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->params.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->params.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 int rxkad_how_much_data(struct rxrpc_call *call, size_t remain, 149 size_t *_buf_size, size_t *_data_size, size_t *_offset) 150 { 151 size_t shdr, buf_size, chunk; 152 153 switch (call->conn->params.security_level) { 154 default: 155 buf_size = chunk = min_t(size_t, remain, RXRPC_JUMBO_DATALEN); 156 shdr = 0; 157 goto out; 158 case RXRPC_SECURITY_AUTH: 159 shdr = sizeof(struct rxkad_level1_hdr); 160 break; 161 case RXRPC_SECURITY_ENCRYPT: 162 shdr = sizeof(struct rxkad_level2_hdr); 163 break; 164 } 165 166 buf_size = round_down(RXRPC_JUMBO_DATALEN, RXKAD_ALIGN); 167 168 chunk = buf_size - shdr; 169 if (remain < chunk) 170 buf_size = round_up(shdr + remain, RXKAD_ALIGN); 171 172 out: 173 *_buf_size = buf_size; 174 *_data_size = chunk; 175 *_offset = shdr; 176 return 0; 177 } 178 179 /* 180 * prime the encryption state with the invariant parts of a connection's 181 * description 182 */ 183 static int rxkad_prime_packet_security(struct rxrpc_connection *conn, 184 struct crypto_sync_skcipher *ci) 185 { 186 struct skcipher_request *req; 187 struct rxrpc_key_token *token; 188 struct scatterlist sg; 189 struct rxrpc_crypt iv; 190 __be32 *tmpbuf; 191 size_t tmpsize = 4 * sizeof(__be32); 192 193 _enter(""); 194 195 if (!conn->params.key) 196 return 0; 197 198 tmpbuf = kmalloc(tmpsize, GFP_KERNEL); 199 if (!tmpbuf) 200 return -ENOMEM; 201 202 req = skcipher_request_alloc(&ci->base, GFP_NOFS); 203 if (!req) { 204 kfree(tmpbuf); 205 return -ENOMEM; 206 } 207 208 token = conn->params.key->payload.data[0]; 209 memcpy(&iv, token->kad->session_key, sizeof(iv)); 210 211 tmpbuf[0] = htonl(conn->proto.epoch); 212 tmpbuf[1] = htonl(conn->proto.cid); 213 tmpbuf[2] = 0; 214 tmpbuf[3] = htonl(conn->security_ix); 215 216 sg_init_one(&sg, tmpbuf, tmpsize); 217 skcipher_request_set_sync_tfm(req, ci); 218 skcipher_request_set_callback(req, 0, NULL, NULL); 219 skcipher_request_set_crypt(req, &sg, &sg, tmpsize, iv.x); 220 crypto_skcipher_encrypt(req); 221 skcipher_request_free(req); 222 223 memcpy(&conn->rxkad.csum_iv, tmpbuf + 2, sizeof(conn->rxkad.csum_iv)); 224 kfree(tmpbuf); 225 _leave(" = 0"); 226 return 0; 227 } 228 229 /* 230 * Allocate and prepare the crypto request on a call. For any particular call, 231 * this is called serially for the packets, so no lock should be necessary. 232 */ 233 static struct skcipher_request *rxkad_get_call_crypto(struct rxrpc_call *call) 234 { 235 struct crypto_skcipher *tfm = &call->conn->rxkad.cipher->base; 236 237 return skcipher_request_alloc(tfm, GFP_NOFS); 238 } 239 240 /* 241 * Clean up the crypto on a call. 242 */ 243 static void rxkad_free_call_crypto(struct rxrpc_call *call) 244 { 245 } 246 247 /* 248 * partially encrypt a packet (level 1 security) 249 */ 250 static int rxkad_secure_packet_auth(const struct rxrpc_call *call, 251 struct rxrpc_txbuf *txb, 252 struct skcipher_request *req) 253 { 254 struct rxkad_level1_hdr *hdr = (void *)txb->data; 255 struct rxrpc_crypt iv; 256 struct scatterlist sg; 257 size_t pad; 258 u16 check; 259 260 _enter(""); 261 262 check = txb->seq ^ ntohl(txb->wire.callNumber); 263 hdr->data_size = htonl((u32)check << 16 | txb->len); 264 265 txb->len += sizeof(struct rxkad_level1_hdr); 266 pad = txb->len; 267 pad = RXKAD_ALIGN - pad; 268 pad &= RXKAD_ALIGN - 1; 269 if (pad) { 270 memset(txb->data + txb->offset, 0, pad); 271 txb->len += pad; 272 } 273 274 /* start the encryption afresh */ 275 memset(&iv, 0, sizeof(iv)); 276 277 sg_init_one(&sg, txb->data, 8); 278 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 279 skcipher_request_set_callback(req, 0, NULL, NULL); 280 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x); 281 crypto_skcipher_encrypt(req); 282 skcipher_request_zero(req); 283 284 _leave(" = 0"); 285 return 0; 286 } 287 288 /* 289 * wholly encrypt a packet (level 2 security) 290 */ 291 static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call, 292 struct rxrpc_txbuf *txb, 293 struct skcipher_request *req) 294 { 295 const struct rxrpc_key_token *token; 296 struct rxkad_level2_hdr *rxkhdr = (void *)txb->data; 297 struct rxrpc_crypt