/*
 * Originally from efivars.c,
 *
 * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
 * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
 *
 * This code takes all variables accessible from EFI runtime and
 *  exports them via sysfs
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Changelog:
 *
 *  17 May 2004 - Matt Domsch <Matt_Domsch@dell.com>
 *   remove check for efi_enabled in exit
 *   add MODULE_VERSION
 *
 *  26 Apr 2004 - Matt Domsch <Matt_Domsch@dell.com>
 *   minor bug fixes
 *
 *  21 Apr 2004 - Matt Tolentino <matthew.e.tolentino@intel.com)
 *   converted driver to export variable information via sysfs
 *   and moved to drivers/firmware directory
 *   bumped revision number to v0.07 to reflect conversion & move
 *
 *  10 Dec 2002 - Matt Domsch <Matt_Domsch@dell.com>
 *   fix locking per Peter Chubb's findings
 *
 *  25 Mar 2002 - Matt Domsch <Matt_Domsch@dell.com>
 *   move uuid_unparse() to include/asm-ia64/efi.h:efi_guid_to_str()
 *
 *  12 Feb 2002 - Matt Domsch <Matt_Domsch@dell.com>
 *   use list_for_each_safe when deleting vars.
 *   remove ifdef CONFIG_SMP around include <linux/smp.h>
 *   v0.04 release to linux-ia64@linuxia64.org
 *
 *  20 April 2001 - Matt Domsch <Matt_Domsch@dell.com>
 *   Moved vars from /proc/efi to /proc/efi/vars, and made
 *   efi.c own the /proc/efi directory.
 *   v0.03 release to linux-ia64@linuxia64.org
 *
 *  26 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
 *   At the request of Stephane, moved ownership of /proc/efi
 *   to efi.c, and now efivars lives under /proc/efi/vars.
 *
 *  12 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
 *   Feedback received from Stephane Eranian incorporated.
 *   efivar_write() checks copy_from_user() return value.
 *   efivar_read/write() returns proper errno.
 *   v0.02 release to linux-ia64@linuxia64.org
 *
 *  26 February 2001 - Matt Domsch <Matt_Domsch@dell.com>
 *   v0.01 release to linux-ia64@linuxia64.org
 */

#include <linux/efi.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/ucs2_string.h>
#include <linux/compat.h>

#define EFIVARS_VERSION "0.08"
#define EFIVARS_DATE "2004-May-17"

MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");
MODULE_DESCRIPTION("sysfs interface to EFI Variables");
MODULE_LICENSE("GPL");
MODULE_VERSION(EFIVARS_VERSION);
MODULE_ALIAS("platform:efivars");

LIST_HEAD(efivar_sysfs_list);
EXPORT_SYMBOL_GPL(efivar_sysfs_list);

static struct kset *efivars_kset;

static struct bin_attribute *efivars_new_var;
static struct bin_attribute *efivars_del_var;

struct compat_efi_variable {
        efi_char16_t  VariableName[EFI_VAR_NAME_LEN/sizeof(efi_char16_t)];
        efi_guid_t    VendorGuid;
        __u32         DataSize;
        __u8          Data[1024];
        __u32         Status;
        __u32         Attributes;
} __packed;

struct efivar_attribute {
        struct attribute attr;
        ssize_t (*show) (struct efivar_entry *entry, char *buf);
        ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
};

#define EFIVAR_ATTR(_name, _mode, _show, _store) \
struct efivar_attribute efivar_attr_##_name = { \
        .attr = {.name = __stringify(_name), .mode = _mode}, \
        .show = _show, \
        .store = _store, \
};

#define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
#define to_efivar_entry(obj)  container_of(obj, struct efivar_entry, kobj)

