405 lines
12 KiB
C
405 lines
12 KiB
C
/*
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* passthrough TPM driver
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*
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* Copyright (c) 2010 - 2013 IBM Corporation
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* Authors:
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* Stefan Berger <stefanb@us.ibm.com>
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*
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* Copyright (C) 2011 IAIK, Graz University of Technology
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* Author: Andreas Niederl
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>
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*/
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#include "qemu/osdep.h"
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#include "qemu-common.h"
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#include "qemu/error-report.h"
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#include "qemu/module.h"
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#include "qemu/sockets.h"
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#include "sysemu/tpm_backend.h"
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#include "sysemu/tpm_util.h"
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#include "tpm_int.h"
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#include "qapi/clone-visitor.h"
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#include "qapi/qapi-visit-tpm.h"
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#include "trace.h"
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#define TYPE_TPM_PASSTHROUGH "tpm-passthrough"
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#define TPM_PASSTHROUGH(obj) \
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OBJECT_CHECK(TPMPassthruState, (obj), TYPE_TPM_PASSTHROUGH)
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/* data structures */
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struct TPMPassthruState {
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TPMBackend parent;
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TPMPassthroughOptions *options;
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const char *tpm_dev;
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int tpm_fd;
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bool tpm_executing;
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bool tpm_op_canceled;
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int cancel_fd;
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TPMVersion tpm_version;
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size_t tpm_buffersize;
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};
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typedef struct TPMPassthruState TPMPassthruState;
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#define TPM_PASSTHROUGH_DEFAULT_DEVICE "/dev/tpm0"
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/* functions */
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static void tpm_passthrough_cancel_cmd(TPMBackend *tb);
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static int tpm_passthrough_unix_read(int fd, uint8_t *buf, uint32_t len)
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{
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int ret;
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reread:
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ret = read(fd, buf, len);
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if (ret < 0) {
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if (errno != EINTR && errno != EAGAIN) {
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return -1;
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}
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goto reread;
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}
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return ret;
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}
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static void tpm_passthrough_unix_tx_bufs(TPMPassthruState *tpm_pt,
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const uint8_t *in, uint32_t in_len,
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uint8_t *out, uint32_t out_len,
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bool *selftest_done, Error **errp)
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{
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ssize_t ret;
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bool is_selftest;
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/* FIXME: protect shared variables or use other sync mechanism */
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tpm_pt->tpm_op_canceled = false;
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tpm_pt->tpm_executing = true;
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*selftest_done = false;
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is_selftest = tpm_util_is_selftest(in, in_len);
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ret = qemu_write_full(tpm_pt->tpm_fd, in, in_len);
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if (ret != in_len) {
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if (!tpm_pt->tpm_op_canceled || errno != ECANCELED) {
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error_setg_errno(errp, errno, "tpm_passthrough: error while "
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"transmitting data to TPM");
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}
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goto err_exit;
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}
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tpm_pt->tpm_executing = false;
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ret = tpm_passthrough_unix_read(tpm_pt->tpm_fd, out, out_len);
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if (ret < 0) {
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if (!tpm_pt->tpm_op_canceled || errno != ECANCELED) {
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error_setg_errno(errp, errno, "tpm_passthrough: error while "
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"reading data from TPM");
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}
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} else if (ret < sizeof(struct tpm_resp_hdr) ||
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tpm_cmd_get_size(out) != ret) {
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ret = -1;
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error_setg_errno(errp, errno, "tpm_passthrough: received invalid "
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"response packet from TPM");
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}
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if (is_selftest && (ret >= sizeof(struct tpm_resp_hdr))) {
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*selftest_done = tpm_cmd_get_errcode(out) == 0;
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}
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err_exit:
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if (ret < 0) {
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tpm_util_write_fatal_error_response(out, out_len);
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}
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tpm_pt->tpm_executing = false;
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}
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static void tpm_passthrough_handle_request(TPMBackend *tb, TPMBackendCmd *cmd,
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Error **errp)
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{
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TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
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trace_tpm_passthrough_handle_request(cmd);
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tpm_passthrough_unix_tx_bufs(tpm_pt, cmd->in, cmd->in_len,
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cmd->out, cmd->out_len, &cmd->selftest_done,
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errp);
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}
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static void tpm_passthrough_reset(TPMBackend *tb)
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{
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trace_tpm_passthrough_reset();
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tpm_passthrough_cancel_cmd(tb);
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}
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static bool tpm_passthrough_get_tpm_established_flag(TPMBackend *tb)
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{
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return false;
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}
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static int tpm_passthrough_reset_tpm_established_flag(TPMBackend *tb,
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uint8_t locty)
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{
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/* only a TPM 2.0 will support this */
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return 0;
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}
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static void tpm_passthrough_cancel_cmd(TPMBackend *tb)
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{
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TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
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int n;
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/*
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* As of Linux 3.7 the tpm_tis driver does not properly cancel
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* commands on all TPM manufacturers' TPMs.
