[PATCH] tpm2: ftpm: A driver for firmware TPM running inside TEE
Thirupathaiah Annapureddy
thiruan at linux.microsoft.com
Mon Jan 13 08:34:22 CET 2020
Add a driver for a firmware TPM running inside TEE.
Documentation of the firmware TPM:
https://www.microsoft.com/en-us/research/publication/ftpm-software-implementation-tpm-chip/
Implementation of the firmware TPM:
https://github.com/Microsoft/ms-tpm-20-ref/tree/master/Samples/ARM32-FirmwareTPM
Signed-off-by: Thirupathaiah Annapureddy <thiruan at linux.microsoft.com>
---
drivers/tpm/Kconfig | 6 +
drivers/tpm/Makefile | 1 +
drivers/tpm/tpm2_ftpm_tee.c | 250 ++++++++++++++++++++++++++++++++++++
drivers/tpm/tpm2_ftpm_tee.h | 35 +++++
4 files changed, 292 insertions(+)
create mode 100644 drivers/tpm/tpm2_ftpm_tee.c
create mode 100644 drivers/tpm/tpm2_ftpm_tee.h
diff --git a/drivers/tpm/Kconfig b/drivers/tpm/Kconfig
index 94629dffd2..81bbffc50d 100644
--- a/drivers/tpm/Kconfig
+++ b/drivers/tpm/Kconfig
@@ -145,6 +145,12 @@ config TPM2_TIS_SPI
to the device using the standard TPM Interface Specification (TIS)
protocol.
+config TPM2_FTPM_TEE
+ bool "TEE based fTPM Interface"
+ depends on TEE && OPTEE && TPM_V2
+ help
+ This driver supports firmware TPM running in TEE.
+
endif # TPM_V2
endmenu
diff --git a/drivers/tpm/Makefile b/drivers/tpm/Makefile
index 94c337b8ed..b1be3feac8 100644
--- a/drivers/tpm/Makefile
+++ b/drivers/tpm/Makefile
@@ -12,3 +12,4 @@ obj-$(CONFIG_TPM_ST33ZP24_SPI) += tpm_tis_st33zp24_spi.o
obj-$(CONFIG_TPM2_TIS_SANDBOX) += tpm2_tis_sandbox.o
obj-$(CONFIG_TPM2_TIS_SPI) += tpm2_tis_spi.o
+obj-$(CONFIG_TPM2_FTPM_TEE) += tpm2_ftpm_tee.o
diff --git a/drivers/tpm/tpm2_ftpm_tee.c b/drivers/tpm/tpm2_ftpm_tee.c
new file mode 100644
index 0000000000..4b79d4ada0
--- /dev/null
+++ b/drivers/tpm/tpm2_ftpm_tee.c
@@ -0,0 +1,250 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) Microsoft Corporation
+ *
+ * Authors:
+ * Thirupathaiah Annapureddy <thiruan at microsoft.com>
+ *
+ * Description:
+ * Device Driver for a firmware TPM as described here:
+ * https://www.microsoft.com/en-us/research/publication/ftpm-software-implementation-tpm-chip/
+ *
+ * A reference implementation is available here:
+ * https://github.com/microsoft/ms-tpm-20-ref/tree/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <tpm-v2.h>
+#include <tee.h>
+
+#include "tpm_tis.h"
+#include "tpm2_ftpm_tee.h"
+
+/**
+ * ftpm_tee_transceive() - send fTPM commands and retrieve fTPM response.
+ * @sendbuf - address of the data to send, byte by byte
+ * @send_size - length of the data to send
+ * @recvbuf - address where to read the response, byte by byte.
+ * @recv_len - pointer to the size of buffer
+ *
+ * Return:
+ * In case of success, returns 0.
