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

BugLink: http://bugs.launchpad.net/bugs/1762370
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@syzkaller.appspotmail.com
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 54e21f19d722c43d0b1fd102777a3467cee5b009..f9d2f2233f09531697b35209fe86754d23971e3f 100644 (file)
--- 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);