linux/block/cmd-filter.c
Jens Axboe 2dc75d3c3b block: disable sysfs parts of the disk command filter
We still have life time issues with the sysfs command filter kobject,
so disable it for 2.6.27 release. We can revisit this and make it work
properly for 2.6.28, for 2.6.27 release it's too risky.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-09-11 14:20:23 +02:00

238 lines
5.5 KiB
C

/*
* 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/capability.h>
#include <linux/bitops.h>
#include <scsi/scsi.h>
#include <linux/cdrom.h>
int blk_verify_command(struct blk_cmd_filter *filter,
unsigned char *cmd, int has_write_perm)
{
/* 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);
#if 0
/* and now, the sysfs stuff */
static ssize_t rcf_cmds_show(struct blk_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)) {
npage += sprintf(npage, "0x%02x", i);
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_cmd_filter *filter, char *page)
{
return rcf_cmds_show(filter, page, READ);
}
static ssize_t rcf_writecmds_show(struct blk_cmd_filter *filter,
char *page)
{
return rcf_cmds_show(filter, page, WRITE);
}
static ssize_t rcf_cmds_store(struct blk_cmd_filter *filter,
const char *page, size_t count, int rw)
{
unsigned long okbits[BLK_SCSI_CMD_PER_LONG], *target_okbits;
int cmd, set;
char *p, *status;
if (rw == READ) {
memcpy(&okbits, filter->read_ok, sizeof(okbits));
target_okbits = filter->read_ok;
} else {
memcpy(&okbits, filter->write_ok, sizeof(okbits));
target_okbits = filter->write_ok;
}
while ((p = strsep((char **)&page, " ")) != NULL) {
set = 1;
if (p[0] == '+') {
p++;
} else if (p[0] == '-') {
set = 0;
p++;
}
cmd = simple_strtol(p, &status, 16);
/* either of these cases means invalid input, so do nothing. */
if ((status == p) || cmd >= BLK_SCSI_MAX_CMDS)
return -EINVAL;
if (set)
__set_bit(cmd, okbits);
else
__clear_bit(cmd, okbits);
}
memcpy(target_okbits, okbits, sizeof(okbits));
return count;
}
static ssize_t rcf_readcmds_store(struct blk_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_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_cmd_filter *, char *);
ssize_t (*store)(struct blk_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_cmd_filter *filter;
filter = container_of(kobj, struct blk_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_cmd_filter *filter;
if (!capable(CAP_SYS_RAWIO))
return -EPERM;
if (!entry->store)
return -EINVAL;
filter = container_of(kobj, struct blk_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,
};
int blk_register_filter(struct gendisk *disk)
{
int ret;
struct blk_cmd_filter *filter = &disk->queue->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;
return 0;
}
EXPORT_SYMBOL(blk_register_filter);
void blk_unregister_filter(struct gendisk *disk)
{
struct blk_cmd_filter *filter = &disk->queue->cmd_filter;
kobject_put(&filter->kobj);
kobject_put(disk->holder_dir->parent);
}
EXPORT_SYMBOL(blk_unregister_filter);
#endif