On Tue, Feb 07, 2023 at 10:57:08AM -0800, Linus Torvalds wrote: > On Tue, Feb 7, 2023 at 10:36 AM Eric Biggers <ebiggers@xxxxxxxxxx> wrote: > > > > Also note that keys are normally added using an ioctl, which can only be > > executed after the filesystem was mounted. The only exception is the key > > associated with the "test_dummy_encryption" mount option. > > Could we perhaps then replace the > > fscrypt_destroy_keyring(s); > > with a more specific > > fscrypt_destroy_dummy_keyring(s); > > thing, that would only handle the dummy encryption case? Sure, they would still need to do most of the same things though. > Or could we just *fix* the dummy encryption test to actually work like > real encryption cases, so that it doesn't have this bogus case? We've wanted to do that for a very long time, but there never has been a way to actually do it. Especially with the filesystem-level keyring now, if the kernel doesn't automatically add the key for test_dummy_encryption, then userspace would have to do it *every time it mounts the filesystem*. The point of the "test_dummy_encryption" mount option is that you can just add it to the mount options and run existing tests, such as a full run of xfstests, and test all the encrypted I/O paths that way. Which is extremely useful; it wouldn't really be possible to properly test the encryption feature without it. So that's why we've gone through some pain to keep "test_dummy_encryption" working over time. Now, it's possible that "the kernel automatically adds the key for test_dummy_encryption" could be implemented a bit differently. It maybe could be done at the last minute, when the key is being looked for due to a user filesystem operation, instead of during the mount itself. That would eliminate the need to call fscrypt_destroy_keyring() from __put_super(), which would avoid the issue being discussed here. I'll see if there's a good way to do that. - Eric
