43a3c2a973837e5c8c27dfdfeb55fddf992ae19d
[strongswan.git] / src / libipsec / esp_packet.c
1 /*
2 * Copyright (C) 2012 Tobias Brunner
3 * Copyright (C) 2012 Giuliano Grassi
4 * Copyright (C) 2012 Ralf Sager
5 * Hochschule fuer Technik Rapperswil
6 *
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License as published by the
9 * Free Software Foundation; either version 2 of the License, or (at your
10 * option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
11 *
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * for more details.
16 */
17
18
19 #include "esp_packet.h"
20
21 #include <library.h>
22 #include <utils/debug.h>
23 #include <crypto/crypters/crypter.h>
24 #include <crypto/signers/signer.h>
25 #include <bio/bio_reader.h>
26 #include <bio/bio_writer.h>
27
28 #include <netinet/in.h>
29
30 typedef struct private_esp_packet_t private_esp_packet_t;
31
32 /**
33 * Private additions to esp_packet_t.
34 */
35 struct private_esp_packet_t {
36
37 /**
38 * Public members
39 */
40 esp_packet_t public;
41
42 /**
43 * Raw ESP packet
44 */
45 packet_t *packet;
46
47 /**
48 * Payload of this packet
49 */
50 ip_packet_t *payload;
51
52 /**
53 * Next Header info (e.g. IPPROTO_IPIP)
54 */
55 u_int8_t next_header;
56
57 };
58
59 /**
60 * Forward declaration for clone()
61 */
62 static private_esp_packet_t *esp_packet_create_internal(packet_t *packet);
63
64 METHOD(packet_t, set_source, void,
65 private_esp_packet_t *this, host_t *src)
66 {
67 return this->packet->set_source(this->packet, src);
68 }
69
70 METHOD2(esp_packet_t, packet_t, get_source, host_t*,
71 private_esp_packet_t *this)
72 {
73 return this->packet->get_source(this->packet);
74 }
75
76 METHOD(packet_t, set_destination, void,
77 private_esp_packet_t *this, host_t *dst)
78 {
79 return this->packet->set_destination(this->packet, dst);
80 }
81
82 METHOD2(esp_packet_t, packet_t, get_destination, host_t*,
83 private_esp_packet_t *this)
84 {
85 return this->packet->get_destination(this->packet);
86 }
87
88 METHOD(packet_t, get_data, chunk_t,
89 private_esp_packet_t *this)
90 {
91 return this->packet->get_data(this->packet);
92 }
93
94 METHOD(packet_t, set_data, void,
95 private_esp_packet_t *this, chunk_t data)
96 {
97 return this->packet->set_data(this->packet, data);
98 }
99
100 METHOD(packet_t, get_dscp, u_int8_t,
101 private_esp_packet_t *this)
102 {
103 return this->packet->get_dscp(this->packet);
104 }
105
106 METHOD(packet_t, set_dscp, void,
107 private_esp_packet_t *this, u_int8_t value)
108 {
109 this->packet->set_dscp(this->packet, value);
110 }
111
112 METHOD(packet_t, skip_bytes, void,
113 private_esp_packet_t *this, size_t bytes)
114 {
115 return this->packet->skip_bytes(this->packet, bytes);
116 }
117
118 METHOD(packet_t, clone, packet_t*,
119 private_esp_packet_t *this)
120 {
121 private_esp_packet_t *pkt;
122
123 pkt = esp_packet_create_internal(this->packet->clone(this->packet));
124 pkt->payload = this->payload ? this->payload->clone(this->payload) : NULL;
125 pkt->next_header = this->next_header;
126 return &pkt->public.packet;
127 }
128
129 METHOD(esp_packet_t, parse_header, bool,
130 private_esp_packet_t *this, u_int32_t *spi)
131 {
132 bio_reader_t *reader;
133 u_int32_t seq;
134
