[821] | 1 | /* vi: set sw=4 ts=4: */
|
---|
| 2 | /*
|
---|
[2725] | 3 | * Mini su implementation for busybox
|
---|
[1765] | 4 | *
|
---|
[2725] | 5 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
|
---|
[1765] | 6 | */
|
---|
[821] | 7 |
|
---|
[1765] | 8 | #include "libbb.h"
|
---|
[821] | 9 | #include <syslog.h>
|
---|
| 10 |
|
---|
[2725] | 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)
|
---|
| 15 | {
|
---|
| 16 | char *line;
|
---|
| 17 | int result = 1;
|
---|
| 18 |
|
---|
| 19 | /*setusershell(); - getusershell does it itself*/
|
---|
| 20 | while ((line = getusershell()) != NULL) {
|
---|
| 21 | if (/* *line != '#' && */ strcmp(line, shell) == 0) {
|
---|
| 22 | result = 0;
|
---|
| 23 | break;
|
---|
| 24 | }
|
---|
| 25 | }
|
---|
| 26 | if (ENABLE_FEATURE_CLEAN_UP)
|
---|
| 27 | endusershell();
|
---|
| 28 | return result;
|
---|
| 29 | }
|
---|
| 30 | #endif
|
---|
| 31 |
|
---|
[1765] | 32 | #define SU_OPT_mp (3)
|
---|
[2725] | 33 | #define SU_OPT_l (4)
|
---|
[821] | 34 |
|
---|
[2725] | 35 | int su_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
|
---|
| 36 | int su_main(int argc UNUSED_PARAM, char **argv)
|
---|
[821] | 37 | {
|
---|
[1765] | 38 | unsigned flags;
|
---|
| 39 | char *opt_shell = NULL;
|
---|
| 40 | char *opt_command = NULL;
|
---|
| 41 | const char *opt_username = "root";
|
---|
[821] | 42 | struct passwd *pw;
|
---|
| 43 | uid_t cur_uid = getuid();
|
---|
| 44 | const char *tty;
|
---|
[2725] | 45 | char user_buf[64];
|
---|
| 46 | const char *old_user;
|
---|
[821] | 47 |
|
---|
[1765] | 48 | flags = getopt32(argv, "mplc:s:", &opt_command, &opt_shell);
|
---|
[2725] | 49 | //argc -= optind;
|
---|
[1765] | 50 | argv += optind;
|
---|
[821] | 51 |
|
---|
[2725] | 52 | if (argv[0] && LONE_DASH(argv[0])) {
|
---|
[821] | 53 | flags |= SU_OPT_l;
|
---|
[1765] | 54 | argv++;
|
---|
| 55 | }
|
---|
[821] | 56 |
|
---|
| 57 | /* get user if specified */
|
---|
[2725] | 58 | if (argv[0]) {
|
---|
[1765] | 59 | opt_username = argv[0];
|
---|
| 60 | argv++;
|
---|
| 61 | }
|
---|
[821] | 62 |
|
---|
[1765] | 63 | if (ENABLE_FEATURE_SU_SYSLOG) {
|
---|
[2725] | 64 | /* The utmp entry (via getlogin) is probably the best way to
|
---|
| 65 | * identify the user, especially if someone su's from a su-shell.
|
---|
| 66 | * But getlogin can fail -- usually due to lack of utmp entry.
