| 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * Mini su implementation for busybox
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| 4 | *
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| 5 | * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
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| 6 | */
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| 7 |
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| 8 | #include "libbb.h"
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| 9 | #include <syslog.h>
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| 10 |
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| 11 | #define SU_OPT_mp (3)
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| 12 | #define SU_OPT_l (4)
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| 13 |
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| 14 | int su_main(int argc, char **argv);
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| 15 | int su_main(int argc, char **argv)
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| 16 | {
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| 17 | unsigned flags;
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| 18 | char *opt_shell = NULL;
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| 19 | char *opt_command = NULL;
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| 20 | const char *opt_username = "root";
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| 21 | struct passwd *pw;
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| 22 | uid_t cur_uid = getuid();
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| 23 | const char *tty;
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| 24 | char *old_user;
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| 25 |
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| 26 | flags = getopt32(argv, "mplc:s:", &opt_command, &opt_shell);
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| 27 | argc -= optind;
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| 28 | argv += optind;
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| 29 |
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| 30 | if (argc && LONE_DASH(argv[0])) {
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| 31 | flags |= SU_OPT_l;
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| 32 | argc--;
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| 33 | argv++;
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| 34 | }
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| 35 |
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| 36 | /* get user if specified */
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| 37 | if (argc) {
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| 38 | opt_username = argv[0];
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| 39 | // argc--;
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| 40 | argv++;
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| 41 | }
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| 42 |
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| 43 | if (ENABLE_FEATURE_SU_SYSLOG) {
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| 44 | /* The utmp entry (via getlogin) is probably the best way to identify
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| 45 | the user, especially if someone su's from a su-shell.
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| 46 | But getlogin can fail -- usually due to lack of utmp entry.
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| 47 | in this case resort to getpwuid. */
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| 48 | old_user = xstrdup(USE_FEATURE_UTMP(getlogin() ? : ) (pw = getpwuid(cur_uid)) ? pw->pw_name : "");
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| 49 | tty = ttyname(2) ? : "none";
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| 50 | openlog(applet_name, 0, LOG_AUTH);
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| 51 | }
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| 52 |
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| 53 | pw = getpwnam(opt_username);
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| 54 | if (!pw)
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| 55 | bb_error_msg_and_die("unknown id: %s", opt_username);
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| 56 |
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| 57 | /* Make sure pw->pw_shell is non-NULL. It may be NULL when NEW_USER
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| 58 | is a username that is retrieved via NIS (YP), but that doesn't have
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| 59 | a default shell listed. */
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| 60 | if (!pw->pw_shell || !pw->pw_shell[0])
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| 61 | pw->pw_shell = (char *)DEFAULT_SHELL;
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| 62 |
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| 63 | if ((cur_uid == 0) || correct_password(pw)) {
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| 64 | if (ENABLE_FEATURE_SU_SYSLOG)
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| 65 | syslog(LOG_NOTICE, "%c %s %s:%s",
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| 66 | '+', tty, old_user, opt_username);
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| 67 | } else {
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| 68 | if (ENABLE_FEATURE_SU_SYSLOG)
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| 69 | syslog(LOG_NOTICE, "%c %s %s:%s",
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| 70 | '-', tty, old_user, opt_username);
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| 71 | bb_error_msg_and_die("incorrect password");
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| 72 | }
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| 73 |
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| 74 | if (ENABLE_FEATURE_CLEAN_UP && ENABLE_FEATURE_SU_SYSLOG) {
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| 75 | closelog();
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| 76 | free(old_user);
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| 77 | }
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| 78 |
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| 79 | if (!opt_shell && (flags & SU_OPT_mp))
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| 80 | opt_shell = getenv("SHELL");
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| 81 |
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| 82 | #if ENABLE_FEATURE_SU_CHECKS_SHELLS
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| 83 | if (opt_shell && cur_uid && restricted_shell(pw->pw_shell)) {
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| 84 | /* The user being su'd to has a nonstandard shell, and so is
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| 85 | probably a uucp account or has restricted access. Don't
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| 86 | compromise the account by allowing access with a standard
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| 87 | shell. */
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| 88 | bb_error_msg("using restricted shell");
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| 89 | opt_shell = 0;
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| 90 | }
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| 91 | #endif
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| 92 | if (!opt_shell)
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| 93 | opt_shell = pw->pw_shell;
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| 94 |
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| 95 | change_identity(pw);
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| 96 | setup_environment(opt_shell, flags & SU_OPT_l, !(flags & SU_OPT_mp), pw);
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| 97 | USE_SELINUX(set_current_security_context(NULL);)
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| 98 |
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| 99 | /* Never returns */
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| 100 | run_shell(opt_shell, flags & SU_OPT_l, opt_command, (const char**)argv);
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| 101 |
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| 102 | return EXIT_FAILURE;
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| 103 | }
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