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6548fca4 MD |
1 | /* |
2 | * Copyright (C) 2016 - Aravind HT <aravind.ht@gmail.com> | |
3 | * 2016 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
4 | * | |
5 | * This library is free software; you can redistribute it and/or | |
6 | * modify it under the terms of the GNU Lesser General Public | |
7 | * License as published by the Free Software Foundation; only | |
8 | * version 2.1 of the License. | |
9 | * | |
10 | * This library is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | * Lesser General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU Lesser General Public | |
16 | * License along with this library; if not, write to the Free Software | |
17 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
18 | */ | |
19 | ||
20 | #define _GNU_SOURCE | |
21 | #include <limits.h> | |
22 | #include <stdio.h> | |
23 | #include <stdlib.h> | |
24 | #include <string.h> | |
25 | #include <sys/types.h> | |
26 | #include <unistd.h> | |
27 | #include <assert.h> | |
28 | #include <errno.h> | |
29 | #include <fcntl.h> | |
30 | #include <sys/select.h> | |
31 | #include <sys/resource.h> | |
32 | #include <sys/time.h> | |
33 | #include <fcntl.h> | |
34 | #include <pthread.h> | |
5932ab6f MD |
35 | #include <signal.h> |
36 | #include <stdbool.h> | |
6548fca4 MD |
37 | #include <urcu/compiler.h> |
38 | #include <urcu/tls-compat.h> | |
d5bfffd2 | 39 | #include <urcu/system.h> |
6548fca4 MD |
40 | |
41 | #include <ust-fd.h> | |
42 | #include <helper.h> | |
43 | #include <lttng/ust-error.h> | |
44 | #include <usterr-signal-safe.h> | |
45 | ||
46 | #include "../liblttng-ust/compat.h" | |
47 | ||
48 | /* Operations on the fd set. */ | |
49 | #define IS_FD_VALID(fd) ((fd) >= 0 && (fd) < lttng_ust_max_fd) | |
50 | #define GET_FD_SET_FOR_FD(fd, fd_sets) (&((fd_sets)[(fd) / FD_SETSIZE])) | |
51 | #define CALC_INDEX_TO_SET(fd) ((fd) % FD_SETSIZE) | |
0dd6b494 | 52 | #define IS_FD_STD(fd) (IS_FD_VALID(fd) && (fd) <= STDERR_FILENO) |
6548fca4 MD |
53 | |
54 | /* Check fd validity before calling these. */ | |
55 | #define ADD_FD_TO_SET(fd, fd_sets) \ | |
56 | FD_SET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
57 | #define IS_FD_SET(fd, fd_sets) \ | |
58 | FD_ISSET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
59 | #define DEL_FD_FROM_SET(fd, fd_sets) \ | |
60 | FD_CLR(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
61 | ||
62 | /* | |
63 | * Protect the lttng_fd_set. Nests within the ust_lock, and therefore | |
64 | * within the libc dl lock. Therefore, we need to fixup the TLS before | |
65 | * nesting into this lock. | |
791bf273 MD |
66 | * |
67 | * The ust_safe_guard_fd_mutex nests within the ust_mutex. This mutex | |
68 | * is also held across fork. | |
6548fca4 MD |
69 | */ |
70 | static pthread_mutex_t ust_safe_guard_fd_mutex = PTHREAD_MUTEX_INITIALIZER; | |
c97a0b6b MD |
71 | |
72 | /* | |
73 | * Cancel state when grabbing the ust_safe_guard_fd_mutex. Saved when | |
74 | * locking, restored on unlock. Protected by ust_safe_guard_fd_mutex. | |
75 | */ | |
76 | static int ust_safe_guard_saved_cancelstate; | |
77 | ||
6548fca4 MD |
78 | /* |
79 | * Track whether we are within lttng-ust or application, for close | |
ee6b2e66 MD |
80 | * system call override by LD_PRELOAD library. Threads registered |
81 | * as being lttng-ust listener threads need to perform fd tracker | |
82 | * locking explicitly around their use of file descriptor manipulation | |
