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611 lines
15 KiB
611 lines
15 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* IPv6 fragment reassembly |
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* Linux INET6 implementation |
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* |
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* Authors: |
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* Pedro Roque <[email protected]> |
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* |
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* Based on: net/ipv4/ip_fragment.c |
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*/ |
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|
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/* |
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* Fixes: |
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* Andi Kleen Make it work with multiple hosts. |
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* More RFC compliance. |
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* |
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* Horst von Brand Add missing #include <linux/string.h> |
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* Alexey Kuznetsov SMP races, threading, cleanup. |
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* Patrick McHardy LRU queue of frag heads for evictor. |
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* Mitsuru KANDA @USAGI Register inet6_protocol{}. |
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* David Stevens and |
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* YOSHIFUJI,H. @USAGI Always remove fragment header to |
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* calculate ICV correctly. |
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*/ |
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|
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#define pr_fmt(fmt) "IPv6: " fmt |
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|
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#include <linux/errno.h> |
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#include <linux/types.h> |
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#include <linux/string.h> |
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#include <linux/socket.h> |
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#include <linux/sockios.h> |
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#include <linux/jiffies.h> |
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#include <linux/net.h> |
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#include <linux/list.h> |
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#include <linux/netdevice.h> |
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#include <linux/in6.h> |
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#include <linux/ipv6.h> |
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#include <linux/icmpv6.h> |
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#include <linux/random.h> |
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#include <linux/jhash.h> |
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#include <linux/skbuff.h> |
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#include <linux/slab.h> |
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#include <linux/export.h> |
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#include <linux/tcp.h> |
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#include <linux/udp.h> |
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|
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#include <net/sock.h> |
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#include <net/snmp.h> |
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|
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#include <net/ipv6.h> |
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#include <net/ip6_route.h> |
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#include <net/protocol.h> |
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#include <net/transp_v6.h> |
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#include <net/rawv6.h> |
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#include <net/ndisc.h> |
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#include <net/addrconf.h> |
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#include <net/ipv6_frag.h> |
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#include <net/inet_ecn.h> |
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|
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static const char ip6_frag_cache_name[] = "ip6-frags"; |
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|
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static u8 ip6_frag_ecn(const struct ipv6hdr *ipv6h) |
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{ |
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return 1 << (ipv6_get_dsfield(ipv6h) & INET_ECN_MASK); |
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} |
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static struct inet_frags ip6_frags; |
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|
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static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *skb, |
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struct sk_buff *prev_tail, struct net_device *dev); |
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|
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static void ip6_frag_expire(struct timer_list *t) |
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{ |
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struct inet_frag_queue *frag = from_timer(frag, t, timer); |
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struct frag_queue *fq; |
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fq = container_of(frag, struct frag_queue, q); |
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ip6frag_expire_frag_queue(fq->q.fqdir->net, fq); |
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} |
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static struct frag_queue * |
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fq_find(struct net *net, __be32 id, const struct ipv6hdr *hdr, int iif) |
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{ |
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struct frag_v6_compare_key key = { |
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.id = id, |
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.saddr = hdr->saddr, |
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.daddr = hdr->daddr, |
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.user = IP6_DEFRAG_LOCAL_DELIVER, |
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.iif = iif, |
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}; |
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struct inet_frag_queue *q; |
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if (!(ipv6_addr_type(&hdr->daddr) & (IPV6_ADDR_MULTICAST | |
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IPV6_ADDR_LINKLOCAL))) |
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key.iif = 0; |
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q = inet_frag_find(net->ipv6.fqdir, &key); |
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if (!q) |
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return NULL; |
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return container_of(q, struct frag_queue, q); |
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} |
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static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb, |
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struct frag_hdr *fhdr, int nhoff, |
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u32 *prob_offset) |
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{ |
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struct net *net = dev_net(skb_dst(skb)->dev); |
