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/security.h>
  15 #include <linux/syscalls.h>
  16 #include <linux/buffer_head.h>
  17 #include <linux/capability.h>
  18 #include <linux/quotaops.h>
  19
  20 /* Check validity of generic quotactl commands */
  21 static int generic_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
  22 {
  23         if (type >= MAXQUOTAS)
  24                 return -EINVAL;
  25         if (!sb && cmd != Q_SYNC)
  26                 return -ENODEV;
  27         /* Is operation supported? */
  28         if (sb && !sb->s_qcop)
  29                 return -ENOSYS;
  30
  31         switch (cmd) {
  32                 case Q_GETFMT:
  33                         break;
  34                 case Q_QUOTAON:
  35                         if (!sb->s_qcop->quota_on)
  36                                 return -ENOSYS;
  37                         break;
  38                 case Q_QUOTAOFF:
  39                         if (!sb->s_qcop->quota_off)
  40                                 return -ENOSYS;
  41                         break;
  42                 case Q_SETINFO:
  43                         if (!sb->s_qcop->set_info)
  44                                 return -ENOSYS;
  45                         break;
  46                 case Q_GETINFO:
  47                         if (!sb->s_qcop->get_info)
  48                                 return -ENOSYS;
  49                         break;
  50                 case Q_SETQUOTA:
  51                         if (!sb->s_qcop->set_dqblk)
  52                                 return -ENOSYS;
  53                         break;
  54                 case Q_GETQUOTA:
  55                         if (!sb->s_qcop->get_dqblk)
  56                                 return -ENOSYS;
  57                         break;
  58                 case Q_SYNC:
  59                         if (sb && !sb->s_qcop->quota_sync)
  60                                 return -ENOSYS;
  61                         break;
  62                 default:
  63                         return -EINVAL;
  64         }
  65
  66         /* Is quota turned on for commands which need it? */
  67         switch (cmd) {
  68                 case Q_GETFMT:
  69                 case Q_GETINFO:
  70                 case Q_QUOTAOFF:
  71                 case Q_SETINFO:
  72                 case Q_SETQUOTA:
  73                 case Q_GETQUOTA:
  74                         /* This is just informative test so we are satisfied without a lock */
  75                         if (!sb_has_quota_enabled(sb, type))
  76                                 return -ESRCH;
  77         }
  78
  79         /* Check privileges */
  80         if (cmd == Q_GETQUOTA) {
  81                 if (((type == USRQUOTA && current->euid != id) ||
  82                      (type == GRPQUOTA && !in_egroup_p(id))) &&
  83                     !capable(CAP_SYS_ADMIN))
  84                         return -EPERM;
  85         }
  86         else if (cmd != Q_GETFMT && cmd != Q_SYNC && cmd != Q_GETINFO)
  87                 if (!capable(CAP_SYS_ADMIN))
  88                         return -EPERM;
  89
  90         return 0;
  91 }
  92
  93 /* Check validity of XFS Quota Manager commands */
  94 static int xqm_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
  95 {
  96         if (type >= XQM_MAXQUOTAS)
  97                 return -EINVAL;
  98         if (!sb)
  99                 return -ENODEV;
 100         if (!sb->s_qcop)
 101                 return -ENOSYS;
 102
 103         switch (cmd) {
 104                 case Q_XQUOTAON:
 105                 case Q_XQUOTAOFF:
 106                 case Q_XQUOTARM:
 107                         if (!sb->s_qcop->set_xstate)
 108                                 return -ENOSYS;
 109                         break;
 110                 case Q_XGETQSTAT:
 111                         if (!sb->s_qcop->get_xstate)
 112                                 return -ENOSYS;
 113                         break;
 114                 case Q_XSETQLIM:
 115                         if (!sb->s_qcop->set_xquota)
 116                                 return -ENOSYS;
 117                         break;
 118                 case Q_XGETQUOTA:
 119                         if (!sb->s_qcop->get_xquota)
 120                                 return -ENOSYS;
 121                         break;
 122                 case Q_XQUOTASYNC:
 123                         if (!sb->s_qcop->quota_sync)
 124                                 return -ENOSYS;
 125                         break;
 126                 default:
 127                         return -EINVAL;
 128         }
 129
 130         /* Check privileges */
 131         if (cmd == Q_XGETQUOTA) {
 132                 if (((type == XQM_USRQUOTA && current->euid != id) ||
 133                      (type == XQM_GRPQUOTA && !in_egroup_p(id))) &&
 134                      !capable(CAP_SYS_ADMIN))
 135                         return -EPERM;
 136         } else if (cmd != Q_XGETQSTAT && cmd != Q_XQUOTASYNC) {
 137                 if (!capable(CAP_SYS_ADMIN))
 138                         return -EPERM;
 139         }
 140
 141         return 0;
 142 }
 143
