src/vnet/ipsec/ah_decrypt.c

   1 /*
   2  * ah_decrypt.c : IPSec AH decrypt node
   3  *
   4  * Copyright (c) 2015 Cisco and/or its affiliates.
   5  * Licensed under the Apache License, Version 2.0 (the "License");
   6  * you may not use this file except in compliance with the License.
   7  * You may obtain a copy of the License at:
   8  *
   9  *     http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  * Unless required by applicable law or agreed to in writing, software
  12  * distributed under the License is distributed on an "AS IS" BASIS,
  13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14  * See the License for the specific language governing permissions and
  15  * limitations under the License.
  16  */
  17
  18 #include <vnet/vnet.h>
  19 #include <vnet/api_errno.h>
  20 #include <vnet/ip/ip.h>
  21
  22 #include <vnet/ipsec/ipsec.h>
  23 #include <vnet/ipsec/esp.h>
  24 #include <vnet/ipsec/ah.h>
  25 #include <vnet/ipsec/ipsec_io.h>
  26
  27 #define foreach_ah_decrypt_next \
  28   _ (DROP, "error-drop")        \
  29   _ (IP4_INPUT, "ip4-input")    \
  30   _ (IP6_INPUT, "ip6-input")
  31
  32 #define _(v, s) AH_DECRYPT_NEXT_##v,
  33 typedef enum
  34 {
  35   foreach_ah_decrypt_next
  36 #undef _
  37     AH_DECRYPT_N_NEXT,
  38 } ah_decrypt_next_t;
  39
  40 #define foreach_ah_decrypt_error                \
  41   _ (RX_PKTS, "AH pkts received")               \
  42   _ (DECRYPTION_FAILED, "AH decryption failed") \
  43   _ (INTEG_ERROR, "Integrity check failed")     \
  44   _ (NO_TAIL_SPACE, "not enough buffer tail space (dropped)")     \
  45   _ (DROP_FRAGMENTS, "IP fragments drop")       \
  46   _ (REPLAY, "SA replayed packet")
  47
  48 typedef enum
  49 {
  50 #define _(sym,str) AH_DECRYPT_ERROR_##sym,
  51   foreach_ah_decrypt_error
  52 #undef _
  53     AH_DECRYPT_N_ERROR,
  54 } ah_decrypt_error_t;
  55
  56 static char *ah_decrypt_error_strings[] = {
  57 #define _(sym,string) string,
  58   foreach_ah_decrypt_error
  59 #undef _
  60 };
  61
  62 typedef struct
  63 {
  64   ipsec_integ_alg_t integ_alg;
  65   u32 seq_num;
  66 } ah_decrypt_trace_t;
  67
  68 /* packet trace format function */
  69 static u8 *
  70 format_ah_decrypt_trace (u8 * s, va_list * args)
  71 {
  72   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  73   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  74   ah_decrypt_trace_t *t = va_arg (*args, ah_decrypt_trace_t *);
  75
  76   s = format (s, "ah: integrity %U seq-num %d",
  77               format_ipsec_integ_alg, t->integ_alg, t->seq_num);
  78   return s;
  79 }
  80
  81 typedef struct
  82 {
  83   union
  84   {
  85     struct
  86     {
  87       u8 hop_limit;
  88       u8 nexthdr;
  89       u32 ip_version_traffic_class_and_flow_label;
  90     };
  91
  92     struct
  93     {
  94       u8 ttl;
  95       u8 tos;
  96     };
  97   };
  98   u32 sa_index;
  99   u32 seq;
 100   u8 icv_padding_len;
 101   u8 icv_size;
 102   u8 ip_hdr_size;
 103   i16 current_data;
 104   u8 nexthdr_cached;
 105 } ah_decrypt_packet_data_t;
 106
 107 static_always_inline void
 108 ah_process_ops (vlib_main_t * vm, vlib_node_runtime_t * node,
 109                 vnet_crypto_op_t * ops, vlib_buffer_t * b[], u16 * nexts)
 110 {
 111   u32 n_fail, n_ops = vec_len (ops);
 112   vnet_crypto_op_t *op = ops;
 113
 114   if (n_ops == 0)
 115     return;
 116
 117   n_fail = n_ops - vnet_crypto_process_ops (vm, op, n_ops);
 118
 119   while (n_fail)
 120     {
 121       ASSERT (op - ops < n_ops);
 122
 123       if (op->status != VNET_CRYPTO_OP_STATUS_COMPLETED)
 124         {
 125           u32 bi = op->user_data;
 126           b[bi]->error = node->errors[AH_DECRYPT_ERROR_INTEG_ERROR];
 127           nexts[bi] = AH_DECRYPT_NEXT_DROP;
 128           n_fail--;
 129         }
 130       op++;
 131     }
 132 }
 133
 134 always_inline uword
 135 ah_decrypt_inline (vlib_main_t * vm,
 136                    vlib_node_runtime_t * node, vlib_frame_t * from_frame,
 137                    int is_ip6)
 138 {
 139   u32 n_left, *from;
