gss-genr.c

   1 /* $OpenBSD: gss-genr.c,v 1.11 2006/07/22 20:48:23 stevesk Exp $ */
   2
   3 /*
   4  * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include "includes.h"
  28
  29 #ifdef GSSAPI
  30
  31 #include <string.h>
  32 #include <unistd.h>
  33
  34 #include "xmalloc.h"
  35 #include "bufaux.h"
  36 #include "log.h"
  37 #include "ssh2.h"
  38
  39 #include "ssh-gss.h"
  40
  41 extern u_char *session_id2;
  42 extern u_int session_id2_len;
  43
  44 /* Check that the OID in a data stream matches that in the context */
  45 int
  46 ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len)
  47 {
  48         return (ctx != NULL && ctx->oid != GSS_C_NO_OID &&
  49             ctx->oid->length == len &&
  50             memcmp(ctx->oid->elements, data, len) == 0);
  51 }
  52
  53 /* Set the contexts OID from a data stream */
  54 void
  55 ssh_gssapi_set_oid_data(Gssctxt *ctx, void *data, size_t len)
  56 {
  57         if (ctx->oid != GSS_C_NO_OID) {
  58                 xfree(ctx->oid->elements);
  59                 xfree(ctx->oid);
  60         }
  61         ctx->oid = xmalloc(sizeof(gss_OID_desc));
  62         ctx->oid->length = len;
  63         ctx->oid->elements = xmalloc(len);
  64         memcpy(ctx->oid->elements, data, len);
  65 }
  66
  67 /* Set the contexts OID */
  68 void
  69 ssh_gssapi_set_oid(Gssctxt *ctx, gss_OID oid)
  70 {
  71         ssh_gssapi_set_oid_data(ctx, oid->elements, oid->length);
  72 }
  73
  74 /* All this effort to report an error ... */
  75 void
  76 ssh_gssapi_error(Gssctxt *ctxt)
  77 {
  78         char *s;
  79
  80         s = ssh_gssapi_last_error(ctxt, NULL, NULL);
  81         debug("%s", s);
  82         xfree(s);
  83 }
  84
  85 char *
  86 ssh_gssapi_last_error(Gssctxt *ctxt, OM_uint32 *major_status,
  87     OM_uint32 *minor_status)
  88 {
  89         OM_uint32 lmin;
  90         gss_buffer_desc msg = GSS_C_EMPTY_BUFFER;
  91         OM_uint32 ctx;
  92         Buffer b;
  93         char *ret;
  94
  95         buffer_init(&b);
  96
  97         if (major_status != NULL)
  98                 *major_status = ctxt->major;
  99         if (minor_status != NULL)
 100                 *minor_status = ctxt->minor;
 101
 102         ctx = 0;
 103         /* The GSSAPI error */
 104         do {
 105                 gss_display_status(&lmin, ctxt->major,
 106                     GSS_C_GSS_CODE, GSS_C_NULL_OID, &ctx, &msg);
 107
 108                 buffer_append(&b, msg.value, msg.length);
 109                 buffer_put_char(&b, '\n');
 110
 111                 gss_release_buffer(&lmin, &msg);
 112         } while (ctx != 0);
 113
 114         /* The mechanism specific error */
 115         do {
 116                 gss_display_status(&lmin, ctxt->minor,
 117                     GSS_C_MECH_CODE, GSS_C_NULL_OID, &ctx, &msg);
 118
 119                 buffer_append(&b, msg.value, msg.length);
 120                 buffer_put_char(&b, '\n');
 121
 122                 gss_release_buffer(&lmin, &msg);
 123         } while (ctx != 0);
 124
 125         buffer_put_char(&b, '\0');
 126         ret = xmalloc(buffer_len(&b));
 127         buffer_get(&b, ret, buffer_len(&b));
 128         buffer_free(&b);
 129         return (ret);
 130 }
 131
 132 /*
 133  * Initialise our GSSAPI context. We use this opaque structure to contain all
 134  * of the data which both the client and server need to persist across
 135  * {accept,init}_sec_context calls, so that when we do it from the userauth
 136  * stuff life is a little easier
 137  */
 138 void
 139 ssh_gssapi_build_ctx(Gssctxt **ctx)
 140 {
 141         *ctx = xcalloc(1, sizeof (Gssctxt));
 142         (*ctx)->context = GSS_C_NO_CONTEXT;
 143         (*ctx)->name = GSS_C_NO_NAME;
 144         (*ctx)->oid = GSS_C_NO_OID;
 145         (*ctx)->creds = GSS_C_NO_CREDENTIAL;
 146         (*ctx)->client = GSS_C_NO_NAME;
 147         (*ctx)->client_creds = GSS_C_NO_CREDENTIAL;
 148 }
 149
 150 /* Delete our context, providing it has been built correctly */
 151 void
 152 ssh_gssapi_delete_ctx(Gssctxt **ctx)
 153 {
 154         OM_uint32 ms;
 155
 156         if ((*ctx) == NULL)
 157                 return;
 158         if ((*ctx)->context != GSS_C_NO_CONTEXT)
 159                 gss_delete_sec_context(&ms, &(*ctx)->context, GSS_C_NO_BUFFER);
 160         if ((*ctx)->name != GSS_C_NO_NAME)
