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   _ (IPSEC_GRE_INPUT, "ipsec-gre-input")
  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   _ (REPLAY, "SA replayed packet")
  46
  47 typedef enum
  48 {
  49 #define _(sym,str) AH_DECRYPT_ERROR_##sym,
  50   foreach_ah_decrypt_error
  51 #undef _
  52     AH_DECRYPT_N_ERROR,
  53 } ah_decrypt_error_t;
  54
  55 static char *ah_decrypt_error_strings[] = {
  56 #define _(sym,string) string,
  57   foreach_ah_decrypt_error
  58 #undef _
  59 };
  60
  61 typedef struct
  62 {
  63   ipsec_integ_alg_t integ_alg;
  64   u32 seq_num;
  65 } ah_decrypt_trace_t;
  66
  67 /* packet trace format function */
  68 static u8 *
  69 format_ah_decrypt_trace (u8 * s, va_list * args)
  70 {
  71   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  72   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  73   ah_decrypt_trace_t *t = va_arg (*args, ah_decrypt_trace_t *);
  74
  75   s = format (s, "ah: integrity %U seq-num %d",
  76               format_ipsec_integ_alg, t->integ_alg, t->seq_num);
  77   return s;
  78 }
  79
  80 always_inline uword
  81 ah_decrypt_inline (vlib_main_t * vm,
  82                    vlib_node_runtime_t * node, vlib_frame_t * from_frame,
  83                    int is_ip6)
  84 {
  85   u32 n_left_from, *from, next_index, *to_next, thread_index;
  86   ipsec_main_t *im = &ipsec_main;
  87   ipsec_proto_main_t *em = &ipsec_proto_main;
  88   from = vlib_frame_vector_args (from_frame);
  89   n_left_from = from_frame->n_vectors;
  90   int icv_size = 0;
  91
  92   next_index = node->cached_next_index;
  93   thread_index = vm->thread_index;
  94
  95   while (n_left_from > 0)
  96     {
  97       u32 n_left_to_next;
  98
  99       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
 100
 101       while (n_left_from > 0 && n_left_to_next > 0)
 102         {
 103           u32 i_bi0;
 104           u32 next0;
 105           vlib_buffer_t *i_b0;
 106           ah_header_t *ah0;
 107           ipsec_sa_t *sa0;
 108           u32 sa_index0 = ~0;
 109           u32 seq;
 110           ip4_header_t *ih4 = 0, *oh4 = 0;
 111           ip6_header_t *ih6 = 0, *oh6 = 0;
 112           u8 ip_hdr_size = 0;
 113           u8 tos = 0;
 114           u8 ttl = 0;
 115           u32 ip_version_traffic_class_and_flow_label = 0;
 116           u8 hop_limit = 0;
 117           u8 nexthdr = 0;
 118           u8 icv_padding_len = 0;
 119
 120
 121           i_bi0 = from[0];
 122           from += 1;
 123           n_left_from -= 1;
 124           n_left_to_next -= 1;
 125
 126           next0 = AH_DECRYPT_NEXT_DROP;
 127
 128           i_b0 = vlib_get_buffer (vm, i_bi0);
 129           to_next[0] = i_bi0;
 130           to_next += 1;
 131           ih4 = vlib_buffer_get_current (i_b0);
 132           ih6 = vlib_buffer_get_current (i_b0);
 133           sa_index0 = vnet_buffer (i_b0)->ipsec.sad_index;
 134           sa0 = pool_elt_at_index (im->sad, sa_index0);
 135
 136           vlib_prefetch_combined_counter (&ipsec_sa_counters,
 137                                           thread_index, sa_index0);
 138
 139           if (is_ip6)
 140             {
 141               ip6_ext_header_t *prev = NULL;
 142               ip6_ext_header_find_t (ih6, prev, ah0, IP_PROTOCOL_IPSEC_AH);
 143               ip_hdr_size = sizeof (ip6_header_t);
 144               ASSERT ((u8 *) ah0 - (u8 *) ih6 == ip_hdr_size);
 145             }
 146           else
 147             {
 148               ip_hdr_size = ip4_header_bytes (ih4);
 149               ah0 = (ah_header_t *) ((u8 *) ih4 + ip_hdr_size);
 150             }
 151
 152           seq = clib_host_to_net_u32 (ah0->seq_no);
 153
 154           /* anti-replay check */
 155           if (sa0->use_anti_replay)
 156             {
 157               int rv = 0;
 158
 159               if (PREDICT_TRUE (sa0->use_esn))
 160                 rv = esp_replay_check_esn (sa0, seq);
 161               else
 162                 rv = esp_replay_check (sa0, seq);
 163
 164               if (PREDICT_FALSE (rv))
 165                 {
 166                   vlib_node_increment_counter (vm, node->node_index,
 167                                                AH_DECRYPT_ERROR_REPLAY, 1);
