1 files changed, 595 insertions, 0 deletions

diff --git a/drivers/net/wireguard/receive.c b/drivers/net/wireguard/receive.c
new file mode 100644
index 000000000000..7e675f541491
--- /dev/null
+++ b/drivers/net/wireguard/receive.c
@@ -0,0 +1,595 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#include "queueing.h"
+#include "device.h"
+#include "peer.h"
+#include "timers.h"
+#include "messages.h"
+#include "cookie.h"
+#include "socket.h"
+
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/udp.h>
+#include <net/ip_tunnels.h>
+
+/* Must be called with bh disabled. */
+static void update_rx_stats(struct wg_peer *peer, size_t len)
+{
+	struct pcpu_sw_netstats *tstats =
+		get_cpu_ptr(peer->device->dev->tstats);
+
+	u64_stats_update_begin(&tstats->syncp);
+	++tstats->rx_packets;
+	tstats->rx_bytes += len;
+	peer->rx_bytes += len;
+	u64_stats_update_end(&tstats->syncp);
+	put_cpu_ptr(tstats);
+}
+
+#define SKB_TYPE_LE32(skb) (((struct message_header *)(skb)->data)->type)
+
+static size_t validate_header_len(struct sk_buff *skb)
+{
+	if (unlikely(skb->len < sizeof(struct message_header)))
+		return 0;
+	if (SKB_TYPE_LE32(skb) == cpu_to_le32(MESSAGE_DATA) &&
+	    skb->len >= MESSAGE_MINIMUM_LENGTH)
+		return sizeof(struct message_data);
+	if (SKB_TYPE_LE32(skb) == cpu_to_le32(MESSAGE_HANDSHAKE_INITIATION) &&
+	    skb->len == sizeof(struct message_handshake_initiation))
+		return sizeof(struct message_handshake_initiation);
+	if (SKB_TYPE_LE32(skb) == cpu_to_le32(MESSAGE_HANDSHAKE_RESPONSE) &&
+	    skb->len == sizeof(struct message_handshake_response))
+		return sizeof(struct message_handshake_response);
+	if (SKB_TYPE_LE32(skb) == cpu_to_le32(MESSAGE_HANDSHAKE_COOKIE) &&
+	    skb->len == sizeof(struct message_handshake_cookie))
+		return sizeof(struct message_handshake_cookie);
+	return 0;
+}
+
+static int prepare_skb_header(struct sk_buff *skb, struct wg_device *wg)
+{
+	size_t data_offset, data_len, header_len;
+	struct udphdr *udp;
+
+	if (unlikely(wg_skb_examine_untrusted_ip_hdr(skb) != skb->protocol ||
+		     skb_transport_header(skb) < skb->head ||
+		     (skb_transport_header(skb) + sizeof(struct udphdr)) >
+			     skb_tail_pointer(skb)))
+		return -EINVAL; /* Bogus IP header */
+	udp = udp_hdr(skb);
+	data_offset = (u8 *)udp - skb->data;
+	if (unlikely(data_offset > U16_MAX ||
+		     data_offset + sizeof(struct udphdr) > skb->len))
+		/* Packet has offset at impossible location or isn't big enough
+		 * to have UDP fields.
+		 */
+		return -EINVAL;
+	data_len = ntohs(udp->len);
+	if (unlikely(data_len < sizeof(struct udphdr) ||
+		     data_len > skb->len - data_offset))
+		/* UDP packet is reporting too small of a size or lying about
+		 * its size.
+		 */
+		return -EINVAL;
+	data_len -= sizeof(struct udphdr);
+	data_offset = (u8 *)udp + sizeof(struct udphdr) - skb->data;
+	if (unlikely(!pskb_may_pull(skb,
+				data_offset + sizeof(struct message_header)) ||
+		     pskb_trim(skb, data_len + data_offset) < 0))
+		return -EINVAL;
+	skb_pull(skb, data_offset);
+	if (unlikely(skb->len != data_len))
+		/* Final len does not agree with calculated len */
+		return -EINVAL;
+	header_len = validate_header_len(skb);
+	if (unlikely(!header_len))
+		return -EINVAL;
+	__skb_push(skb, data_offset);
+	if (unlikely(!pskb_may_pull(skb, data_offset + header_len)))
+		return -EINVAL;
+	__skb_pull(skb, data_offset);
+	return 0;
+}
+
+static void wg_receive_handshake_packet(struct wg_device *wg,
+					struct sk_buff *skb)
+{
+	enum cookie_mac_state mac_state;
+	struct wg_peer *peer = NULL;
+	/* This is global, so that our load calculation applies to the whole
+	 * system. We don't care about races with it at all.
