Milestone 5: deliver embedded RDP sessions and lifecycle hardening

third_party/FreeRDP/channels/rdpear/common/rdpear_asn1.c

@@ -0,0 +1,104 @@
+/**
+ * FreeRDP: A Remote Desktop Protocol Implementation
+ * ASN1 routines for RDPEAR
+ *
+ * Copyright 2024 David Fort <contact@hardening-consulting.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <rdpear-common/rdpear_asn1.h>
+#include <winpr/asn1.h>
+
+wStream* rdpear_enc_Checksum(UINT32 cksumtype, krb5_checksum* csum)
+{
+	/**
+	 * Checksum        ::= SEQUENCE {
+	 *   cksumtype       [0] Int32,
+	 *   checksum        [1] OCTET STRING
+	 * }
+	 */
+	wStream* ret = nullptr;
+	WinPrAsn1Encoder* enc = WinPrAsn1Encoder_New(WINPR_ASN1_DER);
+	if (!enc)
+		return nullptr;
+
+	if (!WinPrAsn1EncSeqContainer(enc))
+		goto out;
+
+	if (!WinPrAsn1EncContextualInteger(enc, 0, (WinPrAsn1_INTEGER)cksumtype))
+		goto out;
+
+	WinPrAsn1_OctetString octets;
+	octets.data = (BYTE*)csum->contents;
+	octets.len = csum->length;
+	if (!WinPrAsn1EncContextualOctetString(enc, 1, &octets) || !WinPrAsn1EncEndContainer(enc))
+		goto out;
+
+	ret = Stream_New(nullptr, 1024);
+	if (!ret)
+		goto out;
+
+	if (!WinPrAsn1EncToStream(enc, ret))
+	{
+		Stream_Free(ret, TRUE);
+		ret = nullptr;
+		goto out;
+	}
+
+out:
+	WinPrAsn1Encoder_Free(&enc);
+	return ret;
+}
+
+wStream* rdpear_enc_EncryptedData(UINT32 encType, krb5_data* payload)
+{
+	/**
+	 * EncryptedData   ::= SEQUENCE {
+	 *   etype   [0] Int32 -- EncryptionType --,
+	 *   kvno    [1] UInt32 OPTIONAL,
+	 *   cipher  [2] OCTET STRING -- ciphertext
+	 *	}
+	 */
+	wStream* ret = nullptr;
+	WinPrAsn1Encoder* enc = WinPrAsn1Encoder_New(WINPR_ASN1_DER);
+	if (!enc)
+		return nullptr;
+
+	if (!WinPrAsn1EncSeqContainer(enc))
+		goto out;
+
+	if (!WinPrAsn1EncContextualInteger(enc, 0, (WinPrAsn1_INTEGER)encType))
+		goto out;
+
+	WinPrAsn1_OctetString octets;
+	octets.data = (BYTE*)payload->data;
+	octets.len = payload->length;
+	if (!WinPrAsn1EncContextualOctetString(enc, 2, &octets) || !WinPrAsn1EncEndContainer(enc))
+		goto out;
+
+	ret = Stream_New(nullptr, 1024);
+	if (!ret)
+		goto out;
+
+	if (!WinPrAsn1EncToStream(enc, ret))
+	{
+		Stream_Free(ret, TRUE);
+		ret = nullptr;
+		goto out;
+	}
+
+out:
+	WinPrAsn1Encoder_Free(&enc);
+	return ret;
+}