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 MD |
27 | |
28 | #include <ust-fd.h> | |
864a1eda | 29 | #include <ust-helper.h> |
6548fca4 MD |
30 | #include <lttng/ust-error.h> |
31 | #include <usterr-signal-safe.h> | |
32 | ||
33 | #include "../liblttng-ust/compat.h" | |
4b4a1337 | 34 | #include "../liblttng-ust/lttng-tracer-core.h" |
6548fca4 MD |
35 | |
36 | /* Operations on the fd set. */ | |
37 | #define IS_FD_VALID(fd) ((fd) >= 0 && (fd) < lttng_ust_max_fd) | |
38 | #define GET_FD_SET_FOR_FD(fd, fd_sets) (&((fd_sets)[(fd) / FD_SETSIZE])) | |
39 | #define CALC_INDEX_TO_SET(fd) ((fd) % FD_SETSIZE) | |
f5c453e9 | 40 | #define IS_FD_STD(fd) (IS_FD_VALID(fd) && (fd) <= STDERR_FILENO) |
6548fca4 MD |
41 | |
42 | /* Check fd validity before calling these. */ | |
43 | #define ADD_FD_TO_SET(fd, fd_sets) \ | |
44 | FD_SET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
45 | #define IS_FD_SET(fd, fd_sets) \ | |
46 | FD_ISSET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
47 | #define DEL_FD_FROM_SET(fd, fd_sets) \ | |
48 | FD_CLR(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
49 | ||
50 | /* | |
51 | * Protect the lttng_fd_set. Nests within the ust_lock, and therefore | |
52 | * within the libc dl lock. Therefore, we need to fixup the TLS before | |
53 | * nesting into this lock. | |
c1be081a MD |
54 | * |
55 | * The ust_safe_guard_fd_mutex nests within the ust_mutex. This mutex | |
56 | * is also held across fork. | |
6548fca4 MD |
57 | */ |
58 | static pthread_mutex_t ust_safe_guard_fd_mutex = PTHREAD_MUTEX_INITIALIZER; | |
283f4bec MD |
59 | |
60 | /* | |
61 | * Cancel state when grabbing the ust_safe_guard_fd_mutex. Saved when | |
62 | * locking, restored on unlock. Protected by ust_safe_guard_fd_mutex. | |
63 | */ | |
64 | static int ust_safe_guard_saved_cancelstate; | |
65 | ||
6548fca4 MD |
66 | /* |
67 | * Track whether we are within lttng-ust or application, for close | |
793d29c9 MD |
68 | * system call override by LD_PRELOAD library. This also tracks whether |
69 | * we are invoking close() from a signal handler nested on an | |
70 | * application thread. | |
6548fca4 | 71 | */ |
96a6162e | 72 | static DEFINE_URCU_TLS(int, ust_fd_mutex_nest); |
6548fca4 MD |
73 | |
74 | /* fd_set used to book keep fd being used by lttng-ust. */ | |
75 | static fd_set *lttng_fd_set; | |
76 | static int lttng_ust_max_fd; | |
77 | static int num_fd_sets; | |
7d34f27d | 78 | static int init_done; |
6548fca4 MD |
79 | |
80 | /* | |
81 | * Force a read (imply TLS fixup for dlopen) of TLS variables. | |
82 | */ | |
83 | void lttng_ust_fixup_fd_tracker_tls(void) | |
84 | { | |
96a6162e | 85 | asm volatile ("" : : "m" (URCU_TLS(ust_fd_mutex_nest))); |
6548fca4 MD |
86 | } |
87 | ||
88 | /* | |
89 | * Allocate the fd set array based on the hard limit set for this | |
90 | * process. This will be called during the constructor execution | |
91 | * and will also be called in the child after fork via lttng_ust_init. | |
92 | */ | |
93 | void lttng_ust_init_fd_tracker(void) | |
94 | { | |
95 | struct rlimit rlim; | |
96 | int i; | |
97 | ||
