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| author | Eric Dumazet <edumazet@google.com> | 2019-03-27 08:21:30 -0700 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2019-07-09 22:04:22 +0100 |
| commit | 188da790e1f4d164bcfdea486e91fd47e1ba59c5 (patch) | |
| tree | 4ce30ff09f637f1bf7151d5095cf3e5a4192d44a | |
| parent | a62393d7eb63bd075c51154002825cc7ab4dd3eb (diff) | |
| download | linux-stable-188da790e1f4d164bcfdea486e91fd47e1ba59c5.tar.gz linux-stable-188da790e1f4d164bcfdea486e91fd47e1ba59c5.tar.bz2 linux-stable-188da790e1f4d164bcfdea486e91fd47e1ba59c5.zip | |
netns: provide pure entropy for net_hash_mix()
commit 355b98553789b646ed97ad801a619ff898471b92 upstream.
net_hash_mix() currently uses kernel address of a struct net,
and is used in many places that could be used to reveal this
address to a patient attacker, thus defeating KASLR, for
the typical case (initial net namespace, &init_net is
not dynamically allocated)
I believe the original implementation tried to avoid spending
too many cycles in this function, but security comes first.
Also provide entropy regardless of CONFIG_NET_NS.
Fixes: 0b4419162aa6 ("netns: introduce the net_hash_mix "salt" for hashes")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Amit Klein <aksecurity@gmail.com>
Reported-by: Benny Pinkas <benny@pinkas.net>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | include/net/net_namespace.h | 2 | ||||
| -rw-r--r-- | include/net/netns/hash.h | 17 | ||||
| -rw-r--r-- | net/core/net_namespace.c | 1 |
3 files changed, 6 insertions, 14 deletions
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index f772dab65474..b3358ba51504 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -54,6 +54,8 @@ struct net { #endif spinlock_t rules_mod_lock; + u32 hash_mix; + struct list_head list; /* list of network namespaces */ struct list_head cleanup_list; /* namespaces on death row */ struct list_head exit_list; /* Use only net_mutex */ diff --git a/include/net/netns/hash.h b/include/net/netns/hash.h index c06ac58ca107..a347b2f9e748 100644 --- a/include/net/netns/hash.h +++ b/include/net/netns/hash.h @@ -1,21 +1,10 @@ #ifndef __NET_NS_HASH_H__ #define __NET_NS_HASH_H__ -#include <asm/cache.h> +#include <net/net_namespace.h> -struct net; - -static inline unsigned int net_hash_mix(struct net *net) +static inline u32 net_hash_mix(const struct net *net) { -#ifdef CONFIG_NET_NS - /* - * shift this right to eliminate bits, that are - * always zeroed - */ - - return (unsigned)(((unsigned long)net) >> L1_CACHE_SHIFT); -#else - return 0; -#endif + return net->hash_mix; } #endif diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index 85b62691f4f2..45ebcc039a68 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -156,6 +156,7 @@ static __net_init int setup_net(struct net *net, struct user_namespace *user_ns) atomic_set(&net->count, 1); atomic_set(&net->passive, 1); + get_random_bytes(&net->hash_mix, sizeof(u32)); net->dev_base_seq = 1; net->user_ns = user_ns; |