man/sd_bus_creds_new_from_pid.xml

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   8   This file is part of systemd.
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  10   Copyright 2014 Zbigniew Jędrzejewski-Szmek
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  12
  13 <refentry id="sd_bus_creds_new_from_pid" xmlns:xi="http://www.w3.org/2001/XInclude">
  14
  15   <refentryinfo>
  16     <title>sd_bus_creds_new_from_pid</title>
  17     <productname>systemd</productname>
  18
  19     <authorgroup>
  20       <author>
  21         <contrib>A monkey with a typewriter</contrib>
  22         <firstname>Zbigniew</firstname>
  23         <surname>Jędrzejewski-Szmek</surname>
  24         <email>zbyszek@in.waw.pl</email>
  25       </author>
  26     </authorgroup>
  27   </refentryinfo>
  28
  29   <refmeta>
  30     <refentrytitle>sd_bus_creds_new_from_pid</refentrytitle>
  31     <manvolnum>3</manvolnum>
  32   </refmeta>
  33
  34   <refnamediv>
  35     <refname>sd_bus_creds_new_from_pid</refname>
  36     <refname>sd_bus_creds_get_mask</refname>
  37     <refname>sd_bus_creds_get_augmented_mask</refname>
  38     <refname>sd_bus_creds_ref</refname>
  39     <refname>sd_bus_creds_unref</refname>
  40     <refname>sd_bus_creds_unrefp</refname>
  41
  42     <refpurpose>Retrieve credentials object for the specified PID</refpurpose>
  43   </refnamediv>
  44
  45   <refsynopsisdiv>
  46     <funcsynopsis>
  47       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  48
  49       <funcprototype>
  50         <funcdef>int <function>sd_bus_creds_new_from_pid</function></funcdef>
  51         <paramdef>pid_t <parameter>pid</parameter></paramdef>
  52         <paramdef>uint64_t <parameter>creds_mask</parameter></paramdef>
  53         <paramdef>sd_bus_creds **<parameter>ret</parameter></paramdef>
  54       </funcprototype>
  55
  56       <funcprototype>
  57         <funcdef>uint64_t <function>sd_bus_creds_get_mask</function></funcdef>
  58         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  59       </funcprototype>
  60
  61       <funcprototype>
  62         <funcdef>uint64_t <function>sd_bus_creds_get_augmented_mask</function></funcdef>
  63         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  64       </funcprototype>
  65
  66       <funcprototype>
  67         <funcdef>sd_bus_creds *<function>sd_bus_creds_ref</function></funcdef>
  68         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  69       </funcprototype>
  70
  71       <funcprototype>
  72         <funcdef>sd_bus_creds *<function>sd_bus_creds_unref</function></funcdef>
  73         <paramdef>sd_bus_creds *<parameter>c</parameter></paramdef>
  74       </funcprototype>
  75
  76       <funcprototype>
  77         <funcdef>void <function>sd_bus_creds_unrefp</function></funcdef>
  78         <paramdef>sd_bus_creds **<parameter>c</parameter></paramdef>
  79       </funcprototype>
  80     </funcsynopsis>
  81
  82     <para>
  83       <constant>SD_BUS_CREDS_PID</constant>,
  84       <constant>SD_BUS_CREDS_PPID</constant>,
  85       <constant>SD_BUS_CREDS_TID</constant>,
  86       <constant>SD_BUS_CREDS_UID</constant>,
  87       <constant>SD_BUS_CREDS_EUID</constant>,
  88       <constant>SD_BUS_CREDS_SUID</constant>,
  89       <constant>SD_BUS_CREDS_FSUID</constant>,
  90       <constant>SD_BUS_CREDS_GID</constant>,
  91       <constant>SD_BUS_CREDS_EGID</constant>,
  92       <constant>SD_BUS_CREDS_SGID</constant>,
  93       <constant>SD_BUS_CREDS_FSGID</constant>,
