xfrm: Refuse to insert 32 bit userspace socket policies on 64 bit systems

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@syzkaller.appspotmail.com
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 54e21f19d722..f9d2f2233f09 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -2056,6 +2056,11 @@ int xfrm_user_policy(struct sock *sk, int optname, u8 __user *optval, int optlen
         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);