Commit | Line | Data |
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6548fca4 | 1 | /* |
c0c0989a | 2 | * SPDX-License-Identifier: LGPL-2.1-only |
6548fca4 | 3 | * |
c0c0989a MJ |
4 | * Copyright (C) 2016 Aravind HT <aravind.ht@gmail.com> |
5 | * Copyright (C) 2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
6548fca4 MD |
6 | */ |
7 | ||
6548fca4 MD |
8 | #include <limits.h> |
9 | #include <stdio.h> | |
10 | #include <stdlib.h> | |
11 | #include <string.h> | |
12 | #include <sys/types.h> | |
13 | #include <unistd.h> | |
14 | #include <assert.h> | |
15 | #include <errno.h> | |
16 | #include <fcntl.h> | |
17 | #include <sys/select.h> | |
18 | #include <sys/resource.h> | |
19 | #include <sys/time.h> | |
20 | #include <fcntl.h> | |
21 | #include <pthread.h> | |
96a6162e MD |
22 | #include <signal.h> |
23 | #include <stdbool.h> | |
6548fca4 MD |
24 | #include <urcu/compiler.h> |
25 | #include <urcu/tls-compat.h> | |
7d34f27d | 26 | #include <urcu/system.h> |
6548fca4 | 27 | |
9d315d6d MJ |
28 | #include "common/ust-fd.h" |
29 | #include "common/macros.h" | |
6548fca4 | 30 | #include <lttng/ust-error.h> |
9d315d6d | 31 | #include "common/logging.h" |
6548fca4 | 32 | |
6548fca4 MD |
33 | /* Operations on the fd set. */ |
34 | #define IS_FD_VALID(fd) ((fd) >= 0 && (fd) < lttng_ust_max_fd) | |
35 | #define GET_FD_SET_FOR_FD(fd, fd_sets) (&((fd_sets)[(fd) / FD_SETSIZE])) | |
36 | #define CALC_INDEX_TO_SET(fd) ((fd) % FD_SETSIZE) | |
f5c453e9 | 37 | #define IS_FD_STD(fd) (IS_FD_VALID(fd) && (fd) <= STDERR_FILENO) |
6548fca4 MD |
38 | |
39 | /* Check fd validity before calling these. */ | |
40 | #define ADD_FD_TO_SET(fd, fd_sets) \ | |
41 | FD_SET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
42 | #define IS_FD_SET(fd, fd_sets) \ | |
43 | FD_ISSET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
44 | #define DEL_FD_FROM_SET(fd, fd_sets) \ | |
45 | FD_CLR(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
46 | ||
47 | /* | |
48 | * Protect the lttng_fd_set. Nests within the ust_lock, and therefore | |
49 | * within the libc dl lock. Therefore, we need to fixup the TLS before | |
50 | * nesting into this lock. | |
c1be081a MD |
51 | * |
52 | * The ust_safe_guard_fd_mutex nests within the ust_mutex. This mutex | |
53 | * is also held across fork. | |
6548fca4 MD |
54 | */ |
55 | static pthread_mutex_t ust_safe_guard_fd_mutex = PTHREAD_MUTEX_INITIALIZER; | |
283f4bec MD |
56 | |
57 | /* | |
58 | * Cancel state when grabbing the ust_safe_guard_fd_mutex. Saved when | |
59 | * locking, restored on unlock. Protected by ust_safe_guard_fd_mutex. | |
60 | */ | |
61 | static int ust_safe_guard_saved_cancelstate; | |
62 | ||
6548fca4 MD |
63 | /* |
64 | * Track whether we are within lttng-ust or application, for close | |
793d29c9 MD |
65 | * system call override by LD_PRELOAD library. This also tracks whether |
66 | * we are invoking close() from a signal handler nested on an | |
67 | * application thread. | |
6548fca4 | 68 | */ |
96a6162e | 69 | static DEFINE_URCU_TLS(int, ust_fd_mutex_nest); |
6548fca4 MD |
70 | |
71 | /* fd_set used to book keep fd being used by lttng-ust. */ | |
72 | static fd_set *lttng_fd_set; | |
73 | static int lttng_ust_max_fd; | |
74 | static int num_fd_sets; | |
