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   _(HANDOFF, "handoff")
  32
  33 #define _(v, s) AH_DECRYPT_NEXT_##v,
  34 typedef enum
  35 {
  36   foreach_ah_decrypt_next
  37 #undef _
  38     AH_DECRYPT_N_NEXT,
  39 } ah_decrypt_next_t;
  40
  41 #define foreach_ah_decrypt_error                \
  42   _ (RX_PKTS, "AH pkts received")               \
  43   _ (DECRYPTION_FAILED, "AH decryption failed") \
  44   _ (INTEG_ERROR, "Integrity check failed")     \
  45   _ (NO_TAIL_SPACE, "not enough buffer tail space (dropped)")     \
  46   _ (DROP_FRAGMENTS, "IP fragments drop")       \
  47   _ (REPLAY, "SA replayed packet")
  48
  49 typedef enum
  50 {
  51 #define _(sym,str) AH_DECRYPT_ERROR_##sym,
  52   foreach_ah_decrypt_error
  53 #undef _
  54     AH_DECRYPT_N_ERROR,
  55 } ah_decrypt_error_t;
  56
  57 static char *ah_decrypt_error_strings[] = {
  58 #define _(sym,string) string,
  59   foreach_ah_decrypt_error
  60 #undef _
  61 };
  62
  63 typedef struct
  64 {
  65   ipsec_integ_alg_t integ_alg;
  66   u32 seq_num;
  67 } ah_decrypt_trace_t;
  68
  69 /* packet trace format function */
  70 static u8 *
  71 format_ah_decrypt_trace (u8 * s, va_list * args)
  72 {
  73   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  74   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  75   ah_decrypt_trace_t *t = va_arg (*args, ah_decrypt_trace_t *);
  76
  77   s = format (s, "ah: integrity %U seq-num %d",
  78               format_ipsec_integ_alg, t->integ_alg, t->seq_num);
  79   return s;
  80 }
  81
  82 typedef struct
  83 {
  84   union
  85   {
  86     struct
  87     {
  88       u8 hop_limit;
  89       u8 nexthdr;
  90       u32 ip_version_traffic_class_and_flow_label;
  91     };
  92
  93     struct
  94     {
  95       u8 ttl;
  96       u8 tos;
  97     };
  98   };
  99   u32 sa_index;
 100   u32 seq;
 101   u32 seq_hi;
 102   u8 icv_padding_len;
 103   u8 icv_size;
 104   u8 ip_hdr_size;
 105   i16 current_data;
 106   u8 nexthdr_cached;
 107 } ah_decrypt_packet_data_t;
 108
 109 static_always_inline void
 110 ah_process_ops (vlib_main_t * vm, vlib_node_runtime_t * node,
 111                 vnet_crypto_op_t * ops, vlib_buffer_t * b[], u16 * nexts)
 112 {
 113   u32 n_fail, n_ops = vec_len (ops);
 114   vnet_crypto_op_t *op = ops;
 115
 116   if (n_ops == 0)
 117     return;
 118
 119   n_fail = n_ops - vnet_crypto_process_ops (vm, op, n_ops);
 120
 121   while (n_fail)
 122     {
 123       ASSERT (op - ops < n_ops);
 124
 125       if (op->status != VNET_CRYPTO_OP_STATUS_COMPLETED)
 126         {
 127           u32 bi = op->user_data;
 128           b[bi]->error = node->errors[AH_DECRYPT_ERROR_INTEG_ERROR];
 129           nexts[bi] = AH_DECRYPT_NEXT_DROP;
 130           n_fail--;
 131         }
 132       op++;
 133     }
 134 }
 135
 136 always_inline uword
 137 ah_decrypt_inline (vlib_main_t * vm,
 138                    vlib_node_runtime_t * node, vlib_frame_t * from_frame,
 139                    int is_ip6)
 140 {
 141   u32 n_left, *from;
 142   u32 thread_index = vm->thread_index;
 143   u16 buffer_data_size = vlib_buffer_get_default_data_size (vm);
 144   ah_decrypt_packet_data_t pkt_data[VLIB_FRAME_SIZE], *pd = pkt_data;
 145   vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b = bufs;
 146   u16 nexts[VLIB_FRAME_SIZE], *next = nexts;
 147   ipsec_main_t *im = &ipsec_main;
