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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> | |
96a6162e MD |
35 | #include <signal.h> |
36 | #include <stdbool.h> | |
6548fca4 MD |
37 | #include <urcu/compiler.h> |
38 | #include <urcu/tls-compat.h> | |
7d34f27d | 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> | |
595c1577 | 45 | #include <lttng/ust-cancelstate.h> |
6548fca4 MD |
46 | |
47 | #include "../liblttng-ust/compat.h" | |
48 | ||
49 | /* Operations on the fd set. */ | |
50 | #define IS_FD_VALID(fd) ((fd) >= 0 && (fd) < lttng_ust_max_fd) | |
51 | #define GET_FD_SET_FOR_FD(fd, fd_sets) (&((fd_sets)[(fd) / FD_SETSIZE])) | |
52 | #define CALC_INDEX_TO_SET(fd) ((fd) % FD_SETSIZE) | |
f5c453e9 | 53 | #define IS_FD_STD(fd) (IS_FD_VALID(fd) && (fd) <= STDERR_FILENO) |
6548fca4 MD |
54 | |
55 | /* Check fd validity before calling these. */ | |
56 | #define ADD_FD_TO_SET(fd, fd_sets) \ | |
57 | FD_SET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
58 | #define IS_FD_SET(fd, fd_sets) \ | |
59 | FD_ISSET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
60 | #define DEL_FD_FROM_SET(fd, fd_sets) \ | |
61 | FD_CLR(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
62 | ||
63 | /* | |
64 | * Protect the lttng_fd_set. Nests within the ust_lock, and therefore | |
65 | * within the libc dl lock. Therefore, we need to fixup the TLS before | |
66 | * nesting into this lock. | |
c1be081a MD |
67 | * |
68 | * The ust_safe_guard_fd_mutex nests within the ust_mutex. This mutex | |
69 | * is also held across fork. | |
6548fca4 MD |
70 | */ |
71 | static pthread_mutex_t ust_safe_guard_fd_mutex = PTHREAD_MUTEX_INITIALIZER; | |
283f4bec | 72 | |
6548fca4 MD |
73 | /* |
74 | * Track whether we are within lttng-ust or application, for close | |
793d29c9 MD |
75 | * system call override by LD_PRELOAD library. This also tracks whether |
76 | * we are invoking close() from a signal handler nested on an | |
77 | * application thread. | |
6548fca4 | 78 | */ |
96a6162e | 79 | static DEFINE_URCU_TLS(int, ust_fd_mutex_nest); |
6548fca4 | 80 | |
3531136c MD |
81 | int lttng_ust_get_fd_mutex_nest(void); |
82 | ||
83 | int lttng_ust_get_fd_mutex_nest(void) | |
84 | { | |
85 | return ust_fd_mutex_nest; | |
86 | } | |
87 | ||
6548fca4 MD |
88 | /* fd_set used to book keep fd being used by lttng-ust. */ |
89 | static fd_set *lttng_fd_set; | |
90 | static int lttng_ust_max_fd; | |
91 | static int num_fd_sets; | |
7d34f27d | 92 | static int init_done; |
6548fca4 MD |
93 | |
94 | /* | |
95 | * Force a read (imply TLS fixup for dlopen) of TLS variables. | |
96 | */ | |
97 | void lttng_ust_fixup_fd_tracker_tls(void) | |
98 | { | |
96a6162e | 99 | asm volatile ("" : : "m" (URCU_TLS(ust_fd_mutex_nest))); |
6548fca4 MD |
100 | } |
101 | ||
102 | /* | |
103 | * Allocate the fd set array based on the hard limit set for this | |
104 | * process. This will be called during the constructor execution | |
105 | * and will also be called in the child after fork via lttng_ust_init. | |
106 | */ | |
