1450 lines · c
1// SPDX-License-Identifier: GPL-2.02/*3 * This file contains the procedures for the handling of select and poll4 *5 * Created for Linux based loosely upon Mathius Lattner's minix6 * patches by Peter MacDonald. Heavily edited by Linus.7 *8 * 4 February 19949 * COFF/ELF binary emulation. If the process has the STICKY_TIMEOUTS10 * flag set in its personality we do *not* modify the given timeout11 * parameter to reflect time remaining.12 *13 * 24 January 200014 * 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/compat.h>19#include <linux/kernel.h>20#include <linux/sched/signal.h>21#include <linux/sched/rt.h>22#include <linux/syscalls.h>23#include <linux/export.h>24#include <linux/slab.h>25#include <linux/poll.h>26#include <linux/personality.h> /* for STICKY_TIMEOUTS */27#include <linux/file.h>28#include <linux/fdtable.h>29#include <linux/fs.h>30#include <linux/rcupdate.h>31#include <linux/hrtimer.h>32#include <linux/freezer.h>33#include <net/busy_poll.h>34#include <linux/vmalloc.h>35 36#include <linux/uaccess.h>37 38 39/*40 * Estimate expected accuracy in ns from a timeval.41 *42 * After quite a bit of churning around, we've settled on43 * a simple thing of taking 0.1% of the timeout as the44 * slack, with a cap of 100 msec.45 * "nice" tasks get a 0.5% slack instead.46 *47 * Consider this comment an open invitation to come up with even48 * better solutions..49 */50 51#define MAX_SLACK (100 * NSEC_PER_MSEC)52 53static long __estimate_accuracy(struct timespec64 *tv)54{55 long slack;56 int divfactor = 1000;57 58 if (tv->tv_sec < 0)59 return 0;60 61 if (task_nice(current) > 0)62 divfactor = divfactor / 5;63 64 if (tv->tv_sec > MAX_SLACK / (NSEC_PER_SEC/divfactor))65 return MAX_SLACK;66 67 slack = tv->tv_nsec / divfactor;68 slack += tv->tv_sec * (NSEC_PER_SEC/divfactor);69 70 if (slack > MAX_SLACK)71 return MAX_SLACK;72 73 return slack;74}75 76u64 select_estimate_accuracy(struct timespec64 *tv)77{78 u64 ret;79 struct timespec64 now;80 u64 slack = current->timer_slack_ns;81 82 if (slack == 0)83 return 0;84 85 ktime_get_ts64(&now);86 now = timespec64_sub(*tv, now);87 ret = __estimate_accuracy(&now);88 if (ret < slack)89 return slack;90 return ret;91}92 93 94 95struct poll_table_page {96 struct poll_table_page * next;97 struct poll_table_entry * entry;98 struct poll_table_entry entries[];99};100 101#define POLL_TABLE_FULL(table) \102 ((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table))103 104/*105 * Ok, Peter made a complicated, but straightforward multiple_wait() function.106 * I have rewritten this, taking some shortcuts: This code may not be easy to107 * follow, but it should be free of race-conditions, and it's practical. If you108 * understand what I'm doing here, then you understand how the linux109 * sleep/wakeup mechanism works.110 *111 * Two very simple procedures, poll_wait() and poll_freewait() make all the112 * work. poll_wait() is an inline-function defined in <linux/poll.h>,113 * as all select/poll functions have to call it to add an entry to the114 * poll table.115 */116static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,117 poll_table *p);118 119void poll_initwait(struct poll_wqueues *pwq)120{121 init_poll_funcptr(&pwq->pt, __pollwait);122 pwq->polling_task = current;123 pwq->triggered = 0;124 pwq->error = 0;125 pwq->table = NULL;126 pwq->inline_index = 0;127}128EXPORT_SYMBOL(poll_initwait);129 130static void free_poll_entry(struct poll_table_entry *entry)131{132 remove_wait_queue(entry->wait_address, &entry->wait);133 fput(entry->filp);134}135 136void poll_freewait(struct poll_wqueues *pwq)137{138 struct poll_table_page * p = pwq->table;139 int i;140 for (i = 0; i < pwq->inline_index; i++)141 free_poll_entry(pwq->inline_entries + i);142 while (p) {143 struct poll_table_entry * entry;144 struct poll_table_page *old;145 146 entry = p->entry;147 do {148 entry--;149 free_poll_entry(entry);150 } while (entry > p->entries);151 old = p;152 p = p->next;153 free_page((unsigned long) old);154 }155}156EXPORT_SYMBOL(poll_freewait);157 158static struct poll_table_entry *poll_get_entry(struct poll_wqueues *p)159{160 struct poll_table_page *table = p->table;161 162 if (p->inline_index < N_INLINE_POLL_ENTRIES)163 return p->inline_entries + p->inline_index++;164 165 if (!table || POLL_TABLE_FULL(table)) {166 struct poll_table_page *new_table;167 168 new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL);169 if (!new_table) {170 p->error = -ENOMEM;171 return NULL;172 }173 new_table->entry = new_table->entries;174 new_table->next = table;175 p->table = new_table;176 table = new_table;177 }178 179 return table->entry++;180}181 182static HWJS_SUSPENDS int __pollwake(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)183{184 