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(int, esp_ctr_compatibility) = 1; 87 VNET_PCPUSTAT_DEFINE(struct espstat, espstat); 88 VNET_PCPUSTAT_SYSINIT(espstat); 89 90 #ifdef VIMAGE 91 VNET_PCPUSTAT_SYSUNINIT(espstat); 92 #endif /* VIMAGE */ 93 94 SYSCTL_DECL(_net_inet_esp); 95 SYSCTL_INT(_net_inet_esp, OID_AUTO, esp_enable, 96 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(esp_enable), 0, ""); 97 SYSCTL_INT(_net_inet_esp, OID_AUTO, ctr_compatibility, 98 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(esp_ctr_compatibility), 0, 99 "Align AES-CTR encrypted transmitted frames to blocksize"); 100 SYSCTL_VNET_PCPUSTAT(_net_inet_esp, IPSECCTL_STATS, stats, 101 struct espstat, espstat, 102 "ESP statistics (struct espstat, netipsec/esp_var.h"); 103 104 static MALLOC_DEFINE(M_ESP, "esp", "IPsec ESP"); 105 106 static int esp_input_cb(struct cryptop *op); 107 static int esp_output_cb(struct cryptop *crp); 108 109 size_t 110 esp_hdrsiz(struct secasvar *sav) 111 { 112 size_t size; 113 114 if (sav != NULL) { 115 /*XXX not right for null algorithm--does it matter??*/ 116 IPSEC_ASSERT(sav->tdb_encalgxform != NULL, 117 ("SA with null xform")); 118 if (sav->flags & SADB_X_EXT_OLD) 119 size = sizeof (struct esp); 120 else 121 size = sizeof (struct newesp); 122 size += sav->tdb_encalgxform->blocksize + 9; 123 /*XXX need alg check???*/ 124 if (sav->tdb_authalgxform != NULL && sav->replay) 125 size += ah_hdrsiz(sav); 126 } else { 127 /* 128 * base header size 129 * + max iv length for CBC mode 130 * + max pad length 131 * + sizeof (pad length field) 132 * + sizeof (next header field) 133 * + max icv supported. 134 */ 135 size = sizeof (struct newesp) + EALG_MAX_BLOCK_LEN + 9 + 16; 136 } 137 return size; 138 } 139 140 /* 141 * esp_init() is called when an SPI is being set up. 142 */ 143 static int 144 esp_init(struct secasvar *sav, struct xformsw *xsp) 145 { 146 const struct enc_xform *txform; 147 struct crypto_session_params csp; 148 int keylen; 149 int error; 150 151 txform = enc_algorithm_lookup(sav->alg_enc); 152 if (txform == NULL) { 153 DPRINTF(("%s: unsupported encryption algorithm %d\n", 154 __func__, sav->alg_enc)); 155 return EINVAL; 156 } 157 if (sav->key_enc == NULL) { 158 DPRINTF(("%s: no encoding key for %s algorithm\n", 159 __func__, txform->name)); 160 return EINVAL; 161 } 162 if ((sav->flags & (SADB_X_EXT_OLD | SADB_X_EXT_IV4B)) == 163 SADB_X_EXT_IV4B) { 164 DPRINTF(("%s: 4-byte IV not supported with protocol\n", 165 __func__)); 166 return EINVAL; 167 } 168 169 /* subtract off the salt, RFC4106, 8.1 and RFC3686, 5.1 */ 170 keylen = _KEYLEN(sav->key_enc) - SAV_ISCTRORGCM(sav) * 4 - 171 SAV_ISCHACHA(sav) * 4; 172 if (txform->minkey > keylen || keylen > txform->maxkey) { 173 DPRINTF(("%s: invalid key length %u, must be in the range " 174 "[%u..%u] for algorithm %s\n", __func__, 175 keylen, txform->minkey, txform->maxkey, 176 txform->name)); 177 return EINVAL; 178 } 179 180 if (SAV_ISCTRORGCM(sav) || SAV_ISCHACHA(sav)) 181 sav->ivlen = 8; /* RFC4106 3.1 and RFC3686 3.1 */ 182 else 183 sav->ivlen = txform->ivsize; 184 185 memset(&csp, 0, sizeof(csp)); 186 187 /* 188 * Setup AH-related state. 