Admin API

You may also be interested in the articleIntroducing the Qubes 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, unstable, and not yet documented.

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.

i
call	dest	argument	inside	return	note
`admin.vmclass.List`	`dom0`	-	-	`<class>`
`admin.vm.List`	`dom0\|<vm>`	-	-	`<name> class=<class> state=<state>`
`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>`
`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>`
`admin.property.Get`	`dom0`	property	-	`default={True\|False}` `type={str\|int\|bool\|vm\|label\|list} <value>`	Type `list` is added in R4.1. Values are of type `str` and each entry is suffixed with newline character.
`admin.property.GetAll`	`dom0`	-	-	`<property-name> <full-value-as-in-property.Get>`	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`	propety	-	`type={str\|int\|bool\|vm\|label\|list} <value>`	Type `list` is added in R4.1. Values are of type `str` and each entry is suffixed with newline character.
`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>`
`admin.vm.property.Get`	`vm`	property	-	`default={True\|False}` `type={str\|int\|bool\|vm\|label\|list} <value>`
`admin.vm.property.GetAll`	`vm`	-	-	`<property-name> <full-value-as-in-property.Get>`	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\|bool\|vm\|label\|type} <value>`	Type `list` is added in R4.1. Each list entry is suffixed with a newline character
`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>`
`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>`
`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>`	rules syntax as in firewall interface (Firewall Rules in 4x) with addition of `expire=` and `comment=` options; `comment=` (if present) must be the last option
`admin.vm.firewall.Set`	vm	-	`<rule>`	-	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>`	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>`	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>`
`admin.pool.ListDrivers`	`dom0`	-	-	`<pool-driver> <property> ...`	Properties allowed in `admin.pool.Add`
`admin.pool.Info`	`dom0`	pool	-	`<property>=<value>`
`admin.pool.Add`	`dom0`	driver	`<property>=<value>`	-
`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>`
`admin.pool.volume.Set.revisions_to_keep`	`dom0`	pool	`<vid> <value>`	-
`admin.pool.volume.ListSnapshots`	`dom0`	pool	vid	`<snapshot>`
`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> <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>`	`<volume>` is per-VM volume name (`root`, `private`, etc), `<vid>` is pool-unique volume id
`admin.vm.volume.Info`	vm	volume	-	`<property>=<value>`
`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> <raw volume data>`	-	new version of `admin.vm.volume.Import`, allows new volume to be different size
`admin.vm.volume.Clear`	vm	volume	-	-	clear contents of volume
`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.CurrentState`	vm	-	-	`<state-property>=<value>`	state properties: `power_state`, `mem`, `mem_static_max`, `cputime`
`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
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

Policy admin API

There is also an API to view and update Qubes RPC policy files in dom0. All of the following calls have dom0 as destination:

i
call	argument	inside	return
`policy.List` `policy.include.List`	-	-	`<name1>\n<name2>...`
`policy.Get` `policy.include.Get`	name	-	`<token>\n<content>`
`policy.Get` `policy.include.Get`	name	`<token>\n<content>`	-
`policy.Remove` `policy.include.Remove`	name	`<token>`	-

The policy.* calls refer to main policy files (/etc/qubes/policy.d/), and the policy.include.* calls refer to the include directory (/etc/qubes/policy.d/include/). The .policy extension for files in the main directory is always omitted.

The responses do not follow admin API protocol, but signal error using an exit code and a message on stdout.

The changes are validated before saving, so that the policy cannot end up in an invalid state (e.g. syntax error, missing include file).

In addition, there is a mechanism to prevent concurrent modifications of the policy files:

A *.Get call returns a file along with a token (currently implemented as a hash of the file).
When calling Replace or Remove, you need to include the current token as first line. If the token does not match, the modification will fail.
When adding a new file using Replace, pass new as token. This will ensure that the file does not exist before adding.
To skip the check, pass any as token.

TODO

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