tree 425f361f7dab371971766f65fffc28189db11985
parent f699594d436960160f6d5ba84ed4a222f20d11cd
author Eric Biggers <ebiggers@google.com> 1555623867 -0700
committer Herbert Xu <herbert@gondor.apana.org.au> 1555653193 +0800

crypto: ccm - fix incompatibility between "ccm" and "ccm_base"

CCM instances can be created by either the "ccm" template, which only
allows choosing the block cipher, e.g. "ccm(aes)"; or by "ccm_base",
which allows choosing the ctr and cbcmac implementations, e.g.
"ccm_base(ctr(aes-generic),cbcmac(aes-generic))".

However, a "ccm_base" instance prevents a "ccm" instance from being
registered using the same implementations.  Nor will the instance be
found by lookups of "ccm".  This can be used as a denial of service.
Moreover, "ccm_base" instances are never tested by the crypto
self-tests, even if there are compatible "ccm" tests.

The root cause of these problems is that instances of the two templates
use different cra_names.  Therefore, fix these problems by making
"ccm_base" instances set the same cra_name as "ccm" instances, e.g.
"ccm(aes)" instead of "ccm_base(ctr(aes-generic),cbcmac(aes-generic))".

This requires extracting the block cipher name from the name of the ctr
and cbcmac algorithms.  It also requires starting to verify that the
algorithms are really ctr and cbcmac using the same block cipher, not
something else entirely.  But it would be bizarre if anyone were
actually using non-ccm-compatible algorithms with ccm_base, so this
shouldn't break anyone in practice.

Fixes: 4a49b499dfa0 ("[CRYPTO] ccm: Added CCM mode")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>