Right now, if you start a session via 'su' or 'sudo' from within a
session, we make sure to re-use the existing session instead of creating a
new one. We detect this by reading the session of the requesting PID.
However, with gnome-terminal running as a busname-unit, and as such
running outside the session of the user, this will no longer work.
Therefore, this patch makes sure to return the existing session of a VT if
you start a new one.
This has the side-effect, that you will re-use a session which your PID is
not part of. This works fine, but will break assumptions if the parent
session dies (and as such close your session even though you think you're
part of it). However, this should be perfectly fine. If you run multiple
logins on the same session, you should really know what you're doing. The
current way of silently accepting it but choosing the last registered
session is just weird.
Commit c0f32805 ("logind: use sd_event timer source for inhibitor
logic") reworked the main loop logic of logind so that it uses a
real timeout callback handler to execute delayed functions.
What the old code did, however, was to call those functions on
every iteration in the main loop, not only when the timeout
expired.
Restore that behavior by bringing back manager_dispatch_delayed(),
and call it from manager_run(). The internal event source callback
manager_inhibit_timeout_handler() was turned into a wrapper of
manager_dispatch_delayed() now.
Previously, we'd just count connected displays, and if there was 2 or
more we assumed a "docked" state.
With this change we now:
- Only count external displays, ignore internal ones (which we detect by
checking the connector name against a whitelist of known external plug
types)
- We ignore connectors which are explicitly disabled
- We then compare the count with >= 1 rather than >= 2 as before
This new logic has the benefit that systems that disconnect the internal
display when the lid is closed are better supported. Also, explicitly
disabled ports do not confuse the algorithm anymore.
This new algorithm has been suggested here:
http://lists.freedesktop.org/archives/intel-gfx/2015-June/068821.html
This also makes two functions static, that are not used outside of their
.c files.
When (for example) switching from X11 to a new VT and logging in there,
creating a new session, the user state file (/run/systemd/users/$uid) is
not updated after the session becomes active. The latest time it is
saved is when the session is in SESSION_OPENING.
This results in a /run/systemd/users/$uid file which contains
STATE=online for the current user on the current active VT, which is
obviously wrong.
As functions like sd_uid_get_state() use this file to get the user’s
state, this could result in things like PolicyKit making incorrect
decisions about the user’s state. (See
https://bugs.freedesktop.org/show_bug.cgi?id=76358.)
Fix this by re-saving the state for a session’s user after completing
the state_job for that session.
https://bugs.freedesktop.org/show_bug.cgi?id=90818
If NULL is specified for the bus it is now automatically derived from
the passed in message.
This commit also changes a number of invocations of sd_bus_send() to
make use of this.
This should simplify the prototype a bit. The bus parameter is redundant
in most cases, and in the few where it matters it can be derived from
the message via sd_bus_message_get_bus().
Port over more code from shutdownd and teach logind to write /run/nologin at
least 5 minutes before the system is going down, and
/run/systemd/shutdown/scheduled when a shutdown is scheduled.
Add a timer to print UTMP wall messages so that it repeatedly informs users
about a scheduled shutdown:
* every 1 minute with less than 10 minutes to go
* every 15 minutes with less than 60 minutes to go
* every 30 minutes with less than 180 minutes (3 hours) to go
* every 60 minutes if more than that to go
This functionality only active if the .EnableWallMessages DBus property
is set to true. Also, a custom string can be added to the wall message,
set through the WallMessagePrefix property.
Add a method called ScheduleShutdown in org.freedesktop.login1.Manager
which adds a timer to shut down the system at a later point in time.
The first argument holds the type of the schedule that is about to
happen, and must be one of 'reboot', 'halt' or 'poweroff'.
The second argument specifies the absolute time, based on
CLOCK_REALTIME in nanoseconds, at which the the operation should be
executed.
To cancel a previously scheduled shutdown, the CancelScheduledShutdown()
can be called, which returns a bool, indicating whether a scheduled
timeout was cancelled.
Also add a new property called ScheduledShutdown which returns the
equivalent to what was passed in via ScheduleShutdown, as '(st)' type.
Factor out the code to ask polkit for authorization from
method_do_shutdown_or_sleep() into an own function called
verify_shutdown_creds().
