[PATCH net-next] IPsec: do not ignore crypto err in ah input

[PATCH net-next] IPsec: do not ignore crypto err in ah input

[Gilad Ben-Yossef]

ah input processing uses the asynchrnous hash crypto API which
supplies an error code as part of the operation completion but 
the error code was being ignored.

Treat a crypto API error indication as a verification failure.

While a crypto API reported error would almost certainly result
in a memcpy of the digest failing anyway and thus the security
risk seems minor, performing a memory compare on what might be
uninitialized memory is wrong.

Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
---

The change was boot tested on Arm64 but I did not exercise
the specific error code path in question.

 net/ipv4/ah4.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/ipv4/ah4.c b/net/ipv4/ah4.c
index f2a7102..22377c8 100644
--- a/net/ipv4/ah4.c
+++ b/net/ipv4/ah4.c
@@ -270,6 +270,9 @@ static void ah_input_done(struct crypto_async_request *base, int err)
 	int ihl = ip_hdrlen(skb);
 	int ah_hlen = (ah->hdrlen + 2) << 2;
 
+	if (err)
+		goto out;
+
 	work_iph = AH_SKB_CB(skb)->tmp;
 	auth_data = ah_tmp_auth(work_iph, ihl);
 	icv = ah_tmp_icv(ahp->ahash, auth_data, ahp->icv_trunc_len);
-- 
2.1.4

Re: [PATCH net-next] IPsec: do not ignore crypto err in ah input

[Alexander Alemayhu]

On Thu, Jan 12, 2017 at 03:33:22PM +0200, Gilad Ben-Yossef wrote:
> ah input processing uses the asynchrnous hash crypto API which
> supplies an error code as part of the operation completion but 
> the error code was being ignored.
>
s/asynchrnous/asynchronous

-- 
Mit freundlichen Grüßen

Alexander Alemayhu

Re: [PATCH net-next] IPsec: do not ignore crypto err in ah input

[Gilad Ben-Yossef]

On Fri, Jan 13, 2017 at 9:45 AM, Alexander Alemayhu
<alexander@alemayhu.com> wrote:
> On Thu, Jan 12, 2017 at 03:33:22PM +0200, Gilad Ben-Yossef wrote:
>> ah input processing uses the asynchrnous hash crypto API which
>> supplies an error code as part of the operation completion but
>> the error code was being ignored.
>>
> s/asynchrnous/asynchronous

Yes, I have missed that.

Thank you for your review. I will send a fixed version.

Thanks,
Gilad

-- 
Gilad Ben-Yossef
Chief Coffee Drinker

"If you take a class in large-scale robotics, can you end up in a
situation where the homework eats your dog?"
 -- Jean-Baptiste Queru