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1 | // SPDX-License-Identifier: GPL-2.0 | |
2 | /* | |
3 | * This file contains the procedures for the handling of select and poll | |
4 | * | |
5 | * Created for Linux based loosely upon Mathius Lattner's minix | |
6 | * patches by Peter MacDonald. Heavily edited by Linus. | |
7 | * | |
8 | * 4 February 1994 | |
9 | * COFF/ELF binary emulation. If the process has the STICKY_TIMEOUTS | |
10 | * flag set in its personality we do *not* modify the given timeout | |
11 | * parameter to reflect time remaining. | |
12 | * | |
13 | * 24 January 2000 | |
14 | * Changed sys_poll()/do_poll() to use PAGE_SIZE chunk-based allocation | |
15 | * of fds to overcome nfds < 16390 descriptors limit (Tigran Aivazian). | |
16 | */ | |
17 | ||
18 | #include <linux/kernel.h> | |
19 | #include <linux/sched/signal.h> | |
20 | #include <linux/sched/rt.h> | |
21 | #include <linux/syscalls.h> | |
22 | #include <linux/export.h> | |
23 | #include <linux/slab.h> | |
24 | #include <linux/poll.h> | |
25 | #include <linux/personality.h> /* for STICKY_TIMEOUTS */ | |
26 | #include <linux/file.h> | |
27 | #include <linux/fdtable.h> | |
28 | #include <linux/fs.h> | |
29 | #include <linux/rcupdate.h> | |
30 | #include <linux/hrtimer.h> | |
31 | #include <linux/freezer.h> | |
32 | #include <net/busy_poll.h> | |
33 | #include <linux/vmalloc.h> | |
34 | ||
35 | #include <linux/uaccess.h> | |
36 | ||
37 | ||
38 | /* | |
39 | * Estimate expected accuracy in ns from a timeval. | |
40 | * | |
41 | * After quite a bit of churning around, we've settled on | |
42 | * a simple thing of taking 0.1% of the timeout as the | |
43 | * slack, with a cap of 100 msec. | |
44 | * "nice" tasks get a 0.5% slack instead. | |
45 | * | |
46 | * Consider this comment an open invitation to come up with even | |
47 | * better solutions.. | |
48 | */ | |
49 | ||
50 | #define MAX_SLACK (100 * NSEC_PER_MSEC) | |
51 | ||
52 | static long __estimate_accuracy(struct timespec64 *tv) | |
53 | { | |
54 | long slack; | |
55 | int divfactor = 1000; | |
56 | ||
57 | if (tv->tv_sec < 0) | |
58 | return 0; | |
59 | ||
60 | if (task_nice(current) > 0) | |
61 | divfactor = divfactor / 5; | |
62 | ||
63 | if (tv->tv_sec > MAX_SLACK / (NSEC_PER_SEC/divfactor)) | |
64 | return MAX_SLACK; | |
65 | ||
66 | slack = tv->tv_nsec / divfactor; | |
67 | slack += tv->tv_sec * (NSEC_PER_SEC/divfactor); | |
68 | ||
69 | if (slack > MAX_SLACK) | |
70 | return MAX_SLACK; | |
71 | ||
72 | return slack; | |
73 | } | |
74 | ||
75 | u64 select_estimate_accuracy(struct timespec64 *tv) | |
76 | { | |
77 | u64 ret; | |
78 | struct timespec64 now; | |
79 | ||
80 | /* | |
81 | * Realtime tasks get a slack of 0 for obvious reasons. | |
82 | */ | |
83 | ||
84 | if (rt_task(current)) | |
85 | return 0; | |
86 | ||
87 | ktime_get_ts64(&now); | |
88 | now = timespec64_sub(*tv, now); | |
89 | ret = __estimate_accuracy(&now); | |
90 | if (ret < current->timer_slack_ns) | |
91 | return current->timer_slack_ns; | |
92 | return ret; | |
93 | } | |
94 | ||
95 | ||
96 | ||
97 | struct poll_table_page { | |
98 | struct poll_table_page * next; | |
99 | struct poll_table_entry * entry; | |
100 | struct poll_table_entry entries[0]; | |
101 | }; | |
102 | ||
103 | #define POLL_TABLE_FULL(table) \ | |
104 | ((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table)) | |
105 | ||
106 | /* | |
107 | * Ok, Peter made a complicated, but straightforward multiple_wait() function. | |
108 | * I have rewritten this, taking some shortcuts: This code may not be easy to | |
109 | * follow, but it should be free of race-conditions, and it's practical. If you | |
110 | * understand what I'm doing here, then you understand how the linux | |
111 | * sleep/wakeup mechanism works. | |
112 | * | |
113 | * Two very simple procedures, poll_wait() and poll_freewait() make all the | |
114 | * work. poll_wait() is an inline-function defined in <linux/poll.h>, | |
115 | * as all select/poll functions have to call it to add an entry to the | |
116 | * poll table. | |
117 | */ | |
118 | static void __pollwait(struct file *filp, wait_queue_head_t *wait_address, | |
119 | poll_table *p); | |
120 | ||
121 | void poll_initwait(struct poll_wqueues *pwq) | |
122 | { | |
123 | init_poll_funcptr(&pwq->pt, __pollwait); | |
124 | pwq->polling_task = current; | |
125 | pwq->triggered = 0; | |
126 | pwq->error = 0; | |
127 | pwq->table = NULL; | |
128 | pwq->inline_index = 0; | |
129 | } | |
130 | EXPORT_SYMBOL(poll_initwait); | |
131 | ||
132 | static void free_poll_entry(struct poll_table_entry *entry) | |
133 | { | |
134 | remove_wait_queue(entry->wait_address, &entry->wait); | |
135 | fput(entry->filp); | |
136 | } | |
137 | ||
138 | void poll_freewait(struct poll_wqueues *pwq) | |
139 | { | |
140 | struct poll_table_page * p = pwq->table; | |
141 | int i; | |
142 | for (i = 0; i < pwq->inline_index; i++) | |
143 | free_poll_entry(pwq->inline_entries + i); | |
144 | while (p) { | |
145 | struct poll_table_entry * entry; | |
146 | struct poll_table_page *old; | |
147 | ||
148 | entry = p->entry; | |
149 | do { | |
150 | entry--; | |
151 | free_poll_entry(entry); | |
152 | } while (entry > p->entries); | |
153 | old = p; | |
154 | p = p->next; | |
155 | free_page((unsigned long) old); | |
156 | } | |
157 | } | |
158 | EXPORT_SYMBOL(poll_freewait); | |
159 | ||
160 | static struct poll_table_entry *poll_get_entry(struct poll_wqueues *p) | |
161 | { | |
162 | struct poll_table_page *table = p->table; | |
163 | ||
164 | if (p->inline_index < N_INLINE_POLL_ENTRIES) | |
165 | return p->inline_entries + p->inline_index++; | |
166 | ||
167 | if (!table || POLL_TABLE_FULL(table)) { | |
168 | struct poll_table_page *new_table; | |
169 | ||
170 | new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL); | |
171 | if (!new_table) { | |
172 | p->error = -ENOMEM; | |
173 | return NULL; | |
