Revision 99f857db8857aff691c51302f93648263ed07eb1 authored by David Woodhouse on 10 January 2013, 14:31:59 UTC, committed by H. Peter Anvin on 28 January 2013, 04:19:37 UTC
We have historically hard-coded entry points in head.S just so it's easy
to build the executable/bzImage headers with references to them.

Unfortunately, this leads to boot loaders abusing these "known" addresses
even when they are *explicitly* told that they "should look at the ELF
header to find this address, as it may change in the future". And even
when the address in question *has* actually been changed in the past,
without fanfare or thought to compatibility.

Thus we have bootloaders doing stunningly broken things like jumping
to offset 0x200 in the kernel startup code in 64-bit mode, *hoping*
that startup_64 is still there (it has moved at least once
before). And hoping that it's actually a 64-bit kernel despite the
fact that we don't give them any indication of that fact.

This patch should hopefully remove the temptation to abuse internal
addresses in future, where sternly worded comments have not sufficed.
Instead of having hard-coded addresses and saying "please don't abuse
these", we actually pull the addresses out of the ELF payload into
zoffset.h, and make build.c shove them back into the right places in
the bzImage header.

Rather than including zoffset.h into build.c and thus having to rebuild
the tool for every kernel build, we parse it instead. The parsing code
is small and simple.

This patch doesn't actually move any of the interesting entry points, so
any offending bootloader will still continue to "work" after this patch
is applied. For some version of "work" which includes jumping into the
compressed payload and crashing, if the bzImage it's given is a 32-bit
kernel. No change there then.

[ hpa: some of the issues in the description are addressed or
  retconned by the 2.12 boot protocol.  This patch has been edited to
  only remove fixed addresses that were *not* thus retconned. ]

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Link: http://lkml.kernel.org/r/1358513837.2397.247.camel@shinybook.infradead.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Matt Fleming <matt.fleming@intel.com>
1 parent b607e21
Raw File
scsi_ioctl.c
/*
 * Copyright (C) 2001 Jens Axboe <axboe@suse.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public Licens
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
 *
 */
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/capability.h>
#include <linux/completion.h>
#include <linux/cdrom.h>
#include <linux/ratelimit.h>
#include <linux/slab.h>
#include <linux/times.h>
#include <asm/uaccess.h>

#include <scsi/scsi.h>
#include <scsi/scsi_ioctl.h>
#include <scsi/scsi_cmnd.h>

struct blk_cmd_filter {
	unsigned long read_ok[BLK_SCSI_CMD_PER_LONG];
	unsigned long write_ok[BLK_SCSI_CMD_PER_LONG];
};

static struct blk_cmd_filter blk_default_cmd_filter;

/* Command group 3 is reserved and should never be used.  */
const unsigned char scsi_command_size_tbl[8] =
{
	6, 10, 10, 12,
	16, 12, 10, 10
};
EXPORT_SYMBOL(scsi_command_size_tbl);

#include <scsi/sg.h>

static int sg_get_version(int __user *p)
{
	static const int sg_version_num = 30527;
	return put_user(sg_version_num, p);
}

static int scsi_get_idlun(struct request_queue *q, int __user *p)
{
	return put_user(0, p);
}

static int scsi_get_bus(struct request_queue *q, int __user *p)
{
	return put_user(0, p);
}

static int sg_get_timeout(struct request_queue *q)
{
	return jiffies_to_clock_t(q->sg_timeout);
}

static int sg_set_timeout(struct request_queue *q, int __user *p)
{
	int timeout, err = get_user(timeout, p);

	if (!err)
		q->sg_timeout = clock_t_to_jiffies(timeout);

	return err;
}

static int sg_get_reserved_size(struct request_queue *q, int __user *p)
{
	unsigned val = min(q->sg_reserved_size, queue_max_sectors(q) << 9);

	return put_user(val, p);
}

static int sg_set_reserved_size(struct request_queue *q, int __user *p)
{
	int size, err = get_user(size, p);

	if (err)
		return err;

	if (size < 0)
		return -EINVAL;
	if (size > (queue_max_sectors(q) << 9))
		size = queue_max_sectors(q) << 9;

