src/vnet/ipsec/esp_decrypt.c

   1 /*
   2  * esp_decrypt.c : IPSec ESP 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
  25 #define foreach_esp_decrypt_next                \
  26 _(DROP, "error-drop")                           \
  27 _(IP4_INPUT, "ip4-input")                       \
  28 _(IP6_INPUT, "ip6-input")                       \
  29 _(IPSEC_GRE_INPUT, "ipsec-gre-input")
  30
  31 #define _(v, s) ESP_DECRYPT_NEXT_##v,
  32 typedef enum
  33 {
  34   foreach_esp_decrypt_next
  35 #undef _
  36     ESP_DECRYPT_N_NEXT,
  37 } esp_decrypt_next_t;
  38
  39
  40 #define foreach_esp_decrypt_error                   \
  41  _(RX_PKTS, "ESP pkts received")                    \
  42  _(NO_BUFFER, "No buffer (packed dropped)")         \
  43  _(DECRYPTION_FAILED, "ESP 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) ESP_DECRYPT_ERROR_##sym,
  52   foreach_esp_decrypt_error
  53 #undef _
  54     ESP_DECRYPT_N_ERROR,
  55 } esp_decrypt_error_t;
  56
  57 static char *esp_decrypt_error_strings[] = {
  58 #define _(sym,string) string,
  59   foreach_esp_decrypt_error
  60 #undef _
  61 };
  62
  63 typedef struct
  64 {
  65   ipsec_crypto_alg_t crypto_alg;
  66   ipsec_integ_alg_t integ_alg;
  67 } esp_decrypt_trace_t;
  68
  69 /* packet trace format function */
  70 static u8 *
  71 format_esp_decrypt_trace (u8 * s, va_list * args)
  72 {
  73   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  74   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  75   esp_decrypt_trace_t *t = va_arg (*args, esp_decrypt_trace_t *);
  76
  77   s = format (s, "esp: crypto %U integrity %U",
  78               format_ipsec_crypto_alg, t->crypto_alg,
  79               format_ipsec_integ_alg, t->integ_alg);
  80   return s;
  81 }
  82
  83 always_inline void
  84 esp_decrypt_aes_cbc (ipsec_crypto_alg_t alg,
  85                      u8 * in, u8 * out, size_t in_len, u8 * key, u8 * iv)
  86 {
  87   esp_main_t *em = &esp_main;
  88   u32 cpu_index = os_get_cpu_number ();
  89   EVP_CIPHER_CTX *ctx = &(em->per_thread_data[cpu_index].decrypt_ctx);
  90   const EVP_CIPHER *cipher = NULL;
  91   int out_len;
  92
  93   ASSERT (alg < IPSEC_CRYPTO_N_ALG);
  94
  95   if (PREDICT_FALSE (em->esp_crypto_algs[alg].type == 0))
  96     return;
  97
  98   if (PREDICT_FALSE (alg != em->per_thread_data[cpu_index].last_decrypt_alg))
  99     {
 100       cipher = em->esp_crypto_algs[alg].type;
 101       em->per_thread_data[cpu_index].last_decrypt_alg = alg;
 102     }
 103
 104   EVP_DecryptInit_ex (ctx, cipher, NULL, key, iv);
 105
 106   EVP_DecryptUpdate (ctx, out, &out_len, in, in_len);
 107   EVP_DecryptFinal_ex (ctx, out + out_len, &out_len);
 108 }
 109
 110 static uword
 111 esp_decrypt_node_fn (vlib_main_t * vm,
 112                      vlib_node_runtime_t * node, vlib_frame_t * from_frame)
 113 {
 114   u32 n_left_from, *from, next_index, *to_next;
 115   ipsec_main_t *im = &ipsec_main;
 116   esp_main_t *em = &esp_main;
 117   u32 *recycle = 0;
 118   from = vlib_frame_vector_args (from_frame);
 119   n_left_from = from_frame->n_vectors;
 120   u32 cpu_index = os_get_cpu_number ();
 121
 122   ipsec_alloc_empty_buffers (vm, im);
 123
 124   u32 *empty_buffers = im->empty_buffers[cpu_index];
 125
 126   if (PREDICT_FALSE (vec_len (empty_buffers) < n_left_from))
 127     {
 128       vlib_node_increment_counter (vm, esp_decrypt_node.index,
 129                                    ESP_DECRYPT_ERROR_NO_BUFFER, n_left_from);
 130       goto free_buffers_and_exit;
 131     }
 132
 133   next_index = node->cached_next_index;
 134
 135   while (n_left_from > 0)
 136     {
 137       u32 n_left_to_next;
 138
 139       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
 140
 141       while (n_left_from > 0 && n_left_to_next > 0)
 142         {
 143           u32 i_bi0, o_bi0 = (u32) ~ 0, next0;
 144           vlib_buffer_t *i_b0;
 145           vlib_buffer_t *o_b0 = 0;
 146           esp_header_t *esp0;
 147           ipsec_sa_t *sa0;
 148           u32 sa_index0 = ~0;
 149           u32 seq;
