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| author | Eric Dumazet <edumazet@google.com> | 2019-03-27 08:21:30 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-04-27 09:30:26 +0200 |
| commit | c2bca92ba948f3def1f99f6b429ec39e07354dc2 (patch) | |
| tree | 9c0208c8c1915cc421d6fd627df2d4712275b3fa | |
| parent | 01418a991494514347949baf6655ce147c566c95 (diff) | |
| download | linux-stable-c2bca92ba948f3def1f99f6b429ec39e07354dc2.tar.gz linux-stable-c2bca92ba948f3def1f99f6b429ec39e07354dc2.tar.bz2 linux-stable-c2bca92ba948f3def1f99f6b429ec39e07354dc2.zip | |
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 | 2 | ||||
| -rw-r--r-- | include/net/netns/hash.h | 15 | ||||
| -rw-r--r-- | net/core/net_namespace.c | 1 |
3 files changed, 5 insertions, 13 deletions
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index 7c9518bf0453..209d33a0f752 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..31441b7f5799 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 unsigned int net_hash_mix(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 a81693f9753c..3f55c2bcadad 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; |