Commit | Line | Data |
---|---|---|
60b6c79c MD |
1 | /* |
2 | * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca> | |
3 | * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
4 | * | |
d14d33bf AM |
5 | * This program is free software; you can redistribute it and/or modify |
6 | * it under the terms of the GNU General Public License, version 2 only, | |
7 | * as published by the Free Software Foundation. | |
60b6c79c MD |
8 | * |
9 | * This program is distributed in the hope that it will be useful, but WITHOUT | |
10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
d14d33bf | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
60b6c79c MD |
12 | * more details. |
13 | * | |
d14d33bf AM |
14 | * You should have received a copy of the GNU General Public License along |
15 | * with this program; if not, write to the Free Software Foundation, Inc., | |
16 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | |
60b6c79c MD |
17 | */ |
18 | ||
19 | #define _GNU_SOURCE | |
6c1c0768 | 20 | #define _LGPL_SOURCE |
60b6c79c MD |
21 | #include <errno.h> |
22 | #include <limits.h> | |
23 | #include <stdio.h> | |
24 | #include <stdlib.h> | |
25 | #include <string.h> | |
26 | #include <sys/wait.h> | |
27 | #include <sys/types.h> | |
28 | #include <sys/stat.h> | |
29 | #include <unistd.h> | |
30 | #include <fcntl.h> | |
c2b75c49 | 31 | #include <sched.h> |
730389d9 | 32 | #include <sys/signal.h> |
60b6c79c | 33 | |
90e535ef | 34 | #include <common/common.h> |
3fd15a74 | 35 | #include <common/utils.h> |
730389d9 DG |
36 | #include <common/compat/mman.h> |
37 | #include <common/compat/clone.h> | |
e8fa9fb0 | 38 | #include <common/compat/getenv.h> |
60b6c79c | 39 | |
0857097f DG |
40 | #include "runas.h" |
41 | ||
e11d277b | 42 | #define RUNAS_CHILD_STACK_SIZE 10485760 |
c2b75c49 | 43 | |
1e4035fc AS |
44 | #ifndef MAP_STACK |
45 | #define MAP_STACK 0 | |
46 | #endif | |
47 | ||
0756d557 MD |
48 | #ifdef __FreeBSD__ |
49 | /* FreeBSD MAP_STACK always return -ENOMEM */ | |
50 | #define LTTNG_MAP_STACK 0 | |
51 | #else | |
52 | #define LTTNG_MAP_STACK MAP_STACK | |
059e1d3d MD |
53 | #endif |
54 | ||
a5ae566a | 55 | #ifndef MAP_GROWSDOWN |
edb025e8 | 56 | #define MAP_GROWSDOWN 0 |
a5ae566a MD |
57 | #endif |
58 | ||
59 | #ifndef MAP_ANONYMOUS | |
60 | #define MAP_ANONYMOUS MAP_ANON | |
61 | #endif | |
62 | ||
c2b75c49 MD |
63 | struct run_as_data { |
64 | int (*cmd)(void *data); | |
65 | void *data; | |
66 | uid_t uid; | |
67 | gid_t gid; | |
68 | int retval_pipe; | |
69 | }; | |
70 | ||
e11d277b | 71 | struct run_as_mkdir_data { |
60b6c79c MD |
72 | const char *path; |
73 | mode_t mode; | |
74 | }; | |
75 | ||
e11d277b | 76 | struct run_as_open_data { |
60b6c79c MD |
77 | const char *path; |
78 | int flags; | |
79 | mode_t mode; | |
80 | }; | |
81 | ||
4628484a MD |
82 | struct run_as_unlink_data { |
83 | const char *path; | |
84 | }; | |
85 | ||
86 | struct run_as_recursive_rmdir_data { | |
87 | const char *path; | |
88 | }; | |
89 | ||
df5b86c8 MD |
90 | struct run_as_ret { |
91 | int ret; | |
92 | int _errno; | |
93 | }; | |
94 | ||
8f0044bf MD |
95 | #ifdef VALGRIND |
96 | static | |
97 | int use_clone(void) | |
98 | { | |
99 | return 0; | |
100 | } | |
101 | #else | |
102 | static | |
103 | int use_clone(void) | |
104 | { | |
e8fa9fb0 | 105 | return !lttng_secure_getenv("LTTNG_DEBUG_NOCLONE"); |
8f0044bf MD |
106 | } |
107 | #endif | |
108 | ||
d77dded2 JG |
109 | LTTNG_HIDDEN |
110 | int _utils_mkdir_recursive_unsafe(const char *path, mode_t mode); | |
