1/* 2 * linux/kernel/signal.c 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 * 6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson 7 * 8 * 2003-06-02 Jim Houston - Concurrent Computer Corp. 9 * Changes to use preallocated sigqueue structures 10 * to allow signals to be sent reliably. 11 */ 12 13#include <linux/slab.h> 14#include <linux/module.h> 15#include <linux/init.h> 16#include <linux/sched.h> 17#include <linux/fs.h> 18#include <linux/tty.h> 19#include <linux/binfmts.h> 20#include <linux/security.h> 21#include <linux/syscalls.h> 22#include <linux/ptrace.h> 23#include <linux/signal.h> 24#include <linux/signalfd.h> 25#include <linux/ratelimit.h> 26#include <linux/tracehook.h> 27#include <linux/capability.h> 28#include <linux/freezer.h> 29#include <linux/pid_namespace.h> 30#include <linux/nsproxy.h> 31#define CREATE_TRACE_POINTS 32#include <trace/events/signal.h> 33 34#include <asm/param.h> 35#include <asm/uaccess.h> 36#include <asm/unistd.h> 37#include <asm/siginfo.h> 38#include "audit.h" /* audit_signal_info() */ 39 40/* 41 * SLAB caches for signal bits. 42 */ 43 44static struct kmem_cache *sigqueue_cachep; 45 46int print_fatal_signals __read_mostly; 47 48static void __user *sig_handler(struct task_struct *t, int sig) 49{ 50 return t->sighand->action[sig - 1].sa.sa_handler; 51} 52 53static int sig_handler_ignored(void __user *handler, int sig) 54{ 55 /* Is it explicitly or implicitly ignored? */ 56 return handler == SIG_IGN || 57 (handler == SIG_DFL && sig_kernel_ignore(sig)); 58} 59 60static int sig_task_ignored(struct task_struct *t, int sig, 61 int from_ancestor_ns) 62{ 63 void __user *handler; 64 65 handler = sig_handler(t, sig); 66 67 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) && 68 handler == SIG_DFL && !from_ancestor_ns) 69 return 1; 70 71 return sig_handler_ignored(handler, sig); 72} 73 74static int sig_ignored(struct task_struct *t, int sig, int from_ancestor_ns) 75{ 76 /* 77 * Blocked signals are never ignored, since the 78 * signal handler may change by the time it is 79 * unblocked. 80 */ 81 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig)) 82 return 0; 83 84 if (!sig_task_ignored(t, sig, from_ancestor_ns)) 85 return 0; 86 87 /* 88 * Tracers may want to know about even ignored signals. 89 */ 90 return !tracehook_consider_ignored_signal(t, sig); 91} 92 93/* 94 * Re-calculate pending state from the set of locally pending 95 * signals, globally pending signals, and blocked signals. 96 */ 97static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked) 98{ 99 unsigned long ready; 100 long i; 101 102 switch (_NSIG_WORDS) { 103 default: 104 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;) 105 ready |= signal->sig[i] &~ blocked->sig[i]; 106 break; 107 108 case 4: ready = signal->sig[3] &~ blocked->sig[3]; 109 ready |= signal->sig[2] &~ blocked->sig[2]; 110 ready |= signal->sig[1] &~ blocked->sig[1]; 111 ready |= signal->sig[0] &~ blocked->sig[0]; 112 break; 113 114 case 2: ready = signal->sig[1] &~ blocked->sig[1]; 115 ready |= signal->sig[0] &~ blocked->sig[0]; 116 break; 117 118 case 1: ready = signal->sig[0] &~ blocked->sig[0]; 119 } 120 return ready != 0; 121} 122 123#define PENDING(p,b) has_pending_signals(&(p)->signal, (b)) 124 125static int recalc_sigpending_tsk(struct task_struct *t) 126{ 127 if (t->signal->group_stop_count > 0 || 128 PENDING(&t->pending, &t->blocked) || 129 PENDING(&t->signal->shared_pending, &t->blocked)) { 130 set_tsk_thread_flag(t, TIF_SIGPENDING); 131 return 1; 132 } 133 /* 134 * We must never clear the flag in another thread, or in current 135 * when it's possible the current syscall is returning -ERESTART*. 136 * So we don't clear it here, and only callers who know they should do. 137 */ 138 return 0; 139} 140 141/* 142 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up. 143 * This is superfluous when called on current, the wakeup is a harmless no-op. 144 */ 145void recalc_sigpending_and_wake(struct task_struct *t) 146{ 147 if (recalc_sigpending_tsk(t)) 148 signal_wake_up(t, 0); 149} 150 151void recalc_sigpending(void) 152{ 153 if (unlikely(tracehook_force_sigpending())) 154 set_thread_flag(TIF_SIGPENDING); 155 else if (!recalc_sigpending_tsk(current) && !freezing(current)) 156 clear_thread_flag(TIF_SIGPENDING); 157 158} 159 160/* Given the mask, find the first available signal that should be serviced. */ 161 162#define SYNCHRONOUS_MASK \ 163 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \ 164 sigmask(SIGTRAP) | sigmask(SIGFPE)) 165 166int next_signal(struct sigpending *pending, sigset_t *mask) 167{ 168 unsigned long i, *s, *m, x; 169 int sig = 0; 170 171 s = pending->signal.sig; 172 m = mask->sig; 173 174 /* 175 * Handle the first word specially: it contains the 176 * synchronous signals that need to be dequeued first. 177 */ 178 x = *s &~ *m; 179 if (x) { 180 if (x & SYNCHRONOUS_MASK) 181 x &= SYNCHRONOUS_MASK; 182 sig = ffz(~x) + 1; 183 return sig; 184 } 185 186 switch (_NSIG_WORDS) { 187 default: 188 for (i = 1; i < _NSIG_WORDS; ++i) { 189 x = *++s &~ *++m; 190 if (!x) 191 continue; 192 sig = ffz(~x) + i*_NSIG_BPW + 1; 193 break; 194 } 195 break; 196 197 case 2: 198 x = s[1] &~ m[1]; 199 if (!x) 200 break; 201 sig = ffz(~x) + _NSIG_BPW + 1; 202 break; 203 204 case 1: 205 /* Nothing to do */ 206 break; 207 } 208 209 return sig; 210} 211 212static inline void print_dropped_signal(int sig) 213{ 214 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10); 215 216 if (!print_fatal_signals) 217 return; 218 219 if (!__ratelimit(&ratelimit_state)) 220 return; 221 222 printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n", 223 current->comm, current->pid, sig); 224} 225 226/* 227 * allocate a new signal queue record 228 * - this may be called without locks if and only if t == current, otherwise an 229 * appopriate lock must be held to stop the target task from exiting 230 */ 231static struct sigqueue * 232__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit) 233{ 234 struct sigqueue *q = NULL; 235 struct user_struct *user; 236 237 /* 238 * Protect access to @t credentials. This can go away when all 239 * callers hold rcu read lock. 240 */ 241 rcu_read_lock(); 242 user = get_uid(__task_cred(t)->user); 243 atomic_inc(&user->sigpending); 244 rcu_read_unlock(); 245 246 if (override_rlimit || 247 atomic_read(&user->sigpending) <= 248 task_rlimit(t, RLIMIT_SIGPENDING)) { 249 q = kmem_cache_alloc(sigqueue_cachep, flags); 250 } else { 251 print_dropped_signal(sig); 252 } 253 254 if (unlikely(q == NULL)) { 255 atomic_dec(&user->sigpending); 256 free_uid(user); 257 } else { 258 INIT_LIST_HEAD(&q->list); 259 q->flags = 0; 260 q->user = user; 261 } 262 263 return q; 264} 265 266static void __sigqueue_free(struct sigqueue *q) 267{ 268 if (q->flags & SIGQUEUE_PREALLOC) 269 return; 270 atomic_dec(&q->user->sigpending); 271 free_uid(q->user); 272 kmem_cache_free(sigqueue_cachep, q); 273} 274 275void flush_sigqueue(struct sigpending *queue) 276{ 277 struct sigqueue *q; 278 279 sigemptyset(&queue->signal); 280 while (!list_empty(&queue->list)) { 281 q = list_entry(queue->list.next, struct sigqueue , list); 282 list_del_init(&q->list); 283 __sigqueue_free(q); 284 } 285} 286 287/* 288 * Flush all pending signals for a task. 289 */ 290void __flush_signals(struct task_struct *t) 291{ 292 clear_tsk_thread_flag(t, TIF_SIGPENDING); 293 flush_sigqueue(&t->pending); 294 flush_sigqueue(&t->signal->shared_pending); 295} 296 297void flush_signals(struct task_struct *t) 298{ 299 unsigned long flags; 300 301 spin_lock_irqsave(&t->sighand->siglock, flags); 302 __flush_signals(t); 303 spin_unlock_irqrestore(&t->sighand->siglock, flags); 304} 305 306static void __flush_itimer_signals(struct sigpending *pending) 307{ 308 sigset_t signal, retain; 309 struct sigqueue *q, *n; 310 311 signal = pending->signal; 312 sigemptyset(&retain); 313 314 list_for_each_entry_safe(q, n, &pending->list, list) { 315 int sig = q->info.si_signo; 316 317 if (likely(q->info.si_code != SI_TIMER)) { 318 sigaddset(&retain, sig); 319 } else { 320 sigdelset(&signal, sig); 321 list_del_init(&q->list); 322 __sigqueue_free(q); 323 } 324 } 325 326 sigorsets(&pending->signal, &signal, &retain); 327} 328 329void flush_itimer_signals(void) 330{ 331 struct task_struct *tsk = current; 332 unsigned long flags; 333 334 spin_lock_irqsave(&tsk->sighand->siglock, flags); 335 __flush_itimer_signals(&tsk->pending); 336 __flush_itimer_signals(&tsk->signal->shared_pending); 337 spin_unlock_irqrestore(&tsk->sighand->siglock, flags); 338} 339 340void ignore_signals(struct task_struct *t) 341{ 342 int i; 343 344 for (i = 0; i < _NSIG; ++i) 345 t->sighand->action[i].sa.sa_handler = SIG_IGN; 346 347 flush_signals(t); 348} 349 350/* 351 * Flush all handlers for a task. 352 */ 353 354void 355flush_signal_handlers(struct task_struct *t, int force_default) 356{ 357 int i; 358 struct k_sigaction *ka = &t->sighand->action[0]; 359 for (i = _NSIG ; i != 0 ; i--) { 360 if (force_default || ka->sa.sa_handler != SIG_IGN) 361 ka->sa.sa_handler = SIG_DFL; 362 ka->sa.sa_flags = 0; 363 sigemptyset(&ka->sa.sa_mask); 364 ka++; 365 } 366} 367 368int unhandled_signal(struct task_struct *tsk, int sig) 369{ 370 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler; 371 if (is_global_init(tsk)) 372 return 1; 373 if (handler != SIG_IGN && handler != SIG_DFL) 374 return 0; 375 return !tracehook_consider_fatal_signal(tsk, sig); 376} 377 378 379/* Notify the system that a driver wants to block all signals for this 380 * process, and wants to be notified if any signals at all were to be 381 * sent/acted upon. If the notifier routine returns non-zero, then the 382 * signal will be acted upon after all. If the notifier routine returns 0, 383 * then then signal will be blocked. Only one block per process is 384 * allowed. priv is a pointer to private data that the notifier routine 385 * can use to determine if the signal should be blocked or not. */ 386 387void 388block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask) 389{ 390 unsigned long flags; 391 392 spin_lock_irqsave(¤t->sighand->siglock, flags); 393 current->notifier_mask = mask; 394 current->notifier_data = priv; 395 current->notifier = notifier; 396 spin_unlock_irqrestore(¤t->sighand->siglock, flags); 397} 398 399/* Notify the system that blocking has ended. */ 400 401void 402unblock_all_signals(void) 403{ 404 unsigned long flags; 405 406 spin_lock_irqsave(¤t->sighand->siglock, flags); 407 current->notifier = NULL; 408 current->notifier_data = NULL; 409 recalc_sigpending(); 410 spin_unlock_irqrestore(¤t->sighand->siglock, flags); 411} 412 413static void collect_signal(int sig, struct sigpending *list, siginfo_t *info) 414{ 415 struct sigqueue *q, *first = NULL; 416 417 /* 418 * Collect the siginfo appropriate to this signal. Check if 419 * there is another siginfo for the same signal. 