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Commit | Line | Data |
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db9ecf05 | 1 | /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
7336138e LP |
2 | |
3 | #include <fcntl.h> | |
3603efde | 4 | #include <sys/statvfs.h> |
88cd066e | 5 | #include <sys/vfs.h> |
7336138e LP |
6 | #include <unistd.h> |
7 | ||
8 | #include "acl-util.h" | |
9 | #include "dirent-util.h" | |
10 | #include "fd-util.h" | |
9f81a592 | 11 | #include "fileio.h" |
3603efde | 12 | #include "fs-util.h" |
f5947a5e | 13 | #include "missing_magic.h" |
3603efde | 14 | #include "nspawn-def.h" |
7336138e | 15 | #include "nspawn-patch-uid.h" |
88cd066e | 16 | #include "stat-util.h" |
7336138e LP |
17 | #include "stdio-util.h" |
18 | #include "string-util.h" | |
19 | #include "strv.h" | |
20 | #include "user-util.h" | |
21 | ||
349cc4a5 | 22 | #if HAVE_ACL |
7336138e LP |
23 | |
24 | static int get_acl(int fd, const char *name, acl_type_t type, acl_t *ret) { | |
7336138e LP |
25 | acl_t acl; |
26 | ||
27 | assert(fd >= 0); | |
28 | assert(ret); | |
29 | ||
30 | if (name) { | |
254d1313 | 31 | _cleanup_close_ int child_fd = -EBADF; |
7336138e LP |
32 | |
33 | child_fd = openat(fd, name, O_PATH|O_CLOEXEC|O_NOFOLLOW); | |
34 | if (child_fd < 0) | |
35 | return -errno; | |
36 | ||
ddb6eeaf | 37 | acl = acl_get_file(FORMAT_PROC_FD_PATH(child_fd), type); |
7336138e LP |
38 | } else if (type == ACL_TYPE_ACCESS) |
39 | acl = acl_get_fd(fd); | |
ddb6eeaf LP |
40 | else |
41 | acl = acl_get_file(FORMAT_PROC_FD_PATH(fd), type); | |
7336138e LP |
42 | if (!acl) |
43 | return -errno; | |
44 | ||
45 | *ret = acl; | |
46 | return 0; | |
47 | } | |
48 | ||
49 | static int set_acl(int fd, const char *name, acl_type_t type, acl_t acl) { | |
7336138e LP |
50 | int r; |
51 | ||
52 | assert(fd >= 0); | |
53 | assert(acl); | |
54 | ||
55 | if (name) { | |
254d1313 | 56 | _cleanup_close_ int child_fd = -EBADF; |
7336138e LP |
57 | |
58 | child_fd = openat(fd, name, O_PATH|O_CLOEXEC|O_NOFOLLOW); | |
59 | if (child_fd < 0) | |
60 | return -errno; | |
61 | ||
ddb6eeaf | 62 | r = acl_set_file(FORMAT_PROC_FD_PATH(child_fd), type, acl); |
7336138e LP |
63 | } else if (type == ACL_TYPE_ACCESS) |
64 | r = acl_set_fd(fd, acl); | |
ddb6eeaf LP |
65 | else |
66 | r = acl_set_file(FORMAT_PROC_FD_PATH(fd), type, acl); | |
7336138e LP |
67 | if (r < 0) |
68 | return -errno; | |
69 | ||
70 | return 0; | |
71 | } | |
72 | ||
73 | static int shift_acl(acl_t acl, uid_t shift, acl_t *ret) { | |
74 | _cleanup_(acl_freep) acl_t copy = NULL; | |
75 | acl_entry_t i; | |
76 | int r; | |
77 | ||
78 | assert(acl); | |
79 | assert(ret); | |
80 | ||
81 | r = acl_get_entry(acl, ACL_FIRST_ENTRY, &i); | |
82 | if (r < 0) | |
83 | return -errno; | |
84 | while (r > 0) { | |
85 | uid_t *old_uid, new_uid; | |
86 | bool modify = false; | |
87 | acl_tag_t tag; | |
88 | ||
89 | if (acl_get_tag_type(i, &tag) < 0) | |
90 | return -errno; | |
91 | ||
92 | if (IN_SET(tag, ACL_USER, ACL_GROUP)) { | |
93 | ||
5238e957 | 94 | /* We don't distinguish here between uid_t and gid_t, let's make sure the compiler checks that |
7336138e LP |
95 | * this is actually OK */ |
96 | assert_cc(sizeof(uid_t) == sizeof(gid_t)); | |