174 | } | |
175 | new_table->entry = new_table->entries; | |
176 | new_table->next = table; | |
177 | p->table = new_table; | |
178 | table = new_table; | |
179 | } | |
180 | ||
181 | return table->entry++; | |
182 | } | |
183 | ||
184 | static int __pollwake(wait_queue_entry_t *wait, unsigned mode, int sync, void *key) | |
185 | { | |
186 | struct poll_wqueues *pwq = wait->private; | |
187 | DECLARE_WAITQUEUE(dummy_wait, pwq->polling_task); | |
188 | ||
189 | /* | |
190 | * Although this function is called under waitqueue lock, LOCK | |
191 | * doesn't imply write barrier and the users expect write | |
192 | * barrier semantics on wakeup functions. The following | |
193 | * smp_wmb() is equivalent to smp_wmb() in try_to_wake_up() | |
194 | * and is paired with smp_store_mb() in poll_schedule_timeout. | |
195 | */ | |
196 | smp_wmb(); | |
197 | pwq->triggered = 1; | |
198 | ||
199 | /* | |
200 | * Perform the default wake up operation using a dummy | |
201 | * waitqueue. | |
202 | * | |
203 | * TODO: This is hacky but there currently is no interface to | |
204 | * pass in @sync. @sync is scheduled to be removed and once | |
205 | * that happens, wake_up_process() can be used directly. | |
206 | */ | |
207 | return default_wake_function(&dummy_wait, mode, sync, key); | |
208 | } | |
209 | ||
210 | static int pollwake(wait_queue_entry_t *wait, unsigned mode, int sync, void *key) | |
211 | { | |
212 | struct poll_table_entry *entry; | |
213 | ||
214 | entry = container_of(wait, struct poll_table_entry, wait); | |
215 | if (key && !((unsigned long)key & entry->key)) | |
216 | return 0; | |
217 | return __pollwake(wait, mode, sync, key); | |
218 | } | |
219 | ||
220 | /* Add a new entry */ | |
221 | static void __pollwait(struct file *filp, wait_queue_head_t *wait_address, | |
222 | poll_table *p) | |
223 | { | |
224 | struct poll_wqueues *pwq = container_of(p, struct poll_wqueues, pt); | |
225 | struct poll_table_entry *entry = poll_get_entry(pwq); | |
226 | if (!entry) | |
227 | return; | |
228 | entry->filp = get_file(filp); | |
229 | entry->wait_address = wait_address; | |
230 | entry->key = p->_key; | |
231 | init_waitqueue_func_entry(&entry->wait, pollwake); | |
232 | entry->wait.private = pwq; | |
233 | add_wait_queue(wait_address, &entry->wait); | |
234 | } | |
235 | ||
236 | int poll_schedule_timeout(struct poll_wqueues *pwq, int state, | |
237 | ktime_t *expires, unsigned long slack) | |
238 | { | |
239 | int rc = -EINTR; | |
240 | ||
241 | set_current_state(state); | |
242 | if (!pwq->triggered) | |
243 | rc = schedule_hrtimeout_range(expires, slack, HRTIMER_MODE_ABS); | |
244 | __set_current_state(TASK_RUNNING); | |
245 | ||
246 | /* | |
247 | * Prepare for the next iteration. | |
248 | * | |
249 | * The following smp_store_mb() serves two purposes. First, it's | |
250 | * the counterpart rmb of the wmb in pollwake() such that data | |
251 | * written before wake up is always visible after wake up. | |
252 | * Second, the full barrier guarantees that triggered clearing | |
253 | * doesn't pass event check of the next iteration. Note that | |
254 | * this problem doesn't exist for the first iteration as | |
255 | * add_wait_queue() has full barrier semantics. | |
256 | */ | |
257 | smp_store_mb(pwq->triggered, 0); | |
258 | ||
259 | return rc; | |
260 | } | |
261 | EXPORT_SYMBOL(poll_schedule_timeout); | |
262 | ||
263 | /** | |
264 | * poll_select_set_timeout - helper function to setup the timeout value | |
265 | * @to: pointer to timespec64 variable for the final timeout | |
266 | * @sec: seconds (from user space) | |
267 | * @nsec: nanoseconds (from user space) | |
268 | * | |
269 | * Note, we do not use a timespec for the user space value here, That | |
270 | * way we can use the function for timeval and compat interfaces as well. | |
271 | * | |
272 | * Returns -EINVAL if sec/nsec are not normalized. Otherwise 0. | |
273 | */ | |
274 | int poll_select_set_timeout(struct timespec64 *to, time64_t sec, long nsec) | |
275 | { | |
276 | struct timespec64 ts = {.tv_sec = sec, .tv_nsec = nsec}; | |
277 | ||
278 | if (!timespec64_valid(&ts)) | |
279 | return -EINVAL; | |
280 | ||
281 | /* Optimize for the zero timeout value here */ | |
282 | if (!sec && !nsec) { | |
283 | to->tv_sec = to->tv_nsec = 0; | |
284 | } else { | |
285 | ktime_get_ts64(to); | |
286 | *to = timespec64_add_safe(*to, ts); | |
287 | } | |
288 | return 0; | |
289 | } | |
290 | ||
291 | static int poll_select_copy_remaining(struct timespec64 *end_time, | |
292 | void __user *p, | |
293 | int timeval, int ret) | |
294 | { | |
295 | struct timespec64 rts; | |
296 | struct timeval rtv; | |
297 | ||
298 | if (!p) | |
299 | return ret; | |
300 | ||
301 | if (current->personality & STICKY_TIMEOUTS) | |
302 | goto sticky; | |
303 | ||
304 | /* No update for zero timeout */ | |
305 | if (!end_time->tv_sec && !end_time->tv_nsec) | |
306 | return ret; | |
307 | ||
308 | ktime_get_ts64(&rts); | |
309 | rts = timespec64_sub(*end_time, rts); | |
310 | if (rts.tv_sec < 0) | |
311 | rts.tv_sec = rts.tv_nsec = 0; | |
312 | ||
313 | ||
314 | if (timeval) { | |
315 | if (sizeof(rtv) > sizeof(rtv.tv_sec) + sizeof(rtv.tv_usec)) | |
316 | memset(&rtv, 0, sizeof(rtv)); | |
317 | rtv.tv_sec = rts.tv_sec; | |
318 | rtv.tv_usec = rts.tv_nsec / NSEC_PER_USEC; | |
319 | ||
320 | if (!copy_to_user(p, &rtv, sizeof(rtv))) | |
321 | return ret; | |
322 | ||
323 | } else if (!put_timespec64(&rts, p)) | |
324 | return ret; | |
325 | ||
326 | /* | |
327 | * If an application puts its timeval in read-only memory, we | |
328 | * don't want the Linux-specific update to the timeval to | |
329 | * cause a fault after the select has completed | |
330 | * successfully. However, because we're not updating the | |
331 | * timeval, we can't restart the system call. | |
332 | */ | |
333 | ||
334 | sticky: | |
335 | if (ret == -ERESTARTNOHAND) | |
