fs/quota/quota.c

   1 /*
   2  * Quota code necessary even when VFS quota support is not compiled
   3  * into the kernel.  The interesting stuff is over in dquot.c, here
   4  * we have symbols for initial quotactl(2) handling, the sysctl(2)
   5  * variables, etc - things needed even when quota support disabled.
   6  */
   7
   8 #include <linux/fs.h>
   9 #include <linux/namei.h>
  10 #include <linux/slab.h>
  11 #include <asm/current.h>
  12 #include <asm/uaccess.h>
  13 #include <linux/compat.h>
  14 #include <linux/kernel.h>
  15 #include <linux/security.h>
  16 #include <linux/syscalls.h>
  17 #include <linux/buffer_head.h>
  18 #include <linux/capability.h>
  19 #include <linux/quotaops.h>
  20 #include <linux/types.h>
  21 #include <net/netlink.h>
  22 #include <net/genetlink.h>
  23
  24 /* Check validity of generic quotactl commands */
  25 static int generic_quotactl_valid(struct super_block *sb, int type, int cmd,
  26                                   qid_t id)
  27 {
  28         if (type >= MAXQUOTAS)
  29                 return -EINVAL;
  30         if (!sb && cmd != Q_SYNC)
  31                 return -ENODEV;
  32         /* Is operation supported? */
  33         if (sb && !sb->s_qcop)
  34                 return -ENOSYS;
  35
  36         switch (cmd) {
  37                 case Q_GETFMT:
  38                         break;
  39                 case Q_QUOTAON:
  40                         if (!sb->s_qcop->quota_on)
  41                                 return -ENOSYS;
  42                         break;
  43                 case Q_QUOTAOFF:
  44                         if (!sb->s_qcop->quota_off)
  45                                 return -ENOSYS;
  46                         break;
  47                 case Q_SETINFO:
  48                         if (!sb->s_qcop->set_info)
  49                                 return -ENOSYS;
  50                         break;
  51                 case Q_GETINFO:
  52                         if (!sb->s_qcop->get_info)
  53                                 return -ENOSYS;
  54                         break;
  55                 case Q_SETQUOTA:
  56                         if (!sb->s_qcop->set_dqblk)
  57                                 return -ENOSYS;
  58                         break;
  59                 case Q_GETQUOTA:
  60                         if (!sb->s_qcop->get_dqblk)
  61                                 return -ENOSYS;
  62                         break;
  63                 case Q_SYNC:
  64                         if (sb && !sb->s_qcop->quota_sync)
  65                                 return -ENOSYS;
  66                         break;
  67                 default:
  68                         return -EINVAL;
  69         }
  70
  71         /* Is quota turned on for commands which need it? */
  72         switch (cmd) {
  73                 case Q_GETFMT:
  74                 case Q_GETINFO:
  75                 case Q_SETINFO:
  76                 case Q_SETQUOTA:
  77                 case Q_GETQUOTA:
  78                         /* This is just an informative test so we are satisfied
  79                          * without the lock */
  80                         if (!sb_has_quota_active(sb, type))
  81                                 return -ESRCH;
  82         }
  83
  84         /* Check privileges */
  85         if (cmd == Q_GETQUOTA) {
  86                 if (((type == USRQUOTA && current_euid() != id) ||
  87                      (type == GRPQUOTA && !in_egroup_p(id))) &&
  88                     !capable(CAP_SYS_ADMIN))
  89                         return -EPERM;
