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 | |
fca97dfd MJ |
33 | #include "lib/lttng-ust-common/fd-tracker.h" |
34 | ||
6548fca4 MD |
35 | /* Operations on the fd set. */ |
36 | #define IS_FD_VALID(fd) ((fd) >= 0 && (fd) < lttng_ust_max_fd) | |
37 | #define GET_FD_SET_FOR_FD(fd, fd_sets) (&((fd_sets)[(fd) / FD_SETSIZE])) | |
38 | #define CALC_INDEX_TO_SET(fd) ((fd) % FD_SETSIZE) | |
f5c453e9 | 39 | #define IS_FD_STD(fd) (IS_FD_VALID(fd) && (fd) <= STDERR_FILENO) |
6548fca4 MD |
40 | |
41 | /* Check fd validity before calling these. */ | |
42 | #define ADD_FD_TO_SET(fd, fd_sets) \ | |
43 | FD_SET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
44 | #define IS_FD_SET(fd, fd_sets) \ | |
45 | FD_ISSET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
46 | #define DEL_FD_FROM_SET(fd, fd_sets) \ | |
47 | FD_CLR(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
48 | ||
49 | /* | |
50 | * Protect the lttng_fd_set. Nests within the ust_lock, and therefore | |
a9fd951a | 51 | * within the libc dl lock. Therefore, we need to allocate the TLS before |
6548fca4 | 52 | * nesting into this lock. |
c1be081a MD |
53 | * |
54 | * The ust_safe_guard_fd_mutex nests within the ust_mutex. This mutex | |
55 | * is also held across fork. | |
6548fca4 MD |
56 | */ |
57 | static pthread_mutex_t ust_safe_guard_fd_mutex = PTHREAD_MUTEX_INITIALIZER; | |
283f4bec MD |
58 | |
59 | /* | |
60 | * Cancel state when grabbing the ust_safe_guard_fd_mutex. Saved when | |
61 | * locking, restored on unlock. Protected by ust_safe_guard_fd_mutex. | |
62 | */ | |
63 | static int ust_safe_guard_saved_cancelstate; | |
64 | ||
6548fca4 MD |
65 | /* |
66 | * Track whether we are within lttng-ust or application, for close | |
793d29c9 MD |
67 | * system call override by LD_PRELOAD library. This also tracks whether |
68 | * we are invoking close() from a signal handler nested on an | |
69 | * application thread. | |
6548fca4 | 70 | */ |
96a6162e | 71 | static DEFINE_URCU_TLS(int, ust_fd_mutex_nest); |
6548fca4 MD |
72 | |
73 | /* fd_set used to book keep fd being used by lttng-ust. */ | |
74 | static fd_set *lttng_fd_set; | |
75 | static int lttng_ust_max_fd; | |
76 | static int num_fd_sets; | |
7d34f27d | 77 | static int init_done; |
6548fca4 MD |
78 | |
79 | /* | |
a9fd951a | 80 | * Force a read (imply TLS allocation for dlopen) of TLS variables. |
6548fca4 | 81 | */ |
a9fd951a | 82 | void lttng_ust_fd_tracker_alloc_tls(void) |
6548fca4 | 83 | { |
96a6162e | 84 | asm volatile ("" : : "m" (URCU_TLS(ust_fd_mutex_nest))); |
6548fca4 MD |
85 | } |
86 | ||
87 | /* | |
88 | * Allocate the fd set array based on the hard limit set for this | |
89 | * process. This will be called during the constructor execution | |
90 | * and will also be called in the child after fork via lttng_ust_init. | |
91 | */ | |
fca97dfd | 92 | void lttng_ust_fd_tracker_init(void) |
6548fca4 MD |
93 | { |
94 | struct rlimit rlim; | |
95 | int i; | |
96 | ||
7d34f27d MD |
97 | if (CMM_LOAD_SHARED(init_done)) |
98 | return; | |
99 | ||
6548fca4 MD |
100 | memset(&rlim, 0, sizeof(rlim)); |
