diff options
| author | Eric Dumazet <edumazet@google.com> | 2019-03-27 08:21:30 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-04-27 09:33:55 +0200 |
| commit | 0ede14314f6d9e6a172eb4c4b6b9fe5477aa70bc (patch) | |
| tree | c54220a3d0626daf923f1187f8965a06a9ea7c34 | |
| parent | 68337354043a3d5207cd4f055e5a8342ec4eec0f (diff) | |
netns: provide pure entropy for net_hash_mix()
[ Upstream commit 355b98553789b646ed97ad801a619ff898471b92 ]
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | include/net/net_namespace.h | 1 | ||||
| -rw-r--r-- | include/net/netns/hash.h | 15 | ||||
| -rw-r--r-- | net/core/net_namespace.c | 1 |
3 files changed, 4 insertions, 13 deletions
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index 6965dfe7e88b..0daed810724d 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -53,6 +53,7 @@ struct net { */ spinlock_t rules_mod_lock; + u32 hash_mix; atomic64_t cookie_gen; struct list_head list; /* list of network namespaces */ diff --git a/include/net/netns/hash.h b/include/net/netns/hash.h index 69a6715d9f3f..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> - -struct net; +#include <net/net_namespace.h> 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 (u32)(((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 ccd20669ac00..087ce1598b74 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -280,6 +280,7 @@ 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; idr_init(&net->netns_ids); |