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|
// SPDX-License-Identifier: GPL-2.0+
/*
* EFI Test Driver for Runtime Services
*
* Copyright(C) 2012-2016 Canonical Ltd.
*
* This driver exports EFI runtime services interfaces into userspace, which
* allow to use and test UEFI runtime services provided by firmware.
*
*/
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/efi.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include "efi_test.h"
MODULE_AUTHOR("Ivan Hu <ivan.hu@canonical.com>");
MODULE_DESCRIPTION("EFI Test Driver");
MODULE_LICENSE("GPL");
/*
* Count the bytes in 'str', including the terminating NULL.
*
* Note this function returns the number of *bytes*, not the number of
* ucs2 characters.
*/
static inline size_t user_ucs2_strsize(efi_char16_t __user *str)
{
efi_char16_t *s = str, c;
size_t len;
if (!str)
return 0;
/* Include terminating NULL */
len = sizeof(efi_char16_t);
if (get_user(c, s++)) {
/* Can't read userspace memory for size */
return 0;
}
while (c != 0) {
if (get_user(c, s++)) {
/* Can't read userspace memory for size */
return 0;
}
len += sizeof(efi_char16_t);
}
return len;
}
/*
* Allocate a buffer and copy a ucs2 string from user space into it.
*/
static inline int
copy_ucs2_from_user_len(efi_char16_t **dst, efi_char16_t __user *src,
size_t len)
{
efi_char16_t *buf;
if (!src) {
*dst = NULL;
return 0;
}
if (!access_ok(src, 1))
return -EFAULT;
buf = memdup_user(src, len);
if (IS_ERR(buf)) {
*dst = NULL;
return PTR_ERR(buf);
}
*dst = buf;
return 0;
}
/*
* Count the bytes in 'str', including the terminating NULL.
*
* Just a wrap for user_ucs2_strsize
*/
static inline int
get_ucs2_strsize_from_user(efi_char16_t __user *src, size_t *len)
{
if (!access_ok(src, 1))
return -EFAULT;
*len = user_ucs2_strsize(src);
if (*len == 0)
return -EFAULT;
return 0;
}
/*
* Calculate the required buffer allocation size and copy a ucs2 string
* from user space into it.
*
* This function differs from copy_ucs2_from_user_len() because it
* calculates the size of the buffer to allocate by taking the length of
* the string 'src'.
*
* If a non-zero value is returned, the caller MUST NOT access 'dst'.
*
* It is the caller's responsibility to free 'dst'.
*/
static inline int
copy_ucs2_from_user(efi_char16_t **dst, efi_char16_t __user *src)
{
size_t len;
if (!access_ok(src, 1))
return -EFAULT;
len = user_ucs2_strsize(src);
if (len == 0)
return -EFAULT;
return copy_ucs2_from_user_len(dst, src, len);
}
/*
* Copy a ucs2 string to a user buffer.
*
* This function is a simple wrapper around copy_to_user() that does
* nothing if 'src' is NULL, which is useful for reducing the amount of
* NULL checking the caller has to do.
*
* 'len' specifies the number of bytes to copy.
*/
static inline int
copy_ucs2_to_user_len(efi_char16_t __user *dst, efi_char16_t *src, size_t len)
{
if (!src)
return 0;
if (!access_ok(dst, 1))
return -EFAULT;
return copy_to_user(dst, src, len);
}
static long efi_runtime_get_variable(unsigned long arg)
{
struct efi_getvariable __user *getvariable_user;
struct efi_getvariable getvariable;
unsigned long datasize = 0, prev_datasize, *dz;
efi_guid_t vendor_guid, *vd = NULL;
efi_status_t status;
efi_char16_t *name = NULL;
u32 attr, *at;
void *data = NULL;
int rv = 0;
getvariable_user = (struct efi_getvariable __user *)arg;
if (copy_from_user(&getvariable, getvariable_user,
sizeof(getvariable)))
return -EFAULT;
if (getvariable.data_size &&
get_user(datasize, getvariable.data_size))
return -EFAULT;
if (getvariable.vendor_guid) {
if (copy_from_user(&vendor_guid, getvariable.vendor_guid,
sizeof(vendor_guid)))
return -EFAULT;
vd = &vendor_guid;
}
if (getvariable.variable_name) {
rv = copy_ucs2_from_user(&name, getvariable.variable_name);
if (rv)
return rv;
}
at = getvariable.attributes ? &attr : NULL;
dz = getvariable.data_size ? &datasize : NULL;
if (getvariable.data_size && getvariable.data) {
data = kmalloc(datasize, GFP_KERNEL);
if (!data) {
kfree(name);
return -ENOMEM;
}
}
prev_datasize = datasize;
status = efi.get_variable(name, vd, at, dz, data);
kfree(name);
if (put_user(status, getvariable.status)) {
rv = -EFAULT;
goto out;
}
if (status != EFI_SUCCESS) {
if (status == EFI_BUFFER_TOO_SMALL) {
if (dz && put_user(datasize, getvariable.data_size)) {
rv = -EFAULT;
goto out;
}
}
rv = -EINVAL;
goto out;
}
if (prev_datasize < datasize) {
rv = -EINVAL;
goto out;
}
if (data) {
if (copy_to_user(getvariable.data, data, datasize)) {
rv = -EFAULT;
goto
|