101 | /* Get the current possible max number of fd for this process. */ | |
102 | if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) | |
103 | abort(); | |
104 | /* | |
105 | * FD set array size determined using the hard limit. Even if | |
106 | * the process wishes to increase its limit using setrlimit, it | |
107 | * can only do so with the softlimit which will be less than the | |
108 | * hard limit. | |
109 | */ | |
110 | lttng_ust_max_fd = rlim.rlim_max; | |
111 | num_fd_sets = lttng_ust_max_fd / FD_SETSIZE; | |
112 | if (lttng_ust_max_fd % FD_SETSIZE) | |
113 | ++num_fd_sets; | |
114 | if (lttng_fd_set != NULL) { | |
115 | free(lttng_fd_set); | |
116 | lttng_fd_set = NULL; | |
117 | } | |
118 | lttng_fd_set = malloc(num_fd_sets * (sizeof(fd_set))); | |
119 | if (!lttng_fd_set) | |
120 | abort(); | |
121 | for (i = 0; i < num_fd_sets; i++) | |
122 | FD_ZERO((<tng_fd_set[i])); | |
7d34f27d | 123 | CMM_STORE_SHARED(init_done, 1); |
6548fca4 MD |
124 | } |
125 | ||
126 | void lttng_ust_lock_fd_tracker(void) | |
127 | { | |
96a6162e | 128 | sigset_t sig_all_blocked, orig_mask; |
283f4bec MD |
129 | int ret, oldstate; |
130 | ||
131 | ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate); | |
132 | if (ret) { | |
133 | ERR("pthread_setcancelstate: %s", strerror(ret)); | |
134 | } | |
96a6162e MD |
135 | sigfillset(&sig_all_blocked); |
136 | ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask); | |
137 | if (ret) { | |
138 | ERR("pthread_sigmask: %s", strerror(ret)); | |
139 | } | |
140 | if (!URCU_TLS(ust_fd_mutex_nest)++) { | |
141 | /* | |
142 | * Ensure the compiler don't move the store after the close() | |
143 | * call in case close() would be marked as leaf. | |
144 | */ | |
145 | cmm_barrier(); | |
146 | pthread_mutex_lock(&ust_safe_guard_fd_mutex); | |
147 | ust_safe_guard_saved_cancelstate = oldstate; | |
148 | } | |
149 | ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL); | |
150 | if (ret) { | |
151 | ERR("pthread_sigmask: %s", strerror(ret)); | |
152 | } | |
6548fca4 MD |
153 | } |
154 | ||
155 | void lttng_ust_unlock_fd_tracker(void) | |
156 | { | |
96a6162e | 157 | sigset_t sig_all_blocked, orig_mask; |
283f4bec | 158 | int ret, newstate, oldstate; |
96a6162e | 159 | bool restore_cancel = false; |
283f4bec | 160 | |
96a6162e MD |
161 | sigfillset(&sig_all_blocked); |
162 | ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask); | |
163 | if (ret) { | |
164 | ERR("pthread_sigmask: %s", strerror(ret)); | |
165 | } | |
6548fca4 MD |
166 | /* |
167 | * Ensure the compiler don't move the store before the close() | |
168 | * call, in case close() would be marked as leaf. | |
169 | */ | |
170 | cmm_barrier(); | |
96a6162e MD |
171 | if (!--URCU_TLS(ust_fd_mutex_nest)) { |
172 | newstate = ust_safe_guard_saved_cancelstate; | |
173 | restore_cancel = true; | |
174 | pthread_mutex_unlock(&ust_safe_guard_fd_mutex); | |
175 | } | |
176 | ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL); | |
283f4bec | 177 | if (ret) { |
96a6162e MD |
178 | ERR("pthread_sigmask: %s", strerror(ret)); |
179 | } | |
180 | if (restore_cancel) { | |
