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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> | |
35 | #include <urcu/compiler.h> | |
36 | #include <urcu/tls-compat.h> | |
d5bfffd2 | 37 | #include <urcu/system.h> |
6548fca4 MD |
38 | |
39 | #include <ust-fd.h> | |
40 | #include <helper.h> | |
41 | #include <lttng/ust-error.h> | |
42 | #include <usterr-signal-safe.h> | |
43 | ||
44 | #include "../liblttng-ust/compat.h" | |
45 | ||
46 | /* Operations on the fd set. */ | |
47 | #define IS_FD_VALID(fd) ((fd) >= 0 && (fd) < lttng_ust_max_fd) | |
48 | #define GET_FD_SET_FOR_FD(fd, fd_sets) (&((fd_sets)[(fd) / FD_SETSIZE])) | |
49 | #define CALC_INDEX_TO_SET(fd) ((fd) % FD_SETSIZE) | |
0dd6b494 | 50 | #define IS_FD_STD(fd) (IS_FD_VALID(fd) && (fd) <= STDERR_FILENO) |
6548fca4 MD |
51 | |
52 | /* Check fd validity before calling these. */ | |
53 | #define ADD_FD_TO_SET(fd, fd_sets) \ | |
54 | FD_SET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
55 | #define IS_FD_SET(fd, fd_sets) \ | |
56 | FD_ISSET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
57 | #define DEL_FD_FROM_SET(fd, fd_sets) \ | |
58 | FD_CLR(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
59 | ||
60 | /* | |
61 | * Protect the lttng_fd_set. Nests within the ust_lock, and therefore | |
62 | * within the libc dl lock. Therefore, we need to fixup the TLS before | |
63 | * nesting into this lock. | |
791bf273 MD |
64 | * |
65 | * The ust_safe_guard_fd_mutex nests within the ust_mutex. This mutex | |
66 | * is also held across fork. | |
6548fca4 MD |
67 | */ |
68 | static pthread_mutex_t ust_safe_guard_fd_mutex = PTHREAD_MUTEX_INITIALIZER; | |
69 | /* | |
70 | * Track whether we are within lttng-ust or application, for close | |
71 | * system call override by LD_PRELOAD library. | |
72 | */ | |
73 | static DEFINE_URCU_TLS(int, thread_fd_tracking); | |
74 | ||
75 | /* fd_set used to book keep fd being used by lttng-ust. */ | |
76 | static fd_set *lttng_fd_set; | |
77 | static int lttng_ust_max_fd; | |
78 | static int num_fd_sets; | |
d5bfffd2 | 79 | static int init_done; |
6548fca4 MD |
80 | |
81 | /* | |
82 | * Force a read (imply TLS fixup for dlopen) of TLS variables. | |
83 | */ | |
84 | void lttng_ust_fixup_fd_tracker_tls(void) | |
85 | { | |
86 | asm volatile ("" : : "m" (URCU_TLS(thread_fd_tracking))); | |
87 | } | |
88 | ||
89 | /* | |
90 | * Allocate the fd set array based on the hard limit set for this | |
91 | * process. This will be called during the constructor execution | |
92 | * and will also be called in the child after fork via lttng_ust_init. | |
93 | */ | |
94 | void lttng_ust_init_fd_tracker(void) | |
95 | { | |
96 | struct rlimit rlim; | |
97 | int i; | |
98 | ||
d5bfffd2 MD |
99 | if (CMM_LOAD_SHARED(init_done)) |
100 | return; | |
101 | ||
6548fca4 MD |
102 | memset(&rlim, 0, sizeof(rlim)); |
103 | /* Get the current possible max number of fd for this process. */ | |
104 | if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) | |
105 | abort(); | |
106 | /* | |
107 | * FD set array size determined using the hard limit. Even if | |
108 | * the process wishes to increase its limit using setrlimit, it | |
109 | * can only do so with the softlimit which will be less than the | |
110 | * hard limit. | |
111 | */ | |
