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   from = vlib_frame_vector_args (from_frame);
  88   n_left_from = from_frame->n_vectors;
  89   int icv_size;
  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 (ipsec_sa_is_set_USE_ANTI_REPLAY (sa0))
 155             {
 156               int rv = 0;
 157
 158               if (PREDICT_TRUE (ipsec_sa_is_set_USE_EXTENDED_SEQ_NUM (sa0)))
 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                   i_b0->error = node->errors[AH_DECRYPT_ERROR_REPLAY];
 166                   goto trace;
 167                 }
 168             }
 169
 170           vlib_increment_combined_counter
 171             (&ipsec_sa_counters, thread_index, sa_index0,
 172              1, i_b0->current_length);
 173
 174           icv_size = sa0->integ_trunc_size;
 175           if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
 176             {
 177               u8 sig[64];
 178               u8 digest[icv_size];
 179               u8 *icv = ah0->auth_data;
 180               memcpy (digest, icv, icv_size);
 181               clib_memset (icv, 0, icv_size);
 182
 183               if (is_ip6)
 184                 {
 185                   ip_version_traffic_class_and_flow_label =
 186                     ih6->ip_version_traffic_class_and_flow_label;
 187                   hop_limit = ih6->hop_limit;
 188                   ih6->ip_version_traffic_class_and_flow_label = 0x60;
 189                   ih6->hop_limit = 0;
 190                   nexthdr = ah0->nexthdr;
 191                   icv_padding_len =
 192                     ah_calc_icv_padding_len (icv_size, 1 /* is_ipv6 */ );
 193                 }
 194               else
 195                 {
 196                   tos = ih4->tos;
 197                   ttl = ih4->ttl;
 198                   ih4->tos = 0;
 199                   ih4->ttl = 0;
 200                   ih4->checksum = 0;
 201                   ih4->flags_and_fragment_offset = 0;
 202                   icv_padding_len =
 203                     ah_calc_icv_padding_len (icv_size, 0 /* is_ipv6 */ );
 204                 }
 205               hmac_calc (vm, sa0, (u8 *) ih4, i_b0->current_length, sig);
 206
 207               if (PREDICT_FALSE (memcmp (digest, sig, icv_size)))
 208                 {
 209                   i_b0->error = node->errors[AH_DECRYPT_ERROR_INTEG_ERROR];
 210                   goto trace;
 211                 }
 212
 213               if (PREDICT_TRUE (ipsec_sa_is_set_USE_ANTI_REPLAY (sa0)))
 214                 {
 215                   if (PREDICT_TRUE
 216                       (ipsec_sa_is_set_USE_EXTENDED_SEQ_NUM (sa0)))
 217                     esp_replay_advance_esn (sa0, seq);
 218                   else
 219                     esp_replay_advance (sa0, seq);
 220                 }
 221
 222             }
 223
 224           vlib_buffer_advance (i_b0,
 225                                ip_hdr_size + sizeof (ah_header_t) + icv_size +
 226                                icv_padding_len);
 227           i_b0->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
 228
 229           if (PREDICT_TRUE (ipsec_sa_is_set_IS_TUNNEL (sa0)))
 230             {                   /* tunnel mode */
 231               if (PREDICT_TRUE (ah0->nexthdr == IP_PROTOCOL_IP_IN_IP))
 232                 next0 = AH_DECRYPT_NEXT_IP4_INPUT;
 233               else if (ah0->nexthdr == IP_PROTOCOL_IPV6)
 234                 next0 = AH_DECRYPT_NEXT_IP6_INPUT;
 235               else
 236                 {
 237                   i_b0->error =
 238                     node->errors[AH_DECRYPT_ERROR_DECRYPTION_FAILED];
 239                   goto trace;
 240                 }
 241             }
 242           else
 243             {                   /* transport mode */
 244               if (is_ip6)
 245                 {
 246                   vlib_buffer_advance (i_b0, -sizeof (ip6_header_t));
 247                   oh6 = vlib_buffer_get_current (i_b0);
 248                   memmove (oh6, ih6, sizeof (ip6_header_t));
 249
 250                   next0 = AH_DECRYPT_NEXT_IP6_INPUT;
 251                   oh6->protocol = nexthdr;
 252                   oh6->hop_limit = hop_limit;
