| 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
| 2 | /* AFS cell and server record management |
| 3 | * |
| 4 | * Copyright (C) 2002, 2017 Red Hat, Inc. All Rights Reserved. |
| 5 | * Written by David Howells (dhowells@redhat.com) |
| 6 | */ |
| 7 | |
| 8 | #include <linux/slab.h> |
| 9 | #include <linux/key.h> |
| 10 | #include <linux/ctype.h> |
| 11 | #include <linux/dns_resolver.h> |
| 12 | #include <linux/sched.h> |
| 13 | #include <linux/inet.h> |
| 14 | #include <linux/namei.h> |
| 15 | #include <keys/rxrpc-type.h> |
| 16 | #include "internal.h" |
| 17 | |
| 18 | static unsigned __read_mostly afs_cell_gc_delay = 10; |
| 19 | static unsigned __read_mostly afs_cell_min_ttl = 10 * 60; |
| 20 | static unsigned __read_mostly afs_cell_max_ttl = 24 * 60 * 60; |
| 21 | static atomic_t cell_debug_id; |
| 22 | |
| 23 | static void afs_queue_cell_manager(struct afs_net *); |
| 24 | static void afs_manage_cell_work(struct work_struct *); |
| 25 | |
| 26 | static void afs_dec_cells_outstanding(struct afs_net *net) |
| 27 | { |
| 28 | if (atomic_dec_and_test(&net->cells_outstanding)) |
| 29 | wake_up_var(&net->cells_outstanding); |
| 30 | } |
| 31 | |
| 32 | /* |
| 33 | * Set the cell timer to fire after a given delay, assuming it's not already |
| 34 | * set for an earlier time. |
| 35 | */ |
| 36 | static void afs_set_cell_timer(struct afs_net *net, time64_t delay) |
| 37 | { |
| 38 | if (net->live) { |
| 39 | atomic_inc(&net->cells_outstanding); |
| 40 | if (timer_reduce(&net->cells_timer, jiffies + delay * HZ)) |
| 41 | afs_dec_cells_outstanding(net); |
| 42 | } else { |
| 43 | afs_queue_cell_manager(net); |
| 44 | } |
| 45 | } |
| 46 | |
| 47 | /* |
| 48 | * Look up and get an activation reference on a cell record. The caller must |
| 49 | * hold net->cells_lock at least read-locked. |
| 50 | */ |
| 51 | static struct afs_cell *afs_find_cell_locked(struct afs_net *net, |
| 52 | const char *name, unsigned int namesz, |
| 53 | enum afs_cell_trace reason) |
| 54 | { |
| 55 | struct afs_cell *cell = NULL; |
| 56 | struct rb_node *p; |
| 57 | int n; |
| 58 | |
| 59 | _enter("%*.*s", namesz, namesz, name); |
| 60 | |
| 61 | if (name && namesz == 0) |
| 62 | return ERR_PTR(-EINVAL); |
| 63 | if (namesz > AFS_MAXCELLNAME) |
| 64 | return ERR_PTR(-ENAMETOOLONG); |
| 65 | |
| 66 | if (!name) { |
| 67 | cell = net->ws_cell; |
| 68 | if (!cell) |
| 69 | return ERR_PTR(-EDESTADDRREQ); |
| 70 | goto found; |
| 71 | } |
| 72 | |
| 73 | p = net->cells.rb_node; |
| 74 | while (p) { |
| 75 | cell = rb_entry(p, struct afs_cell, net_node); |
| 76 | |
| 77 | n = strncasecmp(cell->name, name, |
| 78 | min_t(size_t, cell->name_len, namesz)); |
| 79 | if (n == 0) |
| 80 | n = cell->name_len - namesz; |
| 81 | if (n < 0) |
| 82 | p = p->rb_left; |
| 83 | else if (n > 0) |
| 84 | p = p->rb_right; |
| 85 | else |
| 86 | goto found; |
| 87 | } |
| 88 | |
| 89 | return ERR_PTR(-ENOENT); |
| 90 | |
| 91 | found: |
| 92 | return afs_use_cell(cell, reason); |
| 93 | } |
| 94 | |
| 95 | /* |
| 96 | * Look up and get an activation reference on a cell record. |
| 97 | */ |
| 98 | struct afs_cell *afs_find_cell(struct afs_net *net, |
| 99 | const char *name, unsigned int namesz, |
| 100 | enum afs_cell_trace reason) |
| 101 | { |
| 102 | struct afs_cell *cell; |
| 103 | |
| 104 | down_read(&net->cells_lock); |
| 105 | cell = afs_find_cell_locked(net, name, namesz, reason); |
| 106 | up_read(&net->cells_lock); |
| 107 | return cell; |
| 108 | } |
| 109 | |
| 110 | /* |
| 111 | * Set up a cell record and fill in its name, VL server address list and |
| 112 | * allocate an anonymous key |
| 113 | */ |
| 114 | static struct afs_cell *afs_alloc_cell(struct afs_net *net, |
| 115 | const char *name, unsigned int namelen, |
| 116 | const char *addresses) |
| 117 | { |
| 118 | struct afs_vlserver_list *vllist; |
| 119 | struct afs_cell *cell; |
| 120 | int i, ret; |
| 121 | |
| 122 | ASSERT(name); |
| 123 | if (namelen == 0) |
| 124 | return ERR_PTR(-EINVAL); |
