static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, struct net_device *dev) { struct net *net = container_of(qp->q.net, struct net, ipv4.frags); struct iphdr *iph; struct sk_buff *fp, *head = qp->q.fragments; int len; int ihlen; int err; int sum_truesize; u8 ecn; ipq_kill(qp); ecn = ip_frag_ecn_table[qp->ecn]; if (unlikely(ecn == 0xff)) { err = -EINVAL; goto out_fail; } /* Make the one we just received the head. */ if (prev) { head = prev->next; fp = skb_clone(head, GFP_ATOMIC); if (!fp) goto out_nomem; fp->next = head->next; if (!fp->next) qp->q.fragments_tail = fp; prev->next = fp; skb_morph(head, qp->q.fragments); head->next = qp->q.fragments->next; consume_skb(qp->q.fragments); qp->q.fragments = head; } WARN_ON(head == NULL); WARN_ON(FRAG_CB(head)->offset != 0); /* Allocate a new buffer for the datagram. */ ihlen = ip_hdrlen(head); len = ihlen + qp->q.len; err = -E2BIG; if (len > 65535) goto out_oversize; /* Head of list must not be cloned. */ if (skb_unclone(head, GFP_ATOMIC)) goto out_nomem; /* 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_has_frag_list(head)) { struct sk_buff *clone; int i, plen = 0; if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) goto out_nomem; clone->next = head->next; head->next = clone; skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; skb_frag_list_init(head); for (i = 0; i < skb_shinfo(head)->nr_frags; i++) plen += skb_frag_size(&skb_shinfo(head)->frags[i]); 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; add_frag_mem_limit(&qp->q, clone->truesize); } skb_push(head, head->data - skb_network_header(head)); sum_truesize = head->truesize; for (fp = head->next; fp;) { bool headstolen; int delta; struct sk_buff *next = fp->next; sum_truesize += fp->truesize; 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); if (skb_try_coalesce(head, fp, &headstolen, &delta)) { kfree_skb_partial(fp, headstolen); } else { if (!skb_shinfo(head)->frag_list) skb_shinfo(head)->frag_list = fp; head->data_len += fp->len; head->len += fp->len; head->truesize += fp->truesize; } fp = next; } sub_frag_mem_limit(&qp->q, sum_truesize); head->next = NULL; head->dev = dev; head->tstamp = qp->q.stamp; IPCB(head)->frag_max_size = qp->q.max_size; iph = ip_hdr(head); /* max_size != 0 implies at least one fragment had IP_DF set */ iph->frag_off = qp->q.max_size ? htons(IP_DF) : 0; iph->tot_len = htons(len); iph->tos |= ecn; ip_send_check(iph); IP_INC_STATS_BH(net, IPSTATS_MIB_REASMOKS); qp->q.fragments = NULL; qp->q.fragments_tail = NULL; return 0; out_nomem: LIMIT_NETDEBUG(KERN_ERR pr_fmt("queue_glue: no memory for gluing queue %p\n"), qp); err = -ENOMEM; goto out_fail; out_oversize: net_info_ratelimited("Oversized IP packet from %pI4\n", &qp->saddr); out_fail: IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); return err; }
static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, struct net_device *dev) { struct net *net = container_of(qp->q.net, struct net, ipv4.frags); struct iphdr *iph; struct sk_buff *fp, *head = qp->q.fragments; int len; int ihlen; int err; u8 ecn; ipq_kill(qp); ecn = ip_frag_ecn_table[qp->ecn]; if (unlikely(ecn == 0xff)) { err = -EINVAL; goto out_fail; } /* Make the one we just received the head. */ if (prev) { head = prev->next; fp = skb_clone(head, GFP_ATOMIC); if (!fp) goto out_nomem; fp->next = head->next; if (!fp->next) qp->q.fragments_tail = fp; prev->next = fp; skb_morph(head, qp->q.fragments); head->next = qp->q.fragments->next; consume_skb(qp->q.fragments); qp->q.fragments = head; } WARN_ON(!head); WARN_ON(FRAG_CB(head)->offset != 0); /* Allocate a new buffer for the datagram. */ ihlen = ip_hdrlen(head); len = ihlen + qp->q.len; err = -E2BIG; if (len > 65535) goto out_oversize; /* Head of list must not be cloned. */ if (skb_unclone(head, GFP_ATOMIC)) goto out_nomem; /* 