diff options
| author | Eric Dumazet <edumazet@google.com> | 2019-10-22 07:57:46 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-11-10 11:25:37 +0100 |
| commit | a9de6f42e945cdb24b59c7ab7ebad1eba6cb5875 (patch) | |
| tree | a029bdb9d56c42db6072c601db01669650a38f32 /include/net | |
| parent | 4fa6002a34db62f5a5d536f30fc9dedd1ce7ee84 (diff) | |
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 <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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/net')
| -rw-r--r-- | include/net/flow_dissector.h | 3 | ||||
| -rw-r--r-- | include/net/fq.h | 2 | ||||
| -rw-r--r-- | include/net/fq_impl.h | 4 |
3 files changed, 5 insertions, 4 deletions
diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h index 22aba321282d..227dc0a84172 100644 --- a/include/net/flow_dissector.h +++ b/include/net/flow_dissector.h @@ -4,6 +4,7 @@ #include <linux/types.h> #include <linux/in6.h> +#include <linux/siphash.h> #include <uapi/linux/if_ether.h> /** @@ -229,7 +230,7 @@ struct flow_dissector { struct flow_keys { struct flow_dissector_key_control control; #define FLOW_KEYS_HASH_START_FIELD basic - struct flow_dissector_key_basic basic; + struct flow_dissector_key_basic basic __aligned(SIPHASH_ALIGNMENT); struct flow_dissector_key_tags tags; struct flow_dissector_key_vlan vlan; struct flow_dissector_key_keyid keyid; 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; diff --git a/include/net/fq_impl.h b/include/net/fq_impl.h index ac1a2317941e..46903e23eab9 100644 --- a/include/net/fq_impl.h +++ b/include/net/fq_impl.h @@ -105,7 +105,7 @@ static struct fq_flow *fq_flow_classify(struct fq *fq, lockdep_assert_held(&fq->lock); - hash = skb_get_hash_perturb(skb, fq->perturbation); + hash = skb_get_hash_perturb(skb, &fq->perturbation); idx = reciprocal_scale(hash, fq->flows_cnt); flow = &fq->flows[idx]; @@ -255,7 +255,7 @@ 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 */ |