OPENSSL_s390xcap.pod: list msa9 facility bit (155)

[openssl.git] / doc / man3 / SSL_CTX_set_mode.pod

diff --git a/doc/man3/SSL_CTX_set_mode.pod b/doc/man3/SSL_CTX_set_mode.pod
index e83b591887d12954dea0d4ba72eda8c936e12a5e..f1f6c7a5c88a2a424120b3ad197a4e33e72cc584 100644 (file)
--- a/doc/man3/SSL_CTX_set_mode.pod
+++ b/doc/man3/SSL_CTX_set_mode.pod
@@ -2,14 +2,16 @@
 
 =head1 NAME
 
-SSL_CTX_set_mode, SSL_set_mode, SSL_CTX_get_mode, SSL_get_mode - manipulate SSL engine mode
+SSL_CTX_set_mode, SSL_CTX_clear_mode, SSL_set_mode, SSL_clear_mode, SSL_CTX_get_mode, SSL_get_mode - manipulate SSL engine mode
 
 =head1 SYNOPSIS
 
  #include <openssl/ssl.h>
 
  long SSL_CTX_set_mode(SSL_CTX *ctx, long mode);
+ long SSL_CTX_clear_mode(SSL_CTX *ctx, long mode);
  long SSL_set_mode(SSL *ssl, long mode);
+ long SSL_clear_mode(SSL *ssl, long mode);
 
  long SSL_CTX_get_mode(SSL_CTX *ctx);
  long SSL_get_mode(SSL *ssl);
@@ -18,9 +20,11 @@ SSL_CTX_set_mode, SSL_set_mode, SSL_CTX_get_mode, SSL_get_mode - manipulate SSL
 
 SSL_CTX_set_mode() adds the mode set via bitmask in B<mode> to B<ctx>.
 Options already set before are not cleared.
+SSL_CTX_clear_mode() removes the mode set via bitmask in B<mode> from B<ctx>.
 
 SSL_set_mode() adds the mode set via bitmask in B<mode> to B<ssl>.
 Options already set before are not cleared.
+SSL_clear_mode() removes the mode set via bitmask in B<mode> from B<ssl>.
 
 SSL_CTX_get_mode() returns the mode set for B<ctx>.
 
@@ -51,16 +55,31 @@ non-blocking write().
 
 =item SSL_MODE_AUTO_RETRY
 
-Never bother the application with retries if the transport is blocking.
-If a renegotiation take place during normal operation, a
-L<SSL_read_ex(3)>, L<SSL_read(3)>, L<SSL_write_ex(3)> or L<SSL_write(3)> would
-return with a failure and indicate the need to retry with SSL_ERROR_WANT_READ.
+During normal operations, non-application data records might need to be sent or
+received that the application is not aware of.
+If a non-application data record was processed,
+L<SSL_read_ex(3)> and L<SSL_read(3)> can return with a failure and indicate the
+need to retry with B<SSL_ERROR_WANT_READ>.
+If such a non-application data record was processed, the flag
+B<SSL_MODE_AUTO_RETRY> causes it to try to process the next record instead of
+returning.
+
 In a non-blocking environment applications must be prepared to handle
 incomplete read/write operations.
+Setting B<SSL_MODE_AUTO_RETRY> for a non-blocking B<BIO> will process
+non-application data records until either no more data is available or
+an application data record has been processed.
+
 In a blocking environment, applications are not always prepared to
-deal with read/write operations returning without success report. The
-flag SSL_MODE_AUTO_RETRY will cause read/write operations to only
-return after the handshake and successful completion.
+deal with the functions returning intermediate reports such as retry
+requests, and setting the B<SSL_MODE_AUTO_RETRY> flag will cause the functions
+to only return after successfully processing an application data record or a
+failure.
+
+Turning off B<SSL_MODE_AUTO_RETRY> can be useful with blocking B<BIO>s in case
+they are used in combination with something like select() or poll().
+Otherwise the call to SSL_read() or SSL_read_ex() might hang when a
+non-application record was sent and no application data was sent.
 
 =item SSL_MODE_RELEASE_BUFFERS
 
@@ -86,8 +105,36 @@ 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
+used for computing the endpoint-pair shared secret. The bug was that the
+terminating zero was included in the length of the label. Setting this option
+enables this behaviour to allow interoperability with such broken
+implementations. Please note that setting this option breaks interoperability
+with correct implementations. This option only applies to DTLS over SCTP.
+
 =back
 
+All modes are off by default except for SSL_MODE_AUTO_RETRY which is on by
+default since 1.1.1.
+
 =head1 RETURN VALUES
 
 SSL_CTX_set_mode() and SSL_set_mode() return the new mode bitmask
@@ -102,13 +149,14 @@ L<SSL_write(3)>, L<SSL_get_error(3)>
 
 =head1 HISTORY
 
-SSL_MODE_ASYNC was first added to OpenSSL 1.1.0.
+SSL_MODE_ASYNC was added in OpenSSL 1.1.0.
+SSL_MODE_NO_KTLS_TX was added in OpenSSL 3.0.
 
 =head1 COPYRIGHT
 
-Copyright 2001-2016 The OpenSSL Project Authors. All Rights Reserved.
+Copyright 2001-2018 The OpenSSL Project Authors. All Rights Reserved.
 
-Licensed under the OpenSSL license (the "License").  You may not use
+Licensed under the Apache License 2.0 (the "License").  You may not use
 this file except in compliance with the License.  You can obtain a copy
 in the file LICENSE in the source distribution or at
 L<https://www.openssl.org/source/license.html>.