hush: fix incorrect PS2 dispaly and trap handling while reading command

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

diff --git a/loginutils/su.c b/loginutils/su.c
index af25655fd4986ca4eba4523917c42b9e26a0ceb1..72dd0f06f0b6a59ed1fd2885177aac8c25af4deb 100644 (file)
--- a/loginutils/su.c
+++ b/loginutils/su.c
@@ -1,32 +1,46 @@
 /* vi: set sw=4 ts=4: */
 /*
- *  Mini su implementation for busybox
+ * Mini su implementation for busybox
  *
- *  Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
 
 #include "libbb.h"
 #include <syslog.h>
 
+//usage:#define su_trivial_usage
+//usage:       "[OPTIONS] [-] [USER]"
+//usage:#define su_full_usage "\n\n"
+//usage:       "Run shell under USER (by default, root)\n"
+//usage:     "\nOptions:"
+//usage:     "\n       -,-l    Clear environment, run shell as login shell"
+//usage:     "\n       -p,-m   Do not set new $HOME, $SHELL, $USER, $LOGNAME"
+//usage:     "\n       -c CMD  Command to pass to 'sh -c'"
+//usage:     "\n       -s SH   Shell to use instead of user's default"
+
 #if ENABLE_FEATURE_SU_CHECKS_SHELLS
 /* Return 1 if SHELL is a restricted shell (one not returned by
-   getusershell), else 0, meaning it is a standard shell.  */
+ * getusershell), else 0, meaning it is a standard shell.  */
 static int restricted_shell(const char *shell)
 {
        char *line;
+       int result = 1;
 
        /*setusershell(); - getusershell does it itself*/
        while ((line = getusershell()) != NULL) {
-               if (/* *line != '#' && */ strcmp(line, shell) == 0)
-                       return 0;
+               if (/* *line != '#' && */ strcmp(line, shell) == 0) {
+                       result = 0;
+                       break;
+               }
        }
-       endusershell();
-       return 1;
+       if (ENABLE_FEATURE_CLEAN_UP)
+               endusershell();
+       return result;
 }
 #endif
 
 #define SU_OPT_mp (3)
-#define SU_OPT_l (4)
+#define SU_OPT_l  (4)
 
 int su_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int su_main(int argc UNUSED_PARAM, char **argv)
@@ -38,7 +52,10 @@ int su_main(int argc UNUSED_PARAM, char **argv)
        struct passwd *pw;
        uid_t cur_uid = getuid();
        const char *tty;
-       char *old_user;
+#if ENABLE_FEATURE_UTMP
+       char user_buf[64];
+#endif
+       const char *old_user;
 
        flags = getopt32(argv, "mplc:s:", &opt_command, &opt_shell);
        //argc -= optind;
@@ -56,21 +73,18 @@ int su_main(int argc UNUSED_PARAM, char **argv)
        }
 
        if (ENABLE_FEATURE_SU_SYSLOG) {
-               /* The utmp entry (via getlogin) is probably the best way to identify
-                * the user, especially if someone su's from a su-shell.
+               /* The utmp entry (via getlogin) is probably the best way to
+                * identify the user, especially if someone su's from a su-shell.
                 * But getlogin can fail -- usually due to lack of utmp entry.
                 * in this case resort to getpwuid.  */
-               const char *user;
 #if ENABLE_FEATURE_UTMP
-               char user_buf[64];
-               user = user_buf;
+               old_user = user_buf;
                if (getlogin_r(user_buf, sizeof(user_buf)) != 0)
 #endif
                {
                        pw = getpwuid(cur_uid);
-                       user = pw ? pw->pw_name : "";
+                       old_user = pw ? xstrdup(pw->pw_name) : "";
                }
-               old_user = xstrdup(user);
                tty = xmalloc_ttyname(2);
                if (!tty) {
                        tty = "none";
@@ -80,13 +94,7 @@ int su_main(int argc UNUSED_PARAM, char **argv)
 
        pw = xgetpwnam(opt_username);
 
-       /* Make sure pw->pw_shell is non-NULL.  It may be NULL when NEW_USER
-          is a username that is retrieved via NIS (YP), but that doesn't have
-          a default shell listed.  */
-       if (!pw->pw_shell || !pw->pw_shell[0])
-               pw->pw_shell = (char *)DEFAULT_SHELL;
-
-       if ((cur_uid == 0) || correct_password(pw)) {
+       if (cur_uid == 0 || correct_password(pw)) {
                if (ENABLE_FEATURE_SU_SYSLOG)
                        syslog(LOG_NOTICE, "%c %s %s:%s",
                                '+', tty, old_user, opt_username);
@@ -99,21 +107,24 @@ int su_main(int argc UNUSED_PARAM, char **argv)
 
        if (ENABLE_FEATURE_CLEAN_UP && ENABLE_FEATURE_SU_SYSLOG) {
                closelog();
-               free(old_user);
        }
 
-       if (!opt_shell && (flags & SU_OPT_mp))
+       if (!opt_shell && (flags & SU_OPT_mp)) {
+               /* -s SHELL is not given, but "preserve env" opt is */
                opt_shell = getenv("SHELL");
+       }
 
 #if ENABLE_FEATURE_SU_CHECKS_SHELLS
-       if (opt_shell && cur_uid != 0 && restricted_shell(pw->pw_shell)) {
+       if (opt_shell && cur_uid != 0 && pw->pw_shell && restricted_shell(pw->pw_shell)) {
                /* The user being su'd to has a nonstandard shell, and so is
-                  probably a uucp account or has restricted access.  Don't
-                  compromise the account by allowing access with a standard
-                  shell.  */
+                * probably a uucp account or has restricted access.  Don't
+                * compromise the account by allowing access with a standard
+                * shell.  */
                bb_error_msg("using restricted shell");
-               opt_shell = NULL;
+               opt_shell = NULL; /* ignore -s PROG */
        }
+       /* else: user can run whatever he wants via "su -s PROG USER".
+        * This is safe since PROG is run under user's uid/gid. */
 #endif
        if (!opt_shell)
                opt_shell = pw->pw_shell;