struct poll_wqueues *pwq = wait->private;185 DECLARE_WAITQUEUE(dummy_wait, pwq->polling_task);186 187 /*188 * Although this function is called under waitqueue lock, LOCK189 * doesn't imply write barrier and the users expect write190 * barrier semantics on wakeup functions. The following191 * smp_wmb() is equivalent to smp_wmb() in try_to_wake_up()192 * and is paired with smp_store_mb() in poll_schedule_timeout.193 */194 smp_wmb();195 pwq->triggered = 1;196 197 /*198 * Perform the default wake up operation using a dummy199 * waitqueue.200 *201 * TODO: This is hacky but there currently is no interface to202 * pass in @sync. @sync is scheduled to be removed and once203 * that happens, wake_up_process() can be used directly.204 */205 return default_wake_function(&dummy_wait, mode, sync, key);206}207 208static HWJS_SUSPENDS int pollwake(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)209{210 struct poll_table_entry *entry;211 212 entry = container_of(wait, struct poll_table_entry, wait);213 if (key && !(key_to_poll(key) & entry->key))214 return 0;215 return __pollwake(wait, mode, sync, key);216}217 218/* Add a new entry */219static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,220 poll_table *p)221{222 struct poll_wqueues *pwq = container_of(p, struct poll_wqueues, pt);223 struct poll_table_entry *entry = poll_get_entry(pwq);224 if (!entry)225 return;226 entry->filp = get_file(filp);227 entry->wait_address = wait_address;228 entry->key = p->_key;229 init_waitqueue_func_entry(&entry->wait, pollwake);230 entry->wait.private = pwq;231 add_wait_queue(wait_address, &entry->wait);232}233 234static HWJS_SUSPENDS int poll_schedule_timeout(struct poll_wqueues *pwq, int state,235 ktime_t *expires, unsigned long slack)236{237 int rc = -EINTR;238 239 set_current_state(state);240 if (!pwq->triggered)241 rc = schedule_hrtimeout_range(expires, slack, HRTIMER_MODE_ABS);242 __set_current_state(TASK_RUNNING);243 244 /*245 * Prepare for the next iteration.246 *247 * The following smp_store_mb() serves two purposes. First, it's248 * the counterpart rmb of the wmb in pollwake() such that data249 * written before wake up is always visible after wake up.250 * Second, the full barrier guarantees that triggered clearing251 * doesn't pass event check of the next iteration. Note that252 * this problem doesn't exist for the first iteration as253 * add_wait_queue() has full barrier semantics.254 */255 smp_store_mb(pwq->triggered, 0);256 257 return rc;258}259 260/**261 * poll_select_set_timeout - helper function to setup the timeout value262 * @to: pointer to timespec64 variable for the final timeout263 * @sec: seconds (from user space)264 * @nsec: nanoseconds (from user space)265 *266 * Note, we do not use a timespec for the user space value here, That267 * way we can use the function for timeval and compat interfaces as well.268 *269 * Returns -EINVAL if sec/nsec are not normalized. Otherwise 0.270 */271int poll_select_set_timeout(struct timespec64 *to, time64_t sec, long nsec)272{273 struct timespec64 ts = {.tv_sec = sec, .tv_nsec = nsec};274 275 if (!timespec64_valid(&ts))276 return -EINVAL;277 278 /* Optimize for the zero timeout value here */279 if (!sec && !nsec) {280 to->tv_sec = to->tv_nsec = 0;281 } else {282 ktime_get_ts64(to);283 *to = timespec64_add_safe(*to, ts);284 }285 return 0;286}287 288enum poll_time_type {289 PT_TIMEVAL = 0,290 PT_OLD_TIMEVAL = 1,291 PT_TIMESPEC = 2,292 PT_OLD_TIMESPEC = 3,293};294 295static HWJS_SUSPENDS int poll_select_finish(struct timespec64 *end_time,296 void __user *p,297 enum poll_time_type pt_type, int ret)298{299 struct timespec64 rts;300 301 restore_saved_sigmask_unless(ret == -ERESTARTNOHAND);302 303 if (!p)304 return ret;305 306 if (current->personality & STICKY_TIMEOUTS)307 goto sticky;308 309 /* No update for zero timeout */310 if (!end_time->tv_sec && !end_time->tv_nsec)311 return ret;312 313 ktime_get_ts64(&rts);314 rts = timespec64_sub(*end_time, rts);315 if (rts.tv_sec < 0)316 rts.tv_sec = rts.tv_nsec = 0;317 318 319 switch (pt_type) {320 case PT_TIMEVAL:321 {322 struct __kernel_old_timeval rtv;323 324 if (sizeof(rtv) > sizeof(rtv.tv_sec) + sizeof(rtv.tv_usec))325 memset(&rtv, 0, sizeof(rtv));326 rtv.tv_sec = rts.tv_sec;327 rtv.tv_usec = rts.tv_nsec / NSEC_PER_USEC;328 if (!copy_to_user(p, &rtv, sizeof(rtv)))329 return ret;330 }331 break;332 case PT_OLD_TIMEVAL:333 {334 struct old_timeval32 rtv;335 336 rtv.tv_sec = rts.tv_sec;337 rtv.tv_usec = rts.tv_nsec / NSEC_PER_USEC;338 if (!copy_to_user(p, &rtv, sizeof(rtv)))339 return ret;340 }341 break;342 case PT_TIMESPEC:343 if (!put_timespec64(&rts, p))344 return ret;345 break;346 case PT_OLD_TIMESPEC:347 if (!put_old_timespec32(&rts, p))348 return ret;349 break;350 default:351 