1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* Kerberos-based RxRPC security 3 * 4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 9 10 #include <crypto/skcipher.h> 11 #include <linux/module.h> 12 #include <linux/net.h> 13 #include <linux/skbuff.h> 14 #include <linux/udp.h> 15 #include <linux/scatterlist.h> 16 #include <linux/ctype.h> 17 #include <linux/slab.h> 18 #include <linux/key-type.h> 19 #include <net/sock.h> 20 #include <net/af_rxrpc.h> 21 #include <keys/rxrpc-type.h> 22 #include "ar-internal.h" 23 24 #define RXKAD_VERSION 2 25 #define MAXKRB5TICKETLEN 1024 26 #define RXKAD_TKT_TYPE_KERBEROS_V5 256 27 #define ANAME_SZ 40 /* size of authentication name */ 28 #define INST_SZ 40 /* size of principal's instance */ 29 #define REALM_SZ 40 /* size of principal's auth domain */ 30 #define SNAME_SZ 40 /* size of service name */ 31 #define RXKAD_ALIGN 8 32 33 struct rxkad_level1_hdr { 34 __be32 data_size; /* true data size (excluding padding) */ 35 }; 36 37 struct rxkad_level2_hdr { 38 __be32 data_size; /* true data size (excluding padding) */ 39 __be32 checksum; /* decrypted data checksum */ 40 }; 41 42 static int rxkad_prime_packet_security(struct rxrpc_connection *conn, 43 struct crypto_sync_skcipher *ci); 44 45 /* 46 * this holds a pinned cipher so that keventd doesn't get called by the cipher 47 * alloc routine, but since we have it to hand, we use it to decrypt RESPONSE 48 * packets 49 */ 50 static struct crypto_sync_skcipher *rxkad_ci; 51 static struct skcipher_request *rxkad_ci_req; 52 static DEFINE_MUTEX(rxkad_ci_mutex); 53 54 /* 55 * Parse the information from a server key 56 * 57 * The data should be the 8-byte secret key. 58 */ 59 static int rxkad_preparse_server_key(struct key_preparsed_payload *prep) 60 { 61 struct crypto_skcipher *ci; 62 63 if (prep->datalen != 8) 64 return -EINVAL; 65 66 memcpy(&prep->payload.data[2], prep->data, 8); 67 68 ci = crypto_alloc_skcipher("pcbc(des)", 0, CRYPTO_ALG_ASYNC); 69 if (IS_ERR(ci)) { 70 _leave(" = %ld", PTR_ERR(ci)); 71 return PTR_ERR(ci); 72 } 73 74 if (crypto_skcipher_setkey(ci, prep->data, 8) < 0) 75 BUG(); 76 77 prep->payload.data[0] = ci; 78 _leave(" = 0"); 79 return 0; 80 } 81 82 static void rxkad_free_preparse_server_key(struct key_preparsed_payload *prep) 83 { 84 85 if (prep->payload.data[0]) 86 crypto_free_skcipher(prep->payload.data[0]); 87 } 88 89 static void rxkad_destroy_server_key(struct key *key) 90 { 91 if (key->payload.data[0]) { 92 crypto_free_skcipher(key->payload.data[0]); 93 key->payload.data[0] = NULL; 94 } 95 } 96 97 /* 98 * initialise connection security 99 */ 100 static int rxkad_init_connection_security(struct rxrpc_connection *conn, 101 struct rxrpc_key_token *token) 102 { 103 struct crypto_sync_skcipher *ci; 104 int ret; 105 106 _enter("{%d},{%x}", conn->debug_id, key_serial(conn->key)); 107 108 conn->security_ix = token->security_index; 109 110 ci = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0); 111 if (IS_ERR(ci)) { 112 _debug("no cipher"); 113 ret = PTR_ERR(ci); 114 goto error; 115 } 116 117 if (crypto_sync_skcipher_setkey(ci, token->kad->session_key, 118 sizeof(token->kad->session_key)) < 0) 119 BUG(); 120 121 switch (conn->security_level) { 122 case RXRPC_SECURITY_PLAIN: 123 case RXRPC_SECURITY_AUTH: 124 case RXRPC_SECURITY_ENCRYPT: 125 break; 126 default: 127 ret = -EKEYREJECTED; 128 goto error; 129 } 130 131 ret = rxkad_prime_packet_security(conn, ci); 132 if (ret < 0) 133 goto error_ci; 134 135 conn->rxkad.cipher = ci; 136 return 0; 137 138 error_ci: 139 crypto_free_sync_skcipher(ci); 140 error: 141 _leave(" = %d", ret); 142 return ret; 143 } 144 145 /* 146 * Work out how much data we can put in a packet. 147 */ 148 static struct rxrpc_txbuf *rxkad_alloc_txbuf(struct rxrpc_call *call, size_t remain, gfp_t gfp) 149 { 150 struct rxrpc_txbuf *txb; 151 size_t shdr, alloc, limit, part; 152 153 remain = umin(remain, 65535 - sizeof(struct rxrpc_wire_header)); 154 155 switch (call->conn->security_level) { 156 default: 157 alloc = umin(remain, RXRPC_JUMBO_DATALEN); 158 return rxrpc_alloc_data_txbuf(call, alloc, 1, gfp); 159 case RXRPC_SECURITY_AUTH: 160 shdr = sizeof(struct rxkad_level1_hdr); 161 break; 162 case RXRPC_SECURITY_ENCRYPT: 163 shdr = sizeof(struct rxkad_level2_hdr); 164 break; 165 } 166 167 limit = round_down(RXRPC_JUMBO_DATALEN, RXKAD_ALIGN) - shdr; 168 if (remain < limit) { 169 part = remain; 170 alloc = round_up(shdr + part, RXKAD_ALIGN); 171 } else { 172 part = limit; 173 alloc = RXRPC_JUMBO_DATALEN; 174 } 175 176 txb = rxrpc_alloc_data_txbuf(call, alloc, RXKAD_ALIGN, gfp); 177 if (!txb) 178 return NULL; 179 180 txb->crypto_header = 0; 181 txb->sec_header = shdr; 182 txb->offset += shdr; 183 txb->space = part; 184 return txb; 185 } 186 187 /* 188 * prime the encryption state with the invariant parts of a connection's 189 * description 190 */ 191 static int rxkad_prime_packet_security(struct rxrpc_connection *conn, 192 struct crypto_sync_skcipher *ci) 193 { 194 struct skcipher_request *req; 195 struct rxrpc_key_token *token; 196 struct scatterlist sg; 197 struct rxrpc_crypt iv; 198 __be32 *tmpbuf; 199 size_t tmpsize = 4 * sizeof(__be32); 200 int ret; 201 202 _enter(""); 203 204 if (!conn->key) 205 return 0; 206 207 tmpbuf = kmalloc(tmpsize, GFP_KERNEL); 208 if (!tmpbuf) 209 return -ENOMEM; 210 211 req = skcipher_request_alloc(&ci->base, GFP_NOFS); 212 if (!req) { 213 kfree(tmpbuf); 214 return -ENOMEM; 215 } 216 217 token = conn->key->payload.data[0]; 218 memcpy(&iv, token->kad->session_key, sizeof(iv)); 219 220 tmpbuf[0] = htonl(conn->proto.epoch); 221 tmpbuf[1] = htonl(conn->proto.cid); 222 tmpbuf[2] = 0; 223 tmpbuf[3] = htonl(conn->security_ix); 224 225 sg_init_one(&sg, tmpbuf, tmpsize); 226 skcipher_request_set_sync_tfm(req, ci); 227 skcipher_request_set_callback(req, 0, NULL, NULL); 228 skcipher_request_set_crypt(req, &sg, &sg, tmpsize, iv.x); 229 ret = crypto_skcipher_encrypt(req); 230 skcipher_request_free(req); 231 232 memcpy(&conn->rxkad.csum_iv, tmpbuf + 2, sizeof(conn->rxkad.csum_iv)); 233 kfree(tmpbuf); 234 _leave(" = %d", ret); 235 return ret; 236 } 237 238 /* 239 * Allocate and prepare the crypto request on a call. For any particular call, 240 * this is called serially for the packets, so no lock should be necessary. 241 */ 242 static struct skcipher_request *rxkad_get_call_crypto(struct rxrpc_call *call) 243 { 244 struct crypto_skcipher *tfm = &call->conn->rxkad.cipher->base; 245 246 return skcipher_request_alloc(tfm, GFP_NOFS); 247 } 248 249 /* 250 * Clean up the crypto on a call. 251 */ 252 static void rxkad_free_call_crypto(struct rxrpc_call *call) 253 { 254 } 255 256 /* 257 * partially encrypt a packet (level 1 security) 258 */ 259 static int rxkad_secure_packet_auth(const struct rxrpc_call *call, 260 struct rxrpc_txbuf *txb, 261 struct skcipher_request *req) 262 { 263 struct rxkad_level1_hdr *hdr = txb->data; 264 struct rxrpc_crypt iv; 265 struct scatterlist sg; 266 size_t pad; 267 u16 check; 268 int ret; 269 270 _enter(""); 271 272 check = txb->seq ^ call->call_id; 273 hdr->data_size = htonl((u32)check << 16 | txb->len); 274 275 txb->pkt_len = sizeof(struct rxkad_level1_hdr) + txb->len; 276 pad = txb->pkt_len; 277 pad = RXKAD_ALIGN - pad; 278 pad &= RXKAD_ALIGN - 1; 279 if (pad) { 280 memset(txb->data + txb->offset, 0, pad); 281 txb->pkt_len += pad; 282 } 283 284 /* start the encryption afresh */ 285 memset(&iv, 0, sizeof(iv)); 286 287 sg_init_one(&sg, hdr, 8); 288 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 289 skcipher_request_set_callback(req, 0, NULL, NULL); 290 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x); 291 ret = crypto_skcipher_encrypt(req); 292 skcipher_request_zero(req); 293 294 _leave(" = %d", ret); 295 return ret; 296 } 297 298 /* 299 * wholly encrypt a packet (level 2 security) 300 */ 301 static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call, 302 struct rxrpc_txbuf *txb, 303 struct skcipher_request *req) 304 { 305 const struct rxrpc_key_token *token; 306 struct rxkad_level2_hdr *rxkhdr = txb->data; 307 struct rxrpc_crypt iv; 308 struct scatterlist sg; 309 size_t content, pad; 310 u16 check; 311 int ret; 312 313 _enter(""); 314 315 check = txb->seq ^ call->call_id; 316 317 rxkhdr->data_size = htonl(txb->len | (u32)check << 16); 318 rxkhdr->checksum = 0; 319 320 content = sizeof(struct rxkad_level2_hdr) + txb->len; 321 txb->pkt_len = round_up(content, RXKAD_ALIGN); 322 pad = txb->pkt_len - content; 323 if (pad) 324 memset(txb->data + txb->offset, 0, pad); 325 326 /* encrypt from the session key */ 327 token = call->conn->key->payload.data[0]; 328 memcpy(&iv, token->kad->session_key, sizeof(iv)); 329 330 sg_init_one(&sg, rxkhdr, txb->pkt_len); 331 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 332 skcipher_request_set_callback(req, 0, NULL, NULL); 333 skcipher_request_set_crypt(req, &sg, &sg, txb->pkt_len, iv.x); 334 ret = crypto_skcipher_encrypt(req); 335 skcipher_request_zero(req); 336 return ret; 337 } 338 339 /* 340 * checksum an RxRPC packet header 341 */ 342 static int rxkad_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb) 343 { 344 struct skcipher_request *req; 345 struct rxrpc_crypt iv; 346 struct scatterlist sg; 347 union { 348 __be32 buf[2]; 349 } crypto __aligned(8); 350 u32 x, y = 0; 351 int ret; 352 353 _enter("{%d{%x}},{#%u},%u,", 354 call->debug_id, key_serial(call->conn->key), 355 txb->seq, txb->len); 356 357 if (!call->conn->rxkad.cipher) 