linux/drivers/md/dm-ima.c
Mike Snitzer 564b5c5476 dm table: audit all dm_table_get_target() callers
All callers of dm_table_get_target() are expected to do proper bounds
checking on the index they pass.

Move dm_table_get_target() to dm-core.h to make it extra clear that only
DM core code should be using it. Switch it to be inlined while at it.

Standardize all DM core callers to use the same for loop pattern and
make associated variables as local as possible. Rename some variables
(e.g. s/table/t/ and s/tgt/ti/) along the way.

Signed-off-by: Mike Snitzer <snitzer@kernel.org>
2022-07-07 11:49:34 -04:00

750 lines
21 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2021 Microsoft Corporation
*
* Author: Tushar Sugandhi <tusharsu@linux.microsoft.com>
*
* File: dm-ima.c
* Enables IMA measurements for DM targets
*/
#include "dm-core.h"
#include "dm-ima.h"
#include <linux/ima.h>
#include <linux/sched/mm.h>
#include <crypto/hash.h>
#include <linux/crypto.h>
#include <crypto/hash_info.h>
#define DM_MSG_PREFIX "ima"
/*
* Internal function to prefix separator characters in input buffer with escape
* character, so that they don't interfere with the construction of key-value pairs,
* and clients can split the key1=val1,key2=val2,key3=val3; pairs properly.
*/
static void fix_separator_chars(char **buf)
{
int l = strlen(*buf);
int i, j, sp = 0;
for (i = 0; i < l; i++)
if ((*buf)[i] == '\\' || (*buf)[i] == ';' || (*buf)[i] == '=' || (*buf)[i] == ',')
sp++;
if (!sp)
return;
for (i = l-1, j = i+sp; i >= 0; i--) {
(*buf)[j--] = (*buf)[i];
if ((*buf)[i] == '\\' || (*buf)[i] == ';' || (*buf)[i] == '=' || (*buf)[i] == ',')
(*buf)[j--] = '\\';
}
}
/*
* Internal function to allocate memory for IMA measurements.
*/
static void *dm_ima_alloc(size_t len, gfp_t flags, bool noio)
{
unsigned int noio_flag;
void *ptr;
if (noio)
noio_flag = memalloc_noio_save();
ptr = kzalloc(len, flags);
if (noio)
memalloc_noio_restore(noio_flag);
return ptr;
}
/*
* Internal function to allocate and copy name and uuid for IMA measurements.
*/
static int dm_ima_alloc_and_copy_name_uuid(struct mapped_device *md, char **dev_name,
char **dev_uuid, bool noio)
{
int r;
*dev_name = dm_ima_alloc(DM_NAME_LEN*2, GFP_KERNEL, noio);
if (!(*dev_name)) {
r = -ENOMEM;
goto error;
}
*dev_uuid = dm_ima_alloc(DM_UUID_LEN*2, GFP_KERNEL, noio);
if (!(*dev_uuid)) {
r = -ENOMEM;
goto error;
}
r = dm_copy_name_and_uuid(md, *dev_name, *dev_uuid);
if (r)
goto error;
fix_separator_chars(dev_name);
fix_separator_chars(dev_uuid);
return 0;
error:
kfree(*dev_name);
kfree(*dev_uuid);
*dev_name = NULL;
*dev_uuid = NULL;
return r;
}
/*
* Internal function to allocate and copy device data for IMA measurements.
*/
static int dm_ima_alloc_and_copy_device_data(struct mapped_device *md, char **device_data,
unsigned int num_targets, bool noio)
{
char *dev_name = NULL, *dev_uuid = NULL;
int r;
r = dm_ima_alloc_and_copy_name_uuid(md, &dev_name, &dev_uuid, noio);
if (r)
return r;
*device_data = dm_ima_alloc(DM_IMA_DEVICE_BUF_LEN, GFP_KERNEL, noio);
if (!(*device_data)) {
r = -ENOMEM;
goto error;
}
scnprintf(*device_data, DM_IMA_DEVICE_BUF_LEN,
"name=%s,uuid=%s,major=%d,minor=%d,minor_count=%d,num_targets=%u;",
dev_name, dev_uuid, md->disk->major, md->disk->first_minor,
md->disk->minors, num_targets);
error:
kfree(dev_name);
kfree(dev_uuid);
return r;
}
/*
* Internal wrapper function to call IMA to measure DM data.