83 | * functions. | |
84 | */ | |
85 | static DEFINE_URCU_TLS(int, thread_fd_tracking); | |
86 | ||
87 | /* | |
88 | * Track whether we are invoking close() from a signal handler nested on | |
89 | * an application thread. | |
6548fca4 | 90 | */ |
5932ab6f | 91 | static DEFINE_URCU_TLS(int, ust_fd_mutex_nest); |
6548fca4 | 92 | |
ee6b2e66 | 93 | |
6548fca4 MD |
94 | /* fd_set used to book keep fd being used by lttng-ust. */ |
95 | static fd_set *lttng_fd_set; | |
96 | static int lttng_ust_max_fd; | |
97 | static int num_fd_sets; | |
d5bfffd2 | 98 | static int init_done; |
6548fca4 MD |
99 | |
100 | /* | |
101 | * Force a read (imply TLS fixup for dlopen) of TLS variables. | |
102 | */ | |
103 | void lttng_ust_fixup_fd_tracker_tls(void) | |
104 | { | |
ee6b2e66 | 105 | asm volatile ("" : : "m" (URCU_TLS(thread_fd_tracking))); |
5932ab6f | 106 | asm volatile ("" : : "m" (URCU_TLS(ust_fd_mutex_nest))); |
6548fca4 MD |
107 | } |
108 | ||
109 | /* | |
110 | * Allocate the fd set array based on the hard limit set for this | |
111 | * process. This will be called during the constructor execution | |
112 | * and will also be called in the child after fork via lttng_ust_init. | |
113 | */ | |
114 | void lttng_ust_init_fd_tracker(void) | |
115 | { | |
116 | struct rlimit rlim; | |
117 | int i; | |
118 | ||
d5bfffd2 MD |
119 | if (CMM_LOAD_SHARED(init_done)) |
120 | return; | |
121 | ||
6548fca4 MD |
122 | memset(&rlim, 0, sizeof(rlim)); |
123 | /* Get the current possible max number of fd for this process. */ | |
124 | if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) | |
125 | abort(); | |
126 | /* | |
127 | * FD set array size determined using the hard limit. Even if | |
128 | * the process wishes to increase its limit using setrlimit, it | |
129 | * can only do so with the softlimit which will be less than the | |
130 | * hard limit. | |
131 | */ | |
132 | lttng_ust_max_fd = rlim.rlim_max; | |
133 | num_fd_sets = lttng_ust_max_fd / FD_SETSIZE; | |
134 | if (lttng_ust_max_fd % FD_SETSIZE) | |
135 | ++num_fd_sets; | |
136 | if (lttng_fd_set != NULL) { | |
137 | free(lttng_fd_set); | |
138 | lttng_fd_set = NULL; | |
139 | } | |
140 | lttng_fd_set = malloc(num_fd_sets * (sizeof(fd_set))); | |
141 | if (!lttng_fd_set) | |
142 | abort(); | |
143 | for (i = 0; i < num_fd_sets; i++) | |
144 | FD_ZERO((<tng_fd_set[i])); | |
d5bfffd2 | 145 | CMM_STORE_SHARED(init_done, 1); |
6548fca4 MD |
146 | } |
147 | ||
148 | void lttng_ust_lock_fd_tracker(void) | |
149 | { | |
5932ab6f | 150 | sigset_t sig_all_blocked, orig_mask; |
c97a0b6b MD |
151 | int ret, oldstate; |
152 | ||
153 | ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate); | |
154 | if (ret) { | |
155 | ERR("pthread_setcancelstate: %s", strerror(ret)); | |
156 | } | |
5932ab6f MD |
157 | sigfillset(&sig_all_blocked); |
158 | ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask); | |
159 | if (ret) { | |
160 | ERR("pthread_sigmask: %s", strerror(ret)); | |
161 | } | |
162 | if (!URCU_TLS(ust_fd_mutex_nest)++) { | |
163 | /* | |
164 | * Ensure the compiler don't move the store after the close() | |
165 | * call in case close() would be marked as leaf. | |
166 | */ | |
167 | cmm_barrier(); | |
168 | pthread_mutex_lock(&ust_safe_guard_fd_mutex); | |
169 | ust_safe_guard_saved_cancelstate = oldstate; | |
170 | } | |
171 | ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL); | |
172 | if (ret) { | |
173 | ERR("pthread_sigmask: %s", strerror(ret)); | |
