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 | ||
8f0044bf MD |
80 | #ifdef VALGRIND |
81 | static | |
82 | int use_clone(void) | |
83 | { | |
84 | return 0; | |
85 | } | |
86 | #else | |
87 | static | |
88 | int use_clone(void) | |
89 | { | |
90 | return !getenv("LTTNG_DEBUG_NOCLONE"); | |
91 | } | |
92 | #endif | |
93 | ||
0d083fb8 JG |
94 | LTTNG_HIDDEN |
95 | int _utils_mkdir_recursive_unsafe(const char *path, mode_t mode); | |
96 | ||
60b6c79c MD |
97 | /* |
98 | * Create recursively directory using the FULL path. | |
99 | */ | |
100 | static | |
101 | int _mkdir_recursive(void *_data) | |
102 | { | |
e11d277b | 103 | struct run_as_mkdir_data *data = _data; |
60b6c79c | 104 | const char *path; |
60b6c79c | 105 | mode_t mode; |
60b6c79c MD |
106 | |
107 | path = data->path; | |
108 | mode = data->mode; | |
109 | ||
0d083fb8 JG |
110 | /* Safe to call as we have transitioned to the requested uid/gid. */ |
111 | return _utils_mkdir_recursive_unsafe(path, mode); | |
60b6c79c MD |
112 | } |
113 | ||
114 | static | |
115 | int _mkdir(void *_data) | |
116 | { | |
7ce36756 | 117 | int ret; |
e11d277b | 118 | struct run_as_mkdir_data *data = _data; |
7ce36756 DG |
119 | |
120 | ret = mkdir(data->path, data->mode); | |
121 | if (ret < 0) { | |
122 | ret = -errno; | |
123 | } | |
124 | ||
125 | return ret; | |
60b6c79c MD |
126 | } |
127 | ||
128 | static | |
129 | int _open(void *_data) | |
130 | { | |
e11d277b | 131 | struct run_as_open_data *data = _data; |
60b6c79c MD |
132 | return open(data->path, data->flags, data->mode); |
133 | } | |
134 | ||
c2b75c49 MD |
135 | static |
136 | int child_run_as(void *_data) | |
137 | { | |
6775595e | 138 | int ret; |
c2b75c49 | 139 | struct run_as_data *data = _data; |
6775595e | 140 | ssize_t writelen; |
6cd525e8 | 141 | int sendret; |
c2b75c49 MD |
142 | |
143 | /* | |
144 | * Child: it is safe to drop egid and euid while sharing the | |
145 | * file descriptors with the parent process, since we do not | |
146 | * drop "uid": therefore, the user we are dropping egid/euid to | |
147 | * cannot attach to this process with, e.g. ptrace, nor map this | |
148 | * process memory. | |
149 | */ | |
1576d582 MD |
150 | if (data->gid != getegid()) { |
151 | ret = setegid(data->gid); | |
152 | if (ret < 0) { | |
4c462e79 | 153 | PERROR("setegid"); |
6cd525e8 | 154 | sendret = -1; |
6d73c4ef | 155 | goto write_return; |
1576d582 | 156 | } |
c2b75c49 | 157 | } |
1576d582 MD |
158 | if (data->uid != geteuid()) { |
159 | ret = seteuid(data->uid); | |
160 | if (ret < 0) { | |
4c462e79 | 161 | PERROR("seteuid"); |
6cd525e8 | 162 | sendret = -1; |
6d73c4ef | 163 | goto write_return; |
1576d582 | 164 | } |
c2b75c49 MD |
165 | } |
166 | /* | |
167 | * Also set umask to 0 for mkdir executable bit. | |
168 | */ | |
169 | umask(0); | |
6cd525e8 | 170 | sendret = (*data->cmd)(data->data); |
6d73c4ef MD |
171 | |
172 | write_return: | |
c2b75c49 | 173 | /* send back return value */ |
6cd525e8 MD |
174 | writelen = lttng_write(data->retval_pipe, &sendret, sizeof(sendret)); |