189 */ 190 if (sav->alg_auth != 0) { 191 error = ah_init0(sav, xsp, &csp); 192 if (error) 193 return error; 194 } 195 196 /* NB: override anything set in ah_init0 */ 197 sav->tdb_xform = xsp; 198 sav->tdb_encalgxform = txform; 199 200 /* 201 * Whenever AES-GCM is used for encryption, one 202 * of the AES authentication algorithms is chosen 203 * as well, based on the key size. 204 */ 205 if (sav->alg_enc == SADB_X_EALG_AESGCM16) { 206 switch (keylen) { 207 case AES_128_GMAC_KEY_LEN: 208 sav->alg_auth = SADB_X_AALG_AES128GMAC; 209 sav->tdb_authalgxform = &auth_hash_nist_gmac_aes_128; 210 break; 211 case AES_192_GMAC_KEY_LEN: 212 sav->alg_auth = SADB_X_AALG_AES192GMAC; 213 sav->tdb_authalgxform = &auth_hash_nist_gmac_aes_192; 214 break; 215 case AES_256_GMAC_KEY_LEN: 216 sav->alg_auth = SADB_X_AALG_AES256GMAC; 217 sav->tdb_authalgxform = &auth_hash_nist_gmac_aes_256; 218 break; 219 default: 220 DPRINTF(("%s: invalid key length %u" 221 "for algorithm %s\n", __func__, 222 keylen, txform->name)); 223 return EINVAL; 224 } 225 csp.csp_mode = CSP_MODE_AEAD; 226 if (sav->flags & SADB_X_SAFLAGS_ESN) 227 csp.csp_flags |= CSP_F_SEPARATE_AAD; 228 } else if (sav->alg_enc == SADB_X_EALG_CHACHA20POLY1305) { 229 sav->alg_auth = SADB_X_AALG_CHACHA20POLY1305; 230 sav->tdb_authalgxform = &auth_hash_poly1305; 231 csp.csp_mode = CSP_MODE_AEAD; 232 if (sav->flags & SADB_X_SAFLAGS_ESN) 233 csp.csp_flags |= CSP_F_SEPARATE_AAD; 234 } else if (sav->alg_auth != 0) { 235 csp.csp_mode = CSP_MODE_ETA; 236 if (sav->flags & SADB_X_SAFLAGS_ESN) 237 csp.csp_flags |= CSP_F_ESN; 238 } else 239 csp.csp_mode = CSP_MODE_CIPHER; 240 241 /* Initialize crypto session. */ 242 csp.csp_cipher_alg = sav->tdb_encalgxform->type; 243 if (csp.csp_cipher_alg != CRYPTO_NULL_CBC) { 244 csp.csp_cipher_key = sav->key_enc->key_data; 245 csp.csp_cipher_klen = _KEYBITS(sav->key_enc) / 8 - 246 SAV_ISCTRORGCM(sav) * 4 - SAV_ISCHACHA(sav) * 4; 247 }; 248 csp.csp_ivlen = txform->ivsize; 249 250 error = crypto_newsession(&sav->tdb_cryptoid, &csp, V_crypto_support); 251 return error; 252 } 253 254 static void 255 esp_cleanup(struct secasvar *sav) 256 { 257 258 crypto_freesession(sav->tdb_cryptoid); 259 sav->tdb_cryptoid = NULL; 260 sav->tdb_authalgxform = NULL; 261 sav->tdb_encalgxform = NULL; 262 } 263 264 /* 265 * ESP input processing, called (eventually) through the protocol switch. 266 */ 267 static int 268 esp_input(struct mbuf *m, struct secasvar *sav, int skip, int protoff) 269 { 270 IPSEC_DEBUG_DECLARE(char buf[128]); 271 const struct auth_hash *esph; 272 const struct enc_xform *espx; 273 struct xform_data *xd; 274 struct cryptop *crp; 275 struct newesp *esp; 276 uint8_t *ivp; 277 crypto_session_t cryptoid; 278 int alen, error, hlen, plen; 279 uint32_t seqh; 280 const struct crypto_session_params *csp; 281 282 SECASVAR_RLOCK_TRACKER; 283 284 IPSEC_ASSERT(sav != NULL, ("null SA")); 285 IPSEC_ASSERT(sav->tdb_encalgxform != NULL, ("null encoding xform")); 286 287 error = EINVAL; 288 /* Valid IP Packet length ? */ 289 if ( (skip&3) || (m->m_pkthdr.len&3) ){ 290 DPRINTF(("%s: misaligned packet, skip %u pkt len %u", 291 __func__, skip, m->m_pkthdr.len)); 292 ESPSTAT_INC(esps_badilen); 293 goto bad; 294 } 295 296 if (m->m_len < skip + sizeof(*esp)) { 297 m = m_pullup(m, skip + sizeof(*esp)); 298 if (m == NULL) { 299 DPRINTF(("%s: cannot pullup header\n", __func__)); 300 ESPSTAT_INC(esps_hdrops); /*XXX*/ 301 error = ENOBUFS; 302 goto bad; 303 } 304 } 305 esp = (struct newesp *)(mtod(m, caddr_t) + skip); 306 307 esph = sav->tdb_authalgxform; 308 espx = sav->tdb_encalgxform; 309 310 /* Determine the ESP header and auth length */ 311 if (sav->flags & SADB_X_EXT_OLD) 312 hlen = sizeof (struct esp) + sav->ivlen; 313 else 314 hlen = sizeof (struct newesp) + sav->ivlen; 315 316 alen = xform_ah_authsize(esph); 317 318 /* 319 * Verify payload length is multiple of encryption algorithm 320 * block size. 321 * 322 * NB: This works for the null algorithm because the blocksize 323 * is 4 and all packets must be 4-byte aligned regardless 324 * of the algorithm. 