| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * linux/kernel/signal.c |
| * |
| * Copyright (C) 1991, 1992 Linus Torvalds |
| * |
| * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson |
| * |
| * 2003-06-02 Jim Houston - Concurrent Computer Corp. |
| * Changes to use preallocated sigqueue structures |
| * to allow signals to be sent reliably. |
| */ |
| |
| #include <linux/slab.h> |
| #include <linux/export.h> |
| #include <linux/init.h> |
| #include <linux/sched/mm.h> |
| #include <linux/sched/user.h> |
| #include <linux/sched/debug.h> |
| #include <linux/sched/task.h> |
| #include <linux/sched/task_stack.h> |
| #include <linux/sched/cputime.h> |
| #include <linux/file.h> |
| #include <linux/fs.h> |
| #include <linux/proc_fs.h> |
| #include <linux/tty.h> |
| #include <linux/binfmts.h> |
| #include <linux/coredump.h> |
| #include <linux/security.h> |
| #include <linux/syscalls.h> |
| #include <linux/ptrace.h> |
| #include <linux/signal.h> |
| #include <linux/signalfd.h> |
| #include <linux/ratelimit.h> |
| #include <linux/task_work.h> |
| #include <linux/capability.h> |
| #include <linux/freezer.h> |
| #include <linux/pid_namespace.h> |
| #include <linux/nsproxy.h> |
| #include <linux/user_namespace.h> |
| #include <linux/uprobes.h> |
| #include <linux/compat.h> |
| #include <linux/cn_proc.h> |
| #include <linux/compiler.h> |
| #include <linux/posix-timers.h> |
| #include <linux/cgroup.h> |
| #include <linux/audit.h> |
| #include <linux/oom.h> |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/signal.h> |
| |
| #include <asm/param.h> |
| #include <linux/uaccess.h> |
| #include <asm/unistd.h> |
| #include <asm/siginfo.h> |
| #include <asm/cacheflush.h> |
| #include <asm/syscall.h> /* for syscall_get_* */ |
| |
| #undef CREATE_TRACE_POINTS |
| #include <trace/hooks/signal.h> |
| #include <trace/hooks/dtask.h> |
| /* |
| * SLAB caches for signal bits. |
| */ |
| |
| static struct kmem_cache *sigqueue_cachep; |
| |
| int print_fatal_signals __read_mostly; |
| |
| static void __user *sig_handler(struct task_struct *t, int sig) |
| { |
| return t->sighand->action[sig - 1].sa.sa_handler; |
| } |
| |
| static inline bool sig_handler_ignored(void __user *handler, int sig) |
| { |
| /* Is it explicitly or implicitly ignored? */ |
| return handler == SIG_IGN || |
| (handler == SIG_DFL && sig_kernel_ignore(sig)); |
| } |
| |
| static bool sig_task_ignored(struct task_struct *t, int sig, bool force) |
| { |
| void __user *handler; |
| |
| handler = sig_handler(t, sig); |
| |
| /* SIGKILL and SIGSTOP may not be sent to the global init */ |
| if (unlikely(is_global_init(t) && sig_kernel_only(sig))) |
| return true; |
| |
| if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) && |
| handler == SIG_DFL && !(force && sig_kernel_only(sig))) |
| return true; |
| |
| /* Only allow kernel generated signals to this kthread */ |
| if (unlikely((t->flags & PF_KTHREAD) && |
| (handler == SIG_KTHREAD_KERNEL) && !force)) |
| return true; |
| |
| return sig_handler_ignored(handler, sig); |
| } |
| |
| static bool sig_ignored(struct task_struct *t, int sig, bool force) |
| { |
| /* |
| * Blocked signals are never ignored, since the |
| * signal handler may change by the time it is |
| * unblocked. |
| */ |
| if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig)) |
| return false; |
| |
| /* |
| * Tracers may want to know about even ignored signal unless it |
| * is SIGKILL which can't be reported anyway but can be ignored |
| * by SIGNAL_UNKILLABLE task. |
| */ |
| if (t->ptrace && sig != SIGKILL) |
| return false; |
| |
| return sig_task_ignored(t, sig, force); |
| } |
| |
| /* |
| * Re-calculate pending state from the set of locally pending |
| * signals, globally pending signals, and blocked signals. |
| */ |
| static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked) |
| { |
| unsigned long ready; |
| long i; |
| |
| switch (_NSIG_WORDS) { |
| default: |
| for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;) |
| ready |= signal->sig[i] &~ blocked->sig[i]; |
| break; |
| |
| case 4: ready = signal->sig[3] &~ blocked->sig[3]; |
| ready |= signal->sig[2] &~ blocked->sig[2]; |
| ready |= signal->sig[1] &~ blocked->sig[1]; |
| ready |= signal->sig[0] &~ blocked->sig[0]; |
| break; |
| |
| case 2: ready = signal->sig[1] &~ blocked->sig[1]; |
| ready |= signal->sig[0] &~ blocked->sig[0]; |
| break; |
| |
| case 1: ready = signal->sig[0] &~ blocked->sig[0]; |
| } |
| return ready != 0; |
| } |
| |
| #define PENDING(p,b) has_pending_signals(&(p)->signal, (b)) |
| |
| static bool recalc_sigpending_tsk(struct task_struct *t) |
| { |
| if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) || |
| PENDING(&t->pending, &t->blocked) || |
| PENDING(&t->signal->shared_pending, &t->blocked) || |
| cgroup_task_frozen(t)) { |
| set_tsk_thread_flag(t, TIF_SIGPENDING); |
| return true; |
| } |
| |
| /* |
| * We must never clear the flag in another thread, or in current |
| * when it's possible the current syscall is returning -ERESTART*. |
| * So we don't clear it here, and only callers who know they should do. |
| */ |
| return false; |
| } |
| |
| /* |
| * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up. |
| * This is superfluous when called on current, the wakeup is a harmless no-op. |
| */ |
| void recalc_sigpending_and_wake(struct task_struct *t) |
| { |
| if (recalc_sigpending_tsk(t)) |
| signal_wake_up(t, 0); |
| } |
| |
| void recalc_sigpending(void) |
| { |
| if (!recalc_sigpending_tsk(current) && !freezing(current)) |
| clear_thread_flag(TIF_SIGPENDING); |
| |
| } |
| EXPORT_SYMBOL(recalc_sigpending); |
| |
| void calculate_sigpending(void) |
| { |
| /* Have any signals or users of TIF_SIGPENDING been delayed |
| * until after fork? |
| */ |
| spin_lock_irq(¤t->sighand->siglock); |
| set_tsk_thread_flag(current, TIF_SIGPENDING); |
| recalc_sigpending(); |
| spin_unlock_irq(¤t->sighand->siglock); |
| } |
| |
| /* Given the mask, find the first available signal that should be serviced. */ |
| |
| #define SYNCHRONOUS_MASK \ |
| (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \ |
| sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS)) |
| |
| int next_signal(struct sigpending *pending, sigset_t *mask) |
| { |
| unsigned long i, *s, *m, x; |
| int sig = 0; |
| |
| s = pending->signal.sig; |
| m = mask->sig; |
| |
| /* |
| * Handle the first word specially: it contains the |
| * synchronous signals that need to be dequeued first. |
| */ |
| x = *s &~ *m; |
| if (x) { |
| if (x & SYNCHRONOUS_MASK) |
| x &= SYNCHRONOUS_MASK; |
| sig = ffz(~x) + 1; |
| return sig; |
| } |
| |
| switch (_NSIG_WORDS) { |
| default: |
| for (i = 1; i < _NSIG_WORDS; ++i) { |
| x = *++s &~ *++m; |
| if (!x) |
| continue; |
| sig = ffz(~x) + i*_NSIG_BPW + 1; |
| break; |
| } |
| break; |
| |
| case 2: |
| x = s[1] &~ m[1]; |
| if (!x) |
| break; |
| sig = ffz(~x) + _NSIG_BPW + 1; |
| break; |
| |
| case 1: |
| /* Nothing to do */ |
| break; |
| } |
| |
| return sig; |
| } |
| |
| static inline void print_dropped_signal(int sig) |
| { |
| static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10); |
| |
| if (!print_fatal_signals) |
| return; |
| |
| if (!__ratelimit(&ratelimit_state)) |
| return; |
| |
| pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n", |
| current->comm, current->pid, sig); |
| } |
| |
| /** |
| * task_set_jobctl_pending - set jobctl pending bits |
| * @task: target task |
| * @mask: pending bits to set |
| * |
| * Clear @mask from @task->jobctl. @mask must be subset of |
| * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK | |
| * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is |
| * cleared. If @task is already being killed or exiting, this function |
| * becomes noop. |
| * |
| * CONTEXT: |
| * Must be called with @task->sighand->siglock held. |
| * |
| * RETURNS: |
| * %true if @mask is set, %false if made noop because @task was dying. |
| */ |
| bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask) |
| { |
| BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME | |
| JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING)); |
| BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK)); |
| |
| if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING))) |
| return false; |
| |
| if (mask & JOBCTL_STOP_SIGMASK) |
| task->jobctl &= ~JOBCTL_STOP_SIGMASK; |
| |
| task->jobctl |= mask; |
| return true; |
| } |
| |
| /** |
| * task_clear_jobctl_trapping - clear jobctl trapping bit |
| * @task: target task |
| * |
| * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED. |
| * Clear it and wake up the ptracer. Note that we don't need any further |
| * locking. @task->siglock guarantees that @task->parent points to the |
| * ptracer. |
| * |
| * CONTEXT: |
| * Must be called with @task->sighand->siglock held. |
| */ |
| void task_clear_jobctl_trapping(struct task_struct *task) |
| { |
| if (unlikely(task->jobctl & JOBCTL_TRAPPING)) { |
| task->jobctl &= ~JOBCTL_TRAPPING; |
| smp_mb(); /* advised by wake_up_bit() */ |
| wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT); |
| } |
| } |
| |
| /** |
| * task_clear_jobctl_pending - clear jobctl pending bits |
| * @task: target task |
| * @mask: pending bits to clear |
| * |
| * Clear @mask from @task->jobctl. @mask must be subset of |
| * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other |
| * STOP bits are cleared together. |
| * |
| * If clearing of @mask leaves no stop or trap pending, this function calls |
| * task_clear_jobctl_trapping(). |
| * |
| * CONTEXT: |
| * Must be called with @task->sighand->siglock held. |
| */ |
| void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask) |
| { |
| BUG_ON(mask & ~JOBCTL_PENDING_MASK); |
| |
| if (mask & JOBCTL_STOP_PENDING) |
| mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED; |
| |
| task->jobctl &= ~mask; |
| |
| if (!(task->jobctl & JOBCTL_PENDING_MASK)) |
| task_clear_jobctl_trapping(task); |
| } |
| |
| /** |
| * task_participate_group_stop - participate in a group stop |
| * @task: task participating in a group stop |
| * |
| * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop. |
| * Group stop states are cleared and the group stop count is consumed if |
| * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group |
| * stop, the appropriate `SIGNAL_*` flags are set. |
| * |
| * CONTEXT: |
| * Must be called with @task->sighand->siglock held. |
| * |
| * RETURNS: |
| * %true if group stop completion should be notified to the parent, %false |
| * otherwise. |
| */ |
| static bool task_participate_group_stop(struct task_struct *task) |
| { |
| struct signal_struct *sig = task->signal; |
| bool consume = task->jobctl & JOBCTL_STOP_CONSUME; |
| |
| WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING)); |
| |
| task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING); |
| |
| if (!consume) |
| return false; |
| |
| if (!WARN_ON_ONCE(sig->group_stop_count == 0)) |
| sig->group_stop_count--; |
| |
| /* |
| * Tell the caller to notify completion iff we are entering into a |
| * fresh group stop. Read comment in do_signal_stop() for details. |
| */ |
| if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) { |
| signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED); |
| return true; |
| } |
| return false; |
| } |
| |
| void task_join_group_stop(struct task_struct *task) |
| { |
| unsigned long mask = current->jobctl & JOBCTL_STOP_SIGMASK; |
| struct signal_struct *sig = current->signal; |
| |
| if (sig->group_stop_count) { |
| sig->group_stop_count++; |
| mask |= JOBCTL_STOP_CONSUME; |
| } else if (!(sig->flags & SIGNAL_STOP_STOPPED)) |
| return; |
| |
| /* Have the new thread join an on-going signal group stop */ |
| task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING); |
| } |
| |
| /* |
| * allocate a new signal queue record |
