Commit bac0abd6 authored by Pavel Emelyanov's avatar Pavel Emelyanov Committed by Linus Torvalds
Browse files

Isolate some explicit usage of task->tgid 



With pid namespaces this field is now dangerous to use explicitly, so hide
it behind the helpers.

Also the pid and pgrp fields o task_struct and signal_struct are to be
deprecated.  Unfortunately this patch cannot be sent right now as this
leads to tons of warnings, so start isolating them, and deprecate later.

Actually the p->tgid == pid has to be changed to has_group_leader_pid(),
but Oleg pointed out that in case of posix cpu timers this is the same, and
thread_group_leader() is more preferable.

Signed-off-by: default avatarPavel Emelyanov <xemul@openvz.org>
Acked-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 19b9b9b5

fs/exec.c

+2 −2
Original line number Diff line number Diff line
@@ -841,8 +841,8 @@ static int de_thread(struct task_struct *tsk) 
		 */

		tsk->start_time = leader->start_time;



		BUG_ON(leader->tgid != tsk->tgid);

		BUG_ON(tsk->pid == tsk->tgid);

		BUG_ON(!same_thread_group(leader, tsk));

		BUG_ON(has_group_leader_pid(tsk));

		/*

		 * An exec() starts a new thread group with the

		 * TGID of the previous thread group. Rehash the

fs/proc/base.c

+1 −1
Original line number Diff line number Diff line
@@ -2553,7 +2553,7 @@ static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry 
	rcu_read_unlock();

	if (!task)

		goto out;

	if (leader->tgid != task->tgid)

	if (!same_thread_group(leader, task))

		goto out_drop_task;



	result = proc_task_instantiate(dir, dentry, task, NULL);

include/linux/sched.h

+6 −0
Original line number Diff line number Diff line
@@ -1725,6 +1725,12 @@ static inline int has_group_leader_pid(struct task_struct *p) 
	return p->pid == p->tgid;

}



static inline

int same_thread_group(struct task_struct *p1, struct task_struct *p2)

{

	return p1->tgid == p2->tgid;

}



static inline struct task_struct *next_thread(const struct task_struct *p)

{

	return list_entry(rcu_dereference(p->thread_group.next),

kernel/posix-cpu-timers.c

+6 −6
Original line number Diff line number Diff line
@@ -21,8 +21,8 @@ static int check_clock(const clockid_t which_clock) 


	read_lock(&tasklist_lock);

	p = find_task_by_pid(pid);

	if (!p || (CPUCLOCK_PERTHREAD(which_clock) ?

		   p->tgid != current->tgid : p->tgid != pid)) {

	if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?

		   same_thread_group(p, current) : thread_group_leader(p))) {

		error = -EINVAL;

	}

	read_unlock(&tasklist_lock);
@@ -308,13 +308,13 @@ int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp) 
		p = find_task_by_pid(pid);

		if (p) {

			if (CPUCLOCK_PERTHREAD(which_clock)) {

				if (p->tgid == current->tgid) {

				if (same_thread_group(p, current)) {

					error = cpu_clock_sample(which_clock,

								 p, &rtn);

				}

			} else {

				read_lock(&tasklist_lock);

				if (p->tgid == pid && p->signal) {

				if (thread_group_leader(p) && p->signal) {

					error =

					    cpu_clock_sample_group(which_clock,

							           p, &rtn);
@@ -355,7 +355,7 @@ int posix_cpu_timer_create(struct k_itimer *new_timer) 
			p = current;

		} else {

			p = find_task_by_pid(pid);

			if (p && p->tgid != current->tgid)

			if (p && !same_thread_group(p, current))

				p = NULL;

		}

	} else {
@@ -363,7 +363,7 @@ int posix_cpu_timer_create(struct k_itimer *new_timer) 
			p = current->group_leader;

		} else {

			p = find_task_by_pid(pid);

			if (p && p->tgid != pid)

			if (p && !thread_group_leader(p))

				p = NULL;

		}

	}

kernel/posix-timers.c

+2 −2
Original line number Diff line number Diff line
@@ -404,7 +404,7 @@ static struct task_struct * good_sigevent(sigevent_t * event) 


	if ((event->sigev_notify & SIGEV_THREAD_ID ) &&

		(!(rtn = find_task_by_pid(event->sigev_notify_thread_id)) ||

		 rtn->tgid != current->tgid ||

		 !same_thread_group(rtn, current) ||

		 (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL))

		return NULL;
@@ -608,7 +608,7 @@ static struct k_itimer * lock_timer(timer_t timer_id, unsigned long *flags) 
		spin_lock(&timr->it_lock);



		if ((timr->it_id != timer_id) || !(timr->it_process) ||

				timr->it_process->tgid != current->tgid) {

				!same_thread_group(timr->it_process, current)) {

			spin_unlock(&timr->it_lock);

			spin_unlock_irqrestore(&idr_lock, *flags);

			timr = NULL;

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