diff options
Diffstat (limited to '')
| -rw-r--r-- | kernel/exit.c | 1924 |
1 files changed, 1924 insertions, 0 deletions
diff --git a/kernel/exit.c b/kernel/exit.c new file mode 100644 index 0000000000..21a59a6e1f --- /dev/null +++ b/kernel/exit.c @@ -0,0 +1,1924 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * linux/kernel/exit.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +#include <linux/mm.h> +#include <linux/slab.h> +#include <linux/sched/autogroup.h> +#include <linux/sched/mm.h> +#include <linux/sched/stat.h> +#include <linux/sched/task.h> +#include <linux/sched/task_stack.h> +#include <linux/sched/cputime.h> +#include <linux/interrupt.h> +#include <linux/module.h> +#include <linux/capability.h> +#include <linux/completion.h> +#include <linux/personality.h> +#include <linux/tty.h> +#include <linux/iocontext.h> +#include <linux/key.h> +#include <linux/cpu.h> +#include <linux/acct.h> +#include <linux/tsacct_kern.h> +#include <linux/file.h> +#include <linux/fdtable.h> +#include <linux/freezer.h> +#include <linux/binfmts.h> +#include <linux/nsproxy.h> +#include <linux/pid_namespace.h> +#include <linux/ptrace.h> +#include <linux/profile.h> +#include <linux/mount.h> +#include <linux/proc_fs.h> +#include <linux/kthread.h> +#include <linux/mempolicy.h> +#include <linux/taskstats_kern.h> +#include <linux/delayacct.h> +#include <linux/cgroup.h> +#include <linux/syscalls.h> +#include <linux/signal.h> +#include <linux/posix-timers.h> +#include <linux/cn_proc.h> +#include <linux/mutex.h> +#include <linux/futex.h> +#include <linux/pipe_fs_i.h> +#include <linux/audit.h> /* for audit_free() */ +#include <linux/resource.h> +#include <linux/task_io_accounting_ops.h> +#include <linux/blkdev.h> +#include <linux/task_work.h> +#include <linux/fs_struct.h> +#include <linux/init_task.h> +#include <linux/perf_event.h> +#include <trace/events/sched.h> +#include <linux/hw_breakpoint.h> +#include <linux/oom.h> +#include <linux/writeback.h> +#include <linux/shm.h> +#include <linux/kcov.h> +#include <linux/kmsan.h> +#include <linux/random.h> +#include <linux/rcuwait.h> +#include <linux/compat.h> +#include <linux/io_uring.h> +#include <linux/kprobes.h> +#include <linux/rethook.h> +#include <linux/sysfs.h> +#include <linux/user_events.h> + +#include <linux/uaccess.h> +#include <asm/unistd.h> +#include <asm/mmu_context.h> + +/* + * The default value should be high enough to not crash a system that randomly + * crashes its kernel from time to time, but low enough to at least not permit + * overflowing 32-bit refcounts or the ldsem writer count. + */ +static unsigned int oops_limit = 10000; + +#ifdef CONFIG_SYSCTL +static struct ctl_table kern_exit_table[] = { + { + .procname = "oops_limit", + .data = &oops_limit, + .maxlen = sizeof(oops_limit), + .mode = 0644, + .proc_handler = proc_douintvec, + }, + { } +}; + +static __init int kernel_exit_sysctls_init(void) +{ + register_sysctl_init("kernel", kern_exit_table); + return 0; +} +late_initcall(kernel_exit_sysctls_init); +#endif + +static atomic_t oops_count = ATOMIC_INIT(0); + +#ifdef CONFIG_SYSFS +static ssize_t oops_count_show(struct kobject *kobj, struct kobj_attribute *attr, + char *page) +{ + return sysfs_emit(page, "%d\n", atomic_read(&oops_count)); +} + +static struct kobj_attribute oops_count_attr = __ATTR_RO(oops_count); + +static __init int kernel_exit_sysfs_init(void) +{ + sysfs_add_file_to_group(kernel_kobj, &oops_count_attr.attr, NULL); + return 0; +} +late_initcall(kernel_exit_sysfs_init); +#endif + +static void __unhash_process(struct task_struct *p, bool group_dead) +{ + nr_threads--; + detach_pid(p, PIDTYPE_PID); + if (group_dead) { + detach_pid(p, PIDTYPE_TGID); + detach_pid(p, PIDTYPE_PGID); + detach_pid(p, PIDTYPE_SID); + + list_del_rcu(&p->tasks); + list_del_init(&p->sibling); + __this_cpu_dec(process_counts); + } + list_del_rcu(&p->thread_group); + list_del_rcu(&p->thread_node); +} + +/* + * This function expects the tasklist_lock write-locked. + */ +static void __exit_signal(struct task_struct *tsk) +{ + struct signal_struct *sig = tsk->signal; + bool group_dead = thread_group_leader(tsk); + struct sighand_struct *sighand; + struct tty_struct *tty; + u64 utime, stime; + + sighand = rcu_dereference_check(tsk->sighand, + lockdep_tasklist_lock_is_held()); + spin_lock(&sighand->siglock); + +#ifdef CONFIG_POSIX_TIMERS + posix_cpu_timers_exit(tsk); + if (group_dead) + posix_cpu_timers_exit_group(tsk); +#endif + + if (group_dead) { + tty = sig->tty; + sig->tty = NULL; + } else { + /* + * If there is any task waiting for the group exit + * then notify it: + */ + if (sig->notify_count > 0 && !--sig->notify_count) + wake_up_process(sig->group_exec_task); + + if (tsk == sig->curr_target) + sig->curr_target = next_thread(tsk); + } + + add_device_randomness((const void*) &tsk->se.sum_exec_runtime, + sizeof(unsigned long long)); + + /* + * Accumulate here the counters for all threads as they die. We could + * skip the group leader because it is the last user of signal_struct, + * but we want to avoid the race with thread_group_cputime() which can + * see the empty ->thread_head list. + */ + task_cputime(tsk, &utime, &stime); + write_seqlock(&sig->stats_lock); + sig->utime += utime; + sig->stime += stime; + sig->gtime += task_gtime(tsk); + sig->min_flt += tsk->min_flt; + sig->maj_flt += tsk->maj_flt; + sig->nvcsw += tsk->nvcsw; + sig->nivcsw += tsk->nivcsw; + sig->inblock += task_io_get_inblock(tsk); + sig->oublock += task_io_get_oublock(tsk); + task_io_accounting_add(&sig->ioac, &tsk->ioac); + sig->sum_sched_runtime += tsk->se.sum_exec_runtime; + sig->nr_threads--; + __unhash_process(tsk, group_dead); + write_sequnlock(&sig->stats_lock); + + /* + * Do this under ->siglock, we can race with another thread + * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. + */ + flush_sigqueue(&tsk->pending); + tsk->sighand = NULL; + spin_unlock(&sighand->siglock); + + __cleanup_sighand(sighand); + clear_tsk_thread_flag(tsk, TIF_SIGPENDING); + if (group_dead) { + flush_sigqueue(&sig->shared_pending); + tty_kref_put(tty); + } +} + +static void delayed_put_task_struct(struct rcu_head *rhp) +{ + struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); + + kprobe_flush_task(tsk); + rethook_flush_task(tsk); + perf_event_delayed_put(tsk); + trace_sched_process_free(tsk); + put_task_struct(tsk); +} + +void put_task_struct_rcu_user(struct task_struct *task) +{ + if (refcount_dec_and_test(&task->rcu_users)) + call_rcu(&task->rcu, delayed_put_task_struct); +} + +void __weak release_thread(struct task_struct *dead_task) +{ +} + +void release_task(struct task_struct *p) +{ + struct task_struct *leader; + struct pid *thread_pid; + int zap_leader; +repeat: + /* don't need to get the RCU readlock here - the process is dead and + * can't be modifying its own credentials. But shut RCU-lockdep up */ + rcu_read_lock(); + dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); + rcu_read_unlock(); + + cgroup_release(p); + + write_lock_irq(&tasklist_lock); + ptrace_release_task(p); + thread_pid = get_pid(p->thread_pid); + __exit_signal(p); + + /* + * If we are the last non-leader member of the thread + * group, and the leader is zombie, then notify the + * group leader's parent process. (if it wants notification.) + */ + zap_leader = 0; + leader = p->group_leader; + if (leader != p && thread_group_empty(leader) + && leader->exit_state == EXIT_ZOMBIE) { + /* + * If we were the last child thread and the leader has + * exited already, and the leader's parent ignores SIGCHLD, + * then we are the one who should release the leader. + */ + zap_leader = do_notify_parent(leader, leader->exit_signal); + if (zap_leader) + leader->exit_state = EXIT_DEAD; + } + + write_unlock_irq(&tasklist_lock); + seccomp_filter_release(p); + proc_flush_pid(thread_pid); + put_pid(thread_pid); + release_thread(p); + put_task_struct_rcu_user(p); + + p = leader; + if (unlikely(zap_leader)) + goto repeat; +} + +int rcuwait_wake_up(struct rcuwait *w) +{ + int ret = 0; + struct task_struct *task; + + rcu_read_lock(); + + /* + * Order condition vs @task, such that everything prior to the load + * of @task is visible. This is the condition as to why the user called + * rcuwait_wake() in the first place. Pairs with set_current_state() + * barrier (A) in rcuwait_wait_event(). + * + * WAIT WAKE + * [S] tsk = current [S] cond = true + * MB (A) MB (B) + * [L] cond [L] tsk + */ + smp_mb(); /* (B) */ + + task = rcu_dereference(w->task); + if (task) + ret = wake_up_process(task); + rcu_read_unlock(); + + return ret; +} +EXPORT_SYMBOL_GPL(rcuwait_wake_up); + +/* + * Determine if a process group is "orphaned", according to the POSIX + * definition in 2.2.2.52. Orphaned process groups are not to be affected + * by terminal-generated stop signals. Newly orphaned process groups are + * to receive a SIGHUP and a SIGCONT. + * + * "I ask you, have you ever known what it is to be an orphan?" + */ +static int will_become_orphaned_pgrp(struct pid *pgrp, + struct task_struct *ignored_task) +{ + struct task_struct *p; + + do_each_pid_task(pgrp, PIDTYPE_PGID, p) { + if ((p == ignored_task) || + (p->exit_state && thread_group_empty(p)) || + is_global_init(p->real_parent)) + continue; + + if (task_pgrp(p->real_parent) != pgrp && + task_session(p->real_parent) == task_session(p)) + return 0; + } while_each_pid_task(pgrp, PIDTYPE_PGID, p); + + return 1; +} + +int is_current_pgrp_orphaned(void) +{ + int retval; + + read_lock(&tasklist_lock); + retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); + read_unlock(&tasklist_lock); + + return retval; +} + +static bool has_stopped_jobs(struct pid *pgrp) +{ + struct task_struct *p; + + do_each_pid_task(pgrp, PIDTYPE_PGID, p) { + if (p->signal->flags & SIGNAL_STOP_STOPPED) + return true; + } while_each_pid_task(pgrp, PIDTYPE_PGID, p); + + return false; +} + +/* + * Check to see if any process groups have become orphaned as + * a result of our exiting, and if they have any stopped jobs, + * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) + */ +static void +kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) +{ + struct pid *pgrp = task_pgrp(tsk); + struct task_struct *ignored_task = tsk; + + if (!parent) + /* exit: our father is in a different pgrp than + * we are and we were the only connection outside. + */ + parent = tsk->real_parent; + else + /* reparent: our child is in a different pgrp than + * we are, and it was the only connection outside. + */ + ignored_task = NULL; + + if (task_pgrp(parent) != pgrp && + task_session(parent) == task_session(tsk) && + will_become_orphaned_pgrp(pgrp, ignored_task) && + has_stopped_jobs(pgrp)) { + __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); + __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); + } +} + +static void coredump_task_exit(struct task_struct *tsk) +{ + struct core_state *core_state; + + /* + * Serialize with any possible pending coredump. + * We must hold siglock around checking core_state + * and setting PF_POSTCOREDUMP. The core-inducing thread + * will increment ->nr_threads for each thread in the + * group without PF_POSTCOREDUMP set. + */ + spin_lock_irq(&tsk->sighand->siglock); + tsk->flags |= PF_POSTCOREDUMP; + core_state = tsk->signal->core_state; + spin_unlock_irq(&tsk->sighand->siglock); + + /* The vhost_worker does not particpate in coredumps */ + if (core_state && + ((tsk->flags & (PF_IO_WORKER | PF_USER_WORKER)) != PF_USER_WORKER)) { + struct core_thread self; + + self.task = current; + if (self.task->flags & PF_SIGNALED) + self.next = xchg(&core_state->dumper.next, &self); + else + self.task = NULL; + /* + * Implies mb(), the result of xchg() must be visible + * to core_state->dumper. + */ + if (atomic_dec_and_test(&core_state->nr_threads)) + complete(&core_state->startup); + + for (;;) { + set_current_state(TASK_UNINTERRUPTIBLE|TASK_FREEZABLE); + if (!self.task) /* see coredump_finish() */ + break; + schedule(); + } + __set_current_state(TASK_RUNNING); + } +} + +#ifdef CONFIG_MEMCG +/* + * A task is exiting. If it owned this mm, find a new owner for the mm. + */ +void mm_update_next_owner(struct mm_struct *mm) +{ + struct task_struct *c, *g, *p = current; + +retry: + /* + * If the exiting or execing task is not the owner, it's + * someone else's problem. + */ + if (mm->owner != p) + return; + /* + * The current owner is exiting/execing and there are no other + * candidates. Do not leave the mm pointing to a possibly + * freed