325 */ 326 plen = m->m_pkthdr.len - (skip + hlen + alen); 327 if ((plen & (espx->blocksize - 1)) || (plen <= 0)) { 328 DPRINTF(("%s: payload of %d octets not a multiple of %d octets," 329 " SA %s/%08lx\n", __func__, plen, espx->blocksize, 330 ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)), 331 (u_long)ntohl(sav->spi))); 332 ESPSTAT_INC(esps_badilen); 333 goto bad; 334 } 335 336 /* 337 * Check sequence number. 338 */ 339 SECASVAR_RLOCK(sav); 340 if (esph != NULL && sav->replay != NULL && sav->replay->wsize != 0) { 341 if (ipsec_chkreplay(ntohl(esp->esp_seq), &seqh, sav) == 0) { 342 SECASVAR_RUNLOCK(sav); 343 DPRINTF(("%s: packet replay check for %s\n", __func__, 344 ipsec_sa2str(sav, buf, sizeof(buf)))); 345 ESPSTAT_INC(esps_replay); 346 error = EACCES; 347 goto bad; 348 } 349 seqh = htonl(seqh); 350 } 351 cryptoid = sav->tdb_cryptoid; 352 SECASVAR_RUNLOCK(sav); 353 354 /* Update the counters */ 355 ESPSTAT_ADD(esps_ibytes, m->m_pkthdr.len - (skip + hlen + alen)); 356 357 /* Get crypto descriptors */ 358 crp = crypto_getreq(cryptoid, M_NOWAIT); 359 if (crp == NULL) { 360 DPRINTF(("%s: failed to acquire crypto descriptors\n", 361 __func__)); 362 ESPSTAT_INC(esps_crypto); 363 error = ENOBUFS; 364 goto bad; 365 } 366 367 /* Get IPsec-specific opaque pointer */ 368 xd = malloc(sizeof(*xd), M_ESP, M_NOWAIT | M_ZERO); 369 if (xd == NULL) { 370 DPRINTF(("%s: failed to allocate xform_data\n", __func__)); 371 goto xd_fail; 372 } 373 374 if (esph != NULL) { 375 crp->crp_op = CRYPTO_OP_VERIFY_DIGEST; 376 if (SAV_ISGCM(sav) || SAV_ISCHACHA(sav)) 377 crp->crp_aad_length = 8; /* RFC4106 5, SPI + SN */ 378 else 379 crp->crp_aad_length = hlen; 380 381 csp = crypto_get_params(crp->crp_session); 382 if ((csp->csp_flags & CSP_F_SEPARATE_AAD) && 383 (sav->replay != NULL) && (sav->replay->wsize != 0)) { 384 int aad_skip; 385 386 crp->crp_aad_length += sizeof(seqh); 387 crp->crp_aad = malloc(crp->crp_aad_length, M_ESP, M_NOWAIT); 388 if (crp->crp_aad == NULL) { 389 DPRINTF(("%s: failed to allocate xform_data\n", 390 __func__)); 391 goto crp_aad_fail; 392 } 393 394 /* SPI */ 395 m_copydata(m, skip, SPI_SIZE, crp->crp_aad); 396 aad_skip = SPI_SIZE; 397 398 /* ESN */ 399 bcopy(&seqh, (char *)crp->crp_aad + aad_skip, sizeof(seqh)); 400 aad_skip += sizeof(seqh); 401 402 /* Rest of aad */ 403 if (crp->crp_aad_length - aad_skip > 0) 404 m_copydata(m, skip + SPI_SIZE, 405 crp->crp_aad_length - aad_skip, 406 (char *)crp->crp_aad + aad_skip); 407 } else 408 crp->crp_aad_start = skip; 409 410 if (csp->csp_flags & CSP_F_ESN && 411 sav->replay != NULL && sav->replay->wsize != 0) 412 memcpy(crp->crp_esn, &seqh, sizeof(seqh)); 413 414 crp->crp_digest_start = m->m_pkthdr.len - alen; 415 } 416 417 /* Crypto operation descriptor */ 418 crp->crp_flags = CRYPTO_F_CBIFSYNC; 419 crypto_use_mbuf(crp, m); 420 crp->crp_callback = esp_input_cb; 421 crp->crp_opaque = xd; 422 423 /* These are passed as-is to the callback */ 424 xd->sav = sav; 425 xd->protoff = protoff; 426 xd->skip = skip; 427 xd->cryptoid = cryptoid; 428 xd->vnet = curvnet; 429 430 /* Decryption descriptor */ 431 crp->crp_op |= CRYPTO_OP_DECRYPT; 432 crp->crp_payload_start = skip + hlen; 433 crp->crp_payload_length = m->m_pkthdr.len - (skip + hlen + alen); 434 435 /* Generate or read cipher IV. */ 436 if (SAV_ISCTRORGCM(sav) || SAV_ISCHACHA(sav)) { 437 ivp = &crp->crp_iv[0]; 438 439 /* 440 * AES-GCM and AES-CTR use similar cipher IV formats 441 * defined in RFC 4106 section 4 and RFC 3686 section 442 * 4, respectively. 443 * 444 * The first 4 bytes of the cipher IV contain an 445 * implicit salt, or nonce, obtained from the last 4 446 * bytes of the encryption key. The next 8 bytes hold 447 * an explicit IV unique to each packet. This 448 * explicit IV is used as the ESP IV for the packet. 