[PATCH 0/3] block: add queue-private command filter, editable via sysfs

[PATCH 0/3] block: add queue-private command filter, editable via sysfs

[Paolo Bonzini]

The set of use cases for SG_IO is quite variable that no single filter can
accomodate all of them.  The current filter is tailored very much to
CD burning, and includes many MMC-specific commands that may have
other meanings in different standards.  Someone may want to remove
those commands; at the same time, people that trust their users may
want to add persistent reservations, trim/discard, or even access to
vendor-specific commands.

Filters used to be mutable via sysfs, but the implementation was
never enabled.  Add it back, and let the admin set this up per device.
The ideal is that we would be much more restrictive by default and
give root the ability to override this both globally and per-device.
But this piece of the policy should probably be implemented in userspace
for better backwards compatibility.

In the meanwhile, this patch series provides the sysfs knob.  It is a
tweaked revert of commit 018e044 (block: get rid of queue-private command
filter, 2009-06-26).

Paolo Bonzini (3):
  block: add back queue-private command filter
  scsi: create an all-zero filter for scanners
  block: add back command filter modification via sysfs

 Documentation/block/queue-sysfs.txt |   16 +++++
 block/Kconfig                       |   10 +++
 block/blk-sysfs.c                   |   43 +++++++++++++
 block/bsg.c                         |    2 +-
 block/scsi_ioctl.c                  |  117 +++++++++++++++++++++++++++++++----
 drivers/scsi/scsi_scan.c            |    6 ++-
 drivers/scsi/sg.c                   |    7 +-
 include/linux/blkdev.h              |   31 +++++++++-
 8 files changed, 213 insertions(+), 19 deletions(-)

[PATCH 1/3] block: add back queue-private command filter

[Paolo Bonzini]

The command filter used to be mutable via sysfs, but this was broken
and backed out.  Let's add it back.  This patch adds the infrastructure
for filtering, but unlike the old code this one just adds a pointer to
request_queue, so as to make it cheaper in the majority of cases where
no special filtering is desired.

This is a partial (and massaged) revert of commit 018e044 (block: get
rid of queue-private command filter, 2009-06-26).

Cc: linux-iscsi@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/blk-sysfs.c      |    2 ++
 block/bsg.c            |    2 +-
 block/scsi_ioctl.c     |   17 +++++------------
 drivers/scsi/sg.c      |    4 +++-
 include/linux/blkdev.h |   10 +++++++++-
 5 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 9628b29..5a0de07 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -487,6 +487,8 @@ static void blk_release_queue(struct kobject *kobj)
 
 	blkcg_exit_queue(q);
 
+	kfree(q->cmd_filter);
+
 	if (q->elevator) {
 		spin_lock_irq(q->queue_lock);
 		ioc_clear_queue(q);
diff --git a/block/bsg.c b/block/bsg.c
index ff64ae3..09956da 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -187,7 +187,7 @@ static int blk_fill_sgv4_hdr_rq(struct request_queue *q, struct request *rq,
 		return -EFAULT;
 
 	if (hdr->subprotocol == BSG_SUB_PROTOCOL_SCSI_CMD) {
-		if (blk_verify_command(rq->cmd, has_write_perm))
+		if (blk_verify_command(q->cmd_filter, rq->cmd, has_write_perm))
 			return -EPERM;
 	} else if (!capable(CAP_SYS_RAWIO))
 		return -EPERM;
diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index 9a87daa..c8862e9 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -33,11 +33,6 @@
 #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.  */
@@ -196,17 +191,15 @@ static void blk_set_cmd_filter_defaults(struct blk_cmd_filter *filter)
 	__set_bit(GPCMD_SET_READ_AHEAD, filter->write_ok);
 }
 
-int blk_verify_command(unsigned char *cmd, fmode_t has_write_perm)
+int blk_verify_command(struct blk_cmd_filter *filter,
+		       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;
+		filter = &blk_default_cmd_filter;
 
 	/* Anybody who can open the device can do a read-safe command */
 	if (test_bit(cmd[0], filter->read_ok))
@@ -225,7 +218,7 @@ static int blk_fill_sghdr_rq(struct request_queue *q, struct request *rq,
 {
 	if (copy_from_user(rq->cmd, hdr->cmdp, hdr->cmd_len))
 		return -EFAULT;
-	if (blk_verify_command(rq->cmd, mode & FMODE_WRITE))
+	if (blk_verify_command(q->cmd_filter, rq->cmd, mode & FMODE_WRITE))
 		return -EPERM;
 
