kernel / drivers / net / wireguard / netlink.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2015-2019 Jason A. Donenfeld <[e-mail]>. All Rights Reserved.
 */

#include "netlink.h"
#include "device.h"
#include "peer.h"
#include "socket.h"
#include "queueing.h"
#include "messages.h"
#include "generated/netlink.h"

#include <uapi/linux/wireguard.h>

#include <linux/if.h>
#include <net/genetlink.h>
#include <net/sock.h>
#include <crypto/utils.h>

static struct genl_family genl_family;

static struct wg_device *lookup_interface(struct nlattr **attrs,
					  struct sk_buff *skb)
{
	struct net_device *dev = NULL;

	if (!attrs[WGDEVICE_A_IFINDEX] == !attrs[WGDEVICE_A_IFNAME])
		return ERR_PTR(-EBADR);
	if (attrs[WGDEVICE_A_IFINDEX])
		dev = dev_get_by_index(sock_net(skb->sk),
				       nla_get_u32(attrs[WGDEVICE_A_IFINDEX]));
	else if (attrs[WGDEVICE_A_IFNAME])
		dev = dev_get_by_name(sock_net(skb->sk),
				      nla_data(attrs[WGDEVICE_A_IFNAME]));
	if (!dev)
		return ERR_PTR(-ENODEV);
	if (!dev->rtnl_link_ops || !dev->rtnl_link_ops->kind ||
	    strcmp(dev->rtnl_link_ops->kind, KBUILD_MODNAME)) {
		dev_put(dev);
		return ERR_PTR(-EOPNOTSUPP);
	}
	return netdev_priv(dev);
}

static int get_allowedips(struct sk_buff *skb, const u8 *ip, u8 cidr,
			  int family)
{
	struct nlattr *allowedip_nest;

	allowedip_nest = nla_nest_start(skb, 0);
	if (!allowedip_nest)
		return -EMSGSIZE;

	if (nla_put_u8(skb, WGALLOWEDIP_A_CIDR_MASK, cidr) ||
	    nla_put_u16(skb, WGALLOWEDIP_A_FAMILY, family) ||
	    nla_put(skb, WGALLOWEDIP_A_IPADDR, family == AF_INET6 ?
		    sizeof(struct in6_addr) : sizeof(struct in_addr), ip)) {
		nla_nest_cancel(skb, allowedip_nest);
		return -EMSGSIZE;
	}

	nla_nest_end(skb, allowedip_nest);
	return 0;
}

struct dump_ctx {
	struct wg_device *wg;
	struct wg_peer *next_peer;
	u64 allowedips_seq;
	struct allowedips_node *next_allowedip;
};

#define DUMP_CTX(cb) ((struct dump_ctx *)(cb)->args)

static int
get_peer(struct wg_peer *peer, struct sk_buff *skb, struct dump_ctx *ctx)
{

	struct nlattr *allowedips_nest, *peer_nest = nla_nest_start(skb, 0);
	struct allowedips_node *allowedips_node = ctx->next_allowedip;
	bool fail;

	if (!peer_nest)
		return -EMSGSIZE;

	down_read(&peer->handshake.lock);
	fail = nla_put(skb, WGPEER_A_PUBLIC_KEY, NOISE_PUBLIC_KEY_LEN,
		       peer->handshake.remote_static);
	up_read(&peer->handshake.lock);
	if (fail)
		goto err;

	if (!allowedips_node) {
		const struct __kernel_timespec last_handshake = {
			.tv_sec = peer->walltime_last_handshake.tv_sec,
			.tv_nsec = peer->walltime_last_handshake.tv_nsec
		};

		down_read(&peer->handshake.lock);
		fail = nla_put(skb, WGPEER_A_PRESHARED_KEY,
			       NOISE_SYMMETRIC_KEY_LEN,
			       peer->handshake.preshared_key);
		up_read(&peer->handshake.lock);
		if (fail)
			goto err;