| 125 | if (namelen > AFS_MAXCELLNAME) { |
| 126 | _leave(" = -ENAMETOOLONG"); |
| 127 | return ERR_PTR(-ENAMETOOLONG); |
| 128 | } |
| 129 | |
| 130 | /* Prohibit cell names that contain unprintable chars, '/' and '@' or |
| 131 | * that begin with a dot. This also precludes "@cell". |
| 132 | */ |
| 133 | if (name[0] == '.') |
| 134 | return ERR_PTR(-EINVAL); |
| 135 | for (i = 0; i < namelen; i++) { |
| 136 | char ch = name[i]; |
| 137 | if (!isprint(ch) || ch == '/' || ch == '@') |
| 138 | return ERR_PTR(-EINVAL); |
| 139 | } |
| 140 | |
| 141 | _enter("%*.*s,%s", namelen, namelen, name, addresses); |
| 142 | |
| 143 | cell = kzalloc(sizeof(struct afs_cell), GFP_KERNEL); |
| 144 | if (!cell) { |
| 145 | _leave(" = -ENOMEM"); |
| 146 | return ERR_PTR(-ENOMEM); |
| 147 | } |
| 148 | |
| 149 | cell->name = kmalloc(namelen + 1, GFP_KERNEL); |
| 150 | if (!cell->name) { |
| 151 | kfree(cell); |
| 152 | return ERR_PTR(-ENOMEM); |
| 153 | } |
| 154 | |
| 155 | cell->net = net; |
| 156 | cell->name_len = namelen; |
| 157 | for (i = 0; i < namelen; i++) |
| 158 | cell->name[i] = tolower(name[i]); |
| 159 | cell->name[i] = 0; |
| 160 | |
| 161 | refcount_set(&cell->ref, 1); |
| 162 | atomic_set(&cell->active, 0); |
| 163 | INIT_WORK(&cell->manager, afs_manage_cell_work); |
| 164 | init_rwsem(&cell->vs_lock); |
| 165 | cell->volumes = RB_ROOT; |
| 166 | INIT_HLIST_HEAD(&cell->proc_volumes); |
| 167 | seqlock_init(&cell->volume_lock); |
| 168 | cell->fs_servers = RB_ROOT; |
| 169 | seqlock_init(&cell->fs_lock); |
| 170 | rwlock_init(&cell->vl_servers_lock); |
| 171 | cell->flags = (1 << AFS_CELL_FL_CHECK_ALIAS); |
| 172 | |
| 173 | /* Provide a VL server list, filling it in if we were given a list of |
| 174 | * addresses to use. |
| 175 | */ |
| 176 | if (addresses) { |
| 177 | vllist = afs_parse_text_addrs(net, |
| 178 | addresses, strlen(addresses), ':', |
| 179 | VL_SERVICE, AFS_VL_PORT); |
| 180 | if (IS_ERR(vllist)) { |
| 181 | ret = PTR_ERR(vllist); |
| 182 | goto parse_failed; |
| 183 | } |
| 184 | |
| 185 | vllist->source = DNS_RECORD_FROM_CONFIG; |
| 186 | vllist->status = DNS_LOOKUP_NOT_DONE; |
| 187 | cell->dns_expiry = TIME64_MAX; |
| 188 | } else { |
| 189 | ret = -ENOMEM; |
| 190 | vllist = afs_alloc_vlserver_list(0); |
| 191 | if (!vllist) |
| 192 | goto error; |
| 193 | vllist->source = DNS_RECORD_UNAVAILABLE; |
| 194 | vllist->status = DNS_LOOKUP_NOT_DONE; |
| 195 | cell->dns_expiry = ktime_get_real_seconds(); |
| 196 | } |
| 197 | |
| 198 | rcu_assign_pointer(cell->vl_servers, vllist); |
| 199 | |
| 200 | cell->dns_source = vllist->source; |
| 201 | cell->dns_status = vllist->status; |
| 202 | smp_store_release(&cell->dns_lookup_count, 1); /* vs source/status */ |
| 203 | atomic_inc(&net->cells_outstanding); |
| 204 | cell->debug_id = atomic_inc_return(&cell_debug_id); |
| 205 | trace_afs_cell(cell->debug_id, 1, 0, afs_cell_trace_alloc); |
| 206 | |
| 207 | _leave(" = %p", cell); |
| 208 | return cell; |
| 209 | |
| 210 | parse_failed: |
| 211 | if (ret == -EINVAL) |
| 212 | printk(KERN_ERR "kAFS: bad VL server IP address\n"); |
| 213 | error: |
| 214 | kfree(cell->name); |
| 215 | kfree(cell); |
| 216 | _leave(" = %d", ret); |
| 217 | return ERR_PTR(ret); |
| 218 | } |
| 219 | |
| 220 | /* |
| 221 | * afs_lookup_cell - Look up or create a cell record. |
| 222 | * @net: The network namespace |
| 223 | * @name: The name of the cell. |
| 224 | * @namesz: The strlen of the cell name. |
| 225 | * @vllist: A colon/comma separated list of numeric IP addresses or NULL. |
| 226 | * @excl: T if an error should be given if the cell name already exists. |
| 227 | * |
| 228 | * Look up a cell record by name and query the DNS for VL server addresses if |
| 229 | * needed. Note that that actual DNS query is punted off to the manager thread |
| 230 | * so that this function can return immediately if interrupted whilst allowing |
| 231 | * cell records to be shared even if not yet fully constructed. |
| 232 | */ |
