keys: Export lookup_user_key to external users

to #27305291

commit 76ef5e17252789da79db78341851922af0c16181 upstream.

Export lookup_user_key() symbol in order to allow nvdimm passphrase
update to retrieve user injected keys.
Signed-off-by: NDave Jiang <dave.jiang@intel.com>
Acked-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>

include/linux/key.h

@@ -346,6 +346,9 @@ static inline key_serial_t key_serial(const struct key *key)
 
 extern void key_set_timeout(struct key *, unsigned);
 
+extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
+				 key_perm_t perm);
+
 /*
  * The permissions required on a key that we're looking up.
  */

security/keys/internal.h

@@ -158,8 +158,6 @@ extern struct key *request_key_and_link(struct key_type *type,
 
 extern bool lookup_user_key_possessed(const struct key *key,
 				      const struct key_match_data *match_data);
-extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
-				 key_perm_t perm);
 #define KEY_LOOKUP_CREATE	0x01
 #define KEY_LOOKUP_PARTIAL	0x02
 #define KEY_LOOKUP_FOR_UNLINK	0x04

security/keys/process_keys.c

@@ -756,6 +756,7 @@ key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
 	put_cred(ctx.cred);
 	goto try_again;
 }
+EXPORT_SYMBOL(lookup_user_key);
 
 /*
  * Join the named keyring as the session keyring if possible else attempt to