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 | |
20 | #include <errno.h> | |
21 | #include <limits.h> | |
22 | #include <stdio.h> | |
23 | #include <stdlib.h> | |
24 | #include <string.h> | |
25 | #include <sys/wait.h> | |
26 | #include <sys/types.h> | |
27 | #include <sys/stat.h> | |
28 | #include <unistd.h> | |
29 | #include <fcntl.h> | |
c2b75c49 | 30 | #include <sched.h> |
730389d9 | 31 | #include <sys/signal.h> |
60b6c79c | 32 | |
90e535ef | 33 | #include <common/common.h> |
3fd15a74 | 34 | #include <common/utils.h> |
730389d9 DG |
35 | #include <common/compat/mman.h> |
36 | #include <common/compat/clone.h> | |
60b6c79c | 37 | |
0857097f DG |
38 | #include "runas.h" |
39 | ||
e11d277b | 40 | #define RUNAS_CHILD_STACK_SIZE 10485760 |
c2b75c49 | 41 | |
1e4035fc AS |
42 | #ifndef MAP_STACK |
43 | #define MAP_STACK 0 | |
44 | #endif | |
45 | ||
0756d557 MD |
46 | #ifdef __FreeBSD__ |
47 | /* FreeBSD MAP_STACK always return -ENOMEM */ | |
48 | #define LTTNG_MAP_STACK 0 | |
49 | #else | |
50 | #define LTTNG_MAP_STACK MAP_STACK | |
059e1d3d MD |
51 | #endif |
52 | ||
a5ae566a | 53 | #ifndef MAP_GROWSDOWN |
edb025e8 | 54 | #define MAP_GROWSDOWN 0 |
a5ae566a MD |
55 | #endif |
56 | ||
57 | #ifndef MAP_ANONYMOUS | |
58 | #define MAP_ANONYMOUS MAP_ANON | |
59 | #endif | |
60 | ||
c2b75c49 MD |
61 | struct run_as_data { |
62 | int (*cmd)(void *data); | |
63 | void *data; | |
64 | uid_t uid; | |
65 | gid_t gid; | |
66 | int retval_pipe; | |
67 | }; | |
68 | ||
e11d277b | 69 | struct run_as_mkdir_data { |
60b6c79c MD |
70 | const char *path; |
71 | mode_t mode; | |
72 | }; | |
73 | ||
e11d277b | 74 | struct run_as_open_data { |
60b6c79c MD |
75 | const char *path; |
76 | int flags; | |
77 | mode_t mode; | |
78 | }; | |
79 | ||
d92d258f JG |
80 | struct run_as_unlink_data { |
81 | const char *path; | |
82 | }; | |
83 | ||
4ffbac14 MD |
84 | struct run_as_ret { |
85 | int ret; | |
86 | int _errno; | |
87 | }; | |
88 | ||
8f0044bf MD |
89 | #ifdef VALGRIND |
90 | static | |
91 | int use_clone(void) | |
92 | { | |
93 | return 0; | |
94 | } | |
95 | #else | |
96 | static | |
97 | int use_clone(void) | |
98 | { | |
99 | return !getenv("LTTNG_DEBUG_NOCLONE"); | |
100 | } | |
101 | #endif | |
102 | ||
0d083fb8 JG |
103 | LTTNG_HIDDEN |
104 | int _utils_mkdir_recursive_unsafe(const char *path, mode_t mode); | |
105 | ||
60b6c79c MD |
106 | /* |
107 | * Create recursively directory using the FULL path. | |
108 | */ | |
109 | static | |
110 | int _mkdir_recursive(void *_data) | |
111 | { | |
e11d277b | 112 | struct run_as_mkdir_data *data = _data; |
60b6c79c | 113 | const char *path; |
60b6c79c | 114 | mode_t mode; |
60b6c79c MD |
115 | |
116 | path = data->path; | |
117 | mode = data->mode; | |
118 | ||
0d083fb8 JG |
119 | /* Safe to call as we have transitioned to the requested uid/gid. */ |
120 | return _utils_mkdir_recursive_unsafe(path, mode); | |
60b6c79c MD |
121 | } |
122 | ||
123 | static | |
124 | int _mkdir(void *_data) | |
125 | { | |
e11d277b | 126 | struct run_as_mkdir_data *data = _data; |