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_has_frag_list(head)) { struct sk_buff *clone; int i, plen = 0; clone = alloc_skb(0, GFP_ATOMIC); if (!clone) goto out_nomem; clone->next = head->next; head->next = clone; skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; skb_frag_list_init(head); for (i = 0; i < skb_shinfo(head)->nr_frags; i++) plen += skb_frag_size(&skb_shinfo(head)->frags[i]); 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; add_frag_mem_limit(qp->q.net, clone->truesize); } skb_shinfo(head)->frag_list = head->next; skb_push(head, head->data - skb_network_header(head)); 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; } sub_frag_mem_limit(qp->q.net, head->truesize); head->next = NULL; head->dev = dev; head->tstamp = qp->q.stamp; IPCB(head)->frag_max_size = max(qp->max_df_size, qp->q.max_size); iph = ip_hdr(head); iph->tot_len = htons(len); iph->tos |= ecn; /* When we set IP_DF on a refragmented skb we must also force a * call to ip_fragment to avoid forwarding a DF-skb of size s while * original sender only sent fragments of size f (where f < s). * * We only set DF/IPSKB_FRAG_PMTU if such DF fragment was the largest * frag seen to avoid sending tiny DF-fragments in case skb was built * from one very small df-fragment and one large non-df frag. */ if (qp->max_df_size == qp->q.max_size) { IPCB(head)->flags |= IPSKB_FRAG_PMTU; iph->frag_off = htons(IP_DF); } else { iph->frag_off = 0; } ip_send_check(iph); IP_INC_STATS_BH(net, IPSTATS_MIB_REASMOKS); qp->q.fragments = NULL; qp->q.fragments_tail = NULL; return 0; out_nomem: net_dbg_ratelimited("queue_glue: no memory for gluing queue %p\n", qp); err = -ENOMEM; goto out_fail; out_oversize: net_info_ratelimited("Oversized IP packet from %pI4\n", &qp->saddr); out_fail: IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); return err; }
/* Add new segment to existing queue. */ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) { struct sk_buff *prev, *next; struct net_device *dev; int flags, offset; int ihl, end; int err = -ENOENT; u8 ecn; if (qp->q.last_in & INET_FRAG_COMPLETE) goto err; if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && unlikely(ip_frag_too_far(qp)) && unlikely(err = ip_frag_reinit(qp))) { ipq_kill(qp); goto err; } ecn = ip4_frag_ecn(ip_hdr(skb)->tos); offset = ntohs(ip_hdr(skb)->frag_off); flags = offset & ~IP_OFFSET; offset &= IP_OFFSET; offset <<= 3; /* offset is in 8-byte chunks */ ihl = ip_hdrlen(skb); /* Determine the position of this fragment. */ end = offset + skb->len - skb_network_offset(skb) - ihl; err = -EINVAL; /* Is this the final fragment? */ if ((flags & IP_MF) == 0) { /* If we already have some bits beyond end * or have different end, the segment is corrupted. */ if (end < qp->q.len || ((qp->q.last_in & INET_FRAG_LAST_IN) && end != qp->q.len)) goto err; qp->q.last_in |= INET_FRAG_LAST_IN; qp->q.len = end; } else { if (end&7) { end &= ~7; if (skb->ip_summed != CHECKSUM_UNNECESSARY) skb->ip_summed = CHECKSUM_NONE; } if (end > qp->q.len) { /* Some bits beyond end -> corruption. */ if (qp->q.last_in & INET_FRAG_LAST_IN) goto err; qp->q.len = end; } } if (end == offset) goto err; err = -ENOMEM; if (!pskb_pull(skb, skb_network_offset(skb) + ihl)) goto err; err = pskb_trim_rcsum(skb, end - offset); if (err) 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 = qp->q.fragments_tail; if (!prev || FRAG_CB(prev)->offset < offset) { next = NULL; goto found; } prev = NULL; for (next = qp->q.fragments; next != NULL; next = next->next) { if (FRAG_CB(next)->offset >= offset) break; /* bingo! */ prev = next; } found: /* 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 = (FRAG_CB(prev)->offset + prev->len) - offset; if (i > 0) { offset += i; err = -EINVAL; if (end <= offset) goto err; err = -ENOMEM; if (!pskb_pull(skb, i)) goto