fs/afs/cell.c

   1 /* AFS cell and server record management
   2  *
   3  * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/key.h>
  15 #include <linux/ctype.h>
  16 #include <linux/dns_resolver.h>
  17 #include <linux/sched.h>
  18 #include <keys/rxrpc-type.h>
  19 #include "internal.h"
  20
  21 DECLARE_RWSEM(afs_proc_cells_sem);
  22 LIST_HEAD(afs_proc_cells);
  23
  24 static LIST_HEAD(afs_cells);
  25 static DEFINE_RWLOCK(afs_cells_lock);
  26 static DECLARE_RWSEM(afs_cells_sem); /* add/remove serialisation */
  27 static DECLARE_WAIT_QUEUE_HEAD(afs_cells_freeable_wq);
  28 static struct afs_cell *afs_cell_root;
  29
  30 /*
  31  * allocate a cell record and fill in its name, VL server address list and
  32  * allocate an anonymous key
  33  */
  34 static struct afs_cell *afs_cell_alloc(const char *name, unsigned namelen,
  35                                        char *vllist)
  36 {
  37         struct afs_cell *cell;
  38         struct key *key;
  39         char keyname[4 + AFS_MAXCELLNAME + 1], *cp, *dp, *next;
  40         char  *dvllist = NULL, *_vllist = NULL;
  41         char  delimiter = ':';
  42         int ret;
  43
  44         _enter("%*.*s,%s", namelen, namelen, name ?: "", vllist);
  45
  46         BUG_ON(!name); /* TODO: want to look up "this cell" in the cache */
  47
  48         if (namelen > AFS_MAXCELLNAME) {
  49                 _leave(" = -ENAMETOOLONG");
  50                 return ERR_PTR(-ENAMETOOLONG);
  51         }
  52
  53         /* allocate and initialise a cell record */
  54         cell = kzalloc(sizeof(struct afs_cell) + namelen + 1, GFP_KERNEL);
  55         if (!cell) {
  56                 _leave(" = -ENOMEM");
  57                 return ERR_PTR(-ENOMEM);
  58         }
  59
  60         memcpy(cell->name, name, namelen);
  61         cell->name[namelen] = 0;
  62
  63         atomic_set(&cell->usage, 1);
  64         INIT_LIST_HEAD(&cell->link);
  65         rwlock_init(&cell->servers_lock);
  66         INIT_LIST_HEAD(&cell->servers);
  67         init_rwsem(&cell->vl_sem);
  68         INIT_LIST_HEAD(&cell->vl_list);
  69         spin_lock_init(&cell->vl_lock);
  70
  71         /* if the ip address is invalid, try dns query */
  72         if (!vllist || strlen(vllist) < 7) {
  73                 ret = dns_query("afsdb", name, namelen, "ipv4", &dvllist, NULL);
  74                 if (ret < 0) {
  75                         if (ret == -ENODATA || ret == -EAGAIN || ret == -ENOKEY)
  76                                 /* translate these errors into something
  77                                  * userspace might understand */
  78                                 ret = -EDESTADDRREQ;
  79                         _leave(" = %d", ret);
  80                         return ERR_PTR(ret);
  81                 }
  82                 _vllist = dvllist;
  83
  84                 /* change the delimiter for user-space reply */
  85                 delimiter = ',';
  86
  87         } else {
  88                 _vllist = vllist;
  89         }
  90
  91         /* fill in the VL server list from the rest of the string */
  92         do {
  93                 unsigned a, b, c, d;
  94
  95                 next = strchr(_vllist, delimiter);
  96                 if (next)
  97                         *next++ = 0;
  98
  99                 if (sscanf(_vllist, "%u.%u.%u.%u", &a, &b, &c, &d) != 4)
 100                         goto bad_address;
 101
 102                 if (a > 255 || b > 255 || c > 255 || d > 255)
 103                         goto bad_address;
 104
 105                 cell->vl_addrs[cell->vl_naddrs++].s_addr =
 106                         htonl((a << 24) | (b << 16) | (c << 8) | d);
 107
 108         } while (cell->vl_naddrs < AFS_CELL_MAX_ADDRS && (_vllist = next));
 109
 110         /* create a key to represent an anonymous user */
 111         memcpy(keyname, "afs@", 4);
 112         dp = keyname + 4;
 113         cp = cell->name;
 114         do {
