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/kernel.h>
  14 #include <linux/smp_lock.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/major.h>
  21 #include <linux/blkdev.h>
  22 #include <linux/vs_base.h>
  23 #include <linux/vserver/debug.h>
  24
  25 /* Check validity of generic quotactl commands */
  26 static int generic_quotactl_valid(struct super_block *sb, int type, int cmd, 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_QUOTAOFF:
  76                 case Q_SETINFO:
  77                 case Q_SETQUOTA:
  78                 case Q_GETQUOTA:
  79                         /* This is just informative test so we are satisfied without a lock */
  80                         if (!sb_has_quota_enabled(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                     !vx_capable(CAP_SYS_ADMIN, VXC_QUOTA_CTL))
  89                         return -EPERM;
  90         }
  91         else if (cmd != Q_GETFMT && cmd != Q_SYNC && cmd != Q_GETINFO)
  92                 if (!vx_capable(CAP_SYS_ADMIN, VXC_QUOTA_CTL))
  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, qid_t id)
 100 {
 101         if (type >= XQM_MAXQUOTAS)
 102                 return -EINVAL;
 103         if (!sb)
 104                 return -ENODEV;
 105         if (!sb->s_qcop)
 106                 return -ENOSYS;
 107
 108         switch (cmd) {
 109                 case Q_XQUOTAON:
 110                 case Q_XQUOTAOFF:
 111                 case Q_XQUOTARM:
 112                         if (!sb->s_qcop->set_xstate)
 113                                 return -ENOSYS;
 114                         break;
 115                 case Q_XGETQSTAT:
 116                         if (!sb->s_qcop->get_xstate)
 117                                 return -ENOSYS;
 118                         break;
 119                 case Q_XSETQLIM:
 120                         if (!sb->s_qcop->set_xquota)
 121                                 return -ENOSYS;
 122                         break;
 123                 case Q_XGETQUOTA:
 124                         if (!sb->s_qcop->get_xquota)
 125                                 return -ENOSYS;
 126                         break;
 127                 case Q_XQUOTASYNC:
 128                         if (!sb->s_qcop->quota_sync)
 129                                 return -ENOSYS;
 130                         break;
 131                 default:
 132                         return -EINVAL;
 133         }
 134
 135         /* Check privileges */
 136         if (cmd == Q_XGETQUOTA) {
 137                 if (((type == XQM_USRQUOTA && current->euid != id) ||
 138                      (type == XQM_GRPQUOTA && !in_egroup_p(id))) &&
 139                      !vx_capable(CAP_SYS_ADMIN, VXC_QUOTA_CTL))
 140                         return -EPERM;
 141         } else if (cmd != Q_XGETQSTAT && cmd != Q_XQUOTASYNC) {
 142                 if (!vx_capable(CAP_SYS_ADMIN, VXC_QUOTA_CTL))
 143                         return -EPERM;
 144         }
 145
 146         return 0;
 147 }
 148
 149 static int check_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
 150 {
 151         int error;
 152
 153         if (XQM_COMMAND(cmd))
 154                 error = xqm_quotactl_valid(sb, type, cmd, id);
 155         else
 156                 error = generic_quotactl_valid(sb, type, cmd, id);
 157         if (!error)
 158                 error = security_quotactl(cmd, type, id, sb);
 159         return error;
 160 }
 161
 162 static void quota_sync_sb(struct super_block *sb, int type)
 163 {
 164         int cnt;
 165         struct inode *discard[MAXQUOTAS];
 166
 167         sb->s_qcop->quota_sync(sb, type);
 168         /* This is not very clever (and fast) but currently I don't know about
 169          * any other simple way of getting quota data to disk and we must get
 170          * them there for userspace to be visible... */
 171         if (sb->s_op->sync_fs)
 172                 sb->s_op->sync_fs(sb, 1);
 173         sync_blockdev(sb->s_bdev);
 174
 175         /* Now when everything is written we can discard the pagecache so
 176          * that userspace sees the changes. We need i_mutex and so we could
 177          * not do it inside dqonoff_mutex. Moreover we need to be carefull
 178          * about races with quotaoff() (that is the reason why we have own
 179          * reference to inode). */
 180         mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
 181         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 182                 discard[cnt] = NULL;
 183                 if (type != -1 && cnt != type)
 184                         continue;
 185                 if (!sb_has_quota_enabled(sb, cnt))
 186                         continue;
 187                 discard[cnt] = igrab(sb_dqopt(sb)->files[cnt]);
 188         }
 189         mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
 190         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 191                 if (discard[cnt]) {
