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tpm-emulator: protect concurrent ctrl_chr access

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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 <marcandre.lureau@redhat.com>
Reviewed-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
This commit is contained in:
Marc-André Lureau 2017-11-06 19:39:22 +01:00 committed by Stefan Berger
parent 83e83c34b2
commit 17b1af773e
1 changed files with 28 additions and 16 deletions
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44
hw/tpm/tpm_emulator.c
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@ -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)