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/*

 *  passthrough TPM driver

 *

 *  Copyright (c) 2010 - 2013 IBM Corporation

 *  Authors:

 *    Stefan Berger <stefanb@us.ibm.com>

 *

 *  Copyright (C) 2011 IAIK, Graz University of Technology

 *    Author: Andreas Niederl

 *

 * 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 <dirent.h>

#include "qemu-common.h"

#include "qapi/error.h"

#include "qemu/sockets.h"

#include "sysemu/tpm_backend.h"

#include "tpm_int.h"

#include "hw/hw.h"

#include "hw/i386/pc.h"

#include "sysemu/tpm_backend_int.h"

#include "tpm_tis.h"

/* #define DEBUG_TPM */

#ifdef DEBUG_TPM

#define DPRINTF(fmt, ...) \

    do { fprintf(stderr, fmt, ## __VA_ARGS__); } while (0)

#else

#define DPRINTF(fmt, ...) \

    do { } while (0)

#endif

#define TYPE_TPM_PASSTHROUGH "tpm-passthrough"

#define TPM_PASSTHROUGH(obj) \

    OBJECT_CHECK(TPMPassthruState, (obj), TYPE_TPM_PASSTHROUGH)

static const TPMDriverOps tpm_passthrough_driver;

/* data structures */

typedef struct TPMPassthruThreadParams {

    TPMState *tpm_state;

    TPMRecvDataCB *recv_data_callback;

    TPMBackend *tb;

} TPMPassthruThreadParams;

struct TPMPassthruState {

    TPMBackend parent;

    TPMBackendThread tbt;

    TPMPassthruThreadParams tpm_thread_params;

    char *tpm_dev;

    int tpm_fd;

    bool tpm_executing;

    bool tpm_op_canceled;

    int cancel_fd;

    bool had_startup_error;

};

typedef struct TPMPassthruState TPMPassthruState;

#define TPM_PASSTHROUGH_DEFAULT_DEVICE "/dev/tpm0"

/* functions */

static void tpm_passthrough_cancel_cmd(TPMBackend *tb);

static int tpm_passthrough_unix_write(int fd, const uint8_t *buf, uint32_t len)

{

    return send_all(fd, buf, len);

}

static int tpm_passthrough_unix_read(int fd, uint8_t *buf, uint32_t len)

{

    return recv_all(fd, buf, len, true);

}

static uint32_t tpm_passthrough_get_size_from_buffer(const uint8_t *buf)

{

    struct tpm_resp_hdr *resp = (struct tpm_resp_hdr *)buf;

    return be32_to_cpu(resp->len);

}

/*

 * Write an error message in the given output buffer.

 */

static void tpm_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);

    }

}

static int tpm_passthrough_unix_tx_bufs(TPMPassthruState *tpm_pt,

                                        const uint8_t *in, uint32_t in_len,

                                        uint8_t *out, uint32_t out_len)

{

    int ret;

    tpm_pt->tpm_op_canceled = false;

    tpm_pt->tpm_executing = true;

    ret = tpm_passthrough_unix_write(tpm_pt->tpm_fd, in, in_len);

    if (ret != in_len) {

        if (!tpm_pt->tpm_op_canceled ||

            (tpm_pt->tpm_op_canceled && errno != ECANCELED)) {

            error_report("tpm_passthrough: error while transmitting data "

                         "to TPM: %s (%i)\n",

                         strerror(errno), errno);

        }

        goto err_exit;

    }

    tpm_pt->tpm_executing = false;

    ret = tpm_passthrough_unix_read(tpm_pt->tpm_fd, out, out_len);

    if (ret < 0) {

        if (!tpm_pt->tpm_op_canceled ||

            (tpm_pt->tpm_op_canceled && errno != ECANCELED)) {

            error_report("tpm_passthrough: error while reading data from "

                         "TPM: %s (%i)\n",

                         strerror(errno), errno);

        }

    } else if (ret < sizeof(struct tpm_resp_hdr) ||

               tpm_passthrough_get_size_from_buffer(out) != ret) {

        ret = -1;

        error_report("tpm_passthrough: received invalid response "

                     "packet from TPM\n");

    }

err_exit:

    if (ret < 0) {

        tpm_write_fatal_error_response(out, out_len);

    }

    tpm_pt->tpm_executing = false;

    return ret;

}

static int tpm_passthrough_unix_transfer(TPMPassthruState *tpm_pt,

                                         const TPMLocality *locty_data)

{

    return tpm_passthrough_unix_tx_bufs(tpm_pt,

                                        locty_data->w_buffer.buffer,

                                        locty_data->w_offset,

                                        locty_data->r_buffer.buffer,

                                        locty_data->r_buffer.size);

