#include <linux/slab.h>
#include <linux/module.h>
-#include <linux/smp_lock.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/syscalls.h>
#include <linux/ptrace.h>
#include <linux/signal.h>
+#include <linux/signalfd.h>
#include <linux/capability.h>
#include <linux/freezer.h>
#include <linux/pid_namespace.h>
static struct kmem_cache *sigqueue_cachep;
-/*
- * In POSIX a signal is sent either to a specific thread (Linux task)
- * or to the process as a whole (Linux thread group). How the signal
- * is sent determines whether it's to one thread or the whole group,
- * which determines which signal mask(s) are involved in blocking it
- * from being delivered until later. When the signal is delivered,
- * either it's caught or ignored by a user handler or it has a default
- * effect that applies to the whole thread group (POSIX process).
- *
- * The possible effects an unblocked signal set to SIG_DFL can have are:
- * ignore - Nothing Happens
- * terminate - kill the process, i.e. all threads in the group,
- * similar to exit_group. The group leader (only) reports
- * WIFSIGNALED status to its parent.
- * coredump - write a core dump file describing all threads using
- * the same mm and then kill all those threads
- * stop - stop all the threads in the group, i.e. TASK_STOPPED state
- *
- * SIGKILL and SIGSTOP cannot be caught, blocked, or ignored.
- * Other signals when not blocked and set to SIG_DFL behaves as follows.
- * The job control signals also have other special effects.
- *
- * +--------------------+------------------+
- * | POSIX signal | default action |
- * +--------------------+------------------+
- * | SIGHUP | terminate |
- * | SIGINT | terminate |
- * | SIGQUIT | coredump |
- * | SIGILL | coredump |
- * | SIGTRAP | coredump |
- * | SIGABRT/SIGIOT | coredump |
- * | SIGBUS | coredump |
- * | SIGFPE | coredump |
- * | SIGKILL | terminate(+) |
- * | SIGUSR1 | terminate |
- * | SIGSEGV | coredump |
- * | SIGUSR2 | terminate |
- * | SIGPIPE | terminate |
- * | SIGALRM | terminate |
- * | SIGTERM | terminate |
- * | SIGCHLD | ignore |
- * | SIGCONT | ignore(*) |
- * | SIGSTOP | stop(*)(+) |
- * | SIGTSTP | stop(*) |
- * | SIGTTIN | stop(*) |
- * | SIGTTOU | stop(*) |
- * | SIGURG | ignore |
- * | SIGXCPU | coredump |
- * | SIGXFSZ | coredump |
- * | SIGVTALRM | terminate |
- * | SIGPROF | terminate |
- * | SIGPOLL/SIGIO | terminate |
- * | SIGSYS/SIGUNUSED | coredump |
- * | SIGSTKFLT | terminate |
- * | SIGWINCH | ignore |
- * | SIGPWR | terminate |
- * | SIGRTMIN-SIGRTMAX | terminate |
- * +--------------------+------------------+
- * | non-POSIX signal | default action |
- * +--------------------+------------------+
- * | SIGEMT | coredump |
- * +--------------------+------------------+
- *
- * (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
- * (*) Special job control effects:
- * When SIGCONT is sent, it resumes the process (all threads in the group)
- * from TASK_STOPPED state and also clears any pending/queued stop signals
- * (any of those marked with "stop(*)"). This happens regardless of blocking,
- * catching, or ignoring SIGCONT. When any stop signal is sent, it clears
- * any pending/queued SIGCONT signals; this happens regardless of blocking,
- * catching, or ignored the stop signal, though (except for SIGSTOP) the
- * default action of stopping the process may happen later or never.