*/
static void dm_ima_measure_data(const char *event_name, const void *buf, size_t buf_len,
bool noio)
{
unsigned int noio_flag;
if (noio)
noio_flag = memalloc_noio_save();
ima_measure_critical_data(DM_NAME, event_name, buf, buf_len,
false, NULL, 0);
if (noio)
memalloc_noio_restore(noio_flag);
}
/*
* Internal function to allocate and copy current device capacity for IMA measurements.
*/
static int dm_ima_alloc_and_copy_capacity_str(struct mapped_device *md, char **capacity_str,
bool noio)
{
sector_t capacity;
capacity = get_capacity(md->disk);
*capacity_str = dm_ima_alloc(DM_IMA_DEVICE_CAPACITY_BUF_LEN, GFP_KERNEL, noio);
if (!(*capacity_str))
return -ENOMEM;
scnprintf(*capacity_str, DM_IMA_DEVICE_BUF_LEN, "current_device_capacity=%llu;",
capacity);
return 0;
}
/*
* Initialize/reset the dm ima related data structure variables.
*/
void dm_ima_reset_data(struct mapped_device *md)
{
memset(&(md->ima), 0, sizeof(md->ima));
md->ima.dm_version_str_len = strlen(DM_IMA_VERSION_STR);
}
/*
* Build up the IMA data for each target, and finally measure.
*/
void dm_ima_measure_on_table_load(struct dm_table *table, unsigned int status_flags)
{
size_t device_data_buf_len, target_metadata_buf_len, target_data_buf_len, l = 0;
char *target_metadata_buf = NULL, *target_data_buf = NULL, *digest_buf = NULL;
char *ima_buf = NULL, *device_data_buf = NULL;
int digest_size, last_target_measured = -1, r;
status_type_t type = STATUSTYPE_IMA;
size_t cur_total_buf_len = 0;
unsigned int num_targets, i;
SHASH_DESC_ON_STACK(shash, NULL);
struct crypto_shash *tfm = NULL;
u8 *digest = NULL;
bool noio = false;
/*
* In below hash_alg_prefix_len assignment +1 is for the additional char (':'),
* when prefixing the hash value with the hash algorithm name. e.g. sha256:<hash_value>.
*/
const size_t hash_alg_prefix_len = strlen(DM_IMA_TABLE_HASH_ALG) + 1;
char table_load_event_name[] = "dm_table_load";
ima_buf = dm_ima_alloc(DM_IMA_MEASUREMENT_BUF_LEN, GFP_KERNEL, noio);
if (!ima_buf)
return;
target_metadata_buf = dm_ima_alloc(DM_IMA_TARGET_METADATA_BUF_LEN, GFP_KERNEL, noio);
if (!target_metadata_buf)
goto error;
target_data_buf = dm_ima_alloc(DM_IMA_TARGET_DATA_BUF_LEN, GFP_KERNEL, noio);
if (!target_data_buf)
goto error;
num_targets = table->num_targets;
if (dm_ima_alloc_and_copy_device_data(table->md, &device_data_buf, num_targets, noio))
goto error;
tfm = crypto_alloc_shash(DM_IMA_TABLE_HASH_ALG, 0, 0);
if (IS_ERR(tfm))
goto error;
shash->tfm = tfm;
digest_size = crypto_shash_digestsize(tfm);
digest = dm_ima_alloc(digest_size, GFP_KERNEL, noio);
if (!digest)
goto error;
r = crypto_shash_init(shash);
if (r)
goto error;
memcpy(ima_buf + l, DM_IMA_VERSION_STR, table->md->ima.dm_version_str_len);
l += table->md->ima.dm_version_str_len;
device_data_buf_len = strlen(device_data_buf);
memcpy(ima_buf + l, device_data_buf, device_data_buf_len);
l += device_data_buf_len;
for (i = 0; i < num_targets; i++) {
struct dm_target *ti = dm_table_get_target(table, i);
last_target_measured = 0;
/*
* First retrieve the target metadata.
