/*
   * Quota code necessary even when VFS quota support is not compiled
   * into the kernel.  The interesting stuff is over in dquot.c, here
   * we have symbols for initial quotactl(2) handling, the sysctl(2)
   * variables, etc - things needed even when quota support disabled.
   */
  
  #include <linux/fs.h>
  #include <linux/namei.h>
  #include <linux/slab.h>
  #include <asm/current.h>
  #include <linux/uaccess.h>
  #include <linux/kernel.h>
  #include <linux/security.h>
  #include <linux/syscalls.h>
  #include <linux/capability.h>
  #include <linux/quotaops.h>
  #include <linux/types.h>
  #include <linux/writeback.h>
  
  static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
  				     qid_t id)
  {
  	switch (cmd) {
  	/* these commands do not require any special privilegues */
  	case Q_GETFMT:
  	case Q_SYNC:
  	case Q_GETINFO:
  	case Q_XGETQSTAT:
  	case Q_XGETQSTATV:
  	case Q_XQUOTASYNC:
  		break;
  	/* allow to query information for dquots we "own" */
  	case Q_GETQUOTA:
  	case Q_XGETQUOTA:
  		if ((type == USRQUOTA && uid_eq(current_euid(), make_kuid(current_user_ns(), id))) ||
  		    (type == GRPQUOTA && in_egroup_p(make_kgid(current_user_ns(), id))))
  			break;
  		/*FALLTHROUGH*/
  	default:
  		if (!capable(CAP_SYS_ADMIN))
  			return -EPERM;
  	}
  
  	return security_quotactl(cmd, type, id, sb);
  }
  
  static void quota_sync_one(struct super_block *sb, void *arg)
  {
  	if (sb->s_qcop && sb->s_qcop->quota_sync)
  		sb->s_qcop->quota_sync(sb, *(int *)arg);
  }
  
  static int quota_sync_all(int type)
  {
  	int ret;
  
  	if (type >= MAXQUOTAS)
  		return -EINVAL;
  	ret = security_quotactl(Q_SYNC, type, 0, NULL);
  	if (!ret)
  		iterate_supers(quota_sync_one, &type);
  	return ret;
  }
  
  static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
  		         struct path *path)
  {
  	if (!sb->s_qcop->quota_on && !sb->s_qcop->quota_on_meta)
  		return -ENOSYS;
  	if (sb->s_qcop->quota_on_meta)
  		return sb->s_qcop->quota_on_meta(sb, type, id);
  	if (IS_ERR(path))
  		return PTR_ERR(path);
  	return sb->s_qcop->quota_on(sb, type, id, path);
  }
  
  static int quota_getfmt(struct super_block *sb, int type, void __user *addr)
  {
  	__u32 fmt;
  
  	down_read(&sb_dqopt(sb)->dqptr_sem);
  	if (!sb_has_quota_active(sb, type)) {
  		up_read(&sb_dqopt(sb)->dqptr_sem);
  		return -ESRCH;
  	}
  	fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
  	up_read(&sb_dqopt(sb)->dqptr_sem);
  	if (copy_to_user(addr, &fmt, sizeof(fmt)))
  		return -EFAULT;
  	return 0;
  }
  
  static int quota_getinfo(struct super_block *sb, int type, void __user *addr)
  {
  	struct if_dqinfo info;
  	int ret;
  
  	if (!sb->s_qcop->get_info)
  		return -ENOSYS;
  	ret = sb->s_qcop->get_info(sb, type, &info);
  	if (!ret && copy_to_user(addr, &info, sizeof(info)))
  		return -EFAULT;
  	return ret;
  }
  
  static int quota_setinfo(struct super_block *sb, int type, void __user *addr)
  {
  	struct if_dqinfo info;
  
  	if (copy_from_user(&info, addr, sizeof(info)))
  		return -EFAULT;
  	if (!sb->s_qcop->set_info)
  		return -ENOSYS;
  	return sb->s_qcop->set_info(sb, type, &info);
  }
  
