1 /* $OpenBSD: ip_esp.c,v 1.69 2001/06/26 06:18:59 angelos Exp $ */
2 /*-
3 * The authors of this code are John Ioannidis (ji@tla.org),
4 * Angelos D. Keromytis (kermit@csd.uch.gr) and
5 * Niels Provos (provos@physnet.uni-hamburg.de).
6 *
7 * The original version of this code was written by John Ioannidis
8 * for BSD/OS in Athens, Greece, in November 1995.
9 *
10 * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
11 * by Angelos D. Keromytis.
12 *
13 * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis
14 * and Niels Provos.
15 *
16 * Additional features in 1999 by Angelos D. Keromytis.
17 *
18 * Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis,
19 * Angelos D. Keromytis and Niels Provos.
20 * Copyright (c) 2001 Angelos D. Keromytis.
21 *
22 * Permission to use, copy, and modify this software with or without fee
23 * is hereby granted, provided that this entire notice is included in
24 * all copies of any software which is or includes a copy or
25 * modification of this software.
26 * You may use this code under the GNU public license if you so wish. Please
27 * contribute changes back to the authors under this freer than GPL license
28 * so that we may further the use of strong encryption without limitations to
29 * all.
30 *
31 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
32 * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
33 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
34 * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
35 * PURPOSE.
36 */
37 #include "opt_inet.h"
38 #include "opt_inet6.h"
39 #include "opt_ipsec.h"
40
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/malloc.h>
44 #include <sys/mbuf.h>
45 #include <sys/socket.h>
46 #include <sys/syslog.h>
47 #include <sys/kernel.h>
48 #include <sys/lock.h>
49 #include <sys/random.h>
50 #include <sys/mutex.h>
51 #include <sys/sysctl.h>
52 #include <sys/mutex.h>
53 #include <machine/atomic.h>
54
55 #include <net/if.h>
56 #include <net/vnet.h>
57
58 #include <netinet/in.h>
59 #include <netinet/in_systm.h>
60 #include <netinet/ip.h>
61 #include <netinet/ip_ecn.h>
62 #include <netinet/ip6.h>
63
64 #include <netipsec/ipsec.h>
65 #include <netipsec/ah.h>
66 #include <netipsec/ah_var.h>
67 #include <netipsec/esp.h>
68 #include <netipsec/esp_var.h>
69 #include <netipsec/xform.h>
70
71 #ifdef INET6
72 #include <netinet6/ip6_var.h>
73 #include <netipsec/ipsec6.h>
74 #include <netinet6/ip6_ecn.h>
75 #endif
76
77 #include <netipsec/key.h>
78 #include <netipsec/key_debug.h>
79
80 #include <opencrypto/cryptodev.h>
81 #include <opencrypto/xform.h>
82
83 #define SPI_SIZE 4
84
85 VNET_DEFINE(int, esp_enable) = 1;
86 VNET_DEFINE(int, esp_ctr_compatibility) = 1;
87 VNET_PCPUSTAT_DEFINE(struct espstat, espstat);
88 VNET_PCPUSTAT_SYSINIT(espstat);
89
90 #ifdef VIMAGE
91 VNET_PCPUSTAT_SYSUNINIT(espstat);
92 #endif /* VIMAGE */
93
94 SYSCTL_DECL(_net_inet_esp);
95 SYSCTL_INT(_net_inet_esp, OID_AUTO, esp_enable,
96 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(esp_enable), 0, "");
97 SYSCTL_INT(_net_inet_esp, OID_AUTO, ctr_compatibility,
98 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(esp_ctr_compatibility), 0,
99 "Align AES-CTR encrypted transmitted frames to blocksize");
100 SYSCTL_VNET_PCPUSTAT(_net_inet_esp, IPSECCTL_STATS, stats,
101 struct espstat, espstat,
102 "ESP statistics (struct espstat, netipsec/esp_var.h");
103
104 static MALLOC_DEFINE(M_ESP, "esp", "IPsec ESP");
105
106 static int esp_input_cb(struct cryptop *op);
107 static int esp_output_cb(struct cryptop *crp);
108
109 size_t
esp_hdrsiz(struct secasvar * sav)110 esp_hdrsiz(struct secasvar *sav)
111 {
112 size_t size;
113
114 if (sav != NULL) {
115 /*XXX not right for null algorithm--does it matter??*/
116 IPSEC_ASSERT(sav->tdb_encalgxform != NULL,
117 ("SA with null xform"));
118 if (sav->flags & SADB_X_EXT_OLD)
119 size = sizeof (struct esp);
120 else
121 size = sizeof (struct newesp);
122 size += sav->tdb_encalgxform->blocksize + 9;
123 /*XXX need alg check???*/
124 if (sav->tdb_authalgxform != NULL && sav->replay)
125 size += ah_hdrsiz(sav);
126 } else {
127 /*
128 * base header size
129 * + max iv length for CBC mode
130 * + max pad length
131 * + sizeof (pad length field)
132 * + sizeof (next header field)
133 * + max icv supported.
134 */
135 size = sizeof (struct newesp) + EALG_MAX_BLOCK_LEN + 9 + 16;
136 }
137 return size;
138 }
139
140 /*
141 * esp_init() is called when an SPI is being set up.
