upstream: close stdout/stderr after "ssh -f ..." forking

bz#3137, ok markus

OpenBSD-Commit-ID: e2d83cc4dea1665651a7aa924ad1ed6bcaaab3e2

diff --git a/ssh.c b/ssh.c
index 9c6a6278bb4a4f52e5d44969c216f48dce1b3db7..6202e3c097f6bf5798e6a6aff832f7a81b4e8441 100644 (file)
--- a/ssh.c
+++ b/ssh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.534 2020/07/31 04:19:37 dtucker Exp $ */
+/* $OpenBSD: ssh.c,v 1.535 2020/09/20 23:31:46 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -1745,12 +1745,25 @@ control_persist_detach(void)
 static void
 fork_postauth(void)
 {
+       int devnull, keep_stderr;
+
        if (need_controlpersist_detach)
                control_persist_detach();
        debug("forking to background");
        fork_after_authentication_flag = 0;
        if (daemon(1, 1) == -1)
                fatal("daemon() failed: %.200s", strerror(errno));
+       if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1)
+               error("%s: open %s: %s", __func__,
+                   _PATH_DEVNULL, strerror(errno));
+       else {
+               keep_stderr = log_is_on_stderr() && debug_flag;
+               if (dup2(devnull, STDOUT_FILENO) == -1 ||
+                   (!keep_stderr && dup2(devnull, STDOUT_FILENO) == -1))
+                       fatal("%s: dup2() stdio failed", __func__);
+               if (devnull > STDERR_FILENO)
+                       close(devnull);
+       }
 }
 
 static void
@@ -2149,13 +2162,15 @@ ssh_session2(struct ssh *ssh, struct passwd *pw)
         * as it may want to write to stdout.
         */
        if (!need_controlpersist_detach) {
-               if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1)
+               if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1) {
                        error("%s: open %s: %s", __func__,
                            _PATH_DEVNULL, strerror(errno));
-               if (dup2(devnull, STDOUT_FILENO) == -1)
-                       fatal("%s: dup2() stdout failed", __func__);
-               if (devnull > STDERR_FILENO)
-                       close(devnull);
+               } else {
+                       if (dup2(devnull, STDOUT_FILENO) == -1)
+                               fatal("%s: dup2() stdout failed", __func__);
+                       if (devnull > STDERR_FILENO)
+                               close(devnull);
+               }
        }
 
        /*