  94       <constant>SD_BUS_CREDS_SUPPLEMENTARY_GIDS</constant>,
  95       <constant>SD_BUS_CREDS_COMM</constant>,
  96       <constant>SD_BUS_CREDS_TID_COMM</constant>,
  97       <constant>SD_BUS_CREDS_EXE</constant>,
  98       <constant>SD_BUS_CREDS_CMDLINE</constant>,
  99       <constant>SD_BUS_CREDS_CGROUP</constant>,
 100       <constant>SD_BUS_CREDS_UNIT</constant>,
 101       <constant>SD_BUS_CREDS_SLICE</constant>,
 102       <constant>SD_BUS_CREDS_USER_UNIT</constant>,
 103       <constant>SD_BUS_CREDS_USER_SLICE</constant>,
 104       <constant>SD_BUS_CREDS_SESSION</constant>,
 105       <constant>SD_BUS_CREDS_OWNER_UID</constant>,
 106       <constant>SD_BUS_CREDS_EFFECTIVE_CAPS</constant>,
 107       <constant>SD_BUS_CREDS_PERMITTED_CAPS</constant>,
 108       <constant>SD_BUS_CREDS_INHERITABLE_CAPS</constant>,
 109       <constant>SD_BUS_CREDS_BOUNDING_CAPS</constant>,
 110       <constant>SD_BUS_CREDS_SELINUX_CONTEXT</constant>,
 111       <constant>SD_BUS_CREDS_AUDIT_SESSION_ID</constant>,
 112       <constant>SD_BUS_CREDS_AUDIT_LOGIN_UID</constant>,
 113       <constant>SD_BUS_CREDS_TTY</constant>,
 114       <constant>SD_BUS_CREDS_UNIQUE_NAME</constant>,
 115       <constant>SD_BUS_CREDS_WELL_KNOWN_NAMES</constant>,
 116       <constant>SD_BUS_CREDS_DESCRIPTION</constant>,
 117       <constant>SD_BUS_CREDS_AUGMENT</constant>,
 118       <constant>_SD_BUS_CREDS_ALL</constant>
 119     </para>
 120   </refsynopsisdiv>
 121
 122   <refsect1>
 123     <title>Description</title>
 124
 125     <para><function>sd_bus_creds_new_from_pid()</function> creates a
 126     new credentials object and fills it with information about the
 127     process <parameter>pid</parameter>. The pointer to this object
 128     will be stored in the <parameter>ret</parameter> pointer. Note that
 129     credential objects may also be created and retrieved via
 130     <citerefentry><refentrytitle>sd_bus_get_name_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 131     <citerefentry><refentrytitle>sd_bus_get_owner_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 132     and
 133     <citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
 134
 135     <para>The information that will be stored is determined by
 136     <parameter>creds_mask</parameter>. It may contain a subset of ORed
 137     constants <constant>SD_BUS_CREDS_PID</constant>,
 138     <constant>SD_BUS_CREDS_PPID</constant>,
 139     <constant>SD_BUS_CREDS_TID</constant>,
 140     <constant>SD_BUS_CREDS_UID</constant>,
 141     <constant>SD_BUS_CREDS_EUID</constant>,
 142     <constant>SD_BUS_CREDS_SUID</constant>,
 143     <constant>SD_BUS_CREDS_FSUID</constant>,
 144     <constant>SD_BUS_CREDS_GID</constant>,
 145     <constant>SD_BUS_CREDS_EGID</constant>,
 146     <constant>SD_BUS_CREDS_SGID</constant>,
 147     <constant>SD_BUS_CREDS_FSGID</constant>,
 148     <constant>SD_BUS_CREDS_SUPPLEMENTARY_GIDS</constant>,
 149     <constant>SD_BUS_CREDS_COMM</constant>,
 150     <constant>SD_BUS_CREDS_TID_COMM</constant>,
 151     <constant>SD_BUS_CREDS_EXE</constant>,
 152     <constant>SD_BUS_CREDS_CMDLINE</constant>,
 153     <constant>SD_BUS_CREDS_CGROUP</constant>,
 154     <constant>SD_BUS_CREDS_UNIT</constant>,
 155     <constant>SD_BUS_CREDS_SLICE</constant>,
 156     <constant>SD_BUS_CREDS_USER_UNIT</constant>,
 157     <constant>SD_BUS_CREDS_USER_SLICE</constant>,
 158     <constant>SD_BUS_CREDS_SESSION</constant>,
 159     <constant>SD_BUS_CREDS_OWNER_UID</constant>,
 160     <constant>SD_BUS_CREDS_EFFECTIVE_CAPS</constant>,
