1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/kernel/signal.c 4 * 5 * Copyright (C) 1991, 1992 Linus Torvalds 6 * 7 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson 8 * 9 * 2003-06-02 Jim Houston - Concurrent Computer Corp. 10 * Changes to use preallocated sigqueue structures 11 * to allow signals to be sent reliably. 12 */ 13 14 #include <linux/slab.h> 15 #include <linux/export.h> 16 #include <linux/init.h> 17 #include <linux/sched/mm.h> 18 #include <linux/sched/user.h> 19 #include <linux/sched/debug.h> 20 #include <linux/sched/task.h> 21 #include <linux/sched/task_stack.h> 22 #include <linux/sched/cputime.h> 23 #include <linux/file.h> 24 #include <linux/fs.h> 25 #include <linux/proc_fs.h> 26 #include <linux/tty.h> 27 #include <linux/binfmts.h> 28 #include <linux/coredump.h> 29 #include <linux/security.h> 30 #include <linux/syscalls.h> 31 #include <linux/ptrace.h> 32 #include <linux/signal.h> 33 #include <linux/signalfd.h> 34 #include <linux/ratelimit.h> 35 #include <linux/tracehook.h> 36 #include <linux/capability.h> 37 #include <linux/freezer.h> 38 #include <linux/pid_namespace.h> 39 #include <linux/nsproxy.h> 40 #include <linux/user_namespace.h> 41 #include <linux/uprobes.h> 42 #include <linux/compat.h> 43 #include <linux/cn_proc.h> 44 #include <linux/compiler.h> 45 #include <linux/posix-timers.h> 46 #include <linux/livepatch.h> 47 #include <linux/cgroup.h> 48 #include <linux/audit.h> 49 50 #define CREATE_TRACE_POINTS 51 #include <trace/events/signal.h> 52 53 #include <asm/param.h> 54 #include <linux/uaccess.h> 55 #include <asm/unistd.h> 56 #include <asm/siginfo.h> 57 #include <asm/cacheflush.h> 58 59 /* 60 * SLAB caches for signal bits. 61 */ 62 63 static struct kmem_cache *sigqueue_cachep; 64 65 int print_fatal_signals __read_mostly; 66 67 static void __user *sig_handler(struct task_struct *t, int sig) 68 { 69 return t->sighand->action[sig - 1].sa.sa_handler; 70 } 71 72 static inline bool sig_handler_ignored(void __user *handler, int sig) 73 { 74 /* Is it explicitly or implicitly ignored? */ 75 return handler == SIG_IGN || 76 (handler == SIG_DFL && sig_kernel_ignore(sig)); 77 } 78 79 static bool sig_task_ignored(struct task_struct *t, int sig, bool force) 80 { 81 void __user *handler; 82 83 handler = sig_handler(t, sig); 84 85 /* SIGKILL and SIGSTOP may not be sent to the global init */ 86 if (unlikely(is_global_init(t) && sig_kernel_only(sig))) 87 return true; 88 89 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) && 90 handler == SIG_DFL && !(force && sig_kernel_only(sig))) 91 return true; 92 93 /* Only allow kernel generated signals to this kthread */ 94 if (unlikely((t->flags & PF_KTHREAD) && 95 (handler == SIG_KTHREAD_KERNEL) && !force)) 96 return true; 97 98 return sig_handler_ignored(handler, sig); 99 } 100 101 static bool sig_ignored(struct task_struct *t, int sig, bool force) 102 { 103 /* 104 * Blocked signals are never ignored, since the 105 * signal handler may change by the time it is 106 * unblocked. 107 */ 108 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig)) 109 return false; 110 111 /* 112 * Tracers may want to know about even ignored signal unless it 113 * is SIGKILL which can't be reported anyway but can be ignored 114 * by SIGNAL_UNKILLABLE task. 115 */ 116 if (t->ptrace && sig != SIGKILL) 117 return false; 118 119 return sig_task_ignored(t, sig, force); 120 } 121 122 /* 123 * Re-calculate pending state from the set of locally pending 124 * signals, globally pending signals, and blocked signals. 125 */ 126 static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked) 127 { 128 unsigned long ready; 129 long i; 130 131 switch (_NSIG_WORDS) { 132 default: 133 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;) 134 ready |= signal->sig[i] &~ blocked->sig[i]; 135 break; 136 137 case 4: ready = signal->sig[3] &~ blocked->sig[3]; 138 ready |= signal->sig[2] &~ blocked->sig[2]; 139 ready |= signal->sig[1] &~ blocked->sig[1]; 140 ready |= signal->sig[0] &~ blocked->sig[0]; 141 break; 142 143 case 2: ready = signal->sig[1] &~ blocked->sig[1]; 144 ready |= signal->sig[0] &~ blocked->sig[0]; 145 break; 146 147 case 1: ready = signal->sig[0] &~ blocked->sig[0]; 148 } 149 return ready != 0; 150 } 151 152 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b)) 153 154 static bool recalc_sigpending_tsk(struct task_struct *t) 155 { 156 if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) || 157 PENDING(&t->pending, &t->blocked) || 158 PENDING(&t->signal->shared_pending, &t->blocked) || 159 cgroup_task_frozen(t)) { 160 set_tsk_thread_flag(t, TIF_SIGPENDING); 161 return true; 162 } 163 164 /* 165 * We must never clear the flag in another thread, or in current 166 * when it's possible the current syscall is returning -ERESTART*. 167 * So we don't clear it here, and only callers who know they should do. 168 */ 169 return false; 170 } 171 172 /* 173 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up. 174 * This is superfluous when called on current, the wakeup is a harmless no-op. 175 */ 176 void recalc_sigpending_and_wake(struct task_struct *t) 177 { 178 if (recalc_sigpending_tsk(t)) 179 signal_wake_up(t, 0); 180 } 181 182 void recalc_sigpending(void) 183 { 184 if (!recalc_sigpending_tsk(current) && !freezing(current) && 185 !klp_patch_pending(current)) 186 clear_thread_flag(TIF_SIGPENDING); 187 188 } 189 EXPORT_SYMBOL(recalc_sigpending); 190 191 void calculate_sigpending(void) 192 { 193 /* Have any signals or users of TIF_SIGPENDING been delayed 194 * until after fork? 195 */ 196 spin_lock_irq(¤t->sighand->siglock); 197 set_tsk_thread_flag(current, TIF_SIGPENDING); 198 recalc_sigpending(); 199 spin_unlock_irq(¤t->sighand->siglock); 200 } 201 202 /* Given the mask, find the first available signal that should be serviced. */ 203 204 #define SYNCHRONOUS_MASK \ 205 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \ 206 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS)) 207 208 int next_signal(struct sigpending *pending, sigset_t *mask) 209 { 210 unsigned long i, *s, *m, x; 211 int sig = 0; 212 213 s = pending->signal.sig; 214 m = mask->sig; 215 216 /* 217 * Handle the first word specially: it contains the 218 * synchronous signals that need to be dequeued first. 219 */ 220 x = *s &~ *m; 221 if (x) { 222 if (x & SYNCHRONOUS_MASK) 223 x &= SYNCHRONOUS_MASK; 224 sig = ffz(~x) + 1; 225 return sig; 226 } 227 228 switch (_NSIG_WORDS) { 229 default: 230 for (i = 1; i < _NSIG_WORDS; ++i) { 231 x = *++s &~ *++m; 232 if (!x) 233 continue; 234 sig = ffz(~x) + i*_NSIG_BPW + 1; 235 break; 236 } 237 break; 238 239 case 2: 240 x = s[1] &~ m[1]; 241 if (!x) 242 break; 243 sig = ffz(~x) + _NSIG_BPW + 1; 244 break; 245 246 case 1: 247 /* Nothing to do */ 248 break; 249 } 250 251 return sig; 252 } 253 254 static inline void print_dropped_signal(int sig) 255 { 256 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10); 257 258 if (!print_fatal_signals) 259 return; 260 261 if (!__ratelimit(&ratelimit_state)) 262 return; 263 264 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n", 265 current->comm, current->pid, sig); 266 } 267 268 /** 269 * task_set_jobctl_pending - set jobctl pending bits 270 * @task: target task 271 * @mask: pending bits to set 272 * 273 * Clear @mask from @task->jobctl. @mask must be subset of 274 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK | 275 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is 276 * cleared. If @task is already being killed or exiting, this function 277 * becomes noop. 278 * 279 * CONTEXT: 280 * Must be called with @task->sighand->siglock held. 281 * 282 * RETURNS: 283 * %true if @mask is set, %false if made noop because @task was dying. 284 */ 285 bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask) 286 { 287 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME | 288 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING)); 289 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK)); 290 291 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING))) 292 return false; 293 294 if (mask & JOBCTL_STOP_SIGMASK) 295 task->jobctl &= ~JOBCTL_STOP_SIGMASK; 296 297 task->jobctl |= mask; 298 return true; 299 } 300 301 /** 302 * task_clear_jobctl_trapping - clear jobctl trapping bit 303 * @task: target task 304 * 305 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED. 306 * Clear it and wake up the ptracer. Note that we don't need any further 307 * locking. @task->siglock guarantees that @task->parent points to the 308 * ptracer. 309 * 310 * CONTEXT: 311 * Must be called with @task->sighand->siglock held. 312 */ 313 void task_clear_jobctl_trapping(struct task_struct *task) 314 { 315 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) { 316 task->jobctl &= ~JOBCTL_TRAPPING; 317 smp_mb(); /* advised by wake_up_bit() */ 318 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT); 319 } 320 } 321 322 /** 323 * task_clear_jobctl_pending - clear jobctl pending bits 324 * @task: target task 325 * @mask: pending bits to clear 326 * 327 * Clear @mask from @task->jobctl. @mask must be subset of 328 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other 329 * STOP bits are cleared together. 330 * 331 * If clearing of @mask leaves no stop or trap pending, this function calls 332 * task_clear_jobctl_trapping(). 333 * 334 * CONTEXT: 335 * Must be called with @task->sighand->siglock held. 336 */ 337 void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask) 338 { 339 BUG_ON(mask & ~JOBCTL_PENDING_MASK); 340 341 if (mask & JOBCTL_STOP_PENDING) 342 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED; 343 344 task->jobctl &= ~mask; 345 346 if (!(task->jobctl & JOBCTL_PENDING_MASK)) 347 task_clear_jobctl_trapping(task); 348 } 349 350 /** 351 * task_participate_group_stop - participate in a group stop 352 * @task: task participating in a group stop 353 * 354 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop. 355 * Group stop states are cleared and the group stop count is consumed if 356 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group 357 * stop, the appropriate `SIGNAL_*` flags are set. 358 * 359 * CONTEXT: 360 * Must be called with @task->sighand->siglock held. 361 * 362 * RETURNS: 363 * %true if group stop completion should be notified to the parent, %false 364 * otherwise. 365 */ 366 static bool task_participate_group_stop(struct task_struct *task) 367 { 368 struct signal_struct *sig = task->signal; 369 bool consume = task->jobctl & JOBCTL_STOP_CONSUME; 370 371 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING)); 372 373 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING); 374 375 if (!consume) 376 return false; 377 378 if (!WARN_ON_ONCE(sig->group_stop_count == 0)) 379 sig->group_stop_count--; 380 381 /* 382 * Tell the caller to notify completion iff we are entering into a 383 * fresh group stop. Read comment in do_signal_stop() for details. 384 */ 385 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) { 386 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED); 387 return true; 388 } 389 return false; 390 } 391 392 void task_join_group_stop(struct task_struct *task) 393 { 394 /* Have the new thread join an on-going signal group stop */ 395 unsigned long jobctl = current->jobctl; 396 if (jobctl & JOBCTL_STOP_PENDING) { 397 struct signal_struct *sig = current->signal; 398 unsigned long signr = jobctl & JOBCTL_STOP_SIGMASK; 399 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME; 400 if (task_set_jobctl_pending(task, signr | gstop)) { 401 sig->group_stop_count++; 402 } 403 } 404 } 405 406 /* 407 * allocate a new signal queue record 408 * - this may be called without locks if and only if t == current, otherwise an 409 * appropriate lock must be held to stop the target task from exiting 410 */ 411 static struct sigqueue * 412 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit) 413 { 414 struct sigqueue *q = NULL; 415 struct user_struct *user; 416 417 /* 418 * Protect access to @t credentials. This can go away when all 419 * callers hold rcu read lock. 420 */ 421 rcu_read_lock(); 422 user = get_uid(__task_cred(t)->user); 423 atomic_inc(&user->sigpending); 424 rcu_read_unlock(); 425 426 if (override_rlimit || 427 atomic_read(&user->sigpending) <= 428 task_rlimit(t, RLIMIT_SIGPENDING)) { 429 q = kmem_cache_alloc(sigqueue_cachep, flags); 430 } else { 431 print_dropped_signal(sig); 432 } 433 434 if (unlikely(q == NULL)) { 435 atomic_dec(&user->sigpending); 436 free_uid(user); 437 } else { 438 INIT_LIST_HEAD(&q->list); 439 q->flags = 0; 440 q->user = user; 441 } 442 443 return q; 444 } 445 446 static void __sigqueue_free(struct sigqueue *q) 447 { 448 if (q->flags & SIGQUEUE_PREALLOC) 449 return; 450 atomic_dec(&q->user->sigpending); 451 free_uid(q->user); 452 kmem_cache_free(sigqueue_cachep, q); 453 } 454 455 void flush_sigqueue(struct sigpending *queue) 456 { 457 struct sigqueue *q; 458 459 sigemptyset(&queue->signal); 460 while (!list_empty(&queue->list)) { 461 q = list_entry(queue->list.next, struct sigqueue , list); 462 list_del_init(&q->list); 463 __sigqueue_free(q); 464 } 465 } 466 467 /* 468 * Flush all pending signals for this kthread. 469 */ 470 void flush_signals(struct task_struct *t) 471 { 472 unsigned long flags; 473 474 spin_lock_irqsave(&t->sighand->siglock, flags); 475 clear_tsk_thread_flag(t, TIF_SIGPENDING); 476 flush_sigqueue(&t->pending); 477 flush_sigqueue(&t->signal->shared_pending); 478 spin_unlock_irqrestore(&t->sighand->siglock, flags); 479 } 480 EXPORT_SYMBOL(flush_signals); 481 482 #ifdef CONFIG_POSIX_TIMERS 483 static void __flush_itimer_signals(struct sigpending *pending) 484 { 485 sigset_t signal, retain; 486 struct sigqueue *q, *n; 487 488 signal = pending->signal; 489 sigemptyset(&retain); 490 491 list_for_each_entry_safe(q, n, &pending->list, list) { 492 int sig = q->info.si_signo; 493 494 if (likely(q->info.si_code != SI_TIMER)) { 495 sigaddset(&retain, sig); 496 } else { 497 sigdelset(&signal, sig); 498 list_del_init(&q->list); 499 __sigqueue_free(q); 500 } 501 } 502 503 sigorsets(&pending->signal, &signal, &retain); 504 } 505 506 void flush_itimer_signals(void) 507 { 508 struct task_struct *tsk = current; 509 unsigned long flags; 510 511 spin_lock_irqsave(&tsk->sighand->siglock, flags); 512 __flush_itimer_signals(&tsk->pending); 513 __flush_itimer_signals(&tsk->signal->shared_pending); 514 spin_unlock_irqrestore(&tsk->sighand->siglock, flags); 515 } 516 #endif 517 518 void ignore_signals(struct task_struct *t) 519 { 520 int i; 521 522 for (i = 0; i < _NSIG; ++i) 523 t->sighand->action[i].sa.sa_handler = SIG_IGN; 524 525 flush_signals(t); 526 } 527 528 /* 529 * Flush all handlers for a task. 530 */ 531 532 void 533 flush_signal_handlers(struct task_struct *t, int force_default) 534 { 535 int i; 536 struct k_sigaction *ka = &t->sighand->action[0]; 537 for (i = _NSIG ; i != 0 ; i--) { 538 if (force_default || ka->sa.sa_handler != SIG_IGN) 539 ka->sa.sa_handler = SIG_DFL; 540 ka->sa.sa_flags = 0; 541 #ifdef __ARCH_HAS_SA_RESTORER 542 ka->sa.sa_restorer = NULL; 543 #endif 544 sigemptyset(&ka->sa.sa_mask); 545 ka++; 546 } 547 } 548 549 bool unhandled_signal(struct task_struct *tsk, int sig) 550 { 551 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler; 552 if (is_global_init(tsk)) 553 return true; 554 555 if (handler != SIG_IGN && handler != SIG_DFL) 556 return false; 557 558 /* if ptraced, let the tracer determine */ 559 return !tsk->ptrace; 560 } 561 562 static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info, 563 bool *resched_timer) 564 { 565 struct sigqueue *q, *first = NULL; 566 567 /* 568 * Collect the siginfo appropriate to this signal. Check if 569 * there is another siginfo for the same signal. 570 */ 571 list_for_each_entry(q, &list->list, list) { 572 if (q->info.si_signo == sig) { 573 if (first) 574 goto still_pending; 575 first = q; 576 } 577 } 578 579 sigdelset(&list->signal, sig); 580 581 if (first) { 582 still_pending: 583 list_del_init(&first->list); 584 copy_siginfo(info, &first->info); 585 586 *resched_timer = 587 (first->flags & SIGQUEUE_PREALLOC) && 588 (info->si_code == SI_TIMER) && 589 (info->si_sys_private); 590 591 __sigqueue_free(first); 592 } else { 593 /* 594 * Ok, it wasn't in the queue. This must be 595 * a fast-pathed signal or we must have been 596 * out of queue space. So zero out the info. 597 */ 598 clear_siginfo(info); 599 info->si_signo = sig; 600 info->si_errno = 0; 601 info->si_code = SI_USER; 602 info->si_pid = 0; 603 info->si_uid = 0; 604 } 605 } 606 607 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask, 608 kernel_siginfo_t *info, bool *resched_timer) 609 { 610 int sig = next_signal(pending, mask); 611 612 if (sig) 613 collect_signal(sig, pending, info, resched_timer); 614 return sig; 615 } 616 617 /* 618 * Dequeue a signal and return the element to the caller, which is 619 * expected to free it. 620 * 621 * All callers have to hold the siglock. 