net: tls: Refactor tls aad space size calculation

TLS 1.3 has a different AAD size, use a variable in the code to
make TLS 1.3 support easy.

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

Author: Dave Watson

include/net/tls.h

@@ -202,6 +202,7 @@ struct cipher_context {
 	char *iv;
 	u16 rec_seq_size;
 	char *rec_seq;
+	u16 aad_size;
 };
 
 union tls_crypto_context {

net/tls/tls_sw.c

@@ -185,7 +185,7 @@ static int tls_do_decryption(struct sock *sk,
 	int ret;
 
 	aead_request_set_tfm(aead_req, ctx->aead_recv);
-	aead_request_set_ad(aead_req, TLS_AAD_SPACE_SIZE);
+	aead_request_set_ad(aead_req, tls_ctx->rx.aad_size);
 	aead_request_set_crypt(aead_req, sgin, sgout,
 			       data_len + tls_ctx->rx.tag_size,
 			       (u8 *)iv_recv);
@@ -289,12 +289,12 @@ static struct tls_rec *tls_get_rec(struct sock *sk)
 
 	sg_init_table(rec->sg_aead_in, 2);
 	sg_set_buf(&rec->sg_aead_in[0], rec->aad_space,
-		   sizeof(rec->aad_space));
+		   tls_ctx->tx.aad_size);
 	sg_unmark_end(&rec->sg_aead_in[1]);
 
 	sg_init_table(rec->sg_aead_out, 2);
 	sg_set_buf(&rec->sg_aead_out[0], rec->aad_space,
-		   sizeof(rec->aad_space));
+		   tls_ctx->tx.aad_size);
 	sg_unmark_end(&rec->sg_aead_out[1]);
 
 	return rec;
@@ -455,7 +455,7 @@ static int tls_do_encryption(struct sock *sk,
 	msg_en->sg.curr = start;
 
 	aead_request_set_tfm(aead_req, ctx->aead_send);
-	aead_request_set_ad(aead_req, TLS_AAD_SPACE_SIZE);
+	aead_request_set_ad(aead_req, tls_ctx->tx.aad_size);
 	aead_request_set_crypt(aead_req, rec->sg_aead_in,
 			       rec->sg_aead_out,
 			       data_len, rec->iv_data);
@@ -1317,7 +1317,7 @@ static int decrypt_internal(struct sock *sk, struct sk_buff *skb,
 
 	aead_size = sizeof(*aead_req) + crypto_aead_reqsize(ctx->aead_recv);
 	mem_size = aead_size + (nsg * sizeof(struct scatterlist));
-	mem_size = mem_size + TLS_AAD_SPACE_SIZE;
+	mem_size = mem_size + tls_ctx->rx.aad_size;
 	mem_size = mem_size + crypto_aead_ivsize(ctx->aead_recv);
 
 	/* Allocate a single block of memory which contains
@@ -1333,7 +1333,7 @@ static int decrypt_internal(struct sock *sk, struct sk_buff *skb,
 	sgin = (struct scatterlist *)(mem + aead_size);
 	sgout = sgin + n_sgin;
 	aad = (u8 *)(sgout + n_sgout);
-	iv = aad + TLS_AAD_SPACE_SIZE;
+	iv = aad + tls_ctx->rx.aad_size;
 
 	/* Prepare IV */
 	err = skb_copy_bits(skb, rxm->offset + TLS_HEADER_SIZE,
@@ -1352,7 +1352,7 @@ static int decrypt_internal(struct sock *sk, struct sk_buff *skb,
 
 	/* Prepare sgin */
 	sg_init_table(sgin, n_sgin);
-	sg_set_buf(&sgin[0], aad, TLS_AAD_SPACE_SIZE);
+	sg_set_buf(&sgin[0], aad, tls_ctx->rx.aad_size);
 	err = skb_to_sgvec(skb, &sgin[1],
 			   rxm->offset + tls_ctx->rx.prepend_size,
 			   rxm->full_len - tls_ctx->rx.prepend_size);
@@ -1364,7 +1364,7 @@ static int decrypt_internal(struct sock *sk, struct sk_buff *skb,
 	if (n_sgout) {
 		if (out_iov) {
 			sg_init_table(sgout, n_sgout);
-			sg_set_buf(&sgout[0], aad, TLS_AAD_SPACE_SIZE);
+			sg_set_buf(&sgout[0], aad, tls_ctx->rx.aad_size);
 
 			*chunk = 0;
 			err = tls_setup_from_iter(sk, out_iov, data_len,
@@ -2100,6 +2100,7 @@ int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx)
 		goto free_priv;
 	}
 
+	cctx->aad_size = TLS_AAD_SPACE_SIZE;
 	cctx->prepend_size = TLS_HEADER_SIZE + nonce_size;
 	cctx->tag_size = tag_size;
 	cctx->overhead_size = cctx->prepend_size + cctx->tag_size;