| 233 | struct afs_cell *afs_lookup_cell(struct afs_net *net, |
| 234 | const char *name, unsigned int namesz, |
| 235 | const char *vllist, bool excl) |
| 236 | { |
| 237 | struct afs_cell *cell, *candidate, *cursor; |
| 238 | struct rb_node *parent, **pp; |
| 239 | enum afs_cell_state state; |
| 240 | int ret, n; |
| 241 | |
| 242 | _enter("%s,%s", name, vllist); |
| 243 | |
| 244 | if (!excl) { |
| 245 | cell = afs_find_cell(net, name, namesz, afs_cell_trace_use_lookup); |
| 246 | if (!IS_ERR(cell)) |
| 247 | goto wait_for_cell; |
| 248 | } |
| 249 | |
| 250 | /* Assume we're probably going to create a cell and preallocate and |
| 251 | * mostly set up a candidate record. We can then use this to stash the |
| 252 | * name, the net namespace and VL server addresses. |
| 253 | * |
| 254 | * We also want to do this before we hold any locks as it may involve |
| 255 | * upcalling to userspace to make DNS queries. |
| 256 | */ |
| 257 | candidate = afs_alloc_cell(net, name, namesz, vllist); |
| 258 | if (IS_ERR(candidate)) { |
| 259 | _leave(" = %ld", PTR_ERR(candidate)); |
| 260 | return candidate; |
| 261 | } |
| 262 | |
| 263 | /* Find the insertion point and check to see if someone else added a |
| 264 | * cell whilst we were allocating. |
| 265 | */ |
| 266 | down_write(&net->cells_lock); |
| 267 | |
| 268 | pp = &net->cells.rb_node; |
| 269 | parent = NULL; |
| 270 | while (*pp) { |
| 271 | parent = *pp; |
| 272 | cursor = rb_entry(parent, struct afs_cell, net_node); |
| 273 | |
| 274 | n = strncasecmp(cursor->name, name, |
| 275 | min_t(size_t, cursor->name_len, namesz)); |
| 276 | if (n == 0) |
| 277 | n = cursor->name_len - namesz; |
| 278 | if (n < 0) |
| 279 | pp = &(*pp)->rb_left; |
| 280 | else if (n > 0) |
| 281 | pp = &(*pp)->rb_right; |
| 282 | else |
| 283 | goto cell_already_exists; |
| 284 | } |
| 285 | |
| 286 | cell = candidate; |
| 287 | candidate = NULL; |
| 288 | atomic_set(&cell->active, 2); |
| 289 | trace_afs_cell(cell->debug_id, refcount_read(&cell->ref), 2, afs_cell_trace_insert); |
| 290 | rb_link_node_rcu(&cell->net_node, parent, pp); |
| 291 | rb_insert_color(&cell->net_node, &net->cells); |
| 292 | up_write(&net->cells_lock); |
| 293 | |
| 294 | afs_queue_cell(cell, afs_cell_trace_get_queue_new); |
| 295 | |
| 296 | wait_for_cell: |
| 297 | trace_afs_cell(cell->debug_id, refcount_read(&cell->ref), atomic_read(&cell->active), |
| 298 | afs_cell_trace_wait); |
| 299 | _debug("wait_for_cell"); |
| 300 | wait_var_event(&cell->state, |
| 301 | ({ |
| 302 | state = smp_load_acquire(&cell->state); /* vs error */ |
| 303 | state == AFS_CELL_ACTIVE || state == AFS_CELL_REMOVED; |
| 304 | })); |
| 305 | |
| 306 | /* Check the state obtained from the wait check. */ |
| 307 | if (state == AFS_CELL_REMOVED) { |
| 308 | ret = cell->error; |
| 309 | goto error; |
| 310 | } |
| 311 | |
| 312 | _leave(" = %p [cell]", cell); |
| 313 | return cell; |
| 314 | |
| 315 | cell_already_exists: |
| 316 | _debug("cell exists"); |
| 317 | cell = cursor; |
| 318 | if (excl) { |
| 319 | ret = -EEXIST; |
| 320 | } else { |
| 321 | afs_use_cell(cursor, afs_cell_trace_use_lookup); |
| 322 | ret = 0; |
| 323 | } |
| 324 | up_write(&net->cells_lock); |
| 325 | if (candidate) |
| 326 | afs_put_cell(candidate, afs_cell_trace_put_candidate); |
| 327 | if (ret == 0) |
| 328 | goto wait_for_cell; |
| 329 | goto error_noput; |
| 330 | error: |
| 331 | afs_unuse_cell(net, cell, afs_cell_trace_unuse_lookup); |
| 332 | error_noput: |
| 333 | _leave(" = %d [error]", ret); |
| 334 | return ERR_PTR(ret); |
| 335 | } |
| 336 | |
| 337 | /* |
| 338 | * set the root cell information |
| 339 | * - can be called with a module parameter string |
| 340 | * - can be called from a write to /proc/fs/afs/rootcell |
| 341 | */ |
| 342 | int afs_cell_init(struct afs_net *net, const char *rootcell) |
| 343 | { |
| 344 | struct afs_cell *old_root, *new_root; |
| 345 | const char *cp, *vllist; |
| 346 | size_t len; |
| 347 | |
| 348 | _enter(""); |
| 349 | |
| 350 | if (!rootcell) { |
