Commit | Line | Data |
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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 | ||
8f0044bf MD |
82 | #ifdef VALGRIND |
83 | static | |
84 | int use_clone(void) | |
85 | { | |
86 | return 0; | |
87 | } | |
88 | #else | |
89 | static | |
90 | int use_clone(void) | |
91 | { | |
e8fa9fb0 | 92 | return !lttng_secure_getenv("LTTNG_DEBUG_NOCLONE"); |
8f0044bf MD |
93 | } |
94 | #endif | |
95 | ||
60b6c79c MD |
96 | /* |
97 | * Create recursively directory using the FULL path. | |
98 | */ | |
99 | static | |
100 | int _mkdir_recursive(void *_data) | |
101 | { | |
e11d277b | 102 | struct run_as_mkdir_data *data = _data; |
60b6c79c | 103 | const char *path; |
60b6c79c | 104 | mode_t mode; |
60b6c79c MD |
105 | |
106 | path = data->path; | |
107 | mode = data->mode; | |
108 | ||
3fd15a74 | 109 | return utils_mkdir_recursive(path, mode); |
60b6c79c MD |
110 | } |
111 | ||
112 | static | |
113 | int _mkdir(void *_data) | |
114 | { | |
7ce36756 | 115 | int ret; |
e11d277b | 116 | struct run_as_mkdir_data *data = _data; |
7ce36756 DG |
117 | |
118 | ret = mkdir(data->path, data->mode); | |
119 | if (ret < 0) { | |
120 | ret = -errno; | |
121 | } | |
122 | ||
123 | return ret; | |
60b6c79c MD |
124 | } |
125 | ||
126 | static | |
127 | int _open(void *_data) | |
128 | { | |
e11d277b | 129 | struct run_as_open_data *data = _data; |
60b6c79c MD |
130 | return open(data->path, data->flags, data->mode); |
131 | } | |
132 | ||
c2b75c49 MD |
133 | static |
134 | int child_run_as(void *_data) | |
135 | { | |
6775595e | 136 | int ret; |
c2b75c49 | 137 | struct run_as_data *data = _data; |
6775595e | 138 | ssize_t writelen; |
6cd525e8 | 139 | int sendret; |
c2b75c49 MD |
140 | |
141 | /* | |
142 | * Child: it is safe to drop egid and euid while sharing the | |
143 | * file descriptors with the parent process, since we do not | |
144 | * drop "uid": therefore, the user we are dropping egid/euid to | |
145 | * cannot attach to this process with, e.g. ptrace, nor map this | |
146 | * process memory. | |
147 | */ | |
1576d582 MD |
148 | if (data->gid != getegid()) { |
149 | ret = setegid(data->gid); | |
150 | if (ret < 0) { | |
4c462e79 | 151 | PERROR("setegid"); |
6cd525e8 | 152 | sendret = -1; |
6d73c4ef | 153 | goto write_return; |
1576d582 | 154 | } |
c2b75c49 | 155 | } |
1576d582 MD |
156 | if (data->uid != geteuid()) { |
157 | ret = seteuid(data->uid); | |
158 | if (ret < 0) { | |
4c462e79 | 159 | PERROR("seteuid"); |
6cd525e8 | 160 | sendret = -1; |
6d73c4ef | 161 | goto write_return; |
1576d582 | 162 | } |
c2b75c49 MD |
163 | } |
164 | /* | |
165 | * Also set umask to 0 for mkdir executable bit. | |
166 | */ | |
167 | umask(0); | |
6cd525e8 | 168 | sendret = (*data->cmd)(data->data); |
6d73c4ef MD |
169 | |
170 | write_return: | |
c2b75c49 | 171 | /* send back return value */ |
6cd525e8 MD |
172 | writelen = lttng_write(data->retval_pipe, &sendret, sizeof(sendret)); |
173 | if (writelen < sizeof(sendret)) { | |
