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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.
- */
- #define pr_fmt(fmt) "IPv6-nf: " fmt
- #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/slab.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 <net/inet_ecn.h>
- #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
- #include <linux/sysctl.h>
- #include <linux/netfilter.h>
- #include <linux/netfilter_ipv6.h>
- #include <linux/kernel.h>
- #include <linux/module.h>
- #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
- static const char nf_frags_cache_name[] = "nf-frags";
- 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))
- static struct inet_frags nf_frags;
- #ifdef CONFIG_SYSCTL
- static struct ctl_table nf_ct_frag6_sysctl_table[] = {
- {
- .procname = "nf_conntrack_frag6_timeout",
- .data = &init_net.nf_frag.frags.timeout,
- .maxlen = sizeof(unsigned int),
- .mode = 0644,
- .proc_handler = proc_dointvec_jiffies,
- },
- {
- .procname = "nf_conntrack_frag6_low_thresh",
- .data = &init_net.nf_frag.frags.low_thresh,
- .maxlen = sizeof(unsigned long),
- .mode = 0644,
- .proc_handler = proc_doulongvec_minmax,
- .extra2 = &init_net.nf_frag.frags.high_thresh
- },
- {
- .procname = "nf_conntrack_frag6_high_thresh",
- .data = &init_net.nf_frag.frags.high_thresh,
- .maxlen = sizeof(unsigned long),
- .mode = 0644,
- .proc_handler = proc_doulongvec_minmax,
- .extra1 = &init_net.nf_frag.frags.low_thresh
- },
- { }
- };
- static int nf_ct_frag6_sysctl_register(struct net *net)
- {
- struct ctl_table *table;
- struct ctl_table_header *hdr;
- table = nf_ct_frag6_sysctl_table;
- if (!net_eq(net, &init_net)) {
- table = kmemdup(table, sizeof(nf_ct_frag6_sysctl_table),
- GFP_KERNEL);
- if (table == NULL)
- goto err_alloc;
- table[0].data = &net->nf_frag.frags.timeout;
- table[1].data = &net->nf_frag.frags.low_thresh;
- table[1].extra2 = &net->nf_frag.frags.high_thresh;
- table[2].data = &net->nf_frag.frags.high_thresh;
- table[2].extra1 = &net->nf_frag.frags.low_thresh;
- table[2].extra2 = &init_net.nf_frag.frags.high_thresh;
- }
- hdr = register_net_sysctl(net, "net/netfilter", table);
- if (hdr == NULL)
- goto err_reg;
- net->nf_frag_frags_hdr = hdr;
- return 0;
- err_reg:
- if (!net_eq(net, &init_net))
- kfree(table);
- err_alloc:
- return -ENOMEM;
- }
- static void __net_exit nf_ct_frags6_sysctl_unregister(struct net *net)
- {
- struct ctl_table *table;
- table = net->nf_frag_frags_hdr->ctl_table_arg;
- unregister_net_sysctl_table(net->nf_frag_frags_hdr);
- if (!net_eq(net, &init_net))
- kfree(table);
- }
- #else
- static int nf_ct_frag6_sysctl_register(struct net *net)
- {
- return 0;
- }
- static void __net_exit nf_ct_frags6_sysctl_unregister(struct net *net)
- {
- }
- #endif
- static inline u8 ip6_frag_ecn(const struct ipv6hdr *ipv6h)
- {
- return 1 << (ipv6_get_dsfield(ipv6h) & INET_ECN_MASK);
- }
- static void nf_skb_free(struct sk_buff *skb)
- {
- if (NFCT_FRAG6_CB(skb)->orig)
- kfree_skb(NFCT_FRAG6_CB(skb)->orig);
- }
- static void nf_ct_frag6_expire(unsigned long data)
- {
- struct frag_queue *fq;
- struct net *net;
- fq = container_of((struct inet_frag_queue *)data, struct frag_queue, q);
- net = container_of(fq->q.net, struct net, nf_frag.frags);
- ip6_expire_frag_queue(net, fq);
- }
- /* Creation primitives. */
