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/vserver/debug.h>
  23
  24 /* Check validity of generic quotactl commands */
  25 static int generic_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
  26 {
  27         if (type >= MAXQUOTAS)
  28                 return -EINVAL;
  29         if (!sb && cmd != Q_SYNC)
  30                 return -ENODEV;
  31         /* Is operation supported? */
  32         if (sb && !sb->s_qcop)
  33                 return -ENOSYS;
  34
  35         switch (cmd) {
  36                 case Q_GETFMT:
  37                         break;
  38                 case Q_QUOTAON:
  39                         if (!sb->s_qcop->quota_on)
  40                                 return -ENOSYS;
  41                         break;
  42                 case Q_QUOTAOFF:
  43                         if (!sb->s_qcop->quota_off)
  44                                 return -ENOSYS;
  45                         break;
  46                 case Q_SETINFO:
  47                         if (!sb->s_qcop->set_info)
  48                                 return -ENOSYS;
  49                         break;
  50                 case Q_GETINFO:
  51                         if (!sb->s_qcop->get_info)
  52                                 return -ENOSYS;
  53                         break;
  54                 case Q_SETQUOTA:
  55                         if (!sb->s_qcop->set_dqblk)
  56                                 return -ENOSYS;
  57                         break;
  58                 case Q_GETQUOTA:
  59                         if (!sb->s_qcop->get_dqblk)
  60                                 return -ENOSYS;
  61                         break;
  62                 case Q_SYNC:
  63                         if (sb && !sb->s_qcop->quota_sync)
  64                                 return -ENOSYS;
  65                         break;
  66                 default:
  67                         return -EINVAL;
  68         }
  69
  70         /* Is quota turned on for commands which need it? */
  71         switch (cmd) {
  72                 case Q_GETFMT:
  73                 case Q_GETINFO:
  74                 case Q_QUOTAOFF:
  75                 case Q_SETINFO:
  76                 case Q_SETQUOTA:
  77                 case Q_GETQUOTA:
  78                         /* This is just informative test so we are satisfied without a lock */
  79                         if (!sb_has_quota_enabled(sb, type))
  80                                 return -ESRCH;
  81         }
  82
  83         /* Check privileges */
  84         if (cmd == Q_GETQUOTA) {
  85                 if (((type == USRQUOTA && current->euid != id) ||
  86                      (type == GRPQUOTA && !in_egroup_p(id))) &&
  87                     !vx_capable(CAP_SYS_ADMIN, VXC_QUOTA_CTL))
  88                         return -EPERM;
  89         }
  90         else if (cmd != Q_GETFMT && cmd != Q_SYNC && cmd != Q_GETINFO)
  91                 if (!vx_capable(CAP_SYS_ADMIN, VXC_QUOTA_CTL))
  92                         return -EPERM;
  93
  94         return 0;
  95 }
  96
  97 /* Check validity of XFS Quota Manager commands */
  98 static int xqm_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
  99 {
 100         if (type >= XQM_MAXQUOTAS)
 101                 return -EINVAL;
 102         if (!sb)
 103                 return -ENODEV;
 104         if (!sb->s_qcop)
 105                 return -ENOSYS;
 106
 107         switch (cmd) {
 108                 case Q_XQUOTAON:
 109                 case Q_XQUOTAOFF:
 110                 case Q_XQUOTARM:
 111                         if (!sb->s_qcop->set_xstate)
 112                                 return -ENOSYS;
 113                         break;
 114                 case Q_XGETQSTAT:
 115                         if (!sb->s_qcop->get_xstate)
 116                                 return -ENOSYS;
 117                         break;
 118                 case Q_XSETQLIM:
 119                         if (!sb->s_qcop->set_xquota)
 120                                 return -ENOSYS;
 121                         break;
 122                 case Q_XGETQUOTA:
 123                         if (!sb->s_qcop->get_xquota)
 124                                 return -ENOSYS;
