1 /* 2 * Sample application for SMBIOS communication over WMI interface 3 * Performs the following: 4 * - Simple cmd_class/cmd_select lookup for TPM information 5 * - Simple query of known tokens and their values 6 * - Simple activation of a token 7 * 8 * Copyright (C) 2017 Dell, Inc. 9 * 10 * This program is free software; you can redistribute it and/or modify 11 * it under the terms of the GNU General Public License version 2 as 12 * published by the Free Software Foundation. 13 */ 14 15 #include <errno.h> 16 #include <fcntl.h> 17 #include <stdio.h> 18 #include <stdlib.h> 19 #include <sys/ioctl.h> 20 #include <unistd.h> 21 22 /* if uapi header isn't installed, this might not yet exist */ 23 #ifndef __packed 24 #define __packed __attribute__((packed)) 25 #endif 26 #include <linux/wmi.h> 27 28 /* It would be better to discover these using udev, but for a simple 29 * application they're hardcoded 30 */ 31 static const char *ioctl_devfs = "/dev/wmi/dell-smbios"; 32 static const char *token_sysfs = 33 "/sys/bus/platform/devices/dell-smbios.0/tokens"; 34 35 static void show_buffer(struct dell_wmi_smbios_buffer *buffer) 36 { 37 printf("Call: %x/%x [%x,%x,%x,%x]\nResults: [%8x,%8x,%8x,%8x]\n", 38 buffer->std.cmd_class, buffer->std.cmd_select, 39 buffer->std.input[0], buffer->std.input[1], 40 buffer->std.input[2], buffer->std.input[3], 41 buffer->std.output[0], buffer->std.output[1], 42 buffer->std.output[2], buffer->std.output[3]); 43 } 44 45 static int run_wmi_smbios_cmd(struct dell_wmi_smbios_buffer *buffer) 46 { 47 int fd; 48 int ret; 49 50 fd = open(ioctl_devfs, O_NONBLOCK); 51 ret = ioctl(fd, DELL_WMI_SMBIOS_CMD, buffer); 52 close(fd); 53 return ret; 54 } 55 56 static int find_token(__u16 token, __u16 *location, __u16 *value) 57 { 58 char location_sysfs[60]; 59 char value_sysfs[57]; 60 char buf[4096]; 61 FILE *f; 62 int ret; 63 64 ret = sprintf(value_sysfs, "%s/%04x_value", token_sysfs, token); 65 if (ret < 0) { 66 printf("sprintf value failed\n"); 67 return 2; 68 } 69 f = fopen(value_sysfs, "rb"); 70 if (!f) { 71 printf("failed to open %s\n", value_sysfs); 72 return 2; 73 } 74 fread(buf, 1, 4096, f); 75 fclose(f); 76 *value = (__u16) strtol(buf, NULL, 16); 77 78 ret = sprintf(location_sysfs, "%s/%04x_location", token_sysfs, token); 79 if (ret < 0) { 80 printf("sprintf location failed\n"); 81 return 1; 82 } 83 f = fopen(location_sysfs, "rb"); 84 if (!f) { 85 printf("failed to open %s\n", location_sysfs); 86 return 2; 87 } 88 fread(buf, 1, 4096, f); 89 fclose(f); 90 *location = (__u16) strtol(buf, NULL, 16); 91 92 if (*location) 93 return 0; 94 return 2; 95 } 96 97 static int token_is_active(__u16 *location, __u16 *cmpvalue, 98 struct dell_wmi_smbios_buffer *buffer) 99 { 100 int ret; 101 102 buffer->std.cmd_class = CLASS_TOKEN_READ; 103 buffer->std.cmd_select = SELECT_TOKEN_STD; 104 buffer->std.input[0] = *location; 105 ret = run_wmi_smbios_cmd(buffer); 106 if (ret != 0 || buffer->std.output[0] != 0) 107 return ret; 108 ret = (buffer->std.output[1] == *cmpvalue); 109 return ret; 110 } 111 112 static int query_token(__u16 token, struct dell_wmi_smbios_buffer *buffer) 113 { 114 __u16 location; 115 __u16 value; 116 int ret; 117 118 ret = find_token(token, &location, &value); 119 if (ret != 0) { 120 printf("unable to find token %04x\n", token); 121 return 1; 122 } 123 return token_is_active(&location, &value, buffer); 124 } 125 126 static int activate_token(struct dell_wmi_smbios_buffer *buffer, 127 __u16 token) 128 { 129 __u16 location; 130 __u16 value; 131 int ret; 132 133 ret = find_token(token, &location, &value); 134 if (ret != 0) { 135 printf("unable to find token %04x\n", token); 136 return 1; 137 } 138 buffer->std.cmd_class = CLASS_TOKEN_WRITE; 139 buffer->std.cmd_select = SELECT_TOKEN_STD; 140 buffer->std.input[0] = location; 141 buffer->std.input[1] = 1; 142 ret = run_wmi_smbios_cmd(buffer); 143 return ret; 144 } 145 146 static int query_buffer_size(__u64 *buffer_size) 147 { 148 FILE *f; 149 150 f = fopen(ioctl_devfs, "rb"); 151 if (!f) 152 return -EINVAL; 153 fread(buffer_size, sizeof(__u64), 1, f); 154 fclose(f); 155 return EXIT_SUCCESS; 156 } 157 158 int main(void) 159 { 160 struct dell_wmi_smbios_buffer *buffer; 161 int ret; 162 __u64 value = 0; 163 164 ret = query_buffer_size(&value); 165 if (ret == EXIT_FAILURE || !value) { 166 printf("Unable to read buffer size\n"); 167 goto out; 168 } 169 printf("Detected required buffer size %lld\n", value); 170 171 buffer = malloc(value); 172 if (buffer == NULL) { 173 printf("failed to alloc memory for ioctl\n"); 174 ret = -ENOMEM; 175 goto out; 176 } 177 buffer->length = value; 178 179 /* simple SMBIOS call for looking up TPM info */ 180 buffer->std.cmd_class = CLASS_FLASH_INTERFACE; 181 buffer->std.cmd_select = SELECT_FLASH_INTERFACE; 182 buffer->std.input[0] = 2; 183 ret = run_wmi_smbios_cmd(buffer); 184 if (ret) { 185 printf("smbios ioctl failed: %d\n", ret); 186 ret = EXIT_FAILURE; 187 goto out; 188 } 189 show_buffer(buffer); 190 191 /* query some tokens */ 192 ret = query_token(CAPSULE_EN_TOKEN, buffer); 193 printf("UEFI Capsule enabled token is: %d\n", ret); 194 ret = query_token(CAPSULE_DIS_TOKEN, buffer); 195 printf("UEFI Capsule disabled token is: %d\n", ret); 196 197 /* activate UEFI capsule token if disabled */ 198 if (ret) { 199 printf("Enabling UEFI capsule token"); 200 if (activate_token(buffer, CAPSULE_EN_TOKEN)) { 201 printf("activate failed\n"); 202 ret = -1; 203 goto out; 204 } 205 } 206 ret = EXIT_SUCCESS; 207 out: 208 free(buffer); 209 return ret; 210 } 211