![Jason A. Donenfeld](/assets/img/avatar_default.png)
We carry out checks to the effect of: if (skb->protocol != wg_examine_packet_protocol(skb)) goto err; By having wg_skb_examine_untrusted_ip_hdr return 0 on failure, this means that the check above still passes in the case where skb->protocol is zero, which is possible to hit with AF_PACKET: struct sockaddr_pkt saddr = { .spkt_device = "wg0" }; unsigned char buffer[5] = { 0 }; sendto(socket(AF_PACKET, SOCK_PACKET, /* skb->protocol = */ 0), buffer, sizeof(buffer), 0, (const struct sockaddr *)&saddr, sizeof(saddr)); Additional checks mean that this isn't actually a problem in the code base, but I could imagine it becoming a problem later if the function is used more liberally. I would prefer to fix this by having wg_examine_packet_protocol return a 32-bit ~0 value on failure, which will never match any value of skb->protocol, which would simply change the generated code from a mov to a movzx. However, sparse complains, and adding __force casts doesn't seem like a good idea, so instead we just add a simple helper function to check for the zero return value. Since wg_examine_packet_protocol itself gets inlined, this winds up not adding an additional branch to the generated code, since the 0 return value already happens in a mergable branch. Reported-by: Fabian Freyer <fabianfreyer@radicallyopensecurity.com> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: David S. Miller <davem@davemloft.net>
460 lines
12 KiB
C
460 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
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*/
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#include "queueing.h"
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#include "socket.h"
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#include "timers.h"
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#include "device.h"
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#include "ratelimiter.h"
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#include "peer.h"
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#include "messages.h"
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#include <linux/module.h>
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#include <linux/rtnetlink.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <linux/inetdevice.h>
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#include <linux/if_arp.h>
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#include <linux/icmp.h>
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#include <linux/suspend.h>
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#include <net/icmp.h>
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#include <net/rtnetlink.h>
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#include <net/ip_tunnels.h>
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#include <net/addrconf.h>
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static LIST_HEAD(device_list);
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static int wg_open(struct net_device *dev)
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{
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struct in_device *dev_v4 = __in_dev_get_rtnl(dev);
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struct inet6_dev *dev_v6 = __in6_dev_get(dev);
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struct wg_device *wg = netdev_priv(dev);
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struct wg_peer *peer;
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int ret;
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if (dev_v4) {
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/* At some point we might put this check near the ip_rt_send_
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* redirect call of ip_forward in net/ipv4/ip_forward.c, similar
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* to the current secpath check.
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*/
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IN_DEV_CONF_SET(dev_v4, SEND_REDIRECTS, false);
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IPV4_DEVCONF_ALL(dev_net(dev), SEND_REDIRECTS) = false;
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}
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if (dev_v6)
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dev_v6->cnf.addr_gen_mode = IN6_ADDR_GEN_MODE_NONE;
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ret = wg_socket_init(wg, wg->incoming_port);
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if (ret < 0)
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return ret;
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mutex_lock(&wg->device_update_lock);
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list_for_each_entry(peer, &wg->peer_list, peer_list) {
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wg_packet_send_staged_packets(peer);
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if (peer->persistent_keepalive_interval)
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wg_packet_send_keepalive(peer);
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}
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mutex_unlock(&wg->device_update_lock);
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return 0;
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}
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#ifdef CONFIG_PM_SLEEP
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static int wg_pm_notification(struct notifier_block *nb, unsigned long action,
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void *data)
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{
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struct wg_device *wg;
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struct wg_peer *peer;
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/* If the machine is constantly suspending and resuming, as part of
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* its normal operation rather than as a somewhat rare event, then we
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* don't actually want to clear keys.
