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 85VNET_DEFINE(int, esp_enable) = 1; 86VNET_DEFINE_STATIC(int, esp_ctr_compatibility) = 1; 87#define V_esp_ctr_compatibility VNET(esp_ctr_compatibility) 88VNET_PCPUSTAT_DEFINE(struct espstat, espstat); 89VNET_PCPUSTAT_SYSINIT(espstat); 90 91#ifdef VIMAGE 92VNET_PCPUSTAT_SYSUNINIT(espstat); 93#endif /* VIMAGE */ 94 95SYSCTL_DECL(_net_inet_esp); 96SYSCTL_INT(_net_inet_esp, OID_AUTO, esp_enable, 97 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(esp_enable), 0, ""); 98SYSCTL_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"); 101SYSCTL_VNET_PCPUSTAT(_net_inet_esp, IPSECCTL_STATS, stats, 102 struct espstat, espstat, 103 "ESP statistics (struct espstat, netipsec/esp_var.h"); 104 105static MALLOC_DEFINE(M_ESP, "esp", "IPsec ESP"); 106 107static int esp_input_cb(struct cryptop *op); 108static int esp_output_cb(struct cryptop *crp); 109 110size_t 111esp_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 */ 144static int 145esp_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 255static void 256esp_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 */ 268static int 269esp_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 477crp_aad_fail: 478 free(xd, M_ESP); 479xd_fail: 480 crypto_freereq(crp); 481 ESPSTAT_INC(esps_crypto); 482 error = ENOBUFS; 483bad: 484 m_freem(m); 485 key_freesav(&sav); 486 return (error); 487} 488 489/* 490 * ESP input callback from the crypto driver. 491 */ 492static int 493esp_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 if (sav->state >= SADB_SASTATE_DEAD) { 512 /* saidx is freed */ 513 DPRINTF(("%s: dead SA %p spi %#x\n", __func__, sav, sav->spi)); 514 ESPSTAT_INC(esps_notdb); 515 error = ESRCH; 516 goto bad; 517 } 518 skip = xd->skip; 519 protoff = xd->protoff; 520 cryptoid = xd->cryptoid; 521 saidx = &sav->sah->saidx; 522 esph = sav->tdb_authalgxform; 523 524 /* Check for crypto errors */ 525 if (crp->crp_etype) { 526 if (crp->crp_etype == EAGAIN) { 527 /* Reset the session ID */ 528 if (ipsec_updateid(sav, &crp->crp_session, &cryptoid) != 0) 529 crypto_freesession(cryptoid); 530 xd->cryptoid = crp->crp_session; 531 CURVNET_RESTORE(); 532 return (crypto_dispatch(crp)); 533 } 534 535 /* EBADMSG indicates authentication failure. */ 536 if (!(crp->crp_etype == EBADMSG && esph != NULL)) { 537 ESPSTAT_INC(esps_noxform); 538 DPRINTF(("%s: crypto error %d\n", __func__, 539 crp->crp_etype)); 540 error = crp->crp_etype; 541 goto bad; 542 } 543 } 544 545 /* Shouldn't happen... */ 546 if (m == NULL) { 547 ESPSTAT_INC(esps_crypto); 548 DPRINTF(("%s: bogus returned buffer from crypto\n", __func__)); 549 error = EINVAL; 550 goto bad; 551 } 552 ESPSTAT_INC(esps_hist[sav->alg_enc]); 553 554 /* If authentication was performed, check now. */ 555 if (esph != NULL) { 556 alen = xform_ah_authsize(esph); 557 AHSTAT_INC(ahs_hist[sav->alg_auth]); 558 if (crp->crp_etype == EBADMSG) { 559 DPRINTF(("%s: authentication hash mismatch for " 560 "packet in SA %s/%08lx\n", __func__, 