336 | ret = -EINTR; | |
337 | return ret; | |
338 | } | |
339 | ||
340 | /* | |
341 | * Scalable version of the fd_set. | |
342 | */ | |
343 | ||
344 | typedef struct { | |
345 | unsigned long *in, *out, *ex; | |
346 | unsigned long *res_in, *res_out, *res_ex; | |
347 | } fd_set_bits; | |
348 | ||
349 | /* | |
350 | * How many longwords for "nr" bits? | |
351 | */ | |
352 | #define FDS_BITPERLONG (8*sizeof(long)) | |
353 | #define FDS_LONGS(nr) (((nr)+FDS_BITPERLONG-1)/FDS_BITPERLONG) | |
354 | #define FDS_BYTES(nr) (FDS_LONGS(nr)*sizeof(long)) | |
355 | ||
356 | /* | |
357 | * We do a VERIFY_WRITE here even though we are only reading this time: | |
358 | * we'll write to it eventually.. | |
359 | * | |
360 | * Use "unsigned long" accesses to let user-mode fd_set's be long-aligned. | |
361 | */ | |
362 | static inline | |
363 | int get_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset) | |
364 | { | |
365 | nr = FDS_BYTES(nr); | |
366 | if (ufdset) | |
367 | return copy_from_user(fdset, ufdset, nr) ? -EFAULT : 0; | |
368 | ||
369 | memset(fdset, 0, nr); | |
370 | return 0; | |
371 | } | |
372 | ||
373 | static inline unsigned long __must_check | |
374 | set_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset) | |
375 | { | |
376 | if (ufdset) | |
377 | return __copy_to_user(ufdset, fdset, FDS_BYTES(nr)); | |
378 | return 0; | |
379 | } | |
380 | ||
381 | static inline | |
382 | void zero_fd_set(unsigned long nr, unsigned long *fdset) | |
383 | { | |
384 | memset(fdset, 0, FDS_BYTES(nr)); | |
385 | } | |
386 | ||
387 | #define FDS_IN(fds, n) (fds->in + n) | |
388 | #define FDS_OUT(fds, n) (fds->out + n) | |
389 | #define FDS_EX(fds, n) (fds->ex + n) | |
390 | ||
391 | #define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n)) | |
392 | ||
393 | static int max_select_fd(unsigned long n, fd_set_bits *fds) | |
394 | { | |
395 | unsigned long *open_fds; | |
396 | unsigned long set; | |
397 | int max; | |
398 | struct fdtable *fdt; | |
399 | ||
400 | /* handle last in-complete long-word first */ | |
401 | set = ~(~0UL << (n & (BITS_PER_LONG-1))); | |
402 | n /= BITS_PER_LONG; | |
403 | fdt = files_fdtable(current->files); | |
404 | open_fds = fdt->open_fds + n; | |
405 | max = 0; | |
406 | if (set) { | |
407 | set &= BITS(fds, n); | |
408 | if (set) { | |
409 | if (!(set & ~*open_fds)) | |
410 | goto get_max; | |
411 | return -EBADF; | |
412 | } | |
413 | } | |
414 | while (n) { | |
415 | open_fds--; | |
416 | n--; | |
417 | set = BITS(fds, n); | |
418 | if (!set) | |
419 | continue; | |
420 | if (set & ~*open_fds) | |
421 | return -EBADF; | |
422 | if (max) | |
423 | continue; | |
424 | get_max: | |
425 | do { | |
426 | max++; | |
427 | set >>= 1; | |
428 | } while (set); | |
429 | max += n * BITS_PER_LONG; | |
430 | } | |
431 | ||
432 | return max; | |
433 | } | |
434 | ||
435 | #define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP | POLLERR) | |
436 | #define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR) | |
437 | #define POLLEX_SET (POLLPRI) | |
438 | ||
439 | static inline void wait_key_set(poll_table *wait, unsigned long in, | |
440 | unsigned long out, unsigned long bit, | |
441 | unsigned int ll_flag) | |
442 | { | |
443 | wait->_key = POLLEX_SET | ll_flag; | |
444 | if (in & bit) | |
445 | wait->_key |= POLLIN_SET; | |
446 | if (out & bit) | |
447 | wait->_key |= POLLOUT_SET; | |
448 | } | |
449 | ||
450 | static int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time) | |
451 | { | |
452 | ktime_t expire, *to = NULL; | |
453 | struct poll_wqueues table; | |
454 | poll_table *wait; | |
455 | int retval, i, timed_out = 0; | |
456 | u64 slack = 0; | |
457 | unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0; | |
458 | unsigned long busy_start = 0; | |
459 | ||
460 | rcu_read_lock(); | |
461 | retval = max_select_fd(n, fds); | |
462 | rcu_read_unlock(); | |
463 | ||
464 | if (retval < 0) | |
465 | return retval; | |
466 | n = retval; | |
467 | ||
468 | poll_initwait(&table); | |
469 | wait = &table.pt; | |
470 | if (end_time && !end_time->tv_sec && !end_time->tv_nsec) { | |
471 | wait->_qproc = NULL; | |
472 | timed_out = 1; | |
473 | } | |
474 | ||
475 | if (end_time && !timed_out) | |
476 | slack = select_estimate_accuracy(end_time); | |
477 | ||
478 | retval = 0; | |
479 | for (;;) { | |
480 | unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp; | |
481 | bool can_busy_loop = false; | |
482 | ||
483 | inp = fds->in; outp = fds->out; exp = fds->ex; | |
484 | rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex; | |
485 | ||
486 | for (i = 0; i < n; ++rinp, ++routp, ++rexp) { | |
487 | unsigned long in, out, ex, all_bits, bit = 1, mask, j; | |
488 | unsigned long res_in = 0, res_out = 0, res_ex = 0; | |
489 | ||
490 | in = *inp++; out = *outp++; ex = *exp++; | |
491 | all_bits = in | out | ex; | |
492 | if (all_bits == 0) { | |
493 | i += BITS_PER_LONG; | |
494 | continue; | |
495 | } | |
496 | ||
497 | for (j = 0; j < BITS_PER_LONG; ++j, ++i, bit <<= 1) { | |
498 | struct fd f; | |
499 | if (i >= n) | |
500 | break; | |
501 | if (!(bit & all_bits)) | |
502 | continue; | |
503 | f = fdget(i); | |
504 | if (f.file) { | |
505 | const struct file_operations *f_op; | |
506 | f_op = f.file->f_op; | |
507 | mask = DEFAULT_POLLMASK; | |
508 | if (f_op->poll) { | |
509 | wait_key_set(wait, in, out, | |
510 | bit, busy_flag); | |
511 | mask = (*f_op->poll)(f.file, wait); | |
512 | } | |
513 | fdput(f); | |
514 | if ((mask & POLLIN_SET) && (in & bit)) { | |
515 | res_in |= bit; | |
516 | retval++; | |
517 | wait->_qproc = NULL; | |
518 | } | |
519 | if ((mask & POLLOUT_SET) && (out & bit)) { | |
520 | res_out |= bit; | |
521 | retval++; | |
522 | wait->_qproc = NULL; | |
523 | } | |
524 | if ((mask & POLLEX_SET) && (ex & bit)) { | |
525 | res_ex |= bit; | |
526 | retval++; | |
527 | wait->_qproc = NULL; | |
