systemd/man/sd_bus_creds_new_from_pid.xml

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<refentry id="sd_bus_creds_new_from_pid" xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>sd_bus_creds_new_from_pid</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>sd_bus_creds_new_from_pid</refentrytitle>
    <manvolnum>3</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>sd_bus_creds_new_from_pid</refname>
    <refname>sd_bus_creds_new_from_pidfd</refname>
    <refname>sd_bus_creds_get_mask</refname>
    <refname>sd_bus_creds_get_augmented_mask</refname>
    <refname>sd_bus_creds_ref</refname>
    <refname>sd_bus_creds_unref</refname>
    <refname>sd_bus_creds_unrefp</refname>

    <refpurpose>Retrieve credentials object for the specified PID</refpurpose>
  </refnamediv>

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

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_new_from_pid</function></funcdef>
        <paramdef>pid_t <parameter>pid</parameter></paramdef>
        <paramdef>uint64_t <parameter>creds_mask</parameter></paramdef>
        <paramdef>sd_bus_creds **<parameter>ret</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>int <function>sd_bus_creds_new_from_pidfd</function></funcdef>
        <paramdef>int <parameter>pidfd</parameter></paramdef>
        <paramdef>uint64_t <parameter>creds_mask</parameter></paramdef>
        <paramdef>sd_bus_creds **<parameter>ret</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>uint64_t <function>sd_bus_creds_get_mask</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>uint64_t <function>sd_bus_creds_get_augmented_mask</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>sd_bus_creds *<function>sd_bus_creds_ref</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>sd_bus_creds *<function>sd_bus_creds_unref</function></funcdef>
        <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
      </funcprototype>

      <funcprototype>
        <funcdef>void <function>sd_bus_creds_unrefp</function></funcdef>
        <paramdef>sd_bus_creds **<parameter>c</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>

    <para>
      <constant>SD_BUS_CREDS_PID</constant>,
      <constant>SD_BUS_CREDS_PPID</constant>,
      <constant>SD_BUS_CREDS_TID</constant>,
      <constant>SD_BUS_CREDS_UID</constant>,
      <constant>SD_BUS_CREDS_EUID</constant>,
      <constant>SD_BUS_CREDS_SUID</constant>,
      <constant>SD_BUS_CREDS_FSUID</constant>,
      <constant>SD_BUS_CREDS_GID</constant>,
      <constant>SD_BUS_CREDS_EGID</constant>,
      <constant>SD_BUS_CREDS_SGID</constant>,
      <constant>SD_BUS_CREDS_FSGID</constant>,
      <constant>SD_BUS_CREDS_SUPPLEMENTARY_GIDS</constant>,
      <constant>SD_BUS_CREDS_COMM</constant>,
      <constant>SD_BUS_CREDS_TID_COMM</constant>,
      <constant>SD_BUS_CREDS_EXE</constant>,
      <constant>SD_BUS_CREDS_CMDLINE</constant>,
      <constant>SD_BUS_CREDS_CGROUP</constant>,
      <constant>SD_BUS_CREDS_UNIT</constant>,
      <constant>SD_BUS_CREDS_SLICE</constant>,
      <constant>SD_BUS_CREDS_USER_UNIT</constant>,
      <constant>SD_BUS_CREDS_USER_SLICE</constant>,
      <constant>SD_BUS_CREDS_SESSION</constant>,
      <constant>SD_BUS_CREDS_OWNER_UID</constant>,
      <constant>SD_BUS_CREDS_EFFECTIVE_CAPS</constant>,
      <constant>SD_BUS_CREDS_PERMITTED_CAPS</constant>,
      <constant>SD_BUS_CREDS_INHERITABLE_CAPS</constant>,
      <constant>SD_BUS_CREDS_BOUNDING_CAPS</constant>,
      <constant>SD_BUS_CREDS_SELINUX_CONTEXT</constant>,
      <constant>SD_BUS_CREDS_AUDIT_SESSION_ID</constant>,
      <constant>SD_BUS_CREDS_AUDIT_LOGIN_UID</constant>,
      <constant>SD_BUS_CREDS_TTY</constant>,
      <constant>SD_BUS_CREDS_UNIQUE_NAME</constant>,
      <constant>SD_BUS_CREDS_WELL_KNOWN_NAMES</constant>,
      <constant>SD_BUS_CREDS_DESCRIPTION</constant>,
      <constant>SD_BUS_CREDS_PIDFD</constant>,
      <constant>SD_BUS_CREDS_AUGMENT</constant>,
      <constant>_SD_BUS_CREDS_ALL</constant>
    </para>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><function>sd_bus_creds_new_from_pid()</function> creates a
    new credentials object and fills it with information about the
    process <parameter>pid</parameter>. The pointer to this object
    will be stored in the <parameter>ret</parameter> pointer. Note that
    credential objects may also be created and retrieved via
    <citerefentry><refentrytitle>sd_bus_get_name_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
    <citerefentry><refentrytitle>sd_bus_get_owner_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
    and
    <citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>

