Skip to content

Commit

Permalink
TPM based root of trust using NV index.
Browse files Browse the repository at this point in the history
  • Loading branch information
@dgarske
dgarske committed Aug 15, 2023
1 parent f2012c3 commit 185ab61
Show file tree
Hide file tree
Showing 2 changed files with 73 additions and 22 deletions.
87 changes: 69 additions & 18 deletions src/image.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -121,20 +121,21 @@ static void wolfBoot_verify_signature(uint8_t key_slot,
{
int ret, verify_res = 0;
uint8_t *pubkey = keystore_get_buffer(key_slot);
int point_sz = keystore_get_size(key_slot)/2;
#ifdef WOLFBOOT_TPM
int pubkey_sz = keystore_get_size(key_slot);
int point_sz = pubkey_sz/2;
#if defined(WOLFBOOT_TPM) && !defined(WOLFBOOT_TPM_KEYSTORE)
WOLFTPM2_KEY tpmKey;
#else
ecc_key ecc;
mp_int r, s;
#endif

if (pubkey == NULL || point_sz <= 0)
if (pubkey == NULL || pubkey_sz <= 0) {
return;
}

#ifdef WOLFBOOT_TPM
/* TODO: Check ECC Root of Trust in TPM */

#if defined(WOLFBOOT_TPM) && !defined(WOLFBOOT_TPM_KEYSTORE)
/* Use TPM for ECC verify */
/* Load public key into TPM */
memset(&tpmKey, 0, sizeof(tpmKey));
ret = wolfTPM2_LoadEccPublicKey(&wolftpm_dev, &tpmKey,
Expand Down Expand Up @@ -276,25 +277,24 @@ static void wolfBoot_verify_signature(uint8_t key_slot,
{
int ret;
uint8_t output[IMAGE_SIGNATURE_SIZE];
int output_sz = sizeof(output);
int output_sz = (int)sizeof(output);
uint8_t* digest_out = NULL;
uint8_t *pubkey = keystore_get_buffer(key_slot);
int pubkey_sz = keystore_get_size(key_slot);
word32 inOutIdx = 0;
#ifdef WOLFBOOT_TPM
#if defined(WOLFBOOT_TPM) && !defined(WOLFBOOT_TPM_KEYSTORE)
WOLFTPM2_KEY tpmKey;
const byte *n = NULL, *e = NULL;
word32 nSz = 0, eSz = 0;
#else
struct RsaKey rsa;
#endif

if ((pubkey_sz < 0) || (pubkey == NULL))
if (pubkey == NULL || pubkey_sz < 0) {
return;
}

#ifdef WOLFBOOT_TPM
/* TODO: Check RSA Root of Trust in TPM */

#if defined(WOLFBOOT_TPM) && !defined(WOLFBOOT_TPM_KEYSTORE)
/* Extract DER RSA key struct */
memset(&tpmKey, 0, sizeof(tpmKey));
ret = wc_RsaPublicKeyDecode_ex(pubkey, &inOutIdx, pubkey_sz,
Expand Down Expand Up @@ -365,8 +365,9 @@ static void wolfBoot_verify_signature(uint8_t key_slot,
ret = RsaDecodeSignature(&digest_out, ret);
}
#endif
if (ret == WOLFBOOT_SHA_DIGEST_SIZE && img && digest_out)
if (ret == WOLFBOOT_SHA_DIGEST_SIZE && img && digest_out) {
RSA_VERIFY_HASH(img, digest_out);
}
}
#endif /* WOLFBOOT_SIGN_RSA2048 || WOLFBOOT_SIGN_3072 || \
* WOLFBOOT_SIGN_RSA4096 */
Expand Down Expand Up @@ -642,7 +643,8 @@ static void key_sha3_384(uint8_t key_slot, uint8_t *hash)
#endif /* SHA3-384 */

#ifdef WOLFBOOT_TPM
#if defined(WOLFTPM_DEBUG_IO) || defined(WOLFBOOT_DEBUG_TPM)
#if defined(DEBUG_WOLFTPM) || defined(WOLFTPM_DEBUG_IO) || \
defined(WOLFBOOT_DEBUG_TPM)
#define LINE_LEN 16
static void wolfBoot_PrintBin(const byte* buffer, word32 length)
{
Expand Down Expand Up @@ -698,6 +700,14 @@ static int TPM2_IoCb(TPM2_CTX* ctx, const byte* txBuf, byte* rxBuf,
byte rxBuf[MAX_SPI_FRAMESIZE+TPM_TIS_HEADER_SZ];
int xferSz = TPM_TIS_HEADER_SZ + size;

#ifdef WOLFTPM_DEBUG_IO
wolfBoot_printf("TPM2_IoCb (Adv): Read %d, Addr %x, Size %d\n",
isRead ? 1 : 0, addr, size);
if (!isRead) {
wolfBoot_PrintBin(buf, size);
}
#endif

/* Build TPM header */
txBuf[1] = (addr>>16) & 0xFF;
txBuf[2] = (addr>>8) & 0xFF;
Expand All @@ -711,7 +721,7 @@ static int TPM2_IoCb(TPM2_CTX* ctx, const byte* txBuf, byte* rxBuf,
memcpy(&txBuf[TPM_TIS_HEADER_SZ], buf, size);
}
memset(rxBuf, 0, sizeof(rxBuf));
#endif
#endif /* WOLFTPM_ADV_IO */

