Adding upstream version 3.8.5.upstream/3.8.5

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 317 insertions, 0 deletions

diff --git a/src/postscreen/postscreen_starttls.c b/src/postscreen/postscreen_starttls.c
new file mode 100644
index 0000000..4036a3d
--- /dev/null
+++ b/src/postscreen/postscreen_starttls.c
@@ -0,0 +1,317 @@
+/*++
+/* NAME
+/*	postscreen_starttls 3
+/* SUMMARY
+/*	postscreen TLS proxy support
+/* SYNOPSIS
+/*	#include <postscreen.h>
+/*
+/*	int	psc_starttls_open(state, resume_event)
+/*	PSC_STATE *state;
+/*	void	(*resume_event)(int unused_event, char *context);
+/* DESCRIPTION
+/*	This module inserts the tlsproxy(8) proxy between the
+/*	postscreen(8) server and the remote SMTP client. The entire
+/*	process happens in the background, including notification
+/*	of completion to the remote SMTP client and to the calling
+/*	application.
+/*
+/*	Before calling psc_starttls_open() the caller must turn off
+/*	all pending timer and I/O event requests on the SMTP client
+/*	stream.
+/*
+/*	psc_starttls_open() starts the first transaction in the
+/*	tlsproxy(8) hand-off protocol, and sets up event handlers
+/*	for the successive protocol stages.
+/*
+/*	Upon completion, the event handlers call resume_event()
+/*	which must reset the SMTP helo/sender/etc. state when the
+/*	PSC_STATE_FLAG_USING_TLS is set, and set up timer and read
+/*	event requests to receive the next SMTP command.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*
+/*	Wietse Venema
+/*	Google, Inc.
+/*	111 8th Avenue
+/*	New York, NY 10011, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <mymalloc.h>
+#include <connect.h>
+#include <stringops.h>			/* concatenate() */
+#include <vstring.h>
+
+/* Global library. */
+
+#include <mail_params.h>
+#include <mail_proto.h>
+
+/* TLS library. */
+
+#include <tls_proxy.h>
+
+/* Application-specific. */
+
+#include <postscreen.h>
+
+ /*
+  * For now, this code is built into the postscreen(8) daemon. In the future
+  * it may be abstracted into a reusable library module for use by other
+  * event-driven programs (perhaps smtp-source and smtp-sink).
+  */
+
+ /*
+  * Transient state for the postscreen(8)-to-tlsproxy(8) hand-off protocol.
+  */
+typedef struct {
+    VSTREAM *tlsproxy_stream;		/* hand-off negotiation */
+    EVENT_NOTIFY_FN resume_event;	/* call-back handler */
+    PSC_STATE *smtp_state;		/* SMTP session state */
+} PSC_STARTTLS;
+
+#define TLSPROXY_INIT_TIMEOUT		10
+
+static char *psc_tlsp_service = 0;
+
+/* Resume the dummy SMTP engine after an event handling error */
+
+#define PSC_STARTTLS_EVENT_ERR_RESUME_RETURN() do { \
+	event_disable_readwrite(vstream_fileno(tlsproxy_stream)); \
+	PSC_STARTTLS_EVENT_RESUME_RETURN(starttls_state); \
+    } while (0);
+
+/* Resume the dummy SMTP engine, possibly after swapping streams */
+
+#define PSC_STARTTLS_EVENT_RESUME_RETURN(starttls_state) do { \
+	vstream_fclose(tlsproxy_stream); \
+	starttls_state->resume_event(event, (void *) smtp_state); \
+	myfree((void *) starttls_state); \
+	return; \
+    } while (0)
+
+/* psc_starttls_finish - complete negotiation with TLS proxy */
+
+static void psc_starttls_finish(int event, void *context)
+{
+    const char *myname = "psc_starttls_finish";
+    PSC_STARTTLS *starttls_state = (PSC_STARTTLS *) context;
+    PSC_STATE *smtp_state = starttls_state->smtp_state;
+    VSTREAM *tlsproxy_stream = starttls_state->tlsproxy_stream;
+    int     status;
+
+    if (msg_verbose)
+	msg_info("%s: send client handle on proxy socket %d"
+		 " for smtp socket %d from [%s]:%s flags=%s",
+		 myname, vstream_fileno(tlsproxy_stream),
+		 vstream_fileno(smtp_state->smtp_client_stream),
+		 smtp_state->smtp_client_addr, smtp_state->smtp_client_port,
+		 psc_print_state_flags(smtp_state->flags, myname));
+
+    /*
+     * We leave read-event notification enabled on the postscreen to TLS
+     * proxy stream, to avoid two kqueue/epoll/etc. system calls: one here,
+     * and one when resuming the dummy SMTP engine.
