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/export.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/coredump.h> 21 #include <linux/security.h> 22 #include <linux/syscalls.h> 23 #include <linux/ptrace.h> 24 #include <linux/signal.h> 25 #include <linux/signalfd.h> 26 #include <linux/ratelimit.h> 27 #include <linux/tracehook.h> 28 #include <linux/capability.h> 29 #include <linux/freezer.h> 30 #include <linux/pid_namespace.h> 31 #include <linux/nsproxy.h> 32 #include <linux/user_namespace.h> 33 #include <linux/uprobes.h> 34 #include <linux/compat.h> 35 #include <linux/cn_proc.h> 36 #include <linux/compiler.h> 37 38 #define CREATE_TRACE_POINTS 39 #include <trace/events/signal.h> 40 41 #include <asm/param.h> 42 #include <linux/uaccess.h> 43 #include <asm/unistd.h> 44 #include <asm/siginfo.h> 45 #include <asm/cacheflush.h> 46 #include "audit.h" /* audit_signal_info() */ 47 48 /* 49 * SLAB caches for signal bits. 50 */ 51 52 static struct kmem_cache *sigqueue_cachep; 53 54 int print_fatal_signals __read_mostly; 55 56 static void __user *sig_handler(struct task_struct *t, int sig) 57 { 58 return t->sighand->action[sig - 1].sa.sa_handler; 59 } 60 61 static int sig_handler_ignored(void __user *handler, int sig) 62 { 63 /* Is it explicitly or implicitly ignored? */ 64 return handler == SIG_IGN || 65 (handler == SIG_DFL && sig_kernel_ignore(sig)); 66 } 67 68 static int sig_task_ignored(struct task_struct *t, int sig, bool force) 69 { 70 void __user *handler; 71 72 handler = sig_handler(t, sig); 73 74 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) && 75 handler == SIG_DFL && !force) 76 return 1; 77 78 return sig_handler_ignored(handler, sig); 79 } 80 81 static int sig_ignored(struct task_struct *t, int sig, bool force) 82 { 83 /* 84 * Blocked signals are never ignored, since the 85 * signal handler may change by the time it is 86 * unblocked. 87 */ 88 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig)) 89 return 0; 90 91 if (!sig_task_ignored(t, sig, force)) 92 return 0; 93 94 /* 95 * Tracers may want to know about even ignored signals. 96 */ 97 return !t->ptrace; 98 } 99 100 /* 101 * Re-calculate pending state from the set of locally pending 102 * signals, globally pending signals, and blocked signals. 103 */ 104 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked) 105 { 106 unsigned long ready; 107 long i; 108 109 switch (_NSIG_WORDS) { 110 default: 111 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;) 112 ready |= signal->sig[i] &~ blocked->sig[i]; 113 break; 114 115 case 4: ready = signal->sig[3] &~ blocked->sig[3]; 116 ready |= signal->sig[2] &~ blocked->sig[2]; 117 ready |= signal->sig[1] &~ blocked->sig[1]; 118 ready |= signal->sig[0] &~ blocked->sig[0]; 119 break; 120 121 case 2: ready = signal->sig[1] &~ blocked->sig[1]; 122 ready |= signal->sig[0] &~ blocked->sig[0]; 123 break; 124 125 case 1: ready = signal->sig[0] &~ blocked->sig[0]; 126 } 127 return ready != 0; 128 } 129 130 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b)) 131 132 static int recalc_sigpending_tsk(struct task_struct *t) 133 { 134 if ((t->jobctl & JOBCTL_PENDING_MASK) || 135 PENDING(&t->pending, &t->blocked) || 136 PENDING(&t->signal->shared_pending, &t->blocked)) { 137 set_tsk_thread_flag(t, TIF_SIGPENDING); 138 return 1; 139 } 140 /* 141 * We must never clear the flag in another thread, or in current 142 * when it's possible the current syscall is returning -ERESTART*. 143 * So we don't clear it here, and only callers who know they should do. 144 */ 145 return 0; 146 } 147 148 /* 149 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up. 150 * This is superfluous when called on current, the wakeup is a harmless no-op. 151 */ 152 void recalc_sigpending_and_wake(struct task_struct *t) 153 { 154 if (recalc_sigpending_tsk(t)) 155 signal_wake_up(t, 0); 156 } 157 158 void recalc_sigpending(void) 159 { 160 if (!recalc_sigpending_tsk(current) && !freezing(current)) 161 clear_thread_flag(TIF_SIGPENDING); 162 163 } 164 165 /* Given the mask, find the first available signal that should be serviced. */ 166 167 #define SYNCHRONOUS_MASK \ 168 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \ 169 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS)) 170 171 int next_signal(struct sigpending *pending, sigset_t *mask) 172 { 173 unsigned long i, *s, *m, x; 174 int sig = 0; 175 176 s = pending->signal.sig; 177 m = mask->sig; 178 179 /* 180 * Handle the first word specially: it contains the 181 * synchronous signals that need to be dequeued first. 182 */ 183 x = *s &~ *m; 184 if (x) { 185 if (x & SYNCHRONOUS_MASK) 186 x &= SYNCHRONOUS_MASK; 187 sig = ffz(~x) + 1; 188 return sig; 189 } 190 191 switch (_NSIG_WORDS) { 192 default: 193 for (i = 1; i < _NSIG_WORDS; ++i) { 194 x = *++s &~ *++m; 195 if (!x) 196 continue; 197 sig = ffz(~x) + i*_NSIG_BPW + 1; 198 break; 199 } 200 break; 201 202 case 2: 203 x = s[1] &~ m[1]; 204 if (!x) 205 break; 206 sig = ffz(~x) + _NSIG_BPW + 1; 207 break; 208 209 case 1: 210 /* Nothing to do */ 211 break; 212 } 213 214 return sig; 215 } 216 217 static inline void print_dropped_signal(int sig) 218 { 219 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10); 220 221 if (!print_fatal_signals) 222 return; 223 224 if (!__ratelimit(&ratelimit_state)) 225 return; 226 227 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n", 228 current->comm, current->pid, sig); 229 } 230 231 /** 232 * task_set_jobctl_pending - set jobctl pending bits 233 * @task: target task 234 * @mask: pending bits to set 235 * 236 * Clear @mask from @task->jobctl. @mask must be subset of 237 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK | 238 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is 239 * cleared. If @task is already being killed or exiting, this function 240 * becomes noop. 241 * 242 * CONTEXT: 243 * Must be called with @task->sighand->siglock held. 244 * 245 * RETURNS: 246 * %true if @mask is set, %false if made noop because @task was dying. 247 */ 248 bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask) 249 { 250 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME | 251 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING)); 252 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK)); 253 254 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING))) 255 return false; 256 257 if (mask & JOBCTL_STOP_SIGMASK) 258 task->jobctl &= ~JOBCTL_STOP_SIGMASK; 259 260 task->jobctl |= mask; 261 return true; 262 } 263 264 /** 265 * task_clear_jobctl_trapping - clear jobctl trapping bit 266 * @task: target task 267 * 268 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED. 269 * Clear it and wake up the ptracer. Note that we don't need any further 270 * locking. @task->siglock guarantees that @task->parent points to the 271 * ptracer. 272 * 273 * CONTEXT: 274 * Must be called with @task->sighand->siglock held. 275 */ 276 void task_clear_jobctl_trapping(struct task_struct *task) 277 { 278 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) { 279 task->jobctl &= ~JOBCTL_TRAPPING; 280 smp_mb(); /* advised by wake_up_bit() */ 281 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT); 282 } 283 } 284 285 /** 286 * task_clear_jobctl_pending - clear jobctl pending bits 287 * @task: target task 288 * @mask: pending bits to clear 289 * 290 * Clear @mask from @task->jobctl. @mask must be subset of 291 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other 292 * STOP bits are cleared together. 293 * 294 * If clearing of @mask leaves no stop or trap pending, this function calls 295 * task_clear_jobctl_trapping(). 296 * 297 * CONTEXT: 298 * Must be called with @task->sighand->siglock held. 299 */ 300 void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask) 301 { 302 BUG_ON(mask & ~JOBCTL_PENDING_MASK); 303 304 if (mask & JOBCTL_STOP_PENDING) 305 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED; 306 307 task->jobctl &= ~mask; 308 309 if (!(task->jobctl & JOBCTL_PENDING_MASK)) 310 task_clear_jobctl_trapping(task); 311 } 312 313 /** 314 * task_participate_group_stop - participate in a group stop 315 * @task: task participating in a group stop 316 * 317 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop. 318 * Group stop states are cleared and the group stop count is consumed if 319 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group 320 * stop, the appropriate %SIGNAL_* flags are set. 321 * 322 * CONTEXT: 323 * Must be called with @task->sighand->siglock held. 324 * 325 * RETURNS: 326 * %true if group stop completion should be notified to the parent, %false 327 * otherwise. 328 */ 329 static bool task_participate_group_stop(struct task_struct *task) 330 { 331 struct signal_struct *sig = task->signal; 332 bool consume = task->jobctl & JOBCTL_STOP_CONSUME; 333 334 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING)); 335 336 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING); 337 338 if (!consume) 339 return false; 340 341 if (!WARN_ON_ONCE(sig->group_stop_count == 0)) 342 sig->group_stop_count--; 343 344 /* 345 * Tell the caller to notify completion iff we are entering into a 346 * fresh group stop. Read comment in do_signal_stop() for details. 347 */ 348 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) { 349 sig->flags = SIGNAL_STOP_STOPPED; 350 return true; 351 } 352 return false; 353 } 354 355 /* 356 * allocate a new signal queue record 357 * - this may be called without locks if and only if t == current, otherwise an 358 * appropriate lock must be held to stop the target task from exiting 359 */ 360 static struct sigqueue * 361 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit) 362 { 363 struct sigqueue *q = NULL; 364 struct user_struct *user; 365 366 /* 367 * Protect access to @t credentials. This can go away when all 368 * callers hold rcu read lock. 369 */ 370 rcu_read_lock(); 371 user = get_uid(__task_cred(t)->user); 372 atomic_inc(&user->sigpending); 373 rcu_read_unlock(); 374 375 if (override_rlimit || 376 atomic_read(&user->sigpending) <= 377 task_rlimit(t, RLIMIT_SIGPENDING)) { 378 q = kmem_cache_alloc(sigqueue_cachep, flags); 379 } else { 380 print_dropped_signal(sig); 381 } 382 383 if (unlikely(q == NULL)) { 384 atomic_dec(&user->sigpending); 385 free_uid(user); 386 } else { 387 INIT_LIST_HEAD(&q->list); 388 q->flags = 0; 389 q->user = user; 390 } 391 392 return q; 393 } 394 395 static void __sigqueue_free(struct sigqueue *q) 396 { 397 if (q->flags & SIGQUEUE_PREALLOC) 398 return; 399 atomic_dec(&q->user->sigpending); 400 free_uid(q->user); 401 kmem_cache_free(sigqueue_cachep, q); 402 } 403 404 void flush_sigqueue(struct sigpending *queue) 405 { 406 struct sigqueue *q; 407 408 sigemptyset(&queue->signal); 409 while (!list_empty(&queue->list)) { 410 q = list_entry(queue->list.next, struct sigqueue , list); 411 list_del_init(&q->list); 412 __sigqueue_free(q); 413 } 414 } 415 416 /* 417 * Flush all pending signals for this kthread. 418 */ 419 void flush_signals(struct task_struct *t) 420 { 421 unsigned long flags; 422 423 spin_lock_irqsave(&t->sighand->siglock, flags); 424 clear_tsk_thread_flag(t, TIF_SIGPENDING); 425 flush_sigqueue(&t->pending); 426 flush_sigqueue(&t->signal->shared_pending); 427 spin_unlock_irqrestore(&t->sighand->siglock, flags); 428 } 429 430 #ifdef CONFIG_POSIX_TIMERS 431 static void __flush_itimer_signals(struct sigpending *pending) 432 { 433 sigset_t signal, retain; 434 struct sigqueue *q, *n; 435 436 signal = pending->signal; 437 sigemptyset(&retain); 438 439 list_for_each_entry_safe(q, n, &pending->list, list) { 440 int sig = q->info.si_signo; 441 442 if (likely(q->info.si_code != SI_TIMER)) { 443 sigaddset(&retain, sig); 444 } else { 445 sigdelset(&signal, sig); 446 list_del_init(&q->list); 447 __sigqueue_free(q); 448 } 449 } 450 451 sigorsets(&pending->signal, &signal, &retain); 452 } 453 454 void flush_itimer_signals(void) 455 { 456 struct task_struct *tsk = current; 457 unsigned long flags; 458 459 spin_lock_irqsave(&tsk->sighand->siglock, flags); 460 __flush_itimer_signals(&tsk->pending); 461 __flush_itimer_signals(&tsk->signal->shared_pending); 462 spin_unlock_irqrestore(&tsk->sighand->siglock, flags); 463 } 464 #endif 465 466 void ignore_signals(struct task_struct *t) 467 { 468 int i; 469 470 for (i = 0; i < _NSIG; ++i) 471 t->sighand->action[i].sa.sa_handler = SIG_IGN; 472 473 flush_signals(t); 474 } 475 476 /* 477 * Flush all handlers for a task. 478 */ 479 480 void 481 flush_signal_handlers(struct task_struct *t, int force_default) 482 { 483 int i; 484 struct k_sigaction *ka = &t->sighand->action[0]; 485 for (i = _NSIG ; i != 0 ; i--) { 486 if (force_default || ka->sa.sa_handler != SIG_IGN) 487 ka->sa.sa_handler = SIG_DFL; 488 ka->sa.sa_flags = 0; 489 #ifdef __ARCH_HAS_SA_RESTORER 490 ka->sa.sa_restorer = NULL; 491 #endif 492 sigemptyset(&ka->sa.sa_mask); 493 ka++; 494 } 495 } 496 497 int unhandled_signal(struct task_struct *tsk, int sig) 498 { 499 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler; 500 if (is_global_init(tsk)) 501 return 1; 502 if (handler != SIG_IGN && handler != SIG_DFL) 503 return 0; 504 /* if ptraced, let the tracer determine */ 505 return !tsk->ptrace; 506 } 507 508 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info) 509 { 510 struct sigqueue *q, *first = NULL; 511 512 /* 513 * Collect the siginfo appropriate to this signal. Check if 514 * there is another siginfo for the same signal. 