1 files changed, 1400 insertions, 0 deletions

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
new file mode 100644
index 000000000..f4183c4c1
--- /dev/null
+++ b/net/core/net_namespace.c
@@ -0,0 +1,1400 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#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 <linux/sched/task.h>
+#include <linux/uidgid.h>
+#include <linux/cookie.h>
+#include <linux/proc_fs.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;
+
+LIST_HEAD(net_namespace_list);
+EXPORT_SYMBOL_GPL(net_namespace_list);
+
+/* Protects net_namespace_list. Nests iside rtnl_lock() */
+DECLARE_RWSEM(net_rwsem);
+EXPORT_SYMBOL_GPL(net_rwsem);
+
+#ifdef CONFIG_KEYS
+static struct key_tag init_net_key_domain = { .usage = REFCOUNT_INIT(1) };
+#endif
+
+struct net init_net;
+EXPORT_SYMBOL(init_net);
+
+static bool init_net_initialized;
+/*
+ * pernet_ops_rwsem: protects: pernet_list, net_generic_ids,
+ * init_net_initialized and first_device pointer.
+ * This is internal net namespace object. Please, don't use it
+ * outside.
+ */
+DECLARE_RWSEM(pernet_ops_rwsem);
+EXPORT_SYMBOL_GPL(pernet_ops_rwsem);
+
+#define MIN_PERNET_OPS_ID	\
+	((sizeof(struct net_generic) + sizeof(void *) - 1) / sizeof(void *))
+
+#define INITIAL_NET_GEN_PTRS	13 /* +1 for len +2 for rcu_head */
+
+static unsigned int max_gen_ptrs = INITIAL_NET_GEN_PTRS;
+
+DEFINE_COOKIE(net_cookie);
+
+static struct net_generic *net_alloc_generic(void)
+{
+	struct net_generic *ng;
+	unsigned int generic_size = offsetof(struct net_generic, ptr[max_gen_ptrs]);
+
+	ng = kzalloc(generic_size, GFP_KERNEL);
+	if (ng)
+		ng->s.len = max_gen_ptrs;
+
+	return ng;
+}
+
+static int net_assign_generic(struct net *net, unsigned int id, void *data)
+{
+	struct net_generic *ng, *old_ng;
+
+	BUG_ON(id < MIN_PERNET_OPS_ID);
+
+	old_ng = rcu_dereference_protected(net->gen,
+					   lockdep_is_held(&pernet_ops_rwsem));
+	if (old_ng->s.len > id) {
+		old_ng->ptr[id] = data;
+		return 0;
+	}
+
+	ng = net_alloc_generic();
+	if (!ng)
+		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[MIN_PERNET_OPS_ID], &old_ng->ptr[MIN_PERNET_OPS_ID],
+	       (old_ng->s.len - MIN_PERNET_OPS_ID) * sizeof(void *));
+	ng->ptr[id] = data;
+
+	rcu_assign_pointer(net->gen, ng);
+	kfree_rcu(old_ng, s.rcu);
+	return 0;
+}
+
+static int ops_init(const struct pernet_operations *ops, struct net *net)
+{
+	struct net_generic *ng;
+	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;
+
+	if (ops->id && ops->size) {
+		ng = rcu_dereference_protected(net->gen,
+					       lockdep_is_held(&pernet_ops_rwsem));
+		ng->ptr[*ops->id] = NULL;
+	}
+
+cleanup:
+	kfree(data);
+
+out:
+	return err;
+}
+
+static void ops_pre_exit_list(const struct pernet_operations *ops,
+			      struct list_head *net_exit_list)
+{
+	struct net *net;
+
+	if (ops->pre_exit) {
+		list_for_each_entry(net, net_exit_list, exit_list)
+			ops->pre_exit(net);
+	}
+}
+
+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);
+			cond_resched();
+		}
+	}
+	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)
+			kfree(net_generic(net, *ops->id));
+	}
+}
+
+/* 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;
+}
+
+/* Must be called from RCU-critical section or with nsid_lock held */
+static int __peernet2id(const struct net *net, struct net *peer)
+{
+	int id = idr_for_each(&net->netns_ids, net_eq_idr, peer);
+
+	/* Magic value for id 0. */
+	if (id == NET_ID_ZERO)
+		return 0;
+	if (id > 0)
+		return id;
+
+	return NETNSA_NSID_NOT_ASSIGNED;
+}
+
+static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
+			      struct nlmsghdr *nlh, gfp_t gfp);
+/* This function returns the id of a peer netns. If no id is assigned, one will
+ * be allocated and returned.
+ */
+int peernet2id_alloc(struct net *net, struct net *peer, gfp_t gfp)
+{
+	int id;
+
+	if (refcount_read(&net->ns.count) == 0)
+		return NETNSA_NSID_NOT_ASSIGNED;
+
+	spin_lock_bh(&net->nsid_lock);
+	id = __peernet2id(net, peer);
+	if (id >= 0) {
+		spin_unlock_bh(&net->nsid_lock);
+		return id;
+	}
+
+	/* When peer is obtained from RCU lists, we may race with
+	 * its cleanup. Check whether it's alive, and this guarantees
+	 * we never hash a peer back to net->netns_ids, after it has
+	 * just been idr_remove()'d from there in cleanup_net().
