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