| 1 | // SPDX-License-Identifier: GPL-2.0-only |
| 2 | /* |
| 3 | * linux/kernel/exit.c |
| 4 | * |
| 5 | * Copyright (C) 1991, 1992 Linus Torvalds |
| 6 | */ |
| 7 | |
| 8 | #include <linux/mm.h> |
| 9 | #include <linux/slab.h> |
| 10 | #include <linux/sched/autogroup.h> |
| 11 | #include <linux/sched/mm.h> |
| 12 | #include <linux/sched/stat.h> |
| 13 | #include <linux/sched/task.h> |
| 14 | #include <linux/sched/task_stack.h> |
| 15 | #include <linux/sched/cputime.h> |
| 16 | #include <linux/interrupt.h> |
| 17 | #include <linux/module.h> |
| 18 | #include <linux/capability.h> |
| 19 | #include <linux/completion.h> |
| 20 | #include <linux/personality.h> |
| 21 | #include <linux/tty.h> |
| 22 | #include <linux/iocontext.h> |
| 23 | #include <linux/key.h> |
| 24 | #include <linux/cpu.h> |
| 25 | #include <linux/acct.h> |
| 26 | #include <linux/tsacct_kern.h> |
| 27 | #include <linux/file.h> |
| 28 | #include <linux/fdtable.h> |
| 29 | #include <linux/freezer.h> |
| 30 | #include <linux/binfmts.h> |
| 31 | #include <linux/nsproxy.h> |
| 32 | #include <linux/pid_namespace.h> |
| 33 | #include <linux/ptrace.h> |
| 34 | #include <linux/profile.h> |
| 35 | #include <linux/mount.h> |
| 36 | #include <linux/proc_fs.h> |
| 37 | #include <linux/kthread.h> |
| 38 | #include <linux/mempolicy.h> |
| 39 | #include <linux/taskstats_kern.h> |
| 40 | #include <linux/delayacct.h> |
| 41 | #include <linux/cgroup.h> |
| 42 | #include <linux/syscalls.h> |
| 43 | #include <linux/signal.h> |
| 44 | #include <linux/posix-timers.h> |
| 45 | #include <linux/cn_proc.h> |
| 46 | #include <linux/mutex.h> |
| 47 | #include <linux/futex.h> |
| 48 | #include <linux/pipe_fs_i.h> |
| 49 | #include <linux/audit.h> /* for audit_free() */ |
| 50 | #include <linux/resource.h> |
| 51 | #include <linux/task_io_accounting_ops.h> |
| 52 | #include <linux/blkdev.h> |
| 53 | #include <linux/task_work.h> |
| 54 | #include <linux/fs_struct.h> |
| 55 | #include <linux/init_task.h> |
| 56 | #include <linux/perf_event.h> |
| 57 | #include <trace/events/sched.h> |
| 58 | #include <linux/hw_breakpoint.h> |
| 59 | #include <linux/oom.h> |
| 60 | #include <linux/writeback.h> |
| 61 | #include <linux/shm.h> |
| 62 | #include <linux/kcov.h> |
| 63 | #include <linux/kmsan.h> |
| 64 | #include <linux/random.h> |
| 65 | #include <linux/rcuwait.h> |
| 66 | #include <linux/compat.h> |
| 67 | #include <linux/io_uring.h> |
| 68 | #include <linux/kprobes.h> |
| 69 | #include <linux/rethook.h> |
| 70 | #include <linux/sysfs.h> |
| 71 | #include <linux/user_events.h> |
| 72 | |
| 73 | #include <linux/uaccess.h> |
| 74 | #include <asm/unistd.h> |
| 75 | #include <asm/mmu_context.h> |
| 76 | |
| 77 | /* |
| 78 | * The default value should be high enough to not crash a system that randomly |
| 79 | * crashes its kernel from time to time, but low enough to at least not permit |
| 80 | * overflowing 32-bit refcounts or the ldsem writer count. |
| 81 | */ |
| 82 | static unsigned int oops_limit = 10000; |
| 83 | |
| 84 | #ifdef CONFIG_SYSCTL |
| 85 | static struct ctl_table kern_exit_table[] = { |
| 86 | { |
| 87 | .procname = "oops_limit", |
| 88 | .data = &oops_limit, |
| 89 | .maxlen = sizeof(oops_limit), |
| 90 | .mode = 0644, |
| 91 | .proc_handler = proc_douintvec, |
| 92 | }, |
| 93 | { } |
| 94 | }; |
| 95 | |
| 96 | static __init int kernel_exit_sysctls_init(void) |
| 97 | { |
| 98 | register_sysctl_init("kernel", kern_exit_table); |
| 99 | return 0; |
| 100 | } |
| 101 | late_initcall(kernel_exit_sysctls_init); |
| 102 | #endif |
| 103 | |
| 104 | static atomic_t oops_count = ATOMIC_INIT(0); |
| 105 | |
| 106 | #ifdef CONFIG_SYSFS |
| 107 | static ssize_t oops_count_show(struct kobject *kobj, struct kobj_attribute *attr, |
| 108 | char *page) |
| 109 | { |
| 110 | return sysfs_emit(page, "%d\n", atomic_read(&oops_count)); |
| 111 | } |
| 112 | |
| 113 | static struct kobj_attribute oops_count_attr = __ATTR_RO(oops_count); |
| 114 | |
| 115 | static __init int kernel_exit_sysfs_init(void) |
| 116 | { |
| 117 | sysfs_add_file_to_group(kernel_kobj, &oops_count_attr.attr, NULL); |
| 118 | return 0; |
| 119 | } |
| 120 | late_initcall(kernel_exit_sysfs_init); |
| 121 | #endif |
| 122 | |
| 123 | static void __unhash_process(struct task_struct *p, bool group_dead) |
| 124 | { |
| 125 | nr_threads--; |
| 126 | detach_pid(p, PIDTYPE_PID); |
| 127 | if (group_dead) { |
| 128 | detach_pid(p, PIDTYPE_TGID); |
| 129 | detach_pid(p, PIDTYPE_PGID); |
| 130 | detach_pid(p, PIDTYPE_SID); |
| 131 | |
| 132 | list_del_rcu(&p->tasks); |
| 133 | list_del_init(&p->sibling); |
| 134 | __this_cpu_dec(process_counts); |
| 135 | } |
| 136 | list_del_rcu(&p->thread_group); |
| 137 | list_del_rcu(&p->thread_node); |
| 138 | } |
| 139 | |
| 140 | /* |
| 141 | * This function expects the tasklist_lock write-locked. |
| 142 | */ |
| 143 | static void __exit_signal(struct task_struct *tsk) |
| 144 | { |
| 145 | struct signal_struct *sig = tsk->signal; |
| 146 | bool group_dead = thread_group_leader(tsk); |
| 147 | struct sighand_struct *sighand; |
| 148 | struct tty_struct *tty; |
| 149 | u64 utime, stime; |
| 150 | |
| 151 | sighand = rcu_dereference_check(tsk->sighand, |
| 152 | lockdep_tasklist_lock_is_held()); |
| 153 | spin_lock(&sighand->siglock); |
| 154 | |
| 155 | #ifdef CONFIG_POSIX_TIMERS |
| 156 | posix_cpu_timers_exit(tsk); |
| 157 | if (group_dead) |
| 158 | posix_cpu_timers_exit_group(tsk); |
| 159 | #endif |
| 160 | |
| 161 | if (group_dead) { |
| 162 | tty = sig->tty; |
| 163 | sig->tty = NULL; |
| 164 | } else { |
| 165 | /* |
| 166 | * If there is any task waiting for the group exit |
| 167 | * then notify it: |
| 168 | */ |
| 169 | if (sig->notify_count > 0 && !--sig->notify_count) |
| 170 | wake_up_process(sig->group_exec_task); |
| 171 | |
| 172 | if (tsk == sig->curr_target) |
| 173 | sig->curr_target = next_thread(tsk); |
| 174 | } |
| 175 | |
| 176 | add_device_randomness((const void*) &tsk->se.sum_exec_runtime, |
| 177 | sizeof(unsigned long long)); |
| 178 | |
| 179 | /* |
| 180 | * Accumulate here the counters for all threads as they die. We could |
| 181 | * skip the group leader because it is the last user of signal_struct, |
| 182 | * but we want to avoid the race with thread_group_cputime() which can |
| 183 | * see the empty ->thread_head list. |
| 184 | */ |
| 185 | task_cputime(tsk, &utime, &stime); |
| 186 | write_seqlock(&sig->stats_lock); |
| 187 | sig->utime += utime; |
| 188 | sig->stime += stime; |
| 189 | sig->gtime += task_gtime(tsk); |
| 190 | sig->min_flt += tsk->min_flt; |
| 191 | sig->maj_flt += tsk->maj_flt; |
| 192 | sig->nvcsw += tsk->nvcsw; |
| 193 | sig->nivcsw += tsk->nivcsw; |
| 194 | sig->inblock += task_io_get_inblock(tsk); |
| 195 | sig->oublock += task_io_get_oublock(tsk); |
| 196 | task_io_accounting_add(&sig->ioac, &tsk->ioac); |
| 197 | sig->sum_sched_runtime += tsk->se.sum_exec_runtime; |
| 198 | sig->nr_threads--; |
| 199 | __unhash_process(tsk, group_dead); |
| 200 | write_sequnlock(&sig->stats_lock); |
| 201 | |
| 202 | /* |
| 203 | * Do this under ->siglock, we can race with another thread |
| 204 | * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. |
| 205 | */ |
| 206 | flush_sigqueue(&tsk->pending); |
| 207 | tsk->sighand = NULL; |
| 208 | spin_unlock(&sighand->siglock); |
| 209 | |
| 210 | __cleanup_sighand(sighand); |
| 211 | clear_tsk_thread_flag(tsk, TIF_SIGPENDING); |
| 212 | if (group_dead) { |
| 213 | flush_sigqueue(&sig->shared_pending); |
| 214 | tty_kref_put(tty); |
| 215 | } |
| 216 | } |
| 217 | |
| 218 | static void delayed_put_task_struct(struct rcu_head *rhp) |
| 219 | { |
| 220 | struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); |
| 221 | |
| 222 | kprobe_flush_task(tsk); |
| 223 | rethook_flush_task(tsk); |
| 224 | perf_event_delayed_put(tsk); |
| 225 | trace_sched_process_free(tsk); |
| 226 | put_task_struct(tsk); |
| 227 | } |
| 228 | |
| 229 | void put_task_struct_rcu_user(struct task_struct *task) |
| 230 | { |
| 231 | if (refcount_dec_and_test(&task->rcu_users)) |
| 232 | call_rcu(&task->rcu, delayed_put_task_struct); |
| 233 | } |
| 234 | |
| 235 | void __weak release_thread(struct task_struct *dead_task) |
| 236 | { |
| 237 | } |
| 238 | |
| 239 | void release_task(struct task_struct *p) |
| 240 | { |
