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/vs_context.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_QUOTAOFF:
  73                 case Q_SETINFO:
  74                 case Q_SETQUOTA:
  75                 case Q_GETQUOTA:
  76                         /* This is just informative test so we are satisfied without a lock */
  77                         if (!sb_has_quota_enabled(sb, type))
  78                                 return -ESRCH;
  79         }
  80
  81         /* Check privileges */
  82         if (cmd == Q_GETQUOTA) {
  83                 if (((type == USRQUOTA && current->euid != id) ||
  84                      (type == GRPQUOTA && !in_egroup_p(id))) &&
  85                     !vx_capable(CAP_SYS_ADMIN, VXC_QUOTA_CTL))
  86                         return -EPERM;
  87         }
  88         else if (cmd != Q_GETFMT && cmd != Q_SYNC && cmd != Q_GETINFO)
  89                 if (!vx_capable(CAP_SYS_ADMIN, VXC_QUOTA_CTL))
  90                         return -EPERM;
  91
  92         return 0;
  93 }
  94
  95 /* Check validity of XFS Quota Manager commands */
  96 static int xqm_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
  97 {
  98         if (type >= XQM_MAXQUOTAS)
  99                 return -EINVAL;
 100         if (!sb)
 101                 return -ENODEV;
 102         if (!sb->s_qcop)
 103                 return -ENOSYS;
 104
 105         switch (cmd) {
 106                 case Q_XQUOTAON:
 107                 case Q_XQUOTAOFF:
 108                 case Q_XQUOTARM:
 109                         if (!sb->s_qcop->set_xstate)
 110                                 return -ENOSYS;
 111                         break;
 112                 case Q_XGETQSTAT:
 113                         if (!sb->s_qcop->get_xstate)
 114                                 return -ENOSYS;
 115                         break;
 116                 case Q_XSETQLIM:
 117                         if (!sb->s_qcop->set_xquota)
 118                                 return -ENOSYS;
 119                         break;
 120                 case Q_XGETQUOTA:
 121                         if (!sb->s_qcop->get_xquota)
 122                                 return -ENOSYS;
 123                         break;
 124                 case Q_XQUOTASYNC:
 125                         if (!sb->s_qcop->quota_sync)
 126                                 return -ENOSYS;
 127                         break;
 128                 default:
 129                         return -EINVAL;
 130         }
 131
 132         /* Check privileges */
 133         if (cmd == Q_XGETQUOTA) {
 134                 if (((type == XQM_USRQUOTA && current->euid != id) ||
 135                      (type == XQM_GRPQUOTA && !in_egroup_p(id))) &&
 136                      !vx_capable(CAP_SYS_ADMIN, VXC_QUOTA_CTL))
 137                         return -EPERM;
 138         } else if (cmd != Q_XGETQSTAT && cmd != Q_XQUOTASYNC) {
 139                 if (!vx_capable(CAP_SYS_ADMIN, VXC_QUOTA_CTL))
 140                         return -EPERM;
 141         }
 142
 143         return 0;
 144 }
 145
 146 static int check_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
 147 {
 148         int error;
 149
 150         if (XQM_COMMAND(cmd))
 151                 error = xqm_quotactl_valid(sb, type, cmd, id);
 152         else
 153                 error = generic_quotactl_valid(sb, type, cmd, id);
 154         if (!error)
 155                 error = security_quotactl(cmd, type, id, sb);
 156         return error;
 157 }
 158
 159 static void quota_sync_sb(struct super_block *sb, int type)
 160 {
 161         int cnt;
 162         struct inode *discard[MAXQUOTAS];
 163
 164         sb->s_qcop->quota_sync(sb, type);
 165         /* This is not very clever (and fast) but currently I don't know about
 166          * any other simple way of getting quota data to disk and we must get
 167          * them there for userspace to be visible... */
 168         if (sb->s_op->sync_fs)
 169                 sb->s_op->sync_fs(sb, 1);
 170         sync_blockdev(sb->s_bdev);
 171
 172         /* Now when everything is written we can discard the pagecache so
 173          * that userspace sees the changes. We need i_mutex and so we could
 174          * not do it inside dqonoff_mutex. Moreover we need to be carefull
 175          * about races with quotaoff() (that is the reason why we have own
 176          * reference to inode). */
 177         mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
 178         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 179                 discard[cnt] = NULL;
 180                 if (type != -1 && cnt != type)
 181                         continue;
 182                 if (!sb_has_quota_enabled(sb, cnt))
 183                         continue;
 184                 discard[cnt] = igrab(sb_dqopt(sb)->files[cnt]);
