From 252bdb3b0ba5e0b08da40b4a8ef0567d4cef70ff Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Wed, 10 Dec 2014 16:33:10 +0100 Subject: [PATCH] netlink: use jhash as hashfn for rhashtable For netlink, we shouldn't be using arch_fast_hash() as a hashing discipline, but rather jhash() instead. Since netlink sockets can be opened by any user, a local attacker would be able to easily create collisions with the DPDK-derived arch_fast_hash(), which trades off performance for security by using crc32 CPU instructions on x86_64. While it might have a legimite use case in other places, it should be avoided in netlink context, though. As rhashtable's API is very flexible, we could later on still decide on other hashing disciplines, if legitimate. Reference: http://thread.gmane.org/gmane.linux.kernel/1844123 Fixes: 5f18ca185e81 ("netlink: Convert netlink_lookup() to use RCU protected hash table") Cc: Herbert Xu Signed-off-by: Daniel Borkmann Acked-by: Thomas Graf Acked-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- net/netlink/af_netlink.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index cc9bcf008b033..ef5f77b44ec72 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -3129,7 +3129,7 @@ static int __init netlink_proto_init(void) .head_offset = offsetof(struct netlink_sock, node), .key_offset = offsetof(struct netlink_sock, portid), .key_len = sizeof(u32), /* portid */ - .hashfn = arch_fast_hash, + .hashfn = jhash, .max_shift = 16, /* 64K */ .grow_decision = rht_grow_above_75, .shrink_decision = rht_shrink_below_30, -- 2.39.5