| 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 && !(key_to_poll(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 | static 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 | |
| 262 | /** |
| 263 | * poll_select_set_timeout - helper function to setup the timeout value |
| 264 | * @to: pointer to timespec64 variable for the final timeout |
| 265 | * @sec: seconds (from user space) |
| 266 | * @nsec: nanoseconds (from user space) |
| 267 | * |
| 268 | * Note, we do not use a timespec for the user space value here, That |
| 269 | * way we can use the function for timeval and compat interfaces as well. |
| 270 | * |
| 271 | * Returns -EINVAL if sec/nsec are not normalized. Otherwise 0. |
| 272 | */ |
| 273 | int poll_select_set_timeout(struct timespec64 *to, time64_t sec, long nsec) |
| 274 | { |
| 275 | struct timespec64 ts = {.tv_sec = sec, .tv_nsec = nsec}; |
| 276 | |
| 277 | if (!timespec64_valid(&ts)) |
| 278 | return -EINVAL; |
| 279 | |
| 280 | /* Optimize for the zero timeout value here */ |
| 281 | if (!sec && !nsec) { |
| 282 | to->tv_sec = to->tv_nsec = 0; |
| 283 | } else { |
| 284 | ktime_get_ts64(to); |
| 285 | *to = timespec64_add_safe(*to, ts); |
| 286 | } |
| 287 | return 0; |
| 288 | } |
| 289 | |
| 290 | static int poll_select_copy_remaining(struct timespec64 *end_time, |
| 291 | void __user *p, |
| 292 | int timeval, int ret) |
| 293 | { |
| 294 | struct timespec64 rts; |
| 295 | struct timeval rtv; |
| 296 | |
| 297 | if (!p) |
| 298 | return ret; |
| 299 | |
| 300 | if (current->personality & STICKY_TIMEOUTS) |
| 301 | goto sticky; |
| 302 | |
| 303 | /* No update for zero timeout */ |
| 304 | if (!end_time->tv_sec && !end_time->tv_nsec) |
| 305 | return ret; |
| 306 | |
| 307 | ktime_get_ts64(&rts); |
| 308 | rts = timespec64_sub(*end_time, rts); |
| 309 | if (rts.tv_sec < 0) |
| 310 | rts.tv_sec = rts.tv_nsec = 0; |
| 311 | |
| 312 | |
| 313 | if (timeval) { |
| 314 | if (sizeof(rtv) > sizeof(rtv.tv_sec) + sizeof(rtv.tv_usec)) |
| 315 | memset(&rtv, 0, sizeof(rtv)); |
| 316 | rtv.tv_sec = rts.tv_sec; |
| 317 | rtv.tv_usec = rts.tv_nsec / NSEC_PER_USEC; |
| 318 | |
| 319 | if (!copy_to_user(p, &rtv, sizeof(rtv))) |
| 320 | return ret; |
| 321 | |
| 322 | } else if (!put_timespec64(&rts, p)) |
| 323 | return ret; |
| 324 | |
| 325 | /* |
| 326 | * If an application puts its timeval in read-only memory, we |
| 327 | * don't want the Linux-specific update to the timeval to |
| 328 | * cause a fault after the select has completed |
| 329 | * successfully. However, because we're not updating the |
| 330 | * timeval, we can't restart the system call. |
| 331 | */ |
| 332 | |
| 333 | sticky: |
| 334 | if (ret == -ERESTARTNOHAND) |
| 335 | ret = -EINTR; |
| 336 | return ret; |
| 337 | } |
| 338 | |
| 339 | /* |
| 340 | * Scalable version of the fd_set. |
| 341 | */ |
| 342 | |
| 343 | typedef struct { |
| 344 | unsigned long *in, *out, *ex; |
| 345 | unsigned long *res_in, *res_out, *res_ex; |
| 346 | } fd_set_bits; |
| 347 | |
| 348 | /* |
| 349 | * How many longwords for "nr" bits? |
| 350 | */ |
| 351 | #define FDS_BITPERLONG (8*sizeof(long)) |
| 352 | #define FDS_LONGS(nr) (((nr)+FDS_BITPERLONG-1)/FDS_BITPERLONG) |
| 353 | #define FDS_BYTES(nr) (FDS_LONGS(nr)*sizeof(long)) |
| 354 | |
| 355 | /* |
| 356 | * We do a VERIFY_WRITE here even though we are only reading this time: |
| 357 | * we'll write to it eventually.. |
| 358 | * |
| 359 | * Use "unsigned long" accesses to let user-mode fd_set's be long-aligned. |
| 360 | */ |
| 361 | static inline |
| 362 | int get_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset) |
| 363 | { |
| 364 | nr = FDS_BYTES(nr); |
| 365 | if (ufdset) |
| 366 | return copy_from_user(fdset, ufdset, nr) ? -EFAULT : 0; |
| 367 | |
| 368 | memset(fdset, 0, nr); |
| 369 | return 0; |
| 370 | } |
| 371 | |
| 372 | static inline unsigned long __must_check |
| 373 | set_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset) |
| 374 | { |
| 375 | if (ufdset) |
| 376 | return __copy_to_user(ufdset, fdset, FDS_BYTES(nr)); |
| 377 | return 0; |
| 378 | } |
| 379 | |
| 380 | static inline |
| 381 | void zero_fd_set(unsigned long nr, unsigned long *fdset) |
| 382 | { |
| 383 | memset(fdset, 0, FDS_BYTES(nr)); |
| 384 | } |
| 385 | |
| 386 | #define FDS_IN(fds, n) (fds->in + n) |
| 387 | #define FDS_OUT(fds, n) (fds->out + n) |
| 388 | #define FDS_EX(fds, n) (fds->ex + n) |
| 389 | |
| 390 | #define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n)) |
| 391 | |
| 392 | static int max_select_fd(unsigned long n, fd_set_bits *fds) |
| 393 | { |
| 394 | unsigned long *open_fds; |
| 395 | unsigned long set; |
| 396 | int max; |
| 397 | struct fdtable *fdt; |
| 398 | |
| 399 | /* handle last in-complete long-word first */ |
