1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (c) 2022 Paulo Alcantara <palcantara@suse.de> 4 */ 5 6 #include "cifsproto.h" 7 #include "cifs_debug.h" 8 #include "dns_resolve.h" 9 #include "fs_context.h" 10 #include "dfs.h" 11 12 /** 13 * dfs_parse_target_referral - set fs context for dfs target referral 14 * 15 * @full_path: full path in UNC format. 16 * @ref: dfs referral pointer. 17 * @ctx: smb3 fs context pointer. 18 * 19 * Return zero if dfs referral was parsed correctly, otherwise non-zero. 20 */ 21 int dfs_parse_target_referral(const char *full_path, const struct dfs_info3_param *ref, 22 struct smb3_fs_context *ctx) 23 { 24 int rc; 25 const char *prepath = NULL; 26 char *path; 27 28 if (!full_path || !*full_path || !ref || !ctx) 29 return -EINVAL; 30 31 if (WARN_ON_ONCE(!ref->node_name || ref->path_consumed < 0)) 32 return -EINVAL; 33 34 if (strlen(full_path) - ref->path_consumed) { 35 prepath = full_path + ref->path_consumed; 36 /* skip initial delimiter */ 37 if (*prepath == '/' || *prepath == '\\') 38 prepath++; 39 } 40 41 path = cifs_build_devname(ref->node_name, prepath); 42 if (IS_ERR(path)) 43 return PTR_ERR(path); 44 45 rc = smb3_parse_devname(path, ctx); 46 if (rc) 47 goto out; 48 49 rc = dns_resolve_server_name_to_ip(path, (struct sockaddr *)&ctx->dstaddr, NULL); 50 51 out: 52 kfree(path); 53 return rc; 54 } 55 56 static int get_session(struct cifs_mount_ctx *mnt_ctx, const char *full_path) 57 { 58 struct smb3_fs_context *ctx = mnt_ctx->fs_ctx; 59 int rc; 60 61 ctx->leaf_fullpath = (char *)full_path; 62 rc = cifs_mount_get_session(mnt_ctx); 63 ctx->leaf_fullpath = NULL; 64 65 return rc; 66 } 67 68 /* 69 * Track individual DFS referral servers used by new DFS mount. 70 * 71 * On success, their lifetime will be shared by final tcon (dfs_ses_list). 72 * Otherwise, they will be put by dfs_put_root_smb_sessions() in cifs_mount(). 73 */ 74 static int add_root_smb_session(struct cifs_mount_ctx *mnt_ctx) 75 { 76 struct smb3_fs_context *ctx = mnt_ctx->fs_ctx; 77 struct dfs_root_ses *root_ses; 78 struct cifs_ses *ses = mnt_ctx->ses; 79 80 if (ses) { 81 root_ses = kmalloc(sizeof(*root_ses), GFP_KERNEL); 82 if (!root_ses) 83 return -ENOMEM; 84 85 INIT_LIST_HEAD(&root_ses->list); 86 87 spin_lock(&cifs_tcp_ses_lock); 88 cifs_smb_ses_inc_refcount(ses); 89 spin_unlock(&cifs_tcp_ses_lock); 90 root_ses->ses = ses; 91 list_add_tail(&root_ses->list, &mnt_ctx->dfs_ses_list); 92 } 93 /* Select new DFS referral server so that new referrals go through it */ 94 ctx->dfs_root_ses = ses; 95 return 0; 96 } 97 98 static inline int parse_dfs_target(struct smb3_fs_context *ctx, 99 struct dfs_ref_walk *rw, 100 struct dfs_info3_param *tgt) 101 { 102 int rc; 103 const char *fpath = ref_walk_fpath(rw) + 1; 104 105 rc = ref_walk_get_tgt(rw, tgt); 106 if (!rc) 107 rc = dfs_parse_target_referral(fpath, tgt, ctx); 108 return rc; 109 } 110 111 