358 return 0; 359 360 ret = key_validate(call->conn->key); 361 if (ret < 0) 362 return ret; 363 364 req = rxkad_get_call_crypto(call); 365 if (!req) 366 return -ENOMEM; 367 368 /* continue encrypting from where we left off */ 369 memcpy(&iv, call->conn->rxkad.csum_iv.x, sizeof(iv)); 370 371 /* calculate the security checksum */ 372 x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT); 373 x |= txb->seq & 0x3fffffff; 374 crypto.buf[0] = htonl(call->call_id); 375 crypto.buf[1] = htonl(x); 376 377 sg_init_one(&sg, crypto.buf, 8); 378 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 379 skcipher_request_set_callback(req, 0, NULL, NULL); 380 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x); 381 ret = crypto_skcipher_encrypt(req); 382 skcipher_request_zero(req); 383 if (ret < 0) 384 goto out; 385 386 y = ntohl(crypto.buf[1]); 387 y = (y >> 16) & 0xffff; 388 if (y == 0) 389 y = 1; /* zero checksums are not permitted */ 390 txb->cksum = htons(y); 391 392 switch (call->conn->security_level) { 393 case RXRPC_SECURITY_PLAIN: 394 txb->pkt_len = txb->len; 395 ret = 0; 396 break; 397 case RXRPC_SECURITY_AUTH: 398 ret = rxkad_secure_packet_auth(call, txb, req); 399 if (txb->alloc_size == RXRPC_JUMBO_DATALEN) 400 txb->jumboable = true; 401 break; 402 case RXRPC_SECURITY_ENCRYPT: 403 ret = rxkad_secure_packet_encrypt(call, txb, req); 404 if (txb->alloc_size == RXRPC_JUMBO_DATALEN) 405 txb->jumboable = true; 406 break; 407 default: 408 ret = -EPERM; 409 break; 410 } 411 412 /* Clear excess space in the packet */ 413 if (txb->pkt_len < txb->alloc_size) { 414 size_t gap = txb->alloc_size - txb->pkt_len; 415 void *p = txb->data; 416 417 memset(p + txb->pkt_len, 0, gap); 418 } 419 420 out: 421 skcipher_request_free(req); 422 _leave(" = %d [set %x]", ret, y); 423 return ret; 424 } 425 426 /* 427 * decrypt partial encryption on a packet (level 1 security) 428 */ 429 static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb, 430 rxrpc_seq_t seq, 431 struct skcipher_request *req) 432 { 433 struct rxkad_level1_hdr *sechdr; 434 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 435 struct rxrpc_crypt iv; 436 struct scatterlist sg[1]; 437 void *data = call->rx_dec_buffer; 438 u32 len = sp->len, data_size, buf; 439 u16 check; 440 int ret; 441 442 _enter(""); 443 444 if (len < 8) 445 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON, 446 rxkad_abort_1_short_header); 447 448 /* Decrypt the skbuff in-place. TODO: We really want to decrypt 449 * directly into the target buffer. 450 */ 451 sg_init_one(sg, data, len); 452 453 /* start the decryption afresh */ 454 memset(&iv, 0, sizeof(iv)); 455 456 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 457 skcipher_request_set_callback(req, 0, NULL, NULL); 458 skcipher_request_set_crypt(req, sg, sg, 8, iv.x); 459 ret = crypto_skcipher_decrypt(req); 460 skcipher_request_zero(req); 461 if (ret < 0) 462 return ret; 463 464 /* Extract the decrypted packet length */ 465 sechdr = data; 466 call->rx_dec_offset = sizeof(*sechdr); 467 len -= sizeof(*sechdr); 468 469 buf = ntohl(sechdr->data_size); 470 data_size = buf & 0xffff; 471 472 check = buf >> 16; 473 check ^= seq ^ call->call_id; 474 check &= 0xffff; 475 if (check != 0) 476 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON, 477 rxkad_abort_1_short_check); 478 if (data_size > len) 479 return rxrpc_abort_eproto(call, skb, RXKADDATALEN, 480 rxkad_abort_1_short_data); 481 call->rx_dec_len = data_size; 482 483 _leave(" = 0 [dlen=%x]", data_size); 484 return 0; 485 } 486 487 /* 488 * wholly decrypt a packet (level 2 security) 489 */ 490 static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb, 491 rxrpc_seq_t seq, 492 struct skcipher_request *req) 493 { 494 const struct rxrpc_key_token *token; 495 struct rxkad_level2_hdr *sechdr; 496 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 497 struct rxrpc_crypt iv; 498 struct scatterlist sg[1]; 499 void *data = call->rx_dec_buffer; 500 u32 len = sp->len, data_size, buf; 501 u16 check; 502 int ret; 503 504 _enter(",{%d}", len); 505 506 if (len < 8) 507 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON, 508 rxkad_abort_2_short_header); 509 510 /* Don't let the crypto algo see a misaligned length. */ 511 len = round_down(len, 8); 512 513 /* Decrypt in place in the call's decryption buffer. TODO: We really 514 * want to decrypt directly into the target buffer. 