![Mario Limonciello](/assets/img/avatar_default.png)
This application uses the character device /dev/wmi/dell-smbios to perform SMBIOS communications from userspace. It offers demonstrations of a few simple tasks: - Running a class/select command - Querying a token value - Activating a token Signed-off-by: Mario Limonciello <mario.limonciello@dell.com> Reviewed-by: Edward O'Callaghan <quasisec@google.com> Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>
211 lines
4.9 KiB
C
211 lines
4.9 KiB
C
/*
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* Sample application for SMBIOS communication over WMI interface
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* Performs the following:
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* - Simple cmd_class/cmd_select lookup for TPM information
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* - Simple query of known tokens and their values
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* - Simple activation of a token
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*
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* Copyright (C) 2017 Dell, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/ioctl.h>
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#include <unistd.h>
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/* if uapi header isn't installed, this might not yet exist */
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#ifndef __packed
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#define __packed __attribute__((packed))
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#endif
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#include <linux/wmi.h>
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/* It would be better to discover these using udev, but for a simple
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* application they're hardcoded
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*/
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static const char *ioctl_devfs = "/dev/wmi/dell-smbios";
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static const char *token_sysfs =
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"/sys/bus/platform/devices/dell-smbios.0/tokens";
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static void show_buffer(struct dell_wmi_smbios_buffer *buffer)
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{
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printf("Call: %x/%x [%x,%x,%x,%x]\nResults: [%8x,%8x,%8x,%8x]\n",
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buffer->std.cmd_class, buffer->std.cmd_select,
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buffer->std.input[0], buffer->std.input[1],
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buffer->std.input[2], buffer->std.input[3],
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buffer->std.output[0], buffer->std.output[1],
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buffer->std.output[2], buffer->std.output[3]);
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}
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static int run_wmi_smbios_cmd(struct dell_wmi_smbios_buffer *buffer)
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{
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int fd;
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int ret;
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fd = open(ioctl_devfs, O_NONBLOCK);
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ret = ioctl(fd, DELL_WMI_SMBIOS_CMD, buffer);
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close(fd);
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return ret;
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}
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static int find_token(__u16 token, __u16 *location, __u16 *value)
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{
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char location_sysfs[60];
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char value_sysfs[57];
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char buf[4096];
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FILE *f;
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int ret;
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ret = sprintf(value_sysfs, "%s/%04x_value", token_sysfs, token);
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if (ret < 0) {
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printf("sprintf value failed\n");
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return 2;
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}
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f = fopen(value_sysfs, "rb");
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if (!f) {
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printf("failed to open %s\n", value_sysfs);
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return 2;
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}
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fread(buf, 1, 4096, f);
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fclose(f);
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*value = (__u16) strtol(buf, NULL, 16);
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ret = sprintf(location_sysfs, "%s/%04x_location", token_sysfs, token);
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if (ret < 0) {
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printf("sprintf location failed\n");
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return 1;
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}
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f = fopen(location_sysfs, "rb");
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if (!f) {
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printf("failed to open %s\n", location_sysfs);
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return 2;
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}
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fread(buf, 1, 4096, f);
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fclose(f);
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*location = (__u16) strtol(buf, NULL, 16);
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if (*location)
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return 0;
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return 2;
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}
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static int token_is_active(__u16 *location, __u16 *cmpvalue,
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struct dell_wmi_smbios_buffer *buffer)
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{
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int ret;
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buffer->std.cmd_class = CLASS_TOKEN_READ;
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buffer->std.cmd_select = SELECT_TOKEN_STD;
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buffer->std.input[0] = *location;
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ret = run_wmi_smbios_cmd(buffer);
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if (ret != 0 || buffer->std.output[0] != 0)
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return ret;
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ret = (buffer->std.output[1] == *cmpvalue);
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return ret;
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}
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static int query_token(__u16 token, struct dell_wmi_smbios_buffer *buffer)
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{
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__u16 location;
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__u16 value;
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int ret;
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ret = find_token(token, &location, &value);
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if (ret != 0) {
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printf("unable to find token %04x\n", token);
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return 1;
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}
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return token_is_active(&location, &value, buffer);
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}
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static int activate_token(struct dell_wmi_smbios_buffer *buffer,
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__u16 token)
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{
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__u16 location;
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__u16 value;
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int ret;
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ret = find_token(token, &location, &value);
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if (ret != 0) {
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printf("unable to find token %04x\n", token);
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return 1;
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}
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buffer->std.cmd_class = CLASS_TOKEN_WRITE;
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buffer->std.cmd_select = SELECT_TOKEN_STD;
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buffer->std.input[0] = location;
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buffer->std.input[1] = 1;
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ret = run_wmi_smbios_cmd(buffer);
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return ret;
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}
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static int query_buffer_size(__u64 *buffer_size)
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{
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FILE *f;
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f = fopen(ioctl_devfs, "rb");
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if (!f)
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return -EINVAL;
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fread(buffer_size, sizeof(__u64), 1, f);
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fclose(f);
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return EXIT_SUCCESS;
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}
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int main(void)
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{
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struct dell_wmi_smbios_buffer *buffer;
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int ret;
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__u64 value = 0;
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ret = query_buffer_size(&value);
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if (ret == EXIT_FAILURE || !value) {
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printf("Unable to read buffer size\n");
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goto out;
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}
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printf("Detected required buffer size %lld\n", value);
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buffer = malloc(value);
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if (buffer == NULL) {
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printf("failed to alloc memory for ioctl\n");
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ret = -ENOMEM;
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goto out;
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}
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buffer->length = value;
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/* simple SMBIOS call for looking up TPM info */
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buffer->std.cmd_class = CLASS_FLASH_INTERFACE;
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buffer->std.cmd_select = SELECT_FLASH_INTERFACE;
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buffer->std.input[0] = 2;
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ret = run_wmi_smbios_cmd(buffer);
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if (ret) {
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printf("smbios ioctl failed: %d\n", ret);
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ret = EXIT_FAILURE;
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goto out;
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}
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show_buffer(buffer);
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/* query some tokens */
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ret = query_token(CAPSULE_EN_TOKEN, buffer);
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printf("UEFI Capsule enabled token is: %d\n", ret);
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ret = query_token(CAPSULE_DIS_TOKEN, buffer);
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printf("UEFI Capsule disabled token is: %d\n", ret);
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/* activate UEFI capsule token if disabled */
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if (ret) {
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printf("Enabling UEFI capsule token");
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if (activate_token(buffer, CAPSULE_EN_TOKEN)) {
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printf("activate failed\n");
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ret = -1;
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goto out;
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}
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}
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ret = EXIT_SUCCESS;
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out:
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free(buffer);
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return ret;
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}
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