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