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
  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))
  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         struct inode *discard[MAXQUOTAS];
 162
 163         sb->s_qcop->quota_sync(sb, type);
 164         /* This is not very clever (and fast) but currently I don't know about
 165          * any other simple way of getting quota data to disk and we must get
 166          * them there for userspace to be visible... */
 167         if (sb->s_op->sync_fs)
 168                 sb->s_op->sync_fs(sb, 1);
 169         sync_blockdev(sb->s_bdev);
 170
 171         /* Now when everything is written we can discard the pagecache so
 172          * that userspace sees the changes. We need i_mutex and so we could
 173          * not do it inside dqonoff_mutex. Moreover we need to be carefull
 174          * about races with quotaoff() (that is the reason why we have own
 175          * reference to inode). */
 176         mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
 177         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 178                 discard[cnt] = NULL;
 179                 if (type != -1 && cnt != type)
 180                         continue;
 181                 if (!sb_has_quota_enabled(sb, cnt))
 182                         continue;
 183                 discard[cnt] = igrab(sb_dqopt(sb)->files[cnt]);
 184         }
 185         mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
 186         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 187                 if (discard[cnt]) {
 188                         mutex_lock(&discard[cnt]->i_mutex);
 189                         truncate_inode_pages(&discard[cnt]->i_data, 0);
 190                         mutex_unlock(&discard[cnt]->i_mutex);
 191                         iput(discard[cnt]);
 192                 }
 193         }
 194 }
 195
 196 void sync_dquots(struct super_block *sb, int type)
 197 {
 198         int cnt, dirty;
 199
 200         if (sb) {
 201                 if (sb->s_qcop->quota_sync)
 202                         quota_sync_sb(sb, type);
 203                 return;
 204         }
 205
 206         spin_lock(&sb_lock);
 207 restart:
 208         list_for_each_entry(sb, &super_blocks, s_list) {
 209                 /* This test just improves performance so it needn't be reliable... */
 210                 for (cnt = 0, dirty = 0; cnt < MAXQUOTAS; cnt++)
 211                         if ((type == cnt || type == -1) && sb_has_quota_enabled(sb, cnt)
 212                             && info_any_dirty(&sb_dqopt(sb)->info[cnt]))
 213                                 dirty = 1;
 214                 if (!dirty)
 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);
 241                         putname(pathname);
 242                         return ret;
 243                 }
 244                 case Q_QUOTAOFF:
 245                         return sb->s_qcop->quota_off(sb, type);
 246
 247                 case Q_GETFMT: {
 248                         __u32 fmt;
 249
 250                         down_read(&sb_dqopt(sb)->dqptr_sem);
 251                         if (!sb_has_quota_enabled(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_PTR(PTR_ERR(tmp));
 353         bdev = lookup_bdev(tmp);
 354         putname(tmp);
 355         if (IS_ERR(bdev))
 356                 return ERR_PTR(PTR_ERR(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 asmlinkage long sys_quotactl(unsigned int cmd, const char __user *special, qid_t id, void __user *addr)
 375 {
 376         uint cmds, type;
 377         struct super_block *sb = NULL;
 378         int ret;
 379
 380         cmds = cmd >> SUBCMDSHIFT;
 381         type = cmd & SUBCMDMASK;
 382
 383         if (cmds != Q_SYNC || special) {
 384                 sb = quotactl_block(special);
 385                 if (IS_ERR(sb))
 386                         return PTR_ERR(sb);
 387         }
 388
 389         ret = check_quotactl_valid(sb, type, cmds, id);
 390         if (ret >= 0)
 391                 ret = do_quotactl(sb, type, cmds, id, addr);
 392         if (sb)
 393                 drop_super(sb);
 394
 395         return ret;
 396 }