task structure. + */ + if (atomic_read(&mm->mm_users) <= 1) { + WRITE_ONCE(mm->owner, NULL); + return; + } + + read_lock(&tasklist_lock); + /* + * Search in the children + */ + list_for_each_entry(c, &p->children, sibling) { + if (c->mm == mm) + goto assign_new_owner; + } + + /* + * Search in the siblings + */ + list_for_each_entry(c, &p->real_parent->children, sibling) { + if (c->mm == mm) + goto assign_new_owner; + } + + /* + * Search through everything else, we should not get here often. + */ + for_each_process(g) { + if (g->flags & PF_KTHREAD) + continue; + for_each_thread(g, c) { + if (c->mm == mm) + goto assign_new_owner; + if (c->mm) + break; + } + } + read_unlock(&tasklist_lock); + /* + * We found no owner yet mm_users > 1: this implies that we are + * most likely racing with swapoff (try_to_unuse()) or /proc or + * ptrace or page migration (get_task_mm()). Mark owner as NULL. + */ + WRITE_ONCE(mm->owner, NULL); + return; + +assign_new_owner: + BUG_ON(c == p); + get_task_struct(c); + /* + * The task_lock protects c->mm from changing. + * We always want mm->owner->mm == mm + */ + task_lock(c); + /* + * Delay read_unlock() till we have the task_lock() + * to ensure that c does not slip away underneath us + */ + read_unlock(&tasklist_lock); + if (c->mm != mm) { + task_unlock(c); + put_task_struct(c); + goto retry; + } + WRITE_ONCE(mm->owner, c); + lru_gen_migrate_mm(mm); + task_unlock(c); + put_task_struct(c); +} +#endif /* CONFIG_MEMCG */ + +/* + * Turn us into a lazy TLB process if we + * aren't already.. + */ +static void exit_mm(void) +{ + struct mm_struct *mm = current->mm; + + exit_mm_release(current, mm); + if (!mm) + return; + sync_mm_rss(mm); + mmap_read_lock(mm); + mmgrab_lazy_tlb(mm); + BUG_ON(mm != current->active_mm); + /* more a memory barrier than a real lock */ + task_lock(current); + /* + * When a thread stops operating on an address space, the loop + * in membarrier_private_expedited() may not observe that + * tsk->mm, and the loop in membarrier_global_expedited() may + * not observe a MEMBARRIER_STATE_GLOBAL_EXPEDITED + * rq->membarrier_state, so those would not issue an IPI. + * Membarrier requires a memory barrier after accessing + * user-space memory, before clearing tsk->mm or the + * rq->membarrier_state. + */ + smp_mb__after_spinlock(); + local_irq_disable(); + current->mm = NULL; + membarrier_update_current_mm(NULL); + enter_lazy_tlb(mm, current); + local_irq_enable(); + task_unlock(current); + mmap_read_unlock(mm); + mm_update_next_owner(mm); + mmput(mm); + if (test_thread_flag(TIF_MEMDIE)) + exit_oom_victim(); +} + +static struct task_struct *find_alive_thread(struct task_struct *p) +{ + struct task_struct *t; + + for_each_thread(p, t) { + if (!(t->flags & PF_EXITING)) + return t; + } + return NULL; +} + +static struct task_struct *find_child_reaper(struct task_struct *father, + struct list_head *dead) + __releases(&tasklist_lock) + __acquires(&tasklist_lock) +{ + struct pid_namespace *pid_ns = task_active_pid_ns(father); + struct task_struct *reaper = pid_ns->child_reaper; + struct task_struct *p, *n; + + if (likely(reaper != father)) + return reaper; + + reaper = find_alive_thread(father); + if (reaper) { + pid_ns->child_reaper = reaper; + return reaper; + } + + write_unlock_irq(&tasklist_lock); + + list_for_each_entry_safe(p, n, dead, ptrace_entry) { + list_del_init(&p->ptrace_entry); + release_task(p); + } + + zap_pid_ns_processes(pid_ns); + write_lock_irq(&tasklist_lock); + + return father; +} + +/* + * When we die, we re-parent all our children, and try to: + * 1. give them to another thread in our thread group, if such a member exists + * 2. give it to the first ancestor process which prctl'd itself as a + * child_subreaper for its children (like a service manager) + * 3. give it to the init process (PID 1) in our pid namespace + */ +static struct task_struct *find_new_reaper(struct task_struct *father, + struct task_struct *child_reaper) +{ + struct task_struct *thread, *reaper; + + thread = find_alive_thread(father); + if (thread) + return thread; + + if (father->signal->has_child_subreaper) { + unsigned int ns_level = task_pid(father)->level; + /* + * Find the first ->is_child_subreaper ancestor in our pid_ns. + * We can't check reaper != child_reaper to ensure we do not + * cross the namespaces, the exiting parent could be injected + * by setns() + fork(). + * We check pid->level, this is slightly more efficient than + * task_active_pid_ns(reaper) != task_active_pid_ns(father). + */ + for (reaper = father->real_parent; + task_pid(reaper)->level == ns_level; + reaper = reaper->real_parent) { + if (reaper == &init_task) + break; + if (!reaper->signal->is_child_subreaper) + continue; + thread = find_alive_thread(reaper); + if (thread) + return thread; + } + } + + return child_reaper; +} + +/* +* Any that need to be release_task'd are put on the @dead list. + */ +static void reparent_leader(struct task_struct *father, struct task_struct *p, + struct list_head *dead) +{ + if (unlikely(p->exit_state == EXIT_DEAD)) + return; + + /* We don't want people slaying init. */ + p->exit_signal = SIGCHLD; + + /* If it has exited notify the new parent about this child's death. */ + if (!p->ptrace && + p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { + if (do_notify_parent(p, p->exit_signal)) { + p->exit_state = EXIT_DEAD; + list_add(&p->ptrace_entry, dead); + } + } + + kill_orphaned_pgrp(p, father); +} + +/* + * This does two things: + * + * A. Make init inherit all the child processes + * B. Check to see if any process groups have become orphaned + * as a result of our exiting, and if they have any stopped + * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) + */ +static void forget_original_parent(struct task_struct *father, + struct list_head *dead) +{ + struct task_struct *p, *t, *reaper; + + if (unlikely(!list_empty(&father->ptraced))) + exit_ptrace(father, dead); + + /* Can drop and reacquire tasklist_lock */ + reaper = find_child_reaper(father, dead); + if (list_empty(&father->children)) + return; + + reaper = find_new_reaper(father, reaper); + list_for_each_entry(p, &father->children, sibling) { + for_each_thread(p, t) { + RCU_INIT_POINTER(t->real_parent, reaper); + BUG_ON((!t->ptrace) != (rcu_access_pointer(t->parent) == father)); + if (likely(!t->ptrace)) + t->parent = t->real_parent; + if (t->pdeath_signal) + group_send_sig_info(t->pdeath_signal, + SEND_SIG_NOINFO, t, + PIDTYPE_TGID); + } + /* + * If this is a threaded reparent there is no need to + * notify anyone anything has happened. + */ + if (!same_thread_group(reaper, father)) + reparent_leader(father, p, dead); + } + list_splice_tail_init(&father->children, &reaper->children); +} + +/* + * Send signals to all our closest relatives so that they know + * to properly mourn us.. + */ +static void exit_notify(struct task_struct *tsk, int group_dead) +{ + bool autoreap; + struct task_struct *p, *n; + LIST_HEAD(dead); + + write_lock_irq(&tasklist_lock); + forget_original_parent(tsk, &dead); + + if (group_dead) + kill_orphaned_pgrp(tsk->group_leader, NULL); + + tsk->exit_state = EXIT_ZOMBIE; + if (unlikely(tsk->ptrace)) { + int sig = thread_group_leader(tsk) && + thread_group_empty(tsk) && + !ptrace_reparented(tsk) ? + tsk->exit_signal : SIGCHLD; + autoreap = do_notify_parent(tsk, sig); + } else if (thread_group_leader(tsk)) { + autoreap = thread_group_empty(tsk) && + do_notify_parent(tsk, tsk->exit_signal); + } else { + autoreap = true; + } + + if (autoreap) { + tsk->exit_state = EXIT_DEAD; + list_add(&tsk->ptrace_entry, &dead); + } + + /* mt-exec, de_thread() is waiting for group leader */ + if (unlikely(tsk->signal->notify_count < 0)) + wake_up_process(tsk->signal->group_exec_task); + write_unlock_irq(&tasklist_lock); + + list_for_each_entry_safe(p, n, &dead, ptrace_entry) { + list_del_init(&p->ptrace_entry); + release_task(p); + } +} + +#ifdef CONFIG_DEBUG_STACK_USAGE +static void check_stack_usage(void) +{ + static DEFINE_SPINLOCK(low_water_lock); + static int lowest_to_date = THREAD_SIZE; + unsigned long free; + + free = stack_not_used(current); + + if (free >= lowest_to_date) + return; + + spin_lock(&low_water_lock); + if (free < lowest_to_date) { + pr_info("%s (%d) used greatest stack depth: %lu bytes left\n", + current->comm, task_pid_nr(current), free); + lowest_to_date = free; + } + spin_unlock(&low_water_lock); +} +#else +static inline void check_stack_usage(void) {} +#endif + +static void synchronize_group_exit(struct task_struct *tsk, long code) +{ + struct sighand_struct *sighand = tsk->sighand; + struct signal_struct *signal = tsk->signal; + + spin_lock_irq(&sighand->siglock); + signal->quick_threads--; + if ((signal->quick_threads == 0) && + !(signal->flags & SIGNAL_GROUP_EXIT)) { + signal->flags = SIGNAL_GROUP_EXIT; + signal->group_exit_code = code; + signal->group_stop_count = 0; + } + spin_unlock_irq(&sighand->siglock); +} + +void __noreturn do_exit(long code) +{ + struct task_struct *tsk = current; + int group_dead; + + WARN_ON(irqs_disabled()); + + synchronize_group_exit(tsk, code); + + WARN_ON(tsk->plug); + + kcov_task_exit(tsk); + kmsan_task_exit(tsk); + + coredump_task_exit(tsk); + ptrace_event(PTRACE_EVENT_EXIT, code); + user_events_exit(tsk); + + io_uring_files_cancel(); + exit_signals(tsk); /* sets PF_EXITING */ + + /* sync mm's RSS info before statistics gathering */ + if (tsk->mm) + sync_mm_rss(tsk->mm); + acct_update_integrals(tsk); + group_dead = atomic_dec_and_test(&tsk->signal->live); + if (group_dead) { + /* + * If the last thread of global init has exited, panic + * immediately to get a useable coredump. + */ + if (unlikely(is_global_init(tsk))) + panic("Attempted to kill init! exitcode=0x%08x\n", + tsk->signal->group_exit_code ?: (int)code); + +#ifdef CONFIG_POSIX_TIMERS + hrtimer_cancel(&tsk->signal->real_timer); + exit_itimers(tsk); +#endif + if (tsk->mm) + setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); + } + acct_collect(code, group_dead); + if (group_dead) + tty_audit_exit(); + audit_free(tsk); + + tsk->exit_code = code; + taskstats_exit(tsk, group_dead); + + exit_mm(); + + if (group_dead) + acct_process(); + trace_sched_process_exit(tsk); + + exit_sem(tsk); + exit_shm(tsk); + exit_files(tsk); + exit_fs(tsk); + if (group_dead) + disassociate_ctty(1); + exit_task_namespaces(tsk); + exit_task_work(tsk); + exit_thread(tsk); + + /* + * Flush inherited counters to the parent - before the parent + * gets woken up by child-exit notifications. + * + * because of cgroup mode, must be called before cgroup_exit() + */ + perf_event_exit_task(tsk); + + sched_autogroup_exit_task(tsk); + cgroup_exit(tsk); + + /* + * FIXME: do that only when needed, using sched_exit tracepoint + */ + flush_ptrace_hw_breakpoint(tsk); + + exit_tasks_rcu_start(); + exit_notify(tsk, group_dead); + proc_exit_connector(tsk); + mpol_put_task_policy(tsk); +#ifdef CONFIG_FUTEX + if (unlikely(current->pi_state_cache)) + kfree(current->pi_state_cache); +#endif + /* + * Make sure we are holding no locks: + */ + debug_check_no_locks_held(); + + if (tsk->io_context) + exit_io_context(tsk); + + if (tsk->splice_pipe) + free_pipe_info(tsk->splice_pipe); + + if (tsk->task_frag.page) + put_page(tsk->task_frag.page); + + exit_task_stack_account(tsk); + + check_stack_usage(); + preempt_disable(); + if (tsk->nr_dirtied) + __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); + exit_rcu(); + exit_tasks_rcu_finish(); + + lockdep_free_task(tsk); + do_task_dead(); +} + +void __noreturn make_task_dead(int signr) +{ + /* + * Take the task off the cpu after something catastrophic has + * happened. + * + * We can get here from a kernel oops, sometimes with preemption off. + * Start by checking for critical errors. + * Then fix up important state like USER_DS and preemption. + * Then do everything else. + */ + struct task_struct *tsk = current; + unsigned int limit; + + if (unlikely(in_interrupt())) + panic("Aiee, killing interrupt handler!"); + if (unlikely(!tsk->pid)) + panic("Attempted to kill the idle task!"); + + if (unlikely(irqs_disabled())) { + pr_info("note: %s[%d] exited with irqs disabled\n", + current->comm, task_pid_nr(current)); + local_irq_enable(); + } + if (unlikely(in_atomic())) { + pr_info("note: %s[%d] exited with preempt_count %d\n", + current->comm, task_pid_nr(current), + preempt_count()); + preempt_count_set(PREEMPT_ENABLED); + } + + /* + * Every time the system oopses, if the oops happens while a reference + * to an object was held, the reference leaks. + * If the oops doesn't also leak memory, repeated oopsing can cause + * reference counters to wrap around (if they're not using refcount_t). + * This means that repeated oopsing can make unexploitable-looking bugs + * exploitable through repeated oopsing. + * To make sure this can't happen, place an upper bound on how often the + * kernel may oops without panic(). + */ + limit = READ_ONCE(oops_limit); + if (atomic_inc_return(&oops_count) >= limit && limit) + panic("Oopsed too often (kernel.oops_limit is %d)", limit); + + /* + * We're taking recursive faults here in make_task_dead. Safest is to just + * leave this task alone and wait for reboot. + */ + if (unlikely(tsk->flags & PF_EXITING)) { + pr_alert("Fixing recursive fault but reboot is needed!