 150           ip4_header_t *ih4 = 0, *oh4 = 0;
 151           ip6_header_t *ih6 = 0, *oh6 = 0;
 152           u8 tunnel_mode = 1;
 153           u8 transport_ip6 = 0;
 154
 155
 156           i_bi0 = from[0];
 157           from += 1;
 158           n_left_from -= 1;
 159           n_left_to_next -= 1;
 160
 161           next0 = ESP_DECRYPT_NEXT_DROP;
 162
 163           i_b0 = vlib_get_buffer (vm, i_bi0);
 164           esp0 = vlib_buffer_get_current (i_b0);
 165
 166           sa_index0 = vnet_buffer (i_b0)->ipsec.sad_index;
 167           sa0 = pool_elt_at_index (im->sad, sa_index0);
 168
 169           seq = clib_host_to_net_u32 (esp0->seq);
 170
 171           /* anti-replay check */
 172           if (sa0->use_anti_replay)
 173             {
 174               int rv = 0;
 175
 176               if (PREDICT_TRUE (sa0->use_esn))
 177                 rv = esp_replay_check_esn (sa0, seq);
 178               else
 179                 rv = esp_replay_check (sa0, seq);
 180
 181               if (PREDICT_FALSE (rv))
 182                 {
 183                   clib_warning ("anti-replay SPI %u seq %u", sa0->spi, seq);
 184                   vlib_node_increment_counter (vm, esp_decrypt_node.index,
 185                                                ESP_DECRYPT_ERROR_REPLAY, 1);
 186                   o_bi0 = i_bi0;
 187                   to_next[0] = o_bi0;
 188                   to_next += 1;
 189                   goto trace;
 190                 }
 191             }
 192
 193           if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
 194             {
 195               u8 sig[64];
 196               int icv_size = em->esp_integ_algs[sa0->integ_alg].trunc_size;
 197               memset (sig, 0, sizeof (sig));
 198               u8 *icv =
 199                 vlib_buffer_get_current (i_b0) + i_b0->current_length -
 200                 icv_size;
 201               i_b0->current_length -= icv_size;
 202
 203               hmac_calc (sa0->integ_alg, sa0->integ_key, sa0->integ_key_len,
 204                          (u8 *) esp0, i_b0->current_length, sig, sa0->use_esn,
 205                          sa0->seq_hi);
 206
 207               if (PREDICT_FALSE (memcmp (icv, sig, icv_size)))
 208                 {
 209                   vlib_node_increment_counter (vm, esp_decrypt_node.index,
 210                                                ESP_DECRYPT_ERROR_INTEG_ERROR,
 211                                                1);
 212                   o_bi0 = i_bi0;
 213                   to_next[0] = o_bi0;
 214                   to_next += 1;
 215                   goto trace;
 216                 }
 217             }
 218
 219           if (PREDICT_TRUE (sa0->use_anti_replay))
 220             {
 221               if (PREDICT_TRUE (sa0->use_esn))
 222                 esp_replay_advance_esn (sa0, seq);
 223               else
 224                 esp_replay_advance (sa0, seq);
 225             }
 226
 227           /* grab free buffer */
 228           uword last_empty_buffer = vec_len (empty_buffers) - 1;
 229           o_bi0 = empty_buffers[last_empty_buffer];
 230           to_next[0] = o_bi0;
 231           to_next += 1;
 232           o_b0 = vlib_get_buffer (vm, o_bi0);
 233           vlib_prefetch_buffer_with_index (vm,
 234                                            empty_buffers[last_empty_buffer -
 235                                                          1], STORE);
 236           _vec_len (empty_buffers) = last_empty_buffer;
 237
 238           /* add old buffer to the recycle list */
 239           vec_add1 (recycle, i_bi0);
 240
 241           if (sa0->crypto_alg >= IPSEC_CRYPTO_ALG_AES_CBC_128 &&
 242               sa0->crypto_alg <= IPSEC_CRYPTO_ALG_AES_CBC_256)
 243             {
 244               const int BLOCK_SIZE = 16;
 245               const int IV_SIZE = 16;
 246               esp_footer_t *f0;
 247               u8 ip_hdr_size = 0;
 248
 249               int blocks =
 250                 (i_b0->current_length - sizeof (esp_header_t) -
