From aa4d426b4d3527d7e166df1a05058c9a4a0f6683 Mon Sep 17 00:00:00 2001 From: Wojtek Kosior Date: Fri, 30 Apr 2021 00:33:56 +0200 Subject: initial/final commit --- .../doc/ssl/SSL_CTX_set_client_cert_cb.pod | 103 +++++++++++++++++++++ 1 file changed, 103 insertions(+) create mode 100644 openssl-1.1.0h/doc/ssl/SSL_CTX_set_client_cert_cb.pod (limited to 'openssl-1.1.0h/doc/ssl/SSL_CTX_set_client_cert_cb.pod') diff --git a/openssl-1.1.0h/doc/ssl/SSL_CTX_set_client_cert_cb.pod b/openssl-1.1.0h/doc/ssl/SSL_CTX_set_client_cert_cb.pod new file mode 100644 index 0000000..aed7d4f --- /dev/null +++ b/openssl-1.1.0h/doc/ssl/SSL_CTX_set_client_cert_cb.pod @@ -0,0 +1,103 @@ +=pod + +=head1 NAME + +SSL_CTX_set_client_cert_cb, SSL_CTX_get_client_cert_cb - handle client certificate callback function + +=head1 SYNOPSIS + + #include + + void SSL_CTX_set_client_cert_cb(SSL_CTX *ctx, int (*client_cert_cb)(SSL *ssl, X509 **x509, EVP_PKEY **pkey)); + int (*SSL_CTX_get_client_cert_cb(SSL_CTX *ctx))(SSL *ssl, X509 **x509, EVP_PKEY **pkey); + int (*client_cert_cb)(SSL *ssl, X509 **x509, EVP_PKEY **pkey); + +=head1 DESCRIPTION + +SSL_CTX_set_client_cert_cb() sets the client_cert_cb() callback, that is +called when a client certificate is requested by a server and no certificate +was yet set for the SSL object. + +When client_cert_cb() is NULL, no callback function is used. + +SSL_CTX_get_client_cert_cb() returns a pointer to the currently set callback +function. + +client_cert_cb() is the application defined callback. If it wants to +set a certificate, a certificate/private key combination must be set +using the B and B arguments and "1" must be returned. The +certificate will be installed into B, see the NOTES and BUGS sections. +If no certificate should be set, "0" has to be returned and no certificate +will be sent. A negative return value will suspend the handshake and the +handshake function will return immediately. L +will return SSL_ERROR_WANT_X509_LOOKUP to indicate, that the handshake was +suspended. The next call to the handshake function will again lead to the call +of client_cert_cb(). It is the job of the client_cert_cb() to store information +about the state of the last call, if required to continue. + +=head1 NOTES + +During a handshake (or renegotiation) a server may request a certificate +from the client. A client certificate must only be sent, when the server +did send the request. + +When a certificate was set using the +L family of functions, +it will be sent to the server. The TLS standard requires that only a +certificate is sent, if it matches the list of acceptable CAs sent by the +server. This constraint is violated by the default behavior of the OpenSSL +library. Using the callback function it is possible to implement a proper +selection routine or to allow a user interaction to choose the certificate to +be sent. + +If a callback function is defined and no certificate was yet defined for the +SSL object, the callback function will be called. +If the callback function returns a certificate, the OpenSSL library +will try to load the private key and certificate data into the SSL +object using the SSL_use_certificate() and SSL_use_private_key() functions. +Thus it will permanently install the certificate and key for this SSL +object. It will not be reset by calling L. +If the callback returns no certificate, the OpenSSL library will not send +a certificate. + +=head1 BUGS + +The client_cert_cb() cannot return a complete certificate chain, it can +only return one client certificate. If the chain only has a length of 2, +the root CA certificate may be omitted according to the TLS standard and +thus a standard conforming answer can be sent to the server. For a +longer chain, the client must send the complete chain (with the option +to leave out the root CA certificate). This can only be accomplished by +either adding the intermediate CA certificates into the trusted +certificate store for the SSL_CTX object (resulting in having to add +CA certificates that otherwise maybe would not be trusted), or by adding +the chain certificates using the +L +function, which is only available for the SSL_CTX object as a whole and that +therefore probably can only apply for one client certificate, making +the concept of the callback function (to allow the choice from several +certificates) questionable. + +Once the SSL object has been used in conjunction with the callback function, +the certificate will be set for the SSL object and will not be cleared +even when L is being called. It is therefore +mandatory to destroy the SSL object using L +and create a new one to return to the previous state. + +=head1 SEE ALSO + +L, L, +L, +L, +L, L + +=head1 COPYRIGHT + +Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved. + +Licensed under the OpenSSL license (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. + +=cut -- cgit v1.2.3