528 | } | |
529 | /* got something, stop busy polling */ | |
530 | if (retval) { | |
531 | can_busy_loop = false; | |
532 | busy_flag = 0; | |
533 | ||
534 | /* | |
535 | * only remember a returned | |
536 | * POLL_BUSY_LOOP if we asked for it | |
537 | */ | |
538 | } else if (busy_flag & mask) | |
539 | can_busy_loop = true; | |
540 | ||
541 | } | |
542 | } | |
543 | if (res_in) | |
544 | *rinp = res_in; | |
545 | if (res_out) | |
546 | *routp = res_out; | |
547 | if (res_ex) | |
548 | *rexp = res_ex; | |
549 | cond_resched(); | |
550 | } | |
551 | wait->_qproc = NULL; | |
552 | if (retval || timed_out || signal_pending(current)) | |
553 | break; | |
554 | if (table.error) { | |
555 | retval = table.error; | |
556 | break; | |
557 | } | |
558 | ||
559 | /* only if found POLL_BUSY_LOOP sockets && not out of time */ | |
560 | if (can_busy_loop && !need_resched()) { | |
561 | if (!busy_start) { | |
562 | busy_start = busy_loop_current_time(); | |
563 | continue; | |
564 | } | |
565 | if (!busy_loop_timeout(busy_start)) | |
566 | continue; | |
567 | } | |
568 | busy_flag = 0; | |
569 | ||
570 | /* | |
571 | * If this is the first loop and we have a timeout | |
572 | * given, then we convert to ktime_t and set the to | |
573 | * pointer to the expiry value. | |
574 | */ | |
575 | if (end_time && !to) { | |
576 | expire = timespec64_to_ktime(*end_time); | |
577 | to = &expire; | |
578 | } | |
579 | ||
580 | if (!poll_schedule_timeout(&table, TASK_INTERRUPTIBLE, | |
581 | to, slack)) | |
582 | timed_out = 1; | |
583 | } | |
584 | ||
585 | poll_freewait(&table); | |
586 | ||
587 | return retval; | |
588 | } | |
589 | ||
590 | /* | |
591 | * We can actually return ERESTARTSYS instead of EINTR, but I'd | |
592 | * like to be certain this leads to no problems. So I return | |
593 | * EINTR just for safety. | |
594 | * | |
595 | * Update: ERESTARTSYS breaks at least the xview clock binary, so | |
596 | * I'm trying ERESTARTNOHAND which restart only when you want to. | |
597 | */ | |
598 | int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp, | |
599 | fd_set __user *exp, struct timespec64 *end_time) | |
600 | { | |
601 | fd_set_bits fds; | |
602 | void *bits; | |
603 | int ret, max_fds; | |
604 | size_t size, alloc_size; | |
605 | struct fdtable *fdt; | |
606 | /* Allocate small arguments on the stack to save memory and be faster */ | |
607 | long stack_fds[SELECT_STACK_ALLOC/sizeof(long)]; | |
608 | ||
609 | ret = -EINVAL; | |
610 | if (n < 0) | |
611 | goto out_nofds; | |
612 | ||
613 | /* max_fds can increase, so grab it once to avoid race */ | |
614 | rcu_read_lock(); | |
615 | fdt = files_fdtable(current->files); | |
616 | max_fds = fdt->max_fds; | |
617 | rcu_read_unlock(); | |
618 | if (n > max_fds) | |
619 | n = max_fds; | |
620 | ||
621 | /* | |
622 | * We need 6 bitmaps (in/out/ex for both incoming and outgoing), | |
623 | * since we used fdset we need to allocate memory in units of | |
624 | * long-words. | |
625 | */ | |
626 | size = FDS_BYTES(n); | |
627 | bits = stack_fds; | |
628 | if (size > sizeof(stack_fds) / 6) { | |
629 | /* Not enough space in on-stack array; must use kmalloc */ | |
630 | ret = -ENOMEM; | |
631 | if (size > (SIZE_MAX / 6)) | |
632 | goto out_nofds; | |
633 | ||
634 | alloc_size = 6 * size; | |
635 | bits = kvmalloc(alloc_size, GFP_KERNEL); | |
636 | if (!bits) | |
637 | goto out_nofds; | |
638 | } | |
639 | fds.in = bits; | |
640 | fds.out = bits + size; | |
641 | fds.ex = bits + 2*size; | |
642 | fds.res_in = bits + 3*size; | |
643 | fds.res_out = bits + 4*size; | |
644 | fds.res_ex = bits + 5*size; | |
645 | ||
646 | if ((ret = get_fd_set(n, inp, fds.in)) || | |
647 | (ret = get_fd_set(n, outp, fds.out)) || | |
648 | (ret = get_fd_set(n, exp, fds.ex))) | |
649 | goto out; | |
650 | zero_fd_set(n, fds.res_in); | |
651 | zero_fd_set(n, fds.res_out); | |
652 | zero_fd_set(n, fds.res_ex); | |
653 | ||
654 | ret = do_select(n, &fds, end_time); | |
655 | ||
656 | if (ret < 0) | |
657 | goto out; | |
658 | if (!ret) { | |
659 | ret = -ERESTARTNOHAND; | |
660 | if (signal_pending(current)) | |
661 | goto out; | |
662 | ret = 0; | |
663 | } | |
664 | ||
665 | if (set_fd_set(n, inp, fds.res_in) || | |
666 | set_fd_set(n, outp, fds.res_out) || | |
667 | set_fd_set(n, exp, fds.res_ex)) | |
668 | ret = -EFAULT; | |
669 | ||
670 | out: | |
671 | if (bits != stack_fds) | |
672 | kvfree(bits); | |
673 | out_nofds: | |
674 | return ret; | |
675 | } | |
676 | ||
677 | SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp, | |
678 | fd_set __user *, exp, struct timeval __user *, tvp) | |
679 | { | |
680 | struct timespec64 end_time, *to = NULL; | |
681 | struct timeval tv; | |
682 | int ret; | |
683 | ||
684 | if (tvp) { | |
685 | if (copy_from_user(&tv, tvp, sizeof(tv))) | |
686 | return -EFAULT; | |
687 | ||
688 | to = &end_time; | |
689 | if (poll_select_set_timeout(to, | |
690 | tv.tv_sec + (tv.tv_usec / USEC_PER_SEC), | |
691 | (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC)) | |
692 | return -EINVAL; | |
693 | } | |
694 | ||
695 | ret = core_sys_select(n, inp, outp, exp, to); | |
696 | ret = poll_select_copy_remaining(&end_time, tvp, 1, ret); | |
697 | ||
698 | return ret; | |
699 | } | |
700 | ||
701 | static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp, | |
702 | fd_set __user *exp, struct timespec __user *tsp, | |
703 | const sigset_t __user *sigmask, size_t sigsetsize) | |
704 | { | |
705 | sigset_t ksigmask, sigsaved; | |
706 | struct timespec64 ts, end_time, *to = NULL; | |
707 | int ret; | |
708 | ||
709 | if (tsp) { | |
710 | if (get_timespec64(&ts, tsp)) | |
711 | return -EFAULT; | |
712 | ||
713 | to = &end_time; | |
714 | if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec)) | |
715 | return -EINVAL; | |
716 | } | |
717 | ||
718 | if (sigmask) { | |
719 | /* XXX: Don't preclude handling different sized sigset_t's. */ | |
