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