Re: [tpmdd-devel] [PATCH v7 08/10] tpm: TPM 2.0 CRB Interface

[Jarkko Sakkinen]

On Wed, Nov 26, 2014 at 09:06:57AM -0500, Stefan Berger wrote:
> On 11/11/2014 08:45 AM, Jarkko Sakkinen wrote:
> >tpm_crb is a driver for TPM 2.0 Command Response Buffer (CRB) Interface
> >as defined in PC Client Platform TPM Profile (PTP) Specification.
> >
> >Only polling and single locality is supported as these are the limitations
> >of the available hardware, Platform Trust Techonlogy (PTT) in Haswell
> >CPUs.
> >
> >The driver always applies CRB with ACPI start because PTT reports using
> >only ACPI start as start method but as a result of my testing it requires
> >also CRB start.
> >
> >Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
> >---
> >  drivers/char/tpm/Kconfig   |   9 ++
> >  drivers/char/tpm/Makefile  |   1 +
> >  drivers/char/tpm/tpm_crb.c | 323 +++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 333 insertions(+)
> >  create mode 100644 drivers/char/tpm/tpm_crb.c
> >
> >diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
> >index c54cac3..10c9419 100644
> >--- a/drivers/char/tpm/Kconfig
> >+++ b/drivers/char/tpm/Kconfig
> >@@ -122,4 +122,13 @@ config TCG_XEN
> >  	  To compile this driver as a module, choose M here; the module
> >  	  will be called xen-tpmfront.
> >
> >+config TCG_CRB
> >+	tristate "TPM 2.0 CRB Interface"
> >+	depends on X86 && ACPI
> >+	---help---
> >+	  If you have a TPM security chip that is compliant with the
> >+	  TCG CRB 2.0 TPM specification say Yes and it will be accessible
> >+	  from within Linux.  To compile this driver as a module, choose
> >+	  M here; the module will be called tpm_crb.
> >+
> >  endif # TCG_TPM
> >diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
> >index ae56af9..e6d26dd 100644
> >--- a/drivers/char/tpm/Makefile
> >+++ b/drivers/char/tpm/Makefile
> >@@ -22,3 +22,4 @@ obj-$(CONFIG_TCG_INFINEON) += tpm_infineon.o
> >  obj-$(CONFIG_TCG_IBMVTPM) += tpm_ibmvtpm.o
> >  obj-$(CONFIG_TCG_ST33_I2C) += tpm_i2c_stm_st33.o
> >  obj-$(CONFIG_TCG_XEN) += xen-tpmfront.o
> >+obj-$(CONFIG_TCG_CRB) += tpm_crb.o
> >diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
> >new file mode 100644
> >index 0000000..eb221d5
> >--- /dev/null
> >+++ b/drivers/char/tpm/tpm_crb.c
> >@@ -0,0 +1,323 @@
> >+/*
> >+ * Copyright (C) 2014 Intel Corporation
> >+ *
> >+ * Authors:
> >+ * Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
> >+ *
> >+ * Maintained by: <tpmdd-devel@xxxxxxxxxxxxxxxxxxxxx>
> >+ *
> >+ * This device driver implements the TPM interface as defined in
> >+ * the TCG CRB 2.0 TPM specification.
> >+ *
> >+ * This program is free software; you can redistribute it and/or
> >+ * modify it under the terms of the GNU General Public License
> >+ * as published by the Free Software Foundation; version 2
> >+ * of the License.
