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store: implemented tss2 scheme for loading FAPI keys
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gotthardp committed Oct 29, 2023
1 parent 0332e46 commit 77a20f7
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8 changes: 8 additions & 0 deletions Makefile.am
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Expand Up @@ -47,6 +47,11 @@ endif

tpm2_la_CFLAGS = $(TSS2_ESYS_CFLAGS) $(TSS2_TCTILDR_CFLAGS) $(COMMON_CFLAGS) $(CODE_COVERAGE_CFLAGS)
tpm2_la_LIBADD = $(TSS2_ESYS_LIBS) $(TSS2_TCTILDR_LIBS) $(LIBS) $(CODE_COVERAGE_LIBS)
if TSS2_FAPI
tpm2_la_SOURCES += src/tpm2-provider-store-tss2.c
tpm2_la_CFLAGS += $(TSS2_FAPI_CFLAGS)
tpm2_la_LIBADD += $(TSS2_FAPI_LIBS)
endif
if TSS2_RC
tpm2_la_LIBADD += $(TSS2_RC_LIBS)
endif
Expand Down Expand Up @@ -115,6 +120,9 @@ TESTS_SHELL += test/cipher_aes128_ecb.sh \
test/cipher_aes256_nopad.sh \
test/cipher_camellia128.sh
endif
if TSS2_FAPI
TESTS_SHELL += test/rsa_fapi_sign.sh
endif

TEST_EXTENSIONS = .sh
SH_LOG_COMPILER = $(srcdir)/test/run
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6 changes: 3 additions & 3 deletions README.md
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Expand Up @@ -146,9 +146,9 @@ and
[OSSL_DECODER](https://www.openssl.org/docs/manmaster/man3/OSSL_DECODER.html) API
to load (TPM2_Load) a private key from a previously generated file, as well as
persistent keys generated with the
[tpm2-tools](https://github.com/tpm2-software/tpm2-tools). Both the hexadecimal
key `handle` as well as the serialized `object` file may be used. These URI
prefixes may be used with any openssl command.
[tpm2-tools](https://github.com/tpm2-software/tpm2-tools). The hexadecimal key
`handle`, the serialized `object` file as well as the `tss2` metadata path may
be used. These URI prefixes may be used with any openssl command.

The corresponding public key can be stored using the
[`openssl pkey`](https://www.openssl.org/docs/manmaster/man1/openssl-pkey.html)
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4 changes: 3 additions & 1 deletion docs/CHANGELOG.md
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Expand Up @@ -5,7 +5,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)

## [1.3.0] - 2023-xx-yy
### Added
- Added support for RSA-OAEP decryption
- Implemented loading keys from the FAPI metadata store using the `tss2:` prefix,
followed by the key path, e.g. `tss2:HS/SRK/testkey`.
- Added support for RSA-OAEP decryption.

## [1.2.0] - 2023-10-14
### Added
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15 changes: 15 additions & 0 deletions docs/keys.md
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Expand Up @@ -167,6 +167,7 @@ loaders:
* **handle**, to load persistent keys, or data (public keys or certificates)
from NV indices;
* **object**, to load serialized object representing a persistent handle.
* **tss2**, to load persistent or transient objects from the FAPI metadata store.

These are used by the
[OSSL_STORE](https://www.openssl.org/docs/manmaster/man7/ossl_store.html)
Expand Down Expand Up @@ -246,3 +247,17 @@ To load a persistent key using the serialized object, specify the prefix
```
openssl rsa -provider tpm2 -modulus -noout -in object:ak_rsa.obj
```

### Using FAPI Metadata Store

The `tss2_createkey` creates a key inside the TPM and stores it in the FAPI
metadata store:
```
tss2_createkey --path=HS/SRK/testkey --type="noDa,sign"
```

To load a key from the FAPI metadata store, specify the prefix `tss2:` and then
the object path:
```
openssl rsa -provider tpm2 -modulus -noout -in tss2:HS/SRK/testkey
```
309 changes: 309 additions & 0 deletions src/tpm2-provider-store-tss2.c
Original file line number Diff line number Diff line change
@@ -0,0 +1,309 @@
/* SPDX-License-Identifier: BSD-3-Clause */

#include <string.h>

#include <openssl/core_dispatch.h>
#include <openssl/core_names.h>
#include <openssl/core_object.h>
#include <openssl/params.h>

