From: Kirill Tkhai <[email protected]> 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 <[email protected]> Cc: Andrei Vagin <[email protected]> Cc: Andreas Gruenbacher <[email protected]> Cc: Kees Cook <[email protected]> Cc: Michael Kerrisk <[email protected]> Cc: Al Viro <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Paul Moore <[email protected]> Cc: Eric Biederman <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Serge Hallyn <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> (cherry picked from VZ8 commit eaa0d190bfe1ed891b814a52712dcd852554cb08) https://jira.sw.ru/browse/PSBM-102357 Signed-off-by: Pavel Tikhomirov <[email protected]> --- fs/proc/namespaces.c | 1 + include/linux/proc_ns.h | 1 + kernel/pid_namespace.c | 34 ++++++++++++++++++++++++++++++++++ 3 files changed, 36 insertions(+) diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c index 49d459f05546..c9bb30b97401 100644 --- a/fs/proc/namespaces.c +++ b/fs/proc/namespaces.c @@ -23,6 +23,7 @@ static const struct proc_ns_operations *ns_entries[] = { #endif #ifdef CONFIG_PID_NS &pidns_operations, + &pidns_for_children_operations, #endif #ifdef CONFIG_USER_NS &userns_operations, diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h index ea002b8e5ab9..dc925ebb4ed2 100644 --- a/include/linux/proc_ns.h +++ b/include/linux/proc_ns.h @@ -27,6 +27,7 @@ extern const struct proc_ns_operations netns_operations; 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; diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index c5541caf7a09..df3361aaa3a6 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -361,6 +361,29 @@ static struct ns_common *pidns_get(struct task_struct *task) 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; + get_pid_ns(ns); + } + task_unlock(task); + + if (ns) { + qread_lock(&tasklist_lock); + if (!ns->child_reaper) { + put_pid_ns(ns); + ns = NULL; + } + qread_unlock(&tasklist_lock); + } + + return ns ? &ns->ns : NULL; +} + static void pidns_put(struct ns_common *ns) { put_pid_ns(to_pid_ns(ns)); @@ -430,6 +453,17 @@ const struct proc_ns_operations pidns_operations = { .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, +}; + static __init int pid_namespaces_init(void) { pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC); -- 2.24.1 _______________________________________________ Devel mailing list [email protected] https://lists.openvz.org/mailman/listinfo/devel
