]>
Commit | Line | Data |
---|---|---|
db9ecf05 | 1 | /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
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" |
b4cbfa5f | 14 | #include "lock-util.h" |
460ec549 | 15 | #include "nscd-flush.h" |
29206d46 LP |
16 | #include "parse-util.h" |
17 | #include "random-util.h" | |
d68c645b | 18 | #include "serialize.h" |
57b7a260 | 19 | #include "socket-util.h" |
29206d46 LP |
20 | #include "stdio-util.h" |
21 | #include "string-util.h" | |
5cfa33e0 | 22 | #include "strv.h" |
b085d224 | 23 | #include "uid-alloc-range.h" |
29206d46 | 24 | #include "user-util.h" |
29206d46 | 25 | |
29206d46 | 26 | /* Takes a value generated randomly or by hashing and turns it into a UID in the right range */ |
61755fda | 27 | #define UID_CLAMP_INTO_RANGE(rnd) (((uid_t) (rnd) % (DYNAMIC_UID_MAX - DYNAMIC_UID_MIN + 1)) + DYNAMIC_UID_MIN) |
29206d46 | 28 | |
8301aa0b YW |
29 | DEFINE_PRIVATE_TRIVIAL_REF_FUNC(DynamicUser, dynamic_user); |
30 | ||
29206d46 LP |
31 | static DynamicUser* dynamic_user_free(DynamicUser *d) { |
32 | if (!d) | |
33 | return NULL; | |
34 | ||
35 | if (d->manager) | |
36 | (void) hashmap_remove(d->manager->dynamic_users, d->name); | |
37 | ||
38 | safe_close_pair(d->storage_socket); | |
6b430fdb | 39 | return mfree(d); |
29206d46 LP |
40 | } |
41 | ||
3042bbeb | 42 | static int dynamic_user_add(Manager *m, const char *name, int storage_socket[static 2], DynamicUser **ret) { |
33430217 | 43 | DynamicUser *d; |
29206d46 LP |
44 | int r; |
45 | ||
46 | assert(m); | |
47 | assert(name); | |
48 | assert(storage_socket); | |
49 | ||
50 | r = hashmap_ensure_allocated(&m->dynamic_users, &string_hash_ops); | |
51 | if (r < 0) | |
52 | return r; | |
53 | ||
54 | d = malloc0(offsetof(DynamicUser, name) + strlen(name) + 1); | |
55 | if (!d) | |
56 | return -ENOMEM; | |
57 | ||
58 | strcpy(d->name, name); | |
59 | ||
60 | d->storage_socket[0] = storage_socket[0]; | |
61 | d->storage_socket[1] = storage_socket[1]; | |
62 | ||
63 | r = hashmap_put(m->dynamic_users, d->name, d); | |
64 | if (r < 0) { | |
65 | free(d); | |
66 | return r; | |
67 | } | |
68 | ||
69 | d->manager = m; | |
70 | ||
71 | if (ret) | |
72 | *ret = d; | |
73 | ||
74 | return 0; | |
75 | } | |
76 | ||
9da440b1 | 77 | static int dynamic_user_acquire(Manager *m, const char *name, DynamicUser** ret) { |
19ee48a6 | 78 | _cleanup_close_pair_ int storage_socket[2] = PIPE_EBADF; |
29206d46 LP |
79 | DynamicUser *d; |
80 | int r; | |
81 | ||
82 | assert(m); | |
83 | assert(name); | |
84 | ||
85 | /* Return the DynamicUser structure for a specific user name. Note that this won't actually allocate a UID for | |
86 | * it, but just prepare the data structure for it. The UID is allocated only on demand, when it's really | |
87 | * needed, and in the child process we fork off, since allocation involves NSS checks which are not OK to do | |
88 | * from PID 1. To allow the children and PID 1 share information about allocated UIDs we use an anonymous | |
89 | * AF_UNIX/SOCK_DGRAM socket (called the "storage socket") that contains at most one datagram with the | |
90 | * allocated UID number, plus an fd referencing the lock file for the UID | |
91 | * (i.e. /run/systemd/dynamic-uid/$UID). Why involve the socket pair? So that PID 1 and all its children can | |
92 | * share the same storage for the UID and lock fd, simply by inheriting the storage socket fds. The socket pair | |
93 | * may exist in three different states: | |
94 | * | |
95 | * a) no datagram stored. This is the initial state. In this case the dynamic user was never realized. | |
96 | * | |
97 | * b) a datagram containing a UID stored, but no lock fd attached to it. In this case there was already a | |
98 | * statically assigned UID by the same name, which we are reusing. | |
99 | * | |
100 | * c) a datagram containing a UID stored, and a lock fd is attached to it. In this case we allocated a dynamic | |
101 | * UID and locked it in the file system, using the lock fd. | |
102 | * | |
103 | * As PID 1 and various children might access the socket pair simultaneously, and pop the datagram or push it | |