BUG();352 }353 /*354 * If an application puts its timeval in read-only memory, we355 * don't want the Linux-specific update to the timeval to356 * cause a fault after the select has completed357 * successfully. However, because we're not updating the358 * timeval, we can't restart the system call.359 */360 361sticky:362 if (ret == -ERESTARTNOHAND)363 ret = -EINTR;364 return ret;365}366 367/*368 * Scalable version of the fd_set.369 */370 371typedef struct {372 unsigned long *in, *out, *ex;373 unsigned long *res_in, *res_out, *res_ex;374} fd_set_bits;375 376/*377 * How many longwords for "nr" bits?378 */379#define FDS_BITPERLONG (8*sizeof(long))380#define FDS_LONGS(nr) (((nr)+FDS_BITPERLONG-1)/FDS_BITPERLONG)381#define FDS_BYTES(nr) (FDS_LONGS(nr)*sizeof(long))382 383/*384 * Use "unsigned long" accesses to let user-mode fd_set's be long-aligned.385 */386static inline387int get_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)388{389 nr = FDS_BYTES(nr);390 if (ufdset)391 return copy_from_user(fdset, ufdset, nr) ? -EFAULT : 0;392 393 memset(fdset, 0, nr);394 return 0;395}396 397static inline unsigned long __must_check398set_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)399{400 if (ufdset)401 return __copy_to_user(ufdset, fdset, FDS_BYTES(nr));402 return 0;403}404 405static inline406void zero_fd_set(unsigned long nr, unsigned long *fdset)407{408 memset(fdset, 0, FDS_BYTES(nr));409}410 411#define FDS_IN(fds, n) (fds->in + n)412#define FDS_OUT(fds, n) (fds->out + n)413#define FDS_EX(fds, n) (fds->ex + n)414 415#define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n))416 417static int max_select_fd(unsigned long n, fd_set_bits *fds)418{419 unsigned long *open_fds;420 unsigned long set;421 int max;422 struct fdtable *fdt;423 424 /* handle last in-complete long-word first */425 set = ~(~0UL << (n & (BITS_PER_LONG-1)));426 n /= BITS_PER_LONG;427 fdt = files_fdtable(current->files);428 open_fds = fdt->open_fds + n;429 max = 0;430 if (set) {431 set &= BITS(fds, n);432 if (set) {433 if (!(set & ~*open_fds))434 goto get_max;435 return -EBADF;436 }437 }438 while (n) {439 open_fds--;440 n--;441 set = BITS(fds, n);442 if (!set)443 continue;444 if (set & ~*open_fds)445 return -EBADF;446 if (max)447 continue;448get_max:449 do {450 max++;451 set >>= 1;452 } while (set);453 max += n * BITS_PER_LONG;454 }455 456 return max;457}458 459#define POLLIN_SET (EPOLLRDNORM | EPOLLRDBAND | EPOLLIN | EPOLLHUP | EPOLLERR |\460 EPOLLNVAL)461#define POLLOUT_SET (EPOLLWRBAND | EPOLLWRNORM | EPOLLOUT | EPOLLERR |\462 EPOLLNVAL)463#define POLLEX_SET (EPOLLPRI | EPOLLNVAL)464 465static inline void wait_key_set(poll_table *wait, unsigned long in,466 unsigned long out, unsigned long bit,467 __poll_t ll_flag)468{469 wait->_key = POLLEX_SET | ll_flag;470 if (in & bit)471 wait->_key |= POLLIN_SET;472 if (out & bit)473 wait->_key |= POLLOUT_SET;474}475 476static HWJS_SUSPENDS noinline_for_stack int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time)477{478 ktime_t expire, *to = NULL;479 struct poll_wqueues table;480 poll_table *wait;481 int retval, i, timed_out = 0;482 u64 slack = 0;483 __poll_t busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;484 unsigned long busy_start = 0;485 486 rcu_read_lock();487 retval = max_select_fd(n, fds);488 rcu_read_unlock();489 490 if (retval < 0)491 return retval;492 n = retval;493 494 poll_initwait(&table);495 wait = &table.pt;496 if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {497 wait->_qproc = NULL;498 timed_out = 1;499 }500 501 if (end_time && !timed_out)502 slack = select_estimate_accuracy(end_time);503 504 retval = 0;505 for (;;) {506 unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp;507 bool can_busy_loop = false;508 509 inp = fds->in; outp = fds->out; exp = fds->ex;510 rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex;511 512 for (i = 0; i < n; ++rinp, ++routp, ++rexp) {513 unsigned long in, out, ex, all_bits, bit = 1, j;514 unsigned long res_in = 0, res_out = 0, res_ex = 0;515 __poll_t mask;516 517 in = *inp++; out = *outp++; ex = *exp++;518 all_bits = in | out | ex;519 if (all_bits == 0) {520 i += BITS_PER_LONG;521 continue;522 }523 524 for (j = 0; j < BITS_PER_LONG; ++j, ++i, bit <<= 1) {525 struct fd f;526 if (i >= n)527 break;528 if (!