[PATCH 5.4 69/70] net/tls: Fix authentication failure in CCM mode

[Greg Kroah-Hartman]

From: Tianjia Zhang <tianjia.zhang@xxxxxxxxxxxxxxxxx>

commit 5961060692f8b17cd2080620a3d27b95d2ae05ca upstream.

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+
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/tls/tls_sw.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -512,7 +512,7 @@ static int tls_do_encryption(struct sock
 	memcpy(&rec->iv_data[iv_offset], tls_ctx->tx.iv,
 	       prot->iv_size + prot->salt_size);
 
-	xor_iv_with_seq(prot->version, rec->iv_data, tls_ctx->tx.rec_seq);
+	xor_iv_with_seq(prot->version, rec->iv_data + iv_offset, tls_ctx->tx.rec_seq);
 
 	sge->offset += prot->prepend_size;
 	sge->length -= prot->prepend_size;
@@ -1483,7 +1483,7 @@ static int decrypt_internal(struct sock
 	else
 		memcpy(iv + iv_offset, tls_ctx->rx.iv, prot->salt_size);
 
-	xor_iv_with_seq(prot->version, iv, tls_ctx->rx.rec_seq);
+	xor_iv_with_seq(prot->version, iv + iv_offset, tls_ctx->rx.rec_seq);
 
 	/* Prepare AAD */
 	tls_make_aad(aad, rxm->full_len - prot->overhead_size +