*/
scnprintf(target_metadata_buf, DM_IMA_TARGET_METADATA_BUF_LEN,
"target_index=%d,target_begin=%llu,target_len=%llu,",
i, ti->begin, ti->len);
target_metadata_buf_len = strlen(target_metadata_buf);
/*
* Then retrieve the actual target data.
*/
if (ti->type->status)
ti->type->status(ti, type, status_flags, target_data_buf,
DM_IMA_TARGET_DATA_BUF_LEN);
else
target_data_buf[0] = '\0';
target_data_buf_len = strlen(target_data_buf);
/*
* Check if the total data can fit into the IMA buffer.
*/
cur_total_buf_len = l + target_metadata_buf_len + target_data_buf_len;
/*
* IMA measurements for DM targets are best-effort.
* If the total data buffered so far, including the current target,
* is too large to fit into DM_IMA_MEASUREMENT_BUF_LEN, measure what
* we have in the current buffer, and continue measuring the remaining
* targets by prefixing the device metadata again.
*/
if (unlikely(cur_total_buf_len >= DM_IMA_MEASUREMENT_BUF_LEN)) {
dm_ima_measure_data(table_load_event_name, ima_buf, l, noio);
r = crypto_shash_update(shash, (const u8 *)ima_buf, l);
if (r < 0)
goto error;
memset(ima_buf, 0, DM_IMA_MEASUREMENT_BUF_LEN);
l = 0;
/*
* Each new "dm_table_load" entry in IMA log should have device data
* prefix, so that multiple records from the same "dm_table_load" for
* a given device can be linked together.
*/
memcpy(ima_buf + l, DM_IMA_VERSION_STR, table->md->ima.dm_version_str_len);
l += table->md->ima.dm_version_str_len;
memcpy(ima_buf + l, device_data_buf, device_data_buf_len);
l += device_data_buf_len;
/*
* If this iteration of the for loop turns out to be the last target
* in the table, dm_ima_measure_data("dm_table_load", ...) doesn't need
* to be called again, just the hash needs to be finalized.
* "last_target_measured" tracks this state.
*/
last_target_measured = 1;
}
/*
* Fill-in all the target metadata, so that multiple targets for the same
* device can be linked together.
*/
memcpy(ima_buf + l, target_metadata_buf, target_metadata_buf_len);
l += target_metadata_buf_len;
memcpy(ima_buf + l, target_data_buf, target_data_buf_len);
l += target_data_buf_len;
}
if (!last_target_measured) {
dm_ima_measure_data(table_load_event_name, ima_buf, l, noio);
r = crypto_shash_update(shash, (const u8 *)ima_buf, l);
if (r < 0)
goto error;
}
/*
* Finalize the table hash, and store it in table->md->ima.inactive_table.hash,
* so that the table data can be verified against the future device state change
* events, e.g. resume, rename, remove, table-clear etc.
*/
r = crypto_shash_final(shash, digest);
if (r < 0)
goto error;
digest_buf = dm_ima_alloc((digest_size*2) + hash_alg_prefix_len + 1, GFP_KERNEL, noio);
if (!digest_buf)
goto error;
snprintf(digest_buf, hash_alg_prefix_len + 1, "%s:", DM_IMA_TABLE_HASH_ALG);
for (i = 0; i < digest_size; i++)
snprintf((digest_buf + hash_alg_prefix_len + (i*2)), 3, "%02x", digest[i]);
if (table->md->ima.active_table.hash != table->md->ima.inactive_table.hash)
kfree(table->md->ima.inactive_table.hash);
table->md->ima.inactive_table.hash = digest_buf;
table->md->ima.inactive_table.hash_len = strlen(digest_buf);
table->md->ima.inactive_table.num_targets = num_targets;
if (table->md->ima.active_table.device_metadata !=
table->md->ima.inactive_table.device_metadata)
kfree(table->md->ima.inactive_table.device_metadata);
table->md->ima.inactive_table.device_metadata = device_data_buf;
table->md->ima.inactive_table.device_metadata_len = device_data_buf_len;
goto exit;
error:
kfree(digest_buf);
kfree(device_data_buf);
exit:
kfree(digest);
if (tfm)
crypto_free_shash(tfm);
kfree(ima_buf);
kfree(target_metadata_buf);
kfree(target_data_buf);
}
/*
* Measure IMA data on device resume.