7d34f27d | 75 | static int init_done; |
6548fca4 MD |
76 | |
77 | /* | |
78 | * Force a read (imply TLS fixup for dlopen) of TLS variables. | |
79 | */ | |
80 | void lttng_ust_fixup_fd_tracker_tls(void) | |
81 | { | |
96a6162e | 82 | asm volatile ("" : : "m" (URCU_TLS(ust_fd_mutex_nest))); |
6548fca4 MD |
83 | } |
84 | ||
85 | /* | |
86 | * Allocate the fd set array based on the hard limit set for this | |
87 | * process. This will be called during the constructor execution | |
88 | * and will also be called in the child after fork via lttng_ust_init. | |
89 | */ | |
90 | void lttng_ust_init_fd_tracker(void) | |
91 | { | |
92 | struct rlimit rlim; | |
93 | int i; | |
94 | ||
7d34f27d MD |
95 | if (CMM_LOAD_SHARED(init_done)) |
96 | return; | |
97 | ||
6548fca4 MD |
98 | memset(&rlim, 0, sizeof(rlim)); |
99 | /* Get the current possible max number of fd for this process. */ | |
100 | if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) | |
101 | abort(); | |
102 | /* | |
103 | * FD set array size determined using the hard limit. Even if | |
104 | * the process wishes to increase its limit using setrlimit, it | |
105 | * can only do so with the softlimit which will be less than the | |
106 | * hard limit. | |
107 | */ | |
108 | lttng_ust_max_fd = rlim.rlim_max; | |
109 | num_fd_sets = lttng_ust_max_fd / FD_SETSIZE; | |
110 | if (lttng_ust_max_fd % FD_SETSIZE) | |
111 | ++num_fd_sets; | |
112 | if (lttng_fd_set != NULL) { | |
113 | free(lttng_fd_set); | |
114 | lttng_fd_set = NULL; | |
115 | } | |
116 | lttng_fd_set = malloc(num_fd_sets * (sizeof(fd_set))); | |
117 | if (!lttng_fd_set) | |
118 | abort(); | |
119 | for (i = 0; i < num_fd_sets; i++) | |
120 | FD_ZERO((<tng_fd_set[i])); | |
7d34f27d | 121 | CMM_STORE_SHARED(init_done, 1); |
6548fca4 MD |
122 | } |
123 | ||
124 | void lttng_ust_lock_fd_tracker(void) | |
125 | { | |
96a6162e | 126 | sigset_t sig_all_blocked, orig_mask; |
283f4bec MD |
127 | int ret, oldstate; |
128 | ||
129 | ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate); | |
130 | if (ret) { | |
131 | ERR("pthread_setcancelstate: %s", strerror(ret)); | |
132 | } | |
96a6162e MD |
133 | sigfillset(&sig_all_blocked); |
134 | ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask); | |
135 | if (ret) { | |
136 | ERR("pthread_sigmask: %s", strerror(ret)); | |
137 | } | |
138 | if (!URCU_TLS(ust_fd_mutex_nest)++) { | |
139 | /* | |
140 | * Ensure the compiler don't move the store after the close() | |
141 | * call in case close() would be marked as leaf. | |
142 | */ | |
143 | cmm_barrier(); | |
144 | pthread_mutex_lock(&ust_safe_guard_fd_mutex); | |
145 | ust_safe_guard_saved_cancelstate = oldstate; | |
146 | } | |
147 | ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL); | |
148 | if (ret) { | |
149 | ERR("pthread_sigmask: %s", strerror(ret)); | |
150 | } | |
6548fca4 MD |
151 | } |
152 | ||
153 | void lttng_ust_unlock_fd_tracker(void) | |
154 | { | |
96a6162e | 155 | sigset_t sig_all_blocked, orig_mask; |
283f4bec | 156 | int ret, newstate, oldstate; |
96a6162e | 157 | bool restore_cancel = false; |
283f4bec | 158 | |
96a6162e MD |
159 | sigfillset(&sig_all_blocked); |
160 | ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask); | |
161 | if (ret) { | |
162 | ERR("pthread_sigmask: %s", strerror(ret)); | |