> >+ */
> >+
> >+#include <linux/acpi.h>
> >+#include <linux/highmem.h>
> >+#include <linux/rculist.h>
> >+#include <linux/module.h>
> >+#include <linux/platform_device.h>
> >+#include "tpm.h"
> >+
> >+#define ACPI_SIG_TPM2 "TPM2"
> >+
> >+static const u8 CRB_ACPI_START_UUID[] = {
> >+	/* 0000 */ 0xAB, 0x6C, 0xBF, 0x6B, 0x63, 0x54, 0x14, 0x47,
> >+	/* 0008 */ 0xB7, 0xCD, 0xF0, 0x20, 0x3C, 0x03, 0x68, 0xD4
> >+};
> >+
> >+enum crb_defaults {
> >+	CRB_ACPI_START_REVISION_ID = 1,
> >+	CRB_ACPI_START_INDEX = 1,
> >+};
> >+
> >+enum crb_start_method {
> >+	CRB_SM_ACPI_START = 2,
> >+	CRB_SM_CRB = 7,
> >+	CRB_SM_CRB_WITH_ACPI_START = 8,
> >+};
> >+
> >+struct acpi_tpm2 {
> >+	struct acpi_table_header hdr;
> >+	u16 platform_class;
> >+	u16 reserved;
> >+	u64 control_area_pa;
> >+	u32 start_method;
> >+};
> >+
> >+enum crb_ca_request {
> >+	CRB_CA_REQ_GO_IDLE	= BIT(0),
> >+	CRB_CA_REQ_CMD_READY	= BIT(1),
> >+};
> >+
> >+enum crb_ca_status {
> >+	CRB_CA_STS_ERROR	= BIT(0),
> >+	CRB_CA_STS_TPM_IDLE	= BIT(1),
> >+};
> >+
> >+struct crb_control_area {
> >+	u32 req;
> >+	u32 sts;
> >+	u32 cancel;
> >+	u32 start;
> >+	u32 int_enable;
> >+	u32 int_sts;
> >+	u32 cmd_size;
> >+	u64 cmd_pa;
> >+	u32 rsp_size;
> >+	u64 rsp_pa;
> >+} __packed;
> >+
> >+enum crb_status {
> >+	CRB_STS_COMPLETE	= BIT(0),
> >+};
> >+
> >+enum crb_flags {
> >+	CRB_FL_ACPI_START	= BIT(0),
> >+	CRB_FL_CRB_START	= BIT(1),
> >+};
> >+
> >+struct crb_priv {
> >+	unsigned int flags;
> >+	struct crb_control_area *cca;
> >+	unsigned long cca_pa;
> >+};
> >+
> >+#ifdef CONFIG_PM_SLEEP
> >+int crb_suspend(struct device *dev)
> >+{
> >+	return 0;
> >+}
> >+
> >+static int crb_resume(struct device *dev)
> >+{
> >+	struct tpm_chip *chip = dev_get_drvdata(dev);
> >+
> >+	(void) tpm2_do_selftest(chip);
> >+
> >+	return 0;
> >+}
> >+#endif
> >+
> >+static SIMPLE_DEV_PM_OPS(crb_pm, crb_suspend, crb_resume);
> >+
> >+static u8 crb_status(struct tpm_chip *chip)
> >+{
> >+	struct crb_priv *priv = chip->vendor.priv;
> >+	u8 sts = 0;
> >+
> >+	if ((le32_to_cpu(priv->cca->start) & 1) != 1)
> 
> Use a #define rather than the magic '1'.
> 
> 
> >+		sts |= CRB_STS_COMPLETE;
> >+
> >+	return sts;
> >+}
> >+
> >+static int crb_recv(struct tpm_chip *chip, u8 *buf, size_t count)
> >+{
> >+	struct crb_priv *priv = chip->vendor.priv;
> >+	struct crb_control_area *cca;
> >+	unsigned int expected;
> >+	unsigned long offset;
> >+	u8 *resp;
> >+
> >+	cca = priv->cca;
> >+	if (le32_to_cpu(cca->sts) & CRB_CA_STS_ERROR)
> >+		return -EIO;
> >+
> >+	offset = le64_to_cpu(cca->rsp_pa) - priv->cca_pa;
> >+	resp = (u8 *) ((unsigned long) cca + offset);
> 
> make sure that count >= 6?
