1 /* SPDX-License-Identifier: LGPL-2.1+ */
11 #include "alloc-util.h"
13 #include "hexdecoct.h"
14 #include "id128-util.h"
19 #include "random-util.h"
20 #include "user-util.h"
23 _public_ char *sd_id128_to_string(sd_id128_t id, char s[SD_ID128_STRING_MAX]) {
26 assert_return(s, NULL);
28 for (n = 0; n < 16; n++) {
29 s[n*2] = hexchar(id.bytes[n] >> 4);
30 s[n*2+1] = hexchar(id.bytes[n] & 0xF);
38 _public_ int sd_id128_from_string(const char s[], sd_id128_t *ret) {
43 assert_return(s, -EINVAL);
45 for (n = 0, i = 0; n < 16;) {
49 /* Is this a GUID? Then be nice, and skip over
54 else if (IN_SET(i, 13, 18, 23)) {
64 a = unhexchar(s[i++]);
68 b = unhexchar(s[i++]);
72 t.bytes[n++] = (a << 4) | b;
75 if (i != (is_guid ? 36 : 32))
86 _public_ int sd_id128_get_machine(sd_id128_t *ret) {
87 static thread_local sd_id128_t saved_machine_id = {};
90 assert_return(ret, -EINVAL);
92 if (sd_id128_is_null(saved_machine_id)) {
93 r = id128_read("/etc/machine-id", ID128_PLAIN, &saved_machine_id);
97 if (sd_id128_is_null(saved_machine_id))
101 *ret = saved_machine_id;
105 _public_ int sd_id128_get_boot(sd_id128_t *ret) {
106 static thread_local sd_id128_t saved_boot_id = {};
109 assert_return(ret, -EINVAL);
111 if (sd_id128_is_null(saved_boot_id)) {
112 r = id128_read("/proc/sys/kernel/random/boot_id", ID128_UUID, &saved_boot_id);
117 *ret = saved_boot_id;
121 static int get_invocation_from_keyring(sd_id128_t *ret) {
123 _cleanup_free_ char *description = NULL;
124 char *d, *p, *g, *u, *e;
132 #define MAX_PERMS ((unsigned long) (KEY_POS_VIEW|KEY_POS_READ|KEY_POS_SEARCH| \
133 KEY_USR_VIEW|KEY_USR_READ|KEY_USR_SEARCH))
137 key = request_key("user", "invocation_id", NULL, 0);
139 /* Keyring support not available? No invocation key stored? */
140 if (IN_SET(errno, ENOSYS, ENOKEY))
147 description = new(char, sz);
151 c = keyctl(KEYCTL_DESCRIBE, key, (unsigned long) description, sz, 0);
155 if ((size_t) c <= sz)
162 /* The kernel returns a final NUL in the string, verify that. */
163 assert(description[c-1] == 0);
165 /* Chop off the final description string */
166 d = strrchr(description, ';');
171 /* Look for the permissions */
172 p = strrchr(description, ';');
177 perms = strtoul(p + 1, &e, 16);
180 if (e == p + 1) /* Read at least one character */
182 if (e != d) /* Must reached the end */
185 if ((perms & ~MAX_PERMS) != 0)
190 /* Look for the group ID */
191 g = strrchr(description, ';');
194 r = parse_gid(g + 1, &gid);
201 /* Look for the user ID */
202 u = strrchr(description, ';');
205 r = parse_uid(u + 1, &uid);
211 c = keyctl(KEYCTL_READ, key, (unsigned long) ret, sizeof(sd_id128_t), 0);
214 if (c != sizeof(sd_id128_t))
220 _public_ int sd_id128_get_invocation(sd_id128_t *ret) {
221 static thread_local sd_id128_t saved_invocation_id = {};
224 assert_return(ret, -EINVAL);
226 if (sd_id128_is_null(saved_invocation_id)) {
228 /* We first try to read the invocation ID from the kernel keyring. This has the benefit that it is not
229 * fakeable by unprivileged code. If the information is not available in the keyring, we use
230 * $INVOCATION_ID but ignore the data if our process was called by less privileged code
231 * (i.e. secure_getenv() instead of getenv()).
233 * The kernel keyring is only relevant for system services (as for user services we don't store the
234 * invocation ID in the keyring, as there'd be no trust benefit in that). The environment variable is
235 * primarily relevant for user services, and sufficiently safe as no privilege boundary is involved. */
237 r = get_invocation_from_keyring(&saved_invocation_id);
244 e = secure_getenv("INVOCATION_ID");
248 r = sd_id128_from_string(e, &saved_invocation_id);
254 *ret = saved_invocation_id;
258 static sd_id128_t make_v4_uuid(sd_id128_t id) {
259 /* Stolen from generate_random_uuid() of drivers/char/random.c
260 * in the kernel sources */
262 /* Set UUID version to 4 --- truly random generation */
263 id.bytes[6] = (id.bytes[6] & 0x0F) | 0x40;
265 /* Set the UUID variant to DCE */
266 id.bytes[8] = (id.bytes[8] & 0x3F) | 0x80;
271 _public_ int sd_id128_randomize(sd_id128_t *ret) {
275 assert_return(ret, -EINVAL);
277 r = acquire_random_bytes(&t, sizeof t, true);
281 /* Turn this into a valid v4 UUID, to be nice. Note that we
282 * only guarantee this for newly generated UUIDs, not for
283 * pre-existing ones. */
285 *ret = make_v4_uuid(t);
289 _public_ int sd_id128_get_machine_app_specific(sd_id128_t app_id, sd_id128_t *ret) {
290 _cleanup_(khash_unrefp) khash *h = NULL;
291 sd_id128_t m, result;
295 assert_return(ret, -EINVAL);
297 r = sd_id128_get_machine(&m);
301 r = khash_new_with_key(&h, "hmac(sha256)", &m, sizeof(m));
305 r = khash_put(h, &app_id, sizeof(app_id));
309 r = khash_digest_data(h, &p);
313 /* We chop off the trailing 16 bytes */
314 memcpy(&result, p, MIN(khash_get_size(h), sizeof(result)));
316 *ret = make_v4_uuid(result);