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
  17 /* Check validity of quotactl */
  18 static int check_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
  19 {
  20         if (type >= MAXQUOTAS)
  21                 return -EINVAL;
  22         if (!sb && cmd != Q_SYNC)
  23                 return -ENODEV;
  24         /* Is operation supported? */
  25         if (sb && !sb->s_qcop)
  26                 return -ENOSYS;
  27
  28         switch (cmd) {
  29                 case Q_GETFMT:
  30                         break;
  31                 case Q_QUOTAON:
  32                         if (!sb->s_qcop->quota_on)
  33                                 return -ENOSYS;
  34                         break;
  35                 case Q_QUOTAOFF:
  36                         if (!sb->s_qcop->quota_off)
  37                                 return -ENOSYS;
  38                         break;
  39                 case Q_SETINFO:
  40                         if (!sb->s_qcop->set_info)
  41                                 return -ENOSYS;
  42                         break;
  43                 case Q_GETINFO:
  44                         if (!sb->s_qcop->get_info)
  45                                 return -ENOSYS;
  46                         break;
  47                 case Q_SETQUOTA:
  48                         if (!sb->s_qcop->set_dqblk)
  49                                 return -ENOSYS;
  50                         break;
  51                 case Q_GETQUOTA:
  52                         if (!sb->s_qcop->get_dqblk)
  53                                 return -ENOSYS;
  54                         break;
  55                 case Q_SYNC:
  56                         if (sb && !sb->s_qcop->quota_sync)
  57                                 return -ENOSYS;
  58                         break;
  59                 case Q_XQUOTAON:
  60                 case Q_XQUOTAOFF:
  61                 case Q_XQUOTARM:
  62                         if (!sb->s_qcop->set_xstate)
  63                                 return -ENOSYS;
  64                         break;
  65                 case Q_XGETQSTAT:
  66                         if (!sb->s_qcop->get_xstate)
  67                                 return -ENOSYS;
  68                         break;
  69                 case Q_XSETQLIM:
  70                         if (!sb->s_qcop->set_xquota)
  71                                 return -ENOSYS;
  72                         break;
  73                 case Q_XGETQUOTA:
  74                         if (!sb->s_qcop->get_xquota)
  75                                 return -ENOSYS;
  76                         break;
  77                 default:
  78                         return -EINVAL;
  79         }
  80
  81         /* Is quota turned on for commands which need it? */
  82         switch (cmd) {
  83                 case Q_GETFMT:
  84                 case Q_GETINFO:
  85                 case Q_QUOTAOFF:
  86                 case Q_SETINFO:
  87                 case Q_SETQUOTA:
  88                 case Q_GETQUOTA:
  89                         /* This is just informative test so we are satisfied without a lock */
  90                         if (!sb_has_quota_enabled(sb, type))
  91                                 return -ESRCH;
  92         }
  93         /* Check privileges */
  94         if (cmd == Q_GETQUOTA || cmd == Q_XGETQUOTA) {
  95                 if (((type == USRQUOTA && current->euid != id) ||
  96                      (type == GRPQUOTA && !in_egroup_p(id))) &&
  97                     !capable(CAP_SYS_ADMIN))
  98                         return -EPERM;
  99         }
 100         else if (cmd != Q_GETFMT && cmd != Q_SYNC && cmd != Q_GETINFO && cmd != Q_XGETQSTAT)
 101                 if (!capable(CAP_SYS_ADMIN))
 102                         return -EPERM;
 103
 104         return security_quotactl (cmd, type, id, sb);
 105 }
 106
 107 static struct super_block *get_super_to_sync(int type)
 108 {
 109         struct list_head *head;
 110         int cnt, dirty;
 111
 112 restart:
 113         spin_lock(&sb_lock);
 114         list_for_each(head, &super_blocks) {
 115                 struct super_block *sb = list_entry(head, struct super_block, s_list);
 116
 117                 /* This test just improves performance so it needn't be reliable... */
 118                 for (cnt = 0, dirty = 0; cnt < MAXQUOTAS; cnt++)
 119                         if ((type == cnt || type == -1) && sb_has_quota_enabled(sb, cnt)
 120                             && info_any_dirty(&sb_dqopt(sb)->info[cnt]))
 121                                 dirty = 1;
 122                 if (!dirty)
 123                         continue;
 124                 sb->s_count++;
 125                 spin_unlock(&sb_lock);
 126                 down_read(&sb->s_umount);
 127                 if (!sb->s_root) {
 128                         drop_super(sb);
 129                         goto restart;
 130                 }
 131                 return sb;
 132         }
 133         spin_unlock(&sb_lock);
 134         return NULL;
 135 }
 136
 137 void sync_dquots(struct super_block *sb, int type)
 138 {
 139         if (sb) {
 140                 if (sb->s_qcop->quota_sync)
 141                         sb->s_qcop->quota_sync(sb, type);
 142         }
 143         else {
 144                 while ((sb = get_super_to_sync(type)) != 0) {
 145                         if (sb->s_qcop->quota_sync)
 146                                 sb->s_qcop->quota_sync(sb, type);
 147                         drop_super(sb);
 148                 }
 149         }
 150 }
 151
 152 /* Copy parameters and call proper function */
 153 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, void __user *addr)
 154 {
 155         int ret;
 156
 157         switch (cmd) {
 158                 case Q_QUOTAON: {
 159                         char *pathname;
 160
