src/peer_proxy_negotiate_auth.cc

   1 /*
   2  * -----------------------------------------------------------------------------
   3  *
   4  * Author: Markus Moeller (markus_moeller at compuserve.com)
   5  *
   6  * Copyright (C) 2007 Markus Moeller. All rights reserved.
   7  *
   8  *   This program is free software; you can redistribute it and/or modify
   9  *   it under the terms of the GNU General Public License as published by
  10  *   the Free Software Foundation; either version 2 of the License, or
  11  *   (at your option) any later version.
  12  *
  13  *   This program is distributed in the hope that it will be useful,
  14  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *   GNU General Public License for more details.
  17  *
  18  *   You should have received a copy of the GNU General Public License
  19  *   along with this program; if not, write to the Free Software
  20  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307, USA.
  21  *
  22  * -----------------------------------------------------------------------------
  23  */
  24 /*
  25  * Hosted at http://sourceforge.net/projects/squidkerbauth
  26  */
  27
  28 #include "squid.h"
  29
  30 #if HAVE_KRB5 && HAVE_GSSAPI
  31
  32 #include "base64.h"
  33 #include "Debug.h"
  34 #include "peer_proxy_negotiate_auth.h"
  35
  36 #ifdef __cplusplus
  37 extern "C" {
  38 #endif
  39
  40 #if HAVE_PROFILE_H
  41 #include <profile.h>
  42 #endif                          /* HAVE_PROFILE_H */
  43 #if HAVE_KRB5_H
  44 #if HAVE_BROKEN_SOLARIS_KRB5_H
  45 #if defined(__cplusplus)
  46 #define KRB5INT_BEGIN_DECLS     extern "C" {
  47 #define KRB5INT_END_DECLS
  48     KRB5INT_BEGIN_DECLS
  49 #endif
  50 #endif
  51 #include <krb5.h>
  52 #elif HAVE_ET_COM_ERR_H
  53 #include <et/com_err.h>
  54 #endif                          /* HAVE_COM_ERR_H */
  55 #if HAVE_COM_ERR_H
  56 #include <com_err.h>
  57 #endif                          /* HAVE_COM_ERR_H */
  58
  59 #if HAVE_GSSAPI_GSSAPI_H
  60 #include <gssapi/gssapi.h>
  61 #elif HAVE_GSSAPI_H
  62 #include <gssapi.h>
  63 #endif                          /* HAVE_GSSAPI_H */
  64 #if HAVE_GSSAPI_GSSAPI_EXT_H
  65 #include <gssapi/gssapi_ext.h>
  66 #endif                          /* HAVE_GSSAPI_GSSAPI_EXT_H */
  67 #if HAVE_GSSAPI_GSSAPI_KRB5_H
  68 #include <gssapi/gssapi_krb5.h>
  69 #endif                          /* HAVE_GSSAPI_GSSAPI_KRB5_H */
  70 #if HAVE_GSSAPI_GSSAPI_GENERIC_H
  71 #include <gssapi/gssapi_generic.h>
  72 #endif                          /* HAVE_GSSAPI_GSSAPI_GENERIC_H */
  73
  74 #ifndef gss_nt_service_name
  75 #define gss_nt_service_name GSS_C_NT_HOSTBASED_SERVICE
  76 #endif
  77
  78 #if !HAVE_ERROR_MESSAGE && HAVE_KRB5_GET_ERR_TEXT
  79 #define error_message(code) krb5_get_err_text(kparam.context,code)
  80 #elif  !HAVE_ERROR_MESSAGE && HAVE_KRB5_GET_ERROR_MESSAGE
  81 #define error_message(code) krb5_get_error_message(kparam.context,code)
  82 #elif !HAVE_ERROR_MESSAGE
  83     static char err_code[17];
  84     const char *KRB5_CALLCONV
  85     error_message(long code) {
  86         snprintf(err_code,16,"%ld",code);
  87         return err_code;
  88     }
  89 #endif
  90
  91 #ifndef gss_mech_spnego
  92     static gss_OID_desc _gss_mech_spnego =
  93         { 6, (void *) "\x2b\x06\x01\x05\x05\x02" };
  94     gss_OID gss_mech_spnego = &_gss_mech_spnego;
  95 #endif
  96
  97 #if HAVE_NAS_KERBEROS
  98 #include <ibm_svc/krb5_svc.h>
  99     const char *KRB5_CALLCONV error_message(long code) {
 100         char *msg = NULL;
 101         krb5_svc_get_msg(code, &msg);
 102         return msg;
 103     }
 104 #endif
 105
 106     /*
 107      * Kerberos context and cache structure
 108      * Caches authentication details to reduce
 109      * number of authentication requests to kdc
 110      */
 111     static struct kstruct {
 112         krb5_context context;
 113         krb5_ccache cc;
 114     } kparam = {
 115         NULL, NULL};
 116
 117     /*
 118      * krb5_create_cache creates a Kerberos file credential cache or a memory
 119      * credential cache if supported. The initial key for the principal
 120      * principal_name is extracted from the keytab keytab_filename.
