man/sd_bus_creds_get_pid.xml

   1 <?xml version='1.0'?>
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
   5
   6 <refentry id="sd_bus_creds_get_pid" xmlns:xi="http://www.w3.org/2001/XInclude">
   7
   8   <refentryinfo>
   9     <title>sd_bus_creds_get_pid</title>
  10     <productname>systemd</productname>
  11   </refentryinfo>
  12
  13   <refmeta>
  14     <refentrytitle>sd_bus_creds_get_pid</refentrytitle>
  15     <manvolnum>3</manvolnum>
  16   </refmeta>
  17
  18   <refnamediv>
  19     <refname>sd_bus_creds_get_pid</refname>
  20     <refname>sd_bus_creds_get_ppid</refname>
  21     <refname>sd_bus_creds_get_tid</refname>
  22     <refname>sd_bus_creds_get_uid</refname>
  23     <refname>sd_bus_creds_get_euid</refname>
  24     <refname>sd_bus_creds_get_suid</refname>
  25     <refname>sd_bus_creds_get_fsuid</refname>
  26     <refname>sd_bus_creds_get_gid</refname>
  27     <refname>sd_bus_creds_get_egid</refname>
  28     <refname>sd_bus_creds_get_sgid</refname>
  29     <refname>sd_bus_creds_get_fsgid</refname>
  30     <refname>sd_bus_creds_get_supplementary_gids</refname>
  31     <refname>sd_bus_creds_get_comm</refname>
  32     <refname>sd_bus_creds_get_tid_comm</refname>
  33     <refname>sd_bus_creds_get_exe</refname>
  34     <refname>sd_bus_creds_get_cmdline</refname>
  35     <refname>sd_bus_creds_get_cgroup</refname>
  36     <refname>sd_bus_creds_get_unit</refname>
  37     <refname>sd_bus_creds_get_slice</refname>
  38     <refname>sd_bus_creds_get_user_unit</refname>
  39     <refname>sd_bus_creds_get_user_slice</refname>
  40     <refname>sd_bus_creds_get_session</refname>
  41     <refname>sd_bus_creds_get_owner_uid</refname>
  42     <refname>sd_bus_creds_has_effective_cap</refname>
  43     <refname>sd_bus_creds_has_permitted_cap</refname>
  44     <refname>sd_bus_creds_has_inheritable_cap</refname>
  45     <refname>sd_bus_creds_has_bounding_cap</refname>
  46     <refname>sd_bus_creds_get_selinux_context</refname>
  47     <refname>sd_bus_creds_get_audit_session_id</refname>
  48     <refname>sd_bus_creds_get_audit_login_uid</refname>
  49     <refname>sd_bus_creds_get_tty</refname>
  50     <refname>sd_bus_creds_get_unique_name</refname>
  51     <refname>sd_bus_creds_get_well_known_names</refname>
  52     <refname>sd_bus_creds_get_description</refname>
  53
  54     <refpurpose>Retrieve fields from a credentials object</refpurpose>
  55   </refnamediv>
  56
  57   <refsynopsisdiv>
  58     <funcsynopsis>
  59       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  60
  61       <funcprototype>
  62         <funcdef>int <function>sd_bus_creds_get_pid</function></funcdef>
  63         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  64         <paramdef>pid_t *<parameter>pid</parameter></paramdef>
  65       </funcprototype>
  66
  67       <funcprototype>
  68         <funcdef>int <function>sd_bus_creds_get_ppid</function></funcdef>
  69         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  70         <paramdef>pid_t *<parameter>ppid</parameter></paramdef>
  71       </funcprototype>
  72
  73       <funcprototype>
  74         <funcdef>int <function>sd_bus_creds_get_tid</function></funcdef>
  75         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  76         <paramdef>pid_t *<parameter>tid</parameter></paramdef>
  77       </funcprototype>
  78
  79       <funcprototype>
  80         <funcdef>int <function>sd_bus_creds_get_uid</function></funcdef>
  81         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  82         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
  83       </funcprototype>
  84
  85       <funcprototype>
  86         <funcdef>int <function>sd_bus_creds_get_euid</function></funcdef>
  87         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  88         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
  89       </funcprototype>
  90
  91       <funcprototype>
  92         <funcdef>int <function>sd_bus_creds_get_suid</function></funcdef>
  93         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  94         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
  95       </funcprototype>
  96
  97       <funcprototype>
  98         <funcdef>int <function>sd_bus_creds_get_fsuid</function></funcdef>
