[PATCH 1/3] crypto: drbg - ignore jitterentropy errors if not in FIPS mode

Nicolai Stange
2021-11-30T14:10:40Z

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: Nicolai Stange <nstange@suse.de>
---
crypto/drbg.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/crypto/drbg.c b/crypto/drbg.c
index 5977a72afb03..177983b6ae38 100644
--- a/crypto/drbg.c
+++ b/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);

/*
--
2.26.2