7d34f27d MD |
98 | if (CMM_LOAD_SHARED(init_done)) |
99 | return; | |
100 | ||
6548fca4 MD |
101 | memset(&rlim, 0, sizeof(rlim)); |
102 | /* Get the current possible max number of fd for this process. */ | |
103 | if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) | |
104 | abort(); | |
105 | /* | |
106 | * FD set array size determined using the hard limit. Even if | |
107 | * the process wishes to increase its limit using setrlimit, it | |
108 | * can only do so with the softlimit which will be less than the | |
109 | * hard limit. | |
110 | */ | |
111 | lttng_ust_max_fd = rlim.rlim_max; | |
112 | num_fd_sets = lttng_ust_max_fd / FD_SETSIZE; | |
113 | if (lttng_ust_max_fd % FD_SETSIZE) | |
114 | ++num_fd_sets; | |
115 | if (lttng_fd_set != NULL) { | |
116 | free(lttng_fd_set); | |
117 | lttng_fd_set = NULL; | |
118 | } | |
119 | lttng_fd_set = malloc(num_fd_sets * (sizeof(fd_set))); | |
120 | if (!lttng_fd_set) | |
121 | abort(); | |
122 | for (i = 0; i < num_fd_sets; i++) | |
123 | FD_ZERO((<tng_fd_set[i])); | |
7d34f27d | 124 | CMM_STORE_SHARED(init_done, 1); |
6548fca4 MD |
125 | } |
126 | ||
127 | void lttng_ust_lock_fd_tracker(void) | |
128 | { | |
96a6162e | 129 | sigset_t sig_all_blocked, orig_mask; |
283f4bec MD |
130 | int ret, oldstate; |
131 | ||
132 | ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate); | |
133 | if (ret) { | |
134 | ERR("pthread_setcancelstate: %s", strerror(ret)); | |
135 | } | |
96a6162e MD |
136 | sigfillset(&sig_all_blocked); |
137 | ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask); | |
138 | if (ret) { | |
139 | ERR("pthread_sigmask: %s", strerror(ret)); | |
140 | } | |
141 | if (!URCU_TLS(ust_fd_mutex_nest)++) { | |
142 | /* | |
143 | * Ensure the compiler don't move the store after the close() | |
144 | * call in case close() would be marked as leaf. | |
145 | */ | |
146 | cmm_barrier(); | |
147 | pthread_mutex_lock(&ust_safe_guard_fd_mutex); | |
148 | ust_safe_guard_saved_cancelstate = oldstate; | |
149 | } | |
150 | ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL); | |
151 | if (ret) { | |
152 | ERR("pthread_sigmask: %s", strerror(ret)); | |
153 | } | |
6548fca4 MD |
154 | } |
155 | ||
156 | void lttng_ust_unlock_fd_tracker(void) | |
157 | { | |
96a6162e | 158 | sigset_t sig_all_blocked, orig_mask; |
283f4bec | 159 | int ret, newstate, oldstate; |
96a6162e | 160 | bool restore_cancel = false; |
283f4bec | 161 | |
96a6162e MD |
162 | sigfillset(&sig_all_blocked); |
163 | ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask); | |
164 | if (ret) { | |
165 | ERR("pthread_sigmask: %s", strerror(ret)); | |
166 | } | |
6548fca4 MD |
167 | /* |
168 | * Ensure the compiler don't move the store before the close() | |
169 | * call, in case close() would be marked as leaf. | |
170 | */ | |
171 | cmm_barrier(); | |
96a6162e MD |
172 | if (!--URCU_TLS(ust_fd_mutex_nest)) { |
173 | newstate = ust_safe_guard_saved_cancelstate; | |
174 | restore_cancel = true; | |
175 | pthread_mutex_unlock(&ust_safe_guard_fd_mutex); | |
176 | } | |
177 | ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL); | |
