drivers/net/bareudp.c

// SPDX-License-Identifier: GPL-2.0
/* Bareudp: UDP  tunnel encasulation for different Payload types like
 * MPLS, NSH, IP, etc.
 * Copyright (c) 2019 Nokia, Inc.
 * Authors:  Martin Varghese, <martin.varghese@nokia.com>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/etherdevice.h>
#include <linux/hash.h>
#include <net/dst_metadata.h>
#include <net/gro_cells.h>
#include <net/rtnetlink.h>
#include <net/protocol.h>
#include <net/ip6_tunnel.h>
#include <net/ip_tunnels.h>
#include <net/udp_tunnel.h>
#include <net/bareudp.h>

#define BAREUDP_BASE_HLEN sizeof(struct udphdr)
#define BAREUDP_IPV4_HLEN (sizeof(struct iphdr) + \
			   sizeof(struct udphdr))
#define BAREUDP_IPV6_HLEN (sizeof(struct ipv6hdr) + \
			   sizeof(struct udphdr))

static bool log_ecn_error = true;
module_param(log_ecn_error, bool, 0644);
MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN");

/* per-network namespace private data for this module */

static unsigned int bareudp_net_id;

struct bareudp_net {
	struct list_head        bareudp_list;
};

/* Pseudo network device */
struct bareudp_dev {
	struct net         *net;        /* netns for packet i/o */
	struct net_device  *dev;        /* netdev for bareudp tunnel */
	__be16		   ethertype;
	__be16             port;
	u16	           sport_min;
	struct socket      __rcu *sock;
	struct list_head   next;        /* bareudp node  on namespace list */
	struct gro_cells   gro_cells;
};

static int bareudp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
{
	struct metadata_dst *tun_dst = NULL;
	struct pcpu_sw_netstats *stats;
	struct bareudp_dev *bareudp;
	unsigned short family;
	unsigned int len;
	__be16 proto;
	void *oiph;
	int err;

	bareudp = rcu_dereference_sk_user_data(sk);
	if (!bareudp)
		goto drop;

	if (skb->protocol ==  htons(ETH_P_IP))
		family = AF_INET;
	else
		family = AF_INET6;

	proto = bareudp->ethertype;

	if (iptunnel_pull_header(skb, BAREUDP_BASE_HLEN,
				 proto,
				 !net_eq(bareudp->net,
				 dev_net(bareudp->dev)))) {
		bareudp->dev->stats.rx_dropped++;
		goto drop;
	}

	tun_dst = udp_tun_rx_dst(skb, family, TUNNEL_KEY, 0, 0);
	if (!tun_dst) {
		bareudp->dev->stats.rx_dropped++;
		goto drop;
	}
	skb_dst_set(skb, &tun_dst->dst);
	skb->dev = bareudp->dev;
	oiph = skb_network_header(skb);
	skb_reset_network_header(skb);

	if (family == AF_INET)
		err = IP_ECN_decapsulate(oiph, skb);
#if IS_ENABLED(CONFIG_IPV6)
	else
		err = IP6_ECN_decapsulate(oiph, skb);
#endif

	if (unlikely(err)) {
		if (log_ecn_error) {
			if  (family == AF_INET)
				net_info_ratelimited("non-ECT from %pI4 "
						     "with TOS=%#x\n",
						     &((struct iphdr *)oiph)->saddr,
						     ((struct iphdr *)oiph)->tos);
#if IS_ENABLED(CONFIG_IPV6)
			else
				net_info_ratelimited("non-ECT from %pI6\n",
						     &((struct ipv6hdr *)oiph)->saddr);
#endif
		}
		if (err > 1) {
			++bareudp->dev->stats.rx_frame_errors;
			++bareudp->dev->stats.rx_errors;
			goto drop;
		}
	}

	len = skb->len;
	err = gro_cells_receive(&bareudp->gro_cells, skb);
	if (likely(err == NET_RX_SUCCESS)) {
		stats = this_cpu_ptr(bareudp->dev->tstats);
		u64_stats_update_begin(&stats->syncp);
		stats->rx_packets++;
		stats->rx_bytes += len;
		u64_stats_update_end(&stats->syncp);
	}
	return 0;
drop:
	/* Consume bad packet */
	kfree_skb(skb);

