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 "lib/krb5_wrap/krb5_samba.h"
  25 #include "auth/kerberos/pac_utils.h"
  26
  27 #if 0
  28 /* FIXME - need proper configure/waf test
  29  * to determine if gss_mech_krb5 and friends
  30  * exist. JRA.
  31  */
  32 /*
  33  * These are not exported by Solaris -lkrb5
  34  * Maybe move to libreplace somewhere?
  35  */
  36 static const gss_OID_desc krb5_gss_oid_array[] = {
  37         /* this is the official, rfc-specified OID */
  38         { 9, "\052\206\110\206\367\022\001\002\002" },
  39         /* this is the pre-RFC mech OID */
  40         { 5, "\053\005\001\005\002" },
  41         /* this is the unofficial, incorrect mech OID emitted by MS */
  42         { 9, "\052\206\110\202\367\022\001\002\002" },
  43         { 0, 0 }
  44 };
  45
  46 const gss_OID_desc * const gss_mech_krb5              = krb5_gss_oid_array+0;
  47 const gss_OID_desc * const gss_mech_krb5_old          = krb5_gss_oid_array+1;
  48 const gss_OID_desc * const gss_mech_krb5_wrong        = krb5_gss_oid_array+2;
  49 #endif
  50
  51 #ifndef GSS_KRB5_INQ_SSPI_SESSION_KEY_OID
  52 #define GSS_KRB5_INQ_SSPI_SESSION_KEY_OID_LENGTH 11
  53 #define GSS_KRB5_INQ_SSPI_SESSION_KEY_OID "\x2a\x86\x48\x86\xf7\x12\x01\x02\x02\x05\x05"
  54 #endif
  55
  56 gss_OID_desc gse_sesskey_inq_oid = {
  57         GSS_KRB5_INQ_SSPI_SESSION_KEY_OID_LENGTH,
  58         (void *)GSS_KRB5_INQ_SSPI_SESSION_KEY_OID
  59 };
  60
  61 #ifndef GSS_KRB5_SESSION_KEY_ENCTYPE_OID
  62 #define GSS_KRB5_SESSION_KEY_ENCTYPE_OID_LENGTH 10
  63 #define GSS_KRB5_SESSION_KEY_ENCTYPE_OID  "\x2a\x86\x48\x86\xf7\x12\x01\x02\x02\x04"
  64 #endif
  65
  66 gss_OID_desc gse_sesskeytype_oid = {
  67         GSS_KRB5_SESSION_KEY_ENCTYPE_OID_LENGTH,
  68         (void *)GSS_KRB5_SESSION_KEY_ENCTYPE_OID
  69 };
  70
  71 /* The Heimdal OID for getting the PAC */
  72 #define EXTRACT_PAC_AUTHZ_DATA_FROM_SEC_CONTEXT_OID_LENGTH 8
  73 /*                                                      EXTRACTION OID             AUTHZ ID */
  74 #define EXTRACT_PAC_AUTHZ_DATA_FROM_SEC_CONTEXT_OID "\x2a\x85\x70\x2b\x0d\x03" "\x81\x00"
  75
  76 NTSTATUS gssapi_obtain_pac_blob(TALLOC_CTX *mem_ctx,
  77                                 gss_ctx_id_t gssapi_context,
  78                                 gss_name_t gss_client_name,
  79                                 DATA_BLOB *pac_blob)
  80 {
  81         NTSTATUS status;
  82         OM_uint32 gss_maj, gss_min;
  83 #ifdef HAVE_GSS_GET_NAME_ATTRIBUTE
  84         gss_buffer_desc pac_buffer;
  85         gss_buffer_desc pac_display_buffer;
  86         gss_buffer_desc pac_name = {
  87                 .value = discard_const("urn:mspac:"),
  88                 .length = sizeof("urn:mspac:")-1
  89         };
  90         int more = -1;
  91         int authenticated = false;
  92         int complete = false;
  93
  94         gss_maj = gss_get_name_attribute(
  95                 &gss_min, gss_client_name, &pac_name,
  96                 &authenticated, &complete,
  97                 &pac_buffer, &pac_display_buffer, &more);
  98
  99         if (gss_maj != 0) {
 100                 DEBUG(0, ("obtaining PAC via GSSAPI gss_get_name_attribute failed: %s\n",
 101                           gssapi_error_string(mem_ctx, gss_maj, gss_min, gss_mech_krb5)));
 102                 return NT_STATUS_ACCESS_DENIED;
 103         } else if (authenticated && complete) {
 104                 /* The PAC blob is returned directly */
 105                 *pac_blob = data_blob_talloc(mem_ctx, pac_buffer.value,
 106                                             pac_buffer.length);
 107
 108                 if (!pac_blob->data) {
 109                         status = NT_STATUS_NO_MEMORY;
 110                 } else {
 111                         status = NT_STATUS_OK;
 112                 }
 113
 114                 gss_maj = gss_release_buffer(&gss_min, &pac_buffer);
 115                 gss_maj = gss_release_buffer(&gss_min, &pac_display_buffer);
 116                 return status;
 117         } else {
 118                 DEBUG(0, ("obtaining PAC via GSSAPI failed: authenticated: %s, complete: %s, more: %s\n",
 119                           authenticated ? "true" : "false",
 120                           complete ? "true" : "false",
 121                           more ? "true" : "false"));
 122                 return NT_STATUS_ACCESS_DENIED;
 123         }
 124
 125 #elif defined(HAVE_GSS_INQUIRE_SEC_CONTEXT_BY_OID)
 126         gss_OID_desc pac_data_oid = {
