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authorEric Dumazet <edumazet@google.com>2014-05-29 08:45:14 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-06-26 15:10:28 -0400
commit0a4474aaad97472efcd10a3e8d897d5798206f0e (patch)
treeeedca98333d8d5ec4a09195faadef3fd6e2b52c2
parentd0e49724c557974bb109ffee5cd3eb4864b8cc1d (diff)
net: fix inet_getid() and ipv6_select_ident() bugs
[ Upstream commit 39c36094d78c39e038c1e499b2364e13bce36f54 ] I noticed we were sending wrong IPv4 ID in TCP flows when MTU discovery is disabled. Note how GSO/TSO packets do not have monotonically incrementing ID. 06:37:41.575531 IP (id 14227, proto: TCP (6), length: 4396) 06:37:41.575534 IP (id 14272, proto: TCP (6), length: 65212) 06:37:41.575544 IP (id 14312, proto: TCP (6), length: 57972) 06:37:41.575678 IP (id 14317, proto: TCP (6), length: 7292) 06:37:41.575683 IP (id 14361, proto: TCP (6), length: 63764) It appears I introduced this bug in linux-3.1. inet_getid() must return the old value of peer->ip_id_count, not the new one. Lets revert this part, and remove the prevention of a null identification field in IPv6 Fragment Extension Header, which is dubious and not even done properly. Fixes: 87c48fa3b463 ("ipv6: make fragment identifications less predictable") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--include/net/inetpeer.h9
-rw-r--r--net/ipv6/ip6_output.c11
2 files changed, 4 insertions, 16 deletions
diff --git a/include/net/inetpeer.h b/include/net/inetpeer.h
index 2040bff945d4..2d643649f0f8 100644
--- a/include/net/inetpeer.h
+++ b/include/net/inetpeer.h
@@ -114,16 +114,9 @@ static inline void inet_peer_refcheck(const struct inet_peer *p)
/* can be called with or without local BH being disabled */
static inline int inet_getid(struct inet_peer *p, int more)
{
- int old, new;
more++;
inet_peer_refcheck(p);
- do {
- old = atomic_read(&p->ip_id_count);
- new = old + more;
- if (!new)
- new = 1;
- } while (atomic_cmpxchg(&p->ip_id_count, old, new) != old);
- return new;
+ return atomic_add_return(more, &p->ip_id_count) - more;
}
#endif /* _NET_INETPEER_H */
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 5a2d819d8262..077b9a3f8d25 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -611,7 +611,7 @@ int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt)
{
static atomic_t ipv6_fragmentation_id;
- int old, new;
+ int ident;
if (rt && !(rt->dst.flags & DST_NOPEER)) {
struct inet_peer *peer;
@@ -624,13 +624,8 @@ void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt)
return;
}
}
- do {
- old = atomic_read(&ipv6_fragmentation_id);
- new = old + 1;
- if (!new)
- new = 1;
- } while (atomic_cmpxchg(&ipv6_fragmentation_id, old, new) != old);
- fhdr->identification = htonl(new);
+ ident = atomic_inc_return(&ipv6_fragmentation_id);
+ fhdr->identification = htonl(ident);
}
int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))