- */
-
-#ifdef SIGEMT
-#define M_SIGEMT M(SIGEMT)
-#else
-#define M_SIGEMT 0
-#endif
-
-#if SIGRTMIN > BITS_PER_LONG
-#define M(sig) (1ULL << ((sig)-1))
-#else
-#define M(sig) (1UL << ((sig)-1))
-#endif
-#define T(sig, mask) (M(sig) & (mask))
-
-#define SIG_KERNEL_ONLY_MASK (\
- M(SIGKILL) | M(SIGSTOP) )
-
-#define SIG_KERNEL_STOP_MASK (\
- M(SIGSTOP) | M(SIGTSTP) | M(SIGTTIN) | M(SIGTTOU) )
-
-#define SIG_KERNEL_COREDUMP_MASK (\
- M(SIGQUIT) | M(SIGILL) | M(SIGTRAP) | M(SIGABRT) | \
- M(SIGFPE) | M(SIGSEGV) | M(SIGBUS) | M(SIGSYS) | \
- M(SIGXCPU) | M(SIGXFSZ) | M_SIGEMT )
-
-#define SIG_KERNEL_IGNORE_MASK (\
- M(SIGCONT) | M(SIGCHLD) | M(SIGWINCH) | M(SIGURG) )
-
-#define sig_kernel_only(sig) \
- (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_ONLY_MASK))
-#define sig_kernel_coredump(sig) \
- (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_COREDUMP_MASK))
-#define sig_kernel_ignore(sig) \
- (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_IGNORE_MASK))
-#define sig_kernel_stop(sig) \
- (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_STOP_MASK))
-
-#define sig_needs_tasklist(sig) ((sig) == SIGCONT)
-
-#define sig_user_defined(t, signr) \
- (((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) && \
- ((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN))
-
-#define sig_fatal(t, signr) \
- (!T(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \
- (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL)
static int sig_ignored(struct task_struct *t, int sig)
{
#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
-fastcall void recalc_sigpending_tsk(struct task_struct *t)
+static int recalc_sigpending_tsk(struct task_struct *t)
{
if (t->signal->group_stop_count > 0 ||
(freezing(t)) ||
PENDING(&t->pending, &t->blocked) ||
- PENDING(&t->signal->shared_pending, &t->blocked))
+ PENDING(&t->signal->shared_pending, &t->blocked)) {
set_tsk_thread_flag(t, TIF_SIGPENDING);
- else
- clear_tsk_thread_flag(t, TIF_SIGPENDING);
+ return 1;
+ }
+ clear_tsk_thread_flag(t, TIF_SIGPENDING);
+ return 0;
+}
+
+/*
+ * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
+ * This is superfluous when called on current, the wakeup is a harmless no-op.
+ */
+void recalc_sigpending_and_wake(struct task_struct *t)
+{
+ if (recalc_sigpending_tsk(t))
+ signal_wake_up(t, 0);
}
void recalc_sigpending(void)
/* Given the mask, find the first available signal that should be serviced. */
-static int
-next_signal(struct sigpending *pending, sigset_t *mask)
+int next_signal(struct sigpending *pending, sigset_t *mask)
{
unsigned long i, *s, *m, x;
int sig = 0;
spin_unlock_irqrestore(&t->sighand->siglock, flags);
}
+void ignore_signals(struct task_struct *t)
+{
+ int i;
+
+ for (i = 0; i < _NSIG; ++i)
+ t->sighand->action[i].sa.sa_handler = SIG_IGN;
+
+ flush_signals(t);
+}
+
/*
* Flush all handlers for a task.
*/
int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
{
int signr = __dequeue_signal(&tsk->pending, mask, info);
- if (!signr)
+ if (!signr) {
signr = __dequeue_signal(&tsk->signal->shared_pending,
mask, info);
+ /*
+ * itimer signal ?
+ *
+ * itimers are process shared and we restart periodic
+ * itimers in the signal delivery path to prevent DoS
+ * attacks in the high resolution timer case. This is
+ * compliant with the old way of self restarting
+ * itimers, as the SIGALRM is a legacy signal and only
+ * queued once. Changing the restart behaviour to
+ * restart the timer in the signal dequeue path is
+ * reducing the timer noise on heavy loaded !highres
+ * systems too.
+ */
+ if (unlikely(signr == SIGALRM)) {
+ struct hrtimer *tmr = &tsk->signal->real_timer;
+
+ if (!hrtimer_is_queued(tmr) &&
+ tsk->signal->it_real_incr.tv64 != 0) {
+ hrtimer_forward(tmr, tmr->base->get_time(),
+ tsk->signal->it_real_incr);
+ hrtimer_restart(tmr);
+ }
+ }
+ }
recalc_sigpending_tsk(tsk);
- if (signr && 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.
- */
- if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
- tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
- }
+ if (signr && 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.
+ */
+ if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
+ tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
+ }
if ( signr &&
((info->si_code & __SI_MASK) == __SI_TIMER) &&
info->si_sys_private){
int error = -EINVAL;
if (!valid_signal(sig))
return error;
+
+ error = audit_signal_info(sig, t); /* Let audit system see the signal */
+ if (error)
+ return error;
+
error = -EPERM;
if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
&& ((sig != SIGCONT) ||
&& !capable(CAP_KILL))
return error;
- error = security_task_kill(t, info, sig, 0);
- if (!error)
- audit_signal_info(sig, t); /* Let audit system see the signal */
- return error;
+ return security_task_kill(t, info, sig, 0);
}
/* forward decl */
struct sigqueue * q = NULL;
int ret = 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.
action->sa.sa_handler = SIG_DFL;
if (blocked) {
sigdelset(&t->blocked, sig);
- recalc_sigpending_tsk(t);
+ recalc_sigpending_and_wake(t);
}
}
ret = specific_send_sig_info(sig, info, t);
if (t->exit_state)
continue;
- /*
- * We don't want to notify the parent, since we are
- * killed as part of a thread group due to another
- * thread doing an execve() or similar. So set the
- * exit signal to -1 to allow immediate reaping of
- * the process. But don't detach the thread group
- * leader.