iv; 298 struct scatterlist sg; 299 size_t pad; 300 u16 check; 301 int ret; 302 303 _enter(""); 304 305 check = txb->seq ^ ntohl(txb->wire.callNumber); 306 307 rxkhdr->data_size = htonl(txb->len | (u32)check << 16); 308 rxkhdr->checksum = 0; 309 310 txb->len += sizeof(struct rxkad_level2_hdr); 311 pad = txb->len; 312 pad = RXKAD_ALIGN - pad; 313 pad &= RXKAD_ALIGN - 1; 314 if (pad) { 315 memset(txb->data + txb->offset, 0, pad); 316 txb->len += pad; 317 } 318 319 /* encrypt from the session key */ 320 token = call->conn->params.key->payload.data[0]; 321 memcpy(&iv, token->kad->session_key, sizeof(iv)); 322 323 sg_init_one(&sg, txb->data, txb->len); 324 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 325 skcipher_request_set_callback(req, 0, NULL, NULL); 326 skcipher_request_set_crypt(req, &sg, &sg, txb->len, iv.x); 327 ret = crypto_skcipher_encrypt(req); 328 skcipher_request_zero(req); 329 return ret; 330 } 331 332 /* 333 * checksum an RxRPC packet header 334 */ 335 static int rxkad_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb) 336 { 337 struct skcipher_request *req; 338 struct rxrpc_crypt iv; 339 struct scatterlist sg; 340 union { 341 __be32 buf[2]; 342 } crypto __aligned(8); 343 u32 x, y; 344 int ret; 345 346 _enter("{%d{%x}},{#%u},%u,", 347 call->debug_id, key_serial(call->conn->params.key), 348 txb->seq, txb->len); 349 350 if (!call->conn->rxkad.cipher) 351 return 0; 352 353 ret = key_validate(call->conn->params.key); 354 if (ret < 0) 355 return ret; 356 357 req = rxkad_get_call_crypto(call); 358 if (!req) 359 return -ENOMEM; 360 361 /* continue encrypting from where we left off */ 362 memcpy(&iv, call->conn->rxkad.csum_iv.x, sizeof(iv)); 363 364 /* calculate the security checksum */ 365 x = (ntohl(txb->wire.cid) & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT); 366 x |= txb->seq & 0x3fffffff; 367 crypto.buf[0] = txb->wire.callNumber; 368 crypto.buf[1] = htonl(x); 369 370 sg_init_one(&sg, crypto.buf, 8); 371 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 372 skcipher_request_set_callback(req, 0, NULL, NULL); 373 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x); 374 crypto_skcipher_encrypt(req); 375 skcipher_request_zero(req); 376 377 y = ntohl(crypto.buf[1]); 378 y = (y >> 16) & 0xffff; 379 if (y == 0) 380 y = 1; /* zero checksums are not permitted */ 381 txb->wire.cksum = htons(y); 382 383 switch (call->conn->params.security_level) { 384 case RXRPC_SECURITY_PLAIN: 385 ret = 0; 386 break; 387 case RXRPC_SECURITY_AUTH: 388 ret = rxkad_secure_packet_auth(call, txb, req); 389 break; 390 case RXRPC_SECURITY_ENCRYPT: 391 ret = rxkad_secure_packet_encrypt(call, txb, req); 392 break; 393 default: 394 ret = -EPERM; 395 break; 396 } 397 398 skcipher_request_free(req); 399 _leave(" = %d [set %x]", ret, y); 400 return ret; 401 } 402 403 /* 404 * decrypt partial encryption on a packet (level 1 security) 405 */ 406 static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb, 407 rxrpc_seq_t seq, 408 struct skcipher_request *req) 409 { 410 struct rxkad_level1_hdr sechdr; 411 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 412 struct rxrpc_crypt iv; 413 struct scatterlist sg[16]; 414 bool aborted; 415 u32 data_size, buf; 416 u16 check; 417 int ret; 418 419 _enter(""); 420 421 if (sp->len < 8) { 422 aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_hdr", "V1H", 423 RXKADSEALEDINCON); 424 goto protocol_error; 425 } 426 427 /* Decrypt the skbuff in-place. TODO: We really want to decrypt 428 * directly into the target buffer. 429 */ 430 sg_init_table(sg, ARRAY_SIZE(sg)); 431 ret = skb_to_sgvec(skb, sg, sp->offset, 8); 432 if (unlikely(ret < 0)) 433 return ret; 434 435 /* start the decryption afresh */ 436 memset(&iv, 0, sizeof(iv)); 437 438 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 439 skcipher_request_set_callback(req, 0, NULL, NULL); 440 skcipher_request_set_crypt(req, sg, sg, 8, iv.x); 441 crypto_skcipher_decrypt(req); 442 skcipher_request_zero(req); 443 444 /* Extract the decrypted packet length */ 445 if (skb_copy_bits(skb, sp->offset, &sechdr, sizeof(sechdr)) < 0) { 446 aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_len", "XV1", 447 RXKADDATALEN); 448 goto protocol_error; 449 } 450 sp->offset += sizeof(sechdr); 