7ce36756 | 127 | |
4ffbac14 | 128 | return mkdir(data->path, data->mode); |
60b6c79c MD |
129 | } |
130 | ||
131 | static | |
132 | int _open(void *_data) | |
133 | { | |
e11d277b | 134 | struct run_as_open_data *data = _data; |
4ffbac14 | 135 | |
60b6c79c MD |
136 | return open(data->path, data->flags, data->mode); |
137 | } | |
138 | ||
d92d258f JG |
139 | static |
140 | int _unlink(void *_data) | |
141 | { | |
d92d258f JG |
142 | struct run_as_unlink_data *data = _data; |
143 | ||
4ffbac14 | 144 | return unlink(data->path); |
d92d258f JG |
145 | } |
146 | ||
c2b75c49 MD |
147 | static |
148 | int child_run_as(void *_data) | |
149 | { | |
6775595e | 150 | int ret; |
c2b75c49 | 151 | struct run_as_data *data = _data; |
6775595e | 152 | ssize_t writelen; |
4ffbac14 | 153 | struct run_as_ret sendret; |
c2b75c49 MD |
154 | |
155 | /* | |
156 | * Child: it is safe to drop egid and euid while sharing the | |
157 | * file descriptors with the parent process, since we do not | |
158 | * drop "uid": therefore, the user we are dropping egid/euid to | |
159 | * cannot attach to this process with, e.g. ptrace, nor map this | |
160 | * process memory. | |
161 | */ | |
1576d582 MD |
162 | if (data->gid != getegid()) { |
163 | ret = setegid(data->gid); | |
164 | if (ret < 0) { | |
4c462e79 | 165 | PERROR("setegid"); |
6d73c4ef | 166 | goto write_return; |
1576d582 | 167 | } |
c2b75c49 | 168 | } |
1576d582 MD |
169 | if (data->uid != geteuid()) { |
170 | ret = seteuid(data->uid); | |
171 | if (ret < 0) { | |
4c462e79 | 172 | PERROR("seteuid"); |
6d73c4ef | 173 | goto write_return; |
1576d582 | 174 | } |
c2b75c49 MD |
175 | } |
176 | /* | |
177 | * Also set umask to 0 for mkdir executable bit. | |
178 | */ | |
179 | umask(0); | |
4ffbac14 | 180 | ret = (*data->cmd)(data->data); |
6d73c4ef MD |
181 | |
182 | write_return: | |
4ffbac14 MD |
183 | sendret.ret = ret; |
184 | sendret._errno = errno; | |
c2b75c49 | 185 | /* send back return value */ |
6cd525e8 MD |
186 | writelen = lttng_write(data->retval_pipe, &sendret, sizeof(sendret)); |
187 | if (writelen < sizeof(sendret)) { | |
188 | PERROR("lttng_write error"); | |
189 | return EXIT_FAILURE; | |
190 | } else { | |
191 | return EXIT_SUCCESS; | |
192 | } | |
c2b75c49 MD |
193 | } |
194 | ||
60b6c79c | 195 | static |
2d85a600 | 196 | int run_as_clone(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid) |
60b6c79c | 197 | { |
c2b75c49 | 198 | struct run_as_data run_as_data; |
60b6c79c | 199 | int ret = 0; |
6cd525e8 | 200 | ssize_t readlen; |
c2b75c49 | 201 | int status; |
60b6c79c | 202 | pid_t pid; |
c2b75c49 | 203 | int retval_pipe[2]; |
d5bd7573 | 204 | void *child_stack; |
4ffbac14 | 205 | struct run_as_ret recvret; |
60b6c79c MD |
206 | |
207 | /* | |
208 | * If we are non-root, we can only deal with our own uid. | |
209 | */ | |
210 | if (geteuid() != 0) { | |
211 | if (uid != geteuid()) { | |
4ffbac14 MD |
212 | recvret.ret = -1; |
213 | recvret._errno = EPERM; | |
60b6c79c MD |
214 | ERR("Client (%d)/Server (%d) UID mismatch (and sessiond is not root)", |
