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qemu-e2k/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 "qemu/osdep.h"
#include "qemu/error-report.h"
#include "tpm_util.h"
#include "tpm_int.h"
#include "exec/memory.h"
#define DEBUG_TPM 0
#define DPRINTF(fmt, ...) do { \
if (DEBUG_TPM) { \
fprintf(stderr, "tpm-util:"fmt"\n", ## __VA_ARGS__); \
} \
} while (0)
/*
* Write an error message in the given output buffer.
*/
void tpm_util_write_fatal_error_response(uint8_t *out, uint32_t out_len)
{
if (out_len >= sizeof(struct tpm_resp_hdr)) {
struct tpm_resp_hdr *resp = (struct tpm_resp_hdr *)out;
resp->tag = cpu_to_be16(TPM_TAG_RSP_COMMAND);
resp->len = cpu_to_be32(sizeof(struct tpm_resp_hdr));
resp->errcode = cpu_to_be32(TPM_FAIL);
}
}
bool tpm_util_is_selftest(const uint8_t *in, uint32_t in_len)
{
struct tpm_req_hdr *hdr = (struct tpm_req_hdr *)in;
if (in_len >= sizeof(*hdr)) {
return (be32_to_cpu(hdr->ordinal) == TPM_ORD_ContinueSelfTest);
}
return false;
}
/*
* Send request to a TPM device. We expect a response within one second.
*/
static int tpm_util_request(int fd,
unsigned char *request,
size_t requestlen,
unsigned char *response,
size_t responselen)
{
struct tpm_resp_hdr *resp;
fd_set readfds;
int n;
struct timeval tv = {
.tv_sec = 1,
.tv_usec = 0,
};
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, response, responselen);
if (n < sizeof(struct tpm_resp_hdr)) {
return -EFAULT;
}
resp = (struct tpm_resp_hdr *)response;
/* check the header */
if (be32_to_cpu(resp->len) != n) {
return -EMSGSIZE;
}
return 0;
}
/*
* A basic test of a TPM device. We expect a well formatted response header
* (error response is fine).
*/
static int tpm_util_test(int fd,
unsigned char *request,
size_t requestlen,
uint16_t *return_tag)
{
struct tpm_resp_hdr *resp;
unsigned char buf[1024];
ssize_t ret;
ret = tpm_util_request(fd, request, requestlen,
buf, sizeof(buf));
if (ret < 0) {
return ret;
}
resp = (struct tpm_resp_hdr *)buf;
*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;
}
int tpm_util_get_buffer_size(int tpm_fd, TPMVersion tpm_version,
size_t *buffersize)
{
unsigned char buf[1024];
int ret;
switch (tpm_version) {
case TPM_VERSION_1_2: {
const struct tpm_req_get_buffer_size {
struct tpm_req_hdr hdr;
uint32_t capability;
uint32_t len;
uint32_t subcap;
} QEMU_PACKED tpm_get_buffer_size = {
.hdr = {
.tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
.len = cpu_to_be32(sizeof(tpm_get_buffer_size)),
.ordinal = cpu_to_be32(TPM_ORD_GetCapability),
},
.capability = cpu_to_be32(TPM_CAP_PROPERTY),
.len = cpu_to_be32(sizeof(uint32_t)),
.subcap = cpu_to_be32(TPM_CAP_PROP_INPUT_BUFFER),
};
struct tpm_resp_get_buffer_size {
struct tpm_resp_hdr hdr;
uint32_t len;
uint32_t buffersize;
} QEMU_PACKED *tpm_resp = (struct tpm_resp_get_buffer_size *)buf;
ret = tpm_util_request(tpm_fd, (unsigned char *)&tpm_get_buffer_size,
sizeof(tpm_get_buffer_size), buf, sizeof(buf));
if (ret < 0) {
return ret;
}
if (be32_to_cpu(tpm_resp->hdr.len) != sizeof(*tpm_resp) ||
be32_to_cpu(tpm_resp->len) != sizeof(uint32_t)) {
DPRINTF("tpm_resp->hdr.len = %u, expected = %zu\n",
be32_to_cpu(tpm_resp->hdr.len), sizeof(*tpm_resp));
DPRINTF("tpm_resp->len = %u, expected = %zu\n",
be32_to_cpu(tpm_resp->len), sizeof(uint32_t));
error_report("tpm_util: Got unexpected response to "
"TPM_GetCapability; errcode: 0x%x",
be32_to_cpu(tpm_resp->hdr.errcode));
return -EFAULT;
}
*buffersize = be32_to_cpu(tpm_resp->buffersize);
break;
}
case TPM_VERSION_2_0: {
const struct tpm2_req_get_buffer_size {
struct tpm_req_hdr hdr;
uint32_t capability;
uint32_t property;
uint32_t count;
} QEMU_PACKED tpm2_get_buffer_size = {
.hdr = {
.tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
.len = cpu_to_be32(sizeof(tpm2_get_buffer_size)),
.ordinal = cpu_to_be32(TPM2_CC_GetCapability),
},
.capability = cpu_to_be32(TPM2_CAP_TPM_PROPERTIES),
.property = cpu_to_be32(TPM2_PT_MAX_COMMAND_SIZE),
.count = cpu_to_be32(2), /* also get TPM2_PT_MAX_RESPONSE_SIZE */
};
struct tpm2_resp_get_buffer_size {
struct tpm_resp_hdr hdr;
uint8_t more;
uint32_t capability;
uint32_t count;
uint32_t property1;
uint32_t value1;
uint32_t property2;
uint32_t value2;
} QEMU_PACKED *tpm2_resp = (struct tpm2_resp_get_buffer_size *)buf;
ret = tpm_util_request(tpm_fd, (unsigned char *)&tpm2_get_buffer_size,
sizeof(tpm2_get_buffer_size), buf, sizeof(buf));
if (ret < 0) {
return ret;
}
if (be32_to_cpu(tpm2_resp->hdr.len) != sizeof(*tpm2_resp) ||
be32_to_cpu(tpm2_resp->count) != 2) {
DPRINTF("tpm2_resp->hdr.len = %u, expected = %zu\n",
be32_to_cpu(tpm2_resp->hdr.len), sizeof(*tpm2_resp));
DPRINTF("tpm2_resp->len = %u, expected = %u\n",
be32_to_cpu(tpm2_resp->count), 2);
error_report("tpm_util: Got unexpected response to "
"TPM2_GetCapability; errcode: 0x%x",
be32_to_cpu(tpm2_resp->hdr.errcode));
return -EFAULT;
}
*buffersize = MAX(be32_to_cpu(tpm2_resp->value1),
be32_to_cpu(tpm2_resp->value2));
break;
}
case TPM_VERSION_UNSPEC:
return -EFAULT;
}
DPRINTF("buffersize of device: %zu\n", *buffersize);
return 0;
}
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