source4/rpc_server/drsuapi/writespn.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    implement the DsWriteAccountSpn call
   5
   6    Copyright (C) Stefan Metzmacher 2009
   7    Copyright (C) Andrew Tridgell   2010
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  21 */
  22
  23 #include "includes.h"
  24 #include "rpc_server/dcerpc_server.h"
  25 #include "dsdb/samdb/samdb.h"
  26 #include "dsdb/common/util.h"
  27 #include "system/kerberos.h"
  28 #include "auth/kerberos/kerberos.h"
  29 #include "libcli/security/security.h"
  30 #include "libcli/security/session.h"
  31 #include "rpc_server/drsuapi/dcesrv_drsuapi.h"
  32 #include "auth/session.h"
  33
  34 /*
  35   check that the SPN update should be allowed as an override
  36   via sam_ctx_system
  37
  38   This is only called if the client is not a domain controller or
  39   administrator
  40  */
  41 static bool writespn_check_spn(struct drsuapi_bind_state *b_state,
  42                                struct dcesrv_call_state *dce_call,
  43                                struct ldb_dn *dn,
  44                                const char *spn)
  45 {
  46         /*
  47          * we only allow SPN updates if:
  48          *
  49          * 1) they are on the clients own account object
  50          * 2) they are of the form SERVICE/dnshostname
  51          */
  52         struct dom_sid *user_sid, *sid;
  53         TALLOC_CTX *tmp_ctx = talloc_new(dce_call);
  54         struct ldb_result *res;
  55         const char *attrs[] = { "objectSID", "dNSHostName", NULL };
  56         int ret;
  57         krb5_context krb_ctx;
  58         krb5_error_code kerr;
  59         krb5_principal principal;
  60         krb5_data *component;
  61         const char *dns_name, *dnsHostName;
  62
  63         /* The service principal name shouldn't be NULL */
  64         if (spn == NULL) {
  65                 talloc_free(tmp_ctx);
  66                 return false;
  67         }
  68
  69         /*
  70           get the objectSid of the DN that is being modified, and
  71           check it matches the user_sid in their token
  72          */
  73
  74         ret = dsdb_search_dn(b_state->sam_ctx, tmp_ctx, &res, dn, attrs,
  75                              DSDB_SEARCH_ONE_ONLY);
  76         if (ret != LDB_SUCCESS) {
  77                 talloc_free(tmp_ctx);
  78                 return false;
  79         }
  80
  81         user_sid = &dce_call->conn->auth_state.session_info->security_token->sids[PRIMARY_USER_SID_INDEX];
  82         sid = samdb_result_dom_sid(tmp_ctx, res->msgs[0], "objectSid");
  83         if (sid == NULL) {
  84                 talloc_free(tmp_ctx);
  85                 return false;
  86         }
  87
  88         dnsHostName = ldb_msg_find_attr_as_string(res->msgs[0], "dNSHostName",
  89                                                   NULL);
  90         if (dnsHostName == NULL) {
  91                 talloc_free(tmp_ctx);
  92                 return false;
  93         }
  94
  95         if (!dom_sid_equal(sid, user_sid)) {
  96                 talloc_free(tmp_ctx);
  97                 return false;
  98         }
  99
 100         kerr = smb_krb5_init_context_basic(tmp_ctx,
 101                                            dce_call->conn->dce_ctx->lp_ctx,
 102                                            &krb_ctx);
 103         if (kerr != 0) {
 104                 talloc_free(tmp_ctx);
 105                 return false;
 106         }
 107
 108         ret = krb5_parse_name_flags(krb_ctx, spn, KRB5_PRINCIPAL_PARSE_NO_REALM,
 109                                     &principal);
 110         if (kerr != 0) {
 111                 krb5_free_context(krb_ctx);
 112                 talloc_free(tmp_ctx);
 113                 return false;
 114         }
 115
 116         if (krb5_princ_size(krb_ctx, principal) != 2) {
 117                 krb5_free_principal(krb_ctx, principal);
 118                 krb5_free_context(krb_ctx);
 119                 talloc_free(tmp_ctx);
 120                 return false;
 121         }
 122
 123         component = krb5_princ_component(krb_ctx, principal, 1);
 124         dns_name = (const char *)component->data;
 125
 126         if (strcasecmp(dns_name, dnsHostName) != 0) {
 127                 krb5_free_principal(krb_ctx, principal);
 128                 krb5_free_context(krb_ctx);
 129                 talloc_free(tmp_ctx);
 130                 return false;
 131         }
 132
 133         /* its a simple update on their own account - allow it with
 134          * permissions override */
 135         krb5_free_principal(krb_ctx, principal);
 136         krb5_free_context(krb_ctx);
 137         talloc_free(tmp_ctx);
 138
 139         return true;
 140 }
 141
 142 /*
 143   drsuapi_DsWriteAccountSpn
 144 */
 145 WERROR dcesrv_drsuapi_DsWriteAccountSpn(struct dcesrv_call_state *dce_call, TALLOC_CTX *mem_ctx,
 146                                         struct drsuapi_DsWriteAccountSpn *r)
 147 {
