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   u8 icv_padding_len;
 102   u8 icv_size;
 103   u8 ip_hdr_size;
 104   i16 current_data;
 105   u8 nexthdr_cached;
 106 } ah_decrypt_packet_data_t;
 107
 108 static_always_inline void
 109 ah_process_ops (vlib_main_t * vm, vlib_node_runtime_t * node,
 110                 vnet_crypto_op_t * ops, vlib_buffer_t * b[], u16 * nexts)
 111 {
 112   u32 n_fail, n_ops = vec_len (ops);
 113   vnet_crypto_op_t *op = ops;
 114
 115   if (n_ops == 0)
 116     return;
 117
 118   n_fail = n_ops - vnet_crypto_process_ops (vm, op, n_ops);
 119
 120   while (n_fail)
 121     {
 122       ASSERT (op - ops < n_ops);
 123
 124       if (op->status != VNET_CRYPTO_OP_STATUS_COMPLETED)
 125         {
 126           u32 bi = op->user_data;
 127           b[bi]->error = node->errors[AH_DECRYPT_ERROR_INTEG_ERROR];
 128           nexts[bi] = AH_DECRYPT_NEXT_DROP;
 129           n_fail--;
 130         }
 131       op++;
 132     }
 133 }
 134
 135 always_inline uword
 136 ah_decrypt_inline (vlib_main_t * vm,
 137                    vlib_node_runtime_t * node, vlib_frame_t * from_frame,
 138                    int is_ip6)
 139 {
 140   u32 n_left, *from;
 141   u32 thread_index = vm->thread_index;
 142   u16 buffer_data_size = vlib_buffer_get_default_data_size (vm);
 143   ah_decrypt_packet_data_t pkt_data[VLIB_FRAME_SIZE], *pd = pkt_data;
 144   vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b = bufs;
 145   u16 nexts[VLIB_FRAME_SIZE], *next = nexts;
 146   ipsec_main_t *im = &ipsec_main;
 147   ipsec_per_thread_data_t *ptd = vec_elt_at_index (im->ptd, thread_index);
 148   from = vlib_frame_vector_args (from_frame);
 149   n_left = from_frame->n_vectors;
 150   ipsec_sa_t *sa0 = 0;
 151   u32 current_sa_index = ~0, current_sa_bytes = 0, current_sa_pkts = 0;
 152
 153   clib_memset (pkt_data, 0, VLIB_FRAME_SIZE * sizeof (pkt_data[0]));
 154   vlib_get_buffers (vm, from, b, n_left);
 155   clib_memset_u16 (nexts, -1, n_left);
 156   vec_reset_length (ptd->integ_ops);
 157
 158   while (n_left > 0)
 159     {
 160       ah_header_t *ah0;
 161       ip4_header_t *ih4;
 162       ip6_header_t *ih6;
 163
 164       if (vnet_buffer (b[0])->ipsec.sad_index != current_sa_index)
 165         {
 166           if (current_sa_index != ~0)
 167             vlib_increment_combined_counter (&ipsec_sa_counters, thread_index,
 168                                              current_sa_index,
 169                                              current_sa_pkts,
 170                                              current_sa_bytes);
 171           current_sa_index = vnet_buffer (b[0])->ipsec.sad_index;
 172           sa0 = pool_elt_at_index (im->sad, current_sa_index);
 173
 174           current_sa_bytes = current_sa_pkts = 0;
 175           vlib_prefetch_combined_counter (&ipsec_sa_counters,
 176                                           thread_index, current_sa_index);
 177         }
 178
 179       if (PREDICT_FALSE (~0 == sa0->decrypt_thread_index))
 180         {
 181           /* this is the first packet to use this SA, claim the SA
 182            * for this thread. this could happen simultaneously on
 183            * another thread */
 184           clib_atomic_cmp_and_swap (&sa0->decrypt_thread_index, ~0,
 185                                     ipsec_sa_assign_thread (thread_index));
 186         }
 187
 188       if (PREDICT_TRUE (thread_index != sa0->decrypt_thread_index))
 189         {
 190           next[0] = AH_DECRYPT_NEXT_HANDOFF;
 191           goto next;
 192         }
 193
 194       pd->sa_index = current_sa_index;
 195
 196       ih4 = vlib_buffer_get_current (b[0]);