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int offset, end, fragsize; |
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struct sk_buff *prev_tail; |
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struct net_device *dev; |
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int err = -ENOENT; |
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u8 ecn; |
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if (fq->q.flags & INET_FRAG_COMPLETE) |
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goto err; |
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err = -EINVAL; |
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offset = ntohs(fhdr->frag_off) & ~0x7; |
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end = offset + (ntohs(ipv6_hdr(skb)->payload_len) - |
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((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1))); |
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if ((unsigned int)end > IPV6_MAXPLEN) { |
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*prob_offset = (u8 *)&fhdr->frag_off - skb_network_header(skb); |
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/* note that if prob_offset is set, the skb is freed elsewhere, |
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* we do not free it here. |
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*/ |
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return -1; |
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} |
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ecn = ip6_frag_ecn(ipv6_hdr(skb)); |
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if (skb->ip_summed == CHECKSUM_COMPLETE) { |
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const unsigned char *nh = skb_network_header(skb); |
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skb->csum = csum_sub(skb->csum, |
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csum_partial(nh, (u8 *)(fhdr + 1) - nh, |
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0)); |
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} |
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|
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/* Is this the final fragment? */ |
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if (!(fhdr->frag_off & htons(IP6_MF))) { |
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/* If we already have some bits beyond end |
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* or have different end, the segment is corrupted. |
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*/ |
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if (end < fq->q.len || |
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((fq->q.flags & INET_FRAG_LAST_IN) && end != fq->q.len)) |
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goto discard_fq; |
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fq->q.flags |= INET_FRAG_LAST_IN; |
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fq->q.len = end; |
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} else { |
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/* Check if the fragment is rounded to 8 bytes. |
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* Required by the RFC. |
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*/ |
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if (end & 0x7) { |
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/* RFC2460 says always send parameter problem in |
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* this case. -DaveM |
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*/ |
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*prob_offset = offsetof(struct ipv6hdr, payload_len); |
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return -1; |
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} |
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if (end > fq->q.len) { |
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/* Some bits beyond end -> corruption. */ |
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if (fq->q.flags & INET_FRAG_LAST_IN) |
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goto discard_fq; |
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fq->q.len = end; |
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} |
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} |
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if (end == offset) |
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goto discard_fq; |
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err = -ENOMEM; |
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/* Point into the IP datagram 'data' part. */ |
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if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data)) |
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goto discard_fq; |
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err = pskb_trim_rcsum(skb, end - offset); |
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if (err) |
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goto discard_fq; |
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/* Note : skb->rbnode and skb->dev share the same location. */ |
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dev = skb->dev; |
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/* Makes sure compiler wont do silly aliasing games */ |
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barrier(); |
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prev_tail = fq->q.fragments_tail; |
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err = inet_frag_queue_insert(&fq->q, skb, offset, end); |
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if (err) |
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goto insert_error; |
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if (dev) |
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fq->iif = dev->ifindex; |
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fq->q.stamp = skb->tstamp; |
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fq->q.meat += skb->len; |
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fq->ecn |= ecn; |
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add_frag_mem_limit(fq->q.fqdir, skb->truesize); |
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fragsize = -skb_network_offset(skb) + skb->len; |
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if (fragsize > fq->q.max_size) |
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fq->q.max_size = fragsize; |
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|
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/* The first fragment. |
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* nhoffset is obtained from the first fragment, of course. |
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*/ |
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if (offset == 0) { |
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fq->nhoffset = nhoff; |
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fq->q.flags |= INET_FRAG_FIRST_IN; |
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} |
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if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && |
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fq->q.meat == fq->q.len) { |
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unsigned long orefdst = skb->_skb_refdst; |
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skb->_skb_refdst = 0UL; |
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err = ip6_frag_reasm(fq, skb, prev_tail, dev); |
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skb->_skb_refdst = orefdst; |
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return err; |
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} |
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skb_dst_drop(skb); |
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return -EINPROGRESS; |