515 */ 516 sg_init_one(sg, data, len); 517 518 /* decrypt from the session key */ 519 token = call->conn->key->payload.data[0]; 520 memcpy(&iv, token->kad->session_key, sizeof(iv)); 521 522 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 523 skcipher_request_set_callback(req, 0, NULL, NULL); 524 skcipher_request_set_crypt(req, sg, sg, len, iv.x); 525 ret = crypto_skcipher_decrypt(req); 526 skcipher_request_zero(req); 527 if (ret < 0) { 528 if (ret == -ENOMEM) 529 return ret; 530 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON, 531 rxkad_abort_2_crypto_unaligned); 532 } 533 534 /* Extract the decrypted packet length */ 535 sechdr = data; 536 call->rx_dec_offset = sizeof(*sechdr); 537 len -= sizeof(*sechdr); 538 539 buf = ntohl(sechdr->data_size); 540 data_size = buf & 0xffff; 541 542 check = buf >> 16; 543 check ^= seq ^ call->call_id; 544 check &= 0xffff; 545 if (check != 0) 546 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON, 547 rxkad_abort_2_short_check); 548 549 if (data_size > len) 550 return rxrpc_abort_eproto(call, skb, RXKADDATALEN, 551 rxkad_abort_2_short_data); 552 553 call->rx_dec_len = data_size; 554 _leave(" = 0 [dlen=%x]", data_size); 555 return 0; 556 } 557 558 /* 559 * Verify the security on a received (sub)packet. If the packet needs 560 * modifying (e.g. decrypting), it must be copied. 561 */ 562 static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb) 563 { 564 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 565 struct skcipher_request *req; 566 struct rxrpc_crypt iv; 567 struct scatterlist sg; 568 union { 569 __be32 buf[2]; 570 } crypto __aligned(8); 571 rxrpc_seq_t seq = sp->hdr.seq; 572 int ret; 573 u16 cksum; 574 u32 x, y; 575 576 _enter("{%d{%x}},{#%u}", 577 call->debug_id, key_serial(call->conn->key), seq); 578 579 if (!call->conn->rxkad.cipher) 580 return 0; 581 582 req = rxkad_get_call_crypto(call); 583 if (!req) 584 return -ENOMEM; 585 586 /* continue encrypting from where we left off */ 587 memcpy(&iv, call->conn->rxkad.csum_iv.x, sizeof(iv)); 588 589 /* validate the security checksum */ 590 x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT); 591 x |= seq & 0x3fffffff; 592 crypto.buf[0] = htonl(call->call_id); 593 crypto.buf[1] = htonl(x); 594 595 sg_init_one(&sg, crypto.buf, 8); 596 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 597 skcipher_request_set_callback(req, 0, NULL, NULL); 598 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x); 599 ret = crypto_skcipher_encrypt(req); 600 skcipher_request_zero(req); 601 if (ret < 0) 602 goto out; 603 604 y = ntohl(crypto.buf[1]); 605 cksum = (y >> 16) & 0xffff; 606 if (cksum == 0) 607 cksum = 1; /* zero checksums are not permitted */ 608 609 if (cksum != sp->hdr.cksum) { 610 ret = rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON, 611 rxkad_abort_bad_checksum); 612 goto out; 613 } 614 615 switch (call->conn->security_level) { 616 case RXRPC_SECURITY_PLAIN: 617 ret = 0; 618 break; 619 case RXRPC_SECURITY_AUTH: 620 ret = rxkad_verify_packet_1(call, skb, seq, req); 621 break; 622 case RXRPC_SECURITY_ENCRYPT: 623 ret = rxkad_verify_packet_2(call, skb, seq, req); 624 break; 625 default: 626 ret = -ENOANO; 627 break; 628 } 629 630 out: 631 skcipher_request_free(req); 632 return ret; 633 } 634 635 /* 636 * issue a challenge 637 */ 638 static int rxkad_issue_challenge(struct rxrpc_connection *conn) 639 { 640 struct rxkad_challenge challenge; 641 struct rxrpc_wire_header whdr; 642 struct msghdr msg; 643 struct kvec iov[2]; 644 size_t len; 645 u32 serial; 646 int ret; 647 648 _enter("{%d}", conn->debug_id); 649 650 get_random_bytes(&conn->rxkad.nonce, sizeof(conn->rxkad.nonce)); 651 652 challenge.version = htonl(2); 653 challenge.nonce = htonl(conn->rxkad.nonce); 654 challenge.min_level = htonl(0); 655 challenge.__padding = 0; 656 657 msg.msg_name = &conn->peer->srx.transport; 658 msg.msg_namelen = conn->peer->srx.transport_len; 659 msg.msg_control = NULL; 660 msg.msg_controllen = 0; 661 msg.msg_flags = 0; 662 663 whdr.epoch = htonl(conn->proto.epoch); 664 whdr.cid = htonl(conn->proto.cid); 665 whdr.callNumber = 0; 666 whdr.seq = 0; 667 whdr.type = RXRPC_PACKET_TYPE_CHALLENGE; 668 whdr.flags = conn->out_clientflag; 669 whdr.userStatus = 0; 670 whdr.securityIndex = conn->security_ix; 671 whdr._rsvd = 0; 672 whdr.serviceId = htons(conn->service_id); 673 674 iov[0].iov_base = &whdr; 675 iov[0].iov_len = sizeof(whdr); 676 iov[1].iov_base = &challenge; 677 iov[1].iov_len = sizeof(challenge); 678 679 len = iov[0].iov_len + iov[1].iov_len; 680 681 serial = rxrpc_get_next_serial(conn); 682 whdr.serial = htonl(serial); 683 684 trace_rxrpc_tx_challenge(conn, serial, 0, conn->rxkad.nonce); 685 686 ret = kernel_sendmsg(conn->local->socket, &msg, iov, 2, len); 687 if (ret < 0) { 688 trace_rxrpc_tx_fail(conn->debug_id, serial, ret, 689 rxrpc_tx_point_rxkad_challenge); 690 return -EAGAIN; 691 } 692 693 rxrpc_peer_mark_tx(conn->peer); 694 trace_rxrpc_tx_packet(conn->debug_id, &whdr, 695 rxrpc_tx_point_rxkad_challenge); 696 _leave(" = 0"); 697 return 0; 698 } 699 700 /* 701 * calculate the response checksum 702 */ 703 static void rxkad_calc_response_checksum(struct rxkad_response *response) 704 { 705 u32 csum = 1000003; 706 int loop; 707 u8 *p = (u8 *) response; 708 709 for (loop = sizeof(*response); loop > 0; loop--) 710 csum = csum * 0x10204081 + *p++; 711 712 response->encrypted.checksum = htonl(csum); 713 } 714 715 /* 716 * encrypt the response packet 717 */ 718 static int rxkad_encrypt_response(struct rxrpc_connection *conn, 719 struct sk_buff *response, 720 const struct rxkad_key *s2) 721 { 722 struct skcipher_request *req; 723 struct rxrpc_crypt iv; 724 struct scatterlist sg[1]; 725 size_t encsize = sizeof(((struct rxkad_response *)0)->encrypted); 726 int ret; 727 728 sg_init_table(sg, ARRAY_SIZE(sg)); 729 ret = skb_to_sgvec(response, sg, 730 sizeof(struct rxrpc_wire_header) + 731 offsetof(struct rxkad_response, encrypted), encsize); 732 if (ret < 0) 733 return ret; 734 735 req = skcipher_request_alloc(&conn->rxkad.cipher->base, GFP_NOFS); 736 if (!req) 737 return -ENOMEM; 738 739 /* continue encrypting from where we left off */ 740 memcpy(&iv, s2->session_key, sizeof(iv)); 741 742 skcipher_request_set_sync_tfm(req, conn->rxkad.cipher); 743 skcipher_request_set_callback(req, 0, NULL, NULL); 744 skcipher_request_set_crypt(req, sg, sg, encsize, iv.x); 745 ret = crypto_skcipher_encrypt(req); 746 skcipher_request_free(req); 747 return ret; 748 } 749 750 /* 751 * Validate a challenge packet. 752 */ 753 static bool rxkad_validate_challenge(struct rxrpc_connection *conn, 754 struct sk_buff *skb) 755 { 756 struct rxkad_challenge challenge; 757 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 758 u32 version, min_level; 759 int ret; 760 761 _enter("{%d,%x}", conn->debug_id, key_serial(conn->key)); 762 763 if (!conn->key) { 764 rxrpc_abort_conn(conn, skb, RX_PROTOCOL_ERROR, -EPROTO, 765 rxkad_abort_chall_no_key); 766 return false; 767 } 768 769 ret = key_validate(conn->key); 770 if (ret < 0) { 771 rxrpc_abort_conn(conn, skb, RXKADEXPIRED, ret, 772 rxkad_abort_chall_key_expired); 773 return false; 774 } 775 776 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header), 777 &challenge, sizeof(challenge)) < 0) { 778 rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO, 779 rxkad_abort_chall_short); 780 return false; 781 } 782 783 version = ntohl(challenge.version); 784 sp->chall.rxkad_nonce = ntohl(challenge.nonce); 785 min_level = ntohl(challenge.min_level); 786 787 trace_rxrpc_rx_challenge(conn, sp->hdr.serial, version, 788 sp->chall.rxkad_nonce, min_level); 789 790 if (version != RXKAD_VERSION) { 791 rxrpc_abort_conn(conn, skb, RXKADINCONSISTENCY, -EPROTO, 792 rxkad_abort_chall_version); 793 return false; 794 } 795 796 if (conn->security_level < min_level) { 797 rxrpc_abort_conn(conn, skb, RXKADLEVELFAIL, -EACCES, 798 rxkad_abort_chall_level); 799 return false; 800 } 801 return true; 802 } 803 804 /* 805 * Insert the header into the response. 806 */ 807 static noinline 808 int rxkad_insert_response_header(struct rxrpc_connection *conn, 809 const struct rxrpc_key_token *token, 810 struct sk_buff *challenge, 811 struct sk_buff *response, 812 size_t *offset) 813 { 814 struct rxrpc_skb_priv *csp = rxrpc_skb(challenge); 815 struct { 816 struct rxrpc_wire_header whdr; 817 struct rxkad_response resp; 818 } h; 819 int ret; 820 821 h.whdr.epoch = htonl(conn->proto.epoch); 822 h.whdr.cid = htonl(conn->proto.cid); 823 h.whdr.callNumber = 0; 824 h.whdr.serial = 0; 825 h.whdr.seq = 0; 826 h.whdr.type = RXRPC_PACKET_TYPE_RESPONSE; 827 h.whdr.flags = conn->out_clientflag; 828 h.whdr.userStatus = 0; 829 h.whdr.securityIndex = conn->security_ix; 830 h.whdr.cksum = 0; 831 h.whdr.serviceId = htons(conn->service_id); 832 h.resp.version = htonl(RXKAD_VERSION); 833 h.resp.__pad = 0; 834 h.resp.encrypted.epoch = htonl(conn->proto.epoch); 835 h.resp.encrypted.cid = htonl(conn->proto.cid); 836 h.resp.encrypted.checksum = 0; 837 h.resp.encrypted.securityIndex = htonl(conn->security_ix); 838 h.resp.encrypted.call_id[0] = htonl(conn->channels[0].call_counter); 839 h.resp.encrypted.call_id[1] = htonl(conn->channels[1].call_counter); 840 h.resp.encrypted.call_id[2] = htonl(conn->channels[2].call_counter); 841 h.resp.encrypted.call_id[3] = htonl(conn->channels[3].call_counter); 842 h.resp.encrypted.inc_nonce = htonl(csp->chall.rxkad_nonce + 1); 843 h.resp.encrypted.level = htonl(conn->security_level); 844 h.resp.kvno = htonl(token->kad->kvno); 845 h.resp.ticket_len = htonl(token->kad->ticket_len); 846 847 rxkad_calc_response_checksum(&h.resp); 848 849 ret = skb_store_bits(response, *offset, &h, sizeof(h)); 850 *offset += sizeof(h); 851 return ret; 852 } 853 854 /* 