 185         }
 186         mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
 187         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 188                 if (discard[cnt]) {
 189                         mutex_lock(&discard[cnt]->i_mutex);
 190                         truncate_inode_pages(&discard[cnt]->i_data, 0);
 191                         mutex_unlock(&discard[cnt]->i_mutex);
 192                         iput(discard[cnt]);
 193                 }
 194         }
 195 }
 196
 197 void sync_dquots(struct super_block *sb, int type)
 198 {
 199         int cnt, dirty;
 200
 201         if (sb) {
 202                 if (sb->s_qcop->quota_sync)
 203                         quota_sync_sb(sb, type);
 204                 return;
 205         }
 206
 207         spin_lock(&sb_lock);
 208 restart:
 209         list_for_each_entry(sb, &super_blocks, s_list) {
 210                 /* This test just improves performance so it needn't be reliable... */
 211                 for (cnt = 0, dirty = 0; cnt < MAXQUOTAS; cnt++)
 212                         if ((type == cnt || type == -1) && sb_has_quota_enabled(sb, cnt)
 213                             && info_any_dirty(&sb_dqopt(sb)->info[cnt]))
 214                                 dirty = 1;
 215                 if (!dirty)
 216                         continue;
 217                 sb->s_count++;
 218                 spin_unlock(&sb_lock);
 219                 down_read(&sb->s_umount);
 220                 if (sb->s_root && sb->s_qcop->quota_sync)
 221                         quota_sync_sb(sb, type);
 222                 up_read(&sb->s_umount);
 223                 spin_lock(&sb_lock);
 224                 if (__put_super_and_need_restart(sb))
 225                         goto restart;
 226         }
 227         spin_unlock(&sb_lock);
 228 }
 229
 230 /* Copy parameters and call proper function */
 231 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, void __user *addr)
 232 {
 233         int ret;
 234
 235         switch (cmd) {
 236                 case Q_QUOTAON: {
 237                         char *pathname;
 238
 239                         if (IS_ERR(pathname = getname(addr)))
 240                                 return PTR_ERR(pathname);
 241                         ret = sb->s_qcop->quota_on(sb, type, id, pathname);
 242                         putname(pathname);
 243                         return ret;
 244                 }
 245                 case Q_QUOTAOFF:
 246                         return sb->s_qcop->quota_off(sb, type);
 247
 248                 case Q_GETFMT: {
 249                         __u32 fmt;
 250
 251                         down_read(&sb_dqopt(sb)->dqptr_sem);
 252                         if (!sb_has_quota_enabled(sb, type)) {
 253                                 up_read(&sb_dqopt(sb)->dqptr_sem);
 254                                 return -ESRCH;
 255                         }
 256                         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
 257                         up_read(&sb_dqopt(sb)->dqptr_sem);
 258                         if (copy_to_user(addr, &fmt, sizeof(fmt)))
 259                                 return -EFAULT;
 260                         return 0;
 261                 }
 262                 case Q_GETINFO: {
 263                         struct if_dqinfo info;
 264
 265                         if ((ret = sb->s_qcop->get_info(sb, type, &info)))
 266                                 return ret;
 267                         if (copy_to_user(addr, &info, sizeof(info)))
 268                                 return -EFAULT;
 269                         return 0;
 270                 }
 271                 case Q_SETINFO: {
 272                         struct if_dqinfo info;
 273
 274                         if (copy_from_user(&info, addr, sizeof(info)))
 275                                 return -EFAULT;
 276                         return sb->s_qcop->set_info(sb, type, &info);
 277                 }
 278                 case Q_GETQUOTA: {
 279                         struct if_dqblk idq;
 280
 281                         if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)))
 282                                 return ret;
 283                         if (copy_to_user(addr, &idq, sizeof(idq)))
 284                                 return -EFAULT;
 285                         return 0;
 286                 }
 287                 case Q_SETQUOTA: {
 288                         struct if_dqblk idq;
 289
 290                         if (copy_from_user(&idq, addr, sizeof(idq)))
 291                                 return -EFAULT;
 292                         return sb->s_qcop->set_dqblk(sb, type, id, &idq);
 293                 }
 294                 case Q_SYNC:
 295                         sync_dquots(sb, type);