err; if (skb->ip_summed != CHECKSUM_UNNECESSARY) skb->ip_summed = CHECKSUM_NONE; } } err = -ENOMEM; while (next && FRAG_CB(next)->offset < end) { int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ if (i < next->len) { /* Eat head of the next overlapped fragment * and leave the loop. The next ones cannot overlap. */ if (!pskb_pull(next, i)) goto err; FRAG_CB(next)->offset += i; qp->q.meat -= i; if (next->ip_summed != CHECKSUM_UNNECESSARY) next->ip_summed = CHECKSUM_NONE; break; } else { struct sk_buff *free_it = next; /* Old fragment is completely overridden with * new one drop it. */ next = next->next; if (prev) prev->next = next; else qp->q.fragments = next; qp->q.meat -= free_it->len; sub_frag_mem_limit(&qp->q, free_it->truesize); kfree_skb(free_it); } } FRAG_CB(skb)->offset = offset; /* Insert this fragment in the chain of fragments. */ skb->next = next; if (!next) qp->q.fragments_tail = skb; if (prev) prev->next = skb; else qp->q.fragments = skb; dev = skb->dev; if (dev) { qp->iif = dev->ifindex; skb->dev = NULL; } qp->q.stamp = skb->tstamp; qp->q.meat += skb->len; qp->ecn |= ecn; add_frag_mem_limit(&qp->q, skb->truesize); if (offset == 0) qp->q.last_in |= INET_FRAG_FIRST_IN; if (ip_hdr(skb)->frag_off & htons(IP_DF) && skb->len + ihl > qp->q.max_size) qp->q.max_size = skb->len + ihl; if (qp->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && qp->q.meat == qp->q.len) { unsigned long orefdst = skb->_skb_refdst; skb->_skb_refdst = 0UL; err = ip_frag_reasm(qp, prev, dev); skb->_skb_refdst = orefdst; return err; } skb_dst_drop(skb); inet_frag_lru_move(&qp->q); return -EINPROGRESS; err: kfree_skb(skb); return err; }
static int lowpan_frag_queue(struct lowpan_frag_queue *fq, struct sk_buff *skb, const u8 frag_type) { struct sk_buff *prev, *next; struct net_device *dev; int end, offset; if (fq->q.flags & INET_FRAG_COMPLETE) goto err; offset = lowpan_cb(skb)->d_offset << 3; end = lowpan_cb(skb)->d_size; /* Is this the final fragment? */ if (offset + skb->len == end) { /* If we already have some bits beyond end * or have different end, the segment is corrupted. */ if (end < fq->q.len || ((fq->q.flags & INET_FRAG_LAST_IN) && end != fq->q.len)) goto err; fq->q.flags |= INET_FRAG_LAST_IN; fq->q.len = end; } else { if (end > fq->q.len) { /* Some bits beyond end -> corruption. */ if (fq->q.flags & INET_FRAG_LAST_IN) goto err; fq->q.len = end; } } /* 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 = fq->q.fragments_tail; if (!prev || lowpan_cb(prev)->d_offset < lowpan_cb(skb)->d_offset) { next = NULL; goto found; } prev = NULL; for (next = fq->q.fragments; next != NULL; next = next->next) { if (lowpan_cb(next)->d_offset >= lowpan_cb(skb)->d_offset) break; /* bingo! */ prev = next; } found: /* Insert this fragment in the chain of fragments. */ skb->next = next; if (!next) fq->q.fragments_tail = skb; if (prev) prev->next = skb; else fq->q.fragments = skb; dev = skb->dev; if (dev) skb->dev = NULL; fq->q.stamp = skb->tstamp; if (frag_type == LOWPAN_DISPATCH_FRAG1) { /* Calculate uncomp. 6lowpan header to estimate full size */ fq->q.meat += lowpan_uncompress_size(skb, NULL); fq->q.flags |= INET_FRAG_FIRST_IN; } else { fq->q.meat += skb->len; } add_frag_mem_limit(&fq->q, skb->truesize); if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && fq->q.meat == fq->q.len) { int res; unsigned long orefdst = skb->_skb_refdst; skb->_skb_refdst = 0UL; res = lowpan_frag_reasm(fq, prev, dev); skb->_skb_refdst = orefdst; return res; } return -1; err: kfree_skb(skb); 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 int lowpan_frag_reasm(struct lowpan_frag_queue *fq, struct sk_buff *prev, struct net_device *dev) { struct sk_buff *fp, *head = fq->q.fragments; int sum_truesize; inet_frag_kill(&fq->q, &lowpan_frags); /* Make the one we just