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_active(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
 164         if (sb_dqopt(sb)->flags & DQUOT_QUOTA_SYS_FILE)
 165                 return;
 166         /* This is not very clever (and fast) but currently I don't know about
 167          * any other simple way of getting quota data to disk and we must get
 168          * them there for userspace to be visible... */
 169         if (sb->s_op->sync_fs)
 170                 sb->s_op->sync_fs(sb, 1);
 171         sync_blockdev(sb->s_bdev);
 172
 173         /*
 174          * Now when everything is written we can discard the pagecache so
 175          * that userspace sees the changes.
 176          */
 177         mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
 178         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 179                 if (type != -1 && cnt != type)
 180                         continue;
 181                 if (!sb_has_quota_active(sb, cnt))
 182                         continue;
 183                 mutex_lock_nested(&sb_dqopt(sb)->files[cnt]->i_mutex, I_MUTEX_QUOTA);
 184                 truncate_inode_pages(&sb_dqopt(sb)->files[cnt]->i_data, 0);
 185                 mutex_unlock(&sb_dqopt(sb)->files[cnt]->i_mutex);
 186         }
 187         mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
 188 }
 189
 190 void sync_dquots(struct super_block *sb, int type)
 191 {
 192         int cnt;
 193
 194         if (sb) {
 195                 if (sb->s_qcop->quota_sync)
 196                         quota_sync_sb(sb, type);
 197                 return;
 198         }
 199
 200         spin_lock(&sb_lock);
 201 restart:
 202         list_for_each_entry(sb, &super_blocks, s_list) {
 203                 /* This test just improves performance so it needn't be reliable... */
 204                 for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 205                         if (type != -1 && type != cnt)
 206                                 continue;
 207                         if (!sb_has_quota_active(sb, cnt))
 208                                 continue;
 209                         if (!info_dirty(&sb_dqopt(sb)->info[cnt]) &&
 210                             list_empty(&sb_dqopt(sb)->info[cnt].dqi_dirty_list))
 211                                 continue;
 212                         break;
 213                 }
 214                 if (cnt == MAXQUOTAS)
 215                         continue;
 216                 sb->s_count++;
 217                 spin_unlock(&sb_lock);
 218                 down_read(&sb->s_umount);
 219                 if (sb->s_root && sb->s_qcop->quota_sync)
 220                         quota_sync_sb(sb, type);
 221                 up_read(&sb->s_umount);
 222                 spin_lock(&sb_lock);
 223                 if (__put_super_and_need_restart(sb))
 224                         goto restart;
 225         }
 226         spin_unlock(&sb_lock);
 227 }
 228
 229 /* Copy parameters and call proper function */
 230 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, void __user *addr)
 231 {
 232         int ret;
 233
 234         switch (cmd) {
 235                 case Q_QUOTAON: {
 236                         char *pathname;
 237
 238                         if (IS_ERR(pathname = getname(addr)))
 239                                 return PTR_ERR(pathname);
 240                         ret = sb->s_qcop->quota_on(sb, type, id, pathname, 0);
 241                         putname(pathname);
 242                         return ret;
 243                 }
 244                 case Q_QUOTAOFF:
 245                         return sb->s_qcop->quota_off(sb, type, 0);
 246
 247                 case Q_GETFMT: {
 248                         __u32 fmt;
 249
 250                         down_read(&sb_dqopt(sb)->dqptr_sem);
 251                         if (!sb_has_quota_active(sb, type)) {
 252                                 up_read(&sb_dqopt(sb)->dqptr_sem);
 253                                 return -ESRCH;
 254                         }
 255                         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
 256                         up_read(&sb_dqopt(sb)->dqptr_sem);
 257                         if (copy_to_user(addr, &fmt, sizeof(fmt)))
 258                                 return -EFAULT;
 259                         return 0;
 260                 }
 261                 case Q_GETINFO: {
 262                         struct if_dqinfo info;
 263
 264                         if ((ret = sb->s_qcop->get_info(sb, type, &info)))
 265                                 return ret;
 266                         if (copy_to_user(addr, &info, sizeof(info)))
 267                                 return -EFAULT;
 268                         return 0;
 269                 }
 270                 case Q_SETINFO: {
 271                         struct if_dqinfo info;
 272
 273                         if (copy_from_user(&info, addr, sizeof(info)))
