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645 lines
18 KiB
645 lines
18 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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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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* The Internet Protocol (IP) module. |
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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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* Donald Becker, <[email protected]> |
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* Alan Cox, <[email protected]> |
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* Richard Underwood |
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* Stefan Becker, <[email protected]> |
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* Jorge Cwik, <[email protected]> |
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* Arnt Gulbrandsen, <[email protected]> |
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* |
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* Fixes: |
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* Alan Cox : Commented a couple of minor bits of surplus code |
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* Alan Cox : Undefining IP_FORWARD doesn't include the code |
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* (just stops a compiler warning). |
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* Alan Cox : Frames with >=MAX_ROUTE record routes, strict routes or loose routes |
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* are junked rather than corrupting things. |
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* Alan Cox : Frames to bad broadcast subnets are dumped |
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* We used to process them non broadcast and |
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* boy could that cause havoc. |
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* Alan Cox : ip_forward sets the free flag on the |
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* new frame it queues. Still crap because |
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* it copies the frame but at least it |
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* doesn't eat memory too. |
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* Alan Cox : Generic queue code and memory fixes. |
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* Fred Van Kempen : IP fragment support (borrowed from NET2E) |
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* Gerhard Koerting: Forward fragmented frames correctly. |
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* Gerhard Koerting: Fixes to my fix of the above 8-). |
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* Gerhard Koerting: IP interface addressing fix. |
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* Linus Torvalds : More robustness checks |
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* Alan Cox : Even more checks: Still not as robust as it ought to be |
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* Alan Cox : Save IP header pointer for later |
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* Alan Cox : ip option setting |
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* Alan Cox : Use ip_tos/ip_ttl settings |
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* Alan Cox : Fragmentation bogosity removed |
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* (Thanks to [email protected]) |
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* Dmitry Gorodchanin : Send of a raw packet crash fix. |
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* Alan Cox : Silly ip bug when an overlength |
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* fragment turns up. Now frees the |
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* queue. |
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* Linus Torvalds/ : Memory leakage on fragmentation |
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* Alan Cox : handling. |
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* Gerhard Koerting: Forwarding uses IP priority hints |
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* Teemu Rantanen : Fragment problems. |
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* Alan Cox : General cleanup, comments and reformat |
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* Alan Cox : SNMP statistics |
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* Alan Cox : BSD address rule semantics. Also see |
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* UDP as there is a nasty checksum issue |
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* if you do things the wrong way. |
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* Alan Cox : Always defrag, moved IP_FORWARD to the config.in file |
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* Alan Cox : IP options adjust sk->priority. |
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* Pedro Roque : Fix mtu/length error in ip_forward. |
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* Alan Cox : Avoid ip_chk_addr when possible. |
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* Richard Underwood : IP multicasting. |
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* Alan Cox : Cleaned up multicast handlers. |
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* Alan Cox : RAW sockets demultiplex in the BSD style. |
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* Gunther Mayer : Fix the SNMP reporting typo |
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* Alan Cox : Always in group 224.0.0.1 |
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* Pauline Middelink : Fast ip_checksum update when forwarding |
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* Masquerading support. |
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* Alan Cox : Multicast loopback error for 224.0.0.1 |
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* Alan Cox : IP_MULTICAST_LOOP option. |
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* Alan Cox : Use notifiers. |
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* Bjorn Ekwall : Removed ip_csum (from slhc.c too) |
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* Bjorn Ekwall : Moved ip_fast_csum to ip.h (inline!) |
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* Stefan Becker : Send out ICMP HOST REDIRECT |
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* Arnt Gulbrandsen : ip_build_xmit |
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* Alan Cox : Per socket routing cache |
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* Alan Cox : Fixed routing cache, added header cache. |
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* Alan Cox : Loopback didn't work right in original ip_build_xmit - fixed it. |
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* Alan Cox : Only send ICMP_REDIRECT if src/dest are the same net. |
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* Alan Cox : Incoming IP option handling. |
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* Alan Cox : Set saddr on raw output frames as per BSD. |
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* Alan Cox : Stopped broadcast source route explosions. |
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* Alan Cox : Can disable source routing |
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* Takeshi Sone : Masquerading didn't work. |
