static int check_kill_permission(int sig, struct siginfo *info,
struct task_struct *t)
{
+ struct pid *sid;
int error;
if (!valid_signal(sig))
if (error)
return error;
- if (((sig != SIGCONT) || (task_session_nr(current) != task_session_nr(t)))
- && (current->euid ^ t->suid) && (current->euid ^ t->uid)
- && (current->uid ^ t->suid) && (current->uid ^ t->uid)
- && !capable(CAP_KILL))
- return -EPERM;
+ if ((current->euid ^ t->suid) && (current->euid ^ t->uid) &&
+ (current->uid ^ t->suid) && (current->uid ^ t->uid) &&
+ !capable(CAP_KILL)) {
+ switch (sig) {
+ case SIGCONT:
+ sid = task_session(t);
+ /*
+ * We don't return the error if sid == NULL. The
+ * task was unhashed, the caller must notice this.
+ */
+ if (!sid || sid == task_session(current))
+ break;
+ default:
+ return -EPERM;
+ }
+ }
return security_task_kill(t, info, sig, 0);
}
static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
/*
- * Handle magic process-wide effects of stop/continue signals.
- * Unlike the signal actions, these happen immediately at signal-generation
+ * 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.
+ * 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 void handle_stop_signal(int sig, struct task_struct *p)
+static int prepare_signal(int sig, struct task_struct *p)
{
struct signal_struct *signal = p->signal;
struct task_struct *t;
- if (signal->flags & SIGNAL_GROUP_EXIT)
+ if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
/*
- * The process is in the middle of dying already.
+ * The process is in the middle of dying, nothing to do.
*/
- return;
-
- if (sig_kernel_stop(sig)) {
+ } else if (sig_kernel_stop(sig)) {
/*
* This is a stop signal. Remove SIGCONT from all queues.
*/
why |= SIGNAL_CLD_STOPPED;
if (why) {
+ /*
+ * The first thread which returns from finish_stop()
+ * will take ->siglock, notice SIGNAL_CLD_MASK, and
+ * notify its parent. See get_signal_to_deliver().
+ */
signal->flags = why | SIGNAL_STOP_CONTINUED;
signal->group_stop_count = 0;
signal->group_exit_code = 0;
*/
signal->flags &= ~SIGNAL_STOP_DEQUEUED;
}
- } else if (sig == SIGKILL) {
- /*
- * Make sure that any pending stop signal already dequeued
- * is undone by the wakeup for SIGKILL.
- */
- signal->flags &= ~SIGNAL_STOP_DEQUEUED;
}
+
+ return !sig_ignored(p, sig);
}
/*
return task_curr(p) || !signal_pending(p);
}
-static void
-__group_complete_signal(int sig, struct task_struct *p)
+static void complete_signal(int sig, struct task_struct *p, int group)
{
struct signal_struct *signal = p->signal;
struct task_struct *t;
*/
if (wants_signal(sig, p))
t = p;
- else if (thread_group_empty(p))
+ else if (!group || thread_group_empty(p))
/*
* There is just one thread and it does not need to be woken.
* It will dequeue unblocked signals before it runs again.
* 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) &&
+ if (sig_fatal(p, sig) &&
+ !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
!sigismember(&t->real_blocked, sig) &&
(sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
/*
}
static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
- struct sigpending *signals)
+ int group)
{
+ struct sigpending *pending;
struct sigqueue *q;
assert_spin_locked(&t->sighand->siglock);
- handle_stop_signal(sig, t);
+ if (!prepare_signal(sig, t))
+ return 0;
+
+ pending = group ? &t->signal->shared_pending : &t->pending;
/*
* Short-circuit ignored signals and support queuing
* exactly one non-rt signal, so that we can get more
* detailed information about the cause of the signal.
*/
- if (sig_ignored(t, sig) || legacy_queue(signals, sig))
+ if (legacy_queue(pending, sig))
return 0;
-
- /*
- * Deliver the signal to listening signalfds. This must be called
- * with the sighand lock held.
- */
- signalfd_notify(t, sig);
-
/*
* fast-pathed signals for kernel-internal things like SIGSTOP
* or SIGKILL.
(is_si_special(info) ||
info->si_code >= 0)));
if (q) {
- list_add_tail(&q->list, &signals->list);
+ list_add_tail(&q->list, &pending->list);
switch ((unsigned long) info) {
case (unsigned long) SEND_SIG_NOINFO:
q->info.si_signo = sig;
}
out_set:
- sigaddset(&signals->signal, sig);
- return 1;
+ signalfd_notify(t, sig);
+ sigaddset(&pending->signal, sig);
+ complete_signal(sig, t, group);
+ return 0;
}
int print_fatal_signals;
__setup("print-fatal-signals=", setup_print_fatal_signals);
+int
+__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
+{
+ return send_signal(sig, info, p, 1);
+}
+
static int
specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{
- int ret;
-
- ret = send_signal(sig, info, t, &t->pending);
- if (ret <= 0)
- return ret;
-
- if (!sigismember(&t->blocked, sig))
- signal_wake_up(t, sig == SIGKILL);
- return 0;
+ return send_signal(sig, info, t, 0);
}
/*
* 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.