+	 */
+	static u64 last_under_load;
+	bool packet_needs_cookie;
+	bool under_load;
+
+	if (SKB_TYPE_LE32(skb) == cpu_to_le32(MESSAGE_HANDSHAKE_COOKIE)) {
+		net_dbg_skb_ratelimited("%s: Receiving cookie response from %pISpfsc\n",
+					wg->dev->name, skb);
+		wg_cookie_message_consume(
+			(struct message_handshake_cookie *)skb->data, wg);
+		return;
+	}
+
+	under_load = skb_queue_len(&wg->incoming_handshakes) >=
+		     MAX_QUEUED_INCOMING_HANDSHAKES / 8;
+	if (under_load)
+		last_under_load = ktime_get_coarse_boottime_ns();
+	else if (last_under_load)
+		under_load = !wg_birthdate_has_expired(last_under_load, 1);
+	mac_state = wg_cookie_validate_packet(&wg->cookie_checker, skb,
+					      under_load);
+	if ((under_load && mac_state == VALID_MAC_WITH_COOKIE) ||
+	    (!under_load && mac_state == VALID_MAC_BUT_NO_COOKIE)) {
+		packet_needs_cookie = false;
+	} else if (under_load && mac_state == VALID_MAC_BUT_NO_COOKIE) {
+		packet_needs_cookie = true;
+	} else {
+		net_dbg_skb_ratelimited("%s: Invalid MAC of handshake, dropping packet from %pISpfsc\n",
+					wg->dev->name, skb);
+		return;
+	}
+
+	switch (SKB_TYPE_LE32(skb)) {
+	case cpu_to_le32(MESSAGE_HANDSHAKE_INITIATION): {
+		struct message_handshake_initiation *message =
+			(struct message_handshake_initiation *)skb->data;
+
+		if (packet_needs_cookie) {
+			wg_packet_send_handshake_cookie(wg, skb,
+							message->sender_index);
+			return;
+		}
+		peer = wg_noise_handshake_consume_initiation(message, wg);
+		if (unlikely(!peer)) {
+			net_dbg_skb_ratelimited("%s: Invalid handshake initiation from %pISpfsc\n",
+						wg->dev->name, skb);
+			return;
+		}
+		wg_socket_set_peer_endpoint_from_skb(peer, skb);
+		net_dbg_ratelimited("%s: Receiving handshake initiation from peer %llu (%pISpfsc)\n",
+				    wg->dev->name, peer->internal_id,
+				    &peer->endpoint.addr);
+		wg_packet_send_handshake_response(peer);
+		break;
+	}
+	case cpu_to_le32(MESSAGE_HANDSHAKE_RESPONSE): {
+		struct message_handshake_response *message =
+			(struct message_handshake_response *)skb->data;
+
+		if (packet_needs_cookie) {
+			wg_packet_send_handshake_cookie(wg, skb,
+							message->sender_index);
+			return;
+		}
+		peer = wg_noise_handshake_consume_response(message, wg);
+		if (unlikely(!peer)) {
+			net_dbg_skb_ratelimited("%s: Invalid handshake response from %pISpfsc\n",
+						wg->dev->name, skb);
+			return;
+		}
+		wg_socket_set_peer_endpoint_from_skb(peer, skb);
+		net_dbg_ratelimited("%s: Receiving handshake response from peer %llu (%pISpfsc)\n",
+				    wg->dev->name, peer->internal_id,
+				    &peer->endpoint.addr);
+		if (wg_noise_handshake_begin_session(&peer->handshake,
+						     &peer->keypairs)) {
+			wg_timers_session_derived(peer);
+			wg_timers_handshake_complete(peer);
+			/* Calling this function will either send any existing
+			 * packets in the queue and not send a keepalive, which
+			 * is the best case, Or, if there's nothing in the
+			 * queue, it will send a keepalive, in order to give
+			 * immediate confirmation of the session.
