sandbox: tpm: Add TPM emulation

Add a simple TPM emulator for sandbox. It only supports a small subset of
TPM operations. However, these are enough to perform common tasks.

Note this is an initial commit to get this working, but it could use
cleaning up (for example constants instead of open-coded values).

Signed-off-by: Simon Glass <sjg@chromium.org>

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>

2 files changed, 263 insertions, 0 deletions

diff --git a/drivers/tpm/Makefile b/drivers/tpm/Makefile
index 2f2353f809b..150570ee7e4 100644
--- a/drivers/tpm/Makefile
+++ b/drivers/tpm/Makefile
@@ -8,3 +8,4 @@ obj-$(CONFIG_TPM_ATMEL_TWI) += tpm_atmel_twi.o
 obj-$(CONFIG_TPM_TIS_I2C) += tpm.o
 obj-$(CONFIG_TPM_TIS_I2C) += tpm_tis_i2c.o
 obj-$(CONFIG_TPM_TIS_LPC) += tpm_tis_lpc.o
+obj-$(CONFIG_TPM_TIS_SANDBOX) += tpm_tis_sandbox.o
diff --git a/drivers/tpm/tpm_tis_sandbox.c b/drivers/tpm/tpm_tis_sandbox.c
new file mode 100644
index 00000000000..80cf734f1c2
--- /dev/null
+++ b/drivers/tpm/tpm_tis_sandbox.c
@@ -0,0 +1,262 @@
+/*
+ * Copyright (c) 2013 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <asm/state.h>
+#include <asm/unaligned.h>
+#include <linux/crc8.h>
+
+/* TPM NVRAM location indices. */
+#define FIRMWARE_NV_INDEX		0x1007
+#define KERNEL_NV_INDEX			0x1008
+
+#define NV_DATA_PUBLIC_PERMISSIONS_OFFSET	60
+
+/* Kernel TPM space - KERNEL_NV_INDEX, locked with physical presence */
+#define ROLLBACK_SPACE_KERNEL_VERSION	2
+#define ROLLBACK_SPACE_KERNEL_UID	0x4752574C  /* 'GRWL' */
+
+struct rollback_space_kernel {
+	/* Struct version, for backwards compatibility */
+	uint8_t struct_version;
+	/* Unique ID to detect space redefinition */
+	uint32_t uid;
+	/* Kernel versions */
+	uint32_t kernel_versions;
+	/* Reserved for future expansion */
+	uint8_t reserved[3];
+	/* Checksum (v2 and later only) */
+	uint8_t crc8;
+} __packed rollback_space_kernel;
+
+/*
+ * These numbers derive from adding the sizes of command fields as shown in
+ * the TPM commands manual.
+ */
+#define TPM_REQUEST_HEADER_LENGTH	10
+#define TPM_RESPONSE_HEADER_LENGTH	10
+
+/* These are the different non-volatile spaces that we emulate */
+enum {
+	NV_GLOBAL_LOCK,
+	NV_SEQ_FIRMWARE,
+	NV_SEQ_KERNEL,
+	NV_SEQ_COUNT,
+};
+
+/* Size of each non-volatile space */
+#define NV_DATA_SIZE		0x20
+
+/*
+ * Information about our TPM emulation. This is preserved in the sandbox
+ * state file if enabled.
+ */
+static struct tpm_state {
+	uint8_t nvdata[NV_SEQ_COUNT][NV_DATA_SIZE];
+} state;
+
+/**
+ * sandbox_tpm_read_state() - read the sandbox EC state from the state file
+ *
+ * If data is available, then blob and node will provide access to it. If
+ * not this function sets up an empty TPM.
+ *
+ * @blob: Pointer to device tree blob, or NULL if no data to read
+ * @node: Node offset to read from
+ */
+static int sandbox_tpm_read_state(const void *blob, int node)
+{
+	const char *prop;
+	int len;
+	int i;
+
+	if (!blob)
+		return 0;
+
+	for (i = 0; i < NV_SEQ_COUNT; i++) {
+		char prop_name[20];
+
+		sprintf(prop_name, "nvdata%d", i);
+		prop = fdt_getprop(blob, node, prop_name, &len);
+		if (prop && len == NV_DATA_SIZE)
+			memcpy(state.nvdata[i], prop, NV_DATA_SIZE);
+	}
+
+	return 0;
+}
+
+/**
+ * cros_ec_write_state() - Write out our state to the state file
+ *
+ * The caller will ensure that there is a node ready for the state. The node
+ * may already contain the old state, in which case it is overridden.
+ *
+ * @blob: Device tree blob holding state
+ * @node: Node to write our state into
+ */
+static int sandbox_tpm_write_state(void *blob, int node)
+{
+	int i;
+
+	/*
+	 * We are guaranteed enough space to write basic properties.
+	 * We could use fdt_add_subnode() to put each set of data in its
+	 * own node - perhaps useful if we add access informaiton to each.
+	 */
+	for (i = 0; i < NV_SEQ_COUNT; i++) {
+		char prop_name[20];
+
