// SPDX-License-Identifier: GPL-2.0+
/*
 * EFI Test Driver for Runtime Services
 *
 * Copyright(C) 2012-2016 Canonical Ltd.
 *
 * This driver exports EFI runtime services interfaces into userspace, which
 * allow to use and test UEFI runtime services provided by firmware.
 *
 */

#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/efi.h>
#include <linux/security.h>
#include <linux/slab.h>
#include <linux/uaccess.h>

#include "efi_test.h"

MODULE_AUTHOR("Ivan Hu <ivan.hu@canonical.com>");
MODULE_DESCRIPTION("EFI Test Driver");
MODULE_LICENSE("GPL");

/*
 * Count the bytes in 'str', including the terminating NULL.
 *
 * Note this function returns the number of *bytes*, not the number of
 * ucs2 characters.
 */
static inline size_t user_ucs2_strsize(efi_char16_t  __user *str)
{
        efi_char16_t *s = str, c;
        size_t len;

        if (!str)
                return 0;

        /* Include terminating NULL */
        len = sizeof(efi_char16_t);

        if (get_user(c, s++)) {
                /* Can't read userspace memory for size */
                return 0;
        }

        while (c != 0) {
                if (get_user(c, s++)) {
                        /* Can't read userspace memory for size */
                        return 0;
                }
                len += sizeof(efi_char16_t);
        }
        return len;
}

/*
 * Allocate a buffer and copy a ucs2 string from user space into it.
 */
static inline int
copy_ucs2_from_user_len(efi_char16_t **dst, efi_char16_t __user *src,
                        size_t len)
{
        efi_char16_t *buf;

        if (!src) {
                *dst = NULL;
                return 0;
        }

        buf = memdup_user(src, len);
        if (IS_ERR(buf)) {
                *dst = NULL;
                return PTR_ERR(buf);
        }
        *dst = buf;

        return 0;
}

/*
 * Count the bytes in 'str', including the terminating NULL.
 *
 * Just a wrap for user_ucs2_strsize
 */
static inline int
get_ucs2_strsize_from_user(efi_char16_t __user *src, size_t *len)
{
        *len = user_ucs2_strsize(src);
        if (*len == 0)
                return -EFAULT;

        return 0;
}

/*
 * Calculate the required buffer allocation size and copy a ucs2 string
 * from user space into it.
 *
 * This function differs from copy_ucs2_from_user_len() because it
 * calculates the size of the buffer to allocate by taking the length of
 * the string 'src'.
 *
 * If a non-zero value is returned, the caller MUST NOT access 'dst'.
 *
 * It is the caller's responsibility to free 'dst'.
 */
static inline int
copy_ucs2_from_user(efi_char16_t **dst, efi_char16_t __user *src)
{
        size_t len;

        len = user_ucs2_strsize(src);
        if (len == 0)
                return -EFAULT;
        return copy_ucs2_from_user_len(dst, src, len);
}

/*
 * Copy a ucs2 string to a user buffer.
 *
 * This function is a simple wrapper around copy_to_user() that does
 * nothing if 'src' is NULL, which is useful for reducing the amount of
 * NULL checking the caller has to do.
 *
 * 'len' specifies the number of bytes to copy.
 */
static inline int
copy_ucs2_to_user_len(efi_char16_t __user *dst, efi_char16_t *src, size_t len)
{
        if (!src)
                return 0;

        return copy_to_user(dst, src, len);
}

static long efi_runtime_get_variable(unsigned long arg)
{
        struct efi_getvariable __user *getvariable_user;
        struct efi_getvariable getvariable;
        unsigned long datasize = 0, prev_datasize, *dz;
        efi_guid_t vendor_guid, *vd = NULL;
        efi_status_t status;
        efi_char16_t *name = NULL;
        u32 attr, *at;
        void *data = NULL;
        int rv = 0;

        getvariable_user = (struct efi_getvariable __user *)arg;

        if (copy_from_user(&getvariable, getvariable_user,
                           sizeof(getvariable)))
                return -EFAULT;
        if (getvariable.data_size &&
            get_user(datasize, getvariable.data_size))
                return -EFAULT;
        if (getvariable.vendor_guid) {
                if (copy_from_user(&vendor_guid, getvariable.vendor_guid,
                                        sizeof(vendor_guid)))
                        return -EFAULT;
                vd = &vendor_guid;
        }

        if (getvariable.variable_name) {
                rv = copy_ucs2_from_user(&name, getvariable.variable_name);
                if (rv)
                        return rv;
        }

