/* * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define CREATE_TRACE_POINTS #include #include #include #include #include #include "audit.h" /* audit_signal_info() */ /* * 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 int 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 int sig_task_ignored(struct task_struct *t, int sig, int from_ancestor_ns) { void __user *handler; handler = sig_handler(t, sig); if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) && handler == SIG_DFL && !from_ancestor_ns) return 1; return sig_handler_ignored(handler, sig); } static int sig_ignored(struct task_struct *t, int sig, int from_ancestor_ns) { /* * 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 0; if (!sig_task_ignored(t, sig, from_ancestor_ns)) return 0; /* * Tracers may want to know about even ignored signals. */ return !tracehook_consider_ignored_signal(t, sig); } /* * Re-calculate pending state from the set of locally pending * signals, globally pending signals, and blocked signals. */ static inline int 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 int recalc_sigpending_tsk(struct task_struct *t) { if (t->signal->group_stop_count > 0 || PENDING(&t->pending, &t->blocked) || PENDING(&t->signal->shared_pending, &t->blocked)) { set_tsk_thread_flag(t, TIF_SIGPENDING); return 1; } /* * 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 0; } /* * 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 (unlikely(tracehook_force_sigpending())) set_thread_flag(TIF_SIGPENDING); else if (!recalc_sigpending_tsk(current) && !freezing(current)) clear_thread_flag(TIF_SIGPENDING); } /* 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)) 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; printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n", current->comm, current->pid, sig); } /* * 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 flags, int override_rlimit) { struct sigqueue *q = NULL; struct user_struct *user; /* * Protect access to @t credentials. This can go away when all * callers hold rcu read lock. */ rcu_read_lock(); user = get_uid(__task_cred(t)->user); atomic_inc(&user->sigpending); rcu_read_unlock(); if (override_rlimit || atomic_read(&user->sigpending) <= task_rlimit(t, RLIMIT_SIGPENDING)) { q = kmem_cache_alloc(sigqueue_cachep, flags); } else { print_dropped_signal(sig); } if (unlikely(q == NULL)) { atomic_dec(&user->sigpending); free_uid(user); } else { INIT_LIST_HEAD(&q->list); q->flags = 0; q->user = user; } return q; } static void __sigqueue_free(struct sigqueue *q) { if (q->flags & SIGQUEUE_PREALLOC) return; atomic_dec(&q->user->sigpending); free_uid(q->user); 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 a task. */ void __flush_signals(struct task_struct *t) { clear_tsk_thread_flag(t, TIF_SIGPENDING); flush_sigqueue(&t->pending); flush_sigqueue(&t->signal->shared_pending); } void flush_signals(struct task_struct *t) { unsigned long flags; spin_lock_irqsave(&t->sighand->siglock, flags); __flush_signals(t); spin_unlock_irqrestore(&t->sighand->siglock, flags); } 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); } 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; sigemptyset(&ka->sa.sa_mask); ka++; } } int 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 1; if (handler != SIG_IGN && handler != SIG_DFL) return 0; return !tracehook_consider_fatal_signal(tsk, sig); } /* * Notify the system that a driver wants to block all signals for this * process, and wants to be notified if any signals at all were to be * sent/acted upon. If the notifier routine returns non-zero, then the * signal will be acted upon after all. If the notifier routine returns 0, * then then signal will be blocked. Only one block per process is * allowed. priv is a pointer to private data that the notifier routine * can use to determine if the signal should be blocked or not. */ void block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask) { unsigned long flags; spin_lock_irqsave(¤t->sighand->siglock, flags); current->notifier_mask = mask; current->notifier_data = priv; current->notifier = notifier; spin_unlock_irqrestore(¤t->sighand->siglock, flags); } /* Notify the system that blocking has ended. */ void unblock_all_signals(void) { unsigned long flags; spin_lock_irqsave(¤t->sighand->siglock, flags); current->notifier = NULL; current->notifier_data = NULL; recalc_sigpending(); spin_unlock_irqrestore(¤t->sighand->siglock, flags); } static void collect_signal(int sig, struct sigpending *list, siginfo_t *info) { 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); __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. */ 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, siginfo_t *info) { int sig = next_signal(pending, mask); if (sig) { if (current->notifier) { if (sigismember(current->notifier_mask, sig)) { if (!(current->notifier)(current->notifier_data)) { clear_thread_flag(TIF_SIGPENDING); return 0; } } } collect_signal(sig, pending, info); } 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, siginfo_t *info) { int signr; /* We only dequeue private signals from ourselves, we don't let * signalfd steal them */ signr = __dequeue_signal(&tsk->pending, mask, info); if (!signr) { signr = __dequeue_signal(&tsk->signal->shared_pending, mask, info); /* * 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.tv64 != 0) { hrtimer_forward(tmr, tmr->base->get_time(), tsk->signal->it_real_incr); hrtimer_restart(tmr); } } } 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. */ tsk->signal->flags |= SIGNAL_STOP_DEQUEUED; } if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) { /* * 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); do_schedule_next_timer(info); spin_lock(&tsk->sighand->siglock); } return signr; } /* * 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(struct task_struct *t, int resume) { unsigned int mask; set_tsk_thread_flag(t, TIF_SIGPENDING); /* * For SIGKILL, we want to 