path: root/src/plugins/wireguard/wireguard_input.c

/*
 * Copyright (c) 2020 Doc.ai and/or its affiliates.
 * Copyright (c) 2020 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <vlib/vlib.h>
#include <vnet/vnet.h>
#include <vppinfra/error.h>
#include <wireguard/wireguard.h>

#include <wireguard/wireguard_send.h>
#include <wireguard/wireguard_if.h>

#define foreach_wg_input_error                                                \
  _ (NONE, "No error")                                                        \
  _ (HANDSHAKE_MAC, "Invalid MAC handshake")                                  \
  _ (PEER, "Peer error")                                                      \
  _ (INTERFACE, "Interface error")                                            \
  _ (DECRYPTION, "Failed during decryption")                                  \
  _ (KEEPALIVE_SEND, "Failed while sending Keepalive")                        \
  _ (HANDSHAKE_SEND, "Failed while sending Handshake")                        \
  _ (HANDSHAKE_RECEIVE, "Failed while receiving Handshake")                   \
  _ (TOO_BIG, "Packet too big")                                               \
  _ (UNDEFINED, "Undefined error")

typedef enum
{
#define _(sym,str) WG_INPUT_ERROR_##sym,
  foreach_wg_input_error
#undef _
    WG_INPUT_N_ERROR,
} wg_input_error_t;

static char *wg_input_error_strings[] = {
#define _(sym,string) string,
  foreach_wg_input_error
#undef _
};

typedef struct
{
  message_type_t type;
  u16 current_length;
  bool is_keepalive;
  index_t peer;
} wg_input_trace_t;

u8 *
format_wg_message_type (u8 * s, va_list * args)
{
  message_type_t type = va_arg (*args, message_type_t);

  switch (type)
    {
#define _(v,a) case MESSAGE_##v: return (format (s, "%s", a));
      foreach_wg_message_type
#undef _
    }
  return (format (s, "unknown"));
}

/* packet trace format function */
static u8 *
format_wg_input_trace (u8 * s, va_list * args)
{
  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);

  wg_input_trace_t *t = va_arg (*args, wg_input_trace_t *);

  s = format (s, "Wireguard input: \n");
  s = format (s, "    Type: %U\n", format_wg_message_type, t->type);
  s = format (s, "    Peer: %d\n", t->peer);
  s = format (s, "    Length: %d\n", t->current_length);
  s = format (s, "    Keepalive: %s", t->is_keepalive ? "true" : "false");

  return s;
}

typedef enum
{
  WG_INPUT_NEXT_HANDOFF_HANDSHAKE,
  WG_INPUT_NEXT_HANDOFF_DATA,
  WG_INPUT_NEXT_IP4_INPUT,
  WG_INPUT_NEXT_IP6_INPUT,
  WG_INPUT_NEXT_PUNT,
  WG_INPUT_NEXT_ERROR,
  WG_INPUT_N_NEXT,
} wg_input_next_t;

/* static void */
/* set_peer_address (wg_peer_t * peer, ip4_address_t ip4, u16 udp_port) */
/* { */
/*   if (peer) */
/*     { */
/*       ip46_address_set_ip4 (&peer->dst.addr, &ip4); */
/*       peer->dst.port = udp_port; */
/*     } */
/* } */

static u8
is_ip4_header (u8 *data)
{
  return (data[0] >> 4) == 0x4;
}

static wg_input_error_t
wg_handshake_process (vlib_main_t *vm, wg_main_t *wmp, vlib_buffer_t *b,
		      u32 node_idx, u8 is_ip4)
{
  ASSERT (vm->thread_index == 0);

  enum cookie_mac_state mac_state;
  bool packet_needs_cookie;
  bool under_load;
  index_t *wg_ifs;
  wg_if_t *wg_if;
  wg_peer_t *peer = NULL;

  void *current_b_data = vlib_buffer_get_current (b);

  ip46_address_t src_ip;
  if (is_ip4)
    {
      ip4_header_t *iph4 =
	current_b_data - sizeof (udp_header_t) - sizeof (ip4_header_t);
      ip46_address_set_ip4 (&src_ip, &iph4->src_address);
    }
  else
    {
      ip6_header_t *iph6 =
	current_b_data - sizeof (udp_header_t) - sizeof (ip6_header_t);
      ip46_address_set_ip6 (&src_ip, &iph6->src_address);
    }

  udp_header_t *uhd = current_b_data - sizeof (udp_header_t);
  u16 udp_src_port = clib_host_to_net_u16 (uhd->src_port);;
  u16 udp_dst_port = clib_host_to_net_u16 (uhd->dst_port);;

  message_header_t *header = current_b_data;
  under_load = false;

  if (PREDICT_FALSE (header->type == MESSAGE_HANDSHAKE_COOKIE))
    {
      message_handshake_cookie_t *packet =
	(message_handshake_cookie_t *) current_b_data;
      u32 *entry =
	wg_index_table_lookup (&wmp->index_table, packet->receiver_index);
      if (entry)
	peer = wg_peer_get (*entry);
      else
	return WG_INPUT_ERROR_PEER;

