diff options
| -rw-r--r-- | MAINTAINERS | 1 | ||||
| -rw-r--r-- | drivers/virt/Kconfig | 11 | ||||
| -rw-r--r-- | drivers/virt/Makefile | 1 | ||||
| -rw-r--r-- | drivers/virt/vmgenid.c | 100 |
4 files changed, 113 insertions, 0 deletions
diff --git a/MAINTAINERS b/MAINTAINERS index 777cd6fa2b3d..a10997e15146 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -16211,6 +16211,7 @@ M: Jason A. Donenfeld <Jason@zx2c4.com> T: git https://git.kernel.org/pub/scm/linux/kernel/git/crng/random.git S: Maintained F: drivers/char/random.c +F: drivers/virt/vmgenid.c RAPIDIO SUBSYSTEM M: Matt Porter <mporter@kernel.crashing.org> diff --git a/drivers/virt/Kconfig b/drivers/virt/Kconfig index 8061e8ef449f..121b9293c737 100644 --- a/drivers/virt/Kconfig +++ b/drivers/virt/Kconfig @@ -13,6 +13,17 @@ menuconfig VIRT_DRIVERS if VIRT_DRIVERS +config VMGENID + tristate "Virtual Machine Generation ID driver" + default y + depends on ACPI + help + Say Y here to use the hypervisor-provided Virtual Machine Generation ID + to reseed the RNG when the VM is cloned. This is highly recommended if + you intend to do any rollback / cloning / snapshotting of VMs. + + Prefer Y to M so that this protection is activated very early. + config FSL_HV_MANAGER tristate "Freescale hypervisor management driver" depends on FSL_SOC diff --git a/drivers/virt/Makefile b/drivers/virt/Makefile index 3e272ea60cd9..108d0ffcc9aa 100644 --- a/drivers/virt/Makefile +++ b/drivers/virt/Makefile @@ -4,6 +4,7 @@ # obj-$(CONFIG_FSL_HV_MANAGER) += fsl_hypervisor.o +obj-$(CONFIG_VMGENID) += vmgenid.o obj-y += vboxguest/ obj-$(CONFIG_NITRO_ENCLAVES) += nitro_enclaves/ diff --git a/drivers/virt/vmgenid.c b/drivers/virt/vmgenid.c new file mode 100644 index 000000000000..0ae1a39f2e28 --- /dev/null +++ b/drivers/virt/vmgenid.c @@ -0,0 +1,100 @@ +// 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>"); |