Re: [PATCH v7 06/16] fscrypt: add FS_IOC_ADD_ENCRYPTION_KEY ioctl

["Theodore Y. Ts'o" <tytso@xxxxxxx>]

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