diff options
| author | Eric Dumazet | 2019-03-27 08:21:30 -0700 |
|---|---|---|
| committer | David S. Miller | 2019-03-28 17:00:45 -0700 |
| commit | 355b98553789b646ed97ad801a619ff898471b92 (patch) | |
| tree | 433cd3a5856dfdcc1022cb5cc2e7c1aa0bf383e3 | |
| parent | 6289d0facd9ebce4cc83e5da39e15643ee998dc5 (diff) | |
netns: provide pure entropy for net_hash_mix()
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>
| -rw-r--r-- | include/net/net_namespace.h | 1 | ||||
| -rw-r--r-- | include/net/netns/hash.h | 10 | ||||
| -rw-r--r-- | net/core/net_namespace.c | 1 |
3 files changed, 4 insertions, 8 deletions
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index a68ced28d8f4..12689ddfc24c 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -59,6 +59,7 @@ 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 16a842456189..d9b665151f3d 100644 --- a/include/net/netns/hash.h +++ b/include/net/netns/hash.h @@ -2,16 +2,10 @@ #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 - return (u32)(((unsigned long)net) >> ilog2(sizeof(*net))); -#else - return 0; -#endif + return net->hash_mix; } #endif diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index 17f36317363d..7e6dcc625701 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -304,6 +304,7 @@ static __net_init int setup_net(struct net *net, struct user_namespace *user_ns) refcount_set(&net->count, 1); refcount_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); |