windows/wingss.c

   1 #ifndef NO_GSSAPI
   2
   3 #include "putty.h"
   4
   5 #include <security.h>
   6
   7 #include "pgssapi.h"
   8 #include "sshgss.h"
   9 #include "sshgssc.h"
  10
  11 #include "misc.h"
  12
  13 /* Windows code to set up the GSSAPI library list. */
  14
  15 const int ngsslibs = 3;
  16 const char *const gsslibnames[3] = {
  17     "MIT Kerberos GSSAPI32.DLL",
  18     "Microsoft SSPI SECUR32.DLL",
  19     "User-specified GSSAPI DLL",
  20 };
  21 const struct keyvalwhere gsslibkeywords[] = {
  22     { "gssapi32", 0, -1, -1 },
  23     { "sspi", 1, -1, -1 },
  24     { "custom", 2, -1, -1 },
  25 };
  26
  27 DECL_WINDOWS_FUNCTION(static, SECURITY_STATUS,
  28                       AcquireCredentialsHandleA,
  29                       (SEC_CHAR *, SEC_CHAR *, ULONG, PLUID,
  30                        PVOID, SEC_GET_KEY_FN, PVOID, PCredHandle, PTimeStamp));
  31 DECL_WINDOWS_FUNCTION(static, SECURITY_STATUS,
  32                       InitializeSecurityContextA,
  33                       (PCredHandle, PCtxtHandle, SEC_CHAR *, ULONG, ULONG,
  34                        ULONG, PSecBufferDesc, ULONG, PCtxtHandle,
  35                        PSecBufferDesc, PULONG, PTimeStamp));
  36 DECL_WINDOWS_FUNCTION(static, SECURITY_STATUS,
  37                       FreeContextBuffer,
  38                       (PVOID));
  39 DECL_WINDOWS_FUNCTION(static, SECURITY_STATUS,
  40                       FreeCredentialsHandle,
  41                       (PCredHandle));
  42 DECL_WINDOWS_FUNCTION(static, SECURITY_STATUS,
  43                       DeleteSecurityContext,
  44                       (PCtxtHandle));
  45 DECL_WINDOWS_FUNCTION(static, SECURITY_STATUS,
  46                       QueryContextAttributesA,
  47                       (PCtxtHandle, ULONG, PVOID));
  48 DECL_WINDOWS_FUNCTION(static, SECURITY_STATUS,
  49                       MakeSignature,
  50                       (PCtxtHandle, ULONG, PSecBufferDesc, ULONG));
  51
  52 typedef struct winSsh_gss_ctx {
  53     unsigned long maj_stat;
  54     unsigned long min_stat;
  55     CredHandle cred_handle;
  56     CtxtHandle context;
  57     PCtxtHandle context_handle;
  58     TimeStamp expiry;
  59 } winSsh_gss_ctx;
  60
  61
  62 const Ssh_gss_buf gss_mech_krb5={9,"\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"};
  63
  64 const char *gsslogmsg = NULL;
  65
  66 static void ssh_sspi_bind_fns(struct ssh_gss_library *lib);
  67
  68 struct ssh_gss_liblist *ssh_gss_setup(const Config *cfg)
  69 {
  70     HMODULE module;
  71     HKEY regkey;
  72     struct ssh_gss_liblist *list = snew(struct ssh_gss_liblist);
  73
  74     list->libraries = snewn(3, struct ssh_gss_library);
  75     list->nlibraries = 0;
  76
  77     /* MIT Kerberos GSSAPI implementation */
  78     /* TODO: For 64-bit builds, check for gssapi64.dll */
  79     module = NULL;
  80     if (RegOpenKey(HKEY_LOCAL_MACHINE, "SOFTWARE\\MIT\\Kerberos", &regkey)
  81         == ERROR_SUCCESS) {
  82         DWORD type, size;
  83         LONG ret;
  84         char *buffer;
  85
  86         /* Find out the string length */
  87         ret = RegQueryValueEx(regkey, "InstallDir", NULL, &type, NULL, &size);
  88
  89         if (ret == ERROR_SUCCESS && type == REG_SZ) {
  90             buffer = snewn(size + 20, char);
  91             ret = RegQueryValueEx(regkey, "InstallDir", NULL,
  92                                   &type, buffer, &size);
  93             if (ret == ERROR_SUCCESS && type == REG_SZ) {
  94                 strcat(buffer, "\\bin\\gssapi32.dll");
