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149 lines
8.1 KiB
149 lines
8.1 KiB
8 months ago
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From 4555de31d96745cabd1362aea7ba3b849429e98b Mon Sep 17 00:00:00 2001
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From: Dan Streetman <ddstreet@ieee.org>
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Date: Fri, 5 May 2023 19:48:14 -0400
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Subject: [PATCH] boot/measure: replace TPM PolicyPCR session with calculation
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Instead of using a trial policy with a TPM to calculate the measurement hash,
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this uses a function to calculate the hash with no TPM needed.
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(cherry picked from commit b2efe286587e11e2aa4a6c7e4a2c15da3bb58a2a)
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Related: RHEL-16182
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---
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src/boot/measure.c | 85 +++++++++-------------------------------------
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1 file changed, 16 insertions(+), 69 deletions(-)
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diff --git a/src/boot/measure.c b/src/boot/measure.c
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index 86edf77c52..5ce3049147 100644
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--- a/src/boot/measure.c
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+++ b/src/boot/measure.c
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@@ -718,7 +718,6 @@ static int verb_sign(int argc, char *argv[], void *userdata) {
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_cleanup_(pcr_state_free_all) PcrState *pcr_states = NULL;
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_cleanup_(EVP_PKEY_freep) EVP_PKEY *privkey = NULL, *pubkey = NULL;
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_cleanup_fclose_ FILE *privkeyf = NULL;
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- TSS2_RC rc;
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size_t n;
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int r;
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@@ -787,15 +786,6 @@ static int verb_sign(int argc, char *argv[], void *userdata) {
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if (r < 0)
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return r;
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- r = dlopen_tpm2();
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- if (r < 0)
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- return r;
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-
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- _cleanup_tpm2_context_ Tpm2Context *c = NULL;
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- r = tpm2_context_new(arg_tpm2_device, &c);
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- if (r < 0)
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- return r;
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-
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STRV_FOREACH(phase, arg_phase) {
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r = measure_phase(pcr_states, n, *phase);
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@@ -803,42 +793,8 @@ static int verb_sign(int argc, char *argv[], void *userdata) {
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return r;
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for (size_t i = 0; i < n; i++) {
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- static const TPMT_SYM_DEF symmetric = {
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- .algorithm = TPM2_ALG_AES,
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- .keyBits.aes = 128,
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- .mode.aes = TPM2_ALG_CFB,
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- };
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PcrState *p = pcr_states + i;
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- _cleanup_tpm2_handle_ Tpm2Handle *session = NULL;
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- r = tpm2_handle_new(c, &session);
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- if (r < 0)
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- return r;
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-
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- rc = sym_Esys_StartAuthSession(
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- c->esys_context,
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- ESYS_TR_NONE,
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- ESYS_TR_NONE,
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- ESYS_TR_NONE,
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- ESYS_TR_NONE,
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- ESYS_TR_NONE,
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- NULL,
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- TPM2_SE_TRIAL,
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- &symmetric,
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- TPM2_ALG_SHA256,
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- &session->esys_handle);
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- if (rc != TSS2_RC_SUCCESS)
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- return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE),
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- "Failed to open session in TPM: %s", sym_Tss2_RC_Decode(rc));
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-
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- /* Generate a single hash value from the PCRs included in our policy. Given that that's
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- * exactly one, the calculation is trivial. */
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- TPM2B_DIGEST intermediate_digest = {
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- .size = SHA256_DIGEST_SIZE,
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- };
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- assert(sizeof(intermediate_digest.buffer) >= SHA256_DIGEST_SIZE);
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- sha256_direct(p->value, p->value_size, intermediate_digest.buffer);
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-
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int tpmalg = tpm2_hash_alg_from_string(EVP_MD_name(p->md));
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if (tpmalg < 0)
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return log_error_errno(tpmalg, "Unsupported PCR bank");
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@@ -848,29 +804,20 @@ static int verb_sign(int argc, char *argv[], void *userdata) {
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tpmalg,
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&pcr_selection);
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- rc = sym_Esys_PolicyPCR(
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- c->esys_context,
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- session->esys_handle,
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- ESYS_TR_NONE,
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- ESYS_TR_NONE,
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- ESYS_TR_NONE,
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- &intermediate_digest,
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- &pcr_selection);
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- if (rc != TSS2_RC_SUCCESS)
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- return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE),
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- "Failed to push PCR policy into TPM: %s", sym_Tss2_RC_Decode(rc));
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-
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- _cleanup_(Esys_Freep) TPM2B_DIGEST *pcr_policy_digest = NULL;
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- rc = sym_Esys_PolicyGetDigest(
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- c->esys_context,
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- session->esys_handle,
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- ESYS_TR_NONE,
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- ESYS_TR_NONE,
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- ESYS_TR_NONE,
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- &pcr_policy_digest);
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- if (rc != TSS2_RC_SUCCESS)
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- return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE),
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- "Failed to get policy digest from TPM: %s", sym_Tss2_RC_Decode(rc));
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+ TPM2B_DIGEST pcr_values = {
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+ .size = p->value_size,
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+ };
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+ assert(sizeof(pcr_values.buffer) >= p->value_size);
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+ memcpy_safe(pcr_values.buffer, p->value, p->value_size);
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+
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+ TPM2B_DIGEST pcr_policy_digest;
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+ r = tpm2_digest_init(TPM2_ALG_SHA256, &pcr_policy_digest);
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+ if (r < 0)
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+ return r;
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+
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+ r = tpm2_calculate_policy_pcr(&pcr_selection, &pcr_values, 1, &pcr_policy_digest);
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+ if (r < 0)
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+ return r;
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_cleanup_(EVP_MD_CTX_freep) EVP_MD_CTX* mdctx = NULL;
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mdctx = EVP_MD_CTX_new();
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@@ -881,7 +828,7 @@ static int verb_sign(int argc, char *argv[], void *userdata) {
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return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE),
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"Failed to initialize signature context.");
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- if (EVP_DigestSignUpdate(mdctx, pcr_policy_digest->buffer, pcr_policy_digest->size) != 1)
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+ if (EVP_DigestSignUpdate(mdctx, pcr_policy_digest.buffer, pcr_policy_digest.size) != 1)
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return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE),
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"Failed to sign data.");
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@@ -913,7 +860,7 @@ static int verb_sign(int argc, char *argv[], void *userdata) {
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r = json_build(&bv, JSON_BUILD_OBJECT(
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JSON_BUILD_PAIR("pcrs", JSON_BUILD_VARIANT(a)), /* PCR mask */
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JSON_BUILD_PAIR("pkfp", JSON_BUILD_HEX(pubkey_fp, pubkey_fp_size)), /* SHA256 fingerprint of public key (DER) used for the signature */
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- JSON_BUILD_PAIR("pol", JSON_BUILD_HEX(pcr_policy_digest->buffer, pcr_policy_digest->size)), /* TPM2 policy hash that is signed */
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+ JSON_BUILD_PAIR("pol", JSON_BUILD_HEX(pcr_policy_digest.buffer, pcr_policy_digest.size)), /* TPM2 policy hash that is signed */
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JSON_BUILD_PAIR("sig", JSON_BUILD_BASE64(sig, ss)))); /* signature data */
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if (r < 0)
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return log_error_errno(r, "Failed to build JSON object: %m");
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