From 1f94465d13ace2d4610c4eb2b362454ce2a9d87c Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 22 Oct 2019 07:57:46 -0700 Subject: net/flow_dissector: switch to siphash commit 55667441c84fa5e0911a0aac44fb059c15ba6da2 upstream. UDP IPv6 packets auto flowlabels are using a 32bit secret (static u32 hashrnd in net/core/flow_dissector.c) and apply jhash() over fields known by the receivers. Attackers can easily infer the 32bit secret and use this information to identify a device and/or user, since this 32bit secret is only set at boot time. Really, using jhash() to generate cookies sent on the wire is a serious security concern. Trying to change the rol32(hash, 16) in ip6_make_flowlabel() would be a dead end. Trying to periodically change the secret (like in sch_sfq.c) could change paths taken in the network for long lived flows. Let's switch to siphash, as we did in commit df453700e8d8 ("inet: switch IP ID generator to siphash") Using a cryptographically strong pseudo random function will solve this privacy issue and more generally remove other weak points in the stack. Packet schedulers using skb_get_hash_perturb() benefit from this change. Fixes: b56774163f99 ("ipv6: Enable auto flow labels by default") Fixes: 42240901f7c4 ("ipv6: Implement different admin modes for automatic flow labels") Fixes: 67800f9b1f4e ("ipv6: Call skb_get_hash_flowi6 to get skb->hash in ip6_make_flowlabel") Fixes: cb1ce2ef387b ("ipv6: Implement automatic flow label generation on transmit") Signed-off-by: Eric Dumazet Reported-by: Jonathan Berger Reported-by: Amit Klein Reported-by: Benny Pinkas Cc: Tom Herbert Signed-off-by: David S. Miller Signed-off-by: Mahesh Bandewar Signed-off-by: Greg Kroah-Hartman --- include/net/fq.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/net/fq.h') diff --git a/include/net/fq.h b/include/net/fq.h index 6d8521a30c5c..2c7687902789 100644 --- a/include/net/fq.h +++ b/include/net/fq.h @@ -70,7 +70,7 @@ struct fq { struct list_head backlogs; spinlock_t lock; u32 flows_cnt; - u32 perturbation; + siphash_key_t perturbation; u32 limit; u32 memory_limit; u32 memory_usage; -- cgit v1.2.3