| 241 | struct task_struct *leader; |
| 242 | struct pid *thread_pid; |
| 243 | int zap_leader; |
| 244 | repeat: |
| 245 | /* don't need to get the RCU readlock here - the process is dead and |
| 246 | * can't be modifying its own credentials. But shut RCU-lockdep up */ |
| 247 | rcu_read_lock(); |
| 248 | dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); |
| 249 | rcu_read_unlock(); |
| 250 | |
| 251 | cgroup_release(p); |
| 252 | |
| 253 | write_lock_irq(&tasklist_lock); |
| 254 | ptrace_release_task(p); |
| 255 | thread_pid = get_pid(p->thread_pid); |
| 256 | __exit_signal(p); |
| 257 | |
| 258 | /* |
| 259 | * If we are the last non-leader member of the thread |
| 260 | * group, and the leader is zombie, then notify the |
| 261 | * group leader's parent process. (if it wants notification.) |
| 262 | */ |
| 263 | zap_leader = 0; |
| 264 | leader = p->group_leader; |
| 265 | if (leader != p && thread_group_empty(leader) |
| 266 | && leader->exit_state == EXIT_ZOMBIE) { |
| 267 | /* |
| 268 | * If we were the last child thread and the leader has |
| 269 | * exited already, and the leader's parent ignores SIGCHLD, |
| 270 | * then we are the one who should release the leader. |
| 271 | */ |
| 272 | zap_leader = do_notify_parent(leader, leader->exit_signal); |
| 273 | if (zap_leader) |
| 274 | leader->exit_state = EXIT_DEAD; |
| 275 | } |
| 276 | |
| 277 | write_unlock_irq(&tasklist_lock); |
| 278 | seccomp_filter_release(p); |
| 279 | proc_flush_pid(thread_pid); |
| 280 | put_pid(thread_pid); |
| 281 | release_thread(p); |
| 282 | put_task_struct_rcu_user(p); |
| 283 | |
| 284 | p = leader; |
| 285 | if (unlikely(zap_leader)) |
| 286 | goto repeat; |
| 287 | } |
| 288 | |
| 289 | int rcuwait_wake_up(struct rcuwait *w) |
| 290 | { |
| 291 | int ret = 0; |
| 292 | struct task_struct *task; |
| 293 | |
| 294 | rcu_read_lock(); |
| 295 | |
| 296 | /* |
| 297 | * Order condition vs @task, such that everything prior to the load |
| 298 | * of @task is visible. This is the condition as to why the user called |
| 299 | * rcuwait_wake() in the first place. Pairs with set_current_state() |
| 300 | * barrier (A) in rcuwait_wait_event(). |
| 301 | * |
| 302 | * WAIT WAKE |
| 303 | * [S] tsk = current [S] cond = true |
| 304 | * MB (A) MB (B) |
| 305 | * [L] cond [L] tsk |
| 306 | */ |
| 307 | smp_mb(); /* (B) */ |
| 308 | |
| 309 | task = rcu_dereference(w->task); |
| 310 | if (task) |
| 311 | ret = wake_up_process(task); |
| 312 | rcu_read_unlock(); |
| 313 | |
| 314 | return ret; |
| 315 | } |
| 316 | EXPORT_SYMBOL_GPL(rcuwait_wake_up); |
| 317 | |
| 318 | /* |
| 319 | * Determine if a process group is "orphaned", according to the POSIX |
| 320 | * definition in 2.2.2.52. Orphaned process groups are not to be affected |
| 321 | * by terminal-generated stop signals. Newly orphaned process groups are |
| 322 | * to receive a SIGHUP and a SIGCONT. |
| 323 | * |
| 324 | * "I ask you, have you ever known what it is to be an orphan?" |
| 325 | */ |
| 326 | static int will_become_orphaned_pgrp(struct pid *pgrp, |
| 327 | struct task_struct *ignored_task) |
| 328 | { |
| 329 | struct task_struct *p; |
| 330 | |
| 331 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
| 332 | if ((p == ignored_task) || |
| 333 | (p->exit_state && thread_group_empty(p)) || |
| 334 | is_global_init(p->real_parent)) |
| 335 | continue; |
| 336 | |
| 337 | if (task_pgrp(p->real_parent) != pgrp && |
| 338 | task_session(p->real_parent) == task_session(p)) |
| 339 | return 0; |
| 340 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
| 341 | |
| 342 | return 1; |
| 343 | } |
| 344 | |
| 345 | int is_current_pgrp_orphaned(void) |
| 346 | { |
| 347 | int retval; |
| 348 | |
| 349 | read_lock(&tasklist_lock); |
| 350 | retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); |
| 351 | read_unlock(&tasklist_lock); |
| 352 | |
| 353 | return retval; |
| 354 | } |
| 355 | |
| 356 | static bool has_stopped_jobs(struct pid *pgrp) |
| 357 | { |
| 358 | struct task_struct *p; |
| 359 | |
| 360 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
| 361 | if (p->signal->flags & SIGNAL_STOP_STOPPED) |
| 362 | return true; |
| 363 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
| 364 | |
| 365 | return false; |
| 366 | } |
| 367 | |
| 368 | /* |
| 369 | * Check to see if any process groups have become orphaned as |
| 370 | * a result of our exiting, and if they have any stopped jobs, |
| 371 | * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) |
| 372 | */ |
| 373 | static void |
| 374 | kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) |
| 375 | { |
| 376 | struct pid *pgrp = task_pgrp(tsk); |
| 377 | struct task_struct *ignored_task = tsk; |
| 378 | |
| 379 | if (!parent) |
| 380 | /* exit: our father is in a different pgrp than |
| 381 | * we are and we were the only connection outside. |
| 382 | */ |
| 383 | parent = tsk->real_parent; |
| 384 | else |
| 385 | /* reparent: our child is in a different pgrp than |
| 386 | * we are, and it was the only connection outside. |
| 387 | */ |
| 388 | ignored_task = NULL; |
| 389 | |
| 390 | if (task_pgrp(parent) != pgrp && |
| 391 | task_session(parent) == task_session(tsk) && |
| 392 | will_become_orphaned_pgrp(pgrp, ignored_task) && |
| 393 | has_stopped_jobs(pgrp)) { |
| 394 | __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); |
| 395 | __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); |
| 396 | } |
| 397 | } |
| 398 | |
| 399 | static void coredump_task_exit(struct task_struct *tsk) |
| 400 | { |
| 401 | struct core_state *core_state; |
| 402 | |
| 403 | /* |
| 404 | * Serialize with any possible pending coredump. |
| 405 | * We must hold siglock around checking core_state |
| 406 | * and setting PF_POSTCOREDUMP. The core-inducing thread |
| 407 | * will increment ->nr_threads for each thread in the |
| 408 | * group without PF_POSTCOREDUMP set. |
| 409 | */ |
| 410 | spin_lock_irq(&tsk->sighand->siglock); |
| 411 | tsk->flags |= PF_POSTCOREDUMP; |
| 412 | core_state = tsk->signal->core_state; |
| 413 | spin_unlock_irq(&tsk->sighand->siglock); |
| 414 | |
| 415 | /* The vhost_worker does not particpate in coredumps */ |
| 416 | if (core_state && |
| 417 | ((tsk->flags & (PF_IO_WORKER | PF_USER_WORKER)) != PF_USER_WORKER)) { |
| 418 | struct core_thread self; |
| 419 | |
| 420 | self.task = current; |
| 421 | if (self.task->flags & PF_SIGNALED) |
| 422 | self.next = xchg(&core_state->dumper.next, &self); |
| 423 | else |
| 424 | self.task = NULL; |
| 425 | /* |
| 426 | * Implies mb(), the result of xchg() must be visible |
| 427 | * to core_state->dumper. |
| 428 | */ |
| 429 | if (atomic_dec_and_test(&core_state->nr_threads)) |
| 430 | complete(&core_state->startup); |
| 431 | |
| 432 | for (;;) { |
| 433 | set_current_state(TASK_UNINTERRUPTIBLE|TASK_FREEZABLE); |
| 434 | if (!self.task) /* see coredump_finish() */ |
| 435 | break; |
| 436 | schedule(); |
| 437 | } |
| 438 | __set_current_state(TASK_RUNNING); |
| 439 | } |
| 440 | } |
| 441 | |
| 442 | #ifdef CONFIG_MEMCG |
| 443 | /* |
| 444 | * A task is exiting. If it owned this mm, find a new owner for the mm. |
| 445 | */ |
| 446 | void mm_update_next_owner(struct mm_struct *mm) |
| 447 | { |
| 448 | struct task_struct *c, *g, *p = current; |
| 449 | |
| 450 | retry: |
| 451 | /* |
| 452 | * If the exiting or execing task is not the owner, it's |
| 453 | * someone else's problem. |
| 454 | */ |
| 455 | if (mm->owner != p) |
| 456 | return; |
| 457 | /* |
| 458 | * The current owner is exiting/execing and there are no other |
| 459 | * candidates. Do not leave the mm pointing to a possibly |
| 460 | * freed task structure. |
| 461 | */ |
| 462 | if (atomic_read(&mm->mm_users) <= 1) { |
| 463 | WRITE_ONCE(mm->owner, NULL); |
| 464 | return; |
| 465 | } |
| 466 | |
| 467 | read_lock(&tasklist_lock); |
| 468 | /* |
| 469 | * Search in the children |
| 470 | */ |
| 471 | list_for_each_entry(c, &p->children, sibling) { |
| 472 | if (c->mm == mm) |
| 473 | goto assign_new_owner; |
| 474 | } |
| 475 | |
| 476 | /* |
| 477 | * Search in the siblings |
| 478 | */ |
| 479 | list_for_each_entry(c, &p->real_parent->children, sibling) { |
| 480 | if (c->mm == mm) |
| 481 | goto assign_new_owner; |
| 482 | } |
| 483 | |
| 484 | /* |