		if (nla_put(skb, WGPEER_A_LAST_HANDSHAKE_TIME,
			    sizeof(last_handshake), &last_handshake) ||
		    nla_put_u16(skb, WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL,
				peer->persistent_keepalive_interval) ||
		    nla_put_u64_64bit(skb, WGPEER_A_TX_BYTES, peer->tx_bytes,
				      WGPEER_A_UNSPEC) ||
		    nla_put_u64_64bit(skb, WGPEER_A_RX_BYTES, peer->rx_bytes,
				      WGPEER_A_UNSPEC) ||
		    nla_put_u32(skb, WGPEER_A_PROTOCOL_VERSION, 1))
			goto err;

		read_lock_bh(&peer->endpoint_lock);
		if (peer->endpoint.addr.sa_family == AF_INET)
			fail = nla_put(skb, WGPEER_A_ENDPOINT,
				       sizeof(peer->endpoint.addr4),
				       &peer->endpoint.addr4);
		else if (peer->endpoint.addr.sa_family == AF_INET6)
			fail = nla_put(skb, WGPEER_A_ENDPOINT,
				       sizeof(peer->endpoint.addr6),
				       &peer->endpoint.addr6);
		read_unlock_bh(&peer->endpoint_lock);
		if (fail)
			goto err;
		allowedips_node =
			list_first_entry_or_null(&peer->allowedips_list,
					struct allowedips_node, peer_list);
	}
	if (!allowedips_node)
		goto no_allowedips;
	if (!ctx->allowedips_seq)
		ctx->allowedips_seq = ctx->wg->peer_allowedips.seq;
	else if (ctx->allowedips_seq != ctx->wg->peer_allowedips.seq)
		goto no_allowedips;

	allowedips_nest = nla_nest_start(skb, WGPEER_A_ALLOWEDIPS);
	if (!allowedips_nest)
		goto err;

	list_for_each_entry_from(allowedips_node, &peer->allowedips_list,
				 peer_list) {
		u8 cidr, ip[16] __aligned(__alignof(u64));
		int family;

		family = wg_allowedips_read_node(allowedips_node, ip, &cidr);
		if (get_allowedips(skb, ip, cidr, family)) {
			nla_nest_end(skb, allowedips_nest);
			nla_nest_end(skb, peer_nest);
			ctx->next_allowedip = allowedips_node;
			return -EMSGSIZE;
		}
	}
	nla_nest_end(skb, allowedips_nest);
no_allowedips:
	nla_nest_end(skb, peer_nest);
	ctx->next_allowedip = NULL;
	ctx->allowedips_seq = 0;
	return 0;
err:
	nla_nest_cancel(skb, peer_nest);
	return -EMSGSIZE;
}

int wg_get_device_start(struct netlink_callback *cb)
{
	struct wg_device *wg;

	wg = lookup_interface(genl_info_dump(cb)->attrs, cb->skb);
	if (IS_ERR(wg))
		return PTR_ERR(wg);
	DUMP_CTX(cb)->wg = wg;
	return 0;
}

int wg_get_device_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
{
	struct wg_peer *peer, *next_peer_cursor;
	struct dump_ctx *ctx = DUMP_CTX(cb);
	struct wg_device *wg = ctx->wg;
	struct nlattr *peers_nest;
	int ret = -EMSGSIZE;
	bool done = true;
	void *hdr;

	rtnl_lock();
	mutex_lock(&wg->device_update_lock);
	cb->seq = wg->device_update_gen;
	next_peer_cursor = ctx->next_peer;

	hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
			  &genl_family, NLM_F_MULTI, WG_CMD_GET_DEVICE);
	if (!hdr)
		goto out;
	genl_dump_check_consistent(cb, hdr);

	if (!ctx->next_peer) {
		if (nla_put_u16(skb, WGDEVICE_A_LISTEN_PORT,
				wg->incoming_port) ||
		    nla_put_u32(skb, WGDEVICE_A_FWMARK, wg->fwmark) ||
		    nla_put_u32(skb, WGDEVICE_A_IFINDEX, wg->dev->ifindex) ||
		    nla_put_string(skb, WGDEVICE_A_IFNAME, wg->dev->name))
			goto out;

