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           ah0 =
 188             ip6_ext_header_find (vm, b[0], ih6, IP_PROTOCOL_IPSEC_AH, &prev);
 189           pd->ip_hdr_size = sizeof (ip6_header_t);
 190           ASSERT ((u8 *) ah0 - (u8 *) ih6 == pd->ip_hdr_size);
 191         }
 192       else
 193         {
 194           if (ip4_is_fragment (ih4))
 195             {
 196               b[0]->error = node->errors[AH_DECRYPT_ERROR_DROP_FRAGMENTS];
 197               next[0] = AH_DECRYPT_NEXT_DROP;
 198               goto next;
 199             }
 200           pd->ip_hdr_size = ip4_header_bytes (ih4);
 201           ah0 = (ah_header_t *) ((u8 *) ih4 + pd->ip_hdr_size);
 202         }
 203
 204       pd->seq = clib_host_to_net_u32 (ah0->seq_no);
 205
 206       /* anti-replay check */
 207       if (ipsec_sa_anti_replay_check (sa0, pd->seq))
 208         {
 209           b[0]->error = node->errors[AH_DECRYPT_ERROR_REPLAY];
 210           next[0] = AH_DECRYPT_NEXT_DROP;
 211           goto next;
 212         }
 213
 214       current_sa_bytes += b[0]->current_length;
 215       current_sa_pkts += 1;
 216
 217       pd->icv_size = sa0->integ_icv_size;
 218       pd->nexthdr_cached = ah0->nexthdr;
 219       if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
 220         {
 221           if (PREDICT_FALSE (ipsec_sa_is_set_USE_ESN (sa0) &&
 222                              pd->current_data + b[0]->current_length
 223                              + sizeof (u32) > buffer_data_size))
 224             {
 225               b[0]->error = node->errors[AH_DECRYPT_ERROR_NO_TAIL_SPACE];
 226               next[0] = AH_DECRYPT_NEXT_DROP;
 227               goto next;
 228             }
 229
 230           vnet_crypto_op_t *op;
 231           vec_add2_aligned (ptd->integ_ops, op, 1, CLIB_CACHE_LINE_BYTES);
 232           vnet_crypto_op_init (op, sa0->integ_op_id);
 233
 234           op->src = (u8 *) ih4;
 235           op->len = b[0]->current_length;
 236           op->digest = (u8 *) ih4 - pd->icv_size;
 237           op->flags = VNET_CRYPTO_OP_FLAG_HMAC_CHECK;
 238           op->digest_len = pd->icv_size;
 239           op->key_index = sa0->integ_key_index;
 240           op->user_data = b - bufs;
 241           if (ipsec_sa_is_set_USE_ESN (sa0))
 242             {
 243               u32 seq_hi = clib_host_to_net_u32 (sa0->seq_hi);
 244
 245               op->len += sizeof (seq_hi);
 246               clib_memcpy (op->src + b[0]->current_length, &seq_hi,
 247                            sizeof (seq_hi));
 248             }
 249           clib_memcpy (op->digest, ah0->auth_data, pd->icv_size);
 250           clib_memset (ah0->auth_data, 0, pd->icv_size);
 251
 252           if (is_ip6)
 253             {
 254               pd->ip_version_traffic_class_and_flow_label =
 255                 ih6->ip_version_traffic_class_and_flow_label;
 256               pd->hop_limit = ih6->hop_limit;
 257               ih6->ip_version_traffic_class_and_flow_label = 0x60;
 258               ih6->hop_limit = 0;
 259               pd->nexthdr = ah0->nexthdr;
 260               pd->icv_padding_len =
 261                 ah_calc_icv_padding_len (pd->icv_size, 1 /* is_ipv6 */ );
 262             }
 263           else
 264             {
 265               pd->tos = ih4->tos;
 266               pd->ttl = ih4->ttl;
 267               ih4->tos = 0;
 268               ih4->ttl = 0;
 269               ih4->checksum = 0;
 270               pd->icv_padding_len =
