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1/*
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>
13#include <linux/slab.h>
14
15#include "internal.h"
16
17struct inode *efivarfs_get_inode(struct super_block *sb,
18 const struct inode *dir, int mode,
19 dev_t dev, bool is_removable)
20{
21 struct inode *inode = new_inode(sb);
22
23 if (inode) {
24 inode->i_ino = get_next_ino();
25 inode->i_mode = mode;
26 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
27 inode->i_flags = is_removable ? 0 : S_IMMUTABLE;
28 switch (mode & S_IFMT) {
29 case S_IFREG:
30 inode->i_fop = &efivarfs_file_operations;
31 break;
32 case S_IFDIR:
33 inode->i_op = &efivarfs_dir_inode_operations;
34 inode->i_fop = &simple_dir_operations;
35 inc_nlink(inode);
36 break;
37 }
38 }
39 return inode;
40}
41
42/*
43 * Return true if 'str' is a valid efivarfs filename of the form,
44 *
45 * VariableName-12345678-1234-1234-1234-1234567891bc
46 */
47bool efivarfs_valid_name(const char *str, int len)
48{
49 static const char dashes[EFI_VARIABLE_GUID_LEN] = {
50 [8] = 1, [13] = 1, [18] = 1, [23] = 1
51 };
52 const char *s = str + len - EFI_VARIABLE_GUID_LEN;
53 int i;
54
55 /*
56 * We need a GUID, plus at least one letter for the variable name,
57 * plus the '-' separator
58 */
59 if (len < EFI_VARIABLE_GUID_LEN + 2)
60 return false;
61
62 /* GUID must be preceded by a '-' */
63 if (*(s - 1) != '-')
64 return false;
65
66 /*
67 * Validate that 's' is of the correct format, e.g.
68 *
69 * 12345678-1234-1234-1234-123456789abc
70 */
71 for (i = 0; i < EFI_VARIABLE_GUID_LEN; i++) {
72 if (dashes[i]) {
73 if (*s++ != '-')
74 return false;
75 } else {
76 if (!isxdigit(*s++))
77 return false;
78 }
79 }
80
81 return true;
82}
83
84static void efivarfs_hex_to_guid(const char *str, efi_guid_t *guid)
85{
86 guid->b[0] = hex_to_bin(str[6]) << 4 | hex_to_bin(str[7]);
87 guid->b[1] = hex_to_bin(str[4]) << 4 | hex_to_bin(str[5]);
88 guid->b[2] = hex_to_bin(str[2]) << 4 | hex_to_bin(str[3]);
89 guid->b[3] = hex_to_bin(str[0]) << 4 | hex_to_bin(str[1]);
90 guid->b[4] = hex_to_bin(str[11]) << 4 | hex_to_bin(str[12]);
91 guid->b[5] = hex_to_bin(str[9]) << 4 | hex_to_bin(str[10]);
92 guid->b[6] = hex_to_bin(str[16]) << 4 | hex_to_bin(str[17]);
93 guid->b[7] = hex_to_bin(str[14]) << 4 | hex_to_bin(str[15]);
94 guid->b[8] = hex_to_bin(str[19]) << 4 | hex_to_bin(str[20]);
95 guid->b[9] = hex_to_bin(str[21]) << 4 | hex_to_bin(str[22]);
96 guid->b[10] = hex_to_bin(str[24]) << 4 | hex_to_bin(str[25]);
97 guid->b[11] = hex_to_bin(str[26]) << 4 | hex_to_bin(str[27]);
98 guid->b[12] = hex_to_bin(str[28]) << 4 | hex_to_bin(str[29]);
99 guid->b[13] = hex_to_bin(str[30]) << 4 | hex_to_bin(str[31]);
100 guid->b[14] = hex_to_bin(str[32]) << 4 | hex_to_bin(str[33]);
101 guid->b[15] = hex_to_bin(str[34]) << 4 | hex_to_bin(str[35]);
102}
103
104static int efivarfs_create(struct inode *dir, struct dentry *dentry,
105 umode_t mode, bool excl)
106{
107 struct inode *inode = NULL;
108 struct efivar_entry *var;
109 int namelen, i = 0, err = 0;
110 bool is_removable = false;
111
112 if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len))
113 return -EINVAL;
114
115 var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
116 if (!var)
117 return -ENOMEM;
118
119 /* length of the variable name itself: remove GUID and separator */
120 namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1;
121
122 efivarfs_hex_to_guid(dentry->d_name.name + namelen + 1,
123 &var->var.VendorGuid);
124
125 if (efivar_variable_is_removable(var->var.VendorGuid,
126 dentry->d_name.name, namelen))
127 is_removable = true;
128
129 inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0, is_removable);
130 if (!inode) {
