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 } *context_krb5;
  43
  44 static void sip_sec_krb5_print_gss_error(char *func, OM_uint32 ret, OM_uint32 minor);
  45
  46 static void
  47 sip_sec_krb5_obtain_tgt(const char *domain,
  48                         const char *username,
  49                         const char *password);
  50
  51 /* sip-sec-mech.h API implementation for Kerberos/GSS-API */
  52
  53 /**
  54  * Depending on Single Sign-On flag (sso),
  55  * obtains existing credentials stored in credentials cash in case of Kerberos,
  56  * or attemps to obtain TGT on its own first.
  57  */
  58 static sip_uint32
  59 sip_sec_acquire_cred__krb5(SipSecContext context,
  60                            const char *domain,
  61                            const char *username,
  62                            const char *password)
  63 {
  64         OM_uint32 ret;
  65         OM_uint32 minor;
  66         gss_cred_id_t credentials;
  67
  68         if (!context->sso) {
  69                 /* Do not use default credentials, obtain a new one and store it in cache */
  70                 sip_sec_krb5_obtain_tgt(domain, username, password);
  71         }
  72
  73         /* Acquire default user credentials */
  74         ret = gss_acquire_cred(&minor,
  75                                GSS_C_NO_NAME,
  76                                GSS_C_INDEFINITE,
  77                                GSS_C_NO_OID_SET,
  78                                GSS_C_INITIATE,
  79                                &credentials,
  80                                NULL,
  81                                NULL);
  82
  83         if (GSS_ERROR(ret)) {
  84                 sip_sec_krb5_print_gss_error("gss_acquire_cred", ret, minor);
  85                 SIPE_DEBUG_ERROR("sip_sec_acquire_cred__krb5: failed to acquire credentials (ret=%d)", (int)ret);
  86                 return SIP_SEC_E_INTERNAL_ERROR;
  87         } else {
  88                 ((context_krb5)context)->cred_krb5 = credentials;
  89                 return SIP_SEC_E_OK;
  90         }
  91 }
  92
  93 static sip_uint32
  94 sip_sec_init_sec_context__krb5(SipSecContext context,
  95                                SipSecBuffer in_buff,
  96                                SipSecBuffer *out_buff,
  97                                const char *service_name)
  98 {
  99         OM_uint32 ret;
 100         OM_uint32 minor, minor_ignore;
 101         OM_uint32 expiry;
 102         gss_buffer_desc input_token;
 103         gss_buffer_desc output_token;
 104         gss_buffer_desc input_name_buffer;
 105         gss_name_t target_name;
 106         context_krb5 ctx = (context_krb5) context;
 107
 108         SIPE_DEBUG_INFO_NOFORMAT("sip_sec_init_sec_context__krb5: started");
 109
 110         /* Delete old context first */
 111         if (ctx->ctx_krb5 != GSS_C_NO_CONTEXT) {
 112                 ret = gss_delete_sec_context(&minor,
 113                                              &(ctx->ctx_krb5),
 114                                              GSS_C_NO_BUFFER);
 115                 if (GSS_ERROR(ret)) {
 116                         sip_sec_krb5_print_gss_error("gss_delete_sec_context", ret, minor);
 117                         SIPE_DEBUG_ERROR("sip_sec_init_sec_context__krb5: failed to delete security context (ret=%d)", (int)ret);
 118                 }
 119                 ctx->ctx_krb5 = GSS_C_NO_CONTEXT;
 120         }
 121
 122         input_name_buffer.value  = (void *) service_name;
 123         input_name_buffer.length = strlen(service_name) + 1;
 124
 125         ret = gss_import_name(&minor,
 126                               &input_name_buffer,
 127                               (gss_OID) GSS_KRB5_NT_PRINCIPAL_NAME,
 128                               &target_name);
 129         if (GSS_ERROR(ret)) {
 130                 sip_sec_krb5_print_gss_error("gss_import_name", ret, minor);
 131                 SIPE_DEBUG_ERROR("sip_sec_init_sec_context__krb5: failed to construct target name (ret=%d)", (int)ret);