+ * 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)
recalc_sigpending_and_wake(t);
}
}
+ if (action->sa.sa_handler == SIG_DFL)
+ t->signal->flags &= ~SIGNAL_UNKILLABLE;
ret = specific_send_sig_info(sig, info, t);
spin_unlock_irqrestore(&t->sighand->siglock, flags);
force_sig_info(sig, SEND_SIG_FORCED, t);
}
-int
-__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
-{
- int ret;
-
- /*
- * Put this signal on the shared-pending queue, or fail with EAGAIN.
- * We always use the shared queue for process-wide signals,
- * to avoid several races.
- */
- ret = send_signal(sig, info, p, &p->signal->shared_pending);
- if (ret <= 0)
- return ret;
-
- __group_complete_signal(sig, p);
- return 0;
-}
-
/*
* Nuke all other threads in the group.
*/
__sigqueue_free(q);
}
-static int do_send_sigqueue(int sig, struct sigqueue *q, struct task_struct *t,
- struct sigpending *pending)
+int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
{
- handle_stop_signal(sig, t);
+ int sig = q->info.si_signo;
+ struct sigpending *pending;
+ unsigned long flags;
+ int ret;
+
+ BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
+
+ ret = -1;
+ if (!likely(lock_task_sighand(t, &flags)))
+ goto ret;
+ ret = 1; /* the signal is ignored */
+ if (!prepare_signal(sig, t))
+ 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++;
- return 0;
+ goto out;
}
- if (sig_ignored(t, sig))
- return 1;
-
signalfd_notify(t, sig);
+ pending = group ? &t->signal->shared_pending : &t->pending;
list_add_tail(&q->list, &pending->list);
sigaddset(&pending->signal, sig);
- return 0;
-}
-
-int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
-{
- unsigned long flags;
- int ret = -1;
-
- BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
-
- /*
- * The rcu based delayed sighand destroy makes it possible to
- * run this without tasklist lock held. The task struct itself
- * cannot go away as create_timer did get_task_struct().
- *
- * We return -1, when the task is marked exiting, so
- * posix_timer_event can redirect it to the group leader
- */
- if (!likely(lock_task_sighand(p, &flags)))
- goto out_err;
-
- ret = do_send_sigqueue(sig, q, p, &p->pending);
-
- if (!sigismember(&p->blocked, sig))
- signal_wake_up(p, sig == SIGKILL);
-
- unlock_task_sighand(p, &flags);
-out_err:
- return ret;
-}
-
-int
-send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
-{
- unsigned long flags;
- int ret;
-
- BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
-
- /* Since it_lock is held, p->sighand cannot be NULL. */
- spin_lock_irqsave(&p->sighand->siglock, flags);
-
- ret = do_send_sigqueue(sig, q, p, &p->signal->shared_pending);
-
- __group_complete_signal(sig, p);
-
- spin_unlock_irqrestore(&p->sighand->siglock, flags);
-
+ complete_signal(sig, t, group);
+out:
+ unlock_task_sighand(t, &flags);
+ret:
return ret;
}
} else {
struct task_struct *t;
- if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
+ if (unlikely((sig->flags & (SIGNAL_STOP_DEQUEUED | SIGNAL_UNKILLABLE))
+ != SIGNAL_STOP_DEQUEUED) ||
unlikely(signal_group_exit(sig)))
return 0;
/*
try_to_freeze();
spin_lock_irq(&sighand->siglock);
-
+ /*
+ * Every stopped thread goes here after wakeup. Check to see if
+ * we should notify the parent, prepare_signal(SIGCONT) encodes
+ * the CLD_ si_code into SIGNAL_CLD_MASK bits.
+ */
if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
int why = (signal->flags & SIGNAL_STOP_CONTINUED)
? CLD_CONTINUED : CLD_STOPPED;
/*
* Global init gets no signals it doesn't want.
*/
- if (is_global_init(current))
+ if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
+ !signal_group_exit(signal))
continue;
if (sig_kernel_stop(signr)) {
* Anything else is fatal, maybe with a core dump.
*/
current->flags |= PF_SIGNALED;
- if ((signr != SIGKILL) && print_fatal_signals)
- print_fatal_signal(regs, signr);
+
if (sig_kernel_coredump(signr)) {
+ if (print_fatal_signals)
+ print_fatal_signal(regs, signr);
/*
* If it was able to dump core, this kills all
* other threads in the group and synchronizes with
current->state = TASK_INTERRUPTIBLE;
schedule();
- set_thread_flag(TIF_RESTORE_SIGMASK);
+ set_restore_sigmask();
return -ERESTARTNOHAND;
}
#endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */