crypto: af_alg - whitelist mask and type

BugLink: http://bugs.launchpad.net/bugs/1747169
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>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 35d4dcea381fbee7aa312667aa235456bb9d7918..5231f421ad0006663e14b28cf47b577ad0443c83 100644 (file)
--- 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);