diff options
| -rw-r--r-- | Makefile-man.am | 5 | ||||
| -rw-r--r-- | man/machine-id.xml | 15 | ||||
| -rw-r--r-- | man/sd_id128_get_machine.xml | 65 | ||||
| -rw-r--r-- | src/libsystemd/libsystemd.sym | 5 | ||||
| -rw-r--r-- | src/libsystemd/sd-id128/sd-id128.c | 32 | ||||
| -rw-r--r-- | src/systemd/sd-id128.h | 2 | ||||
| -rw-r--r-- | src/test/test-id128.c | 6 |
7 files changed, 110 insertions, 20 deletions
diff --git a/Makefile-man.am b/Makefile-man.am index 013e0d7967..228e29fc4f 100644 --- a/Makefile-man.am +++ b/Makefile-man.am @@ -397,6 +397,7 @@ MANPAGES_ALIAS += \ man/sd_id128_from_string.3 \ man/sd_id128_get_boot.3 \ man/sd_id128_get_invocation.3 \ + man/sd_id128_get_machine_app_specific.3 \ man/sd_id128_is_null.3 \ man/sd_id128_t.3 \ man/sd_is_mq.3 \ @@ -750,6 +751,7 @@ man/sd_id128_equal.3: man/sd-id128.3 man/sd_id128_from_string.3: man/sd_id128_to_string.3 man/sd_id128_get_boot.3: man/sd_id128_get_machine.3 man/sd_id128_get_invocation.3: man/sd_id128_get_machine.3 +man/sd_id128_get_machine_app_specific.3: man/sd_id128_get_machine.3 man/sd_id128_is_null.3: man/sd-id128.3 man/sd_id128_t.3: man/sd-id128.3 man/sd_is_mq.3: man/sd_is_fifo.3 @@ -1531,6 +1533,9 @@ man/sd_id128_get_boot.html: man/sd_id128_get_machine.html man/sd_id128_get_invocation.html: man/sd_id128_get_machine.html $(html-alias) +man/sd_id128_get_machine_app_specific.html: man/sd_id128_get_machine.html + $(html-alias) + man/sd_id128_is_null.html: man/sd-id128.html $(html-alias) diff --git a/man/machine-id.xml b/man/machine-id.xml index a722649de4..3c261bffcc 100644 --- a/man/machine-id.xml +++ b/man/machine-id.xml @@ -71,13 +71,14 @@ <para>This machine ID adheres to the same format and logic as the D-Bus machine ID.</para> - <para>This ID uniquely identifies the host. It should be considered "confidential", and must not - be exposed in untrusted environments, in particular on the network. If a stable unique - identifier that is tied to the machine is needed for some application, the machine ID or any - part of it must not be used directly. Instead the machine ID should be hashed with a - cryptographic, keyed hash function, using a fixed, application-specific key. That way the ID - will be properly unique, and derived in a constant way from the machine ID but there will be no - way to retrieve the original machine ID from the application-specific one.</para> + <para>This ID uniquely identifies the host. It should be considered "confidential", and must not be exposed in + untrusted environments, in particular on the network. If a stable unique identifier that is tied to the machine is + needed for some application, the machine ID or any part of it must not be used directly. Instead the machine ID + should be hashed with a cryptographic, keyed hash function, using a fixed, application-specific key. That way the + ID will be properly unique, and derived in a constant way from the machine ID but there will be no way to retrieve + the original machine ID from the application-specific one. The + <citerefentry><refentrytitle>sd_id128_get_machine_app_specific</refentrytitle><manvolnum>3</manvolnum></citerefentry> + API provides an implementation of such an algorithm.</para> <para>The <citerefentry><refentrytitle>systemd-machine-id-setup</refentrytitle><manvolnum>1</manvolnum></citerefentry> diff --git a/man/sd_id128_get_machine.xml b/man/sd_id128_get_machine.xml index 9a86c24aed..3938c6d836 100644 --- a/man/sd_id128_get_machine.xml +++ b/man/sd_id128_get_machine.xml @@ -44,6 +44,7 @@ <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_invocation</refname> <refpurpose>Retrieve 128-bit IDs</refpurpose> @@ -59,6 +60,12 @@ </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> @@ -74,11 +81,22 @@ <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.</para> + <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 irreversable (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. 