net/tls: support SM4 CCM algorithm

The IV of CCM mode has special requirements, this patch supports CCM
mode of SM4 algorithm.
Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/tls.h

@@ -66,7 +66,7 @@
 #define MAX_IV_SIZE			16
 #define TLS_MAX_REC_SEQ_SIZE		8
 
-/* For AES-CCM, the full 16-bytes of IV is made of '4' fields of given sizes.
+/* For CCM mode, the full 16-bytes of IV is made of '4' fields of given sizes.
  *
  * IV[16] = b0[1] || implicit nonce[4] || explicit nonce[8] || length[3]
  *
@@ -74,6 +74,7 @@
  * Hence b0 contains (3 - 1) = 2.
  */
 #define TLS_AES_CCM_IV_B0_BYTE		2
+#define TLS_SM4_CCM_IV_B0_BYTE		2
 
 #define __TLS_INC_STATS(net, field)				\
 	__SNMP_INC_STATS((net)->mib.tls_statistics, field)

net/tls/tls_sw.c

@@ -498,9 +498,15 @@ static int tls_do_encryption(struct sock *sk,
 	int rc, iv_offset = 0;
 
 	/* For CCM based ciphers, first byte of IV is a constant */
-	if (prot->cipher_type == TLS_CIPHER_AES_CCM_128) {
+	switch (prot->cipher_type) {
+	case TLS_CIPHER_AES_CCM_128:
 		rec->iv_data[0] = TLS_AES_CCM_IV_B0_BYTE;
 		iv_offset = 1;
+		break;
+	case TLS_CIPHER_SM4_CCM:
+		rec->iv_data[0] = TLS_SM4_CCM_IV_B0_BYTE;
+		iv_offset = 1;
+		break;
 	}
 
 	memcpy(&rec->iv_data[iv_offset], tls_ctx->tx.iv,
@@ -1457,10 +1463,16 @@ static int decrypt_internal(struct sock *sk, struct sk_buff *skb,
 	aad = (u8 *)(sgout + n_sgout);
 	iv = aad + prot->aad_size;
 
-	/* For CCM based ciphers, first byte of nonce+iv is always '2' */
-	if (prot->cipher_type == TLS_CIPHER_AES_CCM_128) {
-		iv[0] = 2;
+	/* For CCM based ciphers, first byte of nonce+iv is a constant */
+	switch (prot->cipher_type) {
+	case TLS_CIPHER_AES_CCM_128:
+		iv[0] = TLS_AES_CCM_IV_B0_BYTE;
 		iv_offset = 1;
+		break;
+	case TLS_CIPHER_SM4_CCM:
+		iv[0] = TLS_SM4_CCM_IV_B0_BYTE;
+		iv_offset = 1;
+		break;
 	}
 
 	/* Prepare IV */