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insert_error: |
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if (err == IPFRAG_DUP) { |
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kfree_skb(skb); |
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return -EINVAL; |
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} |
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err = -EINVAL; |
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__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), |
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IPSTATS_MIB_REASM_OVERLAPS); |
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discard_fq: |
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inet_frag_kill(&fq->q); |
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__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), |
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IPSTATS_MIB_REASMFAILS); |
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err: |
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kfree_skb(skb); |
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return err; |
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} |
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/* |
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* Check if this packet is complete. |
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* |
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* It is called with locked fq, and caller must check that |
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* queue is eligible for reassembly i.e. it is not COMPLETE, |
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* the last and the first frames arrived and all the bits are here. |
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*/ |
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static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *skb, |
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struct sk_buff *prev_tail, struct net_device *dev) |
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{ |
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struct net *net = fq->q.fqdir->net; |
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unsigned int nhoff; |
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void *reasm_data; |
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int payload_len; |
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u8 ecn; |
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inet_frag_kill(&fq->q); |
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ecn = ip_frag_ecn_table[fq->ecn]; |
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if (unlikely(ecn == 0xff)) |
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goto out_fail; |
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reasm_data = inet_frag_reasm_prepare(&fq->q, skb, prev_tail); |
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if (!reasm_data) |
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goto out_oom; |
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payload_len = ((skb->data - skb_network_header(skb)) - |
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sizeof(struct ipv6hdr) + fq->q.len - |
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sizeof(struct frag_hdr)); |
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if (payload_len > IPV6_MAXPLEN) |
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goto out_oversize; |
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/* We have to remove fragment header from datagram and to relocate |
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* header in order to calculate ICV correctly. */ |
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nhoff = fq->nhoffset; |
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skb_network_header(skb)[nhoff] = skb_transport_header(skb)[0]; |
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memmove(skb->head + sizeof(struct frag_hdr), skb->head, |
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(skb->data - skb->head) - sizeof(struct frag_hdr)); |
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if (skb_mac_header_was_set(skb)) |
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skb->mac_header += sizeof(struct frag_hdr); |
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skb->network_header += sizeof(struct frag_hdr); |
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skb_reset_transport_header(skb); |
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inet_frag_reasm_finish(&fq->q, skb, reasm_data, true); |
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skb->dev = dev; |
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ipv6_hdr(skb)->payload_len = htons(payload_len); |
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ipv6_change_dsfield(ipv6_hdr(skb), 0xff, ecn); |
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IP6CB(skb)->nhoff = nhoff; |
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IP6CB(skb)->flags |= IP6SKB_FRAGMENTED; |
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IP6CB(skb)->frag_max_size = fq->q.max_size; |
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/* Yes, and fold redundant checksum back. 8) */ |
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skb_postpush_rcsum(skb, skb_network_header(skb), |
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skb_network_header_len(skb)); |
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rcu_read_lock(); |
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__IP6_INC_STATS(net, __in6_dev_stats_get(dev, skb), IPSTATS_MIB_REASMOKS); |
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rcu_read_unlock(); |
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fq->q.rb_fragments = RB_ROOT; |
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fq->q.fragments_tail = NULL; |
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fq->q.last_run_head = NULL; |
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return 1; |
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out_oversize: |
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net_dbg_ratelimited("ip6_frag_reasm: payload len = %d\n", payload_len); |
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goto out_fail; |
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out_oom: |
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net_dbg_ratelimited("ip6_frag_reasm: no memory for reassembly\n"); |
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out_fail: |
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rcu_read_lock(); |
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__IP6_INC_STATS(net, __in6_dev_stats_get(dev, skb), IPSTATS_MIB_REASMFAILS); |
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rcu_read_unlock(); |
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inet_frag_kill(&fq->q); |
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return -1; |
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} |
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static int ipv6_frag_rcv(struct sk_buff *skb) |
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{ |
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struct frag_hdr *fhdr; |
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struct frag_queue *fq; |
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const struct ipv6hdr *hdr = ipv6_hdr(skb); |
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struct net *net = dev_net(skb_dst(skb)->dev); |
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u8 nexthdr; |
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int iif; |
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if (IP6CB(skb)->flags & IP6SKB_FRAGMENTED) |
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goto fail_hdr; |
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__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMREQDS); |
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/* Jumbo payload inhibits frag. header */ |