+	 */
+	if (!maybe_get_net(peer)) {
+		spin_unlock_bh(&net->nsid_lock);
+		return NETNSA_NSID_NOT_ASSIGNED;
+	}
+
+	id = alloc_netid(net, peer, -1);
+	spin_unlock_bh(&net->nsid_lock);
+
+	put_net(peer);
+	if (id < 0)
+		return NETNSA_NSID_NOT_ASSIGNED;
+
+	rtnl_net_notifyid(net, RTM_NEWNSID, id, 0, NULL, gfp);
+
+	return id;
+}
+EXPORT_SYMBOL_GPL(peernet2id_alloc);
+
+/* This function returns, if assigned, the id of a peer netns. */
+int peernet2id(const struct net *net, struct net *peer)
+{
+	int id;
+
+	rcu_read_lock();
+	id = __peernet2id(net, peer);
+	rcu_read_unlock();
+
+	return id;
+}
+EXPORT_SYMBOL(peernet2id);
+
+/* This function returns true is the peer netns has an id assigned into the
+ * current netns.
+ */
+bool peernet_has_id(const struct net *net, struct net *peer)
+{
+	return peernet2id(net, peer) >= 0;
+}
+
+struct net *get_net_ns_by_id(const struct net *net, int id)
+{
+	struct net *peer;
+
+	if (id < 0)
+		return NULL;
+
+	rcu_read_lock();
+	peer = idr_find(&net->netns_ids, id);
+	if (peer)
+		peer = maybe_get_net(peer);
+	rcu_read_unlock();
+
+	return peer;
+}
+EXPORT_SYMBOL_GPL(get_net_ns_by_id);
+
+/* init code that must occur even if setup_net() is not called. */
+static __net_init void preinit_net(struct net *net)
+{
+	ref_tracker_dir_init(&net->notrefcnt_tracker, 128, "net notrefcnt");
+}
+
+/*
+ * setup_net runs the initializers for the network namespace object.
+ */
+static __net_init int setup_net(struct net *net, struct user_namespace *user_ns)
+{
+	/* Must be called with pernet_ops_rwsem held */
+	const struct pernet_operations *ops, *saved_ops;
+	int error = 0;
+	LIST_HEAD(net_exit_list);
+
+	refcount_set(&net->ns.count, 1);
+	ref_tracker_dir_init(&net->refcnt_tracker, 128, "net refcnt");
+
+	refcount_set(&net->passive, 1);
+	get_random_bytes(&net->hash_mix, sizeof(u32));
+	preempt_disable();
+	net->net_cookie = gen_cookie_next(&net_cookie);
+	preempt_enable();
+	net->dev_base_seq = 1;
+	net->user_ns = user_ns;
+	idr_init(&net->netns_ids);
+	spin_lock_init(&net->nsid_lock);
+	mutex_init(&net->ipv4.ra_mutex);
+
+	list_for_each_entry(ops, &pernet_list, list) {
+		error = ops_init(ops, net);
+		if (error < 0)
+			goto out_undo;
+	}
+	down_write(&net_rwsem);
+	list_add_tail_rcu(&net->list, &net_namespace_list);
+	up_write(&net_rwsem);
+out:
+	return error;
+
+out_undo:
+	/* Walk through the list backwards calling the exit functions
+	 * for the pernet modules whose init functions did not fail.
+	 */
+	list_add(&net->exit_list, &net_exit_list);
+	saved_ops = ops;
+	list_for_each_entry_continue_reverse(ops, &pernet_list, list)
+		ops_pre_exit_list(ops, &net_exit_list);
+
+	synchronize_rcu();
+
+	ops = saved_ops;
+	list_for_each_entry_continue_reverse(ops, &pernet_list, list)
+		ops_exit_list(ops, &net_exit_list);
+
+	ops = saved_ops;
+	list_for_each_entry_continue_reverse(ops, &pernet_list, list)
+		ops_free_list(ops, &net_exit_list);
+
+	rcu_barrier();
+	goto out;
+}
+
+static int __net_init net_defaults_init_net(struct net *net)
+{
+	net->core.sysctl_somaxconn = SOMAXCONN;
+	net->core.sysctl_txrehash = SOCK_TXREHASH_ENABLED;
+
+	return 0;
+}
+
+static struct pernet_operations net_defaults_ops = {
+	.init = net_defaults_init_net,
+};
+
+static __init int net_defaults_init(void)
+{
+	if (register_pernet_subsys(&net_defaults_ops))
+		panic("Cannot initialize net default settings");
+
+	return 0;
+}
+
+core_initcall(net_defaults_init);
+
+#ifdef CONFIG_NET_NS
+static struct ucounts *inc_net_namespaces(struct user_namespace *ns)
+{
+	return inc_ucount(ns, current_euid(), UCOUNT_NET_NAMESPACES);
+}
+
+static void dec_net_namespaces(struct ucounts *ucounts)
+{
+	dec_ucount(ucounts, UCOUNT_NET_NAMESPACES);
+}
+
+static struct kmem_cache *net_cachep __ro_after_init;
+static struct workqueue_struct *netns_wq;
+
+static struct net *net_alloc(void)
+{
+	struct net *net = NULL;
+	struct net_generic *ng;
+
+	ng = net_alloc_generic();
+	if (!ng)
+		goto out;
+
+	net = kmem_cache_zalloc(net_cachep, GFP_KERNEL);
+	if (!net)
+		goto out_free;
+
+#ifdef CONFIG_KEYS
