fs/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
  22 /* Check validity of generic quotactl commands */
  23 static int generic_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
  24 {
  25         if (type >= MAXQUOTAS)
  26                 return -EINVAL;
  27         if (!sb && cmd != Q_SYNC)
  28                 return -ENODEV;
  29         /* Is operation supported? */
  30         if (sb && !sb->s_qcop)
  31                 return -ENOSYS;
  32
  33         switch (cmd) {
  34                 case Q_GETFMT:
  35                         break;
  36                 case Q_QUOTAON:
  37                         if (!sb->s_qcop->quota_on)
  38                                 return -ENOSYS;
  39                         break;
  40                 case Q_QUOTAOFF:
  41                         if (!sb->s_qcop->quota_off)
  42                                 return -ENOSYS;
  43                         break;
  44                 case Q_SETINFO:
  45                         if (!sb->s_qcop->set_info)
  46                                 return -ENOSYS;
  47                         break;
  48                 case Q_GETINFO:
  49                         if (!sb->s_qcop->get_info)
  50                                 return -ENOSYS;
  51                         break;
  52                 case Q_SETQUOTA:
  53                         if (!sb->s_qcop->set_dqblk)
  54                                 return -ENOSYS;
  55                         break;
  56                 case Q_GETQUOTA:
  57                         if (!sb->s_qcop->get_dqblk)
  58                                 return -ENOSYS;
  59                         break;
  60                 case Q_SYNC:
  61                         if (sb && !sb->s_qcop->quota_sync)
  62                                 return -ENOSYS;
  63                         break;
  64                 default:
  65                         return -EINVAL;
  66         }
  67
  68         /* Is quota turned on for commands which need it? */
  69         switch (cmd) {
  70                 case Q_GETFMT:
  71                 case Q_GETINFO:
  72                 case Q_SETINFO:
  73                 case Q_SETQUOTA:
  74                 case Q_GETQUOTA:
  75                         /* This is just informative test so we are satisfied without a lock */
  76                         if (!sb_has_quota_enabled(sb, type))
  77                                 return -ESRCH;
  78         }
  79
  80         /* Check privileges */
  81         if (cmd == Q_GETQUOTA) {
  82                 if (((type == USRQUOTA && current->euid != id) ||
  83                      (type == GRPQUOTA && !in_egroup_p(id))) &&
  84                     !capable(CAP_SYS_ADMIN))
  85                         return -EPERM;
  86         }
  87         else if (cmd != Q_GETFMT && cmd != Q_SYNC && cmd != Q_GETINFO)
  88                 if (!capable(CAP_SYS_ADMIN))
  89                         return -EPERM;
  90
  91         return 0;
  92 }
  93
  94 /* Check validity of XFS Quota Manager commands */
  95 static int xqm_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
  96 {
  97         if (type >= XQM_MAXQUOTAS)
  98                 return -EINVAL;
  99         if (!sb)
 100                 return -ENODEV;
 101         if (!sb->s_qcop)
 102                 return -ENOSYS;
 103
 104         switch (cmd) {
 105                 case Q_XQUOTAON:
 106                 case Q_XQUOTAOFF:
 107                 case Q_XQUOTARM:
 108                         if (!sb->s_qcop->set_xstate)
 109                                 return -ENOSYS;
 110                         break;
 111                 case Q_XGETQSTAT:
 112                         if (!sb->s_qcop->get_xstate)
 113                                 return -ENOSYS;
 114                         break;
 115                 case Q_XSETQLIM:
 116                         if (!sb->s_qcop->set_xquota)
 117                                 return -ENOSYS;
 118                         break;
 119                 case Q_XGETQUOTA:
 120                         if (!sb->s_qcop->get_xquota)
 121                                 return -ENOSYS;
 122                         break;
 123                 case Q_XQUOTASYNC:
 124                         if (!sb->s_qcop->quota_sync)
 125                                 return -ENOSYS;
 126                         break;
 127                 default:
 128                         return -EINVAL;
 129         }
 130
 131         /* Check privileges */
 132         if (cmd == Q_XGETQUOTA) {
 133                 if (((type == XQM_USRQUOTA && current->euid != id) ||
 134                      (type == XQM_GRPQUOTA && !in_egroup_p(id))) &&
 135                      !capable(CAP_SYS_ADMIN))
 136                         return -EPERM;
 137         } else if (cmd != Q_XGETQSTAT && cmd != Q_XQUOTASYNC) {
 138                 if (!capable(CAP_SYS_ADMIN))
 139                         return -EPERM;
 140         }
 141
 142         return 0;
 143 }
 144
 145 static int check_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
 146 {
 147         int error;
 148
 149         if (XQM_COMMAND(cmd))
 150                 error = xqm_quotactl_valid(sb, type, cmd, id);
 151         else
 152                 error = generic_quotactl_valid(sb, type, cmd, id);
 153         if (!error)
 154                 error = security_quotactl(cmd, type, id, sb);
 155         return error;
 156 }
 157
 158 static void quota_sync_sb(struct super_block *sb, int type)
 159 {
 160         int cnt;
 161
 162         sb->s_qcop->quota_sync(sb, type);
 163         /* This is not very clever (and fast) but currently I don't know about
 164          * any other simple way of getting quota data to disk and we must get
 165          * them there for userspace to be visible... */
 166         if (sb->s_op->sync_fs)
 167                 sb->s_op->sync_fs(sb, 1);
 168         sync_blockdev(sb->s_bdev);
 169
 170         /*
 171          * Now when everything is written we can discard the pagecache so
 172          * that userspace sees the changes.