  90         }
  91         else if (cmd != Q_GETFMT && cmd != Q_SYNC && cmd != Q_GETINFO)
  92                 if (!capable(CAP_SYS_ADMIN))
  93                         return -EPERM;
  94
  95         return 0;
  96 }
  97
  98 /* Check validity of XFS Quota Manager commands */
  99 static int xqm_quotactl_valid(struct super_block *sb, int type, int cmd,
 100                               qid_t id)
 101 {
 102         if (type >= XQM_MAXQUOTAS)
 103                 return -EINVAL;
 104         if (!sb)
 105                 return -ENODEV;
 106         if (!sb->s_qcop)
 107                 return -ENOSYS;
 108
 109         switch (cmd) {
 110                 case Q_XQUOTAON:
 111                 case Q_XQUOTAOFF:
 112                 case Q_XQUOTARM:
 113                         if (!sb->s_qcop->set_xstate)
 114                                 return -ENOSYS;
 115                         break;
 116                 case Q_XGETQSTAT:
 117                         if (!sb->s_qcop->get_xstate)
 118                                 return -ENOSYS;
 119                         break;
 120                 case Q_XSETQLIM:
 121                         if (!sb->s_qcop->set_xquota)
 122                                 return -ENOSYS;
 123                         break;
 124                 case Q_XGETQUOTA:
 125                         if (!sb->s_qcop->get_xquota)
 126                                 return -ENOSYS;
 127                         break;
 128                 case Q_XQUOTASYNC:
 129                         if (!sb->s_qcop->quota_sync)
 130                                 return -ENOSYS;
 131                         break;
 132                 default:
 133                         return -EINVAL;
 134         }
 135
 136         /* Check privileges */
 137         if (cmd == Q_XGETQUOTA) {
 138                 if (((type == XQM_USRQUOTA && current_euid() != id) ||
 139                      (type == XQM_GRPQUOTA && !in_egroup_p(id))) &&
 140                      !capable(CAP_SYS_ADMIN))
 141                         return -EPERM;
 142         } else if (cmd != Q_XGETQSTAT && cmd != Q_XQUOTASYNC) {
 143                 if (!capable(CAP_SYS_ADMIN))
 144                         return -EPERM;
 145         }
 146
 147         return 0;
 148 }
 149
 150 static int check_quotactl_valid(struct super_block *sb, int type, int cmd,
 151                                 qid_t id)
 152 {
 153         int error;
 154
 155         if (XQM_COMMAND(cmd))
 156                 error = xqm_quotactl_valid(sb, type, cmd, id);
 157         else
 158                 error = generic_quotactl_valid(sb, type, cmd, id);
 159         if (!error)
 160                 error = security_quotactl(cmd, type, id, sb);
 161         return error;
 162 }
 163
 164 #ifdef CONFIG_QUOTA
 165 void sync_quota_sb(struct super_block *sb, int type)
 166 {
 167         int cnt;
 168
 169         if (!sb->s_qcop->quota_sync)
 170                 return;
 171
 172         sb->s_qcop->quota_sync(sb, type);
 173
 174         if (sb_dqopt(sb)->flags & DQUOT_QUOTA_SYS_FILE)
 175                 return;
 176         /* This is not very clever (and fast) but currently I don't know about
 177          * any other simple way of getting quota data to disk and we must get
 178          * them there for userspace to be visible... */
 179         if (sb->s_op->sync_fs)
 180                 sb->s_op->sync_fs(sb, 1);
 181         sync_blockdev(sb->s_bdev);
 182
 183         /*
 184          * Now when everything is written we can discard the pagecache so
 185          * that userspace sees the changes.