	q->sg_reserved_size = size;
	return 0;
}

/*
 * will always return that we are ATAPI even for a real SCSI drive, I'm not
 * so sure this is worth doing anything about (why would you care??)
 */
static int sg_emulated_host(struct request_queue *q, int __user *p)
{
	return put_user(1, p);
}

static void blk_set_cmd_filter_defaults(struct blk_cmd_filter *filter)
{
	/* Basic read-only commands */
	__set_bit(TEST_UNIT_READY, filter->read_ok);
	__set_bit(REQUEST_SENSE, filter->read_ok);
	__set_bit(READ_6, filter->read_ok);
	__set_bit(READ_10, filter->read_ok);
	__set_bit(READ_12, filter->read_ok);
	__set_bit(READ_16, filter->read_ok);
	__set_bit(READ_BUFFER, filter->read_ok);
	__set_bit(READ_DEFECT_DATA, filter->read_ok);
	__set_bit(READ_CAPACITY, filter->read_ok);
	__set_bit(READ_LONG, filter->read_ok);
	__set_bit(INQUIRY, filter->read_ok);
	__set_bit(MODE_SENSE, filter->read_ok);
	__set_bit(MODE_SENSE_10, filter->read_ok);
	__set_bit(LOG_SENSE, filter->read_ok);
	__set_bit(START_STOP, filter->read_ok);
	__set_bit(GPCMD_VERIFY_10, filter->read_ok);
	__set_bit(VERIFY_16, filter->read_ok);
	__set_bit(REPORT_LUNS, filter->read_ok);
	__set_bit(SERVICE_ACTION_IN, filter->read_ok);
	__set_bit(RECEIVE_DIAGNOSTIC, filter->read_ok);
	__set_bit(MAINTENANCE_IN, filter->read_ok);
	__set_bit(GPCMD_READ_BUFFER_CAPACITY, filter->read_ok);

	/* Audio CD commands */
	__set_bit(GPCMD_PLAY_CD, filter->read_ok);
	__set_bit(GPCMD_PLAY_AUDIO_10, filter->read_ok);
	__set_bit(GPCMD_PLAY_AUDIO_MSF, filter->read_ok);
	__set_bit(GPCMD_PLAY_AUDIO_TI, filter->read_ok);
	__set_bit(GPCMD_PAUSE_RESUME, filter->read_ok);

	/* CD/DVD data reading */
	__set_bit(GPCMD_READ_CD, filter->read_ok);
	__set_bit(GPCMD_READ_CD_MSF, filter->read_ok);
	__set_bit(GPCMD_READ_DISC_INFO, filter->read_ok);
	__set_bit(GPCMD_READ_CDVD_CAPACITY, filter->read_ok);
	__set_bit(GPCMD_READ_DVD_STRUCTURE, filter->read_ok);
	__set_bit(GPCMD_READ_HEADER, filter->read_ok);
	__set_bit(GPCMD_READ_TRACK_RZONE_INFO, filter->read_ok);
	__set_bit(GPCMD_READ_SUBCHANNEL, filter->read_ok);
	__set_bit(GPCMD_READ_TOC_PMA_ATIP, filter->read_ok);
	__set_bit(GPCMD_REPORT_KEY, filter->read_ok);
	__set_bit(GPCMD_SCAN, filter->read_ok);
	__set_bit(GPCMD_GET_CONFIGURATION, filter->read_ok);
	__set_bit(GPCMD_READ_FORMAT_CAPACITIES, filter->read_ok);
	__set_bit(GPCMD_GET_EVENT_STATUS_NOTIFICATION, filter->read_ok);
	__set_bit(GPCMD_GET_PERFORMANCE, filter->read_ok);
	__set_bit(GPCMD_SEEK, filter->read_ok);
	__set_bit(GPCMD_STOP_PLAY_SCAN, filter->read_ok);