+			 */
+			wg_packet_send_keepalive(peer);
+		}
+		break;
+	}
+	}
+
+	if (unlikely(!peer)) {
+		WARN(1, "Somehow a wrong type of packet wound up in the handshake queue!\n");
+		return;
+	}
+
+	local_bh_disable();
+	update_rx_stats(peer, skb->len);
+	local_bh_enable();
+
+	wg_timers_any_authenticated_packet_received(peer);
+	wg_timers_any_authenticated_packet_traversal(peer);
+	wg_peer_put(peer);
+}
+
+void wg_packet_handshake_receive_worker(struct work_struct *work)
+{
+	struct wg_device *wg = container_of(work, struct multicore_worker,
+					    work)->ptr;
+	struct sk_buff *skb;
+
+	while ((skb = skb_dequeue(&wg->incoming_handshakes)) != NULL) {
+		wg_receive_handshake_packet(wg, skb);
+		dev_kfree_skb(skb);
+		cond_resched();
+	}
+}
+
+static void keep_key_fresh(struct wg_peer *peer)
+{
+	struct noise_keypair *keypair;
+	bool send = false;
+
+	if (peer->sent_lastminute_handshake)
+		return;
+
+	rcu_read_lock_bh();
+	keypair = rcu_dereference_bh(peer->keypairs.current_keypair);
+	if (likely(keypair && READ_ONCE(keypair->sending.is_valid)) &&
+	    keypair->i_am_the_initiator &&
+	    unlikely(wg_birthdate_has_expired(keypair->sending.birthdate,
+			REJECT_AFTER_TIME - KEEPALIVE_TIMEOUT - REKEY_TIMEOUT)))
+		send = true;
+	rcu_read_unlock_bh();
+
+	if (send) {
+		peer->sent_lastminute_handshake = true;
+		wg_packet_send_queued_handshake_initiation(peer, false);
+	}
+}
+
+static bool decrypt_packet(struct sk_buff *skb, struct noise_symmetric_key *key)
+{
+	struct scatterlist sg[MAX_SKB_FRAGS + 8];
+	struct sk_buff *trailer;
+	unsigned int offset;
+	int num_frags;
+
+	if (unlikely(!key))
+		return false;
+
+	if (unlikely(!READ_ONCE(key->is_valid) ||
+		  wg_birthdate_has_expired(key->birthdate, REJECT_AFTER_TIME) ||
+		  key->counter.receive.counter >= REJECT_AFTER_MESSAGES)) {
+		WRITE_ONCE(key->is_valid, false);
+		return false;
+	}
+
+	PACKET_CB(skb)->nonce =
+		le64_to_cpu(((struct message_data *)skb->data)->counter);
+
+	/* We ensure that the network header is part of the packet before we
+	 * call skb_cow_data, so that there's no chance that data is removed
+	 * from the skb, so that later we can extract the original endpoint.
+	 */
+	offset = skb->data - skb_network_header(skb);
+	skb_push(skb, offset);
+	num_frags = skb_cow_data(skb, 0, &trailer);
+	offset += sizeof(struct message_data);
+	skb_pull(skb, offset);
+	if (unlikely(num_frags < 0 || num_frags > ARRAY_SIZE(sg)))
+		return false;
+
+	sg_init_table(sg, num_frags);
+	if (skb_to_sgvec(skb, sg, 0, skb->len) <= 0)
+		return false;
+
+	if (!chacha20poly1305_decrypt_sg_inplace(sg, skb->len, NULL, 0,
+					         PACKET_CB(skb)->nonce,
+						 key->key))
+		return false;
+
+	/* Another ugly situation of pushing and pulling the header so as to
+	 * keep endpoint information intact.
