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d68772b7 MF |
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> | |
20b4fb48 | 13 | #include <linux/slab.h> |
d68772b7 MF |
14 | |
15 | #include "internal.h" | |
16 | ||
17 | struct 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 | */ | |
45 | bool 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 | ||
82 | static 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 | ||
102 | static 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); | |
138 | out: | |
139 | if (err) { | |
140 | kfree(var); | |
141 | iput(inode); | |
142 | } | |
143 | return err; | |
144 | } | |
145 | ||
146 | static 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 | ||
d68772b7 | 158 | const struct inode_operations efivarfs_dir_inode_operations = { |
6e8cd2cb | 159 | .lookup = simple_lookup, |
d68772b7 MF |
160 | .unlink = efivarfs_unlink, |
161 | .create = efivarfs_create, | |
162 | }; |