[openssh-commits] [openssh] 05/06: upstream: backout
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djm pushed a commit to branch master
in repository openssh.
commit fc6ca48d15419f23a6a2ea3c0115b8f32c3dcc69
Author: djm at openbsd.org <djm at openbsd.org>
AuthorDate: Wed Sep 23 21:42:39 2026 +0000
upstream: backout
> avoid race between multiple processes attempting to
>
> establish multiplexing control socket by moving socket creation earlier in
> ssh(1)'s life. Patch from Jens Rosenboom via bz3971
It caused problems with ControlPersist sessions.
Reported by semarie@ job@
OpenBSD-Commit-ID: b78a34d605c47cb145e16a3bba295caa0e9db680
---
clientloop.h | 3 +--
mux.c | 73 ++++++++++++++++++++++++++++++------------------------------
ssh.c | 8 ++-----
3 files changed, 39 insertions(+), 45 deletions(-)
diff --git a/clientloop.h b/clientloop.h
index 7509de26b..51c8cfb35 100644
--- a/clientloop.h
+++ b/clientloop.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.h,v 1.42 2026/09/22 03:22:00 djm Exp $ */
+/* $OpenBSD: clientloop.h,v 1.43 2026/09/23 21:42:39 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo at cs.hut.fi>
@@ -78,7 +78,6 @@ void client_expect_confirm(struct ssh *, int, const char *,
#define SSHMUX_COMMAND_CONNINFO 9 /* Show connection information */
#define SSHMUX_COMMAND_CHANINFO 10 /* Show channels information */
-int muxserver(const char *);
void muxserver_listen(struct ssh *);
int muxclient(const char *);
void mux_exit_message(struct ssh *, Channel *, int);
diff --git a/mux.c b/mux.c
index 005e8375b..e77493823 100644
--- a/mux.c
+++ b/mux.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: mux.c,v 1.115 2026/09/22 03:22:00 djm Exp $ */
+/* $OpenBSD: mux.c,v 1.116 2026/09/23 21:42:39 djm Exp $ */
/*
* Copyright (c) 2002-2008 Damien Miller <djm at openbsd.org>
*
@@ -1315,20 +1315,21 @@ mux_tty_alloc_failed(struct ssh *ssh, Channel *c)
sshbuf_free(m);
}
-/*
- * Create a listening Unix domain socket for mux master or find out that
- * one exists already.
- */
-int
-muxserver(const char *path)
+/* Prepare a mux master to listen on a Unix domain socket. */
+void
+muxserver_listen(struct ssh *ssh)
{
mode_t old_umask;
- char *tmp_path;
+ char *orig_control_path = options.control_path;
char rbuf[16+1];
u_int i, r;
int oerrno;
- debug("trying to setup multiplex master socket at %s", path);
+ if (options.control_path == NULL ||
+ options.control_master == SSHCTL_MASTER_NO)
+ return;
+
+ debug("setting up multiplex master socket");
/*
* Use a temporary path before listen so we can pseudo-atomically
@@ -1343,53 +1344,51 @@ muxserver(const char *path)
'0' + r - 26 - 26;
}
rbuf[sizeof(rbuf) - 1] = '\0';
- xasprintf(&tmp_path, "%s.%s", path, rbuf);
- debug3_f("temporary control path %s", tmp_path);
+ options.control_path = NULL;
+ xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf);
+ debug3_f("temporary control path %s", options.control_path);
old_umask = umask(0177);
- muxserver_sock = unix_listener(tmp_path, 64, 0);
+ muxserver_sock = unix_listener(options.control_path, 64, 0);
oerrno = errno;
umask(old_umask);
if (muxserver_sock < 0) {
if (oerrno == EINVAL || oerrno == EADDRINUSE) {
- error("Temporary ControlSocket %s already exists", tmp_path);
- free(tmp_path);
- return -1;
+ error("ControlSocket %s already exists, "
+ "disabling multiplexing", options.control_path);
+ disable_mux_master:
+ if (muxserver_sock != -1) {
+ close(muxserver_sock);
+ muxserver_sock = -1;
+ }
+ free(orig_control_path);
+ free(options.control_path);
+ options.control_path = NULL;
+ options.control_master = SSHCTL_MASTER_NO;
+ return;
} else {
/* unix_listener() logs the error */
cleanup_exit(255);
}
}
- set_nonblock(muxserver_sock);
/* Now atomically "move" the mux socket into position */
- if (link(tmp_path, path) != 0) {
+ if (link(options.control_path, orig_control_path) != 0) {
if (errno != EEXIST) {
fatal_f("link mux listener %s => %s: %s",
- tmp_path, path,
+ options.control_path, orig_control_path,
strerror(errno));
}
- debug("ControlSocket %s already exists", path);
- close(muxserver_sock);
- muxserver_sock = -1;
+ error("ControlSocket %s already exists, disabling multiplexing",
+ orig_control_path);
+ unlink(options.control_path);
+ goto disable_mux_master;
}
- unlink(tmp_path);
- free(tmp_path);
- return muxserver_sock;
-}
+ unlink(options.control_path);
+ free(options.control_path);
+ options.control_path = orig_control_path;
-/* Prepare a mux master to listen on the previously created Unix domain socket. */
-void
-muxserver_listen(struct ssh *ssh)
-{
- if (options.control_path == NULL ||
- options.control_master == SSHCTL_MASTER_NO)
- return;
-
- debug("setting up multiplex master socket");
- if (muxserver_sock < 0) {
- muxserver_sock = muxserver(options.control_path);
- }
+ set_nonblock(muxserver_sock);
mux_listener_channel = channel_new(ssh, "mux listener",
SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1,
diff --git a/ssh.c b/ssh.c
index 0640abe49..fe660efbd 100644
--- a/ssh.c
+++ b/ssh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.641 2026/09/22 03:22:00 djm Exp $ */
+/* $OpenBSD: ssh.c,v 1.642 2026/09/23 21:42:39 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo at cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo at cs.hut.fi>, Espoo, Finland
@@ -1634,11 +1634,7 @@ main(int ac, char **av)
fatal("No ControlPath specified for \"-O\" command");
if (options.control_path != NULL) {
int sock;
-
- if (muxclient_command == 0 &&
- (sock = muxserver(options.control_path)) >= 0) {
- debug("We will be multiplex master, not client.");
- } else if ((sock = muxclient(options.control_path)) >= 0) {
+ if ((sock = muxclient(options.control_path)) >= 0) {
if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
fatal("ssh_packet_set_connection failed");
ssh_packet_set_mux(ssh);
--
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