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, 23 insertions, 14 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 21510c9aa89c..db7636041c10 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1937,14 +1937,14 @@ static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
 			      int buflen)
 {
 	char tmp[PROC_NUMBUF];
-	sprintf(tmp, "%d", current->tgid);
+	sprintf(tmp, "%d", task_tgid_vnr(current));
 	return vfs_readlink(dentry,buffer,buflen,tmp);
 }
 
 static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
 {
 	char tmp[PROC_NUMBUF];
-	sprintf(tmp, "%d", current->tgid);
+	sprintf(tmp, "%d", task_tgid_vnr(current));
 	return ERR_PTR(vfs_follow_link(nd,tmp));
 }
 
@@ -2316,6 +2316,7 @@ struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, struct
 	struct dentry *result = ERR_PTR(-ENOENT);
 	struct task_struct *task;
 	unsigned tgid;
+	struct pid_namespace *ns;
 
 	result = proc_base_lookup(dir, dentry);
 	if (!IS_ERR(result) || PTR_ERR(result) != -ENOENT)
@@ -2325,8 +2326,9 @@ struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, struct
 	if (tgid == ~0U)
 		goto out;
 
+	ns = dentry->d_sb->s_fs_info;
 	rcu_read_lock();
-	task = find_task_by_pid(tgid);
+	task = find_task_by_pid_ns(tgid, ns);
 	if (task)
 		get_task_struct(task);
 	rcu_read_unlock();
@@ -2343,7 +2345,8 @@ out:
  * Find the first task with tgid >= tgid
  *
  */
-static struct task_struct *next_tgid(unsigned int tgid)
+static struct task_struct *next_tgid(unsigned int tgid,
+		struct pid_namespace *ns)
 {
 	struct task_struct *task;
 	struct pid *pid;
@@ -2351,9 +2354,9 @@ static struct task_struct *next_tgid(unsigned int tgid)
 	rcu_read_lock();
 retry:
 	task = NULL;
-	pid = find_ge_pid(tgid, &init_pid_ns);
+	pid = find_ge_pid(tgid, ns);
 	if (pid) {
-		tgid = pid->nr + 1;
+		tgid = pid_nr_ns(pid, ns) + 1;
 		task = pid_task(pid, PIDTYPE_PID);
 		/* What we to know is if the pid we have find is the
 		 * pid of a thread_group_leader.  Testing for task
@@ -2393,6 +2396,7 @@ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
 	struct task_struct *reaper = get_proc_task(filp->f_path.dentry->d_inode);
 	struct task_struct *task;
 	int tgid;
+	struct pid_namespace *ns;
 
 	if (!reaper)
 		goto out_no_task;
@@ -2403,11 +2407,12 @@ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
 			goto out;
 	}
 
+	ns = filp->f_dentry->d_sb->s_fs_info;
 	tgid = filp->f_pos - TGID_OFFSET;
-	for (task = next_tgid(tgid);
+	for (task = next_tgid(tgid, ns);
 	     task;
-	     put_task_struct(task), task = next_tgid(tgid + 1)) {
-		tgid = task->pid;
+	     put_task_struct(task), task = next_tgid(tgid + 1, ns)) {
+		tgid = task_pid_nr_ns(task, ns);
 		filp->f_pos = tgid + TGID_OFFSET;
 		if (proc_pid_fill_cache(filp, dirent, filldir, task, tgid) < 0) {
 			put_task_struct(task);
@@ -2531,6 +2536,7 @@ static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry
 	struct task_struct *task;
 	struct task_struct *leader = get_proc_task(dir);
 	unsigned tid;
+	struct pid_namespace *ns;
 
 	if (!leader)
 		goto out_no_task;
@@ -2539,8 +2545,9 @@ static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry
 	if (tid == ~0U)
 		goto out;
 
+	ns = dentry->d_sb->s_fs_info;
 	rcu_read_lock();
-	task = find_task_by_pid(tid);
+	task = find_task_by_pid_ns(tid, ns);
 	if (task)
 		get_task_struct(task);
 	rcu_read_unlock();
@@ -2571,14 +2578,14 @@ out_no_task:
  * threads past it.
  */
 static struct task_struct *first_tid(struct task_struct *leader,
-					int tid, int nr)
+		int tid, int nr, struct pid_namespace *ns)
 {
 	struct task_struct *pos;
 
 	rcu_read_lock();
 	/* Attempt to start with the pid of a thread */
 	if (tid && (nr > 0)) {
-		pos = find_task_by_pid(tid);
+		pos = find_task_by_pid_ns(tid, ns);
 		if (pos && (pos->group_leader == leader))
 			goto found;
 	}
@@ -2647,6 +2654,7 @@ static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldi
 	ino_t ino;
 	int tid;
 	unsigned long pos = filp->f_pos;  /* avoiding "long long" filp->f_pos */
+	struct pid_namespace *ns;
 
 	task = get_proc_task(inode);
 	if (!task)
@@ -2680,12 +2688,13 @@ static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldi
 	/* f_version caches the tgid value that the last readdir call couldn't
 	 * return. lseek aka telldir automagically resets f_version to 0.
 	 */
+	ns = filp->f_dentry->d_sb->s_fs_info;
 	tid = (int)filp->f_version;
 	filp->f_version = 0;
-	for (task = first_tid(leader, tid, pos - 2);
+	for (task = first_tid(leader, tid, pos - 2, ns);
 	     task;
 	     task = next_tid(task), pos++) {
-		tid = task->pid;
+		tid = task_pid_nr_ns(task, ns);
 		if (proc_task_fill_cache(filp, dirent, filldir, task, tid) < 0) {
 			/* returning this tgid failed, save it as the first
 			 * pid for the next readir call */