Changeset 3621 in MondoRescue for branches/3.3/mindi-busybox/loginutils/sulogin.c

Timestamp:

Dec 20, 2016, 4:07:32 PM (7 years ago)

Author:

Bruno Cornec

Message:

New 3?3 banch for incorporation of latest busybox 1.25. Changing minor version to handle potential incompatibilities.

Location:

branches/3.3

Files:

• . (copied) (copied from branches/3.2 )
• mindi-busybox/loginutils/sulogin.c (modified) (4 diffs)

branches/3.3/mindi-busybox/loginutils/sulogin.c

@@ -5 +5 @@
  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
+//config:config SULOGIN
+//config:   bool "sulogin"
+//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).
+
+//applet:IF_SULOGIN(APPLET(sulogin, BB_DIR_SBIN, BB_SUID_DROP))
+
+//kbuild:lib-$(CONFIG_SULOGIN) += sulogin.o
 
 //usage:#define sulogin_trivial_usage
@@ -15 +26 @@
 #include <syslog.h>
 
-//static void catchalarm(int UNUSED_PARAM junk)
-//{
-//  exit(EXIT_FAILURE);
-//}
-
-
 int sulogin_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int sulogin_main(int argc UNUSED_PARAM, char **argv)
 {
-    char *cp;
     int timeout = 0;
     struct passwd *pwd;
     const char *shell;
-#if ENABLE_FEATURE_SHADOWPASSWDS
-    /* Using _r function to avoid pulling in static buffers */
-    char buffer[256];
-    struct spwd spw;
-#endif
+
+    /* 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 malisious 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;
@@ -49 +56 @@
     }
 
-    /* Malicious use like "sulogin /dev/sda"? */
-    if (!isatty(0) || !isatty(1) || !isatty(2)) {
-        logmode = LOGMODE_SYSLOG;
-        bb_error_msg_and_die("not a tty");
+    pwd = getpwuid(0);
+    if (!pwd) {
+        bb_error_msg_and_die("no password entry for root");
     }
 
-    /* Clear dangerous stuff, set PATH */
-    sanitize_env_if_suid();
-
-    pwd = getpwuid(0);
-    if (!pwd) {
-        goto auth_error;
-    }
-
-#if ENABLE_FEATURE_SHADOWPASSWDS
-    {
-        /* getspnam_r may return 0 yet set result to NULL.
-         * At least glibc 2.4 does this. Be extra paranoid here. */
-        struct spwd *result = NULL;
-        int r = getspnam_r(pwd->pw_name, &spw, buffer, sizeof(buffer), &result);
-        if (r || !result) {
-            goto auth_error;
-        }
-        pwd->pw_passwd = result->sp_pwdp;
-    }
-#endif
-
     while (1) {
-        char *encrypted;
         int r;
 
-        /* cp points to a static buffer that is zeroed every time */
-        cp = bb_ask(STDIN_FILENO, timeout,
-                "Give root password for system maintenance\n"
-                "(or type Control-D for normal startup):");
-
-        if (!cp || !*cp) {
-            bb_info_msg("Normal startup");
+        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;
         }
-        encrypted = pw_encrypt(cp, pwd->pw_passwd, 1);
-        r = strcmp(encrypted, pwd->pw_passwd);
-        free(encrypted);
-        if (r == 0) {
+        if (r > 0) {
             break;
         }
         bb_do_delay(LOGIN_FAIL_DELAY);
-        bb_info_msg("Login incorrect");
+        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");
 
     IF_SELINUX(renew_current_security_context());
@@ -113 +92 @@
     /* Exec login shell with no additional parameters. Never returns. */
     run_shell(shell, 1, NULL, NULL);
-
- auth_error:
-    bb_error_msg_and_die("no password entry for root");
 }