src/core/sip-sec-krb5.c

   1 /**
   2  * @file sip-sec-krb5.c
   3  *
   4  * pidgin-sipe
   5  *
   6  * Copyright (C) 2010-2013 SIPE Project <http://sipe.sourceforge.net/>
   7  * Copyright (C) 2009 pier11 <pier11@operamail.com>
   8  *
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  23  */
  24
  25 #include <glib.h>
  26 #include <string.h>
  27 #include <gssapi/gssapi.h>
  28 #include <gssapi/gssapi_krb5.h>
  29 #include <krb5.h>
  30
  31 #include "sipe-common.h"
  32 #include "sip-sec.h"
  33 #include "sip-sec-mech.h"
  34 #include "sip-sec-krb5.h"
  35 #include "sipe-backend.h"
  36
  37 /* Security context for Kerberos */
  38 typedef struct _context_krb5 {
  39         struct sip_sec_context common;
  40         gss_cred_id_t cred_krb5;
  41         gss_ctx_id_t ctx_krb5;
  42         const gchar *domain;
  43         const gchar *username;
  44         const gchar *password;
  45 } *context_krb5;
  46
  47 #define SIP_SEC_FLAG_KRB5_RETRY_AUTH 0x00010000
  48
  49 static void sip_sec_krb5_print_gss_error(char *func, OM_uint32 ret, OM_uint32 minor);
  50
  51 static gboolean sip_sec_krb5_obtain_tgt(context_krb5 context);
  52
  53 static void sip_sec_krb5_destroy_context(context_krb5 context)
  54 {
  55         OM_uint32 ret;
  56         OM_uint32 minor;
  57
  58         if (context->ctx_krb5 != GSS_C_NO_CONTEXT) {
  59                 ret = gss_delete_sec_context(&minor, &(context->ctx_krb5), GSS_C_NO_BUFFER);
  60                 if (GSS_ERROR(ret)) {
  61                         sip_sec_krb5_print_gss_error("gss_delete_sec_context", ret, minor);
  62                         SIPE_DEBUG_ERROR("sip_sec_krb5_destroy_context: failed to delete security context (ret=%d)", (int)ret);
  63                 }
  64                 context->ctx_krb5 = GSS_C_NO_CONTEXT;
  65         }
  66
  67         if (context->cred_krb5) {
  68                 ret = gss_release_cred(&minor, &(context->cred_krb5));
  69                 if (GSS_ERROR(ret)) {
  70                         sip_sec_krb5_print_gss_error("gss_release_cred", ret, minor);
  71                         SIPE_DEBUG_ERROR("sip_sec_krb5_destroy_context: failed to release credentials (ret=%d)", (int)ret);
  72                 }
  73                 context->cred_krb5 = NULL;
  74         }
  75 }
  76
  77 static gboolean sip_sec_krb5_acquire_credentials(context_krb5 context)
  78 {
  79         OM_uint32 ret;
  80         OM_uint32 minor;
  81         gss_cred_id_t credentials;
  82
  83         /* Acquire default user credentials */
  84         ret = gss_acquire_cred(&minor,
  85                                GSS_C_NO_NAME,
  86                                GSS_C_INDEFINITE,
  87                                GSS_C_NO_OID_SET,
  88                                GSS_C_INITIATE,
  89                                &credentials,
  90                                NULL,
  91                                NULL);
  92
  93         if (GSS_ERROR(ret)) {
  94                 sip_sec_krb5_print_gss_error("gss_acquire_cred", ret, minor);
  95                 SIPE_DEBUG_ERROR("sip_sec_krb5_acquire_credentials: failed to acquire credentials (ret=%d)", (int)ret);
  96                 return(FALSE);
  97         } else {
  98                 context->cred_krb5 = credentials;
  99                 return(TRUE);
 100         }
 101 }
 102
 103 static gboolean sip_sec_krb5_initialize_context(context_krb5 context,
 104                                                 SipSecBuffer in_buff,
 105                                                 SipSecBuffer *out_buff,
 106                                                 const gchar *service_name)
 107 {
 108         OM_uint32 ret;