 168                   goto trace;
 169                 }
 170             }
 171
 172           vlib_increment_combined_counter
 173             (&ipsec_sa_counters, thread_index, sa_index0,
 174              1, i_b0->current_length);
 175
 176           icv_size =
 177             em->ipsec_proto_main_integ_algs[sa0->integ_alg].trunc_size;
 178           if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
 179             {
 180               u8 sig[64];
 181               u8 digest[64];
 182               clib_memset (sig, 0, sizeof (sig));
 183               clib_memset (digest, 0, sizeof (digest));
 184               u8 *icv = ah0->auth_data;
 185               memcpy (digest, icv, icv_size);
 186               clib_memset (icv, 0, icv_size);
 187
 188               if (is_ip6)
 189                 {
 190                   ip_version_traffic_class_and_flow_label =
 191                     ih6->ip_version_traffic_class_and_flow_label;
 192                   hop_limit = ih6->hop_limit;
 193                   ih6->ip_version_traffic_class_and_flow_label = 0x60;
 194                   ih6->hop_limit = 0;
 195                   nexthdr = ah0->nexthdr;
 196                   icv_padding_len =
 197                     ah_calc_icv_padding_len (icv_size, 1 /* is_ipv6 */ );
 198                 }
 199               else
 200                 {
 201                   tos = ih4->tos;
 202                   ttl = ih4->ttl;
 203                   ih4->tos = 0;
 204                   ih4->ttl = 0;
 205                   ih4->checksum = 0;
 206                   ih4->flags_and_fragment_offset = 0;
 207                   icv_padding_len =
 208                     ah_calc_icv_padding_len (icv_size, 0 /* is_ipv6 */ );
 209                 }
 210               hmac_calc (sa0->integ_alg, sa0->integ_key.data,
 211                          sa0->integ_key.len, (u8 *) ih4, i_b0->current_length,
 212                          sig, sa0->use_esn, sa0->seq_hi);
 213
 214               if (PREDICT_FALSE (memcmp (digest, sig, icv_size)))
 215                 {
 216                   vlib_node_increment_counter (vm, node->node_index,
 217                                                AH_DECRYPT_ERROR_INTEG_ERROR,
 218                                                1);
 219                   goto trace;
 220                 }
 221
 222               if (PREDICT_TRUE (sa0->use_anti_replay))
 223                 {
 224                   if (PREDICT_TRUE (sa0->use_esn))
 225                     esp_replay_advance_esn (sa0, seq);
 226                   else
 227                     esp_replay_advance (sa0, seq);
 228                 }
 229
 230             }
 231
 232           vlib_buffer_advance (i_b0,
 233                                ip_hdr_size + sizeof (ah_header_t) + icv_size +
 234                                icv_padding_len);
 235           i_b0->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
 236
 237           if (PREDICT_TRUE (sa0->is_tunnel))
 238             {                   /* tunnel mode */
 239               if (PREDICT_TRUE (ah0->nexthdr == IP_PROTOCOL_IP_IN_IP))
 240                 next0 = AH_DECRYPT_NEXT_IP4_INPUT;
 241               else if (ah0->nexthdr == IP_PROTOCOL_IPV6)
 242                 next0 = AH_DECRYPT_NEXT_IP6_INPUT;
 243               else
 244                 {
 245                   vlib_node_increment_counter (vm, node->node_index,
 246                                                AH_DECRYPT_ERROR_DECRYPTION_FAILED,
 247                                                1);
 248                   goto trace;
 249                 }
 250             }
 251           else
 252             {                   /* transport mode */
 253               if (is_ip6)
 254                 {
 255                   vlib_buffer_advance (i_b0, -sizeof (ip6_header_t));
 256                   oh6 = vlib_buffer_get_current (i_b0);
 257                   memmove (oh6, ih6, sizeof (ip6_header_t));
 258
 259                   next0 = AH_DECRYPT_NEXT_IP6_INPUT;
 260                   oh6->protocol = nexthdr;
 261                   oh6->hop_limit = hop_limit;
 262                   oh6->ip_version_traffic_class_and_flow_label =
