2 * esp_decrypt.c : IPSec ESP decrypt node
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:
9 * http://www.apache.org/licenses/LICENSE-2.0
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.
18 #include <vnet/vnet.h>
19 #include <vnet/api_errno.h>
20 #include <vnet/ip/ip.h>
22 #include <vnet/ipsec/ipsec.h>
23 #include <vnet/ipsec/esp.h>
25 #define ESP_WINDOW_SIZE 64
27 #define foreach_esp_decrypt_next \
28 _(DROP, "error-drop") \
29 _(IP4_INPUT, "ip4-input") \
30 _(IP6_INPUT, "ip6-input")
32 #define _(v, s) ESP_DECRYPT_NEXT_##v,
34 foreach_esp_decrypt_next
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")
49 #define _(sym,str) ESP_DECRYPT_ERROR_##sym,
50 foreach_esp_decrypt_error
53 } esp_decrypt_error_t;
55 static char * esp_decrypt_error_strings[] = {
56 #define _(sym,string) string,
57 foreach_esp_decrypt_error
62 ipsec_crypto_alg_t crypto_alg;
63 ipsec_integ_alg_t integ_alg;
64 } esp_decrypt_trace_t;
66 /* packet trace format function */
67 static u8 * format_esp_decrypt_trace (u8 * s, va_list * args)
69 CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
70 CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
71 esp_decrypt_trace_t * t = va_arg (*args, esp_decrypt_trace_t *);
73 s = format (s, "esp: crypto %U integrity %U",
74 format_ipsec_crypto_alg, t->crypto_alg,
75 format_ipsec_integ_alg, t->integ_alg);
80 esp_decrypt_aes_cbc(ipsec_crypto_alg_t alg,
87 esp_main_t * em = &esp_main;
88 EVP_CIPHER_CTX * ctx = &(em->decrypt_ctx);
89 const EVP_CIPHER * cipher = NULL;
92 ASSERT(alg < IPSEC_CRYPTO_N_ALG);
94 if (PREDICT_FALSE(em->esp_crypto_algs[alg].type == 0))
97 if (PREDICT_FALSE(alg != em->last_decrytp_alg)) {
98 cipher = em->esp_crypto_algs[alg].type;
99 em->last_decrytp_alg = alg;
102 EVP_DecryptInit_ex(ctx, cipher, NULL, key, iv);
104 EVP_DecryptUpdate(ctx, out, &out_len, in, in_len);
105 EVP_DecryptFinal_ex(ctx, out + out_len, &out_len);
109 esp_replay_check (ipsec_sa_t * sa, u32 seq)
113 if (PREDICT_TRUE(seq > sa->last_seq))
116 diff = sa->last_seq - seq;
118 if (ESP_WINDOW_SIZE > diff)
119 return (sa->replay_window & (1ULL << diff)) ? 1 : 0;
127 esp_replay_check_esn (ipsec_sa_t * sa, u32 seq)
129 u32 tl = sa->last_seq;
130 u32 th = sa->last_seq_hi;
133 if (PREDICT_TRUE(tl >= (ESP_WINDOW_SIZE - 1)))
135 if (seq >= (tl - ESP_WINDOW_SIZE + 1))
139 return (sa->replay_window & (1ULL << diff)) ? 1 : 0;
151 if (seq >= (tl - ESP_WINDOW_SIZE + 1))
154 return (sa->replay_window & (1ULL << diff)) ? 1 : 0;
160 return (sa->replay_window & (1ULL << diff)) ? 1 : 0;
170 esp_replay_advance (ipsec_sa_t * sa, u32 seq)
174 if (seq > sa->last_seq)
176 pos = seq - sa->last_seq;
177 if (pos < ESP_WINDOW_SIZE)
178 sa->replay_window = ((sa->replay_window) << pos) | 1;
180 sa->replay_window = 1;
