crypto: ccm - fix incompatibility between "ccm" and "ccm_base"
authorEric Biggers <ebiggers@google.com>
Thu, 18 Apr 2019 21:44:27 +0000 (14:44 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 22 May 2019 05:38:55 +0000 (07:38 +0200)
commitf7fea7c067fb7ecf8337de1c3c760b4ae34ecf90
treee4f90ce9bf698cd2a687d87107389845534b7c49
parent638fffb11c93d12a91650aeb536a4a344a163ee2
crypto: ccm - fix incompatibility between "ccm" and "ccm_base"

commit 6a1faa4a43f5fabf9cbeaa742d916e7b5e73120f upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
crypto/ccm.c