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linux/drivers/xen/efi.c
Demi Marie Obenour c0fecaa44d efi: Apply allowlist to EFI configuration tables when running under Xen 
As it turns out, Xen does not guarantee that EFI boot services data
regions in memory are preserved, which means that EFI configuration
tables pointing into such memory regions may be corrupted before the
dom0 OS has had a chance to inspect them.

This is causing problems for Qubes OS when it attempts to perform system
firmware updates, which requires that the contents of the EFI System
Resource Table are valid when the fwupd userspace program runs.

However, other configuration tables such as the memory attributes table
or the runtime properties table are equally affected, and so we need a
comprehensive workaround that works for any table type.

So when running under Xen, check the EFI memory descriptor covering the
start of the table, and disregard the table if it does not reside in
memory that is preserved by Xen.

Co-developed-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Tested-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2023-01-23 11:33:24 +01:00

356 lines
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C
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// SPDX-License-Identifier: GPL-2.0-only
/*
* EFI support for Xen.
*
* Copyright (C) 1999 VA Linux Systems
* Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
* Copyright (C) 1999-2002 Hewlett-Packard Co.
* David Mosberger-Tang <davidm@hpl.hp.com>
* Stephane Eranian <eranian@hpl.hp.com>
* Copyright (C) 2005-2008 Intel Co.
* Fenghua Yu <fenghua.yu@intel.com>
* Bibo Mao <bibo.mao@intel.com>
* Chandramouli Narayanan <mouli@linux.intel.com>
* Huang Ying <ying.huang@intel.com>
* Copyright (C) 2011 Novell Co.
* Jan Beulich <JBeulich@suse.com>
* Copyright (C) 2011-2012 Oracle Co.
* Liang Tang <liang.tang@oracle.com>
* Copyright (c) 2014 Oracle Co., Daniel Kiper
*/
#include <linux/bug.h>
#include <linux/efi.h>
#include <linux/init.h>
#include <linux/string.h>
#include <xen/interface/xen.h>
#include <xen/interface/platform.h>
#include <xen/page.h>
#include <xen/xen.h>
#include <xen/xen-ops.h>
#include <asm/page.h>
#include <asm/xen/hypercall.h>
#define INIT_EFI_OP(name) \
{.cmd = XENPF_efi_runtime_call, \
.u.efi_runtime_call.function = XEN_EFI_##name, \
.u.efi_runtime_call.misc = 0}
#define efi_data(op) (op.u.efi_runtime_call)
static efi_status_t xen_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
{
struct xen_platform_op op = INIT_EFI_OP(get_time);
if (HYPERVISOR_platform_op(&op) < 0)
return EFI_UNSUPPORTED;
if (tm) {
BUILD_BUG_ON(sizeof(*tm) != sizeof(efi_data(op).u.get_time.time));
memcpy(tm, &efi_data(op).u.get_time.time, sizeof(*tm));
}
if (tc) {
tc->resolution = efi_data(op).u.get_time.resolution;
tc->accuracy = efi_data(op).u.get_time.accuracy;
tc->sets_to_zero = !!(efi_data(op).misc &
XEN_EFI_GET_TIME_SET_CLEARS_NS);
}
return efi_data(op).status;
}
static efi_status_t xen_efi_set_time(efi_time_t *tm)
{
struct xen_platform_op op = INIT_EFI_OP(set_time);
BUILD_BUG_ON(sizeof(*tm) != sizeof(efi_data(op).u.set_time));
memcpy(&efi_data(op).u.set_time, tm, sizeof(*tm));
if (HYPERVISOR_platform_op(&op) < 0)
return EFI_UNSUPPORTED;
return efi_data(op).status;
}
static efi_status_t xen_efi_get_wakeup_time(efi_bool_t *enabled,
efi_bool_t *pending,
efi_time_t *tm)
{
struct xen_platform_op op = INIT_EFI_OP(get_wakeup_time);
if (HYPERVISOR_platform_op(&op) < 0)
return EFI_UNSUPPORTED;
if (tm) {
BUILD_BUG_ON(sizeof(*tm) != sizeof(efi_data(op).u.get_wakeup_time));
memcpy(tm, &efi_data(op).u.get_wakeup_time, sizeof(*tm));
}
if (enabled)