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*/
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if (IS_ENABLED(CONFIG_PM_AUTOSLEEP) || IS_ENABLED(CONFIG_ANDROID))
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return 0;
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if (action != PM_HIBERNATION_PREPARE && action != PM_SUSPEND_PREPARE)
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return 0;
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rtnl_lock();
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list_for_each_entry(wg, &device_list, device_list) {
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mutex_lock(&wg->device_update_lock);
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list_for_each_entry(peer, &wg->peer_list, peer_list) {
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del_timer(&peer->timer_zero_key_material);
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wg_noise_handshake_clear(&peer->handshake);
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wg_noise_keypairs_clear(&peer->keypairs);
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}
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mutex_unlock(&wg->device_update_lock);
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}
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rtnl_unlock();
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rcu_barrier();
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return 0;
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}
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static struct notifier_block pm_notifier = { .notifier_call = wg_pm_notification };
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#endif
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static int wg_stop(struct net_device *dev)
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{
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struct wg_device *wg = netdev_priv(dev);
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struct wg_peer *peer;
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mutex_lock(&wg->device_update_lock);
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list_for_each_entry(peer, &wg->peer_list, peer_list) {
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wg_packet_purge_staged_packets(peer);
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wg_timers_stop(peer);
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wg_noise_handshake_clear(&peer->handshake);
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wg_noise_keypairs_clear(&peer->keypairs);
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wg_noise_reset_last_sent_handshake(&peer->last_sent_handshake);
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}
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mutex_unlock(&wg->device_update_lock);
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skb_queue_purge(&wg->incoming_handshakes);
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wg_socket_reinit(wg, NULL, NULL);
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return 0;
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}
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static netdev_tx_t wg_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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struct wg_device *wg = netdev_priv(dev);
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struct sk_buff_head packets;
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struct wg_peer *peer;
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struct sk_buff *next;
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sa_family_t family;
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u32 mtu;
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int ret;
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if (unlikely(!wg_check_packet_protocol(skb))) {
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ret = -EPROTONOSUPPORT;
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net_dbg_ratelimited("%s: Invalid IP packet\n", dev->name);
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goto err;
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}
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peer = wg_allowedips_lookup_dst(&wg->peer_allowedips, skb);
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if (unlikely(!peer)) {
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ret = -ENOKEY;
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if (skb->protocol == htons(ETH_P_IP))
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net_dbg_ratelimited("%s: No peer has allowed IPs matching %pI4\n",
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dev->name, &ip_hdr(skb)->daddr);
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else if (skb->protocol == htons(ETH_P_IPV6))
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net_dbg_ratelimited("%s: No peer has allowed IPs matching %pI6\n",
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dev->name, &ipv6_hdr(skb)->daddr);
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goto err;
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}
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family = READ_ONCE(peer->endpoint.addr.sa_family);
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if (unlikely(family != AF_INET && family != AF_INET6)) {
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ret = -EDESTADDRREQ;
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net_dbg_ratelimited("%s: No valid endpoint has been configured or discovered for peer %llu\n",
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dev->name, peer->internal_id);
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goto err_peer;
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}
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mtu = skb_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu;
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__skb_queue_head_init(&packets);
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if (!skb_is_gso(skb)) {
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skb_mark_not_on_list(skb);
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} else {
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struct sk_buff *segs = skb_gso_segment(skb, 0);
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if (unlikely(IS_ERR(segs))) {
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ret = PTR_ERR(segs);
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goto err_peer;
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}
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dev_kfree_skb(skb);
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skb = segs;
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}
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skb_list_walk_safe(skb, skb, next) {
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skb_mark_not_on_list(skb);
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skb = skb_share_check(skb, GFP_ATOMIC);
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if (unlikely(!skb))
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continue;
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/* We only need to keep the original dst around for icmp,
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* so at this point we're in a position to drop it.
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*/
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skb_dst_drop(skb);
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PACKET_CB(skb)->mtu = mtu;
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__skb_queue_tail(&packets, skb);
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}
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spin_lock_bh(&peer->staged_packet_queue.lock);
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/* If the queue is getting too big, we start removing the oldest packets
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* until it's small again. We do this before adding the new packet, so
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* we don't remove GSO segments that are in excess.
