blob: 07ab49745e31c4c7ff945bbeb5b4cd67848ea3d3 [file] [log] [blame]
Matt Flemingd68772b2013-02-08 16:27:24 +00001/*
2 * Copyright (C) 2012 Red Hat, Inc.
3 * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 */
9
10#include <linux/efi.h>
11#include <linux/fs.h>
12#include <linux/ctype.h>
Linus Torvalds20b4fb42013-05-01 17:51:54 -070013#include <linux/slab.h>
Matt Flemingd68772b2013-02-08 16:27:24 +000014
15#include "internal.h"
16
17struct inode *efivarfs_get_inode(struct super_block *sb,
18 const struct inode *dir, int mode, dev_t dev)
19{
20 struct inode *inode = new_inode(sb);
21
22 if (inode) {
23 inode->i_ino = get_next_ino();
24 inode->i_mode = mode;
25 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
26 switch (mode & S_IFMT) {
27 case S_IFREG:
28 inode->i_fop = &efivarfs_file_operations;
29 break;
30 case S_IFDIR:
31 inode->i_op = &efivarfs_dir_inode_operations;
32 inode->i_fop = &simple_dir_operations;
33 inc_nlink(inode);
34 break;
35 }
36 }
37 return inode;
38}
39
40/*
41 * Return true if 'str' is a valid efivarfs filename of the form,
42 *
43 * VariableName-12345678-1234-1234-1234-1234567891bc
44 */
45bool efivarfs_valid_name(const char *str, int len)
46{
47 static const char dashes[EFI_VARIABLE_GUID_LEN] = {
48 [8] = 1, [13] = 1, [18] = 1, [23] = 1
49 };
50 const char *s = str + len - EFI_VARIABLE_GUID_LEN;
51 int i;
52
53 /*
54 * We need a GUID, plus at least one letter for the variable name,
55 * plus the '-' separator
56 */
57 if (len < EFI_VARIABLE_GUID_LEN + 2)
58 return false;
59
60 /* GUID must be preceded by a '-' */
61 if (*(s - 1) != '-')
62 return false;
63
64 /*
65 * Validate that 's' is of the correct format, e.g.
66 *
67 * 12345678-1234-1234-1234-123456789abc
68 */
69 for (i = 0; i < EFI_VARIABLE_GUID_LEN; i++) {
70 if (dashes[i]) {
71 if (*s++ != '-')
72 return false;
73 } else {
74 if (!isxdigit(*s++))
75 return false;
76 }
77 }
78
79 return true;
80}
81
82static void efivarfs_hex_to_guid(const char *str, efi_guid_t *guid)
83{
84 guid->b[0] = hex_to_bin(str[6]) << 4 | hex_to_bin(str[7]);
85 guid->b[1] = hex_to_bin(str[4]) << 4 | hex_to_bin(str[5]);
86 guid->b[2] = hex_to_bin(str[2]) << 4 | hex_to_bin(str[3]);
87 guid->b[3] = hex_to_bin(str[0]) << 4 | hex_to_bin(str[1]);
88 guid->b[4] = hex_to_bin(str[11]) << 4 | hex_to_bin(str[12]);
89 guid->b[5] = hex_to_bin(str[9]) << 4 | hex_to_bin(str[10]);
90 guid->b[6] = hex_to_bin(str[16]) << 4 | hex_to_bin(str[17]);
91 guid->b[7] = hex_to_bin(str[14]) << 4 | hex_to_bin(str[15]);
92 guid->b[8] = hex_to_bin(str[19]) << 4 | hex_to_bin(str[20]);
93 guid->b[9] = hex_to_bin(str[21]) << 4 | hex_to_bin(str[22]);
94 guid->b[10] = hex_to_bin(str[24]) << 4 | hex_to_bin(str[25]);
95 guid->b[11] = hex_to_bin(str[26]) << 4 | hex_to_bin(str[27]);
96 guid->b[12] = hex_to_bin(str[28]) << 4 | hex_to_bin(str[29]);
97 guid->b[13] = hex_to_bin(str[30]) << 4 | hex_to_bin(str[31]);
98 guid->b[14] = hex_to_bin(str[32]) << 4 | hex_to_bin(str[33]);
99 guid->b[15] = hex_to_bin(str[34]) << 4 | hex_to_bin(str[35]);
100}
101
102static int efivarfs_create(struct inode *dir, struct dentry *dentry,
103 umode_t mode, bool excl)
104{
105 struct inode *inode;
106 struct efivar_entry *var;
107 int namelen, i = 0, err = 0;
108
109 if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len))
110 return -EINVAL;
111
112 inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0);
113 if (!inode)
114 return -ENOMEM;
115
116 var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
117 if (!var) {
118 err = -ENOMEM;
119 goto out;
120 }
121
122 /* length of the variable name itself: remove GUID and separator */
123 namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1;
124
125 efivarfs_hex_to_guid(dentry->d_name.name + namelen + 1,
126 &var->var.VendorGuid);
127
128 for (i = 0; i < namelen; i++)
129 var->var.VariableName[i] = dentry->d_name.name[i];
130
131 var->var.VariableName[i] = '\0';
132
133 inode->i_private = var;
134
135 efivar_entry_add(var, &efivarfs_list);
136 d_instantiate(dentry, inode);
137 dget(dentry);
138out:
139 if (err) {
140 kfree(var);
141 iput(inode);
142 }
143 return err;
144}
145
146static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
147{
148 struct efivar_entry *var = dentry->d_inode->i_private;
149
150 if (efivar_entry_delete(var))
151 return -EINVAL;
152
153 drop_nlink(dentry->d_inode);
154 dput(dentry);
155 return 0;
156};
157
Matt Flemingd68772b2013-02-08 16:27:24 +0000158const struct inode_operations efivarfs_dir_inode_operations = {
Al Viro6e8cd2c2013-07-14 17:48:35 +0400159 .lookup = simple_lookup,
Matt Flemingd68772b2013-02-08 16:27:24 +0000160 .unlink = efivarfs_unlink,
161 .create = efivarfs_create,
162};