 109         OM_uint32 minor, minor_ignore;
 110         OM_uint32 expiry;
 111         gss_buffer_desc input_token;
 112         gss_buffer_desc output_token;
 113         gss_buffer_desc input_name_buffer;
 114         gss_name_t target_name;
 115
 116         input_name_buffer.value  = (void *) service_name;
 117         input_name_buffer.length = strlen(service_name) + 1;
 118
 119         ret = gss_import_name(&minor,
 120                               &input_name_buffer,
 121                               (gss_OID) GSS_KRB5_NT_PRINCIPAL_NAME,
 122                               &target_name);
 123         if (GSS_ERROR(ret)) {
 124                 sip_sec_krb5_print_gss_error("gss_import_name", ret, minor);
 125                 SIPE_DEBUG_ERROR("sip_sec_krb5_initialize_context: failed to construct target name (ret=%d)", (int)ret);
 126                 return(FALSE);
 127         }
 128
 129         input_token.length = in_buff.length;
 130         input_token.value = in_buff.value;
 131
 132         output_token.length = 0;
 133         output_token.value = NULL;
 134
 135         ret = gss_init_sec_context(&minor,
 136                                    context->cred_krb5,
 137                                    &(context->ctx_krb5),
 138                                    target_name,
 139                                    GSS_C_NO_OID,
 140                                    GSS_C_INTEG_FLAG,
 141                                    GSS_C_INDEFINITE,
 142                                    GSS_C_NO_CHANNEL_BINDINGS,
 143                                    &input_token,
 144                                    NULL,
 145                                    &output_token,
 146                                    NULL,
 147                                    &expiry);
 148         gss_release_name(&minor_ignore, &target_name);
 149
 150         if (GSS_ERROR(ret)) {
 151                 gss_release_buffer(&minor_ignore, &output_token);
 152                 sip_sec_krb5_print_gss_error("gss_init_sec_context", ret, minor);
 153                 SIPE_DEBUG_ERROR("sip_sec_krb5_initialize_context: failed to initialize context (ret=%d)", (int)ret);
 154                 return(FALSE);
 155         }
 156
 157         out_buff->length = output_token.length;
 158         out_buff->value  = g_memdup(output_token.value, output_token.length);
 159         gss_release_buffer(&minor_ignore, &output_token);
 160
 161         context->common.expires = (int)expiry;
 162
 163         /* Authentication is completed */
 164         context->common.flags |= SIP_SEC_FLAG_COMMON_READY;
 165
 166         return(TRUE);
 167 }
 168
 169 /* sip-sec-mech.h API implementation for Kerberos/GSS-API */
 170
 171 static gboolean
 172 sip_sec_acquire_cred__krb5(SipSecContext context,
 173                            const gchar *domain,
 174                            const gchar *username,
 175                            const gchar *password)
 176 {
 177         context_krb5 ctx = (context_krb5) context;
 178
 179         SIPE_DEBUG_INFO_NOFORMAT("sip_sec_acquire_cred__krb5: started");
 180
 181         /* remember authentication information */
 182         ctx->domain     = domain ? domain : "";
 183         ctx->username   = username;
 184         ctx->password   = password;
 185
 186         /*
 187          * This will be TRUE for SIP, which is the first time when we'll try
 188          * to authenticate with Kerberos. We'll allow one retry with the
 189          * authentication information provided by the user (see above).
 190          *
 191          * This will be FALSE for HTTP connections. If Kerberos authentication
 192          * succeeded for SIP already, then there is no need to retry.