received the head. */ if (prev) { head = prev->next; fp = skb_clone(head, GFP_ATOMIC); if (!fp) goto out_oom; fp->next = head->next; if (!fp->next) fq->q.fragments_tail = fp; prev->next = fp; skb_morph(head, fq->q.fragments); head->next = fq->q.fragments->next; consume_skb(fq->q.fragments); fq->q.fragments = head; } /* Head of list must not be cloned. */ if (skb_unclone(head, GFP_ATOMIC)) 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_has_frag_list(head)) { struct sk_buff *clone; int i, plen = 0; clone = alloc_skb(0, GFP_ATOMIC); if (!clone) goto out_oom; clone->next = head->next; head->next = clone; skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; skb_frag_list_init(head); for (i = 0; i < skb_shinfo(head)->nr_frags; i++) plen += skb_frag_size(&skb_shinfo(head)->frags[i]); clone->len = head->data_len - plen; clone->data_len = clone->len; head->data_len -= clone->len; head->len -= clone->len; add_frag_mem_limit(&fq->q, clone->truesize); } WARN_ON(head == NULL); sum_truesize = head->truesize; for (fp = head->next; fp;) { bool headstolen; int delta; struct sk_buff *next = fp->next; sum_truesize += fp->truesize; if (skb_try_coalesce(head, fp, &headstolen, &delta)) { kfree_skb_partial(fp, headstolen); } else { if (!skb_shinfo(head)->frag_list) skb_shinfo(head)->frag_list = fp; head->data_len += fp->len; head->len += fp->len; head->truesize += fp->truesize; } fp = next; } sub_frag_mem_limit(&fq->q, sum_truesize); head->next = NULL; head->dev = dev; head->tstamp = fq->q.stamp; fq->q.fragments = NULL; fq->q.fragments_tail = NULL; return 1; out_oom: net_dbg_ratelimited("lowpan_frag_reasm: no memory for reassembly\n"); return -1; }
static struct frag_queue * fq_find(struct net *net, __be32 id, const struct ipv6hdr *hdr, int iif) { struct frag_v6_compare_key key = { .id = id, .saddr = hdr->saddr, .daddr = hdr->daddr, .user = IP6_DEFRAG_LOCAL_DELIVER, .iif = iif, }; struct inet_frag_queue *q; if (!(ipv6_addr_type(&hdr->daddr) & (IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL))) key.iif = 0; q = inet_frag_find(&net->ipv6.frags, &key); if (!q) return NULL; return container_of(q, struct frag_queue, q); } static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb, struct frag_hdr *fhdr, int nhoff, u32 *prob_offset) { struct net *net = dev_net(skb_dst(skb)->dev); int offset, end, fragsize; struct sk_buff *prev_tail; struct net_device *dev; int err = -ENOENT; u8 ecn; if (fq->q.flags & INET_FRAG_COMPLETE) goto err; err = -EINVAL; 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) { *prob_offset = (u8 *)&fhdr->frag_off - skb_network_header(skb); /* note that if prob_offset is set, the skb is freed elsewhere, * we do not free it here. */ return -1; } ecn = ip6_frag_ecn(ipv6_hdr(skb)); 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.flags & INET_FRAG_LAST_IN) && end != fq->q.len)) goto discard_fq; fq->q.flags |= INET_FRAG_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 */ *prob_offset = offsetof(struct ipv6hdr, payload_len); return -1; } if (end > fq->q.len) { /* Some bits beyond end -> corruption. */ if (fq->q.flags & INET_FRAG_LAST_IN) goto discard_fq; fq->q.len = end; } } if (end == offset) goto discard_fq; err = -ENOMEM; /* Point into the IP datagram 'data' part. */ if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data)) goto discard_fq; err = pskb_trim_rcsum(skb, end - offset); if (err) goto discard_fq; /* Note : skb->rbnode and skb->dev share the same location. */ dev = skb->dev; /* Makes sure compiler wont do silly aliasing games */ barrier(); prev_tail = fq->q.fragments_tail; err = inet_frag_queue_insert(&fq->q, skb, offset, end); if (err) goto insert_error; if (dev) fq->iif = dev->ifindex; fq->q.stamp = skb->tstamp; fq->q.meat += skb->len; fq->ecn |= ecn; add_frag_mem_limit(fq->q.net, skb->truesize); fragsize = -skb_network_offset(skb) + skb->len; if (fragsize > fq->q.max_size) fq->q.max_size = fragsize; /* The first fragment. * nhoffset is obtained from the first fragment, of course. */ if (offset == 0) { fq->nhoffset = nhoff; fq->q.flags |= INET_FRAG_FIRST_IN; } if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && fq->q.meat == fq->q.len) { unsigned long orefdst = skb->_skb_refdst; skb->_skb_refdst = 0UL; err = ip6_frag_reasm(fq, skb, prev_tail, dev); skb->_skb_refdst = orefdst; return err; } skb_dst_drop(skb); return -EINPROGRESS; insert_error: if (err == IPFRAG_DUP) { kfree_skb(skb); return -EINVAL; } err = -EINVAL; __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASM_OVERLAPS); discard_fq: inet_frag_kill(&fq->q); __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMFAILS); err: kfree_skb(skb); return err; }
/* * 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 int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev, struct net_device *dev) { struct net *net = container_of(fq->q.net, struct net, ipv6.frags); struct sk_buff *fp, *head = fq->q.fragments; int payload_len; unsigned int nhoff; int sum_truesize; u8 ecn; inet_frag_kill(&fq->q, &ip6_frags); ecn = ip_frag_ecn_table[fq->ecn]; if (unlikely(ecn == 0xff)) goto out_fail; /* Make the one we just received the head. */ if (prev) { head = prev->next; fp = skb_clone(head, GFP_ATOMIC); if (!fp) goto out_oom; fp->next = head->next; if (!fp->next) fq->q.fragments_tail = fp; prev->next = fp; skb_morph(head, fq->q.fragments); head->next = fq->q.fragments->next; consume_skb(fq->q.fragments); fq->q.fragments = head; } WARN_ON(head == NULL); WARN_ON(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) goto out_oversize; /* Head of list must not be cloned. */ if (skb_unclone(head, GFP_ATOMIC)) 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_has_frag_list(head)) { struct sk_buff *clone; int i, plen = 0; clone = alloc_skb(0, GFP_ATOMIC); if (!clone) goto out_oom; clone->next = head->next; head->next = clone; skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; skb_frag_list_init(head); for (i = 0; i < skb_shinfo(head)->nr_frags; i++) plen += skb_frag_size(&skb_shinfo(head)->frags[i]); 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; add_frag_mem_limit(fq->q.net, clone->truesize); } /* We have to remove fragment header from datagram and to relocate * header in order to calculate ICV correctly. */ nhoff = fq->nhoffset; skb_network_header(head)[nhoff] = skb_transport_header(head)[0]; memmove(head->head + sizeof(struct frag_hdr), head->head, (head->data - head->head) - sizeof(struct frag_hdr)); if (skb_mac_header_was_set(head)) head->mac_header += sizeof(struct frag_hdr); head->network_header += sizeof(struct frag_hdr); skb_reset_transport_header(head); skb_push(head, head->data - skb_network_header(head)); sum_truesize = head->truesize; for (fp = head->next; fp;) { bool headstolen; int delta; struct sk_buff *next = fp->next; sum_truesize += fp->truesize; 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); if (skb_try_coalesce(head, fp, &headstolen, &delta)) { kfree_skb_partial(fp, headstolen); } else { if (!skb_shinfo(head)->frag_list) skb_shinfo(head)->frag_list = fp; head->data_len += fp->len; head->len += fp->len; head->truesize += fp->truesize; } fp = next; } sub_frag_mem_limit(fq->q.net, sum_truesize); head->next = NULL; head->dev = dev; head->tstamp = fq->q.stamp; ipv6_hdr(head)->payload_len = htons(payload_len); ipv6_change_dsfield(ipv6_hdr(head), 0xff, ecn); IP6CB(head)->nhoff = nhoff; IP6CB(head)->flags |= IP6SKB_FRAGMENTED; IP6CB(head)->frag_max_size = fq->q.max_size; /* Yes, and fold redundant checksum back. 8) */ skb_postpush_rcsum(head, skb_network_header(head), skb_network_header_len(head)); rcu_read_lock(); __IP6_INC_STATS(net, __in6_dev_get(dev), IPSTATS_MIB_REASMOKS); rcu_read_unlock(); fq->q.fragments = NULL; fq->q.fragments_tail = NULL; return 1; out_oversize: net_dbg_ratelimited("ip6_frag_reasm: payload len = %d\n", payload_len); goto out_fail; out_oom: net_dbg_ratelimited("ip6_frag_reasm: no memory for reassembly\n"); out_fail: rcu_read_lock(); __IP6_INC_STATS(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS); rcu_read_unlock(); return -1; }
