KTLS: Enable KTLS for receiving as well in TLS 1.3

This removes a guard condition that prevents KTLS being enabled for
receiving in TLS 1.3.  Use the correct sequence number and BIO for
receive vs transmit offload.

Co-authored-by: John Baldwin <jhb@FreeBSD.org>
Signed-off-by: Daiki Ueno <dueno@redhat.com>

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from #17942)

CHANGES.md

@@ -24,6 +24,10 @@ OpenSSL 3.1
 
 ### Changes between 3.0 and 3.1 [xx XXX xxxx]
 
+ * Extended Kernel TLS (KTLS) to support TLS 1.3 receive offload.
+
+   *Daiki Ueno, John Baldwin and Dmitry Podgorny*
+
  * Add support for TCP Fast Open (RFC7413) to macOS, Linux, and FreeBSD where
    supported and enabled.
 

ssl/tls13_enc.c

@@ -434,6 +434,7 @@ int tls13_change_cipher_state(SSL *s, int which)
     const EVP_CIPHER *cipher = NULL;
 #if !defined(OPENSSL_NO_KTLS) && defined(OPENSSL_KTLS_TLS13)
     ktls_crypto_info_t crypto_info;
+    void *rl_sequence;
     BIO *bio;
 #endif
 
@@ -688,8 +689,7 @@ int tls13_change_cipher_state(SSL *s, int which)
         s->statem.enc_write_state = ENC_WRITE_STATE_VALID;
 #ifndef OPENSSL_NO_KTLS
 # if defined(OPENSSL_KTLS_TLS13)
-    if (!(which & SSL3_CC_WRITE)
-            || !(which & SSL3_CC_APPLICATION)
+    if (!(which & SSL3_CC_APPLICATION)
             || (s->options & SSL_OP_ENABLE_KTLS) == 0)
         goto skip_ktls;
 
@@ -705,27 +705,37 @@ int tls13_change_cipher_state(SSL *s, int which)
     if (!ktls_check_supported_cipher(s, cipher, ciph_ctx))
         goto skip_ktls;
 
-    bio = s->wbio;
+    if (which & SSL3_CC_WRITE)
+        bio = s->wbio;
+    else
+        bio = s->rbio;
 
     if (!ossl_assert(bio != NULL)) {
         SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
         goto err;
     }
 
     /* All future data will get encrypted by ktls. Flush the BIO or skip ktls */
-    if (BIO_flush(bio) <= 0)
-        goto skip_ktls;
+    if (which & SSL3_CC_WRITE) {
+        if (BIO_flush(bio) <= 0)
+            goto skip_ktls;
+    }
 
     /* configure kernel crypto structure */
-    if (!ktls_configure_crypto(s, cipher, ciph_ctx,
-                               RECORD_LAYER_get_write_sequence(&s->rlayer),
-                               &crypto_info, which & SSL3_CC_WRITE, iv, key,
-                               NULL, 0))
+    if (which & SSL3_CC_WRITE)
+        rl_sequence = RECORD_LAYER_get_write_sequence(&s->rlayer);
+    else
+        rl_sequence = RECORD_LAYER_get_read_sequence(&s->rlayer);
+
+    if (!ktls_configure_crypto(s, cipher, ciph_ctx, rl_sequence, &crypto_info,
+                               which & SSL3_CC_WRITE, iv, key, NULL, 0))
         goto skip_ktls;
 
     /* ktls works with user provided buffers directly */
-    if (BIO_set_ktls(bio, &crypto_info, which & SSL3_CC_WRITE))
-        ssl3_release_write_buffer(s);
+    if (BIO_set_ktls(bio, &crypto_info, which & SSL3_CC_WRITE)) {
+        if (which & SSL3_CC_WRITE)
+            ssl3_release_write_buffer(s);
+    }
 skip_ktls:
 # endif
 #endif

test/sslapitest.c

@@ -1242,7 +1242,7 @@ static int execute_test_ktls(int cis_ktls, int sis_ktls,
 #if defined(OPENSSL_NO_KTLS_RX)
     rx_supported = 0;
 #else
-    rx_supported = (tls_version != TLS1_3_VERSION);
+    rx_supported = 1;
 #endif
     if (!cis_ktls || !rx_supported) {
         if (!TEST_false(BIO_get_ktls_recv(clientssl->rbio)))