// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2015-2019 Jason A. Donenfeld <[email protected]>. All Rights Reserved.
*/
#include "queueing.h"
#include "timers.h"
#include "device.h"
#include "peer.h"
#include "socket.h"
#include "messages.h"
#include "cookie.h"
#include <linux/uio.h>
#include <linux/inetdevice.h>
#include <linux/socket.h>
#include <net/ip_tunnels.h>
#include <net/udp.h>
#include <net/sock.h>
static void wg_packet_send_handshake_initiation(struct wg_peer *peer)
{
struct message_handshake_initiation packet;
if (!wg_birthdate_has_expired(atomic64_read(&peer->last_sent_handshake),
REKEY_TIMEOUT))
return; /* This function is rate limited. */
atomic64_set(&peer->last_sent_handshake, ktime_get_coarse_boottime_ns());
net_dbg_ratelimited("%s: Sending handshake initiation to peer %llu (%pISpfsc)\n",
peer->device->dev->name, peer->internal_id,
&peer->endpoint.addr);
if (wg_noise_handshake_create_initiation(&packet, &peer->handshake)) {
wg_cookie_add_mac_to_packet(&packet, sizeof(packet), peer);
wg_timers_any_authenticated_packet_traversal(peer);
wg_timers_any_authenticated_packet_sent(peer);
atomic64_set(&peer->last_sent_handshake,
ktime_get_coarse_boottime_ns());
wg_socket_send_buffer_to_peer(peer, &packet, sizeof(packet),
HANDSHAKE_DSCP);
wg_timers_handshake_initiated(peer);
}
}
void wg_packet_handshake_send_worker(struct work_struct *work)
{
struct wg_peer *peer = container_of(work, struct wg_peer,
transmit_handshake_work);
wg_packet_send_handshake_initiation(peer);
wg_peer_put(peer);
}
void wg_packet_send_queued_handshake_initiation(struct wg_peer *peer,
bool is_retry)
{
if (!is_retry)
peer->timer_handshake_attempts = 0;
rcu_read_lock_bh();
/* We check last_sent_handshake here in addition to the actual function
* we're queueing up, so that we don't queue things if not strictly
* necessary:
*/
if (!wg_birthdate_has_expired(atomic64_read(&peer->last_sent_handshake),
REKEY_TIMEOUT) ||
unlikely(READ_ONCE(peer->is_dead)))
goto out;
wg_peer_get(peer);
/* Queues up calling packet_send_queued_handshakes(peer), where we do a
* peer_put(peer) after:
*/
if (!queue_work(peer->device->handshake_send_wq,
&peer->transmit_handshake_work))
/* If the work was already queued, we want to drop the
* extra reference:
*/
wg_peer_put(peer);
out:
rcu_read_unlock_bh();
}
void wg_packet_send_handshake_response(struct wg_peer *peer)
{
struct message_handshake_response packet;
atomic64_set(&peer->last_sent_handshake, ktime_get_coarse_boottime_ns());
net_dbg_ratelimited("%s: Sending handshake response to peer %llu (%pISpfsc)\n",
peer->device->dev->name, peer->internal_id,
&peer->endpoint.addr);
if (wg_noise_handshake_create_response(&packet, &peer->handshake)) {
wg_cookie_add_mac_to_packet(&packet, sizeof(packet), peer);
if (wg_noise_handshake_begin_session(&peer->handshake,
&peer->keypairs)) {
wg_timers_session_derived(peer);
wg_timers_any_authenticated_packet_traversal(peer);
wg_timers_any_authenticated_packet_sent(peer);
atomic64_set(&peer->last_sent_handshake,
ktime_get_coarse_boottime_ns());
wg_socket_send_buffer_to_peer(peer, &packet,
sizeof(packet),
HANDSHAKE_DSCP);
}
}
}
void wg_packet_send_handshake_cookie(struct wg_device *wg,
struct sk_buff *initiating_skb,
__le32 sender_index)
{
struct message_handshake_cookie packet;
net_dbg_skb_ratelimited("%s: Sending cookie response for denied handshake message for %pISpfsc\n",
wg->dev->name, initiating_skb);
wg_cookie_message_create(&packet, initiating_skb, sender_index,
&wg->cookie_checker);
wg_socket_send_buffer_as_reply_to_skb(wg, initiating_skb, &packet,
sizeof(packet));
}
static void keep_key_fresh(struct wg_peer *peer)
{
struct noise_keypair *keypair;
bool send;
rcu_read_lock_bh();
keypair = rcu_dereference_bh(peer->keypairs.current_keypair);
send = keypair && READ_ONCE(keypair->sending.is_valid) &&
(atomic64_read(&keypair->sending_counter) > REKEY_AFTER_MESSAGES ||
(keypair->i_am_the_initiator &&
wg_birthdate_has_expired(keypair->sending.birthdate, REKEY_AFTER_TIME)));
rcu_read_unlock_bh();
if (unlikely(send))
wg_packet_send_queued_handshake_initiation(peer, false);
}
static unsigned int calculate_skb_padding(struct sk_buff *skb)
{
unsigned int padded_size, last_unit = skb->len;
if (unlikely(!PACKET_CB(skb)->mtu))
return ALIGN(last_unit, MESSAGE_PADDING_MULTIPLE) - last_unit;
/* We do this modulo business with the MTU, just in case the networking
* layer gives us a packet that's bigger than the MTU. In that case, we
* wouldn't want the final subtraction to overflow in the case of the
* padded_size being clamped. Fortunately, that's very rarely the case,
* so we optimize for that not happening.
