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