xref: /openbmc/linux/drivers/char/tpm/tpm_ppi.c (revision b34e08d5)
1 #include <linux/acpi.h>
2 #include "tpm.h"
3 
4 #define TPM_PPI_REVISION_ID	1
5 #define TPM_PPI_FN_VERSION	1
6 #define TPM_PPI_FN_SUBREQ	2
7 #define TPM_PPI_FN_GETREQ	3
8 #define TPM_PPI_FN_GETACT	4
9 #define TPM_PPI_FN_GETRSP	5
10 #define TPM_PPI_FN_SUBREQ2	7
11 #define TPM_PPI_FN_GETOPR	8
12 #define PPI_TPM_REQ_MAX		22
13 #define PPI_VS_REQ_START	128
14 #define PPI_VS_REQ_END		255
15 #define PPI_VERSION_LEN		3
16 
17 static const u8 tpm_ppi_uuid[] = {
18 	0xA6, 0xFA, 0xDD, 0x3D,
19 	0x1B, 0x36,
20 	0xB4, 0x4E,
21 	0xA4, 0x24,
22 	0x8D, 0x10, 0x08, 0x9D, 0x16, 0x53
23 };
24 
25 static char tpm_ppi_version[PPI_VERSION_LEN + 1];
26 static acpi_handle tpm_ppi_handle;
27 
28 static acpi_status ppi_callback(acpi_handle handle, u32 level, void *context,
29 				void **return_value)
30 {
31 	union acpi_object *obj;
32 
33 	if (!acpi_check_dsm(handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
34 			    1 << TPM_PPI_FN_VERSION))
35 		return AE_OK;
36 
37 	/* Cache version string */
38 	obj = acpi_evaluate_dsm_typed(handle, tpm_ppi_uuid,
39 				      TPM_PPI_REVISION_ID, TPM_PPI_FN_VERSION,
40 				      NULL, ACPI_TYPE_STRING);
41 	if (obj) {
42 		strlcpy(tpm_ppi_version, obj->string.pointer,
43 			PPI_VERSION_LEN + 1);
44 		ACPI_FREE(obj);
45 	}
46 
47 	*return_value = handle;
48 
49 	return AE_CTRL_TERMINATE;
50 }
51 
52 static inline union acpi_object *
53 tpm_eval_dsm(int func, acpi_object_type type, union acpi_object *argv4)
54 {
55 	BUG_ON(!tpm_ppi_handle);
56 	return acpi_evaluate_dsm_typed(tpm_ppi_handle, tpm_ppi_uuid,
57 				       TPM_PPI_REVISION_ID, func, argv4, type);
58 }
59 
60 static ssize_t tpm_show_ppi_version(struct device *dev,
61 				    struct device_attribute *attr, char *buf)
62 {
63 	return scnprintf(buf, PAGE_SIZE, "%s\n", tpm_ppi_version);
64 }
65 
66 static ssize_t tpm_show_ppi_request(struct device *dev,
67 				    struct device_attribute *attr, char *buf)
68 {
69 	ssize_t size = -EINVAL;
70 	union acpi_object *obj;
71 
72 	obj = tpm_eval_dsm(TPM_PPI_FN_GETREQ, ACPI_TYPE_PACKAGE, NULL);
73 	if (!obj)
74 		return -ENXIO;
75 
76 	/*
77 	 * output.pointer should be of package type, including two integers.
78 	 * The first is function return code, 0 means success and 1 means
79 	 * error. The second is pending TPM operation requested by the OS, 0
80 	 * means none and >0 means operation value.
81 	 */
82 	if (obj->package.count == 2 &&
83 	    obj->package.elements[0].type == ACPI_TYPE_INTEGER &&
84 	    obj->package.elements[1].type == ACPI_TYPE_INTEGER) {
85 		if (obj->package.elements[0].integer.value)
86 			size = -EFAULT;
87 		else
88 			size = scnprintf(buf, PAGE_SIZE, "%llu\n",
89 				 obj->package.elements[1].integer.value);
90 	}
91 
92 	ACPI_FREE(obj);
93 
94 	return size;
95 }
96 
97 static ssize_t tpm_store_ppi_request(struct device *dev,
98 				     struct device_attribute *attr,
99 				     const char *buf, size_t count)
100 {
101 	u32 req;
102 	u64 ret;
103 	int func = TPM_PPI_FN_SUBREQ;
104 	union acpi_object *obj, tmp;
105 	union acpi_object argv4 = ACPI_INIT_DSM_ARGV4(1, &tmp);
106 
107 	/*
108 	 * the function to submit TPM operation request to pre-os environment
109 	 * is updated with function index from SUBREQ to SUBREQ2 since PPI
110 	 * version 1.1
111 	 */
112 	if (acpi_check_dsm(tpm_ppi_handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
113 			   1 << TPM_PPI_FN_SUBREQ2))
114 		func = TPM_PPI_FN_SUBREQ2;
115 
116 	/*
117 	 * PPI spec defines params[3].type as ACPI_TYPE_PACKAGE. Some BIOS
118 	 * accept buffer/string/integer type, but some BIOS accept buffer/
119 	 * string/package type. For PPI version 1.0 and 1.1, use buffer type
120 	 * for compatibility, and use package type since 1.2 according to spec.