  95                 module = LoadLibrary(buffer);
  96             }
  97             sfree(buffer);
  98         }
  99         RegCloseKey(regkey);
 100     }
 101     if (module) {
 102         struct ssh_gss_library *lib =
 103             &list->libraries[list->nlibraries++];
 104
 105         lib->id = 0;
 106         lib->gsslogmsg = "Using GSSAPI from GSSAPI32.DLL";
 107         lib->handle = (void *)module;
 108
 109 #define BIND_GSS_FN(name) \
 110     lib->u.gssapi.name = (t_gss_##name) GetProcAddress(module, "gss_" #name)
 111
 112         BIND_GSS_FN(delete_sec_context);
 113         BIND_GSS_FN(display_status);
 114         BIND_GSS_FN(get_mic);
 115         BIND_GSS_FN(import_name);
 116         BIND_GSS_FN(init_sec_context);
 117         BIND_GSS_FN(release_buffer);
 118         BIND_GSS_FN(release_cred);
 119         BIND_GSS_FN(release_name);
 120
 121 #undef BIND_GSS_FN
 122
 123         ssh_gssapi_bind_fns(lib);
 124     }
 125
 126     /* Microsoft SSPI Implementation */
 127     module = load_system32_dll("secur32.dll");
 128     if (module) {
 129         struct ssh_gss_library *lib =
 130             &list->libraries[list->nlibraries++];
 131
 132         lib->id = 1;
 133         lib->gsslogmsg = "Using SSPI from SECUR32.DLL";
 134         lib->handle = (void *)module;
 135
 136         GET_WINDOWS_FUNCTION(module, AcquireCredentialsHandleA);
 137         GET_WINDOWS_FUNCTION(module, InitializeSecurityContextA);
 138         GET_WINDOWS_FUNCTION(module, FreeContextBuffer);
 139         GET_WINDOWS_FUNCTION(module, FreeCredentialsHandle);
 140         GET_WINDOWS_FUNCTION(module, DeleteSecurityContext);
 141         GET_WINDOWS_FUNCTION(module, QueryContextAttributesA);
 142         GET_WINDOWS_FUNCTION(module, MakeSignature);
 143
 144         ssh_sspi_bind_fns(lib);
 145     }
 146
 147     /*
 148      * Custom GSSAPI DLL.
 149      */
 150     module = NULL;
 151     if (cfg->ssh_gss_custom.path[0]) {
 152         module = LoadLibrary(cfg->ssh_gss_custom.path);
 153     }
 154     if (module) {
 155         struct ssh_gss_library *lib =
 156             &list->libraries[list->nlibraries++];
 157
 158         lib->id = 2;
 159         lib->gsslogmsg = dupprintf("Using GSSAPI from user-specified"
 160                                    " library '%s'", cfg->ssh_gss_custom.path);
 161         lib->handle = (void *)module;
 162
 163 #define BIND_GSS_FN(name) \
 164     lib->u.gssapi.name = (t_gss_##name) GetProcAddress(module, "gss_" #name)
 165
 166         BIND_GSS_FN(delete_sec_context);
 167         BIND_GSS_FN(display_status);
 168         BIND_GSS_FN(get_mic);
 169         BIND_GSS_FN(import_name);
 170         BIND_GSS_FN(init_sec_context);
 171         BIND_GSS_FN(release_buffer);
 172         BIND_GSS_FN(release_cred);
 173         BIND_GSS_FN(release_name);
 174
 175 #undef BIND_GSS_FN
 176
 177         ssh_gssapi_bind_fns(lib);
 178     }
 179
 180
 181     return list;
 182 }
 183
 184 void ssh_gss_cleanup(struct ssh_gss_liblist *list)
 185 {
 186     int i;
 187
 188     /*
 189      * LoadLibrary and FreeLibrary are defined to employ reference
 190      * counting in the case where the same library is repeatedly
 191      * loaded, so even in a multiple-sessions-per-process context
 192      * (not that we currently expect ever to have such a thing on
 193      * Windows) it's safe to naively FreeLibrary everything here
 194      * without worrying about destroying it under the feet of
 195      * another SSH instance still using it.