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* Only cancel if we're busy so we don't cancel someone else's
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* command, e.g., a command executed on the host.
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*/
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if (tpm_pt->tpm_executing) {
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if (tpm_pt->cancel_fd >= 0) {
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tpm_pt->tpm_op_canceled = true;
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n = write(tpm_pt->cancel_fd, "-", 1);
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if (n != 1) {
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error_report("Canceling TPM command failed: %s",
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strerror(errno));
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}
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} else {
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error_report("Cannot cancel TPM command due to missing "
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"TPM sysfs cancel entry");
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}
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}
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}
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static TPMVersion tpm_passthrough_get_tpm_version(TPMBackend *tb)
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{
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TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
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return tpm_pt->tpm_version;
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}
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static size_t tpm_passthrough_get_buffer_size(TPMBackend *tb)
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{
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TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
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int ret;
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ret = tpm_util_get_buffer_size(tpm_pt->tpm_fd, tpm_pt->tpm_version,
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&tpm_pt->tpm_buffersize);
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if (ret < 0) {
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tpm_pt->tpm_buffersize = 4096;
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}
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return tpm_pt->tpm_buffersize;
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}
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/*
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* Unless path or file descriptor set has been provided by user,
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* determine the sysfs cancel file following kernel documentation
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* in Documentation/ABI/stable/sysfs-class-tpm.
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* From /dev/tpm0 create /sys/class/tpm/tpm0/device/cancel
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* before 4.0: /sys/class/misc/tpm0/device/cancel
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*/
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static int tpm_passthrough_open_sysfs_cancel(TPMPassthruState *tpm_pt)
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{
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int fd = -1;
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char *dev;
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char path[PATH_MAX];
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if (tpm_pt->options->cancel_path) {
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fd = qemu_open(tpm_pt->options->cancel_path, O_WRONLY);
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if (fd < 0) {
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error_report("tpm_passthrough: Could not open TPM cancel path: %s",
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strerror(errno));
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}
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return fd;
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}
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dev = strrchr(tpm_pt->tpm_dev, '/');
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if (!dev) {
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error_report("tpm_passthrough: Bad TPM device path %s",
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tpm_pt->tpm_dev);
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return -1;
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}
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dev++;
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if (snprintf(path, sizeof(path), "/sys/class/tpm/%s/device/cancel",
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dev) < sizeof(path)) {
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fd = qemu_open(path, O_WRONLY);
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if (fd < 0) {
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if (snprintf(path, sizeof(path), "/sys/class/misc/%s/device/cancel",
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dev) < sizeof(path)) {
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fd = qemu_open(path, O_WRONLY);
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}
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}
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}
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if (fd < 0) {
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error_report("tpm_passthrough: Could not guess TPM cancel path");
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} else {
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tpm_pt->options->cancel_path = g_strdup(path);
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}
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return fd;
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}
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static int
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tpm_passthrough_handle_device_opts(TPMPassthruState *tpm_pt, QemuOpts *opts)
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{
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const char *value;
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value = qemu_opt_get(opts, "cancel-path");
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if (value) {
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tpm_pt->options->cancel_path = g_strdup(value);
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tpm_pt->options->has_cancel_path = true;
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}
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value = qemu_opt_get(opts, "path");
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if (value) {
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tpm_pt->options->has_path = true;
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tpm_pt->options->path = g_strdup(value);
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}
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tpm_pt->tpm_dev = value ? value : TPM_PASSTHROUGH_DEFAULT_DEVICE;
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tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);
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if (tpm_pt->tpm_fd < 0) {
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error_report("Cannot access TPM device using '%s': %s",
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tpm_pt->tpm_dev, strerror(errno));
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return -1;
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}
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if (tpm_util_test_tpmdev(tpm_pt->tpm_fd, &tpm_pt->tpm_version)) {
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error_report("'%s' is not a TPM device.",
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tpm_pt->tpm_dev);
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return -1;
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}