		down_read(&wg->static_identity.lock);
		if (wg->static_identity.has_identity) {
			if (nla_put(skb, WGDEVICE_A_PRIVATE_KEY,
				    NOISE_PUBLIC_KEY_LEN,
				    wg->static_identity.static_private) ||
			    nla_put(skb, WGDEVICE_A_PUBLIC_KEY,
				    NOISE_PUBLIC_KEY_LEN,
				    wg->static_identity.static_public)) {
				up_read(&wg->static_identity.lock);
				goto out;
			}
		}
		up_read(&wg->static_identity.lock);
	}

	peers_nest = nla_nest_start(skb, WGDEVICE_A_PEERS);
	if (!peers_nest)
		goto out;
	ret = 0;
	lockdep_assert_held(&wg->device_update_lock);
	/* If the last cursor was removed in peer_remove or peer_remove_all, then
	 * we just treat this the same as there being no more peers left. The
	 * reason is that seq_nr should indicate to userspace that this isn't a
	 * coherent dump anyway, so they'll try again.
	 */
	if (list_empty(&wg->peer_list) ||
	    (ctx->next_peer && ctx->next_peer->is_dead)) {
		nla_nest_cancel(skb, peers_nest);
		goto out;
	}
	peer = list_prepare_entry(ctx->next_peer, &wg->peer_list, peer_list);
	list_for_each_entry_continue(peer, &wg->peer_list, peer_list) {
		if (get_peer(peer, skb, ctx)) {
			done = false;
			break;
		}
		next_peer_cursor = peer;
	}
	nla_nest_end(skb, peers_nest);

out:
	if (!ret && !done && next_peer_cursor)
		wg_peer_get(next_peer_cursor);
	wg_peer_put(ctx->next_peer);
	mutex_unlock(&wg->device_update_lock);
	rtnl_unlock();

	if (ret) {
		genlmsg_cancel(skb, hdr);
		return ret;
	}
	genlmsg_end(skb, hdr);
	if (done) {
		ctx->next_peer = NULL;
		return 0;
	}
	ctx->next_peer = next_peer_cursor;
	return skb->len;

	/* At this point, we can't really deal ourselves with safely zeroing out
	 * the private key material after usage. This will need an additional API
	 * in the kernel for marking skbs as zero_on_free.
	 */
}

int wg_get_device_done(struct netlink_callback *cb)
{
	struct dump_ctx *ctx = DUMP_CTX(cb);

	if (ctx->wg)
		dev_put(ctx->wg->dev);
	wg_peer_put(ctx->next_peer);
	return 0;
}

static int set_port(struct wg_device *wg, u16 port)
{
	struct wg_peer *peer;

	if (wg->incoming_port == port)
		return 0;
	list_for_each_entry(peer, &wg->peer_list, peer_list)
		wg_socket_clear_peer_endpoint_src(peer);
	if (!netif_running(wg->dev)) {
		wg->incoming_port = port;
		return 0;
	}
	return wg_socket_init(wg, port);
}

static int set_allowedip(struct wg_peer *peer, struct nlattr **attrs)
{
	int ret = -EINVAL;
	u32 flags = 0;
	u16 family;
	u8 cidr;

	if (!attrs[WGALLOWEDIP_A_FAMILY] || !attrs[WGALLOWEDIP_A_IPADDR] ||
	    !attrs[WGALLOWEDIP_A_CIDR_MASK])
		return ret;
	family = nla_get_u16(attrs[WGALLOWEDIP_A_FAMILY]);
	cidr = nla_get_u8(attrs[WGALLOWEDIP_A_CIDR_MASK]);
	if (attrs[WGALLOWEDIP_A_FLAGS])
		flags = nla_get_u32(attrs[WGALLOWEDIP_A_FLAGS]);