181 | ret = pthread_setcancelstate(newstate, &oldstate); | |
182 | if (ret) { | |
183 | ERR("pthread_setcancelstate: %s", strerror(ret)); | |
184 | } | |
283f4bec | 185 | } |
6548fca4 MD |
186 | } |
187 | ||
f5c453e9 JR |
188 | static int dup_std_fd(int fd) |
189 | { | |
5a4d96d1 | 190 | int ret, i; |
f5c453e9 JR |
191 | int fd_to_close[STDERR_FILENO + 1]; |
192 | int fd_to_close_count = 0; | |
193 | int dup_cmd = F_DUPFD; /* Default command */ | |
194 | int fd_valid = -1; | |
195 | ||
196 | if (!(IS_FD_STD(fd))) { | |
197 | /* Should not be here */ | |
198 | ret = -1; | |
199 | goto error; | |
200 | } | |
201 | ||
202 | /* Check for FD_CLOEXEC flag */ | |
203 | ret = fcntl(fd, F_GETFD); | |
204 | if (ret < 0) { | |
205 | PERROR("fcntl on f_getfd"); | |
206 | ret = -1; | |
207 | goto error; | |
208 | } | |
209 | ||
210 | if (ret & FD_CLOEXEC) { | |
211 | dup_cmd = F_DUPFD_CLOEXEC; | |
212 | } | |
213 | ||
214 | /* Perform dup */ | |
5a4d96d1 | 215 | for (i = 0; i < STDERR_FILENO + 1; i++) { |
f5c453e9 JR |
216 | ret = fcntl(fd, dup_cmd, 0); |
217 | if (ret < 0) { | |
218 | PERROR("fcntl dup fd"); | |
219 | goto error; | |
220 | } | |
221 | ||
222 | if (!(IS_FD_STD(ret))) { | |
223 | /* fd is outside of STD range, use it. */ | |
224 | fd_valid = ret; | |
225 | /* Close fd received as argument. */ | |
226 | fd_to_close[i] = fd; | |
227 | fd_to_close_count++; | |
228 | break; | |
229 | } | |
230 | ||
231 | fd_to_close[i] = ret; | |
232 | fd_to_close_count++; | |
233 | } | |
234 | ||
235 | /* Close intermediary fds */ | |
5a4d96d1 | 236 | for (i = 0; i < fd_to_close_count; i++) { |
f5c453e9 JR |
237 | ret = close(fd_to_close[i]); |
238 | if (ret) { | |
239 | PERROR("close on temporary fd: %d.", fd_to_close[i]); | |
240 | /* | |
241 | * Not using an abort here would yield a complicated | |
242 | * error handling for the caller. If a failure occurs | |
243 | * here, the system is already in a bad state. | |
244 | */ | |
245 | abort(); | |
246 | } | |
247 | } | |
248 | ||
249 | ret = fd_valid; | |
250 | error: | |
251 | return ret; | |
252 | } | |
253 | ||
6548fca4 MD |
254 | /* |
255 | * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd. | |
256 | * Has strict checking of fd validity. | |
f5c453e9 JR |
257 | * |
258 | * If fd <= 2, dup the fd until fd > 2. This enables us to bypass | |
259 | * problems that can be encountered if UST uses stdin, stdout, stderr | |
260 | * fds for internal use (daemon etc.). This can happen if the | |
261 | * application closes either of those file descriptors. Intermediary fds | |
262 | * are closed as needed. | |
263 | * | |
264 | * Return -1 on error. | |
265 | * | |
6548fca4 | 266 | */ |
f5c453e9 | 267 | int lttng_ust_add_fd_to_tracker(int fd) |
6548fca4 | 268 | { |
f5c453e9 | 269 | int ret; |
7d34f27d MD |
270 | /* |
271 | * Ensure the tracker is initialized when called from | |
272 | * constructors. | |
273 | */ | |
fca97dfd | 274 | lttng_ust_fd_tracker_init(); |
96a6162e | 275 | assert(URCU_TLS(ust_fd_mutex_nest)); |
f5c453e9 JR |
276 | |
277 | if (IS_FD_STD(fd)) { | |
278 | ret = dup_std_fd(fd); | |