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if (hdr->payload_len == 0) |
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goto fail_hdr; |
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if (!pskb_may_pull(skb, (skb_transport_offset(skb) + |
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sizeof(struct frag_hdr)))) |
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goto fail_hdr; |
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hdr = ipv6_hdr(skb); |
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fhdr = (struct frag_hdr *)skb_transport_header(skb); |
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if (!(fhdr->frag_off & htons(IP6_OFFSET | IP6_MF))) { |
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/* It is not a fragmented frame */ |
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skb->transport_header += sizeof(struct frag_hdr); |
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__IP6_INC_STATS(net, |
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ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMOKS); |
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IP6CB(skb)->nhoff = (u8 *)fhdr - skb_network_header(skb); |
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IP6CB(skb)->flags |= IP6SKB_FRAGMENTED; |
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IP6CB(skb)->frag_max_size = ntohs(hdr->payload_len) + |
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sizeof(struct ipv6hdr); |
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return 1; |
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} |
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|
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/* RFC 8200, Section 4.5 Fragment Header: |
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* If the first fragment does not include all headers through an |
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* Upper-Layer header, then that fragment should be discarded and |
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* an ICMP Parameter Problem, Code 3, message should be sent to |
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* the source of the fragment, with the Pointer field set to zero. |
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*/ |
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nexthdr = hdr->nexthdr; |
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if (ipv6frag_thdr_truncated(skb, skb_transport_offset(skb), &nexthdr)) { |
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__IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev), |
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IPSTATS_MIB_INHDRERRORS); |
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icmpv6_param_prob(skb, ICMPV6_HDR_INCOMP, 0); |
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return -1; |
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} |
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iif = skb->dev ? skb->dev->ifindex : 0; |
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fq = fq_find(net, fhdr->identification, hdr, iif); |
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if (fq) { |
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u32 prob_offset = 0; |
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int ret; |
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spin_lock(&fq->q.lock); |
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fq->iif = iif; |
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ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff, |
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&prob_offset); |
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spin_unlock(&fq->q.lock); |
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inet_frag_put(&fq->q); |
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if (prob_offset) { |
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__IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev), |
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IPSTATS_MIB_INHDRERRORS); |
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/* icmpv6_param_prob() calls kfree_skb(skb) */ |
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icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, prob_offset); |
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} |
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return ret; |
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} |
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__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMFAILS); |
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kfree_skb(skb); |
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return -1; |
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fail_hdr: |
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__IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev), |
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IPSTATS_MIB_INHDRERRORS); |
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icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb_network_header_len(skb)); |
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return -1; |
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} |
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static const struct inet6_protocol frag_protocol = { |
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.handler = ipv6_frag_rcv, |
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.flags = INET6_PROTO_NOPOLICY, |
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}; |
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#ifdef CONFIG_SYSCTL |
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static struct ctl_table ip6_frags_ns_ctl_table[] = { |
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{ |
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.procname = "ip6frag_high_thresh", |
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.maxlen = sizeof(unsigned long), |
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.mode = 0644, |
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.proc_handler = proc_doulongvec_minmax, |
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}, |
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{ |
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.procname = "ip6frag_low_thresh", |
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.maxlen = sizeof(unsigned long), |
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.mode = 0644, |
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.proc_handler = proc_doulongvec_minmax, |
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}, |
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{ |
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.procname = "ip6frag_time", |
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.maxlen = sizeof(int), |
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.mode = 0644, |
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.proc_handler = proc_dointvec_jiffies, |
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}, |
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{ } |
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}; |
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/* secret interval has been deprecated */ |
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static int ip6_frags_secret_interval_unused; |
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static struct ctl_table ip6_frags_ctl_table[] = { |
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{ |
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.procname = "ip6frag_secret_interval", |
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.data = &ip6_frags_secret_interval_unused, |
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.maxlen = sizeof(int), |
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.mode = 0644, |
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.proc_handler = proc_dointvec_jiffies, |
