Start replacing the existing TLSv1.2 record layer.

This takes the same design/approach used in TLSv1.3 and provides an
opaque struct that is self contained and cannot reach back into other
layers. For now this just implements/replaces the writing of records
for DTLSv1/TLSv1.0/TLSv1.1/TLSv1.2. In doing so we stop copying the
plaintext into the same buffer that is used to transmit to the wire.

ok inoguchi@ tb@

1 files changed, 533 insertions, 0 deletions

diff --git a/lib/libssl/tls12_record_layer.c b/lib/libssl/tls12_record_layer.c
new file mode 100644
index 00000000000..5e7a3a610c6
--- /dev/null
+++ b/lib/libssl/tls12_record_layer.c
@@ -0,0 +1,533 @@
+/* $OpenBSD: tls12_record_layer.c,v 1.1 2020/08/30 15:40:20 jsing Exp $ */
+/*
+ * Copyright (c) 2020 Joel Sing <jsing@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <stdlib.h>
+
+#include <openssl/evp.h>
+
+#include "ssl_locl.h"
+
+struct tls12_record_layer {
+	uint16_t version;
+	int dtls;
+
+	uint16_t read_epoch;
+	uint16_t write_epoch;
+
+	int read_stream_mac;
+	int write_stream_mac;
+
+	/*
+	 * XXX - for now these are just pointers to externally managed
+	 * structs/memory. These should eventually be owned by the record layer.
+	 */
+	SSL_AEAD_CTX *read_aead_ctx;
+	SSL_AEAD_CTX *write_aead_ctx;
+
+	EVP_CIPHER_CTX *read_cipher_ctx;
+	EVP_MD_CTX *read_hash_ctx;
+	EVP_CIPHER_CTX *write_cipher_ctx;
+	EVP_MD_CTX *write_hash_ctx;
+
+	uint8_t *read_seq_num;
+	uint8_t *write_seq_num;
+};
+
+struct tls12_record_layer *
+tls12_record_layer_new(void)
+{
+	struct tls12_record_layer *rl;
+
+	if ((rl = calloc(1, sizeof(struct tls12_record_layer))) == NULL)
+		return NULL;
+
+	return rl;
+}
+
+void
+tls12_record_layer_free(struct tls12_record_layer *rl)
+{
+	freezero(rl, sizeof(struct tls12_record_layer));
+}
+
+void
+tls12_record_layer_set_version(struct tls12_record_layer *rl, uint16_t version)
+{
+	rl->version = version;
+	rl->dtls = (version == DTLS1_VERSION);
+}
+
+void
+tls12_record_layer_set_read_epoch(struct tls12_record_layer *rl, uint16_t epoch)
+{
+	rl->read_epoch = epoch;
+}
+
+void
+tls12_record_layer_set_write_epoch(struct tls12_record_layer *rl, uint16_t epoch)
+{
+	rl->write_epoch = epoch;
+}
+
+static void
+tls12_record_layer_set_read_state(struct tls12_record_layer *rl,
+    SSL_AEAD_CTX *aead_ctx, EVP_CIPHER_CTX *cipher_ctx, EVP_MD_CTX *hash_ctx,
+    int stream_mac)
+{
+	rl->read_aead_ctx = aead_ctx;
+
+	rl->read_cipher_ctx = cipher_ctx;
+	rl->read_hash_ctx = hash_ctx;
+	rl->read_stream_mac = stream_mac;
+}
+
+static void
+tls12_record_layer_set_write_state(struct tls12_record_layer *rl,
+    SSL_AEAD_CTX *aead_ctx, EVP_CIPHER_CTX *cipher_ctx, EVP_MD_CTX *hash_ctx,
+    int stream_mac)
+{
+	rl->write_aead_ctx = aead_ctx;
+
+	rl->write_cipher_ctx = cipher_ctx;
+	rl->write_hash_ctx = hash_ctx;
+	rl->write_stream_mac = stream_mac;
+}
+
+void
+tls12_record_layer_clear_read_state(struct tls12_record_layer *rl)
+{
+	tls12_record_layer_set_read_state(rl, NULL, NULL, NULL, 0);
+	rl->read_seq_num = NULL;
+}
+
+void
+tls12_record_layer_clear_write_state(struct tls12_record_layer *rl)
+{
+	tls12_record_layer_set_write_state(rl, NULL, NULL, NULL, 0);
+	rl->write_seq_num = NULL;
+}
+
+void
+tls12_record_layer_set_read_seq_num(struct tls12_record_layer *rl,
+    uint8_t *seq_num)
+{