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* Dave Bonn,Alan Cox : Faster IP forwarding whenever possible. |
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* Alan Cox : Memory leaks, tramples, misc debugging. |
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* Alan Cox : Fixed multicast (by popular demand 8)) |
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* Alan Cox : Fixed forwarding (by even more popular demand 8)) |
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* Alan Cox : Fixed SNMP statistics [I think] |
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* Gerhard Koerting : IP fragmentation forwarding fix |
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* Alan Cox : Device lock against page fault. |
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* Alan Cox : IP_HDRINCL facility. |
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* Werner Almesberger : Zero fragment bug |
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* Alan Cox : RAW IP frame length bug |
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* Alan Cox : Outgoing firewall on build_xmit |
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* A.N.Kuznetsov : IP_OPTIONS support throughout the kernel |
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* Alan Cox : Multicast routing hooks |
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* Jos Vos : Do accounting *before* call_in_firewall |
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* Willy Konynenberg : Transparent proxying support |
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* |
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* To Fix: |
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* IP fragmentation wants rewriting cleanly. The RFC815 algorithm is much more efficient |
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* and could be made very efficient with the addition of some virtual memory hacks to permit |
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* the allocation of a buffer that can then be 'grown' by twiddling page tables. |
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* Output fragmentation wants updating along with the buffer management to use a single |
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* interleaved copy algorithm so that fragmenting has a one copy overhead. Actual packet |
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* output should probably do its own fragmentation at the UDP/RAW layer. TCP shouldn't cause |
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* fragmentation anyway. |
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*/ |
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|
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#define pr_fmt(fmt) "IPv4: " fmt |
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|
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#include <linux/module.h> |
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#include <linux/types.h> |
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#include <linux/kernel.h> |
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#include <linux/string.h> |
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#include <linux/errno.h> |
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#include <linux/slab.h> |
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#include <linux/net.h> |
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#include <linux/socket.h> |
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#include <linux/sockios.h> |
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#include <linux/in.h> |
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#include <linux/inet.h> |
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#include <linux/inetdevice.h> |
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#include <linux/netdevice.h> |
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#include <linux/etherdevice.h> |
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#include <linux/indirect_call_wrapper.h> |
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|
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#include <net/snmp.h> |
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#include <net/ip.h> |
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#include <net/protocol.h> |
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#include <net/route.h> |
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#include <linux/skbuff.h> |
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#include <net/sock.h> |
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#include <net/arp.h> |
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#include <net/icmp.h> |
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#include <net/raw.h> |
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#include <net/checksum.h> |
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#include <net/inet_ecn.h> |
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#include <linux/netfilter_ipv4.h> |
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#include <net/xfrm.h> |
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#include <linux/mroute.h> |
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#include <linux/netlink.h> |
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#include <net/dst_metadata.h> |
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|
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/* |
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* Process Router Attention IP option (RFC 2113) |
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*/ |
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bool ip_call_ra_chain(struct sk_buff *skb) |
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{ |
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struct ip_ra_chain *ra; |
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u8 protocol = ip_hdr(skb)->protocol; |
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struct sock *last = NULL; |
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struct net_device *dev = skb->dev; |
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struct net *net = dev_net(dev); |
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|
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for (ra = rcu_dereference(net->ipv4.ra_chain); ra; ra = rcu_dereference(ra->next)) { |
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struct sock *sk = ra->sk; |
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|
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/* If socket is bound to an interface, only report |
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* the packet if it came from that interface. |
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*/ |
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if (sk && inet_sk(sk)->inet_num == protocol && |
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(!sk->sk_bound_dev_if || |
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sk->sk_bound_dev_if == dev->ifindex)) { |
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if (ip_is_fragment(ip_hdr(skb))) { |
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if (ip_defrag(net, skb, IP_DEFRAG_CALL_RA_CHAIN)) |
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return true; |
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} |
