lib/libgssapi/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  *      $FreeBSD$
  27  */
  28
  29 #include <gssapi/gssapi.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <errno.h>
  33
  34 #include "mech_switch.h"
  35 #include "context.h"
  36 #include "cred.h"
  37 #include "name.h"
  38 #include "utils.h"
  39
  40 static OM_uint32
  41 parse_header(const gss_buffer_t input_token, gss_OID mech_oid)
  42 {
  43         unsigned char *p = input_token->value;
  44         size_t len = input_token->length;
  45         size_t a, b;
  46
  47         /*
  48          * Token must start with [APPLICATION 0] SEQUENCE.
  49          * But if it doesn't assume it is DCE-STYLE Kerberos!
  50          */
  51         if (len == 0)
  52                 return (GSS_S_DEFECTIVE_TOKEN);
  53
  54         p++;
  55         len--;
  56
  57         /*
  58          * Decode the length and make sure it agrees with the
  59          * token length.
  60          */
  61         if (len == 0)
  62                 return (GSS_S_DEFECTIVE_TOKEN);
  63         if ((*p & 0x80) == 0) {
  64                 a = *p;
  65                 p++;
  66                 len--;
  67         } else {
  68                 b = *p & 0x7f;
  69                 p++;
  70                 len--;
  71                 if (len < b)
  72                     return (GSS_S_DEFECTIVE_TOKEN);
  73                 a = 0;
  74                 while (b) {
  75                     a = (a << 8) | *p;
  76                     p++;
  77                     len--;
  78                     b--;
  79                 }
  80         }
  81         if (a != len)
  82                 return (GSS_S_DEFECTIVE_TOKEN);
  83
  84         /*
  85          * Decode the OID for the mechanism. Simplify life by
  86          * assuming that the OID length is less than 128 bytes.
  87          */
  88         if (len < 2 || *p != 0x06)
  89                 return (GSS_S_DEFECTIVE_TOKEN);
  90         if ((p[1] & 0x80) || p[1] > (len - 2))
  91                 return (GSS_S_DEFECTIVE_TOKEN);
  92         mech_oid->length = p[1];
  93         p += 2;
  94         len -= 2;
  95         mech_oid->elements = p;
  96
  97         return (GSS_S_COMPLETE);
  98 }
  99
 100 static gss_OID_desc krb5_mechanism =
 101 {9, (void *)(uintptr_t) "\x2a\x86\x48\x86\xf7\x12\x01\x02\x02"};
 102 static gss_OID_desc ntlm_mechanism =
 103 {10, (void *)(uintptr_t) "\x2b\x06\x01\x04\x01\x82\x37\x02\x02\x0a"};
 104 static gss_OID_desc spnego_mechanism =
 105 {6, (void *)(uintptr_t) "\x2b\x06\x01\x05\x05\x02"};
 106
 107 static OM_uint32
 108 choose_mech(const gss_buffer_t input, gss_OID mech_oid)
 109 {
 110         OM_uint32 status;
 111
 112         /*
 113          * First try to parse the gssapi token header and see if it's a
 114          * correct header, use that in the first hand.
 115          */
 116
 117         status = parse_header(input, mech_oid);
 118         if (status == GSS_S_COMPLETE)
 119                 return (GSS_S_COMPLETE);
 120
 121         /*
 122          * Lets guess what mech is really is, callback function to mech ??
 123          */
 124
 125         if (input->length > 8 &&
 126             memcmp((const char *)input->value, "NTLMSSP\x00", 8) == 0)
 127         {
 128                 *mech_oid = ntlm_mechanism;
 129                 return (GSS_S_COMPLETE);
 130         } else if (input->length != 0 &&
 131             ((const char *)input->value)[0] == 0x6E)
 132         {
 133                 /* Could be a raw AP-REQ (check for APPLICATION tag) */
 134                 *mech_oid = krb5_mechanism;
 135                 return (GSS_S_COMPLETE);
 136         } else if (input->length == 0) {
 137                 /*
 138                  * There is the a weird mode of SPNEGO (in CIFS and
 139                  * SASL GSS-SPENGO where the first token is zero
 140                  * length and the acceptor returns a mech_list, lets
 141                  * hope that is what is happening now.
 142                  */
 143                 *mech_oid = spnego_mechanism;
 144                 return (GSS_S_COMPLETE);
 145         }
 146         return (status);
 147 }
 148
 149 OM_uint32 gss_accept_sec_context(OM_uint32 *minor_status,
 150     gss_ctx_id_t *context_handle,
 151     const gss_cred_id_t acceptor_cred_handle,
 152     const gss_buffer_t input_token,
 153     const gss_channel_bindings_t input_chan_bindings,
 154     gss_name_t *src_name,
 155     gss_OID *mech_type,
 156     gss_buffer_t output_token,
 157     OM_uint32 *ret_flags,
 158     OM_uint32 *time_rec,
 159     gss_cred_id_t *delegated_cred_handle)
 160 {
 161         OM_uint32 major_status, mech_ret_flags;
 162         struct _gss_mech_switch *m;
 163         struct _gss_context *ctx = (struct _gss_context *) *context_handle;
 164         struct _gss_cred *cred = (struct _gss_cred *) acceptor_cred_handle;
 165         struct _gss_mechanism_cred *mc;
 166         gss_cred_id_t acceptor_mc, delegated_mc;
 167         gss_name_t src_mn;
 168
 169         *minor_status = 0;
 170         if (src_name)
 171                 *src_name = GSS_C_NO_NAME;
 172         if (mech_type)
 173                 *mech_type = GSS_C_NO_OID;
 174         if (ret_flags)
 175                 *ret_flags = 0;
 176         if (time_rec)
 177                 *time_rec = 0;
 178         if (delegated_cred_handle)
 179                 *delegated_cred_handle = GSS_C_NO_CREDENTIAL;
 180         _gss_buffer_zero(output_token);
 181
 182         /*
 183          * If this is the first call (*context_handle is NULL), we must
 184          * parse the input token to figure out the mechanism to use.