 115                 *dp++ = toupper(*cp);
 116         } while (*cp++);
 117
 118         key = rxrpc_get_null_key(keyname);
 119         if (IS_ERR(key)) {
 120                 _debug("no key");
 121                 ret = PTR_ERR(key);
 122                 goto error;
 123         }
 124         cell->anonymous_key = key;
 125
 126         _debug("anon key %p{%x}",
 127                cell->anonymous_key, key_serial(cell->anonymous_key));
 128
 129         _leave(" = %p", cell);
 130         return cell;
 131
 132 bad_address:
 133         printk(KERN_ERR "kAFS: bad VL server IP address\n");
 134         ret = -EINVAL;
 135 error:
 136         key_put(cell->anonymous_key);
 137         kfree(dvllist);
 138         kfree(cell);
 139         _leave(" = %d", ret);
 140         return ERR_PTR(ret);
 141 }
 142
 143 /*
 144  * afs_cell_crate() - create a cell record
 145  * @name:       is the name of the cell.
 146  * @namsesz:    is the strlen of the cell name.
 147  * @vllist:     is a colon separated list of IP addresses in "a.b.c.d" format.
 148  * @retref:     is T to return the cell reference when the cell exists.
 149  */
 150 struct afs_cell *afs_cell_create(const char *name, unsigned namesz,
 151                                  char *vllist, bool retref)
 152 {
 153         struct afs_cell *cell;
 154         int ret;
 155
 156         _enter("%*.*s,%s", namesz, namesz, name ?: "", vllist);
 157
 158         down_write(&afs_cells_sem);
 159         read_lock(&afs_cells_lock);
 160         list_for_each_entry(cell, &afs_cells, link) {
 161                 if (strncasecmp(cell->name, name, namesz) == 0)
 162                         goto duplicate_name;
 163         }
 164         read_unlock(&afs_cells_lock);
 165
 166         cell = afs_cell_alloc(name, namesz, vllist);
 167         if (IS_ERR(cell)) {
 168                 _leave(" = %ld", PTR_ERR(cell));
 169                 up_write(&afs_cells_sem);
 170                 return cell;
 171         }
 172
 173         /* add a proc directory for this cell */
 174         ret = afs_proc_cell_setup(cell);
 175         if (ret < 0)
 176                 goto error;
 177
 178 #ifdef CONFIG_AFS_FSCACHE
 179         /* put it up for caching (this never returns an error) */
 180         cell->cache = fscache_acquire_cookie(afs_cache_netfs.primary_index,
 181                                              &afs_cell_cache_index_def,
 182                                              cell, true);
 183 #endif
 184
 185         /* add to the cell lists */
 186         write_lock(&afs_cells_lock);
 187         list_add_tail(&cell->link, &afs_cells);
 188         write_unlock(&afs_cells_lock);
 189
 190         down_write(&afs_proc_cells_sem);
 191         list_add_tail(&cell->proc_link, &afs_proc_cells);
 192         up_write(&afs_proc_cells_sem);
 193         up_write(&afs_cells_sem);
 194
 195         _leave(" = %p", cell);
 196         return cell;
 197
 198 error:
 199         up_write(&afs_cells_sem);
 200         key_put(cell->anonymous_key);
 201         kfree(cell);
 202         _leave(" = %d", ret);
 203         return ERR_PTR(ret);
 204
 205 duplicate_name:
 206         if (retref && !IS_ERR(cell))
 207                 afs_get_cell(cell);
 208
 209         read_unlock(&afs_cells_lock);
 210         up_write(&afs_cells_sem);
 211
 212         if (retref) {
 213                 _leave(" = %p", cell);
 214                 return cell;
 215         }
 216
 217         _leave(" = -EEXIST");
 218         return ERR_PTR(-EEXIST);
 219 }
 220
 221 /*
 222  * set the root cell information
 223  * - can be called with a module parameter string
 224  * - can be called from a write to /proc/fs/afs/rootcell
 225  */
 226 int afs_cell_init(char *rootcell)
 227 {
 228         struct afs_cell *old_root, *new_root;
 229         char *cp;
 230
 231         _enter("");
 232
 233         if (!rootcell) {
 234                 /* module is loaded with no parameters, or built statically.
