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Commit | Line | Data |
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53e1b683 | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
29206d46 | 2 | |
29206d46 | 3 | #include <sys/file.h> |
ca78ad1d ZJS |
4 | #include <sys/stat.h> |
5 | #include <sys/types.h> | |
29206d46 | 6 | |
98e4fcec | 7 | #include "clean-ipc.h" |
29206d46 LP |
8 | #include "dynamic-user.h" |
9 | #include "fd-util.h" | |
e6a7ec4b | 10 | #include "fileio.h" |
ca78ad1d | 11 | #include "format-util.h" |
29206d46 | 12 | #include "fs-util.h" |
e6a7ec4b | 13 | #include "io-util.h" |
460ec549 | 14 | #include "nscd-flush.h" |
29206d46 LP |
15 | #include "parse-util.h" |
16 | #include "random-util.h" | |
d68c645b | 17 | #include "serialize.h" |
57b7a260 | 18 | #include "socket-util.h" |
29206d46 LP |
19 | #include "stdio-util.h" |
20 | #include "string-util.h" | |
5cfa33e0 | 21 | #include "strv.h" |
98dcb8f4 | 22 | #include "user-record.h" |
29206d46 | 23 | #include "user-util.h" |
29206d46 | 24 | |
29206d46 | 25 | /* Takes a value generated randomly or by hashing and turns it into a UID in the right range */ |
61755fda | 26 | #define UID_CLAMP_INTO_RANGE(rnd) (((uid_t) (rnd) % (DYNAMIC_UID_MAX - DYNAMIC_UID_MIN + 1)) + DYNAMIC_UID_MIN) |
29206d46 | 27 | |
8301aa0b YW |
28 | DEFINE_PRIVATE_TRIVIAL_REF_FUNC(DynamicUser, dynamic_user); |
29 | ||
29206d46 LP |
30 | static DynamicUser* dynamic_user_free(DynamicUser *d) { |
31 | if (!d) | |
32 | return NULL; | |
33 | ||
34 | if (d->manager) | |
35 | (void) hashmap_remove(d->manager->dynamic_users, d->name); | |
36 | ||
37 | safe_close_pair(d->storage_socket); | |
6b430fdb | 38 | return mfree(d); |
29206d46 LP |
39 | } |
40 | ||
3042bbeb | 41 | static int dynamic_user_add(Manager *m, const char *name, int storage_socket[static 2], DynamicUser **ret) { |
33430217 | 42 | DynamicUser *d; |
29206d46 LP |
43 | int r; |
44 | ||
45 | assert(m); | |
46 | assert(name); | |
47 | assert(storage_socket); | |
48 | ||
49 | r = hashmap_ensure_allocated(&m->dynamic_users, &string_hash_ops); | |
50 | if (r < 0) | |
51 | return r; | |
52 | ||
53 | d = malloc0(offsetof(DynamicUser, name) + strlen(name) + 1); | |
54 | if (!d) | |
55 | return -ENOMEM; | |
56 | ||
57 | strcpy(d->name, name); | |
58 | ||
59 | d->storage_socket[0] = storage_socket[0]; | |
60 | d->storage_socket[1] = storage_socket[1]; | |
61 | ||
62 | r = hashmap_put(m->dynamic_users, d->name, d); | |
63 | if (r < 0) { | |
64 | free(d); | |
65 | return r; | |
66 | } | |
67 | ||
68 | d->manager = m; | |
69 | ||
70 | if (ret) | |
71 | *ret = d; | |
72 | ||
73 | return 0; | |
74 | } | |
75 | ||
9da440b1 | 76 | static int dynamic_user_acquire(Manager *m, const char *name, DynamicUser** ret) { |
29206d46 LP |
77 | _cleanup_close_pair_ int storage_socket[2] = { -1, -1 }; |
78 | DynamicUser *d; | |
79 | int r; | |
80 | ||
81 | assert(m); | |
82 | assert(name); | |
83 | ||
84 | /* Return the DynamicUser structure for a specific user name. Note that this won't actually allocate a UID for | |
85 | * it, but just prepare the data structure for it. The UID is allocated only on demand, when it's really | |
86 | * needed, and in the child process we fork off, since allocation involves NSS checks which are not OK to do | |
87 | * from PID 1. To allow the children and PID 1 share information about allocated UIDs we use an anonymous | |
88 | * AF_UNIX/SOCK_DGRAM socket (called the "storage socket") that contains at most one datagram with the | |
89 | * allocated UID number, plus an fd referencing the lock file for the UID | |
90 | * (i.e. /run/systemd/dynamic-uid/$UID). Why involve the socket pair? So that PID 1 and all its children can | |
91 | * share the same storage for the UID and lock fd, simply by inheriting the storage socket fds. The socket pair | |
92 | * may exist in three different states: | |
93 | * | |
94 | * a) no datagram stored. This is the initial state. In this case the dynamic user was never realized. | |
95 | * | |
96 | * b) a datagram containing a UID stored, but no lock fd attached to it. In this case there was already a | |
