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Subject[PATCH 4.14 019/156] crypto: af_alg - whitelist mask and type
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Stephan Mueller <smueller@chronox.de>

commit bb30b8848c85e18ca7e371d0a869e94b3e383bdf upstream.

The user space interface allows specifying the type and mask field used
to allocate the cipher. Only a subset of the possible flags are intended
for user space. Therefore, white-list the allowed flags.

In case the user space caller uses at least one non-allowed flag, EINVAL
is returned.

Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
crypto/af_alg.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -150,7 +150,7 @@ EXPORT_SYMBOL_GPL(af_alg_release_parent)

static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{
- const u32 forbidden = CRYPTO_ALG_INTERNAL;
+ const u32 allowed = CRYPTO_ALG_KERN_DRIVER_ONLY;
struct sock *sk = sock->sk;
struct alg_sock *ask = alg_sk(sk);
struct sockaddr_alg *sa = (void *)uaddr;
@@ -158,6 +158,10 @@ static int alg_bind(struct socket *sock,
void *private;
int err;

+ /* If caller uses non-allowed flag, return error. */
+ if ((sa->salg_feat & ~allowed) || (sa->salg_mask & ~allowed))
+ return -EINVAL;
+
if (sock->state == SS_CONNECTED)
return -EINVAL;

@@ -176,9 +180,7 @@ static int alg_bind(struct socket *sock,
if (IS_ERR(type))
return PTR_ERR(type);

- private = type->bind(sa->salg_name,
- sa->salg_feat & ~forbidden,
- sa->salg_mask & ~forbidden);
+ private = type->bind(sa->salg_name, sa->salg_feat, sa->salg_mask);
if (IS_ERR(private)) {
module_put(type->owner);
return PTR_ERR(private);

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