142 */
143 static int
esp_init(struct secasvar * sav,struct xformsw * xsp)144 esp_init(struct secasvar *sav, struct xformsw *xsp)
145 {
146 const struct enc_xform *txform;
147 struct crypto_session_params csp;
148 int keylen;
149 int error;
150
151 txform = enc_algorithm_lookup(sav->alg_enc);
152 if (txform == NULL) {
153 DPRINTF(("%s: unsupported encryption algorithm %d\n",
154 __func__, sav->alg_enc));
155 return EINVAL;
156 }
157 if (sav->key_enc == NULL) {
158 DPRINTF(("%s: no encoding key for %s algorithm\n",
159 __func__, txform->name));
160 return EINVAL;
161 }
162 if ((sav->flags & (SADB_X_EXT_OLD | SADB_X_EXT_IV4B)) ==
163 SADB_X_EXT_IV4B) {
164 DPRINTF(("%s: 4-byte IV not supported with protocol\n",
165 __func__));
166 return EINVAL;
167 }
168
169 /* subtract off the salt, RFC4106, 8.1 and RFC3686, 5.1 */
170 keylen = _KEYLEN(sav->key_enc) - SAV_ISCTRORGCM(sav) * 4 -
171 SAV_ISCHACHA(sav) * 4;
172 if (txform->minkey > keylen || keylen > txform->maxkey) {
173 DPRINTF(("%s: invalid key length %u, must be in the range "
174 "[%u..%u] for algorithm %s\n", __func__,
175 keylen, txform->minkey, txform->maxkey,
176 txform->name));
177 return EINVAL;
178 }
179
180 if (SAV_ISCTRORGCM(sav) || SAV_ISCHACHA(sav))
181 sav->ivlen = 8; /* RFC4106 3.1 and RFC3686 3.1 */
182 else
183 sav->ivlen = txform->ivsize;
184
185 memset(&csp, 0, sizeof(csp));
186
187 /*
188 * Setup AH-related state.
189 */
190 if (sav->alg_auth != 0) {
191 error = ah_init0(sav, xsp, &csp);
192 if (error)
193 return error;
194 }
195
196 /* NB: override anything set in ah_init0 */
197 sav->tdb_xform = xsp;
198 sav->tdb_encalgxform = txform;
199
200 /*
201 * Whenever AES-GCM is used for encryption, one
202 * of the AES authentication algorithms is chosen
203 * as well, based on the key size.
204 */
205 if (sav->alg_enc == SADB_X_EALG_AESGCM16) {
206 switch (keylen) {
207 case AES_128_GMAC_KEY_LEN:
208 sav->alg_auth = SADB_X_AALG_AES128GMAC;
209 sav->tdb_authalgxform = &auth_hash_nist_gmac_aes_128;
210 break;
211 case AES_192_GMAC_KEY_LEN:
212 sav->alg_auth = SADB_X_AALG_AES192GMAC;
213 sav->tdb_authalgxform = &auth_hash_nist_gmac_aes_192;
214 break;
215 case AES_256_GMAC_KEY_LEN:
216 sav->alg_auth = SADB_X_AALG_AES256GMAC;
217 sav->tdb_authalgxform = &auth_hash_nist_gmac_aes_256;
218 break;
219 default:
220 DPRINTF(("%s: invalid key length %u"
221 "for algorithm %s\n", __func__,
222 keylen, txform->name));
223 return EINVAL;
224 }
225 csp.csp_mode = CSP_MODE_AEAD;
226 if (sav->flags & SADB_X_SAFLAGS_ESN)
227 csp.csp_flags |= CSP_F_SEPARATE_AAD;
228 } else if (sav->alg_enc == SADB_X_EALG_CHACHA20POLY1305) {
229 sav->alg_auth = SADB_X_AALG_CHACHA20POLY1305;
230 sav->tdb_authalgxform = &auth_hash_poly1305;
231 csp.csp_mode = CSP_MODE_AEAD;
232 if (sav->flags & SADB_X_SAFLAGS_ESN)
233 csp.csp_flags |= CSP_F_SEPARATE_AAD;
234 } else if (sav->alg_auth != 0) {
235 csp.csp_mode = CSP_MODE_ETA;
236 if (sav->flags & SADB_X_SAFLAGS_ESN)
237 csp.csp_flags |= CSP_F_ESN;
238 } else
239 csp.csp_mode = CSP_MODE_CIPHER;
240
241 /* Initialize crypto session. */
242 csp.csp_cipher_alg = sav->tdb_encalgxform->type;
243 if (csp.csp_cipher_alg != CRYPTO_NULL_CBC) {
244 csp.csp_cipher_key = sav->key_enc->key_data;
245 csp.csp_cipher_klen = _KEYBITS(sav->key_enc) / 8 -
246 SAV_ISCTRORGCM(sav) * 4 - SAV_ISCHACHA(sav) * 4;
247 };
248 csp.csp_ivlen = txform->ivsize;
249
250 error = crypto_newsession(&sav->tdb_cryptoid, &csp, V_crypto_support);
251 return error;
252 }
253
254 static void
esp_cleanup(struct secasvar * sav)255 esp_cleanup(struct secasvar *sav)
256 {
257
258 crypto_freesession(sav->tdb_cryptoid);
259 sav->tdb_cryptoid = NULL;
260 sav->tdb_authalgxform = NULL;
261 sav->tdb_encalgxform = NULL;
262 }
263
264 /*
265 * ESP input processing, called (eventually) through the protocol switch.