121 	 */
122 	if (strcmp(tpm_ppi_version, "1.2") < 0) {
123 		if (sscanf(buf, "%d", &req) != 1)
124 			return -EINVAL;
125 		argv4.type = ACPI_TYPE_BUFFER;
126 		argv4.buffer.length = sizeof(req);
127 		argv4.buffer.pointer = (u8 *)&req;
128 	} else {
129 		tmp.type = ACPI_TYPE_INTEGER;
130 		if (sscanf(buf, "%llu", &tmp.integer.value) != 1)
131 			return -EINVAL;
132 	}
133 
134 	obj = tpm_eval_dsm(func, ACPI_TYPE_INTEGER, &argv4);
135 	if (!obj) {
136 		return -ENXIO;
137 	} else {
138 		ret = obj->integer.value;
139 		ACPI_FREE(obj);
140 	}
141 
142 	if (ret == 0)
143 		return (acpi_status)count;
144 
145 	return (ret == 1) ? -EPERM : -EFAULT;
146 }
147 
148 static ssize_t tpm_show_ppi_transition_action(struct device *dev,
149 					      struct device_attribute *attr,
150 					      char *buf)
151 {
152 	u32 ret;
153 	acpi_status status;
154 	union acpi_object *obj = NULL;
155 	union acpi_object tmp = {
156 		.buffer.type = ACPI_TYPE_BUFFER,
157 		.buffer.length = 0,
158 		.buffer.pointer = NULL
159 	};
160 
161 	static char *info[] = {
162 		"None",
163 		"Shutdown",
164 		"Reboot",
165 		"OS Vendor-specific",
166 		"Error",
167 	};
168 
169 	/*
170 	 * PPI spec defines params[3].type as empty package, but some platforms
171 	 * (e.g. Capella with PPI 1.0) need integer/string/buffer type, so for
172 	 * compatibility, define params[3].type as buffer, if PPI version < 1.2
173 	 */
174 	if (strcmp(tpm_ppi_version, "1.2") < 0)
175 		obj = &tmp;
176 	obj = tpm_eval_dsm(TPM_PPI_FN_GETACT, ACPI_TYPE_INTEGER, obj);
177 	if (!obj) {
178 		return -ENXIO;
179 	} else {
180 		ret = obj->integer.value;
181 		ACPI_FREE(obj);
182 	}
183 
184 	if (ret < ARRAY_SIZE(info) - 1)
185 		status = scnprintf(buf, PAGE_SIZE, "%d: %s\n", ret, info[ret]);
186 	else
187 		status = scnprintf(buf, PAGE_SIZE, "%d: %s\n", ret,
188 				   info[ARRAY_SIZE(info)-1]);
189 	return status;
190 }
191 
192 static ssize_t tpm_show_ppi_response(struct device *dev,
193 				     struct device_attribute *attr,
194 				     char *buf)
195 {
196 	acpi_status status = -EINVAL;
197 	union acpi_object *obj, *ret_obj;
198 	u64 req, res;
199 
200 	obj = tpm_eval_dsm(TPM_PPI_FN_GETRSP, ACPI_TYPE_PACKAGE, NULL);
201 	if (!obj)
202 		return -ENXIO;
203 
204 	/*
205 	 * parameter output.pointer should be of package type, including
206 	 * 3 integers. The first means function return code, the second means
207 	 * most recent TPM operation request, and the last means response to
208 	 * the most recent TPM operation request. Only if the first is 0, and
209 	 * the second integer is not 0, the response makes sense.