 251                  IV_SIZE) / BLOCK_SIZE;
 252
 253               o_b0->current_data = sizeof (ethernet_header_t);
 254
 255               /* transport mode */
 256               if (PREDICT_FALSE (!sa0->is_tunnel && !sa0->is_tunnel_ip6))
 257                 {
 258                   tunnel_mode = 0;
 259                   ih4 =
 260                     (ip4_header_t *) (i_b0->data +
 261                                       sizeof (ethernet_header_t));
 262                   if (PREDICT_TRUE
 263                       ((ih4->ip_version_and_header_length & 0xF0) != 0x40))
 264                     {
 265                       if (PREDICT_TRUE
 266                           ((ih4->ip_version_and_header_length & 0xF0) ==
 267                            0x60))
 268                         {
 269                           transport_ip6 = 1;
 270                           ip_hdr_size = sizeof (ip6_header_t);
 271                           ih6 =
 272                             (ip6_header_t *) (i_b0->data +
 273                                               sizeof (ethernet_header_t));
 274                           oh6 = vlib_buffer_get_current (o_b0);
 275                         }
 276                       else
 277                         {
 278                           vlib_node_increment_counter (vm,
 279                                                        esp_decrypt_node.index,
 280                                                        ESP_DECRYPT_ERROR_NOT_IP,
 281                                                        1);
 282                           o_b0 = 0;
 283                           goto trace;
 284                         }
 285                     }
 286                   else
 287                     {
 288                       oh4 = vlib_buffer_get_current (o_b0);
 289                       ip_hdr_size = sizeof (ip4_header_t);
 290                     }
 291                 }
 292
 293               esp_decrypt_aes_cbc (sa0->crypto_alg,
 294                                    esp0->data + IV_SIZE,
 295                                    (u8 *) vlib_buffer_get_current (o_b0) +
 296                                    ip_hdr_size, BLOCK_SIZE * blocks,
 297                                    sa0->crypto_key, esp0->data);
 298
 299               o_b0->current_length = (blocks * 16) - 2 + ip_hdr_size;
 300               o_b0->flags = VLIB_BUFFER_TOTAL_LENGTH_VALID;
 301               f0 =
 302                 (esp_footer_t *) ((u8 *) vlib_buffer_get_current (o_b0) +
 303                                   o_b0->current_length);
 304               o_b0->current_length -= f0->pad_length;
 305
 306               /* tunnel mode */
 307               if (PREDICT_TRUE (tunnel_mode))
 308                 {
 309                   if (PREDICT_TRUE (f0->next_header == IP_PROTOCOL_IP_IN_IP))
 310                     {
 311                       next0 = ESP_DECRYPT_NEXT_IP4_INPUT;
 312                       oh4 = vlib_buffer_get_current (o_b0);
 313                     }
 314                   else if (f0->next_header == IP_PROTOCOL_IPV6)
 315                     next0 = ESP_DECRYPT_NEXT_IP6_INPUT;
 316                   else
 317                     {
 318                       clib_warning ("next header: 0x%x", f0->next_header);
 319                       vlib_node_increment_counter (vm, esp_decrypt_node.index,
 320                                                    ESP_DECRYPT_ERROR_DECRYPTION_FAILED,
 321                                                    1);
 322                       o_b0 = 0;
 323                       goto trace;
 324                     }
 325                 }
 326               /* transport mode */
 327               else
 328                 {
 329                   if (PREDICT_FALSE (transport_ip6))
 330                     {
 331                       next0 = ESP_DECRYPT_NEXT_IP6_INPUT;
 332                       oh6->ip_version_traffic_class_and_flow_label =
 333                         ih6->ip_version_traffic_class_and_flow_label;
