1 files changed, 468 insertions, 0 deletions
diff --git a/src/libipsec/esp_packet.c b/src/libipsec/esp_packet.c
new file mode 100644
index 000000000..bfcab95eb
--- /dev/null
+++ b/src/libipsec/esp_packet.c
@@ -0,0 +1,468 @@
+/*
+ * Copyright (C) 2012 Tobias Brunner
+ * Copyright (C) 2012 Giuliano Grassi
+ * Copyright (C) 2012 Ralf Sager
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+
+#include "esp_packet.h"
+
+#include <library.h>
+#include <debug.h>
+#include <crypto/crypters/crypter.h>
+#include <crypto/signers/signer.h>
+#include <bio/bio_reader.h>
+#include <bio/bio_writer.h>
+
+#include <netinet/in.h>
+
+typedef struct private_esp_packet_t private_esp_packet_t;
+
+/**
+ * Private additions to esp_packet_t.
+ */
+struct private_esp_packet_t {
+
+	/**
+	 * Public members
+	 */
+	esp_packet_t public;
+
+	/**
+	 * Raw ESP packet
+	 */
+	packet_t *packet;
+
+	/**
+	 * Payload of this packet
+	 */
+	ip_packet_t *payload;
+
+	/**
+	 * Next Header info (e.g. IPPROTO_IPIP)
+	 */
+	u_int8_t next_header;
+
+};
+
+/**
+ * Forward declaration for clone()
+ */
+static private_esp_packet_t *esp_packet_create_internal(packet_t *packet);
+
+METHOD(packet_t, set_source, void,
+	private_esp_packet_t *this, host_t *src)
+{
+	return this->packet->set_source(this->packet, src);
+}
+
+METHOD2(esp_packet_t, packet_t, get_source, host_t*,
+	private_esp_packet_t *this)
+{
+	return this->packet->get_source(this->packet);
+}
+
+METHOD(packet_t, set_destination, void,
+	private_esp_packet_t *this, host_t *dst)
+{
+	return this->packet->set_destination(this->packet, dst);
+}
+
+METHOD2(esp_packet_t, packet_t, get_destination, host_t*,
+	private_esp_packet_t *this)
+{
+	return this->packet->get_destination(this->packet);
+}
+
+METHOD(packet_t, get_data, chunk_t,
+	private_esp_packet_t *this)
+{
+	return this->packet->get_data(this->packet);
+}
+
+METHOD(packet_t, set_data, void,
+	private_esp_packet_t *this, chunk_t data)
+{
+	return this->packet->set_data(this->packet, data);
+}
+
+METHOD(packet_t, skip_bytes, void,
+	private_esp_packet_t *this, size_t bytes)
+{
+	return this->packet->skip_bytes(this->packet, bytes);
+}
+
+METHOD(packet_t, clone, packet_t*,
+	private_esp_packet_t *this)
+{
+	private_esp_packet_t *pkt;
+
+	pkt = esp_packet_create_internal(this->packet->clone(this->packet));
+	pkt->payload = this->payload ? this->payload->clone(this->payload) : NULL;
+	pkt->next_header = this->next_header;
+	return &pkt->public.packet;
+}
+
+METHOD(esp_packet_t, parse_header, bool,
+	private_esp_packet_t *this, u_int32_t *spi)
+{
+	bio_reader_t *reader;
+	u_int32_t seq;
+
+	reader = bio_reader_create(this->packet->get_data(this->packet));
+	if (!reader->read_uint32(reader, spi) ||
+		!reader->read_uint32(reader, &seq))
+	{
+		DBG1(DBG_ESP, "failed to parse ESP header: invalid length");
+		reader->destroy(reader);
+		return FALSE;
+	}
+	reader->destroy(reader);
+
+	DBG2(DBG_ESP, "parsed ESP header with SPI %.8x [seq %u]", *spi, seq);
+	*spi = htonl(*spi);
+	return TRUE;
+}
+
+/**
+ * Check padding as specified in RFC 4303
+ */
+static bool check_padding(chunk_t padding)
+{
+	size_t i;
+
+	for (i = 0; i < padding.len; ++i)
+	{
+		if (padding.ptr[i] != (u_int8_t)(i + 1))
+		{
+			return FALSE;
+		}
+	}
+	return TRUE;
+}
+
+/**
+ * Remove the padding from the payload and set the next header info
+ */
+static bool remove_padding(private_esp_packet_t *this, chunk_t plaintext)
+{
+	u_int8_t next_header, pad_length;
+	chunk_t padding, payload;
+	bio_reader_t *reader;
+
+	reader = bio_reader_create(plaintext);
+	if (!reader->read_uint8_end(reader, &next_header) ||
+		!reader->read_uint8_end(reader, &pad_length))
+	{
+		DBG1(DBG_ESP, "parsing ESP payload failed: invalid length");
+		goto failed;
+	}
+	if (!reader->read_data_end(reader, pad_length, &padding) ||
+		!check_padding(padding))
+	{
+		DBG1(DBG_ESP, "parsing ESP payload failed: invalid padding");