 197       ih6 = vlib_buffer_get_current (b[0]);
 198       pd->current_data = b[0]->current_data;
 199
 200       if (is_ip6)
 201         {
 202           ip6_ext_header_t *prev = NULL;
 203           ah0 =
 204             ip6_ext_header_find (vm, b[0], ih6, IP_PROTOCOL_IPSEC_AH, &prev);
 205           pd->ip_hdr_size = sizeof (ip6_header_t);
 206           ASSERT ((u8 *) ah0 - (u8 *) ih6 == pd->ip_hdr_size);
 207         }
 208       else
 209         {
 210           if (ip4_is_fragment (ih4))
 211             {
 212               b[0]->error = node->errors[AH_DECRYPT_ERROR_DROP_FRAGMENTS];
 213               next[0] = AH_DECRYPT_NEXT_DROP;
 214               goto next;
 215             }
 216           pd->ip_hdr_size = ip4_header_bytes (ih4);
 217           ah0 = (ah_header_t *) ((u8 *) ih4 + pd->ip_hdr_size);
 218         }
 219
 220       pd->seq = clib_host_to_net_u32 (ah0->seq_no);
 221
 222       /* anti-replay check */
 223       if (ipsec_sa_anti_replay_check (sa0, pd->seq))
 224         {
 225           b[0]->error = node->errors[AH_DECRYPT_ERROR_REPLAY];
 226           next[0] = AH_DECRYPT_NEXT_DROP;
 227           goto next;
 228         }
 229
 230       current_sa_bytes += b[0]->current_length;
 231       current_sa_pkts += 1;
 232
 233       pd->icv_size = sa0->integ_icv_size;
 234       pd->nexthdr_cached = ah0->nexthdr;
 235       if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
 236         {
 237           if (PREDICT_FALSE (ipsec_sa_is_set_USE_ESN (sa0) &&
 238                              pd->current_data + b[0]->current_length
 239                              + sizeof (u32) > buffer_data_size))
 240             {
 241               b[0]->error = node->errors[AH_DECRYPT_ERROR_NO_TAIL_SPACE];
 242               next[0] = AH_DECRYPT_NEXT_DROP;
 243               goto next;
 244             }
 245
 246           vnet_crypto_op_t *op;
 247           vec_add2_aligned (ptd->integ_ops, op, 1, CLIB_CACHE_LINE_BYTES);
 248           vnet_crypto_op_init (op, sa0->integ_op_id);
 249
 250           op->src = (u8 *) ih4;
 251           op->len = b[0]->current_length;
 252           op->digest = (u8 *) ih4 - pd->icv_size;
 253           op->flags = VNET_CRYPTO_OP_FLAG_HMAC_CHECK;
 254           op->digest_len = pd->icv_size;
 255           op->key_index = sa0->integ_key_index;
 256           op->user_data = b - bufs;
 257           if (ipsec_sa_is_set_USE_ESN (sa0))
 258             {
 259               u32 seq_hi = clib_host_to_net_u32 (sa0->seq_hi);
 260
 261               op->len += sizeof (seq_hi);
 262               clib_memcpy (op->src + b[0]->current_length, &seq_hi,
 263                            sizeof (seq_hi));
 264             }
 265           clib_memcpy (op->digest, ah0->auth_data, pd->icv_size);
 266           clib_memset (ah0->auth_data, 0, pd->icv_size);
 267
 268           if (is_ip6)
 269             {
 270               pd->ip_version_traffic_class_and_flow_label =
 271                 ih6->ip_version_traffic_class_and_flow_label;
 272               pd->hop_limit = ih6->hop_limit;
 273               ih6->ip_version_traffic_class_and_flow_label = 0x60;
 274               ih6->hop_limit = 0;
 275               pd->nexthdr = ah0->nexthdr;
 276               pd->icv_padding_len =
 277                 ah_calc_icv_padding_len (pd->icv_size, 1 /* is_ipv6 */ );
 278             }
 279           else
 280             {
 281               pd->tos = ih4->tos;
 282               pd->ttl = ih4->ttl;
 283               ih4->tos = 0;
 284               ih4->ttl = 0;
 285               ih4->checksum = 0;
 286               pd->icv_padding_len =
