net: tls: Add tls 1.3 support

TLS 1.3 has minor changes from TLS 1.2 at the record layer.

* Header now hardcodes the same version and application content type in
  the header.
* The real content type is appended after the data, before encryption (or
  after decryption).
* The IV is xored with the sequence number, instead of concatinating four
  bytes of IV with the explicit IV.
* Zero-padding:  No exlicit length is given, we search backwards from the
  end of the decrypted data for the first non-zero byte, which is the
  content type.  Currently recv supports reading zero-padding, but there
  is no way for send to add zero padding.

Signed-off-by: Dave Watson <davejwatson@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 49 insertions, 17 deletions

diff --git a/include/net/tls.h b/include/net/tls.h
index 754b130672f0..004bf01ce868 100644
--- a/include/net/tls.h
+++ b/include/net/tls.h
@@ -119,6 +119,9 @@ struct tls_rec {
 	/* AAD | msg_encrypted.sg.data (data contains overhead for hdr & iv & tag) */
 	struct scatterlist sg_aead_out[2];
 
+	char content_type;
+	struct scatterlist sg_content_type;
+
 	char aad_space[TLS_AAD_SPACE_SIZE];
 	u8 iv_data[TLS_CIPHER_AES_GCM_128_IV_SIZE +
 		   TLS_CIPHER_AES_GCM_128_SALT_SIZE];
@@ -203,6 +206,7 @@ struct cipher_context {
 	u16 rec_seq_size;
 	char *rec_seq;
 	u16 aad_size;
+	u16 tail_size;
 };
 
 union tls_crypto_context {
@@ -397,49 +401,77 @@ static inline bool tls_bigint_increment(unsigned char *seq, int len)
 }
 
 static inline void tls_advance_record_sn(struct sock *sk,
-					 struct cipher_context *ctx)
+					 struct cipher_context *ctx,
+					 int version)
 {
 	if (tls_bigint_increment(ctx->rec_seq, ctx->rec_seq_size))
 		tls_err_abort(sk, EBADMSG);
-	tls_bigint_increment(ctx->iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE,
-			     ctx->iv_size);
+
+	if (version != TLS_1_3_VERSION) {
+		tls_bigint_increment(ctx->iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE,
+				     ctx->iv_size);
+	}
 }
 
 static inline void tls_fill_prepend(struct tls_context *ctx,
 			     char *buf,
 			     size_t plaintext_len,
-			     unsigned char record_type)
+			     unsigned char record_type,
+			     int version)
 {
 	size_t pkt_len, iv_size = ctx->tx.iv_size;
 
-	pkt_len = plaintext_len + iv_size + ctx->tx.tag_size;
+	pkt_len = plaintext_len + ctx->tx.tag_size;
+	if (version != TLS_1_3_VERSION) {
+		pkt_len += iv_size;
+
+		memcpy(buf + TLS_NONCE_OFFSET,
+		       ctx->tx.iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE, iv_size);
+	}
 
 	/* we cover nonce explicit here as well, so buf should be of
 	 * size KTLS_DTLS_HEADER_SIZE + KTLS_DTLS_NONCE_EXPLICIT_SIZE
 	 */
-	buf[0] = record_type;
-	buf[1] = TLS_VERSION_MINOR(ctx->crypto_send.info.version);
-	buf[2] = TLS_VERSION_MAJOR(ctx->crypto_send.info.version);
+	buf[0] = version == TLS_1_3_VERSION ?
+		   TLS_RECORD_TYPE_DATA : record_type;
+	/* Note that VERSION must be TLS_1_2 for both TLS1.2 and TLS1.3 */
+	buf[1] = TLS_1_2_VERSION_MINOR;
+	buf[2] = TLS_1_2_VERSION_MAJOR;
 	/* we can use IV for nonce explicit according to spec */
 	buf[3] = pkt_len >> 8;
 	buf[4] = pkt_len & 0xFF;
-	memcpy(buf + TLS_NONCE_OFFSET,
-	       ctx->tx.iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE, iv_size);
 }
 
 static inline void tls_make_aad(char *buf,
 				size_t size,
 				char *record_sequence,
 				int record_sequence_size,
-				unsigned char record_type)
+				unsigned char record_type,
+				int version)
+{
+	if (version != TLS_1_3_VERSION) {
+		memcpy(buf, record_sequence, record_sequence_size);
+		buf += 8;
+	} else {
+		size += TLS_CIPHER_AES_GCM_128_TAG_SIZE;
+	}
+
+	buf[0] = version == TLS_1_3_VERSION ?
+		  TLS_RECORD_TYPE_DATA : record_type;
+	buf[1] = TLS_1_2_VERSION_MAJOR;
+	buf[2] = TLS_1_2_VERSION_MINOR;
+	buf[3] = size >> 8;
+	buf[4] = size & 0xFF;
+}
+
+static inline void xor_iv_with_seq(int version, char *iv, char *seq)
 {
-	memcpy(buf, record_sequence, record_sequence_size);
+	int i;
 
-	buf[8] = record_type;
-	buf[9] = TLS_1_2_VERSION_MAJOR;
-	buf[10] = TLS_1_2_VERSION_MINOR;
-	buf[11] = size >> 8;
-	buf[12] = size & 0xFF;
+	if (version == TLS_1_3_VERSION) {
+		for (i = 0; i < 8; i++)
+			iv[i + 4] ^= seq[i];
+	}
 }
 
 static inline struct tls_context *tls_get_ctx(const struct sock *sk)