1 /* vi: set sw=4 ts=4: */
3 * Mini su implementation for busybox
5 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
11 #if ENABLE_FEATURE_SU_CHECKS_SHELLS
12 /* Return 1 if SHELL is a restricted shell (one not returned by
13 * getusershell), else 0, meaning it is a standard shell. */
14 static int restricted_shell(const char *shell)
19 /*setusershell(); - getusershell does it itself*/
20 while ((line = getusershell()) != NULL) {
21 if (/* *line != '#' && */ strcmp(line, shell) == 0) {
26 if (ENABLE_FEATURE_CLEAN_UP)
35 int su_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
36 int su_main(int argc UNUSED_PARAM, char **argv)
39 char *opt_shell = NULL;
40 char *opt_command = NULL;
41 const char *opt_username = "root";
43 uid_t cur_uid = getuid();
45 #if ENABLE_FEATURE_UTMP
50 flags = getopt32(argv, "mplc:s:", &opt_command, &opt_shell);
54 if (argv[0] && LONE_DASH(argv[0])) {
59 /* get user if specified */
61 opt_username = argv[0];
65 if (ENABLE_FEATURE_SU_SYSLOG) {
66 /* The utmp entry (via getlogin) is probably the best way to
67 * identify the user, especially if someone su's from a su-shell.
68 * But getlogin can fail -- usually due to lack of utmp entry.
69 * in this case resort to getpwuid. */
70 #if ENABLE_FEATURE_UTMP
72 if (getlogin_r(user_buf, sizeof(user_buf)) != 0)
75 pw = getpwuid(cur_uid);
76 old_user = pw ? xstrdup(pw->pw_name) : "";
78 tty = xmalloc_ttyname(2);
82 openlog(applet_name, 0, LOG_AUTH);
85 pw = xgetpwnam(opt_username);
87 if (cur_uid == 0 || correct_password(pw)) {
88 if (ENABLE_FEATURE_SU_SYSLOG)
89 syslog(LOG_NOTICE, "%c %s %s:%s",
90 '+', tty, old_user, opt_username);
92 if (ENABLE_FEATURE_SU_SYSLOG)
93 syslog(LOG_NOTICE, "%c %s %s:%s",
94 '-', tty, old_user, opt_username);
95 bb_error_msg_and_die("incorrect password");
98 if (ENABLE_FEATURE_CLEAN_UP && ENABLE_FEATURE_SU_SYSLOG) {
102 if (!opt_shell && (flags & SU_OPT_mp)) {
103 /* -s SHELL is not given, but "preserve env" opt is */
104 opt_shell = getenv("SHELL");
107 /* Make sure pw->pw_shell is non-NULL. It may be NULL when NEW_USER
108 * is a username that is retrieved via NIS (YP), that doesn't have
109 * a default shell listed. */
110 if (!pw->pw_shell || !pw->pw_shell[0])
111 pw->pw_shell = (char *)DEFAULT_SHELL;
113 #if ENABLE_FEATURE_SU_CHECKS_SHELLS
114 if (opt_shell && cur_uid != 0 && restricted_shell(pw->pw_shell)) {
115 /* The user being su'd to has a nonstandard shell, and so is
116 * probably a uucp account or has restricted access. Don't
117 * compromise the account by allowing access with a standard
119 bb_error_msg("using restricted shell");
122 /* else: user can run whatever he wants via "su -s PROG USER".
123 * This is safe since PROG is run under user's uid/gid. */
126 opt_shell = pw->pw_shell;
129 setup_environment(opt_shell,
130 ((flags & SU_OPT_l) / SU_OPT_l * SETUP_ENV_CLEARENV)
131 + (!(flags & SU_OPT_mp) * SETUP_ENV_CHANGEENV),
133 IF_SELINUX(set_current_security_context(NULL);)
136 run_shell(opt_shell, flags & SU_OPT_l, opt_command, (const char**)argv);
138 /* return EXIT_FAILURE; - not reached */