135 reader = bio_reader_create(this->packet->get_data(this->packet));
136 if (!reader->read_uint32(reader, spi) ||
137 !reader->read_uint32(reader, &seq))
138 {
139 DBG1(DBG_ESP, "failed to parse ESP header: invalid length");
140 reader->destroy(reader);
141 return FALSE;
142 }
143 reader->destroy(reader);
144
145 DBG2(DBG_ESP, "parsed ESP header with SPI %.8x [seq %u]", *spi, seq);
146 *spi = htonl(*spi);
147 return TRUE;
148 }
149
150 /**
151 * Check padding as specified in RFC 4303
152 */
153 static bool check_padding(chunk_t padding)
154 {
155 size_t i;
156
157 for (i = 0; i < padding.len; ++i)
158 {
159 if (padding.ptr[i] != (u_int8_t)(i + 1))
160 {
161 return FALSE;
162 }
163 }
164 return TRUE;
165 }
166
167 /**
168 * Remove the padding from the payload and set the next header info
169 */
170 static bool remove_padding(private_esp_packet_t *this, chunk_t plaintext)
171 {
172 u_int8_t next_header, pad_length;
173 chunk_t padding, payload;
174 bio_reader_t *reader;
175
176 reader = bio_reader_create(plaintext);
177 if (!reader->read_uint8_end(reader, &next_header) ||
178 !reader->read_uint8_end(reader, &pad_length))
179 {
180 DBG1(DBG_ESP, "parsing ESP payload failed: invalid length");
181 goto failed;
182 }
183 if (!reader->read_data_end(reader, pad_length, &padding) ||
184 !check_padding(padding))
185 {
186 DBG1(DBG_ESP, "parsing ESP payload failed: invalid padding");
187 goto failed;
188 }
189 this->payload = ip_packet_create(reader->peek(reader));
190 reader->destroy(reader);
191 if (!this->payload)
192 {
193 DBG1(DBG_ESP, "parsing ESP payload failed: unsupported payload");
194 return FALSE;
195 }
196 this->next_header = next_header;
197 payload = this->payload->get_encoding(this->payload);
198
199 DBG3(DBG_ESP, "ESP payload:\n payload %B\n padding %B\n "
200 "padding length = %hhu, next header = %hhu", &payload, &padding,
201 pad_length, this->next_header);
202 return TRUE;
203
204 failed:
205 reader->destroy(reader);
206 chunk_free(&plaintext);
207 return FALSE;
208 }
209
210 METHOD(esp_packet_t, decrypt, status_t,
211 private_esp_packet_t *this, esp_context_t *esp_context)
212 {
213 bio_reader_t *reader;
214 u_int32_t spi, seq;
215 chunk_t data, iv, icv, ciphertext, plaintext;
216 crypter_t *crypter;
217 signer_t *signer;
218
219 DESTROY_IF(this->payload);
220 this->payload = NULL;
221
222 data = this->packet->get_data(this->packet);
223 crypter = esp_context->get_crypter(esp_context);
224 signer = esp_context->get_signer(esp_context);
225
226 reader = bio_reader_create(data);
227 if (!reader->read_uint32(reader, &spi) ||
228 !reader->read_uint32(reader, &seq) ||
229 !reader->read_data(reader, crypter->get_iv_size(crypter), &iv) ||
230 !reader->read_data_end(reader, signer->get_block_size(signer), &icv) ||
231 reader->remaining(reader) % crypter->get_block_size(crypter))
232 {
233 DBG1(DBG_ESP, "ESP decryption failed: invalid length");
234 return PARSE_ERROR;
235 }
236 ciphertext = reader->peek(reader);
237 reader->destroy(reader);
238
239 if (!esp_context->verify_seqno(esp_context, seq))
240 {
241 DBG1(DBG_ESP, "ESP sequence number verification failed:\n "
242 "src %H, dst %H, SPI %.8x [seq %u]",
243 get_source(this), get_destination(this), spi, seq);