97 | ||
98 | old_uid = acl_get_qualifier(i); | |
99 | if (!old_uid) | |
100 | return -errno; | |
101 | ||
102 | new_uid = shift | (*old_uid & UINT32_C(0xFFFF)); | |
103 | if (!uid_is_valid(new_uid)) | |
104 | return -EINVAL; | |
105 | ||
106 | modify = new_uid != *old_uid; | |
107 | if (modify && !copy) { | |
108 | int n; | |
109 | ||
110 | /* There's no copy of the ACL yet? if so, let's create one, and start the loop from the | |
111 | * beginning, so that we copy all entries, starting from the first, this time. */ | |
112 | ||
113 | n = acl_entries(acl); | |
114 | if (n < 0) | |
115 | return -errno; | |
116 | ||
117 | copy = acl_init(n); | |
118 | if (!copy) | |
119 | return -errno; | |
120 | ||
121 | /* Seek back to the beginning */ | |
122 | r = acl_get_entry(acl, ACL_FIRST_ENTRY, &i); | |
123 | if (r < 0) | |
124 | return -errno; | |
125 | continue; | |
126 | } | |
127 | } | |
128 | ||
129 | if (copy) { | |
130 | acl_entry_t new_entry; | |
131 | ||
132 | if (acl_create_entry(©, &new_entry) < 0) | |
133 | return -errno; | |
134 | ||
135 | if (acl_copy_entry(new_entry, i) < 0) | |
136 | return -errno; | |
137 | ||
138 | if (modify) | |
139 | if (acl_set_qualifier(new_entry, &new_uid) < 0) | |
140 | return -errno; | |
141 | } | |
142 | ||
143 | r = acl_get_entry(acl, ACL_NEXT_ENTRY, &i); | |
144 | if (r < 0) | |
145 | return -errno; | |
146 | } | |
147 | ||
1cc6c93a | 148 | *ret = TAKE_PTR(copy); |
7336138e LP |
149 | |
150 | return !!*ret; | |
151 | } | |
152 | ||
153 | static int patch_acls(int fd, const char *name, const struct stat *st, uid_t shift) { | |
154 | _cleanup_(acl_freep) acl_t acl = NULL, shifted = NULL; | |
155 | bool changed = false; | |
156 | int r; | |
157 | ||
158 | assert(fd >= 0); | |
159 | assert(st); | |
160 | ||
161 | /* ACLs are not supported on symlinks, there's no point in trying */ | |
162 | if (S_ISLNK(st->st_mode)) | |
163 | return 0; | |
164 | ||
165 | r = get_acl(fd, name, ACL_TYPE_ACCESS, &acl); | |
166 | if (r == -EOPNOTSUPP) | |
167 | return 0; | |
168 | if (r < 0) | |
169 | return r; | |
170 | ||
171 | r = shift_acl(acl, shift, &shifted); | |
172 | if (r < 0) | |
173 | return r; | |
174 | if (r > 0) { | |
175 | r = set_acl(fd, name, ACL_TYPE_ACCESS, shifted); | |
176 | if (r < 0) | |
177 | return r; | |
178 | ||
179 | changed = true; | |
180 | } | |
181 | ||
182 | if (S_ISDIR(st->st_mode)) { | |
183 | acl_free(acl); | |
34680637 LP |
184 | |
185 | if (shifted) | |
186 | acl_free(shifted); | |
7336138e LP |
187 | |
188 | acl = shifted = NULL; | |
189 | ||
190 | r = get_acl(fd, name, ACL_TYPE_DEFAULT, &acl); | |
191 | if (r < 0) | |
192 | return r; | |
193 | ||
194 | r = shift_acl(acl, shift, &shifted); | |
195 | if (r < 0) | |
196 | return r; | |
197 | if (r > 0) { | |
198 | r = set_acl(fd, name, ACL_TYPE_DEFAULT, shifted); | |
199 | if (r < 0) | |
200 | return r; | |
201 | ||
202 | changed = true; | |
203 | } | |
204 | } | |
205 | ||
206 | return changed; | |
207 | } | |
208 | ||
209 | #else | |
210 | ||
211 | static int patch_acls(int fd, const char *name, const struct stat *st, uid_t shift) { | |
212 | return 0; | |
213 | } | |
214 | ||
215 | #endif | |
216 | ||
217 | static int patch_fd(int fd, const char *name, const struct stat *st, uid_t shift) { | |
