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>

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);
+
+	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[0] = version == TLS_1_3_VERSION ?
-	buf[1] = TLS_VERSION_MINOR(ctx->crypto_send.info.version);
+		   TLS_RECORD_TYPE_DATA : record_type;
-	buf[2] = TLS_VERSION_MAJOR(ctx->crypto_send.info.version);
+	/* 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[8] = record_type;
+	buf[0] = version == TLS_1_3_VERSION ?
-	buf[9] = TLS_1_2_VERSION_MAJOR;
+		  TLS_RECORD_TYPE_DATA : record_type;
-	buf[10] = TLS_1_2_VERSION_MINOR;
+	buf[1] = TLS_1_2_VERSION_MAJOR;
-	buf[11] = size >> 8;
+	buf[2] = TLS_1_2_VERSION_MINOR;
-	buf[12] = size & 0xFF;
+	buf[3] = size >> 8;
+	buf[4] = size & 0xFF;
+}
+
+static inline void xor_iv_with_seq(int version, char *iv, char *seq)
+{
+	int i;
+
+	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)

include/uapi/linux/tls.h

@@ -51,6 +51,10 @@
 #define TLS_1_2_VERSION_MINOR	0x3
 #define TLS_1_2_VERSION		TLS_VERSION_NUMBER(TLS_1_2)
 
+#define TLS_1_3_VERSION_MAJOR	0x3
+#define TLS_1_3_VERSION_MINOR	0x4
+#define TLS_1_3_VERSION		TLS_VERSION_NUMBER(TLS_1_3)
+
 /* Supported ciphers */
 #define TLS_CIPHER_AES_GCM_128				51
 #define TLS_CIPHER_AES_GCM_128_IV_SIZE			8

net/tls/tls_device.c

@@ -257,7 +257,8 @@ static int tls_push_record(struct sock *sk,
 	tls_fill_prepend(ctx,
 			 skb_frag_address(frag),
 			 record->len - ctx->tx.prepend_size,
-			 record_type);
+			 record_type,
+			 ctx->crypto_send.info.version);
 
 	/* HW doesn't care about the data in the tag, because it fills it. */
 	dummy_tag_frag.page = skb_frag_page(frag);
@@ -270,7 +271,7 @@ static int tls_push_record(struct sock *sk,
 	spin_unlock_irq(&offload_ctx->lock);
 	offload_ctx->open_record = NULL;
 	set_bit(TLS_PENDING_CLOSED_RECORD, &ctx->flags);
-	tls_advance_record_sn(sk, &ctx->tx);
+	tls_advance_record_sn(sk, &ctx->tx, ctx->crypto_send.info.version);
 
 	for (i = 0; i < record->num_frags; i++) {
 		frag = &record->frags[i];

net/tls/tls_device_fallback.c

@@ -73,7 +73,8 @@ static int tls_enc_record(struct aead_request *aead_req,
 	len -= TLS_CIPHER_AES_GCM_128_IV_SIZE;
 
 	tls_make_aad(aad, len - TLS_CIPHER_AES_GCM_128_TAG_SIZE,
-		     (char *)&rcd_sn, sizeof(rcd_sn), buf[0]);
+		(char *)&rcd_sn, sizeof(rcd_sn), buf[0],
+		TLS_1_2_VERSION);
 
 	memcpy(iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE, buf + TLS_HEADER_SIZE,
 	       TLS_CIPHER_AES_GCM_128_IV_SIZE);

net/tls/tls_main.c

@@ -463,7 +463,8 @@ static int do_tls_setsockopt_conf(struct sock *sk, char __user *optval,
 	}
 
 	/* check version */
-	if (crypto_info->version != TLS_1_2_VERSION) {
+	if (crypto_info->version != TLS_1_2_VERSION &&
+	    crypto_info->version != TLS_1_3_VERSION) {
 		rc = -ENOTSUPP;
 		goto err_crypto_info;
 	}

net/tls/tls_sw.c

@@ -120,6 +120,34 @@ static int skb_nsg(struct sk_buff *skb, int offset, int len)
         return __skb_nsg(skb, offset, len, 0);
 }
 
+static int padding_length(struct tls_sw_context_rx *ctx,
+			  struct tls_context *tls_ctx, struct sk_buff *skb)
+{
+	struct strp_msg *rxm = strp_msg(skb);
+	int sub = 0;
+
+	/* Determine zero-padding length */
+	if (tls_ctx->crypto_recv.info.version == TLS_1_3_VERSION) {
+		char content_type = 0;
+		int err;
+		int back = 17;
+
+		while (content_type == 0) {
+			if (back > rxm->full_len)
+				return -EBADMSG;
+			err = skb_copy_bits(skb,
+					    rxm->offset + rxm->full_len - back,
+					    &content_type, 1);
+			if (content_type)
+				break;
+			sub++;
+			back++;
+		}
+		ctx->control = content_type;
+	}
+	return sub;
+}
+
 static void tls_decrypt_done(struct crypto_async_request *req, int err)
 {
 	struct aead_request *aead_req = (struct aead_request *)req;
@@ -142,7 +170,7 @@ static void tls_decrypt_done(struct crypto_async_request *req, int err)
 		tls_err_abort(skb->sk, err);
 	} else {
 		struct strp_msg *rxm = strp_msg(skb);
-
+		rxm->full_len -= padding_length(ctx, tls_ctx, skb);
 		rxm->offset += tls_ctx->rx.prepend_size;
 		rxm->full_len -= tls_ctx->rx.overhead_size;
 	}
@@ -448,6 +476,8 @@ static int tls_do_encryption(struct sock *sk,
 	int rc;
 