  99         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 100         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
 101       </funcprototype>
 102
 103       <funcprototype>
 104         <funcdef>int <function>sd_bus_creds_get_gid</function></funcdef>
 105         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 106         <paramdef>gid_t *<parameter>gid</parameter></paramdef>
 107       </funcprototype>
 108
 109       <funcprototype>
 110         <funcdef>int <function>sd_bus_creds_get_egid</function></funcdef>
 111         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 112         <paramdef>gid_t *<parameter>gid</parameter></paramdef>
 113       </funcprototype>
 114
 115       <funcprototype>
 116         <funcdef>int <function>sd_bus_creds_get_sgid</function></funcdef>
 117         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 118         <paramdef>gid_t *<parameter>gid</parameter></paramdef>
 119       </funcprototype>
 120
 121       <funcprototype>
 122         <funcdef>int <function>sd_bus_creds_get_fsgid</function></funcdef>
 123         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 124         <paramdef>gid_t *<parameter>gid</parameter></paramdef>
 125       </funcprototype>
 126
 127       <funcprototype>
 128         <funcdef>int <function>sd_bus_creds_get_supplementary_gids</function></funcdef>
 129         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 130         <paramdef>const gid_t **<parameter>gids</parameter></paramdef>
 131       </funcprototype>
 132
 133       <funcprototype>
 134         <funcdef>int <function>sd_bus_creds_get_comm</function></funcdef>
 135         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 136         <paramdef>const char **<parameter>comm</parameter></paramdef>
 137       </funcprototype>
 138
 139       <funcprototype>
 140         <funcdef>int <function>sd_bus_creds_get_tid_comm</function></funcdef>
 141         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 142         <paramdef>const char **<parameter>comm</parameter></paramdef>
 143       </funcprototype>
 144
 145       <funcprototype>
 146         <funcdef>int <function>sd_bus_creds_get_exe</function></funcdef>
 147         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 148         <paramdef>const char **<parameter>exe</parameter></paramdef>
 149       </funcprototype>
 150
 151       <funcprototype>
 152         <funcdef>int <function>sd_bus_creds_get_cmdline</function></funcdef>
 153         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 154         <paramdef>char ***<parameter>cmdline</parameter></paramdef>
 155       </funcprototype>
 156
 157       <funcprototype>
 158         <funcdef>int <function>sd_bus_creds_get_cgroup</function></funcdef>
 159         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 160         <paramdef>const char **<parameter>cgroup</parameter></paramdef>
 161       </funcprototype>
 162
 163       <funcprototype>
 164         <funcdef>int <function>sd_bus_creds_get_unit</function></funcdef>
 165         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 166         <paramdef>const char **<parameter>unit</parameter></paramdef>
 167       </funcprototype>
 168
 169       <funcprototype>
 170         <funcdef>int <function>sd_bus_creds_get_slice</function></funcdef>
 171         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 172         <paramdef>const char **<parameter>slice</parameter></paramdef>
 173       </funcprototype>
 174
 175       <funcprototype>
 176         <funcdef>int <function>sd_bus_creds_get_user_unit</function></funcdef>
 177         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 178         <paramdef>const char **<parameter>unit</parameter></paramdef>
 179       </funcprototype>
 180
 181       <funcprototype>
 182         <funcdef>int <function>sd_bus_creds_get_user_slice</function></funcdef>
 183         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 184         <paramdef>const char **<parameter>slice</parameter></paramdef>
 185       </funcprototype>
 186
 187       <funcprototype>
 188         <funcdef>int <function>sd_bus_creds_get_session</function></funcdef>