| 351 | /* module is loaded with no parameters, or built statically. |
| 352 | * - in the future we might initialize cell DB here. |
| 353 | */ |
| 354 | _leave(" = 0 [no root]"); |
| 355 | return 0; |
| 356 | } |
| 357 | |
| 358 | cp = strchr(rootcell, ':'); |
| 359 | if (!cp) { |
| 360 | _debug("kAFS: no VL server IP addresses specified"); |
| 361 | vllist = NULL; |
| 362 | len = strlen(rootcell); |
| 363 | } else { |
| 364 | vllist = cp + 1; |
| 365 | len = cp - rootcell; |
| 366 | } |
| 367 | |
| 368 | /* allocate a cell record for the root cell */ |
| 369 | new_root = afs_lookup_cell(net, rootcell, len, vllist, false); |
| 370 | if (IS_ERR(new_root)) { |
| 371 | _leave(" = %ld", PTR_ERR(new_root)); |
| 372 | return PTR_ERR(new_root); |
| 373 | } |
| 374 | |
| 375 | if (!test_and_set_bit(AFS_CELL_FL_NO_GC, &new_root->flags)) |
| 376 | afs_use_cell(new_root, afs_cell_trace_use_pin); |
| 377 | |
| 378 | /* install the new cell */ |
| 379 | down_write(&net->cells_lock); |
| 380 | afs_see_cell(new_root, afs_cell_trace_see_ws); |
| 381 | old_root = net->ws_cell; |
| 382 | net->ws_cell = new_root; |
| 383 | up_write(&net->cells_lock); |
| 384 | |
| 385 | afs_unuse_cell(net, old_root, afs_cell_trace_unuse_ws); |
| 386 | _leave(" = 0"); |
| 387 | return 0; |
| 388 | } |
| 389 | |
| 390 | /* |
| 391 | * Update a cell's VL server address list from the DNS. |
| 392 | */ |
| 393 | static int afs_update_cell(struct afs_cell *cell) |
| 394 | { |
| 395 | struct afs_vlserver_list *vllist, *old = NULL, *p; |
| 396 | unsigned int min_ttl = READ_ONCE(afs_cell_min_ttl); |
| 397 | unsigned int max_ttl = READ_ONCE(afs_cell_max_ttl); |
| 398 | time64_t now, expiry = 0; |
| 399 | int ret = 0; |
| 400 | |
| 401 | _enter("%s", cell->name); |
| 402 | |
| 403 | vllist = afs_dns_query(cell, &expiry); |
| 404 | if (IS_ERR(vllist)) { |
| 405 | ret = PTR_ERR(vllist); |
| 406 | |
| 407 | _debug("%s: fail %d", cell->name, ret); |
| 408 | if (ret == -ENOMEM) |
| 409 | goto out_wake; |
| 410 | |
| 411 | vllist = afs_alloc_vlserver_list(0); |
| 412 | if (!vllist) { |
| 413 | if (ret >= 0) |
| 414 | ret = -ENOMEM; |
| 415 | goto out_wake; |
| 416 | } |
| 417 | |
| 418 | switch (ret) { |
| 419 | case -ENODATA: |
| 420 | case -EDESTADDRREQ: |
| 421 | vllist->status = DNS_LOOKUP_GOT_NOT_FOUND; |
| 422 | break; |
| 423 | case -EAGAIN: |
| 424 | case -ECONNREFUSED: |
| 425 | vllist->status = DNS_LOOKUP_GOT_TEMP_FAILURE; |
| 426 | break; |
| 427 | default: |
| 428 | vllist->status = DNS_LOOKUP_GOT_LOCAL_FAILURE; |
| 429 | break; |
| 430 | } |
| 431 | } |
| 432 | |
| 433 | _debug("%s: got list %d %d", cell->name, vllist->source, vllist->status); |
| 434 | cell->dns_status = vllist->status; |
| 435 | |
| 436 | now = ktime_get_real_seconds(); |
| 437 | if (min_ttl > max_ttl) |
| 438 | max_ttl = min_ttl; |
| 439 | if (expiry < now + min_ttl) |
| 440 | expiry = now + min_ttl; |
| 441 | else if (expiry > now + max_ttl) |
| 442 | expiry = now + max_ttl; |
| 443 | |
| 444 | _debug("%s: status %d", cell->name, vllist->status); |
| 445 | if (vllist->source == DNS_RECORD_UNAVAILABLE) { |
| 446 | switch (vllist->status) { |
| 447 | case DNS_LOOKUP_GOT_NOT_FOUND: |
| 448 | /* The DNS said that the cell does not exist or there |
| 449 | * weren't any addresses to be had. |
| 450 | */ |
| 451 | cell->dns_expiry = expiry; |
| 452 | break; |
| 453 | |
| 454 | case DNS_LOOKUP_BAD: |
| 455 | case DNS_LOOKUP_GOT_LOCAL_FAILURE: |
| 456 | case DNS_LOOKUP_GOT_TEMP_FAILURE: |
| 457 | case DNS_LOOKUP_GOT_NS_FAILURE: |
| 458 | default: |
| 459 | cell->dns_expiry = now + 10; |
| 460 | break; |
| 461 | } |
| 462 | } else { |
| 463 | cell->dns_expiry = expiry; |
| 464 | } |
| 465 | |
| 466 | /* Replace the VL server list if the new record has servers or the old |
| 467 | * record doesn't. |
| 468 | */ |
| 469 | write_lock(&cell->vl_servers_lock); |
| 470 | p = rcu_dereference_protected(cell->vl_servers, true); |
| 471 | if (vllist->nr_servers > 0 || p->nr_servers == 0) { |