#ifdef WOLFTPM_CHECK_WAIT_STATE /* Handle TIS wait states */
/* Send header - leave CS asserted */
Expand Down Expand Up @@ -751,11 +761,20 @@ static int TPM2_IoCb(TPM2_CTX* ctx, const byte* txBuf, byte* rxBuf,
}
#else /* Send Entire Message - no wait states */
ret = spi_xfer(SPI_CS_TPM, txBuf, rxBuf, xferSz, 0);
#endif

#ifdef WOLFTPM_DEBUG_IO
wolfBoot_printf("TPM2_IoCb: Ret %d, Sz %d\n", ret, xferSz);
wolfBoot_PrintBin(txBuf, xferSz);
wolfBoot_PrintBin(rxBuf, xferSz);
#endif
#endif /* !WOLFTPM_CHECK_WAIT_STATE */

#ifdef WOLFTPM_ADV_IO
if (isRead) {
memcpy(buf, &rxBuf[TPM_TIS_HEADER_SZ], size);
#ifdef WOLFTPM_DEBUG_IO
wolfBoot_PrintBin(buf, size);
#endif
}
#endif

Expand All @@ -764,8 +783,8 @@ static int TPM2_IoCb(TPM2_CTX* ctx, const byte* txBuf, byte* rxBuf,
#endif /* !ARCH_SIM */

#if defined(WOLFBOOT_TPM) && defined(WOLFBOOT_MEASURED_BOOT)
#define measure_boot(hash) measure_boot_at((hash), __LINE__)
static int measure_boot_at(uint8_t* hash, int line)
#define measure_boot(hash) wolfBoot_tpm2_extend((hash), __LINE__)
static int wolfBoot_tpm2_extend(uint8_t* hash, int line)
{
int rc;
PCR_Extend_In pcrExtend;
Expand Down Expand Up @@ -1178,12 +1197,44 @@ static int keyslot_id_by_sha(const uint8_t *hint)
/* Override global */
uint8_t digest[WOLFBOOT_SHA_DIGEST_SIZE];
#endif

#if defined(WOLFBOOT_TPM) && defined(WOLFBOOT_TPM_KEYSTORE)
/* use public key hash (hint) */
int rc;
WOLFTPM2_NV nv;
word32 digestSz = (word32)TPM2_GetHashDigestSize(WOLFBOOT_TPM_HASH_ALG);
XMEMSET(&nv, 0, sizeof(nv));
nv.handle.hndl = WOLFBOOT_TPM_KEYSTORE_NV_INDEX;

#if 0 /* TODO: Add auth */
nv.handle.auth.size = sizeof(authBuf);
XMEMCPY(nv.handle.auth.buffer, authBuf, sizeof(authBuf));
#endif

rc = wolfTPM2_NVReadAuth(&wolftpm_dev, &nv, WOLFBOOT_TPM_KEYSTORE_NV_INDEX,
digest, &digestSz, 0);
if (rc == 0 && memcmp(digest, hint, WOLFBOOT_SHA_DIGEST_SIZE) == 0) {
#ifdef DEBUG_WOLFTPM
wolfBoot_printf("TPM Root of Trust valid\n");
#endif
return 0;
}
else {
#ifdef DEBUG_WOLFTPM
wolfBoot_printf("TPM Root of Trust failed! %d (%s)\n",
rc, wolfTPM2_GetRCString(rc));
wolfBoot_printf("Expected Hash %d\n", WOLFBOOT_SHA_DIGEST_SIZE);
wolfBoot_PrintBin(hint, WOLFBOOT_SHA_DIGEST_SIZE);
#endif
}
#else
int id = 0;
for (id = 0; id < keystore_num_pubkeys(); id++) {
key_hash(id, digest);
if (memcmp(digest, hint, WOLFBOOT_SHA_DIGEST_SIZE) == 0)
return id;
}
#endif
return -1;
}
#endif
8 changes: 4 additions & 4 deletions tools/test.mk
View file
Original file line number Diff line number Diff line change
Expand Up @@ -924,9 +924,9 @@ test-size-all:
make keysclean
make test-size SIGN=ED25519 LIMIT=11398
make keysclean
make test-size SIGN=ECC256 LIMIT=22174
make test-size SIGN=ECC256 LIMIT=22266
make keysclean
make test-size SIGN=ECC256 NO_ASM=1 LIMIT=13650
make test-size SIGN=ECC256 NO_ASM=1 LIMIT=13702
make keysclean
make test-size SIGN=RSA2048 LIMIT=11182
make keysclean
Expand All @@ -936,9 +936,9 @@ test-size-all:
make keysclean
make test-size SIGN=RSA4096 NO_ASM=1 LIMIT=11462
make keysclean
make test-size SIGN=ECC384 LIMIT=17470
make test-size SIGN=ECC384 LIMIT=17562
make keysclean
make test-size SIGN=ECC384 NO_ASM=1 LIMIT=15082
make test-size SIGN=ECC384 NO_ASM=1 LIMIT=15172
make keysclean
make test-size SIGN=ED448 LIMIT=13414
make keysclean
Expand Down

0 comments on commit 185ab61

Please sign in to comment.