420 */ 421 list_for_each_entry(q, &list->list, list) { 422 if (q->info.si_signo == sig) { 423 if (first) 424 goto still_pending; 425 first = q; 426 } 427 } 428 429 sigdelset(&list->signal, sig); 430 431 if (first) { 432still_pending: 433 list_del_init(&first->list); 434 copy_siginfo(info, &first->info); 435 __sigqueue_free(first); 436 } else { 437 /* Ok, it wasn't in the queue. This must be 438 a fast-pathed signal or we must have been 439 out of queue space. So zero out the info. 440 */ 441 info->si_signo = sig; 442 info->si_errno = 0; 443 info->si_code = SI_USER; 444 info->si_pid = 0; 445 info->si_uid = 0; 446 } 447} 448 449static int __dequeue_signal(struct sigpending *pending, sigset_t *mask, 450 siginfo_t *info) 451{ 452 int sig = next_signal(pending, mask); 453 454 if (sig) { 455 if (current->notifier) { 456 if (sigismember(current->notifier_mask, sig)) { 457 if (!(current->notifier)(current->notifier_data)) { 458 clear_thread_flag(TIF_SIGPENDING); 459 return 0; 460 } 461 } 462 } 463 464 collect_signal(sig, pending, info); 465 } 466 467 return sig; 468} 469 470/* 471 * Dequeue a signal and return the element to the caller, which is 472 * expected to free it. 473 * 474 * All callers have to hold the siglock. 475 */ 476int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info) 477{ 478 int signr; 479 480 /* We only dequeue private signals from ourselves, we don't let 481 * signalfd steal them 482 */ 483 signr = __dequeue_signal(&tsk->pending, mask, info); 484 if (!signr) { 485 signr = __dequeue_signal(&tsk->signal->shared_pending, 486 mask, info); 487 /* 488 * itimer signal ? 489 * 490 * itimers are process shared and we restart periodic 491 * itimers in the signal delivery path to prevent DoS 492 * attacks in the high resolution timer case. This is 493 * compliant with the old way of self restarting 494 * itimers, as the SIGALRM is a legacy signal and only 495 * queued once. Changing the restart behaviour to 496 * restart the timer in the signal dequeue path is 497 * reducing the timer noise on heavy loaded !highres 498 * systems too. 499 */ 500 if (unlikely(signr == SIGALRM)) { 501 struct hrtimer *tmr = &tsk->signal->real_timer; 502 503 if (!hrtimer_is_queued(tmr) && 504 tsk->signal->it_real_incr.tv64 != 0) { 505 hrtimer_forward(tmr, tmr->base->get_time(), 506 tsk->signal->it_real_incr); 507 hrtimer_restart(tmr); 508 } 509 } 510 } 511 512 recalc_sigpending(); 513 if (!signr) 514 return 0; 515 516 if (unlikely(sig_kernel_stop(signr))) { 517 /* 518 * Set a marker that we have dequeued a stop signal. Our 519 * caller might release the siglock and then the pending 520 * stop signal it is about to process is no longer in the 521 * pending bitmasks, but must still be cleared by a SIGCONT 522 * (and overruled by a SIGKILL). So those cases clear this 523 * shared flag after we've set it. Note that this flag may 524 * remain set after the signal we return is ignored or 525 * handled. That doesn't matter because its only purpose 526 * is to alert stop-signal processing code when another 527 * processor has come along and cleared the flag. 528 */ 529 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED; 530 } 531 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) { 532 /* 533 * Release the siglock to ensure proper locking order 534 * of timer locks outside of siglocks. Note, we leave 535 * irqs disabled here, since the posix-timers code is 536 * about to disable them again anyway. 537 */ 538 spin_unlock(&tsk->sighand->siglock); 539 do_schedule_next_timer(info); 540 spin_lock(&tsk->sighand->siglock); 541 } 542 return signr; 543} 544 545/* 546 * Tell a process that it has a new active signal.. 547 * 548 * NOTE! we rely on the previous spin_lock to 549 * lock interrupts for us! We can only be called with 550 * "siglock" held, and the local interrupt must 551 * have been disabled when that got acquired! 552 * 553 * No need to set need_resched since signal event passing 554 * goes through ->blocked 555 */ 556void signal_wake_up(struct task_struct *t, int resume) 557{ 558 unsigned int mask; 559 560 set_tsk_thread_flag(t, TIF_SIGPENDING); 561 562 /* 563 * For SIGKILL, we want to wake it up in the stopped/traced/killable 564 * case. We don't check t->state here because there is a race with it 565 * executing another processor and just now entering stopped state. 566 * By using wake_up_state, we ensure the process will wake up and 567 * handle its death signal. 568 */ 569 mask = TASK_INTERRUPTIBLE; 570 if (resume) 571 mask |= TASK_WAKEKILL; 572 if (!wake_up_state(t, mask)) 573 kick_process(t); 574} 575 576/* 577 * Remove signals in mask from the pending set and queue. 578 * Returns 1 if any signals were found. 579 * 580 * All callers must be holding the siglock. 581 * 582 * This version takes a sigset mask and looks at all signals, 583 * not just those in the first mask word. 584 */ 585static int rm_from_queue_full(sigset_t *mask, struct sigpending *s) 586{ 587 struct sigqueue *q, *n; 588 sigset_t m; 589 590 sigandsets(&m, mask, &s->signal); 591 if (sigisemptyset(&m)) 592 return 0; 593 594 signandsets(&s->signal, &s->signal, mask); 595 list_for_each_entry_safe(q, n, &s->list, list) { 596 if (sigismember(mask, q->info.si_signo)) { 597 list_del_init(&q->list); 598 __sigqueue_free(q); 599 } 600 } 601 return 1; 602} 603/* 604 * Remove signals in mask from the pending set and queue. 605 * Returns 1 if any signals were found. 606 * 607 * All callers must be holding the siglock. 608 */ 609static int rm_from_queue(unsigned long mask, struct sigpending *s) 610{ 611 struct sigqueue *q, *n; 612 613 if (!sigtestsetmask(&s->signal, mask)) 614 return 0; 615 616 sigdelsetmask(&s->signal, mask); 617 list_for_each_entry_safe(q, n, &s->list, list) { 618 if (q->info.si_signo < SIGRTMIN && 619 (mask & sigmask(q->info.si_signo))) { 620 list_del_init(&q->list); 621 __sigqueue_free(q); 622 } 623 } 624 return 1; 625} 626 627static inline int is_si_special(const struct siginfo *info) 628{ 629 return info <= SEND_SIG_FORCED; 630} 631 632static inline bool si_fromuser(const struct siginfo *info) 633{ 634 return info == SEND_SIG_NOINFO || 635 (!is_si_special(info) && SI_FROMUSER(info)); 636} 637 638/* 639 * Bad permissions for sending the signal 640 * - the caller must hold the RCU read lock 641 */ 642static int check_kill_permission(int sig, struct siginfo *info, 643 struct task_struct *t) 644{ 645 const struct cred *cred, *tcred; 646 struct pid *sid; 647 int error; 648 649 if (!valid_signal(sig)) 650 return -EINVAL; 651 652 if (!si_fromuser(info)) 653 return 0; 654 655 error = audit_signal_info(sig, t); /* Let audit system see the signal */ 656 if (error) 657 return error; 658 659 cred = current_cred(); 660 tcred = __task_cred(t); 661 if (!same_thread_group(current, t) && 662 (cred->euid ^ tcred->suid) && 663 (cred->euid ^ tcred->uid) && 664 (cred->uid ^ tcred->suid) && 665 (cred->uid ^ tcred->uid) && 666 !capable(CAP_KILL)) { 667 switch (sig) { 668 case SIGCONT: 669 sid = task_session(t); 670 /* 671 * We don't return the error if sid == NULL. The 672 * task was unhashed, the caller must notice this. 673 */ 674 if (!sid || sid == task_session(current)) 675 break; 676 default: 677 return -EPERM; 678 } 679 } 680 681 return security_task_kill(t, info, sig, 0); 682} 683 684/* 685 * Handle magic process-wide effects of stop/continue signals. Unlike 686 * the signal actions, these happen immediately at signal-generation 687 * time regardless of blocking, ignoring, or handling. This does the 688 * actual continuing for SIGCONT, but not the actual stopping for stop 689 * signals. The process stop is done as a signal action for SIG_DFL. 690 * 691 * Returns true if the signal should be actually delivered, otherwise 692 * it should be dropped. 693 */ 694static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns) 695{ 696 struct signal_struct *signal = p->signal; 697 struct task_struct *t; 698 699 if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) { 700 /* 701 * The process is in the middle of dying, nothing to do. 702 */ 703 } else if (sig_kernel_stop(sig)) { 704 /* 705 * This is a stop signal. Remove SIGCONT from all queues. 706 */ 707 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending); 708 t = p; 709 do { 710 rm_from_queue(sigmask(SIGCONT), &t->pending); 711 } while_each_thread(p, t); 712 } else if (sig == SIGCONT) { 713 unsigned int why; 714 /* 715 * Remove all stop signals from all queues, 716 * and wake all threads. 717 */ 718 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending); 719 t = p; 720 do { 721 unsigned int state; 722 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending); 723 /* 724 * If there is a handler for SIGCONT, we must make 725 * sure that no thread returns to user mode before 726 * we post the signal, in case it was the only 727 * thread eligible to run the signal handler--then 728 * it must not do anything between resuming and 729 * running the handler. With the TIF_SIGPENDING 730 * flag set, the thread will pause and acquire the 731 * siglock that we hold now and until we've queued 732 * the pending signal. 