2 * esp_decrypt.c : IPSec ESP Decrypt node using DPDK Cryptodev
4 * Copyright (c) 2017 Intel 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 opy 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>
24 #include <dpdk/buffer.h>
25 #include <dpdk/ipsec/ipsec.h>
26 #include <dpdk/device/dpdk.h>
27 #include <dpdk/device/dpdk_priv.h>
29 #define foreach_esp_decrypt_next \
30 _(DROP, "error-drop") \
31 _(IP4_INPUT, "ip4-input-no-checksum") \
32 _(IP6_INPUT, "ip6-input")
34 #define _(v, s) ESP_DECRYPT_NEXT_##v,
37 foreach_esp_decrypt_next
42 #define foreach_esp_decrypt_error \
43 _(RX_PKTS, "ESP pkts received") \
44 _(DECRYPTION_FAILED, "ESP decryption failed") \
45 _(REPLAY, "SA replayed packet") \
46 _(NOT_IP, "Not IP packet (dropped)") \
47 _(ENQ_FAIL, "Enqueue failed (buffer full)") \
48 _(DISCARD, "Not enough crypto operations, discarding frame") \
49 _(BAD_LEN, "Invalid ciphertext length") \
50 _(SESSION, "Failed to get crypto session") \
51 _(NOSUP, "Cipher/Auth not supported")
56 #define _(sym,str) ESP_DECRYPT_ERROR_##sym,
57 foreach_esp_decrypt_error
60 } esp_decrypt_error_t;
62 static char *esp_decrypt_error_strings[] = {
63 #define _(sym,string) string,
64 foreach_esp_decrypt_error
68 extern vlib_node_registration_t dpdk_esp4_decrypt_node;
69 extern vlib_node_registration_t dpdk_esp6_decrypt_node;
73 ipsec_crypto_alg_t crypto_alg;
74 ipsec_integ_alg_t integ_alg;
76 } esp_decrypt_trace_t;
78 /* packet trace format function */
80 format_esp_decrypt_trace (u8 * s, va_list * args)
82 CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
83 CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
84 esp_decrypt_trace_t *t = va_arg (*args, esp_decrypt_trace_t *);
85 u32 indent = format_get_indent (s);
87 s = format (s, "cipher %U auth %U\n",
88 format_ipsec_crypto_alg, t->crypto_alg,
89 format_ipsec_integ_alg, t->integ_alg);
90 s = format (s, "%U%U",
91 format_white_space, indent, format_esp_header, t->packet_data);
96 dpdk_esp_decrypt_inline (vlib_main_t * vm,
97 vlib_node_runtime_t * node,
98 vlib_frame_t * from_frame, int is_ip6)
100 u32 n_left_from, *from, *to_next, next_index, thread_index;
101 ipsec_main_t *im = &ipsec_main;
102 u32 thread_idx = vlib_get_thread_index ();
103 dpdk_crypto_main_t *dcm = &dpdk_crypto_main;
104 crypto_resource_t *res = 0;
106 crypto_alg_t *cipher_alg = 0, *auth_alg = 0;
107 struct rte_cryptodev_sym_session *session = 0;
108 u32 ret, last_sa_index = ~0;
109 u8 numa = rte_socket_id ();
111 crypto_worker_main_t *cwm =
112 vec_elt_at_index (dcm->workers_main, thread_idx);
113 struct rte_crypto_op **ops = cwm->ops;
115 from = vlib_frame_vector_args (from_frame);
116 n_left_from = from_frame->n_vectors;
117 thread_index = vm->thread_index;
119 ret = crypto_alloc_ops (numa, ops, n_left_from);
123 vlib_node_increment_counter (vm, dpdk_esp6_decrypt_node.index,