| 485 | * Search through everything else, we should not get here often. |
| 486 | */ |
| 487 | for_each_process(g) { |
| 488 | if (g->flags & PF_KTHREAD) |
| 489 | continue; |
| 490 | for_each_thread(g, c) { |
| 491 | if (c->mm == mm) |
| 492 | goto assign_new_owner; |
| 493 | if (c->mm) |
| 494 | break; |
| 495 | } |
| 496 | } |
| 497 | read_unlock(&tasklist_lock); |
| 498 | /* |
| 499 | * We found no owner yet mm_users > 1: this implies that we are |
| 500 | * most likely racing with swapoff (try_to_unuse()) or /proc or |
| 501 | * ptrace or page migration (get_task_mm()). Mark owner as NULL. |
| 502 | */ |
| 503 | WRITE_ONCE(mm->owner, NULL); |
| 504 | return; |
| 505 | |
| 506 | assign_new_owner: |
| 507 | BUG_ON(c == p); |
| 508 | get_task_struct(c); |
| 509 | /* |
| 510 | * The task_lock protects c->mm from changing. |
| 511 | * We always want mm->owner->mm == mm |
| 512 | */ |
| 513 | task_lock(c); |
| 514 | /* |
| 515 | * Delay read_unlock() till we have the task_lock() |
| 516 | * to ensure that c does not slip away underneath us |
| 517 | */ |
| 518 | read_unlock(&tasklist_lock); |
| 519 | if (c->mm != mm) { |
| 520 | task_unlock(c); |
| 521 | put_task_struct(c); |
| 522 | goto retry; |
| 523 | } |
| 524 | WRITE_ONCE(mm->owner, c); |
| 525 | lru_gen_migrate_mm(mm); |
| 526 | task_unlock(c); |
| 527 | put_task_struct(c); |
| 528 | } |
| 529 | #endif /* CONFIG_MEMCG */ |
| 530 | |
| 531 | /* |
| 532 | * Turn us into a lazy TLB process if we |
| 533 | * aren't already.. |
| 534 | */ |
| 535 | static void exit_mm(void) |
| 536 | { |
| 537 | struct mm_struct *mm = current->mm; |
| 538 | |
| 539 | exit_mm_release(current, mm); |
| 540 | if (!mm) |
| 541 | return; |
| 542 | sync_mm_rss(mm); |
| 543 | mmap_read_lock(mm); |
| 544 | mmgrab_lazy_tlb(mm); |
| 545 | BUG_ON(mm != current->active_mm); |
| 546 | /* more a memory barrier than a real lock */ |
| 547 | task_lock(current); |
| 548 | /* |
| 549 | * When a thread stops operating on an address space, the loop |
| 550 | * in membarrier_private_expedited() may not observe that |
| 551 | * tsk->mm, and the loop in membarrier_global_expedited() may |
| 552 | * not observe a MEMBARRIER_STATE_GLOBAL_EXPEDITED |
| 553 | * rq->membarrier_state, so those would not issue an IPI. |
| 554 | * Membarrier requires a memory barrier after accessing |
| 555 | * user-space memory, before clearing tsk->mm or the |
| 556 | * rq->membarrier_state. |
| 557 | */ |
| 558 | smp_mb__after_spinlock(); |
| 559 | local_irq_disable(); |
| 560 | current->mm = NULL; |
| 561 | membarrier_update_current_mm(NULL); |
| 562 | enter_lazy_tlb(mm, current); |
| 563 | local_irq_enable(); |
| 564 | task_unlock(current); |
| 565 | mmap_read_unlock(mm); |
| 566 | mm_update_next_owner(mm); |
| 567 | mmput(mm); |
| 568 | if (test_thread_flag(TIF_MEMDIE)) |
| 569 | exit_oom_victim(); |
| 570 | } |
| 571 | |
| 572 | static struct task_struct *find_alive_thread(struct task_struct *p) |
| 573 | { |
| 574 | struct task_struct *t; |
| 575 | |
| 576 | for_each_thread(p, t) { |
| 577 | if (!(t->flags & PF_EXITING)) |
| 578 | return t; |
| 579 | } |
| 580 | return NULL; |
| 581 | } |
| 582 | |
| 583 | static struct task_struct *find_child_reaper(struct task_struct *father, |
| 584 | struct list_head *dead) |
| 585 | __releases(&tasklist_lock) |
| 586 | __acquires(&tasklist_lock) |
| 587 | { |
| 588 | struct pid_namespace *pid_ns = task_active_pid_ns(father); |
| 589 | struct task_struct *reaper = pid_ns->child_reaper; |
| 590 | struct task_struct *p, *n; |
| 591 | |
| 592 | if (likely(reaper != father)) |
| 593 | return reaper; |
| 594 | |
| 595 | reaper = find_alive_thread(father); |
| 596 | if (reaper) { |
| 597 | pid_ns->child_reaper = reaper; |
| 598 | return reaper; |
| 599 | } |
| 600 | |
| 601 | write_unlock_irq(&tasklist_lock); |
| 602 | |
| 603 | list_for_each_entry_safe(p, n, dead, ptrace_entry) { |
| 604 | list_del_init(&p->ptrace_entry); |
| 605 | release_task(p); |
| 606 | } |
| 607 | |
| 608 | zap_pid_ns_processes(pid_ns); |
| 609 | write_lock_irq(&tasklist_lock); |
| 610 | |
| 611 | return father; |
| 612 | } |
| 613 | |
| 614 | /* |
| 615 | * When we die, we re-parent all our children, and try to: |
| 616 | * 1. give them to another thread in our thread group, if such a member exists |
| 617 | * 2. give it to the first ancestor process which prctl'd itself as a |
| 618 | * child_subreaper for its children (like a service manager) |
| 619 | * 3. give it to the init process (PID 1) in our pid namespace |
| 620 | */ |
| 621 | static struct task_struct *find_new_reaper(struct task_struct *father, |
| 622 | struct task_struct *child_reaper) |
| 623 | { |
| 624 | struct task_struct *thread, *reaper; |
| 625 | |
| 626 | thread = find_alive_thread(father); |
| 627 | if (thread) |
| 628 | return thread; |
| 629 | |
| 630 | if (father->signal->has_child_subreaper) { |
| 631 | unsigned int ns_level = task_pid(father)->level; |
| 632 | /* |
| 633 | * Find the first ->is_child_subreaper ancestor in our pid_ns. |
| 634 | * We can't check reaper != child_reaper to ensure we do not |
| 635 | * cross the namespaces, the exiting parent could be injected |
| 636 | * by setns() + fork(). |
| 637 | * We check pid->level, this is slightly more efficient than |
| 638 | * task_active_pid_ns(reaper) != task_active_pid_ns(father). |
| 639 | */ |
| 640 | for (reaper = father->real_parent; |
| 641 | task_pid(reaper)->level == ns_level; |
| 642 | reaper = reaper->real_parent) { |
| 643 | if (reaper == &init_task) |
| 644 | break; |
| 645 | if (!reaper->signal->is_child_subreaper) |
| 646 | continue; |
| 647 | thread = find_alive_thread(reaper); |
| 648 | if (thread) |
| 649 | return thread; |
| 650 | } |
| 651 | } |
| 652 | |
| 653 | return child_reaper; |
| 654 | } |
| 655 | |
| 656 | /* |
| 657 | * Any that need to be release_task'd are put on the @dead list. |
| 658 | */ |
| 659 | static void reparent_leader(struct task_struct *father, struct task_struct *p, |
| 660 | struct list_head *dead) |
| 661 | { |
| 662 | if (unlikely(p->exit_state == EXIT_DEAD)) |
| 663 | return; |
| 664 | |
| 665 | /* We don't want people slaying init. */ |
| 666 | p->exit_signal = SIGCHLD; |
| 667 | |
| 668 | /* If it has exited notify the new parent about this child's death. */ |
| 669 | if (!p->ptrace && |
| 670 | p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { |
| 671 | if (do_notify_parent(p, p->exit_signal)) { |
| 672 | p->exit_state = EXIT_DEAD; |
| 673 | list_add(&p->ptrace_entry, dead); |
| 674 | } |
| 675 | } |
| 676 | |
| 677 | kill_orphaned_pgrp(p, father); |
| 678 | } |
| 679 | |
| 680 | /* |
| 681 | * This does two things: |
| 682 | * |
| 683 | * A. Make init inherit all the child processes |
| 684 | * B. Check to see if any process groups have become orphaned |
| 685 | * as a result of our exiting, and if they have any stopped |
| 686 | * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) |
| 687 | */ |
| 688 | static void forget_original_parent(struct task_struct *father, |
| 689 | struct list_head *dead) |
| 690 | { |
| 691 | struct task_struct *p, *t, *reaper; |
| 692 | |
| 693 | if (unlikely(!list_empty(&father->ptraced))) |
| 694 | exit_ptrace(father, dead); |
| 695 | |
| 696 | /* Can drop and reacquire tasklist_lock */ |
| 697 | reaper = find_child_reaper(father, dead); |
| 698 | if (list_empty(&father->children)) |
| 699 | return; |
| 700 | |
| 701 | reaper = find_new_reaper(father, reaper); |
| 702 | list_for_each_entry(p, &father->children, sibling) { |
| 703 | for_each_thread(p, t) { |
| 704 | RCU_INIT_POINTER(t->real_parent, reaper); |
| 705 | BUG_ON((!t->ptrace) != (rcu_access_pointer(t->parent) == father)); |
| 706 | if (likely(!t->ptrace)) |
| 707 | t->parent = t->real_parent; |
| 708 | if (t->pdeath_signal) |
| 709 | group_send_sig_info(t->pdeath_signal, |
| 710 | SEND_SIG_NOINFO, t, |
| 711 | PIDTYPE_TGID); |
| 712 | } |
| 713 | /* |
| 714 | * If this is a threaded reparent there is no need to |
| 715 | * notify anyone anything has happened. |
| 716 | */ |
| 717 | if (!same_thread_group(reaper, father)) |
| 718 | reparent_leader(father, p, dead); |
| 719 | } |
| 720 | list_splice_tail_init(&father->children, &reaper->children); |
| 721 | } |
| 722 | |
| 723 | /* |
| 724 | * Send signals to all our closest relatives so that they know |