 	memcpy(rec->iv_data, tls_ctx->tx.iv, sizeof(rec->iv_data));
+	xor_iv_with_seq(tls_ctx->crypto_send.info.version, rec->iv_data,
+			tls_ctx->tx.rec_seq);
 
 	sge->offset += tls_ctx->tx.prepend_size;
 	sge->length -= tls_ctx->tx.prepend_size;
@@ -483,7 +513,8 @@ static int tls_do_encryption(struct sock *sk,
 
 	/* Unhook the record from context if encryption is not failure */
 	ctx->open_rec = NULL;
-	tls_advance_record_sn(sk, &tls_ctx->tx);
+	tls_advance_record_sn(sk, &tls_ctx->tx,
+			      tls_ctx->crypto_send.info.version);
 	return rc;
 }
 
@@ -640,7 +671,17 @@ static int tls_push_record(struct sock *sk, int flags,
 
 	i = msg_pl->sg.end;
 	sk_msg_iter_var_prev(i);
+
+	rec->content_type = record_type;
+	if (tls_ctx->crypto_send.info.version == TLS_1_3_VERSION) {
+		/* Add content type to end of message.  No padding added */
+		sg_set_buf(&rec->sg_content_type, &rec->content_type, 1);
+		sg_mark_end(&rec->sg_content_type);
+		sg_chain(msg_pl->sg.data, msg_pl->sg.end + 1,
+			 &rec->sg_content_type);
+	} else {
 		sg_mark_end(sk_msg_elem(msg_pl, i));
+	}
 
 	i = msg_pl->sg.start;
 	sg_chain(rec->sg_aead_in, 2, rec->inplace_crypto ?
@@ -653,18 +694,22 @@ static int tls_push_record(struct sock *sk, int flags,
 	i = msg_en->sg.start;
 	sg_chain(rec->sg_aead_out, 2, &msg_en->sg.data[i]);
 
-	tls_make_aad(rec->aad_space, msg_pl->sg.size,
+	tls_make_aad(rec->aad_space, msg_pl->sg.size + tls_ctx->tx.tail_size,
 		     tls_ctx->tx.rec_seq, tls_ctx->tx.rec_seq_size,
-		     record_type);
+		     record_type,
+		     tls_ctx->crypto_send.info.version);
 
 	tls_fill_prepend(tls_ctx,
 			 page_address(sg_page(&msg_en->sg.data[i])) +
-			 msg_en->sg.data[i].offset, msg_pl->sg.size,
+			 msg_en->sg.data[i].offset,
-			 record_type);
+			 msg_pl->sg.size + tls_ctx->tx.tail_size,
+			 record_type,
+			 tls_ctx->crypto_send.info.version);
 
 	tls_ctx->pending_open_record_frags = false;
 
-	rc = tls_do_encryption(sk, tls_ctx, ctx, req, msg_pl->sg.size, i);
+	rc = tls_do_encryption(sk, tls_ctx, ctx, req,
+			       msg_pl->sg.size + tls_ctx->tx.tail_size, i);
 	if (rc < 0) {
 		if (rc != -EINPROGRESS) {
 			tls_err_abort(sk, EBADMSG);
@@ -1292,7 +1337,8 @@ static int decrypt_internal(struct sock *sk, struct sk_buff *skb,
 	u8 *aad, *iv, *mem = NULL;
 	struct scatterlist *sgin = NULL;
 	struct scatterlist *sgout = NULL;
-	const int data_len = rxm->full_len - tls_ctx->rx.overhead_size;
+	const int data_len = rxm->full_len - tls_ctx->rx.overhead_size +
+		tls_ctx->rx.tail_size;
 
 	if (*zc && (out_iov || out_sg)) {
 		if (out_iov)
@@ -1343,12 +1389,20 @@ static int decrypt_internal(struct sock *sk, struct sk_buff *skb,
 		kfree(mem);
 		return err;
 	}
+	if (tls_ctx->crypto_recv.info.version == TLS_1_3_VERSION)
+		memcpy(iv, tls_ctx->rx.iv, crypto_aead_ivsize(ctx->aead_recv));
+	else
 		memcpy(iv, tls_ctx->rx.iv, TLS_CIPHER_AES_GCM_128_SALT_SIZE);
 
