Qubes OS Admin API

(This page is the current draft of the proposal. It is not implemented yet.)

Goals

The goals of the Admin API system is to provide a way for the user to manage the domains without direct access to dom0.

Foreseen benefits include:

  • Ability to remotely manage the Qubes OS.
  • Possibility to create multi-user system, where different users are able to use different sets of domains, possibly overlapping. This would also require to have separate GUI domain.

The API would be used by:

  • Qubes OS Manager (or any tools that would replace it)
  • CLI tools, when run from another VM (and possibly also from dom0)
  • remote management tools
  • any custom tools

Threat model

TBD

Components

Admin API Architecture

A central entity in the Qubes Admin API system is a qubesd daemon, which holds information about all domains in the system and mediates all actions (like starting and stopping a qube) with libvirtd. The qubesd daemon also manages the qubes.xml file, which stores all persistent state information and dispatches events to extensions. Last but not least, qubesd is responsible for querying the RPC policy for qrexec daemon.

The qubesd daemon may be accessed from other domains through a set of qrexec API calls called the “Admin API”. This API is the intended management interface supported by the Qubes OS. The API is stable. When called, the RPC handler performs basic validation and forwards the request to the qubesd via UNIX domain socket. The socket API is private and unstable. It is documented [FIXME currently it isn’t – woju 20161221] in the developer’s documentation of the source code.

The calls

The API should be implemented as a set of qrexec calls. This is to make it easy to set the policy using current mechanism.

call dest argument inside return note  
admin.vmclass.List dom0 - - <class>\n    
admin.vm.List dom0|<vm> - - <name> class=<class> state=<state>\n    
admin.vm.Create.<class> dom0 template name=<name> label=<label> -    
admin.vm.CreateInPool.<class> dom0 template name=<name> label=<label>
pool=<pool> pool:<volume>=<pool>
- either use pool= to put all volumes there,
or pool:<volume>= for individual volumes - both forms are not allowed at the same time
 
admin.vm.CreateDisposable template - - name Create new DisposableVM, template is any AppVM with dispvm_allowed set to True, or dom0 to use default defined in default_dispvm property of calling VM; VM created with this call will be automatically removed after its shutdown; the main difference from admin.vm.Create.DispVM is automatic (random) name generation.  
admin.vm.Remove vm - - -    
admin.label.List dom0 - - <property>\n    
admin.label.Create dom0 label 0xRRGGBB -    
admin.label.Get dom0 label - 0xRRGGBB    
admin.label.Index dom0 label - <label-index>    
admin.label.Remove dom0 label - -    
admin.property.List dom0 - - <property>\n    
admin.property.Get dom0 property - default={True|False}
type={str|int|bool|vm|label} <value>
   
admin.property.GetDefault dom0 property - type={str|int|bool|vm|label} <value>    
admin.property.Help dom0 property - help    
admin.property.HelpRst dom0 property - help.rst    
admin.property.Reset dom0 property - -    
admin.property.Set dom0 property value -    
admin.vm.property.List vm - - <property>\n    
admin.vm.property.Get vm property - default={True|False}
type={str|int|bool|vm|label} <value>
   
admin.vm.property.GetDefault vm property - type={str|int|bool|vm|label} <value>    
admin.vm.property.Help vm property - help    
admin.vm.property.HelpRst vm property - help.rst    
admin.vm.property.Reset vm property - -    
admin.vm.property.Set vm property value -    
admin.vm.feature.List vm - - <feature>\n    
admin.vm.feature.Get vm feature - value    
admin.vm.feature.CheckWithTemplate vm feature - value    
admin.vm.feature.Remove vm feature - -    
admin.vm.feature.Set vm feature value -    
admin.vm.tag.List vm - - <tag>\n    
admin.vm.tag.Get vm tag - 0 or 1 retcode?  
admin.vm.tag.Remove vm tag - -    
admin.vm.tag.Set vm tag - -    
admin.vm.firewall.Get vm - - <rule>\n rules syntax as in firewall interface with addition of expire= and comment= options; comment= (if present) must be the last option  
admin.vm.firewall.Set vm - <rule>\n - set firewall rules, see admin.vm.firewall.Get for syntax  
admin.vm.firewall.Reload vm - - - force reload firewall without changing any rule  
admin.vm.device.<class>.Attach vm device options - device is in form <backend-name>+<device-ident>
optional options given in key=value format, separated with spaces;
options can include persistent=True to “persistently” attach the device (default is temporary)
 
