[SeaBIOS] [PATCH 3/3] tpm: Extend tpm20_extend to support extending to multiple PCR banks
Stefan Berger
stefanb at linux.vnet.ibm.com
Tue Jul 19 19:41:56 CEST 2016
Extend the tpm20_extend function to support extending a hash to
multiple PCR banks. The sha1 hash that's being extended into the
sha256 bank for example, will be filled with zero-bytes to the
size of a sha256 hash.
Signed-off-by: Stefan Berger <stefanb at linux.vnet.ibm.com>
---
src/std/tcg.h | 14 +++++++--
src/tcgbios.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
2 files changed, 105 insertions(+), 8 deletions(-)
diff --git a/src/std/tcg.h b/src/std/tcg.h
index 1644684..9e4ef57 100644
--- a/src/std/tcg.h
+++ b/src/std/tcg.h
@@ -100,6 +100,10 @@ enum irq_ids {
#define EV_IPL_PARTITION_DATA 14
#define SHA1_BUFSIZE 20
+#define SHA256_BUFSIZE 32
+#define SHA384_BUFSIZE 48
+#define SHA512_BUFSIZE 64
+#define SM3_256_BUFSIZE 32
/* Input and Output blocks for the TCG BIOS commands */
@@ -381,6 +385,10 @@ struct tpm_res_sha1complete {
#define TPM2_RH_PLATFORM 0x4000000c
#define TPM2_ALG_SHA1 0x0004
+#define TPM2_ALG_SHA256 0x000b
+#define TPM2_ALG_SHA384 0x000c
+#define TPM2_ALG_SHA512 0x000d
+#define TPM2_ALG_SM3_256 0x0012
/* TPM 2 command tags */
#define TPM2_ST_NO_SESSIONS 0x8001
@@ -442,8 +450,8 @@ struct tpm2_req_hierarchychangeauth {
} PACKED;
struct tpm2_digest_value {
- u16 hashalg; /* TPM2_ALG_SHA1 */
- u8 sha1[SHA1_BUFSIZE];
+ u16 hashAlg; /* TPM2_ALG_SHA1 */
+ u8 hash[0]; /* size depends on hashAlg */
} PACKED;
struct tpm2_req_extend {
@@ -452,7 +460,7 @@ struct tpm2_req_extend {
u32 authblocksize;
struct tpm2_authblock authblock;
u32 count;
- struct tpm2_digest_value digest;
+ struct tpm2_digest_value digest[0];
} PACKED;
struct tpm2_req_clearcontrol {
diff --git a/src/tcgbios.c b/src/tcgbios.c
index 72ae3c6..acd0b71 100644
--- a/src/tcgbios.c
+++ b/src/tcgbios.c
@@ -446,11 +446,94 @@ tpm12_extend(u32 pcrindex, const u8 *digest)
return 0;
}
+static int
+tpm20_get_hash_buffersize(u16 hashAlg)
+{
+ switch (hashAlg) {
+ case TPM2_ALG_SHA1:
+ return SHA1_BUFSIZE;
+ case TPM2_ALG_SHA256:
+ return SHA256_BUFSIZE;
+ case TPM2_ALG_SHA384:
+ return SHA384_BUFSIZE;
+ case TPM2_ALG_SHA512:
+ return SHA512_BUFSIZE;
+ case TPM2_ALG_SM3_256:
+ return SM3_256_BUFSIZE;
+ default:
+ return -1;
+ }
+}
+
+/*
+ * Write the TPM2 PCR Extend 'body' containing the hashes. Follow
+ * the PCR bank configuration of the TPM.
