101 lines
2.6 KiB
C
101 lines
2.6 KiB
C
|
// SPDX-License-Identifier: GPL-2.0
|
||
|
|
/*
|
||
|
|
* Copyright (C) 2022 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
|
||
|
|
*
|
||
|
|
* The "Virtual Machine Generation ID" is exposed via ACPI and changes when a
|
||
|
|
* virtual machine forks or is cloned. This driver exists for shepherding that
|
||
|
|
* information to random.c.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <linux/kernel.h>
|
||
|
|
#include <linux/module.h>
|
||
|
|
#include <linux/acpi.h>
|
||
|
|
#include <linux/random.h>
|
||
|
|
|
||
|
|
ACPI_MODULE_NAME("vmgenid");
|
||
|
|
|
||
|
|
enum { VMGENID_SIZE = 16 };
|
||
|
|
|
||
|
|
struct vmgenid_state {
|
||
|
|
u8 *next_id;
|
||
|
|
u8 this_id[VMGENID_SIZE];
|
||
|
|
};
|
||
|
|
|
||
|
|
static int vmgenid_add(struct acpi_device *device)
|
||
|
|
{
|
||
|
|
struct acpi_buffer parsed = { ACPI_ALLOCATE_BUFFER };
|
||
|
|
struct vmgenid_state *state;
|
||
|
|
union acpi_object *obj;
|
||
|
|
phys_addr_t phys_addr;
|
||
|
|
acpi_status status;
|
||
|
|
int ret = 0;
|
||
|
|
|
||
|
|
state = devm_kmalloc(&device->dev, sizeof(*state), GFP_KERNEL);
|
||
|
|
if (!state)
|
||
|
|
return -ENOMEM;
|
||
|
|
|
||
|
|
status = acpi_evaluate_object(device->handle, "ADDR", NULL, &parsed);
|
||
|
|
if (ACPI_FAILURE(status)) {
|
||
|
|
ACPI_EXCEPTION((AE_INFO, status, "Evaluating ADDR"));
|
||
|
|
return -ENODEV;
|
||
|
|
}
|
||
|
|
obj = parsed.pointer;
|
||
|
|
if (!obj || obj->type != ACPI_TYPE_PACKAGE || obj->package.count != 2 ||
|
||
|
|
obj->package.elements[0].type != ACPI_TYPE_INTEGER ||
|
||
|
|
obj->package.elements[1].type != ACPI_TYPE_INTEGER) {
|
||
|
|
ret = -EINVAL;
|
||
|
|
goto out;
|
||
|
|
}
|
||
|
|
|
||
|
|
phys_addr = (obj->package.elements[0].integer.value << 0) |
|
||
|
|
(obj->package.elements[1].integer.value << 32);
|
||
|
|
state->next_id = devm_memremap(&device->dev, phys_addr, VMGENID_SIZE, MEMREMAP_WB);
|
||
|
|
if (IS_ERR(state->next_id)) {
|
||
|
|
ret = PTR_ERR(state->next_id);
|
||
|
|
goto out;
|
||
|
|
}
|
||
|
|
|
||
|
|
memcpy(state->this_id, state->next_id, sizeof(state->this_id));
|
||
|
|
add_device_randomness(state->this_id, sizeof(state->this_id));
|
||
|
|
|
||
|
|
device->driver_data = state;
|
||
|
|
|
||
|
|
out:
|
||
|
|
ACPI_FREE(parsed.pointer);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
static void vmgenid_notify(struct acpi_device *device, u32 event)
|
||
|
|
{
|
||
|
|
struct vmgenid_state *state = acpi_driver_data(device);
|
||
|
|
u8 old_id[VMGENID_SIZE];
|
||
|
|
|
||
|
|
memcpy(old_id, state->this_id, sizeof(old_id));
|
||
|
|
memcpy(state->this_id, state->next_id, sizeof(state->this_id));
|
||
|
|
if (!memcmp(old_id, state->this_id, sizeof(old_id)))
|
||
|
|
return;
|
||
|
|
add_vmfork_randomness(state->this_id, sizeof(state->this_id));
|
||
|
|
}
|
||
|
|
|
||
|
|
static const struct acpi_device_id vmgenid_ids[] = {
|
||
|
|
{ "VM_GEN_COUNTER", 0 },
|
||
|
|
{ }
|
||
|
|
};
|
||
|
|
|
||
|
|
static struct acpi_driver vmgenid_driver = {
|
||
|
|
.name = "vmgenid",
|
||
|
|
.ids = vmgenid_ids,
|
||
|
|
.owner = THIS_MODULE,
|
||
|
|
.ops = {
|
||
|
|
.add = vmgenid_add,
|
||
|
|
.notify = vmgenid_notify
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
module_acpi_driver(vmgenid_driver);
|
||
|
|
|
||
|
|
MODULE_DEVICE_TABLE(acpi, vmgenid_ids);
|
||
|
|
MODULE_DESCRIPTION("Virtual Machine Generation ID");
|
||
|
|
MODULE_LICENSE("GPL v2");
|
||
|
|
MODULE_AUTHOR("Jason A. Donenfeld <Jason@zx2c4.com>");
|