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 * Get an active reference of @ses so that next call to cifs_put_tcon() won't 70 * release it as any new DFS referrals must go through its IPC tcon. 71 */ 72 static void add_root_smb_session(struct cifs_mount_ctx *mnt_ctx) 73 { 74 struct smb3_fs_context *ctx = mnt_ctx->fs_ctx; 75 struct cifs_ses *ses = mnt_ctx->ses; 76 77 if (ses) { 78 spin_lock(&cifs_tcp_ses_lock); 79 cifs_smb_ses_inc_refcount(ses); 80 spin_unlock(&cifs_tcp_ses_lock); 81 } 82 ctx->dfs_root_ses = ses; 83 } 84 85 static inline int parse_dfs_target(struct smb3_fs_context *ctx, 86 struct dfs_ref_walk *rw, 87 struct dfs_info3_param *tgt) 88 { 89 int rc; 90 const char *fpath = ref_walk_fpath(rw) + 1; 91 92 rc = ref_walk_get_tgt(rw, tgt); 93 if (!rc) 94 rc = dfs_parse_target_referral(fpath, tgt, ctx); 95 return rc; 96 } 97 98 static int set_ref_paths(struct cifs_mount_ctx *mnt_ctx, 99 struct dfs_info3_param *tgt, 100 struct dfs_ref_walk *rw) 101 { 102 struct smb3_fs_context *ctx = mnt_ctx->fs_ctx; 103 struct cifs_sb_info *cifs_sb = mnt_ctx->cifs_sb; 104 char *ref_path, *full_path; 105 int rc; 106 107 full_path = smb3_fs_context_fullpath(ctx, CIFS_DIR_SEP(cifs_sb)); 108 if (IS_ERR(full_path)) 109 return PTR_ERR(full_path); 110 111 if (!tgt || (tgt->server_type == DFS_TYPE_LINK && 112 DFS_INTERLINK(tgt->flags))) 113 ref_path = dfs_get_path(cifs_sb, ctx->UNC); 114 else 115 ref_path = dfs_get_path(cifs_sb, full_path); 116 if (IS_ERR(ref_path)) { 117 rc = PTR_ERR(ref_path); 118 kfree(full_path); 119 return rc; 120 } 121 ref_walk_path(rw) = ref_path; 122 ref_walk_fpath(rw) = full_path; 123 return 0; 124 } 125 126 static int __dfs_referral_walk(struct cifs_mount_ctx *mnt_ctx, 127 struct dfs_ref_walk *rw) 128 { 129 struct smb3_fs_context *ctx = mnt_ctx->fs_ctx; 130 struct dfs_info3_param tgt = {}; 131 bool is_refsrv; 132 int rc = -ENOENT; 133 134 again: 135 do { 136 if (ref_walk_empty(rw)) { 137 rc = dfs_get_referral(mnt_ctx, ref_walk_path(rw) + 1, 138 NULL, ref_walk_tl(rw)); 139 if (rc) { 140 rc = cifs_mount_get_tcon(mnt_ctx); 141 if (!rc) 142 rc = cifs_is_path_remote(mnt_ctx); 143 continue; 144 } 145 if (!ref_walk_num_tgts(rw)) { 146 rc = -ENOENT; 147 continue; 148 } 149 } 150 151 while (ref_walk_next_tgt(rw)) { 152 rc = parse_dfs_target(ctx, rw, &tgt); 153 if (rc) 154 continue; 155 156 cifs_mount_put_conns(mnt_ctx); 157 rc = get_session(mnt_ctx, ref_walk_path(rw)); 158 if (rc) 159 continue; 160 161 is_refsrv = tgt.server_type == DFS_TYPE_ROOT || 162 DFS_INTERLINK(tgt.flags); 163 ref_walk_set_tgt_hint(rw); 164 165 if (tgt.flags & DFSREF_STORAGE_SERVER) { 166 rc = cifs_mount_get_tcon(mnt_ctx); 167 if (!rc) 168 rc = cifs_is_path_remote(mnt_ctx); 169 if (!rc) 170 break; 171 if (rc != -EREMOTE) 172 continue; 173 } 174 175 if (is_refsrv) 176 add_root_smb_session(mnt_ctx); 177 178 rc = ref_walk_advance(rw); 179 if (!rc) { 180 rc = set_ref_paths(mnt_ctx, &tgt, rw); 181 if (!rc) { 182 rc = -EREMOTE; 183 goto again; 184 } 185 } 186 if (rc != -ELOOP) 187 goto out; 188 } 189 } while (rc && ref_walk_descend(rw)); 190 191 out: 192 free_dfs_info_param(&tgt); 193 return rc; 194 } 195 196 static int dfs_referral_walk(struct cifs_mount_ctx *mnt_ctx) 197 { 198 struct dfs_ref_walk *rw; 199 int rc; 200 201 rw = ref_walk_alloc(); 202 if (IS_ERR(rw)) 203 return PTR_ERR(rw); 204 205 ref_walk_init(rw); 206 rc = set_ref_paths(mnt_ctx, NULL, rw); 207 if (!rc) 208 rc = __dfs_referral_walk(mnt_ctx, rw); 209 ref_walk_free(rw); 210 return rc; 211 } 212 213 static int __dfs_mount_share(struct cifs_mount_ctx *mnt_ctx) 214 { 215 struct cifs_sb_info *cifs_sb = mnt_ctx->cifs_sb; 216 struct smb3_fs_context *ctx = mnt_ctx->fs_ctx; 217 struct cifs_tcon *tcon; 218 char *origin_fullpath; 219 bool new_tcon = true; 220 int rc; 221 222 origin_fullpath = dfs_get_path(cifs_sb, ctx->source); 223 if (IS_ERR(origin_fullpath)) 224 return PTR_ERR(origin_fullpath); 225 226 rc = dfs_referral_walk(mnt_ctx); 227 if (!rc) { 228 /* 229 * Prevent superblock from being created with any missing 230 * connections. 