        at = getvariable.attributes ? &attr : NULL;
        dz = getvariable.data_size ? &datasize : NULL;

        if (getvariable.data_size && getvariable.data) {
                data = kmalloc(datasize, GFP_KERNEL);
                if (!data) {
                        kfree(name);
                        return -ENOMEM;
                }
        }

        prev_datasize = datasize;
        status = efi.get_variable(name, vd, at, dz, data);
        kfree(name);

        if (put_user(status, getvariable.status)) {
                rv = -EFAULT;
                goto out;
        }

        if (status != EFI_SUCCESS) {
                if (status == EFI_BUFFER_TOO_SMALL) {
                        if (dz && put_user(datasize, getvariable.data_size)) {
                                rv = -EFAULT;
                                goto out;
                        }
                }
                rv = -EINVAL;
                goto out;
        }

        if (prev_datasize < datasize) {
                rv = -EINVAL;
                goto out;
        }

        if (data) {
                if (copy_to_user(getvariable.data, data, datasize)) {
                        rv = -EFAULT;
                        goto out;
                }
        }

        if (at && put_user(attr, getvariable.attributes)) {
                rv = -EFAULT;
                goto out;
        }

        if (dz && put_user(datasize, getvariable.data_size))
                rv = -EFAULT;

out:
        kfree(data);
        return rv;

}

static long efi_runtime_set_variable(unsigned long arg)
{
        struct efi_setvariable __user *setvariable_user;
        struct efi_setvariable setvariable;
        efi_guid_t vendor_guid;
        efi_status_t status;
        efi_char16_t *name = NULL;
        void *data;
        int rv = 0;

        setvariable_user = (struct efi_setvariable __user *)arg;

        if (copy_from_user(&setvariable, setvariable_user, sizeof(setvariable)))
                return -EFAULT;
        if (copy_from_user(&vendor_guid, setvariable.vendor_guid,
                                sizeof(vendor_guid)))
                return -EFAULT;

        if (setvariable.variable_name) {
                rv = copy_ucs2_from_user(&name, setvariable.variable_name);
                if (rv)
                        return rv;
        }

        data = memdup_user(setvariable.data, setvariable.data_size);
        if (IS_ERR(data)) {
                kfree(name);
                return PTR_ERR(data);
        }

        status = efi.set_variable(name, &vendor_guid,
                                setvariable.attributes,
                                setvariable.data_size, data);

        if (put_user(status, setvariable.status)) {
                rv = -EFAULT;
                goto out;
        }

        rv = status == EFI_SUCCESS ? 0 : -EINVAL;

out:
        kfree(data);
        kfree(name);

        return rv;
}

static long efi_runtime_get_time(unsigned long arg)
{
        struct efi_gettime __user *gettime_user;
        struct efi_gettime  gettime;
        efi_status_t status;
        efi_time_cap_t cap;
        efi_time_t efi_time;

        gettime_user = (struct efi_gettime __user *)arg;
        if (copy_from_user(&gettime, gettime_user, sizeof(gettime)))
                return -EFAULT;

        status = efi.get_time(gettime.time ? &efi_time : NULL,
                              gettime.capabilities ? &cap : NULL);

        if (put_user(status, gettime.status))
                return -EFAULT;

        if (status != EFI_SUCCESS)
                return -EINVAL;

        if (gettime.capabilities) {
                efi_time_cap_t __user *cap_local;

                cap_local = (efi_time_cap_t *)gettime.capabilities;
                if (put_user(cap.resolution, &(cap_local->resolution)) ||
                        put_user(cap.accuracy, &(cap_local->accuracy)) ||
                        put_user(cap.sets_to_zero, &(cap_local->sets_to_zero)))
                        return -EFAULT;
        }
        if (gettime.time) {
                if (copy_to_user(gettime.time, &efi_time, sizeof(efi_time_t)))
                        return -EFAULT;
        }

        return 0;
}

static long efi_runtime_set_time(unsigned long arg)
{
        struct efi_settime __user *settime_user;
        struct efi_settime settime;
        efi_status_t status;
        efi_time_t efi_time;

        settime_user = (struct efi_settime __user *)arg;
        if (copy_from_user(&settime, settime_user, sizeof(settime)))
                return -EFAULT;
        if (copy_from_user(&efi_time, settime.time,
                                        sizeof(efi_time_t)))
                return -EFAULT;
        status = efi.set_time(&efi_time);

        if (put_user(status, settime.status))
                return -EFAULT;