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*/
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while (skb_queue_len(&peer->staged_packet_queue) > MAX_STAGED_PACKETS) {
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dev_kfree_skb(__skb_dequeue(&peer->staged_packet_queue));
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++dev->stats.tx_dropped;
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}
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skb_queue_splice_tail(&packets, &peer->staged_packet_queue);
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spin_unlock_bh(&peer->staged_packet_queue.lock);
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wg_packet_send_staged_packets(peer);
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wg_peer_put(peer);
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return NETDEV_TX_OK;
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err_peer:
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wg_peer_put(peer);
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err:
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++dev->stats.tx_errors;
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if (skb->protocol == htons(ETH_P_IP))
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icmp_ndo_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
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else if (skb->protocol == htons(ETH_P_IPV6))
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icmpv6_ndo_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH, 0);
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kfree_skb(skb);
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return ret;
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}
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static const struct net_device_ops netdev_ops = {
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.ndo_open = wg_open,
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.ndo_stop = wg_stop,
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.ndo_start_xmit = wg_xmit,
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.ndo_get_stats64 = ip_tunnel_get_stats64
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};
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static void wg_destruct(struct net_device *dev)
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{
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struct wg_device *wg = netdev_priv(dev);
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rtnl_lock();
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list_del(&wg->device_list);
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rtnl_unlock();
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mutex_lock(&wg->device_update_lock);
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wg->incoming_port = 0;
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wg_socket_reinit(wg, NULL, NULL);
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/* The final references are cleared in the below calls to destroy_workqueue. */
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wg_peer_remove_all(wg);
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destroy_workqueue(wg->handshake_receive_wq);
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destroy_workqueue(wg->handshake_send_wq);
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destroy_workqueue(wg->packet_crypt_wq);
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wg_packet_queue_free(&wg->decrypt_queue, true);
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wg_packet_queue_free(&wg->encrypt_queue, true);
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rcu_barrier(); /* Wait for all the peers to be actually freed. */
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wg_ratelimiter_uninit();
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memzero_explicit(&wg->static_identity, sizeof(wg->static_identity));
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skb_queue_purge(&wg->incoming_handshakes);
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free_percpu(dev->tstats);
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free_percpu(wg->incoming_handshakes_worker);
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if (wg->have_creating_net_ref)
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put_net(wg->creating_net);
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kvfree(wg->index_hashtable);
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kvfree(wg->peer_hashtable);
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mutex_unlock(&wg->device_update_lock);
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pr_debug("%s: Interface deleted\n", dev->name);
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free_netdev(dev);
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}
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static const struct device_type device_type = { .name = KBUILD_MODNAME };
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static void wg_setup(struct net_device *dev)
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{
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struct wg_device *wg = netdev_priv(dev);
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enum { WG_NETDEV_FEATURES = NETIF_F_HW_CSUM | NETIF_F_RXCSUM |
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NETIF_F_SG | NETIF_F_GSO |
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NETIF_F_GSO_SOFTWARE | NETIF_F_HIGHDMA };
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const int overhead = MESSAGE_MINIMUM_LENGTH + sizeof(struct udphdr) +
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max(sizeof(struct ipv6hdr), sizeof(struct iphdr));
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dev->netdev_ops = &netdev_ops;
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dev->hard_header_len = 0;
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dev->addr_len = 0;
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dev->needed_headroom = DATA_PACKET_HEAD_ROOM;
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dev->needed_tailroom = noise_encrypted_len(MESSAGE_PADDING_MULTIPLE);
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dev->type = ARPHRD_NONE;
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dev->flags = IFF_POINTOPOINT | IFF_NOARP;
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dev->priv_flags |= IFF_NO_QUEUE;
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dev->features |= NETIF_F_LLTX;
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dev->features |= WG_NETDEV_FEATURES;
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dev->hw_features |= WG_NETDEV_FEATURES;
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dev->hw_enc_features |= WG_NETDEV_FEATURES;
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dev->mtu = ETH_DATA_LEN - overhead;
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dev->max_mtu = round_down(INT_MAX, MESSAGE_PADDING_MULTIPLE) - overhead;
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SET_NETDEV_DEVTYPE(dev, &device_type);
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/* We need to keep the dst around in case of icmp replies. */
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netif_keep_dst(dev);
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memset(wg, 0, sizeof(*wg));
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wg->dev = dev;
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}
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static int wg_newlink(struct net *src_net, struct net_device *dev,
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struct nlattr *tb[], struct nlattr *data[],
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struct netlink_ext_ack *extack)
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{
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struct wg_device *wg = netdev_priv(dev);
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int ret = -ENOMEM;
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wg->creating_net = src_net;
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init_rwsem(&wg->static_identity.lock);
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mutex_init(&wg->socket_update_lock);
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mutex_init(&wg->device_update_lock);
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skb_queue_head_init(&wg->incoming_handshakes);
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wg_allowedips_init(&wg->peer_allowedips);
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wg_cookie_checker_init(&wg->cookie_checker, wg);
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INIT_LIST_HEAD(&wg->peer_list);
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wg->device_update_gen = 1;
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wg->peer_hashtable = wg_pubkey_hashtable_alloc();
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if (!wg->peer_hashtable)
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return ret;
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wg->index_hashtable = wg_index_hashtable_alloc();
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if (!wg->index_hashtable)
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goto err_free_peer_hashtable;
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dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
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if (!dev->tstats)
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goto err_free_index_hashtable;
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wg->incoming_handshakes_worker =
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wg_packet_percpu_multicore_worker_alloc(
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wg_packet_handshake_receive_worker, wg);
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if (!wg->incoming_handshakes_worker)
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goto err_free_tstats;
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wg->handshake_receive_wq = alloc_workqueue("wg-kex-%s",
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WQ_CPU_INTENSIVE | WQ_FREEZABLE, 0, dev->name);
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if (!wg->handshake_receive_wq)
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goto err_free_incoming_handshakes;
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wg->handshake_send_wq = alloc_workqueue("wg-kex-%s",
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WQ_UNBOUND | WQ_FREEZABLE, 0, dev->name);
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if (!wg->handshake_send_wq)
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goto err_destroy_handshake_receive;
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wg->packet_crypt_wq = alloc_workqueue("wg-crypt-%s",
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WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM, 0, dev->name);
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if (!wg->packet_crypt_wq)
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goto err_destroy_handshake_send;
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ret = wg_packet_queue_init(&wg->encrypt_queue, wg_packet_encrypt_worker,
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true, MAX_QUEUED_PACKETS);
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if (ret < 0)
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goto err_destroy_packet_crypt;
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ret = wg_packet_queue_init(&wg->decrypt_queue, wg_packet_decrypt_worker,
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true, MAX_QUEUED_PACKETS);
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if (ret < 0)
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goto err_free_encrypt_queue;
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ret = wg_ratelimiter_init();
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if (ret < 0)
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goto err_free_decrypt_queue;
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ret = register_netdevice(dev);
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if (ret < 0)
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goto err_uninit_ratelimiter;
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list_add(&wg->device_list, &device_list);
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/* We wait until the end to assign priv_destructor, so that
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* register_netdevice doesn't call it for us if it fails.
