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crypto: mcryptd - Check mcryptd algorithm compatibility

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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: 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>
This commit is contained in:
tim 2016-12-05 11:46:31 -08:00 committed by Herbert Xu
parent 0c1e16cd1e
commit 48a992727d
1 changed files with 12 additions and 7 deletions
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19
crypto/mcryptd.c
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@ -254,18 +254,22 @@ out_free_inst:
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))