- djm@cvs.openbsd.org 2007/09/04 03:21:03

[clientloop.c monitor.c monitor_fdpass.c monitor_fdpass.h]
     [monitor_wrap.c ssh.c]
     make file descriptor passing code return an error rather than call fatal()
     when it encounters problems, and use this to make session multiplexing
     masters survive slaves failing to pass all stdio FDs; ok markus@

ChangeLog

@@ -19,6 +19,12 @@
    - djm@cvs.openbsd.org 2007/08/23 03:23:26
      [sshconnect.c]
      Execute ProxyCommands with $SHELL rather than /bin/sh unconditionally
+   - djm@cvs.openbsd.org 2007/09/04 03:21:03
+     [clientloop.c monitor.c monitor_fdpass.c monitor_fdpass.h]
+     [monitor_wrap.c ssh.c]
+     make file descriptor passing code return an error rather than call fatal()
+     when it encounters problems, and use this to make session multiplexing
+     masters survive slaves failing to pass all stdio FDs; ok markus@
 
 20070914
  - (dtucker) [openbsd-compat/bsd-asprintf.c] Plug mem leak in error path.
@@ -3216,4 +3222,4 @@
    OpenServer 6 and add osr5bigcrypt support so when someone migrates
    passwords between UnixWare and OpenServer they will still work. OK dtucker@
 
-$Id: ChangeLog,v 1.4747 2007/09/17 01:58:04 djm Exp $
+$Id: ChangeLog,v 1.4748 2007/09/17 02:04:08 djm Exp $

clientloop.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.c,v 1.181 2007/08/15 08:14:46 markus Exp $ */
+/* $OpenBSD: clientloop.c,v 1.182 2007/09/04 03:21:03 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -722,7 +722,7 @@ client_process_control(fd_set *readset)
 	struct sockaddr_storage addr;
 	struct confirm_ctx *cctx;
 	char *cmd;
-	u_int i, len, env_len, command, flags;
+	u_int i, j, len, env_len, command, flags;
 	uid_t euid;
 	gid_t egid;
 
@@ -870,9 +870,22 @@ client_process_control(fd_set *readset)
 	xfree(cmd);
 
 	/* Gather fds from client */
-	new_fd[0] = mm_receive_fd(client_fd);
+	for(i = 0; i < 3; i++) {
-	new_fd[1] = mm_receive_fd(client_fd);
+		if ((new_fd[i] = mm_receive_fd(client_fd)) == -1) {
-	new_fd[2] = mm_receive_fd(client_fd);
+			error("%s: failed to receive fd %d from slave",
+			    __func__, i);
+			for (j = 0; j < i; j++)
+				close(new_fd[j]);
+			for (j = 0; j < env_len; j++)
+				xfree(cctx->env[j]);
+			if (env_len > 0)
+				xfree(cctx->env);
+			xfree(cctx->term);
+			buffer_free(&cctx->cmd);
+			xfree(cctx);
+			return;
+		}
+	}
 
 	debug2("%s: got fds stdin %d, stdout %d, stderr %d", __func__,
 	    new_fd[0], new_fd[1], new_fd[2]);

monitor.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor.c,v 1.91 2007/05/17 20:52:13 djm Exp $ */
+/* $OpenBSD: monitor.c,v 1.92 2007/09/04 03:21:03 djm Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -1314,8 +1314,9 @@ mm_answer_pty(int sock, Buffer *m)
 
 	mm_request_send(sock, MONITOR_ANS_PTY, m);
 
-	mm_send_fd(sock, s->ptyfd);
+	if (mm_send_fd(sock, s->ptyfd) == -1 ||
-	mm_send_fd(sock, s->ttyfd);
+	    mm_send_fd(sock, s->ttyfd) == -1)
+		fatal("%s: send fds failed", __func__);
 
 	/* make sure nothing uses fd 0 */
 	if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) < 0)

monitor_fdpass.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor_fdpass.c,v 1.12 2006/08/03 03:34:42 deraadt Exp $ */
+/* $OpenBSD: monitor_fdpass.c,v 1.13 2007/09/04 03:21:03 djm Exp $ */
 /*
  * Copyright 2001 Niels Provos <provos@citi.umich.edu>
  * All rights reserved.
@@ -40,7 +40,7 @@
 #include "log.h"
 #include "monitor_fdpass.h"
 
-void
+int
 mm_send_fd(int sock, int fd)
 {
 #if defined(HAVE_SENDMSG) && (defined(HAVE_ACCRIGHTS_IN_MSGHDR) || defined(HAVE_CONTROL_IN_MSGHDR))
@@ -72,15 +72,21 @@ mm_send_fd(int sock, int fd)
 	msg.msg_iov = &vec;
 	msg.msg_iovlen = 1;
 
