diff options
| author | Eric Dumazet <edumazet@google.com> | 2019-10-22 07:57:46 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-10-23 20:13:22 -0700 |
| commit | 55667441c84fa5e0911a0aac44fb059c15ba6da2 (patch) | |
| tree | 83d3fb8a5acbfbb3f9766f30a1e2343f0f19a90b /include/net/fq_impl.h | |
| parent | 6c5d9c2a6bedbb3c3c14253776320c0ee564f064 (diff) | |
| download | linux-55667441c84fa5e0911a0aac44fb059c15ba6da2.tar.bz2 | |
net/flow_dissector: switch to siphash
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 <edumazet@google.com>
Reported-by: Jonathan Berger <jonathann1@walla.com>
Reported-by: Amit Klein <aksecurity@gmail.com>
Reported-by: Benny Pinkas <benny@pinkas.net>
Cc: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/fq_impl.h')
| -rw-r--r-- | include/net/fq_impl.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/net/fq_impl.h b/include/net/fq_impl.h index be40a4b327e3..107c0d700ed6 100644 --- a/include/net/fq_impl.h +++ b/include/net/fq_impl.h @@ -108,7 +108,7 @@ begin: static u32 fq_flow_idx(struct fq *fq, struct sk_buff *skb) { - u32 hash = skb_get_hash_perturb(skb, fq->perturbation); + u32 hash = skb_get_hash_perturb(skb, &fq->perturbation); return reciprocal_scale(hash, fq->flows_cnt); } @@ -308,7 +308,7 @@ static int fq_init(struct fq *fq, int flows_cnt) INIT_LIST_HEAD(&fq->backlogs); spin_lock_init(&fq->lock); fq->flows_cnt = max_t(u32, flows_cnt, 1); - fq->perturbation = prandom_u32(); + get_random_bytes(&fq->perturbation, sizeof(fq->perturbation)); fq->quantum = 300; fq->limit = 8192; fq->memory_limit = 16 << 20; /* 16 MBytes */ |