linux-kernel - [PATCH v2 4/5] tpm: ppi: Possibly show command parameter if TPM PPI 1.3 is used

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Message-Id: <20190117174135.2117937-5-stefanb@linux.ibm.com>
Date:   Thu, 17 Jan 2019 12:41:34 -0500
From:   Stefan Berger <stefanb@...ux.ibm.com>
To:     linux-integrity@...r.kernel.org, jarkko.sakkinen@...ux.intel.com
Cc:     linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, Stefan Berger <stefanb@...ux.ibm.com>
Subject: [PATCH v2 4/5] tpm: ppi: Possibly show command parameter if TPM PPI 1.3 is used

TPM PPI 1.3 introduces an additional optional command parameter
that may be needed for some commands. Display the parameter if the
command requires such a parameter. Only command 23 needs one.

The PPI request file will show output like this then:

   # echo "23 16" > request
   # cat request
   23 16

   # echo "5" > request
   # cat request
   5

Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
Tested-by: David Safford <david.safford@...com>
---
 drivers/char/tpm/tpm_ppi.c | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/drivers/char/tpm/tpm_ppi.c b/drivers/char/tpm/tpm_ppi.c
index fdfd6271351e..942a2f79e9da 100644
--- a/drivers/char/tpm/tpm_ppi.c
+++ b/drivers/char/tpm/tpm_ppi.c
@@ -21,6 +21,7 @@
 #include "tpm.h"
 
 #define TPM_PPI_REVISION_ID_1	1
+#define TPM_PPI_REVISION_ID_2	2
 #define TPM_PPI_FN_VERSION	1
 #define TPM_PPI_FN_SUBREQ	2
 #define TPM_PPI_FN_GETREQ	3
@@ -36,6 +37,11 @@ static const guid_t tpm_ppi_guid =
 	GUID_INIT(0x3DDDFAA6, 0x361B, 0x4EB4,
 		  0xA4, 0x24, 0x8D, 0x10, 0x08, 0x9D, 0x16, 0x53);
 
+static bool tpm_ppi_req_has_parameter(u64 req)
+{
+	return req == 23;
+}
+
 static inline union acpi_object *
 tpm_eval_dsm(acpi_handle ppi_handle, int func, acpi_object_type type,
 	     union acpi_object *argv4, u64 rev)
@@ -59,9 +65,14 @@ static ssize_t tpm_show_ppi_request(struct device *dev,
 	ssize_t size = -EINVAL;
 	union acpi_object *obj;
 	struct tpm_chip *chip = to_tpm_chip(dev);
+	u64 rev = TPM_PPI_REVISION_ID_2;
+	u64 req;
+
+	if (strcmp(chip->ppi_version, "1.2") < 0)
+		rev = TPM_PPI_REVISION_ID_1;
 
 	obj = tpm_eval_dsm(chip->acpi_dev_handle, TPM_PPI_FN_GETREQ,
-			   ACPI_TYPE_PACKAGE, NULL, TPM_PPI_REVISION_ID_1);
+			   ACPI_TYPE_PACKAGE, NULL, rev);
 	if (!obj)
 		return -ENXIO;
 
@@ -71,7 +82,23 @@ static ssize_t tpm_show_ppi_request(struct device *dev,
 	 * error. The second is pending TPM operation requested by the OS, 0
 	 * means none and >0 means operation value.
 	 */
-	if (obj->package.count == 2 &&
+	if (obj->package.count == 3 &&
+	    obj->package.elements[0].type == ACPI_TYPE_INTEGER &&
+	    obj->package.elements[1].type == ACPI_TYPE_INTEGER &&
+	    obj->package.elements[2].type == ACPI_TYPE_INTEGER) {
+		if (obj->package.elements[0].integer.value)
+			size = -EFAULT;
+		else {
+			req = obj->package.elements[1].integer.value;
+			if (tpm_ppi_req_has_parameter(req))
+				size = scnprintf(buf, PAGE_SIZE,
+				    "%llu %llu\n", req,
+				    obj->package.elements[2].integer.value);
+			else
+				size = scnprintf(buf, PAGE_SIZE,
+						"%llu\n", req);
+		}
+	} else if (obj->package.count == 2 &&
 	    obj->package.elements[0].type == ACPI_TYPE_INTEGER &&
 	    obj->package.elements[1].type == ACPI_TYPE_INTEGER) {
 		if (obj->package.elements[0].integer.value)
-- 
2.13.6