174 | PERROR("lttng_write error"); | |
175 | return EXIT_FAILURE; | |
176 | } else { | |
177 | return EXIT_SUCCESS; | |
178 | } | |
c2b75c49 MD |
179 | } |
180 | ||
60b6c79c | 181 | static |
2d85a600 | 182 | int run_as_clone(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid) |
60b6c79c | 183 | { |
c2b75c49 | 184 | struct run_as_data run_as_data; |
60b6c79c | 185 | int ret = 0; |
6cd525e8 | 186 | ssize_t readlen; |
c2b75c49 | 187 | int status; |
60b6c79c | 188 | pid_t pid; |
c2b75c49 | 189 | int retval_pipe[2]; |
d5bd7573 | 190 | void *child_stack; |
6cd525e8 | 191 | int retval; |
60b6c79c MD |
192 | |
193 | /* | |
194 | * If we are non-root, we can only deal with our own uid. | |
195 | */ | |
196 | if (geteuid() != 0) { | |
197 | if (uid != geteuid()) { | |
198 | ERR("Client (%d)/Server (%d) UID mismatch (and sessiond is not root)", | |
199 | uid, geteuid()); | |
200 | return -EPERM; | |
201 | } | |
60b6c79c MD |
202 | } |
203 | ||
c2b75c49 MD |
204 | ret = pipe(retval_pipe); |
205 | if (ret < 0) { | |
4c462e79 | 206 | PERROR("pipe"); |
6cd525e8 | 207 | retval = ret; |
60b6c79c | 208 | goto end; |
c2b75c49 MD |
209 | } |
210 | run_as_data.data = data; | |
211 | run_as_data.cmd = cmd; | |
212 | run_as_data.uid = uid; | |
213 | run_as_data.gid = gid; | |
214 | run_as_data.retval_pipe = retval_pipe[1]; /* write end */ | |
e11d277b | 215 | child_stack = mmap(NULL, RUNAS_CHILD_STACK_SIZE, |
d5bd7573 | 216 | PROT_WRITE | PROT_READ, |
0756d557 | 217 | MAP_PRIVATE | MAP_GROWSDOWN | MAP_ANONYMOUS | LTTNG_MAP_STACK, |
d5bd7573 MD |
218 | -1, 0); |
219 | if (child_stack == MAP_FAILED) { | |
4c462e79 | 220 | PERROR("mmap"); |
6cd525e8 | 221 | retval = -ENOMEM; |
d5bd7573 MD |
222 | goto close_pipe; |
223 | } | |
224 | /* | |
225 | * Pointing to the middle of the stack to support architectures | |
226 | * where the stack grows up (HPPA). | |
227 | */ | |
89831a74 MD |
228 | pid = lttng_clone_files(child_run_as, child_stack + (RUNAS_CHILD_STACK_SIZE / 2), |
229 | &run_as_data); | |
c2b75c49 | 230 | if (pid < 0) { |
4c462e79 | 231 | PERROR("clone"); |
6cd525e8 | 232 | retval = pid; |
d5bd7573 | 233 | goto unmap_stack; |
c2b75c49 MD |
234 | } |
235 | /* receive return value */ | |
6cd525e8 MD |
236 | readlen = lttng_read(retval_pipe[0], &retval, sizeof(retval)); |
237 | if (readlen < sizeof(retval)) { | |
238 | ret = -1; | |
239 | } | |
c2b75c49 MD |
240 | |
241 | /* | |
242 | * Parent: wait for child to return, in which case the | |
243 | * shared memory map will have been created. | |
244 | */ | |
47fb7563 | 245 | pid = waitpid(pid, &status, 0); |
c2b75c49 | 246 | if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) { |
4c462e79 | 247 | PERROR("wait"); |
6cd525e8 | 248 | retval = -1; |
60b6c79c | 249 | } |
d5bd7573 | 250 | unmap_stack: |
e11d277b | 251 | ret = munmap(child_stack, RUNAS_CHILD_STACK_SIZE); |
d5bd7573 | 252 | if (ret < 0) { |
4c462e79 | 253 | PERROR("munmap"); |
6cd525e8 | 254 | retval = ret; |
d5bd7573 | 255 | } |
c2b75c49 | 256 | close_pipe: |
