/* vi: set sw=4 ts=4: */ /* * Mini su implementation for busybox * * Licensed under the GPL v2 or later, see the file LICENSE in this tarball. */ #include "libbb.h" #include <syslog.h> #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. */ static int restricted_shell(const char *shell) { char *line; /*setusershell(); - getusershell does it itself*/ while ((line = getusershell()) != NULL) { if (/* *line != '#' && */ strcmp(line, shell) == 0) return 0; } endusershell(); return 1; } #endif #define SU_OPT_mp (3) #define SU_OPT_l (4) int su_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int su_main(int argc UNUSED_PARAM, char **argv) { unsigned flags; char *opt_shell = NULL; char *opt_command = NULL; const char *opt_username = "root"; struct passwd *pw; uid_t cur_uid = getuid(); const char *tty; char *old_user; flags = getopt32(argv, "mplc:s:", &opt_command, &opt_shell); //argc -= optind; argv += optind; if (argv[0] && LONE_DASH(argv[0])) { flags |= SU_OPT_l; argv++; } /* get user if specified */ if (argv[0]) { opt_username = argv[0]; 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. * 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; if (getlogin_r(user_buf, sizeof(user_buf)) != 0) #endif { pw = getpwuid(cur_uid); user = pw ? pw->pw_name : ""; } old_user = xstrdup(user); tty = xmalloc_ttyname(2); if (!tty) { tty = "none"; } openlog(applet_name, 0, LOG_AUTH); } 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 (ENABLE_FEATURE_SU_SYSLOG) syslog(LOG_NOTICE, "%c %s %s:%s", '+', tty, old_user, opt_username); } else { if (ENABLE_FEATURE_SU_SYSLOG) syslog(LOG_NOTICE, "%c %s %s:%s", '-', tty, old_user, opt_username); bb_error_msg_and_die("incorrect password"); } if (ENABLE_FEATURE_CLEAN_UP && ENABLE_FEATURE_SU_SYSLOG) { closelog(); free(old_user); } if (!opt_shell && (flags & SU_OPT_mp)) opt_shell = getenv("SHELL"); #if ENABLE_FEATURE_SU_CHECKS_SHELLS if (opt_shell && cur_uid != 0 && 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. */ bb_error_msg("using restricted shell"); opt_shell = NULL; } #endif if (!opt_shell) opt_shell = pw->pw_shell; change_identity(pw); setup_environment(opt_shell, ((flags & SU_OPT_l) / SU_OPT_l * SETUP_ENV_CLEARENV) + (!(flags & SU_OPT_mp) * SETUP_ENV_CHANGEENV), pw); IF_SELINUX(set_current_security_context(NULL);) /* Never returns */ run_shell(opt_shell, flags & SU_OPT_l, opt_command, (const char**)argv); /* return EXIT_FAILURE; - not reached */ }