man/sd_bus_creds_new_from_pid.xml

   1 <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7 -->
   8
   9 <refentry id="sd_bus_creds_new_from_pid" xmlns:xi="http://www.w3.org/2001/XInclude">
  10
  11   <refentryinfo>
  12     <title>sd_bus_creds_new_from_pid</title>
  13     <productname>systemd</productname>
  14
  15     <authorgroup>
  16       <author>
  17         <contrib>A monkey with a typewriter</contrib>
  18         <firstname>Zbigniew</firstname>
  19         <surname>Jędrzejewski-Szmek</surname>
  20         <email>zbyszek@in.waw.pl</email>
  21       </author>
  22     </authorgroup>
  23   </refentryinfo>
  24
  25   <refmeta>
  26     <refentrytitle>sd_bus_creds_new_from_pid</refentrytitle>
  27     <manvolnum>3</manvolnum>
  28   </refmeta>
  29
  30   <refnamediv>
  31     <refname>sd_bus_creds_new_from_pid</refname>
  32     <refname>sd_bus_creds_get_mask</refname>
  33     <refname>sd_bus_creds_get_augmented_mask</refname>
  34     <refname>sd_bus_creds_ref</refname>
  35     <refname>sd_bus_creds_unref</refname>
  36     <refname>sd_bus_creds_unrefp</refname>
  37
  38     <refpurpose>Retrieve credentials object for the specified PID</refpurpose>
  39   </refnamediv>
  40
  41   <refsynopsisdiv>
  42     <funcsynopsis>
  43       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  44
  45       <funcprototype>
  46         <funcdef>int <function>sd_bus_creds_new_from_pid</function></funcdef>
  47         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  48         <paramdef>uint64_t <parameter>creds_mask</parameter></paramdef>
  49         <paramdef>sd_bus_creds **<parameter>ret</parameter></paramdef>
  50       </funcprototype>
  51
  52       <funcprototype>
  53         <funcdef>uint64_t <function>sd_bus_creds_get_mask</function></funcdef>
  54         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  55       </funcprototype>
  56
  57       <funcprototype>
  58         <funcdef>uint64_t <function>sd_bus_creds_get_augmented_mask</function></funcdef>
  59         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  60       </funcprototype>
  61
  62       <funcprototype>
  63         <funcdef>sd_bus_creds *<function>sd_bus_creds_ref</function></funcdef>
  64         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  65       </funcprototype>
  66
  67       <funcprototype>
  68         <funcdef>sd_bus_creds *<function>sd_bus_creds_unref</function></funcdef>
  69         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  70       </funcprototype>
  71
  72       <funcprototype>
  73         <funcdef>void <function>sd_bus_creds_unrefp</function></funcdef>
  74         <paramdef>sd_bus_creds **<parameter>c</parameter></paramdef>
  75       </funcprototype>
  76     </funcsynopsis>
  77
  78     <para>
  79       <constant>SD_BUS_CREDS_PID</constant>,
  80       <constant>SD_BUS_CREDS_PPID</constant>,
  81       <constant>SD_BUS_CREDS_TID</constant>,
  82       <constant>SD_BUS_CREDS_UID</constant>,
  83       <constant>SD_BUS_CREDS_EUID</constant>,
  84       <constant>SD_BUS_CREDS_SUID</constant>,
  85       <constant>SD_BUS_CREDS_FSUID</constant>,
  86       <constant>SD_BUS_CREDS_GID</constant>,
  87       <constant>SD_BUS_CREDS_EGID</constant>,
  88       <constant>SD_BUS_CREDS_SGID</constant>,
  89       <constant>SD_BUS_CREDS_FSGID</constant>,
  90       <constant>SD_BUS_CREDS_SUPPLEMENTARY_GIDS</constant>,
  91       <constant>SD_BUS_CREDS_COMM</constant>,
  92       <constant>SD_BUS_CREDS_TID_COMM</constant>,
