zap_pid_ns_processes() uses force_sig(SIGKILL) to ensure SIGKILL will be
delivered to sub-namespace inits as well.  This is correct, but we are
going to change force_sig_info() semantics.  See
http://bugzilla.kernel.org/show_bug.cgi?id=15395#c31

We can use send_sig_info(SEND_SIG_NOINFO) instead, since
614c517d ("signals: SEND_SIG_NOINFO should
be considered as SI_FROMUSER()") SEND_SIG_NOINFO means "from user" and
therefore send_signal() will get the correct from_ancestor_ns = T flag.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Acked-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

CLONE_PARENT was used to implement an older threading model.  For
consistency with the CLONE_THREAD check in copy_pid_ns(), disable
CLONE_PARENT with CLONE_NEWPID, at least until the required semantics of
pid namespaces are clear.
Signed-off-by: NSukadev Bhattiprolu <sukadev@us.ibm.com>
Acked-by: NRoland McGrath <roland@redhat.com>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Cc: Oren Laadan <orenl@cs.columbia.edu>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

copy_pid_ns() is a perfect example of a case where unwinding leads to more
code and makes it less clear.  Watch the diffstat.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Reviewed-by: NSerge Hallyn <serue@us.ibm.com>
Acked-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Reviewed-by: NWANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

create_pid_namespace() creates everything, but caller has to assign parent
pidns by hand, which is unnatural.  At the moment of call new ->level has
to be taken from somewhere and parent pidns is already available.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Acked-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Reviewed-by: NWANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

send_signal() assumes that signals with SEND_SIG_PRIV are generated from
within the same namespace.  So any nested container-init processes become
immune to the SIGKILL generated by kill_proc_info() in
zap_pid_ns_processes().

Use force_sig() in zap_pid_ns_processes() instead - force_sig() clears the
SIGNAL_UNKILLABLE flag ensuring the signal is processed by
container-inits.
Signed-off-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We don't change pid_ns->child_reaper when the main thread of the
subnamespace init exits.  As Robert Rex <robert.rex@exasol.com> pointed
out this is wrong.

Yes, the re-parenting itself works correctly, but if the reparented task
exits it needs ->parent->nsproxy->pid_ns in do_notify_parent(), and if the
main thread is zombie its ->nsproxy was already cleared by
exit_task_namespaces().

Introduce the new function, find_new_reaper(), which finds the new
->parent for the re-parenting and changes ->child_reaper if needed.  Kill
the now unneeded exit_child_reaper().

Also move the changing of ->child_reaper from zap_pid_ns_processes() to
find_new_reaper(), this consolidates the games with ->child_reaper and
makes it stable under tasklist_lock.

Addresses http://bugzilla.kernel.org/show_bug.cgi?id=11391Reported-by: NRobert Rex <robert.rex@exasol.com>
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Acked-by: NPavel Emelyanov <xemul@openvz.org>
Acked-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

zap_pid_ns_processes() sets pid_ns->child_reaper = NULL, this is wrong.

Yes, we have already killed all tasks in this namespace, and sys_wait4()
doesn't see any child.  But this doesn't mean ->children list is empty, we
may have EXIT_DEAD tasks which are not visible to do_wait().  In that case
the subsequent forget_original_parent() will crash the kernel because it
will try to re-parent these tasks to the NULL reaper.

Even if there are no childs, it is not good that forget_original_parent()
uses reaper == NULL.

Change the code to set ->child_reaper = init_pid_ns.child_reaper instead.
We could use pid_ns->parent->child_reaper as well, I think this does not
really matter.  These EXIT_DEAD tasks are not visible to the new ->parent
after re-parenting, they will silently do release_task() eventually.

Note that we must change ->child_reaper, otherwise
forget_original_parent() will use reaper == father, and in that case we
will hit the (correct) BUG_ON(!list_empty(&father->children)).
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Acked-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Acked-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Allocate the structure on the first call to sys_acct().  After this each
namespace, that ordered the accounting, will live with this structure till
its own death.

Two notes
- routines, that close the accounting on fs umount time use
  the init_pid_ns's acct by now;
- accounting routine accounts to dying task's namespace
  (also by now).
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It makes many fields initialization implicit helping in auto-setting
#ifdef-ed fields (bsd-acct related pointer will be such).
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

These values represent the nesting level of a namespace and pids living in it,
and it's always non-negative.

Turning this from int to unsigned int saves some space in pid.c (11 bytes on
x86 and 64 on ia64) by letting the compiler optimize the pid_nr_ns a bit.
E.g.  on ia64 this removes the sign extension calls, which compiler adds to
optimize access to pid->nubers[ns->level].
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kernel/cpuset.c:1268:52: warning: Using plain integer as NULL pointer
kernel/pid_namespace.c:95:24: warning: Using plain integer as NULL pointer
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Reviewed-by: NPaul Jackson <pj@sgi.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Just like with the user namespaces, move the namespace management code into
the separate .c file and mark the (already existing) PID_NS option as "depend
on NAMESPACES"

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>