This is needed in order to also use the same checks when shutdown
operations are scheduled. For that, it's also necessary to allow
NULL values for that action{,_multiple_sessions,_ignore_inhibit)
arguments, which will suppress the call if no action string is
passed.
Instead of open-coding the delayed action and inhibit timeout logic,
switch over to a real sd_event_source based implementation.
This is not only easier to read but also allows us to add more timers
in the future.
Newer dbus versions have an "allow interactive authentication" bit in
the message header, hence it is not necessary to take a boolean for this
explicitly.
Interactive authorization should only happen asynchronously, hence
disallow it in synchronous bus_verify_polkit(), and rename it to
bus_test_polkit(). This way even if the bus message header asks for
interactive authorization, we'll ask for non-interactive authorization
which is actually the desired behaviour if CanSuspend, CanHibernate and
friends, which call this function.
This introduces 'HoldoffTimeoutSec' to logind.conf to make
IGNORE_LID_SWITCH_{SUSPEND,STARTUP}_USEC configurable.
Background: If an external monitor is connected, or if the system is
docked, we want to ignore LID events. This is required to support setups
where a laptop is used with external peripherals while the LID is closed.
However, this requires us to probe all hot-plugged devices before reacting
to LID events. But with modern buses like USB, the standards do not impose
any timeout on the slots, so we have no chance to know whether a given
slot is used or not. Hence, after resume and startup, we have to wait a
fixed timeout to give the kernel a chance to probe devices. Our timeout
has always been generous enough to support even the slowest devices.
However, a lot of people didn't use these features and wanted to disable
the hold-off timer. Now we provide a knob to do that.
This patch removes includes that are not used. The removals were found with
include-what-you-use which checks if any of the symbols from a header is
in use.
Also, allow clients to alter their own objects without any further
priviliges. i.e. this allows clients to kill and lock their own sessions
without involving PK.
After all it is now much more like strjoin() than strappend(). At the
same time, add support for NULL sentinels, even if they are normally not
necessary.
Whenever a process performs an action on an object, the kernel uses the
EUID of the process to do permission checks and to apply on any newly
created objects. The UID of a process is only used if someone *ELSE* acts
on the process. That is, the UID of a process defines who owns the
process, the EUID defines what privileges are used by this process when
performing an action.
Process limits, on the other hand, are always applied to the real UID, not
the effective UID. This is, because a process has a user object linked,
which always corresponds to its UID. A process never has a user object
linked for its EUID. Thus, accounting (and limits) is always done on the
real UID.
This commit fixes all sd-bus users to use the EUID when performing
privilege checks and alike. Furthermore, it fixes unix-creds to be parsed
as EUID, not UID (as the kernel always takes the EUID on UDS). Anyone
using UID (eg., to do user-accounting) has to fall back to the EUID as UDS
does not transmit the UID.
More specifically, if an operation is requested on a session with an
empty name, the caller's session is used. If an operation is requested
on a seat with an empty name, the seat of the caller's session is used.
Finally, if an operation on the user with UID -1 is requested, the user
of the client's session is used (and not the UID of the client!).
They do not use any functions from libcap directly. The CAP_* constants in use
through these files come from "missing.h" which will import <linux/capability.h>
and complement it with CAP_* constants not defined by the current kernel
headers. The "missing.h" header is imported through "util.h" which gets
imported in "logind.h".
Tested that "systemd-logind" builds cleanly and works after this change.
If the format string contains %m, clearly errno must have a meaningful
value, so we might as well use log_*_errno to have ERRNO= logged.
Using:
find . -name '*.[ch]' | xargs sed -r -i -e \
's/log_(debug|info|notice|warning|error|emergency)\((".*%m.*")/log_\1_errno(errno, \2/'
Plus some whitespace, linewrap, and indent adjustments.
First, let's drop the "bus" argument, we can determine it from the
message anyway.
Secondly, determine the right callback/userdata pair automatically from
what is currently is being dispatched. This should simplify things a lot
for us, since it makes it unnecessary to pass pointers through the
original handlers through all functions when we process messages, which
might require authentication.
This is a generalization of the vtable privilege check we already have,
but exported, and hence useful when preparing for a polkit change.
This will deal with the complexity that on dbus1 one cannot trust the
capability field we retrieve via the bus, since it is read via
/proc/$$/stat (and thus might be out-of-date) rather than directly from
the message (like on kdbus) or bus connection (as for uid creds on
dbus1).
