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
  26 #define foreach_ah_decrypt_next \
  27   _ (DROP, "error-drop")        \
  28   _ (IP4_INPUT, "ip4-input")    \
  29   _ (IP6_INPUT, "ip6-input")    \
  30   _ (IPSEC_GRE_INPUT, "ipsec-gre-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   _ (REPLAY, "SA replayed packet")
  45
  46 typedef enum
  47 {
  48 #define _(sym,str) AH_DECRYPT_ERROR_##sym,
  49   foreach_ah_decrypt_error
  50 #undef _
  51     AH_DECRYPT_N_ERROR,
  52 } ah_decrypt_error_t;
  53
  54 static char *ah_decrypt_error_strings[] = {
  55 #define _(sym,string) string,
  56   foreach_ah_decrypt_error
  57 #undef _
  58 };
  59
  60 typedef struct
  61 {
  62   ipsec_integ_alg_t integ_alg;
  63   u32 seq_num;
  64 } ah_decrypt_trace_t;
  65
  66 /* packet trace format function */
  67 static u8 *
  68 format_ah_decrypt_trace (u8 * s, va_list * args)
  69 {
  70   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  71   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  72   ah_decrypt_trace_t *t = va_arg (*args, ah_decrypt_trace_t *);
  73
  74   s = format (s, "ah: integrity %U seq-num %d",
  75               format_ipsec_integ_alg, t->integ_alg, t->seq_num);
  76   return s;
  77 }
  78
  79 always_inline uword
  80 ah_decrypt_inline (vlib_main_t * vm,
  81                    vlib_node_runtime_t * node, vlib_frame_t * from_frame,
  82                    int is_ip6)
  83 {
  84   u32 n_left_from, *from, next_index, *to_next, thread_index;
  85   ipsec_main_t *im = &ipsec_main;
  86   ipsec_proto_main_t *em = &ipsec_proto_main;
  87   from = vlib_frame_vector_args (from_frame);
  88   n_left_from = from_frame->n_vectors;
  89   int icv_size = 0;
  90
  91   next_index = node->cached_next_index;
  92   thread_index = vm->thread_index;
  93
  94   while (n_left_from > 0)
  95     {
  96       u32 n_left_to_next;
  97
  98       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
  99
 100       while (n_left_from > 0 && n_left_to_next > 0)
 101         {
 102           u32 i_bi0;
 103           u32 next0;
 104           vlib_buffer_t *i_b0;
 105           ah_header_t *ah0;
 106           ipsec_sa_t *sa0;
 107           u32 sa_index0 = ~0;
 108           u32 seq;
 109           ip4_header_t *ih4 = 0, *oh4 = 0;
 110           ip6_header_t *ih6 = 0, *oh6 = 0;
 111           u8 ip_hdr_size = 0;
 112           u8 tos = 0;
 113           u8 ttl = 0;
 114           u32 ip_version_traffic_class_and_flow_label = 0;
 115           u8 hop_limit = 0;
 116           u8 nexthdr = 0;
 117           u8 icv_padding_len = 0;
 118
 119
 120           i_bi0 = from[0];
 121           from += 1;
 122           n_left_from -= 1;
 123           n_left_to_next -= 1;
 124
 125           next0 = AH_DECRYPT_NEXT_DROP;
 126
 127           i_b0 = vlib_get_buffer (vm, i_bi0);
 128           to_next[0] = i_bi0;
 129           to_next += 1;
 130           ih4 = vlib_buffer_get_current (i_b0);
 131           ih6 = vlib_buffer_get_current (i_b0);
 132           sa_index0 = vnet_buffer (i_b0)->ipsec.sad_index;
 133           sa0 = pool_elt_at_index (im->sad, sa_index0);
 134
 135           vlib_prefetch_combined_counter (&ipsec_sa_counters,
 136                                           thread_index, sa_index0);
 137
 138           if (is_ip6)
 139             {
 140               ip6_ext_header_t *prev = NULL;
 141               ip6_ext_header_find_t (ih6, prev, ah0, IP_PROTOCOL_IPSEC_AH);
 142               ip_hdr_size = sizeof (ip6_header_t);
 143               ASSERT ((u8 *) ah0 - (u8 *) ih6 == ip_hdr_size);
 144             }
 145           else
 146             {
 147               ip_hdr_size = ip4_header_bytes (ih4);
 148               ah0 = (ah_header_t *) ((u8 *) ih4 + ip_hdr_size);
 149             }
 150
 151           seq = clib_host_to_net_u32 (ah0->seq_no);
 152
 153           /* anti-replay check */
 154           if (sa0->use_anti_replay)
 155             {
 156               int rv = 0;
 157
 158               if (PREDICT_TRUE (sa0->use_esn))
 159                 rv = esp_replay_check_esn (sa0, seq);
 160               else
 161                 rv = esp_replay_check (sa0, seq);
 162
 163               if (PREDICT_FALSE (rv))
 164                 {
