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