  93       <constant>SD_BUS_CREDS_EXE</constant>,
  94       <constant>SD_BUS_CREDS_CMDLINE</constant>,
  95       <constant>SD_BUS_CREDS_CGROUP</constant>,
  96       <constant>SD_BUS_CREDS_UNIT</constant>,
  97       <constant>SD_BUS_CREDS_SLICE</constant>,
  98       <constant>SD_BUS_CREDS_USER_UNIT</constant>,
  99       <constant>SD_BUS_CREDS_USER_SLICE</constant>,
 100       <constant>SD_BUS_CREDS_SESSION</constant>,
 101       <constant>SD_BUS_CREDS_OWNER_UID</constant>,
 102       <constant>SD_BUS_CREDS_EFFECTIVE_CAPS</constant>,
 103       <constant>SD_BUS_CREDS_PERMITTED_CAPS</constant>,
 104       <constant>SD_BUS_CREDS_INHERITABLE_CAPS</constant>,
 105       <constant>SD_BUS_CREDS_BOUNDING_CAPS</constant>,
 106       <constant>SD_BUS_CREDS_SELINUX_CONTEXT</constant>,
 107       <constant>SD_BUS_CREDS_AUDIT_SESSION_ID</constant>,
 108       <constant>SD_BUS_CREDS_AUDIT_LOGIN_UID</constant>,
 109       <constant>SD_BUS_CREDS_TTY</constant>,
 110       <constant>SD_BUS_CREDS_UNIQUE_NAME</constant>,
 111       <constant>SD_BUS_CREDS_WELL_KNOWN_NAMES</constant>,
 112       <constant>SD_BUS_CREDS_DESCRIPTION</constant>,
 113       <constant>SD_BUS_CREDS_AUGMENT</constant>,
 114       <constant>_SD_BUS_CREDS_ALL</constant>
 115     </para>
 116   </refsynopsisdiv>
 117
 118   <refsect1>
 119     <title>Description</title>
 120
 121     <para><function>sd_bus_creds_new_from_pid()</function> creates a
 122     new credentials object and fills it with information about the
 123     process <parameter>pid</parameter>. The pointer to this object
 124     will be stored in the <parameter>ret</parameter> pointer. Note that
 125     credential objects may also be created and retrieved via
 126     <citerefentry><refentrytitle>sd_bus_get_name_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 127     <citerefentry><refentrytitle>sd_bus_get_owner_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 128     and
 129     <citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
 130
 131     <para>The information that will be stored is determined by
 132     <parameter>creds_mask</parameter>. It may contain a subset of ORed
 133     constants <constant>SD_BUS_CREDS_PID</constant>,
 134     <constant>SD_BUS_CREDS_PPID</constant>,
 135     <constant>SD_BUS_CREDS_TID</constant>,
 136     <constant>SD_BUS_CREDS_UID</constant>,
 137     <constant>SD_BUS_CREDS_EUID</constant>,
 138     <constant>SD_BUS_CREDS_SUID</constant>,
 139     <constant>SD_BUS_CREDS_FSUID</constant>,
 140     <constant>SD_BUS_CREDS_GID</constant>,
 141     <constant>SD_BUS_CREDS_EGID</constant>,
 142     <constant>SD_BUS_CREDS_SGID</constant>,
 143     <constant>SD_BUS_CREDS_FSGID</constant>,
 144     <constant>SD_BUS_CREDS_SUPPLEMENTARY_GIDS</constant>,
 145     <constant>SD_BUS_CREDS_COMM</constant>,
 146     <constant>SD_BUS_CREDS_TID_COMM</constant>,
 147     <constant>SD_BUS_CREDS_EXE</constant>,
 148     <constant>SD_BUS_CREDS_CMDLINE</constant>,
 149     <constant>SD_BUS_CREDS_CGROUP</constant>,
 150     <constant>SD_BUS_CREDS_UNIT</constant>,
 151     <constant>SD_BUS_CREDS_SLICE</constant>,
 152     <constant>SD_BUS_CREDS_USER_UNIT</constant>,
 153     <constant>SD_BUS_CREDS_USER_SLICE</constant>,
 154     <constant>SD_BUS_CREDS_SESSION</constant>,
 155     <constant>SD_BUS_CREDS_OWNER_UID</constant>,
 156     <constant>SD_BUS_CREDS_EFFECTIVE_CAPS</constant>,
 157     <constant>SD_BUS_CREDS_PERMITTED_CAPS</constant>,
