net/compat.c,linux/filter.h: share compat_sock_fprog

Any other users of bpf_*_filter that take a struct sock_fprog from
userspace will need to be able to also accept a compat_sock_fprog
if the arch supports compat calls.  This change allows the existing
compat_sock_fprog be shared.

Signed-off-by: Will Drewry <wad@chromium.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Eric Paris <eparis@redhat.com>

v18: tasered by the apostrophe police
v14: rebase/nochanges
v13: rebase on to 88ebdda615
v12: rebase on to linux-next
v11: introduction
Signed-off-by: Kevin F. Haggerty <haggertk@lineageos.org>

include/linux/filter.h

@@ -10,6 +10,7 @@
 
 #ifdef __KERNEL__
 #include <linux/atomic.h>
+#include <linux/compat.h>
 #endif
 
 /*
@@ -132,6 +133,16 @@ struct sock_fprog {	/* Required for SO_ATTACH_FILTER. */
 
 #ifdef __KERNEL__
 
+#ifdef CONFIG_COMPAT
+/*
+ * A struct sock_filter is architecture independent.
+ */
+struct compat_sock_fprog {
+	u16		len;
+	compat_uptr_t	filter;		/* struct sock_filter * */
+};
+#endif
+
 struct sk_buff;
 struct sock;
 

net/compat.c

@@ -339,14 +339,6 @@ void scm_detach_fds_compat(struct msghdr *kmsg, struct scm_cookie *scm)
 	__scm_destroy(scm);
 }
 
-/*
- * A struct sock_filter is architecture independent.
- */
-struct compat_sock_fprog {
-	u16		len;
-	compat_uptr_t	filter;		/* struct sock_filter * */
-};
-
 static int do_set_attach_filter(struct socket *sock, int level, int optname,
 				char __user *optval, unsigned int optlen)
 {