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