From 9cc9e3ddbb9c49b34bffe31fdbc8a3505145d508 Mon Sep 17 00:00:00 2001
From: Joachim Wiberg <troglobit@gmail.com>
Date: Sun, 30 May 2021 12:42:48 +0200
Subject: [PATCH] getty: if we cannot execute /bin/login, try sulogin before
 /bin/sh

Basic security measure, don't bail to shell if we cannot find/exec
login, instead try sulogin before falling back to plain shell.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
---
 src/Makefile.am |  2 +-
 src/finit.h     |  1 +
 src/getty.c     | 15 ++++++++++-----
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/Makefile.am b/src/Makefile.am
index bee9ae62..27200f87 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -19,7 +19,7 @@ endif
 finit_pkglibdir      = $(pkglibdir)
 finit_pkglib_SCRIPTS = rescue.conf sample.conf
 
-getty_SOURCES        = getty.c helpers.h logrotate.c stty.c utmp-api.c utmp-api.h
+getty_SOURCES        = finit.h getty.c helpers.h logrotate.c stty.c utmp-api.c utmp-api.h
 getty_CFLAGS         = -W -Wall -Wextra -std=gnu99
 getty_CFLAGS        += $(lite_CFLAGS)
 getty_LDADD          = $(lite_LIBS)
diff --git a/src/finit.h b/src/finit.h
index 86574dba..8c13aba5 100644
--- a/src/finit.h
+++ b/src/finit.h
@@ -50,6 +50,7 @@
 #define FINIT_CGPATH            "/sys/fs/cgroup"
 #endif
 
+/* To use these, include config.h, or define FINIT_LIBPATH_ */
 #define _PATH_LOGIT             FINIT_LIBPATH_ "/logit"
 #define _PATH_SULOGIN           FINIT_LIBPATH_ "/sulogin"
 #define _PATH_GETTY             FINIT_LIBPATH_ "/getty"
diff --git a/src/getty.c b/src/getty.c
index e7c43a3c..4a88f5e2 100644
--- a/src/getty.c
+++ b/src/getty.c
@@ -21,6 +21,8 @@
  * THE SOFTWARE.
  */
 
+#include "config.h"
+
 #include <err.h>
 #include <errno.h>
 #include <paths.h>
@@ -32,6 +34,7 @@
 #include <sys/ttydefaults.h>	/* Not included by default in musl libc */
 #include <termios.h>
 
+#include "finit.h"
 #include "helpers.h"
 #include "utmp-api.h"
 
@@ -179,12 +182,14 @@ static int do_login(char *name)
 	/*
 	 * Failed to exec login, should not happen on normal systems.
 	 * Try a starting a rescue shell instead.
-	 *
-	 * Note: Add /etc/securetty handling.
 	 */
-	warnx("Failed exec %s, attempting fallback to %s ...", _PATH_LOGIN, _PATH_BSHELL);
-	if (fstat(0, &st) == 0 && S_ISCHR(st.st_mode))
-		execl(_PATH_BSHELL, _PATH_BSHELL, NULL); /* XXX: run sulogin instead! */
+	if (fstat(0, &st) == 0 && S_ISCHR(st.st_mode)) {
+		warnx("Failed exec %s, attempting fallback to %s ...", _PATH_LOGIN, _PATH_SULOGIN);
+		execl(_PATH_SULOGIN, _PATH_SULOGIN, NULL);
+
+		warnx("Failed exec %s, attempting fallback to %s ...", _PATH_SULOGIN, _PATH_BSHELL);
+		execl(_PATH_BSHELL, _PATH_BSHELL, NULL);
+	}
 
 	return 1;	/* We shouldn't get here ... */
 }