 334                       oh6->protocol = f0->next_header;
 335                       oh6->hop_limit = ih6->hop_limit;
 336                       oh6->src_address.as_u64[0] = ih6->src_address.as_u64[0];
 337                       oh6->src_address.as_u64[1] = ih6->src_address.as_u64[1];
 338                       oh6->dst_address.as_u64[0] = ih6->dst_address.as_u64[0];
 339                       oh6->dst_address.as_u64[1] = ih6->dst_address.as_u64[1];
 340                       oh6->payload_length =
 341                         clib_host_to_net_u16 (vlib_buffer_length_in_chain
 342                                               (vm,
 343                                                o_b0) - sizeof (ip6_header_t));
 344                     }
 345                   else
 346                     {
 347                       next0 = ESP_DECRYPT_NEXT_IP4_INPUT;
 348                       oh4->ip_version_and_header_length = 0x45;
 349                       oh4->tos = ih4->tos;
 350                       oh4->fragment_id = 0;
 351                       oh4->flags_and_fragment_offset = 0;
 352                       oh4->ttl = ih4->ttl;
 353                       oh4->protocol = f0->next_header;
 354                       oh4->src_address.as_u32 = ih4->src_address.as_u32;
 355                       oh4->dst_address.as_u32 = ih4->dst_address.as_u32;
 356                       oh4->length =
 357                         clib_host_to_net_u16 (vlib_buffer_length_in_chain
 358                                               (vm, o_b0));
 359                       oh4->checksum = ip4_header_checksum (oh4);
 360                     }
 361                 }
 362
 363               /* for IPSec-GRE tunnel next node is ipsec-gre-input */
 364               if (PREDICT_FALSE
 365                   ((vnet_buffer (i_b0)->ipsec.flags) &
 366                    IPSEC_FLAG_IPSEC_GRE_TUNNEL))
 367                 next0 = ESP_DECRYPT_NEXT_IPSEC_GRE_INPUT;
 368
 369               vnet_buffer (o_b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
 370             }
 371
 372         trace:
 373           if (PREDICT_FALSE (i_b0->flags & VLIB_BUFFER_IS_TRACED))
 374             {
 375               if (o_b0)
 376                 {
 377                   o_b0->flags |= VLIB_BUFFER_IS_TRACED;
 378                   o_b0->trace_index = i_b0->trace_index;
 379                   esp_decrypt_trace_t *tr =
 380                     vlib_add_trace (vm, node, o_b0, sizeof (*tr));
 381                   tr->crypto_alg = sa0->crypto_alg;
 382                   tr->integ_alg = sa0->integ_alg;
 383                 }
 384             }
 385
 386           vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
 387                                            n_left_to_next, o_bi0, next0);
 388         }
 389       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
 390     }
 391   vlib_node_increment_counter (vm, esp_decrypt_node.index,
 392                                ESP_DECRYPT_ERROR_RX_PKTS,
 393                                from_frame->n_vectors);
 394
 395 free_buffers_and_exit:
 396   if (recycle)
 397     vlib_buffer_free (vm, recycle, vec_len (recycle));
 398   vec_free (recycle);
 399   return from_frame->n_vectors;
 400 }
 401
 402
 403 /* *INDENT-OFF* */
 404 VLIB_REGISTER_NODE (esp_decrypt_node) = {
 405   .function = esp_decrypt_node_fn,
 406   .name = "esp-decrypt",
 407   .vector_size = sizeof (u32),
 408   .format_trace = format_esp_decrypt_trace,
 409   .type = VLIB_NODE_TYPE_INTERNAL,
 410
 411   .n_errors = ARRAY_LEN(esp_decrypt_error_strings),
 412   .error_strings = esp_decrypt_error_strings,
 413
 414   .n_next_nodes = ESP_DECRYPT_N_NEXT,
 415   .next_nodes = {
 416 #define _(s,n) [ESP_DECRYPT_NEXT_##s] = n,
 417     foreach_esp_decrypt_next
 418 #undef _
 419   },
 420 };
 421 /* *INDENT-ON* */
 422
 423 VLIB_NODE_FUNCTION_MULTIARCH (esp_decrypt_node, esp_decrypt_node_fn)
 424 /*
 425  * fd.io coding-style-patch-verification: ON
 426  *
 427  * Local Variables:
 428  * eval: (c-set-style "gnu")
 429  * End:
 430  */