Update KTLS documentation

KTLS support has been changed to be off by default, and configuration is
via a single "option" rather two "modes". Documentation is updated
accordingly.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/14799)

3 files changed, 27 insertions, 17 deletions

diff --git a/doc/man3/SSL_CONF_cmd.pod b/doc/man3/SSL_CONF_cmd.pod
index 97ebff047f..3fd1924de6 100644
--- a/doc/man3/SSL_CONF_cmd.pod
+++ b/doc/man3/SSL_CONF_cmd.pod
@@ -524,6 +524,10 @@ B<CANames>: use CA names extension, enabled by
 default. Inverse of B<SSL_OP_DISABLE_TLSEXT_CA_NAMES>: that is,
 B<-CANames> is the same as setting B<SSL_OP_DISABLE_TLSEXT_CA_NAMES>.
 
+B<KTLS>: Enables kernel TLS if support has been compiled in, and it is supported
+by the negotiated ciphersuites and extensions. Equivalent to
+B<SSL_OP_ENABLE_KTLS>.
+
 =item B<VerifyMode>
 
 The B<value> argument is a comma separated list of flags to set.
diff --git a/doc/man3/SSL_CTX_set_mode.pod b/doc/man3/SSL_CTX_set_mode.pod
index a814022d3c..39b5e1906f 100644
--- a/doc/man3/SSL_CTX_set_mode.pod
+++ b/doc/man3/SSL_CTX_set_mode.pod
@@ -105,22 +105,6 @@ Enable asynchronous processing. TLS I/O operations may indicate a retry with
 SSL_ERROR_WANT_ASYNC with this mode set if an asynchronous capable engine is
 used to perform cryptographic operations. See L<SSL_get_error(3)>.
 
-=item SSL_MODE_NO_KTLS_TX
-
-Disable the use of the kernel TLS egress data-path.
-By default kernel TLS is enabled if it is supported by the negotiated ciphersuites
-and extensions and OpenSSL has been compiled with support for it.
-The kernel TLS data-path implements the record layer,
-and the crypto algorithm. The kernel will utilize the best hardware
-available for crypto. Using the kernel data-path should reduce the memory
-footprint of OpenSSL because no buffering is required. Also, the throughput
-should improve because data copy is avoided when user data is encrypted into
-kernel memory instead of the usual encrypt than copy to kernel.
-
-Kernel TLS might not support all the features of OpenSSL. For instance,
-renegotiation, and setting the maximum fragment size is not possible as of
-Linux 4.20.
-
 =item SSL_MODE_DTLS_SCTP_LABEL_LENGTH_BUG
 
 Older versions of OpenSSL had a bug in the computation of the label length
@@ -150,7 +134,6 @@ L<SSL_write(3)>, L<SSL_get_error(3)>
 =head1 HISTORY
 
 SSL_MODE_ASYNC was added in OpenSSL 1.1.0.
-SSL_MODE_NO_KTLS_TX was added in OpenSSL 3.0.
 
 =head1 COPYRIGHT
 
diff --git a/doc/man3/SSL_CTX_set_options.pod b/doc/man3/SSL_CTX_set_options.pod
index 68a1552430..2212e8aca3 100644
--- a/doc/man3/SSL_CTX_set_options.pod
+++ b/doc/man3/SSL_CTX_set_options.pod
@@ -279,6 +279,29 @@ responsible for cleansing all other buffers. Most notably, this
 applies to buffers passed to functions like L<SSL_read(3)>,
 L<SSL_peek(3)> but also like L<SSL_write(3)>.
 
+=item SSL_OP_ENABLE_KTLS
+
+Enable the use of kernel TLS. In order to benefit from kernel TLS OpenSSL must
+have been compiled with support for it, and it must be supported by the
+negotiated ciphersuites and extensions. The specific ciphersuites and extensions
+that are supported may vary by platform and kernel version.
+
+The kernel TLS data-path implements the record layer, and the encryption
+algorithm. The kernel will utilize the best hardware
+available for encryption. Using the kernel data-path should reduce the memory
+footprint of OpenSSL because no buffering is required. Also, the throughput
+should improve because data copy is avoided when user data is encrypted into
+kernel memory instead of the usual encrypt then copy to kernel.
+
+Kernel TLS might not support all the features of OpenSSL. For instance,
+renegotiation, and setting the maximum fragment size is not possible as of
+Linux 4.20.
+
+Note that with kernel TLS enabled some cryptographic operations are performed
+by the kernel directly and not via any available OpenSSL Providers. This might
+be undesirable if, for example, the application requires all cryptographic
+operations to be performed by the FIPS provider.
+
 =back
 
 The following options no longer have any effect but their identifiers are