queue(skb, sk); |
|
sk_wmem_free_skb(sk, skb); |
|
} else { |
|
TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & |
|
~(TCPHDR_FIN|TCPHDR_PSH); |
|
if (!skb_shinfo(skb)->nr_frags) { |
|
skb_pull(skb, copy); |
|
} else { |
|
__pskb_trim_head(skb, copy); |
|
tcp_set_skb_tso_segs(skb, mss_now); |
|
} |
|
TCP_SKB_CB(skb)->seq += copy; |
|
} |
|
|
|
len += copy; |
|
|
|
if (len >= probe_size) |
|
break; |
|
} |
|
tcp_init_tso_segs(nskb, nskb->len); |
|
|
|
/* We're ready to send. If this fails, the probe will |
|
* be resegmented into mss-sized pieces by tcp_write_xmit(). |
|
*/ |
|
if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { |
|
/* Decrement cwnd here because we are sending |
|
* effectively two packets. */ |
|
tp->snd_cwnd--; |
|
tcp_event_new_data_sent(sk, nskb); |
|
|
|
icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); |
|
tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; |
|
tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; |
|
|
|
return 1; |
|
} |
|
|
|
return -1; |
|
} |
|
|
|
static bool tcp_pacing_check(struct sock *sk) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
|
|
if (!tcp_needs_internal_pacing(sk)) |
|
return false; |
|
|
|
if (tp->tcp_wstamp_ns <= tp->tcp_clock_cache) |
|
return false; |
|
|
|
if (!hrtimer_is_queued(&tp->pacing_timer)) { |
|
hrtimer_start(&tp->pacing_timer, |
|
ns_to_ktime(tp->tcp_wstamp_ns), |
|
HRTIMER_MODE_ABS_PINNED_SOFT); |
|
sock_hold(sk); |
|
} |
|
return true; |
|
} |
|
|
|
/* TCP Small Queues : |
|
* Control number of packets in qdisc/devices to two packets / or ~1 ms. |
|
* (These limits are doubled for retransmits) |
|
* This allows for : |
|
* - better RTT estimation and ACK scheduling |
|
* - faster recovery |
|
* - high rates |
|
* Alas, some drivers / subsystems require a fair amount |
|
* of queued bytes to ensure line rate. |
|
* One example is wifi aggregation (802.11 AMPDU) |
|
*/ |
|
static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb, |
|
unsigned int factor) |
|
{ |
|
unsigned long limit; |
|
|
|
limit = max_t(unsigned long, |
|
2 * skb->truesize, |
|
sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift)); |
|
if (sk->sk_pacing_status == SK_PACING_NONE) |
|
limit = min_t(unsigned long, limit, |
|
sock_net(sk)->ipv4.sysctl_tcp_limit_output_bytes); |
|
limit <<= factor; |
|
|
|
if (static_branch_unlikely(&tcp_tx_delay_enabled) && |
|
tcp_sk(sk)->tcp_tx_delay) { |
|
u64 extra_bytes = (u64)sk->sk_pacing_rate * tcp_sk(sk)->tcp_tx_delay; |
|
|
|
/* TSQ is based on skb truesize sum (sk_wmem_alloc), so we |
|
* approximate our needs assuming an ~100% skb->truesize overhead. |
|
* USEC_PER_SEC is approximated by 2^20. |
|
* do_div(extra_bytes, USEC_PER_SEC/2) is replaced by a right shift. |
|
*/ |
|
extra_bytes >>= (20 - 1); |
|
limit += extra_bytes; |
|
} |
|
if (refcount_read(&sk->sk_wmem_alloc) > limit) { |
|
/* Always send skb if rtx queue is empty. |
|
* No need to wait for TX completion to call us back, |
|
* after softirq/tasklet schedule. |
|
* This helps when TX completions are delayed too much. |
|
*/ |
|
if (tcp_rtx_queue_empty(sk)) |
|
return false; |
|
|
|
set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags); |
|
/* It is possible TX completion already happened |
|
* before we set TSQ_THROTTLED, so we must |
|
* test again the condition. |
|
*/ |
|
smp_mb__after_atomic(); |
|
if (refcount_read(&sk->sk_wmem_alloc) > limit) |
|
return true; |
|
} |
|
return false; |
|
} |
|
|
|
static void tcp_chrono_set(struct tcp_sock *tp, const enum tcp_chrono new) |
|
{ |
|
const u32 now = tcp_jiffies32; |
|
enum tcp_chrono old = tp->chrono_type; |
|
|
|
if (old > TCP_CHRONO_UNSPEC) |
|
tp->chrono_stat[old - 1] += now - tp->chrono_start; |
|
tp->chrono_start = now; |
|
tp->chrono_type = new; |
|
} |
|
|
|
void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
|
|
/* If there are multiple conditions worthy of tracking in a |
|
* chronograph then the highest priority enum takes precedence |
|
* over the other conditions. So that if something "more interesting" |
|
* starts happening, stop the previous chrono and start a new one. |
|
*/ |
|
if (type > tp->chrono_type) |
|
tcp_chrono_set(tp, type); |
|
} |
|
|
|
void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
|
|
|
|
/* There are multiple conditions worthy of tracking in a |
|
* chronograph, so that the highest priority enum takes |
|
* precedence over the other conditions (see tcp_chrono_start). |
|
* If a condition stops, we only stop chrono tracking if |
|
* it's the "most interesting" or current chrono we are |
|
* tracking and starts busy chrono if we have pending data. |
|
*/ |
|
if (tcp_rtx_and_write_queues_empty(sk)) |
|
tcp_chrono_set(tp, TCP_CHRONO_UNSPEC); |
|
else if (type == tp->chrono_type) |
|
tcp_chrono_set(tp, TCP_CHRONO_BUSY); |
|
} |
|
|
|
/* This routine writes packets to the network. It advances the |
|
* send_head. This happens as incoming acks open up the remote |
|
* window for us. |
|
* |
|
* LARGESEND note: !tcp_urg_mode is overkill, only frames between |
|
* snd_up-64k-mss .. snd_up cannot be large. However, taking into |
|
* account rare use of URG, this is not a big flaw. |
|
* |
|
* Send at most one packet when push_one > 0. Temporarily ignore |
|
* cwnd limit to force at most one packet out when push_one == 2. |
|
|
|
* Returns true, if no segments are in flight and we have queued segments, |
|
* but cannot send anything now because of SWS or another problem. |
|
*/ |
|
static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, |
|
int push_one, gfp_t gfp) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
struct sk_buff *skb; |
|
unsigned int tso_segs, sent_pkts; |
|
int cwnd_quota; |
|
int result; |
|
bool is_cwnd_limited = false, is_rwnd_limited = false; |
|
u32 max_segs; |
|
|
|
sent_pkts = 0; |
|
|
|
tcp_mstamp_refresh(tp); |
|
if (!push_one) { |
|
/* Do MTU probing. */ |
|
result = tcp_mtu_probe(sk); |
|
if (!result) { |
|
return false; |
|
} else if (result > 0) { |
|
sent_pkts = 1; |
|
} |
|
} |
|
|
|
max_segs = tcp_tso_segs(sk, mss_now); |
|
while ((skb = tcp_send_head(sk))) { |
|
unsigned int limit; |
|
|
|
if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { |
|
/* "skb_mstamp_ns" is used as a start point for the retransmit timer */ |
|
skb->skb_mstamp_ns = tp->tcp_wstamp_ns = tp->tcp_clock_cache; |
|
list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); |
|
tcp_init_tso_segs(skb, mss_now); |
|
goto repair; /* Skip network transmission */ |
|
} |
|
|
|
if (tcp_pacing_check(sk)) |
|
break; |
|
|
|
tso_segs = tcp_init_tso_segs(skb, mss_now); |
|
BUG_ON(!tso_segs); |
|
|
|
cwnd_quota = tcp_cwnd_test(tp, skb); |
|
if (!cwnd_quota) { |
|
if (push_one == 2) |
|
/* Force out a loss probe pkt. */ |
|
cwnd_quota = 1; |
|
else |
