crypto: rng - RNGs must return 0 in success case

Change the RNGs to always return 0 in success case.

This patch ensures that seqiv.c works with RNGs other than krng. seqiv
expects that any return code other than 0 is an error. Without the
patch, rfc4106(gcm(aes)) will not work when using a DRBG or an ANSI
X9.31 RNG.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 6 insertions, 1 deletions

diff --git a/crypto/drbg.c b/crypto/drbg.c
index 56c1d7ec3d9e..b69409cb7e6a 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -1280,7 +1280,7 @@ static void drbg_restore_shadow(struct drbg_state *drbg,
  *        as defined in SP800-90A. The additional input is mixed into
  *        the state in addition to the pulled entropy.
  *
- * return: generated number of bytes
+ * return: 0 when all bytes are generated; < 0 in case of an error
  */
 static int drbg_generate(struct drbg_state *drbg,
                          unsigned char *buf, unsigned int buflen,
@@ -1419,6 +1419,11 @@ static int drbg_generate(struct drbg_state *drbg,
         }
 #endif
 
+        /*
+         * All operations were successful, return 0 as mandated by
+         * the kernel crypto API interface.
+         */
+        len = 0;
 err:
         shadow->d_ops->crypto_fini(shadow);
         drbg_restore_shadow(drbg, &shadow);