[PATCH] net/tls: Fix authentication failure in CCM mode

[Tianjia Zhang]

When the TLS cipher suite uses CCM mode, including AES CCM and
SM4 CCM, the first byte of the B0 block is flags, and the real
IV starts from the second byte. The XOR operation of the IV and
rec_seq should be skip this byte, that is, add the iv_offset.

Fixes: f295b3ae9f59 ("net/tls: Add support of AES128-CCM based ciphers")
Signed-off-by: Tianjia Zhang <tianjia.zhang@xxxxxxxxxxxxxxxxx>
Cc: Vakul Garg <vakul.garg@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v5.2+
---
 net/tls/tls_sw.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index d3e7ff90889e..dfe623a4e72f 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -521,7 +521,7 @@ static int tls_do_encryption(struct sock *sk,
 	memcpy(&rec->iv_data[iv_offset], tls_ctx->tx.iv,
 	       prot->iv_size + prot->salt_size);
 
-	xor_iv_with_seq(prot, rec->iv_data, tls_ctx->tx.rec_seq);
+	xor_iv_with_seq(prot, rec->iv_data + iv_offset, tls_ctx->tx.rec_seq);
 
 	sge->offset += prot->prepend_size;
 	sge->length -= prot->prepend_size;
@@ -1499,7 +1499,7 @@ static int decrypt_internal(struct sock *sk, struct sk_buff *skb,
 	else
 		memcpy(iv + iv_offset, tls_ctx->rx.iv, prot->salt_size);
 
-	xor_iv_with_seq(prot, iv, tls_ctx->rx.rec_seq);
+	xor_iv_with_seq(prot, iv + iv_offset, tls_ctx->rx.rec_seq);
 
 	/* Prepare AAD */
 	tls_make_aad(aad, rxm->full_len - prot->overhead_size +
-- 
2.32.0