[PATCH 4.14 27/67] xfrm: Refuse to insert 32 bit userspace socket policies on 64 bit systems

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

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

From: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>

commit 19d7df69fdb2636856dc8919de72fc1bf8f79598 upstream.

We don't have a compat layer for xfrm, so userspace and kernel
structures have different sizes in this case. This results in
a broken configuration, so refuse to configure socket policies
when trying to insert from 32 bit userspace as we do it already
with policies inserted via netlink.

Reported-and-tested-by: syzbot+e1a1577ca8bcb47b769a@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/xfrm/xfrm_state.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -2050,6 +2050,11 @@ int xfrm_user_policy(struct sock *sk, in
 	struct xfrm_mgr *km;
 	struct xfrm_policy *pol = NULL;
 
+#ifdef CONFIG_COMPAT
+	if (in_compat_syscall())
+		return -EOPNOTSUPP;
+#endif
+
 	if (!optval && !optlen) {
 		xfrm_sk_policy_insert(sk, XFRM_POLICY_IN, NULL);
 		xfrm_sk_policy_insert(sk, XFRM_POLICY_OUT, NULL);