static int set_ref_paths(struct cifs_mount_ctx *mnt_ctx, 112 struct dfs_info3_param *tgt, 113 struct dfs_ref_walk *rw) 114 { 115 struct smb3_fs_context *ctx = mnt_ctx->fs_ctx; 116 struct cifs_sb_info *cifs_sb = mnt_ctx->cifs_sb; 117 char *ref_path, *full_path; 118 int rc; 119 120 full_path = smb3_fs_context_fullpath(ctx, CIFS_DIR_SEP(cifs_sb)); 121 if (IS_ERR(full_path)) 122 return PTR_ERR(full_path); 123 124 if (!tgt || (tgt->server_type == DFS_TYPE_LINK && 125 DFS_INTERLINK(tgt->flags))) 126 ref_path = dfs_get_path(cifs_sb, ctx->UNC); 127 else 128 ref_path = dfs_get_path(cifs_sb, full_path); 129 if (IS_ERR(ref_path)) { 130 rc = PTR_ERR(ref_path); 131 kfree(full_path); 132 return rc; 133 } 134 ref_walk_path(rw) = ref_path; 135 ref_walk_fpath(rw) = full_path; 136 return 0; 137 } 138 139 static int __dfs_referral_walk(struct cifs_mount_ctx *mnt_ctx, 140 struct dfs_ref_walk *rw) 141 { 142 struct smb3_fs_context *ctx = mnt_ctx->fs_ctx; 143 struct dfs_info3_param tgt = {}; 144 bool is_refsrv; 145 int rc = -ENOENT; 146 147 again: 148 do { 149 if (ref_walk_empty(rw)) { 150 rc = dfs_get_referral(mnt_ctx, ref_walk_path(rw) + 1, 151 NULL, ref_walk_tl(rw)); 152 if (rc) { 153 rc = cifs_mount_get_tcon(mnt_ctx); 154 if (!rc) 155 rc = cifs_is_path_remote(mnt_ctx); 156 continue; 157 } 158 if (!ref_walk_num_tgts(rw)) { 159 rc = -ENOENT; 160 continue; 161 } 162 } 163 164 while (ref_walk_next_tgt(rw)) { 165 rc = parse_dfs_target(ctx, rw, &tgt); 166 if (rc) 167 continue; 168 169 cifs_mount_put_conns(mnt_ctx); 170 rc = get_session(mnt_ctx, ref_walk_path(rw)); 171 if (rc) 172 continue; 173 174 is_refsrv = tgt.server_type == DFS_TYPE_ROOT || 175 DFS_INTERLINK(tgt.flags); 176 ref_walk_set_tgt_hint(rw); 177 178 if (tgt.flags & DFSREF_STORAGE_SERVER) { 179 rc = cifs_mount_get_tcon(mnt_ctx); 180 if (!rc) 181 rc = cifs_is_path_remote(mnt_ctx); 182 if (!rc) 183 break; 184 if (rc != -EREMOTE) 185 continue; 186 } 187 188 if (is_refsrv) { 189 rc = add_root_smb_session(mnt_ctx); 190 if (rc) 191 goto out; 192 } 193 194 rc = ref_walk_advance(rw); 195 if (!rc) { 196 rc = set_ref_paths(mnt_ctx, &tgt, rw); 197 if (!rc) { 198 rc = -EREMOTE; 199 goto again; 200 } 201 } 202 if (rc != -ELOOP) 203 goto out; 204 } 205 } while (rc && ref_walk_descend(rw)); 206 207 out: 208 free_dfs_info_param(&tgt); 209 return rc; 210 } 211 212 static int dfs_referral_walk(struct cifs_mount_ctx *mnt_ctx) 213 { 214 struct dfs_ref_walk *rw; 215 int rc; 216 217 rw = ref_walk_alloc(); 218 if (IS_ERR(rw)) 219 return PTR_ERR(rw); 220 221 ref_walk_init(rw); 222 rc = set_ref_paths(mnt_ctx, NULL, rw); 223 if (!rc) 224 rc = __dfs_referral_walk(mnt_ctx, rw); 225 ref_walk_free(rw); 226 return rc; 227 } 228 229 static int __dfs_mount_share(struct cifs_mount_ctx *mnt_ctx) 230 { 231 struct cifs_sb_info *cifs_sb = mnt_ctx->cifs_sb; 232 struct smb3_fs_context *ctx = mnt_ctx->fs_ctx; 233 struct cifs_tcon *tcon; 234 char *origin_fullpath; 235 int rc; 236 237 origin_fullpath = dfs_get_path(cifs_sb, ctx->source); 238 if (IS_ERR(origin_fullpath)) 239 return PTR_ERR(origin_fullpath); 240 241 rc = dfs_referral_walk(mnt_ctx); 242 if (rc) 243 goto out; 244 245 tcon = mnt_ctx->tcon; 246 spin_lock(&tcon->tc_lock); 247 if (!tcon->origin_fullpath) { 248 tcon->origin_fullpath = origin_fullpath; 249 origin_fullpath = NULL; 250 } 251 spin_unlock(&tcon->tc_lock); 252 253 if (list_empty(&tcon->dfs_ses_list)) { 254 list_replace_init(&mnt_ctx->dfs_ses_list, &tcon->dfs_ses_list); 255 queue_delayed_work(dfscache_wq, &tcon->dfs_cache_work, 256 dfs_cache_get_ttl() * HZ); 257 } else { 258 dfs_put_root_smb_sessions(&mnt_ctx->dfs_ses_list); 259 } 260 261 out: 262 kfree(origin_fullpath); 263 return rc; 264 } 265 266 /* 267 * If @ctx->dfs_automount, then update @ctx->dstaddr earlier with the DFS root 268 * server from where we'll start following any referrals. Otherwise rely on the 269 * value provided by mount(2) as the user might not have dns_resolver key set up 270 * and therefore failing to upcall to resolve UNC hostname under @ctx->source. 271 */ 272 static int update_fs_context_dstaddr(struct smb3_fs_context *ctx) 273 { 274 struct sockaddr *addr = (struct sockaddr *)&ctx->dstaddr; 275 int rc = 0; 276 277 if (!ctx->nodfs && ctx->dfs_automount) { 278 rc = dns_resolve_server_name_to_ip(ctx->source, addr, NULL); 279 if (!rc) 280 cifs_set_port(addr, ctx->port); 281 ctx->dfs_automount = false; 282 } 283 return rc; 284 } 285 286 int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs) 287 { 288 struct smb3_fs_context *ctx = mnt_ctx->fs_ctx; 289 bool nodfs = ctx->nodfs; 290 int rc; 291 292 rc = update_fs_context_dstaddr(ctx); 293 if (rc) 294 return rc; 295 296 *isdfs = false; 297 rc = get_session(mnt_ctx, NULL); 298 if (rc) 299 return rc; 300 301 ctx->dfs_root_ses = mnt_ctx->ses; 302 /* 303 * If called with 'nodfs' mount option, then skip DFS resolving. Otherwise unconditionally 304 * try to get an DFS referral (even cached) to determine whether it is an DFS mount. 305 * 306 * Skip prefix path to provide support for DFS referrals from w2k8 servers which don't seem 307 * to respond with PATH_NOT_COVERED to requests that include the prefix. 308 */ 309 if (!nodfs) { 310 rc = dfs_get_referral(mnt_ctx, ctx->UNC + 1, NULL, NULL); 311 if (rc) { 312 cifs_dbg(FYI, "%s: no dfs referral for %s: %d\n", 313 __func__, ctx->UNC + 1, rc); 314 cifs_dbg(FYI, "%s: assuming non-dfs mount...