 271                 ah_calc_icv_padding_len (pd->icv_size, 0 /* is_ipv6 */ );
 272             }
 273         }
 274
 275     next:
 276       n_left -= 1;
 277       pd += 1;
 278       next += 1;
 279       b += 1;
 280     }
 281
 282   n_left = from_frame->n_vectors;
 283   next = nexts;
 284   pd = pkt_data;
 285   b = bufs;
 286
 287   vlib_node_increment_counter (vm, node->node_index, AH_DECRYPT_ERROR_RX_PKTS,
 288                                n_left);
 289   vlib_increment_combined_counter (&ipsec_sa_counters, thread_index,
 290                                    current_sa_index, current_sa_pkts,
 291                                    current_sa_bytes);
 292
 293   ah_process_ops (vm, node, ptd->integ_ops, bufs, nexts);
 294
 295   while (n_left > 0)
 296     {
 297       ip4_header_t *oh4;
 298       ip6_header_t *oh6;
 299
 300       if (next[0] < AH_DECRYPT_N_NEXT)
 301         goto trace;
 302
 303       sa0 = vec_elt_at_index (im->sad, pd->sa_index);
 304
 305       if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
 306         {
 307           /* redo the anit-reply check. see esp_decrypt for details */
 308           if (ipsec_sa_anti_replay_check (sa0, pd->seq))
 309             {
 310               b[0]->error = node->errors[AH_DECRYPT_ERROR_REPLAY];
 311               next[0] = AH_DECRYPT_NEXT_DROP;
 312               goto trace;
 313             }
 314           ipsec_sa_anti_replay_advance (sa0, pd->seq);
 315         }
 316
 317       u16 ah_hdr_len = sizeof (ah_header_t) + pd->icv_size
 318         + pd->icv_padding_len;
 319       vlib_buffer_advance (b[0], pd->ip_hdr_size + ah_hdr_len);
 320       b[0]->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
 321
 322       if (PREDICT_TRUE (ipsec_sa_is_set_IS_TUNNEL (sa0)))
 323         {                       /* tunnel mode */
 324           if (PREDICT_TRUE (pd->nexthdr_cached == IP_PROTOCOL_IP_IN_IP))
 325             next[0] = AH_DECRYPT_NEXT_IP4_INPUT;
 326           else if (pd->nexthdr_cached == IP_PROTOCOL_IPV6)
 327             next[0] = AH_DECRYPT_NEXT_IP6_INPUT;
 328           else
 329             {
 330               b[0]->error = node->errors[AH_DECRYPT_ERROR_DECRYPTION_FAILED];
 331               next[0] = AH_DECRYPT_NEXT_DROP;
 332               goto trace;
 333             }
 334         }
 335       else
 336         {                       /* transport mode */
 337           if (is_ip6)
 338             {
 339               vlib_buffer_advance (b[0], -sizeof (ip6_header_t));
 340               oh6 = vlib_buffer_get_current (b[0]);
 341               if (ah_hdr_len >= sizeof (ip6_header_t))
 342                 clib_memcpy (oh6, b[0]->data + pd->current_data,
 343                              sizeof (ip6_header_t));
 344               else
 345                 memmove (oh6, b[0]->data + pd->current_data,
 346                          sizeof (ip6_header_t));
 347
 348               next[0] = AH_DECRYPT_NEXT_IP6_INPUT;
 349               oh6->protocol = pd->nexthdr;
 350               oh6->hop_limit = pd->hop_limit;
 351               oh6->ip_version_traffic_class_and_flow_label =
 352                 pd->ip_version_traffic_class_and_flow_label;
 353               oh6->payload_length =
 354                 clib_host_to_net_u16 (vlib_buffer_length_in_chain
 355                                       (vm, b[0]) - sizeof (ip6_header_t));
 356             }
 357           else
 358             {
 359               vlib_buffer_advance (b[0], -sizeof (ip4_header_t));
