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

Message ID 20211130141009.6791-2-nstange@suse.de
State Accepted
Commit 8f7977284331d0b0f210efa98a5d3fdcb2a65dd3
Headers show
Series crypto: jitterentropy - bound collection loop | expand

Commit Message

Nicolai Stange Nov. 30, 2021, 2:10 p.m. UTC
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(-)

Comments

Stephan Mueller Nov. 30, 2021, 6:04 p.m. UTC | #1
Am Dienstag, 30. November 2021, 15:10:07 CET schrieb Nicolai Stange:

Hi Nicolai,

> 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>

Reviewed-by: Stephan Mueller <smueller@chronox.de>

Thanks
Stephan
> ---
>  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);
> 
>  				/*


Ciao
Stephan
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Patch

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);
 
 				/*