From 2d34205dab08ede9b0676efa57647fc49e6decbe Mon Sep 17 00:00:00 2001
From: "djm@openbsd.org" <djm@openbsd.org>
Date: Wed, 26 Jul 2023 23:06:00 +0000
Subject: [PATCH] upstream: make ssh -f (fork after authentication) work
 properly in

multiplexed cases (inc. ControlPersist). bz3589 bz3589 Based on patches by
Peter Chubb; ok dtucker@

OpenBSD-Commit-ID: a7a2976a54b93e6767dc846b85647e6ec26969ac
---
 mux.c | 16 +++++++++++-----
 ssh.c | 17 +++++++++++------
 2 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/mux.c b/mux.c
index 416fef8eb..66d969830 100644
--- a/mux.c
+++ b/mux.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: mux.c,v 1.97 2023/06/20 23:59:33 djm Exp $ */
+/* $OpenBSD: mux.c,v 1.98 2023/07/26 23:06:00 djm Exp $ */
 /*
  * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org>
  *
@@ -1881,7 +1881,7 @@ mux_client_request_session(int fd)
 	const char *term = NULL;
 	u_int i, echar, rid, sid, esid, exitval, type, exitval_seen;
 	extern char **environ;
-	int r, rawmode;
+	int r, rawmode = 0;
 
 	debug3_f("entering");
 
@@ -1991,9 +1991,15 @@ mux_client_request_session(int fd)
 	ssh_signal(SIGTERM, control_client_sighandler);
 	ssh_signal(SIGWINCH, control_client_sigrelay);
 
-	rawmode = tty_flag;
-	if (tty_flag)
-		enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
+	if (options.fork_after_authentication)
+		daemon(1, 1);
+	else {
+		rawmode = tty_flag;
+		if (tty_flag) {
+			enter_raw_mode(
+			    options.request_tty == REQUEST_TTY_FORCE);
+		}
+	}
 
 	/*
 	 * Stick around until the controlee closes the client_fd.
diff --git a/ssh.c b/ssh.c
index c8fcfb2b9..caf3c692c 100644
--- a/ssh.c
+++ b/ssh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.592 2023/07/17 05:41:53 jmc Exp $ */
+/* $OpenBSD: ssh.c,v 1.593 2023/07/26 23:06:00 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -130,10 +130,11 @@ int tty_flag = 0;
  * Flag indicating that the current process should be backgrounded and
  * a new mux-client launched in the foreground for ControlPersist.
  */
-int need_controlpersist_detach = 0;
+static int need_controlpersist_detach = 0;
 
 /* Copies of flags for ControlPersist foreground mux-client */
-int ostdin_null_flag, osession_type, otty_flag, orequest_tty;
+static int ostdin_null_flag, osession_type, otty_flag, orequest_tty;
+static int ofork_after_authentication;
 
 /*
  * General data structure for command line options and options configurable
@@ -1757,11 +1758,15 @@ control_persist_detach(void)
 		/* Child: master process continues mainloop */
 		break;
 	default:
-		/* Parent: set up mux client to connect to backgrounded master */
+		/*
+		 * Parent: set up mux client to connect to backgrounded
+		 * master.
+		 */
 		debug2_f("background process is %ld", (long)pid);
 		options.stdin_null = ostdin_null_flag;
 		options.request_tty = orequest_tty;
 		tty_flag = otty_flag;
+		options.fork_after_authentication = ofork_after_authentication;
 		options.session_type = osession_type;
 		close(muxserver_sock);
 		muxserver_sock = -1;
@@ -2173,11 +2178,11 @@ ssh_session2(struct ssh *ssh, const struct ssh_conn_info *cinfo)
 		osession_type = options.session_type;
 		orequest_tty = options.request_tty;
 		otty_flag = tty_flag;
+		ofork_after_authentication = options.fork_after_authentication;
 		options.stdin_null = 1;
 		options.session_type = SESSION_TYPE_NONE;
 		tty_flag = 0;
-		if (!options.fork_after_authentication &&
-		    (osession_type != SESSION_TYPE_NONE ||
+		if ((osession_type != SESSION_TYPE_NONE ||
 		    options.stdio_forward_host != NULL))
 			need_controlpersist_detach = 1;
 		options.fork_after_authentication = 1;