loginutils/addgroup.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * addgroup - add groups to /etc/group and /etc/gshadow
   4  *
   5  * Copyright (C) 1999 by Lineo, inc. and John Beppu
   6  * Copyright (C) 1999,2000,2001 by John Beppu <beppu@codepoet.org>
   7  * Copyright (C) 2007 by Tito Ragusa <farmatito@tiscali.it>
   8  *
   9  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  10  */
  11 //config:config ADDGROUP
  12 //config:       bool "addgroup (8.8 kb)"
  13 //config:       default y
  14 //config:       select LONG_OPTS
  15 //config:       help
  16 //config:       Utility for creating a new group account.
  17 //config:
  18 //config:config FEATURE_ADDUSER_TO_GROUP
  19 //config:       bool "Support adding users to groups"
  20 //config:       default y
  21 //config:       depends on ADDGROUP
  22 //config:       help
  23 //config:       If called with two non-option arguments,
  24 //config:       addgroup will add an existing user to an
  25 //config:       existing group.
  26
  27 //applet:IF_ADDGROUP(APPLET_NOEXEC(addgroup, addgroup, BB_DIR_USR_SBIN, BB_SUID_DROP, addgroup))
  28
  29 //kbuild:lib-$(CONFIG_ADDGROUP) += addgroup.o
  30
  31 //usage:#define addgroup_trivial_usage
  32 //usage:       "[-g GID] [-S] " IF_FEATURE_ADDUSER_TO_GROUP("[USER] ") "GROUP"
  33 //usage:#define addgroup_full_usage "\n\n"
  34 //usage:       "Add a group" IF_FEATURE_ADDUSER_TO_GROUP(" or add a user to a group") "\n"
  35 //usage:     "\n        -g GID  Group id"
  36 //usage:     "\n        -S      Create a system group"
  37
  38 #include "libbb.h"
  39
  40 #if CONFIG_LAST_SYSTEM_ID < CONFIG_FIRST_SYSTEM_ID
  41 #error Bad LAST_SYSTEM_ID or FIRST_SYSTEM_ID in .config
  42 #endif
  43 #if CONFIG_LAST_ID < CONFIG_LAST_SYSTEM_ID
  44 #error Bad LAST_ID or LAST_SYSTEM_ID in .config
  45 #endif
  46
  47 #define OPT_GID                       (1 << 0)
  48 #define OPT_SYSTEM_ACCOUNT            (1 << 1)
  49
  50 static void xgroup_study(struct group *g)
  51 {
  52         unsigned max = CONFIG_LAST_ID;
  53
  54         /* Make sure gr_name is unused */
  55         if (getgrnam(g->gr_name)) {
  56                 bb_error_msg_and_die("%s '%s' in use", "group", g->gr_name);
  57                 /* these format strings are reused in adduser and addgroup */
  58         }
  59
  60         /* if a specific gid is requested, the --system switch and */
  61         /* min and max values are overridden, and the range of valid */
  62         /* gid values is set to [0, INT_MAX] */
  63         if (!(option_mask32 & OPT_GID)) {
  64                 if (option_mask32 & OPT_SYSTEM_ACCOUNT) {
  65                         g->gr_gid = CONFIG_FIRST_SYSTEM_ID;
  66                         max = CONFIG_LAST_SYSTEM_ID;
  67                 } else {
  68                         g->gr_gid = CONFIG_LAST_SYSTEM_ID + 1;
  69                 }
  70         }
  71         /* Check if the desired gid is free
  72          * or find the first free one */
  73         while (1) {
  74                 if (!getgrgid(g->gr_gid)) {
  75                         return; /* found free group: return */
  76                 }
  77                 if (option_mask32 & OPT_GID) {
  78                         /* -g N, cannot pick gid other than N: error */
  79                         bb_error_msg_and_die("%s '%s' in use", "gid", itoa(g->gr_gid));
  80                         /* this format strings is reused in adduser and addgroup */
  81                 }
  82                 if (g->gr_gid == max) {
  83                         /* overflowed: error */
  84                         bb_error_msg_and_die("no %cids left", 'g');
  85                         /* this format string is reused in adduser and addgroup */
  86                 }
  87                 g->gr_gid++;
  88         }
  89 }
  90
  91 /* append a new user to the passwd file */
  92 static void new_group(char *group, gid_t gid)
  93 {
  94         struct group gr;
  95         char *p;
  96
  97         /* make sure gid and group haven't already been allocated */
  98         gr.gr_gid = gid;
  99         gr.gr_name = group;
 100         xgroup_study(&gr);
 101
 102         /* add entry to group */
 103         p = xasprintf("x:%u:", (unsigned) gr.gr_gid);
 104         if (update_passwd(bb_path_group_file, group, p, NULL) < 0)
 105                 exit_FAILURE();
 106         if (ENABLE_FEATURE_CLEAN_UP)
 107                 free(p);
 108 #if ENABLE_FEATURE_SHADOWPASSWDS
 109         /* /etc/gshadow fields:
 110          * 1. Group name.
