LXR busybox/coreutils/id.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * Mini id implementation for busybox
   4 *
   5 * Copyright (C) 2000 by Randolph Chung <tausq@debian.org>
   6 * Copyright (C) 2008 by Tito Ragusa <farmatito@tiscali.it>
   7 *
   8 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   9 */
  10/* Hacked by Tito Ragusa (C) 2004 to handle usernames of whatever
  11 * length and to be more similar to GNU id.
  12 * -Z option support: by Yuichi Nakamura <ynakam@hitachisoft.jp>
  13 * Added -G option Tito Ragusa (C) 2008 for SUSv3.
  14 */
  15//config:config ID
  16//config:       bool "id (7 kb)"
  17//config:       default y
  18//config:       help
  19//config:       id displays the current user and group ID names.
  20//config:
  21//config:config GROUPS
  22//config:       bool "groups (6.7 kb)"
  23//config:       default y
  24//config:       help
  25//config:       Print the group names associated with current user id.
  26
  27//applet:IF_GROUPS(APPLET_NOEXEC(groups, id, BB_DIR_USR_BIN, BB_SUID_DROP, groups))
  28//applet:IF_ID(    APPLET_NOEXEC(id,     id, BB_DIR_USR_BIN, BB_SUID_DROP, id    ))
  29
  30//kbuild:lib-$(CONFIG_GROUPS) += id.o
  31//kbuild:lib-$(CONFIG_ID)     += id.o
  32
  33/* BB_AUDIT SUSv3 compliant. */
  34
  35//usage:#define id_trivial_usage
  36//usage:       "[-ugGnr"IF_SELINUX("Z")"] [USER]"
  37//usage:#define id_full_usage "\n\n"
  38//usage:       "Print information about USER or the current user\n"
  39//usage:        IF_SELINUX(
  40//usage:     "\n        -Z      Security context"
  41//usage:        )
  42//usage:     "\n        -u      User ID"
  43//usage:     "\n        -g      Group ID"
  44//usage:     "\n        -G      Supplementary group IDs"
  45//usage:     "\n        -n      Print names instead of numbers"
  46//usage:     "\n        -r      Print real ID instead of effective ID"
  47//usage:
  48//usage:#define id_example_usage
  49//usage:       "$ id\n"
  50//usage:       "uid=1000(andersen) gid=1000(andersen)\n"
  51
  52//usage:#define groups_trivial_usage
  53//usage:       "[USER]"
  54//usage:#define groups_full_usage "\n\n"
  55//usage:       "Print the groups USER is in"
  56//usage:
  57//usage:#define groups_example_usage
  58//usage:       "$ groups\n"
  59//usage:       "andersen lp dialout cdrom floppy\n"
  60
  61#include "libbb.h"
  62
  63/* This is a NOEXEC applet. Be very careful! */
  64
  65#if !ENABLE_USE_BB_PWD_GRP
  66#if defined(__UCLIBC__) && UCLIBC_VERSION < KERNEL_VERSION(0, 9, 30)
  67#error "Sorry, you need at least uClibc version 0.9.30 for id applet to build"
  68#endif
  69#endif
  70
  71enum {
  72        PRINT_REAL      = (1 << 0),
  73        NAME_NOT_NUMBER = (1 << 1),
  74        JUST_USER       = (1 << 2),
  75        JUST_GROUP      = (1 << 3),
  76        JUST_ALL_GROUPS = (1 << 4),
  77#if ENABLE_SELINUX
  78        JUST_CONTEXT    = (1 << 5),
  79#endif
  80};
  81
  82static int print_common(unsigned id, const char *name, const char *prefix)
  83{
  84        if (prefix) {
  85                printf("%s", prefix);
  86        }
  87        if (!(option_mask32 & NAME_NOT_NUMBER) || !name) {
  88                printf("%u", id);
  89        }
  90        if (!option_mask32 || (option_mask32 & NAME_NOT_NUMBER)) {
  91                if (name) {
  92                        printf(option_mask32 ? "%s" : "(%s)", name);
  93                } else {
  94                        /* Don't set error status flag in default mode */
  95                        if (option_mask32) {
  96                                if (ENABLE_DESKTOP)
  97                                        bb_error_msg("unknown ID %u", id);
  98                                return EXIT_FAILURE;
  99                        }
 100                }
 101        }
 102        return EXIT_SUCCESS;
 103}
 104
 105static int print_group(gid_t id, const char *prefix)
 106{
 107        return print_common(id, gid2group(id), prefix);
 108}
 109
 110static int print_user(uid_t id, const char *prefix)
 111{
 112        return print_common(id, uid2uname(id), prefix);
 113}
 114
 115/* On error set *n < 0 and return >= 0
 116 * If *n is too small, update it and return < 0
 117 * (ok to trash groups[] in both cases)
 118 * Otherwise fill in groups[] and return >= 0
 119 */
 120static int get_groups(const char *username, gid_t rgid, gid_t *groups, int *n)
 121{
 122        int m;
 123
 124        if (username) {
 125                /* If the user is a member of more than
 126                 * *n groups, then -1 is returned. Otherwise >= 0.