+ * On failure, -errno
+ */
+static int ftpm_tee_transceive(struct udevice *dev, const u8 *sendbuf,
+ size_t send_size, u8 *recvbuf,
+ size_t *recv_len)
+{
+ struct ftpm_tee_private *context = dev_get_priv(dev);
+ int rc = 0;
+ size_t resp_len;
+ u8 *resp_buf;
+ struct tpm_output_header *resp_header;
+ struct tee_invoke_arg transceive_args;
+ struct tee_param command_params[4];
+ struct tee_shm *shm;
+
+ if (send_size > MAX_COMMAND_SIZE) {
+ debug("%s:send_size=%zd exceeds MAX_COMMAND_SIZE\n",
+ __func__, send_size);
+ return -EIO;
+ }
+
+ shm = context->shm;
+ memset(&transceive_args, 0, sizeof(transceive_args));
+ memset(command_params, 0, sizeof(command_params));
+
+ /* Invoke FTPM_OPTEE_TA_SUBMIT_COMMAND function of fTPM TA */
+ transceive_args = (struct tee_invoke_arg) {
+ .func = FTPM_OPTEE_TA_SUBMIT_COMMAND,
+ .session = context->session,
+ };
+
+ /* Fill FTPM_OPTEE_TA_SUBMIT_COMMAND parameters */
+ /* request */
+ command_params[0] = (struct tee_param) {
+ .attr = TEE_PARAM_ATTR_TYPE_MEMREF_INPUT,
+ .u.memref = {
+ .shm = shm,
+ .size = send_size,
+ .shm_offs = 0,
+ },
+ };
+ memset(command_params[0].u.memref.shm->addr, 0,
+ (MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE));
+ memcpy(command_params[0].u.memref.shm->addr, sendbuf, send_size);
+
+ /* response */
+ command_params[1] = (struct tee_param) {
+ .attr = TEE_PARAM_ATTR_TYPE_MEMREF_INOUT,
+ .u.memref = {
+ .shm = shm,
+ .size = MAX_RESPONSE_SIZE,
+ .shm_offs = MAX_COMMAND_SIZE,
+ },
+ };
+
+ rc = tee_invoke_func(context->tee_dev, &transceive_args, 4,
+ command_params);
+ if ((rc < 0) || (transceive_args.ret != 0)) {
+ debug("%s:SUBMIT_COMMAND invoke error: 0x%x\n",
+ __func__, transceive_args.ret);
+ return (rc < 0) ? rc : transceive_args.ret;
+ }
+
+ resp_buf = command_params[1].u.memref.shm->addr +
+ command_params[1].u.memref.shm_offs;
+ resp_header = (struct tpm_output_header *)resp_buf;
+ resp_len = be32_to_cpu(resp_header->length);
+
+ /* sanity check resp_len*/
+ if (resp_len < TPM_HEADER_SIZE) {
+ debug("%s:tpm response header too small\n", __func__);
+ return -EIO;
+ }
+ if (resp_len > MAX_RESPONSE_SIZE) {
+ debug("%s:resp_len=%zd exceeds MAX_RESPONSE_SIZE\n",
+ __func__, resp_len);
+ return -EIO;
+ }
+ if (resp_len > *recv_len) {
+ debug("%s:response length is bigger than receive buffer\n",
+ __func__);
+ return -EIO;
+ }
+
+ /* sanity checks look good, copy the response */
+ memcpy(recvbuf, resp_buf, resp_len);
+ *recv_len = resp_len;
+
+ return 0;
+}
+
+static int ftpm_tee_open(struct udevice *dev)
+{
+ struct ftpm_tee_private *context = dev_get_priv(dev);
+
+ if (context->is_open)
+ return -EBUSY;
+
+ context->is_open = 1;
+
+ return 0;
+}
+
+static int ftpm_tee_close(struct udevice *dev)
+{
+ struct ftpm_tee_private *context = dev_get_priv(dev);
+
+ if (context->is_open)
+ context->is_open = 0;
+
+ return 0;
+}
+
+static int ftpm_tee_desc(struct udevice *dev, char *buf, int size)
+{
+ if (size < 32)
+ return -ENOSPC;
+
+ return snprintf(buf, size, "Microsoft OP-TEE fTPM");
+}
+
+static int ftpm_tee_match(struct tee_version_data *vers, const void *data)
+{
+ debug("%s:vers->gen_caps =0x%x\n", __func__, vers->gen_caps);
+
+ /*
+ * Currently this driver only support GP Complaint OPTEE based fTPM TA
+ */
+ return vers->gen_caps & TEE_GEN_CAP_GP;
+}
+
+static int ftpm_tee_probe(struct udevice *dev)
+{
+ int rc;