*enabled = !!(efi_data(op).misc & XEN_EFI_GET_WAKEUP_TIME_ENABLED);
if (pending)
*pending = !!(efi_data(op).misc & XEN_EFI_GET_WAKEUP_TIME_PENDING);
return efi_data(op).status;
}
static efi_status_t xen_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm)
{
struct xen_platform_op op = INIT_EFI_OP(set_wakeup_time);
BUILD_BUG_ON(sizeof(*tm) != sizeof(efi_data(op).u.set_wakeup_time));
if (enabled)
efi_data(op).misc = XEN_EFI_SET_WAKEUP_TIME_ENABLE;
if (tm)
memcpy(&efi_data(op).u.set_wakeup_time, tm, sizeof(*tm));
else
efi_data(op).misc |= XEN_EFI_SET_WAKEUP_TIME_ENABLE_ONLY;
if (HYPERVISOR_platform_op(&op) < 0)
return EFI_UNSUPPORTED;
return efi_data(op).status;
}
static efi_status_t xen_efi_get_variable(efi_char16_t *name, efi_guid_t *vendor,
u32 *attr, unsigned long *data_size,
void *data)
{
struct xen_platform_op op = INIT_EFI_OP(get_variable);
set_xen_guest_handle(efi_data(op).u.get_variable.name, name);
BUILD_BUG_ON(sizeof(*vendor) !=
sizeof(efi_data(op).u.get_variable.vendor_guid));
memcpy(&efi_data(op).u.get_variable.vendor_guid, vendor, sizeof(*vendor));
efi_data(op).u.get_variable.size = *data_size;
set_xen_guest_handle(efi_data(op).u.get_variable.data, data);
if (HYPERVISOR_platform_op(&op) < 0)
return EFI_UNSUPPORTED;
*data_size = efi_data(op).u.get_variable.size;
if (attr)
*attr = efi_data(op).misc;
return efi_data(op).status;
}
static efi_status_t xen_efi_get_next_variable(unsigned long *name_size,
efi_char16_t *name,
efi_guid_t *vendor)
{
struct xen_platform_op op = INIT_EFI_OP(get_next_variable_name);
efi_data(op).u.get_next_variable_name.size = *name_size;
set_xen_guest_handle(efi_data(op).u.get_next_variable_name.name, name);
BUILD_BUG_ON(sizeof(*vendor) !=
sizeof(efi_data(op).u.get_next_variable_name.vendor_guid));
memcpy(&efi_data(op).u.get_next_variable_name.vendor_guid, vendor,
sizeof(*vendor));
if (HYPERVISOR_platform_op(&op) < 0)
return EFI_UNSUPPORTED;
*name_size = efi_data(op).u.get_next_variable_name.size;
memcpy(vendor, &efi_data(op).u.get_next_variable_name.vendor_guid,
sizeof(*vendor));
return efi_data(op).status;
}
static efi_status_t xen_efi_set_variable(efi_char16_t *name, efi_guid_t *vendor,
u32 attr, unsigned long data_size,
void *data)
{
struct xen_platform_op op = INIT_EFI_OP(set_variable);
set_xen_guest_handle(efi_data(op).u.set_variable.name, name);
efi_data(op).misc = attr;
BUILD_BUG_ON(sizeof(*vendor) !=
sizeof(efi_data(op).u.set_variable.vendor_guid));
memcpy(&efi_data(op).u.set_variable.vendor_guid, vendor, sizeof(*vendor));
efi_data(op).u.set_variable.size = data_size;
set_xen_guest_handle(efi_data(op).u.set_variable.data, data);
if (HYPERVISOR_platform_op(&op) < 0)
return EFI_UNSUPPORTED;
return efi_data(op).status;
}
static efi_status_t xen_efi_query_variable_info(u32 attr, u64 *storage_space,
u64 *remaining_space,
u64 *max_variable_size)
{
struct xen_platform_op op = INIT_EFI_OP(query_variable_info);
if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
return EFI_UNSUPPORTED;
efi_data(op).u.query_variable_info.attr = attr;
if (HYPERVISOR_platform_op(&op) < 0)
return EFI_UNSUPPORTED;
*storage_space = efi_data(op).u.query_variable_info.max_store_size;
*remaining_space = efi_data(op).u.query_variable_info.remain_store_size;
*max_variable_size = efi_data(op).u.query_variable_info.max_size;
return efi_data(op).status;
}
static efi_status_t xen_efi_get_next_high_mono_count(u32 *count)
{
struct xen_platform_op op = INIT_EFI_OP(get_next_high_monotonic_count);
if (HYPERVISOR_platform_op(&op) < 0)
return EFI_UNSUPPORTED;
*count = efi_data(op).misc;
return efi_data(op).status;
}
static efi_status_t xen_efi_update_capsule(efi_capsule_header_t **capsules,
unsigned long count, unsigned long sg_list)