112 | lttng_ust_max_fd = rlim.rlim_max; | |
113 | num_fd_sets = lttng_ust_max_fd / FD_SETSIZE; | |
114 | if (lttng_ust_max_fd % FD_SETSIZE) | |
115 | ++num_fd_sets; | |
116 | if (lttng_fd_set != NULL) { | |
117 | free(lttng_fd_set); | |
118 | lttng_fd_set = NULL; | |
119 | } | |
120 | lttng_fd_set = malloc(num_fd_sets * (sizeof(fd_set))); | |
121 | if (!lttng_fd_set) | |
122 | abort(); | |
123 | for (i = 0; i < num_fd_sets; i++) | |
124 | FD_ZERO((<tng_fd_set[i])); | |
d5bfffd2 | 125 | CMM_STORE_SHARED(init_done, 1); |
6548fca4 MD |
126 | } |
127 | ||
128 | void lttng_ust_lock_fd_tracker(void) | |
129 | { | |
130 | URCU_TLS(thread_fd_tracking) = 1; | |
131 | /* | |
132 | * Ensure the compiler don't move the store after the close() | |
133 | * call in case close() would be marked as leaf. | |
134 | */ | |
135 | cmm_barrier(); | |
136 | pthread_mutex_lock(&ust_safe_guard_fd_mutex); | |
137 | } | |
138 | ||
139 | void lttng_ust_unlock_fd_tracker(void) | |
140 | { | |
141 | pthread_mutex_unlock(&ust_safe_guard_fd_mutex); | |
142 | /* | |
143 | * Ensure the compiler don't move the store before the close() | |
144 | * call, in case close() would be marked as leaf. | |
145 | */ | |
146 | cmm_barrier(); | |
147 | URCU_TLS(thread_fd_tracking) = 0; | |
148 | } | |
149 | ||
0dd6b494 JR |
150 | static int dup_std_fd(int fd) |
151 | { | |
46e08d2c | 152 | int ret, i; |
0dd6b494 JR |
153 | int fd_to_close[STDERR_FILENO + 1]; |
154 | int fd_to_close_count = 0; | |
155 | int dup_cmd = F_DUPFD; /* Default command */ | |
156 | int fd_valid = -1; | |
157 | ||
158 | if (!(IS_FD_STD(fd))) { | |
159 | /* Should not be here */ | |
160 | ret = -1; | |
161 | goto error; | |
162 | } | |
163 | ||
164 | /* Check for FD_CLOEXEC flag */ | |
165 | ret = fcntl(fd, F_GETFD); | |
166 | if (ret < 0) { | |
167 | PERROR("fcntl on f_getfd"); | |
168 | ret = -1; | |
169 | goto error; | |
170 | } | |
171 | ||
172 | if (ret & FD_CLOEXEC) { | |
173 | dup_cmd = F_DUPFD_CLOEXEC; | |
174 | } | |
175 | ||
176 | /* Perform dup */ | |
46e08d2c | 177 | for (i = 0; i < STDERR_FILENO + 1; i++) { |
0dd6b494 JR |
178 | ret = fcntl(fd, dup_cmd, 0); |
179 | if (ret < 0) { | |
180 | PERROR("fcntl dup fd"); | |
181 | goto error; | |
182 | } | |
183 | ||
184 | if (!(IS_FD_STD(ret))) { | |
185 | /* fd is outside of STD range, use it. */ | |
186 | fd_valid = ret; | |
187 | /* Close fd received as argument. */ | |
188 | fd_to_close[i] = fd; | |
189 | fd_to_close_count++; | |
190 | break; | |
191 | } | |
192 | ||
193 | fd_to_close[i] = ret; | |
194 | fd_to_close_count++; | |
195 | } | |
196 | ||
197 | /* Close intermediary fds */ | |
46e08d2c | 198 | for (i = 0; i < fd_to_close_count; i++) { |
0dd6b494 JR |
199 | ret = close(fd_to_close[i]); |
200 | if (ret) { | |
201 | PERROR("close on temporary fd: %d.", fd_to_close[i]); | |
202 | /* | |
203 | * Not using an abort here would yield a complicated | |
204 | * error handling for the caller. If a failure occurs | |
205 | * here, the system is already in a bad state. | |
206 | */ | |
207 | abort(); | |
208 | } | |
209 | } | |
210 | ||
211 | ret = fd_valid; | |
212 | error: | |
213 | return ret; | |
214 | } | |
215 | ||
6548fca4 MD |
216 | /* |
217 | * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd. | |
218 | * Has strict checking of fd validity. | |
0dd6b494 JR |
