| /* |
| * 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/ipv6_frag.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"; |
| |
| 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_ct_frag6_expire(struct timer_list *t) |
| { |
| struct inet_frag_queue *frag = from_timer(frag, t, timer); |
| struct frag_queue *fq; |
| struct net *net; |
| |
| fq = container_of(frag, struct frag_queue, q); |
| net = container_of(fq->q.net, struct net, nf_frag.frags); |
| |
| ip6frag_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 -EINVAL; |
| } |
| |
| 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"); |
| inet_frag_kill(&fq->q); |
| return -EPROTO; |
| } |
| 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 || prev->ip_defrag_offset < offset) { |
| next = NULL; |
| goto found; |
| } |
| prev = NULL; |
| for (next = fq->q.fragments; next != NULL; next = next->next) { |
| if (next->ip_defrag_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 && |
| (prev->ip_defrag_offset + prev->len) > offset) |
| goto discard_fq; |
| |
| /* Look for overlap with succeeding segment. */ |
| if (next && next->ip_defrag_offset < end) |
| goto discard_fq; |
| |
| /* Note : skb->ip_defrag_offset and skb->dev share the same location */ |
| if (skb->dev) |
| fq->iif = skb->dev->ifindex; |
| /* Makes sure compiler wont do silly aliasing games */ |
| barrier(); |
| skb->ip_defrag_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; |
| |
| 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 -EINVAL; |
| } |
| |
| /* |
| * Check if this packet is complete. |
| * |
| * 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. |
| * |
| * returns true if *prev skb has been transformed into the reassembled |
| * skb, false otherwise. |
| */ |
| static bool |
| nf_ct_frag6_reasm(struct frag_queue *fq, struct sk_buff *prev, struct net_device *dev) |
| { |
| struct sk_buff *fp, *head = fq->q.fragments; |
| int payload_len; |
| u8 ecn; |
| |
| inet_frag_kill(&fq->q); |
| |
| WARN_ON(head == NULL); |
| WARN_ON(head->ip_defrag_offset != 0); |
| |
| ecn = ip_frag_ecn_table[fq->ecn]; |
| if (unlikely(ecn == 0xff)) |
| return false; |
| |
| /* 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) { |
| net_dbg_ratelimited("nf_ct_frag6_reasm: payload len = %d\n", |
| payload_len); |
| return false; |
| } |
| |
| /* Head of list must not be cloned. */ |
| if (skb_unclone(head, GFP_ATOMIC)) |
| return false; |
| |
| /* 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) |
| return false; |
| |
| 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); |
| } |
| |
| /* morph head into last received skb: prev. |
| * |
| * This allows callers of ipv6 conntrack defrag to continue |
| * to use the last skb(frag) passed into the reasm engine. |
| * The last skb frag 'silently' turns into the full reassembled skb. |
| * |
| * Since prev is also part of q->fragments we have to clone it first. |
| */ |
| if (head != prev) { |
| struct sk_buff *iter; |
| |
| fp = skb_clone(prev, GFP_ATOMIC); |
| if (!fp) |
| return false; |
| |
| fp->next = prev->next; |
| |
| iter = head; |
| while (iter) { |
| if (iter->next == prev) { |
| iter->next = fp; |
| break; |
| } |
| iter = iter->next; |
| } |
| |
| skb_morph(prev, head); |
| prev->next = head->next; |
| consume_skb(head); |
| head = prev; |
| } |
| |
| /* 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; |
| |
| return true; |
| } |
| |
| /* |
| * 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; |
| } |
| |
| int nf_ct_frag6_gather(struct net *net, struct sk_buff *skb, u32 user) |
| { |
| u16 savethdr = skb->transport_header; |
| struct net_device *dev = skb->dev; |
| int fhoff, nhoff, ret; |
| struct frag_hdr *fhdr; |
| struct frag_queue *fq; |
| struct ipv6hdr *hdr; |
| u8 prevhdr; |
| |
| /* Jumbo payload inhibits frag. header */ |
| if (ipv6_hdr(skb)->payload_len == 0) { |
| pr_debug("payload len = 0\n"); |
| return 0; |
| } |
| |
| if (find_prev_fhdr(skb, &prevhdr, &nhoff, &fhoff) < 0) |
| return 0; |
| |
| if (!pskb_may_pull(skb, fhoff + sizeof(*fhdr))) |
| return -ENOMEM; |
| |
| skb_set_transport_header(skb, fhoff); |
| hdr = ipv6_hdr(skb); |
| fhdr = (struct frag_hdr *)skb_transport_header(skb); |
| |
| if (skb->len - skb_network_offset(skb) < IPV6_MIN_MTU && |
| fhdr->frag_off & htons(IP6_MF)) |
| return -EINVAL; |
| |
| 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"); |
| return -ENOMEM; |
| } |
| |
| spin_lock_bh(&fq->q.lock); |
| |
| ret = nf_ct_frag6_queue(fq, skb, fhdr, nhoff); |
| if (ret < 0) { |
| if (ret == -EPROTO) { |
| skb->transport_header = savethdr; |
| ret = 0; |
| } |
| goto out_unlock; |
| } |
| |
| /* after queue has assumed skb ownership, only 0 or -EINPROGRESS |
| * must be returned. |
| */ |
| ret = -EINPROGRESS; |
| if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && |
| fq->q.meat == fq->q.len && |
| nf_ct_frag6_reasm(fq, skb, dev)) |
| ret = 0; |
| else |
| skb_dst_drop(skb); |
| |
| out_unlock: |
| spin_unlock_bh(&fq->q.lock); |
| inet_frag_put(&fq->q); |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(nf_ct_frag6_gather); |
| |
| 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, |
| }; |
| |
| static const struct rhashtable_params nfct_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 nf_ct_frag6_init(void) |
| { |
| int ret = 0; |
| |
| nf_frags.constructor = ip6frag_init; |
| nf_frags.destructor = NULL; |
| 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 = nfct_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); |
| } |