855 * respond to a challenge packet 856 */ 857 static int rxkad_respond_to_challenge(struct rxrpc_connection *conn, 858 struct sk_buff *challenge) 859 { 860 const struct rxrpc_key_token *token; 861 struct rxrpc_skb_priv *csp, *rsp; 862 struct sk_buff *response; 863 size_t len, offset = 0; 864 int ret = -EPROTO; 865 866 _enter("{%d,%x}", conn->debug_id, key_serial(conn->key)); 867 868 ret = key_validate(conn->key); 869 if (ret < 0) 870 return rxrpc_abort_conn(conn, challenge, RXKADEXPIRED, ret, 871 rxkad_abort_chall_key_expired); 872 873 token = conn->key->payload.data[0]; 874 875 /* build the response packet */ 876 len = sizeof(struct rxrpc_wire_header) + 877 sizeof(struct rxkad_response) + 878 token->kad->ticket_len; 879 880 response = alloc_skb_with_frags(0, len, 0, &ret, GFP_NOFS); 881 if (!response) 882 goto error; 883 rxrpc_new_skb(response, rxrpc_skb_new_response_rxkad); 884 response->len = len; 885 response->data_len = len; 886 887 offset = 0; 888 ret = rxkad_insert_response_header(conn, token, challenge, response, 889 &offset); 890 if (ret < 0) 891 goto error; 892 893 ret = rxkad_encrypt_response(conn, response, token->kad); 894 if (ret < 0) 895 goto error; 896 897 ret = skb_store_bits(response, offset, token->kad->ticket, 898 token->kad->ticket_len); 899 if (ret < 0) 900 goto error; 901 902 csp = rxrpc_skb(challenge); 903 rsp = rxrpc_skb(response); 904 rsp->resp.len = len; 905 rsp->resp.challenge_serial = csp->hdr.serial; 906 rxrpc_post_response(conn, response); 907 response = NULL; 908 ret = 0; 909 910 error: 911 rxrpc_free_skb(response, rxrpc_skb_put_response); 912 return ret; 913 } 914 915 /* 916 * RxKAD does automatic response only as there's nothing to manage that isn't 917 * already in the key. 918 */ 919 static int rxkad_sendmsg_respond_to_challenge(struct sk_buff *challenge, 920 struct msghdr *msg) 921 { 922 return -EINVAL; 923 } 924 925 /** 926 * rxkad_kernel_respond_to_challenge - Respond to a challenge with appdata 927 * @challenge: The challenge to respond to 928 * 929 * Allow a kernel application to respond to a CHALLENGE. 930 * 931 * Return: %0 if successful and a negative error code otherwise. 932 */ 933 int rxkad_kernel_respond_to_challenge(struct sk_buff *challenge) 934 { 935 struct rxrpc_skb_priv *csp = rxrpc_skb(challenge); 936 937 return rxkad_respond_to_challenge(csp->chall.conn, challenge); 938 } 939 EXPORT_SYMBOL(rxkad_kernel_respond_to_challenge); 940 941 /* 942 * decrypt the kerberos IV ticket in the response 943 */ 944 static int rxkad_decrypt_ticket(struct rxrpc_connection *conn, 945 struct key *server_key, 946 struct sk_buff *skb, 947 void *ticket, size_t ticket_len, 948 struct rxrpc_crypt *_session_key, 949 time64_t *_expiry) 950 { 951 struct skcipher_request *req; 952 struct rxrpc_crypt iv, key; 953 struct scatterlist sg[1]; 954 struct in_addr addr; 955 unsigned int life; 956 time64_t issue, now; 957 int ret; 958 bool little_endian; 959 u8 *p, *q, *name, *end; 960 961 _enter("{%d},{%x}", conn->debug_id, key_serial(server_key)); 962 963 *_expiry = 0; 964 965 ASSERT(server_key->payload.data[0] != NULL); 966 967 memcpy(&iv, &server_key->payload.data[2], sizeof(iv)); 968 969 req = skcipher_request_alloc(server_key->payload.data[0], GFP_NOFS); 970 if (!req) 971 return -ENOMEM; 972 973 sg_init_one(&sg[0], ticket, ticket_len); 974 skcipher_request_set_callback(req, 0, NULL, NULL); 975 skcipher_request_set_crypt(req, sg, sg, ticket_len, iv.x); 976 ret = crypto_skcipher_decrypt(req); 977 skcipher_request_free(req); 978 if (ret < 0) 979 return rxrpc_abort_conn(conn, skb, RXKADBADTICKET, -EPROTO, 980 rxkad_abort_resp_tkt_short); 981 982 p = ticket; 983 end = p + ticket_len; 984 985 #define Z(field, fieldl) \ 986 ({ \ 987 u8 *__str = p; \ 988 q = memchr(p, 0, end - p); \ 989 if (!q || q - p > field##_SZ) \ 990 return rxrpc_abort_conn( \ 991 conn, skb, RXKADBADTICKET, -EPROTO, \ 992 rxkad_abort_resp_tkt_##fieldl); \ 993 for (; p < q; p++) \ 994 if (!isprint(*p)) \ 995 return rxrpc_abort_conn( \ 996 conn, skb, RXKADBADTICKET, -EPROTO, \ 997 rxkad_abort_resp_tkt_##fieldl); \ 998 p++; \ 999 __str; \ 1000 }) 1001 1002 /* extract the ticket flags */ 1003 _debug("KIV FLAGS: %x", *p); 1004 little_endian = *p & 1; 1005 p++; 1006 1007 /* extract the authentication name */ 1008 name = Z(ANAME, aname); 1009 _debug("KIV ANAME: %s", name); 1010 1011 /* extract the principal's instance */ 1012 name = Z(INST, inst); 1013 _debug("KIV INST : %s", name); 1014 1015 /* extract the principal's authentication domain */ 1016 name = Z(REALM, realm); 1017 _debug("KIV REALM: %s", name); 1018 1019 if (end - p < 4 + 8 + 4 + 2) 1020 return rxrpc_abort_conn(conn, skb, RXKADBADTICKET, -EPROTO, 1021 rxkad_abort_resp_tkt_short); 