Commit | Line | Data |
---|---|---|
e822f505 | 1 | /* |
c0c0989a MJ |
2 | * SPDX-License-Identifier: LGPL-2.1-only |
3 | * | |
e822f505 | 4 | * Copyright (C) 2009 Pierre-Marc Fournier |
3678c8aa | 5 | * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
2d99476b PMF |
6 | */ |
7 | ||
9d315d6d MJ |
8 | /* Has to be included first to override dlfcn.h */ |
9 | #include <common/compat/dlfcn.h> | |
10 | ||
2d99476b | 11 | #include <unistd.h> |
8b27b287 | 12 | #include <stdbool.h> |
2d99476b | 13 | #include <stdio.h> |
df793c55 | 14 | #include <signal.h> |
616ed36a PMF |
15 | #include <sched.h> |
16 | #include <stdarg.h> | |
e2a195a6 | 17 | #include <stdlib.h> |
eb2b066f | 18 | #include <errno.h> |
2d99476b | 19 | |
8b27b287 OD |
20 | #include <pthread.h> |
21 | ||
d0c8f180 | 22 | #include <lttng/ust-fork.h> |
e822f505 | 23 | |
cf54f06a OD |
24 | #include <urcu/uatomic.h> |
25 | ||
8b27b287 OD |
26 | #include "common/macros.h" |
27 | ||
28 | struct libc_pointer { | |
29 | void **procedure; | |
30 | const char *symbol; | |
31 | }; | |
32 | ||
33 | #define DEFINE_LIBC_POINTER(name) { (void**)&plibc_## name, #name } | |
34 | ||
35 | #ifdef __linux__ | |
36 | ||
37 | struct user_desc; | |
38 | ||
39 | static int (*plibc_clone)(int (*fn)(void *), void *child_stack, | |
40 | int flags, void *arg, pid_t *ptid, | |
41 | struct user_desc *tls, pid_t *ctid) = NULL; | |
42 | ||
43 | static int (*plibc_setns)(int fd, int nstype) = NULL; | |
44 | ||
45 | static int (*plibc_setresgid)(gid_t rgid, gid_t egid, gid_t sgid) = NULL; | |
46 | ||
47 | static int (*plibc_setresuid)(uid_t ruid, uid_t euid, uid_t suid) = NULL; | |
48 | ||
49 | static int (*plibc_unshare)(int flags) = NULL; | |
50 | ||
51 | #elif defined (__FreeBSD__) | |
52 | ||
53 | static pid_t (*plibc_rfork)(int flags) = NULL; | |
54 | ||
55 | #endif | |
56 | ||
57 | static int (*plibc_daemon)(int nochdir, int noclose) = NULL; | |
58 | ||
59 | static pid_t (*plibc_fork)(void) = NULL; | |
60 | ||
61 | static int (*plibc_setegid)(gid_t egid) = NULL; | |
62 | ||
63 | static int (*plibc_seteuid)(uid_t euid) = NULL; | |
64 | ||
65 | static int (*plibc_setgid)(gid_t gid) = NULL; | |
66 | ||
67 | static int (*plibc_setregid)(gid_t rgid, gid_t egid) = NULL; | |
68 | ||
69 | static int (*plibc_setreuid)(uid_t ruid, uid_t euid) = NULL; | |
70 | ||
71 | static int (*plibc_setuid)(uid_t uid) = NULL; | |
72 | ||
73 | static void lttng_ust_fork_wrapper_ctor(void) | |
74 | __attribute__((constructor)); | |
75 | ||
76 | static pthread_mutex_t initialization_guard = PTHREAD_MUTEX_INITIALIZER; | |
77 | static bool was_initialized = false; | |
78 | ||
79 | /* | |
80 | * Must be called with initialization_guard held. | |
81 | */ | |
82 | static void initialize(void) | |
83 | { | |
84 | const struct libc_pointer libc_pointers[] = { | |
85 | #ifdef __linux__ | |
86 | DEFINE_LIBC_POINTER(clone), | |
87 | DEFINE_LIBC_POINTER(setns), | |
88 | DEFINE_LIBC_POINTER(setresgid), | |
89 | DEFINE_LIBC_POINTER(setresuid), | |
90 | DEFINE_LIBC_POINTER(unshare), | |
91 | #elif defined (__FreeBSD__) | |
92 | DEFINE_LIBC_POINTER(rfork), | |
93 | #endif | |
94 | DEFINE_LIBC_POINTER(daemon), | |
