KEYS: asym_tpm: Implement tpm_unbind [ver #2]

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>

diff --git a/crypto/asymmetric_keys/asym_tpm.c b/crypto/asymmetric_keys/asym_tpm.c
index 6a2d330..e893b52 100644 (file)
--- a/crypto/asymmetric_keys/asym_tpm.c
+++ b/crypto/asymmetric_keys/asym_tpm.c
@@ -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
 
@@ -107,6 +109,86 @@ static int tpm_flushspecific(struct tpm_buf *tb, uint32_t handle)
 }
 
 /*
+ * 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
  * bit key and e is usually 65537