1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* GSSAPI-based RxRPC security 3 * 4 * Copyright (C) 2025 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 <linux/net.h> 11 #include <linux/skbuff.h> 12 #include <linux/slab.h> 13 #include <linux/key-type.h> 14 #include "ar-internal.h" 15 #include "rxgk_common.h" 16 17 /* 18 * Parse the information from a server key 19 */ 20 static int rxgk_preparse_server_key(struct key_preparsed_payload *prep) 21 { 22 const struct krb5_enctype *krb5; 23 struct krb5_buffer *server_key = (void *)&prep->payload.data[2]; 24 unsigned int service, sec_class, kvno, enctype; 25 int n = 0; 26 27 _enter("%zu", prep->datalen); 28 29 if (sscanf(prep->orig_description, "%u:%u:%u:%u%n", 30 &service, &sec_class, &kvno, &enctype, &n) != 4) 31 return -EINVAL; 32 33 if (prep->orig_description[n]) 34 return -EINVAL; 35 36 krb5 = crypto_krb5_find_enctype(enctype); 37 if (!krb5) 38 return -ENOPKG; 39 40 prep->payload.data[0] = (struct krb5_enctype *)krb5; 41 42 if (prep->datalen != krb5->key_len) 43 return -EKEYREJECTED; 44 45 server_key->len = prep->datalen; 46 server_key->data = kmemdup(prep->data, prep->datalen, GFP_KERNEL); 47 if (!server_key->data) 48 return -ENOMEM; 49 50 _leave(" = 0"); 51 return 0; 52 } 53 54 static void rxgk_free_server_key(union key_payload *payload) 55 { 56 struct krb5_buffer *server_key = (void *)&payload->data[2]; 57 58 kfree_sensitive(server_key->data); 59 } 60 61 static void rxgk_free_preparse_server_key(struct key_preparsed_payload *prep) 62 { 63 rxgk_free_server_key(&prep->payload); 64 } 65 66 static void rxgk_destroy_server_key(struct key *key) 67 { 68 rxgk_free_server_key(&key->payload); 69 } 70 71 static void rxgk_describe_server_key(const struct key *key, struct seq_file *m) 72 { 73 const struct krb5_enctype *krb5 = key->payload.data[0]; 74 75 if (krb5) 76 seq_printf(m, ": %s", krb5->name); 77 } 78 79 /* 80 * Handle rekeying the connection when we see our limits overrun or when the 81 * far side decided to rekey. 82 * 83 * Returns a ref on the context if successful or -ESTALE if the key is out of 84 * date. 85 */ 86 static struct rxgk_context *rxgk_rekey(struct rxrpc_connection *conn, 87 const u16 *specific_key_number) 88 { 89 struct rxgk_context *gk, *dead = NULL; 90 unsigned int key_number, current_key, mask = ARRAY_SIZE(conn->rxgk.keys) - 1; 91 bool crank = false; 92 93 _enter("%d", specific_key_number ? *specific_key_number : -1); 94 95 mutex_lock(&conn->security_lock); 96 97 current_key = conn->rxgk.key_number; 98 if (!specific_key_number) { 99 key_number = current_key; 100 } else { 101 if (*specific_key_number == (u16)current_key) 102 key_number = current_key; 103 else if (*specific_key_number == (u16)(current_key - 1)) 104 key_number = current_key - 1; 105 else if (*specific_key_number == (u16)(current_key + 1)) 106 goto crank_window; 107 else 108 goto bad_key; 109 } 110 111 gk = conn->rxgk.keys[key_number & mask]; 112 if (!gk) 113 goto generate_key; 114 if (!specific_key_number && 115 test_bit(RXGK_TK_NEEDS_REKEY, &gk->flags)) 116 goto crank_window; 117 118 grab: 119 refcount_inc(&gk->usage); 120 mutex_unlock(&conn->security_lock); 121 rxgk_put(dead); 122 return gk; 123 124 crank_window: 125 trace_rxrpc_rxgk_rekey(conn, current_key, 126 specific_key_number ? *specific_key_number : -1); 127 if (current_key == UINT_MAX) 128 goto bad_key; 129 if (current_key + 1 == UINT_MAX) 130 set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags); 131 132 key_number = current_key + 1; 133 if (WARN_ON(conn->rxgk.keys[key_number & mask])) 134 goto bad_key; 135 crank = true; 136 137 generate_key: 138 gk = conn->rxgk.keys[current_key & mask]; 139 gk = rxgk_generate_transport_key(conn, gk->key, key_number, GFP_NOFS); 140 if (IS_ERR(gk)) { 141 mutex_unlock(&conn->security_lock); 142 return gk; 143 } 144 145 write_lock(&conn->security_use_lock); 146 if (crank) { 147 current_key++; 148 conn->rxgk.key_number = current_key; 149 dead = conn->rxgk.keys[(current_key - 2) & mask]; 150 conn->rxgk.keys[(current_key - 2) & mask] = NULL; 151 } 152 conn->rxgk.keys[current_key & mask] = gk; 153 write_unlock(&conn->security_use_lock); 154 goto grab; 155 156 bad_key: 157 mutex_unlock(&conn->security_lock); 158 return ERR_PTR(-ESTALE); 159 } 160 161 /* 162 * Get the specified keying context. 