175 | if (writelen < sizeof(sendret)) { | |
176 | PERROR("lttng_write error"); | |
177 | return EXIT_FAILURE; | |
178 | } else { | |
179 | return EXIT_SUCCESS; | |
180 | } | |
c2b75c49 MD |
181 | } |
182 | ||
60b6c79c | 183 | static |
2d85a600 | 184 | int run_as_clone(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid) |
60b6c79c | 185 | { |
c2b75c49 | 186 | struct run_as_data run_as_data; |
60b6c79c | 187 | int ret = 0; |
6cd525e8 | 188 | ssize_t readlen; |
c2b75c49 | 189 | int status; |
60b6c79c | 190 | pid_t pid; |
c2b75c49 | 191 | int retval_pipe[2]; |
d5bd7573 | 192 | void *child_stack; |
6cd525e8 | 193 | int retval; |
60b6c79c MD |
194 | |
195 | /* | |
196 | * If we are non-root, we can only deal with our own uid. | |
197 | */ | |
198 | if (geteuid() != 0) { | |
199 | if (uid != geteuid()) { | |
200 | ERR("Client (%d)/Server (%d) UID mismatch (and sessiond is not root)", | |
201 | uid, geteuid()); | |
202 | return -EPERM; | |
203 | } | |
60b6c79c MD |
204 | } |
205 | ||
c2b75c49 MD |
206 | ret = pipe(retval_pipe); |
207 | if (ret < 0) { | |
4c462e79 | 208 | PERROR("pipe"); |
6cd525e8 | 209 | retval = ret; |
60b6c79c | 210 | goto end; |
c2b75c49 MD |
211 | } |
212 | run_as_data.data = data; | |
213 | run_as_data.cmd = cmd; | |
214 | run_as_data.uid = uid; | |
215 | run_as_data.gid = gid; | |
216 | run_as_data.retval_pipe = retval_pipe[1]; /* write end */ | |
e11d277b | 217 | child_stack = mmap(NULL, RUNAS_CHILD_STACK_SIZE, |
d5bd7573 | 218 | PROT_WRITE | PROT_READ, |
0756d557 | 219 | MAP_PRIVATE | MAP_GROWSDOWN | MAP_ANONYMOUS | LTTNG_MAP_STACK, |
d5bd7573 MD |
220 | -1, 0); |
221 | if (child_stack == MAP_FAILED) { | |
4c462e79 | 222 | PERROR("mmap"); |
6cd525e8 | 223 | retval = -ENOMEM; |
d5bd7573 MD |
224 | goto close_pipe; |
225 | } | |
226 | /* | |
227 | * Pointing to the middle of the stack to support architectures | |
228 | * where the stack grows up (HPPA). | |
229 | */ | |
89831a74 MD |
230 | pid = lttng_clone_files(child_run_as, child_stack + (RUNAS_CHILD_STACK_SIZE / 2), |
231 | &run_as_data); | |
c2b75c49 | 232 | if (pid < 0) { |
4c462e79 | 233 | PERROR("clone"); |
6cd525e8 | 234 | retval = pid; |
d5bd7573 | 235 | goto unmap_stack; |
c2b75c49 MD |
236 | } |
237 | /* receive return value */ | |
6cd525e8 MD |
238 | readlen = lttng_read(retval_pipe[0], &retval, sizeof(retval)); |
239 | if (readlen < sizeof(retval)) { | |
240 | ret = -1; | |
241 | } | |
c2b75c49 MD |
242 | |
243 | /* | |
244 | * Parent: wait for child to return, in which case the | |
245 | * shared memory map will have been created. | |
246 | */ | |
47fb7563 | 247 | pid = waitpid(pid, &status, 0); |
c2b75c49 | 248 | if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) { |
4c462e79 | 249 | PERROR("wait"); |
6cd525e8 | 250 | retval = -1; |
60b6c79c | 251 | } |
d5bd7573 | 252 | unmap_stack: |
e11d277b | 253 | ret = munmap(child_stack, RUNAS_CHILD_STACK_SIZE); |
d5bd7573 | 254 | if (ret < 0) { |
4c462e79 | 255 | PERROR("munmap"); |
6cd525e8 | 256 | retval = ret; |
d5bd7573 | 257 | } |