 186          */
 187         mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
 188         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 189                 if (type != -1 && cnt != type)
 190                         continue;
 191                 if (!sb_has_quota_active(sb, cnt))
 192                         continue;
 193                 mutex_lock_nested(&sb_dqopt(sb)->files[cnt]->i_mutex,
 194                                   I_MUTEX_QUOTA);
 195                 truncate_inode_pages(&sb_dqopt(sb)->files[cnt]->i_data, 0);
 196                 mutex_unlock(&sb_dqopt(sb)->files[cnt]->i_mutex);
 197         }
 198         mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
 199 }
 200 #endif
 201
 202 static void sync_dquots(int type)
 203 {
 204         struct super_block *sb;
 205         int cnt;
 206
 207         spin_lock(&sb_lock);
 208 restart:
 209         list_for_each_entry(sb, &super_blocks, s_list) {
 210                 /* This test just improves performance so it needn't be
 211                  * reliable... */
 212                 for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 213                         if (type != -1 && type != cnt)
 214                                 continue;
 215                         if (!sb_has_quota_active(sb, cnt))
 216                                 continue;
 217                         if (!info_dirty(&sb_dqopt(sb)->info[cnt]) &&
 218                            list_empty(&sb_dqopt(sb)->info[cnt].dqi_dirty_list))
 219                                 continue;
 220                         break;
 221                 }
 222                 if (cnt == MAXQUOTAS)
 223                         continue;
 224                 sb->s_count++;
 225                 spin_unlock(&sb_lock);
 226                 down_read(&sb->s_umount);
 227                 if (sb->s_root)
 228                         sync_quota_sb(sb, type);
 229                 up_read(&sb->s_umount);
 230                 spin_lock(&sb_lock);
 231                 if (__put_super_and_need_restart(sb))
 232                         goto restart;
 233         }
 234         spin_unlock(&sb_lock);
 235 }
 236
 237 /* Copy parameters and call proper function */
 238 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
 239                        void __user *addr)
 240 {
 241         int ret;
 242
 243         switch (cmd) {
 244                 case Q_QUOTAON: {
 245                         char *pathname;
 246
 247                         pathname = getname(addr);
 248                         if (IS_ERR(pathname))
 249                                 return PTR_ERR(pathname);
 250                         ret = sb->s_qcop->quota_on(sb, type, id, pathname, 0);
 251                         putname(pathname);
 252                         return ret;
 253                 }
 254                 case Q_QUOTAOFF:
 255                         return sb->s_qcop->quota_off(sb, type, 0);
 256
 257                 case Q_GETFMT: {
 258                         __u32 fmt;
 259
 260                         down_read(&sb_dqopt(sb)->dqptr_sem);
 261                         if (!sb_has_quota_active(sb, type)) {
 262                                 up_read(&sb_dqopt(sb)->dqptr_sem);
 263                                 return -ESRCH;
 264                         }
 265                         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
 266                         up_read(&sb_dqopt(sb)->dqptr_sem);
 267                         if (copy_to_user(addr, &fmt, sizeof(fmt)))
 268                                 return -EFAULT;
 269                         return 0;
 270                 }
 271                 case Q_GETINFO: {
 272                         struct if_dqinfo info;
 273
 274                         ret = sb->s_qcop->get_info(sb, type, &info);
 275                         if (ret)
 276                                 return ret;
 277                         if (copy_to_user(addr, &info, sizeof(info)))
 278                                 return -EFAULT;
 279                         return 0;
 280                 }
 281                 case Q_SETINFO: {
 282                         struct if_dqinfo info;
 283
 284                         if (copy_from_user(&info, addr, sizeof(info)))
 285                                 return -EFAULT;
 286                         return sb->s_qcop->set_info(sb, type, &info);
 287                 }
 288                 case Q_GETQUOTA: {
 289                         struct if_dqblk idq;
 290
 291                         ret = sb->s_qcop->get_dqblk(sb, type, id, &idq);
 292                         if (ret)
 293                                 return ret;