622 */ 623 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, kernel_siginfo_t *info) 624 { 625 bool resched_timer = false; 626 int signr; 627 628 /* We only dequeue private signals from ourselves, we don't let 629 * signalfd steal them 630 */ 631 signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer); 632 if (!signr) { 633 signr = __dequeue_signal(&tsk->signal->shared_pending, 634 mask, info, &resched_timer); 635 #ifdef CONFIG_POSIX_TIMERS 636 /* 637 * itimer signal ? 638 * 639 * itimers are process shared and we restart periodic 640 * itimers in the signal delivery path to prevent DoS 641 * attacks in the high resolution timer case. This is 642 * compliant with the old way of self-restarting 643 * itimers, as the SIGALRM is a legacy signal and only 644 * queued once. Changing the restart behaviour to 645 * restart the timer in the signal dequeue path is 646 * reducing the timer noise on heavy loaded !highres 647 * systems too. 648 */ 649 if (unlikely(signr == SIGALRM)) { 650 struct hrtimer *tmr = &tsk->signal->real_timer; 651 652 if (!hrtimer_is_queued(tmr) && 653 tsk->signal->it_real_incr != 0) { 654 hrtimer_forward(tmr, tmr->base->get_time(), 655 tsk->signal->it_real_incr); 656 hrtimer_restart(tmr); 657 } 658 } 659 #endif 660 } 661 662 recalc_sigpending(); 663 if (!signr) 664 return 0; 665 666 if (unlikely(sig_kernel_stop(signr))) { 667 /* 668 * Set a marker that we have dequeued a stop signal. Our 669 * caller might release the siglock and then the pending 670 * stop signal it is about to process is no longer in the 671 * pending bitmasks, but must still be cleared by a SIGCONT 672 * (and overruled by a SIGKILL). So those cases clear this 673 * shared flag after we've set it. Note that this flag may 674 * remain set after the signal we return is ignored or 675 * handled. That doesn't matter because its only purpose 676 * is to alert stop-signal processing code when another 677 * processor has come along and cleared the flag. 678 */ 679 current->jobctl |= JOBCTL_STOP_DEQUEUED; 680 } 681 #ifdef CONFIG_POSIX_TIMERS 682 if (resched_timer) { 683 /* 684 * Release the siglock to ensure proper locking order 685 * of timer locks outside of siglocks. Note, we leave 686 * irqs disabled here, since the posix-timers code is 687 * about to disable them again anyway. 688 */ 689 spin_unlock(&tsk->sighand->siglock); 690 posixtimer_rearm(info); 691 spin_lock(&tsk->sighand->siglock); 692 693 /* Don't expose the si_sys_private value to userspace */ 694 info->si_sys_private = 0; 695 } 696 #endif 697 return signr; 698 } 699 EXPORT_SYMBOL_GPL(dequeue_signal); 700 701 static int dequeue_synchronous_signal(kernel_siginfo_t *info) 702 { 703 struct task_struct *tsk = current; 704 struct sigpending *pending = &tsk->pending; 705 struct sigqueue *q, *sync = NULL; 706 707 /* 708 * Might a synchronous signal be in the queue? 709 */ 710 if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK)) 711 return 0; 712 713 /* 714 * Return the first synchronous signal in the queue. 715 */ 716 list_for_each_entry(q, &pending->list, list) { 717 /* Synchronous signals have a postive si_code */ 718 if ((q->info.si_code > SI_USER) && 719 (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) { 720 sync = q; 721 goto next; 722 } 723 } 724 return 0; 725 next: 726 /* 727 * Check if there is another siginfo for the same signal. 728 */ 729 list_for_each_entry_continue(q, &pending->list, list) { 730 if (q->info.si_signo == sync->info.si_signo) 731 goto still_pending; 732 } 733 734 sigdelset(&pending->signal, sync->info.si_signo); 735 recalc_sigpending(); 736 still_pending: 737 list_del_init(&sync->list); 738 copy_siginfo(info, &sync->info); 739 __sigqueue_free(sync); 740 return info->si_signo; 741 } 742 743 /* 744 * Tell a process that it has a new active signal.. 745 * 746 * NOTE! we rely on the previous spin_lock to 747 * lock interrupts for us! We can only be called with 748 * "siglock" held, and the local interrupt must 749 * have been disabled when that got acquired! 750 * 751 * No need to set need_resched since signal event passing 752 * goes through ->blocked 753 */ 754 void signal_wake_up_state(struct task_struct *t, unsigned int state) 755 { 756 set_tsk_thread_flag(t, TIF_SIGPENDING); 757 /* 758 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable 759 * case. We don't check t->state here because there is a race with it 760 * executing another processor and just now entering stopped state. 761 * By using wake_up_state, we ensure the process will wake up and 762 * handle its death signal. 763 */ 764 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE)) 765 kick_process(t); 766 } 767 768 /* 769 * Remove signals in mask from the pending set and queue. 770 * Returns 1 if any signals were found. 771 * 772 * All callers must be holding the siglock. 773 */ 774 static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s) 775 { 776 struct sigqueue *q, *n; 777 sigset_t m; 778 779 sigandsets(&m, mask, &s->signal); 780 if (sigisemptyset(&m)) 781 return; 782 783 sigandnsets(&s->signal, &s->signal, mask); 784 list_for_each_entry_safe(q, n, &s->list, list) { 785 if (sigismember(mask, q->info.si_signo)) { 786 list_del_init(&q->list); 787 __sigqueue_free(q); 788 } 789 } 790 } 791 792 static inline int is_si_special(const struct kernel_siginfo *info) 793 { 794 return info <= SEND_SIG_PRIV; 795 } 796 797 static inline bool si_fromuser(const struct kernel_siginfo *info) 798 { 799 return info == SEND_SIG_NOINFO || 800 (!is_si_special(info) && SI_FROMUSER(info)); 801 } 802 803 /* 804 * called with RCU read lock from check_kill_permission() 805 */ 806 static bool kill_ok_by_cred(struct task_struct *t) 807 { 808 const struct cred *cred = current_cred(); 809 const struct cred *tcred = __task_cred(t); 810 811 return uid_eq(cred->euid, tcred->suid) || 812 uid_eq(cred->euid, tcred->uid) || 813 uid_eq(cred->uid, tcred->suid) || 814 uid_eq(cred->uid, tcred->uid) || 815 ns_capable(tcred->user_ns, CAP_KILL); 816 } 817 818 /* 819 * Bad permissions for sending the signal 820 * - the caller must hold the RCU read lock 821 */ 822 static int check_kill_permission(int sig, struct kernel_siginfo *info, 823 struct task_struct *t) 824 { 825 struct pid *sid; 826 int error; 827 828 if (!valid_signal(sig)) 829 return -EINVAL; 830 831 if (!si_fromuser(info)) 832 return 0; 833 834 error = audit_signal_info(sig, t); /* Let audit system see the signal */ 835 if (error) 836 return error; 837 838 if (!same_thread_group(current, t) && 839 !kill_ok_by_cred(t)) { 840 switch (sig) { 841 case SIGCONT: 842 sid = task_session(t); 843 /* 844 * We don't return the error if sid == NULL. The 845 * task was unhashed, the caller must notice this. 846 */ 847 if (!sid || sid == task_session(current)) 848 break; 849 /* fall through */ 850 default: 851 return -EPERM; 852 } 853 } 854 855 return security_task_kill(t, info, sig, NULL); 856 } 857 858 /** 859 * ptrace_trap_notify - schedule trap to notify ptracer 860 * @t: tracee wanting to notify tracer 861 * 862 * This function schedules sticky ptrace trap which is cleared on the next 863 * TRAP_STOP to notify ptracer of an event. @t must have been seized by 864 * ptracer. 865 * 866 * If @t is running, STOP trap will be taken. If trapped for STOP and 867 * ptracer is listening for events, tracee is woken up so that it can 868 * re-trap for the new event. If trapped otherwise, STOP trap will be 869 * eventually taken without returning to userland after the existing traps 870 * are finished by PTRACE_CONT. 871 * 872 * CONTEXT: 873 * Must be called with @task->sighand->siglock held. 874 */ 875 static void ptrace_trap_notify(struct task_struct *t) 876 { 877 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED)); 878 assert_spin_locked(&t->sighand->siglock); 879 880 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY); 881 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING); 882 } 883 884 /* 885 * Handle magic process-wide effects of stop/continue signals. Unlike 886 * the signal actions, these happen immediately at signal-generation 887 * time regardless of blocking, ignoring, or handling. This does the 888 * actual continuing for SIGCONT, but not the actual stopping for stop 889 * signals. The process stop is done as a signal action for SIG_DFL. 890 * 891 * Returns true if the signal should be actually delivered, otherwise 892 * it should be dropped. 893 */ 894 static bool prepare_signal(int sig, struct task_struct *p, bool force) 895 { 896 struct signal_struct *signal = p->signal; 897 struct task_struct *t; 898 sigset_t flush; 899 900 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) { 901 if (!(signal->flags & SIGNAL_GROUP_EXIT)) 902 return sig == SIGKILL; 903 /* 904 * The process is in the middle of dying, nothing to do. 905 */ 906 } else if (sig_kernel_stop(sig)) { 907 /* 908 * This is a stop signal. Remove SIGCONT from all queues. 909 */ 910 siginitset(&flush, sigmask(SIGCONT)); 911 flush_sigqueue_mask(&flush, &signal->shared_pending); 912 for_each_thread(p, t) 913 flush_sigqueue_mask(&flush, &t->pending); 914 } else if (sig == SIGCONT) { 915 unsigned int why; 916 /* 917 * Remove all stop signals from all queues, wake all threads. 918 */ 919 siginitset(&flush, SIG_KERNEL_STOP_MASK); 920 flush_sigqueue_mask(&flush, &signal->shared_pending); 921 for_each_thread(p, t) { 922 flush_sigqueue_mask(&flush, &t->pending); 923 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING); 924 if (likely(!(t->ptrace & PT_SEIZED))) 925 wake_up_state(t, __TASK_STOPPED); 926 else 927 ptrace_trap_notify(t); 928 } 929 930 /* 931 * Notify the parent with CLD_CONTINUED if we were stopped. 932 * 933 * If we were in the middle of a group stop, we pretend it 934 * was already finished, and then continued. Since SIGCHLD 935 * doesn't queue we report only CLD_STOPPED, as if the next 936 * CLD_CONTINUED was dropped. 937 */ 938 why = 0; 939 if (signal->flags & SIGNAL_STOP_STOPPED) 940 why |= SIGNAL_CLD_CONTINUED; 941 else if (signal->group_stop_count) 942 why |= SIGNAL_CLD_STOPPED; 943 944 if (why) { 945 /* 946 * The first thread which returns from do_signal_stop() 947 * will take ->siglock, notice SIGNAL_CLD_MASK, and 948 * notify its parent. See get_signal(). 949 */ 950 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED); 951 signal->group_stop_count = 0; 952 signal->group_exit_code = 0; 953 } 954 } 955 956 return !sig_ignored(p, sig, force); 957 } 958 959 /* 960 * Test if P wants to take SIG. After we've checked all threads with this, 961 * it's equivalent to finding no threads not blocking SIG. Any threads not 962 * blocking SIG were ruled out because they are not running and already 963 * have pending signals. Such threads will dequeue from the shared queue 964 * as soon as they're available, so putting the signal on the shared queue 965 * will be equivalent to sending it to one such thread. 966 */ 967 static inline bool wants_signal(int sig, struct task_struct *p) 968 { 969 if (sigismember(&p->blocked, sig)) 970 return false; 971 972 if (p->flags & PF_EXITING) 973 return false; 974 975 if (sig == SIGKILL) 976 return true; 977 978 if (task_is_stopped_or_traced(p)) 979 return false; 980 981 return task_curr(p) || !signal_pending(p); 982 } 983 984 static void complete_signal(int sig, struct task_struct *p, enum pid_type type) 985 { 986 struct signal_struct *signal = p->signal; 987 struct task_struct *t; 988 989 /* 990 * Now find a thread we can wake up to take the signal off the queue. 991 * 992 * If the main thread wants the signal, it gets first crack. 993 * Probably the least surprising to the average bear. 994 */ 995 if (wants_signal(sig, p)) 996 t = p; 997 else if ((type == PIDTYPE_PID) || thread_group_empty(p)) 998 /* 999 * There is just one thread and it does not need to be woken. 1000 * It will dequeue unblocked signals before it runs again. 1001 */ 1002 return; 1003 else { 1004 /* 1005 * Otherwise try to find a suitable thread. 1006 */ 1007 t = signal->curr_target; 1008 while (!wants_signal(sig, t)) { 1009 t = next_thread(t); 1010 if (t == signal->curr_target) 1011 /* 1012 * No thread needs to be woken. 1013 * Any eligible threads will see 1014 * the signal in the queue soon. 1015 */ 1016 return; 1017 } 1018 signal->curr_target = t; 1019 } 1020 1021 /* 1022 * Found a killable thread. If the signal will be fatal, 1023 * then start taking the whole group down immediately. 1024 */ 1025 if (sig_fatal(p, sig) && 1026 !(signal->flags & SIGNAL_GROUP_EXIT) && 1027 !sigismember(&t->real_blocked, sig) && 1028 (sig == SIGKILL || !p->ptrace)) { 1029 /* 1030 * This signal will be fatal to the whole group. 1031 */ 1032 if (!sig_kernel_coredump(sig)) { 1033 /* 1034 * Start a group exit and wake everybody up. 1035 * This way we don't have other threads 1036 * running and doing things after a slower 1037 * thread has the fatal signal pending. 1038 */ 1039 signal->flags = SIGNAL_GROUP_EXIT; 1040 signal->group_exit_code = sig; 1041 signal->group_stop_count = 0; 1042 t = p; 1043 do { 1044 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); 1045 sigaddset(&t->pending.signal, SIGKILL); 1046 signal_wake_up(t, 1); 1047 } while_each_thread(p, t); 1048 return; 1049 } 1050 } 1051 1052 /* 1053 * The signal is already in the shared-pending queue. 1054 * Tell the chosen thread to wake up and dequeue it. 1055 */ 1056 signal_wake_up(t, sig == SIGKILL); 1057 return; 1058 } 1059 1060 static inline bool legacy_queue(struct sigpending *signals, int sig) 1061 { 1062 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig); 1063 } 1064 1065 static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t, 1066 enum pid_type type, bool force) 1067 { 1068 struct sigpending *pending; 1069 struct sigqueue *q; 1070 int override_rlimit; 1071 int ret = 0, result; 1072 1073 assert_spin_locked(&t->sighand->siglock); 1074 1075 result = TRACE_SIGNAL_IGNORED; 1076 if (!prepare_signal(sig, t, force)) 1077 goto ret; 1078 1079 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending; 1080 /* 1081 * Short-circuit ignored signals and support queuing 1082 * exactly one non-rt signal, so that we can get more 1083 * detailed information about the cause of the signal. 1084 */ 1085 result = TRACE_SIGNAL_ALREADY_PENDING; 1086 if (legacy_queue(pending, sig)) 1087 goto ret; 1088 1089 result = TRACE_SIGNAL_DELIVERED; 1090 /* 1091 * Skip useless siginfo allocation for SIGKILL and kernel threads. 1092 */ 1093 if ((sig == SIGKILL) || (t->flags & PF_KTHREAD)) 1094 goto out_set; 1095 1096 /* 1097 * Real-time signals must be queued if sent by sigqueue, or 1098 * some other real-time mechanism. It is implementation 1099 * defined whether kill() does so. We attempt to do so, on 1100 * the principle of least surprise, but since kill is not 1101 * allowed to fail with EAGAIN when low on memory we just 1102 * make sure at least one signal gets delivered and don't 1103 * pass on the info struct. 1104 */ 1105 if (sig < SIGRTMIN) 1106 override_rlimit = (is_si_special(info) || info->si_code >= 0); 1107 else 1108 override_rlimit = 0; 1109 1110 q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit); 1111 if (q) { 1112 list_add_tail(&q->list, &pending->list); 1113 switch ((unsigned long) info) { 1114 case (unsigned long) SEND_SIG_NOINFO: 1115 clear_siginfo(&q->info); 1116 q->info.si_signo = sig; 1117 q->info.si_errno = 0; 1118 q->info.si_code = SI_USER; 1119 q->info.si_pid = task_tgid_nr_ns(current, 1120 task_active_pid_ns(t)); 1121 rcu_read_lock(); 1122 q->info.si_uid = 1123 from_kuid_munged(task_cred_xxx(t, user_ns), 1124 current_uid()); 1125 rcu_read_unlock(); 1126 break; 1127 case (unsigned long) SEND_SIG_PRIV: 1128 clear_siginfo(&q->info); 1129 q->info.si_signo = sig; 1130 q->info.si_errno = 0; 1131 q->info.si_code = SI_KERNEL; 1132 q->info.si_pid = 0; 1133 q->info.si_uid = 0; 1134 break; 1135 default: 1136 copy_siginfo(&q->info, info); 1137 break; 1138 } 1139 } else if (!is_si_special(info) && 1140 sig >= SIGRTMIN && info->si_code != SI_USER) { 1141 /* 1142 * Queue overflow, abort. We may abort if the 1143 * signal was rt and sent by user using something 1144 * other than kill(). 