1PAM_SYSTEMD(8) pam_systemd PAM_SYSTEMD(8)
2
6 pam_systemd - Register user sessions in the systemd login manager
7
9 pam_systemd.so
10
12 pam_systemd registers user sessions with the systemd login manager
13 systemd-logind.service(8), and hence the systemd control group
14 hierarchy.
15 On login, this module — in conjunction with systemd-logind.service —
17 ensures the following:
18 1. If it does not exist yet, the user runtime directory /run/user/$UID
20 is either created or mounted as new "tmpfs" file system with quota
21 applied, and its ownership changed to the user that is logging in.
22 2. The $XDG_SESSION_ID environment variable is initialized. If
24 auditing is available and pam_loginuid.so was run before this
25 module (which is highly recommended), the variable is initialized
26 from the auditing session id (/proc/self/sessionid). Otherwise, an
27 independent session counter is used.
28 3. A new systemd scope unit is created for the session. If this is the
30 first concurrent session of the user, an implicit per-user slice
31 unit below user.slice is automatically created and the scope placed
32 into it. An instance of the system service user@.service, which
33 runs the systemd user manager instance, is started.
34 On logout, this module ensures the following:
36 1. If enabled in logind.conf(5) (KillUserProcesses=), all processes of
38 the session are terminated. If the last concurrent session of a
39 user ends, the user's systemd instance will be terminated too, and
40 so will the user's slice unit.
41 2. If the last concurrent session of a user ends, the user runtime
43 directory /run/user/$UID and all its contents are removed, too.
44 If the system was not booted up with systemd as init system, this
46 module does nothing and immediately returns PAM_SUCCESS.
47
49 The following options are understood:
50 class=
52 Takes a string argument which sets the session class. The
53 XDG_SESSION_CLASS environmental variable takes precedence. One of
54 "user", "greeter", "lock-screen" or "background". See
55 sd_session_get_class(3) for details about the session class.
56 type=
58 Takes a string argument which sets the session type. The
59 XDG_SESSION_TYPE environmental variable takes precedence. One of
60 "unspecified", "tty", "x11", "wayland" or "mir". See
61 sd_session_get_type(3) for details about the session type.
62 debug[=]
64 Takes an optional boolean argument. If yes or without the argument,
65 the module will log debugging information as it operates.
66
68 Only session is provided.
69
71 The following environment variables are set for the processes of the
72 user's session:
73 $XDG_SESSION_ID
75 A session identifier, suitable to be used in filenames. The string
76 itself should be considered opaque, although often it is just the
77 audit session ID as reported by /proc/self/sessionid. Each ID will
78 be assigned only once during machine uptime. It may hence be used
79 to uniquely label files or other resources of this session.
80 $XDG_RUNTIME_DIR
82 Path to a user-private user-writable directory that is bound to the
83 user login time on the machine. It is automatically created the
84 first time a user logs in and removed on the user's final logout.
85 If a user logs in twice at the same time, both sessions will see
86 the same $XDG_RUNTIME_DIR and the same contents. If a user logs in
87 once, then logs out again, and logs in again, the directory
88 contents will have been lost in between, but applications should
89 not rely on this behavior and must be able to deal with stale
90 files. To store session-private data in this directory, the user
91 should include the value of $XDG_SESSION_ID in the filename. This
92 directory shall be used for runtime file system objects such as
93 AF_UNIX sockets, FIFOs, PID files and similar. It is guaranteed
94 that this directory is local and offers the greatest possible file
95 system feature set the operating system provides. For further
96 details, see the XDG Base Directory Specification[1].
97 $XDG_RUNTIME_DIR is not set if the current user is not the original
98 user of the session.
99 The following environment variables are read by the module and may be
101 used by the PAM service to pass metadata to the module:
102 $XDG_SESSION_TYPE
104 The session type. This may be used instead of session= on the
105 module parameter line, and is usually preferred.
106 $XDG_SESSION_CLASS
108 The session class. This may be used instead of class= on the module
109 parameter line, and is usually preferred.
110 $XDG_SESSION_DESKTOP
112 A single, short identifier string for the desktop environment. This
113 may be used to indicate the session desktop used, where this
114 applies and if this information is available. For example: "GNOME",
115 or "KDE". It is recommended to use the same identifiers and
116 capitalization as for $XDG_CURRENT_DESKTOP, as defined by the
117 Desktop Entry Specification[2]. (However, note that
118 $XDG_SESSION_DESKTOP only takes a single item, and not a
119 colon-separated list like $XDG_CURRENT_DESKTOP.) See
120 sd_session_get_desktop(3) for more details.
121 $XDG_SEAT
123 The seat name the session shall be registered for, if any.
124 $XDG_VTNR
126 The VT number the session shall be registered for, if any. (Only
127 applies to seats with a VT available, such as "seat0")
128 If not set, pam_systemd will determine the values for $XDG_SEAT and
130 $XDG_VTNR based on the $DISPLAY variable.
131
133 PAM modules earlier in the stack, that is those that come before
134 pam_systemd.so, can set session scope limits using the PAM context
135 objects. The data for these objects is provided as NUL-terminated C
136 strings and maps directly to the respective unit resource control
137 directives. Note that these limits apply to individual sessions of the
138 user, they do not apply to all user processes as a combined whole. In
139 particular, the per-user user@.service unit instance, which runs the
140 systemd --user manager process and its children, and is tracked outside
141 of any session, being shared by all the user's sessions, is not covered
142 by these limits.
143 See systemd.resource-control(5) for more information about the
145 resources. Also, see pam_set_data(3) for additional information about
146 how to set the context objects.
147 systemd.memory_max
149 Sets unit MemoryMax=.
150 systemd.tasks_max
152 Sets unit TasksMax=.
153 systemd.cpu_weight
155 Sets unit CPUWeight=.
156 systemd.io_weight
158 Sets unit IOWeight=.
159 Example data as can be provided from an another PAM module:
161 pam_set_data(handle, "systemd.memory_max", (void *)"200M", cleanup);
163 pam_set_data(handle, "systemd.tasks_max", (void *)"50", cleanup);
164 pam_set_data(handle, "systemd.cpu_weight", (void *)"100", cleanup);
165 pam_set_data(handle, "systemd.io_weight", (void *)"340", cleanup);
166
170 #%PAM-1.0
171 auth required pam_unix.so
172 auth required pam_nologin.so
173 account required pam_unix.so
174 password required pam_unix.so
175 session required pam_unix.so
176 session required pam_loginuid.so
177 session required pam_systemd.so
178
180 systemd(1), systemd-logind.service(8), logind.conf(5), loginctl(1),
181 pam.conf(5), pam.d(5), pam(8), pam_loginuid(8), systemd.scope(5),
182 systemd.slice(5), systemd.service(5)
183
185 1. XDG Base Directory Specification
186 http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
187 2. Desktop Entry Specification
189 http://standards.freedesktop.org/desktop-entry-spec/latest/
190systemd 239 PAM_SYSTEMD(8)