 173          */
 174         mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
 175         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 176                 if (type != -1 && cnt != type)
 177                         continue;
 178                 if (!sb_has_quota_enabled(sb, cnt))
 179                         continue;
 180                 mutex_lock_nested(&sb_dqopt(sb)->files[cnt]->i_mutex, I_MUTEX_QUOTA);
 181                 truncate_inode_pages(&sb_dqopt(sb)->files[cnt]->i_data, 0);
 182                 mutex_unlock(&sb_dqopt(sb)->files[cnt]->i_mutex);
 183         }
 184         mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
 185 }
 186
 187 void sync_dquots(struct super_block *sb, int type)
 188 {
 189         int cnt;
 190
 191         if (sb) {
 192                 if (sb->s_qcop->quota_sync)
 193                         quota_sync_sb(sb, type);
 194                 return;
 195         }
 196
 197         spin_lock(&sb_lock);
 198 restart:
 199         list_for_each_entry(sb, &super_blocks, s_list) {
 200                 /* This test just improves performance so it needn't be reliable... */
 201                 for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 202                         if (type != -1 && type != cnt)
 203                                 continue;
 204                         if (!sb_has_quota_enabled(sb, cnt))
 205                                 continue;
 206                         if (!info_dirty(&sb_dqopt(sb)->info[cnt]) &&
 207                             list_empty(&sb_dqopt(sb)->info[cnt].dqi_dirty_list))
 208                                 continue;
 209                         break;
 210                 }
 211                 if (cnt == MAXQUOTAS)
 212                         continue;
 213                 sb->s_count++;
 214                 spin_unlock(&sb_lock);
 215                 down_read(&sb->s_umount);
 216                 if (sb->s_root && sb->s_qcop->quota_sync)
 217                         quota_sync_sb(sb, type);
 218                 up_read(&sb->s_umount);
 219                 spin_lock(&sb_lock);
 220                 if (__put_super_and_need_restart(sb))
 221                         goto restart;
 222         }
 223         spin_unlock(&sb_lock);
 224 }
 225
 226 /* Copy parameters and call proper function */
 227 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, void __user *addr)
 228 {
 229         int ret;
 230
 231         switch (cmd) {
 232                 case Q_QUOTAON: {
 233                         char *pathname;
 234
 235                         if (IS_ERR(pathname = getname(addr)))
 236                                 return PTR_ERR(pathname);
 237                         ret = sb->s_qcop->quota_on(sb, type, id, pathname, 0);
 238                         putname(pathname);
 239                         return ret;
 240                 }
 241                 case Q_QUOTAOFF:
 242                         return sb->s_qcop->quota_off(sb, type, 0);
 243
 244                 case Q_GETFMT: {
 245                         __u32 fmt;
 246
 247                         down_read(&sb_dqopt(sb)->dqptr_sem);
 248                         if (!sb_has_quota_enabled(sb, type)) {
 249                                 up_read(&sb_dqopt(sb)->dqptr_sem);
 250                                 return -ESRCH;
 251                         }
 252                         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
 253                         up_read(&sb_dqopt(sb)->dqptr_sem);
 254                         if (copy_to_user(addr, &fmt, sizeof(fmt)))
 255                                 return -EFAULT;
 256                         return 0;
 257                 }
 258                 case Q_GETINFO: {
 259                         struct if_dqinfo info;
 260
 261                         if ((ret = sb->s_qcop->get_info(sb, type, &info)))
 262                                 return ret;
 263                         if (copy_to_user(addr, &info, sizeof(info)))
 264                                 return -EFAULT;
 265                         return 0;
 266                 }
 267                 case Q_SETINFO: {
 268                         struct if_dqinfo info;
 269
 270                         if (copy_from_user(&info, addr, sizeof(info)))
 271                                 return -EFAULT;
 272                         return sb->s_qcop->set_info(sb, type, &info);
 273                 }
 274                 case Q_GETQUOTA: {
 275                         struct if_dqblk idq;
 276
 277                         if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)))
