auth/kerberos/gssapi_pac.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    kerberos authorization data (PAC) utility library
   4    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2011
   5    Copyright (C) Simo Sorce 2010.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include "includes.h"
  22 #ifdef HAVE_KRB5
  23
  24 #include "auth/kerberos/pac_utils.h"
  25
  26 #if 0
  27 /* FIXME - need proper configure/waf test
  28  * to determine if gss_mech_krb5 and friends
  29  * exist. JRA.
  30  */
  31 /*
  32  * These are not exported by Solaris -lkrb5
  33  * Maybe move to libreplace somewhere?
  34  */
  35 static const gss_OID_desc krb5_gss_oid_array[] = {
  36         /* this is the official, rfc-specified OID */
  37         { 9, "\052\206\110\206\367\022\001\002\002" },
  38         /* this is the pre-RFC mech OID */
  39         { 5, "\053\005\001\005\002" },
  40         /* this is the unofficial, incorrect mech OID emitted by MS */
  41         { 9, "\052\206\110\202\367\022\001\002\002" },
  42         { 0, 0 }
  43 };
  44
  45 const gss_OID_desc * const gss_mech_krb5              = krb5_gss_oid_array+0;
  46 const gss_OID_desc * const gss_mech_krb5_old          = krb5_gss_oid_array+1;
  47 const gss_OID_desc * const gss_mech_krb5_wrong        = krb5_gss_oid_array+2;
  48 #endif
  49
  50 #ifndef GSS_KRB5_INQ_SSPI_SESSION_KEY_OID
  51 #define GSS_KRB5_INQ_SSPI_SESSION_KEY_OID_LENGTH 11
  52 #define GSS_KRB5_INQ_SSPI_SESSION_KEY_OID "\x2a\x86\x48\x86\xf7\x12\x01\x02\x02\x05\x05"
  53 #endif
  54
  55 gss_OID_desc gse_sesskey_inq_oid = {
  56         GSS_KRB5_INQ_SSPI_SESSION_KEY_OID_LENGTH,
  57         (void *)GSS_KRB5_INQ_SSPI_SESSION_KEY_OID
  58 };
  59
  60 #ifndef GSS_KRB5_SESSION_KEY_ENCTYPE_OID
  61 #define GSS_KRB5_SESSION_KEY_ENCTYPE_OID_LENGTH 10
  62 #define GSS_KRB5_SESSION_KEY_ENCTYPE_OID  "\x2a\x86\x48\x86\xf7\x12\x01\x02\x02\x04"
  63 #endif
  64
  65 gss_OID_desc gse_sesskeytype_oid = {
  66         GSS_KRB5_SESSION_KEY_ENCTYPE_OID_LENGTH,
  67         (void *)GSS_KRB5_SESSION_KEY_ENCTYPE_OID
  68 };
  69
  70 /* The Heimdal OID for getting the PAC */
  71 #define EXTRACT_PAC_AUTHZ_DATA_FROM_SEC_CONTEXT_OID_LENGTH 8
  72 /*                                                      EXTRACTION OID             AUTHZ ID */
  73 #define EXTRACT_PAC_AUTHZ_DATA_FROM_SEC_CONTEXT_OID "\x2a\x85\x70\x2b\x0d\x03" "\x81\x00"
  74
  75 NTSTATUS gssapi_obtain_pac_blob(TALLOC_CTX *mem_ctx,
  76                                 gss_ctx_id_t gssapi_context,
  77                                 gss_name_t gss_client_name,
  78                                 DATA_BLOB *pac_blob)
  79 {
  80         NTSTATUS status;
  81         OM_uint32 gss_maj, gss_min;
  82 #ifdef HAVE_GSS_GET_NAME_ATTRIBUTE
  83         gss_buffer_desc pac_buffer;
  84         gss_buffer_desc pac_display_buffer;
  85         gss_buffer_desc pac_name = {
  86                 .value = discard_const("urn:mspac:"),
  87                 .length = sizeof("urn:mspac:")-1
  88         };
  89         int more = -1;
  90         int authenticated = false;
  91         int complete = false;
  92
  93         gss_maj = gss_get_name_attribute(
  94                 &gss_min, gss_client_name, &pac_name,
  95                 &authenticated, &complete,
  96                 &pac_buffer, &pac_display_buffer, &more);
  97
  98         if (gss_maj != 0) {
  99                 DEBUG(0, ("obtaining PAC via GSSAPI gss_get_name_attribute failed: %s\n",
 100                           gssapi_error_string(mem_ctx, gss_maj, gss_min, gss_mech_krb5)));
 101                 return NT_STATUS_ACCESS_DENIED;
 102         } else if (authenticated && complete) {
 103                 /* The PAC blob is returned directly */
 104                 *pac_blob = data_blob_talloc(mem_ctx, pac_buffer.value,
 105                                             pac_buffer.length);
 106
 107                 if (!pac_blob->data) {
 108                         status = NT_STATUS_NO_MEMORY;
 109                 } else {
 110                         status = NT_STATUS_OK;
 111                 }
 112
 113                 gss_maj = gss_release_buffer(&gss_min, &pac_buffer);
 114                 gss_maj = gss_release_buffer(&gss_min, &pac_display_buffer);
 115                 return status;
 116         } else {
 117                 DEBUG(0, ("obtaining PAC via GSSAPI failed: authenticated: %s, complete: %s, more: %s\n",
 118                           authenticated ? "true" : "false",
 119                           complete ? "true" : "false",
 120                           more ? "true" : "false"));
