text: /*
   * ah_decrypt.c : IPSec AH decrypt node
   *
   * Copyright (c) 2015 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 <vnet/vnet.h>
  #include <vnet/api_errno.h>
  #include <vnet/ip/ip.h>
  
  #include <vnet/ipsec/ipsec.h>
  #include <vnet/ipsec/esp.h>
  #include <vnet/ipsec/ah.h>
  #include <vnet/ipsec/ipsec_io.h>
  
  #define foreach_ah_decrypt_next                 \
    _(DROP, "error-drop")                         \
    _(IP4_INPUT, "ip4-input")                     \
    _(IP6_INPUT, "ip6-input")                     \
    _(HANDOFF, "handoff")
  
  #define _(v, s) AH_DECRYPT_NEXT_##v,
  typedef enum
  {
    foreach_ah_decrypt_next
  #undef _
      AH_DECRYPT_N_NEXT,
  } ah_decrypt_next_t;
  
  #define foreach_ah_decrypt_error                \
    _ (RX_PKTS, "AH pkts received")               \
    _ (DECRYPTION_FAILED, "AH decryption failed") \
    _ (INTEG_ERROR, "Integrity check failed")     \
    _ (NO_TAIL_SPACE, "not enough buffer tail space (dropped)")     \
    _ (DROP_FRAGMENTS, "IP fragments drop")       \
    _ (REPLAY, "SA replayed packet")
  
  typedef enum
  {
  #define _(sym,str) AH_DECRYPT_ERROR_##sym,
    foreach_ah_decrypt_error
  #undef _
      AH_DECRYPT_N_ERROR,
  } ah_decrypt_error_t;
  
  static char *ah_decrypt_error_strings[] = {
  #define _(sym,string) string,
    foreach_ah_decrypt_error
  #undef _
  };
  
  typedef struct
  {
    ipsec_integ_alg_t integ_alg;
    u32 seq_num;
  } ah_decrypt_trace_t;
  
  /* packet trace format function */
  static u8 *
  format_ah_decrypt_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 *);
    ah_decrypt_trace_t *t = va_arg (*args, ah_decrypt_trace_t *);
  
    s = format (s, "ah: integrity %U seq-num %d",
  	      format_ipsec_integ_alg, t->integ_alg, t->seq_num);
    return s;
  }
  
  typedef struct
  {
    union
    {
      struct
      {
        u8 hop_limit;
        u8 nexthdr;
        u32 ip_version_traffic_class_and_flow_label;
      };
  
      struct
      {
        u8 ttl;
        u8 tos;
      };
    };
    u32 sa_index;
    u32 seq;
    u8 icv_padding_len;
    u8 icv_size;
    u8 ip_hdr_size;
    i16 current_data;
    u8 nexthdr_cached;
  } ah_decrypt_packet_data_t;
  
  static_always_inline void
  ah_process_ops (vlib_main_t * vm, vlib_node_runtime_t * node,
  		vnet_crypto_op_t * ops, vlib_buffer_t * b[], u16 * nexts)
  {
    u32 n_fail, n_ops = vec_len (ops);
    vnet_crypto_op_t *op = ops;
  
    if (n_ops == 0)
      return;
  
    n_fail = n_ops - vnet_crypto_process_ops (vm, op, n_ops);
  
    while (n_fail)
      {
        ASSERT (op - ops < n_ops);
  
        if (op->status != VNET_CRYPTO_OP_STATUS_COMPLETED)
  	{
  	  u32 bi = op->user_data;
  	  b[bi]->error = node->errors[AH_DECRYPT_ERROR_INTEG_ERROR];
  	  nexts[bi] = AH_DECRYPT_NEXT_DROP;
  	  n_fail--;
  	}
        op++;
      }
  }
  
  always_inline uword
  ah_decrypt_inline (vlib_main_t * vm,
  		   vlib_node_runtime_t * node, vlib_frame_t * from_frame,
  		   int is_ip6)
  {
    u32 n_left, *from;
    u32 thread_index = vm->thread_index;
    u16 buffer_data_size = vlib_buffer_get_default_data_size (vm);
    ah_decrypt_packet_data_t pkt_data[VLIB_FRAME_SIZE], *pd = pkt_data;
    vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b = bufs;
    u16 nexts[VLIB_FRAME_SIZE], *next = nexts;
    ipsec_main_t *im = &ipsec_main;
    ipsec_per_thread_data_t *ptd = vec_elt_at_index (im->ptd, thread_index);
    from = vlib_frame_vector_args (from_frame);
    n_left = from_frame->n_vectors;
    ipsec_sa_t *sa0 = 0;
    u32 current_sa_index = ~0, current_sa_bytes = 0, current_sa_pkts = 0;
  