      // TODO: Implement cookie_maker_consume_payload

      return WG_INPUT_ERROR_NONE;
    }

  u32 len = (header->type == MESSAGE_HANDSHAKE_INITIATION ?
	     sizeof (message_handshake_initiation_t) :
	     sizeof (message_handshake_response_t));

  message_macs_t *macs = (message_macs_t *)
    ((u8 *) current_b_data + len - sizeof (*macs));

  index_t *ii;
  wg_ifs = wg_if_indexes_get_by_port (udp_dst_port);
  if (NULL == wg_ifs)
    return WG_INPUT_ERROR_INTERFACE;

  vec_foreach (ii, wg_ifs)
    {
      wg_if = wg_if_get (*ii);
      if (NULL == wg_if)
	continue;

      mac_state = cookie_checker_validate_macs (
	vm, &wg_if->cookie_checker, macs, current_b_data, len, under_load,
	&src_ip, udp_src_port);
      if (mac_state == INVALID_MAC)
	{
	  wg_if = NULL;
	  continue;
	}
      break;
    }

  if (NULL == wg_if)
    return WG_INPUT_ERROR_HANDSHAKE_MAC;

  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
    return WG_INPUT_ERROR_HANDSHAKE_MAC;

  switch (header->type)
    {
    case MESSAGE_HANDSHAKE_INITIATION:
      {
	message_handshake_initiation_t *message = current_b_data;

	if (packet_needs_cookie)
	  {
	    // TODO: Add processing
	  }
	noise_remote_t *rp;
	if (noise_consume_initiation
	    (vm, noise_local_get (wg_if->local_idx), &rp,
	     message->sender_index, message->unencrypted_ephemeral,
	     message->encrypted_static, message->encrypted_timestamp))
	  {
	    peer = wg_peer_get (rp->r_peer_idx);
	  }
	else
	  {
	    return WG_INPUT_ERROR_PEER;
	  }

	// set_peer_address (peer, ip4_src, udp_src_port);
	if (PREDICT_FALSE (!wg_send_handshake_response (vm, peer)))
	  {
	    vlib_node_increment_counter (vm, node_idx,
					 WG_INPUT_ERROR_HANDSHAKE_SEND, 1);
	  }
	else
	  {
	    wg_peer_update_flags (rp->r_peer_idx, WG_PEER_ESTABLISHED, true);
	  }
	break;
      }
    case MESSAGE_HANDSHAKE_RESPONSE:
      {
	message_handshake_response_t *resp = current_b_data;
	index_t peeri = INDEX_INVALID;
	u32 *entry =
	  wg_index_table_lookup (&wmp->index_table, resp->receiver_index);

	if (PREDICT_TRUE (entry != NULL))
	  {
	    peeri = *entry;
	    peer = wg_peer_get (peeri);
	    if (wg_peer_is_dead (peer))
	      return WG_INPUT_ERROR_PEER;
	  }
	else
	  return WG_INPUT_ERROR_PEER;

	if (!noise_consume_response
	    (vm, &peer->remote, resp->sender_index,
	     resp->receiver_index, resp->unencrypted_ephemeral,
	     resp->encrypted_nothing))
	  {
	    return WG_INPUT_ERROR_PEER;
	  }
	if (packet_needs_cookie)
	  {
	    // TODO: Add processing
	  }