104 | * back in any time, we also maintain a lock on the socket pair. Note one peculiarity regarding locking here: | |
105 | * 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 | |
106 | * place as long as there's a reference to the fd open. The lock on the storage socket pair however is a POSIX | |
107 | * file lock (i.e. a process-bound lock), as all users share the same fd of this (after all it is anonymous, | |
108 | * nobody else could get any access to it except via our own fd) and we want to synchronize access between all | |
109 | * processes that have access to it. */ | |
110 | ||
111 | d = hashmap_get(m->dynamic_users, name); | |
112 | if (d) { | |
288ca7af YW |
113 | if (ret) { |
114 | /* We already have a structure for the dynamic user, let's increase the ref count and reuse it */ | |
115 | d->n_ref++; | |
116 | *ret = d; | |
117 | } | |
29206d46 LP |
118 | return 0; |
119 | } | |
120 | ||
7a8867ab | 121 | if (!valid_user_group_name(name, VALID_USER_ALLOW_NUMERIC)) |
29206d46 LP |
122 | return -EINVAL; |
123 | ||
124 | if (socketpair(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0, storage_socket) < 0) | |
125 | return -errno; | |
126 | ||
127 | r = dynamic_user_add(m, name, storage_socket, &d); | |
128 | if (r < 0) | |
129 | return r; | |
130 | ||
5bb1d7fb | 131 | storage_socket[0] = storage_socket[1] = -EBADF; |
29206d46 LP |
132 | |
133 | if (ret) { | |
134 | d->n_ref++; | |
135 | *ret = d; | |
136 | } | |
137 | ||
138 | return 1; | |
139 | } | |
140 | ||
fd63e712 LP |
141 | static int make_uid_symlinks(uid_t uid, const char *name, bool b) { |
142 | ||
fbd0b64f | 143 | char path1[STRLEN("/run/systemd/dynamic-uid/direct:") + DECIMAL_STR_MAX(uid_t) + 1]; |
fd63e712 | 144 | const char *path2; |
986a34a6 | 145 | int r = 0, k; |
fd63e712 LP |
146 | |
147 | /* Add direct additional symlinks for direct lookups of dynamic UIDs and their names by userspace code. The | |
148 | * only reason we have this is because dbus-daemon cannot use D-Bus for resolving users and groups (since it | |
149 | * would be its own client then). We hence keep these world-readable symlinks in place, so that the | |
150 | * unprivileged dbus user can read the mappings when it needs them via these symlinks instead of having to go | |
151 | * via the bus. Ideally, we'd use the lock files we keep for this anyway, but we can't since we use BSD locks | |
152 | * on them and as those may be taken by any user with read access we can't make them world-readable. */ | |
153 | ||
154 | xsprintf(path1, "/run/systemd/dynamic-uid/direct:" UID_FMT, uid); | |
986a34a6 ZJS |
155 | if (unlink(path1) < 0 && errno != ENOENT) |
156 | r = -errno; | |
157 | ||
158 | if (b && symlink(name, path1) < 0) { | |
159 | k = log_warning_errno(errno, "Failed to symlink \"%s\": %m", path1); | |
160 | if (r == 0) | |
161 | r = k; | |
fd63e712 LP |
162 | } |
163 | ||
164 | path2 = strjoina("/run/systemd/dynamic-uid/direct:", name); | |
986a34a6 ZJS |
165 | if (unlink(path2) < 0 && errno != ENOENT) { |
166 | k = -errno; | |
167 | if (r == 0) | |
168 | r = k; | |
fd63e712 | 169 | } |
986a34a6 | 170 | |
fbd0b64f | 171 | if (b && symlink(path1 + STRLEN("/run/systemd/dynamic-uid/direct:"), path2) < 0) { |
986a34a6 ZJS |
172 | k = log_warning_errno(errno, "Failed to symlink \"%s\": %m", path2); |
173 | if (r == 0) | |
174 | r = k; | |
fd63e712 LP |
175 | } |
176 | ||
177 | return r; | |
178 | } | |
179 | ||
da50b85a LP |
180 | static int pick_uid(char **suggested_paths, const char *name, uid_t *ret_uid) { |
181 | ||
182 | /* Find a suitable free UID. We use the following strategy to find a suitable UID: | |
183 | * | |
184 | * 1. Initially, we try to read the UID of a number of specified paths. If any of these UIDs works, we use | |
185 | * them. We use in order to increase the chance of UID reuse, if StateDirectory=, CacheDirectory= or | |
d7ef1257 | 186 | * LogsDirectory= are used, as reusing the UID these directories are owned by saves us from having to |
da50b85a LP |
187 | * recursively chown() them to new users. |
188 | * | |
189 | * 2. If that didn't yield a currently unused UID, we hash the user name, and try to use that. This should be | |