Also, port over all code to this new API.
If the session already exists then the only way to log it is to set the
debug option of pam_systemd. There are no debug messages in the login
service that permits to log if the session already exists.
So just add it, and while we are it add the "uid" field to the debug
message that indicates that the session was created.
This is needed to give USB docking stations and suchlike time to settle,
so that a display connected to an USB docking station can actually act
as a lid swith inhibitor correctly.
With this change we should have somewhat reliable docking station
support in place.
Previously the returned object of constructor functions where sometimes
returned as last, sometimes as first and sometimes as second parameter.
Let's clean this up a bit. Here are the new rules:
1. The object the new object is derived from is put first, if there is any
2. The object we are creating will be returned in the next arguments
3. This is followed by any additional arguments
Rationale:
For functions that operate on an object we always put that object first.
Constructors should probably not be too different in this regard. Also,
if the additional parameters might want to use varargs which suggests to
put them last.
Note that this new scheme only applies to constructor functions, not to
all other functions. We do give a lot of freedom for those.
Note that this commit only changes the order of the new functions we
added, for old ones we accept the wrong order and leave it like that.
Otherwise we get a (harmless) message like:
systemd-logind[30845]: Failed to process message [type=signal sender=:1.36 path=/org/freedesktop/systemd1/job/4674 interface=org.freedesktop.DBus.Properties member=PropertiesChanged signature=sa{sv}as]: Invalid argument
The session_send_create_reply() function which notifies clients about
session creation is used for both session and user units. Unify the
shared code in a new function session_jobs_reply().
The session_save() will be called unconditionally on sessions since it
does not make sense to only call it if '!session->started', this will
also allow to update the session state as soon as possible.
Simplify the shutdown logic a bit:
- Keep the session FIFO around in the PAM module, even after the session
shutdown hook has been finished. This allows logind to track precisely
when the PAM handler goes away.
- In the ReleaseSession() call start a timer, that will stop terminate
the session when elapsed.
- Never fiddle with the KillMode of scopes to configure whether user
processes should be killed or not. Instead, simply leave the scope
units around when we terminate a session whose processes should not be
killed.
- When killing is enabled, stop the session scope on FIFO EOF or after
the ReleaseSession() timeout. When killing is disabled, simply tell
PID 1 to abandon the scope.
Because the scopes stay around and hence all processes are always member
of a scope, the system shutdown logic should be more robust, as the
scopes can be shutdown as part of the usual shutdown logic.
This is initialized from XDG_SESSION_DESKTOP and is useful for GNOME
to recognize its own sessions. It's supposed to be set to a short string
identifying the session, such as "kde" or "gnome".
Introduces a new concept of "trusted" vs. "untrusted" busses. For the
latter libsystemd-bus will automatically do per-method access control,
for the former all access is automatically granted. Per-method access
control is encoded in the vtables: by default all methods are only
accessible to privileged clients. If the SD_BUS_VTABLE_UNPRIVILEGED flag
is set for a method it is accessible to unprivileged clients too. By
default whether a client is privileged is determined via checking for
its CAP_SYS_ADMIN capability, but this can be altered via the
SD_BUS_VTABLE_CAPABILITY() macro that can be ORed into the flags field
of the method.
Writable properties are also subject to SD_BUS_VTABLE_UNPRIVILEGED and
SD_BUS_VTABLE_CAPABILITY() for controlling write access to them. Note
however that read access is unrestricted, as PropertiesChanged messages
might send out the values anyway as an unrestricted broadcast.
By default the system bus is set to "untrusted" and the user bus is
"trusted" since per-method access control on the latter is unnecessary.
On dbus1 busses we check the UID of the caller rather than the
configured capability since the capability cannot be determined without
race. On kdbus the capability is checked if possible from the attached
meta-data of a message and otherwise queried from the sending peer.
This also decorates the vtables of the various daemons we ship with
these flags.
This way we can unify handling of credentials that are attached to
messages, or can be queried for bus name owners or connection peers.
This also adds the ability to extend incomplete credential information
with data from /proc,
Also, provide a convenience call that will automatically determine the
most appropriate credential object for an incoming message, by using the
the attached information if possible, the sending name information if
available and otherwise the peer's credentials.
