NAME
pam_systemd - Register user sessions in the systemd login managerSYNOPSIS
pam_systemd.soDESCRIPTION
pam_systemd registers user sessions with the systemd login manager systemd-logind.service(8), and hence the systemd control group hierarchy. The module also applies various resource management and runtime parameters to the new session, as configured in the JSON User Records[1] of the user, when one is defined. On login, this module — in conjunction with systemd-logind.service — ensures the following: 1.If it does not exist yet, the user runtime
directory /run/user/$UID is either created or mounted as new "tmpfs"
file system with quota applied, and its ownership changed to the user that is
logging in.
2.The $XDG_SESSION_ID environment
variable is initialized. If auditing is available and pam_loginuid.so
was run before this module (which is highly recommended), the variable is
initialized from the auditing session id (/proc/self/sessionid). Otherwise, an
independent session counter is used.
3.A new systemd scope unit is created for the
session. If this is the first concurrent session of the user, an implicit
per-user slice unit below user.slice is automatically created and the scope
placed into it. An instance of the system service [email protected], which runs
the systemd user manager instance, is started.
4.The "$TZ", "$EMAIL" and
"$LANG" environment variables are configured for the user, based on
the respective data from the user's JSON record (if it is defined). Moreover,
any environment variables explicitly configured in the user record are
imported, and the umask, nice level, and resource limits initialized.
On logout, this module ensures the following:
1.If enabled in logind.conf(5) (
KillUserProcesses=), all processes of the session are terminated. If
the last concurrent session of a user ends, the user's systemd instance will
be terminated too, and so will the user's slice unit.
2.If the last concurrent session of a user
ends, the user runtime directory /run/user/$UID and all its contents are
removed, too.
If the system was not booted up with systemd as init system, this module does
nothing and immediately returns PAM_SUCCESS.
OPTIONS
The following options are understood: class=Takes a string argument which sets the session
class. The XDG_SESSION_CLASS environment variable (see below) takes
precedence. One of "user", "greeter",
"lock-screen" or "background". See
sd_session_get_class(3) for details about the session class.
type=
Takes a string argument which sets the session
type. The XDG_SESSION_TYPE environment variable (see below) takes
precedence. One of "unspecified", "tty", "x11",
"wayland" or "mir". See sd_session_get_type(3) for
details about the session type.
desktop=
Takes a single, short identifier string for
the desktop environment. The XDG_SESSION_DESKTOP environment variable
(see below) takes precedence. This may be used to indicate the session desktop
used, where this applies and if this information is available. For example:
"GNOME", or "KDE". It is recommended to use the same
identifiers and capitalization as for $XDG_CURRENT_DESKTOP, as defined
by the Desktop Entry Specification[2]. (However, note that the option
only takes a single item, and not a colon-separated list like
$XDG_CURRENT_DESKTOP.) See sd_session_get_desktop(3) for further
details.
debug[=]
Takes an optional boolean argument. If yes or
without the argument, the module will log debugging information as it
operates.
MODULE TYPES PROVIDED
Only session is provided.ENVIRONMENT
The following environment variables are initialized by the module and available to the processes of the user's session: $XDG_SESSION_IDA short session identifier, suitable to be
used in filenames. The string itself should be considered opaque, although
often it is just the audit session ID as reported by /proc/self/sessionid.
Each ID will be assigned only once during machine uptime. It may hence be used
to uniquely label files or other resources of this session. Combine this ID
with the boot identifier, as returned by sd_id128_get_boot(3), for a
globally unique identifier.
$XDG_RUNTIME_DIR
Path to a user-private user-writable directory
that is bound to the user login time on the machine. It is automatically
created the first time a user logs in and removed on the user's final logout.