163 | } | |
6548fca4 MD |
164 | /* |
165 | * Ensure the compiler don't move the store before the close() | |
166 | * call, in case close() would be marked as leaf. | |
167 | */ | |
168 | cmm_barrier(); | |
96a6162e MD |
169 | if (!--URCU_TLS(ust_fd_mutex_nest)) { |
170 | newstate = ust_safe_guard_saved_cancelstate; | |
171 | restore_cancel = true; | |
172 | pthread_mutex_unlock(&ust_safe_guard_fd_mutex); | |
173 | } | |
174 | ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL); | |
283f4bec | 175 | if (ret) { |
96a6162e MD |
176 | ERR("pthread_sigmask: %s", strerror(ret)); |
177 | } | |
178 | if (restore_cancel) { | |
179 | ret = pthread_setcancelstate(newstate, &oldstate); | |
180 | if (ret) { | |
181 | ERR("pthread_setcancelstate: %s", strerror(ret)); | |
182 | } | |
283f4bec | 183 | } |
6548fca4 MD |
184 | } |
185 | ||
f5c453e9 JR |
186 | static int dup_std_fd(int fd) |
187 | { | |
5a4d96d1 | 188 | int ret, i; |
f5c453e9 JR |
189 | int fd_to_close[STDERR_FILENO + 1]; |
190 | int fd_to_close_count = 0; | |
191 | int dup_cmd = F_DUPFD; /* Default command */ | |
192 | int fd_valid = -1; | |
193 | ||
194 | if (!(IS_FD_STD(fd))) { | |
195 | /* Should not be here */ | |
196 | ret = -1; | |
197 | goto error; | |
198 | } | |
199 | ||
200 | /* Check for FD_CLOEXEC flag */ | |
201 | ret = fcntl(fd, F_GETFD); | |
202 | if (ret < 0) { | |
203 | PERROR("fcntl on f_getfd"); | |
204 | ret = -1; | |
205 | goto error; | |
206 | } | |
207 | ||
208 | if (ret & FD_CLOEXEC) { | |
209 | dup_cmd = F_DUPFD_CLOEXEC; | |
210 | } | |
211 | ||
212 | /* Perform dup */ | |
5a4d96d1 | 213 | for (i = 0; i < STDERR_FILENO + 1; i++) { |
f5c453e9 JR |
214 | ret = fcntl(fd, dup_cmd, 0); |
215 | if (ret < 0) { | |
216 | PERROR("fcntl dup fd"); | |
217 | goto error; | |
218 | } | |
219 | ||
220 | if (!(IS_FD_STD(ret))) { | |
221 | /* fd is outside of STD range, use it. */ | |
222 | fd_valid = ret; | |
223 | /* Close fd received as argument. */ | |
224 | fd_to_close[i] = fd; | |
225 | fd_to_close_count++; | |
226 | break; | |
227 | } | |
228 | ||
229 | fd_to_close[i] = ret; | |
230 | fd_to_close_count++; | |
231 | } | |
232 | ||
233 | /* Close intermediary fds */ | |
5a4d96d1 | 234 | for (i = 0; i < fd_to_close_count; i++) { |
f5c453e9 JR |
235 | ret = close(fd_to_close[i]); |
236 | if (ret) { | |
237 | PERROR("close on temporary fd: %d.", fd_to_close[i]); | |
238 | /* | |
239 | * Not using an abort here would yield a complicated | |
240 | * error handling for the caller. If a failure occurs | |
241 | * here, the system is already in a bad state. | |
242 | */ | |
243 | abort(); | |
244 | } | |
245 | } | |
246 | ||
247 | ret = fd_valid; | |
248 | error: | |
249 | return ret; | |
250 | } | |
251 | ||
6548fca4 MD |
252 | /* |
253 | * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd. | |
254 | * Has strict checking of fd validity. | |
f5c453e9 JR |
255 | * |
256 | * If fd <= 2, dup the fd until fd > 2. This enables us to bypass | |
257 | * problems that can be encountered if UST uses stdin, stdout, stderr | |
258 | * fds for internal use (daemon etc.). This can happen if the | |
259 | * application closes either of those file descriptors. Intermediary fds | |
260 | * are closed as needed. | |
261 | * | |
