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Subject[PATCH v4] crypto: AF_ALG - whitelist mask and type
Date
Hi,

sorry, I forgot the right tags.

---8<---

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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
---
crypto/af_alg.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 35d4dcea381f..5231f421ad00 100644
--- 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, struct sockaddr *uaddr, int addr_len)
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, struct sockaddr *uaddr, int addr_len)
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);
--
2.14.3

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