97 | * statically assigned UID by the same name, which we are reusing. | |
98 | * | |
99 | * c) a datagram containing a UID stored, and a lock fd is attached to it. In this case we allocated a dynamic | |
100 | * UID and locked it in the file system, using the lock fd. | |
101 | * | |
102 | * As PID 1 and various children might access the socket pair simultaneously, and pop the datagram or push it | |
103 | * back in any time, we also maintain a lock on the socket pair. Note one peculiarity regarding locking here: | |
104 | * the UID lock on disk is protected via a BSD file lock (i.e. an fd-bound lock), so that the lock is kept in | |
105 | * place as long as there's a reference to the fd open. The lock on the storage socket pair however is a POSIX | |
106 | * file lock (i.e. a process-bound lock), as all users share the same fd of this (after all it is anonymous, | |
107 | * nobody else could get any access to it except via our own fd) and we want to synchronize access between all | |
108 | * processes that have access to it. */ | |
109 | ||
110 | d = hashmap_get(m->dynamic_users, name); | |
111 | if (d) { | |
288ca7af YW |
112 | if (ret) { |
113 | /* We already have a structure for the dynamic user, let's increase the ref count and reuse it */ | |
114 | d->n_ref++; | |
115 | *ret = d; | |
116 | } | |
29206d46 LP |
117 | return 0; |
118 | } | |
119 | ||
7a8867ab | 120 | if (!valid_user_group_name(name, VALID_USER_ALLOW_NUMERIC)) |
29206d46 LP |
121 | return -EINVAL; |
122 | ||
123 | if (socketpair(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0, storage_socket) < 0) | |
124 | return -errno; | |
125 | ||
126 | r = dynamic_user_add(m, name, storage_socket, &d); | |
127 | if (r < 0) | |
128 | return r; | |
129 | ||
130 | storage_socket[0] = storage_socket[1] = -1; | |
131 | ||
132 | if (ret) { | |
133 | d->n_ref++; | |
134 | *ret = d; | |
135 | } | |
136 | ||
137 | return 1; | |
138 | } | |
139 | ||
fd63e712 LP |
140 | static int make_uid_symlinks(uid_t uid, const char *name, bool b) { |
141 | ||
fbd0b64f | 142 | char path1[STRLEN("/run/systemd/dynamic-uid/direct:") + DECIMAL_STR_MAX(uid_t) + 1]; |
fd63e712 | 143 | const char *path2; |
986a34a6 | 144 | int r = 0, k; |
fd63e712 LP |
145 | |
146 | /* Add direct additional symlinks for direct lookups of dynamic UIDs and their names by userspace code. The | |
147 | * only reason we have this is because dbus-daemon cannot use D-Bus for resolving users and groups (since it | |
148 | * would be its own client then). We hence keep these world-readable symlinks in place, so that the | |
149 | * unprivileged dbus user can read the mappings when it needs them via these symlinks instead of having to go | |
150 | * via the bus. Ideally, we'd use the lock files we keep for this anyway, but we can't since we use BSD locks | |
151 | * on them and as those may be taken by any user with read access we can't make them world-readable. */ | |
152 | ||
153 | xsprintf(path1, "/run/systemd/dynamic-uid/direct:" UID_FMT, uid); | |
986a34a6 ZJS |
154 | if (unlink(path1) < 0 && errno != ENOENT) |
155 | r = -errno; | |
156 | ||
157 | if (b && symlink(name, path1) < 0) { | |
158 | k = log_warning_errno(errno, "Failed to symlink \"%s\": %m", path1); | |
159 | if (r == 0) | |
160 | r = k; | |
fd63e712 LP |
161 | } |
162 | ||
163 | path2 = strjoina("/run/systemd/dynamic-uid/direct:", name); | |
986a34a6 ZJS |
164 | if (unlink(path2) < 0 && errno != ENOENT) { |
165 | k = -errno; | |
166 | if (r == 0) | |
167 | r = k; | |
fd63e712 | 168 | } |
986a34a6 | 169 | |
fbd0b64f | 170 | if (b && symlink(path1 + STRLEN("/run/systemd/dynamic-uid/direct:"), path2) < 0) { |
986a34a6 ZJS |
171 | k = log_warning_errno(errno, "Failed to symlink \"%s\": %m", path2); |
172 | if (r == 0) | |
173 | r = k; | |
fd63e712 LP |
174 | } |
175 | ||
176 | return r; | |
177 | } | |
178 | ||
da50b85a LP |
179 | static int pick_uid(char **suggested_paths, const char *name, uid_t *ret_uid) { |
180 | ||
181 | /* Find a suitable free UID. We use the following strategy to find a suitable UID: | |
182 | * | |
183 | * 1. Initially, we try to read the UID of a number of specified paths. If any of these UIDs works, we use | |