174 | } | |
6548fca4 MD |
175 | } |
176 | ||
177 | void lttng_ust_unlock_fd_tracker(void) | |
178 | { | |
5932ab6f | 179 | sigset_t sig_all_blocked, orig_mask; |
c97a0b6b | 180 | int ret, newstate, oldstate; |
5932ab6f | 181 | bool restore_cancel = false; |
c97a0b6b | 182 | |
5932ab6f MD |
183 | sigfillset(&sig_all_blocked); |
184 | ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask); | |
185 | if (ret) { | |
186 | ERR("pthread_sigmask: %s", strerror(ret)); | |
187 | } | |
6548fca4 MD |
188 | /* |
189 | * Ensure the compiler don't move the store before the close() | |
190 | * call, in case close() would be marked as leaf. | |
191 | */ | |
192 | cmm_barrier(); | |
5932ab6f MD |
193 | if (!--URCU_TLS(ust_fd_mutex_nest)) { |
194 | newstate = ust_safe_guard_saved_cancelstate; | |
195 | restore_cancel = true; | |
196 | pthread_mutex_unlock(&ust_safe_guard_fd_mutex); | |
197 | } | |
198 | ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL); | |
c97a0b6b | 199 | if (ret) { |
5932ab6f MD |
200 | ERR("pthread_sigmask: %s", strerror(ret)); |
201 | } | |
202 | if (restore_cancel) { | |
203 | ret = pthread_setcancelstate(newstate, &oldstate); | |
204 | if (ret) { | |
205 | ERR("pthread_setcancelstate: %s", strerror(ret)); | |
206 | } | |
c97a0b6b | 207 | } |
6548fca4 MD |
208 | } |
209 | ||
0dd6b494 JR |
210 | static int dup_std_fd(int fd) |
211 | { | |
46e08d2c | 212 | int ret, i; |
0dd6b494 JR |
213 | int fd_to_close[STDERR_FILENO + 1]; |
214 | int fd_to_close_count = 0; | |
215 | int dup_cmd = F_DUPFD; /* Default command */ | |
216 | int fd_valid = -1; | |
217 | ||
218 | if (!(IS_FD_STD(fd))) { | |
219 | /* Should not be here */ | |
220 | ret = -1; | |
221 | goto error; | |
222 | } | |
223 | ||
224 | /* Check for FD_CLOEXEC flag */ | |
225 | ret = fcntl(fd, F_GETFD); | |
226 | if (ret < 0) { | |
227 | PERROR("fcntl on f_getfd"); | |
228 | ret = -1; | |
229 | goto error; | |
230 | } | |
231 | ||
232 | if (ret & FD_CLOEXEC) { | |
233 | dup_cmd = F_DUPFD_CLOEXEC; | |
234 | } | |
235 | ||
236 | /* Perform dup */ | |
46e08d2c | 237 | for (i = 0; i < STDERR_FILENO + 1; i++) { |
0dd6b494 JR |
238 | ret = fcntl(fd, dup_cmd, 0); |
239 | if (ret < 0) { | |
240 | PERROR("fcntl dup fd"); | |
241 | goto error; | |
242 | } | |
243 | ||
244 | if (!(IS_FD_STD(ret))) { | |
245 | /* fd is outside of STD range, use it. */ | |
246 | fd_valid = ret; | |
247 | /* Close fd received as argument. */ | |
248 | fd_to_close[i] = fd; | |
249 | fd_to_close_count++; | |
250 | break; | |
251 | } | |
252 | ||
253 | fd_to_close[i] = ret; | |
254 | fd_to_close_count++; | |
255 | } | |
256 | ||
257 | /* Close intermediary fds */ | |
46e08d2c | 258 | for (i = 0; i < fd_to_close_count; i++) { |
0dd6b494 JR |
259 | ret = close(fd_to_close[i]); |
260 | if (ret) { | |
261 | PERROR("close on temporary fd: %d.", fd_to_close[i]); | |
262 | /* | |
263 | * Not using an abort here would yield a complicated | |
264 | * error handling for the caller. If a failure occurs | |
265 | * here, the system is already in a bad state. | |
266 | */ | |
267 | abort(); | |
268 | } | |
269 | } | |
270 | ||
271 | ret = fd_valid; | |
272 | error: | |
273 | return ret; | |
274 | } | |
275 | ||
6548fca4 MD |
276 | /* |
277 | * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd. | |
278 | * Has strict checking of fd validity. | |
0dd6b494 JR |
279 | * |
280 | * If fd <= 2, dup the fd until fd > 2. This enables us to bypass | |
