diff options
Diffstat (limited to 'kernel/signal.c')
| -rw-r--r-- | kernel/signal.c | 4083 |
1 files changed, 4083 insertions, 0 deletions
diff --git a/kernel/signal.c b/kernel/signal.c new file mode 100644 index 000000000..4cc3f3ba1 --- /dev/null +++ b/kernel/signal.c @@ -0,0 +1,4083 @@ +/* + * linux/kernel/signal.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + * + * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson + * + * 2003-06-02 Jim Houston - Concurrent Computer Corp. + * Changes to use preallocated sigqueue structures + * to allow signals to be sent reliably. + */ + +#include <linux/slab.h> +#include <linux/export.h> +#include <linux/init.h> +#include <linux/sched/mm.h> +#include <linux/sched/user.h> +#include <linux/sched/debug.h> +#include <linux/sched/task.h> +#include <linux/sched/task_stack.h> +#include <linux/sched/cputime.h> +#include <linux/fs.h> +#include <linux/tty.h> +#include <linux/binfmts.h> +#include <linux/coredump.h> +#include <linux/security.h> +#include <linux/syscalls.h> +#include <linux/ptrace.h> +#include <linux/signal.h> +#include <linux/signalfd.h> +#include <linux/ratelimit.h> +#include <linux/tracehook.h> +#include <linux/capability.h> +#include <linux/freezer.h> +#include <linux/pid_namespace.h> +#include <linux/nsproxy.h> +#include <linux/user_namespace.h> +#include <linux/uprobes.h> +#include <linux/compat.h> +#include <linux/cn_proc.h> +#include <linux/compiler.h> +#include <linux/posix-timers.h> +#include <linux/livepatch.h> + +#define CREATE_TRACE_POINTS +#include <trace/events/signal.h> + +#include <asm/param.h> +#include <linux/uaccess.h> +#include <asm/unistd.h> +#include <asm/siginfo.h> +#include <asm/cacheflush.h> +#include "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 inline bool sig_handler_ignored(void __user *handler, int sig) +{ + /* Is it explicitly or implicitly ignored? */ + return handler == SIG_IGN || + (handler == SIG_DFL && sig_kernel_ignore(sig)); +} + +static bool sig_task_ignored(struct task_struct *t, int sig, bool force) +{ + void __user *handler; + + handler = sig_handler(t, sig); + + /* SIGKILL and SIGSTOP may not be sent to the global init */ + if (unlikely(is_global_init(t) && sig_kernel_only(sig))) + return true; + + if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) && + handler == SIG_DFL && !(force && sig_kernel_only(sig))) + return true; + + /* Only allow kernel generated signals to this kthread */ + if (unlikely((t->flags & PF_KTHREAD) && + (handler == SIG_KTHREAD_KERNEL) && !force)) + return true; + + return sig_handler_ignored(handler, sig); +} + +static bool sig_ignored(struct task_struct *t, int sig, bool force) +{ + /* + * Blocked signals are never ignored, since the + * signal handler may change by the time it is + * unblocked. + */ + if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig)) + return false; + + /* + * Tracers may want to know about even ignored signal unless it + * is SIGKILL which can't be reported anyway but can be ignored + * by SIGNAL_UNKILLABLE task. + */ + if (t->ptrace && sig != SIGKILL) + return false; + + return sig_task_ignored(t, sig, force); +} + +/* + * Re-calculate pending state from the set of locally pending + * signals, globally pending signals, and blocked signals. + */ +static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked) +{ + unsigned long ready; + long i; + + switch (_NSIG_WORDS) { + default: + for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;) + ready |= signal->sig[i] &~ blocked->sig[i]; + break; + + case 4: ready = signal->sig[3] &~ blocked->sig[3]; + ready |= signal->sig[2] &~ blocked->sig[2]; + ready |= signal->sig[1] &~ blocked->sig[1]; + ready |= signal->sig[0] &~ blocked->sig[0]; + break; + + case 2: ready = signal->sig[1] &~ blocked->sig[1]; + ready |= signal->sig[0] &~ blocked->sig[0]; + break; + + case 1: ready = signal->sig[0] &~ blocked->sig[0]; + } + return ready != 0; +} + +#define PENDING(p,b) has_pending_signals(&(p)->signal, (b)) + +static bool recalc_sigpending_tsk(struct task_struct *t) +{ + if ((t->jobctl & JOBCTL_PENDING_MASK) || + PENDING(&t->pending, &t->blocked) || + PENDING(&t->signal->shared_pending, &t->blocked)) { + set_tsk_thread_flag(t, TIF_SIGPENDING); + return true; + } + + /* + * We must never clear the flag in another thread, or in current + * when it's possible the current syscall is returning -ERESTART*. + * So we don't clear it here, and only callers who know they should do. + */ + return false; +} + +/* + * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up. + * This is superfluous when called on current, the wakeup is a harmless no-op. + */ +void recalc_sigpending_and_wake(struct task_struct *t) +{ + if (recalc_sigpending_tsk(t)) + signal_wake_up(t, 0); +} + +void recalc_sigpending(void) +{ + if (!recalc_sigpending_tsk(current) && !freezing(current) && + !klp_patch_pending(current)) + clear_thread_flag(TIF_SIGPENDING); + +} + +void calculate_sigpending(void) +{ + /* Have any signals or users of TIF_SIGPENDING been delayed + * until after fork? + */ + spin_lock_irq(¤t->sighand->siglock); + set_tsk_thread_flag(current, TIF_SIGPENDING); + recalc_sigpending(); + spin_unlock_irq(¤t->sighand->siglock); +} + +/* Given the mask, find the first available signal that should be serviced. */ + +#define SYNCHRONOUS_MASK \ + (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \ + sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS)) + +int next_signal(struct sigpending *pending, sigset_t *mask) +{ + unsigned long i, *s, *m, x; + int sig = 0; + + s = pending->signal.sig; + m = mask->sig; + + /* + * Handle the first word specially: it contains the + * synchronous signals that need to be dequeued first. + */ + x = *s &~ *m; + if (x) { + if (x & SYNCHRONOUS_MASK) + x &= SYNCHRONOUS_MASK; + sig = ffz(~x) + 1; + return sig; + } + + switch (_NSIG_WORDS) { + default: + for (i = 1; i < _NSIG_WORDS; ++i) { + x = *++s &~ *++m; + if (!x) + continue; + sig = ffz(~x) + i*_NSIG_BPW + 1; + break; + } + break; + + case 2: + x = s[1] &~ m[1]; + if (!x) + break; + sig = ffz(~x) + _NSIG_BPW + 1; + break; + + case 1: + /* Nothing to do */ + break; + } + + return sig; +} + +static inline void print_dropped_signal(int sig) +{ + static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10); + + if (!print_fatal_signals) + return; + + if (!__ratelimit(&ratelimit_state)) + return; + + pr_info("%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n", + current->comm, current->pid, sig); +} + +/** + * task_set_jobctl_pending - set jobctl pending bits + * @task: target task + * @mask: pending bits to set + * + * Clear @mask from @task->jobctl. @mask must be subset of + * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK | + * %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is + * cleared. If @task is already being killed or exiting, this function + * becomes noop. + * + * CONTEXT: + * Must be called with @task->sighand->siglock held. + * + * RETURNS: + * %true if @mask is set, %false if made noop because @task was dying. + */ +bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask) +{ + BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME | + JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING)); + BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK)); + + if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING))) + return false; + + if (mask & JOBCTL_STOP_SIGMASK) + task->jobctl &= ~JOBCTL_STOP_SIGMASK; + + task->jobctl |= mask; + return true; +} + +/** + * task_clear_jobctl_trapping - clear jobctl trapping bit + * @task: target task + * + * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED. + * Clear it and wake up the ptracer. Note that we don't need any further + * locking. @task->siglock guarantees that @task->parent points to the + * ptracer. + * + * CONTEXT: + * Must be called with @task->sighand->siglock held. + */ +void task_clear_jobctl_trapping(struct task_struct *task) +{ + if (unlikely(task->jobctl & JOBCTL_TRAPPING)) { + task->jobctl &= ~JOBCTL_TRAPPING; + smp_mb(); /* advised by wake_up_bit() */ + wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT); + } +} + +/** + * task_clear_jobctl_pending - clear jobctl pending bits + * @task: target task + * @mask: pending bits to clear + * + * Clear @mask from @task->jobctl. @mask must be subset of + * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other + * STOP bits are cleared together. + * + * If clearing of @mask leaves no stop or trap pending, this function calls + * task_clear_jobctl_trapping(). + * + * CONTEXT: + * Must be called with @task->sighand->siglock held. + */ +void task_clear_jobctl_pending(struct task_struct *task, unsigned long mask) +{ + BUG_ON(mask & ~JOBCTL_PENDING_MASK); + + if (mask & JOBCTL_STOP_PENDING) + mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED; + + task->jobctl &= ~mask; + + if (!(task->jobctl & JOBCTL_PENDING_MASK)) + task_clear_jobctl_trapping(task); +} + +/** + * task_participate_group_stop - participate in a group stop + * @task: task participating in a group stop + * + * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop. + * Group stop states are cleared and the group stop count is consumed if + * %JOBCTL_STOP_CONSUME was set. If the consumption completes the group + * stop, the appropriate %SIGNAL_* flags are set. + * + * CONTEXT: + * Must be called with @task->sighand->siglock held. + * + * RETURNS: + * %true if group stop completion should be notified to the parent, %false + * otherwise. + */ +static bool task_participate_group_stop(struct task_struct *task) +{ + struct signal_struct *sig = task->signal; + bool consume = task->jobctl & JOBCTL_STOP_CONSUME; + + WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING)); + + task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING); + + if (!consume) + return false; + + if (!WARN_ON_ONCE(sig->group_stop_count == 0)) + sig->group_stop_count--; + + /* + * Tell the caller to notify completion iff we are entering into a + * fresh group stop. Read comment in do_signal_stop() for details. + */ + if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) { + signal_set_stop_flags(sig, SIGNAL_STOP_STOPPED); + return true; + } + return false; +} + +void task_join_group_stop(struct task_struct *task) +{ + unsigned long mask = current->jobctl & JOBCTL_STOP_SIGMASK; + struct signal_struct *sig = current->signal; + + if (sig->group_stop_count) { + sig->group_stop_count++; + mask |= JOBCTL_STOP_CONSUME; + } else if (!