1145 */ 1146 result = TRACE_SIGNAL_OVERFLOW_FAIL; 1147 ret = -EAGAIN; 1148 goto ret; 1149 } else { 1150 /* 1151 * This is a silent loss of information. We still 1152 * send the signal, but the *info bits are lost. 1153 */ 1154 result = TRACE_SIGNAL_LOSE_INFO; 1155 } 1156 1157 out_set: 1158 signalfd_notify(t, sig); 1159 sigaddset(&pending->signal, sig); 1160 1161 /* Let multiprocess signals appear after on-going forks */ 1162 if (type > PIDTYPE_TGID) { 1163 struct multiprocess_signals *delayed; 1164 hlist_for_each_entry(delayed, &t->signal->multiprocess, node) { 1165 sigset_t *signal = &delayed->signal; 1166 /* Can't queue both a stop and a continue signal */ 1167 if (sig == SIGCONT) 1168 sigdelsetmask(signal, SIG_KERNEL_STOP_MASK); 1169 else if (sig_kernel_stop(sig)) 1170 sigdelset(signal, SIGCONT); 1171 sigaddset(signal, sig); 1172 } 1173 } 1174 1175 complete_signal(sig, t, type); 1176 ret: 1177 trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result); 1178 return ret; 1179 } 1180 1181 static inline bool has_si_pid_and_uid(struct kernel_siginfo *info) 1182 { 1183 bool ret = false; 1184 switch (siginfo_layout(info->si_signo, info->si_code)) { 1185 case SIL_KILL: 1186 case SIL_CHLD: 1187 case SIL_RT: 1188 ret = true; 1189 break; 1190 case SIL_TIMER: 1191 case SIL_POLL: 1192 case SIL_FAULT: 1193 case SIL_FAULT_MCEERR: 1194 case SIL_FAULT_BNDERR: 1195 case SIL_FAULT_PKUERR: 1196 case SIL_SYS: 1197 ret = false; 1198 break; 1199 } 1200 return ret; 1201 } 1202 1203 static int send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t, 1204 enum pid_type type) 1205 { 1206 /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */ 1207 bool force = false; 1208 1209 if (info == SEND_SIG_NOINFO) { 1210 /* Force if sent from an ancestor pid namespace */ 1211 force = !task_pid_nr_ns(current, task_active_pid_ns(t)); 1212 } else if (info == SEND_SIG_PRIV) { 1213 /* Don't ignore kernel generated signals */ 1214 force = true; 1215 } else if (has_si_pid_and_uid(info)) { 1216 /* SIGKILL and SIGSTOP is special or has ids */ 1217 struct user_namespace *t_user_ns; 1218 1219 rcu_read_lock(); 1220 t_user_ns = task_cred_xxx(t, user_ns); 1221 if (current_user_ns() != t_user_ns) { 1222 kuid_t uid = make_kuid(current_user_ns(), info->si_uid); 1223 info->si_uid = from_kuid_munged(t_user_ns, uid); 1224 } 1225 rcu_read_unlock(); 1226 1227 /* A kernel generated signal? */ 1228 force = (info->si_code == SI_KERNEL); 1229 1230 /* From an ancestor pid namespace? */ 1231 if (!task_pid_nr_ns(current, task_active_pid_ns(t))) { 1232 info->si_pid = 0; 1233 force = true; 1234 } 1235 } 1236 return __send_signal(sig, info, t, type, force); 1237 } 1238 1239 static void print_fatal_signal(int signr) 1240 { 1241 struct pt_regs *regs = signal_pt_regs(); 1242 pr_info("potentially unexpected fatal signal %d.\n", signr); 1243 1244 #if defined(__i386__) && !defined(__arch_um__) 1245 pr_info("code at %08lx: ", regs->ip); 1246 { 1247 int i; 1248 for (i = 0; i < 16; i++) { 1249 unsigned char insn; 1250 1251 if (get_user(insn, (unsigned char *)(regs->ip + i))) 1252 break; 1253 pr_cont("%02x ", insn); 1254 } 1255 } 1256 pr_cont("\n"); 1257 #endif 1258 preempt_disable(); 1259 show_regs(regs); 1260 preempt_enable(); 1261 } 1262 1263 static int __init setup_print_fatal_signals(char *str) 1264 { 1265 get_option (&str, &print_fatal_signals); 1266 1267 return 1; 1268 } 1269 1270 __setup("print-fatal-signals=", setup_print_fatal_signals); 1271 1272 int 1273 __group_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p) 1274 { 1275 return send_signal(sig, info, p, PIDTYPE_TGID); 1276 } 1277 1278 int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p, 1279 enum pid_type type) 1280 { 1281 unsigned long flags; 1282 int ret = -ESRCH; 1283 1284 if (lock_task_sighand(p, &flags)) { 1285 ret = send_signal(sig, info, p, type); 1286 unlock_task_sighand(p, &flags); 1287 } 1288 1289 return ret; 1290 } 1291 1292 /* 1293 * Force a signal that the process can't ignore: if necessary 1294 * we unblock the signal and change any SIG_IGN to SIG_DFL. 1295 * 1296 * Note: If we unblock the signal, we always reset it to SIG_DFL, 1297 * since we do not want to have a signal handler that was blocked 1298 * be invoked when user space had explicitly blocked it. 1299 * 1300 * We don't want to have recursive SIGSEGV's etc, for example, 1301 * that is why we also clear SIGNAL_UNKILLABLE. 1302 */ 1303 static int 1304 force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t) 1305 { 1306 unsigned long int flags; 1307 int ret, blocked, ignored; 1308 struct k_sigaction *action; 1309 int sig = info->si_signo; 1310 1311 spin_lock_irqsave(&t->sighand->siglock, flags); 1312 action = &t->sighand->action[sig-1]; 1313 ignored = action->sa.sa_handler == SIG_IGN; 1314 blocked = sigismember(&t->blocked, sig); 1315 if (blocked || ignored) { 1316 action->sa.sa_handler = SIG_DFL; 1317 if (blocked) { 1318 sigdelset(&t->blocked, sig); 1319 recalc_sigpending_and_wake(t); 1320 } 1321 } 1322 /* 1323 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect 1324 * debugging to leave init killable. 1325 */ 1326 if (action->sa.sa_handler == SIG_DFL && !t->ptrace) 1327 t->signal->flags &= ~SIGNAL_UNKILLABLE; 1328 ret = send_signal(sig, info, t, PIDTYPE_PID); 1329 spin_unlock_irqrestore(&t->sighand->siglock, flags); 1330 1331 return ret; 1332 } 1333 1334 int force_sig_info(struct kernel_siginfo *info) 1335 { 1336 return force_sig_info_to_task(info, current); 1337 } 1338 1339 /* 1340 * Nuke all other threads in the group. 1341 */ 1342 int zap_other_threads(struct task_struct *p) 1343 { 1344 struct task_struct *t = p; 1345 int count = 0; 1346 1347 p->signal->group_stop_count = 0; 1348 1349 while_each_thread(p, t) { 1350 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); 1351 count++; 1352 1353 /* Don't bother with already dead threads */ 1354 if (t->exit_state) 1355 continue; 1356 sigaddset(&t->pending.signal, SIGKILL); 1357 signal_wake_up(t, 1); 1358 } 1359 1360 return count; 1361 } 1362 1363 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk, 1364 unsigned long *flags) 1365 { 1366 struct sighand_struct *sighand; 1367 1368 rcu_read_lock(); 1369 for (;;) { 1370 sighand = rcu_dereference(tsk->sighand); 1371 if (unlikely(sighand == NULL)) 1372 break; 1373 1374 /* 1375 * This sighand can be already freed and even reused, but 1376 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which 1377 * initializes ->siglock: this slab can't go away, it has 1378 * the same object type, ->siglock can't be reinitialized. 1379 * 1380 * We need to ensure that tsk->sighand is still the same 1381 * after we take the lock, we can race with de_thread() or 1382 * __exit_signal(). In the latter case the next iteration 1383 * must see ->sighand == NULL. 1384 */ 1385 spin_lock_irqsave(&sighand->siglock, *flags); 1386 if (likely(sighand == tsk->sighand)) 1387 break; 1388 spin_unlock_irqrestore(&sighand->siglock, *flags); 1389 } 1390 rcu_read_unlock(); 1391 1392 return sighand; 1393 } 1394 1395 /* 1396 * send signal info to all the members of a group 1397 */ 1398 int group_send_sig_info(int sig, struct kernel_siginfo *info, 1399 struct task_struct *p, enum pid_type type) 1400 { 1401 int ret; 1402 1403 rcu_read_lock(); 1404 ret = check_kill_permission(sig, info, p); 1405 rcu_read_unlock(); 1406 1407 if (!ret && sig) 1408 ret = do_send_sig_info(sig, info, p, type); 1409 1410 return ret; 1411 } 1412 1413 /* 1414 * __kill_pgrp_info() sends a signal to a process group: this is what the tty 1415 * control characters do (^C, ^Z etc) 1416 * - the caller must hold at least a readlock on tasklist_lock 1417 */ 1418 int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp) 1419 { 1420 struct task_struct *p = NULL; 1421 int retval, success; 1422 1423 success = 0; 1424 retval = -ESRCH; 1425 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 1426 int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID); 1427 success |= !err; 1428 retval = err; 1429 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 1430 return success ? 0 : retval; 1431 } 1432 1433 int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid) 1434 { 1435 int error = -ESRCH; 1436 struct task_struct *p; 1437 1438 for (;;) { 1439 rcu_read_lock(); 1440 p = pid_task(pid, PIDTYPE_PID); 1441 if (p) 1442 error = group_send_sig_info(sig, info, p, PIDTYPE_TGID); 1443 rcu_read_unlock(); 1444 if (likely(!p || error != -ESRCH)) 1445 return error; 1446 1447 /* 1448 * The task was unhashed in between, try again. If it 1449 * is dead, pid_task() will return NULL, if we race with 1450 * de_thread() it will find the new leader. 1451 */ 1452 } 1453 } 1454 1455 static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid) 1456 { 1457 int error; 1458 rcu_read_lock(); 1459 error = kill_pid_info(sig, info, find_vpid(pid)); 1460 rcu_read_unlock(); 1461 return error; 1462 } 1463 1464 static inline bool kill_as_cred_perm(const struct cred *cred, 1465 struct task_struct *target) 1466 { 1467 const struct cred *pcred = __task_cred(target); 1468 1469 return uid_eq(cred->euid, pcred->suid) || 1470 uid_eq(cred->euid, pcred->uid) || 1471 uid_eq(cred->uid, pcred->suid) || 1472 uid_eq(cred->uid, pcred->uid); 1473 } 1474 1475 /* 1476 * The usb asyncio usage of siginfo is wrong. The glibc support 1477 * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT. 1478 * AKA after the generic fields: 1479 * kernel_pid_t si_pid; 1480 * kernel_uid32_t si_uid; 1481 * sigval_t si_value; 1482 * 1483 * Unfortunately when usb generates SI_ASYNCIO it assumes the layout 1484 * after the generic fields is: 1485 * void __user *si_addr; 1486 * 1487 * This is a practical problem when there is a 64bit big endian kernel 1488 * and a 32bit userspace. As the 32bit address will encoded in the low 1489 * 32bits of the pointer. Those low 32bits will be stored at higher 1490 * address than appear in a 32 bit pointer. So userspace will not 1491 * see the address it was expecting for it's completions. 1492 * 1493 * There is nothing in the encoding that can allow 1494 * copy_siginfo_to_user32 to detect this confusion of formats, so 1495 * handle this by requiring the caller of kill_pid_usb_asyncio to 1496 * notice when this situration takes place and to store the 32bit 1497 * pointer in sival_int, instead of sival_addr of the sigval_t addr 1498 * parameter. 1499 */ 1500 int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr, 1501 struct pid *pid, const struct cred *cred) 1502 { 1503 struct kernel_siginfo info; 1504 struct task_struct *p; 1505 unsigned long flags; 1506 int ret = -EINVAL; 1507 1508 clear_siginfo(&info); 1509 info.si_signo = sig; 1510 info.si_errno = errno; 1511 info.si_code = SI_ASYNCIO; 1512 *((sigval_t *)&info.si_pid) = addr; 1513 1514 if (!valid_signal(sig)) 1515 return ret; 1516 1517 rcu_read_lock(); 1518 p = pid_task(pid, PIDTYPE_PID); 1519 if (!p) { 1520 ret = -ESRCH; 1521 goto out_unlock; 1522 } 1523 if (!kill_as_cred_perm(cred, p)) { 1524 ret = -EPERM; 1525 goto out_unlock; 1526 } 1527 ret = security_task_kill(p, &info, sig, cred); 1528 if (ret) 1529 goto out_unlock; 1530 1531 if (sig) { 1532 if (lock_task_sighand(p, &flags)) { 1533 ret = __send_signal(sig, &info, p, PIDTYPE_TGID, false); 1534 unlock_task_sighand(p, &flags); 1535 } else 1536 ret = -ESRCH; 1537 } 1538 out_unlock: 1539 rcu_read_unlock(); 1540 return ret; 1541 } 1542 EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio); 1543 1544 /* 1545 * kill_something_info() interprets pid in interesting ways just like kill(2). 1546 * 1547 * POSIX specifies that kill(-1,sig) is unspecified, but what we have 1548 * is probably wrong. Should make it like BSD or SYSV. 1549 */ 1550 1551 static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid) 1552 { 1553 int ret; 1554 1555 if (pid > 0) { 1556 rcu_read_lock(); 1557 ret = kill_pid_info(sig, info, find_vpid(pid)); 1558 rcu_read_unlock(); 1559 return ret; 1560 } 1561 1562 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */ 1563 if (pid == INT_MIN) 1564 return -ESRCH; 1565 1566 read_lock(&tasklist_lock); 1567 if (pid != -1) { 1568 ret = __kill_pgrp_info(sig, info, 1569 pid ? find_vpid(-pid) : task_pgrp(current)); 1570 } else { 1571 int retval = 0, count = 0; 1572 struct task_struct * p; 1573 1574 for_each_process(p) { 1575 if (task_pid_vnr(p) > 1 && 1576 !same_thread_group(p, current)) { 1577 int err = group_send_sig_info(sig, info, p, 1578 PIDTYPE_MAX); 1579 ++count; 1580 if (err != -EPERM) 1581 retval = err; 1582 } 1583 } 1584 ret = count ? retval : -ESRCH; 1585 } 1586 read_unlock(&tasklist_lock); 1587 1588 return ret; 1589 } 1590 1591 /* 1592 * These are for backward compatibility with the rest of the kernel source. 1593 */ 1594 1595 int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p) 1596 { 1597 /* 1598 * Make sure legacy kernel users don't send in bad values 1599 * (normal paths check this in check_kill_permission). 1600 */ 1601 if (!valid_signal(sig)) 1602 return -EINVAL; 1603 1604 return do_send_sig_info(sig, info, p, PIDTYPE_PID); 1605 } 1606 EXPORT_SYMBOL(send_sig_info); 1607 1608 #define __si_special(priv) \ 1609 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO) 1610 1611 int 1612 send_sig(int sig, struct task_struct *p, int priv) 1613 { 1614 return send_sig_info(sig, __si_special(priv), p); 1615 } 1616 EXPORT_SYMBOL(send_sig); 1617 1618 void force_sig(int sig) 1619 { 1620 struct kernel_siginfo info; 1621 1622 clear_siginfo(&info); 1623 info.si_signo = sig; 1624 info.si_errno = 0; 1625 info.si_code = SI_KERNEL; 1626 info.si_pid = 0; 1627 info.si_uid = 0; 1628 force_sig_info(&info); 1629 } 1630 EXPORT_SYMBOL(force_sig); 1631 1632 /* 1633 * When things go south during signal handling, we 1634 * will force a SIGSEGV. And if the signal that caused 1635 * the problem was already a SIGSEGV, we'll want to 1636 * make sure we don't even try to deliver the signal.. 1637 */ 1638 void force_sigsegv(int sig) 1639 { 1640 struct task_struct *p = current; 1641 1642 if (sig == SIGSEGV) { 1643 unsigned long flags; 1644 spin_lock_irqsave(&p->sighand->siglock, flags); 1645 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL; 1646 spin_unlock_irqrestore(&p->sighand->siglock, flags); 1647 } 1648 force_sig(SIGSEGV); 1649 } 1650 1651 int force_sig_fault_to_task(int sig, int code, void __user *addr 1652 ___ARCH_SI_TRAPNO(int trapno) 1653 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr) 1654 , struct task_struct *t) 1655 { 1656 struct kernel_siginfo info; 1657 1658 clear_siginfo(&info); 1659 info.si_signo = sig; 1660 info.si_errno = 0; 1661 info.si_code = code; 1662 info.si_addr = addr; 1663 #ifdef __ARCH_SI_TRAPNO 1664 info.si_trapno = trapno; 1665 #endif 1666 #ifdef __ia64__ 1667 info.si_imm = imm; 1668 info.si_flags = flags; 1669 info.si_isr = isr; 1670 #endif 1671 return force_sig_info_to_task(&info, t); 1672 } 1673 1674 int force_sig_fault(int sig, int code, void __user *addr 1675 ___ARCH_SI_TRAPNO(int trapno) 1676 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)) 1677 { 1678 return force_sig_fault_to_task(sig, code, addr 1679 ___ARCH_SI_TRAPNO(trapno) 1680 ___ARCH_SI_IA64(imm, flags, isr), current); 1681 } 1682 1683 int send_sig_fault(int sig, int code, void __user *addr 1684 ___ARCH_SI_TRAPNO(int trapno) 1685 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr) 1686 , struct task_struct *t) 1687 { 1688 struct kernel_siginfo info; 1689 1690 clear_siginfo(&info); 1691 info.si_signo = sig; 1692 info.si_errno = 0; 1693 info.si_code = code; 1694 info.si_addr = addr; 1695 #ifdef __ARCH_SI_TRAPNO 1696 info.si_trapno = trapno; 1697 #endif 1698 #ifdef __ia64__ 1699 info.si_imm = imm; 1700 info.si_flags = flags; 1701 info.si_isr = isr; 1702 #endif 1703 return send_sig_info(info.si_signo, &info, t); 1704 } 1705 1706 int force_sig_mceerr(int code, void __user *addr, short lsb) 1707 { 1708 struct kernel_siginfo info; 1709 1710 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR)); 1711 clear_siginfo(&info); 1712 info.si_signo = SIGBUS; 1713 info.si_errno = 0; 1714 info.si_code = code; 1715 info.si_addr = addr; 1716 info.si_addr_lsb = lsb; 1717 return force_sig_info(&info); 1718 } 1719 1720 int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t) 1721 { 1722 struct kernel_siginfo info; 1723 1724 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR)); 1725 clear_siginfo(&info); 1726 info.si_signo = SIGBUS; 1727 info.si_errno = 0; 1728 info.si_code = code; 1729 info.si_addr = addr; 1730 info.si_addr_lsb = lsb; 1731 return send_sig_info(info.si_signo, &info, t); 1732 } 1733 EXPORT_SYMBOL(send_sig_mceerr); 1734 1735 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper) 1736 { 1737 struct kernel_siginfo info; 1738 1739 clear_siginfo(&info); 1740 info.si_signo = SIGSEGV; 1741 info.si_errno = 0; 1742 info.si_code = SEGV_BNDERR; 1743 info.si_addr = addr; 1744 info.si_lower = lower; 1745 info.si_upper = upper; 1746 return force_sig_info(&info); 1747 } 1748 1749 #ifdef SEGV_PKUERR 1750 int force_sig_pkuerr(void __user *addr, u32 pkey) 1751 { 1752 struct kernel_siginfo info; 1753 1754 clear_siginfo(&info); 1755 info.si_signo = SIGSEGV; 1756 info.si_errno = 0; 1757 info.si_code = SEGV_PKUERR; 1758 info.si_addr = addr; 1759 info.si_pkey = pkey; 1760 return force_sig_info(&info); 1761 } 1762 #endif 1763 1764 /* For the crazy architectures that include trap information in 1765 * the errno field, instead of an actual errno value. 