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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, | |
ed8b0de5 PJ |
18 | const struct inode *dir, int mode, |
19 | dev_t dev, bool is_removable) | |
d68772b7 MF |
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; | |
ed8b0de5 | 27 | inode->i_flags = is_removable ? 0 : S_IMMUTABLE; |
d68772b7 MF |
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 | */ | |
47 | bool 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 | ||
84 | static 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 | ||
104 | static int efivarfs_create(struct inode *dir, struct dentry *dentry, | |
105 | umode_t mode, bool excl) | |
106 | { | |
ed8b0de5 | 107 | struct inode *inode = NULL; |
d68772b7 MF |
108 | struct efivar_entry *var; |
109 | int namelen, i = 0, err = 0; | |
ed8b0de5 | 110 | bool is_removable = false; |
d68772b7 MF |
111 | |
112 | if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len)) | |
113 | return -EINVAL; | |
114 | ||
d68772b7 | 115 | var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL); |
ed8b0de5 PJ |
116 | if (!var) |
117 | return -ENOMEM; | |
d68772b7 MF |
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 | ||
ed8b0de5 PJ |
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 | ||
d68772b7 MF |
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); | |
145 | out: | |
146 | if (err) { | |
147 | kfree(var); | |
ed8b0de5 PJ |
148 | if (inode) |
149 | iput(inode); | |
d68772b7 MF |
150 | } |
151 | return err; | |
152 | } | |
153 | ||
154 | static int efivarfs_unlink(struct inode *dir, struct dentry *dentry) | |
155 | { | |
2b0143b5 | 156 | struct efivar_entry *var = d_inode(dentry)->i_private; |
d68772b7 MF |
157 | |
158 | if (efivar_entry_delete(var)) | |
159 | return -EINVAL; | |
160 | ||
2b0143b5 | 161 | drop_nlink(d_inode(dentry)); |
d68772b7 MF |
162 | dput(dentry); |
163 | return 0; | |
164 | }; | |
165 | ||
d68772b7 | 166 | const struct inode_operations efivarfs_dir_inode_operations = { |
6e8cd2cb | 167 | .lookup = simple_lookup, |
d68772b7 MF |
168 | .unlink = efivarfs_unlink, |
169 | .create = efivarfs_create, | |
170 | }; |