summaryrefslogtreecommitdiff
path: root/src/login/logind-session.h
AgeCommit message (Collapse)Author
2013-11-05logind: port logind to libsystemd-busLennart Poettering
2013-09-17logind: introduce session-devicesDavid Herrmann
A session-device is a device that is bound to a seat and used by a session-controller to run the session. This currently includes DRM, fbdev and evdev devices. A session-device can be created via RequestDevice() on the dbus API of the session. You can drop it via ReleaseDevice() again. Once the session is destroyed or you drop control of the session, all session-devices are automatically destroyed. Session devices follow the session "active" state. A device can be active/running or inactive/paused. Whenever a session is not the active session, no session-device of it can be active. That is, if a session is not in foreground, all session-devices are paused. Whenever a session becomes active, all devices are resumed/activated by logind. If it fails, a device may stay paused. With every session-device you request, you also get a file-descriptor back. logind keeps a copy of this fd and uses kernel specific calls to pause/resume the file-descriptors. For example, a DRM fd is muted by logind as long as a given session is not active. Hence, the fd of the application is also muted. Once the session gets active, logind unmutes the fd and the application will get DRM access again. This, however, requires kernel support. DRM devices provide DRM-Master for synchronization, evdev devices have EVIOCREVOKE (pending on linux-input-ML). fbdev devices do not provide such synchronization methods (and never will). Note that for evdev devices, we call EVIOCREVOKE once a session gets inactive. However, this cannot be undone (the fd is still valid but mostly unusable). So we reopen a new fd once the session is activated and send it together with the ResumeDevice() signal. With this infrastructure in place, compositors can now run without CAP_SYS_ADMIN (that is, without being root). They use RequestControl() to acquire a session and listen for devices via udev_monitor. For every device they want to open, they call RequestDevice() on logind. This returns a fd which they can use now. They no longer have to open the devices themselves or call any privileged ioctls. This is all done by logind. Session-switches are still bound to VTs. Hence, compositors will get notified via the usual VT mechanisms and can cleanup their state. Once the VT switch is acknowledged as usual, logind will get notified via sysfs and pause the old-session's devices and resume the devices of the new session. To allow using this infrastructure with systems without VTs, we provide notification signals. logind sends PauseDevice("force") dbus signals to the current session controller for every device that it pauses. And it sends ResumeDevice signals for every device that it resumes. For seats with VTs this is sent _after_ the VT switch is acknowledged. Because the compositor already acknowledged that it cleaned-up all devices. However, for seats without VTs, this is used to notify the active compositor that the session is about to be deactivated. That is, logind sends PauseDevice("force") for each active device and then performs the session-switch. The session-switch changes the "Active" property of the session which can be monitored by the compositor. The new session is activated and the ResumeDevice events are sent. For seats without VTs, this is a forced session-switch. As this is not backwards-compatible (xserver actually crashes, weston drops the related devices, ..) we also provide an acknowledged session-switch. Note that this is never used for sessions with VTs. You use the acknowledged VT-switch on these seats. An acknowledged session switch sends PauseDevice("pause") instead of PauseDevice("force") to the active session. It schedules a short timeout and waits for the session to acknowledge each of them with PauseDeviceComplete(). Once all are acknowledged, or the session ran out of time, a PauseDevice("force") is sent for all remaining active devices and the session switch is performed. Note that this is only partially implemented, yet, as we don't allow multi-session without VTs, yet. A follow up commit will hook it up and implemented the acknowledgements+timeout. The implementation is quite simple. We use major/minor exclusively to identify devices on the bus. On RequestDevice() we retrieve the udev_device from the major/minor and search for an existing "Device" object. If no exists, we create it. This guarantees us that we are notified whenever the device changes seats or is removed. We create a new SessionDevice object and link it to the related Session and Device. Session->devices is a hashtable to lookup SessionDevice objects via major/minor. Device->session_devices is a linked list so we can release all linked session-devices once a device vanishes. Now we only have to hook this up in seat_set_active() so we correctly change device states during session-switches. As mentioned earlier, these are forced state-changes as VTs are currently used exclusively for multi-session implementations. Everything else are hooks to release all session-devices once the controller changes or a session is closed or removed.
