ioctl.c

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#include <linux/capability.h>
#include <linux/blkdev.h>
#include <linux/export.h>
#include <linux/gfp.h>
#include <linux/blkpg.h>
#include <linux/hdreg.h>
#include <linux/backing-dev.h>
#include <linux/fs.h>
#include <linux/blktrace_api.h>
#include <asm/uaccess.h>

static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user *arg)
{
    struct block_device *bdevp;
    struct gendisk *disk;
    struct hd_struct *part, *lpart;
    struct blkpg_ioctl_arg a;
    struct blkpg_partition p;
    struct disk_part_iter piter;
    long long start, length;
    int partno;

    if (!capable(CAP_SYS_ADMIN))
        return -EACCES;
    if (copy_from_user(&a, arg, sizeof(struct blkpg_ioctl_arg)))
        return -EFAULT;
    if (copy_from_user(&p, a.data, sizeof(struct blkpg_partition)))
        return -EFAULT;
    disk = bdev->bd_disk;
    if (bdev != bdev->bd_contains)
        return -EINVAL;
    partno = p.pno;
    if (partno <= 0)
        return -EINVAL;
    switch (a.op) {
        case BLKPG_ADD_PARTITION:
            start = p.start >> 9;
            length = p.length >> 9;
            /* check for fit in a hd_struct */
            if (sizeof(sector_t) == sizeof(long) &&
                sizeof(long long) > sizeof(long)) {
                long pstart = start, plength = length;
                if (pstart != start || plength != length
                    || pstart < 0 || plength < 0 || partno > 65535)
                    return -EINVAL;
            }

            mutex_lock(&bdev->bd_mutex);

            /* overlap? */
            disk_part_iter_init(&piter, disk,
                        DISK_PITER_INCL_EMPTY);
            while ((part = disk_part_iter_next(&piter))) {
                if (!(start + length <= part->start_sect ||
                      start >= part->start_sect + part->nr_sects)) {
                    disk_part_iter_exit(&piter);
                    mutex_unlock(&bdev->bd_mutex);
                    return -EBUSY;
                }
            }
            disk_part_iter_exit(&piter);

            /* all seems OK */
            part = add_partition(disk, partno, start, length,
                         ADDPART_FLAG_NONE, NULL);
            mutex_unlock(&bdev->bd_mutex);
            return IS_ERR(part) ? PTR_ERR(part) : 0;
        case BLKPG_DEL_PARTITION:
            part = disk_get_part(disk, partno);
            if (!part)
                return -ENXIO;

            bdevp = bdget(part_devt(part));
            disk_put_part(part);
            if (!bdevp)
                return -ENOMEM;

            mutex_lock(&bdevp->bd_mutex);
            if (bdevp->bd_openers) {
                mutex_unlock(&bdevp->bd_mutex);
                bdput(bdevp);
                return -EBUSY;
            }
            /* all seems OK */
            fsync_bdev(bdevp);
            invalidate_bdev(bdevp);

            mutex_lock_nested(&bdev->bd_mutex, 1);
            delete_partition(disk, partno);
            mutex_unlock(&bdev->bd_mutex);
            mutex_unlock(&bdevp->bd_mutex);
            bdput(bdevp);

            return 0;
        case BLKPG_RESIZE_PARTITION:
            start = p.start >> 9;
            /* new length of partition in bytes */
            length = p.length >> 9;
            /* check for fit in a hd_struct */
            if (sizeof(sector_t) == sizeof(long) &&
                sizeof(long long) > sizeof(long)) {
                long pstart = start, plength = length;
                if (pstart != start || plength != length
                    || pstart < 0 || plength < 0)
                    return -EINVAL;
            }
            part = disk_get_part(disk, partno);
            if (!part)
                return -ENXIO;
            bdevp = bdget(part_devt(part));
            if (!bdevp) {
                disk_put_part(part);
                return -ENOMEM;
            }
            mutex_lock(&bdevp->bd_mutex);
            mutex_lock_nested(&bdev->bd_mutex, 1);
            if (start != part->start_sect) {
                mutex_unlock(&bdevp->bd_mutex);
                mutex_unlock(&bdev->bd_mutex);
                bdput(bdevp);
                disk_put_part(part);
                return -EINVAL;
            }
            /* overlap? */
            disk_part_iter_init(&piter, disk,
                        DISK_PITER_INCL_EMPTY);
            while ((lpart = disk_part_iter_next(&piter))) {
                if (lpart->partno != partno &&
                   !(start + length <= lpart->start_sect ||
                   start >= lpart->start_sect + lpart->nr_sects)
                   ) {
                    disk_part_iter_exit(&piter);
                    mutex_unlock(&bdevp->bd_mutex);
                    mutex_unlock(&bdev->bd_mutex);
                    bdput(bdevp);
                    disk_put_part(part);
                    return -EBUSY;
                }
            }
            disk_part_iter_exit(&piter);
            part_nr_sects_write(part, (sector_t)length);
            i_size_write(bdevp->bd_inode, p.length);
            mutex_unlock(&bdevp->bd_mutex);
            mutex_unlock(&bdev->bd_mutex);
            bdput(bdevp);
            disk_put_part(part);
            return 0;
        default:
            return -EINVAL;
    }
}

