summaryrefslogtreecommitdiffstats
path: root/arch/powerpc/kernel/secvar-sysfs.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/powerpc/kernel/secvar-sysfs.c')
-rw-r--r--arch/powerpc/kernel/secvar-sysfs.c293
1 files changed, 293 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/secvar-sysfs.c b/arch/powerpc/kernel/secvar-sysfs.c
new file mode 100644
index 0000000000..eb3c053f32
--- /dev/null
+++ b/arch/powerpc/kernel/secvar-sysfs.c
@@ -0,0 +1,293 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019 IBM Corporation <nayna@linux.ibm.com>
+ *
+ * This code exposes secure variables to user via sysfs
+ */
+
+#define pr_fmt(fmt) "secvar-sysfs: "fmt
+
+#include <linux/slab.h>
+#include <linux/compat.h>
+#include <linux/string.h>
+#include <linux/of.h>
+#include <asm/secvar.h>
+
+#define NAME_MAX_SIZE 1024
+
+static struct kobject *secvar_kobj;
+static struct kset *secvar_kset;
+
+static ssize_t format_show(struct kobject *kobj, struct kobj_attribute *attr,
+ char *buf)
+{
+ char tmp[32];
+ ssize_t len = secvar_ops->format(tmp, sizeof(tmp));
+
+ if (len > 0)
+ return sysfs_emit(buf, "%s\n", tmp);
+ else if (len < 0)
+ pr_err("Error %zd reading format string\n", len);
+ else
+ pr_err("Got empty format string from backend\n");
+
+ return -EIO;
+}
+
+
+static ssize_t size_show(struct kobject *kobj, struct kobj_attribute *attr,
+ char *buf)
+{
+ u64 dsize;
+ int rc;
+
+ rc = secvar_ops->get(kobj->name, strlen(kobj->name) + 1, NULL, &dsize);
+ if (rc) {
+ if (rc != -ENOENT)
+ pr_err("Error retrieving %s variable size %d\n", kobj->name, rc);
+ return rc;
+ }
+
+ return sysfs_emit(buf, "%llu\n", dsize);
+}
+
+static ssize_t data_read(struct file *filep, struct kobject *kobj,
+ struct bin_attribute *attr, char *buf, loff_t off,
+ size_t count)
+{
+ char *data;
+ u64 dsize;
+ int rc;
+
+ rc = secvar_ops->get(kobj->name, strlen(kobj->name) + 1, NULL, &dsize);
+ if (rc) {
+ if (rc != -ENOENT)
+ pr_err("Error getting %s variable size %d\n", kobj->name, rc);
+ return rc;
+ }
+ pr_debug("dsize is %llu\n", dsize);
+
+ data = kzalloc(dsize, GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ rc = secvar_ops->get(kobj->name, strlen(kobj->name) + 1, data, &dsize);
+ if (rc) {
+ pr_err("Error getting %s variable %d\n", kobj->name, rc);
+ goto data_fail;
+ }
+
+ rc = memory_read_from_buffer(buf, count, &off, data, dsize);
+
+data_fail:
+ kfree(data);
+ return rc;
+}
+
+static ssize_t update_write(struct file *filep, struct kobject *kobj,
+ struct bin_attribute *attr, char *buf, loff_t off,
+ size_t count)
+{
+ int rc;
+
+ pr_debug("count is %ld\n", count);
+ rc = secvar_ops->set(kobj->name, strlen(kobj->name) + 1, buf, count);
+ if (rc) {
+ pr_err("Error setting the %s variable %d\n", kobj->name, rc);
+ return rc;
+ }
+
+ return count;
+}
+
+static struct kobj_attribute format_attr = __ATTR_RO(format);
+
+static struct kobj_attribute size_attr = __ATTR_RO(size);
+
+static struct bin_attribute data_attr = __BIN_ATTR_RO(data, 0);
+
+static struct bin_attribute update_attr = __BIN_ATTR_WO(update, 0);
+
+static struct bin_attribute *secvar_bin_attrs[] = {
+ &data_attr,
+ &update_attr,
+ NULL,
+};
+
+static struct attribute *secvar_attrs[] = {
+ &size_attr.attr,
+ NULL,
+};
+
+static const struct attribute_group secvar_attr_group = {
+ .attrs = secvar_attrs,