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if (last) { |
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struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC); |
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if (skb2) |
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raw_rcv(last, skb2); |
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} |
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last = sk; |
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} |
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} |
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|
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if (last) { |
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raw_rcv(last, skb); |
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return true; |
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} |
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return false; |
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} |
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INDIRECT_CALLABLE_DECLARE(int udp_rcv(struct sk_buff *)); |
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INDIRECT_CALLABLE_DECLARE(int tcp_v4_rcv(struct sk_buff *)); |
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void ip_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int protocol) |
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{ |
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const struct net_protocol *ipprot; |
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int raw, ret; |
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resubmit: |
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raw = raw_local_deliver(skb, protocol); |
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ipprot = rcu_dereference(inet_protos[protocol]); |
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if (ipprot) { |
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if (!ipprot->no_policy) { |
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if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { |
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kfree_skb(skb); |
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return; |
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} |
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nf_reset_ct(skb); |
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} |
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ret = INDIRECT_CALL_2(ipprot->handler, tcp_v4_rcv, udp_rcv, |
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skb); |
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if (ret < 0) { |
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protocol = -ret; |
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goto resubmit; |
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} |
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__IP_INC_STATS(net, IPSTATS_MIB_INDELIVERS); |
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} else { |
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if (!raw) { |
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if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { |
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__IP_INC_STATS(net, IPSTATS_MIB_INUNKNOWNPROTOS); |
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icmp_send(skb, ICMP_DEST_UNREACH, |
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ICMP_PROT_UNREACH, 0); |
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} |
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kfree_skb(skb); |
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} else { |
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__IP_INC_STATS(net, IPSTATS_MIB_INDELIVERS); |
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consume_skb(skb); |
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} |
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} |
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} |
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static int ip_local_deliver_finish(struct net *net, struct sock *sk, struct sk_buff *skb) |
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{ |
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__skb_pull(skb, skb_network_header_len(skb)); |
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rcu_read_lock(); |
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ip_protocol_deliver_rcu(net, skb, ip_hdr(skb)->protocol); |
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rcu_read_unlock(); |
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return 0; |
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} |
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/* |
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* Deliver IP Packets to the higher protocol layers. |
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*/ |
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int ip_local_deliver(struct sk_buff *skb) |
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{ |
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/* |
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* Reassemble IP fragments. |
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*/ |
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struct net *net = dev_net(skb->dev); |
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if (ip_is_fragment(ip_hdr(skb))) { |
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if (ip_defrag(net, skb, IP_DEFRAG_LOCAL_DELIVER)) |
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return 0; |
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} |
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return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN, |
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net, NULL, skb, skb->dev, NULL, |
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ip_local_deliver_finish); |
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} |
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EXPORT_SYMBOL(ip_local_deliver); |
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static inline bool ip_rcv_options(struct sk_buff *skb, struct net_device *dev) |
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{ |
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struct ip_options *opt; |
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const struct iphdr *iph; |
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|
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/* It looks as overkill, because not all |
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IP options require packet mangling. |
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But it is the easiest for now, especially taking |
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into account that combination of IP options |
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and running sniffer is extremely rare condition. |
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--ANK (980813) |
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*/ |
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if (skb_cow(skb, skb_headroom(skb))) { |
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__IP_INC_STATS(dev_net(dev), IPSTATS_MIB_INDISCARDS); |
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goto drop; |
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} |
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iph = ip_hdr(skb); |