163 * 164 * Returns a ref on the context if successful or -ESTALE if the key is out of 165 * date. 166 */ 167 static struct rxgk_context *rxgk_get_key(struct rxrpc_connection *conn, 168 const u16 *specific_key_number) 169 { 170 struct rxgk_context *gk; 171 unsigned int key_number, current_key, mask = ARRAY_SIZE(conn->rxgk.keys) - 1; 172 173 _enter("{%u},%d", 174 conn->rxgk.key_number, specific_key_number ? *specific_key_number : -1); 175 176 read_lock(&conn->security_use_lock); 177 178 current_key = conn->rxgk.key_number; 179 if (!specific_key_number) { 180 key_number = current_key; 181 } else { 182 /* Only the bottom 16 bits of the key number are exposed in the 183 * header, so we try and keep the upper 16 bits in step. The 184 * whole 32 bits are used to generate the TK. 185 */ 186 if (*specific_key_number == (u16)current_key) 187 key_number = current_key; 188 else if (*specific_key_number == (u16)(current_key - 1)) 189 key_number = current_key - 1; 190 else if (*specific_key_number == (u16)(current_key + 1)) 191 goto rekey; 192 else 193 goto bad_key; 194 } 195 196 gk = conn->rxgk.keys[key_number & mask]; 197 if (!gk) 198 goto slow_path; 199 if (!specific_key_number && 200 key_number < UINT_MAX) { 201 if (time_after(jiffies, gk->expiry) || 202 gk->bytes_remaining < 0) { 203 set_bit(RXGK_TK_NEEDS_REKEY, &gk->flags); 204 goto slow_path; 205 } 206 207 if (test_bit(RXGK_TK_NEEDS_REKEY, &gk->flags)) 208 goto slow_path; 209 } 210 211 refcount_inc(&gk->usage); 212 read_unlock(&conn->security_use_lock); 213 return gk; 214 215 rekey: 216 _debug("rekey"); 217 if (current_key == UINT_MAX) 218 goto bad_key; 219 gk = conn->rxgk.keys[current_key & mask]; 220 if (gk) 221 set_bit(RXGK_TK_NEEDS_REKEY, &gk->flags); 222 slow_path: 223 read_unlock(&conn->security_use_lock); 224 return rxgk_rekey(conn, specific_key_number); 225 bad_key: 226 read_unlock(&conn->security_use_lock); 227 return ERR_PTR(-ESTALE); 228 } 229 230 /* 231 * initialise connection security 232 */ 233 static int rxgk_init_connection_security(struct rxrpc_connection *conn, 234 struct rxrpc_key_token *token) 235 { 236 struct rxgk_context *gk; 237 int ret; 238 239 _enter("{%d,%u},{%x}", 240 conn->debug_id, conn->rxgk.key_number, key_serial(conn->key)); 241 242 conn->security_ix = token->security_index; 243 conn->security_level = token->rxgk->level; 244 245 if (rxrpc_conn_is_client(conn)) { 246 conn->rxgk.start_time = ktime_get(); 247 do_div(conn->rxgk.start_time, 100); 248 } 249 250 gk = rxgk_generate_transport_key(conn, token->rxgk, conn->rxgk.key_number, 251 GFP_NOFS); 252 if (IS_ERR(gk)) 253 return PTR_ERR(gk); 254 conn->rxgk.enctype = gk->krb5->etype; 255 conn->rxgk.keys[gk->key_number & 3] = gk; 256 257 switch (conn->security_level) { 258 case RXRPC_SECURITY_PLAIN: 259 case RXRPC_SECURITY_AUTH: 260 case RXRPC_SECURITY_ENCRYPT: 261 break; 262 default: 263 ret = -EKEYREJECTED; 264 goto error; 265 } 266 267 ret = 0; 268 error: 269 _leave(" = %d", ret); 270 return ret; 271 } 272 273 /* 274 * Clean up the crypto on a call. 275 */ 276 static void rxgk_free_call_crypto(struct rxrpc_call *call) 277 { 278 } 279 280 /* 281 * Work out how much data we can put in a packet. 282 */ 283 static struct rxrpc_txbuf *rxgk_alloc_txbuf(struct rxrpc_call *call, size_t remain, gfp_t gfp) 284 { 285 enum krb5_crypto_mode mode; 286 struct rxgk_context *gk; 287 struct rxrpc_txbuf *txb; 288 size_t shdr, alloc, limit, part, offset, gap; 289 290 switch (call->conn->security_level) { 291 default: 292 alloc = umin(remain, RXRPC_JUMBO_DATALEN); 293 return rxrpc_alloc_data_txbuf(call, alloc, 1, gfp); 294 case RXRPC_SECURITY_AUTH: 295 shdr = 0; 296 mode = KRB5_CHECKSUM_MODE; 297 break; 298 case RXRPC_SECURITY_ENCRYPT: 299 shdr = sizeof(struct rxgk_header); 300 mode = KRB5_ENCRYPT_MODE; 301 break; 302 } 303 304 gk = rxgk_get_key(call->conn, NULL); 305 if (IS_ERR(gk)) 306 return NULL; 307 308 /* Work out the maximum amount of data that will fit. */ 309 alloc = RXRPC_JUMBO_DATALEN; 310 limit = crypto_krb5_how_much_data(gk->krb5, mode, &alloc, &offset); 311 312 if (remain < limit - shdr) { 313 part = remain; 314 alloc = crypto_krb5_how_much_buffer(gk->krb5, mode, 315 shdr + part, &offset); 316 gap = 0; 317 } else { 318 part = limit - shdr; 319 gap = RXRPC_JUMBO_DATALEN - alloc; 320 alloc = RXRPC_JUMBO_DATALEN; 321 } 322 323 rxgk_put(gk); 324 325 txb = rxrpc_alloc_data_txbuf(call, alloc, 16, gfp); 326 if (!txb) 327 return NULL; 328 329 txb->crypto_header = offset; 330 txb->sec_header = shdr; 331 txb->offset += offset + shdr; 332 txb->space = part; 333 334 /* Clear excess space in the packet */ 335 if (gap) 336 memset(txb->data + alloc - gap, 0, gap); 337 return txb; 338 } 339 340 /* 341 * Integrity mode (sign a packet - level 1 security) 342 */ 343 static int rxgk_secure_packet_integrity(const struct rxrpc_call *call, 344 struct rxgk_context *gk, 345 struct rxrpc_txbuf *txb) 346 { 347 struct rxgk_header *hdr; 348 struct scatterlist sg[1]; 349 struct krb5_buffer metadata; 350 int ret = -ENOMEM; 351 352 _enter(""); 353 354 hdr = kzalloc_obj(*hdr, GFP_NOFS); 355 if (!hdr) 356 goto error_gk; 357 358 hdr->epoch = htonl(call->conn->proto.epoch); 359 hdr->cid = htonl(call->cid); 360 