| 725 | * to properly mourn us.. |
| 726 | */ |
| 727 | static void exit_notify(struct task_struct *tsk, int group_dead) |
| 728 | { |
| 729 | bool autoreap; |
| 730 | struct task_struct *p, *n; |
| 731 | LIST_HEAD(dead); |
| 732 | |
| 733 | write_lock_irq(&tasklist_lock); |
| 734 | forget_original_parent(tsk, &dead); |
| 735 | |
| 736 | if (group_dead) |
| 737 | kill_orphaned_pgrp(tsk->group_leader, NULL); |
| 738 | |
| 739 | tsk->exit_state = EXIT_ZOMBIE; |
| 740 | if (unlikely(tsk->ptrace)) { |
| 741 | int sig = thread_group_leader(tsk) && |
| 742 | thread_group_empty(tsk) && |
| 743 | !ptrace_reparented(tsk) ? |
| 744 | tsk->exit_signal : SIGCHLD; |
| 745 | autoreap = do_notify_parent(tsk, sig); |
| 746 | } else if (thread_group_leader(tsk)) { |
| 747 | autoreap = thread_group_empty(tsk) && |
| 748 | do_notify_parent(tsk, tsk->exit_signal); |
| 749 | } else { |
| 750 | autoreap = true; |
| 751 | } |
| 752 | |
| 753 | if (autoreap) { |
| 754 | tsk->exit_state = EXIT_DEAD; |
| 755 | list_add(&tsk->ptrace_entry, &dead); |
| 756 | } |
| 757 | |
| 758 | /* mt-exec, de_thread() is waiting for group leader */ |
| 759 | if (unlikely(tsk->signal->notify_count < 0)) |
| 760 | wake_up_process(tsk->signal->group_exec_task); |
| 761 | write_unlock_irq(&tasklist_lock); |
| 762 | |
| 763 | list_for_each_entry_safe(p, n, &dead, ptrace_entry) { |
| 764 | list_del_init(&p->ptrace_entry); |
| 765 | release_task(p); |
| 766 | } |
| 767 | } |
| 768 | |
| 769 | #ifdef CONFIG_DEBUG_STACK_USAGE |
| 770 | static void check_stack_usage(void) |
| 771 | { |
| 772 | static DEFINE_SPINLOCK(low_water_lock); |
| 773 | static int lowest_to_date = THREAD_SIZE; |
| 774 | unsigned long free; |
| 775 | |
| 776 | free = stack_not_used(current); |
| 777 | |
| 778 | if (free >= lowest_to_date) |
| 779 | return; |
| 780 | |
| 781 | spin_lock(&low_water_lock); |
| 782 | if (free < lowest_to_date) { |
| 783 | pr_info("%s (%d) used greatest stack depth: %lu bytes left\n", |
| 784 | current->comm, task_pid_nr(current), free); |
| 785 | lowest_to_date = free; |
| 786 | } |
| 787 | spin_unlock(&low_water_lock); |
| 788 | } |
| 789 | #else |
| 790 | static inline void check_stack_usage(void) {} |
| 791 | #endif |
| 792 | |
| 793 | static void synchronize_group_exit(struct task_struct *tsk, long code) |
| 794 | { |
| 795 | struct sighand_struct *sighand = tsk->sighand; |
| 796 | struct signal_struct *signal = tsk->signal; |
| 797 | |
| 798 | spin_lock_irq(&sighand->siglock); |
| 799 | signal->quick_threads--; |
| 800 | if ((signal->quick_threads == 0) && |
| 801 | !(signal->flags & SIGNAL_GROUP_EXIT)) { |
| 802 | signal->flags = SIGNAL_GROUP_EXIT; |
| 803 | signal->group_exit_code = code; |
| 804 | signal->group_stop_count = 0; |
| 805 | } |
| 806 | spin_unlock_irq(&sighand->siglock); |
| 807 | } |
| 808 | |
| 809 | void __noreturn do_exit(long code) |
| 810 | { |
| 811 | struct task_struct *tsk = current; |
| 812 | int group_dead; |
| 813 | |
| 814 | WARN_ON(irqs_disabled()); |
| 815 | |
| 816 | synchronize_group_exit(tsk, code); |
| 817 | |
| 818 | WARN_ON(tsk->plug); |
| 819 | |
| 820 | kcov_task_exit(tsk); |
| 821 | kmsan_task_exit(tsk); |
| 822 | |
| 823 | coredump_task_exit(tsk); |
| 824 | ptrace_event(PTRACE_EVENT_EXIT, code); |
| 825 | user_events_exit(tsk); |
| 826 | |
| 827 | validate_creds_for_do_exit(tsk); |
| 828 | |
| 829 | io_uring_files_cancel(); |
| 830 | exit_signals(tsk); /* sets PF_EXITING */ |
| 831 | |
| 832 | /* sync mm's RSS info before statistics gathering */ |
| 833 | if (tsk->mm) |
| 834 | sync_mm_rss(tsk->mm); |
| 835 | acct_update_integrals(tsk); |
| 836 | group_dead = atomic_dec_and_test(&tsk->signal->live); |
| 837 | if (group_dead) { |
| 838 | /* |
| 839 | * If the last thread of global init has exited, panic |
| 840 | * immediately to get a useable coredump. |
| 841 | */ |
| 842 | if (unlikely(is_global_init(tsk))) |
| 843 | panic("Attempted to kill init! exitcode=0x%08x\n", |
| 844 | tsk->signal->group_exit_code ?: (int)code); |
| 845 | |
| 846 | #ifdef CONFIG_POSIX_TIMERS |
| 847 | hrtimer_cancel(&tsk->signal->real_timer); |
| 848 | exit_itimers(tsk); |
| 849 | #endif |
| 850 | if (tsk->mm) |
| 851 | setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); |
| 852 | } |
| 853 | acct_collect(code, group_dead); |
| 854 | if (group_dead) |
| 855 | tty_audit_exit(); |
| 856 | audit_free(tsk); |
| 857 | |
| 858 | tsk->exit_code = code; |
| 859 | taskstats_exit(tsk, group_dead); |
| 860 | |
| 861 | exit_mm(); |
| 862 | |
| 863 | if (group_dead) |
| 864 | acct_process(); |
| 865 | trace_sched_process_exit(tsk); |
| 866 | |
| 867 | exit_sem(tsk); |
| 868 | exit_shm(tsk); |
| 869 | exit_files(tsk); |
| 870 | exit_fs(tsk); |
| 871 | if (group_dead) |
| 872 | disassociate_ctty(1); |
| 873 | exit_task_namespaces(tsk); |
| 874 | exit_task_work(tsk); |
| 875 | exit_thread(tsk); |
| 876 | |
| 877 | /* |
| 878 | * Flush inherited counters to the parent - before the parent |
| 879 | * gets woken up by child-exit notifications. |
| 880 | * |
| 881 | * because of cgroup mode, must be called before cgroup_exit() |
| 882 | */ |
| 883 | perf_event_exit_task(tsk); |
| 884 | |
| 885 | sched_autogroup_exit_task(tsk); |
| 886 | cgroup_exit(tsk); |
| 887 | |
| 888 | /* |
| 889 | * FIXME: do that only when needed, using sched_exit tracepoint |
| 890 | */ |
| 891 | flush_ptrace_hw_breakpoint(tsk); |
| 892 | |
| 893 | exit_tasks_rcu_start(); |
| 894 | exit_notify(tsk, group_dead); |
| 895 | proc_exit_connector(tsk); |
| 896 | mpol_put_task_policy(tsk); |
| 897 | #ifdef CONFIG_FUTEX |
| 898 | if (unlikely(current->pi_state_cache)) |
| 899 | kfree(current->pi_state_cache); |
| 900 | #endif |
| 901 | /* |
| 902 | * Make sure we are holding no locks: |
| 903 | */ |
| 904 | debug_check_no_locks_held(); |
| 905 | |
| 906 | if (tsk->io_context) |
| 907 | exit_io_context(tsk); |
| 908 | |
| 909 | if (tsk->splice_pipe) |
| 910 | free_pipe_info(tsk->splice_pipe); |
| 911 | |
| 912 | if (tsk->task_frag.page) |
| 913 | put_page(tsk->task_frag.page); |
| 914 | |
| 915 | validate_creds_for_do_exit(tsk); |
| 916 | exit_task_stack_account(tsk); |
| 917 | |
| 918 | check_stack_usage(); |
| 919 | preempt_disable(); |
| 920 | if (tsk->nr_dirtied) |
| 921 | __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); |
| 922 | exit_rcu(); |
| 923 | exit_tasks_rcu_finish(); |
| 924 | |
| 925 | lockdep_free_task(tsk); |
| 926 | do_task_dead(); |
| 927 | } |
| 928 | |
| 929 | void __noreturn make_task_dead(int signr) |
| 930 | { |
| 931 | /* |
| 932 | * Take the task off the cpu after something catastrophic has |
| 933 | * happened. |
| 934 | * |
| 935 | * We can get here from a kernel oops, sometimes with preemption off. |
| 936 | * Start by checking for critical errors. |
| 937 | * Then fix up important state like USER_DS and preemption. |
| 938 | * Then do everything else. |
| 939 | */ |
| 940 | struct task_struct *tsk = current; |
| 941 | unsigned int limit; |
| 942 | |
| 943 | if (unlikely(in_interrupt())) |
| 944 | panic("Aiee, killing interrupt handler!"); |
| 945 | if (unlikely(!tsk->pid)) |
| 946 | panic("Attempted to kill the idle task!"); |
| 947 | |
| 948 | if (unlikely(irqs_disabled())) { |
| 949 | pr_info("note: %s[%d] exited with irqs disabled\n", |
| 950 | current->comm, task_pid_nr(current)); |
| 951 | local_irq_enable(); |
| 952 | } |
| 953 | if (unlikely(in_atomic())) { |
| 954 | pr_info("note: %s[%d] exited with preempt_count %d\n", |
| 955 | current->comm, task_pid_nr(current), |
| 956 | preempt_count()); |
| 957 | preempt_count_set(PREEMPT_ENABLED); |
| 958 | } |
| 959 | |
| 960 | /* |
| 961 | * Every time the system oopses, if the oops happens while a reference |
| 962 | * to an object was held, the reference leaks. |
| 963 | * If the oops doesn't also leak memory, repeated oopsing can cause |
| 964 | * reference counters to wrap around (if they're not using refcount_t). |
| 965 | * This means that repeated oopsing can make unexploitable-looking bugs |
| 966 | * exploitable through repeated oopsing. |
| 967 | * To make sure this can't happen, place an upper bound on how often the |
| 968 | * kernel may oops without panic(). |
| 969 | */ |
| 970 | limit = READ_ONCE(oops_limit); |
| 971 | if (atomic_inc_return(&oops_count) >= limit && limit) |