  static void copy_to_if_dqblk(struct if_dqblk *dst, struct fs_disk_quota *src)
  {
  	memset(dst, 0, sizeof(*dst));
  	dst->dqb_bhardlimit = src->d_blk_hardlimit;
  	dst->dqb_bsoftlimit = src->d_blk_softlimit;
  	dst->dqb_curspace = src->d_bcount;
  	dst->dqb_ihardlimit = src->d_ino_hardlimit;
  	dst->dqb_isoftlimit = src->d_ino_softlimit;
  	dst->dqb_curinodes = src->d_icount;
  	dst->dqb_btime = src->d_btimer;
  	dst->dqb_itime = src->d_itimer;
  	dst->dqb_valid = QIF_ALL;
  }
  
  static int quota_getquota(struct super_block *sb, int type, qid_t id,
  			  void __user *addr)
  {
  	struct kqid qid;
  	struct fs_disk_quota fdq;
  	struct if_dqblk idq;
  	int ret;
  
  	if (!sb->s_qcop->get_dqblk)
  		return -ENOSYS;
  	qid = make_kqid(current_user_ns(), type, id);
  	if (!qid_valid(qid))
  		return -EINVAL;
  	ret = sb->s_qcop->get_dqblk(sb, qid, &fdq);
  	if (ret)
  		return ret;
  	copy_to_if_dqblk(&idq, &fdq);
  	if (copy_to_user(addr, &idq, sizeof(idq)))
  		return -EFAULT;
  	return 0;
  }
  
  static void copy_from_if_dqblk(struct fs_disk_quota *dst, struct if_dqblk *src)
  {
  	dst->d_blk_hardlimit = src->dqb_bhardlimit;
  	dst->d_blk_softlimit  = src->dqb_bsoftlimit;
  	dst->d_bcount = src->dqb_curspace;
  	dst->d_ino_hardlimit = src->dqb_ihardlimit;
  	dst->d_ino_softlimit = src->dqb_isoftlimit;
  	dst->d_icount = src->dqb_curinodes;
  	dst->d_btimer = src->dqb_btime;
  	dst->d_itimer = src->dqb_itime;
  
  	dst->d_fieldmask = 0;
  	if (src->dqb_valid & QIF_BLIMITS)
  		dst->d_fieldmask |= FS_DQ_BSOFT | FS_DQ_BHARD;
  	if (src->dqb_valid & QIF_SPACE)
  		dst->d_fieldmask |= FS_DQ_BCOUNT;
  	if (src->dqb_valid & QIF_ILIMITS)
  		dst->d_fieldmask |= FS_DQ_ISOFT | FS_DQ_IHARD;
  	if (src->dqb_valid & QIF_INODES)
  		dst->d_fieldmask |= FS_DQ_ICOUNT;
  	if (src->dqb_valid & QIF_BTIME)
  		dst->d_fieldmask |= FS_DQ_BTIMER;
  	if (src->dqb_valid & QIF_ITIME)
  		dst->d_fieldmask |= FS_DQ_ITIMER;
  }
  
  static int quota_setquota(struct super_block *sb, int type, qid_t id,
  			  void __user *addr)
  {
  	struct fs_disk_quota fdq;
  	struct if_dqblk idq;
  	struct kqid qid;
  
  	if (copy_from_user(&idq, addr, sizeof(idq)))
  		return -EFAULT;
  	if (!sb->s_qcop->set_dqblk)
  		return -ENOSYS;
  	qid = make_kqid(current_user_ns(), type, id);
  	if (!qid_valid(qid))
  		return -EINVAL;
  	copy_from_if_dqblk(&fdq, &idq);
  	return sb->s_qcop->set_dqblk(sb, qid, &fdq);
  }
  
  static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
  {
  	__u32 flags;
  
