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/cgroup.h> 47 #include <linux/audit.h> 48 49 #define CREATE_TRACE_POINTS 50 #include <trace/events/signal.h> 51 52 #include <asm/param.h> 53 #include <linux/uaccess.h> 54 #include <asm/unistd.h> 55 #include <asm/siginfo.h> 56 #include <asm/cacheflush.h> 57 58 /* 59 * SLAB caches for signal bits. 60 */ 61 62 static struct kmem_cache *sigqueue_cachep; 63 64 int print_fatal_signals __read_mostly; 65 66 static void __user *sig_handler(struct task_struct *t, int sig) 67 { 68 return t->sighand->action[sig - 1].sa.sa_handler; 69 } 70 71 static inline bool sig_handler_ignored(void __user *handler, int sig) 72 { 73 /* Is it explicitly or implicitly ignored? */ 74 return handler == SIG_IGN || 75 (handler == SIG_DFL && sig_kernel_ignore(sig)); 76 } 77 78 static bool sig_task_ignored(struct task_struct *t, int sig, bool force) 79 { 80 void __user *handler; 81 82 handler = sig_handler(t, sig); 83 84 /* SIGKILL and SIGSTOP may not be sent to the global init */ 85 if (unlikely(is_global_init(t) && sig_kernel_only(sig))) 86 return true; 87 88 if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) && 89 handler == SIG_DFL && !(force && sig_kernel_only(sig))) 90 return true; 91 92 /* Only allow kernel generated signals to this kthread */ 93 if (unlikely((t->flags & PF_KTHREAD) && 94 (handler == SIG_KTHREAD_KERNEL) && !force)) 95 return true; 96 97 return sig_handler_ignored(handler, sig); 98 } 99 100 static bool sig_ignored(struct task_struct *t, int sig, bool force) 101 { 102 /* 103 * Blocked signals are never ignored, since the 104 * signal handler may change by the time it is 105 * unblocked. 106 */ 107 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig)) 108 return false; 109 110 /* 111 * Tracers may want to know about even ignored signal unless it 112 * is SIGKILL which can't be reported anyway but can be ignored 113 * by SIGNAL_UNKILLABLE task. 114 */ 115 if (t->ptrace && sig != SIGKILL) 116 return false; 117 118 return sig_task_ignored(t, sig, force); 119 } 120 121 /* 122 * Re-calculate pending state from the set of locally pending 123 * signals, globally pending signals, and blocked signals. 124 */ 125 static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked) 126 { 127 unsigned long ready; 128 long i; 129 130 switch (_NSIG_WORDS) { 131 default: 132 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;) 133 ready |= signal->sig[i] &~ blocked->sig[i]; 134 break; 135 136 case 4: ready = signal->sig[3] &~ blocked->sig[3]; 137 ready |= signal->sig[2] &~ blocked->sig[2]; 138 ready |= signal->sig[1] &~ blocked->sig[1]; 139 ready |= signal->sig[0] &~ blocked->sig[0]; 140 break; 141 142 case 2: ready = signal->sig[1] &~ blocked->sig[1]; 143 ready |= signal->sig[0] &~ blocked->sig[0]; 144 break; 145 146 case 1: ready = signal->sig[0] &~ blocked->sig[0]; 147 } 148 return ready != 0; 149 } 150 151 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b)) 152 153 static bool recalc_sigpending_tsk(struct task_struct *t) 154 { 155 if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) || 156 PENDING(&t->pending, &t->blocked) || 157 PENDING(&t->signal->shared_pending, &t->blocked) || 158 cgroup_task_frozen(t)) { 159 set_tsk_thread_flag(t, TIF_SIGPENDING); 160 return true; 161 } 162 163 /* 164 * We must never clear the flag in another thread, or in current 165 * when it's possible the current syscall is returning -ERESTART*. 166 * So we don't clear it here, and only callers who know they should do. 167 */ 168 return false; 169 } 170 171 /* 172 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up. 173 * This is superfluous when called on current, the wakeup is a harmless no-op. 174 */ 175 void recalc_sigpending_and_wake(struct task_struct *t) 176 { 177 if (recalc_sigpending_tsk(t)) 178 signal_wake_up(t, 0); 179 } 180 181 void recalc_sigpending(void) 182 { 183 if (!recalc_sigpending_tsk(current) && !freezing(current)) 184 clear_thread_flag(TIF_SIGPENDING); 185 186 } 187 EXPORT_SYMBOL(recalc_sigpending); 188 189 void calculate_sigpending(void) 190 { 191 /* Have any signals or users of TIF_SIGPENDING been delayed 192 * until after fork? 193 */ 194 spin_lock_irq(¤t->sighand->siglock); 195 set_tsk_thread_flag(current, TIF_SIGPENDING); 196 recalc_sigpending(); 197 spin_unlock_irq(¤t->sighand->siglock); 198 } 199 200 /* Given the mask, find the first available signal that should be serviced. */ 201 202 #define SYNCHRONOUS_MASK \ 203 (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \ 204 sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS)) 205 206 int next_signal(struct sigpending *pending, sigset_t *mask) 207 { 208 unsigned long i, *s, *m, x; 209 int sig = 0; 210 211 s = pending->signal.sig; 212 m = mask->sig; 213 214 /* 215 * Handle the first word specially: it contains the 216 * synchronous signals that need to be dequeued first. 217 */ 218 x = *s &~ *m; 219 if (x) { 220 if (x & SYNCHRONOUS_MASK) 221 x &= SYNCHRONOUS_MASK; 222 sig = ffz(~x) + 1; 223 return sig; 224 } 225 226 switch (_NSIG_WORDS) { 227 default: 228 for (i = 1; i < _NSIG_WORDS; ++i) { 229 x = *++s &~ *++m; 230 if (!x) 231 continue; 232 sig = ffz(~x) + i*_NSIG_BPW + 1; 233 break; 234 } 235 break; 236 237 case 2: 238 x = s[1] &~ m[1]; 239 if (!x) 240 break; 241 sig = ffz(~x) + _NSIG_BPW + 1; 242 break; 243 244 case 1: 245 /* Nothing to do */ 246 break; 247 } 248 249 return sig; 250 } 251 252 static inline void print_dropped_signal(int sig) 253 { 254 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10); 255 256 if (!print_fatal_signals) 257 return; 258 259 if (!__ratelimit(&ratelimit_state)) 260 return; 261 262 pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n", 263 current->comm, current->pid, sig); 264 } 265 266 /** 267 * task_set_jobctl_pending - set jobctl pending bits 268 * @task: target task 269 * @mask: pending bits to set 270 * 271 * Clear @mask from @task->jobctl. @mask must be subset of 272 * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK | 273 * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is 274 * cleared. If @task is already being killed or exiting, this function 275 * becomes noop. 276 * 277 * CONTEXT: 278 * Must be called with @task->sighand->siglock held. 279 * 280 * RETURNS: 281 * %true if @mask is set, %false if made noop because @task was dying. 282 */ 283 bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask) 284 { 285 BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME | 286 JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING)); 287 BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK)); 288 289 if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING))) 290 return false; 291 292 if (mask & JOBCTL_STOP_SIGMASK) 293 task->jobctl &= ~JOBCTL_STOP_SIGMASK; 294 295 task->jobctl |= mask; 296 return true; 297 } 298 299 /** 300 * task_clear_jobctl_trapping - clear jobctl trapping bit 301 * @task: target task 302 * 303 * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED. 304 * Clear it and wake up the ptracer. Note that we don't need any further 305 * locking. @task->siglock guarantees that @task->parent points to the 306 * ptracer. 307 * 308 * CONTEXT: 309 * Must be called with @task->sighand->siglock held. 310 */ 311 void task_clear_jobctl_trapping(struct task_struct *task) 312 { 313 if (unlikely(task->jobctl & JOBCTL_TRAPPING)) { 314 task->jobctl &= ~JOBCTL_TRAPPING; 315 smp_mb(); /* advised by wake_up_bit() */ 316 wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT); 317 } 318 } 319 320 /** 321 * task_clear_jobctl_pending - clear jobctl pending bits 322 * @task: target task 323 * @mask: pending bits to clear 324 * 325 * Clear @mask from @task->jobctl. @mask must be subset of 326 * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other 327 * STOP bits are cleared together. 328 * 329 * If clearing of @mask leaves no stop or trap pending, this function calls 330 * task_clear_jobctl_trapping(). 331 * 332 * CONTEXT: 333 * Must be called with @task->sighand->siglock held. 334 */ 335 void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask) 336 { 337 BUG_ON(mask & ~JOBCTL_PENDING_MASK); 338 339 if (mask & JOBCTL_STOP_PENDING) 340 mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED; 341 342 task->jobctl &= ~mask; 343 344 if (!(task->jobctl & JOBCTL_PENDING_MASK)) 345 task_clear_jobctl_trapping(task); 346 } 347 348 /** 349 * task_participate_group_stop - participate in a group stop 350 * @task: task participating in a group stop 351 * 352 * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop. 353 * Group stop states are cleared and the group stop count is consumed if 354 * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group 355 * stop, the appropriate `SIGNAL_*` flags are set. 356 * 357 * CONTEXT: 358 * Must be called with @task->sighand->siglock held. 359 * 360 * RETURNS: 361 * %true if group stop completion should be notified to the parent, %false 362 * otherwise. 363 */ 364 static bool task_participate_group_stop(struct task_struct *task) 365 { 366 struct signal_struct *sig = task->signal; 367 bool consume = task->jobctl & JOBCTL_STOP_CONSUME; 368 369 WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING)); 370 371 task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING); 372 373 if (!consume) 374 return false; 375 376 if (!WARN_ON_ONCE(sig->group_stop_count == 0)) 377 sig->group_stop_count--; 378 379 /* 380 * Tell the caller to notify completion iff we are entering into a 381 * fresh group stop. Read comment in do_signal_stop() for details. 382 */ 383 if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) { 384 signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED); 385 return true; 386 } 387 return false; 388 } 389 390 void task_join_group_stop(struct task_struct *task) 391 { 392 unsigned long mask = current->jobctl & JOBCTL_STOP_SIGMASK; 393 struct signal_struct *sig = current->signal; 394 395 if (sig->group_stop_count) { 396 sig->group_stop_count++; 397 mask |= JOBCTL_STOP_CONSUME; 398 } else if (!(sig->flags & SIGNAL_STOP_STOPPED)) 399 return; 400 401 /* Have the new thread join an on-going signal group stop */ 402 task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING); 403 } 404 405 /* 406 * allocate a new signal queue record 407 * - this may be called without locks if and only if t == current, otherwise an 408 * appropriate lock must be held to stop the target task from exiting 409 */ 410 static struct sigqueue * 411 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags, 412 int override_rlimit, const unsigned int sigqueue_flags) 413 { 414 struct sigqueue *q = NULL; 415 struct ucounts *ucounts = NULL; 416 long sigpending; 417 418 /* 419 * Protect access to @t credentials. This can go away when all 420 * callers hold rcu read lock. 421 * 422 * NOTE! A pending signal will hold on to the user refcount, 423 * and we get/put the refcount only when the sigpending count 424 * changes from/to zero. 425 */ 426 rcu_read_lock(); 427 ucounts = task_ucounts(t); 428 sigpending = inc_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING, 1); 429 if (sigpending == 1) 430 ucounts = get_ucounts(ucounts); 431 rcu_read_unlock(); 432 433 if (override_rlimit || (sigpending < LONG_MAX && sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) { 434 q = kmem_cache_alloc(sigqueue_cachep, gfp_flags); 435 } else { 436 print_dropped_signal(sig); 437 } 438 439 if (unlikely(q == NULL)) { 440 if (ucounts && dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING, 1)) 441 put_ucounts(ucounts); 442 } else { 443 INIT_LIST_HEAD(&q->list); 444 q->flags = sigqueue_flags; 445 q->ucounts = ucounts; 446 } 447 return q; 448 } 449 450 static void __sigqueue_free(struct sigqueue *q) 451 { 452 if (q->flags & SIGQUEUE_PREALLOC) 453 return; 454 if (q->ucounts && dec_rlimit_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING, 1)) { 455 put_ucounts(q->ucounts); 456 q->ucounts = NULL; 457 } 458 kmem_cache_free(sigqueue_cachep, q); 459 } 460 461 void flush_sigqueue(struct sigpending *queue) 462 { 463 struct sigqueue *q; 464 465 sigemptyset(&queue->signal); 466 while (!list_empty(&queue->list)) { 467 q = list_entry(queue->list.next, struct sigqueue , list); 468 list_del_init(&q->list); 469 __sigqueue_free(q); 470 } 471 } 472 473 /* 474 * Flush all pending signals for this kthread. 475 */ 476 void flush_signals(struct task_struct *t) 477 { 478 unsigned long flags; 479 480 spin_lock_irqsave(&t->sighand->siglock, flags); 481 clear_tsk_thread_flag(t, TIF_SIGPENDING); 482 flush_sigqueue(&t->pending); 483 flush_sigqueue(&t->signal->shared_pending); 484 spin_unlock_irqrestore(&t->sighand->siglock, flags); 485 } 486 EXPORT_SYMBOL(flush_signals); 487 488 #ifdef CONFIG_POSIX_TIMERS 489 static void __flush_itimer_signals(struct sigpending *pending) 490 { 491 sigset_t signal, retain; 492 struct sigqueue *q, *n; 493 494 signal = pending->signal; 495 sigemptyset(&retain); 496 497 list_for_each_entry_safe(q, n, &pending->list, list) { 498 int sig = q->info.si_signo; 499 500 if (likely(q->info.si_code != SI_TIMER)) { 501 sigaddset(&retain, sig); 502 } else { 503 sigdelset(&signal, sig); 504 list_del_init(&q->list); 505 __sigqueue_free(q); 506 } 507 } 508 509 sigorsets(&pending->signal, &signal, &retain); 510 } 511 512 void flush_itimer_signals(void) 513 { 514 struct task_struct *tsk = current; 515 unsigned long flags; 516 517 spin_lock_irqsave(&tsk->sighand->siglock, flags); 518 __flush_itimer_signals(&tsk->pending); 519 __flush_itimer_signals(&tsk->signal->shared_pending); 520 spin_unlock_irqrestore(&tsk->sighand->siglock, flags); 521 } 522 #endif 523 524 void ignore_signals(struct task_struct *t) 525 { 526 int i; 527 528 for (i = 0; i < _NSIG; ++i) 529 t->sighand->action[i].sa.sa_handler = SIG_IGN; 530 531 flush_signals(t); 532 } 533 534 /* 535 * Flush all handlers for a task. 536 */ 537 538 void 539 flush_signal_handlers(struct task_struct *t, int force_default) 540 { 541 int i; 542 struct k_sigaction *ka = &t->sighand->action[0]; 543 for (i = _NSIG ; i != 0 ; i--) { 544 if (force_default || ka->sa.sa_handler != SIG_IGN) 545 ka->sa.sa_handler = SIG_DFL; 546 ka->sa.sa_flags = 0; 547 #ifdef __ARCH_HAS_SA_RESTORER 548 ka->sa.sa_restorer = NULL; 549 #endif 550 sigemptyset(&ka->sa.sa_mask); 551 ka++; 552 } 553 } 554 555 bool unhandled_signal(struct task_struct *tsk, int sig) 556 { 557 void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler; 558 if (is_global_init(tsk)) 559 return true; 560 561 if (handler != SIG_IGN && handler != SIG_DFL) 562 return false; 563 564 /* if ptraced, let the tracer determine */ 565 return !tsk->ptrace; 566 } 567 568 static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info, 569 bool *resched_timer) 570 { 571 struct sigqueue *q, *first = NULL; 572 573 /* 574 * Collect the siginfo appropriate to this signal. Check if 575 * there is another siginfo for the same signal. 576 */ 577 list_for_each_entry(q, &list->list, list) { 578 if (q->info.si_signo == sig) { 579 if (first) 580 goto still_pending; 581 first = q; 582 } 583 } 584 585 sigdelset(&list->signal, sig); 586 587 if (first) { 588 still_pending: 589 list_del_init(&first->list); 590 copy_siginfo(info, &first->info); 591 592 *resched_timer = 593 (first->flags & SIGQUEUE_PREALLOC) && 594 (info->si_code == SI_TIMER) && 595 (info->si_sys_private); 596 597 __sigqueue_free(first); 598 } else { 599 /* 600 * Ok, it wasn't in the queue. This must be 601 * a fast-pathed signal or we must have been 602 * out of queue space. So zero out the info. 603 */ 604 clear_siginfo(info); 605 info->si_signo = sig; 606 info->si_errno = 0; 607 info->si_code = SI_USER; 608 info->si_pid = 0; 609 info->si_uid = 0; 610 } 611 } 612 613 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask, 614 kernel_siginfo_t *info, bool *resched_timer) 615 { 616 int sig = next_signal(pending, mask); 617 618 if (sig) 619 collect_signal(sig, pending, info, resched_timer); 620 return sig; 621 } 622 623 /* 624 * Dequeue a signal and return the element to the caller, which is 625 * expected to free it. 626 * 627 * All callers have to hold the siglock. 628 */ 629 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, kernel_siginfo_t *info) 630 { 631 bool resched_timer = false; 632 int signr; 633 634 /* We only dequeue private signals from ourselves, we don't let 635 * signalfd steal them 636 */ 637 signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer); 638 if (!signr) { 639 signr = __dequeue_signal(&tsk->signal->shared_pending, 640 mask, info, &resched_timer); 641 #ifdef CONFIG_POSIX_TIMERS 642 /* 643 * itimer signal ? 