|
break; |
|
} |
|
|
|
if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) { |
|
is_rwnd_limited = true; |
|
break; |
|
} |
|
|
|
if (tso_segs == 1) { |
|
if (unlikely(!tcp_nagle_test(tp, skb, mss_now, |
|
(tcp_skb_is_last(sk, skb) ? |
|
nonagle : TCP_NAGLE_PUSH)))) |
|
break; |
|
} else { |
|
if (!push_one && |
|
tcp_tso_should_defer(sk, skb, &is_cwnd_limited, |
|
&is_rwnd_limited, max_segs)) |
|
break; |
|
} |
|
|
|
limit = mss_now; |
|
if (tso_segs > 1 && !tcp_urg_mode(tp)) |
|
limit = tcp_mss_split_point(sk, skb, mss_now, |
|
min_t(unsigned int, |
|
cwnd_quota, |
|
max_segs), |
|
nonagle); |
|
|
|
if (skb->len > limit && |
|
unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) |
|
break; |
|
|
|
if (tcp_small_queue_check(sk, skb, 0)) |
|
break; |
|
|
|
/* Argh, we hit an empty skb(), presumably a thread |
|
* is sleeping in sendmsg()/sk_stream_wait_memory(). |
|
* We do not want to send a pure-ack packet and have |
|
* a strange looking rtx queue with empty packet(s). |
|
*/ |
|
if (TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq) |
|
break; |
|
|
|
if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) |
|
break; |
|
|
|
repair: |
|
/* Advance the send_head. This one is sent out. |
|
* This call will increment packets_out. |
|
*/ |
|
tcp_event_new_data_sent(sk, skb); |
|
|
|
tcp_minshall_update(tp, mss_now, skb); |
|
sent_pkts += tcp_skb_pcount(skb); |
|
|
|
if (push_one) |
|
break; |
|
} |
|
|
|
if (is_rwnd_limited) |
|
tcp_chrono_start(sk, TCP_CHRONO_RWND_LIMITED); |
|
else |
|
tcp_chrono_stop(sk, TCP_CHRONO_RWND_LIMITED); |
|
|
|
is_cwnd_limited |= (tcp_packets_in_flight(tp) >= tp->snd_cwnd); |
|
if (likely(sent_pkts || is_cwnd_limited)) |
|
tcp_cwnd_validate(sk, is_cwnd_limited); |
|
|
|
if (likely(sent_pkts)) { |
|
if (tcp_in_cwnd_reduction(sk)) |
|
tp->prr_out += sent_pkts; |
|
|
|
/* Send one loss probe per tail loss episode. */ |
|
if (push_one != 2) |
|
tcp_schedule_loss_probe(sk, false); |
|
return false; |
|
} |
|
return !tp->packets_out && !tcp_write_queue_empty(sk); |
|
} |
|
|
|
bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto) |
|
{ |
|
struct inet_connection_sock *icsk = inet_csk(sk); |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
u32 timeout, rto_delta_us; |
|
int early_retrans; |
|
|
|
/* Don't do any loss probe on a Fast Open connection before 3WHS |
|
* finishes. |
|
*/ |
|
if (rcu_access_pointer(tp->fastopen_rsk)) |
|
return false; |
|
|
|
early_retrans = sock_net(sk)->ipv4.sysctl_tcp_early_retrans; |
|
/* Schedule a loss probe in 2*RTT for SACK capable connections |
|
* not in loss recovery, that are either limited by cwnd or application. |
|
*/ |
|
if ((early_retrans != 3 && early_retrans != 4) || |
|
!tp->packets_out || !tcp_is_sack(tp) || |
|
(icsk->icsk_ca_state != TCP_CA_Open && |
|
icsk->icsk_ca_state != TCP_CA_CWR)) |
|
return false; |
|
|
|
/* Probe timeout is 2*rtt. Add minimum RTO to account |
|
* for delayed ack when there's one outstanding packet. If no RTT |
|
* sample is available then probe after TCP_TIMEOUT_INIT. |
|
*/ |
|
if (tp->srtt_us) { |
|
timeout = usecs_to_jiffies(tp->srtt_us >> 2); |
|
if (tp->packets_out == 1) |
|
timeout += TCP_RTO_MIN; |
|
else |
|
timeout += TCP_TIMEOUT_MIN; |
|
} else { |
|
timeout = TCP_TIMEOUT_INIT; |
|
} |
|
|
|
/* If the RTO formula yields an earlier time, then use that time. */ |
|
rto_delta_us = advancing_rto ? |
|
jiffies_to_usecs(inet_csk(sk)->icsk_rto) : |
|
tcp_rto_delta_us(sk); /* How far in future is RTO? */ |
|
if (rto_delta_us > 0) |
|
timeout = min_t(u32, timeout, usecs_to_jiffies(rto_delta_us)); |
|
|
|
tcp_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, TCP_RTO_MAX); |
|
return true; |
|
} |
|
|
|
/* Thanks to skb fast clones, we can detect if a prior transmit of |
|
* a packet is still in a qdisc or driver queue. |
|
* In this case, there is very little point doing a retransmit ! |
|
*/ |
|
static bool skb_still_in_host_queue(const struct sock *sk, |
|
const struct sk_buff *skb) |
|
{ |
|
if (unlikely(skb_fclone_busy(sk, skb))) { |
|
NET_INC_STATS(sock_net(sk), |
|
LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); |
|
return true; |
|
} |
|
return false; |
|
} |
|
|
|
/* When probe timeout (PTO) fires, try send a new segment if possible, else |
|
* retransmit the last segment. |
|
*/ |
|
void tcp_send_loss_probe(struct sock *sk) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
struct sk_buff *skb; |
|
int pcount; |
|
int mss = tcp_current_mss(sk); |
|
|
|
/* At most one outstanding TLP */ |
|
if (tp->tlp_high_seq) |
|
goto rearm_timer; |
|
|
|
tp->tlp_retrans = 0; |
|
skb = tcp_send_head(sk); |
|
if (skb && tcp_snd_wnd_test(tp, skb, mss)) { |
|
pcount = tp->packets_out; |
|
tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); |
|
if (tp->packets_out > pcount) |
|
goto probe_sent; |
|
goto rearm_timer; |
|
} |
|
skb = skb_rb_last(&sk->tcp_rtx_queue); |
|
if (unlikely(!skb)) { |
|
WARN_ONCE(tp->packets_out, |
|
"invalid inflight: %u state %u cwnd %u mss %d\n", |
|
tp->packets_out, sk->sk_state, tp->snd_cwnd, mss); |
|
inet_csk(sk)->icsk_pending = 0; |
|
return; |
|
} |
|
|
|
if (skb_still_in_host_queue(sk, skb)) |
|
goto rearm_timer; |
|
|
|
pcount = tcp_skb_pcount(skb); |
|
if (WARN_ON(!pcount)) |
|
goto rearm_timer; |
|
|
|
if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { |
|
if (unlikely(tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, |
|
(pcount - 1) * mss, mss, |
|
GFP_ATOMIC))) |
|
goto rearm_timer; |
|
skb = skb_rb_next(skb); |
|
} |
|
|
|
if (WARN_ON(!skb || !tcp_skb_pcount(skb))) |
|
goto rearm_timer; |
|
|
|
if (__tcp_retransmit_skb(sk, skb, 1)) |
|
goto rearm_timer; |
|
|
|
tp->tlp_retrans = 1; |
|
|
|
probe_sent: |
|
/* Record snd_nxt for loss detection. */ |
|
tp->tlp_high_seq = tp->snd_nxt; |
|
|
|
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSSPROBES); |
|
/* Reset s.t. tcp_rearm_rto will restart timer from now */ |
|
inet_csk(sk)->icsk_pending = 0; |
|
rearm_timer: |
|
tcp_rearm_rto(sk); |
|
} |
|
|
|
/* Push out any pending frames which were held back due to |
|
* TCP_CORK or attempt at coalescing tiny packets. |
|
* The socket must be locked by the caller. |
|
*/ |
|
void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, |
|
int nonagle) |
|
{ |
|
/* If we are closed, the bytes will have to remain here. |
|
* In time closedown will finish, we empty the write queue and |
|
* all will be happy. |
|
*/ |
|
if (unlikely(sk->sk_state == TCP_CLOSE)) |
|
return; |
|
|
|
if (tcp_write_xmit(sk, cur_mss, nonagle, 0, |
|
sk_gfp_mask(sk, GFP_ATOMIC))) |
|
tcp_check_probe_timer(sk); |
|
} |
|
|
|
/* Send _single_ skb sitting at the send head. This function requires |
|
* true push pending frames to setup probe timer etc. |
|
*/ |
|
void tcp_push_one(struct sock *sk, unsigned int mss_now) |