+	net->key_domain = kzalloc(sizeof(struct key_tag), GFP_KERNEL);
+	if (!net->key_domain)
+		goto out_free_2;
+	refcount_set(&net->key_domain->usage, 1);
+#endif
+
+	rcu_assign_pointer(net->gen, ng);
+out:
+	return net;
+
+#ifdef CONFIG_KEYS
+out_free_2:
+	kmem_cache_free(net_cachep, net);
+	net = NULL;
+#endif
+out_free:
+	kfree(ng);
+	goto out;
+}
+
+static void net_free(struct net *net)
+{
+	if (refcount_dec_and_test(&net->passive)) {
+		kfree(rcu_access_pointer(net->gen));
+
+		/* There should not be any trackers left there. */
+		ref_tracker_dir_exit(&net->notrefcnt_tracker);
+
+		kmem_cache_free(net_cachep, net);
+	}
+}
+
+void net_drop_ns(void *p)
+{
+	struct net *net = (struct net *)p;
+
+	if (net)
+		net_free(net);
+}
+
+struct net *copy_net_ns(unsigned long flags,
+			struct user_namespace *user_ns, struct net *old_net)
+{
+	struct ucounts *ucounts;
+	struct net *net;
+	int rv;
+
+	if (!(flags & CLONE_NEWNET))
+		return get_net(old_net);
+
+	ucounts = inc_net_namespaces(user_ns);
+	if (!ucounts)
+		return ERR_PTR(-ENOSPC);
+
+	net = net_alloc();
+	if (!net) {
+		rv = -ENOMEM;
+		goto dec_ucounts;
+	}
+
+	preinit_net(net);
+	refcount_set(&net->passive, 1);
+	net->ucounts = ucounts;
+	get_user_ns(user_ns);
+
+	rv = down_read_killable(&pernet_ops_rwsem);
+	if (rv < 0)
+		goto put_userns;
+
+	rv = setup_net(net, user_ns);
+
+	up_read(&pernet_ops_rwsem);
+
+	if (rv < 0) {
+put_userns:
+#ifdef CONFIG_KEYS
+		key_remove_domain(net->key_domain);
+#endif
+		put_user_ns(user_ns);
+		net_free(net);
+dec_ucounts:
+		dec_net_namespaces(ucounts);
+		return ERR_PTR(rv);
+	}
+	return net;
+}
+
+/**
+ * net_ns_get_ownership - get sysfs ownership data for @net
+ * @net: network namespace in question (can be NULL)
+ * @uid: kernel user ID for sysfs objects
+ * @gid: kernel group ID for sysfs objects
+ *
+ * Returns the uid/gid pair of root in the user namespace associated with the
+ * given network namespace.
+ */
+void net_ns_get_ownership(const struct net *net, kuid_t *uid, kgid_t *gid)
+{
+	if (net) {
+		kuid_t ns_root_uid = make_kuid(net->user_ns, 0);
+		kgid_t ns_root_gid = make_kgid(net->user_ns, 0);
+
+		if (uid_valid(ns_root_uid))
+			*uid = ns_root_uid;
+
+		if (gid_valid(ns_root_gid))
+			*gid = ns_root_gid;
+	} else {
+		*uid = GLOBAL_ROOT_UID;
+		*gid = GLOBAL_ROOT_GID;
+	}
+}
+EXPORT_SYMBOL_GPL(net_ns_get_ownership);
+
+static void unhash_nsid(struct net *net, struct net *last)
+{
+	struct net *tmp;
+	/* This function is only called from cleanup_net() work,
+	 * and this work is the only process, that may delete
+	 * a net from net_namespace_list. So, when the below
+	 * is executing, the list may only grow. Thus, we do not
+	 * use for_each_net_rcu() or net_rwsem.
+	 */
+	for_each_net(tmp) {
+		int id;
+
+		spin_lock_bh(&tmp->nsid_lock);
+		id = __peernet2id(tmp, net);
+		if (id >= 0)
+			idr_remove(&tmp->netns_ids, id);
+		spin_unlock_bh(&tmp->nsid_lock);
+		if (id >= 0)
+			rtnl_net_notifyid(tmp, RTM_DELNSID, id, 0, NULL,
+					  GFP_KERNEL);
+		if (tmp == last)
+			break;
+	}
+	spin_lock_bh(&net->nsid_lock);
+	idr_destroy(&net->netns_ids);
+	spin_unlock_bh(&net->nsid_lock);
+}
+
+static LLIST_HEAD(cleanup_list);
+
+static void cleanup_net(struct work_struct *work)
+{
+	const struct pernet_operations *ops;
+	struct net *net, *tmp, *last;
+	struct llist_node *net_kill_list;
+	LIST_HEAD(net_exit_list);
+
+	/* Atomically snapshot the list of namespaces to cleanup */
+	net_kill_list = llist_del_all(&cleanup_list);
+
+	down_read(&pernet_ops_rwsem);
+
+	/* Don't let anyone else find us. */
+	down_write(&net_rwsem);
+	llist_for_each_entry(net, net_kill_list, cleanup_list)
+		list_del_rcu(&net->list);
+	/* Cache last net. After we unlock rtnl, no one new net
+	 * added to net_namespace_list can assign nsid pointer
+	 * to a net from net_kill_list (see peernet2id_alloc()).
+	 * So, we skip them in unhash_nsid().
+	 *
+	 * Note, that unhash_nsid() does not delete nsid links
+	 * between net_kill_list's nets, as they've already
+	 * deleted from net_namespace_list. But, this would be
+	 * useless anyway, as netns_ids are destroyed there.