283f4bec | 178 | if (ret) { |
96a6162e MD |
179 | ERR("pthread_sigmask: %s", strerror(ret)); |
180 | } | |
181 | if (restore_cancel) { | |
182 | ret = pthread_setcancelstate(newstate, &oldstate); | |
183 | if (ret) { | |
184 | ERR("pthread_setcancelstate: %s", strerror(ret)); | |
185 | } | |
283f4bec | 186 | } |
6548fca4 MD |
187 | } |
188 | ||
f5c453e9 JR |
189 | static int dup_std_fd(int fd) |
190 | { | |
5a4d96d1 | 191 | int ret, i; |
f5c453e9 JR |
192 | int fd_to_close[STDERR_FILENO + 1]; |
193 | int fd_to_close_count = 0; | |
194 | int dup_cmd = F_DUPFD; /* Default command */ | |
195 | int fd_valid = -1; | |
196 | ||
197 | if (!(IS_FD_STD(fd))) { | |
198 | /* Should not be here */ | |
199 | ret = -1; | |
200 | goto error; | |
201 | } | |
202 | ||
203 | /* Check for FD_CLOEXEC flag */ | |
204 | ret = fcntl(fd, F_GETFD); | |
205 | if (ret < 0) { | |
206 | PERROR("fcntl on f_getfd"); | |
207 | ret = -1; | |
208 | goto error; | |
209 | } | |
210 | ||
211 | if (ret & FD_CLOEXEC) { | |
212 | dup_cmd = F_DUPFD_CLOEXEC; | |
213 | } | |
214 | ||
215 | /* Perform dup */ | |
5a4d96d1 | 216 | for (i = 0; i < STDERR_FILENO + 1; i++) { |
f5c453e9 JR |
217 | ret = fcntl(fd, dup_cmd, 0); |
218 | if (ret < 0) { | |
219 | PERROR("fcntl dup fd"); | |
220 | goto error; | |
221 | } | |
222 | ||
223 | if (!(IS_FD_STD(ret))) { | |
224 | /* fd is outside of STD range, use it. */ | |
225 | fd_valid = ret; | |
226 | /* Close fd received as argument. */ | |
227 | fd_to_close[i] = fd; | |
228 | fd_to_close_count++; | |
229 | break; | |
230 | } | |
231 | ||
232 | fd_to_close[i] = ret; | |
233 | fd_to_close_count++; | |
234 | } | |
235 | ||
236 | /* Close intermediary fds */ | |
5a4d96d1 | 237 | for (i = 0; i < fd_to_close_count; i++) { |
f5c453e9 JR |
238 | ret = close(fd_to_close[i]); |
239 | if (ret) { | |
240 | PERROR("close on temporary fd: %d.", fd_to_close[i]); | |
241 | /* | |
242 | * Not using an abort here would yield a complicated | |
243 | * error handling for the caller. If a failure occurs | |
244 | * here, the system is already in a bad state. | |
245 | */ | |
246 | abort(); | |
247 | } | |
248 | } | |
249 | ||
250 | ret = fd_valid; | |
251 | error: | |
252 | return ret; | |
253 | } | |
254 | ||
6548fca4 MD |
255 | /* |
256 | * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd. | |
257 | * Has strict checking of fd validity. | |
f5c453e9 JR |
258 | * |
259 | * If fd <= 2, dup the fd until fd > 2. This enables us to bypass | |
260 | * problems that can be encountered if UST uses stdin, stdout, stderr | |
261 | * fds for internal use (daemon etc.). This can happen if the | |
262 | * application closes either of those file descriptors. Intermediary fds | |
263 | * are closed as needed. | |
264 | * | |
265 | * Return -1 on error. | |
266 | * | |
6548fca4 | 267 | */ |
f5c453e9 | 268 | int lttng_ust_add_fd_to_tracker(int fd) |
6548fca4 | 269 | { |
f5c453e9 | 270 | int ret; |
7d34f27d MD |
271 | /* |
272 | * Ensure the tracker is initialized when called from | |
273 | * constructors. | |
274 | */ | |
275 | lttng_ust_init_fd_tracker(); | |
