systemd/man/sd_bus_creds_get_pid.xml

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<refentry id="sd_bus_creds_get_pid" conditional="ENABLE_KDBUS">

  <refentryinfo>
    <title>sd_bus_creds_get_pid</title>
    <productname>systemd</productname>

    <authorgroup>
      <author>
        <contrib>A monkey with a typewriter</contrib>
        <firstname>Zbigniew</firstname>
        <surname>Jędrzejewski-Szmek</surname>
        <email>zbyszek@in.waw.pl</email>
      </author>
    </authorgroup>
  </refentryinfo>

  <refmeta>
    <refentrytitle>sd_bus_creds_get_pid</refentrytitle>
    <manvolnum>3</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>sd_bus_creds_get_pid</refname>
    <refname>sd_bus_creds_get_ppid</refname>
    <refname>sd_bus_creds_get_tid</refname>
    <refname>sd_bus_creds_get_uid</refname>
    <refname>sd_bus_creds_get_euid</refname>
    <refname>sd_bus_creds_get_suid</refname>
    <refname>sd_bus_creds_get_fsuid</refname>
    <refname>sd_bus_creds_get_gid</refname>
    <refname>sd_bus_creds_get_egid</refname>
    <refname>sd_bus_creds_get_sgid</refname>
    <refname>sd_bus_creds_get_fsgid</refname>
    <refname>sd_bus_creds_get_supplementary_gids</refname>
    <refname>sd_bus_creds_get_comm</refname>
    <refname>sd_bus_creds_get_tid_comm</refname>
    <refname>sd_bus_creds_get_exe</refname>
    <refname>sd_bus_creds_get_cmdline</refname>
    <refname>sd_bus_creds_get_cgroup</refname>
    <refname>sd_bus_creds_get_unit</refname>
    <refname>sd_bus_creds_get_user_unit</refname>
    <refname>sd_bus_creds_get_slice</refname>
    <refname>sd_bus_creds_get_session</refname>
    <refname>sd_bus_creds_get_owner_uid</refname>
    <refname>sd_bus_creds_has_effective_cap</refname>
    <refname>sd_bus_creds_has_permitted_cap</refname>
    <refname>sd_bus_creds_has_inheritable_cap</refname>
    <refname>sd_bus_creds_has_bounding_cap</refname>
    <refname>sd_bus_creds_get_selinux_context</refname>
    <refname>sd_bus_creds_get_audit_session_id</refname>
    <refname>sd_bus_creds_get_audit_login_uid</refname>
    <refname>sd_bus_creds_get_tty</refname>
    <refname>sd_bus_creds_get_unique_name</refname>
    <refname>sd_bus_creds_get_well_known_names</refname>
    <refname>sd_bus_creds_get_description</refname>

    <refpurpose>Retrieve fields from a credentials object</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_pid</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>pid_t *<parameter>pid</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_ppid</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>pid_t *<parameter>ppid</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_tid</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>pid_t *<parameter>tid</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_uid</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>uid_t *<parameter>uid</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_euid</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>uid_t *<parameter>uid</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_suid</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>uid_t *<parameter>uid</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_fsuid</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>uid_t *<parameter>uid</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_gid</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>gid_t *<parameter>gid</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_egid</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>gid_t *<parameter>gid</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_sgid</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>gid_t *<parameter>gid</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_fsgid</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>gid_t *<parameter>gid</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_supplementary_gids</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>const gid_t **<parameter>gids</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_comm</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>const char **<parameter>comm</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_tid_comm</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>const char **<parameter>comm</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_exe</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>const char **<parameter>exe</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_cmdline</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>char ***<parameter>cmdline</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_cgroup</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>const char **<parameter>cgroup</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_unit</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>const char **<parameter>unit</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_user_unit</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>const char **<parameter>unit</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_slice</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>const char **<parameter>slice</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_session</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>const char **<parameter>slice</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_owner_uid</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>uid_t *<parameter>uid</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_has_effective_cap</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>int <parameter>capability</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_has_permitted_cap</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>int <parameter>capability</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_has_inheritable_cap</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>int <parameter>capability</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_has_bounding_cap</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>int <parameter>capability</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_selinux_context</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>const char **<parameter>context</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_audit_session_id</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>uint32_t *<parameter>sessionid</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_audit_login_uid</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>uid_t *<parameter>loginuid</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_tty</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>const char **<parameter>tty</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_unique_name</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>const char **<parameter>name</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_well_known_names</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>char ***<parameter>name</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_get_description</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
        <paramdef>const char **<parameter>name</parameter></paramdef>
      </funcprototype>