1766 */ 1767 int force_sig_ptrace_errno_trap(int errno, void __user *addr) 1768 { 1769 struct kernel_siginfo info; 1770 1771 clear_siginfo(&info); 1772 info.si_signo = SIGTRAP; 1773 info.si_errno = errno; 1774 info.si_code = TRAP_HWBKPT; 1775 info.si_addr = addr; 1776 return force_sig_info(&info); 1777 } 1778 1779 int kill_pgrp(struct pid *pid, int sig, int priv) 1780 { 1781 int ret; 1782 1783 read_lock(&tasklist_lock); 1784 ret = __kill_pgrp_info(sig, __si_special(priv), pid); 1785 read_unlock(&tasklist_lock); 1786 1787 return ret; 1788 } 1789 EXPORT_SYMBOL(kill_pgrp); 1790 1791 int kill_pid(struct pid *pid, int sig, int priv) 1792 { 1793 return kill_pid_info(sig, __si_special(priv), pid); 1794 } 1795 EXPORT_SYMBOL(kill_pid); 1796 1797 /* 1798 * These functions support sending signals using preallocated sigqueue 1799 * structures. This is needed "because realtime applications cannot 1800 * afford to lose notifications of asynchronous events, like timer 1801 * expirations or I/O completions". In the case of POSIX Timers 1802 * we allocate the sigqueue structure from the timer_create. If this 1803 * allocation fails we are able to report the failure to the application 1804 * with an EAGAIN error. 1805 */ 1806 struct sigqueue *sigqueue_alloc(void) 1807 { 1808 struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0); 1809 1810 if (q) 1811 q->flags |= SIGQUEUE_PREALLOC; 1812 1813 return q; 1814 } 1815 1816 void sigqueue_free(struct sigqueue *q) 1817 { 1818 unsigned long flags; 1819 spinlock_t *lock = ¤t->sighand->siglock; 1820 1821 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); 1822 /* 1823 * We must hold ->siglock while testing q->list 1824 * to serialize with collect_signal() or with 1825 * __exit_signal()->flush_sigqueue(). 1826 */ 1827 spin_lock_irqsave(lock, flags); 1828 q->flags &= ~SIGQUEUE_PREALLOC; 1829 /* 1830 * If it is queued it will be freed when dequeued, 1831 * like the "regular" sigqueue. 1832 */ 1833 if (!list_empty(&q->list)) 1834 q = NULL; 1835 spin_unlock_irqrestore(lock, flags); 1836 1837 if (q) 1838 __sigqueue_free(q); 1839 } 1840 1841 int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type) 1842 { 1843 int sig = q->info.si_signo; 1844 struct sigpending *pending; 1845 struct task_struct *t; 1846 unsigned long flags; 1847 int ret, result; 1848 1849 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); 1850 1851 ret = -1; 1852 rcu_read_lock(); 1853 t = pid_task(pid, type); 1854 if (!t || !likely(lock_task_sighand(t, &flags))) 1855 goto ret; 1856 1857 ret = 1; /* the signal is ignored */ 1858 result = TRACE_SIGNAL_IGNORED; 1859 if (!prepare_signal(sig, t, false)) 1860 goto out; 1861 1862 ret = 0; 1863 if (unlikely(!list_empty(&q->list))) { 1864 /* 1865 * If an SI_TIMER entry is already queue just increment 1866 * the overrun count. 1867 */ 1868 BUG_ON(q->info.si_code != SI_TIMER); 1869 q->info.si_overrun++; 1870 result = TRACE_SIGNAL_ALREADY_PENDING; 1871 goto out; 1872 } 1873 q->info.si_overrun = 0; 1874 1875 signalfd_notify(t, sig); 1876 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending; 1877 list_add_tail(&q->list, &pending->list); 1878 sigaddset(&pending->signal, sig); 1879 complete_signal(sig, t, type); 1880 result = TRACE_SIGNAL_DELIVERED; 1881 out: 1882 trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result); 1883 unlock_task_sighand(t, &flags); 1884 ret: 1885 rcu_read_unlock(); 1886 return ret; 1887 } 1888 1889 static void do_notify_pidfd(struct task_struct *task) 1890 { 1891 struct pid *pid; 1892 1893 WARN_ON(task->exit_state == 0); 1894 pid = task_pid(task); 1895 wake_up_all(&pid->wait_pidfd); 1896 } 1897 1898 /* 1899 * Let a parent know about the death of a child. 1900 * For a stopped/continued status change, use do_notify_parent_cldstop instead. 1901 * 1902 * Returns true if our parent ignored us and so we've switched to 1903 * self-reaping. 1904 */ 1905 bool do_notify_parent(struct task_struct *tsk, int sig) 1906 { 1907 struct kernel_siginfo info; 1908 unsigned long flags; 1909 struct sighand_struct *psig; 1910 bool autoreap = false; 1911 u64 utime, stime; 1912 1913 BUG_ON(sig == -1); 1914 1915 /* do_notify_parent_cldstop should have been called instead. */ 1916 BUG_ON(task_is_stopped_or_traced(tsk)); 1917 1918 BUG_ON(!tsk->ptrace && 1919 (tsk->group_leader != tsk || !thread_group_empty(tsk))); 1920 1921 /* Wake up all pidfd waiters */ 1922 do_notify_pidfd(tsk); 1923 1924 if (sig != SIGCHLD) { 1925 /* 1926 * This is only possible if parent == real_parent. 1927 * Check if it has changed security domain. 1928 */ 1929 if (tsk->parent_exec_id != tsk->parent->self_exec_id) 1930 sig = SIGCHLD; 1931 } 1932 1933 clear_siginfo(&info); 1934 info.si_signo = sig; 1935 info.si_errno = 0; 1936 /* 1937 * We are under tasklist_lock here so our parent is tied to 1938 * us and cannot change. 1939 * 1940 * task_active_pid_ns will always return the same pid namespace 1941 * until a task passes through release_task. 1942 * 1943 * write_lock() currently calls preempt_disable() which is the 1944 * same as rcu_read_lock(), but according to Oleg, this is not 1945 * correct to rely on this 1946 */ 1947 rcu_read_lock(); 1948 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent)); 1949 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns), 1950 task_uid(tsk)); 1951 rcu_read_unlock(); 1952 1953 task_cputime(tsk, &utime, &stime); 1954 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime); 1955 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime); 1956 1957 info.si_status = tsk->exit_code & 0x7f; 1958 if (tsk->exit_code & 0x80) 1959 info.si_code = CLD_DUMPED; 1960 else if (tsk->exit_code & 0x7f) 1961 info.si_code = CLD_KILLED; 1962 else { 1963 info.si_code = CLD_EXITED; 1964 info.si_status = tsk->exit_code >> 8; 1965 } 1966 1967 psig = tsk->parent->sighand; 1968 spin_lock_irqsave(&psig->siglock, flags); 1969 if (!tsk->ptrace && sig == SIGCHLD && 1970 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN || 1971 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) { 1972 /* 1973 * We are exiting and our parent doesn't care. POSIX.1 1974 * defines special semantics for setting SIGCHLD to SIG_IGN 1975 * or setting the SA_NOCLDWAIT flag: we should be reaped 1976 * automatically and not left for our parent's wait4 call. 1977 * Rather than having the parent do it as a magic kind of 1978 * signal handler, we just set this to tell do_exit that we 1979 * can be cleaned up without becoming a zombie. Note that 1980 * we still call __wake_up_parent in this case, because a 1981 * blocked sys_wait4 might now return -ECHILD. 1982 * 1983 * Whether we send SIGCHLD or not for SA_NOCLDWAIT 1984 * is implementation-defined: we do (if you don't want 1985 * it, just use SIG_IGN instead). 1986 */ 1987 autoreap = true; 1988 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) 1989 sig = 0; 1990 } 1991 if (valid_signal(sig) && sig) 1992 __group_send_sig_info(sig, &info, tsk->parent); 1993 __wake_up_parent(tsk, tsk->parent); 1994 spin_unlock_irqrestore(&psig->siglock, flags); 1995 1996 return autoreap; 1997 } 1998 1999 /** 2000 * do_notify_parent_cldstop - notify parent of stopped/continued state change 2001 * @tsk: task reporting the state change 2002 * @for_ptracer: the notification is for ptracer 2003 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report 2004 * 2005 * Notify @tsk's parent that the stopped/continued state has changed. If 2006 * @for_ptracer is %false, @tsk's group leader notifies to its real parent. 2007 * If %true, @tsk reports to @tsk->parent which should be the ptracer. 2008 * 2009 * CONTEXT: 2010 * Must be called with tasklist_lock at least read locked. 2011 */ 2012 static void do_notify_parent_cldstop(struct task_struct *tsk, 2013 bool for_ptracer, int why) 2014 { 2015 struct kernel_siginfo info; 2016 unsigned long flags; 2017 struct task_struct *parent; 2018 struct sighand_struct *sighand; 2019 u64 utime, stime; 2020 2021 if (for_ptracer) { 2022 parent = tsk->parent; 2023 } else { 2024 tsk = tsk->group_leader; 2025 parent = tsk->real_parent; 2026 } 2027 2028 clear_siginfo(&info); 2029 info.si_signo = SIGCHLD; 2030 info.si_errno = 0; 2031 /* 2032 * see comment in do_notify_parent() about the following 4 lines 2033 */ 2034 rcu_read_lock(); 2035 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent)); 2036 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk)); 2037 rcu_read_unlock(); 2038 2039 task_cputime(tsk, &utime, &stime); 2040 info.si_utime = nsec_to_clock_t(utime); 2041 info.si_stime = nsec_to_clock_t(stime); 2042 2043 info.si_code = why; 2044 switch (why) { 2045 case CLD_CONTINUED: 2046 info.si_status = SIGCONT; 2047 break; 2048 case CLD_STOPPED: 2049 info.si_status = tsk->signal->group_exit_code & 0x7f; 2050 break; 2051 case CLD_TRAPPED: 2052 info.si_status = tsk->exit_code & 0x7f; 2053 break; 2054 default: 2055 BUG(); 2056 } 2057 2058 sighand = parent->sighand; 2059 spin_lock_irqsave(&sighand->siglock, flags); 2060 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN && 2061 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP)) 2062 __group_send_sig_info(SIGCHLD, &info, parent); 2063 /* 2064 * Even if SIGCHLD is not generated, we must wake up wait4 calls. 2065 */ 2066 __wake_up_parent(tsk, parent); 2067 spin_unlock_irqrestore(&sighand->siglock, flags); 2068 } 2069 2070 static inline bool may_ptrace_stop(void) 2071 { 2072 if (!likely(current->ptrace)) 2073 return false; 2074 /* 2075 * Are we in the middle of do_coredump? 2076 * If so and our tracer is also part of the coredump stopping 2077 * is a deadlock situation, and pointless because our tracer 2078 * is dead so don't allow us to stop. 2079 * If SIGKILL was already sent before the caller unlocked 2080 * ->siglock we must see ->core_state != NULL. Otherwise it 2081 * is safe to enter schedule(). 2082 * 2083 * This is almost outdated, a task with the pending SIGKILL can't 2084 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported 2085 * after SIGKILL was already dequeued. 2086 */ 2087 if (unlikely(current->mm->core_state) && 2088 unlikely(current->mm == current->parent->mm)) 2089 return false; 2090 2091 return true; 2092 } 2093 2094 /* 2095 * Return non-zero if there is a SIGKILL that should be waking us up. 2096 * Called with the siglock held. 2097 */ 2098 static bool sigkill_pending(struct task_struct *tsk) 2099 { 2100 return sigismember(&tsk->pending.signal, SIGKILL) || 2101 sigismember(&tsk->signal->shared_pending.signal, SIGKILL); 2102 } 2103 2104 /* 2105 * This must be called with current->sighand->siglock held. 2106 * 2107 * This should be the path for all ptrace stops. 2108 * We always set current->last_siginfo while stopped here. 2109 * That makes it a way to test a stopped process for 2110 * being ptrace-stopped vs being job-control-stopped. 2111 * 2112 * If we actually decide not to stop at all because the tracer 2113 * is gone, we keep current->exit_code unless clear_code. 2114 */ 2115 static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t *info) 2116 __releases(¤t->sighand->siglock) 2117 __acquires(¤t->sighand->siglock) 2118 { 2119 bool gstop_done = false; 2120 2121 if (arch_ptrace_stop_needed(exit_code, info)) { 2122 /* 2123 * The arch code has something special to do before a 2124 * ptrace stop. This is allowed to block, e.g. for faults 2125 * on user stack pages. We can't keep the siglock while 2126 * calling arch_ptrace_stop, so we must release it now. 2127 * To preserve proper semantics, we must do this before 2128 * any signal bookkeeping like checking group_stop_count. 2129 * Meanwhile, a SIGKILL could come in before we retake the 2130 * siglock. That must prevent us from sleeping in TASK_TRACED. 2131 * So after regaining the lock, we must check for SIGKILL. 2132 */ 2133 spin_unlock_irq(¤t->sighand->siglock); 2134 arch_ptrace_stop(exit_code, info); 2135 spin_lock_irq(¤t->sighand->siglock); 2136 if (sigkill_pending(current)) 2137 return; 2138 } 2139 2140 set_special_state(TASK_TRACED); 2141 2142 /* 2143 * We're committing to trapping. TRACED should be visible before 2144 * TRAPPING is cleared; otherwise, the tracer might fail do_wait(). 2145 * Also, transition to TRACED and updates to ->jobctl should be 2146 * atomic with respect to siglock and should be done after the arch 2147 * hook as siglock is released and regrabbed across it. 2148 * 2149 * TRACER TRACEE 2150 * 2151 * ptrace_attach() 2152 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED) 2153 * do_wait() 2154 * set_current_state() smp_wmb(); 2155 * ptrace_do_wait() 2156 * wait_task_stopped() 2157 * task_stopped_code() 2158 * [L] task_is_traced() [S] task_clear_jobctl_trapping(); 2159 */ 2160 smp_wmb(); 2161 2162 current->last_siginfo = info; 2163 current->exit_code = exit_code; 2164 2165 /* 2166 * If @why is CLD_STOPPED, we're trapping to participate in a group 2167 * stop. Do the bookkeeping. Note that if SIGCONT was delievered 2168 * across siglock relocks since INTERRUPT was scheduled, PENDING 2169 * could be clear now. We act as if SIGCONT is received after 2170 * TASK_TRACED is entered - ignore it. 2171 */ 2172 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING)) 2173 gstop_done = task_participate_group_stop(current); 2174 2175 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */ 2176 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP); 2177 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP) 2178 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY); 2179 2180 /* entering a trap, clear TRAPPING */ 2181 task_clear_jobctl_trapping(current); 2182 2183 spin_unlock_irq(¤t->sighand->siglock); 2184 read_lock(&tasklist_lock); 2185 if (may_ptrace_stop()) { 2186 /* 2187 * Notify parents of the stop. 2188 * 2189 * While ptraced, there are two parents - the ptracer and 2190 * the real_parent of the group_leader. The ptracer should 2191 * know about every stop while the real parent is only 2192 * interested in the completion of group stop. The states 2193 * for the two don't interact with each other. Notify 2194 * separately unless they're gonna be duplicates. 2195 */ 2196 do_notify_parent_cldstop(current, true, why); 2197 if (gstop_done && ptrace_reparented(current)) 2198 do_notify_parent_cldstop(current, false, why); 2199 2200 /* 2201 * Don't want to allow preemption here, because 2202 * sys_ptrace() needs this task to be inactive. 2203 * 2204 * XXX: implement read_unlock_no_resched(). 2205 */ 2206 preempt_disable(); 2207 read_unlock(&tasklist_lock); 2208 preempt_enable_no_resched(); 2209 cgroup_enter_frozen(); 2210 freezable_schedule(); 2211 cgroup_leave_frozen(true); 2212 } else { 2213 /* 2214 * By the time we got the lock, our tracer went away. 2215 * Don't drop the lock yet, another tracer may come. 2216 * 2217 * If @gstop_done, the ptracer went away between group stop 2218 * completion and here. During detach, it would have set 2219 * JOBCTL_STOP_PENDING on us and we'll re-enter 2220 * TASK_STOPPED in do_signal_stop() on return, so notifying 2221 * the real parent of the group stop completion is enough. 2222 */ 2223 if (gstop_done) 2224 do_notify_parent_cldstop(current, false, why); 2225 2226 /* tasklist protects us from ptrace_freeze_traced() */ 2227 __set_current_state(TASK_RUNNING); 2228 if (clear_code) 2229 current->exit_code = 0; 2230 read_unlock(&tasklist_lock); 2231 } 2232 2233 /* 2234 * We are back. Now reacquire the siglock before touching 2235 * last_siginfo, so that we are sure to have synchronized with 2236 * any signal-sending on another CPU that wants to examine it. 2237 */ 2238 spin_lock_irq(¤t->sighand->siglock); 2239 current->last_siginfo = NULL; 2240 2241 /* LISTENING can be set only during STOP traps, clear it */ 2242 current->jobctl &= ~JOBCTL_LISTENING; 2243 2244 /* 2245 * Queued signals ignored us while we were stopped for tracing. 2246 * So check for any that we should take before resuming user mode. 2247 * This sets TIF_SIGPENDING, but never clears it. 2248 */ 2249 recalc_sigpending_tsk(current); 2250 } 2251 2252 static void ptrace_do_notify(int signr, int exit_code, int why) 2253 { 2254 kernel_siginfo_t info; 2255 2256 clear_siginfo(&info); 2257 info.si_signo = signr; 2258 info.si_code = exit_code; 2259 info.si_pid = task_pid_vnr(current); 2260 info.si_uid = from_kuid_munged(current_user_ns(), current_uid()); 2261 2262 /* Let the debugger run. */ 2263 ptrace_stop(exit_code, why, 1, &info); 2264 } 2265 2266 void ptrace_notify(int exit_code) 2267 { 2268 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP); 2269 if (unlikely(current->task_works)) 2270 task_work_run(); 2271 2272 spin_lock_irq(¤t->sighand->siglock); 2273 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED); 2274 spin_unlock_irq(¤t->sighand->siglock); 2275 } 2276 2277 /** 2278 * do_signal_stop - handle group stop for SIGSTOP and other stop signals 2279 * @signr: signr causing group stop if initiating 2280 * 2281 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr 2282 * and participate in it. If already set, participate in the existing 2283 * group stop. If participated in a group stop (and thus slept), %true is 2284 * returned with siglock released. 