96a6162e | 276 | assert(URCU_TLS(ust_fd_mutex_nest)); |
f5c453e9 JR |
277 | |
278 | if (IS_FD_STD(fd)) { | |
279 | ret = dup_std_fd(fd); | |
280 | if (ret < 0) { | |
281 | goto error; | |
282 | } | |
283 | fd = ret; | |
284 | } | |
285 | ||
6548fca4 MD |
286 | /* Trying to add an fd which we can not accommodate. */ |
287 | assert(IS_FD_VALID(fd)); | |
288 | /* Setting an fd thats already set. */ | |
289 | assert(!IS_FD_SET(fd, lttng_fd_set)); | |
290 | ||
291 | ADD_FD_TO_SET(fd, lttng_fd_set); | |
f5c453e9 JR |
292 | return fd; |
293 | error: | |
294 | return ret; | |
6548fca4 MD |
295 | } |
296 | ||
297 | /* | |
298 | * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd. | |
299 | * Has strict checking for fd validity. | |
300 | */ | |
301 | void lttng_ust_delete_fd_from_tracker(int fd) | |
302 | { | |
7d34f27d MD |
303 | /* |
304 | * Ensure the tracker is initialized when called from | |
305 | * constructors. | |
306 | */ | |
307 | lttng_ust_init_fd_tracker(); | |
308 | ||
96a6162e | 309 | assert(URCU_TLS(ust_fd_mutex_nest)); |
6548fca4 MD |
310 | /* Not a valid fd. */ |
311 | assert(IS_FD_VALID(fd)); | |
312 | /* Deleting an fd which was not set. */ | |
313 | assert(IS_FD_SET(fd, lttng_fd_set)); | |
314 | ||
315 | DEL_FD_FROM_SET(fd, lttng_fd_set); | |
316 | } | |
317 | ||
318 | /* | |
319 | * Interface allowing applications to close arbitrary file descriptors. | |
320 | * We check if it is owned by lttng-ust, and return -1, errno=EBADF | |
321 | * instead of closing it if it is the case. | |
322 | */ | |
323 | int lttng_ust_safe_close_fd(int fd, int (*close_cb)(int fd)) | |
324 | { | |
325 | int ret = 0; | |
326 | ||
327 | lttng_ust_fixup_fd_tracker_tls(); | |
328 | ||
7d34f27d MD |
329 | /* |
330 | * Ensure the tracker is initialized when called from | |
331 | * constructors. | |
332 | */ | |
333 | lttng_ust_init_fd_tracker(); | |
334 | ||
6548fca4 MD |
335 | /* |
336 | * If called from lttng-ust, we directly call close without | |
337 | * validating whether the FD is part of the tracked set. | |
338 | */ | |
793d29c9 | 339 | if (URCU_TLS(ust_fd_mutex_nest)) |
6548fca4 MD |
340 | return close_cb(fd); |
341 | ||
342 | lttng_ust_lock_fd_tracker(); | |
343 | if (IS_FD_VALID(fd) && IS_FD_SET(fd, lttng_fd_set)) { | |
344 | ret = -1; | |
345 | errno = EBADF; | |
346 | } else { | |
347 | ret = close_cb(fd); | |
348 | } | |
349 | lttng_ust_unlock_fd_tracker(); | |
350 | ||
351 | return ret; | |
352 | } | |
353 | ||
52a20dc7 MD |
354 | /* |
355 | * Interface allowing applications to close arbitrary streams. | |
356 | * We check if it is owned by lttng-ust, and return -1, errno=EBADF | |
357 | * instead of closing it if it is the case. | |
358 | */ | |
359 | int lttng_ust_safe_fclose_stream(FILE *stream, int (*fclose_cb)(FILE *stream)) | |
360 | { | |
361 | int ret = 0, fd; | |
362 | ||
363 | lttng_ust_fixup_fd_tracker_tls(); | |
364 | ||
7d34f27d MD |
365 | /* |
366 | * Ensure the tracker is initialized when called from | |
367 | * constructors. | |
368 | */ | |
369 | lttng_ust_init_fd_tracker(); | |
370 | ||
52a20dc7 MD |
371 | /* |