}

static void tpm_passthrough_worker_thread(gpointer data,

                                          gpointer user_data)

{

    TPMPassthruThreadParams *thr_parms = user_data;

    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(thr_parms->tb);

    TPMBackendCmd cmd = (TPMBackendCmd)data;

    DPRINTF("tpm_passthrough: processing command type %d\n", cmd);

    switch (cmd) {

    case TPM_BACKEND_CMD_PROCESS_CMD:

        tpm_passthrough_unix_transfer(tpm_pt,

                                      thr_parms->tpm_state->locty_data);

        thr_parms->recv_data_callback(thr_parms->tpm_state,

                                      thr_parms->tpm_state->locty_number);

        break;

    case TPM_BACKEND_CMD_INIT:

    case TPM_BACKEND_CMD_END:

    case TPM_BACKEND_CMD_TPM_RESET:

        /* nothing to do */

        break;

    }

}

/*

 * Start the TPM (thread). If it had been started before, then terminate

 * and start it again.

 */

static int tpm_passthrough_startup_tpm(TPMBackend *tb)

{

    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);

    /* terminate a running TPM */

    tpm_backend_thread_end(&tpm_pt->tbt);

    tpm_backend_thread_create(&tpm_pt->tbt,

                              tpm_passthrough_worker_thread,

                              &tpm_pt->tpm_thread_params);

    return 0;

}

static void tpm_passthrough_reset(TPMBackend *tb)

{

    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);

    DPRINTF("tpm_passthrough: CALL TO TPM_RESET!\n");

    tpm_passthrough_cancel_cmd(tb);

    tpm_backend_thread_end(&tpm_pt->tbt);

    tpm_pt->had_startup_error = false;

}

static int tpm_passthrough_init(TPMBackend *tb, TPMState *s,

                                TPMRecvDataCB *recv_data_cb)

{

    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);

    tpm_pt->tpm_thread_params.tpm_state = s;

    tpm_pt->tpm_thread_params.recv_data_callback = recv_data_cb;

    tpm_pt->tpm_thread_params.tb = tb;

    return 0;

}

static bool tpm_passthrough_get_tpm_established_flag(TPMBackend *tb)

{

    return false;

}

static bool tpm_passthrough_get_startup_error(TPMBackend *tb)

{

    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);

    return tpm_pt->had_startup_error;

}

static size_t tpm_passthrough_realloc_buffer(TPMSizedBuffer *sb)

{

    size_t wanted_size = 4096; /* Linux tpm.c buffer size */

    if (sb->size != wanted_size) {

        sb->buffer = g_realloc(sb->buffer, wanted_size);

        sb->size = wanted_size;

    }

    return sb->size;

}

static void tpm_passthrough_deliver_request(TPMBackend *tb)

{

    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);

    tpm_backend_thread_deliver_request(&tpm_pt->tbt);

}

static void tpm_passthrough_cancel_cmd(TPMBackend *tb)

{

    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);

    int n;

    /*

     * As of Linux 3.7 the tpm_tis driver does not properly cancel

     * commands on all TPM manufacturers' TPMs.

     * Only cancel if we're busy so we don't cancel someone else's

     * command, e.g., a command executed on the host.

     */

    if (tpm_pt->tpm_executing) {

        if (tpm_pt->cancel_fd >= 0) {

            n = write(tpm_pt->cancel_fd, "-", 1);

            if (n != 1) {

                error_report("Canceling TPM command failed: %s\n",

                             strerror(errno));

            } else {

                tpm_pt->tpm_op_canceled = true;

            }

        } else {

            error_report("Cannot cancel TPM command due to missing "

                         "TPM sysfs cancel entry");

        }

    }

}

static const char *tpm_passthrough_create_desc(void)

{

    return "Passthrough TPM backend driver";

}

/*

 * 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;

}

/*

 * Unless path or file descriptor set has been provided by user,

 * determine the sysfs cancel file following kernel documentation

 * in Documentation/ABI/stable/sysfs-class-tpm.