 296                         return 0;
 297
 298                 case Q_XQUOTAON:
 299                 case Q_XQUOTAOFF:
 300                 case Q_XQUOTARM: {
 301                         __u32 flags;
 302
 303                         if (copy_from_user(&flags, addr, sizeof(flags)))
 304                                 return -EFAULT;
 305                         return sb->s_qcop->set_xstate(sb, flags, cmd);
 306                 }
 307                 case Q_XGETQSTAT: {
 308                         struct fs_quota_stat fqs;
 309
 310                         if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
 311                                 return ret;
 312                         if (copy_to_user(addr, &fqs, sizeof(fqs)))
 313                                 return -EFAULT;
 314                         return 0;
 315                 }
 316                 case Q_XSETQLIM: {
 317                         struct fs_disk_quota fdq;
 318
 319                         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 320                                 return -EFAULT;
 321                        return sb->s_qcop->set_xquota(sb, type, id, &fdq);
 322                 }
 323                 case Q_XGETQUOTA: {
 324                         struct fs_disk_quota fdq;
 325
 326                         if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq)))
 327                                 return ret;
 328                         if (copy_to_user(addr, &fdq, sizeof(fdq)))
 329                                 return -EFAULT;
 330                         return 0;
 331                 }
 332                 case Q_XQUOTASYNC:
 333                         return sb->s_qcop->quota_sync(sb, type);
 334                 /* We never reach here unless validity check is broken */
 335                 default:
 336                         BUG();
 337         }
 338         return 0;
 339 }
 340
 341 #if defined(CONFIG_BLK_DEV_VROOT) || defined(CONFIG_BLK_DEV_VROOT_MODULE)
 342
 343 #include <linux/vroot.h>
 344 #include <linux/major.h>
 345 #include <linux/module.h>
 346 #include <linux/kallsyms.h>
 347 #include <linux/vserver/debug.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  * look up a superblock on which quota ops will be performed
 383  * - use the name of a block device to find the superblock thereon
 384  */
 385 static inline struct super_block *quotactl_block(const char __user *special)
 386 {
 387 #ifdef CONFIG_BLOCK
 388         struct block_device *bdev;
 389         struct super_block *sb;
 390         char *tmp = getname(special);
 391
 392         if (IS_ERR(tmp))
 393                 return ERR_PTR(PTR_ERR(tmp));
 394         bdev = lookup_bdev(tmp);
 395         putname(tmp);
 396         if (IS_ERR(bdev))
 397                 return ERR_PTR(PTR_ERR(bdev));
 398 #if defined(CONFIG_BLK_DEV_VROOT) || defined(CONFIG_BLK_DEV_VROOT_MODULE)
 399         if (bdev && bdev->bd_inode &&
 400                         imajor(bdev->bd_inode) == VROOT_MAJOR) {
 401                 struct block_device *bdnew = (void *)-EINVAL;
 402
 403                 if (vroot_get_real_bdev)
 404                         bdnew = vroot_get_real_bdev(bdev);
 405                 else
 406                         vxdprintk(VXD_CBIT(misc, 0),
 407                                         "vroot_get_real_bdev not set");
 408                 bdput(bdev);
 409                 if (IS_ERR(bdnew))
 410                         return ERR_PTR(PTR_ERR(bdnew));
 411                 bdev = bdnew;
 412         }
 413 #endif
 414         sb = get_super(bdev);
 415         bdput(bdev);
 416         if (!sb)
 417                 return ERR_PTR(-ENODEV);
 418
 419         return sb;
 420 #else
 421         return ERR_PTR(-ENODEV);
 422 #endif
 423 }
 424
 425 /*
 426  * This is the system call interface. This communicates with
 427  * the user-level programs. Currently this only supports diskquota
 428  * calls. Maybe we need to add the process quotas etc. in the future,
 429  * but we probably should use rlimits for that.
 430  */
 431 asmlinkage long sys_quotactl(unsigned int cmd, const char __user *special, qid_t id, void __user *addr)
 432 {
 433         uint cmds, type;
 434         struct super_block *sb = NULL;
 435         int ret;
 436
 437         cmds = cmd >> SUBCMDSHIFT;
 438         type = cmd & SUBCMDMASK;
 439
 440         if (cmds != Q_SYNC || special) {
 441                 sb = quotactl_block(special);
 442                 if (IS_ERR(sb))
 443                         return PTR_ERR(sb);
 444         }
 445
 446         ret = check_quotactl_valid(sb, type, cmds, id);
 447         if (ret >= 0)
 448                 ret = do_quotactl(sb, type, cmds, id, addr);
 449         if (sb)
 450                 drop_super(sb);
 451
 452         return ret;
 453 }