190 | * pretty good, as the use ris by default derived from the unit name, and hence the same service and same | |
191 | * user should usually get the same UID as long as our hashing doesn't clash. | |
192 | * | |
193 | * 3. Finally, if that didn't work, we randomly pick UIDs, until we find one that is empty. | |
194 | * | |
195 | * Since the dynamic UID space is relatively small we'll stop trying after 100 iterations, giving up. */ | |
196 | ||
197 | enum { | |
198 | PHASE_SUGGESTED, /* the first phase, reusing directory ownership UIDs */ | |
199 | PHASE_HASHED, /* the second phase, deriving a UID from the username by hashing */ | |
200 | PHASE_RANDOM, /* the last phase, randomly picking UIDs */ | |
201 | } phase = PHASE_SUGGESTED; | |
29206d46 LP |
202 | |
203 | static const uint8_t hash_key[] = { | |
204 | 0x37, 0x53, 0x7e, 0x31, 0xcf, 0xce, 0x48, 0xf5, | |
205 | 0x8a, 0xbb, 0x39, 0x57, 0x8d, 0xd9, 0xec, 0x59 | |
206 | }; | |
207 | ||
da50b85a | 208 | unsigned n_tries = 100, current_suggested = 0; |
29206d46 LP |
209 | int r; |
210 | ||
29206d46 LP |
211 | (void) mkdir("/run/systemd/dynamic-uid", 0755); |
212 | ||
213 | for (;;) { | |
fbd0b64f | 214 | char lock_path[STRLEN("/run/systemd/dynamic-uid/") + DECIMAL_STR_MAX(uid_t) + 1]; |
254d1313 | 215 | _cleanup_close_ int lock_fd = -EBADF; |
da50b85a | 216 | uid_t candidate; |
29206d46 LP |
217 | ssize_t l; |
218 | ||
219 | if (--n_tries <= 0) /* Give up retrying eventually */ | |
220 | return -EBUSY; | |
221 | ||
da50b85a LP |
222 | switch (phase) { |
223 | ||
224 | case PHASE_SUGGESTED: { | |
225 | struct stat st; | |
226 | ||
227 | if (!suggested_paths || !suggested_paths[current_suggested]) { | |
228 | /* We reached the end of the suggested paths list, let's try by hashing the name */ | |
229 | phase = PHASE_HASHED; | |
230 | continue; | |
231 | } | |
232 | ||
233 | if (stat(suggested_paths[current_suggested++], &st) < 0) | |
234 | continue; /* We can't read the UID of this path, but that doesn't matter, just try the next */ | |
235 | ||
236 | candidate = st.st_uid; | |
237 | break; | |
238 | } | |
239 | ||
240 | case PHASE_HASHED: | |
241 | /* A static user by this name does not exist yet. Let's find a free ID then, and use that. We | |
242 | * start with a UID generated as hash from the user name. */ | |
243 | candidate = UID_CLAMP_INTO_RANGE(siphash24(name, strlen(name), hash_key)); | |
244 | ||
245 | /* If this one fails, we should proceed with random tries */ | |
246 | phase = PHASE_RANDOM; | |
247 | break; | |
248 | ||
249 | case PHASE_RANDOM: | |
250 | ||
251 | /* Pick another random UID, and see if that works for us. */ | |
252 | random_bytes(&candidate, sizeof(candidate)); | |
253 | candidate = UID_CLAMP_INTO_RANGE(candidate); | |
254 | break; | |
255 | ||
256 | default: | |
04499a70 | 257 | assert_not_reached(); |
da50b85a LP |
258 | } |
259 | ||
260 | /* Make sure whatever we picked here actually is in the right range */ | |
61755fda | 261 | if (!uid_is_dynamic(candidate)) |
da50b85a | 262 | continue; |
29206d46 LP |
263 | |
264 | xsprintf(lock_path, "/run/systemd/dynamic-uid/" UID_FMT, candidate); | |
265 | ||
266 | for (;;) { | |
267 | struct stat st; | |
268 | ||
269 | lock_fd = open(lock_path, O_CREAT|O_RDWR|O_NOFOLLOW|O_CLOEXEC|O_NOCTTY, 0600); | |
270 | if (lock_fd < 0) | |
271 | return -errno; | |
272 | ||
273 | r = flock(lock_fd, LOCK_EX|LOCK_NB); /* Try to get a BSD file lock on the UID lock file */ | |
274 | if (r < 0) { | |
3742095b | 275 | if (IN_SET(errno, EBUSY, EAGAIN)) |
29206d46 LP |
276 | goto next; /* already in use */ |
277 | ||
278 | return -errno; | |
279 | } | |
280 | ||
281 | if (fstat(lock_fd, &st) < 0) | |
282 | return -errno; | |
283 | if (st.st_nlink > 0) | |
284 | break; | |
285 | ||
629ff674 | 286 | /* Oh, bummer, we got the lock, but the file was unlinked between the time we opened it and |
29206d46 LP |
287 | * got the lock. Close it, and try again. */ |
288 | lock_fd = safe_close(lock_fd); | |
289 | } | |
290 | ||
291 | /* Some superficial check whether this UID/GID might already be taken by some static user */ | |
98e4fcec LP |
292 | if (getpwuid(candidate) || |
293 | getgrgid((gid_t) candidate) || | |