| * - this may be called without locks if and only if t == current, otherwise an |
| * appropriate lock must be held to stop the target task from exiting |
| */ |
| static struct sigqueue * |
| __sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags, |
| int override_rlimit, const unsigned int sigqueue_flags) |
| { |
| struct sigqueue *q = NULL; |
| struct ucounts *ucounts = NULL; |
| long sigpending; |
| |
| /* |
| * Protect access to @t credentials. This can go away when all |
| * callers hold rcu read lock. |
| * |
| * NOTE! A pending signal will hold on to the user refcount, |
| * and we get/put the refcount only when the sigpending count |
| * changes from/to zero. |
| */ |
| rcu_read_lock(); |
| ucounts = task_ucounts(t); |
| sigpending = inc_rlimit_get_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING); |
| rcu_read_unlock(); |
| if (!sigpending) |
| return NULL; |
| |
| if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) { |
| q = kmem_cache_alloc(sigqueue_cachep, gfp_flags); |
| } else { |
| print_dropped_signal(sig); |
| } |
| |
| if (unlikely(q == NULL)) { |
| dec_rlimit_put_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING); |
| } else { |
| INIT_LIST_HEAD(&q->list); |
| q->flags = sigqueue_flags; |
| q->ucounts = ucounts; |
| } |
| return q; |
| } |
| |
| static void __sigqueue_free(struct sigqueue *q) |
| { |
| if (q->flags & SIGQUEUE_PREALLOC) |
| return; |
| if (q->ucounts) { |
| dec_rlimit_put_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING); |
| q->ucounts = NULL; |
| } |
| kmem_cache_free(sigqueue_cachep, q); |
| } |
| |
| void flush_sigqueue(struct sigpending *queue) |
| { |
| struct sigqueue *q; |
| |
| sigemptyset(&queue->signal); |
| while (!list_empty(&queue->list)) { |
| q = list_entry(queue->list.next, struct sigqueue , list); |
| list_del_init(&q->list); |
| __sigqueue_free(q); |
| } |
| } |
| |
| /* |
| * Flush all pending signals for this kthread. |
| */ |
| void flush_signals(struct task_struct *t) |
| { |
| unsigned long flags; |
| |
| spin_lock_irqsave(&t->sighand->siglock, flags); |
| clear_tsk_thread_flag(t, TIF_SIGPENDING); |
| flush_sigqueue(&t->pending); |
| flush_sigqueue(&t->signal->shared_pending); |
| spin_unlock_irqrestore(&t->sighand->siglock, flags); |
| } |
| EXPORT_SYMBOL(flush_signals); |
| |
| #ifdef CONFIG_POSIX_TIMERS |
| static void __flush_itimer_signals(struct sigpending *pending) |
| { |
| sigset_t signal, retain; |
| struct sigqueue *q, *n; |
| |
| signal = pending->signal; |
| sigemptyset(&retain); |
| |
| list_for_each_entry_safe(q, n, &pending->list, list) { |
| int sig = q->info.si_signo; |
| |
| if (likely(q->info.si_code != SI_TIMER)) { |
| sigaddset(&retain, sig); |
| } else { |
| sigdelset(&signal, sig); |
| list_del_init(&q->list); |
| __sigqueue_free(q); |
| } |
| } |
| |
| sigorsets(&pending->signal, &signal, &retain); |
| } |
| |
| void flush_itimer_signals(void) |
| { |
| struct task_struct *tsk = current; |
| unsigned long flags; |
| |
| spin_lock_irqsave(&tsk->sighand->siglock, flags); |
| __flush_itimer_signals(&tsk->pending); |
| __flush_itimer_signals(&tsk->signal->shared_pending); |
| spin_unlock_irqrestore(&tsk->sighand->siglock, flags); |
| } |
| #endif |
| |
| void ignore_signals(struct task_struct *t) |
| { |
| int i; |
| |
| for (i = 0; i < _NSIG; ++i) |
| t->sighand->action[i].sa.sa_handler = SIG_IGN; |
| |
| flush_signals(t); |
| } |
| |
| /* |
| * Flush all handlers for a task. |
| */ |
| |
| void |
| flush_signal_handlers(struct task_struct *t, int force_default) |
| { |
| int i; |
| struct k_sigaction *ka = &t->sighand->action[0]; |
| for (i = _NSIG ; i != 0 ; i--) { |
| if (force_default || ka->sa.sa_handler != SIG_IGN) |
| ka->sa.sa_handler = SIG_DFL; |
| ka->sa.sa_flags = 0; |
| #ifdef __ARCH_HAS_SA_RESTORER |
| ka->sa.sa_restorer = NULL; |
| #endif |
| sigemptyset(&ka->sa.sa_mask); |
| ka++; |
| } |
| } |
| |
| bool unhandled_signal(struct task_struct *tsk, int sig) |
| { |
| void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler; |
| if (is_global_init(tsk)) |
| return true; |
| |
| if (handler != SIG_IGN && handler != SIG_DFL) |
| return false; |
| |
| /* If dying, we handle all new signals by ignoring them */ |
| if (fatal_signal_pending(tsk)) |
| return false; |
| |
| /* if ptraced, let the tracer determine */ |
| return !tsk->ptrace; |
| } |
| |
| static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *info, |
| bool *resched_timer) |
| { |
| struct sigqueue *q, *first = NULL; |
| |
| /* |
| * Collect the siginfo appropriate to this signal. Check if |
| * there is another siginfo for the same signal. |
| */ |
| list_for_each_entry(q, &list->list, list) { |
| if (q->info.si_signo == sig) { |
| if (first) |
| goto still_pending; |
| first = q; |
| } |
| } |
| |
| sigdelset(&list->signal, sig); |
| |
| if (first) { |
| still_pending: |
| list_del_init(&first->list); |
| copy_siginfo(info, &first->info); |
| |
| *resched_timer = |
| (first->flags & SIGQUEUE_PREALLOC) && |
| (info->si_code == SI_TIMER) && |
| (info->si_sys_private); |
| |
| __sigqueue_free(first); |
| } else { |
| /* |
| * Ok, it wasn't in the queue. This must be |
| * a fast-pathed signal or we must have been |
| * out of queue space. So zero out the info. |
| */ |
| clear_siginfo(info); |
| info->si_signo = sig; |
| info->si_errno = 0; |
| info->si_code = SI_USER; |
| info->si_pid = 0; |
| info->si_uid = 0; |
| } |
| } |
| |
| static int __dequeue_signal(struct sigpending *pending, sigset_t *mask, |
| kernel_siginfo_t *info, bool *resched_timer) |
| { |
| int sig = next_signal(pending, mask); |
| |
| if (sig) |
| collect_signal(sig, pending, info, resched_timer); |
| return sig; |
| } |
| |
| /* |
| * Dequeue a signal and return the element to the caller, which is |
| * expected to free it. |
| * |
| * All callers have to hold the siglock. |
| */ |
| int dequeue_signal(struct task_struct *tsk, sigset_t *mask, |
| kernel_siginfo_t *info, enum pid_type *type) |
| { |
| bool resched_timer = false; |
| int signr; |
| |
| /* We only dequeue private signals from ourselves, we don't let |
| * signalfd steal them |
| */ |
| *type = PIDTYPE_PID; |
| signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer); |
| if (!signr) { |
| *type = PIDTYPE_TGID; |
| signr = __dequeue_signal(&tsk->signal->shared_pending, |
| mask, info, &resched_timer); |
| #ifdef CONFIG_POSIX_TIMERS |
| /* |
| * itimer signal ? |
| * |
| * itimers are process shared and we restart periodic |
| * itimers in the signal delivery path to prevent DoS |
| * attacks in the high resolution timer case. This is |
| * compliant with the old way of self-restarting |
| * itimers, as the SIGALRM is a legacy signal and only |
| * queued once. Changing the restart behaviour to |
| * restart the timer in the signal dequeue path is |
| * reducing the timer noise on heavy loaded !highres |
| * systems too. |
| */ |
| if (unlikely(signr == SIGALRM)) { |
| struct hrtimer *tmr = &tsk->signal->real_timer; |
| |
| if (!hrtimer_is_queued(tmr) && |
| tsk->signal->it_real_incr != 0) { |
| hrtimer_forward(tmr, tmr->base->get_time(), |
| tsk->signal->it_real_incr); |
| hrtimer_restart(tmr); |
| } |
| } |
| #endif |
| } |
| |
| recalc_sigpending(); |
| if (!signr) |
| return 0; |
| |
| if (unlikely(sig_kernel_stop(signr))) { |
| /* |
| * Set a marker that we have dequeued a stop signal. Our |
| * caller might release the siglock and then the pending |
| * stop signal it is about to process is no longer in the |
| * pending bitmasks, but must still be cleared by a SIGCONT |
| * (and overruled by a SIGKILL). So those cases clear this |
| * shared flag after we've set it. Note that this flag may |
| * remain set after the signal we return is ignored or |
| * handled. That doesn't matter because its only purpose |
| * is to alert stop-signal processing code when another |
| * processor has come along and cleared the flag. |
| */ |
| current->jobctl |= JOBCTL_STOP_DEQUEUED; |
| } |
| #ifdef CONFIG_POSIX_TIMERS |
| if (resched_timer) { |
| /* |
| * Release the siglock to ensure proper locking order |
| * of timer locks outside of siglocks. Note, we leave |
| * irqs disabled here, since the posix-timers code is |
| * about to disable them again anyway. |
| */ |
| spin_unlock(&tsk->sighand->siglock); |
| posixtimer_rearm(info); |
| spin_lock(&tsk->sighand->siglock); |
| |
| /* Don't expose the si_sys_private value to userspace */ |
| info->si_sys_private = 0; |
| } |
| #endif |
| return signr; |
| } |
| EXPORT_SYMBOL_GPL(dequeue_signal); |
| |
| static int dequeue_synchronous_signal(kernel_siginfo_t *info) |
| { |
| struct task_struct *tsk = current; |
| struct sigpending *pending = &tsk->pending; |
| struct sigqueue *q, *sync = NULL; |
| |
| /* |
| * Might a synchronous signal be in the queue? |
| */ |
| if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK)) |
| return 0; |
| |
| /* |
| * Return the first synchronous signal in the queue. |
| */ |
| list_for_each_entry(q, &pending->list, list) { |
| /* Synchronous signals have a positive si_code */ |
| if ((q->info.si_code > SI_USER) && |
| (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) { |
| sync = q; |
| goto next; |
| } |
| } |
| return 0; |
| next: |
| /* |
| * Check if there is another siginfo for the same signal. |
| */ |
| list_for_each_entry_continue(q, &pending->list, list) { |
| if (q->info.si_signo == sync->info.si_signo) |
| goto still_pending; |
| } |
| |
| sigdelset(&pending->signal, sync->info.si_signo); |
| recalc_sigpending(); |
| still_pending: |
| list_del_init(&sync->list); |
| copy_siginfo(info, &sync->info); |
| __sigqueue_free(sync); |
| return info->si_signo; |
| } |
| |
| /* |
| * Tell a process that it has a new active signal.. |
| * |
| * NOTE! we rely on the previous spin_lock to |
| * lock interrupts for us! We can only be called with |
| * "siglock" held, and the local interrupt must |
| * have been disabled when that got acquired! |
| * |
| * No need to set need_resched since signal event passing |
| * goes through ->blocked |
| */ |
| void signal_wake_up_state(struct task_struct *t, unsigned int state) |
| { |
| lockdep_assert_held(&t->sighand->siglock); |
| |
| set_tsk_thread_flag(t, TIF_SIGPENDING); |
| |
| /* |
| * TASK_WAKEKILL also means wake it up in the stopped/traced/killable |
| * case. We don't check t->state here because there is a race with it |
| * executing another processor and just now entering stopped state. |
| * By using wake_up_state, we ensure the process will wake up and |
| * handle its death signal. |
| */ |
| if (!wake_up_state(t, state | TASK_INTERRUPTIBLE)) |
| kick_process(t); |
| } |
| |
| /* |
| * Remove signals in mask from the pending set and queue. |
| * Returns 1 if any signals were found. |
| * |
| * All callers must be holding the siglock. |
| */ |
| static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s) |
| { |
| struct sigqueue *q, *n; |
| sigset_t m; |
| |
| sigandsets(&m, mask, &s->signal); |
| if (sigisemptyset(&m)) |
| return; |
| |
| sigandnsets(&s->signal, &s->signal, mask); |
| list_for_each_entry_safe(q, n, &s->list, list) { |
| if (sigismember(mask, q->info.si_signo)) { |
| list_del_init(&q->list); |
| __sigqueue_free(q); |
| } |
| } |
| } |
| |
| static inline int is_si_special(const struct kernel_siginfo *info) |
| { |
| return info <= SEND_SIG_PRIV; |
| } |
| |
| static inline bool si_fromuser(const struct kernel_siginfo *info) |
| { |
| return info == SEND_SIG_NOINFO || |
| (!is_si_special(info) && SI_FROMUSER(info)); |
| } |
| |
| /* |
| * called with RCU read lock from check_kill_permission() |
| */ |
| static bool kill_ok_by_cred(struct task_struct *t) |
| { |
| const struct cred *cred = current_cred(); |
| const struct cred *tcred = __task_cred(t); |
| |
| return uid_eq(cred->euid, tcred->suid) || |
| uid_eq(cred->euid, tcred->uid) || |
| uid_eq(cred->uid, tcred->suid) || |
