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;
  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
  93   while (n_left_from > 0)
  94     {
  95       u32 n_left_to_next;
  96
  97       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
  98
  99       while (n_left_from > 0 && n_left_to_next > 0)
 100         {
 101           u32 i_bi0;
 102           u32 next0;
 103           vlib_buffer_t *i_b0;
 104           ah_header_t *ah0;
 105           ipsec_sa_t *sa0;
 106           u32 sa_index0 = ~0;
 107           u32 seq;
 108           ip4_header_t *ih4 = 0, *oh4 = 0;
 109           ip6_header_t *ih6 = 0, *oh6 = 0;
 110           u8 ip_hdr_size = 0;
 111           u8 tos = 0;
 112           u8 ttl = 0;
 113           u32 ip_version_traffic_class_and_flow_label = 0;
 114           u8 hop_limit = 0;
 115           u8 nexthdr = 0;
 116           u8 icv_padding_len = 0;
 117
 118
 119           i_bi0 = from[0];
 120           from += 1;
 121           n_left_from -= 1;
 122           n_left_to_next -= 1;
 123
 124           next0 = AH_DECRYPT_NEXT_DROP;
 125
 126           i_b0 = vlib_get_buffer (vm, i_bi0);
 127           to_next[0] = i_bi0;
 128           to_next += 1;
 129           ih4 = vlib_buffer_get_current (i_b0);
 130           ih6 = vlib_buffer_get_current (i_b0);
 131           sa_index0 = vnet_buffer (i_b0)->ipsec.sad_index;
 132           sa0 = pool_elt_at_index (im->sad, sa_index0);
 133
 134           if (is_ip6)
 135             {
 136               ip6_ext_header_t *prev = NULL;
 137               ip6_ext_header_find_t (ih6, prev, ah0, IP_PROTOCOL_IPSEC_AH);
 138               ip_hdr_size = sizeof (ip6_header_t);
 139               ASSERT ((u8 *) ah0 - (u8 *) ih6 == ip_hdr_size);
 140             }
 141           else
 142             {
 143               ip_hdr_size = ip4_header_bytes (ih4);
 144               ah0 = (ah_header_t *) ((u8 *) ih4 + ip_hdr_size);
 145             }
 146
 147           seq = clib_host_to_net_u32 (ah0->seq_no);
 148
 149           /* anti-replay check */
 150           if (sa0->use_anti_replay)
 151             {
 152               int rv = 0;
 153
 154               if (PREDICT_TRUE (sa0->use_esn))
 155                 rv = esp_replay_check_esn (sa0, seq);
 156               else
 157                 rv = esp_replay_check (sa0, seq);
 158
 159               if (PREDICT_FALSE (rv))
 160                 {
 161                   if (is_ip6)
 162                     vlib_node_increment_counter (vm,
 163                                                  ah6_decrypt_node.index,
 164                                                  AH_DECRYPT_ERROR_REPLAY, 1);
 165                   else
 166                     vlib_node_increment_counter (vm,
 167                                                  ah4_decrypt_node.index,
 168                                                  AH_DECRYPT_ERROR_REPLAY, 1);
 169                   goto trace;
 170                 }
 171             }
 172
 173
 174           sa0->total_data_size += i_b0->current_length;
 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, sa0->integ_key_len,
 210                          (u8 *) ih4, i_b0->current_length, sig, sa0->use_esn,
 211                          sa0->seq_hi);
 212
 213               if (PREDICT_FALSE (memcmp (digest, sig, icv_size)))
 214                 {
 215                   if (is_ip6)
 216                     vlib_node_increment_counter (vm,
 217                                                  ah6_decrypt_node.index,
 218                                                  AH_DECRYPT_ERROR_INTEG_ERROR,
 219                                                  1);
 220                   else
 221                     vlib_node_increment_counter (vm,
 222                                                  ah4_decrypt_node.index,
 223                                                  AH_DECRYPT_ERROR_INTEG_ERROR,
 224                                                  1);
 225                   goto trace;
 226                 }
 227
 228               if (PREDICT_TRUE (sa0->use_anti_replay))
 229                 {
 230                   if (PREDICT_TRUE (sa0->use_esn))
 231                     esp_replay_advance_esn (sa0, seq);
 232                   else
 233                     esp_replay_advance (sa0, seq);
 234                 }
 235
 236             }
 237
 238           vlib_buffer_advance (i_b0,
 239                                ip_hdr_size + sizeof (ah_header_t) + icv_size +
 240                                icv_padding_len);
 241           i_b0->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
 242
 243           if (PREDICT_TRUE (sa0->is_tunnel))
 244             {                   /* tunnel mode */
 245               if (PREDICT_TRUE (ah0->nexthdr == IP_PROTOCOL_IP_IN_IP))
 246                 next0 = AH_DECRYPT_NEXT_IP4_INPUT;
 247               else if (ah0->nexthdr == IP_PROTOCOL_IPV6)
 248                 next0 = AH_DECRYPT_NEXT_IP6_INPUT;
 249               else
 250                 {
 251                   if (is_ip6)
 252                     vlib_node_increment_counter (vm,
 253                                                  ah6_decrypt_node.index,
 254                                                  AH_DECRYPT_ERROR_DECRYPTION_FAILED,
 255                                                  1);
 256                   else
