The patch titled
Subject: pidns: expose task pid_ns_for_children to userspace
has been added to the -mm tree. Its filename is
pidns-expose-task-pid_ns_for_children-to-userspace.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/pidns-expose-task-pid_ns_for_children-to-userspace.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/pidns-expose-task-pid_ns_for_children-to-userspace.patch
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------------------------------------------------------
From: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
Subject: pidns: expose task pid_ns_for_children to userspace
pid_ns_for_children set by a task is known only to the task itself, and
it's impossible to identify it from outside.
It's a big problem for checkpoint/restore software like CRIU, because it
can't correctly handle tasks, that do setns(CLONE_NEWPID) in proccess of
their work.
This patch solves the problem, and it exposes pid_ns_for_children to ns
directory in standard way with the name "pid_for_children":
~# ls /proc/5531/ns -l | grep pid
lrwxrwxrwx 1 root root 0 Jan 14 16:38 pid -> pid:[4026531836]
lrwxrwxrwx 1 root root 0 Jan 14 16:38 pid_for_children -> pid:[4026532286]
Link: http://lkml.kernel.org/r/149201123914.6007.2187327078064239572.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
Cc: Andrei Vagin <avagin@xxxxxxxxxxxxx>
Cc: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Paul Moore <paul@xxxxxxxxxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Serge Hallyn <serge@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/namespaces.c | 1 +
include/linux/proc_ns.h | 1 +
kernel/pid_namespace.c | 34 ++++++++++++++++++++++++++++++++++
3 files changed, 36 insertions(+)
diff -puN fs/proc/namespaces.c~pidns-expose-task-pid_ns_for_children-to-userspace fs/proc/namespaces.c
--- a/fs/proc/namespaces.c~pidns-expose-task-pid_ns_for_children-to-userspace
+++ a/fs/proc/namespaces.c
@@ -23,6 +23,7 @@ static const struct proc_ns_operations *
#endif
#ifdef CONFIG_PID_NS
&pidns_operations,
+ &pidns_for_children_operations,
#endif
#ifdef CONFIG_USER_NS
&userns_operations,
diff -puN include/linux/proc_ns.h~pidns-expose-task-pid_ns_for_children-to-userspace include/linux/proc_ns.h
--- a/include/linux/proc_ns.h~pidns-expose-task-pid_ns_for_children-to-userspace
+++ a/include/linux/proc_ns.h
@@ -27,6 +27,7 @@ extern const struct proc_ns_operations n
extern const struct proc_ns_operations utsns_operations;
extern const struct proc_ns_operations ipcns_operations;
extern const struct proc_ns_operations pidns_operations;
+extern const struct proc_ns_operations pidns_for_children_operations;
extern const struct proc_ns_operations userns_operations;
extern const struct proc_ns_operations mntns_operations;
extern const struct proc_ns_operations cgroupns_operations;
diff -puN kernel/pid_namespace.c~pidns-expose-task-pid_ns_for_children-to-userspace kernel/pid_namespace.c
--- a/kernel/pid_namespace.c~pidns-expose-task-pid_ns_for_children-to-userspace
+++ a/kernel/pid_namespace.c
@@ -374,6 +374,29 @@ static struct ns_common *pidns_get(struc
return ns ? &ns->ns : NULL;
}
+static struct ns_common *pidns_for_children_get(struct task_struct *task)
+{
+ struct pid_namespace *ns = NULL;
+
+ task_lock(task);
+ if (task->nsproxy) {
+ ns = task->nsproxy->pid_ns_for_children;
+ get_pid_ns(ns);
+ }
+ task_unlock(task);
+
+ if (ns) {
+ read_lock(&tasklist_lock);
+ if (!ns->child_reaper) {
+ put_pid_ns(ns);
+ ns = NULL;
+ }
+ read_unlock(&tasklist_lock);
+ }
+
+ return ns ? &ns->ns : NULL;
+}
+
static void pidns_put(struct ns_common *ns)
{
put_pid_ns(to_pid_ns(ns));
@@ -440,6 +463,17 @@ const struct proc_ns_operations pidns_op
.put = pidns_put,
.install = pidns_install,
.owner = pidns_owner,
+ .get_parent = pidns_get_parent,
+};
+
+const struct proc_ns_operations pidns_for_children_operations = {
+ .name = "pid_for_children",
+ .real_ns_name = "pid",
+ .type = CLONE_NEWPID,
+ .get = pidns_for_children_get,
+ .put = pidns_put,
+ .install = pidns_install,
+ .owner = pidns_owner,
.get_parent = pidns_get_parent,
};
_
Patches currently in -mm which might be from ktkhai@xxxxxxxxxxxxx are
ns-allow-ns_entries-to-have-custom-symlink-content.patch
pidns-expose-task-pid_ns_for_children-to-userspace.patch
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