184 | * them. We use in order to increase the chance of UID reuse, if StateDirectory=, CacheDirectory= or | |
d7ef1257 | 185 | * LogsDirectory= are used, as reusing the UID these directories are owned by saves us from having to |
da50b85a LP |
186 | * recursively chown() them to new users. |
187 | * | |
188 | * 2. If that didn't yield a currently unused UID, we hash the user name, and try to use that. This should be | |
189 | * pretty good, as the use ris by default derived from the unit name, and hence the same service and same | |
190 | * user should usually get the same UID as long as our hashing doesn't clash. | |
191 | * | |
192 | * 3. Finally, if that didn't work, we randomly pick UIDs, until we find one that is empty. | |
193 | * | |
194 | * Since the dynamic UID space is relatively small we'll stop trying after 100 iterations, giving up. */ | |
195 | ||
196 | enum { | |
197 | PHASE_SUGGESTED, /* the first phase, reusing directory ownership UIDs */ | |
198 | PHASE_HASHED, /* the second phase, deriving a UID from the username by hashing */ | |
199 | PHASE_RANDOM, /* the last phase, randomly picking UIDs */ | |
200 | } phase = PHASE_SUGGESTED; | |
29206d46 LP |
201 | |
202 | static const uint8_t hash_key[] = { | |
203 | 0x37, 0x53, 0x7e, 0x31, 0xcf, 0xce, 0x48, 0xf5, | |
204 | 0x8a, 0xbb, 0x39, 0x57, 0x8d, 0xd9, 0xec, 0x59 | |
205 | }; | |
206 | ||
da50b85a | 207 | unsigned n_tries = 100, current_suggested = 0; |
29206d46 LP |
208 | int r; |
209 | ||
29206d46 LP |
210 | (void) mkdir("/run/systemd/dynamic-uid", 0755); |
211 | ||
212 | for (;;) { | |
fbd0b64f | 213 | char lock_path[STRLEN("/run/systemd/dynamic-uid/") + DECIMAL_STR_MAX(uid_t) + 1]; |
29206d46 | 214 | _cleanup_close_ int lock_fd = -1; |
da50b85a | 215 | uid_t candidate; |
29206d46 LP |
216 | ssize_t l; |
217 | ||
218 | if (--n_tries <= 0) /* Give up retrying eventually */ | |
219 | return -EBUSY; | |
220 | ||
da50b85a LP |
221 | switch (phase) { |
222 | ||
223 | case PHASE_SUGGESTED: { | |
224 | struct stat st; | |
225 | ||
226 | if (!suggested_paths || !suggested_paths[current_suggested]) { | |
227 | /* We reached the end of the suggested paths list, let's try by hashing the name */ | |
228 | phase = PHASE_HASHED; | |
229 | continue; | |
230 | } | |
231 | ||
232 | if (stat(suggested_paths[current_suggested++], &st) < 0) | |
233 | continue; /* We can't read the UID of this path, but that doesn't matter, just try the next */ | |
234 | ||
235 | candidate = st.st_uid; | |
236 | break; | |
237 | } | |
238 | ||
239 | case PHASE_HASHED: | |
240 | /* A static user by this name does not exist yet. Let's find a free ID then, and use that. We | |
241 | * start with a UID generated as hash from the user name. */ | |
242 | candidate = UID_CLAMP_INTO_RANGE(siphash24(name, strlen(name), hash_key)); | |
243 | ||
244 | /* If this one fails, we should proceed with random tries */ | |
245 | phase = PHASE_RANDOM; | |
246 | break; | |
247 | ||
248 | case PHASE_RANDOM: | |
249 | ||
250 | /* Pick another random UID, and see if that works for us. */ | |
251 | random_bytes(&candidate, sizeof(candidate)); | |
252 | candidate = UID_CLAMP_INTO_RANGE(candidate); | |
253 | break; | |
254 | ||
255 | default: | |
256 | assert_not_reached("unknown phase"); | |
257 | } | |
258 | ||
259 | /* Make sure whatever we picked here actually is in the right range */ | |
61755fda | 260 | if (!uid_is_dynamic(candidate)) |
da50b85a | 261 | continue; |
29206d46 LP |
262 | |
263 | xsprintf(lock_path, "/run/systemd/dynamic-uid/" UID_FMT, candidate); | |
264 | ||
265 | for (;;) { | |
266 | struct stat st; | |
267 | ||
268 | lock_fd = open(lock_path, O_CREAT|O_RDWR|O_NOFOLLOW|O_CLOEXEC|O_NOCTTY, 0600); | |
269 | if (lock_fd < 0) | |
270 | return -errno; | |
271 | ||
272 | r = flock(lock_fd, LOCK_EX|LOCK_NB); /* Try to get a BSD file lock on the UID lock file */ | |
273 | if (r < 0) { | |
3742095b | 274 | if (IN_SET(errno, EBUSY, EAGAIN)) |
29206d46 LP |
275 | goto next; /* already in use */ |
276 | ||
277 | return -errno; | |
278 | } | |
279 | ||
280 | if (fstat(lock_fd, &st) < 0) | |
281 | return -errno; | |
282 | if (st.st_nlink > 0) | |
283 | break; | |
