source4/heimdal/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 RCSID("$Id: gss_accept_sec_context.c 22071 2007-11-14 20:04:50Z lha $");
  31
  32 static OM_uint32
  33 parse_header(const gss_buffer_t input_token, gss_OID mech_oid)
  34 {
  35         unsigned char *p = input_token->value;
  36         size_t len = input_token->length;
  37         size_t a, b;
  38
  39         /*
  40          * Token must start with [APPLICATION 0] SEQUENCE.
  41          * But if it doesn't assume it is DCE-STYLE Kerberos!
  42          */
  43         if (len == 0)
  44                 return (GSS_S_DEFECTIVE_TOKEN);
  45
  46         p++;
  47         len--;
  48
  49         /*
  50          * Decode the length and make sure it agrees with the
  51          * token length.
  52          */
  53         if (len == 0)
  54                 return (GSS_S_DEFECTIVE_TOKEN);
  55         if ((*p & 0x80) == 0) {
  56                 a = *p;
  57                 p++;
  58                 len--;
  59         } else {
  60                 b = *p & 0x7f;
  61                 p++;
  62                 len--;
  63                 if (len < b)
  64                     return (GSS_S_DEFECTIVE_TOKEN);
  65                 a = 0;
  66                 while (b) {
  67                     a = (a << 8) | *p;
  68                     p++;
  69                     len--;
  70                     b--;
  71                 }
  72         }
  73         if (a != len)
  74                 return (GSS_S_DEFECTIVE_TOKEN);
  75
  76         /*
  77          * Decode the OID for the mechanism. Simplify life by
  78          * assuming that the OID length is less than 128 bytes.
  79          */
  80         if (len < 2 || *p != 0x06)
  81                 return (GSS_S_DEFECTIVE_TOKEN);
  82         if ((p[1] & 0x80) || p[1] > (len - 2))
  83                 return (GSS_S_DEFECTIVE_TOKEN);
  84         mech_oid->length = p[1];
  85         p += 2;
  86         len -= 2;
  87         mech_oid->elements = p;
  88
  89         return GSS_S_COMPLETE;
  90 }
  91
  92 static gss_OID_desc krb5_mechanism =
  93     {9, rk_UNCONST("\x2a\x86\x48\x86\xf7\x12\x01\x02\x02")};
  94 static gss_OID_desc ntlm_mechanism =
  95     {10, rk_UNCONST("\x2b\x06\x01\x04\x01\x82\x37\x02\x02\x0a")};
  96 static gss_OID_desc spnego_mechanism =
  97     {6, rk_UNCONST("\x2b\x06\x01\x05\x05\x02")};
  98
  99 static OM_uint32
 100 choose_mech(const gss_buffer_t input, gss_OID mech_oid)
 101 {
 102         OM_uint32 status;
 103
 104         /*
 105          * First try to parse the gssapi token header and see if it's a
 106          * correct header, use that in the first hand.
 107          */
 108
 109         status = parse_header(input, mech_oid);
 110         if (status == GSS_S_COMPLETE)
 111             return GSS_S_COMPLETE;
 112
 113         /*
 114          * Lets guess what mech is really is, callback function to mech ??
 115          */
 116
 117         if (input->length > 8 &&
 118             memcmp((const char *)input->value, "NTLMSSP\x00", 8) == 0)
 119         {
 120                 *mech_oid = ntlm_mechanism;
 121                 return GSS_S_COMPLETE;
 122         } else if (input->length != 0 &&
 123                    ((const char *)input->value)[0] == 0x6E)
 124         {
 125                 /* Could be a raw AP-REQ (check for APPLICATION tag) */
 126                 *mech_oid = krb5_mechanism;
 127                 return GSS_S_COMPLETE;
 128         } else if (input->length == 0) {
 129                 /*
 130                  * There is the a wierd mode of SPNEGO (in CIFS and
 131                  * SASL GSS-SPENGO where the first token is zero
 132                  * length and the acceptor returns a mech_list, lets
 133                  * hope that is what is happening now.
 134                  */
 135                 *mech_oid = spnego_mechanism;
 136                 return GSS_S_COMPLETE;
 137         }
 138         return status;
 139 }
 140
 141
 142 OM_uint32 gss_accept_sec_context(OM_uint32 *minor_status,
 143     gss_ctx_id_t *context_handle,
 144     const gss_cred_id_t acceptor_cred_handle,
 145     const gss_buffer_t input_token,
 146     const gss_channel_bindings_t input_chan_bindings,
 147     gss_name_t *src_name,
 148     gss_OID *mech_type,
 149     gss_buffer_t output_token,
 150     OM_uint32 *ret_flags,
 151     OM_uint32 *time_rec,
 152     gss_cred_id_t *delegated_cred_handle)
 153 {
 154         OM_uint32 major_status, mech_ret_flags;
 155         gssapi_mech_interface m;
 156         struct _gss_context *ctx = (struct _gss_context *) *context_handle;
 157         struct _gss_cred *cred = (struct _gss_cred *) acceptor_cred_handle;
 158         struct _gss_mechanism_cred *mc;
 159         gss_cred_id_t acceptor_mc, delegated_mc;
 160         gss_name_t src_mn;
 161         int allocated_ctx;
 162
 163         *minor_status = 0;
 164         if (src_name)
 165             *src_name = GSS_C_NO_NAME;
 166         if (mech_type)
 167             *mech_type = GSS_C_NO_OID;
 168         if (ret_flags)
 169             *ret_flags = 0;
 170         if (time_rec)
 171             *time_rec = 0;
 172         if (delegated_cred_handle)
 173             *delegated_cred_handle = GSS_C_NO_CREDENTIAL;
 174         _mg_buffer_zero(output_token);
 175
 176
 177         /*
 178          * If this is the first call (*context_handle is NULL), we must
 179          * parse the input token to figure out the mechanism to use.