281 | * problems that can be encountered if UST uses stdin, stdout, stderr | |
282 | * fds for internal use (daemon etc.). This can happen if the | |
283 | * application closes either of those file descriptors. Intermediary fds | |
284 | * are closed as needed. | |
285 | * | |
286 | * Return -1 on error. | |
287 | * | |
6548fca4 | 288 | */ |
0dd6b494 | 289 | int lttng_ust_add_fd_to_tracker(int fd) |
6548fca4 | 290 | { |
0dd6b494 | 291 | int ret; |
d5bfffd2 MD |
292 | /* |
293 | * Ensure the tracker is initialized when called from | |
294 | * constructors. | |
295 | */ | |
296 | lttng_ust_init_fd_tracker(); | |
5932ab6f | 297 | assert(URCU_TLS(ust_fd_mutex_nest)); |
0dd6b494 JR |
298 | |
299 | if (IS_FD_STD(fd)) { | |
300 | ret = dup_std_fd(fd); | |
301 | if (ret < 0) { | |
302 | goto error; | |
303 | } | |
304 | fd = ret; | |
305 | } | |
306 | ||
6548fca4 MD |
307 | /* Trying to add an fd which we can not accommodate. */ |
308 | assert(IS_FD_VALID(fd)); | |
309 | /* Setting an fd thats already set. */ | |
310 | assert(!IS_FD_SET(fd, lttng_fd_set)); | |
311 | ||
312 | ADD_FD_TO_SET(fd, lttng_fd_set); | |
0dd6b494 JR |
313 | return fd; |
314 | error: | |
315 | return ret; | |
6548fca4 MD |
316 | } |
317 | ||
318 | /* | |
319 | * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd. | |
320 | * Has strict checking for fd validity. | |
321 | */ | |
322 | void lttng_ust_delete_fd_from_tracker(int fd) | |
323 | { | |
d5bfffd2 MD |
324 | /* |
325 | * Ensure the tracker is initialized when called from | |
326 | * constructors. | |
327 | */ | |
328 | lttng_ust_init_fd_tracker(); | |
329 | ||
5932ab6f | 330 | assert(URCU_TLS(ust_fd_mutex_nest)); |
6548fca4 MD |
331 | /* Not a valid fd. */ |
332 | assert(IS_FD_VALID(fd)); | |
333 | /* Deleting an fd which was not set. */ | |
334 | assert(IS_FD_SET(fd, lttng_fd_set)); | |
335 | ||
336 | DEL_FD_FROM_SET(fd, lttng_fd_set); | |
337 | } | |
338 | ||
339 | /* | |
340 | * Interface allowing applications to close arbitrary file descriptors. | |
341 | * We check if it is owned by lttng-ust, and return -1, errno=EBADF | |
342 | * instead of closing it if it is the case. | |
343 | */ | |
344 | int lttng_ust_safe_close_fd(int fd, int (*close_cb)(int fd)) | |
345 | { | |
346 | int ret = 0; | |
347 | ||
348 | lttng_ust_fixup_fd_tracker_tls(); | |
349 | ||
d5bfffd2 MD |
350 | /* |
351 | * Ensure the tracker is initialized when called from | |
352 | * constructors. | |
353 | */ | |
354 | lttng_ust_init_fd_tracker(); | |
355 | ||
6548fca4 MD |
356 | /* |
357 | * If called from lttng-ust, we directly call close without | |
358 | * validating whether the FD is part of the tracked set. | |
359 | */ | |
ee6b2e66 | 360 | if (URCU_TLS(thread_fd_tracking)) |
6548fca4 MD |
361 | return close_cb(fd); |
362 | ||
363 | lttng_ust_lock_fd_tracker(); | |
364 | if (IS_FD_VALID(fd) && IS_FD_SET(fd, lttng_fd_set)) { | |
365 | ret = -1; | |
366 | errno = EBADF; | |
367 | } else { | |
368 | ret = close_cb(fd); | |
369 | } | |
370 | lttng_ust_unlock_fd_tracker(); | |
371 | ||
372 | return ret; | |
373 | } | |
374 | ||
1b865e7e MD |
375 | /* |
376 | * Interface allowing applications to close arbitrary streams. | |
377 | * We check if it is owned by lttng-ust, and return -1, errno=EBADF | |
378 | * instead of closing it if it is the case. | |
379 | */ | |
380 | int lttng_ust_safe_fclose_stream(FILE *stream, int (*fclose_cb)(FILE *stream)) | |
381 | { | |
382 | int ret = 0, fd; | |
383 | ||
384 | lttng_ust_fixup_fd_tracker_tls(); | |