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*/
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dev->priv_destructor = wg_destruct;
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pr_debug("%s: Interface created\n", dev->name);
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return ret;
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err_uninit_ratelimiter:
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wg_ratelimiter_uninit();
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err_free_decrypt_queue:
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wg_packet_queue_free(&wg->decrypt_queue, true);
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err_free_encrypt_queue:
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wg_packet_queue_free(&wg->encrypt_queue, true);
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err_destroy_packet_crypt:
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destroy_workqueue(wg->packet_crypt_wq);
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err_destroy_handshake_send:
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destroy_workqueue(wg->handshake_send_wq);
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err_destroy_handshake_receive:
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destroy_workqueue(wg->handshake_receive_wq);
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err_free_incoming_handshakes:
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free_percpu(wg->incoming_handshakes_worker);
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err_free_tstats:
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free_percpu(dev->tstats);
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err_free_index_hashtable:
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kvfree(wg->index_hashtable);
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err_free_peer_hashtable:
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kvfree(wg->peer_hashtable);
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return ret;
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}
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static struct rtnl_link_ops link_ops __read_mostly = {
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.kind = KBUILD_MODNAME,
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.priv_size = sizeof(struct wg_device),
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.setup = wg_setup,
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.newlink = wg_newlink,
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};
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static int wg_netdevice_notification(struct notifier_block *nb,
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unsigned long action, void *data)
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{
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struct net_device *dev = ((struct netdev_notifier_info *)data)->dev;
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struct wg_device *wg = netdev_priv(dev);
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ASSERT_RTNL();
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if (action != NETDEV_REGISTER || dev->netdev_ops != &netdev_ops)
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return 0;
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if (dev_net(dev) == wg->creating_net && wg->have_creating_net_ref) {
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put_net(wg->creating_net);
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wg->have_creating_net_ref = false;
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} else if (dev_net(dev) != wg->creating_net &&
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!wg->have_creating_net_ref) {
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wg->have_creating_net_ref = true;
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get_net(wg->creating_net);
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}
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return 0;
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}
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static struct notifier_block netdevice_notifier = {
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.notifier_call = wg_netdevice_notification
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};
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int __init wg_device_init(void)
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{
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int ret;
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#ifdef CONFIG_PM_SLEEP
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ret = register_pm_notifier(&pm_notifier);
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if (ret)
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return ret;
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#endif
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ret = register_netdevice_notifier(&netdevice_notifier);
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if (ret)
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goto error_pm;
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ret = rtnl_link_register(&link_ops);
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if (ret)
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goto error_netdevice;
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return 0;
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error_netdevice:
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unregister_netdevice_notifier(&netdevice_notifier);
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error_pm:
|
|
#ifdef CONFIG_PM_SLEEP
|
|
unregister_pm_notifier(&pm_notifier);
|
|
#endif
|
|
return ret;
|
|
}
|
|
|
|
void wg_device_uninit(void)
|
|
{
|
|
rtnl_link_unregister(&link_ops);
|
|
unregister_netdevice_notifier(&netdevice_notifier);
|
|
#ifdef CONFIG_PM_SLEEP
|
|
unregister_pm_notifier(&pm_notifier);
|
|
#endif
|
|
rcu_barrier();
|
|
}
|