+	 */
+	skb_push(skb, offset);
+	if (pskb_trim(skb, skb->len - noise_encrypted_len(0)))
+		return false;
+	skb_pull(skb, offset);
+
+	return true;
+}
+
+/* This is RFC6479, a replay detection bitmap algorithm that avoids bitshifts */
+static bool counter_validate(union noise_counter *counter, u64 their_counter)
+{
+	unsigned long index, index_current, top, i;
+	bool ret = false;
+
+	spin_lock_bh(&counter->receive.lock);
+
+	if (unlikely(counter->receive.counter >= REJECT_AFTER_MESSAGES + 1 ||
+		     their_counter >= REJECT_AFTER_MESSAGES))
+		goto out;
+
+	++their_counter;
+
+	if (unlikely((COUNTER_WINDOW_SIZE + their_counter) <
+		     counter->receive.counter))
+		goto out;
+
+	index = their_counter >> ilog2(BITS_PER_LONG);
+
+	if (likely(their_counter > counter->receive.counter)) {
+		index_current = counter->receive.counter >> ilog2(BITS_PER_LONG);
+		top = min_t(unsigned long, index - index_current,
+			    COUNTER_BITS_TOTAL / BITS_PER_LONG);
+		for (i = 1; i <= top; ++i)
+			counter->receive.backtrack[(i + index_current) &
+				((COUNTER_BITS_TOTAL / BITS_PER_LONG) - 1)] = 0;
+		counter->receive.counter = their_counter;
+	}
+
+	index &= (COUNTER_BITS_TOTAL / BITS_PER_LONG) - 1;
+	ret = !test_and_set_bit(their_counter & (BITS_PER_LONG - 1),
+				&counter->receive.backtrack[index]);
+
+out:
+	spin_unlock_bh(&counter->receive.lock);
+	return ret;
+}
+
+#include "selftest/counter.c"
+
+static void wg_packet_consume_data_done(struct wg_peer *peer,
+					struct sk_buff *skb,
+					struct endpoint *endpoint)
+{
+	struct net_device *dev = peer->device->dev;
+	unsigned int len, len_before_trim;
+	struct wg_peer *routed_peer;
+
+	wg_socket_set_peer_endpoint(peer, endpoint);
+
+	if (unlikely(wg_noise_received_with_keypair(&peer->keypairs,
+						    PACKET_CB(skb)->keypair))) {
+		wg_timers_handshake_complete(peer);
+		wg_packet_send_staged_packets(peer);
+	}
+
+	keep_key_fresh(peer);
+
+	wg_timers_any_authenticated_packet_received(peer);
+	wg_timers_any_authenticated_packet_traversal(peer);
+
+	/* A packet with length 0 is a keepalive packet */
+	if (unlikely(!skb->len)) {
+		update_rx_stats(peer, message_data_len(0));
+		net_dbg_ratelimited("%s: Receiving keepalive packet from peer %llu (%pISpfsc)\n",
+				    dev->name, peer->internal_id,
+				    &peer->endpoint.addr);
+		goto packet_processed;
+	}
+
+	wg_timers_data_received(peer);
+
+	if (unlikely(skb_network_header(skb) < skb->head))
+		goto dishonest_packet_size;
+	if (unlikely(!(pskb_network_may_pull(skb, sizeof(struct iphdr)) &&
+		       (ip_hdr(skb)->version == 4 ||
+			(ip_hdr(skb)->version == 6 &&
+			 pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))))))
+		goto dishonest_packet_type;
+
+	skb->dev = dev;
+	/* We've already verified the Poly1305 auth tag, which means this packet
+	 * was not modified in transit. We can therefore tell the networking
+	 * stack that all checksums of every layer of encapsulation have already
+	 * been checked "by the hardware" and therefore is unneccessary to check
+	 * again in software.