| uid_eq(cred->uid, tcred->uid) || |
| ns_capable(tcred->user_ns, CAP_KILL); |
| } |
| |
| /* |
| * Bad permissions for sending the signal |
| * - the caller must hold the RCU read lock |
| */ |
| static int check_kill_permission(int sig, struct kernel_siginfo *info, |
| struct task_struct *t) |
| { |
| struct pid *sid; |
| int error; |
| |
| if (!valid_signal(sig)) |
| return -EINVAL; |
| |
| if (!si_fromuser(info)) |
| return 0; |
| |
| error = audit_signal_info(sig, t); /* Let audit system see the signal */ |
| if (error) |
| return error; |
| |
| if (!same_thread_group(current, t) && |
| !kill_ok_by_cred(t)) { |
| switch (sig) { |
| case SIGCONT: |
| sid = task_session(t); |
| /* |
| * We don't return the error if sid == NULL. The |
| * task was unhashed, the caller must notice this. |
| */ |
| if (!sid || sid == task_session(current)) |
| break; |
| fallthrough; |
| default: |
| return -EPERM; |
| } |
| } |
| |
| return security_task_kill(t, info, sig, NULL); |
| } |
| |
| /** |
| * ptrace_trap_notify - schedule trap to notify ptracer |
| * @t: tracee wanting to notify tracer |
| * |
| * This function schedules sticky ptrace trap which is cleared on the next |
| * TRAP_STOP to notify ptracer of an event. @t must have been seized by |
| * ptracer. |
| * |
| * If @t is running, STOP trap will be taken. If trapped for STOP and |
| * ptracer is listening for events, tracee is woken up so that it can |
| * re-trap for the new event. If trapped otherwise, STOP trap will be |
| * eventually taken without returning to userland after the existing traps |
| * are finished by PTRACE_CONT. |
| * |
| * CONTEXT: |
| * Must be called with @task->sighand->siglock held. |
| */ |
| static void ptrace_trap_notify(struct task_struct *t) |
| { |
| WARN_ON_ONCE(!(t->ptrace & PT_SEIZED)); |
| lockdep_assert_held(&t->sighand->siglock); |
| |
| task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY); |
| ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING); |
| } |
| |
| /* |
| * Handle magic process-wide effects of stop/continue signals. Unlike |
| * the signal actions, these happen immediately at signal-generation |
| * time regardless of blocking, ignoring, or handling. This does the |
| * actual continuing for SIGCONT, but not the actual stopping for stop |
| * signals. The process stop is done as a signal action for SIG_DFL. |
| * |
| * Returns true if the signal should be actually delivered, otherwise |
| * it should be dropped. |
| */ |
| static bool prepare_signal(int sig, struct task_struct *p, bool force) |
| { |
| struct signal_struct *signal = p->signal; |
| struct task_struct *t; |
| sigset_t flush; |
| |
| if (signal->flags & SIGNAL_GROUP_EXIT) { |
| if (signal->core_state) |
| return sig == SIGKILL; |
| /* |
| * The process is in the middle of dying, drop the signal. |
| */ |
| return false; |
| } else if (sig_kernel_stop(sig)) { |
| /* |
| * This is a stop signal. Remove SIGCONT from all queues. |
| */ |
| siginitset(&flush, sigmask(SIGCONT)); |
| flush_sigqueue_mask(&flush, &signal->shared_pending); |
| for_each_thread(p, t) |
| flush_sigqueue_mask(&flush, &t->pending); |
| } else if (sig == SIGCONT) { |
| unsigned int why; |
| /* |
| * Remove all stop signals from all queues, wake all threads. |
| */ |
| siginitset(&flush, SIG_KERNEL_STOP_MASK); |
| flush_sigqueue_mask(&flush, &signal->shared_pending); |
| for_each_thread(p, t) { |
| flush_sigqueue_mask(&flush, &t->pending); |
| task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING); |
| if (likely(!(t->ptrace & PT_SEIZED))) { |
| t->jobctl &= ~JOBCTL_STOPPED; |
| wake_up_state(t, __TASK_STOPPED); |
| } else |
| ptrace_trap_notify(t); |
| } |
| |
| /* |
| * Notify the parent with CLD_CONTINUED if we were stopped. |
| * |
| * If we were in the middle of a group stop, we pretend it |
| * was already finished, and then continued. Since SIGCHLD |
| * doesn't queue we report only CLD_STOPPED, as if the next |
| * CLD_CONTINUED was dropped. |
| */ |
| why = 0; |
| if (signal->flags & SIGNAL_STOP_STOPPED) |
| why |= SIGNAL_CLD_CONTINUED; |
| else if (signal->group_stop_count) |
| why |= SIGNAL_CLD_STOPPED; |
| |
| if (why) { |
| /* |
| * The first thread which returns from do_signal_stop() |
| * will take ->siglock, notice SIGNAL_CLD_MASK, and |
| * notify its parent. See get_signal(). |
| */ |
| signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED); |
| signal->group_stop_count = 0; |
| signal->group_exit_code = 0; |
| } |
| } |
| |
| return !sig_ignored(p, sig, force); |
| } |
| |
| /* |
| * Test if P wants to take SIG. After we've checked all threads with this, |
| * it's equivalent to finding no threads not blocking SIG. Any threads not |
| * blocking SIG were ruled out because they are not running and already |
| * have pending signals. Such threads will dequeue from the shared queue |
| * as soon as they're available, so putting the signal on the shared queue |
| * will be equivalent to sending it to one such thread. |
| */ |
| static inline bool wants_signal(int sig, struct task_struct *p) |
| { |
| if (sigismember(&p->blocked, sig)) |
| return false; |
| |
| if (p->flags & PF_EXITING) |
| return false; |
| |
| if (sig == SIGKILL) |
| return true; |
| |
| if (task_is_stopped_or_traced(p)) |
| return false; |
| |
| return task_curr(p) || !task_sigpending(p); |
| } |
| |
| static void complete_signal(int sig, struct task_struct *p, enum pid_type type) |
| { |
| struct signal_struct *signal = p->signal; |
| struct task_struct *t; |
| bool wake; |
| |
| /* |
| * Now find a thread we can wake up to take the signal off the queue. |
| * |
| * If the main thread wants the signal, it gets first crack. |
| * Probably the least surprising to the average bear. |
| */ |
| if (wants_signal(sig, p)) |
| t = p; |
| else if ((type == PIDTYPE_PID) || thread_group_empty(p)) |
| /* |
| * There is just one thread and it does not need to be woken. |
| * It will dequeue unblocked signals before it runs again. |
| */ |
| return; |
| else { |
| /* |
| * Otherwise try to find a suitable thread. |
| */ |
| t = signal->curr_target; |
| while (!wants_signal(sig, t)) { |
| t = next_thread(t); |
| if (t == signal->curr_target) |
| /* |
| * No thread needs to be woken. |
| * Any eligible threads will see |
| * the signal in the queue soon. |
| */ |
| return; |
| } |
| signal->curr_target = t; |
| } |
| |
| /* |
| * Found a killable thread. If the signal will be fatal, |
| * then start taking the whole group down immediately. |
| */ |
| if (sig_fatal(p, sig) && |
| (signal->core_state || !(signal->flags & SIGNAL_GROUP_EXIT)) && |
| !sigismember(&t->real_blocked, sig) && |
| (sig == SIGKILL || !p->ptrace)) { |
| /* |
| * This signal will be fatal to the whole group. |
| */ |
| if (!sig_kernel_coredump(sig)) { |
| /* |
| * Start a group exit and wake everybody up. |
| * This way we don't have other threads |
| * running and doing things after a slower |
| * thread has the fatal signal pending. |
| */ |
| signal->flags = SIGNAL_GROUP_EXIT; |
| signal->group_exit_code = sig; |
| signal->group_stop_count = 0; |
| t = p; |
| do { |
| trace_android_vh_exit_signal(t); |
| task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); |
| sigaddset(&t->pending.signal, SIGKILL); |
| wake = true; |
| trace_android_vh_exit_signal_whether_wake(t, &wake); |
| if (wake) |
| signal_wake_up(t, 1); |
| } while_each_thread(p, t); |
| return; |
| } |
| } |
| |
| /* |
| * The signal is already in the shared-pending queue. |
| * Tell the chosen thread to wake up and dequeue it. |
| */ |
| signal_wake_up(t, sig == SIGKILL); |
| return; |
| } |
| |
| static inline bool legacy_queue(struct sigpending *signals, int sig) |
| { |
| return (sig < SIGRTMIN) && sigismember(&signals->signal, sig); |
| } |
| |
| static int __send_signal_locked(int sig, struct kernel_siginfo *info, |
| struct task_struct *t, enum pid_type type, bool force) |
| { |
| struct sigpending *pending; |
| struct sigqueue *q; |
| int override_rlimit; |
| int ret = 0, result; |
| |
| lockdep_assert_held(&t->sighand->siglock); |
| |
| result = TRACE_SIGNAL_IGNORED; |
| if (!prepare_signal(sig, t, force)) |
| goto ret; |
| |
| pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending; |
| /* |
| * Short-circuit ignored signals and support queuing |
| * exactly one non-rt signal, so that we can get more |
| * detailed information about the cause of the signal. |
| */ |
| result = TRACE_SIGNAL_ALREADY_PENDING; |
| if (legacy_queue(pending, sig)) |
| goto ret; |
| |
| result = TRACE_SIGNAL_DELIVERED; |
| /* |
| * Skip useless siginfo allocation for SIGKILL and kernel threads. |
| */ |
| if ((sig == SIGKILL) || (t->flags & PF_KTHREAD)) |
| goto out_set; |
| |
| /* |
| * Real-time signals must be queued if sent by sigqueue, or |
| * some other real-time mechanism. It is implementation |
| * defined whether kill() does so. We attempt to do so, on |
| * the principle of least surprise, but since kill is not |
| * allowed to fail with EAGAIN when low on memory we just |
| * make sure at least one signal gets delivered and don't |
| * pass on the info struct. |
| */ |
| if (sig < SIGRTMIN) |
| override_rlimit = (is_si_special(info) || info->si_code >= 0); |
| else |
| override_rlimit = 0; |
| |
| q = __sigqueue_alloc(sig, t, GFP_ATOMIC, override_rlimit, 0); |
| |
| if (q) { |
| list_add_tail(&q->list, &pending->list); |
| switch ((unsigned long) info) { |
| case (unsigned long) SEND_SIG_NOINFO: |
| clear_siginfo(&q->info); |
| q->info.si_signo = sig; |
| q->info.si_errno = 0; |
| q->info.si_code = SI_USER; |
| q->info.si_pid = task_tgid_nr_ns(current, |
| task_active_pid_ns(t)); |
| rcu_read_lock(); |
| q->info.si_uid = |
| from_kuid_munged(task_cred_xxx(t, user_ns), |
| current_uid()); |
| rcu_read_unlock(); |
| break; |
| case (unsigned long) SEND_SIG_PRIV: |
| clear_siginfo(&q->info); |
| q->info.si_signo = sig; |
| q->info.si_errno = 0; |
| q->info.si_code = SI_KERNEL; |
| q->info.si_pid = 0; |
| q->info.si_uid = 0; |
| break; |
| default: |
| copy_siginfo(&q->info, info); |
| break; |
| } |
| } else if (!is_si_special(info) && |
| sig >= SIGRTMIN && info->si_code != SI_USER) { |
| /* |
| * Queue overflow, abort. We may abort if the |
| * signal was rt and sent by user using something |
| * other than kill(). |
| */ |
| result = TRACE_SIGNAL_OVERFLOW_FAIL; |
| ret = -EAGAIN; |
| goto ret; |
| } else { |
| /* |
| * This is a silent loss of information. We still |
| * send the signal, but the *info bits are lost. |
| */ |
| result = TRACE_SIGNAL_LOSE_INFO; |
| } |
| |
| out_set: |
| signalfd_notify(t, sig); |
| sigaddset(&pending->signal, sig); |
| |
| /* Let multiprocess signals appear after on-going forks */ |
| if (type > PIDTYPE_TGID) { |
| struct multiprocess_signals *delayed; |
| hlist_for_each_entry(delayed, &t->signal->multiprocess, node) { |
| sigset_t *signal = &delayed->signal; |
| /* Can't queue both a stop and a continue signal */ |
| if (sig == SIGCONT) |
| sigdelsetmask(signal, SIG_KERNEL_STOP_MASK); |
| else if (sig_kernel_stop(sig)) |
| sigdelset(signal, SIGCONT); |
| sigaddset(signal, sig); |
| } |
| } |
| |
| complete_signal(sig, t, type); |
| ret: |
| trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result); |
| return ret; |
| } |
| |
| static inline bool has_si_pid_and_uid(struct kernel_siginfo *info) |
| { |
| bool ret = false; |
| switch (siginfo_layout(info->si_signo, info->si_code)) { |
| case SIL_KILL: |
| case SIL_CHLD: |
| case SIL_RT: |
| ret = true; |
| break; |
| case SIL_TIMER: |
| case SIL_POLL: |
| case SIL_FAULT: |
| case SIL_FAULT_TRAPNO: |
| case SIL_FAULT_MCEERR: |
| case SIL_FAULT_BNDERR: |
| case SIL_FAULT_PKUERR: |
| case SIL_FAULT_PERF_EVENT: |
| case SIL_SYS: |
| ret = false; |
| break; |
| } |
| return ret; |
| } |
| |
| int send_signal_locked(int sig, struct kernel_siginfo *info, |
| struct task_struct *t, enum pid_type type) |