644 * 645 * itimers are process shared and we restart periodic 646 * itimers in the signal delivery path to prevent DoS 647 * attacks in the high resolution timer case. This is 648 * compliant with the old way of self-restarting 649 * itimers, as the SIGALRM is a legacy signal and only 650 * queued once. Changing the restart behaviour to 651 * restart the timer in the signal dequeue path is 652 * reducing the timer noise on heavy loaded !highres 653 * systems too. 654 */ 655 if (unlikely(signr == SIGALRM)) { 656 struct hrtimer *tmr = &tsk->signal->real_timer; 657 658 if (!hrtimer_is_queued(tmr) && 659 tsk->signal->it_real_incr != 0) { 660 hrtimer_forward(tmr, tmr->base->get_time(), 661 tsk->signal->it_real_incr); 662 hrtimer_restart(tmr); 663 } 664 } 665 #endif 666 } 667 668 recalc_sigpending(); 669 if (!signr) 670 return 0; 671 672 if (unlikely(sig_kernel_stop(signr))) { 673 /* 674 * Set a marker that we have dequeued a stop signal. Our 675 * caller might release the siglock and then the pending 676 * stop signal it is about to process is no longer in the 677 * pending bitmasks, but must still be cleared by a SIGCONT 678 * (and overruled by a SIGKILL). So those cases clear this 679 * shared flag after we've set it. Note that this flag may 680 * remain set after the signal we return is ignored or 681 * handled. That doesn't matter because its only purpose 682 * is to alert stop-signal processing code when another 683 * processor has come along and cleared the flag. 684 */ 685 current->jobctl |= JOBCTL_STOP_DEQUEUED; 686 } 687 #ifdef CONFIG_POSIX_TIMERS 688 if (resched_timer) { 689 /* 690 * Release the siglock to ensure proper locking order 691 * of timer locks outside of siglocks. Note, we leave 692 * irqs disabled here, since the posix-timers code is 693 * about to disable them again anyway. 694 */ 695 spin_unlock(&tsk->sighand->siglock); 696 posixtimer_rearm(info); 697 spin_lock(&tsk->sighand->siglock); 698 699 /* Don't expose the si_sys_private value to userspace */ 700 info->si_sys_private = 0; 701 } 702 #endif 703 return signr; 704 } 705 EXPORT_SYMBOL_GPL(dequeue_signal); 706 707 static int dequeue_synchronous_signal(kernel_siginfo_t *info) 708 { 709 struct task_struct *tsk = current; 710 struct sigpending *pending = &tsk->pending; 711 struct sigqueue *q, *sync = NULL; 712 713 /* 714 * Might a synchronous signal be in the queue? 715 */ 716 if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK)) 717 return 0; 718 719 /* 720 * Return the first synchronous signal in the queue. 721 */ 722 list_for_each_entry(q, &pending->list, list) { 723 /* Synchronous signals have a positive si_code */ 724 if ((q->info.si_code > SI_USER) && 725 (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) { 726 sync = q; 727 goto next; 728 } 729 } 730 return 0; 731 next: 732 /* 733 * Check if there is another siginfo for the same signal. 734 */ 735 list_for_each_entry_continue(q, &pending->list, list) { 736 if (q->info.si_signo == sync->info.si_signo) 737 goto still_pending; 738 } 739 740 sigdelset(&pending->signal, sync->info.si_signo); 741 recalc_sigpending(); 742 still_pending: 743 list_del_init(&sync->list); 744 copy_siginfo(info, &sync->info); 745 __sigqueue_free(sync); 746 return info->si_signo; 747 } 748 749 /* 750 * Tell a process that it has a new active signal.. 751 * 752 * NOTE! we rely on the previous spin_lock to 753 * lock interrupts for us! We can only be called with 754 * "siglock" held, and the local interrupt must 755 * have been disabled when that got acquired! 756 * 757 * No need to set need_resched since signal event passing 758 * goes through ->blocked 759 */ 760 void signal_wake_up_state(struct task_struct *t, unsigned int state) 761 { 762 set_tsk_thread_flag(t, TIF_SIGPENDING); 763 /* 764 * TASK_WAKEKILL also means wake it up in the stopped/traced/killable 765 * case. We don't check t->state here because there is a race with it 766 * executing another processor and just now entering stopped state. 767 * By using wake_up_state, we ensure the process will wake up and 768 * handle its death signal. 769 */ 770 if (!wake_up_state(t, state | TASK_INTERRUPTIBLE)) 771 kick_process(t); 772 } 773 774 /* 775 * Remove signals in mask from the pending set and queue. 776 * Returns 1 if any signals were found. 777 * 778 * All callers must be holding the siglock. 779 */ 780 static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s) 781 { 782 struct sigqueue *q, *n; 783 sigset_t m; 784 785 sigandsets(&m, mask, &s->signal); 786 if (sigisemptyset(&m)) 787 return; 788 789 sigandnsets(&s->signal, &s->signal, mask); 790 list_for_each_entry_safe(q, n, &s->list, list) { 791 if (sigismember(mask, q->info.si_signo)) { 792 list_del_init(&q->list); 793 __sigqueue_free(q); 794 } 795 } 796 } 797 798 static inline int is_si_special(const struct kernel_siginfo *info) 799 { 800 return info <= SEND_SIG_PRIV; 801 } 802 803 static inline bool si_fromuser(const struct kernel_siginfo *info) 804 { 805 return info == SEND_SIG_NOINFO || 806 (!is_si_special(info) && SI_FROMUSER(info)); 807 } 808 809 /* 810 * called with RCU read lock from check_kill_permission() 811 */ 812 static bool kill_ok_by_cred(struct task_struct *t) 813 { 814 const struct cred *cred = current_cred(); 815 const struct cred *tcred = __task_cred(t); 816 817 return uid_eq(cred->euid, tcred->suid) || 818 uid_eq(cred->euid, tcred->uid) || 819 uid_eq(cred->uid, tcred->suid) || 820 uid_eq(cred->uid, tcred->uid) || 821 ns_capable(tcred->user_ns, CAP_KILL); 822 } 823 824 /* 825 * Bad permissions for sending the signal 826 * - the caller must hold the RCU read lock 827 */ 828 static int check_kill_permission(int sig, struct kernel_siginfo *info, 829 struct task_struct *t) 830 { 831 struct pid *sid; 832 int error; 833 834 if (!valid_signal(sig)) 835 return -EINVAL; 836 837 if (!si_fromuser(info)) 838 return 0; 839 840 error = audit_signal_info(sig, t); /* Let audit system see the signal */ 841 if (error) 842 return error; 843 844 if (!same_thread_group(current, t) && 845 !kill_ok_by_cred(t)) { 846 switch (sig) { 847 case SIGCONT: 848 sid = task_session(t); 849 /* 850 * We don't return the error if sid == NULL. The 851 * task was unhashed, the caller must notice this. 852 */ 853 if (!sid || sid == task_session(current)) 854 break; 855 fallthrough; 856 default: 857 return -EPERM; 858 } 859 } 860 861 return security_task_kill(t, info, sig, NULL); 862 } 863 864 /** 865 * ptrace_trap_notify - schedule trap to notify ptracer 866 * @t: tracee wanting to notify tracer 867 * 868 * This function schedules sticky ptrace trap which is cleared on the next 869 * TRAP_STOP to notify ptracer of an event. @t must have been seized by 870 * ptracer. 871 * 872 * If @t is running, STOP trap will be taken. If trapped for STOP and 873 * ptracer is listening for events, tracee is woken up so that it can 874 * re-trap for the new event. If trapped otherwise, STOP trap will be 875 * eventually taken without returning to userland after the existing traps 876 * are finished by PTRACE_CONT. 877 * 878 * CONTEXT: 879 * Must be called with @task->sighand->siglock held. 880 */ 881 static void ptrace_trap_notify(struct task_struct *t) 882 { 883 WARN_ON_ONCE(!(t->ptrace & PT_SEIZED)); 884 assert_spin_locked(&t->sighand->siglock); 885 886 task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY); 887 ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING); 888 } 889 890 /* 891 * Handle magic process-wide effects of stop/continue signals. Unlike 892 * the signal actions, these happen immediately at signal-generation 893 * time regardless of blocking, ignoring, or handling. This does the 894 * actual continuing for SIGCONT, but not the actual stopping for stop 895 * signals. The process stop is done as a signal action for SIG_DFL. 896 * 897 * Returns true if the signal should be actually delivered, otherwise 898 * it should be dropped. 899 */ 900 static bool prepare_signal(int sig, struct task_struct *p, bool force) 901 { 902 struct signal_struct *signal = p->signal; 903 struct task_struct *t; 904 sigset_t flush; 905 906 if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) { 907 if (!(signal->flags & SIGNAL_GROUP_EXIT)) 908 return sig == SIGKILL; 909 /* 910 * The process is in the middle of dying, nothing to do. 911 */ 912 } else if (sig_kernel_stop(sig)) { 913 /* 914 * This is a stop signal. Remove SIGCONT from all queues. 915 */ 916 siginitset(&flush, sigmask(SIGCONT)); 917 flush_sigqueue_mask(&flush, &signal->shared_pending); 918 for_each_thread(p, t) 919 flush_sigqueue_mask(&flush, &t->pending); 920 } else if (sig == SIGCONT) { 921 unsigned int why; 922 /* 923 * Remove all stop signals from all queues, wake all threads. 924 */ 925 siginitset(&flush, SIG_KERNEL_STOP_MASK); 926 flush_sigqueue_mask(&flush, &signal->shared_pending); 927 for_each_thread(p, t) { 928 flush_sigqueue_mask(&flush, &t->pending); 929 task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING); 930 if (likely(!(t->ptrace & PT_SEIZED))) 931 wake_up_state(t, __TASK_STOPPED); 932 else 933 ptrace_trap_notify(t); 934 } 935 936 /* 937 * Notify the parent with CLD_CONTINUED if we were stopped. 938 * 939 * If we were in the middle of a group stop, we pretend it 940 * was already finished, and then continued. Since SIGCHLD 941 * doesn't queue we report only CLD_STOPPED, as if the next 942 * CLD_CONTINUED was dropped. 943 */ 944 why = 0; 945 if (signal->flags & SIGNAL_STOP_STOPPED) 946 why |= SIGNAL_CLD_CONTINUED; 947 else if (signal->group_stop_count) 948 why |= SIGNAL_CLD_STOPPED; 949 950 if (why) { 951 /* 952 * The first thread which returns from do_signal_stop() 953 * will take ->siglock, notice SIGNAL_CLD_MASK, and 954 * notify its parent. See get_signal(). 955 */ 956 signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED); 957 signal->group_stop_count = 0; 958 signal->group_exit_code = 0; 959 } 960 } 961 962 return !sig_ignored(p, sig, force); 963 } 964 965 /* 966 * Test if P wants to take SIG. After we've checked all threads with this, 967 * it's equivalent to finding no threads not blocking SIG. Any threads not 968 * blocking SIG were ruled out because they are not running and already 969 * have pending signals. Such threads will dequeue from the shared queue 970 * as soon as they're available, so putting the signal on the shared queue 971 * will be equivalent to sending it to one such thread. 972 */ 973 static inline bool wants_signal(int sig, struct task_struct *p) 974 { 975 if (sigismember(&p->blocked, sig)) 976 return false; 977 978 if (p->flags & PF_EXITING) 979 return false; 980 981 if (sig == SIGKILL) 982 return true; 983 984 if (task_is_stopped_or_traced(p)) 985 return false; 986 987 return task_curr(p) || !task_sigpending(p); 988 } 989 990 static void complete_signal(int sig, struct task_struct *p, enum pid_type type) 991 { 992 struct signal_struct *signal = p->signal; 993 struct task_struct *t; 994 995 /* 996 * Now find a thread we can wake up to take the signal off the queue. 997 * 998 * If the main thread wants the signal, it gets first crack. 999 * Probably the least surprising to the average bear. 1000 */ 1001 if (wants_signal(sig, p)) 1002 t = p; 1003 else if ((type == PIDTYPE_PID) || thread_group_empty(p)) 1004 /* 1005 * There is just one thread and it does not need to be woken. 1006 * It will dequeue unblocked signals before it runs again. 1007 */ 1008 return; 1009 else { 1010 /* 1011 * Otherwise try to find a suitable thread. 1012 */ 1013 t = signal->curr_target; 1014 while (!wants_signal(sig, t)) { 1015 t = next_thread(t); 1016 if (t == signal->curr_target) 1017 /* 1018 * No thread needs to be woken. 1019 * Any eligible threads will see 1020 * the signal in the queue soon. 1021 */ 1022 return; 1023 } 1024 signal->curr_target = t; 1025 } 1026 1027 /* 1028 * Found a killable thread. If the signal will be fatal, 1029 * then start taking the whole group down immediately. 1030 */ 1031 if (sig_fatal(p, sig) && 1032 !(signal->flags & SIGNAL_GROUP_EXIT) && 1033 !sigismember(&t->real_blocked, sig) && 1034 (sig == SIGKILL || !p->ptrace)) { 1035 /* 1036 * This signal will be fatal to the whole group. 1037 */ 1038 if (!sig_kernel_coredump(sig)) { 1039 /* 1040 * Start a group exit and wake everybody up. 1041 * This way we don't have other threads 1042 * running and doing things after a slower 1043 * thread has the fatal signal pending. 1044 */ 1045 signal->flags = SIGNAL_GROUP_EXIT; 1046 signal->group_exit_code = sig; 1047 signal->group_stop_count = 0; 1048 t = p; 1049 do { 1050 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); 1051 sigaddset(&t->pending.signal, SIGKILL); 1052 signal_wake_up(t, 1); 1053 } while_each_thread(p, t); 1054 return; 1055 } 1056 } 1057 1058 /* 1059 * The signal is already in the shared-pending queue. 1060 * Tell the chosen thread to wake up and dequeue it. 1061 */ 1062 signal_wake_up(t, sig == SIGKILL); 1063 return; 1064 } 1065 1066 static inline bool legacy_queue(struct sigpending *signals, int sig) 1067 { 1068 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig); 1069 } 1070 1071 static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t, 1072 enum pid_type type, bool force) 1073 { 1074 struct sigpending *pending; 1075 struct sigqueue *q; 1076 int override_rlimit; 1077 int ret = 0, result; 1078 1079 assert_spin_locked(&t->sighand->siglock); 1080 1081 result = TRACE_SIGNAL_IGNORED; 1082 if (!prepare_signal(sig, t, force)) 1083 goto ret; 1084 1085 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending; 1086 /* 1087 * Short-circuit ignored signals and support queuing 1088 * exactly one non-rt signal, so that we can get more 1089 * detailed information about the cause of the signal. 1090 */ 1091 result = TRACE_SIGNAL_ALREADY_PENDING; 1092 if (legacy_queue(pending, sig)) 1093 goto ret; 1094 1095 result = TRACE_SIGNAL_DELIVERED; 1096 /* 1097 * Skip useless siginfo allocation for SIGKILL and kernel threads. 1098 */ 1099 if ((sig == SIGKILL) || (t->flags & PF_KTHREAD)) 1100 goto out_set; 1101 1102 /* 1103 * Real-time signals must be queued if sent by sigqueue, or 1104 * some other real-time mechanism. It is implementation 1105 * defined whether kill() does so. We attempt to do so, on 1106 * the principle of least surprise, but since kill is not 1107 * allowed to fail with EAGAIN when low on memory we just 1108 * make sure at least one signal gets delivered and don't 1109 * pass on the info struct. 1110 */ 1111 if (sig < SIGRTMIN) 1112 override_rlimit = (is_si_special(info) || info->si_code >= 0); 1113 else 1114 override_rlimit = 0; 1115 1116 q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit, 0); 1117 1118 if (q) { 1119 list_add_tail(&q->list, &pending->list); 1120 switch ((unsigned long) info) { 1121 case (unsigned long) SEND_SIG_NOINFO: 1122 clear_siginfo(&q->info); 1123 q->info.si_signo = sig; 1124 q->info.si_errno = 0; 1125 q->info.si_code = SI_USER; 1126 q->info.si_pid = task_tgid_nr_ns(current, 1127 task_active_pid_ns(t)); 1128 rcu_read_lock(); 1129 q->info.si_uid = 1130 from_kuid_munged(task_cred_xxx(t, user_ns), 1131 current_uid()); 1132 rcu_read_unlock(); 1133 break; 1134 case (unsigned long) SEND_SIG_PRIV: 1135 clear_siginfo(&q->info); 1136 q->info.si_signo = sig; 1137 q->info.si_errno = 0; 1138 q->info.si_code = SI_KERNEL; 1139 q->info.si_pid = 0; 1140 q->info.si_uid = 0; 1141 break; 1142 default: 1143 copy_siginfo(&q->info, info); 1144 break; 1145 } 1146 } else if (!is_si_special(info) && 1147 sig >= SIGRTMIN && info->si_code != SI_USER) { 1148 /* 1149 * Queue overflow, abort. We may abort if the 1150 * signal was rt and sent by user using something 1151 * other than kill(). 1152 */ 1153 result = TRACE_SIGNAL_OVERFLOW_FAIL; 1154 ret = -EAGAIN; 1155 goto ret; 1156 } else { 1157 /* 1158 * This is a silent loss of information. We still 1159 * send the signal, but the *info bits are lost. 1160 */ 1161 result = TRACE_SIGNAL_LOSE_INFO; 1162 } 1163 1164 out_set: 1165 signalfd_notify(t, sig); 1166 sigaddset(&pending->signal, sig); 1167 1168 /* Let multiprocess signals appear after on-going forks */ 1169 if (type > PIDTYPE_TGID) { 1170 struct multiprocess_signals *delayed; 1171 hlist_for_each_entry(delayed, &t->signal->multiprocess, node) { 1172 sigset_t *signal = &delayed->signal; 1173 /* Can't queue both a stop and a continue signal */ 1174 if (sig == SIGCONT) 1175 sigdelsetmask(signal, SIG_KERNEL_STOP_MASK); 1176 else if (sig_kernel_stop(sig)) 1177 sigdelset(signal, SIGCONT); 1178 sigaddset(signal, sig); 1179 } 1180 } 1181 1182 complete_signal(sig, t, type); 1183 ret: 1184 trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result); 1185 return ret; 1186 } 1187 1188 static inline bool has_si_pid_and_uid(struct kernel_siginfo *info) 1189 { 1190 bool ret = false; 1191 switch (siginfo_layout(info->si_signo, info->si_code)) { 1192 case SIL_KILL: 1193 case SIL_CHLD: 1194 case SIL_RT: 1195 ret = true; 1196 break; 1197 case SIL_TIMER: 1198 case SIL_POLL: 1199 case SIL_FAULT: 1200 case SIL_FAULT_TRAPNO: 1201 case SIL_FAULT_MCEERR: 1202 case SIL_FAULT_BNDERR: 1203 case SIL_FAULT_PKUERR: 1204 case SIL_PERF_EVENT: 1205 case SIL_SYS: 1206 ret = false; 1207 break; 1208 } 1209 return ret; 1210 } 1211 1212 static int send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t, 1213 enum pid_type type) 1214 { 1215 /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */ 1216 bool force = false; 1217 1218 if (info == SEND_SIG_NOINFO) { 1219 /* Force if sent from an ancestor pid namespace */ 1220 force = !task_pid_nr_ns(current, task_active_pid_ns(t)); 1221 } else if (info == SEND_SIG_PRIV) { 1222 /* Don't ignore kernel generated signals */ 1223 force = true; 1224 } else if (has_si_pid_and_uid(info)) { 1225 /* SIGKILL and SIGSTOP is special or has ids */ 1226 struct user_namespace *t_user_ns; 1227 1228 rcu_read_lock(); 1229 t_user_ns = task_cred_xxx(t, user_ns); 1230 if (current_user_ns() != t_user_ns) { 1231 kuid_t uid = make_kuid(current_user_ns(), info->si_uid); 1232 info->si_uid = from_kuid_munged(t_user_ns, uid); 1233 } 1234 rcu_read_unlock(); 1235 1236 /* A kernel generated signal? */ 1237 force = (info->si_code == SI_KERNEL); 1238 1239 /* From an ancestor pid namespace? */ 1240 if (!task_pid_nr_ns(current, task_active_pid_ns(t))) { 1241 info->si_pid = 0; 1242 force = true; 1243 } 1244 } 1245 return __send_signal(sig, info, t, type, force); 1246 } 1247 1248 static void print_fatal_signal(int signr) 1249 { 1250 struct pt_regs *regs = signal_pt_regs(); 1251 pr_info("potentially unexpected fatal signal %d.