 161                         if (IS_ERR(pathname = getname(addr)))
 162                                 return PTR_ERR(pathname);
 163                         ret = sb->s_qcop->quota_on(sb, type, id, pathname);
 164                         putname(pathname);
 165                         return ret;
 166                 }
 167                 case Q_QUOTAOFF:
 168                         return sb->s_qcop->quota_off(sb, type);
 169
 170                 case Q_GETFMT: {
 171                         __u32 fmt;
 172
 173                         down_read(&sb_dqopt(sb)->dqptr_sem);
 174                         if (!sb_has_quota_enabled(sb, type)) {
 175                                 up_read(&sb_dqopt(sb)->dqptr_sem);
 176                                 return -ESRCH;
 177                         }
 178                         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
 179                         up_read(&sb_dqopt(sb)->dqptr_sem);
 180                         if (copy_to_user(addr, &fmt, sizeof(fmt)))
 181                                 return -EFAULT;
 182                         return 0;
 183                 }
 184                 case Q_GETINFO: {
 185                         struct if_dqinfo info;
 186
 187                         if ((ret = sb->s_qcop->get_info(sb, type, &info)))
 188                                 return ret;
 189                         if (copy_to_user(addr, &info, sizeof(info)))
 190                                 return -EFAULT;
 191                         return 0;
 192                 }
 193                 case Q_SETINFO: {
 194                         struct if_dqinfo info;
 195
 196                         if (copy_from_user(&info, addr, sizeof(info)))
 197                                 return -EFAULT;
 198                         return sb->s_qcop->set_info(sb, type, &info);
 199                 }
 200                 case Q_GETQUOTA: {
 201                         struct if_dqblk idq;
 202
 203                         if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)))
 204                                 return ret;
 205                         if (copy_to_user(addr, &idq, sizeof(idq)))
 206                                 return -EFAULT;
 207                         return 0;
 208                 }
 209                 case Q_SETQUOTA: {
 210                         struct if_dqblk idq;
 211
 212                         if (copy_from_user(&idq, addr, sizeof(idq)))
 213                                 return -EFAULT;
 214                         return sb->s_qcop->set_dqblk(sb, type, id, &idq);
 215                 }
 216                 case Q_SYNC:
 217                         sync_dquots(sb, type);
 218                         return 0;
 219
 220                 case Q_XQUOTAON:
 221                 case Q_XQUOTAOFF:
 222                 case Q_XQUOTARM: {
 223                         __u32 flags;
 224
 225                         if (copy_from_user(&flags, addr, sizeof(flags)))
 226                                 return -EFAULT;
 227                         return sb->s_qcop->set_xstate(sb, flags, cmd);
 228                 }
 229                 case Q_XGETQSTAT: {
 230                         struct fs_quota_stat fqs;
 231
 232                         if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
 233                                 return ret;
 234                         if (copy_to_user(addr, &fqs, sizeof(fqs)))
 235                                 return -EFAULT;
 236                         return 0;
 237                 }
 238                 case Q_XSETQLIM: {
 239                         struct fs_disk_quota fdq;
 240
 241                         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 242                                 return -EFAULT;
 243                        return sb->s_qcop->set_xquota(sb, type, id, &fdq);
 244                 }
 245                 case Q_XGETQUOTA: {
 246                         struct fs_disk_quota fdq;
 247
 248                         if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq)))
 249                                 return ret;
 250                         if (copy_to_user(addr, &fdq, sizeof(fdq)))
 251                                 return -EFAULT;
 252                         return 0;
 253                 }
 254                 /* We never reach here unless validity check is broken */
 255                 default:
 256                         BUG();
 257         }
 258         return 0;
 259 }
 260
 261 /*
 262  * This is the system call interface. This communicates with
 263  * the user-level programs. Currently this only supports diskquota
 264  * calls. Maybe we need to add the process quotas etc. in the future,
 265  * but we probably should use rlimits for that.
 266  */
 267 asmlinkage long sys_quotactl(unsigned int cmd, const char __user *special, qid_t id, void __user *addr)
 268 {
 269         uint cmds, type;
 270         struct super_block *sb = NULL;
 271         struct block_device *bdev;
 272         char *tmp;
 273         int ret;
 274
 275         cmds = cmd >> SUBCMDSHIFT;
 276         type = cmd & SUBCMDMASK;
 277
 278         if (cmds != Q_SYNC || special) {
 279                 tmp = getname(special);
 280                 if (IS_ERR(tmp))
 281                         return PTR_ERR(tmp);
 282                 bdev = lookup_bdev(tmp);
 283                 putname(tmp);
 284                 if (IS_ERR(bdev))
 285                         return PTR_ERR(bdev);
 286                 sb = get_super(bdev);
 287                 bdput(bdev);
 288                 if (!sb)
 289                         return -ENODEV;
 290         }
 291
 292         ret = check_quotactl_valid(sb, type, cmds, id);
 293         if (ret >= 0)
 294                 ret = do_quotactl(sb, type, cmds, id, addr);
 295         if (sb)
 296                 drop_super(sb);
 297
 298         return ret;
 299 }