2285 * 2286 * If ptraced, this function doesn't handle stop itself. Instead, 2287 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock 2288 * untouched. The caller must ensure that INTERRUPT trap handling takes 2289 * places afterwards. 2290 * 2291 * CONTEXT: 2292 * Must be called with @current->sighand->siglock held, which is released 2293 * on %true return. 2294 * 2295 * RETURNS: 2296 * %false if group stop is already cancelled or ptrace trap is scheduled. 2297 * %true if participated in group stop. 2298 */ 2299 static bool do_signal_stop(int signr) 2300 __releases(¤t->sighand->siglock) 2301 { 2302 struct signal_struct *sig = current->signal; 2303 2304 if (!(current->jobctl & JOBCTL_STOP_PENDING)) { 2305 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME; 2306 struct task_struct *t; 2307 2308 /* signr will be recorded in task->jobctl for retries */ 2309 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK); 2310 2311 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) || 2312 unlikely(signal_group_exit(sig))) 2313 return false; 2314 /* 2315 * There is no group stop already in progress. We must 2316 * initiate one now. 2317 * 2318 * While ptraced, a task may be resumed while group stop is 2319 * still in effect and then receive a stop signal and 2320 * initiate another group stop. This deviates from the 2321 * usual behavior as two consecutive stop signals can't 2322 * cause two group stops when !ptraced. That is why we 2323 * also check !task_is_stopped(t) below. 2324 * 2325 * The condition can be distinguished by testing whether 2326 * SIGNAL_STOP_STOPPED is already set. Don't generate 2327 * group_exit_code in such case. 2328 * 2329 * This is not necessary for SIGNAL_STOP_CONTINUED because 2330 * an intervening stop signal is required to cause two 2331 * continued events regardless of ptrace. 2332 */ 2333 if (!(sig->flags & SIGNAL_STOP_STOPPED)) 2334 sig->group_exit_code = signr; 2335 2336 sig->group_stop_count = 0; 2337 2338 if (task_set_jobctl_pending(current, signr | gstop)) 2339 sig->group_stop_count++; 2340 2341 t = current; 2342 while_each_thread(current, t) { 2343 /* 2344 * Setting state to TASK_STOPPED for a group 2345 * stop is always done with the siglock held, 2346 * so this check has no races. 2347 */ 2348 if (!task_is_stopped(t) && 2349 task_set_jobctl_pending(t, signr | gstop)) { 2350 sig->group_stop_count++; 2351 if (likely(!(t->ptrace & PT_SEIZED))) 2352 signal_wake_up(t, 0); 2353 else 2354 ptrace_trap_notify(t); 2355 } 2356 } 2357 } 2358 2359 if (likely(!current->ptrace)) { 2360 int notify = 0; 2361 2362 /* 2363 * If there are no other threads in the group, or if there 2364 * is a group stop in progress and we are the last to stop, 2365 * report to the parent. 2366 */ 2367 if (task_participate_group_stop(current)) 2368 notify = CLD_STOPPED; 2369 2370 set_special_state(TASK_STOPPED); 2371 spin_unlock_irq(¤t->sighand->siglock); 2372 2373 /* 2374 * Notify the parent of the group stop completion. Because 2375 * we're not holding either the siglock or tasklist_lock 2376 * here, ptracer may attach inbetween; however, this is for 2377 * group stop and should always be delivered to the real 2378 * parent of the group leader. The new ptracer will get 2379 * its notification when this task transitions into 2380 * TASK_TRACED. 2381 */ 2382 if (notify) { 2383 read_lock(&tasklist_lock); 2384 do_notify_parent_cldstop(current, false, notify); 2385 read_unlock(&tasklist_lock); 2386 } 2387 2388 /* Now we don't run again until woken by SIGCONT or SIGKILL */ 2389 cgroup_enter_frozen(); 2390 freezable_schedule(); 2391 return true; 2392 } else { 2393 /* 2394 * While ptraced, group stop is handled by STOP trap. 2395 * Schedule it and let the caller deal with it. 2396 */ 2397 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP); 2398 return false; 2399 } 2400 } 2401 2402 /** 2403 * do_jobctl_trap - take care of ptrace jobctl traps 2404 * 2405 * When PT_SEIZED, it's used for both group stop and explicit 2406 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with 2407 * accompanying siginfo. If stopped, lower eight bits of exit_code contain 2408 * the stop signal; otherwise, %SIGTRAP. 2409 * 2410 * When !PT_SEIZED, it's used only for group stop trap with stop signal 2411 * number as exit_code and no siginfo. 2412 * 2413 * CONTEXT: 2414 * Must be called with @current->sighand->siglock held, which may be 2415 * released and re-acquired before returning with intervening sleep. 2416 */ 2417 static void do_jobctl_trap(void) 2418 { 2419 struct signal_struct *signal = current->signal; 2420 int signr = current->jobctl & JOBCTL_STOP_SIGMASK; 2421 2422 if (current->ptrace & PT_SEIZED) { 2423 if (!signal->group_stop_count && 2424 !(signal->flags & SIGNAL_STOP_STOPPED)) 2425 signr = SIGTRAP; 2426 WARN_ON_ONCE(!signr); 2427 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8), 2428 CLD_STOPPED); 2429 } else { 2430 WARN_ON_ONCE(!signr); 2431 ptrace_stop(signr, CLD_STOPPED, 0, NULL); 2432 current->exit_code = 0; 2433 } 2434 } 2435 2436 /** 2437 * do_freezer_trap - handle the freezer jobctl trap 2438 * 2439 * Puts the task into frozen state, if only the task is not about to quit. 2440 * In this case it drops JOBCTL_TRAP_FREEZE. 2441 * 2442 * CONTEXT: 2443 * Must be called with @current->sighand->siglock held, 2444 * which is always released before returning. 2445 */ 2446 static void do_freezer_trap(void) 2447 __releases(¤t->sighand->siglock) 2448 { 2449 /* 2450 * If there are other trap bits pending except JOBCTL_TRAP_FREEZE, 2451 * let's make another loop to give it a chance to be handled. 2452 * In any case, we'll return back. 2453 */ 2454 if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) != 2455 JOBCTL_TRAP_FREEZE) { 2456 spin_unlock_irq(¤t->sighand->siglock); 2457 return; 2458 } 2459 2460 /* 2461 * Now we're sure that there is no pending fatal signal and no 2462 * pending traps. Clear TIF_SIGPENDING to not get out of schedule() 2463 * immediately (if there is a non-fatal signal pending), and 2464 * put the task into sleep. 2465 */ 2466 __set_current_state(TASK_INTERRUPTIBLE); 2467 clear_thread_flag(TIF_SIGPENDING); 2468 spin_unlock_irq(¤t->sighand->siglock); 2469 cgroup_enter_frozen(); 2470 freezable_schedule(); 2471 } 2472 2473 static int ptrace_signal(int signr, kernel_siginfo_t *info) 2474 { 2475 /* 2476 * We do not check sig_kernel_stop(signr) but set this marker 2477 * unconditionally because we do not know whether debugger will 2478 * change signr. This flag has no meaning unless we are going 2479 * to stop after return from ptrace_stop(). In this case it will 2480 * be checked in do_signal_stop(), we should only stop if it was 2481 * not cleared by SIGCONT while we were sleeping. See also the 2482 * comment in dequeue_signal(). 2483 */ 2484 current->jobctl |= JOBCTL_STOP_DEQUEUED; 2485 ptrace_stop(signr, CLD_TRAPPED, 0, info); 2486 2487 /* We're back. Did the debugger cancel the sig? */ 2488 signr = current->exit_code; 2489 if (signr == 0) 2490 return signr; 2491 2492 current->exit_code = 0; 2493 2494 /* 2495 * Update the siginfo structure if the signal has 2496 * changed. If the debugger wanted something 2497 * specific in the siginfo structure then it should 2498 * have updated *info via PTRACE_SETSIGINFO. 2499 */ 2500 if (signr != info->si_signo) { 2501 clear_siginfo(info); 2502 info->si_signo = signr; 2503 info->si_errno = 0; 2504 info->si_code = SI_USER; 2505 rcu_read_lock(); 2506 info->si_pid = task_pid_vnr(current->parent); 2507 info->si_uid = from_kuid_munged(current_user_ns(), 2508 task_uid(current->parent)); 2509 rcu_read_unlock(); 2510 } 2511 2512 /* If the (new) signal is now blocked, requeue it. */ 2513 if (sigismember(¤t->blocked, signr)) { 2514 send_signal(signr, info, current, PIDTYPE_PID); 2515 signr = 0; 2516 } 2517 2518 return signr; 2519 } 2520 2521 bool get_signal(struct ksignal *ksig) 2522 { 2523 struct sighand_struct *sighand = current->sighand; 2524 struct signal_struct *signal = current->signal; 2525 int signr; 2526 2527 if (unlikely(current->task_works)) 2528 task_work_run(); 2529 2530 if (unlikely(uprobe_deny_signal())) 2531 return false; 2532 2533 /* 2534 * Do this once, we can't return to user-mode if freezing() == T. 2535 * do_signal_stop() and ptrace_stop() do freezable_schedule() and 2536 * thus do not need another check after return. 2537 */ 2538 try_to_freeze(); 2539 2540 relock: 2541 spin_lock_irq(&sighand->siglock); 2542 /* 2543 * Every stopped thread goes here after wakeup. Check to see if 2544 * we should notify the parent, prepare_signal(SIGCONT) encodes 2545 * the CLD_ si_code into SIGNAL_CLD_MASK bits. 2546 */ 2547 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) { 2548 int why; 2549 2550 if (signal->flags & SIGNAL_CLD_CONTINUED) 2551 why = CLD_CONTINUED; 2552 else 2553 why = CLD_STOPPED; 2554 2555 signal->flags &= ~SIGNAL_CLD_MASK; 2556 2557 spin_unlock_irq(&sighand->siglock); 2558 2559 /* 2560 * Notify the parent that we're continuing. This event is 2561 * always per-process and doesn't make whole lot of sense 2562 * for ptracers, who shouldn't consume the state via 2563 * wait(2) either, but, for backward compatibility, notify 2564 * the ptracer of the group leader too unless it's gonna be 2565 * a duplicate. 2566 */ 2567 read_lock(&tasklist_lock); 2568 do_notify_parent_cldstop(current, false, why); 2569 2570 if (ptrace_reparented(current->group_leader)) 2571 do_notify_parent_cldstop(current->group_leader, 2572 true, why); 2573 read_unlock(&tasklist_lock); 2574 2575 goto relock; 2576 } 2577 2578 /* Has this task already been marked for death? */ 2579 if (signal_group_exit(signal)) { 2580 ksig->info.si_signo = signr = SIGKILL; 2581 sigdelset(¤t->pending.signal, SIGKILL); 2582 trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO, 2583 &sighand->action[SIGKILL - 1]); 2584 recalc_sigpending(); 2585 goto fatal; 2586 } 2587 2588 for (;;) { 2589 struct k_sigaction *ka; 2590 2591 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) && 2592 do_signal_stop(0)) 2593 goto relock; 2594 2595 if (unlikely(current->jobctl & 2596 (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) { 2597 if (current->jobctl & JOBCTL_TRAP_MASK) { 2598 do_jobctl_trap(); 2599 spin_unlock_irq(&sighand->siglock); 2600 } else if (current->jobctl & JOBCTL_TRAP_FREEZE) 2601 do_freezer_trap(); 2602 2603 goto relock; 2604 } 2605 2606 /* 2607 * If the task is leaving the frozen state, let's update 2608 * cgroup counters and reset the frozen bit. 2609 */ 2610 if (unlikely(cgroup_task_frozen(current))) { 2611 spin_unlock_irq(&sighand->siglock); 2612 cgroup_leave_frozen(false); 2613 goto relock; 2614 } 2615 2616 /* 2617 * Signals generated by the execution of an instruction 2618 * need to be delivered before any other pending signals 2619 * so that the instruction pointer in the signal stack 2620 * frame points to the faulting instruction. 2621 */ 2622 signr = dequeue_synchronous_signal(&ksig->info); 2623 if (!signr) 2624 signr = dequeue_signal(current, ¤t->blocked, &ksig->info); 2625 2626 if (!signr) 2627 break; /* will return 0 */ 2628 2629 if (unlikely(current->ptrace) && signr != SIGKILL) { 2630 signr = ptrace_signal(signr, &ksig->info); 2631 if (!signr) 2632 continue; 2633 } 2634 2635 ka = &sighand->action[signr-1]; 2636 2637 /* Trace actually delivered signals. */ 2638 trace_signal_deliver(signr, &ksig->info, ka); 2639 2640 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */ 2641 continue; 2642 if (ka->sa.sa_handler != SIG_DFL) { 2643 /* Run the handler. */ 2644 ksig->ka = *ka; 2645 2646 if (ka->sa.sa_flags & SA_ONESHOT) 2647 ka->sa.sa_handler = SIG_DFL; 2648 2649 break; /* will return non-zero "signr" value */ 2650 } 2651 2652 /* 2653 * Now we are doing the default action for this signal. 2654 */ 2655 if (sig_kernel_ignore(signr)) /* Default is nothing. */ 2656 continue; 2657 2658 /* 2659 * Global init gets no signals it doesn't want. 2660 * Container-init gets no signals it doesn't want from same 2661 * container. 2662 * 2663 * Note that if global/container-init sees a sig_kernel_only() 2664 * signal here, the signal must have been generated internally 2665 * or must have come from an ancestor namespace. In either 2666 * case, the signal cannot be dropped. 2667 */ 2668 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) && 2669 !sig_kernel_only(signr)) 2670 continue; 2671 2672 if (sig_kernel_stop(signr)) { 2673 /* 2674 * The default action is to stop all threads in 2675 * the thread group. The job control signals 2676 * do nothing in an orphaned pgrp, but SIGSTOP 2677 * always works. Note that siglock needs to be 2678 * dropped during the call to is_orphaned_pgrp() 2679 * because of lock ordering with tasklist_lock. 2680 * This allows an intervening SIGCONT to be posted. 2681 * We need to check for that and bail out if necessary. 2682 */ 2683 if (signr != SIGSTOP) { 2684 spin_unlock_irq(&sighand->siglock); 2685 2686 /* signals can be posted during this window */ 2687 2688 if (is_current_pgrp_orphaned()) 2689 goto relock; 2690 2691 spin_lock_irq(&sighand->siglock); 2692 } 2693 2694 if (likely(do_signal_stop(ksig->info.si_signo))) { 2695 /* It released the siglock. */ 2696 goto relock; 2697 } 2698 2699 /* 2700 * We didn't actually stop, due to a race 2701 * with SIGCONT or something like that. 2702 */ 2703 continue; 2704 } 2705 2706 fatal: 2707 spin_unlock_irq(&sighand->siglock); 2708 if (unlikely(cgroup_task_frozen(current))) 2709 cgroup_leave_frozen(true); 2710 2711 /* 2712 * Anything else is fatal, maybe with a core dump. 2713 */ 2714 current->flags |= PF_SIGNALED; 2715 2716 if (sig_kernel_coredump(signr)) { 2717 if (print_fatal_signals) 2718 print_fatal_signal(ksig->info.si_signo); 2719 proc_coredump_connector(current); 2720 /* 2721 * If it was able to dump core, this kills all 2722 * other threads in the group and synchronizes with 2723 * their demise. If we lost the race with another 2724 * thread getting here, it set group_exit_code 2725 * first and our do_group_exit call below will use 2726 * that value and ignore the one we pass it. 2727 */ 2728 do_coredump(&ksig->info); 2729 } 2730 2731 /* 2732 * Death signals, no core dump. 2733 */ 2734 do_group_exit(ksig->info.si_signo); 2735 /* NOTREACHED */ 2736 } 2737 spin_unlock_irq(&sighand->siglock); 2738 2739 ksig->sig = signr; 2740 return ksig->sig > 0; 2741 } 2742 2743 /** 2744 * signal_delivered - 2745 * @ksig: kernel signal struct 2746 * @stepping: nonzero if debugger single-step or block-step in use 2747 * 2748 * This function should be called when a signal has successfully been 2749 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask 2750 * is always blocked, and the signal itself is blocked unless %SA_NODEFER 2751 * is set in @ksig->ka.sa.sa_flags. Tracing is notified. 2752 */ 2753 static void signal_delivered(struct ksignal *ksig, int stepping) 2754 { 2755 sigset_t blocked; 2756 2757 /* A signal was successfully delivered, and the 2758 saved sigmask was stored on the signal frame, 2759 and will be restored by sigreturn. So we can 2760 simply clear the restore sigmask flag. */ 2761 clear_restore_sigmask(); 2762 2763 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask); 2764 if (!(ksig->ka.sa.sa_flags & SA_NODEFER)) 2765 sigaddset(&blocked, ksig->sig); 2766 set_current_blocked(&blocked); 2767 tracehook_signal_handler(stepping); 2768 } 2769 2770 void signal_setup_done(int failed, struct ksignal *ksig, int stepping) 2771 { 2772 if (failed) 2773 force_sigsegv(ksig->sig); 2774 else 2775 signal_delivered(ksig, stepping); 2776 } 2777 2778 /* 2779 * It could be that complete_signal() picked us to notify about the 2780 * group-wide signal. Other threads should be notified now to take 2781 * the shared signals in @which since we will not. 2782 */ 2783 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which) 2784 { 2785 sigset_t retarget; 2786 struct task_struct *t; 2787 2788 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which); 2789 if (sigisemptyset(&retarget)) 2790 return; 2791 2792 t = tsk; 2793 while_each_thread(tsk, t) { 2794 if (t->flags & PF_EXITING) 2795 continue; 2796 2797 if (!has_pending_signals(&retarget, &t->blocked)) 2798 continue; 2799 /* Remove the signals this thread can handle. */ 2800 sigandsets(&retarget, &retarget, &t->blocked); 2801 2802 if (!signal_pending(t)) 2803 signal_wake_up(t, 0); 2804 2805 if (sigisemptyset(&retarget)) 2806 break; 2807 } 2808 } 2809 2810 void exit_signals(struct task_struct *tsk) 2811 { 2812 int group_stop = 0; 2813 sigset_t unblocked; 2814 2815 /* 2816 * @tsk is about to have PF_EXITING set - lock out users which 2817 * expect stable threadgroup. 