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authorEric Biggers <ebiggers@kernel.org>2026-04-19 23:34:06 -0700
committerHerbert Xu <herbert@gondor.apana.org.au>2026-05-07 16:10:00 +0800
commit245c8d0d177f129d105f84331272494e2cd31f2a (patch)
treead63ba1a9e91a46092b651dcefe9def2ff509e77 /crypto
parentfcc62e0991ff0ceb7f53a93f4b12982b7d91d233 (diff)
downloadlinux-next-history-245c8d0d177f129d105f84331272494e2cd31f2a.tar.gz
crypto: drbg - Use HMAC-SHA512 library API
Since the HMAC algorithm is now fixed at HMAC-SHA512, just use the HMAC-SHA512 library API. This is simpler and more efficient. Remove error-handling code that is no longer needed. Signed-off-by: Eric Biggers <ebiggers@kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto')
-rw-r--r--crypto/Kconfig3
-rw-r--r--crypto/drbg.c213
2 files changed, 41 insertions, 175 deletions
diff --git a/crypto/Kconfig b/crypto/Kconfig
index 1abb3d3564582..608b2c739193f 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -1115,10 +1115,9 @@ menu "Random number generation"
config CRYPTO_DRBG
tristate "NIST SP800-90A DRBG (Deterministic Random Bit Generator)"
- select CRYPTO_HMAC
select CRYPTO_JITTERENTROPY
+ select CRYPTO_LIB_SHA512
select CRYPTO_RNG
- select CRYPTO_SHA512
help
DRBG (Deterministic Random Bit Generator) (NIST SP800-90A)
diff --git a/crypto/drbg.c b/crypto/drbg.c
index e62bde7aab43f..4f326385cf367 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -4,6 +4,7 @@
* both with and without prediction resistance
*
* Copyright Stephan Mueller <smueller@chronox.de>, 2014
+ * Copyright 2026 Google LLC
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@@ -90,7 +91,6 @@
#include <crypto/internal/drbg.h>
#include <crypto/internal/rng.h>
-#include <crypto/hash.h>
#include <crypto/sha2.h>
#include <linux/fips.h>
#include <linux/kernel.h>
@@ -143,12 +143,11 @@ enum drbg_seed_state {
struct drbg_state {
struct mutex drbg_mutex; /* lock around DRBG */
u8 V[DRBG_STATE_LEN]; /* internal state -- 10.1.2.1 1a */
+ struct hmac_sha512_key key; /* current key -- 10.1.2.1 1b */
u8 C[DRBG_STATE_LEN]; /* current key -- 10.1.2.1 1b */
/* Number of RNG requests since last reseed -- 10.1.2.1 1c */
size_t reseed_ctr;
size_t reseed_threshold;
- void *priv_data; /* Cipher handle */
-
enum drbg_seed_state seeded; /* DRBG fully seeded? */
unsigned long last_seed_time;
bool pr; /* Prediction resistance enabled? */
@@ -186,94 +185,67 @@ static int drbg_uninstantiate(struct drbg_state *drbg);
* HMAC DRBG functions
******************************************************************/
-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);
-
MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512");
MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512");
/* update function of HMAC DRBG as defined in 10.1.2.2 */
-static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
- int reseed)
+static void drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
+ int reseed)
{
- int ret = -EFAULT;
int i = 0;
- struct drbg_string seed1, seed2, vdata;
- LIST_HEAD(seedlist);
- LIST_HEAD(vdatalist);
+ struct hmac_sha512_ctx hmac_ctx;
if (!reseed) {
/* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */
memset(drbg->V, 1, DRBG_STATE_LEN);
- drbg_kcapi_hmacsetkey(drbg, drbg->C);
+ hmac_sha512_preparekey(&drbg->key, drbg->C, DRBG_STATE_LEN);
}
- drbg_string_fill(&seed1, drbg->V, DRBG_STATE_LEN);
- list_add_tail(&seed1.list, &seedlist);
- /* buffer of seed2 will be filled in for loop below with one byte */
- drbg_string_fill(&seed2, NULL, 1);
- list_add_tail(&seed2.list, &seedlist);
- /* input data of seed is allowed to be NULL at this point */
- if (seed)
- list_splice_tail(seed, &seedlist);
-
- drbg_string_fill(&vdata, drbg->V, DRBG_STATE_LEN);
- list_add_tail(&vdata.list, &vdatalist);
for (i = 2; 0 < i; i--) {
/* first round uses 0x0, second 0x1 */
unsigned char prefix = DRBG_PREFIX0;
if (1 == i)
prefix = DRBG_PREFIX1;
/* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
- seed2.buf = &prefix;