 189         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 190         <paramdef>const char **<parameter>slice</parameter></paramdef>
 191       </funcprototype>
 192
 193       <funcprototype>
 194         <funcdef>int <function>sd_bus_creds_get_owner_uid</function></funcdef>
 195         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 196         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
 197       </funcprototype>
 198
 199       <funcprototype>
 200         <funcdef>int <function>sd_bus_creds_has_effective_cap</function></funcdef>
 201         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 202         <paramdef>int <parameter>capability</parameter></paramdef>
 203       </funcprototype>
 204
 205       <funcprototype>
 206         <funcdef>int <function>sd_bus_creds_has_permitted_cap</function></funcdef>
 207         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 208         <paramdef>int <parameter>capability</parameter></paramdef>
 209       </funcprototype>
 210
 211       <funcprototype>
 212         <funcdef>int <function>sd_bus_creds_has_inheritable_cap</function></funcdef>
 213         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 214         <paramdef>int <parameter>capability</parameter></paramdef>
 215       </funcprototype>
 216
 217       <funcprototype>
 218         <funcdef>int <function>sd_bus_creds_has_bounding_cap</function></funcdef>
 219         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 220         <paramdef>int <parameter>capability</parameter></paramdef>
 221       </funcprototype>
 222
 223       <funcprototype>
 224         <funcdef>int <function>sd_bus_creds_get_selinux_context</function></funcdef>
 225         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 226         <paramdef>const char **<parameter>context</parameter></paramdef>
 227       </funcprototype>
 228
 229       <funcprototype>
 230         <funcdef>int <function>sd_bus_creds_get_audit_session_id</function></funcdef>
 231         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 232         <paramdef>uint32_t *<parameter>sessionid</parameter></paramdef>
 233       </funcprototype>
 234
 235       <funcprototype>
 236         <funcdef>int <function>sd_bus_creds_get_audit_login_uid</function></funcdef>
 237         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 238         <paramdef>uid_t *<parameter>loginuid</parameter></paramdef>
 239       </funcprototype>
 240
 241       <funcprototype>
 242         <funcdef>int <function>sd_bus_creds_get_tty</function></funcdef>
 243         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 244         <paramdef>const char **<parameter>tty</parameter></paramdef>
 245       </funcprototype>
 246
 247       <funcprototype>
 248         <funcdef>int <function>sd_bus_creds_get_unique_name</function></funcdef>
 249         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 250         <paramdef>const char **<parameter>name</parameter></paramdef>
 251       </funcprototype>
 252
 253       <funcprototype>
 254         <funcdef>int <function>sd_bus_creds_get_well_known_names</function></funcdef>
 255         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 256         <paramdef>char ***<parameter>name</parameter></paramdef>
 257       </funcprototype>
 258
 259       <funcprototype>
 260         <funcdef>int <function>sd_bus_creds_get_description</function></funcdef>
 261         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
 262         <paramdef>const char **<parameter>name</parameter></paramdef>
 263       </funcprototype>
 264
 265     </funcsynopsis>
 266   </refsynopsisdiv>
 267
 268   <refsect1>
 269     <title>Description</title>
 270
 271     <para>These functions return credential information from an
 272     <parameter>sd_bus_creds</parameter> object. Credential objects may
 273     be created with
 274     <citerefentry><refentrytitle>sd_bus_creds_new_from_pid</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 275     in which case they describe the credentials of the process
 276     identified by the specified PID, with
 277     <citerefentry><refentrytitle>sd_bus_get_name_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 278     in which case they describe the credentials of a bus peer