- static struct frag_queue *fq_find(struct net *net, __be32 id, u32 user,
- const struct ipv6hdr *hdr, int iif)
- {
- struct frag_v6_compare_key key = {
- .id = id,
- .saddr = hdr->saddr,
- .daddr = hdr->daddr,
- .user = user,
- .iif = iif,
- };
- struct inet_frag_queue *q;
- q = inet_frag_find(&net->nf_frag.frags, &key);
- if (!q)
- return NULL;
- return container_of(q, struct frag_queue, q);
- }
- static int nf_ct_frag6_queue(struct frag_queue *fq, struct sk_buff *skb,
- const struct frag_hdr *fhdr, int nhoff)
- {
- struct sk_buff *prev, *next;
- unsigned int payload_len;
- int offset, end;
- u8 ecn;
- if (fq->q.flags & INET_FRAG_COMPLETE) {
- pr_debug("Already completed\n");
- goto err;
- }
- payload_len = ntohs(ipv6_hdr(skb)->payload_len);
- offset = ntohs(fhdr->frag_off) & ~0x7;
- end = offset + (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;
- }
- 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)) {
- pr_debug("already received last fragment\n");
- 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
- */
- 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.flags & INET_FRAG_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 = fq->q.fragments_tail;
- if (!prev || NFCT_FRAG6_CB(prev)->offset < offset) {
- next = NULL;
- goto found;
- }
- prev = NULL;
- for (next = fq->q.fragments; next != NULL; next = next->next) {
- if (NFCT_FRAG6_CB(next)->offset >= offset)
- break; /* bingo! */
- prev = next;
- }
- found:
- /* RFC5722, Section 4:
- * 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, including those not yet received) MUST be silently
- * discarded.
- */
- /* Check for overlap with preceding fragment. */
- if (prev &&
- (NFCT_FRAG6_CB(prev)->offset + prev->len) > offset)
- goto discard_fq;
- /* Look for overlap with succeeding segment. */
- if (next && NFCT_FRAG6_CB(next)->offset < end)
- goto discard_fq;
- NFCT_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;
- if (skb->dev) {
- fq->iif = skb->dev->ifindex;
- skb->dev = NULL;
- }
- fq->q.stamp = skb->tstamp;
- fq->q.meat += skb->len;
- fq->ecn |= ecn;
- if (payload_len > fq->q.max_size)
- fq->q.max_size = payload_len;
- add_frag_mem_limit(fq->q.net, skb->truesize);
- /* 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;
- }
- return 0;
- discard_fq:
- inet_frag_kill(&fq->q);
- 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 frag_queue *fq, struct net_device *dev)
- {
- struct sk_buff *fp, *op, *head = fq->q.fragments;
- int payload_len;
- u8 ecn;
- inet_frag_kill(&fq->q);
- WARN_ON(head == NULL);
- WARN_ON(NFCT_FRAG6_CB(head)->offset != 0);
- ecn = ip_frag_ecn_table[fq->ecn];
- if (unlikely(ecn == 0xff))
- goto out_fail;
- /* 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_unclone(head, 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_has_frag_list(head)) {
- struct sk_buff *clone;
- int i, plen = 0;
- clone = alloc_skb(0, GFP_ATOMIC);
- if (clone == NULL)
- 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;
- NFCT_FRAG6_CB(clone)->orig = NULL;
- 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. */
- 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));
- 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;
- fp->sk = NULL;
- }
- sub_frag_mem_limit(fq->q.net, head->truesize);
- head->ignore_df = 1;
- 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)->frag_max_size = sizeof(struct ipv6hdr) + fq->q.max_size;