219 | * |
220 | * If fd <= 2, dup the fd until fd > 2. This enables us to bypass | |
221 | * problems that can be encountered if UST uses stdin, stdout, stderr | |
222 | * fds for internal use (daemon etc.). This can happen if the | |
223 | * application closes either of those file descriptors. Intermediary fds | |
224 | * are closed as needed. | |
225 | * | |
226 | * Return -1 on error. | |
227 | * | |
6548fca4 | 228 | */ |
0dd6b494 | 229 | int lttng_ust_add_fd_to_tracker(int fd) |
6548fca4 | 230 | { |
0dd6b494 | 231 | int ret; |
d5bfffd2 MD |
232 | /* |
233 | * Ensure the tracker is initialized when called from | |
234 | * constructors. | |
235 | */ | |
236 | lttng_ust_init_fd_tracker(); | |
6548fca4 | 237 | assert(URCU_TLS(thread_fd_tracking)); |
0dd6b494 JR |
238 | |
239 | if (IS_FD_STD(fd)) { | |
240 | ret = dup_std_fd(fd); | |
241 | if (ret < 0) { | |
242 | goto error; | |
243 | } | |
244 | fd = ret; | |
245 | } | |
246 | ||
6548fca4 MD |
247 | /* Trying to add an fd which we can not accommodate. */ |
248 | assert(IS_FD_VALID(fd)); | |
249 | /* Setting an fd thats already set. */ | |
250 | assert(!IS_FD_SET(fd, lttng_fd_set)); | |
251 | ||
252 | ADD_FD_TO_SET(fd, lttng_fd_set); | |
0dd6b494 JR |
253 | return fd; |
254 | error: | |
255 | return ret; | |
6548fca4 MD |
256 | } |
257 | ||
258 | /* | |
259 | * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd. | |
260 | * Has strict checking for fd validity. | |
261 | */ | |
262 | void lttng_ust_delete_fd_from_tracker(int fd) | |
263 | { | |
d5bfffd2 MD |
264 | /* |
265 | * Ensure the tracker is initialized when called from | |
266 | * constructors. | |
267 | */ | |
268 | lttng_ust_init_fd_tracker(); | |
269 | ||
6548fca4 MD |
270 | assert(URCU_TLS(thread_fd_tracking)); |
271 | /* Not a valid fd. */ | |
272 | assert(IS_FD_VALID(fd)); | |
273 | /* Deleting an fd which was not set. */ | |
274 | assert(IS_FD_SET(fd, lttng_fd_set)); | |
275 | ||
276 | DEL_FD_FROM_SET(fd, lttng_fd_set); | |
277 | } | |
278 | ||
279 | /* | |
280 | * Interface allowing applications to close arbitrary file descriptors. | |
281 | * We check if it is owned by lttng-ust, and return -1, errno=EBADF | |
282 | * instead of closing it if it is the case. | |
283 | */ | |
284 | int lttng_ust_safe_close_fd(int fd, int (*close_cb)(int fd)) | |
285 | { | |
286 | int ret = 0; | |
287 | ||
288 | lttng_ust_fixup_fd_tracker_tls(); | |
289 | ||
d5bfffd2 MD |
290 | /* |
291 | * Ensure the tracker is initialized when called from | |
292 | * constructors. | |
293 | */ | |
294 | lttng_ust_init_fd_tracker(); | |
295 | ||
6548fca4 MD |
296 | /* |
297 | * If called from lttng-ust, we directly call close without | |
298 | * validating whether the FD is part of the tracked set. | |
299 | */ | |
300 | if (URCU_TLS(thread_fd_tracking)) | |
301 | return close_cb(fd); | |
302 | ||
303 | lttng_ust_lock_fd_tracker(); | |
304 | if (IS_FD_VALID(fd) && IS_FD_SET(fd, lttng_fd_set)) { | |
305 | ret = -1; | |
306 | errno = EBADF; | |
307 | } else { | |
308 | ret = close_cb(fd); | |
309 | } | |
310 | lttng_ust_unlock_fd_tracker(); | |
311 | ||
312 | return ret; | |
313 | } | |
314 | ||
1b865e7e MD |
315 | /* |
316 | * Interface allowing applications to close arbitrary streams. | |
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_fclose_stream(FILE *stream, int (*fclose_cb)(FILE *stream)) | |