 193          */
 194         if ((context->flags & SIP_SEC_FLAG_COMMON_HTTP) == 0)
 195                 context->flags |= SIP_SEC_FLAG_KRB5_RETRY_AUTH;
 196
 197         return(sip_sec_krb5_acquire_credentials(ctx));
 198 }
 199
 200 static gboolean
 201 sip_sec_init_sec_context__krb5(SipSecContext context,
 202                                SipSecBuffer in_buff,
 203                                SipSecBuffer *out_buff,
 204                                const gchar *service_name)
 205 {
 206         OM_uint32 ret;
 207         OM_uint32 minor;
 208         context_krb5 ctx = (context_krb5) context;
 209         gboolean result;
 210
 211         SIPE_DEBUG_INFO_NOFORMAT("sip_sec_init_sec_context__krb5: started");
 212
 213         /* Delete old context first */
 214         if (ctx->ctx_krb5 != GSS_C_NO_CONTEXT) {
 215                 ret = gss_delete_sec_context(&minor,
 216                                              &(ctx->ctx_krb5),
 217                                              GSS_C_NO_BUFFER);
 218                 if (GSS_ERROR(ret)) {
 219                         sip_sec_krb5_print_gss_error("gss_delete_sec_context", ret, minor);
 220                         SIPE_DEBUG_ERROR("sip_sec_init_sec_context__krb5: failed to delete security context (ret=%d)", (int)ret);
 221                 }
 222                 ctx->ctx_krb5 = GSS_C_NO_CONTEXT;
 223         }
 224
 225         result = sip_sec_krb5_initialize_context(ctx,
 226                                                  in_buff,
 227                                                  out_buff,
 228                                                  service_name);
 229
 230         /*
 231          * If context initialization fails retry after trying to obtaining
 232          * a TGT. This will will only succeed if we have been provided with
 233          * valid authentication information by the user.
 234          */
 235         if (!result && (context->flags & SIP_SEC_FLAG_KRB5_RETRY_AUTH)) {
 236                 sip_sec_krb5_destroy_context(ctx);
 237                 result = sip_sec_krb5_obtain_tgt(ctx)          &&
 238                          sip_sec_krb5_acquire_credentials(ctx) &&
 239                          sip_sec_krb5_initialize_context(ctx,
 240                                                          in_buff,
 241                                                          out_buff,
 242                                                          service_name);
 243         }
 244
 245         /* Only retry once */
 246         context->flags &= ~SIP_SEC_FLAG_KRB5_RETRY_AUTH;
 247
 248         return(result);
 249 }
 250
 251 /**
 252  * @param message a NULL terminated string to sign
 253  */
 254 static gboolean
 255 sip_sec_make_signature__krb5(SipSecContext context,
 256                              const gchar *message,
 257                              SipSecBuffer *signature)
 258 {
 259         OM_uint32 ret;
 260         OM_uint32 minor;
 261         gss_buffer_desc input_message;
 262         gss_buffer_desc output_token;
 263
 264         input_message.value = (void *)message;
 265         input_message.length = strlen(input_message.value);
 266
 267         ret = gss_get_mic(&minor,
 268                           ((context_krb5)context)->ctx_krb5,
 269                           GSS_C_QOP_DEFAULT,
 270                           &input_message,
 271                           &output_token);
 272
 273         if (GSS_ERROR(ret)) {
 274                 sip_sec_krb5_print_gss_error("gss_get_mic", ret, minor);
 275                 SIPE_DEBUG_ERROR("sip_sec_make_signature__krb5: failed to make signature (ret=%d)", (int)ret);
 276                 return FALSE;
 277         } else {
 278                 signature->length = output_token.length;
 279                 signature->value  = g_memdup(output_token.value,
 280                                              output_token.length);
 281                 gss_release_buffer(&minor, &output_token);
 282                 return TRUE;
 283         }
 284 }
 285
 286 /**
 287  * @param message a NULL terminated string to check signature of
