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/major.h>
  19 #include <linux/blkdev.h>
  20
  21 /* Check validity of generic quotactl commands */
  22 static int generic_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
  23 {
  24         if (type >= MAXQUOTAS)
  25                 return -EINVAL;
  26         if (!sb && cmd != Q_SYNC)
  27                 return -ENODEV;
  28         /* Is operation supported? */
  29         if (sb && !sb->s_qcop)
  30                 return -ENOSYS;
  31
  32         switch (cmd) {
  33                 case Q_GETFMT:
  34                         break;
  35                 case Q_QUOTAON:
  36                         if (!sb->s_qcop->quota_on)
  37                                 return -ENOSYS;
  38                         break;
  39                 case Q_QUOTAOFF:
  40                         if (!sb->s_qcop->quota_off)
  41                                 return -ENOSYS;
  42                         break;
  43                 case Q_SETINFO:
  44                         if (!sb->s_qcop->set_info)
  45                                 return -ENOSYS;
  46                         break;
  47                 case Q_GETINFO:
  48                         if (!sb->s_qcop->get_info)
  49                                 return -ENOSYS;
  50                         break;
  51                 case Q_SETQUOTA:
  52                         if (!sb->s_qcop->set_dqblk)
  53                                 return -ENOSYS;
  54                         break;
  55                 case Q_GETQUOTA:
  56                         if (!sb->s_qcop->get_dqblk)
  57                                 return -ENOSYS;
  58                         break;
  59                 case Q_SYNC:
  60                         if (sb && !sb->s_qcop->quota_sync)
  61                                 return -ENOSYS;
  62                         break;
  63                 default:
  64                         return -EINVAL;
  65         }
  66
  67         /* Is quota turned on for commands which need it? */
  68         switch (cmd) {
  69                 case Q_GETFMT:
  70                 case Q_GETINFO:
  71                 case Q_QUOTAOFF:
  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) && !vx_ccaps(VXC_QUOTA_CTL))
  85                         return -EPERM;
  86         }
  87         else if (cmd != Q_GETFMT && cmd != Q_SYNC && cmd != Q_GETINFO)
  88                 if (!capable(CAP_SYS_ADMIN) && !vx_ccaps(VXC_QUOTA_CTL))
  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                 default:
 124                         return -EINVAL;
 125         }
 126
 127         /* Check privileges */
 128         if (cmd == Q_XGETQUOTA) {
 129                 if (((type == XQM_USRQUOTA && current->euid != id) ||
 130                      (type == XQM_GRPQUOTA && !in_egroup_p(id))) &&
 131                      !capable(CAP_SYS_ADMIN) && !vx_ccaps(VXC_QUOTA_CTL))
 132                         return -EPERM;
 133         } else if (cmd != Q_XGETQSTAT) {
 134                 if (!capable(CAP_SYS_ADMIN) && !vx_ccaps(VXC_QUOTA_CTL))
 135                         return -EPERM;
 136         }
 137
 138         return 0;
 139 }
 140
 141 static int check_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
 142 {
 143         int error;
 144
 145         if (XQM_COMMAND(cmd))
 146                 error = xqm_quotactl_valid(sb, type, cmd, id);
 147         else
 148                 error = generic_quotactl_valid(sb, type, cmd, id);
 149         if (!error)
 150                 error = security_quotactl(cmd, type, id, sb);
 151         return error;
 152 }
 153
 154 static struct super_block *get_super_to_sync(int type)
 155 {
 156         struct list_head *head;
 157         int cnt, dirty;
 158
 159 restart:
 160         spin_lock(&sb_lock);
 161         list_for_each(head, &super_blocks) {
 162                 struct super_block *sb = list_entry(head, struct super_block, s_list);
 163
 164                 /* This test just improves performance so it needn't be reliable... */
 165                 for (cnt = 0, dirty = 0; cnt < MAXQUOTAS; cnt++)
 166                         if ((type == cnt || type == -1) && sb_has_quota_enabled(sb, cnt)
 167                             && info_any_dirty(&sb_dqopt(sb)->info[cnt]))
 168                                 dirty = 1;
 169                 if (!dirty)
 170                         continue;
 171                 sb->s_count++;
 172                 spin_unlock(&sb_lock);
 173                 down_read(&sb->s_umount);
 174                 if (!sb->s_root) {
 175                         drop_super(sb);