+		sprintf(prop_name, "nvdata%d", i);
+		fdt_setprop(blob, node, prop_name, state.nvdata[i],
+			    NV_DATA_SIZE);
+	}
+
+	return 0;
+}
+
+SANDBOX_STATE_IO(sandbox_tpm, "google,sandbox-tpm", sandbox_tpm_read_state,
+		 sandbox_tpm_write_state);
+
+static int index_to_seq(uint32_t index)
+{
+	switch (index) {
+	case FIRMWARE_NV_INDEX:
+		return NV_SEQ_FIRMWARE;
+	case KERNEL_NV_INDEX:
+		return NV_SEQ_KERNEL;
+	case 0:
+		return NV_GLOBAL_LOCK;
+	}
+
+	printf("Invalid nv index %#x\n", index);
+	return -1;
+}
+
+int tis_sendrecv(const u8 *sendbuf, size_t send_size,
+		 u8 *recvbuf, size_t *recv_len)
+{
+	struct tpm_state *tpm = &state;
+	uint32_t code, index, length, type;
+	uint8_t *data;
+	int seq;
+
+	code = get_unaligned_be32(sendbuf + sizeof(uint16_t) +
+				  sizeof(uint32_t));
+	printf("tpm: %zd bytes, recv_len %zd, cmd = %x\n", send_size,
+	       *recv_len, code);
+	print_buffer(0, sendbuf, 1, send_size, 0);
+	switch (code) {
+	case 0x65: /* get flags */
+		type = get_unaligned_be32(sendbuf + 14);
+		switch (type) {
+		case 4:
+			index = get_unaligned_be32(sendbuf + 18);
+			printf("Get flags index %#02x\n", index);
+			*recv_len = 22;
+			memset(recvbuf, '\0', *recv_len);
+			put_unaligned_be32(22, recvbuf +
+					   TPM_RESPONSE_HEADER_LENGTH);
+			data = recvbuf + TPM_RESPONSE_HEADER_LENGTH +
+					sizeof(uint32_t);
+			switch (index) {
+			case FIRMWARE_NV_INDEX:
+				break;
+			case KERNEL_NV_INDEX:
+				/* TPM_NV_PER_PPWRITE */
+				put_unaligned_be32(1, data +
+					NV_DATA_PUBLIC_PERMISSIONS_OFFSET);
+				break;
+			}
+			break;
+		case 0x11: /* TPM_CAP_NV_INDEX */
+			index = get_unaligned_be32(sendbuf + 18);
+			printf("Get cap nv index %#02x\n", index);
+			put_unaligned_be32(22, recvbuf +
+					   TPM_RESPONSE_HEADER_LENGTH);
+			break;
+		default:
+			printf("   ** Unknown 0x65 command type %#02x\n",
+			       type);
+			return -1;
+		}
+		break;
+	case 0xcd: /* nvwrite */
+		index = get_unaligned_be32(sendbuf + 10);
+		length = get_unaligned_be32(sendbuf + 18);
+		seq = index_to_seq(index);
+		if (seq < 0)
+			return -1;
+		printf("tpm: nvwrite index=%#02x, len=%#02x\n", index, length);
+		memcpy(&tpm->nvdata[seq],
+		       recvbuf + TPM_RESPONSE_HEADER_LENGTH + sizeof(uint32_t),
+		       length);
+		*recv_len = 12;
+		memset(recvbuf, '\0', *recv_len);
+		break;
+	case 0xcf: /* nvread */
+		index = get_unaligned_be32(sendbuf + 10);
+		length = get_unaligned_be32(sendbuf + 18);
+		seq = index_to_seq(index);
+		if (seq < 0)
+			return -1;
+		printf("tpm: nvread index=%#02x, len=%#02x\n", index, length);
+		*recv_len = TPM_RESPONSE_HEADER_LENGTH + sizeof(uint32_t) +
+					length;
+		memset(recvbuf, '\0', *recv_len);
+		put_unaligned_be32(length, recvbuf +
+				   TPM_RESPONSE_HEADER_LENGTH);
+		if (seq == NV_SEQ_KERNEL) {
+			struct rollback_space_kernel rsk;
+
+			data = recvbuf + TPM_RESPONSE_HEADER_LENGTH +
+					sizeof(uint32_t);
+			rsk.struct_version = 2;
+			rsk.uid = ROLLBACK_SPACE_KERNEL_UID;
+			rsk.kernel_versions = 0;
+			rsk.crc8 = crc8((unsigned char *)&rsk,
+					offsetof(struct rollback_space_kernel,
+						 crc8));
+			memcpy(data, &rsk, sizeof(rsk));
+		} else {
+			memcpy(recvbuf + TPM_RESPONSE_HEADER_LENGTH +
+			       sizeof(uint32_t), &tpm->nvdata[seq], length);
+		}
+		break;
+	case 0x14: /* tpm extend */
+	case 0x15: /* pcr read */
+	case 0x5d: /* force clear */
+	case 0x6f: /* physical enable */
+	case 0x72: /* physical set deactivated */
+	case 0x99: /* startup */
+	case 0x4000000a:  /* assert physical presence */
+		*recv_len = 12;
+		memset(recvbuf, '\0', *recv_len);
+		break;
+	default:
+		printf("Unknown tpm command %02x\n", code);
+		return -1;
+	}
+
+	return 0;
+}
+
+int tis_open(void)
+{
+	printf("%s\n", __func__);
+	return 0;
+}
+
+int tis_close(void)
+{
+	printf("%s\n", __func__);
+	return 0;
+}
+
+int tis_init(void)
+{
+	printf("%s\n", __func__);
+	return 0;
+}