Commit 43e5f1d5 authored by Eric Biggers's avatar Eric Biggers
Browse files

fscrypt: improve fscrypt_destroy_keyring() documentation 

Document that fscrypt_destroy_keyring() must be called after all
potentially-encrypted inodes have been evicted.

Link: https://lore.kernel.org/r/20230313221231.272498-3-ebiggers@kernel.org


Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
parent ccb820dc

fs/crypto/keyring.c

+11 −10
Original line number Diff line number Diff line
@@ -207,10 +207,11 @@ static int allocate_filesystem_keyring(struct super_block *sb) 
 * Release all encryption keys that have been added to the filesystem, along

 * with the keyring that contains them.

 *

 * This is called at unmount time.  The filesystem's underlying block device(s)

 * 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 called at unmount time, after all potentially-encrypted inodes have

 * been evicted.  The filesystem's underlying block device(s) 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).

 */

void fscrypt_destroy_keyring(struct super_block *sb)

{
@@ -227,12 +228,12 @@ void fscrypt_destroy_keyring(struct super_block *sb) 


		hlist_for_each_entry_safe(mk, tmp, bucket, mk_node) {

			/*

			 * Since all inodes were already evicted, every key

			 * remaining in the keyring should have an empty inode

			 * list, and should only still be in the keyring due to

			 * the single active ref associated with ->mk_secret.

			 * There should be no structural refs beyond the one

			 * associated with the active ref.

			 * Since all potentially-encrypted inodes were already

			 * evicted, every key remaining in the keyring should

			 * have an empty inode list, and should only still be in

			 * the keyring due to the single active ref associated

			 * with ->mk_secret.  There should be no structural refs

			 * beyond the one associated with the active ref.

			 */

			WARN_ON(refcount_read(&mk->mk_active_refs) != 1);

			WARN_ON(refcount_read(&mk->mk_struct_refs) != 1);