296 lines
6.8 KiB
C
296 lines
6.8 KiB
C
/*
|
|
* Pid namespaces
|
|
*
|
|
* Authors:
|
|
* (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc.
|
|
* (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM
|
|
* Many thanks to Oleg Nesterov for comments and help
|
|
*
|
|
*/
|
|
|
|
#include <linux/pid.h>
|
|
#include <linux/pid_namespace.h>
|
|
#include <linux/syscalls.h>
|
|
#include <linux/err.h>
|
|
#include <linux/acct.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/proc_fs.h>
|
|
#include <linux/reboot.h>
|
|
#include <linux/export.h>
|
|
|
|
#define BITS_PER_PAGE (PAGE_SIZE*8)
|
|
|
|
struct pid_cache {
|
|
int nr_ids;
|
|
char name[16];
|
|
struct kmem_cache *cachep;
|
|
struct list_head list;
|
|
};
|
|
|
|
static LIST_HEAD(pid_caches_lh);
|
|
static DEFINE_MUTEX(pid_caches_mutex);
|
|
static struct kmem_cache *pid_ns_cachep;
|
|
|
|
/*
|
|
* creates the kmem cache to allocate pids from.
|
|
* @nr_ids: the number of numerical ids this pid will have to carry
|
|
*/
|
|
|
|
static struct kmem_cache *create_pid_cachep(int nr_ids)
|
|
{
|
|
struct pid_cache *pcache;
|
|
struct kmem_cache *cachep;
|
|
|
|
mutex_lock(&pid_caches_mutex);
|
|
list_for_each_entry(pcache, &pid_caches_lh, list)
|
|
if (pcache->nr_ids == nr_ids)
|
|
goto out;
|
|
|
|
pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL);
|
|
if (pcache == NULL)
|
|
goto err_alloc;
|
|
|
|
snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids);
|
|
cachep = kmem_cache_create(pcache->name,
|
|
sizeof(struct pid) + (nr_ids - 1) * sizeof(struct upid),
|
|
0, SLAB_HWCACHE_ALIGN, NULL);
|
|
if (cachep == NULL)
|
|
goto err_cachep;
|
|
|
|
pcache->nr_ids = nr_ids;
|
|
pcache->cachep = cachep;
|
|
list_add(&pcache->list, &pid_caches_lh);
|
|
out:
|
|
mutex_unlock(&pid_caches_mutex);
|
|
return pcache->cachep;
|
|
|
|
err_cachep:
|
|
kfree(pcache);
|
|
err_alloc:
|
|
mutex_unlock(&pid_caches_mutex);
|
|
return NULL;
|
|
}
|
|
|
|
static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_pid_ns)
|
|
{
|
|
struct pid_namespace *ns;
|
|
unsigned int level = parent_pid_ns->level + 1;
|
|
int i, err = -ENOMEM;
|
|
|
|
ns = kmem_cache_zalloc(pid_ns_cachep, 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 + 1);
|
|
if (ns->pid_cachep == NULL)
|
|
goto out_free_map;
|
|
|
|
kref_init(&ns->kref);
|
|
ns->level = level;
|
|
ns->parent = get_pid_ns(parent_pid_ns);
|
|
|
|
set_bit(0, ns->pidmap[0].page);
|
|
atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
|
|
|
|
for (i = 1; i < PIDMAP_ENTRIES; i++)
|
|
atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
|
|
|
|
err = pid_ns_prepare_proc(ns);
|
|
if (err)
|
|
goto out_put_parent_pid_ns;
|
|
|
|
return ns;
|
|
|
|
out_put_parent_pid_ns:
|
|
put_pid_ns(parent_pid_ns);
|
|
out_free_map:
|
|
kfree(ns->pidmap[0].page);
|
|
out_free:
|
|
kmem_cache_free(pid_ns_cachep, ns);
|
|
out:
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
static void destroy_pid_namespace(struct pid_namespace *ns)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < PIDMAP_ENTRIES; i++)
|
|
kfree(ns->pidmap[i].page);
|
|
kmem_cache_free(pid_ns_cachep, ns);
|
|
}
|
|
|
|
struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old_ns)
|
|
{
|
|
if (!(flags & CLONE_NEWPID))
|
|
return get_pid_ns(old_ns);
|
|
if (flags & (CLONE_THREAD|CLONE_PARENT))
|
|
return ERR_PTR(-EINVAL);
|
|
return create_pid_namespace(old_ns);
|
|
}
|
|
|
|
void free_pid_ns(struct kref *kref)
|
|
{
|
|
struct pid_namespace *ns, *parent;
|
|
|
|
ns = container_of(kref, struct pid_namespace, kref);
|
|
|
|
parent = ns->parent;
|
|
destroy_pid_namespace(ns);
|
|
|
|
if (parent != NULL)
|
|
put_pid_ns(parent);
|
|
}
|
|
EXPORT_SYMBOL_GPL(free_pid_ns);
|
|
|
|
void zap_pid_ns_processes(struct pid_namespace *pid_ns)
|
|
{
|
|
int nr;
|
|
int rc;
|
|
struct task_struct *task, *me = current;
|
|
|
|
/* Ignore SIGCHLD causing any terminated children to autoreap */
|
|
spin_lock_irq(&me->sighand->siglock);
|
|
me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
|
|
spin_unlock_irq(&me->sighand->siglock);
|
|
|
|
/*
|
|
* The last thread in the cgroup-init thread group is terminating.
