qubes-doc/developer/services/admin-api.md

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Qubes OS Admin API

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

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	`	-	-	<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} <br/>type={str
admin.property.GetAll	dom0	-	-	<property-name> <full-value-as-in-property.Get>\n	Get all the properties in one call. Each property is returned on a separate line and use the same value encoding as property.Get method, with an exception that newlines are encoded as literal \n and literal \ are encoded as \\.
admin.property.GetDefault	dom0	property	-	`type={str	int
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} <br/>type={str
admin.vm.property.GetAll	vm	-	-	<property-name> <full-value-as-in-property.Get>\n	Get all the properties in one call. Each property is returned on a separate line and use the same value encoding as property.Get method, with an exception that newlines are encoded as literal \n and literal \ are encoded as \\.
admin.vm.property.GetDefault	vm	property	-	`type={str	int
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.CheckWithNetvm	vm	feature	-	value
admin.vm.feature.CheckWithAdminVM	vm	feature	-	value
admin.vm.feature.CheckWithTemplateAndAdminVM	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	-
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.ImportWithSize	vm	volume	<size_in_bytes>\n<raw volume data>	-	new version of admin.vm.volume.Import, allows new volume to be different size
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

Volume properties:

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

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