244 return VERIFY_ERROR;
245 }
246 DBG3(DBG_ESP, "ESP decryption:\n SPI %.8x [seq %u]\n IV %B\n "
247 "encrypted %B\n ICV %B", spi, seq, &iv, &ciphertext, &icv);
248
249 if (!signer->get_signature(signer, chunk_create(data.ptr, 8), NULL) ||
250 !signer->get_signature(signer, iv, NULL) ||
251 !signer->verify_signature(signer, ciphertext, icv))
252 {
253 DBG1(DBG_ESP, "ICV verification failed!");
254 return FAILED;
255 }
256 esp_context->set_authenticated_seqno(esp_context, seq);
257
258 if (!crypter->decrypt(crypter, ciphertext, iv, &plaintext))
259 {
260 DBG1(DBG_ESP, "ESP decryption failed");
261 return FAILED;
262 }
263
264 if (!remove_padding(this, plaintext))
265 {
266 return PARSE_ERROR;
267 }
268 return SUCCESS;
269 }
270
271 /**
272 * Generate the padding as specified in RFC4303
273 */
274 static void generate_padding(chunk_t padding)
275 {
276 size_t i;
277
278 for (i = 0; i < padding.len; ++i)
279 {
280 padding.ptr[i] = (u_int8_t)(i + 1);
281 }
282 }
283
284 METHOD(esp_packet_t, encrypt, status_t,
285 private_esp_packet_t *this, esp_context_t *esp_context, u_int32_t spi)
286 {
287 chunk_t iv, icv, padding, payload, ciphertext, auth_data;
288 bio_writer_t *writer;
289 u_int32_t next_seqno;
290 size_t blocksize, plainlen;
291 crypter_t *crypter;
292 signer_t *signer;
293 rng_t *rng;
294
295 this->packet->set_data(this->packet, chunk_empty);
296
297 if (!esp_context->next_seqno(esp_context, &next_seqno))
298 {
299 DBG1(DBG_ESP, "ESP encapsulation failed: sequence numbers cycled");
300 return FAILED;
301 }
302
303 rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK);
304 if (!rng)
305 {
306 DBG1(DBG_ESP, "ESP encryption failed: could not find RNG");
307 return NOT_FOUND;
308 }
309 crypter = esp_context->get_crypter(esp_context);
310 signer = esp_context->get_signer(esp_context);
311
312 blocksize = crypter->get_block_size(crypter);
313 iv.len = crypter->get_iv_size(crypter);
314 icv.len = signer->get_block_size(signer);
315
316 /* plaintext = payload, padding, pad_length, next_header */
317 payload = this->payload ? this->payload->get_encoding(this->payload)
318 : chunk_empty;
319 plainlen = payload.len + 2;
320 padding.len = blocksize - (plainlen % blocksize);
321 plainlen += padding.len;
322
323 /* len = spi, seq, IV, plaintext, ICV */
324 writer = bio_writer_create(2 * sizeof(u_int32_t) + iv.len + plainlen +
325 icv.len);
326 writer->write_uint32(writer, ntohl(spi));
327 writer->write_uint32(writer, next_seqno);
328
329 iv = writer->skip(writer, iv.len);
330 if (!rng->get_bytes(rng, iv.len, iv.ptr))
331 {
332 DBG1(DBG_ESP, "ESP encryption failed: could not generate IV");
333 writer->destroy(writer);
334 rng->destroy(rng);
335 return FAILED;
336 }
337 rng->destroy(rng);
338
339 /* plain-/ciphertext will start here */
340 ciphertext = writer->get_buf(writer);
341 ciphertext.ptr += ciphertext.len;
342 ciphertext.len = plainlen;
343
344 writer->write_data(writer, payload);
345
346 padding = writer->skip(writer, padding.len);
347 generate_padding(padding);
348
349 writer->write_uint8(writer, padding.len);
350 writer->write_uint8(writer, this->next_header);
351
352 DBG3(DBG_ESP, "ESP before encryption:\n payload = %B\n padding = %B\n "
