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         /* Is operation supported? */
  23         if (!sb->s_qcop)
  24                 return -ENOSYS;
  25
  26         switch (cmd) {
  27                 case Q_GETFMT:
  28                         break;
  29                 case Q_QUOTAON:
  30                         if (!sb->s_qcop->quota_on)
  31                                 return -ENOSYS;
  32                         break;
  33                 case Q_QUOTAOFF:
  34                         if (!sb->s_qcop->quota_off)
  35                                 return -ENOSYS;
  36                         break;
  37                 case Q_SETINFO:
  38                         if (!sb->s_qcop->set_info)
  39                                 return -ENOSYS;
  40                         break;
  41                 case Q_GETINFO:
  42                         if (!sb->s_qcop->get_info)
  43                                 return -ENOSYS;
  44                         break;
  45                 case Q_SETQUOTA:
  46                         if (!sb->s_qcop->set_dqblk)
  47                                 return -ENOSYS;
  48                         break;
  49                 case Q_GETQUOTA:
  50                         if (!sb->s_qcop->get_dqblk)
  51                                 return -ENOSYS;
  52                         break;
  53                 case Q_SYNC:
  54                         if (!sb->s_qcop->quota_sync)
  55                                 return -ENOSYS;
  56                         break;
  57                 case Q_XQUOTAON:
  58                 case Q_XQUOTAOFF:
  59                 case Q_XQUOTARM:
  60                         if (!sb->s_qcop->set_xstate)
  61                                 return -ENOSYS;
  62                         break;
  63                 case Q_XGETQSTAT:
  64                         if (!sb->s_qcop->get_xstate)
  65                                 return -ENOSYS;
  66                         break;
  67                 case Q_XSETQLIM:
  68                         if (!sb->s_qcop->set_xquota)
  69                                 return -ENOSYS;
  70                         break;
  71                 case Q_XGETQUOTA:
  72                         if (!sb->s_qcop->get_xquota)
  73                                 return -ENOSYS;
  74                         break;
  75                 default:
  76                         return -EINVAL;
  77         }
  78
  79         /* Is quota turned on for commands which need it? */
  80         switch (cmd) {
  81                 case Q_GETFMT:
  82                 case Q_GETINFO:
  83                 case Q_QUOTAOFF:
  84                 case Q_SETINFO:
  85                 case Q_SETQUOTA:
  86                 case Q_GETQUOTA:
  87                         if (!sb_has_quota_enabled(sb, type))
  88                                 return -ESRCH;
  89         }
  90         /* Check privileges */
  91         if (cmd == Q_GETQUOTA || cmd == Q_XGETQUOTA) {
  92                 if (((type == USRQUOTA && current->euid != id) ||
  93                      (type == GRPQUOTA && !in_egroup_p(id))) &&
  94                     !capable(CAP_SYS_ADMIN))
  95                         return -EPERM;
  96         }
  97         else if (cmd != Q_GETFMT && cmd != Q_SYNC && cmd != Q_GETINFO && cmd != Q_XGETQSTAT)
  98                 if (!capable(CAP_SYS_ADMIN))
  99                         return -EPERM;
 100
 101         return security_ops->quotactl (cmd, type, id, sb);
 102 }
 103
 104 /* Resolve device pathname to superblock */
 105 static struct super_block *resolve_dev(const char *path)
 106 {
 107         int ret;
 108         mode_t mode;
 109         struct nameidata nd;
 110         struct block_device *bdev;
 111         struct super_block *sb;
 112
 113         ret = user_path_walk(path, &nd);
 114         if (ret)
 115                 goto out;
 116
 117         bdev = nd.dentry->d_inode->i_bdev;
 118         mode = nd.dentry->d_inode->i_mode;
 119         path_release(&nd);
 120
 121         ret = -ENOTBLK;
 122         if (!S_ISBLK(mode))
 123                 goto out;
 124         ret = -ENODEV;
 125         sb = get_super(bdev);
 126         if (!sb)
 127                 goto out;
 128         return sb;
 129 out:
 130         return ERR_PTR(ret);
 131 }
 132
 133 /* Copy parameters and call proper function */
 134 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, caddr_t addr)
 135 {
 136         int ret;
 137
 138         switch (cmd) {
 139                 case Q_QUOTAON: {
 140                         char *pathname;
 141
 142                         if (IS_ERR(pathname = getname(addr)))
 143                                 return PTR_ERR(pathname);
 144                         ret = sb->s_qcop->quota_on(sb, type, id, pathname);
 145                         putname(pathname);
 146                         return ret;
