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dm ima: measure data on device rename

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A given block device is identified by it's name and UUID.  However, both
these parameters can be renamed.  For an external attestation service to
correctly attest a given device, it needs to keep track of these rename
events.

Update the device data with the new values for IMA measurements.  Measure
both old and new device name/UUID parameters in the same IMA measurement
event, so that the old and the new values can be connected later.

Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Tushar Sugandhi 2021-07-12 17:49:02 -07:00 committed by Mike Snitzer
parent 99169b9383
commit 7d1d1df8ce
3 changed files with 53 additions and 0 deletions
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48
drivers/md/dm-ima.c
View File

@ -655,3 +655,51 @@ error2:
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, "%snew_name=%s,new_uuid=%s;%s",
old_device_data, new_dev_name, new_dev_uuid, capacity_str);
dm_ima_measure_data("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);
}

2
drivers/md/dm-ima.h
View File

@ -52,6 +52,7 @@ void dm_ima_measure_on_table_load(struct dm_table *table, unsigned int status_fl
void dm_ima_measure_on_device_resume(struct mapped_device *md, bool swap);
void dm_ima_measure_on_device_remove(struct mapped_device *md, bool remove_all);
void dm_ima_measure_on_table_clear(struct mapped_device *md, bool new_map);
void dm_ima_measure_on_device_rename(struct mapped_device *md);
#else
@ -60,6 +61,7 @@ static inline void dm_ima_measure_on_table_load(struct dm_table *table, unsigned
static inline void dm_ima_measure_on_device_resume(struct mapped_device *md, bool swap) {}
static inline void dm_ima_measure_on_device_remove(struct mapped_device *md, bool remove_all) {}
static inline void dm_ima_measure_on_table_clear(struct mapped_device *md, bool new_map) {}
static inline void dm_ima_measure_on_device_rename(struct mapped_device *md) {}
#endif /* CONFIG_IMA */

3
drivers/md/dm-ioctl.c
View File

@ -485,6 +485,9 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
param->flags |= DM_UEVENT_GENERATED_FLAG;
md = hc->md;
dm_ima_measure_on_device_rename(md);
up_write(&_hash_lock);
kfree(old_name);