static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb, struct frag_hdr *fhdr, int nhoff) { struct sk_buff *prev, *next; struct net_device *dev; int offset, end, fragsize; struct net *net = dev_net(skb_dst(skb)->dev); u8 ecn; if (fq->q.flags & INET_FRAG_COMPLETE) 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) { __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS); icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, ((u8 *)&fhdr->frag_off - skb_network_header(skb))); return -1; } ecn = ip6_frag_ecn(ipv6_hdr(skb)); 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.flags & INET_FRAG_LAST_IN) && end != fq->q.len)) goto err; fq->q.flags |= INET_FRAG_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 */ __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS); icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, offsetof(struct ipv6hdr, payload_len)); return -1; } if (end > fq->q.len) { /* Some bits beyond end -> corruption. */ if (fq->q.flags & INET_FRAG_LAST_IN) 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)) goto err; if (pskb_trim_rcsum(skb, end - offset)) 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 = fq->q.fragments_tail; if (!prev || FRAG6_CB(prev)->offset < offset) { next = NULL; goto found; } prev = NULL; for (next = fq->q.fragments; next != NULL; next = next->next) { if (FRAG6_CB(next)->offset >= offset) break; /* bingo! */ prev = next; } found: /* RFC5722, Section 4, amended by Errata ID : 3089 * When reassembling an IPv6 datagram, if * one or more its constituent fragments is determined to be an * overlapping fragment, the entire datagram (and any constituent * fragments) MUST be silently discarded. */ /* Check for overlap with preceding fragment. */ if (prev && (FRAG6_CB(prev)->offset + prev->len) > offset) goto discard_fq; /* Look for overlap with succeeding segment. */ if (next && FRAG6_CB(next)->offset < end) goto discard_fq; FRAG6_CB(skb)->offset = offset; /* Insert this fragment in the chain of fragments. */ skb->next = next; if (!next) fq->q.fragments_tail = skb; if (prev) prev->next = skb; else fq->q.fragments = skb; dev = skb->dev; if (dev) { fq->iif = dev->ifindex; skb->dev = NULL; } fq->q.stamp = skb->tstamp; fq->q.meat += skb->len; fq->ecn |= ecn; add_frag_mem_limit(fq->q.net, skb->truesize); fragsize = -skb_network_offset(skb) + skb->len; if (fragsize > fq->q.max_size) fq->q.max_size = fragsize; /* The first fragment. * nhoffset is obtained from the first fragment, of course. */ if (offset == 0) { fq->nhoffset = nhoff; fq->q.flags |= INET_FRAG_FIRST_IN; } if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && fq->q.meat == fq->q.len) { int res; unsigned long orefdst = skb->_skb_refdst; skb->_skb_refdst = 0UL; res = ip6_frag_reasm(fq, prev, dev); skb->_skb_refdst = orefdst; return res; } skb_dst_drop(skb); return -1; discard_fq: inet_frag_kill(&fq->q, &ip6_frags); err: __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMFAILS); kfree_skb(skb); return -1; }
