lib/gssapi/mech/gss_accept_sec_context.c

   1 /*-
   2  * Copyright (c) 2005 Doug Rabson
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  *      $FreeBSD: src/lib/libgssapi/gss_accept_sec_context.c,v 1.1 2005/12/29 14:40:20 dfr Exp $
  27  */
  28
  29 #include "mech_locl.h"
  30
  31 static OM_uint32
  32 parse_header(const gss_buffer_t input_token, gss_OID mech_oid)
  33 {
  34         unsigned char *p = input_token->value;
  35         size_t len = input_token->length;
  36         size_t a, b;
  37
  38         /*
  39          * Token must start with [APPLICATION 0] SEQUENCE.
  40          * But if it doesn't assume it is DCE-STYLE Kerberos!
  41          */
  42         if (len == 0)
  43                 return (GSS_S_DEFECTIVE_TOKEN);
  44
  45         p++;
  46         len--;
  47
  48         /*
  49          * Decode the length and make sure it agrees with the
  50          * token length.
  51          */
  52         if (len == 0)
  53                 return (GSS_S_DEFECTIVE_TOKEN);
  54         if ((*p & 0x80) == 0) {
  55                 a = *p;
  56                 p++;
  57                 len--;
  58         } else {
  59                 b = *p & 0x7f;
  60                 p++;
  61                 len--;
  62                 if (len < b)
  63                     return (GSS_S_DEFECTIVE_TOKEN);
  64                 a = 0;
  65                 while (b) {
  66                     a = (a << 8) | *p;
  67                     p++;
  68                     len--;
  69                     b--;
  70                 }
  71         }
  72         if (a != len)
  73                 return (GSS_S_DEFECTIVE_TOKEN);
  74
  75         /*
  76          * Decode the OID for the mechanism. Simplify life by
  77          * assuming that the OID length is less than 128 bytes.
  78          */
  79         if (len < 2 || *p != 0x06)
  80                 return (GSS_S_DEFECTIVE_TOKEN);
  81         if ((p[1] & 0x80) || p[1] > (len - 2))
  82                 return (GSS_S_DEFECTIVE_TOKEN);
  83         mech_oid->length = p[1];
  84         p += 2;
  85         len -= 2;
  86         mech_oid->elements = p;
  87
  88         return GSS_S_COMPLETE;
  89 }
  90
  91 static gss_OID_desc krb5_mechanism =
  92     {9, rk_UNCONST("\x2a\x86\x48\x86\xf7\x12\x01\x02\x02")};
  93 static gss_OID_desc ntlm_mechanism =
  94     {10, rk_UNCONST("\x2b\x06\x01\x04\x01\x82\x37\x02\x02\x0a")};
  95 static gss_OID_desc spnego_mechanism =
  96     {6, rk_UNCONST("\x2b\x06\x01\x05\x05\x02")};
  97
  98 static OM_uint32
  99 choose_mech(const gss_buffer_t input, gss_OID mech_oid)
 100 {
 101         OM_uint32 status;
 102
 103         /*
 104          * First try to parse the gssapi token header and see if it's a
 105          * correct header, use that in the first hand.
 106          */
 107
 108         status = parse_header(input, mech_oid);
 109         if (status == GSS_S_COMPLETE)
 110             return GSS_S_COMPLETE;
 111
 112         /*
 113          * Lets guess what mech is really is, callback function to mech ??
 114          */
 115
 116         if (input->length > 8 &&
 117             memcmp((const char *)input->value, "NTLMSSP\x00", 8) == 0)
 118         {
 119                 *mech_oid = ntlm_mechanism;
 120                 return GSS_S_COMPLETE;
 121         } else if (input->length != 0 &&
 122                    ((const char *)input->value)[0] == 0x6E)
 123         {
 124                 /* Could be a raw AP-REQ (check for APPLICATION tag) */
 125                 *mech_oid = krb5_mechanism;
 126                 return GSS_S_COMPLETE;
 127         } else if (input->length == 0) {
 128                 /*
 129                  * There is the a wierd mode of SPNEGO (in CIFS and
 130                  * SASL GSS-SPENGO where the first token is zero
 131                  * length and the acceptor returns a mech_list, lets
 132                  * hope that is what is happening now.
 133                  *
 134                  * http://msdn.microsoft.com/en-us/library/cc213114.aspx
 135                  * "NegTokenInit2 Variation for Server-Initiation"
 136                  */
 137                 *mech_oid = spnego_mechanism;
 138                 return GSS_S_COMPLETE;
 139         }
 140         return status;
 141 }
 142
 143
 144 OM_uint32 gss_accept_sec_context(OM_uint32 *minor_status,
 145     gss_ctx_id_t *context_handle,
 146     const gss_cred_id_t acceptor_cred_handle,
 147     const gss_buffer_t input_token,
 148     const gss_channel_bindings_t input_chan_bindings,
 149     gss_name_t *src_name,
 150     gss_OID *mech_type,
 151     gss_buffer_t output_token,
 152     OM_uint32 *ret_flags,
 153     OM_uint32 *time_rec,
 154     gss_cred_id_t *delegated_cred_handle)
 155 {
 156         OM_uint32 major_status, mech_ret_flags, junk;
 157         gssapi_mech_interface m;
 158         struct _gss_context *ctx = (struct _gss_context *) *context_handle;
 159         struct _gss_cred *cred = (struct _gss_cred *) acceptor_cred_handle;
 160         struct _gss_mechanism_cred *mc;
 161         gss_cred_id_t acceptor_mc, delegated_mc;
 162         gss_name_t src_mn;
 163         gss_OID mech_ret_type = NULL;
 164
 165         *minor_status = 0;
 166         if (src_name)
 167             *src_name = GSS_C_NO_NAME;
 168         if (mech_type)
 169             *mech_type = GSS_C_NO_OID;
 170         if (ret_flags)
 171             *ret_flags = 0;
 172         if (time_rec)
 173             *time_rec = 0;
 174         if (delegated_cred_handle)
 175             *delegated_cred_handle = GSS_C_NO_CREDENTIAL;
 176         _mg_buffer_zero(output_token);
 177
 178
 179         /*
 180          * If this is the first call (*context_handle is NULL), we must
 181          * parse the input token to figure out the mechanism to use.