 125                         break;
 126                 case Q_XQUOTASYNC:
 127                         if (!sb->s_qcop->quota_sync)
 128                                 return -ENOSYS;
 129                         break;
 130                 default:
 131                         return -EINVAL;
 132         }
 133
 134         /* Check privileges */
 135         if (cmd == Q_XGETQUOTA) {
 136                 if (((type == XQM_USRQUOTA && current->euid != id) ||
 137                      (type == XQM_GRPQUOTA && !in_egroup_p(id))) &&
 138                      !vx_capable(CAP_SYS_ADMIN, VXC_QUOTA_CTL))
 139                         return -EPERM;
 140         } else if (cmd != Q_XGETQSTAT && cmd != Q_XQUOTASYNC) {
 141                 if (!vx_capable(CAP_SYS_ADMIN, VXC_QUOTA_CTL))
 142                         return -EPERM;
 143         }
 144
 145         return 0;
 146 }
 147
 148 static int check_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
 149 {
 150         int error;
 151
 152         if (XQM_COMMAND(cmd))
 153                 error = xqm_quotactl_valid(sb, type, cmd, id);
 154         else
 155                 error = generic_quotactl_valid(sb, type, cmd, id);
 156         if (!error)
 157                 error = security_quotactl(cmd, type, id, sb);
 158         return error;
 159 }
 160
 161 static void quota_sync_sb(struct super_block *sb, int type)
 162 {
 163         int cnt;
 164         struct inode *discard[MAXQUOTAS];
 165
 166         sb->s_qcop->quota_sync(sb, type);
 167         /* This is not very clever (and fast) but currently I don't know about
 168          * any other simple way of getting quota data to disk and we must get
 169          * them there for userspace to be visible... */
 170         if (sb->s_op->sync_fs)
 171                 sb->s_op->sync_fs(sb, 1);
 172         sync_blockdev(sb->s_bdev);
 173
 174         /* Now when everything is written we can discard the pagecache so
 175          * that userspace sees the changes. We need i_mutex and so we could
 176          * not do it inside dqonoff_mutex. Moreover we need to be carefull
 177          * about races with quotaoff() (that is the reason why we have own
 178          * reference to inode). */
 179         mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
 180         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 181                 discard[cnt] = NULL;
 182                 if (type != -1 && cnt != type)
 183                         continue;
 184                 if (!sb_has_quota_enabled(sb, cnt))
 185                         continue;
 186                 discard[cnt] = igrab(sb_dqopt(sb)->files[cnt]);
 187         }
 188         mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
 189         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 190                 if (discard[cnt]) {
 191                         mutex_lock(&discard[cnt]->i_mutex);
 192                         truncate_inode_pages(&discard[cnt]->i_data, 0);
 193                         mutex_unlock(&discard[cnt]->i_mutex);
 194                         iput(discard[cnt]);
 195                 }
 196         }
 197 }
 198
 199 void sync_dquots(struct super_block *sb, int type)
 200 {
 201         int cnt, dirty;
 202
 203         if (sb) {
 204                 if (sb->s_qcop->quota_sync)
 205                         quota_sync_sb(sb, type);
 206                 return;
 207         }
 208
 209         spin_lock(&sb_lock);
 210 restart:
 211         list_for_each_entry(sb, &super_blocks, s_list) {
 212                 /* This test just improves performance so it needn't be reliable... */
 213                 for (cnt = 0, dirty = 0; cnt < MAXQUOTAS; cnt++)
 214                         if ((type == cnt || type == -1) && sb_has_quota_enabled(sb, cnt)
 215                             && info_any_dirty(&sb_dqopt(sb)->info[cnt]))
 216                                 dirty = 1;
 217                 if (!dirty)
 218                         continue;
 219                 sb->s_count++;
 220                 spin_unlock(&sb_lock);
 221                 down_read(&sb->s_umount);
 222                 if (sb->s_root && sb->s_qcop->quota_sync)
 223                         quota_sync_sb(sb, type);