451 sp->len -= sizeof(sechdr); 452 453 buf = ntohl(sechdr.data_size); 454 data_size = buf & 0xffff; 455 456 check = buf >> 16; 457 check ^= seq ^ call->call_id; 458 check &= 0xffff; 459 if (check != 0) { 460 aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_check", "V1C", 461 RXKADSEALEDINCON); 462 goto protocol_error; 463 } 464 465 if (data_size > sp->len) { 466 aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_datalen", "V1L", 467 RXKADDATALEN); 468 goto protocol_error; 469 } 470 sp->len = data_size; 471 472 _leave(" = 0 [dlen=%x]", data_size); 473 return 0; 474 475 protocol_error: 476 if (aborted) 477 rxrpc_send_abort_packet(call); 478 return -EPROTO; 479 } 480 481 /* 482 * wholly decrypt a packet (level 2 security) 483 */ 484 static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb, 485 rxrpc_seq_t seq, 486 struct skcipher_request *req) 487 { 488 const struct rxrpc_key_token *token; 489 struct rxkad_level2_hdr sechdr; 490 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 491 struct rxrpc_crypt iv; 492 struct scatterlist _sg[4], *sg; 493 bool aborted; 494 u32 data_size, buf; 495 u16 check; 496 int nsg, ret; 497 498 _enter(",{%d}", sp->len); 499 500 if (sp->len < 8) { 501 aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_hdr", "V2H", 502 RXKADSEALEDINCON); 503 goto protocol_error; 504 } 505 506 /* Decrypt the skbuff in-place. TODO: We really want to decrypt 507 * directly into the target buffer. 508 */ 509 sg = _sg; 510 nsg = skb_shinfo(skb)->nr_frags + 1; 511 if (nsg <= 4) { 512 nsg = 4; 513 } else { 514 sg = kmalloc_array(nsg, sizeof(*sg), GFP_NOIO); 515 if (!sg) 516 goto nomem; 517 } 518 519 sg_init_table(sg, nsg); 520 ret = skb_to_sgvec(skb, sg, sp->offset, sp->len); 521 if (unlikely(ret < 0)) { 522 if (sg != _sg) 523 kfree(sg); 524 return ret; 525 } 526 527 /* decrypt from the session key */ 528 token = call->conn->params.key->payload.data[0]; 529 memcpy(&iv, token->kad->session_key, sizeof(iv)); 530 531 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 532 skcipher_request_set_callback(req, 0, NULL, NULL); 533 skcipher_request_set_crypt(req, sg, sg, sp->len, iv.x); 534 crypto_skcipher_decrypt(req); 535 skcipher_request_zero(req); 536 if (sg != _sg) 537 kfree(sg); 538 539 /* Extract the decrypted packet length */ 540 if (skb_copy_bits(skb, sp->offset, &sechdr, sizeof(sechdr)) < 0) { 541 aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_len", "XV2", 542 RXKADDATALEN); 543 goto protocol_error; 544 } 545 sp->offset += sizeof(sechdr); 546 sp->len -= sizeof(sechdr); 547 548 buf = ntohl(sechdr.data_size); 549 data_size = buf & 0xffff; 550 551 check = buf >> 16; 552 check ^= seq ^ call->call_id; 553 check &= 0xffff; 554 if (check != 0) { 555 aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_check", "V2C", 556 RXKADSEALEDINCON); 557 goto protocol_error; 558 } 559 560 if (data_size > sp->len) { 561 aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_datalen", "V2L", 562 RXKADDATALEN); 563 goto protocol_error; 564 } 565 566 sp->len = data_size; 567 _leave(" = 0 [dlen=%x]", data_size); 568 return 0; 569 570 protocol_error: 571 if (aborted) 572 rxrpc_send_abort_packet(call); 573 return -EPROTO; 574 575 nomem: 576 _leave(" = -ENOMEM"); 577 return -ENOMEM; 578 } 579 580 /* 581 * Verify the security on a received packet and the subpackets therein. 582 */ 583 static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb) 584 { 585 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 586 struct skcipher_request *req; 587 struct rxrpc_crypt iv; 588 struct scatterlist sg; 589 union { 590 __be32 buf[2]; 591 } crypto __aligned(8); 592 rxrpc_seq_t seq = sp->hdr.seq; 593 bool aborted; 594 int ret; 595 u16 cksum; 596 u32 x, y; 597 598 _enter("{%d{%x}},{#%u}", 599 call->debug_id, key_serial(call->conn->params.key), seq); 600 601 if (!call->conn->rxkad.cipher) 602 return 0; 603 604 req = rxkad_get_call_crypto(call); 605 if (!req) 606 return -ENOMEM; 607 608 /* continue encrypting from where we left off */ 609 memcpy(&iv, call->conn->rxkad.csum_iv.x, sizeof(iv)); 610 611 /* validate the security checksum */ 612 x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT); 613 x |= seq & 0x3fffffff; 614 crypto.buf[0] = htonl(call->call_id); 615 crypto.buf[1] = htonl(x); 