> 
> >+	memcpy(buf, resp, 6);
> >+	expected = be32_to_cpup((__be32 *) &buf[2]);
> >+
> >+	if (expected > count)
> >+		return -EIO;
> >+
> >+	memcpy(&buf[6], &resp[6], expected - 6);
> >+
> >+	return expected;
> >+}
> >+
> >+static int crb_do_acpi_start(struct tpm_chip *chip)
> >+{
> >+	union acpi_object *obj;
> >+	int rc;
> >+
> >+	obj = acpi_evaluate_dsm(chip->acpi_dev_handle,
> >+				CRB_ACPI_START_UUID,
> >+				CRB_ACPI_START_REVISION_ID,
> >+				CRB_ACPI_START_INDEX,
> >+				NULL);
> >+	if (!obj)
> >+		return -ENXIO;
> >+	rc = obj->integer.value == 0 ? 0 : -ENXIO;
> >+	ACPI_FREE(obj);
> >+	return rc;
> >+}
> >+
> >+static int crb_send(struct tpm_chip *chip, u8 *buf, size_t len)
> >+{
> >+	struct crb_priv *priv = chip->vendor.priv;
> >+	struct crb_control_area *cca;
> >+	u8 *cmd;
> >+	int rc = 0;
> >+
> >+	cca = priv->cca;
> >+
> >+	if (len > le32_to_cpu(cca->cmd_size)) {
> >+		dev_err(&chip->dev,
> >+			"invalid command count value %x %zx\n",
> >+			(unsigned int) len,
> >+			(size_t) le32_to_cpu(cca->cmd_size));
> >+		return -E2BIG;
> >+	}
> >+
> >+	cmd = (u8 *) ((unsigned long) cca + le64_to_cpu(cca->cmd_pa) -
> >+		      priv->cca_pa);
> 
> cca = priv->cca per statement above     -> cmd = cca + x - cca = x
> 
> -> cmd = le64_to_cpu(cca->cmd_pa);
> 
> Should do the trick, no ?
> 
> >+	memcpy(cmd, buf, len);
> >+
> >+	/* Make sure that cmd is populated before issuing start. */
> >+	wmb();
> >+
> >+	cca->start = cpu_to_le32(1);
> >+	rc = crb_do_acpi_start(chip);
> 
> I had commented on this already. Your TPM seems to no implement the ACPI
> specs properly, or rather the ACPI table is wrong.
> You have to check whether the ACPI function needs to be called. The next TPM
> from a different vendor for whom the ACPI start function is not necessary
> will need this check here since it will give a return code indicating
> failure. Then your TPM won't work anymore! I think you should add a check
> into the crb_do_acpi_start for whether this function needs to be called or
> whether your TPM is being used (vendor check?) and run this start function
> then anyway.

PTT (4th Core CRB implementation) seems to report needing ACPI start only but
in practice requires both. I fixed this now by flagging ACPI start with
CRB_FL_ACPI_START always doing cca->start assignment. I added comment to 
document this issue.

Maybe it would good idea to check for MSFT0101 and do assignment of 
CRB_FL_CRB_START if that holds? Then all the quirks would be in the
initialization code.

> >+	return rc;
> >+}
> >+
> >+static void crb_cancel(struct tpm_chip *chip)
> >+{
> >+	struct crb_priv *priv = chip->vendor.priv;
> >+	struct crb_control_area *cca;
> >+
> >+	cca = priv->cca;
> >+	cca->cancel = cpu_to_le32(1);
> 
> nit: #define for this ?
> 
> >+
> >+	/* Make sure that cmd is populated before issuing start. */
> >+	wmb();
> >+
> >+	if (crb_do_acpi_start(chip))
> >+		dev_err(&chip->dev, "ACPI Start failed\n");
> >+
> >+	cca->cancel = 0;
> >+}
> >+
> >+static bool crb_req_canceled(struct tpm_chip *chip, u8 status)
> >+{
> >+	struct crb_priv *priv = chip->vendor.priv;
> >+
> >+	return (le32_to_cpu(priv->cca->cancel) & 1) == 1;
> >+}
> >+
> >+static const struct tpm_class_ops tpm_crb = {
> >+	.status = crb_status,
> >+	.recv = crb_recv,
> >+	.send = crb_send,
> >+	.cancel = crb_cancel,
> >+	.req_canceled = crb_req_canceled,
> >+	.req_complete_mask = CRB_STS_COMPLETE,
> >+	.req_complete_val = CRB_STS_COMPLETE,
> >+};
> >+
> >+static int crb_acpi_add(struct acpi_device *device)
> >+{
> >+	struct tpm_chip *chip;
> >+	struct acpi_tpm2 *buf;
> >+	struct crb_priv *priv;
> >+	struct device *dev = &device->dev;
> >+	acpi_status status;
> >+	u32 sm;
> >+	int rc;
> >+
> >+	chip = tpmm_chip_alloc(dev, &tpm_crb);
> >+	if (IS_ERR(chip))
> >+		return PTR_ERR(chip);
> >+
> >+	chip->flags = TPM_CHIP_FLAG_TPM2;
> >+
> >+	status = acpi_get_table(ACPI_SIG_TPM2, 1,
> >+				(struct acpi_table_header **) &buf);
> >+	if (ACPI_FAILURE(status)) {
> >+		dev_err(dev, "failed to get TPM2 ACPI table\n");
> >+		return -ENODEV;
> >+	}
> >+
> >+	priv = (struct crb_priv *) devm_kzalloc(dev, sizeof(struct crb_priv),
> >+						GFP_KERNEL);
> >+	if (!priv) {
> >+		dev_err(dev, "failed to devm_kzalloc for private data\n");
> >+		return -ENOMEM;
> >+	}
> >+
> >+	sm = le32_to_cpu(buf->start_method);
> 
> I wonder whether you should check whether that ACPI table is big enough to
> allow you accessing its start_method.