    clib_memset (pkt_data, 0, VLIB_FRAME_SIZE * sizeof (pkt_data[0]));
    vlib_get_buffers (vm, from, b, n_left);
    clib_memset_u16 (nexts, -1, n_left);
    vec_reset_length (ptd->integ_ops);
  
    while (n_left > 0)
      {
        ah_header_t *ah0;
        ip4_header_t *ih4;
        ip6_header_t *ih6;
  
        if (vnet_buffer (b[0])->ipsec.sad_index != current_sa_index)
  	{
  	  if (current_sa_index != ~0)
  	    vlib_increment_combined_counter (&ipsec_sa_counters, thread_index,
  					     current_sa_index,
  					     current_sa_pkts,
  					     current_sa_bytes);
  	  current_sa_index = vnet_buffer (b[0])->ipsec.sad_index;
  	  sa0 = ipsec_sa_get (current_sa_index);
  
  	  current_sa_bytes = current_sa_pkts = 0;
  	  vlib_prefetch_combined_counter (&ipsec_sa_counters,
  					  thread_index, current_sa_index);
  	}
  
        if (PREDICT_FALSE (~0 == sa0->thread_index))
  	{
  	  /* this is the first packet to use this SA, claim the SA
  	   * for this thread. this could happen simultaneously on
  	   * another thread */
  	  clib_atomic_cmp_and_swap (&sa0->thread_index, ~0,
  				    ipsec_sa_assign_thread (thread_index));
  	}
  
        if (PREDICT_TRUE (thread_index != sa0->thread_index))
  	{
  	  vnet_buffer (b[0])->ipsec.thread_index = sa0->thread_index;
  	  next[0] = AH_DECRYPT_NEXT_HANDOFF;
  	  goto next;
  	}
  
        pd->sa_index = current_sa_index;
  
        ih4 = vlib_buffer_get_current (b[0]);
        ih6 = vlib_buffer_get_current (b[0]);
        pd->current_data = b[0]->current_data;
  
        if (is_ip6)
  	{
  	  ip6_ext_header_t *prev = NULL;
  	  ah0 =
  	    ip6_ext_header_find (vm, b[0], ih6, IP_PROTOCOL_IPSEC_AH, &prev);
  	  pd->ip_hdr_size = sizeof (ip6_header_t);
  	  ASSERT ((u8 *) ah0 - (u8 *) ih6 == pd->ip_hdr_size);
  	}
        else
  	{
  	  if (ip4_is_fragment (ih4))
  	    {
  	      b[0]->error = node->errors[AH_DECRYPT_ERROR_DROP_FRAGMENTS];
  	      next[0] = AH_DECRYPT_NEXT_DROP;
  	      goto next;
  	    }
  	  pd->ip_hdr_size = ip4_header_bytes (ih4);
  	  ah0 = (ah_header_t *) ((u8 *) ih4 + pd->ip_hdr_size);
  	}
  
        pd->seq = clib_host_to_net_u32 (ah0->seq_no);
  
        /* anti-replay check */
        if (ipsec_sa_anti_replay_check (sa0, pd->seq))
  	{
  	  b[0]->error = node->errors[AH_DECRYPT_ERROR_REPLAY];
  	  next[0] = AH_DECRYPT_NEXT_DROP;
  	  goto next;
  	}
  
        current_sa_bytes += b[0]->current_length;
        current_sa_pkts += 1;
  
        pd->icv_size = sa0->integ_icv_size;
        pd->nexthdr_cached = ah0->nexthdr;
        if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
  	{
  	  if (PREDICT_FALSE (ipsec_sa_is_set_USE_ESN (sa0) &&
  			     pd->current_data + b[0]->current_length
  			     + sizeof (u32) > buffer_data_size))
  	    {
  	      b[0]->error = node->errors[AH_DECRYPT_ERROR_NO_TAIL_SPACE];
  	      next[0] = AH_DECRYPT_NEXT_DROP;
  	      goto next;
  	    }
  
  	  vnet_crypto_op_t *op;
  	  vec_add2_aligned (ptd->integ_ops, op, 1, CLIB_CACHE_LINE_BYTES);
  	  vnet_crypto_op_init (op, sa0->integ_op_id);
  
  	  op->src = (u8 *) ih4;
  	  op->len = b[0]->current_length;
  	  op->digest = (u8 *) ih4 - pd->icv_size;
  	  op->flags = VNET_CRYPTO_OP_FLAG_HMAC_CHECK;
  	  op->digest_len = pd->icv_size;
  	  op->key_index = sa0->integ_key_index;
  	  op->user_data = b - bufs;
  	  if (ipsec_sa_is_set_USE_ESN (sa0))
  	    {
  	      u32 seq_hi = clib_host_to_net_u32 (sa0->seq_hi);
  