4c462e79 MD |
257 | ret = close(retval_pipe[0]); |
258 | if (ret) { | |
259 | PERROR("close"); | |
260 | } | |
261 | ret = close(retval_pipe[1]); | |
262 | if (ret) { | |
263 | PERROR("close"); | |
264 | } | |
60b6c79c | 265 | end: |
6cd525e8 | 266 | return retval; |
60b6c79c MD |
267 | } |
268 | ||
2d85a600 MD |
269 | /* |
270 | * To be used on setups where gdb has issues debugging programs using | |
271 | * clone/rfork. Note that this is for debuging ONLY, and should not be | |
272 | * considered secure. | |
273 | */ | |
274 | static | |
275 | int run_as_noclone(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid) | |
276 | { | |
5b73926f DG |
277 | int ret; |
278 | mode_t old_mask; | |
279 | ||
280 | old_mask = umask(0); | |
281 | ret = cmd(data); | |
282 | umask(old_mask); | |
283 | ||
284 | return ret; | |
2d85a600 MD |
285 | } |
286 | ||
287 | static | |
288 | int run_as(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid) | |
289 | { | |
8f0044bf | 290 | if (use_clone()) { |
9ef70f87 MD |
291 | int ret; |
292 | ||
2d85a600 | 293 | DBG("Using run_as_clone"); |
9ef70f87 MD |
294 | pthread_mutex_lock(<tng_libc_state_lock); |
295 | ret = run_as_clone(cmd, data, uid, gid); | |
296 | pthread_mutex_unlock(<tng_libc_state_lock); | |
297 | return ret; | |
2d85a600 MD |
298 | } else { |
299 | DBG("Using run_as_noclone"); | |
300 | return run_as_noclone(cmd, data, uid, gid); | |
301 | } | |
302 | } | |
303 | ||
90e535ef | 304 | LTTNG_HIDDEN |
e11d277b | 305 | int run_as_mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid) |
60b6c79c | 306 | { |
e11d277b | 307 | struct run_as_mkdir_data data; |
60b6c79c MD |
308 | |
309 | DBG3("mkdir() recursive %s with mode %d for uid %d and gid %d", | |
310 | path, mode, uid, gid); | |
311 | data.path = path; | |
312 | data.mode = mode; | |
313 | return run_as(_mkdir_recursive, &data, uid, gid); | |
314 | } | |
315 | ||
90e535ef | 316 | LTTNG_HIDDEN |
e11d277b | 317 | int run_as_mkdir(const char *path, mode_t mode, uid_t uid, gid_t gid) |
60b6c79c | 318 | { |
e11d277b | 319 | struct run_as_mkdir_data data; |
60b6c79c MD |
320 | |
321 | DBG3("mkdir() %s with mode %d for uid %d and gid %d", | |
322 | path, mode, uid, gid); | |
323 | data.path = path; | |
324 | data.mode = mode; | |
325 | return run_as(_mkdir, &data, uid, gid); | |
326 | } | |
327 | ||
328 | /* | |
329 | * Note: open_run_as is currently not working. We'd need to pass the fd | |
330 | * opened in the child to the parent. | |
331 | */ | |
90e535ef | 332 | LTTNG_HIDDEN |
e11d277b | 333 | int run_as_open(const char *path, int flags, mode_t mode, uid_t uid, gid_t gid) |
60b6c79c | 334 | { |
e11d277b | 335 | struct run_as_open_data data; |
c2b75c49 | 336 | |
47fb7563 MD |
337 | DBG3("open() %s with flags %X mode %d for uid %d and gid %d", |
338 | path, flags, mode, uid, gid); | |
60b6c79c MD |
339 | data.path = path; |
340 | data.flags = flags; | |
341 | data.mode = mode; | |
342 | return run_as(_open, &data, uid, gid); | |
60b6c79c | 343 | } |