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-rw-r--r--qemu/hw/tpm/tpm_util.c126
1 files changed, 126 insertions, 0 deletions
diff --git a/qemu/hw/tpm/tpm_util.c b/qemu/hw/tpm/tpm_util.c
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+++ b/qemu/hw/tpm/tpm_util.c
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+/*
+ * TPM utility functions
+ *
+ * Copyright (c) 2010 - 2015 IBM Corporation
+ * Authors:
+ * Stefan Berger <stefanb@us.ibm.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>
+ */
+
+#include "tpm_util.h"
+#include "tpm_int.h"
+
+/*
+ * A basic test of a TPM device. We expect a well formatted response header
+ * (error response is fine) within one second.
+ */
+static int tpm_util_test(int fd,
+ unsigned char *request,
+ size_t requestlen,
+ uint16_t *return_tag)
+{
+ struct tpm_resp_hdr *resp;
+ fd_set readfds;
+ int n;
+ struct timeval tv = {
+ .tv_sec = 1,
+ .tv_usec = 0,
+ };
+ unsigned char buf[1024];
+
+ n = write(fd, request, requestlen);
+ if (n < 0) {
+ return errno;
+ }
+ if (n != requestlen) {
+ return EFAULT;
+ }
+
+ FD_ZERO(&readfds);
+ FD_SET(fd, &readfds);
+
+ /* wait for a second */
+ n = select(fd + 1, &readfds, NULL, NULL, &tv);
+ if (n != 1) {
+ return errno;
+ }
+
+ n = read(fd, &buf, sizeof(buf));
+ if (n < sizeof(struct tpm_resp_hdr)) {
+ return EFAULT;
+ }
+
+ resp = (struct tpm_resp_hdr *)buf;
+ /* check the header */
+ if (be32_to_cpu(resp->len) != n) {
+ return EBADMSG;
+ }
+
+ *return_tag = be16_to_cpu(resp->tag);
+
+ return 0;
+}
+
+/*
+ * Probe for the TPM device in the back
+ * Returns 0 on success with the version of the probed TPM set, 1 on failure.
+ */
+int tpm_util_test_tpmdev(int tpm_fd, TPMVersion *tpm_version)
+{
+ /*
+ * Sending a TPM1.2 command to a TPM2 should return a TPM1.2
+ * header (tag = 0xc4) and error code (TPM_BADTAG = 0x1e)
+ *
+ * Sending a TPM2 command to a TPM 2 will give a TPM 2 tag in the
+ * header.
+ * Sending a TPM2 command to a TPM 1.2 will give a TPM 1.2 tag
+ * in the header and an error code.
+ */
+ const struct tpm_req_hdr test_req = {
+ .tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
+ .len = cpu_to_be32(sizeof(test_req)),
+ .ordinal = cpu_to_be32(TPM_ORD_GetTicks),
+ };
+
+ const struct tpm_req_hdr test_req_tpm2 = {
+ .tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
+ .len = cpu_to_be32(sizeof(test_req_tpm2)),
+ .ordinal = cpu_to_be32(TPM2_CC_ReadClock),
+ };
+ uint16_t return_tag;
+ int ret;
+
+ /* Send TPM 2 command */
+ ret = tpm_util_test(tpm_fd, (unsigned char *)&test_req_tpm2,
+ sizeof(test_req_tpm2), &return_tag);
+ /* TPM 2 would respond with a tag of TPM2_ST_NO_SESSIONS */
+ if (!ret && return_tag == TPM2_ST_NO_SESSIONS) {
+ *tpm_version = TPM_VERSION_2_0;
+ return 0;
+ }
+
+ /* Send TPM 1.2 command */
+ ret = tpm_util_test(tpm_fd, (unsigned char *)&test_req,
+ sizeof(test_req), &return_tag);
+ if (!ret && return_tag == TPM_TAG_RSP_COMMAND) {
+ *tpm_version = TPM_VERSION_1_2;
+ /* this is a TPM 1.2 */
+ return 0;
+ }
+
+ *tpm_version = TPM_VERSION_UNSPEC;
+
+ return 1;
+}