| 972 | panic("Oopsed too often (kernel.oops_limit is %d)", limit); |
| 973 | |
| 974 | /* |
| 975 | * We're taking recursive faults here in make_task_dead. Safest is to just |
| 976 | * leave this task alone and wait for reboot. |
| 977 | */ |
| 978 | if (unlikely(tsk->flags & PF_EXITING)) { |
| 979 | pr_alert("Fixing recursive fault but reboot is needed!\n"); |
| 980 | futex_exit_recursive(tsk); |
| 981 | tsk->exit_state = EXIT_DEAD; |
| 982 | refcount_inc(&tsk->rcu_users); |
| 983 | do_task_dead(); |
| 984 | } |
| 985 | |
| 986 | do_exit(signr); |
| 987 | } |
| 988 | |
| 989 | SYSCALL_DEFINE1(exit, int, error_code) |
| 990 | { |
| 991 | do_exit((error_code&0xff)<<8); |
| 992 | } |
| 993 | |
| 994 | /* |
| 995 | * Take down every thread in the group. This is called by fatal signals |
| 996 | * as well as by sys_exit_group (below). |
| 997 | */ |
| 998 | void __noreturn |
| 999 | do_group_exit(int exit_code) |
| 1000 | { |
| 1001 | struct signal_struct *sig = current->signal; |
| 1002 | |
| 1003 | if (sig->flags & SIGNAL_GROUP_EXIT) |
| 1004 | exit_code = sig->group_exit_code; |
| 1005 | else if (sig->group_exec_task) |
| 1006 | exit_code = 0; |
| 1007 | else { |
| 1008 | struct sighand_struct *const sighand = current->sighand; |
| 1009 | |
| 1010 | spin_lock_irq(&sighand->siglock); |
| 1011 | if (sig->flags & SIGNAL_GROUP_EXIT) |
| 1012 | /* Another thread got here before we took the lock. */ |
| 1013 | exit_code = sig->group_exit_code; |
| 1014 | else if (sig->group_exec_task) |
| 1015 | exit_code = 0; |
| 1016 | else { |
| 1017 | sig->group_exit_code = exit_code; |
| 1018 | sig->flags = SIGNAL_GROUP_EXIT; |
| 1019 | zap_other_threads(current); |
| 1020 | } |
| 1021 | spin_unlock_irq(&sighand->siglock); |
| 1022 | } |
| 1023 | |
| 1024 | do_exit(exit_code); |
| 1025 | /* NOTREACHED */ |
| 1026 | } |
| 1027 | |
| 1028 | /* |
| 1029 | * this kills every thread in the thread group. Note that any externally |
| 1030 | * wait4()-ing process will get the correct exit code - even if this |
| 1031 | * thread is not the thread group leader. |
| 1032 | */ |
| 1033 | SYSCALL_DEFINE1(exit_group, int, error_code) |
| 1034 | { |
| 1035 | do_group_exit((error_code & 0xff) << 8); |
| 1036 | /* NOTREACHED */ |
| 1037 | return 0; |
| 1038 | } |
| 1039 | |
| 1040 | struct waitid_info { |
| 1041 | pid_t pid; |
| 1042 | uid_t uid; |
| 1043 | int status; |
| 1044 | int cause; |
| 1045 | }; |
| 1046 | |
| 1047 | struct wait_opts { |
| 1048 | enum pid_type wo_type; |
| 1049 | int wo_flags; |
| 1050 | struct pid *wo_pid; |
| 1051 | |
| 1052 | struct waitid_info *wo_info; |
| 1053 | int wo_stat; |
| 1054 | struct rusage *wo_rusage; |
| 1055 | |
| 1056 | wait_queue_entry_t child_wait; |
| 1057 | int notask_error; |
| 1058 | }; |
| 1059 | |
| 1060 | static int eligible_pid(struct wait_opts *wo, struct task_struct *p) |
| 1061 | { |
| 1062 | return wo->wo_type == PIDTYPE_MAX || |
| 1063 | task_pid_type(p, wo->wo_type) == wo->wo_pid; |
| 1064 | } |
| 1065 | |
| 1066 | static int |
| 1067 | eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p) |
| 1068 | { |
| 1069 | if (!eligible_pid(wo, p)) |
| 1070 | return 0; |
| 1071 | |
| 1072 | /* |
| 1073 | * Wait for all children (clone and not) if __WALL is set or |
| 1074 | * if it is traced by us. |
| 1075 | */ |
| 1076 | if (ptrace || (wo->wo_flags & __WALL)) |
| 1077 | return 1; |
| 1078 | |
| 1079 | /* |
| 1080 | * Otherwise, wait for clone children *only* if __WCLONE is set; |
| 1081 | * otherwise, wait for non-clone children *only*. |
| 1082 | * |
| 1083 | * Note: a "clone" child here is one that reports to its parent |
| 1084 | * using a signal other than SIGCHLD, or a non-leader thread which |
| 1085 | * we can only see if it is traced by us. |
| 1086 | */ |
| 1087 | if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) |
| 1088 | return 0; |
| 1089 | |
| 1090 | return 1; |
| 1091 | } |
| 1092 | |
| 1093 | /* |
| 1094 | * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold |
| 1095 | * read_lock(&tasklist_lock) on entry. If we return zero, we still hold |
| 1096 | * the lock and this task is uninteresting. If we return nonzero, we have |
| 1097 | * released the lock and the system call should return. |
| 1098 | */ |
| 1099 | static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) |
| 1100 | { |
| 1101 | int state, status; |
| 1102 | pid_t pid = task_pid_vnr(p); |
| 1103 | uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
| 1104 | struct waitid_info *infop; |
| 1105 | |
| 1106 | if (!likely(wo->wo_flags & WEXITED)) |
| 1107 | return 0; |
| 1108 | |
| 1109 | if (unlikely(wo->wo_flags & WNOWAIT)) { |
| 1110 | status = (p->signal->flags & SIGNAL_GROUP_EXIT) |
| 1111 | ? p->signal->group_exit_code : p->exit_code; |
| 1112 | get_task_struct(p); |
| 1113 | read_unlock(&tasklist_lock); |
| 1114 | sched_annotate_sleep(); |
| 1115 | if (wo->wo_rusage) |
| 1116 | getrusage(p, RUSAGE_BOTH, wo->wo_rusage); |
| 1117 | put_task_struct(p); |
| 1118 | goto out_info; |
| 1119 | } |
| 1120 | /* |
| 1121 | * Move the task's state to DEAD/TRACE, only one thread can do this. |
| 1122 | */ |
| 1123 | state = (ptrace_reparented(p) && thread_group_leader(p)) ? |
| 1124 | EXIT_TRACE : EXIT_DEAD; |
| 1125 | if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) |
| 1126 | return 0; |
| 1127 | /* |
| 1128 | * We own this thread, nobody else can reap it. |
| 1129 | */ |
| 1130 | read_unlock(&tasklist_lock); |
| 1131 | sched_annotate_sleep(); |
| 1132 | |
| 1133 | /* |
| 1134 | * Check thread_group_leader() to exclude the traced sub-threads. |
| 1135 | */ |
| 1136 | if (state == EXIT_DEAD && thread_group_leader(p)) { |
| 1137 | struct signal_struct *sig = p->signal; |
| 1138 | struct signal_struct *psig = current->signal; |
| 1139 | unsigned long maxrss; |
| 1140 | u64 tgutime, tgstime; |
| 1141 | |
| 1142 | /* |
| 1143 | * The resource counters for the group leader are in its |
| 1144 | * own task_struct. Those for dead threads in the group |
| 1145 | * are in its signal_struct, as are those for the child |
| 1146 | * processes it has previously reaped. All these |
| 1147 | * accumulate in the parent's signal_struct c* fields. |
| 1148 | * |
| 1149 | * We don't bother to take a lock here to protect these |
| 1150 | * p->signal fields because the whole thread group is dead |
| 1151 | * and nobody can change them. |
| 1152 | * |
| 1153 | * psig->stats_lock also protects us from our sub-threads |
| 1154 | * which can reap other children at the same time. Until |
| 1155 | * we change k_getrusage()-like users to rely on this lock |
| 1156 | * we have to take ->siglock as well. |
| 1157 | * |
| 1158 | * We use thread_group_cputime_adjusted() to get times for |
| 1159 | * the thread group, which consolidates times for all threads |
| 1160 | * in the group including the group leader. |
| 1161 | */ |
| 1162 | thread_group_cputime_adjusted(p, &tgutime, &tgstime); |
| 1163 | spin_lock_irq(¤t->sighand->siglock); |
| 1164 | write_seqlock(&psig->stats_lock); |
| 1165 | psig->cutime += tgutime + sig->cutime; |
| 1166 | psig->cstime += tgstime + sig->cstime; |
| 1167 | psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime; |
| 1168 | psig->cmin_flt += |
| 1169 | p->min_flt + sig->min_flt + sig->cmin_flt; |
| 1170 | psig->cmaj_flt += |
| 1171 | p->maj_flt + sig->maj_flt + sig->cmaj_flt; |
| 1172 | psig->cnvcsw += |
| 1173 | p->nvcsw + sig->nvcsw + sig->cnvcsw; |
| 1174 | psig->cnivcsw += |
| 1175 | p->nivcsw + sig->nivcsw + sig->cnivcsw; |
| 1176 | psig->cinblock += |
| 1177 | task_io_get_inblock(p) + |
| 1178 | sig->inblock + sig->cinblock; |
| 1179 | psig->coublock += |
| 1180 | task_io_get_oublock(p) + |
| 1181 | sig->oublock + sig->coublock; |
| 1182 | maxrss = max(sig->maxrss, sig->cmaxrss); |
| 1183 | if (psig->cmaxrss < maxrss) |
| 1184 | psig->cmaxrss = maxrss; |
| 1185 | task_io_accounting_add(&psig->ioac, &p->ioac); |
| 1186 | task_io_accounting_add(&psig->ioac, &sig->ioac); |
| 1187 | write_sequnlock(&psig->stats_lock); |
| 1188 | spin_unlock_irq(¤t->sighand->siglock); |
| 1189 | } |
| 1190 | |
| 1191 | if (wo->wo_rusage) |
| 1192 | getrusage(p, RUSAGE_BOTH, wo->wo_rusage); |
| 1193 | status = (p->signal->flags & SIGNAL_GROUP_EXIT) |
| 1194 | ? p->signal->group_exit_code : p->exit_code; |