| 472 | rcu_assign_pointer(cell->vl_servers, vllist); |
| 473 | cell->dns_source = vllist->source; |
| 474 | old = p; |
| 475 | } |
| 476 | write_unlock(&cell->vl_servers_lock); |
| 477 | afs_put_vlserverlist(cell->net, old); |
| 478 | |
| 479 | out_wake: |
| 480 | smp_store_release(&cell->dns_lookup_count, |
| 481 | cell->dns_lookup_count + 1); /* vs source/status */ |
| 482 | wake_up_var(&cell->dns_lookup_count); |
| 483 | _leave(" = %d", ret); |
| 484 | return ret; |
| 485 | } |
| 486 | |
| 487 | /* |
| 488 | * Destroy a cell record |
| 489 | */ |
| 490 | static void afs_cell_destroy(struct rcu_head *rcu) |
| 491 | { |
| 492 | struct afs_cell *cell = container_of(rcu, struct afs_cell, rcu); |
| 493 | struct afs_net *net = cell->net; |
| 494 | int r; |
| 495 | |
| 496 | _enter("%p{%s}", cell, cell->name); |
| 497 | |
| 498 | r = refcount_read(&cell->ref); |
| 499 | ASSERTCMP(r, ==, 0); |
| 500 | trace_afs_cell(cell->debug_id, r, atomic_read(&cell->active), afs_cell_trace_free); |
| 501 | |
| 502 | afs_put_vlserverlist(net, rcu_access_pointer(cell->vl_servers)); |
| 503 | afs_unuse_cell(net, cell->alias_of, afs_cell_trace_unuse_alias); |
| 504 | key_put(cell->anonymous_key); |
| 505 | kfree(cell->name); |
| 506 | kfree(cell); |
| 507 | |
| 508 | afs_dec_cells_outstanding(net); |
| 509 | _leave(" [destroyed]"); |
| 510 | } |
| 511 | |
| 512 | /* |
| 513 | * Queue the cell manager. |
| 514 | */ |
| 515 | static void afs_queue_cell_manager(struct afs_net *net) |
| 516 | { |
| 517 | int outstanding = atomic_inc_return(&net->cells_outstanding); |
| 518 | |
| 519 | _enter("%d", outstanding); |
| 520 | |
| 521 | if (!queue_work(afs_wq, &net->cells_manager)) |
| 522 | afs_dec_cells_outstanding(net); |
| 523 | } |
| 524 | |
| 525 | /* |
| 526 | * Cell management timer. We have an increment on cells_outstanding that we |
| 527 | * need to pass along to the work item. |
| 528 | */ |
| 529 | void afs_cells_timer(struct timer_list *timer) |
| 530 | { |
| 531 | struct afs_net *net = container_of(timer, struct afs_net, cells_timer); |
| 532 | |
| 533 | _enter(""); |
| 534 | if (!queue_work(afs_wq, &net->cells_manager)) |
| 535 | afs_dec_cells_outstanding(net); |
| 536 | } |
| 537 | |
| 538 | /* |
| 539 | * Get a reference on a cell record. |
| 540 | */ |
| 541 | struct afs_cell *afs_get_cell(struct afs_cell *cell, enum afs_cell_trace reason) |
| 542 | { |
| 543 | int r; |
| 544 | |
| 545 | __refcount_inc(&cell->ref, &r); |
| 546 | trace_afs_cell(cell->debug_id, r + 1, atomic_read(&cell->active), reason); |
| 547 | return cell; |
| 548 | } |
| 549 | |
| 550 | /* |
| 551 | * Drop a reference on a cell record. |
| 552 | */ |
| 553 | void afs_put_cell(struct afs_cell *cell, enum afs_cell_trace reason) |
| 554 | { |
| 555 | if (cell) { |
| 556 | unsigned int debug_id = cell->debug_id; |
| 557 | unsigned int a; |
| 558 | bool zero; |
| 559 | int r; |
| 560 | |
| 561 | a = atomic_read(&cell->active); |
| 562 | zero = __refcount_dec_and_test(&cell->ref, &r); |
| 563 | trace_afs_cell(debug_id, r - 1, a, reason); |
| 564 | if (zero) { |
| 565 | a = atomic_read(&cell->active); |
| 566 | WARN(a != 0, "Cell active count %u > 0\n", a); |
| 567 | call_rcu(&cell->rcu, afs_cell_destroy); |
| 568 | } |
| 569 | } |
| 570 | } |
| 571 | |
| 572 | /* |
| 573 | * Note a cell becoming more active. |
| 574 | */ |
| 575 | struct afs_cell *afs_use_cell(struct afs_cell *cell, enum afs_cell_trace reason) |
| 576 | { |
| 577 | int r, a; |
| 578 | |
| 579 | r = refcount_read(&cell->ref); |
| 580 | WARN_ON(r == 0); |
| 581 | a = atomic_inc_return(&cell->active); |
| 582 | trace_afs_cell(cell->debug_id, r, a, reason); |
| 583 | return cell; |
| 584 | } |
| 585 | |
| 586 | /* |
| 587 | * Record a cell becoming less active. When the active counter reaches 1, it |
| 588 | * is scheduled for destruction, but may get reactivated. |
| 589 | */ |
| 590 | void afs_unuse_cell(struct afs_net *net, struct afs_cell *cell, enum afs_cell_trace reason) |
| 591 | { |
| 592 | unsigned int debug_id; |
