tpm: Probe for connected TPM 1.2 or TPM 2

In the TPM passthrough backend driver, modify the probing code so
that we can check whether a TPM 1.2 or TPM 2 is being used
and adapt the behavior of the TPM TIS accordingly.

Move the code that tested for a TPM 1.2 into tpm_utils.c
and extend it with test for probing for TPM 2. Have the
function return the version of TPM found.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/tpm/Makefile.objs

@@ -1,2 +1,2 @@
 common-obj-$(CONFIG_TPM_TIS) += tpm_tis.o
-common-obj-$(CONFIG_TPM_PASSTHROUGH) += tpm_passthrough.o
+common-obj-$(CONFIG_TPM_PASSTHROUGH) += tpm_passthrough.o tpm_util.o

hw/tpm/tpm_int.h

@@ -66,4 +66,10 @@ struct tpm_resp_hdr {
 #define TPM_ORD_ContinueSelfTest  0x53
 #define TPM_ORD_GetTicks          0xf1
 
+
+/* TPM2 defines */
+#define TPM2_ST_NO_SESSIONS       0x8001
+
+#define TPM2_CC_ReadClock         0x00000181
+
 #endif /* TPM_TPM_INT_H */

hw/tpm/tpm_passthrough.c

@@ -33,6 +33,7 @@
 #include "hw/i386/pc.h"
 #include "sysemu/tpm_backend_int.h"
 #include "tpm_tis.h"
+#include "tpm_util.h"
 
 #define DEBUG_TPM 0
 
@@ -69,6 +70,8 @@ struct TPMPassthruState {
     bool tpm_op_canceled;
     int cancel_fd;
     bool had_startup_error;
+
+    TPMVersion tpm_version;
 };
 
 typedef struct TPMPassthruState TPMPassthruState;
@@ -333,59 +336,9 @@ static const char *tpm_passthrough_create_desc(void)
 
 static TPMVersion tpm_passthrough_get_tpm_version(TPMBackend *tb)
 {
-    return TPM_VERSION_1_2;
-}
+    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
 
-/*
- * A basic test of a TPM device. We expect a well formatted response header
- * (error response is fine) within one second.
- */
-static int tpm_passthrough_test_tpmdev(int fd)
-{
-    struct tpm_req_hdr req = {
-        .tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
-        .len = cpu_to_be32(sizeof(req)),
-        .ordinal = cpu_to_be32(TPM_ORD_GetTicks),
-    };
-    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, &req, sizeof(req));
-    if (n < 0) {
-        return errno;
-    }
-    if (n != sizeof(req)) {
-        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 (be16_to_cpu(resp->tag) != TPM_TAG_RSP_COMMAND ||
-        be32_to_cpu(resp->len) != n) {
-        return EBADMSG;
-    }
-
-    return 0;
+    return tpm_pt->tpm_version;
 }
 
 /*
@@ -455,7 +408,7 @@ static int tpm_passthrough_handle_device_opts(QemuOpts *opts, TPMBackend *tb)
         goto err_free_parameters;
     }
 
-    if (tpm_passthrough_test_tpmdev(tpm_pt->tpm_fd)) {
+    if (tpm_util_test_tpmdev(tpm_pt->tpm_fd, &tpm_pt->tpm_version)) {
         error_report("'%s' is not a TPM device.",
                      tpm_pt->tpm_dev);
         goto err_close_tpmdev;

hw/tpm/tpm_util.c

@@ -0,0 +1,126 @@
+/*
+ * 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;
+}

hw/tpm/tpm_util.h

@@ -0,0 +1,28 @@
+/*
+ * 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/>
+ */
+#ifndef TPM_TPM_UTILS_H
+#define TPM_TPM_UTILS_H
+
+#include "sysemu/tpm_backend.h"
+
+int tpm_util_test_tpmdev(int tpm_fd, TPMVersion *tpm_version);
+
+#endif /* TPM_TPM_UTILS_H */