 148   ipsec_per_thread_data_t *ptd = vec_elt_at_index (im->ptd, thread_index);
 149   from = vlib_frame_vector_args (from_frame);
 150   n_left = from_frame->n_vectors;
 151   ipsec_sa_t *sa0 = 0;
 152   u32 current_sa_index = ~0, current_sa_bytes = 0, current_sa_pkts = 0;
 153
 154   clib_memset (pkt_data, 0, VLIB_FRAME_SIZE * sizeof (pkt_data[0]));
 155   vlib_get_buffers (vm, from, b, n_left);
 156   clib_memset_u16 (nexts, -1, n_left);
 157   vec_reset_length (ptd->integ_ops);
 158
 159   while (n_left > 0)
 160     {
 161       ah_header_t *ah0;
 162       ip4_header_t *ih4;
 163       ip6_header_t *ih6;
 164
 165       if (vnet_buffer (b[0])->ipsec.sad_index != current_sa_index)
 166         {
 167           if (current_sa_index != ~0)
 168             vlib_increment_combined_counter (&ipsec_sa_counters, thread_index,
 169                                              current_sa_index,
 170                                              current_sa_pkts,
 171                                              current_sa_bytes);
 172           current_sa_index = vnet_buffer (b[0])->ipsec.sad_index;
 173           sa0 = ipsec_sa_get (current_sa_index);
 174
 175           current_sa_bytes = current_sa_pkts = 0;
 176           vlib_prefetch_combined_counter (&ipsec_sa_counters,
 177                                           thread_index, current_sa_index);
 178         }
 179
 180       if (PREDICT_FALSE (~0 == sa0->thread_index))
 181         {
 182           /* this is the first packet to use this SA, claim the SA
 183            * for this thread. this could happen simultaneously on
 184            * another thread */
 185           clib_atomic_cmp_and_swap (&sa0->thread_index, ~0,
 186                                     ipsec_sa_assign_thread (thread_index));
 187         }
 188
 189       if (PREDICT_TRUE (thread_index != sa0->thread_index))
 190         {
 191           vnet_buffer (b[0])->ipsec.thread_index = sa0->thread_index;
 192           next[0] = AH_DECRYPT_NEXT_HANDOFF;
 193           goto next;
 194         }
 195
 196       pd->sa_index = current_sa_index;
 197
 198       ih4 = vlib_buffer_get_current (b[0]);
 199       ih6 = vlib_buffer_get_current (b[0]);
 200       pd->current_data = b[0]->current_data;
 201
 202       if (is_ip6)
 203         {
 204           ip6_ext_header_t *prev = NULL;
 205           ah0 =
 206             ip6_ext_header_find (vm, b[0], ih6, IP_PROTOCOL_IPSEC_AH, &prev);
 207           pd->ip_hdr_size = sizeof (ip6_header_t);
 208           ASSERT ((u8 *) ah0 - (u8 *) ih6 == pd->ip_hdr_size);
 209         }
 210       else
 211         {
 212           if (ip4_is_fragment (ih4))
 213             {
 214               b[0]->error = node->errors[AH_DECRYPT_ERROR_DROP_FRAGMENTS];
 215               next[0] = AH_DECRYPT_NEXT_DROP;
 216               goto next;
 217             }
 218           pd->ip_hdr_size = ip4_header_bytes (ih4);
 219           ah0 = (ah_header_t *) ((u8 *) ih4 + pd->ip_hdr_size);
 220         }
 221
 222       pd->seq = clib_host_to_net_u32 (ah0->seq_no);
 223
 224       /* anti-replay check */
 225       if (ipsec_sa_anti_replay_and_sn_advance (sa0, pd->seq, ~0, false,
 226                                                &pd->seq_hi))
 227         {
 228           b[0]->error = node->errors[AH_DECRYPT_ERROR_REPLAY];
 229           next[0] = AH_DECRYPT_NEXT_DROP;
 230           goto next;
 231         }
 232
