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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> | |
1861a053 | 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) | |
50 | ||
51 | /* Check fd validity before calling these. */ | |
52 | #define ADD_FD_TO_SET(fd, fd_sets) \ | |
53 | FD_SET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
54 | #define IS_FD_SET(fd, fd_sets) \ | |
55 | FD_ISSET(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
56 | #define DEL_FD_FROM_SET(fd, fd_sets) \ | |
57 | FD_CLR(CALC_INDEX_TO_SET(fd), GET_FD_SET_FOR_FD(fd, fd_sets)) | |
58 | ||
59 | /* | |
60 | * Protect the lttng_fd_set. Nests within the ust_lock, and therefore | |
61 | * within the libc dl lock. Therefore, we need to fixup the TLS before | |
62 | * nesting into this lock. | |
63 | */ | |
64 | static pthread_mutex_t ust_safe_guard_fd_mutex = PTHREAD_MUTEX_INITIALIZER; | |
65 | /* | |
66 | * Track whether we are within lttng-ust or application, for close | |
67 | * system call override by LD_PRELOAD library. | |
68 | */ | |
69 | static DEFINE_URCU_TLS(int, thread_fd_tracking); | |
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; | |
1861a053 | 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 | { | |
82 | asm volatile ("" : : "m" (URCU_TLS(thread_fd_tracking))); | |
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 | ||
1861a053 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])); | |
1861a053 | 121 | CMM_STORE_SHARED(init_done, 1); |
6548fca4 MD |
122 | } |
123 | ||
124 | void lttng_ust_lock_fd_tracker(void) | |
125 | { | |
126 | URCU_TLS(thread_fd_tracking) = 1; | |
127 | /* | |
128 | * Ensure the compiler don't move the store after the close() | |
129 | * call in case close() would be marked as leaf. | |
130 | */ | |
131 | cmm_barrier(); | |
132 | pthread_mutex_lock(&ust_safe_guard_fd_mutex); | |
133 | } | |
134 | ||
135 | void lttng_ust_unlock_fd_tracker(void) | |
136 | { | |
137 | pthread_mutex_unlock(&ust_safe_guard_fd_mutex); | |
138 | /* | |
139 | * Ensure the compiler don't move the store before the close() | |
140 | * call, in case close() would be marked as leaf. | |
141 | */ | |
142 | cmm_barrier(); | |
143 | URCU_TLS(thread_fd_tracking) = 0; | |
144 | } | |
145 | ||
146 | /* | |
147 | * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd. | |
148 | * Has strict checking of fd validity. | |
149 | */ | |
150 | void lttng_ust_add_fd_to_tracker(int fd) | |
151 | { | |
1861a053 MD |
152 | /* |
153 | * Ensure the tracker is initialized when called from | |
154 | * constructors. | |
155 | */ | |
156 | lttng_ust_init_fd_tracker(); | |
157 | ||
6548fca4 MD |
158 | assert(URCU_TLS(thread_fd_tracking)); |
159 | /* Trying to add an fd which we can not accommodate. */ | |
160 | assert(IS_FD_VALID(fd)); | |
161 | /* Setting an fd thats already set. */ | |
162 | assert(!IS_FD_SET(fd, lttng_fd_set)); | |
163 | ||
164 | ADD_FD_TO_SET(fd, lttng_fd_set); | |
165 | } | |
166 | ||
167 | /* | |
168 | * Needs to be called with ust_safe_guard_fd_mutex held when opening the fd. | |
169 | * Has strict checking for fd validity. | |
170 | */ | |
171 | void lttng_ust_delete_fd_from_tracker(int fd) | |
172 | { | |
1861a053 MD |
173 | /* |
174 | * Ensure the tracker is initialized when called from | |
175 | * constructors. | |
176 | */ | |
177 | lttng_ust_init_fd_tracker(); | |
178 | ||
6548fca4 MD |
179 | assert(URCU_TLS(thread_fd_tracking)); |
180 | /* Not a valid fd. */ | |
181 | assert(IS_FD_VALID(fd)); | |
182 | /* Deleting an fd which was not set. */ | |
183 | assert(IS_FD_SET(fd, lttng_fd_set)); | |
184 | ||
185 | DEL_FD_FROM_SET(fd, lttng_fd_set); | |
186 | } | |
187 | ||
188 | /* | |
189 | * Interface allowing applications to close arbitrary file descriptors. | |
190 | * We check if it is owned by lttng-ust, and return -1, errno=EBADF | |
191 | * instead of closing it if it is the case. | |
192 | */ | |
193 | int lttng_ust_safe_close_fd(int fd, int (*close_cb)(int fd)) | |
194 | { | |
195 | int ret = 0; | |
196 | ||
197 | lttng_ust_fixup_fd_tracker_tls(); | |
198 | ||
1861a053 MD |
199 | /* |
200 | * Ensure the tracker is initialized when called from | |
201 | * constructors. | |
202 | */ | |
203 | lttng_ust_init_fd_tracker(); | |
204 | ||
6548fca4 MD |