If a user logs in twice at the same time, both sessions will see the same
$XDG_RUNTIME_DIR and the same contents. If a user logs in once, then
logs out again, and logs in again, the directory contents will have been lost
in between, but applications should not rely on this behavior and must be able
to deal with stale files. To store session-private data in this directory, the
user should include the value of $XDG_SESSION_ID in the filename. This
directory shall be used for runtime file system objects such as AF_UNIX
sockets, FIFOs, PID files and similar. It is guaranteed that this directory is
local and offers the greatest possible file system feature set the operating
system provides. For further details, see the XDG Base Directory
Specification[3]. $XDG_RUNTIME_DIR is not set if the current user
is not the original user of the session.
$TZ, $EMAIL, $LANG
If a JSON user record is known for the user
logging in these variables are initialized from the respective data in the
record.
The following environment variables are read by the module and may be used by
the PAM service to pass metadata to the module. If these variables are not set
when the PAM module is invoked but can be determined otherwise they are set by
the module, so that these variables are initialized for the session and
applications if known at all.
$XDG_SESSION_TYPE
The session type. This may be used instead of
type= on the module parameter line, and is usually preferred.
$XDG_SESSION_CLASS
The session class. This may be used instead of
class= on the module parameter line, and is usually preferred.
$XDG_SESSION_DESKTOP
The desktop identifier. This may be used
instead of desktop= on the module parameter line, and is usually
preferred.
$XDG_SEAT
The seat name the session shall be registered
for, if any.
$XDG_VTNR
The VT number the session shall be registered
for, if any. (Only applies to seats with a VT available, such as
"seat0")
If not set, pam_systemd will initialize $XDG_SEAT and
$XDG_VTNR based on the $DISPLAY variable (if the latter is set).
SESSION LIMITS
PAM modules earlier in the stack, that is those that come before pam_systemd.so, can set session scope limits using the PAM context objects. The data for these objects is provided as NUL-terminated C strings and maps directly to the respective unit resource control directives. Note that these limits apply to individual sessions of the user, they do not apply to all user processes as a combined whole. In particular, the per-user [email protected] unit instance, which runs the systemd --user manager process and its children, and is tracked outside of any session, being shared by all the user's sessions, is not covered by these limits. See systemd.resource-control(5) for more information about the resources. Also, see pam_set_data(3) for additional information about how to set the context objects. systemd.memory_max=Sets unit MemoryMax=.
systemd.tasks_max=
Sets unit TasksMax=.
systemd.cpu_weight=
Sets unit CPUWeight=.
systemd.io_weight=
Sets unit IOWeight=.
systemd.runtime_max_sec=
Sets unit RuntimeMaxSec=.
Example data as can be provided from an another PAM module:
pam_set_data(handle, "systemd.memory_max", (void *)"200M", cleanup); pam_set_data(handle, "systemd.tasks_max", (void *)"50", cleanup); pam_set_data(handle, "systemd.cpu_weight", (void *)"100", cleanup); pam_set_data(handle, "systemd.io_weight", (void *)"340", cleanup); pam_set_data(handle, "systemd.runtime_max_sec", (void *)"3600", cleanup);
EXAMPLE
Here's an example PAM configuration fragment that allows users sessions to be managed by systemd-logind.service:#%PAM-1.0 auth sufficient pam_unix.so -auth sufficient pam_systemd_home.so auth required pam_deny.so account required pam_nologin.so -account sufficient pam_systemd_home.so account sufficient pam_unix.so account required pam_permit.so -password sufficient pam_systemd_home.so password sufficient pam_unix.so sha512 shadow try_first_pass password required pam_deny.so -session optional pam_keyinit.so revoke -session optional pam_loginuid.so -session optional pam_systemd_home.so -session optional pam_systemd.so session required pam_unix.so
SEE ALSO
systemd(1), systemd-logind.service(8), logind.conf(5), loginctl(1), pam_systemd_home(8), pam.conf(5), pam.d(5), pam(8), pam_loginuid(8), systemd.scope(5), systemd.slice(5), systemd.service(5)NOTES
- 1.
- JSON User Records
- 2.
- Desktop Entry Specification
- 3.
- XDG Base Directory Specification
systemd 252 |