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opt = &(IPCB(skb)->opt); |
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opt->optlen = iph->ihl*4 - sizeof(struct iphdr); |
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if (ip_options_compile(dev_net(dev), opt, skb)) { |
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__IP_INC_STATS(dev_net(dev), IPSTATS_MIB_INHDRERRORS); |
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goto drop; |
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} |
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if (unlikely(opt->srr)) { |
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struct in_device *in_dev = __in_dev_get_rcu(dev); |
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if (in_dev) { |
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if (!IN_DEV_SOURCE_ROUTE(in_dev)) { |
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if (IN_DEV_LOG_MARTIANS(in_dev)) |
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net_info_ratelimited("source route option %pI4 -> %pI4\n", |
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&iph->saddr, |
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&iph->daddr); |
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goto drop; |
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} |
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} |
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if (ip_options_rcv_srr(skb, dev)) |
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goto drop; |
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} |
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return false; |
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drop: |
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return true; |
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} |
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static bool ip_can_use_hint(const struct sk_buff *skb, const struct iphdr *iph, |
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const struct sk_buff *hint) |
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{ |
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return hint && !skb_dst(skb) && ip_hdr(hint)->daddr == iph->daddr && |
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ip_hdr(hint)->tos == iph->tos; |
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} |
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INDIRECT_CALLABLE_DECLARE(int udp_v4_early_demux(struct sk_buff *)); |
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INDIRECT_CALLABLE_DECLARE(int tcp_v4_early_demux(struct sk_buff *)); |
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static int ip_rcv_finish_core(struct net *net, struct sock *sk, |
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struct sk_buff *skb, struct net_device *dev, |
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const struct sk_buff *hint) |
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{ |
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const struct iphdr *iph = ip_hdr(skb); |
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int (*edemux)(struct sk_buff *skb); |
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struct rtable *rt; |
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int err; |
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if (ip_can_use_hint(skb, iph, hint)) { |
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err = ip_route_use_hint(skb, iph->daddr, iph->saddr, iph->tos, |
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dev, hint); |
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if (unlikely(err)) |
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goto drop_error; |
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} |
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if (net->ipv4.sysctl_ip_early_demux && |
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!skb_dst(skb) && |
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!skb->sk && |
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!ip_is_fragment(iph)) { |
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const struct net_protocol *ipprot; |
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int protocol = iph->protocol; |
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ipprot = rcu_dereference(inet_protos[protocol]); |
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if (ipprot && (edemux = READ_ONCE(ipprot->early_demux))) { |
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err = INDIRECT_CALL_2(edemux, tcp_v4_early_demux, |
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udp_v4_early_demux, skb); |
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if (unlikely(err)) |
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goto drop_error; |
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/* must reload iph, skb->head might have changed */ |
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iph = ip_hdr(skb); |
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} |
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} |
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|
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/* |
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* Initialise the virtual path cache for the packet. It describes |
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* how the packet travels inside Linux networking. |
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*/ |
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if (!skb_valid_dst(skb)) { |
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err = ip_route_input_noref(skb, iph->daddr, iph->saddr, |
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iph->tos, dev); |
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if (unlikely(err)) |
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goto drop_error; |
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} |
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|
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#ifdef CONFIG_IP_ROUTE_CLASSID |
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if (unlikely(skb_dst(skb)->tclassid)) { |
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struct ip_rt_acct *st = this_cpu_ptr(ip_rt_acct); |
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u32 idx = skb_dst(skb)->tclassid; |
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st[idx&0xFF].o_packets++; |
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st[idx&0xFF].o_bytes += skb->len; |
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st[(idx>>16)&0xFF].i_packets++; |
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st[(idx>>16)&0xFF].i_bytes += skb->len; |
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} |
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#endif |
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|
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if (iph->ihl > 5 && ip_rcv_options(skb, dev)) |
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goto drop; |
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|
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rt = skb_rtable(skb); |
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if (rt->rt_type == RTN_MULTICAST) { |
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__IP_UPD_PO_STATS(net, IPSTATS_MIB_INMCAST, skb->len); |