        return status == EFI_SUCCESS ? 0 : -EINVAL;
}

static long efi_runtime_get_waketime(unsigned long arg)
{
        struct efi_getwakeuptime __user *getwakeuptime_user;
        struct efi_getwakeuptime getwakeuptime;
        efi_bool_t enabled, pending;
        efi_status_t status;
        efi_time_t efi_time;

        getwakeuptime_user = (struct efi_getwakeuptime __user *)arg;
        if (copy_from_user(&getwakeuptime, getwakeuptime_user,
                                sizeof(getwakeuptime)))
                return -EFAULT;

        status = efi.get_wakeup_time(
                getwakeuptime.enabled ? (efi_bool_t *)&enabled : NULL,
                getwakeuptime.pending ? (efi_bool_t *)&pending : NULL,
                getwakeuptime.time ? &efi_time : NULL);

        if (put_user(status, getwakeuptime.status))
                return -EFAULT;

        if (status != EFI_SUCCESS)
                return -EINVAL;

        if (getwakeuptime.enabled && put_user(enabled,
                                                getwakeuptime.enabled))
                return -EFAULT;

        if (getwakeuptime.pending && put_user(pending,
                                                getwakeuptime.pending))
                return -EFAULT;

        if (getwakeuptime.time) {
                if (copy_to_user(getwakeuptime.time, &efi_time,
                                sizeof(efi_time_t)))
                        return -EFAULT;
        }

        return 0;
}

static long efi_runtime_set_waketime(unsigned long arg)
{
        struct efi_setwakeuptime __user *setwakeuptime_user;
        struct efi_setwakeuptime setwakeuptime;
        efi_bool_t enabled;
        efi_status_t status;
        efi_time_t efi_time;

        setwakeuptime_user = (struct efi_setwakeuptime __user *)arg;

        if (copy_from_user(&setwakeuptime, setwakeuptime_user,
                                sizeof(setwakeuptime)))
                return -EFAULT;

        enabled = setwakeuptime.enabled;
        if (setwakeuptime.time) {
                if (copy_from_user(&efi_time, setwakeuptime.time,
                                        sizeof(efi_time_t)))
                        return -EFAULT;

                status = efi.set_wakeup_time(enabled, &efi_time);
        } else
                status = efi.set_wakeup_time(enabled, NULL);

        if (put_user(status, setwakeuptime.status))
                return -EFAULT;

        return status == EFI_SUCCESS ? 0 : -EINVAL;
}

static long efi_runtime_get_nextvariablename(unsigned long arg)
{
        struct efi_getnextvariablename __user *getnextvariablename_user;
        struct efi_getnextvariablename getnextvariablename;
        unsigned long name_size, prev_name_size = 0, *ns = NULL;
        efi_status_t status;
        efi_guid_t *vd = NULL;
        efi_guid_t vendor_guid;
        efi_char16_t *name = NULL;
        int rv = 0;

        getnextvariablename_user = (struct efi_getnextvariablename __user *)arg;

        if (copy_from_user(&getnextvariablename, getnextvariablename_user,
                           sizeof(getnextvariablename)))
                return -EFAULT;

        if (getnextvariablename.variable_name_size) {
                if (get_user(name_size, getnextvariablename.variable_name_size))
                        return -EFAULT;
                ns = &name_size;
                prev_name_size = name_size;
        }

        if (getnextvariablename.vendor_guid) {
                if (copy_from_user(&vendor_guid,
                                getnextvariablename.vendor_guid,
                                sizeof(vendor_guid)))
                        return -EFAULT;
                vd = &vendor_guid;
        }

        if (getnextvariablename.variable_name) {
                size_t name_string_size = 0;

                rv = get_ucs2_strsize_from_user(
                                getnextvariablename.variable_name,
                                &name_string_size);
                if (rv)
                        return rv;
                /*
                 * The name_size may be smaller than the real buffer size where
                 * variable name located in some use cases. The most typical
                 * case is passing a 0 to get the required buffer size for the
                 * 1st time call. So we need to copy the content from user
                 * space for at least the string size of variable name, or else
                 * the name passed to UEFI may not be terminated as we expected.
                 */
                rv = copy_ucs2_from_user_len(&name,
                                getnextvariablename.variable_name,
                                prev_name_size > name_string_size ?
                                prev_name_size : name_string_size);
                if (rv)
                        return rv;
        }

        status = efi.get_next_variable(ns, name, vd);

        if (put_user(status, getnextvariablename.status)) {
                rv = -EFAULT;
                goto out;
        }