218 | uid_t new_uid; | |
219 | gid_t new_gid; | |
220 | bool changed = false; | |
221 | int r; | |
222 | ||
223 | assert(fd >= 0); | |
224 | assert(st); | |
225 | ||
226 | new_uid = shift | (st->st_uid & UINT32_C(0xFFFF)); | |
227 | new_gid = (gid_t) shift | (st->st_gid & UINT32_C(0xFFFF)); | |
228 | ||
229 | if (!uid_is_valid(new_uid) || !gid_is_valid(new_gid)) | |
230 | return -EINVAL; | |
231 | ||
232 | if (st->st_uid != new_uid || st->st_gid != new_gid) { | |
233 | if (name) | |
234 | r = fchownat(fd, name, new_uid, new_gid, AT_SYMLINK_NOFOLLOW); | |
235 | else | |
236 | r = fchown(fd, new_uid, new_gid); | |
237 | if (r < 0) | |
238 | return -errno; | |
239 | ||
240 | /* The Linux kernel alters the mode in some cases of chown(). Let's undo this. */ | |
0c6aeb46 LP |
241 | if (name) { |
242 | if (!S_ISLNK(st->st_mode)) | |
677e6445 | 243 | r = fchmodat(fd, name, st->st_mode, 0); |
0cdffada | 244 | else /* Changing the mode of a symlink is not supported by Linux kernel. Don't bother. */ |
677e6445 | 245 | r = 0; |
0c6aeb46 | 246 | } else |
677e6445 | 247 | r = fchmod(fd, st->st_mode); |
7336138e | 248 | if (r < 0) |
677e6445 | 249 | return -errno; |
7336138e LP |
250 | |
251 | changed = true; | |
252 | } | |
253 | ||
254 | r = patch_acls(fd, name, st, shift); | |
255 | if (r < 0) | |
256 | return r; | |
257 | ||
258 | return r > 0 || changed; | |
259 | } | |
260 | ||
231bfb1b DH |
261 | /* |
262 | * Check if the filesystem is fully compatible with user namespaces or | |
263 | * UID/GID patching. Some filesystems in this list can be fully mounted inside | |
264 | * user namespaces, however their inodes may relate to host resources or only | |
265 | * valid in the global user namespace, therefore no patching should be applied. | |
266 | */ | |
3603efde LP |
267 | static int is_fs_fully_userns_compatible(const struct statfs *sfs) { |
268 | ||
269 | assert(sfs); | |
270 | ||
271 | return F_TYPE_EQUAL(sfs->f_type, BINFMTFS_MAGIC) || | |
272 | F_TYPE_EQUAL(sfs->f_type, CGROUP_SUPER_MAGIC) || | |
273 | F_TYPE_EQUAL(sfs->f_type, CGROUP2_SUPER_MAGIC) || | |
274 | F_TYPE_EQUAL(sfs->f_type, DEBUGFS_MAGIC) || | |
275 | F_TYPE_EQUAL(sfs->f_type, DEVPTS_SUPER_MAGIC) || | |
276 | F_TYPE_EQUAL(sfs->f_type, EFIVARFS_MAGIC) || | |
277 | F_TYPE_EQUAL(sfs->f_type, HUGETLBFS_MAGIC) || | |
278 | F_TYPE_EQUAL(sfs->f_type, MQUEUE_MAGIC) || | |
279 | F_TYPE_EQUAL(sfs->f_type, PROC_SUPER_MAGIC) || | |
280 | F_TYPE_EQUAL(sfs->f_type, PSTOREFS_MAGIC) || | |
281 | F_TYPE_EQUAL(sfs->f_type, SELINUX_MAGIC) || | |
282 | F_TYPE_EQUAL(sfs->f_type, SMACK_MAGIC) || | |
283 | F_TYPE_EQUAL(sfs->f_type, SECURITYFS_MAGIC) || | |
284 | F_TYPE_EQUAL(sfs->f_type, BPF_FS_MAGIC) || | |
285 | F_TYPE_EQUAL(sfs->f_type, TRACEFS_MAGIC) || | |
286 | F_TYPE_EQUAL(sfs->f_type, SYSFS_MAGIC); | |
88cd066e LP |
287 | } |
288 | ||
4aeb20f5 | 289 | static int recurse_fd(int fd, bool donate_fd, const struct stat *st, uid_t shift, bool is_toplevel) { |
3603efde | 290 | _cleanup_closedir_ DIR *d = NULL; |
7336138e | 291 | bool changed = false; |
3603efde | 292 | struct statfs sfs; |
7336138e LP |
293 | int r; |
294 | ||
295 | assert(fd >= 0); | |
296 | ||
3603efde LP |
