1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Copyright (c) 2013 Google, Inc
4  */
5 
6 #include <common.h>
7 #include <dm.h>
8 #include <tpm-v1.h>
9 #include <asm/state.h>
10 #include <asm/unaligned.h>
11 #include <linux/crc8.h>
12 
13 /* TPM NVRAM location indices. */
14 #define FIRMWARE_NV_INDEX		0x1007
15 #define KERNEL_NV_INDEX			0x1008
16 #define BACKUP_NV_INDEX                 0x1009
17 #define FWMP_NV_INDEX                   0x100a
18 #define REC_HASH_NV_INDEX               0x100b
19 #define REC_HASH_NV_SIZE                VB2_SHA256_DIGEST_SIZE
20 
21 #define NV_DATA_PUBLIC_PERMISSIONS_OFFSET	60
22 
23 /* Kernel TPM space - KERNEL_NV_INDEX, locked with physical presence */
24 #define ROLLBACK_SPACE_KERNEL_VERSION	2
25 #define ROLLBACK_SPACE_KERNEL_UID	0x4752574C  /* 'GRWL' */
26 
27 struct rollback_space_kernel {
28 	/* Struct version, for backwards compatibility */
29 	uint8_t struct_version;
30 	/* Unique ID to detect space redefinition */
31 	uint32_t uid;
32 	/* Kernel versions */
33 	uint32_t kernel_versions;
34 	/* Reserved for future expansion */
35 	uint8_t reserved[3];
36 	/* Checksum (v2 and later only) */
37 	uint8_t crc8;
38 } __packed rollback_space_kernel;
39 
40 /*
41  * These numbers derive from adding the sizes of command fields as shown in
42  * the TPM commands manual.
43  */
44 #define TPM_REQUEST_HEADER_LENGTH	10
45 #define TPM_RESPONSE_HEADER_LENGTH	10
46 
47 /* These are the different non-volatile spaces that we emulate */
48 enum {
49 	NV_GLOBAL_LOCK,
50 	NV_SEQ_FIRMWARE,
51 	NV_SEQ_KERNEL,
52 	NV_SEQ_BACKUP,
53 	NV_SEQ_FWMP,
54 	NV_SEQ_REC_HASH,
55 
56 	NV_SEQ_COUNT,
57 };
58 
59 /* Size of each non-volatile space */
60 #define NV_DATA_SIZE		0x20
61 
62 struct nvdata_state {
63 	bool present;
64 	u8 data[NV_DATA_SIZE];
65 };
66 
67 /*
68  * Information about our TPM emulation. This is preserved in the sandbox
69  * state file if enabled.
70  */
71 static struct tpm_state {
72 	bool valid;
73 	struct nvdata_state nvdata[NV_SEQ_COUNT];
74 } g_state;
75 
76 /**
77  * sandbox_tpm_read_state() - read the sandbox EC state from the state file
78  *
79  * If data is available, then blob and node will provide access to it. If
80  * not this function sets up an empty TPM.
81  *
82  * @blob: Pointer to device tree blob, or NULL if no data to read
83  * @node: Node offset to read from
84  */
sandbox_tpm_read_state(const void * blob,int node)85 static int sandbox_tpm_read_state(const void *blob, int node)
86 {
87 	const char *prop;
88 	int len;
89 	int i;
90 
91 	if (!blob)
92 		return 0;
93 
94 	for (i = 0; i < NV_SEQ_COUNT; i++) {
95 		char prop_name[20];
96 
97 		sprintf(prop_name, "nvdata%d", i);
98 		prop = fdt_getprop(blob, node, prop_name, &len);
99 		if (prop && len == NV_DATA_SIZE) {
100 			memcpy(g_state.nvdata[i].data, prop, NV_DATA_SIZE);
101 			g_state.nvdata[i].present = true;
102 		}
103 	}
104 	g_state.valid = true;
105 
106 	return 0;
107 }
108 
109 /**
110  * cros_ec_write_state() - Write out our state to the state file
111  *
112  * The caller will ensure that there is a node ready for the state. The node
113  * may already contain the old state, in which case it is overridden.
114  *
115  * @blob: Device tree blob holding state
116  * @node: Node to write our state into
117  */
sandbox_tpm_write_state(void * blob,int node)118 static int sandbox_tpm_write_state(void *blob, int node)
119 {
120 	int i;
121 
122 	/*
123 	 * We are guaranteed enough space to write basic properties.
124 	 * We could use fdt_add_subnode() to put each set of data in its
125 	 * own node - perhaps useful if we add access informaiton to each.