231 */ 232 if (WARN_ON(!mnt_ctx->server)) 233 rc = -EHOSTDOWN; 234 else if (WARN_ON(!mnt_ctx->ses)) 235 rc = -EACCES; 236 else if (WARN_ON(!mnt_ctx->tcon)) 237 rc = -ENOENT; 238 } 239 if (rc) 240 goto out; 241 242 tcon = mnt_ctx->tcon; 243 spin_lock(&tcon->tc_lock); 244 if (!tcon->origin_fullpath) { 245 tcon->origin_fullpath = origin_fullpath; 246 origin_fullpath = NULL; 247 } else { 248 new_tcon = false; 249 } 250 spin_unlock(&tcon->tc_lock); 251 252 if (new_tcon) { 253 queue_delayed_work(dfscache_wq, &tcon->dfs_cache_work, 254 dfs_cache_get_ttl() * HZ); 255 } 256 257 out: 258 kfree(origin_fullpath); 259 return rc; 260 } 261 262 /* 263 * If @ctx->dfs_automount, then update @ctx->dstaddr earlier with the DFS root 264 * server from where we'll start following any referrals. Otherwise rely on the 265 * value provided by mount(2) as the user might not have dns_resolver key set up 266 * and therefore failing to upcall to resolve UNC hostname under @ctx->source. 267 */ 268 static int update_fs_context_dstaddr(struct smb3_fs_context *ctx) 269 { 270 struct sockaddr *addr = (struct sockaddr *)&ctx->dstaddr; 271 int rc = 0; 272 273 if (!ctx->nodfs && ctx->dfs_automount) { 274 rc = dns_resolve_server_name_to_ip(ctx->source, addr, NULL); 275 if (!rc) 276 cifs_set_port(addr, ctx->port); 277 ctx->dfs_automount = false; 278 } 279 return rc; 280 } 281 282 int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs) 283 { 284 struct smb3_fs_context *ctx = mnt_ctx->fs_ctx; 285 bool nodfs = ctx->nodfs; 286 int rc; 287 288 rc = update_fs_context_dstaddr(ctx); 289 if (rc) 290 return rc; 291 292 *isdfs = false; 293 rc = get_session(mnt_ctx, NULL); 294 if (rc) 295 return rc; 296 297 /* 298 * If called with 'nodfs' mount option, then skip DFS resolving. Otherwise unconditionally 299 * try to get an DFS referral (even cached) to determine whether it is an DFS mount. 300 * 301 * Skip prefix path to provide support for DFS referrals from w2k8 servers which don't seem 302 * to respond with PATH_NOT_COVERED to requests that include the prefix. 303 */ 304 if (!nodfs) { 305 rc = dfs_get_referral(mnt_ctx, ctx->UNC + 1, NULL, NULL); 306 if (rc) { 307 cifs_dbg(FYI, "%s: no dfs referral for %s: %d\n", 308 __func__, ctx->UNC + 1, rc); 309 cifs_dbg(FYI, "%s: assuming non-dfs mount...\n", __func__); 310 nodfs = true; 311 } 312 } 313 if (nodfs) { 314 rc = cifs_mount_get_tcon(mnt_ctx); 315 if (!rc) 316 rc = cifs_is_path_remote(mnt_ctx); 317 return rc; 318 } 319 320 *isdfs = true; 321 add_root_smb_session(mnt_ctx); 322 rc = __dfs_mount_share(mnt_ctx); 323 dfs_put_root_smb_sessions(mnt_ctx); 324 return rc; 325 } 326 327 static int target_share_matches_server(struct TCP_Server_Info *server, char *share, 328 bool *target_match) 329 { 330 int rc = 0; 331 const char *dfs_host; 332 size_t dfs_host_len; 333 334 *target_match = true; 335 extract_unc_hostname(share, &dfs_host, &dfs_host_len); 336 337 /* Check if hostnames or addresses match */ 338 cifs_server_lock(server); 339 if (dfs_host_len != strlen(server->hostname) || 340 strncasecmp(dfs_host, server->hostname, dfs_host_len)) { 341 cifs_dbg(FYI, "%s: %.