284 | ||
629ff674 | 285 | /* Oh, bummer, we got the lock, but the file was unlinked between the time we opened it and |
29206d46 LP |
286 | * got the lock. Close it, and try again. */ |
287 | lock_fd = safe_close(lock_fd); | |
288 | } | |
289 | ||
290 | /* Some superficial check whether this UID/GID might already be taken by some static user */ | |
98e4fcec LP |
291 | if (getpwuid(candidate) || |
292 | getgrgid((gid_t) candidate) || | |
293 | search_ipc(candidate, (gid_t) candidate) != 0) { | |
29206d46 | 294 | (void) unlink(lock_path); |
da50b85a | 295 | continue; |
29206d46 LP |
296 | } |
297 | ||
298 | /* Let's store the user name in the lock file, so that we can use it for looking up the username for a UID */ | |
299 | l = pwritev(lock_fd, | |
300 | (struct iovec[2]) { | |
e6a7ec4b LP |
301 | IOVEC_INIT_STRING(name), |
302 | IOVEC_INIT((char[1]) { '\n' }, 1), | |
29206d46 LP |
303 | }, 2, 0); |
304 | if (l < 0) { | |
e53c42ca | 305 | r = -errno; |
29206d46 | 306 | (void) unlink(lock_path); |
e53c42ca | 307 | return r; |
29206d46 LP |
308 | } |
309 | ||
310 | (void) ftruncate(lock_fd, l); | |
fd63e712 | 311 | (void) make_uid_symlinks(candidate, name, true); /* also add direct lookup symlinks */ |
29206d46 LP |
312 | |
313 | *ret_uid = candidate; | |
c10d6bdb | 314 | return TAKE_FD(lock_fd); |
29206d46 LP |
315 | |
316 | next: | |
da50b85a | 317 | ; |
29206d46 LP |
318 | } |
319 | } | |
320 | ||
321 | static int dynamic_user_pop(DynamicUser *d, uid_t *ret_uid, int *ret_lock_fd) { | |
322 | uid_t uid = UID_INVALID; | |
e6a7ec4b | 323 | struct iovec iov = IOVEC_INIT(&uid, sizeof(uid)); |
d34673ec | 324 | int lock_fd; |
29206d46 | 325 | ssize_t k; |
29206d46 LP |
326 | |
327 | assert(d); | |
328 | assert(ret_uid); | |
329 | assert(ret_lock_fd); | |
330 | ||
331 | /* Read the UID and lock fd that is stored in the storage AF_UNIX socket. This should be called with the lock | |
332 | * on the socket taken. */ | |
333 | ||
d34673ec | 334 | k = receive_one_fd_iov(d->storage_socket[0], &iov, 1, MSG_DONTWAIT, &lock_fd); |
29206d46 | 335 | if (k < 0) |
d34673ec | 336 | return (int) k; |
29206d46 LP |
337 | |
338 | *ret_uid = uid; | |
339 | *ret_lock_fd = lock_fd; | |
340 | ||
341 | return 0; | |
342 | } | |
343 | ||
344 | static int dynamic_user_push(DynamicUser *d, uid_t uid, int lock_fd) { | |
e6a7ec4b | 345 | struct iovec iov = IOVEC_INIT(&uid, sizeof(uid)); |
29206d46 LP |
346 | |
347 | assert(d); | |
348 | ||
349 | /* Store the UID and lock_fd in the storage socket. This should be called with the socket pair lock taken. */ | |
d34673ec | 350 | return send_one_fd_iov(d->storage_socket[1], lock_fd, &iov, 1, MSG_DONTWAIT); |
29206d46 LP |
351 | } |
352 | ||
fd63e712 | 353 | static void unlink_uid_lock(int lock_fd, uid_t uid, const char *name) { |
fbd0b64f | 354 | char lock_path[STRLEN("/run/systemd/dynamic-uid/") + DECIMAL_STR_MAX(uid_t) + 1]; |
29206d46 LP |
355 | |
356 | if (lock_fd < 0) | |
357 | return; | |
358 | ||
359 | xsprintf(lock_path, "/run/systemd/dynamic-uid/" UID_FMT, uid); | |
fd63e712 LP |
360 | (void) unlink(lock_path); |
361 | ||
362 | (void) make_uid_symlinks(uid, name, false); /* remove direct lookup symlinks */ | |
29206d46 LP |
363 | } |
364 | ||
362d90b7 ZJS |
365 | static int lockfp(int fd, int *fd_lock) { |
366 | if (lockf(fd, F_LOCK, 0) < 0) | |
367 | return -errno; | |
368 | *fd_lock = fd; | |
369 | return 0; | |
370 | } | |
371 | ||
372 | static void unlockfp(int *fd_lock) { | |
373 | if (*fd_lock < 0) | |
374 | return; | |
375 | lockf(*fd_lock, F_ULOCK, 0); | |
376 | *fd_lock = -1; | |
377 | } | |
378 | ||
c2983a7f ZJS |
379 | static int dynamic_user_realize( |
380 | DynamicUser *d, | |
381 | char **suggested_dirs, | |
382 | uid_t *ret_uid, gid_t *ret_gid, | |
383 | bool is_user) { | |
29206d46 | 384 | |
362d90b7 ZJS |
385 | _cleanup_(unlockfp) int storage_socket0_lock = -1; |
386 | _cleanup_close_ int uid_lock_fd = -1; | |
387 | _cleanup_close_ int etc_passwd_lock_fd = -1; | |
c2983a7f ZJS |
388 | uid_t num = UID_INVALID; /* a uid if is_user, and a gid otherwise */ |
389 | gid_t gid = GID_INVALID; /* a gid if is_user, ignored otherwise */ | |