	/* Basic writing commands */
	__set_bit(WRITE_6, filter->write_ok);
	__set_bit(WRITE_10, filter->write_ok);
	__set_bit(WRITE_VERIFY, filter->write_ok);
	__set_bit(WRITE_12, filter->write_ok);
	__set_bit(WRITE_VERIFY_12, filter->write_ok);
	__set_bit(WRITE_16, filter->write_ok);
	__set_bit(WRITE_LONG, filter->write_ok);
	__set_bit(WRITE_LONG_2, filter->write_ok);
	__set_bit(ERASE, filter->write_ok);
	__set_bit(GPCMD_MODE_SELECT_10, filter->write_ok);
	__set_bit(MODE_SELECT, filter->write_ok);
	__set_bit(LOG_SELECT, filter->write_ok);
	__set_bit(GPCMD_BLANK, filter->write_ok);
	__set_bit(GPCMD_CLOSE_TRACK, filter->write_ok);
	__set_bit(GPCMD_FLUSH_CACHE, filter->write_ok);
	__set_bit(GPCMD_FORMAT_UNIT, filter->write_ok);
	__set_bit(GPCMD_REPAIR_RZONE_TRACK, filter->write_ok);
	__set_bit(GPCMD_RESERVE_RZONE_TRACK, filter->write_ok);
	__set_bit(GPCMD_SEND_DVD_STRUCTURE, filter->write_ok);
	__set_bit(GPCMD_SEND_EVENT, filter->write_ok);
	__set_bit(GPCMD_SEND_KEY, filter->write_ok);
	__set_bit(GPCMD_SEND_OPC, filter->write_ok);
	__set_bit(GPCMD_SEND_CUE_SHEET, filter->write_ok);
	__set_bit(GPCMD_SET_SPEED, filter->write_ok);
	__set_bit(GPCMD_PREVENT_ALLOW_MEDIUM_REMOVAL, filter->write_ok);
	__set_bit(GPCMD_LOAD_UNLOAD, filter->write_ok);
	__set_bit(GPCMD_SET_STREAMING, filter->write_ok);
	__set_bit(GPCMD_SET_READ_AHEAD, filter->write_ok);
}

int blk_verify_command(unsigned char *cmd, fmode_t has_write_perm)
{
	struct blk_cmd_filter *filter = &blk_default_cmd_filter;

	/* root can do any command. */
	if (capable(CAP_SYS_RAWIO))
		return 0;

	/* if there's no filter set, assume we're filtering everything out */
	if (!filter)
		return -EPERM;

	/* Anybody who can open the device can do a read-safe command */
	if (test_bit(cmd[0], filter->read_ok))
		return 0;

	/* Write-safe commands require a writable open */
	if (test_bit(cmd[0], filter->write_ok) && has_write_perm)
		return 0;

	return -EPERM;
}
EXPORT_SYMBOL(blk_verify_command);

static int blk_fill_sghdr_rq(struct request_queue *q, struct request *rq,
			     struct sg_io_hdr *hdr, fmode_t mode)
{
	if (copy_from_user(rq->cmd, hdr->cmdp, hdr->cmd_len))
		return -EFAULT;
	if (blk_verify_command(rq->cmd, mode & FMODE_WRITE))
		return -EPERM;

	/*
	 * fill in request structure
	 */
	rq->cmd_len = hdr->cmd_len;
	rq->cmd_type = REQ_TYPE_BLOCK_PC;

	rq->timeout = msecs_to_jiffies(hdr->timeout);
	if (!rq->timeout)
		rq->timeout = q->sg_timeout;
	if (!rq->timeout)
		rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
	if (rq->timeout < BLK_MIN_SG_TIMEOUT)
		rq->timeout = BLK_MIN_SG_TIMEOUT;

	return 0;
}

static int blk_complete_sghdr_rq(struct request *rq, struct sg_io_hdr *hdr,
				 struct bio *bio)
{
	int r, ret = 0;

