net: move sockfs_xattr_handlers to .rodata

This makes it harder for accidental or malicious changes to
sockfs_xattr_handlers at runtime.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: netdev@vger.kernel.org
Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
Link: https://lore.kernel.org/r/20230930050033.41174-30-wedsonaf@gmail.com
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: wedsonaf

include/linux/pseudo_fs.h

@@ -5,7 +5,7 @@
 
 struct pseudo_fs_context {
 	const struct super_operations *ops;
-	const struct xattr_handler **xattr;
+	const struct xattr_handler * const *xattr;
 	const struct dentry_operations *dops;
 	unsigned long magic;
 };

net/socket.c

@@ -403,7 +403,7 @@ static const struct xattr_handler sockfs_security_xattr_handler = {
 	.set = sockfs_security_xattr_set,
 };
 
-static const struct xattr_handler *sockfs_xattr_handlers[] = {
+static const struct xattr_handler * const sockfs_xattr_handlers[] = {
 	&sockfs_xattr_handler,
 	&sockfs_security_xattr_handler,
 	NULL