/* Build a new IP datagram from all its fragments. */ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb, struct sk_buff *prev_tail, struct net_device *dev) { struct net *net = container_of(qp->q.net, struct net, ipv4.frags); struct iphdr *iph; struct sk_buff *fp, *head = skb_rb_first(&qp->q.rb_fragments); struct sk_buff **nextp; /* To build frag_list. */ struct rb_node *rbn; int len; int ihlen; int err; u8 ecn; ipq_kill(qp); ecn = ip_frag_ecn_table[qp->ecn]; if (unlikely(ecn == 0xff)) { err = -EINVAL; goto out_fail; } /* Make the one we just received the head. */ if (head != skb) { fp = skb_clone(skb, GFP_ATOMIC); if (!fp) goto out_nomem; FRAG_CB(fp)->next_frag = FRAG_CB(skb)->next_frag; if (RB_EMPTY_NODE(&skb->rbnode)) FRAG_CB(prev_tail)->next_frag = fp; else rb_replace_node(&skb->rbnode, &fp->rbnode, &qp->q.rb_fragments); if (qp->q.fragments_tail == skb) qp->q.fragments_tail = fp; skb_morph(skb, head); FRAG_CB(skb)->next_frag = FRAG_CB(head)->next_frag; rb_replace_node(&head->rbnode, &skb->rbnode, &qp->q.rb_fragments); consume_skb(head); head = skb; } WARN_ON(head->ip_defrag_offset != 0); /* Allocate a new buffer for the datagram. */ ihlen = ip_hdrlen(head); len = ihlen + qp->q.len; err = -E2BIG; if (len > 65535) goto out_oversize; /* Head of list must not be cloned. */ if (skb_unclone(head, GFP_ATOMIC)) goto out_nomem; /* 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_has_frag_list(head)) { struct sk_buff *clone; int i, plen = 0; clone = alloc_skb(0, GFP_ATOMIC); if (!clone) goto out_nomem; skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; skb_frag_list_init(head); for (i = 0; i < skb_shinfo(head)->nr_frags; i++) plen += skb_frag_size(&skb_shinfo(head)->frags[i]); clone->len = clone->data_len = head->data_len - plen; head->truesize += clone->truesize; clone->csum = 0; clone->ip_summed = head->ip_summed; add_frag_mem_limit(qp->q.net, clone->truesize); skb_shinfo(head)->frag_list = clone; nextp = &clone->next; } else { nextp = &skb_shinfo(head)->frag_list; } skb_push(head, head->data - skb_network_header(head)); /* Traverse the tree in order, to build frag_list. */ fp = FRAG_CB(head)->next_frag; rbn = rb_next(&head->rbnode); rb_erase(&head->rbnode, &qp->q.rb_fragments); while (rbn || fp) { /* fp points to the next sk_buff in the current run; * rbn points to the next run. */ /* Go through the current run. */ while (fp) { *nextp = fp; nextp = &fp->next; fp->prev = NULL; memset(&fp->rbnode, 0, sizeof(fp->rbnode)); 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; fp = FRAG_CB(fp)->next_frag; } /* Move to the next run. */ if (rbn) { struct rb_node *rbnext = rb_next(rbn); fp = rb_to_skb(rbn); rb_erase(rbn, &qp->q.rb_fragments); rbn = rbnext; } } sub_frag_mem_limit(qp->q.net, head->truesize); *nextp = NULL; head->next = NULL; head->prev = NULL; head->dev = dev; head->tstamp = qp->q.stamp; IPCB(head)->frag_max_size = max(qp->max_df_size, qp->q.max_size); iph = ip_hdr(head); iph->tot_len = htons(len); iph->tos |= ecn; /* When we set IP_DF on a refragmented skb we must also force a * call to ip_fragment to avoid forwarding a DF-skb of size s while * original sender only sent fragments of size f (where f < s). * * We only set DF/IPSKB_FRAG_PMTU if such DF fragment was the largest * frag seen to avoid sending tiny DF-fragments in case skb was built * from one very small df-fragment and one large non-df frag. */ if (qp->max_df_size == qp->q.max_size) { IPCB(head)->flags |= IPSKB_FRAG_PMTU; iph->frag_off = htons(IP_DF); } else { iph->frag_off = 0; } ip_send_check(iph); __IP_INC_STATS(net, IPSTATS_MIB_REASMOKS); qp->q.fragments = NULL; qp->q.rb_fragments = RB_ROOT; qp->q.fragments_tail = NULL; qp->q.last_run_head = NULL; return 0; out_nomem: net_dbg_ratelimited("queue_glue: no memory for gluing queue %p\n", qp); err = -ENOMEM; goto out_fail; out_oversize: net_info_ratelimited("Oversized IP packet from %pI4\n", &qp->q.key.v4.saddr); out_fail: __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); return err; }