+ .bin_attrs = secvar_bin_attrs,
+};
+__ATTRIBUTE_GROUPS(secvar_attr);
+
+static struct kobj_type secvar_ktype = {
+ .sysfs_ops = &kobj_sysfs_ops,
+ .default_groups = secvar_attr_groups,
+};
+
+static int update_kobj_size(void)
+{
+
+ u64 varsize;
+ int rc = secvar_ops->max_size(&varsize);
+
+ if (rc)
+ return rc;
+
+ data_attr.size = varsize;
+ update_attr.size = varsize;
+
+ return 0;
+}
+
+static int secvar_sysfs_config(struct kobject *kobj)
+{
+ struct attribute_group config_group = {
+ .name = "config",
+ .attrs = (struct attribute **)secvar_ops->config_attrs,
+ };
+
+ if (secvar_ops->config_attrs)
+ return sysfs_create_group(kobj, &config_group);
+
+ return 0;
+}
+
+static int add_var(const char *name)
+{
+ struct kobject *kobj;
+ int rc;
+
+ kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
+ if (!kobj)
+ return -ENOMEM;
+
+ kobject_init(kobj, &secvar_ktype);
+
+ rc = kobject_add(kobj, &secvar_kset->kobj, "%s", name);
+ if (rc) {
+ pr_warn("kobject_add error %d for attribute: %s\n", rc,
+ name);
+ kobject_put(kobj);
+ return rc;
+ }
+
+ kobject_uevent(kobj, KOBJ_ADD);
+ return 0;
+}
+
+static int secvar_sysfs_load(void)
+{
+ u64 namesize = 0;
+ char *name;
+ int rc;
+
+ name = kzalloc(NAME_MAX_SIZE, GFP_KERNEL);
+ if (!name)
+ return -ENOMEM;
+
+ do {
+ rc = secvar_ops->get_next(name, &namesize, NAME_MAX_SIZE);
+ if (rc) {
+ if (rc != -ENOENT)
+ pr_err("error getting secvar from firmware %d\n", rc);
+ else
+ rc = 0;
+
+ break;
+ }
+
+ rc = add_var(name);
+ } while (!rc);
+
+ kfree(name);
+ return rc;
+}
+
+static int secvar_sysfs_load_static(void)
+{
+ const char * const *name_ptr = secvar_ops->var_names;
+ int rc;
+
+ while (*name_ptr) {
+ rc = add_var(*name_ptr);
+ if (rc)
+ return rc;
+ name_ptr++;
+ }
+
+ return 0;
+}
+
+static int secvar_sysfs_init(void)
+{
+ u64 max_size;
+ int rc;
+
+ if (!secvar_ops) {
+ pr_warn("Failed to retrieve secvar operations\n");
+ return -ENODEV;
+ }
+
+ secvar_kobj = kobject_create_and_add("secvar", firmware_kobj);
+ if (!secvar_kobj) {
+ pr_err("Failed to create firmware kobj\n");
+ return -ENOMEM;
+ }
+
+ rc = sysfs_create_file(secvar_kobj, &format_attr.attr);
+ if (rc) {
+ pr_err("Failed to create format object\n");
+ rc = -ENOMEM;
+ goto err;
+ }
+
+ secvar_kset = kset_create_and_add("vars", NULL, secvar_kobj);
+ if (!secvar_kset) {
+ pr_err("sysfs kobject registration failed\n");
+ rc = -ENOMEM;
+ goto err;
+ }
+
+ rc = update_kobj_size();
+ if (rc) {
+ pr_err("Cannot read the size of the attribute\n");
+ goto err;
+ }
+
+ rc = secvar_sysfs_config(secvar_kobj);
+ if (rc) {
+ pr_err("Failed to create config directory\n");
+ goto err;
+ }
+
+ if (secvar_ops->get_next)
+ rc = secvar_sysfs_load();
+ else
+ rc = secvar_sysfs_load_static();
+
+ if (rc) {
+ pr_err("Failed to create variable attributes\n");
+ goto err;
+ }
+
+ // Due to sysfs limitations, we will only ever get a write buffer of
+ // up to 1 page in size. Print a warning if this is potentially going
+ // to cause problems, so that the user is aware.
+ secvar_ops->max_size(&max_size);
+ if (max_size > PAGE_SIZE)
+ pr_warn_ratelimited("PAGE_SIZE (%lu) is smaller than maximum object size (%llu), writes are limited to PAGE_SIZE\n",
+ PAGE_SIZE, max_size);
+
+ return 0;
+err:
+ kobject_put(secvar_kobj);
+ return rc;
+}
+
+late_initcall(secvar_sysfs_init);