449 * The last 4 bytes hold a big-endian block counter 450 * incremented for each block. For AES-GCM, the block 451 * counter's initial value is defined as part of the 452 * algorithm. For AES-CTR, the block counter's 453 * initial value for each packet is defined as 1 by 454 * RFC 3686. 455 * 456 * ------------------------------------------ 457 * | Salt | Explicit ESP IV | Block Counter | 458 * ------------------------------------------ 459 * 4 bytes 8 bytes 4 bytes 460 */ 461 memcpy(ivp, sav->key_enc->key_data + 462 _KEYLEN(sav->key_enc) - 4, 4); 463 m_copydata(m, skip + hlen - sav->ivlen, sav->ivlen, &ivp[4]); 464 if (SAV_ISCTR(sav)) { 465 be32enc(&ivp[sav->ivlen + 4], 1); 466 } 467 crp->crp_flags |= CRYPTO_F_IV_SEPARATE; 468 } else if (sav->ivlen != 0) 469 crp->crp_iv_start = skip + hlen - sav->ivlen; 470 471 if (V_async_crypto) 472 return (crypto_dispatch_async(crp, CRYPTO_ASYNC_ORDERED)); 473 else 474 return (crypto_dispatch(crp)); 475 476 crp_aad_fail: 477 free(xd, M_ESP); 478 xd_fail: 479 crypto_freereq(crp); 480 ESPSTAT_INC(esps_crypto); 481 error = ENOBUFS; 482 bad: 483 m_freem(m); 484 key_freesav(&sav); 485 return (error); 486 } 487 488 /* 489 * ESP input callback from the crypto driver. 490 */ 491 static int 492 esp_input_cb(struct cryptop *crp) 493 { 494 IPSEC_DEBUG_DECLARE(char buf[128]); 495 struct rm_priotracker sahtree_tracker; 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 ipsec_sahtree_rlock(&sahtree_tracker); 512 if (sav->state >= SADB_SASTATE_DEAD) { 513 /* saidx is freed */ 514 DPRINTF(("%s: dead SA %p spi %#x\n", __func__, sav, sav->spi)); 515 ESPSTAT_INC(esps_notdb); 516 error = ESRCH; 517 goto bad; 518 } 519 skip = xd->skip; 520 protoff = xd->protoff; 521 cryptoid = xd->cryptoid; 522 saidx = &sav->sah->saidx; 523 esph = sav->tdb_authalgxform; 524 525 /* Check for crypto errors */ 526 if (crp->crp_etype) { 527 if (crp->crp_etype == EAGAIN) { 528 /* Reset the session ID */ 529 if (ipsec_updateid(sav, &crp->crp_session, &cryptoid) != 0) 530 crypto_freesession(cryptoid); 531 xd->cryptoid = crp->crp_session; 532 ipsec_sahtree_runlock(&sahtree_tracker); 533 CURVNET_RESTORE(); 534 return (crypto_dispatch(crp)); 535 } 536 537 /* EBADMSG indicates authentication failure. */ 538 if (!(crp->crp_etype == EBADMSG && esph != NULL)) { 539 ESPSTAT_INC(esps_noxform); 540 DPRINTF(("%s: crypto error %d\n", __func__, 541 crp->crp_etype)); 542 error = crp->crp_etype; 543 goto bad; 544 } 545 } 546 547 /* Shouldn't happen... */ 548 if (m == NULL) { 549 ESPSTAT_INC(esps_crypto); 550 DPRINTF(("%s: bogus returned buffer from crypto\n", __func__)); 551 error = EINVAL; 552 goto bad; 553 } 554 ESPSTAT_INC2(esps_hist, sav->alg_enc); 555 556 /* If authentication was performed, check now. */ 557 if (esph != NULL) { 558 alen = xform_ah_authsize(esph); 559 AHSTAT_INC2(ahs_hist, sav->alg_auth); 560 if (crp->crp_etype == EBADMSG) { 561 DPRINTF(("%s: authentication hash mismatch for " 562 "packet in SA %s/%08lx\n", __func__, 563 ipsec_address(&saidx->dst, buf, sizeof(buf)), 564 (u_long) ntohl(sav->spi))); 565 ESPSTAT_INC(esps_badauth); 566 error = EACCES; 567 goto bad; 568 } 569 m->m_flags |= M_AUTHIPDGM; 570 /* Remove trailing authenticator */ 571 m_adj(m, -alen); 572 } 573 574 /* Release the crypto descriptors */ 575 free(xd, M_ESP), xd = NULL; 576 free(crp->crp_aad, M_ESP), crp->crp_aad = NULL; 577 crypto_freereq(crp), crp = NULL; 578 579 /* 580 * Packet is now decrypted. 581 */ 582 m->m_flags |= M_DECRYPTED; 583 584 /* 585 * Update replay sequence number, if appropriate. 