hdr->call_number = htonl(call->call_id); 361 hdr->seq = htonl(txb->seq); 362 hdr->sec_index = htonl(call->security_ix); 363 hdr->data_len = htonl(txb->len); 364 metadata.len = sizeof(*hdr); 365 metadata.data = hdr; 366 367 sg_init_table(sg, 1); 368 sg_set_buf(&sg[0], txb->data, txb->alloc_size); 369 370 ret = crypto_krb5_get_mic(gk->krb5, gk->tx_Kc, &metadata, 371 sg, 1, txb->alloc_size, 372 txb->crypto_header, txb->sec_header + txb->len); 373 if (ret >= 0) { 374 txb->pkt_len = ret; 375 if (txb->alloc_size == RXRPC_JUMBO_DATALEN) 376 txb->jumboable = true; 377 gk->bytes_remaining -= ret; 378 } 379 kfree(hdr); 380 error_gk: 381 rxgk_put(gk); 382 _leave(" = %d", ret); 383 return ret; 384 } 385 386 /* 387 * wholly encrypt a packet (level 2 security) 388 */ 389 static int rxgk_secure_packet_encrypted(const struct rxrpc_call *call, 390 struct rxgk_context *gk, 391 struct rxrpc_txbuf *txb) 392 { 393 struct rxgk_header *hdr; 394 struct scatterlist sg[1]; 395 int ret; 396 397 _enter("%x", txb->len); 398 399 /* Insert the header into the buffer. */ 400 hdr = txb->data + txb->crypto_header; 401 hdr->epoch = htonl(call->conn->proto.epoch); 402 hdr->cid = htonl(call->cid); 403 hdr->call_number = htonl(call->call_id); 404 hdr->seq = htonl(txb->seq); 405 hdr->sec_index = htonl(call->security_ix); 406 hdr->data_len = htonl(txb->len); 407 408 sg_init_table(sg, 1); 409 sg_set_buf(&sg[0], txb->data, txb->alloc_size); 410 411 ret = crypto_krb5_encrypt(gk->krb5, gk->tx_enc, 412 sg, 1, txb->alloc_size, 413 txb->crypto_header, txb->sec_header + txb->len, 414 false); 415 if (ret >= 0) { 416 txb->pkt_len = ret; 417 if (txb->alloc_size == RXRPC_JUMBO_DATALEN) 418 txb->jumboable = true; 419 gk->bytes_remaining -= ret; 420 } 421 422 rxgk_put(gk); 423 _leave(" = %d", ret); 424 return ret; 425 } 426 427 /* 428 * checksum an RxRPC packet header 429 */ 430 static int rxgk_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb) 431 { 432 struct rxgk_context *gk; 433 int ret; 434 435 _enter("{%d{%x}},{#%u},%u,", 436 call->debug_id, key_serial(call->conn->key), txb->seq, txb->len); 437 438 gk = rxgk_get_key(call->conn, NULL); 439 if (IS_ERR(gk)) 440 return PTR_ERR(gk) == -ESTALE ? -EKEYREJECTED : PTR_ERR(gk); 441 442 ret = key_validate(call->conn->key); 443 if (ret < 0) { 444 rxgk_put(gk); 445 return ret; 446 } 447 448 call->security_enctype = gk->krb5->etype; 449 txb->cksum = htons(gk->key_number); 450 451 switch (call->conn->security_level) { 452 case RXRPC_SECURITY_PLAIN: 453 rxgk_put(gk); 454 txb->pkt_len = txb->len; 455 return 0; 456 case RXRPC_SECURITY_AUTH: 457 return rxgk_secure_packet_integrity(call, gk, txb); 458 case RXRPC_SECURITY_ENCRYPT: 459 return rxgk_secure_packet_encrypted(call, gk, txb); 460 default: 461 rxgk_put(gk); 462 return -EPERM; 463 } 464 } 465 466 /* 467 * Integrity mode (check the signature on a packet - level 1 security) 468 */ 469 static int rxgk_verify_packet_integrity(struct rxrpc_call *call, 470 struct rxgk_context *gk, 471 struct sk_buff *skb) 472 { 473 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 474 struct rxgk_header *hdr; 475 struct krb5_buffer metadata; 476 unsigned int len = call->rx_dec_len; 477 size_t data_offset = 0, data_len = len; 478 void *data = call->rx_dec_buffer, *p = data; 479 u32 ac = 0; 480 int ret = -ENOMEM; 481 482 _enter(""); 483 484 if (crypto_krb5_where_is_the_data(gk->krb5, KRB5_CHECKSUM_MODE, 485 &data_offset, &data_len) < 0) { 486 ret = rxrpc_abort_eproto(call, skb, RXGK_PACKETSHORT, 487 rxgk_abort_1_short_header); 488 goto put_gk; 489 } 490 491 hdr = kzalloc_obj(*hdr, GFP_NOFS); 492 if (!hdr) 493 goto put_gk; 494 495 hdr->epoch = htonl(call->conn->proto.epoch); 496 hdr->cid = htonl(call->cid); 497 hdr->call_number = htonl(call->call_id); 498 hdr->seq = htonl(sp->hdr.seq); 499 hdr->sec_index = htonl(call->security_ix); 500 hdr->data_len = htonl(data_len); 501 502 metadata.len = sizeof(*hdr); 503 metadata.data = hdr; 504 ret = rxgk_verify_mic(gk->krb5, gk->rx_Kc, &metadata, &p, &len, &ac); 505 kfree(hdr); 506 if (ret < 0) { 507 if (ret != -ENOMEM) 508 rxrpc_abort_eproto(call, skb, ac, 509 rxgk_abort_1_verify_mic_eproto); 510 } else { 511 call->rx_dec_offset = p - data; 512 call->rx_dec_len = len; 513 } 514 515 put_gk: 516 rxgk_put(gk); 517 _leave(" = %d", ret); 518 return ret; 519 } 520 521 /* 522 * Decrypt an encrypted packet (level 2 security). 523 */ 524 static int rxgk_verify_packet_encrypted(struct rxrpc_call *call, 525 struct rxgk_context *gk, 526 struct sk_buff *skb) 527 { 528 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 529 struct rxgk_header *hdr; 530 unsigned int offset = 0, len = call->rx_dec_len; 531 void *data = call->rx_dec_buffer, *p = data; 532 int ret; 533 u32 ac = 0; 534 535 _enter(""); 536 537 if (crypto_krb5_check_data_len(gk->krb5, KRB5_ENCRYPT_MODE, 538 len, sizeof(*hdr)) < 0) { 539 ret = rxrpc_abort_eproto(call, skb, RXGK_PACKETSHORT, 540 rxgk_abort_2_short_header); 541 goto error; 542 } 543 544 ret = rxgk_decrypt(gk->krb5, gk->rx_enc, &p, &len, &ac); 545 if (ret < 0) { 546 if (ret != -ENOMEM) 547 rxrpc_abort_eproto(call, skb, ac, rxgk_abort_2_decrypt_eproto); 548 goto error; 549 } 550 offset = p - data; 551 552 if (len < sizeof(*hdr)) { 553 ret = rxrpc_abort_eproto(call, skb, RXGK_PACKETSHORT, 554 rxgk_abort_2_short_header); 555 goto error; 556 } 557 558 /* Extract the header from the skb */ 559 hdr = data + offset; 560 offset += sizeof(*hdr); 561 len -= sizeof(*hdr); 562 563 if (ntohl(hdr->epoch) != call->conn->proto.epoch || 564 ntohl(hdr->cid) != call->cid || 565 ntohl(hdr->call_number) != call->call_id || 566 ntohl(hdr->seq) != sp->hdr.seq || 567 ntohl(hdr->sec_index) != call->security_ix || 568 ntohl(hdr->data_len) > len) { 569 ret = rxrpc_abort_eproto(call, skb, RXGK_SEALEDINCON, 570 rxgk_abort_2_short_data); 571 goto error; 572 } 573 574 call->rx_dec_offset = offset; 575 call->rx_dec_len = ntohl(hdr->data_len); 576 ret = 0; 577 error: 578 rxgk_put(gk); 579 _leave(" = %d", ret); 580 return ret; 581 } 582 583 /* 584 * Verify the security on a received packet or subpacket (if part of a 585 * jumbo packet). 586 */ 587 static int rxgk_verify_packet(struct rxrpc_call *call, struct sk_buff *skb) 588 { 589 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 590 struct rxgk_context *gk; 591 u16 key_number = sp->hdr.cksum; 592 593 _enter("{%d{%x}},{#%u}", 594 call->debug_id, key_serial(call->conn->key), sp->hdr.seq); 595 596 gk = rxgk_get_key(call->conn, &key_number); 597 if (IS_ERR(gk)) { 598 switch (PTR_ERR(gk)) { 599 case -ESTALE: 600 return rxrpc_abort_eproto(call, skb, RXGK_BADKEYNO, 601 rxgk_abort_bad_key_number); 602 default: 603 return PTR_ERR(gk); 604 } 605 } 606 607 call->security_enctype = gk->krb5->etype; 608 switch (call->conn->security_level) { 609 case RXRPC_SECURITY_PLAIN: 610 rxgk_put(gk); 611 return 0; 612 case RXRPC_SECURITY_AUTH: 613 return rxgk_verify_packet_integrity(call, gk, skb); 614 case RXRPC_SECURITY_ENCRYPT: 615 return rxgk_verify_packet_encrypted(call, gk, skb); 616 default: 617 rxgk_put(gk); 618 return -ENOANO; 619 } 620 } 621 622 /* 623 * Allocate memory to hold a challenge or a response packet. We're not running 624 * in the io_thread, so we can't use ->tx_alloc. 625 */ 626 static struct page *rxgk_alloc_packet(size_t total_len) 627 { 628 gfp_t gfp = GFP_NOFS; 629 int order; 630 631 order = get_order(total_len); 632 if (order > 0) 633 gfp |= __GFP_COMP; 634 return alloc_pages(gfp, order); 635 } 636 637 /* 638 * Issue a challenge. 639 */ 640 static int rxgk_issue_challenge(struct rxrpc_connection *conn) 641 { 642 struct rxrpc_wire_header *whdr; 643 struct bio_vec bvec[1]; 644 struct msghdr msg; 645 struct page *page; 646 size_t len = sizeof(*whdr) + sizeof(conn->rxgk.nonce); 647 u32 serial; 648 int ret; 649 650 _enter("{%d}", conn->debug_id); 651 652 get_random_bytes(&conn->rxgk.nonce, sizeof(conn->rxgk.nonce)); 653 654 /* We can't use conn->tx_alloc without a lock */ 655 page = rxgk_alloc_packet(sizeof(*whdr) + sizeof(conn->rxgk.nonce)); 656 if (!page) 657 return -ENOMEM; 658 659 bvec_set_page(&bvec[0], page, len, 0); 660 iov_iter_bvec(&msg.msg_iter, WRITE, bvec, 1, len); 661 662 msg.msg_name = &conn->peer->srx.transport; 663 msg.msg_namelen = conn->peer->srx.transport_len; 664 msg.msg_control = NULL; 665 msg.msg_controllen = 0; 666 msg.msg_flags = MSG_SPLICE_PAGES; 667 668 whdr = page_address(page); 669 whdr->epoch = htonl(conn->proto.epoch); 670 whdr->cid = htonl(conn->proto.cid); 671 whdr->callNumber = 0; 672 whdr->seq = 0; 673 whdr->type = RXRPC_PACKET_TYPE_CHALLENGE; 674 whdr->flags = conn->out_clientflag; 675 whdr->userStatus = 0; 676 whdr->securityIndex = conn->security_ix; 677 whdr->_rsvd = 0; 678 whdr->serviceId = htons(conn->service_id); 679 680 memcpy(whdr + 1, conn->rxgk.nonce, sizeof(conn->rxgk.nonce)); 681 682 serial = rxrpc_get_next_serials(conn, 1); 683 whdr->serial = htonl(serial); 684 685 trace_rxrpc_tx_challenge(conn, serial, 0, *(u32 *)&conn->rxgk.nonce); 686 687 ret = do_udp_sendmsg(conn->local->socket, &msg, len); 688 if (ret > 0) 689 rxrpc_peer_mark_tx(conn->peer); 690 __free_page(page); 691 692 if (ret < 0) { 693 trace_rxrpc_tx_fail(conn->debug_id, serial, ret, 694 rxrpc_tx_point_rxgk_challenge); 695 return -EAGAIN; 696 } 697 698 trace_rxrpc_tx_packet(conn->debug_id, whdr, 699 rxrpc_tx_point_rxgk_challenge); 700 _leave(" = 0"); 701 return 0; 702 } 703 704 /* 705 * Validate a challenge packet. 