262 | * Return -1 on error. | |
263 | * | |
6548fca4 | 264 | */ |
f5c453e9 | 265 | int lttng_ust_add_fd_to_tracker(int fd) |
6548fca4 | 266 | { |
f5c453e9 | 267 | int ret; |
7d34f27d MD |
268 | /* |
269 | * Ensure the tracker is initialized when called from | |
270 | * constructors. | |
271 | */ | |
272 | lttng_ust_init_fd_tracker(); | |
96a6162e | 273 | assert(URCU_TLS(ust_fd_mutex_nest)); |
f5c453e9 JR |
274 | |
275 | if (IS_FD_STD(fd)) { | |
276 | ret = dup_std_fd(fd); | |
277 | if (ret < 0) { | |
278 | goto error; | |
279 | } | |
280 | fd = ret; | |
281 | } | |
282 | ||
6548fca4 MD |
283 | /* Trying to add an fd which we can not accommodate. */ |
284 | assert(IS_FD_VALID(fd)); | |
285 | /* Setting an fd thats already set. */ | |
286 | assert(!IS_FD_SET(fd, lttng_fd_set)); | |
287 | ||
288 | ADD_FD_TO_SET(fd, lttng_fd_set); | |
f5c453e9 JR |
289 | return fd; |
290 | error: | |
291 | return ret; | |
6548fca4 MD |
292 | } |
293 | ||
294 | /* | |
295 | * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd. | |
296 | * Has strict checking for fd validity. | |
297 | */ | |
298 | void lttng_ust_delete_fd_from_tracker(int fd) | |
299 | { | |
7d34f27d MD |
300 | /* |
301 | * Ensure the tracker is initialized when called from | |
302 | * constructors. | |
303 | */ | |
304 | lttng_ust_init_fd_tracker(); | |
305 | ||
96a6162e | 306 | assert(URCU_TLS(ust_fd_mutex_nest)); |
6548fca4 MD |
307 | /* Not a valid fd. */ |
308 | assert(IS_FD_VALID(fd)); | |
309 | /* Deleting an fd which was not set. */ | |
310 | assert(IS_FD_SET(fd, lttng_fd_set)); | |
311 | ||
312 | DEL_FD_FROM_SET(fd, lttng_fd_set); | |
313 | } | |
314 | ||
315 | /* | |
316 | * Interface allowing applications to close arbitrary file descriptors. | |
317 | * We check if it is owned by lttng-ust, and return -1, errno=EBADF | |
318 | * instead of closing it if it is the case. | |
319 | */ | |
320 | int lttng_ust_safe_close_fd(int fd, int (*close_cb)(int fd)) | |
321 | { | |
322 | int ret = 0; | |
323 | ||
324 | lttng_ust_fixup_fd_tracker_tls(); | |
325 | ||
7d34f27d MD |
326 | /* |
327 | * Ensure the tracker is initialized when called from | |
328 | * constructors. | |
329 | */ | |
330 | lttng_ust_init_fd_tracker(); | |
331 | ||
6548fca4 MD |
332 | /* |
333 | * If called from lttng-ust, we directly call close without | |
334 | * validating whether the FD is part of the tracked set. | |
335 | */ | |
793d29c9 | 336 | if (URCU_TLS(ust_fd_mutex_nest)) |
6548fca4 MD |
337 | return close_cb(fd); |
338 | ||
339 | lttng_ust_lock_fd_tracker(); | |
340 | if (IS_FD_VALID(fd) && IS_FD_SET(fd, lttng_fd_set)) { | |
341 | ret = -1; | |
342 | errno = EBADF; | |
343 | } else { | |
344 | ret = close_cb(fd); | |
345 | } | |
346 | lttng_ust_unlock_fd_tracker(); | |
347 | ||
348 | return ret; | |
349 | } | |
350 | ||
52a20dc7 MD |
351 | /* |
352 | * Interface allowing applications to close arbitrary streams. | |
353 | * We check if it is owned by lttng-ust, and return -1, errno=EBADF | |
354 | * instead of closing it if it is the case. | |
355 | */ | |
356 | int lttng_ust_safe_fclose_stream(FILE *stream, int (*fclose_cb)(FILE *stream)) | |
357 | { | |
358 | int ret = 0, fd; | |
359 | ||
360 | lttng_ust_fixup_fd_tracker_tls(); | |
361 | ||
7d34f27d MD |
362 | /* |