(sig->flags & SIGNAL_STOP_STOPPED)) + return; + + /* Have the new thread join an on-going signal group stop */ + task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING); +} + +/* + * allocate a new signal queue record + * - this may be called without locks if and only if t == current, otherwise an + * appropriate lock must be held to stop the target task from exiting + */ +static struct sigqueue * +__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit) +{ + struct sigqueue *q = NULL; + struct user_struct *user; + int sigpending; + + /* + * Protect access to @t credentials. This can go away when all + * callers hold rcu read lock. + * + * NOTE! A pending signal will hold on to the user refcount, + * and we get/put the refcount only when the sigpending count + * changes from/to zero. + */ + rcu_read_lock(); + user = __task_cred(t)->user; + sigpending = atomic_inc_return(&user->sigpending); + if (sigpending == 1) + get_uid(user); + rcu_read_unlock(); + + if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) { + q = kmem_cache_alloc(sigqueue_cachep, flags); + } else { + print_dropped_signal(sig); + } + + if (unlikely(q == NULL)) { + if (atomic_dec_and_test(&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; + if (atomic_dec_and_test(&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 this kthread. + */ +void flush_signals(struct task_struct *t) +{ + unsigned long flags; + + spin_lock_irqsave(&t->sighand->siglock, flags); + clear_tsk_thread_flag(t, TIF_SIGPENDING); + flush_sigqueue(&t->pending); + flush_sigqueue(&t->signal->shared_pending); + spin_unlock_irqrestore(&t->sighand->siglock, flags); +} + +#ifdef CONFIG_POSIX_TIMERS +static void __flush_itimer_signals(struct sigpending *pending) +{ + sigset_t signal, retain; + struct sigqueue *q, *n; + + signal = pending->signal; + sigemptyset(&retain); + + list_for_each_entry_safe(q, n, &pending->list, list) { + int sig = q->info.si_signo; + + if (likely(q->info.si_code != SI_TIMER)) { + sigaddset(&retain, sig); + } else { + sigdelset(&signal, sig); + list_del_init(&q->list); + __sigqueue_free(q); + } + } + + sigorsets(&pending->signal, &signal, &retain); +} + +void flush_itimer_signals(void) +{ + struct task_struct *tsk = current; + unsigned long flags; + + spin_lock_irqsave(&tsk->sighand->siglock, flags); + __flush_itimer_signals(&tsk->pending); + __flush_itimer_signals(&tsk->signal->shared_pending); + spin_unlock_irqrestore(&tsk->sighand->siglock, flags); +} +#endif + +void ignore_signals(struct task_struct *t) +{ + int i; + + for (i = 0; i < _NSIG; ++i) + t->sighand->action[i].sa.sa_handler = SIG_IGN; + + flush_signals(t); +} + +/* + * Flush all handlers for a task. + */ + +void +flush_signal_handlers(struct task_struct *t, int force_default) +{ + int i; + struct k_sigaction *ka = &t->sighand->action[0]; + for (i = _NSIG ; i != 0 ; i--) { + if (force_default || ka->sa.sa_handler != SIG_IGN) + ka->sa.sa_handler = SIG_DFL; + ka->sa.sa_flags = 0; +#ifdef __ARCH_HAS_SA_RESTORER + ka->sa.sa_restorer = NULL; +#endif + sigemptyset(&ka->sa.sa_mask); + ka++; + } +} + +bool unhandled_signal(struct task_struct *tsk, int sig) +{ + void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler; + if (is_global_init(tsk)) + return true; + + if (handler != SIG_IGN && handler != SIG_DFL) + return false; + + /* if ptraced, let the tracer determine */ + return !tsk->ptrace; +} + +static void collect_signal(int sig, struct sigpending *list, siginfo_t *info, + bool *resched_timer) +{ + struct sigqueue *q, *first = NULL; + + /* + * Collect the siginfo appropriate to this signal. Check if + * there is another siginfo for the same signal. + */ + list_for_each_entry(q, &list->list, list) { + if (q->info.si_signo == sig) { + if (first) + goto still_pending; + first = q; + } + } + + sigdelset(&list->signal, sig); + + if (first) { +still_pending: + list_del_init(&first->list); + copy_siginfo(info, &first->info); + + *resched_timer = + (first->flags & SIGQUEUE_PREALLOC) && + (info->si_code == SI_TIMER) && + (info->si_sys_private); + + __sigqueue_free(first); + } else { + /* + * Ok, it wasn't in the queue. This must be + * a fast-pathed signal or we must have been + * out of queue space. So zero out the info. + */ + clear_siginfo(info); + info->si_signo = sig; + info->si_errno = 0; + info->si_code = SI_USER; + info->si_pid = 0; + info->si_uid = 0; + } +} + +static int __dequeue_signal(struct sigpending *pending, sigset_t *mask, + siginfo_t *info, bool *resched_timer) +{ + int sig = next_signal(pending, mask); + + if (sig) + collect_signal(sig, pending, info, resched_timer); + return sig; +} + +/* + * Dequeue a signal and return the element to the caller, which is + * expected to free it. + * + * All callers have to hold the siglock. + */ +int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info) +{ + bool resched_timer = false; + int signr; + + /* We only dequeue private signals from ourselves, we don't let + * signalfd steal them + */ + signr = __dequeue_signal(&tsk->pending, mask, info, &resched_timer); + if (!signr) { + signr = __dequeue_signal(&tsk->signal->shared_pending, + mask, info, &resched_timer); +#ifdef CONFIG_POSIX_TIMERS + /* + * itimer signal ? + * + * itimers are process shared and we restart periodic + * itimers in the signal delivery path to prevent DoS + * attacks in the high resolution timer case. This is + * compliant with the old way of self-restarting + * itimers, as the SIGALRM is a legacy signal and only + * queued once. Changing the restart behaviour to + * restart the timer in the signal dequeue path is + * reducing the timer noise on heavy loaded !highres + * systems too. + */ + if (unlikely(signr == SIGALRM)) { + struct hrtimer *tmr = &tsk->signal->real_timer; + + if (!hrtimer_is_queued(tmr) && + tsk->signal->it_real_incr != 0) { + hrtimer_forward(tmr, tmr->base->get_time(), + tsk->signal->it_real_incr); + hrtimer_restart(tmr); + } + } +#endif + } + + recalc_sigpending(); + if (!signr) + return 0; + + if (unlikely(sig_kernel_stop(signr))) { + /* + * Set a marker that we have dequeued a stop signal. Our + * caller might release the siglock and then the pending + * stop signal it is about to process is no longer in the + * pending bitmasks, but must still be cleared by a SIGCONT + * (and overruled by a SIGKILL). So those cases clear this + * shared flag after we've set it. Note that this flag may + * remain set after the signal we return is ignored or + * handled. That doesn't matter because its only purpose + * is to alert stop-signal processing code when another + * processor has come along and cleared the flag. + */ + current->jobctl |= JOBCTL_STOP_DEQUEUED; + } +#ifdef CONFIG_POSIX_TIMERS + if (resched_timer) { + /* + * Release the siglock to ensure proper locking order + * of timer locks outside of siglocks. Note, we leave + * irqs disabled here, since the posix-timers code is + * about to disable them again anyway. + */ + spin_unlock(&tsk->sighand->siglock); + posixtimer_rearm(info); + spin_lock(&tsk->sighand->siglock); + + /* Don't expose the si_sys_private value to userspace */ + info->si_sys_private = 0; + } +#endif + return signr; +} + +static int dequeue_synchronous_signal(siginfo_t *info) +{ + struct task_struct *tsk = current; + struct sigpending *pending = &tsk->pending; + struct sigqueue *q, *sync = NULL; + + /* + * Might a synchronous signal be in the queue? + */ + if (!((pending->signal.sig[0] & ~tsk->blocked.sig[0]) & SYNCHRONOUS_MASK)) + return 0; + + /* + * Return the first synchronous signal in the queue. + */ + list_for_each_entry(q, &pending->list, list) { + /* Synchronous signals have a postive si_code */ + if ((q->info.si_code > SI_USER) && + (sigmask(q->info.si_signo) & SYNCHRONOUS_MASK)) { + sync = q; + goto next; + } + } + return 0; +next: + /* + * Check if there is another siginfo for the same signal. + */ + list_for_each_entry_continue(q, &pending->list, list) { + if (q->info.si_signo == sync->info.si_signo) + goto still_pending; + } + + sigdelset(&pending->signal, sync->info.si_signo); + recalc_sigpending(); +still_pending: + list_del_init(&sync->list); + copy_siginfo(info, &sync->info); + __sigqueue_free(sync); + return info->si_signo; +} + +/* + * Tell a process that it has a new active signal.. + * + * NOTE! we rely on the previous spin_lock to + * lock interrupts for us! We can only be called with + * "siglock" held, and the local interrupt must + * have been disabled when that got acquired! + * + * No need to set need_resched since signal event passing + * goes through ->blocked + */ +void signal_wake_up_state(struct task_struct *t, unsigned int state) +{ + set_tsk_thread_flag(t, TIF_SIGPENDING); + /* + * TASK_WAKEKILL also means wake it up in the stopped/traced/killable + * case. We don't check t->state here because there is a race with it + * executing another processor and just now entering stopped state. + * By using wake_up_state, we ensure the process will wake up and + * handle its death signal. + */ + if (!wake_up_state(t, state | TASK_INTERRUPTIBLE)) + kick_process(t); +} + +/* + * Remove signals in mask from the pending set and queue. + * Returns 1 if any signals were found. + * + * All callers must be holding the siglock. + */ +static void flush_sigqueue_mask(sigset_t *mask, struct sigpending *s) +{ + struct sigqueue *q, *n; + sigset_t m; + + sigandsets(&m, mask, &s->signal); + if (sigisemptyset(&m)) + return; + + sigandnsets(&s->signal, &s->signal, mask); + list_for_each_entry_safe(q, n, &s->list, list) { + if (sigismember(mask, q->info.si_signo)) { + list_del_init(&q->list); + __sigqueue_free(q); + } + } +} + +static inline int is_si_special(const struct 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 bool kill_ok_by_cred(struct task_struct *t) +{ + const struct cred *cred = current_cred(); + const struct cred *tcred = __task_cred(t); + + return uid_eq(cred->euid, tcred->suid) || + uid_eq(cred->euid, tcred->uid) || + uid_eq(cred->uid, tcred->suid) || + uid_eq(cred->uid, tcred->uid) || + ns_capable(tcred->user_ns, CAP_KILL); +} + +/* + * Bad permissions for sending the signal + * - the caller must hold the RCU read lock + */ +static int check_kill_permission(int sig, struct 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, NULL); +} + +/** + * ptrace_trap_notify - schedule trap to notify ptracer + * @t: tracee wanting to notify tracer + * + * This function schedules sticky ptrace trap which is cleared on the next + * TRAP_STOP to notify ptracer of an event. @t must have been seized by + * ptracer. + * + * If @t is running, STOP trap will be taken. If trapped for STOP and + * ptracer is listening for events, tracee is woken up so that it can + * re-trap for the new event. If trapped otherwise, STOP trap will be + * eventually taken without returning to userland after the existing traps + * are finished by PTRACE_CONT. + * + * CONTEXT: + * Must be called with @task->sighand->siglock held. + */ +static void ptrace_trap_notify(struct task_struct *t) +{ + WARN_ON_ONCE(!(t->ptrace & PT_SEIZED)); + assert_spin_locked(&t->sighand->siglock); + + task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY); + ptrace_signal_wake_up(t, t->jobctl & JOBCTL_LISTENING); +} + +/* + * Handle magic process-wide effects of stop/continue signals. Unlike + * the signal actions, these happen immediately at signal-generation + * time regardless of blocking, ignoring, or handling. This does the + * actual continuing for SIGCONT, but not the actual stopping for stop + * signals. The process stop is done as a signal action for SIG_DFL. + * + * Returns true if the signal should be actually delivered, otherwise + * it should be dropped. + */ +static bool prepare_signal(int sig, struct task_struct *p, bool force) +{ + struct signal_struct *signal = p->signal; + struct task_struct *t; + sigset_t flush; + + if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) { + if (!(signal->flags & SIGNAL_GROUP_EXIT)) + return sig == SIGKILL; + /* + * 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. + */ + siginitset(&flush, sigmask(SIGCONT)); + flush_sigqueue_mask(&flush, &signal->shared_pending); + for_each_thread(p, t) + flush_sigqueue_mask(&flush, &t->pending); + } else if (sig == SIGCONT) { + unsigned int why; + /* + * Remove all stop signals from all queues, wake all threads. + */ + siginitset(&flush, SIG_KERNEL_STOP_MASK); + flush_sigqueue_mask(&flush, &signal->shared_pending); + for_each_thread(p, t) { + flush_sigqueue_mask(&flush, &t->pending); + task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING); + if (likely(!