733 * 734 * Wake up the stopped thread _after_ setting 735 * TIF_SIGPENDING 736 */ 737 state = __TASK_STOPPED; 738 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) { 739 set_tsk_thread_flag(t, TIF_SIGPENDING); 740 state |= TASK_INTERRUPTIBLE; 741 } 742 wake_up_state(t, state); 743 } while_each_thread(p, t); 744 745 /* 746 * Notify the parent with CLD_CONTINUED if we were stopped. 747 * 748 * If we were in the middle of a group stop, we pretend it 749 * was already finished, and then continued. Since SIGCHLD 750 * doesn't queue we report only CLD_STOPPED, as if the next 751 * CLD_CONTINUED was dropped. 752 */ 753 why = 0; 754 if (signal->flags & SIGNAL_STOP_STOPPED) 755 why |= SIGNAL_CLD_CONTINUED; 756 else if (signal->group_stop_count) 757 why |= SIGNAL_CLD_STOPPED; 758 759 if (why) { 760 /* 761 * The first thread which returns from do_signal_stop() 762 * will take ->siglock, notice SIGNAL_CLD_MASK, and 763 * notify its parent. See get_signal_to_deliver(). 764 */ 765 signal->flags = why | SIGNAL_STOP_CONTINUED; 766 signal->group_stop_count = 0; 767 signal->group_exit_code = 0; 768 } else { 769 /* 770 * We are not stopped, but there could be a stop 771 * signal in the middle of being processed after 772 * being removed from the queue. Clear that too. 773 */ 774 signal->flags &= ~SIGNAL_STOP_DEQUEUED; 775 } 776 } 777 778 return !sig_ignored(p, sig, from_ancestor_ns); 779} 780 781/* 782 * Test if P wants to take SIG. After we've checked all threads with this, 783 * it's equivalent to finding no threads not blocking SIG. Any threads not 784 * blocking SIG were ruled out because they are not running and already 785 * have pending signals. Such threads will dequeue from the shared queue 786 * as soon as they're available, so putting the signal on the shared queue 787 * will be equivalent to sending it to one such thread. 788 */ 789static inline int wants_signal(int sig, struct task_struct *p) 790{ 791 if (sigismember(&p->blocked, sig)) 792 return 0; 793 if (p->flags & PF_EXITING) 794 return 0; 795 if (sig == SIGKILL) 796 return 1; 797 if (task_is_stopped_or_traced(p)) 798 return 0; 799 return task_curr(p) || !signal_pending(p); 800} 801 802static void complete_signal(int sig, struct task_struct *p, int group) 803{ 804 struct signal_struct *signal = p->signal; 805 struct task_struct *t; 806 807 /* 808 * Now find a thread we can wake up to take the signal off the queue. 809 * 810 * If the main thread wants the signal, it gets first crack. 811 * Probably the least surprising to the average bear. 812 */ 813 if (wants_signal(sig, p)) 814 t = p; 815 else if (!group || thread_group_empty(p)) 816 /* 817 * There is just one thread and it does not need to be woken. 818 * It will dequeue unblocked signals before it runs again. 819 */ 820 return; 821 else { 822 /* 823 * Otherwise try to find a suitable thread. 824 */ 825 t = signal->curr_target; 826 while (!wants_signal(sig, t)) { 827 t = next_thread(t); 828 if (t == signal->curr_target) 829 /* 830 * No thread needs to be woken. 831 * Any eligible threads will see 832 * the signal in the queue soon. 833 */ 834 return; 835 } 836 signal->curr_target = t; 837 } 838 839 /* 840 * Found a killable thread. If the signal will be fatal, 841 * then start taking the whole group down immediately. 842 */ 843 if (sig_fatal(p, sig) && 844 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) && 845 !sigismember(&t->real_blocked, sig) && 846 (sig == SIGKILL || 847 !tracehook_consider_fatal_signal(t, sig))) { 848 /* 849 * This signal will be fatal to the whole group. 850 */ 851 if (!sig_kernel_coredump(sig)) { 852 /* 853 * Start a group exit and wake everybody up. 854 * This way we don't have other threads 855 * running and doing things after a slower 856 * thread has the fatal signal pending. 857 */ 858 signal->flags = SIGNAL_GROUP_EXIT; 859 signal->group_exit_code = sig; 860 signal->group_stop_count = 0; 861 t = p; 862 do { 863 sigaddset(&t->pending.signal, SIGKILL); 864 signal_wake_up(t, 1); 865 } while_each_thread(p, t); 866 return; 867 } 868 } 869 870 /* 871 * The signal is already in the shared-pending queue. 872 * Tell the chosen thread to wake up and dequeue it. 873 */ 874 signal_wake_up(t, sig == SIGKILL); 875 return; 876} 877 878static inline int legacy_queue(struct sigpending *signals, int sig) 879{ 880 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig); 881} 882 883static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, 884 int group, int from_ancestor_ns) 885{ 886 struct sigpending *pending; 887 struct sigqueue *q; 888 int override_rlimit; 889 890 trace_signal_generate(sig, info, t); 891 892 assert_spin_locked(&t->sighand->siglock); 893 894 if (!prepare_signal(sig, t, from_ancestor_ns)) 895 return 0; 896 897 pending = group ? &t->signal->shared_pending : &t->pending; 898 /* 899 * Short-circuit ignored signals and support queuing 900 * exactly one non-rt signal, so that we can get more 901 * detailed information about the cause of the signal. 902 */ 903 if (legacy_queue(pending, sig)) 904 return 0; 905 /* 906 * fast-pathed signals for kernel-internal things like SIGSTOP 907 * or SIGKILL. 908 */ 909 if (info == SEND_SIG_FORCED) 910 goto out_set; 911 912 /* Real-time signals must be queued if sent by sigqueue, or 913 some other real-time mechanism. It is implementation 914 defined whether kill() does so. We attempt to do so, on 915 the principle of least surprise, but since kill is not 916 allowed to fail with EAGAIN when low on memory we just 917 make sure at least one signal gets delivered and don't 918 pass on the info struct. */ 919 920 if (sig < SIGRTMIN) 921 override_rlimit = (is_si_special(info) || info->si_code >= 0); 922 else 923 override_rlimit = 0; 924 925 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE, 926 override_rlimit); 927 if (q) { 928 list_add_tail(&q->list, &pending->list); 929 switch ((unsigned long) info) { 930 case (unsigned long) SEND_SIG_NOINFO: 931 q->info.si_signo = sig; 932 q->info.si_errno = 0; 933 q->info.si_code = SI_USER; 934 q->info.si_pid = task_tgid_nr_ns(current, 935 task_active_pid_ns(t)); 936 q->info.si_uid = current_uid(); 937 break; 938 case (unsigned long) SEND_SIG_PRIV: 939 q->info.si_signo = sig; 940 q->info.si_errno = 0; 941 q->info.si_code = SI_KERNEL; 942 q->info.si_pid = 0; 943 q->info.si_uid = 0; 944 break; 945 default: 946 copy_siginfo(&q->info, info); 947 if (from_ancestor_ns) 948 q->info.si_pid = 0; 949 break; 950 } 951 } else if (!is_si_special(info)) { 952 if (sig >= SIGRTMIN && info->si_code != SI_USER) { 953 /* 954 * Queue overflow, abort. We may abort if the 955 * signal was rt and sent by user using something 956 * other than kill(). 957 */ 958 trace_signal_overflow_fail(sig, group, info); 959 return -EAGAIN; 960 } else { 961 /* 962 * This is a silent loss of information. We still 963 * send the signal, but the *info bits are lost. 964 */ 965 trace_signal_lose_info(sig, group, info); 966 } 967 } 968 969out_set: 970 signalfd_notify(t, sig); 971 sigaddset(&pending->signal, sig); 972 complete_signal(sig, t, group); 973 return 0; 974} 975 976static int send_signal(int sig, struct siginfo *info, struct task_struct *t, 977 int group) 978{ 979 int from_ancestor_ns = 0; 980 981#ifdef CONFIG_PID_NS 982 from_ancestor_ns = si_fromuser(info) && 983 !task_pid_nr_ns(current, task_active_pid_ns(t)); 984#endif 985 986 return __send_signal(sig, info, t, group, from_ancestor_ns); 987} 988 989static void print_fatal_signal(struct pt_regs *regs, int signr) 990{ 991 printk("%s/%d: potentially unexpected fatal signal %d.\n", 992 current->comm, task_pid_nr(current), signr); 993 994#if defined(__i386__) && !defined(__arch_um__) 995 printk("code at %08lx: ", regs->ip); 996 { 997 int i; 998 for (i = 0; i < 16; i++) { 999 unsigned char insn; 1000 1001 if (get_user(insn, (unsigned char *)(regs->ip + i))) 1002 break; 1003 printk("%02x ", insn); 1004 } 1005 } 1006#endif 1007 printk("\n"); 1008 preempt_disable(); 1009 show_regs(regs); 1010 preempt_enable(); 1011} 1012 1013static int __init setup_print_fatal_signals(char *str) 1014{ 1015 get_option (&str, &print_fatal_signals); 1016 1017 return 1; 1018} 1019 1020__setup("print-fatal-signals=", setup_print_fatal_signals); 1021 1022int 1023__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p) 1024{ 1025 return send_signal(sig, info, p, 1); 1026} 1027 1028static int 1029specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t) 1030{ 1031 return send_signal(sig, info, t, 0); 1032} 1033 1034int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p, 1035 bool group) 1036{ 1037 unsigned long flags; 1038 int ret = -ESRCH; 1039 1040 if (lock_task_sighand(p, &flags)) { 1041 ret = send_signal(sig, info, p, group); 1042 unlock_task_sighand(p, &flags); 1043 } 1044 1045 return ret; 1046} 1047 1048/* 1049 * Force a signal that the process can't ignore: if necessary 1050 * we unblock the signal and change any SIG_IGN to SIG_DFL. 1051 * 1052 * Note: If we unblock the signal, we always reset it to SIG_DFL, 1053 * since we do not want to have a signal handler that was blocked 1054 * be invoked when user space had explicitly blocked it. 1055 * 1056 * We don't want to have recursive SIGSEGV's etc, for example, 1057 * that is why we also clear SIGNAL_UNKILLABLE. 