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From 6aa706de80fa716b7d54adfc4094884707518d95 Mon Sep 17 00:00:00 2001
From: Dan Streetman <ddstreet@ieee.org>
Date: Wed, 14 Dec 2022 10:46:13 -0500
Subject: [PATCH] tpm2: add tpm2_digest_*() functions
These functions allow extending (or initializing) a TPM2B_DIGEST with additional
data, using a specified hash operation. This is needed to perform hash
calculations instead of relying on the TPM to perform the calculations in
trial sessions.
(cherry picked from commit da92d39a8577e792075009782d419b423414ad6e)
Related: RHEL-16182
---
src/shared/tpm2-util.c | 86 ++++++++++++++++++++++++++++++++---
src/shared/tpm2-util.h | 13 ++++++
src/test/test-tpm2.c | 100 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 194 insertions(+), 5 deletions(-)
diff --git a/src/shared/tpm2-util.c b/src/shared/tpm2-util.c
index 002e2c01da..d397c505f5 100644
--- a/src/shared/tpm2-util.c
+++ b/src/shared/tpm2-util.c
@@ -1384,6 +1384,83 @@ static void hash_pin(const char *pin, size_t len, TPM2B_AUTH *auth) {
sha256_finish_ctx(&hash, auth->buffer);
}
+/* Hash data into the digest.
+ *
+ * If 'extend' is true, the hashing operation starts with the existing digest hash (and the digest is
+ * required to have a hash and its size must be correct). If 'extend' is false, the digest size is
+ * initialized to the correct size for 'alg' and the hashing operation does not include any existing digest
+ * hash. If 'extend' is false and no data is provided, the digest is initialized to a zero digest.
+ *
+ * On success, the digest hash will be updated with the hashing operation result and the digest size will be
+ * correct for 'alg'.
+ *
+ * This currently only provides SHA256, so 'alg' must be TPM2_ALG_SHA256. */
+int tpm2_digest_many(
+ TPMI_ALG_HASH alg,
+ TPM2B_DIGEST *digest,
+ const struct iovec data[],
+ size_t n_data,
+ bool extend) {
+
+ struct sha256_ctx ctx;
+
+ assert(digest);
+ assert(data || n_data == 0);
+
+ if (alg != TPM2_ALG_SHA256)
+ return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
+ "Hash algorithm not supported: 0x%x", alg);
+
+ if (extend && digest->size != SHA256_DIGEST_SIZE)
+ return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
+ "Digest size 0x%x, require 0x%x",
+ digest->size, (unsigned)SHA256_DIGEST_SIZE);
+
+ /* Since we're hardcoding SHA256 (for now), we can check this at compile time. */
+ assert_cc(sizeof(digest->buffer) >= SHA256_DIGEST_SIZE);
+
+ CLEANUP_ERASE(ctx);
+
+ sha256_init_ctx(&ctx);
+
+ if (extend)
+ sha256_process_bytes(digest->buffer, digest->size, &ctx);
+ else {
+ *digest = (TPM2B_DIGEST){ .size = SHA256_DIGEST_SIZE, };
+ if (n_data == 0) /* If not extending and no data, return zero hash */
+ return 0;
+ }
+
+ for (size_t i = 0; i < n_data; i++)
+ sha256_process_bytes(data[i].iov_base, data[i].iov_len, &ctx);
+
+ sha256_finish_ctx(&ctx, digest->buffer);
+
+ return 0;
+}
+