+ *
+ * dest: destinatiobn buffer to write into; if NULL, nothing is written
+ * pcrindex: the PCR index
+ * hash: the hash value to write
+ * hashAlg: the hash alogorithm determining the size of the hash
+ * count: pointer to a counter for how many entries were writte
+ *
+ * Returns the number of bytes written into the buffer; -1 on fatal error
+ */
+static int
+tpm20_write_extend_body(char *dest, u32 pcrindex, const u8 *hash,
+ u16 hashAlg, u32 *count)
+{
+ int offset = 0, hsize;
+ struct tpms_pcr_selection *sel = tpm20_pcr_selection->selections;
+ void *nsel, *end = (void *)tpm20_pcr_selection + tpm20_pcr_selection_size;
+ int hash_size = tpm20_get_hash_buffersize(hashAlg);
+
+ for (*count = 0;
+ *count < be32_to_cpu(tpm20_pcr_selection->count);
+ (*count)++) {
+ u8 sizeOfSelect = sel->sizeOfSelect;
+
+ nsel = (void *)sel +
+ offsetof(struct tpms_pcr_selection, pcrSelect) +
+ sizeOfSelect;
+ if (nsel > end)
+ break;
+
+ u8 idx = pcrindex >> 3;
+ u8 mask = (1 << (pcrindex & 7));
+ /* skip if PCR not used in this bank */
+ if (idx > sizeOfSelect || !(sel->pcrSelect[idx] & mask))
+ continue;
+
+ hsize = tpm20_get_hash_buffersize(be16_to_cpu(sel->hashAlg));
+ if (hsize < 0) {
+ dprintf(DEBUG_tcg, "TPM is using an unsupported hash: %d\n",
+ be16_to_cpu(sel->hashAlg));
+ return -1;
+ }
+
+ if (dest) {
+ struct tpm2_digest_value *v =
+ (struct tpm2_digest_value *)&dest[offset];
+ v->hashAlg = sel->hashAlg;
+ memset(v->hash, 0, hsize);
+ memcpy(v->hash, hash, hash_size);
+ }
+ offset += sizeof(sel->hashAlg) + hsize;
+ sel = nsel;
+ }
+
+ if (sel != end) {
+ dprintf(DEBUG_tcg, "Malformed pcr selection structure fron TPM\n");
+ return -1;
+ }
+
+ return offset;
+}
+
static int tpm20_extend(u32 pcrindex, const u8 *digest, u16 hashAlg)
{
struct tpm2_req_extend tmp_tre = {
.hdr.tag = cpu_to_be16(TPM2_ST_SESSIONS),
- .hdr.totlen = cpu_to_be32(sizeof(tmp_tre)),
+ .hdr.totlen = cpu_to_be32(0),
.hdr.ordinal = cpu_to_be32(TPM2_CC_PCR_Extend),
.pcrindex = cpu_to_be32(pcrindex),
.authblocksize = cpu_to_be32(sizeof(tmp_tre.authblock)),
@@ -461,14 +544,20 @@ static int tpm20_extend(u32 pcrindex, const u8 *digest, u16 hashAlg)
.pwdsize = cpu_to_be16(0),
},
};
- u32 count = 1;
- u8 buffer[sizeof(tmp_tre) + sizeof(struct tpm2_digest_value)];
+ u32 count = 0;
+ int bsize = tpm20_write_extend_body(NULL, pcrindex, digest, hashAlg,
+ &count);
+ if (bsize < 0)
+ return bsize;
+
+ u8 buffer[sizeof(tmp_tre) + bsize];
struct tpm2_req_extend *tre = (struct tpm2_req_extend *)buffer;
memcpy(tre, &tmp_tre, sizeof(tmp_tre));
+ tre->hdr.totlen = cpu_to_be32(sizeof(buffer));
+ tpm20_write_extend_body((char *)&tre->digest, pcrindex, digest, hashAlg,
+ &count);
tre->count = cpu_to_be32(count);
- tre->digest.hashalg = cpu_to_be16(hashAlg);
- memcpy(tre->digest.sha1, digest, sizeof(tmp_tre.digest.sha1));
struct tpm_rsp_header rsp;
u32 resp_length = sizeof(rsp);
--
2.5.5
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