 278                                 return ret;
 279                         if (copy_to_user(addr, &idq, sizeof(idq)))
 280                                 return -EFAULT;
 281                         return 0;
 282                 }
 283                 case Q_SETQUOTA: {
 284                         struct if_dqblk idq;
 285
 286                         if (copy_from_user(&idq, addr, sizeof(idq)))
 287                                 return -EFAULT;
 288                         return sb->s_qcop->set_dqblk(sb, type, id, &idq);
 289                 }
 290                 case Q_SYNC:
 291                         sync_dquots(sb, type);
 292                         return 0;
 293
 294                 case Q_XQUOTAON:
 295                 case Q_XQUOTAOFF:
 296                 case Q_XQUOTARM: {
 297                         __u32 flags;
 298
 299                         if (copy_from_user(&flags, addr, sizeof(flags)))
 300                                 return -EFAULT;
 301                         return sb->s_qcop->set_xstate(sb, flags, cmd);
 302                 }
 303                 case Q_XGETQSTAT: {
 304                         struct fs_quota_stat fqs;
 305
 306                         if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
 307                                 return ret;
 308                         if (copy_to_user(addr, &fqs, sizeof(fqs)))
 309                                 return -EFAULT;
 310                         return 0;
 311                 }
 312                 case Q_XSETQLIM: {
 313                         struct fs_disk_quota fdq;
 314
 315                         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 316                                 return -EFAULT;
 317                        return sb->s_qcop->set_xquota(sb, type, id, &fdq);
 318                 }
 319                 case Q_XGETQUOTA: {
 320                         struct fs_disk_quota fdq;
 321
 322                         if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq)))
 323                                 return ret;
 324                         if (copy_to_user(addr, &fdq, sizeof(fdq)))
 325                                 return -EFAULT;
 326                         return 0;
 327                 }
 328                 case Q_XQUOTASYNC:
 329                         return sb->s_qcop->quota_sync(sb, type);
 330                 /* We never reach here unless validity check is broken */
 331                 default:
 332                         BUG();
 333         }
 334         return 0;
 335 }
 336
 337 /*
 338  * look up a superblock on which quota ops will be performed
 339  * - use the name of a block device to find the superblock thereon
 340  */
 341 static inline struct super_block *quotactl_block(const char __user *special)
 342 {
 343 #ifdef CONFIG_BLOCK
 344         struct block_device *bdev;
 345         struct super_block *sb;
 346         char *tmp = getname(special);
 347
 348         if (IS_ERR(tmp))
 349                 return ERR_CAST(tmp);
 350         bdev = lookup_bdev(tmp);
 351         putname(tmp);
 352         if (IS_ERR(bdev))
 353                 return ERR_CAST(bdev);
 354         sb = get_super(bdev);
 355         bdput(bdev);
 356         if (!sb)
 357                 return ERR_PTR(-ENODEV);
 358
 359         return sb;
 360 #else
 361         return ERR_PTR(-ENODEV);
 362 #endif
 363 }
 364
 365 /*
 366  * This is the system call interface. This communicates with
 367  * the user-level programs. Currently this only supports diskquota
 368  * calls. Maybe we need to add the process quotas etc. in the future,
 369  * but we probably should use rlimits for that.
 370  */
 371 asmlinkage long sys_quotactl(unsigned int cmd, const char __user *special, qid_t id, void __user *addr)
 372 {
 373         uint cmds, type;
 374         struct super_block *sb = NULL;
 375         int ret;
 376
 377         cmds = cmd >> SUBCMDSHIFT;
 378         type = cmd & SUBCMDMASK;
 379
 380         if (cmds != Q_SYNC || special) {
 381                 sb = quotactl_block(special);
 382                 if (IS_ERR(sb))
 383                         return PTR_ERR(sb);
 384         }
 385
 386         ret = check_quotactl_valid(sb, type, cmds, id);
 387         if (ret >= 0)
 388                 ret = do_quotactl(sb, type, cmds, id, addr);
 389         if (sb)
 390                 drop_super(sb);
 391
 392         return ret;
 393 }
 394
 395 #if defined(CONFIG_COMPAT_FOR_U64_ALIGNMENT)
 396 /*
 397  * This code works only for 32 bit quota tools over 64 bit OS (x86_64, ia64)
 398  * and is necessary due to alignment problems.