  	if (copy_from_user(&flags, addr, sizeof(flags)))
  		return -EFAULT;
  	if (!sb->s_qcop->set_xstate)
  		return -ENOSYS;
  	return sb->s_qcop->set_xstate(sb, flags, cmd);
  }
  
  static int quota_getxstate(struct super_block *sb, void __user *addr)
  {
  	struct fs_quota_stat fqs;
  	int ret;
  
  	if (!sb->s_qcop->get_xstate)
  		return -ENOSYS;
  	ret = sb->s_qcop->get_xstate(sb, &fqs);
  	if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
  		return -EFAULT;
  	return ret;
  }
  
  static int quota_getxstatev(struct super_block *sb, void __user *addr)
  {
  	struct fs_quota_statv fqs;
  	int ret;
  
  	if (!sb->s_qcop->get_xstatev)
  		return -ENOSYS;
  
  	memset(&fqs, 0, sizeof(fqs));
  	if (copy_from_user(&fqs, addr, 1)) /* Just read qs_version */
  		return -EFAULT;
  
  	/* If this kernel doesn't support user specified version, fail */
  	switch (fqs.qs_version) {
  	case FS_QSTATV_VERSION1:
  		break;
  	default:
  		return -EINVAL;
  	}
  	ret = sb->s_qcop->get_xstatev(sb, &fqs);
  	if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
  		return -EFAULT;
  	return ret;
  }
  
  static int quota_setxquota(struct super_block *sb, int type, qid_t id,
  			   void __user *addr)
  {
  	struct fs_disk_quota fdq;
  	struct kqid qid;
  
  	if (copy_from_user(&fdq, addr, sizeof(fdq)))
  		return -EFAULT;
  	if (!sb->s_qcop->set_dqblk)
  		return -ENOSYS;
  	qid = make_kqid(current_user_ns(), type, id);
  	if (!qid_valid(qid))
  		return -EINVAL;
  	return sb->s_qcop->set_dqblk(sb, qid, &fdq);
  }
  
  static int quota_getxquota(struct super_block *sb, int type, qid_t id,
  			   void __user *addr)
  {
  	struct fs_disk_quota fdq;
  	struct kqid qid;
  	int ret;
  
  	if (!sb->s_qcop->get_dqblk)
  		return -ENOSYS;
  	qid = make_kqid(current_user_ns(), type, id);
  	if (!qid_valid(qid))
  		return -EINVAL;
  	ret = sb->s_qcop->get_dqblk(sb, qid, &fdq);
  	if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
  		return -EFAULT;
  	return ret;
  }
  
  /* Copy parameters and call proper function */
  static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
  		       void __user *addr, struct path *path)
  {
  	int ret;
  
  	if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
  		return -EINVAL;
  	if (!sb->s_qcop)
  		return -ENOSYS;
  
  	ret = check_quotactl_permission(sb, type, cmd, id);
  	if (ret < 0)
  		return ret;
  
  	switch (cmd) {
  	case Q_QUOTAON:
  		return quota_quotaon(sb, type, cmd, id, path);
  	case Q_QUOTAOFF:
  		if (!sb->s_qcop->quota_off)
  			return -ENOSYS;
  		return sb->s_qcop->quota_off(sb, type);
  	case Q_GETFMT:
  		return quota_getfmt(sb, type, addr);
  	case Q_GETINFO:
  		return quota_getinfo(sb, type, addr);
  	case Q_SETINFO:
  		return quota_setinfo(sb, type, addr);
  	case Q_GETQUOTA:
  		return quota_getquota(sb, type, id, addr);
  	case Q_SETQUOTA:
  		return quota_setquota(sb, type, id, addr);
  	case Q_SYNC:
  		if (!sb->s_qcop->quota_sync)
  			return -ENOSYS;
  		return sb->s_qcop->quota_sync(sb, type);
  	case Q_XQUOTAON:
  	case Q_XQUOTAOFF:
  	case Q_XQUOTARM:
  		return quota_setxstate(sb, cmd, addr);
  	case Q_XGETQSTAT:
  		return quota_getxstate(sb, addr);
  	case Q_XGETQSTATV:
  		return quota_getxstatev(sb, addr);
  	case Q_XSETQLIM:
  		return quota_setxquota(sb, type, id, addr);
  	case Q_XGETQUOTA:
  		return quota_getxquota(sb, type, id, addr);
  	case Q_XQUOTASYNC:
  		if (sb->s_flags & MS_RDONLY)
  			return -EROFS;
  		/* XFS quotas are fully coherent now, making this call a noop */
  		return 0;
  	default:
  		return -EINVAL;
  	}
  }
  