294 | search_ipc(candidate, (gid_t) candidate) != 0) { | |
29206d46 | 295 | (void) unlink(lock_path); |
da50b85a | 296 | continue; |
29206d46 LP |
297 | } |
298 | ||
299 | /* Let's store the user name in the lock file, so that we can use it for looking up the username for a UID */ | |
300 | l = pwritev(lock_fd, | |
301 | (struct iovec[2]) { | |
ce16d177 YW |
302 | IOVEC_MAKE_STRING(name), |
303 | IOVEC_MAKE((char[1]) { '\n' }, 1), | |
29206d46 LP |
304 | }, 2, 0); |
305 | if (l < 0) { | |
e53c42ca | 306 | r = -errno; |
29206d46 | 307 | (void) unlink(lock_path); |
e53c42ca | 308 | return r; |
29206d46 LP |
309 | } |
310 | ||
311 | (void) ftruncate(lock_fd, l); | |
fd63e712 | 312 | (void) make_uid_symlinks(candidate, name, true); /* also add direct lookup symlinks */ |
29206d46 LP |
313 | |
314 | *ret_uid = candidate; | |
c10d6bdb | 315 | return TAKE_FD(lock_fd); |
29206d46 LP |
316 | |
317 | next: | |
da50b85a | 318 | ; |
29206d46 LP |
319 | } |
320 | } | |
321 | ||
322 | static int dynamic_user_pop(DynamicUser *d, uid_t *ret_uid, int *ret_lock_fd) { | |
323 | uid_t uid = UID_INVALID; | |
ce16d177 | 324 | struct iovec iov = IOVEC_MAKE(&uid, sizeof(uid)); |
d34673ec | 325 | int lock_fd; |
29206d46 | 326 | ssize_t k; |
29206d46 LP |
327 | |
328 | assert(d); | |
329 | assert(ret_uid); | |
330 | assert(ret_lock_fd); | |
331 | ||
8b98cfb7 ZJS |
332 | /* Read the UID and lock fd that is stored in the storage AF_UNIX socket. This should be called with |
333 | * the lock on the socket taken. */ | |
29206d46 | 334 | |
d34673ec | 335 | k = receive_one_fd_iov(d->storage_socket[0], &iov, 1, MSG_DONTWAIT, &lock_fd); |
29206d46 | 336 | if (k < 0) |
d34673ec | 337 | return (int) k; |
29206d46 LP |
338 | |
339 | *ret_uid = uid; | |
340 | *ret_lock_fd = lock_fd; | |
341 | ||
342 | return 0; | |
343 | } | |
344 | ||
345 | static int dynamic_user_push(DynamicUser *d, uid_t uid, int lock_fd) { | |
ce16d177 | 346 | struct iovec iov = IOVEC_MAKE(&uid, sizeof(uid)); |
29206d46 LP |
347 | |
348 | assert(d); | |
349 | ||
350 | /* Store the UID and lock_fd in the storage socket. This should be called with the socket pair lock taken. */ | |
d34673ec | 351 | return send_one_fd_iov(d->storage_socket[1], lock_fd, &iov, 1, MSG_DONTWAIT); |
29206d46 LP |
352 | } |
353 | ||
fd63e712 | 354 | static void unlink_uid_lock(int lock_fd, uid_t uid, const char *name) { |
fbd0b64f | 355 | char lock_path[STRLEN("/run/systemd/dynamic-uid/") + DECIMAL_STR_MAX(uid_t) + 1]; |
29206d46 LP |
356 | |
357 | if (lock_fd < 0) | |
358 | return; | |
359 | ||
360 | xsprintf(lock_path, "/run/systemd/dynamic-uid/" UID_FMT, uid); | |
fd63e712 LP |
361 | (void) unlink(lock_path); |
362 | ||
363 | (void) make_uid_symlinks(uid, name, false); /* remove direct lookup symlinks */ | |
29206d46 LP |
364 | } |
365 | ||
c2983a7f ZJS |
366 | static int dynamic_user_realize( |
367 | DynamicUser *d, | |
368 | char **suggested_dirs, | |
369 | uid_t *ret_uid, gid_t *ret_gid, | |
370 | bool is_user) { | |
29206d46 | 371 | |
254d1313 ZJS |
372 | _cleanup_close_ int uid_lock_fd = -EBADF; |
373 | _cleanup_close_ int etc_passwd_lock_fd = -EBADF; | |
c2983a7f ZJS |
374 | uid_t num = UID_INVALID; /* a uid if is_user, and a gid otherwise */ |
375 | gid_t gid = GID_INVALID; /* a gid if is_user, ignored otherwise */ | |
460ec549 | 376 | bool flush_cache = false; |
29206d46 LP |
377 | int r; |
378 | ||
379 | assert(d); | |
c2983a7f ZJS |
380 | assert(is_user == !!ret_uid); |
381 | assert(ret_gid); | |
29206d46 LP |
382 | |
383 | /* Acquire a UID for the user name. This will allocate a UID for the user name if the user doesn't exist | |
384 | * yet. If it already exists its existing UID/GID will be reused. */ | |
385 | ||
1fe15cb7 | 386 | r = posix_lock(d->storage_socket[0], LOCK_EX); |
362d90b7 ZJS |
387 | if (r < 0) |
388 | return r; | |
29206d46 | 389 | |
1fe15cb7 | 390 | CLEANUP_POSIX_UNLOCK(d->storage_socket[0]); |
b4cbfa5f | 391 | |
c2983a7f | 392 | r = dynamic_user_pop(d, &num, &uid_lock_fd); |
29206d46 LP |
393 | if (r < 0) { |
394 | int new_uid_lock_fd; | |
395 | uid_t new_uid; | |
396 | ||
397 | if (r != -EAGAIN) | |
362d90b7 | 398 | return r; |
29206d46 LP |
399 | |