*/
if (unlikely(last_unit > PACKET_CB(skb)->mtu))
last_unit %= PACKET_CB(skb)->mtu;
padded_size = min(PACKET_CB(skb)->mtu,
ALIGN(last_unit, MESSAGE_PADDING_MULTIPLE));
return padded_size - last_unit;
}
static bool encrypt_packet(struct sk_buff *skb, struct noise_keypair *keypair)
{
unsigned int padding_len, plaintext_len, trailer_len;
struct scatterlist sg[MAX_SKB_FRAGS + 8];
struct message_data *header;
struct sk_buff *trailer;
int num_frags;
/* Force hash calculation before encryption so that flow analysis is
* consistent over the inner packet.
*/
skb_get_hash(skb);
/* Calculate lengths. */
padding_len = calculate_skb_padding(skb);
trailer_len = padding_len + noise_encrypted_len(0);
plaintext_len = skb->len + padding_len;
/* Expand data section to have room for padding and auth tag. */
num_frags = skb_cow_data(skb, trailer_len, &trailer);
if (unlikely(num_frags < 0 || num_frags > ARRAY_SIZE(sg)))
return false;
/* Set the padding to zeros, and make sure it and the auth tag are part
* of the skb.
*/
memset(skb_tail_pointer(trailer), 0, padding_len);
/* Expand head section to have room for our header and the network
* stack's headers.
*/
if (unlikely(skb_cow_head(skb, DATA_PACKET_HEAD_ROOM) < 0))
return false;
/* Finalize checksum calculation for the inner packet, if required. */
if (unlikely(skb->ip_summed == CHECKSUM_PARTIAL &&
skb_checksum_help(skb)))
return false;
/* Only after checksumming can we safely add on the padding at the end
* and the header.
*/
skb_set_inner_network_header(skb, 0);
header = (struct message_data *)skb_push(skb, sizeof(*header));
header->header.type = cpu_to_le32(MESSAGE_DATA);
header->key_idx = keypair->remote_index;
header->counter = cpu_to_le64(PACKET_CB(skb)->nonce);
pskb_put(skb, trailer, trailer_len);
/* Now we can encrypt the scattergather segments */
sg_init_table(sg, num_frags);
if (skb_to_sgvec(skb, sg, sizeof(struct message_data),
noise_encrypted_len(plaintext_len)) <= 0)
return false;
return chacha20poly1305_encrypt_sg_inplace(sg, plaintext_len, NULL, 0,
PACKET_CB(skb)->nonce,
keypair->sending.key);
}
void wg_packet_send_keepalive(struct wg_peer *peer)
{
struct sk_buff *skb;
if (skb_queue_empty_lockless(&peer->staged_packet_queue)) {
skb = alloc_skb(DATA_PACKET_HEAD_ROOM + MESSAGE_MINIMUM_LENGTH,
GFP_ATOMIC);
if (unlikely(!skb))
return;
skb_reserve(skb, DATA_PACKET_HEAD_ROOM);
skb->dev = peer->device->dev;
PACKET_CB(skb)->mtu = skb->dev->mtu;
skb_queue_tail(&peer->staged_packet_queue, skb);
net_dbg_ratelimited("%s: Sending keepalive packet to peer %llu (%pISpfsc)\n",
peer->device->dev->name, peer->internal_id,
&peer->endpoint.addr);
}
wg_packet_send_staged_packets(peer);
}
static void wg_packet_create_data_done(struct wg_peer *peer, struct sk_buff *first)
{
struct sk_buff *skb, *next;
bool is_keepalive, data_sent = false;
wg_timers_any_authenticated_packet_traversal(peer);
wg_timers_any_authenticated_packet_sent(peer);
skb_list_walk_safe(first, skb, next) {
is_keepalive = skb->len == message_data_len(0);
if (likely(!wg_socket_send_skb_to_peer(peer, skb,
PACKET_CB(skb)->ds) && !is_keepalive))
data_sent = true;
}
if (likely(data_sent))
wg_timers_data_sent(peer);
keep_key_fresh(peer);
}
void wg_packet_tx_worker(struct work_struct *work)
{
struct wg_peer *peer = container_of(work, struct wg_peer, transmit_packet_work);
struct noise_keypair *keypair;
enum packet_state state;
struct sk_buff *first;
while ((first = wg_prev_queue_peek(&peer->tx_queue)) != NULL &&
(state = atomic_read_acquire(&PACKET_CB(first)->state)) !=
PACKET_STATE_UNCRYPTED) {
wg_prev_queue_drop_peeked(&peer->tx_queue);
keypair = PACKET_CB(first)->keypair;
if (likely(state == PACKET_STATE_CRYPTED))
wg_packet_create_data_done(peer, first);
else
kfree_skb_list(first);
wg_noise_keypair_put(keypair, false);
wg_peer_put(peer);
if (need_resched())
cond_resched();
}
}
void wg_packet_encrypt_worker(struct work_struct *work)