 263                     ip_version_traffic_class_and_flow_label;
 264                   oh6->payload_length =
 265                     clib_host_to_net_u16 (vlib_buffer_length_in_chain
 266                                           (vm, i_b0) - sizeof (ip6_header_t));
 267                 }
 268               else
 269                 {
 270                   vlib_buffer_advance (i_b0, -sizeof (ip4_header_t));
 271                   oh4 = vlib_buffer_get_current (i_b0);
 272                   memmove (oh4, ih4, sizeof (ip4_header_t));
 273
 274                   next0 = AH_DECRYPT_NEXT_IP4_INPUT;
 275                   oh4->ip_version_and_header_length = 0x45;
 276                   oh4->fragment_id = 0;
 277                   oh4->flags_and_fragment_offset = 0;
 278                   oh4->protocol = ah0->nexthdr;
 279                   oh4->length =
 280                     clib_host_to_net_u16 (vlib_buffer_length_in_chain
 281                                           (vm, i_b0));
 282                   oh4->ttl = ttl;
 283                   oh4->tos = tos;
 284                   oh4->checksum = ip4_header_checksum (oh4);
 285                 }
 286             }
 287
 288           /* for IPSec-GRE tunnel next node is ipsec-gre-input */
 289           if (PREDICT_FALSE
 290               ((vnet_buffer (i_b0)->ipsec.flags) &
 291                IPSEC_FLAG_IPSEC_GRE_TUNNEL))
 292             next0 = AH_DECRYPT_NEXT_IPSEC_GRE_INPUT;
 293
 294
 295           vnet_buffer (i_b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
 296         trace:
 297           if (PREDICT_FALSE (i_b0->flags & VLIB_BUFFER_IS_TRACED))
 298             {
 299               i_b0->flags |= VLIB_BUFFER_IS_TRACED;
 300               ah_decrypt_trace_t *tr =
 301                 vlib_add_trace (vm, node, i_b0, sizeof (*tr));
 302               tr->integ_alg = sa0->integ_alg;
 303               tr->seq_num = seq;
 304             }
 305           vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
 306                                            n_left_to_next, i_bi0, next0);
 307         }
 308       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
 309     }
 310   vlib_node_increment_counter (vm, node->node_index, AH_DECRYPT_ERROR_RX_PKTS,
 311                                from_frame->n_vectors);
 312
 313   return from_frame->n_vectors;
 314 }
 315
 316 VLIB_NODE_FN (ah4_decrypt_node) (vlib_main_t * vm,
 317                                  vlib_node_runtime_t * node,
 318                                  vlib_frame_t * from_frame)
 319 {
 320   return ah_decrypt_inline (vm, node, from_frame, 0 /* is_ip6 */ );
 321 }
 322
 323 /* *INDENT-OFF* */
 324 VLIB_REGISTER_NODE (ah4_decrypt_node) = {
 325   .name = "ah4-decrypt",
 326   .vector_size = sizeof (u32),
 327   .format_trace = format_ah_decrypt_trace,
 328   .type = VLIB_NODE_TYPE_INTERNAL,
 329
 330   .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
 331   .error_strings = ah_decrypt_error_strings,
 332
 333   .n_next_nodes = AH_DECRYPT_N_NEXT,
 334   .next_nodes = {
 335 #define _(s,n) [AH_DECRYPT_NEXT_##s] = n,
 336     foreach_ah_decrypt_next
 337 #undef _
 338   },
 339 };
 340 /* *INDENT-ON* */
 341
 342 VLIB_NODE_FN (ah6_decrypt_node) (vlib_main_t * vm,
 343                                  vlib_node_runtime_t * node,
 344                                  vlib_frame_t * from_frame)
 345 {
 346   return ah_decrypt_inline (vm, node, from_frame, 1 /* is_ip6 */ );
 347 }
 348
 349 /* *INDENT-OFF* */
 350 VLIB_REGISTER_NODE (ah6_decrypt_node) = {
 351   .name = "ah6-decrypt",
 352   .vector_size = sizeof (u32),
 353   .format_trace = format_ah_decrypt_trace,
 354   .type = VLIB_NODE_TYPE_INTERNAL,
 355
 356   .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
 357   .error_strings = ah_decrypt_error_strings,
 358
 359   .n_next_nodes = AH_DECRYPT_N_NEXT,
 360   .next_nodes = {
 361 #define _(s,n) [AH_DECRYPT_NEXT_##s] = n,
 362     foreach_ah_decrypt_next
 363 #undef _
 364   },
 365 };
 366 /* *INDENT-ON* */
 367
 368 /*
 369  * fd.io coding-style-patch-verification: ON
 370  *
 371  * Local Variables:
 372  * eval: (c-set-style "gnu")
 373  * End:
 374  */