400 | /* OK, nothing stored yet, let's try to find something useful. While we are working on this release the | |
401 | * lock however, so that nobody else blocks on our NSS lookups. */ | |
1fe15cb7 | 402 | r = posix_lock(d->storage_socket[0], LOCK_UN); |
b4cbfa5f DDM |
403 | if (r < 0) |
404 | return r; | |
29206d46 LP |
405 | |
406 | /* Let's see if a proper, static user or group by this name exists. Try to take the lock on | |
407 | * /etc/passwd, if that fails with EROFS then /etc is read-only. In that case it's fine if we don't | |
408 | * take the lock, given that users can't be added there anyway in this case. */ | |
409 | etc_passwd_lock_fd = take_etc_passwd_lock(NULL); | |
410 | if (etc_passwd_lock_fd < 0 && etc_passwd_lock_fd != -EROFS) | |
411 | return etc_passwd_lock_fd; | |
412 | ||
413 | /* First, let's parse this as numeric UID */ | |
c2983a7f | 414 | r = parse_uid(d->name, &num); |
29206d46 LP |
415 | if (r < 0) { |
416 | struct passwd *p; | |
417 | struct group *g; | |
418 | ||
9ec655cb YW |
419 | if (is_user) { |
420 | /* OK, this is not a numeric UID. Let's see if there's a user by this name */ | |
421 | p = getpwnam(d->name); | |
c2983a7f ZJS |
422 | if (p) { |
423 | num = p->pw_uid; | |
424 | gid = p->pw_gid; | |
425 | } else { | |
9ec655cb YW |
426 | /* if the user does not exist but the group with the same name exists, refuse operation */ |
427 | g = getgrnam(d->name); | |
428 | if (g) | |
429 | return -EILSEQ; | |
430 | } | |
431 | } else { | |
432 | /* Let's see if there's a group by this name */ | |
433 | g = getgrnam(d->name); | |
434 | if (g) | |
c2983a7f | 435 | num = (uid_t) g->gr_gid; |
9ec655cb YW |
436 | else { |
437 | /* if the group does not exist but the user with the same name exists, refuse operation */ | |
438 | p = getpwnam(d->name); | |
439 | if (p) | |
440 | return -EILSEQ; | |
441 | } | |
29206d46 LP |
442 | } |
443 | } | |
444 | ||
c2983a7f | 445 | if (num == UID_INVALID) { |
29206d46 LP |
446 | /* No static UID assigned yet, excellent. Let's pick a new dynamic one, and lock it. */ |
447 | ||
c2983a7f | 448 | uid_lock_fd = pick_uid(suggested_dirs, d->name, &num); |
29206d46 LP |
449 | if (uid_lock_fd < 0) |
450 | return uid_lock_fd; | |
451 | } | |
452 | ||
453 | /* So, we found a working UID/lock combination. Let's see if we actually still need it. */ | |
1fe15cb7 | 454 | r = posix_lock(d->storage_socket[0], LOCK_EX); |
362d90b7 | 455 | if (r < 0) { |
c2983a7f | 456 | unlink_uid_lock(uid_lock_fd, num, d->name); |
362d90b7 | 457 | return r; |
29206d46 LP |
458 | } |
459 | ||
460 | r = dynamic_user_pop(d, &new_uid, &new_uid_lock_fd); | |
461 | if (r < 0) { | |
462 | if (r != -EAGAIN) { | |
463 | /* OK, something bad happened, let's get rid of the bits we acquired. */ | |
c2983a7f | 464 | unlink_uid_lock(uid_lock_fd, num, d->name); |
362d90b7 | 465 | return r; |
29206d46 LP |
466 | } |
467 | ||
468 | /* Great! Nothing is stored here, still. Store our newly acquired data. */ | |
460ec549 | 469 | flush_cache = true; |
29206d46 LP |
470 | } else { |
471 | /* Hmm, so as it appears there's now something stored in the storage socket. Throw away what we | |
472 | * acquired, and use what's stored now. */ | |
473 | ||
c2983a7f | 474 | unlink_uid_lock(uid_lock_fd, num, d->name); |
29206d46 LP |
475 | safe_close(uid_lock_fd); |
476 | ||
c2983a7f | 477 | num = new_uid; |
29206d46 LP |
478 | uid_lock_fd = new_uid_lock_fd; |
479 | } | |
25a1df7c YW |
480 | } else if (is_user && !uid_is_dynamic(num)) { |
481 | struct passwd *p; | |
482 | ||
483 | /* Statically allocated user may have different uid and gid. So, let's obtain the gid. */ | |
484 | errno = 0; | |
485 | p = getpwuid(num); | |
486 | if (!p) | |
66855de7 | 487 | return errno_or_else(ESRCH); |
25a1df7c YW |
488 | |
489 | gid = p->pw_gid; | |
29206d46 LP |
490 | } |
491 | ||
492 | /* If the UID/GID was already allocated dynamically, push the data we popped out back in. If it was already | |
493 | * allocated statically, push the UID back too, but do not push the lock fd in. If we allocated the UID | |
494 | * dynamically right here, push that in along with the lock fd for it. */ | |