#include <tss2/tss2_fapi.h>
#include <tss2/tss2_mu.h>
#include "tpm2-provider-pkey.h"

typedef struct tpm2_store_ctx_st TPM2_STORE_CTX;

struct tpm2_store_ctx_st {
const OSSL_CORE_HANDLE *core;
ESYS_CONTEXT *esys_ctx;
TPM2_CAPABILITY capability;
char *path;
FAPI_CONTEXT *fapi_ctx;
int load_done;
};

static OSSL_FUNC_store_open_fn tpm2_store_open;
static OSSL_FUNC_store_settable_ctx_params_fn tpm2_store_settable_params;
static OSSL_FUNC_store_set_ctx_params_fn tpm2_store_set_params;
static OSSL_FUNC_store_load_fn tpm2_store_load;
static OSSL_FUNC_store_eof_fn tpm2_store_eof;
static OSSL_FUNC_store_close_fn tpm2_store_close;

static void *
tpm2_store_open(void *provctx, const char *uri)
{
TPM2_PROVIDER_CTX *cprov = provctx;
TPM2_STORE_CTX *sctx;
TSS2_RC r;

if (!uri || strncmp(uri, "tss2:", 5))
return NULL;

DBG("STORE/TSS2 OPEN %s\n", uri+5);
if ((sctx = OPENSSL_zalloc(sizeof(TPM2_STORE_CTX))) == NULL)
return NULL;

sctx->core = cprov->core;
sctx->esys_ctx = cprov->esys_ctx;
sctx->capability = cprov->capability;

if (!(sctx->path = strdup(uri+5)))
goto error1;

r = Fapi_Initialize(&sctx->fapi_ctx, NULL);
TPM2_CHECK_RC(sctx->core, r, TPM2_ERR_CANNOT_LOAD_KEY, goto error2);

return sctx;
error2:
free(sctx->path);
error1:
OPENSSL_clear_free(sctx, sizeof(TPM2_STORE_CTX));
return NULL;
}

static const OSSL_PARAM *
tpm2_store_settable_params(void *provctx)
{
static const OSSL_PARAM known_settable_ctx_params[] = {
OSSL_PARAM_END
};
return known_settable_ctx_params;
}

static int
tpm2_store_set_params(void *loaderctx, const OSSL_PARAM params[])
{
TRACE_PARAMS("STORE/TSS2 SET_PARAMS", params);
return 1;
}

static int
tpm2_store_load_pkey(TPM2_STORE_CTX *sctx, ESYS_TR object,
OSSL_CALLBACK *object_cb, void *object_cbarg)
{
TPM2B_PUBLIC *out_public = NULL;
TPM2_PKEY *pkey = NULL;
TSS2_RC r;
int ret = 0;

DBG("STORE/TSS2 LOAD pkey\n");
pkey = OPENSSL_zalloc(sizeof(TPM2_PKEY));
if (pkey == NULL)
return 0;

pkey->core = sctx->core;
pkey->esys_ctx = sctx->esys_ctx;
pkey->capability = sctx->capability;
pkey->object = object;

r = Esys_ReadPublic(sctx->esys_ctx, object,
ESYS_TR_NONE, ESYS_TR_NONE, ESYS_TR_NONE,
&out_public, NULL, NULL);
TPM2_CHECK_RC(sctx->core, r, TPM2_ERR_CANNOT_LOAD_KEY, goto final);

pkey->data.pub = *out_public;
pkey->data.privatetype = KEY_TYPE_HANDLE;
Esys_TR_GetTpmHandle(sctx->esys_ctx, object, &pkey->data.handle);
pkey->data.emptyAuth = 1;

free(out_public);