107 | void lttng_ust_init_fd_tracker(void) | |
108 | { | |
109 | struct rlimit rlim; | |
110 | int i; | |
111 | ||
7d34f27d MD |
112 | if (CMM_LOAD_SHARED(init_done)) |
113 | return; | |
114 | ||
6548fca4 MD |
115 | memset(&rlim, 0, sizeof(rlim)); |
116 | /* Get the current possible max number of fd for this process. */ | |
117 | if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) | |
118 | abort(); | |
119 | /* | |
120 | * FD set array size determined using the hard limit. Even if | |
121 | * the process wishes to increase its limit using setrlimit, it | |
122 | * can only do so with the softlimit which will be less than the | |
123 | * hard limit. | |
124 | */ | |
125 | lttng_ust_max_fd = rlim.rlim_max; | |
126 | num_fd_sets = lttng_ust_max_fd / FD_SETSIZE; | |
127 | if (lttng_ust_max_fd % FD_SETSIZE) | |
128 | ++num_fd_sets; | |
129 | if (lttng_fd_set != NULL) { | |
130 | free(lttng_fd_set); | |
131 | lttng_fd_set = NULL; | |
132 | } | |
133 | lttng_fd_set = malloc(num_fd_sets * (sizeof(fd_set))); | |
134 | if (!lttng_fd_set) | |
135 | abort(); | |
136 | for (i = 0; i < num_fd_sets; i++) | |
137 | FD_ZERO((<tng_fd_set[i])); | |
7d34f27d | 138 | CMM_STORE_SHARED(init_done, 1); |
6548fca4 MD |
139 | } |
140 | ||
141 | void lttng_ust_lock_fd_tracker(void) | |
142 | { | |
96a6162e | 143 | sigset_t sig_all_blocked, orig_mask; |
595c1577 | 144 | int ret; |
283f4bec | 145 | |
595c1577 MD |
146 | if (lttng_ust_cancelstate_disable_push()) { |
147 | ERR("lttng_ust_cancelstate_disable_push"); | |
283f4bec | 148 | } |
96a6162e MD |
149 | sigfillset(&sig_all_blocked); |
150 | ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask); | |
151 | if (ret) { | |
152 | ERR("pthread_sigmask: %s", strerror(ret)); | |
153 | } | |
154 | if (!URCU_TLS(ust_fd_mutex_nest)++) { | |
155 | /* | |
156 | * Ensure the compiler don't move the store after the close() | |
157 | * call in case close() would be marked as leaf. | |
158 | */ | |
159 | cmm_barrier(); | |
160 | pthread_mutex_lock(&ust_safe_guard_fd_mutex); | |
96a6162e MD |
161 | } |
162 | ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL); | |
163 | if (ret) { | |
164 | ERR("pthread_sigmask: %s", strerror(ret)); | |
165 | } | |
6548fca4 MD |
166 | } |
167 | ||
168 | void lttng_ust_unlock_fd_tracker(void) | |
169 | { | |
96a6162e | 170 | sigset_t sig_all_blocked, orig_mask; |
595c1577 | 171 | int ret; |
283f4bec | 172 | |
96a6162e MD |
173 | sigfillset(&sig_all_blocked); |
174 | ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask); | |
175 | if (ret) { | |
176 | ERR("pthread_sigmask: %s", strerror(ret)); | |
177 | } | |
6548fca4 MD |
178 | /* |
179 | * Ensure the compiler don't move the store before the close() | |
180 | * call, in case close() would be marked as leaf. | |
181 | */ | |
182 | cmm_barrier(); | |
96a6162e | 183 | if (!--URCU_TLS(ust_fd_mutex_nest)) { |
96a6162e MD |
184 | pthread_mutex_unlock(&ust_safe_guard_fd_mutex); |
185 | } | |
186 | ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL); | |
283f4bec | 187 | if (ret) { |
96a6162e MD |