| 593 | time64_t now, expire_delay; |
| 594 | int r, a; |
| 595 | |
| 596 | if (!cell) |
| 597 | return; |
| 598 | |
| 599 | _enter("%s", cell->name); |
| 600 | |
| 601 | now = ktime_get_real_seconds(); |
| 602 | cell->last_inactive = now; |
| 603 | expire_delay = 0; |
| 604 | if (cell->vl_servers->nr_servers) |
| 605 | expire_delay = afs_cell_gc_delay; |
| 606 | |
| 607 | debug_id = cell->debug_id; |
| 608 | r = refcount_read(&cell->ref); |
| 609 | a = atomic_dec_return(&cell->active); |
| 610 | trace_afs_cell(debug_id, r, a, reason); |
| 611 | WARN_ON(a == 0); |
| 612 | if (a == 1) |
| 613 | /* 'cell' may now be garbage collected. */ |
| 614 | afs_set_cell_timer(net, expire_delay); |
| 615 | } |
| 616 | |
| 617 | /* |
| 618 | * Note that a cell has been seen. |
| 619 | */ |
| 620 | void afs_see_cell(struct afs_cell *cell, enum afs_cell_trace reason) |
| 621 | { |
| 622 | int r, a; |
| 623 | |
| 624 | r = refcount_read(&cell->ref); |
| 625 | a = atomic_read(&cell->active); |
| 626 | trace_afs_cell(cell->debug_id, r, a, reason); |
| 627 | } |
| 628 | |
| 629 | /* |
| 630 | * Queue a cell for management, giving the workqueue a ref to hold. |
| 631 | */ |
| 632 | void afs_queue_cell(struct afs_cell *cell, enum afs_cell_trace reason) |
| 633 | { |
| 634 | afs_get_cell(cell, reason); |
| 635 | if (!queue_work(afs_wq, &cell->manager)) |
| 636 | afs_put_cell(cell, afs_cell_trace_put_queue_fail); |
| 637 | } |
| 638 | |
| 639 | /* |
| 640 | * Allocate a key to use as a placeholder for anonymous user security. |
| 641 | */ |
| 642 | static int afs_alloc_anon_key(struct afs_cell *cell) |
| 643 | { |
| 644 | struct key *key; |
| 645 | char keyname[4 + AFS_MAXCELLNAME + 1], *cp, *dp; |
| 646 | |
| 647 | /* Create a key to represent an anonymous user. */ |
| 648 | memcpy(keyname, "afs@", 4); |
| 649 | dp = keyname + 4; |
| 650 | cp = cell->name; |
| 651 | do { |
| 652 | *dp++ = tolower(*cp); |
| 653 | } while (*cp++); |
| 654 | |
| 655 | key = rxrpc_get_null_key(keyname); |
| 656 | if (IS_ERR(key)) |
| 657 | return PTR_ERR(key); |
| 658 | |
| 659 | cell->anonymous_key = key; |
| 660 | |
| 661 | _debug("anon key %p{%x}", |
| 662 | cell->anonymous_key, key_serial(cell->anonymous_key)); |
| 663 | return 0; |
| 664 | } |
| 665 | |
| 666 | /* |
| 667 | * Activate a cell. |
| 668 | */ |
| 669 | static int afs_activate_cell(struct afs_net *net, struct afs_cell *cell) |
| 670 | { |
| 671 | struct hlist_node **p; |
| 672 | struct afs_cell *pcell; |
| 673 | int ret; |
| 674 | |
| 675 | if (!cell->anonymous_key) { |
| 676 | ret = afs_alloc_anon_key(cell); |
| 677 | if (ret < 0) |
| 678 | return ret; |
| 679 | } |
| 680 | |
| 681 | ret = afs_proc_cell_setup(cell); |
| 682 | if (ret < 0) |
| 683 | return ret; |
| 684 | |
| 685 | mutex_lock(&net->proc_cells_lock); |
| 686 | for (p = &net->proc_cells.first; *p; p = &(*p)->next) { |
| 687 | pcell = hlist_entry(*p, struct afs_cell, proc_link); |
| 688 | if (strcmp(cell->name, pcell->name) < 0) |
| 689 | break; |
| 690 | } |
| 691 | |
| 692 | cell->proc_link.pprev = p; |
| 693 | cell->proc_link.next = *p; |
| 694 | rcu_assign_pointer(*p, &cell->proc_link.next); |
| 695 | if (cell->proc_link.next) |
| 696 | cell->proc_link.next->pprev = &cell->proc_link.next; |
| 697 | |
| 698 | afs_dynroot_mkdir(net, cell); |
| 699 | mutex_unlock(&net->proc_cells_lock); |
| 700 | return 0; |
| 701 | } |
| 702 | |
| 703 | /* |
| 704 | * Deactivate a cell. |
| 705 | */ |
| 706 | static void afs_deactivate_cell(struct afs_net *net, struct afs_cell *cell) |
| 707 | { |
| 708 | _enter("%s", cell->name); |
| 709 | |
| 710 | afs_proc_cell_remove(cell); |
| 711 | |
| 712 | mutex_lock(&net->proc_cells_lock); |
| 713 | hlist_del_rcu(&cell->proc_link); |
| 714 | afs_dynroot_rmdir(net, cell); |
| 715 | mutex_unlock(&net->proc_cells_lock); |
| 716 | |
| 717 | _leave(""); |
| 718 | } |
| 719 | |
| 720 | /* |
| 721 | * Manage a cell record, initialising and destroying it, maintaining its DNS |
| 722 | * records. |
| 723 | */ |