	/*
	 * fill in all the output members
	 */
	hdr->status = rq->errors & 0xff;
	hdr->masked_status = status_byte(rq->errors);
	hdr->msg_status = msg_byte(rq->errors);
	hdr->host_status = host_byte(rq->errors);
	hdr->driver_status = driver_byte(rq->errors);
	hdr->info = 0;
	if (hdr->masked_status || hdr->host_status || hdr->driver_status)
		hdr->info |= SG_INFO_CHECK;
	hdr->resid = rq->resid_len;
	hdr->sb_len_wr = 0;

	if (rq->sense_len && hdr->sbp) {
		int len = min((unsigned int) hdr->mx_sb_len, rq->sense_len);

		if (!copy_to_user(hdr->sbp, rq->sense, len))
			hdr->sb_len_wr = len;
		else
			ret = -EFAULT;
	}

	r = blk_rq_unmap_user(bio);
	if (!ret)
		ret = r;
	blk_put_request(rq);

	return ret;
}

static int sg_io(struct request_queue *q, struct gendisk *bd_disk,
		struct sg_io_hdr *hdr, fmode_t mode)
{
	unsigned long start_time;
	int writing = 0, ret = 0;
	struct request *rq;
	char sense[SCSI_SENSE_BUFFERSIZE];
	struct bio *bio;

	if (hdr->interface_id != 'S')
		return -EINVAL;
	if (hdr->cmd_len > BLK_MAX_CDB)
		return -EINVAL;

	if (hdr->dxfer_len > (queue_max_hw_sectors(q) << 9))
		return -EIO;

	if (hdr->dxfer_len)
		switch (hdr->dxfer_direction) {
		default:
			return -EINVAL;
		case SG_DXFER_TO_DEV:
			writing = 1;
			break;
		case SG_DXFER_TO_FROM_DEV:
		case SG_DXFER_FROM_DEV:
			break;
		}

	rq = blk_get_request(q, writing ? WRITE : READ, GFP_KERNEL);
	if (!rq)
		return -ENOMEM;

	if (blk_fill_sghdr_rq(q, rq, hdr, mode)) {
		blk_put_request(rq);
		return -EFAULT;
	}

	if (hdr->iovec_count) {
		const int size = sizeof(struct sg_iovec) * hdr->iovec_count;
		size_t iov_data_len;
		struct sg_iovec *sg_iov;
		struct iovec *iov;
		int i;

		sg_iov = kmalloc(size, GFP_KERNEL);
		if (!sg_iov) {
			ret = -ENOMEM;
			goto out;
		}

		if (copy_from_user(sg_iov, hdr->dxferp, size)) {
			kfree(sg_iov);
			ret = -EFAULT;
			goto out;
		}

		/*
		 * Sum up the vecs, making sure they don't overflow
		 */
		iov = (struct iovec *) sg_iov;
		iov_data_len = 0;
		for (i = 0; i < hdr->iovec_count; i++) {
			if (iov_data_len + iov[i].iov_len < iov_data_len) {
				kfree(sg_iov);
				ret = -EINVAL;
				goto out;
			}
			iov_data_len += iov[i].iov_len;
		}

		/* SG_IO howto says that the shorter of the two wins */
		if (hdr->dxfer_len < iov_data_len) {
			hdr->iovec_count = iov_shorten(iov,
						       hdr->iovec_count,
						       hdr->dxfer_len);
			iov_data_len = hdr->dxfer_len;
		}

		ret = blk_rq_map_user_iov(q, rq, NULL, sg_iov, hdr->iovec_count,
					  iov_data_len, GFP_KERNEL);
		kfree(sg_iov);
	} else if (hdr->dxfer_len)
		ret = blk_rq_map_user(q, rq, NULL, hdr->dxferp, hdr->dxfer_len,
				      GFP_KERNEL);

	if (ret)
		goto out;

	bio = rq->bio;
	memset(sense, 0, sizeof(sense));
	rq->sense = sense;
	rq->sense_len = 0;
	rq->retries = 0;

	start_time = jiffies;

	/* ignore return value. All information is passed back to caller
	 * (if he doesn't check that is his problem).
	 * N.B. a non-zero SCSI status is _not_ necessarily an error.
	 */
	blk_execute_rq(q, bd_disk, rq, 0);

	hdr->duration = jiffies_to_msecs(jiffies - start_time);

	return blk_complete_sghdr_rq(rq, hdr, bio);
out:
	blk_put_request(rq);
	return ret;
}

