| /* |
| * 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 <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/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> |
| |
| |
| 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 */ |
| u32 user; |
| struct in6_addr saddr; |
| struct in6_addr daddr; |
| |
| unsigned int csum; |
| __u16 nhoffset; |
| }; |
| |
| static struct inet_frags nf_frags; |
| static struct netns_frags nf_init_frags; |
| |
| #ifdef CONFIG_SYSCTL |
| struct ctl_table nf_ct_ipv6_sysctl_table[] = { |
| { |
| .procname = "nf_conntrack_frag6_timeout", |
| .data = &nf_init_frags.timeout, |
| .maxlen = sizeof(unsigned int), |
| .mode = 0644, |
| .proc_handler = proc_dointvec_jiffies, |
| }, |
| { |
| .procname = "nf_conntrack_frag6_low_thresh", |
| .data = &nf_init_frags.low_thresh, |
| .maxlen = sizeof(unsigned int), |
| .mode = 0644, |
| .proc_handler = proc_dointvec, |
| }, |
| { |
| .procname = "nf_conntrack_frag6_high_thresh", |
| .data = &nf_init_frags.high_thresh, |
| .maxlen = sizeof(unsigned int), |
| .mode = 0644, |
| .proc_handler = proc_dointvec, |
| }, |
| { } |
| }; |
| #endif |
| |
| static unsigned int nf_hashfn(struct inet_frag_queue *q) |
| { |
| const struct nf_ct_frag6_queue *nq; |
| |
| nq = container_of(q, struct nf_ct_frag6_queue, q); |
| return inet6_hash_frag(nq->id, &nq->saddr, &nq->daddr, nf_frags.rnd); |
| } |
| |
| 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_init_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) |
| { |
| local_bh_disable(); |
| inet_frag_evictor(&nf_init_frags, &nf_frags); |
| local_bh_enable(); |
| } |
| |
| 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 & INET_FRAG_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, u32 user, 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.user = user; |
| arg.src = src; |
| arg.dst = dst; |
| |
| read_lock_bh(&nf_frags.lock); |
| hash = inet6_hash_frag(id, src, dst, nf_frags.rnd); |
| |
| q = inet_frag_find(&nf_init_frags, &nf_frags, &arg, hash); |
| local_bh_enable(); |
| 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, |
| const struct frag_hdr *fhdr, int nhoff) |
| { |
| struct sk_buff *prev, *next; |
| int offset, end; |
| |
| if (fq->q.last_in & INET_FRAG_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 & INET_FRAG_LAST_IN) && end != fq->q.len)) { |
| pr_debug("already received last fragment\n"); |
| goto err; |
| } |
| fq->q.last_in |= 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.last_in & 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 = 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_init_frags.mem); |
| |
| /* The first fragment. |
| * nhoffset is obtained from the first fragment, of course. |
| */ |
| if (offset == 0) { |
| fq->nhoffset = nhoff; |
| fq->q.last_in |= INET_FRAG_FIRST_IN; |
| } |
| write_lock(&nf_frags.lock); |
| list_move_tail(&fq->q.lru_list, &nf_init_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); |
| |
| WARN_ON(head == NULL); |
| WARN_ON(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_has_frags(head)) { |
| 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_frag_list_init(head); |
| 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_init_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_init_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_init_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 (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: |
| 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 (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 sk_buff *skb, u32 user) |
| { |
| 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 (atomic_read(&nf_init_frags.mem) > nf_init_frags.high_thresh) |
| nf_ct_frag6_evictor(); |
| |
| fq = fq_find(fhdr->identification, user, &hdr->saddr, &hdr->daddr); |
| 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"); |
| fq_put(fq); |
| goto ret_orig; |
| } |
| |
| if (fq->q.last_in == (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); |
| |
| 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(NFPROTO_IPV6, hooknum, s, in, out, okfn, |
| NF_IP6_PRI_CONNTRACK_DEFRAG + 1); |
| s = s2; |
| } |
| nf_conntrack_put_reasm(skb); |
| } |
| |
| int nf_ct_frag6_init(void) |
| { |
| 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; |
| nf_frags.secret_interval = 10 * 60 * HZ; |
| nf_init_frags.timeout = IPV6_FRAG_TIMEOUT; |
| nf_init_frags.high_thresh = IPV6_FRAG_HIGH_THRESH; |
| nf_init_frags.low_thresh = IPV6_FRAG_LOW_THRESH; |
| inet_frags_init_net(&nf_init_frags); |
| inet_frags_init(&nf_frags); |
| |
| return 0; |
| } |
| |
| void nf_ct_frag6_cleanup(void) |
| { |
| inet_frags_fini(&nf_frags); |
| |
| nf_init_frags.low_thresh = 0; |
| nf_ct_frag6_evictor(); |
| } |