| { |
| /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */ |
| bool force = false; |
| |
| if (info == SEND_SIG_NOINFO) { |
| /* Force if sent from an ancestor pid namespace */ |
| force = !task_pid_nr_ns(current, task_active_pid_ns(t)); |
| } else if (info == SEND_SIG_PRIV) { |
| /* Don't ignore kernel generated signals */ |
| force = true; |
| } else if (has_si_pid_and_uid(info)) { |
| /* SIGKILL and SIGSTOP is special or has ids */ |
| struct user_namespace *t_user_ns; |
| |
| rcu_read_lock(); |
| t_user_ns = task_cred_xxx(t, user_ns); |
| if (current_user_ns() != t_user_ns) { |
| kuid_t uid = make_kuid(current_user_ns(), info->si_uid); |
| info->si_uid = from_kuid_munged(t_user_ns, uid); |
| } |
| rcu_read_unlock(); |
| |
| /* A kernel generated signal? */ |
| force = (info->si_code == SI_KERNEL); |
| |
| /* From an ancestor pid namespace? */ |
| if (!task_pid_nr_ns(current, task_active_pid_ns(t))) { |
| info->si_pid = 0; |
| force = true; |
| } |
| } |
| return __send_signal_locked(sig, info, t, type, force); |
| } |
| |
| static void print_fatal_signal(int signr) |
| { |
| struct pt_regs *regs = signal_pt_regs(); |
| pr_info("potentially unexpected fatal signal %d.\n", signr); |
| |
| #if defined(__i386__) && !defined(__arch_um__) |
| pr_info("code at %08lx: ", regs->ip); |
| { |
| int i; |
| for (i = 0; i < 16; i++) { |
| unsigned char insn; |
| |
| if (get_user(insn, (unsigned char *)(regs->ip + i))) |
| break; |
| pr_cont("%02x ", insn); |
| } |
| } |
| pr_cont("\n"); |
| #endif |
| preempt_disable(); |
| show_regs(regs); |
| preempt_enable(); |
| } |
| |
| static int __init setup_print_fatal_signals(char *str) |
| { |
| get_option (&str, &print_fatal_signals); |
| |
| return 1; |
| } |
| |
| __setup("print-fatal-signals=", setup_print_fatal_signals); |
| |
| int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p, |
| enum pid_type type) |
| { |
| unsigned long flags; |
| int ret = -ESRCH; |
| trace_android_vh_do_send_sig_info(sig, current, p); |
| if (lock_task_sighand(p, &flags)) { |
| ret = send_signal_locked(sig, info, p, type); |
| unlock_task_sighand(p, &flags); |
| } |
| |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(do_send_sig_info); |
| |
| enum sig_handler { |
| HANDLER_CURRENT, /* If reachable use the current handler */ |
| HANDLER_SIG_DFL, /* Always use SIG_DFL handler semantics */ |
| HANDLER_EXIT, /* Only visible as the process exit code */ |
| }; |
| |
| /* |
| * Force a signal that the process can't ignore: if necessary |
| * we unblock the signal and change any SIG_IGN to SIG_DFL. |
| * |
| * Note: If we unblock the signal, we always reset it to SIG_DFL, |
| * since we do not want to have a signal handler that was blocked |
| * be invoked when user space had explicitly blocked it. |
| * |
| * We don't want to have recursive SIGSEGV's etc, for example, |
| * that is why we also clear SIGNAL_UNKILLABLE. |
| */ |
| static int |
| force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t, |
| enum sig_handler handler) |
| { |
| unsigned long int flags; |
| int ret, blocked, ignored; |
| struct k_sigaction *action; |
| int sig = info->si_signo; |
| |
| spin_lock_irqsave(&t->sighand->siglock, flags); |
| action = &t->sighand->action[sig-1]; |
| ignored = action->sa.sa_handler == SIG_IGN; |
| blocked = sigismember(&t->blocked, sig); |
| if (blocked || ignored || (handler != HANDLER_CURRENT)) { |
| action->sa.sa_handler = SIG_DFL; |
| if (handler == HANDLER_EXIT) |
| action->sa.sa_flags |= SA_IMMUTABLE; |
| if (blocked) { |
| sigdelset(&t->blocked, sig); |
| recalc_sigpending_and_wake(t); |
| } |
| } |
| /* |
| * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect |
| * debugging to leave init killable. But HANDLER_EXIT is always fatal. |
| */ |
| if (action->sa.sa_handler == SIG_DFL && |
| (!t->ptrace || (handler == HANDLER_EXIT))) |
| t->signal->flags &= ~SIGNAL_UNKILLABLE; |
| ret = send_signal_locked(sig, info, t, PIDTYPE_PID); |
| spin_unlock_irqrestore(&t->sighand->siglock, flags); |
| |
| return ret; |
| } |
| |
| int force_sig_info(struct kernel_siginfo *info) |
| { |
| return force_sig_info_to_task(info, current, HANDLER_CURRENT); |
| } |
| |
| /* |
| * Nuke all other threads in the group. |
| */ |
| int zap_other_threads(struct task_struct *p) |
| { |
| struct task_struct *t = p; |
| int count = 0; |
| |
| p->signal->group_stop_count = 0; |
| |
| while_each_thread(p, t) { |
| task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); |
| count++; |
| |
| /* Don't bother with already dead threads */ |
| if (t->exit_state) |
| continue; |
| sigaddset(&t->pending.signal, SIGKILL); |
| signal_wake_up(t, 1); |
| } |
| |
| return count; |
| } |
| |
| struct sighand_struct *__lock_task_sighand(struct task_struct *tsk, |
| unsigned long *flags) |
| { |
| struct sighand_struct *sighand; |
| |
| rcu_read_lock(); |
| for (;;) { |
| sighand = rcu_dereference(tsk->sighand); |
| if (unlikely(sighand == NULL)) |
| break; |
| |
| /* |
| * This sighand can be already freed and even reused, but |
| * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which |
| * initializes ->siglock: this slab can't go away, it has |
| * the same object type, ->siglock can't be reinitialized. |
| * |
| * We need to ensure that tsk->sighand is still the same |
| * after we take the lock, we can race with de_thread() or |
| * __exit_signal(). In the latter case the next iteration |
| * must see ->sighand == NULL. |
| */ |
| spin_lock_irqsave(&sighand->siglock, *flags); |
| if (likely(sighand == rcu_access_pointer(tsk->sighand))) |
| break; |
| spin_unlock_irqrestore(&sighand->siglock, *flags); |
| } |
| rcu_read_unlock(); |
| |
| return sighand; |
| } |
| |
| #ifdef CONFIG_LOCKDEP |
| void lockdep_assert_task_sighand_held(struct task_struct *task) |
| { |
| struct sighand_struct *sighand; |
| |
| rcu_read_lock(); |
| sighand = rcu_dereference(task->sighand); |
| if (sighand) |
| lockdep_assert_held(&sighand->siglock); |
| else |
| WARN_ON_ONCE(1); |
| rcu_read_unlock(); |
| } |
| #endif |
| |
| /* |
| * send signal info to all the members of a group |
| */ |
| int group_send_sig_info(int sig, struct kernel_siginfo *info, |
| struct task_struct *p, enum pid_type type) |
| { |
| int ret; |
| |
| rcu_read_lock(); |
| ret = check_kill_permission(sig, info, p); |
| rcu_read_unlock(); |
| |
| if (!ret && sig) { |
| ret = do_send_sig_info(sig, info, p, type); |
| if (!ret && sig == SIGKILL) { |
| bool reap = false; |
| |
| trace_android_vh_killed_process(current, p, &reap); |
| if (reap) |
| add_to_oom_reaper(p); |
| } |
| } |
| |
| return ret; |
| } |
| |
| /* |
| * __kill_pgrp_info() sends a signal to a process group: this is what the tty |
| * control characters do (^C, ^Z etc) |
| * - the caller must hold at least a readlock on tasklist_lock |
| */ |
| int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp) |
| { |
| struct task_struct *p = NULL; |
| int retval, success; |
| |
| success = 0; |
| retval = -ESRCH; |
| do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
| int err = group_send_sig_info(sig, info, p, PIDTYPE_PGID); |
| success |= !err; |
| retval = err; |
| } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
| return success ? 0 : retval; |
| } |
| |
| int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid) |
| { |
| int error = -ESRCH; |
| struct task_struct *p; |
| |
| for (;;) { |
| rcu_read_lock(); |
| p = pid_task(pid, PIDTYPE_PID); |
| if (p) |
| error = group_send_sig_info(sig, info, p, PIDTYPE_TGID); |
| rcu_read_unlock(); |
| if (likely(!p || error != -ESRCH)) |
| return error; |
| |
| /* |
| * The task was unhashed in between, try again. If it |
| * is dead, pid_task() will return NULL, if we race with |
| * de_thread() it will find the new leader. |
| */ |
| } |
| } |
| |
| static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid) |
| { |
| int error; |
| rcu_read_lock(); |
| error = kill_pid_info(sig, info, find_vpid(pid)); |
| rcu_read_unlock(); |
| return error; |
| } |
| |
| static inline bool kill_as_cred_perm(const struct cred *cred, |
| struct task_struct *target) |
| { |
| const struct cred *pcred = __task_cred(target); |
| |
| return uid_eq(cred->euid, pcred->suid) || |
| uid_eq(cred->euid, pcred->uid) || |
| uid_eq(cred->uid, pcred->suid) || |
| uid_eq(cred->uid, pcred->uid); |
| } |
| |
| /* |
| * The usb asyncio usage of siginfo is wrong. The glibc support |
| * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT. |
| * AKA after the generic fields: |
| * kernel_pid_t si_pid; |
| * kernel_uid32_t si_uid; |
| * sigval_t si_value; |
| * |
| * Unfortunately when usb generates SI_ASYNCIO it assumes the layout |
| * after the generic fields is: |
| * void __user *si_addr; |
| * |
| * This is a practical problem when there is a 64bit big endian kernel |
| * and a 32bit userspace. As the 32bit address will encoded in the low |
| * 32bits of the pointer. Those low 32bits will be stored at higher |
| * address than appear in a 32 bit pointer. So userspace will not |
| * see the address it was expecting for it's completions. |
| * |
| * There is nothing in the encoding that can allow |
| * copy_siginfo_to_user32 to detect this confusion of formats, so |
| * handle this by requiring the caller of kill_pid_usb_asyncio to |
| * notice when this situration takes place and to store the 32bit |
| * pointer in sival_int, instead of sival_addr of the sigval_t addr |
| * parameter. |
| */ |
| int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr, |
| struct pid *pid, const struct cred *cred) |
| { |
| struct kernel_siginfo info; |
| struct task_struct *p; |
| unsigned long flags; |
| int ret = -EINVAL; |
| |
| if (!valid_signal(sig)) |
| return ret; |
| |
| clear_siginfo(&info); |
| info.si_signo = sig; |
| info.si_errno = errno; |
| info.si_code = SI_ASYNCIO; |
| *((sigval_t *)&info.si_pid) = addr; |
| |
| rcu_read_lock(); |
| p = pid_task(pid, PIDTYPE_PID); |
| if (!p) { |
| ret = -ESRCH; |
| goto out_unlock; |
| } |
| if (!kill_as_cred_perm(cred, p)) { |
| ret = -EPERM; |
| goto out_unlock; |
| } |
| ret = security_task_kill(p, &info, sig, cred); |
| if (ret) |
| goto out_unlock; |
| |
| if (sig) { |
| if (lock_task_sighand(p, &flags)) { |
| ret = __send_signal_locked(sig, &info, p, PIDTYPE_TGID, false); |
| unlock_task_sighand(p, &flags); |
| } else |
| ret = -ESRCH; |
| } |
| out_unlock: |
| rcu_read_unlock(); |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio); |
| |
| /* |
| * kill_something_info() interprets pid in interesting ways just like kill(2). |
| * |
| * POSIX specifies that kill(-1,sig) is unspecified, but what we have |
| * is probably wrong. Should make it like BSD or SYSV. |
| */ |
| |
| static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid) |
| { |
| int ret; |
| |
| if (pid > 0) |
| return kill_proc_info(sig, info, pid); |
| |
| /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */ |
| if (pid == INT_MIN) |
| return -ESRCH; |
| |
| read_lock(&tasklist_lock); |
| if (pid != -1) { |
| ret = __kill_pgrp_info(sig, info, |
| pid ? find_vpid(-pid) : task_pgrp(current)); |
| } else { |
| int retval = 0, count = 0; |
| struct task_struct * p; |
| |
| for_each_process(p) { |
| if (task_pid_vnr(p) > 1 && |
| !same_thread_group(p, current)) { |
| int err = group_send_sig_info(sig, info, p, |
| PIDTYPE_MAX); |
| ++count; |
| if (err != -EPERM) |
| retval = err; |
| } |
| } |
| ret = count ? retval : -ESRCH; |
| } |
| read_unlock(&tasklist_lock); |
| |
| return ret; |
| } |
| |
| /* |
| * These are for backward compatibility with the rest of the kernel source. |
| */ |
| |
| int send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p) |
| { |
| /* |
| * Make sure legacy kernel users don't send in bad values |
| * (normal paths check this in check_kill_permission). |
| */ |
| if (!valid_signal(sig)) |
| return -EINVAL; |
| |