{
struct crypt_queue *queue = container_of(work, struct multicore_worker,
work)->ptr;
struct sk_buff *first, *skb, *next;
while ((first = ptr_ring_consume_bh(&queue->ring)) != NULL) {
enum packet_state state = PACKET_STATE_CRYPTED;
skb_list_walk_safe(first, skb, next) {
if (likely(encrypt_packet(skb,
PACKET_CB(first)->keypair))) {
wg_reset_packet(skb, true);
} else {
state = PACKET_STATE_DEAD;
break;
}
}
wg_queue_enqueue_per_peer_tx(first, state);
if (need_resched())
cond_resched();
}
}
static void wg_packet_create_data(struct wg_peer *peer, struct sk_buff *first)
{
struct wg_device *wg = peer->device;
int ret = -EINVAL;
rcu_read_lock_bh();
if (unlikely(READ_ONCE(peer->is_dead)))
goto err;
ret = wg_queue_enqueue_per_device_and_peer(&wg->encrypt_queue, &peer->tx_queue, first,
wg->packet_crypt_wq);
if (unlikely(ret == -EPIPE))
wg_queue_enqueue_per_peer_tx(first, PACKET_STATE_DEAD);
err:
rcu_read_unlock_bh();
if (likely(!ret || ret == -EPIPE))
return;
wg_noise_keypair_put(PACKET_CB(first)->keypair, false);
wg_peer_put(peer);
kfree_skb_list(first);
}
void wg_packet_purge_staged_packets(struct wg_peer *peer)
{
spin_lock_bh(&peer->staged_packet_queue.lock);
DEV_STATS_ADD(peer->device->dev, tx_dropped,
peer->staged_packet_queue.qlen);
__skb_queue_purge(&peer->staged_packet_queue);
spin_unlock_bh(&peer->staged_packet_queue.lock);
}
void wg_packet_send_staged_packets(struct wg_peer *peer)
{
struct noise_keypair *keypair;
struct sk_buff_head packets;
struct sk_buff *skb;
/* Steal the current queue into our local one. */
__skb_queue_head_init(&packets);
spin_lock_bh(&peer->staged_packet_queue.lock);
skb_queue_splice_init(&peer->staged_packet_queue, &packets);
spin_unlock_bh(&peer->staged_packet_queue.lock);
if (unlikely(skb_queue_empty(&packets)))
return;
/* First we make sure we have a valid reference to a valid key. */
rcu_read_lock_bh();
keypair = wg_noise_keypair_get(
rcu_dereference_bh(peer->keypairs.current_keypair));
rcu_read_unlock_bh();
if (unlikely(!keypair))
goto out_nokey;
if (unlikely(!READ_ONCE(keypair->sending.is_valid)))
goto out_nokey;
if (unlikely(wg_birthdate_has_expired(keypair->sending.birthdate,
REJECT_AFTER_TIME)))
goto out_invalid;
/* After we know we have a somewhat valid key, we now try to assign
* nonces to all of the packets in the queue. If we can't assign nonces
* for all of them, we just consider it a failure and wait for the next
* handshake.
*/
skb_queue_walk(&packets, skb) {
/* 0 for no outer TOS: no leak. TODO: at some later point, we
* might consider using flowi->tos as outer instead.
*/
PACKET_CB(skb)->ds = ip_tunnel_ecn_encap(0, ip_hdr(skb), skb);
PACKET_CB(skb)->nonce =
atomic64_inc_return(&keypair->sending_counter) - 1;
if (unlikely(PACKET_CB(skb)->nonce >= REJECT_AFTER_MESSAGES))
goto out_invalid;
}
packets.prev->next = NULL;
wg_peer_get(keypair->entry.peer);
PACKET_CB(packets.next)->keypair = keypair;
wg_packet_create_data(peer, packets.next);
return;
out_invalid:
WRITE_ONCE(keypair->sending.is_valid, false);
out_nokey:
wg_noise_keypair_put(keypair, false);
/* We orphan the packets if we're waiting on a handshake, so that they
* don't block a socket's pool.
*/
skb_queue_walk(&packets, skb)
skb_orphan(skb);
/* Then we put them back on the top of the queue. We're not too
* concerned about accidentally getting things a little out of order if
* packets are being added really fast, because this queue is for before
* packets can even be sent and it's small anyway.
*/
spin_lock_bh(&peer->staged_packet_queue.lock);
skb_queue_splice(&packets, &peer->staged_packet_queue);
spin_unlock_bh(&peer->staged_packet_queue.lock);
/* If we're exiting because there's something wrong with the key, it
* means we should initiate a new handshake.
*/
wg_packet_send_queued_handshake_initiation(peer, false);
}
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