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. */ mask = TASK_INTERRUPTIBLE; if (resume) mask |= TASK_WAKEKILL; if (!wake_up_state(t, mask)) 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. * * This version takes a sigset mask and looks at all signals, * not just those in the first mask word. */ static int rm_from_queue_full(sigset_t *mask, struct sigpending *s) { struct sigqueue *q, *n; sigset_t m; sigandsets(&m, mask, &s->signal); if (sigisemptyset(&m)) return 0; signandsets(&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); } } return 1; } /* * 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 int rm_from_queue(unsigned long mask, struct sigpending *s) { struct sigqueue *q, *n; if (!sigtestsetmask(&s->signal, mask)) return 0; sigdelsetmask(&s->signal, mask); list_for_each_entry_safe(q, n, &s->list, list) { if (q->info.si_signo < SIGRTMIN && (mask & sigmask(q->info.si_signo))) { list_del_init(&q->list); __sigqueue_free(q); } } return 1; } static inline int is_si_special(const struct siginfo *info) { return info <= SEND_SIG_FORCED; } static inline bool si_fromuser(const struct siginfo *info) { return info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)); } /* * called with RCU read lock from check_kill_permission() */ static int kill_ok_by_cred(struct task_struct *t) { const struct cred *cred = current_cred(); const struct cred *tcred = __task_cred(t); if (cred->user->user_ns == tcred->user->user_ns && (cred->euid == tcred->suid || cred->euid == tcred->uid || cred->uid == tcred->suid || cred->uid == tcred->uid)) return 1; if (ns_capable(tcred->user->user_ns, CAP_KILL)) return 1; return 0; } /* * Bad permissions for sending the signal * - the caller must hold the RCU read lock */ static int check_kill_permission(int sig, struct 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; default: return -EPERM; } } return security_task_kill(t, info, sig, 0); } /* * 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 int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns) { struct signal_struct *signal = p->signal; struct task_struct *t; if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) { /* * The process is in the middle of dying, nothing to do. */ } else if (sig_kernel_stop(sig)) { /* * This is a stop signal. Remove SIGCONT from all queues. */ rm_from_queue(sigmask(SIGCONT), &signal->shared_pending); t = p; do { rm_from_queue(sigmask(SIGCONT), &t->pending); } while_each_thread(p, t); } else if (sig == SIGCONT) { unsigned int why; /* * Remove all stop signals from all queues, * and wake all threads. */ rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending); t = p; do { unsigned int state; rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending); /* * If there is a handler for SIGCONT, we must make * sure that no thread returns to user mode before * we post the signal, in case it was the only * thread eligible to run the signal handler--then * it must not do anything between resuming and * running the handler. With the TIF_SIGPENDING * flag set, the thread will pause and acquire the * siglock that we hold now and until we've queued * the pending signal. * * Wake up the stopped thread _after_ setting * TIF_SIGPENDING */ state = __TASK_STOPPED; if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) { set_tsk_thread_flag(t, TIF_SIGPENDING); state |= TASK_INTERRUPTIBLE; } wake_up_state(t, state); } while_each_thread(p, 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_to_deliver(). */ signal->flags = why | SIGNAL_STOP_CONTINUED; signal->group_stop_count = 0; signal->group_exit_code = 0; } else { /* * We are not stopped, but there could be a stop * signal in the middle of being processed after * being removed from the queue. Clear that too. */ signal->flags &= ~SIGNAL_STOP_DEQUEUED; } } return !sig_ignored(p, sig, from_ancestor_ns); } /* * 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 int wants_signal(int sig, struct task_struct *p) { if (sigismember(&p->blocked, sig)) return 0; if (p->flags & PF_EXITING) return 0; if (sig == SIGKILL) return 1; if (task_is_stopped_or_traced(p)) return 0; return task_curr(p) || !signal_pending(p); } static void complete_signal(int sig, struct task_struct *p, int group) { struct signal_struct *signal = p->signal; struct task_struct *t; /* * 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 (!group || 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->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) && !sigismember(&t->real_blocked, sig) && (sig == SIGKILL || !tracehook_consider_fatal_signal(t, sig))) { /* * 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 { sigaddset(&t->pending.signal, SIGKILL); 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 int legacy_queue(struct sigpending *signals, int sig) { return (sig < SIGRTMIN) && sigismember(&signals->signal, sig); } static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, int group, int from_ancestor_ns) { struct sigpending *pending; struct sigqueue *q; int override_rlimit; trace_signal_generate(sig, info, t); assert_spin_locked(&t->sighand->siglock); if (!prepare_signal(sig, t, from_ancestor_ns)) return 0; pending = group ? &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. */ if (legacy_queue(pending, sig)) return 0; /* * fast-pathed signals for kernel-internal things like SIGSTOP * or SIGKILL. */ if (info == SEND_SIG_FORCED) 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 | __GFP_NOTRACK_FALSE_POSITIVE, override_rlimit); if (q) { list_add_tail(&q->list, &pending->list); switch ((unsigned long) info) { case (unsigned long) SEND_SIG_NOINFO: 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)); q->info.si_uid = current_uid(); break; case (unsigned long) SEND_SIG_PRIV: 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); if (from_ancestor_ns) q->info.si_pid = 0; break; } } else if (!is_si_special(info)) { if (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(). */ trace_signal_overflow_fail(sig, group, info); return -EAGAIN; } else { /* * This is a silent loss of information. We still * send the signal, but the *info bits are lost. */ trace_signal_lose_info(sig, group, info); } } out_set: signalfd_notify(t, sig); sigaddset(&pending->signal, sig); complete_signal(sig, t, group); return 0; } static int send_signal(int sig, struct siginfo *info, struct task_struct *t, int group) { int from_ancestor_ns = 0; #ifdef CONFIG_PID_NS from_ancestor_ns = si_fromuser(info) && !task_pid_nr_ns(current, task_active_pid_ns(t)); #endif return __send_signal(sig, info, t, group, from_ancestor_ns); } static void print_fatal_signal(struct pt_regs *regs, int signr) { printk("%s/%d: potentially unexpected fatal signal %d.