mirror of
https://github.com/systemd/systemd.git
synced 2024-11-01 17:51:22 +03:00
209 lines
9.7 KiB
XML
209 lines
9.7 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
|
|
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
|
|
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
|
|
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
|
|
|
|
<refentry id="sd_id128_get_machine" xmlns:xi="http://www.w3.org/2001/XInclude">
|
|
|
|
<refentryinfo>
|
|
<title>sd_id128_get_machine</title>
|
|
<productname>systemd</productname>
|
|
</refentryinfo>
|
|
|
|
<refmeta>
|
|
<refentrytitle>sd_id128_get_machine</refentrytitle>
|
|
<manvolnum>3</manvolnum>
|
|
</refmeta>
|
|
|
|
<refnamediv>
|
|
<refname>sd_id128_get_machine</refname>
|
|
<refname>sd_id128_get_machine_app_specific</refname>
|
|
<refname>sd_id128_get_boot</refname>
|
|
<refname>sd_id128_get_boot_app_specific</refname>
|
|
<refname>sd_id128_get_invocation</refname>
|
|
<refpurpose>Retrieve 128-bit IDs</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcsynopsisinfo>#include <systemd/sd-id128.h></funcsynopsisinfo>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_id128_get_machine</function></funcdef>
|
|
<paramdef>sd_id128_t *<parameter>ret</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_id128_get_machine_app_specific</function></funcdef>
|
|
<paramdef>sd_id128_t <parameter>app_id</parameter></paramdef>
|
|
<paramdef>sd_id128_t *<parameter>ret</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_id128_get_boot</function></funcdef>
|
|
<paramdef>sd_id128_t *<parameter>ret</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_id128_get_boot_app_specific</function></funcdef>
|
|
<paramdef>sd_id128_t <parameter>app_id</parameter></paramdef>
|
|
<paramdef>sd_id128_t *<parameter>ret</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_id128_get_invocation</function></funcdef>
|
|
<paramdef>sd_id128_t *<parameter>ret</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsect1>
|
|
<title>Description</title>
|
|
|
|
<para><function>sd_id128_get_machine()</function> returns the machine ID of the executing host. This reads and
|
|
parses the <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
|
file. This function caches the machine ID internally to make retrieving the machine ID a cheap operation. This ID
|
|
may be used wherever a unique identifier for the local system is needed. However, it is recommended to use this ID
|
|
as-is only in trusted environments. In untrusted environments it is recommended to derive an application specific
|
|
ID from this machine ID, in an irreversible (cryptographically secure) way. To make this easy
|
|
<function>sd_id128_get_machine_app_specific()</function> is provided, see below.</para>
|
|
|
|
<para><function>sd_id128_get_machine_app_specific()</function> is similar to
|
|
<function>sd_id128_get_machine()</function>, but retrieves a machine ID that is specific to the application that is
|
|
identified by the indicated application ID. It is recommended to use this function instead of
|
|
<function>sd_id128_get_machine()</function> when passing an ID to untrusted environments, in order to make sure
|
|
that the original machine ID may not be determined externally. This way, the ID used by the application remains
|
|
stable on a given machine, but cannot be easily correlated with IDs used in other applications on the same
|
|
machine. The application-specific ID should be generated via a tool like <command>systemd-id128 new</command>,
|
|
and may be compiled into the application. This function will return the same application-specific ID for each
|
|
combination of machine ID and application ID. Internally, this function calculates HMAC-SHA256 of the application
|
|
ID, keyed by the machine ID.</para>
|
|
|
|
<para><function>sd_id128_get_boot()</function> returns the boot ID of the executing kernel. This reads and parses
|
|
the <filename>/proc/sys/kernel/random/boot_id</filename> file exposed by the kernel. It is randomly generated early
|
|
at boot and is unique for every running kernel instance. See <citerefentry
|
|
project='man-pages'><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more
|
|
information. This function also internally caches the returned ID to make this call a cheap operation. It is
|
|
recommended to use this ID as-is only in trusted environments. In untrusted environments it is recommended to
|
|
derive an application specific ID using <function>sd_id128_get_machine_app_specific()</function>, see below.</para>
