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