|
{ |
|
struct sk_buff *skb = tcp_send_head(sk); |
|
|
|
BUG_ON(!skb || skb->len < mss_now); |
|
|
|
tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); |
|
} |
|
|
|
/* This function returns the amount that we can raise the |
|
* usable window based on the following constraints |
|
* |
|
* 1. The window can never be shrunk once it is offered (RFC 793) |
|
* 2. We limit memory per socket |
|
* |
|
* RFC 1122: |
|
* "the suggested [SWS] avoidance algorithm for the receiver is to keep |
|
* RECV.NEXT + RCV.WIN fixed until: |
|
* RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" |
|
* |
|
* i.e. don't raise the right edge of the window until you can raise |
|
* it at least MSS bytes. |
|
* |
|
* Unfortunately, the recommended algorithm breaks header prediction, |
|
* since header prediction assumes th->window stays fixed. |
|
* |
|
* Strictly speaking, keeping th->window fixed violates the receiver |
|
* side SWS prevention criteria. The problem is that under this rule |
|
* a stream of single byte packets will cause the right side of the |
|
* window to always advance by a single byte. |
|
* |
|
* Of course, if the sender implements sender side SWS prevention |
|
* then this will not be a problem. |
|
* |
|
* BSD seems to make the following compromise: |
|
* |
|
* If the free space is less than the 1/4 of the maximum |
|
* space available and the free space is less than 1/2 mss, |
|
* then set the window to 0. |
|
* [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] |
|
* Otherwise, just prevent the window from shrinking |
|
* and from being larger than the largest representable value. |
|
* |
|
* This prevents incremental opening of the window in the regime |
|
* where TCP is limited by the speed of the reader side taking |
|
* data out of the TCP receive queue. It does nothing about |
|
* those cases where the window is constrained on the sender side |
|
* because the pipeline is full. |
|
* |
|
* BSD also seems to "accidentally" limit itself to windows that are a |
|
* multiple of MSS, at least until the free space gets quite small. |
|
* This would appear to be a side effect of the mbuf implementation. |
|
* Combining these two algorithms results in the observed behavior |
|
* of having a fixed window size at almost all times. |
|
* |
|
* Below we obtain similar behavior by forcing the offered window to |
|
* a multiple of the mss when it is feasible to do so. |
|
* |
|
* Note, we don't "adjust" for TIMESTAMP or SACK option bytes. |
|
* Regular options like TIMESTAMP are taken into account. |
|
*/ |
|
u32 __tcp_select_window(struct sock *sk) |
|
{ |
|
struct inet_connection_sock *icsk = inet_csk(sk); |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
/* MSS for the peer's data. Previous versions used mss_clamp |
|
* here. I don't know if the value based on our guesses |
|
* of peer's MSS is better for the performance. It's more correct |
|
* but may be worse for the performance because of rcv_mss |
|
* fluctuations. --SAW 1998/11/1 |
|
*/ |
|
int mss = icsk->icsk_ack.rcv_mss; |
|
int free_space = tcp_space(sk); |
|
int allowed_space = tcp_full_space(sk); |
|
int full_space, window; |
|
|
|
if (sk_is_mptcp(sk)) |
|
mptcp_space(sk, &free_space, &allowed_space); |
|
|
|
full_space = min_t(int, tp->window_clamp, allowed_space); |
|
|
|
if (unlikely(mss > full_space)) { |
|
mss = full_space; |
|
if (mss <= 0) |
|
return 0; |
|
} |
|
if (free_space < (full_space >> 1)) { |
|
icsk->icsk_ack.quick = 0; |
|
|
|
if (tcp_under_memory_pressure(sk)) |
|
tp->rcv_ssthresh = min(tp->rcv_ssthresh, |
|
4U * tp->advmss); |
|
|
|
/* free_space might become our new window, make sure we don't |
|
* increase it due to wscale. |
|
*/ |
|
free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); |
|
|
|
/* if free space is less than mss estimate, or is below 1/16th |
|
* of the maximum allowed, try to move to zero-window, else |
|
* tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and |
|
* new incoming data is dropped due to memory limits. |
|
* With large window, mss test triggers way too late in order |
|
* to announce zero window in time before rmem limit kicks in. |
|
*/ |
|
if (free_space < (allowed_space >> 4) || free_space < mss) |
|
return 0; |
|
} |
|
|
|
if (free_space > tp->rcv_ssthresh) |
|
free_space = tp->rcv_ssthresh; |
|
|
|
/* Don't do rounding if we are using window scaling, since the |
|
* scaled window will not line up with the MSS boundary anyway. |
|
*/ |
|
if (tp->rx_opt.rcv_wscale) { |
|
window = free_space; |
|
|
|
/* Advertise enough space so that it won't get scaled away. |
|
* Import case: prevent zero window announcement if |
|
* 1<<rcv_wscale > mss. |
|
*/ |
|
window = ALIGN(window, (1 << tp->rx_opt.rcv_wscale)); |
|
} else { |
|
window = tp->rcv_wnd; |
|
/* Get the largest window that is a nice multiple of mss. |
|
* Window clamp already applied above. |
|
* If our current window offering is within 1 mss of the |
|
* free space we just keep it. This prevents the divide |
|
* and multiply from happening most of the time. |
|
* We also don't do any window rounding when the free space |
|
* is too small. |
|
*/ |
|
if (window <= free_space - mss || window > free_space) |
|
window = rounddown(free_space, mss); |
|
else if (mss == full_space && |
|
free_space > window + (full_space >> 1)) |
|
window = free_space; |
|
} |
|
|
|
return window; |
|
} |
|
|
|
void tcp_skb_collapse_tstamp(struct sk_buff *skb, |
|
const struct sk_buff *next_skb) |
|
{ |
|
if (unlikely(tcp_has_tx_tstamp(next_skb))) { |
|
const struct skb_shared_info *next_shinfo = |
|
skb_shinfo(next_skb); |
|
struct skb_shared_info *shinfo = skb_shinfo(skb); |
|
|
|
shinfo->tx_flags |= next_shinfo->tx_flags & SKBTX_ANY_TSTAMP; |
|
shinfo->tskey = next_shinfo->tskey; |
|
TCP_SKB_CB(skb)->txstamp_ack |= |
|
TCP_SKB_CB(next_skb)->txstamp_ack; |
|
} |
|
} |
|
|
|
/* Collapses two adjacent SKB's during retransmission. */ |
|
static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
struct sk_buff *next_skb = skb_rb_next(skb); |
|
int next_skb_size; |
|
|
|
next_skb_size = next_skb->len; |
|
|
|
BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); |
|
|
|
if (next_skb_size) { |
|
if (next_skb_size <= skb_availroom(skb)) |
|
skb_copy_bits(next_skb, 0, skb_put(skb, next_skb_size), |
|
next_skb_size); |
|
else if (!tcp_skb_shift(skb, next_skb, 1, next_skb_size)) |
|
return false; |
|
} |
|
tcp_highest_sack_replace(sk, next_skb, skb); |
|
|
|
/* Update sequence range on original skb. */ |
|
TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; |
|
|
|
/* Merge over control information. This moves PSH/FIN etc. over */ |
|
TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; |
|
|
|
/* All done, get rid of second SKB and account for it so |
