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, dirty;
 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, dirty = 0; cnt < MAXQUOTAS; cnt++)
 202                         if ((type == cnt || type == -1) && sb_has_quota_enabled(sb, cnt)
 203                             && info_any_dirty(&sb_dqopt(sb)->info[cnt]))
 204                                 dirty = 1;
 205                 if (!dirty)
 206                         continue;
 207                 sb->s_count++;
 208                 spin_unlock(&sb_lock);
 209                 down_read(&sb->s_umount);
 210                 if (sb->s_root && sb->s_qcop->quota_sync)
 211                         quota_sync_sb(sb, type);
 212                 up_read(&sb->s_umount);
 213                 spin_lock(&sb_lock);
 214                 if (__put_super_and_need_restart(sb))
 215                         goto restart;
 216         }
 217         spin_unlock(&sb_lock);
 218 }
 219
 220 /* Copy parameters and call proper function */
 221 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, void __user *addr)
 222 {
 223         int ret;
 224
 225         switch (cmd) {
 226                 case Q_QUOTAON: {
 227                         char *pathname;
 228
 229                         if (IS_ERR(pathname = getname(addr)))
 230                                 return PTR_ERR(pathname);
 231                         ret = sb->s_qcop->quota_on(sb, type, id, pathname, 0);
 232                         putname(pathname);
 233                         return ret;
 234                 }
 235                 case Q_QUOTAOFF:
 236                         return sb->s_qcop->quota_off(sb, type, 0);
 237
 238                 case Q_GETFMT: {
 239                         __u32 fmt;
 240
 241                         down_read(&sb_dqopt(sb)->dqptr_sem);
 242                         if (!sb_has_quota_enabled(sb, type)) {
 243                                 up_read(&sb_dqopt(sb)->dqptr_sem);
 244                                 return -ESRCH;
 245                         }
 246                         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
 247                         up_read(&sb_dqopt(sb)->dqptr_sem);
 248                         if (copy_to_user(addr, &fmt, sizeof(fmt)))
 249                                 return -EFAULT;
 250                         return 0;
 251                 }
 252                 case Q_GETINFO: {
 253                         struct if_dqinfo info;
 254
 255                         if ((ret = sb->s_qcop->get_info(sb, type, &info)))
 256                                 return ret;
 257                         if (copy_to_user(addr, &info, sizeof(info)))
 258                                 return -EFAULT;
 259                         return 0;
 260                 }
 261                 case Q_SETINFO: {
 262                         struct if_dqinfo info;
 263
 264                         if (copy_from_user(&info, addr, sizeof(info)))
 265                                 return -EFAULT;
 266                         return sb->s_qcop->set_info(sb, type, &info);
 267                 }
 268                 case Q_GETQUOTA: {
 269                         struct if_dqblk idq;
 270
 271                         if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)))
 272                                 return ret;
 273                         if (copy_to_user(addr, &idq, sizeof(idq)))
 274                                 return -EFAULT;
 275                         return 0;
 276                 }
 277                 case Q_SETQUOTA: {
 278                         struct if_dqblk idq;
 279
 280                         if (copy_from_user(&idq, addr, sizeof(idq)))
 281                                 return -EFAULT;
 282                         return sb->s_qcop->set_dqblk(sb, type, id, &idq);
 283                 }
 284                 case Q_SYNC:
 285                         sync_dquots(sb, type);
 286                         return 0;