	if (family == AF_INET && cidr <= 32 &&
	    nla_len(attrs[WGALLOWEDIP_A_IPADDR]) == sizeof(struct in_addr)) {
		if (flags & WGALLOWEDIP_F_REMOVE_ME)
			ret = wg_allowedips_remove_v4(&peer->device->peer_allowedips,
						      nla_data(attrs[WGALLOWEDIP_A_IPADDR]), cidr,
						      peer, &peer->device->device_update_lock);
		else
			ret = wg_allowedips_insert_v4(&peer->device->peer_allowedips,
						      nla_data(attrs[WGALLOWEDIP_A_IPADDR]), cidr,
						      peer, &peer->device->device_update_lock);
	} else if (family == AF_INET6 && cidr <= 128 &&
		   nla_len(attrs[WGALLOWEDIP_A_IPADDR]) == sizeof(struct in6_addr)) {
		if (flags & WGALLOWEDIP_F_REMOVE_ME)
			ret = wg_allowedips_remove_v6(&peer->device->peer_allowedips,
						      nla_data(attrs[WGALLOWEDIP_A_IPADDR]), cidr,
						      peer, &peer->device->device_update_lock);
		else
			ret = wg_allowedips_insert_v6(&peer->device->peer_allowedips,
						      nla_data(attrs[WGALLOWEDIP_A_IPADDR]), cidr,
						      peer, &peer->device->device_update_lock);
	}

	return ret;
}

static int set_peer(struct wg_device *wg, struct nlattr **attrs)
{
	u8 *public_key = NULL, *preshared_key = NULL;
	struct wg_peer *peer = NULL;
	u32 flags = 0;
	int ret;

	ret = -EINVAL;
	if (attrs[WGPEER_A_PUBLIC_KEY] &&
	    nla_len(attrs[WGPEER_A_PUBLIC_KEY]) == NOISE_PUBLIC_KEY_LEN)
		public_key = nla_data(attrs[WGPEER_A_PUBLIC_KEY]);
	else
		goto out;
	if (attrs[WGPEER_A_PRESHARED_KEY] &&
	    nla_len(attrs[WGPEER_A_PRESHARED_KEY]) == NOISE_SYMMETRIC_KEY_LEN)
		preshared_key = nla_data(attrs[WGPEER_A_PRESHARED_KEY]);

	if (attrs[WGPEER_A_FLAGS])
		flags = nla_get_u32(attrs[WGPEER_A_FLAGS]);

	ret = -EPFNOSUPPORT;
	if (attrs[WGPEER_A_PROTOCOL_VERSION]) {
		if (nla_get_u32(attrs[WGPEER_A_PROTOCOL_VERSION]) != 1)
			goto out;
	}

	peer = wg_pubkey_hashtable_lookup(wg->peer_hashtable,
					  nla_data(attrs[WGPEER_A_PUBLIC_KEY]));
	ret = 0;
	if (!peer) { /* Peer doesn't exist yet. Add a new one. */
		if (flags & (WGPEER_F_REMOVE_ME | WGPEER_F_UPDATE_ONLY))
			goto out;

		/* The peer is new, so there aren't allowed IPs to remove. */
		flags &= ~WGPEER_F_REPLACE_ALLOWEDIPS;

		down_read(&wg->static_identity.lock);
		if (wg->static_identity.has_identity &&
		    !memcmp(nla_data(attrs[WGPEER_A_PUBLIC_KEY]),
			    wg->static_identity.static_public,
			    NOISE_PUBLIC_KEY_LEN)) {
			/* We silently ignore peers that have the same public
			 * key as the device. The reason we do it silently is
			 * that we'd like for people to be able to reuse the
			 * same set of API calls across peers.
			 */
			up_read(&wg->static_identity.lock);
			ret = 0;
			goto out;
		}
		up_read(&wg->static_identity.lock);

		peer = wg_peer_create(wg, public_key, preshared_key);
		if (IS_ERR(peer)) {
			ret = PTR_ERR(peer);
			peer = NULL;
			goto out;
		}
		/* Take additional reference, as though we've just been
		 * looked up.
		 */
		wg_peer_get(peer);
	}