 235                  * - in the future we might initialize cell DB here.
 236                  */
 237                 _leave(" = 0 [no root]");
 238                 return 0;
 239         }
 240
 241         cp = strchr(rootcell, ':');
 242         if (!cp)
 243                 _debug("kAFS: no VL server IP addresses specified");
 244         else
 245                 *cp++ = 0;
 246
 247         /* allocate a cell record for the root cell */
 248         new_root = afs_cell_create(rootcell, strlen(rootcell), cp, false);
 249         if (IS_ERR(new_root)) {
 250                 _leave(" = %ld", PTR_ERR(new_root));
 251                 return PTR_ERR(new_root);
 252         }
 253
 254         /* install the new cell */
 255         write_lock(&afs_cells_lock);
 256         old_root = afs_cell_root;
 257         afs_cell_root = new_root;
 258         write_unlock(&afs_cells_lock);
 259         afs_put_cell(old_root);
 260
 261         _leave(" = 0");
 262         return 0;
 263 }
 264
 265 /*
 266  * lookup a cell record
 267  */
 268 struct afs_cell *afs_cell_lookup(const char *name, unsigned namesz,
 269                                  bool dns_cell)
 270 {
 271         struct afs_cell *cell;
 272
 273         _enter("\"%*.*s\",", namesz, namesz, name ?: "");
 274
 275         down_read(&afs_cells_sem);
 276         read_lock(&afs_cells_lock);
 277
 278         if (name) {
 279                 /* if the cell was named, look for it in the cell record list */
 280                 list_for_each_entry(cell, &afs_cells, link) {
 281                         if (strncmp(cell->name, name, namesz) == 0) {
 282                                 afs_get_cell(cell);
 283                                 goto found;
 284                         }
 285                 }
 286                 cell = ERR_PTR(-ENOENT);
 287                 if (dns_cell)
 288                         goto create_cell;
 289         found:
 290                 ;
 291         } else {
 292                 cell = afs_cell_root;
 293                 if (!cell) {
 294                         /* this should not happen unless user tries to mount
 295                          * when root cell is not set. Return an impossibly
 296                          * bizarre errno to alert the user. Things like
 297                          * ENOENT might be "more appropriate" but they happen
 298                          * for other reasons.