-	if ((n = sendmsg(sock, &msg, 0)) == -1)
+	if ((n = sendmsg(sock, &msg, 0)) == -1) {
-		fatal("%s: sendmsg(%d): %s", __func__, fd,
+		error("%s: sendmsg(%d): %s", __func__, fd,
 		    strerror(errno));
-	if (n != 1)
+		return -1;
-		fatal("%s: sendmsg: expected sent 1 got %ld",
+	}
+
+	if (n != 1) {
+		error("%s: sendmsg: expected sent 1 got %ld",
 		    __func__, (long)n);
+		return -1;
+	}
+	return 0;
 #else
-	fatal("%s: UsePrivilegeSeparation=yes not supported",
+	error("%s: file descriptor passing not supported", __func__);
-	    __func__);
+	return -1;
 #endif
 }
 
@@ -111,29 +117,39 @@ mm_receive_fd(int sock)
 	msg.msg_controllen = sizeof(tmp);
 #endif
 
-	if ((n = recvmsg(sock, &msg, 0)) == -1)
+	if ((n = recvmsg(sock, &msg, 0)) == -1) {
-		fatal("%s: recvmsg: %s", __func__, strerror(errno));
+		error("%s: recvmsg: %s", __func__, strerror(errno));
-	if (n != 1)
+		return -1;
-		fatal("%s: recvmsg: expected received 1 got %ld",
+	}
+	if (n != 1) {
+		error("%s: recvmsg: expected received 1 got %ld",
 		    __func__, (long)n);
+		return -1;
+	}
 
 #ifdef HAVE_ACCRIGHTS_IN_MSGHDR
-	if (msg.msg_accrightslen != sizeof(fd))
+	if (msg.msg_accrightslen != sizeof(fd)) {
-		fatal("%s: no fd", __func__);
+		error("%s: no fd", __func__);
+		return -1;
+	}
 #else
 	cmsg = CMSG_FIRSTHDR(&msg);
-	if (cmsg == NULL)
+	if (cmsg == NULL) {
-		fatal("%s: no message header", __func__);
+		error("%s: no message header", __func__);
+		return -1;
+	}
 #ifndef BROKEN_CMSG_TYPE
-	if (cmsg->cmsg_type != SCM_RIGHTS)
+	if (cmsg->cmsg_type != SCM_RIGHTS) {
-		fatal("%s: expected type %d got %d", __func__,
+		error("%s: expected type %d got %d", __func__,
 		    SCM_RIGHTS, cmsg->cmsg_type);
+		return -1;
+	}
 #endif
 	fd = (*(int *)CMSG_DATA(cmsg));
 #endif
 	return fd;
 #else
-	fatal("%s: UsePrivilegeSeparation=yes not supported",
+	error("%s: file descriptor passing not supported", __func__);
-	    __func__);
+	return -1;
 #endif
 }

monitor_fdpass.h

@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor_fdpass.h,v 1.3 2006/03/25 22:22:43 djm Exp $ */
+/* $OpenBSD: monitor_fdpass.h,v 1.4 2007/09/04 03:21:03 djm Exp $ */
 
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
@@ -28,7 +28,7 @@
 #ifndef _MM_FDPASS_H_
 #define _MM_FDPASS_H_
 
-void mm_send_fd(int, int);
+int mm_send_fd(int, int);
 int mm_receive_fd(int);
 
 #endif /* _MM_FDPASS_H_ */

monitor_wrap.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor_wrap.c,v 1.57 2007/06/07 19:37:34 pvalchev Exp $ */
+/* $OpenBSD: monitor_wrap.c,v 1.58 2007/09/04 03:21:03 djm Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -688,8 +688,9 @@ mm_pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, size_t namebuflen)
 	buffer_append(&loginmsg, msg, strlen(msg));
 	xfree(msg);
 
-	*ptyfd = mm_receive_fd(pmonitor->m_recvfd);
+	if ((*ptyfd = mm_receive_fd(pmonitor->m_recvfd)) == -1 ||
-	*ttyfd = mm_receive_fd(pmonitor->m_recvfd);
+	    (*ttyfd = mm_receive_fd(pmonitor->m_recvfd)) == -1)
+		fatal("%s: receive fds failed", __func__);
 
 	/* Success */
 	return (1);

ssh.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.301 2007/08/07 07:32:53 djm Exp $ */
+/* $OpenBSD: ssh.c,v 1.302 2007/09/04 03:21:03 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -1426,9 +1426,10 @@ control_client(const char *path)
 	if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
 		fatal("%s: msg_send", __func__);
 
-	mm_send_fd(sock, STDIN_FILENO);
+	if (mm_send_fd(sock, STDIN_FILENO) == -1 ||
-	mm_send_fd(sock, STDOUT_FILENO);
+	    mm_send_fd(sock, STDOUT_FILENO) == -1 ||
-	mm_send_fd(sock, STDERR_FILENO);
+	    mm_send_fd(sock, STDERR_FILENO) == -1)
+		fatal("%s: send fds failed", __func__);
 
 	/* Wait for reply, so master has a chance to gather ttymodes */
 	buffer_clear(&m);