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authorEric Dumazet <eric.dumazet@gmail.com>2011-07-21 21:25:58 -0700
committerDavid S. Miller <davem@davemloft.net>2011-07-21 21:25:58 -0700
commit87c48fa3b4630905f98268dde838ee43626a060c (patch)
tree1374b52ed0514682f836cfa0a6a683eb549c9613 /include/net/inetpeer.h
parent21efcfa0ff27776902a8a15e810147be4d937d69 (diff)
ipv6: make fragment identifications less predictable
IPv6 fragment identification generation is way beyond what we use for IPv4 : It uses a single generator. Its not scalable and allows DOS attacks. Now inetpeer is IPv6 aware, we can use it to provide a more secure and scalable frag ident generator (per destination, instead of system wide) This patch : 1) defines a new secure_ipv6_id() helper 2) extends inet_getid() to provide 32bit results 3) extends ipv6_select_ident() with a new dest parameter Reported-by: Fernando Gont <fernando@gont.com.ar> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/inetpeer.h')
-rw-r--r--include/net/inetpeer.h13
1 files changed, 10 insertions, 3 deletions
diff --git a/include/net/inetpeer.h b/include/net/inetpeer.h
index 39d123081e7e..4233e6f9841d 100644
--- a/include/net/inetpeer.h
+++ b/include/net/inetpeer.h
@@ -71,7 +71,7 @@ static inline bool inet_metrics_new(const struct inet_peer *p)
}
/* can be called with or without local BH being disabled */
-struct inet_peer *inet_getpeer(struct inetpeer_addr *daddr, int create);
+struct inet_peer *inet_getpeer(const struct inetpeer_addr *daddr, int create);
static inline struct inet_peer *inet_getpeer_v4(__be32 v4daddr, int create)
{
@@ -106,11 +106,18 @@ static inline void inet_peer_refcheck(const struct inet_peer *p)
/* can be called with or without local BH being disabled */
-static inline __u16 inet_getid(struct inet_peer *p, int more)
+static inline int inet_getid(struct inet_peer *p, int more)
{
+ int old, new;
more++;
inet_peer_refcheck(p);
- return atomic_add_return(more, &p->ip_id_count) - more;
+ 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;
}
#endif /* _NET_INETPEER_H */

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