From 17b1af773ed81a9167abfa09749ab92bd05740b0 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= Date: Mon, 6 Nov 2017 19:39:22 +0100 Subject: [PATCH] tpm-emulator: protect concurrent ctrl_chr access MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The control chardev is being used from the data thread to set the locality of the next request. Altough the chr has a write mutex, we may potentially read the reply from another thread request. Add a mutex to protect from concurrent control commands. Signed-off-by: Marc-André Lureau Reviewed-by: Stefan Berger Signed-off-by: Stefan Berger --- hw/tpm/tpm_emulator.c | 44 +++++++++++++++++++++++++++---------------- 1 file changed, 28 insertions(+), 16 deletions(-) diff --git a/hw/tpm/tpm_emulator.c b/hw/tpm/tpm_emulator.c index 9aaec8e3ef..e1a68104d6 100644 --- a/hw/tpm/tpm_emulator.c +++ b/hw/tpm/tpm_emulator.c @@ -71,15 +71,21 @@ typedef struct TPMEmulator { ptm_cap caps; /* capabilities of the TPM */ uint8_t cur_locty_number; /* last set locality */ Error *migration_blocker; + + QemuMutex mutex; } TPMEmulator; -static int tpm_emulator_ctrlcmd(CharBackend *dev, unsigned long cmd, void *msg, +static int tpm_emulator_ctrlcmd(TPMEmulator *tpm, unsigned long cmd, void *msg, size_t msg_len_in, size_t msg_len_out) { + CharBackend *dev = &tpm->ctrl_chr; uint32_t cmd_no = cpu_to_be32(cmd); ssize_t n = sizeof(uint32_t) + msg_len_in; uint8_t *buf = NULL; + int ret = -1; + + qemu_mutex_lock(&tpm->mutex); buf = g_alloca(n); memcpy(buf, &cmd_no, sizeof(cmd_no)); @@ -87,17 +93,21 @@ static int tpm_emulator_ctrlcmd(CharBackend *dev, unsigned long cmd, void *msg, n = qemu_chr_fe_write_all(dev, buf, n); if (n <= 0) { - return -1; + goto end; } if (msg_len_out != 0) { n = qemu_chr_fe_read_all(dev, msg, msg_len_out); if (n <= 0) { - return -1; + goto end; } } - return 0; + ret = 0; + +end: + qemu_mutex_unlock(&tpm->mutex); + return ret; } static int tpm_emulator_unix_tx_bufs(TPMEmulator *tpm_emu, @@ -154,7 +164,7 @@ static int tpm_emulator_set_locality(TPMEmulator *tpm_emu, uint8_t locty_number, DPRINTF("setting locality : 0x%x", locty_number); loc.u.req.loc = locty_number; - if (tpm_emulator_ctrlcmd(&tpm_emu->ctrl_chr, CMD_SET_LOCALITY, &loc, + if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SET_LOCALITY, &loc, sizeof(loc), sizeof(loc)) < 0) { error_setg(errp, "tpm-emulator: could not set locality : %s", strerror(errno)); @@ -202,8 +212,8 @@ error: static int tpm_emulator_probe_caps(TPMEmulator *tpm_emu) { DPRINTF("%s", __func__); - if (tpm_emulator_ctrlcmd(&tpm_emu->ctrl_chr, CMD_GET_CAPABILITY, - &tpm_emu->caps, 0, sizeof(tpm_emu->caps)) < 0) { + if (tpm_emulator_ctrlcmd(tpm_emu, CMD_GET_CAPABILITY, + &tpm_emu->caps, 0, sizeof(tpm_emu->caps)) < 0) { error_report("tpm-emulator: probing failed : %s", strerror(errno)); return -1; } @@ -254,8 +264,8 @@ static int tpm_emulator_startup_tpm(TPMBackend *tb) ptm_res res; DPRINTF("%s", __func__); - if (tpm_emulator_ctrlcmd(&tpm_emu->ctrl_chr, CMD_INIT, &init, sizeof(init), - sizeof(init)) < 0) { + if (tpm_emulator_ctrlcmd(tpm_emu, CMD_INIT, &init, sizeof(init), + sizeof(init)) < 0) { error_report("tpm-emulator: could not send INIT: %s", strerror(errno)); goto err_exit; @@ -278,7 +288,7 @@ static bool tpm_emulator_get_tpm_established_flag(TPMBackend *tb) ptm_est est; DPRINTF("%s", __func__); - if (tpm_emulator_ctrlcmd(&tpm_emu->ctrl_chr, CMD_GET_TPMESTABLISHED, &est, + if (tpm_emulator_ctrlcmd(tpm_emu, CMD_GET_TPMESTABLISHED, &est, 0, sizeof(est)) < 0) { error_report("tpm-emulator: Could not get the TPM established flag: %s", strerror(errno)); @@ -302,7 +312,7 @@ static int tpm_emulator_reset_tpm_established_flag(TPMBackend *tb, } reset_est.u.req.loc = tpm_emu->cur_locty_number; - if (tpm_emulator_ctrlcmd(&tpm_emu->ctrl_chr, CMD_RESET_TPMESTABLISHED, + if (tpm_emulator_ctrlcmd(tpm_emu, CMD_RESET_TPMESTABLISHED, &reset_est, sizeof(reset_est), sizeof(reset_est)) < 0) { error_report("tpm-emulator: Could not reset the establishment bit: %s", @@ -330,7 +340,7 @@ static void tpm_emulator_cancel_cmd(TPMBackend *tb) return; } - if (tpm_emulator_ctrlcmd(&tpm_emu->ctrl_chr, CMD_CANCEL_TPM_CMD, &res, 0, + if (tpm_emulator_ctrlcmd(tpm_emu, CMD_CANCEL_TPM_CMD, &res, 0, sizeof(res)) < 0) { error_report("tpm-emulator: Could not cancel command: %s", strerror(errno)); @@ -378,8 +388,8 @@ static int tpm_emulator_prepare_data_fd(TPMEmulator *tpm_emu) qemu_chr_fe_set_msgfds(&tpm_emu->ctrl_chr, fds + 1, 1); - if (tpm_emulator_ctrlcmd(&tpm_emu->ctrl_chr, CMD_SET_DATAFD, &res, 0, - sizeof(res)) || res != 0) { + if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SET_DATAFD, &res, 0, + sizeof(res)) < 0 || res != 0) { error_report("tpm-emulator: Failed to send CMD_SET_DATAFD: %s", strerror(errno)); goto err_exit; @@ -501,6 +511,7 @@ static void tpm_emulator_inst_init(Object *obj) DPRINTF("%s", __func__); tpm_emu->options = g_new0(TPMEmulatorOptions, 1); tpm_emu->cur_locty_number = ~0; + qemu_mutex_init(&tpm_emu->mutex); } /* @@ -510,8 +521,7 @@ static void tpm_emulator_shutdown(TPMEmulator *tpm_emu) { ptm_res res; - if (tpm_emulator_ctrlcmd(&tpm_emu->ctrl_chr, CMD_SHUTDOWN, &res, 0, - sizeof(res)) < 0) { + if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SHUTDOWN, &res, 0, sizeof(res)) < 0) { error_report("tpm-emulator: Could not cleanly shutdown the TPM: %s", strerror(errno)); } else if (res != 0) { @@ -536,6 +546,8 @@ static void tpm_emulator_inst_finalize(Object *obj) migrate_del_blocker(tpm_emu->migration_blocker); error_free(tpm_emu->migration_blocker); } + + qemu_mutex_destroy(&tpm_emu->mutex); } static void tpm_emulator_class_init(ObjectClass *klass, void *data)