2013-09-17logind: add session controllersDavid Herrmann
A session usually has only a single compositor or other application that controls graphics and input devices on it. To avoid multiple applications from hijacking each other's devices or even using the devices in parallel, we add session controllers. A session controller is an application that manages a session. Specific API calls may be limited to controllers to avoid others from getting unprivileged access to restricted resources. A session becomes a controller by calling the RequestControl() dbus API call. It can drop it via ReleaseControl(). logind tracks bus-names to release the controller once an application closes the bus. We use the new bus-name tracking to do that. Note that during ReleaseControl() we need to check whether some other session also tracks the name before we remove it from the bus-name tracking list. Currently, we only allow one controller at a time. However, the public API does not enforce this restriction. So if it makes sense, we can allow multiple controllers in parallel later. Or we can add a "scope" parameter, which allows a different controller for graphics-devices, sound-devices and whatever you want. Note that currently you get -EBUSY if there is already a controller. You can force the RequestControl() call (root-only) to drop the current controller and recover the session during an emergency. To recover a seat, this is not needed, though. You can simply create a new session or force-activate it. To become a session controller, a dbus caller must either be root or the same user as the user of the session. This allows us to run a session compositor as user and we no longer need any CAP_SYS_ADMIN.
2013-09-16Verify validity of session name when received from outsideZbigniew Jędrzejewski-Szmek
Only ASCII letters and digits are allowed.
2013-08-13logind: restore logic to kill user processes when session endsLennart Poettering
2013-07-02logind: port over to use scopes+slices for all cgroup stuffLennart Poettering
In order to prepare things for the single-writer cgroup scheme, let's make logind use systemd's own primitives for cgroup management. Every login user now gets his own private slice unit, in which his sessions live in a scope unit each. Also, add user@$UID.service to the same slice, and implicitly start it on first login.
2013-06-20logind: add infrastructure to keep track of machines, and move to slicesLennart Poettering
- This changes all logind cgroup objects to use slice objects rather than fixed croup locations. - logind can now collect minimal information about running VMs/containers. As fixed cgroup locations can no longer be used we need an entity that keeps track of machine cgroups in whatever slice they might be located. Since logind already keeps track of users, sessions and seats this is a trivial addition. - nspawn will now register with logind and pass various bits of metadata along. A new option "--slice=" has been added to place the container in a specific slice. - loginctl gained commands to list, introspect and terminate machines. - user.slice and machine.slice will now be pulled in by logind.service, since only logind.service requires this slice.
2013-05-02Add __attribute__((const, pure, format)) in various placesZbigniew Jędrzejewski-Szmek
I'm assuming that it's fine if a _const_ or _pure_ function calls assert. It is assumed that the assert won't trigger, and even if it does, it can only trigger on the first call with a given set of parameters, and we don't care if the compiler moves the order of calls.
2013-04-09logind: introduce an explicit session class for cronjobs and similarLennart Poettering
cronjobs are neither interactive user session, nor lock screens, nor login screens, hence they should get their own class.
2012-10-30logind: unify all session lock loopLennart Poettering
2012-07-19use #pragma once instead of foo*foo #define guardsShawn Landden
#pragma once has been "un-deprecated" in gcc since 3.3, and is widely supported in other compilers. I've been using and maintaining (rebasing) this patch for a while now, as it annoyed me to see #ifndef fooblahfoo, etc all over the place, almost arrogant about the annoyance of having to define all these names to perform a commen but neccicary functionality, when a completely superior alternative exists. I havn't sent it till now, cause its kindof a style change, and it is bad voodoo to mess with style that has been established by more established editors. So feel free to lambast me as a crazy bafoon. v2 - preserve externally used headers
2012-06-21logind: introduce a state for session, being one of online, active, closingLennart Poettering
online = logged in active = logged in and session is in the fg closing = nominally logged out but some left-over processes still around Related to: https://bugzilla.gnome.org/show_bug.cgi?id=677556
2012-04-12relicense to LGPLv2.1 (with exceptions)Lennart Poettering
We finally got the OK from all contributors with non-trivial commits to relicense systemd from GPL2+ to LGPL2.1+. Some udev bits continue to be GPL2+ for now, but we are looking into relicensing them too, to allow free copy/paste of all code within systemd. The bits that used to be MIT continue to be MIT. The big benefit of the relicensing is that closed source code may now link against libsystemd-login.so and friends.
2012-02-14login: track login class (i.e. one of "user", "greeter", "lock-screen") for ↵Lennart Poettering
each session This introduces the new PAM environment variable XDG_SESSION_CLASS. If not set, defaults to "user". This is useful for apps that want to distuingish real user logins from "fake" ones which just exist to show a gdm login screen or a lock screen.
2011-12-31logind: move logind into its own subdirectoryLennart Poettering