321 | { | |
322 | int ret = 0, fd; | |
323 | ||
324 | lttng_ust_fixup_fd_tracker_tls(); | |
325 | ||
d5bfffd2 MD |
326 | /* |
327 | * Ensure the tracker is initialized when called from | |
328 | * constructors. | |
329 | */ | |
330 | lttng_ust_init_fd_tracker(); | |
331 | ||
1b865e7e MD |
332 | /* |
333 | * If called from lttng-ust, we directly call fclose without | |
334 | * validating whether the FD is part of the tracked set. | |
335 | */ | |
336 | if (URCU_TLS(thread_fd_tracking)) | |
337 | return fclose_cb(stream); | |
338 | ||
339 | fd = fileno(stream); | |
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 = fclose_cb(stream); | |
347 | } | |
348 | lttng_ust_unlock_fd_tracker(); | |
349 | ||
350 | return ret; | |
351 | } | |
352 | ||
6548fca4 MD |
353 | #ifdef __OpenBSD__ |
354 | static void set_close_success(int *p) | |
355 | { | |
356 | *p = 1; | |
357 | } | |
358 | static int test_close_success(const int *p) | |
359 | { | |
360 | return *p; | |
361 | } | |
362 | #else | |
363 | static void set_close_success(int *p __attribute__((unused))) | |
364 | { | |
365 | } | |
366 | static int test_close_success(const int *p __attribute__((unused))) | |
367 | { | |
368 | return 1; | |
369 | } | |
370 | #endif | |
371 | ||
372 | /* | |
373 | * Implement helper for closefrom() override. | |
374 | */ | |
375 | int lttng_ust_safe_closefrom_fd(int lowfd, int (*close_cb)(int fd)) | |
376 | { | |
377 | int ret = 0, close_success = 0, i; | |
378 | ||
379 | lttng_ust_fixup_fd_tracker_tls(); | |
380 | ||
d5bfffd2 MD |
381 | /* |
382 | * Ensure the tracker is initialized when called from | |
383 | * constructors. | |
384 | */ | |
385 | lttng_ust_init_fd_tracker(); | |
386 | ||
6548fca4 MD |
387 | if (lowfd < 0) { |
388 | /* | |
389 | * NetBSD return EBADF if fd is invalid. | |
390 | */ | |
391 | errno = EBADF; | |
392 | ret = -1; | |
393 | goto end; | |
394 | } | |
395 | /* | |
396 | * If called from lttng-ust, we directly call close without | |
397 | * validating whether the FD is part of the tracked set. | |
398 | */ | |
399 | if (URCU_TLS(thread_fd_tracking)) { | |
400 | for (i = lowfd; i < lttng_ust_max_fd; i++) { | |
401 | if (close_cb(i) < 0) { | |
402 | switch (errno) { | |
403 | case EBADF: | |
404 | continue; | |
405 | case EINTR: | |
406 | default: | |
407 | ret = -1; | |
408 | goto end; | |
409 | } | |
410 | } | |
411 | set_close_success(&close_success); | |
412 | } | |
413 | } else { | |
414 | lttng_ust_lock_fd_tracker(); | |
415 | for (i = lowfd; i < lttng_ust_max_fd; i++) { | |
416 | if (IS_FD_VALID(i) && IS_FD_SET(i, lttng_fd_set)) | |
417 | continue; | |
418 | if (close_cb(i) < 0) { | |
419 | switch (errno) { | |
420 | case EBADF: | |
421 | continue; | |
422 | case EINTR: | |
423 | default: | |
424 | ret = -1; | |
425 | lttng_ust_unlock_fd_tracker(); | |
426 | goto end; | |
427 | } | |
428 | } | |
429 | set_close_success(&close_success); | |
430 | } | |
431 | lttng_ust_unlock_fd_tracker(); | |
432 | } | |
433 | if (!test_close_success(&close_success)) { | |
434 | /* | |
435 | * OpenBSD return EBADF if fd is greater than all open | |
436 | * file descriptors. | |
437 | */ | |
438 | ret = -1; | |
439 | errno = EBADF; | |
440 | } | |
441 | end: | |
442 | return ret; | |
443 | } |