 127                 .elements = discard_const(EXTRACT_PAC_AUTHZ_DATA_FROM_SEC_CONTEXT_OID),
 128                 .length = EXTRACT_PAC_AUTHZ_DATA_FROM_SEC_CONTEXT_OID_LENGTH
 129         };
 130
 131         gss_buffer_set_t set = GSS_C_NO_BUFFER_SET;
 132
 133         /* If we didn't have the routine to get a verified, validated
 134          * PAC (supplied only by MIT at the time of writing), then try
 135          * with the Heimdal OID (fetches the PAC directly and always
 136          * validates) */
 137         gss_maj = gss_inquire_sec_context_by_oid(
 138                                 &gss_min, gssapi_context,
 139                                 &pac_data_oid, &set);
 140
 141         /* First check for the error MIT gives for an unknown OID */
 142         if (gss_maj == GSS_S_UNAVAILABLE) {
 143                 DEBUG(1, ("unable to obtain a PAC against this GSSAPI library.  "
 144                           "GSSAPI secured connections are available only with Heimdal or MIT Kerberos >= 1.8\n"));
 145         } else if (gss_maj != 0) {
 146                 DEBUG(2, ("obtaining PAC via GSSAPI gss_inqiure_sec_context_by_oid (Heimdal OID) failed: %s\n",
 147                           gssapi_error_string(mem_ctx, gss_maj, gss_min, gss_mech_krb5)));
 148         } else {
 149                 if (set == GSS_C_NO_BUFFER_SET) {
 150                         DEBUG(0, ("gss_inquire_sec_context_by_oid returned unknown "
 151                                   "data in results.\n"));
 152                         return NT_STATUS_INTERNAL_ERROR;
 153                 }
 154
 155                 /* The PAC blob is returned directly */
 156                 *pac_blob = data_blob_talloc(mem_ctx, set->elements[0].value,
 157                                             set->elements[0].length);
 158                 if (!pac_blob->data) {
 159                         status = NT_STATUS_NO_MEMORY;
 160                 } else {
 161                         status = NT_STATUS_OK;
 162                 }
 163
 164                 gss_maj = gss_release_buffer_set(&gss_min, &set);
 165                 return status;
 166         }
 167 #else
 168         DEBUG(1, ("unable to obtain a PAC against this GSSAPI library.  "
 169                   "GSSAPI secured connections are available only with Heimdal or MIT Kerberos >= 1.8\n"));
 170 #endif
 171         return NT_STATUS_ACCESS_DENIED;
 172 }
 173
 174 NTSTATUS gssapi_get_session_key(TALLOC_CTX *mem_ctx,
 175                                 gss_ctx_id_t gssapi_context,
 176                                 DATA_BLOB *session_key,
 177                                 uint32_t *keytype)
 178 {
 179         OM_uint32 gss_min, gss_maj;
 180         gss_buffer_set_t set = GSS_C_NO_BUFFER_SET;
 181
 182         gss_maj = gss_inquire_sec_context_by_oid(
 183                                 &gss_min, gssapi_context,
 184                                 &gse_sesskey_inq_oid, &set);
 185         if (gss_maj) {
 186                 DEBUG(0, ("gss_inquire_sec_context_by_oid failed [%s]\n",
 187                           gssapi_error_string(mem_ctx, gss_maj, gss_min, gss_mech_krb5)));
 188                 return NT_STATUS_NO_USER_SESSION_KEY;
 189         }
 190
 191         if ((set == GSS_C_NO_BUFFER_SET) ||
 192             (set->count == 0)) {
 193 #ifdef HAVE_GSSKRB5_GET_SUBKEY
 194                 krb5_keyblock *subkey;
 195                 gss_maj = gsskrb5_get_subkey(&gss_min,
 196                                              gssapi_context,
 197                                              &subkey);
 198                 if (gss_maj != 0) {
 199                         DEBUG(1, ("NO session key for this mech\n"));
 200                         return NT_STATUS_NO_USER_SESSION_KEY;
 201                 }
 202                 if (session_key) {
 203                         *session_key = data_blob_talloc(mem_ctx,
 204                                                         KRB5_KEY_DATA(subkey), KRB5_KEY_LENGTH(subkey));
 205                 }
 206                 if (keytype) {
 207                         *keytype = KRB5_KEY_TYPE(subkey);
 208                 }
 209                 krb5_free_keyblock(NULL /* should be krb5_context */, subkey);
 210                 return NT_STATUS_OK;
 211 #else
 212                 DEBUG(0, ("gss_inquire_sec_context_by_oid didn't return any session key (and no alternative method available)\n"));
 213                 return NT_STATUS_NO_USER_SESSION_KEY;
 214 #endif
 215         }
 216
 217         if (session_key) {