 399  */
 400 struct compat_if_dqblk {
 401         compat_u64 dqb_bhardlimit;
 402         compat_u64 dqb_bsoftlimit;
 403         compat_u64 dqb_curspace;
 404         compat_u64 dqb_ihardlimit;
 405         compat_u64 dqb_isoftlimit;
 406         compat_u64 dqb_curinodes;
 407         compat_u64 dqb_btime;
 408         compat_u64 dqb_itime;
 409         compat_uint_t dqb_valid;
 410 };
 411
 412 /* XFS structures */
 413 struct compat_fs_qfilestat {
 414         compat_u64 dqb_bhardlimit;
 415         compat_u64 qfs_nblks;
 416         compat_uint_t qfs_nextents;
 417 };
 418
 419 struct compat_fs_quota_stat {
 420         __s8            qs_version;
 421         __u16           qs_flags;
 422         __s8            qs_pad;
 423         struct compat_fs_qfilestat      qs_uquota;
 424         struct compat_fs_qfilestat      qs_gquota;
 425         compat_uint_t   qs_incoredqs;
 426         compat_int_t    qs_btimelimit;
 427         compat_int_t    qs_itimelimit;
 428         compat_int_t    qs_rtbtimelimit;
 429         __u16           qs_bwarnlimit;
 430         __u16           qs_iwarnlimit;
 431 };
 432
 433 asmlinkage long sys32_quotactl(unsigned int cmd, const char __user *special,
 434                                                 qid_t id, void __user *addr)
 435 {
 436         unsigned int cmds;
 437         struct if_dqblk __user *dqblk;
 438         struct compat_if_dqblk __user *compat_dqblk;
 439         struct fs_quota_stat __user *fsqstat;
 440         struct compat_fs_quota_stat __user *compat_fsqstat;
 441         compat_uint_t data;
 442         u16 xdata;
 443         long ret;
 444
 445         cmds = cmd >> SUBCMDSHIFT;
 446
 447         switch (cmds) {
 448         case Q_GETQUOTA:
 449                 dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
 450                 compat_dqblk = addr;
 451                 ret = sys_quotactl(cmd, special, id, dqblk);
 452                 if (ret)
 453                         break;
 454                 if (copy_in_user(compat_dqblk, dqblk, sizeof(*compat_dqblk)) ||
 455                         get_user(data, &dqblk->dqb_valid) ||
 456                         put_user(data, &compat_dqblk->dqb_valid))
 457                         ret = -EFAULT;
 458                 break;
 459         case Q_SETQUOTA:
 460                 dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
 461                 compat_dqblk = addr;
 462                 ret = -EFAULT;
 463                 if (copy_in_user(dqblk, compat_dqblk, sizeof(*compat_dqblk)) ||
 464                         get_user(data, &compat_dqblk->dqb_valid) ||
 465                         put_user(data, &dqblk->dqb_valid))
 466                         break;
 467                 ret = sys_quotactl(cmd, special, id, dqblk);
 468                 break;
 469         case Q_XGETQSTAT:
 470                 fsqstat = compat_alloc_user_space(sizeof(struct fs_quota_stat));
 471                 compat_fsqstat = addr;
 472                 ret = sys_quotactl(cmd, special, id, fsqstat);
 473                 if (ret)
 474                         break;
 475                 ret = -EFAULT;
 476                 /* Copying qs_version, qs_flags, qs_pad */
 477                 if (copy_in_user(compat_fsqstat, fsqstat,
 478                         offsetof(struct compat_fs_quota_stat, qs_uquota)))
 479                         break;
 480                 /* Copying qs_uquota */
 481                 if (copy_in_user(&compat_fsqstat->qs_uquota,
 482                         &fsqstat->qs_uquota,
 483                         sizeof(compat_fsqstat->qs_uquota)) ||
 484                         get_user(data, &fsqstat->qs_uquota.qfs_nextents) ||
 485                         put_user(data, &compat_fsqstat->qs_uquota.qfs_nextents))
 486                         break;
 487                 /* Copying qs_gquota */
 488                 if (copy_in_user(&compat_fsqstat->qs_gquota,
 489                         &fsqstat->qs_gquota,
 490                         sizeof(compat_fsqstat->qs_gquota)) ||
 491                         get_user(data, &fsqstat->qs_gquota.qfs_nextents) ||
 492                         put_user(data, &compat_fsqstat->qs_gquota.qfs_nextents))
 493                         break;
 494                 /* Copying the rest */
 495                 if (copy_in_user(&compat_fsqstat->qs_incoredqs,
 496                         &fsqstat->qs_incoredqs,
 497                         sizeof(struct compat_fs_quota_stat) -
 498                         offsetof(struct compat_fs_quota_stat, qs_incoredqs)) ||
 499                         get_user(xdata, &fsqstat->qs_iwarnlimit) ||
 500                         put_user(xdata, &compat_fsqstat->qs_iwarnlimit))
 501                         break;
 502                 ret = 0;
 503                 break;
 504         default:
 505                 ret = sys_quotactl(cmd, special, id, addr);
 506         }
 507         return ret;
 508 }
 509 #endif