 294                         if (copy_to_user(addr, &idq, sizeof(idq)))
 295                                 return -EFAULT;
 296                         return 0;
 297                 }
 298                 case Q_SETQUOTA: {
 299                         struct if_dqblk idq;
 300
 301                         if (copy_from_user(&idq, addr, sizeof(idq)))
 302                                 return -EFAULT;
 303                         return sb->s_qcop->set_dqblk(sb, type, id, &idq);
 304                 }
 305                 case Q_SYNC:
 306                         if (sb)
 307                                 sync_quota_sb(sb, type);
 308                         else
 309                                 sync_dquots(type);
 310                         return 0;
 311
 312                 case Q_XQUOTAON:
 313                 case Q_XQUOTAOFF:
 314                 case Q_XQUOTARM: {
 315                         __u32 flags;
 316
 317                         if (copy_from_user(&flags, addr, sizeof(flags)))
 318                                 return -EFAULT;
 319                         return sb->s_qcop->set_xstate(sb, flags, cmd);
 320                 }
 321                 case Q_XGETQSTAT: {
 322                         struct fs_quota_stat fqs;
 323
 324                         if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
 325                                 return ret;
 326                         if (copy_to_user(addr, &fqs, sizeof(fqs)))
 327                                 return -EFAULT;
 328                         return 0;
 329                 }
 330                 case Q_XSETQLIM: {
 331                         struct fs_disk_quota fdq;
 332
 333                         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 334                                 return -EFAULT;
 335                        return sb->s_qcop->set_xquota(sb, type, id, &fdq);
 336                 }
 337                 case Q_XGETQUOTA: {
 338                         struct fs_disk_quota fdq;
 339
 340                         ret = sb->s_qcop->get_xquota(sb, type, id, &fdq);
 341                         if (ret)
 342                                 return ret;
 343                         if (copy_to_user(addr, &fdq, sizeof(fdq)))
 344                                 return -EFAULT;
 345                         return 0;
 346                 }
 347                 case Q_XQUOTASYNC:
 348                         return sb->s_qcop->quota_sync(sb, type);
 349                 /* We never reach here unless validity check is broken */
 350                 default:
 351                         BUG();
 352         }
 353         return 0;
 354 }
 355
 356 /*
 357  * look up a superblock on which quota ops will be performed
 358  * - use the name of a block device to find the superblock thereon
 359  */
 360 static struct super_block *quotactl_block(const char __user *special)
 361 {
 362 #ifdef CONFIG_BLOCK
 363         struct block_device *bdev;
 364         struct super_block *sb;
 365         char *tmp = getname(special);
 366
 367         if (IS_ERR(tmp))
 368                 return ERR_CAST(tmp);
 369         bdev = lookup_bdev(tmp);
 370         putname(tmp);
 371         if (IS_ERR(bdev))
 372                 return ERR_CAST(bdev);
 373         sb = get_super(bdev);
 374         bdput(bdev);
 375         if (!sb)
 376                 return ERR_PTR(-ENODEV);
 377
 378         return sb;
 379 #else
 380         return ERR_PTR(-ENODEV);
 381 #endif
 382 }
 383
 384 /*
 385  * This is the system call interface. This communicates with
 386  * the user-level programs. Currently this only supports diskquota
 387  * calls. Maybe we need to add the process quotas etc. in the future,
 388  * but we probably should use rlimits for that.
 389  */
 390 SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
 391                 qid_t, id, void __user *, addr)
 392 {
 393         uint cmds, type;
 394         struct super_block *sb = NULL;
 395         int ret;
 396
 397         cmds = cmd >> SUBCMDSHIFT;
 398         type = cmd & SUBCMDMASK;
 399
 400         if (cmds != Q_SYNC || special) {
 401                 sb = quotactl_block(special);
 402                 if (IS_ERR(sb))
 403                         return PTR_ERR(sb);
 404         }
 405
 406         ret = check_quotactl_valid(sb, type, cmds, id);
 407         if (ret >= 0)
 408                 ret = do_quotactl(sb, type, cmds, id, addr);
 409         if (sb)
 410                 drop_super(sb);
 411
 412         return ret;
 413 }
 414
 415 #if defined(CONFIG_COMPAT_FOR_U64_ALIGNMENT)
 416 /*
 417  * This code works only for 32 bit quota tools over 64 bit OS (x86_64, ia64)
 418  * and is necessary due to alignment problems.