+ struct tpm_chip_priv *priv = dev_get_uclass_priv(dev);
+ struct ftpm_tee_private *context = dev_get_priv(dev);
+ struct tee_open_session_arg sess_arg;
+ const struct tee_optee_ta_uuid uuid = TA_FTPM_UUID;
+
+ memset(context, 0, sizeof(*context));
+
+ /* Use the TPM v2 stack */
+ priv->version = TPM_V2;
+ priv->pcr_count = 24;
+ priv->pcr_select_min = 3;
+
+ /* Find TEE device */
+ context->tee_dev = tee_find_device(NULL, ftpm_tee_match, NULL, NULL);
+ if (!context->tee_dev) {
+ debug("%s:tee_find_device failed\n", __func__);
+ return -ENODEV;
+ }
+
+ /* Open a session with the fTPM TA */
+ memset(&sess_arg, 0, sizeof(sess_arg));
+ tee_optee_ta_uuid_to_octets(sess_arg.uuid, &uuid);
+
+ rc = tee_open_session(context->tee_dev, &sess_arg, 0, NULL);
+ if ((rc < 0) || (sess_arg.ret != 0)) {
+ debug("%s:tee_open_session failed, err=%x\n",
+ __func__, sess_arg.ret);
+ return -EIO;
+ }
+ context->session = sess_arg.session;
+
+ /* Allocate dynamic shared memory with fTPM TA */
+ rc = tee_shm_alloc(context->tee_dev,
+ MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE,
+ 0, &context->shm);
+ if (rc) {
+ debug("%s:tee_shm_alloc failed with rc = %d\n", __func__, rc);
+ goto out_shm_alloc;
+ }
+
+ return 0;
+
+out_shm_alloc:
+ tee_close_session(context->tee_dev, context->session);
+
+ return rc;
+}
+
+static int ftpm_tee_remove(struct udevice *dev)
+{
+ struct ftpm_tee_private *context = dev_get_priv(dev);
+ int rc;
+
+ /* tee_pre_remove frees any leftover TEE shared memory */
+
+ /* close the existing session with fTPM TA*/
+ rc = tee_close_session(context->tee_dev, context->session);
+ debug("%s: tee_close_session - rc =%d\n", __func__, rc);
+
+ return 0;
+}
+
+static const struct tpm_ops ftpm_tee_ops = {
+ .open = ftpm_tee_open,
+ .close = ftpm_tee_close,
+ .get_desc = ftpm_tee_desc,
+ .xfer = ftpm_tee_transceive,
+};
+
+static const struct udevice_id ftpm_tee_ids[] = {
+ { .compatible = "microsoft,ftpm" },
+ { }
+};
+
+U_BOOT_DRIVER(ftpm_tee) = {
+ .name = "ftpm_tee",
+ .id = UCLASS_TPM,
+ .of_match = ftpm_tee_ids,
+ .ops = &ftpm_tee_ops,
+ .probe = ftpm_tee_probe,
+ .remove = ftpm_tee_remove,
+ .flags = DM_FLAG_OS_PREPARE,
+ .priv_auto_alloc_size = sizeof(struct ftpm_tee_private),
+};
diff --git a/drivers/tpm/tpm2_ftpm_tee.h b/drivers/tpm/tpm2_ftpm_tee.h
new file mode 100644
index 0000000000..44f9598c28
--- /dev/null
+++ b/drivers/tpm/tpm2_ftpm_tee.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) Microsoft Corporation
+ */
+
+#ifndef __TPM2_FTPM_TEE_H__
+#define __TPM2_FTPM_TEE_H__
+
+/* This UUID is generated with uuidgen */
+#define TA_FTPM_UUID { 0xBC50D971, 0xD4C9, 0x42C4, \
+ {0x82, 0xCB, 0x34, 0x3F, 0xB7, 0xF3, 0x78, 0x96} }
+
+/* The TAFs ID implemented in this TA */
+#define FTPM_OPTEE_TA_SUBMIT_COMMAND (0)
+#define FTPM_OPTEE_TA_EMULATE_PPI (1)
+
+/* max. buffer size supported by fTPM */
+#define MAX_COMMAND_SIZE 4096
+#define MAX_RESPONSE_SIZE 4096
+
+/**
+ * struct ftpm_tee_private - fTPM's private context
+ * @tee_dev: struct udevice for TEE.
+ * @session: fTPM TA session identifier.
+ * @is_open: Indicates whether the driver is already opened by client or not.
+ * @shm: Memory pool shared with fTPM TA in TEE.
+ */
+struct ftpm_tee_private {
+ struct udevice *tee_dev;
+ u32 session;
+ int is_open;
+ struct tee_shm *shm;
+};
+
+#endif /* __TPM2_FTPM_TEE_H__ */
--
2.24.1
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