185 pos = sa->last_seq - seq;
186 sa->replay_window |= (1ULL << pos);
191 esp_replay_advance_esn (ipsec_sa_t * sa, u32 seq)
193 int wrap = sa->seq_hi - sa->last_seq_hi;
196 if (wrap == 0 && seq > sa->last_seq)
198 pos = seq - sa->last_seq;
199 if (pos < ESP_WINDOW_SIZE)
200 sa->replay_window = ((sa->replay_window) << pos) | 1;
202 sa->replay_window = 1;
207 pos = ~seq + sa->last_seq + 1;
208 if (pos < ESP_WINDOW_SIZE)
209 sa->replay_window = ((sa->replay_window) << pos) | 1;
211 sa->replay_window = 1;
213 sa->last_seq_hi = sa->seq_hi;
217 pos = ~seq + sa->last_seq + 1;
218 sa->replay_window |= (1ULL << pos);
222 pos = sa->last_seq - seq;
223 sa->replay_window |= (1ULL << pos);
228 esp_decrypt_node_fn (vlib_main_t * vm,
229 vlib_node_runtime_t * node,
230 vlib_frame_t * from_frame)
232 u32 n_left_from, *from, next_index, *to_next;
233 ipsec_main_t *im = &ipsec_main;
234 esp_main_t *em = &esp_main;
236 from = vlib_frame_vector_args (from_frame);
237 n_left_from = from_frame->n_vectors;
239 ipsec_alloc_empty_buffers(vm, im);
241 if (PREDICT_FALSE(vec_len (im->empty_buffers) < n_left_from)){
242 vlib_node_increment_counter (vm, esp_decrypt_node.index,
243 ESP_DECRYPT_ERROR_NO_BUFFER, n_left_from);
244 goto free_buffers_and_exit;
247 next_index = node->cached_next_index;
249 while (n_left_from > 0)
253 vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
255 while (n_left_from > 0 && n_left_to_next > 0)
257 u32 i_bi0, o_bi0 = (u32) ~0, next0;
258 vlib_buffer_t * i_b0;
259 vlib_buffer_t * o_b0 = 0;
270 next0 = ESP_DECRYPT_NEXT_DROP;
272 i_b0 = vlib_get_buffer (vm, i_bi0);
273 esp0 = vlib_buffer_get_current (i_b0);
275 sa_index0 = vnet_buffer(i_b0)->output_features.ipsec_sad_index;
276 sa0 = pool_elt_at_index (im->sad, sa_index0);
278 seq = clib_host_to_net_u32(esp0->seq);
280 /* anti-replay check */
281 if (sa0->use_anti_replay)
285 if (PREDICT_TRUE(sa0->use_esn))
286 rv = esp_replay_check_esn(sa0, seq);
288 rv = esp_replay_check(sa0, seq);
290 if (PREDICT_FALSE(rv))
292 clib_warning("anti-replay SPI %u seq %u", sa0->spi, seq);
293 vlib_node_increment_counter (vm, esp_decrypt_node.index,
294 ESP_DECRYPT_ERROR_REPLAY, 1);
300 if (PREDICT_TRUE(sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
303 int icv_size = em->esp_integ_algs[sa0->integ_alg].trunc_size;
304 memset(sig, 0, sizeof(sig));
305 u8 * icv = vlib_buffer_get_current (i_b0) + i_b0->current_length - icv_size;
306 i_b0->current_length -= icv_size;
308 hmac_calc(sa0->integ_alg, sa0->integ_key, sa0->integ_key_len,
309 (u8 *) esp0, i_b0->current_length, sig, sa0->use_esn,
312 if (PREDICT_FALSE(memcmp(icv, sig, icv_size)))
314 vlib_node_increment_counter (vm, esp_decrypt_node.index,
315 ESP_DECRYPT_ERROR_INTEG_ERROR, 1);