 299                          */
 300                         cell = ERR_PTR(-EDESTADDRREQ);
 301                 } else {
 302                         afs_get_cell(cell);
 303                 }
 304
 305         }
 306
 307         read_unlock(&afs_cells_lock);
 308         up_read(&afs_cells_sem);
 309         _leave(" = %p", cell);
 310         return cell;
 311
 312 create_cell:
 313         read_unlock(&afs_cells_lock);
 314         up_read(&afs_cells_sem);
 315
 316         cell = afs_cell_create(name, namesz, NULL, true);
 317
 318         _leave(" = %p", cell);
 319         return cell;
 320 }
 321
 322 #if 0
 323 /*
 324  * try and get a cell record
 325  */
 326 struct afs_cell *afs_get_cell_maybe(struct afs_cell *cell)
 327 {
 328         write_lock(&afs_cells_lock);
 329
 330         if (cell && !list_empty(&cell->link))
 331                 afs_get_cell(cell);
 332         else
 333                 cell = NULL;
 334
 335         write_unlock(&afs_cells_lock);
 336         return cell;
 337 }
 338 #endif  /*  0  */
 339
 340 /*
 341  * destroy a cell record
 342  */
 343 void afs_put_cell(struct afs_cell *cell)
 344 {
 345         if (!cell)
 346                 return;
 347
 348         _enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);
 349
 350         ASSERTCMP(atomic_read(&cell->usage), >, 0);
 351
 352         /* to prevent a race, the decrement and the dequeue must be effectively
 353          * atomic */
 354         write_lock(&afs_cells_lock);
 355
 356         if (likely(!atomic_dec_and_test(&cell->usage))) {
 357                 write_unlock(&afs_cells_lock);
 358                 _leave("");
 359                 return;
 360         }
 361
 362         ASSERT(list_empty(&cell->servers));
 363         ASSERT(list_empty(&cell->vl_list));
 364
 365         write_unlock(&afs_cells_lock);
 366
 367         wake_up(&afs_cells_freeable_wq);
 368
 369         _leave(" [unused]");
 370 }
 371
 372 /*
 373  * destroy a cell record
 374  * - must be called with the afs_cells_sem write-locked
 375  * - cell->link should have been broken by the caller
 376  */
 377 static void afs_cell_destroy(struct afs_cell *cell)
 378 {
 379         _enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);
 380
 381         ASSERTCMP(atomic_read(&cell->usage), >=, 0);
 382         ASSERT(list_empty(&cell->link));
 383
 384         /* wait for everyone to stop using the cell */
 385         if (atomic_read(&cell->usage) > 0) {
 386                 DECLARE_WAITQUEUE(myself, current);
 387
 388                 _debug("wait for cell %s", cell->name);
 389                 set_current_state(TASK_UNINTERRUPTIBLE);
 390                 add_wait_queue(&afs_cells_freeable_wq, &myself);
 391
 392                 while (atomic_read(&cell->usage) > 0) {
 393                         schedule();
 394                         set_current_state(TASK_UNINTERRUPTIBLE);
 395                 }
 396
 397                 remove_wait_queue(&afs_cells_freeable_wq, &myself);
 398                 set_current_state(TASK_RUNNING);
 399         }
 400
 401         _debug("cell dead");
 402         ASSERTCMP(atomic_read(&cell->usage), ==, 0);
 403         ASSERT(list_empty(&cell->servers));
 404         ASSERT(list_empty(&cell->vl_list));
 405
 406         afs_proc_cell_remove(cell);
 407
 408         down_write(&afs_proc_cells_sem);
 409         list_del_init(&cell->proc_link);
 410         up_write(&afs_proc_cells_sem);
 411
 412 #ifdef CONFIG_AFS_FSCACHE
 413         fscache_relinquish_cookie(cell->cache, 0);
 414 #endif
 415         key_put(cell->anonymous_key);
 416         kfree(cell);
 417
 418         _leave(" [destroyed]");
 419 }
 420
 421 /*
 422  * purge in-memory cell database on module unload or afs_init() failure
 423  * - the timeout daemon is stopped before calling this
 424  */
 425 void afs_cell_purge(void)
 426 {
 427         struct afs_cell *cell;
 428
 429         _enter("");
 430
 431         afs_put_cell(afs_cell_root);
 432
 433         down_write(&afs_cells_sem);
 434
 435         while (!list_empty(&afs_cells)) {
 436                 cell = NULL;
 437
 438                 /* remove the next cell from the front of the list */
 439                 write_lock(&afs_cells_lock);
 440
 441                 if (!list_empty(&afs_cells)) {
 442                         cell = list_entry(afs_cells.next,
 443                                           struct afs_cell, link);
 444                         list_del_init(&cell->link);
 445                 }
 446
 447                 write_unlock(&afs_cells_lock);
 448
 449                 if (cell) {
 450                         _debug("PURGING CELL %s (%d)",
 451                                cell->name, atomic_read(&cell->usage));
 452
 453                         /* now the cell should be left with no references */
 454                         afs_cell_destroy(cell);
 455                 }
 456         }
 457
 458         up_write(&afs_cells_sem);
 459         _leave("");
 460 }