\n", current->comm, task_pid_nr(current), signr); #if defined(__i386__) && !defined(__arch_um__) printk("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; printk("%02x ", insn); } } #endif printk("\n"); 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 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p) { return send_signal(sig, info, p, 1); } static int specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t) { return send_signal(sig, info, t, 0); } int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p, bool group) { unsigned long flags; int ret = -ESRCH; if (lock_task_sighand(p, &flags)) { ret = send_signal(sig, info, p, group); unlock_task_sighand(p, &flags); } return ret; } /* * 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. */ int force_sig_info(int sig, struct siginfo *info, struct task_struct *t) { unsigned long int flags; int ret, blocked, ignored; struct k_sigaction *action; 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) { action->sa.sa_handler = SIG_DFL; if (blocked) { sigdelset(&t->blocked, sig); recalc_sigpending_and_wake(t); } } if (action->sa.sa_handler == SIG_DFL) t->signal->flags &= ~SIGNAL_UNKILLABLE; ret = specific_send_sig_info(sig, info, t); spin_unlock_irqrestore(&t->sighand->siglock, flags); return ret; } /* * 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) { 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; spin_lock_irqsave(&sighand->siglock, *flags); if (likely(sighand == tsk->sighand)) break; spin_unlock_irqrestore(&sighand->siglock, *flags); } rcu_read_unlock(); return sighand; } /* * send signal info to all the members of a group */ int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p) { 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, true); 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 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); success |= !err; retval = err; } while_each_pid_task(pgrp, PIDTYPE_PGID, p); return success ? 0 : retval; } int kill_pid_info(int sig, struct siginfo *info, struct pid *pid) { int error = -ESRCH; struct task_struct *p; rcu_read_lock(); retry: p = pid_task(pid, PIDTYPE_PID); if (p) { error = group_send_sig_info(sig, info, p); if (unlikely(error == -ESRCH)) /* * 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. */ goto retry; } rcu_read_unlock(); return error; } int kill_proc_info(int sig, struct siginfo *info, pid_t pid) { int error; rcu_read_lock(); error = kill_pid_info(sig, info, find_vpid(pid)); rcu_read_unlock(); return error; } /* like kill_pid_info(), but doesn't use uid/euid of "current" */ int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid, uid_t uid, uid_t euid, u32 secid) { int ret = -EINVAL; struct task_struct *p; const struct cred *pcred; unsigned long flags; if (!valid_signal(sig)) return ret; rcu_read_lock(); p = pid_task(pid, PIDTYPE_PID); if (!p) { ret = -ESRCH; goto out_unlock; } pcred = __task_cred(p); if (si_fromuser(info) && euid != pcred->suid && euid != pcred->uid && uid != pcred->suid && uid != pcred->uid) { ret = -EPERM; goto out_unlock; } ret = security_task_kill(p, info, sig, secid); if (ret) goto out_unlock; if (sig) { if (lock_task_sighand(p, &flags)) { ret = __send_signal(sig, info, p, 1, 0); unlock_task_sighand(p, &flags); } else ret = -ESRCH; } out_unlock: rcu_read_unlock(); return ret; } EXPORT_SYMBOL_GPL(kill_pid_info_as_uid); /* * 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 siginfo *info, pid_t pid) { int ret; if (pid > 0) { rcu_read_lock(); ret = kill_pid_info(sig, info, find_vpid(pid)); rcu_read_unlock(); return ret; } 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); ++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 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, false); } #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); } void force_sig(int sig, struct task_struct *p) { force_sig_info(sig, SEND_SIG_PRIV, p); } /* * 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.. */ int force_sigsegv(int sig, struct task_struct *p) { if (sig == SIGSEGV) { unsigned long flags; spin_lock_irqsave(&p->sighand->siglock, flags); p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL; spin_unlock_irqrestore(&p->sighand->siglock, flags); } force_sig(SIGSEGV, p); return 0; } 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) { struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0); if (q) q->flags |= SIGQUEUE_PREALLOC; return q; } 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 task_struct *t, int group) { int sig = q->info.si_signo; struct sigpending *pending; unsigned long flags; int ret; BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); ret = -1; if (!likely(lock_task_sighand(t, &flags))) goto ret; ret = 1; /* the signal is ignored */ if (!prepare_signal(sig, t, 0)) 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++; goto out; } q->info.si_overrun = 0; signalfd_notify(t, sig); pending = group ? &t->signal->shared_pending : &t->pending; list_add_tail(&q->list, &pending->list); sigaddset(&pending->signal, sig); complete_signal(sig, t, group); out: unlock_task_sighand(t, &flags); ret: return ret; } /* * Let a parent know about the death of a child. * For a stopped/continued