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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, bool is_removable)
- {
- 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;
- inode->i_flags = is_removable ? 0 : S_IMMUTABLE;
- 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 = NULL;
- struct efivar_entry *var;
- int namelen, i = 0, err = 0;
- bool is_removable = false;
- if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len))
- return -EINVAL;
- var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
- if (!var)
- return -ENOMEM;
- /* 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);
- if (efivar_variable_is_removable(var->var.VendorGuid,
- dentry->d_name.name, namelen))
- is_removable = true;
- inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0, is_removable);
- if (!inode) {
- err = -ENOMEM;
- goto out;
- }
- 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);
- if (inode)
- iput(inode);
- }
- return err;
- }
- static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
- {
- struct efivar_entry *var = d_inode(dentry)->i_private;
- if (efivar_entry_delete(var))
- return -EINVAL;
- drop_nlink(d_inode(dentry));
- dput(dentry);
- return 0;
- };
- const struct inode_operations efivarfs_dir_inode_operations = {
- .lookup = simple_lookup,
- .unlink = efivarfs_unlink,
- .create = efivarfs_create,
- };
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