From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:27:49 +0200 Subject: Adding upstream version 6.6.15. Signed-off-by: Daniel Baumann --- drivers/net/wireguard/receive.c | 586 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 586 insertions(+) create mode 100644 drivers/net/wireguard/receive.c (limited to 'drivers/net/wireguard/receive.c') diff --git a/drivers/net/wireguard/receive.c b/drivers/net/wireguard/receive.c new file mode 100644 index 0000000000..a176653c88 --- /dev/null +++ b/drivers/net/wireguard/receive.c @@ -0,0 +1,586 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2015-2019 Jason A. Donenfeld . 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 +#include +#include +#include + +/* Must be called with bh disabled. */ +static void update_rx_stats(struct wg_peer *peer, size_t len) +{ + dev_sw_netstats_rx_add(peer->device->dev, len); + peer->rx_bytes += len; +} + +#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_check_packet_protocol(skb) || + 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 = atomic_read(&wg->handshake_queue_len) >= + 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); + if (!under_load) + last_under_load = 0; + } + 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 crypt_queue *queue = container_of(work, struct multicore_worker, work)->ptr; + struct wg_device *wg = container_of(queue, struct wg_device, handshake_queue); + struct sk_buff *skb; + + while ((skb = ptr_ring_consume_bh(&queue->ring)) != NULL) { + wg_receive_handshake_packet(wg, skb); + dev_kfree_skb(skb); + atomic_dec(&wg->handshake_queue_len); + cond_resched(); + } +} + +static void keep_key_fresh(struct wg_peer *peer) +{ + struct noise_keypair *keypair; + bool send; + + if (peer->sent_lastminute_handshake) + return; + + rcu_read_lock_bh(); + keypair = rcu_dereference_bh(peer->keypairs.current_keypair); + send = keypair && READ_ONCE(keypair->sending.is_valid) && + keypair->i_am_the_initiator && + wg_birthdate_has_expired(keypair->sending.birthdate, + REJECT_AFTER_TIME - KEEPALIVE_TIMEOUT - REKEY_TIMEOUT); + rcu_read_unlock_bh(); + + if (unlikely(send)) { + peer->sent_lastminute_handshake = true; + wg_packet_send_queued_handshake_initiation(peer, false); + } +} + +static bool decrypt_packet(struct sk_buff *skb, struct noise_keypair *keypair) +{ + struct scatterlist sg[MAX_SKB_FRAGS + 8]; + struct sk_buff *trailer; + unsigned int offset; + int num_frags; + + if (unlikely(!keypair)) + return false; + + if (unlikely(!READ_ONCE(keypair->receiving.is_valid) || + wg_birthdate_has_expired(keypair->receiving.birthdate, REJECT_AFTER_TIME) || + keypair->receiving_counter.counter >= REJECT_AFTER_MESSAGES)) { + WRITE_ONCE(keypair->receiving.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, + keypair->receiving.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(struct noise_replay_counter *counter, u64 their_counter) +{ + unsigned long index, index_current, top, i; + bool ret = false; + + spin_lock_bh(&counter->lock); + + if (unlikely(counter->counter >= REJECT_AFTER_MESSAGES + 1 || + their_counter >= REJECT_AFTER_MESSAGES)) + goto out; + + ++their_counter; + + if (unlikely((COUNTER_WINDOW_SIZE + their_counter) < + counter->counter)) + goto out; + + index = their_counter >> ilog2(BITS_PER_LONG); + + if (likely(their_counter > counter->counter)) { + index_current = counter->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->backtrack[(i + index_current) & + ((COUNTER_BITS_TOTAL / BITS_PER_LONG) - 1)] = 0; + counter->counter = their_counter; + } + + index &= (COUNTER_BITS_TOTAL / BITS_PER_LONG) - 1; + ret = !test_and_set_bit(their_counter & (BITS_PER_LONG - 1), + &counter->backtrack[index]); + +out: + spin_unlock_bh(&counter->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 unnecessary to check + * again in software. + */ + skb->ip_summed = CHECKSUM_UNNECESSARY; + skb->csum_level = ~0; /* All levels */ + skb->protocol = ip_tunnel_parse_protocol(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; + INET_ECN_decapsulate(skb, PACKET_CB(skb)->ds, ip_hdr(skb)->tos); + } else if (skb->protocol == htons(ETH_P_IPV6)) { + len = ntohs(ipv6_hdr(skb)->payload_len) + + sizeof(struct ipv6hdr); + INET_ECN_decapsulate(skb, PACKET_CB(skb)->ds, ipv6_get_dsfield(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; + + napi_gro_receive(&peer->napi, skb); + 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_INC(dev, rx_errors); + DEV_STATS_INC(dev, 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_INC(dev, rx_errors); + DEV_STATS_INC(dev, 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_INC(dev, rx_errors); + DEV_STATS_INC(dev, 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 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 = wg_prev_queue_peek(&peer->rx_queue)) != NULL && + (state = atomic_read_acquire(&PACKET_CB(skb)->state)) != + PACKET_STATE_UNCRYPTED) { + wg_prev_queue_drop_peeked(&peer->rx_queue); + 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.counter); + goto next; + } + + if (unlikely(wg_socket_endpoint_from_skb(&endpoint, skb))) + goto next; + + wg_reset_packet(skb, false); + 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)) ? + PACKET_STATE_CRYPTED : PACKET_STATE_DEAD; + wg_queue_enqueue_per_peer_rx(skb, state); + if (need_resched()) + cond_resched(); + } +} + +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); + if (unlikely(ret == -EPIPE)) + wg_queue_enqueue_per_peer_rx(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, ret = -EBUSY; + + if (unlikely(!rng_is_initialized())) + goto drop; + if (atomic_read(&wg->handshake_queue_len) > MAX_QUEUED_INCOMING_HANDSHAKES / 2) { + if (spin_trylock_bh(&wg->handshake_queue.ring.producer_lock)) { + ret = __ptr_ring_produce(&wg->handshake_queue.ring, skb); + spin_unlock_bh(&wg->handshake_queue.ring.producer_lock); + } + } else + ret = ptr_ring_produce_bh(&wg->handshake_queue.ring, skb); + if (ret) { + drop: + net_dbg_skb_ratelimited("%s: Dropping handshake packet from %pISpfsc\n", + wg->dev->name, skb); + goto err; + } + atomic_inc(&wg->handshake_queue_len); + cpu = wg_cpumask_next_online(&wg->handshake_queue.last_cpu); + /* Queues up a call to packet_process_queued_handshake_packets(skb): */ + queue_work_on(cpu, wg->handshake_receive_wq, + &per_cpu_ptr(wg->handshake_queue.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: + WARN(1, "Non-exhaustive parsing of packet header lead to unknown packet type!\n"); + goto err; + } + return; + +err: + dev_kfree_skb(skb); +} -- cgit v1.2.3