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authorEric Dumazet <edumazet@google.com>2014-05-29 08:45:14 -0700
committerDavid S. Miller <davem@davemloft.net>2014-06-02 14:09:28 -0700
commit39c36094d78c39e038c1e499b2364e13bce36f54 (patch)
treefac76f2e1c8968c74556cc68c1920da58c6bf3dd
parentfc0d6e9cd0aefbe5de5ebafb1805f2c59539725b (diff)
net: fix inet_getid() and ipv6_select_ident() bugs
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>
-rw-r--r--include/net/inetpeer.h9
-rw-r--r--net/ipv6/output_core.c11
2 files changed, 4 insertions, 16 deletions
diff --git a/include/net/inetpeer.h b/include/net/inetpeer.h
index 6efe73c79c52..058271bde27a 100644
--- a/include/net/inetpeer.h
+++ b/include/net/inetpeer.h
@@ -177,16 +177,9 @@ 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/output_core.c b/net/ipv6/output_core.c
index 6313abd53c9d..56596ce390a1 100644
--- a/net/ipv6/output_core.c
+++ b/net/ipv6/output_core.c
@@ -12,7 +12,7 @@ void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt)
{
static atomic_t ipv6_fragmentation_id;
struct in6_addr addr;
- int old, new;
+ int ident;
#if IS_ENABLED(CONFIG_IPV6)
struct inet_peer *peer;
@@ -26,15 +26,10 @@ void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt)
return;
}
#endif
- do {
- old = atomic_read(&ipv6_fragmentation_id);
- new = old + 1;
- if (!new)
- new = 1;
- } while (atomic_cmpxchg(&ipv6_fragmentation_id, old, new) != old);
+ ident = atomic_inc_return(&ipv6_fragmentation_id);
addr = rt->rt6i_dst.addr;
- addr.s6_addr32[0] ^= (__force __be32)new;
+ addr.s6_addr32[0] ^= (__force __be32)ident;
fhdr->identification = htonl(secure_ipv6_id(addr.s6_addr32));
}
EXPORT_SYMBOL(ipv6_select_ident);

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