720 | if (sigsetsize != sizeof(sigset_t)) | |
721 | return -EINVAL; | |
722 | if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) | |
723 | return -EFAULT; | |
724 | ||
725 | sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); | |
726 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); | |
727 | } | |
728 | ||
729 | ret = core_sys_select(n, inp, outp, exp, to); | |
730 | ret = poll_select_copy_remaining(&end_time, tsp, 0, ret); | |
731 | ||
732 | if (ret == -ERESTARTNOHAND) { | |
733 | /* | |
734 | * Don't restore the signal mask yet. Let do_signal() deliver | |
735 | * the signal on the way back to userspace, before the signal | |
736 | * mask is restored. | |
737 | */ | |
738 | if (sigmask) { | |
739 | memcpy(¤t->saved_sigmask, &sigsaved, | |
740 | sizeof(sigsaved)); | |
741 | set_restore_sigmask(); | |
742 | } | |
743 | } else if (sigmask) | |
744 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); | |
745 | ||
746 | return ret; | |
747 | } | |
748 | ||
749 | /* | |
750 | * Most architectures can't handle 7-argument syscalls. So we provide a | |
751 | * 6-argument version where the sixth argument is a pointer to a structure | |
752 | * which has a pointer to the sigset_t itself followed by a size_t containing | |
753 | * the sigset size. | |
754 | */ | |
755 | SYSCALL_DEFINE6(pselect6, int, n, fd_set __user *, inp, fd_set __user *, outp, | |
756 | fd_set __user *, exp, struct timespec __user *, tsp, | |
757 | void __user *, sig) | |
758 | { | |
759 | size_t sigsetsize = 0; | |
760 | sigset_t __user *up = NULL; | |
761 | ||
762 | if (sig) { | |
763 | if (!access_ok(VERIFY_READ, sig, sizeof(void *)+sizeof(size_t)) | |
764 | || __get_user(up, (sigset_t __user * __user *)sig) | |
765 | || __get_user(sigsetsize, | |
766 | (size_t __user *)(sig+sizeof(void *)))) | |
767 | return -EFAULT; | |
768 | } | |
769 | ||
770 | return do_pselect(n, inp, outp, exp, tsp, up, sigsetsize); | |
771 | } | |
772 | ||
773 | #ifdef __ARCH_WANT_SYS_OLD_SELECT | |
774 | struct sel_arg_struct { | |
775 | unsigned long n; | |
776 | fd_set __user *inp, *outp, *exp; | |
777 | struct timeval __user *tvp; | |
778 | }; | |
779 | ||
780 | SYSCALL_DEFINE1(old_select, struct sel_arg_struct __user *, arg) | |
781 | { | |
782 | struct sel_arg_struct a; | |
783 | ||
784 | if (copy_from_user(&a, arg, sizeof(a))) | |
785 | return -EFAULT; | |
786 | return sys_select(a.n, a.inp, a.outp, a.exp, a.tvp); | |
787 | } | |
788 | #endif | |
789 | ||
790 | struct poll_list { | |
791 | struct poll_list *next; | |
792 | int len; | |
793 | struct pollfd entries[0]; | |
794 | }; | |
795 | ||
796 | #define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd)) | |
797 | ||
798 | /* | |
799 | * Fish for pollable events on the pollfd->fd file descriptor. We're only | |
800 | * interested in events matching the pollfd->events mask, and the result | |
801 | * matching that mask is both recorded in pollfd->revents and returned. The | |
802 | * pwait poll_table will be used by the fd-provided poll handler for waiting, | |
803 | * if pwait->_qproc is non-NULL. | |
804 | */ | |
805 | static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait, | |
806 | bool *can_busy_poll, | |
807 | unsigned int busy_flag) | |
808 | { | |
809 | unsigned int mask; | |
810 | int fd; | |
811 | ||
812 | mask = 0; | |
813 | fd = pollfd->fd; | |
814 | if (fd >= 0) { | |
815 | struct fd f = fdget(fd); | |
816 | mask = POLLNVAL; | |
817 | if (f.file) { | |
818 | mask = DEFAULT_POLLMASK; | |
819 | if (f.file->f_op->poll) { | |
820 | pwait->_key = pollfd->events|POLLERR|POLLHUP; | |
821 | pwait->_key |= busy_flag; | |
822 | mask = f.file->f_op->poll(f.file, pwait); | |
823 | if (mask & busy_flag) | |
824 | *can_busy_poll = true; | |
825 | } | |
826 | /* Mask out unneeded events. */ | |
827 | mask &= pollfd->events | POLLERR | POLLHUP; | |
828 | fdput(f); | |
829 | } | |
830 | } | |
831 | pollfd->revents = mask; | |
832 | ||
833 | return mask; | |
834 | } | |
835 | ||
836 | static int do_poll(struct poll_list *list, struct poll_wqueues *wait, | |
837 | struct timespec64 *end_time) | |
838 | { | |
839 | poll_table* pt = &wait->pt; | |
840 | ktime_t expire, *to = NULL; | |
841 | int timed_out = 0, count = 0; | |
842 | u64 slack = 0; | |
843 | unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0; | |
844 | unsigned long busy_start = 0; | |
845 | ||
846 | /* Optimise the no-wait case */ | |
847 | if (end_time && !end_time->tv_sec && !end_time->tv_nsec) { | |
848 | pt->_qproc = NULL; | |
849 | timed_out = 1; | |
850 | } | |
851 | ||
852 | if (end_time && !timed_out) | |
853 | slack = select_estimate_accuracy(end_time); | |
854 | ||
855 | for (;;) { | |
856 | struct poll_list *walk; | |
857 | bool can_busy_loop = false; | |
858 | ||
859 | for (walk = list; walk != NULL; walk = walk->next) { | |
860 | struct pollfd * pfd, * pfd_end; | |
861 | ||
862 | pfd = walk->entries; | |
863 | pfd_end = pfd + walk->len; | |
864 | for (; pfd != pfd_end; pfd++) { | |
865 | /* | |
866 | * Fish for events. If we found one, record it | |
867 | * and kill poll_table->_qproc, so we don't | |
868 | * needlessly register any other waiters after | |
869 | * this. They'll get immediately deregistered | |
870 | * when we break out and return. | |
871 | */ | |
872 | if (do_pollfd(pfd, pt, &can_busy_loop, | |
873 | busy_flag)) { | |
874 | count++; | |
875 | pt->_qproc = NULL; | |
876 | /* found something, stop busy polling */ | |
877 | busy_flag = 0; | |
878 | can_busy_loop = false; | |
879 | } | |
880 | } | |
881 | } | |
882 | /* | |
883 | * All waiters have already been registered, so don't provide | |
884 | * a poll_table->_qproc to them on the next loop iteration. | |
885 | */ | |
886 | pt->_qproc = NULL; | |
887 | if (!count) { | |
888 | count = wait->error; | |
889 | if (signal_pending(current)) | |
890 | count = -EINTR; | |
891 | } | |