266 */
267 static int
esp_input(struct mbuf * m,struct secasvar * sav,int skip,int protoff)268 esp_input(struct mbuf *m, struct secasvar *sav, int skip, int protoff)
269 {
270 IPSEC_DEBUG_DECLARE(char buf[128]);
271 const struct auth_hash *esph;
272 const struct enc_xform *espx;
273 struct xform_data *xd;
274 struct cryptop *crp;
275 struct newesp *esp;
276 uint8_t *ivp;
277 crypto_session_t cryptoid;
278 int alen, error, hlen, plen;
279 uint32_t seqh;
280 const struct crypto_session_params *csp;
281
282 SECASVAR_RLOCK_TRACKER;
283
284 IPSEC_ASSERT(sav != NULL, ("null SA"));
285 IPSEC_ASSERT(sav->tdb_encalgxform != NULL, ("null encoding xform"));
286
287 error = EINVAL;
288 /* Valid IP Packet length ? */
289 if ( (skip&3) || (m->m_pkthdr.len&3) ){
290 DPRINTF(("%s: misaligned packet, skip %u pkt len %u",
291 __func__, skip, m->m_pkthdr.len));
292 ESPSTAT_INC(esps_badilen);
293 goto bad;
294 }
295
296 if (m->m_len < skip + sizeof(*esp)) {
297 m = m_pullup(m, skip + sizeof(*esp));
298 if (m == NULL) {
299 DPRINTF(("%s: cannot pullup header\n", __func__));
300 ESPSTAT_INC(esps_hdrops); /*XXX*/
301 error = ENOBUFS;
302 goto bad;
303 }
304 }
305 esp = (struct newesp *)(mtod(m, caddr_t) + skip);
306
307 esph = sav->tdb_authalgxform;
308 espx = sav->tdb_encalgxform;
309
310 /* Determine the ESP header and auth length */
311 if (sav->flags & SADB_X_EXT_OLD)
312 hlen = sizeof (struct esp) + sav->ivlen;
313 else
314 hlen = sizeof (struct newesp) + sav->ivlen;
315
316 alen = xform_ah_authsize(esph);
317
318 /*
319 * Verify payload length is multiple of encryption algorithm
320 * block size.
321 *
322 * NB: This works for the null algorithm because the blocksize
323 * is 4 and all packets must be 4-byte aligned regardless
324 * of the algorithm.
325 */
326 plen = m->m_pkthdr.len - (skip + hlen + alen);
327 if ((plen & (espx->blocksize - 1)) || (plen <= 0)) {
328 DPRINTF(("%s: payload of %d octets not a multiple of %d octets,"
329 " SA %s/%08lx\n", __func__, plen, espx->blocksize,
330 ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
331 (u_long)ntohl(sav->spi)));
332 ESPSTAT_INC(esps_badilen);
333 goto bad;
334 }
335
336 /*
337 * Check sequence number.
338 */
339 SECASVAR_RLOCK(sav);
340 if (esph != NULL && sav->replay != NULL && sav->replay->wsize != 0) {
341 if (ipsec_chkreplay(ntohl(esp->esp_seq), &seqh, sav) == 0) {
342 SECASVAR_RUNLOCK(sav);
343 DPRINTF(("%s: packet replay check for %s\n", __func__,
344 ipsec_sa2str(sav, buf, sizeof(buf))));
345 ESPSTAT_INC(esps_replay);
346 error = EACCES;
347 goto bad;
348 }
349 seqh = htonl(seqh);
350 }
351 cryptoid = sav->tdb_cryptoid;
352 SECASVAR_RUNLOCK(sav);
353
354 /* Update the counters */
355 ESPSTAT_ADD(esps_ibytes, m->m_pkthdr.len - (skip + hlen + alen));
356
357 /* Get crypto descriptors */
358 crp = crypto_getreq(cryptoid, M_NOWAIT);
359 if (crp == NULL) {
360 DPRINTF(("%s: failed to acquire crypto descriptors\n",
361 __func__));
362 ESPSTAT_INC(esps_crypto);
363 error = ENOBUFS;
364 goto bad;
365 }
366
367 /* Get IPsec-specific opaque pointer */
368 xd = malloc(sizeof(*xd), M_ESP, M_NOWAIT | M_ZERO);
369 if (xd == NULL) {
370 DPRINTF(("%s: failed to allocate xform_data\n", __func__));
371 goto xd_fail;
372 }
373
374 if (esph != NULL) {
375 crp->crp_op = CRYPTO_OP_VERIFY_DIGEST;
376 if (SAV_ISGCM(sav) || SAV_ISCHACHA(sav))
377 crp->crp_aad_length = 8; /* RFC4106 5, SPI + SN */
378 else
379 crp->crp_aad_length = hlen;
380
381 csp = crypto_get_params(crp->crp_session);
382 if ((csp->csp_flags & CSP_F_SEPARATE_AAD) &&
383 (sav->replay != NULL) && (sav->replay->wsize != 0)) {
384 int aad_skip;
385
386 crp->crp_aad_length += sizeof(seqh);
387 crp->crp_aad = malloc(crp->crp_aad_length, M_ESP, M_NOWAIT);
388 if (crp->crp_aad == NULL) {
389 DPRINTF(("%s: failed to allocate xform_data\n",
390 __func__));
391 goto crp_aad_fail;
392 }
393
394 /* SPI */
395 m_copydata(m, skip, SPI_SIZE, crp->crp_aad);
396 aad_skip = SPI_SIZE;
397
398 /* ESN */
399 bcopy(&seqh, (char *)crp->crp_aad + aad_skip, sizeof(seqh));
400 aad_skip += sizeof(seqh);
401
402 /* Rest of aad */
403 if (crp->crp_aad_length - aad_skip > 0)
404 m_copydata(m, skip + SPI_SIZE,
405 crp->crp_aad_length - aad_skip,
406 (char *)crp->crp_aad + aad_skip);
407 } else
408 crp->crp_aad_start = skip;
409
410 if (csp->csp_flags & CSP_F_ESN &&
411 sav->replay != NULL && sav->replay->wsize != 0)
412 memcpy(crp->crp_esn, &seqh, sizeof(seqh));
413
414 crp->crp_digest_start = m->m_pkthdr.len - alen;
415 }
416
417 /* Crypto operation descriptor */
418 crp->crp_flags = CRYPTO_F_CBIFSYNC;
419 crypto_use_mbuf(crp, m);
420 crp->crp_callback = esp_input_cb;
421 crp->crp_opaque = xd;
422
423 /* These are passed as-is to the callback */
424 xd->sav = sav;
425 xd->protoff = protoff;
426 xd->skip = skip;
427 xd->cryptoid = cryptoid;
428 xd->vnet = curvnet;
429
430 /* Decryption descriptor */
431 crp->crp_op |= CRYPTO_OP_DECRYPT;
432 crp->crp_payload_start = skip + hlen;
433 crp->crp_payload_length = m->m_pkthdr.len - (skip + hlen + alen);
434
435 /* Generate or read cipher IV. */
436 if (SAV_ISCTRORGCM(sav) || SAV_ISCHACHA(sav)) {
437 ivp = &crp->crp_iv[0];
438
439 /*
440 * AES-GCM and AES-CTR use similar cipher IV formats
441 * defined in RFC 4106 section 4 and RFC 3686 section
442 * 4, respectively.