 287
 288                 case Q_XQUOTAON:
 289                 case Q_XQUOTAOFF:
 290                 case Q_XQUOTARM: {
 291                         __u32 flags;
 292
 293                         if (copy_from_user(&flags, addr, sizeof(flags)))
 294                                 return -EFAULT;
 295                         return sb->s_qcop->set_xstate(sb, flags, cmd);
 296                 }
 297                 case Q_XGETQSTAT: {
 298                         struct fs_quota_stat fqs;
 299
 300                         if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
 301                                 return ret;
 302                         if (copy_to_user(addr, &fqs, sizeof(fqs)))
 303                                 return -EFAULT;
 304                         return 0;
 305                 }
 306                 case Q_XSETQLIM: {
 307                         struct fs_disk_quota fdq;
 308
 309                         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 310                                 return -EFAULT;
 311                        return sb->s_qcop->set_xquota(sb, type, id, &fdq);
 312                 }
 313                 case Q_XGETQUOTA: {
 314                         struct fs_disk_quota fdq;
 315
 316                         if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq)))
 317                                 return ret;
 318                         if (copy_to_user(addr, &fdq, sizeof(fdq)))
 319                                 return -EFAULT;
 320                         return 0;
 321                 }
 322                 case Q_XQUOTASYNC:
 323                         return sb->s_qcop->quota_sync(sb, type);
 324                 /* We never reach here unless validity check is broken */
 325                 default:
 326                         BUG();
 327         }
 328         return 0;
 329 }
 330
 331 /*
 332  * look up a superblock on which quota ops will be performed
 333  * - use the name of a block device to find the superblock thereon
 334  */
 335 static inline struct super_block *quotactl_block(const char __user *special)
 336 {
 337 #ifdef CONFIG_BLOCK
 338         struct block_device *bdev;
 339         struct super_block *sb;
 340         char *tmp = getname(special);
 341
 342         if (IS_ERR(tmp))
 343                 return ERR_CAST(tmp);
 344         bdev = lookup_bdev(tmp);
 345         putname(tmp);
 346         if (IS_ERR(bdev))
 347                 return ERR_CAST(bdev);
 348         sb = get_super(bdev);
 349         bdput(bdev);
 350         if (!sb)
 351                 return ERR_PTR(-ENODEV);
 352
 353         return sb;
 354 #else
 355         return ERR_PTR(-ENODEV);
 356 #endif
 357 }
 358
 359 /*
 360  * This is the system call interface. This communicates with
 361  * the user-level programs. Currently this only supports diskquota
 362  * calls. Maybe we need to add the process quotas etc. in the future,
 363  * but we probably should use rlimits for that.
 364  */
 365 asmlinkage long sys_quotactl(unsigned int cmd, const char __user *special, qid_t id, void __user *addr)
 366 {
 367         uint cmds, type;
 368         struct super_block *sb = NULL;
 369         int ret;
 370
 371         cmds = cmd >> SUBCMDSHIFT;
 372         type = cmd & SUBCMDMASK;
 373
 374         if (cmds != Q_SYNC || special) {
 375                 sb = quotactl_block(special);
 376                 if (IS_ERR(sb))
 377                         return PTR_ERR(sb);
 378         }
 379
 380         ret = check_quotactl_valid(sb, type, cmds, id);
 381         if (ret >= 0)
 382                 ret = do_quotactl(sb, type, cmds, id, addr);
 383         if (sb)
 384                 drop_super(sb);
 385
 386         return ret;
 387 }
 388
 389 #if defined(CONFIG_COMPAT_FOR_U64_ALIGNMENT)
 390 /*
 391  * This code works only for 32 bit quota tools over 64 bit OS (x86_64, ia64)
 392  * and is necessary due to alignment problems.