+/* Same as tpm2_digest_many() but data is contained in TPM2B_DIGEST[]. The digests may be any size digests. */
+int tpm2_digest_many_digests(
+ TPMI_ALG_HASH alg,
+ TPM2B_DIGEST *digest,
+ const TPM2B_DIGEST data[],
+ size_t n_data,
+ bool extend) {
+
+ _cleanup_free_ struct iovec *iovecs = NULL;
+
+ assert(data || n_data == 0);
+
+ iovecs = new(struct iovec, n_data);
+ if (!iovecs)
+ return log_oom();
+
+ for (size_t i = 0; i < n_data; i++)
+ iovecs[i] = IOVEC_MAKE((void*) data[i].buffer, data[i].size);
+
+ return tpm2_digest_many(alg, digest, iovecs, n_data, extend);
+}
+
static bool tpm2_is_encryption_session(Tpm2Context *c, const Tpm2Handle *session) {
TPMA_SESSION flags = 0;
TSS2_RC rc;
@@ -1868,11 +1945,10 @@ static int tpm2_build_sealing_policy(
/* TPM2_VerifySignature() will only verify the RSA part of the RSA+SHA256 signature,
* hence we need to do the SHA256 part ourselves, first */
- TPM2B_DIGEST signature_hash = {
- .size = SHA256_DIGEST_SIZE,
- };
- assert(sizeof(signature_hash.buffer) >= SHA256_DIGEST_SIZE);
- sha256_direct(approved_policy->buffer, approved_policy->size, signature_hash.buffer);
+ TPM2B_DIGEST signature_hash = *approved_policy;
+ r = tpm2_digest_rehash(TPM2_ALG_SHA256, &signature_hash);
+ if (r < 0)
+ return r;
TPMT_SIGNATURE policy_signature = {
.sigAlg = TPM2_ALG_RSASSA,
diff --git a/src/shared/tpm2-util.h b/src/shared/tpm2-util.h
index 3c4d045197..2744cd13bb 100644
--- a/src/shared/tpm2-util.h
+++ b/src/shared/tpm2-util.h
@@ -4,6 +4,7 @@
#include <stdbool.h>
#include "bitfield.h"
+#include "io-util.h"
#include "json.h"
#include "macro.h"
#include "sha256.h"
@@ -72,6 +73,18 @@ extern TSS2_RC (*sym_Tss2_MU_TPM2B_PUBLIC_Unmarshal)(uint8_t const buffer[], siz
int dlopen_tpm2(void);
+int tpm2_digest_many(TPMI_ALG_HASH alg, TPM2B_DIGEST *digest, const struct iovec data[], size_t count, bool extend);
+static inline int tpm2_digest_buffer(TPMI_ALG_HASH alg, TPM2B_DIGEST *digest, const void *data, size_t len, bool extend) {
+ return tpm2_digest_many(alg, digest, &IOVEC_MAKE((void*) data, len), 1, extend);
+}
+int tpm2_digest_many_digests(TPMI_ALG_HASH alg, TPM2B_DIGEST *digest, const TPM2B_DIGEST data[], size_t count, bool extend);
+static inline int tpm2_digest_rehash(TPMI_ALG_HASH alg, TPM2B_DIGEST *digest) {
+ return tpm2_digest_many(alg, digest, NULL, 0, true);
+}
+static inline int tpm2_digest_init(TPMI_ALG_HASH alg, TPM2B_DIGEST *digest) {
+ return tpm2_digest_many(alg, digest, NULL, 0, false);
+}
+
int tpm2_seal(const char *device, uint32_t hash_pcr_mask, const void *pubkey, size_t pubkey_size, uint32_t pubkey_pcr_mask, const char *pin, void **ret_secret, size_t *ret_secret_size, void **ret_blob, size_t *ret_blob_size, void **ret_pcr_hash, size_t *ret_pcr_hash_size, uint16_t *ret_pcr_bank, uint16_t *ret_primary_alg, void **ret_srk_buf, size_t *ret_srk_buf_size);
