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[/] [or1k_soc_on_altera_embedded_dev_kit/] [trunk/] [linux-2.6/] [linux-2.6.24/] [net/] [ipv6/] [netfilter/] [nf_conntrack_reasm.c] - Rev 17
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/* * IPv6 fragment reassembly for connection tracking * * Copyright (C)2004 USAGI/WIDE Project * * Author: * Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp> * * Based on: net/ipv6/reassembly.c * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <linux/errno.h> #include <linux/types.h> #include <linux/string.h> #include <linux/socket.h> #include <linux/sockios.h> #include <linux/jiffies.h> #include <linux/net.h> #include <linux/list.h> #include <linux/netdevice.h> #include <linux/in6.h> #include <linux/ipv6.h> #include <linux/icmpv6.h> #include <linux/random.h> #include <linux/jhash.h> #include <net/sock.h> #include <net/snmp.h> #include <net/inet_frag.h> #include <net/ipv6.h> #include <net/protocol.h> #include <net/transp_v6.h> #include <net/rawv6.h> #include <net/ndisc.h> #include <net/addrconf.h> #include <linux/sysctl.h> #include <linux/netfilter.h> #include <linux/netfilter_ipv6.h> #include <linux/kernel.h> #include <linux/module.h> #define NF_CT_FRAG6_HIGH_THRESH 262144 /* == 256*1024 */ #define NF_CT_FRAG6_LOW_THRESH 196608 /* == 192*1024 */ #define NF_CT_FRAG6_TIMEOUT IPV6_FRAG_TIMEOUT struct nf_ct_frag6_skb_cb { struct inet6_skb_parm h; int offset; struct sk_buff *orig; }; #define NFCT_FRAG6_CB(skb) ((struct nf_ct_frag6_skb_cb*)((skb)->cb)) struct nf_ct_frag6_queue { struct inet_frag_queue q; __be32 id; /* fragment id */ struct in6_addr saddr; struct in6_addr daddr; unsigned int csum; __u16 nhoffset; }; struct inet_frags_ctl nf_frags_ctl __read_mostly = { .high_thresh = 256 * 1024, .low_thresh = 192 * 1024, .timeout = IPV6_FRAG_TIMEOUT, .secret_interval = 10 * 60 * HZ, }; static struct inet_frags nf_frags; static unsigned int ip6qhashfn(__be32 id, struct in6_addr *saddr, struct in6_addr *daddr) { u32 a, b, c; a = (__force u32)saddr->s6_addr32[0]; b = (__force u32)saddr->s6_addr32[1]; c = (__force u32)saddr->s6_addr32[2]; a += JHASH_GOLDEN_RATIO; b += JHASH_GOLDEN_RATIO; c += nf_frags.rnd; __jhash_mix(a, b, c); a += (__force u32)saddr->s6_addr32[3]; b += (__force u32)daddr->s6_addr32[0]; c += (__force u32)daddr->s6_addr32[1]; __jhash_mix(a, b, c); a += (__force u32)daddr->s6_addr32[2]; b += (__force u32)daddr->s6_addr32[3]; c += (__force u32)id; __jhash_mix(a, b, c); return c & (INETFRAGS_HASHSZ - 1); } static unsigned int nf_hashfn(struct inet_frag_queue *q) { struct nf_ct_frag6_queue *nq; nq = container_of(q, struct nf_ct_frag6_queue, q); return ip6qhashfn(nq->id, &nq->saddr, &nq->daddr); } static void nf_skb_free(struct sk_buff *skb) { if (NFCT_FRAG6_CB(skb)->orig) kfree_skb(NFCT_FRAG6_CB(skb)->orig); } /* Memory Tracking Functions. */ static inline void frag_kfree_skb(struct sk_buff *skb, unsigned int *work) { if (work) *work -= skb->truesize; atomic_sub(skb->truesize, &nf_frags.mem); nf_skb_free(skb); kfree_skb(skb); } /* Destruction primitives. */ static __inline__ void fq_put(struct nf_ct_frag6_queue *fq) { inet_frag_put(&fq->q, &nf_frags); } /* Kill