+	xor_iv_with_seq(tls_ctx->crypto_recv.info.version, iv,
+			tls_ctx->rx.rec_seq);
+
 	/* Prepare AAD */
-	tls_make_aad(aad, rxm->full_len - tls_ctx->rx.overhead_size,
+	tls_make_aad(aad, rxm->full_len - tls_ctx->rx.overhead_size +
+		     tls_ctx->rx.tail_size,
 		     tls_ctx->rx.rec_seq, tls_ctx->rx.rec_seq_size,
-		     ctx->control);
+		     ctx->control,
+		     tls_ctx->crypto_recv.info.version);
 
 	/* Prepare sgin */
 	sg_init_table(sgin, n_sgin);
@@ -1405,6 +1459,7 @@ static int decrypt_skb_update(struct sock *sk, struct sk_buff *skb,
 {
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	struct tls_sw_context_rx *ctx = tls_sw_ctx_rx(tls_ctx);
+	int version = tls_ctx->crypto_recv.info.version;
 	struct strp_msg *rxm = strp_msg(skb);
 	int err = 0;
 
@@ -1417,13 +1472,17 @@ static int decrypt_skb_update(struct sock *sk, struct sk_buff *skb,
 		err = decrypt_internal(sk, skb, dest, NULL, chunk, zc, async);
 		if (err < 0) {
 			if (err == -EINPROGRESS)
-				tls_advance_record_sn(sk, &tls_ctx->rx);
+				tls_advance_record_sn(sk, &tls_ctx->rx,
+						      version);
 
 			return err;
 		}
+
+		rxm->full_len -= padding_length(ctx, tls_ctx, skb);
+
 		rxm->offset += tls_ctx->rx.prepend_size;
 		rxm->full_len -= tls_ctx->rx.overhead_size;
-		tls_advance_record_sn(sk, &tls_ctx->rx);
+		tls_advance_record_sn(sk, &tls_ctx->rx, version);
 		ctx->decrypted = true;
 		ctx->saved_data_ready(sk);
 	} else {
@@ -1611,7 +1670,8 @@ int tls_sw_recvmsg(struct sock *sk,
 		to_decrypt = rxm->full_len - tls_ctx->rx.overhead_size;
 
 		if (to_decrypt <= len && !is_kvec && !is_peek &&
-		    ctx->control == TLS_RECORD_TYPE_DATA)
+		    ctx->control == TLS_RECORD_TYPE_DATA &&
+		    tls_ctx->crypto_recv.info.version != TLS_1_3_VERSION)
 			zc = true;
 
 		err = decrypt_skb_update(sk, skb, &msg->msg_iter,
@@ -1835,9 +1895,12 @@ static int tls_read_size(struct strparser *strp, struct sk_buff *skb)
 
 	data_len = ((header[4] & 0xFF) | (header[3] << 8));
 
-	cipher_overhead = tls_ctx->rx.tag_size + tls_ctx->rx.iv_size;
+	cipher_overhead = tls_ctx->rx.tag_size;
+	if (tls_ctx->crypto_recv.info.version != TLS_1_3_VERSION)
+		cipher_overhead += tls_ctx->rx.iv_size;
 
-	if (data_len > TLS_MAX_PAYLOAD_SIZE + cipher_overhead) {
+	if (data_len > TLS_MAX_PAYLOAD_SIZE + cipher_overhead +
+	    tls_ctx->rx.tail_size) {
 		ret = -EMSGSIZE;
 		goto read_failure;
 	}
@@ -1846,12 +1909,12 @@ static int tls_read_size(struct strparser *strp, struct sk_buff *skb)
 		goto read_failure;
 	}
 
-	if (header[1] != TLS_VERSION_MINOR(tls_ctx->crypto_recv.info.version) ||
+	/* Note that both TLS1.3 and TLS1.2 use TLS_1_2 version here */
-	    header[2] != TLS_VERSION_MAJOR(tls_ctx->crypto_recv.info.version)) {
+	if (header[1] != TLS_1_2_VERSION_MINOR ||
+	    header[2] != TLS_1_2_VERSION_MAJOR) {
 		ret = -EINVAL;
 		goto read_failure;
 	}
-
 #ifdef CONFIG_TLS_DEVICE
 	handle_device_resync(strp->sk, TCP_SKB_CB(skb)->seq + rxm->offset,
 			     *(u64*)tls_ctx->rx.rec_seq);
@@ -2100,10 +2163,19 @@ int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx)
 		goto free_priv;
 	}
 
+	if (crypto_info->version == TLS_1_3_VERSION) {
+		nonce_size = 0;
+		cctx->aad_size = TLS_HEADER_SIZE;
+		cctx->tail_size = 1;
+	} else {
 		cctx->aad_size = TLS_AAD_SPACE_SIZE;
+		cctx->tail_size = 0;
+	}
+
 	cctx->prepend_size = TLS_HEADER_SIZE + nonce_size;
 	cctx->tag_size = tag_size;
-	cctx->overhead_size = cctx->prepend_size + cctx->tag_size;
+	cctx->overhead_size = cctx->prepend_size + cctx->tag_size +
+		cctx->tail_size;
 	cctx->iv_size = iv_size;
 	cctx->iv = kmalloc(iv_size + TLS_CIPHER_AES_GCM_128_SALT_SIZE,
 			   GFP_KERNEL);