diff options
| author | Eric Biggers <ebiggers@kernel.org> | 2026-04-19 23:34:21 -0700 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2026-05-07 16:10:01 +0800 |
| commit | 7cca456c3e6a0fefc752e9e93634aa63545d6a68 (patch) | |
| tree | cbd79037ff96bf361507cfe829fb3a8ac8ec9d0c /crypto | |
| parent | a918c3680d2ea1d3c2df589397c0ffd4dac2ceaa (diff) | |
| download | linux-next-history-7cca456c3e6a0fefc752e9e93634aa63545d6a68.tar.gz | |
crypto: drbg - Clean up generation code
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>
Diffstat (limited to 'crypto')
| -rw-r--r-- | crypto/drbg.c | 53 |
1 files changed, 19 insertions, 34 deletions
diff --git a/crypto/drbg.c b/crypto/drbg.c index bab766026177a..b54c807930af8 100644 --- a/crypto/drbg.c +++ b/crypto/drbg.c @@ -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 @@ out: } /* - * 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; } /*************************************************************** |