+	 */
+	last = list_last_entry(&net_namespace_list, struct net, list);
+	up_write(&net_rwsem);
+
+	llist_for_each_entry(net, net_kill_list, cleanup_list) {
+		unhash_nsid(net, last);
+		list_add_tail(&net->exit_list, &net_exit_list);
+	}
+
+	/* Run all of the network namespace pre_exit methods */
+	list_for_each_entry_reverse(ops, &pernet_list, list)
+		ops_pre_exit_list(ops, &net_exit_list);
+
+	/*
+	 * Another CPU might be rcu-iterating the list, wait for it.
+	 * This needs to be before calling the exit() notifiers, so
+	 * the rcu_barrier() below isn't sufficient alone.
+	 * Also the pre_exit() and exit() methods need this barrier.
+	 */
+	synchronize_rcu();
+
+	/* Run all of the network namespace exit methods */
+	list_for_each_entry_reverse(ops, &pernet_list, list)
+		ops_exit_list(ops, &net_exit_list);
+
+	/* Free the net generic variables */
+	list_for_each_entry_reverse(ops, &pernet_list, list)
+		ops_free_list(ops, &net_exit_list);
+
+	up_read(&pernet_ops_rwsem);
+
+	/* Ensure there are no outstanding rcu callbacks using this
+	 * network namespace.
+	 */
+	rcu_barrier();
+
+	/* Finally it is safe to free my network namespace structure */
+	list_for_each_entry_safe(net, tmp, &net_exit_list, exit_list) {
+		list_del_init(&net->exit_list);
+		dec_net_namespaces(net->ucounts);
+#ifdef CONFIG_KEYS
+		key_remove_domain(net->key_domain);
+#endif
+		put_user_ns(net->user_ns);
+		net_free(net);
+	}
+}
+
+/**
+ * net_ns_barrier - wait until concurrent net_cleanup_work is done
+ *
+ * cleanup_net runs from work queue and will first remove namespaces
+ * from the global list, then run net exit functions.
+ *
+ * Call this in module exit path to make sure that all netns
+ * ->exit ops have been invoked before the function is removed.
+ */
+void net_ns_barrier(void)
+{
+	down_write(&pernet_ops_rwsem);
+	up_write(&pernet_ops_rwsem);
+}
+EXPORT_SYMBOL(net_ns_barrier);
+
+static DECLARE_WORK(net_cleanup_work, cleanup_net);
+
+void __put_net(struct net *net)
+{
+	ref_tracker_dir_exit(&net->refcnt_tracker);
+	/* Cleanup the network namespace in process context */
+	if (llist_add(&net->cleanup_list, &cleanup_list))
+		queue_work(netns_wq, &net_cleanup_work);
+}
+EXPORT_SYMBOL_GPL(__put_net);
+
+/**
+ * get_net_ns - increment the refcount of the network namespace
+ * @ns: common namespace (net)
+ *
+ * Returns the net's common namespace.
+ */
+struct ns_common *get_net_ns(struct ns_common *ns)
+{
+	return &get_net(container_of(ns, struct net, ns))->ns;
+}
+EXPORT_SYMBOL_GPL(get_net_ns);
+
+struct net *get_net_ns_by_fd(int fd)
+{
+	struct fd f = fdget(fd);
+	struct net *net = ERR_PTR(-EINVAL);
+
+	if (!f.file)
+		return ERR_PTR(-EBADF);
+
+	if (proc_ns_file(f.file)) {
+		struct ns_common *ns = get_proc_ns(file_inode(f.file));
+		if (ns->ops == &netns_operations)
+			net = get_net(container_of(ns, struct net, ns));
+	}
+	fdput(f);
+
+	return net;
+}
+EXPORT_SYMBOL_GPL(get_net_ns_by_fd);
+#endif
+
+struct net *get_net_ns_by_pid(pid_t pid)
+{
+	struct task_struct *tsk;
+	struct net *net;
+
+	/* Lookup the network namespace */
+	net = ERR_PTR(-ESRCH);
+	rcu_read_lock();
+	tsk = find_task_by_vpid(pid);
+	if (tsk) {
+		struct nsproxy *nsproxy;
+		task_lock(tsk);
+		nsproxy = tsk->nsproxy;
+		if (nsproxy)
+			net = get_net(nsproxy->net_ns);
+		task_unlock(tsk);
+	}
+	rcu_read_unlock();
+	return net;
+}
+EXPORT_SYMBOL_GPL(get_net_ns_by_pid);
+
+static __net_init int net_ns_net_init(struct net *net)
+{
+#ifdef CONFIG_NET_NS
+	net->ns.ops = &netns_operations;
+#endif
+	return ns_alloc_inum(&net->ns);
+}
+
+static __net_exit void net_ns_net_exit(struct net *net)
+{
+	ns_free_inum(&net->ns);
+}
+
+static struct pernet_operations __net_initdata net_ns_ops = {
+	.init = net_ns_net_init,
+	.exit = net_ns_net_exit,
+};
+
+static const struct nla_policy rtnl_net_policy[NETNSA_MAX + 1] = {
+	[NETNSA_NONE]		= { .type = NLA_UNSPEC },
+	[NETNSA_NSID]		= { .type = NLA_S32 },
+	[NETNSA_PID]		= { .type = NLA_U32 },
+	[NETNSA_FD]		= { .type = NLA_U32 },
+	[NETNSA_TARGET_NSID]	= { .type = NLA_S32 },
+};
+
+static int rtnl_net_newid(struct sk_buff *skb, struct nlmsghdr *nlh,