297 | if (fstatfs(fd, &sfs) < 0) |
298 | return -errno; | |
299 | ||
300 | /* We generally want to permit crossing of mount boundaries when patching the UIDs/GIDs. However, we probably | |
301 | * shouldn't do this for /proc and /sys if that is already mounted into place. Hence, let's stop the recursion | |
302 | * when we hit procfs, sysfs or some other special file systems. */ | |
303 | ||
304 | r = is_fs_fully_userns_compatible(&sfs); | |
88cd066e LP |
305 | if (r < 0) |
306 | goto finish; | |
307 | if (r > 0) { | |
308 | r = 0; /* don't recurse */ | |
309 | goto finish; | |
310 | } | |
311 | ||
3603efde LP |
312 | /* Also, if we hit a read-only file system, then don't bother, skip the whole subtree */ |
313 | if ((sfs.f_flags & ST_RDONLY) || | |
314 | access_fd(fd, W_OK) == -EROFS) | |
315 | goto read_only; | |
7336138e LP |
316 | |
317 | if (S_ISDIR(st->st_mode)) { | |
7336138e LP |
318 | if (!donate_fd) { |
319 | int copy; | |
320 | ||
321 | copy = fcntl(fd, F_DUPFD_CLOEXEC, 3); | |
88cd066e LP |
322 | if (copy < 0) { |
323 | r = -errno; | |
324 | goto finish; | |
325 | } | |
7336138e LP |
326 | |
327 | fd = copy; | |
328 | donate_fd = true; | |
329 | } | |
330 | ||
9f81a592 | 331 | d = take_fdopendir(&fd); |
7336138e LP |
332 | if (!d) { |
333 | r = -errno; | |
334 | goto finish; | |
335 | } | |
7336138e LP |
336 | |
337 | FOREACH_DIRENT_ALL(de, d, r = -errno; goto finish) { | |
338 | struct stat fst; | |
339 | ||
49bfc877 | 340 | if (dot_or_dot_dot(de->d_name)) |
7336138e LP |
341 | continue; |
342 | ||
343 | if (fstatat(dirfd(d), de->d_name, &fst, AT_SYMLINK_NOFOLLOW) < 0) { | |
344 | r = -errno; | |
345 | goto finish; | |
346 | } | |
347 | ||
348 | if (S_ISDIR(fst.st_mode)) { | |
349 | int subdir_fd; | |
350 | ||
351 | subdir_fd = openat(dirfd(d), de->d_name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME); | |
352 | if (subdir_fd < 0) { | |
353 | r = -errno; | |
354 | goto finish; | |
355 | ||
356 | } | |
357 | ||
4aeb20f5 | 358 | r = recurse_fd(subdir_fd, true, &fst, shift, false); |
7336138e LP |
359 | if (r < 0) |
360 | goto finish; | |
361 | if (r > 0) | |
362 | changed = true; | |
363 | ||
364 | } else { | |
365 | r = patch_fd(dirfd(d), de->d_name, &fst, shift); | |
366 | if (r < 0) | |
367 | goto finish; | |
368 | if (r > 0) | |
369 | changed = true; | |
370 | } | |
371 | } | |
372 | } | |
373 | ||
3603efde LP |
374 | /* After we descended, also patch the directory itself. It's key to do this in this order so that the top-level |
375 | * directory is patched as very last object in the tree, so that we can use it as quick indicator whether the | |
376 | * tree is properly chown()ed already. */ | |
377 | r = patch_fd(d ? dirfd(d) : fd, NULL, st, shift); | |
378 | if (r == -EROFS) | |
379 | goto read_only; | |
380 | if (r > 0) | |
381 | changed = true; | |
382 | ||
7336138e | 383 | r = changed; |
3603efde LP |
384 | goto finish; |
385 | ||
386 | read_only: | |
387 | if (!is_toplevel) { | |
388 | _cleanup_free_ char *name = NULL; | |
389 | ||
390 | /* When we hit a ready-only subtree we simply skip it, but log about it. */ | |
391 | (void) fd_get_path(fd, &name); | |
ebcf6976 | 392 | log_debug("Skipping read-only file or directory %s.", strna(name)); |