188 | ERR("pthread_sigmask: %s", strerror(ret)); |
189 | } | |
595c1577 MD |
190 | if (lttng_ust_cancelstate_disable_pop()) { |
191 | ERR("lttng_ust_cancelstate_disable_pop"); | |
283f4bec | 192 | } |
6548fca4 MD |
193 | } |
194 | ||
f5c453e9 JR |
195 | static int dup_std_fd(int fd) |
196 | { | |
5a4d96d1 | 197 | int ret, i; |
f5c453e9 JR |
198 | int fd_to_close[STDERR_FILENO + 1]; |
199 | int fd_to_close_count = 0; | |
200 | int dup_cmd = F_DUPFD; /* Default command */ | |
201 | int fd_valid = -1; | |
202 | ||
203 | if (!(IS_FD_STD(fd))) { | |
204 | /* Should not be here */ | |
205 | ret = -1; | |
206 | goto error; | |
207 | } | |
208 | ||
209 | /* Check for FD_CLOEXEC flag */ | |
210 | ret = fcntl(fd, F_GETFD); | |
211 | if (ret < 0) { | |
212 | PERROR("fcntl on f_getfd"); | |
213 | ret = -1; | |
214 | goto error; | |
215 | } | |
216 | ||
217 | if (ret & FD_CLOEXEC) { | |
218 | dup_cmd = F_DUPFD_CLOEXEC; | |
219 | } | |
220 | ||
221 | /* Perform dup */ | |
5a4d96d1 | 222 | for (i = 0; i < STDERR_FILENO + 1; i++) { |
f5c453e9 JR |
223 | ret = fcntl(fd, dup_cmd, 0); |
224 | if (ret < 0) { | |
225 | PERROR("fcntl dup fd"); | |
226 | goto error; | |
227 | } | |
228 | ||
229 | if (!(IS_FD_STD(ret))) { | |
230 | /* fd is outside of STD range, use it. */ | |
231 | fd_valid = ret; | |
232 | /* Close fd received as argument. */ | |
233 | fd_to_close[i] = fd; | |
234 | fd_to_close_count++; | |
235 | break; | |
236 | } | |
237 | ||
238 | fd_to_close[i] = ret; | |
239 | fd_to_close_count++; | |
240 | } | |
241 | ||
242 | /* Close intermediary fds */ | |
5a4d96d1 | 243 | for (i = 0; i < fd_to_close_count; i++) { |
f5c453e9 JR |
244 | ret = close(fd_to_close[i]); |
245 | if (ret) { | |
246 | PERROR("close on temporary fd: %d.", fd_to_close[i]); | |
247 | /* | |
248 | * Not using an abort here would yield a complicated | |
249 | * error handling for the caller. If a failure occurs | |
250 | * here, the system is already in a bad state. | |
251 | */ | |
252 | abort(); | |
253 | } | |
254 | } | |
255 | ||
256 | ret = fd_valid; | |
257 | error: | |
258 | return ret; | |
259 | } | |
260 | ||
6548fca4 MD |
261 | /* |
262 | * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd. | |
263 | * Has strict checking of fd validity. | |
f5c453e9 JR |
264 | * |
265 | * If fd <= 2, dup the fd until fd > 2. This enables us to bypass | |
266 | * problems that can be encountered if UST uses stdin, stdout, stderr | |
267 | * fds for internal use (daemon etc.). This can happen if the | |
268 | * application closes either of those file descriptors. Intermediary fds | |
269 | * are closed as needed. | |
270 | * | |
271 | * Return -1 on error. | |
272 | * | |
6548fca4 | 273 | */ |
f5c453e9 | 274 | int lttng_ust_add_fd_to_tracker(int fd) |
6548fca4 | 275 | { |
f5c453e9 | 276 | int ret; |
7d34f27d MD |
277 | /* |
278 | * Ensure the tracker is initialized when called from | |
279 | * constructors. | |
280 | */ | |
281 | lttng_ust_init_fd_tracker(); | |
96a6162e | 282 | assert(URCU_TLS(ust_fd_mutex_nest)); |
f5c453e9 JR |
283 | |
284 | if (IS_FD_STD(fd)) { | |