(bit & all_bits))529 continue;530 mask = EPOLLNVAL;531 f = fdget(i);532 if (fd_file(f)) {533 wait_key_set(wait, in, out, bit,534 busy_flag);535 mask = vfs_poll(fd_file(f), wait);536 537 fdput(f);538 }539 if ((mask & POLLIN_SET) && (in & bit)) {540 res_in |= bit;541 retval++;542 wait->_qproc = NULL;543 }544 if ((mask & POLLOUT_SET) && (out & bit)) {545 res_out |= bit;546 retval++;547 wait->_qproc = NULL;548 }549 if ((mask & POLLEX_SET) && (ex & bit)) {550 res_ex |= bit;551 retval++;552 wait->_qproc = NULL;553 }554 /* got something, stop busy polling */555 if (retval) {556 can_busy_loop = false;557 busy_flag = 0;558 559 /*560 * only remember a returned561 * POLL_BUSY_LOOP if we asked for it562 */563 } else if (busy_flag & mask)564 can_busy_loop = true;565 566 }567 if (res_in)568 *rinp = res_in;569 if (res_out)570 *routp = res_out;571 if (res_ex)572 *rexp = res_ex;573 cond_resched();574 }575 wait->_qproc = NULL;576 if (retval || timed_out || signal_pending(current))577 break;578 if (table.error) {579 retval = table.error;580 break;581 }582 583 /* only if found POLL_BUSY_LOOP sockets && not out of time */584 if (can_busy_loop && !need_resched()) {585 if (!busy_start) {586 busy_start = busy_loop_current_time();587 continue;588 }589 if (!busy_loop_timeout(busy_start))590 continue;591 }592 busy_flag = 0;593 594 /*595 * If this is the first loop and we have a timeout596 * given, then we convert to ktime_t and set the to597 * pointer to the expiry value.598 */599 if (end_time && !to) {600 expire = timespec64_to_ktime(*end_time);601 to = &expire;602 }603 604 if (!poll_schedule_timeout(&table, TASK_INTERRUPTIBLE,605 to, slack))606 timed_out = 1;607 }608 609 poll_freewait(&table);610 611 return retval;612}613 614/*615 * We can actually return ERESTARTSYS instead of EINTR, but I'd616 * like to be certain this leads to no problems. So I return617 * EINTR just for safety.618 *619 * Update: ERESTARTSYS breaks at least the xview clock binary, so620 * I'm trying ERESTARTNOHAND which restart only when you want to.621 */622int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,623 fd_set __user *exp, struct timespec64 *end_time)624{625 fd_set_bits fds;626 void *bits;627 int ret, max_fds;628 size_t size, alloc_size;629 struct fdtable *fdt;630 /* Allocate small arguments on the stack to save memory and be faster */631 long stack_fds[SELECT_STACK_ALLOC/sizeof(long)];632 633 ret = -EINVAL;634 if (n < 0)635 goto out_nofds;636 637 /* max_fds can increase, so grab it once to avoid race */638 rcu_read_lock();639 fdt = files_fdtable(current->files);640 max_fds = fdt->max_fds;641 rcu_read_unlock();642 if (n > max_fds)643 n = max_fds;644 645 /*646 * We need 6 bitmaps (in/out/ex for both incoming and outgoing),647 * since we used fdset we need to allocate memory in units of648 * long-words. 649 */650 size = FDS_BYTES(n);651 bits = stack_fds;652 if (size > sizeof(stack_fds) / 6) {653 /* Not enough space in on-stack array; must use kmalloc */654 ret = -ENOMEM;655 if (size > (SIZE_MAX / 6))656 goto out_nofds;657 658 alloc_size = 6 * size;659 bits = kvmalloc(alloc_size, GFP_KERNEL);660 if (!bits)661 goto out_nofds;662 }663 fds.in = bits;664 fds.out = bits + size;665 fds.ex = bits + 2*size;666 fds.res_in = bits + 3*size;667 fds.res_out = bits + 4*size;668 fds.res_ex = bits + 5*size;669 670 if ((ret = get_fd_set(n, inp, fds.in)) ||671 (ret = get_fd_set(n, outp, fds.out)) ||672 (ret = get_fd_set(n, exp, fds.ex)))673 goto out;674 zero_fd_set(n, fds.res_in);675 zero_fd_set(n, fds.res_out);676 zero_fd_set(n, fds.res_ex);677 678 ret = do_select(n, &fds, end_time);679 680 if (ret < 0)681 goto out;682 if (!ret) {683 ret = -ERESTARTNOHAND;684 if (signal_pending(current))685 goto out;686 ret = 0;687 }688 689 if (set_fd_set(n, inp, fds.res_in) ||690 set_fd_set(n, outp, fds.res_out) ||691 set_fd_set(n, exp, fds.res_ex))692 ret = -EFAULT;693 694out:695 if (bits != stack_fds)696 kvfree(bits);697out_nofds:698 return ret;699}700 701static HWJS_SUSPENDS int kern_select(int n, fd_set __user *inp, fd_set __user *outp,702 fd_set __user *exp, struct __kernel_old_timeval __user *tvp)703{704 struct timespec64 end_time, *to = NULL;705 struct __kernel_old_timeval tv;706 int ret;707 708 if (tvp) {709 if (copy_from_user(&tv, tvp, sizeof(tv)))710 return -EFAULT;711 712 to = &end_time;713 if (poll_select_set_timeout(to,714 tv.tv_sec + (tv.tv_usec / USEC_PER_SEC),715 (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC))716 return -EINVAL;717 }718 719 ret = core_sys_select(n, inp, outp, exp, to);720 return poll_select_finish(&end_time, tvp, PT_TIMEVAL, ret);721}722 723SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp,724 fd_set __user *, exp, struct __kernel_old_timeval __user *, tvp)725{726 return kern_select(n, inp, outp, exp, tvp);727}728 729static HWJS_SUSPENDS long do_pselect(int n, fd_set __user *inp, fd_set __user *outp,730 fd_set __user *exp, void __user *tsp,731 const sigset_t __user *sigmask, size_t sigsetsize,732 enum poll_time_type type)733{734 struct timespec64 ts, end_time, *to = NULL;735 int ret;736 737 if (tsp) {738 switch (type) {739 case PT_TIMESPEC:740 if (get_timespec64(&ts, tsp))741 return -EFAULT;742 break;743 case PT_OLD_TIMESPEC:744 if (get_old_timespec32(&ts, tsp))745 return -EFAULT;746 break;747 default:748 BUG();749 }750 751 to = &end_time;752 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))753 return -EINVAL;754 }755 756 ret = set_user_sigmask(sigmask, sigsetsize);757 if (ret)758 return ret;759 760 ret = core_sys_select(n, inp, outp, exp, to);761 return poll_select_finish(&end_time, tsp, type, ret);762}763 764/*765 * Most architectures can't handle 7-argument syscalls. So we provide a766 * 6-argument version where the sixth argument is a pointer to a structure767 * which has a pointer to the sigset_t itself followed by a size_t containing768 * the sigset size.769 */770struct sigset_argpack {771 sigset_t __user *p;772 size_t size;773};774 775static inline int get_sigset_argpack(struct sigset_argpack *to,776 struct sigset_argpack __user *from)777{778 // the path is hot enough for overhead of copy_from_user() to matter779 if (from) {780 if (can_do_masked_user_access())781 from = masked_user_access_begin(from);782 else if (!user_read_access_begin(from, sizeof(*from)))783 return -EFAULT;784 unsafe_get_user(to->p, &from->p, Efault);785 unsafe_get_user(to->size, &from->size, Efault);786 user_read_access_end();787 }788 return 0;789Efault:790 user_access_end();791 return -EFAULT;792}793 794SYSCALL_DEFINE6(pselect6, int, n, fd_set __user *, inp, fd_set __user *, outp,795 fd_set __user *, exp, struct __kernel_timespec __user *, tsp,796 void __user *, sig)797{798 struct sigset_argpack x = {NULL, 0};799 800 if (get_sigset_argpack(&x, sig))801 return -EFAULT;802 803 return do_pselect(n, inp, outp, exp, tsp, x.p, x.size, PT_TIMESPEC);804}805 806#if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)807 808SYSCALL_DEFINE6(pselect6_time32, int, n, fd_set __user *, inp, fd_set __user *, outp,809 fd_set __user *, exp, struct old_timespec32 __user *, tsp,810 void __user *, sig)811{812 struct sigset_argpack x = {NULL, 0};813 814 if (get_sigset_argpack(&x, sig))815 return -EFAULT;816 817 return do_pselect(n, inp, outp, exp, tsp, x.p, x.size, PT_OLD_TIMESPEC);818}819 820#endif821 822#ifdef __ARCH_WANT_SYS_OLD_SELECT823struct sel_arg_struct {824 unsigned long n;825 fd_set __user *inp, *outp, *exp;826 struct __kernel_old_timeval __user *tvp;827};828 829SYSCALL_DEFINE1(old_select, struct sel_arg_struct __user *, arg)830{831 struct sel_arg_struct a;832 833 if (copy_from_user(&a, arg, sizeof(a)))834 return -EFAULT;835 return kern_select(a.n, a.inp, a.outp, a.exp, a.tvp);836}837#endif838 839struct poll_list {840 struct poll_list *next;841 unsigned int len;842 struct pollfd entries[] __counted_by(len);843};844 845#define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))846 847/*848 * Fish for pollable events on the pollfd->fd file descriptor. We're only849 * interested in events matching the pollfd->events mask, and the result850 * matching that mask is both recorded in pollfd->revents and returned. The851 * pwait poll_table will be used by the fd-provided poll handler for waiting,852 * if pwait->_qproc is non-NULL.853 */854static inline __poll_t do_pollfd(struct pollfd *pollfd, poll_table *pwait,855 bool *can_busy_poll,856 __poll_t busy_flag)857{858 int fd = pollfd->fd;859 __poll_t mask = 0, filter;860 struct fd f;861 862 if (fd < 0)863 goto out;864 mask = EPOLLNVAL;865 f = fdget(fd);866 if (!fd_file(f))867 goto out;868 869 /* userland u16 ->events contains POLL... bitmap */870 filter = demangle_poll(pollfd->events) | EPOLLERR | EPOLLHUP;871 pwait->_key = filter | busy_flag;872 mask = vfs_poll(fd_file(f), pwait);873 if (mask & busy_flag)874 *can_busy_poll = true;875 mask &= filter; /* Mask out unneeded events. */876 fdput(f);877 878out:879 /* ... and so does ->revents */880 pollfd->revents = mangle_poll(mask);881 return mask;882}883 884static HWJS_SUSPENDS int do_poll(struct poll_list *list, struct poll_wqueues *wait,885 struct timespec64 *end_time)886{887 poll_table* pt = &wait->pt;888 ktime_t expire, *to = NULL;889 int timed_out = 0, count = 0;890 u64 slack = 0;891 __poll_t busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;892 unsigned long busy_start = 0;893 894 /* Optimise the no-wait case */895 if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {896 pt->_qproc = NULL;897 timed_out = 1;898 }899 900 if (end_time && !timed_out)901 slack = select_estimate_accuracy(end_time);902 903 for (;;) {904 struct poll_list *walk;905 bool can_busy_loop = false;906 907 for (walk = list; walk != NULL; walk = walk->next) {908 struct pollfd * pfd, * pfd_end;909 910 pfd = walk->entries;911 pfd_end = pfd + walk->len;912 for (; pfd != pfd_end; pfd++) {913 /*914 * Fish for events. If we found one, record it915 * and kill poll_table->_qproc, so we don't916 * needlessly register any other waiters after917 * this. They'll get immediately deregistered918 * when we break out and return.919 */920 if (do_pollfd(pfd, pt, &can_busy_loop,921 busy_flag)) {922 count++;923 pt->_qproc = NULL;924 /* found something, stop busy polling */925 busy_flag = 0;926 can_busy_loop = false;927 }928 }929 }930 /*931 * All waiters have already been registered, so don't provide932 * a poll_table->_qproc to them on the next loop iteration.933 */934 pt->_qproc = NULL;935 if (!count) {936 count = wait->error;937 if (signal_pending(current))938 count = -ERESTARTNOHAND;939 }940 if (count || timed_out)941 break;942 943 /* only if found POLL_BUSY_LOOP sockets && not out of time */944 if (can_busy_loop && !need_resched()) {945 if (!busy_start) {946 busy_start = busy_loop_current_time();947 continue;948 }949 if (!busy_loop_timeout(busy_start))950 continue;951 }952 busy_flag = 0;953 954 /*955 * If this is the first loop and we have a timeout956 * given, then we convert to ktime_t and set the to957 * pointer to the expiry value.958 */959 if (end_time && !to) {960 expire = timespec64_to_ktime(*end_time);961 to = &expire;962 }963 964 if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE, to, slack))965 timed_out = 1;966 }967 return count;968}969 970#define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list)) / \971 sizeof(struct pollfd))972 973static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,974 struct timespec64 *end_time)975{976 struct poll_wqueues table;977 int err = -EFAULT, fdcount;978 /* Allocate small arguments on the stack to save memory and be979 faster - use long to make sure the buffer is aligned properly980 on 64 bit archs to avoid unaligned access */981 long stack_pps[POLL_STACK_ALLOC/sizeof(long)];982 struct poll_list *const head = (struct poll_list *)stack_pps;983 struct poll_list *walk = head;984 unsigned int todo = nfds;985 unsigned int len;986 987 if (nfds > rlimit(RLIMIT_NOFILE))988 return -EINVAL;989 990 len = min_t(unsigned int, nfds, N_STACK_PPS);991 for (;;) {992 walk->next = NULL;993 walk->len = len;994 if (!len)995 break;996 997 if (copy_from_user(walk->entries, ufds + nfds-todo,998 sizeof(struct pollfd) * walk->len))999 goto out_fds;1000 1001 if (walk->len >= todo)1002 break;1003 todo -= walk->len;1004 1005 len = min(todo, POLLFD_PER_PAGE);1006 walk = walk->next = kmalloc(struct_size(walk, entries, len),1007 GFP_KERNEL);1008 if (!walk) {1009 err = -ENOMEM;1010 goto out_fds;1011 }1012 }1013 1014 poll_initwait(&table);1015 fdcount = do_poll(head, &table, end_time);1016 poll_freewait(&table);1017 1018 if (!user_write_access_begin(ufds, nfds * sizeof(*ufds)))1019 goto out_fds;1020 1021 for (walk = head; walk; walk = walk->next) {1022 struct pollfd *fds = walk->entries;1023 unsigned int j;1024 1025 for (j = walk->len; j; fds++, ufds++, j--)1026 unsafe_put_user(fds->revents, &ufds->revents, Efault);1027 }1028 user_write_access_end();1029 1030 err = fdcount;1031out_fds:1032 walk = head->next;1033 while (walk) {1034 struct poll_list *pos = walk;1035 walk = walk->next;1036 kfree(pos);1037 }1038 1039 return err;1040 1041Efault:1042 user_write_access_end();1043 err = -EFAULT;1044 goto out_fds;1045}1046 1047static HWJS_SUSPENDS long do_restart_poll(struct restart_block *restart_block)1048{1049 struct pollfd __user *ufds = restart_block->poll.ufds;1050 int nfds = restart_block->poll.nfds;1051 struct timespec64 *to = NULL, end_time;1052 int ret;1053 1054 if (restart_block->poll.has_timeout) {1055 end_time.tv_sec = restart_block->poll.tv_sec;1056 end_time.tv_nsec = restart_block->poll.tv_nsec;1057 to = &end_time;1058 }1059 1060 ret = do_sys_poll(ufds, nfds, to);1061 1062 if (ret == -ERESTARTNOHAND)1063 ret = set_restart_fn(restart_block, do_restart_poll);1064 1065 return ret;1066}1067 1068SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds,1069 int, timeout_msecs)1070{1071 struct timespec64 end_time, *to = NULL;1072 int ret;1073 1074 if (timeout_msecs >= 0) {1075 to = &end_time;1076 poll_select_set_timeout(to, timeout_msecs / MSEC_PER_SEC,1077 NSEC_PER_MSEC * (timeout_msecs % MSEC_PER_SEC));1078 }1079 1080 ret = do_sys_poll(ufds, nfds, to);1081 1082 if (ret == -ERESTARTNOHAND) {1083 struct restart_block *restart_block;1084 1085 restart_block = ¤t->restart_block;1086 restart_block->poll.ufds = ufds;1087 restart_block->poll.nfds = nfds;1088 1089 if (timeout_msecs >= 0) {1090 restart_block->poll.tv_sec = end_time.tv_sec;1091 restart_block->poll.tv_nsec = end_time.tv_nsec;1092 restart_block->poll.has_timeout = 1;1093 } else1094 restart_block->poll.has_timeout = 0;1095 1096 ret = set_restart_fn(restart_block, do_restart_poll);1097 }1098 return ret;1099}1100 1101SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds,1102 struct __kernel_timespec __user *, tsp, const