/* * 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> #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);} void zap_pid_ns_processes(struct pid_namespace *pid_ns){	int nr;	int rc;	struct task_struct *task; 	/*	 * 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(); 		/*		 * Any nested-container's init processes won't ignore the		 * SEND_SIG_NOINFO signal, see send_signal()->si_fromuser().		 */		task = pid_task(find_vpid(nr), PIDTYPE_PID);		if (task)			send_sig_info(SIGKILL, SEND_SIG_NOINFO, task); 		rcu_read_unlock(); 		nr = next_pidmap(pid_ns, nr);	}	read_unlock(&tasklist_lock); 	do {		clear_thread_flag(TIF_SIGPENDING);		rc = sys_wait4(-1, NULL, __WALL, NULL);	} while (rc != -ECHILD); 	acct_exit_ns(pid_ns);	return;} 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 = &current->nsproxy->pid_ns->last_pid;	return proc_dointvec(&tmp, write, buffer, lenp, ppos);} 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,	},	{ }}; static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } }; static __init int pid_namespaces_init(void){	pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);	register_sysctl_paths(kern_path, pid_ns_ctl_table);	return 0;} __initcall(pid_namespaces_init);