| 400 | set = ~(~0UL << (n & (BITS_PER_LONG-1))); |
| 401 | n /= BITS_PER_LONG; |
| 402 | fdt = files_fdtable(current->files); |
| 403 | open_fds = fdt->open_fds + n; |
| 404 | max = 0; |
| 405 | if (set) { |
| 406 | set &= BITS(fds, n); |
| 407 | if (set) { |
| 408 | if (!(set & ~*open_fds)) |
| 409 | goto get_max; |
| 410 | return -EBADF; |
| 411 | } |
| 412 | } |
| 413 | while (n) { |
| 414 | open_fds--; |
| 415 | n--; |
| 416 | set = BITS(fds, n); |
| 417 | if (!set) |
| 418 | continue; |
| 419 | if (set & ~*open_fds) |
| 420 | return -EBADF; |
| 421 | if (max) |
| 422 | continue; |
| 423 | get_max: |
| 424 | do { |
| 425 | max++; |
| 426 | set >>= 1; |
| 427 | } while (set); |
| 428 | max += n * BITS_PER_LONG; |
| 429 | } |
| 430 | |
| 431 | return max; |
| 432 | } |
| 433 | |
| 434 | #define POLLIN_SET (EPOLLRDNORM | EPOLLRDBAND | EPOLLIN | EPOLLHUP | EPOLLERR) |
| 435 | #define POLLOUT_SET (EPOLLWRBAND | EPOLLWRNORM | EPOLLOUT | EPOLLERR) |
| 436 | #define POLLEX_SET (EPOLLPRI) |
| 437 | |
| 438 | static inline void wait_key_set(poll_table *wait, unsigned long in, |
| 439 | unsigned long out, unsigned long bit, |
| 440 | __poll_t ll_flag) |
| 441 | { |
| 442 | wait->_key = POLLEX_SET | ll_flag; |
| 443 | if (in & bit) |
| 444 | wait->_key |= POLLIN_SET; |
| 445 | if (out & bit) |
| 446 | wait->_key |= POLLOUT_SET; |
| 447 | } |
| 448 | |
| 449 | static int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time) |
| 450 | { |
| 451 | ktime_t expire, *to = NULL; |
| 452 | struct poll_wqueues table; |
| 453 | poll_table *wait; |
| 454 | int retval, i, timed_out = 0; |
| 455 | u64 slack = 0; |
| 456 | __poll_t busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0; |
| 457 | unsigned long busy_start = 0; |
| 458 | |
| 459 | rcu_read_lock(); |
| 460 | retval = max_select_fd(n, fds); |
| 461 | rcu_read_unlock(); |
| 462 | |
| 463 | if (retval < 0) |
| 464 | return retval; |
| 465 | n = retval; |
| 466 | |
| 467 | poll_initwait(&table); |
| 468 | wait = &table.pt; |
| 469 | if (end_time && !end_time->tv_sec && !end_time->tv_nsec) { |
| 470 | wait->_qproc = NULL; |
| 471 | timed_out = 1; |
| 472 | } |
| 473 | |
| 474 | if (end_time && !timed_out) |
| 475 | slack = select_estimate_accuracy(end_time); |
| 476 | |
| 477 | retval = 0; |
| 478 | for (;;) { |
| 479 | unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp; |
| 480 | bool can_busy_loop = false; |
| 481 | |
| 482 | inp = fds->in; outp = fds->out; exp = fds->ex; |
| 483 | rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex; |
| 484 | |
| 485 | for (i = 0; i < n; ++rinp, ++routp, ++rexp) { |
| 486 | unsigned long in, out, ex, all_bits, bit = 1, j; |
| 487 | unsigned long res_in = 0, res_out = 0, res_ex = 0; |
| 488 | __poll_t mask; |
| 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 | wait_key_set(wait, in, out, bit, |
| 506 | busy_flag); |
| 507 | mask = vfs_poll(f.file, wait); |
| 508 | |
| 509 | fdput(f); |
| 510 | if ((mask & POLLIN_SET) && (in & bit)) { |
| 511 | res_in |= bit; |
| 512 | retval++; |
| 513 | wait->_qproc = NULL; |
| 514 | } |
| 515 | if ((mask & POLLOUT_SET) && (out & bit)) { |
| 516 | res_out |= bit; |
| 517 | retval++; |
| 518 | wait->_qproc = NULL; |
| 519 | } |
| 520 | if ((mask & POLLEX_SET) && (ex & bit)) { |
| 521 | res_ex |= bit; |
| 522 | retval++; |
| 523 | wait->_qproc = NULL; |
| 524 | } |
| 525 | /* got something, stop busy polling */ |
| 526 | if (retval) { |
| 527 | can_busy_loop = false; |
| 528 | busy_flag = 0; |
| 529 | |
| 530 | /* |
| 531 | * only remember a returned |
| 532 | * POLL_BUSY_LOOP if we asked for it |
| 533 | */ |
| 534 | } else if (busy_flag & mask) |
| 535 | can_busy_loop = true; |
| 536 | |
| 537 | } |
| 538 | } |
| 539 | if (res_in) |
| 540 | *rinp = res_in; |
| 541 | if (res_out) |
| 542 | *routp = res_out; |
| 543 | if (res_ex) |
| 544 | *rexp = res_ex; |
| 545 | cond_resched(); |
| 546 | } |
| 547 | wait->_qproc = NULL; |
| 548 | if (retval || timed_out || signal_pending(current)) |
| 549 | break; |
| 550 | if (table.error) { |
| 551 | retval = table.error; |
| 552 | break; |
| 553 | } |
| 554 | |
| 555 | /* only if found POLL_BUSY_LOOP sockets && not out of time */ |
| 556 | if (can_busy_loop && !need_resched()) { |
| 557 | if (!busy_start) { |
| 558 | busy_start = busy_loop_current_time(); |
| 559 | continue; |
| 560 | } |
| 561 | if (!busy_loop_timeout(busy_start)) |
| 562 | continue; |
| 563 | } |
| 564 | busy_flag = 0; |
| 565 | |
| 566 | /* |
| 567 | * If this is the first loop and we have a timeout |
| 568 | * given, then we convert to ktime_t and set the to |
| 569 | * pointer to the expiry value. |
| 570 | */ |
| 571 | if (end_time && !to) { |
| 572 | expire = timespec64_to_ktime(*end_time); |
| 573 | to = &expire; |
| 574 | } |
| 575 | |