static int blkdev_reread_part(struct block_device *bdev)
{
    struct gendisk *disk = bdev->bd_disk;
    int res;

    if (!disk_part_scan_enabled(disk) || bdev != bdev->bd_contains)
        return -EINVAL;
    if (!capable(CAP_SYS_ADMIN))
        return -EACCES;
    if (!mutex_trylock(&bdev->bd_mutex))
        return -EBUSY;
    res = rescan_partitions(disk, bdev);
    mutex_unlock(&bdev->bd_mutex);
    return res;
}

static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
                 uint64_t len, int secure)
{
    unsigned long flags = 0;

    if (start & 511)
        return -EINVAL;
    if (len & 511)
        return -EINVAL;
    start >>= 9;
    len >>= 9;

    if (start + len > (i_size_read(bdev->bd_inode) >> 9))
        return -EINVAL;
    if (secure)
        flags |= BLKDEV_DISCARD_SECURE;
    return blkdev_issue_discard(bdev, start, len, GFP_KERNEL, flags);
}

static int blk_ioctl_zeroout(struct block_device *bdev, uint64_t start,
                 uint64_t len)
{
    if (start & 511)
        return -EINVAL;
    if (len & 511)
        return -EINVAL;
    start >>= 9;
    len >>= 9;

    if (start + len > (i_size_read(bdev->bd_inode) >> 9))
        return -EINVAL;

    return blkdev_issue_zeroout(bdev, start, len, GFP_KERNEL);
}

static int put_ushort(unsigned long arg, unsigned short val)
{
    return put_user(val, (unsigned short __user *)arg);
}

static int put_int(unsigned long arg, int val)
{
    return put_user(val, (int __user *)arg);
}

static int put_uint(unsigned long arg, unsigned int val)
{
    return put_user(val, (unsigned int __user *)arg);
}

static int put_long(unsigned long arg, long val)
{
    return put_user(val, (long __user *)arg);
}

static int put_ulong(unsigned long arg, unsigned long val)
{
    return put_user(val, (unsigned long __user *)arg);
}

static int put_u64(unsigned long arg, u64 val)
{
    return put_user(val, (u64 __user *)arg);
}

int __blkdev_driver_ioctl(struct block_device *bdev, fmode_t mode,
            unsigned cmd, unsigned long arg)
{
    struct gendisk *disk = bdev->bd_disk;

    if (disk->fops->ioctl)
        return disk->fops->ioctl(bdev, mode, cmd, arg);

    return -ENOTTY;
}
/*
 * For the record: _GPL here is only because somebody decided to slap it
 * on the previous export.  Sheer idiocy, since it wasn't copyrightable
 * at all and could be open-coded without any exports by anybody who cares.
 */
EXPORT_SYMBOL_GPL(__blkdev_driver_ioctl);

/*
 * Is it an unrecognized ioctl? The correct returns are either
 * ENOTTY (final) or ENOIOCTLCMD ("I don't know this one, try a
 * fallback"). ENOIOCTLCMD gets turned into ENOTTY by the ioctl
 * code before returning.
 *
 * Confused drivers sometimes return EINVAL, which is wrong. It
 * means "I understood the ioctl command, but the parameters to
 * it were wrong".
 *
 * We should aim to just fix the broken drivers, the EINVAL case
 * should go away.
 */
static inline int is_unrecognized_ioctl(int ret)
{
    return  ret == -EINVAL ||
        ret == -ENOTTY ||
        ret == -ENOIOCTLCMD;
}

/*
 * always keep this in sync with compat_blkdev_ioctl()
 */
int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
            unsigned long arg)
{
    struct gendisk *disk = bdev->bd_disk;
    struct backing_dev_info *bdi;
    loff_t size;
    int ret, n;

    switch(cmd) {
    case BLKFLSBUF:
        if (!capable(CAP_SYS_ADMIN))
            return -EACCES;

        ret = __blkdev_driver_ioctl(bdev, mode, cmd, arg);
        if (!is_unrecognized_ioctl(ret))
            return ret;

        fsync_bdev(bdev);
        invalidate_bdev(bdev);
        return 0;

    case BLKROSET:
        ret = __blkdev_driver_ioctl(bdev, mode, cmd, arg);
        if (!is_unrecognized_ioctl(ret))
            return ret;
        if (!capable(CAP_SYS_ADMIN))
            return -EACCES;
        if (get_user(n, (int __user *)(arg)))
            return -EFAULT;
        set_device_ro(bdev, n);
        return 0;