- */
- if (t != p->group_leader)
- t->exit_signal = -1;
-
/* SIGKILL will be handled before any pending SIGSTOP */
sigaddset(&t->pending.signal, SIGKILL);
signal_wake_up(t, 1);
return retval;
}
-int __kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
-{
- if (pgrp <= 0)
- return -EINVAL;
-
- return __kill_pgrp_info(sig, info, find_pid(pgrp));
-}
-
-int
-kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
-{
- int retval;
-
- read_lock(&tasklist_lock);
- retval = __kill_pg_info(sig, info, pgrp);
- read_unlock(&tasklist_lock);
-
- return retval;
-}
-
int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
{
int error;
- int acquired_tasklist_lock = 0;
struct task_struct *p;
rcu_read_lock();
- if (unlikely(sig_needs_tasklist(sig))) {
+ if (unlikely(sig_needs_tasklist(sig)))
read_lock(&tasklist_lock);
- acquired_tasklist_lock = 1;
- }
+
p = pid_task(pid, PIDTYPE_PID);
error = -ESRCH;
if (p)
error = group_send_sig_info(sig, info, p);
- if (unlikely(acquired_tasklist_lock))
+
+ if (unlikely(sig_needs_tasklist(sig)))
read_unlock(&tasklist_lock);
rcu_read_unlock();
return error;
}
-static int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
+int
+kill_proc_info(int sig, struct siginfo *info, pid_t pid)
{
int error;
rcu_read_lock();
static int kill_something_info(int sig, struct siginfo *info, int pid)
{
+ int ret;
+ rcu_read_lock();
if (!pid) {
- return kill_pg_info(sig, info, process_group(current));
+ ret = kill_pgrp_info(sig, info, task_pgrp(current));
} else if (pid == -1) {
int retval = 0, count = 0;
struct task_struct * p;
}
}
read_unlock(&tasklist_lock);
- return count ? retval : -ESRCH;
+ ret = count ? retval : -ESRCH;
} else if (pid < 0) {
- return kill_pg_info(sig, info, -pid);
+ ret = kill_pgrp_info(sig, info, find_pid(-pid));
} else {
- return kill_proc_info(sig, info, pid);
+ ret = kill_pid_info(sig, info, find_pid(pid));
}
+ rcu_read_unlock();
+ return ret;
}
/*
}
EXPORT_SYMBOL(kill_pid);
-int
-kill_pg(pid_t pgrp, int sig, int priv)
-{
- return kill_pg_info(sig, __si_special(priv), pgrp);
-}
-
int
kill_proc(pid_t pid, int sig, int priv)
{
ret = 1;
goto out;
}
+ /*
+ * Deliver the signal to listening signalfds. This must be called
+ * with the sighand lock held.
+ */
+ signalfd_notify(p, sig);
list_add_tail(&q->list, &p->pending.list);
sigaddset(&p->pending.signal, sig);
q->info.si_overrun++;
goto out;
}
+ /*
+ * Deliver the signal to listening signalfds. This must be called
+ * with the sighand lock held.
+ */
+ signalfd_notify(p, sig);
/*
* Put this signal on the shared-pending queue.
/* signals can be posted during this window */
- if (is_orphaned_pgrp(process_group(current)))
+ if (is_current_pgrp_orphaned())
goto relock;
spin_lock_irq(¤t->sighand->siglock);
EXPORT_SYMBOL_GPL(dequeue_signal);
EXPORT_SYMBOL(flush_signals);
EXPORT_SYMBOL(force_sig);
-EXPORT_SYMBOL(kill_pg);
EXPORT_SYMBOL(kill_proc);
EXPORT_SYMBOL(ptrace_notify);
EXPORT_SYMBOL(send_sig);
/*
* If you change siginfo_t structure, please be sure
* this code is fixed accordingly.
+ * Please remember to update the signalfd_copyinfo() function
+ * inside fs/signalfd.c too, in case siginfo_t changes.
* It should never copy any pad contained in the structure
* to avoid security leaks, but must copy the generic
* 3 ints plus the relevant union member.
* @pid: the PID of the thread
* @sig: signal to be sent
*
- * This syscall also checks the tgid and returns -ESRCH even if the PID
+ * 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.
*/
rm_from_queue_full(&mask, &t->signal->shared_pending);
do {
rm_from_queue_full(&mask, &t->pending);
- recalc_sigpending_tsk(t);
+ recalc_sigpending_and_wake(t);
t = next_thread(t);
} while (t != current);
}
void __init signals_init(void)
{
- sigqueue_cachep =
- kmem_cache_create("sigqueue",
- sizeof(struct sigqueue),
- __alignof__(struct sigqueue),
- SLAB_PANIC, NULL, NULL);
+ sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
}
projects / linux-drm-fsl-dcu.git / blobdiff