\n", signr); 1252 1253 #if defined(__i386__) && !defined(__arch_um__) 1254 pr_info("code at %08lx: ", regs->ip); 1255 { 1256 int i; 1257 for (i = 0; i < 16; i++) { 1258 unsigned char insn; 1259 1260 if (get_user(insn, (unsigned char *)(regs->ip + i))) 1261 break; 1262 pr_cont("%02x ", insn); 1263 } 1264 } 1265 pr_cont("\n"); 1266 #endif 1267 preempt_disable(); 1268 show_regs(regs); 1269 preempt_enable(); 1270 } 1271 1272 static int __init setup_print_fatal_signals(char *str) 1273 { 1274 get_option (&str, &print_fatal_signals); 1275 1276 return 1; 1277 } 1278 1279 __setup("print-fatal-signals=", setup_print_fatal_signals); 1280 1281 int 1282 __group_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p) 1283 { 1284 return send_signal(sig, info, p, PIDTYPE_TGID); 1285 } 1286 1287 int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p, 1288 enum pid_type type) 1289 { 1290 unsigned long flags; 1291 int ret = -ESRCH; 1292 1293 if (lock_task_sighand(p, &flags)) { 1294 ret = send_signal(sig, info, p, type); 1295 unlock_task_sighand(p, &flags); 1296 } 1297 1298 return ret; 1299 } 1300 1301 /* 1302 * Force a signal that the process can't ignore: if necessary 1303 * we unblock the signal and change any SIG_IGN to SIG_DFL. 1304 * 1305 * Note: If we unblock the signal, we always reset it to SIG_DFL, 1306 * since we do not want to have a signal handler that was blocked 1307 * be invoked when user space had explicitly blocked it. 1308 * 1309 * We don't want to have recursive SIGSEGV's etc, for example, 1310 * that is why we also clear SIGNAL_UNKILLABLE. 1311 */ 1312 static int 1313 force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t) 1314 { 1315 unsigned long int flags; 1316 int ret, blocked, ignored; 1317 struct k_sigaction *action; 1318 int sig = info->si_signo; 1319 1320 spin_lock_irqsave(&t->sighand->siglock, flags); 1321 action = &t->sighand->action[sig-1]; 1322 ignored = action->sa.sa_handler == SIG_IGN; 1323 blocked = sigismember(&t->blocked, sig); 1324 if (blocked || ignored) { 1325 action->sa.sa_handler = SIG_DFL; 1326 if (blocked) { 1327 sigdelset(&t->blocked, sig); 1328 recalc_sigpending_and_wake(t); 1329 } 1330 } 1331 /* 1332 * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect 1333 * debugging to leave init killable. 1334 */ 1335 if (action->sa.sa_handler == SIG_DFL && !t->ptrace) 1336 t->signal->flags &= ~SIGNAL_UNKILLABLE; 1337 ret = send_signal(sig, info, t, PIDTYPE_PID); 1338 spin_unlock_irqrestore(&t->sighand->siglock, flags); 1339 1340 return ret; 1341 } 1342 1343 int force_sig_info(struct kernel_siginfo *info) 1344 { 1345 return force_sig_info_to_task(info, current); 1346 } 1347 1348 /* 1349 * Nuke all other threads in the group. 1350 */ 1351 int zap_other_threads(struct task_struct *p) 1352 { 1353 struct task_struct *t = p; 1354 int count = 0; 1355 1356 p->signal->group_stop_count = 0; 1357 1358 while_each_thread(p, t) { 1359 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); 1360 count++; 1361 1362 /* Don't bother with already dead threads */ 1363 if (t->exit_state) 1364 continue; 1365 sigaddset(&t->pending.signal, SIGKILL); 1366 signal_wake_up(t, 1); 1367 } 1368 1369 return count; 1370 } 1371 1372 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk, 1373 unsigned long *flags) 1374 { 1375 struct sighand_struct *sighand; 1376 1377 rcu_read_lock(); 1378 for (;;) { 1379 sighand = rcu_dereference(tsk->sighand); 1380 if (unlikely(sighand == NULL)) 1381 break; 1382 1383 /* 1384 * This sighand can be already freed and even reused, but 1385 * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which 1386 * initializes ->siglock: this slab can't go away, it has 1387 * the same object type, ->siglock can't be reinitialized. 1388 * 1389 * We need to ensure that tsk->sighand is still the same 1390 * after we take the lock, we can race with de_thread() or 1391 * __exit_signal(). In the latter case the next iteration 1392 * must see ->sighand == NULL. 1393 */ 1394 spin_lock_irqsave(&sighand->siglock, *flags); 1395 if (likely(sighand == rcu_access_pointer(tsk->sighand))) 1396 break; 1397 spin_unlock_irqrestore(&sighand->siglock, *flags); 1398 } 1399 rcu_read_unlock(); 1400 1401 return sighand; 1402 } 1403 1404 /* 1405 * send signal info to all the members of a group 1406 */ 1407 int group_send_sig_info(int sig, struct kernel_siginfo *info, 1408 struct task_struct *p, enum pid_type type) 1409 { 1410 int ret; 1411 1412 rcu_read_lock(); 1413 ret = check_kill_permission(sig, info, p); 1414 rcu_read_unlock(); 1415 1416 if (!ret && sig) 1417 ret = do_send_sig_info(sig, info, p, type); 1418 1419 return ret; 1420 } 1421 1422 /* 1423 * __kill_pgrp_info() sends a signal to a process group: this is what the tty 1424 * control characters do (^C, ^Z etc) 1425 * - the caller must hold at least a readlock on tasklist_lock 1426 */ 1427 int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp) 1428 { 1429 struct task_struct *p = NULL; 1430 int retval, success; 1431 1432 success = 0; 1433 retval = -ESRCH; 1434 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 1435 int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID); 1436 success |= !err; 1437 retval = err; 1438 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 1439 return success ? 0 : retval; 1440 } 1441 1442 int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid) 1443 { 1444 int error = -ESRCH; 1445 struct task_struct *p; 1446 1447 for (;;) { 1448 rcu_read_lock(); 1449 p = pid_task(pid, PIDTYPE_PID); 1450 if (p) 1451 error = group_send_sig_info(sig, info, p, PIDTYPE_TGID); 1452 rcu_read_unlock(); 1453 if (likely(!p || error != -ESRCH)) 1454 return error; 1455 1456 /* 1457 * The task was unhashed in between, try again. If it 1458 * is dead, pid_task() will return NULL, if we race with 1459 * de_thread() it will find the new leader. 1460 */ 1461 } 1462 } 1463 1464 static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid) 1465 { 1466 int error; 1467 rcu_read_lock(); 1468 error = kill_pid_info(sig, info, find_vpid(pid)); 1469 rcu_read_unlock(); 1470 return error; 1471 } 1472 1473 static inline bool kill_as_cred_perm(const struct cred *cred, 1474 struct task_struct *target) 1475 { 1476 const struct cred *pcred = __task_cred(target); 1477 1478 return uid_eq(cred->euid, pcred->suid) || 1479 uid_eq(cred->euid, pcred->uid) || 1480 uid_eq(cred->uid, pcred->suid) || 1481 uid_eq(cred->uid, pcred->uid); 1482 } 1483 1484 /* 1485 * The usb asyncio usage of siginfo is wrong. The glibc support 1486 * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT. 1487 * AKA after the generic fields: 1488 * kernel_pid_t si_pid; 1489 * kernel_uid32_t si_uid; 1490 * sigval_t si_value; 1491 * 1492 * Unfortunately when usb generates SI_ASYNCIO it assumes the layout 1493 * after the generic fields is: 1494 * void __user *si_addr; 1495 * 1496 * This is a practical problem when there is a 64bit big endian kernel 1497 * and a 32bit userspace. As the 32bit address will encoded in the low 1498 * 32bits of the pointer. Those low 32bits will be stored at higher 1499 * address than appear in a 32 bit pointer. So userspace will not 1500 * see the address it was expecting for it's completions. 1501 * 1502 * There is nothing in the encoding that can allow 1503 * copy_siginfo_to_user32 to detect this confusion of formats, so 1504 * handle this by requiring the caller of kill_pid_usb_asyncio to 1505 * notice when this situration takes place and to store the 32bit 1506 * pointer in sival_int, instead of sival_addr of the sigval_t addr 1507 * parameter. 1508 */ 1509 int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr, 1510 struct pid *pid, const struct cred *cred) 1511 { 1512 struct kernel_siginfo info; 1513 struct task_struct *p; 1514 unsigned long flags; 1515 int ret = -EINVAL; 1516 1517 if (!valid_signal(sig)) 1518 return ret; 1519 1520 clear_siginfo(&info); 1521 info.si_signo = sig; 1522 info.si_errno = errno; 1523 info.si_code = SI_ASYNCIO; 1524 *((sigval_t *)&info.si_pid) = addr; 1525 1526 rcu_read_lock(); 1527 p = pid_task(pid, PIDTYPE_PID); 1528 if (!p) { 1529 ret = -ESRCH; 1530 goto out_unlock; 1531 } 1532 if (!kill_as_cred_perm(cred, p)) { 1533 ret = -EPERM; 1534 goto out_unlock; 1535 } 1536 ret = security_task_kill(p, &info, sig, cred); 1537 if (ret) 1538 goto out_unlock; 1539 1540 if (sig) { 1541 if (lock_task_sighand(p, &flags)) { 1542 ret = __send_signal(sig, &info, p, PIDTYPE_TGID, false); 1543 unlock_task_sighand(p, &flags); 1544 } else 1545 ret = -ESRCH; 1546 } 1547 out_unlock: 1548 rcu_read_unlock(); 1549 return ret; 1550 } 1551 EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio); 1552 1553 /* 1554 * kill_something_info() interprets pid in interesting ways just like kill(2). 1555 * 1556 * POSIX specifies that kill(-1,sig) is unspecified, but what we have 1557 * is probably wrong. Should make it like BSD or SYSV. 1558 */ 1559 1560 static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid) 1561 { 1562 int ret; 1563 1564 if (pid > 0) 1565 return kill_proc_info(sig, info, pid); 1566 1567 /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */ 1568 if (pid == INT_MIN) 1569 return -ESRCH; 1570 1571 read_lock(&tasklist_lock); 1572 if (pid != -1) { 1573 ret = __kill_pgrp_info(sig, info, 1574 pid ? find_vpid(-pid) : task_pgrp(current)); 1575 } else { 1576 int retval = 0, count = 0; 1577 struct task_struct * p; 1578 1579 for_each_process(p) { 1580 if (task_pid_vnr(p) > 1 && 1581 !same_thread_group(p, current)) { 1582 int err = group_send_sig_info(sig, info, p, 1583 PIDTYPE_MAX); 1584 ++count; 1585 if (err != -EPERM) 1586 retval = err; 1587 } 1588 } 1589 ret = count ? retval : -ESRCH; 1590 } 1591 read_unlock(&tasklist_lock); 1592 1593 return ret; 1594 } 1595 1596 /* 1597 * These are for backward compatibility with the rest of the kernel source. 1598 */ 1599 1600 int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p) 1601 { 1602 /* 1603 * Make sure legacy kernel users don't send in bad values 1604 * (normal paths check this in check_kill_permission). 1605 */ 1606 if (!valid_signal(sig)) 1607 return -EINVAL; 1608 1609 return do_send_sig_info(sig, info, p, PIDTYPE_PID); 1610 } 1611 EXPORT_SYMBOL(send_sig_info); 1612 1613 #define __si_special(priv) \ 1614 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO) 1615 1616 int 1617 send_sig(int sig, struct task_struct *p, int priv) 1618 { 1619 return send_sig_info(sig, __si_special(priv), p); 1620 } 1621 EXPORT_SYMBOL(send_sig); 1622 1623 void force_sig(int sig) 1624 { 1625 struct kernel_siginfo info; 1626 1627 clear_siginfo(&info); 1628 info.si_signo = sig; 1629 info.si_errno = 0; 1630 info.si_code = SI_KERNEL; 1631 info.si_pid = 0; 1632 info.si_uid = 0; 1633 force_sig_info(&info); 1634 } 1635 EXPORT_SYMBOL(force_sig); 1636 1637 /* 1638 * When things go south during signal handling, we 1639 * will force a SIGSEGV. And if the signal that caused 1640 * the problem was already a SIGSEGV, we'll want to 1641 * make sure we don't even try to deliver the signal.. 1642 */ 1643 void force_sigsegv(int sig) 1644 { 1645 struct task_struct *p = current; 1646 1647 if (sig == SIGSEGV) { 1648 unsigned long flags; 1649 spin_lock_irqsave(&p->sighand->siglock, flags); 1650 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL; 1651 spin_unlock_irqrestore(&p->sighand->siglock, flags); 1652 } 1653 force_sig(SIGSEGV); 1654 } 1655 1656 int force_sig_fault_to_task(int sig, int code, void __user *addr 1657 ___ARCH_SI_TRAPNO(int trapno) 1658 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr) 1659 , struct task_struct *t) 1660 { 1661 struct kernel_siginfo info; 1662 1663 clear_siginfo(&info); 1664 info.si_signo = sig; 1665 info.si_errno = 0; 1666 info.si_code = code; 1667 info.si_addr = addr; 1668 #ifdef __ARCH_SI_TRAPNO 1669 info.si_trapno = trapno; 1670 #endif 1671 #ifdef __ia64__ 1672 info.si_imm = imm; 1673 info.si_flags = flags; 1674 info.si_isr = isr; 1675 #endif 1676 return force_sig_info_to_task(&info, t); 1677 } 1678 1679 int force_sig_fault(int sig, int code, void __user *addr 1680 ___ARCH_SI_TRAPNO(int trapno) 1681 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)) 1682 { 1683 return force_sig_fault_to_task(sig, code, addr 1684 ___ARCH_SI_TRAPNO(trapno) 1685 ___ARCH_SI_IA64(imm, flags, isr), current); 1686 } 1687 1688 int send_sig_fault(int sig, int code, void __user *addr 1689 ___ARCH_SI_TRAPNO(int trapno) 1690 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr) 1691 , struct task_struct *t) 1692 { 1693 struct kernel_siginfo info; 1694 1695 clear_siginfo(&info); 1696 info.si_signo = sig; 1697 info.si_errno = 0; 1698 info.si_code = code; 1699 info.si_addr = addr; 1700 #ifdef __ARCH_SI_TRAPNO 1701 info.si_trapno = trapno; 1702 #endif 1703 #ifdef __ia64__ 1704 info.si_imm = imm; 1705 info.si_flags = flags; 1706 info.si_isr = isr; 1707 #endif 1708 return send_sig_info(info.si_signo, &info, t); 1709 } 1710 1711 int force_sig_mceerr(int code, void __user *addr, short lsb) 1712 { 1713 struct kernel_siginfo info; 1714 1715 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR)); 1716 clear_siginfo(&info); 1717 info.si_signo = SIGBUS; 1718 info.si_errno = 0; 1719 info.si_code = code; 1720 info.si_addr = addr; 1721 info.si_addr_lsb = lsb; 1722 return force_sig_info(&info); 1723 } 1724 1725 int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t) 1726 { 1727 struct kernel_siginfo info; 1728 1729 WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR)); 1730 clear_siginfo(&info); 1731 info.si_signo = SIGBUS; 1732 info.si_errno = 0; 1733 info.si_code = code; 1734 info.si_addr = addr; 1735 info.si_addr_lsb = lsb; 1736 return send_sig_info(info.si_signo, &info, t); 1737 } 1738 EXPORT_SYMBOL(send_sig_mceerr); 1739 1740 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper) 1741 { 1742 struct kernel_siginfo info; 1743 1744 clear_siginfo(&info); 1745 info.si_signo = SIGSEGV; 1746 info.si_errno = 0; 1747 info.si_code = SEGV_BNDERR; 1748 info.si_addr = addr; 1749 info.si_lower = lower; 1750 info.si_upper = upper; 1751 return force_sig_info(&info); 1752 } 1753 1754 #ifdef SEGV_PKUERR 1755 int force_sig_pkuerr(void __user *addr, u32 pkey) 1756 { 1757 struct kernel_siginfo info; 1758 1759 clear_siginfo(&info); 1760 info.si_signo = SIGSEGV; 1761 info.si_errno = 0; 1762 info.si_code = SEGV_PKUERR; 1763 info.si_addr = addr; 1764 info.si_pkey = pkey; 1765 return force_sig_info(&info); 1766 } 1767 #endif 1768 1769 int force_sig_perf(void __user *addr, u32 type, u64 sig_data) 1770 { 1771 struct kernel_siginfo info; 1772 1773 clear_siginfo(&info); 1774 info.si_signo = SIGTRAP; 1775 info.si_errno = 0; 1776 info.si_code = TRAP_PERF; 1777 info.si_addr = addr; 1778 info.si_perf_data = sig_data; 1779 info.si_perf_type = type; 1780 1781 return force_sig_info(&info); 1782 } 1783 1784 /* For the crazy architectures that include trap information in 1785 * the errno field, instead of an actual errno value. 1786 */ 1787 int force_sig_ptrace_errno_trap(int errno, void __user *addr) 1788 { 1789 struct kernel_siginfo info; 1790 1791 clear_siginfo(&info); 1792 info.si_signo = SIGTRAP; 1793 info.si_errno = errno; 1794 info.si_code = TRAP_HWBKPT; 1795 info.si_addr = addr; 1796 return force_sig_info(&info); 1797 } 1798 1799 int kill_pgrp(struct pid *pid, int sig, int priv) 1800 { 1801 int ret; 1802 1803 read_lock(&tasklist_lock); 1804 ret = __kill_pgrp_info(sig, __si_special(priv), pid); 1805 read_unlock(&tasklist_lock); 1806 1807 return ret; 1808 } 1809 EXPORT_SYMBOL(kill_pgrp); 1810 1811 int kill_pid(struct pid *pid, int sig, int priv) 1812 { 1813 return kill_pid_info(sig, __si_special(priv), pid); 1814 } 1815 EXPORT_SYMBOL(kill_pid); 1816 1817 /* 1818 * These functions support sending signals using preallocated sigqueue 1819 * structures. This is needed "because realtime applications cannot 1820 * afford to lose notifications of asynchronous events, like timer 1821 * expirations or I/O completions". In the case of POSIX Timers 1822 * we allocate the sigqueue structure from the timer_create. If this 1823 * allocation fails we are able to report the failure to the application 1824 * with an EAGAIN error. 1825 */ 1826 struct sigqueue *sigqueue_alloc(void) 1827 { 1828 return __sigqueue_alloc(-1, current, GFP_KERNEL, 0, SIGQUEUE_PREALLOC); 1829 } 1830 1831 void sigqueue_free(struct sigqueue *q) 1832 { 1833 unsigned long flags; 1834 spinlock_t *lock = ¤t->sighand->siglock; 1835 1836 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); 1837 /* 1838 * We must hold ->siglock while testing q->list 1839 * to serialize with collect_signal() or with 1840 * __exit_signal()->flush_sigqueue(). 1841 */ 1842 spin_lock_irqsave(lock, flags); 1843 q->flags &= ~SIGQUEUE_PREALLOC; 1844 /* 1845 * If it is queued it will be freed when dequeued, 1846 * like the "regular" sigqueue. 1847 */ 1848 if (!list_empty(&q->list)) 1849 q = NULL; 1850 spin_unlock_irqrestore(lock, flags); 1851 1852 if (q) 1853 __sigqueue_free(q); 1854 } 1855 1856 int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type) 1857 { 1858 int sig = q->info.si_signo; 1859 struct sigpending *pending; 1860 struct task_struct *t; 1861 unsigned long flags; 1862 int ret, result; 1863 1864 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); 1865 1866 ret = -1; 1867 rcu_read_lock(); 1868 t = pid_task(pid, type); 1869 if (!t || !likely(lock_task_sighand(t, &flags))) 1870 goto ret; 1871 1872 ret = 1; /* the signal is ignored */ 1873 result = TRACE_SIGNAL_IGNORED; 1874 if (!prepare_signal(sig, t, false)) 1875 goto out; 1876 1877 ret = 0; 1878 if (unlikely(!list_empty(&q->list))) { 1879 /* 1880 * If an SI_TIMER entry is already queue just increment 1881 * the overrun count. 1882 */ 1883 BUG_ON(q->info.si_code != SI_TIMER); 1884 q->info.si_overrun++; 1885 result = TRACE_SIGNAL_ALREADY_PENDING; 1886 goto out; 1887 } 1888 q->info.si_overrun = 0; 1889 1890 signalfd_notify(t, sig); 1891 pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending; 1892 list_add_tail(&q->list, &pending->list); 1893 sigaddset(&pending->signal, sig); 1894 complete_signal(sig, t, type); 1895 result = TRACE_SIGNAL_DELIVERED; 1896 out: 1897 trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result); 1898 unlock_task_sighand(t, &flags); 1899 ret: 1900 rcu_read_unlock(); 1901 return ret; 1902 } 1903 1904 static void do_notify_pidfd(struct task_struct *task) 1905 { 1906 struct pid *pid; 1907 1908 WARN_ON(task->exit_state == 0); 1909 pid = task_pid(task); 1910 wake_up_all(&pid->wait_pidfd); 1911 } 1912 1913 /* 1914 * Let a parent know about the death of a child. 1915 * For a stopped/continued status change, use do_notify_parent_cldstop instead. 1916 * 1917 * Returns true if our parent ignored us and so we've switched to 1918 * self-reaping. 1919 */ 1920 bool do_notify_parent(struct task_struct *tsk, int sig) 1921 { 1922 struct kernel_siginfo info; 1923 unsigned long flags; 1924 struct sighand_struct *psig; 1925 bool autoreap = false; 1926 u64 utime, stime; 1927 1928 BUG_ON(sig == -1); 1929 1930 /* do_notify_parent_cldstop should have been called instead. */ 1931 BUG_ON(task_is_stopped_or_traced(tsk)); 1932 1933 BUG_ON(!tsk->ptrace && 1934 (tsk->group_leader != tsk || !thread_group_empty(tsk))); 1935 1936 /* Wake up all pidfd waiters */ 1937 do_notify_pidfd(tsk); 1938 1939 if (sig != SIGCHLD) { 1940 /* 1941 * This is only possible if parent == real_parent. 1942 * Check if it has changed security domain. 1943 */ 1944 if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id)) 1945 sig = SIGCHLD; 1946 } 1947 1948 clear_siginfo(&info); 1949 info.si_signo = sig; 1950 info.si_errno = 0; 1951 /* 1952 * We are under tasklist_lock here so our parent is tied to 1953 * us and cannot change. 1954 * 1955 * task_active_pid_ns will always return the same pid namespace 1956 * until a task passes through release_task. 1957 * 1958 * write_lock() currently calls preempt_disable() which is the 1959 * same as rcu_read_lock(), but according to Oleg, this is not 1960 * correct to rely on this 1961 */ 1962 rcu_read_lock(); 1963 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent)); 1964 info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns), 1965 task_uid(tsk)); 1966 rcu_read_unlock(); 1967 1968 task_cputime(tsk, &utime, &stime); 1969 info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime); 1970 info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime); 1971 1972 info.si_status = tsk->exit_code & 0x7f; 1973 if (tsk->exit_code & 0x80) 1974 info.si_code = CLD_DUMPED; 1975 else if (tsk->exit_code & 0x7f) 1976 info.si_code = CLD_KILLED; 1977 else { 1978 info.si_code = CLD_EXITED; 1979 info.si_status = tsk->exit_code >> 8; 1980 } 1981 1982 psig = tsk->parent->sighand; 1983 spin_lock_irqsave(&psig->siglock, flags); 1984 if (!tsk->ptrace && sig == SIGCHLD && 1985 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN || 1986 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) { 1987 /* 1988 * We are exiting and our parent doesn't care. POSIX.1 1989 * defines special semantics for setting SIGCHLD to SIG_IGN 1990 * or setting the SA_NOCLDWAIT flag: we should be reaped 1991 * automatically and not left for our parent's wait4 call. 1992 * Rather than having the parent do it as a magic kind of 1993 * signal handler, we just set this to tell do_exit that we 1994 * can be cleaned up without becoming a zombie. Note that 1995 * we still call __wake_up_parent in this case, because a 1996 * blocked sys_wait4 might now return -ECHILD. 1997 * 1998 * Whether we send SIGCHLD or not for SA_NOCLDWAIT 1999 * is implementation-defined: we do (if you don't want 2000 * it, just use SIG_IGN instead). 2001 */ 2002 autoreap = true; 2003 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) 2004 sig = 0; 2005 } 2006 /* 2007 * Send with __send_signal as si_pid and si_uid are in the 2008 * parent's namespaces. 2009 */ 2010 if (valid_signal(sig) && sig) 2011 __send_signal(sig, &info, tsk->parent, PIDTYPE_TGID, false); 2012 __wake_up_parent(tsk, tsk->parent); 2013 spin_unlock_irqrestore(&psig->siglock, flags); 2014 2015 return autoreap; 2016 } 2017 2018 /** 2019 * do_notify_parent_cldstop - notify parent of stopped/continued state change 2020 * @tsk: task reporting the state change 2021 * @for_ptracer: the notification is for ptracer 2022 * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report 2023 * 2024 * Notify @tsk's parent that the stopped/continued state has changed. If 2025 * @for_ptracer is %false, @tsk's group leader notifies to its real parent. 2026 * If %true, @tsk reports to @tsk->parent which should be the ptracer. 2027 * 2028 * CONTEXT: 2029 * Must be called with tasklist_lock at least read locked. 2030 */ 2031 static void do_notify_parent_cldstop(struct task_struct *tsk, 2032 bool for_ptracer, int why) 2033 { 2034 struct kernel_siginfo info; 2035 unsigned long flags; 2036 struct task_struct *parent; 2037 struct sighand_struct *sighand; 2038 u64 utime, stime; 2039 2040 if (for_ptracer) { 2041 parent = tsk->parent; 2042 } else { 2043 tsk = tsk->group_leader; 2044 parent = tsk->real_parent; 2045 } 2046 2047 clear_siginfo(&info); 2048 info.si_signo = SIGCHLD; 2049 info.si_errno = 0; 2050 /* 2051 * see comment in do_notify_parent() about the following 4 lines 2052 */ 2053 rcu_read_lock(); 2054 info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent)); 2055 info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk)); 2056 rcu_read_unlock(); 2057 2058 task_cputime(tsk, &utime, &stime); 2059 info.si_utime = nsec_to_clock_t(utime); 2060 info.si_stime = nsec_to_clock_t(stime); 2061 2062 info.si_code = why; 2063 switch (why) { 2064 case CLD_CONTINUED: 2065 info.si_status = SIGCONT; 2066 break; 2067 case CLD_STOPPED: 2068 info.si_status = tsk->signal->group_exit_code & 0x7f; 2069 break; 2070 case CLD_TRAPPED: 2071 info.si_status = tsk->exit_code & 0x7f; 2072 break; 2073 default: 2074 BUG(); 2075 } 2076 2077 sighand = parent->sighand; 2078 spin_lock_irqsave(&sighand->siglock, flags); 2079 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN && 2080 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP)) 2081 __group_send_sig_info(SIGCHLD, &info, parent); 2082 /* 2083 * Even if SIGCHLD is not generated, we must wake up wait4 calls. 2084 */ 2085 __wake_up_parent(tsk, parent); 2086 spin_unlock_irqrestore(&sighand->siglock, flags); 2087 } 2088 2089 static inline bool may_ptrace_stop(void) 2090 { 2091 if (!likely(current->ptrace)) 2092 return false; 2093 /* 2094 * Are we in the middle of do_coredump? 2095 * If so and our tracer is also part of the coredump stopping 2096 * is a deadlock situation, and pointless because our tracer 2097 * is dead so don't allow us to stop. 2098 * If SIGKILL was already sent before the caller unlocked 2099 * ->siglock we must see ->core_state != NULL. Otherwise it 2100 * is safe to enter schedule(). 2101 * 2102 * This is almost outdated, a task with the pending SIGKILL can't 2103 * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported 2104 * after SIGKILL was already dequeued. 2105 */ 2106 if (unlikely(current->mm->core_state) && 2107 unlikely(current->mm == current->parent->mm)) 2108 return false; 2109 2110 return true; 2111 } 2112 2113 /* 2114 * Return non-zero if there is a SIGKILL that should be waking us up. 2115 * Called with the siglock held. 2116 */ 2117 static bool sigkill_pending(struct task_struct *tsk) 2118 { 2119 return sigismember(&tsk->pending.signal, SIGKILL) || 2120 sigismember(&tsk->signal->shared_pending.signal, SIGKILL); 2121 } 2122 2123 /* 2124 * This must be called with current->sighand->siglock held. 2125 * 2126 * This should be the path for all ptrace stops. 2127 * We always set current->last_siginfo while stopped here. 2128 * That makes it a way to test a stopped process for 2129 * being ptrace-stopped vs being job-control-stopped. 2130 * 2131 * If we actually decide not to stop at all because the tracer 2132 * is gone, we keep current->exit_code unless clear_code. 2133 */ 2134 static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t *info) 2135 __releases(¤t->sighand->siglock) 2136 __acquires(¤t->sighand->siglock) 2137 { 2138 bool gstop_done = false; 2139 2140 if (arch_ptrace_stop_needed(exit_code, info)) { 2141 /* 2142 * The arch code has something special to do before a 2143 * ptrace stop. This is allowed to block, e.g. for faults 2144 * on user stack pages. We can't keep the siglock while 2145 * calling arch_ptrace_stop, so we must release it now. 2146 * To preserve proper semantics, we must do this before 2147 * any signal bookkeeping like checking group_stop_count. 2148 * Meanwhile, a SIGKILL could come in before we retake the 2149 * siglock. That must prevent us from sleeping in TASK_TRACED. 2150 * So after regaining the lock, we must check for SIGKILL. 2151 */ 2152 spin_unlock_irq(¤t->sighand->siglock); 2153 arch_ptrace_stop(exit_code, info); 2154 spin_lock_irq(¤t->sighand->siglock); 2155 if (sigkill_pending(current)) 2156 return; 2157 } 2158 2159 set_special_state(TASK_TRACED); 2160 2161 /* 2162 * We're committing to trapping. TRACED should be visible before 2163 * TRAPPING is cleared; otherwise, the tracer might fail do_wait(). 2164 * Also, transition to TRACED and updates to ->jobctl should be 2165 * atomic with respect to siglock and should be done after the arch 2166 * hook as siglock is released and regrabbed across it. 2167 * 2168 * TRACER TRACEE 2169 * 2170 * ptrace_attach() 2171 * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED) 2172 * do_wait() 2173 * set_current_state() smp_wmb(); 2174 * ptrace_do_wait() 2175 * wait_task_stopped() 2176 * task_stopped_code() 2177 * [L] task_is_traced() [S] task_clear_jobctl_trapping(); 2178 */ 2179 smp_wmb(); 2180 2181 current->last_siginfo = info; 2182 current->exit_code = exit_code; 2183 2184 /* 2185 * If @why is CLD_STOPPED, we're trapping to participate in a group 2186 * stop. Do the bookkeeping. Note that if SIGCONT was delievered 2187 * across siglock relocks since INTERRUPT was scheduled, PENDING 2188 * could be clear now. We act as if SIGCONT is received after 2189 * TASK_TRACED is entered - ignore it. 2190 */ 2191 if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING)) 2192 gstop_done = task_participate_group_stop(current); 2193 2194 /* any trap clears pending STOP trap, STOP trap clears NOTIFY */ 2195 task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP); 2196 if (info && info->si_code >> 8 == PTRACE_EVENT_STOP) 2197 task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY); 2198 2199 /* entering a trap, clear TRAPPING */ 2200 task_clear_jobctl_trapping(current); 2201 2202 spin_unlock_irq(¤t->sighand->siglock); 2203 read_lock(&tasklist_lock); 2204 if (may_ptrace_stop()) { 2205 /* 2206 * Notify parents of the stop. 2207 * 2208 * While ptraced, there are two parents - the ptracer and 2209 * the real_parent of the group_leader. The ptracer should 2210 * know about every stop while the real parent is only 2211 * interested in the completion of group stop. The states 2212 * for the two don't interact with each other. Notify 2213 * separately unless they're gonna be duplicates. 2214 */ 2215 do_notify_parent_cldstop(current, true, why); 2216 if (gstop_done && ptrace_reparented(current)) 2217 do_notify_parent_cldstop(current, false, why); 2218 2219 /* 2220 * Don't want to allow preemption here, because 2221 * sys_ptrace() needs this task to be inactive. 2222 * 2223 * XXX: implement read_unlock_no_resched(). 2224 */ 2225 preempt_disable(); 2226 read_unlock(&tasklist_lock); 2227 cgroup_enter_frozen(); 2228 preempt_enable_no_resched(); 2229 freezable_schedule(); 2230 cgroup_leave_frozen(true); 2231 } else { 2232 /* 2233 * By the time we got the lock, our tracer went away. 2234 * Don't drop the lock yet, another tracer may come. 2235 * 2236 * If @gstop_done, the ptracer went away between group stop 2237 * completion and here. During detach, it would have set 2238 * JOBCTL_STOP_PENDING on us and we'll re-enter 2239 * TASK_STOPPED in do_signal_stop() on return, so notifying 2240 * the real parent of the group stop completion is enough. 2241 */ 2242 if (gstop_done) 2243 do_notify_parent_cldstop(current, false, why); 2244 2245 /* tasklist protects us from ptrace_freeze_traced() */ 2246 __set_current_state(TASK_RUNNING); 2247 if (clear_code) 2248 current->exit_code = 0; 2249 read_unlock(&tasklist_lock); 2250 } 2251 2252 /* 2253 * We are back. Now reacquire the siglock before touching 2254 * last_siginfo, so that we are sure to have synchronized with 2255 * any signal-sending on another CPU that wants to examine it. 2256 */ 2257 spin_lock_irq(¤t->sighand->siglock); 2258 current->last_siginfo = NULL; 2259 2260 /* LISTENING can be set only during STOP traps, clear it */ 2261 current->jobctl &= ~JOBCTL_LISTENING; 2262 2263 /* 2264 * Queued signals ignored us while we were stopped for tracing. 2265 * So check for any that we should take before resuming user mode. 2266 * This sets TIF_SIGPENDING, but never clears it. 2267 */ 2268 recalc_sigpending_tsk(current); 2269 } 2270 2271 static void ptrace_do_notify(int signr, int exit_code, int why) 2272 { 2273 kernel_siginfo_t info; 2274 2275 clear_siginfo(&info); 2276 info.si_signo = signr; 2277 info.si_code = exit_code; 2278 info.si_pid = task_pid_vnr(current); 2279 info.si_uid = from_kuid_munged(current_user_ns(), current_uid()); 2280 2281 /* Let the debugger run. */ 2282 ptrace_stop(exit_code, why, 1, &info); 2283 } 2284 2285 void ptrace_notify(int exit_code) 2286 { 2287 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP); 2288 if (unlikely(current->task_works)) 2289 task_work_run(); 2290 2291 spin_lock_irq(¤t->sighand->siglock); 2292 ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED); 2293 spin_unlock_irq(¤t->sighand->siglock); 2294 } 2295 2296 /** 2297 * do_signal_stop - handle group stop for SIGSTOP and other stop signals 2298 * @signr: signr causing group stop if initiating 2299 * 2300 * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr 2301 * and participate in it. If already set, participate in the existing 2302 * group stop. If participated in a group stop (and thus slept), %true is 2303 * returned with siglock released. 2304 * 2305 * If ptraced, this function doesn't handle stop itself. Instead, 2306 * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock 2307 * untouched. The caller must ensure that INTERRUPT trap handling takes 2308 * places afterwards. 2309 * 2310 * CONTEXT: 2311 * Must be called with @current->sighand->siglock held, which is released 2312 * on %true return. 2313 * 2314 * RETURNS: 2315 * %false if group stop is already cancelled or ptrace trap is scheduled. 2316 * %true if participated in group stop. 2317 */ 2318 static bool do_signal_stop(int signr) 2319 __releases(¤t->sighand->siglock) 2320 { 2321 struct signal_struct *sig = current->signal; 2322 2323 if (!(current->jobctl & JOBCTL_STOP_PENDING)) { 2324 unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME; 2325 struct task_struct *t; 2326 2327 /* signr will be recorded in task->jobctl for retries */ 2328 WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK); 2329 2330 if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) || 2331 unlikely(signal_group_exit(sig))) 2332 return false; 2333 /* 2334 * There is no group stop already in progress. We must 2335 * initiate one now. 2336 * 2337 * While ptraced, a task may be resumed while group stop is 2338 * still in effect and then receive a stop signal and 2339 * initiate another group stop. This deviates from the 2340 * usual behavior as two consecutive stop signals can't 2341 * cause two group stops when !ptraced. That is why we 2342 * also check !task_is_stopped(t) below. 