279 | if (ret < 0) { | |
280 | goto error; | |
281 | } | |
282 | fd = ret; | |
283 | } | |
284 | ||
6548fca4 MD |
285 | /* Trying to add an fd which we can not accommodate. */ |
286 | assert(IS_FD_VALID(fd)); | |
287 | /* Setting an fd thats already set. */ | |
288 | assert(!IS_FD_SET(fd, lttng_fd_set)); | |
289 | ||
290 | ADD_FD_TO_SET(fd, lttng_fd_set); | |
f5c453e9 JR |
291 | return fd; |
292 | error: | |
293 | return ret; | |
6548fca4 MD |
294 | } |
295 | ||
296 | /* | |
297 | * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd. | |
298 | * Has strict checking for fd validity. | |
299 | */ | |
300 | void lttng_ust_delete_fd_from_tracker(int fd) | |
301 | { | |
7d34f27d MD |
302 | /* |
303 | * Ensure the tracker is initialized when called from | |
304 | * constructors. | |
305 | */ | |
fca97dfd | 306 | lttng_ust_fd_tracker_init(); |
7d34f27d | 307 | |
96a6162e | 308 | assert(URCU_TLS(ust_fd_mutex_nest)); |
6548fca4 MD |
309 | /* Not a valid fd. */ |
310 | assert(IS_FD_VALID(fd)); | |
311 | /* Deleting an fd which was not set. */ | |
312 | assert(IS_FD_SET(fd, lttng_fd_set)); | |
313 | ||
314 | DEL_FD_FROM_SET(fd, lttng_fd_set); | |
315 | } | |
316 | ||
317 | /* | |
318 | * Interface allowing applications to close arbitrary file descriptors. | |
319 | * We check if it is owned by lttng-ust, and return -1, errno=EBADF | |
320 | * instead of closing it if it is the case. | |
321 | */ | |
322 | int lttng_ust_safe_close_fd(int fd, int (*close_cb)(int fd)) | |
323 | { | |
324 | int ret = 0; | |
325 | ||
a9fd951a | 326 | lttng_ust_fd_tracker_alloc_tls(); |
6548fca4 | 327 | |
7d34f27d MD |
328 | /* |
329 | * Ensure the tracker is initialized when called from | |
330 | * constructors. | |
331 | */ | |
fca97dfd | 332 | lttng_ust_fd_tracker_init(); |
7d34f27d | 333 | |
6548fca4 MD |
334 | /* |
335 | * If called from lttng-ust, we directly call close without | |
336 | * validating whether the FD is part of the tracked set. | |
337 | */ | |
793d29c9 | 338 | if (URCU_TLS(ust_fd_mutex_nest)) |
6548fca4 MD |
339 | return close_cb(fd); |
340 | ||
341 | lttng_ust_lock_fd_tracker(); | |
342 | if (IS_FD_VALID(fd) && IS_FD_SET(fd, lttng_fd_set)) { | |
343 | ret = -1; | |
344 | errno = EBADF; | |
345 | } else { | |
346 | ret = close_cb(fd); | |
347 | } | |
348 | lttng_ust_unlock_fd_tracker(); | |
349 | ||
350 | return ret; | |
351 | } | |
352 | ||
52a20dc7 MD |
353 | /* |
354 | * Interface allowing applications to close arbitrary streams. | |
355 | * We check if it is owned by lttng-ust, and return -1, errno=EBADF | |
356 | * instead of closing it if it is the case. | |
357 | */ | |
358 | int lttng_ust_safe_fclose_stream(FILE *stream, int (*fclose_cb)(FILE *stream)) | |
359 | { | |
360 | int ret = 0, fd; | |
361 | ||
a9fd951a | 362 | lttng_ust_fd_tracker_alloc_tls(); |
52a20dc7 | 363 | |
7d34f27d MD |
364 | /* |
365 | * Ensure the tracker is initialized when called from | |
366 | * constructors. | |
367 | */ | |
fca97dfd | 368 | lttng_ust_fd_tracker_init(); |
7d34f27d | 369 | |
52a20dc7 MD |
370 | /* |
371 | * If called from lttng-ust, we directly call fclose without | |
