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187 lines
8.1 KiB
187 lines
8.1 KiB
8 months ago
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From 3fb5fadcb2c26e9e7da5de8f8bda0fa0e987c443 Mon Sep 17 00:00:00 2001
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From: Dan Streetman <ddstreet@ieee.org>
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Date: Wed, 14 Jun 2023 13:17:21 -0400
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Subject: [PATCH] tpm2: cache TPM algorithms
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Cache the supported algorithms when creating a new context.
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(cherry picked from commit cbc92a3172609238db572b86fa7da5e543e6a4dd)
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Related: RHEL-16182
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---
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src/shared/tpm2-util.c | 84 +++++++++++++++++++++++++++---------------
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src/shared/tpm2-util.h | 4 +-
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src/test/test-tpm2.c | 10 ++---
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3 files changed, 62 insertions(+), 36 deletions(-)
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diff --git a/src/shared/tpm2-util.c b/src/shared/tpm2-util.c
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index d38e260f9a..c05c636745 100644
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--- a/src/shared/tpm2-util.c
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+++ b/src/shared/tpm2-util.c
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@@ -199,6 +199,44 @@ static int tpm2_cache_capabilities(Tpm2Context *c) {
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assert(c);
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+ /* Cache the algorithms. The spec indicates supported algorithms can only be modified during runtime
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+ * by the SetAlgorithmSet() command. Unfortunately, the spec doesn't require a TPM reinitialization
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+ * after changing the algorithm set (unless the PCR algorithms are changed). However, the spec also
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+ * indicates the TPM behavior after SetAlgorithmSet() is "vendor-dependent", giving the example of
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+ * flushing sessions and objects, erasing policies, etc. So, if the algorithm set is programatically
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+ * changed while we are performing some operation, it's reasonable to assume it will break us even if
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+ * we don't cache the algorithms, thus they should be "safe" to cache. */
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+ TPM2_ALG_ID current_alg = TPM2_ALG_FIRST;
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+ for (;;) {
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+ r = tpm2_get_capability(
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+ c,
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+ TPM2_CAP_ALGS,
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+ (uint32_t) current_alg, /* The spec states to cast TPM2_ALG_ID to uint32_t. */
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+ TPM2_MAX_CAP_ALGS,
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+ &capability);
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+ if (r < 0)
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+ return r;
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+
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+ TPML_ALG_PROPERTY algorithms = capability.algorithms;
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+
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+ /* We should never get 0; the TPM must support some algorithms, and it must not set 'more' if
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+ * there are no more. */
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+ assert(algorithms.count > 0);
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+
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+ if (!GREEDY_REALLOC_APPEND(
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+ c->capability_algorithms,
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+ c->n_capability_algorithms,
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+ algorithms.algProperties,
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+ algorithms.count))
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+ return log_oom();
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+
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+ if (r == 0)
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+ break;
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+
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+ /* Set current_alg to alg id after last alg id the TPM provided */
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+ current_alg = algorithms.algProperties[algorithms.count - 1].alg + 1;
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+ }
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+
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/* Cache the command capabilities. The spec isn't actually clear if commands can be added/removed
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* while running, but that would be crazy, so let's hope it is not possbile. */
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TPM2_CC current_cc = TPM2_CC_FIRST;
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@@ -255,35 +293,26 @@ static int tpm2_cache_capabilities(Tpm2Context *c) {
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return 0;
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}
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-/* Get the TPMA_ALGORITHM for a TPM2_ALG_ID.