2343 * 2344 * The condition can be distinguished by testing whether 2345 * SIGNAL_STOP_STOPPED is already set. Don't generate 2346 * group_exit_code in such case. 2347 * 2348 * This is not necessary for SIGNAL_STOP_CONTINUED because 2349 * an intervening stop signal is required to cause two 2350 * continued events regardless of ptrace. 2351 */ 2352 if (!(sig->flags & SIGNAL_STOP_STOPPED)) 2353 sig->group_exit_code = signr; 2354 2355 sig->group_stop_count = 0; 2356 2357 if (task_set_jobctl_pending(current, signr | gstop)) 2358 sig->group_stop_count++; 2359 2360 t = current; 2361 while_each_thread(current, t) { 2362 /* 2363 * Setting state to TASK_STOPPED for a group 2364 * stop is always done with the siglock held, 2365 * so this check has no races. 2366 */ 2367 if (!task_is_stopped(t) && 2368 task_set_jobctl_pending(t, signr | gstop)) { 2369 sig->group_stop_count++; 2370 if (likely(!(t->ptrace & PT_SEIZED))) 2371 signal_wake_up(t, 0); 2372 else 2373 ptrace_trap_notify(t); 2374 } 2375 } 2376 } 2377 2378 if (likely(!current->ptrace)) { 2379 int notify = 0; 2380 2381 /* 2382 * If there are no other threads in the group, or if there 2383 * is a group stop in progress and we are the last to stop, 2384 * report to the parent. 2385 */ 2386 if (task_participate_group_stop(current)) 2387 notify = CLD_STOPPED; 2388 2389 set_special_state(TASK_STOPPED); 2390 spin_unlock_irq(¤t->sighand->siglock); 2391 2392 /* 2393 * Notify the parent of the group stop completion. Because 2394 * we're not holding either the siglock or tasklist_lock 2395 * here, ptracer may attach inbetween; however, this is for 2396 * group stop and should always be delivered to the real 2397 * parent of the group leader. The new ptracer will get 2398 * its notification when this task transitions into 2399 * TASK_TRACED. 2400 */ 2401 if (notify) { 2402 read_lock(&tasklist_lock); 2403 do_notify_parent_cldstop(current, false, notify); 2404 read_unlock(&tasklist_lock); 2405 } 2406 2407 /* Now we don't run again until woken by SIGCONT or SIGKILL */ 2408 cgroup_enter_frozen(); 2409 freezable_schedule(); 2410 return true; 2411 } else { 2412 /* 2413 * While ptraced, group stop is handled by STOP trap. 2414 * Schedule it and let the caller deal with it. 2415 */ 2416 task_set_jobctl_pending(current, JOBCTL_TRAP_STOP); 2417 return false; 2418 } 2419 } 2420 2421 /** 2422 * do_jobctl_trap - take care of ptrace jobctl traps 2423 * 2424 * When PT_SEIZED, it's used for both group stop and explicit 2425 * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with 2426 * accompanying siginfo. If stopped, lower eight bits of exit_code contain 2427 * the stop signal; otherwise, %SIGTRAP. 2428 * 2429 * When !PT_SEIZED, it's used only for group stop trap with stop signal 2430 * number as exit_code and no siginfo. 2431 * 2432 * CONTEXT: 2433 * Must be called with @current->sighand->siglock held, which may be 2434 * released and re-acquired before returning with intervening sleep. 2435 */ 2436 static void do_jobctl_trap(void) 2437 { 2438 struct signal_struct *signal = current->signal; 2439 int signr = current->jobctl & JOBCTL_STOP_SIGMASK; 2440 2441 if (current->ptrace & PT_SEIZED) { 2442 if (!signal->group_stop_count && 2443 !(signal->flags & SIGNAL_STOP_STOPPED)) 2444 signr = SIGTRAP; 2445 WARN_ON_ONCE(!signr); 2446 ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8), 2447 CLD_STOPPED); 2448 } else { 2449 WARN_ON_ONCE(!signr); 2450 ptrace_stop(signr, CLD_STOPPED, 0, NULL); 2451 current->exit_code = 0; 2452 } 2453 } 2454 2455 /** 2456 * do_freezer_trap - handle the freezer jobctl trap 2457 * 2458 * Puts the task into frozen state, if only the task is not about to quit. 2459 * In this case it drops JOBCTL_TRAP_FREEZE. 2460 * 2461 * CONTEXT: 2462 * Must be called with @current->sighand->siglock held, 2463 * which is always released before returning. 2464 */ 2465 static void do_freezer_trap(void) 2466 __releases(¤t->sighand->siglock) 2467 { 2468 /* 2469 * If there are other trap bits pending except JOBCTL_TRAP_FREEZE, 2470 * let's make another loop to give it a chance to be handled. 2471 * In any case, we'll return back. 2472 */ 2473 if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) != 2474 JOBCTL_TRAP_FREEZE) { 2475 spin_unlock_irq(¤t->sighand->siglock); 2476 return; 2477 } 2478 2479 /* 2480 * Now we're sure that there is no pending fatal signal and no 2481 * pending traps. Clear TIF_SIGPENDING to not get out of schedule() 2482 * immediately (if there is a non-fatal signal pending), and 2483 * put the task into sleep. 2484 */ 2485 __set_current_state(TASK_INTERRUPTIBLE); 2486 clear_thread_flag(TIF_SIGPENDING); 2487 spin_unlock_irq(¤t->sighand->siglock); 2488 cgroup_enter_frozen(); 2489 freezable_schedule(); 2490 } 2491 2492 static int ptrace_signal(int signr, kernel_siginfo_t *info) 2493 { 2494 /* 2495 * We do not check sig_kernel_stop(signr) but set this marker 2496 * unconditionally because we do not know whether debugger will 2497 * change signr. This flag has no meaning unless we are going 2498 * to stop after return from ptrace_stop(). In this case it will 2499 * be checked in do_signal_stop(), we should only stop if it was 2500 * not cleared by SIGCONT while we were sleeping. See also the 2501 * comment in dequeue_signal(). 2502 */ 2503 current->jobctl |= JOBCTL_STOP_DEQUEUED; 2504 ptrace_stop(signr, CLD_TRAPPED, 0, info); 2505 2506 /* We're back. Did the debugger cancel the sig? */ 2507 signr = current->exit_code; 2508 if (signr == 0) 2509 return signr; 2510 2511 current->exit_code = 0; 2512 2513 /* 2514 * Update the siginfo structure if the signal has 2515 * changed. If the debugger wanted something 2516 * specific in the siginfo structure then it should 2517 * have updated *info via PTRACE_SETSIGINFO. 2518 */ 2519 if (signr != info->si_signo) { 2520 clear_siginfo(info); 2521 info->si_signo = signr; 2522 info->si_errno = 0; 2523 info->si_code = SI_USER; 2524 rcu_read_lock(); 2525 info->si_pid = task_pid_vnr(current->parent); 2526 info->si_uid = from_kuid_munged(current_user_ns(), 2527 task_uid(current->parent)); 2528 rcu_read_unlock(); 2529 } 2530 2531 /* If the (new) signal is now blocked, requeue it. */ 2532 if (sigismember(¤t->blocked, signr)) { 2533 send_signal(signr, info, current, PIDTYPE_PID); 2534 signr = 0; 2535 } 2536 2537 return signr; 2538 } 2539 2540 static void hide_si_addr_tag_bits(struct ksignal *ksig) 2541 { 2542 switch (siginfo_layout(ksig->sig, ksig->info.si_code)) { 2543 case SIL_FAULT: 2544 case SIL_FAULT_TRAPNO: 2545 case SIL_FAULT_MCEERR: 2546 case SIL_FAULT_BNDERR: 2547 case SIL_FAULT_PKUERR: 2548 case SIL_PERF_EVENT: 2549 ksig->info.si_addr = arch_untagged_si_addr( 2550 ksig->info.si_addr, ksig->sig, ksig->info.si_code); 2551 break; 2552 case SIL_KILL: 2553 case SIL_TIMER: 2554 case SIL_POLL: 2555 case SIL_CHLD: 2556 case SIL_RT: 2557 case SIL_SYS: 2558 break; 2559 } 2560 } 2561 2562 bool get_signal(struct ksignal *ksig) 2563 { 2564 struct sighand_struct *sighand = current->sighand; 2565 struct signal_struct *signal = current->signal; 2566 int signr; 2567 2568 if (unlikely(current->task_works)) 2569 task_work_run(); 2570 2571 /* 2572 * For non-generic architectures, check for TIF_NOTIFY_SIGNAL so 2573 * that the arch handlers don't all have to do it. If we get here 2574 * without TIF_SIGPENDING, just exit after running signal work. 2575 */ 2576 if (!IS_ENABLED(CONFIG_GENERIC_ENTRY)) { 2577 if (test_thread_flag(TIF_NOTIFY_SIGNAL)) 2578 tracehook_notify_signal(); 2579 if (!task_sigpending(current)) 2580 return false; 2581 } 2582 2583 if (unlikely(uprobe_deny_signal())) 2584 return false; 2585 2586 /* 2587 * Do this once, we can't return to user-mode if freezing() == T. 2588 * do_signal_stop() and ptrace_stop() do freezable_schedule() and 2589 * thus do not need another check after return. 2590 */ 2591 try_to_freeze(); 2592 2593 relock: 2594 spin_lock_irq(&sighand->siglock); 2595 2596 /* 2597 * Every stopped thread goes here after wakeup. Check to see if 2598 * we should notify the parent, prepare_signal(SIGCONT) encodes 2599 * the CLD_ si_code into SIGNAL_CLD_MASK bits. 2600 */ 2601 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) { 2602 int why; 2603 2604 if (signal->flags & SIGNAL_CLD_CONTINUED) 2605 why = CLD_CONTINUED; 2606 else 2607 why = CLD_STOPPED; 2608 2609 signal->flags &= ~SIGNAL_CLD_MASK; 2610 2611 spin_unlock_irq(&sighand->siglock); 2612 2613 /* 2614 * Notify the parent that we're continuing. This event is 2615 * always per-process and doesn't make whole lot of sense 2616 * for ptracers, who shouldn't consume the state via 2617 * wait(2) either, but, for backward compatibility, notify 2618 * the ptracer of the group leader too unless it's gonna be 2619 * a duplicate. 2620 */ 2621 read_lock(&tasklist_lock); 2622 do_notify_parent_cldstop(current, false, why); 2623 2624 if (ptrace_reparented(current->group_leader)) 2625 do_notify_parent_cldstop(current->group_leader, 2626 true, why); 2627 read_unlock(&tasklist_lock); 2628 2629 goto relock; 2630 } 2631 2632 /* Has this task already been marked for death? */ 2633 if (signal_group_exit(signal)) { 2634 ksig->info.si_signo = signr = SIGKILL; 2635 sigdelset(¤t->pending.signal, SIGKILL); 2636 trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO, 2637 &sighand->action[SIGKILL - 1]); 2638 recalc_sigpending(); 2639 goto fatal; 2640 } 2641 2642 for (;;) { 2643 struct k_sigaction *ka; 2644 2645 if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) && 2646 do_signal_stop(0)) 2647 goto relock; 2648 2649 if (unlikely(current->jobctl & 2650 (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) { 2651 if (current->jobctl & JOBCTL_TRAP_MASK) { 2652 do_jobctl_trap(); 2653 spin_unlock_irq(&sighand->siglock); 2654 } else if (current->jobctl & JOBCTL_TRAP_FREEZE) 2655 do_freezer_trap(); 2656 2657 goto relock; 2658 } 2659 2660 /* 2661 * If the task is leaving the frozen state, let's update 2662 * cgroup counters and reset the frozen bit. 2663 */ 2664 if (unlikely(cgroup_task_frozen(current))) { 2665 spin_unlock_irq(&sighand->siglock); 2666 cgroup_leave_frozen(false); 2667 goto relock; 2668 } 2669 2670 /* 2671 * Signals generated by the execution of an instruction 2672 * need to be delivered before any other pending signals 2673 * so that the instruction pointer in the signal stack 2674 * frame points to the faulting instruction. 2675 */ 2676 signr = dequeue_synchronous_signal(&ksig->info); 2677 if (!signr) 2678 signr = dequeue_signal(current, ¤t->blocked, &ksig->info); 2679 2680 if (!signr) 2681 break; /* will return 0 */ 2682 2683 if (unlikely(current->ptrace) && signr != SIGKILL) { 2684 signr = ptrace_signal(signr, &ksig->info); 2685 if (!signr) 2686 continue; 2687 } 2688 2689 ka = &sighand->action[signr-1]; 2690 2691 /* Trace actually delivered signals. */ 2692 trace_signal_deliver(signr, &ksig->info, ka); 2693 2694 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */ 2695 continue; 2696 if (ka->sa.sa_handler != SIG_DFL) { 2697 /* Run the handler. */ 2698 ksig->ka = *ka; 2699 2700 if (ka->sa.sa_flags & SA_ONESHOT) 2701 ka->sa.sa_handler = SIG_DFL; 2702 2703 break; /* will return non-zero "signr" value */ 2704 } 2705 2706 /* 2707 * Now we are doing the default action for this signal. 2708 */ 2709 if (sig_kernel_ignore(signr)) /* Default is nothing. */ 2710 continue; 2711 2712 /* 2713 * Global init gets no signals it doesn't want. 2714 * Container-init gets no signals it doesn't want from same 2715 * container. 2716 * 2717 * Note that if global/container-init sees a sig_kernel_only() 2718 * signal here, the signal must have been generated internally 2719 * or must have come from an ancestor namespace. In either 2720 * case, the signal cannot be dropped. 2721 */ 2722 if (unlikely(signal->flags & SIGNAL_UNKILLABLE) && 2723 !sig_kernel_only(signr)) 2724 continue; 2725 2726 if (sig_kernel_stop(signr)) { 2727 /* 2728 * The default action is to stop all threads in 2729 * the thread group. The job control signals 2730 * do nothing in an orphaned pgrp, but SIGSTOP 2731 * always works. Note that siglock needs to be 2732 * dropped during the call to is_orphaned_pgrp() 2733 * because of lock ordering with tasklist_lock. 2734 * This allows an intervening SIGCONT to be posted. 2735 * We need to check for that and bail out if necessary. 2736 */ 2737 if (signr != SIGSTOP) { 2738 spin_unlock_irq(&sighand->siglock); 2739 2740 /* signals can be posted during this window */ 2741 2742 if (is_current_pgrp_orphaned()) 2743 goto relock; 2744 2745 spin_lock_irq(&sighand->siglock); 2746 } 2747 2748 if (likely(do_signal_stop(ksig->info.si_signo))) { 2749 /* It released the siglock. */ 2750 goto relock; 2751 } 2752 2753 /* 2754 * We didn't actually stop, due to a race 2755 * with SIGCONT or something like that. 2756 */ 2757 continue; 2758 } 2759 2760 fatal: 2761 spin_unlock_irq(&sighand->siglock); 2762 if (unlikely(cgroup_task_frozen(current))) 2763 cgroup_leave_frozen(true); 2764 2765 /* 2766 * Anything else is fatal, maybe with a core dump. 2767 */ 2768 current->flags |= PF_SIGNALED; 2769 2770 if (sig_kernel_coredump(signr)) { 2771 if (print_fatal_signals) 2772 print_fatal_signal(ksig->info.si_signo); 2773 proc_coredump_connector(current); 2774 /* 2775 * If it was able to dump core, this kills all 2776 * other threads in the group and synchronizes with 2777 * their demise. If we lost the race with another 2778 * thread getting here, it set group_exit_code 2779 * first and our do_group_exit call below will use 2780 * that value and ignore the one we pass it. 2781 */ 2782 do_coredump(&ksig->info); 2783 } 2784 2785 /* 2786 * PF_IO_WORKER threads will catch and exit on fatal signals 2787 * themselves. They have cleanup that must be performed, so 2788 * we cannot call do_exit() on their behalf. 2789 */ 2790 if (current->flags & PF_IO_WORKER) 2791 goto out; 2792 2793 /* 2794 * Death signals, no core dump. 2795 */ 2796 do_group_exit(ksig->info.si_signo); 2797 /* NOTREACHED */ 2798 } 2799 spin_unlock_irq(&sighand->siglock); 2800 out: 2801 ksig->sig = signr; 2802 2803 if (!(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS)) 2804 hide_si_addr_tag_bits(ksig); 2805 2806 return ksig->sig > 0; 2807 } 2808 2809 /** 2810 * signal_delivered - 2811 * @ksig: kernel signal struct 2812 * @stepping: nonzero if debugger single-step or block-step in use 2813 * 2814 * This function should be called when a signal has successfully been 2815 * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask 2816 * is always blocked, and the signal itself is blocked unless %SA_NODEFER 2817 * is set in @ksig->ka.sa.sa_flags. Tracing is notified. 2818 */ 2819 static void signal_delivered(struct ksignal *ksig, int stepping) 2820 { 2821 sigset_t blocked; 2822 2823 /* A signal was successfully delivered, and the 2824 saved sigmask was stored on the signal frame, 2825 and will be restored by sigreturn. So we can 2826 simply clear the restore sigmask flag. */ 2827 clear_restore_sigmask(); 2828 2829 sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask); 2830 if (!(ksig->ka.sa.sa_flags & SA_NODEFER)) 2831 sigaddset(&blocked, ksig->sig); 2832 set_current_blocked(&blocked); 2833 if (current->sas_ss_flags & SS_AUTODISARM) 2834 sas_ss_reset(current); 2835 tracehook_signal_handler(stepping); 2836 } 2837 2838 void signal_setup_done(int failed, struct ksignal *ksig, int stepping) 2839 { 2840 if (failed) 2841 force_sigsegv(ksig->sig); 2842 else 2843 signal_delivered(ksig, stepping); 2844 } 2845 2846 /* 2847 * It could be that complete_signal() picked us to notify about the 2848 * group-wide signal. Other threads should be notified now to take 2849 * the shared signals in @which since we will not. 2850 */ 2851 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which) 2852 { 2853 sigset_t retarget; 2854 struct task_struct *t; 2855 2856 sigandsets(&retarget, &tsk->signal->shared_pending.signal, which); 2857 if (sigisemptyset(&retarget)) 2858 return; 2859 2860 t = tsk; 2861 while_each_thread(tsk, t) { 2862 if (t->flags & PF_EXITING) 2863 continue; 2864 2865 if (!has_pending_signals(&retarget, &t->blocked)) 2866 continue; 2867 /* Remove the signals this thread can handle. */ 2868 sigandsets(&retarget, &retarget, &t->blocked); 2869 2870 if (!task_sigpending(t)) 2871 signal_wake_up(t, 0); 2872 2873 if (sigisemptyset(&retarget)) 2874 break; 2875 } 2876 } 2877 2878 void exit_signals(struct task_struct *tsk) 2879 { 2880 int group_stop = 0; 2881 sigset_t unblocked; 2882 2883 /* 2884 * @tsk is about to have PF_EXITING set - lock out users which 2885 * expect stable threadgroup. 