crypto/openssh/gss-genr.c

   1 /* $OpenBSD: gss-genr.c,v 1.23 2015/01/20 23:14:00 deraadt Exp $ */
   2
   3 /*
   4  * Copyright (c) 2001-2007 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 <sys/types.h>
  32 #include <sys/param.h>
  33
  34 #include <limits.h>
  35 #include <stdarg.h>
  36 #include <string.h>
  37 #include <signal.h>
  38 #include <unistd.h>
  39
  40 #include "xmalloc.h"
  41 #include "buffer.h"
  42 #include "log.h"
  43 #include "ssh2.h"
  44
  45 #include "ssh-gss.h"
  46
  47 extern u_char *session_id2;
  48 extern u_int session_id2_len;
  49
  50 /* Check that the OID in a data stream matches that in the context */
  51 int
  52 ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len)
  53 {
  54         return (ctx != NULL && ctx->oid != GSS_C_NO_OID &&
  55             ctx->oid->length == len &&
  56             memcmp(ctx->oid->elements, data, len) == 0);
  57 }
  58
  59 /* Set the contexts OID from a data stream */
  60 void
  61 ssh_gssapi_set_oid_data(Gssctxt *ctx, void *data, size_t len)
  62 {
  63         if (ctx->oid != GSS_C_NO_OID) {
  64                 free(ctx->oid->elements);
  65                 free(ctx->oid);
  66         }
  67         ctx->oid = xcalloc(1, sizeof(gss_OID_desc));
  68         ctx->oid->length = len;
  69         ctx->oid->elements = xmalloc(len);
  70         memcpy(ctx->oid->elements, data, len);
  71 }
  72
  73 /* Set the contexts OID */
  74 void
  75 ssh_gssapi_set_oid(Gssctxt *ctx, gss_OID oid)
  76 {
  77         ssh_gssapi_set_oid_data(ctx, oid->elements, oid->length);
  78 }
  79
  80 /* All this effort to report an error ... */
  81 void
  82 ssh_gssapi_error(Gssctxt *ctxt)
  83 {
  84         char *s;
  85
  86         s = ssh_gssapi_last_error(ctxt, NULL, NULL);
  87         debug("%s", s);
  88         free(s);
  89 }
  90
  91 char *
  92 ssh_gssapi_last_error(Gssctxt *ctxt, OM_uint32 *major_status,
  93     OM_uint32 *minor_status)
  94 {
  95         OM_uint32 lmin;
  96         gss_buffer_desc msg = GSS_C_EMPTY_BUFFER;
  97         OM_uint32 ctx;
  98         Buffer b;
  99         char *ret;
 100
 101         buffer_init(&b);
 102
 103         if (major_status != NULL)
 104                 *major_status = ctxt->major;
 105         if (minor_status != NULL)
 106                 *minor_status = ctxt->minor;
 107
 108         ctx = 0;
 109         /* The GSSAPI error */
 110         do {
 111                 gss_display_status(&lmin, ctxt->major,
 112                     GSS_C_GSS_CODE, ctxt->oid, &ctx, &msg);
 113
 114                 buffer_append(&b, msg.value, msg.length);
 115                 buffer_put_char(&b, '\n');
 116
 117                 gss_release_buffer(&lmin, &msg);
 118         } while (ctx != 0);
 119
 120         /* The mechanism specific error */
 121         do {
 122                 gss_display_status(&lmin, ctxt->minor,
 123                     GSS_C_MECH_CODE, ctxt->oid, &ctx, &msg);
 124
 125                 buffer_append(&b, msg.value, msg.length);
 126                 buffer_put_char(&b, '\n');
 127
 128                 gss_release_buffer(&lmin, &msg);
 129         } while (ctx != 0);
 130
 131         buffer_put_char(&b, '\0');
 132         ret = xmalloc(buffer_len(&b));
 133         buffer_get(&b, ret, buffer_len(&b));
 134         buffer_free(&b);
 135         return (ret);
 136 }
 137
 138 /*
 139  * Initialise our GSSAPI context. We use this opaque structure to contain all
 140  * of the data which both the client and server need to persist across
 141  * {accept,init}_sec_context calls, so that when we do it from the userauth
 142  * stuff life is a little easier
 143  */
 144 void
 145 ssh_gssapi_build_ctx(Gssctxt **ctx)
 146 {
 147         *ctx = xcalloc(1, sizeof (Gssctxt));
 148         (*ctx)->context = GSS_C_NO_CONTEXT;
 149         (*ctx)->name = GSS_C_NO_NAME;
 150         (*ctx)->oid = GSS_C_NO_OID;
 151         (*ctx)->creds = GSS_C_NO_CREDENTIAL;
 152         (*ctx)->client = GSS_C_NO_NAME;
 153         (*ctx)->client_creds = GSS_C_NO_CREDENTIAL;
 154 }
 155
 156 /* Delete our context, providing it has been built correctly */
 157 void
 158 ssh_gssapi_delete_ctx(Gssctxt **ctx)
 159 {
 160         OM_uint32 ms;
 161
 162         if ((*ctx) == NULL)
 163                 return;