fq entry. It is not destroyed immediately, * because caller (and someone more) holds reference count. */ static __inline__ void fq_kill(struct nf_ct_frag6_queue *fq) { inet_frag_kill(&fq->q, &nf_frags); } static void nf_ct_frag6_evictor(void) { inet_frag_evictor(&nf_frags); } static void nf_ct_frag6_expire(unsigned long data) { struct nf_ct_frag6_queue *fq; fq = container_of((struct inet_frag_queue *)data, struct nf_ct_frag6_queue, q); spin_lock(&fq->q.lock); if (fq->q.last_in & COMPLETE) goto out; fq_kill(fq); out: spin_unlock(&fq->q.lock); fq_put(fq); } /* Creation primitives. */ static __inline__ struct nf_ct_frag6_queue * fq_find(__be32 id, struct in6_addr *src, struct in6_addr *dst) { struct inet_frag_queue *q; struct ip6_create_arg arg; unsigned int hash; arg.id = id; arg.src = src; arg.dst = dst; hash = ip6qhashfn(id, src, dst); q = inet_frag_find(&nf_frags, &arg, hash); if (q == NULL) goto oom; return container_of(q, struct nf_ct_frag6_queue, q); oom: pr_debug("Can't alloc new queue\n"); return NULL; } static int nf_ct_frag6_queue(struct nf_ct_frag6_queue *fq, struct sk_buff *skb, struct frag_hdr *fhdr, int nhoff) { struct sk_buff *prev, *next; int offset, end; if (fq->q.last_in & COMPLETE) { pr_debug("Allready completed\n"); goto err; } offset = ntohs(fhdr->frag_off) & ~0x7; end = offset + (ntohs(ipv6_hdr(skb)->payload_len) - ((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1))); if ((unsigned int)end > IPV6_MAXPLEN) { pr_debug("offset is too large.\n"); return -1; } if (skb->ip_summed == CHECKSUM_COMPLETE) { const unsigned char *nh = skb_network_header(skb); skb->csum = csum_sub(skb->csum, csum_partial(nh, (u8 *)(fhdr + 1) - nh, 0)); } /* Is this the final fragment? */ if (!(fhdr->frag_off & htons(IP6_MF))) { /* If we already have some bits beyond end * or have different end, the segment is corrupted. */ if (end < fq->q.len || ((fq->q.last_in & LAST_IN) && end != fq->q.len)) { pr_debug("already received last fragment\n"); goto err; } fq->q.last_in |= LAST_IN; fq->q.len = end; } else { /* Check if the fragment is rounded to 8 bytes. * Required by the RFC. */ if (end & 0x7) { /* RFC2460 says always send parameter problem in * this case. -DaveM */ pr_debug("end of fragment not rounded to 8 bytes.\n"); return -1; } if (end > fq->q.len) { /* Some bits beyond end -> corruption. */ if (fq->q.last_in & LAST_IN) { pr_debug("last packet already reached.\n"); goto err; } fq->q.len = end; } } if (end == offset) goto err; /* Point into the IP datagram 'data' part. */ if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data)) { pr_debug("queue: message is too short.\n"); goto err; } if (pskb_trim_rcsum(skb, end - offset)) { pr_debug("Can't trim\n"); goto err; } /* Find out which fragments are in front and at the back of us * in the chain of fragments so far. We must know where to put * this fragment, right? */ prev = NULL; for (next = fq->q.fragments; next != NULL; next = next->next) { if (NFCT_FRAG6_CB(next)->offset >= offset) break; /* bingo! */ prev = next; } /* We found where to put this one. Check for overlap with * preceding fragment, and, if needed, align things so that * any overlaps