 121                 return NT_STATUS_ACCESS_DENIED;
 122         }
 123
 124 #elif defined(HAVE_GSS_INQUIRE_SEC_CONTEXT_BY_OID)
 125         gss_OID_desc pac_data_oid = {
 126                 .elements = discard_const(EXTRACT_PAC_AUTHZ_DATA_FROM_SEC_CONTEXT_OID),
 127                 .length = EXTRACT_PAC_AUTHZ_DATA_FROM_SEC_CONTEXT_OID_LENGTH
 128         };
 129
 130         gss_buffer_set_t set = GSS_C_NO_BUFFER_SET;
 131
 132         /* If we didn't have the routine to get a verified, validated
 133          * PAC (supplied only by MIT at the time of writing), then try
 134          * with the Heimdal OID (fetches the PAC directly and always
 135          * validates) */
 136         gss_maj = gss_inquire_sec_context_by_oid(
 137                                 &gss_min, gssapi_context,
 138                                 &pac_data_oid, &set);
 139
 140         /* First check for the error MIT gives for an unknown OID */
 141         if (gss_maj == GSS_S_UNAVAILABLE) {
 142                 DEBUG(1, ("unable to obtain a PAC against this GSSAPI library.  "
 143                           "GSSAPI secured connections are available only with Heimdal or MIT Kerberos >= 1.8\n"));
 144         } else if (gss_maj != 0) {
 145                 DEBUG(2, ("obtaining PAC via GSSAPI gss_inqiure_sec_context_by_oid (Heimdal OID) failed: %s\n",
 146                           gssapi_error_string(mem_ctx, gss_maj, gss_min, gss_mech_krb5)));
 147         } else {
 148                 if (set == GSS_C_NO_BUFFER_SET) {
 149                         DEBUG(0, ("gss_inquire_sec_context_by_oid returned unknown "
 150                                   "data in results.\n"));
 151                         return NT_STATUS_INTERNAL_ERROR;
 152                 }
 153
 154                 /* The PAC blob is returned directly */
 155                 *pac_blob = data_blob_talloc(mem_ctx, set->elements[0].value,
 156                                             set->elements[0].length);
 157                 if (!pac_blob->data) {
 158                         status = NT_STATUS_NO_MEMORY;
 159                 } else {
 160                         status = NT_STATUS_OK;
 161                 }
 162
 163                 gss_maj = gss_release_buffer_set(&gss_min, &set);
 164                 return status;
 165         }
 166 #else
 167         DEBUG(1, ("unable to obtain a PAC against this GSSAPI library.  "
 168                   "GSSAPI secured connections are available only with Heimdal or MIT Kerberos >= 1.8\n"));
 169 #endif
 170         return NT_STATUS_ACCESS_DENIED;
 171 }
 172
 173 NTSTATUS gssapi_get_session_key(TALLOC_CTX *mem_ctx,
 174                                 gss_ctx_id_t gssapi_context,
 175                                 DATA_BLOB *session_key,
 176                                 uint32_t *keytype)
 177 {
 178         OM_uint32 gss_min, gss_maj;
 179         gss_buffer_set_t set = GSS_C_NO_BUFFER_SET;
 180
 181         gss_maj = gss_inquire_sec_context_by_oid(
 182                                 &gss_min, gssapi_context,
 183                                 &gse_sesskey_inq_oid, &set);
 184         if (gss_maj) {
 185                 DEBUG(0, ("gss_inquire_sec_context_by_oid failed [%s]\n",
 186                           gssapi_error_string(mem_ctx, gss_maj, gss_min, gss_mech_krb5)));
 187                 return NT_STATUS_NO_USER_SESSION_KEY;
 188         }
 189
 190         if ((set == GSS_C_NO_BUFFER_SET) ||
 191             (set->count == 0)) {
 192 #ifdef HAVE_GSSKRB5_GET_SUBKEY
 193                 krb5_keyblock *subkey;
 194                 gss_maj = gsskrb5_get_subkey(&gss_min,
 195                                              gssapi_context,
 196                                              &subkey);
 197                 if (gss_maj != 0) {
 198                         DEBUG(1, ("NO session key for this mech\n"));
 199                         return NT_STATUS_NO_USER_SESSION_KEY;
 200                 }
 201                 if (session_key) {
 202                         *session_key = data_blob_talloc(mem_ctx,
 203                                                         KRB5_KEY_DATA(subkey), KRB5_KEY_LENGTH(subkey));
 204                 }
 205                 if (keytype) {
 206                         *keytype = KRB5_KEY_TYPE(subkey);
 207                 }
 208                 krb5_free_keyblock(NULL /* should be krb5_context */, subkey);
 209                 return NT_STATUS_OK;
 210 #else
 211                 DEBUG(0, ("gss_inquire_sec_context_by_oid didn't return any session key (and no alternative method available)\n"));
 212                 return NT_STATUS_NO_USER_SESSION_KEY;