\n"); + futex_exit_recursive(tsk); + tsk->exit_state = EXIT_DEAD; + refcount_inc(&tsk->rcu_users); + do_task_dead(); + } + + do_exit(signr); +} + +SYSCALL_DEFINE1(exit, int, error_code) +{ + do_exit((error_code&0xff)<<8); +} + +/* + * Take down every thread in the group. This is called by fatal signals + * as well as by sys_exit_group (below). + */ +void __noreturn +do_group_exit(int exit_code) +{ + struct signal_struct *sig = current->signal; + + if (sig->flags & SIGNAL_GROUP_EXIT) + exit_code = sig->group_exit_code; + else if (sig->group_exec_task) + exit_code = 0; + else { + struct sighand_struct *const sighand = current->sighand; + + spin_lock_irq(&sighand->siglock); + if (sig->flags & SIGNAL_GROUP_EXIT) + /* Another thread got here before we took the lock. */ + exit_code = sig->group_exit_code; + else if (sig->group_exec_task) + exit_code = 0; + else { + sig->group_exit_code = exit_code; + sig->flags = SIGNAL_GROUP_EXIT; + zap_other_threads(current); + } + spin_unlock_irq(&sighand->siglock); + } + + do_exit(exit_code); + /* NOTREACHED */ +} + +/* + * this kills every thread in the thread group. Note that any externally + * wait4()-ing process will get the correct exit code - even if this + * thread is not the thread group leader. + */ +SYSCALL_DEFINE1(exit_group, int, error_code) +{ + do_group_exit((error_code & 0xff) << 8); + /* NOTREACHED */ + return 0; +} + +struct waitid_info { + pid_t pid; + uid_t uid; + int status; + int cause; +}; + +struct wait_opts { + enum pid_type wo_type; + int wo_flags; + struct pid *wo_pid; + + struct waitid_info *wo_info; + int wo_stat; + struct rusage *wo_rusage; + + wait_queue_entry_t child_wait; + int notask_error; +}; + +static int eligible_pid(struct wait_opts *wo, struct task_struct *p) +{ + return wo->wo_type == PIDTYPE_MAX || + task_pid_type(p, wo->wo_type) == wo->wo_pid; +} + +static int +eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p) +{ + if (!eligible_pid(wo, p)) + return 0; + + /* + * Wait for all children (clone and not) if __WALL is set or + * if it is traced by us. + */ + if (ptrace || (wo->wo_flags & __WALL)) + return 1; + + /* + * Otherwise, wait for clone children *only* if __WCLONE is set; + * otherwise, wait for non-clone children *only*. + * + * Note: a "clone" child here is one that reports to its parent + * using a signal other than SIGCHLD, or a non-leader thread which + * we can only see if it is traced by us. + */ + if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) + return 0; + + return 1; +} + +/* + * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold + * read_lock(&tasklist_lock) on entry. If we return zero, we still hold + * the lock and this task is uninteresting. If we return nonzero, we have + * released the lock and the system call should return. + */ +static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) +{ + int state, status; + pid_t pid = task_pid_vnr(p); + uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); + struct waitid_info *infop; + + if (!likely(wo->wo_flags & WEXITED)) + return 0; + + if (unlikely(wo->wo_flags & WNOWAIT)) { + status = (p->signal->flags & SIGNAL_GROUP_EXIT) + ? p->signal->group_exit_code : p->exit_code; + get_task_struct(p); + read_unlock(&tasklist_lock); + sched_annotate_sleep(); + if (wo->wo_rusage) + getrusage(p, RUSAGE_BOTH, wo->wo_rusage); + put_task_struct(p); + goto out_info; + } + /* + * Move the task's state to DEAD/TRACE, only one thread can do this. + */ + state = (ptrace_reparented(p) && thread_group_leader(p)) ? + EXIT_TRACE : EXIT_DEAD; + if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) + return 0; + /* + * We own this thread, nobody else can reap it. + */ + read_unlock(&tasklist_lock); + sched_annotate_sleep(); + + /* + * Check thread_group_leader() to exclude the traced sub-threads. + */ + if (state == EXIT_DEAD && thread_group_leader(p)) { + struct signal_struct *sig = p->signal; + struct signal_struct *psig = current->signal; + unsigned long maxrss; + u64 tgutime, tgstime; + + /* + * The resource counters for the group leader are in its + * own task_struct. Those for dead threads in the group + * are in its signal_struct, as are those for the child + * processes it has previously reaped. All these + * accumulate in the parent's signal_struct c* fields. + * + * We don't bother to take a lock here to protect these + * p->signal fields because the whole thread group is dead + * and nobody can change them. + * + * psig->stats_lock also protects us from our sub-threads + * which can reap other children at the same time. Until + * we change k_getrusage()-like users to rely on this lock + * we have to take ->siglock as well. + * + * We use thread_group_cputime_adjusted() to get times for + * the thread group, which consolidates times for all threads + * in the group including the group leader. + */ + thread_group_cputime_adjusted(p, &tgutime, &tgstime); + spin_lock_irq(¤t->sighand->siglock); + write_seqlock(&psig->stats_lock); + psig->cutime += tgutime + sig->cutime; + psig->cstime += tgstime + sig->cstime; + psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime; + psig->cmin_flt += + p->min_flt + sig->min_flt + sig->cmin_flt; + psig->cmaj_flt += + p->maj_flt + sig->maj_flt + sig->cmaj_flt; + psig->cnvcsw += + p->nvcsw + sig->nvcsw + sig->cnvcsw; + psig->cnivcsw += + p->nivcsw + sig->nivcsw + sig->cnivcsw; + psig->cinblock += + task_io_get_inblock(p) + + sig->inblock + sig->cinblock; + psig->coublock += + task_io_get_oublock(p) + + sig->oublock + sig->coublock; + maxrss = max(sig->maxrss, sig->cmaxrss); + if (psig->cmaxrss < maxrss) + psig->cmaxrss = maxrss; + task_io_accounting_add(&psig->ioac, &p->ioac); + task_io_accounting_add(&psig->ioac, &sig->ioac); + write_sequnlock(&psig->stats_lock); + spin_unlock_irq(¤t->sighand->siglock); + } + + if (wo->wo_rusage) + getrusage(p, RUSAGE_BOTH, wo->wo_rusage); + status = (p->signal->flags & SIGNAL_GROUP_EXIT) + ? p->signal->group_exit_code : p->exit_code; + wo->wo_stat = status; + + if (state == EXIT_TRACE) { + write_lock_irq(&tasklist_lock); + /* We dropped tasklist, ptracer could die and untrace */ + ptrace_unlink(p); + + /* If parent wants a zombie, don't release it now */ + state = EXIT_ZOMBIE; + if (do_notify_parent(p, p->exit_signal)) + state = EXIT_DEAD; + p->exit_state = state; + write_unlock_irq(&tasklist_lock); + } + if (state == EXIT_DEAD) + release_task(p); + +out_info: + infop = wo->wo_info; + if (infop) { + if ((status & 0x7f) == 0) { + infop->cause = CLD_EXITED; + infop->status = status >> 8; + } else { + infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; + infop->status = status & 0x7f; + } + infop->pid = pid; + infop->uid = uid; + } + + return pid; +} + +static int *task_stopped_code(struct task_struct *p, bool ptrace) +{ + if (ptrace) { + if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING)) + return &p->exit_code; + } else { + if (p->signal->flags & SIGNAL_STOP_STOPPED) + return &p->signal->group_exit_code; + } + return NULL; +} + +/** + * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED + * @wo: wait options + * @ptrace: is the wait for ptrace + * @p: task to wait for + * + * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED. + * + * CONTEXT: + * read_lock(&tasklist_lock), which is released if return value is + * non-zero. Also, grabs and releases @p->sighand->siglock. + * + * RETURNS: + * 0 if wait condition didn't exist and search for other wait conditions + * should continue. Non-zero return, -errno on failure and @p's pid on + * success, implies that tasklist_lock is released and wait condition + * search should terminate. + */ +static int wait_task_stopped(struct wait_opts *wo, + int ptrace, struct task_struct *p) +{ + struct waitid_info *infop; + int exit_code, *p_code, why; + uid_t uid = 0; /* unneeded, required by compiler */ + pid_t pid; + + /* + * Traditionally we see ptrace'd stopped tasks regardless of options. + */ + if (!ptrace && !(wo->wo_flags & WUNTRACED)) + return 0; + + if (!task_stopped_code(p, ptrace)) + return 0; + + exit_code = 0; + spin_lock_irq(&p->sighand->siglock); + + p_code = task_stopped_code(p, ptrace); + if (unlikely(!p_code)) + goto unlock_sig; + + exit_code = *p_code; + if (!exit_code) + goto unlock_sig; + + if (!unlikely(wo->wo_flags & WNOWAIT)) + *p_code = 0; + + uid = from_kuid_munged(current_user_ns(), task_uid(p)); +unlock_sig: + spin_unlock_irq(&p->sighand->siglock); + if (!exit_code) + return 0; + + /* + * Now we are pretty sure this task is interesting. + * Make sure it doesn't get reaped out from under us while we + * give up the lock and then examine it below. We don't want to + * keep holding onto the tasklist_lock while we call getrusage and + * possibly take page faults for user memory. + */ + get_task_struct(p); + pid = task_pid_vnr(p); + why = ptrace ? CLD_TRAPPED : CLD_STOPPED; + read_unlock(&tasklist_lock); + sched_annotate_sleep(); + if (wo->wo_rusage) + getrusage(p, RUSAGE_BOTH, wo->wo_rusage); + put_task_struct(p); + + if (likely(!(wo->wo_flags & WNOWAIT))) + wo->wo_stat = (exit_code << 8) | 0x7f; + + infop = wo->wo_info; + if (infop) { + infop->cause = why; + infop->status = exit_code; + infop->pid = pid; + infop->uid = uid; + } + return pid; +} + +/* + * Handle do_wait work for one task in a live, non-stopped state. + * read_lock(&tasklist_lock) on entry. If we return zero, we still hold + * the lock and this task is uninteresting. If we return nonzero, we have + * released the lock and the system call should return. + */ +static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) +{ + struct waitid_info *infop; + pid_t pid; + uid_t uid; + + if (!unlikely(wo->wo_flags & WCONTINUED)) + return 0; + + if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) + return 0; + + spin_lock_irq(&p->sighand->siglock); + /* Re-check with the lock held. */ + if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { + spin_unlock_irq(&p->sighand->siglock); + return 0; + } + if (!unlikely(wo->wo_flags & WNOWAIT)) + p->signal->flags &= ~SIGNAL_STOP_CONTINUED; + uid = from_kuid_munged(current_user_ns(), task_uid(p)); + spin_unlock_irq(&p->sighand->siglock); + + pid = task_pid_vnr(p); + get_task_struct(p); + read_unlock(&tasklist_lock); + sched_annotate_sleep(); + if (wo->wo_rusage) + getrusage(p, RUSAGE_BOTH, wo->wo_rusage); + put_task_struct(p); + + infop = wo->wo_info; + if (!infop) { + wo->wo_stat = 0xffff; + } else { + infop->cause = CLD_CONTINUED; + infop->pid = pid; + infop->uid = uid; + infop->status = SIGCONT; + } + return pid; +} + +/* + * Consider @p for a wait by @parent. + * + * -ECHILD should be in ->notask_error before the first call. + * Returns nonzero for a final return, when we have unlocked tasklist_lock. + * Returns zero if the search for a child should continue; + * then ->notask_error is 0 if @p is an eligible child, + * or still -ECHILD. + */ +static int wait_consider_task(struct wait_opts *wo, int ptrace, + struct task_struct *p) +{ + /* + * We can race with wait_task_zombie() from another thread. + * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition + * can't confuse the checks below. + */ + int exit_state = READ_ONCE(p->exit_state); + int ret; + + if (unlikely(exit_state == EXIT_DEAD)) + return 0; + + ret = eligible_child(wo, ptrace, p); + if (!ret) + return ret; + + if (unlikely(exit_state == EXIT_TRACE)) { + /* + * ptrace == 0 means we are the natural parent. In this case + * we should clear notask_error, debugger will notify us. + */ + if (likely(!ptrace)) + wo->notask_error = 0; + return 0; + } + + if (likely(!ptrace) && unlikely(p->ptrace)) { + /* + * If it is traced by its real parent's group, just pretend + * the caller is ptrace_do_wait() and reap this child if it + * is zombie. + * + * This also hides group stop state from real parent; otherwise + * a single stop can be reported twice as group and ptrace stop. + * If a ptracer wants to distinguish these two events for its + * own children it should create a separate process which takes + * the role of real parent. + */ + if (!ptrace_reparented(p)) + ptrace = 1; + } + + /* slay zombie? */ + if (exit_state == EXIT_ZOMBIE) { + /* we don't reap group leaders with subthreads */ + if (!delay_group_leader(p)) { + /* + * A zombie ptracee is only visible to its ptracer. + * Notification and reaping will be cascaded to the + * real parent when the ptracer detaches. + */ + if (unlikely(ptrace) || likely(!p->ptrace)) + return wait_task_zombie(wo, p); + } + + /* + * Allow access to stopped/continued state via zombie by + * falling through. Clearing of notask_error is complex. + * + * When !@ptrace: + * + * If WEXITED is set, notask_error should naturally be + * cleared. If not, subset of WSTOPPED|WCONTINUED is set, + * so, if there are live subthreads, there are events to + * wait for. If all subthreads are dead, it's still safe + * to clear - this function will be called again in finite + * amount time once all the subthreads are released and + * will then return without clearing. + * + * When @ptrace: + * + * Stopped state is per-task and thus can't change once the + * target task dies. Only continued and exited can happen. + * Clear notask_error if WCONTINUED | WEXITED. + */ + if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED))) + wo->notask_error = 0; + } else { + /* + * @p is alive and it's gonna stop, continue or exit, so + * there always is something to wait for. + */ + wo->notask_error = 0; + } + + /* + * Wait for stopped. Depending on @ptrace, different stopped state + * is used and the two don't interact with each other. + */ + ret = wait_task_stopped(wo, ptrace, p); + if (ret) + return ret; + + /* + * Wait for continued. There's only one continued state and the + * ptracer can consume it which can confuse the real parent. Don't + * use WCONTINUED from ptracer. You don't need or want it. + */ + return wait_task_continued(wo, p); +} + +/* + * Do the work of do_wait() for one thread in the group, @tsk. + * + * -ECHILD should be in ->notask_error before the first call. + * Returns nonzero for a final return, when we have unlocked tasklist_lock. + * Returns zero if the search for a child should continue; then + * ->notask_error is 0 if there were any eligible children, + * or still -ECHILD. + */ +static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) +{ + struct task_struct *p; + + list_for_each_entry(p, &tsk->children, sibling) { + int ret = wait_consider_task(wo, 0, p); + + if (ret) + return ret; + } + + return 0; +} + +static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) +{ + struct task_struct *p; + + list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { + int ret = wait_consider_task(wo, 1, p); + + if (ret) + return ret; + } + + return 0; +} + +static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode, + int sync, void *key) +{ + struct wait_opts *wo = container_of(wait, struct wait_opts, + child_wait); + struct task_struct *p = key; + + if (!eligible_pid(wo, p)) + return 0; + + if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) + return 0; + + return default_wake_function(wait, mode, sync, key); +} + +void __wake_up_parent(struct task_struct *p, struct task_struct *parent) +{ + __wake_up_sync_key(&parent->signal->wait_chldexit, + TASK_INTERRUPTIBLE, p); +} + +static bool is_effectively_child(struct wait_opts *wo, bool ptrace, + struct task_struct *target) +{ + struct task_struct *parent = + !ptrace ? target->real_parent : target->parent; + + return current == parent || (!(wo->wo_flags & __WNOTHREAD) && + same_thread_group(current, parent)); +} + +/* + * Optimization for waiting on PIDTYPE_PID. No need to iterate through child + * and tracee lists to find the target task. + */ +static int do_wait_pid(struct wait_opts *wo) +{ + bool ptrace; + struct task_struct *target; + int retval; + + ptrace = false; + target = pid_task(wo->wo_pid, PIDTYPE_TGID); + if (target && is_effectively_child(wo, ptrace, target)) { + retval = wait_consider_task(wo, ptrace, target); + if (retval) + return retval; + } + + ptrace = true; + target = pid_task(wo->wo_pid, PIDTYPE_PID); + if (target && target->ptrace && + is_effectively_child(wo, ptrace, target)) { + retval = wait_consider_task(wo, ptrace, target); + if (retval) + return retval; + } + + return 0; +} + +static long do_wait(struct wait_opts *wo) +{ + int retval; + + trace_sched_process_wait(wo->wo_pid); + + init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); + wo->child_wait.private = current; + add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); +repeat: + /* + * If there is nothing that can match our criteria, just get out. + * We will clear ->notask_error to zero if we see any child that + * might later match our criteria, even if we are not able to reap + * it yet. + */ + wo->notask_error = -ECHILD; + if ((wo->wo_type < PIDTYPE_MAX) && + (!wo->wo_pid || !pid_has_task(wo->wo_pid, wo->wo_type))) + goto notask; + + set_current_state(TASK_INTERRUPTIBLE); + read_lock(&tasklist_lock); + + if (wo->wo_type == PIDTYPE_PID) { + retval = do_wait_pid(wo); + if (retval) + goto end; + } else { + struct task_struct *tsk = current; + + do { + retval = do_wait_thread(wo, tsk); + if (retval) + goto end; + + retval = ptrace_do_wait(wo, tsk); + if (retval) + goto end; + + if (wo->wo_flags & __WNOTHREAD) + break; + } while_each_thread(current, tsk); + } + read_unlock(&tasklist_lock); + +notask: + retval = wo->notask_error; + if (!retval && !