| 724 | static void afs_manage_cell(struct afs_cell *cell) |
| 725 | { |
| 726 | struct afs_net *net = cell->net; |
| 727 | int ret, active; |
| 728 | |
| 729 | _enter("%s", cell->name); |
| 730 | |
| 731 | again: |
| 732 | _debug("state %u", cell->state); |
| 733 | switch (cell->state) { |
| 734 | case AFS_CELL_INACTIVE: |
| 735 | case AFS_CELL_FAILED: |
| 736 | down_write(&net->cells_lock); |
| 737 | active = 1; |
| 738 | if (atomic_try_cmpxchg_relaxed(&cell->active, &active, 0)) { |
| 739 | rb_erase(&cell->net_node, &net->cells); |
| 740 | trace_afs_cell(cell->debug_id, refcount_read(&cell->ref), 0, |
| 741 | afs_cell_trace_unuse_delete); |
| 742 | smp_store_release(&cell->state, AFS_CELL_REMOVED); |
| 743 | } |
| 744 | up_write(&net->cells_lock); |
| 745 | if (cell->state == AFS_CELL_REMOVED) { |
| 746 | wake_up_var(&cell->state); |
| 747 | goto final_destruction; |
| 748 | } |
| 749 | if (cell->state == AFS_CELL_FAILED) |
| 750 | goto done; |
| 751 | smp_store_release(&cell->state, AFS_CELL_UNSET); |
| 752 | wake_up_var(&cell->state); |
| 753 | goto again; |
| 754 | |
| 755 | case AFS_CELL_UNSET: |
| 756 | smp_store_release(&cell->state, AFS_CELL_ACTIVATING); |
| 757 | wake_up_var(&cell->state); |
| 758 | goto again; |
| 759 | |
| 760 | case AFS_CELL_ACTIVATING: |
| 761 | ret = afs_activate_cell(net, cell); |
| 762 | if (ret < 0) |
| 763 | goto activation_failed; |
| 764 | |
| 765 | smp_store_release(&cell->state, AFS_CELL_ACTIVE); |
| 766 | wake_up_var(&cell->state); |
| 767 | goto again; |
| 768 | |
| 769 | case AFS_CELL_ACTIVE: |
| 770 | if (atomic_read(&cell->active) > 1) { |
| 771 | if (test_and_clear_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags)) { |
| 772 | ret = afs_update_cell(cell); |
| 773 | if (ret < 0) |
| 774 | cell->error = ret; |
| 775 | } |
| 776 | goto done; |
| 777 | } |
| 778 | smp_store_release(&cell->state, AFS_CELL_DEACTIVATING); |
| 779 | wake_up_var(&cell->state); |
| 780 | goto again; |
| 781 | |
| 782 | case AFS_CELL_DEACTIVATING: |
| 783 | if (atomic_read(&cell->active) > 1) |
| 784 | goto reverse_deactivation; |
| 785 | afs_deactivate_cell(net, cell); |
| 786 | smp_store_release(&cell->state, AFS_CELL_INACTIVE); |
| 787 | wake_up_var(&cell->state); |
| 788 | goto again; |
| 789 | |
| 790 | case AFS_CELL_REMOVED: |
| 791 | goto done; |
| 792 | |
| 793 | default: |
| 794 | break; |
| 795 | } |
| 796 | _debug("bad state %u", cell->state); |
| 797 | BUG(); /* Unhandled state */ |
| 798 | |
| 799 | activation_failed: |
| 800 | cell->error = ret; |
| 801 | afs_deactivate_cell(net, cell); |
| 802 | |
| 803 | smp_store_release(&cell->state, AFS_CELL_FAILED); /* vs error */ |
| 804 | wake_up_var(&cell->state); |
| 805 | goto again; |
| 806 | |
| 807 | reverse_deactivation: |
| 808 | smp_store_release(&cell->state, AFS_CELL_ACTIVE); |
| 809 | wake_up_var(&cell->state); |
| 810 | _leave(" [deact->act]"); |
| 811 | return; |
| 812 | |
| 813 | done: |
| 814 | _leave(" [done %u]", cell->state); |
| 815 | return; |
| 816 | |
| 817 | final_destruction: |
| 818 | /* The root volume is pinning the cell */ |
| 819 | afs_put_volume(cell->root_volume, afs_volume_trace_put_cell_root); |
| 820 | cell->root_volume = NULL; |
| 821 | afs_put_cell(cell, afs_cell_trace_put_destroy); |
| 822 | } |
| 823 | |
| 824 | static void afs_manage_cell_work(struct work_struct *work) |
| 825 | { |
| 826 | struct afs_cell *cell = container_of(work, struct afs_cell, manager); |
| 827 | |
| 828 | afs_manage_cell(cell); |
| 829 | afs_put_cell(cell, afs_cell_trace_put_queue_work); |
| 830 | } |
| 831 | |
| 832 | /* |
| 833 | * Manage the records of cells known to a network namespace. This includes |
| 834 | * updating the DNS records and garbage collecting unused cells that were |
| 835 | * automatically added. |
| 836 | * |
| 837 | * Note that constructed cell records may only be removed from net->cells by |
| 838 | * this work item, so it is safe for this work item to stash a cursor pointing |