 144 static int check_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
 145 {
 146         int error;
 147
 148         if (XQM_COMMAND(cmd))
 149                 error = xqm_quotactl_valid(sb, type, cmd, id);
 150         else
 151                 error = generic_quotactl_valid(sb, type, cmd, id);
 152         if (!error)
 153                 error = security_quotactl(cmd, type, id, sb);
 154         return error;
 155 }
 156
 157 static void quota_sync_sb(struct super_block *sb, int type)
 158 {
 159         int cnt;
 160         struct inode *discard[MAXQUOTAS];
 161
 162         sb->s_qcop->quota_sync(sb, type);
 163         /* This is not very clever (and fast) but currently I don't know about
 164          * any other simple way of getting quota data to disk and we must get
 165          * them there for userspace to be visible... */
 166         if (sb->s_op->sync_fs)
 167                 sb->s_op->sync_fs(sb, 1);
 168         sync_blockdev(sb->s_bdev);
 169
 170         /* Now when everything is written we can discard the pagecache so
 171          * that userspace sees the changes. We need i_mutex and so we could
 172          * not do it inside dqonoff_mutex. Moreover we need to be carefull
 173          * about races with quotaoff() (that is the reason why we have own
 174          * reference to inode). */
 175         mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
 176         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 177                 discard[cnt] = NULL;
 178                 if (type != -1 && cnt != type)
 179                         continue;
 180                 if (!sb_has_quota_enabled(sb, cnt))
 181                         continue;
 182                 discard[cnt] = igrab(sb_dqopt(sb)->files[cnt]);
 183         }
 184         mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
 185         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 186                 if (discard[cnt]) {
 187                         mutex_lock(&discard[cnt]->i_mutex);
 188                         truncate_inode_pages(&discard[cnt]->i_data, 0);
 189                         mutex_unlock(&discard[cnt]->i_mutex);
 190                         iput(discard[cnt]);
 191                 }
 192         }
 193 }
 194
 195 void sync_dquots(struct super_block *sb, int type)
 196 {
 197         int cnt, dirty;
 198
 199         if (sb) {
 200                 if (sb->s_qcop->quota_sync)
 201                         quota_sync_sb(sb, type);
 202                 return;
 203         }
 204
 205         spin_lock(&sb_lock);
 206 restart:
 207         list_for_each_entry(sb, &super_blocks, s_list) {
 208                 /* This test just improves performance so it needn't be reliable... */
 209                 for (cnt = 0, dirty = 0; cnt < MAXQUOTAS; cnt++)
 210                         if ((type == cnt || type == -1) && sb_has_quota_enabled(sb, cnt)
 211                             && info_any_dirty(&sb_dqopt(sb)->info[cnt]))
 212                                 dirty = 1;
 213                 if (!dirty)
 214                         continue;
 215                 sb->s_count++;
 216                 spin_unlock(&sb_lock);
 217                 down_read(&sb->s_umount);
 218                 if (sb->s_root && sb->s_qcop->quota_sync)
 219                         quota_sync_sb(sb, type);
 220                 up_read(&sb->s_umount);
 221                 spin_lock(&sb_lock);
 222                 if (__put_super_and_need_restart(sb))
 223                         goto restart;
 224         }
 225         spin_unlock(&sb_lock);
 226 }
 227
 228 /* Copy parameters and call proper function */
 229 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, void __user *addr)
 230 {
 231         int ret;
 232
 233         switch (cmd) {
 234                 case Q_QUOTAON: {
 235                         char *pathname;
 236
 237                         if (IS_ERR(pathname = getname(addr)))
 238                                 return PTR_ERR(pathname);
 239                         ret = sb->s_qcop->quota_on(sb, type, id, pathname);
 240                         putname(pathname);
 241                         return ret;
 242                 }
 243                 case Q_QUOTAOFF:
 244                         return sb->s_qcop->quota_off(sb, type);
 245
 246                 case Q_GETFMT: {
 247                         __u32 fmt;
 248
 249                         down_read(&sb_dqopt(sb)->dqptr_sem);
 250                         if (!sb_has_quota_enabled(sb, type)) {
 251                                 up_read(&sb_dqopt(sb)->dqptr_sem);
 252                                 return -ESRCH;
 253                         }
 254                         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
 255                         up_read(&sb_dqopt(sb)->dqptr_sem);
 256                         if (copy_to_user(addr, &fmt, sizeof(fmt)))
 257                                 return -EFAULT;
 258                         return 0;
 259                 }
 260                 case Q_GETINFO: {
 261                         struct if_dqinfo info;
 262
 263                         if ((ret = sb->s_qcop->get_info(sb, type, &info)))