 182          */
 183         if (*context_handle == GSS_C_NO_CONTEXT) {
 184                 gss_OID_desc mech_oid;
 185
 186                 major_status = choose_mech(input_token, &mech_oid);
 187                 if (major_status != GSS_S_COMPLETE)
 188                         return major_status;
 189
 190                 /*
 191                  * Now that we have a mechanism, we can find the
 192                  * implementation.
 193                  */
 194                 ctx = malloc(sizeof(struct _gss_context));
 195                 if (!ctx) {
 196                         *minor_status = ENOMEM;
 197                         return (GSS_S_DEFECTIVE_TOKEN);
 198                 }
 199                 memset(ctx, 0, sizeof(struct _gss_context));
 200                 m = ctx->gc_mech = __gss_get_mechanism(&mech_oid);
 201                 if (!m) {
 202                         free(ctx);
 203                         return (GSS_S_BAD_MECH);
 204                 }
 205                 *context_handle = (gss_ctx_id_t) ctx;
 206         } else {
 207                 m = ctx->gc_mech;
 208         }
 209
 210         if (cred) {
 211                 SLIST_FOREACH(mc, &cred->gc_mc, gmc_link)
 212                         if (mc->gmc_mech == m)
 213                                 break;
 214                 if (!mc) {
 215                         gss_delete_sec_context(&junk, context_handle, NULL);
 216                         return (GSS_S_BAD_MECH);
 217                 }
 218                 acceptor_mc = mc->gmc_cred;
 219         } else {
 220                 acceptor_mc = GSS_C_NO_CREDENTIAL;
 221         }
 222         delegated_mc = GSS_C_NO_CREDENTIAL;
 223
 224         mech_ret_flags = 0;
 225         major_status = m->gm_accept_sec_context(minor_status,
 226             &ctx->gc_ctx,
 227             acceptor_mc,
 228             input_token,
 229             input_chan_bindings,
 230             &src_mn,
 231             &mech_ret_type,
 232             output_token,
 233             &mech_ret_flags,
 234             time_rec,
 235             &delegated_mc);
 236         if (major_status != GSS_S_COMPLETE &&
 237             major_status != GSS_S_CONTINUE_NEEDED)
 238         {
 239                 _gss_mg_error(m, major_status, *minor_status);
 240                 gss_delete_sec_context(&junk, context_handle, NULL);
 241                 return (major_status);
 242         }
 243
 244         if (mech_type)
 245             *mech_type = mech_ret_type;
 246
 247         if (src_name && src_mn) {
 248                 /*
 249                  * Make a new name and mark it as an MN.
 250                  */
 251                 struct _gss_name *name = _gss_make_name(m, src_mn);
 252
 253                 if (!name) {
 254                         m->gm_release_name(minor_status, &src_mn);
 255                         gss_delete_sec_context(&junk, context_handle, NULL);
 256                         return (GSS_S_FAILURE);
 257                 }
 258                 *src_name = (gss_name_t) name;
 259         } else if (src_mn) {
 260                 m->gm_release_name(minor_status, &src_mn);
 261         }
 262
 263         if (mech_ret_flags & GSS_C_DELEG_FLAG) {
 264                 if (!delegated_cred_handle) {
 265                         m->gm_release_cred(minor_status, &delegated_mc);
 266                         if (ret_flags)
 267                                 *ret_flags &= ~GSS_C_DELEG_FLAG;
 268                 } else if (gss_oid_equal(mech_ret_type, &m->gm_mech_oid) == 0) {
 269                         /*
 270                          * If the returned mech_type is not the same
 271                          * as the mech, assume its pseudo mech type
 272                          * and the returned type is already a
 273                          * mech-glue object
 274                          */
 275                         *delegated_cred_handle = delegated_mc;
 276
 277                 } else if (delegated_mc) {
 278                         struct _gss_cred *dcred;
 279                         struct _gss_mechanism_cred *dmc;
 280
 281                         dcred = malloc(sizeof(struct _gss_cred));
 282                         if (!dcred) {
 283                                 *minor_status = ENOMEM;
 284                                 gss_delete_sec_context(&junk, context_handle, NULL);
 285                                 return (GSS_S_FAILURE);
 286                         }
 287                         SLIST_INIT(&dcred->gc_mc);
 288                         dmc = malloc(sizeof(struct _gss_mechanism_cred));
 289                         if (!dmc) {
 290                                 free(dcred);
 291                                 *minor_status = ENOMEM;
 292                                 gss_delete_sec_context(&junk, context_handle, NULL);
 293                                 return (GSS_S_FAILURE);
 294                         }
 295                         dmc->gmc_mech = m;
 296                         dmc->gmc_mech_oid = &m->gm_mech_oid;
 297                         dmc->gmc_cred = delegated_mc;
 298                         SLIST_INSERT_HEAD(&dcred->gc_mc, dmc, gmc_link);
 299
 300                         *delegated_cred_handle = (gss_cred_id_t) dcred;
 301                 }
 302         }
 303
 304         if (ret_flags)
 305             *ret_flags = mech_ret_flags;
 306         return (major_status);
 307 }