/*
 * Prototype for sysfs creation function
 */
static int
efivar_create_sysfs_entry(struct efivar_entry *new_var);

static ssize_t
efivar_guid_read(struct efivar_entry *entry, char *buf)
{
        struct efi_variable *var = &entry->var;
        char *str = buf;

        if (!entry || !buf)
                return 0;

        efi_guid_to_str(&var->VendorGuid, str);
        str += strlen(str);
        str += sprintf(str, "\n");

        return str - buf;
}

static ssize_t
efivar_attr_read(struct efivar_entry *entry, char *buf)
{
        struct efi_variable *var = &entry->var;
        char *str = buf;

        if (!entry || !buf)
                return -EINVAL;

        var->DataSize = 1024;
        if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
                return -EIO;

        if (var->Attributes & EFI_VARIABLE_NON_VOLATILE)
                str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
        if (var->Attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)
                str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
        if (var->Attributes & EFI_VARIABLE_RUNTIME_ACCESS)
                str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
        if (var->Attributes & EFI_VARIABLE_HARDWARE_ERROR_RECORD)
                str += sprintf(str, "EFI_VARIABLE_HARDWARE_ERROR_RECORD\n");
        if (var->Attributes & EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS)
                str += sprintf(str,
                        "EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS\n");
        if (var->Attributes &
                        EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)
                str += sprintf(str,
                        "EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS\n");
        if (var->Attributes & EFI_VARIABLE_APPEND_WRITE)
                str += sprintf(str, "EFI_VARIABLE_APPEND_WRITE\n");
        return str - buf;
}

static ssize_t
efivar_size_read(struct efivar_entry *entry, char *buf)
{
        struct efi_variable *var = &entry->var;
        char *str = buf;

        if (!entry || !buf)
                return -EINVAL;

        var->DataSize = 1024;
        if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
                return -EIO;

        str += sprintf(str, "0x%lx\n", var->DataSize);
        return str - buf;
}

static ssize_t
efivar_data_read(struct efivar_entry *entry, char *buf)
{
        struct efi_variable *var = &entry->var;

        if (!entry || !buf)
                return -EINVAL;

        var->DataSize = 1024;
        if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
                return -EIO;

        memcpy(buf, var->Data, var->DataSize);
        return var->DataSize;
}

static inline int
sanity_check(struct efi_variable *var, efi_char16_t *name, efi_guid_t vendor,
             unsigned long size, u32 attributes, u8 *data)
{
        /*
         * If only updating the variable data, then the name
         * and guid should remain the same
         */
        if (memcmp(name, var->VariableName, sizeof(var->VariableName)) ||
                efi_guidcmp(vendor, var->VendorGuid)) {
                printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
                return -EINVAL;
        }

        if ((size <= 0) || (attributes == 0)){
                printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
                return -EINVAL;
        }

        if ((attributes & ~EFI_VARIABLE_MASK) != 0 ||
            efivar_validate(vendor, name, data, size) == false) {
                printk(KERN_ERR "efivars: Malformed variable content\n");
                return -EINVAL;
        }

        return 0;
}

static inline bool is_compat(void)
{
        if (IS_ENABLED(CONFIG_COMPAT) && in_compat_syscall())
                return true;

        return false;
}

static void
copy_out_compat(struct efi_variable *dst, struct compat_efi_variable *src)
{
        memcpy(dst->VariableName, src->VariableName, EFI_VAR_NAME_LEN);
        memcpy(dst->Data, src->Data, sizeof(src->Data));

        dst->VendorGuid = src->VendorGuid;
        dst->DataSize = src->DataSize;
        dst->Attributes = src->Attributes;
}

/*
 * We allow each variable to be edited via rewriting the
 * entire efi variable structure.
 */
static ssize_t
efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
{
        struct efi_variable *new_var, *var = &entry->var;
        efi_char16_t *name;
        unsigned long size;
        efi_guid_t vendor;
        u32 attributes;
        u8 *data;
        int err;

        if (is_compat()) {
                struct compat_efi_variable *compat;

                if (count != sizeof(*compat))
                        return -EINVAL;

                compat = (struct compat_efi_variable *)buf;
                attributes = compat->Attributes;
                vendor = compat->VendorGuid;
                name = compat->VariableName;
                size = compat->DataSize;
                data = compat->Data;

                err = sanity_check(var, name, vendor, size, attributes, data);
                if (err)
                        return err;

                copy_out_compat(&entry->var, compat);
        } else {
                if (count != sizeof(struct efi_variable))
                        return -EINVAL;