+     */
+    if (event != EVENT_TIME)
+	event_cancel_timer(psc_starttls_finish, (void *) starttls_state);
+
+    /*
+     * Receive the "TLS is available" indication.
+     * 
+     * This may seem out of order, but we must have a read transaction between
+     * sending the request attributes and sending the SMTP client file
+     * descriptor. We can't assume UNIX-domain socket semantics here.
+     */
+    if (event != EVENT_READ
+	|| attr_scan(tlsproxy_stream, ATTR_FLAG_STRICT,
+		     RECV_ATTR_INT(MAIL_ATTR_STATUS, &status),
+		     ATTR_TYPE_END) != 1 || status == 0) {
+
+	/*
+	 * The TLS proxy reports that the TLS engine is not available (due to
+	 * configuration error, or other causes).
+	 */
+	msg_warn("%s receiving status from %s service",
+	     event == EVENT_TIME ? "timeout" : "problem", psc_tlsp_service);
+	PSC_SEND_REPLY(smtp_state,
+		    "454 4.7.0 TLS not available due to local problem\r\n");
+	PSC_STARTTLS_EVENT_ERR_RESUME_RETURN();
+    }
+
+    /*
+     * Send the remote SMTP client file descriptor.
+     */
+    else if (LOCAL_SEND_FD(vstream_fileno(tlsproxy_stream),
+		      vstream_fileno(smtp_state->smtp_client_stream)) < 0) {
+
+	/*
+	 * Some error: drop the TLS proxy stream.
+	 */
+	msg_warn("problem sending file handle to %s service", psc_tlsp_service);
+	PSC_SEND_REPLY(smtp_state,
+		    "454 4.7.0 TLS not available due to local problem\r\n");
+	PSC_STARTTLS_EVENT_ERR_RESUME_RETURN();
+    }
+
+    /*
+     * After we send the plaintext 220 greeting, the client-side TLS engine
+     * is supposed to talk first, then the server-side TLS engine. However,
+     * postscreen(8) will not participate in that conversation.
+     */
+    else {
+	PSC_SEND_REPLY(smtp_state, "220 2.0.0 Ready to start TLS\r\n");
+
+	/*
+	 * Swap the SMTP client stream and the TLS proxy stream, and close
+	 * the direct connection to the SMTP client. The TLS proxy will talk
+	 * directly to the SMTP client, and once the TLS handshake is
+	 * completed, the TLS proxy will talk plaintext to postscreen(8).
+	 * 
+	 * Swap the file descriptors from under the VSTREAM so that we don't
+	 * have to worry about loss of user-configurable VSTREAM attributes.
+	 */
+	vstream_fpurge(smtp_state->smtp_client_stream, VSTREAM_PURGE_BOTH);
+	vstream_control(smtp_state->smtp_client_stream,
+			CA_VSTREAM_CTL_SWAP_FD(tlsproxy_stream),
+			CA_VSTREAM_CTL_END);
+	smtp_state->flags |= PSC_STATE_FLAG_USING_TLS;
+	PSC_STARTTLS_EVENT_RESUME_RETURN(starttls_state);
+    }
+}
+
+/* psc_starttls_first - start negotiation with TLS proxy */
+
+static void psc_starttls_first(int event, void *context)
+{
+    const char *myname = "psc_starttls_first";
+    PSC_STARTTLS *starttls_state = (PSC_STARTTLS *) context;
+    PSC_STATE *smtp_state = starttls_state->smtp_state;
+    VSTREAM *tlsproxy_stream = starttls_state->tlsproxy_stream;
+    static VSTRING *remote_endpt = 0;
+
+    if (msg_verbose)
+	msg_info("%s: receive server protocol on proxy socket %d"
+		 " for smtp socket %d from [%s]:%s flags=%s",
+		 myname, vstream_fileno(tlsproxy_stream),
+		 vstream_fileno(smtp_state->smtp_client_stream),
+		 smtp_state->smtp_client_addr, smtp_state->smtp_client_port,
+		 psc_print_state_flags(smtp_state->flags, myname));
+
+    /*
+     * We leave read-event notification enabled on the postscreen to TLS
+     * proxy stream, to avoid two kqueue/epoll/etc. system calls: one here,
+     * and one when resuming the dummy SMTP engine.
+     */
+    if (event != EVENT_TIME)
+	event_cancel_timer(psc_starttls_first, (void *) starttls_state);
+
+    /*
+     * Receive and verify the server protocol.