 161     <constant>SD_BUS_CREDS_PERMITTED_CAPS</constant>,
 162     <constant>SD_BUS_CREDS_INHERITABLE_CAPS</constant>,
 163     <constant>SD_BUS_CREDS_BOUNDING_CAPS</constant>,
 164     <constant>SD_BUS_CREDS_SELINUX_CONTEXT</constant>,
 165     <constant>SD_BUS_CREDS_AUDIT_SESSION_ID</constant>,
 166     <constant>SD_BUS_CREDS_AUDIT_LOGIN_UID</constant>,
 167     <constant>SD_BUS_CREDS_TTY</constant>,
 168     <constant>SD_BUS_CREDS_UNIQUE_NAME</constant>,
 169     <constant>SD_BUS_CREDS_WELL_KNOWN_NAMES</constant>, and
 170     <constant>SD_BUS_CREDS_DESCRIPTION</constant>. Use the special
 171     value <constant>_SD_BUS_CREDS_ALL</constant> to request all
 172     supported fields. The <constant>SD_BUS_CREDS_AUGMENT</constant>
 173     constant may not be ORed into the mask for invocations of
 174     <function>sd_bus_creds_new_from_pid()</function>.</para>
 175
 176     <para>Fields can be retrieved from the credentials object using
 177     <citerefentry><refentrytitle>sd_bus_creds_get_pid</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 178     and other functions which correspond directly to the constants
 179     listed above.</para>
 180
 181     <para>A mask of fields which were actually successfully retrieved
 182     can be retrieved with
 183     <function>sd_bus_creds_get_mask()</function>. If the credentials
 184     object was created with
 185     <function>sd_bus_creds_new_from_pid()</function>, this will be a
 186     subset of fields requested in <parameter>creds_mask</parameter>.
 187     </para>
 188
 189     <para>Similar to <function>sd_bus_creds_get_mask()</function>, the
 190     function <function>sd_bus_creds_get_augmented_mask()</function>
 191     returns a bitmask of field constants. The mask indicates which
 192     credential fields have been retrieved in a non-atomic fashion. For
 193     credential objects created via
 194     <function>sd_bus_creds_new_from_pid()</function>, this mask will be
 195     identical to the mask returned by
 196     <function>sd_bus_creds_get_mask()</function>. However, for
 197     credential objects retrieved via
 198     <function>sd_bus_get_name_creds()</function>, this mask will be set
 199     for the credential fields that could not be determined atomically
 200     at peer connection time, and which were later added by reading
 201     augmenting credential data from
 202     <filename>/proc</filename>. Similarly, for credential objects
 203     retrieved via <function>sd_bus_get_owner_creds()</function>, the
 204     mask is set for the fields that could not be determined atomically
 205     at bus creation time, but have been augmented. Similarly, for
 206     credential objects retrieved via
 207     <function>sd_bus_message_get_creds()</function>, the mask is set
 208     for the fields that could not be determined atomically at message
 209     sending time, but have been augmented. The mask returned by
 210     <function>sd_bus_creds_get_augmented_mask()</function> is always a
 211     subset of (or identical to) the mask returned by
 212     <function>sd_bus_creds_get_mask()</function> for the same
 213     object. The latter call hence returns all credential fields
 214     available in the credential object, the former then marks the
 215     subset of those that have been augmented. Note that augmented
 216     fields are unsuitable for authorization decisions, as they may be
 217     retrieved at different times, thus being subject to races. Hence,
 218     augmented fields should be used exclusively for informational
 219     purposes.