{
struct xen_platform_op op = INIT_EFI_OP(update_capsule);
if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
return EFI_UNSUPPORTED;
set_xen_guest_handle(efi_data(op).u.update_capsule.capsule_header_array,
capsules);
efi_data(op).u.update_capsule.capsule_count = count;
efi_data(op).u.update_capsule.sg_list = sg_list;
if (HYPERVISOR_platform_op(&op) < 0)
return EFI_UNSUPPORTED;
return efi_data(op).status;
}
static efi_status_t xen_efi_query_capsule_caps(efi_capsule_header_t **capsules,
unsigned long count, u64 *max_size, int *reset_type)
{
struct xen_platform_op op = INIT_EFI_OP(query_capsule_capabilities);
if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
return EFI_UNSUPPORTED;
set_xen_guest_handle(efi_data(op).u.query_capsule_capabilities.capsule_header_array,
capsules);
efi_data(op).u.query_capsule_capabilities.capsule_count = count;
if (HYPERVISOR_platform_op(&op) < 0)
return EFI_UNSUPPORTED;
*max_size = efi_data(op).u.query_capsule_capabilities.max_capsule_size;
*reset_type = efi_data(op).u.query_capsule_capabilities.reset_type;
return efi_data(op).status;
}
static void xen_efi_reset_system(int reset_type, efi_status_t status,
unsigned long data_size, efi_char16_t *data)
{
switch (reset_type) {
case EFI_RESET_COLD:
case EFI_RESET_WARM:
xen_reboot(SHUTDOWN_reboot);
break;
case EFI_RESET_SHUTDOWN:
xen_reboot(SHUTDOWN_poweroff);
break;
default:
BUG();
}
}
/*
* Set XEN EFI runtime services function pointers. Other fields of struct efi,
* e.g. efi.systab, will be set like normal EFI.
*/
void __init xen_efi_runtime_setup(void)
{
efi.get_time = xen_efi_get_time;
efi.set_time = xen_efi_set_time;
efi.get_wakeup_time = xen_efi_get_wakeup_time;
efi.set_wakeup_time = xen_efi_set_wakeup_time;
efi.get_variable = xen_efi_get_variable;
efi.get_next_variable = xen_efi_get_next_variable;
efi.set_variable = xen_efi_set_variable;
efi.set_variable_nonblocking = xen_efi_set_variable;
efi.query_variable_info = xen_efi_query_variable_info;
efi.query_variable_info_nonblocking = xen_efi_query_variable_info;
efi.update_capsule = xen_efi_update_capsule;
efi.query_capsule_caps = xen_efi_query_capsule_caps;
efi.get_next_high_mono_count = xen_efi_get_next_high_mono_count;
efi.reset_system = xen_efi_reset_system;
}
int efi_mem_desc_lookup(u64 phys_addr, efi_memory_desc_t *out_md)
{
static_assert(XEN_PAGE_SHIFT == EFI_PAGE_SHIFT,
"Mismatch between EFI_PAGE_SHIFT and XEN_PAGE_SHIFT");
struct xen_platform_op op;
union xenpf_efi_info *info = &op.u.firmware_info.u.efi_info;
int rc;
if (!efi_enabled(EFI_PARAVIRT) || efi_enabled(EFI_MEMMAP))
return __efi_mem_desc_lookup(phys_addr, out_md);
phys_addr &= ~(u64)(EFI_PAGE_SIZE - 1);
op = (struct xen_platform_op) {
.cmd = XENPF_firmware_info,
.u.firmware_info = {
.type = XEN_FW_EFI_INFO,
.index = XEN_FW_EFI_MEM_INFO,
.u.efi_info.mem.addr = phys_addr,
.u.efi_info.mem.size = U64_MAX - phys_addr,
},
};
rc = HYPERVISOR_platform_op(&op);
if (rc) {
pr_warn("Failed to lookup header 0x%llx in Xen memory map: error %d\n",
phys_addr, rc);
}
out_md->phys_addr = info->mem.addr;
out_md->num_pages = info->mem.size >> EFI_PAGE_SHIFT;
out_md->type = info->mem.type;
out_md->attribute = info->mem.attr;
return 0;
}
bool __init xen_efi_config_table_is_usable(const efi_guid_t *guid,
unsigned long table)
{
efi_memory_desc_t md;
int rc;
if (!efi_enabled(EFI_PARAVIRT))
return true;
rc = efi_mem_desc_lookup(table, &md);
if (rc)
return false;
switch (md.type) {
case EFI_RUNTIME_SERVICES_CODE:
case EFI_RUNTIME_SERVICES_DATA:
case EFI_ACPI_RECLAIM_MEMORY:
case EFI_ACPI_MEMORY_NVS:
case EFI_RESERVED_TYPE:
return true;
default:
return false;
}
}
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