|
* packet counting does not break. |
|
*/ |
|
TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; |
|
TCP_SKB_CB(skb)->eor = TCP_SKB_CB(next_skb)->eor; |
|
|
|
/* changed transmit queue under us so clear hints */ |
|
tcp_clear_retrans_hints_partial(tp); |
|
if (next_skb == tp->retransmit_skb_hint) |
|
tp->retransmit_skb_hint = skb; |
|
|
|
tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); |
|
|
|
tcp_skb_collapse_tstamp(skb, next_skb); |
|
|
|
tcp_rtx_queue_unlink_and_free(next_skb, sk); |
|
return true; |
|
} |
|
|
|
/* Check if coalescing SKBs is legal. */ |
|
static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) |
|
{ |
|
if (tcp_skb_pcount(skb) > 1) |
|
return false; |
|
if (skb_cloned(skb)) |
|
return false; |
|
/* Some heuristics for collapsing over SACK'd could be invented */ |
|
if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) |
|
return false; |
|
|
|
return true; |
|
} |
|
|
|
/* Collapse packets in the retransmit queue to make to create |
|
* less packets on the wire. This is only done on retransmission. |
|
*/ |
|
static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, |
|
int space) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
struct sk_buff *skb = to, *tmp; |
|
bool first = true; |
|
|
|
if (!sock_net(sk)->ipv4.sysctl_tcp_retrans_collapse) |
|
return; |
|
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) |
|
return; |
|
|
|
skb_rbtree_walk_from_safe(skb, tmp) { |
|
if (!tcp_can_collapse(sk, skb)) |
|
break; |
|
|
|
if (!tcp_skb_can_collapse(to, skb)) |
|
break; |
|
|
|
space -= skb->len; |
|
|
|
if (first) { |
|
first = false; |
|
continue; |
|
} |
|
|
|
if (space < 0) |
|
break; |
|
|
|
if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) |
|
break; |
|
|
|
if (!tcp_collapse_retrans(sk, to)) |
|
break; |
|
} |
|
} |
|
|
|
/* This retransmits one SKB. Policy decisions and retransmit queue |
|
* state updates are done by the caller. Returns non-zero if an |
|
* error occurred which prevented the send. |
|
*/ |
|
int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) |
|
{ |
|
struct inet_connection_sock *icsk = inet_csk(sk); |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
unsigned int cur_mss; |
|
int diff, len, err; |
|
|
|
|
|
/* Inconclusive MTU probe */ |
|
if (icsk->icsk_mtup.probe_size) |
|
icsk->icsk_mtup.probe_size = 0; |
|
|
|
/* Do not sent more than we queued. 1/4 is reserved for possible |
|
* copying overhead: fragmentation, tunneling, mangling etc. |
|
*/ |
|
if (refcount_read(&sk->sk_wmem_alloc) > |
|
min_t(u32, sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), |
|
sk->sk_sndbuf)) |
|
return -EAGAIN; |
|
|
|
if (skb_still_in_host_queue(sk, skb)) |
|
return -EBUSY; |
|
|
|
if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { |
|
if (unlikely(before(TCP_SKB_CB(skb)->end_seq, tp->snd_una))) { |
|
WARN_ON_ONCE(1); |
|
return -EINVAL; |
|
} |
|
if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) |
|
return -ENOMEM; |
|
} |
|
|
|
if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) |
|
return -EHOSTUNREACH; /* Routing failure or similar. */ |
|
|
|
cur_mss = tcp_current_mss(sk); |
|
|
|
/* If receiver has shrunk his window, and skb is out of |
|
* new window, do not retransmit it. The exception is the |
|
* case, when window is shrunk to zero. In this case |
|
* our retransmit serves as a zero window probe. |
|
*/ |
|
if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && |
|
TCP_SKB_CB(skb)->seq != tp->snd_una) |
|
return -EAGAIN; |
|
|
|
len = cur_mss * segs; |
|
if (skb->len > len) { |
|
if (tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, len, |
|
cur_mss, GFP_ATOMIC)) |
|
return -ENOMEM; /* We'll try again later. */ |
|
} else { |
|
if (skb_unclone(skb, GFP_ATOMIC)) |
|
return -ENOMEM; |
|
|
|
diff = tcp_skb_pcount(skb); |
|
tcp_set_skb_tso_segs(skb, cur_mss); |
|
diff -= tcp_skb_pcount(skb); |
|
if (diff) |
|
tcp_adjust_pcount(sk, skb, diff); |
|
if (skb->len < cur_mss) |
|
tcp_retrans_try_collapse(sk, skb, cur_mss); |
|
} |
|
|
|
/* RFC3168, section 6.1.1.1. ECN fallback */ |
|
if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN_ECN) == TCPHDR_SYN_ECN) |
|
tcp_ecn_clear_syn(sk, skb); |
|
|
|
/* Update global and local TCP statistics. */ |
|
segs = tcp_skb_pcount(skb); |
|
TCP_ADD_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS, segs); |
|
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) |
|
__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); |
|
tp->total_retrans += segs; |
|
tp->bytes_retrans += skb->len; |
|
|
|
/* make sure skb->data is aligned on arches that require it |
|
* and check if ack-trimming & collapsing extended the headroom |
|
* beyond what csum_start can cover. |
|
*/ |
|
if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || |
|
skb_headroom(skb) >= 0xFFFF)) { |
|
struct sk_buff *nskb; |
|
|
|
tcp_skb_tsorted_save(skb) { |
|
nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC); |
|
if (nskb) { |
|
nskb->dev = NULL; |
|
err = tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC); |
|
} else { |
|
err = -ENOBUFS; |
|
} |
|
} tcp_skb_tsorted_restore(skb); |
|
|
|
if (!err) { |
|
tcp_update_skb_after_send(sk, skb, tp->tcp_wstamp_ns); |
|
tcp_rate_skb_sent(sk, skb); |
|
} |
|
} else { |
|
err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
|
} |
|
|
|
/* To avoid taking spuriously low RTT samples based on a timestamp |
|
* for a transmit that never happened, always mark EVER_RETRANS |
|
*/ |
|
TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; |
|
|
|
if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RETRANS_CB_FLAG)) |
|
tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RETRANS_CB, |
|
TCP_SKB_CB(skb)->seq, segs, err); |
|
|
|
if (likely(!err)) { |
|
trace_tcp_retransmit_skb(sk, skb); |
|
} else if (err != -EBUSY) { |
|
NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL, segs); |
|
} |
|
return err; |
|
} |
|
|
|
int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
int err = __tcp_retransmit_skb(sk, skb, segs); |
|
|
|
if (err == 0) { |
|
#if FASTRETRANS_DEBUG > 0 |
|
if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { |
|
net_dbg_ratelimited("retrans_out leaked\n"); |
|
} |
|
#endif |
|
TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; |
|
tp->retrans_out += tcp_skb_pcount(skb); |
|
} |
|
|
|
/* Save stamp of the first (attempted) retransmit. */ |
|
if (!tp->retrans_stamp) |
|
tp->retrans_stamp = tcp_skb_timestamp(skb); |
|
|
|
if (tp->undo_retrans < 0) |
|
tp->undo_retrans = 0; |
|
tp->undo_retrans += tcp_skb_pcount(skb); |
|
return err; |
|
} |
|
|
|
/* This gets called after a retransmit timeout, and the initially |
|
* retransmitted data is acknowledged. It tries to continue |
|
* resending the rest of the retransmit queue, until either |