	return 0;
}

static int bareudp_err_lookup(struct sock *sk, struct sk_buff *skb)
{
	return 0;
}

static int bareudp_init(struct net_device *dev)
{
	struct bareudp_dev *bareudp = netdev_priv(dev);
	int err;

	dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
	if (!dev->tstats)
		return -ENOMEM;

	err = gro_cells_init(&bareudp->gro_cells, dev);
	if (err) {
		free_percpu(dev->tstats);
		return err;
	}
	return 0;
}

static void bareudp_uninit(struct net_device *dev)
{
	struct bareudp_dev *bareudp = netdev_priv(dev);

	gro_cells_destroy(&bareudp->gro_cells);
	free_percpu(dev->tstats);
}

static struct socket *bareudp_create_sock(struct net *net, __be16 port)
{
	struct udp_port_cfg udp_conf;
	struct socket *sock;
	int err;

	memset(&udp_conf, 0, sizeof(udp_conf));
#if IS_ENABLED(CONFIG_IPV6)
	udp_conf.family = AF_INET6;
#else
	udp_conf.family = AF_INET;
#endif
	udp_conf.local_udp_port = port;
	/* Open UDP socket */
	err = udp_sock_create(net, &udp_conf, &sock);
	if (err < 0)
		return ERR_PTR(err);

	return sock;
}

/* Create new listen socket if needed */
static int bareudp_socket_create(struct bareudp_dev *bareudp, __be16 port)
{
	struct udp_tunnel_sock_cfg tunnel_cfg;
	struct socket *sock;

	sock = bareudp_create_sock(bareudp->net, port);
	if (IS_ERR(sock))
		return PTR_ERR(sock);

	/* Mark socket as an encapsulation socket */
	memset(&tunnel_cfg, 0, sizeof(tunnel_cfg));
	tunnel_cfg.sk_user_data = bareudp;
	tunnel_cfg.encap_type = 1;
	tunnel_cfg.encap_rcv = bareudp_udp_encap_recv;
	tunnel_cfg.encap_err_lookup = bareudp_err_lookup;
	tunnel_cfg.encap_destroy = NULL;
	setup_udp_tunnel_sock(bareudp->net, sock, &tunnel_cfg);

	if (sock->sk->sk_family == AF_INET6)
		udp_encap_enable();

	rcu_assign_pointer(bareudp->sock, sock);
	return 0;
}

static int bareudp_open(struct net_device *dev)
{
	struct bareudp_dev *bareudp = netdev_priv(dev);
	int ret = 0;

	ret =  bareudp_socket_create(bareudp, bareudp->port);
	return ret;
}

static void bareudp_sock_release(struct bareudp_dev *bareudp)
{
	struct socket *sock;

	sock = bareudp->sock;
	rcu_assign_pointer(bareudp->sock, NULL);
	synchronize_net();
	udp_tunnel_sock_release(sock);
}

static int bareudp_stop(struct net_device *dev)
{
	struct bareudp_dev *bareudp = netdev_priv(dev);

	bareudp_sock_release(bareudp);
	return 0;
}

static int bareudp_xmit_skb(struct sk_buff *skb, struct net_device *dev,
			    struct bareudp_dev *bareudp,
			    const struct ip_tunnel_info *info)
{
	bool xnet = !net_eq(bareudp->net, dev_net(bareudp->dev));
	bool use_cache = ip_tunnel_dst_cache_usable(skb, info);
	struct socket *sock = rcu_dereference(bareudp->sock);
	bool udp_sum = !!(info->key.tun_flags & TUNNEL_CSUM);
	const struct ip_tunnel_key *key = &info->key;
	struct rtable *rt;
	__be16 sport, df;
	int min_headroom;
	__u8 tos, ttl;
	__be32 saddr;
	int err;

	if (!sock)
		return -ESHUTDOWN;

	rt = ip_route_output_tunnel(skb, dev, bareudp->net, &saddr, info,
				    IPPROTO_UDP, use_cache);