892 | if (count || timed_out) | |
893 | break; | |
894 | ||
895 | /* only if found POLL_BUSY_LOOP sockets && not out of time */ | |
896 | if (can_busy_loop && !need_resched()) { | |
897 | if (!busy_start) { | |
898 | busy_start = busy_loop_current_time(); | |
899 | continue; | |
900 | } | |
901 | if (!busy_loop_timeout(busy_start)) | |
902 | continue; | |
903 | } | |
904 | busy_flag = 0; | |
905 | ||
906 | /* | |
907 | * If this is the first loop and we have a timeout | |
908 | * given, then we convert to ktime_t and set the to | |
909 | * pointer to the expiry value. | |
910 | */ | |
911 | if (end_time && !to) { | |
912 | expire = timespec64_to_ktime(*end_time); | |
913 | to = &expire; | |
914 | } | |
915 | ||
916 | if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE, to, slack)) | |
917 | timed_out = 1; | |
918 | } | |
919 | return count; | |
920 | } | |
921 | ||
922 | #define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list)) / \ | |
923 | sizeof(struct pollfd)) | |
924 | ||
925 | static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, | |
926 | struct timespec64 *end_time) | |
927 | { | |
928 | struct poll_wqueues table; | |
929 | int err = -EFAULT, fdcount, len, size; | |
930 | /* Allocate small arguments on the stack to save memory and be | |
931 | faster - use long to make sure the buffer is aligned properly | |
932 | on 64 bit archs to avoid unaligned access */ | |
933 | long stack_pps[POLL_STACK_ALLOC/sizeof(long)]; | |
934 | struct poll_list *const head = (struct poll_list *)stack_pps; | |
935 | struct poll_list *walk = head; | |
936 | unsigned long todo = nfds; | |
937 | ||
938 | if (nfds > rlimit(RLIMIT_NOFILE)) | |
939 | return -EINVAL; | |
940 | ||
941 | len = min_t(unsigned int, nfds, N_STACK_PPS); | |
942 | for (;;) { | |
943 | walk->next = NULL; | |
944 | walk->len = len; | |
945 | if (!len) | |
946 | break; | |
947 | ||
948 | if (copy_from_user(walk->entries, ufds + nfds-todo, | |
949 | sizeof(struct pollfd) * walk->len)) | |
950 | goto out_fds; | |
951 | ||
952 | todo -= walk->len; | |
953 | if (!todo) | |
954 | break; | |
955 | ||
956 | len = min(todo, POLLFD_PER_PAGE); | |
957 | size = sizeof(struct poll_list) + sizeof(struct pollfd) * len; | |
958 | walk = walk->next = kmalloc(size, GFP_KERNEL); | |
959 | if (!walk) { | |
960 | err = -ENOMEM; | |
961 | goto out_fds; | |
962 | } | |
963 | } | |
964 | ||
965 | poll_initwait(&table); | |
966 | fdcount = do_poll(head, &table, end_time); | |
967 | poll_freewait(&table); | |
968 | ||
969 | for (walk = head; walk; walk = walk->next) { | |
970 | struct pollfd *fds = walk->entries; | |
971 | int j; | |
972 | ||
973 | for (j = 0; j < walk->len; j++, ufds++) | |
974 | if (__put_user(fds[j].revents, &ufds->revents)) | |
975 | goto out_fds; | |
976 | } | |
977 | ||
978 | err = fdcount; | |
979 | out_fds: | |
980 | walk = head->next; | |
981 | while (walk) { | |
982 | struct poll_list *pos = walk; | |
983 | walk = walk->next; | |
984 | kfree(pos); | |
985 | } | |
986 | ||
987 | return err; | |
988 | } | |
989 | ||
990 | static long do_restart_poll(struct restart_block *restart_block) | |
991 | { | |
992 | struct pollfd __user *ufds = restart_block->poll.ufds; | |
993 | int nfds = restart_block->poll.nfds; | |
994 | struct timespec64 *to = NULL, end_time; | |
995 | int ret; | |
996 | ||
997 | if (restart_block->poll.has_timeout) { | |
998 | end_time.tv_sec = restart_block->poll.tv_sec; | |
999 | end_time.tv_nsec = restart_block->poll.tv_nsec; | |
1000 | to = &end_time; | |
1001 | } | |
1002 | ||
1003 | ret = do_sys_poll(ufds, nfds, to); | |
1004 | ||
1005 | if (ret == -EINTR) { | |
1006 | restart_block->fn = do_restart_poll; | |
1007 | ret = -ERESTART_RESTARTBLOCK; | |
1008 | } | |
1009 | return ret; | |
1010 | } | |
1011 | ||
1012 | SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds, | |
1013 | int, timeout_msecs) | |
1014 | { | |
1015 | struct timespec64 end_time, *to = NULL; | |
1016 | int ret; | |
1017 | ||
1018 | if (timeout_msecs >= 0) { | |
1019 | to = &end_time; | |
1020 | poll_select_set_timeout(to, timeout_msecs / MSEC_PER_SEC, | |
1021 | NSEC_PER_MSEC * (timeout_msecs % MSEC_PER_SEC)); | |
1022 | } | |
1023 | ||
1024 | ret = do_sys_poll(ufds, nfds, to); | |
1025 | ||
1026 | if (ret == -EINTR) { | |
1027 | struct restart_block *restart_block; | |
1028 | ||
1029 | restart_block = ¤t->restart_block; | |
1030 | restart_block->fn = do_restart_poll; | |
1031 | restart_block->poll.ufds = ufds; | |
1032 | restart_block->poll.nfds = nfds; | |
1033 | ||
1034 | if (timeout_msecs >= 0) { | |
1035 | restart_block->poll.tv_sec = end_time.tv_sec; | |
1036 | restart_block->poll.tv_nsec = end_time.tv_nsec; | |
1037 | restart_block->poll.has_timeout = 1; | |
1038 | } else | |
1039 | restart_block->poll.has_timeout = 0; | |
1040 | ||
1041 | ret = -ERESTART_RESTARTBLOCK; | |
1042 | } | |
1043 | return ret; | |
1044 | } | |
1045 | ||
1046 | SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds, | |
1047 | struct timespec __user *, tsp, const sigset_t __user *, sigmask, | |
1048 | size_t, sigsetsize) | |
1049 | { | |
1050 | sigset_t ksigmask, sigsaved; | |
1051 | struct timespec64 ts, end_time, *to = NULL; | |
1052 | int ret; | |
1053 | ||
1054 | if (tsp) { | |
1055 | if (get_timespec64(&ts, tsp)) | |
1056 | return -EFAULT; | |
1057 | ||
1058 | to = &end_time; | |
1059 | if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec)) | |
1060 | return -EINVAL; | |
1061 | } | |
1062 | ||
1063 | if (sigmask) { | |
1064 | /* XXX: Don't preclude handling different sized sigset_t's. */ | |
1065 | if (sigsetsize != sizeof(sigset_t)) | |
1066 | return -EINVAL; | |
1067 | if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) | |
1068 | return -EFAULT; | |
1069 | ||
1070 | sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); | |
1071 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); | |
1072 | } | |
1073 | ||