+			  struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(skb->sk);
+	struct nlattr *tb[NETNSA_MAX + 1];
+	struct nlattr *nla;
+	struct net *peer;
+	int nsid, err;
+
+	err = nlmsg_parse_deprecated(nlh, sizeof(struct rtgenmsg), tb,
+				     NETNSA_MAX, rtnl_net_policy, extack);
+	if (err < 0)
+		return err;
+	if (!tb[NETNSA_NSID]) {
+		NL_SET_ERR_MSG(extack, "nsid is missing");
+		return -EINVAL;
+	}
+	nsid = nla_get_s32(tb[NETNSA_NSID]);
+
+	if (tb[NETNSA_PID]) {
+		peer = get_net_ns_by_pid(nla_get_u32(tb[NETNSA_PID]));
+		nla = tb[NETNSA_PID];
+	} else if (tb[NETNSA_FD]) {
+		peer = get_net_ns_by_fd(nla_get_u32(tb[NETNSA_FD]));
+		nla = tb[NETNSA_FD];
+	} else {
+		NL_SET_ERR_MSG(extack, "Peer netns reference is missing");
+		return -EINVAL;
+	}
+	if (IS_ERR(peer)) {
+		NL_SET_BAD_ATTR(extack, nla);
+		NL_SET_ERR_MSG(extack, "Peer netns reference is invalid");
+		return PTR_ERR(peer);
+	}
+
+	spin_lock_bh(&net->nsid_lock);
+	if (__peernet2id(net, peer) >= 0) {
+		spin_unlock_bh(&net->nsid_lock);
+		err = -EEXIST;
+		NL_SET_BAD_ATTR(extack, nla);
+		NL_SET_ERR_MSG(extack,
+			       "Peer netns already has a nsid assigned");
+		goto out;
+	}
+
+	err = alloc_netid(net, peer, nsid);
+	spin_unlock_bh(&net->nsid_lock);
+	if (err >= 0) {
+		rtnl_net_notifyid(net, RTM_NEWNSID, err, NETLINK_CB(skb).portid,
+				  nlh, GFP_KERNEL);
+		err = 0;
+	} else if (err == -ENOSPC && nsid >= 0) {
+		err = -EEXIST;
+		NL_SET_BAD_ATTR(extack, tb[NETNSA_NSID]);
+		NL_SET_ERR_MSG(extack, "The specified nsid is already used");
+	}
+out:
+	put_net(peer);
+	return err;
+}
+
+static int rtnl_net_get_size(void)
+{
+	return NLMSG_ALIGN(sizeof(struct rtgenmsg))
+	       + nla_total_size(sizeof(s32)) /* NETNSA_NSID */
+	       + nla_total_size(sizeof(s32)) /* NETNSA_CURRENT_NSID */
+	       ;
+}
+
+struct net_fill_args {
+	u32 portid;
+	u32 seq;
+	int flags;
+	int cmd;
+	int nsid;
+	bool add_ref;
+	int ref_nsid;
+};
+
+static int rtnl_net_fill(struct sk_buff *skb, struct net_fill_args *args)
+{
+	struct nlmsghdr *nlh;
+	struct rtgenmsg *rth;
+
+	nlh = nlmsg_put(skb, args->portid, args->seq, args->cmd, sizeof(*rth),
+			args->flags);
+	if (!nlh)
+		return -EMSGSIZE;
+
+	rth = nlmsg_data(nlh);
+	rth->rtgen_family = AF_UNSPEC;
+
+	if (nla_put_s32(skb, NETNSA_NSID, args->nsid))
+		goto nla_put_failure;
+
+	if (args->add_ref &&
+	    nla_put_s32(skb, NETNSA_CURRENT_NSID, args->ref_nsid))
+		goto nla_put_failure;
+
+	nlmsg_end(skb, nlh);
+	return 0;
+
+nla_put_failure:
+	nlmsg_cancel(skb, nlh);
+	return -EMSGSIZE;
+}
+
+static int rtnl_net_valid_getid_req(struct sk_buff *skb,
+				    const struct nlmsghdr *nlh,
+				    struct nlattr **tb,
+				    struct netlink_ext_ack *extack)
+{
+	int i, err;
+
+	if (!netlink_strict_get_check(skb))
+		return nlmsg_parse_deprecated(nlh, sizeof(struct rtgenmsg),
+					      tb, NETNSA_MAX, rtnl_net_policy,
+					      extack);
+
+	err = nlmsg_parse_deprecated_strict(nlh, sizeof(struct rtgenmsg), tb,
+					    NETNSA_MAX, rtnl_net_policy,
+					    extack);
+	if (err)
+		return err;
+
+	for (i = 0; i <= NETNSA_MAX; i++) {
+		if (!tb[i])
+			continue;
+
+		switch (i) {
+		case NETNSA_PID:
+		case NETNSA_FD:
+		case NETNSA_NSID:
+		case NETNSA_TARGET_NSID:
+			break;
+		default:
+			NL_SET_ERR_MSG(extack, "Unsupported attribute in peer netns getid request");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static int rtnl_net_getid(struct sk_buff *skb, struct nlmsghdr *nlh,
+			  struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(skb->sk);
+	struct nlattr *tb[NETNSA_MAX + 1];
+	struct net_fill_args fillargs = {
+		.portid = NETLINK_CB(skb).portid,
+		.seq = nlh->nlmsg_seq,
+		.cmd = RTM_NEWNSID,
+	};
+	struct net *peer, *target = net;
+	struct nlattr *nla;
+	struct sk_buff *msg;
+	int err;
+
+	err = rtnl_net_valid_getid_req(skb, nlh, tb, extack);
+	if (err < 0)
+		return err;
+	if (tb[NETNSA_PID]) {
+		peer = get_net_ns_by_pid(nla_get_u32(tb[NETNSA_PID]));
+		nla = tb[NETNSA_PID];
+	} else if (tb[NETNSA_FD]) {
+		peer = get_net_ns_by_fd(nla_get_u32(tb[NETNSA_FD]));
+		nla = tb[NETNSA_FD];
+	} else if (tb[NETNSA_NSID]) {