561 ipsec_address(&saidx->dst, buf, sizeof(buf)), 562 (u_long) ntohl(sav->spi))); 563 ESPSTAT_INC(esps_badauth); 564 error = EACCES; 565 goto bad; 566 } 567 m->m_flags |= M_AUTHIPDGM; 568 /* Remove trailing authenticator */ 569 m_adj(m, -alen); 570 } 571 572 /* Release the crypto descriptors */ 573 free(xd, M_ESP), xd = NULL; 574 free(crp->crp_aad, M_ESP), crp->crp_aad = NULL; 575 crypto_freereq(crp), crp = NULL; 576 577 /* 578 * Packet is now decrypted. 579 */ 580 m->m_flags |= M_DECRYPTED; 581 582 /* 583 * Update replay sequence number, if appropriate. 584 */ 585 if (sav->replay) { 586 u_int32_t seq; 587 588 m_copydata(m, skip + offsetof(struct newesp, esp_seq), 589 sizeof (seq), (caddr_t) &seq); 590 SECASVAR_RLOCK(sav); 591 if (ipsec_updatereplay(ntohl(seq), sav)) { 592 SECASVAR_RUNLOCK(sav); 593 DPRINTF(("%s: packet replay check for %s\n", __func__, 594 ipsec_sa2str(sav, buf, sizeof(buf)))); 595 ESPSTAT_INC(esps_replay); 596 error = EACCES; 597 goto bad; 598 } 599 SECASVAR_RUNLOCK(sav); 600 } 601 602 /* Determine the ESP header length */ 603 if (sav->flags & SADB_X_EXT_OLD) 604 hlen = sizeof (struct esp) + sav->ivlen; 605 else 606 hlen = sizeof (struct newesp) + sav->ivlen; 607 608 /* Remove the ESP header and IV from the mbuf. */ 609 error = m_striphdr(m, skip, hlen); 610 if (error) { 611 ESPSTAT_INC(esps_hdrops); 612 DPRINTF(("%s: bad mbuf chain, SA %s/%08lx\n", __func__, 613 ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)), 614 (u_long) ntohl(sav->spi))); 615 goto bad; 616 } 617 618 /* Save the last three bytes of decrypted data */ 619 m_copydata(m, m->m_pkthdr.len - 3, 3, lastthree); 620 621 /* Verify pad length */ 622 if (lastthree[1] + 2 > m->m_pkthdr.len - skip) { 623 ESPSTAT_INC(esps_badilen); 624 DPRINTF(("%s: invalid padding length %d for %u byte packet " 625 "in SA %s/%08lx\n", __func__, lastthree[1], 626 m->m_pkthdr.len - skip, 627 ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)), 628 (u_long) ntohl(sav->spi))); 629 error = EINVAL; 630 goto bad; 631 } 632 633 /* Verify correct decryption by checking the last padding bytes */ 634 if ((sav->flags & SADB_X_EXT_PMASK) != SADB_X_EXT_PRAND) { 635 if (lastthree[1] != lastthree[0] && lastthree[1] != 0) { 636 ESPSTAT_INC(esps_badenc); 637 DPRINTF(("%s: decryption failed for packet in " 638 "SA %s/%08lx\n", __func__, ipsec_address( 639 &sav->sah->saidx.dst, buf, sizeof(buf)), 640 (u_long) ntohl(sav->spi))); 641 error = EINVAL; 642 goto bad; 643 } 644 } 645 646 /* 647 * RFC4303 2.6: 648 * Silently drop packet if next header field is IPPROTO_NONE. 649 */ 650 if (lastthree[2] == IPPROTO_NONE) 651 goto bad; 652 653 /* Trim the mbuf chain to remove trailing authenticator and padding */ 654 m_adj(m, -(lastthree[1] + 2)); 655 656 /* Restore the Next Protocol field */ 657 m_copyback(m, protoff, sizeof (u_int8_t), lastthree + 2); 658 659 switch (saidx->dst.sa.sa_family) { 660#ifdef INET6 661 case AF_INET6: 662 error = ipsec6_common_input_cb(m, sav, skip, protoff); 663 break; 664#endif 665#ifdef INET 