 148         struct drsuapi_bind_state *b_state;
 149         struct dcesrv_handle *h;
 150
 151         *r->out.level_out = r->in.level;
 152
 153         DCESRV_PULL_HANDLE_WERR(h, r->in.bind_handle, DRSUAPI_BIND_HANDLE);
 154         b_state = h->data;
 155
 156         r->out.res = talloc(mem_ctx, union drsuapi_DsWriteAccountSpnResult);
 157         W_ERROR_HAVE_NO_MEMORY(r->out.res);
 158
 159         switch (r->in.level) {
 160                 case 1: {
 161                         struct drsuapi_DsWriteAccountSpnRequest1 *req;
 162                         struct ldb_message *msg;
 163                         uint32_t count;
 164                         unsigned int i;
 165                         int ret;
 166                         unsigned spn_count=0;
 167                         bool passed_checks = true;
 168                         struct ldb_context *sam_ctx;
 169
 170                         req = &r->in.req->req1;
 171                         count = req->count;
 172
 173                         msg = ldb_msg_new(mem_ctx);
 174                         if (msg == NULL) {
 175                                 return WERR_NOMEM;
 176                         }
 177
 178                         msg->dn = ldb_dn_new(msg, b_state->sam_ctx,
 179                                              req->object_dn);
 180                         if ( ! ldb_dn_validate(msg->dn)) {
 181                                 r->out.res->res1.status = WERR_OK;
 182                                 return WERR_OK;
 183                         }
 184
 185                         /* construct mods */
 186                         for (i = 0; i < count; i++) {
 187                                 if (!writespn_check_spn(b_state,
 188                                                        dce_call,
 189                                                        msg->dn,
 190                                                        req->spn_names[i].str)) {
 191                                         passed_checks = false;
 192                                 }
 193                                 ret = ldb_msg_add_string(msg,
 194                                                          "servicePrincipalName",
 195                                                          req->spn_names[i].str);
 196                                 if (ret != LDB_SUCCESS) {
 197                                         return WERR_NOMEM;
 198                                 }
 199                                 spn_count++;
 200                         }
 201
 202                         if (msg->num_elements == 0) {
 203                                 DEBUG(2,("No SPNs need changing on %s\n",
 204                                          ldb_dn_get_linearized(msg->dn)));
 205                                 r->out.res->res1.status = WERR_OK;
 206                                 return WERR_OK;
 207                         }
 208
 209                         for (i=0;i<msg->num_elements;i++) {
 210                                 switch (req->operation) {
 211                                 case DRSUAPI_DS_SPN_OPERATION_ADD:
 212                                         msg->elements[i].flags = LDB_FLAG_MOD_ADD;
 213                                         break;
 214                                 case DRSUAPI_DS_SPN_OPERATION_REPLACE:
 215                                         msg->elements[i].flags = LDB_FLAG_MOD_REPLACE;
 216                                         break;
 217                                 case DRSUAPI_DS_SPN_OPERATION_DELETE:
 218                                         msg->elements[i].flags = LDB_FLAG_MOD_DELETE;
 219                                         break;
 220                                 }
 221                         }
 222
 223                         if (passed_checks && b_state->sam_ctx_system) {
 224                                 sam_ctx = b_state->sam_ctx_system;
 225                         } else {
 226                                 sam_ctx = b_state->sam_ctx;
 227                         }
 228
 229                         /* Apply to database */
 230                         ret = dsdb_modify(sam_ctx, msg, DSDB_MODIFY_PERMISSIVE);
 231                         if (ret != LDB_SUCCESS) {
 232                                 DEBUG(0,("Failed to modify SPNs on %s: %s\n",
 233                                          ldb_dn_get_linearized(msg->dn),
 234                                          ldb_errstring(b_state->sam_ctx)));
 235                                 r->out.res->res1.status = WERR_ACCESS_DENIED;
 236                         } else {
 237                                 DEBUG(2,("Modified %u SPNs on %s\n", spn_count,
 238                                          ldb_dn_get_linearized(msg->dn)));
 239                                 r->out.res->res1.status = WERR_OK;
 240                         }
 241
 242                         return WERR_OK;
 243                 }
 244         }
 245
 246         return WERR_UNKNOWN_LEVEL;
 247 }