status change, use do_notify_parent_cldstop instead. * * Returns -1 if our parent ignored us and so we've switched to * self-reaping, or else @sig. */ int do_notify_parent(struct task_struct *tsk, int sig) { struct siginfo info; unsigned long flags; struct sighand_struct *psig; int ret = sig; BUG_ON(sig == -1); /* do_notify_parent_cldstop should have been called instead. */ BUG_ON(task_is_stopped_or_traced(tsk)); BUG_ON(!task_ptrace(tsk) && (tsk->group_leader != tsk || !thread_group_empty(tsk))); info.si_signo = sig; info.si_errno = 0; /* * we are under tasklist_lock here so our parent is tied to * us and cannot exit and release its namespace. * * the only it can is to switch its nsproxy with sys_unshare, * bu uncharing pid namespaces is not allowed, so we'll always * see relevant namespace * * 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, tsk->parent->nsproxy->pid_ns); info.si_uid = __task_cred(tsk)->uid; rcu_read_unlock(); info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime, tsk->signal->utime)); info.si_stime = cputime_to_clock_t(cputime_add(tsk->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 (!task_ptrace(tsk) && 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). */ ret = tsk->exit_signal = -1; if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) sig = -1; } if (valid_signal(sig) && sig > 0) __group_send_sig_info(sig, &info, tsk->parent); __wake_up_parent(tsk, tsk->parent); spin_unlock_irqrestore(&psig->siglock, flags); return ret; } static void do_notify_parent_cldstop(struct task_struct *tsk, int why) { struct siginfo info; unsigned long flags; struct task_struct *parent; struct sighand_struct *sighand; if (task_ptrace(tsk)) parent = tsk->parent; else { tsk = tsk->group_leader; parent = tsk->real_parent; } 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, parent->nsproxy->pid_ns); info.si_uid = __task_cred(tsk)->uid; rcu_read_unlock(); info.si_utime = cputime_to_clock_t(tsk->utime); info.si_stime = cputime_to_clock_t(tsk->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)) __group_send_sig_info(SIGCHLD, &info, parent); /* * Even if SIGCHLD is not generated, we must wake up wait4 calls. */ __wake_up_parent(tsk, parent); spin_unlock_irqrestore(&sighand->siglock, flags); } static inline int may_ptrace_stop(void) { if (!likely(task_ptrace(current))) return 0; /* * Are we in the middle of do_coredump? * If so and our tracer is also part of the coredump stopping * is a deadlock situation, and pointless because our tracer * is dead so don't allow us to stop. * If SIGKILL was already sent before the caller unlocked * ->siglock we must see ->core_state != NULL. Otherwise it * is safe to enter schedule(). */ if (unlikely(current->mm->core_state) && unlikely(current->mm == current->parent->mm)) return 0; return 1; } /* * Return non-zero if there is a SIGKILL that should be waking us up. * Called with the siglock held. */ static int sigkill_pending(struct task_struct *tsk) { return sigismember(&tsk->pending.signal, SIGKILL) || sigismember(&tsk->signal->shared_pending.signal, SIGKILL); } /* * 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. * * If we actually decide not to stop at all because the tracer * is gone, we keep current->exit_code unless clear_code. */ static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info) __releases(¤t->sighand->siglock) __acquires(¤t->sighand->siglock) { if (arch_ptrace_stop_needed(exit_code, info)) { /* * 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. * Meanwhile, a SIGKILL could come in before we retake the * siglock. That must prevent us from sleeping in TASK_TRACED. * So after regaining the lock, we must check for SIGKILL. */ spin_unlock_irq(¤t->sighand->siglock); arch_ptrace_stop(exit_code, info); spin_lock_irq(¤t->sighand->siglock); if (sigkill_pending(current)) return; } /* * If there is a group stop in progress, * we must participate in the bookkeeping. */ if (current->signal->group_stop_count > 0) --current->signal->group_stop_count; current->last_siginfo = info; current->exit_code = exit_code; /* Let the debugger run. */ __set_current_state(TASK_TRACED); spin_unlock_irq(¤t->sighand->siglock); read_lock(&tasklist_lock); if (may_ptrace_stop()) { do_notify_parent_cldstop(current, CLD_TRAPPED); /* * 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); preempt_enable_no_resched(); schedule(); } else { /* * By the time we got the lock, our tracer went away. * Don't drop the lock yet, another tracer may come. */ __set_current_state(TASK_RUNNING); if (clear_code) current->exit_code = 0; read_unlock(&tasklist_lock); } /* * While in TASK_TRACED, we were considered "frozen enough". * Now that we woke up, it's crucial if we're supposed to be * frozen that we freeze now before running anything substantial. */ try_to_freeze(); /* * 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); current->last_siginfo = NULL; /* * 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); } void ptrace_notify(int exit_code) { siginfo_t info; BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP); memset(&info, 0, sizeof info); info.si_signo = SIGTRAP; info.si_code = exit_code; info.si_pid = task_pid_vnr(current); info.si_uid = current_uid(); /* Let the debugger run. */ spin_lock_irq(¤t->sighand->siglock); ptrace_stop(exit_code, 1, &info); spin_unlock_irq(¤t->sighand->siglock); } /* * This performs the stopping for SIGSTOP and other stop signals. * We have to stop all threads in the thread group. * Returns non-zero if we've actually stopped and released the siglock. * Returns zero if we didn't stop and still hold the siglock. */ static int do_signal_stop(int signr) { struct signal_struct *sig = current->signal; int notify; if (!sig->group_stop_count) { struct task_struct *t; if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) || unlikely(signal_group_exit(sig))) return 0; /* * There is no group stop already in progress. * We must initiate one now. */ sig->group_exit_code = signr; sig->group_stop_count = 1; for (t = next_thread(current); t != current; t = next_thread(t)) /* * Setting state to TASK_STOPPED for a group * stop is always done with the siglock held, * so this check has no races. */ if (!