OSSL_PARAM params[4];
int object_type = OSSL_OBJECT_PKEY;
const char *keytype;

params[0] = OSSL_PARAM_construct_int(OSSL_OBJECT_PARAM_TYPE, &object_type);

if ((keytype = tpm2_openssl_type(&pkey->data)) == NULL) {
TPM2_ERROR_raise(sctx->core, TPM2_ERR_UNKNOWN_ALGORITHM);
goto final;
}
DBG("STORE/TSS2 LOAD found %s\n", keytype);
params[1] = OSSL_PARAM_construct_utf8_string(OSSL_OBJECT_PARAM_DATA_TYPE,
(char *)keytype, 0);
/* The address of the key becomes the octet string */
params[2] = OSSL_PARAM_construct_octet_string(OSSL_OBJECT_PARAM_REFERENCE,
&pkey, sizeof(pkey));
params[3] = OSSL_PARAM_construct_end();

ret = object_cb(params, object_cbarg);
final:
OPENSSL_clear_free(pkey, sizeof(TPM2_PKEY));
return ret;
}

static int
tpm2_store_load_index(TPM2_STORE_CTX *sctx, ESYS_TR object,
OSSL_CALLBACK *object_cb, void *object_cbarg)
{
TPM2B_NV_PUBLIC *metadata = NULL;
uint16_t read_len, read_max, data_len = 0;
unsigned char *data = NULL;
BIO *bufio;
TSS2_RC r;
int ret = 0;

r = Esys_NV_ReadPublic(sctx->esys_ctx, object,
ESYS_TR_NONE, ESYS_TR_NONE, ESYS_TR_NONE,
&metadata, NULL);
TPM2_CHECK_RC(sctx->core, r, TPM2_ERR_CANNOT_LOAD_KEY, goto final);

read_len = metadata->nvPublic.dataSize;
read_max = tpm2_max_nvindex_buffer(sctx->capability.properties);
DBG("STORE/TSS2 LOAD index %u bytes (buffer %u bytes)\n", read_len, read_max);

if ((data = malloc(read_len)) == NULL)
goto final;

while (read_len > 0) {
uint16_t bytes_to_read = read_len < read_max ? read_len : read_max;
TPM2B_MAX_NV_BUFFER *buff = NULL;

r = Esys_NV_Read(sctx->esys_ctx, object, object,
ESYS_TR_PASSWORD, ESYS_TR_NONE, ESYS_TR_NONE,
bytes_to_read, data_len, &buff);
TPM2_CHECK_RC(sctx->core, r, TPM2_ERR_CANNOT_LOAD_KEY, goto final);

memcpy(data + data_len, buff->buffer, buff->size);
read_len -= buff->size;
data_len += buff->size;
free(buff);
}

OSSL_PARAM params[3];
int object_type = OSSL_OBJECT_UNKNOWN;
char *pem_name = NULL;
char *pem_header = NULL;
unsigned char *der_data = NULL;
long der_len;

if ((bufio = BIO_new_mem_buf(data, data_len)) == NULL)
goto final;

/* the ossl_store_handle_load_result() supports DER objects only */
if (PEM_read_bio(bufio, &pem_name, &pem_header, &der_data, &der_len) > 0) {
if (pem_name != NULL) {
DBG("STORE/TSS2 LOAD(PEM) %s %li bytes\n", pem_name, der_len);

if (!strcmp(pem_name, TSSPRIVKEY_PEM_STRING))
object_type = OSSL_OBJECT_PKEY;
else if (!strcmp(pem_name, PEM_STRING_X509))
object_type = OSSL_OBJECT_CERT;
else if (!strcmp(pem_name, PEM_STRING_X509_CRL))
object_type = OSSL_OBJECT_CRL;
}

/* pass the data to ossl_store_handle_load_result(),
which will call the TPM2_PKEY decoder or read the certificate */
params[0] = OSSL_PARAM_construct_int(OSSL_OBJECT_PARAM_TYPE, &object_type);

params[1] = OSSL_PARAM_construct_octet_string(OSSL_OBJECT_PARAM_DATA,
der_data, der_len);
} else {
params[0] = OSSL_PARAM_construct_int(OSSL_OBJECT_PARAM_TYPE, &object_type);

params[1] = OSSL_PARAM_construct_octet_string(OSSL_OBJECT_PARAM_DATA,
data, data_len);
}

params[2] = OSSL_PARAM_construct_end();

ret = object_cb(params, object_cbarg);

OPENSSL_free(pem_name);
OPENSSL_free(pem_header);
OPENSSL_free(der_data);
BIO_free(bufio);
final:
free(data);
free(metadata);
return ret;
}

static int
tpm2_store_load(void *ctx,
OSSL_CALLBACK *object_cb, void *object_cbarg,
OSSL_PASSPHRASE_CALLBACK *pw_cb, void *pw_cbarg)
{
TPM2_STORE_CTX *sctx = ctx;
uint8_t type;
uint8_t *data = NULL;
size_t length;
TPMS_CONTEXT blob;
ESYS_TR object;
TSS2_RC r;
int ret = 0;