1058 */ 1059int 1060force_sig_info(int sig, struct siginfo *info, struct task_struct *t) 1061{ 1062 unsigned long int flags; 1063 int ret, blocked, ignored; 1064 struct k_sigaction *action; 1065 1066 spin_lock_irqsave(&t->sighand->siglock, flags); 1067 action = &t->sighand->action[sig-1]; 1068 ignored = action->sa.sa_handler == SIG_IGN; 1069 blocked = sigismember(&t->blocked, sig); 1070 if (blocked || ignored) { 1071 action->sa.sa_handler = SIG_DFL; 1072 if (blocked) { 1073 sigdelset(&t->blocked, sig); 1074 recalc_sigpending_and_wake(t); 1075 } 1076 } 1077 if (action->sa.sa_handler == SIG_DFL) 1078 t->signal->flags &= ~SIGNAL_UNKILLABLE; 1079 ret = specific_send_sig_info(sig, info, t); 1080 spin_unlock_irqrestore(&t->sighand->siglock, flags); 1081 1082 return ret; 1083} 1084 1085/* 1086 * Nuke all other threads in the group. 1087 */ 1088int zap_other_threads(struct task_struct *p) 1089{ 1090 struct task_struct *t = p; 1091 int count = 0; 1092 1093 p->signal->group_stop_count = 0; 1094 1095 while_each_thread(p, t) { 1096 count++; 1097 1098 /* Don't bother with already dead threads */ 1099 if (t->exit_state) 1100 continue; 1101 sigaddset(&t->pending.signal, SIGKILL); 1102 signal_wake_up(t, 1); 1103 } 1104 1105 return count; 1106} 1107 1108struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags) 1109{ 1110 struct sighand_struct *sighand; 1111 1112 rcu_read_lock(); 1113 for (;;) { 1114 sighand = rcu_dereference(tsk->sighand); 1115 if (unlikely(sighand == NULL)) 1116 break; 1117 1118 spin_lock_irqsave(&sighand->siglock, *flags); 1119 if (likely(sighand == tsk->sighand)) 1120 break; 1121 spin_unlock_irqrestore(&sighand->siglock, *flags); 1122 } 1123 rcu_read_unlock(); 1124 1125 return sighand; 1126} 1127 1128/* 1129 * send signal info to all the members of a group 1130 */ 1131int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p) 1132{ 1133 int ret; 1134 1135 rcu_read_lock(); 1136 ret = check_kill_permission(sig, info, p); 1137 rcu_read_unlock(); 1138 1139 if (!ret && sig) 1140 ret = do_send_sig_info(sig, info, p, true); 1141 1142 return ret; 1143} 1144 1145/* 1146 * __kill_pgrp_info() sends a signal to a process group: this is what the tty 1147 * control characters do (^C, ^Z etc) 1148 * - the caller must hold at least a readlock on tasklist_lock 1149 */ 1150int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp) 1151{ 1152 struct task_struct *p = NULL; 1153 int retval, success; 1154 1155 success = 0; 1156 retval = -ESRCH; 1157 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 1158 int err = group_send_sig_info(sig, info, p); 1159 success |= !err; 1160 retval = err; 1161 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 1162 return success ? 0 : retval; 1163} 1164 1165int kill_pid_info(int sig, struct siginfo *info, struct pid *pid) 1166{ 1167 int error = -ESRCH; 1168 struct task_struct *p; 1169 1170 rcu_read_lock(); 1171retry: 1172 p = pid_task(pid, PIDTYPE_PID); 1173 if (p) { 1174 error = group_send_sig_info(sig, info, p); 1175 if (unlikely(error == -ESRCH)) 1176 /* 1177 * The task was unhashed in between, try again. 1178 * If it is dead, pid_task() will return NULL, 1179 * if we race with de_thread() it will find the 1180 * new leader. 1181 */ 1182 goto retry; 1183 } 1184 rcu_read_unlock(); 1185 1186 return error; 1187} 1188 1189int 1190kill_proc_info(int sig, struct siginfo *info, pid_t pid) 1191{ 1192 int error; 1193 rcu_read_lock(); 1194 error = kill_pid_info(sig, info, find_vpid(pid)); 1195 rcu_read_unlock(); 1196 return error; 1197} 1198 1199/*Foxconn modify start by Hank 08/10/2012 */ 1200/*add a function for user space using*/ 1201#define __si_special(priv) \ 1202 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO) 1203 1204int 1205kill_proc(pid_t pid, int sig, int priv) 1206{ 1207 return kill_proc_info(sig, __si_special(priv), pid); 1208} 1209EXPORT_SYMBOL(kill_proc); 1210/*Foxconn modify end by Hank 08/10/2012 */ 1211/* like kill_pid_info(), but doesn't use uid/euid of "current" */ 1212int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid, 1213 uid_t uid, uid_t euid, u32 secid) 1214{ 1215 int ret = -EINVAL; 1216 struct task_struct *p; 1217 const struct cred *pcred; 1218 unsigned long flags; 1219 1220 if (!valid_signal(sig)) 1221 return ret; 1222 1223 rcu_read_lock(); 1224 p = pid_task(pid, PIDTYPE_PID); 1225 if (!p) { 1226 ret = -ESRCH; 1227 goto out_unlock; 1228 } 1229 pcred = __task_cred(p); 1230 if (si_fromuser(info) && 1231 euid != pcred->suid && euid != pcred->uid && 1232 uid != pcred->suid && uid != pcred->uid) { 1233 ret = -EPERM; 1234 goto out_unlock; 1235 } 1236 ret = security_task_kill(p, info, sig, secid); 1237 if (ret) 1238 goto out_unlock; 1239 1240 if (sig) { 1241 if (lock_task_sighand(p, &flags)) { 1242 ret = __send_signal(sig, info, p, 1, 0); 1243 unlock_task_sighand(p, &flags); 1244 } else 1245 ret = -ESRCH; 1246 } 1247out_unlock: 1248 rcu_read_unlock(); 1249 return ret; 1250} 1251EXPORT_SYMBOL_GPL(kill_pid_info_as_uid); 1252 1253/* 1254 * kill_something_info() interprets pid in interesting ways just like kill(2). 1255 * 1256 * POSIX specifies that kill(-1,sig) is unspecified, but what we have 1257 * is probably wrong. Should make it like BSD or SYSV. 1258 */ 1259 1260static int kill_something_info(int sig, struct siginfo *info, pid_t pid) 1261{ 1262 int ret; 1263 1264 if (pid > 0) { 1265 rcu_read_lock(); 1266 ret = kill_pid_info(sig, info, find_vpid(pid)); 1267 rcu_read_unlock(); 1268 return ret; 1269 } 1270 1271 read_lock(&tasklist_lock); 1272 if (pid != -1) { 1273 ret = __kill_pgrp_info(sig, info, 1274 pid ? find_vpid(-pid) : task_pgrp(current)); 1275 } else { 1276 int retval = 0, count = 0; 1277 struct task_struct * p; 1278 1279 for_each_process(p) { 1280 if (task_pid_vnr(p) > 1 && 1281 !same_thread_group(p, current)) { 1282 int err = group_send_sig_info(sig, info, p); 1283 ++count; 1284 if (err != -EPERM) 1285 retval = err; 1286 } 1287 } 1288 ret = count ? retval : -ESRCH; 1289 } 1290 read_unlock(&tasklist_lock); 1291 1292 return ret; 1293} 1294 1295/* 1296 * These are for backward compatibility with the rest of the kernel source. 1297 */ 1298 1299int 1300send_sig_info(int sig, struct siginfo *info, struct task_struct *p) 1301{ 1302 /* 1303 * Make sure legacy kernel users don't send in bad values 1304 * (normal paths check this in check_kill_permission). 1305 */ 1306 if (!valid_signal(sig)) 1307 return -EINVAL; 1308 1309 return do_send_sig_info(sig, info, p, false); 1310} 1311 1312int 1313send_sig(int sig, struct task_struct *p, int priv) 1314{ 1315 return send_sig_info(sig, __si_special(priv), p); 1316} 1317 1318void 1319force_sig(int sig, struct task_struct *p) 1320{ 1321 force_sig_info(sig, SEND_SIG_PRIV, p); 1322} 1323 1324/* 1325 * When things go south during signal handling, we 1326 * will force a SIGSEGV. And if the signal that caused 1327 * the problem was already a SIGSEGV, we'll want to 1328 * make sure we don't even try to deliver the signal.. 1329 */ 1330int 1331force_sigsegv(int sig, struct task_struct *p) 1332{ 1333 if (sig == SIGSEGV) { 1334 unsigned long flags; 1335 spin_lock_irqsave(&p->sighand->siglock, flags); 1336 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL; 1337 spin_unlock_irqrestore(&p->sighand->siglock, flags); 1338 } 1339 force_sig(SIGSEGV, p); 1340 return 0; 1341} 1342 1343int kill_pgrp(struct pid *pid, int sig, int priv) 1344{ 1345 int ret; 1346 1347 read_lock(&tasklist_lock); 1348 ret = __kill_pgrp_info(sig, __si_special(priv), pid); 1349 read_unlock(&tasklist_lock); 1350 1351 return ret; 1352} 1353EXPORT_SYMBOL(kill_pgrp); 1354 1355int kill_pid(struct pid *pid, int sig, int priv) 1356{ 1357 return kill_pid_info(sig, __si_special(priv), pid); 1358} 1359EXPORT_SYMBOL(kill_pid); 1360 1361/* 1362 * These functions support sending signals using preallocated sigqueue 1363 * structures. This is needed "because realtime applications cannot 1364 * afford to lose notifications of asynchronous events, like timer 1365 * expirations or I/O completions". In the case of Posix Timers 1366 * we allocate the sigqueue structure from the timer_create. If this 1367 * allocation fails we are able to report the failure to the application 1368 * with an EAGAIN error. 1369 */ 1370struct sigqueue *sigqueue_alloc(void) 1371{ 1372 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0); 1373 1374 if (q) 1375 q->flags |= SIGQUEUE_PREALLOC; 1376 1377 return q; 1378} 1379 1380void sigqueue_free(struct sigqueue *q) 1381{ 1382 unsigned long flags; 1383 spinlock_t *lock = ¤t->sighand->siglock; 1384 1385 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); 1386 /* 1387 * We must hold ->siglock while testing q->list 1388 * to serialize with collect_signal() or with 1389 * __exit_signal()->flush_sigqueue(). 1390 */ 1391 spin_lock_irqsave(lock, flags); 1392 q->flags &= ~SIGQUEUE_PREALLOC; 1393 /* 1394 * If it is queued it will be freed when dequeued, 1395 * like the "regular" sigqueue. 1396 */ 1397 if (!list_empty(&q->list)) 1398 q = NULL; 1399 spin_unlock_irqrestore(lock, flags); 1400 1401 if (q) 1402 __sigqueue_free(q); 1403} 1404 1405int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group) 1406{ 1407 int sig = q->info.si_signo; 1408 struct sigpending *pending; 1409 unsigned long flags; 1410 int ret; 1411 1412 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); 1413 1414 ret = -1; 1415 if (!likely(lock_task_sighand(t, &flags))) 1416 goto ret; 1417 1418 ret = 1; /* the signal is ignored */ 1419 if (!prepare_signal(sig, t, 0)) 1420 goto out; 1421 1422 ret = 0; 1423 if (unlikely(!list_empty(&q->list))) { 1424 /* 1425 * If an SI_TIMER entry is already queue just increment 1426 * the overrun count. 1427 */ 1428 BUG_ON(q->info.si_code != SI_TIMER); 1429 q->info.si_overrun++; 1430 goto out; 1431 } 1432 q->info.si_overrun = 0; 1433 1434 signalfd_notify(t, sig); 1435 pending = group ? &t->signal->shared_pending : &t->pending; 1436 list_add_tail(&q->list, &pending->list); 1437 sigaddset(&pending->signal, sig); 1438 complete_signal(sig, t, group); 1439out: 1440 unlock_task_sighand(t, &flags); 1441ret: 1442 return ret; 1443} 1444 1445/* 1446 * Let a parent know about the death of a child. 