124 ESP_DECRYPT_ERROR_DISCARD, 1);
126 vlib_node_increment_counter (vm, dpdk_esp4_decrypt_node.index,
127 ESP_DECRYPT_ERROR_DISCARD, 1);
128 /* Discard whole frame */
132 next_index = ESP_DECRYPT_NEXT_DROP;
134 while (n_left_from > 0)
138 vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
140 while (n_left_from > 0 && n_left_to_next > 0)
143 u32 bi0, sa_index0, iv_size;
147 struct rte_mbuf *mb0;
148 struct rte_crypto_op *op;
155 b0 = vlib_get_buffer (vm, bi0);
156 mb0 = rte_mbuf_from_vlib_buffer (b0);
157 esp0 = vlib_buffer_get_current (b0);
160 CLIB_PREFETCH (esp0, sizeof (esp0[0]) + 16, LOAD);
162 CLIB_PREFETCH (mb0, CLIB_CACHE_LINE_BYTES, STORE);
166 ASSERT (op->status == RTE_CRYPTO_OP_STATUS_NOT_PROCESSED);
168 dpdk_op_priv_t *priv = crypto_op_get_priv (op);
169 /* store bi in op private */
173 sizeof (op[0]) + sizeof (op[0].sym[0]) + sizeof (priv[0]);
174 CLIB_PREFETCH (op, op_len, STORE);
176 sa_index0 = vnet_buffer (b0)->ipsec.sad_index;
177 vlib_prefetch_combined_counter (&ipsec_sa_counters,
178 thread_index, sa_index0);
180 if (sa_index0 != last_sa_index)
182 sa0 = pool_elt_at_index (im->sad, sa_index0);
185 vec_elt_at_index (dcm->cipher_algs, sa0->crypto_alg);
186 auth_alg = vec_elt_at_index (dcm->auth_algs, sa0->integ_alg);
188 is_aead = (cipher_alg->type == RTE_CRYPTO_SYM_XFORM_AEAD);
190 auth_alg = cipher_alg;
192 res_idx = get_resource (cwm, sa0);
194 if (PREDICT_FALSE (res_idx == (u16) ~ 0))
196 clib_warning ("unsupported SA by thread index %u",
199 vlib_node_increment_counter (vm,
200 dpdk_esp6_decrypt_node.index,
201 ESP_DECRYPT_ERROR_NOSUP, 1);
203 vlib_node_increment_counter (vm,
204 dpdk_esp4_decrypt_node.index,
205 ESP_DECRYPT_ERROR_NOSUP, 1);
211 res = vec_elt_at_index (dcm->resource, res_idx);
213 error = crypto_get_session (&session, sa_index0, res, cwm, 0);
214 if (PREDICT_FALSE (error || !session))
216 clib_warning ("failed to get crypto session");
218 vlib_node_increment_counter (vm,
219 dpdk_esp6_decrypt_node.index,
220 ESP_DECRYPT_ERROR_SESSION,
223 vlib_node_increment_counter (vm,
224 dpdk_esp4_decrypt_node.index,
225 ESP_DECRYPT_ERROR_SESSION,
233 last_sa_index = sa_index0;
236 /* anti-replay check */
237 if (ipsec_sa_anti_replay_check (sa0, &esp0->seq))
239 clib_warning ("failed anti-replay check");
241 vlib_node_increment_counter (vm,
242 dpdk_esp6_decrypt_node.index,
243 ESP_DECRYPT_ERROR_REPLAY, 1);
245 vlib_node_increment_counter (vm,
246 dpdk_esp4_decrypt_node.index,
247 ESP_DECRYPT_ERROR_REPLAY, 1);
255 priv->next = DPDK_CRYPTO_INPUT_NEXT_DECRYPT6_POST;
257 priv->next = DPDK_CRYPTO_INPUT_NEXT_DECRYPT4_POST;
259 /* FIXME multi-seg */
260 vlib_increment_combined_counter
261 (&ipsec_sa_counters, thread_index, sa_index0,
262 1, b0->current_length);
264 res->ops[res->n_ops] = op;
265 res->bi[res->n_ops] = bi0;
268 /* Convert vlib buffer to mbuf */
269 mb0->data_len = b0->current_length;