c2983a7f | 495 | r = dynamic_user_push(d, num, uid_lock_fd); |
29206d46 | 496 | if (r < 0) |
362d90b7 | 497 | return r; |
29206d46 | 498 | |
460ec549 LP |
499 | if (flush_cache) { |
500 | /* If we allocated a new dynamic UID, refresh nscd, so that it forgets about potentially cached | |
501 | * negative entries. But let's do so after we release the /etc/passwd lock, so that there's no | |
502 | * potential for nscd wanting to lock that for completing the invalidation. */ | |
503 | etc_passwd_lock_fd = safe_close(etc_passwd_lock_fd); | |
504 | (void) nscd_flush_cache(STRV_MAKE("passwd", "group")); | |
505 | } | |
506 | ||
c2983a7f ZJS |
507 | if (is_user) { |
508 | *ret_uid = num; | |
509 | *ret_gid = gid != GID_INVALID ? gid : num; | |
510 | } else | |
511 | *ret_gid = num; | |
512 | ||
362d90b7 | 513 | return 0; |
29206d46 LP |
514 | } |
515 | ||
f9bfa696 | 516 | int dynamic_user_current(DynamicUser *d, uid_t *ret) { |
254d1313 | 517 | _cleanup_close_ int lock_fd = -EBADF; |
29206d46 LP |
518 | uid_t uid; |
519 | int r; | |
520 | ||
521 | assert(d); | |
29206d46 | 522 | |
8b98cfb7 ZJS |
523 | /* Get the currently assigned UID for the user, if there's any. This simply pops the data from the |
524 | * storage socket, and pushes it back in right-away. */ | |
29206d46 | 525 | |
1fe15cb7 | 526 | r = posix_lock(d->storage_socket[0], LOCK_EX); |
362d90b7 ZJS |
527 | if (r < 0) |
528 | return r; | |
29206d46 | 529 | |
1fe15cb7 | 530 | CLEANUP_POSIX_UNLOCK(d->storage_socket[0]); |
b4cbfa5f | 531 | |
29206d46 LP |
532 | r = dynamic_user_pop(d, &uid, &lock_fd); |
533 | if (r < 0) | |
362d90b7 | 534 | return r; |
29206d46 LP |
535 | |
536 | r = dynamic_user_push(d, uid, lock_fd); | |
537 | if (r < 0) | |
362d90b7 | 538 | return r; |
29206d46 | 539 | |
4bad7eed LP |
540 | if (ret) |
541 | *ret = uid; | |
542 | ||
362d90b7 | 543 | return 0; |
29206d46 LP |
544 | } |
545 | ||
9da440b1 | 546 | static DynamicUser* dynamic_user_unref(DynamicUser *d) { |
29206d46 LP |
547 | if (!d) |
548 | return NULL; | |
549 | ||
8b98cfb7 ZJS |
550 | /* Note that this doesn't actually release any resources itself. If a dynamic user should be fully |
551 | * destroyed and its UID released, use dynamic_user_destroy() instead. NB: the dynamic user table may | |
552 | * contain entries with no references, which is commonly the case right before a daemon reload. */ | |
29206d46 LP |
553 | |
554 | assert(d->n_ref > 0); | |
555 | d->n_ref--; | |
556 | ||
557 | return NULL; | |
558 | } | |
559 | ||
560 | static int dynamic_user_close(DynamicUser *d) { | |
254d1313 | 561 | _cleanup_close_ int lock_fd = -EBADF; |
29206d46 LP |
562 | uid_t uid; |
563 | int r; | |
564 | ||
8b98cfb7 ZJS |
565 | /* Release the user ID, by releasing the lock on it, and emptying the storage socket. After this the |
566 | * user is unrealized again, much like it was after it the DynamicUser object was first allocated. */ | |
29206d46 | 567 | |
1fe15cb7 | 568 | r = posix_lock(d->storage_socket[0], LOCK_EX); |
362d90b7 ZJS |
569 | if (r < 0) |
570 | return r; | |
29206d46 | 571 | |
1fe15cb7 | 572 | CLEANUP_POSIX_UNLOCK(d->storage_socket[0]); |
b4cbfa5f | 573 | |
29206d46 | 574 | r = dynamic_user_pop(d, &uid, &lock_fd); |
362d90b7 | 575 | if (r == -EAGAIN) |
29206d46 | 576 | /* User wasn't realized yet, nothing to do. */ |
362d90b7 | 577 | return 0; |
29206d46 | 578 | if (r < 0) |
362d90b7 | 579 | return r; |
29206d46 LP |
580 | |
581 | /* This dynamic user was realized and dynamically allocated. In this case, let's remove the lock file. */ | |
fd63e712 | 582 | unlink_uid_lock(lock_fd, uid, d->name); |
460ec549 LP |
583 | |
584 | (void) nscd_flush_cache(STRV_MAKE("passwd", "group")); | |
362d90b7 | 585 | return 1; |
29206d46 LP |
586 | } |
587 | ||
9da440b1 | 588 | static DynamicUser* dynamic_user_destroy(DynamicUser *d) { |
29206d46 LP |
589 | if (!d) |
590 | return NULL; | |
591 | ||
592 | /* Drop a reference to a DynamicUser object, and destroy the user completely if this was the last | |
593 | * reference. This is called whenever a service is shut down and wants its dynamic UID gone. Note that | |
594 | * dynamic_user_unref() is what is called whenever a service is simply freed, for example during a reload | |