                new_var = (struct efi_variable *)buf;

                attributes = new_var->Attributes;
                vendor = new_var->VendorGuid;
                name = new_var->VariableName;
                size = new_var->DataSize;
                data = new_var->Data;

                err = sanity_check(var, name, vendor, size, attributes, data);
                if (err)
                        return err;

                memcpy(&entry->var, new_var, count);
        }

        err = efivar_entry_set(entry, attributes, size, data, NULL);
        if (err) {
                printk(KERN_WARNING "efivars: set_variable() failed: status=%d\n", err);
                return -EIO;
        }

        return count;
}

static ssize_t
efivar_show_raw(struct efivar_entry *entry, char *buf)
{
        struct efi_variable *var = &entry->var;
        struct compat_efi_variable *compat;
        size_t size;

        if (!entry || !buf)
                return 0;

        var->DataSize = 1024;
        if (efivar_entry_get(entry, &entry->var.Attributes,
                             &entry->var.DataSize, entry->var.Data))
                return -EIO;

        if (is_compat()) {
                compat = (struct compat_efi_variable *)buf;

                size = sizeof(*compat);
                memcpy(compat->VariableName, var->VariableName,
                        EFI_VAR_NAME_LEN);
                memcpy(compat->Data, var->Data, sizeof(compat->Data));

                compat->VendorGuid = var->VendorGuid;
                compat->DataSize = var->DataSize;
                compat->Attributes = var->Attributes;
        } else {
                size = sizeof(*var);
                memcpy(buf, var, size);
        }

        return size;
}

/*
 * Generic read/write functions that call the specific functions of
 * the attributes...
 */
static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
                                char *buf)
{
        struct efivar_entry *var = to_efivar_entry(kobj);
        struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
        ssize_t ret = -EIO;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        if (efivar_attr->show) {
                ret = efivar_attr->show(var, buf);
        }
        return ret;
}

static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
                                const char *buf, size_t count)
{
        struct efivar_entry *var = to_efivar_entry(kobj);
        struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
        ssize_t ret = -EIO;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        if (efivar_attr->store)
                ret = efivar_attr->store(var, buf, count);

        return ret;
}

static const struct sysfs_ops efivar_attr_ops = {
        .show = efivar_attr_show,
        .store = efivar_attr_store,
};

static void efivar_release(struct kobject *kobj)
{
        struct efivar_entry *var = to_efivar_entry(kobj);
        kfree(var);
}

static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);

static struct attribute *def_attrs[] = {
        &efivar_attr_guid.attr,
        &efivar_attr_size.attr,
        &efivar_attr_attributes.attr,
        &efivar_attr_data.attr,
        &efivar_attr_raw_var.attr,
        NULL,
};

static struct kobj_type efivar_ktype = {
        .release = efivar_release,
        .sysfs_ops = &efivar_attr_ops,
        .default_attrs = def_attrs,
};

static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
                             struct bin_attribute *bin_attr,
                             char *buf, loff_t pos, size_t count)
{
        struct compat_efi_variable *compat = (struct compat_efi_variable *)buf;
        struct efi_variable *new_var = (struct efi_variable *)buf;
        struct efivar_entry *new_entry;
        bool need_compat = is_compat();
        efi_char16_t *name;
        unsigned long size;
        u32 attributes;
        u8 *data;
        int err;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        if (need_compat) {
                if (count != sizeof(*compat))
                        return -EINVAL;

                attributes = compat->Attributes;
                name = compat->VariableName;
                size = compat->DataSize;
                data = compat->Data;
        } else {
                if (count != sizeof(*new_var))
                        return -EINVAL;

                attributes = new_var->Attributes;
                name = new_var->VariableName;
                size = new_var->DataSize;
                data = new_var->Data;
        }

        if ((attributes & ~EFI_VARIABLE_MASK) != 0 ||
            efivar_validate(new_var->VendorGuid, name, data,
                            size) == false) {
                printk(KERN_ERR "efivars: Malformed variable content\n");
                return -EINVAL;
        }

        new_entry = kzalloc(sizeof(*new_entry), GFP_KERNEL);
        if (!new_entry)
                return -ENOMEM;