/* Add new segment to existing queue. */ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) { struct net *net = container_of(qp->q.net, struct net, ipv4.frags); struct rb_node **rbn, *parent; struct sk_buff *skb1, *prev_tail; struct net_device *dev; unsigned int fragsize; int flags, offset; int ihl, end; int err = -ENOENT; u8 ecn; if (qp->q.flags & INET_FRAG_COMPLETE) goto err; if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && unlikely(ip_frag_too_far(qp)) && unlikely(err = ip_frag_reinit(qp))) { ipq_kill(qp); goto err; } ecn = ip4_frag_ecn(ip_hdr(skb)->tos); offset = ntohs(ip_hdr(skb)->frag_off); flags = offset & ~IP_OFFSET; offset &= IP_OFFSET; offset <<= 3; /* offset is in 8-byte chunks */ ihl = ip_hdrlen(skb); /* Determine the position of this fragment. */ end = offset + skb->len - skb_network_offset(skb) - ihl; err = -EINVAL; /* Is this the final fragment? */ if ((flags & IP_MF) == 0) { /* If we already have some bits beyond end * or have different end, the segment is corrupted. */ if (end < qp->q.len || ((qp->q.flags & INET_FRAG_LAST_IN) && end != qp->q.len)) goto err; qp->q.flags |= INET_FRAG_LAST_IN; qp->q.len = end; } else { if (end&7) { end &= ~7; if (skb->ip_summed != CHECKSUM_UNNECESSARY) skb->ip_summed = CHECKSUM_NONE; } if (end > qp->q.len) { /* Some bits beyond end -> corruption. */ if (qp->q.flags & INET_FRAG_LAST_IN) goto err; qp->q.len = end; } } if (end == offset) goto err; err = -ENOMEM; if (!pskb_pull(skb, skb_network_offset(skb) + ihl)) goto err; err = pskb_trim_rcsum(skb, end - offset); if (err) goto err; /* Note : skb->rbnode and skb->dev share the same location. */ dev = skb->dev; /* Makes sure compiler wont do silly aliasing games */ barrier(); /* RFC5722, Section 4, amended by Errata ID : 3089 * When reassembling an IPv6 datagram, if * one or more its constituent fragments is determined to be an * overlapping fragment, the entire datagram (and any constituent * fragments) MUST be silently discarded. * * We do the same here for IPv4 (and increment an snmp counter). */ /* Find out where to put this fragment. */ prev_tail = qp->q.fragments_tail; if (!prev_tail) ip4_frag_create_run(&qp->q, skb); /* First fragment. */ else if (prev_tail->ip_defrag_offset + prev_tail->len < end) { /* This is the common case: skb goes to the end. */ /* Detect and discard overlaps. */ if (offset < prev_tail->ip_defrag_offset + prev_tail->len) goto discard_qp; if (offset == prev_tail->ip_defrag_offset + prev_tail->len) ip4_frag_append_to_last_run(&qp->q, skb); else ip4_frag_create_run(&qp->q, skb); } else { /* Binary search. Note that skb can become the first fragment, * but not the last (covered above). */ rbn = &qp->q.rb_fragments.rb_node; do { parent = *rbn; skb1 = rb_to_skb(parent); if (end <= skb1->ip_defrag_offset) rbn = &parent->rb_left; else if (offset >= skb1->ip_defrag_offset + FRAG_CB(skb1)->frag_run_len) rbn = &parent->rb_right; else /* Found an overlap with skb1. */ goto discard_qp; } while (*rbn); /* Here we have parent properly set, and rbn pointing to * one of its NULL left/right children. Insert skb. */ ip4_frag_init_run(skb); rb_link_node(&skb->rbnode, parent, rbn); rb_insert_color(&skb->rbnode, &qp->q.rb_fragments); } if (dev) qp->iif = dev->ifindex; skb->ip_defrag_offset = offset; qp->q.stamp = skb->tstamp; qp->q.meat += skb->len; qp->ecn |= ecn; add_frag_mem_limit(qp->q.net, skb->truesize); if (offset == 0) qp->q.flags |= INET_FRAG_FIRST_IN; fragsize = skb->len + ihl; if (fragsize > qp->q.max_size) qp->q.max_size = fragsize; if (ip_hdr(skb)->frag_off & htons(IP_DF) && fragsize > qp->max_df_size) qp->max_df_size = fragsize; if (qp->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && qp->q.meat == qp->q.len) { unsigned long orefdst = skb->_skb_refdst; skb->_skb_refdst = 0UL; err = ip_frag_reasm(qp, skb, prev_tail, dev); skb->_skb_refdst = orefdst; return err; } skb_dst_drop(skb); return -EINPROGRESS; discard_qp: inet_frag_kill(&qp->q); err = -EINVAL; __IP_INC_STATS(net, IPSTATS_MIB_REASM_OVERLAPS); err: kfree_skb(skb); return err; }