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KEYS: asym_tpm: Implement tpm_unbind [ver #2]

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Signed-off-by: Denis Kenzior <denkenz@gmail.com>
Reviewed-by: James Morris <james.morris@microsoft.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: James Morris <james.morris@microsoft.com>
This commit is contained in:
Denis Kenzior 2018-10-09 17:49:05 +01:00 committed by James Morris
parent 0c36264aa1
commit f884fe5a15
1 changed files with 82 additions and 0 deletions
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82
crypto/asymmetric_keys/asym_tpm.c
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@ -18,8 +18,10 @@
#define TPM_ORD_FLUSHSPECIFIC 186
#define TPM_ORD_LOADKEY2 65
#define TPM_ORD_UNBIND 30
#define TPM_LOADKEY2_SIZE 59
#define TPM_FLUSHSPECIFIC_SIZE 18
#define TPM_UNBIND_SIZE 63
#define TPM_RT_KEY 0x00000001
@ -106,6 +108,86 @@ static int tpm_flushspecific(struct tpm_buf *tb, uint32_t handle)
return trusted_tpm_send(tb->data, MAX_BUF_SIZE);
}
/*
* Decrypt a blob provided by userspace using a specific key handle.
* The handle is a well known handle or previously loaded by e.g. LoadKey2
*/
static int tpm_unbind(struct tpm_buf *tb,
uint32_t keyhandle, unsigned char *keyauth,
const unsigned char *blob, uint32_t bloblen,
void *out, uint32_t outlen)
{
unsigned char nonceodd[TPM_NONCE_SIZE];
unsigned char enonce[TPM_NONCE_SIZE];
unsigned char authdata[SHA1_DIGEST_SIZE];
uint32_t authhandle = 0;
unsigned char cont = 0;
uint32_t ordinal;
uint32_t datalen;
int ret;
ordinal = htonl(TPM_ORD_UNBIND);
datalen = htonl(bloblen);
/* session for loading the key */
ret = oiap(tb, &authhandle, enonce);
if (ret < 0) {
pr_info("oiap failed (%d)\n", ret);
return ret;
}
/* generate odd nonce */
ret = tpm_get_random(NULL, nonceodd, TPM_NONCE_SIZE);
if (ret < 0) {
pr_info("tpm_get_random failed (%d)\n", ret);
return ret;
}
/* calculate authorization HMAC value */
ret = TSS_authhmac(authdata, keyauth, SHA1_DIGEST_SIZE, enonce,
nonceodd, cont, sizeof(uint32_t), &ordinal,
sizeof(uint32_t), &datalen,
bloblen, blob, 0, 0);
if (ret < 0)
return ret;
/* build the request buffer */
INIT_BUF(tb);
store16(tb, TPM_TAG_RQU_AUTH1_COMMAND);
store32(tb, TPM_UNBIND_SIZE + bloblen);
store32(tb, TPM_ORD_UNBIND);
store32(tb, keyhandle);
store32(tb, bloblen);
storebytes(tb, blob, bloblen);
store32(tb, authhandle);
storebytes(tb, nonceodd, TPM_NONCE_SIZE);
store8(tb, cont);
storebytes(tb, authdata, SHA1_DIGEST_SIZE);
ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
if (ret < 0) {
pr_info("authhmac failed (%d)\n", ret);
return ret;
}
datalen = LOAD32(tb->data, TPM_DATA_OFFSET);
ret = TSS_checkhmac1(tb->data, ordinal, nonceodd,
keyauth, SHA1_DIGEST_SIZE,
sizeof(uint32_t), TPM_DATA_OFFSET,
datalen, TPM_DATA_OFFSET + sizeof(uint32_t),
0, 0);
if (ret < 0) {
pr_info("TSS_checkhmac1 failed (%d)\n", ret);
return ret;
}
memcpy(out, tb->data + TPM_DATA_OFFSET + sizeof(uint32_t),
min(outlen, datalen));
return datalen;
}
/*
* Maximum buffer size for the BER/DER encoded public key. The public key
* is of the form SEQUENCE { INTEGER n, INTEGER e } where n is a maximum 2048