	// set_peer_address (peer, ip4_src, udp_src_port);
	if (noise_remote_begin_session (vm, &peer->remote))
	  {

	    wg_timers_session_derived (peer);
	    wg_timers_handshake_complete (peer);
	    if (PREDICT_FALSE (!wg_send_keepalive (vm, peer)))
	      {
		vlib_node_increment_counter (vm, node_idx,
					     WG_INPUT_ERROR_KEEPALIVE_SEND, 1);
	      }
	    else
	      {
		wg_peer_update_flags (peeri, WG_PEER_ESTABLISHED, true);
	      }
	  }
	break;
      }
    default:
      return WG_INPUT_ERROR_HANDSHAKE_RECEIVE;
    }

  wg_timers_any_authenticated_packet_received (peer);
  wg_timers_any_authenticated_packet_traversal (peer);
  return WG_INPUT_ERROR_NONE;
}

always_inline uword
wg_input_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
		 vlib_frame_t *frame, u8 is_ip4)
{
  message_type_t header_type;
  u32 n_left_from;
  u32 *from;
  vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
  u16 nexts[VLIB_FRAME_SIZE], *next;
  u32 thread_index = vm->thread_index;

  from = vlib_frame_vector_args (frame);
  n_left_from = frame->n_vectors;
  b = bufs;
  next = nexts;

  vlib_get_buffers (vm, from, bufs, n_left_from);

  wg_main_t *wmp = &wg_main;
  wg_peer_t *peer = NULL;

  while (n_left_from > 0)
    {
      bool is_keepalive = false;
      next[0] = WG_INPUT_NEXT_PUNT;
      header_type =
	((message_header_t *) vlib_buffer_get_current (b[0]))->type;
      u32 *peer_idx;

      if (PREDICT_TRUE (header_type == MESSAGE_DATA))
	{
	  message_data_t *data = vlib_buffer_get_current (b[0]);

	  peer_idx = wg_index_table_lookup (&wmp->index_table,
					    data->receiver_index);

	  if (peer_idx)
	    {
	      peer = wg_peer_get (*peer_idx);
	    }
	  else
	    {
	      next[0] = WG_INPUT_NEXT_ERROR;
	      b[0]->error = node->errors[WG_INPUT_ERROR_PEER];
	      goto out;
	    }

	  if (PREDICT_FALSE (~0 == peer->input_thread_index))
	    {
	      /* this is the first packet to use this peer, claim the peer
	       * for this thread.
	       */
	      clib_atomic_cmp_and_swap (&peer->input_thread_index, ~0,
					wg_peer_assign_thread (thread_index));
	    }

	  if (PREDICT_TRUE (thread_index != peer->input_thread_index))
	    {
	      next[0] = WG_INPUT_NEXT_HANDOFF_DATA;
	      goto next;
	    }

	  u16 encr_len = b[0]->current_length - sizeof (message_data_t);
	  u16 decr_len = encr_len - NOISE_AUTHTAG_LEN;
	  if (PREDICT_FALSE (decr_len >= WG_DEFAULT_DATA_SIZE))
	    {
	      b[0]->error = node->errors[WG_INPUT_ERROR_TOO_BIG];
	      goto out;
	    }

	  enum noise_state_crypt state_cr = noise_remote_decrypt (
	    vm, &peer->remote, data->receiver_index, data->counter,
	    data->encrypted_data, encr_len, data->encrypted_data);

	  if (PREDICT_FALSE (state_cr == SC_CONN_RESET))
	    {
	      wg_timers_handshake_complete (peer);
	    }
	  else if (PREDICT_FALSE (state_cr == SC_KEEP_KEY_FRESH))
	    {
	      wg_send_handshake_from_mt (*peer_idx, false);
	    }
	  else if (PREDICT_FALSE (state_cr == SC_FAILED))
	    {
	      wg_peer_update_flags (*peer_idx, WG_PEER_ESTABLISHED, false);
	      next[0] = WG_INPUT_NEXT_ERROR;
	      b[0]->error = node->errors[WG_INPUT_ERROR_DECRYPTION];
	      goto out;
	    }

	  vlib_buffer_advance (b[0], sizeof (message_data_t));
	  b[0]->current_length = decr_len;
	  vnet_buffer_offload_flags_clear (b[0],
					   VNET_BUFFER_OFFLOAD_F_UDP_CKSUM);

	  wg_timers_any_authenticated_packet_received (peer);
	  wg_timers_any_authenticated_packet_traversal (peer);

	  /* Keepalive packet has zero length */
	  if (decr_len == 0)
	    {
	      is_keepalive = true;
	      goto out;
	    }

	  wg_timers_data_received (peer);

	  ip46_address_t src_ip;
	  u8 is_ip4_inner = is_ip4_header (vlib_buffer_get_current (b[0]));
	  if (is_ip4_inner)
	    {
	      ip46_address_set_ip4 (
		&src_ip, &((ip4_header_t *) vlib_buffer_get_current (b[0]))
			    ->src_address);
	    }
	  else
	    {
	      ip46_address_set_ip6 (
		&src_ip, &((ip6_header_t *) vlib_buffer_get_current (b[0]))
			    ->src_address);
	    }

	  const fib_prefix_t *allowed_ip;
	  bool allowed = false;

