linux/fs/afs/cell.c
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   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
  21DECLARE_RWSEM(afs_proc_cells_sem);
  22LIST_HEAD(afs_proc_cells);
  23
  24static LIST_HEAD(afs_cells);
  25static DEFINE_RWLOCK(afs_cells_lock);
  26static DECLARE_RWSEM(afs_cells_sem); /* add/remove serialisation */
  27static DECLARE_WAIT_QUEUE_HEAD(afs_cells_freeable_wq);
  28static 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 */
  34static 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
 132bad_address:
 133        printk(KERN_ERR "kAFS: bad VL server IP address\n");
 134        ret = -EINVAL;
 135error:
 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 */
 150struct 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);
 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
 198error:
 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
 205duplicate_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 */
 226int 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 */
 268struct 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
 312create_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 */
 326struct 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 */
 343void 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 */
 377static 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 */
 425void 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}
 461
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