/**
 * sg_scsi_ioctl  --  handle deprecated SCSI_IOCTL_SEND_COMMAND ioctl
 * @file:	file this ioctl operates on (optional)
 * @q:		request queue to send scsi commands down
 * @disk:	gendisk to operate on (option)
 * @sic:	userspace structure describing the command to perform
 *
 * Send down the scsi command described by @sic to the device below
 * the request queue @q.  If @file is non-NULL it's used to perform
 * fine-grained permission checks that allow users to send down
 * non-destructive SCSI commands.  If the caller has a struct gendisk
 * available it should be passed in as @disk to allow the low level
 * driver to use the information contained in it.  A non-NULL @disk
 * is only allowed if the caller knows that the low level driver doesn't
 * need it (e.g. in the scsi subsystem).
 *
 * Notes:
 *   -  This interface is deprecated - users should use the SG_IO
 *      interface instead, as this is a more flexible approach to
 *      performing SCSI commands on a device.
 *   -  The SCSI command length is determined by examining the 1st byte
 *      of the given command. There is no way to override this.
 *   -  Data transfers are limited to PAGE_SIZE
 *   -  The length (x + y) must be at least OMAX_SB_LEN bytes long to
 *      accommodate the sense buffer when an error occurs.
 *      The sense buffer is truncated to OMAX_SB_LEN (16) bytes so that
 *      old code will not be surprised.
 *   -  If a Unix error occurs (e.g. ENOMEM) then the user will receive
 *      a negative return and the Unix error code in 'errno'.
 *      If the SCSI command succeeds then 0 is returned.
 *      Positive numbers returned are the compacted SCSI error codes (4
 *      bytes in one int) where the lowest byte is the SCSI status.
 */
#define OMAX_SB_LEN 16          /* For backward compatibility */
int sg_scsi_ioctl(struct request_queue *q, struct gendisk *disk, fmode_t mode,
		struct scsi_ioctl_command __user *sic)
{
	struct request *rq;
	int err;
	unsigned int in_len, out_len, bytes, opcode, cmdlen;
	char *buffer = NULL, sense[SCSI_SENSE_BUFFERSIZE];

	if (!sic)
		return -EINVAL;

	/*
	 * get in an out lengths, verify they don't exceed a page worth of data
	 */
	if (get_user(in_len, &sic->inlen))
		return -EFAULT;
	if (get_user(out_len, &sic->outlen))
		return -EFAULT;
	if (in_len > PAGE_SIZE || out_len > PAGE_SIZE)
		return -EINVAL;
	if (get_user(opcode, sic->data))
		return -EFAULT;

	bytes = max(in_len, out_len);
	if (bytes) {
		buffer = kzalloc(bytes, q->bounce_gfp | GFP_USER| __GFP_NOWARN);
		if (!buffer)
			return -ENOMEM;

	}

	rq = blk_get_request(q, in_len ? WRITE : READ, __GFP_WAIT);

	cmdlen = COMMAND_SIZE(opcode);

	/*
	 * get command and data to send to device, if any
	 */
	err = -EFAULT;
	rq->cmd_len = cmdlen;
	if (copy_from_user(rq->cmd, sic->data, cmdlen))
		goto error;

	if (in_len && copy_from_user(buffer, sic->data + cmdlen, in_len))
		goto error;

	err = blk_verify_command(rq->cmd, mode & FMODE_WRITE);
	if (err)
		goto error;

	/* default.  possible overriden later */
	rq->retries = 5;

	switch (opcode) {
	case SEND_DIAGNOSTIC:
	case FORMAT_UNIT:
		rq->timeout = FORMAT_UNIT_TIMEOUT;
		rq->retries = 1;
		break;
	case START_STOP:
		rq->timeout = START_STOP_TIMEOUT;
		break;
	case MOVE_MEDIUM:
		rq->timeout = MOVE_MEDIUM_TIMEOUT;
		break;
	case READ_ELEMENT_STATUS:
		rq->timeout = READ_ELEMENT_STATUS_TIMEOUT;
		break;
	case READ_DEFECT_DATA:
		rq->timeout = READ_DEFECT_DATA_TIMEOUT;
		rq->retries = 1;
		break;
	default:
		rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
		break;
	}