515 */ 516 list_for_each_entry(q, &list->list, list) { 517 if (q->info.si_signo == sig) { 518 if (first) 519 goto still_pending; 520 first = q; 521 } 522 } 523 524 sigdelset(&list->signal, sig); 525 526 if (first) { 527 still_pending: 528 list_del_init(&first->list); 529 copy_siginfo(info, &first->info); 530 __sigqueue_free(first); 531 } else { 532 /* 533 * Ok, it wasn't in the queue. This must be 534 * a fast-pathed signal or we must have been 535 * out of queue space. So zero out the info. 536 */ 537 info->si_signo = sig; 538 info->si_errno = 0; 539 info->si_code = SI_USER; 540 info->si_pid = 0; 541 info->si_uid = 0; 542 } 543 } 544 545 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask, 546 siginfo_t *info) 547 { 548 int sig = next_signal(pending, mask); 549 550 if (sig) 551 collect_signal(sig, pending, info); 552 return sig; 553 } 554 555 /* 556 * Dequeue a signal and return the element to the caller, which is 557 * expected to free it. 558 * 559 * All callers have to hold the siglock. 560 */ 561 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info) 562 { 563 int signr; 564 565 /* We only dequeue private signals from ourselves, we don't let 566 * signalfd steal them 567 */ 568 signr = __dequeue_signal(&tsk->pending, mask, info); 569 if (!signr) { 570 signr = __dequeue_signal(&tsk->signal->shared_pending, 571 mask, info); 572 #ifdef CONFIG_POSIX_TIMERS 573 /* 574 * itimer signal ? 575 * 576 * itimers are process shared and we restart periodic 577 * itimers in the signal delivery path to prevent DoS 578 * attacks in the high resolution timer case. This is 579 * compliant with the old way of self-restarting 580 * itimers, as the SIGALRM is a legacy signal and only 581 * queued once. Changing the restart behaviour to 582 * restart the timer in the signal dequeue path is 583 * reducing the timer noise on heavy loaded !highres 584 * systems too. 585 */ 586 if (unlikely(signr == SIGALRM)) { 587 struct hrtimer *tmr = &tsk->signal->real_timer; 588 589 if (!hrtimer_is_queued(tmr) && 590 tsk->signal->it_real_incr != 0) { 591 hrtimer_forward(tmr, tmr->base->get_time(), 592 tsk->signal->it_real_incr); 593 hrtimer_restart(tmr); 594 } 595 } 596 #endif 597 } 598 599 recalc_sigpending(); 600 if (!signr) 601 return 0; 602 603 if (unlikely(sig_kernel_stop(signr))) { 604 /* 605 * Set a marker that we have dequeued a stop signal. Our 606 * caller might release the siglock and then the pending 607 * stop signal it is about to process is no longer in the 608 * pending bitmasks, but must still be cleared by a SIGCONT 609 * (and overruled by a SIGKILL). So those cases clear this 610 * shared flag after we've set it. Note that this flag may 611 * remain set after the signal we return is ignored or 612 * handled. That doesn't matter because its only purpose 613 * is to alert stop-signal processing code when another 614 * processor has come along and cleared the flag. 615 */ 616 current->jobctl |= JOBCTL_STOP_DEQUEUED; 617 } 618 #ifdef CONFIG_POSIX_TIMERS 619 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) { 620 /* 621 * Release the siglock to ensure proper locking order 622 * of timer locks outside of siglocks. Note, we leave 623 * irqs disabled here, since the posix-timers code is 624 * about to disable them again anyway. 625 */ 626 spin_unlock(&tsk->sighand->siglock); 627 do_schedule_next_timer(info); 628 spin_lock(&tsk->sighand->siglock); 629 } 630 #endif 631 return signr; 632 } 633 634 /* 635 * Tell a process that it has a new active signal.. 636 * 637 * NOTE! we rely on the previous spin_lock to 638 * lock interrupts for us! We can only be called with 639 * "siglock" held, and the local interrupt must 640 * have been disabled when that got acquired! 641 * 642 * No need to set need_resched since signal event passing 643 * goes through ->blocked 644 */ 645 void signal_wake_up_state(struct task_struct *t, unsigned int state) 646 { 647 set_tsk_thread_flag(t, TIF_SIGPENDING); 648 /* 649 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable 650 * case. We don't check t->state here because there is a race with it 651 * executing another processor and just now entering stopped state. 652 * By using wake_up_state, we ensure the process will wake up and 653 * handle its death signal. 654 */ 655 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE)) 656 kick_process(t); 657 } 658 659 /* 660 * Remove signals in mask from the pending set and queue. 661 * Returns 1 if any signals were found. 662 * 663 * All callers must be holding the siglock. 664 */ 665 static int flush_sigqueue_mask(sigset_t *mask, struct sigpending *s) 666 { 667 struct sigqueue *q, *n; 668 sigset_t m; 669 670 sigandsets(&m, mask, &s->signal); 671 if (sigisemptyset(&m)) 672 return 0; 673 674 sigandnsets(&s->signal, &s->signal, mask); 675 list_for_each_entry_safe(q, n, &s->list, list) { 676 if (sigismember(mask, q->info.si_signo)) { 677 list_del_init(&q->list); 678 __sigqueue_free(q); 679 } 680 } 681 return 1; 682 } 683 684 static inline int is_si_special(const struct siginfo *info) 685 { 686 return info <= SEND_SIG_FORCED; 687 } 688 689 static inline bool si_fromuser(const struct siginfo *info) 690 { 691 return info == SEND_SIG_NOINFO || 692 (!is_si_special(info) && SI_FROMUSER(info)); 693 } 694 695 /* 696 * called with RCU read lock from check_kill_permission() 697 */ 698 static int kill_ok_by_cred(struct task_struct *t) 699 { 700 const struct cred *cred = current_cred(); 701 const struct cred *tcred = __task_cred(t); 702 703 if (uid_eq(cred->euid, tcred->suid) || 704 uid_eq(cred->euid, tcred->uid) || 705 uid_eq(cred->uid, tcred->suid) || 706 uid_eq(cred->uid, tcred->uid)) 707 return 1; 708 709 if (ns_capable(tcred->user_ns, CAP_KILL)) 710 return 1; 711 712 return 0; 713 } 714 715 /* 716 * Bad permissions for sending the signal 717 * - the caller must hold the RCU read lock 718 */ 719 static int check_kill_permission(int sig, struct siginfo *info, 720 struct task_struct *t) 721 { 722 struct pid *sid; 723 int error; 724 725 if (!valid_signal(sig)) 726 return -EINVAL; 727 728 if (!si_fromuser(info)) 729 return 0; 730 731 error = audit_signal_info(sig, t); /* Let audit system see the signal */ 732 if (error) 733 return error; 734 735 if (!same_thread_group(current, t) && 736 !kill_ok_by_cred(t)) { 737 switch (sig) { 738 case SIGCONT: 739 sid = task_session(t); 740 /* 741 * We don't return the error if sid == NULL. The 742 * task was unhashed, the caller must notice this. 743 */ 744 if (!sid || sid == task_session(current)) 745 break; 746 default: 747 return -EPERM; 748 } 749 } 750 751 return security_task_kill(t, info, sig, 0); 752 } 753 754 /** 755 * ptrace_trap_notify - schedule trap to notify ptracer 756 * @t: tracee wanting to notify tracer 757 * 758 * This function schedules sticky ptrace trap which is cleared on the next 759 * TRAP_STOP to notify ptracer of an event. @t must have been seized by 760 * ptracer. 761 * 762 * If @t is running, STOP trap will be taken. If trapped for STOP and 763 * ptracer is listening for events, tracee is woken up so that it can 764 * re-trap for the new event. If trapped otherwise, STOP trap will be 765 * eventually taken without returning to userland after the existing traps 766 * are finished by PTRACE_CONT. 767 * 768 * CONTEXT: 769 * Must be called with @task->sighand->siglock held. 770 */ 771 static void ptrace_trap_notify(struct task_struct *t) 772 { 773 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED)); 774 assert_spin_locked(&t->sighand->siglock); 775 776 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY); 777 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING); 778 } 779 780 /* 781 * Handle magic process-wide effects of stop/continue signals. Unlike 782 * the signal actions, these happen immediately at signal-generation 783 * time regardless of blocking, ignoring, or handling. This does the 784 * actual continuing for SIGCONT, but not the actual stopping for stop 785 * signals. The process stop is done as a signal action for SIG_DFL. 786 * 787 * Returns true if the signal should be actually delivered, otherwise 788 * it should be dropped. 789 */ 790 static bool prepare_signal(int sig, struct task_struct *p, bool force) 791 { 792 struct signal_struct *signal = p->signal; 793 struct task_struct *t; 794 sigset_t flush; 795 796 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) { 797 if (!(signal->flags & SIGNAL_GROUP_EXIT)) 798 return sig == SIGKILL; 799 /* 800 * The process is in the middle of dying, nothing to do. 801 */ 802 } else if (sig_kernel_stop(sig)) { 803 /* 804 * This is a stop signal. Remove SIGCONT from all queues. 805 */ 806 siginitset(&flush, sigmask(SIGCONT)); 807 flush_sigqueue_mask(&flush, &signal->shared_pending); 808 for_each_thread(p, t) 809 flush_sigqueue_mask(&flush, &t->pending); 810 } else if (sig == SIGCONT) { 811 unsigned int why; 812 /* 813 * Remove all stop signals from all queues, wake all threads. 814 */ 815 siginitset(&flush, SIG_KERNEL_STOP_MASK); 816 flush_sigqueue_mask(&flush, &signal->shared_pending); 817 for_each_thread(p, t) { 818 flush_sigqueue_mask(&flush, &t->pending); 819 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING); 820 if (likely(!(t->ptrace & PT_SEIZED))) 821 wake_up_state(t, __TASK_STOPPED); 822 else 823 ptrace_trap_notify(t); 824 } 825 826 /* 827 * Notify the parent with CLD_CONTINUED if we were stopped. 828 * 829 * If we were in the middle of a group stop, we pretend it 830 * was already finished, and then continued. Since SIGCHLD 831 * doesn't queue we report only CLD_STOPPED, as if the next 832 * CLD_CONTINUED was dropped. 833 */ 834 why = 0; 835 if (signal->flags & SIGNAL_STOP_STOPPED) 836 why |= SIGNAL_CLD_CONTINUED; 837 else if (signal->group_stop_count) 838 why |= SIGNAL_CLD_STOPPED; 839 840 if (why) { 841 /* 842 * The first thread which returns from do_signal_stop() 843 * will take ->siglock, notice SIGNAL_CLD_MASK, and 844 * notify its parent. See get_signal_to_deliver(). 845 */ 846 signal->flags = why | SIGNAL_STOP_CONTINUED; 847 signal->group_stop_count = 0; 848 signal->group_exit_code = 0; 849 } 850 } 851 852 return !sig_ignored(p, sig, force); 853 } 854 855 /* 856 * Test if P wants to take SIG. After we've checked all threads with this, 857 * it's equivalent to finding no threads not blocking SIG. Any threads not 858 * blocking SIG were ruled out because they are not running and already 859 * have pending signals. Such threads will dequeue from the shared queue 860 * as soon as they're available, so putting the signal on the shared queue 861 * will be equivalent to sending it to one such thread. 862 */ 863 static inline int wants_signal(int sig, struct task_struct *p) 864 { 865 if (sigismember(&p->blocked, sig)) 866 return 0; 867 if (p->flags & PF_EXITING) 868 return 0; 869 if (sig == SIGKILL) 870 return 1; 871 if (task_is_stopped_or_traced(p)) 872 return 0; 873 return task_curr(p) || !signal_pending(p); 874 } 875 876 static void complete_signal(int sig, struct task_struct *p, int group) 877 { 878 struct signal_struct *signal = p->signal; 879 struct task_struct *t; 880 881 /* 882 * Now find a thread we can wake up to take the signal off the queue. 883 * 884 * If the main thread wants the signal, it gets first crack. 885 * Probably the least surprising to the average bear. 886 */ 887 if (wants_signal(sig, p)) 888 t = p; 889 else if (!group || thread_group_empty(p)) 890 /* 891 * There is just one thread and it does not need to be woken. 892 * It will dequeue unblocked signals before it runs again. 893 */ 894 return; 895 else { 896 /* 897 * Otherwise try to find a suitable thread. 898 */ 899 t = signal->curr_target; 900 while (!wants_signal(sig, t)) { 901 t = next_thread(t); 902 if (t == signal->curr_target) 903 /* 904 * No thread needs to be woken. 905 * Any eligible threads will see 906 * the signal in the queue soon. 907 */ 908 return; 909 } 910 signal->curr_target = t; 911 } 912 913 /* 914 * Found a killable thread. If the signal will be fatal, 915 * then start taking the whole group down immediately. 916 */ 917 if (sig_fatal(p, sig) && 918 !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) && 919 !sigismember(&t->real_blocked, sig) && 920 (sig == SIGKILL || !t->ptrace)) { 921 /* 922 * This signal will be fatal to the whole group. 923 */ 924 if (!sig_kernel_coredump(sig)) { 925 /* 926 * Start a group exit and wake everybody up. 927 * This way we don't have other threads 928 * running and doing things after a slower 929 * thread has the fatal signal pending. 930 */ 931 signal->flags = SIGNAL_GROUP_EXIT; 932 signal->group_exit_code = sig; 933 signal->group_stop_count = 0; 934 t = p; 935 do { 936 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); 937 sigaddset(&t->pending.signal, SIGKILL); 938 signal_wake_up(t, 1); 939 } while_each_thread(p, t); 940 return; 941 } 942 } 943 944 /* 945 * The signal is already in the shared-pending queue. 