460ec549 | 390 | bool flush_cache = false; |
29206d46 LP |
391 | int r; |
392 | ||
393 | assert(d); | |
c2983a7f ZJS |
394 | assert(is_user == !!ret_uid); |
395 | assert(ret_gid); | |
29206d46 LP |
396 | |
397 | /* Acquire a UID for the user name. This will allocate a UID for the user name if the user doesn't exist | |
398 | * yet. If it already exists its existing UID/GID will be reused. */ | |
399 | ||
362d90b7 ZJS |
400 | r = lockfp(d->storage_socket[0], &storage_socket0_lock); |
401 | if (r < 0) | |
402 | return r; | |
29206d46 | 403 | |
c2983a7f | 404 | r = dynamic_user_pop(d, &num, &uid_lock_fd); |
29206d46 LP |
405 | if (r < 0) { |
406 | int new_uid_lock_fd; | |
407 | uid_t new_uid; | |
408 | ||
409 | if (r != -EAGAIN) | |
362d90b7 | 410 | return r; |
29206d46 LP |
411 | |
412 | /* OK, nothing stored yet, let's try to find something useful. While we are working on this release the | |
413 | * lock however, so that nobody else blocks on our NSS lookups. */ | |
362d90b7 | 414 | unlockfp(&storage_socket0_lock); |
29206d46 LP |
415 | |
416 | /* Let's see if a proper, static user or group by this name exists. Try to take the lock on | |
417 | * /etc/passwd, if that fails with EROFS then /etc is read-only. In that case it's fine if we don't | |
418 | * take the lock, given that users can't be added there anyway in this case. */ | |
419 | etc_passwd_lock_fd = take_etc_passwd_lock(NULL); | |
420 | if (etc_passwd_lock_fd < 0 && etc_passwd_lock_fd != -EROFS) | |
421 | return etc_passwd_lock_fd; | |
422 | ||
423 | /* First, let's parse this as numeric UID */ | |
c2983a7f | 424 | r = parse_uid(d->name, &num); |
29206d46 LP |
425 | if (r < 0) { |
426 | struct passwd *p; | |
427 | struct group *g; | |
428 | ||
9ec655cb YW |
429 | if (is_user) { |
430 | /* OK, this is not a numeric UID. Let's see if there's a user by this name */ | |
431 | p = getpwnam(d->name); | |
c2983a7f ZJS |
432 | if (p) { |
433 | num = p->pw_uid; | |
434 | gid = p->pw_gid; | |
435 | } else { | |
9ec655cb YW |
436 | /* if the user does not exist but the group with the same name exists, refuse operation */ |
437 | g = getgrnam(d->name); | |
438 | if (g) | |
439 | return -EILSEQ; | |
440 | } | |
441 | } else { | |
442 | /* Let's see if there's a group by this name */ | |
443 | g = getgrnam(d->name); | |
444 | if (g) | |
c2983a7f | 445 | num = (uid_t) g->gr_gid; |
9ec655cb YW |
446 | else { |
447 | /* if the group does not exist but the user with the same name exists, refuse operation */ | |
448 | p = getpwnam(d->name); | |
449 | if (p) | |
450 | return -EILSEQ; | |
451 | } | |
29206d46 LP |
452 | } |
453 | } | |
454 | ||
c2983a7f | 455 | if (num == UID_INVALID) { |
29206d46 LP |
456 | /* No static UID assigned yet, excellent. Let's pick a new dynamic one, and lock it. */ |
457 | ||
c2983a7f | 458 | uid_lock_fd = pick_uid(suggested_dirs, d->name, &num); |
29206d46 LP |
459 | if (uid_lock_fd < 0) |
460 | return uid_lock_fd; | |
461 | } | |
462 | ||
463 | /* So, we found a working UID/lock combination. Let's see if we actually still need it. */ | |
362d90b7 ZJS |
464 | r = lockfp(d->storage_socket[0], &storage_socket0_lock); |
465 | if (r < 0) { | |
c2983a7f | 466 | unlink_uid_lock(uid_lock_fd, num, d->name); |
362d90b7 | 467 | return r; |
29206d46 LP |
468 | } |
469 | ||
470 | r = dynamic_user_pop(d, &new_uid, &new_uid_lock_fd); | |
471 | if (r < 0) { | |
472 | if (r != -EAGAIN) { | |
473 | /* OK, something bad happened, let's get rid of the bits we acquired. */ | |
c2983a7f | 474 | unlink_uid_lock(uid_lock_fd, num, d->name); |
362d90b7 | 475 | return r; |
29206d46 LP |
476 | } |
477 | ||
478 | /* Great! Nothing is stored here, still. Store our newly acquired data. */ | |
460ec549 | 479 | flush_cache = true; |
29206d46 LP |
480 | } else { |
481 | /* Hmm, so as it appears there's now something stored in the storage socket. Throw away what we | |
482 | * acquired, and use what's stored now. */ | |
483 | ||
c2983a7f | 484 | unlink_uid_lock(uid_lock_fd, num, d->name); |
29206d46 LP |
485 | safe_close(uid_lock_fd); |
486 | ||
c2983a7f | 487 | num = new_uid; |
29206d46 LP |
488 | uid_lock_fd = new_uid_lock_fd; |
489 | } | |