 * From /dev/tpm0 create /sys/class/misc/tpm0/device/cancel

 */

static int tpm_passthrough_open_sysfs_cancel(TPMBackend *tb)

{

    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);

    int fd = -1;

    char *dev;

    char path[PATH_MAX];

    if (tb->cancel_path) {

        fd = qemu_open(tb->cancel_path, O_WRONLY);

        if (fd < 0) {

            error_report("Could not open TPM cancel path : %s",

                         strerror(errno));

        }

        return fd;

    }

    dev = strrchr(tpm_pt->tpm_dev, '/');

    if (dev) {

        dev++;

        if (snprintf(path, sizeof(path), "/sys/class/misc/%s/device/cancel",

                     dev) < sizeof(path)) {

            fd = qemu_open(path, O_WRONLY);

            if (fd >= 0) {

                tb->cancel_path = g_strdup(path);

            } else {

                error_report("tpm_passthrough: Could not open TPM cancel "

                             "path %s : %s", path, strerror(errno));

            }

        }

    } else {

       error_report("tpm_passthrough: Bad TPM device path %s",

                    tpm_pt->tpm_dev);

    }

    return fd;

}

static int tpm_passthrough_handle_device_opts(QemuOpts *opts, TPMBackend *tb)

{

    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);

    const char *value;

    value = qemu_opt_get(opts, "cancel-path");

    if (value) {

        tb->cancel_path = g_strdup(value);

    }

    value = qemu_opt_get(opts, "path");

    if (!value) {

        value = TPM_PASSTHROUGH_DEFAULT_DEVICE;

    }

    tpm_pt->tpm_dev = g_strdup(value);

    tb->path = g_strdup(tpm_pt->tpm_dev);

    tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);

    if (tpm_pt->tpm_fd < 0) {

        error_report("Cannot access TPM device using '%s': %s\n",

                     tpm_pt->tpm_dev, strerror(errno));

        goto err_free_parameters;

    }

    if (tpm_passthrough_test_tpmdev(tpm_pt->tpm_fd)) {

        error_report("'%s' is not a TPM device.\n",

                     tpm_pt->tpm_dev);

        goto err_close_tpmdev;

    }

    return 0;

 err_close_tpmdev:

    qemu_close(tpm_pt->tpm_fd);

    tpm_pt->tpm_fd = -1;

 err_free_parameters:

    g_free(tb->path);

    tb->path = NULL;

    g_free(tpm_pt->tpm_dev);

    tpm_pt->tpm_dev = NULL;

    return 1;

}

static TPMBackend *tpm_passthrough_create(QemuOpts *opts, const char *id)

{

    Object *obj = object_new(TYPE_TPM_PASSTHROUGH);

    TPMBackend *tb = TPM_BACKEND(obj);

    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);

    tb->id = g_strdup(id);

    /* let frontend set the fe_model to proper value */

    tb->fe_model = -1;

    tb->ops = &tpm_passthrough_driver;

    if (tpm_passthrough_handle_device_opts(opts, tb)) {

        goto err_exit;

    }

    tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tb);

    if (tpm_pt->cancel_fd < 0) {

        goto err_exit;

    }

    return tb;

err_exit:

    g_free(tb->id);

    return NULL;

}

static void tpm_passthrough_destroy(TPMBackend *tb)

{

    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);

    tpm_passthrough_cancel_cmd(tb);

    tpm_backend_thread_end(&tpm_pt->tbt);

    qemu_close(tpm_pt->tpm_fd);

    qemu_close(tpm_pt->cancel_fd);

    g_free(tb->id);

    g_free(tb->path);

    g_free(tb->cancel_path);

    g_free(tpm_pt->tpm_dev);

}

static const TPMDriverOps tpm_passthrough_driver = {

    .type                     = TPM_TYPE_PASSTHROUGH,

    .desc                     = tpm_passthrough_create_desc,

    .create                   = tpm_passthrough_create,

    .destroy                  = tpm_passthrough_destroy,

    .init                     = tpm_passthrough_init,

    .startup_tpm              = tpm_passthrough_startup_tpm,

    .realloc_buffer           = tpm_passthrough_realloc_buffer,

    .reset                    = tpm_passthrough_reset,

    .had_startup_error        = tpm_passthrough_get_startup_error,

    .deliver_request          = tpm_passthrough_deliver_request,

    .cancel_cmd               = tpm_passthrough_cancel_cmd,

    .get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag,

};

static void tpm_passthrough_inst_init(Object *obj)

{

}

static void tpm_passthrough_inst_finalize(Object *obj)

{

}

static void tpm_passthrough_class_init(ObjectClass *klass, void *data)

{

    TPMBackendClass *tbc = TPM_BACKEND_CLASS(klass);

    tbc->ops = &tpm_passthrough_driver;

}

static const TypeInfo tpm_passthrough_info = {

    .name = TYPE_TPM_PASSTHROUGH,

    .parent = TYPE_TPM_BACKEND,

    .instance_size = sizeof(TPMPassthruState),

    .class_init = tpm_passthrough_class_init,

    .instance_init = tpm_passthrough_inst_init,

    .instance_finalize = tpm_passthrough_inst_finalize,

};

static void tpm_passthrough_register(void)

{

    type_register_static(&tpm_passthrough_info);

    tpm_register_driver(&tpm_passthrough_driver);

}

type_init(tpm_passthrough_register)