443 *
444 * The first 4 bytes of the cipher IV contain an
445 * implicit salt, or nonce, obtained from the last 4
446 * bytes of the encryption key. The next 8 bytes hold
447 * an explicit IV unique to each packet. This
448 * explicit IV is used as the ESP IV for the packet.
449 * The last 4 bytes hold a big-endian block counter
450 * incremented for each block. For AES-GCM, the block
451 * counter's initial value is defined as part of the
452 * algorithm. For AES-CTR, the block counter's
453 * initial value for each packet is defined as 1 by
454 * RFC 3686.
455 *
456 * ------------------------------------------
457 * | Salt | Explicit ESP IV | Block Counter |
458 * ------------------------------------------
459 * 4 bytes 8 bytes 4 bytes
460 */
461 memcpy(ivp, sav->key_enc->key_data +
462 _KEYLEN(sav->key_enc) - 4, 4);
463 m_copydata(m, skip + hlen - sav->ivlen, sav->ivlen, &ivp[4]);
464 if (SAV_ISCTR(sav)) {
465 be32enc(&ivp[sav->ivlen + 4], 1);
466 }
467 crp->crp_flags |= CRYPTO_F_IV_SEPARATE;
468 } else if (sav->ivlen != 0)
469 crp->crp_iv_start = skip + hlen - sav->ivlen;
470
471 if (V_async_crypto)
472 return (crypto_dispatch_async(crp, CRYPTO_ASYNC_ORDERED));
473 else
474 return (crypto_dispatch(crp));
475
476 crp_aad_fail:
477 free(xd, M_ESP);
478 xd_fail:
479 crypto_freereq(crp);
480 ESPSTAT_INC(esps_crypto);
481 error = ENOBUFS;
482 bad:
483 m_freem(m);
484 key_freesav(&sav);
485 return (error);
486 }
487
488 /*
489 * ESP input callback from the crypto driver.
490 */
491 static int
esp_input_cb(struct cryptop * crp)492 esp_input_cb(struct cryptop *crp)
493 {
494 IPSEC_DEBUG_DECLARE(char buf[128]);
495 uint8_t lastthree[3];
496 const struct auth_hash *esph;
497 struct mbuf *m;
498 struct xform_data *xd;
499 struct secasvar *sav;
500 struct secasindex *saidx;
501 crypto_session_t cryptoid;
502 int hlen, skip, protoff, error, alen;
503
504 SECASVAR_RLOCK_TRACKER;
505
506 m = crp->crp_buf.cb_mbuf;
507 xd = crp->crp_opaque;
508 CURVNET_SET(xd->vnet);
509 sav = xd->sav;
510 if (sav->state >= SADB_SASTATE_DEAD) {
511 /* saidx is freed */
512 DPRINTF(("%s: dead SA %p spi %#x\n", __func__, sav, sav->spi));
513 ESPSTAT_INC(esps_notdb);
514 error = ESRCH;
515 goto bad;
516 }
517 skip = xd->skip;
518 protoff = xd->protoff;
519 cryptoid = xd->cryptoid;
520 saidx = &sav->sah->saidx;
521 esph = sav->tdb_authalgxform;
522
523 /* Check for crypto errors */
524 if (crp->crp_etype) {
525 if (crp->crp_etype == EAGAIN) {
526 /* Reset the session ID */
527 if (ipsec_updateid(sav, &crp->crp_session, &cryptoid) != 0)
528 crypto_freesession(cryptoid);
529 xd->cryptoid = crp->crp_session;
530 CURVNET_RESTORE();
531 return (crypto_dispatch(crp));
532 }
533
534 /* EBADMSG indicates authentication failure. */
535 if (!(crp->crp_etype == EBADMSG && esph != NULL)) {
536 ESPSTAT_INC(esps_noxform);
537 DPRINTF(("%s: crypto error %d\n", __func__,
538 crp->crp_etype));
539 error = crp->crp_etype;
540 goto bad;
541 }
542 }
543
544 /* Shouldn't happen... */
545 if (m == NULL) {
546 ESPSTAT_INC(esps_crypto);
547 DPRINTF(("%s: bogus returned buffer from crypto\n", __func__));
548 error = EINVAL;
549 goto bad;
550 }
551 ESPSTAT_INC2(esps_hist, sav->alg_enc);
552
553 /* If authentication was performed, check now. */
554 if (esph != NULL) {
555 alen = xform_ah_authsize(esph);
556 AHSTAT_INC2(ahs_hist, sav->alg_auth);
557 if (crp->crp_etype == EBADMSG) {
558 DPRINTF(("%s: authentication hash mismatch for "
559 "packet in SA %s/%08lx\n", __func__,
560 ipsec_address(&saidx->dst, buf, sizeof(buf)),
561 (u_long) ntohl(sav->spi)));
562 ESPSTAT_INC(esps_badauth);
563 error = EACCES;
564 goto bad;
565 }
566 m->m_flags |= M_AUTHIPDGM;
567 /* Remove trailing authenticator */
568 m_adj(m, -alen);
569 }
570
571 /* Release the crypto descriptors */
572 free(xd, M_ESP), xd = NULL;
573 free(crp->crp_aad, M_ESP), crp->crp_aad = NULL;
574 crypto_freereq(crp), crp = NULL;
575
576 /*
577 * Packet is now decrypted.