270 mb0->pkt_len = b0->current_length;
271 mb0->data_off = RTE_PKTMBUF_HEADROOM + b0->current_data;
273 trunc_size = auth_alg->trunc_size;
274 iv_size = cipher_alg->iv_len;
276 /* Outer IP header has already been stripped */
278 b0->current_length - sizeof (esp_header_t) - iv_size - trunc_size;
280 ASSERT (payload_len >= 4);
282 if (payload_len & (cipher_alg->boundary - 1))
284 clib_warning ("payload %u not multiple of %d\n",
285 payload_len, cipher_alg->boundary);
287 vlib_node_increment_counter (vm, dpdk_esp6_decrypt_node.index,
288 ESP_DECRYPT_ERROR_BAD_LEN, 1);
290 vlib_node_increment_counter (vm, dpdk_esp4_decrypt_node.index,
291 ESP_DECRYPT_ERROR_BAD_LEN, 1);
299 u32 cipher_off, cipher_len;
303 u8 *iv = (u8 *) (esp0 + 1);
305 dpdk_gcm_cnt_blk *icb = &priv->cb;
307 cipher_off = sizeof (esp_header_t) + iv_size;
308 cipher_len = payload_len;
310 u8 *digest = vlib_buffer_get_tail (b0) - trunc_size;
312 mb0->buf_physaddr + digest - ((u8 *) mb0->buf_addr);
314 if (!is_aead && cipher_alg->alg == RTE_CRYPTO_CIPHER_AES_CBC)
315 clib_memcpy_fast (icb, iv, 16);
318 u32 *_iv = (u32 *) iv;
320 crypto_set_icb (icb, sa0->salt, _iv[0], _iv[1]);
326 u32 *_aad = (u32 *) aad;
327 clib_memcpy_fast (aad, esp0, 8);
329 /* _aad[3] should always be 0 */
330 if (PREDICT_FALSE (ipsec_sa_is_set_USE_EXTENDED_SEQ_NUM (sa0)))
331 _aad[2] = clib_host_to_net_u32 (sa0->seq_hi);
337 auth_len = sizeof (esp_header_t) + iv_size + payload_len;
339 if (ipsec_sa_is_set_USE_EXTENDED_SEQ_NUM (sa0))
341 clib_memcpy_fast (priv->icv, digest, trunc_size);
342 u32 *_digest = (u32 *) digest;
343 _digest[0] = clib_host_to_net_u32 (sa0->seq_hi);
344 auth_len += sizeof (sa0->seq_hi);
348 op->phys_addr + (uintptr_t) priv->icv - (uintptr_t) op;
352 crypto_op_setup (is_aead, mb0, op, session, cipher_off, cipher_len,
353 0, auth_len, aad, digest, digest_paddr);
355 if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
357 esp_decrypt_trace_t *tr =
358 vlib_add_trace (vm, node, b0, sizeof (*tr));
359 tr->crypto_alg = sa0->crypto_alg;
360 tr->integ_alg = sa0->integ_alg;
361 clib_memcpy_fast (tr->packet_data, vlib_buffer_get_current (b0),
362 sizeof (esp_header_t));
365 vlib_put_next_frame (vm, node, next_index, n_left_to_next);
370 vlib_node_increment_counter (vm, dpdk_esp6_decrypt_node.index,
371 ESP_DECRYPT_ERROR_RX_PKTS,
372 from_frame->n_vectors);
374 crypto_enqueue_ops (vm, cwm, dpdk_esp6_decrypt_node.index,
375 ESP_DECRYPT_ERROR_ENQ_FAIL, numa);
379 vlib_node_increment_counter (vm, dpdk_esp4_decrypt_node.index,
380 ESP_DECRYPT_ERROR_RX_PKTS,
381 from_frame->n_vectors);
383 crypto_enqueue_ops (vm, cwm, dpdk_esp4_decrypt_node.index,
384 ESP_DECRYPT_ERROR_ENQ_FAIL, numa);
387 crypto_free_ops (numa, ops, cwm->ops + from_frame->n_vectors - ops);
389 return from_frame->n_vectors;
392 VLIB_NODE_FN (dpdk_esp4_decrypt_node) (vlib_main_t * vm,