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 @@ -95,10 +113,10 @@ <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_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> + 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> @@ -117,13 +135,36 @@ <refsect1> <title>Notes</title> - <para>The <function>sd_id128_get_machine()</function>, <function>sd_id128_get_boot()</function> and - <function>sd_id128_get_invocation()</function> interfaces are available as a shared library, which can be compiled - and linked to with the <literal>libsystemd</literal> <citerefentry + <para>The <function>sd_id128_get_machine()</function>, <function>sd_id128_get_machine_app_specific()</function> + <function>sd_id128_get_boot()</function> and <function>sd_id128_get_invocation()</function> interfaces are + available as a shared library, which can be compiled and linked to with the + <literal>libsystemd</literal> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> file.</para> </refsect1> <refsect1> + <title>Examples</title> + + <example> + <title>Application-specific machine ID</title> + + <para>Here's a simple example for an application specific machine ID:</para> + + <programlisting>#include <systemd/sd-id128.h> +#include <stdio.h> + +#define OUR_APPLICATION_ID SD_ID128_MAKE(c2,73,27,73,23,db,45,4e,a6,3b,b9,6e,79,b5,3e,97) + +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> + </example> + </refsect1> + + <refsect1> <title>See Also</title> <para> diff --git a/src/libsystemd/libsystemd.sym b/src/libsystemd/libsystemd.sym index d48ef6bbe2..46c4dac7d7 100644 --- a/src/libsystemd/libsystemd.sym +++ b/src/libsystemd/libsystemd.sym @@ -511,3 +511,8 @@ global: sd_bus_get_exit_on_disconnect; sd_id128_get_invocation; } LIBSYSTEMD_231; + +LIBSYSTEMD_233 { +global: + sd_id128_get_machine_app_specific; +} LIBSYSTEMD_232; diff --git a/src/libsystemd/sd-id128/sd-id128.c b/src/libsystemd/sd-id128/sd-id128.c index d4450c70a0..0d673ba655 100644 --- a/src/libsystemd/sd-id128/sd-id128.c +++ b/src/libsystemd/sd-id128/sd-id128.c @@ -27,6 +27,7 @@ #include "hexdecoct.h" #include "id128-util.h" #include "io-util.h" +#include "khash.h" #include "macro.h" #include "random-util.h" #include "util.h" @@ -181,3 +182,34 @@ _public_ int sd_id128_randomize(sd_id128_t *ret) { *ret = make_v4_uuid(t); return 0; } + +_public_ int sd_id128_get_machine_app_specific(sd_id128_t app_id, sd_id128_t *ret) { + _cleanup_(khash_unrefp) khash *h = NULL; + sd_id128_t m, result; + const void *p; + int r; + + assert_return(ret, -EINVAL); + + r = sd_id128_get_machine(&m); + if (r < 0) + return r; + + r = khash_new_with_key(&h, "hmac(sha256)", &m, sizeof(m)); + if (r < 0) + return r; + + r = khash_put(h, &app_id, sizeof(app_id)); + if (r < 0) + return r; + + r = khash_digest_data(h, &p); + if (r < 0) + return r; + + /* We chop off the trailing 16 bytes */ + memcpy(&result, p, MIN(khash_get_size(h), sizeof(result))); + + *ret = make_v4_uuid(result); + return 0; +} diff --git a/src/systemd/sd-id128.h b/src/systemd/sd-id128.h index ee011b1861..6cc8e4ac0e 100644 --- a/src/systemd/sd-id128.h +++ b/src/systemd/sd-id128.h @@ -39,12 +39,12 @@ union sd_id128 { #define SD_ID128_STRING_MAX 33 char *sd_id128_to_string(sd_id128_t id, char s[SD_ID128_STRING_MAX]); - int sd_id128_from_string(const char *s, sd_id128_t *ret); int sd_id128_randomize(sd_id128_t *ret); int sd_id128_get_machine(sd_id128_t *ret); +int sd_id128_get_machine_app_specific(sd_id128_t app_id, sd_id128_t *ret); int sd_id128_get_boot(sd_id128_t *ret); int sd_id128_get_invocation(sd_id128_t *ret); diff --git a/src/test/test-id128.c b/src/test/test-id128.c index 1c8e5549da..ab5a111ba9 100644 --- a/src/test/test-id128.c +++ b/src/test/test-id128.c @@ -153,5 +153,11 @@ int main(int argc, char *argv[]) { assert_se(id128_read_fd(fd, ID128_UUID, &id2) >= 0); assert_se(sd_id128_equal(id, id2)); + assert_se(sd_id128_get_machine_app_specific(SD_ID128_MAKE(f0,3d,aa,eb,1c,33,4b,43,a7,32,17,29,44,bf,77,2e), &id) >= 0); + assert_se(sd_id128_get_machine_app_specific(SD_ID128_MAKE(f0,3d,aa,eb,1c,33,4b,43,a7,32,17,29,44,bf,77,2e), &id2) >= 0); + assert_se(sd_id128_equal(id, id2)); + assert_se(sd_id128_get_machine_app_specific(SD_ID128_MAKE(51,df,0b,4b,c3,b0,4c,97,80,e2,99,b9,8c,a3,73,b8), &id2) >= 0); + assert_se(!sd_id128_equal(id, id2)); + return 0; } |