1 files changed, 414 insertions, 0 deletions

diff --git a/drivers/net/wireguard/send.c b/drivers/net/wireguard/send.c
new file mode 100644
index 000000000..0d48e0f4a
--- /dev/null
+++ b/drivers/net/wireguard/send.c
@@ -0,0 +1,414 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. 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(&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);
+}