linux/drivers/acpi/bgrt.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* BGRT boot graphic support
* Authors: Matthew Garrett, Josh Triplett <josh@joshtriplett.org>
* Copyright 2012 Red Hat, Inc <mjg@redhat.com>
* Copyright 2012 Intel Corporation
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/sysfs.h>
#include <linux/efi-bgrt.h>
static void *bgrt_image;
static struct kobject *bgrt_kobj;
ACPI: bgrt: Fix CFI violation clang's Control Flow Integrity requires that every indirect call has a valid target, which is based on the type of the function pointer. The *_show() functions in this file are written as if they will be called from dev_attr_show(); however, they will be called from sysfs_kf_seq_show() because the files were created by sysfs_create_group() and the sysfs ops are based on kobj_sysfs_ops because of kobject_add_and_create(). Because the *_show() functions do not match the type of the show() member in struct kobj_attribute, there is a CFI violation. $ cat /sys/firmware/acpi/bgrt/{status,type,version,{x,y}offset}} 1 0 1 522 307 $ dmesg | grep "CFI failure" [ 267.761825] CFI failure (target: type_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8): [ 267.762246] CFI failure (target: xoffset_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8): [ 267.762584] CFI failure (target: status_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8): [ 267.762973] CFI failure (target: yoffset_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8): [ 267.763330] CFI failure (target: version_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8): Convert these functions to the type of the show() member in struct kobj_attribute so that there is no more CFI violation. Because these functions are all so similar, combine them into a macro. Fixes: d1ff4b1cdbab ("ACPI: Add support for exposing BGRT data") Link: https://github.com/ClangBuiltLinux/linux/issues/1406 Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2021-06-23 01:38:01 +00:00
#define BGRT_SHOW(_name, _member) \
static ssize_t _name##_show(struct kobject *kobj, \
struct kobj_attribute *attr, char *buf) \
{ \
return sysfs_emit(buf, "%d\n", bgrt_tab._member); \
ACPI: bgrt: Fix CFI violation clang's Control Flow Integrity requires that every indirect call has a valid target, which is based on the type of the function pointer. The *_show() functions in this file are written as if they will be called from dev_attr_show(); however, they will be called from sysfs_kf_seq_show() because the files were created by sysfs_create_group() and the sysfs ops are based on kobj_sysfs_ops because of kobject_add_and_create(). Because the *_show() functions do not match the type of the show() member in struct kobj_attribute, there is a CFI violation. $ cat /sys/firmware/acpi/bgrt/{status,type,version,{x,y}offset}} 1 0 1 522 307 $ dmesg | grep "CFI failure" [ 267.761825] CFI failure (target: type_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8): [ 267.762246] CFI failure (target: xoffset_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8): [ 267.762584] CFI failure (target: status_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8): [ 267.762973] CFI failure (target: yoffset_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8): [ 267.763330] CFI failure (target: version_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8): Convert these functions to the type of the show() member in struct kobj_attribute so that there is no more CFI violation. Because these functions are all so similar, combine them into a macro. Fixes: d1ff4b1cdbab ("ACPI: Add support for exposing BGRT data") Link: https://github.com/ClangBuiltLinux/linux/issues/1406 Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2021-06-23 01:38:01 +00:00
} \
struct kobj_attribute bgrt_attr_##_name = __ATTR_RO(_name)
BGRT_SHOW(version, version);
BGRT_SHOW(status, status);
BGRT_SHOW(type, image_type);
BGRT_SHOW(xoffset, image_offset_x);
BGRT_SHOW(yoffset, image_offset_y);
static ssize_t image_read(struct file *file, struct kobject *kobj,
struct bin_attribute *attr, char *buf, loff_t off, size_t count)
{
memcpy(buf, attr->private + off, count);
return count;
}
static BIN_ATTR_RO(image, 0); /* size gets filled in later */
static struct attribute *bgrt_attributes[] = {
ACPI: bgrt: Fix CFI violation clang's Control Flow Integrity requires that every indirect call has a valid target, which is based on the type of the function pointer. The *_show() functions in this file are written as if they will be called from dev_attr_show(); however, they will be called from sysfs_kf_seq_show() because the files were created by sysfs_create_group() and the sysfs ops are based on kobj_sysfs_ops because of kobject_add_and_create(). Because the *_show() functions do not match the type of the show() member in struct kobj_attribute, there is a CFI violation. $ cat /sys/firmware/acpi/bgrt/{status,type,version,{x,y}offset}} 1 0 1 522 307 $ dmesg | grep "CFI failure" [ 267.761825] CFI failure (target: type_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8): [ 267.762246] CFI failure (target: xoffset_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8): [ 267.762584] CFI failure (target: status_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8): [ 267.762973] CFI failure (target: yoffset_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8): [ 267.763330] CFI failure (target: version_show.d5e1ad21498a5fd14edbc5c320906598.cfi_jt+0x0/0x8): Convert these functions to the type of the show() member in struct kobj_attribute so that there is no more CFI violation. Because these functions are all so similar, combine them into a macro. Fixes: d1ff4b1cdbab ("ACPI: Add support for exposing BGRT data") Link: https://github.com/ClangBuiltLinux/linux/issues/1406 Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2021-06-23 01:38:01 +00:00
&bgrt_attr_version.attr,
&bgrt_attr_status.attr,
&bgrt_attr_type.attr,
&bgrt_attr_xoffset.attr,
&bgrt_attr_yoffset.attr,
NULL,
};
static struct bin_attribute *bgrt_bin_attributes[] = {
&bin_attr_image,
NULL,
};
static const struct attribute_group bgrt_attribute_group = {
.attrs = bgrt_attributes,
.bin_attrs = bgrt_bin_attributes,
};
int __init acpi_parse_bgrt(struct acpi_table_header *table)
{
efi_bgrt_init(table);
return 0;
}
static int __init bgrt_init(void)
{
int ret;
if (!bgrt_tab.image_address)
return -ENODEV;
bgrt_image = memremap(bgrt_tab.image_address, bgrt_image_size,
MEMREMAP_WB);
if (!bgrt_image) {
pr_notice("Ignoring BGRT: failed to map image memory\n");
return -ENOMEM;
}
bin_attr_image.private = bgrt_image;
bin_attr_image.size = bgrt_image_size;
bgrt_kobj = kobject_create_and_add("bgrt", acpi_kobj);
if (!bgrt_kobj) {
ret = -EINVAL;
goto out_memmap;
}
ret = sysfs_create_group(bgrt_kobj, &bgrt_attribute_group);
if (ret)
goto out_kobject;
return 0;
out_kobject:
kobject_put(bgrt_kobj);
out_memmap:
memunmap(bgrt_image);
return ret;
}
device_initcall(bgrt_init);