 111          * 2. Encrypted password.
 112          *    If set, non-members of the group can join the group
 113          *    by typing the password for that group using the newgrp command.
 114          *    If the value is of this field ! then no user is allowed
 115          *    to access the group using the newgrp command. A value of !!
 116          *    is treated the same as a value of ! only it indicates
 117          *    that a password has never been set before. If the value is null,
 118          *    only group members can log into the group.
 119          * 3. Group administrators (comma delimited list).
 120          *    Group members listed here can add or remove group members
 121          *    using the gpasswd command.
 122          * 4. Group members (comma delimited list).
 123          */
 124         /* Ignore errors: if file is missing we assume admin doesn't want it */
 125         update_passwd(bb_path_gshadow_file, group, "!::", NULL);
 126 #endif
 127 }
 128
 129 //FIXME: upstream addgroup has no short options! NOT COMPATIBLE!
 130 static const char addgroup_longopts[] ALIGN1 =
 131                 "gid\0"                 Required_argument "g"
 132                 "system\0"              No_argument       "S"
 133                 ;
 134
 135 /*
 136  * addgroup will take a login_name as its first parameter.
 137  *
 138  * gid can be customized via command-line parameters.
 139  * If called with two non-option arguments, addgroup
 140  * will add an existing user to an existing group.
 141  */
 142 int addgroup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 143 int addgroup_main(int argc UNUSED_PARAM, char **argv)
 144 {
 145 #if ENABLE_FEATURE_ADDUSER_TO_GROUP
 146         unsigned opts;
 147 #endif
 148         const char *gid = "0";
 149
 150         /* need to be root */
 151         if (geteuid()) {
 152                 bb_simple_error_msg_and_die(bb_msg_perm_denied_are_you_root);
 153         }
 154         /* Syntax:
 155          *  addgroup group
 156          *  addgroup --gid num group
 157          *  addgroup user group
 158          * Check for min, max and missing args */
 159 #if ENABLE_FEATURE_ADDUSER_TO_GROUP
 160         opts =
 161 #endif
 162         getopt32long(argv, "^" "g:S" "\0" "-1:?2", addgroup_longopts,
 163                                 &gid
 164         );
 165         /* move past the commandline options */
 166         argv += optind;
 167         //argc -= optind;
 168
 169 #if ENABLE_FEATURE_ADDUSER_TO_GROUP
 170         if (argv[1]) {
 171                 struct group *gr;
 172
 173                 if (opts & OPT_GID) {
 174                         /* -g was there, but "addgroup -g num user group"
 175                          * is a no-no */
 176                         bb_show_usage();
 177                 }
 178
 179                 /* check if group and user exist */
 180                 xuname2uid(argv[0]); /* unknown user: exit */
 181                 gr = xgetgrnam(argv[1]); /* unknown group: exit */
 182                 /* check if user is already in this group */
 183                 for (; *(gr->gr_mem) != NULL; (gr->gr_mem)++) {
 184                         if (strcmp(argv[0], *(gr->gr_mem)) == 0) {
 185                                 /* user is already in group: do nothing */
 186                                 return EXIT_SUCCESS;
 187                         }
 188                 }
 189                 if (update_passwd(bb_path_group_file, argv[1], NULL, argv[0]) < 0) {
 190                         return EXIT_FAILURE;
 191                 }
 192 # if ENABLE_FEATURE_SHADOWPASSWDS
 193                 update_passwd(bb_path_gshadow_file, argv[1], NULL, argv[0]);
 194 # endif
 195         } else
 196 #endif /* ENABLE_FEATURE_ADDUSER_TO_GROUP */
 197         {
 198                 die_if_bad_username(argv[0]);
 199                 new_group(argv[0], xatou_range(gid, 0, CONFIG_LAST_ID));
 200         }
 201         /* Reached only on success */
 202         return EXIT_SUCCESS;
 203 }