| 839 | * into the tree and then return to caller (provided it skips cells that are |
| 840 | * still under construction). |
| 841 | * |
| 842 | * Note also that we were given an increment on net->cells_outstanding by |
| 843 | * whoever queued us that we need to deal with before returning. |
| 844 | */ |
| 845 | void afs_manage_cells(struct work_struct *work) |
| 846 | { |
| 847 | struct afs_net *net = container_of(work, struct afs_net, cells_manager); |
| 848 | struct rb_node *cursor; |
| 849 | time64_t now = ktime_get_real_seconds(), next_manage = TIME64_MAX; |
| 850 | bool purging = !net->live; |
| 851 | |
| 852 | _enter(""); |
| 853 | |
| 854 | /* Trawl the cell database looking for cells that have expired from |
| 855 | * lack of use and cells whose DNS results have expired and dispatch |
| 856 | * their managers. |
| 857 | */ |
| 858 | down_read(&net->cells_lock); |
| 859 | |
| 860 | for (cursor = rb_first(&net->cells); cursor; cursor = rb_next(cursor)) { |
| 861 | struct afs_cell *cell = |
| 862 | rb_entry(cursor, struct afs_cell, net_node); |
| 863 | unsigned active; |
| 864 | bool sched_cell = false; |
| 865 | |
| 866 | active = atomic_read(&cell->active); |
| 867 | trace_afs_cell(cell->debug_id, refcount_read(&cell->ref), |
| 868 | active, afs_cell_trace_manage); |
| 869 | |
| 870 | ASSERTCMP(active, >=, 1); |
| 871 | |
| 872 | if (purging) { |
| 873 | if (test_and_clear_bit(AFS_CELL_FL_NO_GC, &cell->flags)) { |
| 874 | active = atomic_dec_return(&cell->active); |
| 875 | trace_afs_cell(cell->debug_id, refcount_read(&cell->ref), |
| 876 | active, afs_cell_trace_unuse_pin); |
| 877 | } |
| 878 | } |
| 879 | |
| 880 | if (active == 1) { |
| 881 | struct afs_vlserver_list *vllist; |
| 882 | time64_t expire_at = cell->last_inactive; |
| 883 | |
| 884 | read_lock(&cell->vl_servers_lock); |
| 885 | vllist = rcu_dereference_protected( |
| 886 | cell->vl_servers, |
| 887 | lockdep_is_held(&cell->vl_servers_lock)); |
| 888 | if (vllist->nr_servers > 0) |
| 889 | expire_at += afs_cell_gc_delay; |
| 890 | read_unlock(&cell->vl_servers_lock); |
| 891 | if (purging || expire_at <= now) |
| 892 | sched_cell = true; |
| 893 | else if (expire_at < next_manage) |
| 894 | next_manage = expire_at; |
| 895 | } |
| 896 | |
| 897 | if (!purging) { |
| 898 | if (test_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags)) |
| 899 | sched_cell = true; |
| 900 | } |
| 901 | |
| 902 | if (sched_cell) |
| 903 | afs_queue_cell(cell, afs_cell_trace_get_queue_manage); |
| 904 | } |
| 905 | |
| 906 | up_read(&net->cells_lock); |
| 907 | |
| 908 | /* Update the timer on the way out. We have to pass an increment on |
| 909 | * cells_outstanding in the namespace that we are in to the timer or |
| 910 | * the work scheduler. |
| 911 | */ |
| 912 | if (!purging && next_manage < TIME64_MAX) { |
| 913 | now = ktime_get_real_seconds(); |
| 914 | |
| 915 | if (next_manage - now <= 0) { |
| 916 | if (queue_work(afs_wq, &net->cells_manager)) |
| 917 | atomic_inc(&net->cells_outstanding); |
| 918 | } else { |
| 919 | afs_set_cell_timer(net, next_manage - now); |
| 920 | } |
| 921 | } |
| 922 | |
| 923 | afs_dec_cells_outstanding(net); |
| 924 | _leave(" [%d]", atomic_read(&net->cells_outstanding)); |
| 925 | } |
| 926 | |
| 927 | /* |
| 928 | * Purge in-memory cell database. |
| 929 | */ |
| 930 | void afs_cell_purge(struct afs_net *net) |
| 931 | { |
| 932 | struct afs_cell *ws; |
| 933 | |
| 934 | _enter(""); |
| 935 | |
| 936 | down_write(&net->cells_lock); |
| 937 | ws = net->ws_cell; |
| 938 | net->ws_cell = NULL; |
| 939 | up_write(&net->cells_lock); |
| 940 | afs_unuse_cell(net, ws, afs_cell_trace_unuse_ws); |
| 941 | |
| 942 | _debug("del timer"); |
| 943 | if (del_timer_sync(&net->cells_timer)) |
| 944 | atomic_dec(&net->cells_outstanding); |
| 945 | |
| 946 | _debug("kick mgr"); |
| 947 | afs_queue_cell_manager(net); |
| 948 | |
| 949 | _debug("wait"); |
| 950 | wait_var_event(&net->cells_outstanding, |
| 951 | !atomic_read(&net->cells_outstanding)); |
| 952 | _leave(""); |
| 953 | } |