diff options
Diffstat (limited to 'tpm/tpm_passthrough.c')
| -rw-r--r-- | tpm/tpm_passthrough.c | 530 |
1 files changed, 530 insertions, 0 deletions
diff --git a/tpm/tpm_passthrough.c b/tpm/tpm_passthrough.c new file mode 100644 index 0000000000..24aff4d69c --- /dev/null +++ b/tpm/tpm_passthrough.c @@ -0,0 +1,530 @@ +/* + * 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 "tpm_int.h" +#include "hw/hw.h" +#include "hw/pc.h" +#include "tpm_tis.h" +#include "tpm_backend.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 + +/* data structures */ + +typedef struct TPMPassthruThreadParams { + TPMState *tpm_state; + + TPMRecvDataCB *recv_data_callback; + TPMBackend *tb; +} TPMPassthruThreadParams; + +struct TPMPassthruState { + 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; +}; + +#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); +} + +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 = thr_parms->tb->s.tpm_pt; + 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 = tb->s.tpm_pt; + + /* terminate a running TPM */ + tpm_backend_thread_end(&tpm_pt->tbt); + + tpm_backend_thread_create(&tpm_pt->tbt, + tpm_passthrough_worker_thread, + &tb->s.tpm_pt->tpm_thread_params); + + return 0; +} + +static void tpm_passthrough_reset(TPMBackend *tb) +{ + TPMPassthruState *tpm_pt = tb->s.tpm_pt; + + 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 = tb->s.tpm_pt; + + 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 = tb->s.tpm_pt; + + 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 = tb->s.tpm_pt; + + tpm_backend_thread_deliver_request(&tpm_pt->tbt); +} + +static void tpm_passthrough_cancel_cmd(TPMBackend *tb) +{ + TPMPassthruState *tpm_pt = tb->s.tpm_pt; + 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; +} + +/* + * Check whether the given base path, e.g., /sys/class/misc/tpm0/device, + * is the sysfs directory of a TPM. A TPM sysfs directory should be uniquely + * recognizable by the file entries 'pcrs' and 'cancel'. + * Upon success 'true' is returned and the basebath buffer has '/cancel' + * appended. + */ +static bool tpm_passthrough_check_sysfs_cancel(char *basepath, size_t bufsz) +{ + char path[PATH_MAX]; + struct stat statbuf; + + snprintf(path, sizeof(path), "%s/pcrs", basepath); + if (stat(path, &statbuf) == -1 || !S_ISREG(statbuf.st_mode)) { + return false; + } + + snprintf(path, sizeof(path), "%s/cancel", basepath); + if (stat(path, &statbuf) == -1 || !S_ISREG(statbuf.st_mode)) { + return false; + } + + strncpy(basepath, path, bufsz); + + return true; +} + +/* + * 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. + */ +static int tpm_passthrough_open_sysfs_cancel(TPMBackend *tb) +{ + int fd = -1; + unsigned int idx; + DIR *pnp_dir; + char path[PATH_MAX]; + struct dirent entry, *result; + int len; + + 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; + } + + snprintf(path, sizeof(path), "/sys/class/misc"); + pnp_dir = opendir(path); + if (pnp_dir != NULL) { + while (readdir_r(pnp_dir, &entry, &result) == 0 && + result != NULL) { + /* + * only allow /sys/class/misc/tpm%u type of paths + */ + if (sscanf(entry.d_name, "tpm%u%n", &idx, &len) < 1 || + len <= strlen("tpm") || + len != strlen(entry.d_name)) { + continue; + } + + snprintf(path, sizeof(path), "/sys/class/misc/%s/device", + entry.d_name); + if (!tpm_passthrough_check_sysfs_cancel(path, sizeof(path))) { + continue; + } + + fd = qemu_open(path, O_WRONLY); + break; + } + closedir(pnp_dir); + } + + if (fd >= 0) { + tb->cancel_path = g_strdup(path); + } + + return fd; +} + +static int tpm_passthrough_handle_device_opts(QemuOpts *opts, TPMBackend *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; + } + + tb->s.tpm_pt->tpm_dev = g_strdup(value); + + tb->path = g_strdup(tb->s.tpm_pt->tpm_dev); + + tb->s.tpm_pt->tpm_fd = qemu_open(tb->s.tpm_pt->tpm_dev, O_RDWR); + if (tb->s.tpm_pt->tpm_fd < 0) { + error_report("Cannot access TPM device using '%s': %s\n", + tb->s.tpm_pt->tpm_dev, strerror(errno)); + goto err_free_parameters; + } + + if (tpm_passthrough_test_tpmdev(tb->s.tpm_pt->tpm_fd)) { + error_report("'%s' is not a TPM device.\n", + tb->s.tpm_pt->tpm_dev); + goto err_close_tpmdev; + } + + return 0; + + err_close_tpmdev: + qemu_close(tb->s.tpm_pt->tpm_fd); + tb->s.tpm_pt->tpm_fd = -1; + + err_free_parameters: + g_free(tb->path); + tb->path = NULL; + + g_free(tb->s.tpm_pt->tpm_dev); + tb->s.tpm_pt->tpm_dev = NULL; + + return 1; +} + +static TPMBackend *tpm_passthrough_create(QemuOpts *opts, const char *id) +{ + TPMBackend *tb; + + tb = g_new0(TPMBackend, 1); + tb->s.tpm_pt = g_new0(TPMPassthruState, 1); + 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; + } + + tb->s.tpm_pt->cancel_fd = tpm_passthrough_open_sysfs_cancel(tb); + if (tb->s.tpm_pt->cancel_fd < 0) { + goto err_exit; + } + + return tb; + +err_exit: + g_free(tb->id); + g_free(tb->s.tpm_pt); + g_free(tb); + + return NULL; +} + +static void tpm_passthrough_destroy(TPMBackend *tb) +{ + TPMPassthruState *tpm_pt = tb->s.tpm_pt; + + tpm_passthrough_cancel_cmd(tb); + + tpm_backend_thread_end(&tpm_pt->tbt); + + qemu_close(tpm_pt->tpm_fd); + qemu_close(tb->s.tpm_pt->cancel_fd); + + g_free(tb->id); + g_free(tb->path); + g_free(tb->cancel_path); + g_free(tb->s.tpm_pt->tpm_dev); + g_free(tb->s.tpm_pt); + g_free(tb); +} + +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_register(void) +{ + tpm_register_driver(&tpm_passthrough_driver); +} + +type_init(tpm_passthrough_register) |