706 */ 707 static bool rxgk_validate_challenge(struct rxrpc_connection *conn, 708 struct sk_buff *skb) 709 { 710 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 711 u8 nonce[20]; 712 713 if (!conn->key) { 714 rxrpc_abort_conn(conn, skb, RX_PROTOCOL_ERROR, -EPROTO, 715 rxgk_abort_chall_no_key); 716 return false; 717 } 718 719 if (key_validate(conn->key) < 0) { 720 rxrpc_abort_conn(conn, skb, RXGK_EXPIRED, -EPROTO, 721 rxgk_abort_chall_key_expired); 722 return false; 723 } 724 725 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header), 726 nonce, sizeof(nonce)) < 0) { 727 rxrpc_abort_conn(conn, skb, RXGK_PACKETSHORT, -EPROTO, 728 rxgk_abort_chall_short); 729 return false; 730 } 731 732 trace_rxrpc_rx_challenge(conn, sp->hdr.serial, 0, *(u32 *)nonce, 0); 733 return true; 734 } 735 736 /** 737 * rxgk_kernel_query_challenge - Query RxGK-specific challenge parameters 738 * @challenge: The challenge packet to query 739 * 740 * Return: The Kerberos 5 encoding type for the challenged connection. 741 */ 742 u32 rxgk_kernel_query_challenge(struct sk_buff *challenge) 743 { 744 struct rxrpc_skb_priv *sp = rxrpc_skb(challenge); 745 746 return sp->chall.conn->rxgk.enctype; 747 } 748 EXPORT_SYMBOL(rxgk_kernel_query_challenge); 749 750 /* 751 * Fill out the control message to pass to userspace to inform about the 752 * challenge. 753 */ 754 static int rxgk_challenge_to_recvmsg(struct rxrpc_connection *conn, 755 struct sk_buff *challenge, 756 struct msghdr *msg) 757 { 758 struct rxgk_challenge chall; 759 760 chall.base.service_id = conn->service_id; 761 chall.base.security_index = conn->security_ix; 762 chall.enctype = conn->rxgk.enctype; 763 764 return put_cmsg(msg, SOL_RXRPC, RXRPC_CHALLENGED, sizeof(chall), &chall); 765 } 766 767 /* 768 * Insert the requisite amount of XDR padding for the length given. 769 */ 770 static int rxgk_pad_out(struct sk_buff *response, size_t len, size_t offset) 771 { 772 __be32 zero = 0; 773 size_t pad = xdr_round_up(len) - len; 774 int ret; 775 776 if (!pad) 777 return 0; 778 779 ret = skb_store_bits(response, offset, &zero, pad); 780 if (ret < 0) 781 return ret; 782 return pad; 783 } 784 785 /* 786 * Insert the header into the response. 787 */ 788 static noinline ssize_t rxgk_insert_response_header(struct rxrpc_connection *conn, 789 struct rxgk_context *gk, 790 struct sk_buff *response, 791 size_t offset) 792 { 793 struct rxrpc_skb_priv *rsp = rxrpc_skb(response); 794 795 struct { 796 struct rxrpc_wire_header whdr; 797 __be32 start_time_msw; 798 __be32 start_time_lsw; 799 __be32 ticket_len; 800 } h; 801 int ret; 802 803 rsp->resp.kvno = gk->key_number; 804 rsp->resp.version = gk->krb5->etype; 805 806 h.whdr.epoch = htonl(conn->proto.epoch); 807 h.whdr.cid = htonl(conn->proto.cid); 808 h.whdr.callNumber = 0; 809 h.whdr.serial = 0; 810 h.whdr.seq = 0; 811 h.whdr.type = RXRPC_PACKET_TYPE_RESPONSE; 812 h.whdr.flags = conn->out_clientflag; 813 h.whdr.userStatus = 0; 814 h.whdr.securityIndex = conn->security_ix; 815 h.whdr.cksum = htons(gk->key_number); 816 h.whdr.serviceId = htons(conn->service_id); 817 h.start_time_msw = htonl(upper_32_bits(conn->rxgk.start_time)); 818 h.start_time_lsw = htonl(lower_32_bits(conn->rxgk.start_time)); 819 h.ticket_len = htonl(gk->key->ticket.len); 820 821 ret = skb_store_bits(response, offset, &h, sizeof(h)); 822 return ret < 0 ? ret : sizeof(h); 823 } 824 825 /* 826 * Construct the authenticator to go in the response packet 827 * 828 * struct RXGK_Authenticator { 829 * opaque nonce[20]; 830 * opaque appdata<>; 831 * RXGK_Level level; 832 * unsigned int epoch; 833 * unsigned int cid; 834 * unsigned int call_numbers<>; 835 * }; 836 */ 837 static ssize_t rxgk_construct_authenticator(struct rxrpc_connection *conn, 838 struct sk_buff *challenge, 839 const struct krb5_buffer *appdata, 840 struct sk_buff *response, 841 size_t offset) 842 { 843 struct { 844 u8 nonce[20]; 845 __be32 appdata_len; 846 } a; 847 struct { 848 __be32 level; 849 __be32 epoch; 850 __be32 cid; 851 __be32 call_numbers_count; 852 __be32 call_numbers[4]; 853 } b; 854 int ret; 855 856 ret = skb_copy_bits(challenge, sizeof(struct rxrpc_wire_header), 857 a.nonce, sizeof(a.nonce)); 858 if (ret < 0) 859 return -EPROTO; 860 861 a.appdata_len = htonl(appdata->len); 862 863 ret = skb_store_bits(response, offset, &a, sizeof(a)); 864 if (ret < 0) 865 return ret; 866 offset += sizeof(a); 867 868 if (appdata->len) { 869 ret = skb_store_bits(response, offset, appdata->data, appdata->len); 870 if (ret < 0) 871 return ret; 872 offset += appdata->len; 873 874 ret = rxgk_pad_out(response, appdata->len, offset); 875 if (ret < 0) 876 return ret; 877 offset += ret; 878 } 879 880 b.level = htonl(conn->security_level); 881 b.epoch = htonl(conn->proto.epoch); 882 b.cid = htonl(conn->proto.cid); 883 b.call_numbers_count = htonl(4); 884 b.call_numbers[0] = htonl(conn->channels[0].call_counter); 