393 vlib_node_runtime_t * node,
394 vlib_frame_t * from_frame)
396 return dpdk_esp_decrypt_inline (vm, node, from_frame, 0 /*is_ip6 */ );
400 VLIB_REGISTER_NODE (dpdk_esp4_decrypt_node) = {
401 .name = "dpdk-esp4-decrypt",
402 .vector_size = sizeof (u32),
403 .format_trace = format_esp_decrypt_trace,
404 .type = VLIB_NODE_TYPE_INTERNAL,
406 .n_errors = ARRAY_LEN(esp_decrypt_error_strings),
407 .error_strings = esp_decrypt_error_strings,
409 .n_next_nodes = ESP_DECRYPT_N_NEXT,
411 #define _(s,n) [ESP_DECRYPT_NEXT_##s] = n,
412 foreach_esp_decrypt_next
418 VLIB_NODE_FN (dpdk_esp6_decrypt_node) (vlib_main_t * vm,
419 vlib_node_runtime_t * node,
420 vlib_frame_t * from_frame)
422 return dpdk_esp_decrypt_inline (vm, node, from_frame, 1 /*is_ip6 */ );
426 VLIB_REGISTER_NODE (dpdk_esp6_decrypt_node) = {
427 .name = "dpdk-esp6-decrypt",
428 .vector_size = sizeof (u32),
429 .format_trace = format_esp_decrypt_trace,
430 .type = VLIB_NODE_TYPE_INTERNAL,
432 .n_errors = ARRAY_LEN(esp_decrypt_error_strings),
433 .error_strings = esp_decrypt_error_strings,
435 .n_next_nodes = ESP_DECRYPT_N_NEXT,
437 #define _(s,n) [ESP_DECRYPT_NEXT_##s] = n,
438 foreach_esp_decrypt_next
448 #define foreach_esp_decrypt_post_error \
449 _(PKTS, "ESP post pkts")
453 #define _(sym,str) ESP_DECRYPT_POST_ERROR_##sym,
454 foreach_esp_decrypt_post_error
456 ESP_DECRYPT_POST_N_ERROR,
457 } esp_decrypt_post_error_t;
459 static char *esp_decrypt_post_error_strings[] = {
460 #define _(sym,string) string,
461 foreach_esp_decrypt_post_error
465 extern vlib_node_registration_t dpdk_esp4_decrypt_post_node;
466 extern vlib_node_registration_t dpdk_esp6_decrypt_post_node;
469 format_esp_decrypt_post_trace (u8 * s, va_list * args)
471 CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
472 CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
473 esp_decrypt_trace_t *t = va_arg (*args, esp_decrypt_trace_t *);
474 u32 indent = format_get_indent (s);
476 s = format (s, "cipher %U auth %U\n",
477 format_ipsec_crypto_alg, t->crypto_alg,
478 format_ipsec_integ_alg, t->integ_alg);
480 ip4_header_t *ih4 = (ip4_header_t *) t->packet_data;
481 if ((ih4->ip_version_and_header_length & 0xF0) == 0x60)
483 format (s, "%U%U", format_white_space, indent, format_ip6_header, ih4);
486 format (s, "%U%U", format_white_space, indent, format_ip4_header, ih4);
492 dpdk_esp_decrypt_post_inline (vlib_main_t * vm,
493 vlib_node_runtime_t * node,
494 vlib_frame_t * from_frame, int is_ip6)
496 u32 n_left_from, *from, *to_next = 0, next_index;
499 ipsec_main_t *im = &ipsec_main;
500 dpdk_crypto_main_t *dcm = &dpdk_crypto_main;
502 from = vlib_frame_vector_args (from_frame);
503 n_left_from = from_frame->n_vectors;
505 next_index = node->cached_next_index;
507 while (n_left_from > 0)
511 vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