	if (IS_ERR(rt))
		return PTR_ERR(rt);

	skb_tunnel_check_pmtu(skb, &rt->dst,
			      BAREUDP_IPV4_HLEN + info->options_len);

	sport = udp_flow_src_port(bareudp->net, skb,
				  bareudp->sport_min, USHRT_MAX,
				  true);
	tos = ip_tunnel_ecn_encap(key->tos, ip_hdr(skb), skb);
	ttl = key->ttl;
	df = key->tun_flags & TUNNEL_DONT_FRAGMENT ? htons(IP_DF) : 0;
	skb_scrub_packet(skb, xnet);

	if (!skb_pull(skb, skb_network_offset(skb)))
		goto free_dst;

	min_headroom = LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len +
		BAREUDP_BASE_HLEN + info->options_len + sizeof(struct iphdr);

	err = skb_cow_head(skb, min_headroom);
	if (unlikely(err))
		goto free_dst;

	err = udp_tunnel_handle_offloads(skb, udp_sum);
	if (err)
		goto free_dst;

	skb_set_inner_protocol(skb, bareudp->ethertype);
	udp_tunnel_xmit_skb(rt, sock->sk, skb, saddr, info->key.u.ipv4.dst,
			    tos, ttl, df, sport, bareudp->port,
			    !net_eq(bareudp->net, dev_net(bareudp->dev)),
			    !(info->key.tun_flags & TUNNEL_CSUM));
	return 0;

free_dst:
	dst_release(&rt->dst);
	return err;
}

#if IS_ENABLED(CONFIG_IPV6)
static int bareudp6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
			     struct bareudp_dev *bareudp,
			     const struct ip_tunnel_info *info)
{
	bool xnet = !net_eq(bareudp->net, dev_net(bareudp->dev));
	bool use_cache = ip_tunnel_dst_cache_usable(skb, info);
	struct socket *sock  = rcu_dereference(bareudp->sock);
	bool udp_sum = !!(info->key.tun_flags & TUNNEL_CSUM);
	const struct ip_tunnel_key *key = &info->key;
	struct dst_entry *dst = NULL;
	struct in6_addr saddr, daddr;
	int min_headroom;
	__u8 prio, ttl;
	__be16 sport;
	int err;

	if (!sock)
		return -ESHUTDOWN;

	dst = ip6_dst_lookup_tunnel(skb, dev, bareudp->net, sock, &saddr, info,
				    IPPROTO_UDP, use_cache);
	if (IS_ERR(dst))
		return PTR_ERR(dst);

	skb_tunnel_check_pmtu(skb, dst, BAREUDP_IPV6_HLEN + info->options_len);

	sport = udp_flow_src_port(bareudp->net, skb,
				  bareudp->sport_min, USHRT_MAX,
				  true);
	prio = ip_tunnel_ecn_encap(key->tos, ip_hdr(skb), skb);
	ttl = key->ttl;

	skb_scrub_packet(skb, xnet);

	if (!skb_pull(skb, skb_network_offset(skb)))
		goto free_dst;

	min_headroom = LL_RESERVED_SPACE(dst->dev) + dst->header_len +
		BAREUDP_BASE_HLEN + info->options_len + sizeof(struct iphdr);

	err = skb_cow_head(skb, min_headroom);
	if (unlikely(err))
		goto free_dst;

	err = udp_tunnel_handle_offloads(skb, udp_sum);
	if (err)
		goto free_dst;

	daddr = info->key.u.ipv6.dst;
	udp_tunnel6_xmit_skb(dst, sock->sk, skb, dev,
			     &saddr, &daddr, prio, ttl,
			     info->key.label, sport, bareudp->port,
			     !(info->key.tun_flags & TUNNEL_CSUM));
	return 0;

free_dst:
	dst_release(dst);
	return err;
}
#endif

static netdev_tx_t bareudp_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct bareudp_dev *bareudp = netdev_priv(dev);
	struct ip_tunnel_info *info = NULL;
	int err;