205 | /* |
206 | * If called from lttng-ust, we directly call close without | |
207 | * validating whether the FD is part of the tracked set. | |
208 | */ | |
209 | if (URCU_TLS(thread_fd_tracking)) | |
210 | return close_cb(fd); | |
211 | ||
212 | lttng_ust_lock_fd_tracker(); | |
213 | if (IS_FD_VALID(fd) && IS_FD_SET(fd, lttng_fd_set)) { | |
214 | ret = -1; | |
215 | errno = EBADF; | |
216 | } else { | |
217 | ret = close_cb(fd); | |
218 | } | |
219 | lttng_ust_unlock_fd_tracker(); | |
220 | ||
221 | return ret; | |
222 | } | |
223 | ||
23948cd7 MD |
224 | /* |
225 | * Interface allowing applications to close arbitrary streams. | |
226 | * We check if it is owned by lttng-ust, and return -1, errno=EBADF | |
227 | * instead of closing it if it is the case. | |
228 | */ | |
229 | int lttng_ust_safe_fclose_stream(FILE *stream, int (*fclose_cb)(FILE *stream)) | |
230 | { | |
231 | int ret = 0, fd; | |
232 | ||
233 | lttng_ust_fixup_fd_tracker_tls(); | |
234 | ||
1861a053 MD |
235 | /* |
236 | * Ensure the tracker is initialized when called from | |
237 | * constructors. | |
238 | */ | |
239 | lttng_ust_init_fd_tracker(); | |
240 | ||
23948cd7 MD |
241 | /* |
242 | * If called from lttng-ust, we directly call fclose without | |
243 | * validating whether the FD is part of the tracked set. | |
244 | */ | |
245 | if (URCU_TLS(thread_fd_tracking)) | |
246 | return fclose_cb(stream); | |
247 | ||
248 | fd = fileno(stream); | |
249 | ||
250 | lttng_ust_lock_fd_tracker(); | |
251 | if (IS_FD_VALID(fd) && IS_FD_SET(fd, lttng_fd_set)) { | |
252 | ret = -1; | |
253 | errno = EBADF; | |
254 | } else { | |
255 | ret = fclose_cb(stream); | |
256 | } | |
257 | lttng_ust_unlock_fd_tracker(); | |
258 | ||
259 | return ret; | |
260 | } | |
261 | ||
6548fca4 MD |
262 | #ifdef __OpenBSD__ |
263 | static void set_close_success(int *p) | |
264 | { | |
265 | *p = 1; | |
266 | } | |
267 | static int test_close_success(const int *p) | |
268 | { | |
269 | return *p; | |
270 | } | |
271 | #else | |
272 | static void set_close_success(int *p __attribute__((unused))) | |
273 | { | |
274 | } | |
275 | static int test_close_success(const int *p __attribute__((unused))) | |
276 | { | |
277 | return 1; | |
278 | } | |
279 | #endif | |
280 | ||
281 | /* | |
282 | * Implement helper for closefrom() override. | |
283 | */ | |
284 | int lttng_ust_safe_closefrom_fd(int lowfd, int (*close_cb)(int fd)) | |
285 | { | |
286 | int ret = 0, close_success = 0, i; | |
287 | ||
288 | lttng_ust_fixup_fd_tracker_tls(); | |
289 | ||
1861a053 MD |
290 | /* |
291 | * Ensure the tracker is initialized when called from | |
292 | * constructors. | |
293 | */ | |
294 | lttng_ust_init_fd_tracker(); | |
295 | ||
6548fca4 MD |
296 | if (lowfd < 0) { |
297 | /* | |
298 | * NetBSD return EBADF if fd is invalid. | |
299 | */ | |
300 | errno = EBADF; | |
301 | ret = -1; | |
302 | goto end; | |
303 | } | |
304 | /* | |
305 | * If called from lttng-ust, we directly call close without | |
306 | * validating whether the FD is part of the tracked set. | |
307 | */ | |
308 | if (URCU_TLS(thread_fd_tracking)) { | |
309 | for (i = lowfd; i < lttng_ust_max_fd; i++) { | |
310 | if (close_cb(i) < 0) { | |
311 | switch (errno) { | |
312 | case EBADF: | |
313 | continue; | |
314 | case EINTR: | |
315 | default: | |
316 | ret = -1; | |
317 | goto end; | |
318 | } | |
319 | } | |
320 | set_close_success(&close_success); | |
321 | } | |
322 | } else { | |
323 | lttng_ust_lock_fd_tracker(); | |
324 | for (i = lowfd; i < lttng_ust_max_fd; i++) { | |
325 | if (IS_FD_VALID(i) && IS_FD_SET(i, lttng_fd_set)) | |
326 | continue; | |
327 | if (close_cb(i) < 0) { | |
328 | switch (errno) { | |
329 | case EBADF: | |
330 | continue; | |
331 | case EINTR: | |
332 | default: | |
333 | ret = -1; | |
334 | lttng_ust_unlock_fd_tracker(); | |
335 | goto end; | |
336 | } | |
337 | } | |
338 | set_close_success(&close_success); | |
339 | } | |
340 | lttng_ust_unlock_fd_tracker(); | |
341 | } | |
342 | if (!test_close_success(&close_success)) { | |
343 | /* | |
344 | * OpenBSD return EBADF if fd is greater than all open | |
345 | * file descriptors. | |
346 | */ | |
347 | ret = -1; | |
348 | errno = EBADF; | |
349 | } | |
350 | end: | |
351 | return ret; | |
352 | } |