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authorEric Dumazet <edumazet@google.com>2019-03-27 08:21:30 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-04-17 08:37:50 +0200
commitadbb8bdd392db14dc80ad1ac29f8f1d37ab57a62 (patch)
tree3a97be430b3d390b97e8ec73eb1219e99d19c3c4 /include
parent0349ad0656a3ea2e6ecb55da946a7000f6abdba5 (diff)
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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>
Diffstat (limited to 'include')
-rw-r--r--include/net/net_namespace.h1
-rw-r--r--include/net/netns/hash.h15
2 files changed, 3 insertions, 13 deletions
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index f4bf75fac349..d96c9d9cca96 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -56,6 +56,7 @@ 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 24c78183a4c2..d9b665151f3d 100644
--- a/include/net/netns/hash.h
+++ b/include/net/netns/hash.h
@@ -2,21 +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
- /*
- * 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