\n", __func__); 315 nodfs = true; 316 } 317 } 318 if (nodfs) { 319 rc = cifs_mount_get_tcon(mnt_ctx); 320 if (!rc) 321 rc = cifs_is_path_remote(mnt_ctx); 322 return rc; 323 } 324 325 *isdfs = true; 326 add_root_smb_session(mnt_ctx); 327 return __dfs_mount_share(mnt_ctx); 328 } 329 330 /* Update dfs referral path of superblock */ 331 static int update_server_fullpath(struct TCP_Server_Info *server, struct cifs_sb_info *cifs_sb, 332 const char *target) 333 { 334 int rc = 0; 335 size_t len = strlen(target); 336 char *refpath, *npath; 337 338 if (unlikely(len < 2 || *target != '\\')) 339 return -EINVAL; 340 341 if (target[1] == '\\') { 342 len += 1; 343 refpath = kmalloc(len, GFP_KERNEL); 344 if (!refpath) 345 return -ENOMEM; 346 347 scnprintf(refpath, len, "%s", target); 348 } else { 349 len += sizeof("\\"); 350 refpath = kmalloc(len, GFP_KERNEL); 351 if (!refpath) 352 return -ENOMEM; 353 354 scnprintf(refpath, len, "\\%s", target); 355 } 356 357 npath = dfs_cache_canonical_path(refpath, cifs_sb->local_nls, cifs_remap(cifs_sb)); 358 kfree(refpath); 359 360 if (IS_ERR(npath)) { 361 rc = PTR_ERR(npath); 362 } else { 363 mutex_lock(&server->refpath_lock); 364 spin_lock(&server->srv_lock); 365 kfree(server->leaf_fullpath); 366 server->leaf_fullpath = npath; 367 spin_unlock(&server->srv_lock); 368 mutex_unlock(&server->refpath_lock); 369 } 370 return rc; 371 } 372 373 static int target_share_matches_server(struct TCP_Server_Info *server, char *share, 374 bool *target_match) 375 { 376 int rc = 0; 377 const char *dfs_host; 378 size_t dfs_host_len; 379 380 *target_match = true; 381 extract_unc_hostname(share, &dfs_host, &dfs_host_len); 382 383 /* Check if hostnames or addresses match */ 384 cifs_server_lock(server); 385 if (dfs_host_len != strlen(server->hostname) || 386 strncasecmp(dfs_host, server->hostname, dfs_host_len)) { 387 cifs_dbg(FYI, "%s: %.*s doesn't match %s\n", __func__, 388 (int)dfs_host_len, dfs_host, server->hostname); 389 rc = match_target_ip(server, dfs_host, dfs_host_len, target_match); 390 if (rc) 391 cifs_dbg(VFS, "%s: failed to match target ip: %d\n", __func__, rc); 392 } 393 cifs_server_unlock(server); 394 return rc; 395 } 396 397 static void __tree_connect_ipc(const unsigned int xid, char *tree, 398 struct cifs_sb_info *cifs_sb, 399 struct cifs_ses *ses) 400 { 401 struct TCP_Server_Info *server = ses->server; 402 struct cifs_tcon *tcon = ses->tcon_ipc; 403 int rc; 404 405 spin_lock(&ses->ses_lock); 406 spin_lock(&ses->chan_lock); 407 if (cifs_chan_needs_reconnect(ses, server) || 408 ses->ses_status != SES_GOOD) { 409 spin_unlock(&ses->chan_lock); 410 spin_unlock(&ses->ses_lock); 411 cifs_server_dbg(FYI, "%s: skipping ipc reconnect due to disconnected ses\n", 412 __func__); 413 return; 414 } 415 spin_unlock(&ses->chan_lock); 416 spin_unlock(&ses->ses_lock); 417 418 cifs_server_lock(server); 419 scnprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$", server->hostname); 420 cifs_server_unlock(server); 421 422 rc = server->ops->tree_connect(xid, ses, tree, tcon, 423 cifs_sb->local_nls); 424 cifs_server_dbg(FYI, "%s: tree_reconnect %s: %d\n", __func__, tree, rc); 425 spin_lock(&tcon->tc_lock); 426 if (rc) { 427 tcon->status = TID_NEED_TCON; 428 } else { 429 tcon->status = TID_GOOD; 430 tcon->need_reconnect = false; 431 } 432 spin_unlock(&tcon->tc_lock); 433 } 434 435 static void tree_connect_ipc(const unsigned int xid, char *tree, 436 struct cifs_sb_info *cifs_sb, 437 struct cifs_tcon *tcon) 438 { 439 struct cifs_ses *ses = tcon->ses; 440 441 __tree_connect_ipc(xid, tree, cifs_sb, ses); 442 __tree_connect_ipc(xid, tree, cifs_sb, CIFS_DFS_ROOT_SES(ses)); 443 } 444 445 static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *tcon, 446 struct cifs_sb_info *cifs_sb, char *tree, bool islink, 447 struct dfs_cache_tgt_list *tl) 448 { 449 int rc; 450 struct TCP_Server_Info *server = tcon->ses->server; 451 const struct smb_version_operations *ops = server->ops; 452 struct cifs_ses *root_ses = CIFS_DFS_ROOT_SES(tcon->ses); 453 char *share = NULL, *prefix = NULL; 454 struct dfs_cache_tgt_iterator *tit; 455 bool target_match; 456 457 tit = dfs_cache_get_tgt_iterator(tl); 458 if (!tit) { 459 rc = -ENOENT; 460 goto out; 461 } 462 463 /* Try to tree connect to all dfs targets */ 464 for (; tit; tit = dfs_cache_get_next_tgt(tl, tit)) { 465 const char *target = dfs_cache_get_tgt_name(tit); 466 DFS_CACHE_TGT_LIST(ntl); 467 468 kfree(share); 469 kfree(prefix); 470 share = prefix = NULL; 471 472 /* Check if share matches with tcp ses */ 473 rc = dfs_cache_get_tgt_share(server->leaf_fullpath + 1, tit, &share, &prefix); 474 if (rc) { 475 cifs_dbg(VFS, "%s: failed to parse target share: %d\n", __func__, rc); 476 break; 477 } 478 479 rc = target_share_matches_server(server, share, &target_match); 480 if (rc) 481 break; 482 if (!target_match) { 483 rc = -EHOSTUNREACH; 484 continue; 485 } 486 487 dfs_cache_noreq_update_tgthint(server->leaf_fullpath + 1, tit); 488 tree_connect_ipc(xid, tree, cifs_sb, tcon); 489 490 scnprintf(tree, MAX_TREE_SIZE, "\\%s", share); 491 if (!islink) { 492 rc = ops->tree_connect(xid, tcon->ses, tree, tcon, cifs_sb->local_nls); 493 break; 494 } 495 496 /* 497 * If no dfs referrals were returned from link target, then just do a TREE_CONNECT 498 * to it. Otherwise, cache the dfs referral and then mark current tcp ses for 499 * reconnect so either the demultiplex thread or the echo worker will reconnect to 500 * newly resolved target. 501 */ 502 if (dfs_cache_find(xid, root_ses, cifs_sb->local_nls, cifs_remap(cifs_sb), target, 503 NULL, &ntl)) { 504 rc = ops->tree_connect(xid, tcon->ses, tree, tcon, cifs_sb->local_nls); 505 if (rc) 506 continue; 507 508 rc = cifs_update_super_prepath(cifs_sb, prefix); 509 } else { 510 /* Target is another dfs share */ 511 rc = update_server_fullpath(server, cifs_sb, target); 512 dfs_cache_free_tgts(tl); 513 514 if (!rc) { 515 rc = -EREMOTE; 516 list_replace_init(&ntl.tl_list, &tl->tl_list); 517 } else 518 dfs_cache_free_tgts(&ntl); 519 } 520 break; 521 } 522 523 out: 524 kfree(share); 525 kfree(prefix); 526 527 return rc; 528 } 529 530 static int tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *tcon, 