original development tree for Linux kernel GTP module; now long in mainline.
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/*
* Copyright (C) 2012 Red Hat, Inc.
* Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/efi.h>
#include <linux/fs.h>
#include <linux/ctype.h>
#include <linux/slab.h>
#include "internal.h"
struct inode *efivarfs_get_inode(struct super_block *sb,
const struct inode *dir, int mode, dev_t dev)
{
struct inode *inode = new_inode(sb);
if (inode) {
inode->i_ino = get_next_ino();
inode->i_mode = mode;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
switch (mode & S_IFMT) {
case S_IFREG:
inode->i_fop = &efivarfs_file_operations;
break;
case S_IFDIR:
inode->i_op = &efivarfs_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
inc_nlink(inode);
break;
}
}
return inode;
}
/*
* Return true if 'str' is a valid efivarfs filename of the form,
*
* VariableName-12345678-1234-1234-1234-1234567891bc
*/
bool efivarfs_valid_name(const char *str, int len)
{
static const char dashes[EFI_VARIABLE_GUID_LEN] = {
[8] = 1, [13] = 1, [18] = 1, [23] = 1
};
const char *s = str + len - EFI_VARIABLE_GUID_LEN;
int i;
/*
* We need a GUID, plus at least one letter for the variable name,
* plus the '-' separator
*/
if (len < EFI_VARIABLE_GUID_LEN + 2)
return false;
/* GUID must be preceded by a '-' */
if (*(s - 1) != '-')
return false;
/*
* Validate that 's' is of the correct format, e.g.
*
* 12345678-1234-1234-1234-123456789abc
*/
for (i = 0; i < EFI_VARIABLE_GUID_LEN; i++) {
if (dashes[i]) {
if (*s++ != '-')
return false;
} else {
if (!isxdigit(*s++))
return false;
}
}
return true;
}
static void efivarfs_hex_to_guid(const char *str, efi_guid_t *guid)
{
guid->b[0] = hex_to_bin(str[6]) << 4 | hex_to_bin(str[7]);
guid->b[1] = hex_to_bin(str[4]) << 4 | hex_to_bin(str[5]);
guid->b[2] = hex_to_bin(str[2]) << 4 | hex_to_bin(str[3]);
guid->b[3] = hex_to_bin(str[0]) << 4 | hex_to_bin(str[1]);
guid->b[4] = hex_to_bin(str[11]) << 4 | hex_to_bin(str[12]);
guid->b[5] = hex_to_bin(str[9]) << 4 | hex_to_bin(str[10]);
guid->b[6] = hex_to_bin(str[16]) << 4 | hex_to_bin(str[17]);
guid->b[7] = hex_to_bin(str[14]) << 4 | hex_to_bin(str[15]);
guid->b[8] = hex_to_bin(str[19]) << 4 | hex_to_bin(str[20]);
guid->b[9] = hex_to_bin(str[21]) << 4 | hex_to_bin(str[22]);
guid->b[10] = hex_to_bin(str[24]) << 4 | hex_to_bin(str[25]);
guid->b[11] = hex_to_bin(str[26]) << 4 | hex_to_bin(str[27]);
guid->b[12] = hex_to_bin(str[28]) << 4 | hex_to_bin(str[29]);
guid->b[13] = hex_to_bin(str[30]) << 4 | hex_to_bin(str[31]);
guid->b[14] = hex_to_bin(str[32]) << 4 | hex_to_bin(str[33]);
guid->b[15] = hex_to_bin(str[34]) << 4 | hex_to_bin(str[35]);
}
static int efivarfs_create(struct inode *dir, struct dentry *dentry,
umode_t mode, bool excl)
{
struct inode *inode;
struct efivar_entry *var;
int namelen, i = 0, err = 0;
if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len))
return -EINVAL;
inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0);
if (!inode)
return -ENOMEM;
var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
if (!var) {
err = -ENOMEM;
goto out;
}
/* length of the variable name itself: remove GUID and separator */
namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1;
efivarfs_hex_to_guid(dentry->d_name.name + namelen + 1,
&var->var.VendorGuid);
for (i = 0; i < namelen; i++)
var->var.VariableName[i] = dentry->d_name.name[i];
var->var.VariableName[i] = '\0';
inode->i_private = var;
efivar_entry_add(var, &efivarfs_list);
d_instantiate(dentry, inode);
dget(dentry);
out:
if (err) {
kfree(var);
iput(inode);
}
return err;
}
static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
{
struct efivar_entry *var = dentry->d_inode->i_private;
if (efivar_entry_delete(var))
return -EINVAL;
drop_nlink(dentry->d_inode);
dput(dentry);
return 0;
};
const struct inode_operations efivarfs_dir_inode_operations = {
.lookup = simple_lookup,
.unlink = efivarfs_unlink,
.create = efivarfs_create,
};