1447 * For a stopped/continued status change, use do_notify_parent_cldstop instead. 1448 * 1449 * Returns -1 if our parent ignored us and so we've switched to 1450 * self-reaping, or else @sig. 1451 */ 1452int do_notify_parent(struct task_struct *tsk, int sig) 1453{ 1454 struct siginfo info; 1455 unsigned long flags; 1456 struct sighand_struct *psig; 1457 int ret = sig; 1458 1459 BUG_ON(sig == -1); 1460 1461 /* do_notify_parent_cldstop should have been called instead. */ 1462 BUG_ON(task_is_stopped_or_traced(tsk)); 1463 1464 BUG_ON(!task_ptrace(tsk) && 1465 (tsk->group_leader != tsk || !thread_group_empty(tsk))); 1466 1467 info.si_signo = sig; 1468 info.si_errno = 0; 1469 /* 1470 * we are under tasklist_lock here so our parent is tied to 1471 * us and cannot exit and release its namespace. 1472 * 1473 * the only it can is to switch its nsproxy with sys_unshare, 1474 * bu uncharing pid namespaces is not allowed, so we'll always 1475 * see relevant namespace 1476 * 1477 * write_lock() currently calls preempt_disable() which is the 1478 * same as rcu_read_lock(), but according to Oleg, this is not 1479 * correct to rely on this 1480 */ 1481 rcu_read_lock(); 1482 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns); 1483 info.si_uid = __task_cred(tsk)->uid; 1484 rcu_read_unlock(); 1485 1486 info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime, 1487 tsk->signal->utime)); 1488 info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime, 1489 tsk->signal->stime)); 1490 1491 info.si_status = tsk->exit_code & 0x7f; 1492 if (tsk->exit_code & 0x80) 1493 info.si_code = CLD_DUMPED; 1494 else if (tsk->exit_code & 0x7f) 1495 info.si_code = CLD_KILLED; 1496 else { 1497 info.si_code = CLD_EXITED; 1498 info.si_status = tsk->exit_code >> 8; 1499 } 1500 1501 psig = tsk->parent->sighand; 1502 spin_lock_irqsave(&psig->siglock, flags); 1503 if (!task_ptrace(tsk) && sig == SIGCHLD && 1504 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN || 1505 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) { 1506 /* 1507 * We are exiting and our parent doesn't care. POSIX.1 1508 * defines special semantics for setting SIGCHLD to SIG_IGN 1509 * or setting the SA_NOCLDWAIT flag: we should be reaped 1510 * automatically and not left for our parent's wait4 call. 1511 * Rather than having the parent do it as a magic kind of 1512 * signal handler, we just set this to tell do_exit that we 1513 * can be cleaned up without becoming a zombie. Note that 1514 * we still call __wake_up_parent in this case, because a 1515 * blocked sys_wait4 might now return -ECHILD. 1516 * 1517 * Whether we send SIGCHLD or not for SA_NOCLDWAIT 1518 * is implementation-defined: we do (if you don't want 1519 * it, just use SIG_IGN instead). 1520 */ 1521 ret = tsk->exit_signal = -1; 1522 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) 1523 sig = -1; 1524 } 1525 if (valid_signal(sig) && sig > 0) 1526 __group_send_sig_info(sig, &info, tsk->parent); 1527 __wake_up_parent(tsk, tsk->parent); 1528 spin_unlock_irqrestore(&psig->siglock, flags); 1529 1530 return ret; 1531} 1532 1533static void do_notify_parent_cldstop(struct task_struct *tsk, int why) 1534{ 1535 struct siginfo info; 1536 unsigned long flags; 1537 struct task_struct *parent; 1538 struct sighand_struct *sighand; 1539 1540 if (task_ptrace(tsk)) 1541 parent = tsk->parent; 1542 else { 1543 tsk = tsk->group_leader; 1544 parent = tsk->real_parent; 1545 } 1546 1547 info.si_signo = SIGCHLD; 1548 info.si_errno = 0; 1549 /* 1550 * see comment in do_notify_parent() abot the following 3 lines 1551 */ 1552 rcu_read_lock(); 1553 info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns); 1554 info.si_uid = __task_cred(tsk)->uid; 1555 rcu_read_unlock(); 1556 1557 info.si_utime = cputime_to_clock_t(tsk->utime); 1558 info.si_stime = cputime_to_clock_t(tsk->stime); 1559 1560 info.si_code = why; 1561 switch (why) { 1562 case CLD_CONTINUED: 1563 info.si_status = SIGCONT; 1564 break; 1565 case CLD_STOPPED: 1566 info.si_status = tsk->signal->group_exit_code & 0x7f; 1567 break; 1568 case CLD_TRAPPED: 1569 info.si_status = tsk->exit_code & 0x7f; 1570 break; 1571 default: 1572 BUG(); 1573 } 1574 1575 sighand = parent->sighand; 1576 spin_lock_irqsave(&sighand->siglock, flags); 1577 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN && 1578 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP)) 1579 __group_send_sig_info(SIGCHLD, &info, parent); 1580 /* 1581 * Even if SIGCHLD is not generated, we must wake up wait4 calls. 1582 */ 1583 __wake_up_parent(tsk, parent); 1584 spin_unlock_irqrestore(&sighand->siglock, flags); 1585} 1586 1587static inline int may_ptrace_stop(void) 1588{ 1589 if (!likely(task_ptrace(current))) 1590 return 0; 1591 /* 1592 * Are we in the middle of do_coredump? 1593 * If so and our tracer is also part of the coredump stopping 1594 * is a deadlock situation, and pointless because our tracer 1595 * is dead so don't allow us to stop. 1596 * If SIGKILL was already sent before the caller unlocked 1597 * ->siglock we must see ->core_state != NULL. Otherwise it 1598 * is safe to enter schedule(). 1599 */ 1600 if (unlikely(current->mm->core_state) && 1601 unlikely(current->mm == current->parent->mm)) 1602 return 0; 1603 1604 return 1; 1605} 1606 1607/* 1608 * Return nonzero if there is a SIGKILL that should be waking us up. 1609 * Called with the siglock held. 1610 */ 1611static int sigkill_pending(struct task_struct *tsk) 1612{ 1613 return sigismember(&tsk->pending.signal, SIGKILL) || 1614 sigismember(&tsk->signal->shared_pending.signal, SIGKILL); 1615} 1616 1617/* 1618 * This must be called with current->sighand->siglock held. 1619 * 1620 * This should be the path for all ptrace stops. 1621 * We always set current->last_siginfo while stopped here. 1622 * That makes it a way to test a stopped process for 1623 * being ptrace-stopped vs being job-control-stopped. 1624 * 1625 * If we actually decide not to stop at all because the tracer 1626 * is gone, we keep current->exit_code unless clear_code. 1627 */ 1628static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info) 1629{ 1630 if (arch_ptrace_stop_needed(exit_code, info)) { 1631 /* 1632 * The arch code has something special to do before a 1633 * ptrace stop. This is allowed to block, e.g. for faults 1634 * on user stack pages. We can't keep the siglock while 1635 * calling arch_ptrace_stop, so we must release it now. 1636 * To preserve proper semantics, we must do this before 1637 * any signal bookkeeping like checking group_stop_count. 1638 * Meanwhile, a SIGKILL could come in before we retake the 1639 * siglock. That must prevent us from sleeping in TASK_TRACED. 1640 * So after regaining the lock, we must check for SIGKILL. 1641 */ 1642 spin_unlock_irq(¤t->sighand->siglock); 1643 arch_ptrace_stop(exit_code, info); 1644 spin_lock_irq(¤t->sighand->siglock); 1645 if (sigkill_pending(current)) 1646 return; 1647 } 1648 1649 /* 1650 * If there is a group stop in progress, 1651 * we must participate in the bookkeeping. 1652 */ 1653 if (current->signal->group_stop_count > 0) 1654 --current->signal->group_stop_count; 1655 1656 current->last_siginfo = info; 1657 current->exit_code = exit_code; 1658 1659 /* Let the debugger run. */ 1660 __set_current_state(TASK_TRACED); 1661 spin_unlock_irq(¤t->sighand->siglock); 1662 read_lock(&tasklist_lock); 1663 if (may_ptrace_stop()) { 1664 do_notify_parent_cldstop(current, CLD_TRAPPED); 1665 preempt_disable(); 1666 read_unlock(&tasklist_lock); 1667 preempt_enable_no_resched(); 1668 schedule(); 1669 } else { 1670 /* 1671 * By the time we got the lock, our tracer went away. 1672 * Don't drop the lock yet, another tracer may come. 1673 */ 1674 __set_current_state(TASK_RUNNING); 1675 if (clear_code) 1676 current->exit_code = 0; 1677 read_unlock(&tasklist_lock); 1678 } 1679 1680 /* 1681 * While in TASK_TRACED, we were considered "frozen enough". 1682 * Now that we woke up, it's crucial if we're supposed to be 1683 * frozen that we freeze now before running anything substantial. 1684 */ 1685 try_to_freeze(); 1686 1687 /* 1688 * We are back. Now reacquire the siglock before touching 1689 * last_siginfo, so that we are sure to have synchronized with 1690 * any signal-sending on another CPU that wants to examine it. 1691 */ 1692 spin_lock_irq(¤t->sighand->siglock); 1693 current->last_siginfo = NULL; 1694 1695 /* 1696 * Queued signals ignored us while we were stopped for tracing. 1697 * So check for any that we should take before resuming user mode. 1698 * This sets TIF_SIGPENDING, but never clears it. 1699 */ 1700 recalc_sigpending_tsk(current); 1701} 1702 1703void ptrace_notify(int exit_code) 1704{ 1705 siginfo_t info; 1706 1707 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP); 1708 1709 memset(&info, 0, sizeof info); 1710 info.si_signo = SIGTRAP; 1711 info.si_code = exit_code; 1712 info.si_pid = task_pid_vnr(current); 1713 info.si_uid = current_uid(); 1714 1715 /* Let the debugger run. */ 1716 spin_lock_irq(¤t->sighand->siglock); 1717 ptrace_stop(exit_code, 1, &info); 1718 spin_unlock_irq(¤t->sighand->siglock); 1719} 1720 1721/* 1722 * This performs the stopping for SIGSTOP and other stop signals. 1723 * We have to stop all threads in the thread group. 1724 * Returns nonzero if we've actually stopped and released the siglock. 1725 * Returns zero if we didn't stop and still hold the siglock. 1726 */ 1727static int do_signal_stop(int signr) 1728{ 1729 struct signal_struct *sig = current->signal; 1730 int notify; 1731 1732 if (!sig->group_stop_count) { 1733 struct task_struct *t; 1734 1735 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) || 1736 unlikely(signal_group_exit(sig))) 1737 return 0; 1738 /* 1739 * There is no group stop already in progress. 