From 355b98553789b646ed97ad801a619ff898471b92 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 27 Mar 2019 08:21:30 -0700 Subject: 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 Reported-by: Amit Klein Reported-by: Benny Pinkas Cc: Pavel Emelyanov Signed-off-by: David S. Miller --- include/net/net_namespace.h | 1 + include/net/netns/hash.h | 10 ++-------- 2 files changed, 3 insertions(+), 8 deletions(-) (limited to 'include') 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 - -struct net; +#include 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 -- cgit v1.2.3