netfilter: nf_conntrack_reasm: add fast path for in-order fragments
As the fragments are sent in order in most of OSes, such as Windows, Darwin and
FreeBSD, it is likely the new fragments are at the end of the inet_frag_queue.
In the fast path, we check if the skb at the end of the inet_frag_queue is the
prev we expect.
Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index 9254008..098a050 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -269,6 +269,11 @@
* 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)
@@ -276,6 +281,7 @@
prev = next;
}
+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.
@@ -341,6 +347,8 @@
/* Insert this fragment in the chain of fragments. */
skb->next = next;
+ if (!next)
+ fq->q.fragments_tail = skb;
if (prev)
prev->next = skb;
else
@@ -464,6 +472,7 @@
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;