353 "padding length = %hhu, next header = %hhu", &payload, &padding,
354 (u_int8_t)padding.len, this->next_header);
355
356 /* encrypt the content inline */
357 if (!crypter->encrypt(crypter, ciphertext, iv, NULL))
358 {
359 DBG1(DBG_ESP, "ESP encryption failed");
360 writer->destroy(writer);
361 return FAILED;
362 }
363
364 /* calculate signature */
365 auth_data = writer->get_buf(writer);
366 icv = writer->skip(writer, icv.len);
367 if (!signer->get_signature(signer, auth_data, icv.ptr))
368 {
369 DBG1(DBG_ESP, "ESP encryption failed: signature generation failed");
370 writer->destroy(writer);
371 return FAILED;
372 }
373
374 DBG3(DBG_ESP, "ESP packet:\n SPI %.8x [seq %u]\n IV %B\n "
375 "encrypted %B\n ICV %B", ntohl(spi), next_seqno, &iv,
376 &ciphertext, &icv);
377
378 this->packet->set_data(this->packet, writer->extract_buf(writer));
379 writer->destroy(writer);
380 return SUCCESS;
381 }
382
383 METHOD(esp_packet_t, get_next_header, u_int8_t,
384 private_esp_packet_t *this)
385 {
386 return this->next_header;
387 }
388
389 METHOD(esp_packet_t, get_payload, ip_packet_t*,
390 private_esp_packet_t *this)
391 {
392 return this->payload;
393 }
394
395 METHOD(esp_packet_t, extract_payload, ip_packet_t*,
396 private_esp_packet_t *this)
397 {
398 ip_packet_t *payload;
399
400 payload = this->payload;
401 this->payload = NULL;
402 return payload;
403 }
404
405 METHOD2(esp_packet_t, packet_t, destroy, void,
406 private_esp_packet_t *this)
407 {
408 DESTROY_IF(this->payload);
409 this->packet->destroy(this->packet);
410 free(this);
411 }
412
413 static private_esp_packet_t *esp_packet_create_internal(packet_t *packet)
414 {
415 private_esp_packet_t *this;
416
417 INIT(this,
418 .public = {
419 .packet = {
420 .set_source = _set_source,
421 .get_source = _get_source,
422 .set_destination = _set_destination,
423 .get_destination = _get_destination,
424 .get_data = _get_data,
425 .set_data = _set_data,
426 .get_dscp = _get_dscp,
427 .set_dscp = _set_dscp,
428 .skip_bytes = _skip_bytes,
429 .clone = _clone,
430 .destroy = _destroy,
431 },
432 .get_source = _get_source,
433 .get_destination = _get_destination,
434 .get_next_header = _get_next_header,
435 .parse_header = _parse_header,
436 .decrypt = _decrypt,
437 .encrypt = _encrypt,
438 .get_payload = _get_payload,
439 .extract_payload = _extract_payload,
440 .destroy = _destroy,
441 },
442 .packet = packet,
443 .next_header = IPPROTO_NONE,
444 );
445 return this;
446 }
447
448 /**
449 * Described in header.
450 */
451 esp_packet_t *esp_packet_create_from_packet(packet_t *packet)
452 {
453 private_esp_packet_t *this;
454
455 this = esp_packet_create_internal(packet);
456
457 return &this->public;
458 }
459
460 /**
461 * Described in header.
462 */
463 esp_packet_t *esp_packet_create_from_payload(host_t *src, host_t *dst,
464 ip_packet_t *payload)
465 {
466 private_esp_packet_t *this;
467 packet_t *packet;
468
469 packet = packet_create_from_data(src, dst, chunk_empty);
470 this = esp_packet_create_internal(packet);
471 this->payload = payload;
472 if (payload)
473 {
474 this->next_header = payload->get_version(payload) == 4 ? IPPROTO_IPIP
475 : IPPROTO_IPV6;
476 }
477 else
478 {
479 this->next_header = IPPROTO_NONE;
480 }
481 return &this->public;
482 }