(t->ptrace & PT_SEIZED))) + wake_up_state(t, __TASK_STOPPED); + else + ptrace_trap_notify(t); + } + + /* + * Notify the parent with CLD_CONTINUED if we were stopped. + * + * If we were in the middle of a group stop, we pretend it + * was already finished, and then continued. Since SIGCHLD + * doesn't queue we report only CLD_STOPPED, as if the next + * CLD_CONTINUED was dropped. + */ + why = 0; + if (signal->flags & SIGNAL_STOP_STOPPED) + why |= SIGNAL_CLD_CONTINUED; + else if (signal->group_stop_count) + why |= SIGNAL_CLD_STOPPED; + + if (why) { + /* + * The first thread which returns from do_signal_stop() + * will take ->siglock, notice SIGNAL_CLD_MASK, and + * notify its parent. See get_signal_to_deliver(). + */ + signal_set_stop_flags(signal, why | SIGNAL_STOP_CONTINUED); + signal->group_stop_count = 0; + signal->group_exit_code = 0; + } + } + + return !sig_ignored(p, sig, force); +} + +/* + * Test if P wants to take SIG. After we've checked all threads with this, + * it's equivalent to finding no threads not blocking SIG. Any threads not + * blocking SIG were ruled out because they are not running and already + * have pending signals. Such threads will dequeue from the shared queue + * as soon as they're available, so putting the signal on the shared queue + * will be equivalent to sending it to one such thread. + */ +static inline bool wants_signal(int sig, struct task_struct *p) +{ + if (sigismember(&p->blocked, sig)) + return false; + + if (p->flags & PF_EXITING) + return false; + + if (sig == SIGKILL) + return true; + + if (task_is_stopped_or_traced(p)) + return false; + + return task_curr(p) || !signal_pending(p); +} + +static void complete_signal(int sig, struct task_struct *p, enum pid_type type) +{ + struct signal_struct *signal = p->signal; + struct task_struct *t; + + /* + * Now find a thread we can wake up to take the signal off the queue. + * + * If the main thread wants the signal, it gets first crack. + * Probably the least surprising to the average bear. + */ + if (wants_signal(sig, p)) + t = p; + else if ((type == PIDTYPE_PID) || thread_group_empty(p)) + /* + * There is just one thread and it does not need to be woken. + * It will dequeue unblocked signals before it runs again. + */ + return; + else { + /* + * Otherwise try to find a suitable thread. + */ + t = signal->curr_target; + while (!wants_signal(sig, t)) { + t = next_thread(t); + if (t == signal->curr_target) + /* + * No thread needs to be woken. + * Any eligible threads will see + * the signal in the queue soon. + */ + return; + } + signal->curr_target = t; + } + + /* + * Found a killable thread. If the signal will be fatal, + * then start taking the whole group down immediately. + */ + if (sig_fatal(p, sig) && + !(signal->flags & SIGNAL_GROUP_EXIT) && + !sigismember(&t->real_blocked, sig) && + (sig == SIGKILL || !p->ptrace)) { + /* + * This signal will be fatal to the whole group. + */ + if (!sig_kernel_coredump(sig)) { + /* + * Start a group exit and wake everybody up. + * This way we don't have other threads + * running and doing things after a slower + * thread has the fatal signal pending. + */ + signal->flags = SIGNAL_GROUP_EXIT; + signal->group_exit_code = sig; + signal->group_stop_count = 0; + t = p; + do { + task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); + 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 bool legacy_queue(struct sigpending *signals, int sig) +{ + return (sig < SIGRTMIN) && sigismember(&signals->signal, sig); +} + +#ifdef CONFIG_USER_NS +static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t) +{ + if (current_user_ns() == task_cred_xxx(t, user_ns)) + return; + + if (SI_FROMKERNEL(info)) + return; + + rcu_read_lock(); + info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns), + make_kuid(current_user_ns(), info->si_uid)); + rcu_read_unlock(); +} +#else +static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t) +{ + return; +} +#endif + +static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, + enum pid_type type, int from_ancestor_ns) +{ + struct sigpending *pending; + struct sigqueue *q; + int override_rlimit; + int ret = 0, result; + + assert_spin_locked(&t->sighand->siglock); + + result = TRACE_SIGNAL_IGNORED; + if (!prepare_signal(sig, t, + from_ancestor_ns || (info == SEND_SIG_PRIV) || (info == SEND_SIG_FORCED))) + goto ret; + + pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending; + /* + * Short-circuit ignored signals and support queuing + * exactly one non-rt signal, so that we can get more + * detailed information about the cause of the signal. + */ + result = TRACE_SIGNAL_ALREADY_PENDING; + if (legacy_queue(pending, sig)) + goto ret; + + result = TRACE_SIGNAL_DELIVERED; + /* + * 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, override_rlimit); + if (q) { + list_add_tail(&q->list, &pending->list); + switch ((unsigned long) info) { + case (unsigned long) SEND_SIG_NOINFO: + clear_siginfo(&q->info); + q->info.si_signo = sig; + q->info.si_errno = 0; + q->info.si_code = SI_USER; + q->info.si_pid = task_tgid_nr_ns(current, + task_active_pid_ns(t)); + q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid()); + break; + case (unsigned long) SEND_SIG_PRIV: + clear_siginfo(&q->info); + q->info.si_signo = sig; + q->info.si_errno = 0; + q->info.si_code = SI_KERNEL; + q->info.si_pid = 0; + q->info.si_uid = 0; + break; + default: + copy_siginfo(&q->info, info); + if (from_ancestor_ns) + q->info.si_pid = 0; + break; + } + + userns_fixup_signal_uid(&q->info, t); + + } 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(). + */ + result = TRACE_SIGNAL_OVERFLOW_FAIL; + ret = -EAGAIN; + goto ret; + } else { + /* + * This is a silent loss of information. We still + * send the signal, but the *info bits are lost. + */ + result = TRACE_SIGNAL_LOSE_INFO; + } + } + +out_set: + signalfd_notify(t, sig); + sigaddset(&pending->signal, sig); + + /* Let multiprocess signals appear after on-going forks */ + if (type > PIDTYPE_TGID) { + struct multiprocess_signals *delayed; + hlist_for_each_entry(delayed, &t->signal->multiprocess, node) { + sigset_t *signal = &delayed->signal; + /* Can't queue both a stop and a continue signal */ + if (sig == SIGCONT) + sigdelsetmask(signal, SIG_KERNEL_STOP_MASK); + else if (sig_kernel_stop(sig)) + sigdelset(signal, SIGCONT); + sigaddset(signal, sig); + } + } + + complete_signal(sig, t, type); +ret: + trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result); + return ret; +} + +static int send_signal(int sig, struct siginfo *info, struct task_struct *t, + enum pid_type type) +{ + 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, type, from_ancestor_ns); +} + +static void print_fatal_signal(int signr) +{ + struct pt_regs *regs = signal_pt_regs(); + pr_info("potentially unexpected fatal signal %d.\n", signr); + +#if defined(__i386__) && !defined(__arch_um__) + pr_info("code at %08lx: ", regs->ip); + { + int i; + for (i = 0; i < 16; i++) { + unsigned char insn; + + if (get_user(insn, (unsigned char *)(regs->ip + i))) + break; + pr_cont("%02x ", insn); + } + } + pr_cont("\n"); +#endif + preempt_disable(); + show_regs(regs); + preempt_enable(); +} + +static int __init setup_print_fatal_signals(char *str) +{ + get_option (&str, &print_fatal_signals); + + return 1; +} + +__setup("print-fatal-signals=", setup_print_fatal_signals); + +int +__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p) +{ + return send_signal(sig, info, p, PIDTYPE_TGID); +} + +static int +specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t) +{ + return send_signal(sig, info, t, PIDTYPE_PID); +} + +int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p, + enum pid_type type) +{ + unsigned long flags; + int ret = -ESRCH; + + if (lock_task_sighand(p, &flags)) { + ret = send_signal(sig, info, p, type); + 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); + } + } + /* + * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect + * debugging to leave init killable. + */ + if (action->sa.sa_handler == SIG_DFL && !t->ptrace) + 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) { + task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); + count++; + + /* Don't bother with already dead threads */ + if (t->exit_state) + continue; + sigaddset(&t->pending.signal, SIGKILL); + signal_wake_up(t, 1); + } + + return count; +} + +struct sighand_struct *__lock_task_sighand(struct task_struct *tsk, + unsigned long *flags) +{ + struct sighand_struct *sighand; + + rcu_read_lock(); + for (;;) { + sighand = rcu_dereference(tsk->sighand); + if (unlikely(sighand == NULL)) + break; + + /* + * This sighand can be already freed and even reused, but + * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which + * initializes ->siglock: this slab can't go away, it has + * the same object type, ->siglock can't be reinitialized. + * + * We need to ensure that tsk->sighand is still the same + * after we take the lock, we can race with de_thread() or + * __exit_signal(). In the latter case the next iteration + * must see ->sighand == NULL. + */ + spin_lock_irqsave(&sighand->siglock, *flags); + if (likely(sighand == 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, + enum pid_type type) +{ + int ret; + + rcu_read_lock(); + ret = check_kill_permission(sig, info, p); + rcu_read_unlock(); + + if (!ret && sig) + ret = do_send_sig_info(sig, info, p, type); + + 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, PIDTYPE_PGID); + success |= !err; + retval = err; + } while_each_pid_task(pgrp, PIDTYPE_PGID, p); + return success ? 0 : retval; +} + +int kill_pid_info(int sig, struct siginfo *info, struct pid *pid) +{ + int error = -ESRCH; + struct task_struct *p; + + for (;;) { + rcu_read_lock(); + p = pid_task(pid, PIDTYPE_PID); + if (p) + error = group_send_sig_info(sig, info, p, PIDTYPE_TGID); + rcu_read_unlock(); + if (likely(!p || error != -ESRCH)) + return error; + + /* + * The task was unhashed in between, try again. If it + * is dead, pid_task() will return NULL, if we race with + * de_thread() it will find the new leader. + */ + } +} + +static int kill_proc_info(int sig, struct siginfo *info, pid_t pid) +{ + int error; + rcu_read_lock(); + error = kill_pid_info(sig, info, find_vpid(pid)); + rcu_read_unlock(); + return error; +} + +static inline bool kill_as_cred_perm(const struct cred *cred, + struct task_struct *target) +{ + const struct cred *pcred = __task_cred(target); + + return uid_eq(cred->euid, pcred->suid) || + uid_eq(cred->euid, pcred->uid) || + uid_eq(cred->uid, pcred->suid) || + uid_eq(cred->uid, pcred->uid); +} + +/* like kill_pid_info(), but doesn't use uid/euid of "current" */ +int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid, + const struct cred *cred) +{ + int ret = -EINVAL; + struct task_struct *p; + 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; + } + if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) { + ret = -EPERM; + goto out_unlock; + } + ret = security_task_kill(p, info, sig, cred); + if (ret) + goto out_unlock; + + if (sig) { + if (lock_task_sighand(p, &flags)) { + ret = __send_signal(sig, info, p, PIDTYPE_TGID, 0); + unlock_task_sighand(p, &flags); + } else + ret = -ESRCH; + } +out_unlock: + rcu_read_unlock(); + return ret; +} +EXPORT_SYMBOL_GPL(kill_pid_info_as_cred); + +/* + * 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; + } + + /* -INT_MIN is undefined. Exclude this case to avoid a UBSAN warning */ + if (pid == INT_MIN) + return -ESRCH; + + read_lock(&tasklist_lock); + if (pid != -1) { + ret = __kill_pgrp_info(sig, info, + pid ? find_vpid(-pid) : task_pgrp(current)); + } else { + int retval = 0, count = 0; + struct task_struct * p; + + for_each_process(p) { + if (task_pid_vnr(p) > 1 && + !same_thread_group(p, current)) { + int err = group_send_sig_info(sig, info, p, + PIDTYPE_MAX); + ++count; + if (err != -EPERM) + retval = err; + } + } + ret = count ? retval : -ESRCH; + } + read_unlock(&tasklist_lock); + + return ret; +} + +/* + * These are for backward compatibility with the rest of the kernel source. + */ + +int send_sig_info(int sig, struct siginfo *info, struct task_struct *p) +{ + /* + * Make sure legacy kernel users don't send in bad values + * (normal paths check this in check_kill_permission). + */ + if (!valid_signal(sig)) + return -EINVAL; + + return do_send_sig_info(sig, info, p, PIDTYPE_PID); +} + +#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.. + */ +void 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); +} + +int force_sig_fault(int sig, int code, void __user *addr + ___ARCH_SI_TRAPNO(int trapno) + ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr) + , struct task_struct *t) +{ + struct siginfo info; + + clear_siginfo(&info); + info.si_signo = sig; + info.si_errno = 0; + info.si_code = code; + info.si_addr = addr; +#ifdef __ARCH_SI_TRAPNO + info.si_trapno = trapno; +#endif +#ifdef __ia64__ + info.si_imm = imm; + info.si_flags = flags; + info.si_isr = isr; +#endif + return force_sig_info(info.si_signo, &info, t); +} + +int send_sig_fault(int sig, int code, void __user *addr + ___ARCH_SI_TRAPNO(int trapno) + ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr) + , struct task_struct *t) +{ + struct siginfo info; + + clear_siginfo(&info); + info.si_signo = sig; + info.si_errno = 0; + info.si_code = code; + info.si_addr = addr; +#ifdef __ARCH_SI_TRAPNO + info.si_trapno = trapno; +#endif +#ifdef __ia64__ + info.si_imm = imm; + info.si_flags = flags; + info.si_isr = isr; +#endif + return send_sig_info(info.si_signo, &info, t); +} + +int force_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t) +{ + struct siginfo info; + + WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR)); + clear_siginfo(&info); + info.si_signo = SIGBUS; + info.si_errno = 0; + info.si_code = code; + info.si_addr = addr; + info.si_addr_lsb = lsb; + return force_sig_info(info.si_signo, &info, t); +} + +int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t) +{ + struct siginfo info; + + WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR)); + clear_siginfo(&info); + info.si_signo = SIGBUS; + info.si_errno = 0; + info.si_code = code; + info.si_addr = addr; + info.si_addr_lsb = lsb; + return send_sig_info(info.si_signo, &info, t); +} +EXPORT_SYMBOL(send_sig_mceerr); + +int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper) +{ + struct siginfo info; + + clear_siginfo(&info); + info.si_signo = SIGSEGV; + info.si_errno = 0; + info.si_code = SEGV_BNDERR; + info.si_addr = addr; + info.si_lower = lower; + info.si_upper = upper; + return force_sig_info(info.si_signo, &info, current); +} + +#ifdef SEGV_PKUERR +int force_sig_pkuerr(void __user *addr, u32 pkey) +{ + struct siginfo info; + + clear_siginfo(&info); + info.si_signo = SIGSEGV; + info.si_errno = 0; + info.si_code = SEGV_PKUERR; + info.si_addr = addr; + info.si_pkey = pkey; + return force_sig_info(info.si_signo, &info, current); +} +#endif + +/* For the crazy architectures that include trap information in + * the errno field, instead of an actual errno value. + */ +int force_sig_ptrace_errno_trap(int errno, void __user *addr) +{ + struct siginfo info; + + clear_siginfo(&info); + info.si_signo = SIGTRAP; + info.si_errno = errno; + info.si_code = TRAP_HWBKPT; + info.si_addr = addr; + return force_sig_info(info.si_signo, &info, current); +} + +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 pid *pid, enum pid_type type) +{ + int sig = q->info.si_signo; + struct sigpending *pending; + struct task_struct *t; + unsigned long flags; + int ret, result; + + BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); + + ret = -1; + rcu_read_lock(); + t = pid_task(pid, type); + if (!t || !likely(lock_task_sighand(t, &flags))) + goto ret; + + ret = 1; /* the signal is ignored */ + result = TRACE_SIGNAL_IGNORED; + if (!prepare_signal(sig, t, false)) + goto out; + + ret = 0; + if (unlikely(!list_empty(&q->list))) { + /* + * If an SI_TIMER entry is already queue just increment + * the overrun count. + */ + BUG_ON(q->info.si_code != SI_TIMER); + q->info.si_overrun++; + result = TRACE_SIGNAL_ALREADY_PENDING; + goto out; + } + q->info.si_overrun = 0; + + signalfd_notify(t, sig); + pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending; + list_add_tail(&q->list, &pending->list); + sigaddset(&pending->signal, sig); + complete_signal(sig, t, type); + result = TRACE_SIGNAL_DELIVERED; +out: + trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result); + unlock_task_sighand(t, &flags); +ret: + rcu_read_unlock(); + return ret; +} + +/* + * Let a parent know about the death of a child. + * For a stopped/continued status change, use do_notify_parent_cldstop instead. + * + * Returns true if our parent ignored us and so we've switched to + * self-reaping. + */ +bool do_notify_parent(struct task_struct *tsk, int sig) +{ + struct siginfo info; + unsigned long flags; + struct sighand_struct *psig; + bool autoreap = false; + u64 utime, stime; + + BUG_ON(sig == -1); + + /* do_notify_parent_cldstop should have been called instead. */ + BUG_ON(task_is_stopped_or_traced(tsk)); + + BUG_ON(!tsk->ptrace && + (tsk->group_leader != tsk || !thread_group_empty(tsk))); + + if (sig != SIGCHLD) { + /* + * This is only possible if parent == real_parent. + * Check if it has changed security domain. + */ + if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id)) + sig = SIGCHLD; + } + + clear_siginfo(&info); + info.si_signo = sig; + info.si_errno = 0; + /* + * We are under tasklist_lock here so our parent is tied to + * us and cannot change. + * + * task_active_pid_ns will always return the same pid namespace + * until a task passes through release_task. + * + * write_lock() currently calls preempt_disable() which is the + * same as rcu_read_lock(), but according to Oleg, this is not + * correct to rely on this + */ + rcu_read_lock(); + info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(tsk->parent)); + info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns), + task_uid(tsk)); + rcu_read_unlock(); + + task_cputime(tsk, &utime, &stime); + info.si_utime = nsec_to_clock_t(utime + tsk->signal->utime); + info.si_stime = nsec_to_clock_t(stime + tsk->signal->stime); + + info.si_status = tsk->exit_code & 0x7f; + if (tsk->exit_code & 0x80) + info.si_code = CLD_DUMPED; + else if (tsk->exit_code & 0x7f) + info.si_code = CLD_KILLED; + else { + info.si_code = CLD_EXITED; + info.si_status = tsk->exit_code >> 8; + } + + psig = tsk->parent->sighand; + spin_lock_irqsave(&psig->siglock, flags); + if (!tsk->ptrace && sig == SIGCHLD && + (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN || + (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) { + /* + * We are exiting and our parent doesn't care. POSIX.1 + * defines special semantics for setting SIGCHLD to SIG_IGN + * or setting the SA_NOCLDWAIT flag: we should be reaped + * automatically and not left for our parent's wait4 call. + * Rather than having the parent do it as a magic kind of + * signal handler, we just set this to tell do_exit that we + * can be cleaned up without becoming a zombie. Note that + * we still call __wake_up_parent in this case, because a + * blocked sys_wait4 might now return -ECHILD. + * + * Whether we send SIGCHLD or not for SA_NOCLDWAIT + * is implementation-defined: we do (if you don't want + * it, just use SIG_IGN instead). + */ + autoreap = true; + if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) + sig = 0; + } + if (valid_signal(sig) && sig) + __group_send_sig_info(sig, &info, tsk->parent); + __wake_up_parent(tsk, tsk->parent); + spin_unlock_irqrestore(&psig->siglock, flags); + + return autoreap; +} + +/** + * do_notify_parent_cldstop - notify parent of stopped/continued state change + * @tsk: task reporting the state change + * @for_ptracer: the notification is for ptracer + * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report + * + * Notify @tsk's parent that the stopped/continued state has changed. If + * @for_ptracer is %false, @tsk's group leader notifies to its real parent. + * If %true, @tsk reports to @tsk->parent which should be the ptracer. + * + * CONTEXT: + * Must be called with tasklist_lock at least read locked. + */ +static void do_notify_parent_cldstop(struct task_struct *tsk, + bool for_ptracer, int why) +{ + struct siginfo info; + unsigned long flags; + struct task_struct *parent; + struct sighand_struct *sighand; + u64 utime, stime; + + if (for_ptracer) { + parent = tsk->parent; + } else { + tsk = tsk->group_leader; + parent = tsk->real_parent; + } + + clear_siginfo(&info); + info.si_signo = SIGCHLD; + info.si_errno = 0; + /* + * see comment in do_notify_parent() about the following 4 lines + */ + rcu_read_lock(); + info.si_pid = task_pid_nr_ns(tsk, task_active_pid_ns(parent)); + info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk)); + rcu_read_unlock(); + + task_cputime(tsk, &utime, &stime); + info.si_utime = nsec_to_clock_t(utime); + info.si_stime = nsec_to_clock_t(stime); + + info.si_code = why; + switch (why) { + case CLD_CONTINUED: + info.si_status = SIGCONT; + break; + case CLD_STOPPED: + info.si_status = tsk->signal->group_exit_code & 0x7f; + break; + case CLD_TRAPPED: + info.si_status = tsk->exit_code & 0x7f; + break; + default: + BUG(); + } + + sighand = parent->sighand; + spin_lock_irqsave(&sighand->siglock, flags); + if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN && + !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP)) + __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 bool may_ptrace_stop(void) +{ + if (!likely(current->ptrace)) + return false; + /* + * 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(). + * + * This is almost outdated, a task with the pending SIGKILL can't + * block in TASK_TRACED. But PTRACE_EVENT_EXIT can be reported + * after SIGKILL was already dequeued. + */ + if (unlikely(current->mm->core_state) && + unlikely(current->mm == current->parent->mm)) + return false; + + return true; +} + + +/* + * 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 why, int clear_code, siginfo_t *info) + __releases(¤t->sighand->siglock) + __acquires(¤t->sighand->siglock) +{ + bool gstop_done = false; + + 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. + */ + spin_unlock_irq(¤t->sighand->siglock); + arch_ptrace_stop(exit_code, info); + spin_lock_irq(¤t->sighand->siglock); + } + + /* + * schedule() will not sleep if there is a pending signal that + * can awaken the task. + */ + set_special_state(TASK_TRACED); + + /* + * We're committing to trapping. TRACED should be visible before + * TRAPPING is cleared; otherwise, the tracer might fail do_wait(). + * Also, transition to TRACED and updates to ->jobctl should be + * atomic with respect to siglock and should be done after the arch + * hook as siglock is released and regrabbed across it. + * + * TRACER TRACEE + * + * ptrace_attach() + * [L] wait_on_bit(JOBCTL_TRAPPING) [S] set_special_state(TRACED) + * do_wait() + * set_current_state() smp_wmb(); + * ptrace_do_wait() + * wait_task_stopped() + * task_stopped_code() + * [L] task_is_traced() [S] task_clear_jobctl_trapping(); + */ + smp_wmb(); + + current->last_siginfo = info; + current->exit_code = exit_code; + + /* + * If @why is CLD_STOPPED, we're trapping to participate in a group + * stop. Do the bookkeeping. Note that if SIGCONT was delievered + * across siglock relocks since INTERRUPT was scheduled, PENDING + * could be clear now. We act as if SIGCONT is received after + * TASK_TRACED is entered - ignore it. + */ + if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING)) + gstop_done = task_participate_group_stop(current); + + /* any trap clears pending STOP trap, STOP trap clears NOTIFY */ + task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP); + if (info && info->si_code >> 8 == PTRACE_EVENT_STOP) + task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY); + + /* entering a trap, clear TRAPPING */ + task_clear_jobctl_trapping(current); + + spin_unlock_irq(¤t->sighand->siglock); + read_lock(&tasklist_lock); + if (may_ptrace_stop()) { + /* + * Notify parents of the stop. + * + * While ptraced, there are two parents - the ptracer and + * the real_parent of the group_leader. The ptracer should + * know about every stop while the real parent is only + * interested in the completion of group stop. The states + * for the two don't interact with each other. Notify + * separately unless they're gonna be duplicates. + */ + do_notify_parent_cldstop(current, true, why); + if (gstop_done && ptrace_reparented(current)) + do_notify_parent_cldstop(current, false, why); + + /* + * Don't want to allow preemption here, because + * sys_ptrace() needs this task to be inactive. + * + * XXX: implement read_unlock_no_resched(). + */ + preempt_disable(); + read_unlock(&tasklist_lock); + preempt_enable_no_resched(); + freezable_schedule(); + } else { + /* + * By the time we got the lock, our tracer went away. + * Don't drop the lock yet, another tracer may come. + * + * If @gstop_done, the ptracer went away between group stop + * completion and here. During detach, it would have set + * JOBCTL_STOP_PENDING on us and we'll re-enter + * TASK_STOPPED in do_signal_stop() on return, so notifying + * the real parent of the group stop completion is enough. + */ + if (gstop_done) + do_notify_parent_cldstop(current, false, why); + + /* tasklist protects us from ptrace_freeze_traced() */ + __set_current_state(TASK_RUNNING); + if (clear_code) + current->exit_code = 0; + read_unlock(&tasklist_lock); + } + + /* + * 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; + + /* LISTENING can be set only during STOP traps, clear it */ + current->jobctl &= ~JOBCTL_LISTENING; + + /* + * 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); +} + +static void ptrace_do_notify(int signr, int exit_code, int why) +{ + siginfo_t info; + + clear_siginfo(&info); + info.si_signo = signr; + info.si_code = exit_code; + info.si_pid = task_pid_vnr(current); + info.si_uid = from_kuid_munged(current_user_ns(), current_uid()); + + /* Let the debugger run. */ + ptrace_stop(exit_code, why, 1, &info); +} + +void ptrace_notify(int exit_code) +{ + BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP); + if (unlikely(current->task_works)) + task_work_run(); + + spin_lock_irq(¤t->sighand->siglock); + ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED); + spin_unlock_irq(¤t->sighand->siglock); +} + +/** + * do_signal_stop - handle group stop for SIGSTOP and other stop signals + * @signr: signr causing group stop if initiating + * + * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr + * and participate in it. If already set, participate in the existing + * group stop. If participated in a group stop (and thus slept), %true is + * returned with siglock released. + * + * If ptraced, this function doesn't handle stop itself. Instead, + * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock + * untouched. The caller must ensure that INTERRUPT trap handling takes + * places afterwards. + * + * CONTEXT: + * Must be called with @current->sighand->siglock held, which is released + * on %true return. + * + * RETURNS: + * %false if group stop is already cancelled or ptrace trap is scheduled. + * %true if participated in group stop. + */ +static bool do_signal_stop(int signr) + __releases(¤t->sighand->siglock) +{ + struct signal_struct *sig = current->signal; + + if (!(current->jobctl & JOBCTL_STOP_PENDING)) { + unsigned long gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME; + struct task_struct *t; + + /* signr will be recorded in task->jobctl for retries */ + WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK); + + if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) || + unlikely(signal_group_exit(sig))) + return false; + /* + * There is no group stop already in progress. We must + * initiate one now. + * + * While ptraced, a task may be resumed while group stop is + * still in effect and then receive a stop signal and + * initiate another group stop. This deviates from the + * usual behavior as two consecutive stop signals can't + * cause two group stops when !ptraced. That is why we + * also check !task_is_stopped(t) below. + * + * The condition can be distinguished by testing whether + * SIGNAL_STOP_STOPPED is already set. Don't generate + * group_exit_code in such case. + * + * This is not necessary for SIGNAL_STOP_CONTINUED because + * an intervening stop signal is required to cause two + * continued events regardless of ptrace. + */ + if (!(sig->flags & SIGNAL_STOP_STOPPED)) + sig->group_exit_code = signr; + + sig->group_stop_count = 0; + + if (task_set_jobctl_pending(current, signr | gstop)) + sig->group_stop_count++; + + t = current; + while_each_thread(current, t) { + /* + * Setting state to TASK_STOPPED for a group + * stop is always done with the siglock held, + * so this check has no races. + */ + if (!task_is_stopped(t) && + task_set_jobctl_pending(t, signr | gstop)) { + sig->group_stop_count++; + if (likely(!(t->ptrace & PT_SEIZED))) + signal_wake_up(t, 0); + else + ptrace_trap_notify(t); + } + } + } + + if (likely(!current->ptrace)) { + int notify = 0; + + /* + * If there are no other threads in the group, or if there + * is a group stop in progress and we are the last to stop, + * report to the parent. + */ + if (task_participate_group_stop(current)) + notify = CLD_STOPPED; + + set_special_state(TASK_STOPPED); + spin_unlock_irq(¤t->sighand->siglock); + + /* + * Notify the parent of the group stop completion. Because + * we're not holding either the siglock or tasklist_lock + * here, ptracer may attach inbetween; however, this is for + * group stop and should always be delivered to the real + * parent of the group leader. The new ptracer will get + * its notification when this task transitions into + * TASK_TRACED. + */ + if (notify) { + read_lock(&tasklist_lock); + do_notify_parent_cldstop(current, false, notify); + read_unlock(&tasklist_lock); + } + + /* Now we don't run again until woken by SIGCONT or SIGKILL */ + freezable_schedule(); + return true; + } else { + /* + * While ptraced, group stop is handled by STOP trap. + * Schedule it and let the caller deal with it. + */ + task_set_jobctl_pending(current, JOBCTL_TRAP_STOP); + return false; + } +} + +/** + * do_jobctl_trap - take care of ptrace jobctl traps + * + * When PT_SEIZED, it's used for both group stop and explicit + * SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with + * accompanying siginfo. If stopped, lower eight bits of exit_code contain + * the stop signal; otherwise, %SIGTRAP. + * + * When !PT_SEIZED, it's used only for group stop trap with stop signal + * number as exit_code and no siginfo. + * + * CONTEXT: + * Must be called with @current->sighand->siglock held, which may be + * released and re-acquired before returning with intervening sleep. + */ +static void do_jobctl_trap(void) +{ + struct signal_struct *signal = current->signal; + int signr = current->jobctl & JOBCTL_STOP_SIGMASK; + + if (current->ptrace & PT_SEIZED) { + if (!signal->group_stop_count && + !(signal->flags & SIGNAL_STOP_STOPPED)) + signr = SIGTRAP; + WARN_ON_ONCE(!signr); + ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8), + CLD_STOPPED); + } else { + WARN_ON_ONCE(!signr); + ptrace_stop(signr, CLD_STOPPED, 0, NULL); + current->exit_code = 0; + } +} + +static int ptrace_signal(int signr, siginfo_t *info) +{ + /* + * We do not check sig_kernel_stop(signr) but set this marker + * unconditionally because we do not know whether debugger will + * change signr. This flag has no meaning unless we are going + * to stop after return from ptrace_stop(). In this case it will + * be checked in do_signal_stop(), we should only stop if it was + * not cleared by SIGCONT while we were sleeping. See also the + * comment in dequeue_signal(). + */ + current->jobctl |= JOBCTL_STOP_DEQUEUED; + ptrace_stop(signr, CLD_TRAPPED, 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) { + clear_siginfo(info); + info->si_signo = signr; + info->si_errno = 0; + info->si_code = SI_USER; + rcu_read_lock(); + info->si_pid = task_pid_vnr(current->parent); + info->si_uid = from_kuid_munged(current_user_ns(), + task_uid(current->parent)); + rcu_read_unlock(); + } + + /* If the (new) signal is now blocked, requeue it. */ + if (sigismember(¤t->blocked, signr)) { + specific_send_sig_info(signr, info, current); + signr = 0; + } + + return signr; +} + +bool get_signal(struct ksignal *ksig) +{ + struct sighand_struct *sighand = current->sighand; + struct signal_struct *signal = current->signal; + int signr; + + if (unlikely(current->task_works)) + task_work_run(); + + if (unlikely(uprobe_deny_signal())) + return false; + + /* + * Do this once, we can't return to user-mode if freezing() == T. + * do_signal_stop() and ptrace_stop() do freezable_schedule() and + * thus do not need another check after return. + */ + try_to_freeze(); + +relock: + spin_lock_irq(&sighand->siglock); + /* + * Every stopped thread goes here after wakeup. Check to see if + * we should notify the parent, prepare_signal(SIGCONT) encodes + * the CLD_ si_code into SIGNAL_CLD_MASK bits. + */ + if (unlikely(signal->flags & SIGNAL_CLD_MASK)) { + int why; + + if (signal->flags & SIGNAL_CLD_CONTINUED) + why = CLD_CONTINUED; + else + why = CLD_STOPPED; + + signal->flags &= ~SIGNAL_CLD_MASK; + + spin_unlock_irq(&sighand->siglock); + + /* + * Notify the parent that we're continuing. This event is + * always per-process and doesn't make whole lot of sense + * for ptracers, who shouldn't consume the state via + * wait(2) either, but, for backward compatibility, notify + * the ptracer of the group leader too unless it's gonna be + * a duplicate. + */ + read_lock(&tasklist_lock); + do_notify_parent_cldstop(current, false, why); + + if (ptrace_reparented(current->group_leader)) + do_notify_parent_cldstop(current->group_leader, + true, why); + read_unlock(&tasklist_lock); + + goto relock; + } + + /* Has this task already been marked for death? */ + if (signal_group_exit(signal)) { + ksig->info.si_signo = signr = SIGKILL; + sigdelset(¤t->pending.signal, SIGKILL); + trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO, + &sighand->action[SIGKILL - 1]); + recalc_sigpending(); + goto fatal; + } + + for (;;) { + struct k_sigaction *ka; + + if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) && + do_signal_stop(0)) + goto relock; + + if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) { + do_jobctl_trap(); + spin_unlock_irq(&sighand->siglock); + goto relock; + } + + /* + * Signals generated by the execution of an instruction + * need to be delivered