crypto: drbg - ignore jitterentropy errors if not in FIPS mode

A subsequent patch will make the jitterentropy RNG to unconditionally
report health test errors back to callers, independent of whether
fips_enabled is set or not. The DRBG needs access to a functional
jitterentropy instance only in FIPS mode (because it's the only SP800-90B
compliant entropy source as it currently stands). Thus, it is perfectly
fine for the DRBGs to obtain entropy from the jitterentropy source only
on a best effort basis if fips_enabled is off.

Make the DRBGs to ignore jitterentropy failures if fips_enabled is not set.
Signed-off-by: NNicolai Stange <nstange@suse.de>
Reviewed-by: NStephan Mueller <smueller@chronox.de>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

crypto/drbg.c

@@ -1193,11 +1193,14 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
 			pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
 				 entropylen);
 		} else {
-			/* Get seed from Jitter RNG */
+			/*
+			 * Get seed from Jitter RNG, failures are
+			 * fatal only in FIPS mode.
+			 */
 			ret = crypto_rng_get_bytes(drbg->jent,
 						   entropy + entropylen,
 						   entropylen);
-			if (ret) {
+			if (fips_enabled && ret) {
 				pr_devel("DRBG: jent failed with %d\n", ret);
 
 				/*