 147                 }
 148                 case Q_QUOTAOFF:
 149                         return sb->s_qcop->quota_off(sb, type);
 150
 151                 case Q_GETFMT: {
 152                         __u32 fmt;
 153
 154                         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
 155                         if (copy_to_user(addr, &fmt, sizeof(fmt)))
 156                                 return -EFAULT;
 157                         return 0;
 158                 }
 159                 case Q_GETINFO: {
 160                         struct if_dqinfo info;
 161
 162                         if ((ret = sb->s_qcop->get_info(sb, type, &info)))
 163                                 return ret;
 164                         if (copy_to_user(addr, &info, sizeof(info)))
 165                                 return -EFAULT;
 166                         return 0;
 167                 }
 168                 case Q_SETINFO: {
 169                         struct if_dqinfo info;
 170
 171                         if (copy_from_user(&info, addr, sizeof(info)))
 172                                 return -EFAULT;
 173                         return sb->s_qcop->set_info(sb, type, &info);
 174                 }
 175                 case Q_GETQUOTA: {
 176                         struct if_dqblk idq;
 177
 178                         if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)))
 179                                 return ret;
 180                         if (copy_to_user(addr, &idq, sizeof(idq)))
 181                                 return -EFAULT;
 182                         return 0;
 183                 }
 184                 case Q_SETQUOTA: {
 185                         struct if_dqblk idq;
 186
 187                         if (copy_from_user(&idq, addr, sizeof(idq)))
 188                                 return -EFAULT;
 189                         return sb->s_qcop->set_dqblk(sb, type, id, &idq);
 190                 }
 191                 case Q_SYNC:
 192                         return sb->s_qcop->quota_sync(sb, type);
 193
 194                 case Q_XQUOTAON:
 195                 case Q_XQUOTAOFF:
 196                 case Q_XQUOTARM: {
 197                         __u32 flags;
 198
 199                         if (copy_from_user(&flags, addr, sizeof(flags)))
 200                                 return -EFAULT;
 201                         return sb->s_qcop->set_xstate(sb, flags, cmd);
 202                 }
 203                 case Q_XGETQSTAT: {
 204                         struct fs_quota_stat fqs;
 205
 206                         if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
 207                                 return ret;
 208                         if (copy_to_user(addr, &fqs, sizeof(fqs)))
 209                                 return -EFAULT;
 210                         return 0;
 211                 }
 212                 case Q_XSETQLIM: {
 213                         struct fs_disk_quota fdq;
 214
 215                         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 216                                 return -EFAULT;
 217                        return sb->s_qcop->set_xquota(sb, type, id, &fdq);
 218                 }
 219                 case Q_XGETQUOTA: {
 220                         struct fs_disk_quota fdq;
 221
 222                         if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq)))
 223                                 return ret;
 224                         if (copy_to_user(addr, &fdq, sizeof(fdq)))
 225                                 return -EFAULT;
 226                         return 0;
 227                 }
 228                 /* We never reach here unless validity check is broken */
 229                 default:
 230                         BUG();
 231         }
 232         return 0;
 233 }
 234
 235 /*
 236  * This is the system call interface. This communicates with
 237  * the user-level programs. Currently this only supports diskquota
 238  * calls. Maybe we need to add the process quotas etc. in the future,
 239  * but we probably should use rlimits for that.
 240  */
 241 asmlinkage long sys_quotactl(unsigned int cmd, const char *special, qid_t id, caddr_t addr)
 242 {
 243         uint cmds, type;
 244         struct super_block *sb = NULL;
 245         int ret = -EINVAL;
 246
 247         lock_kernel();
 248         cmds = cmd >> SUBCMDSHIFT;
 249         type = cmd & SUBCMDMASK;
 250
 251         if (IS_ERR(sb = resolve_dev(special))) {
 252                 ret = PTR_ERR(sb);
 253                 sb = NULL;
 254                 goto out;
 255         }
 256         if ((ret = check_quotactl_valid(sb, type, cmds, id)) < 0)
 257                 goto out;
 258         ret = do_quotactl(sb, type, cmds, id, addr);
 259 out:
 260         if (sb)
 261                 drop_super(sb);
 262         unlock_kernel();
 263         return ret;
 264 }