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, 19 insertions, 8 deletions

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 24f7f9f..04b689f 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -77,6 +77,7 @@
 #include <linux/cpuset.h>
 #include <linux/rcupdate.h>
 #include <linux/delayacct.h>
+#include <linux/pid_namespace.h>
 
 #include <asm/pgtable.h>
 #include <asm/processor.h>
@@ -161,8 +162,15 @@ static inline char *task_state(struct task_struct *p, char *buffer)
 	struct group_info *group_info;
 	int g;
 	struct fdtable *fdt = NULL;
+	struct pid_namespace *ns;
+	pid_t ppid, tpid;
 
+	ns = current->nsproxy->pid_ns;
 	rcu_read_lock();
+	ppid = pid_alive(p) ?
+		task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
+	tpid = pid_alive(p) && p->ptrace ?
+		task_ppid_nr_ns(rcu_dereference(p->parent), ns) : 0;
 	buffer += sprintf(buffer,
 		"State:\t%s\n"
 		"Tgid:\t%d\n"
@@ -172,9 +180,9 @@ static inline char *task_state(struct task_struct *p, char *buffer)
 		"Uid:\t%d\t%d\t%d\t%d\n"
 		"Gid:\t%d\t%d\t%d\t%d\n",
 		get_task_state(p),
-		p->tgid, p->pid,
-		pid_alive(p) ? rcu_dereference(p->real_parent)->tgid : 0,
-		pid_alive(p) && p->ptrace ? rcu_dereference(p->parent)->pid : 0,
+		task_tgid_nr_ns(p, ns),
+		task_pid_nr_ns(p, ns),
+		ppid, tpid,
 		p->uid, p->euid, p->suid, p->fsuid,
 		p->gid, p->egid, p->sgid, p->fsgid);
 
@@ -394,6 +402,9 @@ static int do_task_stat(struct task_struct *task, char *buffer, int whole)
 	unsigned long rsslim = 0;
 	char tcomm[sizeof(task->comm)];
 	unsigned long flags;
+	struct pid_namespace *ns;
+
+	ns = current->nsproxy->pid_ns;
 
 	state = *get_task_state(task);
 	vsize = eip = esp = 0;
@@ -416,7 +427,7 @@ static int do_task_stat(struct task_struct *task, char *buffer, int whole)
 		struct signal_struct *sig = task->signal;
 
 		if (sig->tty) {
-			tty_pgrp = pid_nr(sig->tty->pgrp);
+			tty_pgrp = pid_nr_ns(sig->tty->pgrp, ns);
 			tty_nr = new_encode_dev(tty_devnum(sig->tty));
 		}
 
@@ -449,9 +460,9 @@ static int do_task_stat(struct task_struct *task, char *buffer, int whole)
 			gtime += cputime_add(gtime, sig->gtime);
 		}
 
-		sid = task_session_nr(task);
-		pgid = task_pgrp_nr(task);
-		ppid = rcu_dereference(task->real_parent)->tgid;
+		sid = task_session_nr_ns(task, ns);
+		pgid = task_pgrp_nr_ns(task, ns);
+		ppid = task_ppid_nr_ns(task, ns);
 
 		unlock_task_sighand(task, &flags);
 	}
@@ -483,7 +494,7 @@ static int do_task_stat(struct task_struct *task, char *buffer, int whole)
 	res = sprintf(buffer, "%d (%s) %c %d %d %d %d %d %u %lu \
 %lu %lu %lu %lu %lu %ld %ld %ld %ld %d 0 %llu %lu %ld %lu %lu %lu %lu %lu \
 %lu %lu %lu %lu %lu %lu %lu %lu %d %d %u %u %llu %lu %ld\n",
-		task->pid,
+		task_pid_nr_ns(task, ns),
 		tcomm,
 		state,
 		ppid,