 121      *
 122      * If keytab_filename is NULL the default will be used.
 123      * If principal_name is NULL the first working entry of the keytab will be used.
 124      */
 125     int krb5_create_cache(char *keytab_filename, char *principal_name);
 126
 127     /*
 128      * krb5_cleanup clears used Keberos memory
 129      */
 130     void krb5_cleanup(void);
 131
 132     /*
 133      * check_gss_err checks for gssapi error codes, extracts the error message
 134      * and prints it.
 135      */
 136     int check_gss_err(OM_uint32 major_status, OM_uint32 minor_status,
 137                       const char *function);
 138
 139     int check_gss_err(OM_uint32 major_status, OM_uint32 minor_status,
 140                       const char *function) {
 141         if (GSS_ERROR(major_status)) {
 142             OM_uint32 maj_stat, min_stat;
 143             OM_uint32 msg_ctx = 0;
 144             gss_buffer_desc status_string;
 145             char buf[1024];
 146             size_t len;
 147
 148             len = 0;
 149             msg_ctx = 0;
 150             while (!msg_ctx) {
 151                 /* convert major status code (GSS-API error) to text */
 152                 maj_stat = gss_display_status(&min_stat, major_status,
 153                                               GSS_C_GSS_CODE, GSS_C_NULL_OID, &msg_ctx, &status_string);
 154                 if (maj_stat == GSS_S_COMPLETE) {
 155                     if (sizeof(buf) > len + status_string.length + 1) {
 156                         memcpy(buf + len, status_string.value,
 157                                status_string.length);
 158                         len += status_string.length;
 159                     }
 160                     gss_release_buffer(&min_stat, &status_string);
 161                     break;
 162                 }
 163                 gss_release_buffer(&min_stat, &status_string);
 164             }
 165             if (sizeof(buf) > len + 2) {
 166                 strcpy(buf + len, ". ");
 167                 len += 2;
 168             }
 169             msg_ctx = 0;
 170             while (!msg_ctx) {
 171                 /* convert minor status code (underlying routine error) to text */
 172                 maj_stat = gss_display_status(&min_stat, minor_status,
 173                                               GSS_C_MECH_CODE, GSS_C_NULL_OID, &msg_ctx, &status_string);
 174                 if (maj_stat == GSS_S_COMPLETE) {
 175                     if (sizeof(buf) > len + status_string.length) {
 176                         memcpy(buf + len, status_string.value,
 177                                status_string.length);
 178                         len += status_string.length;
 179                     }
 180                     gss_release_buffer(&min_stat, &status_string);
 181                     break;
 182                 }
 183                 gss_release_buffer(&min_stat, &status_string);
 184             }
 185             debugs(11, 5, HERE << function << "failed: " << buf);
 186             return (1);
 187         }
 188         return (0);
 189     }
 190
 191     void krb5_cleanup() {
 192         debugs(11, 5, HERE << "Cleanup kerberos context");
 193         if (kparam.context) {
 194             if (kparam.cc)
 195                 krb5_cc_destroy(kparam.context, kparam.cc);
 196             kparam.cc = NULL;
 197             krb5_free_context(kparam.context);
 198             kparam.context = NULL;
 199         }
 200     }
 201
 202     int krb5_create_cache(char *kf, char *pn) {
 203
 204 #define KT_PATH_MAX 256
 205 #define MAX_RENEW_TIME "365d"
 206 #define DEFAULT_SKEW (krb5_deltat) 600
 207
 208         static char *keytab_filename = NULL, *principal_name = NULL;
 209         static krb5_keytab keytab = 0;
 210         static krb5_keytab_entry entry;
 211         static krb5_kt_cursor cursor;
 212         static krb5_creds *creds = NULL;
 213 #if HAVE_HEIMDAL_KERBEROS
 214         static krb5_creds creds2;
 215 #endif
 216         static krb5_principal principal = NULL;
 217         static krb5_deltat skew;
 218
 219         krb5_get_init_creds_opt options;
 220         krb5_error_code code = 0;
 221         krb5_deltat rlife;
 222 #if HAVE_PROFILE_H && HAVE_KRB5_GET_PROFILE && HAVE_PROFILE_GET_INTEGER && HAVE_PROFILE_RELEASE
 223         profile_t profile;
 224 #endif
 225 #if HAVE_HEIMDAL_KERBEROS
 226         krb5_kdc_flags flags;
 227         krb5_realm *client_realm;
 228 #endif
 229         char *mem_cache;
 230
 231 restart:
 232         /*
 233          * Check if credentials need to be renewed
 234          */
 235         if (creds &&
 236                 (creds->times.endtime - time(0) > skew) &&
 237                 (creds->times.renew_till - time(0) > 2 * skew)) {
 238             if (creds->times.endtime - time(0) < 2 * skew) {
 239 #if !HAVE_HEIMDAL_KERBEROS
 240                 /* renew ticket */
 241                 code =
 242                     krb5_get_renewed_creds(kparam.context, creds, principal,
 243                                            kparam.cc, NULL);
 244 #else
 245                 /* renew ticket */