2886 */ 2887 cgroup_threadgroup_change_begin(tsk); 2888 2889 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) { 2890 tsk->flags |= PF_EXITING; 2891 cgroup_threadgroup_change_end(tsk); 2892 return; 2893 } 2894 2895 spin_lock_irq(&tsk->sighand->siglock); 2896 /* 2897 * From now this task is not visible for group-wide signals, 2898 * see wants_signal(), do_signal_stop(). 2899 */ 2900 tsk->flags |= PF_EXITING; 2901 2902 cgroup_threadgroup_change_end(tsk); 2903 2904 if (!task_sigpending(tsk)) 2905 goto out; 2906 2907 unblocked = tsk->blocked; 2908 signotset(&unblocked); 2909 retarget_shared_pending(tsk, &unblocked); 2910 2911 if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) && 2912 task_participate_group_stop(tsk)) 2913 group_stop = CLD_STOPPED; 2914 out: 2915 spin_unlock_irq(&tsk->sighand->siglock); 2916 2917 /* 2918 * If group stop has completed, deliver the notification. This 2919 * should always go to the real parent of the group leader. 2920 */ 2921 if (unlikely(group_stop)) { 2922 read_lock(&tasklist_lock); 2923 do_notify_parent_cldstop(tsk, false, group_stop); 2924 read_unlock(&tasklist_lock); 2925 } 2926 } 2927 2928 /* 2929 * System call entry points. 2930 */ 2931 2932 /** 2933 * sys_restart_syscall - restart a system call 2934 */ 2935 SYSCALL_DEFINE0(restart_syscall) 2936 { 2937 struct restart_block *restart = ¤t->restart_block; 2938 return restart->fn(restart); 2939 } 2940 2941 long do_no_restart_syscall(struct restart_block *param) 2942 { 2943 return -EINTR; 2944 } 2945 2946 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset) 2947 { 2948 if (task_sigpending(tsk) && !thread_group_empty(tsk)) { 2949 sigset_t newblocked; 2950 /* A set of now blocked but previously unblocked signals. */ 2951 sigandnsets(&newblocked, newset, ¤t->blocked); 2952 retarget_shared_pending(tsk, &newblocked); 2953 } 2954 tsk->blocked = *newset; 2955 recalc_sigpending(); 2956 } 2957 2958 /** 2959 * set_current_blocked - change current->blocked mask 2960 * @newset: new mask 2961 * 2962 * It is wrong to change ->blocked directly, this helper should be used 2963 * to ensure the process can't miss a shared signal we are going to block. 2964 */ 2965 void set_current_blocked(sigset_t *newset) 2966 { 2967 sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP)); 2968 __set_current_blocked(newset); 2969 } 2970 2971 void __set_current_blocked(const sigset_t *newset) 2972 { 2973 struct task_struct *tsk = current; 2974 2975 /* 2976 * In case the signal mask hasn't changed, there is nothing we need 2977 * to do. The current->blocked shouldn't be modified by other task. 2978 */ 2979 if (sigequalsets(&tsk->blocked, newset)) 2980 return; 2981 2982 spin_lock_irq(&tsk->sighand->siglock); 2983 __set_task_blocked(tsk, newset); 2984 spin_unlock_irq(&tsk->sighand->siglock); 2985 } 2986 2987 /* 2988 * This is also useful for kernel threads that want to temporarily 2989 * (or permanently) block certain signals. 2990 * 2991 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel 2992 * interface happily blocks "unblockable" signals like SIGKILL 2993 * and friends. 2994 */ 2995 int sigprocmask(int how, sigset_t *set, sigset_t *oldset) 2996 { 2997 struct task_struct *tsk = current; 2998 sigset_t newset; 2999 3000 /* Lockless, only current can change ->blocked, never from irq */ 3001 if (oldset) 3002 *oldset = tsk->blocked; 3003 3004 switch (how) { 3005 case SIG_BLOCK: 3006 sigorsets(&newset, &tsk->blocked, set); 3007 break; 3008 case SIG_UNBLOCK: 3009 sigandnsets(&newset, &tsk->blocked, set); 3010 break; 3011 case SIG_SETMASK: 3012 newset = *set; 3013 break; 3014 default: 3015 return -EINVAL; 3016 } 3017 3018 __set_current_blocked(&newset); 3019 return 0; 3020 } 3021 EXPORT_SYMBOL(sigprocmask); 3022 3023 /* 3024 * The api helps set app-provided sigmasks. 3025 * 3026 * This is useful for syscalls such as ppoll, pselect, io_pgetevents and 3027 * epoll_pwait where a new sigmask is passed from userland for the syscalls. 3028 * 3029 * Note that it does set_restore_sigmask() in advance, so it must be always 3030 * paired with restore_saved_sigmask_unless() before return from syscall. 3031 */ 3032 int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize) 3033 { 3034 sigset_t kmask; 3035 3036 if (!umask) 3037 return 0; 3038 if (sigsetsize != sizeof(sigset_t)) 3039 return -EINVAL; 3040 if (copy_from_user(&kmask, umask, sizeof(sigset_t))) 3041 return -EFAULT; 3042 3043 set_restore_sigmask(); 3044 current->saved_sigmask = current->blocked; 3045 set_current_blocked(&kmask); 3046 3047 return 0; 3048 } 3049 3050 #ifdef CONFIG_COMPAT 3051 int set_compat_user_sigmask(const compat_sigset_t __user *umask, 3052 size_t sigsetsize) 3053 { 3054 sigset_t kmask; 3055 3056 if (!umask) 3057 return 0; 3058 if (sigsetsize != sizeof(compat_sigset_t)) 3059 return -EINVAL; 3060 if (get_compat_sigset(&kmask, umask)) 3061 return -EFAULT; 3062 3063 set_restore_sigmask(); 3064 current->saved_sigmask = current->blocked; 3065 set_current_blocked(&kmask); 3066 3067 return 0; 3068 } 3069 #endif 3070 3071 /** 3072 * sys_rt_sigprocmask - change the list of currently blocked signals 3073 * @how: whether to add, remove, or set signals 3074 * @nset: stores pending signals 3075 * @oset: previous value of signal mask if non-null 3076 * @sigsetsize: size of sigset_t type 3077 */ 3078 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset, 3079 sigset_t __user *, oset, size_t, sigsetsize) 3080 { 3081 sigset_t old_set, new_set; 3082 int error; 3083 3084 /* XXX: Don't preclude handling different sized sigset_t's. */ 3085 if (sigsetsize != sizeof(sigset_t)) 3086 return -EINVAL; 3087 3088 old_set = current->blocked; 3089 3090 if (nset) { 3091 if (copy_from_user(&new_set, nset, sizeof(sigset_t))) 3092 return -EFAULT; 3093 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); 3094 3095 error = sigprocmask(how, &new_set, NULL); 3096 if (error) 3097 return error; 3098 } 3099 3100 if (oset) { 3101 if (copy_to_user(oset, &old_set, sizeof(sigset_t))) 3102 return -EFAULT; 3103 } 3104 3105 return 0; 3106 } 3107 3108 #ifdef CONFIG_COMPAT 3109 COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset, 3110 compat_sigset_t __user *, oset, compat_size_t, sigsetsize) 3111 { 3112 sigset_t old_set = current->blocked; 3113 3114 /* XXX: Don't preclude handling different sized sigset_t's. */ 3115 if (sigsetsize != sizeof(sigset_t)) 3116 return -EINVAL; 3117 3118 if (nset) { 3119 sigset_t new_set; 3120 int error; 3121 if (get_compat_sigset(&new_set, nset)) 3122 return -EFAULT; 3123 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); 3124 3125 error = sigprocmask(how, &new_set, NULL); 3126 if (error) 3127 return error; 3128 } 3129 return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0; 3130 } 3131 #endif 3132 3133 static void do_sigpending(sigset_t *set) 3134 { 3135 spin_lock_irq(¤t->sighand->siglock); 3136 sigorsets(set, ¤t->pending.signal, 3137 ¤t->signal->shared_pending.signal); 3138 spin_unlock_irq(¤t->sighand->siglock); 3139 3140 /* Outside the lock because only this thread touches it. */ 3141 sigandsets(set, ¤t->blocked, set); 3142 } 3143 3144 /** 3145 * sys_rt_sigpending - examine a pending signal that has been raised 3146 * while blocked 3147 * @uset: stores pending signals 3148 * @sigsetsize: size of sigset_t type or larger 3149 */ 3150 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize) 3151 { 3152 sigset_t set; 3153 3154 if (sigsetsize > sizeof(*uset)) 3155 return -EINVAL; 3156 3157 do_sigpending(&set); 3158 3159 if (copy_to_user(uset, &set, sigsetsize)) 3160 return -EFAULT; 3161 3162 return 0; 3163 } 3164 3165 #ifdef CONFIG_COMPAT 3166 COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset, 3167 compat_size_t, sigsetsize) 3168 { 3169 sigset_t set; 3170 3171 if (sigsetsize > sizeof(*uset)) 3172 return -EINVAL; 3173 3174 do_sigpending(&set); 3175 3176 return put_compat_sigset(uset, &set, sigsetsize); 3177 } 3178 #endif 3179 3180 static const struct { 3181 unsigned char limit, layout; 3182 } sig_sicodes[] = { 3183 [SIGILL] = { NSIGILL, SIL_FAULT }, 3184 [SIGFPE] = { NSIGFPE, SIL_FAULT }, 3185 [SIGSEGV] = { NSIGSEGV, SIL_FAULT }, 3186 [SIGBUS] = { NSIGBUS, SIL_FAULT }, 3187 [SIGTRAP] = { NSIGTRAP, SIL_FAULT }, 3188 #if defined(SIGEMT) 3189 [SIGEMT] = { NSIGEMT, SIL_FAULT }, 3190 #endif 3191 [SIGCHLD] = { NSIGCHLD, SIL_CHLD }, 3192 [SIGPOLL] = { NSIGPOLL, SIL_POLL }, 3193 [SIGSYS] = { NSIGSYS, SIL_SYS }, 3194 }; 3195 3196 static bool known_siginfo_layout(unsigned sig, int si_code) 3197 { 3198 if (si_code == SI_KERNEL) 3199 return true; 3200 else if ((si_code > SI_USER)) { 3201 if (sig_specific_sicodes(sig)) { 3202 if (si_code <= sig_sicodes[sig].limit) 3203 return true; 3204 } 3205 else if (si_code <= NSIGPOLL) 3206 return true; 3207 } 3208 else if (si_code >= SI_DETHREAD) 3209 return true; 3210 else if (si_code == SI_ASYNCNL) 3211 return true; 3212 return false; 3213 } 3214 3215 enum siginfo_layout siginfo_layout(unsigned sig, int si_code) 3216 { 3217 enum siginfo_layout layout = SIL_KILL; 3218 if ((si_code > SI_USER) && (si_code < SI_KERNEL)) { 3219 if ((sig < ARRAY_SIZE(sig_sicodes)) && 3220 (si_code <= sig_sicodes[sig].limit)) { 3221 layout = sig_sicodes[sig].layout; 3222 /* Handle the exceptions */ 3223 if ((sig == SIGBUS) && 3224 (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO)) 3225 layout = SIL_FAULT_MCEERR; 3226 else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR)) 3227 layout = SIL_FAULT_BNDERR; 3228 #ifdef SEGV_PKUERR 3229 else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR)) 3230 layout = SIL_FAULT_PKUERR; 3231 #endif 3232 else if ((sig == SIGTRAP) && (si_code == TRAP_PERF)) 3233 layout = SIL_PERF_EVENT; 3234 #ifdef __ARCH_SI_TRAPNO 3235 else if (layout == SIL_FAULT) 3236 layout = SIL_FAULT_TRAPNO; 3237 #endif 3238 } 3239 else if (si_code <= NSIGPOLL) 3240 layout = SIL_POLL; 3241 } else { 3242 if (si_code == SI_TIMER) 3243 layout = SIL_TIMER; 3244 else if (si_code == SI_SIGIO) 3245 layout = SIL_POLL; 3246 else if (si_code < 0) 3247 layout = SIL_RT; 3248 } 3249 return layout; 3250 } 3251 3252 static inline char __user *si_expansion(const siginfo_t __user *info) 3253 { 3254 return ((char __user *)info) + sizeof(struct kernel_siginfo); 3255 } 3256 3257 int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from) 3258 { 3259 char __user *expansion = si_expansion(to); 3260 if (copy_to_user(to, from , sizeof(struct kernel_siginfo))) 3261 return -EFAULT; 3262 if (clear_user(expansion, SI_EXPANSION_SIZE)) 3263 return -EFAULT; 3264 return 0; 3265 } 3266 3267 static int post_copy_siginfo_from_user(kernel_siginfo_t *info, 3268 const siginfo_t __user *from) 3269 { 3270 if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) { 3271 char __user *expansion = si_expansion(from); 3272 char buf[SI_EXPANSION_SIZE]; 3273 int i; 3274 /* 3275 * An unknown si_code might need more than 3276 * sizeof(struct kernel_siginfo) bytes. Verify all of the 3277 * extra bytes are 0. This guarantees copy_siginfo_to_user 3278 * will return this data to userspace exactly. 3279 */ 3280 if (copy_from_user(&buf, expansion, SI_EXPANSION_SIZE)) 3281 return -EFAULT; 3282 for (i = 0; i < SI_EXPANSION_SIZE; i++) { 3283 if (buf[i] != 0) 3284 return -E2BIG; 3285 } 3286 } 3287 return 0; 3288 } 3289 3290 static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to, 3291 const siginfo_t __user *from) 3292 { 3293 if (copy_from_user(to, from, sizeof(struct kernel_siginfo))) 3294 return -EFAULT; 3295 to->si_signo = signo; 3296 return post_copy_siginfo_from_user(to, from); 3297 } 3298 3299 int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from) 3300 { 3301 if (copy_from_user(to, from, sizeof(struct kernel_siginfo))) 3302 return -EFAULT; 3303 return post_copy_siginfo_from_user(to, from); 3304 } 3305 3306 #ifdef CONFIG_COMPAT 3307 /** 3308 * copy_siginfo_to_external32 - copy a kernel siginfo into a compat user siginfo 3309 * @to: compat siginfo destination 3310 * @from: kernel siginfo source 3311 * 3312 * Note: This function does not work properly for the SIGCHLD on x32, but 3313 * fortunately it doesn't have to. The only valid callers for this function are 3314 * copy_siginfo_to_user32, which is overriden for x32 and the coredump code. 3315 * The latter does not care because SIGCHLD will never cause a coredump. 3316 */ 3317 void copy_siginfo_to_external32(struct compat_siginfo *to, 3318 const struct kernel_siginfo *from) 3319 { 3320 memset(to, 0, sizeof(*to)); 3321 3322 to->si_signo = from->si_signo; 3323 to->si_errno = from->si_errno; 3324 to->si_code = from->si_code; 3325 switch(siginfo_layout(from->si_signo, from->si_code)) { 3326 case SIL_KILL: 3327 to->si_pid = from->si_pid; 3328 to->si_uid = from->si_uid; 3329 break; 3330 case SIL_TIMER: 3331 to->si_tid = from->si_tid; 3332 to->si_overrun = from->si_overrun; 3333 to->si_int = from->si_int; 3334 break; 3335 case SIL_POLL: 3336 to->si_band = from->si_band; 3337 to->si_fd = from->si_fd; 3338 break; 3339 case SIL_FAULT: 3340 to->si_addr = ptr_to_compat(from->si_addr); 3341 break; 3342 case SIL_FAULT_TRAPNO: 3343 to->si_addr = ptr_to_compat(from->si_addr); 3344 to->si_trapno = from->si_trapno; 3345 break; 3346 case SIL_FAULT_MCEERR: 3347 to->si_addr = ptr_to_compat(from->si_addr); 3348 to->si_addr_lsb = from->si_addr_lsb; 3349 break; 3350 case SIL_FAULT_BNDERR: 3351 to->si_addr = ptr_to_compat(from->si_addr); 3352 to->si_lower = ptr_to_compat(from->si_lower); 3353 to->si_upper = ptr_to_compat(from->si_upper); 3354 break; 3355 case SIL_FAULT_PKUERR: 3356 to->si_addr = ptr_to_compat(from->si_addr); 3357 to->si_pkey = from->si_pkey; 3358 break; 3359 case SIL_PERF_EVENT: 3360 to->si_addr = ptr_to_compat(from->si_addr); 3361 to->si_perf_data = from->si_perf_data; 3362 to->si_perf_type = from->si_perf_type; 3363 break; 3364 case SIL_CHLD: 3365 to->si_pid = from->si_pid; 3366 to->si_uid = from->si_uid; 3367 to->si_status = from->si_status; 3368 to->si_utime = from->si_utime; 3369 to->si_stime = from->si_stime; 3370 break; 3371 case SIL_RT: 3372 to->si_pid = from->si_pid; 3373 to->si_uid = from->si_uid; 3374 to->si_int = from->si_int; 3375 break; 3376 case SIL_SYS: 3377 to->si_call_addr = ptr_to_compat(from->si_call_addr); 3378 to->si_syscall = from->si_syscall; 3379 to->si_arch = from->si_arch; 3380 break; 3381 } 3382 } 3383 3384 int __copy_siginfo_to_user32(struct compat_siginfo __user *to, 3385 const struct kernel_siginfo *from) 3386 { 3387 struct compat_siginfo new; 3388 3389 copy_siginfo_to_external32(&new, from); 3390 if (copy_to_user(to, &new, sizeof(struct compat_siginfo))) 3391 return -EFAULT; 3392 return 0; 3393 } 3394 3395 static int post_copy_siginfo_from_user32(kernel_siginfo_t *to, 3396 const struct compat_siginfo *from) 3397 { 3398 clear_siginfo(to); 3399 to->si_signo = from->si_signo; 3400 to->si_errno = from->si_errno; 3401 to->si_code = from->si_code; 3402 switch(siginfo_layout(from->si_signo, from->si_code)) { 3403 case SIL_KILL: 3404 to->si_pid = from->si_pid; 3405 to->si_uid = from->si_uid; 3406 break; 3407 case SIL_TIMER: 3408 to->si_tid = from->si_tid; 3409 to->si_overrun = from->si_overrun; 3410 to->si_int = from->si_int; 3411 break; 3412 case SIL_POLL: 3413 to->si_band = from->si_band; 3414 to->si_fd = from->si_fd; 3415 break; 3416 case SIL_FAULT: 3417 to->si_addr = compat_ptr(from->si_addr); 3418 break; 3419 case SIL_FAULT_TRAPNO: 3420 to->si_addr = compat_ptr(from->si_addr); 3421 to->si_trapno = from->si_trapno; 3422 break; 3423 case SIL_FAULT_MCEERR: 3424 to->si_addr = compat_ptr(from->si_addr); 3425 to->si_addr_lsb = from->si_addr_lsb; 3426 break; 3427 case SIL_FAULT_BNDERR: 3428 to->si_addr = compat_ptr(from->si_addr); 3429 to->si_lower = compat_ptr(from->si_lower); 3430 to->si_upper = compat_ptr(from->si_upper); 3431 break; 3432 case SIL_FAULT_PKUERR: 3433 to->si_addr = compat_ptr(from->si_addr); 3434 to->si_pkey = from->si_pkey; 3435 break; 3436 case SIL_PERF_EVENT: 3437 to->si_addr = compat_ptr(from->si_addr); 3438 to->si_perf_data = from->si_perf_data; 3439 to->si_perf_type = from->si_perf_type; 3440 break; 3441 case SIL_CHLD: 3442 to->si_pid = from->si_pid; 3443 to->si_uid = from->si_uid; 3444 to->si_status = from->si_status; 3445 #ifdef CONFIG_X86_X32_ABI 3446 if (in_x32_syscall()) { 3447 to->si_utime = from->_sifields._sigchld_x32._utime; 3448 to->si_stime = from->_sifields._sigchld_x32._stime; 3449 } else 3450 #endif 3451 { 3452 to->si_utime = from->si_utime; 3453 to->si_stime = from->si_stime; 3454 } 3455 break; 3456 case SIL_RT: 3457 to->si_pid = from->si_pid; 3458 to->si_uid = from->si_uid; 3459 to->si_int = from->si_int; 3460 break; 3461 case SIL_SYS: 3462 to->si_call_addr = compat_ptr(from->si_call_addr); 3463 to->si_syscall = from->si_syscall; 3464 to->si_arch = from->si_arch; 3465 break; 3466 } 3467 return 0; 3468 } 3469 3470 static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to, 3471 const struct compat_siginfo __user *ufrom) 3472 { 3473 struct compat_siginfo from; 3474 3475 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo))) 3476 return -EFAULT; 3477 3478 from.si_signo = signo; 3479 return post_copy_siginfo_from_user32(to, &from); 3480 } 3481 3482 int copy_siginfo_from_user32(struct kernel_siginfo *to, 3483 const struct compat_siginfo __user *ufrom) 3484 { 3485 struct compat_siginfo from; 3486 3487 if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo))) 3488 return -EFAULT; 3489 3490 return post_copy_siginfo_from_user32(to, &from); 3491 } 3492 #endif /* CONFIG_COMPAT */ 3493 3494 /** 3495 * do_sigtimedwait - wait for queued signals specified in @which 3496 * @which: queued signals to wait for 3497 * @info: if non-null, the signal's siginfo is returned here 3498 * @ts: upper bound on process time suspension 3499 */ 3500 static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info, 3501 const struct timespec64 *ts) 3502 { 3503 ktime_t *to = NULL, timeout = KTIME_MAX; 3504 struct task_struct *tsk = current; 3505 sigset_t mask = *which; 3506 int sig, ret = 0; 3507 3508 if (ts) { 3509 if (!timespec64_valid(ts)) 3510 return -EINVAL; 3511 timeout = timespec64_to_ktime(*ts); 3512 to = &timeout; 3513 } 3514 3515 /* 3516 * Invert the set of allowed signals to get those we want to block. 