	if (skb->protocol != bareudp->ethertype) {
		err = -EINVAL;
		goto tx_error;
	}

	info = skb_tunnel_info(skb);
	if (unlikely(!info || !(info->mode & IP_TUNNEL_INFO_TX))) {
		err = -EINVAL;
		goto tx_error;
	}

	rcu_read_lock();
#if IS_ENABLED(CONFIG_IPV6)
	if (info->mode & IP_TUNNEL_INFO_IPV6)
		err = bareudp6_xmit_skb(skb, dev, bareudp, info);
	else
#endif
		err = bareudp_xmit_skb(skb, dev, bareudp, info);

	rcu_read_unlock();

	if (likely(!err))
		return NETDEV_TX_OK;
tx_error:
	dev_kfree_skb(skb);

	if (err == -ELOOP)
		dev->stats.collisions++;
	else if (err == -ENETUNREACH)
		dev->stats.tx_carrier_errors++;

	dev->stats.tx_errors++;
	return NETDEV_TX_OK;
}

static int bareudp_fill_metadata_dst(struct net_device *dev,
				     struct sk_buff *skb)
{
	struct ip_tunnel_info *info = skb_tunnel_info(skb);
	struct bareudp_dev *bareudp = netdev_priv(dev);
	bool use_cache;

	use_cache = ip_tunnel_dst_cache_usable(skb, info);

	if (ip_tunnel_info_af(info) == AF_INET) {
		struct rtable *rt;
		__be32 saddr;

		rt = ip_route_output_tunnel(skb, dev, bareudp->net, &saddr,
					    info, IPPROTO_UDP, use_cache);
		if (IS_ERR(rt))
			return PTR_ERR(rt);

		ip_rt_put(rt);
		info->key.u.ipv4.src = saddr;
#if IS_ENABLED(CONFIG_IPV6)
	} else if (ip_tunnel_info_af(info) == AF_INET6) {
		struct dst_entry *dst;
		struct in6_addr saddr;
		struct socket *sock = rcu_dereference(bareudp->sock);

		dst = ip6_dst_lookup_tunnel(skb, dev, bareudp->net, sock,
					    &saddr, info, IPPROTO_UDP,
					    use_cache);
		if (IS_ERR(dst))
			return PTR_ERR(dst);

		dst_release(dst);
		info->key.u.ipv6.src = saddr;
#endif
	} else {
		return -EINVAL;
	}

	info->key.tp_src = udp_flow_src_port(bareudp->net, skb,
					     bareudp->sport_min,
			USHRT_MAX, true);
	info->key.tp_dst = bareudp->port;
	return 0;
}

static const struct net_device_ops bareudp_netdev_ops = {
	.ndo_init               = bareudp_init,
	.ndo_uninit             = bareudp_uninit,
	.ndo_open               = bareudp_open,
	.ndo_stop               = bareudp_stop,
	.ndo_start_xmit         = bareudp_xmit,
	.ndo_get_stats64        = ip_tunnel_get_stats64,
	.ndo_fill_metadata_dst  = bareudp_fill_metadata_dst,
};

static const struct nla_policy bareudp_policy[IFLA_BAREUDP_MAX + 1] = {
	[IFLA_BAREUDP_PORT]                = { .type = NLA_U16 },
	[IFLA_BAREUDP_ETHERTYPE]	   = { .type = NLA_U16 },
	[IFLA_BAREUDP_SRCPORT_MIN]         = { .type = NLA_U16 },
};

/* Info for udev, that this is a virtual tunnel endpoint */
static struct device_type bareudp_type = {
	.name = "bareudp",
};

