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/* vi: set sw=4 ts=4: */
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* Mini id implementation for busybox
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* Copyright (C) 2000 by Randolph Chung <tausq@debian.org>
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* Copyright (C) 2008 by Tito Ragusa <farmatito@tiscali.it>
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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/* Hacked by Tito Ragusa (C) 2004 to handle usernames of whatever
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* length and to be more similar to GNU id.
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* -Z option support: by Yuichi Nakamura <ynakam@hitachisoft.jp>
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* Added -G option Tito Ragusa (C) 2008 for SUSv3.
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//config: bool "id (7 kb)"
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//config: id displays the current user and group ID names.
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//config:config GROUPS
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//config: bool "groups (6.7 kb)"
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//config: Print the group names associated with current user id.
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//applet:IF_GROUPS(APPLET_NOEXEC(groups, id, BB_DIR_USR_BIN, BB_SUID_DROP, groups))
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//applet:IF_ID( APPLET_NOEXEC(id, id, BB_DIR_USR_BIN, BB_SUID_DROP, id ))
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//kbuild:lib-$(CONFIG_GROUPS) += id.o
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//kbuild:lib-$(CONFIG_ID) += id.o
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/* BB_AUDIT SUSv3 compliant. */
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//usage:#define id_trivial_usage
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//usage: "[OPTIONS] [USER]"
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//usage:#define id_full_usage "\n\n"
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//usage: "Print information about USER or the current user\n"
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//usage: "\n -Z Security context"
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//usage: "\n -u User ID"
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//usage: "\n -g Group ID"
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//usage: "\n -G Supplementary group IDs"
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//usage: "\n -n Print names instead of numbers"
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//usage: "\n -r Print real ID instead of effective ID"
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//usage:#define id_example_usage
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//usage: "uid=1000(andersen) gid=1000(andersen)\n"
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//usage:#define groups_trivial_usage
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//usage:#define groups_full_usage "\n\n"
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//usage: "Print the group memberships of USER or for the current process"
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//usage:#define groups_example_usage
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//usage: "andersen lp dialout cdrom floppy\n"
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/* This is a NOEXEC applet. Be very careful! */
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#if !ENABLE_USE_BB_PWD_GRP
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#if defined(__UCLIBC__) && UCLIBC_VERSION < KERNEL_VERSION(0, 9, 30)
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#error "Sorry, you need at least uClibc version 0.9.30 for id applet to build"
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PRINT_REAL = (1 << 0),
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NAME_NOT_NUMBER = (1 << 1),
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JUST_GROUP = (1 << 3),
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JUST_ALL_GROUPS = (1 << 4),
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JUST_CONTEXT = (1 << 5),
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static int print_common(unsigned id, const char *name, const char *prefix)
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if (!(option_mask32 & NAME_NOT_NUMBER) || !name) {
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if (!option_mask32 || (option_mask32 & NAME_NOT_NUMBER)) {
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printf(option_mask32 ? "%s" : "(%s)", name);
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/* Don't set error status flag in default mode */
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bb_error_msg("unknown ID %u", id);
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static int print_group(gid_t id, const char *prefix)
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return print_common(id, gid2group(id), prefix);
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static int print_user(uid_t id, const char *prefix)
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return print_common(id, uid2uname(id), prefix);
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/* On error set *n < 0 and return >= 0
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* If *n is too small, update it and return < 0
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* (ok to trash groups[] in both cases)
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* Otherwise fill in groups[] and return >= 0
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static int get_groups(const char *username, gid_t rgid, gid_t *groups, int *n)
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/* If the user is a member of more than
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* *n groups, then -1 is returned. Otherwise >= 0.
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* (and no defined way of detecting errors?!) */
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m = getgrouplist(username, rgid, groups, n);
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/* I guess *n < 0 might indicate error. Anyway,
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* malloc'ing -1 bytes won't be good, so: */
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*n = getgroups(*n, groups);
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if (errno == EINVAL) /* *n is too small? */
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*n = getgroups(0, groups); /* get needed *n */
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/* if *n >= 0, return -1 (got new *n), else return 0 (error): */
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int id_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int id_main(int argc UNUSED_PARAM, char **argv)
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int status = EXIT_SUCCESS;
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const char *username;
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security_context_t scontext = NULL;
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if (ENABLE_GROUPS && (!ENABLE_ID || applet_name[0] == 'g')) {
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/* TODO: coreutils groups prepend "USER : " prefix,
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* and accept many usernames. Example:
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opt = option_mask32 = getopt32(argv, "") | JUST_ALL_GROUPS | NAME_NOT_NUMBER;
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/* Don't allow -n -r -nr -ug -rug -nug -rnug -uZ -gZ -GZ*/
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/* Don't allow more than one username */
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opt = getopt32(argv, "^"
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"rnugG" IF_SELINUX("Z")
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"?1:u--g:g--u:G--u:u--G:g--G:G--g:r?ugG:n?ugG"
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IF_SELINUX(":u--Z:Z--u:g--Z:Z--g:G--Z:Z--G")
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username = argv[optind];
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struct passwd *p = xgetpwnam(username);
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euid = ruid = p->pw_uid;
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egid = rgid = p->pw_gid;
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/* JUST_ALL_GROUPS ignores -r PRINT_REAL flag even if man page for */
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/* id says: print the real ID instead of the effective ID, with -ugG */
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/* in fact in this case egid is always printed if egid != rgid */
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if (!opt || (opt & JUST_ALL_GROUPS)) {
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status |= print_user(ruid, "uid=");
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status |= print_group(rgid, " gid=");
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status |= print_user(euid, " euid=");
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status |= print_group(egid, " egid=");
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/* JUST_ALL_GROUPS */
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status |= print_group(rgid, NULL);
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status |= print_group(egid, " ");
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/* We are supplying largish buffer, trying
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* to not run get_groups() twice. That might be slow
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* ("user database in remote SQL server" case) */
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groups = xmalloc(64 * sizeof(groups[0]));
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if (get_groups(username, rgid, groups, &n) < 0) {
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/* Need bigger buffer after all */
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groups = xrealloc(groups, n * sizeof(groups[0]));
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get_groups(username, rgid, groups, &n);
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for (i = 0; i < n; i++) {
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if (opt && (groups[i] == rgid || groups[i] == egid))
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status |= print_group(groups[i], opt ? " " : prefix);
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} else if (n < 0) { /* error in get_groups() */
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bb_error_msg_and_die("can't get groups");
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if (ENABLE_FEATURE_CLEAN_UP)
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if (is_selinux_enabled()) {
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if (getcon(&scontext) == 0)
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printf(" context=%s", scontext);
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} else if (opt & PRINT_REAL) {
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status |= print_user(euid, NULL);
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else if (opt & JUST_GROUP)
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status |= print_group(egid, NULL);
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else if (opt & JUST_CONTEXT) {
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if (username || getcon(&scontext)) {
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bb_error_msg_and_die("can't get process context%s",
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username ? " for a different user" : "");
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fputs(scontext, stdout);
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/* freecon(NULL) seems to be harmless */
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if (ENABLE_FEATURE_CLEAN_UP)
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fflush_stdout_and_exit(status);