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
  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  _(NOT_IP, "Not IP packet (dropped)")
  47
  48
  49 typedef enum
  50 {
  51 #define _(sym,str) AH_DECRYPT_ERROR_##sym,
  52   foreach_ah_decrypt_error
  53 #undef _
  54     AH_DECRYPT_N_ERROR,
  55 } ah_decrypt_error_t;
  56
  57 static char *ah_decrypt_error_strings[] = {
  58 #define _(sym,string) string,
  59   foreach_ah_decrypt_error
  60 #undef _
  61 };
  62
  63 typedef struct
  64 {
  65   ipsec_integ_alg_t integ_alg;
  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", format_ipsec_integ_alg, t->integ_alg);
  77   return s;
  78 }
  79
  80 static uword
  81 ah_decrypt_node_fn (vlib_main_t * vm,
  82                     vlib_node_runtime_t * node, vlib_frame_t * from_frame)
  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 tunnel_mode = 1;
 111           u8 transport_ip6 = 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           if ((ih4->ip_version_and_header_length & 0xF0) == 0x40)
 137             {
 138               ip_hdr_size = ip4_header_bytes (ih4);
 139               ah0 = (ah_header_t *) ((u8 *) ih4 + ip_hdr_size);
 140             }
 141           else if ((ih4->ip_version_and_header_length & 0xF0) == 0x60)
 142             {
 143               ip6_ext_header_t *prev = NULL;
 144               ip6_ext_header_find_t (ih6, prev, ah0, IP_PROTOCOL_IPSEC_AH);
 145               ip_hdr_size = sizeof (ip6_header_t);
 146               ASSERT ((u8 *) ah0 - (u8 *) ih6 == ip_hdr_size);
 147             }
 148           else
 149             {
 150               vlib_node_increment_counter (vm, ah_decrypt_node.index,
 151                                            AH_DECRYPT_ERROR_NOT_IP, 1);
 152               goto trace;
 153             }
 154
 155           seq = clib_host_to_net_u32 (ah0->seq_no);
 156           /* anti-replay check */
 157           //TODO UT remaining
 158           if (sa0->use_anti_replay)
 159             {
 160               int rv = 0;
 161
 162               if (PREDICT_TRUE (sa0->use_esn))
 163                 rv = esp_replay_check_esn (sa0, seq);
 164               else
 165                 rv = esp_replay_check (sa0, seq);
 166
 167               if (PREDICT_FALSE (rv))
 168                 {
 169                   clib_warning ("anti-replay SPI %u seq %u", sa0->spi, seq);
 170                   vlib_node_increment_counter (vm, ah_decrypt_node.index,
 171                                                AH_DECRYPT_ERROR_REPLAY, 1);
 172                   to_next[0] = i_bi0;
 173                   to_next += 1;
 174                   goto trace;
 175                 }
 176             }
 177
 178
 179           sa0->total_data_size += i_b0->current_length;
 180           icv_size =
 181             em->ipsec_proto_main_integ_algs[sa0->integ_alg].trunc_size;
 182           if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
 183             {
 184               u8 sig[64];
 185               u8 digest[64];
 186               memset (sig, 0, sizeof (sig));
 187               memset (digest, 0, sizeof (digest));
 188               u8 *icv = ah0->auth_data;
 189               memcpy (digest, icv, icv_size);
 190               memset (icv, 0, icv_size);
 191
 192               if ((ih4->ip_version_and_header_length & 0xF0) == 0x40)
 193                 {
 194                   tos = ih4->tos;
 195                   ttl = ih4->ttl;
 196                   ih4->tos = 0;
 197                   ih4->ttl = 0;
 198                   ih4->checksum = 0;
 199                   ih4->flags_and_fragment_offset = 0;
 200                   icv_padding_len =
 201                     ah_calc_icv_padding_len (icv_size, 0 /* is_ipv6 */ );
 202                 }
 203               else
 204                 {
 205                   ip_version_traffic_class_and_flow_label =
 206                     ih6->ip_version_traffic_class_and_flow_label;
 207                   hop_limit = ih6->hop_limit;
 208                   ih6->ip_version_traffic_class_and_flow_label = 0x60;
 209                   ih6->hop_limit = 0;
 210                   nexthdr = ah0->nexthdr;
 211                   icv_padding_len =
 212                     ah_calc_icv_padding_len (icv_size, 1 /* is_ipv6 */ );
 213                 }
 214               hmac_calc (sa0->integ_alg, sa0->integ_key, sa0->integ_key_len,
 215                          (u8 *) ih4, i_b0->current_length, sig, sa0->use_esn,
 216                          sa0->seq_hi);
 217
 218               if (PREDICT_FALSE (memcmp (digest, sig, icv_size)))
 219                 {
 220                   vlib_node_increment_counter (vm, ah_decrypt_node.index,
 221                                                AH_DECRYPT_ERROR_INTEG_ERROR,
 222                                                1);
 223                   to_next[0] = i_bi0;
 224                   to_next += 1;
 225                   goto trace;
 226                 }
 227
 228               //TODO UT remaining
 229               if (PREDICT_TRUE (sa0->use_anti_replay))
 230                 {
 231                   if (PREDICT_TRUE (sa0->use_esn))
 232                     esp_replay_advance_esn (sa0, seq);
 233                   else
 234                     esp_replay_advance (sa0, seq);
 235                 }