 196      */
 197     for (i = 0; i < list->nlibraries; i++) {
 198         FreeLibrary((HMODULE)list->libraries[i].handle);
 199         if (list->libraries[i].id == 2) {
 200             /* The 'custom' id involves a dynamically allocated message.
 201              * Note that we must cast away the 'const' to free it. */
 202             sfree((char *)list->libraries[i].gsslogmsg);
 203         }
 204     }
 205     sfree(list->libraries);
 206     sfree(list);
 207 }
 208
 209 static Ssh_gss_stat ssh_sspi_indicate_mech(struct ssh_gss_library *lib,
 210                                            Ssh_gss_buf *mech)
 211 {
 212     *mech = gss_mech_krb5;
 213     return SSH_GSS_OK;
 214 }
 215
 216
 217 static Ssh_gss_stat ssh_sspi_import_name(struct ssh_gss_library *lib,
 218                                          char *host, Ssh_gss_name *srv_name)
 219 {
 220     char *pStr;
 221
 222     /* Check hostname */
 223     if (host == NULL) return SSH_GSS_FAILURE;
 224
 225     /* copy it into form host/FQDN */
 226     pStr = dupcat("host/", host, NULL);
 227
 228     *srv_name = (Ssh_gss_name) pStr;
 229
 230     return SSH_GSS_OK;
 231 }
 232
 233 static Ssh_gss_stat ssh_sspi_acquire_cred(struct ssh_gss_library *lib,
 234                                           Ssh_gss_ctx *ctx)
 235 {
 236     winSsh_gss_ctx *winctx = snew(winSsh_gss_ctx);
 237     memset(winctx, 0, sizeof(winSsh_gss_ctx));
 238
 239     /* prepare our "wrapper" structure */
 240     winctx->maj_stat =  winctx->min_stat = SEC_E_OK;
 241     winctx->context_handle = NULL;
 242
 243     /* Specifying no principal name here means use the credentials of
 244        the current logged-in user */
 245
 246     winctx->maj_stat = p_AcquireCredentialsHandleA(NULL,
 247                                                    "Kerberos",
 248                                                    SECPKG_CRED_OUTBOUND,
 249                                                    NULL,
 250                                                    NULL,
 251                                                    NULL,
 252                                                    NULL,
 253                                                    &winctx->cred_handle,
 254                                                    &winctx->expiry);
 255
 256     if (winctx->maj_stat != SEC_E_OK) return SSH_GSS_FAILURE;
 257
 258     *ctx = (Ssh_gss_ctx) winctx;
 259     return SSH_GSS_OK;
 260 }
 261
 262
 263 static Ssh_gss_stat ssh_sspi_init_sec_context(struct ssh_gss_library *lib,
 264                                               Ssh_gss_ctx *ctx,
 265                                               Ssh_gss_name srv_name,
 266                                               int to_deleg,
 267                                               Ssh_gss_buf *recv_tok,
 268                                               Ssh_gss_buf *send_tok)
 269 {
 270     winSsh_gss_ctx *winctx = (winSsh_gss_ctx *) *ctx;
 271     SecBuffer wsend_tok = {send_tok->length,SECBUFFER_TOKEN,send_tok->value};
 272     SecBuffer wrecv_tok = {recv_tok->length,SECBUFFER_TOKEN,recv_tok->value};
 273     SecBufferDesc output_desc={SECBUFFER_VERSION,1,&wsend_tok};
 274     SecBufferDesc input_desc ={SECBUFFER_VERSION,1,&wrecv_tok};
 275     unsigned long flags=ISC_REQ_MUTUAL_AUTH|ISC_REQ_REPLAY_DETECT|
 276         ISC_REQ_CONFIDENTIALITY|ISC_REQ_ALLOCATE_MEMORY;
 277     unsigned long ret_flags=0;
 278
 279     /* check if we have to delegate ... */
 280     if (to_deleg) flags |= ISC_REQ_DELEGATE;
 281     winctx->maj_stat = p_InitializeSecurityContextA(&winctx->cred_handle,
 282                                                     winctx->context_handle,