285 | ret = dup_std_fd(fd); | |
286 | if (ret < 0) { | |
287 | goto error; | |
288 | } | |
289 | fd = ret; | |
290 | } | |
291 | ||
6548fca4 MD |
292 | /* Trying to add an fd which we can not accommodate. */ |
293 | assert(IS_FD_VALID(fd)); | |
294 | /* Setting an fd thats already set. */ | |
295 | assert(!IS_FD_SET(fd, lttng_fd_set)); | |
296 | ||
297 | ADD_FD_TO_SET(fd, lttng_fd_set); | |
f5c453e9 JR |
298 | return fd; |
299 | error: | |
300 | return ret; | |
6548fca4 MD |
301 | } |
302 | ||
303 | /* | |
304 | * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd. | |
305 | * Has strict checking for fd validity. | |
306 | */ | |
307 | void lttng_ust_delete_fd_from_tracker(int fd) | |
308 | { | |
7d34f27d MD |
309 | /* |
310 | * Ensure the tracker is initialized when called from | |
311 | * constructors. | |
312 | */ | |
313 | lttng_ust_init_fd_tracker(); | |
314 | ||
96a6162e | 315 | assert(URCU_TLS(ust_fd_mutex_nest)); |
6548fca4 MD |
316 | /* Not a valid fd. */ |
317 | assert(IS_FD_VALID(fd)); | |
318 | /* Deleting an fd which was not set. */ | |
319 | assert(IS_FD_SET(fd, lttng_fd_set)); | |
320 | ||
321 | DEL_FD_FROM_SET(fd, lttng_fd_set); | |
322 | } | |
323 | ||
324 | /* | |
325 | * Interface allowing applications to close arbitrary file descriptors. | |
326 | * We check if it is owned by lttng-ust, and return -1, errno=EBADF | |
327 | * instead of closing it if it is the case. | |
328 | */ | |
329 | int lttng_ust_safe_close_fd(int fd, int (*close_cb)(int fd)) | |
330 | { | |
331 | int ret = 0; | |
332 | ||
333 | lttng_ust_fixup_fd_tracker_tls(); | |
334 | ||
7d34f27d MD |
335 | /* |
336 | * Ensure the tracker is initialized when called from | |
337 | * constructors. | |
338 | */ | |
339 | lttng_ust_init_fd_tracker(); | |
340 | ||
6548fca4 MD |
341 | /* |
342 | * If called from lttng-ust, we directly call close without | |
343 | * validating whether the FD is part of the tracked set. | |
344 | */ | |
793d29c9 | 345 | if (URCU_TLS(ust_fd_mutex_nest)) |
6548fca4 MD |
346 | return close_cb(fd); |
347 | ||
348 | lttng_ust_lock_fd_tracker(); | |
349 | if (IS_FD_VALID(fd) && IS_FD_SET(fd, lttng_fd_set)) { | |
350 | ret = -1; | |
351 | errno = EBADF; | |
352 | } else { | |
353 | ret = close_cb(fd); | |
354 | } | |
355 | lttng_ust_unlock_fd_tracker(); | |
356 | ||
357 | return ret; | |
358 | } | |
359 | ||
52a20dc7 MD |
360 | /* |
361 | * Interface allowing applications to close arbitrary streams. | |
362 | * We check if it is owned by lttng-ust, and return -1, errno=EBADF | |
363 | * instead of closing it if it is the case. | |
364 | */ | |
365 | int lttng_ust_safe_fclose_stream(FILE *stream, int (*fclose_cb)(FILE *stream)) | |
366 | { | |
367 | int ret = 0, fd; | |
368 | ||
369 | lttng_ust_fixup_fd_tracker_tls(); | |
370 | ||
7d34f27d MD |
371 | /* |
372 | * Ensure the tracker is initialized when called from | |
373 | * constructors. | |
374 | */ | |
375 | lttng_ust_init_fd_tracker(); | |
376 | ||
52a20dc7 MD |
377 | /* |
378 | * If called from lttng-ust, we directly call fclose without | |
