/* 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: "\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. */
+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) {
+ result = 0;
+ break;
+ }
+ }
+ 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)
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;
}
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. */
- old_user = xstrdup(USE_FEATURE_UTMP(getlogin() ? : ) (pw = getpwuid(cur_uid)) ? pw->pw_name : "");
- tty = ttyname(2) ? : "none";
+ /* 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. */
+#if ENABLE_FEATURE_UTMP
+ old_user = user_buf;
+ if (getlogin_r(user_buf, sizeof(user_buf)) != 0)
+#endif
+ {
+ pw = getpwuid(cur_uid);
+ old_user = pw ? xstrdup(pw->pw_name) : "";
+ }
+ 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 (cur_uid == 0 || ask_and_check_password(pw) > 0) {
if (ENABLE_FEATURE_SU_SYSLOG)
syslog(LOG_NOTICE, "%c %s %s:%s",
'+', tty, old_user, opt_username);
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 && 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;
change_identity(pw);
- /* setup_environment params: shell, clear_env, change_env, pw */
- setup_environment(opt_shell, flags & SU_OPT_l, !(flags & SU_OPT_mp), pw);
- USE_SELINUX(set_current_security_context(NULL);)
+ setup_environment(opt_shell,
+ ((flags & SU_OPT_l) / SU_OPT_l * SETUP_ENV_CLEARENV)
+ + (!(flags & SU_OPT_mp) * SETUP_ENV_CHANGEENV)
+ + (!(flags & SU_OPT_l) * SETUP_ENV_NO_CHDIR),
+ pw);
+ IF_SELINUX(set_current_security_context(NULL);)
/* Never returns */
run_shell(opt_shell, flags & SU_OPT_l, opt_command, (const char**)argv);