(t->flags & PF_EXITING) && !task_is_stopped_or_traced(t)) { sig->group_stop_count++; signal_wake_up(t, 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. When ptraced, every thread reports itself. */ notify = sig->group_stop_count == 1 ? CLD_STOPPED : 0; notify = tracehook_notify_jctl(notify, CLD_STOPPED); /* * tracehook_notify_jctl() can drop and reacquire siglock, so * we keep ->group_stop_count != 0 before the call. If SIGCONT * or SIGKILL comes in between ->group_stop_count == 0. */ if (sig->group_stop_count) { if (!--sig->group_stop_count) sig->flags = SIGNAL_STOP_STOPPED; current->exit_code = sig->group_exit_code; __set_current_state(TASK_STOPPED); } spin_unlock_irq(¤t->sighand->siglock); if (notify) { read_lock(&tasklist_lock); do_notify_parent_cldstop(current, notify); read_unlock(&tasklist_lock); } /* Now we don't run again until woken by SIGCONT or SIGKILL */ do { schedule(); } while (try_to_freeze()); tracehook_finish_jctl(); current->exit_code = 0; return 1; } static int ptrace_signal(int signr, siginfo_t *info, struct pt_regs *regs, void *cookie) { if (!task_ptrace(current)) return signr; ptrace_signal_deliver(regs, cookie); /* Let the debugger run. */ ptrace_stop(signr, 0, info); /* We're back. Did the debugger cancel the sig? */ signr = current->exit_code; if (signr == 0) return signr; current->exit_code = 0; /* * 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) { info->si_signo = signr; info->si_errno = 0; info->si_code = SI_USER; info->si_pid = task_pid_vnr(current->parent); info->si_uid = task_uid(current->parent); } /* If the (new) signal is now blocked, requeue it. */ if (sigismember(¤t->blocked, signr)) { specific_send_sig_info(signr, info, current); signr = 0; } return signr; } int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka, struct pt_regs *regs, void *cookie) { struct sighand_struct *sighand = current->sighand; struct signal_struct *signal = current->signal; int signr; relock: /* * We'll jump back here after any time we were stopped in TASK_STOPPED. * While in TASK_STOPPED, we were considered "frozen enough". * Now that we woke up, it's crucial if we're supposed to be * frozen that we freeze now before running anything substantial. */ try_to_freeze(); 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 = (signal->flags & SIGNAL_STOP_CONTINUED) ? CLD_CONTINUED : CLD_STOPPED; signal->flags &= ~SIGNAL_CLD_MASK; why = tracehook_notify_jctl(why, CLD_CONTINUED); spin_unlock_irq(&sighand->siglock); if (why) { read_lock(&tasklist_lock); do_notify_parent_cldstop(current->group_leader, why); read_unlock(&tasklist_lock); } goto relock; } for (;;) { struct k_sigaction *ka; /* * Tracing can induce an artifical signal and choose sigaction. * The return value in @signr determines the default action, * but @info->si_signo is the signal number we will report. */ signr = tracehook_get_signal(current, regs, info, return_ka); if (unlikely(signr < 0)) goto relock; if (unlikely(signr != 0)) ka = return_ka; else { if (unlikely(signal->group_stop_count > 0) && do_signal_stop(0)) goto relock; signr = dequeue_signal(current, ¤t->blocked, info); if (!signr) break; /* will return 0 */ if (signr != SIGKILL) { signr = ptrace_signal(signr, info, regs, cookie); if (!signr) continue; } ka = &sighand->action[signr-1]; } /* Trace actually delivered signals. */ trace_signal_deliver(signr, info, ka); if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */ continue; if (ka->sa.sa_handler != SIG_DFL) { /* Run the handler. */ *return_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(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; } spin_unlock_irq(&sighand->siglock); /* * 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(regs, info->si_signo); /* * 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(info->si_signo, info->si_signo, regs); } /* * Death signals, no core dump. */ do_group_exit(info->si_signo); /* NOTREACHED */ } spin_unlock_irq(&sighand->siglock); return signr; } void exit_signals(struct task_struct *tsk) { int group_stop = 0; struct task_struct *t; if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) { tsk->flags |= PF_EXITING; 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; if (!signal_pending(tsk)) goto out; /* * It could be that __group_complete_signal() choose us to * notify about group-wide signal. Another thread should be * woken now to take the signal since we will not. */ for (t = tsk; (t = next_thread(t)) != tsk; ) if (!signal_pending(t) && !(t->flags & PF_EXITING)) recalc_sigpending_and_wake(t); if (unlikely(tsk->signal->group_stop_count) && !--tsk->signal->group_stop_count) { tsk->signal->flags = SIGNAL_STOP_STOPPED; group_stop = tracehook_notify_jctl(CLD_STOPPED, CLD_STOPPED); } out: spin_unlock_irq(&tsk->sighand->siglock); if (unlikely(group_stop)) { read_lock(&tasklist_lock); do_notify_parent_cldstop(tsk, group_stop); read_unlock(&tasklist_lock); } } EXPORT_SYMBOL(recalc_sigpending); EXPORT_SYMBOL_GPL(dequeue_signal); EXPORT_SYMBOL(flush_signals); EXPORT_SYMBOL(force_sig); EXPORT_SYMBOL(send_sig); EXPORT_SYMBOL(send_sig_info); EXPORT_SYMBOL(sigprocmask); EXPORT_SYMBOL(block_all_signals); EXPORT_SYMBOL(unblock_all_signals); /* * System call entry points. */ /** * sys_restart_syscall - restart a system call */ SYSCALL_DEFINE0(restart_syscall) { struct restart_block *restart = ¤t_thread_info()->restart_block; return restart->fn(restart); } long do_no_restart_syscall(struct restart_block *param) { return -EINTR; } /* * We don't need to get the kernel lock - this is all local to this * particular thread.. (and that's good, because this is _heavily_ * used by various programs) */ /* * 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) { int