[PATCH v2 net-next] IPsec: do not ignore crypto err in ah input

[PATCH v2 net-next] IPsec: do not ignore crypto err in ah input

[Gilad Ben-Yossef]

ah input processing uses the asynchronous 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 
memcmp 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>
CC: Alexander Alemayhu <alexander@alemayhu.com>
---

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

Changes from v1:
- Fixed typo in patch description pointed out by Alexander

 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 v2 net-next] IPsec: do not ignore crypto err in ah input

[Steffen Klassert]

On Sun, Jan 15, 2017 at 08:09:43AM +0200, Gilad Ben-Yossef wrote:
> ah input processing uses the asynchronous 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 
> memcmp 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>
> CC: Alexander Alemayhu <alexander@alemayhu.com>
> ---
> 
> The change was boot tested on Arm64 but I did not exercise
> the specific error code path in question.
> 
> Changes from v1:
> - Fixed typo in patch description pointed out by Alexander
> 
>  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;
> +

IPv6 has the same problem, can we get it fixed there too?

Thanks!