[PATCH 14/16] Make pid namespaces clonnable

Pavel Emelianov
2007-07-06T08:13:55Z

Just add the support for cloning pid namespaces.

Note that the namespace is destroyed via schedule_work(). This is
done so, since the namespace will put the proc_mnt and thus may
fall asleep.

Signed-off-by: Pavel Emelianov <xemul@openvz.org>

---

include/linux/pid_namespace.h | 5 +-
include/linux/sched.h | 1
kernel/fork.c | 26 ++++++++---
kernel/nsproxy.c | 2
kernel/pid.c | 96 ++++++++++++++++++++++++++++++++++++++++--
5 files changed, 118 insertions(+), 12 deletions(-)

--- ./include/linux/pid_namespace.h.ve13 2007-07-06 11:05:05.000000000 +0400
+++ ./include/linux/pid_namespace.h 2007-07-06 11:05:05.000000000 +0400
@@ -15,7 +15,10 @@ struct pidmap {
#define PIDMAP_ENTRIES ((PID_MAX_LIMIT + 8*PAGE_SIZE - 1)/PAGE_SIZE/8)

struct pid_namespace {
- struct kref kref;
+ union {
+ struct kref kref;
+ struct work_struct free_work;
+ };
struct pidmap pidmap[PIDMAP_ENTRIES];
int last_pid;
int level;
--- ./include/linux/sched.h.ve13 2007-07-06 11:05:05.000000000 +0400
+++ ./include/linux/sched.h 2007-07-06 11:05:23.000000000 +0400
@@ -26,6 +26,7 @@
#define CLONE_NEWUTS 0x04000000 /* New utsname group? */
#define CLONE_NEWIPC 0x08000000 /* New ipcs */
#define CLONE_NEWUSER 0x10000000 /* New user namespace */
+#define CLONE_NEWPIDS 0x20000000 /* New pids */

/*
* Scheduling policies
--- ./kernel/fork.c.ve13 2007-07-06 11:05:05.000000000 +0400
+++ ./kernel/fork.c 2007-07-06 11:05:05.000000000 +0400
@@ -1267,11 +1267,22 @@ static struct task_struct *copy_process(
__ptrace_link(p, current->parent);

if (thread_group_leader(p)) {
- p->signal->tty = current->signal->tty;
- p->signal->pgrp = task_pgrp_nr(current);
- set_task_session(p, task_session_nr(current));
- attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
- attach_pid(p, PIDTYPE_SID, task_session(current));
+ if (clone_flags & CLONE_NEWPIDS) {
+ p->nsproxy->pid_ns->child_reaper = p;
+ p->signal->tty = NULL;
+ p->signal->pgrp = p->pid;
+ set_task_session(p, p->pid);
+ attach_pid(p, PIDTYPE_PGID, pid);
+ attach_pid(p, PIDTYPE_SID, pid);
+ } else {
+ p->signal->tty = current->signal->tty;
+ p->signal->pgrp = task_pgrp_nr(current);
+ set_task_session(p, task_session_nr(current));
+ attach_pid(p, PIDTYPE_PGID,
+ task_pgrp(current));
+ attach_pid(p, PIDTYPE_SID,
+ task_session(current));
+ }

list_add_tail_rcu(&p->tasks, &init_task.tasks);
__get_cpu_var(process_counts)++;
@@ -1423,7 +1434,10 @@ long do_fork(unsigned long clone_flags,
else
p->state = TASK_STOPPED;

