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Commit 48a99272 authored by tim's avatar tim Committed by Herbert Xu
Browse files

crypto: mcryptd - Check mcryptd algorithm compatibility 

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


Cc: stable@vger.kernel.org
Reported-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarTim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 0c1e16cd

crypto/mcryptd.c

+12 −7
Original line number Diff line number Diff line
@@ -254,18 +254,22 @@ static void *mcryptd_alloc_instance(struct crypto_alg *alg, unsigned int head, 
	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)
@@ -492,7 +496,8 @@ static int mcryptd_create_hash(struct crypto_template *tmpl, struct rtattr **tb, 
	u32 mask = 0;

	int err;



	mcryptd_check_internal(tb, &type, &mask);

	if (!mcryptd_check_internal(tb, &type, &mask))

		return -EINVAL;



	halg = ahash_attr_alg(tb[1], type, mask);

	if (IS_ERR(halg))