On Thu, Apr 18, 2019 at 02:43:02PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@xxxxxxxxxx>
>
> GCM instances can be created by either the "gcm" template, which only
> allows choosing the block cipher, e.g. "gcm(aes)"; or by "gcm_base",
> which allows choosing the ctr and ghash implementations, e.g.
> "gcm_base(ctr(aes-generic),ghash-generic)".
>
> However, a "gcm_base" instance prevents a "gcm" instance from being
> registered using the same implementations. Nor will the instance be
> found by lookups of "gcm". This can be used as a denial of service.
> Moreover, "gcm_base" instances are never tested by the crypto
> self-tests, even if there are compatible "gcm" tests.
>
> The root cause of these problems is that instances of the two templates
> use different cra_names. Therefore, fix these problems by making
> "gcm_base" instances set the same cra_name as "gcm" instances, e.g.
> "gcm(aes)" instead of "gcm_base(ctr(aes-generic),ghash-generic)".
>
> This requires extracting the block cipher name from the name of the ctr
> algorithm. It also requires starting to verify that the algorithms are
> really ctr and ghash, not something else entirely. But it would be
> bizarre if anyone were actually using non-gcm-compatible algorithms with
> gcm_base, so this shouldn't break anyone in practice.
>
> Fixes: d00aa19b507b ("[CRYPTO] gcm: Allow block cipher parameter")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> ---
>
> Changed since v2:
> - Leave checks for ctr cra_blocksize == 1 and ghash digestsize == 16.
>
> Changed since v1:
> - Verify that ghash is really ghash (based on name).
> - Improved commit message.
>
> crypto/gcm.c | 34 +++++++++++-----------------------
> 1 file changed, 11 insertions(+), 23 deletions(-)
Patch applied. Thanks.
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
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