616 617 sg_init_one(&sg, crypto.buf, 8); 618 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 619 skcipher_request_set_callback(req, 0, NULL, NULL); 620 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x); 621 crypto_skcipher_encrypt(req); 622 skcipher_request_zero(req); 623 624 y = ntohl(crypto.buf[1]); 625 cksum = (y >> 16) & 0xffff; 626 if (cksum == 0) 627 cksum = 1; /* zero checksums are not permitted */ 628 629 if (cksum != sp->hdr.cksum) { 630 aborted = rxrpc_abort_eproto(call, skb, "rxkad_csum", "VCK", 631 RXKADSEALEDINCON); 632 goto protocol_error; 633 } 634 635 switch (call->conn->params.security_level) { 636 case RXRPC_SECURITY_PLAIN: 637 ret = 0; 638 break; 639 case RXRPC_SECURITY_AUTH: 640 ret = rxkad_verify_packet_1(call, skb, seq, req); 641 break; 642 case RXRPC_SECURITY_ENCRYPT: 643 ret = rxkad_verify_packet_2(call, skb, seq, req); 644 break; 645 default: 646 ret = -ENOANO; 647 break; 648 } 649 650 skcipher_request_free(req); 651 return ret; 652 653 protocol_error: 654 if (aborted) 655 rxrpc_send_abort_packet(call); 656 return -EPROTO; 657 } 658 659 /* 660 * issue a challenge 661 */ 662 static int rxkad_issue_challenge(struct rxrpc_connection *conn) 663 { 664 struct rxkad_challenge challenge; 665 struct rxrpc_wire_header whdr; 666 struct msghdr msg; 667 struct kvec iov[2]; 668 size_t len; 669 u32 serial; 670 int ret; 671 672 _enter("{%d}", conn->debug_id); 673 674 get_random_bytes(&conn->rxkad.nonce, sizeof(conn->rxkad.nonce)); 675 676 challenge.version = htonl(2); 677 challenge.nonce = htonl(conn->rxkad.nonce); 678 challenge.min_level = htonl(0); 679 challenge.__padding = 0; 680 681 msg.msg_name = &conn->params.peer->srx.transport; 682 msg.msg_namelen = conn->params.peer->srx.transport_len; 683 msg.msg_control = NULL; 684 msg.msg_controllen = 0; 685 msg.msg_flags = 0; 686 687 whdr.epoch = htonl(conn->proto.epoch); 688 whdr.cid = htonl(conn->proto.cid); 689 whdr.callNumber = 0; 690 whdr.seq = 0; 691 whdr.type = RXRPC_PACKET_TYPE_CHALLENGE; 692 whdr.flags = conn->out_clientflag; 693 whdr.userStatus = 0; 694 whdr.securityIndex = conn->security_ix; 695 whdr._rsvd = 0; 696 whdr.serviceId = htons(conn->service_id); 697 698 iov[0].iov_base = &whdr; 699 iov[0].iov_len = sizeof(whdr); 700 iov[1].iov_base = &challenge; 701 iov[1].iov_len = sizeof(challenge); 702 703 len = iov[0].iov_len + iov[1].iov_len; 704 705 serial = atomic_inc_return(&conn->serial); 706 whdr.serial = htonl(serial); 707 _proto("Tx CHALLENGE %%%u", serial); 708 709 ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 2, len); 710 if (ret < 0) { 711 trace_rxrpc_tx_fail(conn->debug_id, serial, ret, 712 rxrpc_tx_point_rxkad_challenge); 713 return -EAGAIN; 714 } 715 716 conn->params.peer->last_tx_at = ktime_get_seconds(); 717 trace_rxrpc_tx_packet(conn->debug_id, &whdr, 718 rxrpc_tx_point_rxkad_challenge); 719 _leave(" = 0"); 720 return 0; 721 } 722 723 /* 724 * send a Kerberos security response 725 */ 726 static int rxkad_send_response(struct rxrpc_connection *conn, 727 struct rxrpc_host_header *hdr, 728 struct rxkad_response *resp, 729 const struct rxkad_key *s2) 730 { 731 struct rxrpc_wire_header whdr; 732 struct msghdr msg; 733 struct kvec iov[3]; 734 size_t len; 735 u32 serial; 736 int ret; 737 738 _enter(""); 739 740 msg.msg_name = &conn->params.peer->srx.transport; 741 msg.msg_namelen = conn->params.peer->srx.transport_len; 742 msg.msg_control = NULL; 743 msg.msg_controllen = 0; 744 msg.msg_flags = 0; 745 746 memset(&whdr, 0, sizeof(whdr)); 747 whdr.epoch = htonl(hdr->epoch); 748 whdr.cid = htonl(hdr->cid); 749 whdr.type = RXRPC_PACKET_TYPE_RESPONSE; 750 whdr.flags = conn->out_clientflag; 751 whdr.securityIndex = hdr->securityIndex; 752 whdr.serviceId = htons(hdr->serviceId); 753 754 iov[0].iov_base = &whdr; 755 iov[0].iov_len = sizeof(whdr); 756 iov[1].iov_base = resp; 757 iov[1].iov_len = sizeof(*resp); 758 iov[2].iov_base = (void *)s2->ticket; 759 iov[2].iov_len = s2->ticket_len; 760 761 len = iov[0].iov_len + iov[1].iov_len + iov[2].iov_len; 762 763 serial = atomic_inc_return(&conn->serial); 764 whdr.serial = htonl(serial); 765 _proto("Tx RESPONSE %%%u", serial); 766 767 ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 3, len); 768 if (ret < 0) { 769 