    case BLKDISCARD:
    case BLKSECDISCARD: {
        uint64_t range[2];

        if (!(mode & FMODE_WRITE))
            return -EBADF;

        if (copy_from_user(range, (void __user *)arg, sizeof(range)))
            return -EFAULT;

        return blk_ioctl_discard(bdev, range[0], range[1],
                     cmd == BLKSECDISCARD);
    }
    case BLKZEROOUT: {
        uint64_t range[2];

        if (!(mode & FMODE_WRITE))
            return -EBADF;

        if (copy_from_user(range, (void __user *)arg, sizeof(range)))
            return -EFAULT;

        return blk_ioctl_zeroout(bdev, range[0], range[1]);
    }

    case HDIO_GETGEO: {
        struct hd_geometry geo;

        if (!arg)
            return -EINVAL;
        if (!disk->fops->getgeo)
            return -ENOTTY;

        /*
         * We need to set the startsect first, the driver may
         * want to override it.
         */
        memset(&geo, 0, sizeof(geo));
        geo.start = get_start_sect(bdev);
        ret = disk->fops->getgeo(bdev, &geo);
        if (ret)
            return ret;
        if (copy_to_user((struct hd_geometry __user *)arg, &geo,
                    sizeof(geo)))
            return -EFAULT;
        return 0;
    }
    case BLKRAGET:
    case BLKFRAGET:
        if (!arg)
            return -EINVAL;
        bdi = blk_get_backing_dev_info(bdev);
        if (bdi == NULL)
            return -ENOTTY;
        return put_long(arg, (bdi->ra_pages * PAGE_CACHE_SIZE) / 512);
    case BLKROGET:
        return put_int(arg, bdev_read_only(bdev) != 0);
    case BLKBSZGET: /* get block device soft block size (cf. BLKSSZGET) */
        return put_int(arg, block_size(bdev));
    case BLKSSZGET: /* get block device logical block size */
        return put_int(arg, bdev_logical_block_size(bdev));
    case BLKPBSZGET: /* get block device physical block size */
        return put_uint(arg, bdev_physical_block_size(bdev));
    case BLKIOMIN:
        return put_uint(arg, bdev_io_min(bdev));
    case BLKIOOPT:
        return put_uint(arg, bdev_io_opt(bdev));
    case BLKALIGNOFF:
        return put_int(arg, bdev_alignment_offset(bdev));
    case BLKDISCARDZEROES:
        return put_uint(arg, bdev_discard_zeroes_data(bdev));
    case BLKSECTGET:
        return put_ushort(arg, queue_max_sectors(bdev_get_queue(bdev)));
    case BLKROTATIONAL:
        return put_ushort(arg, !blk_queue_nonrot(bdev_get_queue(bdev)));
    case BLKRASET:
    case BLKFRASET:
        if(!capable(CAP_SYS_ADMIN))
            return -EACCES;
        bdi = blk_get_backing_dev_info(bdev);
        if (bdi == NULL)
            return -ENOTTY;
        bdi->ra_pages = (arg * 512) / PAGE_CACHE_SIZE;
        return 0;
    case BLKBSZSET:
        /* set the logical block size */
        if (!capable(CAP_SYS_ADMIN))
            return -EACCES;
        if (!arg)
            return -EINVAL;
        if (get_user(n, (int __user *) arg))
            return -EFAULT;
        if (!(mode & FMODE_EXCL)) {
            bdgrab(bdev);
            if (blkdev_get(bdev, mode | FMODE_EXCL, &bdev) < 0)
                return -EBUSY;
        }
        ret = set_blocksize(bdev, n);
        if (!(mode & FMODE_EXCL))
            blkdev_put(bdev, mode | FMODE_EXCL);
        return ret;
    case BLKPG:
        ret = blkpg_ioctl(bdev, (struct blkpg_ioctl_arg __user *) arg);
        break;
    case BLKRRPART:
        ret = blkdev_reread_part(bdev);
        break;
    case BLKGETSIZE:
        size = i_size_read(bdev->bd_inode);
        if ((size >> 9) > ~0UL)
            return -EFBIG;
        return put_ulong(arg, size >> 9);
    case BLKGETSIZE64:
        return put_u64(arg, i_size_read(bdev->bd_inode));
    case BLKTRACESTART:
    case BLKTRACESTOP:
    case BLKTRACESETUP:
    case BLKTRACETEARDOWN:
        ret = blk_trace_ioctl(bdev, cmd, (char __user *) arg);
        break;
    default:
        ret = __blkdev_driver_ioctl(bdev, mode, cmd, arg);
    }
    return ret;
}
EXPORT_SYMBOL_GPL(blkdev_ioctl);