666 case AF_INET: 667 error = ipsec4_common_input_cb(m, sav, skip, protoff); 668 break; 669#endif 670 default: 671 panic("%s: Unexpected address family: %d saidx=%p", __func__, 672 saidx->dst.sa.sa_family, saidx); 673 } 674 CURVNET_RESTORE(); 675 return error; 676bad: 677 if (sav != NULL) 678 key_freesav(&sav); 679 if (m != NULL) 680 m_freem(m); 681 if (xd != NULL) 682 free(xd, M_ESP); 683 if (crp != NULL) { 684 free(crp->crp_aad, M_ESP); 685 crypto_freereq(crp); 686 } 687 CURVNET_RESTORE(); 688 return error; 689} 690/* 691 * ESP output routine, called by ipsec[46]_perform_request(). 692 */ 693static int 694esp_output(struct mbuf *m, struct secpolicy *sp, struct secasvar *sav, 695 u_int idx, int skip, int protoff) 696{ 697 IPSEC_DEBUG_DECLARE(char buf[IPSEC_ADDRSTRLEN]); 698 struct cryptop *crp; 699 const struct auth_hash *esph; 700 const struct enc_xform *espx; 701 struct mbuf *mo = NULL; 702 struct xform_data *xd; 703 struct secasindex *saidx; 704 unsigned char *pad; 705 uint8_t *ivp; 706 uint64_t cntr; 707 crypto_session_t cryptoid; 708 int hlen, rlen, padding, blks, alen, i, roff; 709 int error, maxpacketsize; 710 uint8_t prot; 711 uint32_t seqh; 712 const struct crypto_session_params *csp; 713 714 SECASVAR_RLOCK_TRACKER; 715 716 IPSEC_ASSERT(sav != NULL, ("null SA")); 717 esph = sav->tdb_authalgxform; 718 espx = sav->tdb_encalgxform; 719 IPSEC_ASSERT(espx != NULL, ("null encoding xform")); 720 721 if (sav->flags & SADB_X_EXT_OLD) 722 hlen = sizeof (struct esp) + sav->ivlen; 723 else 724 hlen = sizeof (struct newesp) + sav->ivlen; 725 726 rlen = m->m_pkthdr.len - skip; /* Raw payload length. */ 727 /* 728 * RFC4303 2.4 Requires 4 byte alignment. 729 * Old versions of FreeBSD can't decrypt partial blocks encrypted 730 * with AES-CTR. Align payload to native_blocksize (16 bytes) 731 * in order to preserve compatibility. 732 */ 733 if (SAV_ISCTR(sav) && V_esp_ctr_compatibility) 734 blks = MAX(4, espx->native_blocksize); /* Cipher blocksize */ 735 else 736 blks = MAX(4, espx->blocksize); 737 738 /* XXX clamp padding length a la KAME??? */ 739 padding = ((blks - ((rlen + 2) % blks)) % blks) + 2; 740 741 alen = xform_ah_authsize(esph); 742 743 ESPSTAT_INC(esps_output); 744 745 saidx = &sav->sah->saidx; 746 /* Check for maximum packet size violations. */ 747 switch (saidx->dst.sa.sa_family) { 748#ifdef INET 749 case AF_INET: 750 maxpacketsize = IP_MAXPACKET; 751 break; 752#endif /* INET */ 753#ifdef INET6 754 case AF_INET6: 755 maxpacketsize = IPV6_MAXPACKET; 756 break; 757#endif /* INET6 */ 758 default: 759 DPRINTF(("%s: unknown/unsupported protocol " 760 "family %d, SA %s/%08lx\n", __func__, 761 saidx->dst.sa.sa_family, ipsec_address(&saidx->dst, 762 buf, sizeof(buf)), (u_long) ntohl(sav->spi))); 763 ESPSTAT_INC(esps_nopf); 764 error = EPFNOSUPPORT; 765 goto bad; 766 } 767 /* 768 DPRINTF(("%s: skip %d hlen %d rlen %d padding %d alen %d blksd %d\n", 769 __func__, skip, hlen, rlen, padding, alen, blks)); */ 770 if (skip + hlen + rlen + padding + alen > maxpacketsize) { 771 DPRINTF(("%s: packet in SA %s/%08lx got too big " 772 "(len %u, max len %u)\n", __func__, 773 ipsec_address(&saidx->dst, buf, sizeof(buf)), 774 (u_long) ntohl(sav->spi), 775 skip + hlen + rlen + padding + alen, maxpacketsize)); 776 ESPSTAT_INC(esps_toobig); 777 error = EMSGSIZE; 778 goto bad; 779 } 780 781 /* Update the counters. */ 782 ESPSTAT_ADD(esps_obytes, m->m_pkthdr.len - skip); 783 784 m = m_unshare(m, M_NOWAIT); 785 if (m == NULL) { 786 DPRINTF(("%s: cannot clone mbuf chain, SA %s/%08lx\n", __func__, 787 ipsec_address(&saidx->dst, buf, sizeof(buf)), 788 (u_long) ntohl(sav->spi))); 789 ESPSTAT_INC(esps_hdrops); 790 error = ENOBUFS; 791 goto bad; 792 } 793 794 /* Inject ESP header. */ 795 mo = m_makespace(m, skip, hlen, &roff); 796 if (mo == NULL) { 797 DPRINTF(("%s: %u byte ESP hdr inject failed for SA %s/%08lx\n", 798 __func__, hlen, ipsec_address(&saidx->dst, buf, 799 sizeof(buf)), (u_long) ntohl(sav->spi))); 800 ESPSTAT_INC(esps_hdrops); /* XXX diffs from openbsd */ 801 error = ENOBUFS; 802 goto bad; 803 } 804 805 /* Initialize ESP header. */ 806 bcopy((caddr_t) &sav->spi, mtod(mo, caddr_t) + roff, 807 sizeof(uint32_t)); 808 SECASVAR_RLOCK(sav); 809 if (sav->replay) { 810 uint32_t replay; 811 812 SECREPLAY_LOCK(sav->replay); 813#ifdef REGRESSION 814 /* Emulate replay attack when ipsec_replay is TRUE. */ 815 if (!V_ipsec_replay) 816#endif 817 sav->replay->count++; 818 replay = htonl((uint32_t)sav->replay->count); 819 820 bcopy((caddr_t) &replay, mtod(mo, caddr_t) + roff + 821 sizeof(uint32_t), sizeof(uint32_t)); 822 823 seqh = htonl((uint32_t)(sav->replay->count >> IPSEC_SEQH_SHIFT)); 824 SECREPLAY_UNLOCK(sav->replay); 825 } 826 cryptoid = sav->tdb_cryptoid; 827 if (SAV_ISCTRORGCM(sav) || SAV_ISCHACHA(sav)) 828 cntr = sav->cntr++; 829 SECASVAR_RUNLOCK(sav); 830 831 /* 832 * Add padding -- better to do it ourselves than use the crypto engine, 833 * although if/when we support compression, we'd have to do that. 834 */ 835 pad = (u_char *) m_pad(m, padding + alen); 836 if (pad == NULL) { 837 DPRINTF(("%s: m_pad failed for SA %s/%08lx\n", __func__, 838 ipsec_address(&saidx->dst, buf, sizeof(buf)), 839 (u_long) ntohl(sav->spi))); 840 m = NULL; /* NB: free'd by m_pad */ 841 error = ENOBUFS; 842 goto bad; 843 } 844 845 /* 846 * Add padding: random, zero, or self-describing. 847 * XXX catch unexpected setting 848 */ 849 switch (sav->flags & SADB_X_EXT_PMASK) { 850 case SADB_X_EXT_PRAND: 851 arc4random_buf(pad, padding - 2); 852 break; 853 case SADB_X_EXT_PZERO: 854 bzero(pad, padding - 2); 855 break; 856 case SADB_X_EXT_PSEQ: 857 for (i = 0; i < padding - 2; i++) 858 pad[i] = i+1; 859 break; 860 } 861 862 /* Fix padding length and Next Protocol in padding itself. */ 863 pad[padding - 2] = padding - 2; 864 m_copydata(m, protoff, sizeof(u_int8_t), pad + padding - 1); 865 866 /* Fix Next Protocol in IPv4/IPv6 header. */ 867 prot = IPPROTO_ESP; 868 m_copyback(m, protoff, sizeof(u_int8_t), (u_char *) &prot); 869 870 /* Get crypto descriptor. */ 