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/kmemleak.h>
11#include <linux/slab.h>
12#include <linux/uuid.h>
13#include <linux/fileattr.h>
14
15#include "internal.h"
16
17static const struct inode_operations efivarfs_file_inode_operations;
18
19struct inode *efivarfs_get_inode(struct super_block *sb,
20 const struct inode *dir, int mode,
21 dev_t dev, bool is_removable)
22{
23 struct inode *inode = new_inode(sb);
24 struct efivarfs_fs_info *fsi = sb->s_fs_info;
25 struct efivarfs_mount_opts *opts = &fsi->mount_opts;
26
27 if (inode) {
28 inode->i_uid = opts->uid;
29 inode->i_gid = opts->gid;
30 inode->i_ino = get_next_ino();
31 inode->i_mode = mode;
32 simple_inode_init_ts(inode);
33 inode->i_flags = is_removable ? 0 : S_IMMUTABLE;
34 switch (mode & S_IFMT) {
35 case S_IFREG:
36 inode->i_op = &efivarfs_file_inode_operations;
37 inode->i_fop = &efivarfs_file_operations;
38 break;
39 case S_IFDIR:
40 inode->i_op = &efivarfs_dir_inode_operations;
41 inode->i_fop = &simple_dir_operations;
42 inc_nlink(inode);
43 break;
44 }
45 }
46 return inode;
47}
48
49/*
50 * Return true if 'str' is a valid efivarfs filename of the form,
51 *
52 * VariableName-12345678-1234-1234-1234-1234567891bc
53 */
54bool efivarfs_valid_name(const char *str, int len)
55{
56 const char *s = str + len - EFI_VARIABLE_GUID_LEN;
57
58 /*
59 * We need a GUID, plus at least one letter for the variable name,
60 * plus the '-' separator
61 */
62 if (len < EFI_VARIABLE_GUID_LEN + 2)
63 return false;
64
65 /* GUID must be preceded by a '-' */
66 if (*(s - 1) != '-')
67 return false;
68
69 /*
70 * Validate that 's' is of the correct format, e.g.
71 *
72 * 12345678-1234-1234-1234-123456789abc
73 */
74 return uuid_is_valid(uuid: s);
75}
76
77static int efivarfs_create(struct mnt_idmap *idmap, struct inode *dir,
78 struct dentry *dentry, umode_t mode, bool excl)
79{
80 struct inode *inode = NULL;
81 struct efivar_entry *var;
82 int namelen, i = 0, err = 0;
83 bool is_removable = false;
84
85 if (!efivarfs_valid_name(str: dentry->d_name.name, len: dentry->d_name.len))
86 return -EINVAL;
87
88 var = kzalloc(size: sizeof(struct efivar_entry), GFP_KERNEL);
89 if (!var)
90 return -ENOMEM;
91
92 /* length of the variable name itself: remove GUID and separator */
93 namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1;
94
95 err = guid_parse(uuid: dentry->d_name.name + namelen + 1, u: &var->var.VendorGuid);
96 if (err)
97 goto out;
98 if (guid_equal(u1: &var->var.VendorGuid, u2: &LINUX_EFI_RANDOM_SEED_TABLE_GUID)) {
99 err = -EPERM;
100 goto out;
101 }
102
103 if (efivar_variable_is_removable(vendor: var->var.VendorGuid,
104 name: dentry->d_name.name, len: namelen))
105 is_removable = true;
106
107 inode = efivarfs_get_inode(sb: dir->i_sb, dir, mode, dev: 0, is_removable);
108 if (!inode) {
109 err = -ENOMEM;
110 goto out;
111 }
112
113 for (i = 0; i < namelen; i++)
114 var->var.VariableName[i] = dentry->d_name.name[i];
115
116 var->var.VariableName[i] = '\0';
117
118 inode->i_private = var;
119 kmemleak_ignore(ptr: var);
120
121 err = efivar_entry_add(entry: var, head: &efivarfs_list);
122 if (err)
123 goto out;
124
125 d_instantiate(dentry, inode);
126 dget(dentry);
127out:
128 if (err) {
129 kfree(objp: var);
130 if (inode)
131 iput(inode);
132 }
133 return err;
134}
135
136static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
137{
138 struct efivar_entry *var = d_inode(dentry)->i_private;
139
140 if (efivar_entry_delete(entry: var))
141 return -EINVAL;
142
143 drop_nlink(inode: d_inode(dentry));
144 dput(dentry);
145 return 0;
146};
147
148const struct inode_operations efivarfs_dir_inode_operations = {
149 .lookup = simple_lookup,
150 .unlink = efivarfs_unlink,
151 .create = efivarfs_create,
152};
153
154static int
155efivarfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
156{
157 unsigned int i_flags;
158 unsigned int flags = 0;
159
160 i_flags = d_inode(dentry)->i_flags;
161 if (i_flags & S_IMMUTABLE)
162 flags |= FS_IMMUTABLE_FL;
163
164 fileattr_fill_flags(fa, flags);
165
166 return 0;
167}
168
169static int
170efivarfs_fileattr_set(struct mnt_idmap *idmap,
171 struct dentry *dentry, struct fileattr *fa)
172{
173 unsigned int i_flags = 0;
174
175 if (fileattr_has_fsx(fa))
176 return -EOPNOTSUPP;
177
178 if (fa->flags & ~FS_IMMUTABLE_FL)
179 return -EOPNOTSUPP;
180
181 if (fa->flags & FS_IMMUTABLE_FL)
182 i_flags |= S_IMMUTABLE;
183
184 inode_set_flags(inode: d_inode(dentry), flags: i_flags, S_IMMUTABLE);
185
186 return 0;
187}
188
189static const struct inode_operations efivarfs_file_inode_operations = {
190 .fileattr_get = efivarfs_fileattr_get,
191 .fileattr_set = efivarfs_fileattr_set,
192};
193

source code of linux/fs/efivarfs/inode.c