- djm@cvs.openbsd.org 2010/08/12 21:49:44
[ssh.c]
close any extra file descriptors inherited from parent at start and
reopen stdin/stdout to /dev/null when forking for ControlPersist.
prevents tools that fork and run a captive ssh for communication from
failing to exit when the ssh completes while they wait for these fds to
close. The inherited fds may persist arbitrarily long if a background
mux master has been started by ControlPersist. cvs and scp were effected
by this.
"please commit" markus@
diff --git a/ssh.c b/ssh.c
index ab37c20..4419f76 100644
--- a/ssh.c
+++ b/ssh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.345 2010/08/04 05:42:47 djm Exp $ */
+/* $OpenBSD: ssh.c,v 1.346 2010/08/12 21:49:44 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -238,6 +238,12 @@
init_rng();
/*
+ * Discard other fds that are hanging around. These can cause problem
+ * with backgrounded ssh processes started by ControlPersist.
+ */
+ closefrom(STDERR_FILENO + 1);
+
+ /*
* Save the original real uid. It will be needed later (uid-swapping
* may clobber the real uid).
*/
@@ -898,6 +904,7 @@
control_persist_detach(void)
{
pid_t pid;
+ int devnull;
debug("%s: backgrounding master process", __func__);
@@ -924,6 +931,16 @@
/* muxclient() doesn't return on success. */
fatal("Failed to connect to new control master");
}
+ if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
+ error("%s: open(\"/dev/null\"): %s", __func__,
+ strerror(errno));
+ } else {
+ if (dup2(devnull, STDIN_FILENO) == -1 ||
+ dup2(devnull, STDOUT_FILENO) == -1)
+ error("%s: dup2: %s", __func__, strerror(errno));
+ if (devnull > STDERR_FILENO)
+ close(devnull);
+ }
}
/* Do fork() after authentication. Used by "ssh -f" */