95 | DEFINE_LIBC_POINTER(fork), | |
96 | DEFINE_LIBC_POINTER(setegid), | |
97 | DEFINE_LIBC_POINTER(seteuid), | |
98 | DEFINE_LIBC_POINTER(setgid), | |
99 | DEFINE_LIBC_POINTER(setregid), | |
100 | DEFINE_LIBC_POINTER(setreuid), | |
101 | DEFINE_LIBC_POINTER(setuid), | |
102 | }; | |
103 | ||
104 | size_t k; | |
105 | ||
106 | for (k = 0; k < LTTNG_ARRAY_SIZE(libc_pointers); ++k) { | |
107 | void *procedure = dlsym(RTLD_NEXT, libc_pointers[k].symbol); | |
108 | ||
109 | if (NULL == procedure) { | |
110 | fprintf(stderr, | |
111 | "libustfork: unable to find \"%s\" symbol\n", | |
112 | libc_pointers[k].symbol); | |
113 | continue; | |
114 | } | |
115 | ||
116 | uatomic_set(libc_pointers[k].procedure, procedure); | |
117 | } | |
118 | } | |
119 | ||
120 | /* | |
121 | * Lazy initialization is required because it is possible for a shared library | |
122 | * to have a constructor that is executed before our constructor, which could | |
123 | * call some libc functions that we are wrapping. | |
124 | * | |
125 | * It is also possible for this library constructor to create a thread using the | |
126 | * raw system call. Therefore, the lazy initialization must be multi-thread safe. | |
127 | */ | |
128 | static void *lazy_initialize(void **pfunc) | |
129 | { | |
130 | void *func = uatomic_read(pfunc); | |
131 | ||
132 | /* | |
133 | * If *pfunc != NULL, then it is assumed that some thread has already | |
134 | * called the initialization routine. | |
135 | */ | |
136 | if (caa_likely(func)) { | |
137 | goto out; | |
138 | } | |
139 | ||
140 | pthread_mutex_lock(&initialization_guard); | |
141 | if (!was_initialized) { | |
142 | initialize(); | |
143 | was_initialized = true; | |
144 | } | |
145 | func = *pfunc; | |
146 | pthread_mutex_unlock(&initialization_guard); | |
147 | out: | |
148 | return func; | |
149 | } | |
150 | ||
151 | #define LAZY_INITIALIZE_OR_NOSYS(ptr) \ | |
152 | ({ \ | |
153 | void *ret; \ | |
154 | \ | |
155 | ret = lazy_initialize((void**)&(ptr)); \ | |
156 | if (NULL == ret) { \ | |
157 | errno = ENOSYS; \ | |
158 | return -1; \ | |
159 | } \ | |
160 | \ | |
161 | ret; \ | |
162 | }) | |
163 | ||
164 | static void lttng_ust_fork_wrapper_ctor(void) | |
165 | { | |
166 | /* | |
167 | * Using fork here because it is defined on all supported OS. | |
168 | */ | |
169 | (void) lazy_initialize((void**)&plibc_fork); | |
170 | } | |
171 | ||
2d99476b PMF |
172 | pid_t fork(void) |
173 | { | |
7f0aeeba | 174 | sigset_t sigset; |
2d99476b | 175 | pid_t retval; |
111902ab | 176 | int saved_errno; |
2d99476b | 177 | |
8b27b287 | 178 | pid_t (*func)(void) = LAZY_INITIALIZE_OR_NOSYS(plibc_fork); |
2d99476b | 179 | |
d0c8f180 | 180 | lttng_ust_before_fork(&sigset); |
df793c55 | 181 | /* Do the real fork */ |
cf54f06a | 182 | retval = func(); |
111902ab | 183 | saved_errno = errno; |
e822f505 | 184 | if (retval == 0) { |
df793c55 | 185 | /* child */ |
d0c8f180 | 186 | lttng_ust_after_fork_child(&sigset); |
e822f505 | 187 | } else { |
d0c8f180 | 188 | lttng_ust_after_fork_parent(&sigset); |
df793c55 | 189 | } |
111902ab | 190 | errno = saved_errno; |
2d99476b PMF |
191 | return retval; |
192 | } | |
97b042a3 | 193 | |