| 576 | if (!poll_schedule_timeout(&table, TASK_INTERRUPTIBLE, |
| 577 | to, slack)) |
| 578 | timed_out = 1; |
| 579 | } |
| 580 | |
| 581 | poll_freewait(&table); |
| 582 | |
| 583 | return retval; |
| 584 | } |
| 585 | |
| 586 | /* |
| 587 | * We can actually return ERESTARTSYS instead of EINTR, but I'd |
| 588 | * like to be certain this leads to no problems. So I return |
| 589 | * EINTR just for safety. |
| 590 | * |
| 591 | * Update: ERESTARTSYS breaks at least the xview clock binary, so |
| 592 | * I'm trying ERESTARTNOHAND which restart only when you want to. |
| 593 | */ |
| 594 | int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp, |
| 595 | fd_set __user *exp, struct timespec64 *end_time) |
| 596 | { |
| 597 | fd_set_bits fds; |
| 598 | void *bits; |
| 599 | int ret, max_fds; |
| 600 | size_t size, alloc_size; |
| 601 | struct fdtable *fdt; |
| 602 | /* Allocate small arguments on the stack to save memory and be faster */ |
| 603 | long stack_fds[SELECT_STACK_ALLOC/sizeof(long)]; |
| 604 | |
| 605 | ret = -EINVAL; |
| 606 | if (n < 0) |
| 607 | goto out_nofds; |
| 608 | |
| 609 | /* max_fds can increase, so grab it once to avoid race */ |
| 610 | rcu_read_lock(); |
| 611 | fdt = files_fdtable(current->files); |
| 612 | max_fds = fdt->max_fds; |
| 613 | rcu_read_unlock(); |
| 614 | if (n > max_fds) |
| 615 | n = max_fds; |
| 616 | |
| 617 | /* |
| 618 | * We need 6 bitmaps (in/out/ex for both incoming and outgoing), |
| 619 | * since we used fdset we need to allocate memory in units of |
| 620 | * long-words. |
| 621 | */ |
| 622 | size = FDS_BYTES(n); |
| 623 | bits = stack_fds; |
| 624 | if (size > sizeof(stack_fds) / 6) { |
| 625 | /* Not enough space in on-stack array; must use kmalloc */ |
| 626 | ret = -ENOMEM; |
| 627 | if (size > (SIZE_MAX / 6)) |
| 628 | goto out_nofds; |
| 629 | |
| 630 | alloc_size = 6 * size; |
| 631 | bits = kvmalloc(alloc_size, GFP_KERNEL); |
| 632 | if (!bits) |
| 633 | goto out_nofds; |
| 634 | } |
| 635 | fds.in = bits; |
| 636 | fds.out = bits + size; |
| 637 | fds.ex = bits + 2*size; |
| 638 | fds.res_in = bits + 3*size; |
| 639 | fds.res_out = bits + 4*size; |
| 640 | fds.res_ex = bits + 5*size; |
| 641 | |
| 642 | if ((ret = get_fd_set(n, inp, fds.in)) || |
| 643 | (ret = get_fd_set(n, outp, fds.out)) || |
| 644 | (ret = get_fd_set(n, exp, fds.ex))) |
| 645 | goto out; |
| 646 | zero_fd_set(n, fds.res_in); |
| 647 | zero_fd_set(n, fds.res_out); |
| 648 | zero_fd_set(n, fds.res_ex); |
| 649 | |
| 650 | ret = do_select(n, &fds, end_time); |
| 651 | |
| 652 | if (ret < 0) |
| 653 | goto out; |
| 654 | if (!ret) { |
| 655 | ret = -ERESTARTNOHAND; |
| 656 | if (signal_pending(current)) |
| 657 | goto out; |
| 658 | ret = 0; |
| 659 | } |
| 660 | |
| 661 | if (set_fd_set(n, inp, fds.res_in) || |
| 662 | set_fd_set(n, outp, fds.res_out) || |
| 663 | set_fd_set(n, exp, fds.res_ex)) |
| 664 | ret = -EFAULT; |
| 665 | |
| 666 | out: |
| 667 | if (bits != stack_fds) |
| 668 | kvfree(bits); |
| 669 | out_nofds: |
| 670 | return ret; |
| 671 | } |
| 672 | |
| 673 | static int kern_select(int n, fd_set __user *inp, fd_set __user *outp, |
| 674 | fd_set __user *exp, struct timeval __user *tvp) |
| 675 | { |
| 676 | struct timespec64 end_time, *to = NULL; |
| 677 | struct timeval tv; |
| 678 | int ret; |
| 679 | |
| 680 | if (tvp) { |
| 681 | if (copy_from_user(&tv, tvp, sizeof(tv))) |
| 682 | return -EFAULT; |
| 683 | |
| 684 | to = &end_time; |
| 685 | if (poll_select_set_timeout(to, |
| 686 | tv.tv_sec + (tv.tv_usec / USEC_PER_SEC), |
| 687 | (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC)) |
| 688 | return -EINVAL; |
| 689 | } |
| 690 | |
| 691 | ret = core_sys_select(n, inp, outp, exp, to); |
| 692 | ret = poll_select_copy_remaining(&end_time, tvp, 1, ret); |
| 693 | |
| 694 | return ret; |
| 695 | } |
| 696 | |
| 697 | SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp, |
| 698 | fd_set __user *, exp, struct timeval __user *, tvp) |
| 699 | { |
| 700 | return kern_select(n, inp, outp, exp, tvp); |
| 701 | } |
| 702 | |
| 703 | static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp, |
| 704 | fd_set __user *exp, struct timespec __user *tsp, |
| 705 | const sigset_t __user *sigmask, size_t sigsetsize) |
| 706 | { |
| 707 | sigset_t ksigmask, sigsaved; |
| 708 | struct timespec64 ts, end_time, *to = NULL; |
| 709 | int ret; |
| 710 | |
| 711 | if (tsp) { |
| 712 | if (get_timespec64(&ts, tsp)) |
| 713 | return -EFAULT; |
| 714 | |
| 715 | to = &end_time; |
| 716 | if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec)) |
| 717 | return -EINVAL; |
| 718 | } |
| 719 | |
| 720 | if (sigmask) { |
| 721 | /* XXX: Don't preclude handling different sized sigset_t's. */ |
| 722 | if (sigsetsize != sizeof(sigset_t)) |
| 723 | return -EINVAL; |