 185          */
 186         if (*context_handle == GSS_C_NO_CONTEXT) {
 187                 gss_OID_desc mech_oid;
 188
 189                 major_status = choose_mech(input_token, &mech_oid);
 190                 if (major_status != GSS_S_COMPLETE)
 191                         return (major_status);
 192
 193                 /*
 194                  * Now that we have a mechanism, we can find the
 195                  * implementation.
 196                  */
 197                 ctx = malloc(sizeof(struct _gss_context));
 198                 if (!ctx) {
 199                         *minor_status = ENOMEM;
 200                         return (GSS_S_DEFECTIVE_TOKEN);
 201                 }
 202                 memset(ctx, 0, sizeof(struct _gss_context));
 203                 m = ctx->gc_mech = _gss_find_mech_switch(&mech_oid);
 204                 if (!m) {
 205                         free(ctx);
 206                         return (GSS_S_BAD_MECH);
 207                 }
 208         } else
 209                 m = ctx->gc_mech;
 210
 211         if (cred) {
 212                 SLIST_FOREACH(mc, &cred->gc_mc, gmc_link)
 213                         if (mc->gmc_mech == m)
 214                                 break;
 215                 if (!mc)
 216                         return (GSS_S_BAD_MECH);
 217                 acceptor_mc = mc->gmc_cred;
 218         } else {
 219                 acceptor_mc = GSS_C_NO_CREDENTIAL;
 220         }
 221         delegated_mc = GSS_C_NO_CREDENTIAL;
 222
 223         mech_ret_flags = 0;
 224         major_status = m->gm_accept_sec_context(minor_status,
 225             &ctx->gc_ctx,
 226             acceptor_mc,
 227             input_token,
 228             input_chan_bindings,
 229             &src_mn,
 230             mech_type,
 231             output_token,
 232             &mech_ret_flags,
 233             time_rec,
 234             &delegated_mc);
 235         if (major_status != GSS_S_COMPLETE &&
 236             major_status != GSS_S_CONTINUE_NEEDED) {
 237                 _gss_mg_error(m, major_status, *minor_status);
 238                 return (major_status);
 239         }
 240
 241         if (src_name && src_mn) {
 242                 /*
 243                  * Make a new name and mark it as an MN.
 244                  */
 245                 struct _gss_name *name = _gss_make_name(m, src_mn);
 246
 247                 if (!name) {
 248                         m->gm_release_name(minor_status, &src_mn);
 249                         return (GSS_S_FAILURE);
 250                 }
 251                 *src_name = (gss_name_t) name;
 252         } else if (src_mn) {
 253                 m->gm_release_name(minor_status, &src_mn);
 254         }
 255
 256         if (delegated_mc == GSS_C_NO_CREDENTIAL)
 257                 mech_ret_flags &= ~GSS_C_DELEG_FLAG;
 258
 259         if (mech_ret_flags & GSS_C_DELEG_FLAG) {
 260                 if (!delegated_cred_handle) {
 261                         m->gm_release_cred(minor_status, &delegated_mc);
 262                         mech_ret_flags &= ~GSS_C_DELEG_FLAG;
 263                 } else {
 264                         struct _gss_cred *dcred;
 265                         struct _gss_mechanism_cred *dmc;
 266
 267                         dcred = malloc(sizeof(struct _gss_cred));
 268                         if (!dcred) {
 269                                 *minor_status = ENOMEM;
 270                                 return (GSS_S_FAILURE);
 271                         }
 272                         SLIST_INIT(&dcred->gc_mc);
 273                         dmc = malloc(sizeof(struct _gss_mechanism_cred));
 274                         if (!dmc) {
 275                                 free(dcred);
 276                                 *minor_status = ENOMEM;
 277                                 return (GSS_S_FAILURE);
 278                         }
 279                         dmc->gmc_mech = m;
 280                         dmc->gmc_mech_oid = &m->gm_mech_oid;
 281                         dmc->gmc_cred = delegated_mc;
 282                         SLIST_INSERT_HEAD(&dcred->gc_mc, dmc, gmc_link);
 283
 284                         *delegated_cred_handle = (gss_cred_id_t) dcred;
 285                 }
 286         }
 287
 288         if (ret_flags)
 289                 *ret_flags = mech_ret_flags;
 290         *context_handle = (gss_ctx_id_t) ctx;
 291         return (major_status);
 292 }