DBG("STORE/TSS2 LOAD\n");
r = Fapi_GetEsysBlob(sctx->fapi_ctx, sctx->path, &type, &data, &length);
sctx->load_done = 1;
TPM2_CHECK_RC(sctx->core, r, TPM2_ERR_CANNOT_LOAD_KEY, return 0);

switch(type) {
case FAPI_ESYSBLOB_DESERIALIZE:
r = Esys_TR_Deserialize(sctx->esys_ctx, data, length, &object);
TPM2_CHECK_RC(sctx->core, r, TPM2_ERR_CANNOT_LOAD_KEY, goto error1);
break;
case FAPI_ESYSBLOB_CONTEXTLOAD:
r = Tss2_MU_TPMS_CONTEXT_Unmarshal(data, length, NULL, &blob);
TPM2_CHECK_RC(sctx->core, r, TPM2_ERR_CANNOT_LOAD_KEY, goto error1);

r = Esys_ContextLoad(sctx->esys_ctx, &blob, &object);
TPM2_CHECK_RC(sctx->core, r, TPM2_ERR_CANNOT_LOAD_KEY, goto error1);
break;
default:
TPM2_ERROR_raise(sctx->core, TPM2_ERR_CANNOT_LOAD_KEY);
goto error1;
}
Fapi_Free(data);

if (!strncmp(sctx->path, "/nv/", 4)) {
ret = tpm2_store_load_index(sctx, object, object_cb, object_cbarg);
Esys_TR_Close(sctx->esys_ctx, &object);
} else {
ret = tpm2_store_load_pkey(sctx, object, object_cb, object_cbarg);
if (!ret)
Esys_TR_Close(sctx->esys_ctx, &object);
}

return ret;
error2:
Esys_TR_Close(sctx->esys_ctx, &object);
error1:
Fapi_Free(data);
return 0;
}

static int
tpm2_store_eof(void *ctx)
{
TPM2_STORE_CTX *sctx = ctx;
return sctx->load_done;
}

static int
tpm2_store_close(void *ctx)
{
TPM2_STORE_CTX *sctx = ctx;

if (sctx == NULL)
return 0;

DBG("STORE/TSS2 CLOSE\n");
Fapi_Finalize(&sctx->fapi_ctx);
free(sctx->path);

OPENSSL_clear_free(ctx, sizeof(TPM2_STORE_CTX));
return 1;
}

const OSSL_DISPATCH tpm2_tss2_store_functions[] = {
{ OSSL_FUNC_STORE_OPEN, (void(*)(void))tpm2_store_open },
{ OSSL_FUNC_STORE_SETTABLE_CTX_PARAMS, (void(*)(void))tpm2_store_settable_params },
{ OSSL_FUNC_STORE_SET_CTX_PARAMS, (void(*)(void))tpm2_store_set_params },
{ OSSL_FUNC_STORE_LOAD, (void(*)(void))tpm2_store_load },
{ OSSL_FUNC_STORE_EOF, (void(*)(void))tpm2_store_eof },
{ OSSL_FUNC_STORE_CLOSE, (void(*)(void))tpm2_store_close },
{ 0, NULL }
};

6 changes: 6 additions & 0 deletions src/tpm2-provider.c
Original file line number Diff line number Diff line change
Expand Up @@ -234,10 +234,16 @@ static const OSSL_ALGORITHM tpm2_decoders[] = {
};

extern const OSSL_DISPATCH tpm2_handle_store_functions[];
//#if WITH_TSS2_FAPI
//extern const OSSL_DISPATCH tpm2_tss2_store_functions[];
//#endif

static const OSSL_ALGORITHM tpm2_stores[] = {
{ "handle", TPM2_PROPS(store), tpm2_handle_store_functions },
{ "object", TPM2_PROPS(store), tpm2_handle_store_functions },
//#if WITH_TSS2_FAPI
// { "tss2", TPM2_PROPS(store), tpm2_tss2_store_functions },
//#endif
{ NULL, NULL, NULL }
};

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