int tpm2_unseal(const char *device, uint32_t hash_pcr_mask, uint16_t pcr_bank, const void *pubkey, size_t pubkey_size, uint32_t pubkey_pcr_mask, JsonVariant *signature, const char *pin, uint16_t primary_alg, const void *blob, size_t blob_size, const void *policy_hash, size_t policy_hash_size, const void *srk_buf, size_t srk_buf_size, void **ret_secret, size_t *ret_secret_size);
diff --git a/src/test/test-tpm2.c b/src/test/test-tpm2.c
index 2c696e443d..dfbea7b19a 100644
--- a/src/test/test-tpm2.c
+++ b/src/test/test-tpm2.c
@@ -1,5 +1,6 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#include "hexdecoct.h"
#include "tpm2-util.h"
#include "tests.h"
@@ -500,6 +501,105 @@ TEST(tpm2_get_primary_template) {
}
}
+static bool digest_check(const TPM2B_DIGEST *digest, const char *expect) {
+ _cleanup_free_ char *h = NULL;
+
+ assert_se(digest);
+ assert_se(expect);
+
+ h = hexmem(digest->buffer, digest->size);
+ assert_se(h);
+
+ return streq(expect, h);
+}
+
+static void digest_init_sha256(TPM2B_DIGEST *digest, const char *hash) {
+ _cleanup_free_ void *h = NULL;
+ size_t s = 0;
+
+ assert_se(strlen(hash) == SHA256_DIGEST_SIZE * 2);
+ assert_se(strlen(hash) <= sizeof(digest->buffer) * 2);
+
+ assert_se(unhexmem(hash, strlen(hash), &h, &s) == 0);
+ assert_se(s == SHA256_DIGEST_SIZE);
+
+ memcpy_safe(digest->buffer, h, s);
+ digest->size = s;
+
+ assert_se(digest_check(digest, hash));
+}
+
+TEST(digest_many) {
+ TPM2B_DIGEST d, d0, d1, d2, d3, d4;
+
+ digest_init_sha256(&d0, "0000000000000000000000000000000000000000000000000000000000000000");
+ digest_init_sha256(&d1, "17b7703d9d00776310ba032e88c1a8c2a9c630ebdd799db622f6631530789175");
+ digest_init_sha256(&d2, "12998c017066eb0d2a70b94e6ed3192985855ce390f321bbdb832022888bd251");
+ digest_init_sha256(&d3, "c3a65887fedd3fb4f5d0047e906dff830bcbd1293160909eb4b05f485e7387ad");
+ digest_init_sha256(&d4, "6491fb4bc08fc0b2ef47fc63db57e249917885e69d8c0d99667df83a59107a33");
+
+ /* tpm2_digest_init, tpm2_digest_rehash */
+ d = (TPM2B_DIGEST){ .size = 1, .buffer = { 2, }, };
+ assert_se(tpm2_digest_init(TPM2_ALG_SHA256, &d) == 0);
+ assert_se(digest_check(&d, "0000000000000000000000000000000000000000000000000000000000000000"));
+ assert_se(tpm2_digest_rehash(TPM2_ALG_SHA256, &d) == 0);
+ assert_se(digest_check(&d, "66687aadf862bd776c8fc18b8e9f8e20089714856ee233b3902a591d0d5f2925"));
+
+ d = d1;
+ assert_se(tpm2_digest_rehash(TPM2_ALG_SHA256, &d) == 0);
+ assert_se(digest_check(&d, "ab55014b5ace12ba70c3acc887db571585a83539aad3633d252a710f268f405c"));
+ assert_se(tpm2_digest_init(TPM2_ALG_SHA256, &d) == 0);
+ assert_se(digest_check(&d, "0000000000000000000000000000000000000000000000000000000000000000"));
+
+ /* tpm2_digest_many_digests */
+ assert_se(tpm2_digest_many_digests(TPM2_ALG_SHA256, &d, &d2, 1, false) == 0);
+ assert_se(digest_check(&d, "56571a1be3fbeab18d215f549095915a004b5788ca0d535be668559129a76f25"));
+ assert_se(tpm2_digest_many_digests(TPM2_ALG_SHA256, &d, &d2, 1, true) == 0);
