lib/kadm5/acl.c

   1 /*
   2  * Copyright (c) 1997 - 2001 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include "kadm5_locl.h"
  35
  36 RCSID("$Id$");
  37
  38 static struct units acl_units[] = {
  39     { "all",            KADM5_PRIV_ALL },
  40     { "change-password",KADM5_PRIV_CPW },
  41     { "cpw",            KADM5_PRIV_CPW },
  42     { "list",           KADM5_PRIV_LIST },
  43     { "delete",         KADM5_PRIV_DELETE },
  44     { "modify",         KADM5_PRIV_MODIFY },
  45     { "add",            KADM5_PRIV_ADD },
  46     { "get",            KADM5_PRIV_GET },
  47     { "get-keys",       KADM5_PRIV_GET_KEYS },
  48     { NULL,             0 }
  49 };
  50
  51 kadm5_ret_t
  52 _kadm5_string_to_privs(const char *s, uint32_t* privs)
  53 {
  54     int flags;
  55     flags = parse_flags(s, acl_units, 0);
  56     if(flags < 0)
  57         return KADM5_FAILURE;
  58     *privs = flags;
  59     return 0;
  60 }
  61
  62 kadm5_ret_t
  63 _kadm5_privs_to_string(uint32_t privs, char *string, size_t len)
  64 {
  65     if(privs == 0)
  66         strlcpy(string, "none", len);
  67     else
  68         unparse_flags(privs, acl_units + 1, string, len);
  69     return 0;
  70 }
  71
  72 /*
  73  * retrieve the right for the current caller on `princ' (NULL means all)
  74  * and store them in `ret_flags'
  75  * return 0 or an error.
  76  */
  77
  78 static kadm5_ret_t
  79 fetch_acl (kadm5_server_context *context,
  80            krb5_const_principal princ,
  81            unsigned *ret_flags)
  82 {
  83     FILE *f;
  84     krb5_error_code ret = 0;
  85     char buf[256];
  86
  87     *ret_flags = 0;
  88
  89     /* no acl file -> no rights */
  90     f = fopen(context->config.acl_file, "r");
  91     if (f == NULL)
  92         return 0;
  93
  94     while(fgets(buf, sizeof(buf), f) != NULL) {
  95         char *foo = NULL, *p;
  96         krb5_principal this_princ;
  97         unsigned flags = 0;
  98
  99         p = strtok_r(buf, " \t\n", &foo);
 100         if(p == NULL)
 101             continue;
 102         if (*p == '#')          /* comment */
 103             continue;
 104         ret = krb5_parse_name(context->context, p, &this_princ);
 105         if(ret)
 106             break;
 107         if(!krb5_principal_compare(context->context,
 108                                    context->caller, this_princ)) {
 109             krb5_free_principal(context->context, this_princ);
 110             continue;
 111         }
 112         krb5_free_principal(context->context, this_princ);
 113         p = strtok_r(NULL, " \t\n", &foo);
 114         if(p == NULL)
 115             continue;
 116         ret = _kadm5_string_to_privs(p, &flags);
 117         if (ret)
 118             break;
 119         p = strtok_r(NULL, " \t\n", &foo);
 120         if (p == NULL) {
 121             *ret_flags = flags;
 122             break;
 123         }
 124         if (princ != NULL) {
 125             krb5_principal pattern_princ;
 126             krb5_boolean match;
 127             const char *c0 = krb5_principal_get_comp_string(context->context,
 128                                                             princ, 0);
 129             const char *pat_c0;
 130
 131             ret = krb5_parse_name(context->context, p, &pattern_princ);
 132             if (ret)
 133                 break;
 134             pat_c0 = krb5_principal_get_comp_string(context->context,
 135                                                     pattern_princ, 0);
 136             match = krb5_principal_match(context->context,
 137                                          princ, pattern_princ);
 138
 139             /*
 140              * If `princ' is a WELLKNOWN name, then require the WELLKNOWN label
 141              * be matched exactly.
 142              *
 143              * FIXME: We could do something similar for krbtgt and kadmin other
 144              *        principal types.
 145              */
 146             if (match && c0 && strcmp(c0, "WELLKNOWN") == 0 &&
 147                 (!pat_c0 || strcmp(pat_c0, "WELLKNOWN") != 0))
 148                 match = FALSE;
 149             krb5_free_principal(context->context, pattern_princ);
 150             if (match) {
 151                 *ret_flags = flags;
 152                 break;
 153             }
 154         }
 155     }
 156     fclose(f);
 157     return ret;
 158 }
 159
 160 krb5_boolean
 161 _kadm5_is_kadmin_service_p(kadm5_server_context *context)
 162 {
 163     krb5_boolean ret;
 164     krb5_principal princ;
 165
 166     if (krb5_parse_name(context->context, KADM5_ADMIN_SERVICE, &princ) != 0)
 167         return FALSE;
 168
 169     ret = krb5_principal_compare(context->context, context->caller, princ);
 170     krb5_free_principal(context->context, princ);
 171
 172     return ret;
 173 }
 174
 175 /*
 176  * set global acl flags in `context' for the current caller.
 177  * return 0 on success or an error
 178  */
 179
 180 kadm5_ret_t
 181 _kadm5_acl_init(kadm5_server_context *context)
 182 {
 183     if (_kadm5_is_kadmin_service_p(context)) {
 184         context->acl_flags = KADM5_PRIV_ALL;
 185         return 0;
 186     }
 187
 188     return fetch_acl (context, NULL, &context->acl_flags);
 189 }
 190
 191 /*
 192  * check if `flags' allows `op'
 193  * return 0 if OK or an error
 194  */
 195
 196 static kadm5_ret_t
 197 check_flags (unsigned op,
 198              unsigned flags)
 199 {
 200     unsigned res = ~flags & op;
 201
 202     if(res & KADM5_PRIV_GET)
 203         return KADM5_AUTH_GET;
 204     if(res & KADM5_PRIV_GET_KEYS)
 205         return KADM5_AUTH_GET_KEYS;
 206     if(res & KADM5_PRIV_ADD)
 207         return KADM5_AUTH_ADD;
 208     if(res & KADM5_PRIV_MODIFY)
 209         return KADM5_AUTH_MODIFY;
 210     if(res & KADM5_PRIV_DELETE)
 211         return KADM5_AUTH_DELETE;
 212     if(res & KADM5_PRIV_CPW)
 213         return KADM5_AUTH_CHANGEPW;
 214     if(res & KADM5_PRIV_LIST)
 215         return KADM5_AUTH_LIST;
 216     if(res)
 217         return KADM5_AUTH_INSUFFICIENT;
 218     return 0;
 219 }
 220
 221 /*
 222  * return 0 if the current caller in `context' is allowed to perform
 223  * `op' on `princ' and otherwise an error
 224  * princ == NULL if it's not relevant.
 225  */
 226
 227 kadm5_ret_t
 228 _kadm5_acl_check_permission(kadm5_server_context *context,
 229                             unsigned op,
 230                             krb5_const_principal princ)
 231 {
 232     kadm5_ret_t ret;
 233     unsigned princ_flags;
 234
 235     ret = check_flags (op, context->acl_flags);
 236     if (ret == 0)
 237         return ret;
 238     ret = fetch_acl (context, princ, &princ_flags);
 239     if (ret)
 240         return ret;
 241     return check_flags (op, princ_flags);
 242 }