871 crp = crypto_getreq(cryptoid, M_NOWAIT); 872 if (crp == NULL) { 873 DPRINTF(("%s: failed to acquire crypto descriptor\n", 874 __func__)); 875 ESPSTAT_INC(esps_crypto); 876 error = ENOBUFS; 877 goto bad; 878 } 879 880 /* IPsec-specific opaque crypto info. */ 881 xd = malloc(sizeof(struct xform_data), M_ESP, M_NOWAIT | M_ZERO); 882 if (xd == NULL) { 883 DPRINTF(("%s: failed to allocate xform_data\n", __func__)); 884 goto xd_fail; 885 } 886 887 /* Encryption descriptor. */ 888 crp->crp_payload_start = skip + hlen; 889 crp->crp_payload_length = m->m_pkthdr.len - (skip + hlen + alen); 890 crp->crp_op = CRYPTO_OP_ENCRYPT; 891 892 /* Generate cipher and ESP IVs. */ 893 ivp = &crp->crp_iv[0]; 894 if (SAV_ISCTRORGCM(sav) || SAV_ISCHACHA(sav)) { 895 /* 896 * See comment in esp_input() for details on the 897 * cipher IV. A simple per-SA counter stored in 898 * 'cntr' is used as the explicit ESP IV. 899 */ 900 memcpy(ivp, sav->key_enc->key_data + 901 _KEYLEN(sav->key_enc) - 4, 4); 902 be64enc(&ivp[4], cntr); 903 if (SAV_ISCTR(sav)) { 904 be32enc(&ivp[sav->ivlen + 4], 1); 905 } 906 m_copyback(m, skip + hlen - sav->ivlen, sav->ivlen, &ivp[4]); 907 crp->crp_flags |= CRYPTO_F_IV_SEPARATE; 908 } else if (sav->ivlen != 0) { 909 arc4rand(ivp, sav->ivlen, 0); 910 crp->crp_iv_start = skip + hlen - sav->ivlen; 911 m_copyback(m, crp->crp_iv_start, sav->ivlen, ivp); 912 } 913 914 /* Callback parameters */ 915 xd->sp = sp; 916 xd->sav = sav; 917 xd->idx = idx; 918 xd->cryptoid = cryptoid; 919 xd->vnet = curvnet; 920 921 /* Crypto operation descriptor. */ 922 crp->crp_flags |= CRYPTO_F_CBIFSYNC; 923 crypto_use_mbuf(crp, m); 924 crp->crp_callback = esp_output_cb; 925 crp->crp_opaque = xd; 926 927 if (esph) { 928 /* Authentication descriptor. */ 929 crp->crp_op |= CRYPTO_OP_COMPUTE_DIGEST; 930 if (SAV_ISGCM(sav) || SAV_ISCHACHA(sav)) 931 crp->crp_aad_length = 8; /* RFC4106 5, SPI + SN */ 932 else 933 crp->crp_aad_length = hlen; 934 935 csp = crypto_get_params(crp->crp_session); 936 if (csp->csp_flags & CSP_F_SEPARATE_AAD && 937 sav->replay != NULL) { 938 int aad_skip; 939 940 crp->crp_aad_length += sizeof(seqh); 941 crp->crp_aad = malloc(crp->crp_aad_length, M_ESP, M_NOWAIT); 942 if (crp->crp_aad == NULL) { 943 DPRINTF(("%s: failed to allocate xform_data\n", 944 __func__)); 945 goto crp_aad_fail; 946 } 947 948 /* SPI */ 949 m_copydata(m, skip, SPI_SIZE, crp->crp_aad); 950 aad_skip = SPI_SIZE; 951 952 /* ESN */ 953 bcopy(&seqh, (char *)crp->crp_aad + aad_skip, sizeof(seqh)); 954 aad_skip += sizeof(seqh); 955 956 /* Rest of aad */ 957 if (crp->crp_aad_length - aad_skip > 0) 958 m_copydata(m, skip + SPI_SIZE, 959 crp->crp_aad_length - aad_skip, 960 (char *)crp->crp_aad + aad_skip); 961 } else 962 crp->crp_aad_start = skip; 963 964 if (csp->csp_flags & CSP_F_ESN && sav->replay != NULL) 965 memcpy(crp->crp_esn, &seqh, sizeof(seqh)); 966 967 crp->crp_digest_start = m->m_pkthdr.len - alen; 968 } 969 970 if (V_async_crypto) 971 return (crypto_dispatch_async(crp, CRYPTO_ASYNC_ORDERED)); 972 else 973 return (crypto_dispatch(crp)); 974 975crp_aad_fail: 976 free(xd, M_ESP); 977xd_fail: 978 crypto_freereq(crp); 979 ESPSTAT_INC(esps_crypto); 980 error = ENOBUFS; 981bad: 982 if (m) 983 m_freem(m); 984 key_freesav(&sav); 985 key_freesp(&sp); 986 return (error); 987} 988/* 989 * ESP output callback from the crypto driver. 