man/sd_pid_get_owner_uid.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-or-later -->
   5
   6 <refentry id="sd_pid_get_owner_uid" conditional='HAVE_PAM'
   7           xmlns:xi="http://www.w3.org/2001/XInclude">
   8
   9   <refentryinfo>
  10     <title>sd_pid_get_owner_uid</title>
  11     <productname>systemd</productname>
  12   </refentryinfo>
  13
  14   <refmeta>
  15     <refentrytitle>sd_pid_get_owner_uid</refentrytitle>
  16     <manvolnum>3</manvolnum>
  17   </refmeta>
  18
  19   <refnamediv>
  20     <refname>sd_pid_get_owner_uid</refname>
  21     <refname>sd_pid_get_session</refname>
  22     <refname>sd_pid_get_user_unit</refname>
  23     <refname>sd_pid_get_unit</refname>
  24     <refname>sd_pid_get_machine_name</refname>
  25     <refname>sd_pid_get_slice</refname>
  26     <refname>sd_pid_get_user_slice</refname>
  27     <refname>sd_pid_get_cgroup</refname>
  28     <refname>sd_peer_get_owner_uid</refname>
  29     <refname>sd_peer_get_session</refname>
  30     <refname>sd_peer_get_user_unit</refname>
  31     <refname>sd_peer_get_unit</refname>
  32     <refname>sd_peer_get_machine_name</refname>
  33     <refname>sd_peer_get_slice</refname>
  34     <refname>sd_peer_get_user_slice</refname>
  35     <refname>sd_peer_get_cgroup</refname>
  36     <refpurpose>Determine the owner uid of the user unit or session,
  37     or the session, user unit, system unit, container/VM or slice that
  38     a specific PID or socket peer belongs to</refpurpose>
  39   </refnamediv>
  40
  41   <refsynopsisdiv>
  42     <funcsynopsis>
  43       <funcsynopsisinfo>#include &lt;systemd/sd-login.h&gt;</funcsynopsisinfo>
  44
  45       <funcprototype>
  46         <funcdef>int <function>sd_pid_get_owner_uid</function></funcdef>
  47         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  48         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
  49       </funcprototype>
  50
  51       <funcprototype>
  52         <funcdef>int <function>sd_pid_get_session</function></funcdef>
  53         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  54         <paramdef>char **<parameter>session</parameter></paramdef>
  55       </funcprototype>
  56
  57       <funcprototype>
  58         <funcdef>int <function>sd_pid_get_user_unit</function></funcdef>
  59         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  60         <paramdef>char **<parameter>unit</parameter></paramdef>
  61       </funcprototype>
  62
  63       <funcprototype>
  64         <funcdef>int <function>sd_pid_get_unit</function></funcdef>
  65         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  66         <paramdef>char **<parameter>unit</parameter></paramdef>
  67       </funcprototype>
  68
  69       <funcprototype>
  70         <funcdef>int <function>sd_pid_get_machine_name</function></funcdef>
  71         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  72         <paramdef>char **<parameter>name</parameter></paramdef>
  73       </funcprototype>
  74
  75       <funcprototype>
  76         <funcdef>int <function>sd_pid_get_slice</function></funcdef>
  77         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  78         <paramdef>char **<parameter>slice</parameter></paramdef>
  79       </funcprototype>
  80
  81       <funcprototype>
  82         <funcdef>int <function>sd_pid_get_user_slice</function></funcdef>
  83         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  84         <paramdef>char **<parameter>slice</parameter></paramdef>
  85       </funcprototype>
  86
  87       <funcprototype>
  88         <funcdef>int <function>sd_pid_get_cgroup</function></funcdef>
  89         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  90         <paramdef>char **<parameter>cgroup</parameter></paramdef>
  91       </funcprototype>
  92
  93       <funcprototype>
  94         <funcdef>int <function>sd_peer_get_owner_uid</function></funcdef>
  95         <paramdef>int <parameter>fd</parameter></paramdef>
  96         <paramdef>uid_t *<parameter>uid</parameter></paramdef>
  97       </funcprototype>
  98
  99       <funcprototype>
 100         <funcdef>int <function>sd_peer_get_session</function></funcdef>
 101         <paramdef>int <parameter>fd</parameter></paramdef>
 102         <paramdef>char **<parameter>session</parameter></paramdef>