 233       current_sa_bytes += b[0]->current_length;
 234       current_sa_pkts += 1;
 235
 236       pd->icv_size = sa0->integ_icv_size;
 237       pd->nexthdr_cached = ah0->nexthdr;
 238       if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
 239         {
 240           if (PREDICT_FALSE (ipsec_sa_is_set_USE_ESN (sa0) &&
 241                              pd->current_data + b[0]->current_length
 242                              + sizeof (u32) > buffer_data_size))
 243             {
 244               b[0]->error = node->errors[AH_DECRYPT_ERROR_NO_TAIL_SPACE];
 245               next[0] = AH_DECRYPT_NEXT_DROP;
 246               goto next;
 247             }
 248
 249           vnet_crypto_op_t *op;
 250           vec_add2_aligned (ptd->integ_ops, op, 1, CLIB_CACHE_LINE_BYTES);
 251           vnet_crypto_op_init (op, sa0->integ_op_id);
 252
 253           op->src = (u8 *) ih4;
 254           op->len = b[0]->current_length;
 255           op->digest = (u8 *) ih4 - pd->icv_size;
 256           op->flags = VNET_CRYPTO_OP_FLAG_HMAC_CHECK;
 257           op->digest_len = pd->icv_size;
 258           op->key_index = sa0->integ_key_index;
 259           op->user_data = b - bufs;
 260           if (ipsec_sa_is_set_USE_ESN (sa0))
 261             {
 262               u32 seq_hi = clib_host_to_net_u32 (pd->seq_hi);
 263
 264               op->len += sizeof (seq_hi);
 265               clib_memcpy (op->src + b[0]->current_length, &seq_hi,
 266                            sizeof (seq_hi));
 267             }
 268           clib_memcpy (op->digest, ah0->auth_data, pd->icv_size);
 269           clib_memset (ah0->auth_data, 0, pd->icv_size);
 270
 271           if (is_ip6)
 272             {
 273               pd->ip_version_traffic_class_and_flow_label =
 274                 ih6->ip_version_traffic_class_and_flow_label;
 275               pd->hop_limit = ih6->hop_limit;
 276               ih6->ip_version_traffic_class_and_flow_label = 0x60;
 277               ih6->hop_limit = 0;
 278               pd->nexthdr = ah0->nexthdr;
 279               pd->icv_padding_len =
 280                 ah_calc_icv_padding_len (pd->icv_size, 1 /* is_ipv6 */ );
 281             }
 282           else
 283             {
 284               pd->tos = ih4->tos;
 285               pd->ttl = ih4->ttl;
 286               ih4->tos = 0;
 287               ih4->ttl = 0;
 288               ih4->checksum = 0;
 289               pd->icv_padding_len =
 290                 ah_calc_icv_padding_len (pd->icv_size, 0 /* is_ipv6 */ );
 291             }
 292         }
 293
 294     next:
 295       n_left -= 1;
 296       pd += 1;
 297       next += 1;
 298       b += 1;
 299     }
 300
 301   n_left = from_frame->n_vectors;
 302   next = nexts;
 303   pd = pkt_data;
 304   b = bufs;
 305
 306   vlib_node_increment_counter (vm, node->node_index, AH_DECRYPT_ERROR_RX_PKTS,
 307                                n_left);
 308   vlib_increment_combined_counter (&ipsec_sa_counters, thread_index,
 309                                    current_sa_index, current_sa_pkts,
 310                                    current_sa_bytes);
 311
 312   ah_process_ops (vm, node, ptd->integ_ops, bufs, nexts);
 313
 314   while (n_left > 0)
 315     {
 316       ip4_header_t *oh4;
 317       ip6_header_t *oh6;
 318
 319       if (next[0] < AH_DECRYPT_N_NEXT)
 320         goto trace;
 321
 322       sa0 = ipsec_sa_get (pd->sa_index);