+		peer = get_net_ns_by_id(net, nla_get_s32(tb[NETNSA_NSID]));
+		if (!peer)
+			peer = ERR_PTR(-ENOENT);
+		nla = tb[NETNSA_NSID];
+	} else {
+		NL_SET_ERR_MSG(extack, "Peer netns reference is missing");
+		return -EINVAL;
+	}
+
+	if (IS_ERR(peer)) {
+		NL_SET_BAD_ATTR(extack, nla);
+		NL_SET_ERR_MSG(extack, "Peer netns reference is invalid");
+		return PTR_ERR(peer);
+	}
+
+	if (tb[NETNSA_TARGET_NSID]) {
+		int id = nla_get_s32(tb[NETNSA_TARGET_NSID]);
+
+		target = rtnl_get_net_ns_capable(NETLINK_CB(skb).sk, id);
+		if (IS_ERR(target)) {
+			NL_SET_BAD_ATTR(extack, tb[NETNSA_TARGET_NSID]);
+			NL_SET_ERR_MSG(extack,
+				       "Target netns reference is invalid");
+			err = PTR_ERR(target);
+			goto out;
+		}
+		fillargs.add_ref = true;
+		fillargs.ref_nsid = peernet2id(net, peer);
+	}
+
+	msg = nlmsg_new(rtnl_net_get_size(), GFP_KERNEL);
+	if (!msg) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	fillargs.nsid = peernet2id(target, peer);
+	err = rtnl_net_fill(msg, &fillargs);
+	if (err < 0)
+		goto err_out;
+
+	err = rtnl_unicast(msg, net, NETLINK_CB(skb).portid);
+	goto out;
+
+err_out:
+	nlmsg_free(msg);
+out:
+	if (fillargs.add_ref)
+		put_net(target);
+	put_net(peer);
+	return err;
+}
+
+struct rtnl_net_dump_cb {
+	struct net *tgt_net;
+	struct net *ref_net;
+	struct sk_buff *skb;
+	struct net_fill_args fillargs;
+	int idx;
+	int s_idx;
+};
+
+/* Runs in RCU-critical section. */
+static int rtnl_net_dumpid_one(int id, void *peer, void *data)
+{
+	struct rtnl_net_dump_cb *net_cb = (struct rtnl_net_dump_cb *)data;
+	int ret;
+
+	if (net_cb->idx < net_cb->s_idx)
+		goto cont;
+
+	net_cb->fillargs.nsid = id;
+	if (net_cb->fillargs.add_ref)
+		net_cb->fillargs.ref_nsid = __peernet2id(net_cb->ref_net, peer);
+	ret = rtnl_net_fill(net_cb->skb, &net_cb->fillargs);
+	if (ret < 0)
+		return ret;
+
+cont:
+	net_cb->idx++;
+	return 0;
+}
+
+static int rtnl_valid_dump_net_req(const struct nlmsghdr *nlh, struct sock *sk,
+				   struct rtnl_net_dump_cb *net_cb,
+				   struct netlink_callback *cb)
+{
+	struct netlink_ext_ack *extack = cb->extack;
+	struct nlattr *tb[NETNSA_MAX + 1];
+	int err, i;
+
+	err = nlmsg_parse_deprecated_strict(nlh, sizeof(struct rtgenmsg), tb,
+					    NETNSA_MAX, rtnl_net_policy,
+					    extack);
+	if (err < 0)
+		return err;
+
+	for (i = 0; i <= NETNSA_MAX; i++) {
+		if (!tb[i])
+			continue;
+
+		if (i == NETNSA_TARGET_NSID) {
+			struct net *net;
+
+			net = rtnl_get_net_ns_capable(sk, nla_get_s32(tb[i]));
+			if (IS_ERR(net)) {
+				NL_SET_BAD_ATTR(extack, tb[i]);
+				NL_SET_ERR_MSG(extack,
+					       "Invalid target network namespace id");
+				return PTR_ERR(net);
+			}
+			net_cb->fillargs.add_ref = true;
+			net_cb->ref_net = net_cb->tgt_net;
+			net_cb->tgt_net = net;
+		} else {
+			NL_SET_BAD_ATTR(extack, tb[i]);
+			NL_SET_ERR_MSG(extack,
+				       "Unsupported attribute in dump request");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static int rtnl_net_dumpid(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	struct rtnl_net_dump_cb net_cb = {
+		.tgt_net = sock_net(skb->sk),
+		.skb = skb,
+		.fillargs = {
+			.portid = NETLINK_CB(cb->skb).portid,
+			.seq = cb->nlh->nlmsg_seq,
+			.flags = NLM_F_MULTI,
+			.cmd = RTM_NEWNSID,
+		},
+		.idx = 0,
+		.s_idx = cb->args[0],
+	};
+	int err = 0;
+
+	if (cb->strict_check) {
+		err = rtnl_valid_dump_net_req(cb->nlh, skb->sk, &net_cb, cb);
+		if (err < 0)
+			goto end;
+	}
+
+	rcu_read_lock();
+	idr_for_each(&net_cb.tgt_net->netns_ids, rtnl_net_dumpid_one, &net_cb);
+	rcu_read_unlock();
+
+	cb->args[0] = net_cb.idx;
+end:
+	if (net_cb.fillargs.add_ref)
+		put_net(net_cb.tgt_net);
+	return err < 0 ? err : skb->len;
+}
+
+static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
+			      struct nlmsghdr *nlh, gfp_t gfp)
+{
+	struct net_fill_args fillargs = {
+		.portid = portid,
+		.seq = nlh ? nlh->nlmsg_seq : 0,
+		.cmd = cmd,
+		.nsid = id,
+	};
+	struct sk_buff *msg;
+	int err = -ENOMEM;
+
+	msg = nlmsg_new(rtnl_net_get_size(), gfp);
+	if (!msg)
+		goto out;
+
+	err = rtnl_net_fill(msg, &fillargs);
+	if (err < 0)
+		goto err_out;