c2b75c49 | 258 | close_pipe: |
4c462e79 MD |
259 | ret = close(retval_pipe[0]); |
260 | if (ret) { | |
261 | PERROR("close"); | |
262 | } | |
263 | ret = close(retval_pipe[1]); | |
264 | if (ret) { | |
265 | PERROR("close"); | |
266 | } | |
60b6c79c | 267 | end: |
6cd525e8 | 268 | return retval; |
60b6c79c MD |
269 | } |
270 | ||
2d85a600 MD |
271 | /* |
272 | * To be used on setups where gdb has issues debugging programs using | |
273 | * clone/rfork. Note that this is for debuging ONLY, and should not be | |
274 | * considered secure. | |
275 | */ | |
276 | static | |
277 | int run_as_noclone(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid) | |
278 | { | |
5b73926f DG |
279 | int ret; |
280 | mode_t old_mask; | |
281 | ||
282 | old_mask = umask(0); | |
283 | ret = cmd(data); | |
284 | umask(old_mask); | |
285 | ||
286 | return ret; | |
2d85a600 MD |
287 | } |
288 | ||
289 | static | |
290 | int run_as(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid) | |
291 | { | |
8f0044bf | 292 | if (use_clone()) { |
9ef70f87 MD |
293 | int ret; |
294 | ||
2d85a600 | 295 | DBG("Using run_as_clone"); |
9ef70f87 MD |
296 | pthread_mutex_lock(<tng_libc_state_lock); |
297 | ret = run_as_clone(cmd, data, uid, gid); | |
298 | pthread_mutex_unlock(<tng_libc_state_lock); | |
299 | return ret; | |
2d85a600 MD |
300 | } else { |
301 | DBG("Using run_as_noclone"); | |
302 | return run_as_noclone(cmd, data, uid, gid); | |
303 | } | |
304 | } | |
305 | ||
90e535ef | 306 | LTTNG_HIDDEN |
e11d277b | 307 | int run_as_mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid) |
60b6c79c | 308 | { |
e11d277b | 309 | struct run_as_mkdir_data data; |
60b6c79c MD |
310 | |
311 | DBG3("mkdir() recursive %s with mode %d for uid %d and gid %d", | |
312 | path, mode, uid, gid); | |
313 | data.path = path; | |
314 | data.mode = mode; | |
315 | return run_as(_mkdir_recursive, &data, uid, gid); | |
316 | } | |
317 | ||
90e535ef | 318 | LTTNG_HIDDEN |
e11d277b | 319 | int run_as_mkdir(const char *path, mode_t mode, uid_t uid, gid_t gid) |
60b6c79c | 320 | { |
e11d277b | 321 | struct run_as_mkdir_data data; |
60b6c79c MD |
322 | |
323 | DBG3("mkdir() %s with mode %d for uid %d and gid %d", | |
324 | path, mode, uid, gid); | |
325 | data.path = path; | |
326 | data.mode = mode; | |
327 | return run_as(_mkdir, &data, uid, gid); | |
328 | } | |
329 | ||
330 | /* | |
331 | * Note: open_run_as is currently not working. We'd need to pass the fd | |
332 | * opened in the child to the parent. | |
333 | */ | |
90e535ef | 334 | LTTNG_HIDDEN |
e11d277b | 335 | int run_as_open(const char *path, int flags, mode_t mode, uid_t uid, gid_t gid) |
60b6c79c | 336 | { |
e11d277b | 337 | struct run_as_open_data data; |
c2b75c49 | 338 | |
47fb7563 MD |
339 | DBG3("open() %s with flags %X mode %d for uid %d and gid %d", |
340 | path, flags, mode, uid, gid); | |
60b6c79c MD |
341 | data.path = path; |
342 | data.flags = flags; | |
343 | data.mode = mode; | |
344 | return run_as(_open, &data, uid, gid); | |
60b6c79c | 345 | } |