crypto: af_alg - whitelist mask and type

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>
[bwh: Backported to 3.2: The CRYPTO_ALG_KERN_DRIVER_ONLY flag is not supported,
 so set allowed to 0]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 68ec1ac..db3e5ec 100644 (file)
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -149,6 +149,7 @@ EXPORT_SYMBOL_GPL(af_alg_release_parent);
 
 static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 {
 
 static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 {

+       const u32 allowed = 0;

        struct sock *sk = sock->sk;
        struct alg_sock *ask = alg_sk(sk);
        struct sockaddr_alg *sa = (void *)uaddr;
        struct sock *sk = sock->sk;
        struct alg_sock *ask = alg_sk(sk);
        struct sockaddr_alg *sa = (void *)uaddr;


@@ -156,6 +157,10 @@ static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
        void *private;
        int err;
 
        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;
 
        if (sock->state == SS_CONNECTED)
                return -EINVAL;