 140   u32 thread_index = vm->thread_index;
 141   u16 buffer_data_size = vlib_buffer_get_default_data_size (vm);
 142   ah_decrypt_packet_data_t pkt_data[VLIB_FRAME_SIZE], *pd = pkt_data;
 143   vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b = bufs;
 144   u16 nexts[VLIB_FRAME_SIZE], *next = nexts;
 145   ipsec_main_t *im = &ipsec_main;
 146   ipsec_per_thread_data_t *ptd = vec_elt_at_index (im->ptd, thread_index);
 147   from = vlib_frame_vector_args (from_frame);
 148   n_left = from_frame->n_vectors;
 149   ipsec_sa_t *sa0 = 0;
 150   u32 current_sa_index = ~0, current_sa_bytes = 0, current_sa_pkts = 0;
 151
 152   clib_memset (pkt_data, 0, VLIB_FRAME_SIZE * sizeof (pkt_data[0]));
 153   vlib_get_buffers (vm, from, b, n_left);
 154   clib_memset_u16 (nexts, -1, n_left);
 155   vec_reset_length (ptd->integ_ops);
 156
 157   while (n_left > 0)
 158     {
 159       ah_header_t *ah0;
 160       ip4_header_t *ih4;
 161       ip6_header_t *ih6;
 162
 163       if (vnet_buffer (b[0])->ipsec.sad_index != current_sa_index)
 164         {
 165           if (current_sa_index != ~0)
 166             vlib_increment_combined_counter (&ipsec_sa_counters, thread_index,
 167                                              current_sa_index,
 168                                              current_sa_pkts,
 169                                              current_sa_bytes);
 170           current_sa_index = vnet_buffer (b[0])->ipsec.sad_index;
 171           sa0 = pool_elt_at_index (im->sad, current_sa_index);
 172
 173           current_sa_bytes = current_sa_pkts = 0;
 174           vlib_prefetch_combined_counter (&ipsec_sa_counters,
 175                                           thread_index, current_sa_index);
 176         }
 177
 178       pd->sa_index = current_sa_index;
 179
 180       ih4 = vlib_buffer_get_current (b[0]);
 181       ih6 = vlib_buffer_get_current (b[0]);
 182       pd->current_data = b[0]->current_data;
 183
 184       if (is_ip6)
 185         {
 186           ip6_ext_header_t *prev = NULL;
 187           ip6_ext_header_find_t (ih6, prev, ah0, IP_PROTOCOL_IPSEC_AH);
 188           pd->ip_hdr_size = sizeof (ip6_header_t);
 189           ASSERT ((u8 *) ah0 - (u8 *) ih6 == pd->ip_hdr_size);
 190         }
 191       else
 192         {
 193           if (ip4_is_fragment (ih4))
 194             {
 195               b[0]->error = node->errors[AH_DECRYPT_ERROR_DROP_FRAGMENTS];
 196               next[0] = AH_DECRYPT_NEXT_DROP;
 197               goto next;
 198             }
 199           pd->ip_hdr_size = ip4_header_bytes (ih4);
 200           ah0 = (ah_header_t *) ((u8 *) ih4 + pd->ip_hdr_size);
 201         }
 202
 203       pd->seq = clib_host_to_net_u32 (ah0->seq_no);
 204
 205       /* anti-replay check */
 206       if (ipsec_sa_anti_replay_check (sa0, &ah0->seq_no))
 207         {
 208           b[0]->error = node->errors[AH_DECRYPT_ERROR_REPLAY];
 209           next[0] = AH_DECRYPT_NEXT_DROP;
 210           goto next;
 211         }
 212
 213       current_sa_bytes += b[0]->current_length;
 214       current_sa_pkts += 1;
 215
 216       pd->icv_size = sa0->integ_icv_size;
 217       pd->nexthdr_cached = ah0->nexthdr;
 218       if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
 219         {
 220           if (PREDICT_FALSE (ipsec_sa_is_set_USE_ESN (sa0) &&
 221                              pd->current_data + b[0]->current_length
 222                              + sizeof (u32) > buffer_data_size))
 223             {
 224               b[0]->error = node->errors[AH_DECRYPT_ERROR_NO_TAIL_SPACE];
 225               next[0] = AH_DECRYPT_NEXT_DROP;
 226               goto next;
 227             }
 228
 229           vnet_crypto_op_t *op;
 230           vec_add2_aligned (ptd->integ_ops, op, 1, CLIB_CACHE_LINE_BYTES);
 231           vnet_crypto_op_init (op, sa0->integ_op_id);
 232
 233           op->src = (u8 *) ih4;
 234           op->len = b[0]->current_length;
 235           op->digest = (u8 *) ih4 - pd->icv_size;
 236           op->flags = VNET_CRYPTO_OP_FLAG_HMAC_CHECK;