 132                 return SIP_SEC_E_INTERNAL_ERROR;
 133         }
 134
 135         input_token.length = in_buff.length;
 136         input_token.value = in_buff.value;
 137
 138         output_token.length = 0;
 139         output_token.value = NULL;
 140
 141         ret = gss_init_sec_context(&minor,
 142                                    ctx->cred_krb5,
 143                                    &(ctx->ctx_krb5),
 144                                    target_name,
 145                                    GSS_C_NO_OID,
 146                                    GSS_C_INTEG_FLAG,
 147                                    GSS_C_INDEFINITE,
 148                                    GSS_C_NO_CHANNEL_BINDINGS,
 149                                    &input_token,
 150                                    NULL,
 151                                    &output_token,
 152                                    NULL,
 153                                    &expiry);
 154         gss_release_name(&minor_ignore, &target_name);
 155
 156         if (GSS_ERROR(ret)) {
 157                 gss_release_buffer(&minor_ignore, &output_token);
 158                 sip_sec_krb5_print_gss_error("gss_init_sec_context", ret, minor);
 159                 SIPE_DEBUG_ERROR("sip_sec_init_sec_context__krb5: failed to initialize context (ret=%d)", (int)ret);
 160                 return SIP_SEC_E_INTERNAL_ERROR;
 161         }
 162
 163         out_buff->length = output_token.length;
 164         out_buff->value  = g_memdup(output_token.value, output_token.length);
 165         gss_release_buffer(&minor_ignore, &output_token);
 166
 167         context->expires = (int)expiry;
 168
 169         /* Authentication is completed */
 170         context->is_ready = TRUE;
 171
 172         return SIP_SEC_E_OK;
 173 }
 174
 175 /**
 176  * @param message a NULL terminated string to sign
 177  */
 178 static sip_uint32
 179 sip_sec_make_signature__krb5(SipSecContext context,
 180                              const char *message,
 181                              SipSecBuffer *signature)
 182 {
 183         OM_uint32 ret;
 184         OM_uint32 minor;
 185         gss_buffer_desc input_message;
 186         gss_buffer_desc output_token;
 187
 188         input_message.value = (void *)message;
 189         input_message.length = strlen(input_message.value);
 190
 191         ret = gss_get_mic(&minor,
 192                           ((context_krb5)context)->ctx_krb5,
 193                           GSS_C_QOP_DEFAULT,
 194                           &input_message,
 195                           &output_token);
 196
 197         if (GSS_ERROR(ret)) {
 198                 sip_sec_krb5_print_gss_error("gss_get_mic", ret, minor);
 199                 SIPE_DEBUG_ERROR("sip_sec_make_signature__krb5: failed to make signature (ret=%d)", (int)ret);
 200                 return SIP_SEC_E_INTERNAL_ERROR;
 201         } else {
 202                 signature->length = output_token.length;
 203                 signature->value  = g_memdup(output_token.value,
 204                                              output_token.length);
 205                 gss_release_buffer(&minor, &output_token);
 206                 return SIP_SEC_E_OK;
 207         }
 208 }
 209
 210 /**
 211  * @param message a NULL terminated string to check signature of
 212  */
 213 static sip_uint32
 214 sip_sec_verify_signature__krb5(SipSecContext context,
 215                                const char *message,
 216                                SipSecBuffer signature)
 217 {
 218         OM_uint32 ret;
 219         OM_uint32 minor;
 220         gss_buffer_desc input_message;
 221         gss_buffer_desc input_token;
 222
 223         input_message.value = (void *)message;
 224         input_message.length = strlen(input_message.value);
 225
 226         input_token.value = signature.value;
 227         input_token.length = signature.length;
 228
 229         ret = gss_verify_mic(&minor,
 230                              ((context_krb5)context)->ctx_krb5,
