| Message ID | 149086967937.4388.471494976517194744.stgit@localhost.localdomain (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, 30 Mar 2017 13:27:59 +0300 Kirill Tkhai <ktkhai@virtuozzo.com> wrote: > 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] > > --- 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 This interface should be documented somewhere under Documentation/. But I can't immediately find where the /proc/pid/ns/ pseudo-files are documented...
On Thu, Mar 30, 2017 at 03:05:20PM -0700, Andrew Morton wrote: > On Thu, 30 Mar 2017 13:27:59 +0300 Kirill Tkhai <ktkhai@virtuozzo.com> wrote: > > > 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] > > > > --- 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 > > This interface should be documented somewhere under Documentation/. > But I can't immediately find where the /proc/pid/ns/ pseudo-files are > documented... I know that they are documented in man7/namespaces.7 https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/man7/namespaces.7#n187 > >
diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c index 766f0c637ad1..3803b24ca220 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 88dba3b53375..58ab28d81fc2 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; extern const struct proc_ns_operations cgroupns_operations; diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index de461aa0bf9a..4dd02ff0b0bd 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -374,6 +374,20 @@ 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_for_children; + get_pid_ns(ns); + } + task_unlock(task); + + return ns ? &ns->ns : NULL; +} + static void pidns_put(struct ns_common *ns) { put_pid_ns(to_pid_ns(ns)); @@ -443,6 +457,17 @@ 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);