 237           op->digest_len = pd->icv_size;
 238           op->key_index = sa0->integ_key_index;
 239           op->user_data = b - bufs;
 240           if (ipsec_sa_is_set_USE_ESN (sa0))
 241             {
 242               u32 seq_hi = clib_host_to_net_u32 (sa0->seq_hi);
 243
 244               op->len += sizeof (seq_hi);
 245               clib_memcpy (op->src + b[0]->current_length, &seq_hi,
 246                            sizeof (seq_hi));
 247             }
 248           clib_memcpy (op->digest, ah0->auth_data, pd->icv_size);
 249           clib_memset (ah0->auth_data, 0, pd->icv_size);
 250
 251           if (is_ip6)
 252             {
 253               pd->ip_version_traffic_class_and_flow_label =
 254                 ih6->ip_version_traffic_class_and_flow_label;
 255               pd->hop_limit = ih6->hop_limit;
 256               ih6->ip_version_traffic_class_and_flow_label = 0x60;
 257               ih6->hop_limit = 0;
 258               pd->nexthdr = ah0->nexthdr;
 259               pd->icv_padding_len =
 260                 ah_calc_icv_padding_len (pd->icv_size, 1 /* is_ipv6 */ );
 261             }
 262           else
 263             {
 264               pd->tos = ih4->tos;
 265               pd->ttl = ih4->ttl;
 266               ih4->tos = 0;
 267               ih4->ttl = 0;
 268               ih4->checksum = 0;
 269               pd->icv_padding_len =
 270                 ah_calc_icv_padding_len (pd->icv_size, 0 /* is_ipv6 */ );
 271             }
 272         }
 273
 274     next:
 275       n_left -= 1;
 276       pd += 1;
 277       next += 1;
 278       b += 1;
 279     }
 280
 281   n_left = from_frame->n_vectors;
 282   next = nexts;
 283   pd = pkt_data;
 284   b = bufs;
 285
 286   vlib_node_increment_counter (vm, node->node_index, AH_DECRYPT_ERROR_RX_PKTS,
 287                                n_left);
 288   vlib_increment_combined_counter (&ipsec_sa_counters, thread_index,
 289                                    current_sa_index, current_sa_pkts,
 290                                    current_sa_bytes);
 291
 292   ah_process_ops (vm, node, ptd->integ_ops, bufs, nexts);
 293
 294   while (n_left > 0)
 295     {
 296       ip4_header_t *oh4;
 297       ip6_header_t *oh6;
 298
 299       if (next[0] < AH_DECRYPT_N_NEXT)
 300         goto trace;
 301
 302       sa0 = vec_elt_at_index (im->sad, pd->sa_index);
 303
 304       if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
 305         {
 306           ipsec_sa_anti_replay_advance (sa0, clib_host_to_net_u32 (pd->seq));
 307         }
 308
 309       u16 ah_hdr_len = sizeof (ah_header_t) + pd->icv_size
 310         + pd->icv_padding_len;
 311       vlib_buffer_advance (b[0], pd->ip_hdr_size + ah_hdr_len);
 312       b[0]->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
 313
 314       if (PREDICT_TRUE (ipsec_sa_is_set_IS_TUNNEL (sa0)))
 315         {                       /* tunnel mode */
 316           if (PREDICT_TRUE (pd->nexthdr_cached == IP_PROTOCOL_IP_IN_IP))
 317             next[0] = AH_DECRYPT_NEXT_IP4_INPUT;
 318           else if (pd->nexthdr_cached == IP_PROTOCOL_IPV6)
 319             next[0] = AH_DECRYPT_NEXT_IP6_INPUT;
 320           else
 321             {
 322               b[0]->error = node->errors[AH_DECRYPT_ERROR_DECRYPTION_FAILED];
 323               next[0] = AH_DECRYPT_NEXT_DROP;
 324               goto trace;
 325             }
 326         }
 327       else
 328         {                       /* transport mode */
 329           if (is_ip6)
 330             {
 331               vlib_buffer_advance (b[0], -sizeof (ip6_header_t));
 332               oh6 = vlib_buffer_get_current (b[0]);
 333               if (ah_hdr_len >= sizeof (ip6_header_t))
 334                 clib_memcpy (oh6, b[0]->data + pd->current_data,
 335                              sizeof (ip6_header_t));
 336               else
 337                 memmove (oh6, b[0]->data + pd->current_data,
 338                          sizeof (ip6_header_t));
 339
 340               next[0] = AH_DECRYPT_NEXT_IP6_INPUT;
