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Commit 35de254d authored by Roland McGrath's avatar Roland McGrath Committed by Linus Torvalds
Browse files

tracehook: tracehook_consider_ignored_signal 



This defines tracehook_consider_ignored_signal() has a fine-grained hook
for deciding to prevent the normal short-circuit of sending an ignored
signal, as ptrace does.  There is no change, only cleanup.

Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Reviewed-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c45aea27

include/linux/tracehook.h

+19 −0
Original line number Diff line number Diff line
@@ -312,4 +312,23 @@ static inline void tracehook_signal_handler(int sig, siginfo_t *info, 
		ptrace_notify(SIGTRAP);

}



/**

 * tracehook_consider_ignored_signal - suppress short-circuit of ignored signal

 * @task:		task receiving the signal

 * @sig:		signal number being sent

 * @handler:		%SIG_IGN or %SIG_DFL

 *

 * Return zero iff tracing doesn't care to examine this ignored signal,

 * so it can short-circuit normal delivery and never even get queued.

 * Either @handler is %SIG_DFL and @sig's default is ignore, or it's %SIG_IGN.

 *

 * Called with @task->sighand->siglock held.

 */

static inline int tracehook_consider_ignored_signal(struct task_struct *task,

						    int sig,

						    void __user *handler)

{

	return (task_ptrace(task) & PT_PTRACED) != 0;

}



#endif	/* <linux/tracehook.h> */

kernel/signal.c

+16 −11
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <linux/ptrace.h>

#include <linux/signal.h>

#include <linux/signalfd.h>

#include <linux/tracehook.h>

#include <linux/capability.h>

#include <linux/freezer.h>

#include <linux/pid_namespace.h>
@@ -39,24 +40,21 @@ 


static struct kmem_cache *sigqueue_cachep;



static int __sig_ignored(struct task_struct *t, int sig)

static void __user *sig_handler(struct task_struct *t, int sig)

{

	void __user *handler;

	return t->sighand->action[sig - 1].sa.sa_handler;

}



static int sig_handler_ignored(void __user *handler, int sig)

{

	/* Is it explicitly or implicitly ignored? */



	handler = t->sighand->action[sig - 1].sa.sa_handler;

	return handler == SIG_IGN ||

		(handler == SIG_DFL && sig_kernel_ignore(sig));

}



static int sig_ignored(struct task_struct *t, int sig)

{

	/*

	 * Tracers always want to know about signals..

	 */

	if (t->ptrace & PT_PTRACED)

		return 0;

	void __user *handler;



	/*

	 * Blocked signals are never ignored, since the
@@ -66,7 +64,14 @@ static int sig_ignored(struct task_struct *t, int sig) 
	if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))

		return 0;



	return __sig_ignored(t, sig);

	handler = sig_handler(t, sig);

	if (!sig_handler_ignored(handler, sig))

		return 0;



	/*

	 * Tracers may want to know about even ignored signals.

	 */

	return !tracehook_consider_ignored_signal(t, sig, handler);

}



/*
@@ -2298,7 +2303,7 @@ int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) 
		 *   (for example, SIGCHLD), shall cause the pending signal to

		 *   be discarded, whether or not it is blocked"

		 */

		if (__sig_ignored(t, sig)) {

		if (sig_handler_ignored(sig_handler(t, sig), sig)) {

			sigemptyset(&mask);

			sigaddset(&mask, sig);

			rm_from_queue_full(&mask, &t->signal->shared_pending);