| 724 | if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) |
| 725 | return -EFAULT; |
| 726 | |
| 727 | sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); |
| 728 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); |
| 729 | } |
| 730 | |
| 731 | ret = core_sys_select(n, inp, outp, exp, to); |
| 732 | ret = poll_select_copy_remaining(&end_time, tsp, 0, ret); |
| 733 | |
| 734 | if (ret == -ERESTARTNOHAND) { |
| 735 | /* |
| 736 | * Don't restore the signal mask yet. Let do_signal() deliver |
| 737 | * the signal on the way back to userspace, before the signal |
| 738 | * mask is restored. |
| 739 | */ |
| 740 | if (sigmask) { |
| 741 | memcpy(¤t->saved_sigmask, &sigsaved, |
| 742 | sizeof(sigsaved)); |
| 743 | set_restore_sigmask(); |
| 744 | } |
| 745 | } else if (sigmask) |
| 746 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); |
| 747 | |
| 748 | return ret; |
| 749 | } |
| 750 | |
| 751 | /* |
| 752 | * Most architectures can't handle 7-argument syscalls. So we provide a |
| 753 | * 6-argument version where the sixth argument is a pointer to a structure |
| 754 | * which has a pointer to the sigset_t itself followed by a size_t containing |
| 755 | * the sigset size. |
| 756 | */ |
| 757 | SYSCALL_DEFINE6(pselect6, int, n, fd_set __user *, inp, fd_set __user *, outp, |
| 758 | fd_set __user *, exp, struct timespec __user *, tsp, |
| 759 | void __user *, sig) |
| 760 | { |
| 761 | size_t sigsetsize = 0; |
| 762 | sigset_t __user *up = NULL; |
| 763 | |
| 764 | if (sig) { |
| 765 | if (!access_ok(VERIFY_READ, sig, sizeof(void *)+sizeof(size_t)) |
| 766 | || __get_user(up, (sigset_t __user * __user *)sig) |
| 767 | || __get_user(sigsetsize, |
| 768 | (size_t __user *)(sig+sizeof(void *)))) |
| 769 | return -EFAULT; |
| 770 | } |
| 771 | |
| 772 | return do_pselect(n, inp, outp, exp, tsp, up, sigsetsize); |
| 773 | } |
| 774 | |
| 775 | #ifdef __ARCH_WANT_SYS_OLD_SELECT |
| 776 | struct sel_arg_struct { |
| 777 | unsigned long n; |
| 778 | fd_set __user *inp, *outp, *exp; |
| 779 | struct timeval __user *tvp; |
| 780 | }; |
| 781 | |
| 782 | SYSCALL_DEFINE1(old_select, struct sel_arg_struct __user *, arg) |
| 783 | { |
| 784 | struct sel_arg_struct a; |
| 785 | |
| 786 | if (copy_from_user(&a, arg, sizeof(a))) |
| 787 | return -EFAULT; |
| 788 | return kern_select(a.n, a.inp, a.outp, a.exp, a.tvp); |
| 789 | } |
| 790 | #endif |
| 791 | |
| 792 | struct poll_list { |
| 793 | struct poll_list *next; |
| 794 | int len; |
| 795 | struct pollfd entries[0]; |
| 796 | }; |
| 797 | |
| 798 | #define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd)) |
| 799 | |
| 800 | /* |
| 801 | * Fish for pollable events on the pollfd->fd file descriptor. We're only |
| 802 | * interested in events matching the pollfd->events mask, and the result |
| 803 | * matching that mask is both recorded in pollfd->revents and returned. The |
| 804 | * pwait poll_table will be used by the fd-provided poll handler for waiting, |
| 805 | * if pwait->_qproc is non-NULL. |
| 806 | */ |
| 807 | static inline __poll_t do_pollfd(struct pollfd *pollfd, poll_table *pwait, |
| 808 | bool *can_busy_poll, |
| 809 | __poll_t busy_flag) |
| 810 | { |
| 811 | int fd = pollfd->fd; |
| 812 | __poll_t mask = 0, filter; |
| 813 | struct fd f; |
| 814 | |
| 815 | if (fd < 0) |
| 816 | goto out; |
| 817 | mask = EPOLLNVAL; |
| 818 | f = fdget(fd); |
| 819 | if (!f.file) |
| 820 | goto out; |
| 821 | |
| 822 | /* userland u16 ->events contains POLL... bitmap */ |
| 823 | filter = demangle_poll(pollfd->events) | EPOLLERR | EPOLLHUP; |
| 824 | pwait->_key = filter | busy_flag; |
| 825 | mask = vfs_poll(f.file, pwait); |
| 826 | if (mask & busy_flag) |
| 827 | *can_busy_poll = true; |
| 828 | mask &= filter; /* Mask out unneeded events. */ |
| 829 | fdput(f); |
| 830 | |
| 831 | out: |
| 832 | /* ... and so does ->revents */ |
| 833 | pollfd->revents = mangle_poll(mask); |
| 834 | return mask; |
| 835 | } |
| 836 | |
| 837 | static int do_poll(struct poll_list *list, struct poll_wqueues *wait, |
| 838 | struct timespec64 *end_time) |
| 839 | { |
| 840 | poll_table* pt = &wait->pt; |
| 841 | ktime_t expire, *to = NULL; |
| 842 | int timed_out = 0, count = 0; |
| 843 | u64 slack = 0; |
| 844 | __poll_t busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0; |
| 845 | unsigned long busy_start = 0; |
| 846 | |
| 847 | /* Optimise the no-wait case */ |
| 848 | if (end_time && !end_time->tv_sec && !end_time->tv_nsec) { |
| 849 | pt->_qproc = NULL; |
| 850 | timed_out = 1; |
| 851 | } |
| 852 | |
| 853 | if (end_time && !timed_out) |
| 854 | slack = select_estimate_accuracy(end_time); |
| 855 | |
| 856 | for (;;) { |
| 857 | struct poll_list *walk; |
| 858 | bool can_busy_loop = false; |
| 859 | |