 323
 324       if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
 325         {
 326           /* redo the anit-reply check. see esp_decrypt for details */
 327           if (ipsec_sa_anti_replay_and_sn_advance (sa0, pd->seq, pd->seq_hi,
 328                                                    true, NULL))
 329             {
 330               b[0]->error = node->errors[AH_DECRYPT_ERROR_REPLAY];
 331               next[0] = AH_DECRYPT_NEXT_DROP;
 332               goto trace;
 333             }
 334           ipsec_sa_anti_replay_advance (sa0, pd->seq, pd->seq_hi);
 335         }
 336
 337       u16 ah_hdr_len = sizeof (ah_header_t) + pd->icv_size
 338         + pd->icv_padding_len;
 339       vlib_buffer_advance (b[0], pd->ip_hdr_size + ah_hdr_len);
 340       b[0]->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
 341
 342       if (PREDICT_TRUE (ipsec_sa_is_set_IS_TUNNEL (sa0)))
 343         {                       /* tunnel mode */
 344           if (PREDICT_TRUE (pd->nexthdr_cached == IP_PROTOCOL_IP_IN_IP))
 345             next[0] = AH_DECRYPT_NEXT_IP4_INPUT;
 346           else if (pd->nexthdr_cached == IP_PROTOCOL_IPV6)
 347             next[0] = AH_DECRYPT_NEXT_IP6_INPUT;
 348           else
 349             {
 350               b[0]->error = node->errors[AH_DECRYPT_ERROR_DECRYPTION_FAILED];
 351               next[0] = AH_DECRYPT_NEXT_DROP;
 352               goto trace;
 353             }
 354         }
 355       else
 356         {                       /* transport mode */
 357           if (is_ip6)
 358             {
 359               vlib_buffer_advance (b[0], -sizeof (ip6_header_t));
 360               oh6 = vlib_buffer_get_current (b[0]);
 361               if (ah_hdr_len >= sizeof (ip6_header_t))
 362                 clib_memcpy (oh6, b[0]->data + pd->current_data,
 363                              sizeof (ip6_header_t));
 364               else
 365                 memmove (oh6, b[0]->data + pd->current_data,
 366                          sizeof (ip6_header_t));
 367
 368               next[0] = AH_DECRYPT_NEXT_IP6_INPUT;
 369               oh6->protocol = pd->nexthdr;
 370               oh6->hop_limit = pd->hop_limit;
 371               oh6->ip_version_traffic_class_and_flow_label =
 372                 pd->ip_version_traffic_class_and_flow_label;
 373               oh6->payload_length =
 374                 clib_host_to_net_u16 (vlib_buffer_length_in_chain
 375                                       (vm, b[0]) - sizeof (ip6_header_t));
 376             }
 377           else
 378             {
 379               vlib_buffer_advance (b[0], -sizeof (ip4_header_t));
 380               oh4 = vlib_buffer_get_current (b[0]);
 381               if (ah_hdr_len >= sizeof (ip4_header_t))
 382                 clib_memcpy (oh4, b[0]->data + pd->current_data,
 383                              sizeof (ip4_header_t));
 384               else
 385                 memmove (oh4, b[0]->data + pd->current_data,
 386                          sizeof (ip4_header_t));
 387
 388               next[0] = AH_DECRYPT_NEXT_IP4_INPUT;
 389               oh4->ip_version_and_header_length = 0x45;
 390               oh4->fragment_id = 0;
 391               oh4->flags_and_fragment_offset = 0;
 392               oh4->protocol = pd->nexthdr_cached;
 393               oh4->length =
 394                 clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b[0]));