|
|
* Find remaining pid_ts in the namespace, signal and wait for them
|
|
* to exit.
|
|
*
|
|
* Note: This signals each threads in the namespace - even those that
|
|
* belong to the same thread group, To avoid this, we would have
|
|
* to walk the entire tasklist looking a processes in this
|
|
* namespace, but that could be unnecessarily expensive if the
|
|
* pid namespace has just a few processes. Or we need to
|
|
* maintain a tasklist for each pid namespace.
|
|
*
|
|
*/
|
|
read_lock(&tasklist_lock);
|
|
nr = next_pidmap(pid_ns, 1);
|
|
while (nr > 0) {
|
|
rcu_read_lock();
|
|
|
|
task = pid_task(find_vpid(nr), PIDTYPE_PID);
|
|
if (task && !__fatal_signal_pending(task))
|
|
send_sig_info(SIGKILL, SEND_SIG_FORCED, task);
|
|
|
|
rcu_read_unlock();
|
|
|
|
nr = next_pidmap(pid_ns, nr);
|
|
}
|
|
read_unlock(&tasklist_lock);
|
|
|
|
/* Firstly reap the EXIT_ZOMBIE children we may have. */
|
|
do {
|
|
clear_thread_flag(TIF_SIGPENDING);
|
|
rc = sys_wait4(-1, NULL, __WALL, NULL);
|
|
} while (rc != -ECHILD);
|
|
|
|
/*
|
|
* sys_wait4() above can't reap the TASK_DEAD children.
|
|
* Make sure they all go away, see __unhash_process().
|
|
*/
|
|
for (;;) {
|
|
bool need_wait = false;
|
|
|
|
read_lock(&tasklist_lock);
|
|
if (!list_empty(¤t->children)) {
|
|
__set_current_state(TASK_UNINTERRUPTIBLE);
|
|
need_wait = true;
|
|
}
|
|
read_unlock(&tasklist_lock);
|
|
|
|
if (!need_wait)
|
|
break;
|
|
schedule();
|
|
}
|
|
|
|
if (pid_ns->reboot)
|
|
current->signal->group_exit_code = pid_ns->reboot;
|
|
|
|
acct_exit_ns(pid_ns);
|
|
return;
|
|
}
|
|
|
|
#ifdef CONFIG_CHECKPOINT_RESTORE
|
|
static int pid_ns_ctl_handler(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
struct ctl_table tmp = *table;
|
|
|
|
if (write && !capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
/*
|
|
* Writing directly to ns' last_pid field is OK, since this field
|
|
* is volatile in a living namespace anyway and a code writing to
|
|
* it should synchronize its usage with external means.
|
|
*/
|
|
|
|
tmp.data = ¤t->nsproxy->pid_ns->last_pid;
|
|
return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
|
|
}
|
|
|
|
extern int pid_max;
|
|
static int zero = 0;
|
|
static struct ctl_table pid_ns_ctl_table[] = {
|
|
{
|
|
.procname = "ns_last_pid",
|
|
.maxlen = sizeof(int),
|
|
.mode = 0666, /* permissions are checked in the handler */
|
|
.proc_handler = pid_ns_ctl_handler,
|
|
.extra1 = &zero,
|
|
.extra2 = &pid_max,
|
|
},
|
|
{ }
|
|
};
|
|
static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } };
|
|
#endif /* CONFIG_CHECKPOINT_RESTORE */
|
|
|
|
int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
|
|
{
|
|
if (pid_ns == &init_pid_ns)
|
|
return 0;
|
|
|
|
switch (cmd) {
|
|
case LINUX_REBOOT_CMD_RESTART2:
|
|
case LINUX_REBOOT_CMD_RESTART:
|
|
pid_ns->reboot = SIGHUP;
|
|
break;
|
|
|
|
case LINUX_REBOOT_CMD_POWER_OFF:
|
|
case LINUX_REBOOT_CMD_HALT:
|
|
pid_ns->reboot = SIGINT;
|
|
break;
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
|
|
read_lock(&tasklist_lock);
|
|
force_sig(SIGKILL, pid_ns->child_reaper);
|
|
read_unlock(&tasklist_lock);
|
|
|
|
do_exit(0);
|
|
|
|
/* Not reached */
|
|
return 0;
|
|
}
|
|
|
|
static __init int pid_namespaces_init(void)
|
|
{
|
|
pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
|
|
|
|
#ifdef CONFIG_CHECKPOINT_RESTORE
|
|
register_sysctl_paths(kern_path, pid_ns_ctl_table);
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
__initcall(pid_namespaces_init);
|