From: Stephan Mueller <smueller@chronox.de>
Date: Tue, 2 Jan 2018 07:55:25 +0000 (+0100)
Subject: crypto: af_alg - whitelist mask and type
X-Git-Tag: archive/raspbian/4.9.80-2+rpi1~7^2~77
X-Git-Url: https://dgit.raspbian.org/%22http:/www.example.com/%22mailto:kde%40ewsoftware.de//%22style.css/%22/%22http:/www.example.com/%22mailto:kde%40ewsoftware.de/%22style.css/%22?a=commitdiff_plain;h=b7edc45f3adace20d74788dd4d5a085c134ba6be;p=linux-4.9.git

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index f5e18c2a4852..ca50eeb13097 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -149,7 +149,7 @@ 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;
@@ -157,6 +157,10 @@ 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;
 
@@ -175,9 +179,7 @@ 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);