net/tls: make sure tls offload sets salt_size

Recent changes made to remove AES constants started using protocol
aware salt_size. ctx->prot_info's salt_size is filled in tls sw case,
but not in tls offload mode, and was working so far because of the
hard coded value was used.

Fixes: 6942a284 ("net/tls: make inline helpers protocol-aware")
Signed-off-by: Rohit Maheshwari <rohitm@chelsio.com>
Link: https://lore.kernel.org/r/20201201090752.27355-1-rohitm@chelsio.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/tls/tls_device.c

@@ -998,7 +998,7 @@ static void tls_device_attach(struct tls_context *ctx, struct sock *sk,
 
 int tls_set_device_offload(struct sock *sk, struct tls_context *ctx)
 {
-	u16 nonce_size, tag_size, iv_size, rec_seq_size;
+	u16 nonce_size, tag_size, iv_size, rec_seq_size, salt_size;
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	struct tls_prot_info *prot = &tls_ctx->prot_info;
 	struct tls_record_info *start_marker_record;
@@ -1039,6 +1039,7 @@ int tls_set_device_offload(struct sock *sk, struct tls_context *ctx)
 		iv_size = TLS_CIPHER_AES_GCM_128_IV_SIZE;
 		iv = ((struct tls12_crypto_info_aes_gcm_128 *)crypto_info)->iv;
 		rec_seq_size = TLS_CIPHER_AES_GCM_128_REC_SEQ_SIZE;
+		salt_size = TLS_CIPHER_AES_GCM_128_SALT_SIZE;
 		rec_seq =
 		 ((struct tls12_crypto_info_aes_gcm_128 *)crypto_info)->rec_seq;
 		break;
@@ -1059,6 +1060,7 @@ int tls_set_device_offload(struct sock *sk, struct tls_context *ctx)
 	prot->tag_size = tag_size;
 	prot->overhead_size = prot->prepend_size + prot->tag_size;
 	prot->iv_size = iv_size;
+	prot->salt_size = salt_size;
 	ctx->tx.iv = kmalloc(iv_size + TLS_CIPHER_AES_GCM_128_SALT_SIZE,
 			     GFP_KERNEL);
 	if (!ctx->tx.iv) {