 279     identified by the specified bus name, with
 280     <citerefentry><refentrytitle>sd_bus_get_owner_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 281     in which case they describe the credentials of the creator of a
 282     bus, or with
 283     <citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 284     in which case they describe the credentials of the sender of the
 285     message.</para>
 286
 287     <para>Not all credential fields are part of every
 288     <literal>sd_bus_creds</literal> object. Use
 289     <citerefentry><refentrytitle>sd_bus_creds_get_mask</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 290     to determine the mask of fields available.</para>
 291
 292     <para><function>sd_bus_creds_get_pid()</function> will retrieve
 293     the PID (process identifier). Similarly,
 294     <function>sd_bus_creds_get_ppid()</function> will retrieve the
 295     parent PID. Note that PID 1 has no parent process, in which case
 296     -ENXIO is returned.</para>
 297
 298     <para><function>sd_bus_creds_get_tid()</function> will retrieve the
 299     TID (thread identifier).</para>
 300
 301     <para><function>sd_bus_creds_get_uid()</function> will retrieve
 302     the numeric UID (user identifier). Similarly,
 303     <function>sd_bus_creds_get_euid()</function> returns the effective
 304     UID, <function>sd_bus_creds_get_suid()</function> the saved UID
 305     and <function>sd_bus_creds_get_fsuid()</function> the file system
 306     UID.</para>
 307
 308     <para><function>sd_bus_creds_get_gid()</function> will retrieve the
 309     numeric GID (group identifier). Similarly,
 310     <function>sd_bus_creds_get_egid()</function> returns the effective
 311     GID, <function>sd_bus_creds_get_sgid()</function> the saved GID
 312     and <function>sd_bus_creds_get_fsgid()</function> the file system
 313     GID.</para>
 314
 315     <para><function>sd_bus_creds_get_supplementary_gids()</function>
 316     will retrieve the supplementary GIDs list.</para>
 317
 318     <para><function>sd_bus_creds_get_comm()</function> will retrieve the
 319     comm field (truncated name of the executable, as stored in
 320     <filename>/proc/<replaceable>pid</replaceable>/comm</filename>).
 321     </para>
 322
 323     <para><function>sd_bus_creds_get_tid_comm()</function> will retrieve
 324     the comm field of the thread (as stored in
 325     <filename>/proc/<replaceable>pid</replaceable>/task/<replaceable>tid</replaceable>/comm</filename>).
 326     </para>
 327
 328     <para><function>sd_bus_creds_get_exe()</function> will retrieve the path to the program executable (as
 329     stored in the <filename>/proc/<replaceable>pid</replaceable>/exe</filename> link, but with the <literal>
 330     (deleted)</literal> suffix removed). Note that kernel threads do not have an executable path, in which
 331     case -ENXIO is returned. Note that this property should not be used for more than explanatory
 332     information, in particular it should not be used for security-relevant decisions. That's because the
 333     executable might have been replaced or removed by the time the value can be processed. Moreover, the
 334     kernel exports this information in an ambiguous way (i.e. a deleted executable cannot be safely
 335     distinguished from one whose name suffix is <literal> (deleted)</literal>).</para>
 336
 337     <para><function>sd_bus_creds_get_cmdline()</function> will
 338     retrieve an array of command line arguments (as stored in
 339     <filename>/proc/<replaceable>pid</replaceable>/cmdline</filename>). Note
 340     that kernel threads do not have a command line, in which case
 341     -ENXIO is returned.</para>
 342
 343     <para><function>sd_bus_creds_get_cgroup()</function> will retrieve
 344     the control group path. See <ulink
 345     url="https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt">cgroups.txt</ulink>.
 346     </para>
 347
 348     <para><function>sd_bus_creds_get_unit()</function> will retrieve
 349     the systemd unit name (in the system instance of systemd) that the
 350     process is a part of. See
 351     <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. For
 352     processes that are not part of a unit, returns -ENXIO.