- ret = drbg_kcapi_hash(drbg, drbg->C, &seedlist);
- if (ret)
- return ret;
- drbg_kcapi_hmacsetkey(drbg, drbg->C);
+ hmac_sha512_init(&hmac_ctx, &drbg->key);
+ hmac_sha512_update(&hmac_ctx, drbg->V, DRBG_STATE_LEN);
+ hmac_sha512_update(&hmac_ctx, &prefix, 1);
+ if (seed) {
+ struct drbg_string *input;
+
+ list_for_each_entry(input, seed, list)
+ hmac_sha512_update(&hmac_ctx, input->buf,
+ input->len);
+ }
+ hmac_sha512_final(&hmac_ctx, drbg->C);
+ hmac_sha512_preparekey(&drbg->key, drbg->C, DRBG_STATE_LEN);
/* 10.1.2.2 step 2 and 5 -- HMAC for V */
- ret = drbg_kcapi_hash(drbg, drbg->V, &vdatalist);
- if (ret)
- return ret;
+ hmac_sha512(&drbg->key, drbg->V, DRBG_STATE_LEN, drbg->V);
/* 10.1.2.2 step 3 */
if (!seed)
- return ret;
+ break;
}
-
- return 0;
}
/* generate function of HMAC DRBG as defined in 10.1.2.5 */
-static int drbg_hmac_generate(struct drbg_state *drbg,
- unsigned char *buf,
- unsigned int buflen,
- struct list_head *addtl)
+static void drbg_hmac_generate(struct drbg_state *drbg,
+ unsigned char *buf,
+ unsigned int buflen,
+ struct list_head *addtl)
{
int len = 0;
- int ret = 0;
- struct drbg_string data;
- LIST_HEAD(datalist);
/* 10.1.2.5 step 2 */
- if (addtl && !list_empty(addtl)) {
- ret = drbg_hmac_update(drbg, addtl, 1);
- if (ret)
- return ret;
- }
+ if (addtl && !list_empty(addtl))
+ drbg_hmac_update(drbg, addtl, 1);
- drbg_string_fill(&data, drbg->V, DRBG_STATE_LEN);
- list_add_tail(&data.list, &datalist);
while (len < buflen) {
unsigned int outlen = 0;
+
/* 10.1.2.5 step 4.1 */
- ret = drbg_kcapi_hash(drbg, drbg->V, &datalist);
- if (ret)
- return ret;
+ hmac_sha512(&drbg->key, drbg->V, DRBG_STATE_LEN, drbg->V);
outlen = (DRBG_STATE_LEN < (buflen - len)) ?
DRBG_STATE_LEN : (buflen - len);
@@ -284,22 +256,15 @@ static int drbg_hmac_generate(struct drbg_state *drbg,
/* 10.1.2.5 step 6 */
if (addtl && !list_empty(addtl))
- ret = drbg_hmac_update(drbg, addtl, 1);
+ drbg_hmac_update(drbg, addtl, 1);
else
- ret = drbg_hmac_update(drbg, NULL, 1);
- if (ret)
- return ret;
-
- return len;
+ drbg_hmac_update(drbg, NULL, 1);
}
-static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed,
- int reseed, enum drbg_seed_state new_seed_state)
+static inline void __drbg_seed(struct drbg_state *drbg, struct list_head *seed,
+ int reseed, enum drbg_seed_state new_seed_state)
{
- int ret = drbg_hmac_update(drbg, seed, reseed);
-
- if (ret)
- return ret;
+ drbg_hmac_update(drbg, seed, reseed);
drbg->seeded = new_seed_state;
drbg->last_seed_time = jiffies;
@@ -325,27 +290,23 @@ static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed,
drbg->reseed_threshold = DRBG_MAX_REQUESTS;
break;
}
-
- return ret;
}
-static int drbg_seed_from_random(struct drbg_state *drbg)
+static void drbg_seed_from_random(struct drbg_state *drbg)
__must_hold(&drbg->drbg_mutex)
{
struct drbg_string data;
LIST_HEAD(seedlist);
unsigned char entropy[DRBG_SEC_STRENGTH];
- int ret;
drbg_string_fill(&data, entropy, DRBG_SEC_STRENGTH);
list_add_tail(&data.list, &seedlist);
get_random_bytes(entropy, DRBG_SEC_STRENGTH);
- ret = __drbg_seed(drbg, &seedlist, true, DRBG_SEED_STATE_FULL);
+ __drbg_seed(drbg, &seedlist, true, DRBG_SEED_STATE_FULL);
memzero_explicit(entropy, DRBG_SEC_STRENGTH);
- return ret;
}
static bool drbg_nopr_reseed_interval_elapsed(struct drbg_state *drbg)
@@ -477,8 +438,8 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
memset(drbg->C, 0, DRBG_STATE_LEN);
}
- ret = __drbg_seed(drbg, &seedlist, reseed, new_seed_state);
-
+ __drbg_seed(drbg, &seedlist, reseed, new_seed_state);
+ ret = 0;
out:
memzero_explicit(entropy, sizeof(entropy));
@@ -490,6 +451,7 @@ static inline void drbg_dealloc_state(struct drbg_state *drbg)
{
if (!drbg)
return;
+ memzero_explicit(&drbg->key, sizeof(drbg->key));
memzero_explicit(drbg->V, sizeof(drbg->V));
memzero_explicit(drbg->C, sizeof(drbg->C));
drbg->reseed_ctr = 0;
@@ -497,24 +459,6 @@ static inline void drbg_dealloc_state(struct drbg_state *drbg)
}
/*
- * Allocate all sub-structures for a DRBG state.