+	rl->read_seq_num = seq_num;
+}
+
+void
+tls12_record_layer_set_write_seq_num(struct tls12_record_layer *rl,
+    uint8_t *seq_num)
+{
+	rl->write_seq_num = seq_num;
+}
+
+int
+tls12_record_layer_set_read_aead(struct tls12_record_layer *rl,
+    SSL_AEAD_CTX *aead_ctx)
+{
+	tls12_record_layer_set_read_state(rl, aead_ctx, NULL, NULL, 0);
+
+	return 1;
+}
+
+int
+tls12_record_layer_set_write_aead(struct tls12_record_layer *rl,
+    SSL_AEAD_CTX *aead_ctx)
+{
+	tls12_record_layer_set_write_state(rl, aead_ctx, NULL, NULL, 0);
+
+	return 1;
+}
+
+int
+tls12_record_layer_set_read_cipher_hash(struct tls12_record_layer *rl,
+    EVP_CIPHER_CTX *cipher_ctx, EVP_MD_CTX *hash_ctx, int stream_mac)
+{
+	tls12_record_layer_set_read_state(rl, NULL, cipher_ctx, hash_ctx,
+	    stream_mac);
+
+	return 1;
+}
+
+int
+tls12_record_layer_set_write_cipher_hash(struct tls12_record_layer *rl,
+    EVP_CIPHER_CTX *cipher_ctx, EVP_MD_CTX *hash_ctx, int stream_mac)
+{
+	tls12_record_layer_set_write_state(rl, NULL, cipher_ctx, hash_ctx,
+	    stream_mac);
+
+	return 1;
+}
+
+static int
+tls12_record_layer_build_seq_num(struct tls12_record_layer *rl, CBB *cbb,
+    uint16_t epoch, uint8_t *seq_num, size_t seq_num_len)
+{
+	CBS seq;
+
+	CBS_init(&seq, seq_num, seq_num_len);
+
+	if (rl->dtls) {
+		if (!CBB_add_u16(cbb, epoch))
+			return 0;
+		if (!CBS_skip(&seq, 2))
+			return 0;
+	}
+
+	return CBB_add_bytes(cbb, CBS_data(&seq), CBS_len(&seq));
+}
+
+static int
+tls12_record_layer_pseudo_header(struct tls12_record_layer *rl,
+    uint8_t content_type, uint16_t record_len, uint16_t epoch, uint8_t *seq_num,
+    size_t seq_num_len, uint8_t **out, size_t *out_len)
+{
+	CBB cbb;
+
+	*out = NULL;
+	*out_len = 0;
+
+	/* Build the pseudo-header used for MAC/AEAD. */
+	if (!CBB_init(&cbb, 13))
+		goto err;
+
+	if (!tls12_record_layer_build_seq_num(rl, &cbb, epoch,
+	    seq_num, seq_num_len))
+		goto err;
+	if (!CBB_add_u8(&cbb, content_type))
+		goto err;
+	if (!CBB_add_u16(&cbb, rl->version))
+		goto err;
+	if (!CBB_add_u16(&cbb, record_len))
+		goto err;
+
+	if (!CBB_finish(&cbb, out, out_len))
+		goto err;
+
+	return 1;
+
+ err:
+	CBB_cleanup(&cbb);
+
+	return 0;
+}
+
+static int
+tls12_record_layer_write_mac(struct tls12_record_layer *rl, CBB *cbb,
+    uint8_t content_type, const uint8_t *content, size_t content_len,
+    size_t *out_len)
+{
+	EVP_MD_CTX *mac_ctx = NULL;
+	uint8_t *header = NULL;
+	size_t header_len;
+	size_t mac_len;
+	uint8_t *mac;
+	int ret = 0;
+
+	if ((mac_ctx = EVP_MD_CTX_new()) == NULL)
+		goto err;
+	if (!EVP_MD_CTX_copy(mac_ctx, rl->write_hash_ctx))
+		goto err;
+
+	if (!tls12_record_layer_pseudo_header(rl, content_type, content_len,
+	    rl->write_epoch, rl->write_seq_num, SSL3_SEQUENCE_SIZE,
+	    &header, &header_len))
+		goto err;
+
+	if (EVP_DigestSignUpdate(mac_ctx, header, header_len) <= 0)
+		goto err;
+	if (EVP_DigestSignUpdate(mac_ctx, content, content_len) <= 0)
+		goto err;
+	if (EVP_DigestSignFinal(mac_ctx, NULL, &mac_len) <= 0)
+		goto err;
+	if (!CBB_add_space(cbb, &mac, mac_len))
+		goto err;
+	if (EVP_DigestSignFinal(mac_ctx, mac, &mac_len) <= 0)
+		goto err;
+
+	if (rl->write_stream_mac) {
+		if (!EVP_MD_CTX_copy(rl->write_hash_ctx, mac_ctx))
+			goto err;
+	}
+
+	*out_len = mac_len;
+
+	ret = 1;
+
+ err:
+	EVP_MD_CTX_free(mac_ctx);