946 * Tell the chosen thread to wake up and dequeue it. 947 */ 948 signal_wake_up(t, sig == SIGKILL); 949 return; 950 } 951 952 static inline int legacy_queue(struct sigpending *signals, int sig) 953 { 954 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig); 955 } 956 957 #ifdef CONFIG_USER_NS 958 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t) 959 { 960 if (current_user_ns() == task_cred_xxx(t, user_ns)) 961 return; 962 963 if (SI_FROMKERNEL(info)) 964 return; 965 966 rcu_read_lock(); 967 info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns), 968 make_kuid(current_user_ns(), info->si_uid)); 969 rcu_read_unlock(); 970 } 971 #else 972 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t) 973 { 974 return; 975 } 976 #endif 977 978 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, 979 int group, int from_ancestor_ns) 980 { 981 struct sigpending *pending; 982 struct sigqueue *q; 983 int override_rlimit; 984 int ret = 0, result; 985 986 assert_spin_locked(&t->sighand->siglock); 987 988 result = TRACE_SIGNAL_IGNORED; 989 if (!prepare_signal(sig, t, 990 from_ancestor_ns || (info == SEND_SIG_FORCED))) 991 goto ret; 992 993 pending = group ? &t->signal->shared_pending : &t->pending; 994 /* 995 * Short-circuit ignored signals and support queuing 996 * exactly one non-rt signal, so that we can get more 997 * detailed information about the cause of the signal. 998 */ 999 result = TRACE_SIGNAL_ALREADY_PENDING; 1000 if (legacy_queue(pending, sig)) 1001 goto ret; 1002 1003 result = TRACE_SIGNAL_DELIVERED; 1004 /* 1005 * fast-pathed signals for kernel-internal things like SIGSTOP 1006 * or SIGKILL. 1007 */ 1008 if (info == SEND_SIG_FORCED) 1009 goto out_set; 1010 1011 /* 1012 * Real-time signals must be queued if sent by sigqueue, or 1013 * some other real-time mechanism. It is implementation 1014 * defined whether kill() does so. We attempt to do so, on 1015 * the principle of least surprise, but since kill is not 1016 * allowed to fail with EAGAIN when low on memory we just 1017 * make sure at least one signal gets delivered and don't 1018 * pass on the info struct. 1019 */ 1020 if (sig < SIGRTMIN) 1021 override_rlimit = (is_si_special(info) || info->si_code >= 0); 1022 else 1023 override_rlimit = 0; 1024 1025 q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE, 1026 override_rlimit); 1027 if (q) { 1028 list_add_tail(&q->list, &pending->list); 1029 switch ((unsigned long) info) { 1030 case (unsigned long) SEND_SIG_NOINFO: 1031 q->info.si_signo = sig; 1032 q->info.si_errno = 0; 1033 q->info.si_code = SI_USER; 1034 q->info.si_pid = task_tgid_nr_ns(current, 1035 task_active_pid_ns(t)); 1036 q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid()); 1037 break; 1038 case (unsigned long) SEND_SIG_PRIV: 1039 q->info.si_signo = sig; 1040 q->info.si_errno = 0; 1041 q->info.si_code = SI_KERNEL; 1042 q->info.si_pid = 0; 1043 q->info.si_uid = 0; 1044 break; 1045 default: 1046 copy_siginfo(&q->info, info); 1047 if (from_ancestor_ns) 1048 q->info.si_pid = 0; 1049 break; 1050 } 1051 1052 userns_fixup_signal_uid(&q->info, t); 1053 1054 } else if (!is_si_special(info)) { 1055 if (sig >= SIGRTMIN && info->si_code != SI_USER) { 1056 /* 1057 * Queue overflow, abort. We may abort if the 1058 * signal was rt and sent by user using something 1059 * other than kill(). 1060 */ 1061 result = TRACE_SIGNAL_OVERFLOW_FAIL; 1062 ret = -EAGAIN; 1063 goto ret; 1064 } else { 1065 /* 1066 * This is a silent loss of information. We still 1067 * send the signal, but the *info bits are lost. 1068 */ 1069 result = TRACE_SIGNAL_LOSE_INFO; 1070 } 1071 } 1072 1073 out_set: 1074 signalfd_notify(t, sig); 1075 sigaddset(&pending->signal, sig); 1076 complete_signal(sig, t, group); 1077 ret: 1078 trace_signal_generate(sig, info, t, group, result); 1079 return ret; 1080 } 1081 1082 static int send_signal(int sig, struct siginfo *info, struct task_struct *t, 1083 int group) 1084 { 1085 int from_ancestor_ns = 0; 1086 1087 #ifdef CONFIG_PID_NS 1088 from_ancestor_ns = si_fromuser(info) && 1089 !task_pid_nr_ns(current, task_active_pid_ns(t)); 1090 #endif 1091 1092 return __send_signal(sig, info, t, group, from_ancestor_ns); 1093 } 1094 1095 static void print_fatal_signal(int signr) 1096 { 1097 struct pt_regs *regs = signal_pt_regs(); 1098 pr_info("potentially unexpected fatal signal %d.\n", signr); 1099 1100 #if defined(__i386__) && !defined(__arch_um__) 1101 pr_info("code at %08lx: ", regs->ip); 1102 { 1103 int i; 1104 for (i = 0; i < 16; i++) { 1105 unsigned char insn; 1106 1107 if (get_user(insn, (unsigned char *)(regs->ip + i))) 1108 break; 1109 pr_cont("%02x ", insn); 1110 } 1111 } 1112 pr_cont("\n"); 1113 #endif 1114 preempt_disable(); 1115 show_regs(regs); 1116 preempt_enable(); 1117 } 1118 1119 static int __init setup_print_fatal_signals(char *str) 1120 { 1121 get_option (&str, &print_fatal_signals); 1122 1123 return 1; 1124 } 1125 1126 __setup("print-fatal-signals=", setup_print_fatal_signals); 1127 1128 int 1129 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p) 1130 { 1131 return send_signal(sig, info, p, 1); 1132 } 1133 1134 static int 1135 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t) 1136 { 1137 return send_signal(sig, info, t, 0); 1138 } 1139 1140 int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p, 1141 bool group) 1142 { 1143 unsigned long flags; 1144 int ret = -ESRCH; 1145 1146 if (lock_task_sighand(p, &flags)) { 1147 ret = send_signal(sig, info, p, group); 1148 unlock_task_sighand(p, &flags); 1149 } 1150 1151 return ret; 1152 } 1153 1154 /* 1155 * Force a signal that the process can't ignore: if necessary 1156 * we unblock the signal and change any SIG_IGN to SIG_DFL. 1157 * 1158 * Note: If we unblock the signal, we always reset it to SIG_DFL, 1159 * since we do not want to have a signal handler that was blocked 1160 * be invoked when user space had explicitly blocked it. 1161 * 1162 * We don't want to have recursive SIGSEGV's etc, for example, 1163 * that is why we also clear SIGNAL_UNKILLABLE. 1164 */ 1165 int 1166 force_sig_info(int sig, struct siginfo *info, struct task_struct *t) 1167 { 1168 unsigned long int flags; 1169 int ret, blocked, ignored; 1170 struct k_sigaction *action; 1171 1172 spin_lock_irqsave(&t->sighand->siglock, flags); 1173 action = &t->sighand->action[sig-1]; 1174 ignored = action->sa.sa_handler == SIG_IGN; 1175 blocked = sigismember(&t->blocked, sig); 1176 if (blocked || ignored) { 1177 action->sa.sa_handler = SIG_DFL; 1178 if (blocked) { 1179 sigdelset(&t->blocked, sig); 1180 recalc_sigpending_and_wake(t); 1181 } 1182 } 1183 if (action->sa.sa_handler == SIG_DFL) 1184 t->signal->flags &= ~SIGNAL_UNKILLABLE; 1185 ret = specific_send_sig_info(sig, info, t); 1186 spin_unlock_irqrestore(&t->sighand->siglock, flags); 1187 1188 return ret; 1189 } 1190 1191 /* 1192 * Nuke all other threads in the group. 1193 */ 1194 int zap_other_threads(struct task_struct *p) 1195 { 1196 struct task_struct *t = p; 1197 int count = 0; 1198 1199 p->signal->group_stop_count = 0; 1200 1201 while_each_thread(p, t) { 1202 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); 1203 count++; 1204 1205 /* Don't bother with already dead threads */ 1206 if (t->exit_state) 1207 continue; 1208 sigaddset(&t->pending.signal, SIGKILL); 1209 signal_wake_up(t, 1); 1210 } 1211 1212 return count; 1213 } 1214 1215 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk, 1216 unsigned long *flags) 1217 { 1218 struct sighand_struct *sighand; 1219 1220 for (;;) { 1221 /* 1222 * Disable interrupts early to avoid deadlocks. 1223 * See rcu_read_unlock() comment header for details. 1224 */ 1225 local_irq_save(*flags); 1226 rcu_read_lock(); 1227 sighand = rcu_dereference(tsk->sighand); 1228 if (unlikely(sighand == NULL)) { 1229 rcu_read_unlock(); 1230 local_irq_restore(*flags); 1231 break; 1232 } 1233 /* 1234 * This sighand can be already freed and even reused, but 1235 * we rely on SLAB_DESTROY_BY_RCU and sighand_ctor() which 1236 * initializes ->siglock: this slab can't go away, it has 1237 * the same object type, ->siglock can't be reinitialized. 1238 * 1239 * We need to ensure that tsk->sighand is still the same 1240 * after we take the lock, we can race with de_thread() or 1241 * __exit_signal(). In the latter case the next iteration 1242 * must see ->sighand == NULL. 1243 */ 1244 spin_lock(&sighand->siglock); 1245 if (likely(sighand == tsk->sighand)) { 1246 rcu_read_unlock(); 1247 break; 1248 } 1249 spin_unlock(&sighand->siglock); 1250 rcu_read_unlock(); 1251 local_irq_restore(*flags); 1252 } 1253 1254 return sighand; 1255 } 1256 1257 /* 1258 * send signal info to all the members of a group 1259 */ 1260 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p) 1261 { 1262 int ret; 1263 1264 rcu_read_lock(); 1265 ret = check_kill_permission(sig, info, p); 1266 rcu_read_unlock(); 1267 1268 if (!ret && sig) 1269 ret = do_send_sig_info(sig, info, p, true); 1270 1271 return ret; 1272 } 1273 1274 /* 1275 * __kill_pgrp_info() sends a signal to a process group: this is what the tty 1276 * control characters do (^C, ^Z etc) 1277 * - the caller must hold at least a readlock on tasklist_lock 1278 */ 1279 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp) 1280 { 1281 struct task_struct *p = NULL; 1282 int retval, success; 1283 1284 success = 0; 1285 retval = -ESRCH; 1286 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 1287 int err = group_send_sig_info(sig, info, p); 1288 success |= !err; 1289 retval = err; 1290 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 1291 return success ? 0 : retval; 1292 } 1293 1294 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid) 1295 { 1296 int error = -ESRCH; 1297 struct task_struct *p; 1298 1299 for (;;) { 1300 rcu_read_lock(); 1301 p = pid_task(pid, PIDTYPE_PID); 1302 if (p) 1303 error = group_send_sig_info(sig, info, p); 1304 rcu_read_unlock(); 1305 if (likely(!p || error != -ESRCH)) 1306 return error; 1307 1308 /* 1309 * The task was unhashed in between, try again. If it 1310 * is dead, pid_task() will return NULL, if we race with 1311 * de_thread() it will find the new leader. 1312 */ 1313 } 1314 } 1315 1316 int kill_proc_info(int sig, struct siginfo *info, pid_t pid) 1317 { 1318 int error; 1319 rcu_read_lock(); 1320 error = kill_pid_info(sig, info, find_vpid(pid)); 1321 rcu_read_unlock(); 1322 return error; 1323 } 1324 1325 static int kill_as_cred_perm(const struct cred *cred, 1326 struct task_struct *target) 1327 { 1328 const struct cred *pcred = __task_cred(target); 1329 if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) && 1330 !uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid)) 1331 return 0; 1332 return 1; 1333 } 1334 1335 /* like kill_pid_info(), but doesn't use uid/euid of "current" */ 1336 int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid, 1337 const struct cred *cred, u32 secid) 1338 { 1339 int ret = -EINVAL; 1340 struct task_struct *p; 1341 unsigned long flags; 1342 1343 if (!valid_signal(sig)) 1344 return ret; 1345 1346 rcu_read_lock(); 1347 p = pid_task(pid, PIDTYPE_PID); 1348 if (!p) { 1349 ret = -ESRCH; 1350 goto out_unlock; 1351 } 1352 if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) { 1353 ret = -EPERM; 1354 goto out_unlock; 1355 } 1356 ret = security_task_kill(p, info, sig, secid); 1357 if (ret) 1358 goto out_unlock; 1359 1360 if (sig) { 1361 if (lock_task_sighand(p, &flags)) { 1362 ret = __send_signal(sig, info, p, 1, 0); 1363 unlock_task_sighand(p, &flags); 1364 } else 1365 ret = -ESRCH; 1366 } 1367 out_unlock: 1368 rcu_read_unlock(); 1369 return ret; 1370 } 1371 EXPORT_SYMBOL_GPL(kill_pid_info_as_cred); 1372 1373 /* 1374 * kill_something_info() interprets pid in interesting ways just like kill(2). 1375 * 1376 * POSIX specifies that kill(-1,sig) is unspecified, but what we have 1377 * is probably wrong. Should make it like BSD or SYSV. 1378 */ 1379 1380 static int kill_something_info(int sig, struct siginfo *info, pid_t pid) 1381 { 1382 int ret; 1383 1384 if (pid > 0) { 1385 rcu_read_lock(); 1386 ret = kill_pid_info(sig, info, find_vpid(pid)); 1387 rcu_read_unlock(); 1388 return ret; 1389 } 1390 1391 read_lock(&tasklist_lock); 1392 if (pid != -1) { 1393 ret = __kill_pgrp_info(sig, info, 1394 pid ? find_vpid(-pid) : task_pgrp(current)); 1395 } else { 1396 int retval = 0, count = 0; 1397 struct task_struct * p; 1398 1399 for_each_process(p) { 1400 if (task_pid_vnr(p) > 1 && 1401 !same_thread_group(p, current)) { 1402 int err = group_send_sig_info(sig, info, p); 1403 ++count; 1404 if (err != -EPERM) 1405 retval = err; 1406 } 1407 } 1408 ret = count ? retval : -ESRCH; 1409 } 1410 read_unlock(&tasklist_lock); 1411 1412 return ret; 1413 } 1414 1415 /* 1416 * These are for backward compatibility with the rest of the kernel source. 1417 */ 1418 1419 int send_sig_info(int sig, struct siginfo *info, struct task_struct *p) 1420 { 1421 /* 1422 * Make sure legacy kernel users don't send in bad values 1423 * (normal paths check this in check_kill_permission). 1424 */ 1425 if (!valid_signal(sig)) 1426 return -EINVAL; 1427 1428 return do_send_sig_info(sig, info, p, false); 1429 } 1430 1431 #define __si_special(priv) \ 1432 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO) 1433 1434 int 1435 send_sig(int sig, struct task_struct *p, int priv) 1436 { 1437 return send_sig_info(sig, __si_special(priv), p); 1438 } 1439 1440 void 1441 force_sig(int sig, struct task_struct *p) 1442 { 1443 force_sig_info(sig, SEND_SIG_PRIV, p); 1444 } 1445 1446 /* 1447 * When things go south during signal handling, we 1448 * will force a SIGSEGV. And if the signal that caused 1449 * the problem was already a SIGSEGV, we'll want to 1450 * make sure we don't even try to deliver the signal.. 