578 */
579 m->m_flags |= M_DECRYPTED;
580
581 /*
582 * Update replay sequence number, if appropriate.
583 */
584 if (sav->replay) {
585 u_int32_t seq;
586
587 m_copydata(m, skip + offsetof(struct newesp, esp_seq),
588 sizeof (seq), (caddr_t) &seq);
589 SECASVAR_RLOCK(sav);
590 if (ipsec_updatereplay(ntohl(seq), sav)) {
591 SECASVAR_RUNLOCK(sav);
592 DPRINTF(("%s: packet replay check for %s\n", __func__,
593 ipsec_sa2str(sav, buf, sizeof(buf))));
594 ESPSTAT_INC(esps_replay);
595 error = EACCES;
596 goto bad;
597 }
598 SECASVAR_RUNLOCK(sav);
599 }
600
601 /* Determine the ESP header length */
602 if (sav->flags & SADB_X_EXT_OLD)
603 hlen = sizeof (struct esp) + sav->ivlen;
604 else
605 hlen = sizeof (struct newesp) + sav->ivlen;
606
607 /* Remove the ESP header and IV from the mbuf. */
608 error = m_striphdr(m, skip, hlen);
609 if (error) {
610 ESPSTAT_INC(esps_hdrops);
611 DPRINTF(("%s: bad mbuf chain, SA %s/%08lx\n", __func__,
612 ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
613 (u_long) ntohl(sav->spi)));
614 goto bad;
615 }
616
617 /* Save the last three bytes of decrypted data */
618 m_copydata(m, m->m_pkthdr.len - 3, 3, lastthree);
619
620 /* Verify pad length */
621 if (lastthree[1] + 2 > m->m_pkthdr.len - skip) {
622 ESPSTAT_INC(esps_badilen);
623 DPRINTF(("%s: invalid padding length %d for %u byte packet "
624 "in SA %s/%08lx\n", __func__, lastthree[1],
625 m->m_pkthdr.len - skip,
626 ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
627 (u_long) ntohl(sav->spi)));
628 error = EINVAL;
629 goto bad;
630 }
631
632 /* Verify correct decryption by checking the last padding bytes */
633 if ((sav->flags & SADB_X_EXT_PMASK) != SADB_X_EXT_PRAND) {
634 if (lastthree[1] != lastthree[0] && lastthree[1] != 0) {
635 ESPSTAT_INC(esps_badenc);
636 DPRINTF(("%s: decryption failed for packet in "
637 "SA %s/%08lx\n", __func__, ipsec_address(
638 &sav->sah->saidx.dst, buf, sizeof(buf)),
639 (u_long) ntohl(sav->spi)));
640 error = EINVAL;
641 goto bad;
642 }
643 }
644
645 /*
646 * RFC4303 2.6:
647 * Silently drop packet if next header field is IPPROTO_NONE.
648 */
649 if (lastthree[2] == IPPROTO_NONE)
650 goto bad;
651
652 /* Trim the mbuf chain to remove trailing authenticator and padding */
653 m_adj(m, -(lastthree[1] + 2));
654
655 /* Restore the Next Protocol field */
656 m_copyback(m, protoff, sizeof (u_int8_t), lastthree + 2);
657
658 switch (saidx->dst.sa.sa_family) {
659 #ifdef INET6
660 case AF_INET6:
661 error = ipsec6_common_input_cb(m, sav, skip, protoff);
662 break;
663 #endif
664 #ifdef INET
665 case AF_INET:
666 error = ipsec4_common_input_cb(m, sav, skip, protoff);
667 break;
668 #endif
669 default:
670 panic("%s: Unexpected address family: %d saidx=%p", __func__,
671 saidx->dst.sa.sa_family, saidx);
672 }
673 CURVNET_RESTORE();
674 return error;
675 bad:
676 if (sav != NULL)
677 key_freesav(&sav);
678 if (m != NULL)
679 m_freem(m);
680 if (xd != NULL)
681 free(xd, M_ESP);
682 if (crp != NULL) {
683 free(crp->crp_aad, M_ESP);
684 crypto_freereq(crp);
685 }
686 CURVNET_RESTORE();
687 return error;
688 }
689 /*
690 * ESP output routine, called by ipsec[46]_perform_request().