	if (bytes && blk_rq_map_kern(q, rq, buffer, bytes, __GFP_WAIT)) {
		err = DRIVER_ERROR << 24;
		goto out;
	}

	memset(sense, 0, sizeof(sense));
	rq->sense = sense;
	rq->sense_len = 0;
	rq->cmd_type = REQ_TYPE_BLOCK_PC;

	blk_execute_rq(q, disk, rq, 0);

out:
	err = rq->errors & 0xff;	/* only 8 bit SCSI status */
	if (err) {
		if (rq->sense_len && rq->sense) {
			bytes = (OMAX_SB_LEN > rq->sense_len) ?
				rq->sense_len : OMAX_SB_LEN;
			if (copy_to_user(sic->data, rq->sense, bytes))
				err = -EFAULT;
		}
	} else {
		if (copy_to_user(sic->data, buffer, out_len))
			err = -EFAULT;
	}
	
error:
	kfree(buffer);
	blk_put_request(rq);
	return err;
}
EXPORT_SYMBOL_GPL(sg_scsi_ioctl);

/* Send basic block requests */
static int __blk_send_generic(struct request_queue *q, struct gendisk *bd_disk,
			      int cmd, int data)
{
	struct request *rq;
	int err;

	rq = blk_get_request(q, WRITE, __GFP_WAIT);
	rq->cmd_type = REQ_TYPE_BLOCK_PC;
	rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
	rq->cmd[0] = cmd;
	rq->cmd[4] = data;
	rq->cmd_len = 6;
	err = blk_execute_rq(q, bd_disk, rq, 0);
	blk_put_request(rq);

	return err;
}

static inline int blk_send_start_stop(struct request_queue *q,
				      struct gendisk *bd_disk, int data)
{
	return __blk_send_generic(q, bd_disk, GPCMD_START_STOP_UNIT, data);
}

int scsi_cmd_ioctl(struct request_queue *q, struct gendisk *bd_disk, fmode_t mode,
		   unsigned int cmd, void __user *arg)
{
	int err;

	if (!q)
		return -ENXIO;

	switch (cmd) {
		/*
		 * new sgv3 interface
		 */
		case SG_GET_VERSION_NUM:
			err = sg_get_version(arg);
			break;
		case SCSI_IOCTL_GET_IDLUN:
			err = scsi_get_idlun(q, arg);
			break;
		case SCSI_IOCTL_GET_BUS_NUMBER:
			err = scsi_get_bus(q, arg);
			break;
		case SG_SET_TIMEOUT:
			err = sg_set_timeout(q, arg);
			break;
		case SG_GET_TIMEOUT:
			err = sg_get_timeout(q);
			break;
		case SG_GET_RESERVED_SIZE:
			err = sg_get_reserved_size(q, arg);
			break;
		case SG_SET_RESERVED_SIZE:
			err = sg_set_reserved_size(q, arg);
			break;
		case SG_EMULATED_HOST:
			err = sg_emulated_host(q, arg);
			break;
		case SG_IO: {
			struct sg_io_hdr hdr;

			err = -EFAULT;
			if (copy_from_user(&hdr, arg, sizeof(hdr)))
				break;
			err = sg_io(q, bd_disk, &hdr, mode);
			if (err == -EFAULT)
				break;

			if (copy_to_user(arg, &hdr, sizeof(hdr)))
				err = -EFAULT;
			break;
		}
		case CDROM_SEND_PACKET: {
			struct cdrom_generic_command cgc;
			struct sg_io_hdr hdr;

			err = -EFAULT;
			if (copy_from_user(&cgc, arg, sizeof(cgc)))
				break;
			cgc.timeout = clock_t_to_jiffies(cgc.timeout);
			memset(&hdr, 0, sizeof(hdr));
			hdr.interface_id = 'S';
			hdr.cmd_len = sizeof(cgc.cmd);
			hdr.dxfer_len = cgc.buflen;
			err = 0;
			switch (cgc.data_direction) {
				case CGC_DATA_UNKNOWN:
					hdr.dxfer_direction = SG_DXFER_UNKNOWN;
					break;
				case CGC_DATA_WRITE:
					hdr.dxfer_direction = SG_DXFER_TO_DEV;
					break;
				case CGC_DATA_READ:
					hdr.dxfer_direction = SG_DXFER_FROM_DEV;
					break;
				case CGC_DATA_NONE:
					hdr.dxfer_direction = SG_DXFER_NONE;
					break;
				default:
					err = -EINVAL;
			}
			if (err)
				break;