error; spin_lock_irq(¤t->sighand->siglock); if (oldset) *oldset = current->blocked; error = 0; switch (how) { case SIG_BLOCK: sigorsets(¤t->blocked, ¤t->blocked, set); break; case SIG_UNBLOCK: signandsets(¤t->blocked, ¤t->blocked, set); break; case SIG_SETMASK: current->blocked = *set; break; default: error = -EINVAL; } recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); return error; } /** * sys_rt_sigprocmask - change the list of currently blocked signals * @how: whether to add, remove, or set signals * @set: 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 *, set, sigset_t __user *, oset, size_t, sigsetsize) { int error = -EINVAL; sigset_t old_set, new_set; /* XXX: Don't preclude handling different sized sigset_t's. */ if (sigsetsize != sizeof(sigset_t)) goto out; if (set) { error = -EFAULT; if (copy_from_user(&new_set, set, sizeof(*set))) goto out; sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); error = sigprocmask(how, &new_set, &old_set); if (error) goto out; if (oset) goto set_old; } else if (oset) { spin_lock_irq(¤t->sighand->siglock); old_set = current->blocked; spin_unlock_irq(¤t->sighand->siglock); set_old: error = -EFAULT; if (copy_to_user(oset, &old_set, sizeof(*oset))) goto out; } error = 0; out: return error; } long do_sigpending(void __user *set, unsigned long sigsetsize) { long error = -EINVAL; sigset_t pending; if (sigsetsize > sizeof(sigset_t)) goto out; spin_lock_irq(¤t->sighand->siglock); sigorsets(&pending, ¤t->pending.signal, ¤t->signal->shared_pending.signal); spin_unlock_irq(¤t->sighand->siglock); /* Outside the lock because only this thread touches it. */ sigandsets(&pending, ¤t->blocked, &pending); error = -EFAULT; if (!copy_to_user(set, &pending, sigsetsize)) error = 0; out: return error; } /** * sys_rt_sigpending - examine a pending signal that has been raised * while blocked * @set: stores pending signals * @sigsetsize: size of sigset_t type or larger */ SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize) { return do_sigpending(set, sigsetsize); } #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from) { int err; if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t))) return -EFAULT; if (from->si_code < 0) return __copy_to_user(to, from, sizeof(siginfo_t)) ? -EFAULT : 0; /* * If you change siginfo_t structure, please be sure * this code is fixed accordingly. * Please remember to update the signalfd_copyinfo() function * inside fs/signalfd.c too, in case siginfo_t changes. * It should never copy any pad contained in the structure * to avoid security leaks, but must copy the generic * 3 ints plus the relevant union member. */ err = __put_user(from->si_signo, &to->si_signo); err |= __put_user(from->si_errno, &to->si_errno); err |= __put_user((short)from->si_code, &to->si_code); switch (from->si_code & __SI_MASK) { case __SI_KILL: err |= __put_user(from->si_pid, &to->si_pid); err |= __put_user(from->si_uid, &to->si_uid); break; case __SI_TIMER: err |= __put_user(from->si_tid, &to->si_tid); err |= __put_user(from->si_overrun, &to->si_overrun); err |= __put_user(from->si_ptr, &to->si_ptr); break; case __SI_POLL: err |= __put_user(from->si_band, &to->si_band); err |= __put_user(from->si_fd, &to->si_fd); break; case __SI_FAULT: err |= __put_user(from->si_addr, &to->si_addr); #ifdef __ARCH_SI_TRAPNO err |= __put_user(from->si_trapno, &to->si_trapno); #endif #ifdef BUS_MCEERR_AO /* * Other callers might not initialize the si_lsb field, * so check explicitly for the right codes here. */ if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO) err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb); #endif break; case __SI_CHLD: err |= __put_user(from->si_pid, &to->si_pid); err |= __put_user(from->si_uid, &to->si_uid); err |= __put_user(from->si_status, &to->si_status); err |= __put_user(from->si_utime, &to->si_utime); err |= __put_user(from->si_stime, &to->si_stime); break; case __SI_RT: /* This is not generated by the kernel as of now. */ case __SI_MESGQ: /* But this is */ err |= __put_user(from->si_pid, &to->si_pid); err |= __put_user(from->si_uid, &to->si_uid); err |= __put_user(from->si_ptr, &to->si_ptr); break; default: /* this is just in case for now ... */ err |= __put_user(from->si_pid, &to->si_pid); err |= __put_user(from->si_uid, &to->si_uid); break; } return err; } #endif /** * sys_rt_sigtimedwait - synchronously wait for queued signals specified * in @uthese * @uthese: queued signals to wait for * @uinfo: if non-null, the signal's siginfo is returned here * @uts: upper bound on process time suspension * @sigsetsize: size of sigset_t type */ SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese, siginfo_t __user *, uinfo, const struct timespec __user *, uts, size_t, sigsetsize) { int ret, sig; sigset_t these; struct timespec ts; siginfo_t info; long timeout = 0; /* XXX: Don't preclude handling different sized sigset_t's. */ if (sigsetsize != sizeof(sigset_t)) return -EINVAL; if (copy_from_user(&these, uthese, sizeof(these))) return -EFAULT; /* * Invert the set of allowed signals to get those we * want to block. */ sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP)); signotset(&these); if (uts) { if (copy_from_user(&ts, uts, sizeof(ts))) return -EFAULT; if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0 || ts.tv_sec < 0) return -EINVAL; } spin_lock_irq(¤t->sighand->siglock); sig = dequeue_signal(current, &these, &info); if (!sig) { timeout = MAX_SCHEDULE_TIMEOUT; if (uts) timeout = (timespec_to_jiffies(&ts) + (ts.tv_sec || ts.tv_nsec)); if (timeout) { /* * None ready -- temporarily unblock those we're * interested while we are sleeping in so that we'll * be awakened when they arrive. */ current->real_blocked = current->blocked; sigandsets(¤t->blocked, ¤t->blocked, &these); recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); timeout = schedule_timeout_interruptible(timeout); spin_lock_irq(¤t->sighand->siglock); sig = dequeue_signal(current, &these, &info); current->blocked = current->real_blocked; siginitset(¤t->real_blocked, 0); recalc_sigpending(); } } spin_unlock_irq(¤t->sighand->siglock); if (sig) { ret = sig; if (uinfo) { if (copy_siginfo_to_user(uinfo, &info)) ret = -EFAULT; } } else { ret = -EAGAIN; if (timeout) ret = -EINTR; } return ret; } /** * sys_kill - send a signal to a process * @pid: the PID of the process * @sig: signal to be sent */ SYSCALL_DEFINE2(kill, pid_t, pid, int, sig) { struct siginfo info; info.si_signo = sig; info.si_errno = 0; info.si_code = SI_USER; info.si_pid = task_tgid_vnr(current); info.si_uid = current_uid(); return kill_something_info(sig, &info, pid); } static int do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info) { struct task_struct *p; int error = -ESRCH; rcu_read_lock(); p = find_task_by_vpid(pid); if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) { error = check_kill_permission(sig, info, p); /* * The null signal is a permissions and process existence * probe. No signal is actually delivered. */ if (!error && sig) { error = do_send_sig_info(sig, info, p, false); /* * If lock_task_sighand() failed we pretend the task * dies after receiving the signal. The window is tiny, * and the signal is private anyway. */ if (unlikely(error == -ESRCH)) error = 0; } } rcu_read_unlock(); return error; } static int do_tkill(pid_t tgid, pid_t pid, int sig) { struct siginfo info; info.si_signo = sig; info.si_errno = 0; info.si_code = SI_TKILL; info.si_pid = task_tgid_vnr(current); info.si_uid = current_uid(); return do_send_specific(tgid, pid, sig, &info); } /** * sys_tgkill - send signal to one specific thread * @tgid: the thread group ID of the thread * @pid: the PID of the thread * @sig: signal to be sent * * This syscall also checks the @tgid and returns -ESRCH even if the PID * exists but it's not belonging to the target process anymore. This * method solves the problem of threads exiting and PIDs getting reused. */ SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig) { /* This is only valid for single tasks */ if (pid <= 0 || tgid <= 0) return -EINVAL; return do_tkill(tgid, pid, sig); } /** * sys_tkill - send signal to one specific task * @pid: the PID of the task * @sig: signal to be sent * * Send a signal to only one task, even if it's a CLONE_THREAD task. */ SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig) { /* This is only valid for single tasks */ if (pid <= 0) return -EINVAL; return do_tkill(0, pid, sig); } /** * sys_rt_sigqueueinfo - send signal information to a signal * @pid: the PID of the thread * @sig: signal to be sent * @uinfo: signal info to be sent */ SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig, siginfo_t __user *, uinfo) { siginfo_t info; if (copy_from_user(&info, uinfo, sizeof(siginfo_t))) return -EFAULT; /* Not even root can pretend to send signals from the kernel. * Nor can they impersonate a kill()/tgkill(), which adds source info. */ if (info.si_code >= 0 || info.si_code == SI_TKILL) { /* We used to allow any < 0 si_code */ WARN_ON_ONCE(info.si_code < 0); return -EPERM; } info.si_signo = sig; /* POSIX.1b doesn't mention process groups. */ return kill_proc_info(sig, &info, pid); } long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info) { /* This is only valid for single tasks */ if (pid <= 0 || tgid <= 0) return -EINVAL; /* Not even root can pretend to send signals from the kernel. * Nor can they impersonate a kill()/tgkill(), which adds source info. */ if (info->si_code >= 0 || info->si_code == SI_TKILL) { /* We used to allow any < 0 si_code */ WARN_ON_ONCE(info->si_code < 0); return -EPERM; } info->si_signo = sig; return do_send_specific(tgid, pid, sig, info); } SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig, siginfo_t __user *, uinfo) { siginfo_t info; if (copy_from_user(&info, uinfo, sizeof(siginfo_t))) return -EFAULT; return do_rt_tgsigqueueinfo(tgid, pid, sig, &info); } int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) { struct task_struct *t = current; struct k_sigaction *k; sigset_t mask; if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig))) return -EINVAL; k = &t->sighand->action[sig-1]; spin_lock_irq(¤t->sighand->siglock); if (oact) *oact = *k; if (act) { sigdelsetmask(&act->sa.sa_mask, sigmask(SIGKILL) | sigmask(SIGSTOP)); *k = *act; /* * POSIX 3.3.1.3: * "Setting a signal action to SIG_IGN for a signal that is * pending shall cause the pending signal to be discarded, * whether or not it is blocked." * * "Setting a signal action to SIG_DFL for a signal that is * pending and whose default action is to ignore the signal * (for example, SIGCHLD), shall cause the pending signal to * be discarded, whether or not it is blocked" */ if (sig_handler_ignored(sig_handler(t, sig), sig)) { sigemptyset(&mask); sigaddset(&mask, sig); rm_from_queue_full(&mask, &t->signal->shared_pending); do { rm_from_queue_full(&mask, &t->pending); t = next_thread(t); } while (t != current); } } spin_unlock_irq(¤t->sighand->siglock); return 0; } int do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp) { stack_t oss; int error; oss.ss_sp = (void __user *) current->sas_ss_sp; oss.ss_size = current->sas_ss_size; oss.ss_flags = sas_ss_flags(sp); if (uss) { void __user *ss_sp; size_t ss_size; int ss_flags; error = -EFAULT; if (!access_ok(VERIFY_READ, uss, sizeof(*uss))) goto out; error = __get_user(ss_sp, &uss->ss_sp) | __get_user(ss_flags, &uss->ss_flags) | __get_user(ss_size, &uss->ss_size); if (error) goto out; error = -EPERM; if (on_sig_stack(sp)) goto out; error = -EINVAL; /* * Note - this code used to test ss_flags incorrectly: * old code may have been written using ss_flags==0 * to mean ss_flags==SS_ONSTACK (as this was the only * way that worked) - this fix preserves that older * mechanism. */ if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0) goto out; if (ss_flags == SS_DISABLE) { ss_size = 0; ss_sp = NULL; } else { error = -ENOMEM; if (ss_size < MINSIGSTKSZ) goto