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
show_buffer(struct dell_wmi_smbios_buffer * buffer)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
run_wmi_smbios_cmd(struct dell_wmi_smbios_buffer * buffer)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
find_token(__u16 token,__u16 * location,__u16 * value)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
token_is_active(__u16 * location,__u16 * cmpvalue,struct dell_wmi_smbios_buffer * buffer)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
query_token(__u16 token,struct dell_wmi_smbios_buffer * buffer)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
activate_token(struct dell_wmi_smbios_buffer * buffer,__u16 token)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
query_buffer_size(__u64 * buffer_size)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
main(void)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
