[coreboot-gerrit] New patch to review for coreboot: tpm2: implement and use pcr_extend command
Martin Roth (martinroth@google.com)
gerrit at coreboot.org
Tue Jul 12 22:06:39 CEST 2016
Martin Roth (martinroth at google.com) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/15639
-gerrit
commit 5ead87b1d31881d69cb17ec5eaff9347861dc9bd
Author: Vadim Bendebury <vbendeb at chromium.org>
Date: Sun Jul 3 22:20:17 2016 -0700
tpm2: implement and use pcr_extend command
TPM PCRs are used in Chrome OS for two purposes: to communicate
crucial information from RO firmware and to protect FW and kernel
rollback counters from being deleted.
As implemented in a TPM1 compatible way, the PCR extension command
requires a prebuilt digest to calculate a new PCR value.
TPM2 specification introduces a PCR_Event command, where the TPM
itself calculates the digest of an arbitrary length string, and then
uses the calculated digest for PCR extension. PCR_Event could be a
better option for Chrome OS, this needs to be investigated separately.
BRANCH=none
BUG=chrome-os-partner:50645
TEST=verified that the two PCRs are successfully extended before the
RW firmware is called.
Change-Id: I38fc88172de8ec8bef56fec026f83058480c8010
Signed-off-by: Martin Roth <martinroth at chromium.org>
Original-Commit-Id: 73388139db3ffaf61a3d9027522c5ebecb3ad051
Original-Change-Id: I1a9bab7396fdb652e2e3bc8529b828ea3423d851
Original-Signed-off-by: Vadim Bendebury <vbendeb at chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/358098
Original-Reviewed-by: Aaron Durbin <adurbin at chromium.org>
Original-Reviewed-by: Darren Krahn <dkrahn at chromium.org>
---
src/lib/tpm2_marshaling.c | 37 +++++++++++++++++++++++++++++++++++++
src/lib/tpm2_tlcl.c | 21 ++++++++++++++++++++-
src/lib/tpm2_tlcl_structures.h | 30 +++++++++++++++++++++++++++++-
3 files changed, 86 insertions(+), 2 deletions(-)
diff --git a/src/lib/tpm2_marshaling.c b/src/lib/tpm2_marshaling.c
index 00c8f7d..ab9a928 100644
--- a/src/lib/tpm2_marshaling.c
+++ b/src/lib/tpm2_marshaling.c
@@ -201,6 +201,27 @@ static void marshal_TPMS_NV_PUBLIC(void **buffer,
marshal_u16(buffer, nvpub->dataSize, buffer_space);
}
+static void marshal_TPMT_HA(void **buffer,
+ TPMT_HA *tpmtha,
+ size_t *buffer_space)
+{
+ marshal_TPMI_ALG_HASH(buffer, tpmtha->hashAlg, buffer_space);
+ marshal_blob(buffer, tpmtha->digest.sha256,
+ sizeof(tpmtha->digest.sha256),
+ buffer_space);
+}
+
+static void marshal_TPML_DIGEST_VALUES(void **buffer,
+ TPML_DIGEST_VALUES *dvalues,
+ size_t *buffer_space)
+{
+ int i;
+
+ marshal_u32(buffer, dvalues->count, buffer_space);
+ for (i = 0; i < dvalues->count; i++)
+ marshal_TPMT_HA(buffer, &dvalues->digests[i], buffer_space);
+}
+
static void marshal_session_header(void **buffer,
struct tpm2_session_header *session_header,
size_t *buffer_space)
@@ -312,6 +333,17 @@ static void marshal_nv_write_lock(void **buffer,
ARRAY_SIZE(handles), buffer_space);
}
+static void marshal_pcr_extend(void **buffer,
+ struct tpm2_pcr_extend_cmd *command_body,
+ size_t *buffer_space)
+{
+ uint32_t handle = command_body->pcrHandle;
+
+ marshal_common_session_header(buffer, &handle, 1, buffer_space);
+ marshal_TPML_DIGEST_VALUES(buffer,
+ &command_body->digests, buffer_space);
+}
+
static void marshal_nv_read(void **buffer,
struct tpm2_nv_read_cmd *command_body,
size_t *buffer_space)
@@ -385,6 +417,10 @@ int tpm_marshal_command(TPM_CC command, void *tpm_command_body,
marshal_clear(&cmd_body, &body_size);
break;
+ case TPM2_PCR_Extend:
+ marshal_pcr_extend(&cmd_body, tpm_command_body, &body_size);
+ break;
+
default:
body_size = 0;
printk(BIOS_INFO, "%s:%d:Request to marshal unsupported command %#x\n",
@@ -547,6 +583,7 @@ struct tpm2_response *tpm_unmarshal_response(TPM_CC command,
case TPM2_NV_DefineSpace:
case TPM2_NV_Write:
case TPM2_NV_WriteLock:
+ case TPM2_PCR_Extend:
/* Session data included in response can be safely ignored. */
cr_size = 0;
break;
diff --git a/src/lib/tpm2_tlcl.c b/src/lib/tpm2_tlcl.c
index 3003400..d9f9d37 100644
--- a/src/lib/tpm2_tlcl.c
+++ b/src/lib/tpm2_tlcl.c
@@ -65,10 +65,29 @@ uint32_t tlcl_assert_physical_presence(void)
return TPM_SUCCESS;
}
+/*
+ * The caller will provide the digest in a 32 byte buffer, let's consider it a
+ * sha256 digest.