    </funcsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>These functions return information from an
    <parameter>sd_bus_creds</parameter> credential object. Credential
    objects may be created with
    <citerefentry><refentrytitle>sd_bus_creds_new_from_pid</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
    in which case they describe the credentials of the process
    identified by the specified PID, with
    <citerefentry><refentrytitle>sd_bus_get_name_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
    in which case they describe the credentials of a bus peer
    identified by the specified bus name, or with
    <citerefentry><refentrytitle>sd_bus_get_owner_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
    in which case they describe the credentials of the creator of a
    bus.</para>

    <para><function>sd_bus_creds_get_pid()</function> will retrieve
    the PID (process identifier). Similar,
    <function>sd_bus_creds_get_ppid()</function> will retrieve the
    parent PID. Note that PID 1 has no parent process, in which case
    -ENXIO is returned.</para>

    <para><function>sd_bus_creds_get_tid()</function> will retrieve the
    TID (thread identifier).</para>

    <para><function>sd_bus_creds_get_uid()</function> will retrieve
    the numeric UID (user identifier). Similar,
    <function>sd_bus_creds_get_euid()</function> returns the effective
    UID, <function>sd_bus_creds_get_suid()</function> the saved UID
    and <function>sd_bus_creds_get_fsuid()</function> the file system
    UID.</para>

    <para><function>sd_bus_creds_get_gid()</function> will retrieve the
    numeric GID (group identifier). Similar,
    <function>sd_bus_creds_get_egid()</function> returns the effective
    GID, <function>sd_bus_creds_get_sgid()</function> the saved GID
    and <function>sd_bus_creds_get_fsgid()</function> the file system
    GID.</para>

    <para><function>sd_bus_creds_get_supplementary_gids()</function>
    will retrieve the supplementary GIDs list.</para>

    <para><function>sd_bus_creds_get_comm()</function> will retrieve the
    comm field (truncated name of the executable, as stored in
    <filename>/proc/<replaceable>pid</replaceable>/comm</filename>).
    </para>

    <para><function>sd_bus_creds_get_tid_comm()</function> will retrieve
    the comm field of the thread (as stored in
    <filename>/proc/<replaceable>pid</replaceable>/task/<replaceable>tid</replaceable>/comm</filename>).
    </para>

    <para><function>sd_bus_creds_get_exe()</function> will retrieve
    the path to the program executable (as stored in the
    <filename>/proc/<replaceable>pid</replaceable>/exe</filename>
    link, but with <literal> (deleted)</literal> suffix removed). Note
    that kernel threads do not have an executable path, in which case
    -ENXIO is returned.</para>

    <para><function>sd_bus_creds_get_cmdline()</function> will
    retrieve an array of command line arguments (as stored in
    <filename>/proc/<replaceable>pid</replaceable>/cmdline</filename>). Note
    that kernel threads do not have a command line, in which case
    -ENXIO is returned.</para>

    <para><function>sd_bus_creds_get_cgroup()</function> will retrieve
    the cgroup path. See <ulink
    url="https://www.kernel.org/doc/Documentation/cgroups/cgroups.txt">cgroups.txt</ulink>.
    </para>

    <para><function>sd_bus_creds_get_unit()</function> will retrieve
    the systemd unit name (in the system instance of systemd) that the
    process is part of. See
    <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. For
    processes that are not part of a unit returns -ENXIO.
    </para>

    <para><function>sd_bus_creds_get_user_unit()</function> will
    retrieve the systemd unit name (in the user instance of systemd)
    that the process is part of. See
    <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. For
    processes that are not part of a user unit returns -ENXIO.
    </para>

    <para><function>sd_bus_creds_get_slice()</function> will retrieve
    the systemd slice (a unit in the system instance of systemd) that
    the process is part of. See
    <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
    </para>

    <para><function>sd_bus_creds_get_session()</function> will
    retrieve the logind session that the process is part of. See
    <citerefentry><refentrytitle>systemd-logind.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. For
    processes that are not part of a session returns -ENXIO.
    </para>

    <para><function>sd_bus_creds_get_owner_uid()</function> will
    retrieve the numeric UID (user identifier) of the user who owns
    the session that the process is part of. See
    <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
    For processes that are not part of a session returns -ENXIO.
    </para>

    <para><function>sd_bus_creds_has_effective_cap()</function> will
    check whether the capability specified by
    <parameter>capability</parameter> was set in the effective
    capabilities mask. A positive return value means that is was
    set, zero means that it was not set, and a negative return
    value signifies an error. See
    <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
    and <varname>Capabilities=</varname> and
    <varname>CapabilityBoundingSet=</varname> settings in
    <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
    </para>