215 | uid, geteuid()); | |
4ffbac14 | 216 | goto end; |
60b6c79c | 217 | } |
60b6c79c MD |
218 | } |
219 | ||
c2b75c49 MD |
220 | ret = pipe(retval_pipe); |
221 | if (ret < 0) { | |
4ffbac14 MD |
222 | recvret.ret = -1; |
223 | recvret._errno = errno; | |
4c462e79 | 224 | PERROR("pipe"); |
60b6c79c | 225 | goto end; |
c2b75c49 MD |
226 | } |
227 | run_as_data.data = data; | |
228 | run_as_data.cmd = cmd; | |
229 | run_as_data.uid = uid; | |
230 | run_as_data.gid = gid; | |
231 | run_as_data.retval_pipe = retval_pipe[1]; /* write end */ | |
e11d277b | 232 | child_stack = mmap(NULL, RUNAS_CHILD_STACK_SIZE, |
d5bd7573 | 233 | PROT_WRITE | PROT_READ, |
0756d557 | 234 | MAP_PRIVATE | MAP_GROWSDOWN | MAP_ANONYMOUS | LTTNG_MAP_STACK, |
d5bd7573 MD |
235 | -1, 0); |
236 | if (child_stack == MAP_FAILED) { | |
4ffbac14 MD |
237 | recvret.ret = -1; |
238 | recvret._errno = ENOMEM; | |
4c462e79 | 239 | PERROR("mmap"); |
d5bd7573 MD |
240 | goto close_pipe; |
241 | } | |
242 | /* | |
243 | * Pointing to the middle of the stack to support architectures | |
244 | * where the stack grows up (HPPA). | |
245 | */ | |
89831a74 MD |
246 | pid = lttng_clone_files(child_run_as, child_stack + (RUNAS_CHILD_STACK_SIZE / 2), |
247 | &run_as_data); | |
c2b75c49 | 248 | if (pid < 0) { |
4ffbac14 MD |
249 | recvret.ret = -1; |
250 | recvret._errno = errno; | |
4c462e79 | 251 | PERROR("clone"); |
d5bd7573 | 252 | goto unmap_stack; |
c2b75c49 MD |
253 | } |
254 | /* receive return value */ | |
4ffbac14 MD |
255 | readlen = lttng_read(retval_pipe[0], &recvret, sizeof(recvret)); |
256 | if (readlen < sizeof(recvret)) { | |
257 | recvret.ret = -1; | |
258 | recvret._errno = errno; | |
6cd525e8 | 259 | } |
c2b75c49 MD |
260 | |
261 | /* | |
262 | * Parent: wait for child to return, in which case the | |
263 | * shared memory map will have been created. | |
264 | */ | |
47fb7563 | 265 | pid = waitpid(pid, &status, 0); |
c2b75c49 | 266 | if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) { |
4ffbac14 MD |
267 | recvret.ret = -1; |
268 | recvret._errno = errno; | |
4c462e79 | 269 | PERROR("wait"); |
60b6c79c | 270 | } |
d5bd7573 | 271 | unmap_stack: |
e11d277b | 272 | ret = munmap(child_stack, RUNAS_CHILD_STACK_SIZE); |
d5bd7573 | 273 | if (ret < 0) { |
4ffbac14 MD |
274 | recvret.ret = -1; |
275 | recvret._errno = errno; | |
4c462e79 | 276 | PERROR("munmap"); |
d5bd7573 | 277 | } |
c2b75c49 | 278 | close_pipe: |
4c462e79 MD |
279 | ret = close(retval_pipe[0]); |
280 | if (ret) { | |
4ffbac14 MD |
281 | recvret.ret = -1; |
282 | recvret._errno = errno; | |
4c462e79 MD |
283 | PERROR("close"); |
284 | } | |
285 | ret = close(retval_pipe[1]); | |
286 | if (ret) { | |
4ffbac14 MD |
287 | recvret.ret = -1; |
288 | recvret._errno = errno; | |
4c462e79 MD |
289 | PERROR("close"); |
290 | } | |
60b6c79c | 291 | end: |
4ffbac14 MD |
292 | errno = recvret._errno; |
293 | return recvret.ret; | |
60b6c79c MD |
294 | } |
295 | ||
2d85a600 MD |
296 | /* |
297 | * To be used on setups where gdb has issues debugging programs using | |