- * The DRBG state structure must already be allocated.
- */
-static inline int drbg_alloc_state(struct drbg_state *drbg)
-{
- int ret = -ENOMEM;
-
- ret = drbg_init_hash_kernel(drbg);
- if (ret < 0)
- goto err;
- return 0;
-
-err:
- drbg_dealloc_state(drbg);
- return ret;
-}
-
-/*
* DRBG generate function as required by SP800-90A - this function
* generates random numbers
*
@@ -590,20 +534,16 @@ static int drbg_generate(struct drbg_state *drbg,
} else if (rng_is_initialized() &&
(drbg->seeded == DRBG_SEED_STATE_PARTIAL ||
drbg_nopr_reseed_interval_elapsed(drbg))) {
- len = drbg_seed_from_random(drbg);
- if (len)
- goto err;
+ drbg_seed_from_random(drbg);
}
if (addtl && 0 < addtl->len)
list_add_tail(&addtl->list, &addtllist);
/* 9.3.1 step 8 and 10 */
- len = drbg_hmac_generate(drbg, buf, buflen, &addtllist);
+ drbg_hmac_generate(drbg, buf, buflen, &addtllist);
/* 10.1.2.5 step 7 */
drbg->reseed_ctr++;
- if (0 >= len)
- goto err;
/*
* Section 11.3.3 requires to re-perform self tests after some
@@ -718,10 +658,6 @@ static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
drbg->last_seed_time = 0;
drbg->reseed_threshold = DRBG_MAX_REQUESTS;
- ret = drbg_alloc_state(drbg);
- if (ret)
- goto unlock;
-
ret = drbg_prepare_hrng(drbg);
if (ret)
goto free_everything;
@@ -737,10 +673,6 @@ static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
mutex_unlock(&drbg->drbg_mutex);
return ret;
-unlock:
- mutex_unlock(&drbg->drbg_mutex);
- return ret;
-
free_everything:
mutex_unlock(&drbg->drbg_mutex);
drbg_uninstantiate(drbg);
@@ -762,7 +694,6 @@ static int drbg_uninstantiate(struct drbg_state *drbg)
crypto_free_rng(drbg->jent);
drbg->jent = NULL;
- drbg_fini_hash_kernel(drbg);
drbg_dealloc_state(drbg);
/* no scrubbing of test_data -- this shall survive an uninstantiate */
return 0;
@@ -786,70 +717,6 @@ static void drbg_kcapi_set_entropy(struct crypto_rng *tfm,
}
/***************************************************************
- * Kernel crypto API cipher invocations requested by DRBG
- ***************************************************************/
-
-struct sdesc {
- struct shash_desc shash;
-};
-
-static int drbg_init_hash_kernel(struct drbg_state *drbg)
-{
- struct sdesc *sdesc;
- struct crypto_shash *tfm;
-
- tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0);
- if (IS_ERR(tfm)) {
- pr_info("DRBG: could not allocate digest TFM handle: %s\n",
- drbg->core->backend_cra_name);
- return PTR_ERR(tfm);
- }
- BUG_ON(DRBG_STATE_LEN != crypto_shash_digestsize(tfm));
- sdesc = kzalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
- GFP_KERNEL);
- if (!sdesc) {
- crypto_free_shash(tfm);
- return -ENOMEM;
- }
-
- sdesc->shash.tfm = tfm;
- drbg->priv_data = sdesc;
-
- return 0;
-}
-
-static int drbg_fini_hash_kernel(struct drbg_state *drbg)
-{
- struct sdesc *sdesc = drbg->priv_data;
- if (sdesc) {
- crypto_free_shash(sdesc->shash.tfm);
- kfree_sensitive(sdesc);
- }
- drbg->priv_data = NULL;
- return 0;
-}
-
-static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
- const unsigned char *key)
-{
- struct sdesc *sdesc = drbg->priv_data;
-
- crypto_shash_setkey(sdesc->shash.tfm, key, DRBG_STATE_LEN);
-}
-
-static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
- const struct list_head *in)
-{
- struct sdesc *sdesc = drbg->priv_data;
- struct drbg_string *input = NULL;
-
- 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);
-}
-
-/***************************************************************
* Kernel crypto API interface to register DRBG
***************************************************************/
generated by cgit 1.3-korg (git 2.53.0) at 2026-06-01 04:07:30 +0000