 287                 ah_calc_icv_padding_len (pd->icv_size, 0 /* is_ipv6 */ );
 288             }
 289         }
 290
 291     next:
 292       n_left -= 1;
 293       pd += 1;
 294       next += 1;
 295       b += 1;
 296     }
 297
 298   n_left = from_frame->n_vectors;
 299   next = nexts;
 300   pd = pkt_data;
 301   b = bufs;
 302
 303   vlib_node_increment_counter (vm, node->node_index, AH_DECRYPT_ERROR_RX_PKTS,
 304                                n_left);
 305   vlib_increment_combined_counter (&ipsec_sa_counters, thread_index,
 306                                    current_sa_index, current_sa_pkts,
 307                                    current_sa_bytes);
 308
 309   ah_process_ops (vm, node, ptd->integ_ops, bufs, nexts);
 310
 311   while (n_left > 0)
 312     {
 313       ip4_header_t *oh4;
 314       ip6_header_t *oh6;
 315
 316       if (next[0] < AH_DECRYPT_N_NEXT)
 317         goto trace;
 318
 319       sa0 = vec_elt_at_index (im->sad, pd->sa_index);
 320
 321       if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
 322         {
 323           /* redo the anit-reply check. see esp_decrypt for details */
 324           if (ipsec_sa_anti_replay_check (sa0, pd->seq))
 325             {
 326               b[0]->error = node->errors[AH_DECRYPT_ERROR_REPLAY];
 327               next[0] = AH_DECRYPT_NEXT_DROP;
 328               goto trace;
 329             }
 330           ipsec_sa_anti_replay_advance (sa0, pd->seq);
 331         }
 332
 333       u16 ah_hdr_len = sizeof (ah_header_t) + pd->icv_size
 334         + pd->icv_padding_len;
 335       vlib_buffer_advance (b[0], pd->ip_hdr_size + ah_hdr_len);
 336       b[0]->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
 337
 338       if (PREDICT_TRUE (ipsec_sa_is_set_IS_TUNNEL (sa0)))
 339         {                       /* tunnel mode */
 340           if (PREDICT_TRUE (pd->nexthdr_cached == IP_PROTOCOL_IP_IN_IP))
 341             next[0] = AH_DECRYPT_NEXT_IP4_INPUT;
 342           else if (pd->nexthdr_cached == IP_PROTOCOL_IPV6)
 343             next[0] = AH_DECRYPT_NEXT_IP6_INPUT;
 344           else
 345             {
 346               b[0]->error = node->errors[AH_DECRYPT_ERROR_DECRYPTION_FAILED];
 347               next[0] = AH_DECRYPT_NEXT_DROP;
 348               goto trace;
 349             }
 350         }
 351       else
 352         {                       /* transport mode */
 353           if (is_ip6)
 354             {
 355               vlib_buffer_advance (b[0], -sizeof (ip6_header_t));
 356               oh6 = vlib_buffer_get_current (b[0]);
 357               if (ah_hdr_len >= sizeof (ip6_header_t))
 358                 clib_memcpy (oh6, b[0]->data + pd->current_data,
 359                              sizeof (ip6_header_t));
 360               else
 361                 memmove (oh6, b[0]->data + pd->current_data,
 362                          sizeof (ip6_header_t));
 363
 364               next[0] = AH_DECRYPT_NEXT_IP6_INPUT;
 365               oh6->protocol = pd->nexthdr;
 366               oh6->hop_limit = pd->hop_limit;
 367               oh6->ip_version_traffic_class_and_flow_label =
 368                 pd->ip_version_traffic_class_and_flow_label;
 369               oh6->payload_length =
 370                 clib_host_to_net_u16 (vlib_buffer_length_in_chain
 371                                       (vm, b[0]) - sizeof (ip6_header_t));
 372             }
 373           else
 374             {
 375               vlib_buffer_advance (b[0], -sizeof (ip4_header_t));
 376               oh4 = vlib_buffer_get_current (b[0]);
 377               if (ah_hdr_len >= sizeof (ip4_header_t))