 231                              &input_message,
 232                              &input_token,
 233                              NULL);
 234
 235         if (GSS_ERROR(ret)) {
 236                 sip_sec_krb5_print_gss_error("gss_verify_mic", ret, minor);
 237                 SIPE_DEBUG_ERROR("sip_sec_verify_signature__krb5: failed to make signature (ret=%d)", (int)ret);
 238                 return SIP_SEC_E_INTERNAL_ERROR;
 239         } else {
 240                 return SIP_SEC_E_OK;
 241         }
 242 }
 243
 244 static void
 245 sip_sec_destroy_sec_context__krb5(SipSecContext context)
 246 {
 247         OM_uint32 ret;
 248         OM_uint32 minor;
 249         context_krb5 ctx = (context_krb5) context;
 250
 251         if (ctx->ctx_krb5 != GSS_C_NO_CONTEXT) {
 252                 ret = gss_delete_sec_context(&minor, &(ctx->ctx_krb5), GSS_C_NO_BUFFER);
 253                 if (GSS_ERROR(ret)) {
 254                         sip_sec_krb5_print_gss_error("gss_delete_sec_context", ret, minor);
 255                         SIPE_DEBUG_ERROR("sip_sec_destroy_sec_context__krb5: failed to delete security context (ret=%d)", (int)ret);
 256                 }
 257         }
 258
 259         if (ctx->cred_krb5) {
 260                 ret = gss_release_cred(&minor, &(ctx->cred_krb5));
 261                 if (GSS_ERROR(ret)) {
 262                         sip_sec_krb5_print_gss_error("gss_release_cred", ret, minor);
 263                         SIPE_DEBUG_ERROR("sip_sec_destroy_sec_context__krb5: failed to release credentials (ret=%d)", (int)ret);
 264                 }
 265         }
 266
 267         g_free(ctx);
 268 }
 269
 270 SipSecContext
 271 sip_sec_create_context__krb5(SIPE_UNUSED_PARAMETER guint type)
 272 {
 273         context_krb5 context = g_malloc0(sizeof(struct _context_krb5));
 274         if (!context) return(NULL);
 275
 276         context->common.acquire_cred_func     = sip_sec_acquire_cred__krb5;
 277         context->common.init_context_func     = sip_sec_init_sec_context__krb5;
 278         context->common.destroy_context_func  = sip_sec_destroy_sec_context__krb5;
 279         context->common.make_signature_func   = sip_sec_make_signature__krb5;
 280         context->common.verify_signature_func = sip_sec_verify_signature__krb5;
 281
 282         context->ctx_krb5 = GSS_C_NO_CONTEXT;
 283
 284         return((SipSecContext) context);
 285 }
 286
 287 gboolean sip_sec_password__krb5(void)
 288 {
 289         /* Kerberos supports Single-Sign On */
 290         return(FALSE);
 291 }
 292
 293 static void
 294 sip_sec_krb5_print_gss_error0(char *func,
 295                              OM_uint32 status,
 296                              int type)
 297 {
 298         OM_uint32 minor;
 299         OM_uint32 message_context = 0;
 300         gss_buffer_desc status_string;
 301
 302         do {
 303                 gss_display_status(&minor,
 304                                    status,
 305                                    type,
 306                                    GSS_C_NO_OID,
 307                                    &message_context,
 308                                    &status_string);
 309
 310                 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);
 311                 gss_release_buffer(&minor, &status_string);
 312         } while (message_context != 0);
 313 }
 314
 315 /**
 316  * Prints out errors of GSS-API function invocation
 317  */
 318 static void sip_sec_krb5_print_gss_error(char *func, OM_uint32 ret, OM_uint32 minor)
 319 {
 320         sip_sec_krb5_print_gss_error0(func, ret, GSS_C_GSS_CODE);
 321         sip_sec_krb5_print_gss_error0(func, minor, GSS_C_MECH_CODE);
 322 }
 323
 324 /**
 325  * Prints out errors of Kerberos 5 function invocation
 326  */
 327 static void
 328 sip_sec_krb5_print_error(const char *func,
 329                          krb5_context context,
 330                          krb5_error_code ret);
 331
 332 /**
 333  * Obtains Kerberos TGT and stores it in default credentials cache.