 192                         mutex_lock(&discard[cnt]->i_mutex);
 193                         truncate_inode_pages(&discard[cnt]->i_data, 0);
 194                         mutex_unlock(&discard[cnt]->i_mutex);
 195                         iput(discard[cnt]);
 196                 }
 197         }
 198 }
 199
 200 void sync_dquots(struct super_block *sb, int type)
 201 {
 202         int cnt, dirty;
 203
 204         if (sb) {
 205                 if (sb->s_qcop->quota_sync)
 206                         quota_sync_sb(sb, type);
 207                 return;
 208         }
 209
 210         spin_lock(&sb_lock);
 211 restart:
 212         list_for_each_entry(sb, &super_blocks, s_list) {
 213                 /* This test just improves performance so it needn't be reliable... */
 214                 for (cnt = 0, dirty = 0; cnt < MAXQUOTAS; cnt++)
 215                         if ((type == cnt || type == -1) && sb_has_quota_enabled(sb, cnt)
 216                             && info_any_dirty(&sb_dqopt(sb)->info[cnt]))
 217                                 dirty = 1;
 218                 if (!dirty)
 219                         continue;
 220                 sb->s_count++;
 221                 spin_unlock(&sb_lock);
 222                 down_read(&sb->s_umount);
 223                 if (sb->s_root && sb->s_qcop->quota_sync)
 224                         quota_sync_sb(sb, type);
 225                 up_read(&sb->s_umount);
 226                 spin_lock(&sb_lock);
 227                 if (__put_super_and_need_restart(sb))
 228                         goto restart;
 229         }
 230         spin_unlock(&sb_lock);
 231 }
 232
 233 /* Copy parameters and call proper function */
 234 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, void __user *addr)
 235 {
 236         int ret;
 237
 238         switch (cmd) {
 239                 case Q_QUOTAON: {
 240                         char *pathname;
 241
 242                         if (IS_ERR(pathname = getname(addr)))
 243                                 return PTR_ERR(pathname);
 244                         ret = sb->s_qcop->quota_on(sb, type, id, pathname);
 245                         putname(pathname);
 246                         return ret;
 247                 }
 248                 case Q_QUOTAOFF:
 249                         return sb->s_qcop->quota_off(sb, type);
 250
 251                 case Q_GETFMT: {
 252                         __u32 fmt;
 253
 254                         down_read(&sb_dqopt(sb)->dqptr_sem);
 255                         if (!sb_has_quota_enabled(sb, type)) {
 256                                 up_read(&sb_dqopt(sb)->dqptr_sem);
 257                                 return -ESRCH;
 258                         }
 259                         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
 260                         up_read(&sb_dqopt(sb)->dqptr_sem);
 261                         if (copy_to_user(addr, &fmt, sizeof(fmt)))
 262                                 return -EFAULT;
 263                         return 0;
 264                 }
 265                 case Q_GETINFO: {
 266                         struct if_dqinfo info;
 267
 268                         if ((ret = sb->s_qcop->get_info(sb, type, &info)))
 269                                 return ret;
 270                         if (copy_to_user(addr, &info, sizeof(info)))
 271                                 return -EFAULT;
 272                         return 0;
 273                 }
 274                 case Q_SETINFO: {
 275                         struct if_dqinfo info;
 276
 277                         if (copy_from_user(&info, addr, sizeof(info)))
 278                                 return -EFAULT;
 279                         return sb->s_qcop->set_info(sb, type, &info);
 280                 }
 281                 case Q_GETQUOTA: {
 282                         struct if_dqblk idq;
 283
 284                         if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)))
 285                                 return ret;
 286                         if (copy_to_user(addr, &idq, sizeof(idq)))
 287                                 return -EFAULT;
 288                         return 0;
 289                 }
 290                 case Q_SETQUOTA: {
 291                         struct if_dqblk idq;
 292
 293                         if (copy_from_user(&idq, addr, sizeof(idq)))
 294                                 return -EFAULT;
 295                         return sb->s_qcop->set_dqblk(sb, type, id, &idq);
 296                 }
 297                 case Q_SYNC:
 298                         sync_dquots(sb, type);
 299                         return 0;
 300
 301                 case Q_XQUOTAON:
 302                 case Q_XQUOTAOFF:
 303                 case Q_XQUOTARM: {
 304                         __u32 flags;
 305
 306                         if (copy_from_user(&flags, addr, sizeof(flags)))