 378                 clib_memcpy (oh4, b[0]->data + pd->current_data,
 379                              sizeof (ip4_header_t));
 380               else
 381                 memmove (oh4, b[0]->data + pd->current_data,
 382                          sizeof (ip4_header_t));
 383
 384               next[0] = AH_DECRYPT_NEXT_IP4_INPUT;
 385               oh4->ip_version_and_header_length = 0x45;
 386               oh4->fragment_id = 0;
 387               oh4->flags_and_fragment_offset = 0;
 388               oh4->protocol = pd->nexthdr_cached;
 389               oh4->length =
 390                 clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b[0]));
 391               oh4->ttl = pd->ttl;
 392               oh4->tos = pd->tos;
 393               oh4->checksum = ip4_header_checksum (oh4);
 394             }
 395         }
 396
 397       vnet_buffer (b[0])->sw_if_index[VLIB_TX] = (u32) ~ 0;
 398     trace:
 399       if (PREDICT_FALSE (b[0]->flags & VLIB_BUFFER_IS_TRACED))
 400         {
 401           sa0 = pool_elt_at_index (im->sad,
 402                                    vnet_buffer (b[0])->ipsec.sad_index);
 403           ah_decrypt_trace_t *tr =
 404             vlib_add_trace (vm, node, b[0], sizeof (*tr));
 405           tr->integ_alg = sa0->integ_alg;
 406           tr->seq_num = pd->seq;
 407         }
 408
 409       n_left -= 1;
 410       pd += 1;
 411       next += 1;
 412       b += 1;
 413     }
 414
 415   n_left = from_frame->n_vectors;
 416   vlib_buffer_enqueue_to_next (vm, node, from, nexts, n_left);
 417
 418   return n_left;
 419 }
 420
 421 VLIB_NODE_FN (ah4_decrypt_node) (vlib_main_t * vm,
 422                                  vlib_node_runtime_t * node,
 423                                  vlib_frame_t * from_frame)
 424 {
 425   return ah_decrypt_inline (vm, node, from_frame, 0 /* is_ip6 */ );
 426 }
 427
 428 /* *INDENT-OFF* */
 429 VLIB_REGISTER_NODE (ah4_decrypt_node) = {
 430   .name = "ah4-decrypt",
 431   .vector_size = sizeof (u32),
 432   .format_trace = format_ah_decrypt_trace,
 433   .type = VLIB_NODE_TYPE_INTERNAL,
 434
 435   .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
 436   .error_strings = ah_decrypt_error_strings,
 437
 438   .n_next_nodes = AH_DECRYPT_N_NEXT,
 439   .next_nodes = {
 440     [AH_DECRYPT_NEXT_DROP] = "ip4-drop",
 441     [AH_DECRYPT_NEXT_IP4_INPUT] = "ip4-input-no-checksum",
 442     [AH_DECRYPT_NEXT_IP6_INPUT] = "ip6-input",
 443     [AH_DECRYPT_NEXT_HANDOFF] = "ah4-decrypt-handoff",
 444   },
 445 };
 446 /* *INDENT-ON* */
 447
 448 VLIB_NODE_FN (ah6_decrypt_node) (vlib_main_t * vm,
 449                                  vlib_node_runtime_t * node,
 450                                  vlib_frame_t * from_frame)
 451 {
 452   return ah_decrypt_inline (vm, node, from_frame, 1 /* is_ip6 */ );
 453 }
 454
 455 /* *INDENT-OFF* */
 456 VLIB_REGISTER_NODE (ah6_decrypt_node) = {
 457   .name = "ah6-decrypt",
 458   .vector_size = sizeof (u32),
 459   .format_trace = format_ah_decrypt_trace,
 460   .type = VLIB_NODE_TYPE_INTERNAL,
 461
 462   .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
 463   .error_strings = ah_decrypt_error_strings,
 464
 465   .n_next_nodes = AH_DECRYPT_N_NEXT,
 466   .next_nodes = {
 467     [AH_DECRYPT_NEXT_DROP] = "ip6-drop",
 468     [AH_DECRYPT_NEXT_IP4_INPUT] = "ip4-input-no-checksum",
 469     [AH_DECRYPT_NEXT_IP6_INPUT] = "ip6-input",
 470     [AH_DECRYPT_NEXT_HANDOFF] = "ah6-decrypt-handoff",
 471   },
 472 };
 473 /* *INDENT-ON* */
 474
 475 /*
 476  * fd.io coding-style-patch-verification: ON
 477  *
 478  * Local Variables:
 479  * eval: (c-set-style "gnu")
 480  * End:
 481  */