 	/*
@@ -472,7 +465,7 @@ int sg_scsi_ioctl(struct request_queue *q, struct gendisk *disk, fmode_t mode,
 	if (in_len && copy_from_user(buffer, sic->data + cmdlen, in_len))
 		goto error;
 
-	err = blk_verify_command(rq->cmd, mode & FMODE_WRITE);
+	err = blk_verify_command(q->cmd_filter, rq->cmd, mode & FMODE_WRITE);
 	if (err)
 		goto error;
 
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 9c5c5f2..2ba7c82 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -217,11 +217,13 @@ static void sg_put_dev(Sg_device *sdp);
 static int sg_allow_access(struct file *filp, unsigned char *cmd)
 {
 	struct sg_fd *sfp = filp->private_data;
+	struct request_queue *q = sfp->parentdp->device->request_queue;
 
 	if (sfp->parentdp->device->type == TYPE_SCANNER)
 		return 0;
 
-	return blk_verify_command(cmd, filp->f_mode & FMODE_WRITE);
+	return blk_verify_command(q->cmd_filter,
+				  cmd, filp->f_mode & FMODE_WRITE);
 }
 
 static int get_exclude(Sg_device *sdp)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 4a2ab7c..b5c5f8a 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -258,6 +258,11 @@ struct blk_queue_tag {
 #define BLK_SCSI_MAX_CMDS	(256)
 #define BLK_SCSI_CMD_PER_LONG	(BLK_SCSI_MAX_CMDS / (sizeof(long) * 8))
 
+struct blk_cmd_filter {
+	unsigned long read_ok[BLK_SCSI_CMD_PER_LONG];
+	unsigned long write_ok[BLK_SCSI_CMD_PER_LONG];
+};
+
 struct queue_limits {
 	unsigned long		bounce_pfn;
 	unsigned long		seg_boundary_mask;
@@ -423,6 +428,8 @@ struct request_queue {
 	struct bsg_class_device bsg_dev;
 #endif
 
+	struct blk_cmd_filter	*cmd_filter;
+
 #ifdef CONFIG_BLK_CGROUP
 	struct list_head	all_q_node;
 #endif
@@ -1005,7 +1012,8 @@ static inline int sb_issue_zeroout(struct super_block *sb, sector_t block,
 				    gfp_mask);
 }
 
-extern int blk_verify_command(unsigned char *cmd, fmode_t has_write_perm);
+extern int blk_verify_command(struct blk_cmd_filter *filter,
+			      unsigned char *cmd, fmode_t has_write_perm);
 
 enum blk_default_limits {
 	BLK_MAX_SEGMENTS	= 128,
-- 
1.7.1

[PATCH 2/3] scsi: create an all-zero filter for scanners

[Paolo Bonzini]

Using /dev/sg for scanners is blocked from unprivileged users.  Reimplement
this using customizable command filters, so that the sysfs knobs will work
in this case too.

Cc: linux-iscsi@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 drivers/scsi/scsi_scan.c |    6 +++++-
 drivers/scsi/sg.c        |    3 ---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 56a9379..d168c15 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -773,13 +773,17 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
 	}
 
 	switch (sdev->type) {
+	case TYPE_SCANNER:
+		sdev->request_queue->cmd_filter =
+			kzalloc(sizeof(struct blk_cmd_filter), GFP_KERNEL);
+		/* fallthrough */
+
 	case TYPE_RBC:
 	case TYPE_TAPE:
 	case TYPE_DISK:
 	case TYPE_PRINTER:
 	case TYPE_MOD:
 	case TYPE_PROCESSOR:
-	case TYPE_SCANNER:
 	case TYPE_MEDIUM_CHANGER:
 	case TYPE_ENCLOSURE:
 	case TYPE_COMM:
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 2ba7c82..c7474f5 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -219,9 +219,6 @@ static int sg_allow_access(struct file *filp, unsigned char *cmd)
 	struct sg_fd *sfp = filp->private_data;
 	struct request_queue *q = sfp->parentdp->device->request_queue;
 
-	if (sfp->parentdp->device->type == TYPE_SCANNER)
-		return 0;
-
 	return blk_verify_command(q->cmd_filter,
 				  cmd, filp->f_mode & FMODE_WRITE);
 }
-- 
1.7.1

[PATCH 3/3] block: add back command filter modification via sysfs

[Paolo Bonzini]

This adds two new sysfs attributes to the queue kobject.  The attributes
allow reading and writing the whitelist of unprivileged commands.