111 | ||
60b6c79c MD |
112 | /* |
113 | * Create recursively directory using the FULL path. | |
114 | */ | |
115 | static | |
116 | int _mkdir_recursive(void *_data) | |
117 | { | |
e11d277b | 118 | struct run_as_mkdir_data *data = _data; |
60b6c79c | 119 | const char *path; |
60b6c79c | 120 | mode_t mode; |
60b6c79c MD |
121 | |
122 | path = data->path; | |
123 | mode = data->mode; | |
124 | ||
d77dded2 JG |
125 | /* Safe to call as we have transitioned to the requested uid/gid. */ |
126 | return _utils_mkdir_recursive_unsafe(path, mode); | |
60b6c79c MD |
127 | } |
128 | ||
129 | static | |
130 | int _mkdir(void *_data) | |
131 | { | |
e11d277b | 132 | struct run_as_mkdir_data *data = _data; |
7ce36756 | 133 | |
df5b86c8 | 134 | return mkdir(data->path, data->mode); |
60b6c79c MD |
135 | } |
136 | ||
137 | static | |
138 | int _open(void *_data) | |
139 | { | |
e11d277b | 140 | struct run_as_open_data *data = _data; |
df5b86c8 | 141 | |
60b6c79c MD |
142 | return open(data->path, data->flags, data->mode); |
143 | } | |
144 | ||
4628484a MD |
145 | static |
146 | int _unlink(void *_data) | |
147 | { | |
4628484a MD |
148 | struct run_as_unlink_data *data = _data; |
149 | ||
df5b86c8 | 150 | return unlink(data->path); |
4628484a MD |
151 | } |
152 | ||
153 | static | |
154 | int _recursive_rmdir(void *_data) | |
155 | { | |
4628484a MD |
156 | struct run_as_recursive_rmdir_data *data = _data; |
157 | ||
df5b86c8 | 158 | return utils_recursive_rmdir(data->path); |
4628484a MD |
159 | } |
160 | ||
c2b75c49 MD |
161 | static |
162 | int child_run_as(void *_data) | |
163 | { | |
6775595e | 164 | int ret; |
c2b75c49 | 165 | struct run_as_data *data = _data; |
6775595e | 166 | ssize_t writelen; |
df5b86c8 | 167 | struct run_as_ret sendret; |
c2b75c49 MD |
168 | |
169 | /* | |
170 | * Child: it is safe to drop egid and euid while sharing the | |
171 | * file descriptors with the parent process, since we do not | |
172 | * drop "uid": therefore, the user we are dropping egid/euid to | |
173 | * cannot attach to this process with, e.g. ptrace, nor map this | |
174 | * process memory. | |
175 | */ | |
1576d582 MD |
176 | if (data->gid != getegid()) { |
177 | ret = setegid(data->gid); | |
178 | if (ret < 0) { | |
4c462e79 | 179 | PERROR("setegid"); |
6d73c4ef | 180 | goto write_return; |
1576d582 | 181 | } |
c2b75c49 | 182 | } |
1576d582 MD |
183 | if (data->uid != geteuid()) { |
184 | ret = seteuid(data->uid); | |
185 | if (ret < 0) { | |
4c462e79 | 186 | PERROR("seteuid"); |
6d73c4ef | 187 | goto write_return; |
1576d582 | 188 | } |
c2b75c49 MD |
189 | } |
190 | /* | |
191 | * Also set umask to 0 for mkdir executable bit. | |
192 | */ | |
193 | umask(0); | |
df5b86c8 | 194 | ret = (*data->cmd)(data->data); |
6d73c4ef MD |
195 | |
196 | write_return: | |
df5b86c8 MD |
197 | sendret.ret = ret; |
198 | sendret._errno = errno; | |
c2b75c49 | 199 | /* send back return value */ |
6cd525e8 MD |
200 | writelen = lttng_write(data->retval_pipe, &sendret, sizeof(sendret)); |
201 | if (writelen < sizeof(sendret)) { | |
202 | PERROR("lttng_write error"); | |
203 | return EXIT_FAILURE; | |
204 | } else { | |
205 | return EXIT_SUCCESS; | |
206 | } | |
c2b75c49 MD |
207 | } |
208 | ||
60b6c79c | 209 | static |
2d85a600 | 210 | int run_as_clone(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid) |
60b6c79c | 211 | { |
c2b75c49 | 212 | struct run_as_data run_as_data; |
60b6c79c | 213 | int ret = 0; |
6cd525e8 | 214 | ssize_t readlen; |
