86 lines
2.9 KiB
Diff
86 lines
2.9 KiB
Diff
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From 98599df9392a346216c5a059b8d35271286100bb Mon Sep 17 00:00:00 2001
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From: Juergen Repp <juergen_repp@web.de>
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Date: Thu, 2 May 2024 09:10:01 +0800
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Subject: [PATCH] tpm2_checkquote: Add comparison of pcr selection.
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The pcr selection which is passed with the --pcr parameter it not
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compared with the attest. So it's possible to fake a valid
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attestation.
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Fixes: CVE-2024-29039
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Signed-off-by: Juergen Repp <juergen_repp@web.de>
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Signed-off-by: Andreas Fuchs <andreas.fuchs@infineon.com>
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---
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tools/misc/tpm2_checkquote.c | 41 +++++++++++++++++++++++++++++++++++-
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1 file changed, 40 insertions(+), 1 deletion(-)
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diff --git a/tools/misc/tpm2_checkquote.c b/tools/misc/tpm2_checkquote.c
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index b3947e7..81de000 100644
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--- a/tools/misc/tpm2_checkquote.c
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+++ b/tools/misc/tpm2_checkquote.c
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@@ -54,6 +54,37 @@ static tpm2_verifysig_ctx ctx = {
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.pcr_hash = TPM2B_TYPE_INIT(TPM2B_DIGEST, buffer),
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};
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+static bool compare_pcr_selection(TPML_PCR_SELECTION *attest_sel, TPML_PCR_SELECTION *pcr_sel) {
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+ if (attest_sel->count != pcr_sel->count) {
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+ LOG_ERR("Selection sizes do not match.");
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+ return false;
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+ }
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+ for (uint32_t i = 0; i < attest_sel->count; i++) {
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+ for (uint32_t j = 0; j < pcr_sel->count; j++) {
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+ if (attest_sel->pcrSelections[i].hash ==
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+ pcr_sel->pcrSelections[j].hash) {
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+ if (attest_sel->pcrSelections[i].sizeofSelect !=
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+ pcr_sel->pcrSelections[j].sizeofSelect) {
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+ LOG_ERR("Bitmask size does not match");
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+ return false;
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+ }
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+ if (memcmp(&attest_sel->pcrSelections[i].pcrSelect[0],
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+ &pcr_sel->pcrSelections[j].pcrSelect[0],
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+ attest_sel->pcrSelections[i].sizeofSelect) != 0) {
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+ LOG_ERR("Selection bitmasks do not match");
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+ return false;
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+ }
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+ break;
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+ }
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+ if (j == pcr_sel->count - 1) {
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+ LOG_ERR("Hash selections to not match.");
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+ return false;
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+ }
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+ }
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+ }
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+ return true;
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+}
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+
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static bool verify(void) {
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bool result = false;
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@@ -394,7 +425,7 @@ static tool_rc init(void) {
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}
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TPM2B_ATTEST *msg = NULL;
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- TPML_PCR_SELECTION pcr_select;
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+ TPML_PCR_SELECTION pcr_select = { 0 };
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tpm2_pcrs *pcrs;
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tpm2_pcrs temp_pcrs = {};
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tool_rc return_value = tool_rc_general_error;
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@@ -557,6 +588,14 @@ static tool_rc init(void) {
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goto err;
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}
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+ if (ctx.flags.pcr) {
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+ if (!compare_pcr_selection(&ctx.attest.attested.quote.pcrSelect,
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+ &pcr_select)) {
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+ LOG_ERR("PCR selection does not match PCR slection from attest!");
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+ goto err;
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+ }
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+ }
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+
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// Figure out the digest for this message
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res = tpm2_openssl_hash_compute_data(ctx.halg, msg->attestationData,
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msg->size, &ctx.msg_hash);
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--
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2.23.0
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