before any other pending signals + * so that the instruction pointer in the signal stack + * frame points to the faulting instruction. + */ + signr = dequeue_synchronous_signal(&ksig->info); + if (!signr) + signr = dequeue_signal(current, ¤t->blocked, &ksig->info); + + if (!signr) + break; /* will return 0 */ + + if (unlikely(current->ptrace) && signr != SIGKILL) { + signr = ptrace_signal(signr, &ksig->info); + if (!signr) + continue; + } + + ka = &sighand->action[signr-1]; + + /* Trace actually delivered signals. */ + trace_signal_deliver(signr, &ksig->info, ka); + + if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */ + continue; + if (ka->sa.sa_handler != SIG_DFL) { + /* Run the handler. */ + ksig->ka = *ka; + + if (ka->sa.sa_flags & SA_ONESHOT) + ka->sa.sa_handler = SIG_DFL; + + break; /* will return non-zero "signr" value */ + } + + /* + * Now we are doing the default action for this signal. + */ + if (sig_kernel_ignore(signr)) /* Default is nothing. */ + continue; + + /* + * Global init gets no signals it doesn't want. + * Container-init gets no signals it doesn't want from same + * container. + * + * Note that if global/container-init sees a sig_kernel_only() + * signal here, the signal must have been generated internally + * or must have come from an ancestor namespace. In either + * case, the signal cannot be dropped. + */ + if (unlikely(signal->flags & SIGNAL_UNKILLABLE) && + !sig_kernel_only(signr)) + continue; + + if (sig_kernel_stop(signr)) { + /* + * The default action is to stop all threads in + * the thread group. The job control signals + * do nothing in an orphaned pgrp, but SIGSTOP + * always works. Note that siglock needs to be + * dropped during the call to is_orphaned_pgrp() + * because of lock ordering with tasklist_lock. + * This allows an intervening SIGCONT to be posted. + * We need to check for that and bail out if necessary. + */ + if (signr != SIGSTOP) { + spin_unlock_irq(&sighand->siglock); + + /* signals can be posted during this window */ + + if (is_current_pgrp_orphaned()) + goto relock; + + spin_lock_irq(&sighand->siglock); + } + + if (likely(do_signal_stop(ksig->info.si_signo))) { + /* It released the siglock. */ + goto relock; + } + + /* + * We didn't actually stop, due to a race + * with SIGCONT or something like that. + */ + continue; + } + + fatal: + spin_unlock_irq(&sighand->siglock); + + /* + * Anything else is fatal, maybe with a core dump. + */ + current->flags |= PF_SIGNALED; + + if (sig_kernel_coredump(signr)) { + if (print_fatal_signals) + print_fatal_signal(ksig->info.si_signo); + proc_coredump_connector(current); + /* + * If it was able to dump core, this kills all + * other threads in the group and synchronizes with + * their demise. If we lost the race with another + * thread getting here, it set group_exit_code + * first and our do_group_exit call below will use + * that value and ignore the one we pass it. + */ + do_coredump(&ksig->info); + } + + /* + * Death signals, no core dump. + */ + do_group_exit(ksig->info.si_signo); + /* NOTREACHED */ + } + spin_unlock_irq(&sighand->siglock); + + ksig->sig = signr; + return ksig->sig > 0; +} + +/** + * signal_delivered - + * @ksig: kernel signal struct + * @stepping: nonzero if debugger single-step or block-step in use + * + * This function should be called when a signal has successfully been + * delivered. It updates the blocked signals accordingly (@ksig->ka.sa.sa_mask + * is always blocked, and the signal itself is blocked unless %SA_NODEFER + * is set in @ksig->ka.sa.sa_flags. Tracing is notified. + */ +static void signal_delivered(struct ksignal *ksig, int stepping) +{ + sigset_t blocked; + + /* A signal was successfully delivered, and the + saved sigmask was stored on the signal frame, + and will be restored by sigreturn. So we can + simply clear the restore sigmask flag. */ + clear_restore_sigmask(); + + sigorsets(&blocked, ¤t->blocked, &ksig->ka.sa.sa_mask); + if (!(ksig->ka.sa.sa_flags & SA_NODEFER)) + sigaddset(&blocked, ksig->sig); + set_current_blocked(&blocked); + tracehook_signal_handler(stepping); +} + +void signal_setup_done(int failed, struct ksignal *ksig, int stepping) +{ + if (failed) + force_sigsegv(ksig->sig, current); + else + signal_delivered(ksig, stepping); +} + +/* + * It could be that complete_signal() picked us to notify about the + * group-wide signal. Other threads should be notified now to take + * the shared signals in @which since we will not. + */ +static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which) +{ + sigset_t retarget; + struct task_struct *t; + + sigandsets(&retarget, &tsk->signal->shared_pending.signal, which); + if (sigisemptyset(&retarget)) + return; + + t = tsk; + while_each_thread(tsk, t) { + if (t->flags & PF_EXITING) + continue; + + if (!has_pending_signals(&retarget, &t->blocked)) + continue; + /* Remove the signals this thread can handle. */ + sigandsets(&retarget, &retarget, &t->blocked); + + if (!signal_pending(t)) + signal_wake_up(t, 0); + + if (sigisemptyset(&retarget)) + break; + } +} + +void exit_signals(struct task_struct *tsk) +{ + int group_stop = 0; + sigset_t unblocked; + + /* + * @tsk is about to have PF_EXITING set - lock out users which + * expect stable threadgroup. + */ + cgroup_threadgroup_change_begin(tsk); + + if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) { + tsk->flags |= PF_EXITING; + cgroup_threadgroup_change_end(tsk); + return; + } + + spin_lock_irq(&tsk->sighand->siglock); + /* + * From now this task is not visible for group-wide signals, + * see wants_signal(), do_signal_stop(). + */ + tsk->flags |= PF_EXITING; + + cgroup_threadgroup_change_end(tsk); + + if (!signal_pending(tsk)) + goto out; + + unblocked = tsk->blocked; + signotset(&unblocked); + retarget_shared_pending(tsk, &unblocked); + + if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) && + task_participate_group_stop(tsk)) + group_stop = CLD_STOPPED; +out: + spin_unlock_irq(&tsk->sighand->siglock); + + /* + * If group stop has completed, deliver the notification. This + * should always go to the real parent of the group leader. + */ + if (unlikely(group_stop)) { + read_lock(&tasklist_lock); + do_notify_parent_cldstop(tsk, false, group_stop); + read_unlock(&tasklist_lock); + } +} + +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); + +/* + * System call entry points. + */ + +/** + * sys_restart_syscall - restart a system call + */ +SYSCALL_DEFINE0(restart_syscall) +{ + struct restart_block *restart = ¤t->restart_block; + return restart->fn(restart); +} + +long do_no_restart_syscall(struct restart_block *param) +{ + return -EINTR; +} + +static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset) +{ + if (signal_pending(tsk) && !thread_group_empty(tsk)) { + sigset_t newblocked; + /* A set of now blocked but previously unblocked signals. */ + sigandnsets(&newblocked, newset, ¤t->blocked); + retarget_shared_pending(tsk, &newblocked); + } + tsk->blocked = *newset; + recalc_sigpending(); +} + +/** + * set_current_blocked - change current->blocked mask + * @newset: new mask + * + * It is wrong to change ->blocked directly, this helper should be used + * to ensure the process can't miss a shared signal we are going to block. + */ +void set_current_blocked(sigset_t *newset) +{ + sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP)); + __set_current_blocked(newset); +} + +void __set_current_blocked(const sigset_t *newset) +{ + struct task_struct *tsk = current; + + /* + * In case the signal mask hasn't changed, there is nothing we need + * to do. The current->blocked shouldn't be modified by other task. + */ + if (sigequalsets(&tsk->blocked, newset)) + return; + + spin_lock_irq(&tsk->sighand->siglock); + __set_task_blocked(tsk, newset); + spin_unlock_irq(&tsk->sighand->siglock); +} + +/* + * This is also useful for kernel threads that want to temporarily + * (or permanently) block certain signals. + * + * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel + * interface happily blocks "unblockable" signals like SIGKILL + * and friends. + */ +int sigprocmask(int how, sigset_t *set, sigset_t *oldset) +{ + struct task_struct *tsk = current; + sigset_t newset; + + /* Lockless, only current can change ->blocked, never from irq */ + if (oldset) + *oldset = tsk->blocked; + + switch (how) { + case SIG_BLOCK: + sigorsets(&newset, &tsk->blocked, set); + break; + case SIG_UNBLOCK: + sigandnsets(&newset, &tsk->blocked, set); + break; + case SIG_SETMASK: + newset = *set; + break; + default: + return -EINVAL; + } + + __set_current_blocked(&newset); + return 0; +} + +/** + * sys_rt_sigprocmask - change the list of currently blocked signals + * @how: whether to add, remove, or set signals + * @nset: stores pending signals + * @oset: previous value of signal mask if non-null + * @sigsetsize: size of sigset_t type + */ +SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset, + sigset_t __user *, oset, size_t, sigsetsize) +{ + sigset_t old_set, new_set; + int error; + + /* XXX: Don't preclude handling different sized sigset_t's. */ + if (sigsetsize != sizeof(sigset_t)) + return -EINVAL; + + old_set = current->blocked; + + if (nset) { + if (copy_from_user(&new_set, nset, sizeof(sigset_t))) + return -EFAULT; + sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); + + error = sigprocmask(how, &new_set, NULL); + if (error) + return error; + } + + if (oset) { + if (copy_to_user(oset, &old_set, sizeof(sigset_t))) + return -EFAULT; + } + + return 0; +} + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE4(rt_sigprocmask, int, how, compat_sigset_t __user *, nset, + compat_sigset_t __user *, oset, compat_size_t, sigsetsize) +{ + sigset_t old_set = current->blocked; + + /* XXX: Don't preclude handling different sized sigset_t's. */ + if (sigsetsize != sizeof(sigset_t)) + return -EINVAL; + + if (nset) { + sigset_t new_set; + int error; + if (get_compat_sigset(&new_set, nset)) + return -EFAULT; + sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); + + error = sigprocmask(how, &new_set, NULL); + if (error) + return error; + } + return oset ? put_compat_sigset(oset, &old_set, sizeof(*oset)) : 0; +} +#endif + +static void do_sigpending(sigset_t *set) +{ + spin_lock_irq(¤t->sighand->siglock); + sigorsets(set, ¤t->pending.signal, + ¤t->signal->shared_pending.signal); + spin_unlock_irq(¤t->sighand->siglock); + + /* Outside the lock because only this thread touches it. */ + sigandsets(set, ¤t->blocked, set); +} + +/** + * sys_rt_sigpending - examine a pending signal that has been raised + * while blocked + * @uset: stores pending signals + * @sigsetsize: size of sigset_t type or larger + */ +SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, uset, size_t, sigsetsize) +{ + sigset_t set; + + if (sigsetsize > sizeof(*uset)) + return -EINVAL; + + do_sigpending(&set); + + if (copy_to_user(uset, &set, sigsetsize)) + return -EFAULT; + + return 0; +} + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset, + compat_size_t, sigsetsize) +{ + sigset_t set; + + if (sigsetsize > sizeof(*uset)) + return -EINVAL; + + do_sigpending(&set); + + return put_compat_sigset(uset, &set, sigsetsize); +} +#endif + +enum siginfo_layout siginfo_layout(unsigned sig, int si_code) +{ + enum siginfo_layout layout = SIL_KILL; + if ((si_code > SI_USER) && (si_code < SI_KERNEL)) { + static const struct { + unsigned char limit, layout; + } filter[] = { + [SIGILL] = { NSIGILL, SIL_FAULT }, + [SIGFPE] = { NSIGFPE, SIL_FAULT }, + [SIGSEGV] = { NSIGSEGV, SIL_FAULT }, + [SIGBUS] = { NSIGBUS, SIL_FAULT }, + [SIGTRAP] = { NSIGTRAP, SIL_FAULT }, +#if defined(SIGEMT) && defined(NSIGEMT) + [SIGEMT] = { NSIGEMT, SIL_FAULT }, +#endif + [SIGCHLD] = { NSIGCHLD, SIL_CHLD }, + [SIGPOLL] = { NSIGPOLL, SIL_POLL }, + [SIGSYS] = { NSIGSYS, SIL_SYS }, + }; + if ((sig < ARRAY_SIZE(filter)) && (si_code <= filter[sig].limit)) { + layout = filter[sig].layout; + /* Handle the exceptions */ + if ((sig == SIGBUS) && + (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO)) + layout = SIL_FAULT_MCEERR; + else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR)) + layout = SIL_FAULT_BNDERR; +#ifdef SEGV_PKUERR + else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR)) + layout = SIL_FAULT_PKUERR; +#endif + } + else if (si_code <= NSIGPOLL) + layout = SIL_POLL; + } else { + if (si_code == SI_TIMER) + layout = SIL_TIMER; + else if (si_code == SI_SIGIO) + layout = SIL_POLL; + else if (si_code < 0) + layout = SIL_RT; + } + return layout; +} + +int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from) +{ + if (copy_to_user(to, from , sizeof(struct siginfo))) + return -EFAULT; + return 0; +} + +#ifdef CONFIG_COMPAT +int copy_siginfo_to_user32(struct compat_siginfo __user *to, + const struct siginfo *from) +#if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION) +{ + return __copy_siginfo_to_user32(to, from, in_x32_syscall()); +} +int __copy_siginfo_to_user32(struct compat_siginfo __user *to, + const struct siginfo *from, bool x32_ABI) +#endif +{ + struct compat_siginfo new; + memset(&new, 0, sizeof(new)); + + new.si_signo = from->si_signo; + new.si_errno = from->si_errno; + new.si_code = from->si_code; + switch(siginfo_layout(from->si_signo, from->si_code)) { + case SIL_KILL: + new.si_pid = from->si_pid; + new.si_uid = from->si_uid; + break; + case SIL_TIMER: + new.si_tid = from->si_tid; + new.si_overrun = from->si_overrun; + new.si_int = from->si_int; + break; + case SIL_POLL: + new.si_band = from->si_band; + new.si_fd = from->si_fd; + break; + case SIL_FAULT: + new.si_addr = ptr_to_compat(from->si_addr); +#ifdef __ARCH_SI_TRAPNO + new.si_trapno = from->si_trapno; +#endif + break; + case SIL_FAULT_MCEERR: + new.si_addr = ptr_to_compat(from->si_addr); +#ifdef __ARCH_SI_TRAPNO + new.si_trapno = from->si_trapno; +#endif + new.si_addr_lsb = from->si_addr_lsb; + break; + case SIL_FAULT_BNDERR: + new.si_addr = ptr_to_compat(from->si_addr); +#ifdef __ARCH_SI_TRAPNO + new.si_trapno = from->si_trapno; +#endif + new.si_lower = ptr_to_compat(from->si_lower); + new.si_upper = ptr_to_compat(from->si_upper); + break; + case SIL_FAULT_PKUERR: + new.si_addr = ptr_to_compat(from->si_addr); +#ifdef __ARCH_SI_TRAPNO + new.si_trapno = from->si_trapno; +#endif + new.si_pkey = from->si_pkey; + break; + case SIL_CHLD: + new.si_pid = from->si_pid; + new.si_uid = from->si_uid; + new.si_status = from->si_status; +#ifdef CONFIG_X86_X32_ABI + if (x32_ABI) { + new._sifields._sigchld_x32._utime = from->si_utime; + new._sifields._sigchld_x32._stime = from->si_stime; + } else +#endif + { + new.si_utime = from->si_utime; + new.si_stime = from->si_stime; + } + break; + case SIL_RT: + new.si_pid = from->si_pid; + new.si_uid = from->si_uid; + new.si_int = from->si_int; + break; + case SIL_SYS: + new.si_call_addr = ptr_to_compat(from->si_call_addr); + new.si_syscall = from->si_syscall; + new.si_arch = from->si_arch; + break; + } + + if (copy_to_user(to, &new, sizeof(struct compat_siginfo))) + return -EFAULT; + + return 0; +} + +int copy_siginfo_from_user32(struct siginfo *to, + const struct compat_siginfo __user *ufrom) +{ + struct compat_siginfo from; + + if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo))) + return -EFAULT; + + clear_siginfo(to); + to->si_signo = from.si_signo; + to->si_errno = from.si_errno; + to->si_code = from.si_code; + switch(siginfo_layout(from.si_signo, from.si_code)) { + case SIL_KILL: + to->si_pid = from.si_pid; + to->si_uid = from.si_uid; + break; + case SIL_TIMER: + to->si_tid = from.si_tid; + to->si_overrun = from.si_overrun; + to->si_int = from.si_int; + break; + case SIL_POLL: + to->si_band = from.si_band; + to->si_fd = from.si_fd; + break; + case SIL_FAULT: + to->si_addr = compat_ptr(from.si_addr); +#ifdef __ARCH_SI_TRAPNO + to->si_trapno = from.si_trapno; +#endif + break; + case SIL_FAULT_MCEERR: + to->si_addr = compat_ptr(from.si_addr); +#ifdef __ARCH_SI_TRAPNO + to->si_trapno = from.si_trapno; +#endif + to->si_addr_lsb = from.si_addr_lsb; + break; + case SIL_FAULT_BNDERR: + to->si_addr = compat_ptr(from.si_addr); +#ifdef __ARCH_SI_TRAPNO + to->si_trapno = from.si_trapno; +#endif + to->si_lower = compat_ptr(from.si_lower); + to->si_upper = compat_ptr(from.si_upper); + break; + case SIL_FAULT_PKUERR: + to->si_addr = compat_ptr(from.si_addr); +#ifdef __ARCH_SI_TRAPNO + to->si_trapno = from.si_trapno; +#endif + to->si_pkey = from.si_pkey; + break; + case SIL_CHLD: + to->si_pid = from.si_pid; + to->si_uid = from.si_uid; + to->si_status = from.si_status; +#ifdef CONFIG_X86_X32_ABI + if (in_x32_syscall()) { + to->si_utime = from._sifields._sigchld_x32._utime; + to->si_stime = from._sifields._sigchld_x32._stime; + } else +#endif + { + to->si_utime = from.si_utime; + to->si_stime = from.si_stime; + } + break; + case SIL_RT: + to->si_pid = from.si_pid; + to->si_uid = from.si_uid; + to->si_int = from.si_int; + break; + case SIL_SYS: + to->si_call_addr = compat_ptr(from.si_call_addr); + to->si_syscall = from.si_syscall; + to->si_arch = from.si_arch; + break; + } + return 0; +} +#endif /* CONFIG_COMPAT */ + +/** + * do_sigtimedwait - wait for queued signals specified in @which + * @which: queued signals to wait for + * @info: if non-null, the signal's siginfo is returned here + * @ts: upper bound on process time suspension + */ +static int do_sigtimedwait(const sigset_t *which, siginfo_t *info, + const struct timespec *ts) +{ + ktime_t *to = NULL, timeout = KTIME_MAX; + struct task_struct *tsk = current; + sigset_t mask = *which; + int sig, ret = 0; + + if (ts) { + if (!timespec_valid(ts)) + return -EINVAL; + timeout = timespec_to_ktime(*ts); + to = &timeout; + } + + /* + * Invert the set of allowed signals to get those we want to block. + */ + sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP)); + signotset(&mask); + + spin_lock_irq(&tsk->sighand->siglock); + sig = dequeue_signal(tsk, &mask, info); + if (!sig && timeout) { + /* + * None ready, temporarily unblock those we're interested + * while we are sleeping in so that we'll be awakened when + * they arrive. Unblocking is always fine, we can avoid + * set_current_blocked(). + */ + tsk->real_blocked = tsk->blocked; + sigandsets(&tsk->blocked, &tsk->blocked, &mask); + recalc_sigpending(); + spin_unlock_irq(&tsk->sighand->siglock); + + __set_current_state(TASK_INTERRUPTIBLE); + ret = freezable_schedule_hrtimeout_range(to, tsk->timer_slack_ns, + HRTIMER_MODE_REL); + spin_lock_irq(&tsk->sighand->siglock); + __set_task_blocked(tsk, &tsk->real_blocked); + sigemptyset(&tsk->real_blocked); + sig = dequeue_signal(tsk, &mask, info); + } + spin_unlock_irq(&tsk->sighand->siglock); + + if (sig) + return sig; + return ret ? -EINTR : -EAGAIN; +} + +/** + * 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) +{ + sigset_t these; + struct timespec ts; + siginfo_t info; + int ret; + + /* 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; + + if (uts) { + if (copy_from_user(&ts, uts, sizeof(ts))) + return -EFAULT; + } + + ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL); + + if (ret > 0 && uinfo) { + if (copy_siginfo_to_user(uinfo, &info)) + ret = -EFAULT; + } + + return ret; +} + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE4(rt_sigtimedwait, compat_sigset_t __user *, uthese, + struct compat_siginfo __user *, uinfo, + struct compat_timespec __user *, uts, compat_size_t, sigsetsize) +{ + sigset_t s; + struct timespec t; + siginfo_t info; + long ret; + + if (sigsetsize != sizeof(sigset_t)) + return -EINVAL; + + if (get_compat_sigset(&s, uthese)) + return -EFAULT; + + if (uts) { + if (compat_get_timespec(&t, uts)) + return -EFAULT; + } + + ret = do_sigtimedwait(&s, &info, uts ? &t : NULL); + + if (ret > 0 && uinfo) { + if (copy_siginfo_to_user32(uinfo, &info)) + ret = -EFAULT; + } + + return ret; +} +#endif + +/** + * 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; + + clear_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 = from_kuid_munged(current_user_ns(), 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, PIDTYPE_PID); + /* + * 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; + + clear_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 = from_kuid_munged(current_user_ns(), 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); +} + +static int do_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t *info) +{ + /* 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) && + (task_pid_vnr(current) != pid)) + return -EPERM; + + info->si_signo = sig; + + /* POSIX.1b doesn't mention process groups. */ + return kill_proc_info(sig, info, pid); +} + +/** + * 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; + return do_rt_sigqueueinfo(pid, sig, &info); +} + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo, + compat_pid_t, pid, + int, sig, + struct compat_siginfo __user *, uinfo) +{ + siginfo_t info; + int ret = copy_siginfo_from_user32(&info, uinfo); + if (unlikely(ret)) + return ret; + return do_rt_sigqueueinfo(pid, sig, &info); +} +#endif + +static int 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) && + (task_pid_vnr(current) != pid)) + 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); +} + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo, + compat_pid_t, tgid, + compat_pid_t, pid, + int, sig, + struct compat_siginfo __user *, uinfo) +{ + siginfo_t info; + + if (copy_siginfo_from_user32(&info, uinfo)) + return -EFAULT; + return do_rt_tgsigqueueinfo(tgid, pid, sig, &info); +} +#endif + +/* + * For kthreads only, must not be used if cloned with CLONE_SIGHAND + */ +void kernel_sigaction(int sig, __sighandler_t action) +{ + spin_lock_irq(¤t->sighand->siglock); + current->sighand->action[sig - 1].sa.sa_handler = action; + if (action == SIG_IGN) { + sigset_t mask; + + sigemptyset(&mask); + sigaddset(&mask, sig); + + flush_sigqueue_mask(&mask, ¤t->signal->shared_pending); + flush_sigqueue_mask(&mask, ¤t->pending); + recalc_sigpending(); + } + spin_unlock_irq(¤t->sighand->siglock); +} +EXPORT_SYMBOL(kernel_sigaction); + +void __weak sigaction_compat_abi(struct k_sigaction *act, + struct k_sigaction *oact) +{ +} + +int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) +{ + struct task_struct *p = current, *t; + struct k_sigaction *k; + sigset_t mask; + + if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig))) + return -EINVAL; + + k = &p->sighand->action[sig-1]; + + spin_lock_irq(&p->sighand->siglock); + if (oact) + *oact = *k; + + sigaction_compat_abi(act, oact); + + 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(p, sig), sig)) { + sigemptyset(&mask); + sigaddset(&mask, sig); + flush_sigqueue_mask(&mask, &p->signal->shared_pending); + for_each_thread(p, t) + flush_sigqueue_mask(&mask, &t->pending); + } + } + + spin_unlock_irq(&p->sighand->siglock); + return 0; +} + +static int +do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp, + size_t min_ss_size) +{ + struct task_struct *t = current; + + if (oss) { + memset(oss, 0, sizeof(stack_t)); + oss->ss_sp = (void __user *) t->sas_ss_sp; + oss->ss_size = t->sas_ss_size; + oss->ss_flags = sas_ss_flags(sp) | + (current->sas_ss_flags & SS_FLAG_BITS); + } + + if (ss) { + void __user *ss_sp = ss->ss_sp; + size_t ss_size = ss->ss_size; + unsigned ss_flags = ss->ss_flags; + int ss_mode; + + if (unlikely(on_sig_stack(sp))) + return -EPERM; + + ss_mode = ss_flags & ~SS_FLAG_BITS; + if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK && + ss_mode != 0)) + return -EINVAL; + + if (ss_mode == SS_DISABLE) { + ss_size = 0; + ss_sp = NULL; + } else { + if (unlikely(ss_size < min_ss_size)) + return -ENOMEM; + } + + t->sas_ss_sp = (unsigned long) ss_sp; + t->sas_ss_size = ss_size; + t->sas_ss_flags = ss_flags; + } + return 0; +} + +SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss) +{ + stack_t new, old; + int err; + if (uss && copy_from_user(&new, uss, sizeof(stack_t))) + return -EFAULT; + err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL, + current_user_stack_pointer(), + MINSIGSTKSZ); + if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t))) + err = -EFAULT; + return err; +} + +int restore_altstack(const stack_t __user *uss) +{ + stack_t new; + if (copy_from_user(&new, uss, sizeof(stack_t))) + return -EFAULT; + (void)do_sigaltstack(&new, NULL, current_user_stack_pointer(), + MINSIGSTKSZ); + /* squash all but EFAULT for now */ + return 0; +} + +int __save_altstack(stack_t __user *uss, unsigned long sp) +{ + struct task_struct *t = current; + int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) | + __put_user(t->sas_ss_flags, &uss->ss_flags) | + __put_user(t->sas_ss_size, &uss->ss_size); + if (err) + return err; + if (t->sas_ss_flags & SS_AUTODISARM) + sas_ss_reset(t); + return 0; +} + +#ifdef CONFIG_COMPAT +static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr, + compat_stack_t __user *uoss_ptr) +{ + stack_t uss, uoss; + int ret; + + if (uss_ptr) { + compat_stack_t uss32; + if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t))) + return -EFAULT; + uss.ss_sp = compat_ptr(uss32.ss_sp); + uss.ss_flags = uss32.ss_flags; + uss.ss_size = uss32.ss_size; + } + ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss, + compat_user_stack_pointer(), + COMPAT_MINSIGSTKSZ); + if (ret >= 0 && uoss_ptr) { + compat_stack_t old; + memset(&old, 0, sizeof(old)); + old.ss_sp = ptr_to_compat(uoss.ss_sp); + old.ss_flags = uoss.ss_flags; + old.ss_size = uoss.ss_size; + if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t))) + ret = -EFAULT; + } + return ret; +} + +COMPAT_SYSCALL_DEFINE2(sigaltstack, + const compat_stack_t __user *, uss_ptr, + compat_stack_t __user *, uoss_ptr) +{ + return do_compat_sigaltstack(uss_ptr, uoss_ptr); +} + +int compat_restore_altstack(const compat_stack_t __user *uss) +{ + int err = do_compat_sigaltstack(uss, NULL); + /* squash all but -EFAULT for now */ + return err == -EFAULT ? err : 0; +} + +int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp) +{ + int err; + struct task_struct *t = current; + err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), + &uss->ss_sp) | + __put_user(t->sas_ss_flags, &uss->ss_flags) | + __put_user(t->sas_ss_size, &uss->ss_size); + if (err) + return err; + if (t->sas_ss_flags & SS_AUTODISARM) + sas_ss_reset(t); + return 0; +} +#endif + +#ifdef __ARCH_WANT_SYS_SIGPENDING + +/** + * sys_sigpending - examine pending signals + * @uset: where mask of pending signal is returned + */ +SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, uset) +{ + sigset_t set; + + if (sizeof(old_sigset_t) > sizeof(*uset)) + return -EINVAL; + + do_sigpending(&set); + + if (copy_to_user(uset, &set, sizeof(old_sigset_t))) + return -EFAULT; + + return 0; +} + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32) +{ + sigset_t set; + + do_sigpending(&set); + + return put_user(set.sig[0], set32); +} +#endif + +#endif + +#ifdef __ARCH_WANT_SYS_SIGPROCMASK +/** + * sys_sigprocmask - examine and change blocked signals + * @how: whether to add, remove, or set signals + * @nset: 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 *, nset, + old_sigset_t __user *, oset) +{ + old_sigset_t old_set, new_set; + sigset_t new_blocked; + + old_set = current->blocked.sig[0]; + + if (nset) { + if (copy_from_user(&new_set, nset, sizeof(*nset))) + return -EFAULT; + + new_blocked = current->blocked; + + switch (how) { + case SIG_BLOCK: + sigaddsetmask(&new_blocked, new_set); + break; + case SIG_UNBLOCK: + sigdelsetmask(&new_blocked, new_set); + break; + case SIG_SETMASK: + new_blocked.sig[0] = new_set; + break; + default: + return -EINVAL; + } + + set_current_blocked(&new_blocked); + } + + if (oset) { + if (copy_to_user(oset, &old_set, sizeof(*oset))) + return -EFAULT; + } + + return 0; +} +#endif /* __ARCH_WANT_SYS_SIGPROCMASK */ + +#ifndef CONFIG_ODD_RT_SIGACTION +/** + * sys_rt_sigaction - alter an action taken by a process + * @sig: signal to be sent + * @act: new sigaction + * @oact: used to save the previous sigaction + * @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; + + /* XXX: Don't preclude handling different sized sigset_t's. */ + if (sigsetsize != sizeof(sigset_t)) + return -EINVAL; + + if (act && 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) + return ret; + + if (oact && copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa))) + return -EFAULT; + + return 0; +} +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig, + const struct compat_sigaction __user *, act, + struct compat_sigaction __user *, oact, + compat_size_t, sigsetsize) +{ + struct k_sigaction new_ka, old_ka; +#ifdef __ARCH_HAS_SA_RESTORER + compat_uptr_t restorer; +#endif + int ret; + + /* XXX: Don't preclude handling different sized sigset_t's. */ + if (sigsetsize != sizeof(compat_sigset_t)) + return -EINVAL; + + if (act) { + compat_uptr_t handler; + ret = get_user(handler, &act->sa_handler); + new_ka.sa.sa_handler = compat_ptr(handler); +#ifdef __ARCH_HAS_SA_RESTORER + ret |= get_user(restorer, &act->sa_restorer); + new_ka.sa.sa_restorer = compat_ptr(restorer); +#endif + ret |= get_compat_sigset(&new_ka.sa.sa_mask, &act->sa_mask); + ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags); + if (ret) + return -EFAULT; + } + + ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); + if (!ret && oact) { + ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), + &oact->sa_handler); + ret |= put_compat_sigset(&oact->sa_mask, &old_ka.sa.sa_mask, + sizeof(oact->sa_mask)); + ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags); +#ifdef __ARCH_HAS_SA_RESTORER + ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer), + &oact->sa_restorer); +#endif + } + return ret; +} +#endif +#endif /* !CONFIG_ODD_RT_SIGACTION */ + +#ifdef CONFIG_OLD_SIGACTION +SYSCALL_DEFINE3(sigaction, int, sig, + const struct old_sigaction __user *, act, + struct old_sigaction __user *, oact) +{ + struct k_sigaction new_ka, old_ka; + int ret; + + if (act) { + old_sigset_t mask; + if (!access_ok(VERIFY_READ, act, sizeof(*act)) || + __get_user(new_ka.sa.sa_handler, &act->sa_handler) || + __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) || + __get_user(new_ka.sa.sa_flags, &act->sa_flags) || + __get_user(mask, &act->sa_mask)) + return -EFAULT; +#ifdef __ARCH_HAS_KA_RESTORER + new_ka.ka_restorer = NULL; +#endif + siginitset(&new_ka.sa.sa_mask, mask); + } + + ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); + + if (!ret && oact) { + if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) || + __put_user(old_ka.sa.sa_handler, &oact->sa_handler) || + __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) || + __put_user(old_ka.sa.sa_flags, &oact->sa_flags) || + __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask)) + return -EFAULT; + } + + return ret; +} +#endif +#ifdef CONFIG_COMPAT_OLD_SIGACTION +COMPAT_SYSCALL_DEFINE3(sigaction, int, sig, + const struct compat_old_sigaction __user *, act, + struct compat_old_sigaction __user *, oact) +{ + struct k_sigaction new_ka, old_ka; + int ret; + compat_old_sigset_t mask; + compat_uptr_t handler, restorer; + + if (act) { + if (!access_ok(VERIFY_READ, act, sizeof(*act)) || + __get_user(handler, &act->sa_handler) || + __get_user(restorer, &act->sa_restorer) || + __get_user(new_ka.sa.sa_flags, &act->sa_flags) || + __get_user(mask, &act->sa_mask)) + return -EFAULT; + +#ifdef __ARCH_HAS_KA_RESTORER + new_ka.ka_restorer = NULL; +#endif + new_ka.sa.sa_handler = compat_ptr(handler); + new_ka.sa.sa_restorer = compat_ptr(restorer); + siginitset(&new_ka.sa.sa_mask, mask); + } + + ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); + + if (!ret && oact) { + if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) || + __put_user(ptr_to_compat(old_ka.sa.sa_handler), + &oact->sa_handler) || + __put_user(ptr_to_compat(old_ka.sa.sa_restorer), + &oact->sa_restorer) || + __put_user(old_ka.sa.sa_flags, &oact->sa_flags) || + __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask)) + return -EFAULT; + } + return ret; +} +#endif + +#ifdef CONFIG_SGETMASK_SYSCALL + +/* + * For backwards compatibility. Functionality superseded by sigprocmask. + */ +SYSCALL_DEFINE0(sgetmask) +{ + /* SMP safe */ + return current->blocked.sig[0]; +} + +SYSCALL_DEFINE1(ssetmask, int, newmask) +{ + int old = current->blocked.sig[0]; + sigset_t newset; + + siginitset(&newset, newmask); + set_current_blocked(&newset); + + return old; +} +#endif /* CONFIG_SGETMASK_SYSCALL */ + +#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) +{ + while (!signal_pending(current)) { + __set_current_state(TASK_INTERRUPTIBLE); + schedule(); + } + return -ERESTARTNOHAND; +} + +#endif + +static int sigsuspend(sigset_t *set) +{ + current->saved_sigmask = current->blocked; + set_current_blocked(set); + + while (!signal_pending(current)) { + __set_current_state(TASK_INTERRUPTIBLE); + schedule(); + } + set_restore_sigmask(); + return -ERESTARTNOHAND; +} + +/** + * 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; + return sigsuspend(&newset); +} + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_size_t, sigsetsize) +{ + sigset_t newset; + + /* XXX: Don't preclude handling different sized sigset_t's. */ + if (sigsetsize != sizeof(sigset_t)) + return -EINVAL; + + if (get_compat_sigset(&newset, unewset)) + return -EFAULT; + return sigsuspend(&newset); +} +#endif + +#ifdef CONFIG_OLD_SIGSUSPEND +SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask) +{ + sigset_t blocked; + siginitset(&blocked, mask); + return sigsuspend(&blocked); +} +#endif +#ifdef CONFIG_OLD_SIGSUSPEND3 +SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask) +{ + sigset_t blocked; + siginitset(&blocked, mask); + return sigsuspend(&blocked); +} +#endif + +__weak const char *arch_vma_name(struct vm_area_struct *vma) +{ + return NULL; +} + +void __init signals_init(void) +{ + /* If this check fails, the __ARCH_SI_PREAMBLE_SIZE value is wrong! */ + BUILD_BUG_ON(__ARCH_SI_PREAMBLE_SIZE + != offsetof(struct siginfo, _sifields._pad)); + BUILD_BUG_ON(sizeof(struct siginfo) != SI_MAX_SIZE); + + sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC); +} + +#ifdef CONFIG_KGDB_KDB +#include <linux/kdb.h> +/* + * kdb_send_sig - 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(struct task_struct *t, int sig) +{ + static struct task_struct *kdb_prev_t; + int new_t, ret; + 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; + } + new_t = kdb_prev_t != t; + kdb_prev_t = t; + if (t->state != TASK_RUNNING && new_t) { + spin_unlock(&t->sighand->siglock); + 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; + } + ret = send_signal(sig, SEND_SIG_PRIV, t, PIDTYPE_PID); + spin_unlock(&t->sighand->siglock); + if (ret) + 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 */ |