From 683c4b775355cc7acd301e8efe7d4c1c9acdafd8 Mon Sep 17 00:00:00 2001 From: Stefan Berger Date: Sun, 5 Nov 2017 19:31:43 -0500 Subject: [PATCH] tpm: tpm_passthrough: Fail startup if FE buffer size < BE buffer size MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If the requested buffer size of the frontend is smaller than the fixed buffer size of the host's TPM, fail the startup_tpm() interface function, which will make the device unusable. We fail it because the backend TPM could produce larger packets than what the frontend could pass to the OS. The current combination of TIS frontend and either passthrough or emulator backend will not lead to this case since the TIS can support any size of buffer. Signed-off-by: Stefan Berger Reviewed-by: Marc-André Lureau --- hw/tpm/tpm_passthrough.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/hw/tpm/tpm_passthrough.c b/hw/tpm/tpm_passthrough.c index 886af9e702..487aae2043 100644 --- a/hw/tpm/tpm_passthrough.c +++ b/hw/tpm/tpm_passthrough.c @@ -304,6 +304,20 @@ static TPMBackend *tpm_passthrough_create(QemuOpts *opts) return TPM_BACKEND(obj); } +static int tpm_passthrough_startup_tpm(TPMBackend *tb, size_t buffersize) +{ + TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb); + + if (buffersize && buffersize < tpm_pt->tpm_buffersize) { + error_report("Requested buffer size of %zu is smaller than host TPM's " + "fixed buffer size of %zu", + buffersize, tpm_pt->tpm_buffersize); + return -1; + } + + return 0; +} + static TpmTypeOptions *tpm_passthrough_get_tpm_options(TPMBackend *tb) { TpmTypeOptions *options = g_new0(TpmTypeOptions, 1); @@ -362,6 +376,7 @@ static void tpm_passthrough_class_init(ObjectClass *klass, void *data) tbc->opts = tpm_passthrough_cmdline_opts; tbc->desc = "Passthrough TPM backend driver"; tbc->create = tpm_passthrough_create; + tbc->startup_tpm = tpm_passthrough_startup_tpm; tbc->reset = tpm_passthrough_reset; tbc->cancel_cmd = tpm_passthrough_cancel_cmd; tbc->get_tpm_established_flag = tpm_passthrough_get_tpm_established_flag;