| return do_send_sig_info(sig, info, p, PIDTYPE_PID); |
| } |
| EXPORT_SYMBOL(send_sig_info); |
| |
| #define __si_special(priv) \ |
| ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO) |
| |
| int |
| send_sig(int sig, struct task_struct *p, int priv) |
| { |
| return send_sig_info(sig, __si_special(priv), p); |
| } |
| EXPORT_SYMBOL(send_sig); |
| |
| void force_sig(int sig) |
| { |
| struct kernel_siginfo info; |
| |
| clear_siginfo(&info); |
| info.si_signo = sig; |
| info.si_errno = 0; |
| info.si_code = SI_KERNEL; |
| info.si_pid = 0; |
| info.si_uid = 0; |
| force_sig_info(&info); |
| } |
| EXPORT_SYMBOL(force_sig); |
| |
| void force_fatal_sig(int sig) |
| { |
| struct kernel_siginfo info; |
| |
| clear_siginfo(&info); |
| info.si_signo = sig; |
| info.si_errno = 0; |
| info.si_code = SI_KERNEL; |
| info.si_pid = 0; |
| info.si_uid = 0; |
| force_sig_info_to_task(&info, current, HANDLER_SIG_DFL); |
| } |
| |
| void force_exit_sig(int sig) |
| { |
| struct kernel_siginfo info; |
| |
| clear_siginfo(&info); |
| info.si_signo = sig; |
| info.si_errno = 0; |
| info.si_code = SI_KERNEL; |
| info.si_pid = 0; |
| info.si_uid = 0; |
| force_sig_info_to_task(&info, current, HANDLER_EXIT); |
| } |
| |
| /* |
| * When things go south during signal handling, we |
| * will force a SIGSEGV. And if the signal that caused |
| * the problem was already a SIGSEGV, we'll want to |
| * make sure we don't even try to deliver the signal.. |
| */ |
| void force_sigsegv(int sig) |
| { |
| if (sig == SIGSEGV) |
| force_fatal_sig(SIGSEGV); |
| else |
| force_sig(SIGSEGV); |
| } |
| |
| int force_sig_fault_to_task(int sig, int code, void __user *addr |
| ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr) |
| , struct task_struct *t) |
| { |
| struct kernel_siginfo info; |
| |
| clear_siginfo(&info); |
| info.si_signo = sig; |
| info.si_errno = 0; |
| info.si_code = code; |
| info.si_addr = addr; |
| #ifdef __ia64__ |
| info.si_imm = imm; |
| info.si_flags = flags; |
| info.si_isr = isr; |
| #endif |
| return force_sig_info_to_task(&info, t, HANDLER_CURRENT); |
| } |
| |
| int force_sig_fault(int sig, int code, void __user *addr |
| ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)) |
| { |
| return force_sig_fault_to_task(sig, code, addr |
| ___ARCH_SI_IA64(imm, flags, isr), current); |
| } |
| |
| int send_sig_fault(int sig, int code, void __user *addr |
| ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr) |
| , struct task_struct *t) |
| { |
| struct kernel_siginfo info; |
| |
| clear_siginfo(&info); |
| info.si_signo = sig; |
| info.si_errno = 0; |
| info.si_code = code; |
| info.si_addr = addr; |
| #ifdef __ia64__ |
| info.si_imm = imm; |
| info.si_flags = flags; |
| info.si_isr = isr; |
| #endif |
| return send_sig_info(info.si_signo, &info, t); |
| } |
| |
| int force_sig_mceerr(int code, void __user *addr, short lsb) |
| { |
| struct kernel_siginfo info; |
| |
| WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR)); |
| clear_siginfo(&info); |
| info.si_signo = SIGBUS; |
| info.si_errno = 0; |
| info.si_code = code; |
| info.si_addr = addr; |
| info.si_addr_lsb = lsb; |
| return force_sig_info(&info); |
| } |
| |
| int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t) |
| { |
| struct kernel_siginfo info; |
| |
| WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR)); |
| clear_siginfo(&info); |
| info.si_signo = SIGBUS; |
| info.si_errno = 0; |
| info.si_code = code; |
| info.si_addr = addr; |
| info.si_addr_lsb = lsb; |
| return send_sig_info(info.si_signo, &info, t); |
| } |
| EXPORT_SYMBOL(send_sig_mceerr); |
| |
| int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper) |
| { |
| struct kernel_siginfo info; |
| |
| clear_siginfo(&info); |
| info.si_signo = SIGSEGV; |
| info.si_errno = 0; |
| info.si_code = SEGV_BNDERR; |
| info.si_addr = addr; |
| info.si_lower = lower; |
| info.si_upper = upper; |
| return force_sig_info(&info); |
| } |
| |
| #ifdef SEGV_PKUERR |
| int force_sig_pkuerr(void __user *addr, u32 pkey) |
| { |
| struct kernel_siginfo info; |
| |
| clear_siginfo(&info); |
| info.si_signo = SIGSEGV; |
| info.si_errno = 0; |
| info.si_code = SEGV_PKUERR; |
| info.si_addr = addr; |
| info.si_pkey = pkey; |
| return force_sig_info(&info); |
| } |
| #endif |
| |
| int send_sig_perf(void __user *addr, u32 type, u64 sig_data) |
| { |
| struct kernel_siginfo info; |
| |
| clear_siginfo(&info); |
| info.si_signo = SIGTRAP; |
| info.si_errno = 0; |
| info.si_code = TRAP_PERF; |
| info.si_addr = addr; |
| info.si_perf_data = sig_data; |
| info.si_perf_type = type; |
| |
| /* |
| * Signals generated by perf events should not terminate the whole |
| * process if SIGTRAP is blocked, however, delivering the signal |
| * asynchronously is better than not delivering at all. But tell user |
| * space if the signal was asynchronous, so it can clearly be |
| * distinguished from normal synchronous ones. |
| */ |
| info.si_perf_flags = sigismember(¤t->blocked, info.si_signo) ? |
| TRAP_PERF_FLAG_ASYNC : |
| 0; |
| |
| return send_sig_info(info.si_signo, &info, current); |
| } |
| |
| /** |
| * force_sig_seccomp - signals the task to allow in-process syscall emulation |
| * @syscall: syscall number to send to userland |
| * @reason: filter-supplied reason code to send to userland (via si_errno) |
| * @force_coredump: true to trigger a coredump |
| * |
| * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info. |
| */ |
| int force_sig_seccomp(int syscall, int reason, bool force_coredump) |
| { |
| struct kernel_siginfo info; |
| |
| clear_siginfo(&info); |
| info.si_signo = SIGSYS; |
| info.si_code = SYS_SECCOMP; |
| info.si_call_addr = (void __user *)KSTK_EIP(current); |
| info.si_errno = reason; |
| info.si_arch = syscall_get_arch(current); |
| info.si_syscall = syscall; |
| return force_sig_info_to_task(&info, current, |
| force_coredump ? HANDLER_EXIT : HANDLER_CURRENT); |
| } |
| |
| /* For the crazy architectures that include trap information in |
| * the errno field, instead of an actual errno value. |
| */ |
| int force_sig_ptrace_errno_trap(int errno, void __user *addr) |
| { |
| struct kernel_siginfo info; |
| |
| clear_siginfo(&info); |
| info.si_signo = SIGTRAP; |
| info.si_errno = errno; |
| info.si_code = TRAP_HWBKPT; |
| info.si_addr = addr; |
| return force_sig_info(&info); |
| } |
| |
| /* For the rare architectures that include trap information using |
| * si_trapno. |
| */ |
| int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno) |
| { |
| struct kernel_siginfo info; |
| |
| clear_siginfo(&info); |
| info.si_signo = sig; |
| info.si_errno = 0; |
| info.si_code = code; |
| info.si_addr = addr; |
| info.si_trapno = trapno; |
| return force_sig_info(&info); |
| } |
| |
| /* For the rare architectures that include trap information using |
| * si_trapno. |
| */ |
| int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno, |
| struct task_struct *t) |
| { |
| struct kernel_siginfo info; |
| |
| clear_siginfo(&info); |
| info.si_signo = sig; |
| info.si_errno = 0; |
| info.si_code = code; |
| info.si_addr = addr; |
| info.si_trapno = trapno; |
| return send_sig_info(info.si_signo, &info, t); |
| } |
| |
| int kill_pgrp(struct pid *pid, int sig, int priv) |
| { |
| int ret; |
| |
| read_lock(&tasklist_lock); |
| ret = __kill_pgrp_info(sig, __si_special(priv), pid); |
| read_unlock(&tasklist_lock); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL(kill_pgrp); |
| |
| int kill_pid(struct pid *pid, int sig, int priv) |
| { |
| return kill_pid_info(sig, __si_special(priv), pid); |
| } |
| EXPORT_SYMBOL(kill_pid); |
| |
| /* |
| * These functions support sending signals using preallocated sigqueue |
| * structures. This is needed "because realtime applications cannot |
| * afford to lose notifications of asynchronous events, like timer |
| * expirations or I/O completions". In the case of POSIX Timers |
| * we allocate the sigqueue structure from the timer_create. If this |
| * allocation fails we are able to report the failure to the application |
| * with an EAGAIN error. |
| */ |
| struct sigqueue *sigqueue_alloc(void) |
| { |
| return __sigqueue_alloc(-1, current, GFP_KERNEL, 0, SIGQUEUE_PREALLOC); |
| } |
| |
| void sigqueue_free(struct sigqueue *q) |
| { |
| unsigned long flags; |
| spinlock_t *lock = ¤t->sighand->siglock; |
| |
| BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); |
| /* |
| * We must hold ->siglock while testing q->list |
| * to serialize with collect_signal() or with |
| * __exit_signal()->flush_sigqueue(). |
| */ |
| spin_lock_irqsave(lock, flags); |
| q->flags &= ~SIGQUEUE_PREALLOC; |
| /* |
| * If it is queued it will be freed when dequeued, |
| * like the "regular" sigqueue. |
| */ |
| if (!list_empty(&q->list)) |
| q = NULL; |
| spin_unlock_irqrestore(lock, flags); |
| |
| if (q) |
| __sigqueue_free(q); |
| } |
| |
| int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type) |
| { |
| int sig = q->info.si_signo; |
| struct sigpending *pending; |
| struct task_struct *t; |
| unsigned long flags; |
| int ret, result; |
| |
| BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); |
| |
| ret = -1; |
| rcu_read_lock(); |
| t = pid_task(pid, type); |
| if (!t || !likely(lock_task_sighand(t, &flags))) |
| goto ret; |
| |
| ret = 1; /* the signal is ignored */ |
| result = TRACE_SIGNAL_IGNORED; |
| if (!prepare_signal(sig, t, false)) |
| goto out; |
| |
| ret = 0; |
| if (unlikely(!list_empty(&q->list))) { |
| /* |
| * If an SI_TIMER entry is already queue just increment |
| * the overrun count. |
| */ |
| BUG_ON(q->info.si_code != SI_TIMER); |
| q->info.si_overrun++; |
| result = TRACE_SIGNAL_ALREADY_PENDING; |
| goto out; |
| } |
| q->info.si_overrun = 0; |
| |
| signalfd_notify(t, sig); |
| pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending; |
| list_add_tail(&q->list, &pending->list); |
| sigaddset(&pending->signal, sig); |
| complete_signal(sig, t, type); |
| result = TRACE_SIGNAL_DELIVERED; |
| out: |
| trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result); |
| unlock_task_sighand(t, &flags); |
| ret: |
| rcu_read_unlock(); |
| return ret; |
| } |
| |
| static void do_notify_pidfd(struct task_struct *task) |
| { |
| struct pid *pid; |
| |
| WARN_ON(task->exit_state == 0); |
| pid = task_pid(task); |
| wake_up_all(&pid->wait_pidfd); |
| } |
| |
| /* |
| * Let a parent know about the death of a child. |
| * For a stopped/continued status change, use do_notify_parent_cldstop instead. |
| * |
| * Returns true if our parent ignored us and so we've switched to |
| * self-reaping. |
| */ |
| bool do_notify_parent(struct task_struct *tsk, int sig) |
| { |
| struct kernel_siginfo info; |
| unsigned long flags; |
| struct sighand_struct *psig; |
| bool autoreap = false; |
| u64 utime, stime; |
| |
| WARN_ON_ONCE(sig == -1); |
| |
| /* do_notify_parent_cldstop should have been called instead. */ |
| WARN_ON_ONCE(task_is_stopped_or_traced(tsk)); |
| |
| WARN_ON_ONCE(!tsk->ptrace && |
| (tsk->group_leader != tsk || !thread_group_empty(tsk))); |
| |
| /* Wake up all pidfd waiters */ |
| do_notify_pidfd(tsk); |
| |
| if (sig != SIGCHLD) { |
| /* |
| * This is only possible if parent == real_parent. |
| * Check if it has changed security domain. |
| */ |
| if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id)) |
| sig = SIGCHLD; |
| } |
| |
| clear_siginfo(&info); |
| info.si_signo = sig; |
| info.si_errno = 0; |
| /* |
| * We are under tasklist_lock here so our parent is tied to |
| * us and cannot change. |
| * |
| * task_active_pid_ns will always return the same pid namespace |
| * until a task passes through release_task. |
| * |
| * write_lock() currently calls preempt_disable() which is the |
| * same as rcu_read_lock(), but according to Oleg, this is not |
| * correct to rely on this |
| */ |
| rcu_read_lock(); |
| info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent)); |