/* Initialize the device structure. */
static void bareudp_setup(struct net_device *dev)
{
	dev->netdev_ops = &bareudp_netdev_ops;
	dev->needs_free_netdev = true;
	SET_NETDEV_DEVTYPE(dev, &bareudp_type);
	dev->features    |= NETIF_F_SG | NETIF_F_HW_CSUM;
	dev->features    |= NETIF_F_RXCSUM;
	dev->features    |= NETIF_F_GSO_SOFTWARE;
	dev->hw_features |= NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_RXCSUM;
	dev->hw_features |= NETIF_F_GSO_SOFTWARE;
	dev->hard_header_len = 0;
	dev->addr_len = 0;
	dev->mtu = ETH_DATA_LEN;
	dev->min_mtu = IPV4_MIN_MTU;
	dev->max_mtu = IP_MAX_MTU - BAREUDP_BASE_HLEN;
	dev->type = ARPHRD_NONE;
	netif_keep_dst(dev);
	dev->priv_flags |= IFF_NO_QUEUE;
	dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
}

static int bareudp_validate(struct nlattr *tb[], struct nlattr *data[],
			    struct netlink_ext_ack *extack)
{
	if (!data) {
		NL_SET_ERR_MSG(extack,
			       "Not enough attributes provided to perform the operation");
		return -EINVAL;
	}
	return 0;
}

static int bareudp2info(struct nlattr *data[], struct bareudp_conf *conf)
{
	if (!data[IFLA_BAREUDP_PORT] || !data[IFLA_BAREUDP_ETHERTYPE])
		return -EINVAL;

	if (data[IFLA_BAREUDP_PORT])
		conf->port =  nla_get_u16(data[IFLA_BAREUDP_PORT]);

	if (data[IFLA_BAREUDP_ETHERTYPE])
		conf->ethertype =  nla_get_u16(data[IFLA_BAREUDP_ETHERTYPE]);

	if (data[IFLA_BAREUDP_SRCPORT_MIN])
		conf->sport_min =  nla_get_u16(data[IFLA_BAREUDP_SRCPORT_MIN]);

	return 0;
}

static struct bareudp_dev *bareudp_find_dev(struct bareudp_net *bn,
					    const struct bareudp_conf *conf)
{
	struct bareudp_dev *bareudp, *t = NULL;

	list_for_each_entry(bareudp, &bn->bareudp_list, next) {
		if (conf->port == bareudp->port)
			t = bareudp;
	}
	return t;
}

static int bareudp_configure(struct net *net, struct net_device *dev,
			     struct bareudp_conf *conf)
{
	struct bareudp_net *bn = net_generic(net, bareudp_net_id);
	struct bareudp_dev *t, *bareudp = netdev_priv(dev);
	int err;

	bareudp->net = net;
	bareudp->dev = dev;
	t = bareudp_find_dev(bn, conf);
	if (t)
		return -EBUSY;

	bareudp->port = conf->port;
	bareudp->ethertype = conf->ethertype;
	bareudp->sport_min = conf->sport_min;
	err = register_netdevice(dev);
	if (err)
		return err;

	list_add(&bareudp->next, &bn->bareudp_list);
	return 0;
}

static int bareudp_link_config(struct net_device *dev,
			       struct nlattr *tb[])
{
	int err;

	if (tb[IFLA_MTU]) {
		err = dev_set_mtu(dev, nla_get_u32(tb[IFLA_MTU]));
		if (err)
			return err;
	}
	return 0;
}

static int bareudp_newlink(struct net *net, struct net_device *dev,
			   struct nlattr *tb[], struct nlattr *data[],
			   struct netlink_ext_ack *extack)
{
	struct bareudp_conf conf;
	int err;

	err = bareudp2info(data, &conf);
	if (err)
		return err;

	err = bareudp_configure(net, dev, &conf);
	if (err)
		return err;

	err = bareudp_link_config(dev, tb);
	if (err)
		return err;

	return 0;
}

static void bareudp_dellink(struct net_device *dev, struct list_head *head)
{
	struct bareudp_dev *bareudp = netdev_priv(dev);

	list_del(&bareudp->next);
	unregister_netdevice_queue(dev, head);
}

static size_t bareudp_get_size(const struct net_device *dev)
{
	return  nla_total_size(sizeof(__be16)) +  /* IFLA_BAREUDP_PORT */
		nla_total_size(sizeof(__be16)) +  /* IFLA_BAREUDP_ETHERTYPE */
		nla_total_size(sizeof(__u16))  +  /* IFLA_BAREUDP_SRCPORT_MIN */
		0;
}

static int bareudp_fill_info(struct sk_buff *skb, const struct net_device *dev)
{
	struct bareudp_dev *bareudp = netdev_priv(dev);