admin.vm.device.<class>.Detach vm device - - device is in form <backend-name>+<device-ident>  
admin.vm.device.<class>.Set.persistent vm device True False - device is in form <backend-name>+<device-ident>
admin.vm.device.<class>.List vm - - <device> <options>\n options can include persistent=True for “persistently” attached devices (default is temporary)  
admin.vm.device.<class>.Available vm device-ident - <device-ident> <properties> description=<desc>\n optional service argument may be used to get info about a single device,
optional (device class specific) properties are in key=value form,
description must be the last one and is the only one allowed to contain spaces
 
admin.pool.List dom0 - - <pool>\n    
admin.pool.ListDrivers dom0 - - <pool-driver> <property> ...\n Properties allowed in admin.pool.Add  
admin.pool.Info dom0 pool - <property>=<value>\n    
admin.pool.Add dom0 driver <property>=<value>\n -    
admin.pool.Set.revisions_to_keep dom0 pool <value> -    
admin.pool.Remove dom0 pool - -    
admin.pool.volume.List dom0 pool - volume id    
admin.pool.volume.Info dom0 pool vid <property>=<value>\n    
admin.pool.volume.Set.revisions_to_keep dom0 pool <vid> <value> -    
admin.pool.volume.ListSnapshots dom0 pool vid <snapshot>\n    
admin.pool.volume.Snapshot dom0 pool vid snapshot    
admin.pool.volume.Revert dom0 pool <vid> <snapshot> -    
admin.pool.volume.Resize dom0 pool <vid> <size_in_bytes> -    
admin.pool.volume.Import dom0 pool <vid>\n<raw volume data> -    
admin.pool.volume.CloneFrom dom0 pool vid token, to be used in admin.pool.volume.CloneTo obtain a token to copy volume vid in pool;
the token is one time use only, it’s invalidated by admin.pool.volume.CloneTo, even if the operation fails
 
admin.pool.volume.CloneTo dom0 pool <vid> <token> - copy volume pointed by a token to volume vid in pool  
admin.vm.volume.List vm - - <volume>\n <volume> is per-VM volume name (root, private, etc), <vid> is pool-unique volume id  
admin.vm.volume.Info vm volume - <property>=<value>\n    
admin.vm.volume.Set.revisions_to_keep vm volume value -    
admin.vm.volume.ListSnapshots vm volume - snapshot duplicate of admin.pool.volume., but with other call params  
admin.vm.volume.Snapshot vm volume - snapshot id.  
admin.vm.volume.Revert vm volume snapshot - id.  
admin.vm.volume.Resize vm volume size_in_bytes - id.  
admin.vm.volume.Import vm volume raw volume data - id.  
admin.vm.volume.CloneFrom vm volume - token, to be used in admin.vm.volume.CloneTo obtain a token to copy volume of vm;
the token is one time use only, it’s invalidated by admin.vm.volume.CloneTo, even if the operation fails
 
admin.vm.volume.CloneTo vm volume token, obtained with admin.vm.volume.CloneFrom - copy volume pointed by a token to volume of vm  
admin.vm.Start vm - - -    
admin.vm.Shutdown vm - - -    
admin.vm.Pause vm - - -    
admin.vm.Unpause vm - - -    
admin.vm.Kill vm - - -    
admin.backup.Execute dom0 config id - - config in /etc/qubes/backup/<id>.conf, only one backup operation of given config id can be running at once  
admin.backup.Info dom0 config id - backup info info what would be included in the backup  
admin.backup.Cancel dom0 config id - - cancel running backup operation  
admin.Events dom0|vm - - events    
admin.vm.Stats dom0|vm - - vm-stats events, see below emit VM statistics (CPU, memory usage) in form of events  

Volume properties:

  • pool
  • vid
  • size
  • usage
  • rw
  • source
  • save_on_stop
  • snap_on_start

Method admin.vm.Stats returns vm-stats events every stats_interval seconds, for every running VM. Parameters of vm-stats events:

  • memory_kb - memory usage in kB
  • cpu_time - absolute CPU time (in milliseconds) spent by the VM since its startup, normalized for one CPU
  • cpu_usage - CPU usage in percents

Returned messages

First byte of a message is a message type. This is 8 bit non-zero integer. Values start at 0x30 (48, '0', zero digit in ASCII) for readability in hexdump. Next byte must be 0x00 (a separator).

This alternatively can be thought of as zero-terminated string containing single ASCII digit.