 224                 up_read(&sb->s_umount);
 225                 spin_lock(&sb_lock);
 226                 if (__put_super_and_need_restart(sb))
 227                         goto restart;
 228         }
 229         spin_unlock(&sb_lock);
 230 }
 231
 232 /* Copy parameters and call proper function */
 233 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, void __user *addr)
 234 {
 235         int ret;
 236
 237         switch (cmd) {
 238                 case Q_QUOTAON: {
 239                         char *pathname;
 240
 241                         if (IS_ERR(pathname = getname(addr)))
 242                                 return PTR_ERR(pathname);
 243                         ret = sb->s_qcop->quota_on(sb, type, id, pathname);
 244                         putname(pathname);
 245                         return ret;
 246                 }
 247                 case Q_QUOTAOFF:
 248                         return sb->s_qcop->quota_off(sb, type);
 249
 250                 case Q_GETFMT: {
 251                         __u32 fmt;
 252
 253                         down_read(&sb_dqopt(sb)->dqptr_sem);
 254                         if (!sb_has_quota_enabled(sb, type)) {
 255                                 up_read(&sb_dqopt(sb)->dqptr_sem);
 256                                 return -ESRCH;
 257                         }
 258                         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
 259                         up_read(&sb_dqopt(sb)->dqptr_sem);
 260                         if (copy_to_user(addr, &fmt, sizeof(fmt)))
 261                                 return -EFAULT;
 262                         return 0;
 263                 }
 264                 case Q_GETINFO: {
 265                         struct if_dqinfo info;
 266
 267                         if ((ret = sb->s_qcop->get_info(sb, type, &info)))
 268                                 return ret;
 269                         if (copy_to_user(addr, &info, sizeof(info)))
 270                                 return -EFAULT;
 271                         return 0;
 272                 }
 273                 case Q_SETINFO: {
 274                         struct if_dqinfo info;
 275
 276                         if (copy_from_user(&info, addr, sizeof(info)))
 277                                 return -EFAULT;
 278                         return sb->s_qcop->set_info(sb, type, &info);
 279                 }
 280                 case Q_GETQUOTA: {
 281                         struct if_dqblk idq;
 282
 283                         if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)))
 284                                 return ret;
 285                         if (copy_to_user(addr, &idq, sizeof(idq)))
 286                                 return -EFAULT;
 287                         return 0;
 288                 }
 289                 case Q_SETQUOTA: {
 290                         struct if_dqblk idq;
 291
 292                         if (copy_from_user(&idq, addr, sizeof(idq)))
 293                                 return -EFAULT;
 294                         return sb->s_qcop->set_dqblk(sb, type, id, &idq);
 295                 }
 296                 case Q_SYNC:
 297                         sync_dquots(sb, type);
 298                         return 0;
 299
 300                 case Q_XQUOTAON:
 301                 case Q_XQUOTAOFF:
 302                 case Q_XQUOTARM: {
 303                         __u32 flags;
 304
 305                         if (copy_from_user(&flags, addr, sizeof(flags)))
 306                                 return -EFAULT;
 307                         return sb->s_qcop->set_xstate(sb, flags, cmd);
 308                 }
 309                 case Q_XGETQSTAT: {
 310                         struct fs_quota_stat fqs;
 311
 312                         if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
 313                                 return ret;
 314                         if (copy_to_user(addr, &fqs, sizeof(fqs)))
 315                                 return -EFAULT;
 316                         return 0;
 317                 }
 318                 case Q_XSETQLIM: {
 319                         struct fs_disk_quota fdq;
 320