c2b75c49 | 215 | int status; |
60b6c79c | 216 | pid_t pid; |
c2b75c49 | 217 | int retval_pipe[2]; |
d5bd7573 | 218 | void *child_stack; |
df5b86c8 | 219 | struct run_as_ret recvret; |
60b6c79c MD |
220 | |
221 | /* | |
222 | * If we are non-root, we can only deal with our own uid. | |
223 | */ | |
224 | if (geteuid() != 0) { | |
225 | if (uid != geteuid()) { | |
df5b86c8 MD |
226 | recvret.ret = -1; |
227 | recvret._errno = EPERM; | |
60b6c79c MD |
228 | ERR("Client (%d)/Server (%d) UID mismatch (and sessiond is not root)", |
229 | uid, geteuid()); | |
df5b86c8 | 230 | goto end; |
60b6c79c | 231 | } |
60b6c79c MD |
232 | } |
233 | ||
c2b75c49 MD |
234 | ret = pipe(retval_pipe); |
235 | if (ret < 0) { | |
df5b86c8 MD |
236 | recvret.ret = -1; |
237 | recvret._errno = errno; | |
4c462e79 | 238 | PERROR("pipe"); |
60b6c79c | 239 | goto end; |
c2b75c49 MD |
240 | } |
241 | run_as_data.data = data; | |
242 | run_as_data.cmd = cmd; | |
243 | run_as_data.uid = uid; | |
244 | run_as_data.gid = gid; | |
245 | run_as_data.retval_pipe = retval_pipe[1]; /* write end */ | |
e11d277b | 246 | child_stack = mmap(NULL, RUNAS_CHILD_STACK_SIZE, |
d5bd7573 | 247 | PROT_WRITE | PROT_READ, |
0756d557 | 248 | MAP_PRIVATE | MAP_GROWSDOWN | MAP_ANONYMOUS | LTTNG_MAP_STACK, |
d5bd7573 MD |
249 | -1, 0); |
250 | if (child_stack == MAP_FAILED) { | |
df5b86c8 MD |
251 | recvret.ret = -1; |
252 | recvret._errno = ENOMEM; | |
4c462e79 | 253 | PERROR("mmap"); |
d5bd7573 MD |
254 | goto close_pipe; |
255 | } | |
256 | /* | |
257 | * Pointing to the middle of the stack to support architectures | |
258 | * where the stack grows up (HPPA). | |
259 | */ | |
89831a74 MD |
260 | pid = lttng_clone_files(child_run_as, child_stack + (RUNAS_CHILD_STACK_SIZE / 2), |
261 | &run_as_data); | |
c2b75c49 | 262 | if (pid < 0) { |
df5b86c8 MD |
263 | recvret.ret = -1; |
264 | recvret._errno = errno; | |
4c462e79 | 265 | PERROR("clone"); |
d5bd7573 | 266 | goto unmap_stack; |
c2b75c49 MD |
267 | } |
268 | /* receive return value */ | |
df5b86c8 MD |
269 | readlen = lttng_read(retval_pipe[0], &recvret, sizeof(recvret)); |
270 | if (readlen < sizeof(recvret)) { | |
271 | recvret.ret = -1; | |
272 | recvret._errno = errno; | |
6cd525e8 | 273 | } |
c2b75c49 MD |
274 | |
275 | /* | |
276 | * Parent: wait for child to return, in which case the | |
277 | * shared memory map will have been created. | |
278 | */ | |
47fb7563 | 279 | pid = waitpid(pid, &status, 0); |
c2b75c49 | 280 | if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) { |
df5b86c8 MD |
281 | recvret.ret = -1; |
282 | recvret._errno = errno; | |
4c462e79 | 283 | PERROR("wait"); |
60b6c79c | 284 | } |
d5bd7573 | 285 | unmap_stack: |
e11d277b | 286 | ret = munmap(child_stack, RUNAS_CHILD_STACK_SIZE); |
d5bd7573 | 287 | if (ret < 0) { |
df5b86c8 MD |
288 | recvret.ret = -1; |
289 | recvret._errno = errno; | |
4c462e79 | 290 | PERROR("munmap"); |
d5bd7573 | 291 | } |
c2b75c49 | 292 | close_pipe: |
4c462e79 MD |
293 | ret = close(retval_pipe[0]); |
294 | if (ret) { | |
df5b86c8 MD |
295 | recvret.ret = -1; |
296 | recvret._errno = errno; | |
4c462e79 MD |
297 | PERROR("close"); |
298 | } | |
299 | ret = close(retval_pipe[1]); | |
300 | if (ret) { | |
df5b86c8 MD |
301 | recvret.ret = -1; |
302 | recvret._errno = errno; | |
4c462e79 MD |
303 | PERROR("close"); |
304 | } | |
60b6c79c | 305 | end: |
df5b86c8 MD |
306 | errno = recvret._errno; |
307 | return recvret.ret; | |
60b6c79c MD |
308 | } |
309 | ||
2d85a600 MD |
310 | /* |
