[PATCH 06/38] crypto: drbg - Remove always-enabled symbol CRYPTO_DRBG_HMAC
From: Eric Biggers
Date: Mon Apr 20 2026 - 02:40:20 EST
The kconfig symbol CRYPTO_DRBG_HMAC is always enabled when
CRYPTO_DRBG_MENU is enabled, and all checks for CRYPTO_DRBG_HMAC are in
code conditional on CRYPTO_DRBG_MENU. Thus, the only purpose of the
CRYPTO_DRBG_HMAC symbol is to select CRYPTO_HMAC and CRYPTO_SHA512.
Move those two selections to CRYPTO_DRBG_MENU, remove the checks for
CRYPTO_DRBG_HMAC, and remove the CRYPTO_DRBG_HMAC symbol itself.
Note that this also fixes an issue where CRYPTO_HMAC and CRYPTO_SHA512
were unnecessarily being forced to built-in when CRYPTO_DRBG=m.
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
crypto/Kconfig | 10 +++-------
crypto/drbg.c | 15 ---------------
2 files changed, 3 insertions(+), 22 deletions(-)
diff --git a/crypto/Kconfig b/crypto/Kconfig
index 103d1f58cb7c..34da01c153d6 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -1120,16 +1120,10 @@ menuconfig CRYPTO_DRBG_MENU
In the following submenu, one or more of the DRBG types must be selected.
if CRYPTO_DRBG_MENU
-config CRYPTO_DRBG_HMAC
- bool
- default y
- select CRYPTO_HMAC
- select CRYPTO_SHA512
-
config CRYPTO_DRBG_HASH
bool "Hash_DRBG"
select CRYPTO_SHA256
help
Hash_DRBG variant as defined in NIST SP800-90A.
@@ -1145,12 +1139,14 @@ config CRYPTO_DRBG_CTR
This uses the AES cipher algorithm with the counter block mode.
config CRYPTO_DRBG
tristate
default CRYPTO_DRBG_MENU
- select CRYPTO_RNG
+ select CRYPTO_HMAC
select CRYPTO_JITTERENTROPY
+ select CRYPTO_RNG
+ select CRYPTO_SHA512
endif # if CRYPTO_DRBG_MENU
config CRYPTO_JITTERENTROPY
tristate "CPU Jitter Non-Deterministic RNG (Random Number Generator)"
diff --git a/crypto/drbg.c b/crypto/drbg.c
index e3065fb9541b..f6bff275c31b 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -159,11 +159,10 @@ static const struct drbg_core drbg_cores[] = {
.blocklen_bytes = 32,
.cra_name = "sha256",
.backend_cra_name = "sha256",
},
#endif /* CONFIG_CRYPTO_DRBG_HASH */
-#ifdef CONFIG_CRYPTO_DRBG_HMAC
{
.flags = DRBG_HMAC | DRBG_STRENGTH256,
.statelen = 48, /* block length of cipher */
.blocklen_bytes = 48,
.cra_name = "hmac_sha384",
@@ -179,11 +178,10 @@ static const struct drbg_core drbg_cores[] = {
.statelen = 64, /* block length of cipher */
.blocklen_bytes = 64,
.cra_name = "hmac_sha512",
.backend_cra_name = "hmac(sha512)",
},
-#endif /* CONFIG_CRYPTO_DRBG_HMAC */
};
static int drbg_uninstantiate(struct drbg_state *drbg);
/******************************************************************
@@ -404,20 +402,17 @@ static const struct drbg_state_ops drbg_ctr_ops = {
/******************************************************************
* HMAC DRBG callback functions
******************************************************************/
-#if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
const struct list_head *in);
static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
const unsigned char *key);
static int drbg_init_hash_kernel(struct drbg_state *drbg);
static int drbg_fini_hash_kernel(struct drbg_state *drbg);
-#endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
-#ifdef CONFIG_CRYPTO_DRBG_HMAC
#define CRYPTO_DRBG_HMAC_STRING "HMAC "
MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512");
MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512");
MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha384");
MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha384");
@@ -525,11 +520,10 @@ static const struct drbg_state_ops drbg_hmac_ops = {
.update = drbg_hmac_update,
.generate = drbg_hmac_generate,
.crypto_init = drbg_init_hash_kernel,
.crypto_fini = drbg_fini_hash_kernel,
};
-#endif /* CONFIG_CRYPTO_DRBG_HMAC */
/******************************************************************
* Hash DRBG callback functions
******************************************************************/
@@ -1044,15 +1038,13 @@ static inline int drbg_alloc_state(struct drbg_state *drbg)
{
int ret = -ENOMEM;
unsigned int sb_size = 0;
switch (drbg->core->flags & DRBG_TYPE_MASK) {
-#ifdef CONFIG_CRYPTO_DRBG_HMAC
case DRBG_HMAC:
drbg->d_ops = &drbg_hmac_ops;
break;
-#endif /* CONFIG_CRYPTO_DRBG_HMAC */
#ifdef CONFIG_CRYPTO_DRBG_HASH
case DRBG_HASH:
drbg->d_ops = &drbg_hash_ops;
break;
#endif /* CONFIG_CRYPTO_DRBG_HASH */
@@ -1429,11 +1421,10 @@ static void drbg_kcapi_set_entropy(struct crypto_rng *tfm,
/***************************************************************
* Kernel crypto API cipher invocations requested by DRBG
***************************************************************/
-#if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
struct sdesc {
struct shash_desc shash;
};
static int drbg_init_hash_kernel(struct drbg_state *drbg)
@@ -1489,11 +1480,10 @@ static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
crypto_shash_init(&sdesc->shash);
list_for_each_entry(input, in, list)
crypto_shash_update(&sdesc->shash, input->buf, input->len);
return crypto_shash_final(&sdesc->shash, outval);
}
-#endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
#ifdef CONFIG_CRYPTO_DRBG_CTR
static int drbg_fini_sym_kernel(struct drbg_state *drbg)
{
struct aes_enckey *aeskey = drbg->priv_data;
@@ -1755,13 +1745,11 @@ static inline int __init drbg_healthcheck_sanity(void)
drbg_convert_tfm_core("drbg_nopr_ctr_aes256", &coreref, &pr);
#endif
#ifdef CONFIG_CRYPTO_DRBG_HASH
drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
#endif
-#ifdef CONFIG_CRYPTO_DRBG_HMAC
drbg_convert_tfm_core("drbg_nopr_hmac_sha512", &coreref, &pr);
-#endif
drbg = kzalloc_obj(struct drbg_state);
if (!drbg)
return -ENOMEM;
@@ -1885,13 +1873,10 @@ static void __exit drbg_exit(void)
module_init(drbg_init);
module_exit(drbg_exit);
#ifndef CRYPTO_DRBG_HASH_STRING
#define CRYPTO_DRBG_HASH_STRING ""
#endif
-#ifndef CRYPTO_DRBG_HMAC_STRING
-#define CRYPTO_DRBG_HMAC_STRING ""
-#endif
#ifndef CRYPTO_DRBG_CTR_STRING
#define CRYPTO_DRBG_CTR_STRING ""
#endif
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Stephan Mueller <smueller@xxxxxxxxxx>");
--
2.53.0