 176                         goto restart;
 177                 }
 178                 return sb;
 179         }
 180         spin_unlock(&sb_lock);
 181         return NULL;
 182 }
 183
 184 static void quota_sync_sb(struct super_block *sb, int type)
 185 {
 186         int cnt;
 187         struct inode *discard[MAXQUOTAS];
 188
 189         sb->s_qcop->quota_sync(sb, type);
 190         /* This is not very clever (and fast) but currently I don't know about
 191          * any other simple way of getting quota data to disk and we must get
 192          * them there for userspace to be visible... */
 193         if (sb->s_op->sync_fs)
 194                 sb->s_op->sync_fs(sb, 1);
 195         sync_blockdev(sb->s_bdev);
 196
 197         /* Now when everything is written we can discard the pagecache so
 198          * that userspace sees the changes. We need i_sem and so we could
 199          * not do it inside dqonoff_sem. Moreover we need to be carefull
 200          * about races with quotaoff() (that is the reason why we have own
 201          * reference to inode). */
 202         down(&sb_dqopt(sb)->dqonoff_sem);
 203         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 204                 discard[cnt] = NULL;
 205                 if (type != -1 && cnt != type)
 206                         continue;
 207                 if (!sb_has_quota_enabled(sb, cnt))
 208                         continue;
 209                 discard[cnt] = igrab(sb_dqopt(sb)->files[cnt]);
 210         }
 211         up(&sb_dqopt(sb)->dqonoff_sem);
 212         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 213                 if (discard[cnt]) {
 214                         down(&discard[cnt]->i_sem);
 215                         truncate_inode_pages(&discard[cnt]->i_data, 0);
 216                         up(&discard[cnt]->i_sem);
 217                         iput(discard[cnt]);
 218                 }
 219         }
 220 }
 221
 222 void sync_dquots(struct super_block *sb, int type)
 223 {
 224         if (sb) {
 225                 if (sb->s_qcop->quota_sync)
 226                         quota_sync_sb(sb, type);
 227         }
 228         else {
 229                 while ((sb = get_super_to_sync(type)) != NULL) {
 230                         if (sb->s_qcop->quota_sync)
 231                                 quota_sync_sb(sb, type);
 232                         drop_super(sb);
 233                 }
 234         }
 235 }
 236
 237 /* Copy parameters and call proper function */
 238 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, void __user *addr)
 239 {
 240         int ret;
 241
 242         switch (cmd) {
 243                 case Q_QUOTAON: {
 244                         char *pathname;
 245
 246                         if (IS_ERR(pathname = getname(addr)))
 247                                 return PTR_ERR(pathname);
 248                         ret = sb->s_qcop->quota_on(sb, type, id, pathname);
 249                         putname(pathname);
 250                         return ret;
 251                 }
 252                 case Q_QUOTAOFF:
 253                         return sb->s_qcop->quota_off(sb, type);
 254
 255                 case Q_GETFMT: {
 256                         __u32 fmt;
 257
 258                         down_read(&sb_dqopt(sb)->dqptr_sem);
 259                         if (!sb_has_quota_enabled(sb, type)) {
 260                                 up_read(&sb_dqopt(sb)->dqptr_sem);
 261                                 return -ESRCH;
 262                         }
 263                         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
 264                         up_read(&sb_dqopt(sb)->dqptr_sem);
 265                         if (copy_to_user(addr, &fmt, sizeof(fmt)))
 266                                 return -EFAULT;
 267                         return 0;
 268                 }
 269                 case Q_GETINFO: {
 270                         struct if_dqinfo info;
 271
 272                         if ((ret = sb->s_qcop->get_info(sb, type, &info)))
 273                                 return ret;
 274                         if (copy_to_user(addr, &info, sizeof(info)))
 275                                 return -EFAULT;
 276                         return 0;
 277                 }
 278                 case Q_SETINFO: {
 279                         struct if_dqinfo info;
 280
 281                         if (copy_from_user(&info, addr, sizeof(info)))
 282                                 return -EFAULT;
 283                         return sb->s_qcop->set_info(sb, type, &info);
 284                 }
 285                 case Q_GETQUOTA: {