|
* we've sent it all or the congestion window limit is reached. |
|
*/ |
|
void tcp_xmit_retransmit_queue(struct sock *sk) |
|
{ |
|
const struct inet_connection_sock *icsk = inet_csk(sk); |
|
struct sk_buff *skb, *rtx_head, *hole = NULL; |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
bool rearm_timer = false; |
|
u32 max_segs; |
|
int mib_idx; |
|
|
|
if (!tp->packets_out) |
|
return; |
|
|
|
rtx_head = tcp_rtx_queue_head(sk); |
|
skb = tp->retransmit_skb_hint ?: rtx_head; |
|
max_segs = tcp_tso_segs(sk, tcp_current_mss(sk)); |
|
skb_rbtree_walk_from(skb) { |
|
__u8 sacked; |
|
int segs; |
|
|
|
if (tcp_pacing_check(sk)) |
|
break; |
|
|
|
/* we could do better than to assign each time */ |
|
if (!hole) |
|
tp->retransmit_skb_hint = skb; |
|
|
|
segs = tp->snd_cwnd - tcp_packets_in_flight(tp); |
|
if (segs <= 0) |
|
break; |
|
sacked = TCP_SKB_CB(skb)->sacked; |
|
/* In case tcp_shift_skb_data() have aggregated large skbs, |
|
* we need to make sure not sending too bigs TSO packets |
|
*/ |
|
segs = min_t(int, segs, max_segs); |
|
|
|
if (tp->retrans_out >= tp->lost_out) { |
|
break; |
|
} else if (!(sacked & TCPCB_LOST)) { |
|
if (!hole && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) |
|
hole = skb; |
|
continue; |
|
|
|
} else { |
|
if (icsk->icsk_ca_state != TCP_CA_Loss) |
|
mib_idx = LINUX_MIB_TCPFASTRETRANS; |
|
else |
|
mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; |
|
} |
|
|
|
if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) |
|
continue; |
|
|
|
if (tcp_small_queue_check(sk, skb, 1)) |
|
break; |
|
|
|
if (tcp_retransmit_skb(sk, skb, segs)) |
|
break; |
|
|
|
NET_ADD_STATS(sock_net(sk), mib_idx, tcp_skb_pcount(skb)); |
|
|
|
if (tcp_in_cwnd_reduction(sk)) |
|
tp->prr_out += tcp_skb_pcount(skb); |
|
|
|
if (skb == rtx_head && |
|
icsk->icsk_pending != ICSK_TIME_REO_TIMEOUT) |
|
rearm_timer = true; |
|
|
|
} |
|
if (rearm_timer) |
|
tcp_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
|
inet_csk(sk)->icsk_rto, |
|
TCP_RTO_MAX); |
|
} |
|
|
|
/* We allow to exceed memory limits for FIN packets to expedite |
|
* connection tear down and (memory) recovery. |
|
* Otherwise tcp_send_fin() could be tempted to either delay FIN |
|
* or even be forced to close flow without any FIN. |
|
* In general, we want to allow one skb per socket to avoid hangs |
|
* with edge trigger epoll() |
|
*/ |
|
void sk_forced_mem_schedule(struct sock *sk, int size) |
|
{ |
|
int amt; |
|
|
|
if (size <= sk->sk_forward_alloc) |
|
return; |
|
amt = sk_mem_pages(size); |
|
sk->sk_forward_alloc += amt * SK_MEM_QUANTUM; |
|
sk_memory_allocated_add(sk, amt); |
|
|
|
if (mem_cgroup_sockets_enabled && sk->sk_memcg) |
|
mem_cgroup_charge_skmem(sk->sk_memcg, amt); |
|
} |
|
|
|
/* Send a FIN. The caller locks the socket for us. |
|
* We should try to send a FIN packet really hard, but eventually give up. |
|
*/ |
|
void tcp_send_fin(struct sock *sk) |
|
{ |
|
struct sk_buff *skb, *tskb, *tail = tcp_write_queue_tail(sk); |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
|
|
/* Optimization, tack on the FIN if we have one skb in write queue and |
|
* this skb was not yet sent, or we are under memory pressure. |
|
* Note: in the latter case, FIN packet will be sent after a timeout, |
|
* as TCP stack thinks it has already been transmitted. |
|
*/ |
|
tskb = tail; |
|
if (!tskb && tcp_under_memory_pressure(sk)) |
|
tskb = skb_rb_last(&sk->tcp_rtx_queue); |
|
|
|
if (tskb) { |
|
TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN; |
|
TCP_SKB_CB(tskb)->end_seq++; |
|
tp->write_seq++; |
|
if (!tail) { |
|
/* This means tskb was already sent. |
|
* Pretend we included the FIN on previous transmit. |
|
* We need to set tp->snd_nxt to the value it would have |
|
* if FIN had been sent. This is because retransmit path |
|
* does not change tp->snd_nxt. |
|
*/ |
|
WRITE_ONCE(tp->snd_nxt, tp->snd_nxt + 1); |
|
return; |
|
} |
|
} else { |
|
skb = alloc_skb_fclone(MAX_TCP_HEADER, sk->sk_allocation); |
|
if (unlikely(!skb)) |
|
return; |
|
|
|
INIT_LIST_HEAD(&skb->tcp_tsorted_anchor); |
|
skb_reserve(skb, MAX_TCP_HEADER); |
|
sk_forced_mem_schedule(sk, skb->truesize); |
|
/* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ |
|
tcp_init_nondata_skb(skb, tp->write_seq, |
|
TCPHDR_ACK | TCPHDR_FIN); |
|
tcp_queue_skb(sk, skb); |
|
} |
|
__tcp_push_pending_frames(sk, tcp_current_mss(sk), TCP_NAGLE_OFF); |
|
} |
|
|
|
/* We get here when a process closes a file descriptor (either due to |
|
* an explicit close() or as a byproduct of exit()'ing) and there |
|
* was unread data in the receive queue. This behavior is recommended |
|
* by RFC 2525, section 2.17. -DaveM |
|
*/ |
|
void tcp_send_active_reset(struct sock *sk, gfp_t priority) |
|
{ |
|
struct sk_buff *skb; |
|
|
|
TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); |
|
|
|
/* NOTE: No TCP options attached and we never retransmit this. */ |
|
skb = alloc_skb(MAX_TCP_HEADER, priority); |
|
if (!skb) { |
|
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); |
|
return; |
|
} |
|
|
|
/* Reserve space for headers and prepare control bits. */ |
|
skb_reserve(skb, MAX_TCP_HEADER); |
|
tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), |
|
TCPHDR_ACK | TCPHDR_RST); |
|
tcp_mstamp_refresh(tcp_sk(sk)); |
|
/* Send it off. */ |
|
if (tcp_transmit_skb(sk, skb, 0, priority)) |
|
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); |
|
|
|
/* skb of trace_tcp_send_reset() keeps the skb that caused RST, |
|
* skb here is different to the troublesome skb, so use NULL |
|
*/ |
|
trace_tcp_send_reset(sk, NULL); |
|
} |
|
|
|
/* Send a crossed SYN-ACK during socket establishment. |
|
* WARNING: This routine must only be called when we have already sent |
|
* a SYN packet that crossed the incoming SYN that caused this routine |
|
* to get called. If this assumption fails then the initial rcv_wnd |
|
* and rcv_wscale values will not be correct. |
|
*/ |
|
int tcp_send_synack(struct sock *sk) |
|
{ |
|
struct sk_buff *skb; |
|
|
|
skb = tcp_rtx_queue_head(sk); |
|
if (!skb || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { |
|
pr_err("%s: wrong queue state\n", __func__); |
|
return -EFAULT; |
|
} |
|
if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { |
|
if (skb_cloned(skb)) { |
|
struct sk_buff *nskb; |
|
|
|
tcp_skb_tsorted_save(skb) { |
|
nskb = skb_copy(skb, GFP_ATOMIC); |
|
} tcp_skb_tsorted_restore(skb); |
|
if (!nskb) |
|
return -ENOMEM; |
|
INIT_LIST_HEAD(&nskb->tcp_tsorted_anchor); |
|
tcp_highest_sack_replace(sk, skb, nskb); |
|
tcp_rtx_queue_unlink_and_free(skb, sk); |
|
__skb_header_release(nskb); |
|
tcp_rbtree_insert(&sk->tcp_rtx_queue, nskb); |
|
sk_wmem_queued_add(sk, nskb->truesize); |
|
sk_mem_charge(sk, nskb->truesize); |