        if (need_compat)
                copy_out_compat(&new_entry->var, compat);
        else
                memcpy(&new_entry->var, new_var, sizeof(*new_var));

        err = efivar_entry_set(new_entry, attributes, size,
                               data, &efivar_sysfs_list);
        if (err) {
                if (err == -EEXIST)
                        err = -EINVAL;
                goto out;
        }

        if (efivar_create_sysfs_entry(new_entry)) {
                printk(KERN_WARNING "efivars: failed to create sysfs entry.\n");
                kfree(new_entry);
        }
        return count;

out:
        kfree(new_entry);
        return err;
}

static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
                             struct bin_attribute *bin_attr,
                             char *buf, loff_t pos, size_t count)
{
        struct efi_variable *del_var = (struct efi_variable *)buf;
        struct compat_efi_variable *compat;
        struct efivar_entry *entry;
        efi_char16_t *name;
        efi_guid_t vendor;
        int err = 0;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;

        if (is_compat()) {
                if (count != sizeof(*compat))
                        return -EINVAL;

                compat = (struct compat_efi_variable *)buf;
                name = compat->VariableName;
                vendor = compat->VendorGuid;
        } else {
                if (count != sizeof(*del_var))
                        return -EINVAL;

                name = del_var->VariableName;
                vendor = del_var->VendorGuid;
        }

        if (efivar_entry_iter_begin())
                return -EINTR;
        entry = efivar_entry_find(name, vendor, &efivar_sysfs_list, true);
        if (!entry)
                err = -EINVAL;
        else if (__efivar_entry_delete(entry))
                err = -EIO;

        if (err) {
                efivar_entry_iter_end();
                return err;
        }

        if (!entry->scanning) {
                efivar_entry_iter_end();
                efivar_unregister(entry);
        } else
                efivar_entry_iter_end();

        /* It's dead Jim.... */
        return count;
}

/**
 * efivar_create_sysfs_entry - create a new entry in sysfs
 * @new_var: efivar entry to create
 *
 * Returns 0 on success, negative error code on failure
 */
static int
efivar_create_sysfs_entry(struct efivar_entry *new_var)
{
        int short_name_size;
        char *short_name;
        unsigned long utf8_name_size;
        efi_char16_t *variable_name = new_var->var.VariableName;
        int ret;

        /*
         * Length of the variable bytes in UTF8, plus the '-' separator,
         * plus the GUID, plus trailing NUL
         */
        utf8_name_size = ucs2_utf8size(variable_name);
        short_name_size = utf8_name_size + 1 + EFI_VARIABLE_GUID_LEN + 1;

        short_name = kmalloc(short_name_size, GFP_KERNEL);
        if (!short_name)
                return -ENOMEM;

        ucs2_as_utf8(short_name, variable_name, short_name_size);

        /* This is ugly, but necessary to separate one vendor's
           private variables from another's.         */
        short_name[utf8_name_size] = '-';
        efi_guid_to_str(&new_var->var.VendorGuid,
                         short_name + utf8_name_size + 1);

        new_var->kobj.kset = efivars_kset;

        ret = kobject_init_and_add(&new_var->kobj, &efivar_ktype,
                                   NULL, "%s", short_name);
        kfree(short_name);
        if (ret)
                return ret;

        kobject_uevent(&new_var->kobj, KOBJ_ADD);
        if (efivar_entry_add(new_var, &efivar_sysfs_list)) {
                efivar_unregister(new_var);
                return -EINTR;
        }

        return 0;
}

static int
create_efivars_bin_attributes(void)
{
        struct bin_attribute *attr;
        int error;

        /* new_var */
        attr = kzalloc(sizeof(*attr), GFP_KERNEL);
        if (!attr)
                return -ENOMEM;

        attr->attr.name = "new_var";
        attr->attr.mode = 0200;
        attr->write = efivar_create;
        efivars_new_var = attr;