3517 */ 3518 sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP)); 3519 signotset(&mask); 3520 3521 spin_lock_irq(&tsk->sighand->siglock); 3522 sig = dequeue_signal(tsk, &mask, info); 3523 if (!sig && timeout) { 3524 /* 3525 * None ready, temporarily unblock those we're interested 3526 * while we are sleeping in so that we'll be awakened when 3527 * they arrive. Unblocking is always fine, we can avoid 3528 * set_current_blocked(). 3529 */ 3530 tsk->real_blocked = tsk->blocked; 3531 sigandsets(&tsk->blocked, &tsk->blocked, &mask); 3532 recalc_sigpending(); 3533 spin_unlock_irq(&tsk->sighand->siglock); 3534 3535 __set_current_state(TASK_INTERRUPTIBLE); 3536 ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns, 3537 HRTIMER_MODE_REL); 3538 spin_lock_irq(&tsk->sighand->siglock); 3539 __set_task_blocked(tsk, &tsk->real_blocked); 3540 sigemptyset(&tsk->real_blocked); 3541 sig = dequeue_signal(tsk, &mask, info); 3542 } 3543 spin_unlock_irq(&tsk->sighand->siglock); 3544 3545 if (sig) 3546 return sig; 3547 return ret ? -EINTR : -EAGAIN; 3548 } 3549 3550 /** 3551 * sys_rt_sigtimedwait - synchronously wait for queued signals specified 3552 * in @uthese 3553 * @uthese: queued signals to wait for 3554 * @uinfo: if non-null, the signal's siginfo is returned here 3555 * @uts: upper bound on process time suspension 3556 * @sigsetsize: size of sigset_t type 3557 */ 3558 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese, 3559 siginfo_t __user *, uinfo, 3560 const struct __kernel_timespec __user *, uts, 3561 size_t, sigsetsize) 3562 { 3563 sigset_t these; 3564 struct timespec64 ts; 3565 kernel_siginfo_t info; 3566 int ret; 3567 3568 /* XXX: Don't preclude handling different sized sigset_t's. */ 3569 if (sigsetsize != sizeof(sigset_t)) 3570 return -EINVAL; 3571 3572 if (copy_from_user(&these, uthese, sizeof(these))) 3573 return -EFAULT; 3574 3575 if (uts) { 3576 if (get_timespec64(&ts, uts)) 3577 return -EFAULT; 3578 } 3579 3580 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL); 3581 3582 if (ret > 0 && uinfo) { 3583 if (copy_siginfo_to_user(uinfo, &info)) 3584 ret = -EFAULT; 3585 } 3586 3587 return ret; 3588 } 3589 3590 #ifdef CONFIG_COMPAT_32BIT_TIME 3591 SYSCALL_DEFINE4(rt_sigtimedwait_time32, const sigset_t __user *, uthese, 3592 siginfo_t __user *, uinfo, 3593 const struct old_timespec32 __user *, uts, 3594 size_t, sigsetsize) 3595 { 3596 sigset_t these; 3597 struct timespec64 ts; 3598 kernel_siginfo_t info; 3599 int ret; 3600 3601 if (sigsetsize != sizeof(sigset_t)) 3602 return -EINVAL; 3603 3604 if (copy_from_user(&these, uthese, sizeof(these))) 3605 return -EFAULT; 3606 3607 if (uts) { 3608 if (get_old_timespec32(&ts, uts)) 3609 return -EFAULT; 3610 } 3611 3612 ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL); 3613 3614 if (ret > 0 && uinfo) { 3615 if (copy_siginfo_to_user(uinfo, &info)) 3616 ret = -EFAULT; 3617 } 3618 3619 return ret; 3620 } 3621 #endif 3622 3623 #ifdef CONFIG_COMPAT 3624 COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time64, compat_sigset_t __user *, uthese, 3625 struct compat_siginfo __user *, uinfo, 3626 struct __kernel_timespec __user *, uts, compat_size_t, sigsetsize) 3627 { 3628 sigset_t s; 3629 struct timespec64 t; 3630 kernel_siginfo_t info; 3631 long ret; 3632 3633 if (sigsetsize != sizeof(sigset_t)) 3634 return -EINVAL; 3635 3636 if (get_compat_sigset(&s, uthese)) 3637 return -EFAULT; 3638 3639 if (uts) { 3640 if (get_timespec64(&t, uts)) 3641 return -EFAULT; 3642 } 3643 3644 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL); 3645 3646 if (ret > 0 && uinfo) { 3647 if (copy_siginfo_to_user32(uinfo, &info)) 3648 ret = -EFAULT; 3649 } 3650 3651 return ret; 3652 } 3653 3654 #ifdef CONFIG_COMPAT_32BIT_TIME 3655 COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait_time32, compat_sigset_t __user *, uthese, 3656 struct compat_siginfo __user *, uinfo, 3657 struct old_timespec32 __user *, uts, compat_size_t, sigsetsize) 3658 { 3659 sigset_t s; 3660 struct timespec64 t; 3661 kernel_siginfo_t info; 3662 long ret; 3663 3664 if (sigsetsize != sizeof(sigset_t)) 3665 return -EINVAL; 3666 3667 if (get_compat_sigset(&s, uthese)) 3668 return -EFAULT; 3669 3670 if (uts) { 3671 if (get_old_timespec32(&t, uts)) 3672 return -EFAULT; 3673 } 3674 3675 ret = do_sigtimedwait(&s, &info, uts ? &t : NULL); 3676 3677 if (ret > 0 && uinfo) { 3678 if (copy_siginfo_to_user32(uinfo, &info)) 3679 ret = -EFAULT; 3680 } 3681 3682 return ret; 3683 } 3684 #endif 3685 #endif 3686 3687 static inline void prepare_kill_siginfo(int sig, struct kernel_siginfo *info) 3688 { 3689 clear_siginfo(info); 3690 info->si_signo = sig; 3691 info->si_errno = 0; 3692 info->si_code = SI_USER; 3693 info->si_pid = task_tgid_vnr(current); 3694 info->si_uid = from_kuid_munged(current_user_ns(), current_uid()); 3695 } 3696 3697 /** 3698 * sys_kill - send a signal to a process 3699 * @pid: the PID of the process 3700 * @sig: signal to be sent 3701 */ 3702 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig) 3703 { 3704 struct kernel_siginfo info; 3705 3706 prepare_kill_siginfo(sig, &info); 3707 3708 return kill_something_info(sig, &info, pid); 3709 } 3710 3711 /* 3712 * Verify that the signaler and signalee either are in the same pid namespace 3713 * or that the signaler's pid namespace is an ancestor of the signalee's pid 3714 * namespace. 3715 */ 3716 static bool access_pidfd_pidns(struct pid *pid) 3717 { 3718 struct pid_namespace *active = task_active_pid_ns(current); 3719 struct pid_namespace *p = ns_of_pid(pid); 3720 3721 for (;;) { 3722 if (!p) 3723 return false; 3724 if (p == active) 3725 break; 3726 p = p->parent; 3727 } 3728 3729 return true; 3730 } 3731 3732 static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo, 3733 siginfo_t __user *info) 3734 { 3735 #ifdef CONFIG_COMPAT 3736 /* 3737 * Avoid hooking up compat syscalls and instead handle necessary 3738 * conversions here. Note, this is a stop-gap measure and should not be 3739 * considered a generic solution. 3740 */ 3741 if (in_compat_syscall()) 3742 return copy_siginfo_from_user32( 3743 kinfo, (struct compat_siginfo __user *)info); 3744 #endif 3745 return copy_siginfo_from_user(kinfo, info); 3746 } 3747 3748 static struct pid *pidfd_to_pid(const struct file *file) 3749 { 3750 struct pid *pid; 3751 3752 pid = pidfd_pid(file); 3753 if (!IS_ERR(pid)) 3754 return pid; 3755 3756 return tgid_pidfd_to_pid(file); 3757 } 3758 3759 /** 3760 * sys_pidfd_send_signal - Signal a process through a pidfd 3761 * @pidfd: file descriptor of the process 3762 * @sig: signal to send 3763 * @info: signal info 3764 * @flags: future flags 3765 * 3766 * The syscall currently only signals via PIDTYPE_PID which covers 3767 * kill(<positive-pid>, <signal>. It does not signal threads or process 3768 * groups. 3769 * In order to extend the syscall to threads and process groups the @flags 3770 * argument should be used. In essence, the @flags argument will determine 3771 * what is signaled and not the file descriptor itself. Put in other words, 3772 * grouping is a property of the flags argument not a property of the file 3773 * descriptor. 3774 * 3775 * Return: 0 on success, negative errno on failure 3776 */ 3777 SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig, 3778 siginfo_t __user *, info, unsigned int, flags) 3779 { 3780 int ret; 3781 struct fd f; 3782 struct pid *pid; 3783 kernel_siginfo_t kinfo; 3784 3785 /* Enforce flags be set to 0 until we add an extension. */ 3786 if (flags) 3787 return -EINVAL; 3788 3789 f = fdget(pidfd); 3790 if (!f.file) 3791 return -EBADF; 3792 3793 /* Is this a pidfd? */ 3794 pid = pidfd_to_pid(f.file); 3795 if (IS_ERR(pid)) { 3796 ret = PTR_ERR(pid); 3797 goto err; 3798 } 3799 3800 ret = -EINVAL; 3801 if (!access_pidfd_pidns(pid)) 3802 goto err; 3803 3804 if (info) { 3805 ret = copy_siginfo_from_user_any(&kinfo, info); 3806 if (unlikely(ret)) 3807 goto err; 3808 3809 ret = -EINVAL; 3810 if (unlikely(sig != kinfo.si_signo)) 3811 goto err; 3812 3813 /* Only allow sending arbitrary signals to yourself. */ 3814 ret = -EPERM; 3815 if ((task_pid(current) != pid) && 3816 (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL)) 3817 goto err; 3818 } else { 3819 prepare_kill_siginfo(sig, &kinfo); 3820 } 3821 3822 ret = kill_pid_info(sig, &kinfo, pid); 3823 3824 err: 3825 fdput(f); 3826 return ret; 3827 } 3828 3829 static int 3830 do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info) 3831 { 3832 struct task_struct *p; 3833 int error = -ESRCH; 3834 3835 rcu_read_lock(); 3836 p = find_task_by_vpid(pid); 3837 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) { 3838 error = check_kill_permission(sig, info, p); 3839 /* 3840 * The null signal is a permissions and process existence 3841 * probe. No signal is actually delivered. 3842 */ 3843 if (!error && sig) { 3844 error = do_send_sig_info(sig, info, p, PIDTYPE_PID); 3845 /* 3846 * If lock_task_sighand() failed we pretend the task 3847 * dies after receiving the signal. The window is tiny, 3848 * and the signal is private anyway. 3849 */ 3850 if (unlikely(error == -ESRCH)) 3851 error = 0; 3852 } 3853 } 3854 rcu_read_unlock(); 3855 3856 return error; 3857 } 3858 3859 static int do_tkill(pid_t tgid, pid_t pid, int sig) 3860 { 3861 struct kernel_siginfo info; 3862 3863 clear_siginfo(&info); 3864 info.si_signo = sig; 3865 info.si_errno = 0; 3866 info.si_code = SI_TKILL; 3867 info.si_pid = task_tgid_vnr(current); 3868 info.si_uid = from_kuid_munged(current_user_ns(), current_uid()); 3869 3870 return do_send_specific(tgid, pid, sig, &info); 3871 } 3872 3873 /** 3874 * sys_tgkill - send signal to one specific thread 3875 * @tgid: the thread group ID of the thread 3876 * @pid: the PID of the thread 3877 * @sig: signal to be sent 3878 * 3879 * This syscall also checks the @tgid and returns -ESRCH even if the PID 3880 * exists but it's not belonging to the target process anymore. This 3881 * method solves the problem of threads exiting and PIDs getting reused. 3882 */ 3883 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig) 3884 { 3885 /* This is only valid for single tasks */ 3886 if (pid <= 0 || tgid <= 0) 3887 return -EINVAL; 3888 3889 return do_tkill(tgid, pid, sig); 3890 } 3891 3892 /** 3893 * sys_tkill - send signal to one specific task 3894 * @pid: the PID of the task 3895 * @sig: signal to be sent 3896 * 3897 * Send a signal to only one task, even if it's a CLONE_THREAD task. 3898 */ 3899 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig) 3900 { 3901 /* This is only valid for single tasks */ 3902 if (pid <= 0) 3903 return -EINVAL; 3904 3905 return do_tkill(0, pid, sig); 3906 } 3907 3908 static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info) 3909 { 3910 /* Not even root can pretend to send signals from the kernel. 3911 * Nor can they impersonate a kill()/tgkill(), which adds source info. 3912 */ 3913 if ((info->si_code >= 0 || info->si_code == SI_TKILL) && 3914 (task_pid_vnr(current) != pid)) 3915 return -EPERM; 3916 3917 /* POSIX.1b doesn't mention process groups. */ 3918 return kill_proc_info(sig, info, pid); 3919 } 3920 3921 /** 3922 * sys_rt_sigqueueinfo - send signal information to a signal 3923 * @pid: the PID of the thread 3924 * @sig: signal to be sent 3925 * @uinfo: signal info to be sent 3926 */ 3927 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig, 3928 siginfo_t __user *, uinfo) 3929 { 3930 kernel_siginfo_t info; 3931 int ret = __copy_siginfo_from_user(sig, &info, uinfo); 3932 if (unlikely(ret)) 3933 return ret; 3934 return do_rt_sigqueueinfo(pid, sig, &info); 3935 } 3936 3937 #ifdef CONFIG_COMPAT 3938 COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo, 3939 compat_pid_t, pid, 3940 int, sig, 3941 struct compat_siginfo __user *, uinfo) 3942 { 3943 kernel_siginfo_t info; 3944 int ret = __copy_siginfo_from_user32(sig, &info, uinfo); 3945 if (unlikely(ret)) 3946 return ret; 3947 return do_rt_sigqueueinfo(pid, sig, &info); 3948 } 3949 #endif 3950 3951 static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t *info) 3952 { 3953 /* This is only valid for single tasks */ 3954 if (pid <= 0 || tgid <= 0) 3955 return -EINVAL; 3956 3957 /* Not even root can pretend to send signals from the kernel. 3958 * Nor can they impersonate a kill()/tgkill(), which adds source info. 3959 */ 3960 if ((info->si_code >= 0 || info->si_code == SI_TKILL) && 3961 (task_pid_vnr(current) != pid)) 3962 return -EPERM; 3963 3964 return do_send_specific(tgid, pid, sig, info); 3965 } 3966 3967 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig, 3968 siginfo_t __user *, uinfo) 3969 { 3970 kernel_siginfo_t info; 3971 int ret = __copy_siginfo_from_user(sig, &info, uinfo); 3972 if (unlikely(ret)) 3973 return ret; 3974 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info); 3975 } 3976 3977 #ifdef CONFIG_COMPAT 3978 COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo, 3979 compat_pid_t, tgid, 3980 compat_pid_t, pid, 3981 int, sig, 3982 struct compat_siginfo __user *, uinfo) 3983 { 3984 kernel_siginfo_t info; 3985 int ret = __copy_siginfo_from_user32(sig, &info, uinfo); 3986 if (unlikely(ret)) 3987 return ret; 3988 return do_rt_tgsigqueueinfo(tgid, pid, sig, &info); 3989 } 3990 #endif 3991 3992 /* 3993 * For kthreads only, must not be used if cloned with CLONE_SIGHAND 3994 */ 3995 void kernel_sigaction(int sig, __sighandler_t action) 3996 { 3997 spin_lock_irq(¤t->sighand->siglock); 3998 current->sighand->action[sig - 1].sa.sa_handler = action; 3999 if (action == SIG_IGN) { 4000 sigset_t mask; 4001 4002 sigemptyset(&mask); 4003 sigaddset(&mask, sig); 4004 4005 flush_sigqueue_mask(&mask, ¤t->signal->shared_pending); 4006 flush_sigqueue_mask(&mask, ¤t->pending); 4007 recalc_sigpending(); 4008 } 4009 spin_unlock_irq(¤t->sighand->siglock); 4010 } 4011 EXPORT_SYMBOL(kernel_sigaction); 4012 4013 void __weak sigaction_compat_abi(struct k_sigaction *act, 4014 struct k_sigaction *oact) 4015 { 4016 } 4017 4018 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) 4019 { 4020 struct task_struct *p = current, *t; 4021 struct k_sigaction *k; 4022 sigset_t mask; 4023 4024 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig))) 4025 return -EINVAL; 4026 4027 k = &p->sighand->action[sig-1]; 4028 4029 spin_lock_irq(&p->sighand->siglock); 4030 if (oact) 4031 *oact = *k; 4032 4033 /* 4034 * Make sure that we never accidentally claim to support SA_UNSUPPORTED, 4035 * e.g. by having an architecture use the bit in their uapi. 4036 */ 4037 BUILD_BUG_ON(UAPI_SA_FLAGS & SA_UNSUPPORTED); 4038 4039 /* 4040 * Clear unknown flag bits in order to allow userspace to detect missing 4041 * support for flag bits and to allow the kernel to use non-uapi bits 4042 * internally. 4043 */ 4044 if (act) 4045 act->sa.sa_flags &= UAPI_SA_FLAGS; 4046 if (oact) 4047 oact->sa.sa_flags &= UAPI_SA_FLAGS; 4048 4049 sigaction_compat_abi(act, oact); 4050 4051 if (act) { 4052 sigdelsetmask(&act->sa.sa_mask, 4053 sigmask(SIGKILL) | sigmask(SIGSTOP)); 4054 *k = *act; 4055 /* 4056 * POSIX 3.3.1.3: 4057 * "Setting a signal action to SIG_IGN for a signal that is 4058 * pending shall cause the pending signal to be discarded, 4059 * whether or not it is blocked." 