| info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns), |
| task_uid(tsk)); |
| rcu_read_unlock(); |
| |
| task_cputime(tsk, &utime, &stime); |
| info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime); |
| info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime); |
| |
| info.si_status = tsk->exit_code & 0x7f; |
| if (tsk->exit_code & 0x80) |
| info.si_code = CLD_DUMPED; |
| else if (tsk->exit_code & 0x7f) |
| info.si_code = CLD_KILLED; |
| else { |
| info.si_code = CLD_EXITED; |
| info.si_status = tsk->exit_code >> 8; |
| } |
| |
| psig = tsk->parent->sighand; |
| spin_lock_irqsave(&psig->siglock, flags); |
| if (!tsk->ptrace && sig == SIGCHLD && |
| (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN || |
| (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) { |
| /* |
| * We are exiting and our parent doesn't care. POSIX.1 |
| * defines special semantics for setting SIGCHLD to SIG_IGN |
| * or setting the SA_NOCLDWAIT flag: we should be reaped |
| * automatically and not left for our parent's wait4 call. |
| * Rather than having the parent do it as a magic kind of |
| * signal handler, we just set this to tell do_exit that we |
| * can be cleaned up without becoming a zombie. Note that |
| * we still call __wake_up_parent in this case, because a |
| * blocked sys_wait4 might now return -ECHILD. |
| * |
| * Whether we send SIGCHLD or not for SA_NOCLDWAIT |
| * is implementation-defined: we do (if you don't want |
| * it, just use SIG_IGN instead). |
| */ |
| autoreap = true; |
| if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) |
| sig = 0; |
| } |
| /* |
| * Send with __send_signal as si_pid and si_uid are in the |
| * parent's namespaces. |
| */ |
| if (valid_signal(sig) && sig) |
| __send_signal_locked(sig, &info, tsk->parent, PIDTYPE_TGID, false); |
| __wake_up_parent(tsk, tsk->parent); |
| spin_unlock_irqrestore(&psig->siglock, flags); |
| |
| return autoreap; |
| } |
| |
| /** |
| * do_notify_parent_cldstop - notify parent of stopped/continued state change |
| * @tsk: task reporting the state change |
| * @for_ptracer: the notification is for ptracer |
| * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report |
| * |
| * Notify @tsk's parent that the stopped/continued state has changed. If |
| * @for_ptracer is %false, @tsk's group leader notifies to its real parent. |
| * If %true, @tsk reports to @tsk->parent which should be the ptracer. |
| * |
| * CONTEXT: |
| * Must be called with tasklist_lock at least read locked. |
| */ |
| static void do_notify_parent_cldstop(struct task_struct *tsk, |
| bool for_ptracer, int why) |
| { |
| struct kernel_siginfo info; |
| unsigned long flags; |
| struct task_struct *parent; |
| struct sighand_struct *sighand; |
| u64 utime, stime; |
| |
| if (for_ptracer) { |
| parent = tsk->parent; |
| } else { |
| tsk = tsk->group_leader; |
| parent = tsk->real_parent; |
| } |
| |
| clear_siginfo(&info); |
| info.si_signo = SIGCHLD; |
| info.si_errno = 0; |
| /* |
| * see comment in do_notify_parent() about the following 4 lines |
| */ |
| rcu_read_lock(); |
| info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent)); |
| info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk)); |
| rcu_read_unlock(); |
| |
| task_cputime(tsk, &utime, &stime); |
| info.si_utime = nsec_to_clock_t(utime); |
| info.si_stime = nsec_to_clock_t(stime); |
| |
| info.si_code = why; |
| switch (why) { |
| case CLD_CONTINUED: |
| info.si_status = SIGCONT; |
| break; |
| case CLD_STOPPED: |
| info.si_status = tsk->signal->group_exit_code & 0x7f; |
| break; |
| case CLD_TRAPPED: |
| info.si_status = tsk->exit_code & 0x7f; |
| break; |
| default: |
| BUG(); |
| } |
| |
| sighand = parent->sighand; |
| spin_lock_irqsave(&sighand->siglock, flags); |
| if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN && |
| !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP)) |
| send_signal_locked(SIGCHLD, &info, parent, PIDTYPE_TGID); |
| /* |
| * Even if SIGCHLD is not generated, we must wake up wait4 calls. |
| */ |
| __wake_up_parent(tsk, parent); |
| spin_unlock_irqrestore(&sighand->siglock, flags); |
| } |
| |
| /* |
| * This must be called with current->sighand->siglock held. |
| * |
| * This should be the path for all ptrace stops. |
| * We always set current->last_siginfo while stopped here. |
| * That makes it a way to test a stopped process for |
| * being ptrace-stopped vs being job-control-stopped. |
| * |
| * Returns the signal the ptracer requested the code resume |
| * with. If the code did not stop because the tracer is gone, |
| * the stop signal remains unchanged unless clear_code. |
| */ |
| static int ptrace_stop(int exit_code, int why, unsigned long message, |
| kernel_siginfo_t *info) |
| __releases(¤t->sighand->siglock) |
| __acquires(¤t->sighand->siglock) |
| { |
| bool gstop_done = false; |
| |
| if (arch_ptrace_stop_needed()) { |
| /* |
| * The arch code has something special to do before a |
| * ptrace stop. This is allowed to block, e.g. for faults |
| * on user stack pages. We can't keep the siglock while |
| * calling arch_ptrace_stop, so we must release it now. |
| * To preserve proper semantics, we must do this before |
| * any signal bookkeeping like checking group_stop_count. |
| */ |
| spin_unlock_irq(¤t->sighand->siglock); |
| arch_ptrace_stop(); |
| spin_lock_irq(¤t->sighand->siglock); |
| } |
| |
| /* |
| * After this point ptrace_signal_wake_up or signal_wake_up |
| * will clear TASK_TRACED if ptrace_unlink happens or a fatal |
| * signal comes in. Handle previous ptrace_unlinks and fatal |
| * signals here to prevent ptrace_stop sleeping in schedule. |
| */ |
| if (!current->ptrace || __fatal_signal_pending(current)) |
| return exit_code; |
| |
| set_special_state(TASK_TRACED); |
| current->jobctl |= JOBCTL_TRACED; |
| |
| /* |
| * We're committing to trapping. TRACED should be visible before |
| * TRAPPING is cleared; otherwise, the tracer might fail do_wait(). |
| * Also, transition to TRACED and updates to ->jobctl should be |
| * atomic with respect to siglock and should be done after the arch |
| * hook as siglock is released and regrabbed across it. |
| * |
| * TRACER TRACEE |
| * |
| * ptrace_attach() |
| * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED) |
| * do_wait() |
| * set_current_state() smp_wmb(); |
| * ptrace_do_wait() |
| * wait_task_stopped() |
| * task_stopped_code() |
| * [L] task_is_traced() [S] task_clear_jobctl_trapping(); |
| */ |
| smp_wmb(); |
| |
| current->ptrace_message = message; |
| current->last_siginfo = info; |
| current->exit_code = exit_code; |
| |
| /* |
| * If @why is CLD_STOPPED, we're trapping to participate in a group |
| * stop. Do the bookkeeping. Note that if SIGCONT was delievered |
| * across siglock relocks since INTERRUPT was scheduled, PENDING |
| * could be clear now. We act as if SIGCONT is received after |
| * TASK_TRACED is entered - ignore it. |
| */ |
| if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING)) |
| gstop_done = task_participate_group_stop(current); |
| |
| /* any trap clears pending STOP trap, STOP trap clears NOTIFY */ |
| task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP); |
| if (info && info->si_code >> 8 == PTRACE_EVENT_STOP) |
| task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY); |
| |
| /* entering a trap, clear TRAPPING */ |
| task_clear_jobctl_trapping(current); |
| |
| spin_unlock_irq(¤t->sighand->siglock); |
| read_lock(&tasklist_lock); |
| /* |
| * Notify parents of the stop. |
| * |
| * While ptraced, there are two parents - the ptracer and |
| * the real_parent of the group_leader. The ptracer should |
| * know about every stop while the real parent is only |
| * interested in the completion of group stop. The states |
| * for the two don't interact with each other. Notify |
| * separately unless they're gonna be duplicates. |
| */ |
| if (current->ptrace) |
| do_notify_parent_cldstop(current, true, why); |
| if (gstop_done && (!current->ptrace || ptrace_reparented(current))) |
| do_notify_parent_cldstop(current, false, why); |
| |
| /* |
| * Don't want to allow preemption here, because |
| * sys_ptrace() needs this task to be inactive. |
| * |
| * XXX: implement read_unlock_no_resched(). |
| */ |
| preempt_disable(); |
| read_unlock(&tasklist_lock); |
| cgroup_enter_frozen(); |
| preempt_enable_no_resched(); |
| schedule(); |
| cgroup_leave_frozen(true); |
| |
| /* |
| * We are back. Now reacquire the siglock before touching |
| * last_siginfo, so that we are sure to have synchronized with |
| * any signal-sending on another CPU that wants to examine it. |
| */ |
| spin_lock_irq(¤t->sighand->siglock); |
| exit_code = current->exit_code; |
| current->last_siginfo = NULL; |
| current->ptrace_message = 0; |
| current->exit_code = 0; |
| |
| /* LISTENING can be set only during STOP traps, clear it */ |
| current->jobctl &= ~(JOBCTL_LISTENING | JOBCTL_PTRACE_FROZEN); |
| |
| /* |
| * Queued signals ignored us while we were stopped for tracing. |
| * So check for any that we should take before resuming user mode. |
| * This sets TIF_SIGPENDING, but never clears it. |
| */ |
| recalc_sigpending_tsk(current); |
| return exit_code; |
| } |
| |
| static int ptrace_do_notify(int signr, int exit_code, int why, unsigned long message) |
| { |
| kernel_siginfo_t info; |
| |
| clear_siginfo(&info); |
| info.si_signo = signr; |
| info.si_code = exit_code; |
| info.si_pid = task_pid_vnr(current); |
| info.si_uid = from_kuid_munged(current_user_ns(), current_uid()); |
| |
| /* Let the debugger run. */ |
| return ptrace_stop(exit_code, why, message, &info); |
| } |
| |
| int ptrace_notify(int exit_code, unsigned long message) |
| { |
| int signr; |
| |
| BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP); |
| if (unlikely(task_work_pending(current))) |
| task_work_run(); |
| |
| spin_lock_irq(¤t->sighand->siglock); |
| signr = ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED, message); |
| spin_unlock_irq(¤t->sighand->siglock); |
| return signr; |
| } |
| |
| /** |
| * do_signal_stop - handle group stop for SIGSTOP and other stop signals |
| * @signr: signr causing group stop if initiating |
| * |
| * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr |
| * and participate in it. If already set, participate in the existing |
| * group stop. If participated in a group stop (and thus slept), %true is |
| * returned with siglock released. |
| * |
| * If ptraced, this function doesn't handle stop itself. Instead, |
| * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock |
| * untouched. The caller must ensure that INTERRUPT trap handling takes |
| * places afterwards. |
| * |
| * CONTEXT: |
| * Must be called with @current->sighand->siglock held, which is released |
| * on %true return. |
| * |
| * RETURNS: |
| * %false if group stop is already cancelled or ptrace trap is scheduled. |
| * %true if participated in group stop. |
| */ |
| static bool do_signal_stop(int signr) |
| __releases(¤t->sighand->siglock) |
| { |
| struct signal_struct *sig = current->signal; |
| |
| if (!(current->jobctl & JOBCTL_STOP_PENDING)) { |
| unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME; |
| struct task_struct *t; |
| |
| /* signr will be recorded in task->jobctl for retries */ |
| WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK); |
| |
| if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) || |
| unlikely(sig->flags & SIGNAL_GROUP_EXIT) || |
| unlikely(sig->group_exec_task)) |
| return false; |
| /* |
| * There is no group stop already in progress. We must |
| * initiate one now. |
| * |
| * While ptraced, a task may be resumed while group stop is |
| * still in effect and then receive a stop signal and |
| * initiate another group stop. This deviates from the |
| * usual behavior as two consecutive stop signals can't |