 257                     vlib_node_increment_counter (vm,
 258                                                  ah4_decrypt_node.index,
 259                                                  AH_DECRYPT_ERROR_DECRYPTION_FAILED,
 260                                                  1);
 261                   goto trace;
 262                 }
 263             }
 264           else
 265             {                   /* transport mode */
 266               if (is_ip6)
 267                 {
 268                   vlib_buffer_advance (i_b0, -sizeof (ip6_header_t));
 269                   oh6 = vlib_buffer_get_current (i_b0);
 270                   memmove (oh6, ih6, sizeof (ip6_header_t));
 271
 272                   next0 = AH_DECRYPT_NEXT_IP6_INPUT;
 273                   oh6->protocol = nexthdr;
 274                   oh6->hop_limit = hop_limit;
 275                   oh6->ip_version_traffic_class_and_flow_label =
 276                     ip_version_traffic_class_and_flow_label;
 277                   oh6->payload_length =
 278                     clib_host_to_net_u16 (vlib_buffer_length_in_chain
 279                                           (vm, i_b0) - sizeof (ip6_header_t));
 280                 }
 281               else
 282                 {
 283                   vlib_buffer_advance (i_b0, -sizeof (ip4_header_t));
 284                   oh4 = vlib_buffer_get_current (i_b0);
 285                   memmove (oh4, ih4, sizeof (ip4_header_t));
 286
 287                   next0 = AH_DECRYPT_NEXT_IP4_INPUT;
 288                   oh4->ip_version_and_header_length = 0x45;
 289                   oh4->fragment_id = 0;
 290                   oh4->flags_and_fragment_offset = 0;
 291                   oh4->protocol = ah0->nexthdr;
 292                   oh4->length =
 293                     clib_host_to_net_u16 (vlib_buffer_length_in_chain
 294                                           (vm, i_b0));
 295                   oh4->ttl = ttl;
 296                   oh4->tos = tos;
 297                   oh4->checksum = ip4_header_checksum (oh4);
 298                 }
 299             }
 300
 301           /* for IPSec-GRE tunnel next node is ipsec-gre-input */
 302           if (PREDICT_FALSE
 303               ((vnet_buffer (i_b0)->ipsec.flags) &
 304                IPSEC_FLAG_IPSEC_GRE_TUNNEL))
 305             next0 = AH_DECRYPT_NEXT_IPSEC_GRE_INPUT;
 306
 307
 308           vnet_buffer (i_b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
 309         trace:
 310           if (PREDICT_FALSE (i_b0->flags & VLIB_BUFFER_IS_TRACED))
 311             {
 312               i_b0->flags |= VLIB_BUFFER_IS_TRACED;
 313               ah_decrypt_trace_t *tr =
 314                 vlib_add_trace (vm, node, i_b0, sizeof (*tr));
 315               tr->integ_alg = sa0->integ_alg;
 316               tr->seq_num = seq;
 317             }
 318           vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
 319                                            n_left_to_next, i_bi0, next0);
 320         }
 321       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
 322     }
 323   if (is_ip6)
 324     vlib_node_increment_counter (vm, ah6_decrypt_node.index,
 325                                  AH_DECRYPT_ERROR_RX_PKTS,
 326                                  from_frame->n_vectors);
 327   else
 328     vlib_node_increment_counter (vm, ah4_decrypt_node.index,
 329                                  AH_DECRYPT_ERROR_RX_PKTS,
 330                                  from_frame->n_vectors);
 331
 332   return from_frame->n_vectors;
 333 }
 334
 335 VLIB_NODE_FN (ah4_decrypt_node) (vlib_main_t * vm,
 336                                  vlib_node_runtime_t * node,
 337                                  vlib_frame_t * from_frame)
 338 {
 339   return ah_decrypt_inline (vm, node, from_frame, 0 /* is_ip6 */ );
 340 }
 341
 342 /* *INDENT-OFF* */
 343 VLIB_REGISTER_NODE (ah4_decrypt_node) = {
 344   .name = "ah4-decrypt",
 345   .vector_size = sizeof (u32),
 346   .format_trace = format_ah_decrypt_trace,
 347   .type = VLIB_NODE_TYPE_INTERNAL,
 348
 349   .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
 350   .error_strings = ah_decrypt_error_strings,
 351
 352   .n_next_nodes = AH_DECRYPT_N_NEXT,
 353   .next_nodes = {
 354 #define _(s,n) [AH_DECRYPT_NEXT_##s] = n,
 355     foreach_ah_decrypt_next
 356 #undef _
 357   },
 358 };
 359 /* *INDENT-ON* */
 360
 361 VLIB_NODE_FN (ah6_decrypt_node) (vlib_main_t * vm,
 362                                  vlib_node_runtime_t * node,
 363                                  vlib_frame_t * from_frame)
 364 {
 365   return ah_decrypt_inline (vm, node, from_frame, 1 /* is_ip6 */ );
 366 }
 367
 368 /* *INDENT-OFF* */
 369 VLIB_REGISTER_NODE (ah6_decrypt_node) = {
 370   .name = "ah6-decrypt",
 371   .vector_size = sizeof (u32),
 372   .format_trace = format_ah_decrypt_trace,
 373   .type = VLIB_NODE_TYPE_INTERNAL,
 374
 375   .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
 376   .error_strings = ah_decrypt_error_strings,
 377
 378   .n_next_nodes = AH_DECRYPT_N_NEXT,
 379   .next_nodes = {
 380 #define _(s,n) [AH_DECRYPT_NEXT_##s] = n,
 381     foreach_ah_decrypt_next
 382 #undef _
 383   },
 384 };
 385 /* *INDENT-ON* */
 386
 387 /*
 388  * fd.io coding-style-patch-verification: ON
 389  *
 390  * Local Variables:
 391  * eval: (c-set-style "gnu")
 392  * End:
 393  */