 164         if ((*ctx)->context != GSS_C_NO_CONTEXT)
 165                 gss_delete_sec_context(&ms, &(*ctx)->context, GSS_C_NO_BUFFER);
 166         if ((*ctx)->name != GSS_C_NO_NAME)
 167                 gss_release_name(&ms, &(*ctx)->name);
 168         if ((*ctx)->oid != GSS_C_NO_OID) {
 169                 free((*ctx)->oid->elements);
 170                 free((*ctx)->oid);
 171                 (*ctx)->oid = GSS_C_NO_OID;
 172         }
 173         if ((*ctx)->creds != GSS_C_NO_CREDENTIAL)
 174                 gss_release_cred(&ms, &(*ctx)->creds);
 175         if ((*ctx)->client != GSS_C_NO_NAME)
 176                 gss_release_name(&ms, &(*ctx)->client);
 177         if ((*ctx)->client_creds != GSS_C_NO_CREDENTIAL)
 178                 gss_release_cred(&ms, &(*ctx)->client_creds);
 179
 180         free(*ctx);
 181         *ctx = NULL;
 182 }
 183
 184 /*
 185  * Wrapper to init_sec_context
 186  * Requires that the context contains:
 187  *      oid
 188  *      server name (from ssh_gssapi_import_name)
 189  */
 190 OM_uint32
 191 ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok,
 192     gss_buffer_desc* send_tok, OM_uint32 *flags)
 193 {
 194         int deleg_flag = 0;
 195
 196         if (deleg_creds) {
 197                 deleg_flag = GSS_C_DELEG_FLAG;
 198                 debug("Delegating credentials");
 199         }
 200
 201         ctx->major = gss_init_sec_context(&ctx->minor,
 202             GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid,
 203             GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag,
 204             0, NULL, recv_tok, NULL, send_tok, flags, NULL);
 205
 206         if (GSS_ERROR(ctx->major))
 207                 ssh_gssapi_error(ctx);
 208
 209         return (ctx->major);
 210 }
 211
 212 /* Create a service name for the given host */
 213 OM_uint32
 214 ssh_gssapi_import_name(Gssctxt *ctx, const char *host)
 215 {
 216         gss_buffer_desc gssbuf;
 217         char *val;
 218
 219         xasprintf(&val, "host@%s", host);
 220         gssbuf.value = val;
 221         gssbuf.length = strlen(gssbuf.value);
 222
 223         if ((ctx->major = gss_import_name(&ctx->minor,
 224             &gssbuf, GSS_C_NT_HOSTBASED_SERVICE, &ctx->name)))
 225                 ssh_gssapi_error(ctx);
 226
 227         free(gssbuf.value);
 228         return (ctx->major);
 229 }
 230
 231 OM_uint32
 232 ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash)
 233 {
 234         if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context,
 235             GSS_C_QOP_DEFAULT, buffer, hash)))
 236                 ssh_gssapi_error(ctx);
 237
 238         return (ctx->major);
 239 }
 240
 241 void
 242 ssh_gssapi_buildmic(Buffer *b, const char *user, const char *service,
 243     const char *context)
 244 {
 245         buffer_init(b);
 246         buffer_put_string(b, session_id2, session_id2_len);
 247         buffer_put_char(b, SSH2_MSG_USERAUTH_REQUEST);
 248         buffer_put_cstring(b, user);
 249         buffer_put_cstring(b, service);
 250         buffer_put_cstring(b, context);
 251 }
 252
 253 int
 254 ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host)
 255 {
 256         gss_buffer_desc token = GSS_C_EMPTY_BUFFER;
 257         OM_uint32 major, minor;
 258         gss_OID_desc spnego_oid = {6, (void *)"\x2B\x06\x01\x05\x05\x02"};
 259
 260         /* RFC 4462 says we MUST NOT do SPNEGO */
 261         if (oid->length == spnego_oid.length &&
 262             (memcmp(oid->elements, spnego_oid.elements, oid->length) == 0))
 263                 return 0; /* false */
 264
 265         ssh_gssapi_build_ctx(ctx);
 266         ssh_gssapi_set_oid(*ctx, oid);
 267         major = ssh_gssapi_import_name(*ctx, host);
 268         if (!GSS_ERROR(major)) {
 269                 major = ssh_gssapi_init_ctx(*ctx, 0, GSS_C_NO_BUFFER, &token,
 270                     NULL);
 271                 gss_release_buffer(&minor, &token);
 272                 if ((*ctx)->context != GSS_C_NO_CONTEXT)
 273                         gss_delete_sec_context(&minor, &(*ctx)->context,
 274                             GSS_C_NO_BUFFER);
 275         }
 276
 277         if (GSS_ERROR(major))
 278                 ssh_gssapi_delete_ctx(ctx);
 279
 280         return (!GSS_ERROR(major));
 281 }
 282
 283 #endif /* GSSAPI */