 103       </funcprototype>
 104
 105       <funcprototype>
 106         <funcdef>int <function>sd_peer_get_user_unit</function></funcdef>
 107         <paramdef>int <parameter>fd</parameter></paramdef>
 108         <paramdef>char **<parameter>unit</parameter></paramdef>
 109       </funcprototype>
 110
 111       <funcprototype>
 112         <funcdef>int <function>sd_peer_get_unit</function></funcdef>
 113         <paramdef>int <parameter>fd</parameter></paramdef>
 114         <paramdef>char **<parameter>unit</parameter></paramdef>
 115       </funcprototype>
 116
 117       <funcprototype>
 118         <funcdef>int <function>sd_peer_get_machine_name</function></funcdef>
 119         <paramdef>int <parameter>fd</parameter></paramdef>
 120         <paramdef>char **<parameter>name</parameter></paramdef>
 121       </funcprototype>
 122
 123       <funcprototype>
 124         <funcdef>int <function>sd_peer_get_slice</function></funcdef>
 125         <paramdef>int <parameter>fd</parameter></paramdef>
 126         <paramdef>char **<parameter>slice</parameter></paramdef>
 127       </funcprototype>
 128
 129       <funcprototype>
 130         <funcdef>int <function>sd_peer_get_user_slice</function></funcdef>
 131         <paramdef>int <parameter>fd</parameter></paramdef>
 132         <paramdef>char **<parameter>slice</parameter></paramdef>
 133       </funcprototype>
 134
 135       <funcprototype>
 136         <funcdef>int <function>sd_peer_get_cgroup</function></funcdef>
 137         <paramdef>int <parameter>fd</parameter></paramdef>
 138         <paramdef>char **<parameter>cgroup</parameter></paramdef>
 139       </funcprototype>
 140     </funcsynopsis>
 141   </refsynopsisdiv>
 142
 143   <refsect1>
 144     <title>Description</title>
 145
 146     <para><function>sd_pid_get_owner_uid()</function> may be used to
 147     determine the Unix UID (user identifier) which owns the login
 148     session or systemd user unit of a process identified by the
 149     specified PID. For processes which are not part of a login session
 150     and not managed by a user manager, this function will fail with
 151     <constant>-ENODATA</constant>.</para>
 152
 153     <para><function>sd_pid_get_session()</function> may be used to
 154     determine the login session identifier of a process identified by
 155     the specified process identifier. The session identifier is a
 156     short string, suitable for usage in file system paths. Please
 157     note the login session may be limited to a stub process or two.
 158     User processes may instead be started from their systemd user
 159     manager, e.g. GUI applications started using DBus activation, as
 160     well as service processes which are shared between multiple logins
 161     of the same user. For processes which are not part of a login
 162     session, this function will fail with <constant>-ENODATA</constant>.
 163     The returned string needs to be freed with the libc <citerefentry
 164     project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 165     call after use.</para>
 166
 167     <para><function>sd_pid_get_user_unit()</function> may be used to
 168     determine the systemd user unit (i.e. user service or scope unit)
 169     identifier of a process identified by the specified PID. The
 170     unit name is a short string, suitable for usage in file system
 171     paths. For processes which are not managed by a user manager, this
 172     function will fail with <constant>-ENODATA</constant>. The
 173     returned string needs to be freed with the libc <citerefentry
 174     project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 175     call after use.</para>
 176
 177     <para><function>sd_pid_get_unit()</function> may be used to
 178     determine the systemd system unit (i.e. system service or scope
 179     unit) identifier of a process identified by the specified PID. The
 180     unit name is a short string, suitable for usage in file system
 181     paths.  Note that not all processes are part of a system
 182     unit/service. For processes not being part of a systemd system
 183     unit, this function will fail with <constant>-ENODATA</constant>.
 184     (More specifically, this call will not work for kernel threads.)