    <para><function>sd_bus_creds_new_from_pidfd()</function> is identical to
    <function>sd_bus_creds_new_from_pid()</function>, but takes a PID file descriptor rather than a numeric
    PID as reference to the process. See <citerefentry
    project='man-pages'><refentrytitle>pidfd_open</refentrytitle><manvolnum>2</manvolnum></citerefentry>.</para>

    <para>The information that will be stored is determined by <parameter>creds_mask</parameter>. It may
    contain a subset of ORed constants <constant>SD_BUS_CREDS_PID</constant>,
    <constant>SD_BUS_CREDS_PPID</constant>, <constant>SD_BUS_CREDS_TID</constant>,
    <constant>SD_BUS_CREDS_UID</constant>, <constant>SD_BUS_CREDS_EUID</constant>,
    <constant>SD_BUS_CREDS_SUID</constant>, <constant>SD_BUS_CREDS_FSUID</constant>,
    <constant>SD_BUS_CREDS_GID</constant>, <constant>SD_BUS_CREDS_EGID</constant>,
    <constant>SD_BUS_CREDS_SGID</constant>, <constant>SD_BUS_CREDS_FSGID</constant>,
    <constant>SD_BUS_CREDS_SUPPLEMENTARY_GIDS</constant>, <constant>SD_BUS_CREDS_COMM</constant>,
    <constant>SD_BUS_CREDS_TID_COMM</constant>, <constant>SD_BUS_CREDS_EXE</constant>,
    <constant>SD_BUS_CREDS_CMDLINE</constant>, <constant>SD_BUS_CREDS_CGROUP</constant>,
    <constant>SD_BUS_CREDS_UNIT</constant>, <constant>SD_BUS_CREDS_SLICE</constant>,
    <constant>SD_BUS_CREDS_USER_UNIT</constant>, <constant>SD_BUS_CREDS_USER_SLICE</constant>,
    <constant>SD_BUS_CREDS_SESSION</constant>, <constant>SD_BUS_CREDS_OWNER_UID</constant>,
    <constant>SD_BUS_CREDS_EFFECTIVE_CAPS</constant>, <constant>SD_BUS_CREDS_PERMITTED_CAPS</constant>,
    <constant>SD_BUS_CREDS_INHERITABLE_CAPS</constant>, <constant>SD_BUS_CREDS_BOUNDING_CAPS</constant>,
    <constant>SD_BUS_CREDS_SELINUX_CONTEXT</constant>, <constant>SD_BUS_CREDS_AUDIT_SESSION_ID</constant>,
    <constant>SD_BUS_CREDS_AUDIT_LOGIN_UID</constant>, <constant>SD_BUS_CREDS_TTY</constant>,
    <constant>SD_BUS_CREDS_UNIQUE_NAME</constant>, <constant>SD_BUS_CREDS_WELL_KNOWN_NAMES</constant>,
    <constant>SD_BUS_CREDS_DESCRIPTION</constant>, and <constant>SD_BUS_CREDS_PIDFD</constant>. Use the
    special value <constant>_SD_BUS_CREDS_ALL</constant> to request all supported fields. The
    <constant>SD_BUS_CREDS_AUGMENT</constant> constant may not be ORed into the mask for invocations of
    <function>sd_bus_creds_new_from_pid()</function> or
    <function>sd_bus_creds_new_from_pidfd()</function>.</para>

    <para>Fields can be retrieved from the credentials object using
    <citerefentry><refentrytitle>sd_bus_creds_get_pid</refentrytitle><manvolnum>3</manvolnum></citerefentry>
    and other functions which correspond directly to the constants
    listed above.</para>

    <para>A mask of fields which were actually successfully retrieved can be retrieved with
    <function>sd_bus_creds_get_mask()</function>. If the credentials object was created with
    <function>sd_bus_creds_new_from_pid()</function> or <function>sd_bus_creds_new_from_pidfd()</function>,
    this will be a subset of fields requested in <parameter>creds_mask</parameter>.
    </para>