  #ifdef CONFIG_BLOCK
  
  /* Return 1 if 'cmd' will block on frozen filesystem */
  static int quotactl_cmd_write(int cmd)
  {
  	switch (cmd) {
  	case Q_GETFMT:
  	case Q_GETINFO:
  	case Q_SYNC:
  	case Q_XGETQSTAT:
  	case Q_XGETQSTATV:
  	case Q_XGETQUOTA:
  	case Q_XQUOTASYNC:
  		return 0;
  	}
  	return 1;
  }
  
  #endif /* CONFIG_BLOCK */
  
  /*
   * look up a superblock on which quota ops will be performed
   * - use the name of a block device to find the superblock thereon
   */
  static struct super_block *quotactl_block(const char __user *special, int cmd)
  {
  #ifdef CONFIG_BLOCK
  	struct block_device *bdev;
  	struct super_block *sb;
  	struct filename *tmp = getname(special);
  
  	if (IS_ERR(tmp))
  		return ERR_CAST(tmp);
  	bdev = lookup_bdev(tmp->name);
  	putname(tmp);
  	if (IS_ERR(bdev))
  		return ERR_CAST(bdev);
  	if (quotactl_cmd_write(cmd))
  		sb = get_super_thawed(bdev);
  	else
  		sb = get_super(bdev);
  	bdput(bdev);
  	if (!sb)
  		return ERR_PTR(-ENODEV);
  
  	return sb;
  #else
  	return ERR_PTR(-ENODEV);
  #endif
  }
  
  /*
   * This is the system call interface. This communicates with
   * the user-level programs. Currently this only supports diskquota
   * calls. Maybe we need to add the process quotas etc. in the future,
   * but we probably should use rlimits for that.
   */
  SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
  		qid_t, id, void __user *, addr)
  {
  	uint cmds, type;
  	struct super_block *sb = NULL;
  	struct path path, *pathp = NULL;
  	int ret;
  
  	cmds = cmd >> SUBCMDSHIFT;
  	type = cmd & SUBCMDMASK;
  
  	/*
  	 * As a special case Q_SYNC can be called without a specific device.
  	 * It will iterate all superblocks that have quota enabled and call
  	 * the sync action on each of them.
  	 */
  	if (!special) {
  		if (cmds == Q_SYNC)
  			return quota_sync_all(type);
  		return -ENODEV;
  	}
  
  	/*
  	 * Path for quotaon has to be resolved before grabbing superblock
  	 * because that gets s_umount sem which is also possibly needed by path
  	 * resolution (think about autofs) and thus deadlocks could arise.
  	 */
  	if (cmds == Q_QUOTAON) {
  		ret = user_path_at(AT_FDCWD, addr, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);
  		if (ret)
  			pathp = ERR_PTR(ret);
  		else
  			pathp = &path;
  	}
  
  	sb = quotactl_block(special, cmds);
  	if (IS_ERR(sb)) {
  		ret = PTR_ERR(sb);
  		goto out;
  	}
  
  	ret = do_quotactl(sb, type, cmds, id, addr, pathp);
  
  	drop_super(sb);
  out:
  	if (pathp && !IS_ERR(pathp))
  		path_put(pathp);
  	return ret;
  }