tls: prepare for ECDH_anon ciphers

[oweals/busybox.git] / loginutils / sulogin.c

diff --git a/loginutils/sulogin.c b/loginutils/sulogin.c
index 8cfb64e9ac1c93dd9e49fe0b53d8e060dd26f302..27ea5dff028b62a18b7adb46b8c04dff34f359b0 100644 (file)
--- a/loginutils/sulogin.c
+++ b/loginutils/sulogin.c
@@ -2,112 +2,92 @@
 /*
  * Mini sulogin implementation for busybox
  *
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
+//config:config SULOGIN
+//config:      bool "sulogin (17 kb)"
+//config:      default y
+//config:      select FEATURE_SYSLOG
+//config:      help
+//config:      sulogin is invoked when the system goes into single user
+//config:      mode (this is done through an entry in inittab).
 
-#include <syslog.h>
+//applet:IF_SULOGIN(APPLET_NOEXEC(sulogin, sulogin, BB_DIR_SBIN, BB_SUID_DROP, sulogin))
 
-#include "busybox.h"
-
-static const char * const forbid[] = {
-       "ENV",
-       "BASH_ENV",
-       "HOME",
-       "IFS",
-       "PATH",
-       "SHELL",
-       "LD_LIBRARY_PATH",
-       "LD_PRELOAD",
-       "LD_TRACE_LOADED_OBJECTS",
-       "LD_BIND_NOW",
-       "LD_AOUT_LIBRARY_PATH",
-       "LD_AOUT_PRELOAD",
-       "LD_NOWARN",
-       "LD_KEEPDIR",
-       (char *) 0
-};
-
-
-static void catchalarm(int ATTRIBUTE_UNUSED junk)
-{
-       exit(EXIT_FAILURE);
-}
+//kbuild:lib-$(CONFIG_SULOGIN) += sulogin.o
+
+//usage:#define sulogin_trivial_usage
+//usage:       "[-t N] [TTY]"
+//usage:#define sulogin_full_usage "\n\n"
+//usage:       "Single user login\n"
+//usage:     "\n       -t N    Timeout"
 
+#include "libbb.h"
+#include <syslog.h>
 
-int sulogin_main(int argc, char **argv)
+int sulogin_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int sulogin_main(int argc UNUSED_PARAM, char **argv)
 {
-       char *cp;
        int timeout = 0;
-       char *timeout_arg;
-       const char * const *p;
        struct passwd *pwd;
-       struct spwd *spwd;
+       const char *shell;
+
+       /* Note: sulogin is not a suid app. It is meant to be run by init
+        * for single user / emergency mode. init starts it as root.
+        * Normal users (potentially malicious ones) can only run it under
+        * their UID, therefore no paranoia here is warranted:
+        * $LD_LIBRARY_PATH in env, TTY = /dev/sda
+        * are no more dangerous here than in e.g. cp applet.
+        */
 
        logmode = LOGMODE_BOTH;
-       openlog(bb_applet_name, 0, LOG_AUTH);
+       openlog(applet_name, 0, LOG_AUTH);
 
-       if (bb_getopt_ulflags (argc, argv, "t:", &timeout_arg)) {
-               if (safe_strtoi(timeout_arg, &timeout)) {
-                       timeout = 0;
-               }
-       }
+       getopt32(argv, "t:+", &timeout);
+       argv += optind;
 
-       if (argv[optind]) {
+       if (argv[0]) {
                close(0);
                close(1);
-               dup(xopen(argv[optind], O_RDWR));
+               dup(xopen(argv[0], O_RDWR));
                close(2);
                dup(0);
        }
 
-       if (!isatty(0) || !isatty(1) || !isatty(2)) {
-               logmode = LOGMODE_SYSLOG;
-               bb_error_msg_and_die("not a tty");
-       }
-
-       /* Clear out anything dangerous from the environment */
-       for (p = forbid; *p; p++)
-               unsetenv(*p);
-
-       signal(SIGALRM, catchalarm);
-
-       if (!(pwd = getpwuid(0))) {
-               goto auth_error;
-       }
-
-       if (ENABLE_FEATURE_SHADOWPASSWDS) {
-               if (!(spwd = getspnam(pwd->pw_name))) {
-                       goto auth_error;
-               }
-               pwd->pw_passwd = spwd->sp_pwdp;
+       pwd = getpwuid(0);
+       if (!pwd) {
+               bb_error_msg_and_die("no password entry for root");
        }
 
        while (1) {
-               /* cp points to a static buffer that is zeroed every time */
-               cp = bb_askpass(timeout,
-                               "Give root password for system maintenance\n"
-                               "(or type Control-D for normal startup):");
-
-               if (!cp || !*cp) {
-                       bb_info_msg("Normal startup");
+               int r;
+
+               r = ask_and_check_password_extended(pwd, timeout,
+                       "Give root password for system maintenance\n"
+                       "(or type Control-D for normal startup):"
+               );
+               if (r < 0) {
+                       /* ^D, ^C, timeout, or read error */
+                       bb_error_msg("normal startup");
                        return 0;
                }
-               if (strcmp(pw_encrypt(cp, pwd->pw_passwd), pwd->pw_passwd) == 0) {
+               if (r > 0) {
                        break;
                }
-               bb_do_delay(FAIL_DELAY);
-               bb_error_msg("login incorrect");
+               bb_do_delay(LOGIN_FAIL_DELAY);
+               bb_error_msg("Login incorrect");
        }
-       memset(cp, 0, strlen(cp));
-       signal(SIGALRM, SIG_DFL);
 
-       bb_info_msg("System Maintenance Mode");
+       bb_error_msg("starting shell for system maintenance");
 
-       USE_SELINUX(renew_current_security_context());
+       IF_SELINUX(renew_current_security_context());
 
-       run_shell(pwd->pw_shell, 1, 0, 0);
-       /* never returns */
+       shell = getenv("SUSHELL");
+       if (!shell)
+               shell = getenv("sushell");
+       if (!shell)
+               shell = pwd->pw_shell;
 
-auth_error:
-       bb_error_msg_and_die("no password entry for `root'");
+       /* Exec login shell with no additional parameters. Never returns. */
+       run_shell(shell, 1, NULL);
 }