1451 */ 1452 int 1453 force_sigsegv(int sig, struct task_struct *p) 1454 { 1455 if (sig == SIGSEGV) { 1456 unsigned long flags; 1457 spin_lock_irqsave(&p->sighand->siglock, flags); 1458 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL; 1459 spin_unlock_irqrestore(&p->sighand->siglock, flags); 1460 } 1461 force_sig(SIGSEGV, p); 1462 return 0; 1463 } 1464 1465 int kill_pgrp(struct pid *pid, int sig, int priv) 1466 { 1467 int ret; 1468 1469 read_lock(&tasklist_lock); 1470 ret = __kill_pgrp_info(sig, __si_special(priv), pid); 1471 read_unlock(&tasklist_lock); 1472 1473 return ret; 1474 } 1475 EXPORT_SYMBOL(kill_pgrp); 1476 1477 int kill_pid(struct pid *pid, int sig, int priv) 1478 { 1479 return kill_pid_info(sig, __si_special(priv), pid); 1480 } 1481 EXPORT_SYMBOL(kill_pid); 1482 1483 /* 1484 * These functions support sending signals using preallocated sigqueue 1485 * structures. This is needed "because realtime applications cannot 1486 * afford to lose notifications of asynchronous events, like timer 1487 * expirations or I/O completions". In the case of POSIX Timers 1488 * we allocate the sigqueue structure from the timer_create. If this 1489 * allocation fails we are able to report the failure to the application 1490 * with an EAGAIN error. 1491 */ 1492 struct sigqueue *sigqueue_alloc(void) 1493 { 1494 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0); 1495 1496 if (q) 1497 q->flags |= SIGQUEUE_PREALLOC; 1498 1499 return q; 1500 } 1501 1502 void sigqueue_free(struct sigqueue *q) 1503 { 1504 unsigned long flags; 1505 spinlock_t *lock = ¤t->sighand->siglock; 1506 1507 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); 1508 /* 1509 * We must hold ->siglock while testing q->list 1510 * to serialize with collect_signal() or with 1511 * __exit_signal()->flush_sigqueue(). 1512 */ 1513 spin_lock_irqsave(lock, flags); 1514 q->flags &= ~SIGQUEUE_PREALLOC; 1515 /* 1516 * If it is queued it will be freed when dequeued, 1517 * like the "regular" sigqueue. 1518 */ 1519 if (!list_empty(&q->list)) 1520 q = NULL; 1521 spin_unlock_irqrestore(lock, flags); 1522 1523 if (q) 1524 __sigqueue_free(q); 1525 } 1526 1527 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group) 1528 { 1529 int sig = q->info.si_signo; 1530 struct sigpending *pending; 1531 unsigned long flags; 1532 int ret, result; 1533 1534 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); 1535 1536 ret = -1; 1537 if (!likely(lock_task_sighand(t, &flags))) 1538 goto ret; 1539 1540 ret = 1; /* the signal is ignored */ 1541 result = TRACE_SIGNAL_IGNORED; 1542 if (!prepare_signal(sig, t, false)) 1543 goto out; 1544 1545 ret = 0; 1546 if (unlikely(!list_empty(&q->list))) { 1547 /* 1548 * If an SI_TIMER entry is already queue just increment 1549 * the overrun count. 1550 */ 1551 BUG_ON(q->info.si_code != SI_TIMER); 1552 q->info.si_overrun++; 1553 result = TRACE_SIGNAL_ALREADY_PENDING; 1554 goto out; 1555 } 1556 q->info.si_overrun = 0; 1557 1558 signalfd_notify(t, sig); 1559 pending = group ? &t->signal->shared_pending : &t->pending; 1560 list_add_tail(&q->list, &pending->list); 1561 sigaddset(&pending->signal, sig); 1562 complete_signal(sig, t, group); 1563 result = TRACE_SIGNAL_DELIVERED; 1564 out: 1565 trace_signal_generate(sig, &q->info, t, group, result); 1566 unlock_task_sighand(t, &flags); 1567 ret: 1568 return ret; 1569 } 1570 1571 /* 1572 * Let a parent know about the death of a child. 1573 * For a stopped/continued status change, use do_notify_parent_cldstop instead. 1574 * 1575 * Returns true if our parent ignored us and so we've switched to 1576 * self-reaping. 1577 */ 1578 bool do_notify_parent(struct task_struct *tsk, int sig) 1579 { 1580 struct siginfo info; 1581 unsigned long flags; 1582 struct sighand_struct *psig; 1583 bool autoreap = false; 1584 cputime_t utime, stime; 1585 1586 BUG_ON(sig == -1); 1587 1588 /* do_notify_parent_cldstop should have been called instead. */ 1589 BUG_ON(task_is_stopped_or_traced(tsk)); 1590 1591 BUG_ON(!tsk->ptrace && 1592 (tsk->group_leader != tsk || !thread_group_empty(tsk))); 1593 1594 if (sig != SIGCHLD) { 1595 /* 1596 * This is only possible if parent == real_parent. 1597 * Check if it has changed security domain. 1598 */ 1599 if (tsk->parent_exec_id != tsk->parent->self_exec_id) 1600 sig = SIGCHLD; 1601 } 1602 1603 info.si_signo = sig; 1604 info.si_errno = 0; 1605 /* 1606 * We are under tasklist_lock here so our parent is tied to 1607 * us and cannot change. 1608 * 1609 * task_active_pid_ns will always return the same pid namespace 1610 * until a task passes through release_task. 1611 * 1612 * write_lock() currently calls preempt_disable() which is the 1613 * same as rcu_read_lock(), but according to Oleg, this is not 1614 * correct to rely on this 1615 */ 1616 rcu_read_lock(); 1617 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent)); 1618 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns), 1619 task_uid(tsk)); 1620 rcu_read_unlock(); 1621 1622 task_cputime(tsk, &utime, &stime); 1623 info.si_utime = cputime_to_clock_t(utime + tsk->signal->utime); 1624 info.si_stime = cputime_to_clock_t(stime + tsk->signal->stime); 1625 1626 info.si_status = tsk->exit_code & 0x7f; 1627 if (tsk->exit_code & 0x80) 1628 info.si_code = CLD_DUMPED; 1629 else if (tsk->exit_code & 0x7f) 1630 info.si_code = CLD_KILLED; 1631 else { 1632 info.si_code = CLD_EXITED; 1633 info.si_status = tsk->exit_code >> 8; 1634 } 1635 1636 psig = tsk->parent->sighand; 1637 spin_lock_irqsave(&psig->siglock, flags); 1638 if (!tsk->ptrace && sig == SIGCHLD && 1639 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN || 1640 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) { 1641 /* 1642 * We are exiting and our parent doesn't care. POSIX.1 1643 * defines special semantics for setting SIGCHLD to SIG_IGN 1644 * or setting the SA_NOCLDWAIT flag: we should be reaped 1645 * automatically and not left for our parent's wait4 call. 1646 * Rather than having the parent do it as a magic kind of 1647 * signal handler, we just set this to tell do_exit that we 1648 * can be cleaned up without becoming a zombie. Note that 1649 * we still call __wake_up_parent in this case, because a 1650 * blocked sys_wait4 might now return -ECHILD. 1651 * 1652 * Whether we send SIGCHLD or not for SA_NOCLDWAIT 1653 * is implementation-defined: we do (if you don't want 1654 * it, just use SIG_IGN instead). 1655 */ 1656 autoreap = true; 1657 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) 1658 sig = 0; 1659 } 1660 if (valid_signal(sig) && sig) 1661 __group_send_sig_info(sig, &info, tsk->parent); 1662 __wake_up_parent(tsk, tsk->parent); 1663 spin_unlock_irqrestore(&psig->siglock, flags); 1664 1665 return autoreap; 1666 } 1667 1668 /** 1669 * do_notify_parent_cldstop - notify parent of stopped/continued state change 1670 * @tsk: task reporting the state change 1671 * @for_ptracer: the notification is for ptracer 1672 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report 1673 * 1674 * Notify @tsk's parent that the stopped/continued state has changed. If 1675 * @for_ptracer is %false, @tsk's group leader notifies to its real parent. 1676 * If %true, @tsk reports to @tsk->parent which should be the ptracer. 1677 * 1678 * CONTEXT: 1679 * Must be called with tasklist_lock at least read locked. 1680 */ 1681 static void do_notify_parent_cldstop(struct task_struct *tsk, 1682 bool for_ptracer, int why) 1683 { 1684 struct siginfo info; 1685 unsigned long flags; 1686 struct task_struct *parent; 1687 struct sighand_struct *sighand; 1688 cputime_t utime, stime; 1689 1690 if (for_ptracer) { 1691 parent = tsk->parent; 1692 } else { 1693 tsk = tsk->group_leader; 1694 parent = tsk->real_parent; 1695 } 1696 1697 info.si_signo = SIGCHLD; 1698 info.si_errno = 0; 1699 /* 1700 * see comment in do_notify_parent() about the following 4 lines 1701 */ 1702 rcu_read_lock(); 1703 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent)); 1704 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk)); 1705 rcu_read_unlock(); 1706 1707 task_cputime(tsk, &utime, &stime); 1708 info.si_utime = cputime_to_clock_t(utime); 1709 info.si_stime = cputime_to_clock_t(stime); 1710 1711 info.si_code = why; 1712 switch (why) { 1713 case CLD_CONTINUED: 1714 info.si_status = SIGCONT; 1715 break; 1716 case CLD_STOPPED: 1717 info.si_status = tsk->signal->group_exit_code & 0x7f; 1718 break; 1719 case CLD_TRAPPED: 1720 info.si_status = tsk->exit_code & 0x7f; 1721 break; 1722 default: 1723 BUG(); 1724 } 1725 1726 sighand = parent->sighand; 1727 spin_lock_irqsave(&sighand->siglock, flags); 1728 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN && 1729 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP)) 1730 __group_send_sig_info(SIGCHLD, &info, parent); 1731 /* 1732 * Even if SIGCHLD is not generated, we must wake up wait4 calls. 1733 */ 1734 __wake_up_parent(tsk, parent); 1735 spin_unlock_irqrestore(&sighand->siglock, flags); 1736 } 1737 1738 static inline int may_ptrace_stop(void) 1739 { 1740 if (!likely(current->ptrace)) 1741 return 0; 1742 /* 1743 * Are we in the middle of do_coredump? 1744 * If so and our tracer is also part of the coredump stopping 1745 * is a deadlock situation, and pointless because our tracer 1746 * is dead so don't allow us to stop. 1747 * If SIGKILL was already sent before the caller unlocked 1748 * ->siglock we must see ->core_state != NULL. Otherwise it 1749 * is safe to enter schedule(). 1750 * 1751 * This is almost outdated, a task with the pending SIGKILL can't 1752 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported 1753 * after SIGKILL was already dequeued. 1754 */ 1755 if (unlikely(current->mm->core_state) && 1756 unlikely(current->mm == current->parent->mm)) 1757 return 0; 1758 1759 return 1; 1760 } 1761 1762 /* 1763 * Return non-zero if there is a SIGKILL that should be waking us up. 1764 * Called with the siglock held. 1765 */ 1766 static int sigkill_pending(struct task_struct *tsk) 1767 { 1768 return sigismember(&tsk->pending.signal, SIGKILL) || 1769 sigismember(&tsk->signal->shared_pending.signal, SIGKILL); 1770 } 1771 1772 /* 1773 * This must be called with current->sighand->siglock held. 1774 * 1775 * This should be the path for all ptrace stops. 1776 * We always set current->last_siginfo while stopped here. 1777 * That makes it a way to test a stopped process for 1778 * being ptrace-stopped vs being job-control-stopped. 1779 * 1780 * If we actually decide not to stop at all because the tracer 1781 * is gone, we keep current->exit_code unless clear_code. 1782 */ 1783 static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info) 1784 __releases(¤t->sighand->siglock) 1785 __acquires(¤t->sighand->siglock) 1786 { 1787 bool gstop_done = false; 1788 1789 if (arch_ptrace_stop_needed(exit_code, info)) { 1790 /* 1791 * The arch code has something special to do before a 1792 * ptrace stop. This is allowed to block, e.g. for faults 1793 * on user stack pages. We can't keep the siglock while 1794 * calling arch_ptrace_stop, so we must release it now. 1795 * To preserve proper semantics, we must do this before 1796 * any signal bookkeeping like checking group_stop_count. 1797 * Meanwhile, a SIGKILL could come in before we retake the 1798 * siglock. That must prevent us from sleeping in TASK_TRACED. 1799 * So after regaining the lock, we must check for SIGKILL. 1800 */ 1801 spin_unlock_irq(¤t->sighand->siglock); 1802 arch_ptrace_stop(exit_code, info); 1803 spin_lock_irq(¤t->sighand->siglock); 1804 if (sigkill_pending(current)) 1805 return; 1806 } 1807 1808 /* 1809 * We're committing to trapping. TRACED should be visible before 1810 * TRAPPING is cleared; otherwise, the tracer might fail do_wait(). 1811 * Also, transition to TRACED and updates to ->jobctl should be 1812 * atomic with respect to siglock and should be done after the arch 1813 * hook as siglock is released and regrabbed across it. 1814 */ 1815 set_current_state(TASK_TRACED); 1816 1817 current->last_siginfo = info; 1818 current->exit_code = exit_code; 1819 1820 /* 1821 * If @why is CLD_STOPPED, we're trapping to participate in a group 1822 * stop. Do the bookkeeping. Note that if SIGCONT was delievered 1823 * across siglock relocks since INTERRUPT was scheduled, PENDING 1824 * could be clear now. We act as if SIGCONT is received after 1825 * TASK_TRACED is entered - ignore it. 1826 */ 1827 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING)) 1828 gstop_done = task_participate_group_stop(current); 1829 1830 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */ 1831 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP); 1832 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP) 1833 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY); 1834 1835 /* entering a trap, clear TRAPPING */ 1836 task_clear_jobctl_trapping(current); 1837 1838 spin_unlock_irq(¤t->sighand->siglock); 1839 read_lock(&tasklist_lock); 1840 if (may_ptrace_stop()) { 1841 /* 1842 * Notify parents of the stop. 1843 * 1844 * While ptraced, there are two parents - the ptracer and 1845 * the real_parent of the group_leader. The ptracer should 1846 * know about every stop while the real parent is only 1847 * interested in the completion of group stop. The states 1848 * for the two don't interact with each other. Notify 1849 * separately unless they're gonna be duplicates. 1850 */ 1851 do_notify_parent_cldstop(current, true, why); 1852 if (gstop_done && ptrace_reparented(current)) 1853 do_notify_parent_cldstop(current, false, why); 1854 1855 /* 1856 * Don't want to allow preemption here, because 1857 * sys_ptrace() needs this task to be inactive. 