- /* 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;
- fq->q.rb_fragments = RB_ROOT;
- fq->q.fragments_tail = NULL;
- /* all original skbs are linked into the NFCT_FRAG6_CB(head).orig */
- fp = skb_shinfo(head)->frag_list;
- if (fp && 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:
- net_dbg_ratelimited("nf_ct_frag6_reasm: payload len = %d\n",
- payload_len);
- goto out_fail;
- out_oom:
- net_dbg_ratelimited("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 (nexthdr == NEXTHDR_NONE) {
- pr_debug("next header is none\n");
- return -1;
- }
- if (len < (int)sizeof(struct ipv6_opt_hdr)) {
- pr_debug("too short\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 net *net, struct sk_buff *skb, u32 user)
- {
- struct sk_buff *clone;
- struct net_device *dev = skb->dev;
- struct frag_hdr *fhdr;
- struct frag_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 (clone->len - skb_network_offset(clone) < IPV6_MIN_MTU &&
- fhdr->frag_off & htons(IP6_MF))
- goto ret_orig;
- skb_orphan(skb);
- fq = fq_find(net, fhdr->identification, user, hdr,
- skb->dev ? skb->dev->ifindex : 0);
- if (fq == NULL) {
- pr_debug("Can't find and can't create new queue\n");
- goto ret_orig;
- }
- spin_lock_bh(&fq->q.lock);
- if (nf_ct_frag6_queue(fq, clone, fhdr, nhoff) < 0) {
- spin_unlock_bh(&fq->q.lock);
- pr_debug("Can't insert skb to queue\n");
- inet_frag_put(&fq->q);
- goto ret_orig;
- }
- if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_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_bh(&fq->q.lock);
- inet_frag_put(&fq->q);
- return ret_skb;
- ret_orig:
- kfree_skb(clone);
- return skb;
- }
- EXPORT_SYMBOL_GPL(nf_ct_frag6_gather);
- void nf_ct_frag6_consume_orig(struct sk_buff *skb)
- {
- struct sk_buff *s, *s2;
- for (s = NFCT_FRAG6_CB(skb)->orig; s;) {
- s2 = s->next;
- s->next = NULL;
- consume_skb(s);
- s = s2;
- }
- }
- EXPORT_SYMBOL_GPL(nf_ct_frag6_consume_orig);
- static int nf_ct_net_init(struct net *net)
- {
- int res;
- net->nf_frag.frags.high_thresh = IPV6_FRAG_HIGH_THRESH;
- net->nf_frag.frags.low_thresh = IPV6_FRAG_LOW_THRESH;
- net->nf_frag.frags.timeout = IPV6_FRAG_TIMEOUT;
- net->nf_frag.frags.f = &nf_frags;
- res = inet_frags_init_net(&net->nf_frag.frags);
- if (res < 0)
- return res;
- res = nf_ct_frag6_sysctl_register(net);
- if (res < 0)
- inet_frags_exit_net(&net->nf_frag.frags);
- return res;
- }
- static void nf_ct_net_exit(struct net *net)
- {
- nf_ct_frags6_sysctl_unregister(net);
- inet_frags_exit_net(&net->nf_frag.frags);
- }
- static struct pernet_operations nf_ct_net_ops = {
- .init = nf_ct_net_init,
- .exit = nf_ct_net_exit,
- };
- int nf_ct_frag6_init(void)
- {
- int ret = 0;
- nf_frags.constructor = ip6_frag_init;
- nf_frags.destructor = NULL;
- nf_frags.skb_free = nf_skb_free;
- nf_frags.qsize = sizeof(struct frag_queue);
- nf_frags.frag_expire = nf_ct_frag6_expire;
- nf_frags.frags_cache_name = nf_frags_cache_name;
- nf_frags.rhash_params = ip6_rhash_params;
- ret = inet_frags_init(&nf_frags);
- if (ret)
- goto out;
- ret = register_pernet_subsys(&nf_ct_net_ops);
- if (ret)
- inet_frags_fini(&nf_frags);
- out:
- return ret;
- }
- void nf_ct_frag6_cleanup(void)
- {
- unregister_pernet_subsys(&nf_ct_net_ops);
- inet_frags_fini(&nf_frags);
- }
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