2818 */ 2819 cgroup_threadgroup_change_begin(tsk); 2820 2821 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) { 2822 tsk->flags |= PF_EXITING; 2823 cgroup_threadgroup_change_end(tsk); 2824 return; 2825 } 2826 2827 spin_lock_irq(&tsk->sighand->siglock); 2828 /* 2829 * From now this task is not visible for group-wide signals, 2830 * see wants_signal(), do_signal_stop(). 2831 */ 2832 tsk->flags |= PF_EXITING; 2833 2834 cgroup_threadgroup_change_end(tsk); 2835 2836 if (!signal_pending(tsk)) 2837 goto out; 2838 2839 unblocked = tsk->blocked; 2840 signotset(&unblocked); 2841 retarget_shared_pending(tsk, &unblocked); 2842 2843 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) && 2844 task_participate_group_stop(tsk)) 2845 group_stop = CLD_STOPPED; 2846 out: 2847 spin_unlock_irq(&tsk->sighand->siglock); 2848 2849 /* 2850 * If group stop has completed, deliver the notification. This 2851 * should always go to the real parent of the group leader. 2852 */ 2853 if (unlikely(group_stop)) { 2854 read_lock(&tasklist_lock); 2855 do_notify_parent_cldstop(tsk, false, group_stop); 2856 read_unlock(&tasklist_lock); 2857 } 2858 } 2859 2860 /* 2861 * System call entry points. 2862 */ 2863 2864 /** 2865 * sys_restart_syscall - restart a system call 2866 */ 2867 SYSCALL_DEFINE0(restart_syscall) 2868 { 2869 struct restart_block *restart = ¤t->restart_block; 2870 return restart->fn(restart); 2871 } 2872 2873 long do_no_restart_syscall(struct restart_block *param) 2874 { 2875 return -EINTR; 2876 } 2877 2878 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset) 2879 { 2880 if (signal_pending(tsk) && !thread_group_empty(tsk)) { 2881 sigset_t newblocked; 2882 /* A set of now blocked but previously unblocked signals. */ 2883 sigandnsets(&newblocked, newset, ¤t->blocked); 2884 retarget_shared_pending(tsk, &newblocked); 2885 } 2886 tsk->blocked = *newset; 2887 recalc_sigpending(); 2888 } 2889 2890 /** 2891 * set_current_blocked - change current->blocked mask 2892 * @newset: new mask 2893 * 2894 * It is wrong to change ->blocked directly, this helper should be used 2895 * to ensure the process can't miss a shared signal we are going to block. 2896 */ 2897 void set_current_blocked(sigset_t *newset) 2898 { 2899 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP)); 2900 __set_current_blocked(newset); 2901 } 2902 2903 void __set_current_blocked(const sigset_t *newset) 2904 { 2905 struct task_struct *tsk = current; 2906 2907 /* 2908 * In case the signal mask hasn't changed, there is nothing we need 2909 * to do. The current->blocked shouldn't be modified by other task. 2910 */ 2911 if (sigequalsets(&tsk->blocked, newset)) 2912 return; 2913 2914 spin_lock_irq(&tsk->sighand->siglock); 2915 __set_task_blocked(tsk, newset); 2916 spin_unlock_irq(&tsk->sighand->siglock); 2917 } 2918 2919 /* 2920 * This is also useful for kernel threads that want to temporarily 2921 * (or permanently) block certain signals. 2922 * 2923 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel 2924 * interface happily blocks "unblockable" signals like SIGKILL 2925 * and friends. 2926 */ 2927 int sigprocmask(int how, sigset_t *set, sigset_t *oldset) 2928 { 2929 struct task_struct *tsk = current; 2930 sigset_t newset; 2931 2932 /* Lockless, only current can change ->blocked, never from irq */ 2933 if (oldset) 2934 *oldset = tsk->blocked; 2935 2936 switch (how) { 2937 case SIG_BLOCK: 2938 sigorsets(&newset, &tsk->blocked, set); 2939 break; 2940 case SIG_UNBLOCK: 2941 sigandnsets(&newset, &tsk->blocked, set); 2942 break; 2943 case SIG_SETMASK: 2944 newset = *set; 2945 break; 2946 default: 2947 return -EINVAL; 2948 } 2949 2950 __set_current_blocked(&newset); 2951 return 0; 2952 } 2953 EXPORT_SYMBOL(sigprocmask); 2954 2955 /* 2956 * The api helps set app-provided sigmasks. 2957 * 2958 * This is useful for syscalls such as ppoll, pselect, io_pgetevents and 2959 * epoll_pwait where a new sigmask is passed from userland for the syscalls. 2960 * 2961 * Note that it does set_restore_sigmask() in advance, so it must be always 2962 * paired with restore_saved_sigmask_unless() before return from syscall. 2963 */ 2964 int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize) 2965 { 2966 sigset_t kmask; 2967 2968 if (!umask) 2969 return 0; 2970 if (sigsetsize != sizeof(sigset_t)) 2971 return -EINVAL; 2972 if (copy_from_user(&kmask, umask, sizeof(sigset_t))) 2973 return -EFAULT; 2974 2975 set_restore_sigmask(); 2976 current->saved_sigmask = current->blocked; 2977 set_current_blocked(&kmask); 2978 2979 return 0; 2980 } 2981 2982 #ifdef CONFIG_COMPAT 2983 int set_compat_user_sigmask(const compat_sigset_t __user *umask, 2984 size_t sigsetsize) 2985 { 2986 sigset_t kmask; 2987 2988 if (!umask) 2989 return 0; 2990 if (sigsetsize != sizeof(compat_sigset_t)) 2991 return -EINVAL; 2992 if (get_compat_sigset(&kmask, umask)) 2993 return -EFAULT; 2994 2995 set_restore_sigmask(); 2996 current->saved_sigmask = current->blocked; 2997 set_current_blocked(&kmask); 2998 2999 return 0; 3000 } 3001 #endif 3002 3003 /** 3004 * sys_rt_sigprocmask - change the list of currently blocked signals 3005 * @how: whether to add, remove, or set signals 3006 * @nset: stores pending signals 3007 * @oset: previous value of signal mask if non-null 3008 * @sigsetsize: size of sigset_t type 3009 */ 3010 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset, 3011 sigset_t __user *, oset, size_t, sigsetsize) 3012 { 3013 sigset_t old_set, new_set; 3014 int error; 3015 3016 /* XXX: Don't preclude handling different sized sigset_t's. */ 3017 if (sigsetsize != sizeof(sigset_t)) 3018 return -EINVAL; 3019 3020 old_set = current->blocked; 3021 3022 if (nset) { 3023 if (copy_from_user(&new_set, nset, sizeof(sigset_t))) 3024 return -EFAULT; 3025 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); 3026 3027 error = sigprocmask(how, &new_set, NULL); 3028 if (error) 3029 return error; 3030 } 3031 3032 if (oset) { 3033 if (copy_to_user(oset, &old_set, sizeof(sigset_t))) 3034 return -EFAULT; 3035 } 3036 3037 return 0; 3038 } 3039 3040 #ifdef CONFIG_COMPAT 3041 COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset, 3042 compat_sigset_t __user *, oset, compat_size_t, sigsetsize) 3043 { 3044 sigset_t old_set = current->blocked; 3045 3046 /* XXX: Don't preclude handling different sized sigset_t's. */ 3047 if (sigsetsize != sizeof(sigset_t)) 3048 return -EINVAL; 3049 3050 if (nset) { 3051 sigset_t new_set; 3052 int error; 3053 if (get_compat_sigset(&new_set, nset)) 3054 return -EFAULT; 3055 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); 3056 3057 error = sigprocmask(how, &new_set, NULL); 3058 if (error) 3059 return error; 3060 } 3061 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0; 3062 } 3063 #endif 3064 3065 static void do_sigpending(sigset_t *set) 3066 { 3067 spin_lock_irq(¤t->sighand->siglock); 3068 sigorsets(set, ¤t->pending.signal, 3069 ¤t->signal->shared_pending.signal); 3070 spin_unlock_irq(¤t->sighand->siglock); 3071 3072 /* Outside the lock because only this thread touches it. */ 3073 sigandsets(set, ¤t->blocked, set); 3074 } 3075 3076 /** 3077 * sys_rt_sigpending - examine a pending signal that has been raised 3078 * while blocked 3079 * @uset: stores pending signals 3080 * @sigsetsize: size of sigset_t type or larger 3081 */ 3082 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize) 3083 { 3084 sigset_t set; 3085 3086 if (sigsetsize > sizeof(*uset)) 3087 return -EINVAL; 3088 3089 do_sigpending(&set); 3090 3091 if (copy_to_user(uset, &set, sigsetsize)) 3092 return -EFAULT; 3093 3094 return 0; 3095 } 3096 3097 #ifdef CONFIG_COMPAT 3098 COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset, 3099 compat_size_t, sigsetsize) 3100 { 3101 sigset_t set; 3102 3103 if (sigsetsize > sizeof(*uset)) 3104 return -EINVAL; 3105 3106 do_sigpending(&set); 3107 3108 return put_compat_sigset(uset, &set, sigsetsize); 3109 } 3110 #endif 3111 3112 static const struct { 3113 unsigned char limit, layout; 3114 } sig_sicodes[] = { 3115 [SIGILL] = { NSIGILL, SIL_FAULT }, 3116 [SIGFPE] = { NSIGFPE, SIL_FAULT }, 3117 [SIGSEGV] = { NSIGSEGV, SIL_FAULT }, 3118 [SIGBUS] = { NSIGBUS, SIL_FAULT }, 3119 [SIGTRAP] = { NSIGTRAP, SIL_FAULT }, 3120 #if defined(SIGEMT) 3121 [SIGEMT] = { NSIGEMT, SIL_FAULT }, 3122 #endif 3123 [SIGCHLD] = { NSIGCHLD, SIL_CHLD }, 3124 [SIGPOLL] = { NSIGPOLL, SIL_POLL }, 3125 [SIGSYS] = { NSIGSYS, SIL_SYS }, 3126 }; 3127 3128 static bool known_siginfo_layout(unsigned sig, int si_code) 3129 { 3130 if (si_code == SI_KERNEL) 3131 return true; 3132 else if ((si_code > SI_USER)) { 3133 if (sig_specific_sicodes(sig)) { 3134 if (si_code <= sig_sicodes[sig].limit) 3135 return true; 3136 } 3137 else if (si_code <= NSIGPOLL) 3138 return true; 3139 } 3140 else if (si_code >= SI_DETHREAD) 3141 return true; 3142 else if (si_code == SI_ASYNCNL) 3143 return true; 3144 return false; 3145 } 3146 3147 enum siginfo_layout siginfo_layout(unsigned sig, int si_code) 3148 { 3149 enum siginfo_layout layout = SIL_KILL; 3150 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) { 3151 if ((sig < ARRAY_SIZE(sig_sicodes)) && 3152 (si_code <= sig_sicodes[sig].limit)) { 3153 layout = sig_sicodes[sig].layout; 3154 /* Handle the exceptions */ 3155 if ((sig == SIGBUS) && 3156 (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO)) 3157 layout = SIL_FAULT_MCEERR; 3158 else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR)) 3159 layout = SIL_FAULT_BNDERR; 3160 #ifdef SEGV_PKUERR 3161 else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR)) 3162 layout = SIL_FAULT_PKUERR; 3163 #endif 3164 } 3165 else if (si_code <= NSIGPOLL) 3166 layout = SIL_POLL; 3167 } else { 3168 if (si_code == SI_TIMER) 3169 layout = SIL_TIMER; 3170 else if (si_code == SI_SIGIO) 3171 layout = SIL_POLL; 3172 else if (si_code < 0) 3173 layout = SIL_RT; 3174 } 3175 return layout; 3176 } 3177 3178 static inline char __user *si_expansion(const siginfo_t __user *info) 3179 { 3180 return ((char __user *)info) + sizeof(struct kernel_siginfo); 3181 } 3182 3183 int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from) 3184 { 3185 char __user *expansion = si_expansion(to); 3186 if (copy_to_user(to, from , sizeof(struct kernel_siginfo))) 3187 return -EFAULT; 3188 if (clear_user(expansion, SI_EXPANSION_SIZE)) 3189 return -EFAULT; 3190 return 0; 3191 } 3192 3193 static int post_copy_siginfo_from_user(kernel_siginfo_t *info, 3194 const siginfo_t __user *from) 3195 { 3196 if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) { 3197 char __user *expansion = si_expansion(from); 3198 char buf[SI_EXPANSION_SIZE]; 3199 int i; 3200 /* 3201 * An unknown si_code might need more than 3202 * sizeof(struct kernel_siginfo) bytes. Verify all of the 3203 * extra bytes are 0. This guarantees copy_siginfo_to_user 3204 * will return this data to userspace exactly. 3205 */ 3206 if (copy_from_user(&buf, expansion, SI_EXPANSION_SIZE)) 3207 return -EFAULT; 3208 for (i = 0; i < SI_EXPANSION_SIZE; i++) { 3209 if (buf[i] != 0) 3210 return -E2BIG; 3211 } 3212 } 3213 return 0; 3214 } 3215 3216 static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to, 3217 const siginfo_t __user *from) 3218 { 3219 if (copy_from_user(to, from, sizeof(struct kernel_siginfo))) 3220 return -EFAULT; 3221 to->si_signo = signo; 3222 return post_copy_siginfo_from_user(to, from); 3223 } 3224 3225 int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from) 3226 { 3227 if (copy_from_user(to, from, sizeof(struct kernel_siginfo))) 3228 return -EFAULT; 3229 return post_copy_siginfo_from_user(to, from); 3230 } 3231 3232 #ifdef CONFIG_COMPAT 3233 int copy_siginfo_to_user32(struct compat_siginfo __user *to, 3234 const struct kernel_siginfo *from) 3235 #if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION) 3236 { 3237 return __copy_siginfo_to_user32(to, from, in_x32_syscall()); 3238 } 3239 int __copy_siginfo_to_user32(struct compat_siginfo __user *to, 3240 const struct kernel_siginfo *from, bool x32_ABI) 3241 #endif 3242 { 3243 struct compat_siginfo new; 3244 memset(&new, 0, sizeof(new)); 3245 3246 new.si_signo = from->si_signo; 3247 new.si_errno = from->si_errno; 3248 new.si_code = from->si_code; 3249 switch(siginfo_layout(from->si_signo, from->si_code)) { 3250 case SIL_KILL: 3251 new.si_pid = from->si_pid; 3252 new.si_uid = from->si_uid; 3253 break; 3254 case SIL_TIMER: 3255 new.si_tid = from->si_tid; 3256 new.si_overrun = from->si_overrun; 3257 new.si_int = from->si_int; 3258 break; 3259 case SIL_POLL: 3260 new.si_band = from->si_band; 3261 new.si_fd = from->si_fd; 3262 break; 3263 case SIL_FAULT: 3264 new.si_addr = ptr_to_compat(from->si_addr); 3265 #ifdef __ARCH_SI_TRAPNO 3266 new.si_trapno = from->si_trapno; 3267 #endif 3268 break; 3269 case SIL_FAULT_MCEERR: 3270 new.si_addr = ptr_to_compat(from->si_addr); 3271 #ifdef __ARCH_SI_TRAPNO 3272 new.si_trapno = from->si_trapno; 3273 #endif 3274 new.si_addr_lsb = from->si_addr_lsb; 3275 break; 3276 case SIL_FAULT_BNDERR: 3277 new.si_addr = ptr_to_compat(from->si_addr); 3278 #ifdef __ARCH_SI_TRAPNO 3279 new.si_trapno = from->si_trapno; 3280 #endif 3281 new.si_lower = ptr_to_compat(from->si_lower); 3282 new.si_upper = ptr_to_compat(from->si_upper); 3283 break; 3284 case SIL_FAULT_PKUERR: 3285 new.si_addr = ptr_to_compat(from->si_addr); 3286 #ifdef __ARCH_SI_TRAPNO 3287 new.si_trapno = from->si_trapno; 3288 #endif 3289 new.si_pkey = from->si_pkey; 3290 break; 3291 case SIL_CHLD: 3292 new.si_pid = from->si_pid; 3293 new.si_uid = from->si_uid; 3294 new.si_status = from->si_status; 3295 #ifdef CONFIG_X86_X32_ABI 3296 if (x32_ABI) { 3297 new._sifields._sigchld_x32._utime = from->si_utime; 3298 new._sifields._sigchld_x32._stime = from->si_stime; 3299 } else 3300 #endif 3301 { 3302 new.si_utime = from->si_utime; 3303 new.si_stime = from->si_stime; 3304 } 3305 break; 3306 case SIL_RT: 3307 new.si_pid = from->si_pid; 3308 new.si_uid = from->si_uid; 3309 new.si_int = from->si_int; 3310 break; 3311 case SIL_SYS: 3312 new.si_call_addr = ptr_to_compat(from->si_call_addr); 3313 new.si_syscall = from->si_syscall; 3314 new.si_arch = from->si_arch; 3315 break; 3316 } 3317 3318 if (copy_to_user(to, &new, sizeof(struct compat_siginfo))) 3319 return -EFAULT; 3320 3321 return 0; 3322 } 3323 3324 static int post_copy_siginfo_from_user32(kernel_siginfo_t *to, 3325 const struct compat_siginfo *from) 3326 { 3327 clear_siginfo(to); 3328 to->si_signo = from->si_signo; 3329 to->si_errno = from->si_errno; 3330 to->si_code = from->si_code; 3331 switch(siginfo_layout(from->si_signo, from->si_code)) { 3332 case SIL_KILL: 3333 to->si_pid = from->si_pid; 3334 to->si_uid = from->si_uid; 3335 break; 3336 case SIL_TIMER: 3337 to->si_tid = from->si_tid; 3338 to->si_overrun = from->si_overrun; 3339 to->si_int = from->si_int; 3340 break; 3341 case SIL_POLL: 3342 to->si_band = from->si_band; 3343 to->si_fd = from->si_fd; 3344 break; 3345 case SIL_FAULT: 3346 to->si_addr = compat_ptr(from->si_addr); 3347 #ifdef __ARCH_SI_TRAPNO 3348 to->si_trapno = from->si_trapno; 3349 #endif 3350 break; 3351 case SIL_FAULT_MCEERR: 3352 to->si_addr = compat_ptr(from->si_addr); 3353 #ifdef __ARCH_SI_TRAPNO 3354 to->si_trapno = from->si_trapno; 3355 #endif 3356 to->si_addr_lsb = from->si_addr_lsb; 3357 break; 3358 case SIL_FAULT_BNDERR: 3359 to->si_addr = compat_ptr(from->si_addr); 3360 #ifdef __ARCH_SI_TRAPNO 3361 to->si_trapno = from->si_trapno; 3362 #endif 3363 to->si_lower = compat_ptr(from->si_lower); 3364 to->si_upper = compat_ptr(from->si_upper); 3365 break; 3366 case SIL_FAULT_PKUERR: 3367 to->si_addr = compat_ptr(from->si_addr); 3368 #ifdef __ARCH_SI_TRAPNO 3369 to->si_trapno = from->si_trapno; 3370 #endif 3371 to->si_pkey = from->si_pkey; 3372 break; 3373 case SIL_CHLD: 3374 to->si_pid = from->si_pid; 3375 to->si_uid = from->si_uid; 3376 to->si_status = from->si_status; 3377 #ifdef CONFIG_X86_X32_ABI 3378 if (in_x32_syscall()) { 3379 to->si_utime = from->_sifields._sigchld_x32._utime; 3380 to->si_stime = from->_sifields._sigchld_x32._stime; 3381 } else 3382 #endif 3383 { 3384 to->si_utime = from->si_utime; 3385 to->si_stime = from->si_stime; 3386 } 3387 break; 3388 case SIL_RT: 3389 to->si_pid = from->si_pid; 3390 to->si_uid = from->si_uid; 3391 to->si_int = from->si_int; 3392 break; 3393 case SIL_SYS: 3394 to->si_call_addr = compat_ptr(from->si_call_addr); 3395 to->si_syscall = from->si_syscall; 3396 to->si_arch = from->si_arch; 3397 break; 3398 } 3399 return 0; 3400 } 3401 3402 static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to, 3403 const struct compat_siginfo __user *ufrom) 3404 { 3405 struct compat_siginfo from; 3406 3407 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo))) 3408 return -EFAULT; 3409 3410 from.si_signo = signo; 3411 return post_copy_siginfo_from_user32(to, &from); 3412 } 3413 3414 int copy_siginfo_from_user32(struct kernel_siginfo *to, 3415 const struct compat_siginfo __user *ufrom) 3416 { 3417 struct compat_siginfo from; 3418 3419 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo))) 3420 return -EFAULT; 3421 3422 return post_copy_siginfo_from_user32(to, &from); 3423 } 3424 #endif /* CONFIG_COMPAT */ 3425 3426 /** 3427 * do_sigtimedwait - wait for queued signals specified in @which 3428 * @which: queued signals to wait for 3429 * @info: if non-null, the signal's siginfo is returned here 3430 * @ts: upper bound on process time suspension 3431 */ 3432 static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info, 3433 const struct timespec64 *ts) 3434 { 3435 ktime_t *to = NULL, timeout = KTIME_MAX; 3436 struct task_struct *tsk = current; 3437 sigset_t mask = *which; 3438 int sig, ret = 0; 3439 3440 if (ts) { 3441 if (!timespec64_valid(ts)) 3442 return -EINVAL; 3443 timeout = timespec64_to_ktime(*ts); 3444 to = &timeout; 3445 } 3446 3447 /* 3448 * Invert the set of allowed signals to get those we want to block. 