25a1df7c YW |
490 | } else if (is_user && !uid_is_dynamic(num)) { |
491 | struct passwd *p; | |
492 | ||
493 | /* Statically allocated user may have different uid and gid. So, let's obtain the gid. */ | |
494 | errno = 0; | |
495 | p = getpwuid(num); | |
496 | if (!p) | |
66855de7 | 497 | return errno_or_else(ESRCH); |
25a1df7c YW |
498 | |
499 | gid = p->pw_gid; | |
29206d46 LP |
500 | } |
501 | ||
502 | /* If the UID/GID was already allocated dynamically, push the data we popped out back in. If it was already | |
503 | * allocated statically, push the UID back too, but do not push the lock fd in. If we allocated the UID | |
504 | * dynamically right here, push that in along with the lock fd for it. */ | |
c2983a7f | 505 | r = dynamic_user_push(d, num, uid_lock_fd); |
29206d46 | 506 | if (r < 0) |
362d90b7 | 507 | return r; |
29206d46 | 508 | |
460ec549 LP |
509 | if (flush_cache) { |
510 | /* If we allocated a new dynamic UID, refresh nscd, so that it forgets about potentially cached | |
511 | * negative entries. But let's do so after we release the /etc/passwd lock, so that there's no | |
512 | * potential for nscd wanting to lock that for completing the invalidation. */ | |
513 | etc_passwd_lock_fd = safe_close(etc_passwd_lock_fd); | |
514 | (void) nscd_flush_cache(STRV_MAKE("passwd", "group")); | |
515 | } | |
516 | ||
c2983a7f ZJS |
517 | if (is_user) { |
518 | *ret_uid = num; | |
519 | *ret_gid = gid != GID_INVALID ? gid : num; | |
520 | } else | |
521 | *ret_gid = num; | |
522 | ||
362d90b7 | 523 | return 0; |
29206d46 LP |
524 | } |
525 | ||
f9bfa696 | 526 | int dynamic_user_current(DynamicUser *d, uid_t *ret) { |
362d90b7 | 527 | _cleanup_(unlockfp) int storage_socket0_lock = -1; |
29206d46 LP |
528 | _cleanup_close_ int lock_fd = -1; |
529 | uid_t uid; | |
530 | int r; | |
531 | ||
532 | assert(d); | |
29206d46 LP |
533 | |
534 | /* Get the currently assigned UID for the user, if there's any. This simply pops the data from the storage socket, and pushes it back in right-away. */ | |
535 | ||
362d90b7 ZJS |
536 | r = lockfp(d->storage_socket[0], &storage_socket0_lock); |
537 | if (r < 0) | |
538 | return r; | |
29206d46 LP |
539 | |
540 | r = dynamic_user_pop(d, &uid, &lock_fd); | |
541 | if (r < 0) | |
362d90b7 | 542 | return r; |
29206d46 LP |
543 | |
544 | r = dynamic_user_push(d, uid, lock_fd); | |
545 | if (r < 0) | |
362d90b7 | 546 | return r; |
29206d46 | 547 | |
4bad7eed LP |
548 | if (ret) |
549 | *ret = uid; | |
550 | ||
362d90b7 | 551 | return 0; |
29206d46 LP |
552 | } |
553 | ||
9da440b1 | 554 | static DynamicUser* dynamic_user_unref(DynamicUser *d) { |
29206d46 LP |
555 | if (!d) |
556 | return NULL; | |
557 | ||
558 | /* Note that this doesn't actually release any resources itself. If a dynamic user should be fully destroyed | |
559 | * and its UID released, use dynamic_user_destroy() instead. NB: the dynamic user table may contain entries | |
560 | * with no references, which is commonly the case right before a daemon reload. */ | |
561 | ||
562 | assert(d->n_ref > 0); | |
563 | d->n_ref--; | |
564 | ||
565 | return NULL; | |
566 | } | |
567 | ||
568 | static int dynamic_user_close(DynamicUser *d) { | |
362d90b7 | 569 | _cleanup_(unlockfp) int storage_socket0_lock = -1; |
29206d46 LP |
570 | _cleanup_close_ int lock_fd = -1; |
571 | uid_t uid; | |
572 | int r; | |
573 | ||
574 | /* Release the user ID, by releasing the lock on it, and emptying the storage socket. After this the user is | |
575 | * unrealized again, much like it was after it the DynamicUser object was first allocated. */ | |
576 | ||
362d90b7 ZJS |
577 | r = lockfp(d->storage_socket[0], &storage_socket0_lock); |
578 | if (r < 0) | |
579 | return r; | |
29206d46 LP |
580 | |
581 | r = dynamic_user_pop(d, &uid, &lock_fd); | |
362d90b7 | 582 | if (r == -EAGAIN) |
29206d46 | 583 | /* User wasn't realized yet, nothing to do. */ |
362d90b7 | 584 | return 0; |
29206d46 | 585 | if (r < 0) |
362d90b7 | 586 | return r; |
29206d46 LP |
587 | |
588 | /* This dynamic user was realized and dynamically allocated. In this case, let's remove the lock file. */ | |
fd63e712 | 589 | unlink_uid_lock(lock_fd, uid, d->name); |