|
---|
| 67 | * in this case resort to getpwuid. */
|
---|
| 68 | #if ENABLE_FEATURE_UTMP
|
---|
| 69 | old_user = user_buf;
|
---|
| 70 | if (getlogin_r(user_buf, sizeof(user_buf)) != 0)
|
---|
| 71 | #endif
|
---|
| 72 | {
|
---|
| 73 | pw = getpwuid(cur_uid);
|
---|
| 74 | old_user = pw ? xstrdup(pw->pw_name) : "";
|
---|
| 75 | }
|
---|
| 76 | tty = xmalloc_ttyname(2);
|
---|
| 77 | if (!tty) {
|
---|
| 78 | tty = "none";
|
---|
| 79 | }
|
---|
[1765] | 80 | openlog(applet_name, 0, LOG_AUTH);
|
---|
[821] | 81 | }
|
---|
| 82 |
|
---|
[2725] | 83 | pw = xgetpwnam(opt_username);
|
---|
[821] | 84 |
|
---|
[2725] | 85 | if (cur_uid == 0 || correct_password(pw)) {
|
---|
[1765] | 86 | if (ENABLE_FEATURE_SU_SYSLOG)
|
---|
| 87 | syslog(LOG_NOTICE, "%c %s %s:%s",
|
---|
| 88 | '+', tty, old_user, opt_username);
|
---|
[821] | 89 | } else {
|
---|
[1765] | 90 | if (ENABLE_FEATURE_SU_SYSLOG)
|
---|
| 91 | syslog(LOG_NOTICE, "%c %s %s:%s",
|
---|
| 92 | '-', tty, old_user, opt_username);
|
---|
| 93 | bb_error_msg_and_die("incorrect password");
|
---|
[821] | 94 | }
|
---|
| 95 |
|
---|
[1765] | 96 | if (ENABLE_FEATURE_CLEAN_UP && ENABLE_FEATURE_SU_SYSLOG) {
|
---|
| 97 | closelog();
|
---|
| 98 | }
|
---|
[821] | 99 |
|
---|
[2725] | 100 | if (!opt_shell && (flags & SU_OPT_mp)) {
|
---|
| 101 | /* -s SHELL is not given, but "preserve env" opt is */
|
---|
[1765] | 102 | opt_shell = getenv("SHELL");
|
---|
[2725] | 103 | }
|
---|
[821] | 104 |
|
---|
[2725] | 105 | /* Make sure pw->pw_shell is non-NULL. It may be NULL when NEW_USER
|
---|
| 106 | * is a username that is retrieved via NIS (YP), that doesn't have
|
---|
| 107 | * a default shell listed. */
|
---|
| 108 | if (!pw->pw_shell || !pw->pw_shell[0])
|
---|
| 109 | pw->pw_shell = (char *)DEFAULT_SHELL;
|
---|
| 110 |
|
---|
[1765] | 111 | #if ENABLE_FEATURE_SU_CHECKS_SHELLS
|
---|
[2725] | 112 | if (opt_shell && cur_uid != 0 && restricted_shell(pw->pw_shell)) {
|
---|
[821] | 113 | /* The user being su'd to has a nonstandard shell, and so is
|
---|
[2725] | 114 | * probably a uucp account or has restricted access. Don't
|
---|
| 115 | * compromise the account by allowing access with a standard
|
---|
| 116 | * shell. */
|
---|
[1765] | 117 | bb_error_msg("using restricted shell");
|
---|
[2725] | 118 | opt_shell = NULL;
|
---|
[821] | 119 | }
|
---|
[2725] | 120 | /* else: user can run whatever he wants via "su -s PROG USER".
|
---|
| 121 | * This is safe since PROG is run under user's uid/gid. */
|
---|
[1765] | 122 | #endif
|
---|
| 123 | if (!opt_shell)
|
---|
[821] | 124 | opt_shell = pw->pw_shell;
|
---|
| 125 |
|
---|
[1765] | 126 | change_identity(pw);
|
---|
[2725] | 127 | setup_environment(opt_shell,
|
---|
| 128 | ((flags & SU_OPT_l) / SU_OPT_l * SETUP_ENV_CLEARENV)
|
---|
| 129 | + (!(flags & SU_OPT_mp) * SETUP_ENV_CHANGEENV),
|
---|
| 130 | pw);
|
---|
| 131 | IF_SELINUX(set_current_security_context(NULL);)
|
---|
[821] | 132 |
|
---|
[1765] | 133 | /* Never returns */
|
---|
| 134 | run_shell(opt_shell, flags & SU_OPT_l, opt_command, (const char**)argv);
|
---|
| 135 |
|
---|
[2725] | 136 | /* return EXIT_FAILURE; - not reached */
|
---|
[821] | 137 | }
|
---|