* [PATCH] crypto: ccp/gcm - use const time tag comparison.
@ 2019-07-02 0:01 Cfir Cohen
2019-07-02 0:25 ` Eric Biggers
0 siblings, 1 reply; 4+ messages in thread
From: Cfir Cohen @ 2019-07-02 0:01 UTC (permalink / raw)
To: Tom Lendacky, Gary Hook, Herbert Xu, David Rientjes
Cc: linux-kernel, linux-crypto, Cfir Cohen
Avoid leaking GCM tag through timing side channel.
Signed-off-by: Cfir Cohen <cfir@google.com>
---
drivers/crypto/ccp/ccp-ops.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/crypto/ccp/ccp-ops.c b/drivers/crypto/ccp/ccp-ops.c
index db8de89d990f..633670220f6c 100644
--- a/drivers/crypto/ccp/ccp-ops.c
+++ b/drivers/crypto/ccp/ccp-ops.c
@@ -840,7 +840,8 @@ static int ccp_run_aes_gcm_cmd(struct ccp_cmd_queue *cmd_q,
if (ret)
goto e_tag;
- ret = memcmp(tag.address, final_wa.address, AES_BLOCK_SIZE);
+ ret = crypto_memneq(tag.address, final_wa.address,
+ AES_BLOCK_SIZE) ? -EBADMSG : 0;
ccp_dm_free(&tag);
}
--
2.22.0.410.gd8fdbe21b5-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] crypto: ccp/gcm - use const time tag comparison.
2019-07-02 0:01 [PATCH] crypto: ccp/gcm - use const time tag comparison Cfir Cohen
@ 2019-07-02 0:25 ` Eric Biggers
2019-07-02 15:41 ` Gary R Hook
0 siblings, 1 reply; 4+ messages in thread
From: Eric Biggers @ 2019-07-02 0:25 UTC (permalink / raw)
To: Cfir Cohen
Cc: Tom Lendacky, Gary Hook, Herbert Xu, David Rientjes, linux-kernel,
linux-crypto
On Mon, Jul 01, 2019 at 05:01:32PM -0700, Cfir Cohen wrote:
> Avoid leaking GCM tag through timing side channel.
>
> Signed-off-by: Cfir Cohen <cfir@google.com>
> ---
> drivers/crypto/ccp/ccp-ops.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/crypto/ccp/ccp-ops.c b/drivers/crypto/ccp/ccp-ops.c
> index db8de89d990f..633670220f6c 100644
> --- a/drivers/crypto/ccp/ccp-ops.c
> +++ b/drivers/crypto/ccp/ccp-ops.c
> @@ -840,7 +840,8 @@ static int ccp_run_aes_gcm_cmd(struct ccp_cmd_queue *cmd_q,
> if (ret)
> goto e_tag;
>
> - ret = memcmp(tag.address, final_wa.address, AES_BLOCK_SIZE);
> + ret = crypto_memneq(tag.address, final_wa.address,
> + AES_BLOCK_SIZE) ? -EBADMSG : 0;
> ccp_dm_free(&tag);
> }
>
> --
> 2.22.0.410.gd8fdbe21b5-goog
>
Looks like this needs:
Fixes: 36cf515b9bbe ("crypto: ccp - Enable support for AES GCM on v5 CCPs")
Cc: <stable@vger.kernel.org> # v4.12+
- Eric
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] crypto: ccp/gcm - use const time tag comparison.
2019-07-02 0:25 ` Eric Biggers
@ 2019-07-02 15:41 ` Gary R Hook
2019-07-02 15:53 ` Eric Biggers
0 siblings, 1 reply; 4+ messages in thread
From: Gary R Hook @ 2019-07-02 15:41 UTC (permalink / raw)
To: Eric Biggers, Cfir Cohen
Cc: Lendacky, Thomas, Hook, Gary, Herbert Xu, David Rientjes,
linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org
On 7/1/19 7:25 PM, Eric Biggers wrote:
> On Mon, Jul 01, 2019 at 05:01:32PM -0700, Cfir Cohen wrote:
>> Avoid leaking GCM tag through timing side channel.