	  /*
	   * we could make this into an ACL, but the expectation
	   * is that there aren't many allowed IPs and thus a linear
	   * walk is fater than an ACL
	   */

	  vec_foreach (allowed_ip, peer->allowed_ips)
	  {
	    if (fib_prefix_is_cover_addr_46 (allowed_ip, &src_ip))
	      {
		allowed = true;
		break;
	      }
	  }
	  if (allowed)
	    {
	      vnet_buffer (b[0])->sw_if_index[VLIB_RX] = peer->wg_sw_if_index;
	      next[0] = is_ip4_inner ? WG_INPUT_NEXT_IP4_INPUT :
				       WG_INPUT_NEXT_IP6_INPUT;
	    }
	}
      else
	{
	  peer_idx = NULL;

	  /* Handshake packets should be processed in main thread */
	  if (thread_index != 0)
	    {
	      next[0] = WG_INPUT_NEXT_HANDOFF_HANDSHAKE;
	      goto next;
	    }

	  wg_input_error_t ret =
	    wg_handshake_process (vm, wmp, b[0], node->node_index, is_ip4);
	  if (ret != WG_INPUT_ERROR_NONE)
	    {
	      next[0] = WG_INPUT_NEXT_ERROR;
	      b[0]->error = node->errors[ret];
	    }
	}

    out:
      if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
			 && (b[0]->flags & VLIB_BUFFER_IS_TRACED)))
	{
	  wg_input_trace_t *t = vlib_add_trace (vm, node, b[0], sizeof (*t));
	  t->type = header_type;
	  t->current_length = b[0]->current_length;
	  t->is_keepalive = is_keepalive;
	  t->peer = peer_idx ? *peer_idx : INDEX_INVALID;
	}
    next:
      n_left_from -= 1;
      next += 1;
      b += 1;
    }
  vlib_buffer_enqueue_to_next (vm, node, from, nexts, frame->n_vectors);

  return frame->n_vectors;
}

VLIB_NODE_FN (wg4_input_node)
(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
  return wg_input_inline (vm, node, frame, /* is_ip4 */ 1);
}

VLIB_NODE_FN (wg6_input_node)
(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
  return wg_input_inline (vm, node, frame, /* is_ip4 */ 0);
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (wg4_input_node) =
{
  .name = "wg4-input",
  .vector_size = sizeof (u32),
  .format_trace = format_wg_input_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN (wg_input_error_strings),
  .error_strings = wg_input_error_strings,
  .n_next_nodes = WG_INPUT_N_NEXT,
  /* edit / add dispositions here */
  .next_nodes = {
        [WG_INPUT_NEXT_HANDOFF_HANDSHAKE] = "wg4-handshake-handoff",
        [WG_INPUT_NEXT_HANDOFF_DATA] = "wg4-input-data-handoff",
        [WG_INPUT_NEXT_IP4_INPUT] = "ip4-input-no-checksum",
        [WG_INPUT_NEXT_IP6_INPUT] = "ip6-input",
        [WG_INPUT_NEXT_PUNT] = "error-punt",
        [WG_INPUT_NEXT_ERROR] = "error-drop",
  },
};

VLIB_REGISTER_NODE (wg6_input_node) =
{
  .name = "wg6-input",
  .vector_size = sizeof (u32),
  .format_trace = format_wg_input_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN (wg_input_error_strings),
  .error_strings = wg_input_error_strings,
  .n_next_nodes = WG_INPUT_N_NEXT,
  /* edit / add dispositions here */
  .next_nodes = {
        [WG_INPUT_NEXT_HANDOFF_HANDSHAKE] = "wg6-handshake-handoff",
        [WG_INPUT_NEXT_HANDOFF_DATA] = "wg6-input-data-handoff",
        [WG_INPUT_NEXT_IP4_INPUT] = "ip4-input-no-checksum",
        [WG_INPUT_NEXT_IP6_INPUT] = "ip6-input",
        [WG_INPUT_NEXT_PUNT] = "error-punt",
        [WG_INPUT_NEXT_ERROR] = "error-drop",
  },
};
/* *INDENT-ON* */

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */