u2f: do not commit state changes on TPM command context.

g2f_attestation_cert() is another function which is invoked on the TPM
command context, when virtual TPM NVMEM spaces are read.

One of the side effects of invoking of g2f_attestation_cert() is the
creation of the U2F state, if it did not exist before. In this case
the state should not be immediately committed to the NVMEM, the commit
will happen when the TPM command execution is completed.

BUG=b:199981251
TEST=running ./test/tpm_test/tpmtest.py does not trigger the 'attempt
     to commit in unlocked state' message any more.
     'make buildall' and 'make CRYTPO_TEST=1 BOARD=cr50' pass

Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Change-Id: I708e8807ffd3207cc6ab84a0e380908e715f7a15
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3482487
Reviewed-by: Mary Ruthven <mruthven@chromium.org>

1 files changed, 22 insertions, 10 deletions

diff --git a/board/cr50/u2f_state_load.c b/board/cr50/u2f_state_load.c
index 8e92199bb7..4f602b9029 100644
--- a/board/cr50/u2f_state_load.c
+++ b/board/cr50/u2f_state_load.c
@@ -19,7 +19,8 @@ static const uint8_t k_salt_deprecated = NVMEM_VAR_U2F_SALT;
 
 #define CPRINTF(format, args...) cprintf(CC_EXTENSION, format, ##args)
 
-bool u2f_load_or_create_state(struct u2f_state *state, bool force_create)
+bool u2f_load_or_create_state(struct u2f_state *state, bool force_create,
+			      bool commit)
 {
 	bool g2f_secret_was_created = false;
 
@@ -62,7 +63,7 @@ bool u2f_load_or_create_state(struct u2f_state *state, bool force_create)
 
 		if (write_tpm_nvmem_hidden(
 			    TPM_HIDDEN_U2F_KEK, sizeof(state->hmac_key),
-			    state->hmac_key, 1 /* commit */) == TPM_WRITE_FAIL)
+			    state->hmac_key, commit) == TPM_WRITE_FAIL)
 			return false;
 	}
 
@@ -92,10 +93,9 @@ bool u2f_load_or_create_state(struct u2f_state *state, bool force_create)
 		if (!g2f_secret_was_created)
 			state->drbg_entropy_size = 32;
 
-		if (write_tpm_nvmem_hidden(TPM_HIDDEN_U2F_KH_SALT,
-					   state->drbg_entropy_size,
-					   state->drbg_entropy,
-					   1 /* commit */) == TPM_WRITE_FAIL) {
+		if (write_tpm_nvmem_hidden(
+			    TPM_HIDDEN_U2F_KH_SALT, state->drbg_entropy_size,
+			    state->drbg_entropy, commit) == TPM_WRITE_FAIL) {
 			state->drbg_entropy_size = 0;
 			return false;
 		}
@@ -126,12 +126,23 @@ bool u2f_load_or_create_state(struct u2f_state *state, bool force_create)
 static bool u2f_state_loaded;
 static struct u2f_state u2f_state;
 
+static struct u2f_state *u2f_get_state_common(bool commit)
+{
+	if (!u2f_state_loaded) {
+		u2f_state_loaded =
+			u2f_load_or_create_state(&u2f_state, false, commit);
+	}
+	return u2f_state_loaded ? &u2f_state : NULL;
+}
+
 struct u2f_state *u2f_get_state(void)
 {
-	if (!u2f_state_loaded)
-		u2f_state_loaded = u2f_load_or_create_state(&u2f_state, false);
+	return u2f_get_state_common(true);
+}
 
-	return u2f_state_loaded ? &u2f_state : NULL;
+struct u2f_state *u2f_get_state_no_commit(void)
+{
+	return u2f_get_state_common(false);
 }
 
 enum ec_error_list u2f_gen_kek_seed(void)
@@ -193,7 +204,8 @@ enum ec_error_list u2f_update_keys(void)
 	if (!state || state->drbg_entropy_size != sizeof(state->drbg_entropy)) {
 		result = u2f_zeroize_keys();
 		/* Force creation of new keys. */
-		u2f_state_loaded = u2f_load_or_create_state(&u2f_state, true);
+		u2f_state_loaded =
+			u2f_load_or_create_state(&u2f_state, true, true);
 
 		/* try to load again */
 		state = u2f_get_state();