 286                         struct if_dqblk idq;
 287
 288                         if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)))
 289                                 return ret;
 290                         if (copy_to_user(addr, &idq, sizeof(idq)))
 291                                 return -EFAULT;
 292                         return 0;
 293                 }
 294                 case Q_SETQUOTA: {
 295                         struct if_dqblk idq;
 296
 297                         if (copy_from_user(&idq, addr, sizeof(idq)))
 298                                 return -EFAULT;
 299                         return sb->s_qcop->set_dqblk(sb, type, id, &idq);
 300                 }
 301                 case Q_SYNC:
 302                         sync_dquots(sb, type);
 303                         return 0;
 304
 305                 case Q_XQUOTAON:
 306                 case Q_XQUOTAOFF:
 307                 case Q_XQUOTARM: {
 308                         __u32 flags;
 309
 310                         if (copy_from_user(&flags, addr, sizeof(flags)))
 311                                 return -EFAULT;
 312                         return sb->s_qcop->set_xstate(sb, flags, cmd);
 313                 }
 314                 case Q_XGETQSTAT: {
 315                         struct fs_quota_stat fqs;
 316
 317                         if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
 318                                 return ret;
 319                         if (copy_to_user(addr, &fqs, sizeof(fqs)))
 320                                 return -EFAULT;
 321                         return 0;
 322                 }
 323                 case Q_XSETQLIM: {
 324                         struct fs_disk_quota fdq;
 325
 326                         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 327                                 return -EFAULT;
 328                        return sb->s_qcop->set_xquota(sb, type, id, &fdq);
 329                 }
 330                 case Q_XGETQUOTA: {
 331                         struct fs_disk_quota fdq;
 332
 333                         if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq)))
 334                                 return ret;
 335                         if (copy_to_user(addr, &fdq, sizeof(fdq)))
 336                                 return -EFAULT;
 337                         return 0;
 338                 }
 339                 /* We never reach here unless validity check is broken */
 340                 default:
 341                         BUG();
 342         }
 343         return 0;
 344 }
 345
 346 #ifdef CONFIG_BLK_DEV_VROOT
 347 extern struct block_device *vroot_get_real_bdev(struct block_device *);
 348 #endif
 349
 350 /*
 351  * This is the system call interface. This communicates with
 352  * the user-level programs. Currently this only supports diskquota
 353  * calls. Maybe we need to add the process quotas etc. in the future,
 354  * but we probably should use rlimits for that.
 355  */
 356 asmlinkage long sys_quotactl(unsigned int cmd, const char __user *special, qid_t id, void __user *addr)
 357 {
 358         uint cmds, type;
 359         struct super_block *sb = NULL;
 360         struct block_device *bdev;
 361         char *tmp;
 362         int ret;
 363
 364         cmds = cmd >> SUBCMDSHIFT;
 365         type = cmd & SUBCMDMASK;
 366
 367         if (cmds != Q_SYNC || special) {
 368                 tmp = getname(special);
 369                 if (IS_ERR(tmp))
 370                         return PTR_ERR(tmp);
 371                 bdev = lookup_bdev(tmp);
 372                 putname(tmp);
 373                 if (IS_ERR(bdev))
 374                         return PTR_ERR(bdev);
 375 #ifdef CONFIG_BLK_DEV_VROOT
 376                 if (bdev && bdev->bd_inode &&
 377                         imajor(bdev->bd_inode) == VROOT_MAJOR) {
 378                         struct block_device *bdnew =
 379                                 vroot_get_real_bdev(bdev);
 380
 381                         bdput(bdev);
 382                         if (IS_ERR(bdnew))
 383                                 return PTR_ERR(bdnew);
 384                         bdev = bdnew;
 385                 }
 386 #endif
 387                 sb = get_super(bdev);
 388                 bdput(bdev);
 389                 if (!sb)
 390                         return -ENODEV;
 391         }
 392
 393         ret = check_quotactl_valid(sb, type, cmds, id);
 394         if (ret >= 0)
 395                 ret = do_quotactl(sb, type, cmds, id, addr);
 396         if (sb)
 397                 drop_super(sb);
 398
 399         return ret;
 400 }