 236
 237             }
 238
 239           vlib_buffer_advance (i_b0,
 240                                ip_hdr_size + sizeof (ah_header_t) + icv_size +
 241                                icv_padding_len);
 242           i_b0->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
 243
 244           /* transport mode */
 245           if (PREDICT_FALSE (!sa0->is_tunnel && !sa0->is_tunnel_ip6))
 246             {
 247               tunnel_mode = 0;
 248
 249               if (PREDICT_TRUE
 250                   ((ih4->ip_version_and_header_length & 0xF0) != 0x40))
 251                 {
 252                   if (PREDICT_TRUE
 253                       ((ih4->ip_version_and_header_length & 0xF0) == 0x60))
 254                     transport_ip6 = 1;
 255                   else
 256                     {
 257                       clib_warning ("next header: 0x%x", ah0->nexthdr);
 258                       vlib_node_increment_counter (vm, ah_decrypt_node.index,
 259                                                    AH_DECRYPT_ERROR_NOT_IP,
 260                                                    1);
 261                       goto trace;
 262                     }
 263                 }
 264             }
 265
 266           if (PREDICT_TRUE (tunnel_mode))
 267             {
 268               if (PREDICT_TRUE (ah0->nexthdr == IP_PROTOCOL_IP_IN_IP))
 269                 next0 = AH_DECRYPT_NEXT_IP4_INPUT;
 270               else if (ah0->nexthdr == IP_PROTOCOL_IPV6)
 271                 next0 = AH_DECRYPT_NEXT_IP6_INPUT;
 272               else
 273                 {
 274                   clib_warning ("next header: 0x%x", ah0->nexthdr);
 275                   vlib_node_increment_counter (vm, ah_decrypt_node.index,
 276                                                AH_DECRYPT_ERROR_DECRYPTION_FAILED,
 277                                                1);
 278                   goto trace;
 279                 }
 280             }
 281           /* transport mode */
 282           else
 283             {
 284               if (PREDICT_FALSE (transport_ip6))
 285                 {
 286                   vlib_buffer_advance (i_b0, -sizeof (ip6_header_t));
 287                   oh6 = vlib_buffer_get_current (i_b0);
 288                   memmove (oh6, ih6, sizeof (ip6_header_t));
 289
 290                   next0 = AH_DECRYPT_NEXT_IP6_INPUT;
 291                   oh6->protocol = nexthdr;
 292                   oh6->hop_limit = hop_limit;
 293                   oh6->ip_version_traffic_class_and_flow_label =
 294                     ip_version_traffic_class_and_flow_label;
 295                   oh6->payload_length =
 296                     clib_host_to_net_u16 (vlib_buffer_length_in_chain
 297                                           (vm, i_b0) - sizeof (ip6_header_t));
 298                 }
 299               else
 300                 {
 301                   vlib_buffer_advance (i_b0, -sizeof (ip4_header_t));
 302                   oh4 = vlib_buffer_get_current (i_b0);
 303                   memmove (oh4, ih4, sizeof (ip4_header_t));
 304
 305                   next0 = AH_DECRYPT_NEXT_IP4_INPUT;
 306                   oh4->ip_version_and_header_length = 0x45;
 307                   oh4->fragment_id = 0;
 308                   oh4->flags_and_fragment_offset = 0;
 309                   oh4->protocol = ah0->nexthdr;
 310                   oh4->length =
 311                     clib_host_to_net_u16 (vlib_buffer_length_in_chain
 312                                           (vm, i_b0));
 313                   oh4->ttl = ttl;
 314                   oh4->tos = tos;
 315                   oh4->checksum = ip4_header_checksum (oh4);
 316                 }
 317             }
 318
 319           /* for IPSec-GRE tunnel next node is ipsec-gre-input */
 320           if (PREDICT_FALSE
 321               ((vnet_buffer (i_b0)->ipsec.flags) &
 322                IPSEC_FLAG_IPSEC_GRE_TUNNEL))
 323             next0 = AH_DECRYPT_NEXT_IPSEC_GRE_INPUT;
 324
 325
 326           vnet_buffer (i_b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
 327         trace:
 328           if (PREDICT_FALSE (i_b0->flags & VLIB_BUFFER_IS_TRACED))
 329             {
 330               i_b0->flags |= VLIB_BUFFER_IS_TRACED;
 331               ah_decrypt_trace_t *tr =
 332                 vlib_add_trace (vm, node, i_b0, sizeof (*tr));
 333               tr->integ_alg = sa0->integ_alg;
 334             }
 335           vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
 336                                            n_left_to_next, i_bi0, next0);
 337         }
 338       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
 339     }
 340   vlib_node_increment_counter (vm, ah_decrypt_node.index,
 341                                AH_DECRYPT_ERROR_RX_PKTS,
 342                                from_frame->n_vectors);
 343
 344   return from_frame->n_vectors;
 345 }
 346
 347
 348 /* *INDENT-OFF* */
 349 VLIB_REGISTER_NODE (ah_decrypt_node) = {
 350   .function = ah_decrypt_node_fn,
 351   .name = "ah-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 VLIB_NODE_FUNCTION_MULTIARCH (ah_decrypt_node, ah_decrypt_node_fn)
 369 /*
 370  * fd.io coding-style-patch-verification: ON
 371  *
 372  * Local Variables:
 373  * eval: (c-set-style "gnu")
 374  * End:
 375  */