 213 #endif
 214         }
 215
 216         if (session_key) {
 217                 *session_key = data_blob_talloc(mem_ctx, set->elements[0].value,
 218                                                 set->elements[0].length);
 219         }
 220
 221         if (keytype) {
 222                 int diflen, i;
 223                 const char *p;
 224
 225                 if (set->count < 2) {
 226
 227 #ifdef HAVE_GSSKRB5_GET_SUBKEY
 228                         krb5_keyblock *subkey;
 229                         gss_maj = gsskrb5_get_subkey(&gss_min,
 230                                                      gssapi_context,
 231                                                      &subkey);
 232                         if (gss_maj == 0) {
 233                                 *keytype = KRB5_KEY_TYPE(subkey);
 234                                 krb5_free_keyblock(NULL /* should be krb5_context */, subkey);
 235                         } else
 236 #else
 237                         {
 238                                 *keytype = 0;
 239                         }
 240 #endif
 241                         gss_maj = gss_release_buffer_set(&gss_min, &set);
 242
 243                         return NT_STATUS_OK;
 244
 245                 } else if (memcmp(set->elements[1].value,
 246                                   gse_sesskeytype_oid.elements,
 247                                   gse_sesskeytype_oid.length) != 0) {
 248                         /* Perhaps a non-krb5 session key */
 249                         *keytype = 0;
 250                         gss_maj = gss_release_buffer_set(&gss_min, &set);
 251                         return NT_STATUS_OK;
 252                 }
 253                 p = set->elements[1].value + gse_sesskeytype_oid.length;
 254                 diflen = set->elements[1].length - gse_sesskeytype_oid.length;
 255                 if (diflen <= 0) {
 256                         gss_maj = gss_release_buffer_set(&gss_min, &set);
 257                         return NT_STATUS_INVALID_PARAMETER;
 258                 }
 259                 *keytype = 0;
 260                 for (i = 0; i < diflen; i++) {
 261                         *keytype = (*keytype << 7) | (p[i] & 0x7f);
 262                         if (i + 1 != diflen && (p[i] & 0x80) == 0) {
 263                                 gss_maj = gss_release_buffer_set(&gss_min, &set);
 264                                 return NT_STATUS_INVALID_PARAMETER;
 265                         }
 266                 }
 267         }
 268
 269         gss_maj = gss_release_buffer_set(&gss_min, &set);
 270         return NT_STATUS_OK;
 271 }
 272
 273
 274 char *gssapi_error_string(TALLOC_CTX *mem_ctx,
 275                           OM_uint32 maj_stat, OM_uint32 min_stat,
 276                           const gss_OID mech)
 277 {
 278         OM_uint32 disp_min_stat, disp_maj_stat;
 279         gss_buffer_desc maj_error_message;
 280         gss_buffer_desc min_error_message;
 281         char *maj_error_string, *min_error_string;
 282         OM_uint32 msg_ctx = 0;
 283
 284         char *ret;
 285
 286         maj_error_message.value = NULL;
 287         min_error_message.value = NULL;
 288         maj_error_message.length = 0;
 289         min_error_message.length = 0;
 290
 291         disp_maj_stat = gss_display_status(&disp_min_stat, maj_stat,
 292                                            GSS_C_GSS_CODE, mech,
 293                                            &msg_ctx, &maj_error_message);
 294         disp_maj_stat = gss_display_status(&disp_min_stat, min_stat,
 295                                            GSS_C_MECH_CODE, mech,
 296                                            &msg_ctx, &min_error_message);
 297
 298         maj_error_string = talloc_strndup(mem_ctx,
 299                                           (char *)maj_error_message.value,
 300                                           maj_error_message.length);
 301
 302         min_error_string = talloc_strndup(mem_ctx,
 303                                           (char *)min_error_message.value,
 304                                           min_error_message.length);
 305
 306         ret = talloc_asprintf(mem_ctx, "%s: %s",
 307                                 maj_error_string, min_error_string);
 308
 309         talloc_free(maj_error_string);
 310         talloc_free(min_error_string);
 311
 312         gss_release_buffer(&disp_min_stat, &maj_error_message);
 313         gss_release_buffer(&disp_min_stat, &min_error_message);
 314
 315         return ret;
 316 }
 317
 318 #endif /* HAVE_KRB5 */