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121 lines
4.6 KiB
121 lines
4.6 KiB
From 50375de7b310d361a71521c6abf8e4251027dd3b Mon Sep 17 00:00:00 2001
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From: Dan Streetman <ddstreet@ieee.org>
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Date: Tue, 6 Dec 2022 13:16:43 -0500
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Subject: [PATCH] tpm2: add tpm2_set_auth()
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This provides a function to perform the SetAuth TPM function, which provides
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the authValue for a key.
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(cherry picked from commit 409a65f82901ace5799da0f22f10056105e062fa)
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Related: RHEL-16182
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---
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src/shared/tpm2-util.c | 65 ++++++++++++++++++++++++------------------
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1 file changed, 38 insertions(+), 27 deletions(-)
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diff --git a/src/shared/tpm2-util.c b/src/shared/tpm2-util.c
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index f1950189d5..ac8569878c 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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@@ -1446,6 +1446,31 @@ int tpm2_digest_many_digests(
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return tpm2_digest_many(alg, digest, iovecs, n_data, extend);
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}
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+static int tpm2_set_auth(Tpm2Context *c, const Tpm2Handle *handle, const char *pin) {
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+ TPM2B_AUTH auth = {};
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+ TSS2_RC rc;
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+ int r;
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+
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+ assert(c);
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+ assert(handle);
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+
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+ if (!pin)
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+ return 0;
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+
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+ CLEANUP_ERASE(auth);
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+
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+ r = tpm2_digest_buffer(TPM2_ALG_SHA256, &auth, pin, strlen(pin), /* extend= */ false);
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+ if (r < 0)
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+ return r;
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+
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+ rc = sym_Esys_TR_SetAuth(c->esys_context, handle->esys_handle, &auth);
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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 load PIN in TPM: %s", sym_Tss2_RC_Decode(rc));
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+
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+ return 0;
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+}
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+
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static bool tpm2_is_encryption_session(Tpm2Context *c, const Tpm2Handle *session) {
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TPMA_SESSION flags = 0;
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TSS2_RC rc;
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@@ -1464,7 +1489,6 @@ static int tpm2_make_encryption_session(
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Tpm2Context *c,
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const Tpm2Handle *primary,
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const Tpm2Handle *bind_key,
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- const char *pin,
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Tpm2Handle **ret_session) {
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static const TPMT_SYM_DEF symmetric = {
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@@ -1480,30 +1504,6 @@ static int tpm2_make_encryption_session(
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assert(c);
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assert(ret_session);
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- /*
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- * if a pin is set for the seal object, use it to bind the session
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- * key to that object. This prevents active bus interposers from
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- * faking a TPM and seeing the unsealed value. An active interposer
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- * could fake a TPM, satisfying the encrypted session, and just
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- * forward everything to the *real* TPM.
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- */
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- if (pin) {
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- TPM2B_AUTH auth = {};
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-
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- CLEANUP_ERASE(auth);
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-
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- r = tpm2_digest_buffer(TPM2_ALG_SHA256, &auth, pin, strlen(pin), /* extend= */ false);
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- if (r < 0)
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- return r;
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-
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- rc = sym_Esys_TR_SetAuth(c->esys_context, bind_key->esys_handle, &auth);
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- if (rc != TSS2_RC_SUCCESS)
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- return log_error_errno(
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- SYNTHETIC_ERRNO(ENOTRECOVERABLE),
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- "Failed to load PIN in TPM: %s",
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- sym_Tss2_RC_Decode(rc));
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- }
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-
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log_debug("Starting HMAC encryption session.");
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/* Start a salted, unbound HMAC session with a well-known key (e.g. primary key) as tpmKey, which
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@@ -2111,7 +2111,7 @@ int tpm2_seal(const char *device,
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/* we cannot use the bind key before its created */
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_cleanup_tpm2_handle_ Tpm2Handle *encryption_session = NULL;
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- r = tpm2_make_encryption_session(c, primary, &TPM2_HANDLE_NONE, NULL, &encryption_session);
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+ r = tpm2_make_encryption_session(c, primary, &TPM2_HANDLE_NONE, &encryption_session);
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if (r < 0)
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return r;
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@@ -2408,8 +2408,19 @@ int tpm2_unseal(const char *device,
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sym_Tss2_RC_Decode(rc));
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}
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+ /*
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+ * if a pin is set for the seal object, use it to bind the session
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+ * key to that object. This prevents active bus interposers from
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+ * faking a TPM and seeing the unsealed value. An active interposer
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+ * could fake a TPM, satisfying the encrypted session, and just
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+ * forward everything to the *real* TPM.
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+ */
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+ r = tpm2_set_auth(c, hmac_key, pin);
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+ if (r < 0)
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+ return r;
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+
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_cleanup_tpm2_handle_ Tpm2Handle *encryption_session = NULL;
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- r = tpm2_make_encryption_session(c, primary, hmac_key, pin, &encryption_session);
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+ r = tpm2_make_encryption_session(c, primary, hmac_key, &encryption_session);
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if (r < 0)
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return r;
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