[SeaBIOS] [PATCH 1/3] tpm: Retrieve the PCR Bank configuration

[Stefan Berger]

Implement tpm20_get_capability and retrieve the PCR Bank configuration
from the TPM using this function.

Signed-off-by: Stefan Berger 
---
 src/std/tcg.h | 29 +++++++++++++++++++++++++++++
 src/tcgbios.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+)

diff --git a/src/std/tcg.h b/src/std/tcg.h
index c59f671..d60ee09 100644
--- a/src/std/tcg.h
+++ b/src/std/tcg.h
@@ -394,12 +394,16 @@ struct tpm_res_sha1complete {
 #define TPM2_CC_SelfTest            0x143
 #define TPM2_CC_Startup             0x144
 #define TPM2_CC_StirRandom          0x146
+#define TPM2_CC_GetCapability       0x17a
 #define TPM2_CC_GetRandom           0x17b
 #define TPM2_CC_PCR_Extend          0x182

/* TPM 2 error codes */
 #define TPM2_RC_INITIALIZE          0x100

+/* TPM 2 Capabilities */
+#define TPM2_CAP_PCRS               0x00000005
+
 /* TPM 2 data structures */

struct tpm2b_stir {
@@ -475,6 +479,31 @@ struct tpm2_req_hierarchycontrol {
     u8 state;
 } PACKED;

+struct tpm2_req_getcapability {
+    struct tpm_req_header hdr;
+    u32 capability;
+    u32 property;
+    u32 propertycount;
+} PACKED;
+
+struct tpm2_res_getcapability {
+    struct tpm_rsp_header hdr;
+    u8 moreData;
+    u32 capability;
+    u8 data[0]; /* capability dependent data */
+} PACKED;
+
+struct tpms_pcr_selection {
+    u16 hashAlg;
+    u8 sizeOfSelect;
+    u8 pcrSelect[0];
+} PACKED;
+
+struct tpml_pcr_selection {
+    u32 count;
+    struct tpms_pcr_selection selections[0];
+} PACKED;
+
 /* TPM 2 log entry */

struct tpml_digest_values_sha1 {
diff --git a/src/tcgbios.c b/src/tcgbios.c
index 334d99b..a79b880 100644
--- a/src/tcgbios.c
+++ b/src/tcgbios.c
@@ -24,6 +24,7 @@
 #include "tcgbios.h"// tpm_*, prototypes
 #include "util.h" // printf, get_keystroke
 #include "stacks.h" // wait_threads, reset
+#include "malloc.h" // malloc_high

/****************************************************************
  * TPM 1.2 commands
@@ -76,6 +77,9 @@ static int TPM_has_physical_presence;

static TPMVersion TPM_version;

+static u32 tpm20_pcr_selection_size;
+static struct tpml_pcr_selection *tpm20_pcr_selection;
+
 static struct tcpa_descriptor_rev2 *
 find_tcpa_by_rsdp(struct rsdp_descriptor *rsdp)
 {
@@ -669,6 +673,51 @@ err_exit:
 }

static int
+tpm20_getcapability(u32 capability, u32 property, u32 count,
+                    struct tpm_rsp_header *rsp, u32 rsize)
+{
+    struct tpm2_req_getcapability trg = {
+        .hdr.tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
+        .hdr.totlen = cpu_to_be32(sizeof(trg)),
+        .hdr.ordinal = cpu_to_be32(TPM2_CC_GetCapability),
+        .capability = cpu_to_be32(capability),
+        .property = cpu_to_be32(property),
+        .propertycount = cpu_to_be32(count),
+    };
+
+    u32 resp_size = rsize;
+    int ret = tpmhw_transmit(0, &trg.hdr, rsp, &resp_size,
+                             TPM_DURATION_TYPE_SHORT);
+    ret = (ret ||
+           rsize < be32_to_cpu(rsp->totlen)) ? -1 : be32_to_cpu(rsp->errcode);
+
+    dprintf(DEBUG_tcg, "TCGBIOS: Return value from sending TPM2_CC_GetCapability = 0x%08x\n",
+            ret);
+
+    return ret;
+}
+
+static int
+tpm20_get_pcrbanks(void)
+{
+    u8 buffer[128];
+    struct tpm2_res_getcapability *trg =
+      (struct tpm2_res_getcapability *)&buffer;
+
+    int ret = tpm20_getcapability(TPM2_CAP_PCRS, 0, 8, &trg->hdr,
+                                  sizeof(buffer));
+    if (ret)
+        return ret;
+
+    tpm20_pcr_selection_size = be32_to_cpu(trg->hdr.totlen) -
+                               offsetof(struct tpm2_res_getcapability, data);
+    tpm20_pcr_selection = malloc_high(tpm20_pcr_selection_size);
+    memcpy(tpm20_pcr_selection, &trg->data, tpm20_pcr_selection_size);
+
+    return 0;
+}
+
+static int
 tpm20_startup(void)
 {
     tpm20_set_timeouts();
@@ -701,6 +750,10 @@ tpm20_startup(void)
     if (ret)
         goto err_exit;

+    ret = tpm20_get_pcrbanks();
+    if (ret)
+        goto err_exit;
+
     return 0;

err_exit: