allow userspace to modify scsi command filter on per device basis

This patch exports the per-gendisk command filter to user space through
sysfs, so it can be changed by the system administrator.
All users of the old cmd filter have been converted to use the new one.

Original patch from Peter Jones.

Signed-off-by: Adel Gadllah <adel.gadllah@gmail.com>
Signed-off-by: Peter Jones <pjones@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 325 insertions, 0 deletions

diff --git a/block/cmd-filter.c b/block/cmd-filter.c
new file mode 100644
index 00000000000..35e327ceaa9
--- /dev/null
+++ b/block/cmd-filter.c
@@ -0,0 +1,325 @@
+/*
+ * Copyright 2004 Peter M. Jones <pjones@redhat.com>
+ *
+ * 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/list.h>
+#include <linux/genhd.h>
+#include <linux/spinlock.h>
+#include <linux/parser.h>
+#include <linux/capability.h>
+#include <linux/bitops.h>
+
+#include <scsi/scsi.h>
+#include <linux/cdrom.h>
+
+int blk_cmd_filter_verify_command(struct blk_scsi_cmd_filter *filter,
+				  unsigned char *cmd, mode_t *f_mode)
+{
+	/* 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) && (*f_mode & FMODE_WRITE))
+		return 0;
+
+	return -EPERM;
+}
+EXPORT_SYMBOL(blk_cmd_filter_verify_command);
+
+int blk_verify_command(struct file *file, unsigned char *cmd)
+{
+	struct gendisk *disk;
+	struct inode *inode;
+
+	if (!file)
+		return -EINVAL;
+
+	inode = file->f_dentry->d_inode;
+	if (!inode)
+		return -EINVAL;
+
+	disk = inode->i_bdev->bd_disk;
+
+	return blk_cmd_filter_verify_command(&disk->cmd_filter,
+						 cmd, &file->f_mode);
+}
+EXPORT_SYMBOL(blk_verify_command);
+
+/* and now, the sysfs stuff */
+static ssize_t rcf_cmds_show(struct blk_scsi_cmd_filter *filter, char *page,
+			     int rw)
+{
+	char *npage = page;
+	unsigned long *okbits;
+	int i;
+
+	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)) {
+			sprintf(npage, "%02x", i);
+			npage += 2;
+			if (i < BLK_SCSI_MAX_CMDS - 1)
+				sprintf(npage++, " ");
+		}
+	}
+
+	if (npage != page)
+		npage += sprintf(npage, "\n");
+
+	return npage - page;
+}
+
+static ssize_t rcf_readcmds_show(struct blk_scsi_cmd_filter *filter, char *page)
+{
+	return rcf_cmds_show(filter, page, READ);
+}
+
+static ssize_t rcf_writecmds_show(struct blk_scsi_cmd_filter *filter,
+				 char *page)
+{
+	return rcf_cmds_show(filter, page, WRITE);
+}
+
+static ssize_t rcf_cmds_store(struct blk_scsi_cmd_filter *filter,
+			      const char *page, size_t count, int rw)
+{
+	ssize_t ret = 0;
+	unsigned long okbits[BLK_SCSI_CMD_PER_LONG], *target_okbits;
+	int cmd, status, len;
+	substring_t ss;
+
+	memset(&okbits, 0, sizeof(okbits));
+
+	for (len = strlen(page); len > 0; len -= 3) {
+		if (len < 2)
+			break;
+		ss.from = (char *) page + ret;
+		ss.to = (char *) page + ret + 2;
+		ret += 3;
+		status = match_hex(&ss, &cmd);
+		/* either of these cases means invalid input, so do nothing. */
+		if (status || cmd >= BLK_SCSI_MAX_CMDS)
+			return -EINVAL;
+
+		__set_bit(cmd, okbits);
+	}
+
+	if (rw == READ)
+		target_okbits = filter->read_ok;
+	else
+		target_okbits = filter->write_ok;
+
+	memmove(target_okbits, okbits, sizeof(okbits));
+	return count;
+}
+
+static ssize_t rcf_readcmds_store(struct blk_scsi_cmd_filter *filter,
+				  const char *page, size_t count)
+{
+	return rcf_cmds_store(filter, page, count, READ);
+}
+
+static ssize_t rcf_writecmds_store(struct blk_scsi_cmd_filter *filter,
+				   const char *page, size_t count)
+{
+	return rcf_cmds_store(filter, page, count, WRITE);
+}
+
+struct rcf_sysfs_entry {
+	struct attribute attr;
+	ssize_t (*show)(struct blk_scsi_cmd_filter *, char *);
+	ssize_t (*store)(struct blk_scsi_cmd_filter *, const char *, size_t);
+};
+
+static struct rcf_sysfs_entry rcf_readcmds_entry = {
+	.attr = { .name = "read_table", .mode = S_IRUGO | S_IWUSR },
+	.show = rcf_readcmds_show,
+	.store = rcf_readcmds_store,
+};
+
+static struct rcf_sysfs_entry rcf_writecmds_entry = {
+	.attr = {.name = "write_table", .mode = S_IRUGO | S_IWUSR },
+	.show = rcf_writecmds_show,
+	.store = rcf_writecmds_store,
+};
+
+static struct attribute *default_attrs[] = {
+	&rcf_readcmds_entry.attr,
+	&rcf_writecmds_entry.attr,
+	NULL,
+};
+
+#define to_rcf(atr) container_of((atr), struct rcf_sysfs_entry, attr)
+
+static ssize_t
+rcf_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
+{
+	struct rcf_sysfs_entry *entry = to_rcf(attr);
+	struct blk_scsi_cmd_filter *filter;
+
+	filter = container_of(kobj, struct blk_scsi_cmd_filter, kobj);
+	if (entry->show)
+		return entry->show(filter, page);
+
+	return 0;
+}
+
+static ssize_t
+rcf_attr_store(struct kobject *kobj, struct attribute *attr,
+			const char *page, size_t length)
+{
+	struct rcf_sysfs_entry *entry = to_rcf(attr);
+	struct blk_scsi_cmd_filter *filter;
+
+	if (!capable(CAP_SYS_RAWIO))
+		return -EPERM;
+
+	if (!entry->store)
+		return -EINVAL;
+
+	filter = container_of(kobj, struct blk_scsi_cmd_filter, kobj);
+	return entry->store(filter, page, length);
+}
+
+static struct sysfs_ops rcf_sysfs_ops = {
+	.show = rcf_attr_show,
+	.store = rcf_attr_store,
+};
+
+static struct kobj_type rcf_ktype = {
+	.sysfs_ops = &rcf_sysfs_ops,
+	.default_attrs = default_attrs,
+};
+
+static void rcf_set_defaults(struct blk_scsi_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_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(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);
+}
+
+int blk_register_filter(struct gendisk *disk)
+{
+	int ret;
+	struct blk_scsi_cmd_filter *filter = &disk->cmd_filter;
+	struct kobject *parent = kobject_get(disk->holder_dir->parent);
+
+	if (!parent)
+		return -ENODEV;
+
+	ret = kobject_init_and_add(&filter->kobj, &rcf_ktype, parent,
+				 "%s", "cmd_filter");
+
+	if (ret < 0)
+		return ret;
+
+	rcf_set_defaults(filter);
+	return 0;
+}
+
+void blk_unregister_filter(struct gendisk *disk)
+{
+	struct blk_scsi_cmd_filter *filter = &disk->cmd_filter;
+
+	kobject_put(&filter->kobj);
+	kobject_put(disk->holder_dir->parent);
+}
+