+     */
+    if (event != EVENT_READ
+	|| attr_scan(tlsproxy_stream, ATTR_FLAG_STRICT,
+		 RECV_ATTR_STREQ(MAIL_ATTR_PROTO, MAIL_ATTR_PROTO_TLSPROXY),
+		     ATTR_TYPE_END) != 0) {
+	msg_warn("%s receiving %s attribute from %s service: %m",
+		 event == EVENT_TIME ? "timeout" : "problem",
+		 MAIL_ATTR_PROTO, psc_tlsp_service);
+	PSC_SEND_REPLY(smtp_state,
+		    "454 4.7.0 TLS not available due to local problem\r\n");
+	PSC_STARTTLS_EVENT_ERR_RESUME_RETURN();
+    }
+
+    /*
+     * Send the data attributes now, and send the client file descriptor in a
+     * later transaction. We report all errors asynchronously, to avoid
+     * having to maintain multiple error delivery paths.
+     * 
+     * XXX The formatted endpoint should be a state member. Then, we can
+     * simplify all the format strings throughout the program.
+     */
+    if (remote_endpt == 0)
+	remote_endpt = vstring_alloc(20);
+    vstring_sprintf(remote_endpt, "[%s]:%s", smtp_state->smtp_client_addr,
+		    smtp_state->smtp_client_port);
+    attr_print(tlsproxy_stream, ATTR_FLAG_NONE,
+	       SEND_ATTR_STR(TLS_ATTR_REMOTE_ENDPT, STR(remote_endpt)),
+	       SEND_ATTR_INT(TLS_ATTR_FLAGS, TLS_PROXY_FLAG_ROLE_SERVER),
+	       SEND_ATTR_INT(TLS_ATTR_TIMEOUT, psc_normal_cmd_time_limit),
+	       SEND_ATTR_INT(TLS_ATTR_TIMEOUT, psc_normal_cmd_time_limit),
+	       SEND_ATTR_STR(TLS_ATTR_SERVERID, MAIL_SERVICE_SMTPD),	/* XXX */
+	       ATTR_TYPE_END);
+    if (vstream_fflush(tlsproxy_stream) != 0) {
+	msg_warn("error sending request to %s service: %m", psc_tlsp_service);
+	PSC_SEND_REPLY(smtp_state,
+		    "454 4.7.0 TLS not available due to local problem\r\n");
+	PSC_STARTTLS_EVENT_ERR_RESUME_RETURN();
+    }
+
+    /*
+     * Set up a read event for the next phase of the TLS proxy handshake.
+     */
+    PSC_READ_EVENT_REQUEST(vstream_fileno(tlsproxy_stream), psc_starttls_finish,
+			   (void *) starttls_state, TLSPROXY_INIT_TIMEOUT);
+}
+
+/* psc_starttls_open - open negotiations with TLS proxy */
+
+void    psc_starttls_open(PSC_STATE *smtp_state, EVENT_NOTIFY_FN resume_event)
+{
+    const char *myname = "psc_starttls_open";
+    PSC_STARTTLS *starttls_state;
+    VSTREAM *tlsproxy_stream;
+    int     fd;
+
+    if (psc_tlsp_service == 0) {
+	psc_tlsp_service = concatenate(MAIL_CLASS_PRIVATE "/",
+				       var_tlsproxy_service, (char *) 0);
+    }
+
+    /*
+     * Connect to the tlsproxy(8) daemon. We report all errors
+     * asynchronously, to avoid having to maintain multiple delivery paths.
+     */
+    if ((fd = LOCAL_CONNECT(psc_tlsp_service, NON_BLOCKING, 1)) < 0) {
+	msg_warn("connect to %s service: %m", psc_tlsp_service);
+	PSC_SEND_REPLY(smtp_state,
+		    "454 4.7.0 TLS not available due to local problem\r\n");
+	event_request_timer(resume_event, (void *) smtp_state, 0);
+	return;
+    }
+    if (msg_verbose)
+	msg_info("%s: connecting to proxy socket %d"
+		 " for smtp socket %d from [%s]:%s flags=%s",
+		 myname, fd, vstream_fileno(smtp_state->smtp_client_stream),
+		 smtp_state->smtp_client_addr, smtp_state->smtp_client_port,
+		 psc_print_state_flags(smtp_state->flags, myname));
+
+    tlsproxy_stream = vstream_fdopen(fd, O_RDWR);
+    vstream_control(tlsproxy_stream,
+		    VSTREAM_CTL_PATH, psc_tlsp_service,
+		    VSTREAM_CTL_END);
+
+    /*
+     * Set up a read event for the next phase of the TLS proxy handshake.
+     */
+    starttls_state = (PSC_STARTTLS *) mymalloc(sizeof(*starttls_state));
+    starttls_state->tlsproxy_stream = tlsproxy_stream;
+    starttls_state->resume_event = resume_event;
+    starttls_state->smtp_state = smtp_state;
+    PSC_READ_EVENT_REQUEST(vstream_fileno(tlsproxy_stream), psc_starttls_first,
+			   (void *) starttls_state, TLSPROXY_INIT_TIMEOUT);
+}