 288  */
 289 static gboolean
 290 sip_sec_verify_signature__krb5(SipSecContext context,
 291                                const gchar *message,
 292                                SipSecBuffer signature)
 293 {
 294         OM_uint32 ret;
 295         OM_uint32 minor;
 296         gss_buffer_desc input_message;
 297         gss_buffer_desc input_token;
 298
 299         input_message.value = (void *)message;
 300         input_message.length = strlen(input_message.value);
 301
 302         input_token.value = signature.value;
 303         input_token.length = signature.length;
 304
 305         ret = gss_verify_mic(&minor,
 306                              ((context_krb5)context)->ctx_krb5,
 307                              &input_message,
 308                              &input_token,
 309                              NULL);
 310
 311         if (GSS_ERROR(ret)) {
 312                 sip_sec_krb5_print_gss_error("gss_verify_mic", ret, minor);
 313                 SIPE_DEBUG_ERROR("sip_sec_verify_signature__krb5: failed to make signature (ret=%d)", (int)ret);
 314                 return FALSE;
 315         } else {
 316                 return TRUE;
 317         }
 318 }
 319
 320 static void
 321 sip_sec_destroy_sec_context__krb5(SipSecContext context)
 322 {
 323         sip_sec_krb5_destroy_context((context_krb5) context);
 324         g_free(context);
 325 }
 326
 327 SipSecContext
 328 sip_sec_create_context__krb5(SIPE_UNUSED_PARAMETER guint type)
 329 {
 330         context_krb5 context = g_malloc0(sizeof(struct _context_krb5));
 331         if (!context) return(NULL);
 332
 333         context->common.acquire_cred_func     = sip_sec_acquire_cred__krb5;
 334         context->common.init_context_func     = sip_sec_init_sec_context__krb5;
 335         context->common.destroy_context_func  = sip_sec_destroy_sec_context__krb5;
 336         context->common.make_signature_func   = sip_sec_make_signature__krb5;
 337         context->common.verify_signature_func = sip_sec_verify_signature__krb5;
 338
 339         context->ctx_krb5 = GSS_C_NO_CONTEXT;
 340
 341         return((SipSecContext) context);
 342 }
 343
 344 gboolean sip_sec_password__krb5(void)
 345 {
 346         /* Kerberos supports Single-Sign On */
 347         return(FALSE);
 348 }
 349
 350 static void
 351 sip_sec_krb5_print_gss_error0(char *func,
 352                              OM_uint32 status,
 353                              int type)
 354 {
 355         OM_uint32 minor;
 356         OM_uint32 message_context = 0;
 357         gss_buffer_desc status_string;
 358
 359         do {
 360                 gss_display_status(&minor,
 361                                    status,
 362                                    type,
 363                                    GSS_C_NO_OID,
 364                                    &message_context,
 365                                    &status_string);
 366
 367                 SIPE_DEBUG_ERROR("sip_sec_krb5: GSS-API error in %s (%s): %s", func, (type == GSS_C_GSS_CODE ? "GSS" : "Mech"), (char *)status_string.value);
 368                 gss_release_buffer(&minor, &status_string);
 369         } while (message_context != 0);
 370 }
 371
 372 /**
 373  * Prints out errors of GSS-API function invocation
 374  */
 375 static void sip_sec_krb5_print_gss_error(char *func, OM_uint32 ret, OM_uint32 minor)
 376 {
 377         sip_sec_krb5_print_gss_error0(func, ret, GSS_C_GSS_CODE);
 378         sip_sec_krb5_print_gss_error0(func, minor, GSS_C_MECH_CODE);
 379 }
 380
 381 /**
 382  * Prints out errors of Kerberos 5 function invocation
 383  */
 384 static void
 385 sip_sec_krb5_print_error(const gchar *func,
 386                          krb5_context context,
 387                          krb5_error_code ret);
 388
 389 /**
 390  * Obtains Kerberos TGT and stores it in default credentials cache.
 391  * Similar what kinit util would do.
 392  * Can be checked with klist util.
 393  *
 394  * kinit would require the following name:
 395  * alice@ATLANTA.LOCAL
 396  * where 'alice' is a username and
 397  * 'ATLANTA.LOCAL' is a realm (domain) .