513 while (n_left_from > 0 && n_left_to_next > 0)
516 u32 bi0, iv_size, next0;
517 vlib_buffer_t *b0 = 0;
518 ip4_header_t *ih4 = 0, *oh4 = 0;
519 ip6_header_t *ih6 = 0, *oh6 = 0;
520 crypto_alg_t *cipher_alg, *auth_alg;
522 u8 trunc_size, is_aead;
523 u16 udp_encap_adv = 0;
525 next0 = ESP_DECRYPT_NEXT_DROP;
532 b0 = vlib_get_buffer (vm, bi0);
533 esp0 = vlib_buffer_get_current (b0);
535 sa_index0 = vnet_buffer (b0)->ipsec.sad_index;
536 sa0 = pool_elt_at_index (im->sad, sa_index0);
541 cipher_alg = vec_elt_at_index (dcm->cipher_algs, sa0->crypto_alg);
542 auth_alg = vec_elt_at_index (dcm->auth_algs, sa0->integ_alg);
543 is_aead = cipher_alg->type == RTE_CRYPTO_SYM_XFORM_AEAD;
545 auth_alg = cipher_alg;
547 trunc_size = auth_alg->trunc_size;
549 iv_size = cipher_alg->iv_len;
551 ipsec_sa_anti_replay_advance (sa0, &esp0->seq);
553 /* if UDP encapsulation is used adjust the address of the IP header */
554 if (ipsec_sa_is_set_UDP_ENCAP (sa0)
555 && (b0->flags & VNET_BUFFER_F_IS_IP4))
557 udp_encap_adv = sizeof (udp_header_t);
560 if (b0->flags & VNET_BUFFER_F_IS_IP4)
561 ih4 = (ip4_header_t *)
562 ((u8 *) esp0 - udp_encap_adv - sizeof (ip4_header_t));
564 ih4 = (ip4_header_t *) ((u8 *) esp0 - sizeof (ip6_header_t));
566 vlib_buffer_advance (b0, sizeof (esp_header_t) + iv_size);
568 b0->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
569 f0 = (esp_footer_t *) (vlib_buffer_get_tail (b0) - trunc_size - 2);
570 b0->current_length -= (f0->pad_length + trunc_size + 2);
573 const u8 *padding = vlib_buffer_get_tail (b0);
574 if (PREDICT_FALSE (memcmp (padding, pad_data, f0->pad_length)))
576 clib_warning ("bad padding");
577 vlib_node_increment_counter (vm, dpdk_esp_decrypt_node.index,
578 ESP_DECRYPT_ERROR_DECRYPTION_FAILED,
583 if (ipsec_sa_is_set_IS_TUNNEL (sa0))
585 if (f0->next_header == IP_PROTOCOL_IP_IN_IP)
586 next0 = ESP_DECRYPT_NEXT_IP4_INPUT;
587 else if (ipsec_sa_is_set_IS_TUNNEL_V6 (sa0)
588 && f0->next_header == IP_PROTOCOL_IPV6)
589 next0 = ESP_DECRYPT_NEXT_IP6_INPUT;
592 clib_warning ("next header: 0x%x", f0->next_header);
594 vlib_node_increment_counter (vm,
595 dpdk_esp6_decrypt_node.index,
596 ESP_DECRYPT_ERROR_DECRYPTION_FAILED,
599 vlib_node_increment_counter (vm,
600 dpdk_esp4_decrypt_node.index,
601 ESP_DECRYPT_ERROR_DECRYPTION_FAILED,
606 else /* transport mode */
608 if ((ih4->ip_version_and_header_length & 0xF0) == 0x40)
610 u16 ih4_len = ip4_header_bytes (ih4);
611 vlib_buffer_advance (b0, -ih4_len - udp_encap_adv);
612 next0 = ESP_DECRYPT_NEXT_IP4_INPUT;
613 if (!ipsec_sa_is_set_UDP_ENCAP (sa0))
615 oh4 = vlib_buffer_get_current (b0);
616 memmove (oh4, ih4, ih4_len);
617 oh4->protocol = f0->next_header;
618 oh4->length = clib_host_to_net_u16 (b0->current_length);
619 oh4->checksum = ip4_header_checksum (oh4);
622 else if ((ih4->ip_version_and_header_length & 0xF0) == 0x60)
624 ih6 = (ip6_header_t *) ih4;