595 | * cycle, where the dynamic users should not be destroyed, but our datastructures should. */ | |
596 | ||
597 | dynamic_user_unref(d); | |
598 | ||
599 | if (d->n_ref > 0) | |
600 | return NULL; | |
601 | ||
602 | (void) dynamic_user_close(d); | |
603 | return dynamic_user_free(d); | |
604 | } | |
605 | ||
606 | int dynamic_user_serialize(Manager *m, FILE *f, FDSet *fds) { | |
607 | DynamicUser *d; | |
29206d46 LP |
608 | |
609 | assert(m); | |
610 | assert(f); | |
611 | assert(fds); | |
612 | ||
613 | /* Dump the dynamic user database into the manager serialization, to deal with daemon reloads. */ | |
614 | ||
90e74a66 | 615 | HASHMAP_FOREACH(d, m->dynamic_users) { |
29206d46 LP |
616 | int copy0, copy1; |
617 | ||
618 | copy0 = fdset_put_dup(fds, d->storage_socket[0]); | |
619 | if (copy0 < 0) | |
d68c645b | 620 | return log_error_errno(copy0, "Failed to add dynamic user storage fd to serialization: %m"); |
29206d46 LP |
621 | |
622 | copy1 = fdset_put_dup(fds, d->storage_socket[1]); | |
623 | if (copy1 < 0) | |
d68c645b | 624 | return log_error_errno(copy1, "Failed to add dynamic user storage fd to serialization: %m"); |
29206d46 | 625 | |
d68c645b | 626 | (void) serialize_item_format(f, "dynamic-user", "%s %i %i", d->name, copy0, copy1); |
29206d46 LP |
627 | } |
628 | ||
629 | return 0; | |
630 | } | |
631 | ||
632 | void dynamic_user_deserialize_one(Manager *m, const char *value, FDSet *fds) { | |
633 | _cleanup_free_ char *name = NULL, *s0 = NULL, *s1 = NULL; | |
634 | int r, fd0, fd1; | |
635 | ||
636 | assert(m); | |
637 | assert(value); | |
638 | assert(fds); | |
639 | ||
640 | /* Parse the serialization again, after a daemon reload */ | |
641 | ||
642 | r = extract_many_words(&value, NULL, 0, &name, &s0, &s1, NULL); | |
643 | if (r != 3 || !isempty(value)) { | |
644 | log_debug("Unable to parse dynamic user line."); | |
645 | return; | |
646 | } | |
647 | ||
e652663a | 648 | if ((fd0 = parse_fd(s0)) < 0 || !fdset_contains(fds, fd0)) { |
29206d46 LP |
649 | log_debug("Unable to process dynamic user fd specification."); |
650 | return; | |
651 | } | |
652 | ||
e652663a | 653 | if ((fd1 = parse_fd(s1)) < 0 || !fdset_contains(fds, fd1)) { |
29206d46 LP |
654 | log_debug("Unable to process dynamic user fd specification."); |
655 | return; | |
656 | } | |
657 | ||
658 | r = dynamic_user_add(m, name, (int[]) { fd0, fd1 }, NULL); | |
659 | if (r < 0) { | |
660 | log_debug_errno(r, "Failed to add dynamic user: %m"); | |
661 | return; | |
662 | } | |
663 | ||
664 | (void) fdset_remove(fds, fd0); | |
665 | (void) fdset_remove(fds, fd1); | |
666 | } | |
667 | ||
668 | void dynamic_user_vacuum(Manager *m, bool close_user) { | |
669 | DynamicUser *d; | |
29206d46 LP |
670 | |
671 | assert(m); | |
672 | ||
673 | /* Empty the dynamic user database, optionally cleaning up orphaned dynamic users, i.e. destroy and free users | |
674 | * to which no reference exist. This is called after a daemon reload finished, in order to destroy users which | |
675 | * might not be referenced anymore. */ | |
676 | ||
90e74a66 | 677 | HASHMAP_FOREACH(d, m->dynamic_users) { |
29206d46 LP |
678 | if (d->n_ref > 0) |
679 | continue; | |
680 | ||
681 | if (close_user) { | |
682 | log_debug("Removing orphaned dynamic user %s", d->name); | |
683 | (void) dynamic_user_close(d); | |
684 | } | |
685 | ||
686 | dynamic_user_free(d); | |
687 | } | |
688 | } | |
689 | ||
690 | int dynamic_user_lookup_uid(Manager *m, uid_t uid, char **ret) { | |
fbd0b64f | 691 | char lock_path[STRLEN("/run/systemd/dynamic-uid/") + DECIMAL_STR_MAX(uid_t) + 1]; |
29206d46 LP |
692 | _cleanup_free_ char *user = NULL; |
693 | uid_t check_uid; | |
694 | int r; | |
695 | ||
696 | assert(m); | |
697 | assert(ret); | |
698 | ||
61755fda ZJS |
699 | /* A friendly way to translate a dynamic user's UID into a name. */ |
700 | if (!uid_is_dynamic(uid)) | |
29206d46 LP |
701 | return -ESRCH; |
702 | ||
703 | xsprintf(lock_path, "/run/systemd/dynamic-uid/" UID_FMT, uid); | |
704 | r = read_one_line_file(lock_path, &user); | |
a2176045 | 705 | if (IN_SET(r, -ENOENT, 0)) |
29206d46 LP |
706 | return -ESRCH; |
