[openssh-commits] [openssh] 02/07: upstream commit

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djm pushed a commit to branch master
in repository openssh.

commit 7fc4766ac78abae81ee75b22b7550720bfa28a33
Author: dtucker at openbsd.org <dtucker at openbsd.org>
Date:   Wed Nov 30 00:28:31 2016 +0000

    upstream commit
    
    On startup, check to see if sshd is already daemonized
    and if so, skip the call to daemon() and do not rewrite the PidFile.  This
    means that when sshd re-execs itself on SIGHUP the process ID will no longer
    change.  Should address bz#2641.  ok djm@ markus at .
    
    Upstream-ID: 5ea0355580056fb3b25c1fd6364307d9638a37b9
---
 misc.c | 20 +++++++++++++++++++-
 misc.h |  3 ++-
 sshd.c | 15 ++++++++-------
 3 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/misc.c b/misc.c
index 07d4179..65c9222 100644
--- a/misc.c
+++ b/misc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: misc.c,v 1.106 2016/10/23 22:04:05 dtucker Exp $ */
+/* $OpenBSD: misc.c,v 1.107 2016/11/30 00:28:31 dtucker Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2005,2006 Damien Miller.  All rights reserved.
@@ -1251,3 +1251,21 @@ bind_permitted(int port, uid_t uid)
 		return 0;
 	return 1;
 }
+
+/* returns 1 if process is already daemonized, 0 otherwise */
+int
+daemonized(void)
+{
+	int fd;
+
+	if ((fd = open(_PATH_TTY, O_RDONLY | O_NOCTTY)) >= 0) {
+		close(fd);
+		return 0;	/* have controlling terminal */
+	}
+	if (getppid() != 1)
+		return 0;	/* parent is not init */
+	if (getsid(0) != getpid())
+		return 0;	/* not session leader */
+	debug3("already daemonized");
+	return 1;
+}
diff --git a/misc.h b/misc.h
index 3578e8e..c242f90 100644
--- a/misc.h
+++ b/misc.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: misc.h,v 1.60 2016/10/23 22:04:05 dtucker Exp $ */
+/* $OpenBSD: misc.h,v 1.61 2016/11/30 00:28:31 dtucker Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo at cs.hut.fi>
@@ -31,6 +31,7 @@ struct Forward {
 
 int forward_equals(const struct Forward *, const struct Forward *);
 int bind_permitted(int, uid_t);
+int daemonized(void);
 
 /* Common server and client forwarding options. */
 struct ForwardOptions {
diff --git a/sshd.c b/sshd.c
index ce4a493..fafcd34 100644
--- a/sshd.c
+++ b/sshd.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshd.c,v 1.477 2016/11/29 03:54:50 dtucker Exp $ */
+/* $OpenBSD: sshd.c,v 1.478 2016/11/30 00:28:31 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo at cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo at cs.hut.fi>, Espoo, Finland
@@ -1343,7 +1343,7 @@ main(int ac, char **av)
 	struct ssh *ssh = NULL;
 	extern char *optarg;
 	extern int optind;
-	int r, opt, i, j, on = 1;
+	int r, opt, i, j, on = 1, already_daemon;
 	int sock_in = -1, sock_out = -1, newsock = -1;
 	const char *remote_ip;
 	int remote_port;
@@ -1802,11 +1802,12 @@ main(int ac, char **av)
 	log_init(__progname, options.log_level, options.log_facility, log_stderr);
 
 	/*
-	 * If not in debugging mode, and not started from inetd, disconnect
-	 * from the controlling terminal, and fork.  The original process
-	 * exits.
+	 * If not in debugging mode, not started from inetd and not already
+	 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling
+	 * terminal, and fork.  The original process exits.
 	 */
-	if (!(debug_flag || inetd_flag || no_daemon_flag)) {
+	already_daemon = daemonized();
+	if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) {
 
 		if (daemon(0, 0) < 0)
 			fatal("daemon() failed: %.200s", strerror(errno));
@@ -1840,7 +1841,7 @@ main(int ac, char **av)
 		 * Write out the pid file after the sigterm handler
 		 * is setup and the listen sockets are bound
 		 */
-		if (options.pid_file != NULL && !debug_flag) {
+		if (options.pid_file != NULL && !debug_flag && !already_daemon) {
 			FILE *f = fopen(options.pid_file, "w");
 
 			if (f == NULL) {

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