pid namespaces: changes to show virtual ids to user

This is the largest patch in the set. Make all (I hope) the places where
the pid is shown to or get from user operate on the virtual pids.

The idea is:
 - all in-kernel data structures must store either struct pid itself
   or the pid's global nr, obtained with pid_nr() call;
 - when seeking the task from kernel code with the stored id one
   should use find_task_by_pid() call that works with global pids;
 - when showing pid's numerical value to the user the virtual one
   should be used, but however when one shows task's pid outside this
   task's namespace the global one is to be used;
 - when getting the pid from userspace one need to consider this as
   the virtual one and use appropriate task/pid-searching functions.

[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: nuther build fix]
[akpm@linux-foundation.org: yet nuther build fix]
[akpm@linux-foundation.org: remove unneeded casts]
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 20 insertions, 11 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 567909f..68d2703 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1112,15 +1112,17 @@ asmlinkage void sys_exit_group(int error_code)
 static int eligible_child(pid_t pid, int options, struct task_struct *p)
 {
 	int err;
+	struct pid_namespace *ns;
 
+	ns = current->nsproxy->pid_ns;
 	if (pid > 0) {
-		if (p->pid != pid)
+		if (task_pid_nr_ns(p, ns) != pid)
 			return 0;
 	} else if (!pid) {
-		if (task_pgrp_nr(p) != task_pgrp_nr(current))
+		if (task_pgrp_nr_ns(p, ns) != task_pgrp_vnr(current))
 			return 0;
 	} else if (pid != -1) {
-		if (task_pgrp_nr(p) != -pid)
+		if (task_pgrp_nr_ns(p, ns) != -pid)
 			return 0;
 	}
 
@@ -1190,9 +1192,12 @@ static int wait_task_zombie(struct task_struct *p, int noreap,
 {
 	unsigned long state;
 	int retval, status, traced;
+	struct pid_namespace *ns;
+
+	ns = current->nsproxy->pid_ns;
 
 	if (unlikely(noreap)) {
-		pid_t pid = p->pid;
+		pid_t pid = task_pid_nr_ns(p, ns);
 		uid_t uid = p->uid;
 		int exit_code = p->exit_code;
 		int why, status;
@@ -1311,11 +1316,11 @@ static int wait_task_zombie(struct task_struct *p, int noreap,
 			retval = put_user(status, &infop->si_status);
 	}
 	if (!retval && infop)
-		retval = put_user(p->pid, &infop->si_pid);
+		retval = put_user(task_pid_nr_ns(p, ns), &infop->si_pid);
 	if (!retval && infop)
 		retval = put_user(p->uid, &infop->si_uid);
 	if (!retval)
-		retval = p->pid;
+		retval = task_pid_nr_ns(p, ns);
 
 	if (traced) {
 		write_lock_irq(&tasklist_lock);
@@ -1352,6 +1357,7 @@ static int wait_task_stopped(struct task_struct *p, int delayed_group_leader,
 			     int __user *stat_addr, struct rusage __user *ru)
 {
 	int retval, exit_code;
+	struct pid_namespace *ns;
 
 	if (!p->exit_code)
 		return 0;
@@ -1370,11 +1376,12 @@ static int wait_task_stopped(struct task_struct *p, int delayed_group_leader,
 	 * keep holding onto the tasklist_lock while we call getrusage and
 	 * possibly take page faults for user memory.
 	 */
+	ns = current->nsproxy->pid_ns;
 	get_task_struct(p);
 	read_unlock(&tasklist_lock);
 
 	if (unlikely(noreap)) {
-		pid_t pid = p->pid;
+		pid_t pid = task_pid_nr_ns(p, ns);
 		uid_t uid = p->uid;
 		int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
 
@@ -1445,11 +1452,11 @@ bail_ref:
 	if (!retval && infop)
 		retval = put_user(exit_code, &infop->si_status);
 	if (!retval && infop)
-		retval = put_user(p->pid, &infop->si_pid);
+		retval = put_user(task_pid_nr_ns(p, ns), &infop->si_pid);
 	if (!retval && infop)
 		retval = put_user(p->uid, &infop->si_uid);
 	if (!retval)
-		retval = p->pid;
+		retval = task_pid_nr_ns(p, ns);
 	put_task_struct(p);
 
 	BUG_ON(!retval);
@@ -1469,6 +1476,7 @@ static int wait_task_continued(struct task_struct *p, int noreap,
 	int retval;
 	pid_t pid;
 	uid_t uid;
+	struct pid_namespace *ns;
 
 	if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
 		return 0;
@@ -1483,7 +1491,8 @@ static int wait_task_continued(struct task_struct *p, int noreap,
 		p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
 	spin_unlock_irq(&p->sighand->siglock);
 
-	pid = p->pid;
+	ns = current->nsproxy->pid_ns;
+	pid = task_pid_nr_ns(p, ns);
 	uid = p->uid;
 	get_task_struct(p);
 	read_unlock(&tasklist_lock);
@@ -1494,7 +1503,7 @@ static int wait_task_continued(struct task_struct *p, int noreap,
 		if (!retval && stat_addr)
 			retval = put_user(0xffff, stat_addr);
 		if (!retval)
-			retval = p->pid;
+			retval = task_pid_nr_ns(p, ns);
 	} else {
 		retval = wait_noreap_copyout(p, pid, uid,
 					     CLD_CONTINUED, SIGCONT,