+	free(header);
+
+	return ret;
+}
+
+static int
+tls12_record_layer_seal_record_plaintext(struct tls12_record_layer *rl,
+    uint8_t content_type, const uint8_t *content, size_t content_len, CBB *out)
+{
+	if (rl->write_aead_ctx != NULL || rl->write_cipher_ctx != NULL)
+		return 0;
+
+	return CBB_add_bytes(out, content, content_len);
+}
+
+static int
+tls12_record_layer_aead_concat_nonce(struct tls12_record_layer *rl,
+    const SSL_AEAD_CTX *aead, uint8_t *seq_num, uint8_t **out, size_t *out_len)
+{
+	CBB cbb;
+
+	if (aead->variable_nonce_len > SSL3_SEQUENCE_SIZE)
+		return 0;
+
+	/* Fixed nonce and variable nonce (sequence number) are concatenated. */
+	if (!CBB_init(&cbb, 16))
+		goto err;
+	if (!CBB_add_bytes(&cbb, aead->fixed_nonce,
+	    aead->fixed_nonce_len))
+		goto err;
+	if (!CBB_add_bytes(&cbb, seq_num, aead->variable_nonce_len))
+		goto err;
+	if (!CBB_finish(&cbb, out, out_len))
+		goto err;
+
+	return 1;
+
+ err:
+	CBB_cleanup(&cbb);
+
+	return 0;
+}
+
+static int
+tls12_record_layer_aead_xored_nonce(struct tls12_record_layer *rl,
+    const SSL_AEAD_CTX *aead, uint8_t *seq_num, uint8_t **out, size_t *out_len)
+{
+	uint8_t *nonce = NULL;
+	size_t nonce_len = 0;
+	uint8_t *pad;
+	CBB cbb;
+	int i;
+
+	if (aead->variable_nonce_len > SSL3_SEQUENCE_SIZE)
+		return 0;
+	if (aead->fixed_nonce_len < aead->variable_nonce_len)
+		return 0;
+
+	/*
+	 * Variable nonce (sequence number) is right padded, before the fixed
+	 * nonce is XOR'd in.
+	 */
+	if (!CBB_init(&cbb, 16))
+		goto err;
+	if (!CBB_add_space(&cbb, &pad,
+	    aead->fixed_nonce_len - aead->variable_nonce_len))
+		goto err;
+	if (!CBB_add_bytes(&cbb, seq_num, aead->variable_nonce_len))
+		goto err;
+	if (!CBB_finish(&cbb, &nonce, &nonce_len))
+		goto err;
+
+	for (i = 0; i < aead->fixed_nonce_len; i++)
+		nonce[i] ^= aead->fixed_nonce[i];
+
+	*out = nonce;
+	*out_len = nonce_len;
+
+	return 1;
+
+ err:
+	CBB_cleanup(&cbb);
+	freezero(nonce, nonce_len);
+
+	return 0;
+}
+
+static int
+tls12_record_layer_seal_record_protected_aead(struct tls12_record_layer *rl,
+    uint8_t content_type, const uint8_t *content, size_t content_len, CBB *out)
+{
+	const SSL_AEAD_CTX *aead = rl->write_aead_ctx;
+	uint8_t *header = NULL, *nonce = NULL;
+	size_t header_len = 0, nonce_len = 0;
+	size_t enc_record_len, out_len;
+	uint16_t epoch = 0;
+	uint8_t *enc_data;
+	int ret = 0;
+
+	/* XXX - move to nonce allocated in record layer, matching TLSv1.3 */
+	if (aead->xor_fixed_nonce) {
+		if (!tls12_record_layer_aead_xored_nonce(rl, aead,
+		    rl->write_seq_num, &nonce, &nonce_len))
+			goto err;
+	} else {
+		if (!tls12_record_layer_aead_concat_nonce(rl, aead,
+		    rl->write_seq_num, &nonce, &nonce_len))
+			goto err;
+	}
+
+	if (aead->variable_nonce_in_record) {
+		/* XXX - length check? */
+		if (!CBB_add_bytes(out, rl->write_seq_num, aead->variable_nonce_len))
+			goto err;
+	}
+
+	if (!tls12_record_layer_pseudo_header(rl, content_type, content_len,
+	    epoch, rl->write_seq_num, SSL3_SEQUENCE_SIZE, &header, &header_len))
+		goto err;
+
+	/* XXX EVP_AEAD_max_tag_len vs EVP_AEAD_CTX_tag_len. */
+	enc_record_len = content_len + aead->tag_len;
+	if (enc_record_len > SSL3_RT_MAX_ENCRYPTED_LENGTH)
+		goto err;
+	if (!CBB_add_space(out, &enc_data, enc_record_len))
+		goto err;
+