|
|
|
|
<para><function>sd_id128_get_boot_app_specific()</function> is analogous to
|
|
<function>sd_id128_get_machine_app_specific()</function> but returns an ID that changes between boots. Some
|
|
machines may be used for a long time without rebooting, hence the boot ID may remain constant for a long time, and
|
|
has properties similar to the machine ID during that time.</para>
|
|
|
|
<para><function>sd_id128_get_invocation()</function> returns the invocation ID of the currently executed
|
|
service. In its current implementation, this reads and parses the <varname>$INVOCATION_ID</varname> environment
|
|
variable that the service manager sets when activating a service, see
|
|
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details. The
|
|
ID is cached internally. In future a different mechanism to determine the invocation ID may be added.</para>
|
|
|
|
<para>Note that <function>sd_id128_get_machine_app_specific()</function>, <function>sd_id128_get_boot()</function>,
|
|
<function>sd_id128_get_boot_app_specific()</function>, and <function>sd_id128_get_invocation()</function> always
|
|
return UUID v4 compatible IDs. <function>sd_id128_get_machine()</function> will also return a UUID v4-compatible
|
|
ID on new installations but might not on older. It is possible to convert the machine ID into a UUID v4-compatible
|
|
one. For more information, see
|
|
<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
|
|
|
|
<para>For more information about the <literal>sd_id128_t</literal>
|
|
type see
|
|
<citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Return Value</title>
|
|
|
|
<para>Those calls return 0 on success (in which case <parameter>ret</parameter> is filled in),
|
|
or a negative errno-style error code.</para>
|
|
|
|
<refsect2>
|
|
<title>Errors</title>
|
|
<para>Returned errors may indicate the following problems:</para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>-ENOENT</constant></term>
|
|
|
|
<listitem><para>Returned by <function>sd_id128_get_machine()</function>,
|
|
<function>sd_id128_get_machine_app_specific()</function>, and
|
|
<function>sd_id128_get_boot_app_specific()</function> when <filename>/etc/machine-id</filename> is
|
|
missing.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><constant>-ENOMEDIUM</constant></term>
|
|
|
|
<listitem><para>Returned by <function>sd_id128_get_machine()</function>,
|
|
<function>sd_id128_get_machine_app_specific()</function>, and
|
|
<function>sd_id128_get_boot_app_specific()</function> when <filename>/etc/machine-id</filename> is
|
|
empty or all zeros.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><constant>-ENXIO</constant></term>
|
|
|
|
<listitem><para>Returned by <function>sd_id128_get_invocation()</function> if no invocation ID is
|
|
set.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><constant>-EIO</constant></term>
|
|
|
|
<listitem><para>Returned by any of the functions described here when the configured value has
|
|
invalid format.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><constant>-EPERM</constant></term>
|
|
|
|
<listitem><para>Requested information could not be retrieved because of insufficient permissions.
|
|
</para></listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect2>
|
|
</refsect1>
|
|
|
|
<xi:include href="libsystemd-pkgconfig.xml" />
|
|
|
|
<refsect1>
|
|
<title>Examples</title>
|
|
|
|
<example>
|
|
<title>Application-specific machine ID</title>
|
|
|
|
<para>First, generate the application ID:</para>
|
|
<programlisting>$ systemd-id128 -p new
|
|
As string:
|
|
c273277323db454ea63bb96e79b53e97
|
|
|
|
As UUID:
|
|
c2732773-23db-454e-a63b-b96e79b53e97
|
|
|
|
As man:sd-id128(3) macro:
|
|
#define MESSAGE_XYZ SD_ID128_MAKE(c2,73,27,73,23,db,45,4e,a6,3b,b9,6e,79,b5,3e,97)
|
|
...
|
|
</programlisting>
|
|
|
|
<para>Then use the new identifier in an example application:</para>
|
|
|
|
<programlisting><xi:include href="id128-app-specific.c" parse="text" /></programlisting>
|
|
</example>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>See Also</title>
|
|
|
|
<para>
|
|
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd-id128</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>sd_id128_randomize</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
|
<citerefentry project='man-pages'><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry>
|
|
</para>
|
|
</refsect1>
|
|
|
|
</refentry>
|