path: root/net/core/net_namespace.c

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/workqueue.h>
#include <linux/rtnetlink.h>
#include <linux/cache.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/idr.h>
#include <linux/rculist.h>
#include <linux/nsproxy.h>
#include <linux/fs.h>
#include <linux/proc_ns.h>
#include <linux/file.h>
#include <linux/export.h>
#include <linux/user_namespace.h>
#include <linux/net_namespace.h>
#include <net/sock.h>
#include <net/netlink.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>

/*
 *	Our network namespace constructor/destructor lists
 */

static LIST_HEAD(pernet_list);
static struct list_head *first_device = &pernet_list;
DEFINE_MUTEX(net_mutex);

LIST_HEAD(net_namespace_list);
EXPORT_SYMBOL_GPL(net_namespace_list);

struct net init_net = {
	.dev_base_head = LIST_HEAD_INIT(init_net.dev_base_head),
};
EXPORT_SYMBOL(init_net);

#define INITIAL_NET_GEN_PTRS	13 /* +1 for len +2 for rcu_head */

static unsigned int max_gen_ptrs = INITIAL_NET_GEN_PTRS;

static struct net_generic *net_alloc_generic(void)
{
	struct net_generic *ng;
	size_t generic_size = offsetof(struct net_generic, ptr[max_gen_ptrs]);

	ng = kzalloc(generic_size, GFP_KERNEL);
	if (ng)
		ng->len = max_gen_ptrs;

	return ng;
}

static int net_assign_generic(struct net *net, int id, void *data)
{
	struct net_generic *ng, *old_ng;

	BUG_ON(!mutex_is_locked(&net_mutex));
	BUG_ON(id == 0);

	old_ng = rcu_dereference_protected(net->gen,
					   lockdep_is_held(&net_mutex));
	ng = old_ng;
	if (old_ng->len >= id)
		goto assign;

	ng = net_alloc_generic();
	if (ng == NULL)
		return -ENOMEM;

	/*
	 * Some synchronisation notes:
	 *
	 * The net_generic explores the net->gen array inside rcu
	 * read section. Besides once set the net->gen->ptr[x]
	 * pointer never changes (see rules in netns/generic.h).
	 *
	 * That said, we simply duplicate this array and schedule
	 * the old copy for kfree after a grace period.
	 */

	memcpy(&ng->ptr, &old_ng->ptr, old_ng->len * sizeof(void*));

	rcu_assign_pointer(net->gen, ng);
	kfree_rcu(old_ng, rcu);
assign:
	ng->ptr[id - 1] = data;
	return 0;
}

static int ops_init(const struct pernet_operations *ops, struct net *net)
{
	int err = -ENOMEM;
	void *data = NULL;

	if (ops->id && ops->size) {
		data = kzalloc(ops->size, GFP_KERNEL);
		if (!data)
			goto out;

		err = net_assign_generic(net, *ops->id, data);
		if (err)
			goto cleanup;
	}
	err = 0;
	if (ops->init)
		err = ops->init(net);
	if (!err)
		return 0;

cleanup:
	kfree(data);

out:
	return err;
}

static void ops_free(const struct pernet_operations *ops, struct net *net)
{
	if (ops->id && ops->size) {
		int id = *ops->id;
		kfree(net_generic(net, id));
	}
}

static void ops_exit_list(const struct pernet_operations *ops,
			  struct list_head *net_exit_list)
{
	struct net *net;
	if (ops->exit) {
		list_for_each_entry(net, net_exit_list, exit_list)
			ops->exit(net);
	}
	if (ops->exit_batch)
		ops->exit_batch(net_exit_list);
}

static void ops_free_list(const struct pernet_operations *ops,
			  struct list_head *net_exit_list)
{
	struct net *net;
	if (ops->size && ops->id) {
		list_for_each_entry(net, net_exit_list, exit_list)
			ops_free(ops, net);
	}
}

/* should be called with nsid_lock held */
static int alloc_netid(struct net *net, struct net *peer, int reqid)
{
	int min = 0, max = 0;

	if (reqid >= 0) {
		min = reqid;
		max = reqid + 1;
	}

	return idr_alloc(&net->netns_ids, peer, min, max, GFP_ATOMIC);
}

/* This function is used by idr_for_each(). If net is equal to peer, the
 * function returns the id so that idr_for_each() stops. Because we cannot
 * returns the id 0 (idr_for_each() will not stop), we return the magic value
 * NET_ID_ZERO (-1) for it.
 */
#define NET_ID_ZERO -1
static int net_eq_idr(int id, void *net, void *peer)
{
	if (net_eq(net, peer))
		return id ? : NET_ID_ZERO;
	return 0;
}

/* Should be called with nsid_lock held. If a new id is assigned, the bool alloc
 * is set to true, thus the caller knows that the new id must be notified via
 * rtnl.
 */
static int __peernet2id_alloc(struct net *net, struct net *peer, bool *alloc)
{
	int id = idr_for_each(&net->netns_ids, net_eq_idr, peer);
	bool alloc_it = *alloc;

	*alloc = false;

	/* Magic value for id 0. */
	if (id == NET_ID_ZERO)
		return 0;
	if (id > 0)
		return id;

	if (alloc_it) {
		id = alloc_netid(net, peer, -1);
		*all