298 | * clone/rfork. Note that this is for debuging ONLY, and should not be | |
299 | * considered secure. | |
300 | */ | |
301 | static | |
302 | int run_as_noclone(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid) | |
303 | { | |
4ffbac14 | 304 | int ret, saved_errno; |
5b73926f DG |
305 | mode_t old_mask; |
306 | ||
307 | old_mask = umask(0); | |
308 | ret = cmd(data); | |
4ffbac14 | 309 | saved_errno = errno; |
5b73926f | 310 | umask(old_mask); |
4ffbac14 | 311 | errno = saved_errno; |
5b73926f DG |
312 | |
313 | return ret; | |
2d85a600 MD |
314 | } |
315 | ||
316 | static | |
317 | int run_as(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid) | |
318 | { | |
8f0044bf | 319 | if (use_clone()) { |
9ef70f87 MD |
320 | int ret; |
321 | ||
2d85a600 | 322 | DBG("Using run_as_clone"); |
9ef70f87 MD |
323 | pthread_mutex_lock(<tng_libc_state_lock); |
324 | ret = run_as_clone(cmd, data, uid, gid); | |
325 | pthread_mutex_unlock(<tng_libc_state_lock); | |
326 | return ret; | |
2d85a600 MD |
327 | } else { |
328 | DBG("Using run_as_noclone"); | |
329 | return run_as_noclone(cmd, data, uid, gid); | |
330 | } | |
331 | } | |
332 | ||
90e535ef | 333 | LTTNG_HIDDEN |
e11d277b | 334 | int run_as_mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid) |
60b6c79c | 335 | { |
e11d277b | 336 | struct run_as_mkdir_data data; |
60b6c79c MD |
337 | |
338 | DBG3("mkdir() recursive %s with mode %d for uid %d and gid %d", | |
339 | path, mode, uid, gid); | |
340 | data.path = path; | |
341 | data.mode = mode; | |
342 | return run_as(_mkdir_recursive, &data, uid, gid); | |
343 | } | |
344 | ||
90e535ef | 345 | LTTNG_HIDDEN |
e11d277b | 346 | int run_as_mkdir(const char *path, mode_t mode, uid_t uid, gid_t gid) |
60b6c79c | 347 | { |
e11d277b | 348 | struct run_as_mkdir_data data; |
60b6c79c MD |
349 | |
350 | DBG3("mkdir() %s with mode %d for uid %d and gid %d", | |
351 | path, mode, uid, gid); | |
352 | data.path = path; | |
353 | data.mode = mode; | |
354 | return run_as(_mkdir, &data, uid, gid); | |
355 | } | |
356 | ||
357 | /* | |
358 | * Note: open_run_as is currently not working. We'd need to pass the fd | |
359 | * opened in the child to the parent. | |
360 | */ | |
90e535ef | 361 | LTTNG_HIDDEN |
e11d277b | 362 | int run_as_open(const char *path, int flags, mode_t mode, uid_t uid, gid_t gid) |
60b6c79c | 363 | { |
e11d277b | 364 | struct run_as_open_data data; |
c2b75c49 | 365 | |
47fb7563 MD |
366 | DBG3("open() %s with flags %X mode %d for uid %d and gid %d", |
367 | path, flags, mode, uid, gid); | |
60b6c79c MD |
368 | data.path = path; |
369 | data.flags = flags; | |
370 | data.mode = mode; | |
371 | return run_as(_open, &data, uid, gid); | |
60b6c79c | 372 | } |
d92d258f JG |
373 | |
374 | LTTNG_HIDDEN | |
375 | int run_as_unlink(const char *path, uid_t uid, gid_t gid) | |
376 | { | |
377 | struct run_as_unlink_data data; | |
378 | ||
379 | DBG3("unlink() %s with for uid %d and gid %d", | |
380 | path, uid, gid); | |
381 | data.path = path; | |
382 | return run_as(_unlink, &data, uid, gid); | |
383 | } |