• Eric Biggers's avatar
    crypto: gcm - fix incompatibility between "gcm" and "gcm_base" · b5344a0e
    Eric Biggers authored
    commit f699594d436960160f6d5ba84ed4a222f20d11cd upstream.
    
    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: d00aa19b ("[CRYPTO] gcm: Allow block cipher parameter")
    Cc: stable@vger.kernel.org
    Signed-off-by: 's avatarEric Biggers <ebiggers@google.com>
    Signed-off-by: 's avatarHerbert Xu <herbert@gondor.apana.org.au>
    Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    b5344a0e