+ assert_se(digest_check(&d, "99dedaee8f4d8d10a8be184399fde8740d5e17ff783ee5c288a4486e4ce3a1fe"));
+
+ const TPM2B_DIGEST da1[] = { d2, d3, };
+ assert_se(tpm2_digest_many_digests(TPM2_ALG_SHA256, &d, da1, ELEMENTSOF(da1), false) == 0);
+ assert_se(digest_check(&d, "525aa13ef9a61827778ec3acf16fbb23b65ae8770b8fb2684d3a33f9457dd6d8"));
+ assert_se(tpm2_digest_many_digests(TPM2_ALG_SHA256, &d, da1, ELEMENTSOF(da1), true) == 0);
+ assert_se(digest_check(&d, "399ca2aa98963d1bd81a2b58a7e5cda24bba1be88fb4da9aa73d97706846566b"));
+
+ const TPM2B_DIGEST da2[] = { d3, d2, d0 };
+ assert_se(tpm2_digest_many_digests(TPM2_ALG_SHA256, &d, da2, ELEMENTSOF(da2), false) == 0);
+ assert_se(digest_check(&d, "b26fd22db74d4cd896bff01c61aa498a575e4a553a7fb5a322a5fee36954313e"));
+ assert_se(tpm2_digest_many_digests(TPM2_ALG_SHA256, &d, da2, ELEMENTSOF(da2), true) == 0);
+ assert_se(digest_check(&d, "091e79a5b09d4048df49a680f966f3ff67910afe185c3baf9704c9ca45bcf259"));
+
+ const TPM2B_DIGEST da3[] = { d4, d4, d4, d4, d3, d4, d4, d4, d4, };
+ assert_se(tpm2_digest_many_digests(TPM2_ALG_SHA256, &d, da3, ELEMENTSOF(da3), false) == 0);
+ assert_se(digest_check(&d, "8eca947641b6002df79dfb571a7f78b7d0a61370a366f722386dfbe444d18830"));
+ assert_se(tpm2_digest_many_digests(TPM2_ALG_SHA256, &d, da3, ELEMENTSOF(da3), true) == 0);
+ assert_se(digest_check(&d, "f9ba17bc0bbe8794e9bcbf112e4d59a11eb68fffbcd5516a746e4857829dff04"));
+
+ /* tpm2_digest_buffer */
+ const uint8_t b1[] = { 1, 2, 3, 4, };
+ assert_se(tpm2_digest_buffer(TPM2_ALG_SHA256, &d, b1, ELEMENTSOF(b1), false) == 0);
+ assert_se(digest_check(&d, "9f64a747e1b97f131fabb6b447296c9b6f0201e79fb3c5356e6c77e89b6a806a"));
+ assert_se(tpm2_digest_buffer(TPM2_ALG_SHA256, &d, b1, ELEMENTSOF(b1), true) == 0);
+ assert_se(digest_check(&d, "ff3bd307b287e9b29bb572f6ccfd19deb0106d0c4c3c5cfe8a1d03a396092ed4"));
+
+ const void *b2 = d2.buffer;
+ assert_se(tpm2_digest_buffer(TPM2_ALG_SHA256, &d, b2, d2.size, false) == 0);
+ assert_se(digest_check(&d, "56571a1be3fbeab18d215f549095915a004b5788ca0d535be668559129a76f25"));
+ assert_se(tpm2_digest_buffer(TPM2_ALG_SHA256, &d, b2, d2.size, true) == 0);
+ assert_se(digest_check(&d, "99dedaee8f4d8d10a8be184399fde8740d5e17ff783ee5c288a4486e4ce3a1fe"));
+
+ /* tpm2_digest_many */
+ const struct iovec iov1[] = {
+ IOVEC_MAKE((void*) b1, ELEMENTSOF(b1)),
+ IOVEC_MAKE(d2.buffer, d2.size),
+ IOVEC_MAKE(d3.buffer, d3.size),
+ };
+ assert_se(tpm2_digest_many(TPM2_ALG_SHA256, &d, iov1, ELEMENTSOF(iov1), false) == 0);
+ assert_se(digest_check(&d, "cd7bde4a047af976b6f1b282309976229be59f96a78aa186de32a1aee488ab09"));
+ assert_se(tpm2_digest_many(TPM2_ALG_SHA256, &d, iov1, ELEMENTSOF(iov1), true) == 0);
+ assert_se(digest_check(&d, "02ecb0628264235111e0053e271092981c8b15d59cd46617836bee3149a4ecb0"));
+}
+
#endif /* HAVE_TPM2 */
DEFINE_TEST_MAIN(LOG_DEBUG);
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