 398  */
 399 static gboolean sip_sec_krb5_obtain_tgt(context_krb5 ctx)
 400 {
 401         krb5_context    context = NULL;
 402         krb5_error_code ret;
 403         char *realm;
 404         char *username;
 405         gchar **user_realm;
 406
 407         if (!ctx->username && !ctx->password) {
 408                 SIPE_DEBUG_ERROR_NOFORMAT("sip_sec_krb5_obtain_tgt: no valid authentication information provided");
 409                 return(FALSE);
 410         }
 411
 412         SIPE_DEBUG_INFO_NOFORMAT("sip_sec_krb5_obtain_tgt: started");
 413
 414         user_realm = g_strsplit(ctx->username, "@", 2);
 415         if (user_realm[1]) {
 416                 /* "user@domain" -> use domain as realm */
 417                 realm    = g_ascii_strup(user_realm[1], -1);
 418                 username = g_strdup(user_realm[0]);
 419         } else {
 420                 /* use provided domain as realm */
 421                 realm    = g_ascii_strup(ctx->domain, -1);
 422                 username = g_strdup(ctx->username);
 423         }
 424         g_strfreev(user_realm);
 425
 426         /* Obtait TGT */
 427         ret = krb5_init_context(&context);
 428         if (ret) {
 429                 sip_sec_krb5_print_error("krb5_init_context", context, ret);
 430         } else {
 431                 krb5_principal principal = NULL;
 432
 433                 ret = krb5_build_principal(context, &principal, strlen(realm), realm, username, NULL);
 434                 if (ret) {
 435                         sip_sec_krb5_print_error("krb5_build_principal", context, ret);
 436                 } else {
 437                         krb5_creds credentials;
 438
 439                         memset(&credentials, 0, sizeof(krb5_creds));
 440
 441                         ret = krb5_get_init_creds_password(context, &credentials, principal, (char *)ctx->password, NULL, NULL, 0, NULL, NULL);
 442                         if (ret) {
 443                                 sip_sec_krb5_print_error("krb5_get_init_creds_password", context, ret);
 444                         } else {
 445                                 krb5_ccache ccdef = NULL;
 446
 447                                 SIPE_DEBUG_INFO_NOFORMAT("sip_sec_krb5_obtain_tgt: new TGT obtained");
 448
 449                                 /* Store TGT in default credential cache */
 450                                 ret = krb5_cc_default(context, &ccdef);
 451                                 if (ret) {
 452                                         sip_sec_krb5_print_error("krb5_cc_default", context, ret);
 453                                 } else {
 454                                         /* First try without initializing */
 455                                         ret = krb5_cc_store_cred(context, ccdef, &credentials);
 456                                         if (ret) {
 457                                                 ret = krb5_cc_initialize(context, ccdef, credentials.client);
 458                                                 if (ret) {
 459                                                         sip_sec_krb5_print_error("krb5_cc_initialize", context, ret);
 460                                                 } else {
 461                                                         /* Second try after initializing the default credential cache */
 462                                                         ret = krb5_cc_store_cred(context, ccdef, &credentials);
 463                                                         if (ret) {
 464                                                                 sip_sec_krb5_print_error("krb5_cc_store_cred", context, ret);
 465                                                         } else {
 466                                                                 SIPE_DEBUG_INFO_NOFORMAT("sip_sec_krb5_obtain_tgt: new TGT stored in default credentials cache");
 467                                                         }
 468                                                 }
 469                                         }
 470                                         krb5_cc_close(context, ccdef);
 471                                 }
 472                                 krb5_free_cred_contents(context, &credentials);
 473                         }
 474                         krb5_free_principal(context, principal);
 475                 }
 476                 krb5_free_context(context);
 477         }
 478         g_free(username);
 479         g_free(realm);
 480
 481         return(!ret);
 482 }
 483
 484 static void
 485 sip_sec_krb5_print_error(const gchar *func,
 486                          krb5_context context,
 487                          krb5_error_code ret)
 488 {
 489         const gchar *error_message = krb5_get_error_message(context, ret);
 490         SIPE_DEBUG_ERROR("Kerberos 5 ERROR in %s: %s", func, error_message);
 491         krb5_free_error_message(context, error_message);
 492 }
 493
 494 /*
 495   Local Variables:
 496   mode: c
 497   c-file-style: "bsd"
 498   indent-tabs-mode: t
 499   tab-width: 8
 500   End:
 501 */