586 */ 587 if (sav->replay) { 588 u_int32_t seq; 589 590 m_copydata(m, skip + offsetof(struct newesp, esp_seq), 591 sizeof (seq), (caddr_t) &seq); 592 SECASVAR_RLOCK(sav); 593 if (ipsec_updatereplay(ntohl(seq), sav)) { 594 SECASVAR_RUNLOCK(sav); 595 DPRINTF(("%s: packet replay check for %s\n", __func__, 596 ipsec_sa2str(sav, buf, sizeof(buf)))); 597 ESPSTAT_INC(esps_replay); 598 error = EACCES; 599 goto bad; 600 } 601 SECASVAR_RUNLOCK(sav); 602 } 603 604 /* Determine the ESP header length */ 605 if (sav->flags & SADB_X_EXT_OLD) 606 hlen = sizeof (struct esp) + sav->ivlen; 607 else 608 hlen = sizeof (struct newesp) + sav->ivlen; 609 610 /* Remove the ESP header and IV from the mbuf. */ 611 error = m_striphdr(m, skip, hlen); 612 if (error) { 613 ESPSTAT_INC(esps_hdrops); 614 DPRINTF(("%s: bad mbuf chain, SA %s/%08lx\n", __func__, 615 ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)), 616 (u_long) ntohl(sav->spi))); 617 goto bad; 618 } 619 620 /* Save the last three bytes of decrypted data */ 621 m_copydata(m, m->m_pkthdr.len - 3, 3, lastthree); 622 623 /* Verify pad length */ 624 if (lastthree[1] + 2 > m->m_pkthdr.len - skip) { 625 ESPSTAT_INC(esps_badilen); 626 DPRINTF(("%s: invalid padding length %d for %u byte packet " 627 "in SA %s/%08lx\n", __func__, lastthree[1], 628 m->m_pkthdr.len - skip, 629 ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)), 630 (u_long) ntohl(sav->spi))); 631 error = EINVAL; 632 goto bad; 633 } 634 635 /* Verify correct decryption by checking the last padding bytes */ 636 if ((sav->flags & SADB_X_EXT_PMASK) != SADB_X_EXT_PRAND) { 637 if (lastthree[1] != lastthree[0] && lastthree[1] != 0) { 638 ESPSTAT_INC(esps_badenc); 639 DPRINTF(("%s: decryption failed for packet in " 640 "SA %s/%08lx\n", __func__, ipsec_address( 641 &sav->sah->saidx.dst, buf, sizeof(buf)), 642 (u_long) ntohl(sav->spi))); 643 error = EINVAL; 644 goto bad; 645 } 646 } 647 648 /* 649 * RFC4303 2.6: 650 * Silently drop packet if next header field is IPPROTO_NONE. 651 */ 652 if (lastthree[2] == IPPROTO_NONE) 653 goto bad; 654 655 /* Trim the mbuf chain to remove trailing authenticator and padding */ 656 m_adj(m, -(lastthree[1] + 2)); 657 658 /* Restore the Next Protocol field */ 659 m_copyback(m, protoff, sizeof (u_int8_t), lastthree + 2); 660 661 switch (saidx->dst.sa.sa_family) { 662 #ifdef INET6 663 case AF_INET6: 664 error = ipsec6_common_input_cb(m, sav, skip, protoff, 665 &sahtree_tracker); 666 break; 667 #endif 668 #ifdef INET 669 case AF_INET: 670 error = ipsec4_common_input_cb(m, sav, skip, protoff, 671 &sahtree_tracker); 672 break; 673 #endif 674 default: 675 panic("%s: Unexpected address family: %d saidx=%p", __func__, 676 saidx->dst.sa.sa_family, saidx); 677 } 678 CURVNET_RESTORE(); 679 return error; 680 bad: 681 ipsec_sahtree_runlock(&sahtree_tracker); 682 if (sav != NULL) 683 key_freesav(&sav); 684 if (m != NULL) 685 m_freem(m); 686 if (xd != NULL) 687 free(xd, M_ESP); 688 if (crp != NULL) { 689 free(crp->crp_aad, M_ESP); 690 crypto_freereq(crp); 691 } 692 CURVNET_RESTORE(); 693 return error; 694 } 695 /* 696 * ESP output routine, called by ipsec[46]_perform_request(). 697 */ 698 static int 699 esp_output(struct mbuf *m, struct secpolicy *sp, struct secasvar *sav, 700 u_int idx, int skip, int protoff) 701 { 702 IPSEC_DEBUG_DECLARE(char buf[IPSEC_ADDRSTRLEN]); 703 struct cryptop *crp; 704 const struct auth_hash *esph; 705 const struct enc_xform *espx; 706 struct mbuf *mo = NULL; 707 struct xform_data *xd; 708 struct secasindex *saidx; 709 unsigned char *pad; 710 uint8_t *ivp; 711 uint64_t cntr; 712 crypto_session_t cryptoid; 713 int hlen, rlen, padding, blks, alen, i, roff; 714 int error, maxpacketsize; 715 uint8_t prot; 716 uint32_t seqh; 717 const struct crypto_session_params *csp; 718 719 SECASVAR_RLOCK_TRACKER; 720 721 IPSEC_ASSERT(sav != NULL, ("null SA")); 722 esph = sav->tdb_authalgxform; 723 espx = sav->tdb_encalgxform; 724 IPSEC_ASSERT(espx != NULL, ("null encoding xform")); 725 726 if (sav->flags & SADB_X_EXT_OLD) 727 hlen = sizeof (struct esp) + sav->ivlen; 728 else 729 hlen = sizeof (struct newesp) + sav->ivlen; 730 731 rlen = m->m_pkthdr.len - skip; /* Raw payload length. */ 732 /* 733 * RFC4303 2.4 Requires 4 byte alignment. 