 353     </para>
 354
 355     <para><function>sd_bus_creds_get_user_unit()</function> will
 356     retrieve the systemd unit name (in the user instance of systemd)
 357     that the process is a part of. See
 358     <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. For
 359     processes that are not part of a user unit, returns -ENXIO.
 360     </para>
 361
 362     <para><function>sd_bus_creds_get_slice()</function> will retrieve
 363     the systemd slice (a unit in the system instance of systemd) that
 364     the process is a part of. See
 365     <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Similarly,
 366     <function>sd_bus_creds_get_user_slice()</function> retrieves the
 367     systemd slice of the process, in the user instance of systemd.
 368     </para>
 369
 370     <para><function>sd_bus_creds_get_session()</function> will
 371     retrieve the identifier of the login session that the process is
 372     a part of. Please note the login session may be limited to a stub
 373     process or two.  User processes may instead be started from their
 374     systemd user manager, e.g. GUI applications started using DBus
 375     activation, as well as service processes which are shared between
 376     multiple logins of the same user. For processes that are not part
 377     of a session, returns -ENXIO.</para>
 378
 379     <para><function>sd_bus_creds_get_owner_uid()</function> will
 380     retrieve the numeric UID (user identifier) of the user who owns
 381     the user unit or login session that the process is a part of. See
 382     <citerefentry><refentrytitle>systemd-logind.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
 383     For processes that are not part of a user unit or session, returns
 384     -ENXIO.
 385     </para>
 386
 387     <para><function>sd_bus_creds_has_effective_cap()</function> will check whether the capability specified by
 388     <parameter>capability</parameter> was set in the effective capabilities mask. A positive return value means that it
 389     was set, zero means that it was not set, and a negative return value indicates an error. See <citerefentry
 390     project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry> and the
 391     <varname>AmbientCapabilities=</varname> and <varname>CapabilityBoundingSet=</varname> settings in
 392     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 393     </para>
 394
 395     <para><function>sd_bus_creds_has_permitted_cap()</function> is
 396     similar to <function>sd_bus_creds_has_effective_cap()</function>,
 397     but will check the permitted capabilities mask.</para>
 398
 399     <para><function>sd_bus_creds_has_inheritable_cap()</function> is
 400     similar to <function>sd_bus_creds_has_effective_cap()</function>,
 401     but will check the inheritable capabilities mask.</para>
 402
 403     <para><function>sd_bus_creds_has_bounding_cap()</function> is
 404     similar to <function>sd_bus_creds_has_effective_cap()</function>,
 405     but will check the bounding capabilities mask.</para>
 406
 407     <para><function>sd_bus_creds_get_selinux_context()</function> will
 408     retrieve the SELinux security context (label) of the process.</para>
 409
 410     <para><function>sd_bus_creds_get_audit_session_id()</function>
 411     will retrieve the audit session identifier of the process. Returns
 412     -ENXIO for processes that are not part of an audit session.</para>
 413
 414     <para><function>sd_bus_creds_get_audit_login_uid()</function> will
 415     retrieve the audit user login identifier (the identifier of the
 416     user who is "responsible" for the session). Returns -ENXIO for
 417     processes that are not part of an audit session.</para>
 418
 419     <para><function>sd_bus_creds_get_tty()</function> will retrieve
 420     the controlling TTY, without the prefixing "/dev/". Returns -ENXIO
 421     for processes that have no controlling TTY.</para>
 422
 423     <para><function>sd_bus_creds_get_unique_name()</function> will
 424     retrieve the D-Bus unique name. See <ulink
 425     url="http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names-bus">The
 426     D-Bus specification</ulink>.</para>
 427
 428     <para><function>sd_bus_creds_get_well_known_names()</function> will
 429     retrieve the set of D-Bus well-known names. See <ulink
 430     url="http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names-bus">The
 431     D-Bus specification</ulink>.</para>
 432
 433     <para><function>sd_bus_creds_get_description()</function> will
 434     retrieve a descriptive name of the bus connection of the
 435     peer. This name is useful to discern multiple bus connections by
 436     the same peer, and may be altered by the peer with the
 437     <citerefentry><refentrytitle>sd_bus_set_description</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 438     call.</para>
 439
 440     <para>All functions that take a <parameter>const
 441     char**</parameter> parameter will store the answer there as an
 442     address of a NUL-terminated string. It will be valid as long as
 443     <parameter>c</parameter> remains valid, and should not be freed or
 444     modified by the caller.</para>
 445
 446     <para>All functions that take a <parameter>char***</parameter>
 447     parameter will store the answer there as an address of an array
 448     of strings. Each individual string is NUL-terminated, and the
 449     array is NULL-terminated as a whole. It will be valid as long as
 450     <parameter>c</parameter> remains valid, and should not be freed or
 451     modified by the caller.</para>
 452   </refsect1>
 453
 454   <refsect1>
 455     <title>Return Value</title>
 456
 457     <para>On success, these calls return 0 or a positive integer. On
 458     failure, these calls return a negative errno-style error code.
