Hi Greg,
On 29.10.2021 10:39, Greg KH wrote:
[Please note: This e-mail is from an EXTERNAL e-mail address]
On Thu, Oct 28, 2021 at 10:08:58PM +0300, Ovidiu Panait wrote:
The following commits are needed to fix CVE-2021-20322:
ipv4:
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6457378fe796815c973f631a1904e147d6ee33b1
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=67d6d681e15b578c1725bad8ad079e05d1c48a8e
ipv6:
[3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4785305c05b25a242e5314cc821f54ade4c18810
[4] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a00df2caffed3883c341d5685f830434312e4a43
Commit [2] is already present in 4.19 stable, so backport the
remaining three fixes with minor context adjustments.
Eric Dumazet (3):
ipv4: use siphash instead of Jenkins in fnhe_hashfun()
ipv6: use siphash in rt6_exception_hash()
ipv6: make exception cache less predictible
net/ipv4/route.c | 12 ++++++------
net/ipv6/route.c | 25 ++++++++++++++++++-------
2 files changed, 24 insertions(+), 13 deletions(-)
--
2.25.1
You sent 0/3 but only 2 patches showed up?
Can you please resend all 3?
I tried resending the full patchset, but the last patch is still not
showing up.
git send-email doesn't report any errors:
OK. Log says:
MAIL FROM:<ovidiu.panait@xxxxxxxxxxxxx>
RCPT TO:<stable@xxxxxxxxxxxxxxx>
RCPT TO:<gregkh@xxxxxxxxxxxxxxxxxxx>
From: Ovidiu Panait <ovidiu.panait@xxxxxxxxxxxxx>
To: stable@xxxxxxxxxxxxxxx
Cc: gregkh@xxxxxxxxxxxxxxxxxxx
Subject: [PATCH 4.19 3/3] ipv6: make exception cache less predictible
Date: Fri, 29 Oct 2021 10:50:27 +0300
Message-Id: <20211029075027.1910142-4-ovidiu.panait@xxxxxxxxxxxxx>
X-Mailer: git-send-email 2.25.1
In-Reply-To: <20211029075027.1910142-1-ovidiu.panait@xxxxxxxxxxxxx>
References: <20211029075027.1910142-1-ovidiu.panait@xxxxxxxxxxxxx>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Result: 250
I have attached the 4.19 backport of a00df2caffed ("ipv6: make exception
cache less predictible").
Ovidiu
thanks,
greg k-h
>From c9f6f8ebbc70e5cf357f80b77400f0233027b39d Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Sun, 29 Aug 2021 15:16:14 -0700
Subject: [PATCH 4.19 3/3] ipv6: make exception cache less predictible
commit a00df2caffed3883c341d5685f830434312e4a43 upstream.
Even after commit 4785305c05b2 ("ipv6: use siphash in rt6_exception_hash()"),
an attacker can still use brute force to learn some secrets from a victim
linux host.
One way to defeat these attacks is to make the max depth of the hash
table bucket a random value.
Before this patch, each bucket of the hash table used to store exceptions
could contain 6 items under attack.
After the patch, each bucket would contains a random number of items,
between 6 and 10. The attacker can no longer infer secrets.
This is slightly increasing memory size used by the hash table,
we do not expect this to be a problem.
Following patch is dealing with the same issue in IPv4.
Fixes: 35732d01fe31 ("ipv6: introduce a hash table to store dst cache")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reported-by: Keyu Man <kman001@xxxxxxx>
Cc: Wei Wang <weiwan@xxxxxxxxxx>
Cc: Martin KaFai Lau <kafai@xxxxxx>
Reviewed-by: David Ahern <dsahern@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[OP: adjusted context for 4.19 stable]
Signed-off-by: Ovidiu Panait <ovidiu.panait@xxxxxxxxxxxxx>
---
net/ipv6/route.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 9bc806a4ded6..d04f3951c5fb 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1454,6 +1454,7 @@ static int rt6_insert_exception(struct rt6_info *nrt,
struct rt6_exception_bucket *bucket;
struct in6_addr *src_key = NULL;
struct rt6_exception *rt6_ex;
+ int max_depth;
int err = 0;
spin_lock_bh(&rt6_exception_lock);
@@ -1515,7 +1516,9 @@ static int rt6_insert_exception(struct rt6_info *nrt,
bucket->depth++;
net->ipv6.rt6_stats->fib_rt_cache++;
- if (bucket->depth > FIB6_MAX_DEPTH)
+ /* Randomize max depth to avoid some side channels attacks. */
+ max_depth = FIB6_MAX_DEPTH + prandom_u32_max(FIB6_MAX_DEPTH);
+ while (bucket->depth > max_depth)
rt6_exception_remove_oldest(bucket);
out:
--
2.25.1