        if (status != EFI_SUCCESS) {
                if (status == EFI_BUFFER_TOO_SMALL) {
                        if (ns && put_user(*ns,
                                getnextvariablename.variable_name_size)) {
                                rv = -EFAULT;
                                goto out;
                        }
                }
                rv = -EINVAL;
                goto out;
        }

        if (name) {
                if (copy_ucs2_to_user_len(getnextvariablename.variable_name,
                                                name, prev_name_size)) {
                        rv = -EFAULT;
                        goto out;
                }
        }

        if (ns) {
                if (put_user(*ns, getnextvariablename.variable_name_size)) {
                        rv = -EFAULT;
                        goto out;
                }
        }

        if (vd) {
                if (copy_to_user(getnextvariablename.vendor_guid, vd,
                                                        sizeof(efi_guid_t)))
                        rv = -EFAULT;
        }

out:
        kfree(name);
        return rv;
}

static long efi_runtime_get_nexthighmonocount(unsigned long arg)
{
        struct efi_getnexthighmonotoniccount __user *getnexthighmonocount_user;
        struct efi_getnexthighmonotoniccount getnexthighmonocount;
        efi_status_t status;
        u32 count;

        getnexthighmonocount_user = (struct
                        efi_getnexthighmonotoniccount __user *)arg;

        if (copy_from_user(&getnexthighmonocount,
                           getnexthighmonocount_user,
                           sizeof(getnexthighmonocount)))
                return -EFAULT;

        status = efi.get_next_high_mono_count(
                getnexthighmonocount.high_count ? &count : NULL);

        if (put_user(status, getnexthighmonocount.status))
                return -EFAULT;

        if (status != EFI_SUCCESS)
                return -EINVAL;

        if (getnexthighmonocount.high_count &&
            put_user(count, getnexthighmonocount.high_count))
                return -EFAULT;

        return 0;
}

static long efi_runtime_reset_system(unsigned long arg)
{
        struct efi_resetsystem __user *resetsystem_user;
        struct efi_resetsystem resetsystem;
        void *data = NULL;

        resetsystem_user = (struct efi_resetsystem __user *)arg;
        if (copy_from_user(&resetsystem, resetsystem_user,
                                                sizeof(resetsystem)))
                return -EFAULT;
        if (resetsystem.data_size != 0) {
                data = memdup_user((void *)resetsystem.data,
                                                resetsystem.data_size);
                if (IS_ERR(data))
                        return PTR_ERR(data);
        }

        efi.reset_system(resetsystem.reset_type, resetsystem.status,
                                resetsystem.data_size, (efi_char16_t *)data);

        kfree(data);
        return 0;
}

static long efi_runtime_query_variableinfo(unsigned long arg)
{
        struct efi_queryvariableinfo __user *queryvariableinfo_user;
        struct efi_queryvariableinfo queryvariableinfo;
        efi_status_t status;
        u64 max_storage, remaining, max_size;

        queryvariableinfo_user = (struct efi_queryvariableinfo __user *)arg;

        if (copy_from_user(&queryvariableinfo, queryvariableinfo_user,
                           sizeof(queryvariableinfo)))
                return -EFAULT;

        status = efi.query_variable_info(queryvariableinfo.attributes,
                                         &max_storage, &remaining, &max_size);

        if (put_user(status, queryvariableinfo.status))
                return -EFAULT;

        if (status != EFI_SUCCESS)
                return -EINVAL;

        if (put_user(max_storage,
                     queryvariableinfo.maximum_variable_storage_size))
                return -EFAULT;

        if (put_user(remaining,
                     queryvariableinfo.remaining_variable_storage_size))
                return -EFAULT;

        if (put_user(max_size, queryvariableinfo.maximum_variable_size))
                return -EFAULT;

        return 0;
}

static long efi_runtime_query_capsulecaps(unsigned long arg)
{
        struct efi_querycapsulecapabilities __user *qcaps_user;
        struct efi_querycapsulecapabilities qcaps;
        efi_capsule_header_t *capsules;
        efi_status_t status;
        u64 max_size;
        int i, reset_type;
        int rv = 0;

        qcaps_user = (struct efi_querycapsulecapabilities __user *)arg;

        if (copy_from_user(&qcaps, qcaps_user, sizeof(qcaps)))
                return -EFAULT;

        if (qcaps.capsule_count == ULONG_MAX)
                return -EINVAL;

