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-rw-r--r--crypto/ansi_cprng.c35
1 files changed, 25 insertions, 10 deletions
diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c
index 72db0fd763cc..0fac8ffc2fb7 100644
--- a/crypto/ansi_cprng.c
+++ b/crypto/ansi_cprng.c
@@ -161,7 +161,7 @@ static int _get_more_prng_bytes(struct prng_context *ctx)
/*
* Now update our DT value
*/
- for (i = 0; i < DEFAULT_BLK_SZ; i++) {
+ for (i = DEFAULT_BLK_SZ - 1; i >= 0; i--) {
ctx->DT[i] += 1;
if (ctx->DT[i] != 0)
break;
@@ -223,9 +223,10 @@ remainder:
}
/*
- * Copy up to the next whole block size
+ * Copy any data less than an entire block
*/
if (byte_count < DEFAULT_BLK_SZ) {
+empty_rbuf:
for (; ctx->rand_data_valid < DEFAULT_BLK_SZ;
ctx->rand_data_valid++) {
*ptr = ctx->rand_data[ctx->rand_data_valid];
@@ -240,18 +241,22 @@ remainder:
* Now copy whole blocks
*/
for (; byte_count >= DEFAULT_BLK_SZ; byte_count -= DEFAULT_BLK_SZ) {
- if (_get_more_prng_bytes(ctx) < 0) {
- memset(buf, 0, nbytes);
- err = -EINVAL;
- goto done;
+ if (ctx->rand_data_valid == DEFAULT_BLK_SZ) {
+ if (_get_more_prng_bytes(ctx) < 0) {
+ memset(buf, 0, nbytes);
+ err = -EINVAL;
+ goto done;
+ }
}
+ if (ctx->rand_data_valid > 0)
+ goto empty_rbuf;
memcpy(ptr, ctx->rand_data, DEFAULT_BLK_SZ);
ctx->rand_data_valid += DEFAULT_BLK_SZ;
ptr += DEFAULT_BLK_SZ;
}
/*
- * Now copy any extra partial data
+ * Now go back and get any remaining partial block
*/
if (byte_count)
goto remainder;
@@ -349,15 +354,25 @@ 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 +394,7 @@ 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,
}
}
};