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} else if (rt->rt_type == RTN_BROADCAST) { |
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__IP_UPD_PO_STATS(net, IPSTATS_MIB_INBCAST, skb->len); |
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} else if (skb->pkt_type == PACKET_BROADCAST || |
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skb->pkt_type == PACKET_MULTICAST) { |
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struct in_device *in_dev = __in_dev_get_rcu(dev); |
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|
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/* RFC 1122 3.3.6: |
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* |
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* When a host sends a datagram to a link-layer broadcast |
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* address, the IP destination address MUST be a legal IP |
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* broadcast or IP multicast address. |
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* |
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* A host SHOULD silently discard a datagram that is received |
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* via a link-layer broadcast (see Section 2.4) but does not |
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* specify an IP multicast or broadcast destination address. |
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* |
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* This doesn't explicitly say L2 *broadcast*, but broadcast is |
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* in a way a form of multicast and the most common use case for |
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* this is 802.11 protecting against cross-station spoofing (the |
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* so-called "hole-196" attack) so do it for both. |
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*/ |
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if (in_dev && |
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IN_DEV_ORCONF(in_dev, DROP_UNICAST_IN_L2_MULTICAST)) |
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goto drop; |
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} |
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|
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return NET_RX_SUCCESS; |
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|
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drop: |
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kfree_skb(skb); |
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return NET_RX_DROP; |
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drop_error: |
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if (err == -EXDEV) |
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__NET_INC_STATS(net, LINUX_MIB_IPRPFILTER); |
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goto drop; |
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} |
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static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb) |
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{ |
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struct net_device *dev = skb->dev; |
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int ret; |
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|
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/* if ingress device is enslaved to an L3 master device pass the |
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* skb to its handler for processing |
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*/ |
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skb = l3mdev_ip_rcv(skb); |
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if (!skb) |
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return NET_RX_SUCCESS; |
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|
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ret = ip_rcv_finish_core(net, sk, skb, dev, NULL); |
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if (ret != NET_RX_DROP) |
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ret = dst_input(skb); |
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return ret; |
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} |
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|
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/* |
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* Main IP Receive routine. |
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*/ |
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static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net) |
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{ |
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const struct iphdr *iph; |
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u32 len; |
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|
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/* When the interface is in promisc. mode, drop all the crap |
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* that it receives, do not try to analyse it. |
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*/ |
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if (skb->pkt_type == PACKET_OTHERHOST) |
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goto drop; |
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|
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__IP_UPD_PO_STATS(net, IPSTATS_MIB_IN, skb->len); |
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|
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skb = skb_share_check(skb, GFP_ATOMIC); |
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if (!skb) { |
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__IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS); |
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goto out; |
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} |
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|
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if (!pskb_may_pull(skb, sizeof(struct iphdr))) |
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goto inhdr_error; |
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|
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iph = ip_hdr(skb); |
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|
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/* |
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* RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum. |
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* |
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* Is the datagram acceptable? |
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* |
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* 1. Length at least the size of an ip header |
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* 2. Version of 4 |
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* 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums] |
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* 4. Doesn't have a bogus length |
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*/ |
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|
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if (iph->ihl < 5 || iph->version != 4) |
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goto inhdr_error; |
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|