out; } current->sas_ss_sp = (unsigned long) ss_sp; current->sas_ss_size = ss_size; } error = 0; if (uoss) { error = -EFAULT; if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss))) goto out; error = __put_user(oss.ss_sp, &uoss->ss_sp) | __put_user(oss.ss_size, &uoss->ss_size) | __put_user(oss.ss_flags, &uoss->ss_flags); } out: return error; } #ifdef __ARCH_WANT_SYS_SIGPENDING /** * sys_sigpending - examine pending signals * @set: where mask of pending signal is returned */ SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set) { return do_sigpending(set, sizeof(*set)); } #endif #ifdef __ARCH_WANT_SYS_SIGPROCMASK /** * sys_sigprocmask - examine and change blocked signals * @how: whether to add, remove, or set signals * @set: signals to add or remove (if non-null) * @oset: previous value of signal mask if non-null * * Some platforms have their own version with special arguments; * others support only sys_rt_sigprocmask. */ SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, set, old_sigset_t __user *, oset) { int error; old_sigset_t old_set, new_set; if (set) { error = -EFAULT; if (copy_from_user(&new_set, set, sizeof(*set))) goto out; new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP)); spin_lock_irq(¤t->sighand->siglock); old_set = current->blocked.sig[0]; error = 0; switch (how) { default: error = -EINVAL; break; case SIG_BLOCK: sigaddsetmask(¤t->blocked, new_set); break; case SIG_UNBLOCK: sigdelsetmask(¤t->blocked, new_set); break; case SIG_SETMASK: current->blocked.sig[0] = new_set; break; } recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); if (error) goto out; if (oset) goto set_old; } else if (oset) { old_set = current->blocked.sig[0]; set_old: error = -EFAULT; if (copy_to_user(oset, &old_set, sizeof(*oset))) goto out; } error = 0; out: return error; } #endif /* __ARCH_WANT_SYS_SIGPROCMASK */ #ifdef __ARCH_WANT_SYS_RT_SIGACTION /** * sys_rt_sigaction - alter an action taken by a process * @sig: signal to be sent * @act: the thread group ID of the thread * @oact: the PID of the thread * @sigsetsize: size of sigset_t type */ SYSCALL_DEFINE4(rt_sigaction, int, sig, const struct sigaction __user *, act, struct sigaction __user *, oact, size_t, sigsetsize) { struct k_sigaction new_sa, old_sa; int ret = -EINVAL; /* XXX: Don't preclude handling different sized sigset_t's. */ if (sigsetsize != sizeof(sigset_t)) goto out; if (act) { if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa))) return -EFAULT; } ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL); if (!ret && oact) { if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa))) return -EFAULT; } out: return ret; } #endif /* __ARCH_WANT_SYS_RT_SIGACTION */ #ifdef __ARCH_WANT_SYS_SGETMASK /* * For backwards compatibility. Functionality superseded by sigprocmask. */ SYSCALL_DEFINE0(sgetmask) { /* SMP safe */ return current->blocked.sig[0]; } SYSCALL_DEFINE1(ssetmask, int, newmask) { int old; spin_lock_irq(¤t->sighand->siglock); old = current->blocked.sig[0]; siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)| sigmask(SIGSTOP))); recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); return old; } #endif /* __ARCH_WANT_SGETMASK */ #ifdef __ARCH_WANT_SYS_SIGNAL /* * For backwards compatibility. Functionality superseded by sigaction. */ SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler) { struct k_sigaction new_sa, old_sa; int ret; new_sa.sa.sa_handler = handler; new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK; sigemptyset(&new_sa.sa.sa_mask); ret = do_sigaction(sig, &new_sa, &old_sa); return ret ? ret : (unsigned long)old_sa.sa.sa_handler; } #endif /* __ARCH_WANT_SYS_SIGNAL */ #ifdef __ARCH_WANT_SYS_PAUSE SYSCALL_DEFINE0(pause) { current->state = TASK_INTERRUPTIBLE; schedule(); return -ERESTARTNOHAND; } #endif #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND /** * sys_rt_sigsuspend - replace the signal mask for a value with the * @unewset value until a signal is received * @unewset: new signal mask value * @sigsetsize: size of sigset_t type */ SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize) { sigset_t newset; /* XXX: Don't preclude handling different sized sigset_t's. */ if (sigsetsize != sizeof(sigset_t)) return -EINVAL; if (copy_from_user(&newset, unewset, sizeof(newset))) return -EFAULT; sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP)); spin_lock_irq(¤t->sighand->siglock); current->saved_sigmask = current->blocked; current->blocked = newset; recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); current->state = TASK_INTERRUPTIBLE; schedule(); set_restore_sigmask(); return -ERESTARTNOHAND; } #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */ __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma) { return NULL; } void __init signals_init(void) { sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC); } #ifdef CONFIG_KGDB_KDB #include /* * kdb_send_sig_info - Allows kdb to send signals without exposing * signal internals. This function checks if the required locks are * available before calling the main signal code, to avoid kdb * deadlocks. */ void kdb_send_sig_info(struct task_struct *t, struct siginfo *info) { static struct task_struct *kdb_prev_t; int sig, new_t; if (!spin_trylock(&t->sighand->siglock)) { kdb_printf("Can't do kill command now.\n" "The sigmask lock is held somewhere else in " "kernel, try again later\n"); return; } spin_unlock(&t->sighand->siglock); new_t = kdb_prev_t != t; kdb_prev_t = t; if (t->state != TASK_RUNNING && new_t) { kdb_printf("Process is not RUNNING, sending a signal from " "kdb risks deadlock\n" "on the run queue locks. " "The signal has _not_ been sent.\n" "Reissue the kill command if you want to risk " "the deadlock.\n"); return; } sig = info->si_signo; if (send_sig_info(sig, info, t)) kdb_printf("Fail to deliver Signal %d to process %d.\n", sig, t->pid); else kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid); } #endif /* CONFIG_KGDB_KDB */