+	if (!EVP_AEAD_CTX_seal(&aead->ctx, enc_data, &out_len, enc_record_len,
+	    nonce, nonce_len, content, content_len, header, header_len))
+		goto err;
+
+	if (out_len != enc_record_len)
+		goto err;
+
+	ret = 1;
+
+ err:
+	freezero(header, header_len);
+	freezero(nonce, nonce_len);
+
+	return ret;
+}
+
+static int
+tls12_record_layer_seal_record_protected_cipher(struct tls12_record_layer *rl,
+    uint8_t content_type, const uint8_t *content, size_t content_len, CBB *out)
+{
+	EVP_CIPHER_CTX *enc = rl->write_cipher_ctx;
+	size_t mac_len, pad_len;
+	int block_size, eiv_len;
+	uint8_t *enc_data, *eiv, *pad, pad_val;
+	uint8_t *plain = NULL;
+	size_t plain_len = 0;
+	int ret = 0;
+	CBB cbb;
+
+	if (!CBB_init(&cbb, SSL3_RT_MAX_PLAIN_LENGTH))
+		goto err;
+
+	/* Add explicit IV if necessary. */
+	eiv_len = 0;
+	if (rl->version != TLS1_VERSION &&
+	    EVP_CIPHER_CTX_mode(enc) == EVP_CIPH_CBC_MODE)
+		eiv_len = EVP_CIPHER_CTX_iv_length(enc);
+	if (eiv_len < 0 || eiv_len > EVP_MAX_IV_LENGTH)
+		goto err;
+	if (eiv_len > 0) {
+		if (!CBB_add_space(&cbb, &eiv, eiv_len))
+			goto err;
+		arc4random_buf(eiv, eiv_len);
+	}
+
+	if (!CBB_add_bytes(&cbb, content, content_len))
+		goto err;
+
+	mac_len = 0;
+	if (rl->write_hash_ctx != NULL) {
+		if (!tls12_record_layer_write_mac(rl, &cbb, content_type,
+		    content, content_len, &mac_len))
+			goto err;
+	}
+
+	plain_len = (size_t)eiv_len + content_len + mac_len;
+
+	/* Add padding to block size, if necessary. */
+	block_size = EVP_CIPHER_CTX_block_size(enc);
+	if (block_size < 0 || block_size > EVP_MAX_BLOCK_LENGTH)
+		return 0;
+	if (block_size > 1) {
+		pad_len = block_size - (plain_len % block_size);
+		pad_val = pad_len - 1;
+
+		if (pad_len > 255)
+			goto err;
+		if (!CBB_add_space(&cbb, &pad, pad_len))
+			goto err;
+		memset(pad, pad_val, pad_len);
+	}
+
+	if (!CBB_finish(&cbb, &plain, &plain_len))
+		goto err;
+
+	if (plain_len % block_size != 0)
+		goto err;
+	if (plain_len > SSL3_RT_MAX_ENCRYPTED_LENGTH)
+		goto err;
+
+	if (!CBB_add_space(out, &enc_data, plain_len))
+		goto err;
+	if (!EVP_Cipher(enc, enc_data, plain, plain_len))
+		goto err;
+
+	ret = 1;
+
+ err:
+	CBB_cleanup(&cbb);
+	freezero(plain, plain_len);
+
+	return ret;
+}
+
+int
+tls12_record_layer_seal_record(struct tls12_record_layer *rl,
+    uint8_t content_type, const uint8_t *content, size_t content_len, CBB *cbb)
+{
+	CBB fragment;
+
+	if (!CBB_add_u8(cbb, content_type))
+		return 0;
+	if (!CBB_add_u16(cbb, rl->version))
+		return 0;
+	if (rl->dtls) {
+		if (!tls12_record_layer_build_seq_num(rl, cbb,
+		    rl->write_epoch, rl->write_seq_num,
+		    SSL3_SEQUENCE_SIZE))
+			return 0;
+	}
+	if (!CBB_add_u16_length_prefixed(cbb, &fragment))
+		return 0;
+
+	if (rl->write_aead_ctx != NULL) {
+		if (!tls12_record_layer_seal_record_protected_aead(rl,
+		    content_type, content, content_len, &fragment))
+			return 0;
+	} else if (rl->write_cipher_ctx != NULL) {
+		if (!tls12_record_layer_seal_record_protected_cipher(rl,
+		    content_type, content, content_len, &fragment))
+			return 0;
+	} else {
+		if (!tls12_record_layer_seal_record_plaintext(rl,
+		    content_type, content, content_len, &fragment))
+			return 0;
+	}
+
+	if (!CBB_flush(cbb))
+		return 0;
+
+	tls1_record_sequence_increment(rl->write_seq_num);
+
+	return 1;
+}