210 	 */
211 	ret_obj = obj->package.elements;
212 	if (obj->package.count < 3 ||
213 	    ret_obj[0].type != ACPI_TYPE_INTEGER ||
214 	    ret_obj[1].type != ACPI_TYPE_INTEGER ||
215 	    ret_obj[2].type != ACPI_TYPE_INTEGER)
216 		goto cleanup;
217 
218 	if (ret_obj[0].integer.value) {
219 		status = -EFAULT;
220 		goto cleanup;
221 	}
222 
223 	req = ret_obj[1].integer.value;
224 	res = ret_obj[2].integer.value;
225 	if (req) {
226 		if (res == 0)
227 			status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
228 					   "0: Success");
229 		else if (res == 0xFFFFFFF0)
230 			status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
231 					   "0xFFFFFFF0: User Abort");
232 		else if (res == 0xFFFFFFF1)
233 			status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
234 					   "0xFFFFFFF1: BIOS Failure");
235 		else if (res >= 1 && res <= 0x00000FFF)
236 			status = scnprintf(buf, PAGE_SIZE, "%llu %llu: %s\n",
237 					   req, res, "Corresponding TPM error");
238 		else
239 			status = scnprintf(buf, PAGE_SIZE, "%llu %llu: %s\n",
240 					   req, res, "Error");
241 	} else {
242 		status = scnprintf(buf, PAGE_SIZE, "%llu: %s\n",
243 				   req, "No Recent Request");
244 	}
245 
246 cleanup:
247 	ACPI_FREE(obj);
248 	return status;
249 }
250 
251 static ssize_t show_ppi_operations(char *buf, u32 start, u32 end)
252 {
253 	int i;
254 	u32 ret;
255 	char *str = buf;
256 	union acpi_object *obj, tmp;
257 	union acpi_object argv = ACPI_INIT_DSM_ARGV4(1, &tmp);
258 
259 	static char *info[] = {
260 		"Not implemented",
261 		"BIOS only",
262 		"Blocked for OS by BIOS",
263 		"User required",
264 		"User not required",
265 	};
266 
267 	if (!acpi_check_dsm(tpm_ppi_handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
268 			    1 << TPM_PPI_FN_GETOPR))
269 		return -EPERM;
270 
271 	tmp.integer.type = ACPI_TYPE_INTEGER;
272 	for (i = start; i <= end; i++) {
273 		tmp.integer.value = i;
274 		obj = tpm_eval_dsm(TPM_PPI_FN_GETOPR, ACPI_TYPE_INTEGER, &argv);
275 		if (!obj) {
276 			return -ENOMEM;
277 		} else {
278 			ret = obj->integer.value;
279 			ACPI_FREE(obj);
280 		}
281 
282 		if (ret > 0 && ret < ARRAY_SIZE(info))
283 			str += scnprintf(str, PAGE_SIZE, "%d %d: %s\n",
284 					 i, ret, info[ret]);
285 	}
286 
287 	return str - buf;
288 }
289 
290 static ssize_t tpm_show_ppi_tcg_operations(struct device *dev,
291 					   struct device_attribute *attr,
292 					   char *buf)
293 {
294 	return show_ppi_operations(buf, 0, PPI_TPM_REQ_MAX);
295 }
296 
297 static ssize_t tpm_show_ppi_vs_operations(struct device *dev,
298 					  struct device_attribute *attr,
299 					  char *buf)
300 {
301 	return show_ppi_operations(buf, PPI_VS_REQ_START, PPI_VS_REQ_END);
302 }
303 
304 static DEVICE_ATTR(version, S_IRUGO, tpm_show_ppi_version, NULL);
305 static DEVICE_ATTR(request, S_IRUGO | S_IWUSR | S_IWGRP,
306 		   tpm_show_ppi_request, tpm_store_ppi_request);
307 static DEVICE_ATTR(transition_action, S_IRUGO,
308 		   tpm_show_ppi_transition_action, NULL);
309 static DEVICE_ATTR(response, S_IRUGO, tpm_show_ppi_response, NULL);
310 static DEVICE_ATTR(tcg_operations, S_IRUGO, tpm_show_ppi_tcg_operations, NULL);
311 static DEVICE_ATTR(vs_operations, S_IRUGO, tpm_show_ppi_vs_operations, NULL);
312 
313 static struct attribute *ppi_attrs[] = {
314 	&dev_attr_version.attr,
315 	&dev_attr_request.attr,
316 	&dev_attr_transition_action.attr,
317 	&dev_attr_response.attr,
318 	&dev_attr_tcg_operations.attr,
319 	&dev_attr_vs_operations.attr, NULL,
320 };
321 static struct attribute_group ppi_attr_grp = {
322 	.name = "ppi",
323 	.attrs = ppi_attrs
324 };
325 
326 int tpm_add_ppi(struct kobject *parent)
327 {
328 	/* Cache TPM ACPI handle and version string */
329 	acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT, ACPI_UINT32_MAX,
330 			    ppi_callback, NULL, NULL, &tpm_ppi_handle);
331 	if (tpm_ppi_handle == NULL)
332 		return -ENODEV;
333 
334 	return sysfs_create_group(parent, &ppi_attr_grp);
335 }
336 
337 void tpm_remove_ppi(struct kobject *parent)
338 {
339 	sysfs_remove_group(parent, &ppi_attr_grp);
340 }
341