| 1195 | wo->wo_stat = status; |
| 1196 | |
| 1197 | if (state == EXIT_TRACE) { |
| 1198 | write_lock_irq(&tasklist_lock); |
| 1199 | /* We dropped tasklist, ptracer could die and untrace */ |
| 1200 | ptrace_unlink(p); |
| 1201 | |
| 1202 | /* If parent wants a zombie, don't release it now */ |
| 1203 | state = EXIT_ZOMBIE; |
| 1204 | if (do_notify_parent(p, p->exit_signal)) |
| 1205 | state = EXIT_DEAD; |
| 1206 | p->exit_state = state; |
| 1207 | write_unlock_irq(&tasklist_lock); |
| 1208 | } |
| 1209 | if (state == EXIT_DEAD) |
| 1210 | release_task(p); |
| 1211 | |
| 1212 | out_info: |
| 1213 | infop = wo->wo_info; |
| 1214 | if (infop) { |
| 1215 | if ((status & 0x7f) == 0) { |
| 1216 | infop->cause = CLD_EXITED; |
| 1217 | infop->status = status >> 8; |
| 1218 | } else { |
| 1219 | infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; |
| 1220 | infop->status = status & 0x7f; |
| 1221 | } |
| 1222 | infop->pid = pid; |
| 1223 | infop->uid = uid; |
| 1224 | } |
| 1225 | |
| 1226 | return pid; |
| 1227 | } |
| 1228 | |
| 1229 | static int *task_stopped_code(struct task_struct *p, bool ptrace) |
| 1230 | { |
| 1231 | if (ptrace) { |
| 1232 | if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING)) |
| 1233 | return &p->exit_code; |
| 1234 | } else { |
| 1235 | if (p->signal->flags & SIGNAL_STOP_STOPPED) |
| 1236 | return &p->signal->group_exit_code; |
| 1237 | } |
| 1238 | return NULL; |
| 1239 | } |
| 1240 | |
| 1241 | /** |
| 1242 | * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED |
| 1243 | * @wo: wait options |
| 1244 | * @ptrace: is the wait for ptrace |
| 1245 | * @p: task to wait for |
| 1246 | * |
| 1247 | * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED. |
| 1248 | * |
| 1249 | * CONTEXT: |
| 1250 | * read_lock(&tasklist_lock), which is released if return value is |
| 1251 | * non-zero. Also, grabs and releases @p->sighand->siglock. |
| 1252 | * |
| 1253 | * RETURNS: |
| 1254 | * 0 if wait condition didn't exist and search for other wait conditions |
| 1255 | * should continue. Non-zero return, -errno on failure and @p's pid on |
| 1256 | * success, implies that tasklist_lock is released and wait condition |
| 1257 | * search should terminate. |
| 1258 | */ |
| 1259 | static int wait_task_stopped(struct wait_opts *wo, |
| 1260 | int ptrace, struct task_struct *p) |
| 1261 | { |
| 1262 | struct waitid_info *infop; |
| 1263 | int exit_code, *p_code, why; |
| 1264 | uid_t uid = 0; /* unneeded, required by compiler */ |
| 1265 | pid_t pid; |
| 1266 | |
| 1267 | /* |
| 1268 | * Traditionally we see ptrace'd stopped tasks regardless of options. |
| 1269 | */ |
| 1270 | if (!ptrace && !(wo->wo_flags & WUNTRACED)) |
| 1271 | return 0; |
| 1272 | |
| 1273 | if (!task_stopped_code(p, ptrace)) |
| 1274 | return 0; |
| 1275 | |
| 1276 | exit_code = 0; |
| 1277 | spin_lock_irq(&p->sighand->siglock); |
| 1278 | |
| 1279 | p_code = task_stopped_code(p, ptrace); |
| 1280 | if (unlikely(!p_code)) |
| 1281 | goto unlock_sig; |
| 1282 | |
| 1283 | exit_code = *p_code; |
| 1284 | if (!exit_code) |
| 1285 | goto unlock_sig; |
| 1286 | |
| 1287 | if (!unlikely(wo->wo_flags & WNOWAIT)) |
| 1288 | *p_code = 0; |
| 1289 | |
| 1290 | uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
| 1291 | unlock_sig: |
| 1292 | spin_unlock_irq(&p->sighand->siglock); |
| 1293 | if (!exit_code) |
| 1294 | return 0; |
| 1295 | |
| 1296 | /* |
| 1297 | * Now we are pretty sure this task is interesting. |
| 1298 | * Make sure it doesn't get reaped out from under us while we |
| 1299 | * give up the lock and then examine it below. We don't want to |
| 1300 | * keep holding onto the tasklist_lock while we call getrusage and |
| 1301 | * possibly take page faults for user memory. |
| 1302 | */ |
| 1303 | get_task_struct(p); |
| 1304 | pid = task_pid_vnr(p); |
| 1305 | why = ptrace ? CLD_TRAPPED : CLD_STOPPED; |
| 1306 | read_unlock(&tasklist_lock); |
| 1307 | sched_annotate_sleep(); |
| 1308 | if (wo->wo_rusage) |
| 1309 | getrusage(p, RUSAGE_BOTH, wo->wo_rusage); |
| 1310 | put_task_struct(p); |
| 1311 | |
| 1312 | if (likely(!(wo->wo_flags & WNOWAIT))) |
| 1313 | wo->wo_stat = (exit_code << 8) | 0x7f; |
| 1314 | |
| 1315 | infop = wo->wo_info; |
| 1316 | if (infop) { |
| 1317 | infop->cause = why; |
| 1318 | infop->status = exit_code; |
| 1319 | infop->pid = pid; |
| 1320 | infop->uid = uid; |
| 1321 | } |
| 1322 | return pid; |
| 1323 | } |
| 1324 | |
| 1325 | /* |
| 1326 | * Handle do_wait work for one task in a live, non-stopped state. |
| 1327 | * read_lock(&tasklist_lock) on entry. If we return zero, we still hold |
| 1328 | * the lock and this task is uninteresting. If we return nonzero, we have |
| 1329 | * released the lock and the system call should return. |
| 1330 | */ |
| 1331 | static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) |
| 1332 | { |
| 1333 | struct waitid_info *infop; |
| 1334 | pid_t pid; |
| 1335 | uid_t uid; |
| 1336 | |
| 1337 | if (!unlikely(wo->wo_flags & WCONTINUED)) |
| 1338 | return 0; |
| 1339 | |
| 1340 | if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) |
| 1341 | return 0; |
| 1342 | |
| 1343 | spin_lock_irq(&p->sighand->siglock); |
| 1344 | /* Re-check with the lock held. */ |
| 1345 | if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { |
| 1346 | spin_unlock_irq(&p->sighand->siglock); |
| 1347 | return 0; |
| 1348 | } |
| 1349 | if (!unlikely(wo->wo_flags & WNOWAIT)) |
| 1350 | p->signal->flags &= ~SIGNAL_STOP_CONTINUED; |
| 1351 | uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
| 1352 | spin_unlock_irq(&p->sighand->siglock); |
| 1353 | |
| 1354 | pid = task_pid_vnr(p); |
| 1355 | get_task_struct(p); |
| 1356 | read_unlock(&tasklist_lock); |
| 1357 | sched_annotate_sleep(); |
| 1358 | if (wo->wo_rusage) |
| 1359 | getrusage(p, RUSAGE_BOTH, wo->wo_rusage); |
| 1360 | put_task_struct(p); |
| 1361 | |
| 1362 | infop = wo->wo_info; |
| 1363 | if (!infop) { |
| 1364 | wo->wo_stat = 0xffff; |
| 1365 | } else { |
| 1366 | infop->cause = CLD_CONTINUED; |
| 1367 | infop->pid = pid; |
| 1368 | infop->uid = uid; |
| 1369 | infop->status = SIGCONT; |
| 1370 | } |
| 1371 | return pid; |
| 1372 | } |
| 1373 | |
| 1374 | /* |
| 1375 | * Consider @p for a wait by @parent. |
| 1376 | * |
| 1377 | * -ECHILD should be in ->notask_error before the first call. |
| 1378 | * Returns nonzero for a final return, when we have unlocked tasklist_lock. |
| 1379 | * Returns zero if the search for a child should continue; |
| 1380 | * then ->notask_error is 0 if @p is an eligible child, |
| 1381 | * or still -ECHILD. |
| 1382 | */ |
| 1383 | static int wait_consider_task(struct wait_opts *wo, int ptrace, |
| 1384 | struct task_struct *p) |
| 1385 | { |
| 1386 | /* |
| 1387 | * We can race with wait_task_zombie() from another thread. |
| 1388 | * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition |
| 1389 | * can't confuse the checks below. |
| 1390 | */ |
| 1391 | int exit_state = READ_ONCE(p->exit_state); |
| 1392 | int ret; |
| 1393 | |
| 1394 | if (unlikely(exit_state == EXIT_DEAD)) |
| 1395 | return 0; |
| 1396 | |
| 1397 | ret = eligible_child(wo, ptrace, p); |
| 1398 | if (!ret) |
| 1399 | return ret; |
| 1400 | |
| 1401 | if (unlikely(exit_state == EXIT_TRACE)) { |
| 1402 | /* |
| 1403 | * ptrace == 0 means we are the natural parent. In this case |
| 1404 | * we should clear notask_error, debugger will notify us. |
| 1405 | */ |
| 1406 | if (likely(!ptrace)) |
| 1407 | wo->notask_error = 0; |
| 1408 | return 0; |
| 1409 | } |
| 1410 | |
| 1411 | if (likely(!ptrace) && unlikely(p->ptrace)) { |
| 1412 | /* |
| 1413 | * If it is traced by its real parent's group, just pretend |
| 1414 | * the caller is ptrace_do_wait() and reap this child if it |
| 1415 | * is zombie. |
| 1416 | * |
| 1417 | * This also hides group stop state from real parent; otherwise |
| 1418 | * a single stop can be reported twice as group and ptrace stop. |
| 1419 | * If a ptracer wants to distinguish these two events for its |
| 1420 | * own children it should create a separate process which takes |
| 1421 | * the role of real parent. |
| 1422 | */ |
| 1423 | if (!ptrace_reparented(p)) |
| 1424 | ptrace = 1; |
| 1425 | } |
| 1426 | |
| 1427 | /* slay zombie? */ |
| 1428 | if (exit_state == EXIT_ZOMBIE) { |
