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 | |
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 | ||
80 | /* | |
81 | * Create recursively directory using the FULL path. | |
82 | */ | |
83 | static | |
84 | int _mkdir_recursive(void *_data) | |
85 | { | |
e11d277b | 86 | struct run_as_mkdir_data *data = _data; |
60b6c79c | 87 | const char *path; |
60b6c79c | 88 | mode_t mode; |
60b6c79c MD |
89 | |
90 | path = data->path; | |
91 | mode = data->mode; | |
92 | ||
3fd15a74 | 93 | return utils_mkdir_recursive(path, mode); |
60b6c79c MD |
94 | } |
95 | ||
96 | static | |
97 | int _mkdir(void *_data) | |
98 | { | |
e11d277b | 99 | struct run_as_mkdir_data *data = _data; |
60b6c79c MD |
100 | return mkdir(data->path, data->mode); |
101 | } | |
102 | ||
103 | static | |
104 | int _open(void *_data) | |
105 | { | |
e11d277b | 106 | struct run_as_open_data *data = _data; |
60b6c79c MD |
107 | return open(data->path, data->flags, data->mode); |
108 | } | |
109 | ||
c2b75c49 MD |
110 | static |
111 | int child_run_as(void *_data) | |
112 | { | |
6775595e | 113 | int ret; |
c2b75c49 | 114 | struct run_as_data *data = _data; |
6775595e DG |
115 | ssize_t writelen; |
116 | size_t writeleft, index; | |
c2b75c49 MD |
117 | union { |
118 | int i; | |
119 | char c[sizeof(int)]; | |
120 | } sendret; | |
c2b75c49 MD |
121 | |
122 | /* | |
123 | * Child: it is safe to drop egid and euid while sharing the | |
124 | * file descriptors with the parent process, since we do not | |
125 | * drop "uid": therefore, the user we are dropping egid/euid to | |
126 | * cannot attach to this process with, e.g. ptrace, nor map this | |
127 | * process memory. | |
128 | */ | |
1576d582 MD |
129 | if (data->gid != getegid()) { |
130 | ret = setegid(data->gid); | |
131 | if (ret < 0) { | |
4c462e79 | 132 | PERROR("setegid"); |
6d73c4ef MD |
133 | sendret.i = -1; |
134 | goto write_return; | |
1576d582 | 135 | } |
c2b75c49 | 136 | } |
1576d582 MD |
137 | if (data->uid != geteuid()) { |
138 | ret = seteuid(data->uid); | |
139 | if (ret < 0) { | |
4c462e79 | 140 | PERROR("seteuid"); |
6d73c4ef MD |
141 | sendret.i = -1; |
142 | goto write_return; | |
1576d582 | 143 | } |
c2b75c49 MD |
144 | } |
145 | /* | |
146 | * Also set umask to 0 for mkdir executable bit. | |
147 | */ | |
148 | umask(0); | |
149 | sendret.i = (*data->cmd)(data->data); | |
6d73c4ef MD |
150 | |
151 | write_return: | |
c2b75c49 MD |
152 | /* send back return value */ |
153 | writeleft = sizeof(sendret); | |
154 | index = 0; | |
155 | do { | |
6f94560a MD |
156 | do { |
157 | writelen = write(data->retval_pipe, &sendret.c[index], | |
158 | writeleft); | |
159 | } while (writelen < 0 && errno == EINTR); | |
c2b75c49 | 160 | if (writelen < 0) { |
4c462e79 | 161 | PERROR("write"); |
6da9f915 | 162 | return EXIT_FAILURE; |
c2b75c49 MD |
163 | } |
164 | writeleft -= writelen; | |
165 | index += writelen; | |
166 | } while (writeleft > 0); | |
6da9f915 | 167 | return EXIT_SUCCESS; |
c2b75c49 MD |
168 | } |
169 | ||
60b6c79c | 170 | static |
2d85a600 | 171 | int run_as_clone(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid) |
60b6c79c | 172 | { |
c2b75c49 | 173 | struct run_as_data run_as_data; |
60b6c79c | 174 | int ret = 0; |
c2b75c49 | 175 | int status; |
60b6c79c | 176 | pid_t pid; |
c2b75c49 MD |
177 | int retval_pipe[2]; |
178 | ssize_t readlen, readleft, index; | |
d5bd7573 | 179 | void *child_stack; |
c2b75c49 MD |
180 | union { |
181 | int i; | |
182 | char c[sizeof(int)]; | |
183 | } retval; | |
60b6c79c MD |
184 | |
185 | /* | |
186 | * If we are non-root, we can only deal with our own uid. | |
187 | */ | |
188 | if (geteuid() != 0) { | |
189 | if (uid != geteuid()) { | |
190 | ERR("Client (%d)/Server (%d) UID mismatch (and sessiond is not root)", | |
191 | uid, geteuid()); | |
192 | return -EPERM; | |
193 | } | |
60b6c79c MD |
194 | } |
195 | ||
c2b75c49 MD |
196 | ret = pipe(retval_pipe); |
197 | if (ret < 0) { | |
4c462e79 | 198 | PERROR("pipe"); |
def5e0e8 | 199 | retval.i = ret; |
60b6c79c | 200 | goto end; |
c2b75c49 MD |
201 | } |
202 | run_as_data.data = data; | |
203 | run_as_data.cmd = cmd; | |
204 | run_as_data.uid = uid; | |
205 | run_as_data.gid = gid; | |
206 | run_as_data.retval_pipe = retval_pipe[1]; /* write end */ | |
e11d277b | 207 | child_stack = mmap(NULL, RUNAS_CHILD_STACK_SIZE, |
d5bd7573 | 208 | PROT_WRITE | PROT_READ, |
0756d557 | 209 | MAP_PRIVATE | MAP_GROWSDOWN | MAP_ANONYMOUS | LTTNG_MAP_STACK, |
d5bd7573 MD |
210 | -1, 0); |
211 | if (child_stack == MAP_FAILED) { | |
4c462e79 | 212 | PERROR("mmap"); |
def5e0e8 | 213 | retval.i = -ENOMEM; |
d5bd7573 MD |
214 | goto close_pipe; |
215 | } | |
216 | /* | |
217 | * Pointing to the middle of the stack to support architectures | |
218 | * where the stack grows up (HPPA). | |
219 | */ | |
89831a74 MD |
220 | pid = lttng_clone_files(child_run_as, child_stack + (RUNAS_CHILD_STACK_SIZE / 2), |
221 | &run_as_data); | |
c2b75c49 | 222 | if (pid < 0) { |
4c462e79 | 223 | PERROR("clone"); |
def5e0e8 | 224 | retval.i = pid; |
d5bd7573 | 225 | goto unmap_stack; |
c2b75c49 MD |
226 | } |
227 | /* receive return value */ | |
228 | readleft = sizeof(retval); | |
229 | index = 0; | |
230 | do { | |
231 | readlen = read(retval_pipe[0], &retval.c[index], readleft); | |
232 | if (readlen < 0) { | |
4c462e79 | 233 | PERROR("read"); |
c2b75c49 MD |
234 | ret = -1; |
235 | break; | |
60b6c79c | 236 | } |
c2b75c49 MD |
237 | readleft -= readlen; |
238 | index += readlen; | |
239 | } while (readleft > 0); | |
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"); |
def5e0e8 | 248 | retval.i = -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"); |
def5e0e8 | 254 | retval.i = 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: |
c2b75c49 | 266 | return retval.i; |
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 | { | |
290 | if (!getenv("LTTNG_DEBUG_NOCLONE")) { | |
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 | } |