 307                                 return -EFAULT;
 308                         return sb->s_qcop->set_xstate(sb, flags, cmd);
 309                 }
 310                 case Q_XGETQSTAT: {
 311                         struct fs_quota_stat fqs;
 312
 313                         if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
 314                                 return ret;
 315                         if (copy_to_user(addr, &fqs, sizeof(fqs)))
 316                                 return -EFAULT;
 317                         return 0;
 318                 }
 319                 case Q_XSETQLIM: {
 320                         struct fs_disk_quota fdq;
 321
 322                         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 323                                 return -EFAULT;
 324                        return sb->s_qcop->set_xquota(sb, type, id, &fdq);
 325                 }
 326                 case Q_XGETQUOTA: {
 327                         struct fs_disk_quota fdq;
 328
 329                         if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq)))
 330                                 return ret;
 331                         if (copy_to_user(addr, &fdq, sizeof(fdq)))
 332                                 return -EFAULT;
 333                         return 0;
 334                 }
 335                 case Q_XQUOTASYNC:
 336                         return sb->s_qcop->quota_sync(sb, type);
 337                 /* We never reach here unless validity check is broken */
 338                 default:
 339                         BUG();
 340         }
 341         return 0;
 342 }
 343
 344 #if defined(CONFIG_BLK_DEV_VROOT) || defined(CONFIG_BLK_DEV_VROOT_MODULE)
 345
 346 #include <linux/vroot.h>
 347 #include <linux/kallsyms.h>
 348
 349 static vroot_grb_func *vroot_get_real_bdev = NULL;
 350
 351 static spinlock_t vroot_grb_lock = SPIN_LOCK_UNLOCKED;
 352
 353 int register_vroot_grb(vroot_grb_func *func) {
 354         int ret = -EBUSY;
 355
 356         spin_lock(&vroot_grb_lock);
 357         if (!vroot_get_real_bdev) {
 358                 vroot_get_real_bdev = func;
 359                 ret = 0;
 360         }
 361         spin_unlock(&vroot_grb_lock);
 362         return ret;
 363 }
 364 EXPORT_SYMBOL(register_vroot_grb);
 365
 366 int unregister_vroot_grb(vroot_grb_func *func) {
 367         int ret = -EINVAL;
 368
 369         spin_lock(&vroot_grb_lock);
 370         if (vroot_get_real_bdev) {
 371                 vroot_get_real_bdev = NULL;
 372                 ret = 0;
 373         }
 374         spin_unlock(&vroot_grb_lock);
 375         return ret;
 376 }
 377 EXPORT_SYMBOL(unregister_vroot_grb);
 378
 379 #endif
 380
 381 /*
 382  * This is the system call interface. This communicates with
 383  * the user-level programs. Currently this only supports diskquota
 384  * calls. Maybe we need to add the process quotas etc. in the future,
 385  * but we probably should use rlimits for that.
 386  */
 387 asmlinkage long sys_quotactl(unsigned int cmd, const char __user *special, qid_t id, void __user *addr)
 388 {
 389         uint cmds, type;
 390         struct super_block *sb = NULL;
 391         struct block_device *bdev;
 392         char *tmp;
 393         int ret;
 394
 395         cmds = cmd >> SUBCMDSHIFT;
 396         type = cmd & SUBCMDMASK;
 397
 398         if (cmds != Q_SYNC || special) {
 399                 tmp = getname(special);
 400                 if (IS_ERR(tmp))
 401                         return PTR_ERR(tmp);
 402                 bdev = lookup_bdev(tmp);
 403                 putname(tmp);
 404                 if (IS_ERR(bdev))
 405                         return PTR_ERR(bdev);
 406 #if defined(CONFIG_BLK_DEV_VROOT) || defined(CONFIG_BLK_DEV_VROOT_MODULE)
 407                 if (bdev && bdev->bd_inode &&
 408                         imajor(bdev->bd_inode) == VROOT_MAJOR) {
 409                         struct block_device *bdnew = (void *)-EINVAL;
 410
 411                         if (vroot_get_real_bdev)
 412                                 bdnew = vroot_get_real_bdev(bdev);
 413                         else
 414                                 vxdprintk(VXD_CBIT(misc, 0),
 415                                         "vroot_get_real_bdev not set");
 416
 417                         bdput(bdev);
 418                         if (IS_ERR(bdnew))
 419                                 return PTR_ERR(bdnew);
 420                         bdev = bdnew;
 421                 }
 422 #endif
 423                 sb = get_super(bdev);
 424                 bdput(bdev);
 425                 if (!sb)
 426                         return -ENODEV;
 427         }
 428
 429         ret = check_quotactl_valid(sb, type, cmds, id);
 430         if (ret >= 0)
 431                 ret = do_quotactl(sb, type, cmds, id, addr);
 432         if (sb)
 433                 drop_super(sb);
 434
 435         return ret;
 436 }