linux/drivers/md/dm-unstripe.c
Tushar Sugandhi 8ec456629d dm: update target status functions to support IMA measurement
For device mapper targets to take advantage of IMA's measurement
capabilities, the status functions for the individual targets need to be
updated to handle the status_type_t case for value STATUSTYPE_IMA.

Update status functions for the following target types, to log their
respective attributes to be measured using IMA.
 01. cache
 02. crypt
 03. integrity
 04. linear
 05. mirror
 06. multipath
 07. raid
 08. snapshot
 09. striped
 10. verity

For rest of the targets, handle the STATUSTYPE_IMA case by setting the
measurement buffer to NULL.

For IMA to measure the data on a given system, the IMA policy on the
system needs to be updated to have the following line, and the system
needs to be restarted for the measurements to take effect.

/etc/ima/ima-policy
 measure func=CRITICAL_DATA label=device-mapper template=ima-buf

The measurements will be reflected in the IMA logs, which are located at:

/sys/kernel/security/integrity/ima/ascii_runtime_measurements
/sys/kernel/security/integrity/ima/binary_runtime_measurements

These IMA logs can later be consumed by various attestation clients
running on the system, and send them to external services for attesting
the system.

The DM target data measured by IMA subsystem can alternatively
be queried from userspace by setting DM_IMA_MEASUREMENT_FLAG with
DM_TABLE_STATUS_CMD.

Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2021-08-10 13:34:23 -04:00

212 lines
4.7 KiB
C

/*
* Copyright (C) 2017 Intel Corporation.
*
* This file is released under the GPL.
*/
#include "dm.h"
#include <linux/module.h>
struct unstripe_c {
struct dm_dev *dev;
sector_t physical_start;
uint32_t stripes;
uint32_t unstripe;
sector_t unstripe_width;
sector_t unstripe_offset;
uint32_t chunk_size;
u8 chunk_shift;
};
#define DM_MSG_PREFIX "unstriped"
static void cleanup_unstripe(struct unstripe_c *uc, struct dm_target *ti)
{
if (uc->dev)
dm_put_device(ti, uc->dev);
kfree(uc);
}
/*
* Contruct an unstriped mapping.
* <number of stripes> <chunk size> <stripe #> <dev_path> <offset>
*/
static int unstripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
struct unstripe_c *uc;
sector_t tmp_len;
unsigned long long start;
char dummy;
if (argc != 5) {
ti->error = "Invalid number of arguments";
return -EINVAL;
}
uc = kzalloc(sizeof(*uc), GFP_KERNEL);
if (!uc) {
ti->error = "Memory allocation for unstriped context failed";
return -ENOMEM;
}
if (kstrtouint(argv[0], 10, &uc->stripes) || !uc->stripes) {
ti->error = "Invalid stripe count";
goto err;
}
if (kstrtouint(argv[1], 10, &uc->chunk_size) || !uc->chunk_size) {
ti->error = "Invalid chunk_size";
goto err;
}
if (kstrtouint(argv[2], 10, &uc->unstripe)) {
ti->error = "Invalid stripe number";
goto err;
}
if (uc->unstripe > uc->stripes && uc->stripes > 1) {
ti->error = "Please provide stripe between [0, # of stripes]";
goto err;
}
if (dm_get_device(ti, argv[3], dm_table_get_mode(ti->table), &uc->dev)) {
ti->error = "Couldn't get striped device";
goto err;
}
if (sscanf(argv[4], "%llu%c", &start, &dummy) != 1 || start != (sector_t)start) {
ti->error = "Invalid striped device offset";
goto err;
}
uc->physical_start = start;
uc->unstripe_offset = uc->unstripe * uc->chunk_size;
uc->unstripe_width = (uc->stripes - 1) * uc->chunk_size;
uc->chunk_shift = is_power_of_2(uc->chunk_size) ? fls(uc->chunk_size) - 1 : 0;
tmp_len = ti->len;
if (sector_div(tmp_len, uc->chunk_size)) {
ti->error = "Target length not divisible by chunk size";
goto err;
}
if (dm_set_target_max_io_len(ti, uc->chunk_size)) {
ti->error = "Failed to set max io len";
goto err;
}
ti->private = uc;
return 0;
err:
cleanup_unstripe(uc, ti);
return -EINVAL;
}
static void unstripe_dtr(struct dm_target *ti)
{
struct unstripe_c *uc = ti->private;
cleanup_unstripe(uc, ti);
}
static sector_t map_to_core(struct dm_target *ti, struct bio *bio)
{
struct unstripe_c *uc = ti->private;
sector_t sector = bio->bi_iter.bi_sector;
sector_t tmp_sector = sector;
/* Shift us up to the right "row" on the stripe */
if (uc->chunk_shift)
tmp_sector >>= uc->chunk_shift;
else
sector_div(tmp_sector, uc->chunk_size);
sector += uc->unstripe_width * tmp_sector;
/* Account for what stripe we're operating on */
return sector + uc->unstripe_offset;
}
static int unstripe_map(struct dm_target *ti, struct bio *bio)
{
struct unstripe_c *uc = ti->private;
bio_set_dev(bio, uc->dev->bdev);
bio->bi_iter.bi_sector = map_to_core(ti, bio) + uc->physical_start;
return DM_MAPIO_REMAPPED;
}
static void unstripe_status(struct dm_target *ti, status_type_t type,
unsigned int status_flags, char *result, unsigned int maxlen)
{
struct unstripe_c *uc = ti->private;
unsigned int sz = 0;
switch (type) {
case STATUSTYPE_INFO:
break;
case STATUSTYPE_TABLE:
DMEMIT("%d %llu %d %s %llu",
uc->stripes, (unsigned long long)uc->chunk_size, uc->unstripe,
uc->dev->name, (unsigned long long)uc->physical_start);
break;
case STATUSTYPE_IMA:
*result = '\0';
break;
}
}
static int unstripe_iterate_devices(struct dm_target *ti,
iterate_devices_callout_fn fn, void *data)
{
struct unstripe_c *uc = ti->private;
return fn(ti, uc->dev, uc->physical_start, ti->len, data);
}
static void unstripe_io_hints(struct dm_target *ti,
struct queue_limits *limits)
{
struct unstripe_c *uc = ti->private;
limits->chunk_sectors = uc->chunk_size;
}
static struct target_type unstripe_target = {
.name = "unstriped",
.version = {1, 1, 0},
.features = DM_TARGET_NOWAIT,
.module = THIS_MODULE,
.ctr = unstripe_ctr,
.dtr = unstripe_dtr,
.map = unstripe_map,
.status = unstripe_status,
.iterate_devices = unstripe_iterate_devices,
.io_hints = unstripe_io_hints,
};
static int __init dm_unstripe_init(void)
{
return dm_register_target(&unstripe_target);
}
static void __exit dm_unstripe_exit(void)
{
dm_unregister_target(&unstripe_target);
}
module_init(dm_unstripe_init);
module_exit(dm_unstripe_exit);
MODULE_DESCRIPTION(DM_NAME " unstriped target");
MODULE_ALIAS("dm-unstriped");
MODULE_AUTHOR("Scott Bauer <scott.bauer@intel.com>");
MODULE_LICENSE("GPL");