1858 * 1859 * XXX: implement read_unlock_no_resched(). 1860 */ 1861 preempt_disable(); 1862 read_unlock(&tasklist_lock); 1863 preempt_enable_no_resched(); 1864 freezable_schedule(); 1865 } else { 1866 /* 1867 * By the time we got the lock, our tracer went away. 1868 * Don't drop the lock yet, another tracer may come. 1869 * 1870 * If @gstop_done, the ptracer went away between group stop 1871 * completion and here. During detach, it would have set 1872 * JOBCTL_STOP_PENDING on us and we'll re-enter 1873 * TASK_STOPPED in do_signal_stop() on return, so notifying 1874 * the real parent of the group stop completion is enough. 1875 */ 1876 if (gstop_done) 1877 do_notify_parent_cldstop(current, false, why); 1878 1879 /* tasklist protects us from ptrace_freeze_traced() */ 1880 __set_current_state(TASK_RUNNING); 1881 if (clear_code) 1882 current->exit_code = 0; 1883 read_unlock(&tasklist_lock); 1884 } 1885 1886 /* 1887 * We are back. Now reacquire the siglock before touching 1888 * last_siginfo, so that we are sure to have synchronized with 1889 * any signal-sending on another CPU that wants to examine it. 1890 */ 1891 spin_lock_irq(¤t->sighand->siglock); 1892 current->last_siginfo = NULL; 1893 1894 /* LISTENING can be set only during STOP traps, clear it */ 1895 current->jobctl &= ~JOBCTL_LISTENING; 1896 1897 /* 1898 * Queued signals ignored us while we were stopped for tracing. 1899 * So check for any that we should take before resuming user mode. 1900 * This sets TIF_SIGPENDING, but never clears it. 1901 */ 1902 recalc_sigpending_tsk(current); 1903 } 1904 1905 static void ptrace_do_notify(int signr, int exit_code, int why) 1906 { 1907 siginfo_t info; 1908 1909 memset(&info, 0, sizeof info); 1910 info.si_signo = signr; 1911 info.si_code = exit_code; 1912 info.si_pid = task_pid_vnr(current); 1913 info.si_uid = from_kuid_munged(current_user_ns(), current_uid()); 1914 1915 /* Let the debugger run. */ 1916 ptrace_stop(exit_code, why, 1, &info); 1917 } 1918 1919 void ptrace_notify(int exit_code) 1920 { 1921 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP); 1922 if (unlikely(current->task_works)) 1923 task_work_run(); 1924 1925 spin_lock_irq(¤t->sighand->siglock); 1926 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED); 1927 spin_unlock_irq(¤t->sighand->siglock); 1928 } 1929 1930 /** 1931 * do_signal_stop - handle group stop for SIGSTOP and other stop signals 1932 * @signr: signr causing group stop if initiating 1933 * 1934 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr 1935 * and participate in it. If already set, participate in the existing 1936 * group stop. If participated in a group stop (and thus slept), %true is 1937 * returned with siglock released. 1938 * 1939 * If ptraced, this function doesn't handle stop itself. Instead, 1940 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock 1941 * untouched. The caller must ensure that INTERRUPT trap handling takes 1942 * places afterwards. 1943 * 1944 * CONTEXT: 1945 * Must be called with @current->sighand->siglock held, which is released 1946 * on %true return. 1947 * 1948 * RETURNS: 1949 * %false if group stop is already cancelled or ptrace trap is scheduled. 1950 * %true if participated in group stop. 1951 */ 1952 static bool do_signal_stop(int signr) 1953 __releases(¤t->sighand->siglock) 1954 { 1955 struct signal_struct *sig = current->signal; 1956 1957 if (!(current->jobctl & JOBCTL_STOP_PENDING)) { 1958 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME; 1959 struct task_struct *t; 1960 1961 /* signr will be recorded in task->jobctl for retries */ 1962 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK); 1963 1964 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) || 1965 unlikely(signal_group_exit(sig))) 1966 return false; 1967 /* 1968 * There is no group stop already in progress. We must 1969 * initiate one now. 1970 * 1971 * While ptraced, a task may be resumed while group stop is 1972 * still in effect and then receive a stop signal and 1973 * initiate another group stop. This deviates from the 1974 * usual behavior as two consecutive stop signals can't 1975 * cause two group stops when !ptraced. That is why we 1976 * also check !task_is_stopped(t) below. 1977 * 1978 * The condition can be distinguished by testing whether 1979 * SIGNAL_STOP_STOPPED is already set. Don't generate 1980 * group_exit_code in such case. 1981 * 1982 * This is not necessary for SIGNAL_STOP_CONTINUED because 1983 * an intervening stop signal is required to cause two 1984 * continued events regardless of ptrace. 1985 */ 1986 if (!(sig->flags & SIGNAL_STOP_STOPPED)) 1987 sig->group_exit_code = signr; 1988 1989 sig->group_stop_count = 0; 1990 1991 if (task_set_jobctl_pending(current, signr | gstop)) 1992 sig->group_stop_count++; 1993 1994 t = current; 1995 while_each_thread(current, t) { 1996 /* 1997 * Setting state to TASK_STOPPED for a group 1998 * stop is always done with the siglock held, 1999 * so this check has no races. 2000 */ 2001 if (!task_is_stopped(t) && 2002 task_set_jobctl_pending(t, signr | gstop)) { 2003 sig->group_stop_count++; 2004 if (likely(!(t->ptrace & PT_SEIZED))) 2005 signal_wake_up(t, 0); 2006 else 2007 ptrace_trap_notify(t); 2008 } 2009 } 2010 } 2011 2012 if (likely(!current->ptrace)) { 2013 int notify = 0; 2014 2015 /* 2016 * If there are no other threads in the group, or if there 2017 * is a group stop in progress and we are the last to stop, 2018 * report to the parent. 2019 */ 2020 if (task_participate_group_stop(current)) 2021 notify = CLD_STOPPED; 2022 2023 __set_current_state(TASK_STOPPED); 2024 spin_unlock_irq(¤t->sighand->siglock); 2025 2026 /* 2027 * Notify the parent of the group stop completion. Because 2028 * we're not holding either the siglock or tasklist_lock 2029 * here, ptracer may attach inbetween; however, this is for 2030 * group stop and should always be delivered to the real 2031 * parent of the group leader. The new ptracer will get 2032 * its notification when this task transitions into 2033 * TASK_TRACED. 2034 */ 2035 if (notify) { 2036 read_lock(&tasklist_lock); 2037 do_notify_parent_cldstop(current, false, notify); 2038 read_unlock(&tasklist_lock); 2039 } 2040 2041 /* Now we don't run again until woken by SIGCONT or SIGKILL */ 2042 freezable_schedule(); 2043 return true; 2044 } else { 2045 /* 2046 * While ptraced, group stop is handled by STOP trap. 2047 * Schedule it and let the caller deal with it. 2048 */ 2049 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP); 2050 return false; 2051 } 2052 } 2053 2054 /** 2055 * do_jobctl_trap - take care of ptrace jobctl traps 2056 * 2057 * When PT_SEIZED, it's used for both group stop and explicit 2058 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with 2059 * accompanying siginfo. If stopped, lower eight bits of exit_code contain 2060 * the stop signal; otherwise, %SIGTRAP. 2061 * 2062 * When !PT_SEIZED, it's used only for group stop trap with stop signal 2063 * number as exit_code and no siginfo. 2064 * 2065 * CONTEXT: 2066 * Must be called with @current->sighand->siglock held, which may be 2067 * released and re-acquired before returning with intervening sleep. 2068 */ 2069 static void do_jobctl_trap(void) 2070 { 2071 struct signal_struct *signal = current->signal; 2072 int signr = current->jobctl & JOBCTL_STOP_SIGMASK; 2073 2074 if (current->ptrace & PT_SEIZED) { 2075 if (!signal->group_stop_count && 2076 !(signal->flags & SIGNAL_STOP_STOPPED)) 2077 signr = SIGTRAP; 2078 WARN_ON_ONCE(!signr); 2079 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8), 2080 CLD_STOPPED); 2081 } else { 2082 WARN_ON_ONCE(!signr); 2083 ptrace_stop(signr, CLD_STOPPED, 0, NULL); 2084 current->exit_code = 0; 2085 } 2086 } 2087 2088 static int ptrace_signal(int signr, siginfo_t *info) 2089 { 2090 ptrace_signal_deliver(); 2091 /* 2092 * We do not check sig_kernel_stop(signr) but set this marker 2093 * unconditionally because we do not know whether debugger will 2094 * change signr. This flag has no meaning unless we are going 2095 * to stop after return from ptrace_stop(). In this case it will 2096 * be checked in do_signal_stop(), we should only stop if it was 2097 * not cleared by SIGCONT while we were sleeping. See also the 2098 * comment in dequeue_signal(). 2099 */ 2100 current->jobctl |= JOBCTL_STOP_DEQUEUED; 2101 ptrace_stop(signr, CLD_TRAPPED, 0, info); 2102 2103 /* We're back. Did the debugger cancel the sig? */ 2104 signr = current->exit_code; 2105 if (signr == 0) 2106 return signr; 2107 2108 current->exit_code = 0; 2109 2110 /* 2111 * Update the siginfo structure if the signal has 2112 * changed. If the debugger wanted something 2113 * specific in the siginfo structure then it should 2114 * have updated *info via PTRACE_SETSIGINFO. 2115 */ 2116 if (signr != info->si_signo) { 2117 info->si_signo = signr; 2118 info->si_errno = 0; 2119 info->si_code = SI_USER; 2120 rcu_read_lock(); 2121 info->si_pid = task_pid_vnr(current->parent); 2122 info->si_uid = from_kuid_munged(current_user_ns(), 2123 task_uid(current->parent)); 2124 rcu_read_unlock(); 2125 } 2126 2127 /* If the (new) signal is now blocked, requeue it. */ 2128 if (sigismember(¤t->blocked, signr)) { 2129 specific_send_sig_info(signr, info, current); 2130 signr = 0; 2131 } 2132 2133 return signr; 2134 } 2135 2136 int get_signal(struct ksignal *ksig) 2137 { 2138 struct sighand_struct *sighand = current->sighand; 2139 struct signal_struct *signal = current->signal; 2140 int signr; 2141 2142 if (unlikely(current->task_works)) 2143 task_work_run(); 2144 2145 if (unlikely(uprobe_deny_signal())) 2146 return 0; 2147 2148 /* 2149 * Do this once, we can't return to user-mode if freezing() == T. 2150 * do_signal_stop() and ptrace_stop() do freezable_schedule() and 2151 * thus do not need another check after return. 2152 */ 2153 try_to_freeze(); 2154 2155 relock: 2156 spin_lock_irq(&sighand->siglock); 2157 /* 2158 * Every stopped thread goes here after wakeup. Check to see if 2159 * we should notify the parent, prepare_signal(SIGCONT) encodes 2160 * the CLD_ si_code into SIGNAL_CLD_MASK bits. 2161 */ 2162 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) { 2163 int why; 2164 2165 if (signal->flags & SIGNAL_CLD_CONTINUED) 2166 why = CLD_CONTINUED; 2167 else 2168 why = CLD_STOPPED; 2169 2170 signal->flags &= ~SIGNAL_CLD_MASK; 2171 2172 spin_unlock_irq(&sighand->siglock); 2173 2174 /* 2175 * Notify the parent that we're continuing. This event is 2176 * always per-process and doesn't make whole lot of sense 2177 * for ptracers, who shouldn't consume the state via 2178 * wait(2) either, but, for backward compatibility, notify 2179 * the ptracer of the group leader too unless it's gonna be 2180 * a duplicate. 2181 */ 2182 read_lock(&tasklist_lock); 2183 do_notify_parent_cldstop(current, false, why); 2184 2185 if (ptrace_reparented(current->group_leader)) 2186 do_notify_parent_cldstop(current->group_leader, 2187 true, why); 2188 read_unlock(&tasklist_lock); 2189 2190 goto relock; 2191 } 2192 2193 for (;;) { 2194 struct k_sigaction *ka; 2195 2196 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) && 2197 do_signal_stop(0)) 2198 goto relock; 2199 2200 if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) { 2201 do_jobctl_trap(); 2202 spin_unlock_irq(&sighand->siglock); 2203 goto relock; 2204 } 2205 2206 signr = dequeue_signal(current, ¤t->blocked, &ksig->info); 2207 2208 if (!signr) 2209 break; /* will return 0 */ 2210 2211 if (unlikely(current->ptrace) && signr != SIGKILL) { 2212 signr = ptrace_signal(signr, &ksig->info); 2213 if (!signr) 2214 continue; 2215 } 2216 2217 ka = &sighand->action[signr-1]; 2218 2219 /* Trace actually delivered signals. */ 2220 trace_signal_deliver(signr, &ksig->info, ka); 2221 2222 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */ 2223 continue; 2224 if (ka->sa.sa_handler != SIG_DFL) { 2225 /* Run the handler. */ 2226 ksig->ka = *ka; 2227 2228 if (ka->sa.sa_flags & SA_ONESHOT) 2229 ka->sa.sa_handler = SIG_DFL; 2230 2231 break; /* will return non-zero "signr" value */ 2232 } 2233 2234 /* 2235 * Now we are doing the default action for this signal. 2236 */ 2237 if (sig_kernel_ignore(signr)) /* Default is nothing. */ 2238 continue; 2239 2240 /* 2241 * Global init gets no signals it doesn't want. 2242 * Container-init gets no signals it doesn't want from same 2243 * container. 2244 * 2245 * Note that if global/container-init sees a sig_kernel_only() 2246 * signal here, the signal must have been generated internally 2247 * or must have come from an ancestor namespace. In either 2248 * case, the signal cannot be dropped. 2249 */ 2250 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) && 2251 !sig_kernel_only(signr)) 2252 continue; 2253 2254 if (sig_kernel_stop(signr)) { 2255 /* 2256 * The default action is to stop all threads in 2257 * the thread group. The job control signals 2258 * do nothing in an orphaned pgrp, but SIGSTOP 2259 * always works. Note that siglock needs to be 2260 * dropped during the call to is_orphaned_pgrp() 2261 * because of lock ordering with tasklist_lock. 2262 * This allows an intervening SIGCONT to be posted. 2263 * We need to check for that and bail out if necessary. 