691 */
692 static int
esp_output(struct mbuf * m,struct secpolicy * sp,struct secasvar * sav,u_int idx,int skip,int protoff)693 esp_output(struct mbuf *m, struct secpolicy *sp, struct secasvar *sav,
694 u_int idx, int skip, int protoff)
695 {
696 IPSEC_DEBUG_DECLARE(char buf[IPSEC_ADDRSTRLEN]);
697 struct cryptop *crp;
698 const struct auth_hash *esph;
699 const struct enc_xform *espx;
700 struct mbuf *mo = NULL;
701 struct xform_data *xd;
702 struct secasindex *saidx;
703 unsigned char *pad;
704 uint8_t *ivp;
705 uint64_t cntr;
706 crypto_session_t cryptoid;
707 int hlen, rlen, padding, blks, alen, i, roff;
708 int error, maxpacketsize;
709 uint8_t prot;
710 uint32_t seqh;
711 const struct crypto_session_params *csp;
712
713 SECASVAR_RLOCK_TRACKER;
714
715 IPSEC_ASSERT(sav != NULL, ("null SA"));
716 esph = sav->tdb_authalgxform;
717 espx = sav->tdb_encalgxform;
718 IPSEC_ASSERT(espx != NULL, ("null encoding xform"));
719
720 if (sav->flags & SADB_X_EXT_OLD)
721 hlen = sizeof (struct esp) + sav->ivlen;
722 else
723 hlen = sizeof (struct newesp) + sav->ivlen;
724
725 rlen = m->m_pkthdr.len - skip; /* Raw payload length. */
726 /*
727 * RFC4303 2.4 Requires 4 byte alignment.
728 * Old versions of FreeBSD can't decrypt partial blocks encrypted
729 * with AES-CTR. Align payload to native_blocksize (16 bytes)
730 * in order to preserve compatibility.
731 */
732 if (SAV_ISCTR(sav) && V_esp_ctr_compatibility)
733 blks = MAX(4, espx->native_blocksize); /* Cipher blocksize */
734 else
735 blks = MAX(4, espx->blocksize);
736
737 /* XXX clamp padding length a la KAME??? */
738 padding = ((blks - ((rlen + 2) % blks)) % blks) + 2;
739
740 alen = xform_ah_authsize(esph);
741
742 ESPSTAT_INC(esps_output);
743
744 saidx = &sav->sah->saidx;
745 /* Check for maximum packet size violations. */
746 switch (saidx->dst.sa.sa_family) {
747 #ifdef INET
748 case AF_INET:
749 maxpacketsize = IP_MAXPACKET;
750 break;
751 #endif /* INET */
752 #ifdef INET6
753 case AF_INET6:
754 maxpacketsize = IPV6_MAXPACKET;
755 break;
756 #endif /* INET6 */
757 default:
758 DPRINTF(("%s: unknown/unsupported protocol "
759 "family %d, SA %s/%08lx\n", __func__,
760 saidx->dst.sa.sa_family, ipsec_address(&saidx->dst,
761 buf, sizeof(buf)), (u_long) ntohl(sav->spi)));
762 ESPSTAT_INC(esps_nopf);
763 error = EPFNOSUPPORT;
764 goto bad;
765 }
766 /*
767 DPRINTF(("%s: skip %d hlen %d rlen %d padding %d alen %d blksd %d\n",
768 __func__, skip, hlen, rlen, padding, alen, blks)); */
769 if (skip + hlen + rlen + padding + alen > maxpacketsize) {
770 DPRINTF(("%s: packet in SA %s/%08lx got too big "
771 "(len %u, max len %u)\n", __func__,
772 ipsec_address(&saidx->dst, buf, sizeof(buf)),
773 (u_long) ntohl(sav->spi),
774 skip + hlen + rlen + padding + alen, maxpacketsize));
775 ESPSTAT_INC(esps_toobig);
776 error = EMSGSIZE;
777 goto bad;
778 }
779
780 /* Update the counters. */
781 ESPSTAT_ADD(esps_obytes, m->m_pkthdr.len - skip);
782
783 m = m_unshare(m, M_NOWAIT);
784 if (m == NULL) {
785 DPRINTF(("%s: cannot clone mbuf chain, SA %s/%08lx\n", __func__,
786 ipsec_address(&saidx->dst, buf, sizeof(buf)),
787 (u_long) ntohl(sav->spi)));
788 ESPSTAT_INC(esps_hdrops);
789 error = ENOBUFS;
790 goto bad;
791 }
792
793 /* Inject ESP header. */
794 mo = m_makespace(m, skip, hlen, &roff);
795 if (mo == NULL) {
796 DPRINTF(("%s: %u byte ESP hdr inject failed for SA %s/%08lx\n",
797 __func__, hlen, ipsec_address(&saidx->dst, buf,
798 sizeof(buf)), (u_long) ntohl(sav->spi)));
799 ESPSTAT_INC(esps_hdrops); /* XXX diffs from openbsd */
800 error = ENOBUFS;
801 goto bad;
802 }
803
804 /* Initialize ESP header. */
805 bcopy((caddr_t) &sav->spi, mtod(mo, caddr_t) + roff,
806 sizeof(uint32_t));
807 SECASVAR_RLOCK(sav);
808 if (sav->replay) {
809 uint32_t replay;
810
811 SECREPLAY_LOCK(sav->replay);
812 #ifdef REGRESSION
813 /* Emulate replay attack when ipsec_replay is TRUE. */
814 if (!V_ipsec_replay)
815 #endif
816 sav->replay->count++;
817 replay = htonl((uint32_t)sav->replay->count);
818
819 bcopy((caddr_t) &replay, mtod(mo, caddr_t) + roff +
820 sizeof(uint32_t), sizeof(uint32_t));
821
822 seqh = htonl((uint32_t)(sav->replay->count >> IPSEC_SEQH_SHIFT));
823 SECREPLAY_UNLOCK(sav->replay);
824 }
825 cryptoid = sav->tdb_cryptoid;
826 if (SAV_ISCTRORGCM(sav) || SAV_ISCHACHA(sav))
827 cntr = sav->cntr++;
828 SECASVAR_RUNLOCK(sav);
829
830 /*
831 * Add padding -- better to do it ourselves than use the crypto engine,
832 * although if/when we support compression, we'd have to do that.