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BUILD_BUG_ON(IPSTATS_MIB_ECT1PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_1); |
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BUILD_BUG_ON(IPSTATS_MIB_ECT0PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_0); |
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BUILD_BUG_ON(IPSTATS_MIB_CEPKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_CE); |
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__IP_ADD_STATS(net, |
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IPSTATS_MIB_NOECTPKTS + (iph->tos & INET_ECN_MASK), |
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max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs)); |
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|
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if (!pskb_may_pull(skb, iph->ihl*4)) |
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goto inhdr_error; |
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|
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iph = ip_hdr(skb); |
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|
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if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl))) |
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goto csum_error; |
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|
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len = ntohs(iph->tot_len); |
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if (skb->len < len) { |
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__IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS); |
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goto drop; |
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} else if (len < (iph->ihl*4)) |
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goto inhdr_error; |
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|
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/* Our transport medium may have padded the buffer out. Now we know it |
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* is IP we can trim to the true length of the frame. |
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* Note this now means skb->len holds ntohs(iph->tot_len). |
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*/ |
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if (pskb_trim_rcsum(skb, len)) { |
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__IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS); |
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goto drop; |
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} |
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|
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iph = ip_hdr(skb); |
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skb->transport_header = skb->network_header + iph->ihl*4; |
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|
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/* Remove any debris in the socket control block */ |
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memset(IPCB(skb), 0, sizeof(struct inet_skb_parm)); |
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IPCB(skb)->iif = skb->skb_iif; |
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|
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/* Must drop socket now because of tproxy. */ |
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if (!skb_sk_is_prefetched(skb)) |
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skb_orphan(skb); |
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|
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return skb; |
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|
|
csum_error: |
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__IP_INC_STATS(net, IPSTATS_MIB_CSUMERRORS); |
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inhdr_error: |
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__IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS); |
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drop: |
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kfree_skb(skb); |
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out: |
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return NULL; |
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} |
|
|
|
/* |
|
* IP receive entry point |
|
*/ |
|
int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, |
|
struct net_device *orig_dev) |
|
{ |
|
struct net *net = dev_net(dev); |
|
|
|
skb = ip_rcv_core(skb, net); |
|
if (skb == NULL) |
|
return NET_RX_DROP; |
|
|
|
return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, |
|
net, NULL, skb, dev, NULL, |
|
ip_rcv_finish); |
|
} |
|
|
|
static void ip_sublist_rcv_finish(struct list_head *head) |
|
{ |
|
struct sk_buff *skb, *next; |
|
|
|
list_for_each_entry_safe(skb, next, head, list) { |
|
skb_list_del_init(skb); |
|
dst_input(skb); |
|
} |
|
} |
|
|
|
static struct sk_buff *ip_extract_route_hint(const struct net *net, |
|
struct sk_buff *skb, int rt_type) |
|
{ |
|
if (fib4_has_custom_rules(net) || rt_type == RTN_BROADCAST) |
|
return NULL; |
|
|
|
return skb; |
|
} |
|
|
|
static void ip_list_rcv_finish(struct net *net, struct sock *sk, |
|
struct list_head *head) |
|
{ |
|
struct sk_buff *skb, *next, *hint = NULL; |
|
struct dst_entry *curr_dst = NULL; |
|
struct list_head sublist; |
|
|
|
INIT_LIST_HEAD(&sublist); |
|
list_for_each_entry_safe(skb, next, head, list) { |
|
struct net_device *dev = skb->dev; |
|
struct dst_entry *dst; |
|
|
|
skb_list_del_init(skb); |
|
/* if ingress device is enslaved to an L3 master device pass the |
|
* skb to its handler for processing |
|
*/ |
|
skb = l3mdev_ip_rcv(skb); |
|
if (!skb) |
|
continue; |
|
if (ip_rcv_finish_core(net, sk, skb, dev, hint) == NET_RX_DROP) |
|
continue; |
|
|
|
dst = skb_dst(skb); |
|
if (curr_dst != dst) { |
|
hint = ip_extract_route_hint(net, skb, |
|
((struct rtable *)dst)->rt_type); |
|
|
|
/* dispatch old sublist */ |
|
if (!list_empty(&sublist)) |
|
ip_sublist_rcv_finish(&sublist); |
|
/* start new sublist */ |
|
INIT_LIST_HEAD(&sublist); |
|
curr_dst = dst; |
|
} |
|
list_add_tail(&skb->list, &sublist); |
|
} |
|
/* dispatch final sublist */ |
|
ip_sublist_rcv_finish(&sublist); |
|
} |
|
|
|
static void ip_sublist_rcv(struct list_head *head, struct net_device *dev, |
|
struct net *net) |
|
{ |
|
NF_HOOK_LIST(NFPROTO_IPV4, NF_INET_PRE_ROUTING, net, NULL, |
|
head, dev, NULL, ip_rcv_finish); |
|
ip_list_rcv_finish(net, NULL, head); |
|
} |
|
|
|
/* Receive a list of IP packets */ |
|
void ip_list_rcv(struct list_head *head, struct packet_type *pt, |
|
struct net_device *orig_dev) |
|
{ |
|
struct net_device *curr_dev = NULL; |
|
struct net *curr_net = NULL; |
|
struct sk_buff *skb, *next; |
|
struct list_head sublist; |
|
|
|
INIT_LIST_HEAD(&sublist); |
|
list_for_each_entry_safe(skb, next, head, list) { |
|
struct net_device *dev = skb->dev; |
|
struct net *net = dev_net(dev); |
|
|
|
skb_list_del_init(skb); |
|
skb = ip_rcv_core(skb, net); |
|
if (skb == NULL) |
|
continue; |
|
|
|
if (curr_dev != dev || curr_net != net) { |
|
/* dispatch old sublist */ |
|
if (!list_empty(&sublist)) |
|
ip_sublist_rcv(&sublist, curr_dev, curr_net); |
|
/* start new sublist */ |
|
INIT_LIST_HEAD(&sublist); |
|
curr_dev = dev; |
|
curr_net = net; |
|
} |
|
list_add_tail(&skb->list, &sublist); |
|
} |
|
/* dispatch final sublist */ |
|
if (!list_empty(&sublist)) |
|
ip_sublist_rcv(&sublist, curr_dev, curr_net); |
|
}
|
|
|