| 860 | for (walk = list; walk != NULL; walk = walk->next) { |
| 861 | struct pollfd * pfd, * pfd_end; |
| 862 | |
| 863 | pfd = walk->entries; |
| 864 | pfd_end = pfd + walk->len; |
| 865 | for (; pfd != pfd_end; pfd++) { |
| 866 | /* |
| 867 | * Fish for events. If we found one, record it |
| 868 | * and kill poll_table->_qproc, so we don't |
| 869 | * needlessly register any other waiters after |
| 870 | * this. They'll get immediately deregistered |
| 871 | * when we break out and return. |
| 872 | */ |
| 873 | if (do_pollfd(pfd, pt, &can_busy_loop, |
| 874 | busy_flag)) { |
| 875 | count++; |
| 876 | pt->_qproc = NULL; |
| 877 | /* found something, stop busy polling */ |
| 878 | busy_flag = 0; |
| 879 | can_busy_loop = false; |
| 880 | } |
| 881 | } |
| 882 | } |
| 883 | /* |
| 884 | * All waiters have already been registered, so don't provide |
| 885 | * a poll_table->_qproc to them on the next loop iteration. |
| 886 | */ |
| 887 | pt->_qproc = NULL; |
| 888 | if (!count) { |
| 889 | count = wait->error; |
| 890 | if (signal_pending(current)) |
| 891 | count = -EINTR; |
| 892 | } |
| 893 | if (count || timed_out) |
| 894 | break; |
| 895 | |
| 896 | /* only if found POLL_BUSY_LOOP sockets && not out of time */ |
| 897 | if (can_busy_loop && !need_resched()) { |
| 898 | if (!busy_start) { |
| 899 | busy_start = busy_loop_current_time(); |
| 900 | continue; |
| 901 | } |
| 902 | if (!busy_loop_timeout(busy_start)) |
| 903 | continue; |
| 904 | } |
| 905 | busy_flag = 0; |
| 906 | |
| 907 | /* |
| 908 | * If this is the first loop and we have a timeout |
| 909 | * given, then we convert to ktime_t and set the to |
| 910 | * pointer to the expiry value. |
| 911 | */ |
| 912 | if (end_time && !to) { |
| 913 | expire = timespec64_to_ktime(*end_time); |
| 914 | to = &expire; |
| 915 | } |
| 916 | |
| 917 | if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE, to, slack)) |
| 918 | timed_out = 1; |
| 919 | } |
| 920 | return count; |
| 921 | } |
| 922 | |
| 923 | #define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list)) / \ |
| 924 | sizeof(struct pollfd)) |
| 925 | |
| 926 | static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, |
| 927 | struct timespec64 *end_time) |
| 928 | { |
| 929 | struct poll_wqueues table; |
| 930 | int err = -EFAULT, fdcount, len, size; |
| 931 | /* Allocate small arguments on the stack to save memory and be |
| 932 | faster - use long to make sure the buffer is aligned properly |
| 933 | on 64 bit archs to avoid unaligned access */ |
| 934 | long stack_pps[POLL_STACK_ALLOC/sizeof(long)]; |
| 935 | struct poll_list *const head = (struct poll_list *)stack_pps; |
| 936 | struct poll_list *walk = head; |
| 937 | unsigned long todo = nfds; |
| 938 | |
| 939 | if (nfds > rlimit(RLIMIT_NOFILE)) |
| 940 | return -EINVAL; |
| 941 | |
| 942 | len = min_t(unsigned int, nfds, N_STACK_PPS); |
| 943 | for (;;) { |
| 944 | walk->next = NULL; |
| 945 | walk->len = len; |
| 946 | if (!len) |
| 947 | break; |
| 948 | |
| 949 | if (copy_from_user(walk->entries, ufds + nfds-todo, |
| 950 | sizeof(struct pollfd) * walk->len)) |
| 951 | goto out_fds; |
| 952 | |
| 953 | todo -= walk->len; |
| 954 | if (!todo) |
| 955 | break; |
| 956 | |
| 957 | len = min(todo, POLLFD_PER_PAGE); |
| 958 | size = sizeof(struct poll_list) + sizeof(struct pollfd) * len; |
| 959 | walk = walk->next = kmalloc(size, GFP_KERNEL); |
| 960 | if (!walk) { |
| 961 | err = -ENOMEM; |
| 962 | goto out_fds; |
| 963 | } |
| 964 | } |
| 965 | |
| 966 | poll_initwait(&table); |
| 967 | fdcount = do_poll(head, &table, end_time); |
| 968 | poll_freewait(&table); |
| 969 | |
| 970 | for (walk = head; walk; walk = walk->next) { |
| 971 | struct pollfd *fds = walk->entries; |
| 972 | int j; |
| 973 | |
| 974 | for (j = 0; j < walk->len; j++, ufds++) |
| 975 | if (__put_user(fds[j].revents, &ufds->revents)) |
| 976 | goto out_fds; |
| 977 | } |
| 978 | |
| 979 | err = fdcount; |
| 980 | out_fds: |
| 981 | walk = head->next; |
| 982 | while (walk) { |
| 983 | struct poll_list *pos = walk; |
| 984 | walk = walk->next; |
| 985 | kfree(pos); |
| 986 | } |
| 987 | |
| 988 | return err; |
| 989 | } |
| 990 | |
| 991 | static long do_restart_poll(struct restart_block *restart_block) |
| 992 | { |
| 993 | struct pollfd __user *ufds = restart_block->poll.ufds; |
| 994 | int nfds = restart_block->poll.nfds; |
| 995 | struct timespec64 *to = NULL, end_time; |
| 996 | int ret; |
| 997 | |
| 998 | if (restart_block->poll.has_timeout) { |
| 999 | end_time.tv_sec = restart_block->poll.tv_sec; |
| 1000 | end_time.tv_nsec = restart_block->poll.tv_nsec; |
| 1001 | to = &end_time; |
| 1002 | } |
| 1003 | |
| 1004 | ret = do_sys_poll(ufds, nfds, to); |
| 1005 | |
| 1006 | if (ret == -EINTR) { |
| 1007 | restart_block->fn = do_restart_poll; |