	if (flags & WGPEER_F_REMOVE_ME) {
		wg_peer_remove(peer);
		goto out;
	}

	if (preshared_key) {
		down_write(&peer->handshake.lock);
		memcpy(&peer->handshake.preshared_key, preshared_key,
		       NOISE_SYMMETRIC_KEY_LEN);
		up_write(&peer->handshake.lock);
	}

	if (attrs[WGPEER_A_ENDPOINT]) {
		struct sockaddr *addr = nla_data(attrs[WGPEER_A_ENDPOINT]);
		size_t len = nla_len(attrs[WGPEER_A_ENDPOINT]);
		struct endpoint endpoint = { { { 0 } } };

		if (len == sizeof(struct sockaddr_in) && addr->sa_family == AF_INET) {
			endpoint.addr4 = *(struct sockaddr_in *)addr;
			wg_socket_set_peer_endpoint(peer, &endpoint);
		} else if (len == sizeof(struct sockaddr_in6) && addr->sa_family == AF_INET6) {
			endpoint.addr6 = *(struct sockaddr_in6 *)addr;
			wg_socket_set_peer_endpoint(peer, &endpoint);
		}
	}

	if (flags & WGPEER_F_REPLACE_ALLOWEDIPS)
		wg_allowedips_remove_by_peer(&wg->peer_allowedips, peer,
					     &wg->device_update_lock);

	if (attrs[WGPEER_A_ALLOWEDIPS]) {
		struct nlattr *attr, *allowedip[WGALLOWEDIP_A_MAX + 1];
		int rem;

		nla_for_each_nested(attr, attrs[WGPEER_A_ALLOWEDIPS], rem) {
			ret = nla_parse_nested(allowedip, WGALLOWEDIP_A_MAX,
					       attr, NULL, NULL);
			if (ret < 0)
				goto out;
			ret = set_allowedip(peer, allowedip);
			if (ret < 0)
				goto out;
		}
	}

	if (attrs[WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL]) {
		const u16 persistent_keepalive_interval = nla_get_u16(
				attrs[WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL]);
		const bool send_keepalive =
			!peer->persistent_keepalive_interval &&
			persistent_keepalive_interval &&
			netif_running(wg->dev);

		peer->persistent_keepalive_interval = persistent_keepalive_interval;
		if (send_keepalive)
			wg_packet_send_keepalive(peer);
	}

	if (netif_running(wg->dev))
		wg_packet_send_staged_packets(peer);

out:
	wg_peer_put(peer);
	if (attrs[WGPEER_A_PRESHARED_KEY])
		memzero_explicit(nla_data(attrs[WGPEER_A_PRESHARED_KEY]),
				 nla_len(attrs[WGPEER_A_PRESHARED_KEY]));
	return ret;
}

int wg_set_device_doit(struct sk_buff *skb, struct genl_info *info)
{
	struct wg_device *wg = lookup_interface(info->attrs, skb);
	u32 flags = 0;
	int ret;

	if (IS_ERR(wg)) {
		ret = PTR_ERR(wg);
		goto out_nodev;
	}

	rtnl_lock();
	mutex_lock(&wg->device_update_lock);

	if (info->attrs[WGDEVICE_A_FLAGS])
		flags = nla_get_u32(info->attrs[WGDEVICE_A_FLAGS]);

	if (info->attrs[WGDEVICE_A_LISTEN_PORT] || info->attrs[WGDEVICE_A_FWMARK]) {
		struct net *net;
		rcu_read_lock();
		net = rcu_dereference(wg->creating_net);
		ret = !net || !ns_capable(net->user_ns, CAP_NET_ADMIN) ? -EPERM : 0;
		rcu_read_unlock();
		if (ret)
			goto out;
	}

