Hey all-
This is a patch that was sent to me by Jarod Wilson, marking off my
outstanding todo to allow the ansi cprng to set/reset the DT counter value in a
cprng instance. Currently crytpo_rng_reset accepts a seed byte array which is
interpreted by the ansi_cprng as a {V key} tuple. This patch extends that tuple
to now be {V key DT}, with DT an optional value during reset. This patch also
fixes a bug we noticed in which the offset of the key area of the seed is
started at DEFAULT_PRNG_KSZ rather than DEFAULT_BLK_SZ as it should be.
Regards
Neil
Signed-off-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
ansi_cprng.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c
index 72db0fd..486aa93 100644
--- a/crypto/ansi_cprng.c
+++ b/crypto/ansi_cprng.c
@@ -349,15 +349,25 @@ static int cprng_get_random(struct crypto_rng *tfm, u8 *rdata,
return get_prng_bytes(rdata, dlen, prng);
}
+/*
+ * This is the cprng_registered reset method the seed value is
+ * interpreted as the tuple { V KEY DT}
+ * V and KEY are required during reset, and DT is optional, detected
+ * as being present by testing the length of the seed
+ */
static int cprng_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
{
struct prng_context *prng = crypto_rng_ctx(tfm);
- u8 *key = seed + DEFAULT_PRNG_KSZ;
+ u8 *key = seed + DEFAULT_BLK_SZ;
+ u8 *dt = NULL;
if (slen < DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ)
return -EINVAL;
- reset_prng_context(prng, key, DEFAULT_PRNG_KSZ, seed, NULL);
+ if (slen >= (2 * DEFAULT_BLK_SZ + DEFAULT_PRNG_KSZ))
+ dt = key + DEFAULT_PRNG_KSZ;
+
+ reset_prng_context(prng, key, DEFAULT_PRNG_KSZ, seed, dt);
if (prng->flags & PRNG_NEED_RESET)
return -EINVAL;
@@ -379,7 +389,7 @@ static struct crypto_alg rng_alg = {
.rng = {
.rng_make_random = cprng_get_random,
.rng_reset = cprng_reset,
- .seedsize = DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ,
+ .seedsize = DEFAULT_PRNG_KSZ + 2*DEFAULT_BLK_SZ,
}
}
};
--
/****************************************************
* Neil Horman <nhorman@xxxxxxxxxxxxx>
* Software Engineer, Red Hat
****************************************************/
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