2264 */ 2265 if (signr != SIGSTOP) { 2266 spin_unlock_irq(&sighand->siglock); 2267 2268 /* signals can be posted during this window */ 2269 2270 if (is_current_pgrp_orphaned()) 2271 goto relock; 2272 2273 spin_lock_irq(&sighand->siglock); 2274 } 2275 2276 if (likely(do_signal_stop(ksig->info.si_signo))) { 2277 /* It released the siglock. */ 2278 goto relock; 2279 } 2280 2281 /* 2282 * We didn't actually stop, due to a race 2283 * with SIGCONT or something like that. 2284 */ 2285 continue; 2286 } 2287 2288 spin_unlock_irq(&sighand->siglock); 2289 2290 /* 2291 * Anything else is fatal, maybe with a core dump. 2292 */ 2293 current->flags |= PF_SIGNALED; 2294 2295 if (sig_kernel_coredump(signr)) { 2296 if (print_fatal_signals) 2297 print_fatal_signal(ksig->info.si_signo); 2298 proc_coredump_connector(current); 2299 /* 2300 * If it was able to dump core, this kills all 2301 * other threads in the group and synchronizes with 2302 * their demise. If we lost the race with another 2303 * thread getting here, it set group_exit_code 2304 * first and our do_group_exit call below will use 2305 * that value and ignore the one we pass it. 2306 */ 2307 do_coredump(&ksig->info); 2308 } 2309 2310 /* 2311 * Death signals, no core dump. 2312 */ 2313 do_group_exit(ksig->info.si_signo); 2314 /* NOTREACHED */ 2315 } 2316 spin_unlock_irq(&sighand->siglock); 2317 2318 ksig->sig = signr; 2319 return ksig->sig > 0; 2320 } 2321 2322 /** 2323 * signal_delivered - 2324 * @ksig: kernel signal struct 2325 * @stepping: nonzero if debugger single-step or block-step in use 2326 * 2327 * This function should be called when a signal has successfully been 2328 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask 2329 * is always blocked, and the signal itself is blocked unless %SA_NODEFER 2330 * is set in @ksig->ka.sa.sa_flags. Tracing is notified. 2331 */ 2332 static void signal_delivered(struct ksignal *ksig, int stepping) 2333 { 2334 sigset_t blocked; 2335 2336 /* A signal was successfully delivered, and the 2337 saved sigmask was stored on the signal frame, 2338 and will be restored by sigreturn. So we can 2339 simply clear the restore sigmask flag. */ 2340 clear_restore_sigmask(); 2341 2342 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask); 2343 if (!(ksig->ka.sa.sa_flags & SA_NODEFER)) 2344 sigaddset(&blocked, ksig->sig); 2345 set_current_blocked(&blocked); 2346 tracehook_signal_handler(stepping); 2347 } 2348 2349 void signal_setup_done(int failed, struct ksignal *ksig, int stepping) 2350 { 2351 if (failed) 2352 force_sigsegv(ksig->sig, current); 2353 else 2354 signal_delivered(ksig, stepping); 2355 } 2356 2357 /* 2358 * It could be that complete_signal() picked us to notify about the 2359 * group-wide signal. Other threads should be notified now to take 2360 * the shared signals in @which since we will not. 2361 */ 2362 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which) 2363 { 2364 sigset_t retarget; 2365 struct task_struct *t; 2366 2367 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which); 2368 if (sigisemptyset(&retarget)) 2369 return; 2370 2371 t = tsk; 2372 while_each_thread(tsk, t) { 2373 if (t->flags & PF_EXITING) 2374 continue; 2375 2376 if (!has_pending_signals(&retarget, &t->blocked)) 2377 continue; 2378 /* Remove the signals this thread can handle. */ 2379 sigandsets(&retarget, &retarget, &t->blocked); 2380 2381 if (!signal_pending(t)) 2382 signal_wake_up(t, 0); 2383 2384 if (sigisemptyset(&retarget)) 2385 break; 2386 } 2387 } 2388 2389 void exit_signals(struct task_struct *tsk) 2390 { 2391 int group_stop = 0; 2392 sigset_t unblocked; 2393 2394 /* 2395 * @tsk is about to have PF_EXITING set - lock out users which 2396 * expect stable threadgroup. 2397 */ 2398 threadgroup_change_begin(tsk); 2399 2400 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) { 2401 tsk->flags |= PF_EXITING; 2402 threadgroup_change_end(tsk); 2403 return; 2404 } 2405 2406 spin_lock_irq(&tsk->sighand->siglock); 2407 /* 2408 * From now this task is not visible for group-wide signals, 2409 * see wants_signal(), do_signal_stop(). 2410 */ 2411 tsk->flags |= PF_EXITING; 2412 2413 threadgroup_change_end(tsk); 2414 2415 if (!signal_pending(tsk)) 2416 goto out; 2417 2418 unblocked = tsk->blocked; 2419 signotset(&unblocked); 2420 retarget_shared_pending(tsk, &unblocked); 2421 2422 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) && 2423 task_participate_group_stop(tsk)) 2424 group_stop = CLD_STOPPED; 2425 out: 2426 spin_unlock_irq(&tsk->sighand->siglock); 2427 2428 /* 2429 * If group stop has completed, deliver the notification. This 2430 * should always go to the real parent of the group leader. 2431 */ 2432 if (unlikely(group_stop)) { 2433 read_lock(&tasklist_lock); 2434 do_notify_parent_cldstop(tsk, false, group_stop); 2435 read_unlock(&tasklist_lock); 2436 } 2437 } 2438 2439 EXPORT_SYMBOL(recalc_sigpending); 2440 EXPORT_SYMBOL_GPL(dequeue_signal); 2441 EXPORT_SYMBOL(flush_signals); 2442 EXPORT_SYMBOL(force_sig); 2443 EXPORT_SYMBOL(send_sig); 2444 EXPORT_SYMBOL(send_sig_info); 2445 EXPORT_SYMBOL(sigprocmask); 2446 2447 /* 2448 * System call entry points. 2449 */ 2450 2451 /** 2452 * sys_restart_syscall - restart a system call 2453 */ 2454 SYSCALL_DEFINE0(restart_syscall) 2455 { 2456 struct restart_block *restart = ¤t->restart_block; 2457 return restart->fn(restart); 2458 } 2459 2460 long do_no_restart_syscall(struct restart_block *param) 2461 { 2462 return -EINTR; 2463 } 2464 2465 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset) 2466 { 2467 if (signal_pending(tsk) && !thread_group_empty(tsk)) { 2468 sigset_t newblocked; 2469 /* A set of now blocked but previously unblocked signals. */ 2470 sigandnsets(&newblocked, newset, ¤t->blocked); 2471 retarget_shared_pending(tsk, &newblocked); 2472 } 2473 tsk->blocked = *newset; 2474 recalc_sigpending(); 2475 } 2476 2477 /** 2478 * set_current_blocked - change current->blocked mask 2479 * @newset: new mask 2480 * 2481 * It is wrong to change ->blocked directly, this helper should be used 2482 * to ensure the process can't miss a shared signal we are going to block. 2483 */ 2484 void set_current_blocked(sigset_t *newset) 2485 { 2486 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP)); 2487 __set_current_blocked(newset); 2488 } 2489 2490 void __set_current_blocked(const sigset_t *newset) 2491 { 2492 struct task_struct *tsk = current; 2493 2494 /* 2495 * In case the signal mask hasn't changed, there is nothing we need 2496 * to do. The current->blocked shouldn't be modified by other task. 2497 */ 2498 if (sigequalsets(&tsk->blocked, newset)) 2499 return; 2500 2501 spin_lock_irq(&tsk->sighand->siglock); 2502 __set_task_blocked(tsk, newset); 2503 spin_unlock_irq(&tsk->sighand->siglock); 2504 } 2505 2506 /* 2507 * This is also useful for kernel threads that want to temporarily 2508 * (or permanently) block certain signals. 2509 * 2510 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel 2511 * interface happily blocks "unblockable" signals like SIGKILL 2512 * and friends. 2513 */ 2514 int sigprocmask(int how, sigset_t *set, sigset_t *oldset) 2515 { 2516 struct task_struct *tsk = current; 2517 sigset_t newset; 2518 2519 /* Lockless, only current can change ->blocked, never from irq */ 2520 if (oldset) 2521 *oldset = tsk->blocked; 2522 2523 switch (how) { 2524 case SIG_BLOCK: 2525 sigorsets(&newset, &tsk->blocked, set); 2526 break; 2527 case SIG_UNBLOCK: 2528 sigandnsets(&newset, &tsk->blocked, set); 2529 break; 2530 case SIG_SETMASK: 2531 newset = *set; 2532 break; 2533 default: 2534 return -EINVAL; 2535 } 2536 2537 __set_current_blocked(&newset); 2538 return 0; 2539 } 2540 2541 /** 2542 * sys_rt_sigprocmask - change the list of currently blocked signals 2543 * @how: whether to add, remove, or set signals 2544 * @nset: stores pending signals 2545 * @oset: previous value of signal mask if non-null 2546 * @sigsetsize: size of sigset_t type 2547 */ 2548 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset, 2549 sigset_t __user *, oset, size_t, sigsetsize) 2550 { 2551 sigset_t old_set, new_set; 2552 int error; 2553 2554 /* XXX: Don't preclude handling different sized sigset_t's. */ 2555 if (sigsetsize != sizeof(sigset_t)) 2556 return -EINVAL; 2557 2558 old_set = current->blocked; 2559 2560 if (nset) { 2561 if (copy_from_user(&new_set, nset, sizeof(sigset_t))) 2562 return -EFAULT; 2563 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); 2564 2565 error = sigprocmask(how, &new_set, NULL); 2566 if (error) 2567 return error; 2568 } 2569 2570 if (oset) { 2571 if (copy_to_user(oset, &old_set, sizeof(sigset_t))) 2572 return -EFAULT; 2573 } 2574 2575 return 0; 2576 } 2577 2578 #ifdef CONFIG_COMPAT 2579 COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset, 2580 compat_sigset_t __user *, oset, compat_size_t, sigsetsize) 2581 { 2582 #ifdef __BIG_ENDIAN 2583 sigset_t old_set = current->blocked; 2584 2585 /* XXX: Don't preclude handling different sized sigset_t's. */ 2586 if (sigsetsize != sizeof(sigset_t)) 2587 return -EINVAL; 2588 2589 if (nset) { 2590 compat_sigset_t new32; 2591 sigset_t new_set; 2592 int error; 2593 if (copy_from_user(&new32, nset, sizeof(compat_sigset_t))) 2594 return -EFAULT; 2595 2596 sigset_from_compat(&new_set, &new32); 2597 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); 2598 2599 error = sigprocmask(how, &new_set, NULL); 2600 if (error) 2601 return error; 2602 } 2603 if (oset) { 2604 compat_sigset_t old32; 2605 sigset_to_compat(&old32, &old_set); 2606 if (copy_to_user(oset, &old32, sizeof(compat_sigset_t))) 2607 return -EFAULT; 2608 } 2609 return 0; 2610 #else 2611 return sys_rt_sigprocmask(how, (sigset_t __user *)nset, 2612 (sigset_t __user *)oset, sigsetsize); 2613 #endif 2614 } 2615 #endif 2616 2617 static int do_sigpending(void *set, unsigned long sigsetsize) 2618 { 2619 if (sigsetsize > sizeof(sigset_t)) 2620 return -EINVAL; 2621 2622 spin_lock_irq(¤t->sighand->siglock); 2623 sigorsets(set, ¤t->pending.signal, 2624 ¤t->signal->shared_pending.signal); 2625 spin_unlock_irq(¤t->sighand->siglock); 2626 2627 /* Outside the lock because only this thread touches it. */ 2628 sigandsets(set, ¤t->blocked, set); 2629 return 0; 2630 } 2631 2632 /** 2633 * sys_rt_sigpending - examine a pending signal that has been raised 2634 * while blocked 2635 * @uset: stores pending signals 2636 * @sigsetsize: size of sigset_t type or larger 2637 */ 2638 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize) 2639 { 2640 sigset_t set; 2641 int err = do_sigpending(&set, sigsetsize); 2642 if (!err && copy_to_user(uset, &set, sigsetsize)) 2643 err = -EFAULT; 2644 return err; 2645 } 2646 2647 #ifdef CONFIG_COMPAT 2648 COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset, 2649 compat_size_t, sigsetsize) 2650 { 2651 #ifdef __BIG_ENDIAN 2652 sigset_t set; 2653 int err = do_sigpending(&set, sigsetsize); 2654 if (!err) { 2655 compat_sigset_t set32; 2656 sigset_to_compat(&set32, &set); 2657 /* we can get here only if sigsetsize <= sizeof(set) */ 2658 if (copy_to_user(uset, &set32, sigsetsize)) 2659 err = -EFAULT; 2660 } 2661 return err; 2662 #else 2663 return sys_rt_sigpending((sigset_t __user *)uset, sigsetsize); 2664 #endif 2665 } 2666 #endif 2667 2668 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER 2669 2670 int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from) 2671 { 2672 int err; 2673 2674 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t))) 2675 return -EFAULT; 2676 if (from->si_code < 0) 2677 return __copy_to_user(to, from, sizeof(siginfo_t)) 2678 ? -EFAULT : 0; 2679 /* 2680 * If you change siginfo_t structure, please be sure 2681 * this code is fixed accordingly. 2682 * Please remember to update the signalfd_copyinfo() function 2683 * inside fs/signalfd.c too, in case siginfo_t changes. 2684 * It should never copy any pad contained in the structure 2685 * to avoid security leaks, but must copy the generic 2686 * 3 ints plus the relevant union member. 