On Mon, Oct 16, 2023 at 02:23:37PM -0400, Josef Bacik wrote: > On Sat, Oct 14, 2023 at 11:10:55PM -0700, Eric Biggers wrote: > > From: Eric Biggers <ebiggers@xxxxxxxxxx> > > > > Master keys can be in one of three states: present, incompletely > > removed, and absent (as per FSCRYPT_KEY_STATUS_* used in the UAPI). > > Currently, the way that "present" is distinguished from "incompletely > > removed" internally is by whether ->mk_secret exists or not. > > > > With extent-based encryption, it will be necessary to allow per-extent > > keys to be derived while the master key is incompletely removed, so that > > I/O on open files will reliably continue working after removal of the > > key has been initiated. (We could allow I/O to sometimes fail in that > > case, but that seems problematic for reasons such as writes getting > > silently thrown away and diverging from the existing fscrypt semantics.) > > Therefore, when the filesystem is using extent-based encryption, > > ->mk_secret can't be wiped when the key becomes incompletely removed. > > > > As a prerequisite for doing that, this patch makes the "present" state > > be tracked using a new field, ->mk_present. No behavior is changed yet. > > > > The basic idea here is borrowed from Josef Bacik's patch > > "fscrypt: use a flag to indicate that the master key is being evicted" > > (https://lore.kernel.org/r/e86c16dddc049ff065f877d793ad773e4c6bfad9.1696970227.git.josef@xxxxxxxxxxxxxx). > > I reimplemented it using a "present" bool instead of an "evicted" flag, > > fixed a couple bugs, and tried to update everything to be consistent. > > > > Note: I considered adding a ->mk_status field instead, holding one of > > FSCRYPT_KEY_STATUS_*. At first that seemed nice, but it ended up being > > more complex (despite simplifying FS_IOC_GET_ENCRYPTION_KEY_STATUS), > > since it would have introduced redundancy and had weird locking rules. > > > > Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> > > Based my fscrypt patches ontop of this one, ran tests with both btrfs and ext4 > with it applied, in addition to my normal review stuff. You can add > > Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx> > Thanks. I went ahead and applied this patch to the fscrypt tree. - Eric
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