        /* del_var */
        attr = kzalloc(sizeof(*attr), GFP_KERNEL);
        if (!attr) {
                error = -ENOMEM;
                goto out_free;
        }
        attr->attr.name = "del_var";
        attr->attr.mode = 0200;
        attr->write = efivar_delete;
        efivars_del_var = attr;

        sysfs_bin_attr_init(efivars_new_var);
        sysfs_bin_attr_init(efivars_del_var);

        /* Register */
        error = sysfs_create_bin_file(&efivars_kset->kobj, efivars_new_var);
        if (error) {
                printk(KERN_ERR "efivars: unable to create new_var sysfs file"
                        " due to error %d\n", error);
                goto out_free;
        }

        error = sysfs_create_bin_file(&efivars_kset->kobj, efivars_del_var);
        if (error) {
                printk(KERN_ERR "efivars: unable to create del_var sysfs file"
                        " due to error %d\n", error);
                sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var);
                goto out_free;
        }

        return 0;
out_free:
        kfree(efivars_del_var);
        efivars_del_var = NULL;
        kfree(efivars_new_var);
        efivars_new_var = NULL;
        return error;
}

static int efivar_update_sysfs_entry(efi_char16_t *name, efi_guid_t vendor,
                                     unsigned long name_size, void *data)
{
        struct efivar_entry *entry = data;

        if (efivar_entry_find(name, vendor, &efivar_sysfs_list, false))
                return 0;

        memcpy(entry->var.VariableName, name, name_size);
        memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));

        return 1;
}

static void efivar_update_sysfs_entries(struct work_struct *work)
{
        struct efivar_entry *entry;
        int err;

        /* Add new sysfs entries */
        while (1) {
                entry = kzalloc(sizeof(*entry), GFP_KERNEL);
                if (!entry)
                        return;

                err = efivar_init(efivar_update_sysfs_entry, entry,
                                  false, &efivar_sysfs_list);
                if (!err)
                        break;

                efivar_create_sysfs_entry(entry);
        }

        kfree(entry);
}

static int efivars_sysfs_callback(efi_char16_t *name, efi_guid_t vendor,
                                  unsigned long name_size, void *data)
{
        struct efivar_entry *entry;

        entry = kzalloc(sizeof(*entry), GFP_KERNEL);
        if (!entry)
                return -ENOMEM;

        memcpy(entry->var.VariableName, name, name_size);
        memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));

        efivar_create_sysfs_entry(entry);

        return 0;
}

static int efivar_sysfs_destroy(struct efivar_entry *entry, void *data)
{
        int err = efivar_entry_remove(entry);

        if (err)
                return err;
        efivar_unregister(entry);
        return 0;
}

static void efivars_sysfs_exit(void)
{
        /* Remove all entries and destroy */
        int err;

        err = __efivar_entry_iter(efivar_sysfs_destroy, &efivar_sysfs_list,
                                  NULL, NULL);
        if (err) {
                pr_err("efivars: Failed to destroy sysfs entries\n");
                return;
        }

        if (efivars_new_var)
                sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var);
        if (efivars_del_var)
                sysfs_remove_bin_file(&efivars_kset->kobj, efivars_del_var);
        kfree(efivars_new_var);
        kfree(efivars_del_var);
        kset_unregister(efivars_kset);
}

int efivars_sysfs_init(void)
{
        struct kobject *parent_kobj = efivars_kobject();
        int error = 0;

        if (!efi_enabled(EFI_RUNTIME_SERVICES))
                return -ENODEV;

        /* No efivars has been registered yet */
        if (!parent_kobj)
                return 0;

        printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
               EFIVARS_DATE);

        efivars_kset = kset_create_and_add("vars", NULL, parent_kobj);
        if (!efivars_kset) {
                printk(KERN_ERR "efivars: Subsystem registration failed.\n");
                return -ENOMEM;
        }

        efivar_init(efivars_sysfs_callback, NULL, true, &efivar_sysfs_list);

        error = create_efivars_bin_attributes();
        if (error) {
                efivars_sysfs_exit();
                return error;
        }

        INIT_WORK(&efivar_work, efivar_update_sysfs_entries);

        return 0;
}
EXPORT_SYMBOL_GPL(efivars_sysfs_init);

module_init(efivars_sysfs_init);
module_exit(efivars_sysfs_exit);