95 lines
3.6 KiB
ReStructuredText
95 lines
3.6 KiB
ReStructuredText
:py:mod:`qubes.policy` -- Qubes RPC policy
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==========================================
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Every Qubes domain can trigger various RPC services, but if such call would be
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allowed depends on Qubes RPC policy (qrexec policy in short).
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Qrexec policy format
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--------------------
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Policy consists of a file, which is parsed line-by-line. First matching line
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is used as an action.
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Each line consist of three values separated by white characters (space(s), tab(s)):
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1. Source specification, which is one of:
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- domain name
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- `$anyvm` - any domain
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- `$tag:some-tag` - VM having tag `some-tag`
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- `$type:vm-type` - VM of `vm-type` type, available types:
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AppVM, TemplateVM, StandaloneVM, DispVM
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2. Target specification, one of:
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- domain name
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- `$anyvm` - any domain, excluding dom0
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- `$tag:some-tag` - domain having tag `some-tag`
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- `$type:vm-type` - domain of `vm-type` type, available types:
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AppVM, TemplateVM, StandaloneVM, DispVM
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- `$default` - used when caller did not specified any VM
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- `$dispvm:vm-name` - _new_ Disposable VM created from AppVM `vm-name`
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- `$dispvm` - _new_ Disposable VM created from AppVM pointed by caller
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property `default_dispvm`, which defaults to global property `default_dispvm`
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- `$adminvm` - Admin VM aka dom0
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Dom0 can only be matched explicitly - either as `dom0` or `$adminvm` keyword.
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None of `$anyvm`, `$tag:some-tag`, `$type:AdminVM` will match.
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3. Action and optional action parameters, one of:
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- `allow` - allow the call, without further questions; optional parameters:
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- `target=` - override caller provided call target -
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possible values are: domain name, `$dispvm` or `$dispvm:vm-name`
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- `user=` - call the service using this user, instead of the user
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pointed by target VM's `default_user` property
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- `deny` - deny the call, without further questions; no optional
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parameters are supported
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- `ask` - ask the user for confirmation; optional parameters:
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- `target=` - override user provided call target
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- `user=` - call the service using this user, instead of the user
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pointed by target VM's `default_user` property
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- `default_target=` - suggest this target when prompting the user for
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confirmation
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Alternatively, a line may consist of a single keyword `$include:` followed by a
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path. This will load a given file as its content would be in place of
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`$include` line. Relative paths are resolved relative to
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`/etc/qubes-rpc/policy` directory.
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Evaluating `ask` action
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-----------------------
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When qrexec policy specify `ask` action, the user is asked whether the call
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should be allowed or denied. In addition to that, user also need to choose
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target domain. User have to choose from a set of targets specified by the
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policy. Such set is calculated using the algorithm below:
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1. If `ask` action have `target=` option specified, only that target is
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considered. A prompt window will allow to choose only this value and it will
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also be pre-filled value.
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2. If no `target=` option is specified, all rules are evaluated to see what
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target domains (for a given source domain) would result in `ask` or `allow`
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action. If any of them have `target=` option set, that value is used instead of
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the one specified in "target" column (for this particular line). Then the user
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is presented with a confirmation dialog and an option to choose from those
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domains.
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3. If `default_target=` option is set, it is used as
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suggested value, otherwise no suggestion is made (regardless of calling domain
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specified any target or not).
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Module contents
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---------------
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.. automodule:: qubespolicy
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:members:
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:show-inheritance:
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.. vim: ts=3 sw=3 et
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