	if (nla_put_be16(skb, IFLA_BAREUDP_PORT, bareudp->port))
		goto nla_put_failure;
	if (nla_put_be16(skb, IFLA_BAREUDP_ETHERTYPE, bareudp->ethertype))
		goto nla_put_failure;
	if (nla_put_u16(skb, IFLA_BAREUDP_SRCPORT_MIN, bareudp->sport_min))
		goto nla_put_failure;

	return 0;

nla_put_failure:
	return -EMSGSIZE;
}

static struct rtnl_link_ops bareudp_link_ops __read_mostly = {
	.kind           = "bareudp",
	.maxtype        = IFLA_BAREUDP_MAX,
	.policy         = bareudp_policy,
	.priv_size      = sizeof(struct bareudp_dev),
	.setup          = bareudp_setup,
	.validate       = bareudp_validate,
	.newlink        = bareudp_newlink,
	.dellink        = bareudp_dellink,
	.get_size       = bareudp_get_size,
	.fill_info      = bareudp_fill_info,
};

struct net_device *bareudp_dev_create(struct net *net, const char *name,
				      u8 name_assign_type,
				      struct bareudp_conf *conf)
{
	struct nlattr *tb[IFLA_MAX + 1];
	struct net_device *dev;
	LIST_HEAD(list_kill);
	int err;

	memset(tb, 0, sizeof(tb));
	dev = rtnl_create_link(net, name, name_assign_type,
			       &bareudp_link_ops, tb, NULL);
	if (IS_ERR(dev))
		return dev;

	err = bareudp_configure(net, dev, conf);
	if (err) {
		free_netdev(dev);
		return ERR_PTR(err);
	}
	err = dev_set_mtu(dev, IP_MAX_MTU - BAREUDP_BASE_HLEN);
	if (err)
		goto err;

	err = rtnl_configure_link(dev, NULL);
	if (err < 0)
		goto err;

	return dev;
err:
	bareudp_dellink(dev, &list_kill);
	unregister_netdevice_many(&list_kill);
	return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(bareudp_dev_create);

static __net_init int bareudp_init_net(struct net *net)
{
	struct bareudp_net *bn = net_generic(net, bareudp_net_id);

	INIT_LIST_HEAD(&bn->bareudp_list);
	return 0;
}

static void bareudp_destroy_tunnels(struct net *net, struct list_head *head)
{
	struct bareudp_net *bn = net_generic(net, bareudp_net_id);
	struct bareudp_dev *bareudp, *next;

	list_for_each_entry_safe(bareudp, next, &bn->bareudp_list, next)
		unregister_netdevice_queue(bareudp->dev, head);
}

static void __net_exit bareudp_exit_batch_net(struct list_head *net_list)
{
	struct net *net;
	LIST_HEAD(list);

	rtnl_lock();
	list_for_each_entry(net, net_list, exit_list)
		bareudp_destroy_tunnels(net, &list);

	/* unregister the devices gathered above */
	unregister_netdevice_many(&list);
	rtnl_unlock();
}

static struct pernet_operations bareudp_net_ops = {
	.init = bareudp_init_net,
	.exit_batch = bareudp_exit_batch_net,
	.id   = &bareudp_net_id,
	.size = sizeof(struct bareudp_net),
};

static int __init bareudp_init_module(void)
{
	int rc;

	rc = register_pernet_subsys(&bareudp_net_ops);
	if (rc)
		goto out1;

	rc = rtnl_link_register(&bareudp_link_ops);
	if (rc)
		goto out2;

	return 0;
out2:
	unregister_pernet_subsys(&bareudp_net_ops);
out1:
	return rc;
}
late_initcall(bareudp_init_module);

static void __exit bareudp_cleanup_module(void)
{
	rtnl_link_unregister(&bareudp_link_ops);
	unregister_pernet_subsys(&bareudp_net_ops);
}
module_exit(bareudp_cleanup_module);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Martin Varghese <martin.varghese@nokia.com>");
MODULE_DESCRIPTION("Interface driver for UDP encapsulated traffic");