| 1429 | /* we don't reap group leaders with subthreads */ |
| 1430 | if (!delay_group_leader(p)) { |
| 1431 | /* |
| 1432 | * A zombie ptracee is only visible to its ptracer. |
| 1433 | * Notification and reaping will be cascaded to the |
| 1434 | * real parent when the ptracer detaches. |
| 1435 | */ |
| 1436 | if (unlikely(ptrace) || likely(!p->ptrace)) |
| 1437 | return wait_task_zombie(wo, p); |
| 1438 | } |
| 1439 | |
| 1440 | /* |
| 1441 | * Allow access to stopped/continued state via zombie by |
| 1442 | * falling through. Clearing of notask_error is complex. |
| 1443 | * |
| 1444 | * When !@ptrace: |
| 1445 | * |
| 1446 | * If WEXITED is set, notask_error should naturally be |
| 1447 | * cleared. If not, subset of WSTOPPED|WCONTINUED is set, |
| 1448 | * so, if there are live subthreads, there are events to |
| 1449 | * wait for. If all subthreads are dead, it's still safe |
| 1450 | * to clear - this function will be called again in finite |
| 1451 | * amount time once all the subthreads are released and |
| 1452 | * will then return without clearing. |
| 1453 | * |
| 1454 | * When @ptrace: |
| 1455 | * |
| 1456 | * Stopped state is per-task and thus can't change once the |
| 1457 | * target task dies. Only continued and exited can happen. |
| 1458 | * Clear notask_error if WCONTINUED | WEXITED. |
| 1459 | */ |
| 1460 | if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED))) |
| 1461 | wo->notask_error = 0; |
| 1462 | } else { |
| 1463 | /* |
| 1464 | * @p is alive and it's gonna stop, continue or exit, so |
| 1465 | * there always is something to wait for. |
| 1466 | */ |
| 1467 | wo->notask_error = 0; |
| 1468 | } |
| 1469 | |
| 1470 | /* |
| 1471 | * Wait for stopped. Depending on @ptrace, different stopped state |
| 1472 | * is used and the two don't interact with each other. |
| 1473 | */ |
| 1474 | ret = wait_task_stopped(wo, ptrace, p); |
| 1475 | if (ret) |
| 1476 | return ret; |
| 1477 | |
| 1478 | /* |
| 1479 | * Wait for continued. There's only one continued state and the |
| 1480 | * ptracer can consume it which can confuse the real parent. Don't |
| 1481 | * use WCONTINUED from ptracer. You don't need or want it. |
| 1482 | */ |
| 1483 | return wait_task_continued(wo, p); |
| 1484 | } |
| 1485 | |
| 1486 | /* |
| 1487 | * Do the work of do_wait() for one thread in the group, @tsk. |
| 1488 | * |
| 1489 | * -ECHILD should be in ->notask_error before the first call. |
| 1490 | * Returns nonzero for a final return, when we have unlocked tasklist_lock. |
| 1491 | * Returns zero if the search for a child should continue; then |
| 1492 | * ->notask_error is 0 if there were any eligible children, |
| 1493 | * or still -ECHILD. |
| 1494 | */ |
| 1495 | static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) |
| 1496 | { |
| 1497 | struct task_struct *p; |
| 1498 | |
| 1499 | list_for_each_entry(p, &tsk->children, sibling) { |
| 1500 | int ret = wait_consider_task(wo, 0, p); |
| 1501 | |
| 1502 | if (ret) |
| 1503 | return ret; |
| 1504 | } |
| 1505 | |
| 1506 | return 0; |
| 1507 | } |
| 1508 | |
| 1509 | static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) |
| 1510 | { |
| 1511 | struct task_struct *p; |
| 1512 | |
| 1513 | list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { |
| 1514 | int ret = wait_consider_task(wo, 1, p); |
| 1515 | |
| 1516 | if (ret) |
| 1517 | return ret; |
| 1518 | } |
| 1519 | |
| 1520 | return 0; |
| 1521 | } |
| 1522 | |
| 1523 | static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode, |
| 1524 | int sync, void *key) |
| 1525 | { |
| 1526 | struct wait_opts *wo = container_of(wait, struct wait_opts, |
| 1527 | child_wait); |
| 1528 | struct task_struct *p = key; |
| 1529 | |
| 1530 | if (!eligible_pid(wo, p)) |
| 1531 | return 0; |
| 1532 | |
| 1533 | if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) |
| 1534 | return 0; |
| 1535 | |
| 1536 | return default_wake_function(wait, mode, sync, key); |
| 1537 | } |
| 1538 | |
| 1539 | void __wake_up_parent(struct task_struct *p, struct task_struct *parent) |
| 1540 | { |
| 1541 | __wake_up_sync_key(&parent->signal->wait_chldexit, |
| 1542 | TASK_INTERRUPTIBLE, p); |
| 1543 | } |
| 1544 | |
| 1545 | static bool is_effectively_child(struct wait_opts *wo, bool ptrace, |
| 1546 | struct task_struct *target) |
| 1547 | { |
| 1548 | struct task_struct *parent = |
| 1549 | !ptrace ? target->real_parent : target->parent; |
| 1550 | |
| 1551 | return current == parent || (!(wo->wo_flags & __WNOTHREAD) && |
| 1552 | same_thread_group(current, parent)); |
| 1553 | } |
| 1554 | |
| 1555 | /* |
| 1556 | * Optimization for waiting on PIDTYPE_PID. No need to iterate through child |
| 1557 | * and tracee lists to find the target task. |
| 1558 | */ |
| 1559 | static int do_wait_pid(struct wait_opts *wo) |
| 1560 | { |
| 1561 | bool ptrace; |
| 1562 | struct task_struct *target; |
| 1563 | int retval; |
| 1564 | |
| 1565 | ptrace = false; |
| 1566 | target = pid_task(wo->wo_pid, PIDTYPE_TGID); |
| 1567 | if (target && is_effectively_child(wo, ptrace, target)) { |
| 1568 | retval = wait_consider_task(wo, ptrace, target); |
| 1569 | if (retval) |
| 1570 | return retval; |
| 1571 | } |
| 1572 | |
| 1573 | ptrace = true; |
| 1574 | target = pid_task(wo->wo_pid, PIDTYPE_PID); |
| 1575 | if (target && target->ptrace && |
| 1576 | is_effectively_child(wo, ptrace, target)) { |
| 1577 | retval = wait_consider_task(wo, ptrace, target); |
| 1578 | if (retval) |
| 1579 | return retval; |
| 1580 | } |
| 1581 | |
| 1582 | return 0; |
| 1583 | } |
| 1584 | |
| 1585 | static long do_wait(struct wait_opts *wo) |
| 1586 | { |
| 1587 | int retval; |
| 1588 | |
| 1589 | trace_sched_process_wait(wo->wo_pid); |
| 1590 | |
| 1591 | init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); |
| 1592 | wo->child_wait.private = current; |
| 1593 | add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); |
| 1594 | repeat: |
| 1595 | /* |
| 1596 | * If there is nothing that can match our criteria, just get out. |
| 1597 | * We will clear ->notask_error to zero if we see any child that |
| 1598 | * might later match our criteria, even if we are not able to reap |
| 1599 | * it yet. |
| 1600 | */ |
| 1601 | wo->notask_error = -ECHILD; |
| 1602 | if ((wo->wo_type < PIDTYPE_MAX) && |
| 1603 | (!wo->wo_pid || !pid_has_task(wo->wo_pid, wo->wo_type))) |
| 1604 | goto notask; |
| 1605 | |
| 1606 | set_current_state(TASK_INTERRUPTIBLE); |
| 1607 | read_lock(&tasklist_lock); |
| 1608 | |
| 1609 | if (wo->wo_type == PIDTYPE_PID) { |
| 1610 | retval = do_wait_pid(wo); |
| 1611 | if (retval) |
| 1612 | goto end; |
| 1613 | } else { |
| 1614 | struct task_struct *tsk = current; |
| 1615 | |
| 1616 | do { |
| 1617 | retval = do_wait_thread(wo, tsk); |
| 1618 | if (retval) |
| 1619 | goto end; |
| 1620 | |
| 1621 | retval = ptrace_do_wait(wo, tsk); |
| 1622 | if (retval) |
| 1623 | goto end; |
| 1624 | |
| 1625 | if (wo->wo_flags & __WNOTHREAD) |
| 1626 | break; |
| 1627 | } while_each_thread(current, tsk); |
| 1628 | } |
| 1629 | read_unlock(&tasklist_lock); |
| 1630 | |
| 1631 | notask: |
| 1632 | retval = wo->notask_error; |
| 1633 | if (!retval && !(wo->wo_flags & WNOHANG)) { |
| 1634 | retval = -ERESTARTSYS; |
| 1635 | if (!signal_pending(current)) { |
| 1636 | schedule(); |
| 1637 | goto repeat; |
| 1638 | } |
| 1639 | } |
| 1640 | end: |
| 1641 | __set_current_state(TASK_RUNNING); |
| 1642 | remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); |
| 1643 | return retval; |
| 1644 | } |
| 1645 | |
| 1646 | static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, |
| 1647 | int options, struct rusage *ru) |
| 1648 | { |
| 1649 | struct wait_opts wo; |
| 1650 | struct pid *pid = NULL; |
| 1651 | enum pid_type type; |
| 1652 | long ret; |
| 1653 | unsigned int f_flags = 0; |
| 1654 | |
| 1655 | if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED| |
| 1656 | __WNOTHREAD|__WCLONE|__WALL)) |
| 1657 | return -EINVAL; |
| 1658 | if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) |
| 1659 | return -EINVAL; |
| 1660 | |
| 1661 | switch (which) { |
| 1662 | case P_ALL: |
| 1663 | type = PIDTYPE_MAX; |
| 1664 | break; |
| 1665 | case P_PID: |
| 1666 | type = PIDTYPE_PID; |
| 1667 | if (upid <= 0) |
| 1668 | return -EINVAL; |