460ec549 LP |
590 | |
591 | (void) nscd_flush_cache(STRV_MAKE("passwd", "group")); | |
362d90b7 | 592 | return 1; |
29206d46 LP |
593 | } |
594 | ||
9da440b1 | 595 | static DynamicUser* dynamic_user_destroy(DynamicUser *d) { |
29206d46 LP |
596 | if (!d) |
597 | return NULL; | |
598 | ||
599 | /* Drop a reference to a DynamicUser object, and destroy the user completely if this was the last | |
600 | * reference. This is called whenever a service is shut down and wants its dynamic UID gone. Note that | |
601 | * dynamic_user_unref() is what is called whenever a service is simply freed, for example during a reload | |
602 | * cycle, where the dynamic users should not be destroyed, but our datastructures should. */ | |
603 | ||
604 | dynamic_user_unref(d); | |
605 | ||
606 | if (d->n_ref > 0) | |
607 | return NULL; | |
608 | ||
609 | (void) dynamic_user_close(d); | |
610 | return dynamic_user_free(d); | |
611 | } | |
612 | ||
613 | int dynamic_user_serialize(Manager *m, FILE *f, FDSet *fds) { | |
614 | DynamicUser *d; | |
29206d46 LP |
615 | |
616 | assert(m); | |
617 | assert(f); | |
618 | assert(fds); | |
619 | ||
620 | /* Dump the dynamic user database into the manager serialization, to deal with daemon reloads. */ | |
621 | ||
90e74a66 | 622 | HASHMAP_FOREACH(d, m->dynamic_users) { |
29206d46 LP |
623 | int copy0, copy1; |
624 | ||
625 | copy0 = fdset_put_dup(fds, d->storage_socket[0]); | |
626 | if (copy0 < 0) | |
d68c645b | 627 | return log_error_errno(copy0, "Failed to add dynamic user storage fd to serialization: %m"); |
29206d46 LP |
628 | |
629 | copy1 = fdset_put_dup(fds, d->storage_socket[1]); | |
630 | if (copy1 < 0) | |
d68c645b | 631 | return log_error_errno(copy1, "Failed to add dynamic user storage fd to serialization: %m"); |
29206d46 | 632 | |
d68c645b | 633 | (void) serialize_item_format(f, "dynamic-user", "%s %i %i", d->name, copy0, copy1); |
29206d46 LP |
634 | } |
635 | ||
636 | return 0; | |
637 | } | |
638 | ||
639 | void dynamic_user_deserialize_one(Manager *m, const char *value, FDSet *fds) { | |
640 | _cleanup_free_ char *name = NULL, *s0 = NULL, *s1 = NULL; | |
641 | int r, fd0, fd1; | |
642 | ||
643 | assert(m); | |
644 | assert(value); | |
645 | assert(fds); | |
646 | ||
647 | /* Parse the serialization again, after a daemon reload */ | |
648 | ||
649 | r = extract_many_words(&value, NULL, 0, &name, &s0, &s1, NULL); | |
650 | if (r != 3 || !isempty(value)) { | |
651 | log_debug("Unable to parse dynamic user line."); | |
652 | return; | |
653 | } | |
654 | ||
655 | if (safe_atoi(s0, &fd0) < 0 || !fdset_contains(fds, fd0)) { | |
656 | log_debug("Unable to process dynamic user fd specification."); | |
657 | return; | |
658 | } | |
659 | ||
660 | if (safe_atoi(s1, &fd1) < 0 || !fdset_contains(fds, fd1)) { | |
661 | log_debug("Unable to process dynamic user fd specification."); | |
662 | return; | |
663 | } | |
664 | ||
665 | r = dynamic_user_add(m, name, (int[]) { fd0, fd1 }, NULL); | |
666 | if (r < 0) { | |
667 | log_debug_errno(r, "Failed to add dynamic user: %m"); | |
668 | return; | |
669 | } | |
670 | ||
671 | (void) fdset_remove(fds, fd0); | |
672 | (void) fdset_remove(fds, fd1); | |
673 | } | |
674 | ||
675 | void dynamic_user_vacuum(Manager *m, bool close_user) { | |
676 | DynamicUser *d; | |
29206d46 LP |
677 | |
678 | assert(m); | |
679 | ||
680 | /* Empty the dynamic user database, optionally cleaning up orphaned dynamic users, i.e. destroy and free users | |
681 | * to which no reference exist. This is called after a daemon reload finished, in order to destroy users which | |
682 | * might not be referenced anymore. */ | |
683 | ||
90e74a66 | 684 | HASHMAP_FOREACH(d, m->dynamic_users) { |
29206d46 LP |
685 | if (d->n_ref > 0) |
686 | continue; | |
687 | ||
688 | if (close_user) { | |
689 | log_debug("Removing orphaned dynamic user %s", d->name); | |
690 | (void) dynamic_user_close(d); | |
691 | } | |
692 | ||
693 | dynamic_user_free(d); | |
694 | } | |
695 | } | |
696 | ||
697 | int dynamic_user_lookup_uid(Manager *m, uid_t uid, char **ret) { | |
fbd0b64f | 698 | char lock_path[STRLEN("/run/systemd/dynamic-uid/") + DECIMAL_STR_MAX(uid_t) + 1]; |