3449 */ 3450 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP)); 3451 signotset(&mask); 3452 3453 spin_lock_irq(&tsk->sighand->siglock); 3454 sig = dequeue_signal(tsk, &mask, info); 3455 if (!sig && timeout) { 3456 /* 3457 * None ready, temporarily unblock those we're interested 3458 * while we are sleeping in so that we'll be awakened when 3459 * they arrive. Unblocking is always fine, we can avoid 3460 * set_current_blocked(). 3461 */ 3462 tsk->real_blocked = tsk->blocked; 3463 sigandsets(&tsk->blocked, &tsk->blocked, &mask); 3464 recalc_sigpending(); 3465 spin_unlock_irq(&tsk->sighand->siglock); 3466 3467 __set_current_state(TASK_INTERRUPTIBLE); 3468 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns, 3469 HRTIMER_MODE_REL); 3470 spin_lock_irq(&tsk->sighand->siglock); 3471 __set_task_blocked(tsk, &tsk->real_blocked); 3472 sigemptyset(&tsk->real_blocked); 3473 sig = dequeue_signal(tsk, &mask, info); 3474 } 3475 spin_unlock_irq(&tsk->sighand->siglock); 3476 3477 if (sig) 3478 return sig; 3479 return ret ? -EINTR : -EAGAIN; 3480 } 3481 3482 /** 3483 * sys_rt_sigtimedwait - synchronously wait for queued signals specified 3484 * in @uthese 3485 * @uthese: queued signals to wait for 3486 * @uinfo: if non-null, the signal's siginfo is returned here 3487 * @uts: upper bound on process time suspension 3488 * @sigsetsize: size of sigset_t type 3489 */ 3490 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese, 3491 siginfo_t __user *, uinfo, 3492 const struct __kernel_timespec __user *, uts, 3493 size_t, sigsetsize) 3494 { 3495 sigset_t these; 3496 struct timespec64 ts; 3497 kernel_siginfo_t info; 3498 int ret; 3499 3500 /* XXX: Don't preclude handling different sized sigset_t's. */ 3501 if (sigsetsize != sizeof(sigset_t)) 3502 return -EINVAL; 3503 3504 if (copy_from_user(&these, uthese, sizeof(these))) 3505 return -EFAULT; 3506 3507 if (uts) { 3508 if (get_timespec64(&ts, uts)) 3509 return -EFAULT; 3510 } 3511 3512 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL); 3513 3514 if (ret > 0 && uinfo) { 3515 if (copy_siginfo_to_user(uinfo, &info)) 3516 ret = -EFAULT; 3517 } 3518 3519 return ret; 3520 } 3521 3522 #ifdef CONFIG_COMPAT_32BIT_TIME 3523 SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese, 3524 siginfo_t __user *, uinfo, 3525 const struct old_timespec32 __user *, uts, 3526 size_t, sigsetsize) 3527 { 3528 sigset_t these; 3529 struct timespec64 ts; 3530 kernel_siginfo_t info; 3531 int ret; 3532 3533 if (sigsetsize != sizeof(sigset_t)) 3534 return -EINVAL; 3535 3536 if (copy_from_user(&these, uthese, sizeof(these))) 3537 return -EFAULT; 3538 3539 if (uts) { 3540 if (get_old_timespec32(&ts, uts)) 3541 return -EFAULT; 3542 } 3543 3544 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL); 3545 3546 if (ret > 0 && uinfo) { 3547 if (copy_siginfo_to_user(uinfo, &info)) 3548 ret = -EFAULT; 3549 } 3550 3551 return ret; 3552 } 3553 #endif 3554 3555 #ifdef CONFIG_COMPAT 3556 COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese, 3557 struct compat_siginfo __user *, uinfo, 3558 struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize) 3559 { 3560 sigset_t s; 3561 struct timespec64 t; 3562 kernel_siginfo_t info; 3563 long ret; 3564 3565 if (sigsetsize != sizeof(sigset_t)) 3566 return -EINVAL; 3567 3568 if (get_compat_sigset(&s, uthese)) 3569 return -EFAULT; 3570 3571 if (uts) { 3572 if (get_timespec64(&t, uts)) 3573 return -EFAULT; 3574 } 3575 3576 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL); 3577 3578 if (ret > 0 && uinfo) { 3579 if (copy_siginfo_to_user32(uinfo, &info)) 3580 ret = -EFAULT; 3581 } 3582 3583 return ret; 3584 } 3585 3586 #ifdef CONFIG_COMPAT_32BIT_TIME 3587 COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese, 3588 struct compat_siginfo __user *, uinfo, 3589 struct old_timespec32 __user *, uts, compat_size_t, sigsetsize) 3590 { 3591 sigset_t s; 3592 struct timespec64 t; 3593 kernel_siginfo_t info; 3594 long ret; 3595 3596 if (sigsetsize != sizeof(sigset_t)) 3597 return -EINVAL; 3598 3599 if (get_compat_sigset(&s, uthese)) 3600 return -EFAULT; 3601 3602 if (uts) { 3603 if (get_old_timespec32(&t, uts)) 3604 return -EFAULT; 3605 } 3606 3607 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL); 3608 3609 if (ret > 0 && uinfo) { 3610 if (copy_siginfo_to_user32(uinfo, &info)) 3611 ret = -EFAULT; 3612 } 3613 3614 return ret; 3615 } 3616 #endif 3617 #endif 3618 3619 static inline void prepare_kill_siginfo(int sig, struct kernel_siginfo *info) 3620 { 3621 clear_siginfo(info); 3622 info->si_signo = sig; 3623 info->si_errno = 0; 3624 info->si_code = SI_USER; 3625 info->si_pid = task_tgid_vnr(current); 3626 info->si_uid = from_kuid_munged(current_user_ns(), current_uid()); 3627 } 3628 3629 /** 3630 * sys_kill - send a signal to a process 3631 * @pid: the PID of the process 3632 * @sig: signal to be sent 3633 */ 3634 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig) 3635 { 3636 struct kernel_siginfo info; 3637 3638 prepare_kill_siginfo(sig, &info); 3639 3640 return kill_something_info(sig, &info, pid); 3641 } 3642 3643 /* 3644 * Verify that the signaler and signalee either are in the same pid namespace 3645 * or that the signaler's pid namespace is an ancestor of the signalee's pid 3646 * namespace. 3647 */ 3648 static bool access_pidfd_pidns(struct pid *pid) 3649 { 3650 struct pid_namespace *active = task_active_pid_ns(current); 3651 struct pid_namespace *p = ns_of_pid(pid); 3652 3653 for (;;) { 3654 if (!p) 3655 return false; 3656 if (p == active) 3657 break; 3658 p = p->parent; 3659 } 3660 3661 return true; 3662 } 3663 3664 static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo, siginfo_t *info) 3665 { 3666 #ifdef CONFIG_COMPAT 3667 /* 3668 * Avoid hooking up compat syscalls and instead handle necessary 3669 * conversions here. Note, this is a stop-gap measure and should not be 3670 * considered a generic solution. 3671 */ 3672 if (in_compat_syscall()) 3673 return copy_siginfo_from_user32( 3674 kinfo, (struct compat_siginfo __user *)info); 3675 #endif 3676 return copy_siginfo_from_user(kinfo, info); 3677 } 3678 3679 static struct pid *pidfd_to_pid(const struct file *file) 3680 { 3681 if (file->f_op == &pidfd_fops) 3682 return file->private_data; 3683 3684 return tgid_pidfd_to_pid(file); 3685 } 3686 3687 /** 3688 * sys_pidfd_send_signal - Signal a process through a pidfd 3689 * @pidfd: file descriptor of the process 3690 * @sig: signal to send 3691 * @info: signal info 3692 * @flags: future flags 3693 * 3694 * The syscall currently only signals via PIDTYPE_PID which covers 3695 * kill(<positive-pid>, <signal>. It does not signal threads or process 3696 * groups. 3697 * In order to extend the syscall to threads and process groups the @flags 3698 * argument should be used. In essence, the @flags argument will determine 3699 * what is signaled and not the file descriptor itself. Put in other words, 3700 * grouping is a property of the flags argument not a property of the file 3701 * descriptor. 3702 * 3703 * Return: 0 on success, negative errno on failure 3704 */ 3705 SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig, 3706 siginfo_t __user *, info, unsigned int, flags) 3707 { 3708 int ret; 3709 struct fd f; 3710 struct pid *pid; 3711 kernel_siginfo_t kinfo; 3712 3713 /* Enforce flags be set to 0 until we add an extension. */ 3714 if (flags) 3715 return -EINVAL; 3716 3717 f = fdget(pidfd); 3718 if (!f.file) 3719 return -EBADF; 3720 3721 /* Is this a pidfd? */ 3722 pid = pidfd_to_pid(f.file); 3723 if (IS_ERR(pid)) { 3724 ret = PTR_ERR(pid); 3725 goto err; 3726 } 3727 3728 ret = -EINVAL; 3729 if (!access_pidfd_pidns(pid)) 3730 goto err; 3731 3732 if (info) { 3733 ret = copy_siginfo_from_user_any(&kinfo, info); 3734 if (unlikely(ret)) 3735 goto err; 3736 3737 ret = -EINVAL; 3738 if (unlikely(sig != kinfo.si_signo)) 3739 goto err; 3740 3741 /* Only allow sending arbitrary signals to yourself. */ 3742 ret = -EPERM; 3743 if ((task_pid(current) != pid) && 3744 (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL)) 3745 goto err; 3746 } else { 3747 prepare_kill_siginfo(sig, &kinfo); 3748 } 3749 3750 ret = kill_pid_info(sig, &kinfo, pid); 3751 3752 err: 3753 fdput(f); 3754 return ret; 3755 } 3756 3757 static int 3758 do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info) 3759 { 3760 struct task_struct *p; 3761 int error = -ESRCH; 3762 3763 rcu_read_lock(); 3764 p = find_task_by_vpid(pid); 3765 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) { 3766 error = check_kill_permission(sig, info, p); 3767 /* 3768 * The null signal is a permissions and process existence 3769 * probe. No signal is actually delivered. 3770 */ 3771 if (!error && sig) { 3772 error = do_send_sig_info(sig, info, p, PIDTYPE_PID); 3773 /* 3774 * If lock_task_sighand() failed we pretend the task 3775 * dies after receiving the signal. The window is tiny, 3776 * and the signal is private anyway. 3777 */ 3778 if (unlikely(error == -ESRCH)) 3779 error = 0; 3780 } 3781 } 3782 rcu_read_unlock(); 3783 3784 return error; 3785 } 3786 3787 static int do_tkill(pid_t tgid, pid_t pid, int sig) 3788 { 3789 struct kernel_siginfo info; 3790 3791 clear_siginfo(&info); 3792 info.si_signo = sig; 3793 info.si_errno = 0; 3794 info.si_code = SI_TKILL; 3795 info.si_pid = task_tgid_vnr(current); 3796 info.si_uid = from_kuid_munged(current_user_ns(), current_uid()); 3797 3798 return do_send_specific(tgid, pid, sig, &info); 3799 } 3800 3801 /** 3802 * sys_tgkill - send signal to one specific thread 3803 * @tgid: the thread group ID of the thread 3804 * @pid: the PID of the thread 3805 * @sig: signal to be sent 3806 * 3807 * This syscall also checks the @tgid and returns -ESRCH even if the PID 3808 * exists but it's not belonging to the target process anymore. This 3809 * method solves the problem of threads exiting and PIDs getting reused. 3810 */ 3811 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig) 3812 { 3813 /* This is only valid for single tasks */ 3814 if (pid <= 0 || tgid <= 0) 3815 return -EINVAL; 3816 3817 return do_tkill(tgid, pid, sig); 3818 } 3819 3820 /** 3821 * sys_tkill - send signal to one specific task 3822 * @pid: the PID of the task 3823 * @sig: signal to be sent 3824 * 3825 * Send a signal to only one task, even if it's a CLONE_THREAD task. 3826 */ 3827 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig) 3828 { 3829 /* This is only valid for single tasks */ 3830 if (pid <= 0) 3831 return -EINVAL; 3832 3833 return do_tkill(0, pid, sig); 3834 } 3835 3836 static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info) 3837 { 3838 /* Not even root can pretend to send signals from the kernel. 3839 * Nor can they impersonate a kill()/tgkill(), which adds source info. 3840 */ 3841 if ((info->si_code >= 0 || info->si_code == SI_TKILL) && 3842 (task_pid_vnr(current) != pid)) 3843 return -EPERM; 3844 3845 /* POSIX.1b doesn't mention process groups. */ 3846 return kill_proc_info(sig, info, pid); 3847 } 3848 3849 /** 3850 * sys_rt_sigqueueinfo - send signal information to a signal 3851 * @pid: the PID of the thread 3852 * @sig: signal to be sent 3853 * @uinfo: signal info to be sent 3854 */ 3855 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig, 3856 siginfo_t __user *, uinfo) 3857 { 3858 kernel_siginfo_t info; 3859 int ret = __copy_siginfo_from_user(sig, &info, uinfo); 3860 if (unlikely(ret)) 3861 return ret; 3862 return do_rt_sigqueueinfo(pid, sig, &info); 3863 } 3864 3865 #ifdef CONFIG_COMPAT 3866 COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo, 3867 compat_pid_t, pid, 3868 int, sig, 3869 struct compat_siginfo __user *, uinfo) 3870 { 3871 kernel_siginfo_t info; 3872 int ret = __copy_siginfo_from_user32(sig, &info, uinfo); 3873 if (unlikely(ret)) 3874 return ret; 3875 return do_rt_sigqueueinfo(pid, sig, &info); 3876 } 3877 #endif 3878 3879 static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info) 3880 { 3881 /* This is only valid for single tasks */ 3882 if (pid <= 0 || tgid <= 0) 3883 return -EINVAL; 3884 3885 /* Not even root can pretend to send signals from the kernel. 3886 * Nor can they impersonate a kill()/tgkill(), which adds source info. 3887 */ 3888 if ((info->si_code >= 0 || info->si_code == SI_TKILL) && 3889 (task_pid_vnr(current) != pid)) 3890 return -EPERM; 3891 3892 return do_send_specific(tgid, pid, sig, info); 3893 } 3894 3895 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig, 3896 siginfo_t __user *, uinfo) 3897 { 3898 kernel_siginfo_t info; 3899 int ret = __copy_siginfo_from_user(sig, &info, uinfo); 3900 if (unlikely(ret)) 3901 return ret; 3902 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info); 3903 } 3904 3905 #ifdef CONFIG_COMPAT 3906 COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo, 3907 compat_pid_t, tgid, 3908 compat_pid_t, pid, 3909 int, sig, 3910 struct compat_siginfo __user *, uinfo) 3911 { 3912 kernel_siginfo_t info; 3913 int ret = __copy_siginfo_from_user32(sig, &info, uinfo); 3914 if (unlikely(ret)) 3915 return ret; 3916 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info); 3917 } 3918 #endif 3919 3920 /* 3921 * For kthreads only, must not be used if cloned with CLONE_SIGHAND 3922 */ 3923 void kernel_sigaction(int sig, __sighandler_t action) 3924 { 3925 spin_lock_irq(¤t->sighand->siglock); 3926 current->sighand->action[sig - 1].sa.sa_handler = action; 3927 if (action == SIG_IGN) { 3928 sigset_t mask; 3929 3930 sigemptyset(&mask); 3931 sigaddset(&mask, sig); 3932 3933 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending); 3934 flush_sigqueue_mask(&mask, ¤t->pending); 3935 recalc_sigpending(); 3936 } 3937 spin_unlock_irq(¤t->sighand->siglock); 3938 } 3939 EXPORT_SYMBOL(kernel_sigaction); 3940 3941 void __weak sigaction_compat_abi(struct k_sigaction *act, 3942 struct k_sigaction *oact) 3943 { 3944 } 3945 3946 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) 3947 { 3948 struct task_struct *p = current, *t; 3949 struct k_sigaction *k; 3950 sigset_t mask; 3951 3952 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig))) 3953 return -EINVAL; 3954 3955 k = &p->sighand->action[sig-1]; 3956 3957 spin_lock_irq(&p->sighand->siglock); 3958 if (oact) 3959 *oact = *k; 3960 3961 sigaction_compat_abi(act, oact); 3962 3963 if (act) { 3964 sigdelsetmask(&act->sa.sa_mask, 3965 sigmask(SIGKILL) | sigmask(SIGSTOP)); 3966 *k = *act; 3967 /* 3968 * POSIX 3.3.1.3: 3969 * "Setting a signal action to SIG_IGN for a signal that is 3970 * pending shall cause the pending signal to be discarded, 3971 * whether or not it is blocked." 