885 b.call_numbers[1] = htonl(conn->channels[1].call_counter); 886 b.call_numbers[2] = htonl(conn->channels[2].call_counter); 887 b.call_numbers[3] = htonl(conn->channels[3].call_counter); 888 889 ret = skb_store_bits(response, offset, &b, sizeof(b)); 890 if (ret < 0) 891 return ret; 892 return sizeof(a) + xdr_round_up(appdata->len) + sizeof(b); 893 } 894 895 static ssize_t rxgk_encrypt_authenticator(struct rxrpc_connection *conn, 896 struct rxgk_context *gk, 897 struct sk_buff *response, 898 size_t offset, 899 size_t alloc_len, 900 size_t auth_offset, 901 size_t auth_len) 902 { 903 struct scatterlist sg[16]; 904 int nr_sg; 905 906 sg_init_table(sg, ARRAY_SIZE(sg)); 907 nr_sg = skb_to_sgvec(response, sg, offset, alloc_len); 908 if (unlikely(nr_sg < 0)) 909 return nr_sg; 910 return crypto_krb5_encrypt(gk->krb5, gk->resp_enc, sg, nr_sg, alloc_len, 911 auth_offset, auth_len, false); 912 } 913 914 /* 915 * Construct the response. 916 * 917 * struct RXGK_Response { 918 * rxgkTime start_time; 919 * RXGK_Data token; 920 * opaque authenticator<RXGK_MAXAUTHENTICATOR> 921 * }; 922 */ 923 static int rxgk_construct_response(struct rxrpc_connection *conn, 924 struct sk_buff *challenge, 925 struct krb5_buffer *appdata) 926 { 927 struct rxrpc_skb_priv *csp, *rsp; 928 struct rxgk_context *gk; 929 struct sk_buff *response; 930 size_t len, auth_len, authx_len, offset, auth_offset, authx_offset; 931 __be32 tmp; 932 int ret; 933 934 gk = rxgk_get_key(conn, NULL); 935 if (IS_ERR(gk)) 936 return PTR_ERR(gk); 937 938 auth_len = 20 + (4 + appdata->len) + 12 + (1 + 4) * 4; 939 authx_len = crypto_krb5_how_much_buffer(gk->krb5, KRB5_ENCRYPT_MODE, 940 auth_len, &auth_offset); 941 len = sizeof(struct rxrpc_wire_header) + 942 8 + (4 + xdr_round_up(gk->key->ticket.len)) + (4 + authx_len); 943 944 response = alloc_skb_with_frags(0, len, 0, &ret, GFP_NOFS); 945 if (!response) 946 goto error; 947 rxrpc_new_skb(response, rxrpc_skb_new_response_rxgk); 948 response->len = len; 949 response->data_len = len; 950 951 ret = rxgk_insert_response_header(conn, gk, response, 0); 952 if (ret < 0) 953 goto error; 954 offset = ret; 955 956 ret = skb_store_bits(response, offset, gk->key->ticket.data, gk->key->ticket.len); 957 if (ret < 0) 958 goto error; 959 offset += gk->key->ticket.len; 960 ret = rxgk_pad_out(response, gk->key->ticket.len, offset); 961 if (ret < 0) 962 goto error; 963 964 authx_offset = offset + ret + 4; /* Leave a gap for the length. */ 965 966 ret = rxgk_construct_authenticator(conn, challenge, appdata, response, 967 authx_offset + auth_offset); 968 if (ret < 0) 969 goto error; 970 auth_len = ret; 971 972 ret = rxgk_encrypt_authenticator(conn, gk, response, 973 authx_offset, authx_len, 974 auth_offset, auth_len); 975 if (ret < 0) 976 goto error; 977 authx_len = ret; 978 979 tmp = htonl(authx_len); 980 ret = skb_store_bits(response, authx_offset - 4, &tmp, 4); 981 if (ret < 0) 982 goto error; 983 984 ret = rxgk_pad_out(response, authx_len, authx_offset + authx_len); 985 if (ret < 0) 986 goto error; 987 len = authx_offset + authx_len + ret; 988 989 if (len != response->len) { 990 response->len = len; 991 response->data_len = len; 992 } 993 994 csp = rxrpc_skb(challenge); 995 rsp = rxrpc_skb(response); 996 rsp->resp.len = len; 997 rsp->resp.challenge_serial = csp->hdr.serial; 998 rxrpc_post_response(conn, response); 999 response = NULL; 1000 ret = 0; 1001 1002 error: 1003 rxrpc_free_skb(response, rxrpc_skb_put_response); 1004 rxgk_put(gk); 1005 _leave(" = %d", ret); 1006 return ret; 1007 } 1008 1009 /* 1010 * Respond to a challenge packet. 1011 */ 1012 static int rxgk_respond_to_challenge(struct rxrpc_connection *conn, 1013 struct sk_buff *challenge, 1014 struct krb5_buffer *appdata) 1015 { 1016 _enter("{%d,%x}", conn->debug_id, key_serial(conn->key)); 1017 1018 if (key_validate(conn->key) < 0) 1019 return rxrpc_abort_conn(conn, NULL, RXGK_EXPIRED, -EPROTO, 1020 rxgk_abort_chall_key_expired); 1021 1022 return rxgk_construct_response(conn, challenge, appdata); 1023 } 1024 1025 static int rxgk_respond_to_challenge_no_appdata(struct rxrpc_connection *conn, 1026 struct sk_buff *challenge) 1027 { 1028 struct krb5_buffer appdata = {}; 1029 1030 return rxgk_respond_to_challenge(conn, challenge, &appdata); 1031 } 1032 1033 /** 1034 * rxgk_kernel_respond_to_challenge - Respond to a challenge with appdata 1035 * @challenge: The challenge to respond to 1036 * @appdata: The application data to include in the RESPONSE authenticator 1037 * 1038 * Allow a kernel application to respond to a CHALLENGE with application data 1039 * to be included in the RxGK RESPONSE Authenticator. 1040 * 1041 * Return: %0 if successful and a negative error code otherwise. 