363 | * Ensure the tracker is initialized when called from | |
364 | * constructors. | |
365 | */ | |
366 | lttng_ust_init_fd_tracker(); | |
367 | ||
52a20dc7 MD |
368 | /* |
369 | * If called from lttng-ust, we directly call fclose without | |
370 | * validating whether the FD is part of the tracked set. | |
371 | */ | |
793d29c9 | 372 | if (URCU_TLS(ust_fd_mutex_nest)) |
52a20dc7 MD |
373 | return fclose_cb(stream); |
374 | ||
375 | fd = fileno(stream); | |
376 | ||
377 | lttng_ust_lock_fd_tracker(); | |
378 | if (IS_FD_VALID(fd) && IS_FD_SET(fd, lttng_fd_set)) { | |
379 | ret = -1; | |
380 | errno = EBADF; | |
381 | } else { | |
382 | ret = fclose_cb(stream); | |
383 | } | |
384 | lttng_ust_unlock_fd_tracker(); | |
385 | ||
386 | return ret; | |
387 | } | |
388 | ||
6548fca4 MD |
389 | #ifdef __OpenBSD__ |
390 | static void set_close_success(int *p) | |
391 | { | |
392 | *p = 1; | |
393 | } | |
394 | static int test_close_success(const int *p) | |
395 | { | |
396 | return *p; | |
397 | } | |
398 | #else | |
399 | static void set_close_success(int *p __attribute__((unused))) | |
400 | { | |
401 | } | |
402 | static int test_close_success(const int *p __attribute__((unused))) | |
403 | { | |
404 | return 1; | |
405 | } | |
406 | #endif | |
407 | ||
408 | /* | |
409 | * Implement helper for closefrom() override. | |
410 | */ | |
411 | int lttng_ust_safe_closefrom_fd(int lowfd, int (*close_cb)(int fd)) | |
412 | { | |
413 | int ret = 0, close_success = 0, i; | |
414 | ||
415 | lttng_ust_fixup_fd_tracker_tls(); | |
416 | ||
7d34f27d MD |
417 | /* |
418 | * Ensure the tracker is initialized when called from | |
419 | * constructors. | |
420 | */ | |
421 | lttng_ust_init_fd_tracker(); | |
422 | ||
6548fca4 MD |
423 | if (lowfd < 0) { |
424 | /* | |
425 | * NetBSD return EBADF if fd is invalid. | |
426 | */ | |
427 | errno = EBADF; | |
428 | ret = -1; | |
429 | goto end; | |
430 | } | |
431 | /* | |
432 | * If called from lttng-ust, we directly call close without | |
433 | * validating whether the FD is part of the tracked set. | |
434 | */ | |
793d29c9 | 435 | if (URCU_TLS(ust_fd_mutex_nest)) { |
6548fca4 MD |
436 | for (i = lowfd; i < lttng_ust_max_fd; i++) { |
437 | if (close_cb(i) < 0) { | |
438 | switch (errno) { | |
439 | case EBADF: | |
440 | continue; | |
441 | case EINTR: | |
442 | default: | |
443 | ret = -1; | |
444 | goto end; | |
445 | } | |
446 | } | |
447 | set_close_success(&close_success); | |
448 | } | |
449 | } else { | |
450 | lttng_ust_lock_fd_tracker(); | |
451 | for (i = lowfd; i < lttng_ust_max_fd; i++) { | |
452 | if (IS_FD_VALID(i) && IS_FD_SET(i, lttng_fd_set)) | |
453 | continue; | |
454 | if (close_cb(i) < 0) { | |
455 | switch (errno) { | |
456 | case EBADF: | |
457 | continue; | |
458 | case EINTR: | |
459 | default: | |
460 | ret = -1; | |
461 | lttng_ust_unlock_fd_tracker(); | |
462 | goto end; | |
463 | } | |
464 | } | |
465 | set_close_success(&close_success); | |
466 | } | |
467 | lttng_ust_unlock_fd_tracker(); | |
468 | } | |
469 | if (!test_close_success(&close_success)) { | |
470 | /* | |
471 | * OpenBSD return EBADF if fd is greater than all open | |
472 | * file descriptors. | |
473 | */ | |
474 | ret = -1; | |
475 | errno = EBADF; | |
476 | } | |
477 | end: | |
478 | return ret; | |
479 | } |