126 	 */
127 	for (i = 0; i < NV_SEQ_COUNT; i++) {
128 		char prop_name[20];
129 
130 		if (g_state.nvdata[i].present) {
131 			sprintf(prop_name, "nvdata%d", i);
132 			fdt_setprop(blob, node, prop_name,
133 				    g_state.nvdata[i].data, NV_DATA_SIZE);
134 		}
135 	}
136 
137 	return 0;
138 }
139 
140 SANDBOX_STATE_IO(sandbox_tpm, "google,sandbox-tpm", sandbox_tpm_read_state,
141 		 sandbox_tpm_write_state);
142 
index_to_seq(uint32_t index)143 static int index_to_seq(uint32_t index)
144 {
145 	switch (index) {
146 	case FIRMWARE_NV_INDEX:
147 		return NV_SEQ_FIRMWARE;
148 	case KERNEL_NV_INDEX:
149 		return NV_SEQ_KERNEL;
150 	case BACKUP_NV_INDEX:
151 		return NV_SEQ_BACKUP;
152 	case FWMP_NV_INDEX:
153 		return NV_SEQ_FWMP;
154 	case REC_HASH_NV_INDEX:
155 		return NV_SEQ_REC_HASH;
156 	case 0:
157 		return NV_GLOBAL_LOCK;
158 	}
159 
160 	printf("Invalid nv index %#x\n", index);
161 	return -1;
162 }
163 
handle_cap_flag_space(u8 ** datap,uint index)164 static void handle_cap_flag_space(u8 **datap, uint index)
165 {
166 	struct tpm_nv_data_public pub;
167 
168 	/* TPM_NV_PER_PPWRITE */
169 	memset(&pub, '\0', sizeof(pub));
170 	pub.nv_index = __cpu_to_be32(index);
171 	pub.pcr_info_read.pcr_selection.size_of_select = __cpu_to_be16(
172 		sizeof(pub.pcr_info_read.pcr_selection.pcr_select));
173 	pub.permission.attributes = __cpu_to_be32(1);
174 	pub.pcr_info_write = pub.pcr_info_read;
175 	memcpy(*datap, &pub, sizeof(pub));
176 	*datap += sizeof(pub);
177 }
178 
sandbox_tpm_xfer(struct udevice * dev,const uint8_t * sendbuf,size_t send_size,uint8_t * recvbuf,size_t * recv_len)179 static int sandbox_tpm_xfer(struct udevice *dev, const uint8_t *sendbuf,
180 			    size_t send_size, uint8_t *recvbuf,
181 			    size_t *recv_len)
182 {
183 	struct tpm_state *tpm = dev_get_priv(dev);
184 	uint32_t code, index, length, type;
185 	uint8_t *data;
186 	int seq;
187 
188 	code = get_unaligned_be32(sendbuf + sizeof(uint16_t) +
189 				  sizeof(uint32_t));
190 #ifdef DEBUG
191 	printf("tpm: %zd bytes, recv_len %zd, cmd = %x\n", send_size,
192 	       *recv_len, code);
193 	print_buffer(0, sendbuf, 1, send_size, 0);
194 #endif
195 	switch (code) {
196 	case TPM_CMD_GET_CAPABILITY:
197 		type = get_unaligned_be32(sendbuf + 14);
198 		switch (type) {
199 		case TPM_CAP_FLAG:
200 			index = get_unaligned_be32(sendbuf + 18);
201 			printf("Get flags index %#02x\n", index);
202 			*recv_len = 22;
203 			memset(recvbuf, '\0', *recv_len);
204 			data = recvbuf + TPM_RESPONSE_HEADER_LENGTH +
205 					sizeof(uint32_t);
206 			switch (index) {
207 			case FIRMWARE_NV_INDEX:
208 				break;
209 			case KERNEL_NV_INDEX:
210 				handle_cap_flag_space(&data, index);
211 				*recv_len = data - recvbuf -
212 					TPM_RESPONSE_HEADER_LENGTH -
213 					sizeof(uint32_t);
214 				break;
215 			case TPM_CAP_FLAG_PERMANENT: {
216 				struct tpm_permanent_flags *pflags;
217 
218 				pflags = (struct tpm_permanent_flags *)data;
219 				memset(pflags, '\0', sizeof(*pflags));
220 				put_unaligned_be32(TPM_TAG_PERMANENT_FLAGS,
221 						   &pflags->tag);
222 				*recv_len = TPM_HEADER_SIZE + 4 +
223 						sizeof(*pflags);
224 				break;
225 			}
226 			default:
227 				printf("   ** Unknown flags index %x\n", index);
228 				return -ENOSYS;
229 			}
230 			put_unaligned_be32(*recv_len,
231 					   recvbuf +
232 					   TPM_RESPONSE_HEADER_LENGTH);
233 			break;
234 		case TPM_CAP_NV_INDEX:
235 			index = get_unaligned_be32(sendbuf + 18);
236 			printf("Get cap nv index %#02x\n", index);
237 			put_unaligned_be32(22, recvbuf +
238 					   TPM_RESPONSE_HEADER_LENGTH);
239 			break;
240 		default:
241 			printf("   ** Unknown 0x65 command type %#02x\n",
242 			       type);
243 			return -ENOSYS;
244 		}
245 		break;
