crypto: mcryptd - Check mcryptd algorithm compatibility
commit 48a992727d82cb7db076fa15d372178743b1f4cd upstream.
Algorithms not compatible with mcryptd could be spawned by mcryptd
with a direct crypto_alloc_tfm invocation using a "mcryptd(alg)" name
construct. This causes mcryptd to crash the kernel if an arbitrary
"alg" is incompatible and not intended to be used with mcryptd. It is
an issue if AF_ALG tries to spawn mcryptd(alg) to expose it externally.
But such algorithms must be used internally and not be exposed.
We added a check to enforce that only internal algorithms are allowed
with mcryptd at the time mcryptd is spawning an algorithm.
Link: http://marc.info/?l=linux-crypto-vger&m=148063683310477&w=2
Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/crypto/mcryptd.c b/crypto/mcryptd.c
index fe5b495a..a0ceb41 100644
--- a/crypto/mcryptd.c
+++ b/crypto/mcryptd.c
@@ -258,18 +258,22 @@
goto out;
}
-static inline void mcryptd_check_internal(struct rtattr **tb, u32 *type,
+static inline bool mcryptd_check_internal(struct rtattr **tb, u32 *type,
u32 *mask)
{
struct crypto_attr_type *algt;
algt = crypto_get_attr_type(tb);
if (IS_ERR(algt))
- return;
- if ((algt->type & CRYPTO_ALG_INTERNAL))
- *type |= CRYPTO_ALG_INTERNAL;
- if ((algt->mask & CRYPTO_ALG_INTERNAL))
- *mask |= CRYPTO_ALG_INTERNAL;
+ return false;
+
+ *type |= algt->type & CRYPTO_ALG_INTERNAL;
+ *mask |= algt->mask & CRYPTO_ALG_INTERNAL;
+
+ if (*type & *mask & CRYPTO_ALG_INTERNAL)
+ return true;
+ else
+ return false;
}
static int mcryptd_hash_init_tfm(struct crypto_tfm *tfm)
@@ -498,7 +502,8 @@
u32 mask = 0;
int err;
- mcryptd_check_internal(tb, &type, &mask);
+ if (!mcryptd_check_internal(tb, &type, &mask))
+ return -EINVAL;
salg = shash_attr_alg(tb[1], type, mask);
if (IS_ERR(salg))