*/
void dm_ima_measure_on_device_resume(struct mapped_device *md, bool swap)
{
char *device_table_data, *dev_name = NULL, *dev_uuid = NULL, *capacity_str = NULL;
char active[] = "active_table_hash=";
unsigned int active_len = strlen(active), capacity_len = 0;
unsigned int l = 0;
bool noio = true;
bool nodata = true;
int r;
device_table_data = dm_ima_alloc(DM_IMA_DEVICE_BUF_LEN, GFP_KERNEL, noio);
if (!device_table_data)
return;
r = dm_ima_alloc_and_copy_capacity_str(md, &capacity_str, noio);
if (r)
goto error;
memcpy(device_table_data + l, DM_IMA_VERSION_STR, md->ima.dm_version_str_len);
l += md->ima.dm_version_str_len;
if (swap) {
if (md->ima.active_table.hash != md->ima.inactive_table.hash)
kfree(md->ima.active_table.hash);
md->ima.active_table.hash = NULL;
md->ima.active_table.hash_len = 0;
if (md->ima.active_table.device_metadata !=
md->ima.inactive_table.device_metadata)
kfree(md->ima.active_table.device_metadata);
md->ima.active_table.device_metadata = NULL;
md->ima.active_table.device_metadata_len = 0;
md->ima.active_table.num_targets = 0;
if (md->ima.inactive_table.hash) {
md->ima.active_table.hash = md->ima.inactive_table.hash;
md->ima.active_table.hash_len = md->ima.inactive_table.hash_len;
md->ima.inactive_table.hash = NULL;
md->ima.inactive_table.hash_len = 0;
}
if (md->ima.inactive_table.device_metadata) {
md->ima.active_table.device_metadata =
md->ima.inactive_table.device_metadata;
md->ima.active_table.device_metadata_len =
md->ima.inactive_table.device_metadata_len;
md->ima.active_table.num_targets = md->ima.inactive_table.num_targets;
md->ima.inactive_table.device_metadata = NULL;
md->ima.inactive_table.device_metadata_len = 0;
md->ima.inactive_table.num_targets = 0;
}
}
if (md->ima.active_table.device_metadata) {
memcpy(device_table_data + l, md->ima.active_table.device_metadata,
md->ima.active_table.device_metadata_len);
l += md->ima.active_table.device_metadata_len;
nodata = false;
}
if (md->ima.active_table.hash) {
memcpy(device_table_data + l, active, active_len);
l += active_len;
memcpy(device_table_data + l, md->ima.active_table.hash,
md->ima.active_table.hash_len);
l += md->ima.active_table.hash_len;
memcpy(device_table_data + l, ";", 1);
l++;
nodata = false;
}
if (nodata) {
r = dm_ima_alloc_and_copy_name_uuid(md, &dev_name, &dev_uuid, noio);
if (r)
goto error;
scnprintf(device_table_data, DM_IMA_DEVICE_BUF_LEN,
"%sname=%s,uuid=%s;device_resume=no_data;",
DM_IMA_VERSION_STR, dev_name, dev_uuid);
l = strlen(device_table_data);
}
capacity_len = strlen(capacity_str);
memcpy(device_table_data + l, capacity_str, capacity_len);
l += capacity_len;
dm_ima_measure_data("dm_device_resume", device_table_data, l, noio);
kfree(dev_name);
kfree(dev_uuid);
error:
kfree(capacity_str);
kfree(device_table_data);
}
/*
* Measure IMA data on remove.
