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