372 | * If called from lttng-ust, we directly call fclose without | |
373 | * validating whether the FD is part of the tracked set. | |
374 | */ | |
793d29c9 | 375 | if (URCU_TLS(ust_fd_mutex_nest)) |
52a20dc7 MD |
376 | return fclose_cb(stream); |
377 | ||
378 | fd = fileno(stream); | |
379 | ||
380 | lttng_ust_lock_fd_tracker(); | |
381 | if (IS_FD_VALID(fd) && IS_FD_SET(fd, lttng_fd_set)) { | |
382 | ret = -1; | |
383 | errno = EBADF; | |
384 | } else { | |
385 | ret = fclose_cb(stream); | |
386 | } | |
387 | lttng_ust_unlock_fd_tracker(); | |
388 | ||
389 | return ret; | |
390 | } | |
391 | ||
6548fca4 MD |
392 | #ifdef __OpenBSD__ |
393 | static void set_close_success(int *p) | |
394 | { | |
395 | *p = 1; | |
396 | } | |
397 | static int test_close_success(const int *p) | |
398 | { | |
399 | return *p; | |
400 | } | |
401 | #else | |
402 | static void set_close_success(int *p __attribute__((unused))) | |
403 | { | |
404 | } | |
405 | static int test_close_success(const int *p __attribute__((unused))) | |
406 | { | |
407 | return 1; | |
408 | } | |
409 | #endif | |
410 | ||
411 | /* | |
412 | * Implement helper for closefrom() override. | |
413 | */ | |
414 | int lttng_ust_safe_closefrom_fd(int lowfd, int (*close_cb)(int fd)) | |
415 | { | |
416 | int ret = 0, close_success = 0, i; | |
417 | ||
418 | lttng_ust_fixup_fd_tracker_tls(); | |
419 | ||
7d34f27d MD |
420 | /* |
421 | * Ensure the tracker is initialized when called from | |
422 | * constructors. | |
423 | */ | |
424 | lttng_ust_init_fd_tracker(); | |
425 | ||
6548fca4 MD |
426 | if (lowfd < 0) { |
427 | /* | |
428 | * NetBSD return EBADF if fd is invalid. | |
429 | */ | |
430 | errno = EBADF; | |
431 | ret = -1; | |
432 | goto end; | |
433 | } | |
434 | /* | |
435 | * If called from lttng-ust, we directly call close without | |
436 | * validating whether the FD is part of the tracked set. | |
437 | */ | |
793d29c9 | 438 | if (URCU_TLS(ust_fd_mutex_nest)) { |
6548fca4 MD |
439 | for (i = lowfd; i < lttng_ust_max_fd; i++) { |
440 | if (close_cb(i) < 0) { | |
441 | switch (errno) { | |
442 | case EBADF: | |
443 | continue; | |
444 | case EINTR: | |
445 | default: | |
446 | ret = -1; | |
447 | goto end; | |
448 | } | |
449 | } | |
450 | set_close_success(&close_success); | |
451 | } | |
452 | } else { | |
453 | lttng_ust_lock_fd_tracker(); | |
454 | for (i = lowfd; i < lttng_ust_max_fd; i++) { | |
455 | if (IS_FD_VALID(i) && IS_FD_SET(i, lttng_fd_set)) | |
456 | continue; | |
457 | if (close_cb(i) < 0) { | |
458 | switch (errno) { | |
459 | case EBADF: | |
460 | continue; | |
461 | case EINTR: | |
462 | default: | |
463 | ret = -1; | |
464 | lttng_ust_unlock_fd_tracker(); | |
465 | goto end; | |
466 | } | |
467 | } | |
468 | set_close_success(&close_success); | |
469 | } | |
470 | lttng_ust_unlock_fd_tracker(); | |
471 | } | |
472 | if (!test_close_success(&close_success)) { | |
473 | /* | |
474 | * OpenBSD return EBADF if fd is greater than all open | |
475 | * file descriptors. | |
476 | */ | |
477 | ret = -1; | |
478 | errno = EBADF; | |
479 | } | |
480 | end: | |
481 | return ret; | |
482 | } |