			hdr.dxferp = cgc.buffer;
			hdr.sbp = cgc.sense;
			if (hdr.sbp)
				hdr.mx_sb_len = sizeof(struct request_sense);
			hdr.timeout = jiffies_to_msecs(cgc.timeout);
			hdr.cmdp = ((struct cdrom_generic_command __user*) arg)->cmd;
			hdr.cmd_len = sizeof(cgc.cmd);

			err = sg_io(q, bd_disk, &hdr, mode);
			if (err == -EFAULT)
				break;

			if (hdr.status)
				err = -EIO;

			cgc.stat = err;
			cgc.buflen = hdr.resid;
			if (copy_to_user(arg, &cgc, sizeof(cgc)))
				err = -EFAULT;

			break;
		}

		/*
		 * old junk scsi send command ioctl
		 */
		case SCSI_IOCTL_SEND_COMMAND:
			printk(KERN_WARNING "program %s is using a deprecated SCSI ioctl, please convert it to SG_IO\n", current->comm);
			err = -EINVAL;
			if (!arg)
				break;

			err = sg_scsi_ioctl(q, bd_disk, mode, arg);
			break;
		case CDROMCLOSETRAY:
			err = blk_send_start_stop(q, bd_disk, 0x03);
			break;
		case CDROMEJECT:
			err = blk_send_start_stop(q, bd_disk, 0x02);
			break;
		default:
			err = -ENOTTY;
	}

	return err;
}
EXPORT_SYMBOL(scsi_cmd_ioctl);

int scsi_verify_blk_ioctl(struct block_device *bd, unsigned int cmd)
{
	if (bd && bd == bd->bd_contains)
		return 0;

	/* Actually none of these is particularly useful on a partition,
	 * but they are safe.
	 */
	switch (cmd) {
	case SCSI_IOCTL_GET_IDLUN:
	case SCSI_IOCTL_GET_BUS_NUMBER:
	case SCSI_IOCTL_GET_PCI:
	case SCSI_IOCTL_PROBE_HOST:
	case SG_GET_VERSION_NUM:
	case SG_SET_TIMEOUT:
	case SG_GET_TIMEOUT:
	case SG_GET_RESERVED_SIZE:
	case SG_SET_RESERVED_SIZE:
	case SG_EMULATED_HOST:
		return 0;
	case CDROM_GET_CAPABILITY:
		/* Keep this until we remove the printk below.  udev sends it
		 * and we do not want to spam dmesg about it.   CD-ROMs do
		 * not have partitions, so we get here only for disks.
		 */
		return -ENOIOCTLCMD;
	default:
		break;
	}

	if (capable(CAP_SYS_RAWIO))
		return 0;

	/* In particular, rule out all resets and host-specific ioctls.  */
	printk_ratelimited(KERN_WARNING
			   "%s: sending ioctl %x to a partition!\n", current->comm, cmd);

	return -ENOIOCTLCMD;
}
EXPORT_SYMBOL(scsi_verify_blk_ioctl);

int scsi_cmd_blk_ioctl(struct block_device *bd, fmode_t mode,
		       unsigned int cmd, void __user *arg)
{
	int ret;

	ret = scsi_verify_blk_ioctl(bd, cmd);
	if (ret < 0)
		return ret;

	return scsi_cmd_ioctl(bd->bd_disk->queue, bd->bd_disk, mode, cmd, arg);
}
EXPORT_SYMBOL(scsi_cmd_blk_ioctl);

static int __init blk_scsi_ioctl_init(void)
{
	blk_set_cmd_filter_defaults(&blk_default_cmd_filter);
	return 0;
}
fs_initcall(blk_scsi_ioctl_init);
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