 264                                 return ret;
 265                         if (copy_to_user(addr, &info, sizeof(info)))
 266                                 return -EFAULT;
 267                         return 0;
 268                 }
 269                 case Q_SETINFO: {
 270                         struct if_dqinfo info;
 271
 272                         if (copy_from_user(&info, addr, sizeof(info)))
 273                                 return -EFAULT;
 274                         return sb->s_qcop->set_info(sb, type, &info);
 275                 }
 276                 case Q_GETQUOTA: {
 277                         struct if_dqblk idq;
 278
 279                         if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)))
 280                                 return ret;
 281                         if (copy_to_user(addr, &idq, sizeof(idq)))
 282                                 return -EFAULT;
 283                         return 0;
 284                 }
 285                 case Q_SETQUOTA: {
 286                         struct if_dqblk idq;
 287
 288                         if (copy_from_user(&idq, addr, sizeof(idq)))
 289                                 return -EFAULT;
 290                         return sb->s_qcop->set_dqblk(sb, type, id, &idq);
 291                 }
 292                 case Q_SYNC:
 293                         sync_dquots(sb, type);
 294                         return 0;
 295
 296                 case Q_XQUOTAON:
 297                 case Q_XQUOTAOFF:
 298                 case Q_XQUOTARM: {
 299                         __u32 flags;
 300
 301                         if (copy_from_user(&flags, addr, sizeof(flags)))
 302                                 return -EFAULT;
 303                         return sb->s_qcop->set_xstate(sb, flags, cmd);
 304                 }
 305                 case Q_XGETQSTAT: {
 306                         struct fs_quota_stat fqs;
 307
 308                         if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
 309                                 return ret;
 310                         if (copy_to_user(addr, &fqs, sizeof(fqs)))
 311                                 return -EFAULT;
 312                         return 0;
 313                 }
 314                 case Q_XSETQLIM: {
 315                         struct fs_disk_quota fdq;
 316
 317                         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 318                                 return -EFAULT;
 319                        return sb->s_qcop->set_xquota(sb, type, id, &fdq);
 320                 }
 321                 case Q_XGETQUOTA: {
 322                         struct fs_disk_quota fdq;
 323
 324                         if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq)))
 325                                 return ret;
 326                         if (copy_to_user(addr, &fdq, sizeof(fdq)))
 327                                 return -EFAULT;
 328                         return 0;
 329                 }
 330                 case Q_XQUOTASYNC:
 331                         return sb->s_qcop->quota_sync(sb, type);
 332                 /* We never reach here unless validity check is broken */
 333                 default:
 334                         BUG();
 335         }
 336         return 0;
 337 }
 338
 339 /*
 340  * look up a superblock on which quota ops will be performed
 341  * - use the name of a block device to find the superblock thereon
 342  */
 343 static inline struct super_block *quotactl_block(const char __user *special)
 344 {
 345 #ifdef CONFIG_BLOCK
 346         struct block_device *bdev;
 347         struct super_block *sb;
 348         char *tmp = getname(special);
 349
 350         if (IS_ERR(tmp))
 351                 return ERR_PTR(PTR_ERR(tmp));
 352         bdev = lookup_bdev(tmp);
 353         putname(tmp);
 354         if (IS_ERR(bdev))
 355                 return ERR_PTR(PTR_ERR(bdev));
 356         sb = get_super(bdev);
 357         bdput(bdev);
 358         if (!sb)
 359                 return ERR_PTR(-ENODEV);
 360
 361         return sb;
 362 #else
 363         return ERR_PTR(-ENODEV);
 364 #endif
 365 }
 366
 367 /*
 368  * This is the system call interface. This communicates with
 369  * the user-level programs. Currently this only supports diskquota
 370  * calls. Maybe we need to add the process quotas etc. in the future,
 371  * but we probably should use rlimits for that.
 372  */
 373 asmlinkage long sys_quotactl(unsigned int cmd, const char __user *special, qid_t id, void __user *addr)
 374 {
 375         uint cmds, type;
 376         struct super_block *sb = NULL;
 377         int ret;
 378
 379         cmds = cmd >> SUBCMDSHIFT;
 380         type = cmd & SUBCMDMASK;
 381
 382         if (cmds != Q_SYNC || special) {
 383                 sb = quotactl_block(special);
 384                 if (IS_ERR(sb))
 385                         return PTR_ERR(sb);
 386         }
 387
 388         ret = check_quotactl_valid(sb, type, cmds, id);
 389         if (ret >= 0)
 390                 ret = do_quotactl(sb, type, cmds, id, addr);
 391         if (sb)
 392                 drop_super(sb);
 393
 394         return ret;
 395 }