 341               oh6->protocol = pd->nexthdr;
 342               oh6->hop_limit = pd->hop_limit;
 343               oh6->ip_version_traffic_class_and_flow_label =
 344                 pd->ip_version_traffic_class_and_flow_label;
 345               oh6->payload_length =
 346                 clib_host_to_net_u16 (vlib_buffer_length_in_chain
 347                                       (vm, b[0]) - sizeof (ip6_header_t));
 348             }
 349           else
 350             {
 351               vlib_buffer_advance (b[0], -sizeof (ip4_header_t));
 352               oh4 = vlib_buffer_get_current (b[0]);
 353               if (ah_hdr_len >= sizeof (ip4_header_t))
 354                 clib_memcpy (oh4, b[0]->data + pd->current_data,
 355                              sizeof (ip4_header_t));
 356               else
 357                 memmove (oh4, b[0]->data + pd->current_data,
 358                          sizeof (ip4_header_t));
 359
 360               next[0] = AH_DECRYPT_NEXT_IP4_INPUT;
 361               oh4->ip_version_and_header_length = 0x45;
 362               oh4->fragment_id = 0;
 363               oh4->flags_and_fragment_offset = 0;
 364               oh4->protocol = pd->nexthdr_cached;
 365               oh4->length =
 366                 clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b[0]));
 367               oh4->ttl = pd->ttl;
 368               oh4->tos = pd->tos;
 369               oh4->checksum = ip4_header_checksum (oh4);
 370             }
 371         }
 372
 373       vnet_buffer (b[0])->sw_if_index[VLIB_TX] = (u32) ~ 0;
 374     trace:
 375       if (PREDICT_FALSE (b[0]->flags & VLIB_BUFFER_IS_TRACED))
 376         {
 377           sa0 = pool_elt_at_index (im->sad,
 378                                    vnet_buffer (b[0])->ipsec.sad_index);
 379           ah_decrypt_trace_t *tr =
 380             vlib_add_trace (vm, node, b[0], sizeof (*tr));
 381           tr->integ_alg = sa0->integ_alg;
 382           tr->seq_num = pd->seq;
 383         }
 384
 385       n_left -= 1;
 386       pd += 1;
 387       next += 1;
 388       b += 1;
 389     }
 390
 391   n_left = from_frame->n_vectors;
 392   vlib_buffer_enqueue_to_next (vm, node, from, nexts, n_left);
 393
 394   return n_left;
 395 }
 396
 397 VLIB_NODE_FN (ah4_decrypt_node) (vlib_main_t * vm,
 398                                  vlib_node_runtime_t * node,
 399                                  vlib_frame_t * from_frame)
 400 {
 401   return ah_decrypt_inline (vm, node, from_frame, 0 /* is_ip6 */ );
 402 }
 403
 404 /* *INDENT-OFF* */
 405 VLIB_REGISTER_NODE (ah4_decrypt_node) = {
 406   .name = "ah4-decrypt",
 407   .vector_size = sizeof (u32),
 408   .format_trace = format_ah_decrypt_trace,
 409   .type = VLIB_NODE_TYPE_INTERNAL,
 410
 411   .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
 412   .error_strings = ah_decrypt_error_strings,
 413
 414   .n_next_nodes = AH_DECRYPT_N_NEXT,
 415   .next_nodes = {
 416 #define _(s,n) [AH_DECRYPT_NEXT_##s] = n,
 417     foreach_ah_decrypt_next
 418 #undef _
 419   },
 420 };
 421 /* *INDENT-ON* */
 422
 423 VLIB_NODE_FN (ah6_decrypt_node) (vlib_main_t * vm,
 424                                  vlib_node_runtime_t * node,
 425                                  vlib_frame_t * from_frame)
 426 {
 427   return ah_decrypt_inline (vm, node, from_frame, 1 /* is_ip6 */ );
 428 }
 429
 430 /* *INDENT-OFF* */
 431 VLIB_REGISTER_NODE (ah6_decrypt_node) = {
 432   .name = "ah6-decrypt",
 433   .vector_size = sizeof (u32),
 434   .format_trace = format_ah_decrypt_trace,
 435   .type = VLIB_NODE_TYPE_INTERNAL,
 436
 437   .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
 438   .error_strings = ah_decrypt_error_strings,
 439
 440   .n_next_nodes = AH_DECRYPT_N_NEXT,
 441   .next_nodes = {
 442 #define _(s,n) [AH_DECRYPT_NEXT_##s] = n,
 443     foreach_ah_decrypt_next
 444 #undef _
 445   },
 446 };
 447 /* *INDENT-ON* */
 448
 449 /*
 450  * fd.io coding-style-patch-verification: ON
 451  *
 452  * Local Variables:
 453  * eval: (c-set-style "gnu")
 454  * End:
 455  */