734 * Old versions of FreeBSD can't decrypt partial blocks encrypted 735 * with AES-CTR. Align payload to native_blocksize (16 bytes) 736 * in order to preserve compatibility. 737 */ 738 if (SAV_ISCTR(sav) && V_esp_ctr_compatibility) 739 blks = MAX(4, espx->native_blocksize); /* Cipher blocksize */ 740 else 741 blks = MAX(4, espx->blocksize); 742 743 /* XXX clamp padding length a la KAME??? */ 744 padding = ((blks - ((rlen + 2) % blks)) % blks) + 2; 745 746 alen = xform_ah_authsize(esph); 747 748 ESPSTAT_INC(esps_output); 749 750 saidx = &sav->sah->saidx; 751 /* Check for maximum packet size violations. */ 752 switch (saidx->dst.sa.sa_family) { 753 #ifdef INET 754 case AF_INET: 755 maxpacketsize = IP_MAXPACKET; 756 break; 757 #endif /* INET */ 758 #ifdef INET6 759 case AF_INET6: 760 maxpacketsize = IPV6_MAXPACKET; 761 break; 762 #endif /* INET6 */ 763 default: 764 DPRINTF(("%s: unknown/unsupported protocol " 765 "family %d, SA %s/%08lx\n", __func__, 766 saidx->dst.sa.sa_family, ipsec_address(&saidx->dst, 767 buf, sizeof(buf)), (u_long) ntohl(sav->spi))); 768 ESPSTAT_INC(esps_nopf); 769 error = EPFNOSUPPORT; 770 goto bad; 771 } 772 /* 773 DPRINTF(("%s: skip %d hlen %d rlen %d padding %d alen %d blksd %d\n", 774 __func__, skip, hlen, rlen, padding, alen, blks)); */ 775 if (skip + hlen + rlen + padding + alen > maxpacketsize) { 776 DPRINTF(("%s: packet in SA %s/%08lx got too big " 777 "(len %u, max len %u)\n", __func__, 778 ipsec_address(&saidx->dst, buf, sizeof(buf)), 779 (u_long) ntohl(sav->spi), 780 skip + hlen + rlen + padding + alen, maxpacketsize)); 781 ESPSTAT_INC(esps_toobig); 782 error = EMSGSIZE; 783 goto bad; 784 } 785 786 /* Update the counters. */ 787 ESPSTAT_ADD(esps_obytes, m->m_pkthdr.len - skip); 788 789 m = m_unshare(m, M_NOWAIT); 790 if (m == NULL) { 791 DPRINTF(("%s: cannot clone mbuf chain, SA %s/%08lx\n", __func__, 792 ipsec_address(&saidx->dst, buf, sizeof(buf)), 793 (u_long) ntohl(sav->spi))); 794 ESPSTAT_INC(esps_hdrops); 795 error = ENOBUFS; 796 goto bad; 797 } 798 799 /* Inject ESP header. */ 800 mo = m_makespace(m, skip, hlen, &roff); 801 if (mo == NULL) { 802 DPRINTF(("%s: %u byte ESP hdr inject failed for SA %s/%08lx\n", 803 __func__, hlen, ipsec_address(&saidx->dst, buf, 804 sizeof(buf)), (u_long) ntohl(sav->spi))); 805 ESPSTAT_INC(esps_hdrops); /* XXX diffs from openbsd */ 806 error = ENOBUFS; 807 goto bad; 808 } 809 810 /* Initialize ESP header. */ 811 bcopy((caddr_t) &sav->spi, mtod(mo, caddr_t) + roff, 812 sizeof(uint32_t)); 813 SECASVAR_RLOCK(sav); 814 if (sav->replay) { 815 uint32_t replay; 816 817 SECREPLAY_LOCK(sav->replay); 818 #ifdef REGRESSION 819 /* Emulate replay attack when ipsec_replay is TRUE. */ 820 if (!V_ipsec_replay) 821 #endif 822 sav->replay->count++; 823 replay = htonl((uint32_t)sav->replay->count); 824 825 bcopy((caddr_t) &replay, mtod(mo, caddr_t) + roff + 826 sizeof(uint32_t), sizeof(uint32_t)); 827 828 seqh = htonl((uint32_t)(sav->replay->count >> IPSEC_SEQH_SHIFT)); 829 SECREPLAY_UNLOCK(sav->replay); 830 } 831 cryptoid = sav->tdb_cryptoid; 832 if (SAV_ISCTRORGCM(sav) || SAV_ISCHACHA(sav)) 833 