btrfs send non-root
I'm getting an error when trying to send a subvolume. I only seem to be able to do this as root. The subvolume was created by the user account, and not root. Could anybody shed some light on why this is failing? Is there a way to get it working?
$ btrfs send /var/spool/backups/hacking/2017-03-10 > something ERROR: cannot open '/': Operation not permitted
Also appears I cannot even use btrfs subvolume show:
$ btrfs subvolume show /var/spool/backups/hacking/2017-03-10 ERROR: can't perform the search - Operation not permitted ERROR: can't find 'var/spool/backups/hacking/2017-03-10'
$ sudo btrfs subvolume show /var/spool/backups/hacking/2017-03-10 /var/spool/backups/hacking/2017-03-10 Name: 2017-03-10 UUID: c3a92646-bd6b-7a4f-ae10- 8bd12e569772 Parent UUID: 38b66de9-84d3-4848-ae53- 9a2fe861618c Received UUID: - Creation time: 2017-03-10 19:11:22 +0000 Subvolume ID: 564 Generation: 753377 Gen at creation: 753377 Parent ID: 257 Top level ID: 257 Flags: readonly Snapshot(s):
$ uname -a Linux sam-laptop 4.4.0-66-generic #87-Ubuntu SMP Fri Mar 3 15:29:05 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
$ btrfs --version btrfs-progs v4.4
Quoted 7 lines · Sam Bull
I'm getting an error when trying to send a subvolume. I only seem to be able to do this as root. The subvolume was created by the user account, and not root. Could anybody shed some light on why this is failing? Is there a way to get it working?
$ btrfs send /var/spool/backups/hacking/2017-03-10 > something ERROR: cannot open '/': Operation not permitted
The send operation for non-root would need a full evaluation whether it does not cross the permissions/security boundaries.
Quoted 5 lines
Also appears I cannot even use btrfs subvolume show:
$ btrfs subvolume show /var/spool/backups/hacking/2017-03-10 ERROR: can't perform the search - Operation not permitted ERROR: can't find 'var/spool/backups/hacking/2017-03-10'
The reason here is that the TREE_SEACH ioctl is used, that gives full access to the internal structures and therefore is root-only. Many 'btrfs' subcommands utilize the flexibility of the ioctl as we don't have tons of specialized ioctls, but this comes at some cost.