diff options
Diffstat (limited to 'arch/powerpc/kernel/secvar-sysfs.c')
| -rw-r--r-- | arch/powerpc/kernel/secvar-sysfs.c | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/secvar-sysfs.c b/arch/powerpc/kernel/secvar-sysfs.c new file mode 100644 index 000000000000..a0a78aba2083 --- /dev/null +++ b/arch/powerpc/kernel/secvar-sysfs.c @@ -0,0 +1,248 @@ +// 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) +{ + ssize_t rc = 0; + struct device_node *node; + const char *format; + + node = of_find_compatible_node(NULL, NULL, "ibm,secvar-backend"); + if (!of_device_is_available(node)) + return -ENODEV; + + rc = of_property_read_string(node, "format", &format); + if (rc) + return rc; + + rc = sprintf(buf, "%s\n", format); + + of_node_put(node); + + return rc; +} + + +static ssize_t size_show(struct kobject *kobj, struct kobj_attribute *attr, + char *buf) +{ + uint64_t dsize; + int rc; + + rc = secvar_ops->get(kobj->name, strlen(kobj->name) + 1, NULL, &dsize); + if (rc) { + pr_err("Error retrieving %s variable size %d\n", kobj->name, + rc); + return rc; + } + + return sprintf(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) +{ + uint64_t dsize; + char *data; + int rc; + + rc = secvar_ops->get(kobj->name, strlen(kobj->name) + 1, NULL, &dsize); + if (rc) { + 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) +{ + + struct device_node *node; + u64 varsize; + int rc = 0; + + node = of_find_compatible_node(NULL, NULL, "ibm,secvar-backend"); + if (!of_device_is_available(node)) { + rc = -ENODEV; + goto out; + } + + rc = of_property_read_u64(node, "max-var-size", &varsize); + if (rc) + goto out; + + data_attr.size = varsize; + update_attr.size = varsize; + +out: + of_node_put(node); + + return rc; +} + +static int secvar_sysfs_load(void) +{ + char *name; + uint64_t namesize = 0; + struct kobject *kobj; + 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); + break; + } + + kobj = kzalloc(sizeof(*kobj), GFP_KERNEL); + if (!kobj) { + rc = -ENOMEM; + break; + } + + 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); + kobj = NULL; + } + + if (kobj) + kobject_uevent(kobj, KOBJ_ADD); + + } while (!rc); + + kfree(name); + return rc; +} + +static int secvar_sysfs_init(void) +{ + int rc; + + if (!secvar_ops) { + pr_warn("secvar: failed to retrieve secvar operations.\n"); + return -ENODEV; + } + + secvar_kobj = kobject_create_and_add("secvar", firmware_kobj); + if (!secvar_kobj) { + pr_err("secvar: Failed to create firmware kobj\n"); + return -ENOMEM; + } + + rc = sysfs_create_file(secvar_kobj, &format_attr.attr); + if (rc) { + kobject_put(secvar_kobj); + return -ENOMEM; + } + + secvar_kset = kset_create_and_add("vars", NULL, secvar_kobj); + if (!secvar_kset) { + pr_err("secvar: sysfs kobject registration failed.\n"); + kobject_put(secvar_kobj); + return -ENOMEM; + } + + rc = update_kobj_size(); + if (rc) { + pr_err("Cannot read the size of the attribute\n"); + return rc; + } + + secvar_sysfs_load(); + + return 0; +} + +late_initcall(secvar_sysfs_init); |