321 if (PREDICT_TRUE(sa0->use_anti_replay))
323 if (PREDICT_TRUE(sa0->use_esn))
324 esp_replay_advance_esn(sa0, seq);
326 esp_replay_advance(sa0, seq);
329 /* grab free buffer */
330 uword last_empty_buffer = vec_len (im->empty_buffers) - 1;
331 o_bi0 = im->empty_buffers[last_empty_buffer];
332 o_b0 = vlib_get_buffer (vm, o_bi0);
333 vlib_prefetch_buffer_with_index (vm, im->empty_buffers[last_empty_buffer-1], STORE);
334 _vec_len (im->empty_buffers) = last_empty_buffer;
336 /* add old buffer to the recycle list */
337 vec_add1(recycle, i_bi0);
339 if (sa0->crypto_alg >= IPSEC_CRYPTO_ALG_AES_CBC_128 &&
340 sa0->crypto_alg <= IPSEC_CRYPTO_ALG_AES_CBC_256) {
341 const int BLOCK_SIZE = 16;
342 const int IV_SIZE = 16;
345 int blocks = (i_b0->current_length - sizeof (esp_header_t) - IV_SIZE) / BLOCK_SIZE;
347 o_b0->current_data = sizeof(ethernet_header_t);
349 esp_decrypt_aes_cbc(sa0->crypto_alg,
350 esp0->data + IV_SIZE,
351 (u8 *) vlib_buffer_get_current (o_b0),
356 o_b0->current_length = (blocks * 16) - 2;
357 o_b0->flags = VLIB_BUFFER_TOTAL_LENGTH_VALID;
358 f0 = (esp_footer_t *) ((u8 *) vlib_buffer_get_current (o_b0) + o_b0->current_length);
359 o_b0->current_length -= f0->pad_length;
360 if (PREDICT_TRUE(f0->next_header == IP_PROTOCOL_IP_IN_IP))
361 next0 = ESP_DECRYPT_NEXT_IP4_INPUT;
362 else if (f0->next_header == IP_PROTOCOL_IPV6)
363 next0 = ESP_DECRYPT_NEXT_IP6_INPUT;
366 clib_warning("next header: 0x%x", f0->next_header);
367 vlib_node_increment_counter (vm, esp_decrypt_node.index,
368 ESP_DECRYPT_ERROR_DECRYPTION_FAILED,
377 vnet_buffer (o_b0)->sw_if_index[VLIB_TX] = (u32)~0;
381 if (PREDICT_FALSE(i_b0->flags & VLIB_BUFFER_IS_TRACED)) {
383 o_b0->flags |= VLIB_BUFFER_IS_TRACED;
384 o_b0->trace_index = i_b0->trace_index;
386 esp_decrypt_trace_t *tr = vlib_add_trace (vm, node, o_b0, sizeof (*tr));
387 tr->crypto_alg = sa0->crypto_alg;
388 tr->integ_alg = sa0->integ_alg;
391 vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
392 n_left_to_next, o_bi0, next0);
394 vlib_put_next_frame (vm, node, next_index, n_left_to_next);
396 vlib_node_increment_counter (vm, esp_decrypt_node.index,
397 ESP_DECRYPT_ERROR_RX_PKTS,
398 from_frame->n_vectors);
400 free_buffers_and_exit:
401 vlib_buffer_free (vm, recycle, vec_len(recycle));
403 return from_frame->n_vectors;
407 VLIB_REGISTER_NODE (esp_decrypt_node) = {
408 .function = esp_decrypt_node_fn,
409 .name = "esp-decrypt",
410 .vector_size = sizeof (u32),
411 .format_trace = format_esp_decrypt_trace,
412 .type = VLIB_NODE_TYPE_INTERNAL,
414 .n_errors = ARRAY_LEN(esp_decrypt_error_strings),
415 .error_strings = esp_decrypt_error_strings,
417 .n_next_nodes = ESP_DECRYPT_N_NEXT,
419 #define _(s,n) [ESP_DECRYPT_NEXT_##s] = n,
420 foreach_esp_decrypt_next