    <para><function>sd_bus_creds_has_permitted_cap()</function> is
    similar to <function>sd_bus_creds_has_effective_cap()</function>,
    but will check the permitted capabilities mask.</para>

    <para><function>sd_bus_creds_has_inheritable_cap()</function> is
    similar to <function>sd_bus_creds_has_effective_cap()</function>,
    but will check the inheritable capabilities mask.</para>

    <para><function>sd_bus_creds_has_bounding_cap()</function> is
    similar to <function>sd_bus_creds_has_effective_cap()</function>,
    but will check the bounding capabilities mask.</para>

    <para><function>sd_bus_creds_get_selinux_context()</function> will
    retrieve the SELinux security context (label) of the process.</para>

    <para><function>sd_bus_creds_get_audit_session_id()</function>
    will retrieve the audit session identifier of the process. Returns
    -ENXIO for processes that are not part of an audit session.</para>

    <para><function>sd_bus_creds_get_audit_login_uid()</function> will
    retrieve the audit user login identifier (the identifier of the
    user who is "responsible" for the session). Returns -ENXIO for
    processes that are not part of an audit session.</para>

    <para><function>sd_bus_creds_get_tty()</function> will retrieve
    the controlling TTY. Returns -ENXIO for processes that have no
    controlling TTY.</para>

    <para><function>sd_bus_creds_get_unique_name()</function> will
    retrieve the D-Bus unique name. See <ulink
    url="http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names-bus">The
    D-Bus specification</ulink>.</para>

    <para><function>sd_bus_creds_get_well_known_names()</function> will
    retrieve the set of D-Bus well-known names. See <ulink
    url="http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names-bus">The
    D-Bus specification</ulink>.</para>

    <para><function>sd_bus_creds_get_description()</function> will
    retrieve a descriptive name of the bus connection of the
    peer. This name is useful to discern multiple bus connections by
    the same peer, and may be altered by the peer with the
    <citerefentry><refentrytitle>sd_bus_set_description</refentrytitle><manvolnum>3</manvolnum></citerefentry>
    call.</para>

    <para>All functions that take a <parameter>const
    char**</parameter> parameter will store the answer there as an
    address of a NUL-terminated string. It will be valid as long as
    <parameter>c</parameter> remains valid, and should not be freed or
    modified by the caller.</para>

    <para>All functions that take a <parameter>char***</parameter>
    parameter will store the answer there as an address of a an array
    of strings. Each invidividual string is NUL-terminated, and the
    array is NULL-terminated as a whole. It will be valid as long as
    <parameter>c</parameter> remains valid, and should not be freed or
    modified by the caller.</para>
  </refsect1>

  <refsect1>
    <title>Return Value</title>

    <para>On success, these calls return 0 or a positive integer. On
    failure, these calls return a negative errno-style error code.
    </para>
  </refsect1>

  <refsect1>
    <title>Errors</title>

    <para>Returned errors may indicate the following problems:</para>

    <variablelist>
      <varlistentry>
        <term><constant>-ENODATA</constant></term>

        <listitem><para>Given field is not available in the
        credentials object <parameter>c</parameter>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>-ENXIO</constant></term>

        <listitem><para>Given field is not specified for the described
        process or peer. This will be returned by
        <function>sd_bus_get_unit()</function>,
        <function>sd_bus_get_user_unit()</function>,
        <function>sd_bus_get_slice()</function>,
        <function>sd_bus_get_session()</function>, and
        <function>sd_bus_get_owner_uid()</function> if the process is
        not part of a systemd system unit, systemd user unit, systemd
        slice, or logind session. It will also be returned by
        <function>sd_bus_creds_get_exe()</function> and
        <function>sd_bus_creds_get_cmdline()</function> for kernel
        threads (since these aren't started from an executable binary
        or have a command line),
        <function>sd_bus_creds_get_audit_session_id()</function> and
        <function>sd_bus_creds_get_audit_login_uid()</function> when
        the process is not part of an audit session, and
        <function>sd_bus_creds_get_tty()</function> if the process has
        no controlling TTY.
        </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>-EINVAL</constant></term>

        <listitem><para>Specified pointer parameter is <constant>NULL</constant>.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>-ENOMEM</constant></term>

        <listitem><para>Memory allocation failed.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Notes</title>

    <para><function>sd_bus_open_user()</function> and other functions
    described here are available as a shared library, which can be
    compiled and linked to with the
    <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    file.</para>
  </refsect1>

  <refsect1>
    <title>See Also</title>

    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>fork</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>credentials</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>proc</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>