+
+	rtnl_notify(msg, net, portid, RTNLGRP_NSID, nlh, gfp);
+	return;
+
+err_out:
+	nlmsg_free(msg);
+out:
+	rtnl_set_sk_err(net, RTNLGRP_NSID, err);
+}
+
+void __init net_ns_init(void)
+{
+	struct net_generic *ng;
+
+#ifdef CONFIG_NET_NS
+	net_cachep = kmem_cache_create("net_namespace", sizeof(struct net),
+					SMP_CACHE_BYTES,
+					SLAB_PANIC|SLAB_ACCOUNT, NULL);
+
+	/* Create workqueue for cleanup */
+	netns_wq = create_singlethread_workqueue("netns");
+	if (!netns_wq)
+		panic("Could not create netns workq");
+#endif
+
+	ng = net_alloc_generic();
+	if (!ng)
+		panic("Could not allocate generic netns");
+
+	rcu_assign_pointer(init_net.gen, ng);
+
+#ifdef CONFIG_KEYS
+	init_net.key_domain = &init_net_key_domain;
+#endif
+	down_write(&pernet_ops_rwsem);
+	preinit_net(&init_net);
+	if (setup_net(&init_net, &init_user_ns))
+		panic("Could not setup the initial network namespace");
+
+	init_net_initialized = true;
+	up_write(&pernet_ops_rwsem);
+
+	if (register_pernet_subsys(&net_ns_ops))
+		panic("Could not register network namespace subsystems");
+
+	rtnl_register(PF_UNSPEC, RTM_NEWNSID, rtnl_net_newid, NULL,
+		      RTNL_FLAG_DOIT_UNLOCKED);
+	rtnl_register(PF_UNSPEC, RTM_GETNSID, rtnl_net_getid, rtnl_net_dumpid,
+		      RTNL_FLAG_DOIT_UNLOCKED);
+}
+
+static void free_exit_list(struct pernet_operations *ops, struct list_head *net_exit_list)
+{
+	ops_pre_exit_list(ops, net_exit_list);
+	synchronize_rcu();
+	ops_exit_list(ops, net_exit_list);
+	ops_free_list(ops, net_exit_list);
+}
+
+#ifdef CONFIG_NET_NS
+static int __register_pernet_operations(struct list_head *list,
+					struct pernet_operations *ops)
+{
+	struct net *net;
+	int error;
+	LIST_HEAD(net_exit_list);
+
+	list_add_tail(&ops->list, list);
+	if (ops->init || (ops->id && ops->size)) {
+		/* We held write locked pernet_ops_rwsem, and parallel
+		 * setup_net() and cleanup_net() are not possible.
+		 */
+		for_each_net(net) {
+			error = ops_init(ops, net);
+			if (error)
+				goto out_undo;
+			list_add_tail(&net->exit_list, &net_exit_list);
+		}
+	}
+	return 0;
+
+out_undo:
+	/* If I have an error cleanup all namespaces I initialized */
+	list_del(&ops->list);
+	free_exit_list(ops, &net_exit_list);
+	return error;
+}
+
+static void __unregister_pernet_operations(struct pernet_operations *ops)
+{
+	struct net *net;
+	LIST_HEAD(net_exit_list);
+
+	list_del(&ops->list);
+	/* See comment in __register_pernet_operations() */
+	for_each_net(net)
+		list_add_tail(&net->exit_list, &net_exit_list);
+
+	free_exit_list(ops, &net_exit_list);
+}
+
+#else
+
+static int __register_pernet_operations(struct list_head *list,
+					struct pernet_operations *ops)
+{
+	if (!init_net_initialized) {
+		list_add_tail(&ops->list, list);
+		return 0;
+	}
+
+	return ops_init(ops, &init_net);
+}
+
+static void __unregister_pernet_operations(struct pernet_operations *ops)
+{
+	if (!init_net_initialized) {
+		list_del(&ops->list);
+	} else {
+		LIST_HEAD(net_exit_list);
+		list_add(&init_net.exit_list, &net_exit_list);
+		free_exit_list(ops, &net_exit_list);
+	}
+}
+
+#endif /* CONFIG_NET_NS */
+
+static DEFINE_IDA(net_generic_ids);
+
+static int register_pernet_operations(struct list_head *list,
+				      struct pernet_operations *ops)
+{
+	int error;
+
+	if (ops->id) {
+		error = ida_alloc_min(&net_generic_ids, MIN_PERNET_OPS_ID,
+				GFP_KERNEL);
+		if (error < 0)
+			return error;
+		*ops->id = error;
+		max_gen_ptrs = max(max_gen_ptrs, *ops->id + 1);
+	}
+	error = __register_pernet_operations(list, ops);
+	if (error) {
+		rcu_barrier();
+		if (ops->id)
+			ida_free(&net_generic_ids, *ops->id);
+	}
+
+	return error;
+}
+
+static void unregister_pernet_operations(struct pernet_operations *ops)
+{
+	__unregister_pernet_operations(ops);
+	rcu_barrier();
+	if (ops->id)
+		ida_free(&net_generic_ids, *ops->id);
+}
+
+/**
+ *      register_pernet_subsys - register a network namespace subsystem
+ *	@ops:  pernet operations structure for the subsystem
+ *
+ *	Register a subsystem which has init and exit functions
+ *	that are called when network namespaces are created and
+ *	destroyed respectively.