 158     <constant>SD_BUS_CREDS_INHERITABLE_CAPS</constant>,
 159     <constant>SD_BUS_CREDS_BOUNDING_CAPS</constant>,
 160     <constant>SD_BUS_CREDS_SELINUX_CONTEXT</constant>,
 161     <constant>SD_BUS_CREDS_AUDIT_SESSION_ID</constant>,
 162     <constant>SD_BUS_CREDS_AUDIT_LOGIN_UID</constant>,
 163     <constant>SD_BUS_CREDS_TTY</constant>,
 164     <constant>SD_BUS_CREDS_UNIQUE_NAME</constant>,
 165     <constant>SD_BUS_CREDS_WELL_KNOWN_NAMES</constant>, and
 166     <constant>SD_BUS_CREDS_DESCRIPTION</constant>. Use the special
 167     value <constant>_SD_BUS_CREDS_ALL</constant> to request all
 168     supported fields. The <constant>SD_BUS_CREDS_AUGMENT</constant>
 169     constant may not be ORed into the mask for invocations of
 170     <function>sd_bus_creds_new_from_pid()</function>.</para>
 171
 172     <para>Fields can be retrieved from the credentials object using
 173     <citerefentry><refentrytitle>sd_bus_creds_get_pid</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 174     and other functions which correspond directly to the constants
 175     listed above.</para>
 176
 177     <para>A mask of fields which were actually successfully retrieved
 178     can be retrieved with
 179     <function>sd_bus_creds_get_mask()</function>. If the credentials
 180     object was created with
 181     <function>sd_bus_creds_new_from_pid()</function>, this will be a
 182     subset of fields requested in <parameter>creds_mask</parameter>.
 183     </para>
 184
 185     <para>Similar to <function>sd_bus_creds_get_mask()</function>, the
 186     function <function>sd_bus_creds_get_augmented_mask()</function>
 187     returns a bitmask of field constants. The mask indicates which
 188     credential fields have been retrieved in a non-atomic fashion. For
 189     credential objects created via
 190     <function>sd_bus_creds_new_from_pid()</function>, this mask will be
 191     identical to the mask returned by
 192     <function>sd_bus_creds_get_mask()</function>. However, for
 193     credential objects retrieved via
 194     <function>sd_bus_get_name_creds()</function>, this mask will be set
 195     for the credential fields that could not be determined atomically
 196     at peer connection time, and which were later added by reading
 197     augmenting credential data from
 198     <filename>/proc</filename>. Similarly, for credential objects
 199     retrieved via <function>sd_bus_get_owner_creds()</function>, the
 200     mask is set for the fields that could not be determined atomically
 201     at bus creation time, but have been augmented. Similarly, for
 202     credential objects retrieved via
 203     <function>sd_bus_message_get_creds()</function>, the mask is set
 204     for the fields that could not be determined atomically at message
 205     sending time, but have been augmented. The mask returned by
 206     <function>sd_bus_creds_get_augmented_mask()</function> is always a
 207     subset of (or identical to) the mask returned by
 208     <function>sd_bus_creds_get_mask()</function> for the same
 209     object. The latter call hence returns all credential fields
 210     available in the credential object, the former then marks the
 211     subset of those that have been augmented. Note that augmented
 212     fields are unsuitable for authorization decisions, as they may be
 213     retrieved at different times, thus being subject to races. Hence,
 214     augmented fields should be used exclusively for informational
 215     purposes.
 216     </para>
 217
 218     <para><function>sd_bus_creds_ref()</function> creates a new
 219     reference to the credentials object <parameter>c</parameter>. This
 220     object will not be destroyed until
 221     <function>sd_bus_creds_unref()</function> has been called as many
 222     times plus once more. Once the reference count has dropped to zero,
 223     <parameter>c</parameter> cannot be used anymore, so further
 224     calls to <function>sd_bus_creds_ref(c)</function> or
 225     <function>sd_bus_creds_unref(c)</function> are illegal.</para>
 226
 227     <para><function>sd_bus_creds_unref()</function> destroys a reference
 228     to <parameter>c</parameter>.</para>
 229
 230     <para><function>sd_bus_creds_unrefp()</function> is similar to
 231     <function>sd_bus_creds_unref()</function> but takes a pointer to a
 232     pointer to an <type>sd_bus_creds</type> object. This call is useful in
 233     conjunction with GCC's and LLVM's <ulink
 234     url="https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html">Clean-up
 235     Variable Attribute</ulink>. Note that this function is defined as
 236     inline function.</para>
 237
 238     <para><function>sd_bus_creds_ref()</function>,
 239     <function>sd_bus_creds_unref()</function> and
 240     <function>sd_bus_creds_unrefp()</function> execute no operation if
 241     the passed in bus credentials object is
 242     <constant>NULL</constant>.</para>
 243
 244   </refsect1>
 245
 246   <refsect1>
 247     <title>Return Value</title>
 248
 249     <para>On success, <function>sd_bus_creds_new_from_pid()</function>
 250     returns 0 or a positive integer. On failure, it returns a negative
 251     errno-style error code.</para>
 252
 253     <para><function>sd_bus_creds_get_mask()</function> returns the
 254     mask of successfully acquired fields.</para>
 255
 256     <para><function>sd_bus_creds_get_augmented_mask()</function>
 257     returns the mask of fields that have been augmented from data in
 258     <filename>/proc</filename>, and are thus not suitable for
 259     authorization decisions.</para>
 260
 261     <para><function>sd_bus_creds_ref()</function> always returns the
 262     argument.</para>
 263
 264     <para><function>sd_bus_creds_unref()</function> always returns
 265     <constant>NULL</constant>.</para>
 266   </refsect1>
 267
 268   <refsect1>
 269     <title>Reference ownership</title>
 270
 271     <para>Function <function>sd_bus_creds_new_from_pid()</function>
 272     creates a new object and the caller owns the sole reference. When
 273     not needed anymore, this reference should be destroyed with
 274     <citerefentry><refentrytitle>sd_bus_creds_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 275     </para>
 276   </refsect1>
 277
 278   <refsect1>
 279     <title>Errors</title>
 280
 281     <para>Returned errors may indicate the following problems:</para>
 282
 283     <variablelist>
 284
 285       <varlistentry>
 286         <term><constant>-ESRCH</constant></term>
 287
 288         <listitem><para>Specified <parameter>pid</parameter> could not
 289         be found.</para></listitem>
 290       </varlistentry>
 291
 292       <varlistentry>
 293         <term><constant>-EINVAL</constant></term>
 294
 295         <listitem><para>Specified parameter is invalid
 296         (<constant>NULL</constant> in case of output
 297         parameters).</para></listitem>
 298       </varlistentry>
 299
 300       <varlistentry>
 301         <term><constant>-ENOMEM</constant></term>
 302
 303         <listitem><para>Memory allocation failed.</para></listitem>
 304       </varlistentry>
 305
 306       <varlistentry>
 307         <term><constant>-EOPNOTSUPP</constant></term>
 308
 309         <listitem><para>One of the requested fields is unknown to the local system.</para></listitem>
 310       </varlistentry>
 311     </variablelist>
 312   </refsect1>
 313
 314   <xi:include href="libelogind-pkgconfig.xml" />
 315
 316   <refsect1>
 317     <title>See Also</title>
 318
 319     <para>
 320       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 321       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 322       <citerefentry><refentrytitle>sd_bus_creds_get_pid</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 323       <citerefentry><refentrytitle>sd_bus_get_name_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 324       <citerefentry><refentrytitle>sd_bus_get_owner_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 325       <citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 326     </para>
 327   </refsect1>
 328
 329 </refentry>