 218                 *session_key = data_blob_talloc(mem_ctx, set->elements[0].value,
 219                                                 set->elements[0].length);
 220         }
 221
 222         if (keytype) {
 223                 int diflen, i;
 224                 const char *p;
 225
 226                 if (set->count < 2) {
 227
 228 #ifdef HAVE_GSSKRB5_GET_SUBKEY
 229                         krb5_keyblock *subkey;
 230                         gss_maj = gsskrb5_get_subkey(&gss_min,
 231                                                      gssapi_context,
 232                                                      &subkey);
 233                         if (gss_maj == 0) {
 234                                 *keytype = KRB5_KEY_TYPE(subkey);
 235                                 krb5_free_keyblock(NULL /* should be krb5_context */, subkey);
 236                         } else
 237 #else
 238                         {
 239                                 *keytype = 0;
 240                         }
 241 #endif
 242                         gss_maj = gss_release_buffer_set(&gss_min, &set);
 243
 244                         return NT_STATUS_OK;
 245
 246                 } else if (memcmp(set->elements[1].value,
 247                                   gse_sesskeytype_oid.elements,
 248                                   gse_sesskeytype_oid.length) != 0) {
 249                         /* Perhaps a non-krb5 session key */
 250                         *keytype = 0;
 251                         gss_maj = gss_release_buffer_set(&gss_min, &set);
 252                         return NT_STATUS_OK;
 253                 }
 254                 p = set->elements[1].value + gse_sesskeytype_oid.length;
 255                 diflen = set->elements[1].length - gse_sesskeytype_oid.length;
 256                 if (diflen <= 0) {
 257                         gss_maj = gss_release_buffer_set(&gss_min, &set);
 258                         return NT_STATUS_INVALID_PARAMETER;
 259                 }
 260                 *keytype = 0;
 261                 for (i = 0; i < diflen; i++) {
 262                         *keytype = (*keytype << 7) | (p[i] & 0x7f);
 263                         if (i + 1 != diflen && (p[i] & 0x80) == 0) {
 264                                 gss_maj = gss_release_buffer_set(&gss_min, &set);
 265                                 return NT_STATUS_INVALID_PARAMETER;
 266                         }
 267                 }
 268         }
 269
 270         gss_maj = gss_release_buffer_set(&gss_min, &set);
 271         return NT_STATUS_OK;
 272 }
 273
 274
 275 char *gssapi_error_string(TALLOC_CTX *mem_ctx,
 276                           OM_uint32 maj_stat, OM_uint32 min_stat,
 277                           const gss_OID mech)
 278 {
 279         OM_uint32 disp_min_stat, disp_maj_stat;
 280         gss_buffer_desc maj_error_message;
 281         gss_buffer_desc min_error_message;
 282         char *maj_error_string, *min_error_string;
 283         OM_uint32 msg_ctx = 0;
 284
 285         char *ret;
 286
 287         maj_error_message.value = NULL;
 288         min_error_message.value = NULL;
 289         maj_error_message.length = 0;
 290         min_error_message.length = 0;
 291
 292         disp_maj_stat = gss_display_status(&disp_min_stat, maj_stat,
 293                                            GSS_C_GSS_CODE, mech,
 294                                            &msg_ctx, &maj_error_message);
 295         disp_maj_stat = gss_display_status(&disp_min_stat, min_stat,
 296                                            GSS_C_MECH_CODE, mech,
 297                                            &msg_ctx, &min_error_message);
 298
 299         maj_error_string = talloc_strndup(mem_ctx,
 300                                           (char *)maj_error_message.value,
 301                                           maj_error_message.length);
 302
 303         min_error_string = talloc_strndup(mem_ctx,
 304                                           (char *)min_error_message.value,
 305                                           min_error_message.length);
 306
 307         ret = talloc_asprintf(mem_ctx, "%s: %s",
 308                                 maj_error_string, min_error_string);
 309
 310         talloc_free(maj_error_string);
 311         talloc_free(min_error_string);
 312
 313         gss_release_buffer(&disp_min_stat, &maj_error_message);
 314         gss_release_buffer(&disp_min_stat, &min_error_message);
 315
 316         return ret;
 317 }
 318
 319 #endif /* HAVE_KRB5 */