|
skb = nskb; |
|
} |
|
|
|
TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; |
|
tcp_ecn_send_synack(sk, skb); |
|
} |
|
return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
|
} |
|
|
|
/** |
|
* tcp_make_synack - Allocate one skb and build a SYNACK packet. |
|
* @sk: listener socket |
|
* @dst: dst entry attached to the SYNACK. It is consumed and caller |
|
* should not use it again. |
|
* @req: request_sock pointer |
|
* @foc: cookie for tcp fast open |
|
* @synack_type: Type of synack to prepare |
|
* @syn_skb: SYN packet just received. It could be NULL for rtx case. |
|
*/ |
|
struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, |
|
struct request_sock *req, |
|
struct tcp_fastopen_cookie *foc, |
|
enum tcp_synack_type synack_type, |
|
struct sk_buff *syn_skb) |
|
{ |
|
struct inet_request_sock *ireq = inet_rsk(req); |
|
const struct tcp_sock *tp = tcp_sk(sk); |
|
struct tcp_md5sig_key *md5 = NULL; |
|
struct tcp_out_options opts; |
|
struct sk_buff *skb; |
|
int tcp_header_size; |
|
struct tcphdr *th; |
|
int mss; |
|
u64 now; |
|
|
|
skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); |
|
if (unlikely(!skb)) { |
|
dst_release(dst); |
|
return NULL; |
|
} |
|
/* Reserve space for headers. */ |
|
skb_reserve(skb, MAX_TCP_HEADER); |
|
|
|
switch (synack_type) { |
|
case TCP_SYNACK_NORMAL: |
|
skb_set_owner_w(skb, req_to_sk(req)); |
|
break; |
|
case TCP_SYNACK_COOKIE: |
|
/* Under synflood, we do not attach skb to a socket, |
|
* to avoid false sharing. |
|
*/ |
|
break; |
|
case TCP_SYNACK_FASTOPEN: |
|
/* sk is a const pointer, because we want to express multiple |
|
* cpu might call us concurrently. |
|
* sk->sk_wmem_alloc in an atomic, we can promote to rw. |
|
*/ |
|
skb_set_owner_w(skb, (struct sock *)sk); |
|
break; |
|
} |
|
skb_dst_set(skb, dst); |
|
|
|
mss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); |
|
|
|
memset(&opts, 0, sizeof(opts)); |
|
now = tcp_clock_ns(); |
|
#ifdef CONFIG_SYN_COOKIES |
|
if (unlikely(synack_type == TCP_SYNACK_COOKIE && ireq->tstamp_ok)) |
|
skb->skb_mstamp_ns = cookie_init_timestamp(req, now); |
|
else |
|
#endif |
|
{ |
|
skb->skb_mstamp_ns = now; |
|
if (!tcp_rsk(req)->snt_synack) /* Timestamp first SYNACK */ |
|
tcp_rsk(req)->snt_synack = tcp_skb_timestamp_us(skb); |
|
} |
|
|
|
#ifdef CONFIG_TCP_MD5SIG |
|
rcu_read_lock(); |
|
md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req)); |
|
#endif |
|
skb_set_hash(skb, tcp_rsk(req)->txhash, PKT_HASH_TYPE_L4); |
|
/* bpf program will be interested in the tcp_flags */ |
|
TCP_SKB_CB(skb)->tcp_flags = TCPHDR_SYN | TCPHDR_ACK; |
|
tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, md5, |
|
foc, synack_type, |
|
syn_skb) + sizeof(*th); |
|
|
|
skb_push(skb, tcp_header_size); |
|
skb_reset_transport_header(skb); |
|
|
|
th = (struct tcphdr *)skb->data; |
|
memset(th, 0, sizeof(struct tcphdr)); |
|
th->syn = 1; |
|
th->ack = 1; |
|
tcp_ecn_make_synack(req, th); |
|
th->source = htons(ireq->ir_num); |
|
th->dest = ireq->ir_rmt_port; |
|
skb->mark = ireq->ir_mark; |
|
skb->ip_summed = CHECKSUM_PARTIAL; |
|
th->seq = htonl(tcp_rsk(req)->snt_isn); |
|
/* XXX data is queued and acked as is. No buffer/window check */ |
|
th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); |
|
|
|
/* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ |
|
th->window = htons(min(req->rsk_rcv_wnd, 65535U)); |
|
tcp_options_write((__be32 *)(th + 1), NULL, &opts); |
|
th->doff = (tcp_header_size >> 2); |
|
__TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS); |
|
|
|
#ifdef CONFIG_TCP_MD5SIG |
|
/* Okay, we have all we need - do the md5 hash if needed */ |
|
if (md5) |
|
tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, |
|
md5, req_to_sk(req), skb); |
|
rcu_read_unlock(); |
|
#endif |
|
|
|
bpf_skops_write_hdr_opt((struct sock *)sk, skb, req, syn_skb, |
|
synack_type, &opts); |
|
|
|
skb->skb_mstamp_ns = now; |
|
tcp_add_tx_delay(skb, tp); |
|
|
|
return skb; |
|
} |
|
EXPORT_SYMBOL(tcp_make_synack); |
|
|
|
static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst) |
|
{ |
|
struct inet_connection_sock *icsk = inet_csk(sk); |
|
const struct tcp_congestion_ops *ca; |
|
u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); |
|
|
|
if (ca_key == TCP_CA_UNSPEC) |
|
return; |
|
|
|
rcu_read_lock(); |
|
ca = tcp_ca_find_key(ca_key); |
|
if (likely(ca && bpf_try_module_get(ca, ca->owner))) { |
|
bpf_module_put(icsk->icsk_ca_ops, icsk->icsk_ca_ops->owner); |
|
icsk->icsk_ca_dst_locked = tcp_ca_dst_locked(dst); |
|
icsk->icsk_ca_ops = ca; |
|
} |
|
rcu_read_unlock(); |
|
} |
|
|
|
/* Do all connect socket setups that can be done AF independent. */ |
|
static void tcp_connect_init(struct sock *sk) |
|
{ |
|
const struct dst_entry *dst = __sk_dst_get(sk); |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
__u8 rcv_wscale; |
|
u32 rcv_wnd; |
|
|
|
/* We'll fix this up when we get a response from the other end. |
|
* See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. |
|
*/ |
|
tp->tcp_header_len = sizeof(struct tcphdr); |
|
if (sock_net(sk)->ipv4.sysctl_tcp_timestamps) |
|
tp->tcp_header_len += TCPOLEN_TSTAMP_ALIGNED; |
|
|
|
#ifdef CONFIG_TCP_MD5SIG |
|
if (tp->af_specific->md5_lookup(sk, sk)) |
|
tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; |
|
#endif |
|
|
|
/* If user gave his TCP_MAXSEG, record it to clamp */ |
|
if (tp->rx_opt.user_mss) |
|
tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; |
|
tp->max_window = 0; |
|
tcp_mtup_init(sk); |
|
tcp_sync_mss(sk, dst_mtu(dst)); |
|
|
|
tcp_ca_dst_init(sk, dst); |
|
|
|
if (!tp->window_clamp) |
|
tp->window_clamp = dst_metric(dst, RTAX_WINDOW); |
|
tp->advmss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); |
|
|
|
tcp_initialize_rcv_mss(sk); |
|
|
|
/* limit the window selection if the user enforce a smaller rx buffer */ |
|
if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && |
|
(tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) |
|
tp->window_clamp = tcp_full_space(sk); |
|
|
|
rcv_wnd = tcp_rwnd_init_bpf(sk); |
|
if (rcv_wnd == 0) |
|
rcv_wnd = dst_metric(dst, RTAX_INITRWND); |
|
|
|
tcp_select_initial_window(sk, tcp_full_space(sk), |
|
tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), |
|
&tp->rcv_wnd, |
|
&tp->window_clamp, |
|
sock_net(sk)->ipv4.sysctl_tcp_window_scaling, |
|
&rcv_wscale, |
|
rcv_wnd); |
|
|
|
tp->rx_opt.rcv_wscale = rcv_wscale; |
|
tp->rcv_ssthresh = tp->rcv_wnd; |
|
|
|
sk->sk_err = 0; |
|
sock_reset_flag(sk, SOCK_DONE); |
|
tp->snd_wnd = 0; |
|
tcp_init_wl(tp, 0); |
|
tcp_write_queue_purge(sk); |
|
tp->snd_una = tp->write_seq; |
|
tp->snd_sml = tp->write_seq; |
|
tp->snd_up = tp->write_seq; |
|
WRITE_ONCE(tp->snd_nxt, tp->write_seq); |
|
|
|
if (likely(!tp->repair)) |
|
tp->rcv_nxt = 0; |
|
else |