3972 * 3973 * "Setting a signal action to SIG_DFL for a signal that is 3974 * pending and whose default action is to ignore the signal 3975 * (for example, SIGCHLD), shall cause the pending signal to 3976 * be discarded, whether or not it is blocked" 3977 */ 3978 if (sig_handler_ignored(sig_handler(p, sig), sig)) { 3979 sigemptyset(&mask); 3980 sigaddset(&mask, sig); 3981 flush_sigqueue_mask(&mask, &p->signal->shared_pending); 3982 for_each_thread(p, t) 3983 flush_sigqueue_mask(&mask, &t->pending); 3984 } 3985 } 3986 3987 spin_unlock_irq(&p->sighand->siglock); 3988 return 0; 3989 } 3990 3991 static int 3992 do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp, 3993 size_t min_ss_size) 3994 { 3995 struct task_struct *t = current; 3996 3997 if (oss) { 3998 memset(oss, 0, sizeof(stack_t)); 3999 oss->ss_sp = (void __user *) t->sas_ss_sp; 4000 oss->ss_size = t->sas_ss_size; 4001 oss->ss_flags = sas_ss_flags(sp) | 4002 (current->sas_ss_flags & SS_FLAG_BITS); 4003 } 4004 4005 if (ss) { 4006 void __user *ss_sp = ss->ss_sp; 4007 size_t ss_size = ss->ss_size; 4008 unsigned ss_flags = ss->ss_flags; 4009 int ss_mode; 4010 4011 if (unlikely(on_sig_stack(sp))) 4012 return -EPERM; 4013 4014 ss_mode = ss_flags & ~SS_FLAG_BITS; 4015 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK && 4016 ss_mode != 0)) 4017 return -EINVAL; 4018 4019 if (ss_mode == SS_DISABLE) { 4020 ss_size = 0; 4021 ss_sp = NULL; 4022 } else { 4023 if (unlikely(ss_size < min_ss_size)) 4024 return -ENOMEM; 4025 } 4026 4027 t->sas_ss_sp = (unsigned long) ss_sp; 4028 t->sas_ss_size = ss_size; 4029 t->sas_ss_flags = ss_flags; 4030 } 4031 return 0; 4032 } 4033 4034 SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss) 4035 { 4036 stack_t new, old; 4037 int err; 4038 if (uss && copy_from_user(&new, uss, sizeof(stack_t))) 4039 return -EFAULT; 4040 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL, 4041 current_user_stack_pointer(), 4042 MINSIGSTKSZ); 4043 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t))) 4044 err = -EFAULT; 4045 return err; 4046 } 4047 4048 int restore_altstack(const stack_t __user *uss) 4049 { 4050 stack_t new; 4051 if (copy_from_user(&new, uss, sizeof(stack_t))) 4052 return -EFAULT; 4053 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer(), 4054 MINSIGSTKSZ); 4055 /* squash all but EFAULT for now */ 4056 return 0; 4057 } 4058 4059 int __save_altstack(stack_t __user *uss, unsigned long sp) 4060 { 4061 struct task_struct *t = current; 4062 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) | 4063 __put_user(t->sas_ss_flags, &uss->ss_flags) | 4064 __put_user(t->sas_ss_size, &uss->ss_size); 4065 if (err) 4066 return err; 4067 if (t->sas_ss_flags & SS_AUTODISARM) 4068 sas_ss_reset(t); 4069 return 0; 4070 } 4071 4072 #ifdef CONFIG_COMPAT 4073 static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr, 4074 compat_stack_t __user *uoss_ptr) 4075 { 4076 stack_t uss, uoss; 4077 int ret; 4078 4079 if (uss_ptr) { 4080 compat_stack_t uss32; 4081 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t))) 4082 return -EFAULT; 4083 uss.ss_sp = compat_ptr(uss32.ss_sp); 4084 uss.ss_flags = uss32.ss_flags; 4085 uss.ss_size = uss32.ss_size; 4086 } 4087 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss, 4088 compat_user_stack_pointer(), 4089 COMPAT_MINSIGSTKSZ); 4090 if (ret >= 0 && uoss_ptr) { 4091 compat_stack_t old; 4092 memset(&old, 0, sizeof(old)); 4093 old.ss_sp = ptr_to_compat(uoss.ss_sp); 4094 old.ss_flags = uoss.ss_flags; 4095 old.ss_size = uoss.ss_size; 4096 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t))) 4097 ret = -EFAULT; 4098 } 4099 return ret; 4100 } 4101 4102 COMPAT_SYSCALL_DEFINE2(sigaltstack, 4103 const compat_stack_t __user *, uss_ptr, 4104 compat_stack_t __user *, uoss_ptr) 4105 { 4106 return do_compat_sigaltstack(uss_ptr, uoss_ptr); 4107 } 4108 4109 int compat_restore_altstack(const compat_stack_t __user *uss) 4110 { 4111 int err = do_compat_sigaltstack(uss, NULL); 4112 /* squash all but -EFAULT for now */ 4113 return err == -EFAULT ? err : 0; 4114 } 4115 4116 int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp) 4117 { 4118 int err; 4119 struct task_struct *t = current; 4120 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), 4121 &uss->ss_sp) | 4122 __put_user(t->sas_ss_flags, &uss->ss_flags) | 4123 __put_user(t->sas_ss_size, &uss->ss_size); 4124 if (err) 4125 return err; 4126 if (t->sas_ss_flags & SS_AUTODISARM) 4127 sas_ss_reset(t); 4128 return 0; 4129 } 4130 #endif 4131 4132 #ifdef __ARCH_WANT_SYS_SIGPENDING 4133 4134 /** 4135 * sys_sigpending - examine pending signals 4136 * @uset: where mask of pending signal is returned 4137 */ 4138 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset) 4139 { 4140 sigset_t set; 4141 4142 if (sizeof(old_sigset_t) > sizeof(*uset)) 4143 return -EINVAL; 4144 4145 do_sigpending(&set); 4146 4147 if (copy_to_user(uset, &set, sizeof(old_sigset_t))) 4148 return -EFAULT; 4149 4150 return 0; 4151 } 4152 4153 #ifdef CONFIG_COMPAT 4154 COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32) 4155 { 4156 sigset_t set; 4157 4158 do_sigpending(&set); 4159 4160 return put_user(set.sig[0], set32); 4161 } 4162 #endif 4163 4164 #endif 4165 4166 #ifdef __ARCH_WANT_SYS_SIGPROCMASK 4167 /** 4168 * sys_sigprocmask - examine and change blocked signals 4169 * @how: whether to add, remove, or set signals 4170 * @nset: signals to add or remove (if non-null) 4171 * @oset: previous value of signal mask if non-null 4172 * 4173 * Some platforms have their own version with special arguments; 4174 * others support only sys_rt_sigprocmask. 4175 */ 4176 4177 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset, 4178 old_sigset_t __user *, oset) 4179 { 4180 old_sigset_t old_set, new_set; 4181 sigset_t new_blocked; 4182 4183 old_set = current->blocked.sig[0]; 4184 4185 if (nset) { 4186 if (copy_from_user(&new_set, nset, sizeof(*nset))) 4187 return -EFAULT; 4188 4189 new_blocked = current->blocked; 4190 4191 switch (how) { 4192 case SIG_BLOCK: 4193 sigaddsetmask(&new_blocked, new_set); 4194 break; 4195 case SIG_UNBLOCK: 4196 sigdelsetmask(&new_blocked, new_set); 4197 break; 4198 case SIG_SETMASK: 4199 new_blocked.sig[0] = new_set; 4200 break; 4201 default: 4202 return -EINVAL; 4203 } 4204 4205 set_current_blocked(&new_blocked); 4206 } 4207 4208 if (oset) { 4209 if (copy_to_user(oset, &old_set, sizeof(*oset))) 4210 return -EFAULT; 4211 } 4212 4213 return 0; 4214 } 4215 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */ 4216 4217 #ifndef CONFIG_ODD_RT_SIGACTION 4218 /** 4219 * sys_rt_sigaction - alter an action taken by a process 4220 * @sig: signal to be sent 4221 * @act: new sigaction 4222 * @oact: used to save the previous sigaction 4223 * @sigsetsize: size of sigset_t type 4224 */ 4225 SYSCALL_DEFINE4(rt_sigaction, int, sig, 4226 const struct sigaction __user *, act, 4227 struct sigaction __user *, oact, 4228 size_t, sigsetsize) 4229 { 4230 struct k_sigaction new_sa, old_sa; 4231 int ret; 4232 4233 /* XXX: Don't preclude handling different sized sigset_t's. */ 4234 if (sigsetsize != sizeof(sigset_t)) 4235 return -EINVAL; 4236 4237 if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa))) 4238 return -EFAULT; 4239 4240 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL); 4241 if (ret) 4242 return ret; 4243 4244 if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa))) 4245 return -EFAULT; 4246 4247 return 0; 4248 } 4249 #ifdef CONFIG_COMPAT 4250 COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig, 4251 const struct compat_sigaction __user *, act, 4252 struct compat_sigaction __user *, oact, 4253 compat_size_t, sigsetsize) 4254 { 4255 struct k_sigaction new_ka, old_ka; 4256 #ifdef __ARCH_HAS_SA_RESTORER 4257 compat_uptr_t restorer; 4258 #endif 4259 int ret; 4260 4261 /* XXX: Don't preclude handling different sized sigset_t's. */ 4262 if (sigsetsize != sizeof(compat_sigset_t)) 4263 return -EINVAL; 4264 4265 if (act) { 4266 compat_uptr_t handler; 4267 ret = get_user(handler, &act->sa_handler); 4268 new_ka.sa.sa_handler = compat_ptr(handler); 4269 #ifdef __ARCH_HAS_SA_RESTORER 4270 ret |= get_user(restorer, &act->sa_restorer); 4271 new_ka.sa.sa_restorer = compat_ptr(restorer); 4272 #endif 4273 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask); 4274 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags); 4275 if (ret) 4276 return -EFAULT; 4277 } 4278 4279 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); 4280 if (!ret && oact) { 4281 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), 4282 &oact->sa_handler); 4283 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask, 4284 sizeof(oact->sa_mask)); 4285 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags); 4286 #ifdef __ARCH_HAS_SA_RESTORER 4287 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer), 4288 &oact->sa_restorer); 4289 #endif 4290 } 4291 return ret; 4292 } 4293 #endif 4294 #endif /* !CONFIG_ODD_RT_SIGACTION */ 4295 4296 #ifdef CONFIG_OLD_SIGACTION 4297 SYSCALL_DEFINE3(sigaction, int, sig, 4298 const struct old_sigaction __user *, act, 4299 struct old_sigaction __user *, oact) 4300 { 4301 struct k_sigaction new_ka, old_ka; 4302 int ret; 4303 4304 if (act) { 4305 old_sigset_t mask; 4306 if (!access_ok(act, sizeof(*act)) || 4307 __get_user(new_ka.sa.sa_handler, &act->sa_handler) || 4308 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) || 4309 __get_user(new_ka.sa.sa_flags, &act->sa_flags) || 4310 __get_user(mask, &act->sa_mask)) 4311 return -EFAULT; 4312 #ifdef __ARCH_HAS_KA_RESTORER 4313 new_ka.ka_restorer = NULL; 4314 #endif 4315 siginitset(&new_ka.sa.sa_mask, mask); 4316 } 4317 4318 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); 4319 4320 if (!ret && oact) { 4321 if (!access_ok(oact, sizeof(*oact)) || 4322 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) || 4323 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) || 4324 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) || 4325 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask)) 4326 return -EFAULT; 4327 } 4328 4329 return ret; 4330 } 4331 #endif 4332 #ifdef CONFIG_COMPAT_OLD_SIGACTION 4333 COMPAT_SYSCALL_DEFINE3(sigaction, int, sig, 4334 const struct compat_old_sigaction __user *, act, 4335 struct compat_old_sigaction __user *, oact) 4336 { 4337 struct k_sigaction new_ka, old_ka; 4338 int ret; 4339 compat_old_sigset_t mask; 4340 compat_uptr_t handler, restorer; 4341 4342 if (act) { 4343 if (!access_ok(act, sizeof(*act)) || 4344 __get_user(handler, &act->sa_handler) || 4345 __get_user(restorer, &act->sa_restorer) || 4346 __get_user(new_ka.sa.sa_flags, &act->sa_flags) || 4347 __get_user(mask, &act->sa_mask)) 4348 return -EFAULT; 4349 4350 #ifdef __ARCH_HAS_KA_RESTORER 4351 new_ka.ka_restorer = NULL; 4352 #endif 4353 new_ka.sa.sa_handler = compat_ptr(handler); 4354 new_ka.sa.sa_restorer = compat_ptr(restorer); 4355 siginitset(&new_ka.sa.sa_mask, mask); 4356 } 4357 4358 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); 4359 4360 if (!ret && oact) { 4361 if (!access_ok(oact, sizeof(*oact)) || 4362 __put_user(ptr_to_compat(old_ka.sa.sa_handler), 4363 &oact->sa_handler) || 4364 __put_user(ptr_to_compat(old_ka.sa.sa_restorer), 4365 &oact->sa_restorer) || 4366 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) || 4367 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask)) 4368 return -EFAULT; 4369 } 4370 return ret; 4371 } 4372 #endif 4373 4374 #ifdef CONFIG_SGETMASK_SYSCALL 4375 4376 /* 4377 * For backwards compatibility. Functionality superseded by sigprocmask. 4378 */ 4379 SYSCALL_DEFINE0(sgetmask) 4380 { 4381 /* SMP safe */ 4382 return current->blocked.sig[0]; 4383 } 4384 4385 SYSCALL_DEFINE1(ssetmask, int, newmask) 4386 { 4387 int old = current->blocked.sig[0]; 4388 sigset_t newset; 4389 4390 siginitset(&newset, newmask); 4391 set_current_blocked(&newset); 4392 4393 return old; 4394 } 4395 #endif /* CONFIG_SGETMASK_SYSCALL */ 4396 4397 #ifdef __ARCH_WANT_SYS_SIGNAL 4398 /* 4399 * For backwards compatibility. Functionality superseded by sigaction. 4400 */ 4401 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler) 4402 { 4403 struct k_sigaction new_sa, old_sa; 4404 int ret; 4405 4406 new_sa.sa.sa_handler = handler; 4407 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK; 4408 sigemptyset(&new_sa.sa.sa_mask); 4409 4410 ret = do_sigaction(sig, &new_sa, &old_sa); 4411 4412 return ret ? ret : (unsigned long)old_sa.sa.sa_handler; 4413 } 4414 #endif /* __ARCH_WANT_SYS_SIGNAL */ 4415 4416 #ifdef __ARCH_WANT_SYS_PAUSE 4417 4418 SYSCALL_DEFINE0(pause) 4419 { 4420 while (!signal_pending(current)) { 4421 __set_current_state(TASK_INTERRUPTIBLE); 4422 schedule(); 4423 } 4424 return -ERESTARTNOHAND; 4425 } 4426 4427 #endif 4428 4429 static int sigsuspend(sigset_t *set) 4430 { 4431 current->saved_sigmask = current->blocked; 4432 set_current_blocked(set); 4433 4434 while (!signal_pending(current)) { 4435 __set_current_state(TASK_INTERRUPTIBLE); 4436 schedule(); 4437 } 4438 set_restore_sigmask(); 4439 return -ERESTARTNOHAND; 4440 } 4441 4442 /** 4443 * sys_rt_sigsuspend - replace the signal mask for a value with the 4444 * @unewset value until a signal is received 4445 * @unewset: new signal mask value 4446 * @sigsetsize: size of sigset_t type 4447 */ 4448 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize) 4449 { 4450 sigset_t newset; 4451 4452 /* XXX: Don't preclude handling different sized sigset_t's. */ 4453 if (sigsetsize != sizeof(sigset_t)) 4454 return -EINVAL; 4455 4456 if (copy_from_user(&newset, unewset, sizeof(newset))) 4457 return -EFAULT; 4458 return sigsuspend(&newset); 4459 } 4460 4461 #ifdef CONFIG_COMPAT 4462 COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize) 4463 { 4464 sigset_t newset; 4465 4466 /* XXX: Don't preclude handling different sized sigset_t's. */ 4467 if (sigsetsize != sizeof(sigset_t)) 4468 return -EINVAL; 4469 4470 if (get_compat_sigset(&newset, unewset)) 4471 return -EFAULT; 4472 return sigsuspend(&newset); 4473 } 4474 #endif 4475 4476 #ifdef CONFIG_OLD_SIGSUSPEND 4477 SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask) 4478 { 4479 sigset_t blocked; 4480 siginitset(&blocked, mask); 4481 return sigsuspend(&blocked); 4482 } 4483 #endif 4484 #ifdef CONFIG_OLD_SIGSUSPEND3 4485 SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask) 4486 { 4487 sigset_t blocked; 4488 siginitset(&blocked, mask); 4489 return sigsuspend(&blocked); 4490 } 4491 #endif 4492 4493 __weak const char *arch_vma_name(struct vm_area_struct *vma) 4494 { 4495 return NULL; 4496 } 4497 4498 static inline void siginfo_buildtime_checks(void) 4499 { 4500 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE); 4501 4502 /* Verify the offsets in the two siginfos match */ 4503 #define CHECK_OFFSET(field) \ 4504 BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field)) 4505 4506 /* kill */ 4507 CHECK_OFFSET(si_pid); 4508 CHECK_OFFSET(si_uid); 4509 4510 /* timer */ 4511 CHECK_OFFSET(si_tid); 4512 CHECK_OFFSET(si_overrun); 4513 CHECK_OFFSET(si_value); 4514 4515 /* rt */ 4516 CHECK_OFFSET(si_pid); 4517 CHECK_OFFSET(si_uid); 4518 CHECK_OFFSET(si_value); 4519 4520 /* sigchld */ 4521 CHECK_OFFSET(si_pid); 4522 CHECK_OFFSET(si_uid); 4523 CHECK_OFFSET(si_status); 4524 CHECK_OFFSET(si_utime); 4525 CHECK_OFFSET(si_stime); 4526 4527 /* sigfault */ 4528 CHECK_OFFSET(si_addr); 4529 CHECK_OFFSET(si_addr_lsb); 4530 CHECK_OFFSET(si_lower); 4531 CHECK_OFFSET(si_upper); 4532 CHECK_OFFSET(si_pkey); 4533 4534 /* sigpoll */ 4535 CHECK_OFFSET(si_band); 4536 CHECK_OFFSET(si_fd); 4537 4538 /* sigsys */ 4539 CHECK_OFFSET(si_call_addr); 4540 CHECK_OFFSET(si_syscall); 4541 CHECK_OFFSET(si_arch); 4542 #undef CHECK_OFFSET 4543 4544 /* usb asyncio */ 4545 BUILD_BUG_ON(offsetof(struct siginfo, si_pid) != 4546 offsetof(struct siginfo, si_addr)); 4547 if (sizeof(int) == sizeof(void __user *)) { 4548 BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) != 4549 sizeof(void __user *)); 4550 } else { 4551 BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) + 4552 sizeof_field(struct siginfo, si_uid)) != 4553 sizeof(void __user *)); 4554 BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) != 4555 offsetof(struct siginfo, si_uid)); 4556 } 4557 #ifdef CONFIG_COMPAT 4558 BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) != 4559 offsetof(struct compat_siginfo, si_addr)); 4560 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) != 4561 sizeof(compat_uptr_t)); 4562 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) != 4563 sizeof_field(struct siginfo, si_pid)); 4564 #endif 4565 } 4566 4567 void __init signals_init(void) 4568 { 4569 siginfo_buildtime_checks(); 4570 4571 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC); 4572 } 4573 4574 #ifdef CONFIG_KGDB_KDB 4575 #include <linux/kdb.h> 4576 /* 4577 * kdb_send_sig - Allows kdb to send signals without exposing 4578 * signal internals. This function checks if the required locks are 4579 * available before calling the main signal code, to avoid kdb 4580 * deadlocks. 4581 */ 4582 void kdb_send_sig(struct task_struct *t, int sig) 4583 { 4584 static struct task_struct *kdb_prev_t; 4585 int new_t, ret; 4586 if (!spin_trylock(&t->sighand->siglock)) { 4587 kdb_printf("Can't do kill command now.\n" 4588 "The sigmask lock is held somewhere else in " 4589 "kernel, try again later\n"); 4590 return; 4591 } 4592 new_t = kdb_prev_t != t; 4593 kdb_prev_t = t; 4594 if (t->state != TASK_RUNNING && new_t) { 4595 spin_unlock(&t->sighand->siglock); 4596 kdb_printf("Process is not RUNNING, sending a signal from " 4597 "kdb risks deadlock\n" 4598 "on the run queue locks. " 4599 "The signal has _not_ been sent.\n" 4600 "Reissue the kill command if you want to risk " 4601 "the deadlock.\n"); 4602 return; 4603 } 4604 ret = send_signal(sig, SEND_SIG_PRIV, t, PIDTYPE_PID); 4605 spin_unlock(&t->sighand->siglock); 4606 if (ret) 4607 kdb_printf("Fail to deliver Signal %d to process %d.\n", 4608 sig, t->pid); 4609 else 4610 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid); 4611 } 4612 #endif /* CONFIG_KGDB_KDB */ 4613