| 1669 | |
| 1670 | pid = find_get_pid(upid); |
| 1671 | break; |
| 1672 | case P_PGID: |
| 1673 | type = PIDTYPE_PGID; |
| 1674 | if (upid < 0) |
| 1675 | return -EINVAL; |
| 1676 | |
| 1677 | if (upid) |
| 1678 | pid = find_get_pid(upid); |
| 1679 | else |
| 1680 | pid = get_task_pid(current, PIDTYPE_PGID); |
| 1681 | break; |
| 1682 | case P_PIDFD: |
| 1683 | type = PIDTYPE_PID; |
| 1684 | if (upid < 0) |
| 1685 | return -EINVAL; |
| 1686 | |
| 1687 | pid = pidfd_get_pid(upid, &f_flags); |
| 1688 | if (IS_ERR(pid)) |
| 1689 | return PTR_ERR(pid); |
| 1690 | |
| 1691 | break; |
| 1692 | default: |
| 1693 | return -EINVAL; |
| 1694 | } |
| 1695 | |
| 1696 | wo.wo_type = type; |
| 1697 | wo.wo_pid = pid; |
| 1698 | wo.wo_flags = options; |
| 1699 | wo.wo_info = infop; |
| 1700 | wo.wo_rusage = ru; |
| 1701 | if (f_flags & O_NONBLOCK) |
| 1702 | wo.wo_flags |= WNOHANG; |
| 1703 | |
| 1704 | ret = do_wait(&wo); |
| 1705 | if (!ret && !(options & WNOHANG) && (f_flags & O_NONBLOCK)) |
| 1706 | ret = -EAGAIN; |
| 1707 | |
| 1708 | put_pid(pid); |
| 1709 | return ret; |
| 1710 | } |
| 1711 | |
| 1712 | SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, |
| 1713 | infop, int, options, struct rusage __user *, ru) |
| 1714 | { |
| 1715 | struct rusage r; |
| 1716 | struct waitid_info info = {.status = 0}; |
| 1717 | long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL); |
| 1718 | int signo = 0; |
| 1719 | |
| 1720 | if (err > 0) { |
| 1721 | signo = SIGCHLD; |
| 1722 | err = 0; |
| 1723 | if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) |
| 1724 | return -EFAULT; |
| 1725 | } |
| 1726 | if (!infop) |
| 1727 | return err; |
| 1728 | |
| 1729 | if (!user_write_access_begin(infop, sizeof(*infop))) |
| 1730 | return -EFAULT; |
| 1731 | |
| 1732 | unsafe_put_user(signo, &infop->si_signo, Efault); |
| 1733 | unsafe_put_user(0, &infop->si_errno, Efault); |
| 1734 | unsafe_put_user(info.cause, &infop->si_code, Efault); |
| 1735 | unsafe_put_user(info.pid, &infop->si_pid, Efault); |
| 1736 | unsafe_put_user(info.uid, &infop->si_uid, Efault); |
| 1737 | unsafe_put_user(info.status, &infop->si_status, Efault); |
| 1738 | user_write_access_end(); |
| 1739 | return err; |
| 1740 | Efault: |
| 1741 | user_write_access_end(); |
| 1742 | return -EFAULT; |
| 1743 | } |
| 1744 | |
| 1745 | long kernel_wait4(pid_t upid, int __user *stat_addr, int options, |
| 1746 | struct rusage *ru) |
| 1747 | { |
| 1748 | struct wait_opts wo; |
| 1749 | struct pid *pid = NULL; |
| 1750 | enum pid_type type; |
| 1751 | long ret; |
| 1752 | |
| 1753 | if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| |
| 1754 | __WNOTHREAD|__WCLONE|__WALL)) |
| 1755 | return -EINVAL; |
| 1756 | |
| 1757 | /* -INT_MIN is not defined */ |
| 1758 | if (upid == INT_MIN) |
| 1759 | return -ESRCH; |
| 1760 | |
| 1761 | if (upid == -1) |
| 1762 | type = PIDTYPE_MAX; |
| 1763 | else if (upid < 0) { |
| 1764 | type = PIDTYPE_PGID; |
| 1765 | pid = find_get_pid(-upid); |
| 1766 | } else if (upid == 0) { |
| 1767 | type = PIDTYPE_PGID; |
| 1768 | pid = get_task_pid(current, PIDTYPE_PGID); |
| 1769 | } else /* upid > 0 */ { |
| 1770 | type = PIDTYPE_PID; |
| 1771 | pid = find_get_pid(upid); |
| 1772 | } |
| 1773 | |
| 1774 | wo.wo_type = type; |
| 1775 | wo.wo_pid = pid; |
| 1776 | wo.wo_flags = options | WEXITED; |
| 1777 | wo.wo_info = NULL; |
| 1778 | wo.wo_stat = 0; |
| 1779 | wo.wo_rusage = ru; |
| 1780 | ret = do_wait(&wo); |
| 1781 | put_pid(pid); |
| 1782 | if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr)) |
| 1783 | ret = -EFAULT; |
| 1784 | |
| 1785 | return ret; |
| 1786 | } |
| 1787 | |
| 1788 | int kernel_wait(pid_t pid, int *stat) |
| 1789 | { |
| 1790 | struct wait_opts wo = { |
| 1791 | .wo_type = PIDTYPE_PID, |
| 1792 | .wo_pid = find_get_pid(pid), |
| 1793 | .wo_flags = WEXITED, |
| 1794 | }; |
| 1795 | int ret; |
| 1796 | |
| 1797 | ret = do_wait(&wo); |
| 1798 | if (ret > 0 && wo.wo_stat) |
| 1799 | *stat = wo.wo_stat; |
| 1800 | put_pid(wo.wo_pid); |
| 1801 | return ret; |
| 1802 | } |
| 1803 | |
| 1804 | SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, |
| 1805 | int, options, struct rusage __user *, ru) |
| 1806 | { |
| 1807 | struct rusage r; |
| 1808 | long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL); |
| 1809 | |
| 1810 | if (err > 0) { |
| 1811 | if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) |
| 1812 | return -EFAULT; |
| 1813 | } |
| 1814 | return err; |
| 1815 | } |
| 1816 | |
| 1817 | #ifdef __ARCH_WANT_SYS_WAITPID |
| 1818 | |
| 1819 | /* |
| 1820 | * sys_waitpid() remains for compatibility. waitpid() should be |
| 1821 | * implemented by calling sys_wait4() from libc.a. |
| 1822 | */ |
| 1823 | SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) |
| 1824 | { |
| 1825 | return kernel_wait4(pid, stat_addr, options, NULL); |
| 1826 | } |
| 1827 | |
| 1828 | #endif |
| 1829 | |
| 1830 | #ifdef CONFIG_COMPAT |
| 1831 | COMPAT_SYSCALL_DEFINE4(wait4, |
| 1832 | compat_pid_t, pid, |
| 1833 | compat_uint_t __user *, stat_addr, |
| 1834 | int, options, |
| 1835 | struct compat_rusage __user *, ru) |
| 1836 | { |
| 1837 | struct rusage r; |
| 1838 | long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL); |
| 1839 | if (err > 0) { |
| 1840 | if (ru && put_compat_rusage(&r, ru)) |
| 1841 | return -EFAULT; |
| 1842 | } |
| 1843 | return err; |
| 1844 | } |
| 1845 | |
| 1846 | COMPAT_SYSCALL_DEFINE5(waitid, |
| 1847 | int, which, compat_pid_t, pid, |
| 1848 | struct compat_siginfo __user *, infop, int, options, |
| 1849 | struct compat_rusage __user *, uru) |
| 1850 | { |
| 1851 | struct rusage ru; |
| 1852 | struct waitid_info info = {.status = 0}; |
| 1853 | long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL); |
| 1854 | int signo = 0; |
| 1855 | if (err > 0) { |
| 1856 | signo = SIGCHLD; |
| 1857 | err = 0; |
| 1858 | if (uru) { |
| 1859 | /* kernel_waitid() overwrites everything in ru */ |
| 1860 | if (COMPAT_USE_64BIT_TIME) |
| 1861 | err = copy_to_user(uru, &ru, sizeof(ru)); |
| 1862 | else |
| 1863 | err = put_compat_rusage(&ru, uru); |
| 1864 | if (err) |
| 1865 | return -EFAULT; |
| 1866 | } |
| 1867 | } |
| 1868 | |
| 1869 | if (!infop) |
| 1870 | return err; |
| 1871 | |
| 1872 | if (!user_write_access_begin(infop, sizeof(*infop))) |
| 1873 | return -EFAULT; |
| 1874 | |
| 1875 | unsafe_put_user(signo, &infop->si_signo, Efault); |
| 1876 | unsafe_put_user(0, &infop->si_errno, Efault); |
| 1877 | unsafe_put_user(info.cause, &infop->si_code, Efault); |
| 1878 | unsafe_put_user(info.pid, &infop->si_pid, Efault); |
| 1879 | unsafe_put_user(info.uid, &infop->si_uid, Efault); |
| 1880 | unsafe_put_user(info.status, &infop->si_status, Efault); |
| 1881 | user_write_access_end(); |
| 1882 | return err; |
| 1883 | Efault: |
| 1884 | user_write_access_end(); |
| 1885 | return -EFAULT; |
| 1886 | } |
| 1887 | #endif |
| 1888 | |
| 1889 | /** |
| 1890 | * thread_group_exited - check that a thread group has exited |
| 1891 | * @pid: tgid of thread group to be checked. |
| 1892 | * |
| 1893 | * Test if the thread group represented by tgid has exited (all |
| 1894 | * threads are zombies, dead or completely gone). |
| 1895 | * |
| 1896 | * Return: true if the thread group has exited. false otherwise. |
| 1897 | */ |
| 1898 | bool thread_group_exited(struct pid *pid) |
| 1899 | { |
| 1900 | struct task_struct *task; |
| 1901 | bool exited; |
| 1902 | |
| 1903 | rcu_read_lock(); |
| 1904 | task = pid_task(pid, PIDTYPE_PID); |
| 1905 | exited = !task || |
| 1906 | (READ_ONCE(task->exit_state) && thread_group_empty(task)); |
| 1907 | rcu_read_unlock(); |
| 1908 | |
| 1909 | return exited; |
| 1910 | } |
| 1911 | EXPORT_SYMBOL(thread_group_exited); |
| 1912 | |
| 1913 | /* |
| 1914 | * This needs to be __function_aligned as GCC implicitly makes any |
| 1915 | * implementation of abort() cold and drops alignment specified by |
| 1916 | * -falign-functions=N. |
| 1917 | * |
| 1918 | * See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88345#c11 |
| 1919 | */ |
| 1920 | __weak __function_aligned void abort(void) |
| 1921 | { |
| 1922 | BUG(); |
| 1923 | |
| 1924 | /* if that doesn't kill us, halt */ |
| 1925 | panic("Oops failed to kill thread"); |
| 1926 | } |
| 1927 | EXPORT_SYMBOL(abort); |