[openssh-commits] [openssh] 08/10: upstream: wait for the unprivileged sshd-auth process to exit

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djm pushed a commit to branch master
in repository openssh.

commit a071af0682d686de85cf471f5e04deaee4d90adb
Author: djm at openbsd.org <djm at openbsd.org>
AuthorDate: Thu Sep 25 06:45:50 2025 +0000

    upstream: wait for the unprivileged sshd-auth process to exit
    
    before closing the fd it uses to report log messages
    
    This avoids a race where the child process notices the
    fd was closed before exiting and spams the logs.
    
    ok dtucker@
    
    OpenBSD-Commit-ID: 7cddaa41be3b955e6bed570900db7ab8817b1e76
---
 monitor.c      | 22 ++++++++++++++++++++--
 sshd-session.c | 20 ++------------------
 2 files changed, 22 insertions(+), 20 deletions(-)

diff --git a/monitor.c b/monitor.c
index 563a0f0cb..a9e854bec 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor.c,v 1.248 2025/09/15 04:47:49 djm Exp $ */
+/* $OpenBSD: monitor.c,v 1.249 2025/09/25 06:45:50 djm Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos at citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus at openbsd.org>
@@ -262,7 +262,7 @@ void
 monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor)
 {
 	struct mon_table *ent;
-	int authenticated = 0, partial = 0;
+	int status, authenticated = 0, partial = 0;
 
 	debug3("preauth child monitor started");
 
@@ -365,11 +365,29 @@ monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor)
 	while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0)
 		;
 
+	/* Wait for the child's exit status */
+	while (waitpid(pmonitor->m_pid, &status, 0) == -1) {
+		if (errno == EINTR)
+			continue;
+		fatal_f("waitpid: %s", strerror(errno));
+	}
+	if (WIFEXITED(status)) {
+		if (WEXITSTATUS(status) != 0)
+			fatal_f("preauth child %ld exited with status %d",
+			    (long)pmonitor->m_pid, WEXITSTATUS(status));
+	} else if (WIFSIGNALED(status)) {
+		fatal_f("preauth child %ld terminated by signal %d",
+		    (long)pmonitor->m_pid, WTERMSIG(status));
+	}
+	debug3_f("preauth child %ld terminated successfully",
+	    (long)pmonitor->m_pid);
+
 	if (pmonitor->m_recvfd >= 0)
 		close(pmonitor->m_recvfd);
 	if (pmonitor->m_log_sendfd >= 0)
 		close(pmonitor->m_log_sendfd);
 	pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1;
+	pmonitor->m_pid = -1;
 }
 
 static void
diff --git a/sshd-session.c b/sshd-session.c
index 7abc2b4a5..8979f743b 100644
--- a/sshd-session.c
+++ b/sshd-session.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshd-session.c,v 1.15 2025/08/29 03:50:38 djm Exp $ */
+/* $OpenBSD: sshd-session.c,v 1.16 2025/09/25 06:45:50 djm Exp $ */
 /*
  * SSH2 implementation:
  * Privilege Separation:
@@ -330,7 +330,7 @@ pack_hostkeys(void)
 static int
 privsep_preauth(struct ssh *ssh)
 {
-	int status, r;
+	int r;
 	pid_t pid;
 
 	/* Set up unprivileged child process to deal with network data */
@@ -352,23 +352,7 @@ privsep_preauth(struct ssh *ssh)
 			}
 		}
 		monitor_child_preauth(ssh, pmonitor);
-
-		/* Wait for the child's exit status */
-		while (waitpid(pid, &status, 0) == -1) {
-			if (errno == EINTR)
-				continue;
-			pmonitor->m_pid = -1;
-			fatal_f("waitpid: %s", strerror(errno));
-		}
 		privsep_is_preauth = 0;
-		pmonitor->m_pid = -1;
-		if (WIFEXITED(status)) {
-			if (WEXITSTATUS(status) != 0)
-				fatal_f("preauth child exited with status %d",
-				    WEXITSTATUS(status));
-		} else if (WIFSIGNALED(status))
-			fatal_f("preauth child terminated by signal %d",
-			    WTERMSIG(status));
 		return 1;
 	} else {
 		/* child */

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