 246                 flags.i = 0;
 247                 flags.b.renewable = flags.b.renew = 1;
 248
 249                 code =
 250                     krb5_cc_get_principal(kparam.context, kparam.cc,
 251                                           &creds2.client);
 252                 if (code) {
 253                     debugs(11, 5,
 254                            HERE <<
 255                            "Error while getting principal from credential cache : "
 256                            << error_message(code));
 257                     return (1);
 258                 }
 259                 client_realm = krb5_princ_realm(kparam.context, creds2.client);
 260                 code =
 261                     krb5_make_principal(kparam.context, &creds2.server,
 262                                         *client_realm, KRB5_TGS_NAME, *client_realm, NULL);
 263                 if (code) {
 264                     debugs(11, 5,
 265                            HERE << "Error while getting krbtgt principal : " <<
 266                            error_message(code));
 267                     return (1);
 268                 }
 269                 code =
 270                     krb5_get_kdc_cred(kparam.context, kparam.cc, flags, NULL,
 271                                       NULL, &creds2, &creds);
 272                 krb5_free_creds(kparam.context, &creds2);
 273 #endif
 274                 if (code) {
 275                     if (code == KRB5KRB_AP_ERR_TKT_EXPIRED) {
 276                         krb5_free_creds(kparam.context, creds);
 277                         creds = NULL;
 278                         /* this can happen because of clock skew */
 279                         goto restart;
 280                     }
 281                     debugs(11, 5,
 282                            HERE << "Error while get credentials : " <<
 283                            error_message(code));
 284                     return (1);
 285                 }
 286             }
 287         } else {
 288             /* reinit */
 289             if (!kparam.context) {
 290                 code = krb5_init_context(&kparam.context);
 291                 if (code) {
 292                     debugs(11, 5,
 293                            HERE << "Error while initialising Kerberos library : "
 294                            << error_message(code));
 295                     return (1);
 296                 }
 297             }
 298 #if HAVE_PROFILE_H && HAVE_KRB5_GET_PROFILE && HAVE_PROFILE_GET_INTEGER && HAVE_PROFILE_RELEASE
 299             code = krb5_get_profile(kparam.context, &profile);
 300             if (code) {
 301                 if (profile)
 302                     profile_release(profile);
 303                 debugs(11, 5,
 304                        HERE << "Error while getting profile : " <<
 305                        error_message(code));
 306                 return (1);
 307             }
 308             code =
 309                 profile_get_integer(profile, "libdefaults", "clockskew", 0,
 310                                     5 * 60, &skew);
 311             if (profile)
 312                 profile_release(profile);
 313             if (code) {
 314                 debugs(11, 5,
 315                        HERE << "Error while getting clockskew : " <<
 316                        error_message(code));
 317                 return (1);
 318             }
 319 #elif HAVE_KRB5_GET_MAX_TIME_SKEW && HAVE_HEIMDAL_KERBEROS
 320             skew = krb5_get_max_time_skew(kparam.context);
 321 #elif HAVE_MAX_SKEW_IN_KRB5_CONTEXT && HAVE_HEIMDAL_KERBEROS
 322             skew = kparam.context->max_skew;
 323 #else
 324             skew = DEFAULT_SKEW;
 325 #endif
 326
 327             if (!kf) {
 328                 char buf[KT_PATH_MAX], *p;
 329
 330                 krb5_kt_default_name(kparam.context, buf, KT_PATH_MAX);
 331                 p = strchr(buf, ':');
 332                 if (p)
 333                     ++p;
 334                 if (keytab_filename)
 335                     xfree(keytab_filename);
 336                 keytab_filename = xstrdup(p ? p : buf);
 337             } else {
 338                 keytab_filename = xstrdup(kf);
 339             }
 340
 341             code = krb5_kt_resolve(kparam.context, keytab_filename, &keytab);
 342             if (code) {
 343                 debugs(11, 5,
 344                        HERE << "Error while resolving keytab filename " <<
 345                        keytab_filename << " : " << error_message(code));
 346                 return (1);
 347             }
 348
 349             if (!pn) {
 350                 code = krb5_kt_start_seq_get(kparam.context, keytab, &cursor);
 351                 if (code) {
 352                     debugs(11, 5,
 353                            HERE << "Error while starting keytab scan : " <<
 354                            error_message(code));
 355                     return (1);
 356                 }
 357                 code =
 358                     krb5_kt_next_entry(kparam.context, keytab, &entry, &cursor);