3603efde LP |
393 | r = changed; |
394 | } | |
7336138e LP |
395 | |
396 | finish: | |
397 | if (donate_fd) | |
398 | safe_close(fd); | |
399 | ||
400 | return r; | |
401 | } | |
402 | ||
403 | static int fd_patch_uid_internal(int fd, bool donate_fd, uid_t shift, uid_t range) { | |
404 | struct stat st; | |
405 | int r; | |
406 | ||
407 | assert(fd >= 0); | |
408 | ||
409 | /* Recursively adjusts the UID/GIDs of all files of a directory tree. This is used to automatically fix up an | |
410 | * OS tree to the used user namespace UID range. Note that this automatic adjustment only works for UID ranges | |
da890466 | 411 | * following the concept that the upper 16-bit of a UID identify the container, and the lower 16-bit are the actual |
7336138e LP |
412 | * UID within the container. */ |
413 | ||
414 | if ((shift & 0xFFFF) != 0) { | |
415 | /* We only support containers where the shift starts at a 2^16 boundary */ | |
416 | r = -EOPNOTSUPP; | |
417 | goto finish; | |
418 | } | |
419 | ||
3603efde LP |
420 | if (shift == UID_BUSY_BASE) { |
421 | r = -EINVAL; | |
422 | goto finish; | |
423 | } | |
424 | ||
7336138e | 425 | if (range != 0x10000) { |
da890466 | 426 | /* We only support containers with 16-bit UID ranges for the patching logic */ |
7336138e LP |
427 | r = -EOPNOTSUPP; |
428 | goto finish; | |
429 | } | |
430 | ||
431 | if (fstat(fd, &st) < 0) { | |
432 | r = -errno; | |
433 | goto finish; | |
434 | } | |
435 | ||
436 | if ((uint32_t) st.st_uid >> 16 != (uint32_t) st.st_gid >> 16) { | |
437 | /* We only support containers where the uid/gid container ID match */ | |
438 | r = -EBADE; | |
439 | goto finish; | |
440 | } | |
441 | ||
442 | /* Try to detect if the range is already right. Of course, this a pretty drastic optimization, as we assume | |
da890466 | 443 | * that if the top-level dir has the right upper 16-bit assigned, then everything below will have too... */ |
7336138e LP |
444 | if (((uint32_t) (st.st_uid ^ shift) >> 16) == 0) |
445 | return 0; | |
446 | ||
3603efde LP |
447 | /* Before we start recursively chowning, mark the top-level dir as "busy" by chowning it to the "busy" |
448 | * range. Should we be interrupted in the middle of our work, we'll see it owned by this user and will start | |
449 | * chown()ing it again, unconditionally, as the busy UID is not a valid UID we'd everpick for ourselves. */ | |
450 | ||
451 | if ((st.st_uid & UID_BUSY_MASK) != UID_BUSY_BASE) { | |
452 | if (fchown(fd, | |
453 | UID_BUSY_BASE | (st.st_uid & ~UID_BUSY_MASK), | |
454 | (gid_t) UID_BUSY_BASE | (st.st_gid & ~(gid_t) UID_BUSY_MASK)) < 0) { | |
455 | r = -errno; | |
456 | goto finish; | |
457 | } | |
458 | } | |
459 | ||
4aeb20f5 | 460 | return recurse_fd(fd, donate_fd, &st, shift, true); |
7336138e LP |
461 | |
462 | finish: | |
463 | if (donate_fd) | |
464 | safe_close(fd); | |
465 | ||
466 | return r; | |
467 | } | |
468 | ||
7336138e LP |
469 | int path_patch_uid(const char *path, uid_t shift, uid_t range) { |
470 | int fd; | |
471 | ||
472 | fd = open(path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME); | |
473 | if (fd < 0) | |
474 | return -errno; | |
475 | ||
476 | return fd_patch_uid_internal(fd, true, shift, range); | |
477 | } |