- nr = pid_vnr(task_pid(p));
+ nr = (clone_flags & CLONE_NEWPIDS) ?
+ pid_nr_ns(task_pid(p), current->nsproxy->pid_ns) :
+ pid_vnr(task_pid(p));
+
if (unlikely (trace)) {
current->ptrace_message = nr;
ptrace_notify ((trace << 8) | SIGTRAP);
--- ./kernel/nsproxy.c.ve13 2007-07-06 10:58:57.000000000 +0400
+++ ./kernel/nsproxy.c 2007-07-06 11:05:39.000000000 +0400
@@ -184,7 +184,7 @@ int unshare_nsproxy_namespaces(unsigned
int err = 0;

if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
- CLONE_NEWUSER)))
+ CLONE_NEWUSER | CLONE_NEWPIDS)))
return 0;

if (!capable(CAP_SYS_ADMIN))
--- ./kernel/pid.c.ve13 2007-07-06 11:05:05.000000000 +0400
+++ ./kernel/pid.c 2007-07-06 11:06:47.000000000 +0400
@@ -62,8 +62,10 @@ static inline int mk_pid(struct pid_name
* the scheme scales to up to 4 million PIDs, runtime.
*/
struct pid_namespace init_pid_ns = {
- .kref = {
- .refcount = ATOMIC_INIT(2),
+ {
+ .kref = {
+ .refcount = ATOMIC_INIT(2),
+ },
},
.pidmap = {
[ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL }
@@ -457,11 +459,96 @@ out:
return cachep;
}

+static struct pid_namespace *create_pid_namespace(int level)
+{
+ struct pid_namespace *ns;
+ int i;
+
+ ns = kmalloc(sizeof(struct pid_namespace), GFP_KERNEL);
+ if (ns == NULL)
+ goto out;
+
+ ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!ns->pidmap[0].page)
+ goto out_free;
+
+ ns->pid_cachep = create_pid_cachep(level);
+ if (ns->pid_cachep == NULL)
+ goto out_free_map;
+
+ kref_init(&ns->kref);
+ ns->last_pid = 0;
+ ns->child_reaper = NULL;
+ ns->level = level;
+
+ if (pid_ns_prepare_proc(ns))
+ goto out_free_cachep;
+
+ set_bit(0, ns->pidmap[0].page);
+ atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
+ get_pid_ns(ns);
+
+ for (i = 1; i < PIDMAP_ENTRIES; i++) {
+ ns->pidmap[i].page = 0;
+ atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
+ }
+
+ return ns;
+
+out_free_cachep:
+out_free_map:
+ kfree(ns->pidmap[0].page);
+out_free:
+ kfree(ns);
+out:
+ return ERR_PTR(-ENOMEM);
+}
+
+static void destroy_pid_namespace(struct pid_namespace *ns)
+{
+ int i;
+
+ synchronize_rcu();
+ pid_ns_release_proc(ns);
+ atomic_inc(&ns->pidmap[0].nr_free);
+ for (i = 0; i < PIDMAP_ENTRIES; i++)
+ kfree(ns->pidmap[i].page);
+ kfree(ns);
+}
+
struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old_ns)
{
+ struct pid_namespace *new_ns;
+
BUG_ON(!old_ns);
get_pid_ns(old_ns);
- return old_ns;
+ new_ns = old_ns;
+ if (!(flags & CLONE_NEWPIDS))
+ goto out;
+
+ new_ns = ERR_PTR(-EINVAL);
+ if (flags & CLONE_THREAD)
+ goto out_put;
+
+ new_ns = create_pid_namespace(old_ns->level + 1);
+ if (new_ns != NULL)
+ new_ns->parent = get_pid_ns(old_ns);
+out_put:
+ put_pid_ns(old_ns);
+out:
+ return new_ns;
+}
+
+static void do_free_pid_ns(struct work_struct *w)
+{
+ struct pid_namespace *ns, *parent;
+
+ ns = container_of(w, struct pid_namespace, free_work);
+ parent = ns->parent;
+ destroy_pid_namespace(ns);
+
+ if (parent != NULL)
+ put_pid_ns(parent);
}

void free_pid_ns(struct kref *kref)
@@ -469,7 +556,8 @@ void free_pid_ns(struct kref *kref)
struct pid_namespace *ns;

ns = container_of(kref, struct pid_namespace, kref);
- kfree(ns);
+ INIT_WORK(&ns->free_work, do_free_pid_ns);
+ schedule_work(&ns->free_work);
}

/*