 165                   vlib_node_increment_counter (vm, node->node_index,
 166                                                AH_DECRYPT_ERROR_REPLAY, 1);
 167                   goto trace;
 168                 }
 169             }
 170
 171           vlib_increment_combined_counter
 172             (&ipsec_sa_counters, thread_index, sa_index0,
 173              1, i_b0->current_length);
 174
 175           icv_size =
 176             em->ipsec_proto_main_integ_algs[sa0->integ_alg].trunc_size;
 177           if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
 178             {
 179               u8 sig[64];
 180               u8 digest[64];
 181               clib_memset (sig, 0, sizeof (sig));
 182               clib_memset (digest, 0, sizeof (digest));
 183               u8 *icv = ah0->auth_data;
 184               memcpy (digest, icv, icv_size);
 185               clib_memset (icv, 0, icv_size);
 186
 187               if (is_ip6)
 188                 {
 189                   ip_version_traffic_class_and_flow_label =
 190                     ih6->ip_version_traffic_class_and_flow_label;
 191                   hop_limit = ih6->hop_limit;
 192                   ih6->ip_version_traffic_class_and_flow_label = 0x60;
 193                   ih6->hop_limit = 0;
 194                   nexthdr = ah0->nexthdr;
 195                   icv_padding_len =
 196                     ah_calc_icv_padding_len (icv_size, 1 /* is_ipv6 */ );
 197                 }
 198               else
 199                 {
 200                   tos = ih4->tos;
 201                   ttl = ih4->ttl;
 202                   ih4->tos = 0;
 203                   ih4->ttl = 0;
 204                   ih4->checksum = 0;
 205                   ih4->flags_and_fragment_offset = 0;
 206                   icv_padding_len =
 207                     ah_calc_icv_padding_len (icv_size, 0 /* is_ipv6 */ );
 208                 }
 209               hmac_calc (sa0->integ_alg, sa0->integ_key.data,
 210                          sa0->integ_key.len, (u8 *) ih4, i_b0->current_length,
 211                          sig, sa0->use_esn, sa0->seq_hi);
 212
 213               if (PREDICT_FALSE (memcmp (digest, sig, icv_size)))
 214                 {
 215                   vlib_node_increment_counter (vm, node->node_index,
 216                                                AH_DECRYPT_ERROR_INTEG_ERROR,
 217                                                1);
 218                   goto trace;
 219                 }
 220
 221               if (PREDICT_TRUE (sa0->use_anti_replay))
 222                 {
 223                   if (PREDICT_TRUE (sa0->use_esn))
 224                     esp_replay_advance_esn (sa0, seq);
 225                   else
 226                     esp_replay_advance (sa0, seq);
 227                 }
 228
 229             }
 230
 231           vlib_buffer_advance (i_b0,
 232                                ip_hdr_size + sizeof (ah_header_t) + icv_size +
 233                                icv_padding_len);
 234           i_b0->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
 235
 236           if (PREDICT_TRUE (sa0->is_tunnel))
 237             {                   /* tunnel mode */
 238               if (PREDICT_TRUE (ah0->nexthdr == IP_PROTOCOL_IP_IN_IP))
 239                 next0 = AH_DECRYPT_NEXT_IP4_INPUT;
 240               else if (ah0->nexthdr == IP_PROTOCOL_IPV6)
 241                 next0 = AH_DECRYPT_NEXT_IP6_INPUT;
 242               else
 243                 {
 244                   vlib_node_increment_counter (vm, node->node_index,
 245                                                AH_DECRYPT_ERROR_DECRYPTION_FAILED,
 246                                                1);
 247                   goto trace;
 248                 }
 249             }
 250           else
 251             {                   /* transport mode */
 252               if (is_ip6)
 253                 {
 254                   vlib_buffer_advance (i_b0, -sizeof (ip6_header_t));
 255                   oh6 = vlib_buffer_get_current (i_b0);
 256                   memmove (oh6, ih6, sizeof (ip6_header_t));
 257
 258                   next0 = AH_DECRYPT_NEXT_IP6_INPUT;
 259                   oh6->protocol = nexthdr;
 260                   oh6->hop_limit = hop_limit;