> 
> if (buf->length < sizeof(struct acpi_tpm2) ) {
>     return -EXYZ;
> }
> 
> >+
> >+	if (sm == CRB_SM_CRB || sm == CRB_SM_CRB_WITH_ACPI_START)
> >+		priv->flags |= CRB_FL_CRB_START;
> 
> You set this flag but you don't seem to check it anywhere.
> 
> >+
> >+	if (sm == CRB_SM_ACPI_START || sm == CRB_SM_CRB_WITH_ACPI_START)
> >+		priv->flags |= CRB_FL_ACPI_START;
> 
> 
> You set this flag but you don't seem to check it anywhere.
> >+
> >+	priv->cca_pa = le32_to_cpu(buf->control_area_pa);
> >+	priv->cca = (struct crb_control_area *)
> >+		devm_ioremap_nocache(dev, buf->control_area_pa, 0x1000);
> >+	if (!priv->cca) {
> >+		dev_err(dev, "allocating memory failed\n");
> >+		return -ENOMEM;
> >+	}
> >+
> >+	chip->vendor.priv = priv;
> >+
> >+	/* Default timeouts and durations */
> >+	chip->vendor.timeout_a = usecs_to_jiffies(TPM2_TIMEOUT_A);
> >+	chip->vendor.timeout_b = usecs_to_jiffies(TPM2_TIMEOUT_B);
> >+	chip->vendor.timeout_c = usecs_to_jiffies(TPM2_TIMEOUT_C);
> >+	chip->vendor.timeout_d = usecs_to_jiffies(TPM2_TIMEOUT_D);
> >+	chip->vendor.duration[TPM_SHORT] =
> >+		usecs_to_jiffies(TPM2_DURATION_SHORT);
> >+	chip->vendor.duration[TPM_MEDIUM] =
> >+		usecs_to_jiffies(TPM2_DURATION_MEDIUM);
> >+	chip->vendor.duration[TPM_LONG] =
> >+		usecs_to_jiffies(TPM2_DURATION_LONG);
> >+
> >+	chip->acpi_dev_handle = device->handle;
> >+
> >+	rc = tpm2_do_selftest(chip);
> >+	if (rc)
> >+		return rc;
> >+
> >+	return tpm_chip_register(chip);
> >+}
> >+
> >+int crb_acpi_remove(struct acpi_device *device)
> >+{
> >+	struct device *dev = &device->dev;
> >+	struct tpm_chip *chip = dev_get_drvdata(dev);
> >+
> >+	tpm_chip_unregister(chip);
> >+	return 0;
> >+}
> >+
> >+static struct acpi_device_id crb_device_ids[] = {
> >+	{"MSFT0101", 0},
> >+	{"", 0},
> >+};
> >+MODULE_DEVICE_TABLE(acpi, crb_device_ids);
> >+
> >+static struct acpi_driver crb_acpi_driver = {
> >+	.name = "tpm_crb",
> >+	.ids = crb_device_ids,
> >+	.ops = {
> >+		.add = crb_acpi_add,
> >+		.remove = crb_acpi_remove,
> >+	},
> >+	.drv = {
> >+		.pm = &crb_pm,
> >+	},
> >+};
> >+
> >+module_acpi_driver(crb_acpi_driver);
> >+MODULE_AUTHOR("Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>");
> >+MODULE_DESCRIPTION("TPM2 Driver");
> >+MODULE_VERSION("0.1");
> >+MODULE_LICENSE("GPL");
> 
> Regards,
>     Stefan
> 

/Jarkko
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