--- /dev/null
+/*
+ * 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 int zero;
+
+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 int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &zero,
+ .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 int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_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.sysctl.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.sysctl.frags_hdr->ctl_table_arg;
+ unregister_net_sysctl_table(net->nf_frag.sysctl.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 unsigned int nf_hash_frag(__be32 id, const struct in6_addr *saddr,
+ const struct in6_addr *daddr)
+{
+ net_get_random_once(&nf_frags.rnd, sizeof(nf_frags.rnd));
+ return jhash_3words(ipv6_addr_hash(saddr), ipv6_addr_hash(daddr),
+ (__force u32)id, nf_frags.rnd);
+}
+
+
+static unsigned int nf_hashfn(const struct inet_frag_queue *q)
+{
+ const struct frag_queue *nq;
+
+ nq = container_of(q, struct frag_queue, q);
+ return nf_hash_frag(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);
+}
+
+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, &nf_frags);
+}
+
+/* Creation primitives. */
+static inline struct frag_queue *fq_find(struct net *net, __be32 id,
+ u32 user, struct in6_addr *src,
+ struct in6_addr *dst, u8 ecn)
+{
+ 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;
+ arg.ecn = ecn;
+
+ local_bh_disable();
+ hash = nf_hash_frag(id, src, dst);
+
+ q = inet_frag_find(&net->nf_frag.frags, &nf_frags, &arg, hash);
+ local_bh_enable();
+ if (IS_ERR_OR_NULL(q)) {
+ inet_frag_maybe_warn_overflow(q, pr_fmt());
+ 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, 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, &nf_frags);
+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, &nf_frags);
+
+ 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, 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;
+ }
+ sub_frag_mem_limit(&fq->q, 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.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 sk_buff *skb, u32 user)
+{
+ struct sk_buff *clone;
+ struct net_device *dev = skb->dev;
+ struct net *net = skb_dst(skb) ? dev_net(skb_dst(skb)->dev)
+ : dev_net(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);
+
+ fq = fq_find(net, fhdr->identification, user, &hdr->saddr, &hdr->daddr,
+ ip6_frag_ecn(hdr));
+ 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, &nf_frags);
+ 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, &nf_frags);
+ return ret_skb;
+
+ret_orig:
+ kfree_skb(clone);
+ return skb;
+}
+
+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;
+ }
+}
+
+static int nf_ct_net_init(struct net *net)
+{
+ 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;
+ inet_frags_init_net(&net->nf_frag.frags);
+
+ return nf_ct_frag6_sysctl_register(net);
+}
+
+static void nf_ct_net_exit(struct net *net)
+{
+ nf_ct_frags6_sysctl_unregister(net);
+ inet_frags_exit_net(&net->nf_frag.frags, &nf_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.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 frag_queue);
+ nf_frags.match = ip6_frag_match;
+ nf_frags.frag_expire = nf_ct_frag6_expire;
+ nf_frags.frags_cache_name = nf_frags_cache_name;
+ 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);
+}
Code Review / kvmfornfv.git / blobdiff