p11-kit-remote-proxy: add a PKCS#11 module for remoting

This allows making a PKCS#11-enabled application that doesn't link to
p11-kit to use a remote module easily.

The remote is set up using P11_REMOTE environment variable, for a lack
of a better mechanism to pass data to the PKCS#11 module.

doc/manual/p11-kit-docs.xml

@@ -14,6 +14,7 @@
 	<xi:include href="p11-kit-config.xml"/>
 	<xi:include href="p11-kit-sharing.xml"/>
 	<xi:include href="p11-kit-proxy.xml"/>
+	<xi:include href="p11-kit-remote-proxy.xml"/>
 	<xi:include href="p11-kit-trust.xml"/>
 
 	<chapter xml:id="tools">

doc/manual/p11-kit-remote-proxy.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0"?>
+<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" [
+]>
+<chapter xml:id="remote-proxy">
+	<title>Remote Proxy Module</title>
+
+	<para>While the proxy module exposes the configured modules, the remoting
+	functionality of <literal>p11-kit</literal> often needs to be set up
+	dynamically (while the module for an actual token is selected by the remote
+	end).</para>
+
+	<para>To allow use of the remoting capability for PKCS#11 consumers that don't
+	link to p11-kit, a separate proxy module is provided that can be used in place
+	of an ordinary PKCS#11 module. It proxies the PKCS#11 calls to a remote specified
+	by the <envar>P11_REMOTE</envar> environment variable, using the same syntax as
+	a <literal>remote</literal> module in the configuration file.</para>
+</chapter>

p11-kit/Makefile.am

@@ -28,7 +28,8 @@ MODULE_SRCS = \
 	$(inc_HEADERS)
 
 lib_LTLIBRARIES += \
-	libp11-kit.la
+	libp11-kit.la \
+	p11-kit-remote-proxy.la
 
 libp11_kit_la_CFLAGS = \
 	-DP11_SYSTEM_CONFIG_FILE=\""$(p11_system_config_file)"\" \
@@ -54,6 +55,17 @@ libp11_kit_la_LIBADD = \
 	$(LTLIBINTL) \
 	$(NULL)
 
+p11_kit_remote_proxy_la_SOURCES = \
+	p11-kit/remote-proxy.c
+
+p11_kit_remote_proxy_la_LDFLAGS = \
+	-module \
+	-avoid-version \
+	-export-symbols-regex '^C_GetFunctionList'
+
+p11_kit_remote_proxy_la_LIBADD = \
+	libp11-kit.la
+
 noinst_LTLIBRARIES += \
 	libp11-kit-testable.la
 

p11-kit/p11-kit-1.pc.in

@@ -10,6 +10,7 @@ p11_module_configs=@p11_package_config_modules@
 p11_module_path=@p11_module_path@
 p11_trust_paths=@with_trust_paths@
 proxy_module=@libdir@/p11-kit-proxy.so
+remote_proxy_module=@libdir@/p11-kit-remote-proxy.so
 
 # This is for compatibility. Other packages were using this to determine
 # the directory they should install their module configs to, so override

p11-kit/remote-proxy.c

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2016 Red Hat, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *     * Redistributions of source code must retain the above
+ *       copyright notice, this list of conditions and the
+ *       following disclaimer.
+ *     * Redistributions in binary form must reproduce the
+ *       above copyright notice, this list of conditions and
+ *       the following disclaimer in the documentation and/or
+ *       other materials provided with the distribution.
+ *     * The names of contributors to this software may not be
+ *       used to endorse or promote products derived from this
+ *       software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+ * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * Author: Lubomir Rintel <[email protected]>
+ */
+
+#include "config.h"
+#include "p11-kit.h"
+
+#include <stdlib.h>
+
+CK_RV
+C_GetFunctionList (CK_FUNCTION_LIST_PTR_PTR list)
+{
+	char *remote;
+
+	remote = getenv ("P11_REMOTE");
+	if (remote == NULL)
+		return CKR_ARGUMENTS_BAD;
+
+	*list = p11_kit_module_remote (remote, 0);
+	if (*list == NULL)
+		return CKR_GENERAL_ERROR;
+
+	return CKR_OK;
+}