OK (0)

30 00 <content>

Server will close the connection after delivering single message.

EVENT (1)

31 00 <subject> 00 <event> 00 ( <key> 00 <value> 00 )* 00

Events are returned as stream of messages in selected API calls. Normally server will not close the connection.

A method yielding events will not ever return a OK or EXCEPTION message.

When calling such method, it will produce an artificial event connection-established just after connection, to help avoiding race conditions during event handler registration.

EXCEPTION (2)

32 00 <type> 00 ( <traceback> )? 00 <format string> 00 ( <field> 00 )*

Server will close the connection.

Traceback may be empty, can be enabled server-side as part of debug mode. Delimiting zero-byte is always present.

Fields are should substituted into %-style format string, possibly after client-side translation, to form final message to be displayed unto user. Server does not by itself support translation.

Tags

The tags provided can be used to write custom policies. They are not used in a default Qubes OS installation. However, they are created anyway.

  • created-by-<vm> — Created in an extension to qubesd at the moment of creation of the VM. Cannot be changed via API, which is also enforced by this extension.
  • managed-by-<vm> — Can be used for the same purpose, but it is not created automatically, nor is it forbidden to set or reset this tag.

Backup profile

Backup-related calls do not allow (yet) to specify what should be included in the backup. This needs to be configured separately in dom0, with a backup profile, stored in /etc/qubes/backup/<profile>.conf. The file use yaml syntax and have following settings:

  • include - list of VMs to include, can also contains tags using $tag:some-tag syntax or all VMs of given type using $type:AppVM, known from qrexec policy
  • exclude - list of VMs to exclude, after evaluating include setting
  • destination_vm - VM to which the backup should be send
  • destination_path - path to which backup should be written in destination_vm. This setting is given to qubes.Backup service and technically it’s up to it how to interpret it. In current implementation it is interpreted as a directory where a new file should be written (with a name based on the current timestamp), or a command where the backup should be piped to
  • compression - should the backup be compressed (default: True)? The value can be either False or True for default compression, or a compression command (needs to accept -d argument for decompression)
  • passphrase_text - passphrase used to encrypt and integrity protect the backup
  • passphrase_vm - VM which should be asked what backup passphrase should be used. The asking is performed using qubes.BackupPassphrase+profile_name service, which is expected to output chosen passphrase to its stdout. Empty output cancel the backup operation. This service can be used either to ask the user interactively, or to have some automated passphrase handling (for example: generate randomly, then encrypt with a public key and send somewhere)

Not all settings needs to be set.

Example backup profile:

# Backup only selected VMs
include:
  - work
  - personal
  - vault
  - banking

# Store the backup on external disk
destination_vm: sys-usb
destination_path: /media/my-backup-disk

# Use static passphrase
passphrase_text: "My$Very!@Strong23Passphrase"

And slightly more advanced one:

# Include all VMs with a few exceptions
include:
  - $type:AppVM
  - $type:TemplateVM
  - $type:StandaloneVM
exclude:
  - untrusted
  - $tag:do-not-backup

# parallel gzip for faster backup
compression: pigz

# ask 'vault' VM for the backup passphrase
passphrase_vm: vault

# send the (encrypted) backup directly to remote server
destination_vm: sys-net
destination_path: ncftpput -u my-ftp-username -p my-ftp-pass -c my-ftp-server /directory/for/backups

General notes

  • there is no provision for qvm-run, but there already exists qubes.VMShell call
  • generally actions *.List return a list of objects and have “object identifier” as first word in a row. Such action can be also called with “object identifier” in argument to get only a single entry (in the same format).
  • closing qrexec connection normally does not interrupt running operation; this is important to avoid leaving the system in inconsistent state
  • actual operation starts only after caller send all the parameters (including a payload), signaled by sending EOF mark; there is no support for interactive protocols, to keep the protocol reasonable simple

TODO

  • something to configure/update policy
  • notifications
    • how to constrain the events?
    • how to pass the parameters? maybe XML, since this is trusted anyway and parser may be complicated
  • how to constrain the possible values for admin.vm.property.Set etc, like “you can change netvm, but you have to pick from this set”; this currently can be done by writing an extension
  • a call for executing *.desktop file from /usr/share/applications, for use with appmenus without giving access to qubes.VMShell; currently this can be done by writing custom qrexec calls
  • maybe some generator for .desktop for appmenus, which would wrap calls in qrexec-client-vm