pid: Extend/Fix pid_vnr

pid_vnr returns the user space pid with respect to the pid namespace the
struct pid was allocated in.  What we want before we return a pid to user
space is the user space pid with respect to the pid namespace of current.

pid_vnr is a very nice optimization but because it isn't quite what we want
it is easy to use pid_vnr at times when we aren't certain the struct pid
was allocated in our pid namespace.

Currently this describes at least tiocgpgrp and tiocgsid in ttyio.c the
parent process reported in the core dumps and the parent process in
get_signal_to_deliver.

So unless the performance impact is huge having an interface that does what
we want instead of always what we want should be much more reliable and
much less error prone.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/pid.h b/include/linux/pid.h
index 061abb6c0796bb2b648ecb0a79843c7a7da2e6d7..b91f4732dc1b7f4b883e155ed1c4e7defbce8502 100644 (file)
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -127,9 +127,8 @@ extern void FASTCALL(free_pid(struct pid *pid));
  * the helpers to get the pid's id seen from different namespaces
  *
  * pid_nr()    : global id, i.e. the id seen from the init namespace;
- * pid_vnr()   : virtual id, i.e. the id seen from the namespace this pid
- *               belongs to. this only makes sence when called in the
- *               context of the task that belongs to the same namespace;
+ * pid_vnr()   : virtual id, i.e. the id seen from the pid namespace of
+ *               current.
  * pid_nr_ns() : id seen from the ns specified.
  *
  * see also task_xid_nr() etc in include/linux/sched.h
@@ -144,14 +143,7 @@ static inline pid_t pid_nr(struct pid *pid)
 }
 
 pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns);
-
-static inline pid_t pid_vnr(struct pid *pid)
-{
-       pid_t nr = 0;
-       if (pid)
-               nr = pid->numbers[pid->level].nr;
-       return nr;
-}
+pid_t pid_vnr(struct pid *pid);
 
 #define do_each_pid_task(pid, type, task)                              \
        do {                                                            \

diff --git a/include/linux/sched.h b/include/linux/sched.h
index d1c9b7f1d51ebe54690b8d85615bcc7444cd0196..3deb6e5d3096aef88ad801e0800e30b8fe0a6f53 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1332,9 +1332,8 @@ struct pid_namespace;
  * from various namespaces
  *
  * task_xid_nr()     : global id, i.e. the id seen from the init namespace;
- * task_xid_vnr()    : virtual id, i.e. the id seen from the namespace the task
- *                     belongs to. this only makes sence when called in the
- *                     context of the task that belongs to the same namespace;
+ * task_xid_vnr()    : virtual id, i.e. the id seen from the pid namespace of
+ *                     current.
  * task_xid_nr_ns()  : id seen from the ns specified;
  *
  * set_task_vxid()   : assigns a virtual id to a task;

diff --git a/kernel/pid.c b/kernel/pid.c
index 939746fb4ce770f0a5ea5fa828dfbf11da69d96a..a32859c4a3cd725cebb02f43e11e04a6cdef6888 100644 (file)
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -443,6 +443,12 @@ pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
        return nr;
 }
 
+pid_t pid_vnr(struct pid *pid)
+{
+       return pid_nr_ns(pid, current->nsproxy->pid_ns);
+}
+EXPORT_SYMBOL_GPL(pid_vnr);
+
 pid_t task_pid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
 {
        return pid_nr_ns(task_pid(tsk), ns);