diff --git a/TODO b/TODO
index f848b9741e..0079b35963 100644
--- a/TODO
+++ b/TODO
@@ -181,10 +181,6 @@ Features:
* add bpf-based implementation of devices cgroup controller logic for compat
with cgroupsv2 as supported by newest kernel
-* introduce sd_id128_get_boot_app_specific() which is like
- sd_id128_get_machine_app_specific(). After all on long-running systems both
- IDs have similar properties.
-
* sd-bus: add vtable flag, that may be used to request client creds implicitly
and asynchronously before dispatching the operation
diff --git a/man/rules/meson.build b/man/rules/meson.build
index 99915c5e9f..ddb1c6d521 100644
--- a/man/rules/meson.build
+++ b/man/rules/meson.build
@@ -438,6 +438,7 @@ manpages = [
['sd_id128_get_machine',
'3',
['sd_id128_get_boot',
+ 'sd_id128_get_boot_app_specific',
'sd_id128_get_invocation',
'sd_id128_get_machine_app_specific'],
''],
diff --git a/man/sd_id128_get_machine.xml b/man/sd_id128_get_machine.xml
index 9587aa7d66..8425addd18 100644
--- a/man/sd_id128_get_machine.xml
+++ b/man/sd_id128_get_machine.xml
@@ -22,6 +22,7 @@
sd_id128_get_machine
sd_id128_get_machine_app_specific
sd_id128_get_boot
+ sd_id128_get_boot_app_specific
sd_id128_get_invocation
Retrieve 128-bit IDs
@@ -46,6 +47,12 @@
sd_id128_t *ret
+
+ int sd_id128_get_boot_app_specific
+ sd_id128_t app_id
+ sd_id128_t *ret
+
+
int sd_id128_get_invocation
sd_id128_t *ret
@@ -69,19 +76,25 @@
sd_id128_get_machine(), 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
sd_id128_get_machine() 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 journalctl --new-id128, 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.
+ 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 journalctl --new-id128,
+ 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.
- sd_id128_get_boot() returns the boot ID
- of the executing kernel. This reads and parses the
- /proc/sys/kernel/random/boot_id file exposed
- by the kernel. It is randomly generated early at boot and is
- unique for every running kernel instance. See
- random4
- for more information. This function also internally caches the
- returned ID to make this call a cheap operation.
+ sd_id128_get_boot() returns the boot ID of the executing kernel. This reads and parses
+ the /proc/sys/kernel/random/boot_id file exposed by the kernel. It is randomly generated early
+ at boot and is unique for every running kernel instance. See random4 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 sd_id128_get_machine_app_specific(), see below.
+
+ sd_id128_get_boot_app_specific() is analogous to
+ sd_id128_get_machine_app_specific() 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.
sd_id128_get_invocation() returns the invocation ID of the currently executed
service. In its current implementation, this reads and parses the $INVOCATION_ID environment
@@ -89,10 +102,11 @@
systemd.exec5 for details. The
ID is cached internally. In future a different mechanism to determine the invocation ID may be added.
- Note that sd_id128_get_machine_app_specific(), sd_id128_get_boot()
- and sd_id128_get_invocation() always return UUID v4 compatible IDs.
- sd_id128_get_machine() 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
+ Note that sd_id128_get_machine_app_specific(), sd_id128_get_boot(),
+ sd_id128_get_boot_app_specific(), and sd_id128_get_invocation() always
+ return UUID v4 compatible IDs. sd_id128_get_machine() 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
machine-id5.
For more information about the sd_id128_t
@@ -104,10 +118,12 @@
Return Value
Those calls return 0 on success (in which case ret is filled in),
- or a negative errno-style error code. In particular, sd_id128_get_machine()
- and sd_id128_get_machine_app_specific() return -ENOENT
- if /etc/machine-id is missing, and -ENOMEDIUM if is
- empty or all zeros.
+ or a negative errno-style error code. In particular,
+ sd_id128_get_machine(),
+ sd_id128_get_machine_app_specific(), and
+ sd_id128_get_boot_app_specific() return -ENOENT if
+ /etc/machine-id is missing, and -ENOMEDIUM if is empty
+ or all zeros.
diff --git a/src/libsystemd/libsystemd.sym b/src/libsystemd/libsystemd.sym
index d06e95638e..480ef39c7a 100644
--- a/src/libsystemd/libsystemd.sym
+++ b/src/libsystemd/libsystemd.sym
@@ -648,4 +648,6 @@ global:
sd_hwdb_enumerate;
sd_hwdb_unrefp;
+
+ sd_id128_get_boot_app_specific;
} LIBSYSTEMD_239;
diff --git a/src/libsystemd/sd-id128/sd-id128.c b/src/libsystemd/sd-id128/sd-id128.c
index 9d93732d7e..b7cca832d8 100644
--- a/src/libsystemd/sd-id128/sd-id128.c
+++ b/src/libsystemd/sd-id128/sd-id128.c
@@ -284,19 +284,15 @@ _public_ int sd_id128_randomize(sd_id128_t *ret) {
return 0;
}
-_public_ int sd_id128_get_machine_app_specific(sd_id128_t app_id, sd_id128_t *ret) {
+static int get_app_specific(sd_id128_t base, sd_id128_t app_id, sd_id128_t *ret) {
_cleanup_(khash_unrefp) khash *h = NULL;
- sd_id128_t m, result;
+ sd_id128_t result;
const void *p;
int r;
- assert_return(ret, -EINVAL);
+ assert(ret);
- r = sd_id128_get_machine(&m);
- if (r < 0)
- return r;
-
- r = khash_new_with_key(&h, "hmac(sha256)", &m, sizeof(m));
+ r = khash_new_with_key(&h, "hmac(sha256)", &base, sizeof(base));
if (r < 0)
return r;
@@ -314,3 +310,29 @@ _public_ int sd_id128_get_machine_app_specific(sd_id128_t app_id, sd_id128_t *re
*ret = make_v4_uuid(result);
return 0;
}
+
+_public_ int sd_id128_get_machine_app_specific(sd_id128_t app_id, sd_id128_t *ret) {
+ sd_id128_t id;
+ int r;
+
+ assert_return(ret, -EINVAL);
+
+ r = sd_id128_get_machine(&id);
+ if (r < 0)
+ return r;
+
+ return get_app_specific(id, app_id, ret);
+}
+
+_public_ int sd_id128_get_boot_app_specific(sd_id128_t app_id, sd_id128_t *ret) {
+ sd_id128_t id;
+ int r;
+
+ assert_return(ret, -EINVAL);
+
+ r = sd_id128_get_boot(&id);
+ if (r < 0)
+ return r;
+
+ return get_app_specific(id, app_id, ret);
+}
diff --git a/src/systemd/sd-id128.h b/src/systemd/sd-id128.h
index 143a0ffb5e..78cf9462b0 100644
--- a/src/systemd/sd-id128.h
+++ b/src/systemd/sd-id128.h
@@ -42,6 +42,7 @@ 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_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);