 360               oh4 = vlib_buffer_get_current (b[0]);
 361               if (ah_hdr_len >= sizeof (ip4_header_t))
 362                 clib_memcpy (oh4, b[0]->data + pd->current_data,
 363                              sizeof (ip4_header_t));
 364               else
 365                 memmove (oh4, b[0]->data + pd->current_data,
 366                          sizeof (ip4_header_t));
 367
 368               next[0] = AH_DECRYPT_NEXT_IP4_INPUT;
 369               oh4->ip_version_and_header_length = 0x45;
 370               oh4->fragment_id = 0;
 371               oh4->flags_and_fragment_offset = 0;
 372               oh4->protocol = pd->nexthdr_cached;
 373               oh4->length =
 374                 clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b[0]));
 375               oh4->ttl = pd->ttl;
 376               oh4->tos = pd->tos;
 377               oh4->checksum = ip4_header_checksum (oh4);
 378             }
 379         }
 380
 381       vnet_buffer (b[0])->sw_if_index[VLIB_TX] = (u32) ~ 0;
 382     trace:
 383       if (PREDICT_FALSE (b[0]->flags & VLIB_BUFFER_IS_TRACED))
 384         {
 385           sa0 = pool_elt_at_index (im->sad,
 386                                    vnet_buffer (b[0])->ipsec.sad_index);
 387           ah_decrypt_trace_t *tr =
 388             vlib_add_trace (vm, node, b[0], sizeof (*tr));
 389           tr->integ_alg = sa0->integ_alg;
 390           tr->seq_num = pd->seq;
 391         }
 392
 393       n_left -= 1;
 394       pd += 1;
 395       next += 1;
 396       b += 1;
 397     }
 398
 399   n_left = from_frame->n_vectors;
 400   vlib_buffer_enqueue_to_next (vm, node, from, nexts, n_left);
 401
 402   return n_left;
 403 }
 404
 405 VLIB_NODE_FN (ah4_decrypt_node) (vlib_main_t * vm,
 406                                  vlib_node_runtime_t * node,
 407                                  vlib_frame_t * from_frame)
 408 {
 409   return ah_decrypt_inline (vm, node, from_frame, 0 /* is_ip6 */ );
 410 }
 411
 412 /* *INDENT-OFF* */
 413 VLIB_REGISTER_NODE (ah4_decrypt_node) = {
 414   .name = "ah4-decrypt",
 415   .vector_size = sizeof (u32),
 416   .format_trace = format_ah_decrypt_trace,
 417   .type = VLIB_NODE_TYPE_INTERNAL,
 418
 419   .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
 420   .error_strings = ah_decrypt_error_strings,
 421
 422   .n_next_nodes = AH_DECRYPT_N_NEXT,
 423   .next_nodes = {
 424 #define _(s,n) [AH_DECRYPT_NEXT_##s] = n,
 425     foreach_ah_decrypt_next
 426 #undef _
 427   },
 428 };
 429 /* *INDENT-ON* */
 430
 431 VLIB_NODE_FN (ah6_decrypt_node) (vlib_main_t * vm,
 432                                  vlib_node_runtime_t * node,
 433                                  vlib_frame_t * from_frame)
 434 {
 435   return ah_decrypt_inline (vm, node, from_frame, 1 /* is_ip6 */ );
 436 }
 437
 438 /* *INDENT-OFF* */
 439 VLIB_REGISTER_NODE (ah6_decrypt_node) = {
 440   .name = "ah6-decrypt",
 441   .vector_size = sizeof (u32),
 442   .format_trace = format_ah_decrypt_trace,
 443   .type = VLIB_NODE_TYPE_INTERNAL,
 444
 445   .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
 446   .error_strings = ah_decrypt_error_strings,
 447
 448   .n_next_nodes = AH_DECRYPT_N_NEXT,
 449   .next_nodes = {
 450 #define _(s,n) [AH_DECRYPT_NEXT_##s] = n,
 451     foreach_ah_decrypt_next
 452 #undef _
 453   },
 454 };
 455 /* *INDENT-ON* */
 456
 457 /*
 458  * fd.io coding-style-patch-verification: ON
 459  *
 460  * Local Variables:
 461  * eval: (c-set-style "gnu")
 462  * End:
 463  */