cntr = sav->cntr++; 834 SECASVAR_RUNLOCK(sav); 835 836 /* 837 * Add padding -- better to do it ourselves than use the crypto engine, 838 * although if/when we support compression, we'd have to do that. 839 */ 840 pad = (u_char *) m_pad(m, padding + alen); 841 if (pad == NULL) { 842 DPRINTF(("%s: m_pad failed for SA %s/%08lx\n", __func__, 843 ipsec_address(&saidx->dst, buf, sizeof(buf)), 844 (u_long) ntohl(sav->spi))); 845 m = NULL; /* NB: free'd by m_pad */ 846 error = ENOBUFS; 847 goto bad; 848 } 849 850 /* 851 * Add padding: random, zero, or self-describing. 852 * XXX catch unexpected setting 853 */ 854 switch (sav->flags & SADB_X_EXT_PMASK) { 855 case SADB_X_EXT_PRAND: 856 arc4random_buf(pad, padding - 2); 857 break; 858 case SADB_X_EXT_PZERO: 859 bzero(pad, padding - 2); 860 break; 861 case SADB_X_EXT_PSEQ: 862 for (i = 0; i < padding - 2; i++) 863 pad[i] = i+1; 864 break; 865 } 866 867 /* Fix padding length and Next Protocol in padding itself. */ 868 pad[padding - 2] = padding - 2; 869 m_copydata(m, protoff, sizeof(u_int8_t), pad + padding - 1); 870 871 /* Fix Next Protocol in IPv4/IPv6 header. */ 872 prot = IPPROTO_ESP; 873 m_copyback(m, protoff, sizeof(u_int8_t), (u_char *) &prot); 874 875 /* Get crypto descriptor. */ 876 crp = crypto_getreq(cryptoid, M_NOWAIT); 877 if (crp == NULL) { 878 DPRINTF(("%s: failed to acquire crypto descriptor\n", 879 __func__)); 880 ESPSTAT_INC(esps_crypto); 881 error = ENOBUFS; 882 goto bad; 883 } 884 885 /* IPsec-specific opaque crypto info. */ 886 xd = malloc(sizeof(struct xform_data), M_ESP, M_NOWAIT | M_ZERO); 887 if (xd == NULL) { 888 DPRINTF(("%s: failed to allocate xform_data\n", __func__)); 889 goto xd_fail; 890 } 891 892 /* Encryption descriptor. */ 893 crp->crp_payload_start = skip + hlen; 894 crp->crp_payload_length = m->m_pkthdr.len - (skip + hlen + alen); 895 crp->crp_op = CRYPTO_OP_ENCRYPT; 896 897 /* Generate cipher and ESP IVs. */ 898 ivp = &crp->crp_iv[0]; 899 if (SAV_ISCTRORGCM(sav) || SAV_ISCHACHA(sav)) { 900 /* 901 * See comment in esp_input() for details on the 902 * cipher IV. A simple per-SA counter stored in 903 * 'cntr' is used as the explicit ESP IV. 904 */ 905 memcpy(ivp, sav->key_enc->key_data + 906 _KEYLEN(sav->key_enc) - 4, 4); 907 be64enc(&ivp[4], cntr); 908 if (SAV_ISCTR(sav)) { 909 be32enc(&ivp[sav->ivlen + 4], 1); 910 } 911 m_copyback(m, skip + hlen - sav->ivlen, sav->ivlen, &ivp[4]); 912 crp->crp_flags |= CRYPTO_F_IV_SEPARATE; 913 } else if (sav->ivlen != 0) { 914 arc4rand(ivp, sav->ivlen, 0); 915 crp->crp_iv_start = skip + hlen - sav->ivlen; 916 m_copyback(m, crp->crp_iv_start, sav->ivlen, ivp); 917 } 918 919 /* Callback parameters */ 920 xd->sp = sp; 921 xd->sav = sav; 922 xd->idx = idx; 923 xd->cryptoid = cryptoid; 924 xd->vnet = curvnet; 925 926 /* Crypto operation descriptor. */ 927 crp->crp_flags |= CRYPTO_F_CBIFSYNC; 928 crypto_use_mbuf(crp, m); 929 crp->crp_callback = esp_output_cb; 930 crp->crp_opaque = xd; 931 932 if (esph) { 933 /* Authentication descriptor. */ 934 crp->crp_op |= CRYPTO_OP_COMPUTE_DIGEST; 935 if (SAV_ISGCM(sav) || SAV_ISCHACHA(sav)) 936 crp->crp_aad_length = 8; /* RFC4106 5, SPI + SN */ 937 else 938 crp->crp_aad_length = hlen; 939 940 csp = crypto_get_params(crp->crp_session); 941 if (csp->csp_flags & CSP_F_SEPARATE_AAD && 942 sav->replay != NULL) { 943 int aad_skip; 944 945 crp->crp_aad_length += sizeof(seqh); 946 crp->crp_aad = malloc(crp->crp_aad_length, M_ESP, M_NOWAIT); 947 if (crp->crp_aad == NULL) { 948 DPRINTF(("%s: failed to allocate xform_data\n", 949 __func__)); 950 goto crp_aad_fail; 951 } 952 953 /* SPI */ 954 m_copydata(m, skip, SPI_SIZE, crp->crp_aad); 955 aad_skip = SPI_SIZE; 956 957 /* ESN */ 958 bcopy(&seqh, (char *)crp->crp_aad + aad_skip, sizeof(seqh)); 959 aad_skip += sizeof(seqh); 960 961 /* Rest of aad */ 962 if (crp->crp_aad_length - aad_skip > 0) 963 m_copydata(m, skip + SPI_SIZE, 964 crp->crp_aad_length - aad_skip, 965 (char *)crp->crp_aad + aad_skip); 966 } else 967 crp->crp_aad_start = skip; 968 969 if (csp->csp_flags & CSP_F_ESN && sav->replay != NULL) 970 memcpy(crp->crp_esn, &seqh, sizeof(seqh)); 971 972 crp->crp_digest_start = m->m_pkthdr.len - alen; 973 } 974 975 if (V_async_crypto) 976 return (crypto_dispatch_async(crp, CRYPTO_ASYNC_ORDERED)); 977 else 978 return (crypto_dispatch(crp)); 979 980 crp_aad_fail: 981 free(xd, M_ESP); 982 xd_fail: 983 crypto_freereq(crp); 984 ESPSTAT_INC(esps_crypto); 985 error = ENOBUFS; 986 bad: 987 if (m) 988 m_freem(m); 989 key_freesav(&sav); 990 key_freesp(&sp); 991 return (error); 992 } 993 /* 994 * ESP output callback from the crypto driver. 995 */ 996 static int 997 esp_output_cb(struct cryptop *crp) 998 { 999 struct xform_data *xd; 1000 struct secpolicy *sp; 1001 struct secasvar *sav; 1002 struct mbuf *m; 1003 crypto_session_t cryptoid; 1004 u_int idx; 1005 int error; 1006 1007 xd = (struct xform_data *) crp->crp_opaque; 1008 CURVNET_SET(xd->vnet); 1009 m = crp->crp_buf.cb_mbuf; 1010 sp = xd->sp; 1011 sav = xd->sav; 1012 idx = xd->idx; 1013 cryptoid = xd->cryptoid; 1014 1015 /* Check for crypto errors. */ 1016 if (crp->crp_etype) { 1017 if (crp->crp_etype == EAGAIN) { 1018 /* Reset the session ID */ 1019 if (ipsec_updateid(sav, &crp->crp_session, &cryptoid) != 0) 1020 crypto_freesession(cryptoid); 1021 xd->cryptoid = crp->crp_session; 1022 CURVNET_RESTORE(); 1023 return (crypto_dispatch(crp)); 1024 } 1025 ESPSTAT_INC(esps_noxform); 1026 DPRINTF(("%s: crypto error %d\n", __func__, crp->crp_etype)); 1027 error = crp->crp_etype; 1028 m_freem(m); 1029 goto bad; 1030 } 1031 1032 /* Shouldn't happen... */ 1033 if (m == NULL) { 1034 ESPSTAT_INC(esps_crypto); 1035 DPRINTF(("%s: bogus returned buffer from crypto\n", __func__)); 1036 error = EINVAL; 1037 goto bad; 1038 } 1039 free(xd, M_ESP); 1040 free(crp->crp_aad, M_ESP); 1041 crypto_freereq(crp); 1042 ESPSTAT_INC2(esps_hist, sav->alg_enc); 1043 if (sav->tdb_authalgxform != NULL) 1044 AHSTAT_INC2(ahs_hist, sav->alg_auth); 1045 1046 #ifdef REGRESSION 1047 /* Emulate man-in-the-middle attack when ipsec_integrity is TRUE. */ 1048 if (V_ipsec_integrity) { 1049 static unsigned char ipseczeroes[AH_HMAC_MAXHASHLEN]; 1050 const struct auth_hash *esph; 1051 1052 /* 1053 * Corrupt HMAC if we want to test integrity verification of 1054 * the other side. 1055 */ 1056 esph = sav->tdb_authalgxform; 1057 if (esph != NULL) { 1058 int alen; 1059 1060 alen = xform_ah_authsize(esph); 1061 m_copyback(m, m->m_pkthdr.len - alen, 1062 alen, ipseczeroes); 1063 } 1064 } 1065 #endif 1066 1067 /* NB: m is reclaimed by ipsec_process_done. */ 1068 error = ipsec_process_done(m, sp, sav, idx); 1069 CURVNET_RESTORE(); 1070 return (error); 1071 bad: 1072 free(xd, M_ESP); 1073 free(crp->crp_aad, M_ESP); 1074 crypto_freereq(crp); 1075 key_freesav(&sav); 1076 key_freesp(&sp); 1077 CURVNET_RESTORE(); 1078 return (error); 1079 } 1080 1081 static struct xformsw esp_xformsw = { 1082 .xf_type = XF_ESP, 1083 .xf_name = "IPsec ESP", 1084 .xf_init = esp_init, 1085 .xf_cleanup = esp_cleanup, 1086 .xf_input = esp_input, 1087 .xf_output = esp_output, 1088 }; 1089 1090 SYSINIT(esp_xform_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE, 1091 xform_attach, &esp_xformsw); 1092 SYSUNINIT(esp_xform_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE, 1093 xform_detach, &esp_xformsw); 1094