  	      op->len += sizeof (seq_hi);
  	      clib_memcpy (op->src + b[0]->current_length, &seq_hi,
  			   sizeof (seq_hi));
  	    }
  	  clib_memcpy (op->digest, ah0->auth_data, pd->icv_size);
  	  clib_memset (ah0->auth_data, 0, pd->icv_size);
  
  	  if (is_ip6)
  	    {
  	      pd->ip_version_traffic_class_and_flow_label =
  		ih6->ip_version_traffic_class_and_flow_label;
  	      pd->hop_limit = ih6->hop_limit;
  	      ih6->ip_version_traffic_class_and_flow_label = 0x60;
  	      ih6->hop_limit = 0;
  	      pd->nexthdr = ah0->nexthdr;
  	      pd->icv_padding_len =
  		ah_calc_icv_padding_len (pd->icv_size, 1 /* is_ipv6 */ );
  	    }
  	  else
  	    {
  	      pd->tos = ih4->tos;
  	      pd->ttl = ih4->ttl;
  	      ih4->tos = 0;
  	      ih4->ttl = 0;
  	      ih4->checksum = 0;
  	      pd->icv_padding_len =
  		ah_calc_icv_padding_len (pd->icv_size, 0 /* is_ipv6 */ );
  	    }
  	}
  
      next:
        n_left -= 1;
        pd += 1;
        next += 1;
        b += 1;
      }
  
    n_left = from_frame->n_vectors;
    next = nexts;
    pd = pkt_data;
    b = bufs;
  
    vlib_node_increment_counter (vm, node->node_index, AH_DECRYPT_ERROR_RX_PKTS,
  			       n_left);
    vlib_increment_combined_counter (&ipsec_sa_counters, thread_index,
  				   current_sa_index, current_sa_pkts,
  				   current_sa_bytes);
  
    ah_process_ops (vm, node, ptd->integ_ops, bufs, nexts);
  
    while (n_left > 0)
      {
        ip4_header_t *oh4;
        ip6_header_t *oh6;
  
        if (next[0] < AH_DECRYPT_N_NEXT)
  	goto trace;
  
        sa0 = ipsec_sa_get (pd->sa_index);
  
        if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
  	{
  	  /* redo the anit-reply check. see esp_decrypt for details */
  	  if (ipsec_sa_anti_replay_check (sa0, pd->seq))
  	    {
  	      b[0]->error = node->errors[AH_DECRYPT_ERROR_REPLAY];
  	      next[0] = AH_DECRYPT_NEXT_DROP;
  	      goto trace;
  	    }
  	  ipsec_sa_anti_replay_advance (sa0, pd->seq);
  	}
  
        u16 ah_hdr_len = sizeof (ah_header_t) + pd->icv_size
  	+ pd->icv_padding_len;
        vlib_buffer_advance (b[0], pd->ip_hdr_size + ah_hdr_len);
        b[0]->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
  
        if (PREDICT_TRUE (ipsec_sa_is_set_IS_TUNNEL (sa0)))
  	{			/* tunnel mode */
  	  if (PREDICT_TRUE (pd->nexthdr_cached == IP_PROTOCOL_IP_IN_IP))
  	    next[0] = AH_DECRYPT_NEXT_IP4_INPUT;
  	  else if (pd->nexthdr_cached == IP_PROTOCOL_IPV6)
  	    next[0] = AH_DECRYPT_NEXT_IP6_INPUT;
  	  else
  	    {
  	      b[0]->error = node->errors[AH_DECRYPT_ERROR_DECRYPTION_FAILED];
  	      next[0] = AH_DECRYPT_NEXT_DROP;
  	      goto trace;
  	    }
  	}
        else
  	{			/* transport mode */
  	  if (is_ip6)
  	    {
  	      vlib_buffer_advance (b[0], -sizeof (ip6_header_t));
  	      oh6 = vlib_buffer_get_current (b[0]);
  	      if (ah_hdr_len >= sizeof (ip6_header_t))
  		clib_memcpy (oh6, b[0]->data + pd->current_data,
  			     sizeof (ip6_header_t));
  	      else
  		memmove (oh6, b[0]->data + pd->current_data,
  			 sizeof (ip6_header_t));
  
  	      next[0] = AH_DECRYPT_NEXT_IP6_INPUT;
  	      oh6->protocol = pd->nexthdr;
  	      oh6->hop_limit = pd->hop_limit;
  	      oh6->ip_version_traffic_class_and_flow_label =
  		pd->ip_version_traffic_class_and_flow_label;
  	      oh6->payload_length =
  		clib_host_to_net_u16 (vlib_buffer_length_in_chain
  				      (vm, b[0]) - sizeof (ip6_header_t));
  	    }
  	  else
  	    {
  	      vlib_buffer_advance (b[0], -sizeof (ip4_header_t));
  	      oh4 = vlib_buffer_get_current (b[0]);
  	      if (ah_hdr_len >= sizeof (ip4_header_t))
  		clib_memcpy (oh4, b[0]->data + pd->current_data,
  			     sizeof (ip4_header_t));
  	      else
  		memmove (oh4, b[0]->data + pd->current_data,
  			 sizeof (ip4_header_t));
  