 334  * Similar what kinit util would do.
 335  * Can be checked with klist util.
 336  *
 337  * kinit would require the following name:
 338  * alice@ATLANTA.LOCAL
 339  * where 'alice' is a username and
 340  * 'ATLANTA.LOCAL' is a realm (domain) .
 341  */
 342 static void
 343 sip_sec_krb5_obtain_tgt(const char *domain_in,
 344                         const char *username_in,
 345                         const char *password)
 346 {
 347         krb5_context    context;
 348         krb5_principal  principal = NULL;
 349         krb5_creds      credentials;
 350         krb5_ccache     ccdef;
 351         krb5_error_code ret;
 352         char *realm;
 353         char *username;
 354         gchar **user_realm;
 355
 356         SIPE_DEBUG_INFO_NOFORMAT("sip_sec_krb5_obtain_tgt: started");
 357
 358         memset(&credentials, 0, sizeof(krb5_creds));
 359
 360         user_realm = g_strsplit(username_in, "@", 2);
 361         if (user_realm && user_realm[1]) {
 362                 /* "user@domain" -> use domain as realm */
 363                 realm    = g_ascii_strup(user_realm[1], -1);
 364                 username = g_strdup(user_realm[0]);
 365         } else {
 366                 /* use provided domain as realm */
 367                 realm    = g_ascii_strup(domain_in ? domain_in : "", -1);
 368                 username = g_strdup(username_in);
 369         }
 370         g_strfreev(user_realm);
 371
 372         /* Obtait TGT */
 373         if ((ret = krb5_init_context(&context))) {
 374                 sip_sec_krb5_print_error("krb5_init_context", context, ret);
 375         }
 376
 377         if (!ret && (ret = krb5_build_principal(context, &principal, strlen(realm), realm, username, NULL))) {
 378                 sip_sec_krb5_print_error("krb5_build_principal", context, ret);
 379         }
 380         g_free(username);
 381         g_free(realm);
 382
 383         if (!ret && (ret = krb5_get_init_creds_password(context, &credentials, principal, (char *)password, NULL, NULL, 0, NULL, NULL))) {
 384                 sip_sec_krb5_print_error("krb5_get_init_creds_password", context, ret);
 385         }
 386
 387         if (!ret) {
 388                 SIPE_DEBUG_INFO_NOFORMAT("sip_sec_krb5_obtain_tgt: new TGT obtained");
 389         }
 390
 391
 392         /* Store TGT in default credential cache */
 393         if (!ret && (ret = krb5_cc_default(context, &ccdef))) {
 394                 sip_sec_krb5_print_error("krb5_cc_default", context, ret);
 395         }
 396
 397         if (!ret && (ret = krb5_cc_initialize(context, ccdef, credentials.client))) {
 398                 sip_sec_krb5_print_error("krb5_cc_initialize", context, ret);
 399         }
 400
 401         if (!ret && (ret = krb5_cc_store_cred(context, ccdef, &credentials))) {
 402                 sip_sec_krb5_print_error("krb5_cc_store_cred", context, ret);
 403         }
 404
 405         if (!ret) {
 406                 SIPE_DEBUG_INFO_NOFORMAT("sip_sec_krb5_obtain_tgt: new TGT stored in default credentials cache");
 407         }
 408
 409
 410         if (principal)
 411                 krb5_free_principal(context, principal);
 412
 413         if (context)
 414                 krb5_free_context(context);
 415 }
 416
 417 static void
 418 sip_sec_krb5_print_error(const char *func,
 419                          krb5_context context,
 420                          krb5_error_code ret)
 421 {
 422         const char *error_message = krb5_get_error_message(context, ret);
 423         SIPE_DEBUG_ERROR("Kerberos 5 ERROR in %s: %s", func, error_message);
 424         krb5_free_error_message(context, error_message);
 425 }
 426
 427 /*
 428   Local Variables:
 429   mode: c
 430   c-file-style: "bsd"
 431   indent-tabs-mode: t
 432   tab-width: 8
 433   End:
 434 */