372 | * validating whether the FD is part of the tracked set. | |
373 | */ | |
793d29c9 | 374 | if (URCU_TLS(ust_fd_mutex_nest)) |
52a20dc7 MD |
375 | return fclose_cb(stream); |
376 | ||
377 | fd = fileno(stream); | |
378 | ||
379 | lttng_ust_lock_fd_tracker(); | |
380 | if (IS_FD_VALID(fd) && IS_FD_SET(fd, lttng_fd_set)) { | |
381 | ret = -1; | |
382 | errno = EBADF; | |
383 | } else { | |
384 | ret = fclose_cb(stream); | |
385 | } | |
386 | lttng_ust_unlock_fd_tracker(); | |
387 | ||
388 | return ret; | |
389 | } | |
390 | ||
6548fca4 MD |
391 | #ifdef __OpenBSD__ |
392 | static void set_close_success(int *p) | |
393 | { | |
394 | *p = 1; | |
395 | } | |
396 | static int test_close_success(const int *p) | |
397 | { | |
398 | return *p; | |
399 | } | |
400 | #else | |
401 | static void set_close_success(int *p __attribute__((unused))) | |
402 | { | |
403 | } | |
404 | static int test_close_success(const int *p __attribute__((unused))) | |
405 | { | |
406 | return 1; | |
407 | } | |
408 | #endif | |
409 | ||
410 | /* | |
411 | * Implement helper for closefrom() override. | |
412 | */ | |
413 | int lttng_ust_safe_closefrom_fd(int lowfd, int (*close_cb)(int fd)) | |
414 | { | |
415 | int ret = 0, close_success = 0, i; | |
416 | ||
a9fd951a | 417 | lttng_ust_fd_tracker_alloc_tls(); |
6548fca4 | 418 | |
7d34f27d MD |
419 | /* |
420 | * Ensure the tracker is initialized when called from | |
421 | * constructors. | |
422 | */ | |
fca97dfd | 423 | lttng_ust_fd_tracker_init(); |
7d34f27d | 424 | |
6548fca4 MD |
425 | if (lowfd < 0) { |
426 | /* | |
427 | * NetBSD return EBADF if fd is invalid. | |
428 | */ | |
429 | errno = EBADF; | |
430 | ret = -1; | |
431 | goto end; | |
432 | } | |
433 | /* | |
434 | * If called from lttng-ust, we directly call close without | |
435 | * validating whether the FD is part of the tracked set. | |
436 | */ | |
793d29c9 | 437 | if (URCU_TLS(ust_fd_mutex_nest)) { |
6548fca4 MD |
438 | for (i = lowfd; i < lttng_ust_max_fd; i++) { |
439 | if (close_cb(i) < 0) { | |
440 | switch (errno) { | |
441 | case EBADF: | |
442 | continue; | |
443 | case EINTR: | |
444 | default: | |
445 | ret = -1; | |
446 | goto end; | |
447 | } | |
448 | } | |
449 | set_close_success(&close_success); | |
450 | } | |
451 | } else { | |
452 | lttng_ust_lock_fd_tracker(); | |
453 | for (i = lowfd; i < lttng_ust_max_fd; i++) { | |
454 | if (IS_FD_VALID(i) && IS_FD_SET(i, lttng_fd_set)) | |
455 | continue; | |
456 | if (close_cb(i) < 0) { | |
457 | switch (errno) { | |
458 | case EBADF: | |
459 | continue; | |
460 | case EINTR: | |
461 | default: | |
462 | ret = -1; | |
463 | lttng_ust_unlock_fd_tracker(); | |
464 | goto end; | |
465 | } | |
466 | } | |
467 | set_close_success(&close_success); | |
468 | } | |
469 | lttng_ust_unlock_fd_tracker(); | |
470 | } | |
471 | if (!test_close_success(&close_success)) { | |
472 | /* | |
473 | * OpenBSD return EBADF if fd is greater than all open | |
474 | * file descriptors. | |
475 | */ | |
476 | ret = -1; | |
477 | errno = EBADF; | |
478 | } | |
479 | end: | |
480 | return ret; | |
481 | } |