aboutsummaryrefslogtreecommitdiffstats
path: root/net
diff options
context:
space:
mode:
authorNicolas Dichtel <nicolas.dichtel@6wind.com>2010-09-03 05:13:07 +0000
committerDavid S. Miller <davem@davemloft.net>2010-09-07 13:57:21 -0700
commit1ee89bd0fe72e381c8e4ef887d53c19c8adc6c93 (patch)
tree3a73d6913b51dc91114443c5af2a1d44c59735c6 /net
parent70789d7052239992824628db8133de08dc78e593 (diff)
downloadmrst-s0i3-test-1ee89bd0fe72e381c8e4ef887d53c19c8adc6c93.tar.gz
mrst-s0i3-test-1ee89bd0fe72e381c8e4ef887d53c19c8adc6c93.tar.xz
mrst-s0i3-test-1ee89bd0fe72e381c8e4ef887d53c19c8adc6c93.zip
netfilter: discard overlapping IPv6 fragment
RFC5722 prohibits reassembling IPv6 fragments when some data overlaps. Bug spotted by Zhang Zuotao <zuotao.zhang@6wind.com>. Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ipv6/netfilter/nf_conntrack_reasm.c80
1 files changed, 15 insertions, 65 deletions
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index 13ef5bc05cf..578f3c1a16d 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -113,14 +113,6 @@ static void nf_skb_free(struct sk_buff *skb)
kfree_skb(NFCT_FRAG6_CB(skb)->orig);
}
-/* Memory Tracking Functions. */
-static void frag_kfree_skb(struct sk_buff *skb)
-{
- 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)
@@ -282,66 +274,22 @@ static int nf_ct_frag6_queue(struct nf_ct_frag6_queue *fq, struct sk_buff *skb,
}
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 = (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.
+ /* 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.
*/
- 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;
+ /* Check for overlap with preceding fragment. */
+ if (prev &&
+ (NFCT_FRAG6_CB(prev)->offset + prev->len) - offset > 0)
+ goto discard_fq;
- if (prev)
- prev->next = next;
- else
- fq->q.fragments = next;
-
- fq->q.meat -= free_it->len;
- frag_kfree_skb(free_it);
- }
- }
+ /* Look for overlap with succeeding segment. */
+ if (next && NFCT_FRAG6_CB(next)->offset < end)
+ goto discard_fq;
NFCT_FRAG6_CB(skb)->offset = offset;
@@ -371,6 +319,8 @@ found:
write_unlock(&nf_frags.lock);
return 0;
+discard_fq:
+ fq_kill(fq);
err:
return -1;
}