1042 */ 1043 int rxgk_kernel_respond_to_challenge(struct sk_buff *challenge, 1044 struct krb5_buffer *appdata) 1045 { 1046 struct rxrpc_skb_priv *csp = rxrpc_skb(challenge); 1047 1048 return rxgk_respond_to_challenge(csp->chall.conn, challenge, appdata); 1049 } 1050 EXPORT_SYMBOL(rxgk_kernel_respond_to_challenge); 1051 1052 /* 1053 * Parse sendmsg() control message and respond to challenge. We need to see if 1054 * there's an appdata to fish out. 1055 */ 1056 static int rxgk_sendmsg_respond_to_challenge(struct sk_buff *challenge, 1057 struct msghdr *msg) 1058 { 1059 struct krb5_buffer appdata = {}; 1060 struct cmsghdr *cmsg; 1061 1062 for_each_cmsghdr(cmsg, msg) { 1063 if (cmsg->cmsg_level != SOL_RXRPC || 1064 cmsg->cmsg_type != RXRPC_RESP_RXGK_APPDATA) 1065 continue; 1066 if (appdata.data) 1067 return -EINVAL; 1068 appdata.data = CMSG_DATA(cmsg); 1069 appdata.len = cmsg->cmsg_len - sizeof(struct cmsghdr); 1070 } 1071 1072 return rxgk_kernel_respond_to_challenge(challenge, &appdata); 1073 } 1074 1075 /* 1076 * Verify the authenticator. 1077 * 1078 * struct RXGK_Authenticator { 1079 * opaque nonce[20]; 1080 * opaque appdata<>; 1081 * RXGK_Level level; 1082 * unsigned int epoch; 1083 * unsigned int cid; 1084 * unsigned int call_numbers<>; 1085 * }; 1086 */ 1087 static int rxgk_verify_authenticator(struct rxrpc_connection *conn, 1088 const struct krb5_enctype *krb5, 1089 struct sk_buff *skb, 1090 void *auth, unsigned int auth_len) 1091 { 1092 __be32 *p = auth, *end = auth + auth_len; 1093 u32 app_len, call_count, level, epoch, cid, i; 1094 1095 _enter(""); 1096 1097 if ((end - p) * sizeof(__be32) < 24) 1098 return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO, 1099 rxgk_abort_resp_short_auth); 1100 if (memcmp(p, conn->rxgk.nonce, 20) != 0) 1101 return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO, 1102 rxgk_abort_resp_bad_nonce); 1103 p += 20 / sizeof(__be32); 1104 1105 app_len = ntohl(*p++); 1106 if (app_len > (end - p) * sizeof(__be32)) 1107 return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO, 1108 rxgk_abort_resp_short_applen); 1109 1110 p += xdr_round_up(app_len) / sizeof(__be32); 1111 if (end - p < 4) 1112 return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO, 1113 rxgk_abort_resp_short_auth); 1114 1115 level = ntohl(*p++); 1116 epoch = ntohl(*p++); 1117 cid = ntohl(*p++); 1118 call_count = ntohl(*p++); 1119 1120 if (level != conn->security_level || 1121 epoch != conn->proto.epoch || 1122 cid != conn->proto.cid || 1123 call_count > 4) 1124 return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO, 1125 rxgk_abort_resp_bad_param); 1126 1127 if (end - p < call_count) 1128 return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO, 1129 rxgk_abort_resp_short_call_list); 1130 1131 for (i = 0; i < call_count; i++) { 1132 u32 call_id = ntohl(*p++); 1133 1134 if (call_id > INT_MAX) 1135 return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO, 1136 rxgk_abort_resp_bad_callid); 1137 1138 if (call_id < conn->channels[i].call_counter) 1139 return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO, 1140 rxgk_abort_resp_call_ctr); 1141 1142 if (call_id > conn->channels[i].call_counter) { 1143 if (conn->channels[i].call) 1144 return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO, 1145 rxgk_abort_resp_call_state); 1146 1147 conn->channels[i].call_counter = call_id; 1148 } 1149 } 1150 1151 _leave(" = 0"); 1152 return 0; 1153 } 1154 1155 /* 1156 * Verify a response. 1157 * 1158 * struct RXGK_Response { 1159 * rxgkTime start_time; 1160 * RXGK_Data token; 1161 * opaque authenticator<RXGK_MAXAUTHENTICATOR> 1162 * }; 1163 */ 1164 static int rxgk_verify_response(struct rxrpc_connection *conn, 1165 struct sk_buff *skb, 1166 void *buffer, unsigned int len) 1167 { 1168 const struct krb5_enctype *krb5; 1169 struct rxrpc_key_token *token; 1170 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 1171 struct rxgk_response *rhdr; 1172 struct rxgk_context *gk; 1173 struct key *key = NULL; 1174 unsigned int resp_token_len, auth_len; 1175 void *resp_token, *auth; 1176 __be32 xauth_len; 1177 int ret, ec; 1178 1179 _enter("{%d}", conn->debug_id); 1180 1181 /* Parse the RXGK_Response object */ 1182 if (len < sizeof(*rhdr) + sizeof(__be32)) 1183 goto short_packet; 1184 rhdr = buffer; 1185 buffer += sizeof(*rhdr); 1186 len -= sizeof(*rhdr); 1187 1188 resp_token = buffer; 1189 resp_token_len = ntohl(rhdr->token_len); 1190 if (resp_token_len > len || 1191 xdr_round_up(resp_token_len) + sizeof(__be32) > len) 1192 goto short_packet; 1193 1194 trace_rxrpc_rx_response(conn, sp->hdr.serial, 0, sp->hdr.cksum, resp_token_len); 1195 1196 buffer += xdr_round_up(resp_token_len); 1197 len -= xdr_round_up(resp_token_len); 1198 1199 xauth_len = *(__be32 *)buffer; 1200 buffer += sizeof(xauth_len); 1201 len -= sizeof(xauth_len); 1202 1203 auth = buffer; 1204 auth_len = ntohl(xauth_len); 1205 if (auth_len > len) 1206 goto short_packet; 1207 if (auth_len & 3) 1208 goto inconsistent; 1209 if (auth_len < 20 + 9 * 4) 1210 goto auth_too_short; 1211 1212 /* We need to extract and decrypt the token and instantiate a session 1213 * key for it. This bit, however, is application-specific. If 1214 * possible, we use a default parser, but we might end up bumping this 1215 * to the app to deal with - which might mean a round trip to 1216 * userspace. 