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- *
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- * Returns 1 if the TPM supports the algorithm and the TPMA_ALGORITHM is provided, or 0 if the TPM does not
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- * support the algorithm, or < 0 for any errors. */
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-static int tpm2_get_capability_alg(Tpm2Context *c, TPM2_ALG_ID alg, TPMA_ALGORITHM *ret) {
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- TPMU_CAPABILITIES capability;
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- int r;
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-
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+/* Get the TPMA_ALGORITHM for a TPM2_ALG_ID. Returns true if the TPM supports the algorithm and the
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+ * TPMA_ALGORITHM is provided, otherwise false. */
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+static bool tpm2_get_capability_alg(Tpm2Context *c, TPM2_ALG_ID alg, TPMA_ALGORITHM *ret) {
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assert(c);
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- /* The spec explicitly states the TPM2_ALG_ID should be cast to uint32_t. */
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- r = tpm2_get_capability(c, TPM2_CAP_ALGS, (uint32_t) alg, 1, &capability);
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- if (r < 0)
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- return r;
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-
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- TPML_ALG_PROPERTY algorithms = capability.algorithms;
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- if (algorithms.count == 0 || algorithms.algProperties[0].alg != alg) {
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- log_debug("TPM does not support alg 0x%02" PRIx16 ".", alg);
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- return 0;
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- }
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+ FOREACH_ARRAY(alg_prop, c->capability_algorithms, c->n_capability_algorithms)
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+ if (alg_prop->alg == alg) {
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+ if (ret)
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+ *ret = alg_prop->algProperties;
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+ return true;
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+ }
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+ log_debug("TPM does not support alg 0x%02" PRIx16 ".", alg);
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if (ret)
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- *ret = algorithms.algProperties[0].algProperties;
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+ *ret = 0;
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- return 1;
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+ return false;
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}
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-/* Returns 1 if the TPM supports the alg, 0 if the TPM does not support the alg, or < 0 for any error. */
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-int tpm2_supports_alg(Tpm2Context *c, TPM2_ALG_ID alg) {
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+bool tpm2_supports_alg(Tpm2Context *c, TPM2_ALG_ID alg) {
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return tpm2_get_capability_alg(c, alg, NULL);
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}
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@@ -473,6 +502,7 @@ static Tpm2Context *tpm2_context_free(Tpm2Context *c) {
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c->tcti_context = mfree(c->tcti_context);
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c->tcti_dl = safe_dlclose(c->tcti_dl);
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+ c->capability_algorithms = mfree(c->capability_algorithms);
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c->capability_commands = mfree(c->capability_commands);
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return mfree(c);
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@@ -598,16 +628,10 @@ int tpm2_context_new(const char *device, Tpm2Context **ret_context) {
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return r;
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/* We require AES and CFB support for session encryption. */
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- r = tpm2_supports_alg(context, TPM2_ALG_AES);
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- if (r < 0)
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- return r;
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- if (r == 0)
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+ if (!tpm2_supports_alg(context, TPM2_ALG_AES))
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return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "TPM does not support AES.");
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- r = tpm2_supports_alg(context, TPM2_ALG_CFB);
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- if (r < 0)
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- return r;
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- if (r == 0)
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+ if (!tpm2_supports_alg(context, TPM2_ALG_CFB))
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return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "TPM does not support CFB.");
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if (!tpm2_supports_tpmt_sym_def(context, &SESSION_TEMPLATE_SYM_AES_128_CFB))
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diff --git a/src/shared/tpm2-util.h b/src/shared/tpm2-util.h
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index 1ca1a2e503..64a2fd3677 100644
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--- a/src/shared/tpm2-util.h
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+++ b/src/shared/tpm2-util.h
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@@ -62,6 +62,8 @@ typedef struct {
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ESYS_CONTEXT *esys_context;
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/* Some selected cached capabilities of the TPM */
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+ TPMS_ALG_PROPERTY *capability_algorithms;
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+ size_t n_capability_algorithms;
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TPMA_CC *capability_commands;
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size_t n_capability_commands;
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TPML_PCR_SELECTION capability_pcrs;
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@@ -86,7 +88,7 @@ int tpm2_handle_new(Tpm2Context *context, Tpm2Handle **ret_handle);
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Tpm2Handle *tpm2_handle_free(Tpm2Handle *handle);
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DEFINE_TRIVIAL_CLEANUP_FUNC(Tpm2Handle*, tpm2_handle_free);
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-int tpm2_supports_alg(Tpm2Context *c, TPM2_ALG_ID alg);
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+bool tpm2_supports_alg(Tpm2Context *c, TPM2_ALG_ID alg);
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bool tpm2_supports_command(Tpm2Context *c, TPM2_CC command);
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bool tpm2_test_parms(Tpm2Context *c, TPMI_ALG_PUBLIC alg, const TPMU_PUBLIC_PARMS *parms);
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diff --git a/src/test/test-tpm2.c b/src/test/test-tpm2.c
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index dfc8b98e08..8fd859b83d 100644
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--- a/src/test/test-tpm2.c
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+++ b/src/test/test-tpm2.c
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@@ -651,13 +651,13 @@ TEST(tpm_required_tests) {
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assert_se(tpm2_test_parms(c, TPM2_ALG_SYMCIPHER, &parms));
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/* Test invalid algs */
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- assert_se(tpm2_supports_alg(c, TPM2_ALG_ERROR) == 0);
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- assert_se(tpm2_supports_alg(c, TPM2_ALG_LAST + 1) == 0);
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+ assert_se(!tpm2_supports_alg(c, TPM2_ALG_ERROR));
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+ assert_se(!tpm2_supports_alg(c, TPM2_ALG_LAST + 1));
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/* Test valid algs */
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- assert_se(tpm2_supports_alg(c, TPM2_ALG_RSA) == 1);
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- assert_se(tpm2_supports_alg(c, TPM2_ALG_AES) == 1);
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- assert_se(tpm2_supports_alg(c, TPM2_ALG_CFB) == 1);
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+ assert_se(tpm2_supports_alg(c, TPM2_ALG_RSA));
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+ assert_se(tpm2_supports_alg(c, TPM2_ALG_AES));
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+ assert_se(tpm2_supports_alg(c, TPM2_ALG_CFB));
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/* Test invalid commands */
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assert_se(!tpm2_supports_command(c, TPM2_CC_FIRST - 1));
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