+	 */
+	skb->ip_summed = CHECKSUM_UNNECESSARY;
+	skb->csum_level = ~0; /* All levels */
+	skb->protocol = wg_skb_examine_untrusted_ip_hdr(skb);
+	if (skb->protocol == htons(ETH_P_IP)) {
+		len = ntohs(ip_hdr(skb)->tot_len);
+		if (unlikely(len < sizeof(struct iphdr)))
+			goto dishonest_packet_size;
+		if (INET_ECN_is_ce(PACKET_CB(skb)->ds))
+			IP_ECN_set_ce(ip_hdr(skb));
+	} else if (skb->protocol == htons(ETH_P_IPV6)) {
+		len = ntohs(ipv6_hdr(skb)->payload_len) +
+		      sizeof(struct ipv6hdr);
+		if (INET_ECN_is_ce(PACKET_CB(skb)->ds))
+			IP6_ECN_set_ce(skb, ipv6_hdr(skb));
+	} else {
+		goto dishonest_packet_type;
+	}
+
+	if (unlikely(len > skb->len))
+		goto dishonest_packet_size;
+	len_before_trim = skb->len;
+	if (unlikely(pskb_trim(skb, len)))
+		goto packet_processed;
+
+	routed_peer = wg_allowedips_lookup_src(&peer->device->peer_allowedips,
+					       skb);
+	wg_peer_put(routed_peer); /* We don't need the extra reference. */
+
+	if (unlikely(routed_peer != peer))
+		goto dishonest_packet_peer;
+
+	if (unlikely(napi_gro_receive(&peer->napi, skb) == GRO_DROP)) {
+		++dev->stats.rx_dropped;
+		net_dbg_ratelimited("%s: Failed to give packet to userspace from peer %llu (%pISpfsc)\n",
+				    dev->name, peer->internal_id,
+				    &peer->endpoint.addr);
+	} else {
+		update_rx_stats(peer, message_data_len(len_before_trim));
+	}
+	return;
+
+dishonest_packet_peer:
+	net_dbg_skb_ratelimited("%s: Packet has unallowed src IP (%pISc) from peer %llu (%pISpfsc)\n",
+				dev->name, skb, peer->internal_id,
+				&peer->endpoint.addr);
+	++dev->stats.rx_errors;
+	++dev->stats.rx_frame_errors;
+	goto packet_processed;
+dishonest_packet_type:
+	net_dbg_ratelimited("%s: Packet is neither ipv4 nor ipv6 from peer %llu (%pISpfsc)\n",
+			    dev->name, peer->internal_id, &peer->endpoint.addr);
+	++dev->stats.rx_errors;
+	++dev->stats.rx_frame_errors;
+	goto packet_processed;
+dishonest_packet_size:
+	net_dbg_ratelimited("%s: Packet has incorrect size from peer %llu (%pISpfsc)\n",
+			    dev->name, peer->internal_id, &peer->endpoint.addr);
+	++dev->stats.rx_errors;
+	++dev->stats.rx_length_errors;
+	goto packet_processed;
+packet_processed:
+	dev_kfree_skb(skb);
+}
+
+int wg_packet_rx_poll(struct napi_struct *napi, int budget)
+{
+	struct wg_peer *peer = container_of(napi, struct wg_peer, napi);
+	struct crypt_queue *queue = &peer->rx_queue;
+	struct noise_keypair *keypair;
+	struct endpoint endpoint;
+	enum packet_state state;
+	struct sk_buff *skb;
+	int work_done = 0;
+	bool free;
+
+	if (unlikely(budget <= 0))
+		return 0;
+
+	while ((skb = __ptr_ring_peek(&queue->ring)) != NULL &&
+	       (state = atomic_read_acquire(&PACKET_CB(skb)->state)) !=
+		       PACKET_STATE_UNCRYPTED) {
+		__ptr_ring_discard_one(&queue->ring);
+		peer = PACKET_PEER(skb);
+		keypair = PACKET_CB(skb)->keypair;
+		free = true;
+
+		if (unlikely(state != PACKET_STATE_CRYPTED))
+			goto next;
+
+		if (unlikely(!counter_validate(&keypair->receiving.counter,
+					       PACKET_CB(skb)->nonce))) {
+			net_dbg_ratelimited("%s: Packet has invalid nonce %llu (max %llu)\n",
+					    peer->device->dev->name,
+					    PACKET_CB(skb)->nonce,
+					    keypair->receiving.counter.receive.counter);
+			goto next;
+		}
+
+		if (unlikely(wg_socket_endpoint_from_skb(&endpoint, skb)))
+			goto next;
+
+		wg_reset_packet(skb);
+		wg_packet_consume_data_done(peer, skb, &endpoint);
+		free = false;
+
+next:
+		wg_noise_keypair_put(keypair, false);
+		wg_peer_put(peer);
+		if (unlikely(free))
+			dev_kfree_skb(skb);
+
+		if (++work_done >= budget)
+			break;
+	}
+
+	if (work_done < budget)
+		napi_complete_done(napi, work_done);
+
+	return work_done;
+}
+
+void wg_packet_decrypt_worker(struct work_struct *work)
+{
+	struct crypt_queue *queue = container_of(work, struct multicore_worker,
+						 work)->ptr;
+	struct sk_buff *skb;
+
+	while ((skb = ptr_ring_consume_bh(&queue->ring)) != NULL) {
+		enum packet_state state = likely(decrypt_packet(skb,
+				&PACKET_CB(skb)->keypair->receiving)) ?