 359                 krb5_copy_principal(kparam.context, entry.principal,
 360                                     &principal);
 361                 if (code && code != KRB5_KT_END) {
 362                     debugs(11, 5,
 363                            HERE << "Error while scanning keytab : " <<
 364                            error_message(code));
 365                     return (1);
 366                 }
 367
 368                 code = krb5_kt_end_seq_get(kparam.context, keytab, &cursor);
 369                 if (code) {
 370                     debugs(11, 5,
 371                            HERE << "Error while ending keytab scan : " <<
 372                            error_message(code));
 373                     return (1);
 374                 }
 375 #if HAVE_HEIMDAL_KERBEROS || ( HAVE_KRB5_KT_FREE_ENTRY && HAVE_DECL_KRB5_KT_FREE_ENTRY)
 376                 code = krb5_kt_free_entry(kparam.context, &entry);
 377 #else
 378                 code = krb5_free_keytab_entry_contents(kparam.context, &entry);
 379 #endif
 380                 if (code) {
 381                     debugs(11, 5,
 382                            HERE << "Error while freeing keytab entry : " <<
 383                            error_message(code));
 384                     return (1);
 385                 }
 386
 387             } else {
 388                 principal_name = xstrdup(pn);
 389             }
 390
 391             if (!principal) {
 392                 code =
 393                     krb5_parse_name(kparam.context, principal_name, &principal);
 394                 if (code) {
 395                     debugs(11, 5,
 396                            HERE << "Error while parsing principal name " <<
 397                            principal_name << " : " << error_message(code));
 398                     return (1);
 399                 }
 400             }
 401
 402             creds = (krb5_creds *) xmalloc(sizeof(*creds));
 403             memset(creds, 0, sizeof(*creds));
 404             krb5_get_init_creds_opt_init(&options);
 405             code = krb5_string_to_deltat((char *) MAX_RENEW_TIME, &rlife);
 406             if (code != 0 || rlife == 0) {
 407                 debugs(11, 5,
 408                        HERE << "Error bad lifetime value " << MAX_RENEW_TIME <<
 409                        " : " << error_message(code));
 410                 return (1);
 411             }
 412             krb5_get_init_creds_opt_set_renew_life(&options, rlife);
 413
 414             code =
 415                 krb5_get_init_creds_keytab(kparam.context, creds, principal,
 416                                            keytab, 0, NULL, &options);
 417             if (code) {
 418                 debugs(11, 5,
 419                        HERE <<
 420                        "Error while initializing credentials from keytab : " <<
 421                        error_message(code));
 422                 return (1);
 423             }
 424 #if !HAVE_KRB5_MEMORY_CACHE
 425             mem_cache =
 426                 (char *) xmalloc(strlen("FILE:/tmp/peer_proxy_negotiate_auth_")
 427                                  + 16);
 428             snprintf(mem_cache,
 429                      strlen("FILE:/tmp/peer_proxy_negotiate_auth_") + 16,
 430                      "FILE:/tmp/peer_proxy_negotiate_auth_%d", (int) getpid());
 431 #else
 432             mem_cache =
 433                 (char *) xmalloc(strlen("MEMORY:peer_proxy_negotiate_auth_") +
 434                                  16);
 435             snprintf(mem_cache,
 436                      strlen("MEMORY:peer_proxy_negotiate_auth_") + 16,
 437                      "MEMORY:peer_proxy_negotiate_auth_%d", (int) getpid());
 438 #endif
 439
 440             setenv("KRB5CCNAME", mem_cache, 1);
 441             code = krb5_cc_resolve(kparam.context, mem_cache, &kparam.cc);
 442             if (mem_cache)
 443                 xfree(mem_cache);
 444             if (code) {
 445                 debugs(11, 5,
 446                        HERE << "Error while resolving memory credential cache : "
 447                        << error_message(code));
 448                 return (1);
 449             }
 450             code = krb5_cc_initialize(kparam.context, kparam.cc, principal);
 451             if (code) {
 452                 debugs(11, 5,
 453                        HERE <<
 454                        "Error while initializing memory credential cache : " <<
 455                        error_message(code));
 456                 return (1);
 457             }
 458             code = krb5_cc_store_cred(kparam.context, kparam.cc, creds);
 459             if (code) {
 460                 debugs(11, 5,
 461                        HERE << "Error while storing credentials : " <<
 462                        error_message(code));
 463                 return (1);
 464             }
 465
 466             if (!creds->times.starttime)
 467                 creds->times.starttime = creds->times.authtime;
 468         }
 469         return (0);
 470     }
 471
 472     /*
 473      * peer_proxy_negotiate_auth gets a GSSAPI token for principal_name
 474      * and base64 encodes it.