311 | * To be used on setups where gdb has issues debugging programs using | |
312 | * clone/rfork. Note that this is for debuging ONLY, and should not be | |
313 | * considered secure. | |
314 | */ | |
315 | static | |
316 | int run_as_noclone(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid) | |
317 | { | |
df5b86c8 | 318 | int ret, saved_errno; |
5b73926f DG |
319 | mode_t old_mask; |
320 | ||
321 | old_mask = umask(0); | |
322 | ret = cmd(data); | |
df5b86c8 | 323 | saved_errno = errno; |
5b73926f | 324 | umask(old_mask); |
df5b86c8 | 325 | errno = saved_errno; |
5b73926f DG |
326 | |
327 | return ret; | |
2d85a600 MD |
328 | } |
329 | ||
330 | static | |
331 | int run_as(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid) | |
332 | { | |
8f0044bf | 333 | if (use_clone()) { |
9ef70f87 MD |
334 | int ret; |
335 | ||
2d85a600 | 336 | DBG("Using run_as_clone"); |
9ef70f87 MD |
337 | pthread_mutex_lock(<tng_libc_state_lock); |
338 | ret = run_as_clone(cmd, data, uid, gid); | |
339 | pthread_mutex_unlock(<tng_libc_state_lock); | |
340 | return ret; | |
2d85a600 MD |
341 | } else { |
342 | DBG("Using run_as_noclone"); | |
343 | return run_as_noclone(cmd, data, uid, gid); | |
344 | } | |
345 | } | |
346 | ||
90e535ef | 347 | LTTNG_HIDDEN |
e11d277b | 348 | int run_as_mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid) |
60b6c79c | 349 | { |
e11d277b | 350 | struct run_as_mkdir_data data; |
60b6c79c MD |
351 | |
352 | DBG3("mkdir() recursive %s with mode %d for uid %d and gid %d", | |
353 | path, mode, uid, gid); | |
354 | data.path = path; | |
355 | data.mode = mode; | |
356 | return run_as(_mkdir_recursive, &data, uid, gid); | |
357 | } | |
358 | ||
90e535ef | 359 | LTTNG_HIDDEN |
e11d277b | 360 | int run_as_mkdir(const char *path, mode_t mode, uid_t uid, gid_t gid) |
60b6c79c | 361 | { |
e11d277b | 362 | struct run_as_mkdir_data data; |
60b6c79c MD |
363 | |
364 | DBG3("mkdir() %s with mode %d for uid %d and gid %d", | |
365 | path, mode, uid, gid); | |
366 | data.path = path; | |
367 | data.mode = mode; | |
368 | return run_as(_mkdir, &data, uid, gid); | |
369 | } | |
370 | ||
371 | /* | |
372 | * Note: open_run_as is currently not working. We'd need to pass the fd | |
373 | * opened in the child to the parent. | |
374 | */ | |
90e535ef | 375 | LTTNG_HIDDEN |
e11d277b | 376 | int run_as_open(const char *path, int flags, mode_t mode, uid_t uid, gid_t gid) |
60b6c79c | 377 | { |
e11d277b | 378 | struct run_as_open_data data; |
c2b75c49 | 379 | |
47fb7563 MD |
380 | DBG3("open() %s with flags %X mode %d for uid %d and gid %d", |
381 | path, flags, mode, uid, gid); | |
60b6c79c MD |
382 | data.path = path; |
383 | data.flags = flags; | |
384 | data.mode = mode; | |
385 | return run_as(_open, &data, uid, gid); | |
60b6c79c | 386 | } |
4628484a MD |
387 | |
388 | LTTNG_HIDDEN | |
389 | int run_as_unlink(const char *path, uid_t uid, gid_t gid) | |
390 | { | |
391 | struct run_as_unlink_data data; | |
392 | ||
393 | DBG3("unlink() %s with for uid %d and gid %d", | |
394 | path, uid, gid); | |
395 | data.path = path; | |
396 | return run_as(_unlink, &data, uid, gid); | |
397 | } | |
398 | ||
399 | LTTNG_HIDDEN | |
400 | int run_as_recursive_rmdir(const char *path, uid_t uid, gid_t gid) | |
401 | { | |
402 | struct run_as_recursive_rmdir_data data; | |
403 | ||
404 | DBG3("recursive_rmdir() %s with for uid %d and gid %d", | |
405 | path, uid, gid); | |
406 | data.path = path; | |
407 | return run_as(_recursive_rmdir, &data, uid, gid); | |
408 | } |