lib/libgssapi/gss_accept_sec_context.c

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