1 // SPDX-License-Identifier: GPL-2.0+
3 * Copyright (C) 2019 IBM Corporation <nayna@linux.ibm.com>
5 * This code exposes secure variables to user via sysfs
8 #define pr_fmt(fmt) "secvar-sysfs: "fmt
10 #include <linux/slab.h>
11 #include <linux/compat.h>
12 #include <linux/string.h>
14 #include <asm/secvar.h>
16 #define NAME_MAX_SIZE 1024
18 static struct kobject *secvar_kobj;
19 static struct kset *secvar_kset;
21 static ssize_t format_show(struct kobject *kobj, struct kobj_attribute *attr,
25 struct device_node *node;
28 node = of_find_compatible_node(NULL, NULL, "ibm,secvar-backend");
29 if (!of_device_is_available(node)) {
34 rc = of_property_read_string(node, "format", &format);
38 rc = sprintf(buf, "%s\n", format);
47 static ssize_t size_show(struct kobject *kobj, struct kobj_attribute *attr,
53 rc = secvar_ops->get(kobj->name, strlen(kobj->name) + 1, NULL, &dsize);
55 pr_err("Error retrieving %s variable size %d\n", kobj->name,
60 return sprintf(buf, "%llu\n", dsize);
63 static ssize_t data_read(struct file *filep, struct kobject *kobj,
64 struct bin_attribute *attr, char *buf, loff_t off,
71 rc = secvar_ops->get(kobj->name, strlen(kobj->name) + 1, NULL, &dsize);
73 pr_err("Error getting %s variable size %d\n", kobj->name, rc);
76 pr_debug("dsize is %llu\n", dsize);
78 data = kzalloc(dsize, GFP_KERNEL);
82 rc = secvar_ops->get(kobj->name, strlen(kobj->name) + 1, data, &dsize);
84 pr_err("Error getting %s variable %d\n", kobj->name, rc);
88 rc = memory_read_from_buffer(buf, count, &off, data, dsize);
95 static ssize_t update_write(struct file *filep, struct kobject *kobj,
96 struct bin_attribute *attr, char *buf, loff_t off,
101 pr_debug("count is %ld\n", count);
102 rc = secvar_ops->set(kobj->name, strlen(kobj->name) + 1, buf, count);
104 pr_err("Error setting the %s variable %d\n", kobj->name, rc);
111 static struct kobj_attribute format_attr = __ATTR_RO(format);
113 static struct kobj_attribute size_attr = __ATTR_RO(size);
115 static struct bin_attribute data_attr = __BIN_ATTR_RO(data, 0);
117 static struct bin_attribute update_attr = __BIN_ATTR_WO(update, 0);
119 static struct bin_attribute *secvar_bin_attrs[] = {
125 static struct attribute *secvar_attrs[] = {
130 static const struct attribute_group secvar_attr_group = {
131 .attrs = secvar_attrs,
132 .bin_attrs = secvar_bin_attrs,
134 __ATTRIBUTE_GROUPS(secvar_attr);
136 static struct kobj_type secvar_ktype = {
137 .sysfs_ops = &kobj_sysfs_ops,
138 .default_groups = secvar_attr_groups,
141 static int update_kobj_size(void)
144 struct device_node *node;
148 node = of_find_compatible_node(NULL, NULL, "ibm,secvar-backend");
149 if (!of_device_is_available(node)) {
154 rc = of_property_read_u64(node, "max-var-size", &varsize);
158 data_attr.size = varsize;
159 update_attr.size = varsize;
167 static int secvar_sysfs_load(void)
170 uint64_t namesize = 0;
171 struct kobject *kobj;
174 name = kzalloc(NAME_MAX_SIZE, GFP_KERNEL);
179 rc = secvar_ops->get_next(name, &namesize, NAME_MAX_SIZE);
182 pr_err("error getting secvar from firmware %d\n",
187 kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
193 kobject_init(kobj, &secvar_ktype);
195 rc = kobject_add(kobj, &secvar_kset->kobj, "%s", name);
197 pr_warn("kobject_add error %d for attribute: %s\n", rc,
204 kobject_uevent(kobj, KOBJ_ADD);
212 static int secvar_sysfs_init(void)
217 pr_warn("secvar: failed to retrieve secvar operations.\n");
221 secvar_kobj = kobject_create_and_add("secvar", firmware_kobj);
223 pr_err("secvar: Failed to create firmware kobj\n");
227 rc = sysfs_create_file(secvar_kobj, &format_attr.attr);
229 kobject_put(secvar_kobj);
233 secvar_kset = kset_create_and_add("vars", NULL, secvar_kobj);
235 pr_err("secvar: sysfs kobject registration failed.\n");
236 kobject_put(secvar_kobj);
240 rc = update_kobj_size();
242 pr_err("Cannot read the size of the attribute\n");
251 late_initcall(secvar_sysfs_init);