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}, |
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{ } |
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}; |
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static int __net_init ip6_frags_ns_sysctl_register(struct net *net) |
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{ |
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struct ctl_table *table; |
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struct ctl_table_header *hdr; |
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table = ip6_frags_ns_ctl_table; |
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if (!net_eq(net, &init_net)) { |
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table = kmemdup(table, sizeof(ip6_frags_ns_ctl_table), GFP_KERNEL); |
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if (!table) |
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goto err_alloc; |
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} |
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table[0].data = &net->ipv6.fqdir->high_thresh; |
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table[0].extra1 = &net->ipv6.fqdir->low_thresh; |
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table[1].data = &net->ipv6.fqdir->low_thresh; |
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table[1].extra2 = &net->ipv6.fqdir->high_thresh; |
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table[2].data = &net->ipv6.fqdir->timeout; |
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hdr = register_net_sysctl(net, "net/ipv6", table); |
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if (!hdr) |
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goto err_reg; |
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net->ipv6.sysctl.frags_hdr = hdr; |
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return 0; |
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err_reg: |
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if (!net_eq(net, &init_net)) |
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kfree(table); |
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err_alloc: |
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return -ENOMEM; |
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} |
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static void __net_exit ip6_frags_ns_sysctl_unregister(struct net *net) |
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{ |
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struct ctl_table *table; |
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table = net->ipv6.sysctl.frags_hdr->ctl_table_arg; |
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unregister_net_sysctl_table(net->ipv6.sysctl.frags_hdr); |
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if (!net_eq(net, &init_net)) |
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kfree(table); |
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} |
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static struct ctl_table_header *ip6_ctl_header; |
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static int ip6_frags_sysctl_register(void) |
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{ |
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ip6_ctl_header = register_net_sysctl(&init_net, "net/ipv6", |
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ip6_frags_ctl_table); |
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return ip6_ctl_header == NULL ? -ENOMEM : 0; |
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} |
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static void ip6_frags_sysctl_unregister(void) |
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{ |
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unregister_net_sysctl_table(ip6_ctl_header); |
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} |
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#else |
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static int ip6_frags_ns_sysctl_register(struct net *net) |
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{ |
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return 0; |
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} |
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static void ip6_frags_ns_sysctl_unregister(struct net *net) |
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{ |
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} |
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|
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static int ip6_frags_sysctl_register(void) |
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{ |
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return 0; |
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} |
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|
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static void ip6_frags_sysctl_unregister(void) |
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{ |
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} |
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#endif |
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|
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static int __net_init ipv6_frags_init_net(struct net *net) |
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{ |
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int res; |
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|
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res = fqdir_init(&net->ipv6.fqdir, &ip6_frags, net); |
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if (res < 0) |
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return res; |
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net->ipv6.fqdir->high_thresh = IPV6_FRAG_HIGH_THRESH; |
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net->ipv6.fqdir->low_thresh = IPV6_FRAG_LOW_THRESH; |
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net->ipv6.fqdir->timeout = IPV6_FRAG_TIMEOUT; |
|
|
|
res = ip6_frags_ns_sysctl_register(net); |
|
if (res < 0) |
|
fqdir_exit(net->ipv6.fqdir); |
|
return res; |
|
} |
|
|
|
static void __net_exit ipv6_frags_pre_exit_net(struct net *net) |
|
{ |
|
fqdir_pre_exit(net->ipv6.fqdir); |
|
} |
|
|
|
static void __net_exit ipv6_frags_exit_net(struct net *net) |
|
{ |
|
ip6_frags_ns_sysctl_unregister(net); |
|
fqdir_exit(net->ipv6.fqdir); |
|
} |
|
|
|
static struct pernet_operations ip6_frags_ops = { |
|
.init = ipv6_frags_init_net, |
|
.pre_exit = ipv6_frags_pre_exit_net, |
|
.exit = ipv6_frags_exit_net, |
|
}; |
|
|
|
static const struct rhashtable_params ip6_rhash_params = { |
|
.head_offset = offsetof(struct inet_frag_queue, node), |
|
.hashfn = ip6frag_key_hashfn, |
|
.obj_hashfn = ip6frag_obj_hashfn, |
|
.obj_cmpfn = ip6frag_obj_cmpfn, |
|
.automatic_shrinking = true, |
|
}; |
|
|
|
int __init ipv6_frag_init(void) |
|
{ |
|
int ret; |
|
|
|
ip6_frags.constructor = ip6frag_init; |
|
ip6_frags.destructor = NULL; |
|
ip6_frags.qsize = sizeof(struct frag_queue); |
|
ip6_frags.frag_expire = ip6_frag_expire; |
|
ip6_frags.frags_cache_name = ip6_frag_cache_name; |
|
ip6_frags.rhash_params = ip6_rhash_params; |
|
ret = inet_frags_init(&ip6_frags); |
|
if (ret) |
|
goto out; |
|
|
|
ret = inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT); |
|
if (ret) |
|
goto err_protocol; |
|
|
|
ret = ip6_frags_sysctl_register(); |
|
if (ret) |
|
goto err_sysctl; |
|
|
|
ret = register_pernet_subsys(&ip6_frags_ops); |
|
if (ret) |
|
goto err_pernet; |
|
|
|
out: |
|
return ret; |
|
|
|
err_pernet: |
|
ip6_frags_sysctl_unregister(); |
|
err_sysctl: |
|
inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT); |
|
err_protocol: |
|
inet_frags_fini(&ip6_frags); |
|
goto out; |
|
} |
|
|
|
void ipv6_frag_exit(void) |
|
{ |
|
ip6_frags_sysctl_unregister(); |
|
unregister_pernet_subsys(&ip6_frags_ops); |
|
inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT); |
|
inet_frags_fini(&ip6_frags); |
|
}
|
|
|