+		goto failed;
+	}
+	this->payload = ip_packet_create(reader->peek(reader));
+	reader->destroy(reader);
+	if (!this->payload)
+	{
+		DBG1(DBG_ESP, "parsing ESP payload failed: unsupported payload");
+		return FALSE;
+	}
+	this->next_header = next_header;
+	payload = this->payload->get_encoding(this->payload);
+
+	DBG3(DBG_ESP, "ESP payload:\n  payload %B\n  padding %B\n  "
+		 "padding length = %hhu, next header = %hhu", &payload, &padding,
+		 pad_length, this->next_header);
+	return TRUE;
+
+failed:
+	reader->destroy(reader);
+	chunk_free(&plaintext);
+	return FALSE;
+}
+
+METHOD(esp_packet_t, decrypt, status_t,
+	private_esp_packet_t *this, esp_context_t *esp_context)
+{
+	bio_reader_t *reader;
+	u_int32_t spi, seq;
+	chunk_t data, iv, icv, ciphertext, plaintext;
+	crypter_t *crypter;
+	signer_t *signer;
+
+	DESTROY_IF(this->payload);
+	this->payload = NULL;
+
+	data = this->packet->get_data(this->packet);
+	crypter = esp_context->get_crypter(esp_context);
+	signer = esp_context->get_signer(esp_context);
+
+	reader = bio_reader_create(data);
+	if (!reader->read_uint32(reader, &spi) ||
+		!reader->read_uint32(reader, &seq) ||
+		!reader->read_data(reader, crypter->get_iv_size(crypter), &iv) ||
+		!reader->read_data_end(reader, signer->get_block_size(signer), &icv) ||
+		reader->remaining(reader) % crypter->get_block_size(crypter))
+	{
+		DBG1(DBG_ESP, "ESP decryption failed: invalid length");
+		return PARSE_ERROR;
+	}
+	ciphertext = reader->peek(reader);
+	reader->destroy(reader);
+
+	if (!esp_context->verify_seqno(esp_context, seq))
+	{
+		DBG1(DBG_ESP, "ESP sequence number verification failed:\n  "
+			 "src %H, dst %H, SPI %.8x [seq %u]",
+			 get_source(this), get_destination(this), spi, seq);
+		return VERIFY_ERROR;
+	}
+	DBG3(DBG_ESP, "ESP decryption:\n  SPI %.8x [seq %u]\n  IV %B\n  "
+		 "encrypted %B\n  ICV %B", spi, seq, &iv, &ciphertext, &icv);
+
+	if (!signer->get_signature(signer, chunk_create(data.ptr, 8), NULL) ||
+		!signer->get_signature(signer, iv, NULL) ||
+		!signer->verify_signature(signer, ciphertext, icv))
+	{
+		DBG1(DBG_ESP, "ICV verification failed!");
+		return FAILED;
+	}
+	esp_context->set_authenticated_seqno(esp_context, seq);
+
+	if (!crypter->decrypt(crypter, ciphertext, iv, &plaintext))
+	{
+		DBG1(DBG_ESP, "ESP decryption failed");
+		return FAILED;
+	}
+
+	if (!remove_padding(this, plaintext))
+	{
+		return PARSE_ERROR;
+	}
+	return SUCCESS;
+}
+
+/**
+ * Generate the padding as specified in RFC4303
+ */
+static void generate_padding(chunk_t padding)
+{
+	size_t i;
+
+	for (i = 0; i < padding.len; ++i)
+	{
+		padding.ptr[i] = (u_int8_t)(i + 1);
+	}
+}
+
+METHOD(esp_packet_t, encrypt, status_t,
+	private_esp_packet_t *this, esp_context_t *esp_context, u_int32_t spi)
+{
+	chunk_t iv, icv, padding, payload, ciphertext, auth_data;
+	bio_writer_t *writer;
+	u_int32_t next_seqno;
+	size_t blocksize, plainlen;
+	crypter_t *crypter;
+	signer_t *signer;
+	rng_t *rng;
+
+	this->packet->set_data(this->packet, chunk_empty);
+
+	if (!esp_context->next_seqno(esp_context, &next_seqno))
+	{
+		DBG1(DBG_ESP, "ESP encapsulation failed: sequence numbers cycled");
+		return FAILED;
+	}
+
+	rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK);
+	if (!rng)
+	{
+		DBG1(DBG_ESP, "ESP encryption failed: could not find RNG");
+		return NOT_FOUND;
+	}
+	crypter = esp_context->get_crypter(esp_context);
+	signer = esp_context->get_signer(esp_context);
+
+	blocksize = crypter->get_block_size(crypter);
+	iv.len = crypter->get_iv_size(crypter);
+	icv.len = signer->get_block_size(signer);
+
+	/* plaintext = payload, padding, pad_length, next_header */
+	payload = this->payload ? this->payload->get_encoding(this->payload)
+							: chunk_empty;
+	plainlen = payload.len + 2;
+	padding.len = blocksize - (plainlen % blocksize);
+	plainlen += padding.len;
+
+	/* len = spi, seq, IV, plaintext, ICV */