131 err = -ENOMEM;
132 goto out;
133 }
134
135 for (i = 0; i < namelen; i++)
136 var->var.VariableName[i] = dentry->d_name.name[i];
137
138 var->var.VariableName[i] = '\0';
139
140 inode->i_private = var;
141
142 efivar_entry_add(var, &efivarfs_list);
143 d_instantiate(dentry, inode);
144 dget(dentry);
145out:
146 if (err) {
147 kfree(var);
148 if (inode)
149 iput(inode);
150 }
151 return err;
152}
153
154static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
155{
156 struct efivar_entry *var = d_inode(dentry)->i_private;
157
158 if (efivar_entry_delete(var))
159 return -EINVAL;
160
161 drop_nlink(d_inode(dentry));
162 dput(dentry);
163 return 0;
164};
165
166const struct inode_operations efivarfs_dir_inode_operations = {
167 .lookup = simple_lookup,
168 .unlink = efivarfs_unlink,
169 .create = efivarfs_create,
170};
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2012 Red Hat, Inc.
4 * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
5 */
6
7#include <linux/efi.h>
8#include <linux/fs.h>
9#include <linux/ctype.h>
10#include <linux/slab.h>
11#include <linux/uuid.h>
12
13#include "internal.h"
14
15struct inode *efivarfs_get_inode(struct super_block *sb,
16 const struct inode *dir, int mode,
17 dev_t dev, bool is_removable)
18{
19 struct inode *inode = new_inode(sb);
20
21 if (inode) {
22 inode->i_ino = get_next_ino();
23 inode->i_mode = mode;
24 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
25 inode->i_flags = is_removable ? 0 : S_IMMUTABLE;
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 const char *s = str + len - EFI_VARIABLE_GUID_LEN;
48
49 /*
50 * We need a GUID, plus at least one letter for the variable name,
51 * plus the '-' separator
52 */
53 if (len < EFI_VARIABLE_GUID_LEN + 2)
54 return false;
55
56 /* GUID must be preceded by a '-' */
57 if (*(s - 1) != '-')
58 return false;
59
60 /*
61 * Validate that 's' is of the correct format, e.g.
62 *
63 * 12345678-1234-1234-1234-123456789abc
64 */
65 return uuid_is_valid(s);
66}
67
68static int efivarfs_create(struct inode *dir, struct dentry *dentry,
69 umode_t mode, bool excl)
70{
71 struct inode *inode = NULL;
72 struct efivar_entry *var;
73 int namelen, i = 0, err = 0;
74 bool is_removable = false;
75
76 if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len))
77 return -EINVAL;
78
79 var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
80 if (!var)
81 return -ENOMEM;
82
83 /* length of the variable name itself: remove GUID and separator */
84 namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1;
85
86 err = guid_parse(dentry->d_name.name + namelen + 1, &var->var.VendorGuid);
87 if (err)
88 goto out;
89
90 if (efivar_variable_is_removable(var->var.VendorGuid,
91 dentry->d_name.name, namelen))
92 is_removable = true;
93
94 inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0, is_removable);
95 if (!inode) {
96 err = -ENOMEM;
97 goto out;
98 }
99
100 for (i = 0; i < namelen; i++)
101 var->var.VariableName[i] = dentry->d_name.name[i];
102
103 var->var.VariableName[i] = '\0';
104
105 inode->i_private = var;
106
107 err = efivar_entry_add(var, &efivarfs_list);
108 if (err)
109 goto out;
110
111 d_instantiate(dentry, inode);
112 dget(dentry);
113out:
114 if (err) {
115 kfree(var);
116 if (inode)
117 iput(inode);
118 }
119 return err;
120}
121
122static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
123{
124 struct efivar_entry *var = d_inode(dentry)->i_private;
125
126 if (efivar_entry_delete(var))
127 return -EINVAL;
128
129 drop_nlink(d_inode(dentry));
130 dput(dentry);
131 return 0;
132};
133
134const struct inode_operations efivarfs_dir_inode_operations = {
135 .lookup = simple_lookup,
136 .unlink = efivarfs_unlink,
137 .create = efivarfs_create,
138};