crypto: des3_ede - permit weak keys unless REQ_WEAK_KEY set

While its a slightly insane to bypass the key1 == key2 ||
key2 == key3 check in triple-des, since it reduces it to the
same strength as des, some folks do need to do this from time
to time for backwards compatibility with des.

My own case is FIPS CAVS test vectors. Many triple-des test
vectors use a single key, replicated 3x. In order to get the
expected results, des3_ede_setkey() needs to only reject weak
keys if the CRYPTO_TFM_REQ_WEAK_KEY flag is set.

Also sets a more appropriate RES flag when a weak key is found.

Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/des_generic.c b/crypto/des_generic.c
index 5d0e4580f998c23650eb24ba73135cd5af68a01e..5bd3ee345a64d8e60604a32097818a3a3d369a46 100644 (file)
--- a/crypto/des_generic.c
+++ b/crypto/des_generic.c
@@ -868,9 +868,10 @@ static int des3_ede_setkey(struct crypto_tfm *tfm, const u8 *key,
        u32 *flags = &tfm->crt_flags;
 
        if (unlikely(!((K[0] ^ K[2]) | (K[1] ^ K[3])) ||
-                    !((K[2] ^ K[4]) | (K[3] ^ K[5]))))
+                    !((K[2] ^ K[4]) | (K[3] ^ K[5]))) &&
+                    (*flags & CRYPTO_TFM_REQ_WEAK_KEY))
        {
-               *flags |= CRYPTO_TFM_RES_BAD_KEY_SCHED;
+               *flags |= CRYPTO_TFM_RES_WEAK_KEY;
                return -EINVAL;
        }