707 | if (r < 0) | |
708 | return r; | |
709 | ||
710 | /* The lock file might be stale, hence let's verify the data before we return it */ | |
711 | r = dynamic_user_lookup_name(m, user, &check_uid); | |
712 | if (r < 0) | |
713 | return r; | |
714 | if (check_uid != uid) /* lock file doesn't match our own idea */ | |
715 | return -ESRCH; | |
716 | ||
ae2a15bc | 717 | *ret = TAKE_PTR(user); |
29206d46 LP |
718 | |
719 | return 0; | |
720 | } | |
721 | ||
722 | int dynamic_user_lookup_name(Manager *m, const char *name, uid_t *ret) { | |
723 | DynamicUser *d; | |
724 | int r; | |
725 | ||
726 | assert(m); | |
727 | assert(name); | |
29206d46 LP |
728 | |
729 | /* A friendly call for translating a dynamic user's name into its UID */ | |
730 | ||
731 | d = hashmap_get(m->dynamic_users, name); | |
732 | if (!d) | |
733 | return -ESRCH; | |
734 | ||
735 | r = dynamic_user_current(d, ret); | |
736 | if (r == -EAGAIN) /* not realized yet? */ | |
737 | return -ESRCH; | |
738 | ||
739 | return r; | |
740 | } | |
741 | ||
15220772 DDM |
742 | int dynamic_creds_make(Manager *m, const char *user, const char *group, DynamicCreds **ret) { |
743 | _cleanup_(dynamic_creds_unrefp) DynamicCreds *creds = NULL; | |
29206d46 LP |
744 | bool acquired = false; |
745 | int r; | |
746 | ||
29206d46 | 747 | assert(m); |
15220772 DDM |
748 | assert(ret); |
749 | ||
750 | if (!user && !group) { | |
751 | *ret = NULL; | |
752 | return 0; | |
753 | } | |
754 | ||
755 | creds = new0(DynamicCreds, 1); | |
756 | if (!creds) | |
757 | return -ENOMEM; | |
29206d46 LP |
758 | |
759 | /* A DynamicUser object encapsulates an allocation of both a UID and a GID for a specific name. However, some | |
760 | * services use different user and groups. For cases like that there's DynamicCreds containing a pair of user | |
761 | * and group. This call allocates a pair. */ | |
762 | ||
15220772 | 763 | if (user) { |
29206d46 LP |
764 | r = dynamic_user_acquire(m, user, &creds->user); |
765 | if (r < 0) | |
766 | return r; | |
767 | ||
768 | acquired = true; | |
769 | } | |
770 | ||
15220772 DDM |
771 | if (creds->user && (!group || streq_ptr(user, group))) |
772 | creds->group = dynamic_user_ref(creds->user); | |
773 | else if (group) { | |
774 | r = dynamic_user_acquire(m, group, &creds->group); | |
775 | if (r < 0) { | |
776 | if (acquired) | |
777 | creds->user = dynamic_user_unref(creds->user); | |
778 | return r; | |
29206d46 LP |
779 | } |
780 | } | |
781 | ||
15220772 DDM |
782 | *ret = TAKE_PTR(creds); |
783 | ||
29206d46 LP |
784 | return 0; |
785 | } | |
786 | ||
da50b85a | 787 | int dynamic_creds_realize(DynamicCreds *creds, char **suggested_paths, uid_t *uid, gid_t *gid) { |
29206d46 LP |
788 | uid_t u = UID_INVALID; |
789 | gid_t g = GID_INVALID; | |
790 | int r; | |
791 | ||
792 | assert(creds); | |
793 | assert(uid); | |
794 | assert(gid); | |
795 | ||
796 | /* Realize both the referenced user and group */ | |
797 | ||
798 | if (creds->user) { | |
c2983a7f | 799 | r = dynamic_user_realize(creds->user, suggested_paths, &u, &g, true); |
29206d46 LP |
800 | if (r < 0) |
801 | return r; | |
802 | } | |
803 | ||
804 | if (creds->group && creds->group != creds->user) { | |
c2983a7f | 805 | r = dynamic_user_realize(creds->group, suggested_paths, NULL, &g, false); |
29206d46 LP |
806 | if (r < 0) |
807 | return r; | |
c2983a7f | 808 | } |
29206d46 LP |
809 | |
810 | *uid = u; | |
811 | *gid = g; | |
29206d46 LP |
812 | return 0; |
813 | } | |
814 | ||
15220772 DDM |
815 | DynamicCreds* dynamic_creds_unref(DynamicCreds *creds) { |
816 | if (!creds) | |
817 | return NULL; | |
29206d46 LP |
818 | |
819 | creds->user = dynamic_user_unref(creds->user); | |
820 | creds->group = dynamic_user_unref(creds->group); | |
15220772 DDM |
821 | |
822 | return mfree(creds); | |
29206d46 LP |
823 | } |
824 | ||
15220772 DDM |
825 | DynamicCreds* dynamic_creds_destroy(DynamicCreds *creds) { |
826 | if (!creds) | |
827 | return NULL; | |
29206d46 LP |
828 | |
829 | creds->user = dynamic_user_destroy(creds->user); | |
830 | creds->group = dynamic_user_destroy(creds->group); | |
15220772 DDM |
831 | |
832 | return mfree(creds); | |
29206d46 | 833 | } |