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Diffstat (limited to 'man/sd_id128_get_machine.xml')
-rw-r--r-- | man/sd_id128_get_machine.xml | 82 |
1 files changed, 51 insertions, 31 deletions
diff --git a/man/sd_id128_get_machine.xml b/man/sd_id128_get_machine.xml index 954fd2e6a7..0884838324 100644 --- a/man/sd_id128_get_machine.xml +++ b/man/sd_id128_get_machine.xml @@ -22,6 +22,7 @@ <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> @@ -47,6 +48,12 @@ </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> @@ -69,19 +76,25 @@ <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. The application-specific ID should be generated via - a tool like <command>journalctl --new-id128</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.</para> + 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 @@ -89,10 +102,11 @@ <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> - 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 + <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> @@ -104,10 +118,12 @@ <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. In particular, <function>sd_id128_get_machine()</function> - and <function>sd_id128_get_machine_app_specific()</function> return <constant>-ENOENT</constant> - if <filename>/etc/machine-id</filename> is missing, and <constant>-ENOMEDIUM</constant> if is - empty or all zeros.</para> + or a negative errno-style error code. In particular, + <function>sd_id128_get_machine()</function>, + <function>sd_id128_get_machine_app_specific()</function>, and + <function>sd_id128_get_boot_app_specific()</function> return <constant>-ENOENT</constant> if + <filename>/etc/machine-id</filename> is missing, and <constant>-ENOMEDIUM</constant> if is empty + or all zeros.</para> </refsect1> <xi:include href="libsystemd-pkgconfig.xml" /> @@ -118,19 +134,22 @@ <example> <title>Application-specific machine ID</title> - <para>Here's a simple example for an application specific machine ID:</para> + <para>First, generate the application ID:</para> + <programlisting>$ systemd-id128 -p new +As string: +c273277323db454ea63bb96e79b53e97 + +As UUID: +c2732773-23db-454e-a63b-b96e79b53e97 - <programlisting>#include <systemd/sd-id128.h> -#include <stdio.h> +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> -#define OUR_APPLICATION_ID SD_ID128_MAKE(c2,73,27,73,23,db,45,4e,a6,3b,b9,6e,79,b5,3e,97) + <para>Then use the new identifier in an example application:</para> -int main(int argc, char *argv[]) { - sd_id128_t id; - sd_id128_get_machine_app_specific(OUR_APPLICATION_ID, &id); - printf("Our application ID: " SD_ID128_FORMAT_STR "\n", SD_ID128_FORMAT_VAL(id)); - return 0; -}</programlisting> + <programlisting><xi:include href="id128-app-specific.c" parse="text" /></programlisting> </example> </refsect1> @@ -139,6 +158,7 @@ int main(int argc, char *argv[]) { <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>, |