1740 * We must initiate one now. 1741 */ 1742 sig->group_exit_code = signr; 1743 1744 sig->group_stop_count = 1; 1745 for (t = next_thread(current); t != current; t = next_thread(t)) 1746 /* 1747 * Setting state to TASK_STOPPED for a group 1748 * stop is always done with the siglock held, 1749 * so this check has no races. 1750 */ 1751 if (!(t->flags & PF_EXITING) && 1752 !task_is_stopped_or_traced(t)) { 1753 sig->group_stop_count++; 1754 signal_wake_up(t, 0); 1755 } 1756 } 1757 /* 1758 * If there are no other threads in the group, or if there is 1759 * a group stop in progress and we are the last to stop, report 1760 * to the parent. When ptraced, every thread reports itself. 1761 */ 1762 notify = sig->group_stop_count == 1 ? CLD_STOPPED : 0; 1763 notify = tracehook_notify_jctl(notify, CLD_STOPPED); 1764 /* 1765 * tracehook_notify_jctl() can drop and reacquire siglock, so 1766 * we keep ->group_stop_count != 0 before the call. If SIGCONT 1767 * or SIGKILL comes in between ->group_stop_count == 0. 1768 */ 1769 if (sig->group_stop_count) { 1770 if (!--sig->group_stop_count) 1771 sig->flags = SIGNAL_STOP_STOPPED; 1772 current->exit_code = sig->group_exit_code; 1773 __set_current_state(TASK_STOPPED); 1774 } 1775 spin_unlock_irq(¤t->sighand->siglock); 1776 1777 if (notify) { 1778 read_lock(&tasklist_lock); 1779 do_notify_parent_cldstop(current, notify); 1780 read_unlock(&tasklist_lock); 1781 } 1782 1783 /* Now we don't run again until woken by SIGCONT or SIGKILL */ 1784 do { 1785 schedule(); 1786 } while (try_to_freeze()); 1787 1788 tracehook_finish_jctl(); 1789 current->exit_code = 0; 1790 1791 return 1; 1792} 1793 1794static int ptrace_signal(int signr, siginfo_t *info, 1795 struct pt_regs *regs, void *cookie) 1796{ 1797 if (!task_ptrace(current)) 1798 return signr; 1799 1800 ptrace_signal_deliver(regs, cookie); 1801 1802 /* Let the debugger run. */ 1803 ptrace_stop(signr, 0, info); 1804 1805 /* We're back. Did the debugger cancel the sig? */ 1806 signr = current->exit_code; 1807 if (signr == 0) 1808 return signr; 1809 1810 current->exit_code = 0; 1811 1812 /* Update the siginfo structure if the signal has 1813 changed. If the debugger wanted something 1814 specific in the siginfo structure then it should 1815 have updated *info via PTRACE_SETSIGINFO. */ 1816 if (signr != info->si_signo) { 1817 info->si_signo = signr; 1818 info->si_errno = 0; 1819 info->si_code = SI_USER; 1820 info->si_pid = task_pid_vnr(current->parent); 1821 info->si_uid = task_uid(current->parent); 1822 } 1823 1824 /* If the (new) signal is now blocked, requeue it. */ 1825 if (sigismember(¤t->blocked, signr)) { 1826 specific_send_sig_info(signr, info, current); 1827 signr = 0; 1828 } 1829 1830 return signr; 1831} 1832 1833int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka, 1834 struct pt_regs *regs, void *cookie) 1835{ 1836 struct sighand_struct *sighand = current->sighand; 1837 struct signal_struct *signal = current->signal; 1838 int signr; 1839 1840relock: 1841 /* 1842 * We'll jump back here after any time we were stopped in TASK_STOPPED. 1843 * While in TASK_STOPPED, we were considered "frozen enough". 1844 * Now that we woke up, it's crucial if we're supposed to be 1845 * frozen that we freeze now before running anything substantial. 1846 */ 1847 try_to_freeze(); 1848 1849 spin_lock_irq(&sighand->siglock); 1850 /* 1851 * Every stopped thread goes here after wakeup. Check to see if 1852 * we should notify the parent, prepare_signal(SIGCONT) encodes 1853 * the CLD_ si_code into SIGNAL_CLD_MASK bits. 1854 */ 1855 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) { 1856 int why = (signal->flags & SIGNAL_STOP_CONTINUED) 1857 ? CLD_CONTINUED : CLD_STOPPED; 1858 signal->flags &= ~SIGNAL_CLD_MASK; 1859 1860 why = tracehook_notify_jctl(why, CLD_CONTINUED); 1861 spin_unlock_irq(&sighand->siglock); 1862 1863 if (why) { 1864 read_lock(&tasklist_lock); 1865 do_notify_parent_cldstop(current->group_leader, why); 1866 read_unlock(&tasklist_lock); 1867 } 1868 goto relock; 1869 } 1870 1871 for (;;) { 1872 struct k_sigaction *ka; 1873 /* 1874 * Tracing can induce an artifical signal and choose sigaction. 1875 * The return value in @signr determines the default action, 1876 * but @info->si_signo is the signal number we will report. 1877 */ 1878 signr = tracehook_get_signal(current, regs, info, return_ka); 1879 if (unlikely(signr < 0)) 1880 goto relock; 1881 if (unlikely(signr != 0)) 1882 ka = return_ka; 1883 else { 1884 if (unlikely(signal->group_stop_count > 0) && 1885 do_signal_stop(0)) 1886 goto relock; 1887 1888 signr = dequeue_signal(current, ¤t->blocked, 1889 info); 1890 1891 if (!signr) 1892 break; /* will return 0 */ 1893 1894 if (signr != SIGKILL) { 1895 signr = ptrace_signal(signr, info, 1896 regs, cookie); 1897 if (!signr) 1898 continue; 1899 } 1900 1901 ka = &sighand->action[signr-1]; 1902 } 1903 1904 /* Trace actually delivered signals. */ 1905 trace_signal_deliver(signr, info, ka); 1906 1907 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */ 1908 continue; 1909 if (ka->sa.sa_handler != SIG_DFL) { 1910 /* Run the handler. */ 1911 *return_ka = *ka; 1912 1913 if (ka->sa.sa_flags & SA_ONESHOT) 1914 ka->sa.sa_handler = SIG_DFL; 1915 1916 break; /* will return non-zero "signr" value */ 1917 } 1918 1919 /* 1920 * Now we are doing the default action for this signal. 1921 */ 1922 if (sig_kernel_ignore(signr)) /* Default is nothing. */ 1923 continue; 1924 1925 /* 1926 * Global init gets no signals it doesn't want. 1927 * Container-init gets no signals it doesn't want from same 1928 * container. 1929 * 1930 * Note that if global/container-init sees a sig_kernel_only() 1931 * signal here, the signal must have been generated internally 1932 * or must have come from an ancestor namespace. In either 1933 * case, the signal cannot be dropped. 1934 */ 1935 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) && 1936 !sig_kernel_only(signr)) 1937 continue; 1938 1939 if (sig_kernel_stop(signr)) { 1940 /* 1941 * The default action is to stop all threads in 1942 * the thread group. The job control signals 1943 * do nothing in an orphaned pgrp, but SIGSTOP 1944 * always works. Note that siglock needs to be 1945 * dropped during the call to is_orphaned_pgrp() 1946 * because of lock ordering with tasklist_lock. 1947 * This allows an intervening SIGCONT to be posted. 1948 * We need to check for that and bail out if necessary. 1949 */ 1950 if (signr != SIGSTOP) { 1951 spin_unlock_irq(&sighand->siglock); 1952 1953 /* signals can be posted during this window */ 1954 1955 if (is_current_pgrp_orphaned()) 1956 goto relock; 1957 1958 spin_lock_irq(&sighand->siglock); 1959 } 1960 1961 if (likely(do_signal_stop(info->si_signo))) { 1962 /* It released the siglock. */ 1963 goto relock; 1964 } 1965 1966 /* 1967 * We didn't actually stop, due to a race 1968 * with SIGCONT or something like that. 1969 */ 1970 continue; 1971 } 1972 1973 spin_unlock_irq(&sighand->siglock); 1974 1975 /* 1976 * Anything else is fatal, maybe with a core dump. 1977 */ 1978 current->flags |= PF_SIGNALED; 1979 1980 if (sig_kernel_coredump(signr)) { 1981 if (print_fatal_signals) 1982 print_fatal_signal(regs, info->si_signo); 1983 /* 1984 * If it was able to dump core, this kills all 1985 * other threads in the group and synchronizes with 1986 * their demise. If we lost the race with another 1987 * thread getting here, it set group_exit_code 1988 * first and our do_group_exit call below will use 1989 * that value and ignore the one we pass it. 1990 */ 1991 do_coredump(info->si_signo, info->si_signo, regs); 1992 } 1993 1994 /* 1995 * Death signals, no core dump. 1996 */ 1997 do_group_exit(info->si_signo); 1998 /* NOTREACHED */ 1999 } 2000 spin_unlock_irq(&sighand->siglock); 2001 return signr; 2002} 2003 2004void exit_signals(struct task_struct *tsk) 2005{ 2006 int group_stop = 0; 2007 struct task_struct *t; 2008 2009 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) { 2010 tsk->flags |= PF_EXITING; 2011 return; 2012 } 2013 2014 spin_lock_irq(&tsk->sighand->siglock); 2015 /* 2016 * From now this task is not visible for group-wide signals, 2017 * see wants_signal(), do_signal_stop(). 2018 */ 2019 tsk->flags |= PF_EXITING; 2020 if (!signal_pending(tsk)) 2021 goto out; 2022 2023 /* It could be that __group_complete_signal() choose us to 2024 * notify about group-wide signal. Another thread should be 2025 * woken now to take the signal since we will not. 2026 */ 2027 for (t = tsk; (t = next_thread(t)) != tsk; ) 2028 if (!signal_pending(t) && !(t->flags & PF_EXITING)) 2029 recalc_sigpending_and_wake(t); 2030 2031 if (unlikely(tsk->signal->group_stop_count) && 2032 !--tsk->signal->group_stop_count) { 2033 tsk->signal->flags = SIGNAL_STOP_STOPPED; 2034 group_stop = tracehook_notify_jctl(CLD_STOPPED, CLD_STOPPED); 2035 } 2036out: 2037 spin_unlock_irq(&tsk->sighand->siglock); 2038 2039 if (unlikely(group_stop)) { 2040 read_lock(&tasklist_lock); 2041 do_notify_parent_cldstop(tsk, group_stop); 2042 read_unlock(&tasklist_lock); 2043 } 2044} 2045 2046EXPORT_SYMBOL(recalc_sigpending); 2047EXPORT_SYMBOL_GPL(dequeue_signal); 2048EXPORT_SYMBOL(flush_signals); 2049EXPORT_SYMBOL(force_sig); 2050EXPORT_SYMBOL(send_sig); 2051EXPORT_SYMBOL(send_sig_info); 2052EXPORT_SYMBOL(sigprocmask); 2053EXPORT_SYMBOL(block_all_signals); 2054EXPORT_SYMBOL(unblock_all_signals); 2055 2056 2057/* 2058 * System call entry points. 2059 */ 2060 2061SYSCALL_DEFINE0(restart_syscall) 2062{ 2063 struct restart_block *restart = ¤t_thread_info()->restart_block; 2064 return restart->fn(restart); 2065} 2066 2067long do_no_restart_syscall(struct restart_block *param) 2068{ 2069 return -EINTR; 2070} 2071 2072/* 2073 * We don't need to get the kernel lock - this is all local to this 2074 * particular thread.. (and that's good, because this is _heavily_ 2075 * used by various programs) 2076 */ 2077 2078/* 2079 * This is also useful for kernel threads that want to temporarily 2080 * (or permanently) block certain signals. 