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path: root/drivers/net/wireguard/receive.c
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Diffstat (limited to 'drivers/net/wireguard/receive.c')
-rw-r--r--drivers/net/wireguard/receive.c604
1 files changed, 604 insertions, 0 deletions
diff --git a/drivers/net/wireguard/receive.c b/drivers/net/wireguard/receive.c
new file mode 100644
index 000000000000..900c76edb9d6
--- /dev/null
+++ b/drivers/net/wireguard/receive.c
@@ -0,0 +1,604 @@
+// 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/simd.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_boot_fast_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,
+ simd_context_t *simd_context)
+{
+ 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(sg, sg, skb->len, NULL, 0,
+ PACKET_CB(skb)->nonce, key->key,
+ simd_context))
+ 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;
+ simd_context_t simd_context;
+ struct sk_buff *skb;
+
+ simd_get(&simd_context);
+ while ((skb = ptr_ring_consume_bh(&queue->ring)) != NULL) {
+ enum packet_state state = likely(decrypt_packet(skb,
+ &PACKET_CB(skb)->keypair->receiving,
+ &simd_context)) ?
+ PACKET_STATE_CRYPTED : PACKET_STATE_DEAD;
+ wg_queue_enqueue_per_peer_napi(&PACKET_PEER(skb)->rx_queue, skb,
+ state);
+ simd_relax(&simd_context);
+ }
+
+ simd_put(&simd_context);
+}
+
+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(&peer->rx_queue, 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);
+}