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From:   Dimitri John Ledkov <dimitri.ledkov@canonical.com>
To:     Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>
Cc:     smueller@chronox.de, linux-crypto@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH v2 3/4] crypto: drbg - ensure drbg hmac sha512 is used in FIPS selftests
Date:   Mon, 30 Oct 2023 14:05:15 +0200
Message-Id: <20231030120517.39424-4-dimitri.ledkov@canonical.com>
In-Reply-To: <20231030120517.39424-1-dimitri.ledkov@canonical.com>
References: <20231029204823.663930-1-dimitri.ledkov@canonical.com>
 <20231030120517.39424-1-dimitri.ledkov@canonical.com>
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Update code comment, self test & healthcheck to use HMAC SHA512,
instead of HMAC SHA256. These changes are in dead-code, or FIPS
enabled code-paths only and have not effect on usual kernel builds.

On systems booting in FIPS mode that has the effect of switch sanity
selftest to HMAC sha512 based (which has been the default DRBG).

This patch updates code from 9b7b94683a ("crypto: DRBG - switch to
HMAC SHA512 DRBG as default DRBG"), but is not interesting to
cherry-pick for stable updates, because it doesn't affect regular
builds, nor has any tangible effect on FIPS certifcation.

Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Reviewed-by: Stephan Mueller <smueller@chronox.de>
---
 crypto/drbg.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/crypto/drbg.c b/crypto/drbg.c
index b120e2866b..99666193d9 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -111,9 +111,9 @@
  * as stdrng. Each DRBG receives an increasing cra_priority values the later
  * they are defined in this array (see drbg_fill_array).
  *
- * HMAC DRBGs are favored over Hash DRBGs over CTR DRBGs, and
- * the SHA256 / AES 256 over other ciphers. Thus, the favored
- * DRBGs are the latest entries in this array.
+ * HMAC DRBGs are favored over Hash DRBGs over CTR DRBGs, and the
+ * HMAC-SHA512 / SHA256 / AES 256 over other ciphers. Thus, the
+ * favored DRBGs are the latest entries in this array.
  */
 static const struct drbg_core drbg_cores[] = {
 #ifdef CONFIG_CRYPTO_DRBG_CTR
@@ -1475,8 +1475,8 @@ static int drbg_generate(struct drbg_state *drbg,
 		int err = 0;
 		pr_devel("DRBG: start to perform self test\n");
 		if (drbg->core->flags & DRBG_HMAC)
-			err = alg_test("drbg_pr_hmac_sha256",
-				       "drbg_pr_hmac_sha256", 0, 0);
+			err = alg_test("drbg_pr_hmac_sha512",
+				       "drbg_pr_hmac_sha512", 0, 0);
 		else if (drbg->core->flags & DRBG_CTR)
 			err = alg_test("drbg_pr_ctr_aes256",
 				       "drbg_pr_ctr_aes256", 0, 0);
@@ -2023,7 +2023,7 @@ static inline int __init drbg_healthcheck_sanity(void)
 	drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
 #endif
 #ifdef CONFIG_CRYPTO_DRBG_HMAC
-	drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr);
+	drbg_convert_tfm_core("drbg_nopr_hmac_sha512", &coreref, &pr);
 #endif
 
 	drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
-- 
2.34.1