diff -up openssh-7.4p1/monitor_wrap.c.audit-race openssh-7.4p1/monitor_wrap.c

--- openssh-7.4p1/monitor_wrap.c.audit-race	2017-02-09 14:07:56.870994116 +0100

+++ openssh-7.4p1/monitor_wrap.c	2017-02-09 14:07:56.874994112 +0100

@@ -1107,4 +1107,48 @@ mm_audit_destroy_sensitive_data(const ch

 	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUDIT_SERVER_KEY_FREE, &m);

 	buffer_free(&m);

 }

+

+int mm_forward_audit_messages(int fdin)

+{

+	u_char buf[4];

+	u_int blen, msg_len;

+	Buffer m;

+	int ret = 0;

+

+	debug3("%s: entering", __func__);

+	buffer_init(&m);

+	do {

+		blen = atomicio(read, fdin, buf, sizeof(buf));

+		if (blen == 0) /* closed pipe */

+			break;

+		if (blen != sizeof(buf)) {

+			error("%s: Failed to read the buffer from child", __func__);

+			ret = -1;

+			break;

+		}

+

+		msg_len = get_u32(buf);

+		if (msg_len > 256 * 1024)

+			fatal("%s: read: bad msg_len %d", __func__, msg_len);

+		buffer_clear(&m);

+		buffer_append_space(&m, msg_len);

+		if (atomicio(read, fdin, buffer_ptr(&m), msg_len) != msg_len) {

+			error("%s: Failed to read the the buffer content from the child", __func__);

+			ret = -1;

+			break;

+		}

+		if (atomicio(vwrite, pmonitor->m_recvfd, buf, blen) != blen || 

+		    atomicio(vwrite, pmonitor->m_recvfd, buffer_ptr(&m), msg_len) != msg_len) {

+			error("%s: Failed to write the message to the monitor", __func__);

+			ret = -1;

+			break;

+		}

+	} while (1);

+	buffer_free(&m);

+	return ret;

+}

+void mm_set_monitor_pipe(int fd)

+{

+	pmonitor->m_recvfd = fd;

+}

 #endif /* SSH_AUDIT_EVENTS */

diff -up openssh-7.4p1/monitor_wrap.h.audit-race openssh-7.4p1/monitor_wrap.h

--- openssh-7.4p1/monitor_wrap.h.audit-race	2017-02-09 14:07:56.870994116 +0100

+++ openssh-7.4p1/monitor_wrap.h	2017-02-09 14:07:56.874994112 +0100

@@ -80,6 +80,8 @@ void mm_audit_unsupported_body(int);

 void mm_audit_kex_body(int, char *, char *, char *, char *, pid_t, uid_t);

 void mm_audit_session_key_free_body(int, pid_t, uid_t);

 void mm_audit_destroy_sensitive_data(const char *, pid_t, uid_t);

+int mm_forward_audit_messages(int);

+void mm_set_monitor_pipe(int);

 #endif

 struct Session;

diff -up openssh-7.4p1/session.c.audit-race openssh-7.4p1/session.c

--- openssh-7.4p1/session.c.audit-race	2017-02-09 14:07:56.871994115 +0100

+++ openssh-7.4p1/session.c	2017-02-09 14:09:44.710893783 +0100

@@ -162,6 +162,10 @@ static Session *sessions = NULL;

 login_cap_t *lc;

 #endif

+#ifdef SSH_AUDIT_EVENTS

+int paudit[2];

+#endif

+

 static int is_child = 0;

 static int in_chroot = 0;

 static int have_dev_log = 1;

@@ -289,6 +293,8 @@ xauth_valid_string(const char *s)

 	return 1;

 }

+void child_destory_sensitive_data();

+

 #define USE_PIPES 1

 /*

  * This is called to fork and execute a command when we have no tty.  This

@@ -424,6 +430,8 @@ do_exec_no_pty(Session *s, const char *c

 		cray_init_job(s->pw); /* set up cray jid and tmpdir */

 #endif

+		child_destory_sensitive_data();

+

 		/* Do processing for the child (exec command etc). */

 		do_child(s, command);

 		/* NOTREACHED */

@@ -547,6 +555,9 @@ do_exec_pty(Session *s, const char *comm

 		/* Close the extra descriptor for the pseudo tty. */

 		close(ttyfd);

+		/* Do this early, so we will not block large MOTDs */

+		child_destory_sensitive_data();

+

 		/* record login, etc. similar to login(1) */

 #ifdef _UNICOS

 		cray_init_job(s->pw); /* set up cray jid and tmpdir */

@@ -717,6 +728,8 @@ do_exec(Session *s, const char *command)

 	}

 	if (s->command != NULL && s->ptyfd == -1)

 		s->command_handle = PRIVSEP(audit_run_command(s->command));

+	if (pipe(paudit) < 0)

+		fatal("pipe: %s", strerror(errno));

 #endif

 	if (s->ttyfd != -1)

 		ret = do_exec_pty(s, command);

@@ -732,6 +745,20 @@ do_exec(Session *s, const char *command)

 	 */

 	buffer_clear(&loginmsg);

+#ifdef SSH_AUDIT_EVENTS

+	close(paudit[1]);

+	if (use_privsep && ret == 0) {

+		/*

+		 * Read the audit messages from forked child and send them

+		 * back to monitor. We don't want to communicate directly,

+		 * because the messages might get mixed up.

+		 * Continue after the pipe gets closed (all messages sent).

+		 */

+		ret = mm_forward_audit_messages(paudit[0]);

+	}

+	close(paudit[0]);

+#endif /* SSH_AUDIT_EVENTS */

+

 	return ret;

 }

@@ -1542,6 +1569,33 @@ child_close_fds(void)

 	endpwent();

 }

+void

+child_destory_sensitive_data()

+{

+#ifdef SSH_AUDIT_EVENTS

+	int pparent = paudit[1];

+	close(paudit[0]);

+	/* Hack the monitor pipe to avoid race condition with parent */

+	if (use_privsep)

+		mm_set_monitor_pipe(pparent);

+#endif

+

+	/* remove hostkey from the child's memory */

+	destroy_sensitive_data(use_privsep);

+	/*

+	 * We can audit this, because we hacked the pipe to direct the

+	 * messages over postauth child. But this message requires answer

+	 * which we can't do using one-way pipe.

+	 */

+	packet_destroy_all(0, 1);

+

+#ifdef SSH_AUDIT_EVENTS

+	/* Notify parent that we are done */

+	close(pparent);

+#endif

+

+}

+

 /*

  * Performs common processing for the child, such as setting up the

  * environment, closing extra file descriptors, setting the user and group

@@ -1558,12 +1612,6 @@ do_child(Session *s, const char *command

 	struct passwd *pw = s->pw;

 	int r = 0;

-	/* remove hostkey from the child's memory */

-	destroy_sensitive_data(1);

-	/* Don't audit this - both us and the parent would be talking to the

-	   monitor over a single socket, with no synchronization. */

-	packet_destroy_all(0, 1);

-

 	/* Force a password change */

 	if (s->authctxt->force_pwchange) {

 		do_setusercontext(pw);