| 1008 | ret = -ERESTART_RESTARTBLOCK; |
| 1009 | } |
| 1010 | return ret; |
| 1011 | } |
| 1012 | |
| 1013 | SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds, |
| 1014 | int, timeout_msecs) |
| 1015 | { |
| 1016 | struct timespec64 end_time, *to = NULL; |
| 1017 | int ret; |
| 1018 | |
| 1019 | if (timeout_msecs >= 0) { |
| 1020 | to = &end_time; |
| 1021 | poll_select_set_timeout(to, timeout_msecs / MSEC_PER_SEC, |
| 1022 | NSEC_PER_MSEC * (timeout_msecs % MSEC_PER_SEC)); |
| 1023 | } |
| 1024 | |
| 1025 | ret = do_sys_poll(ufds, nfds, to); |
| 1026 | |
| 1027 | if (ret == -EINTR) { |
| 1028 | struct restart_block *restart_block; |
| 1029 | |
| 1030 | restart_block = ¤t->restart_block; |
| 1031 | restart_block->fn = do_restart_poll; |
| 1032 | restart_block->poll.ufds = ufds; |
| 1033 | restart_block->poll.nfds = nfds; |
| 1034 | |
| 1035 | if (timeout_msecs >= 0) { |
| 1036 | restart_block->poll.tv_sec = end_time.tv_sec; |
| 1037 | restart_block->poll.tv_nsec = end_time.tv_nsec; |
| 1038 | restart_block->poll.has_timeout = 1; |
| 1039 | } else |
| 1040 | restart_block->poll.has_timeout = 0; |
| 1041 | |
| 1042 | ret = -ERESTART_RESTARTBLOCK; |
| 1043 | } |
| 1044 | return ret; |
| 1045 | } |
| 1046 | |
| 1047 | SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds, |
| 1048 | struct timespec __user *, tsp, const sigset_t __user *, sigmask, |
| 1049 | size_t, sigsetsize) |
| 1050 | { |
| 1051 | sigset_t ksigmask, sigsaved; |
| 1052 | struct timespec64 ts, end_time, *to = NULL; |
| 1053 | int ret; |
| 1054 | |
| 1055 | if (tsp) { |
| 1056 | if (get_timespec64(&ts, tsp)) |
| 1057 | return -EFAULT; |
| 1058 | |
| 1059 | to = &end_time; |
| 1060 | if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec)) |
| 1061 | return -EINVAL; |
| 1062 | } |
| 1063 | |
| 1064 | if (sigmask) { |
| 1065 | /* XXX: Don't preclude handling different sized sigset_t's. */ |
| 1066 | if (sigsetsize != sizeof(sigset_t)) |
| 1067 | return -EINVAL; |
| 1068 | if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) |
| 1069 | return -EFAULT; |
| 1070 | |
| 1071 | sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); |
| 1072 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); |
| 1073 | } |
| 1074 | |
| 1075 | ret = do_sys_poll(ufds, nfds, to); |
| 1076 | |
| 1077 | /* We can restart this syscall, usually */ |
| 1078 | if (ret == -EINTR) { |
| 1079 | /* |
| 1080 | * Don't restore the signal mask yet. Let do_signal() deliver |
| 1081 | * the signal on the way back to userspace, before the signal |
| 1082 | * mask is restored. |
| 1083 | */ |
| 1084 | if (sigmask) { |
| 1085 | memcpy(¤t->saved_sigmask, &sigsaved, |
| 1086 | sizeof(sigsaved)); |
| 1087 | set_restore_sigmask(); |
| 1088 | } |
| 1089 | ret = -ERESTARTNOHAND; |
| 1090 | } else if (sigmask) |
| 1091 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); |
| 1092 | |
| 1093 | ret = poll_select_copy_remaining(&end_time, tsp, 0, ret); |
| 1094 | |
| 1095 | return ret; |
| 1096 | } |
| 1097 | |
| 1098 | #ifdef CONFIG_COMPAT |
| 1099 | #define __COMPAT_NFDBITS (8 * sizeof(compat_ulong_t)) |
| 1100 | |
| 1101 | static |
| 1102 | int compat_poll_select_copy_remaining(struct timespec64 *end_time, void __user *p, |
| 1103 | int timeval, int ret) |
| 1104 | { |
| 1105 | struct timespec64 ts; |
| 1106 | |
| 1107 | if (!p) |
| 1108 | return ret; |
| 1109 | |
| 1110 | if (current->personality & STICKY_TIMEOUTS) |
| 1111 | goto sticky; |
| 1112 | |
| 1113 | /* No update for zero timeout */ |
| 1114 | if (!end_time->tv_sec && !end_time->tv_nsec) |
| 1115 | return ret; |
| 1116 | |
| 1117 | ktime_get_ts64(&ts); |
| 1118 | ts = timespec64_sub(*end_time, ts); |
| 1119 | if (ts.tv_sec < 0) |
| 1120 | ts.tv_sec = ts.tv_nsec = 0; |
| 1121 | |
| 1122 | if (timeval) { |
| 1123 | struct compat_timeval rtv; |
| 1124 | |
| 1125 | rtv.tv_sec = ts.tv_sec; |
| 1126 | rtv.tv_usec = ts.tv_nsec / NSEC_PER_USEC; |
| 1127 | |
| 1128 | if (!copy_to_user(p, &rtv, sizeof(rtv))) |
| 1129 | return ret; |
| 1130 | } else { |
| 1131 | if (!compat_put_timespec64(&ts, p)) |
| 1132 | return ret; |
| 1133 | } |
| 1134 | /* |
| 1135 | * If an application puts its timeval in read-only memory, we |
| 1136 | * don't want the Linux-specific update to the timeval to |
| 1137 | * cause a fault after the select has completed |
| 1138 | * successfully. However, because we're not updating the |
| 1139 | * timeval, we can't restart the system call. |
| 1140 | */ |
| 1141 | |
| 1142 | sticky: |
| 1143 | if (ret == -ERESTARTNOHAND) |
| 1144 | ret = -EINTR; |
| 1145 | return ret; |
| 1146 | } |
| 1147 | |
| 1148 | /* |
| 1149 | * Ooo, nasty. We need here to frob 32-bit unsigned longs to |
| 1150 | * 64-bit unsigned longs. |
| 1151 | */ |
| 1152 | static |