| * cause two group stops when !ptraced. That is why we |
| * also check !task_is_stopped(t) below. |
| * |
| * The condition can be distinguished by testing whether |
| * SIGNAL_STOP_STOPPED is already set. Don't generate |
| * group_exit_code in such case. |
| * |
| * This is not necessary for SIGNAL_STOP_CONTINUED because |
| * an intervening stop signal is required to cause two |
| * continued events regardless of ptrace. |
| */ |
| if (!(sig->flags & SIGNAL_STOP_STOPPED)) |
| sig->group_exit_code = signr; |
| |
| sig->group_stop_count = 0; |
| |
| if (task_set_jobctl_pending(current, signr | gstop)) |
| sig->group_stop_count++; |
| |
| t = current; |
| while_each_thread(current, t) { |
| /* |
| * Setting state to TASK_STOPPED for a group |
| * stop is always done with the siglock held, |
| * so this check has no races. |
| */ |
| if (!task_is_stopped(t) && |
| task_set_jobctl_pending(t, signr | gstop)) { |
| sig->group_stop_count++; |
| if (likely(!(t->ptrace & PT_SEIZED))) |
| signal_wake_up(t, 0); |
| else |
| ptrace_trap_notify(t); |
| } |
| } |
| } |
| |
| if (likely(!current->ptrace)) { |
| int notify = 0; |
| |
| /* |
| * If there are no other threads in the group, or if there |
| * is a group stop in progress and we are the last to stop, |
| * report to the parent. |
| */ |
| if (task_participate_group_stop(current)) |
| notify = CLD_STOPPED; |
| |
| current->jobctl |= JOBCTL_STOPPED; |
| set_special_state(TASK_STOPPED); |
| spin_unlock_irq(¤t->sighand->siglock); |
| |
| /* |
| * Notify the parent of the group stop completion. Because |
| * we're not holding either the siglock or tasklist_lock |
| * here, ptracer may attach inbetween; however, this is for |
| * group stop and should always be delivered to the real |
| * parent of the group leader. The new ptracer will get |
| * its notification when this task transitions into |
| * TASK_TRACED. |
| */ |
| if (notify) { |
| read_lock(&tasklist_lock); |
| do_notify_parent_cldstop(current, false, notify); |
| read_unlock(&tasklist_lock); |
| } |
| |
| /* Now we don't run again until woken by SIGCONT or SIGKILL */ |
| cgroup_enter_frozen(); |
| schedule(); |
| return true; |
| } else { |
| /* |
| * While ptraced, group stop is handled by STOP trap. |
| * Schedule it and let the caller deal with it. |
| */ |
| task_set_jobctl_pending(current, JOBCTL_TRAP_STOP); |
| return false; |
| } |
| } |
| |
| /** |
| * do_jobctl_trap - take care of ptrace jobctl traps |
| * |
| * When PT_SEIZED, it's used for both group stop and explicit |
| * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with |
| * accompanying siginfo. If stopped, lower eight bits of exit_code contain |
| * the stop signal; otherwise, %SIGTRAP. |
| * |
| * When !PT_SEIZED, it's used only for group stop trap with stop signal |
| * number as exit_code and no siginfo. |
| * |
| * CONTEXT: |
| * Must be called with @current->sighand->siglock held, which may be |
| * released and re-acquired before returning with intervening sleep. |
| */ |
| static void do_jobctl_trap(void) |
| { |
| struct signal_struct *signal = current->signal; |
| int signr = current->jobctl & JOBCTL_STOP_SIGMASK; |
| |
| if (current->ptrace & PT_SEIZED) { |
| if (!signal->group_stop_count && |
| !(signal->flags & SIGNAL_STOP_STOPPED)) |
| signr = SIGTRAP; |
| WARN_ON_ONCE(!signr); |
| ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8), |
| CLD_STOPPED, 0); |
| } else { |
| WARN_ON_ONCE(!signr); |
| ptrace_stop(signr, CLD_STOPPED, 0, NULL); |
| } |
| } |
| |
| /** |
| * do_freezer_trap - handle the freezer jobctl trap |
| * |
| * Puts the task into frozen state, if only the task is not about to quit. |
| * In this case it drops JOBCTL_TRAP_FREEZE. |
| * |
| * CONTEXT: |
| * Must be called with @current->sighand->siglock held, |
| * which is always released before returning. |
| */ |
| static void do_freezer_trap(void) |
| __releases(¤t->sighand->siglock) |
| { |
| /* |
| * If there are other trap bits pending except JOBCTL_TRAP_FREEZE, |
| * let's make another loop to give it a chance to be handled. |
| * In any case, we'll return back. |
| */ |
| if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) != |
| JOBCTL_TRAP_FREEZE) { |
| spin_unlock_irq(¤t->sighand->siglock); |
| return; |
| } |
| |
| /* |
| * Now we're sure that there is no pending fatal signal and no |
| * pending traps. Clear TIF_SIGPENDING to not get out of schedule() |
| * immediately (if there is a non-fatal signal pending), and |
| * put the task into sleep. |
| */ |
| __set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE); |
| clear_thread_flag(TIF_SIGPENDING); |
| spin_unlock_irq(¤t->sighand->siglock); |
| cgroup_enter_frozen(); |
| schedule(); |
| } |
| |
| static int ptrace_signal(int signr, kernel_siginfo_t *info, enum pid_type type) |
| { |
| /* |
| * We do not check sig_kernel_stop(signr) but set this marker |
| * unconditionally because we do not know whether debugger will |
| * change signr. This flag has no meaning unless we are going |
| * to stop after return from ptrace_stop(). In this case it will |
| * be checked in do_signal_stop(), we should only stop if it was |
| * not cleared by SIGCONT while we were sleeping. See also the |
| * comment in dequeue_signal(). |
| */ |
| current->jobctl |= JOBCTL_STOP_DEQUEUED; |
| signr = ptrace_stop(signr, CLD_TRAPPED, 0, info); |
| |
| /* We're back. Did the debugger cancel the sig? */ |
| if (signr == 0) |
| return signr; |
| |
| /* |
| * Update the siginfo structure if the signal has |
| * changed. If the debugger wanted something |
| * specific in the siginfo structure then it should |
| * have updated *info via PTRACE_SETSIGINFO. |
| */ |
| if (signr != info->si_signo) { |
| clear_siginfo(info); |
| info->si_signo = signr; |
| info->si_errno = 0; |
| info->si_code = SI_USER; |
| rcu_read_lock(); |
| info->si_pid = task_pid_vnr(current->parent); |
| info->si_uid = from_kuid_munged(current_user_ns(), |
| task_uid(current->parent)); |
| rcu_read_unlock(); |
| } |
| |
| /* If the (new) signal is now blocked, requeue it. */ |
| if (sigismember(¤t->blocked, signr) || |
| fatal_signal_pending(current)) { |
| send_signal_locked(signr, info, current, type); |
| signr = 0; |
| } |
| |
| return signr; |
| } |
| |
| static void hide_si_addr_tag_bits(struct ksignal *ksig) |
| { |
| switch (siginfo_layout(ksig->sig, ksig->info.si_code)) { |
| case SIL_FAULT: |
| case SIL_FAULT_TRAPNO: |
| case SIL_FAULT_MCEERR: |
| case SIL_FAULT_BNDERR: |
| case SIL_FAULT_PKUERR: |
| case SIL_FAULT_PERF_EVENT: |
| ksig->info.si_addr = arch_untagged_si_addr( |
| ksig->info.si_addr, ksig->sig, ksig->info.si_code); |
| break; |
| case SIL_KILL: |
| case SIL_TIMER: |
| case SIL_POLL: |
| case SIL_CHLD: |
| case SIL_RT: |
| case SIL_SYS: |
| break; |
| } |
| } |
| |
| bool get_signal(struct ksignal *ksig) |
| { |
| struct sighand_struct *sighand = current->sighand; |
| struct signal_struct *signal = current->signal; |
| int signr; |
| |
| clear_notify_signal(); |
| if (unlikely(task_work_pending(current))) |
| task_work_run(); |
| |
| if (!task_sigpending(current)) |
| return false; |
| |
| if (unlikely(uprobe_deny_signal())) |
| return false; |
| |
| /* |
| * Do this once, we can't return to user-mode if freezing() == T. |
| * do_signal_stop() and ptrace_stop() do freezable_schedule() and |
| * thus do not need another check after return. |
| */ |
| try_to_freeze(); |
| |
| relock: |
| spin_lock_irq(&sighand->siglock); |
| |
| /* |
| * Every stopped thread goes here after wakeup. Check to see if |
| * we should notify the parent, prepare_signal(SIGCONT) encodes |
| * the CLD_ si_code into SIGNAL_CLD_MASK bits. |
| */ |
| if (unlikely(signal->flags & SIGNAL_CLD_MASK)) { |
| int why; |
| |
| if (signal->flags & SIGNAL_CLD_CONTINUED) |
| why = CLD_CONTINUED; |
| else |
| why = CLD_STOPPED; |
| |
| signal->flags &= ~SIGNAL_CLD_MASK; |
| |
| spin_unlock_irq(&sighand->siglock); |
| |
| /* |
| * Notify the parent that we're continuing. This event is |
| * always per-process and doesn't make whole lot of sense |
| * for ptracers, who shouldn't consume the state via |
| * wait(2) either, but, for backward compatibility, notify |
| * the ptracer of the group leader too unless it's gonna be |
| * a duplicate. |
| */ |
| read_lock(&tasklist_lock); |
| do_notify_parent_cldstop(current, false, why); |
| |
| if (ptrace_reparented(current->group_leader)) |
| do_notify_parent_cldstop(current->group_leader, |
| true, why); |
| read_unlock(&tasklist_lock); |
| |
| goto relock; |
| } |
| |
| for (;;) { |
| struct k_sigaction *ka; |
| enum pid_type type; |
| |
| /* Has this task already been marked for death? */ |
| if ((signal->flags & SIGNAL_GROUP_EXIT) || |
| signal->group_exec_task) { |
| ksig->info.si_signo = signr = SIGKILL; |
| sigdelset(¤t->pending.signal, SIGKILL); |
| trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO, |
| &sighand->action[SIGKILL - 1]); |
| recalc_sigpending(); |
| goto fatal; |
| } |
| |
| if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) && |
| do_signal_stop(0)) |
| goto relock; |
| |
| if (unlikely(current->jobctl & |
| (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) { |
| if (current->jobctl & JOBCTL_TRAP_MASK) { |
| do_jobctl_trap(); |
| spin_unlock_irq(&sighand->siglock); |
| } else if (current->jobctl & JOBCTL_TRAP_FREEZE) |
| do_freezer_trap(); |
| |
| goto relock; |
| } |
| |
| /* |
| * If the task is leaving the frozen state, let's update |
| * cgroup counters and reset the frozen bit. |
| */ |
| if (unlikely(cgroup_task_frozen(current))) { |
| spin_unlock_irq(&sighand->siglock); |
| cgroup_leave_frozen(false); |
| goto relock; |
| } |
| |
| /* |
| * Signals generated by the execution of an instruction |
| * need to be delivered before any other pending signals |
| * so that the instruction pointer in the signal stack |
| * frame points to the faulting instruction. |
| */ |
| type = PIDTYPE_PID; |
| signr = dequeue_synchronous_signal(&ksig->info); |
| if (!signr) |
| signr = dequeue_signal(current, ¤t->blocked, |
| &ksig->info, &type); |
| |
| if (!signr) |
| break; /* will return 0 */ |
| |
| if (unlikely(current->ptrace) && (signr != SIGKILL) && |
| !(sighand->action[signr -1].sa.sa_flags & SA_IMMUTABLE)) { |
| signr = ptrace_signal(signr, &ksig->info, type); |
| if (!signr) |
| continue; |
| } |
| |
| ka = &sighand->action[signr-1]; |
| |
| /* Trace actually delivered signals. */ |
| trace_signal_deliver(signr, &ksig->info, ka); |
| |
| if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */ |
| continue; |
| if (ka->sa.sa_handler != SIG_DFL) { |
| /* Run the handler. */ |
| ksig->ka = *ka; |
| |
| if (ka->sa.sa_flags & SA_ONESHOT) |
| ka->sa.sa_handler = SIG_DFL; |
| |
| break; /* will return non-zero "signr" value */ |
| } |
| |
| /* |
| * Now we are doing the default action for this signal. |
| */ |
| if (sig_kernel_ignore(signr)) /* Default is nothing. */ |
| continue; |
| |
| /* |
| * Global init gets no signals it doesn't want. |
| * Container-init gets no signals it doesn't want from same |
| * container. |
| * |
| * Note that if global/container-init sees a sig_kernel_only() |
| * signal here, the signal must have been generated internally |
| * or must have come from an ancestor namespace. In either |
| * case, the signal cannot be dropped. |
| */ |
| if (unlikely(signal->flags & SIGNAL_UNKILLABLE) && |
| !sig_kernel_only(signr)) |
| continue; |
| |
| if (sig_kernel_stop(signr)) { |
| /* |
| * The default action is to stop all threads in |
| * the thread group. The job control signals |
| * do nothing in an orphaned pgrp, but SIGSTOP |
| * always works. Note that siglock needs to be |
| * dropped during the call to is_orphaned_pgrp() |
| * because of lock ordering with tasklist_lock. |
| * This allows an intervening SIGCONT to be posted. |
| * We need to check for that and bail out if necessary. |