1217 */ 1218 ret = rxgk_extract_token(conn, skb, resp_token, resp_token_len, &key); 1219 if (ret < 0) 1220 goto out; 1221 1222 /* We now have a key instantiated from the decrypted ticket. We can 1223 * pass this to the application so that they can parse the ticket 1224 * content and we can use the session key it contains to derive the 1225 * keys we need. 1226 * 1227 * Note that we have to switch enctype at this point as the enctype of 1228 * the ticket doesn't necessarily match that of the transport. 1229 */ 1230 token = key->payload.data[0]; 1231 conn->security_level = token->rxgk->level; 1232 conn->rxgk.start_time = __be64_to_cpu(rhdr->start_time); 1233 1234 gk = rxgk_generate_transport_key(conn, token->rxgk, sp->hdr.cksum, GFP_NOFS); 1235 if (IS_ERR(gk)) { 1236 ret = PTR_ERR(gk); 1237 goto cant_get_token; 1238 } 1239 1240 krb5 = gk->krb5; 1241 1242 trace_rxrpc_rx_response(conn, sp->hdr.serial, krb5->etype, sp->hdr.cksum, 1243 resp_token_len); 1244 1245 /* Decrypt, parse and verify the authenticator. */ 1246 ret = rxgk_decrypt(krb5, gk->resp_enc, &auth, &auth_len, &ec); 1247 if (ret < 0) { 1248 rxrpc_abort_conn(conn, skb, RXGK_SEALEDINCON, ret, 1249 rxgk_abort_resp_auth_dec); 1250 goto out_gk; 1251 } 1252 1253 ret = rxgk_verify_authenticator(conn, krb5, skb, auth, auth_len); 1254 if (ret < 0) 1255 goto out_gk; 1256 1257 conn->key = key; 1258 key = NULL; 1259 ret = 0; 1260 out_gk: 1261 rxgk_put(gk); 1262 out: 1263 key_put(key); 1264 _leave(" = %d", ret); 1265 return ret; 1266 1267 inconsistent: 1268 ret = rxrpc_abort_conn(conn, skb, RXGK_INCONSISTENCY, -EPROTO, 1269 rxgk_abort_resp_xdr_align); 1270 goto out; 1271 auth_too_short: 1272 ret = rxrpc_abort_conn(conn, skb, RXGK_PACKETSHORT, -EPROTO, 1273 rxgk_abort_resp_short_auth); 1274 goto out; 1275 short_packet: 1276 ret = rxrpc_abort_conn(conn, skb, RXGK_PACKETSHORT, -EPROTO, 1277 rxgk_abort_resp_short_packet); 1278 goto out; 1279 1280 cant_get_token: 1281 switch (ret) { 1282 case -ENOMEM: 1283 goto temporary_error; 1284 case -EINVAL: 1285 ret = rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EKEYREJECTED, 1286 rxgk_abort_resp_internal_error); 1287 goto out; 1288 case -ENOPKG: 1289 ret = rxrpc_abort_conn(conn, skb, KRB5_PROG_KEYTYPE_NOSUPP, 1290 -EKEYREJECTED, rxgk_abort_resp_nopkg); 1291 goto out; 1292 } 1293 1294 temporary_error: 1295 /* Ignore the response packet if we got a temporary error such as 1296 * ENOMEM. We just want to send the challenge again. Note that we 1297 * also come out this way if the ticket decryption fails. 1298 */ 1299 goto out; 1300 } 1301 1302 /* 1303 * clear the connection security 1304 */ 1305 static void rxgk_clear(struct rxrpc_connection *conn) 1306 { 1307 int i; 1308 1309 for (i = 0; i < ARRAY_SIZE(conn->rxgk.keys); i++) 1310 rxgk_put(conn->rxgk.keys[i]); 1311 } 1312 1313 /* 1314 * Initialise the RxGK security service. 1315 */ 1316 static int rxgk_init(void) 1317 { 1318 return 0; 1319 } 1320 1321 /* 1322 * Clean up the RxGK security service. 1323 */ 1324 static void rxgk_exit(void) 1325 { 1326 } 1327 1328 /* 1329 * RxRPC YFS GSSAPI-based security 1330 */ 1331 const struct rxrpc_security rxgk_yfs = { 1332 .name = "yfs-rxgk", 1333 .security_index = RXRPC_SECURITY_YFS_RXGK, 1334 .no_key_abort = RXGK_NOTAUTH, 1335 .init = rxgk_init, 1336 .exit = rxgk_exit, 1337 .preparse_server_key = rxgk_preparse_server_key, 1338 .free_preparse_server_key = rxgk_free_preparse_server_key, 1339 .destroy_server_key = rxgk_destroy_server_key, 1340 .describe_server_key = rxgk_describe_server_key, 1341 .init_connection_security = rxgk_init_connection_security, 1342 .alloc_txbuf = rxgk_alloc_txbuf, 1343 .secure_packet = rxgk_secure_packet, 1344 .verify_packet = rxgk_verify_packet, 1345 .free_call_crypto = rxgk_free_call_crypto, 1346 .issue_challenge = rxgk_issue_challenge, 1347 .validate_challenge = rxgk_validate_challenge, 1348 .challenge_to_recvmsg = rxgk_challenge_to_recvmsg, 1349 .sendmsg_respond_to_challenge = rxgk_sendmsg_respond_to_challenge, 1350 .respond_to_challenge = rxgk_respond_to_challenge_no_appdata, 1351 .verify_response = rxgk_verify_response, 1352 .clear = rxgk_clear, 1353 .default_decode_ticket = rxgk_yfs_decode_ticket, 1354 }; 1355