|
tp->rcv_tstamp = tcp_jiffies32; |
|
tp->rcv_wup = tp->rcv_nxt; |
|
WRITE_ONCE(tp->copied_seq, tp->rcv_nxt); |
|
|
|
inet_csk(sk)->icsk_rto = tcp_timeout_init(sk); |
|
inet_csk(sk)->icsk_retransmits = 0; |
|
tcp_clear_retrans(tp); |
|
} |
|
|
|
static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); |
|
|
|
tcb->end_seq += skb->len; |
|
__skb_header_release(skb); |
|
sk_wmem_queued_add(sk, skb->truesize); |
|
sk_mem_charge(sk, skb->truesize); |
|
WRITE_ONCE(tp->write_seq, tcb->end_seq); |
|
tp->packets_out += tcp_skb_pcount(skb); |
|
} |
|
|
|
/* Build and send a SYN with data and (cached) Fast Open cookie. However, |
|
* queue a data-only packet after the regular SYN, such that regular SYNs |
|
* are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges |
|
* only the SYN sequence, the data are retransmitted in the first ACK. |
|
* If cookie is not cached or other error occurs, falls back to send a |
|
* regular SYN with Fast Open cookie request option. |
|
*/ |
|
static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
struct tcp_fastopen_request *fo = tp->fastopen_req; |
|
int space, err = 0; |
|
struct sk_buff *syn_data; |
|
|
|
tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ |
|
if (!tcp_fastopen_cookie_check(sk, &tp->rx_opt.mss_clamp, &fo->cookie)) |
|
goto fallback; |
|
|
|
/* MSS for SYN-data is based on cached MSS and bounded by PMTU and |
|
* user-MSS. Reserve maximum option space for middleboxes that add |
|
* private TCP options. The cost is reduced data space in SYN :( |
|
*/ |
|
tp->rx_opt.mss_clamp = tcp_mss_clamp(tp, tp->rx_opt.mss_clamp); |
|
|
|
space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) - |
|
MAX_TCP_OPTION_SPACE; |
|
|
|
space = min_t(size_t, space, fo->size); |
|
|
|
/* limit to order-0 allocations */ |
|
space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER)); |
|
|
|
syn_data = sk_stream_alloc_skb(sk, space, sk->sk_allocation, false); |
|
if (!syn_data) |
|
goto fallback; |
|
syn_data->ip_summed = CHECKSUM_PARTIAL; |
|
memcpy(syn_data->cb, syn->cb, sizeof(syn->cb)); |
|
if (space) { |
|
int copied = copy_from_iter(skb_put(syn_data, space), space, |
|
&fo->data->msg_iter); |
|
if (unlikely(!copied)) { |
|
tcp_skb_tsorted_anchor_cleanup(syn_data); |
|
kfree_skb(syn_data); |
|
goto fallback; |
|
} |
|
if (copied != space) { |
|
skb_trim(syn_data, copied); |
|
space = copied; |
|
} |
|
skb_zcopy_set(syn_data, fo->uarg, NULL); |
|
} |
|
/* No more data pending in inet_wait_for_connect() */ |
|
if (space == fo->size) |
|
fo->data = NULL; |
|
fo->copied = space; |
|
|
|
tcp_connect_queue_skb(sk, syn_data); |
|
if (syn_data->len) |
|
tcp_chrono_start(sk, TCP_CHRONO_BUSY); |
|
|
|
err = tcp_transmit_skb(sk, syn_data, 1, sk->sk_allocation); |
|
|
|
syn->skb_mstamp_ns = syn_data->skb_mstamp_ns; |
|
|
|
/* Now full SYN+DATA was cloned and sent (or not), |
|
* remove the SYN from the original skb (syn_data) |
|
* we keep in write queue in case of a retransmit, as we |
|
* also have the SYN packet (with no data) in the same queue. |
|
*/ |
|
TCP_SKB_CB(syn_data)->seq++; |
|
TCP_SKB_CB(syn_data)->tcp_flags = TCPHDR_ACK | TCPHDR_PSH; |
|
if (!err) { |
|
tp->syn_data = (fo->copied > 0); |
|
tcp_rbtree_insert(&sk->tcp_rtx_queue, syn_data); |
|
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT); |
|
goto done; |
|
} |
|
|
|
/* data was not sent, put it in write_queue */ |
|
__skb_queue_tail(&sk->sk_write_queue, syn_data); |
|
tp->packets_out -= tcp_skb_pcount(syn_data); |
|
|
|
fallback: |
|
/* Send a regular SYN with Fast Open cookie request option */ |
|
if (fo->cookie.len > 0) |
|
fo->cookie.len = 0; |
|
err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); |
|
if (err) |
|
tp->syn_fastopen = 0; |
|
done: |
|
fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ |
|
return err; |
|
} |
|
|
|
/* Build a SYN and send it off. */ |
|
int tcp_connect(struct sock *sk) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
struct sk_buff *buff; |
|
int err; |
|
|
|
tcp_call_bpf(sk, BPF_SOCK_OPS_TCP_CONNECT_CB, 0, NULL); |
|
|
|
if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) |
|
return -EHOSTUNREACH; /* Routing failure or similar. */ |
|
|
|
tcp_connect_init(sk); |
|
|
|
if (unlikely(tp->repair)) { |
|
tcp_finish_connect(sk, NULL); |
|
return 0; |
|
} |
|
|
|
buff = sk_stream_alloc_skb(sk, 0, sk->sk_allocation, true); |
|
if (unlikely(!buff)) |
|
return -ENOBUFS; |
|
|
|
tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); |
|
tcp_mstamp_refresh(tp); |
|
tp->retrans_stamp = tcp_time_stamp(tp); |
|
tcp_connect_queue_skb(sk, buff); |
|
tcp_ecn_send_syn(sk, buff); |
|
tcp_rbtree_insert(&sk->tcp_rtx_queue, buff); |
|
|
|
/* Send off SYN; include data in Fast Open. */ |
|
err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : |
|
tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); |
|
if (err == -ECONNREFUSED) |
|
return err; |
|
|
|
/* We change tp->snd_nxt after the tcp_transmit_skb() call |
|
* in order to make this packet get counted in tcpOutSegs. |
|
*/ |
|
WRITE_ONCE(tp->snd_nxt, tp->write_seq); |
|
tp->pushed_seq = tp->write_seq; |
|
buff = tcp_send_head(sk); |
|
if (unlikely(buff)) { |
|
WRITE_ONCE(tp->snd_nxt, TCP_SKB_CB(buff)->seq); |
|
tp->pushed_seq = TCP_SKB_CB(buff)->seq; |
|
} |
|
TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); |
|
|
|
/* Timer for repeating the SYN until an answer. */ |
|
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
|
inet_csk(sk)->icsk_rto, TCP_RTO_MAX); |
|
return 0; |
|
} |
|
EXPORT_SYMBOL(tcp_connect); |
|
|
|
/* Send out a delayed ack, the caller does the policy checking |
|
* to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() |
|
* for details. |
|
*/ |
|
void tcp_send_delayed_ack(struct sock *sk) |
|
{ |
|
struct inet_connection_sock *icsk = inet_csk(sk); |
|
int ato = icsk->icsk_ack.ato; |
|
unsigned long timeout; |
|
|
|
if (ato > TCP_DELACK_MIN) { |
|
const struct tcp_sock *tp = tcp_sk(sk); |
|
int max_ato = HZ / 2; |
|
|
|
if (inet_csk_in_pingpong_mode(sk) || |
|
(icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) |
|
max_ato = TCP_DELACK_MAX; |
|
|
|
/* Slow path, intersegment interval is "high". */ |
|
|
|
/* If some rtt estimate is known, use it to bound delayed ack. |
|
* Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements |
|
* directly. |
|
*/ |
|
if (tp->srtt_us) { |
|
int rtt = max_t(int, usecs_to_jiffies(tp->srtt_us >> 3), |
|
TCP_DELACK_MIN); |
|
|
|
if (rtt < max_ato) |
|
max_ato = rtt; |
|
} |
|
|
|
ato = min(ato, max_ato); |
|
} |
|
|
|
ato = min_t(u32, ato, inet_csk(sk)->icsk_delack_max); |
|
|
|
/* Stay within the limit we were given */ |
|
timeout = jiffies + ato; |
|
|
|
/* Use new timeout only if there wasn't a older one earlier. */ |
|
if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { |
|
/* If delack timer is about to expire, send ACK now. */ |
|
if (time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { |
|
tcp_send_ack(sk); |
|
return; |
|
} |
|
|
|
if (!time_before(timeout, icsk->icsk_ack.timeout)) |
|
timeout = icsk->icsk_ack.timeout; |
|
} |
|
icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; |
|
icsk->icsk_ack.timeout = timeout; |
|
sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); |
|
} |
|
|
|
/* This routine sends an ack and also updates the window. */ |
|
void __tcp_send_ack(struct sock *sk, u32 rcv_nxt) |
|
{ |
|
struct sk_buff *buff; |
|
|
|
/* If we have been reset, we may not send again. */ |
|
if (sk->sk_state == TCP_CLOSE) |
|
return; |
|
|
|
/* We are not putting this on the write queue, so |
|
* tcp_transmit_skb() will set the ownership to this |
|
* sock. |
|
*/ |
|
buff = alloc_skb(MAX_TCP_HEADER, |
|
sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); |
|
if (unlikely(!buff)) { |
|
struct inet_connection_sock *icsk = inet_csk(sk); |
|
unsigned long delay; |
|
|
|
delay = TCP_DELACK_MAX << icsk->icsk_ack.retry; |
|
if (delay < TCP_RTO_MAX) |
|
icsk->icsk_ack.retry++; |
|
inet_csk_schedule_ack(sk); |
|
icsk->icsk_ack.ato = TCP_ATO_MIN; |
|
inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, delay, TCP_RTO_MAX); |
|
return; |
|
} |
|
|
|
/* Reserve space for headers and prepare control bits. */ |
|
skb_reserve(buff, MAX_TCP_HEADER); |
|
tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); |
|
|
|
/* We do not want pure acks influencing TCP Small Queues or fq/pacing |
|
* too much. |
|
* SKB_TRUESIZE(max(1 .. 66, MAX_TCP_HEADER)) is unfortunately ~784 |
|
*/ |
|
skb_set_tcp_pure_ack(buff); |
|
|
|
/* Send it off, this clears delayed acks for us. */ |
|
__tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0, rcv_nxt); |
|
} |
|
EXPORT_SYMBOL_GPL(__tcp_send_ack); |
|
|
|
void tcp_send_ack(struct sock *sk) |
|
{ |
|
__tcp_send_ack(sk, tcp_sk(sk)->rcv_nxt); |
|
} |
|
|
|
/* This routine sends a packet with an out of date sequence |
|
* number. It assumes the other end will try to ack it. |
|
* |
|
* Question: what should we make while urgent mode? |
|
* 4.4BSD forces sending single byte of data. We cannot send |
|
* out of window data, because we have SND.NXT==SND.MAX... |
|
* |
|
* Current solution: to send TWO zero-length segments in urgent mode: |
|
* one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is |
|
* out-of-date with SND.UNA-1 to probe window. |
|
*/ |
|
static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
struct sk_buff *skb; |
|
|
|
/* We don't queue it, tcp_transmit_skb() sets ownership. */ |
|
skb = alloc_skb(MAX_TCP_HEADER, |
|
sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); |
|
if (!skb) |
|
return -1; |
|
|
|
/* Reserve space for headers and set control bits. */ |
|
skb_reserve(skb, MAX_TCP_HEADER); |
|
/* Use a previous sequence. This should cause the other |
|
* end to send an ack. Don't queue or clone SKB, just |
|
* send it. |
|
*/ |
|
tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); |
|
NET_INC_STATS(sock_net(sk), mib); |
|
return tcp_transmit_skb(sk, skb, 0, (__force gfp_t)0); |
|
} |
|
|
|
/* Called from setsockopt( ... TCP_REPAIR ) */ |
|
void tcp_send_window_probe(struct sock *sk) |
|
{ |
|
if (sk->sk_state == TCP_ESTABLISHED) { |
|
tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; |
|
tcp_mstamp_refresh(tcp_sk(sk)); |
|
tcp_xmit_probe_skb(sk, 0, LINUX_MIB_TCPWINPROBE); |
|
} |
|
} |
|
|
|
/* Initiate keepalive or window probe from timer. */ |
|
int tcp_write_wakeup(struct sock *sk, int mib) |
|
{ |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
struct sk_buff *skb; |
|
|
|
if (sk->sk_state == TCP_CLOSE) |
|
return -1; |
|
|
|
skb = tcp_send_head(sk); |
|
if (skb && before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { |
|
int err; |
|
unsigned int mss = tcp_current_mss(sk); |
|
unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
|
|
|
if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) |
|
tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; |
|
|
|
/* We are probing the opening of a window |
|
* but the window size is != 0 |
|
* must have been a result SWS avoidance ( sender ) |
|
*/ |
|
if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || |
|
skb->len > mss) { |
|
seg_size = min(seg_size, mss); |
|
TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; |
|
if (tcp_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE, |
|
skb, seg_size, mss, GFP_ATOMIC)) |
|
return -1; |
|
} else if (!tcp_skb_pcount(skb)) |
|
tcp_set_skb_tso_segs(skb, mss); |
|
|
|
TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; |
|
err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
|
if (!err) |
|
tcp_event_new_data_sent(sk, skb); |
|
return err; |
|
} else { |
|
if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) |
|
tcp_xmit_probe_skb(sk, 1, mib); |
|
return tcp_xmit_probe_skb(sk, 0, mib); |
|
} |
|
} |
|
|
|
/* A window probe timeout has occurred. If window is not closed send |
|
* a partial packet else a zero probe. |
|
*/ |
|
void tcp_send_probe0(struct sock *sk) |
|
{ |
|
struct inet_connection_sock *icsk = inet_csk(sk); |
|
struct tcp_sock *tp = tcp_sk(sk); |
|
struct net *net = sock_net(sk); |
|
unsigned long timeout; |
|
int err; |
|
|
|
err = tcp_write_wakeup(sk, LINUX_MIB_TCPWINPROBE); |
|
|
|
if (tp->packets_out || tcp_write_queue_empty(sk)) { |
|
/* Cancel probe timer, if it is not required. */ |
|
icsk->icsk_probes_out = 0; |
|
icsk->icsk_backoff = 0; |
|
icsk->icsk_probes_tstamp = 0; |
|
return; |
|
} |
|
|
|
icsk->icsk_probes_out++; |
|
if (err <= 0) { |
|
if (icsk->icsk_backoff < net->ipv4.sysctl_tcp_retries2) |
|
icsk->icsk_backoff++; |
|
timeout = tcp_probe0_when(sk, TCP_RTO_MAX); |
|
} else { |
|
/* If packet was not sent due to local congestion, |
|
* Let senders fight for local resources conservatively. |
|
*/ |
|
timeout = TCP_RESOURCE_PROBE_INTERVAL; |
|
} |
|
|
|
timeout = tcp_clamp_probe0_to_user_timeout(sk, timeout); |
|
tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, timeout, TCP_RTO_MAX); |
|
} |
|
|
|
int tcp_rtx_synack(const struct sock *sk, struct request_sock *req) |
|
{ |
|
const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific; |
|
struct flowi fl; |
|
int res; |
|
|
|
tcp_rsk(req)->txhash = net_tx_rndhash(); |
|
res = af_ops->send_synack(sk, NULL, &fl, req, NULL, TCP_SYNACK_NORMAL, |
|
NULL); |
|
if (!res) { |
|
__TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); |
|
__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); |
|
if (unlikely(tcp_passive_fastopen(sk))) |
|
tcp_sk(sk)->total_retrans++; |
|
trace_tcp_retransmit_synack(sk, req); |
|
} |
|
return res; |
|
} |
|
EXPORT_SYMBOL(tcp_rtx_synack);
|
|
|