/*
 * 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_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)
{
        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_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_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_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;
}