trace_rxrpc_tx_fail(conn->debug_id, serial, ret, 770 rxrpc_tx_point_rxkad_response); 771 return -EAGAIN; 772 } 773 774 conn->params.peer->last_tx_at = ktime_get_seconds(); 775 _leave(" = 0"); 776 return 0; 777 } 778 779 /* 780 * calculate the response checksum 781 */ 782 static void rxkad_calc_response_checksum(struct rxkad_response *response) 783 { 784 u32 csum = 1000003; 785 int loop; 786 u8 *p = (u8 *) response; 787 788 for (loop = sizeof(*response); loop > 0; loop--) 789 csum = csum * 0x10204081 + *p++; 790 791 response->encrypted.checksum = htonl(csum); 792 } 793 794 /* 795 * encrypt the response packet 796 */ 797 static int rxkad_encrypt_response(struct rxrpc_connection *conn, 798 struct rxkad_response *resp, 799 const struct rxkad_key *s2) 800 { 801 struct skcipher_request *req; 802 struct rxrpc_crypt iv; 803 struct scatterlist sg[1]; 804 805 req = skcipher_request_alloc(&conn->rxkad.cipher->base, GFP_NOFS); 806 if (!req) 807 return -ENOMEM; 808 809 /* continue encrypting from where we left off */ 810 memcpy(&iv, s2->session_key, sizeof(iv)); 811 812 sg_init_table(sg, 1); 813 sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted)); 814 skcipher_request_set_sync_tfm(req, conn->rxkad.cipher); 815 skcipher_request_set_callback(req, 0, NULL, NULL); 816 skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x); 817 crypto_skcipher_encrypt(req); 818 skcipher_request_free(req); 819 return 0; 820 } 821 822 /* 823 * respond to a challenge packet 824 */ 825 static int rxkad_respond_to_challenge(struct rxrpc_connection *conn, 826 struct sk_buff *skb, 827 u32 *_abort_code) 828 { 829 const struct rxrpc_key_token *token; 830 struct rxkad_challenge challenge; 831 struct rxkad_response *resp; 832 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 833 const char *eproto; 834 u32 version, nonce, min_level, abort_code; 835 int ret; 836 837 _enter("{%d,%x}", conn->debug_id, key_serial(conn->params.key)); 838 839 eproto = tracepoint_string("chall_no_key"); 840 abort_code = RX_PROTOCOL_ERROR; 841 if (!conn->params.key) 842 goto protocol_error; 843 844 abort_code = RXKADEXPIRED; 845 ret = key_validate(conn->params.key); 846 if (ret < 0) 847 goto other_error; 848 849 eproto = tracepoint_string("chall_short"); 850 abort_code = RXKADPACKETSHORT; 851 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header), 852 &challenge, sizeof(challenge)) < 0) 853 goto protocol_error; 854 855 version = ntohl(challenge.version); 856 nonce = ntohl(challenge.nonce); 857 min_level = ntohl(challenge.min_level); 858 859 _proto("Rx CHALLENGE %%%u { v=%u n=%u ml=%u }", 860 sp->hdr.serial, version, nonce, min_level); 861 862 eproto = tracepoint_string("chall_ver"); 863 abort_code = RXKADINCONSISTENCY; 864 if (version != RXKAD_VERSION) 865 goto protocol_error; 866 867 abort_code = RXKADLEVELFAIL; 868 ret = -EACCES; 869 if (conn->params.security_level < min_level) 870 goto other_error; 871 872 token = conn->params.key->payload.data[0]; 873 874 /* build the response packet */ 875 resp = kzalloc(sizeof(struct rxkad_response), GFP_NOFS); 876 if (!resp) 877 return -ENOMEM; 878 879 resp->version = htonl(RXKAD_VERSION); 880 resp->encrypted.epoch = htonl(conn->proto.epoch); 881 resp->encrypted.cid = htonl(conn->proto.cid); 882 resp->encrypted.securityIndex = htonl(conn->security_ix); 883 resp->encrypted.inc_nonce = htonl(nonce + 1); 884 resp->encrypted.level = htonl(conn->params.security_level); 885 resp->kvno = htonl(token->kad->kvno); 886 resp->ticket_len = htonl(token->kad->ticket_len); 887 resp->encrypted.call_id[0] = htonl(conn->channels[0].call_counter); 888 resp->encrypted.call_id[1] = htonl(conn->channels[1].call_counter); 889 resp->encrypted.call_id[2] = htonl(conn->channels[2].call_counter); 890 resp->encrypted.call_id[3] = htonl(conn->channels[3].call_counter); 891 892 /* calculate the response checksum and then do the encryption */ 893 rxkad_calc_response_checksum(resp); 894 ret = rxkad_encrypt_response(conn, resp, token->kad); 895 if (ret == 0) 896 ret = rxkad_send_response(conn, &sp->hdr, resp, token->kad); 897 kfree(resp); 898 return ret; 899 900 protocol_error: 901 trace_rxrpc_rx_eproto(NULL, sp->hdr.serial, eproto); 902 ret = -EPROTO; 903 other_error: 904 *_abort_code = abort_code; 905 return ret; 906 } 907 908 /* 909 * decrypt the kerberos IV ticket in the response 910 */ 911 static int rxkad_decrypt_ticket(struct rxrpc_connection *conn, 912 struct key *server_key, 913 struct sk_buff *skb, 914 void *ticket, size_t ticket_len, 915 struct rxrpc_crypt *_session_key, 916 time64_t *_expiry, 917 u32 *_abort_code) 918 { 919 struct skcipher_request *req; 920 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 921 struct rxrpc_crypt iv, key; 922 struct scatterlist sg[1]; 923 struct in_addr addr; 924 unsigned int life; 925 const char *eproto; 926 time64_t issue, now; 927 bool little_endian; 928 int ret; 929 u32 abort_code; 930 u8 *p, *q, *name, *end; 931 932 _enter("{%d},{%x}", conn->debug_id, key_serial(server_key)); 933 934 *_expiry = 0; 935 936 ASSERT(server_key->payload.data[0] != NULL); 937 ASSERTCMP((unsigned long) ticket & 7UL, ==, 0); 938 939 memcpy(&iv, &server_key->payload.data[2], sizeof(iv)); 940 941 ret = -ENOMEM; 942 req = skcipher_request_alloc(server_key->payload.data[0], GFP_NOFS); 943 if (!req) 944 goto temporary_error; 945 946 sg_init_one(&sg[0], ticket, ticket_len); 947 skcipher_request_set_callback(req, 0, NULL, NULL); 948 skcipher_request_set_crypt(req, sg, sg, ticket_len, iv.x); 949 crypto_skcipher_decrypt(req); 950 skcipher_request_free(req); 951 952 p = ticket; 953 end = p + ticket_len; 954 955 #define Z(field) \ 956 ({ \ 957 u8 *__str = p; \ 958 eproto = tracepoint_string("rxkad_bad_"#field); \ 959 q = memchr(p, 0, end - p); \ 960 if (!q || q - p > (field##_SZ)) \ 961 goto bad_ticket; \ 962 for (; p < q; p++) \ 963 if (!isprint(*p)) \ 964 goto bad_ticket; \ 965 p++; \ 966 __str; \ 967 }) 968 969 /* extract the ticket flags */ 970 _debug("KIV FLAGS: %x", *p); 971 little_endian = *p & 1; 972 p++; 973 974 /* extract the authentication name */ 975 name = Z(ANAME); 976 _debug("KIV ANAME: %s", name); 977 978 /* extract the principal's instance */ 979 name = Z(INST); 980 _debug("KIV INST : %s", name); 981 982 /* extract the principal's authentication domain */ 983 name = Z(REALM); 984 _debug("KIV REALM: %s", name); 985 986 eproto = tracepoint_string("rxkad_bad_len"); 987 if (end - p < 4 + 8 + 4 + 2) 988 goto bad_ticket; 989 990 /* get the IPv4 address of the entity that requested the ticket */ 991 memcpy(&addr, p, sizeof(addr)); 992 p += 4; 993 _debug("KIV ADDR : %pI4", &addr); 994 995 /* get the session key from the ticket */ 996 memcpy(&key, p, sizeof(key)); 997 p += 8; 998 _debug("KIV KEY : %08x %08x", ntohl(key.n[0]), ntohl(key.n[1])); 999 memcpy(_session_key, &key, sizeof(key)); 1000 1001 /* get the ticket's lifetime */ 1002 life = *p++ * 5 * 60; 1003 _debug("KIV LIFE : %u", life); 1004 1005 /* get the issue time of the ticket */ 1006 if (little_endian) { 1007 __le32 stamp; 1008 memcpy(&stamp, p, 4); 1009 issue = rxrpc_u32_to_time64(le32_to_cpu(stamp)); 1010 } else { 1011 __be32 stamp; 1012 memcpy(&stamp, p, 4); 1013 issue = rxrpc_u32_to_time64(be32_to_cpu(stamp)); 1014 } 1015 p += 4; 1016 now = ktime_get_real_seconds(); 1017 _debug("KIV ISSUE: %llx [%llx]", issue, now); 1018 1019 /* check the ticket is in date */ 1020 if (issue > now) { 1021 abort_code = RXKADNOAUTH; 1022 ret = -EKEYREJECTED; 1023 goto other_error; 1024 } 1025 1026 if (issue < now - life) { 1027 abort_code = RXKADEXPIRED; 1028 ret = -EKEYEXPIRED; 1029 goto other_error; 1030 } 1031 1032 *_expiry = issue + life; 1033 1034 /* get the service name */ 1035 name = Z(SNAME); 1036 _debug("KIV SNAME: %s", name); 1037 1038 /* get the service instance name */ 1039 name = Z(INST); 1040 _debug("KIV SINST: %s", name); 1041 return 0; 1042 1043 bad_ticket: 1044 trace_rxrpc_rx_eproto(NULL, sp->hdr.serial, eproto); 1045 abort_code = RXKADBADTICKET; 1046 ret = -EPROTO; 1047 other_error: 1048 *_abort_code = abort_code; 1049 return ret; 1050 temporary_error: 1051 return ret; 1052 } 1053 1054 /* 1055 * decrypt the response packet 1056 */ 1057 static void rxkad_decrypt_response(struct rxrpc_connection *conn, 1058 struct rxkad_response *resp, 1059 const struct rxrpc_crypt *session_key) 1060 { 1061 struct skcipher_request *req = rxkad_ci_req; 1062 struct scatterlist sg[1]; 1063 struct rxrpc_crypt iv; 1064 1065 _enter(",,%08x%08x", 1066 ntohl(session_key->n[0]), ntohl(session_key->n[1])); 1067 1068 mutex_lock(&rxkad_ci_mutex); 