2687 */ 2688 err = __put_user(from->si_signo, &to->si_signo); 2689 err |= __put_user(from->si_errno, &to->si_errno); 2690 err |= __put_user((short)from->si_code, &to->si_code); 2691 switch (from->si_code & __SI_MASK) { 2692 case __SI_KILL: 2693 err |= __put_user(from->si_pid, &to->si_pid); 2694 err |= __put_user(from->si_uid, &to->si_uid); 2695 break; 2696 case __SI_TIMER: 2697 err |= __put_user(from->si_tid, &to->si_tid); 2698 err |= __put_user(from->si_overrun, &to->si_overrun); 2699 err |= __put_user(from->si_ptr, &to->si_ptr); 2700 break; 2701 case __SI_POLL: 2702 err |= __put_user(from->si_band, &to->si_band); 2703 err |= __put_user(from->si_fd, &to->si_fd); 2704 break; 2705 case __SI_FAULT: 2706 err |= __put_user(from->si_addr, &to->si_addr); 2707 #ifdef __ARCH_SI_TRAPNO 2708 err |= __put_user(from->si_trapno, &to->si_trapno); 2709 #endif 2710 #ifdef BUS_MCEERR_AO 2711 /* 2712 * Other callers might not initialize the si_lsb field, 2713 * so check explicitly for the right codes here. 2714 */ 2715 if (from->si_signo == SIGBUS && 2716 (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)) 2717 err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb); 2718 #endif 2719 #ifdef SEGV_BNDERR 2720 if (from->si_signo == SIGSEGV && from->si_code == SEGV_BNDERR) { 2721 err |= __put_user(from->si_lower, &to->si_lower); 2722 err |= __put_user(from->si_upper, &to->si_upper); 2723 } 2724 #endif 2725 #ifdef SEGV_PKUERR 2726 if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR) 2727 err |= __put_user(from->si_pkey, &to->si_pkey); 2728 #endif 2729 break; 2730 case __SI_CHLD: 2731 err |= __put_user(from->si_pid, &to->si_pid); 2732 err |= __put_user(from->si_uid, &to->si_uid); 2733 err |= __put_user(from->si_status, &to->si_status); 2734 err |= __put_user(from->si_utime, &to->si_utime); 2735 err |= __put_user(from->si_stime, &to->si_stime); 2736 break; 2737 case __SI_RT: /* This is not generated by the kernel as of now. */ 2738 case __SI_MESGQ: /* But this is */ 2739 err |= __put_user(from->si_pid, &to->si_pid); 2740 err |= __put_user(from->si_uid, &to->si_uid); 2741 err |= __put_user(from->si_ptr, &to->si_ptr); 2742 break; 2743 #ifdef __ARCH_SIGSYS 2744 case __SI_SYS: 2745 err |= __put_user(from->si_call_addr, &to->si_call_addr); 2746 err |= __put_user(from->si_syscall, &to->si_syscall); 2747 err |= __put_user(from->si_arch, &to->si_arch); 2748 break; 2749 #endif 2750 default: /* this is just in case for now ... */ 2751 err |= __put_user(from->si_pid, &to->si_pid); 2752 err |= __put_user(from->si_uid, &to->si_uid); 2753 break; 2754 } 2755 return err; 2756 } 2757 2758 #endif 2759 2760 /** 2761 * do_sigtimedwait - wait for queued signals specified in @which 2762 * @which: queued signals to wait for 2763 * @info: if non-null, the signal's siginfo is returned here 2764 * @ts: upper bound on process time suspension 2765 */ 2766 int do_sigtimedwait(const sigset_t *which, siginfo_t *info, 2767 const struct timespec *ts) 2768 { 2769 ktime_t *to = NULL, timeout = KTIME_MAX; 2770 struct task_struct *tsk = current; 2771 sigset_t mask = *which; 2772 int sig, ret = 0; 2773 2774 if (ts) { 2775 if (!timespec_valid(ts)) 2776 return -EINVAL; 2777 timeout = timespec_to_ktime(*ts); 2778 to = &timeout; 2779 } 2780 2781 /* 2782 * Invert the set of allowed signals to get those we want to block. 2783 */ 2784 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP)); 2785 signotset(&mask); 2786 2787 spin_lock_irq(&tsk->sighand->siglock); 2788 sig = dequeue_signal(tsk, &mask, info); 2789 if (!sig && timeout) { 2790 /* 2791 * None ready, temporarily unblock those we're interested 2792 * while we are sleeping in so that we'll be awakened when 2793 * they arrive. Unblocking is always fine, we can avoid 2794 * set_current_blocked(). 2795 */ 2796 tsk->real_blocked = tsk->blocked; 2797 sigandsets(&tsk->blocked, &tsk->blocked, &mask); 2798 recalc_sigpending(); 2799 spin_unlock_irq(&tsk->sighand->siglock); 2800 2801 __set_current_state(TASK_INTERRUPTIBLE); 2802 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns, 2803 HRTIMER_MODE_REL); 2804 spin_lock_irq(&tsk->sighand->siglock); 2805 __set_task_blocked(tsk, &tsk->real_blocked); 2806 sigemptyset(&tsk->real_blocked); 2807 sig = dequeue_signal(tsk, &mask, info); 2808 } 2809 spin_unlock_irq(&tsk->sighand->siglock); 2810 2811 if (sig) 2812 return sig; 2813 return ret ? -EINTR : -EAGAIN; 2814 } 2815 2816 /** 2817 * sys_rt_sigtimedwait - synchronously wait for queued signals specified 2818 * in @uthese 2819 * @uthese: queued signals to wait for 2820 * @uinfo: if non-null, the signal's siginfo is returned here 2821 * @uts: upper bound on process time suspension 2822 * @sigsetsize: size of sigset_t type 2823 */ 2824 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese, 2825 siginfo_t __user *, uinfo, const struct timespec __user *, uts, 2826 size_t, sigsetsize) 2827 { 2828 sigset_t these; 2829 struct timespec ts; 2830 siginfo_t info; 2831 int ret; 2832 2833 /* XXX: Don't preclude handling different sized sigset_t's. */ 2834 if (sigsetsize != sizeof(sigset_t)) 2835 return -EINVAL; 2836 2837 if (copy_from_user(&these, uthese, sizeof(these))) 2838 return -EFAULT; 2839 2840 if (uts) { 2841 if (copy_from_user(&ts, uts, sizeof(ts))) 2842 return -EFAULT; 2843 } 2844 2845 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL); 2846 2847 if (ret > 0 && uinfo) { 2848 if (copy_siginfo_to_user(uinfo, &info)) 2849 ret = -EFAULT; 2850 } 2851 2852 return ret; 2853 } 2854 2855 /** 2856 * sys_kill - send a signal to a process 2857 * @pid: the PID of the process 2858 * @sig: signal to be sent 2859 */ 2860 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig) 2861 { 2862 struct siginfo info; 2863 2864 info.si_signo = sig; 2865 info.si_errno = 0; 2866 info.si_code = SI_USER; 2867 info.si_pid = task_tgid_vnr(current); 2868 info.si_uid = from_kuid_munged(current_user_ns(), current_uid()); 2869 2870 return kill_something_info(sig, &info, pid); 2871 } 2872 2873 static int 2874 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info) 2875 { 2876 struct task_struct *p; 2877 int error = -ESRCH; 2878 2879 rcu_read_lock(); 2880 p = find_task_by_vpid(pid); 2881 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) { 2882 error = check_kill_permission(sig, info, p); 2883 /* 2884 * The null signal is a permissions and process existence 2885 * probe. No signal is actually delivered. 2886 */ 2887 if (!error && sig) { 2888 error = do_send_sig_info(sig, info, p, false); 2889 /* 2890 * If lock_task_sighand() failed we pretend the task 2891 * dies after receiving the signal. The window is tiny, 2892 * and the signal is private anyway. 2893 */ 2894 if (unlikely(error == -ESRCH)) 2895 error = 0; 2896 } 2897 } 2898 rcu_read_unlock(); 2899 2900 return error; 2901 } 2902 2903 static int do_tkill(pid_t tgid, pid_t pid, int sig) 2904 { 2905 struct siginfo info = {}; 2906 2907 info.si_signo = sig; 2908 info.si_errno = 0; 2909 info.si_code = SI_TKILL; 2910 info.si_pid = task_tgid_vnr(current); 2911 info.si_uid = from_kuid_munged(current_user_ns(), current_uid()); 2912 2913 return do_send_specific(tgid, pid, sig, &info); 2914 } 2915 2916 /** 2917 * sys_tgkill - send signal to one specific thread 2918 * @tgid: the thread group ID of the thread 2919 * @pid: the PID of the thread 2920 * @sig: signal to be sent 2921 * 2922 * This syscall also checks the @tgid and returns -ESRCH even if the PID 2923 * exists but it's not belonging to the target process anymore. This 2924 * method solves the problem of threads exiting and PIDs getting reused. 2925 */ 2926 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig) 2927 { 2928 /* This is only valid for single tasks */ 2929 if (pid <= 0 || tgid <= 0) 2930 return -EINVAL; 2931 2932 return do_tkill(tgid, pid, sig); 2933 } 2934 2935 /** 2936 * sys_tkill - send signal to one specific task 2937 * @pid: the PID of the task 2938 * @sig: signal to be sent 2939 * 2940 * Send a signal to only one task, even if it's a CLONE_THREAD task. 2941 */ 2942 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig) 2943 { 2944 /* This is only valid for single tasks */ 2945 if (pid <= 0) 2946 return -EINVAL; 2947 2948 return do_tkill(0, pid, sig); 2949 } 2950 2951 static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info) 2952 { 2953 /* Not even root can pretend to send signals from the kernel. 2954 * Nor can they impersonate a kill()/tgkill(), which adds source info. 2955 */ 2956 if ((info->si_code >= 0 || info->si_code == SI_TKILL) && 2957 (task_pid_vnr(current) != pid)) 2958 return -EPERM; 2959 2960 info->si_signo = sig; 2961 2962 /* POSIX.1b doesn't mention process groups. */ 2963 return kill_proc_info(sig, info, pid); 2964 } 2965 2966 /** 2967 * sys_rt_sigqueueinfo - send signal information to a signal 2968 * @pid: the PID of the thread 2969 * @sig: signal to be sent 2970 * @uinfo: signal info to be sent 2971 */ 2972 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig, 2973 siginfo_t __user *, uinfo) 2974 { 2975 siginfo_t info; 2976 if (copy_from_user(&info, uinfo, sizeof(siginfo_t))) 2977 return -EFAULT; 2978 return do_rt_sigqueueinfo(pid, sig, &info); 2979 } 2980 2981 #ifdef CONFIG_COMPAT 2982 COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo, 2983 compat_pid_t, pid, 2984 int, sig, 2985 struct compat_siginfo __user *, uinfo) 2986 { 2987 siginfo_t info = {}; 2988 int ret = copy_siginfo_from_user32(&info, uinfo); 2989 if (unlikely(ret)) 2990 return ret; 2991 return do_rt_sigqueueinfo(pid, sig, &info); 2992 } 2993 #endif 2994 2995 static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info) 2996 { 2997 /* This is only valid for single tasks */ 2998 if (pid <= 0 || tgid <= 0) 2999 return -EINVAL; 3000 3001 /* Not even root can pretend to send signals from the kernel. 3002 * Nor can they impersonate a kill()/tgkill(), which adds source info. 3003 */ 3004 if ((info->si_code >= 0 || info->si_code == SI_TKILL) && 3005 (task_pid_vnr(current) != pid)) 3006 return -EPERM; 3007 3008 info->si_signo = sig; 3009 3010 return do_send_specific(tgid, pid, sig, info); 3011 } 3012 3013 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig, 3014 siginfo_t __user *, uinfo) 3015 { 3016 siginfo_t info; 3017 3018 if (copy_from_user(&info, uinfo, sizeof(siginfo_t))) 3019 return -EFAULT; 3020 3021 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info); 3022 } 3023 3024 #ifdef CONFIG_COMPAT 3025 COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo, 3026 compat_pid_t, tgid, 3027 compat_pid_t, pid, 3028 int, sig, 3029 struct compat_siginfo __user *, uinfo) 3030 { 3031 siginfo_t info = {}; 3032 3033 if (copy_siginfo_from_user32(&info, uinfo)) 3034 return -EFAULT; 3035 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info); 3036 } 3037 #endif 3038 3039 /* 3040 * For kthreads only, must not be used if cloned with CLONE_SIGHAND 3041 */ 3042 void kernel_sigaction(int sig, __sighandler_t action) 3043 { 3044 spin_lock_irq(¤t->sighand->siglock); 3045 current->sighand->action[sig - 1].sa.sa_handler = action; 3046 if (action == SIG_IGN) { 3047 sigset_t mask; 3048 3049 sigemptyset(&mask); 3050 sigaddset(&mask, sig); 3051 3052 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending); 3053 flush_sigqueue_mask(&mask, ¤t->pending); 3054 recalc_sigpending(); 3055 } 3056 spin_unlock_irq(¤t->sighand->siglock); 3057 } 3058 EXPORT_SYMBOL(kernel_sigaction); 3059 3060 void __weak sigaction_compat_abi(struct k_sigaction *act, 3061 struct k_sigaction *oact) 3062 { 3063 } 3064 3065 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) 3066 { 3067 struct task_struct *p = current, *t; 3068 struct k_sigaction *k; 3069 sigset_t mask; 3070 3071 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig))) 3072 return -EINVAL; 3073 3074 k = &p->sighand->action[sig-1]; 3075 3076 spin_lock_irq(&p->sighand->siglock); 3077 if (oact) 3078 *oact = *k; 3079 3080 sigaction_compat_abi(act, oact); 3081 3082 if (act) { 3083 sigdelsetmask(&act->sa.sa_mask, 3084 sigmask(SIGKILL) | sigmask(SIGSTOP)); 3085 *k = *act; 3086 /* 3087 * POSIX 3.3.1.3: 3088 * "Setting a signal action to SIG_IGN for a signal that is 3089 * pending shall cause the pending signal to be discarded, 3090 * whether or not it is blocked." 3091 * 3092 * "Setting a signal action to SIG_DFL for a signal that is 3093 * pending and whose default action is to ignore the signal 3094 * (for example, SIGCHLD), shall cause the pending signal to 3095 * be discarded, whether or not it is blocked" 3096 */ 3097 if (sig_handler_ignored(sig_handler(p, sig), sig)) { 3098 sigemptyset(&mask); 3099 sigaddset(&mask, sig); 3100 flush_sigqueue_mask(&mask, &p->signal->shared_pending); 3101 for_each_thread(p, t) 3102 flush_sigqueue_mask(&mask, &t->pending); 3103 } 3104 } 3105 3106 spin_unlock_irq(&p->sighand->siglock); 3107 return 0; 3108 } 3109 3110 static int 3111 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp) 3112 { 3113 stack_t oss; 3114 int error; 3115 3116 oss.ss_sp = (void __user *) current->sas_ss_sp; 3117 oss.ss_size = current->sas_ss_size; 3118 oss.ss_flags = sas_ss_flags(sp) | 3119 (current->sas_ss_flags & SS_FLAG_BITS); 3120 3121 if (uss) { 3122 void __user *ss_sp; 3123 size_t ss_size; 3124 unsigned ss_flags; 3125 int ss_mode; 3126 3127 error = -EFAULT; 3128 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))) 3129 goto out; 3130 error = __get_user(ss_sp, &uss->ss_sp) | 3131 __get_user(ss_flags, &uss->ss_flags) | 3132 __get_user(ss_size, &uss->ss_size); 3133 if (error) 3134 goto out; 3135 3136 error = -EPERM; 3137 if (on_sig_stack(sp)) 3138 goto out; 3139 3140 ss_mode = ss_flags & ~SS_FLAG_BITS; 3141 error = -EINVAL; 3142 if (ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK && 3143 ss_mode != 0) 3144 goto out; 3145 3146 if (ss_mode == SS_DISABLE) { 3147 ss_size = 0; 3148 ss_sp = NULL; 3149 } else { 3150 error = -ENOMEM; 3151 if (ss_size < MINSIGSTKSZ) 3152 goto out; 3153 } 3154 3155 current->sas_ss_sp = (unsigned long) ss_sp; 3156 current->sas_ss_size = ss_size; 3157 current->sas_ss_flags = ss_flags; 3158 } 3159 3160 error = 0; 3161 if (uoss) { 3162 error = -EFAULT; 3163 if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss))) 3164 goto out; 3165 error = __put_user(oss.ss_sp, &uoss->ss_sp) | 3166 __put_user(oss.ss_size, &uoss->ss_size) | 3167 __put_user(oss.ss_flags, &uoss->ss_flags); 3168 } 3169 3170 out: 3171 return error; 3172 } 3173 SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss) 3174 { 3175 return do_sigaltstack(uss, uoss, current_user_stack_pointer()); 3176 } 3177 3178 int restore_altstack(const stack_t __user *uss) 3179 { 3180 int err = do_sigaltstack(uss, NULL, current_user_stack_pointer()); 3181 /* squash all but EFAULT for now */ 3182 return err == -EFAULT ? err : 0; 3183 } 3184 3185 int __save_altstack(stack_t __user *uss, unsigned long sp) 3186 { 3187 struct task_struct *t = current; 3188 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) | 3189 __put_user(t->sas_ss_flags, &uss->ss_flags) | 3190 __put_user(t->sas_ss_size, &uss->ss_size); 3191 if (err) 3192 return err; 3193 if (t->sas_ss_flags & SS_AUTODISARM) 