 253                   oh6->ip_version_traffic_class_and_flow_label =
 254                     ip_version_traffic_class_and_flow_label;
 255                   oh6->payload_length =
 256                     clib_host_to_net_u16 (vlib_buffer_length_in_chain
 257                                           (vm, i_b0) - sizeof (ip6_header_t));
 258                 }
 259               else
 260                 {
 261                   vlib_buffer_advance (i_b0, -sizeof (ip4_header_t));
 262                   oh4 = vlib_buffer_get_current (i_b0);
 263                   memmove (oh4, ih4, sizeof (ip4_header_t));
 264
 265                   next0 = AH_DECRYPT_NEXT_IP4_INPUT;
 266                   oh4->ip_version_and_header_length = 0x45;
 267                   oh4->fragment_id = 0;
 268                   oh4->flags_and_fragment_offset = 0;
 269                   oh4->protocol = ah0->nexthdr;
 270                   oh4->length =
 271                     clib_host_to_net_u16 (vlib_buffer_length_in_chain
 272                                           (vm, i_b0));
 273                   oh4->ttl = ttl;
 274                   oh4->tos = tos;
 275                   oh4->checksum = ip4_header_checksum (oh4);
 276                 }
 277             }
 278
 279           /* for IPSec-GRE tunnel next node is ipsec-gre-input */
 280           if (PREDICT_FALSE
 281               ((vnet_buffer (i_b0)->ipsec.flags) &
 282                IPSEC_FLAG_IPSEC_GRE_TUNNEL))
 283             next0 = AH_DECRYPT_NEXT_IPSEC_GRE_INPUT;
 284
 285
 286           vnet_buffer (i_b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
 287         trace:
 288           if (PREDICT_FALSE (i_b0->flags & VLIB_BUFFER_IS_TRACED))
 289             {
 290               i_b0->flags |= VLIB_BUFFER_IS_TRACED;
 291               ah_decrypt_trace_t *tr =
 292                 vlib_add_trace (vm, node, i_b0, sizeof (*tr));
 293               tr->integ_alg = sa0->integ_alg;
 294               tr->seq_num = seq;
 295             }
 296           vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
 297                                            n_left_to_next, i_bi0, next0);
 298         }
 299       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
 300     }
 301   vlib_node_increment_counter (vm, node->node_index, AH_DECRYPT_ERROR_RX_PKTS,
 302                                from_frame->n_vectors);
 303
 304   return from_frame->n_vectors;
 305 }
 306
 307 VLIB_NODE_FN (ah4_decrypt_node) (vlib_main_t * vm,
 308                                  vlib_node_runtime_t * node,
 309                                  vlib_frame_t * from_frame)
 310 {
 311   return ah_decrypt_inline (vm, node, from_frame, 0 /* is_ip6 */ );
 312 }
 313
 314 /* *INDENT-OFF* */
 315 VLIB_REGISTER_NODE (ah4_decrypt_node) = {
 316   .name = "ah4-decrypt",
 317   .vector_size = sizeof (u32),
 318   .format_trace = format_ah_decrypt_trace,
 319   .type = VLIB_NODE_TYPE_INTERNAL,
 320
 321   .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
 322   .error_strings = ah_decrypt_error_strings,
 323
 324   .n_next_nodes = AH_DECRYPT_N_NEXT,
 325   .next_nodes = {
 326 #define _(s,n) [AH_DECRYPT_NEXT_##s] = n,
 327     foreach_ah_decrypt_next
 328 #undef _
 329   },
 330 };
 331 /* *INDENT-ON* */
 332
 333 VLIB_NODE_FN (ah6_decrypt_node) (vlib_main_t * vm,
 334                                  vlib_node_runtime_t * node,
 335                                  vlib_frame_t * from_frame)
 336 {
 337   return ah_decrypt_inline (vm, node, from_frame, 1 /* is_ip6 */ );
 338 }
 339
 340 /* *INDENT-OFF* */
 341 VLIB_REGISTER_NODE (ah6_decrypt_node) = {
 342   .name = "ah6-decrypt",
 343   .vector_size = sizeof (u32),
 344   .format_trace = format_ah_decrypt_trace,
 345   .type = VLIB_NODE_TYPE_INTERNAL,
 346
 347   .n_errors = ARRAY_LEN(ah_decrypt_error_strings),
 348   .error_strings = ah_decrypt_error_strings,
 349
 350   .n_next_nodes = AH_DECRYPT_N_NEXT,
 351   .next_nodes = {
 352 #define _(s,n) [AH_DECRYPT_NEXT_##s] = n,
 353     foreach_ah_decrypt_next
 354 #undef _
 355   },
 356 };
 357 /* *INDENT-ON* */
 358
 359 /*
 360  * fd.io coding-style-patch-verification: ON
 361  *
 362  * Local Variables:
 363  * eval: (c-set-style "gnu")
 364  * End:
 365  */