*/
void dm_ima_measure_on_device_remove(struct mapped_device *md, bool remove_all)
{
char *device_table_data, *dev_name = NULL, *dev_uuid = NULL, *capacity_str = NULL;
char active_table_str[] = "active_table_hash=";
char inactive_table_str[] = "inactive_table_hash=";
char device_active_str[] = "device_active_metadata=";
char device_inactive_str[] = "device_inactive_metadata=";
char remove_all_str[] = "remove_all=";
unsigned int active_table_len = strlen(active_table_str);
unsigned int inactive_table_len = strlen(inactive_table_str);
unsigned int device_active_len = strlen(device_active_str);
unsigned int device_inactive_len = strlen(device_inactive_str);
unsigned int remove_all_len = strlen(remove_all_str);
unsigned int capacity_len = 0;
unsigned int l = 0;
bool noio = true;
bool nodata = true;
int r;
device_table_data = dm_ima_alloc(DM_IMA_DEVICE_BUF_LEN*2, GFP_KERNEL, noio);
if (!device_table_data)
goto exit;
r = dm_ima_alloc_and_copy_capacity_str(md, &capacity_str, noio);
if (r) {
kfree(device_table_data);
goto exit;
}
memcpy(device_table_data + l, DM_IMA_VERSION_STR, md->ima.dm_version_str_len);
l += md->ima.dm_version_str_len;
if (md->ima.active_table.device_metadata) {
memcpy(device_table_data + l, device_active_str, device_active_len);
l += device_active_len;
memcpy(device_table_data + l, md->ima.active_table.device_metadata,
md->ima.active_table.device_metadata_len);
l += md->ima.active_table.device_metadata_len;
nodata = false;
}
if (md->ima.inactive_table.device_metadata) {
memcpy(device_table_data + l, device_inactive_str, device_inactive_len);
l += device_inactive_len;
memcpy(device_table_data + l, md->ima.inactive_table.device_metadata,
md->ima.inactive_table.device_metadata_len);
l += md->ima.inactive_table.device_metadata_len;
nodata = false;
}
if (md->ima.active_table.hash) {
memcpy(device_table_data + l, active_table_str, active_table_len);
l += active_table_len;
memcpy(device_table_data + l, md->ima.active_table.hash,
md->ima.active_table.hash_len);
l += md->ima.active_table.hash_len;
memcpy(device_table_data + l, ",", 1);
l++;
nodata = false;
}
if (md->ima.inactive_table.hash) {
memcpy(device_table_data + l, inactive_table_str, inactive_table_len);
l += inactive_table_len;
memcpy(device_table_data + l, md->ima.inactive_table.hash,
md->ima.inactive_table.hash_len);
l += md->ima.inactive_table.hash_len;
memcpy(device_table_data + l, ",", 1);
l++;
nodata = false;
}
/*
* In case both active and inactive tables, and corresponding
* device metadata is cleared/missing - record the name and uuid
* in IMA measurements.
*/
if (nodata) {
if (dm_ima_alloc_and_copy_name_uuid(md, &dev_name, &dev_uuid, noio))
goto error;
scnprintf(device_table_data, DM_IMA_DEVICE_BUF_LEN,
"%sname=%s,uuid=%s;device_remove=no_data;",
DM_IMA_VERSION_STR, dev_name, dev_uuid);
l = strlen(device_table_data);
}
memcpy(device_table_data + l, remove_all_str, remove_all_len);
l += remove_all_len;
memcpy(device_table_data + l, remove_all ? "y;" : "n;", 2);
l += 2;
capacity_len = strlen(capacity_str);
memcpy(device_table_data + l, capacity_str, capacity_len);
l += capacity_len;
dm_ima_measure_data("dm_device_remove", device_table_data, l, noio);
error:
kfree(device_table_data);
kfree(capacity_str);
exit:
kfree(md->ima.active_table.device_metadata);
if (md->ima.active_table.device_metadata !=
md->ima.inactive_table.device_metadata)
kfree(md->ima.inactive_table.device_metadata);
kfree(md->ima.active_table.hash);
if (md->ima.active_table.hash != md->ima.inactive_table.hash)
kfree(md->ima.inactive_table.hash);
dm_ima_reset_data(md);
kfree(dev_name);
kfree(dev_uuid);
}
/*
* Measure ima data on table clear.