  	      next[0] = AH_DECRYPT_NEXT_IP4_INPUT;
  	      oh4->ip_version_and_header_length = 0x45;
  	      oh4->fragment_id = 0;
  	      oh4->flags_and_fragment_offset = 0;
  	      oh4->protocol = pd->nexthdr_cached;
  	      oh4->length =
  		clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b[0]));
  	      oh4->ttl = pd->ttl;
  	      oh4->tos = pd->tos;
  	      oh4->checksum = ip4_header_checksum (oh4);
  	    }
  	}
  
        vnet_buffer (b[0])->sw_if_index[VLIB_TX] = (u32) ~ 0;
      trace:
        if (PREDICT_FALSE (b[0]->flags & VLIB_BUFFER_IS_TRACED))
  	{
  	  sa0 = ipsec_sa_get (vnet_buffer (b[0])->ipsec.sad_index);
  	  ah_decrypt_trace_t *tr =
  	    vlib_add_trace (vm, node, b[0], sizeof (*tr));
  	  tr->integ_alg = sa0->integ_alg;
  	  tr->seq_num = pd->seq;
  	}
  
        n_left -= 1;
        pd += 1;
        next += 1;
        b += 1;
      }
  
    n_left = from_frame->n_vectors;
    vlib_buffer_enqueue_to_next (vm, node, from, nexts, n_left);
  
    return n_left;
  }
  
  VLIB_NODE_FN (ah4_decrypt_node) (vlib_main_t * vm,
  				 vlib_node_runtime_t * node,
  				 vlib_frame_t * from_frame)
  {
    return ah_decrypt_inline (vm, node, from_frame, 0 /* is_ip6 */ );
  }
  
  /* *INDENT-OFF* */
  VLIB_REGISTER_NODE (ah4_decrypt_node) = {
    .name = "ah4-decrypt",
    .vector_size = sizeof (u32),
    .format_trace = format_ah_decrypt_trace,
    .type = VLIB_NODE_TYPE_INTERNAL,
  
    .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
    .error_strings = ah_decrypt_error_strings,
  
    .n_next_nodes = AH_DECRYPT_N_NEXT,
    .next_nodes = {
      [AH_DECRYPT_NEXT_DROP] = "ip4-drop",
      [AH_DECRYPT_NEXT_IP4_INPUT] = "ip4-input-no-checksum",
      [AH_DECRYPT_NEXT_IP6_INPUT] = "ip6-input",
      [AH_DECRYPT_NEXT_HANDOFF] = "ah4-decrypt-handoff",
    },
  };
  /* *INDENT-ON* */
  
  VLIB_NODE_FN (ah6_decrypt_node) (vlib_main_t * vm,
  				 vlib_node_runtime_t * node,
  				 vlib_frame_t * from_frame)
  {
    return ah_decrypt_inline (vm, node, from_frame, 1 /* is_ip6 */ );
  }
  
  /* *INDENT-OFF* */
  VLIB_REGISTER_NODE (ah6_decrypt_node) = {
    .name = "ah6-decrypt",
    .vector_size = sizeof (u32),
    .format_trace = format_ah_decrypt_trace,
    .type = VLIB_NODE_TYPE_INTERNAL,
  
    .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
    .error_strings = ah_decrypt_error_strings,
  
    .n_next_nodes = AH_DECRYPT_N_NEXT,
    .next_nodes = {
      [AH_DECRYPT_NEXT_DROP] = "ip6-drop",
      [AH_DECRYPT_NEXT_IP4_INPUT] = "ip4-input-no-checksum",
      [AH_DECRYPT_NEXT_IP6_INPUT] = "ip6-input",
      [AH_DECRYPT_NEXT_HANDOFF] = "ah6-decrypt-handoff",
    },
  };
  /* *INDENT-ON* */
  
  #ifndef CLIB_MARCH_VARIANT
  
  static clib_error_t *
  ah_decrypt_init (vlib_main_t *vm)
  {
    ipsec_main_t *im = &ipsec_main;
  
    im->ah4_dec_fq_index =
      vlib_frame_queue_main_init (ah4_decrypt_node.index, 0);
    im->ah6_dec_fq_index =
      vlib_frame_queue_main_init (ah6_decrypt_node.index, 0);
  
    return 0;
  }
  
  VLIB_INIT_FUNCTION (ah_decrypt_init);
  
  #endif
  
  /*
   * fd.io coding-style-patch-verification: ON
   *
   * Local Variables:
   * eval: (c-set-style "gnu")
   * End:
   */
  