 220     </para>
 221
 222     <para><function>sd_bus_creds_ref()</function> creates a new
 223     reference to the credentials object <parameter>c</parameter>. This
 224     object will not be destroyed until
 225     <function>sd_bus_creds_unref()</function> has been called as many
 226     times plus once more. Once the reference count has dropped to zero,
 227     <parameter>c</parameter> cannot be used anymore, so further
 228     calls to <function>sd_bus_creds_ref(c)</function> or
 229     <function>sd_bus_creds_unref(c)</function> are illegal.</para>
 230
 231     <para><function>sd_bus_creds_unref()</function> destroys a reference
 232     to <parameter>c</parameter>.</para>
 233
 234     <para><function>sd_bus_creds_unrefp()</function> is similar to
 235     <function>sd_bus_creds_unref()</function> but takes a pointer to a
 236     pointer to an <type>sd_bus_creds</type> object. This call is useful in
 237     conjunction with GCC's and LLVM's <ulink
 238     url="https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html">Clean-up
 239     Variable Attribute</ulink>. Note that this function is defined as
 240     inline function.</para>
 241
 242     <para><function>sd_bus_creds_ref()</function>,
 243     <function>sd_bus_creds_unref()</function> and
 244     <function>sd_bus_creds_unrefp()</function> execute no operation if
 245     the passed in bus credentials object is
 246     <constant>NULL</constant>.</para>
 247
 248   </refsect1>
 249
 250   <refsect1>
 251     <title>Return Value</title>
 252
 253     <para>On success, <function>sd_bus_creds_new_from_pid()</function>
 254     returns 0 or a positive integer. On failure, it returns a negative
 255     errno-style error code.</para>
 256
 257     <para><function>sd_bus_creds_get_mask()</function> returns the
 258     mask of successfully acquired fields.</para>
 259
 260     <para><function>sd_bus_creds_get_augmented_mask()</function>
 261     returns the mask of fields that have been augmented from data in
 262     <filename>/proc</filename>, and are thus not suitable for
 263     authorization decisions.</para>
 264
 265     <para><function>sd_bus_creds_ref()</function> always returns the
 266     argument.</para>
 267
 268     <para><function>sd_bus_creds_unref()</function> always returns
 269     <constant>NULL</constant>.</para>
 270   </refsect1>
 271
 272   <refsect1>
 273     <title>Reference ownership</title>
 274
 275     <para>Function <function>sd_bus_creds_new_from_pid()</function>
 276     creates a new object and the caller owns the sole reference. When
 277     not needed anymore, this reference should be destroyed with
 278     <citerefentry><refentrytitle>sd_bus_creds_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 279     </para>
 280   </refsect1>
 281
 282   <refsect1>
 283     <title>Errors</title>
 284
 285     <para>Returned errors may indicate the following problems:</para>
 286
 287     <variablelist>
 288
 289       <varlistentry>
 290         <term><constant>-ESRCH</constant></term>
 291
 292         <listitem><para>Specified <parameter>pid</parameter> could not
 293         be found.</para></listitem>
 294       </varlistentry>
 295
 296       <varlistentry>
 297         <term><constant>-EINVAL</constant></term>
 298
 299         <listitem><para>Specified parameter is invalid
 300         (<constant>NULL</constant> in case of output
 301         parameters).</para></listitem>
 302       </varlistentry>
 303
 304       <varlistentry>
 305         <term><constant>-ENOMEM</constant></term>
 306
 307         <listitem><para>Memory allocation failed.</para></listitem>
 308       </varlistentry>
 309
 310       <varlistentry>
 311         <term><constant>-EOPNOTSUPP</constant></term>
 312
 313         <listitem><para>One of the requested fields is unknown to the local system.</para></listitem>
 314       </varlistentry>
 315     </variablelist>
 316   </refsect1>
 317
 318   <xi:include href="libsystemd-pkgconfig.xml" />
 319
 320   <refsect1>
 321     <title>See Also</title>
 322
 323     <para>
 324       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 325       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 326       <citerefentry><refentrytitle>sd_bus_creds_get_pid</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 327       <citerefentry><refentrytitle>sd_bus_get_name_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 328       <citerefentry><refentrytitle>sd_bus_get_owner_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 329       <citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 330     </para>
 331   </refsect1>
 332
 333 </refentry>