| */ |
| if (signr != SIGSTOP) { |
| spin_unlock_irq(&sighand->siglock); |
| |
| /* signals can be posted during this window */ |
| |
| if (is_current_pgrp_orphaned()) |
| goto relock; |
| |
| spin_lock_irq(&sighand->siglock); |
| } |
| |
| if (likely(do_signal_stop(ksig->info.si_signo))) { |
| /* It released the siglock. */ |
| goto relock; |
| } |
| |
| /* |
| * We didn't actually stop, due to a race |
| * with SIGCONT or something like that. |
| */ |
| continue; |
| } |
| |
| fatal: |
| spin_unlock_irq(&sighand->siglock); |
| if (unlikely(cgroup_task_frozen(current))) |
| cgroup_leave_frozen(true); |
| |
| /* |
| * Anything else is fatal, maybe with a core dump. |
| */ |
| current->flags |= PF_SIGNALED; |
| |
| if (sig_kernel_coredump(signr)) { |
| if (print_fatal_signals) |
| print_fatal_signal(ksig->info.si_signo); |
| proc_coredump_connector(current); |
| /* |
| * If it was able to dump core, this kills all |
| * other threads in the group and synchronizes with |
| * their demise. If we lost the race with another |
| * thread getting here, it set group_exit_code |
| * first and our do_group_exit call below will use |
| * that value and ignore the one we pass it. |
| */ |
| do_coredump(&ksig->info); |
| } |
| |
| /* |
| * PF_IO_WORKER threads will catch and exit on fatal signals |
| * themselves. They have cleanup that must be performed, so |
| * we cannot call do_exit() on their behalf. |
| */ |
| if (current->flags & PF_IO_WORKER) |
| goto out; |
| |
| /* |
| * Death signals, no core dump. |
| */ |
| do_group_exit(ksig->info.si_signo); |
| /* NOTREACHED */ |
| } |
| spin_unlock_irq(&sighand->siglock); |
| out: |
| ksig->sig = signr; |
| |
| if (!(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS)) |
| hide_si_addr_tag_bits(ksig); |
| |
| return ksig->sig > 0; |
| } |
| |
| /** |
| * signal_delivered - called after signal delivery to update blocked signals |
| * @ksig: kernel signal struct |
| * @stepping: nonzero if debugger single-step or block-step in use |
| * |
| * This function should be called when a signal has successfully been |
| * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask |
| * is always blocked), and the signal itself is blocked unless %SA_NODEFER |
| * is set in @ksig->ka.sa.sa_flags. Tracing is notified. |
| */ |
| static void signal_delivered(struct ksignal *ksig, int stepping) |
| { |
| sigset_t blocked; |
| |
| /* A signal was successfully delivered, and the |
| saved sigmask was stored on the signal frame, |
| and will be restored by sigreturn. So we can |
| simply clear the restore sigmask flag. */ |
| clear_restore_sigmask(); |
| |
| sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask); |
| if (!(ksig->ka.sa.sa_flags & SA_NODEFER)) |
| sigaddset(&blocked, ksig->sig); |
| set_current_blocked(&blocked); |
| if (current->sas_ss_flags & SS_AUTODISARM) |
| sas_ss_reset(current); |
| if (stepping) |
| ptrace_notify(SIGTRAP, 0); |
| } |
| |
| void signal_setup_done(int failed, struct ksignal *ksig, int stepping) |
| { |
| if (failed) |
| force_sigsegv(ksig->sig); |
| else |
| signal_delivered(ksig, stepping); |
| } |
| |
| /* |
| * It could be that complete_signal() picked us to notify about the |
| * group-wide signal. Other threads should be notified now to take |
| * the shared signals in @which since we will not. |
| */ |
| static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which) |
| { |
| sigset_t retarget; |
| struct task_struct *t; |
| |
| sigandsets(&retarget, &tsk->signal->shared_pending.signal, which); |
| if (sigisemptyset(&retarget)) |
| return; |
| |
| t = tsk; |
| while_each_thread(tsk, t) { |
| if (t->flags & PF_EXITING) |
| continue; |
| |
| if (!has_pending_signals(&retarget, &t->blocked)) |
| continue; |
| /* Remove the signals this thread can handle. */ |
| sigandsets(&retarget, &retarget, &t->blocked); |
| |
| if (!task_sigpending(t)) |
| signal_wake_up(t, 0); |
| |
| if (sigisemptyset(&retarget)) |
| break; |
| } |
| } |
| |
| void exit_signals(struct task_struct *tsk) |
| { |
| int group_stop = 0; |
| sigset_t unblocked; |
| |
| /* |
| * @tsk is about to have PF_EXITING set - lock out users which |
| * expect stable threadgroup. |
| */ |
| cgroup_threadgroup_change_begin(tsk); |
| |
| if (thread_group_empty(tsk) || (tsk->signal->flags & SIGNAL_GROUP_EXIT)) { |
| tsk->flags |= PF_EXITING; |
| cgroup_threadgroup_change_end(tsk); |
| return; |
| } |
| |
| spin_lock_irq(&tsk->sighand->siglock); |
| /* |
| * From now this task is not visible for group-wide signals, |
| * see wants_signal(), do_signal_stop(). |
| */ |
| tsk->flags |= PF_EXITING; |
| |
| cgroup_threadgroup_change_end(tsk); |
| |
| if (!task_sigpending(tsk)) |
| goto out; |
| |
| unblocked = tsk->blocked; |
| signotset(&unblocked); |
| retarget_shared_pending(tsk, &unblocked); |
| |
| if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) && |
| task_participate_group_stop(tsk)) |
| group_stop = CLD_STOPPED; |
| out: |
| spin_unlock_irq(&tsk->sighand->siglock); |
| |
| /* |
| * If group stop has completed, deliver the notification. This |
| * should always go to the real parent of the group leader. |
| */ |
| if (unlikely(group_stop)) { |
| read_lock(&tasklist_lock); |
| do_notify_parent_cldstop(tsk, false, group_stop); |
| read_unlock(&tasklist_lock); |
| } |
| } |
| |
| /* |
| * System call entry points. |
| */ |
| |
| /** |
| * sys_restart_syscall - restart a system call |
| */ |
| SYSCALL_DEFINE0(restart_syscall) |
| { |
| struct restart_block *restart = ¤t->restart_block; |
| return restart->fn(restart); |
| } |
| |
| long do_no_restart_syscall(struct restart_block *param) |
| { |
| return -EINTR; |
| } |
| |
| static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset) |
| { |
| if (task_sigpending(tsk) && !thread_group_empty(tsk)) { |
| sigset_t newblocked; |
| /* A set of now blocked but previously unblocked signals. */ |
| sigandnsets(&newblocked, newset, ¤t->blocked); |
| retarget_shared_pending(tsk, &newblocked); |
| } |
| tsk->blocked = *newset; |
| recalc_sigpending(); |
| } |
| |
| /** |
| * set_current_blocked - change current->blocked mask |
| * @newset: new mask |
| * |
| * It is wrong to change ->blocked directly, this helper should be used |
| * to ensure the process can't miss a shared signal we are going to block. |
| */ |
| void set_current_blocked(sigset_t *newset) |
| { |
| sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP)); |
| __set_current_blocked(newset); |
| } |
| |
| void __set_current_blocked(const sigset_t *newset) |
| { |
| struct task_struct *tsk = current; |
| |
| /* |
| * In case the signal mask hasn't changed, there is nothing we need |
| * to do. The current->blocked shouldn't be modified by other task. |
| */ |
| if (sigequalsets(&tsk->blocked, newset)) |
| return; |
| |
| spin_lock_irq(&tsk->sighand->siglock); |
| __set_task_blocked(tsk, newset); |
| spin_unlock_irq(&tsk->sighand->siglock); |
| } |
| |
| /* |
| * This is also useful for kernel threads that want to temporarily |
| * (or permanently) block certain signals. |
| * |
| * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel |
| * interface happily blocks "unblockable" signals like SIGKILL |
| * and friends. |
| */ |
| int sigprocmask(int how, sigset_t *set, sigset_t *oldset) |
| { |
| struct task_struct *tsk = current; |
| sigset_t newset; |
| |
| /* Lockless, only current can change ->blocked, never from irq */ |
| if (oldset) |
| *oldset = tsk->blocked; |
| |
| switch (how) { |
| case SIG_BLOCK: |
| sigorsets(&newset, &tsk->blocked, set); |
| break; |
| case SIG_UNBLOCK: |
| sigandnsets(&newset, &tsk->blocked, set); |
| break; |
| case SIG_SETMASK: |
| newset = *set; |
| break; |
| default: |
| return -EINVAL; |
| } |
| |
| __set_current_blocked(&newset); |
| return 0; |
| } |
| EXPORT_SYMBOL(sigprocmask); |
| |
| /* |
| * The api helps set app-provided sigmasks. |
| * |
| * This is useful for syscalls such as ppoll, pselect, io_pgetevents and |
| * epoll_pwait where a new sigmask is passed from userland for the syscalls. |
| * |
| * Note that it does set_restore_sigmask() in advance, so it must be always |
| * paired with restore_saved_sigmask_unless() before return from syscall. |
| */ |
| int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize) |
| { |
| sigset_t kmask; |
| |
| if (!umask) |
| return 0; |
| if (sigsetsize != sizeof(sigset_t)) |
| return -EINVAL; |
| if (copy_from_user(&kmask, umask, sizeof(sigset_t))) |
| return -EFAULT; |
| |
| set_restore_sigmask(); |
| current->saved_sigmask = current->blocked; |
| set_current_blocked(&kmask); |
| |
| return 0; |
| } |
| |
| #ifdef CONFIG_COMPAT |
| int set_compat_user_sigmask(const compat_sigset_t __user *umask, |
| size_t sigsetsize) |
| { |
| sigset_t kmask; |
| |
| if (!umask) |
| return 0; |
| if (sigsetsize != sizeof(compat_sigset_t)) |
| return -EINVAL; |
| if (get_compat_sigset(&kmask, umask)) |
| return -EFAULT; |
| |
| set_restore_sigmask(); |
| current->saved_sigmask = current->blocked; |
| set_current_blocked(&kmask); |
| |
| return 0; |
| } |
| #endif |
| |
| /** |
| * sys_rt_sigprocmask - change the list of currently blocked signals |
| * @how: whether to add, remove, or set signals |
| * @nset: stores pending signals |
| * @oset: previous value of signal mask if non-null |
| * @sigsetsize: size of sigset_t type |
| */ |
| SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset, |
| sigset_t __user *, oset, size_t, sigsetsize) |
| { |
| sigset_t old_set, new_set; |
| int error; |
| |
| /* XXX: Don't preclude handling different sized sigset_t's. */ |
| if (sigsetsize != sizeof(sigset_t)) |
| return -EINVAL; |
| |
| old_set = current->blocked; |
| |
| if (nset) { |
| if (copy_from_user(&new_set, nset, sizeof(sigset_t))) |
| return -EFAULT; |
| sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); |
| |
| error = sigprocmask(how, &new_set, NULL); |
| if (error) |
| return error; |
| } |
| |
| if (oset) { |
| if (copy_to_user(oset, &old_set, sizeof(sigset_t))) |
| return -EFAULT; |
| } |
| |
| return 0; |
| } |
| |
| #ifdef CONFIG_COMPAT |
| COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset, |
| compat_sigset_t __user *, oset, compat_size_t, sigsetsize) |
| { |
| sigset_t old_set = current->blocked; |
| |
| /* XXX: Don't preclude handling different sized sigset_t's. */ |
| if (sigsetsize != sizeof(sigset_t)) |
| return -EINVAL; |
| |
| if (nset) { |
| sigset_t new_set; |
| int error; |
| if (get_compat_sigset(&new_set, nset)) |
| return -EFAULT; |
| sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); |
| |
| error = sigprocmask(how, &new_set, NULL); |
| if (error) |
| return error; |
| } |
| return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0; |
| } |
| #endif |
| |
| static void do_sigpending(sigset_t *set) |
| { |
| spin_lock_irq(¤t->sighand->siglock); |
| sigorsets(set, ¤t->pending.signal, |
| ¤t->signal->shared_pending.signal); |
| spin_unlock_irq(¤t->sighand->siglock); |
| |
| /* Outside the lock because only this thread touches it. */ |
| sigandsets(set, ¤t->blocked, set); |
| } |
| |
| /** |
| * sys_rt_sigpending - examine a pending signal that has been raised |
| * while blocked |
| * @uset: stores pending signals |
| * @sigsetsize: size of sigset_t type or larger |
| */ |
| SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize) |
| { |
| sigset_t set; |
| |
| if (sigsetsize > sizeof(*uset)) |
| return -EINVAL; |
| |
| do_sigpending(&set); |
| |
| if (copy_to_user(uset, &set, sigsetsize)) |
| return -EFAULT; |
| |
| return 0; |
| } |
| |
| #ifdef CONFIG_COMPAT |
| COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset, |
| compat_size_t, sigsetsize) |
| { |
| sigset_t set; |
| |
| if (sigsetsize > sizeof(*uset)) |
| return -EINVAL; |
| |
| do_sigpending(&set); |
| |
| return put_compat_sigset(uset, &set, sigsetsize); |
| } |
| #endif |
| |
| static const struct { |
| unsigned |