 274                                 return -EFAULT;
 275                         return sb->s_qcop->set_info(sb, type, &info);
 276                 }
 277                 case Q_GETQUOTA: {
 278                         struct if_dqblk idq;
 279
 280                         if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)))
 281                                 return ret;
 282                         if (copy_to_user(addr, &idq, sizeof(idq)))
 283                                 return -EFAULT;
 284                         return 0;
 285                 }
 286                 case Q_SETQUOTA: {
 287                         struct if_dqblk idq;
 288
 289                         if (copy_from_user(&idq, addr, sizeof(idq)))
 290                                 return -EFAULT;
 291                         return sb->s_qcop->set_dqblk(sb, type, id, &idq);
 292                 }
 293                 case Q_SYNC:
 294                         sync_dquots(sb, type);
 295                         return 0;
 296
 297                 case Q_XQUOTAON:
 298                 case Q_XQUOTAOFF:
 299                 case Q_XQUOTARM: {
 300                         __u32 flags;
 301
 302                         if (copy_from_user(&flags, addr, sizeof(flags)))
 303                                 return -EFAULT;
 304                         return sb->s_qcop->set_xstate(sb, flags, cmd);
 305                 }
 306                 case Q_XGETQSTAT: {
 307                         struct fs_quota_stat fqs;
 308
 309                         if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
 310                                 return ret;
 311                         if (copy_to_user(addr, &fqs, sizeof(fqs)))
 312                                 return -EFAULT;
 313                         return 0;
 314                 }
 315                 case Q_XSETQLIM: {
 316                         struct fs_disk_quota fdq;
 317
 318                         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 319                                 return -EFAULT;
 320                        return sb->s_qcop->set_xquota(sb, type, id, &fdq);
 321                 }
 322                 case Q_XGETQUOTA: {
 323                         struct fs_disk_quota fdq;
 324
 325                         if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq)))
 326                                 return ret;
 327                         if (copy_to_user(addr, &fdq, sizeof(fdq)))
 328                                 return -EFAULT;
 329                         return 0;
 330                 }
 331                 case Q_XQUOTASYNC:
 332                         return sb->s_qcop->quota_sync(sb, type);
 333                 /* We never reach here unless validity check is broken */
 334                 default:
 335                         BUG();
 336         }
 337         return 0;
 338 }
 339
 340 /*
 341  * look up a superblock on which quota ops will be performed
 342  * - use the name of a block device to find the superblock thereon
 343  */
 344 static inline struct super_block *quotactl_block(const char __user *special)
 345 {
 346 #ifdef CONFIG_BLOCK
 347         struct block_device *bdev;
 348         struct super_block *sb;
 349         char *tmp = getname(special);
 350
 351         if (IS_ERR(tmp))
 352                 return ERR_CAST(tmp);
 353         bdev = lookup_bdev(tmp);
 354         putname(tmp);
 355         if (IS_ERR(bdev))
 356                 return ERR_CAST(bdev);
 357         sb = get_super(bdev);
 358         bdput(bdev);
 359         if (!sb)
 360                 return ERR_PTR(-ENODEV);
 361
 362         return sb;
 363 #else
 364         return ERR_PTR(-ENODEV);
 365 #endif
 366 }
 367
 368 /*
 369  * This is the system call interface. This communicates with
 370  * the user-level programs. Currently this only supports diskquota
 371  * calls. Maybe we need to add the process quotas etc. in the future,
 372  * but we probably should use rlimits for that.
 373  */
 374 SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
 375                 qid_t, id, void __user *, addr)
 376 {
 377         uint cmds, type;
 378         struct super_block *sb = NULL;
 379         int ret;
 380
 381         cmds = cmd >> SUBCMDSHIFT;
 382         type = cmd & SUBCMDMASK;
 383
 384         if (cmds != Q_SYNC || special) {
 385                 sb = quotactl_block(special);
 386                 if (IS_ERR(sb))
 387                         return PTR_ERR(sb);
 388         }
 389
 390         ret = check_quotactl_valid(sb, type, cmds, id);
 391         if (ret >= 0)
 392                 ret = do_quotactl(sb, type, cmds, id, addr);
 393         if (sb)
 394                 drop_super(sb);
 395
 396         return ret;
 397 }
 398
 399 #if defined(CONFIG_COMPAT_FOR_U64_ALIGNMENT)
 400 /*
 401  * This code works only for 32 bit quota tools over 64 bit OS (x86_64, ia64)
 402  * and is necessary due to alignment problems.