>>
>> Signed-off-by: Cfir Cohen <cfir@google.com>
>> ---
>> drivers/crypto/ccp/ccp-ops.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/crypto/ccp/ccp-ops.c b/drivers/crypto/ccp/ccp-ops.c
>> index db8de89d990f..633670220f6c 100644
>> --- a/drivers/crypto/ccp/ccp-ops.c
>> +++ b/drivers/crypto/ccp/ccp-ops.c
>> @@ -840,7 +840,8 @@ static int ccp_run_aes_gcm_cmd(struct ccp_cmd_queue *cmd_q,
>> if (ret)
>> goto e_tag;
>>
>> - ret = memcmp(tag.address, final_wa.address, AES_BLOCK_SIZE);
>> + ret = crypto_memneq(tag.address, final_wa.address,
>> + AES_BLOCK_SIZE) ? -EBADMSG : 0;
>> ccp_dm_free(&tag);
>> }
>>
>> --
>> 2.22.0.410.gd8fdbe21b5-goog
>>
>
> Looks like this needs:
>
> Fixes: 36cf515b9bbe ("crypto: ccp - Enable support for AES GCM on v5 CCPs")
> Cc: <stable@vger.kernel.org> # v4.12+
Yes, it does. For clarity, does that mean you've taken care of this?
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] crypto: ccp/gcm - use const time tag comparison.
2019-07-02 15:41 ` Gary R Hook
@ 2019-07-02 15:53 ` Eric Biggers
0 siblings, 0 replies; 4+ messages in thread
From: Eric Biggers @ 2019-07-02 15:53 UTC (permalink / raw)
To: Gary R Hook
Cc: Cfir Cohen, Lendacky, Thomas, Hook, Gary, Herbert Xu,
David Rientjes, linux-kernel@vger.kernel.org,
linux-crypto@vger.kernel.org
On Tue, Jul 02, 2019 at 03:41:23PM +0000, Gary R Hook wrote:
> On 7/1/19 7:25 PM, Eric Biggers wrote:
> > On Mon, Jul 01, 2019 at 05:01:32PM -0700, Cfir Cohen wrote:
> >> Avoid leaking GCM tag through timing side channel.
> >>
> >> Signed-off-by: Cfir Cohen <cfir@google.com>
> >> ---
> >> drivers/crypto/ccp/ccp-ops.c | 3 ++-
> >> 1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/crypto/ccp/ccp-ops.c b/drivers/crypto/ccp/ccp-ops.c
> >> index db8de89d990f..633670220f6c 100644
> >> --- a/drivers/crypto/ccp/ccp-ops.c
> >> +++ b/drivers/crypto/ccp/ccp-ops.c
> >> @@ -840,7 +840,8 @@ static int ccp_run_aes_gcm_cmd(struct ccp_cmd_queue *cmd_q,
> >> if (ret)
> >> goto e_tag;
> >>
> >> - ret = memcmp(tag.address, final_wa.address, AES_BLOCK_SIZE);
> >> + ret = crypto_memneq(tag.address, final_wa.address,
> >> + AES_BLOCK_SIZE) ? -EBADMSG : 0;
> >> ccp_dm_free(&tag);
> >> }
> >>
> >> --
> >> 2.22.0.410.gd8fdbe21b5-goog
> >>
> >
> > Looks like this needs:
> >
> > Fixes: 36cf515b9bbe ("crypto: ccp - Enable support for AES GCM on v5 CCPs")
> > Cc: <stable@vger.kernel.org> # v4.12+
>
>
> Yes, it does. For clarity, does that mean you've taken care of this?
>
Herbert is the person who will apply this, so he'd need to do it. But it might
be better just to resend.
- Eric
^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-07-02 0:01 [PATCH] crypto: ccp/gcm - use const time tag comparison Cfir Cohen
2019-07-02 0:25 ` Eric Biggers
2019-07-02 15:41 ` Gary R Hook
2019-07-02 15:53 ` Eric Biggers
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