990 */ 991static int 992esp_output_cb(struct cryptop *crp) 993{ 994 struct xform_data *xd; 995 struct secpolicy *sp; 996 struct secasvar *sav; 997 struct mbuf *m; 998 crypto_session_t cryptoid; 999 u_int idx; 1000 int error; 1001 1002 xd = (struct xform_data *) crp->crp_opaque; 1003 CURVNET_SET(xd->vnet); 1004 m = crp->crp_buf.cb_mbuf; 1005 sp = xd->sp; 1006 sav = xd->sav; 1007 idx = xd->idx; 1008 cryptoid = xd->cryptoid; 1009 1010 /* Check for crypto errors. */ 1011 if (crp->crp_etype) { 1012 if (crp->crp_etype == EAGAIN) { 1013 /* Reset the session ID */ 1014 if (ipsec_updateid(sav, &crp->crp_session, &cryptoid) != 0) 1015 crypto_freesession(cryptoid); 1016 xd->cryptoid = crp->crp_session; 1017 CURVNET_RESTORE(); 1018 return (crypto_dispatch(crp)); 1019 } 1020 ESPSTAT_INC(esps_noxform); 1021 DPRINTF(("%s: crypto error %d\n", __func__, crp->crp_etype)); 1022 error = crp->crp_etype; 1023 m_freem(m); 1024 goto bad; 1025 } 1026 1027 /* Shouldn't happen... */ 1028 if (m == NULL) { 1029 ESPSTAT_INC(esps_crypto); 1030 DPRINTF(("%s: bogus returned buffer from crypto\n", __func__)); 1031 error = EINVAL; 1032 goto bad; 1033 } 1034 free(xd, M_ESP); 1035 free(crp->crp_aad, M_ESP); 1036 crypto_freereq(crp); 1037 ESPSTAT_INC(esps_hist[sav->alg_enc]); 1038 if (sav->tdb_authalgxform != NULL) 1039 AHSTAT_INC(ahs_hist[sav->alg_auth]); 1040 1041#ifdef REGRESSION 1042 /* Emulate man-in-the-middle attack when ipsec_integrity is TRUE. */ 1043 if (V_ipsec_integrity) { 1044 static unsigned char ipseczeroes[AH_HMAC_MAXHASHLEN]; 1045 const struct auth_hash *esph; 1046 1047 /* 1048 * Corrupt HMAC if we want to test integrity verification of 1049 * the other side. 1050 */ 1051 esph = sav->tdb_authalgxform; 1052 if (esph != NULL) { 1053 int alen; 1054 1055 alen = xform_ah_authsize(esph); 1056 m_copyback(m, m->m_pkthdr.len - alen, 1057 alen, ipseczeroes); 1058 } 1059 } 1060#endif 1061 1062 /* NB: m is reclaimed by ipsec_process_done. */ 1063 error = ipsec_process_done(m, sp, sav, idx); 1064 CURVNET_RESTORE(); 1065 return (error); 1066bad: 1067 free(xd, M_ESP); 1068 free(crp->crp_aad, M_ESP); 1069 crypto_freereq(crp); 1070 key_freesav(&sav); 1071 key_freesp(&sp); 1072 CURVNET_RESTORE(); 1073 return (error); 1074} 1075 1076static struct xformsw esp_xformsw = { 1077 .xf_type = XF_ESP, 1078 .xf_name = "IPsec ESP", 1079 .xf_init = esp_init, 1080 .xf_cleanup = esp_cleanup, 1081 .xf_input = esp_input, 1082 .xf_output = esp_output, 1083}; 1084 1085SYSINIT(esp_xform_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE, 1086 xform_attach, &esp_xformsw); 1087SYSUNINIT(esp_xform_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE, 1088 xform_detach, &esp_xformsw); 1089