2022-01-26 16:12:37 -07:00
|
|
|
// SPDX-License-Identifier: GPL-2.0-only
|
|
|
|
/*
|
|
|
|
* Copyright (C) 2021 - Google LLC
|
|
|
|
* Author: David Brazdil <dbrazdil@google.com>
|
|
|
|
*
|
|
|
|
* Driver for Open Profile for DICE.
|
|
|
|
*
|
|
|
|
* This driver takes ownership of a reserved memory region containing data
|
|
|
|
* generated by the Open Profile for DICE measured boot protocol. The memory
|
|
|
|
* contents are not interpreted by the kernel but can be mapped into a userspace
|
|
|
|
* process via a misc device. Userspace can also request a wipe of the memory.
|
|
|
|
*
|
|
|
|
* Userspace can access the data with (w/o error handling):
|
|
|
|
*
|
|
|
|
* fd = open("/dev/open-dice0", O_RDWR);
|
|
|
|
* read(fd, &size, sizeof(unsigned long));
|
|
|
|
* data = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
|
|
|
|
* write(fd, NULL, 0); // wipe
|
|
|
|
* close(fd);
|
|
|
|
*/
|
|
|
|
|
|
|
|
#include <linux/io.h>
|
|
|
|
#include <linux/miscdevice.h>
|
|
|
|
#include <linux/mm.h>
|
|
|
|
#include <linux/module.h>
|
|
|
|
#include <linux/of_reserved_mem.h>
|
|
|
|
#include <linux/platform_device.h>
|
|
|
|
|
|
|
|
#define DRIVER_NAME "open-dice"
|
|
|
|
|
|
|
|
struct open_dice_drvdata {
|
|
|
|
struct mutex lock;
|
|
|
|
char name[16];
|
|
|
|
struct reserved_mem *rmem;
|
|
|
|
struct miscdevice misc;
|
|
|
|
};
|
|
|
|
|
|
|
|
static inline struct open_dice_drvdata *to_open_dice_drvdata(struct file *filp)
|
|
|
|
{
|
|
|
|
return container_of(filp->private_data, struct open_dice_drvdata, misc);
|
|
|
|
}
|
|
|
|
|
|
|
|
static int open_dice_wipe(struct open_dice_drvdata *drvdata)
|
|
|
|
{
|
|
|
|
void *kaddr;
|
|
|
|
|
|
|
|
mutex_lock(&drvdata->lock);
|
|
|
|
kaddr = devm_memremap(drvdata->misc.this_device, drvdata->rmem->base,
|
|
|
|
drvdata->rmem->size, MEMREMAP_WC);
|
|
|
|
if (IS_ERR(kaddr)) {
|
|
|
|
mutex_unlock(&drvdata->lock);
|
|
|
|
return PTR_ERR(kaddr);
|
|
|
|
}
|
|
|
|
|
|
|
|
memset(kaddr, 0, drvdata->rmem->size);
|
|
|
|
devm_memunmap(drvdata->misc.this_device, kaddr);
|
|
|
|
mutex_unlock(&drvdata->lock);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Copies the size of the reserved memory region to the user-provided buffer.
|
|
|
|
*/
|
|
|
|
static ssize_t open_dice_read(struct file *filp, char __user *ptr, size_t len,
|
|
|
|
loff_t *off)
|
|
|
|
{
|
|
|
|
unsigned long val = to_open_dice_drvdata(filp)->rmem->size;
|
|
|
|
|
|
|
|
return simple_read_from_buffer(ptr, len, off, &val, sizeof(val));
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Triggers a wipe of the reserved memory region. The user-provided pointer
|
|
|
|
* is never dereferenced.
|
|
|
|
*/
|
|
|
|
static ssize_t open_dice_write(struct file *filp, const char __user *ptr,
|
|
|
|
size_t len, loff_t *off)
|
|
|
|
{
|
|
|
|
if (open_dice_wipe(to_open_dice_drvdata(filp)))
|
|
|
|
return -EIO;
|
|
|
|
|
|
|
|
/* Consume the input buffer. */
|
|
|
|
return len;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Creates a mapping of the reserved memory region in user address space.