1022 1023 /* get the IPv4 address of the entity that requested the ticket */ 1024 memcpy(&addr, p, sizeof(addr)); 1025 p += 4; 1026 _debug("KIV ADDR : %pI4", &addr); 1027 1028 /* get the session key from the ticket */ 1029 memcpy(&key, p, sizeof(key)); 1030 p += 8; 1031 _debug("KIV KEY : %08x %08x", ntohl(key.n[0]), ntohl(key.n[1])); 1032 memcpy(_session_key, &key, sizeof(key)); 1033 1034 /* get the ticket's lifetime */ 1035 life = *p++ * 5 * 60; 1036 _debug("KIV LIFE : %u", life); 1037 1038 /* get the issue time of the ticket */ 1039 if (little_endian) { 1040 __le32 stamp; 1041 memcpy(&stamp, p, 4); 1042 issue = rxrpc_u32_to_time64(le32_to_cpu(stamp)); 1043 } else { 1044 __be32 stamp; 1045 memcpy(&stamp, p, 4); 1046 issue = rxrpc_u32_to_time64(be32_to_cpu(stamp)); 1047 } 1048 p += 4; 1049 now = ktime_get_real_seconds(); 1050 _debug("KIV ISSUE: %llx [%llx]", issue, now); 1051 1052 /* check the ticket is in date */ 1053 if (issue > now) 1054 return rxrpc_abort_conn(conn, skb, RXKADNOAUTH, -EKEYREJECTED, 1055 rxkad_abort_resp_tkt_future); 1056 if (issue < now - life) 1057 return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, -EKEYEXPIRED, 1058 rxkad_abort_resp_tkt_expired); 1059 1060 *_expiry = issue + life; 1061 1062 /* get the service name */ 1063 name = Z(SNAME, sname); 1064 _debug("KIV SNAME: %s", name); 1065 1066 /* get the service instance name */ 1067 name = Z(INST, sinst); 1068 _debug("KIV SINST: %s", name); 1069 return 0; 1070 } 1071 1072 /* 1073 * decrypt the response packet 1074 */ 1075 static int rxkad_decrypt_response(struct rxrpc_connection *conn, 1076 struct rxkad_response *resp, 1077 const struct rxrpc_crypt *session_key) 1078 { 1079 struct skcipher_request *req = rxkad_ci_req; 1080 struct scatterlist sg[1]; 1081 struct rxrpc_crypt iv; 1082 int ret; 1083 1084 _enter(",,%08x%08x", 1085 ntohl(session_key->n[0]), ntohl(session_key->n[1])); 1086 1087 mutex_lock(&rxkad_ci_mutex); 1088 ret = crypto_sync_skcipher_setkey(rxkad_ci, session_key->x, 1089 sizeof(*session_key)); 1090 if (ret < 0) 1091 goto unlock; 1092 1093 memcpy(&iv, session_key, sizeof(iv)); 1094 1095 sg_init_table(sg, 1); 1096 sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted)); 1097 skcipher_request_set_sync_tfm(req, rxkad_ci); 1098 skcipher_request_set_callback(req, 0, NULL, NULL); 1099 skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x); 1100 ret = crypto_skcipher_decrypt(req); 1101 skcipher_request_zero(req); 1102 1103 unlock: 1104 mutex_unlock(&rxkad_ci_mutex); 1105 1106 _leave(""); 1107 return ret; 1108 } 1109 1110 /* 1111 * verify a response 1112 */ 1113 static int rxkad_verify_response(struct rxrpc_connection *conn, 1114 struct sk_buff *skb, 1115 void *buffer, unsigned int len) 1116 { 1117 struct rxkad_response *response; 1118 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 1119 struct rxrpc_crypt session_key; 1120 struct key *server_key; 1121 time64_t expiry; 1122 void *ticket; 1123 u32 version, kvno, ticket_len, level; 1124 __be32 csum; 1125 int ret, i; 1126 1127 _enter("{%d}", conn->debug_id); 1128 1129 server_key = rxrpc_look_up_server_security(conn, skb, 0, 0); 1130 if (IS_ERR(server_key)) { 1131 ret = PTR_ERR(server_key); 1132 switch (ret) { 1133 case -ENOKEY: 1134 return rxrpc_abort_conn(conn, skb, RXKADUNKNOWNKEY, ret, 1135 rxkad_abort_resp_nokey); 1136 case -EKEYEXPIRED: 1137 return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, ret, 1138 rxkad_abort_resp_key_expired); 1139 default: 1140 return rxrpc_abort_conn(conn, skb, RXKADNOAUTH, ret, 1141 rxkad_abort_resp_key_rejected); 1142 } 1143 } 1144 1145 response = buffer; 1146 if (len < sizeof(*response)) { 1147 ret = rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO, 1148 rxkad_abort_resp_short); 1149 goto error; 1150 } 1151 1152 version = ntohl(response->version); 1153 ticket_len = ntohl(response->ticket_len); 1154 kvno = ntohl(response->kvno); 1155 1156 trace_rxrpc_rx_response(conn, sp->hdr.serial, version, kvno, ticket_len); 1157 1158 buffer += sizeof(*response); 1159 len -= sizeof(*response); 1160 1161 if (version != RXKAD_VERSION) { 1162 ret = rxrpc_abort_conn(conn, skb, RXKADINCONSISTENCY, -EPROTO, 1163 rxkad_abort_resp_version); 1164 goto error; 1165 } 1166 1167 if (ticket_len < 4 || ticket_len > MAXKRB5TICKETLEN) { 1168 ret = rxrpc_abort_conn(conn, skb, RXKADTICKETLEN, -EPROTO, 1169 rxkad_abort_resp_tkt_len); 1170 goto error; 1171 } 1172 1173 if (kvno >= RXKAD_TKT_TYPE_KERBEROS_V5) { 1174 ret = rxrpc_abort_conn(conn, skb, RXKADUNKNOWNKEY, -EPROTO, 1175 rxkad_abort_resp_unknown_tkt); 1176 goto error; 1177 } 1178 1179 /* extract the kerberos ticket and decrypt and decode it */ 1180 ticket = buffer; 1181 if (ticket_len > len) { 1182 ret = rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO, 1183 rxkad_abort_resp_short_tkt); 1184 goto error; 1185 } 1186 1187 ret = rxkad_decrypt_ticket(conn, server_key, skb, ticket, ticket_len, 1188 &session_key, &expiry); 1189 if (ret < 0) 1190 goto error; 1191 1192 /* use the session key from inside the ticket to decrypt the 1193 * response */ 1194 ret = rxkad_decrypt_response(conn, response, &session_key); 1195 if (ret < 0) 1196 goto error; 1197 1198 if (ntohl(response->encrypted.epoch) != conn->proto.epoch || 1199 ntohl(response->encrypted.cid) != conn->proto.cid || 1200 ntohl(response->encrypted.securityIndex) != conn->security_ix) { 1201 ret = rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO, 1202 rxkad_abort_resp_bad_param); 1203 goto error; 1204 } 1205 1206 csum = response->encrypted.checksum; 1207 response->encrypted.checksum = 0; 1208 rxkad_calc_response_checksum(response); 1209 if (response->encrypted.checksum != csum) { 1210 ret = rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO, 1211 rxkad_abort_resp_bad_checksum); 1212 goto error; 1213 } 1214 1215 for (i = 0; i < RXRPC_MAXCALLS; i++) { 1216 u32 call_id = ntohl(response->encrypted.call_id[i]); 1217 u32 counter = READ_ONCE(conn->channels[i].call_counter); 1218 1219 if (call_id > INT_MAX) { 1220 ret = rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO, 1221 rxkad_abort_resp_bad_callid); 1222 goto error; 1223 } 1224 1225 if (call_id < counter) { 1226 ret = rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO, 1227 rxkad_abort_resp_call_ctr); 1228 goto error; 1229 } 1230 1231 if (call_id > counter) { 1232 if (conn->channels[i].call) { 1233 ret = rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO, 1234 rxkad_abort_resp_call_state); 1235 goto error; 1236 } 1237 conn->channels[i].call_counter = call_id; 1238 } 1239 } 1240 1241 if (ntohl(response->encrypted.inc_nonce) != conn->rxkad.nonce + 1) { 1242 ret = rxrpc_abort_conn(conn, skb, RXKADOUTOFSEQUENCE, -EPROTO, 1243 rxkad_abort_resp_ooseq); 1244 goto error; 1245 } 1246 1247 level = ntohl(response->encrypted.level); 1248 if (level > RXRPC_SECURITY_ENCRYPT) { 1249 ret = rxrpc_abort_conn(conn, skb, RXKADLEVELFAIL, -EPROTO, 1250 rxkad_abort_resp_level); 1251 goto error; 1252 } 1253 conn->security_level = level; 1254 1255 /* create a key to hold the security data and expiration time - after 1256 * this the connection security can be handled in exactly the same way 1257 * as for a client connection */ 1258 ret = rxrpc_get_server_data_key(conn, &session_key, expiry, kvno); 1259 1260 error: 1261 key_put(server_key); 1262 _leave(" = %d", ret); 1263 return ret; 1264 } 1265 1266 /* 1267 * clear the connection security 1268 */ 1269 static void rxkad_clear(struct rxrpc_connection *conn) 1270 { 1271 _enter(""); 1272 1273 if (conn->rxkad.cipher) 1274 crypto_free_sync_skcipher(conn->rxkad.cipher); 1275 } 1276 1277 /* 1278 * Initialise the rxkad security service. 1279 */ 1280 static int rxkad_init(void) 1281 { 1282 struct crypto_sync_skcipher *tfm; 1283 struct skcipher_request *req; 1284 1285 /* pin the cipher we need so that the crypto layer doesn't invoke 1286 * keventd to go get it */ 1287 tfm = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0); 1288 if (IS_ERR(tfm)) 1289 return PTR_ERR(tfm); 1290 1291 req = skcipher_request_alloc(&tfm->base, GFP_KERNEL); 1292 if (!req) 1293 goto nomem_tfm; 1294 1295 rxkad_ci_req = req; 1296 rxkad_ci = tfm; 1297 return 0; 1298 1299 nomem_tfm: 1300 crypto_free_sync_skcipher(tfm); 1301 return -ENOMEM; 1302 } 1303 1304 /* 1305 * Clean up the rxkad security service. 1306 */ 1307 static void rxkad_exit(void) 1308 { 1309 crypto_free_sync_skcipher(rxkad_ci); 1310 skcipher_request_free(rxkad_ci_req); 1311 } 1312 1313 /* 1314 * RxRPC Kerberos-based security 1315 */ 1316 const struct rxrpc_security rxkad = { 1317 .name = "rxkad", 1318 .security_index = RXRPC_SECURITY_RXKAD, 1319 .no_key_abort = RXKADUNKNOWNKEY, 1320 .init = rxkad_init, 1321 .exit = rxkad_exit, 1322 .preparse_server_key = rxkad_preparse_server_key, 1323 .free_preparse_server_key = rxkad_free_preparse_server_key, 1324 .destroy_server_key = rxkad_destroy_server_key, 1325 .init_connection_security = rxkad_init_connection_security, 1326 .alloc_txbuf = rxkad_alloc_txbuf, 1327 .secure_packet = rxkad_secure_packet, 1328 .verify_packet = rxkad_verify_packet, 1329 .free_call_crypto = rxkad_free_call_crypto, 1330 .issue_challenge = rxkad_issue_challenge, 1331 .validate_challenge = rxkad_validate_challenge, 1332 .sendmsg_respond_to_challenge = rxkad_sendmsg_respond_to_challenge, 1333 .respond_to_challenge = rxkad_respond_to_challenge, 1334 .verify_response = rxkad_verify_response, 1335 .clear = rxkad_clear, 1336 }; 1337