Gitweb: http://git.kernel.org/linus/d7992f42c61d5dc6d164f7dddd05284485204ada
Commit: d7992f42c61d5dc6d164f7dddd05284485204ada
Parent: 54b6a1bd5364aca95cd6ffae00f2b64c6511122c
Author: Neil Horman <nhorman@redhat.com>
AuthorDate: Wed Jan 28 15:20:51 2009 +1100
Committer: Herbert Xu <herbert@gondor.apana.org.au>
CommitDate: Wed Feb 18 16:48:06 2009 +0800
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>
---
crypto/ansi_cprng.c | 11 ++++++++++-
1 files changed, 10 insertions(+), 1 deletions(-)
diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c
index 0fac8ff..7447806 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)
--
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