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 struct super_block *get_super_to_sync(int type)
 153 {
 154         struct list_head *head;
 155         int cnt, dirty;
 156
 157 restart:
 158         spin_lock(&sb_lock);
 159         list_for_each(head, &super_blocks) {
 160                 struct super_block *sb = list_entry(head, struct super_block, s_list);
 161
 162                 /* This test just improves performance so it needn't be reliable... */
 163                 for (cnt = 0, dirty = 0; cnt < MAXQUOTAS; cnt++)
 164                         if ((type == cnt || type == -1) && sb_has_quota_enabled(sb, cnt)
 165                             && info_any_dirty(&sb_dqopt(sb)->info[cnt]))
 166                                 dirty = 1;
 167                 if (!dirty)
 168                         continue;
 169                 sb->s_count++;
 170                 spin_unlock(&sb_lock);
 171                 down_read(&sb->s_umount);
 172                 if (!sb->s_root) {
 173                         drop_super(sb);
 174                         goto restart;
 175                 }
 176                 return sb;
 177         }
 178         spin_unlock(&sb_lock);
 179         return NULL;
 180 }
 181
 182 static void quota_sync_sb(struct super_block *sb, int type)
 183 {
 184         int cnt;
 185         struct inode *discard[MAXQUOTAS];
 186
 187         sb->s_qcop->quota_sync(sb, type);
 188         /* This is not very clever (and fast) but currently I don't know about
 189          * any other simple way of getting quota data to disk and we must get
 190          * them there for userspace to be visible... */
 191         if (sb->s_op->sync_fs)
 192                 sb->s_op->sync_fs(sb, 1);
 193         sync_blockdev(sb->s_bdev);
 194
 195         /* Now when everything is written we can discard the pagecache so
 196          * that userspace sees the changes. We need i_sem and so we could
 197          * not do it inside dqonoff_sem. Moreover we need to be carefull
 198          * about races with quotaoff() (that is the reason why we have own
 199          * reference to inode). */
 200         down(&sb_dqopt(sb)->dqonoff_sem);
 201         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 202                 discard[cnt] = NULL;
 203                 if (type != -1 && cnt != type)
 204                         continue;
 205                 if (!sb_has_quota_enabled(sb, cnt))
 206                         continue;
 207                 discard[cnt] = igrab(sb_dqopt(sb)->files[cnt]);
 208         }
 209         up(&sb_dqopt(sb)->dqonoff_sem);
 210         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 211                 if (discard[cnt]) {
 212                         down(&discard[cnt]->i_sem);
 213                         truncate_inode_pages(&discard[cnt]->i_data, 0);
 214                         up(&discard[cnt]->i_sem);
 215                         iput(discard[cnt]);
 216                 }
 217         }
 218 }
 219
 220 void sync_dquots(struct super_block *sb, int type)
 221 {
 222         if (sb) {
 223                 if (sb->s_qcop->quota_sync)
 224                         quota_sync_sb(sb, type);
 225         }
 226         else {
 227                 while ((sb = get_super_to_sync(type)) != NULL) {
 228                         if (sb->s_qcop->quota_sync)
 229                                 quota_sync_sb(sb, type);
 230                         drop_super(sb);
 231                 }
 232         }
 233 }
 234
 235 /* Copy parameters and call proper function */
 236 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, void __user *addr)
 237 {
 238         int ret;
 239
 240         switch (cmd) {
 241                 case Q_QUOTAON: {
 242                         char *pathname;
 243
 244                         if (IS_ERR(pathname = getname(addr)))
 245                                 return PTR_ERR(pathname);
 246                         ret = sb->s_qcop->quota_on(sb, type, id, pathname);
 247                         putname(pathname);
 248                         return ret;
 249                 }
 250                 case Q_QUOTAOFF:
 251                         return sb->s_qcop->quota_off(sb, type);
 252
 253                 case Q_GETFMT: {
 254                         __u32 fmt;
 255
 256                         down_read(&sb_dqopt(sb)->dqptr_sem);
 257                         if (!sb_has_quota_enabled(sb, type)) {
 258                                 up_read(&sb_dqopt(sb)->dqptr_sem);
 259                                 return -ESRCH;
 260                         }
 261                         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
 262                         up_read(&sb_dqopt(sb)->dqptr_sem);
 263                         if (copy_to_user(addr, &fmt, sizeof(fmt)))
 264                                 return -EFAULT;