2f6150e9 MD |
194 | int daemon(int nochdir, int noclose) |
195 | { | |
2f6150e9 MD |
196 | sigset_t sigset; |
197 | int retval; | |
111902ab | 198 | int saved_errno; |
2f6150e9 | 199 | |
8b27b287 | 200 | int (*func)(int, int) = LAZY_INITIALIZE_OR_NOSYS(plibc_daemon); |
2f6150e9 | 201 | |
d0c8f180 | 202 | lttng_ust_before_fork(&sigset); |
2f6150e9 | 203 | /* Do the real daemon call */ |
cf54f06a | 204 | retval = func(nochdir, noclose); |
111902ab | 205 | saved_errno = errno; |
2f6150e9 MD |
206 | if (retval == 0) { |
207 | /* child, parent called _exit() directly */ | |
d0c8f180 | 208 | lttng_ust_after_fork_child(&sigset); |
2f6150e9 MD |
209 | } else { |
210 | /* on error in the parent */ | |
d0c8f180 | 211 | lttng_ust_after_fork_parent(&sigset); |
2f6150e9 | 212 | } |
111902ab | 213 | errno = saved_errno; |
2f6150e9 MD |
214 | return retval; |
215 | } | |
216 | ||
fca2f191 MJ |
217 | int setuid(uid_t uid) |
218 | { | |
fca2f191 MJ |
219 | int retval; |
220 | int saved_errno; | |
221 | ||
8b27b287 | 222 | int (*func)(uid_t) = LAZY_INITIALIZE_OR_NOSYS(plibc_setuid); |
fca2f191 MJ |
223 | |
224 | /* Do the real setuid */ | |
cf54f06a | 225 | retval = func(uid); |
fca2f191 MJ |
226 | saved_errno = errno; |
227 | ||
d0c8f180 | 228 | lttng_ust_after_setuid(); |
fca2f191 MJ |
229 | |
230 | errno = saved_errno; | |
231 | return retval; | |
232 | } | |
233 | ||
234 | int setgid(gid_t gid) | |
235 | { | |
fca2f191 MJ |
236 | int retval; |
237 | int saved_errno; | |
238 | ||
8b27b287 | 239 | int (*func)(gid_t) = LAZY_INITIALIZE_OR_NOSYS(plibc_setgid); |
fca2f191 MJ |
240 | |
241 | /* Do the real setgid */ | |
cf54f06a | 242 | retval = func(gid); |
fca2f191 MJ |
243 | saved_errno = errno; |
244 | ||
d0c8f180 | 245 | lttng_ust_after_setgid(); |
fca2f191 MJ |
246 | |
247 | errno = saved_errno; | |
248 | return retval; | |
249 | } | |
250 | ||
251 | int seteuid(uid_t euid) | |
252 | { | |
fca2f191 MJ |
253 | int retval; |
254 | int saved_errno; | |
255 | ||
8b27b287 | 256 | int (*func)(uid_t) = LAZY_INITIALIZE_OR_NOSYS(plibc_seteuid); |
fca2f191 MJ |
257 | |
258 | /* Do the real seteuid */ | |
cf54f06a | 259 | retval = func(euid); |
fca2f191 MJ |
260 | saved_errno = errno; |
261 | ||
d0c8f180 | 262 | lttng_ust_after_seteuid(); |
fca2f191 MJ |
263 | |
264 | errno = saved_errno; | |
265 | return retval; | |
266 | } | |
267 | ||
268 | int setegid(gid_t egid) | |
269 | { | |
fca2f191 MJ |
270 | int retval; |
271 | int saved_errno; | |
272 | ||
8b27b287 | 273 | int (*func)(gid_t) = LAZY_INITIALIZE_OR_NOSYS(plibc_setegid); |
fca2f191 MJ |
274 | |
275 | /* Do the real setegid */ | |
cf54f06a | 276 | retval = func(egid); |
fca2f191 MJ |
277 | saved_errno = errno; |
278 | ||
d0c8f180 | 279 | lttng_ust_after_setegid(); |
fca2f191 MJ |
280 | |
281 | errno = saved_errno; | |
282 | return retval; | |
283 | } | |
284 | ||
285 | int setreuid(uid_t ruid, uid_t euid) | |
286 | { | |
fca2f191 MJ |
287 | int retval; |
288 | int saved_errno; | |
289 | ||
8b27b287 OD |
290 | int (*func)(uid_t, uid_t) = |
291 | LAZY_INITIALIZE_OR_NOSYS(plibc_setreuid); | |
fca2f191 MJ |
292 | |
293 | /* Do the real setreuid */ | |
cf54f06a | 294 | retval = func(ruid, euid); |