    <para>Similar to <function>sd_bus_creds_get_mask()</function>, the function
    <function>sd_bus_creds_get_augmented_mask()</function> returns a bitmask of field constants. The mask
    indicates which credential fields have been retrieved in a non-atomic fashion. For credential objects
    created via <function>sd_bus_creds_new_from_pid()</function> or
    <function>sd_bus_creds_new_from_pidfd()</function>, this mask will be identical to the mask returned by
    <function>sd_bus_creds_get_mask()</function>. However, for credential objects retrieved via
    <function>sd_bus_get_name_creds()</function>, this mask will be set for the credential fields that could
    not be determined atomically at peer connection time, and which were later added by reading augmenting
    credential data from <filename>/proc/</filename>. Similarly, for credential objects retrieved via
    <function>sd_bus_get_owner_creds()</function>, the mask is set for the fields that could not be
    determined atomically at bus creation time, but have been augmented. Similarly, for credential objects
    retrieved via <function>sd_bus_message_get_creds()</function>, the mask is set for the fields that could
    not be determined atomically at message sending time, but have been augmented. The mask returned by
    <function>sd_bus_creds_get_augmented_mask()</function> is always a subset of (or identical to) the mask
    returned by <function>sd_bus_creds_get_mask()</function> for the same object. The latter call hence
    returns all credential fields available in the credential object, the former then marks the subset of
    those that have been augmented. Note that augmented fields are unsuitable for authorization decisions, as
    they may be retrieved at different times, thus being subject to races. Hence, augmented fields should be
    used exclusively for informational purposes.
    </para>

    <para><function>sd_bus_creds_ref()</function> creates a new
    reference to the credentials object <parameter>c</parameter>. This
    object will not be destroyed until
    <function>sd_bus_creds_unref()</function> has been called as many
    times plus once more. Once the reference count has dropped to zero,
    <parameter>c</parameter> cannot be used anymore, so further
    calls to <function>sd_bus_creds_ref(c)</function> or
    <function>sd_bus_creds_unref(c)</function> are illegal.</para>

    <para><function>sd_bus_creds_unref()</function> destroys a reference
    to <parameter>c</parameter>.</para>

    <para><function>sd_bus_creds_unrefp()</function> is similar to
    <function>sd_bus_creds_unref()</function> but takes a pointer to a
    pointer to an <type>sd_bus_creds</type> object. This call is useful in
    conjunction with GCC's and LLVM's <ulink
    url="https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html">Clean-up
    Variable Attribute</ulink>. Note that this function is defined as
    inline function.</para>

    <para><function>sd_bus_creds_ref()</function>,
    <function>sd_bus_creds_unref()</function> and
    <function>sd_bus_creds_unrefp()</function> execute no operation if
    the passed in bus credentials object is
    <constant>NULL</constant>.</para>

  </refsect1>

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

    <para>On success, <function>sd_bus_creds_new_from_pid()</function> and
    <function>sd_bus_creds_new_from_pidfd()</function> return 0 or a positive integer. On failure, they return
    a negative errno-style error code.</para>

    <para><function>sd_bus_creds_get_mask()</function> returns the
    mask of successfully acquired fields.</para>

    <para><function>sd_bus_creds_get_augmented_mask()</function>
    returns the mask of fields that have been augmented from data in
    <filename>/proc/</filename>, and are thus not suitable for
    authorization decisions.</para>

    <para><function>sd_bus_creds_ref()</function> always returns the
    argument.</para>

    <para><function>sd_bus_creds_unref()</function> always returns
    <constant>NULL</constant>.</para>
  </refsect1>

  <refsect1>
    <title>Reference ownership</title>

    <para>The functions <function>sd_bus_creds_new_from_pid()</function> and
    <function>sd_bus_creds_new_from_pidfd()</function> create a new object and the caller owns the sole
    reference. When not needed anymore, this reference should be destroyed with
    <citerefentry><refentrytitle>sd_bus_creds_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
    </para>

    <refsect2>
      <title>Errors</title>

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

      <variablelist>

        <varlistentry>
          <term><constant>-ESRCH</constant></term>

          <listitem><para>Specified <parameter>pid</parameter> could not be found.</para></listitem>
        </varlistentry>

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

          <listitem><para>Specified parameter is invalid (<constant>NULL</constant> in case of output
          parameters).</para></listitem>
        </varlistentry>

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

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

        <varlistentry>
          <term><constant>-EOPNOTSUPP</constant></term>

          <listitem><para>One of the requested fields is unknown to the local system.</para></listitem>
        </varlistentry>
      </variablelist>
    </refsect2>
  </refsect1>

  <xi:include href="libsystemd-pkgconfig.xml" />

  <refsect1>
    <title>History</title>
    <para><function>sd_bus_creds_new_from_pid()</function>,
    <function>sd_bus_creds_get_mask()</function>,
    <function>sd_bus_creds_ref()</function>,
    <function>sd_bus_creds_unref()</function>, and
    <function>sd_bus_creds_get_augmented_mask()</function> were added in version 221.</para>
    <para><function>sd_bus_creds_unrefp()</function> was added in version 229.</para>
    <para><function>sd_bus_creds_new_from_pidfd()</function> was added in version 256.</para>
  </refsect1>

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

    <para><simplelist type="inline">
      <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>sd_bus_creds_get_pid</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>sd_bus_get_name_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>sd_bus_get_owner_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
    </simplelist></para>
  </refsect1>

</refentry>