 419  */
 420 struct compat_if_dqblk {
 421         compat_u64 dqb_bhardlimit;
 422         compat_u64 dqb_bsoftlimit;
 423         compat_u64 dqb_curspace;
 424         compat_u64 dqb_ihardlimit;
 425         compat_u64 dqb_isoftlimit;
 426         compat_u64 dqb_curinodes;
 427         compat_u64 dqb_btime;
 428         compat_u64 dqb_itime;
 429         compat_uint_t dqb_valid;
 430 };
 431
 432 /* XFS structures */
 433 struct compat_fs_qfilestat {
 434         compat_u64 dqb_bhardlimit;
 435         compat_u64 qfs_nblks;
 436         compat_uint_t qfs_nextents;
 437 };
 438
 439 struct compat_fs_quota_stat {
 440         __s8            qs_version;
 441         __u16           qs_flags;
 442         __s8            qs_pad;
 443         struct compat_fs_qfilestat      qs_uquota;
 444         struct compat_fs_qfilestat      qs_gquota;
 445         compat_uint_t   qs_incoredqs;
 446         compat_int_t    qs_btimelimit;
 447         compat_int_t    qs_itimelimit;
 448         compat_int_t    qs_rtbtimelimit;
 449         __u16           qs_bwarnlimit;
 450         __u16           qs_iwarnlimit;
 451 };
 452
 453 asmlinkage long sys32_quotactl(unsigned int cmd, const char __user *special,
 454                                                 qid_t id, void __user *addr)
 455 {
 456         unsigned int cmds;
 457         struct if_dqblk __user *dqblk;
 458         struct compat_if_dqblk __user *compat_dqblk;
 459         struct fs_quota_stat __user *fsqstat;
 460         struct compat_fs_quota_stat __user *compat_fsqstat;
 461         compat_uint_t data;
 462         u16 xdata;
 463         long ret;
 464
 465         cmds = cmd >> SUBCMDSHIFT;
 466
 467         switch (cmds) {
 468         case Q_GETQUOTA:
 469                 dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
 470                 compat_dqblk = addr;
 471                 ret = sys_quotactl(cmd, special, id, dqblk);
 472                 if (ret)
 473                         break;
 474                 if (copy_in_user(compat_dqblk, dqblk, sizeof(*compat_dqblk)) ||
 475                         get_user(data, &dqblk->dqb_valid) ||
 476                         put_user(data, &compat_dqblk->dqb_valid))
 477                         ret = -EFAULT;
 478                 break;
 479         case Q_SETQUOTA:
 480                 dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
 481                 compat_dqblk = addr;
 482                 ret = -EFAULT;
 483                 if (copy_in_user(dqblk, compat_dqblk, sizeof(*compat_dqblk)) ||
 484                         get_user(data, &compat_dqblk->dqb_valid) ||
 485                         put_user(data, &dqblk->dqb_valid))
 486                         break;
 487                 ret = sys_quotactl(cmd, special, id, dqblk);
 488                 break;
 489         case Q_XGETQSTAT:
 490                 fsqstat = compat_alloc_user_space(sizeof(struct fs_quota_stat));
 491                 compat_fsqstat = addr;
 492                 ret = sys_quotactl(cmd, special, id, fsqstat);
 493                 if (ret)
 494                         break;
 495                 ret = -EFAULT;
 496                 /* Copying qs_version, qs_flags, qs_pad */
 497                 if (copy_in_user(compat_fsqstat, fsqstat,
 498                         offsetof(struct compat_fs_quota_stat, qs_uquota)))
 499                         break;
 500                 /* Copying qs_uquota */
 501                 if (copy_in_user(&compat_fsqstat->qs_uquota,
 502                         &fsqstat->qs_uquota,
 503                         sizeof(compat_fsqstat->qs_uquota)) ||
 504                         get_user(data, &fsqstat->qs_uquota.qfs_nextents) ||
 505                         put_user(data, &compat_fsqstat->qs_uquota.qfs_nextents))
 506                         break;
 507                 /* Copying qs_gquota */
 508                 if (copy_in_user(&compat_fsqstat->qs_gquota,
 509                         &fsqstat->qs_gquota,
 510                         sizeof(compat_fsqstat->qs_gquota)) ||
 511                         get_user(data, &fsqstat->qs_gquota.qfs_nextents) ||
 512                         put_user(data, &compat_fsqstat->qs_gquota.qfs_nextents))
 513                         break;
 514                 /* Copying the rest */
 515                 if (copy_in_user(&compat_fsqstat->qs_incoredqs,
 516                         &fsqstat->qs_incoredqs,
 517                         sizeof(struct compat_fs_quota_stat) -
 518                         offsetof(struct compat_fs_quota_stat, qs_incoredqs)) ||
 519                         get_user(xdata, &fsqstat->qs_iwarnlimit) ||
 520                         put_user(xdata, &compat_fsqstat->qs_iwarnlimit))
 521                         break;
 522                 ret = 0;
 523                 break;
 524         default:
 525                 ret = sys_quotactl(cmd, special, id, addr);
 526         }
 527         return ret;
 528 }
 529 #endif
 530
 531
 532 #ifdef CONFIG_QUOTA_NETLINK_INTERFACE
 533
 534 /* Netlink family structure for quota */
 535 static struct genl_family quota_genl_family = {
 536         .id = GENL_ID_GENERATE,
 537         .hdrsize = 0,
 538         .name = "VFS_DQUOT",
 539         .version = 1,
 540         .maxattr = QUOTA_NL_A_MAX,
 541 };
 542
 543 /**
 544  * quota_send_warning - Send warning to userspace about exceeded quota
 545  * @type: The quota type: USRQQUOTA, GRPQUOTA,...