This is again a bit different from what was removed in commit 018e044
(block: get rid of queue-private command filter, 2009-06-26), but the idea
is the same.  One difference is that it does not use a separate kobject.
Also, the supported sysfs syntax is a bit more expressive: it includes
ranges, the ability to replace all of the filter with a single command,
and does not force usage of hexadecimal.

Since the names are different, and the old ones were anyway never really
enabled, the different API is not a problem.

Cc: linux-iscsi@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 Documentation/block/queue-sysfs.txt |   16 ++++++
 block/Kconfig                       |   10 ++++
 block/blk-sysfs.c                   |   41 ++++++++++++++
 block/scsi_ioctl.c                  |  100 +++++++++++++++++++++++++++++++++++
 include/linux/blkdev.h              |   21 +++++++
 5 files changed, 188 insertions(+), 0 deletions(-)

diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt
index e54ac1d..1152b38 100644
--- a/Documentation/block/queue-sysfs.txt
+++ b/Documentation/block/queue-sysfs.txt
@@ -133,6 +133,22 @@ control of this block device to that new IO scheduler. Note that writing
 an IO scheduler name to this file will attempt to load that IO scheduler
 module, if it isn't already present in the system.
 
+sgio_read_filter (RW)
+---------------------
+When read, this file will display a list of SCSI commands (i.e. values of
+the first byte of a CDB) that are always available for unprivileged users
+(via /dev/bsg, /dev/sgNN, or ioctls such as SG_IO and CDROM_SEND_PACKET).
+When written, the list of commands will be modified.  By default it
+will be completely replaced; writing a string that begins with '+' will
+add new commands, and writing a string that begins with '-' will remove
+some commands.  Ranges of commands are supported, for example '0x00-0xff'.
+
+sgio_write_filter (RW)
+----------------------
+When read, this file will display a list of SCSI commands (i.e. values of
+the first byte of a CDB) that are available for unprivileged users
+when the block device is open for writing.  Writing to this file behaves
+as for sgio_read_filter.
 
 
 Jens Axboe <jens.axboe@oracle.com>, February 2009
diff --git a/block/Kconfig b/block/Kconfig
index 09acf1b..7c369d9 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -65,6 +65,16 @@ config BLK_DEV_BSG
 
 	  If unsure, say Y.
 
+config BLK_DEV_SG_FILTER_SYSFS
+	bool "Customizable SG_IO filters in sysfs"
+	default y
+	help
+	  Saying Y here will let you use sysfs to customize the list
+	  of SCSI commands that are available (via /dev/sg, /dev/bsg or
+	  ioctls such as SG_IO) to unprivileged users.
+
+	  If unsure, say Y.
+
 config BLK_DEV_BSGLIB
 	bool "Block layer SG support v4 helper lib"
 	default n
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 5a0de07..b287d62 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -394,6 +394,43 @@ static struct queue_sysfs_entry queue_random_entry = {
 	.store = queue_store_random,
 };
 
+#ifdef CONFIG_BLK_DEV_SG_FILTER_SYSFS
+static ssize_t queue_sgio_filter_read_show(struct request_queue *q, char *page)
+{
+	return blk_filter_show(q, page, READ);
+}
+
+static ssize_t queue_sgio_filter_write_show(struct request_queue *q,
+				 char *page)
+{
+	return blk_filter_show(q, page, WRITE);
+}
+
+static ssize_t queue_sgio_filter_read_store(struct request_queue *q,
+				    const char *page, size_t count)
+{
+	return blk_filter_store(q, page, count, READ);
+}
+
+static ssize_t queue_sgio_filter_write_store(struct request_queue *q,
+				     const char *page, size_t count)
+{
+	return blk_filter_store(q, page, count, WRITE);
+}
+
+static struct queue_sysfs_entry queue_sgio_filter_read_entry = {
+	.attr = { .name = "sgio_filter_read", .mode = S_IRUGO | S_IWUSR },
+	.show = queue_sgio_filter_read_show,
+	.store = queue_sgio_filter_read_store,
+};
+
+static struct queue_sysfs_entry queue_sgio_filter_write_entry = {
+	.attr = {.name = "sgio_filter_write", .mode = S_IRUGO | S_IWUSR },
+	.show = queue_sgio_filter_write_show,
+	.store = queue_sgio_filter_write_store,
+};
+#endif
+
 static struct attribute *default_attrs[] = {
 	&queue_requests_entry.attr,
 	&queue_ra_entry.attr,
@@ -416,6 +453,10 @@ static struct attribute *default_attrs[] = {
 	&queue_rq_affinity_entry.attr,
 	&queue_iostats_entry.attr,
 	&queue_random_entry.attr,
+#ifdef CONFIG_BLK_DEV_SG_FILTER_SYSFS
+	&queue_sgio_filter_read_entry.attr,
+	&queue_sgio_filter_write_entry.attr,
+#endif
 	NULL,
 };
 
diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index c8862e9..61a43a6 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -18,6 +18,7 @@
  */
 #include <linux/kernel.h>
 #include <linux/errno.h>
+#include <linux/ctype.h>
 #include <linux/string.h>
 #include <linux/module.h>
 #include <linux/blkdev.h>
@@ -110,6 +111,8 @@ static int sg_emulated_host(struct request_queue *q, int __user *p)
 
 static void blk_set_cmd_filter_defaults(struct blk_cmd_filter *filter)
 {
+	memset(filter, 0, sizeof(*filter));
+
 	/* Basic read-only commands */
 	__set_bit(TEST_UNIT_READY, filter->read_ok);
 	__set_bit(REQUEST_SENSE, filter->read_ok);
@@ -738,6 +741,103 @@ int scsi_cmd_blk_ioctl(struct block_device *bd, fmode_t mode,
 }
 EXPORT_SYMBOL(scsi_cmd_blk_ioctl);
 
+#ifdef CONFIG_BLK_DEV_SG_FILTER_SYSFS
+ssize_t blk_filter_show(struct request_queue *q, char *page, int rw)
+{
+	struct blk_cmd_filter *filter;
+	char *p = page;
+	unsigned long *okbits;
+	int i;
+
+	filter = q->cmd_filter;
+	if (!filter)
+		filter = &blk_default_cmd_filter;
+
+	if (rw == READ)
+		okbits = filter->read_ok;
+	else
+		okbits = filter->write_ok;
+
+	for (i = 0; i < BLK_SCSI_MAX_CMDS; i++)
+		if (test_bit(i, okbits))
+			p += sprintf(p, "0x%02x ", i);
+
+	if (p > page)
+		p[-1] = '\n';
+
+	return p - page;
+}
+EXPORT_SYMBOL_GPL(blk_filter_show);
+
+ssize_t blk_filter_store(struct request_queue *q,
+			 const char *page, size_t count, int rw)
+{
+	unsigned long okbits[BLK_SCSI_CMD_PER_LONG], *target_okbits;
+	bool set;
+	const char *p = page;
+	char *endp;
+	int start = -1, cmd;
+
+	if (!q->cmd_filter) {
+		q->cmd_filter = kmalloc(sizeof(struct blk_cmd_filter),
+					GFP_KERNEL);
+		blk_set_cmd_filter_defaults(q->cmd_filter);
+	}
+
+	if (rw == READ)
+		target_okbits = q->cmd_filter->read_ok;
+	else
+		target_okbits = q->cmd_filter->write_ok;
+
+	set = (p[0] != '-');
+	if (p[0] != '-' && p[0] != '+')
+		memset(okbits, 0, sizeof(okbits));
+	else {
+		memcpy(okbits, target_okbits, sizeof(okbits));
+		p++;
+	}
+
+	while (p < page + count) {
+		if (start == -1 && isspace(*p)) {
+			p++;
+			continue;
+		}
+
+		cmd = simple_strtol(p, &endp, 0);
+
+		/* all of these cases means invalid input, so do nothing. */
+		if (endp == p || cmd < 0 || cmd >= BLK_SCSI_MAX_CMDS ||
+		    (start != -1 && endp < page + count && !isspace(*endp)))
+			return -EINVAL;
+
+		p = endp;
+		if (p < page + count && *p == '-') {
+			BUG_ON(start != -1);
+			start = cmd;
+			p++;
+			continue;
+		}
+
+		if (start == -1)
+			start = cmd;
+
+		for (; start <= cmd; start++)
+			if (set)
+				__set_bit(start, okbits);
+			else
+				__clear_bit(start, okbits);
+		start = -1;
+	}
+
+	if (start != -1)
+		return -EINVAL;
+
+	memcpy(target_okbits, okbits, sizeof(okbits));
+	return count;
+}
+EXPORT_SYMBOL_GPL(blk_filter_store);
+#endif
+
 static int __init blk_scsi_ioctl_init(void)
 {
 	blk_set_cmd_filter_defaults(&blk_default_cmd_filter);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b5c5f8a..18e7c25 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1012,9 +1012,30 @@ static inline int sb_issue_zeroout(struct super_block *sb, sector_t block,
 				    gfp_mask);
 }
 