*s doesn't match %s\n", __func__, 342 (int)dfs_host_len, dfs_host, server->hostname); 343 rc = match_target_ip(server, dfs_host, dfs_host_len, target_match); 344 if (rc) 345 cifs_dbg(VFS, "%s: failed to match target ip: %d\n", __func__, rc); 346 } 347 cifs_server_unlock(server); 348 return rc; 349 } 350 351 static int tree_connect_dfs_target(const unsigned int xid, 352 struct cifs_tcon *tcon, 353 struct cifs_sb_info *cifs_sb, 354 char *tree, bool islink, 355 struct dfs_cache_tgt_list *tl) 356 { 357 const struct smb_version_operations *ops = tcon->ses->server->ops; 358 struct TCP_Server_Info *server = tcon->ses->server; 359 struct dfs_cache_tgt_iterator *tit; 360 char *share = NULL, *prefix = NULL; 361 bool target_match; 362 int rc = -ENOENT; 363 364 /* Try to tree connect to all dfs targets */ 365 for (tit = dfs_cache_get_tgt_iterator(tl); 366 tit; tit = dfs_cache_get_next_tgt(tl, tit)) { 367 kfree(share); 368 kfree(prefix); 369 share = prefix = NULL; 370 371 /* Check if share matches with tcp ses */ 372 rc = dfs_cache_get_tgt_share(server->leaf_fullpath + 1, tit, &share, &prefix); 373 if (rc) { 374 cifs_dbg(VFS, "%s: failed to parse target share: %d\n", __func__, rc); 375 break; 376 } 377 378 rc = target_share_matches_server(server, share, &target_match); 379 if (rc) 380 break; 381 if (!target_match) { 382 rc = -EHOSTUNREACH; 383 continue; 384 } 385 386 dfs_cache_noreq_update_tgthint(server->leaf_fullpath + 1, tit); 387 scnprintf(tree, MAX_TREE_SIZE, "\\%s", share); 388 rc = ops->tree_connect(xid, tcon->ses, tree, 389 tcon, tcon->ses->local_nls); 390 if (islink && !rc && cifs_sb) 391 rc = cifs_update_super_prepath(cifs_sb, prefix); 392 break; 393 } 394 395 kfree(share); 396 kfree(prefix); 397 dfs_cache_free_tgts(tl); 398 return rc; 399 } 400 401 int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const struct nls_table *nlsc) 402 { 403 int rc; 404 struct TCP_Server_Info *server = tcon->ses->server; 405 const struct smb_version_operations *ops = server->ops; 406 DFS_CACHE_TGT_LIST(tl); 407 struct cifs_sb_info *cifs_sb = NULL; 408 struct super_block *sb = NULL; 409 struct dfs_info3_param ref = {0}; 410 char *tree; 411 412 /* only send once per connect */ 413 spin_lock(&tcon->tc_lock); 414 415 /* if tcon is marked for needing reconnect, update state */ 416 if (tcon->need_reconnect) 417 tcon->status = TID_NEED_TCON; 418 419 if (tcon->status == TID_GOOD) { 420 spin_unlock(&tcon->tc_lock); 421 return 0; 422 } 423 424 if (tcon->status != TID_NEW && 425 tcon->status != TID_NEED_TCON) { 426 spin_unlock(&tcon->tc_lock); 427 return -EHOSTDOWN; 428 } 429 430 tcon->status = TID_IN_TCON; 431 spin_unlock(&tcon->tc_lock); 432 433 tree = kzalloc(MAX_TREE_SIZE, GFP_KERNEL); 434 if (!tree) { 435 rc = -ENOMEM; 436 goto out; 437 } 438 439 if (tcon->ipc) { 440 cifs_server_lock(server); 441 scnprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$", server->hostname); 442 cifs_server_unlock(server); 443 rc = ops->tree_connect(xid, tcon->ses, tree, tcon, nlsc); 444 goto out; 445 } 446 447 sb = cifs_get_dfs_tcon_super(tcon); 448 if (!IS_ERR(sb)) 449 cifs_sb = CIFS_SB(sb); 450 451 /* Tree connect to last share in @tcon->tree_name if no DFS referral */ 452 if (!server->leaf_fullpath || 453 dfs_cache_noreq_find(server->leaf_fullpath + 1, &ref, &tl)) { 454 rc = ops->tree_connect(xid, tcon->ses, tcon->tree_name, 455 tcon, tcon->ses->local_nls); 456 goto out; 457 } 458 459 rc = tree_connect_dfs_target(xid, tcon, cifs_sb, tree, ref.server_type == DFS_TYPE_LINK, 460 &tl); 461 free_dfs_info_param(&ref); 462 463 out: 464 kfree(tree); 465 cifs_put_tcp_super(sb); 466 467 if (rc) { 468 spin_lock(&tcon->tc_lock); 469 if (tcon->status == TID_IN_TCON) 470 tcon->status = TID_NEED_TCON; 471 spin_unlock(&tcon->tc_lock); 472 } else { 473 spin_lock(&tcon->tc_lock); 474 if (tcon->status == TID_IN_TCON) 475 tcon->status = TID_GOOD; 476 tcon->need_reconnect = false; 477 spin_unlock(&tcon->tc_lock); 478 } 479 480 return rc; 481 } 482