 127                 * (and no defined way of detecting errors?!) */
 128                m = getgrouplist(username, rgid, groups, n);
 129                /* I guess *n < 0 might indicate error. Anyway,
 130                 * malloc'ing -1 bytes won't be good, so: */
 131                if (*n < 0)
 132                        return 0;
 133                return m;
 134        }
 135
 136        *n = getgroups(*n, groups);
 137        if (*n >= 0)
 138                return *n;
 139        /* Error */
 140        if (errno == EINVAL) /* *n is too small? */
 141                *n = getgroups(0, groups); /* get needed *n */
 142        /* if *n >= 0, return -1 (got new *n), else return 0 (error): */
 143        return -(*n >= 0);
 144}
 145
 146int id_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 147int id_main(int argc UNUSED_PARAM, char **argv)
 148{
 149        uid_t ruid;
 150        gid_t rgid;
 151        uid_t euid;
 152        gid_t egid;
 153        unsigned opt;
 154        int i;
 155        int status = EXIT_SUCCESS;
 156        const char *prefix;
 157        const char *username;
 158#if ENABLE_SELINUX
 159        security_context_t scontext = NULL;
 160#endif
 161
 162        if (ENABLE_GROUPS && (!ENABLE_ID || applet_name[0] == 'g')) {
 163                /* TODO: coreutils groups prepend "USER : " prefix,
 164                 * and accept many usernames. Example:
 165                 * # groups root root
 166                 * root : root
 167                 * root : root
 168                 */
 169                opt = option_mask32 = getopt32(argv, "") | JUST_ALL_GROUPS | NAME_NOT_NUMBER;
 170        } else {
 171                /* Don't allow -n -r -nr -ug -rug -nug -rnug -uZ -gZ -GZ*/
 172                /* Don't allow more than one username */
 173                opt = getopt32(argv, "^"
 174                        "rnugG" IF_SELINUX("Z")
 175                        "\0"
 176                        "?1:u--g:g--u:G--u:u--G:g--G:G--g:r?ugG:n?ugG"
 177                        IF_SELINUX(":u--Z:Z--u:g--Z:Z--g:G--Z:Z--G")
 178                );
 179        }
 180
 181        username = argv[optind];
 182        if (username) {
 183                struct passwd *p = xgetpwnam(username);
 184                euid = ruid = p->pw_uid;
 185                egid = rgid = p->pw_gid;
 186        } else {
 187                egid = getegid();
 188                rgid = getgid();
 189                euid = geteuid();
 190                ruid = getuid();
 191        }
 192        /* JUST_ALL_GROUPS ignores -r PRINT_REAL flag even if man page for */
 193        /* id says: print the real ID instead of the effective ID, with -ugG */
 194        /* in fact in this case egid is always printed if egid != rgid */
 195        if (!opt || (opt & JUST_ALL_GROUPS)) {
 196                gid_t *groups;
 197                int n;
 198
 199                if (!opt) {
 200                        /* Default Mode */
 201                        status |= print_user(ruid, "uid=");
 202                        status |= print_group(rgid, " gid=");
 203                        if (euid != ruid)
 204                                status |= print_user(euid, " euid=");
 205                        if (egid != rgid)
 206                                status |= print_group(egid, " egid=");
 207                } else {
 208                        /* JUST_ALL_GROUPS */
 209                        status |= print_group(rgid, NULL);
 210                        if (egid != rgid)
 211                                status |= print_group(egid, " ");
 212                }
 213                /* We are supplying largish buffer, trying
 214                 * to not run get_groups() twice. That might be slow
 215                 * ("user database in remote SQL server" case) */
 216                groups = xmalloc(64 * sizeof(groups[0]));
 217                n = 64;
 218                if (get_groups(username, rgid, groups, &n) < 0) {
 219                        /* Need bigger buffer after all */
 220                        groups = xrealloc(groups, n * sizeof(groups[0]));
 221                        get_groups(username, rgid, groups, &n);
 222                }
 223                if (n > 0) {
 224                        /* Print the list */
 225                        prefix = " groups=";
 226                        for (i = 0; i < n; i++) {
 227                                if (opt && (groups[i] == rgid || groups[i] == egid))
 228                                        continue;
 229                                status |= print_group(groups[i], opt ? " " : prefix);
 230                                prefix = ",";
 231                        }
 232                } else if (n < 0) { /* error in get_groups() */
 233                        if (ENABLE_DESKTOP)
 234                                bb_simple_error_msg_and_die("can't get groups");
 235                        return EXIT_FAILURE;
 236                }
 237                if (ENABLE_FEATURE_CLEAN_UP)
 238                        free(groups);
 239#if ENABLE_SELINUX
 240                if (is_selinux_enabled()) {
 241                        if (getcon(&scontext) == 0)
 242                                printf(" context=%s", scontext);
 243                }
 244#endif
 245        } else if (opt & PRINT_REAL) {
 246                euid = ruid;
 247                egid = rgid;
 248        }
 249
 250        if (opt & JUST_USER)
 251                status |= print_user(euid, NULL);
 252        else if (opt & JUST_GROUP)
 253                status |= print_group(egid, NULL);
 254#if ENABLE_SELINUX
 255        else if (opt & JUST_CONTEXT) {
 256                selinux_or_die();
 257                if (username || getcon(&scontext)) {
 258                        bb_error_msg_and_die("can't get process context%s",
 259                                username ? " for a different user" : "");
 260                }
 261                fputs_stdout(scontext);
 262        }
 263        /* freecon(NULL) seems to be harmless */
 264        if (ENABLE_FEATURE_CLEAN_UP)
 265                freecon(scontext);
 266#endif
 267        bb_putchar('\n');
 268        fflush_stdout_and_exit(status);
 269}
 270