385 | ||
d5bfffd2 MD |
386 | /* |
387 | * Ensure the tracker is initialized when called from | |
388 | * constructors. | |
389 | */ | |
390 | lttng_ust_init_fd_tracker(); | |
391 | ||
1b865e7e MD |
392 | /* |
393 | * If called from lttng-ust, we directly call fclose without | |
394 | * validating whether the FD is part of the tracked set. | |
395 | */ | |
ee6b2e66 | 396 | if (URCU_TLS(thread_fd_tracking)) |
1b865e7e MD |
397 | return fclose_cb(stream); |
398 | ||
399 | fd = fileno(stream); | |
400 | ||
401 | lttng_ust_lock_fd_tracker(); | |
402 | if (IS_FD_VALID(fd) && IS_FD_SET(fd, lttng_fd_set)) { | |
403 | ret = -1; | |
404 | errno = EBADF; | |
405 | } else { | |
406 | ret = fclose_cb(stream); | |
407 | } | |
408 | lttng_ust_unlock_fd_tracker(); | |
409 | ||
410 | return ret; | |
411 | } | |
412 | ||
6548fca4 MD |
413 | #ifdef __OpenBSD__ |
414 | static void set_close_success(int *p) | |
415 | { | |
416 | *p = 1; | |
417 | } | |
418 | static int test_close_success(const int *p) | |
419 | { | |
420 | return *p; | |
421 | } | |
422 | #else | |
423 | static void set_close_success(int *p __attribute__((unused))) | |
424 | { | |
425 | } | |
426 | static int test_close_success(const int *p __attribute__((unused))) | |
427 | { | |
428 | return 1; | |
429 | } | |
430 | #endif | |
431 | ||
432 | /* | |
433 | * Implement helper for closefrom() override. | |
434 | */ | |
435 | int lttng_ust_safe_closefrom_fd(int lowfd, int (*close_cb)(int fd)) | |
436 | { | |
437 | int ret = 0, close_success = 0, i; | |
438 | ||
439 | lttng_ust_fixup_fd_tracker_tls(); | |
440 | ||
d5bfffd2 MD |
441 | /* |
442 | * Ensure the tracker is initialized when called from | |
443 | * constructors. | |
444 | */ | |
445 | lttng_ust_init_fd_tracker(); | |
446 | ||
6548fca4 MD |
447 | if (lowfd < 0) { |
448 | /* | |
449 | * NetBSD return EBADF if fd is invalid. | |
450 | */ | |
451 | errno = EBADF; | |
452 | ret = -1; | |
453 | goto end; | |
454 | } | |
455 | /* | |
456 | * If called from lttng-ust, we directly call close without | |
457 | * validating whether the FD is part of the tracked set. | |
458 | */ | |
ee6b2e66 | 459 | if (URCU_TLS(thread_fd_tracking)) { |
6548fca4 MD |
460 | for (i = lowfd; i < lttng_ust_max_fd; i++) { |
461 | if (close_cb(i) < 0) { | |
462 | switch (errno) { | |
463 | case EBADF: | |
464 | continue; | |
465 | case EINTR: | |
466 | default: | |
467 | ret = -1; | |
468 | goto end; | |
469 | } | |
470 | } | |
471 | set_close_success(&close_success); | |
472 | } | |
473 | } else { | |
474 | lttng_ust_lock_fd_tracker(); | |
475 | for (i = lowfd; i < lttng_ust_max_fd; i++) { | |
476 | if (IS_FD_VALID(i) && IS_FD_SET(i, lttng_fd_set)) | |
477 | continue; | |
478 | if (close_cb(i) < 0) { | |
479 | switch (errno) { | |
480 | case EBADF: | |
481 | continue; | |
482 | case EINTR: | |
483 | default: | |
484 | ret = -1; | |
485 | lttng_ust_unlock_fd_tracker(); | |
486 | goto end; | |
487 | } | |
488 | } | |
489 | set_close_success(&close_success); | |
490 | } | |
491 | lttng_ust_unlock_fd_tracker(); | |
492 | } | |
493 | if (!test_close_success(&close_success)) { | |
494 | /* | |
495 | * OpenBSD return EBADF if fd is greater than all open | |
496 | * file descriptors. | |
497 | */ | |
498 | ret = -1; | |
499 | errno = EBADF; | |
500 | } | |
501 | end: | |
502 | return ret; | |
503 | } | |
ee6b2e66 MD |
504 | |
505 | void lttng_ust_fd_tracker_register_thread(void) | |
506 | { | |
507 | URCU_TLS(thread_fd_tracking) = 1; | |
508 | } |