29206d46 LP |
699 | _cleanup_free_ char *user = NULL; |
700 | uid_t check_uid; | |
701 | int r; | |
702 | ||
703 | assert(m); | |
704 | assert(ret); | |
705 | ||
61755fda ZJS |
706 | /* A friendly way to translate a dynamic user's UID into a name. */ |
707 | if (!uid_is_dynamic(uid)) | |
29206d46 LP |
708 | return -ESRCH; |
709 | ||
710 | xsprintf(lock_path, "/run/systemd/dynamic-uid/" UID_FMT, uid); | |
711 | r = read_one_line_file(lock_path, &user); | |
a2176045 | 712 | if (IN_SET(r, -ENOENT, 0)) |
29206d46 LP |
713 | return -ESRCH; |
714 | if (r < 0) | |
715 | return r; | |
716 | ||
717 | /* The lock file might be stale, hence let's verify the data before we return it */ | |
718 | r = dynamic_user_lookup_name(m, user, &check_uid); | |
719 | if (r < 0) | |
720 | return r; | |
721 | if (check_uid != uid) /* lock file doesn't match our own idea */ | |
722 | return -ESRCH; | |
723 | ||
ae2a15bc | 724 | *ret = TAKE_PTR(user); |
29206d46 LP |
725 | |
726 | return 0; | |
727 | } | |
728 | ||
729 | int dynamic_user_lookup_name(Manager *m, const char *name, uid_t *ret) { | |
730 | DynamicUser *d; | |
731 | int r; | |
732 | ||
733 | assert(m); | |
734 | assert(name); | |
29206d46 LP |
735 | |
736 | /* A friendly call for translating a dynamic user's name into its UID */ | |
737 | ||
738 | d = hashmap_get(m->dynamic_users, name); | |
739 | if (!d) | |
740 | return -ESRCH; | |
741 | ||
742 | r = dynamic_user_current(d, ret); | |
743 | if (r == -EAGAIN) /* not realized yet? */ | |
744 | return -ESRCH; | |
745 | ||
746 | return r; | |
747 | } | |
748 | ||
749 | int dynamic_creds_acquire(DynamicCreds *creds, Manager *m, const char *user, const char *group) { | |
750 | bool acquired = false; | |
751 | int r; | |
752 | ||
753 | assert(creds); | |
754 | assert(m); | |
755 | ||
756 | /* A DynamicUser object encapsulates an allocation of both a UID and a GID for a specific name. However, some | |
757 | * services use different user and groups. For cases like that there's DynamicCreds containing a pair of user | |
758 | * and group. This call allocates a pair. */ | |
759 | ||
760 | if (!creds->user && user) { | |
761 | r = dynamic_user_acquire(m, user, &creds->user); | |
762 | if (r < 0) | |
763 | return r; | |
764 | ||
765 | acquired = true; | |
766 | } | |
767 | ||
768 | if (!creds->group) { | |
769 | ||
770 | if (creds->user && (!group || streq_ptr(user, group))) | |
771 | creds->group = dynamic_user_ref(creds->user); | |
50152bb1 | 772 | else if (group) { |
29206d46 LP |
773 | r = dynamic_user_acquire(m, group, &creds->group); |
774 | if (r < 0) { | |
775 | if (acquired) | |
776 | creds->user = dynamic_user_unref(creds->user); | |
777 | return r; | |
778 | } | |
779 | } | |
780 | } | |
781 | ||
782 | return 0; | |
783 | } | |
784 | ||
da50b85a | 785 | int dynamic_creds_realize(DynamicCreds *creds, char **suggested_paths, uid_t *uid, gid_t *gid) { |
29206d46 LP |
786 | uid_t u = UID_INVALID; |
787 | gid_t g = GID_INVALID; | |
788 | int r; | |
789 | ||
790 | assert(creds); | |
791 | assert(uid); | |
792 | assert(gid); | |
793 | ||
794 | /* Realize both the referenced user and group */ | |
795 | ||
796 | if (creds->user) { | |
c2983a7f | 797 | r = dynamic_user_realize(creds->user, suggested_paths, &u, &g, true); |
29206d46 LP |
798 | if (r < 0) |
799 | return r; | |
800 | } | |
801 | ||
802 | if (creds->group && creds->group != creds->user) { | |
c2983a7f | 803 | r = dynamic_user_realize(creds->group, suggested_paths, NULL, &g, false); |
29206d46 LP |
804 | if (r < 0) |
805 | return r; | |
c2983a7f | 806 | } |
29206d46 LP |
807 | |
808 | *uid = u; | |
809 | *gid = g; | |
29206d46 LP |
810 | return 0; |
811 | } | |
812 | ||
813 | void dynamic_creds_unref(DynamicCreds *creds) { | |
814 | assert(creds); | |
815 | ||
816 | creds->user = dynamic_user_unref(creds->user); | |
817 | creds->group = dynamic_user_unref(creds->group); | |
818 | } | |
819 | ||
820 | void dynamic_creds_destroy(DynamicCreds *creds) { | |
821 | assert(creds); | |
822 | ||
823 | creds->user = dynamic_user_destroy(creds->user); | |
824 | creds->group = dynamic_user_destroy(creds->group); | |
825 | } |