 393  */
 394 struct compat_if_dqblk {
 395         compat_u64 dqb_bhardlimit;
 396         compat_u64 dqb_bsoftlimit;
 397         compat_u64 dqb_curspace;
 398         compat_u64 dqb_ihardlimit;
 399         compat_u64 dqb_isoftlimit;
 400         compat_u64 dqb_curinodes;
 401         compat_u64 dqb_btime;
 402         compat_u64 dqb_itime;
 403         compat_uint_t dqb_valid;
 404 };
 405
 406 /* XFS structures */
 407 struct compat_fs_qfilestat {
 408         compat_u64 dqb_bhardlimit;
 409         compat_u64 qfs_nblks;
 410         compat_uint_t qfs_nextents;
 411 };
 412
 413 struct compat_fs_quota_stat {
 414         __s8            qs_version;
 415         __u16           qs_flags;
 416         __s8            qs_pad;
 417         struct compat_fs_qfilestat      qs_uquota;
 418         struct compat_fs_qfilestat      qs_gquota;
 419         compat_uint_t   qs_incoredqs;
 420         compat_int_t    qs_btimelimit;
 421         compat_int_t    qs_itimelimit;
 422         compat_int_t    qs_rtbtimelimit;
 423         __u16           qs_bwarnlimit;
 424         __u16           qs_iwarnlimit;
 425 };
 426
 427 asmlinkage long sys32_quotactl(unsigned int cmd, const char __user *special,
 428                                                 qid_t id, void __user *addr)
 429 {
 430         unsigned int cmds;
 431         struct if_dqblk __user *dqblk;
 432         struct compat_if_dqblk __user *compat_dqblk;
 433         struct fs_quota_stat __user *fsqstat;
 434         struct compat_fs_quota_stat __user *compat_fsqstat;
 435         compat_uint_t data;
 436         u16 xdata;
 437         long ret;
 438
 439         cmds = cmd >> SUBCMDSHIFT;
 440
 441         switch (cmds) {
 442         case Q_GETQUOTA:
 443                 dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
 444                 compat_dqblk = addr;
 445                 ret = sys_quotactl(cmd, special, id, dqblk);
 446                 if (ret)
 447                         break;
 448                 if (copy_in_user(compat_dqblk, dqblk, sizeof(*compat_dqblk)) ||
 449                         get_user(data, &dqblk->dqb_valid) ||
 450                         put_user(data, &compat_dqblk->dqb_valid))
 451                         ret = -EFAULT;
 452                 break;
 453         case Q_SETQUOTA:
 454                 dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
 455                 compat_dqblk = addr;
 456                 ret = -EFAULT;
 457                 if (copy_in_user(dqblk, compat_dqblk, sizeof(*compat_dqblk)) ||
 458                         get_user(data, &compat_dqblk->dqb_valid) ||
 459                         put_user(data, &dqblk->dqb_valid))
 460                         break;
 461                 ret = sys_quotactl(cmd, special, id, dqblk);
 462                 break;
 463         case Q_XGETQSTAT:
 464                 fsqstat = compat_alloc_user_space(sizeof(struct fs_quota_stat));
 465                 compat_fsqstat = addr;
 466                 ret = sys_quotactl(cmd, special, id, fsqstat);
 467                 if (ret)
 468                         break;
 469                 ret = -EFAULT;
 470                 /* Copying qs_version, qs_flags, qs_pad */
 471                 if (copy_in_user(compat_fsqstat, fsqstat,
 472                         offsetof(struct compat_fs_quota_stat, qs_uquota)))
 473                         break;
 474                 /* Copying qs_uquota */
 475                 if (copy_in_user(&compat_fsqstat->qs_uquota,
 476                         &fsqstat->qs_uquota,
 477                         sizeof(compat_fsqstat->qs_uquota)) ||
 478                         get_user(data, &fsqstat->qs_uquota.qfs_nextents) ||
 479                         put_user(data, &compat_fsqstat->qs_uquota.qfs_nextents))
 480                         break;
 481                 /* Copying qs_gquota */
 482                 if (copy_in_user(&compat_fsqstat->qs_gquota,
 483                         &fsqstat->qs_gquota,
 484                         sizeof(compat_fsqstat->qs_gquota)) ||
 485                         get_user(data, &fsqstat->qs_gquota.qfs_nextents) ||
 486                         put_user(data, &compat_fsqstat->qs_gquota.qfs_nextents))
 487                         break;
 488                 /* Copying the rest */
 489                 if (copy_in_user(&compat_fsqstat->qs_incoredqs,
 490                         &fsqstat->qs_incoredqs,
 491                         sizeof(struct compat_fs_quota_stat) -
 492                         offsetof(struct compat_fs_quota_stat, qs_incoredqs)) ||
 493                         get_user(xdata, &fsqstat->qs_iwarnlimit) ||
 494                         put_user(xdata, &compat_fsqstat->qs_iwarnlimit))
 495                         break;
 496                 ret = 0;
 497                 break;
 498         default:
 499                 ret = sys_quotactl(cmd, special, id, addr);
 500         }
 501         return ret;
 502 }
 503 #endif