This is a note to let you know that I've just added the patch titled
netns: provide pure entropy for net_hash_mix()
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
netns-provide-pure-entropy-for-net_hash_mix.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Mon Apr 15 07:47:06 CEST 2019
From: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Wed, 27 Mar 2019 08:21:30 -0700
Subject: netns: provide pure entropy for net_hash_mix()
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ 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@xxxxxxxxxx>
Reported-by: Amit Klein <aksecurity@xxxxxxxxx>
Reported-by: Benny Pinkas <benny@xxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/net/net_namespace.h | 1 +
include/net/netns/hash.h | 15 ++-------------
net/core/net_namespace.c | 1 +
3 files changed, 4 insertions(+), 13 deletions(-)
--- 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 */
--- 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
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -285,6 +285,7 @@ static __net_init int setup_net(struct n
atomic_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);
Patches currently in stable-queue which might be from edumazet@xxxxxxxxxx are
queue-4.14/netns-provide-pure-entropy-for-net_hash_mix.patch
queue-4.14/tcp-ensure-dctcp-reacts-to-losses.patch