 283                                                     (char*) srv_name,
 284                                                     flags,
 285                                                     0,          /* reserved */
 286                                                     SECURITY_NATIVE_DREP,
 287                                                     &input_desc,
 288                                                     0,          /* reserved */
 289                                                     &winctx->context,
 290                                                     &output_desc,
 291                                                     &ret_flags,
 292                                                     &winctx->expiry);
 293
 294     /* prepare for the next round */
 295     winctx->context_handle = &winctx->context;
 296     send_tok->value = wsend_tok.pvBuffer;
 297     send_tok->length = wsend_tok.cbBuffer;
 298
 299     /* check & return our status */
 300     if (winctx->maj_stat==SEC_E_OK) return SSH_GSS_S_COMPLETE;
 301     if (winctx->maj_stat==SEC_I_CONTINUE_NEEDED) return SSH_GSS_S_CONTINUE_NEEDED;
 302
 303     return SSH_GSS_FAILURE;
 304 }
 305
 306 static Ssh_gss_stat ssh_sspi_free_tok(struct ssh_gss_library *lib,
 307                                       Ssh_gss_buf *send_tok)
 308 {
 309     /* check input */
 310     if (send_tok == NULL) return SSH_GSS_FAILURE;
 311
 312     /* free Windows buffer */
 313     p_FreeContextBuffer(send_tok->value);
 314     SSH_GSS_CLEAR_BUF(send_tok);
 315
 316     return SSH_GSS_OK;
 317 }
 318
 319 static Ssh_gss_stat ssh_sspi_release_cred(struct ssh_gss_library *lib,
 320                                           Ssh_gss_ctx *ctx)
 321 {
 322     winSsh_gss_ctx *winctx= (winSsh_gss_ctx *) *ctx;
 323
 324     /* check input */
 325     if (winctx == NULL) return SSH_GSS_FAILURE;
 326
 327     /* free Windows data */
 328     p_FreeCredentialsHandle(&winctx->cred_handle);
 329     p_DeleteSecurityContext(&winctx->context);
 330
 331     /* delete our "wrapper" structure */
 332     sfree(winctx);
 333     *ctx = (Ssh_gss_ctx) NULL;
 334
 335     return SSH_GSS_OK;
 336 }
 337
 338
 339 static Ssh_gss_stat ssh_sspi_release_name(struct ssh_gss_library *lib,
 340                                           Ssh_gss_name *srv_name)
 341 {
 342     char *pStr= (char *) *srv_name;
 343
 344     if (pStr == NULL) return SSH_GSS_FAILURE;
 345     sfree(pStr);
 346     *srv_name = (Ssh_gss_name) NULL;
 347
 348     return SSH_GSS_OK;
 349 }
 350
 351 static Ssh_gss_stat ssh_sspi_display_status(struct ssh_gss_library *lib,
 352                                             Ssh_gss_ctx ctx, Ssh_gss_buf *buf)
 353 {
 354     winSsh_gss_ctx *winctx = (winSsh_gss_ctx *) ctx;
 355     char *msg;
 356
 357     if (winctx == NULL) return SSH_GSS_FAILURE;
 358
 359     /* decode the error code */
 360     switch (winctx->maj_stat) {
 361       case SEC_E_OK: msg="SSPI status OK"; break;
 362       case SEC_E_INVALID_HANDLE: msg="The handle passed to the function"
 363             " is invalid.";
 364         break;
 365       case SEC_E_TARGET_UNKNOWN: msg="The target was not recognized."; break;
 366       case SEC_E_LOGON_DENIED: msg="The logon failed."; break;
 367       case SEC_E_INTERNAL_ERROR: msg="The Local Security Authority cannot"
 368             " be contacted.";
 369         break;
 370       case SEC_E_NO_CREDENTIALS: msg="No credentials are available in the"
 371             " security package.";
 372         break;
 373       case SEC_E_NO_AUTHENTICATING_AUTHORITY:
 374         msg="No authority could be contacted for authentication."