531 struct cifs_sb_info *cifs_sb, char *tree, bool islink, 532 struct dfs_cache_tgt_list *tl) 533 { 534 int rc; 535 int num_links = 0; 536 struct TCP_Server_Info *server = tcon->ses->server; 537 char *old_fullpath = server->leaf_fullpath; 538 539 do { 540 rc = __tree_connect_dfs_target(xid, tcon, cifs_sb, tree, islink, tl); 541 if (!rc || rc != -EREMOTE) 542 break; 543 } while (rc = -ELOOP, ++num_links < MAX_NESTED_LINKS); 544 /* 545 * If we couldn't tree connect to any targets from last referral path, then 546 * retry it from newly resolved dfs referral. 547 */ 548 if (rc && server->leaf_fullpath != old_fullpath) 549 cifs_signal_cifsd_for_reconnect(server, true); 550 551 dfs_cache_free_tgts(tl); 552 return rc; 553 } 554 555 int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const struct nls_table *nlsc) 556 { 557 int rc; 558 struct TCP_Server_Info *server = tcon->ses->server; 559 const struct smb_version_operations *ops = server->ops; 560 DFS_CACHE_TGT_LIST(tl); 561 struct cifs_sb_info *cifs_sb = NULL; 562 struct super_block *sb = NULL; 563 struct dfs_info3_param ref = {0}; 564 char *tree; 565 566 /* only send once per connect */ 567 spin_lock(&tcon->tc_lock); 568 if (tcon->status == TID_GOOD) { 569 spin_unlock(&tcon->tc_lock); 570 return 0; 571 } 572 573 if (tcon->status != TID_NEW && 574 tcon->status != TID_NEED_TCON) { 575 spin_unlock(&tcon->tc_lock); 576 return -EHOSTDOWN; 577 } 578 579 tcon->status = TID_IN_TCON; 580 spin_unlock(&tcon->tc_lock); 581 582 tree = kzalloc(MAX_TREE_SIZE, GFP_KERNEL); 583 if (!tree) { 584 rc = -ENOMEM; 585 goto out; 586 } 587 588 if (tcon->ipc) { 589 cifs_server_lock(server); 590 scnprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$", server->hostname); 591 cifs_server_unlock(server); 592 rc = ops->tree_connect(xid, tcon->ses, tree, tcon, nlsc); 593 goto out; 594 } 595 596 sb = cifs_get_dfs_tcon_super(tcon); 597 if (!IS_ERR(sb)) 598 cifs_sb = CIFS_SB(sb); 599 600 /* 601 * Tree connect to last share in @tcon->tree_name whether dfs super or 602 * cached dfs referral was not found. 603 */ 604 if (!cifs_sb || !server->leaf_fullpath || 605 dfs_cache_noreq_find(server->leaf_fullpath + 1, &ref, &tl)) { 606 rc = ops->tree_connect(xid, tcon->ses, tcon->tree_name, tcon, 607 cifs_sb ? cifs_sb->local_nls : nlsc); 608 goto out; 609 } 610 611 rc = tree_connect_dfs_target(xid, tcon, cifs_sb, tree, ref.server_type == DFS_TYPE_LINK, 612 &tl); 613 free_dfs_info_param(&ref); 614 615 out: 616 kfree(tree); 617 cifs_put_tcp_super(sb); 618 619 if (rc) { 620 spin_lock(&tcon->tc_lock); 621 if (tcon->status == TID_IN_TCON) 622 tcon->status = TID_NEED_TCON; 623 spin_unlock(&tcon->tc_lock); 624 } else { 625 spin_lock(&tcon->tc_lock); 626 if (tcon->status == TID_IN_TCON) 627 tcon->status = TID_GOOD; 628 spin_unlock(&tcon->tc_lock); 629 tcon->need_reconnect = false; 630 } 631 632 return rc; 633 } 634