are eliminated. */ if (prev) { int i = (NFCT_FRAG6_CB(prev)->offset + prev->len) - offset; if (i > 0) { offset += i; if (end <= offset) { pr_debug("overlap\n"); goto err; } if (!pskb_pull(skb, i)) { pr_debug("Can't pull\n"); goto err; } if (skb->ip_summed != CHECKSUM_UNNECESSARY) skb->ip_summed = CHECKSUM_NONE; } } /* Look for overlap with succeeding segments. * If we can merge fragments, do it. */ while (next && NFCT_FRAG6_CB(next)->offset < end) { /* overlap is 'i' bytes */ int i = end - NFCT_FRAG6_CB(next)->offset; if (i < next->len) { /* Eat head of the next overlapped fragment * and leave the loop. The next ones cannot overlap. */ pr_debug("Eat head of the overlapped parts.: %d", i); if (!pskb_pull(next, i)) goto err; /* next fragment */ NFCT_FRAG6_CB(next)->offset += i; fq->q.meat -= i; if (next->ip_summed != CHECKSUM_UNNECESSARY) next->ip_summed = CHECKSUM_NONE; break; } else { struct sk_buff *free_it = next; /* Old fragmnet is completely overridden with * new one drop it. */ next = next->next; if (prev) prev->next = next; else fq->q.fragments = next; fq->q.meat -= free_it->len; frag_kfree_skb(free_it, NULL); } } NFCT_FRAG6_CB(skb)->offset = offset; /* Insert this fragment in the chain of fragments. */ skb->next = next; if (prev) prev->next = skb; else fq->q.fragments = skb; skb->dev = NULL; fq->q.stamp = skb->tstamp; fq->q.meat += skb->len; atomic_add(skb->truesize, &nf_frags.mem); /* The first fragment. * nhoffset is obtained from the first fragment, of course. */ if (offset == 0) { fq->nhoffset = nhoff; fq->q.last_in |= FIRST_IN; } write_lock(&nf_frags.lock); list_move_tail(&fq->q.lru_list, &nf_frags.lru_list); write_unlock(&nf_frags.lock); return 0; err: return -1; } /* * Check if this packet is complete. * Returns NULL on failure by any reason, and pointer * to current nexthdr field in reassembled frame. * * It is called with locked fq, and caller must check that * queue is eligible for reassembly i.e. it is not COMPLETE, * the last and the first frames arrived and all the bits are here. */ static struct sk_buff * nf_ct_frag6_reasm(struct nf_ct_frag6_queue *fq, struct net_device *dev) { struct sk_buff *fp, *op, *head = fq->q.fragments; int payload_len; fq_kill(fq); BUG_TRAP(head != NULL); BUG_TRAP(NFCT_FRAG6_CB(head)->offset == 0); /* Unfragmented part is taken from the first segment. */ payload_len = ((head->data - skb_network_header(head)) - sizeof(struct ipv6hdr) + fq->q.len - sizeof(struct frag_hdr)); if (payload_len > IPV6_MAXPLEN) { pr_debug("payload len is too large.\n"); goto out_oversize; } /* Head of list must not be cloned. */ if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) { pr_debug("skb is cloned but can't expand head"); goto out_oom; } /* If the first fragment is fragmented itself, we split * it to two chunks: the first with data and paged part * and the second, holding only fragments. */ if (skb_shinfo(head)->frag_list) { struct sk_buff *clone; int i, plen = 0; if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) { pr_debug("Can't alloc skb\n"); goto out_oom; } clone->next = head->next; head->next = clone; skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; skb_shinfo(head)->frag_list = NULL; for (i=0; i<skb_shinfo(head)->nr_frags; i++) plen += skb_shinfo(head)->frags[i].size; clone->len = clone->data_len = head->data_len - plen; head->data_len -= clone->len; head->len -= clone->len; clone->csum = 0; clone->ip_summed = head->ip_summed; NFCT_FRAG6_CB(clone)->orig = NULL; atomic_add(clone->truesize, &nf_frags.mem); } /* We have to remove fragment header from datagram and to relocate * header in order to calculate ICV correctly. */ skb_network_header(head)[fq->nhoffset] = skb_transport_header(head)[0]; memmove(head->head + sizeof(struct frag_hdr), head->head, (head->data - head->head) - sizeof(struct frag_hdr)); head->mac_header += sizeof(struct frag_hdr); head->network_header += sizeof(struct frag_hdr); skb_shinfo(head)->frag_list = head->next; skb_reset_transport_header(head); skb_push(head, head->data - skb_network_header(head)); atomic_sub(head->truesize, &nf_frags.mem); for (fp=head->next; fp; fp = fp->next) { head->data_len += fp->len; head->len += fp->len; if (head->ip_summed != fp->ip_summed) head->ip_summed = CHECKSUM_NONE; else if (head->ip_summed == CHECKSUM_COMPLETE) head->csum = csum_add(head->csum, fp->csum); head->truesize += fp->truesize; atomic_sub(fp->truesize, &nf_frags.mem); } head->next = NULL; head->dev = dev; head->tstamp = fq->q.stamp; ipv6_hdr(head)->payload_len = htons(payload_len); /* Yes, and fold redundant checksum back. 8) */ if (head->ip_summed == CHECKSUM_COMPLETE) head->csum = csum_partial(skb_network_header(head), skb_network_header_len(head), head->csum); fq->q.fragments = NULL; /* all original skbs are linked into the NFCT_FRAG6_CB(head).orig */ fp = skb_shinfo(head)->frag_list; if (NFCT_FRAG6_CB(fp)->orig == NULL) /* at above code, head skb is divided into two skbs. */ fp = fp->next; op = NFCT_FRAG6_CB(head)->orig; for (; fp; fp = fp->next) { struct sk_buff *orig = NFCT_FRAG6_CB(fp)->orig; op->next = orig; op = orig; NFCT_FRAG6_CB(fp)->orig = NULL; } return head; out_oversize: if (net_ratelimit()) printk(KERN_DEBUG "nf_ct_frag6_reasm: payload len = %d\n", payload_len); goto out_fail; out_oom: if (net_ratelimit()) printk(KERN_DEBUG "nf_ct_frag6_reasm: no memory for reassembly\n"); out_fail: return NULL; } /* * find the header just before Fragment Header. * * if success return 0 and set ... * (*prevhdrp): the value of "Next Header Field" in the header * just before Fragment Header. * (*prevhoff): the offset of "Next Header Field" in the header * just before Fragment Header. * (*fhoff) : the offset of Fragment Header. * * Based on ipv6_skip_hdr() in net/ipv6/exthdr.c * */ static int find_prev_fhdr(struct sk_buff *skb, u8 *prevhdrp, int *prevhoff, int *fhoff) { u8 nexthdr = ipv6_hdr(skb)->nexthdr; const int netoff = skb_network_offset(skb); u8 prev_nhoff = netoff + offsetof(struct ipv6hdr, nexthdr); int start = netoff + sizeof(struct ipv6hdr); int len = skb->len - start; u8 prevhdr = NEXTHDR_IPV6; while (nexthdr != NEXTHDR_FRAGMENT) { struct ipv6_opt_hdr hdr; int hdrlen; if (!ipv6_ext_hdr(nexthdr)) { return -1; } if (len < (int)sizeof(struct ipv6_opt_hdr)) { pr_debug("too short\n"); return -1; } if (nexthdr == NEXTHDR_NONE) { pr_debug("next