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authorNeil Horman <nhorman@redhat.com>2009-01-28 15:20:51 +1100
committerHerbert Xu <herbert@gondor.apana.org.au>2009-02-18 16:48:06 +0800
commitd7992f42c61d5dc6d164f7dddd05284485204ada (patch)
tree02e6d942f6859ad9cd0e8d7c2cd56bf84bc2f54a /crypto
parent54b6a1bd5364aca95cd6ffae00f2b64c6511122c (diff)
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crypto: ansi_cprng - Force reset on allocation
Pseudo RNGs provide predictable outputs based on input parateters {key, V, DT}, the idea behind them is that only the user should know what the inputs are. While its nice to have default known values for testing purposes, it seems dangerous to allow the use of those default values without some sort of safety measure in place, lest an attacker easily guess the output of the cprng. This patch forces the NEED_RESET flag on when allocating a cprng context, so that any user is forced to reseed it before use. The defaults can still be used for testing, but this will prevent their inadvertent use, and be more secure. Signed-off-by: Neil Horman <nhorman@redhat.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto')
-rw-r--r--crypto/ansi_cprng.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c
index 0fac8ffc2fb..74478061ac0 100644
--- a/crypto/ansi_cprng.c
+++ b/crypto/ansi_cprng.c
@@ -338,7 +338,16 @@ static int cprng_init(struct crypto_tfm *tfm)
spin_lock_init(&ctx->prng_lock);
- return reset_prng_context(ctx, NULL, DEFAULT_PRNG_KSZ, NULL, NULL);
+ if (reset_prng_context(ctx, NULL, DEFAULT_PRNG_KSZ, NULL, NULL) < 0)
+ return -EINVAL;
+
+ /*
+ * after allocation, we should always force the user to reset
+ * so they don't inadvertently use the insecure default values
+ * without specifying them intentially
+ */
+ ctx->flags |= PRNG_NEED_RESET;
+ return 0;
}
static void cprng_exit(struct crypto_tfm *tfm)