 475      */
 476     char *peer_proxy_negotiate_auth(char *principal_name, char *proxy) {
 477         int rc = 0;
 478         OM_uint32 major_status, minor_status;
 479         gss_ctx_id_t gss_context = GSS_C_NO_CONTEXT;
 480         gss_name_t server_name = GSS_C_NO_NAME;
 481         gss_buffer_desc service = GSS_C_EMPTY_BUFFER;
 482         gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
 483         gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
 484         char *token = NULL;
 485
 486         setbuf(stdout, NULL);
 487         setbuf(stdin, NULL);
 488
 489         if (!proxy) {
 490             debugs(11, 5, HERE << "Error : No proxy server name");
 491             return NULL;
 492         }
 493
 494         if (principal_name)
 495             debugs(11, 5,
 496                    HERE << "Creating credential cache for " << principal_name);
 497         else
 498             debugs(11, 5, HERE << "Creating credential cache");
 499         rc = krb5_create_cache(NULL, principal_name);
 500         if (rc) {
 501             debugs(11, 5, HERE << "Error : Failed to create Kerberos cache");
 502             krb5_cleanup();
 503             return NULL;
 504         }
 505
 506         service.value = (void *) xmalloc(strlen("HTTP") + strlen(proxy) + 2);
 507         snprintf((char *) service.value, strlen("HTTP") + strlen(proxy) + 2,
 508                  "%s@%s", "HTTP", proxy);
 509         service.length = strlen((char *) service.value);
 510
 511         debugs(11, 5, HERE << "Import gss name");
 512         major_status = gss_import_name(&minor_status, &service,
 513                                        gss_nt_service_name, &server_name);
 514
 515         if (check_gss_err(major_status, minor_status, "gss_import_name()"))
 516             goto cleanup;
 517
 518         debugs(11, 5, HERE << "Initialize gss security context");
 519         major_status = gss_init_sec_context(&minor_status,
 520                                             GSS_C_NO_CREDENTIAL,
 521                                             &gss_context,
 522                                             server_name,
 523                                             gss_mech_spnego,
 524                                             0,
 525                                             0,
 526                                             GSS_C_NO_CHANNEL_BINDINGS,
 527                                             &input_token, NULL, &output_token, NULL, NULL);
 528
 529         if (check_gss_err(major_status, minor_status, "gss_init_sec_context()"))
 530             goto cleanup;
 531
 532         debugs(11, 5, HERE << "Got token with length " << output_token.length);
 533         if (output_token.length) {
 534
 535             token =
 536                 (char *) base64_encode_bin((const char *) output_token.value,
 537                                            output_token.length);
 538         }
 539
 540 cleanup:
 541         gss_delete_sec_context(&minor_status, &gss_context, NULL);
 542         gss_release_buffer(&minor_status, &service);
 543         gss_release_buffer(&minor_status, &input_token);
 544         gss_release_buffer(&minor_status, &output_token);
 545         gss_release_name(&minor_status, &server_name);
 546
 547         return token;
 548     }
 549
 550 #ifdef __cplusplus
 551 }
 552 #endif
 553 #endif /* HAVE_KRB5 && HAVE_GSSAPI */