+	writer = bio_writer_create(2 * sizeof(u_int32_t) + iv.len + plainlen +
+							   icv.len);
+	writer->write_uint32(writer, ntohl(spi));
+	writer->write_uint32(writer, next_seqno);
+
+	iv = writer->skip(writer, iv.len);
+	if (!rng->get_bytes(rng, iv.len, iv.ptr))
+	{
+		DBG1(DBG_ESP, "ESP encryption failed: could not generate IV");
+		writer->destroy(writer);
+		rng->destroy(rng);
+		return FAILED;
+	}
+	rng->destroy(rng);
+
+	/* plain-/ciphertext will start here */
+	ciphertext = writer->get_buf(writer);
+	ciphertext.ptr += ciphertext.len;
+	ciphertext.len = plainlen;
+
+	writer->write_data(writer, payload);
+
+	padding = writer->skip(writer, padding.len);
+	generate_padding(padding);
+
+	writer->write_uint8(writer, padding.len);
+	writer->write_uint8(writer, this->next_header);
+
+	DBG3(DBG_ESP, "ESP before encryption:\n  payload = %B\n  padding = %B\n  "
+		 "padding length = %hhu, next header = %hhu", &payload, &padding,
+		 (u_int8_t)padding.len, this->next_header);
+
+	/* encrypt the content inline */
+	if (!crypter->encrypt(crypter, ciphertext, iv, NULL))
+	{
+		DBG1(DBG_ESP, "ESP encryption failed");
+		writer->destroy(writer);
+		return FAILED;
+	}
+
+	/* calculate signature */
+	auth_data = writer->get_buf(writer);
+	icv = writer->skip(writer, icv.len);
+	if (!signer->get_signature(signer, auth_data, icv.ptr))
+	{
+		DBG1(DBG_ESP, "ESP encryption failed: signature generation failed");
+		writer->destroy(writer);
+		return FAILED;
+	}
+
+	DBG3(DBG_ESP, "ESP packet:\n  SPI %.8x [seq %u]\n  IV %B\n  "
+		 "encrypted %B\n  ICV %B", ntohl(spi), next_seqno, &iv,
+		 &ciphertext, &icv);
+
+	this->packet->set_data(this->packet, writer->extract_buf(writer));
+	writer->destroy(writer);
+	return SUCCESS;
+}
+
+METHOD(esp_packet_t, get_next_header, u_int8_t,
+	private_esp_packet_t *this)
+{
+	return this->next_header;
+}
+
+METHOD(esp_packet_t, get_payload, ip_packet_t*,
+	private_esp_packet_t *this)
+{
+	return this->payload;
+}
+
+METHOD(esp_packet_t, extract_payload, ip_packet_t*,
+	private_esp_packet_t *this)
+{
+	ip_packet_t *payload;
+
+	payload = this->payload;
+	this->payload = NULL;
+	return payload;
+}
+
+METHOD2(esp_packet_t, packet_t, destroy, void,
+	private_esp_packet_t *this)
+{
+	DESTROY_IF(this->payload);
+	this->packet->destroy(this->packet);
+	free(this);
+}
+
+static private_esp_packet_t *esp_packet_create_internal(packet_t *packet)
+{
+	private_esp_packet_t *this;
+
+	INIT(this,
+		.public = {
+			.packet = {
+				.set_source = _set_source,
+				.get_source = _get_source,
+				.set_destination = _set_destination,
+				.get_destination = _get_destination,
+				.get_data = _get_data,
+				.set_data = _set_data,
+				.skip_bytes = _skip_bytes,
+				.clone = _clone,
+				.destroy = _destroy,
+			},
+			.get_source = _get_source,
+			.get_destination = _get_destination,
+			.get_next_header = _get_next_header,
+			.parse_header = _parse_header,
+			.decrypt = _decrypt,
+			.encrypt = _encrypt,
+			.get_payload = _get_payload,
+			.extract_payload = _extract_payload,
+			.destroy = _destroy,
+		},
+		.packet = packet,
+		.next_header = IPPROTO_NONE,
+	);
+	return this;
+}
+
+/**
+ * Described in header.
+ */
+esp_packet_t *esp_packet_create_from_packet(packet_t *packet)
+{
+	private_esp_packet_t *this;
+
+	this = esp_packet_create_internal(packet);
+
+	return &this->public;
+}
+
+/**
+ * Described in header.
+ */
+esp_packet_t *esp_packet_create_from_payload(host_t *src, host_t *dst,
+											 ip_packet_t *payload)
+{
+	private_esp_packet_t *this;
+	packet_t *packet;
+
+	packet = packet_create_from_data(src, dst, chunk_empty);
+	this = esp_packet_create_internal(packet);
+	this->payload = payload;
+	if (payload)
+	{
+		this->next_header = payload->get_version(payload) == 4 ? IPPROTO_IPIP
+															   : IPPROTO_IPV6;
+	}
+	else
+	{
+		this->next_header = IPPROTO_NONE;
+	}
+	return &this->public;
+}