|
|
|
|
*/
|
|
|
|
static int open_dice_mmap(struct file *filp, struct vm_area_struct *vma)
|
|
|
|
{
|
|
|
|
struct open_dice_drvdata *drvdata = to_open_dice_drvdata(filp);
|
|
|
|
|
2023-01-02 09:08:56 -07:00
|
|
|
if (vma->vm_flags & VM_MAYSHARE) {
|
|
|
|
/* Do not allow userspace to modify the underlying data. */
|
|
|
|
if (vma->vm_flags & VM_WRITE)
|
|
|
|
return -EPERM;
|
|
|
|
/* Ensure userspace cannot acquire VM_WRITE later. */
|
2023-01-26 12:37:49 -07:00
|
|
|
vm_flags_clear(vma, VM_MAYWRITE);
|
2023-01-02 09:08:56 -07:00
|
|
|
}
|
2022-01-26 16:12:37 -07:00
|
|
|
|
|
|
|
/* Create write-combine mapping so all clients observe a wipe. */
|
|
|
|
vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
|
2023-01-26 12:37:49 -07:00
|
|
|
vm_flags_set(vma, VM_DONTCOPY | VM_DONTDUMP);
|
2022-01-26 16:12:37 -07:00
|
|
|
return vm_iomap_memory(vma, drvdata->rmem->base, drvdata->rmem->size);
|
|
|
|
}
|
|
|
|
|
|
|
|
static const struct file_operations open_dice_fops = {
|
|
|
|
.owner = THIS_MODULE,
|
|
|
|
.read = open_dice_read,
|
|
|
|
.write = open_dice_write,
|
|
|
|
.mmap = open_dice_mmap,
|
|
|
|
};
|
|
|
|
|
|
|
|
static int __init open_dice_probe(struct platform_device *pdev)
|
|
|
|
{
|
|
|
|
static unsigned int dev_idx;
|
|
|
|
struct device *dev = &pdev->dev;
|
|
|
|
struct reserved_mem *rmem;
|
|
|
|
struct open_dice_drvdata *drvdata;
|
|
|
|
int ret;
|
|
|
|
|
|
|
|
rmem = of_reserved_mem_lookup(dev->of_node);
|
|
|
|
if (!rmem) {
|
|
|
|
dev_err(dev, "failed to lookup reserved memory\n");
|
|
|
|
return -EINVAL;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (!rmem->size || (rmem->size > ULONG_MAX)) {
|
|
|
|
dev_err(dev, "invalid memory region size\n");
|
|
|
|
return -EINVAL;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (!PAGE_ALIGNED(rmem->base) || !PAGE_ALIGNED(rmem->size)) {
|
|
|
|
dev_err(dev, "memory region must be page-aligned\n");
|
|
|
|
return -EINVAL;
|
|
|
|
}
|
|
|
|
|
|
|
|
drvdata = devm_kmalloc(dev, sizeof(*drvdata), GFP_KERNEL);
|
|
|
|
if (!drvdata)
|
|
|
|
return -ENOMEM;
|
|
|
|
|
|
|
|
*drvdata = (struct open_dice_drvdata){
|
|
|
|
.rmem = rmem,
|
|
|
|
.misc = (struct miscdevice){
|
|
|
|
.parent = dev,
|
|
|
|
.name = drvdata->name,
|
|
|
|
.minor = MISC_DYNAMIC_MINOR,
|
|
|
|
.fops = &open_dice_fops,
|
|
|
|
.mode = 0600,
|
|
|
|
},
|
|
|
|
};
|
2024-01-26 08:24:10 -07:00
|
|
|
mutex_init(&drvdata->lock);
|
2022-01-26 16:12:37 -07:00
|
|
|
|
|
|
|
/* Index overflow check not needed, misc_register() will fail. */
|
|
|
|
snprintf(drvdata->name, sizeof(drvdata->name), DRIVER_NAME"%u", dev_idx++);
|
|
|
|
|
|
|
|
ret = misc_register(&drvdata->misc);
|
|
|
|
if (ret) {
|
|
|
|
dev_err(dev, "failed to register misc device '%s': %d\n",
|
|
|
|
drvdata->name, ret);
|
|
|
|
return ret;
|
|
|
|
}
|
|
|
|
|
|
|
|
platform_set_drvdata(pdev, drvdata);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
2024-02-21 02:53:50 -07:00
|
|
|
static void open_dice_remove(struct platform_device *pdev)
|
2022-01-26 16:12:37 -07:00
|
|
|
{
|
|
|
|
struct open_dice_drvdata *drvdata = platform_get_drvdata(pdev);
|
|
|
|
|
|
|
|
misc_deregister(&drvdata->misc);
|
|
|
|
}
|
|
|
|
|
|
|
|
static const struct of_device_id open_dice_of_match[] = {
|
|
|
|
{ .compatible = "google,open-dice" },
|
|
|
|
{},
|
|
|
|
};
|
|
|
|
|
|
|
|
static struct platform_driver open_dice_driver = {
|
2024-02-21 02:53:50 -07:00
|
|
|
.remove_new = open_dice_remove,
|
2022-01-26 16:12:37 -07:00
|
|
|
.driver = {
|
|
|
|
.name = DRIVER_NAME,
|
|
|
|
.of_match_table = open_dice_of_match,
|
|
|
|
},
|
|
|
|
};
|
|
|
|
|
|
|
|
static int __init open_dice_init(void)
|
|
|
|
{
|
|
|
|
int ret = platform_driver_probe(&open_dice_driver, open_dice_probe);
|
|
|
|
|
|
|
|
/* DICE regions are optional. Succeed even with zero instances. */
|
|
|
|
return (ret == -ENODEV) ? 0 : ret;
|
|
|
|
}
|
|
|
|
|
|
|
|
static void __exit open_dice_exit(void)
|
|
|
|
{
|
|
|
|
platform_driver_unregister(&open_dice_driver);
|
|
|
|
}
|
|
|
|
|
|
|
|
module_init(open_dice_init);
|
|
|
|
module_exit(open_dice_exit);
|
|
|
|
|
2024-06-03 13:32:29 -07:00
|
|
|
MODULE_DESCRIPTION("Driver for Open Profile for DICE.");
|
2022-01-26 16:12:37 -07:00
|
|
|
MODULE_LICENSE("GPL v2");
|
|
|
|
MODULE_AUTHOR("David Brazdil <dbrazdil@google.com>");
|