833 */
834 pad = (u_char *) m_pad(m, padding + alen);
835 if (pad == NULL) {
836 DPRINTF(("%s: m_pad failed for SA %s/%08lx\n", __func__,
837 ipsec_address(&saidx->dst, buf, sizeof(buf)),
838 (u_long) ntohl(sav->spi)));
839 m = NULL; /* NB: free'd by m_pad */
840 error = ENOBUFS;
841 goto bad;
842 }
843
844 /*
845 * Add padding: random, zero, or self-describing.
846 * XXX catch unexpected setting
847 */
848 switch (sav->flags & SADB_X_EXT_PMASK) {
849 case SADB_X_EXT_PRAND:
850 arc4random_buf(pad, padding - 2);
851 break;
852 case SADB_X_EXT_PZERO:
853 bzero(pad, padding - 2);
854 break;
855 case SADB_X_EXT_PSEQ:
856 for (i = 0; i < padding - 2; i++)
857 pad[i] = i+1;
858 break;
859 }
860
861 /* Fix padding length and Next Protocol in padding itself. */
862 pad[padding - 2] = padding - 2;
863 m_copydata(m, protoff, sizeof(u_int8_t), pad + padding - 1);
864
865 /* Fix Next Protocol in IPv4/IPv6 header. */
866 prot = IPPROTO_ESP;
867 m_copyback(m, protoff, sizeof(u_int8_t), (u_char *) &prot);
868
869 /* Get crypto descriptor. */
870 crp = crypto_getreq(cryptoid, M_NOWAIT);
871 if (crp == NULL) {
872 DPRINTF(("%s: failed to acquire crypto descriptor\n",
873 __func__));
874 ESPSTAT_INC(esps_crypto);
875 error = ENOBUFS;
876 goto bad;
877 }
878
879 /* IPsec-specific opaque crypto info. */
880 xd = malloc(sizeof(struct xform_data), M_ESP, M_NOWAIT | M_ZERO);
881 if (xd == NULL) {
882 DPRINTF(("%s: failed to allocate xform_data\n", __func__));
883 goto xd_fail;
884 }
885
886 /* Encryption descriptor. */
887 crp->crp_payload_start = skip + hlen;
888 crp->crp_payload_length = m->m_pkthdr.len - (skip + hlen + alen);
889 crp->crp_op = CRYPTO_OP_ENCRYPT;
890
891 /* Generate cipher and ESP IVs. */
892 ivp = &crp->crp_iv[0];
893 if (SAV_ISCTRORGCM(sav) || SAV_ISCHACHA(sav)) {
894 /*
895 * See comment in esp_input() for details on the
896 * cipher IV. A simple per-SA counter stored in
897 * 'cntr' is used as the explicit ESP IV.
898 */
899 memcpy(ivp, sav->key_enc->key_data +
900 _KEYLEN(sav->key_enc) - 4, 4);
901 be64enc(&ivp[4], cntr);
902 if (SAV_ISCTR(sav)) {
903 be32enc(&ivp[sav->ivlen + 4], 1);
904 }
905 m_copyback(m, skip + hlen - sav->ivlen, sav->ivlen, &ivp[4]);
906 crp->crp_flags |= CRYPTO_F_IV_SEPARATE;
907 } else if (sav->ivlen != 0) {
908 arc4rand(ivp, sav->ivlen, 0);
909 crp->crp_iv_start = skip + hlen - sav->ivlen;
910 m_copyback(m, crp->crp_iv_start, sav->ivlen, ivp);
911 }
912
913 /* Callback parameters */
914 xd->sp = sp;
915 xd->sav = sav;
916 xd->idx = idx;
917 xd->cryptoid = cryptoid;
918 xd->vnet = curvnet;
919
920 /* Crypto operation descriptor. */
921 crp->crp_flags |= CRYPTO_F_CBIFSYNC;
922 crypto_use_mbuf(crp, m);
923 crp->crp_callback = esp_output_cb;
924 crp->crp_opaque = xd;
925
926 if (esph) {
927 /* Authentication descriptor. */
928 crp->crp_op |= CRYPTO_OP_COMPUTE_DIGEST;
929 if (SAV_ISGCM(sav) || SAV_ISCHACHA(sav))
930 crp->crp_aad_length = 8; /* RFC4106 5, SPI + SN */
931 else
932 crp->crp_aad_length = hlen;
933
934 csp = crypto_get_params(crp->crp_session);
935 if (csp->csp_flags & CSP_F_SEPARATE_AAD &&
936 sav->replay != NULL) {
937 int aad_skip;
938
939 crp->crp_aad_length += sizeof(seqh);
940 crp->crp_aad = malloc(crp->crp_aad_length, M_ESP, M_NOWAIT);
941 if (crp->crp_aad == NULL) {
942 DPRINTF(("%s: failed to allocate xform_data\n",
943 __func__));
944 goto crp_aad_fail;
945 }
946
947 /* SPI */
948 m_copydata(m, skip, SPI_SIZE, crp->crp_aad);
949 aad_skip = SPI_SIZE;
950
951 /* ESN */
952 bcopy(&seqh, (char *)crp->crp_aad + aad_skip, sizeof(seqh));
953 aad_skip += sizeof(seqh);
