From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Herbert Xu , Daniel Borkmann , Thomas Graf , Hannes Frederic Sowa , "David S. Miller" Subject: [PATCH 3.17 42/47] netlink: use jhash as hashfn for rhashtable Date: Sun, 14 Dec 2014 12:21:17 -0800 Message-Id: <20141214201820.176666183@linuxfoundation.org> In-Reply-To: <20141214201818.552715149@linuxfoundation.org> References: <20141214201818.552715149@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Borkmann [ Upstream commit 7f19fc5e0b617593dcda0d9956adc78b559ef1f5 ] 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: e341694e3eb5 ("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 Signed-off-by: Greg Kroah-Hartman --- net/netlink/af_netlink.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -3130,7 +3130,7 @@ static int __init netlink_proto_init(voi .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,