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OpenCloudOS-Kernel/drivers/md/dm-ima.c

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// 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 = dm_table_get_num_targets(table);
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);
if (!ti)
goto error;
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);
}
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