625 vlib_buffer_advance (b0, -sizeof (ip6_header_t));
626 oh6 = vlib_buffer_get_current (b0);
627 memmove (oh6, ih6, sizeof (ip6_header_t));
629 next0 = ESP_DECRYPT_NEXT_IP6_INPUT;
630 oh6->protocol = f0->next_header;
631 u16 len = b0->current_length - sizeof (ip6_header_t);
632 oh6->payload_length = clib_host_to_net_u16 (len);
636 clib_warning ("next header: 0x%x", f0->next_header);
638 vlib_node_increment_counter (vm,
639 dpdk_esp6_decrypt_node.index,
640 ESP_DECRYPT_ERROR_DECRYPTION_FAILED,
643 vlib_node_increment_counter (vm,
644 dpdk_esp4_decrypt_node.index,
645 ESP_DECRYPT_ERROR_DECRYPTION_FAILED,
651 vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
654 if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
656 esp_decrypt_trace_t *tr =
657 vlib_add_trace (vm, node, b0, sizeof (*tr));
658 tr->crypto_alg = sa0->crypto_alg;
659 tr->integ_alg = sa0->integ_alg;
660 ih4 = vlib_buffer_get_current (b0);
661 clib_memcpy_fast (tr->packet_data, ih4, sizeof (ip6_header_t));
664 vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
665 to_next, n_left_to_next, bi0,
668 vlib_put_next_frame (vm, node, next_index, n_left_to_next);
672 vlib_node_increment_counter (vm, dpdk_esp6_decrypt_post_node.index,
673 ESP_DECRYPT_POST_ERROR_PKTS,
674 from_frame->n_vectors);
676 vlib_node_increment_counter (vm, dpdk_esp4_decrypt_post_node.index,
677 ESP_DECRYPT_POST_ERROR_PKTS,
678 from_frame->n_vectors);
680 return from_frame->n_vectors;
683 VLIB_NODE_FN (dpdk_esp4_decrypt_post_node) (vlib_main_t * vm,
684 vlib_node_runtime_t * node,
685 vlib_frame_t * from_frame)
687 return dpdk_esp_decrypt_post_inline (vm, node, from_frame, 0 /*is_ip6 */ );
691 VLIB_REGISTER_NODE (dpdk_esp4_decrypt_post_node) = {
692 .name = "dpdk-esp4-decrypt-post",
693 .vector_size = sizeof (u32),
694 .format_trace = format_esp_decrypt_post_trace,
695 .type = VLIB_NODE_TYPE_INTERNAL,
697 .n_errors = ARRAY_LEN(esp_decrypt_post_error_strings),
698 .error_strings = esp_decrypt_post_error_strings,
700 .n_next_nodes = ESP_DECRYPT_N_NEXT,
702 #define _(s,n) [ESP_DECRYPT_NEXT_##s] = n,
703 foreach_esp_decrypt_next
709 VLIB_NODE_FN (dpdk_esp6_decrypt_post_node) (vlib_main_t * vm,
710 vlib_node_runtime_t * node,
711 vlib_frame_t * from_frame)
713 return dpdk_esp_decrypt_post_inline (vm, node, from_frame, 0 /*is_ip6 */ );
717 VLIB_REGISTER_NODE (dpdk_esp6_decrypt_post_node) = {
718 .name = "dpdk-esp6-decrypt-post",
719 .vector_size = sizeof (u32),
720 .format_trace = format_esp_decrypt_post_trace,
721 .type = VLIB_NODE_TYPE_INTERNAL,
723 .n_errors = ARRAY_LEN(esp_decrypt_post_error_strings),
724 .error_strings = esp_decrypt_post_error_strings,
726 .n_next_nodes = ESP_DECRYPT_N_NEXT,
728 #define _(s,n) [ESP_DECRYPT_NEXT_##s] = n,
729 foreach_esp_decrypt_next
736 * fd.io coding-style-patch-verification: ON
739 * eval: (c-set-style "gnu")