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 (7.1 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 (6.8 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
  71 enum {
  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
  82 static 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
 105 static int print_group(gid_t id, const char *prefix)
 106 {
 107         return print_common(id, gid2group(id), prefix);
 108 }
 109
 110 static 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  */
 120 static 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
 146 int id_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 147 int 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 }