 261                   oh6->ip_version_traffic_class_and_flow_label =
 262                     ip_version_traffic_class_and_flow_label;
 263                   oh6->payload_length =
 264                     clib_host_to_net_u16 (vlib_buffer_length_in_chain
 265                                           (vm, i_b0) - sizeof (ip6_header_t));
 266                 }
 267               else
 268                 {
 269                   vlib_buffer_advance (i_b0, -sizeof (ip4_header_t));
 270                   oh4 = vlib_buffer_get_current (i_b0);
 271                   memmove (oh4, ih4, sizeof (ip4_header_t));
 272
 273                   next0 = AH_DECRYPT_NEXT_IP4_INPUT;
 274                   oh4->ip_version_and_header_length = 0x45;
 275                   oh4->fragment_id = 0;
 276                   oh4->flags_and_fragment_offset = 0;
 277                   oh4->protocol = ah0->nexthdr;
 278                   oh4->length =
 279                     clib_host_to_net_u16 (vlib_buffer_length_in_chain
 280                                           (vm, i_b0));
 281                   oh4->ttl = ttl;
 282                   oh4->tos = tos;
 283                   oh4->checksum = ip4_header_checksum (oh4);
 284                 }
 285             }
 286
 287           /* for IPSec-GRE tunnel next node is ipsec-gre-input */
 288           if (PREDICT_FALSE
 289               ((vnet_buffer (i_b0)->ipsec.flags) &
 290                IPSEC_FLAG_IPSEC_GRE_TUNNEL))
 291             next0 = AH_DECRYPT_NEXT_IPSEC_GRE_INPUT;
 292
 293
 294           vnet_buffer (i_b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
 295         trace:
 296           if (PREDICT_FALSE (i_b0->flags & VLIB_BUFFER_IS_TRACED))
 297             {
 298               i_b0->flags |= VLIB_BUFFER_IS_TRACED;
 299               ah_decrypt_trace_t *tr =
 300                 vlib_add_trace (vm, node, i_b0, sizeof (*tr));
 301               tr->integ_alg = sa0->integ_alg;
 302               tr->seq_num = seq;
 303             }
 304           vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
 305                                            n_left_to_next, i_bi0, next0);
 306         }
 307       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
 308     }
 309   vlib_node_increment_counter (vm, node->node_index, AH_DECRYPT_ERROR_RX_PKTS,
 310                                from_frame->n_vectors);
 311
 312   return from_frame->n_vectors;
 313 }
 314
 315 VLIB_NODE_FN (ah4_decrypt_node) (vlib_main_t * vm,
 316                                  vlib_node_runtime_t * node,
 317                                  vlib_frame_t * from_frame)
 318 {
 319   return ah_decrypt_inline (vm, node, from_frame, 0 /* is_ip6 */ );
 320 }
 321
 322 /* *INDENT-OFF* */
 323 VLIB_REGISTER_NODE (ah4_decrypt_node) = {
 324   .name = "ah4-decrypt",
 325   .vector_size = sizeof (u32),
 326   .format_trace = format_ah_decrypt_trace,
 327   .type = VLIB_NODE_TYPE_INTERNAL,
 328
 329   .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
 330   .error_strings = ah_decrypt_error_strings,
 331
 332   .n_next_nodes = AH_DECRYPT_N_NEXT,
 333   .next_nodes = {
 334 #define _(s,n) [AH_DECRYPT_NEXT_##s] = n,
 335     foreach_ah_decrypt_next
 336 #undef _
 337   },
 338 };
 339 /* *INDENT-ON* */
 340
 341 VLIB_NODE_FN (ah6_decrypt_node) (vlib_main_t * vm,
 342                                  vlib_node_runtime_t * node,
 343                                  vlib_frame_t * from_frame)
 344 {
 345   return ah_decrypt_inline (vm, node, from_frame, 1 /* is_ip6 */ );
 346 }
 347
 348 /* *INDENT-OFF* */
 349 VLIB_REGISTER_NODE (ah6_decrypt_node) = {
 350   .name = "ah6-decrypt",
 351   .vector_size = sizeof (u32),
 352   .format_trace = format_ah_decrypt_trace,
 353   .type = VLIB_NODE_TYPE_INTERNAL,
 354
 355   .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
 356   .error_strings = ah_decrypt_error_strings,
 357
 358   .n_next_nodes = AH_DECRYPT_N_NEXT,
 359   .next_nodes = {
 360 #define _(s,n) [AH_DECRYPT_NEXT_##s] = n,
 361     foreach_ah_decrypt_next
 362 #undef _
 363   },
 364 };
 365 /* *INDENT-ON* */
 366
 367 /*
 368  * fd.io coding-style-patch-verification: ON
 369  *
 370  * Local Variables:
 371  * eval: (c-set-style "gnu")
 372  * End:
 373  */