+ */
uint32_t tlcl_extend(int pcr_num, const uint8_t *in_digest,
uint8_t *out_digest)
{
- printk(BIOS_INFO, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+ struct tpm2_pcr_extend_cmd pcr_ext_cmd;
+ struct tpm2_response *response;
+
+ pcr_ext_cmd.pcrHandle = HR_PCR + pcr_num;
+ pcr_ext_cmd.digests.count = 1;
+ pcr_ext_cmd.digests.digests[0].hashAlg = TPM_ALG_SHA256;
+ memcpy(pcr_ext_cmd.digests.digests[0].digest.sha256, in_digest,
+ sizeof(pcr_ext_cmd.digests.digests[0].digest.sha256));
+
+ response = tpm_process_command(TPM2_PCR_Extend, &pcr_ext_cmd);
+
+ printk(BIOS_INFO, "%s: response is %x\n",
+ __func__, response ? response->hdr.tpm_code : -1);
+ if (!response || response->hdr.tpm_code)
+ return TPM_E_IOERROR;
+
return TPM_SUCCESS;
}
diff --git a/src/lib/tpm2_tlcl_structures.h b/src/lib/tpm2_tlcl_structures.h
index 1e7fcf0..36a3e8b 100644
--- a/src/lib/tpm2_tlcl_structures.h
+++ b/src/lib/tpm2_tlcl_structures.h
@@ -25,11 +25,12 @@ typedef uint32_t TPM_CC;
typedef uint32_t TPM_HANDLE;
typedef uint32_t TPM_RC;
typedef uint8_t TPMI_YES_NO;
+typedef TPM_ALG_ID TPMI_ALG_HASH;
+typedef TPM_HANDLE TPMI_DH_PCR;
typedef TPM_HANDLE TPMI_RH_NV_INDEX;
typedef TPM_HANDLE TPMI_RH_PROVISION;
typedef TPM_HANDLE TPMI_SH_AUTH_SESSION;
typedef TPM_HANDLE TPM_RH;
-typedef TPM_ALG_ID TPMI_ALG_HASH;
/* Some hardcoded algorithm values. */
#define TPM_ALG_HMAC ((TPM_ALG_ID)0x0005)
@@ -37,6 +38,8 @@ typedef TPM_ALG_ID TPMI_ALG_HASH;
#define TPM_ALG_SHA1 ((TPM_ALG_ID)0x0004)
#define TPM_ALG_SHA256 ((TPM_ALG_ID)0x000b)
+#define SHA256_DIGEST_SIZE 32
+
/* Some hardcoded hierarchies. */
#define TPM_RH_NULL 0x40000007
#define TPM_RS_PW 0x40000009
@@ -64,11 +67,13 @@ struct tpm_header {
#define TPM2_Startup ((TPM_CC)0x00000144)
#define TPM2_NV_Read ((TPM_CC)0x0000014E)
#define TPM2_GetCapability ((TPM_CC)0x0000017A)
+#define TPM2_PCR_Extend ((TPM_CC)0x00000182)
/* Startup values. */
#define TPM_SU_CLEAR 0
#define TPM_SU_STATE 1
+#define TPM_HT_PCR 0x00
#define TPM_HT_NV_INDEX 0x01
#define TPM_HT_HMAC_SESSION 0x02
#define TPM_HT_POLICY_SESSION 0x03
@@ -241,6 +246,24 @@ typedef union {
TPM2B b;
} TPM2B_MAX_NV_BUFFER;
+/*
+ * This is a union, but as of now we support just one digest - sha256, so
+ * there is just one element.
+ */
+typedef union {
+ uint8_t sha256[SHA256_DIGEST_SIZE];
+} TPMU_HA;
+
+typedef struct {
+ TPMI_ALG_HASH hashAlg;
+ TPMU_HA digest;
+} TPMT_HA;
+
+typedef struct {
+ uint32_t count;
+ TPMT_HA digests[1]; /* Limit max number of hashes to 1. */
+} TPML_DIGEST_VALUES;
+
struct nv_read_response {
uint32_t params_size;
TPM2B_MAX_NV_BUFFER buffer;
@@ -306,4 +329,9 @@ struct tpm2_nv_write_lock_cmd {
TPMI_RH_NV_INDEX nvIndex;
};
+struct tpm2_pcr_extend_cmd {
+ TPMI_DH_PCR pcrHandle;
+ TPML_DIGEST_VALUES digests;
+};
+
#endif // __SRC_LIB_TPM2_TLCL_STRUCTURES_H
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