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, 8 insertions, 6 deletions

diff --git a/kernel/capability.c b/kernel/capability.c
index f02ad47320b..d4377c5a36c 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -62,8 +62,9 @@ asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
 	spin_lock(&task_capability_lock);
 	read_lock(&tasklist_lock);
 
-	if (pid && pid != current->pid) {
-		target = find_task_by_pid(pid);
+	if (pid && pid != task_pid_vnr(current)) {
+		target = find_task_by_pid_ns(pid,
+				current->nsproxy->pid_ns);
 		if (!target) {
 			ret = -ESRCH;
 			goto out;
@@ -96,7 +97,7 @@ static inline int cap_set_pg(int pgrp_nr, kernel_cap_t *effective,
 	int found = 0;
 	struct pid *pgrp;
 
-	pgrp = find_pid(pgrp_nr);
+	pgrp = find_pid_ns(pgrp_nr, current->nsproxy->pid_ns);
 	do_each_pid_task(pgrp, PIDTYPE_PGID, g) {
 		target = g;
 		while_each_thread(g, target) {
@@ -185,7 +186,7 @@ asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
 	if (get_user(pid, &header->pid))
 		return -EFAULT;
 
-	if (pid && pid != current->pid && !capable(CAP_SETPCAP))
+	if (pid && pid != task_pid_vnr(current) && !capable(CAP_SETPCAP))
 		return -EPERM;
 
 	if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
@@ -196,8 +197,9 @@ asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
 	spin_lock(&task_capability_lock);
 	read_lock(&tasklist_lock);
 
-	if (pid > 0 && pid != current->pid) {
-		target = find_task_by_pid(pid);
+	if (pid > 0 && pid != task_pid_vnr(current)) {
+		target = find_task_by_pid_ns(pid,
+				current->nsproxy->pid_ns);
 		if (!target) {
 			ret = -ESRCH;
 			goto out;