+ *
+ *	When registered all network namespace init functions are
+ *	called for every existing network namespace.  Allowing kernel
+ *	modules to have a race free view of the set of network namespaces.
+ *
+ *	When a new network namespace is created all of the init
+ *	methods are called in the order in which they were registered.
+ *
+ *	When a network namespace is destroyed all of the exit methods
+ *	are called in the reverse of the order with which they were
+ *	registered.
+ */
+int register_pernet_subsys(struct pernet_operations *ops)
+{
+	int error;
+	down_write(&pernet_ops_rwsem);
+	error =  register_pernet_operations(first_device, ops);
+	up_write(&pernet_ops_rwsem);
+	return error;
+}
+EXPORT_SYMBOL_GPL(register_pernet_subsys);
+
+/**
+ *      unregister_pernet_subsys - unregister a network namespace subsystem
+ *	@ops: pernet operations structure to manipulate
+ *
+ *	Remove the pernet operations structure from the list to be
+ *	used when network namespaces are created or destroyed.  In
+ *	addition run the exit method for all existing network
+ *	namespaces.
+ */
+void unregister_pernet_subsys(struct pernet_operations *ops)
+{
+	down_write(&pernet_ops_rwsem);
+	unregister_pernet_operations(ops);
+	up_write(&pernet_ops_rwsem);
+}
+EXPORT_SYMBOL_GPL(unregister_pernet_subsys);
+
+/**
+ *      register_pernet_device - register a network namespace device
+ *	@ops:  pernet operations structure for the subsystem
+ *
+ *	Register a device which has init and exit functions
+ *	that are called when network namespaces are created and
+ *	destroyed respectively.
+ *
+ *	When registered all network namespace init functions are
+ *	called for every existing network namespace.  Allowing kernel
+ *	modules to have a race free view of the set of network namespaces.
+ *
+ *	When a new network namespace is created all of the init
+ *	methods are called in the order in which they were registered.
+ *
+ *	When a network namespace is destroyed all of the exit methods
+ *	are called in the reverse of the order with which they were
+ *	registered.
+ */
+int register_pernet_device(struct pernet_operations *ops)
+{
+	int error;
+	down_write(&pernet_ops_rwsem);
+	error = register_pernet_operations(&pernet_list, ops);
+	if (!error && (first_device == &pernet_list))
+		first_device = &ops->list;
+	up_write(&pernet_ops_rwsem);
+	return error;
+}
+EXPORT_SYMBOL_GPL(register_pernet_device);
+
+/**
+ *      unregister_pernet_device - unregister a network namespace netdevice
+ *	@ops: pernet operations structure to manipulate
+ *
+ *	Remove the pernet operations structure from the list to be
+ *	used when network namespaces are created or destroyed.  In
+ *	addition run the exit method for all existing network
+ *	namespaces.
+ */
+void unregister_pernet_device(struct pernet_operations *ops)
+{
+	down_write(&pernet_ops_rwsem);
+	if (&ops->list == first_device)
+		first_device = first_device->next;
+	unregister_pernet_operations(ops);
+	up_write(&pernet_ops_rwsem);
+}
+EXPORT_SYMBOL_GPL(unregister_pernet_device);
+
+#ifdef CONFIG_NET_NS
+static struct ns_common *netns_get(struct task_struct *task)
+{
+	struct net *net = NULL;
+	struct nsproxy *nsproxy;
+
+	task_lock(task);
+	nsproxy = task->nsproxy;
+	if (nsproxy)
+		net = get_net(nsproxy->net_ns);
+	task_unlock(task);
+
+	return net ? &net->ns : NULL;
+}
+
+static inline struct net *to_net_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct net, ns);
+}
+
+static void netns_put(struct ns_common *ns)
+{
+	put_net(to_net_ns(ns));
+}
+
+static int netns_install(struct nsset *nsset, struct ns_common *ns)
+{
+	struct nsproxy *nsproxy = nsset->nsproxy;
+	struct net *net = to_net_ns(ns);
+
+	if (!ns_capable(net->user_ns, CAP_SYS_ADMIN) ||
+	    !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
+		return -EPERM;
+
+	put_net(nsproxy->net_ns);
+	nsproxy->net_ns = get_net(net);
+	return 0;
+}
+
+static struct user_namespace *netns_owner(struct ns_common *ns)
+{
+	return to_net_ns(ns)->user_ns;
+}
+
+const struct proc_ns_operations netns_operations = {
+	.name		= "net",
+	.type		= CLONE_NEWNET,
+	.get		= netns_get,
+	.put		= netns_put,
+	.install	= netns_install,
+	.owner		= netns_owner,
+};
+#endif