 180          */
 181         if (*context_handle == GSS_C_NO_CONTEXT) {
 182                 gss_OID_desc mech_oid;
 183
 184                 major_status = choose_mech(input_token, &mech_oid);
 185                 if (major_status != GSS_S_COMPLETE)
 186                         return major_status;
 187
 188                 /*
 189                  * Now that we have a mechanism, we can find the
 190                  * implementation.
 191                  */
 192                 ctx = malloc(sizeof(struct _gss_context));
 193                 if (!ctx) {
 194                         *minor_status = ENOMEM;
 195                         return (GSS_S_DEFECTIVE_TOKEN);
 196                 }
 197                 memset(ctx, 0, sizeof(struct _gss_context));
 198                 m = ctx->gc_mech = __gss_get_mechanism(&mech_oid);
 199                 if (!m) {
 200                         free(ctx);
 201                         return (GSS_S_BAD_MECH);
 202                 }
 203                 allocated_ctx = 1;
 204         } else {
 205                 m = ctx->gc_mech;
 206                 allocated_ctx = 0;
 207         }
 208
 209         if (cred) {
 210                 SLIST_FOREACH(mc, &cred->gc_mc, gmc_link)
 211                         if (mc->gmc_mech == m)
 212                                 break;
 213                 if (!mc)
 214                         return (GSS_S_BAD_MECH);
 215                 acceptor_mc = mc->gmc_cred;
 216         } else {
 217                 acceptor_mc = GSS_C_NO_CREDENTIAL;
 218         }
 219         delegated_mc = GSS_C_NO_CREDENTIAL;
 220
 221         mech_ret_flags = 0;
 222         major_status = m->gm_accept_sec_context(minor_status,
 223             &ctx->gc_ctx,
 224             acceptor_mc,
 225             input_token,
 226             input_chan_bindings,
 227             &src_mn,
 228             mech_type,
 229             output_token,
 230             &mech_ret_flags,
 231             time_rec,
 232             &delegated_mc);
 233         if (major_status != GSS_S_COMPLETE &&
 234             major_status != GSS_S_CONTINUE_NEEDED)
 235         {
 236                 _gss_mg_error(m, major_status, *minor_status);
 237                 return (major_status);
 238         }
 239
 240         if (src_name && src_mn) {
 241                 /*
 242                  * Make a new name and mark it as an MN.
 243                  */
 244                 struct _gss_name *name = _gss_make_name(m, src_mn);
 245
 246                 if (!name) {
 247                         m->gm_release_name(minor_status, &src_mn);
 248                         return (GSS_S_FAILURE);
 249                 }
 250                 *src_name = (gss_name_t) name;
 251         } else if (src_mn) {
 252             m->gm_release_name(minor_status, &src_mn);
 253         }
 254
 255         if (mech_ret_flags & GSS_C_DELEG_FLAG) {
 256                 if (!delegated_cred_handle) {
 257                         m->gm_release_cred(minor_status, &delegated_mc);
 258                         *ret_flags &= ~GSS_C_DELEG_FLAG;
 259                 } else if (delegated_mc) {
 260                         struct _gss_cred *dcred;
 261                         struct _gss_mechanism_cred *dmc;
 262
 263                         dcred = malloc(sizeof(struct _gss_cred));
 264                         if (!dcred) {
 265                                 *minor_status = ENOMEM;
 266                                 return (GSS_S_FAILURE);
 267                         }
 268                         SLIST_INIT(&dcred->gc_mc);
 269                         dmc = malloc(sizeof(struct _gss_mechanism_cred));
 270                         if (!dmc) {
 271                                 free(dcred);
 272                                 *minor_status = ENOMEM;
 273                                 return (GSS_S_FAILURE);
 274                         }
 275                         dmc->gmc_mech = m;
 276                         dmc->gmc_mech_oid = &m->gm_mech_oid;
 277                         dmc->gmc_cred = delegated_mc;
 278                         SLIST_INSERT_HEAD(&dcred->gc_mc, dmc, gmc_link);
 279
 280                         *delegated_cred_handle = (gss_cred_id_t) dcred;
 281                 }
 282         }
 283
 284         if (ret_flags)
 285             *ret_flags = mech_ret_flags;
 286         *context_handle = (gss_ctx_id_t) ctx;
 287         return (major_status);
 288 }