 321                         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 322                                 return -EFAULT;
 323                        return sb->s_qcop->set_xquota(sb, type, id, &fdq);
 324                 }
 325                 case Q_XGETQUOTA: {
 326                         struct fs_disk_quota fdq;
 327
 328                         if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq)))
 329                                 return ret;
 330                         if (copy_to_user(addr, &fdq, sizeof(fdq)))
 331                                 return -EFAULT;
 332                         return 0;
 333                 }
 334                 case Q_XQUOTASYNC:
 335                         return sb->s_qcop->quota_sync(sb, type);
 336                 /* We never reach here unless validity check is broken */
 337                 default:
 338                         BUG();
 339         }
 340         return 0;
 341 }
 342
 343 #if defined(CONFIG_BLK_DEV_VROOT) || defined(CONFIG_BLK_DEV_VROOT_MODULE)
 344
 345 #include <linux/vroot.h>
 346 #include <linux/kallsyms.h>
 347
 348 static vroot_grb_func *vroot_get_real_bdev = NULL;
 349
 350 static spinlock_t vroot_grb_lock = SPIN_LOCK_UNLOCKED;
 351
 352 int register_vroot_grb(vroot_grb_func *func) {
 353         int ret = -EBUSY;
 354
 355         spin_lock(&vroot_grb_lock);
 356         if (!vroot_get_real_bdev) {
 357                 vroot_get_real_bdev = func;
 358                 ret = 0;
 359         }
 360         spin_unlock(&vroot_grb_lock);
 361         return ret;
 362 }
 363 EXPORT_SYMBOL(register_vroot_grb);
 364
 365 int unregister_vroot_grb(vroot_grb_func *func) {
 366         int ret = -EINVAL;
 367
 368         spin_lock(&vroot_grb_lock);
 369         if (vroot_get_real_bdev) {
 370                 vroot_get_real_bdev = NULL;
 371                 ret = 0;
 372         }
 373         spin_unlock(&vroot_grb_lock);
 374         return ret;
 375 }
 376 EXPORT_SYMBOL(unregister_vroot_grb);
 377
 378 #endif
 379
 380 /*
 381  * This is the system call interface. This communicates with
 382  * the user-level programs. Currently this only supports diskquota
 383  * calls. Maybe we need to add the process quotas etc. in the future,
 384  * but we probably should use rlimits for that.
 385  */
 386 asmlinkage long sys_quotactl(unsigned int cmd, const char __user *special, qid_t id, void __user *addr)
 387 {
 388         uint cmds, type;
 389         struct super_block *sb = NULL;
 390         struct block_device *bdev;
 391         char *tmp;
 392         int ret;
 393
 394         cmds = cmd >> SUBCMDSHIFT;
 395         type = cmd & SUBCMDMASK;
 396
 397         if (cmds != Q_SYNC || special) {
 398                 tmp = getname(special);
 399                 if (IS_ERR(tmp))
 400                         return PTR_ERR(tmp);
 401                 bdev = lookup_bdev(tmp);
 402                 putname(tmp);
 403                 if (IS_ERR(bdev))
 404                         return PTR_ERR(bdev);
 405 #if defined(CONFIG_BLK_DEV_VROOT) || defined(CONFIG_BLK_DEV_VROOT_MODULE)
 406                 if (bdev && bdev->bd_inode &&
 407                         imajor(bdev->bd_inode) == VROOT_MAJOR) {
 408                         struct block_device *bdnew = (void *)-EINVAL;
 409
 410                         if (vroot_get_real_bdev)
 411                                 bdnew = vroot_get_real_bdev(bdev);
 412                         else
 413                                 vxdprintk(VXD_CBIT(misc, 0),
 414                                         "vroot_get_real_bdev not set");
 415
 416                         bdput(bdev);
 417                         if (IS_ERR(bdnew))
 418                                 return PTR_ERR(bdnew);
 419                         bdev = bdnew;
 420                 }
 421 #endif
 422                 sb = get_super(bdev);
 423                 bdput(bdev);
 424                 if (!sb)
 425                         return -ENODEV;
 426         }
 427
 428         ret = check_quotactl_valid(sb, type, cmds, id);
 429         if (ret >= 0)
 430                 ret = do_quotactl(sb, type, cmds, id, addr);
 431         if (sb)
 432                 drop_super(sb);
 433
 434         return ret;
 435 }