 395               oh4->ttl = pd->ttl;
 396               oh4->tos = pd->tos;
 397               oh4->checksum = ip4_header_checksum (oh4);
 398             }
 399         }
 400
 401       vnet_buffer (b[0])->sw_if_index[VLIB_TX] = (u32) ~ 0;
 402     trace:
 403       if (PREDICT_FALSE (b[0]->flags & VLIB_BUFFER_IS_TRACED))
 404         {
 405           sa0 = ipsec_sa_get (vnet_buffer (b[0])->ipsec.sad_index);
 406           ah_decrypt_trace_t *tr =
 407             vlib_add_trace (vm, node, b[0], sizeof (*tr));
 408           tr->integ_alg = sa0->integ_alg;
 409           tr->seq_num = pd->seq;
 410         }
 411
 412       n_left -= 1;
 413       pd += 1;
 414       next += 1;
 415       b += 1;
 416     }
 417
 418   n_left = from_frame->n_vectors;
 419   vlib_buffer_enqueue_to_next (vm, node, from, nexts, n_left);
 420
 421   return n_left;
 422 }
 423
 424 VLIB_NODE_FN (ah4_decrypt_node) (vlib_main_t * vm,
 425                                  vlib_node_runtime_t * node,
 426                                  vlib_frame_t * from_frame)
 427 {
 428   return ah_decrypt_inline (vm, node, from_frame, 0 /* is_ip6 */ );
 429 }
 430
 431 /* *INDENT-OFF* */
 432 VLIB_REGISTER_NODE (ah4_decrypt_node) = {
 433   .name = "ah4-decrypt",
 434   .vector_size = sizeof (u32),
 435   .format_trace = format_ah_decrypt_trace,
 436   .type = VLIB_NODE_TYPE_INTERNAL,
 437
 438   .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
 439   .error_strings = ah_decrypt_error_strings,
 440
 441   .n_next_nodes = AH_DECRYPT_N_NEXT,
 442   .next_nodes = {
 443     [AH_DECRYPT_NEXT_DROP] = "ip4-drop",
 444     [AH_DECRYPT_NEXT_IP4_INPUT] = "ip4-input-no-checksum",
 445     [AH_DECRYPT_NEXT_IP6_INPUT] = "ip6-input",
 446     [AH_DECRYPT_NEXT_HANDOFF] = "ah4-decrypt-handoff",
 447   },
 448 };
 449 /* *INDENT-ON* */
 450
 451 VLIB_NODE_FN (ah6_decrypt_node) (vlib_main_t * vm,
 452                                  vlib_node_runtime_t * node,
 453                                  vlib_frame_t * from_frame)
 454 {
 455   return ah_decrypt_inline (vm, node, from_frame, 1 /* is_ip6 */ );
 456 }
 457
 458 /* *INDENT-OFF* */
 459 VLIB_REGISTER_NODE (ah6_decrypt_node) = {
 460   .name = "ah6-decrypt",
 461   .vector_size = sizeof (u32),
 462   .format_trace = format_ah_decrypt_trace,
 463   .type = VLIB_NODE_TYPE_INTERNAL,
 464
 465   .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
 466   .error_strings = ah_decrypt_error_strings,
 467
 468   .n_next_nodes = AH_DECRYPT_N_NEXT,
 469   .next_nodes = {
 470     [AH_DECRYPT_NEXT_DROP] = "ip6-drop",
 471     [AH_DECRYPT_NEXT_IP4_INPUT] = "ip4-input-no-checksum",
 472     [AH_DECRYPT_NEXT_IP6_INPUT] = "ip6-input",
 473     [AH_DECRYPT_NEXT_HANDOFF] = "ah6-decrypt-handoff",
 474   },
 475 };
 476 /* *INDENT-ON* */
 477
 478 #ifndef CLIB_MARCH_VARIANT
 479
 480 static clib_error_t *
 481 ah_decrypt_init (vlib_main_t *vm)
 482 {
 483   ipsec_main_t *im = &ipsec_main;
 484
 485   im->ah4_dec_fq_index =
 486     vlib_frame_queue_main_init (ah4_decrypt_node.index, 0);
 487   im->ah6_dec_fq_index =
 488     vlib_frame_queue_main_init (ah6_decrypt_node.index, 0);
 489
 490   return 0;
 491 }
 492
 493 VLIB_INIT_FUNCTION (ah_decrypt_init);
 494
 495 #endif
 496
 497 /*
 498  * fd.io coding-style-patch-verification: ON
 499  *
 500  * Local Variables:
 501  * eval: (c-set-style "gnu")
 502  * End:
 503  */