On Mon, Jul 29, 2019 at 12:46:45PM -0700, Eric Biggers wrote:

quoted

For that matter, we could just add a new ioctl which returns the file
system's keyring id.  That way an application program won't have to
try to figure out what a file's underlying sb->s_id happens to be.
(Especially if things like overlayfs are involved.)

Keep in mind that the new ioctls (FS_IOC_ADD_ENCRYPTION_KEY,
FS_IOC_REMOVE_ENCRYPTION_KEY, FS_IOC_GET_ENCRYPTION_KEY_STATUS) don't take the
keyring ID as a parameter, since it's already known from the filesystem the
ioctl is executed on.  So there actually isn't much that can be done with the
keyring ID.  But sure, if it's needed later we can add an API to get it.

Yeah, I was thinking about for testing/debugging purposes so that we
could use keyctl to examine the per-file system keyring and see what
keys are attached to a file system.  This is only going to be usable
by root, so I guess we can just try to figure it out by going through
/proc/keys and searching by sb->s_id.  If there are ambiguities that
make this hard to do, we can add an interface to make this easier.

     	       	      	     - Ted

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