| 1153 | int compat_get_fd_set(unsigned long nr, compat_ulong_t __user *ufdset, |
| 1154 | unsigned long *fdset) |
| 1155 | { |
| 1156 | if (ufdset) { |
| 1157 | return compat_get_bitmap(fdset, ufdset, nr); |
| 1158 | } else { |
| 1159 | zero_fd_set(nr, fdset); |
| 1160 | return 0; |
| 1161 | } |
| 1162 | } |
| 1163 | |
| 1164 | static |
| 1165 | int compat_set_fd_set(unsigned long nr, compat_ulong_t __user *ufdset, |
| 1166 | unsigned long *fdset) |
| 1167 | { |
| 1168 | if (!ufdset) |
| 1169 | return 0; |
| 1170 | return compat_put_bitmap(ufdset, fdset, nr); |
| 1171 | } |
| 1172 | |
| 1173 | |
| 1174 | /* |
| 1175 | * This is a virtual copy of sys_select from fs/select.c and probably |
| 1176 | * should be compared to it from time to time |
| 1177 | */ |
| 1178 | |
| 1179 | /* |
| 1180 | * We can actually return ERESTARTSYS instead of EINTR, but I'd |
| 1181 | * like to be certain this leads to no problems. So I return |
| 1182 | * EINTR just for safety. |
| 1183 | * |
| 1184 | * Update: ERESTARTSYS breaks at least the xview clock binary, so |
| 1185 | * I'm trying ERESTARTNOHAND which restart only when you want to. |
| 1186 | */ |
| 1187 | static int compat_core_sys_select(int n, compat_ulong_t __user *inp, |
| 1188 | compat_ulong_t __user *outp, compat_ulong_t __user *exp, |
| 1189 | struct timespec64 *end_time) |
| 1190 | { |
| 1191 | fd_set_bits fds; |
| 1192 | void *bits; |
| 1193 | int size, max_fds, ret = -EINVAL; |
| 1194 | struct fdtable *fdt; |
| 1195 | long stack_fds[SELECT_STACK_ALLOC/sizeof(long)]; |
| 1196 | |
| 1197 | if (n < 0) |
| 1198 | goto out_nofds; |
| 1199 | |
| 1200 | /* max_fds can increase, so grab it once to avoid race */ |
| 1201 | rcu_read_lock(); |
| 1202 | fdt = files_fdtable(current->files); |
| 1203 | max_fds = fdt->max_fds; |
| 1204 | rcu_read_unlock(); |
| 1205 | if (n > max_fds) |
| 1206 | n = max_fds; |
| 1207 | |
| 1208 | /* |
| 1209 | * We need 6 bitmaps (in/out/ex for both incoming and outgoing), |
| 1210 | * since we used fdset we need to allocate memory in units of |
| 1211 | * long-words. |
| 1212 | */ |
| 1213 | size = FDS_BYTES(n); |
| 1214 | bits = stack_fds; |
| 1215 | if (size > sizeof(stack_fds) / 6) { |
| 1216 | bits = kmalloc_array(6, size, GFP_KERNEL); |
| 1217 | ret = -ENOMEM; |
| 1218 | if (!bits) |
| 1219 | goto out_nofds; |
| 1220 | } |
| 1221 | fds.in = (unsigned long *) bits; |
| 1222 | fds.out = (unsigned long *) (bits + size); |
| 1223 | fds.ex = (unsigned long *) (bits + 2*size); |
| 1224 | fds.res_in = (unsigned long *) (bits + 3*size); |
| 1225 | fds.res_out = (unsigned long *) (bits + 4*size); |
| 1226 | fds.res_ex = (unsigned long *) (bits + 5*size); |
| 1227 | |
| 1228 | if ((ret = compat_get_fd_set(n, inp, fds.in)) || |
| 1229 | (ret = compat_get_fd_set(n, outp, fds.out)) || |
| 1230 | (ret = compat_get_fd_set(n, exp, fds.ex))) |
| 1231 | goto out; |
| 1232 | zero_fd_set(n, fds.res_in); |
| 1233 | zero_fd_set(n, fds.res_out); |
| 1234 | zero_fd_set(n, fds.res_ex); |
| 1235 | |
| 1236 | ret = do_select(n, &fds, end_time); |
| 1237 | |
| 1238 | if (ret < 0) |
| 1239 | goto out; |
| 1240 | if (!ret) { |
| 1241 | ret = -ERESTARTNOHAND; |
| 1242 | if (signal_pending(current)) |
| 1243 | goto out; |
| 1244 | ret = 0; |
| 1245 | } |
| 1246 | |
| 1247 | if (compat_set_fd_set(n, inp, fds.res_in) || |
| 1248 | compat_set_fd_set(n, outp, fds.res_out) || |
| 1249 | compat_set_fd_set(n, exp, fds.res_ex)) |
| 1250 | ret = -EFAULT; |
| 1251 | out: |
| 1252 | if (bits != stack_fds) |
| 1253 | kfree(bits); |
| 1254 | out_nofds: |
| 1255 | return ret; |
| 1256 | } |
| 1257 | |
| 1258 | static int do_compat_select(int n, compat_ulong_t __user *inp, |
| 1259 | compat_ulong_t __user *outp, compat_ulong_t __user *exp, |
| 1260 | struct compat_timeval __user *tvp) |
| 1261 | { |
| 1262 | struct timespec64 end_time, *to = NULL; |
| 1263 | struct compat_timeval tv; |
| 1264 | int ret; |
| 1265 | |
| 1266 | if (tvp) { |
| 1267 | if (copy_from_user(&tv, tvp, sizeof(tv))) |
| 1268 | return -EFAULT; |
| 1269 | |
| 1270 | to = &end_time; |
| 1271 | if (poll_select_set_timeout(to, |
| 1272 | tv.tv_sec + (tv.tv_usec / USEC_PER_SEC), |
| 1273 | (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC)) |
| 1274 | return -EINVAL; |
| 1275 | } |
| 1276 | |
| 1277 | ret = compat_core_sys_select(n, inp, outp, exp, to); |
| 1278 | ret = compat_poll_select_copy_remaining(&end_time, tvp, 1, ret); |
| 1279 | |
| 1280 | return ret; |
| 1281 | } |
| 1282 | |
| 1283 | COMPAT_SYSCALL_DEFINE5(select, int, n, compat_ulong_t __user *, inp, |
| 1284 | compat_ulong_t __user *, outp, compat_ulong_t __user *, exp, |
| 1285 | struct compat_timeval __user *, tvp) |
| 1286 | { |
| 1287 | return do_compat_select(n, inp, outp, exp, tvp); |
| 1288 | } |
| 1289 | |
| 1290 | struct compat_sel_arg_struct { |