4060 * 4061 * "Setting a signal action to SIG_DFL for a signal that is 4062 * pending and whose default action is to ignore the signal 4063 * (for example, SIGCHLD), shall cause the pending signal to 4064 * be discarded, whether or not it is blocked" 4065 */ 4066 if (sig_handler_ignored(sig_handler(p, sig), sig)) { 4067 sigemptyset(&mask); 4068 sigaddset(&mask, sig); 4069 flush_sigqueue_mask(&mask, &p->signal->shared_pending); 4070 for_each_thread(p, t) 4071 flush_sigqueue_mask(&mask, &t->pending); 4072 } 4073 } 4074 4075 spin_unlock_irq(&p->sighand->siglock); 4076 return 0; 4077 } 4078 4079 static int 4080 do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp, 4081 size_t min_ss_size) 4082 { 4083 struct task_struct *t = current; 4084 4085 if (oss) { 4086 memset(oss, 0, sizeof(stack_t)); 4087 oss->ss_sp = (void __user *) t->sas_ss_sp; 4088 oss->ss_size = t->sas_ss_size; 4089 oss->ss_flags = sas_ss_flags(sp) | 4090 (current->sas_ss_flags & SS_FLAG_BITS); 4091 } 4092 4093 if (ss) { 4094 void __user *ss_sp = ss->ss_sp; 4095 size_t ss_size = ss->ss_size; 4096 unsigned ss_flags = ss->ss_flags; 4097 int ss_mode; 4098 4099 if (unlikely(on_sig_stack(sp))) 4100 return -EPERM; 4101 4102 ss_mode = ss_flags & ~SS_FLAG_BITS; 4103 if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK && 4104 ss_mode != 0)) 4105 return -EINVAL; 4106 4107 if (ss_mode == SS_DISABLE) { 4108 ss_size = 0; 4109 ss_sp = NULL; 4110 } else { 4111 if (unlikely(ss_size < min_ss_size)) 4112 return -ENOMEM; 4113 } 4114 4115 t->sas_ss_sp = (unsigned long) ss_sp; 4116 t->sas_ss_size = ss_size; 4117 t->sas_ss_flags = ss_flags; 4118 } 4119 return 0; 4120 } 4121 4122 SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss) 4123 { 4124 stack_t new, old; 4125 int err; 4126 if (uss && copy_from_user(&new, uss, sizeof(stack_t))) 4127 return -EFAULT; 4128 err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL, 4129 current_user_stack_pointer(), 4130 MINSIGSTKSZ); 4131 if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t))) 4132 err = -EFAULT; 4133 return err; 4134 } 4135 4136 int restore_altstack(const stack_t __user *uss) 4137 { 4138 stack_t new; 4139 if (copy_from_user(&new, uss, sizeof(stack_t))) 4140 return -EFAULT; 4141 (void)do_sigaltstack(&new, NULL, current_user_stack_pointer(), 4142 MINSIGSTKSZ); 4143 /* squash all but EFAULT for now */ 4144 return 0; 4145 } 4146 4147 int __save_altstack(stack_t __user *uss, unsigned long sp) 4148 { 4149 struct task_struct *t = current; 4150 int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) | 4151 __put_user(t->sas_ss_flags, &uss->ss_flags) | 4152 __put_user(t->sas_ss_size, &uss->ss_size); 4153 return err; 4154 } 4155 4156 #ifdef CONFIG_COMPAT 4157 static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr, 4158 compat_stack_t __user *uoss_ptr) 4159 { 4160 stack_t uss, uoss; 4161 int ret; 4162 4163 if (uss_ptr) { 4164 compat_stack_t uss32; 4165 if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t))) 4166 return -EFAULT; 4167 uss.ss_sp = compat_ptr(uss32.ss_sp); 4168 uss.ss_flags = uss32.ss_flags; 4169 uss.ss_size = uss32.ss_size; 4170 } 4171 ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss, 4172 compat_user_stack_pointer(), 4173 COMPAT_MINSIGSTKSZ); 4174 if (ret >= 0 && uoss_ptr) { 4175 compat_stack_t old; 4176 memset(&old, 0, sizeof(old)); 4177 old.ss_sp = ptr_to_compat(uoss.ss_sp); 4178 old.ss_flags = uoss.ss_flags; 4179 old.ss_size = uoss.ss_size; 4180 if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t))) 4181 ret = -EFAULT; 4182 } 4183 return ret; 4184 } 4185 4186 COMPAT_SYSCALL_DEFINE2(sigaltstack, 4187 const compat_stack_t __user *, uss_ptr, 4188 compat_stack_t __user *, uoss_ptr) 4189 { 4190 return do_compat_sigaltstack(uss_ptr, uoss_ptr); 4191 } 4192 4193 int compat_restore_altstack(const compat_stack_t __user *uss) 4194 { 4195 int err = do_compat_sigaltstack(uss, NULL); 4196 /* squash all but -EFAULT for now */ 4197 return err == -EFAULT ? err : 0; 4198 } 4199 4200 int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp) 4201 { 4202 int err; 4203 struct task_struct *t = current; 4204 err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), 4205 &uss->ss_sp) | 4206 __put_user(t->sas_ss_flags, &uss->ss_flags) | 4207 __put_user(t->sas_ss_size, &uss->ss_size); 4208 return err; 4209 } 4210 #endif 4211 4212 #ifdef __ARCH_WANT_SYS_SIGPENDING 4213 4214 /** 4215 * sys_sigpending - examine pending signals 4216 * @uset: where mask of pending signal is returned 4217 */ 4218 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset) 4219 { 4220 sigset_t set; 4221 4222 if (sizeof(old_sigset_t) > sizeof(*uset)) 4223 return -EINVAL; 4224 4225 do_sigpending(&set); 4226 4227 if (copy_to_user(uset, &set, sizeof(old_sigset_t))) 4228 return -EFAULT; 4229 4230 return 0; 4231 } 4232 4233 #ifdef CONFIG_COMPAT 4234 COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32) 4235 { 4236 sigset_t set; 4237 4238 do_sigpending(&set); 4239 4240 return put_user(set.sig[0], set32); 4241 } 4242 #endif 4243 4244 #endif 4245 4246 #ifdef __ARCH_WANT_SYS_SIGPROCMASK 4247 /** 4248 * sys_sigprocmask - examine and change blocked signals 4249 * @how: whether to add, remove, or set signals 4250 * @nset: signals to add or remove (if non-null) 4251 * @oset: previous value of signal mask if non-null 4252 * 4253 * Some platforms have their own version with special arguments; 4254 * others support only sys_rt_sigprocmask. 4255 */ 4256 4257 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset, 4258 old_sigset_t __user *, oset) 4259 { 4260 old_sigset_t old_set, new_set; 4261 sigset_t new_blocked; 4262 4263 old_set = current->blocked.sig[0]; 4264 4265 if (nset) { 4266 if (copy_from_user(&new_set, nset, sizeof(*nset))) 4267 return -EFAULT; 4268 4269 new_blocked = current->blocked; 4270 4271 switch (how) { 4272 case SIG_BLOCK: 4273 sigaddsetmask(&new_blocked, new_set); 4274 break; 4275 case SIG_UNBLOCK: 4276 sigdelsetmask(&new_blocked, new_set); 4277 break; 4278 case SIG_SETMASK: 4279 new_blocked.sig[0] = new_set; 4280 break; 4281 default: 4282 return -EINVAL; 4283 } 4284 4285 set_current_blocked(&new_blocked); 4286 } 4287 4288 if (oset) { 4289 if (copy_to_user(oset, &old_set, sizeof(*oset))) 4290 return -EFAULT; 4291 } 4292 4293 return 0; 4294 } 4295 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */ 4296 4297 #ifndef CONFIG_ODD_RT_SIGACTION 4298 /** 4299 * sys_rt_sigaction - alter an action taken by a process 4300 * @sig: signal to be sent 4301 * @act: new sigaction 4302 * @oact: used to save the previous sigaction 4303 * @sigsetsize: size of sigset_t type 4304 */ 4305 SYSCALL_DEFINE4(rt_sigaction, int, sig, 4306 const struct sigaction __user *, act, 4307 struct sigaction __user *, oact, 4308 size_t, sigsetsize) 4309 { 4310 struct k_sigaction new_sa, old_sa; 4311 int ret; 4312 4313 /* XXX: Don't preclude handling different sized sigset_t's. */ 4314 if (sigsetsize != sizeof(sigset_t)) 4315 return -EINVAL; 4316 4317 if (act && copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa))) 4318 return -EFAULT; 4319 4320 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL); 4321 if (ret) 4322 return ret; 4323 4324 if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa))) 4325 return -EFAULT; 4326 4327 return 0; 4328 } 4329 #ifdef CONFIG_COMPAT 4330 COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig, 4331 const struct compat_sigaction __user *, act, 4332 struct compat_sigaction __user *, oact, 4333 compat_size_t, sigsetsize) 4334 { 4335 struct k_sigaction new_ka, old_ka; 4336 #ifdef __ARCH_HAS_SA_RESTORER 4337 compat_uptr_t restorer; 4338 #endif 4339 int ret; 4340 4341 /* XXX: Don't preclude handling different sized sigset_t's. */ 4342 if (sigsetsize != sizeof(compat_sigset_t)) 4343 return -EINVAL; 4344 4345 if (act) { 4346 compat_uptr_t handler; 4347 ret = get_user(handler, &act->sa_handler); 4348 new_ka.sa.sa_handler = compat_ptr(handler); 4349 #ifdef __ARCH_HAS_SA_RESTORER 4350 ret |= get_user(restorer, &act->sa_restorer); 4351 new_ka.sa.sa_restorer = compat_ptr(restorer); 4352 #endif 4353 ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask); 4354 ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags); 4355 if (ret) 4356 return -EFAULT; 4357 } 4358 4359 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); 4360 if (!ret && oact) { 4361 ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), 4362 &oact->sa_handler); 4363 ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask, 4364 sizeof(oact->sa_mask)); 4365 ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags); 4366 #ifdef __ARCH_HAS_SA_RESTORER 4367 ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer), 4368 &oact->sa_restorer); 4369 #endif 4370 } 4371 return ret; 4372 } 4373 #endif 4374 #endif /* !CONFIG_ODD_RT_SIGACTION */ 4375 4376 #ifdef CONFIG_OLD_SIGACTION 4377 SYSCALL_DEFINE3(sigaction, int, sig, 4378 const struct old_sigaction __user *, act, 4379 struct old_sigaction __user *, oact) 4380 { 4381 struct k_sigaction new_ka, old_ka; 4382 int ret; 4383 4384 if (act) { 4385 old_sigset_t mask; 4386 if (!access_ok(act, sizeof(*act)) || 4387 __get_user(new_ka.sa.sa_handler, &act->sa_handler) || 4388 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) || 4389 __get_user(new_ka.sa.sa_flags, &act->sa_flags) || 4390 __get_user(mask, &act->sa_mask)) 4391 return -EFAULT; 4392 #ifdef __ARCH_HAS_KA_RESTORER 4393 new_ka.ka_restorer = NULL; 4394 #endif 4395 siginitset(&new_ka.sa.sa_mask, mask); 4396 } 4397 4398 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); 4399 4400 if (!ret && oact) { 4401 if (!access_ok(oact, sizeof(*oact)) || 4402 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) || 4403 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) || 4404 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) || 4405 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask)) 4406 return -EFAULT; 4407 } 4408 4409 return ret; 4410 } 4411 #endif 4412 #ifdef CONFIG_COMPAT_OLD_SIGACTION 4413 COMPAT_SYSCALL_DEFINE3(sigaction, int, sig, 4414 const struct compat_old_sigaction __user *, act, 4415 struct compat_old_sigaction __user *, oact) 4416 { 4417 struct k_sigaction new_ka, old_ka; 4418 int ret; 4419 compat_old_sigset_t mask; 4420 compat_uptr_t handler, restorer; 4421 4422 if (act) { 4423 if (!access_ok(act, sizeof(*act)) || 4424 __get_user(handler, &act->sa_handler) || 4425 __get_user(restorer, &act->sa_restorer) || 4426 __get_user(new_ka.sa.sa_flags, &act->sa_flags) || 4427 __get_user(mask, &act->sa_mask)) 4428 return -EFAULT; 4429 4430 #ifdef __ARCH_HAS_KA_RESTORER 4431 new_ka.ka_restorer = NULL; 4432 #endif 4433 new_ka.sa.sa_handler = compat_ptr(handler); 4434 new_ka.sa.sa_restorer = compat_ptr(restorer); 4435 siginitset(&new_ka.sa.sa_mask, mask); 4436 } 4437 4438 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); 4439 4440 if (!ret && oact) { 4441 if (!access_ok(oact, sizeof(*oact)) || 4442 __put_user(ptr_to_compat(old_ka.sa.sa_handler), 4443 &oact->sa_handler) || 4444 __put_user(ptr_to_compat(old_ka.sa.sa_restorer), 4445 &oact->sa_restorer) || 4446 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) || 4447 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask)) 4448 return -EFAULT; 4449 } 4450 return ret; 4451 } 4452 #endif 4453 4454 #ifdef CONFIG_SGETMASK_SYSCALL 4455 4456 /* 4457 * For backwards compatibility. Functionality superseded by sigprocmask. 4458 */ 4459 SYSCALL_DEFINE0(sgetmask) 4460 { 4461 /* SMP safe */ 4462 return current->blocked.sig[0]; 4463 } 4464 4465 SYSCALL_DEFINE1(ssetmask, int, newmask) 4466 { 4467 int old = current->blocked.sig[0]; 4468 sigset_t newset; 4469 4470 siginitset(&newset, newmask); 4471 set_current_blocked(&newset); 4472 4473 return old; 4474 } 4475 #endif /* CONFIG_SGETMASK_SYSCALL */ 4476 4477 #ifdef __ARCH_WANT_SYS_SIGNAL 4478 /* 4479 * For backwards compatibility. Functionality superseded by sigaction. 4480 */ 4481 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler) 4482 { 4483 struct k_sigaction new_sa, old_sa; 4484 int ret; 4485 4486 new_sa.sa.sa_handler = handler; 4487 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK; 4488 sigemptyset(&new_sa.sa.sa_mask); 4489 4490 ret = do_sigaction(sig, &new_sa, &old_sa); 4491 4492 return ret ? ret : (unsigned long)old_sa.sa.sa_handler; 4493 } 4494 #endif /* __ARCH_WANT_SYS_SIGNAL */ 4495 4496 #ifdef __ARCH_WANT_SYS_PAUSE 4497 4498 SYSCALL_DEFINE0(pause) 4499 { 4500 while (!signal_pending(current)) { 4501 __set_current_state(TASK_INTERRUPTIBLE); 4502 schedule(); 4503 } 4504 return -ERESTARTNOHAND; 4505 } 4506 4507 #endif 4508 4509 static int sigsuspend(sigset_t *set) 4510 { 4511 current->saved_sigmask = current->blocked; 4512 set_current_blocked(set); 4513 4514 while (!signal_pending(current)) { 4515 __set_current_state(TASK_INTERRUPTIBLE); 4516 schedule(); 4517 } 4518 set_restore_sigmask(); 4519 return -ERESTARTNOHAND; 4520 } 4521 4522 /** 4523 * sys_rt_sigsuspend - replace the signal mask for a value with the 4524 * @unewset value until a signal is received 4525 * @unewset: new signal mask value 4526 * @sigsetsize: size of sigset_t type 4527 */ 4528 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize) 4529 { 4530 sigset_t newset; 4531 4532 /* XXX: Don't preclude handling different sized sigset_t's. */ 4533 if (sigsetsize != sizeof(sigset_t)) 4534 return -EINVAL; 4535 4536 if (copy_from_user(&newset, unewset, sizeof(newset))) 4537 return -EFAULT; 4538 return sigsuspend(&newset); 4539 } 4540 4541 #ifdef CONFIG_COMPAT 4542 COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize) 4543 { 4544 sigset_t newset; 4545 4546 /* XXX: Don't preclude handling different sized sigset_t's. */ 4547 if (sigsetsize != sizeof(sigset_t)) 4548 return -EINVAL; 4549 4550 if (get_compat_sigset(&newset, unewset)) 4551 return -EFAULT; 4552 return sigsuspend(&newset); 4553 } 4554 #endif 4555 4556 #ifdef CONFIG_OLD_SIGSUSPEND 4557 SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask) 4558 { 4559 sigset_t blocked; 4560 siginitset(&blocked, mask); 4561 return sigsuspend(&blocked); 4562 } 4563 #endif 4564 #ifdef CONFIG_OLD_SIGSUSPEND3 4565 SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask) 4566 { 4567 sigset_t blocked; 4568 siginitset(&blocked, mask); 4569 return sigsuspend(&blocked); 4570 } 4571 #endif 4572 4573 __weak const char *arch_vma_name(struct vm_area_struct *vma) 4574 { 4575 return NULL; 4576 } 4577 4578 static inline void siginfo_buildtime_checks(void) 4579 { 4580 BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE); 4581 4582 /* Verify the offsets in the two siginfos match */ 4583 #define CHECK_OFFSET(field) \ 4584 BUILD_BUG_ON(offsetof(siginfo_t, field) != offsetof(kernel_siginfo_t, field)) 4585 4586 /* kill */ 4587 CHECK_OFFSET(si_pid); 4588 CHECK_OFFSET(si_uid); 4589 4590 /* timer */ 4591 CHECK_OFFSET(si_tid); 4592 CHECK_OFFSET(si_overrun); 4593 CHECK_OFFSET(si_value); 4594 4595 /* rt */ 4596 CHECK_OFFSET(si_pid); 4597 CHECK_OFFSET(si_uid); 4598 CHECK_OFFSET(si_value); 4599 4600 /* sigchld */ 4601 CHECK_OFFSET(si_pid); 4602 CHECK_OFFSET(si_uid); 4603 CHECK_OFFSET(si_status); 4604 CHECK_OFFSET(si_utime); 4605 CHECK_OFFSET(si_stime); 4606 4607 /* sigfault */ 4608 CHECK_OFFSET(si_addr); 4609 CHECK_OFFSET(si_trapno); 4610 CHECK_OFFSET(si_addr_lsb); 4611 CHECK_OFFSET(si_lower); 4612 CHECK_OFFSET(si_upper); 4613 CHECK_OFFSET(si_pkey); 4614 CHECK_OFFSET(si_perf_data); 4615 CHECK_OFFSET(si_perf_type); 4616 4617 /* sigpoll */ 4618 CHECK_OFFSET(si_band); 4619 CHECK_OFFSET(si_fd); 4620 4621 /* sigsys */ 4622 CHECK_OFFSET(si_call_addr); 4623 CHECK_OFFSET(si_syscall); 4624 CHECK_OFFSET(si_arch); 4625 #undef CHECK_OFFSET 4626 4627 /* usb asyncio */ 4628 BUILD_BUG_ON(offsetof(struct siginfo, si_pid) != 4629 offsetof(struct siginfo, si_addr)); 4630 if (sizeof(int) == sizeof(void __user *)) { 4631 BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) != 4632 sizeof(void __user *)); 4633 } else { 4634 BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) + 4635 sizeof_field(struct siginfo, si_uid)) != 4636 sizeof(void __user *)); 4637 BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) != 4638 offsetof(struct siginfo, si_uid)); 4639 } 4640 #ifdef CONFIG_COMPAT 4641 BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) != 4642 offsetof(struct compat_siginfo, si_addr)); 4643 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) != 4644 sizeof(compat_uptr_t)); 4645 BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) != 4646 sizeof_field(struct siginfo, si_pid)); 4647 #endif 4648 } 4649 4650 void __init signals_init(void) 4651 { 4652 siginfo_buildtime_checks(); 4653 4654 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC); 4655 } 4656 4657 #ifdef CONFIG_KGDB_KDB 4658 #include <linux/kdb.h> 4659 /* 4660 * kdb_send_sig - Allows kdb to send signals without exposing 4661 * signal internals. This function checks if the required locks are 4662 * available before calling the main signal code, to avoid kdb 4663 * deadlocks. 4664 */ 4665 void kdb_send_sig(struct task_struct *t, int sig) 4666 { 4667 static struct task_struct *kdb_prev_t; 4668 int new_t, ret; 4669 if (!spin_trylock(&t->sighand->siglock)) { 4670 kdb_printf("Can't do kill command now.\n" 4671 "The sigmask lock is held somewhere else in " 4672 "kernel, try again later\n"); 4673 return; 4674 } 4675 new_t = kdb_prev_t != t; 4676 kdb_prev_t = t; 4677 if (!task_is_running(t) && new_t) { 4678 spin_unlock(&t->sighand->siglock); 4679 kdb_printf("Process is not RUNNING, sending a signal from " 4680 "kdb risks deadlock\n" 4681 "on the run queue locks. " 4682 "The signal has _not_ been sent.\n" 4683 "Reissue the kill command if you want to risk " 4684 "the deadlock.\n"); 4685 return; 4686 } 4687 ret = send_signal(sig, SEND_SIG_PRIV, t, PIDTYPE_PID); 4688 spin_unlock(&t->sighand->siglock); 4689 if (ret) 4690 kdb_printf("Fail to deliver Signal %d to process %d.\n", 4691 sig, t->pid); 4692 else 4693 kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid); 4694 } 4695 #endif /* CONFIG_KGDB_KDB */ 4696