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, 33 insertions, 21 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index 4cfa213a5ac2..23620d52cf37 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -152,7 +152,8 @@ asmlinkage long sys_setpriority(int which, int who, int niceval)
         switch (which) {
                 case PRIO_PROCESS:
                         if (who)
-                                p = find_task_by_pid(who);
+                                p = find_task_by_pid_ns(who,
+                                                current->nsproxy->pid_ns);
                         else
                                 p = current;
                         if (p)
@@ -160,7 +161,7 @@ asmlinkage long sys_setpriority(int which, int who, int niceval)
                         break;
                 case PRIO_PGRP:
                         if (who)
-                                pgrp = find_pid(who);
+                                pgrp = find_vpid(who);
                         else
                                 pgrp = task_pgrp(current);
                         do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
@@ -209,7 +210,8 @@ asmlinkage long sys_getpriority(int which, int who)
         switch (which) {
                 case PRIO_PROCESS:
                         if (who)
-                                p = find_task_by_pid(who);
+                                p = find_task_by_pid_ns(who,
+                                                current->nsproxy->pid_ns);
                         else
                                 p = current;
                         if (p) {
@@ -220,7 +222,7 @@ asmlinkage long sys_getpriority(int which, int who)
                         break;
                 case PRIO_PGRP:
                         if (who)
-                                pgrp = find_pid(who);
+                                pgrp = find_vpid(who);
                         else
                                 pgrp = task_pgrp(current);
                         do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
@@ -917,9 +919,10 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
         struct task_struct *p;
         struct task_struct *group_leader = current->group_leader;
         int err = -EINVAL;
+        struct pid_namespace *ns;
 
         if (!pid)
-                pid = group_leader->pid;
+                pid = task_pid_vnr(group_leader);
         if (!pgid)
                 pgid = pid;
         if (pgid < 0)
@@ -928,10 +931,12 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
         /* From this point forward we keep holding onto the tasklist lock
          * so that our parent does not change from under us. -DaveM
          */
+        ns = current->nsproxy->pid_ns;
+
         write_lock_irq(&tasklist_lock);
 
         err = -ESRCH;
-        p = find_task_by_pid(pid);
+        p = find_task_by_pid_ns(pid, ns);
         if (!p)
                 goto out;
 
@@ -957,9 +962,9 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
                 goto out;
 
         if (pgid != pid) {
-                struct task_struct *g =
-                        find_task_by_pid_type(PIDTYPE_PGID, pgid);
+                struct task_struct *g;
 
+                g = find_task_by_pid_type_ns(PIDTYPE_PGID, pgid, ns);
                 if (!g || task_session(g) != task_session(group_leader))
                         goto out;
         }
@@ -968,10 +973,13 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
         if (err)
                 goto out;
 
-        if (task_pgrp_nr(p) != pgid) {
+        if (task_pgrp_nr_ns(p, ns) != pgid) {
+                struct pid *pid;
+
                 detach_pid(p, PIDTYPE_PGID);
-                p->signal->pgrp = pgid;
-                attach_pid(p, PIDTYPE_PGID, find_pid(pgid));
+                pid = find_vpid(pgid);
+                attach_pid(p, PIDTYPE_PGID, pid);
+                p->signal->pgrp = pid_nr(pid);
         }
 
         err = 0;
@@ -984,19 +992,21 @@ out:
 asmlinkage long sys_getpgid(pid_t pid)
 {
         if (!pid)
-                return task_pgrp_nr(current);
+                return task_pgrp_vnr(current);
         else {
                 int retval;
                 struct task_struct *p;
+                struct pid_namespace *ns;
 
-                read_lock(&tasklist_lock);
-                p = find_task_by_pid(pid);
+                ns = current->nsproxy->pid_ns;
 
+                read_lock(&tasklist_lock);
+                p = find_task_by_pid_ns(pid, ns);
                 retval = -ESRCH;
                 if (p) {
                         retval = security_task_getpgid(p);
                         if (!retval)
-                                retval = task_pgrp_nr(p);
+                                retval = task_pgrp_nr_ns(p, ns);
                 }
                 read_unlock(&tasklist_lock);
                 return retval;
@@ -1008,7 +1018,7 @@ asmlinkage long sys_getpgid(pid_t pid)
 asmlinkage long sys_getpgrp(void)
 {
         /* SMP - assuming writes are word atomic this is fine */
-        return task_pgrp_nr(current);
+        return task_pgrp_vnr(current);
 }
 
 #endif
@@ -1016,19 +1026,21 @@ asmlinkage long sys_getpgrp(void)
 asmlinkage long sys_getsid(pid_t pid)
 {
         if (!pid)
-                return task_session_nr(current);
+                return task_session_vnr(current);
         else {
                 int retval;
                 struct task_struct *p;
+                struct pid_namespace *ns;
 
-                read_lock(&tasklist_lock);
-                p = find_task_by_pid(pid);
+                ns = current->nsproxy->pid_ns;
 
+                read_lock(&tasklist_lock);
+                p = find_task_by_pid_ns(pid, ns);
                 retval = -ESRCH;
                 if (p) {
                         retval = security_task_getsid(p);
                         if (!retval)
-                                retval = task_session_nr(p);
+                                retval = task_session_nr_ns(p, ns);
                 }
                 read_unlock(&tasklist_lock);
                 return retval;
@@ -1065,7 +1077,7 @@ asmlinkage long sys_setsid(void)
         group_leader->signal->tty = NULL;
         spin_unlock(&group_leader->sighand->siglock);
 
-        err = task_pgrp_nr(group_leader);
+        err = task_pgrp_vnr(group_leader);
 out:
         write_unlock_irq(&tasklist_lock);
         return err;