*/
void dm_ima_measure_on_table_clear(struct mapped_device *md, bool new_map)
{
unsigned int l = 0, capacity_len = 0;
char *device_table_data = NULL, *dev_name = NULL, *dev_uuid = NULL, *capacity_str = NULL;
char inactive_str[] = "inactive_table_hash=";
unsigned int inactive_len = strlen(inactive_str);
bool noio = true;
bool nodata = true;
int r;
device_table_data = dm_ima_alloc(DM_IMA_DEVICE_BUF_LEN, GFP_KERNEL, noio);
if (!device_table_data)
return;
r = dm_ima_alloc_and_copy_capacity_str(md, &capacity_str, noio);
if (r)
goto error1;
memcpy(device_table_data + l, DM_IMA_VERSION_STR, md->ima.dm_version_str_len);
l += md->ima.dm_version_str_len;
if (md->ima.inactive_table.device_metadata_len &&
md->ima.inactive_table.hash_len) {
memcpy(device_table_data + l, md->ima.inactive_table.device_metadata,
md->ima.inactive_table.device_metadata_len);
l += md->ima.inactive_table.device_metadata_len;
memcpy(device_table_data + l, inactive_str, inactive_len);
l += inactive_len;
memcpy(device_table_data + l, md->ima.inactive_table.hash,
md->ima.inactive_table.hash_len);
l += md->ima.inactive_table.hash_len;
memcpy(device_table_data + l, ";", 1);
l++;
nodata = false;
}
if (nodata) {
if (dm_ima_alloc_and_copy_name_uuid(md, &dev_name, &dev_uuid, noio))
goto error2;
scnprintf(device_table_data, DM_IMA_DEVICE_BUF_LEN,
"%sname=%s,uuid=%s;table_clear=no_data;",
DM_IMA_VERSION_STR, dev_name, dev_uuid);
l = strlen(device_table_data);
}
capacity_len = strlen(capacity_str);
memcpy(device_table_data + l, capacity_str, capacity_len);
l += capacity_len;
dm_ima_measure_data("dm_table_clear", device_table_data, l, noio);
if (new_map) {
if (md->ima.inactive_table.hash &&
md->ima.inactive_table.hash != md->ima.active_table.hash)
kfree(md->ima.inactive_table.hash);
md->ima.inactive_table.hash = NULL;
md->ima.inactive_table.hash_len = 0;
if (md->ima.inactive_table.device_metadata &&
md->ima.inactive_table.device_metadata != md->ima.active_table.device_metadata)
kfree(md->ima.inactive_table.device_metadata);
md->ima.inactive_table.device_metadata = NULL;
md->ima.inactive_table.device_metadata_len = 0;
md->ima.inactive_table.num_targets = 0;
if (md->ima.active_table.hash) {
md->ima.inactive_table.hash = md->ima.active_table.hash;
md->ima.inactive_table.hash_len = md->ima.active_table.hash_len;
}
if (md->ima.active_table.device_metadata) {
md->ima.inactive_table.device_metadata =
md->ima.active_table.device_metadata;
md->ima.inactive_table.device_metadata_len =
md->ima.active_table.device_metadata_len;
md->ima.inactive_table.num_targets =
md->ima.active_table.num_targets;
}
}
kfree(dev_name);
kfree(dev_uuid);
error2:
kfree(capacity_str);
error1:
kfree(device_table_data);
}
/*
* Measure IMA data on device rename.
*/
void dm_ima_measure_on_device_rename(struct mapped_device *md)
{
char *old_device_data = NULL, *new_device_data = NULL, *combined_device_data = NULL;
char *new_dev_name = NULL, *new_dev_uuid = NULL, *capacity_str = NULL;
bool noio = true;
int r;
if (dm_ima_alloc_and_copy_device_data(md, &new_device_data,
md->ima.active_table.num_targets, noio))
return;
if (dm_ima_alloc_and_copy_name_uuid(md, &new_dev_name, &new_dev_uuid, noio))
goto error;
combined_device_data = dm_ima_alloc(DM_IMA_DEVICE_BUF_LEN * 2, GFP_KERNEL, noio);
if (!combined_device_data)
goto error;
r = dm_ima_alloc_and_copy_capacity_str(md, &capacity_str, noio);
if (r)
goto error;
old_device_data = md->ima.active_table.device_metadata;
md->ima.active_table.device_metadata = new_device_data;
md->ima.active_table.device_metadata_len = strlen(new_device_data);
scnprintf(combined_device_data, DM_IMA_DEVICE_BUF_LEN * 2,
"%s%snew_name=%s,new_uuid=%s;%s", DM_IMA_VERSION_STR, old_device_data,
new_dev_name, new_dev_uuid, capacity_str);
dm_ima_measure_data("dm_device_rename", combined_device_data, strlen(combined_device_data),
noio);
goto exit;
error:
kfree(new_device_data);
exit:
kfree(capacity_str);
kfree(combined_device_data);
kfree(old_device_data);
kfree(new_dev_name);
kfree(new_dev_uuid);
}