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tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tpm_pt);
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if (tpm_pt->cancel_fd < 0) {
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return -1;
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}
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return 0;
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}
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static TPMBackend *tpm_passthrough_create(QemuOpts *opts)
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{
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Object *obj = object_new(TYPE_TPM_PASSTHROUGH);
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if (tpm_passthrough_handle_device_opts(TPM_PASSTHROUGH(obj), opts)) {
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object_unref(obj);
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return NULL;
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}
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return TPM_BACKEND(obj);
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}
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static int tpm_passthrough_startup_tpm(TPMBackend *tb, size_t buffersize)
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{
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TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
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if (buffersize && buffersize < tpm_pt->tpm_buffersize) {
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error_report("Requested buffer size of %zu is smaller than host TPM's "
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"fixed buffer size of %zu",
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buffersize, tpm_pt->tpm_buffersize);
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return -1;
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}
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return 0;
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}
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static TpmTypeOptions *tpm_passthrough_get_tpm_options(TPMBackend *tb)
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{
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TpmTypeOptions *options = g_new0(TpmTypeOptions, 1);
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options->type = TPM_TYPE_OPTIONS_KIND_PASSTHROUGH;
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options->u.passthrough.data = QAPI_CLONE(TPMPassthroughOptions,
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TPM_PASSTHROUGH(tb)->options);
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return options;
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}
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static const QemuOptDesc tpm_passthrough_cmdline_opts[] = {
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TPM_STANDARD_CMDLINE_OPTS,
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{
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.name = "cancel-path",
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.type = QEMU_OPT_STRING,
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.help = "Sysfs file entry for canceling TPM commands",
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},
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{
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.name = "path",
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.type = QEMU_OPT_STRING,
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.help = "Path to TPM device on the host",
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},
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{ /* end of list */ },
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};
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static void tpm_passthrough_inst_init(Object *obj)
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{
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TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);
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tpm_pt->options = g_new0(TPMPassthroughOptions, 1);
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tpm_pt->tpm_fd = -1;
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tpm_pt->cancel_fd = -1;
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}
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static void tpm_passthrough_inst_finalize(Object *obj)
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{
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TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(obj);
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tpm_passthrough_cancel_cmd(TPM_BACKEND(obj));
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if (tpm_pt->tpm_fd >= 0) {
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qemu_close(tpm_pt->tpm_fd);
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}
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if (tpm_pt->cancel_fd >= 0) {
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qemu_close(tpm_pt->cancel_fd);
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}
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qapi_free_TPMPassthroughOptions(tpm_pt->options);
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}
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static void tpm_passthrough_class_init(ObjectClass *klass, void *data)
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{
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TPMBackendClass *tbc = TPM_BACKEND_CLASS(klass);
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tbc->type = TPM_TYPE_PASSTHROUGH;
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tbc->opts = tpm_passthrough_cmdline_opts;
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tbc->desc = "Passthrough TPM backend driver";
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tbc->create = tpm_passthrough_create;
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tbc->startup_tpm = tpm_passthrough_startup_tpm;
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tbc->reset = tpm_passthrough_reset;
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tbc->cancel_cmd = tpm_passthrough_cancel_cmd;
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tbc->get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag;
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tbc->reset_tpm_established_flag =
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tpm_passthrough_reset_tpm_established_flag;
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tbc->get_tpm_version = tpm_passthrough_get_tpm_version;
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tbc->get_buffer_size = tpm_passthrough_get_buffer_size;
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tbc->get_tpm_options = tpm_passthrough_get_tpm_options;
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tbc->handle_request = tpm_passthrough_handle_request;
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}
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static const TypeInfo tpm_passthrough_info = {
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.name = TYPE_TPM_PASSTHROUGH,
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.parent = TYPE_TPM_BACKEND,
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.instance_size = sizeof(TPMPassthruState),
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.class_init = tpm_passthrough_class_init,
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.instance_init = tpm_passthrough_inst_init,
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.instance_finalize = tpm_passthrough_inst_finalize,
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};
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static void tpm_passthrough_register(void)
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{
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type_register_static(&tpm_passthrough_info);
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}
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type_init(tpm_passthrough_register)
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