	++wg->device_update_gen;

	if (info->attrs[WGDEVICE_A_FWMARK]) {
		struct wg_peer *peer;

		wg->fwmark = nla_get_u32(info->attrs[WGDEVICE_A_FWMARK]);
		list_for_each_entry(peer, &wg->peer_list, peer_list)
			wg_socket_clear_peer_endpoint_src(peer);
	}

	if (info->attrs[WGDEVICE_A_LISTEN_PORT]) {
		ret = set_port(wg,
			nla_get_u16(info->attrs[WGDEVICE_A_LISTEN_PORT]));
		if (ret)
			goto out;
	}

	if (flags & WGDEVICE_F_REPLACE_PEERS)
		wg_peer_remove_all(wg);

	if (info->attrs[WGDEVICE_A_PRIVATE_KEY] &&
	    nla_len(info->attrs[WGDEVICE_A_PRIVATE_KEY]) ==
		    NOISE_PUBLIC_KEY_LEN) {
		u8 *private_key = nla_data(info->attrs[WGDEVICE_A_PRIVATE_KEY]);
		u8 public_key[NOISE_PUBLIC_KEY_LEN];
		struct wg_peer *peer, *temp;
		bool send_staged_packets;

		if (!crypto_memneq(wg->static_identity.static_private,
				   private_key, NOISE_PUBLIC_KEY_LEN))
			goto skip_set_private_key;

		/* We remove before setting, to prevent race, which means doing
		 * two 25519-genpub ops.
		 */
		if (curve25519_generate_public(public_key, private_key)) {
			peer = wg_pubkey_hashtable_lookup(wg->peer_hashtable,
							  public_key);
			if (peer) {
				wg_peer_put(peer);
				wg_peer_remove(peer);
			}
		}

		down_write(&wg->static_identity.lock);
		send_staged_packets = !wg->static_identity.has_identity && netif_running(wg->dev);
		wg_noise_set_static_identity_private_key(&wg->static_identity, private_key);
		send_staged_packets = send_staged_packets && wg->static_identity.has_identity;

		wg_cookie_checker_precompute_device_keys(&wg->cookie_checker);
		list_for_each_entry_safe(peer, temp, &wg->peer_list, peer_list) {
			wg_noise_precompute_static_static(peer);
			wg_noise_expire_current_peer_keypairs(peer);
			if (send_staged_packets)
				wg_packet_send_staged_packets(peer);
		}
		up_write(&wg->static_identity.lock);
	}
skip_set_private_key:

	if (info->attrs[WGDEVICE_A_PEERS]) {
		struct nlattr *attr, *peer[WGPEER_A_MAX + 1];
		int rem;

		nla_for_each_nested(attr, info->attrs[WGDEVICE_A_PEERS], rem) {
			ret = nla_parse_nested(peer, WGPEER_A_MAX, attr,
					       NULL, NULL);
			if (ret < 0)
				goto out;
			ret = set_peer(wg, peer);
			if (ret < 0)
				goto out;
		}
	}
	ret = 0;

out:
	mutex_unlock(&wg->device_update_lock);
	rtnl_unlock();
	dev_put(wg->dev);
out_nodev:
	if (info->attrs[WGDEVICE_A_PRIVATE_KEY])
		memzero_explicit(nla_data(info->attrs[WGDEVICE_A_PRIVATE_KEY]),
				 nla_len(info->attrs[WGDEVICE_A_PRIVATE_KEY]));
	return ret;
}

static struct genl_family genl_family __ro_after_init = {
	.split_ops = wireguard_nl_ops,
	.n_split_ops = ARRAY_SIZE(wireguard_nl_ops),
	.name = WG_GENL_NAME,
	.version = WG_GENL_VERSION,
	.module = THIS_MODULE,
	.netnsok = true
};

int __init wg_genetlink_init(void)
{
	BUILD_BUG_ON(WG_KEY_LEN != NOISE_PUBLIC_KEY_LEN);
	BUILD_BUG_ON(WG_KEY_LEN != NOISE_SYMMETRIC_KEY_LEN);

	return genl_register_family(&genl_family);
}

void __exit wg_genetlink_uninit(void)
{
	genl_unregister_family(&genl_family);
}