2081 * 2082 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel 2083 * interface happily blocks "unblockable" signals like SIGKILL 2084 * and friends. 2085 */ 2086int sigprocmask(int how, sigset_t *set, sigset_t *oldset) 2087{ 2088 int error; 2089 2090 spin_lock_irq(¤t->sighand->siglock); 2091 if (oldset) 2092 *oldset = current->blocked; 2093 2094 error = 0; 2095 switch (how) { 2096 case SIG_BLOCK: 2097 sigorsets(¤t->blocked, ¤t->blocked, set); 2098 break; 2099 case SIG_UNBLOCK: 2100 signandsets(¤t->blocked, ¤t->blocked, set); 2101 break; 2102 case SIG_SETMASK: 2103 current->blocked = *set; 2104 break; 2105 default: 2106 error = -EINVAL; 2107 } 2108 recalc_sigpending(); 2109 spin_unlock_irq(¤t->sighand->siglock); 2110 2111 return error; 2112} 2113 2114SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, set, 2115 sigset_t __user *, oset, size_t, sigsetsize) 2116{ 2117 int error = -EINVAL; 2118 sigset_t old_set, new_set; 2119 2120 if (sigsetsize != sizeof(sigset_t)) 2121 goto out; 2122 2123 if (set) { 2124 error = -EFAULT; 2125 if (copy_from_user(&new_set, set, sizeof(*set))) 2126 goto out; 2127 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); 2128 2129 error = sigprocmask(how, &new_set, &old_set); 2130 if (error) 2131 goto out; 2132 if (oset) 2133 goto set_old; 2134 } else if (oset) { 2135 spin_lock_irq(¤t->sighand->siglock); 2136 old_set = current->blocked; 2137 spin_unlock_irq(¤t->sighand->siglock); 2138 2139 set_old: 2140 error = -EFAULT; 2141 if (copy_to_user(oset, &old_set, sizeof(*oset))) 2142 goto out; 2143 } 2144 error = 0; 2145out: 2146 return error; 2147} 2148 2149long do_sigpending(void __user *set, unsigned long sigsetsize) 2150{ 2151 long error = -EINVAL; 2152 sigset_t pending; 2153 2154 if (sigsetsize > sizeof(sigset_t)) 2155 goto out; 2156 2157 spin_lock_irq(¤t->sighand->siglock); 2158 sigorsets(&pending, ¤t->pending.signal, 2159 ¤t->signal->shared_pending.signal); 2160 spin_unlock_irq(¤t->sighand->siglock); 2161 2162 /* Outside the lock because only this thread touches it. */ 2163 sigandsets(&pending, ¤t->blocked, &pending); 2164 2165 error = -EFAULT; 2166 if (!copy_to_user(set, &pending, sigsetsize)) 2167 error = 0; 2168 2169out: 2170 return error; 2171} 2172 2173SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize) 2174{ 2175 return do_sigpending(set, sigsetsize); 2176} 2177 2178#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER 2179 2180int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from) 2181{ 2182 int err; 2183 2184 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t))) 2185 return -EFAULT; 2186 if (from->si_code < 0) 2187 return __copy_to_user(to, from, sizeof(siginfo_t)) 2188 ? -EFAULT : 0; 2189 /* 2190 * If you change siginfo_t structure, please be sure 2191 * this code is fixed accordingly. 2192 * Please remember to update the signalfd_copyinfo() function 2193 * inside fs/signalfd.c too, in case siginfo_t changes. 2194 * It should never copy any pad contained in the structure 2195 * to avoid security leaks, but must copy the generic 2196 * 3 ints plus the relevant union member. 2197 */ 2198 err = __put_user(from->si_signo, &to->si_signo); 2199 err |= __put_user(from->si_errno, &to->si_errno); 2200 err |= __put_user((short)from->si_code, &to->si_code); 2201 switch (from->si_code & __SI_MASK) { 2202 case __SI_KILL: 2203 err |= __put_user(from->si_pid, &to->si_pid); 2204 err |= __put_user(from->si_uid, &to->si_uid); 2205 break; 2206 case __SI_TIMER: 2207 err |= __put_user(from->si_tid, &to->si_tid); 2208 err |= __put_user(from->si_overrun, &to->si_overrun); 2209 err |= __put_user(from->si_ptr, &to->si_ptr); 2210 break; 2211 case __SI_POLL: 2212 err |= __put_user(from->si_band, &to->si_band); 2213 err |= __put_user(from->si_fd, &to->si_fd); 2214 break; 2215 case __SI_FAULT: 2216 err |= __put_user(from->si_addr, &to->si_addr); 2217#ifdef __ARCH_SI_TRAPNO 2218 err |= __put_user(from->si_trapno, &to->si_trapno); 2219#endif 2220#ifdef BUS_MCEERR_AO 2221 /* 2222 * Other callers might not initialize the si_lsb field, 2223 * so check explicitely for the right codes here. 2224 */ 2225 if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO) 2226 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb); 2227#endif 2228 break; 2229 case __SI_CHLD: 2230 err |= __put_user(from->si_pid, &to->si_pid); 2231 err |= __put_user(from->si_uid, &to->si_uid); 2232 err |= __put_user(from->si_status, &to->si_status); 2233 err |= __put_user(from->si_utime, &to->si_utime); 2234 err |= __put_user(from->si_stime, &to->si_stime); 2235 break; 2236 case __SI_RT: /* This is not generated by the kernel as of now. */ 2237 case __SI_MESGQ: /* But this is */ 2238 err |= __put_user(from->si_pid, &to->si_pid); 2239 err |= __put_user(from->si_uid, &to->si_uid); 2240 err |= __put_user(from->si_ptr, &to->si_ptr); 2241 break; 2242 default: /* this is just in case for now ... */ 2243 err |= __put_user(from->si_pid, &to->si_pid); 2244 err |= __put_user(from->si_uid, &to->si_uid); 2245 break; 2246 } 2247 return err; 2248} 2249 2250#endif 2251 2252SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese, 2253 siginfo_t __user *, uinfo, const struct timespec __user *, uts, 2254 size_t, sigsetsize) 2255{ 2256 int ret, sig; 2257 sigset_t these; 2258 struct timespec ts; 2259 siginfo_t info; 2260 long timeout = 0; 2261 2262 if (sigsetsize != sizeof(sigset_t)) 2263 return -EINVAL; 2264 2265 if (copy_from_user(&these, uthese, sizeof(these))) 2266 return -EFAULT; 2267 2268 /* 2269 * Invert the set of allowed signals to get those we 2270 * want to block. 2271 */ 2272 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP)); 2273 signotset(&these); 2274 2275 if (uts) { 2276 if (copy_from_user(&ts, uts, sizeof(ts))) 2277 return -EFAULT; 2278 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0 2279 || ts.tv_sec < 0) 2280 return -EINVAL; 2281 } 2282 2283 spin_lock_irq(¤t->sighand->siglock); 2284 sig = dequeue_signal(current, &these, &info); 2285 if (!sig) { 2286 timeout = MAX_SCHEDULE_TIMEOUT; 2287 if (uts) 2288 timeout = (timespec_to_jiffies(&ts) 2289 + (ts.tv_sec || ts.tv_nsec)); 2290 2291 if (timeout) { 2292 /* None ready -- temporarily unblock those we're 2293 * interested while we are sleeping in so that we'll 2294 * be awakened when they arrive. */ 2295 current->real_blocked = current->blocked; 2296 sigandsets(¤t->blocked, ¤t->blocked, &these); 2297 recalc_sigpending(); 2298 spin_unlock_irq(¤t->sighand->siglock); 2299 2300 timeout = schedule_timeout_interruptible(timeout); 2301 2302 spin_lock_irq(¤t->sighand->siglock); 2303 sig = dequeue_signal(current, &these, &info); 2304 current->blocked = current->real_blocked; 2305 siginitset(¤t->real_blocked, 0); 2306 recalc_sigpending(); 2307 } 2308 } 2309 spin_unlock_irq(¤t->sighand->siglock); 2310 2311 if (sig) { 2312 ret = sig; 2313 if (uinfo) { 2314 if (copy_siginfo_to_user(uinfo, &info)) 2315 ret = -EFAULT; 2316 } 2317 } else { 2318 ret = -EAGAIN; 2319 if (timeout) 2320 ret = -EINTR; 2321 } 2322 2323 return ret; 2324} 2325 2326SYSCALL_DEFINE2(kill, pid_t, pid, int, sig) 2327{ 2328 struct siginfo info; 2329 2330 info.si_signo = sig; 2331 info.si_errno = 0; 2332 info.si_code = SI_USER; 2333 info.si_pid = task_tgid_vnr(current); 2334 info.si_uid = current_uid(); 2335 2336 return kill_something_info(sig, &info, pid); 2337} 2338 2339static int 2340do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info) 2341{ 2342 struct task_struct *p; 2343 int error = -ESRCH; 2344 2345 rcu_read_lock(); 2346 p = find_task_by_vpid(pid); 2347 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) { 2348 error = check_kill_permission(sig, info, p); 2349 /* 2350 * The null signal is a permissions and process existence 2351 * probe. No signal is actually delivered. 2352 */ 2353 if (!error && sig) { 2354 error = do_send_sig_info(sig, info, p, false); 2355 /* 2356 * If lock_task_sighand() failed we pretend the task 2357 * dies after receiving the signal. The window is tiny, 2358 * and the signal is private anyway. 2359 */ 2360 if (unlikely(error == -ESRCH)) 2361 error = 0; 2362 } 2363 } 2364 rcu_read_unlock(); 2365 2366 return error; 2367} 2368 2369static int do_tkill(pid_t tgid, pid_t pid, int sig) 2370{ 2371 struct siginfo info; 2372 2373 info.si_signo = sig; 2374 info.si_errno = 0; 2375 info.si_code = SI_TKILL; 2376 info.si_pid = task_tgid_vnr(current); 2377 info.si_uid = current_uid(); 2378 2379 return do_send_specific(tgid, pid, sig, &info); 2380} 2381 2382/** 2383 * sys_tgkill - send signal to one specific thread 2384 * @tgid: the thread group ID of the thread 2385 * @pid: the PID of the thread 2386 * @sig: signal to be sent 2387 * 2388 * This syscall also checks the @tgid and returns -ESRCH even if the PID 2389 * exists but it's not belonging to the target process anymore. This 2390 * method solves the problem of threads exiting and PIDs getting reused. 2391 */ 2392SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig) 2393{ 2394 /* This is only valid for single tasks */ 2395 if (pid <= 0 || tgid <= 0) 2396 return -EINVAL; 2397 2398 return do_tkill(tgid, pid, sig); 2399} 2400 2401/* 2402 * Send a signal to only one task, even if it's a CLONE_THREAD task. 2403 */ 2404SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig) 2405{ 2406 /* This is only valid for single tasks */ 2407 if (pid <= 0) 2408 return -EINVAL; 2409 2410 return do_tkill(0, pid, sig); 2411} 2412 2413SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig, 2414 siginfo_t __user *, uinfo) 2415{ 2416 siginfo_t info; 2417 2418 if (copy_from_user(&info, uinfo, sizeof(siginfo_t))) 2419 return -EFAULT; 2420 2421 /* Not even root can pretend to send signals from the kernel. 