From: David Woodhouse <dwmw2@infradead.org>
Date: Tue, 11 May 2021 21:09:24 +0000 (+0100)
Subject: Support TLSv1.3 sign functions on SECP curves with TPMv2
X-Git-Tag: v8.20~201
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=4c225c0e68c7762d61bcdfc7392e2b638fc862b0;p=users%2Fdwmw2%2Fopenconnect.git

Support TLSv1.3 sign functions on SECP curves with TPMv2

For these curves at least, it basically already works.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
---

diff --git a/gnutls.h b/gnutls.h
index 378937e8..d6f75dc6 100644
--- a/gnutls.h
+++ b/gnutls.h
@@ -44,6 +44,7 @@ int tpm2_ec_sign_hash_fn(gnutls_privkey_t key, gnutls_sign_algorithm_t algo,
 			 const gnutls_datum_t *data, gnutls_datum_t *sig);
 int oc_pkcs1_pad(struct openconnect_info *vpninfo,
 		 unsigned char *buf, int size, const gnutls_datum_t *data);
+uint16_t tpm2_key_curve(struct openconnect_info *vpninfo, struct cert_info *certinfo);
 
 /* GnuTLS 3.6.0+ provides this. We have our own for older GnuTLS. There is
  * also _gnutls_encode_ber_rs_raw() in some older versions, but there were
diff --git a/gnutls_tpm2.c b/gnutls_tpm2.c
index a3ba3cdb..839e1b83 100644
--- a/gnutls_tpm2.c
+++ b/gnutls_tpm2.c
@@ -130,18 +130,34 @@ static int rsa_key_info(gnutls_privkey_t key, unsigned int flags, void *_certinf
 #if GNUTLS_VERSION_NUMBER >= 0x030400
 static int ec_key_info(gnutls_privkey_t key, unsigned int flags, void *_certinfo)
 {
+	struct cert_info *certinfo = _certinfo;
+	struct openconnect_info *vpninfo = certinfo->vpninfo;
+
 	if (flags & GNUTLS_PRIVKEY_INFO_PK_ALGO)
 		return GNUTLS_PK_EC;
 
 #ifdef GNUTLS_PRIVKEY_INFO_HAVE_SIGN_ALGO
 	if (flags & GNUTLS_PRIVKEY_INFO_HAVE_SIGN_ALGO) {
+		uint16_t tpm2_curve = tpm2_key_curve(vpninfo, certinfo);
 		gnutls_sign_algorithm_t algo = GNUTLS_FLAGS_TO_SIGN_ALGO(flags);
 		switch (algo) {
 		case GNUTLS_SIGN_ECDSA_SHA1:
 		case GNUTLS_SIGN_ECDSA_SHA256:
 			return 1;
 
+		case GNUTLS_SIGN_ECDSA_SECP256R1_SHA256:
+			return tpm2_curve == 0x0003; /* TPM2_ECC_NIST_P256 */
+
+		case GNUTLS_SIGN_ECDSA_SECP384R1_SHA384:
+			return tpm2_curve == 0x0004; /* TPM2_ECC_NIST_P384 */
+
+		case GNUTLS_SIGN_ECDSA_SECP521R1_SHA512:
+			return tpm2_curve == 0x0005; /* TPM2_ECC_NIST_P521 */
+
 		default:
+			vpn_progress(vpninfo, PRG_DEBUG,
+				     _("Not supporting EC sign algo %s\n"),
+				     gnutls_sign_get_name(algo));
 			return 0;
 		}
 	}
diff --git a/gnutls_tpm2_esys.c b/gnutls_tpm2_esys.c
index a57b843f..26e9b05d 100644
--- a/gnutls_tpm2_esys.c
+++ b/gnutls_tpm2_esys.c
@@ -603,6 +603,10 @@ int install_tpm2_key(struct openconnect_info *vpninfo, struct cert_info *certinf
 	return -EINVAL;
 }
 
+uint16_t tpm2_key_curve(struct openconnect_info *vpninfo, struct cert_info *certinfo)
+{
+	return certinfo->tpm2->pub.publicArea.parameters.eccDetail.curveID;
+}
 
 void release_tpm2_ctx(struct openconnect_info *vpninfo, struct cert_info *certinfo)
 {
diff --git a/gnutls_tpm2_ibm.c b/gnutls_tpm2_ibm.c
index fdf6fe56..16365dff 100644
--- a/gnutls_tpm2_ibm.c
+++ b/gnutls_tpm2_ibm.c
@@ -553,6 +553,10 @@ int install_tpm2_key(struct openconnect_info *vpninfo, struct cert_info *certinf
 	return -EINVAL;
 }
 
+uint16_t tpm2_key_curve(struct openconnect_info *vpninfo, struct cert_info *certinfo)
+{
+	return certinfo->tpm2->pub.publicArea.parameters.eccDetail.curveID;
+}
 
 void release_tpm2_ctx(struct openconnect_info *vpninfo, struct cert_info *certinfo)
 {