netdev - [PATCH net-next 06/10] tls: rx: use a define for tag length

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Date:   Thu,  7 Apr 2022 20:38:19 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     davem@...emloft.net, pabeni@...hat.com
Cc:     netdev@...r.kernel.org, borisp@...dia.com,
        john.fastabend@...il.com, daniel@...earbox.net,
        vfedorenko@...ek.ru, Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH net-next 06/10] tls: rx: use a define for tag length

TLS 1.3 has to strip padding, and it starts out 16 bytes
from the end of the record. Make it clear this is because
of the auth tag.

Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
 include/net/tls.h | 1 +
 net/tls/tls_sw.c  | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/net/tls.h b/include/net/tls.h
index f040edc97c50..a01c264e5f15 100644
--- a/include/net/tls.h
+++ b/include/net/tls.h
@@ -64,6 +64,7 @@
 #define TLS_AAD_SPACE_SIZE		13
 
 #define MAX_IV_SIZE			16
+#define TLS_TAG_SIZE			16
 #define TLS_MAX_REC_SEQ_SIZE		8
 
 /* For CCM mode, the full 16-bytes of IV is made of '4' fields of given sizes.
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index eb2e8495aa62..579ccfd011a1 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -136,9 +136,9 @@ static int padding_length(struct tls_prot_info *prot, struct sk_buff *skb)
 
 	/* Determine zero-padding length */
 	if (prot->version == TLS_1_3_VERSION) {
+		int back = TLS_TAG_SIZE + 1;
 		char content_type = 0;
 		int err;
-		int back = 17;
 
 		while (content_type == 0) {
 			if (back > rxm->full_len - prot->prepend_size)
@@ -2496,7 +2496,7 @@ int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx)
 
 	/* Sanity-check the sizes for stack allocations. */
 	if (iv_size > MAX_IV_SIZE || nonce_size > MAX_IV_SIZE ||
-	    rec_seq_size > TLS_MAX_REC_SEQ_SIZE) {
+	    rec_seq_size > TLS_MAX_REC_SEQ_SIZE || tag_size != TLS_TAG_SIZE) {
 		rc = -EINVAL;
 		goto free_priv;
 	}
-- 
2.34.1