1069 if (crypto_sync_skcipher_setkey(rxkad_ci, session_key->x, 1070 sizeof(*session_key)) < 0) 1071 BUG(); 1072 1073 memcpy(&iv, session_key, sizeof(iv)); 1074 1075 sg_init_table(sg, 1); 1076 sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted)); 1077 skcipher_request_set_sync_tfm(req, rxkad_ci); 1078 skcipher_request_set_callback(req, 0, NULL, NULL); 1079 skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x); 1080 crypto_skcipher_decrypt(req); 1081 skcipher_request_zero(req); 1082 1083 mutex_unlock(&rxkad_ci_mutex); 1084 1085 _leave(""); 1086 } 1087 1088 /* 1089 * verify a response 1090 */ 1091 static int rxkad_verify_response(struct rxrpc_connection *conn, 1092 struct sk_buff *skb, 1093 u32 *_abort_code) 1094 { 1095 struct rxkad_response *response; 1096 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 1097 struct rxrpc_crypt session_key; 1098 struct key *server_key; 1099 const char *eproto; 1100 time64_t expiry; 1101 void *ticket; 1102 u32 abort_code, version, kvno, ticket_len, level; 1103 __be32 csum; 1104 int ret, i; 1105 1106 _enter("{%d}", conn->debug_id); 1107 1108 server_key = rxrpc_look_up_server_security(conn, skb, 0, 0); 1109 if (IS_ERR(server_key)) { 1110 switch (PTR_ERR(server_key)) { 1111 case -ENOKEY: 1112 abort_code = RXKADUNKNOWNKEY; 1113 break; 1114 case -EKEYEXPIRED: 1115 abort_code = RXKADEXPIRED; 1116 break; 1117 default: 1118 abort_code = RXKADNOAUTH; 1119 break; 1120 } 1121 trace_rxrpc_abort(0, "SVK", 1122 sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq, 1123 abort_code, PTR_ERR(server_key)); 1124 *_abort_code = abort_code; 1125 return -EPROTO; 1126 } 1127 1128 ret = -ENOMEM; 1129 response = kzalloc(sizeof(struct rxkad_response), GFP_NOFS); 1130 if (!response) 1131 goto temporary_error; 1132 1133 eproto = tracepoint_string("rxkad_rsp_short"); 1134 abort_code = RXKADPACKETSHORT; 1135 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header), 1136 response, sizeof(*response)) < 0) 1137 goto protocol_error; 1138 1139 version = ntohl(response->version); 1140 ticket_len = ntohl(response->ticket_len); 1141 kvno = ntohl(response->kvno); 1142 _proto("Rx RESPONSE %%%u { v=%u kv=%u tl=%u }", 1143 sp->hdr.serial, version, kvno, ticket_len); 1144 1145 eproto = tracepoint_string("rxkad_rsp_ver"); 1146 abort_code = RXKADINCONSISTENCY; 1147 if (version != RXKAD_VERSION) 1148 goto protocol_error; 1149 1150 eproto = tracepoint_string("rxkad_rsp_tktlen"); 1151 abort_code = RXKADTICKETLEN; 1152 if (ticket_len < 4 || ticket_len > MAXKRB5TICKETLEN) 1153 goto protocol_error; 1154 1155 eproto = tracepoint_string("rxkad_rsp_unkkey"); 1156 abort_code = RXKADUNKNOWNKEY; 1157 if (kvno >= RXKAD_TKT_TYPE_KERBEROS_V5) 1158 goto protocol_error; 1159 1160 /* extract the kerberos ticket and decrypt and decode it */ 1161 ret = -ENOMEM; 1162 ticket = kmalloc(ticket_len, GFP_NOFS); 1163 if (!ticket) 1164 goto temporary_error_free_resp; 1165 1166 eproto = tracepoint_string("rxkad_tkt_short"); 1167 abort_code = RXKADPACKETSHORT; 1168 ret = skb_copy_bits(skb, sizeof(struct rxrpc_wire_header) + sizeof(*response), 1169 ticket, ticket_len); 1170 if (ret < 0) 1171 goto temporary_error_free_ticket; 1172 1173 ret = rxkad_decrypt_ticket(conn, server_key, skb, ticket, ticket_len, 1174 &session_key, &expiry, _abort_code); 1175 if (ret < 0) 1176 goto temporary_error_free_ticket; 1177 1178 /* use the session key from inside the ticket to decrypt the 1179 * response */ 1180 rxkad_decrypt_response(conn, response, &session_key); 1181 1182 eproto = tracepoint_string("rxkad_rsp_param"); 1183 abort_code = RXKADSEALEDINCON; 1184 if (ntohl(response->encrypted.epoch) != conn->proto.epoch) 1185 goto protocol_error_free; 1186 if (ntohl(response->encrypted.cid) != conn->proto.cid) 1187 goto protocol_error_free; 1188 if (ntohl(response->encrypted.securityIndex) != conn->security_ix) 1189 goto protocol_error_free; 1190 csum = response->encrypted.checksum; 1191 response->encrypted.checksum = 0; 1192 rxkad_calc_response_checksum(response); 1193 eproto = tracepoint_string("rxkad_rsp_csum"); 1194 if (response->encrypted.checksum != csum) 1195 goto protocol_error_free; 1196 1197 spin_lock(&conn->bundle->channel_lock); 1198 for (i = 0; i < RXRPC_MAXCALLS; i++) { 1199 struct rxrpc_call *call; 1200 u32 call_id = ntohl(response->encrypted.call_id[i]); 1201 1202 eproto = tracepoint_string("rxkad_rsp_callid"); 1203 if (call_id > INT_MAX) 1204 goto protocol_error_unlock; 1205 1206 eproto = tracepoint_string("rxkad_rsp_callctr"); 1207 if (call_id < conn->channels[i].call_counter) 1208 goto protocol_error_unlock; 1209 1210 eproto = tracepoint_string("rxkad_rsp_callst"); 1211 if (call_id > conn->channels[i].call_counter) { 1212 call = rcu_dereference_protected( 1213 conn->channels[i].call, 1214 lockdep_is_held(&conn->bundle->channel_lock)); 1215 if (call && call->state < RXRPC_CALL_COMPLETE) 1216 goto protocol_error_unlock; 1217 conn->channels[i].call_counter = call_id; 1218 } 1219 } 1220 spin_unlock(&conn->bundle->channel_lock); 1221 1222 eproto = tracepoint_string("rxkad_rsp_seq"); 1223 abort_code = RXKADOUTOFSEQUENCE; 1224 if (ntohl(response->encrypted.inc_nonce) != conn->rxkad.nonce + 1) 1225 goto protocol_error_free; 1226 1227 eproto = tracepoint_string("rxkad_rsp_level"); 1228 abort_code = RXKADLEVELFAIL; 1229 level = ntohl(response->encrypted.level); 1230 if (level > RXRPC_SECURITY_ENCRYPT) 1231 goto protocol_error_free; 1232 conn->params.security_level = level; 1233 1234 /* create a key to hold the security data and expiration time - after 1235 * this the connection security can be handled in exactly the same way 1236 * as for a client connection */ 1237 ret = rxrpc_get_server_data_key(conn, &session_key, expiry, kvno); 1238 if (ret < 0) 1239 goto temporary_error_free_ticket; 1240 1241 kfree(ticket); 1242 kfree(response); 1243 _leave(" = 0"); 1244 return 0; 1245 1246 protocol_error_unlock: 1247 spin_unlock(&conn->bundle->channel_lock); 1248 protocol_error_free: 1249 kfree(ticket); 1250 protocol_error: 1251 kfree(response); 1252 trace_rxrpc_rx_eproto(NULL, sp->hdr.serial, eproto); 1253 key_put(server_key); 1254 *_abort_code = abort_code; 1255 return -EPROTO; 1256 1257 temporary_error_free_ticket: 1258 kfree(ticket); 1259 temporary_error_free_resp: 1260 kfree(response); 1261 temporary_error: 1262 /* Ignore the response packet if we got a temporary error such as 1263 * ENOMEM. We just want to send the challenge again. Note that we 1264 * also come out this way if the ticket decryption fails. 1265 */ 1266 key_put(server_key); 1267 return ret; 1268 } 1269 1270 /* 1271 * clear the connection security 1272 */ 1273 static void rxkad_clear(struct rxrpc_connection *conn) 1274 { 1275 _enter(""); 1276 1277 if (conn->rxkad.cipher) 1278 crypto_free_sync_skcipher(conn->rxkad.cipher); 1279 } 1280 1281 /* 1282 * Initialise the rxkad security service. 1283 */ 1284 static int rxkad_init(void) 1285 { 1286 struct crypto_sync_skcipher *tfm; 1287 struct skcipher_request *req; 1288 1289 /* pin the cipher we need so that the crypto layer doesn't invoke 1290 * keventd to go get it */ 1291 tfm = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0); 1292 if (IS_ERR(tfm)) 1293 return PTR_ERR(tfm); 1294 1295 req = skcipher_request_alloc(&tfm->base, GFP_KERNEL); 1296 if (!req) 1297 goto nomem_tfm; 1298 1299 rxkad_ci_req = req; 1300 rxkad_ci = tfm; 1301 return 0; 1302 1303 nomem_tfm: 1304 crypto_free_sync_skcipher(tfm); 1305 return -ENOMEM; 1306 } 1307 1308 /* 1309 * Clean up the rxkad security service. 1310 */ 1311 static void rxkad_exit(void) 1312 { 1313 crypto_free_sync_skcipher(rxkad_ci); 1314 skcipher_request_free(rxkad_ci_req); 1315 } 1316 1317 /* 1318 * RxRPC Kerberos-based security 1319 */ 1320 const struct rxrpc_security rxkad = { 1321 .name = "rxkad", 1322 .security_index = RXRPC_SECURITY_RXKAD, 1323 .no_key_abort = RXKADUNKNOWNKEY, 1324 .init = rxkad_init, 1325 .exit = rxkad_exit, 1326 .preparse_server_key = rxkad_preparse_server_key, 1327 .free_preparse_server_key = rxkad_free_preparse_server_key, 1328 .destroy_server_key = rxkad_destroy_server_key, 1329 .init_connection_security = rxkad_init_connection_security, 1330 .how_much_data = rxkad_how_much_data, 1331 .secure_packet = rxkad_secure_packet, 1332 .verify_packet = rxkad_verify_packet, 1333 .free_call_crypto = rxkad_free_call_crypto, 1334 .issue_challenge = rxkad_issue_challenge, 1335 .respond_to_challenge = rxkad_respond_to_challenge, 1336 .verify_response = rxkad_verify_response, 1337 .clear = rxkad_clear, 1338 }; 1339