fscrypt: clean up fscrypt_add_test_dummy_key()

Now that fscrypt_add_test_dummy_key() is only called by
setup_file_encryption_key() and not by the individual filesystems,
un-export it.  Also change its prototype to take the
fscrypt_key_specifier directly, as the caller already has it.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20230208062107.199831-6-ebiggers@kernel.org

fs/crypto/fscrypt_private.h

@@ -573,6 +573,9 @@ fscrypt_find_master_key(struct super_block *sb,
 int fscrypt_get_test_dummy_key_identifier(
 			  u8 key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
 
+int fscrypt_add_test_dummy_key(struct super_block *sb,
+			       struct fscrypt_key_specifier *key_spec);
+
 int fscrypt_verify_key_added(struct super_block *sb,
 			     const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
 

fs/crypto/keyring.c

@@ -211,10 +211,6 @@ static int allocate_filesystem_keyring(struct super_block *sb)
  * are still available at this time; this is important because after user file
  * accesses have been allowed, this function may need to evict keys from the
  * keyslots of an inline crypto engine, which requires the block device(s).
- *
- * This is also called when the super_block is being freed.  This is needed to
- * avoid a memory leak if mounting fails after the "test_dummy_encryption"
- * option was processed, as in that case the unmount-time call isn't made.
  */
 void fscrypt_destroy_keyring(struct super_block *sb)
 {
@@ -778,34 +774,26 @@ int fscrypt_get_test_dummy_key_identifier(
 /**
  * fscrypt_add_test_dummy_key() - add the test dummy encryption key
  * @sb: the filesystem instance to add the key to
- * @dummy_policy: the encryption policy for test_dummy_encryption
+ * @key_spec: the key specifier of the test dummy encryption key
  *
- * If needed, add the key for the test_dummy_encryption mount option to the
- * filesystem.  To prevent misuse of this mount option, a per-boot random key is
- * used instead of a hardcoded one.  This makes it so that any encrypted files
- * created using this option won't be accessible after a reboot.
+ * Add the key for the test_dummy_encryption mount option to the filesystem.  To
+ * prevent misuse of this mount option, a per-boot random key is used instead of
+ * a hardcoded one.  This makes it so that any encrypted files created using
+ * this option won't be accessible after a reboot.
  *
  * Return: 0 on success, -errno on failure
  */
 int fscrypt_add_test_dummy_key(struct super_block *sb,
-			       const struct fscrypt_dummy_policy *dummy_policy)
+			       struct fscrypt_key_specifier *key_spec)
 {
-	const union fscrypt_policy *policy = dummy_policy->policy;
-	struct fscrypt_key_specifier key_spec;
 	struct fscrypt_master_key_secret secret;
 	int err;
 
-	if (!policy)
-		return 0;
-	err = fscrypt_policy_to_key_spec(policy, &key_spec);
-	if (err)
-		return err;
 	fscrypt_get_test_dummy_secret(&secret);
-	err = add_master_key(sb, &secret, &key_spec);
+	err = add_master_key(sb, &secret, key_spec);
 	wipe_master_key_secret(&secret);
 	return err;
 }
-EXPORT_SYMBOL_GPL(fscrypt_add_test_dummy_key);
 
 /*
  * Verify that the current user has added a master key with the given identifier

fs/crypto/keysetup.c

@@ -464,9 +464,7 @@ static int setup_file_encryption_key(struct fscrypt_info *ci,
 		 */
 		if (dummy_policy &&
 		    fscrypt_policies_equal(dummy_policy, &ci->ci_policy)) {
-			struct fscrypt_dummy_policy tmp = { dummy_policy };
-
-			err = fscrypt_add_test_dummy_key(sb, &tmp);
+			err = fscrypt_add_test_dummy_key(sb, &mk_spec);
 			if (err)
 				return err;
 			mk = fscrypt_find_master_key(sb, &mk_spec);

include/linux/fscrypt.h

@@ -309,8 +309,6 @@ fscrypt_free_dummy_policy(struct fscrypt_dummy_policy *dummy_policy)
 /* keyring.c */
 void fscrypt_destroy_keyring(struct super_block *sb);
 int fscrypt_ioctl_add_key(struct file *filp, void __user *arg);
-int fscrypt_add_test_dummy_key(struct super_block *sb,
-			       const struct fscrypt_dummy_policy *dummy_policy);
 int fscrypt_ioctl_remove_key(struct file *filp, void __user *arg);
 int fscrypt_ioctl_remove_key_all_users(struct file *filp, void __user *arg);
 int fscrypt_ioctl_get_key_status(struct file *filp, void __user *arg);
@@ -530,13 +528,6 @@ static inline int fscrypt_ioctl_add_key(struct file *filp, void __user *arg)
 	return -EOPNOTSUPP;
 }
 
-static inline int
-fscrypt_add_test_dummy_key(struct super_block *sb,
-			   const struct fscrypt_dummy_policy *dummy_policy)
-{
-	return 0;
-}
-
 static inline int fscrypt_ioctl_remove_key(struct file *filp, void __user *arg)
 {
 	return -EOPNOTSUPP;