| 1291 | compat_ulong_t n; |
| 1292 | compat_uptr_t inp; |
| 1293 | compat_uptr_t outp; |
| 1294 | compat_uptr_t exp; |
| 1295 | compat_uptr_t tvp; |
| 1296 | }; |
| 1297 | |
| 1298 | COMPAT_SYSCALL_DEFINE1(old_select, struct compat_sel_arg_struct __user *, arg) |
| 1299 | { |
| 1300 | struct compat_sel_arg_struct a; |
| 1301 | |
| 1302 | if (copy_from_user(&a, arg, sizeof(a))) |
| 1303 | return -EFAULT; |
| 1304 | return do_compat_select(a.n, compat_ptr(a.inp), compat_ptr(a.outp), |
| 1305 | compat_ptr(a.exp), compat_ptr(a.tvp)); |
| 1306 | } |
| 1307 | |
| 1308 | static long do_compat_pselect(int n, compat_ulong_t __user *inp, |
| 1309 | compat_ulong_t __user *outp, compat_ulong_t __user *exp, |
| 1310 | struct compat_timespec __user *tsp, compat_sigset_t __user *sigmask, |
| 1311 | compat_size_t sigsetsize) |
| 1312 | { |
| 1313 | sigset_t ksigmask, sigsaved; |
| 1314 | struct timespec64 ts, end_time, *to = NULL; |
| 1315 | int ret; |
| 1316 | |
| 1317 | if (tsp) { |
| 1318 | if (compat_get_timespec64(&ts, tsp)) |
| 1319 | return -EFAULT; |
| 1320 | |
| 1321 | to = &end_time; |
| 1322 | if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec)) |
| 1323 | return -EINVAL; |
| 1324 | } |
| 1325 | |
| 1326 | if (sigmask) { |
| 1327 | if (sigsetsize != sizeof(compat_sigset_t)) |
| 1328 | return -EINVAL; |
| 1329 | if (get_compat_sigset(&ksigmask, sigmask)) |
| 1330 | return -EFAULT; |
| 1331 | |
| 1332 | sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); |
| 1333 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); |
| 1334 | } |
| 1335 | |
| 1336 | ret = compat_core_sys_select(n, inp, outp, exp, to); |
| 1337 | ret = compat_poll_select_copy_remaining(&end_time, tsp, 0, ret); |
| 1338 | |
| 1339 | if (ret == -ERESTARTNOHAND) { |
| 1340 | /* |
| 1341 | * Don't restore the signal mask yet. Let do_signal() deliver |
| 1342 | * the signal on the way back to userspace, before the signal |
| 1343 | * mask is restored. |
| 1344 | */ |
| 1345 | if (sigmask) { |
| 1346 | memcpy(¤t->saved_sigmask, &sigsaved, |
| 1347 | sizeof(sigsaved)); |
| 1348 | set_restore_sigmask(); |
| 1349 | } |
| 1350 | } else if (sigmask) |
| 1351 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); |
| 1352 | |
| 1353 | return ret; |
| 1354 | } |
| 1355 | |
| 1356 | COMPAT_SYSCALL_DEFINE6(pselect6, int, n, compat_ulong_t __user *, inp, |
| 1357 | compat_ulong_t __user *, outp, compat_ulong_t __user *, exp, |
| 1358 | struct compat_timespec __user *, tsp, void __user *, sig) |
| 1359 | { |
| 1360 | compat_size_t sigsetsize = 0; |
| 1361 | compat_uptr_t up = 0; |
| 1362 | |
| 1363 | if (sig) { |
| 1364 | if (!access_ok(VERIFY_READ, sig, |
| 1365 | sizeof(compat_uptr_t)+sizeof(compat_size_t)) || |
| 1366 | __get_user(up, (compat_uptr_t __user *)sig) || |
| 1367 | __get_user(sigsetsize, |
| 1368 | (compat_size_t __user *)(sig+sizeof(up)))) |
| 1369 | return -EFAULT; |
| 1370 | } |
| 1371 | return do_compat_pselect(n, inp, outp, exp, tsp, compat_ptr(up), |
| 1372 | sigsetsize); |
| 1373 | } |
| 1374 | |
| 1375 | COMPAT_SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, |
| 1376 | unsigned int, nfds, struct compat_timespec __user *, tsp, |
| 1377 | const compat_sigset_t __user *, sigmask, compat_size_t, sigsetsize) |
| 1378 | { |
| 1379 | sigset_t ksigmask, sigsaved; |
| 1380 | struct timespec64 ts, end_time, *to = NULL; |
| 1381 | int ret; |
| 1382 | |
| 1383 | if (tsp) { |
| 1384 | if (compat_get_timespec64(&ts, tsp)) |
| 1385 | return -EFAULT; |
| 1386 | |
| 1387 | to = &end_time; |
| 1388 | if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec)) |
| 1389 | return -EINVAL; |
| 1390 | } |
| 1391 | |
| 1392 | if (sigmask) { |
| 1393 | if (sigsetsize != sizeof(compat_sigset_t)) |
| 1394 | return -EINVAL; |
| 1395 | if (get_compat_sigset(&ksigmask, sigmask)) |
| 1396 | return -EFAULT; |
| 1397 | |
| 1398 | sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); |
| 1399 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); |
| 1400 | } |
| 1401 | |
| 1402 | ret = do_sys_poll(ufds, nfds, to); |
| 1403 | |
| 1404 | /* We can restart this syscall, usually */ |
| 1405 | if (ret == -EINTR) { |
| 1406 | /* |
| 1407 | * Don't restore the signal mask yet. Let do_signal() deliver |
| 1408 | * the signal on the way back to userspace, before the signal |
| 1409 | * mask is restored. |
| 1410 | */ |
| 1411 | if (sigmask) { |
| 1412 | memcpy(¤t->saved_sigmask, &sigsaved, |
| 1413 | sizeof(sigsaved)); |
| 1414 | set_restore_sigmask(); |
| 1415 | } |
| 1416 | ret = -ERESTARTNOHAND; |
| 1417 | } else if (sigmask) |
| 1418 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); |
| 1419 | |
| 1420 | ret = compat_poll_select_copy_remaining(&end_time, tsp, 0, ret); |
| 1421 | |
| 1422 | return ret; |
| 1423 | } |
| 1424 | #endif |