 265                         return 0;
 266                 }
 267                 case Q_GETINFO: {
 268                         struct if_dqinfo info;
 269
 270                         if ((ret = sb->s_qcop->get_info(sb, type, &info)))
 271                                 return ret;
 272                         if (copy_to_user(addr, &info, sizeof(info)))
 273                                 return -EFAULT;
 274                         return 0;
 275                 }
 276                 case Q_SETINFO: {
 277                         struct if_dqinfo info;
 278
 279                         if (copy_from_user(&info, addr, sizeof(info)))
 280                                 return -EFAULT;
 281                         return sb->s_qcop->set_info(sb, type, &info);
 282                 }
 283                 case Q_GETQUOTA: {
 284                         struct if_dqblk idq;
 285
 286                         if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)))
 287                                 return ret;
 288                         if (copy_to_user(addr, &idq, sizeof(idq)))
 289                                 return -EFAULT;
 290                         return 0;
 291                 }
 292                 case Q_SETQUOTA: {
 293                         struct if_dqblk idq;
 294
 295                         if (copy_from_user(&idq, addr, sizeof(idq)))
 296                                 return -EFAULT;
 297                         return sb->s_qcop->set_dqblk(sb, type, id, &idq);
 298                 }
 299                 case Q_SYNC:
 300                         sync_dquots(sb, type);
 301                         return 0;
 302
 303                 case Q_XQUOTAON:
 304                 case Q_XQUOTAOFF:
 305                 case Q_XQUOTARM: {
 306                         __u32 flags;
 307
 308                         if (copy_from_user(&flags, addr, sizeof(flags)))
 309                                 return -EFAULT;
 310                         return sb->s_qcop->set_xstate(sb, flags, cmd);
 311                 }
 312                 case Q_XGETQSTAT: {
 313                         struct fs_quota_stat fqs;
 314
 315                         if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
 316                                 return ret;
 317                         if (copy_to_user(addr, &fqs, sizeof(fqs)))
 318                                 return -EFAULT;
 319                         return 0;
 320                 }
 321                 case Q_XSETQLIM: {
 322                         struct fs_disk_quota fdq;
 323
 324                         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 325                                 return -EFAULT;
 326                        return sb->s_qcop->set_xquota(sb, type, id, &fdq);
 327                 }
 328                 case Q_XGETQUOTA: {
 329                         struct fs_disk_quota fdq;
 330
 331                         if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq)))
 332                                 return ret;
 333                         if (copy_to_user(addr, &fdq, sizeof(fdq)))
 334                                 return -EFAULT;
 335                         return 0;
 336                 }
 337                 /* We never reach here unless validity check is broken */
 338                 default:
 339                         BUG();
 340         }
 341         return 0;
 342 }
 343
 344 /*
 345  * This is the system call interface. This communicates with
 346  * the user-level programs. Currently this only supports diskquota
 347  * calls. Maybe we need to add the process quotas etc. in the future,
 348  * but we probably should use rlimits for that.
 349  */
 350 asmlinkage long sys_quotactl(unsigned int cmd, const char __user *special, qid_t id, void __user *addr)
 351 {
 352         uint cmds, type;
 353         struct super_block *sb = NULL;
 354         struct block_device *bdev;
 355         char *tmp;
 356         int ret;
 357
 358         cmds = cmd >> SUBCMDSHIFT;
 359         type = cmd & SUBCMDMASK;
 360
 361         if (cmds != Q_SYNC || special) {
 362                 tmp = getname(special);
 363                 if (IS_ERR(tmp))
 364                         return PTR_ERR(tmp);
 365                 bdev = lookup_bdev(tmp);
 366                 putname(tmp);
 367                 if (IS_ERR(bdev))
 368                         return PTR_ERR(bdev);
 369                 sb = get_super(bdev);
 370                 bdput(bdev);
 371                 if (!sb)
 372                         return -ENODEV;
 373         }
 374
 375         ret = check_quotactl_valid(sb, type, cmds, id);
 376         if (ret >= 0)
 377                 ret = do_quotactl(sb, type, cmds, id, addr);
 378         if (sb)
 379                 drop_super(sb);
 380
 381         return ret;
 382 }