diff options
| author | Eric Dumazet <edumazet@google.com> | 2014-05-29 08:45:14 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-06-26 15:10:28 -0400 |
| commit | 0a4474aaad97472efcd10a3e8d897d5798206f0e (patch) | |
| tree | eedca98333d8d5ec4a09195faadef3fd6e2b52c2 | |
| parent | d0e49724c557974bb109ffee5cd3eb4864b8cc1d (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.h | 9 | ||||
| -rw-r--r-- | net/ipv6/ip6_output.c | 11 |
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 *)) |