sigset_t __user *, sigmask,1103 size_t, sigsetsize)1104{1105 struct timespec64 ts, end_time, *to = NULL;1106 int ret;1107 1108 if (tsp) {1109 if (get_timespec64(&ts, tsp))1110 return -EFAULT;1111 1112 to = &end_time;1113 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))1114 return -EINVAL;1115 }1116 1117 ret = set_user_sigmask(sigmask, sigsetsize);1118 if (ret)1119 return ret;1120 1121 ret = do_sys_poll(ufds, nfds, to);1122 return poll_select_finish(&end_time, tsp, PT_TIMESPEC, ret);1123}1124 1125#if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)1126 1127SYSCALL_DEFINE5(ppoll_time32, struct pollfd __user *, ufds, unsigned int, nfds,1128 struct old_timespec32 __user *, tsp, const sigset_t __user *, sigmask,1129 size_t, sigsetsize)1130{1131 struct timespec64 ts, end_time, *to = NULL;1132 int ret;1133 1134 if (tsp) {1135 if (get_old_timespec32(&ts, tsp))1136 return -EFAULT;1137 1138 to = &end_time;1139 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))1140 return -EINVAL;1141 }1142 1143 ret = set_user_sigmask(sigmask, sigsetsize);1144 if (ret)1145 return ret;1146 1147 ret = do_sys_poll(ufds, nfds, to);1148 return poll_select_finish(&end_time, tsp, PT_OLD_TIMESPEC, ret);1149}1150#endif1151 1152#ifdef CONFIG_COMPAT1153#define __COMPAT_NFDBITS (8 * sizeof(compat_ulong_t))1154 1155/*1156 * Ooo, nasty. We need here to frob 32-bit unsigned longs to1157 * 64-bit unsigned longs.1158 */1159static1160int compat_get_fd_set(unsigned long nr, compat_ulong_t __user *ufdset,1161 unsigned long *fdset)1162{1163 if (ufdset) {1164 return compat_get_bitmap(fdset, ufdset, nr);1165 } else {1166 zero_fd_set(nr, fdset);1167 return 0;1168 }1169}1170 1171static1172int compat_set_fd_set(unsigned long nr, compat_ulong_t __user *ufdset,1173 unsigned long *fdset)1174{1175 if (!ufdset)1176 return 0;1177 return compat_put_bitmap(ufdset, fdset, nr);1178}1179 1180 1181/*1182 * This is a virtual copy of sys_select from fs/select.c and probably1183 * should be compared to it from time to time1184 */1185 1186/*1187 * We can actually return ERESTARTSYS instead of EINTR, but I'd1188 * like to be certain this leads to no problems. So I return1189 * EINTR just for safety.1190 *1191 * Update: ERESTARTSYS breaks at least the xview clock binary, so1192 * I'm trying ERESTARTNOHAND which restart only when you want to.1193 */1194static int compat_core_sys_select(int n, compat_ulong_t __user *inp,1195 compat_ulong_t __user *outp, compat_ulong_t __user *exp,1196 struct timespec64 *end_time)1197{1198 fd_set_bits fds;1199 void *bits;1200 int size, max_fds, ret = -EINVAL;1201 struct fdtable *fdt;1202 long stack_fds[SELECT_STACK_ALLOC/sizeof(long)];1203 1204 if (n < 0)1205 goto out_nofds;1206 1207 /* max_fds can increase, so grab it once to avoid race */1208 rcu_read_lock();1209 fdt = files_fdtable(current->files);1210 max_fds = fdt->max_fds;1211 rcu_read_unlock();1212 if (n > max_fds)1213 n = max_fds;1214 1215 /*1216 * We need 6 bitmaps (in/out/ex for both incoming and outgoing),1217 * since we used fdset we need to allocate memory in units of1218 * long-words.1219 */1220 size = FDS_BYTES(n);1221 bits = stack_fds;1222 if (size > sizeof(stack_fds) / 6) {1223 bits = kmalloc_array(6, size, GFP_KERNEL);1224 ret = -ENOMEM;1225 if (!bits)1226 goto out_nofds;1227 }1228 fds.in = (unsigned long *) bits;1229 fds.out = (unsigned long *) (bits + size);1230 fds.ex = (unsigned long *) (bits + 2*size);1231 fds.res_in = (unsigned long *) (bits + 3*size);1232 fds.res_out = (unsigned long *) (bits + 4*size);1233 fds.res_ex = (unsigned long *) (bits + 5*size);1234 1235 if ((ret = compat_get_fd_set(n, inp, fds.in)) ||1236 (ret = compat_get_fd_set(n, outp, fds.out)) ||1237 (ret = compat_get_fd_set(n, exp, fds.ex)))1238 goto out;1239 zero_fd_set(n, fds.res_in);1240 zero_fd_set(n, fds.res_out);1241 zero_fd_set(n, fds.res_ex);1242 1243 ret = do_select(n, &fds, end_time);1244 1245 if (ret < 0)1246 goto out;1247 if (!ret) {1248 ret = -ERESTARTNOHAND;1249 if (signal_pending(current))1250 goto out;1251 ret = 0;1252 }1253 1254 if (compat_set_fd_set(n, inp, fds.res_in) ||1255 compat_set_fd_set(n, outp, fds.res_out) ||1256 compat_set_fd_set(n, exp, fds.res_ex))1257 ret = -EFAULT;1258out:1259 if (bits != stack_fds)1260 kfree(bits);1261out_nofds:1262 return ret;1263}1264 1265static int do_compat_select(int n, compat_ulong_t __user *inp,1266 compat_ulong_t __user *outp, compat_ulong_t __user *exp,1267 struct old_timeval32 __user *tvp)1268{1269 struct timespec64 end_time, *to = NULL;1270 struct old_timeval32 tv;1271 int ret;1272 1273 if (tvp) {1274 if (copy_from_user(&tv, tvp, sizeof(tv)))1275 return -EFAULT;1276 1277 to = &end_time;1278 if (poll_select_set_timeout(to,1279 tv.tv_sec + (tv.tv_usec / USEC_PER_SEC),1280 (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC))1281 return -EINVAL;1282 }1283 1284 ret = compat_core_sys_select(n, inp, outp, exp, to);1285 return poll_select_finish(&end_time, tvp, PT_OLD_TIMEVAL, ret);1286}1287 1288COMPAT_SYSCALL_DEFINE5(select, int, n, compat_ulong_t __user *, inp,1289 compat_ulong_t __user *, outp, compat_ulong_t __user *, exp,1290 struct old_timeval32 __user *, tvp)1291{1292 return do_compat_select(n, inp, outp, exp, tvp);1293}1294 1295struct compat_sel_arg_struct {1296 compat_ulong_t n;1297 compat_uptr_t inp;1298 compat_uptr_t outp;1299 compat_uptr_t exp;1300 compat_uptr_t tvp;1301};1302 1303COMPAT_SYSCALL_DEFINE1(old_select, struct compat_sel_arg_struct __user *, arg)1304{1305 struct compat_sel_arg_struct a;1306 1307 if (copy_from_user(&a, arg, sizeof(a)))1308 return -EFAULT;1309 return do_compat_select(a.n, compat_ptr(a.inp), compat_ptr(a.outp),1310 compat_ptr(a.exp), compat_ptr(a.tvp));1311}1312 1313static long do_compat_pselect(int n, compat_ulong_t __user *inp,1314 compat_ulong_t __user *outp, compat_ulong_t __user *exp,1315 void __user *tsp, compat_sigset_t __user *sigmask,1316 compat_size_t sigsetsize, enum poll_time_type type)1317{1318 struct timespec64 ts, end_time, *to = NULL;1319 int ret;1320 1321 if (tsp) {1322 switch (type) {1323 case PT_OLD_TIMESPEC:1324 if (get_old_timespec32(&ts, tsp))1325 return -EFAULT;1326 break;1327 case PT_TIMESPEC:1328 if (get_timespec64(&ts, tsp))1329 return -EFAULT;1330 break;1331 default:1332 BUG();1333 }1334 1335 to = &end_time;1336 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))1337 return -EINVAL;1338 }1339 1340 ret = set_compat_user_sigmask(sigmask, sigsetsize);1341 if (ret)1342 return ret;1343 1344 ret = compat_core_sys_select(n, inp, outp, exp, to);1345 return poll_select_finish(&end_time, tsp, type, ret);1346}1347 1348struct compat_sigset_argpack {1349 compat_uptr_t p;1350 compat_size_t size;1351};1352static inline int get_compat_sigset_argpack(struct compat_sigset_argpack *to,1353 struct compat_sigset_argpack __user *from)1354{1355 if (from) {1356 if (!user_read_access_begin(from, sizeof(*from)))1357 return -EFAULT;1358 unsafe_get_user(to->p, &from->p, Efault);1359 unsafe_get_user(to->size, &from->size, Efault);1360 user_read_access_end();1361 }1362 return 0;1363Efault:1364 user_access_end();1365 return -EFAULT;1366}1367 1368COMPAT_SYSCALL_DEFINE6(pselect6_time64, int, n, compat_ulong_t __user *, inp,1369 compat_ulong_t __user *, outp, compat_ulong_t __user *, exp,1370 struct __kernel_timespec __user *, tsp, void __user *, sig)1371{1372 struct compat_sigset_argpack x = {0, 0};1373 1374 if (get_compat_sigset_argpack(&x, sig))1375 return -EFAULT;1376 1377 return do_compat_pselect(n, inp, outp, exp, tsp, compat_ptr(x.p),1378 x.size, PT_TIMESPEC);1379}1380 1381#if defined(CONFIG_COMPAT_32BIT_TIME)1382 1383COMPAT_SYSCALL_DEFINE6(pselect6_time32, int, n, compat_ulong_t __user *, inp,1384 compat_ulong_t __user *, outp, compat_ulong_t __user *, exp,1385 struct old_timespec32 __user *, tsp, void __user *, sig)1386{1387 struct compat_sigset_argpack x = {0, 0};1388 1389 if (get_compat_sigset_argpack(&x, sig))1390 return -EFAULT;1391 1392 return do_compat_pselect(n, inp, outp, exp, tsp, compat_ptr(x.p),1393 x.size, PT_OLD_TIMESPEC);1394}1395 1396#endif1397 1398#if defined(CONFIG_COMPAT_32BIT_TIME)1399COMPAT_SYSCALL_DEFINE5(ppoll_time32, struct pollfd __user *, ufds,1400 unsigned int, nfds, struct old_timespec32 __user *, tsp,1401 const compat_sigset_t __user *, sigmask, compat_size_t, sigsetsize)1402{1403 struct timespec64 ts, end_time, *to = NULL;1404 int ret;1405 1406 if (tsp) {1407 if (get_old_timespec32(&ts, tsp))1408 return -EFAULT;1409 1410 to = &end_time;1411 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))1412 return -EINVAL;1413 }1414 1415 ret = set_compat_user_sigmask(sigmask, sigsetsize);1416 if (ret)1417 return ret;1418 1419 ret = do_sys_poll(ufds, nfds, to);1420 return poll_select_finish(&end_time, tsp, PT_OLD_TIMESPEC, ret);1421}1422#endif1423 1424/* New compat syscall for 64 bit time_t*/1425COMPAT_SYSCALL_DEFINE5(ppoll_time64, struct pollfd __user *, ufds,1426 unsigned int, nfds, struct __kernel_timespec __user *, tsp,1427 const compat_sigset_t __user *, sigmask, compat_size_t, sigsetsize)1428{1429 struct timespec64 ts, end_time, *to = NULL;1430 int ret;1431 1432 if (tsp) {1433 if (get_timespec64(&ts, tsp))1434 return -EFAULT;1435 1436 to = &end_time;1437 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))1438 return -EINVAL;1439 }1440 1441 ret = set_compat_user_sigmask(sigmask, sigsetsize);1442 if (ret)1443 return ret;1444 1445 ret = do_sys_poll(ufds, nfds, to);1446 return poll_select_finish(&end_time, tsp, PT_TIMESPEC, ret);1447}1448 1449#endif1450