| /* |
| * 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/module.h> |
| #include <linux/init.h> |
| #include <linux/sched.h> |
| #include <linux/fs.h> |
| #include <linux/tty.h> |
| #include <linux/binfmts.h> |
| #include <linux/security.h> |
| #include <linux/syscalls.h> |
| #include <linux/ptrace.h> |
| #include <linux/signal.h> |
| #include <linux/signalfd.h> |
| #include <linux/tracehook.h> |
| #include <linux/capability.h> |
| #include <linux/freezer.h> |
| #include <linux/pid_namespace.h> |
| #include <linux/nsproxy.h> |
| #include <trace/events/sched.h> |
| |
| #include <asm/param.h> |
| #include <asm/uaccess.h> |
| #include <asm/unistd.h> |
| #include <asm/siginfo.h> |
| #include "audit.h" /* audit_signal_info() */ |
| |
| /* |
| * SLAB caches for signal bits. |
| */ |
| |
| static struct kmem_cache *sigqueue_cachep; |
| |
| 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. */ |
| |
| 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; |
| switch (_NSIG_WORDS) { |
| default: |
| for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m) |
| if ((x = *s &~ *m) != 0) { |
| sig = ffz(~x) + i*_NSIG_BPW + 1; |
| break; |
| } |
| break; |
| |
| case 2: if ((x = s[0] &~ m[0]) != 0) |
| sig = 1; |
| else if ((x = s[1] &~ m[1]) != 0) |
| sig = _NSIG_BPW + 1; |
| else |
| break; |
| sig += ffz(~x); |
| break; |
| |
| case 1: if ((x = *s &~ *m) != 0) |
| sig = ffz(~x) + 1; |
| break; |
| } |
| |
| return sig; |
| } |
| |
| /* |
| * allocate a new signal queue record |
| * - this may be called without locks if and only if t == current, otherwise an |
| * appopriate lock must be held to stop the target task from exiting |
| */ |
| static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags, |
| int override_rlimit) |
| { |
| struct sigqueue *q = NULL; |
| struct user_struct *user; |
| |
| /* |
| * We won't get problems with the target's UID changing under us |
| * because changing it requires RCU be used, and if t != current, the |
| * caller must be holding the RCU readlock (by way of a spinlock) and |
| * we use RCU protection here |
| */ |
| user = get_uid(__task_cred(t)->user); |
| atomic_inc(&user->sigpending); |
| if (override_rlimit || |
| atomic_read(&user->sigpending) <= |
| t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur) |
| q = kmem_cache_alloc(sigqueue_cachep, flags); |
| 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 = 0; |
| 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; |
| } |
| |
| /* |
| * Bad permissions for sending the signal |
| * - the caller must hold at least the RCU read lock |
| */ |
| static int check_kill_permission(int sig, struct siginfo *info, |
| struct task_struct *t) |
| { |
| const struct cred *cred = current_cred(), *tcred; |
| struct pid *sid; |
| int error; |
| |
| if (!valid_signal(sig)) |
| return -EINVAL; |
| |
| if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info))) |
| return 0; |
| |
| error = audit_signal_info(sig, t); /* Let audit system see the signal */ |
| if (error) |
| return error; |
| |
| tcred = __task_cred(t); |
| if ((cred->euid ^ tcred->suid) && |
| (cred->euid ^ tcred->uid) && |
| (cred->uid ^ tcred->suid) && |
| (cred->uid ^ tcred->uid) && |
| !capable(CAP_KILL)) { |
| 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_sched_signal_send(sig, 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(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(). |
| */ |
| return -EAGAIN; |
| } |
| |
| 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 |
| if (!is_si_special(info) && SI_FROMUSER(info) && |
| task_pid_nr_ns(current, task_active_pid_ns(t)) <= 0) |
| from_ancestor_ns = 1; |
| #endif |
| |
| return __send_signal(sig, info, t, group, from_ancestor_ns); |
| } |
| |
| int print_fatal_signals; |
| |
| 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; |
| } |
| |
| void |
| force_sig_specific(int sig, struct task_struct *t) |
| { |
| force_sig_info(sig, SEND_SIG_FORCED, t); |
| } |
| |
| /* |
| * Nuke all other threads in the group. |
| */ |
| void zap_other_threads(struct task_struct *p) |
| { |
| struct task_struct *t; |
| |
| p->signal->group_stop_count = 0; |
| |
| for (t = next_thread(p); t != p; t = next_thread(t)) { |
| /* |
| * Don't bother with already dead threads |
| */ |
| if (t->exit_state) |
| continue; |
| |
| /* SIGKILL will be handled before any pending SIGSTOP */ |
| sigaddset(&t->pending.signal, SIGKILL); |
| signal_wake_up(t, 1); |
| } |
| } |
| |
| 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 |
| * - the caller must hold the RCU read lock at least |
| */ |
| int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p) |
| { |
| int ret = check_kill_permission(sig, info, p); |
| |
| 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; |
| |
| if (!valid_signal(sig)) |
| return ret; |
| |
| read_lock(&tasklist_lock); |
| p = pid_task(pid, PIDTYPE_PID); |
| if (!p) { |
| ret = -ESRCH; |
| goto out_unlock; |
| } |
| pcred = __task_cred(p); |
| if ((info == SEND_SIG_NOINFO || |
| (!is_si_special(info) && 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 && p->sighand) { |
| unsigned long flags; |
| spin_lock_irqsave(&p->sighand->siglock, flags); |
| ret = __send_signal(sig, info, p, 1, 0); |
| spin_unlock_irqrestore(&p->sighand->siglock, flags); |
| } |
| out_unlock: |
| read_unlock(&tasklist_lock); |
| 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; |
| |
| if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0))) |
| 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() abot the following 3 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 nonzero 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) |
| { |
| 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 nonzero 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; |
| |
| if (unlikely(signal->group_stop_count > 0) && |
| do_signal_stop(0)) |
| goto relock; |
| |
| /* |
| * 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 { |
| 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]; |
| } |
| |
| 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. |
| */ |
| |
| 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; |
| } |
| |
| 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; |
| } |
| |
| 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 |
| 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 |
| |
| 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; |
| } |
| |
| 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); |
| } |
| |
| /* |
| * 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); |
| } |
| |
| 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(), which adds source info. */ |
| if (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(), which adds source info. */ |
| if (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 |
| |
| SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set) |
| { |
| return do_sigpending(set, sizeof(*set)); |
| } |
| |
| #endif |
| |
| #ifdef __ARCH_WANT_SYS_SIGPROCMASK |
| /* 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 |
| 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 |
| 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); |
| } |