+/*
+ * command filter functions
+ */
 extern int blk_verify_command(struct blk_cmd_filter *filter,
 			      unsigned char *cmd, fmode_t has_write_perm);
 
+#ifdef CONFIG_BLK_DEV_SG_FILTER_SYSFS
+ssize_t blk_filter_show(struct request_queue *q, char *page, int rw);
+ssize_t blk_filter_store(struct request_queue *q,
+			 const char *page, size_t count, int rw);
+#else
+static inline ssize_t blk_filter_show(struct request_queue *q, char *page, int rw)
+{
+	return -EINVAL;
+}
+
+static inline ssize_t blk_filter_store(struct request_queue *q,
+				       const char *page, size_t count, int rw);
+{
+	return -EINVAL;
+}
+#endif /* CONFIG_BLK_DEV_SG_FILTER_SYSFS */
+
+
 enum blk_default_limits {
 	BLK_MAX_SEGMENTS	= 128,
 	BLK_SAFE_MAX_SECTORS	= 255,
-- 
1.7.1

Re: [PATCH 2/3] scsi: create an all-zero filter for scanners

[Paolo Bonzini]

Il 12/09/2012 14:36, Alan Cox ha scritto:
>> >  	switch (sdev->type) {
>> > +	case TYPE_SCANNER:
>> > +		sdev->request_queue->cmd_filter =
>> > +			kzalloc(sizeof(struct blk_cmd_filter), GFP_KERNEL);
>> > +		/* fallthrough */
> Is that really desireable in the kzalloc failing case ?

Hmm, there is another kmalloc failure in the series that is worse than
this one, actually.

Paolo

Re: [PATCH 2/3] scsi: create an all-zero filter for scanners

[Alan Cox]

On Wed, 12 Sep 2012 13:23:43 +0200
Paolo Bonzini <pbonzini@redhat.com> wrote:

> Using /dev/sg for scanners is blocked from unprivileged users.  Reimplement
> this using customizable command filters, so that the sysfs knobs will work
> in this case too.
> 
> Cc: linux-iscsi@vger.kernel.org
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  drivers/scsi/scsi_scan.c |    6 +++++-
>  drivers/scsi/sg.c        |    3 ---
>  2 files changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
> index 56a9379..d168c15 100644
> --- a/drivers/scsi/scsi_scan.c
> +++ b/drivers/scsi/scsi_scan.c
> @@ -773,13 +773,17 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
>  	}
>  
>  	switch (sdev->type) {
> +	case TYPE_SCANNER:
> +		sdev->request_queue->cmd_filter =
> +			kzalloc(sizeof(struct blk_cmd_filter), GFP_KERNEL);
> +		/* fallthrough */

Is that really desireable in the kzalloc failing case ?

[PATCH 2/3] scsi: create an all-zero filter for scanners

[Paolo Bonzini]

Using /dev/sg for scanners is blocked from unprivileged users.  Reimplement
this using customizable command filters, so that the sysfs knobs will work
in this case too.

Cc: linux-scsi@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 drivers/scsi/scsi_scan.c |    6 +++++-
 drivers/scsi/sg.c        |    3 ---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 56a9379..d168c15 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -773,13 +773,17 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
 	}
 
 	switch (sdev->type) {
+	case TYPE_SCANNER:
+		sdev->request_queue->cmd_filter =
+			kzalloc(sizeof(struct blk_cmd_filter), GFP_KERNEL);
+		/* fallthrough */
+
 	case TYPE_RBC:
 	case TYPE_TAPE:
 	case TYPE_DISK:
 	case TYPE_PRINTER:
 	case TYPE_MOD:
 	case TYPE_PROCESSOR:
-	case TYPE_SCANNER:
 	case TYPE_MEDIUM_CHANGER:
 	case TYPE_ENCLOSURE:
 	case TYPE_COMM:
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 2ba7c82..c7474f5 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -219,9 +219,6 @@ static int sg_allow_access(struct file *filp, unsigned char *cmd)
 	struct sg_fd *sfp = filp->private_data;
 	struct request_queue *q = sfp->parentdp->device->request_queue;
 
-	if (sfp->parentdp->device->type == TYPE_SCANNER)
-		return 0;
-
 	return blk_verify_command(q->cmd_filter,
 				  cmd, filp->f_mode & FMODE_WRITE);
 }
-- 
1.7.1