 403  */
 404 struct compat_if_dqblk {
 405         compat_u64 dqb_bhardlimit;
 406         compat_u64 dqb_bsoftlimit;
 407         compat_u64 dqb_curspace;
 408         compat_u64 dqb_ihardlimit;
 409         compat_u64 dqb_isoftlimit;
 410         compat_u64 dqb_curinodes;
 411         compat_u64 dqb_btime;
 412         compat_u64 dqb_itime;
 413         compat_uint_t dqb_valid;
 414 };
 415
 416 /* XFS structures */
 417 struct compat_fs_qfilestat {
 418         compat_u64 dqb_bhardlimit;
 419         compat_u64 qfs_nblks;
 420         compat_uint_t qfs_nextents;
 421 };
 422
 423 struct compat_fs_quota_stat {
 424         __s8            qs_version;
 425         __u16           qs_flags;
 426         __s8            qs_pad;
 427         struct compat_fs_qfilestat      qs_uquota;
 428         struct compat_fs_qfilestat      qs_gquota;
 429         compat_uint_t   qs_incoredqs;
 430         compat_int_t    qs_btimelimit;
 431         compat_int_t    qs_itimelimit;
 432         compat_int_t    qs_rtbtimelimit;
 433         __u16           qs_bwarnlimit;
 434         __u16           qs_iwarnlimit;
 435 };
 436
 437 asmlinkage long sys32_quotactl(unsigned int cmd, const char __user *special,
 438                                                 qid_t id, void __user *addr)
 439 {
 440         unsigned int cmds;
 441         struct if_dqblk __user *dqblk;
 442         struct compat_if_dqblk __user *compat_dqblk;
 443         struct fs_quota_stat __user *fsqstat;
 444         struct compat_fs_quota_stat __user *compat_fsqstat;
 445         compat_uint_t data;
 446         u16 xdata;
 447         long ret;
 448
 449         cmds = cmd >> SUBCMDSHIFT;
 450
 451         switch (cmds) {
 452         case Q_GETQUOTA:
 453                 dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
 454                 compat_dqblk = addr;
 455                 ret = sys_quotactl(cmd, special, id, dqblk);
 456                 if (ret)
 457                         break;
 458                 if (copy_in_user(compat_dqblk, dqblk, sizeof(*compat_dqblk)) ||
 459                         get_user(data, &dqblk->dqb_valid) ||
 460                         put_user(data, &compat_dqblk->dqb_valid))
 461                         ret = -EFAULT;
 462                 break;
 463         case Q_SETQUOTA:
 464                 dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
 465                 compat_dqblk = addr;
 466                 ret = -EFAULT;
 467                 if (copy_in_user(dqblk, compat_dqblk, sizeof(*compat_dqblk)) ||
 468                         get_user(data, &compat_dqblk->dqb_valid) ||
 469                         put_user(data, &dqblk->dqb_valid))
 470                         break;
 471                 ret = sys_quotactl(cmd, special, id, dqblk);
 472                 break;
 473         case Q_XGETQSTAT:
 474                 fsqstat = compat_alloc_user_space(sizeof(struct fs_quota_stat));
 475                 compat_fsqstat = addr;
 476                 ret = sys_quotactl(cmd, special, id, fsqstat);
 477                 if (ret)
 478                         break;
 479                 ret = -EFAULT;
 480                 /* Copying qs_version, qs_flags, qs_pad */
 481                 if (copy_in_user(compat_fsqstat, fsqstat,
 482                         offsetof(struct compat_fs_quota_stat, qs_uquota)))
 483                         break;
 484                 /* Copying qs_uquota */
 485                 if (copy_in_user(&compat_fsqstat->qs_uquota,
 486                         &fsqstat->qs_uquota,
 487                         sizeof(compat_fsqstat->qs_uquota)) ||
 488                         get_user(data, &fsqstat->qs_uquota.qfs_nextents) ||
 489                         put_user(data, &compat_fsqstat->qs_uquota.qfs_nextents))
 490                         break;
 491                 /* Copying qs_gquota */
 492                 if (copy_in_user(&compat_fsqstat->qs_gquota,
 493                         &fsqstat->qs_gquota,
 494                         sizeof(compat_fsqstat->qs_gquota)) ||
 495                         get_user(data, &fsqstat->qs_gquota.qfs_nextents) ||
 496                         put_user(data, &compat_fsqstat->qs_gquota.qfs_nextents))
 497                         break;
 498                 /* Copying the rest */
 499                 if (copy_in_user(&compat_fsqstat->qs_incoredqs,
 500                         &fsqstat->qs_incoredqs,
 501                         sizeof(struct compat_fs_quota_stat) -
 502                         offsetof(struct compat_fs_quota_stat, qs_incoredqs)) ||
 503                         get_user(xdata, &fsqstat->qs_iwarnlimit) ||
 504                         put_user(xdata, &compat_fsqstat->qs_iwarnlimit))
 505                         break;
 506                 ret = 0;
 507                 break;
 508         default:
 509                 ret = sys_quotactl(cmd, special, id, addr);
 510         }
 511         return ret;
 512 }
 513 #endif