header is none\n"); return -1; } if (skb_copy_bits(skb, start, &hdr, sizeof(hdr))) BUG(); if (nexthdr == NEXTHDR_AUTH) hdrlen = (hdr.hdrlen+2)<<2; else hdrlen = ipv6_optlen(&hdr); prevhdr = nexthdr; prev_nhoff = start; nexthdr = hdr.nexthdr; len -= hdrlen; start += hdrlen; } if (len < 0) return -1; *prevhdrp = prevhdr; *prevhoff = prev_nhoff; *fhoff = start; return 0; } struct sk_buff *nf_ct_frag6_gather(struct sk_buff *skb) { struct sk_buff *clone; struct net_device *dev = skb->dev; struct frag_hdr *fhdr; struct nf_ct_frag6_queue *fq; struct ipv6hdr *hdr; int fhoff, nhoff; u8 prevhdr; struct sk_buff *ret_skb = NULL; /* Jumbo payload inhibits frag. header */ if (ipv6_hdr(skb)->payload_len == 0) { pr_debug("payload len = 0\n"); return skb; } if (find_prev_fhdr(skb, &prevhdr, &nhoff, &fhoff) < 0) return skb; clone = skb_clone(skb, GFP_ATOMIC); if (clone == NULL) { pr_debug("Can't clone skb\n"); return skb; } NFCT_FRAG6_CB(clone)->orig = skb; if (!pskb_may_pull(clone, fhoff + sizeof(*fhdr))) { pr_debug("message is too short.\n"); goto ret_orig; } skb_set_transport_header(clone, fhoff); hdr = ipv6_hdr(clone); fhdr = (struct frag_hdr *)skb_transport_header(clone); if (!(fhdr->frag_off & htons(0xFFF9))) { pr_debug("Invalid fragment offset\n"); /* It is not a fragmented frame */ goto ret_orig; } if (atomic_read(&nf_frags.mem) > nf_frags_ctl.high_thresh) nf_ct_frag6_evictor(); fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr); if (fq == NULL) { pr_debug("Can't find and can't create new queue\n"); goto ret_orig; } spin_lock(&fq->q.lock); if (nf_ct_frag6_queue(fq, clone, fhdr, nhoff) < 0) { spin_unlock(&fq->q.lock); pr_debug("Can't insert skb to queue\n"); fq_put(fq); goto ret_orig; } if (fq->q.last_in == (FIRST_IN|LAST_IN) && fq->q.meat == fq->q.len) { ret_skb = nf_ct_frag6_reasm(fq, dev); if (ret_skb == NULL) pr_debug("Can't reassemble fragmented packets\n"); } spin_unlock(&fq->q.lock); fq_put(fq); return ret_skb; ret_orig: kfree_skb(clone); return skb; } void nf_ct_frag6_output(unsigned int hooknum, struct sk_buff *skb, struct net_device *in, struct net_device *out, int (*okfn)(struct sk_buff *)) { struct sk_buff *s, *s2; for (s = NFCT_FRAG6_CB(skb)->orig; s;) { nf_conntrack_put_reasm(s->nfct_reasm); nf_conntrack_get_reasm(skb); s->nfct_reasm = skb; s2 = s->next; s->next = NULL; NF_HOOK_THRESH(PF_INET6, hooknum, s, in, out, okfn, NF_IP6_PRI_CONNTRACK_DEFRAG + 1); s = s2; } nf_conntrack_put_reasm(skb); } int nf_ct_frag6_kfree_frags(struct sk_buff *skb) { struct sk_buff *s, *s2; for (s = NFCT_FRAG6_CB(skb)->orig; s; s = s2) { s2 = s->next; kfree_skb(s); } kfree_skb(skb); return 0; } int nf_ct_frag6_init(void) { nf_frags.ctl = &nf_frags_ctl; nf_frags.hashfn = nf_hashfn; nf_frags.constructor = ip6_frag_init; nf_frags.destructor = NULL; nf_frags.skb_free = nf_skb_free; nf_frags.qsize = sizeof(struct nf_ct_frag6_queue); nf_frags.match = ip6_frag_match; nf_frags.frag_expire = nf_ct_frag6_expire; inet_frags_init(&nf_frags); return 0; } void nf_ct_frag6_cleanup(void) { inet_frags_fini(&nf_frags); nf_frags_ctl.low_thresh = 0; nf_ct_frag6_evictor(); }
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