1074 | ret = do_sys_poll(ufds, nfds, to); | |
1075 | ||
1076 | /* We can restart this syscall, usually */ | |
1077 | if (ret == -EINTR) { | |
1078 | /* | |
1079 | * Don't restore the signal mask yet. Let do_signal() deliver | |
1080 | * the signal on the way back to userspace, before the signal | |
1081 | * mask is restored. | |
1082 | */ | |
1083 | if (sigmask) { | |
1084 | memcpy(¤t->saved_sigmask, &sigsaved, | |
1085 | sizeof(sigsaved)); | |
1086 | set_restore_sigmask(); | |
1087 | } | |
1088 | ret = -ERESTARTNOHAND; | |
1089 | } else if (sigmask) | |
1090 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); | |
1091 | ||
1092 | ret = poll_select_copy_remaining(&end_time, tsp, 0, ret); | |
1093 | ||
1094 | return ret; | |
1095 | } | |
1096 | ||
1097 | #ifdef CONFIG_COMPAT | |
1098 | #define __COMPAT_NFDBITS (8 * sizeof(compat_ulong_t)) | |
1099 | ||
1100 | static | |
1101 | int compat_poll_select_copy_remaining(struct timespec64 *end_time, void __user *p, | |
1102 | int timeval, int ret) | |
1103 | { | |
1104 | struct timespec64 ts; | |
1105 | ||
1106 | if (!p) | |
1107 | return ret; | |
1108 | ||
1109 | if (current->personality & STICKY_TIMEOUTS) | |
1110 | goto sticky; | |
1111 | ||
1112 | /* No update for zero timeout */ | |
1113 | if (!end_time->tv_sec && !end_time->tv_nsec) | |
1114 | return ret; | |
1115 | ||
1116 | ktime_get_ts64(&ts); | |
1117 | ts = timespec64_sub(*end_time, ts); | |
1118 | if (ts.tv_sec < 0) | |
1119 | ts.tv_sec = ts.tv_nsec = 0; | |
1120 | ||
1121 | if (timeval) { | |
1122 | struct compat_timeval rtv; | |
1123 | ||
1124 | rtv.tv_sec = ts.tv_sec; | |
1125 | rtv.tv_usec = ts.tv_nsec / NSEC_PER_USEC; | |
1126 | ||
1127 | if (!copy_to_user(p, &rtv, sizeof(rtv))) | |
1128 | return ret; | |
1129 | } else { | |
1130 | if (!compat_put_timespec64(&ts, p)) | |
1131 | return ret; | |
1132 | } | |
1133 | /* | |
1134 | * If an application puts its timeval in read-only memory, we | |
1135 | * don't want the Linux-specific update to the timeval to | |
1136 | * cause a fault after the select has completed | |
1137 | * successfully. However, because we're not updating the | |
1138 | * timeval, we can't restart the system call. | |
1139 | */ | |
1140 | ||
1141 | sticky: | |
1142 | if (ret == -ERESTARTNOHAND) | |
1143 | ret = -EINTR; | |
1144 | return ret; | |
1145 | } | |
1146 | ||
1147 | /* | |
1148 | * Ooo, nasty. We need here to frob 32-bit unsigned longs to | |
1149 | * 64-bit unsigned longs. | |
1150 | */ | |
1151 | static | |
1152 | int compat_get_fd_set(unsigned long nr, compat_ulong_t __user *ufdset, | |
1153 | unsigned long *fdset) | |
1154 | { | |
1155 | if (ufdset) { | |
1156 | return compat_get_bitmap(fdset, ufdset, nr); | |
1157 | } else { | |
1158 | zero_fd_set(nr, fdset); | |
1159 | return 0; | |
1160 | } | |
1161 | } | |
1162 | ||
1163 | static | |
1164 | int compat_set_fd_set(unsigned long nr, compat_ulong_t __user *ufdset, | |
1165 | unsigned long *fdset) | |
1166 | { | |
1167 | if (!ufdset) | |
1168 | return 0; | |
1169 | return compat_put_bitmap(ufdset, fdset, nr); | |
1170 | } | |
1171 | ||
1172 | ||
1173 | /* | |
1174 | * This is a virtual copy of sys_select from fs/select.c and probably | |
1175 | * should be compared to it from time to time | |
1176 | */ | |
1177 | ||
1178 | /* | |
1179 | * We can actually return ERESTARTSYS instead of EINTR, but I'd | |
1180 | * like to be certain this leads to no problems. So I return | |
1181 | * EINTR just for safety. | |
1182 | * | |
1183 | * Update: ERESTARTSYS breaks at least the xview clock binary, so | |
1184 | * I'm trying ERESTARTNOHAND which restart only when you want to. | |
1185 | */ | |
1186 | static int compat_core_sys_select(int n, compat_ulong_t __user *inp, | |
1187 | compat_ulong_t __user *outp, compat_ulong_t __user *exp, | |
1188 | struct timespec64 *end_time) | |
1189 | { | |
1190 | fd_set_bits fds; | |
1191 | void *bits; | |
1192 | int size, max_fds, ret = -EINVAL; | |
1193 | struct fdtable *fdt; | |
1194 | long stack_fds[SELECT_STACK_ALLOC/sizeof(long)]; | |
1195 | ||
1196 | if (n < 0) | |
1197 | goto out_nofds; | |
1198 | ||
1199 | /* max_fds can increase, so grab it once to avoid race */ | |
1200 | rcu_read_lock(); | |
1201 | fdt = files_fdtable(current->files); | |
1202 | max_fds = fdt->max_fds; | |
1203 | rcu_read_unlock(); | |
1204 | if (n > max_fds) | |
1205 | n = max_fds; | |
1206 | ||
1207 | /* | |
1208 | * We need 6 bitmaps (in/out/ex for both incoming and outgoing), | |
1209 | * since we used fdset we need to allocate memory in units of | |
1210 | * long-words. | |
1211 | */ | |
1212 | size = FDS_BYTES(n); | |
1213 | bits = stack_fds; | |
1214 | if (size > sizeof(stack_fds) / 6) { | |
1215 | bits = kmalloc(6 * size, GFP_KERNEL); | |
1216 | ret = -ENOMEM; | |
1217 | if (!bits) | |
1218 | goto out_nofds; | |
1219 | } | |
1220 | fds.in = (unsigned long *) bits; | |
1221 | fds.out = (unsigned long *) (bits + size); | |
1222 | fds.ex = (unsigned long *) (bits + 2*size); | |
1223 | fds.res_in = (unsigned long *) (bits + 3*size); | |
1224 | fds.res_out = (unsigned long *) (bits + 4*size); | |
1225 | fds.res_ex = (unsigned long *) (bits + 5*size); | |
1226 | ||
1227 | if ((ret = compat_get_fd_set(n, inp, fds.in)) || | |
1228 | (ret = compat_get_fd_set(n, outp, fds.out)) || | |
1229 | (ret = compat_get_fd_set(n, exp, fds.ex))) | |
1230 | goto out; | |
1231 | zero_fd_set(n, fds.res_in); | |
1232 | zero_fd_set(n, fds.res_out); | |
1233 | zero_fd_set(n, fds.res_ex); | |
1234 | ||
1235 | ret = do_select(n, &fds, end_time); | |
1236 | ||
1237 | if (ret < 0) | |
1238 | goto out; | |
1239 | if (!ret) { | |
1240 | ret = -ERESTARTNOHAND; | |
1241 | if (signal_pending(current)) | |
1242 | goto out; | |
1243 | ret = 0; | |
1244 | } | |
1245 | ||
1246 | if (compat_set_fd_set(n, inp, fds.res_in) || | |
1247 | compat_set_fd_set(n, outp, fds.res_out) || | |