 185     The returned string needs to be freed with the libc <citerefentry
 186     project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 187     call after use.</para>
 188
 189     <para><function>sd_pid_get_machine_name()</function> may be used
 190     to determine the name of the VM or container is a member of. The
 191     machine name is a short string, suitable for usage in file system
 192     paths. The returned string needs to be freed with the libc
 193     <citerefentry
 194     project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 195     call after use. For processes not part of a VM or container, this
 196     function fails with <constant>-ENODATA</constant>.</para>
 197
 198     <para><function>sd_pid_get_slice()</function> may be used to
 199     determine the slice unit the process is a member of. See
 200     <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 201     for details about slices. The returned string needs to be freed
 202     with the libc
 203     <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 204     call after use.</para>
 205
 206     <para>Similarly, <function>sd_pid_get_user_slice()</function>
 207     returns the user slice (as managed by the user's systemd instance)
 208     of a process.</para>
 209
 210     <para><function>sd_pid_get_cgroup()</function> returns the control
 211     group path of the specified process, relative to the root of the
 212     hierarchy. Returns the path without trailing slash, except for
 213     processes located in the root control group, where "/" is
 214     returned. To find the actual control group path in the file system,
 215     the returned path needs to be prefixed with
 216     <filename>/sys/fs/cgroup/</filename> (if the unified control group
 217     setup is used), or
 218     <filename>/sys/fs/cgroup/<replaceable>HIERARCHY</replaceable>/</filename>
 219     (if the legacy multi-hierarchy control group setup is used).</para>
 220
 221     <para>If the <varname>pid</varname> parameter of any of these
 222     functions is passed as 0, the operation is executed for the
 223     calling process.</para>
 224
 225     <para>The <function>sd_peer_get_owner_uid()</function>,
 226     <function>sd_peer_get_session()</function>,
 227     <function>sd_peer_get_user_unit()</function>,
 228     <function>sd_peer_get_unit()</function>,
 229     <function>sd_peer_get_machine_name()</function>,
 230     <function>sd_peer_get_slice()</function>,
 231     <function>sd_peer_get_user_slice()</function> and
 232     <function>sd_peer_get_cgroup()</function> calls operate similarly to their PID counterparts, but accept a
 233     connected <constant>AF_UNIX</constant> socket and retrieve information about the connected peer process.
 234     Note that these fields are retrieved via <filename>/proc/</filename>, and hence are not suitable for
 235     authorization purposes, as they are subject to races.</para>
 236   </refsect1>
 237
 238   <refsect1>
 239     <title>Return Value</title>
 240
 241     <para>On success, these calls return 0 or a positive integer. On failure, these calls return a negative
 242     errno-style error code.</para>
 243
 244     <refsect2>
 245       <title>Errors</title>
 246
 247       <para>Returned errors may indicate the following problems:</para>
 248
 249       <variablelist>
 250
 251         <varlistentry>
 252           <term><constant>-ESRCH</constant></term>
 253
 254           <listitem><para>The specified PID does not refer to a running process.</para>
 255           </listitem>
 256         </varlistentry>
 257
 258         <varlistentry>
 259           <term><constant>-EBADF</constant></term>
 260
 261           <listitem><para>The specified socket file descriptor was invalid.</para></listitem>
 262         </varlistentry>
 263
 264         <varlistentry>
 265           <term><constant>-ENODATA</constant></term>
 266
 267           <listitem><para>The given field is not specified for the described process or peer.</para>
 268           </listitem>
 269         </varlistentry>
 270
 271         <varlistentry>
 272           <term><constant>-EINVAL</constant></term>
 273
 274           <listitem><para>An input parameter was invalid (out of range, or <constant>NULL</constant>, where
 275           that is not accepted).</para></listitem>
 276         </varlistentry>
 277
 278         <varlistentry>
 279           <term><constant>-ENOMEM</constant></term>
 280
 281           <listitem><para>Memory allocation failed.</para></listitem>
 282         </varlistentry>
 283       </variablelist>
 284     </refsect2>
 285   </refsect1>
 286
 287   <refsect1>
 288     <title>Notes</title>
 289
 290     <xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
 291
 292     <para>Note that the login session identifier as
 293     returned by <function>sd_pid_get_session()</function>
 294     is completely unrelated to the process session
 295     identifier as returned by
 296     <citerefentry><refentrytitle>getsid</refentrytitle><manvolnum>2</manvolnum></citerefentry>.</para>
 297   </refsect1>
 298
 299   <refsect1>
 300     <title>See Also</title>
 301
 302     <para>
 303       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 304       <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 305       <citerefentry><refentrytitle>sd_session_is_active</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 306       <citerefentry><refentrytitle>getsid</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
 307       <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 308       <citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 309     </para>
 310   </refsect1>
 311
 312 </refentry>