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, 16 insertions, 11 deletions

diff --git a/kernel/futex.c b/kernel/futex.c
index e45a65e41686..86b2600381b6 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -53,6 +53,9 @@
 #include <linux/signal.h>
 #include <linux/module.h>
 #include <linux/magic.h>
+#include <linux/pid.h>
+#include <linux/nsproxy.h>
+
 #include <asm/futex.h>
 
 #include "rtmutex_common.h"
@@ -443,7 +446,8 @@ static struct task_struct * futex_find_get_task(pid_t pid)
         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);
@@ -653,7 +657,7 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this)
         if (!(uval & FUTEX_OWNER_DIED)) {
                 int ret = 0;
 
-                newval = FUTEX_WAITERS | new_owner->pid;
+                newval = FUTEX_WAITERS | task_pid_vnr(new_owner);
 
                 curval = cmpxchg_futex_value_locked(uaddr, uval, newval);
 
@@ -1106,7 +1110,7 @@ static void unqueue_me_pi(struct futex_q *q)
 static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
                                 struct task_struct *curr)
 {
-        u32 newtid = curr->pid | FUTEX_WAITERS;
+        u32 newtid = task_pid_vnr(curr) | FUTEX_WAITERS;
         struct futex_pi_state *pi_state = q->pi_state;
         u32 uval, curval, newval;
         int ret;
@@ -1368,7 +1372,7 @@ static int futex_lock_pi(u32 __user *uaddr, struct rw_semaphore *fshared,
          * (by doing a 0 -> TID atomic cmpxchg), while holding all
          * the locks. It will most likely not succeed.
          */
-        newval = current->pid;
+        newval = task_pid_vnr(current);
 
         curval = cmpxchg_futex_value_locked(uaddr, 0, newval);
 
@@ -1379,7 +1383,7 @@ static int futex_lock_pi(u32 __user *uaddr, struct rw_semaphore *fshared,
          * Detect deadlocks. In case of REQUEUE_PI this is a valid
          * situation and we return success to user space.
          */
-        if (unlikely((curval & FUTEX_TID_MASK) == current->pid)) {
+        if (unlikely((curval & FUTEX_TID_MASK) == task_pid_vnr(current))) {
                 ret = -EDEADLK;
                 goto out_unlock_release_sem;
         }
@@ -1408,7 +1412,7 @@ static int futex_lock_pi(u32 __user *uaddr, struct rw_semaphore *fshared,
          */
         if (unlikely(ownerdied || !(curval & FUTEX_TID_MASK))) {
                 /* Keep the OWNER_DIED bit */
-                newval = (curval & ~FUTEX_TID_MASK) | current->pid;
+                newval = (curval & ~FUTEX_TID_MASK) | task_pid_vnr(current);
                 ownerdied = 0;
                 lock_taken = 1;
         }
@@ -1587,7 +1591,7 @@ retry:
         /*
          * We release only a lock we actually own:
          */
-        if ((uval & FUTEX_TID_MASK) != current->pid)
+        if ((uval & FUTEX_TID_MASK) != task_pid_vnr(current))
                 return -EPERM;
         /*
          * First take all the futex related locks:
@@ -1608,7 +1612,7 @@ retry_unlocked:
          * anyone else up:
          */
         if (!(uval & FUTEX_OWNER_DIED))
-                uval = cmpxchg_futex_value_locked(uaddr, current->pid, 0);
+                uval = cmpxchg_futex_value_locked(uaddr, task_pid_vnr(current), 0);
 
 
         if (unlikely(uval == -EFAULT))
@@ -1617,7 +1621,7 @@ retry_unlocked:
          * Rare case: we managed to release the lock atomically,
          * no need to wake anyone else up:
          */
-        if (unlikely(uval == current->pid))
+        if (unlikely(uval == task_pid_vnr(current)))
                 goto out_unlock;
 
         /*
@@ -1854,7 +1858,8 @@ sys_get_robust_list(int pid, struct robust_list_head __user * __user *head_ptr,
 
                 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;
@@ -1887,7 +1892,7 @@ retry:
         if (get_user(uval, uaddr))
                 return -1;
 
-        if ((uval & FUTEX_TID_MASK) == curr->pid) {
+        if ((uval & FUTEX_TID_MASK) == task_pid_vnr(curr)) {
                 /*
                  * Ok, this dying thread is truly holding a futex
                  * of interest. Set the OWNER_DIED bit atomically