This field is always false, drop it. If you want a reliable way to get
session state, call session_get_state(). Testing for any flags directly
doesn't work currently so don't pretend it would.
Sessions on seat0 must pass us a vtnr, otherwise, you shouldn't try
attaching it to seat0. For seats without VTs, we do the exact opposite: we
forbid VTs.
There can be odd situations if the session-files contain invalid
combinations. However, we try to keep sessions alive and restore state as
good as possible.
Fix the whole code to use "unsigned int" for vtnr. 0 is an invalid vtnr so
we don't need negative numbers at all.
Note that most code already assumes it's unsigned so in case there's a
negative vtnr, our code may, under special circumstances, silently break.
So this patch makes sure all sources of vtnrs verify the validity. Also
note that the dbus api already uses unsigned ints.
It's better not to set any XDG_RUNTIME_DIR at all rather than one of a
different user. So let's do this.
This changes the bus call parameters of CreateSession(), but that is
explicitly an internal API hence should be fine. Note however, that a
logind restart (the way the RPM postinst scriptlets do it) is necessary
to make things work again.
Message handler callbacks can be simplified drastically if the
dispatcher automatically replies to method calls if errors are returned.
Thus: add an sd_bus_error argument to all message handlers. When we
dispatch a message handler and it returns negative or a set sd_bus_error
we send this as message error back to the client. This means errors
returned by handlers by default are given back to clients instead of
rippling all the way up to the event loop, which is desirable to make
things robust.
As a side-effect we can now easily turn the SELinux checks into normal
function calls, since the method call dispatcher will generate the right
error replies automatically now.
Also, make sure we always pass the error structure to all property and
method handlers as last argument to follow the usual style of passing
variables for return values as last argument.
This patch converts PID 1 to libsystemd-bus and thus drops the
dependency on libdbus. The only remaining code using libdbus is a test
case that validates our bus marshalling against libdbus' marshalling,
and this dependency can be turned off.
This patch also adds a couple of things to libsystem-bus, that are
necessary to make the port work:
- Synthesizing of "Disconnected" messages when bus connections are
severed.
- Support for attaching multiple vtables for the same interface on the
same path.
This patch also fixes the SetDefaultTarget() and GetDefaultTarget() bus
calls which used an inappropriate signature.
As a side effect we will now generate PropertiesChanged messages which
carry property contents, rather than just invalidation information.
Since the invention of read-only memory, write-only memory has been
considered deprecated. Where appropriate, either make use of the
value, or avoid writing it, to make it clear that it is not used.
We currently use seat_can_multi_session() to test for two things:
* whether the seat can handle session-switching
* whether the seat has VTs
As both are currently logically equivalent, we didn't care. However, we
want to allow session-switching on seats without VTs, so split this helper
into:
* seat_can_multi_session(): whether session-switching is supported
* seat_has_vts(): whether the seat has VTs
Note that only one seat on a system can have VTs. There is only one set of
them. We automatically assign them to seat0 as usual.
With this patch in place, we can easily add new session-switching/tracking
methods without breaking any VT code as it is now protected by has_vts(),
no longer by can_multi_session().
The seat->vtconsole member always points to the default seat seat0. Even
if VTs are disabled, it's used as default seat. Therefore, rename it to
seat0 to correctly state what it is.
This also changes the seat files in /run from IS_VTCONSOLE to IS_SEAT0. It
wasn't used by any code, yet, so this seems fine.
While we are at it, we also remove every "if (s->vtconsole)" as this
pointer is always valid!
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.
If we want to track bus-names to allow exclusive resource-access, we need
a way to get notified when a bus-name is gone. We make logind watch for
NameOwnerChanged dbus events and check whether the name is currently
watched. If it is, we remove it from the watch-list (notification for
other objects can be added in follow-up patches).
bash ignores SIGTERM, and can only be terminated cleanly via SIGHUP.
Hence make sure that we the scope unit for the session is created with
SendSIGHUP enabled.
As we want to centralized cgroup access we should stop killing the user
sessions directly from the systemd-user-sessions service. Instead, rely
on PID 1 doing this by adding the right ordering dependencies to the
session scope units.
When PID 1 reloads the units logind/machined will see UnitRemoved
signals for all units. Instead of trusting these immediately, let's
check the actual unit state before considering a unit gone, so that
reloading PID 1 is not mistaken as the end of all sessions.