246 	case TPM_CMD_NV_WRITE_VALUE:
247 		index = get_unaligned_be32(sendbuf + 10);
248 		length = get_unaligned_be32(sendbuf + 18);
249 		seq = index_to_seq(index);
250 		if (seq < 0)
251 			return -EINVAL;
252 		printf("tpm: nvwrite index=%#02x, len=%#02x\n", index, length);
253 		memcpy(&tpm->nvdata[seq].data, sendbuf + 22, length);
254 		tpm->nvdata[seq].present = true;
255 		*recv_len = 12;
256 		memset(recvbuf, '\0', *recv_len);
257 		break;
258 	case TPM_CMD_NV_READ_VALUE: /* nvread */
259 		index = get_unaligned_be32(sendbuf + 10);
260 		length = get_unaligned_be32(sendbuf + 18);
261 		seq = index_to_seq(index);
262 		if (seq < 0)
263 			return -EINVAL;
264 		printf("tpm: nvread index=%#02x, len=%#02x, seq=%#02x\n", index,
265 		       length, seq);
266 		*recv_len = TPM_RESPONSE_HEADER_LENGTH + sizeof(uint32_t) +
267 					length;
268 		memset(recvbuf, '\0', *recv_len);
269 		put_unaligned_be32(length, recvbuf +
270 				   TPM_RESPONSE_HEADER_LENGTH);
271 		if (seq == NV_SEQ_KERNEL) {
272 			struct rollback_space_kernel rsk;
273 
274 			data = recvbuf + TPM_RESPONSE_HEADER_LENGTH +
275 					sizeof(uint32_t);
276 			memset(&rsk, 0, sizeof(struct rollback_space_kernel));
277 			rsk.struct_version = 2;
278 			rsk.uid = ROLLBACK_SPACE_KERNEL_UID;
279 			rsk.crc8 = crc8(0, (unsigned char *)&rsk,
280 					offsetof(struct rollback_space_kernel,
281 						 crc8));
282 			memcpy(data, &rsk, sizeof(rsk));
283 		} else if (!tpm->nvdata[seq].present) {
284 			put_unaligned_be32(TPM_BADINDEX, recvbuf +
285 					   sizeof(uint16_t) + sizeof(uint32_t));
286 		} else {
287 			memcpy(recvbuf + TPM_RESPONSE_HEADER_LENGTH +
288 			       sizeof(uint32_t), &tpm->nvdata[seq].data,
289 			       length);
290 		}
291 		break;
292 	case TPM_CMD_EXTEND:
293 		*recv_len = 30;
294 		memset(recvbuf, '\0', *recv_len);
295 		break;
296 	case TPM_CMD_NV_DEFINE_SPACE:
297 	case 0x15: /* pcr read */
298 	case 0x5d: /* force clear */
299 	case 0x6f: /* physical enable */
300 	case 0x72: /* physical set deactivated */
301 	case 0x99: /* startup */
302 	case 0x50: /* self test full */
303 	case 0x4000000a:  /* assert physical presence */
304 		*recv_len = 12;
305 		memset(recvbuf, '\0', *recv_len);
306 		break;
307 	default:
308 		printf("Unknown tpm command %02x\n", code);
309 		return -ENOSYS;
310 	}
311 #ifdef DEBUG
312 	printf("tpm: rx recv_len %zd\n", *recv_len);
313 	print_buffer(0, recvbuf, 1, *recv_len, 0);
314 #endif
315 
316 	return 0;
317 }
318 
sandbox_tpm_get_desc(struct udevice * dev,char * buf,int size)319 static int sandbox_tpm_get_desc(struct udevice *dev, char *buf, int size)
320 {
321 	if (size < 15)
322 		return -ENOSPC;
323 
324 	return snprintf(buf, size, "sandbox TPM");
325 }
326 
sandbox_tpm_probe(struct udevice * dev)327 static int sandbox_tpm_probe(struct udevice *dev)
328 {
329 	struct tpm_state *tpm = dev_get_priv(dev);
330 
331 	memcpy(tpm, &g_state, sizeof(*tpm));
332 
333 	return 0;
334 }
335 
sandbox_tpm_open(struct udevice * dev)336 static int sandbox_tpm_open(struct udevice *dev)
337 {
338 	return 0;
339 }
340 
sandbox_tpm_close(struct udevice * dev)341 static int sandbox_tpm_close(struct udevice *dev)
342 {
343 	return 0;
344 }
345 
346 static const struct tpm_ops sandbox_tpm_ops = {
347 	.open		= sandbox_tpm_open,
348 	.close		= sandbox_tpm_close,
349 	.get_desc	= sandbox_tpm_get_desc,
350 	.xfer		= sandbox_tpm_xfer,
351 };
352 
353 static const struct udevice_id sandbox_tpm_ids[] = {
354 	{ .compatible = "google,sandbox-tpm" },
355 	{ }
356 };
357 
358 U_BOOT_DRIVER(sandbox_tpm) = {
359 	.name   = "sandbox_tpm",
360 	.id     = UCLASS_TPM,
361 	.of_match = sandbox_tpm_ids,
362 	.ops    = &sandbox_tpm_ops,
363 	.probe	= sandbox_tpm_probe,
364 	.priv_auto_alloc_size = sizeof(struct tpm_state),
365 };
366