fca2f191 MJ |
295 | saved_errno = errno; |
296 | ||
d0c8f180 | 297 | lttng_ust_after_setreuid(); |
fca2f191 MJ |
298 | |
299 | errno = saved_errno; | |
300 | return retval; | |
301 | } | |
302 | ||
303 | int setregid(gid_t rgid, gid_t egid) | |
304 | { | |
fca2f191 MJ |
305 | int retval; |
306 | int saved_errno; | |
307 | ||
8b27b287 | 308 | int (*func)(gid_t, gid_t) = LAZY_INITIALIZE_OR_NOSYS(plibc_setregid); |
fca2f191 MJ |
309 | |
310 | /* Do the real setregid */ | |
cf54f06a | 311 | retval = func(rgid, egid); |
fca2f191 MJ |
312 | saved_errno = errno; |
313 | ||
d0c8f180 | 314 | lttng_ust_after_setregid(); |
fca2f191 MJ |
315 | |
316 | errno = saved_errno; | |
317 | return retval; | |
318 | } | |
319 | ||
939c89cb MD |
320 | #ifdef __linux__ |
321 | ||
e822f505 | 322 | struct ustfork_clone_info { |
616ed36a PMF |
323 | int (*fn)(void *); |
324 | void *arg; | |
7f0aeeba | 325 | sigset_t sigset; |
616ed36a PMF |
326 | }; |
327 | ||
328 | static int clone_fn(void *arg) | |
329 | { | |
e822f505 | 330 | struct ustfork_clone_info *info = (struct ustfork_clone_info *) arg; |
616ed36a PMF |
331 | |
332 | /* clone is now done and we are in child */ | |
d0c8f180 | 333 | lttng_ust_after_fork_child(&info->sigset); |
616ed36a PMF |
334 | return info->fn(info->arg); |
335 | } | |
336 | ||
337 | int clone(int (*fn)(void *), void *child_stack, int flags, void *arg, ...) | |
338 | { | |
e822f505 | 339 | /* var args */ |
616ed36a PMF |
340 | pid_t *ptid; |
341 | struct user_desc *tls; | |
342 | pid_t *ctid; | |
e822f505 | 343 | /* end of var args */ |
616ed36a | 344 | va_list ap; |
e822f505 | 345 | int retval; |
111902ab | 346 | int saved_errno; |
616ed36a PMF |
347 | |
348 | va_start(ap, arg); | |
349 | ptid = va_arg(ap, pid_t *); | |
350 | tls = va_arg(ap, struct user_desc *); | |
351 | ctid = va_arg(ap, pid_t *); | |
352 | va_end(ap); | |
353 | ||
8b27b287 OD |
354 | int (*func)(int (*)(void *), void *, int , void *, pid_t *, |
355 | struct user_desc *, pid_t *) = | |
356 | LAZY_INITIALIZE_OR_NOSYS(plibc_clone); | |
616ed36a | 357 | |
e822f505 MD |
358 | if (flags & CLONE_VM) { |
359 | /* | |
360 | * Creating a thread, no need to intervene, just pass on | |
361 | * the arguments. | |
362 | */ | |
cf54f06a OD |
363 | retval = func(fn, child_stack, flags, arg, ptid, |
364 | tls, ctid); | |
111902ab | 365 | saved_errno = errno; |
e822f505 MD |
366 | } else { |
367 | /* Creating a real process, we need to intervene. */ | |
3fd2b913 | 368 | struct ustfork_clone_info info = { .fn = fn, .arg = arg }; |
616ed36a | 369 | |
d0c8f180 | 370 | lttng_ust_before_fork(&info.sigset); |
cf54f06a OD |
371 | retval = func(clone_fn, child_stack, flags, &info, |
372 | ptid, tls, ctid); | |
111902ab | 373 | saved_errno = errno; |
e822f505 | 374 | /* The child doesn't get here. */ |
d0c8f180 | 375 | lttng_ust_after_fork_parent(&info.sigset); |
616ed36a | 376 | } |
111902ab | 377 | errno = saved_errno; |
616ed36a PMF |
378 | return retval; |
379 | } | |
939c89cb | 380 | |
735bef47 MJ |
381 | int setns(int fd, int nstype) |
382 | { | |
735bef47 MJ |
383 | int retval; |
384 | int saved_errno; | |
385 | ||
