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 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 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 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 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 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 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 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