2422 Nor can they impersonate a kill(), which adds source info. */ 2423 if (info.si_code >= 0) 2424 return -EPERM; 2425 info.si_signo = sig; 2426 2427 /* POSIX.1b doesn't mention process groups. */ 2428 return kill_proc_info(sig, &info, pid); 2429} 2430 2431long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info) 2432{ 2433 /* This is only valid for single tasks */ 2434 if (pid <= 0 || tgid <= 0) 2435 return -EINVAL; 2436 2437 /* Not even root can pretend to send signals from the kernel. 2438 Nor can they impersonate a kill(), which adds source info. */ 2439 if (info->si_code >= 0) 2440 return -EPERM; 2441 info->si_signo = sig; 2442 2443 return do_send_specific(tgid, pid, sig, info); 2444} 2445 2446SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig, 2447 siginfo_t __user *, uinfo) 2448{ 2449 siginfo_t info; 2450 2451 if (copy_from_user(&info, uinfo, sizeof(siginfo_t))) 2452 return -EFAULT; 2453 2454 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info); 2455} 2456 2457int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) 2458{ 2459 struct task_struct *t = current; 2460 struct k_sigaction *k; 2461 sigset_t mask; 2462 2463 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig))) 2464 return -EINVAL; 2465 2466 k = &t->sighand->action[sig-1]; 2467 2468 spin_lock_irq(¤t->sighand->siglock); 2469 if (oact) 2470 *oact = *k; 2471 2472 if (act) { 2473 sigdelsetmask(&act->sa.sa_mask, 2474 sigmask(SIGKILL) | sigmask(SIGSTOP)); 2475 *k = *act; 2476 /* 2477 * POSIX 3.3.1.3: 2478 * "Setting a signal action to SIG_IGN for a signal that is 2479 * pending shall cause the pending signal to be discarded, 2480 * whether or not it is blocked." 2481 * 2482 * "Setting a signal action to SIG_DFL for a signal that is 2483 * pending and whose default action is to ignore the signal 2484 * (for example, SIGCHLD), shall cause the pending signal to 2485 * be discarded, whether or not it is blocked" 2486 */ 2487 if (sig_handler_ignored(sig_handler(t, sig), sig)) { 2488 sigemptyset(&mask); 2489 sigaddset(&mask, sig); 2490 rm_from_queue_full(&mask, &t->signal->shared_pending); 2491 do { 2492 rm_from_queue_full(&mask, &t->pending); 2493 t = next_thread(t); 2494 } while (t != current); 2495 } 2496 } 2497 2498 spin_unlock_irq(¤t->sighand->siglock); 2499 return 0; 2500} 2501 2502int 2503do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp) 2504{ 2505 stack_t oss; 2506 int error; 2507 2508 oss.ss_sp = (void __user *) current->sas_ss_sp; 2509 oss.ss_size = current->sas_ss_size; 2510 oss.ss_flags = sas_ss_flags(sp); 2511 2512 if (uss) { 2513 void __user *ss_sp; 2514 size_t ss_size; 2515 int ss_flags; 2516 2517 error = -EFAULT; 2518 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))) 2519 goto out; 2520 error = __get_user(ss_sp, &uss->ss_sp) | 2521 __get_user(ss_flags, &uss->ss_flags) | 2522 __get_user(ss_size, &uss->ss_size); 2523 if (error) 2524 goto out; 2525 2526 error = -EPERM; 2527 if (on_sig_stack(sp)) 2528 goto out; 2529 2530 error = -EINVAL; 2531 /* 2532 * 2533 * Note - this code used to test ss_flags incorrectly 2534 * old code may have been written using ss_flags==0 2535 * to mean ss_flags==SS_ONSTACK (as this was the only 2536 * way that worked) - this fix preserves that older 2537 * mechanism 2538 */ 2539 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0) 2540 goto out; 2541 2542 if (ss_flags == SS_DISABLE) { 2543 ss_size = 0; 2544 ss_sp = NULL; 2545 } else { 2546 error = -ENOMEM; 2547 if (ss_size < MINSIGSTKSZ) 2548 goto out; 2549 } 2550 2551 current->sas_ss_sp = (unsigned long) ss_sp; 2552 current->sas_ss_size = ss_size; 2553 } 2554 2555 error = 0; 2556 if (uoss) { 2557 error = -EFAULT; 2558 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss))) 2559 goto out; 2560 error = __put_user(oss.ss_sp, &uoss->ss_sp) | 2561 __put_user(oss.ss_size, &uoss->ss_size) | 2562 __put_user(oss.ss_flags, &uoss->ss_flags); 2563 } 2564 2565out: 2566 return error; 2567} 2568 2569#ifdef __ARCH_WANT_SYS_SIGPENDING 2570 2571SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set) 2572{ 2573 return do_sigpending(set, sizeof(*set)); 2574} 2575 2576#endif 2577 2578#ifdef __ARCH_WANT_SYS_SIGPROCMASK 2579/* Some platforms have their own version with special arguments others 2580 support only sys_rt_sigprocmask. */ 2581 2582SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, set, 2583 old_sigset_t __user *, oset) 2584{ 2585 int error; 2586 old_sigset_t old_set, new_set; 2587 2588 if (set) { 2589 error = -EFAULT; 2590 if (copy_from_user(&new_set, set, sizeof(*set))) 2591 goto out; 2592 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP)); 2593 2594 spin_lock_irq(¤t->sighand->siglock); 2595 old_set = current->blocked.sig[0]; 2596 2597 error = 0; 2598 switch (how) { 2599 default: 2600 error = -EINVAL; 2601 break; 2602 case SIG_BLOCK: 2603 sigaddsetmask(¤t->blocked, new_set); 2604 break; 2605 case SIG_UNBLOCK: 2606 sigdelsetmask(¤t->blocked, new_set); 2607 break; 2608 case SIG_SETMASK: 2609 current->blocked.sig[0] = new_set; 2610 break; 2611 } 2612 2613 recalc_sigpending(); 2614 spin_unlock_irq(¤t->sighand->siglock); 2615 if (error) 2616 goto out; 2617 if (oset) 2618 goto set_old; 2619 } else if (oset) { 2620 old_set = current->blocked.sig[0]; 2621 set_old: 2622 error = -EFAULT; 2623 if (copy_to_user(oset, &old_set, sizeof(*oset))) 2624 goto out; 2625 } 2626 error = 0; 2627out: 2628 return error; 2629} 2630#endif /* __ARCH_WANT_SYS_SIGPROCMASK */ 2631 2632#ifdef __ARCH_WANT_SYS_RT_SIGACTION 2633SYSCALL_DEFINE4(rt_sigaction, int, sig, 2634 const struct sigaction __user *, act, 2635 struct sigaction __user *, oact, 2636 size_t, sigsetsize) 2637{ 2638 struct k_sigaction new_sa, old_sa; 2639 int ret = -EINVAL; 2640 2641 if (sigsetsize != sizeof(sigset_t)) 2642 goto out; 2643 2644 if (act) { 2645 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa))) 2646 return -EFAULT; 2647 } 2648 2649 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL); 2650 2651 if (!ret && oact) { 2652 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa))) 2653 return -EFAULT; 2654 } 2655out: 2656 return ret; 2657} 2658#endif /* __ARCH_WANT_SYS_RT_SIGACTION */ 2659 2660#ifdef __ARCH_WANT_SYS_SGETMASK 2661 2662/* 2663 * For backwards compatibility. Functionality superseded by sigprocmask. 2664 */ 2665SYSCALL_DEFINE0(sgetmask) 2666{ 2667 /* SMP safe */ 2668 return current->blocked.sig[0]; 2669} 2670 2671SYSCALL_DEFINE1(ssetmask, int, newmask) 2672{ 2673 int old; 2674 2675 spin_lock_irq(¤t->sighand->siglock); 2676 old = current->blocked.sig[0]; 2677 2678 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)| 2679 sigmask(SIGSTOP))); 2680 recalc_sigpending(); 2681 spin_unlock_irq(¤t->sighand->siglock); 2682 2683 return old; 2684} 2685#endif /* __ARCH_WANT_SGETMASK */ 2686 2687#ifdef __ARCH_WANT_SYS_SIGNAL 2688/* 2689 * For backwards compatibility. Functionality superseded by sigaction. 2690 */ 2691SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler) 2692{ 2693 struct k_sigaction new_sa, old_sa; 2694 int ret; 2695 2696 new_sa.sa.sa_handler = handler; 2697 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK; 2698 sigemptyset(&new_sa.sa.sa_mask); 2699 2700 ret = do_sigaction(sig, &new_sa, &old_sa); 2701 2702 return ret ? ret : (unsigned long)old_sa.sa.sa_handler; 2703} 2704#endif /* __ARCH_WANT_SYS_SIGNAL */ 2705 2706#ifdef __ARCH_WANT_SYS_PAUSE 2707 2708SYSCALL_DEFINE0(pause) 2709{ 2710 current->state = TASK_INTERRUPTIBLE; 2711 schedule(); 2712 return -ERESTARTNOHAND; 2713} 2714 2715#endif 2716 2717#ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND 2718SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize) 2719{ 2720 sigset_t newset; 2721 2722 if (sigsetsize != sizeof(sigset_t)) 2723 return -EINVAL; 2724 2725 if (copy_from_user(&newset, unewset, sizeof(newset))) 2726 return -EFAULT; 2727 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP)); 2728 2729 spin_lock_irq(¤t->sighand->siglock); 2730 current->saved_sigmask = current->blocked; 2731 current->blocked = newset; 2732 recalc_sigpending(); 2733 spin_unlock_irq(¤t->sighand->siglock); 2734 2735 current->state = TASK_INTERRUPTIBLE; 2736 schedule(); 2737 set_restore_sigmask(); 2738 return -ERESTARTNOHAND; 2739} 2740#endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */ 2741 2742__attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma) 2743{ 2744 return NULL; 2745} 2746 2747void __init signals_init(void) 2748{ 2749 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC); 2750} 2751 2752#ifdef CONFIG_KGDB_KDB 2753#include <linux/kdb.h> 2754/* 2755 * kdb_send_sig_info - Allows kdb to send signals without exposing 2756 * signal internals. This function checks if the required locks are 2757 * available before calling the main signal code, to avoid kdb 2758 * deadlocks. 2759 */ 2760void 2761kdb_send_sig_info(struct task_struct *t, struct siginfo *info) 2762{ 2763 static struct task_struct *kdb_prev_t; 2764 int sig, new_t; 2765 if (!spin_trylock(&t->sighand->siglock)) { 2766 kdb_printf("Can't do kill command now.\n" 2767 "The sigmask lock is held somewhere else in " 2768 "kernel, try again later\n"); 2769 return; 2770 } 2771 spin_unlock(&t->sighand->siglock); 2772 new_t = kdb_prev_t != t; 2773 kdb_prev_t = t; 2774 if (t->state != TASK_RUNNING && new_t) { 2775 kdb_printf("Process is not RUNNING, sending a signal from " 2776 "kdb risks deadlock\n" 2777 "on the run queue locks. " 2778 "The signal has _not_ been sent.\n" 2779 "Reissue the kill command if you want to risk " 2780 "the deadlock.\n"); 2781 return; 2782 } 2783 sig = info->si_signo; 2784 if (send_sig_info(sig, info, t)) 2785 kdb_printf("Fail to deliver Signal %d to process %d.\n", 2786 sig, t->pid); 2787 else 2788 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid); 2789} 2790#endif /* CONFIG_KGDB_KDB */ 2791