        capsules = kzalloc_objs(efi_capsule_header_t, qcaps.capsule_count + 1);
        if (!capsules)
                return -ENOMEM;

        for (i = 0; i < qcaps.capsule_count; i++) {
                efi_capsule_header_t *c;
                /*
                 * We cannot dereference qcaps.capsule_header_array directly to
                 * obtain the address of the capsule as it resides in the
                 * user space
                 */
                if (get_user(c, qcaps.capsule_header_array + i)) {
                        rv = -EFAULT;
                        goto out;
                }
                if (copy_from_user(&capsules[i], c,
                                sizeof(efi_capsule_header_t))) {
                        rv = -EFAULT;
                        goto out;
                }
        }

        qcaps.capsule_header_array = &capsules;

        status = efi.query_capsule_caps((efi_capsule_header_t **)
                                        qcaps.capsule_header_array,
                                        qcaps.capsule_count,
                                        &max_size, &reset_type);

        if (put_user(status, qcaps.status)) {
                rv = -EFAULT;
                goto out;
        }

        if (status != EFI_SUCCESS) {
                rv = -EINVAL;
                goto out;
        }

        if (put_user(max_size, qcaps.maximum_capsule_size)) {
                rv = -EFAULT;
                goto out;
        }

        if (put_user(reset_type, qcaps.reset_type))
                rv = -EFAULT;

out:
        kfree(capsules);
        return rv;
}

static long efi_runtime_get_supported_mask(unsigned long arg)
{
        unsigned int __user *supported_mask;
        int rv = 0;

        supported_mask = (unsigned int *)arg;

        if (put_user(efi.runtime_supported_mask, supported_mask))
                rv = -EFAULT;

        return rv;
}

static long efi_test_ioctl(struct file *file, unsigned int cmd,
                                                        unsigned long arg)
{
        switch (cmd) {
        case EFI_RUNTIME_GET_VARIABLE:
                return efi_runtime_get_variable(arg);

        case EFI_RUNTIME_SET_VARIABLE:
                return efi_runtime_set_variable(arg);

        case EFI_RUNTIME_GET_TIME:
                return efi_runtime_get_time(arg);

        case EFI_RUNTIME_SET_TIME:
                return efi_runtime_set_time(arg);

        case EFI_RUNTIME_GET_WAKETIME:
                return efi_runtime_get_waketime(arg);

        case EFI_RUNTIME_SET_WAKETIME:
                return efi_runtime_set_waketime(arg);

        case EFI_RUNTIME_GET_NEXTVARIABLENAME:
                return efi_runtime_get_nextvariablename(arg);

        case EFI_RUNTIME_GET_NEXTHIGHMONOTONICCOUNT:
                return efi_runtime_get_nexthighmonocount(arg);

        case EFI_RUNTIME_QUERY_VARIABLEINFO:
                return efi_runtime_query_variableinfo(arg);

        case EFI_RUNTIME_QUERY_CAPSULECAPABILITIES:
                return efi_runtime_query_capsulecaps(arg);

        case EFI_RUNTIME_RESET_SYSTEM:
                return efi_runtime_reset_system(arg);

        case EFI_RUNTIME_GET_SUPPORTED_MASK:
                return efi_runtime_get_supported_mask(arg);
        }

        return -ENOTTY;
}

static int efi_test_open(struct inode *inode, struct file *file)
{
        int ret = security_locked_down(LOCKDOWN_EFI_TEST);

        if (ret)
                return ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;
        /*
         * nothing special to do here
         * We do accept multiple open files at the same time as we
         * synchronize on the per call operation.
         */
        return 0;
}

static int efi_test_close(struct inode *inode, struct file *file)
{
        return 0;
}

/*
 *      The various file operations we support.
 */
static const struct file_operations efi_test_fops = {
        .owner          = THIS_MODULE,
        .unlocked_ioctl = efi_test_ioctl,
        .open           = efi_test_open,
        .release        = efi_test_close,
};

static struct miscdevice efi_test_dev = {
        MISC_DYNAMIC_MINOR,
        "efi_test",
        &efi_test_fops
};

static int __init efi_test_init(void)
{
        int ret;

        ret = misc_register(&efi_test_dev);
        if (ret) {
                pr_err("efi_test: can't misc_register on minor=%d\n",
                        MISC_DYNAMIC_MINOR);
                return ret;
        }

        return 0;
}

static void __exit efi_test_exit(void)
{
        misc_deregister(&efi_test_dev);
}

module_init(efi_test_init);
module_exit(efi_test_exit);