[PATCH] Use find_task_by_pid_ns() in places that operate with virtualpids

[Pavel Emelyanov]

When the pid comes from the userspace, the find_task_by_pid_ns()
should be used to find the task by pid in particular (usually the
current) namespace. These places were lost in earlier patches.

Think over: all these places work like this:

	if (pid == 0)
		task = current;
	else
		task = find_task_by_pid_ns(pid);

the question is: does it worth introducing a common helper for such
case and (if it does) what should its name be?

Signed-off-by: Pavel Emelyanov <xemul@xxxxxxxxxx>
Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxxx>
Cc: Sukadev Bhattiprolu <sukadev@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>

---

This is a lost hunks of the -mm patch named
pid-namespaces-changes-to-show-virtual-ids-to-user.patch

fs/ioprio.c           |    6 ++++--
kernel/futex.c        |    6 ++++--
kernel/futex_compat.c |    3 ++-
kernel/sched.c        |    3 ++-
mm/mempolicy.c        |    3 ++-
mm/migrate.c          |    3 ++-
6 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/fs/ioprio.c b/fs/ioprio.c
index c99fe7b..0a615f8 100644
--- a/fs/ioprio.c
+++ b/fs/ioprio.c
@@ -94,7 +94,8 @@ asmlinkage long sys_ioprio_set(int which
			if (!who)
				p = current;
			else
-				p = find_task_by_pid(who);
+				p = find_task_by_pid_ns(who,
+						current->nsproxy->pid_ns);
			if (p)
				ret = set_task_ioprio(p, ioprio);
			break;
@@ -181,7 +182,8 @@ asmlinkage long sys_ioprio_get(int which
			if (!who)
				p = current;
			else
-				p = find_task_by_pid(who);
+				p = find_task_by_pid_ns(who,
+						current->nsproxy->pid_ns);
			if (p)
				ret = get_task_ioprio(p);
			break;
diff --git a/kernel/futex.c b/kernel/futex.c
index c61634a..0c1b777 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -444,7 +444,8 @@ static struct task_struct * futex_find_g
	struct task_struct *p;

	rcu_read_lock();
-	p = find_task_by_pid(pid);
+	p = find_task_by_pid_ns(pid,
+			current->nsproxy->pid_ns);

	if (!p || ((current->euid != p->euid) && (current->euid != p->uid)))
		p = ERR_PTR(-ESRCH);
@@ -1855,7 +1856,8 @@ sys_get_robust_list(int pid, struct robu

		ret = -ESRCH;
		rcu_read_lock();
-		p = find_task_by_pid(pid);
+		p = find_task_by_pid_ns(pid,
+				current->nsproxy->pid_ns);
		if (!p)
			goto err_unlock;
		ret = -EPERM;
diff --git a/kernel/futex_compat.c b/kernel/futex_compat.c
index f792136..e7563bf 100644
--- a/kernel/futex_compat.c
+++ b/kernel/futex_compat.c
@@ -116,7 +116,8 @@ compat_sys_get_robust_list(int pid, comp

		ret = -ESRCH;
		read_lock(&tasklist_lock);
-		p = find_task_by_pid(pid);
+		p = find_task_by_pid_ns(pid,
+				current->nsproxy->pid_ns);
		if (!p)
			goto err_unlock;
		ret = -EPERM;
diff --git a/kernel/sched.c b/kernel/sched.c
index 4359b6b..1f81803 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4108,7 +4108,8 @@ struct task_struct *idle_task(int cpu)
 */
static inline struct task_struct *find_process_by_pid(pid_t pid)
{
-	return pid ? find_task_by_pid(pid) : current;
+	return pid ?
+		find_task_by_pid_ns(pid, current->nsproxy->pid_ns) : current;
}

/* Actually do priority change: must hold rq lock. */
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index e7eb2bb..934abc9 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -930,7 +930,8 @@ asmlinkage long sys_migrate_pages(pid_t 

	/* Find the mm_struct */
	read_lock(&tasklist_lock);
-	task = pid ? find_task_by_pid(pid) : current;
+	task = pid ?
+		find_task_by_pid_ns(pid, current->nsproxy->pid_ns) : current;
	if (!task) {
		read_unlock(&tasklist_lock);
		return -ESRCH;
diff --git a/mm/migrate.c b/mm/migrate.c
index 477b894..7f43c5f 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -917,7 +917,8 @@ asmlinkage long sys_move_pages(pid_t pid

	/* Find the mm_struct */
	read_lock(&tasklist_lock);
-	task = pid ? find_task_by_pid(pid) : current;
+	task = pid ?
+		find_task_by_pid_ns(pid, current->nsproxy->pid_ns) : current;
	if (!task) {
		read_unlock(&tasklist_lock);
		return -ESRCH;
-
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