379 | * validating whether the FD is part of the tracked set. | |
380 | */ | |
793d29c9 | 381 | if (URCU_TLS(ust_fd_mutex_nest)) |
52a20dc7 MD |
382 | return fclose_cb(stream); |
383 | ||
384 | fd = fileno(stream); | |
385 | ||
386 | lttng_ust_lock_fd_tracker(); | |
387 | if (IS_FD_VALID(fd) && IS_FD_SET(fd, lttng_fd_set)) { | |
388 | ret = -1; | |
389 | errno = EBADF; | |
390 | } else { | |
391 | ret = fclose_cb(stream); | |
392 | } | |
393 | lttng_ust_unlock_fd_tracker(); | |
394 | ||
395 | return ret; | |
396 | } | |
397 | ||
6548fca4 MD |
398 | #ifdef __OpenBSD__ |
399 | static void set_close_success(int *p) | |
400 | { | |
401 | *p = 1; | |
402 | } | |
403 | static int test_close_success(const int *p) | |
404 | { | |
405 | return *p; | |
406 | } | |
407 | #else | |
408 | static void set_close_success(int *p __attribute__((unused))) | |
409 | { | |
410 | } | |
411 | static int test_close_success(const int *p __attribute__((unused))) | |
412 | { | |
413 | return 1; | |
414 | } | |
415 | #endif | |
416 | ||
417 | /* | |
418 | * Implement helper for closefrom() override. | |
419 | */ | |
420 | int lttng_ust_safe_closefrom_fd(int lowfd, int (*close_cb)(int fd)) | |
421 | { | |
422 | int ret = 0, close_success = 0, i; | |
423 | ||
424 | lttng_ust_fixup_fd_tracker_tls(); | |
425 | ||
7d34f27d MD |
426 | /* |
427 | * Ensure the tracker is initialized when called from | |
428 | * constructors. | |
429 | */ | |
430 | lttng_ust_init_fd_tracker(); | |
431 | ||
6548fca4 MD |
432 | if (lowfd < 0) { |
433 | /* | |
434 | * NetBSD return EBADF if fd is invalid. | |
435 | */ | |
436 | errno = EBADF; | |
437 | ret = -1; | |
438 | goto end; | |
439 | } | |
440 | /* | |
441 | * If called from lttng-ust, we directly call close without | |
442 | * validating whether the FD is part of the tracked set. | |
443 | */ | |
793d29c9 | 444 | if (URCU_TLS(ust_fd_mutex_nest)) { |
6548fca4 MD |
445 | for (i = lowfd; i < lttng_ust_max_fd; i++) { |
446 | if (close_cb(i) < 0) { | |
447 | switch (errno) { | |
448 | case EBADF: | |
449 | continue; | |
450 | case EINTR: | |
451 | default: | |
452 | ret = -1; | |
453 | goto end; | |
454 | } | |
455 | } | |
456 | set_close_success(&close_success); | |
457 | } | |
458 | } else { | |
459 | lttng_ust_lock_fd_tracker(); | |
460 | for (i = lowfd; i < lttng_ust_max_fd; i++) { | |
461 | if (IS_FD_VALID(i) && IS_FD_SET(i, lttng_fd_set)) | |
462 | continue; | |
463 | if (close_cb(i) < 0) { | |
464 | switch (errno) { | |
465 | case EBADF: | |
466 | continue; | |
467 | case EINTR: | |
468 | default: | |
469 | ret = -1; | |
470 | lttng_ust_unlock_fd_tracker(); | |
471 | goto end; | |
472 | } | |
473 | } | |
474 | set_close_success(&close_success); | |
475 | } | |
476 | lttng_ust_unlock_fd_tracker(); | |
477 | } | |
478 | if (!test_close_success(&close_success)) { | |
479 | /* | |
480 | * OpenBSD return EBADF if fd is greater than all open | |
481 | * file descriptors. | |
482 | */ | |
483 | ret = -1; | |
484 | errno = EBADF; | |
485 | } | |
486 | end: | |
487 | return ret; | |
488 | } |