954
955 /* Rest of aad */
956 if (crp->crp_aad_length - aad_skip > 0)
957 m_copydata(m, skip + SPI_SIZE,
958 crp->crp_aad_length - aad_skip,
959 (char *)crp->crp_aad + aad_skip);
960 } else
961 crp->crp_aad_start = skip;
962
963 if (csp->csp_flags & CSP_F_ESN && sav->replay != NULL)
964 memcpy(crp->crp_esn, &seqh, sizeof(seqh));
965
966 crp->crp_digest_start = m->m_pkthdr.len - alen;
967 }
968
969 if (V_async_crypto)
970 return (crypto_dispatch_async(crp, CRYPTO_ASYNC_ORDERED));
971 else
972 return (crypto_dispatch(crp));
973
974 crp_aad_fail:
975 free(xd, M_ESP);
976 xd_fail:
977 crypto_freereq(crp);
978 ESPSTAT_INC(esps_crypto);
979 error = ENOBUFS;
980 bad:
981 if (m)
982 m_freem(m);
983 key_freesav(&sav);
984 key_freesp(&sp);
985 return (error);
986 }
987 /*
988 * ESP output callback from the crypto driver.
989 */
990 static int
esp_output_cb(struct cryptop * crp)991 esp_output_cb(struct cryptop *crp)
992 {
993 struct xform_data *xd;
994 struct secpolicy *sp;
995 struct secasvar *sav;
996 struct mbuf *m;
997 crypto_session_t cryptoid;
998 u_int idx;
999 int error;
1000
1001 xd = (struct xform_data *) crp->crp_opaque;
1002 CURVNET_SET(xd->vnet);
1003 m = crp->crp_buf.cb_mbuf;
1004 sp = xd->sp;
1005 sav = xd->sav;
1006 idx = xd->idx;
1007 cryptoid = xd->cryptoid;
1008
1009 /* Check for crypto errors. */
1010 if (crp->crp_etype) {
1011 if (crp->crp_etype == EAGAIN) {
1012 /* Reset the session ID */
1013 if (ipsec_updateid(sav, &crp->crp_session, &cryptoid) != 0)
1014 crypto_freesession(cryptoid);
1015 xd->cryptoid = crp->crp_session;
1016 CURVNET_RESTORE();
1017 return (crypto_dispatch(crp));
1018 }
1019 ESPSTAT_INC(esps_noxform);
1020 DPRINTF(("%s: crypto error %d\n", __func__, crp->crp_etype));
1021 error = crp->crp_etype;
1022 m_freem(m);
1023 goto bad;
1024 }
1025
1026 /* Shouldn't happen... */
1027 if (m == NULL) {
1028 ESPSTAT_INC(esps_crypto);
1029 DPRINTF(("%s: bogus returned buffer from crypto\n", __func__));
1030 error = EINVAL;
1031 goto bad;
1032 }
1033 free(xd, M_ESP);
1034 free(crp->crp_aad, M_ESP);
1035 crypto_freereq(crp);
1036 ESPSTAT_INC2(esps_hist, sav->alg_enc);
1037 if (sav->tdb_authalgxform != NULL)
1038 AHSTAT_INC2(ahs_hist, sav->alg_auth);
1039
1040 #ifdef REGRESSION
1041 /* Emulate man-in-the-middle attack when ipsec_integrity is TRUE. */
1042 if (V_ipsec_integrity) {
1043 static unsigned char ipseczeroes[AH_HMAC_MAXHASHLEN];
1044 const struct auth_hash *esph;
1045
1046 /*
1047 * Corrupt HMAC if we want to test integrity verification of
1048 * the other side.
1049 */
1050 esph = sav->tdb_authalgxform;
1051 if (esph != NULL) {
1052 int alen;
1053
1054 alen = xform_ah_authsize(esph);
1055 m_copyback(m, m->m_pkthdr.len - alen,
1056 alen, ipseczeroes);
1057 }
1058 }
1059 #endif
1060
1061 /* NB: m is reclaimed by ipsec_process_done. */
1062 error = ipsec_process_done(m, sp, sav, idx);
1063 CURVNET_RESTORE();
1064 return (error);
1065 bad:
1066 free(xd, M_ESP);
1067 free(crp->crp_aad, M_ESP);
1068 crypto_freereq(crp);
1069 key_freesav(&sav);
1070 key_freesp(&sp);
1071 CURVNET_RESTORE();
1072 return (error);
1073 }
1074
1075 static struct xformsw esp_xformsw = {
1076 .xf_type = XF_ESP,
1077 .xf_name = "IPsec ESP",
1078 .xf_init = esp_init,
1079 .xf_cleanup = esp_cleanup,
1080 .xf_input = esp_input,
1081 .xf_output = esp_output,
1082 };
1083
1084 SYSINIT(esp_xform_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE,
1085 xform_attach, &esp_xformsw);
1086 SYSUNINIT(esp_xform_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE,
1087 xform_detach, &esp_xformsw);
1088