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