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