github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-07-27 09:36:22 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

crypto: drbg - Clean up generation code

Browse Source 
A few miscellaneous cleanups to make the code a bit more readable:

  - Replace (buf, buflen) with (out, outlen)
  - Update (out, outlen) as we go along
  - Use size_t for lengths
  - Use min()
  - Adjust some comments and log messages
  - Rename a variable named 'len' to 'err', since it isn't a length

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Eric Biggers 2026-04-19 23:34:21 -07:00 committed by Herbert Xu
parent a918c3680d
commit 7cca456c3e
1 changed files with 19 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
crypto/drbg.c
View File

@ -180,12 +180,9 @@ static void drbg_hmac_update(struct drbg_state *drbg,
}
/* generate function of HMAC DRBG as defined in 10.1.2.5 */
static void drbg_hmac_generate(struct drbg_state *drbg,
unsigned char *buf,
unsigned int buflen,
static void drbg_hmac_generate(struct drbg_state *drbg, u8 *out, size_t outlen,
const u8 *addtl1, size_t addtl1_len)
{
int len = 0;
u8 addtl2[32];
size_t addtl2_len = 0;
@ -210,17 +207,16 @@ static void drbg_hmac_generate(struct drbg_state *drbg,
if (addtl1_len || addtl2_len)
drbg_hmac_update(drbg, addtl1, addtl1_len, addtl2, addtl2_len);
while (len < buflen) {
unsigned int outlen = 0;
while (outlen) {
size_t n = min(DRBG_STATE_LEN, outlen);
/* 10.1.2.5 step 4.1 */
hmac_sha512(&drbg->key, drbg->V, DRBG_STATE_LEN, drbg->V);
outlen = (DRBG_STATE_LEN < (buflen - len)) ?
DRBG_STATE_LEN : (buflen - len);
/* 10.1.2.5 step 4.2 */
memcpy(buf + len, drbg->V, outlen);
len += outlen;
memcpy(out, drbg->V, n);
out += n;
outlen -= n;
}
/* 10.1.2.5 step 6 */
@ -331,31 +327,27 @@ static int drbg_seed(struct drbg_state *drbg, const u8 *pers, size_t pers_len,
}
/*
* DRBG generate function as required by SP800-90A - this function
* generates random numbers
* Generate random bytes from an SP800-90A DRBG.
*
* @drbg DRBG state handle
* @buf Buffer where to store the random numbers -- the buffer must already
* be pre-allocated by caller
* @buflen Length of output buffer - this value defines the number of random
* bytes pulled from DRBG
* @out Buffer where to store the random bytes
* @outlen Number of random bytes to generate
* @addtl Optional additional input that is mixed into state
* @addtl_len Length of @addtl in bytes, may be 0
*
* return: 0 when all bytes are generated; < 0 in case of an error
*/
static int drbg_generate(struct drbg_state *drbg,
unsigned char *buf, unsigned int buflen,
static int drbg_generate(struct drbg_state *drbg, u8 *out, size_t outlen,
const u8 *addtl, size_t addtl_len)
__must_hold(&drbg->drbg_mutex)
{
int len = 0;
int err;
if (!drbg->instantiated) {
pr_devel("DRBG: not yet instantiated\n");
return -EINVAL;
}
if (0 == buflen || !buf) {
if (out == NULL || outlen == 0) {
pr_devel("DRBG: no output buffer provided\n");
return -EINVAL;
}
@ -365,9 +357,8 @@ static int drbg_generate(struct drbg_state *drbg,
}
/* 9.3.1 step 2 */
if (buflen > DRBG_MAX_REQUEST_BYTES) {
pr_devel("DRBG: requested random numbers too large %u\n",
buflen);
if (outlen > DRBG_MAX_REQUEST_BYTES) {
pr_devel("DRBG: request length is too long %zu\n", outlen);
return -EINVAL;
}
@ -393,16 +384,16 @@ static int drbg_generate(struct drbg_state *drbg,
pr_devel("DRBG: reseeding before generation (prediction resistance: %s)\n",
str_true_false(drbg->pr));
/* 9.3.1 steps 7.1 through 7.3 */
len = drbg_seed(drbg, addtl, addtl_len, true);
if (len)
goto err;
err = drbg_seed(drbg, addtl, addtl_len, true);
if (err)
return err;
/* 9.3.1 step 7.4 */
addtl = NULL;
addtl_len = 0;
}
/* 9.3.1 step 8 and 10 */
drbg_hmac_generate(drbg, buf, buflen, addtl, addtl_len);
drbg_hmac_generate(drbg, out, outlen, addtl, addtl_len);
/* 10.1.2.5 step 7 */
drbg->reseed_ctr++;
@ -420,13 +411,7 @@ static int drbg_generate(struct drbg_state *drbg,
* correct operation of the DRBG.
*/
/*
* All operations were successful, return 0 as mandated by
* the kernel crypto API interface.
*/
len = 0;
err:
return len;
return 0;
}
/***************************************************************