 161                 gss_release_name(&ms, &(*ctx)->name);
 162         if ((*ctx)->oid != GSS_C_NO_OID) {
 163                 xfree((*ctx)->oid->elements);
 164                 xfree((*ctx)->oid);
 165                 (*ctx)->oid = GSS_C_NO_OID;
 166         }
 167         if ((*ctx)->creds != GSS_C_NO_CREDENTIAL)
 168                 gss_release_cred(&ms, &(*ctx)->creds);
 169         if ((*ctx)->client != GSS_C_NO_NAME)
 170                 gss_release_name(&ms, &(*ctx)->client);
 171         if ((*ctx)->client_creds != GSS_C_NO_CREDENTIAL)
 172                 gss_release_cred(&ms, &(*ctx)->client_creds);
 173
 174         xfree(*ctx);
 175         *ctx = NULL;
 176 }
 177
 178 /*
 179  * Wrapper to init_sec_context
 180  * Requires that the context contains:
 181  *      oid
 182  *      server name (from ssh_gssapi_import_name)
 183  */
 184 OM_uint32
 185 ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok,
 186     gss_buffer_desc* send_tok, OM_uint32 *flags)
 187 {
 188         int deleg_flag = 0;
 189
 190         if (deleg_creds) {
 191                 deleg_flag = GSS_C_DELEG_FLAG;
 192                 debug("Delegating credentials");
 193         }
 194
 195         ctx->major = gss_init_sec_context(&ctx->minor,
 196             GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid,
 197             GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag,
 198             0, NULL, recv_tok, NULL, send_tok, flags, NULL);
 199
 200         if (GSS_ERROR(ctx->major))
 201                 ssh_gssapi_error(ctx);
 202
 203         return (ctx->major);
 204 }
 205
 206 /* Create a service name for the given host */
 207 OM_uint32
 208 ssh_gssapi_import_name(Gssctxt *ctx, const char *host)
 209 {
 210         gss_buffer_desc gssbuf;
 211         char *val;
 212
 213         xasprintf(&val, "host@%s", host);
 214         gssbuf.value = val;
 215         gssbuf.length = strlen(gssbuf.value);
 216
 217         if ((ctx->major = gss_import_name(&ctx->minor,
 218             &gssbuf, GSS_C_NT_HOSTBASED_SERVICE, &ctx->name)))
 219                 ssh_gssapi_error(ctx);
 220
 221         xfree(gssbuf.value);
 222         return (ctx->major);
 223 }
 224
 225 /* Acquire credentials for a server running on the current host.
 226  * Requires that the context structure contains a valid OID
 227  */
 228
 229 /* Returns a GSSAPI error code */
 230 OM_uint32
 231 ssh_gssapi_acquire_cred(Gssctxt *ctx)
 232 {
 233         OM_uint32 status;
 234         char lname[MAXHOSTNAMELEN];
 235         gss_OID_set oidset;
 236
 237         gss_create_empty_oid_set(&status, &oidset);
 238         gss_add_oid_set_member(&status, ctx->oid, &oidset);
 239
 240         if (gethostname(lname, MAXHOSTNAMELEN)) {
 241                 gss_release_oid_set(&status, &oidset);
 242                 return (-1);
 243         }
 244
 245         if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) {
 246                 gss_release_oid_set(&status, &oidset);
 247                 return (ctx->major);
 248         }
 249
 250         if ((ctx->major = gss_acquire_cred(&ctx->minor,
 251             ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds, NULL, NULL)))
 252                 ssh_gssapi_error(ctx);
 253
 254         gss_release_oid_set(&status, &oidset);
 255         return (ctx->major);
 256 }
 257
 258 OM_uint32
 259 ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash)
 260 {
 261         if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context,
 262             GSS_C_QOP_DEFAULT, buffer, hash)))
 263                 ssh_gssapi_error(ctx);
 264
 265         return (ctx->major);
 266 }
 267
 268 void
 269 ssh_gssapi_buildmic(Buffer *b, const char *user, const char *service,
 270     const char *context)
 271 {
 272         buffer_init(b);
 273         buffer_put_string(b, session_id2, session_id2_len);
 274         buffer_put_char(b, SSH2_MSG_USERAUTH_REQUEST);
 275         buffer_put_cstring(b, user);
 276         buffer_put_cstring(b, service);
 277         buffer_put_cstring(b, context);
 278 }
 279
 280 OM_uint32
 281 ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid)
 282 {
 283         if (*ctx)
 284                 ssh_gssapi_delete_ctx(ctx);
 285         ssh_gssapi_build_ctx(ctx);
 286         ssh_gssapi_set_oid(*ctx, oid);
 287         return (ssh_gssapi_acquire_cred(*ctx));
 288 }
 289
 290 #endif /* GSSAPI */