+				PACKET_STATE_CRYPTED : PACKET_STATE_DEAD;
+		wg_queue_enqueue_per_peer_napi(skb, state);
+	}
+}
+
+static void wg_packet_consume_data(struct wg_device *wg, struct sk_buff *skb)
+{
+	__le32 idx = ((struct message_data *)skb->data)->key_idx;
+	struct wg_peer *peer = NULL;
+	int ret;
+
+	rcu_read_lock_bh();
+	PACKET_CB(skb)->keypair =
+		(struct noise_keypair *)wg_index_hashtable_lookup(
+			wg->index_hashtable, INDEX_HASHTABLE_KEYPAIR, idx,
+			&peer);
+	if (unlikely(!wg_noise_keypair_get(PACKET_CB(skb)->keypair)))
+		goto err_keypair;
+
+	if (unlikely(READ_ONCE(peer->is_dead)))
+		goto err;
+
+	ret = wg_queue_enqueue_per_device_and_peer(&wg->decrypt_queue,
+						   &peer->rx_queue, skb,
+						   wg->packet_crypt_wq,
+						   &wg->decrypt_queue.last_cpu);
+	if (unlikely(ret == -EPIPE))
+		wg_queue_enqueue_per_peer_napi(skb, PACKET_STATE_DEAD);
+	if (likely(!ret || ret == -EPIPE)) {
+		rcu_read_unlock_bh();
+		return;
+	}
+err:
+	wg_noise_keypair_put(PACKET_CB(skb)->keypair, false);
+err_keypair:
+	rcu_read_unlock_bh();
+	wg_peer_put(peer);
+	dev_kfree_skb(skb);
+}
+
+void wg_packet_receive(struct wg_device *wg, struct sk_buff *skb)
+{
+	if (unlikely(prepare_skb_header(skb, wg) < 0))
+		goto err;
+	switch (SKB_TYPE_LE32(skb)) {
+	case cpu_to_le32(MESSAGE_HANDSHAKE_INITIATION):
+	case cpu_to_le32(MESSAGE_HANDSHAKE_RESPONSE):
+	case cpu_to_le32(MESSAGE_HANDSHAKE_COOKIE): {
+		int cpu;
+
+		if (skb_queue_len(&wg->incoming_handshakes) >
+			    MAX_QUEUED_INCOMING_HANDSHAKES ||
+		    unlikely(!rng_is_initialized())) {
+			net_dbg_skb_ratelimited("%s: Dropping handshake packet from %pISpfsc\n",
+						wg->dev->name, skb);
+			goto err;
+		}
+		skb_queue_tail(&wg->incoming_handshakes, skb);
+		/* Queues up a call to packet_process_queued_handshake_
+		 * packets(skb):
+		 */
+		cpu = wg_cpumask_next_online(&wg->incoming_handshake_cpu);
+		queue_work_on(cpu, wg->handshake_receive_wq,
+			&per_cpu_ptr(wg->incoming_handshakes_worker, cpu)->work);
+		break;
+	}
+	case cpu_to_le32(MESSAGE_DATA):
+		PACKET_CB(skb)->ds = ip_tunnel_get_dsfield(ip_hdr(skb), skb);
+		wg_packet_consume_data(wg, skb);
+		break;
+	default:
+		net_dbg_skb_ratelimited("%s: Invalid packet from %pISpfsc\n",
+					wg->dev->name, skb);
+		goto err;
+	}
+	return;
+
+err:
+	dev_kfree_skb(skb);
+}