3194 sas_ss_reset(t); 3195 return 0; 3196 } 3197 3198 #ifdef CONFIG_COMPAT 3199 COMPAT_SYSCALL_DEFINE2(sigaltstack, 3200 const compat_stack_t __user *, uss_ptr, 3201 compat_stack_t __user *, uoss_ptr) 3202 { 3203 stack_t uss, uoss; 3204 int ret; 3205 mm_segment_t seg; 3206 3207 if (uss_ptr) { 3208 compat_stack_t uss32; 3209 3210 memset(&uss, 0, sizeof(stack_t)); 3211 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t))) 3212 return -EFAULT; 3213 uss.ss_sp = compat_ptr(uss32.ss_sp); 3214 uss.ss_flags = uss32.ss_flags; 3215 uss.ss_size = uss32.ss_size; 3216 } 3217 seg = get_fs(); 3218 set_fs(KERNEL_DS); 3219 ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL), 3220 (stack_t __force __user *) &uoss, 3221 compat_user_stack_pointer()); 3222 set_fs(seg); 3223 if (ret >= 0 && uoss_ptr) { 3224 if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) || 3225 __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) || 3226 __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) || 3227 __put_user(uoss.ss_size, &uoss_ptr->ss_size)) 3228 ret = -EFAULT; 3229 } 3230 return ret; 3231 } 3232 3233 int compat_restore_altstack(const compat_stack_t __user *uss) 3234 { 3235 int err = compat_sys_sigaltstack(uss, NULL); 3236 /* squash all but -EFAULT for now */ 3237 return err == -EFAULT ? err : 0; 3238 } 3239 3240 int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp) 3241 { 3242 struct task_struct *t = current; 3243 return __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), &uss->ss_sp) | 3244 __put_user(sas_ss_flags(sp), &uss->ss_flags) | 3245 __put_user(t->sas_ss_size, &uss->ss_size); 3246 } 3247 #endif 3248 3249 #ifdef __ARCH_WANT_SYS_SIGPENDING 3250 3251 /** 3252 * sys_sigpending - examine pending signals 3253 * @set: where mask of pending signal is returned 3254 */ 3255 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set) 3256 { 3257 return sys_rt_sigpending((sigset_t __user *)set, sizeof(old_sigset_t)); 3258 } 3259 3260 #endif 3261 3262 #ifdef __ARCH_WANT_SYS_SIGPROCMASK 3263 /** 3264 * sys_sigprocmask - examine and change blocked signals 3265 * @how: whether to add, remove, or set signals 3266 * @nset: signals to add or remove (if non-null) 3267 * @oset: previous value of signal mask if non-null 3268 * 3269 * Some platforms have their own version with special arguments; 3270 * others support only sys_rt_sigprocmask. 3271 */ 3272 3273 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset, 3274 old_sigset_t __user *, oset) 3275 { 3276 old_sigset_t old_set, new_set; 3277 sigset_t new_blocked; 3278 3279 old_set = current->blocked.sig[0]; 3280 3281 if (nset) { 3282 if (copy_from_user(&new_set, nset, sizeof(*nset))) 3283 return -EFAULT; 3284 3285 new_blocked = current->blocked; 3286 3287 switch (how) { 3288 case SIG_BLOCK: 3289 sigaddsetmask(&new_blocked, new_set); 3290 break; 3291 case SIG_UNBLOCK: 3292 sigdelsetmask(&new_blocked, new_set); 3293 break; 3294 case SIG_SETMASK: 3295 new_blocked.sig[0] = new_set; 3296 break; 3297 default: 3298 return -EINVAL; 3299 } 3300 3301 set_current_blocked(&new_blocked); 3302 } 3303 3304 if (oset) { 3305 if (copy_to_user(oset, &old_set, sizeof(*oset))) 3306 return -EFAULT; 3307 } 3308 3309 return 0; 3310 } 3311 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */ 3312 3313 #ifndef CONFIG_ODD_RT_SIGACTION 3314 /** 3315 * sys_rt_sigaction - alter an action taken by a process 3316 * @sig: signal to be sent 3317 * @act: new sigaction 3318 * @oact: used to save the previous sigaction 3319 * @sigsetsize: size of sigset_t type 3320 */ 3321 SYSCALL_DEFINE4(rt_sigaction, int, sig, 3322 const struct sigaction __user *, act, 3323 struct sigaction __user *, oact, 3324 size_t, sigsetsize) 3325 { 3326 struct k_sigaction new_sa, old_sa; 3327 int ret = -EINVAL; 3328 3329 /* XXX: Don't preclude handling different sized sigset_t's. */ 3330 if (sigsetsize != sizeof(sigset_t)) 3331 goto out; 3332 3333 if (act) { 3334 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa))) 3335 return -EFAULT; 3336 } 3337 3338 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL); 3339 3340 if (!ret && oact) { 3341 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa))) 3342 return -EFAULT; 3343 } 3344 out: 3345 return ret; 3346 } 3347 #ifdef CONFIG_COMPAT 3348 COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig, 3349 const struct compat_sigaction __user *, act, 3350 struct compat_sigaction __user *, oact, 3351 compat_size_t, sigsetsize) 3352 { 3353 struct k_sigaction new_ka, old_ka; 3354 compat_sigset_t mask; 3355 #ifdef __ARCH_HAS_SA_RESTORER 3356 compat_uptr_t restorer; 3357 #endif 3358 int ret; 3359 3360 /* XXX: Don't preclude handling different sized sigset_t's. */ 3361 if (sigsetsize != sizeof(compat_sigset_t)) 3362 return -EINVAL; 3363 3364 if (act) { 3365 compat_uptr_t handler; 3366 ret = get_user(handler, &act->sa_handler); 3367 new_ka.sa.sa_handler = compat_ptr(handler); 3368 #ifdef __ARCH_HAS_SA_RESTORER 3369 ret |= get_user(restorer, &act->sa_restorer); 3370 new_ka.sa.sa_restorer = compat_ptr(restorer); 3371 #endif 3372 ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask)); 3373 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags); 3374 if (ret) 3375 return -EFAULT; 3376 sigset_from_compat(&new_ka.sa.sa_mask, &mask); 3377 } 3378 3379 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); 3380 if (!ret && oact) { 3381 sigset_to_compat(&mask, &old_ka.sa.sa_mask); 3382 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), 3383 &oact->sa_handler); 3384 ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask)); 3385 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags); 3386 #ifdef __ARCH_HAS_SA_RESTORER 3387 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer), 3388 &oact->sa_restorer); 3389 #endif 3390 } 3391 return ret; 3392 } 3393 #endif 3394 #endif /* !CONFIG_ODD_RT_SIGACTION */ 3395 3396 #ifdef CONFIG_OLD_SIGACTION 3397 SYSCALL_DEFINE3(sigaction, int, sig, 3398 const struct old_sigaction __user *, act, 3399 struct old_sigaction __user *, oact) 3400 { 3401 struct k_sigaction new_ka, old_ka; 3402 int ret; 3403 3404 if (act) { 3405 old_sigset_t mask; 3406 if (!access_ok(VERIFY_READ, act, sizeof(*act)) || 3407 __get_user(new_ka.sa.sa_handler, &act->sa_handler) || 3408 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) || 3409 __get_user(new_ka.sa.sa_flags, &act->sa_flags) || 3410 __get_user(mask, &act->sa_mask)) 3411 return -EFAULT; 3412 #ifdef __ARCH_HAS_KA_RESTORER 3413 new_ka.ka_restorer = NULL; 3414 #endif 3415 siginitset(&new_ka.sa.sa_mask, mask); 3416 } 3417 3418 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); 3419 3420 if (!ret && oact) { 3421 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) || 3422 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) || 3423 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) || 3424 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) || 3425 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask)) 3426 return -EFAULT; 3427 } 3428 3429 return ret; 3430 } 3431 #endif 3432 #ifdef CONFIG_COMPAT_OLD_SIGACTION 3433 COMPAT_SYSCALL_DEFINE3(sigaction, int, sig, 3434 const struct compat_old_sigaction __user *, act, 3435 struct compat_old_sigaction __user *, oact) 3436 { 3437 struct k_sigaction new_ka, old_ka; 3438 int ret; 3439 compat_old_sigset_t mask; 3440 compat_uptr_t handler, restorer; 3441 3442 if (act) { 3443 if (!access_ok(VERIFY_READ, act, sizeof(*act)) || 3444 __get_user(handler, &act->sa_handler) || 3445 __get_user(restorer, &act->sa_restorer) || 3446 __get_user(new_ka.sa.sa_flags, &act->sa_flags) || 3447 __get_user(mask, &act->sa_mask)) 3448 return -EFAULT; 3449 3450 #ifdef __ARCH_HAS_KA_RESTORER 3451 new_ka.ka_restorer = NULL; 3452 #endif 3453 new_ka.sa.sa_handler = compat_ptr(handler); 3454 new_ka.sa.sa_restorer = compat_ptr(restorer); 3455 siginitset(&new_ka.sa.sa_mask, mask); 3456 } 3457 3458 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); 3459 3460 if (!ret && oact) { 3461 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) || 3462 __put_user(ptr_to_compat(old_ka.sa.sa_handler), 3463 &oact->sa_handler) || 3464 __put_user(ptr_to_compat(old_ka.sa.sa_restorer), 3465 &oact->sa_restorer) || 3466 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) || 3467 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask)) 3468 return -EFAULT; 3469 } 3470 return ret; 3471 } 3472 #endif 3473 3474 #ifdef CONFIG_SGETMASK_SYSCALL 3475 3476 /* 3477 * For backwards compatibility. Functionality superseded by sigprocmask. 3478 */ 3479 SYSCALL_DEFINE0(sgetmask) 3480 { 3481 /* SMP safe */ 3482 return current->blocked.sig[0]; 3483 } 3484 3485 SYSCALL_DEFINE1(ssetmask, int, newmask) 3486 { 3487 int old = current->blocked.sig[0]; 3488 sigset_t newset; 3489 3490 siginitset(&newset, newmask); 3491 set_current_blocked(&newset); 3492 3493 return old; 3494 } 3495 #endif /* CONFIG_SGETMASK_SYSCALL */ 3496 3497 #ifdef __ARCH_WANT_SYS_SIGNAL 3498 /* 3499 * For backwards compatibility. Functionality superseded by sigaction. 3500 */ 3501 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler) 3502 { 3503 struct k_sigaction new_sa, old_sa; 3504 int ret; 3505 3506 new_sa.sa.sa_handler = handler; 3507 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK; 3508 sigemptyset(&new_sa.sa.sa_mask); 3509 3510 ret = do_sigaction(sig, &new_sa, &old_sa); 3511 3512 return ret ? ret : (unsigned long)old_sa.sa.sa_handler; 3513 } 3514 #endif /* __ARCH_WANT_SYS_SIGNAL */ 3515 3516 #ifdef __ARCH_WANT_SYS_PAUSE 3517 3518 SYSCALL_DEFINE0(pause) 3519 { 3520 while (!signal_pending(current)) { 3521 __set_current_state(TASK_INTERRUPTIBLE); 3522 schedule(); 3523 } 3524 return -ERESTARTNOHAND; 3525 } 3526 3527 #endif 3528 3529 static int sigsuspend(sigset_t *set) 3530 { 3531 current->saved_sigmask = current->blocked; 3532 set_current_blocked(set); 3533 3534 while (!signal_pending(current)) { 3535 __set_current_state(TASK_INTERRUPTIBLE); 3536 schedule(); 3537 } 3538 set_restore_sigmask(); 3539 return -ERESTARTNOHAND; 3540 } 3541 3542 /** 3543 * sys_rt_sigsuspend - replace the signal mask for a value with the 3544 * @unewset value until a signal is received 3545 * @unewset: new signal mask value 3546 * @sigsetsize: size of sigset_t type 3547 */ 3548 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize) 3549 { 3550 sigset_t newset; 3551 3552 /* XXX: Don't preclude handling different sized sigset_t's. */ 3553 if (sigsetsize != sizeof(sigset_t)) 3554 return -EINVAL; 3555 3556 if (copy_from_user(&newset, unewset, sizeof(newset))) 3557 return -EFAULT; 3558 return sigsuspend(&newset); 3559 } 3560 3561 #ifdef CONFIG_COMPAT 3562 COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize) 3563 { 3564 #ifdef __BIG_ENDIAN 3565 sigset_t newset; 3566 compat_sigset_t newset32; 3567 3568 /* XXX: Don't preclude handling different sized sigset_t's. */ 3569 if (sigsetsize != sizeof(sigset_t)) 3570 return -EINVAL; 3571 3572 if (copy_from_user(&newset32, unewset, sizeof(compat_sigset_t))) 3573 return -EFAULT; 3574 sigset_from_compat(&newset, &newset32); 3575 return sigsuspend(&newset); 3576 #else 3577 /* on little-endian bitmaps don't care about granularity */ 3578 return sys_rt_sigsuspend((sigset_t __user *)unewset, sigsetsize); 3579 #endif 3580 } 3581 #endif 3582 3583 #ifdef CONFIG_OLD_SIGSUSPEND 3584 SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask) 3585 { 3586 sigset_t blocked; 3587 siginitset(&blocked, mask); 3588 return sigsuspend(&blocked); 3589 } 3590 #endif 3591 #ifdef CONFIG_OLD_SIGSUSPEND3 3592 SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask) 3593 { 3594 sigset_t blocked; 3595 siginitset(&blocked, mask); 3596 return sigsuspend(&blocked); 3597 } 3598 #endif 3599 3600 __weak const char *arch_vma_name(struct vm_area_struct *vma) 3601 { 3602 return NULL; 3603 } 3604 3605 void __init signals_init(void) 3606 { 3607 /* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */ 3608 BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE 3609 != offsetof(struct siginfo, _sifields._pad)); 3610 3611 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC); 3612 } 3613 3614 #ifdef CONFIG_KGDB_KDB 3615 #include <linux/kdb.h> 3616 /* 3617 * kdb_send_sig_info - Allows kdb to send signals without exposing 3618 * signal internals. This function checks if the required locks are 3619 * available before calling the main signal code, to avoid kdb 3620 * deadlocks. 3621 */ 3622 void 3623 kdb_send_sig_info(struct task_struct *t, struct siginfo *info) 3624 { 3625 static struct task_struct *kdb_prev_t; 3626 int sig, new_t; 3627 if (!spin_trylock(&t->sighand->siglock)) { 3628 kdb_printf("Can't do kill command now.\n" 3629 "The sigmask lock is held somewhere else in " 3630 "kernel, try again later\n"); 3631 return; 3632 } 3633 spin_unlock(&t->sighand->siglock); 3634 new_t = kdb_prev_t != t; 3635 kdb_prev_t = t; 3636 if (t->state != TASK_RUNNING && new_t) { 3637 kdb_printf("Process is not RUNNING, sending a signal from " 3638 "kdb risks deadlock\n" 3639 "on the run queue locks. " 3640 "The signal has _not_ been sent.\n" 3641 "Reissue the kill command if you want to risk " 3642 "the deadlock.\n"); 3643 return; 3644 } 3645 sig = info->si_signo; 3646 if (send_sig_info(sig, info, t)) 3647 kdb_printf("Fail to deliver Signal %d to process %d.\n", 3648 sig, t->pid); 3649 else 3650 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid); 3651 } 3652 #endif /* CONFIG_KGDB_KDB */ 3653