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authorDenis Kenzior <denkenz@gmail.com>2018-10-09 17:49:28 +0100
committerJames Morris <james.morris@microsoft.com>2018-10-26 09:30:47 +0100
commite73d170f6c77e7006b48c5e9c325fe520f6012ca (patch)
treecbff5f6905bdcb06e4dc497975736633fc91c507 /crypto
parente08e6891231f5fae82a6ffb4affdfa2ced8c1a77 (diff)
downloadlinux-stericsson-e73d170f6c77e7006b48c5e9c325fe520f6012ca.tar.gz
KEYS: asym_tpm: Implement tpm_sign [ver #2]
Signed-off-by: Denis Kenzior <denkenz@gmail.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>
Diffstat (limited to 'crypto')
-rw-r--r--crypto/asymmetric_keys/asym_tpm.c87
1 files changed, 87 insertions, 0 deletions
diff --git a/crypto/asymmetric_keys/asym_tpm.c b/crypto/asymmetric_keys/asym_tpm.c
index a38ba375675e..a5a5f913a74f 100644
--- a/crypto/asymmetric_keys/asym_tpm.c
+++ b/crypto/asymmetric_keys/asym_tpm.c
@@ -20,9 +20,11 @@
#define TPM_ORD_FLUSHSPECIFIC 186
#define TPM_ORD_LOADKEY2 65
#define TPM_ORD_UNBIND 30
+#define TPM_ORD_SIGN 60
#define TPM_LOADKEY2_SIZE 59
#define TPM_FLUSHSPECIFIC_SIZE 18
#define TPM_UNBIND_SIZE 63
+#define TPM_SIGN_SIZE 63
#define TPM_RT_KEY 0x00000001
@@ -190,6 +192,91 @@ static int tpm_unbind(struct tpm_buf *tb,
}
/*
+ * Sign a blob provided by userspace (that has had the hash function applied)
+ * using a specific key handle. The handle is assumed to have been previously
+ * loaded by e.g. LoadKey2.
+ *
+ * Note that the key signature scheme of the used key should be set to
+ * TPM_SS_RSASSAPKCS1v15_DER. This allows the hashed input to be of any size
+ * up to key_length_in_bytes - 11 and not be limited to size 20 like the
+ * TPM_SS_RSASSAPKCS1v15_SHA1 signature scheme.
+ */
+static int tpm_sign(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_SIGN);
+ 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_SIGN_SIZE + bloblen);
+ store32(tb, TPM_ORD_SIGN);
+ 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(datalen, outlen));
+
+ 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