8b27b287 | 386 | int (*func)(int, int) = LAZY_INITIALIZE_OR_NOSYS(plibc_setns); |
735bef47 MJ |
387 | |
388 | /* Do the real setns */ | |
cf54f06a | 389 | retval = func(fd, nstype); |
735bef47 MJ |
390 | saved_errno = errno; |
391 | ||
d0c8f180 | 392 | lttng_ust_after_setns(); |
735bef47 MJ |
393 | |
394 | errno = saved_errno; | |
395 | return retval; | |
396 | } | |
397 | ||
398 | int unshare(int flags) | |
399 | { | |
735bef47 MJ |
400 | int retval; |
401 | int saved_errno; | |
402 | ||
8b27b287 | 403 | int (*func)(int) = LAZY_INITIALIZE_OR_NOSYS(plibc_unshare); |
735bef47 MJ |
404 | |
405 | /* Do the real setns */ | |
cf54f06a | 406 | retval = func(flags); |
735bef47 MJ |
407 | saved_errno = errno; |
408 | ||
d0c8f180 | 409 | lttng_ust_after_unshare(); |
735bef47 MJ |
410 | |
411 | errno = saved_errno; | |
412 | return retval; | |
413 | } | |
414 | ||
fca2f191 MJ |
415 | int setresuid(uid_t ruid, uid_t euid, uid_t suid) |
416 | { | |
fca2f191 MJ |
417 | int retval; |
418 | int saved_errno; | |
419 | ||
8b27b287 OD |
420 | int (*func)(uid_t, uid_t, uid_t) = |
421 | LAZY_INITIALIZE_OR_NOSYS(plibc_setresuid); | |
fca2f191 MJ |
422 | |
423 | /* Do the real setresuid */ | |
cf54f06a | 424 | retval = func(ruid, euid, suid); |
fca2f191 MJ |
425 | saved_errno = errno; |
426 | ||
d0c8f180 | 427 | lttng_ust_after_setresuid(); |
fca2f191 MJ |
428 | |
429 | errno = saved_errno; | |
430 | return retval; | |
431 | } | |
432 | ||
433 | int setresgid(gid_t rgid, gid_t egid, gid_t sgid) | |
434 | { | |
fca2f191 MJ |
435 | int retval; |
436 | int saved_errno; | |
437 | ||
8b27b287 OD |
438 | int (*func)(gid_t, gid_t, gid_t) = |
439 | LAZY_INITIALIZE_OR_NOSYS(plibc_setresgid); | |
fca2f191 MJ |
440 | |
441 | /* Do the real setresgid */ | |
cf54f06a | 442 | retval = func(rgid, egid, sgid); |
fca2f191 MJ |
443 | saved_errno = errno; |
444 | ||
d0c8f180 | 445 | lttng_ust_after_setresgid(); |
fca2f191 MJ |
446 | |
447 | errno = saved_errno; | |
448 | return retval; | |
449 | } | |
450 | ||
939c89cb MD |
451 | #elif defined (__FreeBSD__) |
452 | ||
453 | pid_t rfork(int flags) | |
454 | { | |
939c89cb MD |
455 | sigset_t sigset; |
456 | pid_t retval; | |
111902ab | 457 | int saved_errno; |
939c89cb | 458 | |
8b27b287 | 459 | pid_t (*func)(int) = LAZY_INITIALIZE_OR_NOSYS(plibc_rfork); |
939c89cb | 460 | |
d0c8f180 | 461 | lttng_ust_before_fork(&sigset); |
939c89cb | 462 | /* Do the real rfork */ |
cf54f06a | 463 | retval = func(flags); |
111902ab | 464 | saved_errno = errno; |
939c89cb MD |
465 | if (retval == 0) { |
466 | /* child */ | |
d0c8f180 | 467 | lttng_ust_after_fork_child(&sigset); |
939c89cb | 468 | } else { |
d0c8f180 | 469 | lttng_ust_after_fork_parent(&sigset); |
939c89cb | 470 | } |
111902ab | 471 | errno = saved_errno; |
939c89cb MD |
472 | return retval; |
473 | } | |
474 | ||
475 | /* | |
476 | * On BSD, no need to override vfork, because it runs in the context of | |
477 | * the parent, with parent waiting until execve or exit is executed in | |
478 | * the child. | |
479 | */ | |
480 | ||
481 | #else | |
482 | #warning "Unknown OS. You might want to ensure that fork/clone/vfork/fork handling is complete." | |
483 | #endif |