(wo->wo_flags & WNOHANG)) { + retval = -ERESTARTSYS; + if (!signal_pending(current)) { + schedule(); + goto repeat; + } + } +end: + __set_current_state(TASK_RUNNING); + remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); + return retval; +} + +static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, + int options, struct rusage *ru) +{ + struct wait_opts wo; + struct pid *pid = NULL; + enum pid_type type; + long ret; + unsigned int f_flags = 0; + + if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED| + __WNOTHREAD|__WCLONE|__WALL)) + return -EINVAL; + if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) + return -EINVAL; + + switch (which) { + case P_ALL: + type = PIDTYPE_MAX; + break; + case P_PID: + type = PIDTYPE_PID; + if (upid <= 0) + return -EINVAL; + + pid = find_get_pid(upid); + break; + case P_PGID: + type = PIDTYPE_PGID; + if (upid < 0) + return -EINVAL; + + if (upid) + pid = find_get_pid(upid); + else + pid = get_task_pid(current, PIDTYPE_PGID); + break; + case P_PIDFD: + type = PIDTYPE_PID; + if (upid < 0) + return -EINVAL; + + pid = pidfd_get_pid(upid, &f_flags); + if (IS_ERR(pid)) + return PTR_ERR(pid); + + break; + default: + return -EINVAL; + } + + wo.wo_type = type; + wo.wo_pid = pid; + wo.wo_flags = options; + wo.wo_info = infop; + wo.wo_rusage = ru; + if (f_flags & O_NONBLOCK) + wo.wo_flags |= WNOHANG; + + ret = do_wait(&wo); + if (!ret && !(options & WNOHANG) && (f_flags & O_NONBLOCK)) + ret = -EAGAIN; + + put_pid(pid); + return ret; +} + +SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, + infop, int, options, struct rusage __user *, ru) +{ + struct rusage r; + struct waitid_info info = {.status = 0}; + long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL); + int signo = 0; + + if (err > 0) { + signo = SIGCHLD; + err = 0; + if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) + return -EFAULT; + } + if (!infop) + return err; + + if (!user_write_access_begin(infop, sizeof(*infop))) + return -EFAULT; + + unsafe_put_user(signo, &infop->si_signo, Efault); + unsafe_put_user(0, &infop->si_errno, Efault); + unsafe_put_user(info.cause, &infop->si_code, Efault); + unsafe_put_user(info.pid, &infop->si_pid, Efault); + unsafe_put_user(info.uid, &infop->si_uid, Efault); + unsafe_put_user(info.status, &infop->si_status, Efault); + user_write_access_end(); + return err; +Efault: + user_write_access_end(); + return -EFAULT; +} + +long kernel_wait4(pid_t upid, int __user *stat_addr, int options, + struct rusage *ru) +{ + struct wait_opts wo; + struct pid *pid = NULL; + enum pid_type type; + long ret; + + if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| + __WNOTHREAD|__WCLONE|__WALL)) + return -EINVAL; + + /* -INT_MIN is not defined */ + if (upid == INT_MIN) + return -ESRCH; + + if (upid == -1) + type = PIDTYPE_MAX; + else if (upid < 0) { + type = PIDTYPE_PGID; + pid = find_get_pid(-upid); + } else if (upid == 0) { + type = PIDTYPE_PGID; + pid = get_task_pid(current, PIDTYPE_PGID); + } else /* upid > 0 */ { + type = PIDTYPE_PID; + pid = find_get_pid(upid); + } + + wo.wo_type = type; + wo.wo_pid = pid; + wo.wo_flags = options | WEXITED; + wo.wo_info = NULL; + wo.wo_stat = 0; + wo.wo_rusage = ru; + ret = do_wait(&wo); + put_pid(pid); + if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr)) + ret = -EFAULT; + + return ret; +} + +int kernel_wait(pid_t pid, int *stat) +{ + struct wait_opts wo = { + .wo_type = PIDTYPE_PID, + .wo_pid = find_get_pid(pid), + .wo_flags = WEXITED, + }; + int ret; + + ret = do_wait(&wo); + if (ret > 0 && wo.wo_stat) + *stat = wo.wo_stat; + put_pid(wo.wo_pid); + return ret; +} + +SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, + int, options, struct rusage __user *, ru) +{ + struct rusage r; + long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL); + + if (err > 0) { + if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) + return -EFAULT; + } + return err; +} + +#ifdef __ARCH_WANT_SYS_WAITPID + +/* + * sys_waitpid() remains for compatibility. waitpid() should be + * implemented by calling sys_wait4() from libc.a. + */ +SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) +{ + return kernel_wait4(pid, stat_addr, options, NULL); +} + +#endif + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE4(wait4, + compat_pid_t, pid, + compat_uint_t __user *, stat_addr, + int, options, + struct compat_rusage __user *, ru) +{ + struct rusage r; + long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL); + if (err > 0) { + if (ru && put_compat_rusage(&r, ru)) + return -EFAULT; + } + return err; +} + +COMPAT_SYSCALL_DEFINE5(waitid, + int, which, compat_pid_t, pid, + struct compat_siginfo __user *, infop, int, options, + struct compat_rusage __user *, uru) +{ + struct rusage ru; + struct waitid_info info = {.status = 0}; + long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL); + int signo = 0; + if (err > 0) { + signo = SIGCHLD; + err = 0; + if (uru) { + /* kernel_waitid() overwrites everything in ru */ + if (COMPAT_USE_64BIT_TIME) + err = copy_to_user(uru, &ru, sizeof(ru)); + else + err = put_compat_rusage(&ru, uru); + if (err) + return -EFAULT; + } + } + + if (!infop) + return err; + + if (!user_write_access_begin(infop, sizeof(*infop))) + return -EFAULT; + + unsafe_put_user(signo, &infop->si_signo, Efault); + unsafe_put_user(0, &infop->si_errno, Efault); + unsafe_put_user(info.cause, &infop->si_code, Efault); + unsafe_put_user(info.pid, &infop->si_pid, Efault); + unsafe_put_user(info.uid, &infop->si_uid, Efault); + unsafe_put_user(info.status, &infop->si_status, Efault); + user_write_access_end(); + return err; +Efault: + user_write_access_end(); + return -EFAULT; +} +#endif + +/** + * thread_group_exited - check that a thread group has exited + * @pid: tgid of thread group to be checked. + * + * Test if the thread group represented by tgid has exited (all + * threads are zombies, dead or completely gone). + * + * Return: true if the thread group has exited. false otherwise. + */ +bool thread_group_exited(struct pid *pid) +{ + struct task_struct *task; + bool exited; + + rcu_read_lock(); + task = pid_task(pid, PIDTYPE_PID); + exited = !task || + (READ_ONCE(task->exit_state) && thread_group_empty(task)); + rcu_read_unlock(); + + return exited; +} +EXPORT_SYMBOL(thread_group_exited); + +/* + * This needs to be __function_aligned as GCC implicitly makes any + * implementation of abort() cold and drops alignment specified by + * -falign-functions=N. + * + * See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88345#c11 + */ +__weak __function_aligned void abort(void) +{ + BUG(); + + /* if that doesn't kill us, halt */ + panic("Oops failed to kill thread"); +} +EXPORT_SYMBOL(abort); |