 459     </para>
 460
 461     <refsect2>
 462       <title>Errors</title>
 463
 464       <para>Returned errors may indicate the following problems:</para>
 465
 466       <variablelist>
 467         <varlistentry>
 468           <term><constant>-ENODATA</constant></term>
 469
 470           <listitem><para>The given field is not available in the credentials object
 471           <parameter>c</parameter>.</para>
 472           </listitem>
 473         </varlistentry>
 474
 475         <varlistentry>
 476           <term><constant>-ENXIO</constant></term>
 477
 478           <listitem><para>The given field is not specified for the described process or peer. This will be
 479           returned by <function>sd_bus_creds_get_unit()</function>,
 480           <function>sd_bus_creds_get_slice()</function>, <function>sd_bus_creds_get_user_unit()</function>,
 481           <function>sd_bus_creds_get_user_slice()</function>, and
 482           <function>sd_bus_creds_get_session()</function> if the process is not part of a systemd system
 483           unit, systemd user unit, systemd slice, or logind session. It will be returned by
 484           <function>sd_bus_creds_get_owner_uid()</function> if the process is not part of a systemd user unit
 485           or logind session. It will also be returned by <function>sd_bus_creds_get_exe()</function> and
 486           <function>sd_bus_creds_get_cmdline()</function> for kernel threads (since these are not started
 487           from an executable binary, nor have a command line), and by
 488           <function>sd_bus_creds_get_audit_session_id()</function> and
 489           <function>sd_bus_creds_get_audit_login_uid()</function> when the process is not part of an audit
 490           session, and <function>sd_bus_creds_get_tty()</function> if the process has no controlling
 491           TTY.</para></listitem>
 492         </varlistentry>
 493
 494         <varlistentry>
 495           <term><constant>-EINVAL</constant></term>
 496
 497           <listitem><para>Specified pointer parameter is <constant>NULL</constant>.</para></listitem>
 498         </varlistentry>
 499
 500         <varlistentry>
 501           <term><constant>-ENOMEM</constant></term>
 502
 503           <listitem><para>Memory allocation failed.</para></listitem>
 504         </varlistentry>
 505       </variablelist>
 506     </refsect2>
 507   </refsect1>
 508
 509   <xi:include href="libsystemd-pkgconfig.xml" />
 510
 511   <refsect1>
 512     <title>See Also</title>
 513
 514     <para>
 515       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 516       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 517       <citerefentry><refentrytitle>sd_bus_creds_new_from_pid</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
 518       <citerefentry project='man-pages'><refentrytitle>fork</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
 519       <citerefentry project='man-pages'><refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
 520       <citerefentry project='man-pages'><refentrytitle>credentials</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 521       <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 522       <citerefentry project='man-pages'><refentrytitle>proc</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 523       <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 524     </para>
 525   </refsect1>
 526
 527 </refentry>