 375             "The domain name of the authenticating party could be wrong,"
 376             " the domain could be unreachable, or there might have been"
 377             " a trust relationship failure.";
 378         break;
 379       case SEC_E_INSUFFICIENT_MEMORY:
 380         msg="One or more of the SecBufferDesc structures passed as"
 381             " an OUT parameter has a buffer that is too small.";
 382         break;
 383       case SEC_E_INVALID_TOKEN:
 384         msg="The error is due to a malformed input token, such as a"
 385             " token corrupted in transit, a token"
 386             " of incorrect size, or a token passed into the wrong"
 387             " security package. Passing a token to"
 388             " the wrong package can happen if client and server did not"
 389             " negotiate the proper security package.";
 390         break;
 391       default:
 392         msg = "Internal SSPI error";
 393         break;
 394     }
 395
 396     buf->value = dupstr(msg);
 397     buf->length = strlen(buf->value);
 398
 399     return SSH_GSS_OK;
 400 }
 401
 402 static Ssh_gss_stat ssh_sspi_get_mic(struct ssh_gss_library *lib,
 403                                      Ssh_gss_ctx ctx, Ssh_gss_buf *buf,
 404                                      Ssh_gss_buf *hash)
 405 {
 406     winSsh_gss_ctx *winctx= (winSsh_gss_ctx *) ctx;
 407     SecPkgContext_Sizes ContextSizes;
 408     SecBufferDesc InputBufferDescriptor;
 409     SecBuffer InputSecurityToken[2];
 410
 411     if (winctx == NULL) return SSH_GSS_FAILURE;
 412
 413     winctx->maj_stat = 0;
 414
 415     memset(&ContextSizes, 0, sizeof(ContextSizes));
 416
 417     winctx->maj_stat = p_QueryContextAttributesA(&winctx->context,
 418                                                  SECPKG_ATTR_SIZES,
 419                                                  &ContextSizes);
 420
 421     if (winctx->maj_stat != SEC_E_OK ||
 422         ContextSizes.cbMaxSignature == 0)
 423         return winctx->maj_stat;
 424
 425     InputBufferDescriptor.cBuffers = 2;
 426     InputBufferDescriptor.pBuffers = InputSecurityToken;
 427     InputBufferDescriptor.ulVersion = SECBUFFER_VERSION;
 428     InputSecurityToken[0].BufferType = SECBUFFER_DATA;
 429     InputSecurityToken[0].cbBuffer = buf->length;
 430     InputSecurityToken[0].pvBuffer = buf->value;
 431     InputSecurityToken[1].BufferType = SECBUFFER_TOKEN;
 432     InputSecurityToken[1].cbBuffer = ContextSizes.cbMaxSignature;
 433     InputSecurityToken[1].pvBuffer = snewn(ContextSizes.cbMaxSignature, char);
 434
 435     winctx->maj_stat = p_MakeSignature(&winctx->context,
 436                                        0,
 437                                        &InputBufferDescriptor,
 438                                        0);
 439
 440     if (winctx->maj_stat == SEC_E_OK) {
 441         hash->length = InputSecurityToken[1].cbBuffer;
 442         hash->value = InputSecurityToken[1].pvBuffer;
 443     }
 444
 445     return winctx->maj_stat;
 446 }
 447
 448 static Ssh_gss_stat ssh_sspi_free_mic(struct ssh_gss_library *lib,
 449                                       Ssh_gss_buf *hash)
 450 {
 451     sfree(hash->value);
 452     return SSH_GSS_OK;
 453 }
 454
 455 static void ssh_sspi_bind_fns(struct ssh_gss_library *lib)
 456 {
 457     lib->indicate_mech = ssh_sspi_indicate_mech;
 458     lib->import_name = ssh_sspi_import_name;
 459     lib->release_name = ssh_sspi_release_name;
 460     lib->init_sec_context = ssh_sspi_init_sec_context;
 461     lib->free_tok = ssh_sspi_free_tok;
 462     lib->acquire_cred = ssh_sspi_acquire_cred;
 463     lib->release_cred = ssh_sspi_release_cred;
 464     lib->get_mic = ssh_sspi_get_mic;
 465     lib->free_mic = ssh_sspi_free_mic;
 466     lib->display_status = ssh_sspi_display_status;
 467 }
 468
 469 #else
 470
 471 /* Dummy function so this source file defines something if NO_GSSAPI
 472    is defined. */
 473
 474 void ssh_gss_init(void)
 475 {
 476 }
 477
 478 #endif