1248 | compat_set_fd_set(n, exp, fds.res_ex)) | |
1249 | ret = -EFAULT; | |
1250 | out: | |
1251 | if (bits != stack_fds) | |
1252 | kfree(bits); | |
1253 | out_nofds: | |
1254 | return ret; | |
1255 | } | |
1256 | ||
1257 | COMPAT_SYSCALL_DEFINE5(select, int, n, compat_ulong_t __user *, inp, | |
1258 | compat_ulong_t __user *, outp, compat_ulong_t __user *, exp, | |
1259 | struct compat_timeval __user *, tvp) | |
1260 | { | |
1261 | struct timespec64 end_time, *to = NULL; | |
1262 | struct compat_timeval tv; | |
1263 | int ret; | |
1264 | ||
1265 | if (tvp) { | |
1266 | if (copy_from_user(&tv, tvp, sizeof(tv))) | |
1267 | return -EFAULT; | |
1268 | ||
1269 | to = &end_time; | |
1270 | if (poll_select_set_timeout(to, | |
1271 | tv.tv_sec + (tv.tv_usec / USEC_PER_SEC), | |
1272 | (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC)) | |
1273 | return -EINVAL; | |
1274 | } | |
1275 | ||
1276 | ret = compat_core_sys_select(n, inp, outp, exp, to); | |
1277 | ret = compat_poll_select_copy_remaining(&end_time, tvp, 1, ret); | |
1278 | ||
1279 | return ret; | |
1280 | } | |
1281 | ||
1282 | struct compat_sel_arg_struct { | |
1283 | compat_ulong_t n; | |
1284 | compat_uptr_t inp; | |
1285 | compat_uptr_t outp; | |
1286 | compat_uptr_t exp; | |
1287 | compat_uptr_t tvp; | |
1288 | }; | |
1289 | ||
1290 | COMPAT_SYSCALL_DEFINE1(old_select, struct compat_sel_arg_struct __user *, arg) | |
1291 | { | |
1292 | struct compat_sel_arg_struct a; | |
1293 | ||
1294 | if (copy_from_user(&a, arg, sizeof(a))) | |
1295 | return -EFAULT; | |
1296 | return compat_sys_select(a.n, compat_ptr(a.inp), compat_ptr(a.outp), | |
1297 | compat_ptr(a.exp), compat_ptr(a.tvp)); | |
1298 | } | |
1299 | ||
1300 | static long do_compat_pselect(int n, compat_ulong_t __user *inp, | |
1301 | compat_ulong_t __user *outp, compat_ulong_t __user *exp, | |
1302 | struct compat_timespec __user *tsp, compat_sigset_t __user *sigmask, | |
1303 | compat_size_t sigsetsize) | |
1304 | { | |
1305 | sigset_t ksigmask, sigsaved; | |
1306 | struct timespec64 ts, end_time, *to = NULL; | |
1307 | int ret; | |
1308 | ||
1309 | if (tsp) { | |
1310 | if (compat_get_timespec64(&ts, tsp)) | |
1311 | return -EFAULT; | |
1312 | ||
1313 | to = &end_time; | |
1314 | if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec)) | |
1315 | return -EINVAL; | |
1316 | } | |
1317 | ||
1318 | if (sigmask) { | |
1319 | if (sigsetsize != sizeof(compat_sigset_t)) | |
1320 | return -EINVAL; | |
1321 | if (get_compat_sigset(&ksigmask, sigmask)) | |
1322 | return -EFAULT; | |
1323 | ||
1324 | sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); | |
1325 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); | |
1326 | } | |
1327 | ||
1328 | ret = compat_core_sys_select(n, inp, outp, exp, to); | |
1329 | ret = compat_poll_select_copy_remaining(&end_time, tsp, 0, ret); | |
1330 | ||
1331 | if (ret == -ERESTARTNOHAND) { | |
1332 | /* | |
1333 | * Don't restore the signal mask yet. Let do_signal() deliver | |
1334 | * the signal on the way back to userspace, before the signal | |
1335 | * mask is restored. | |
1336 | */ | |
1337 | if (sigmask) { | |
1338 | memcpy(¤t->saved_sigmask, &sigsaved, | |
1339 | sizeof(sigsaved)); | |
1340 | set_restore_sigmask(); | |
1341 | } | |
1342 | } else if (sigmask) | |
1343 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); | |
1344 | ||
1345 | return ret; | |
1346 | } | |
1347 | ||
1348 | COMPAT_SYSCALL_DEFINE6(pselect6, int, n, compat_ulong_t __user *, inp, | |
1349 | compat_ulong_t __user *, outp, compat_ulong_t __user *, exp, | |
1350 | struct compat_timespec __user *, tsp, void __user *, sig) | |
1351 | { | |
1352 | compat_size_t sigsetsize = 0; | |
1353 | compat_uptr_t up = 0; | |
1354 | ||
1355 | if (sig) { | |
1356 | if (!access_ok(VERIFY_READ, sig, | |
1357 | sizeof(compat_uptr_t)+sizeof(compat_size_t)) || | |
1358 | __get_user(up, (compat_uptr_t __user *)sig) || | |
1359 | __get_user(sigsetsize, | |
1360 | (compat_size_t __user *)(sig+sizeof(up)))) | |
1361 | return -EFAULT; | |
1362 | } | |
1363 | return do_compat_pselect(n, inp, outp, exp, tsp, compat_ptr(up), | |
1364 | sigsetsize); | |
1365 | } | |
1366 | ||
1367 | COMPAT_SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, | |
1368 | unsigned int, nfds, struct compat_timespec __user *, tsp, | |
1369 | const compat_sigset_t __user *, sigmask, compat_size_t, sigsetsize) | |
1370 | { | |
1371 | sigset_t ksigmask, sigsaved; | |
1372 | struct timespec64 ts, end_time, *to = NULL; | |
1373 | int ret; | |
1374 | ||
1375 | if (tsp) { | |
1376 | if (compat_get_timespec64(&ts, tsp)) | |
1377 | return -EFAULT; | |
1378 | ||
1379 | to = &end_time; | |
1380 | if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec)) | |
1381 | return -EINVAL; | |
1382 | } | |
1383 | ||
1384 | if (sigmask) { | |
1385 | if (sigsetsize != sizeof(compat_sigset_t)) | |
1386 | return -EINVAL; | |
1387 | if (get_compat_sigset(&ksigmask, sigmask)) | |
1388 | return -EFAULT; | |
1389 | ||
1390 | sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); | |
1391 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); | |
1392 | } | |
1393 | ||
1394 | ret = do_sys_poll(ufds, nfds, to); | |
1395 | ||
1396 | /* We can restart this syscall, usually */ | |
1397 | if (ret == -EINTR) { | |
1398 | /* | |
1399 | * Don't restore the signal mask yet. Let do_signal() deliver | |
1400 | * the signal on the way back to userspace, before the signal | |
1401 | * mask is restored. | |
1402 | */ | |
1403 | if (sigmask) { | |
1404 | memcpy(¤t->saved_sigmask, &sigsaved, | |
1405 | sizeof(sigsaved)); | |
1406 | set_restore_sigmask(); | |
1407 | } | |
1408 | ret = -ERESTARTNOHAND; | |
1409 | } else if (sigmask) | |
1410 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); | |
1411 | ||
1412 | ret = compat_poll_select_copy_remaining(&end_time, tsp, 0, ret); | |
1413 | ||
1414 | return ret; | |
1415 | } | |
1416 | #endif |