 546  * @id: The user or group id of the quota that was exceeded
 547  * @dev: The device on which the fs is mounted (sb->s_dev)
 548  * @warntype: The type of the warning: QUOTA_NL_...
 549  *
 550  * This can be used by filesystems (including those which don't use
 551  * dquot) to send a message to userspace relating to quota limits.
 552  *
 553  */
 554
 555 void quota_send_warning(short type, unsigned int id, dev_t dev,
 556                         const char warntype)
 557 {
 558         static atomic_t seq;
 559         struct sk_buff *skb;
 560         void *msg_head;
 561         int ret;
 562         int msg_size = 4 * nla_total_size(sizeof(u32)) +
 563                        2 * nla_total_size(sizeof(u64));
 564
 565         /* We have to allocate using GFP_NOFS as we are called from a
 566          * filesystem performing write and thus further recursion into
 567          * the fs to free some data could cause deadlocks. */
 568         skb = genlmsg_new(msg_size, GFP_NOFS);
 569         if (!skb) {
 570                 printk(KERN_ERR
 571                   "VFS: Not enough memory to send quota warning.\n");
 572                 return;
 573         }
 574         msg_head = genlmsg_put(skb, 0, atomic_add_return(1, &seq),
 575                         &quota_genl_family, 0, QUOTA_NL_C_WARNING);
 576         if (!msg_head) {
 577                 printk(KERN_ERR
 578                   "VFS: Cannot store netlink header in quota warning.\n");
 579                 goto err_out;
 580         }
 581         ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, type);
 582         if (ret)
 583                 goto attr_err_out;
 584         ret = nla_put_u64(skb, QUOTA_NL_A_EXCESS_ID, id);
 585         if (ret)
 586                 goto attr_err_out;
 587         ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype);
 588         if (ret)
 589                 goto attr_err_out;
 590         ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MAJOR, MAJOR(dev));
 591         if (ret)
 592                 goto attr_err_out;
 593         ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR, MINOR(dev));
 594         if (ret)
 595                 goto attr_err_out;
 596         ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID, current_uid());
 597         if (ret)
 598                 goto attr_err_out;
 599         genlmsg_end(skb, msg_head);
 600
 601         genlmsg_multicast(skb, 0, quota_genl_family.id, GFP_NOFS);
 602         return;
 603 attr_err_out:
 604         printk(KERN_ERR "VFS: Not enough space to compose quota message!\n");
 605 err_out:
 606         kfree_skb(skb);
 607 }
 608 EXPORT_SYMBOL(quota_send_warning);
 609
 610 static int __init quota_init(void)
 611 {
 612         if (genl_register_family(&quota_genl_family) != 0)
 613                 printk(KERN_ERR
 614                        "VFS: Failed to create quota netlink interface.\n");
 615         return 0;
 616 };
 617
 618 module_init(quota_init);
 619 #endif
 620