lib/gssapi/sanon/accept_sec_context.c

   1 /*
   2  * Copyright (c) 2019-2020, AuriStor, Inc.
   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  *
   9  * - Redistributions of source code must retain the above copyright
  10  *   notice, this list of conditions and the following disclaimer.
  11  *
  12  * - Redistributions in binary form must reproduce the above copyright
  13  *   notice, this list of conditions and the following disclaimer in
  14  *   the documentation and/or other materials provided with the
  15  *   distribution.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  18  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  19  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  20  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  21  * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
  22  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  23  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  24  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  26  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  27  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  28  * OF THE POSSIBILITY OF SUCH DAMAGE.
  29  *
  30  */
  31
  32 #include "sanon_locl.h"
  33
  34 OM_uint32 GSSAPI_CALLCONV
  35 _gss_sanon_accept_sec_context(OM_uint32 *minor,
  36                               gss_ctx_id_t *context_handle,
  37                               gss_const_cred_id_t verifier_cred_handle,
  38                               const gss_buffer_t input_token,
  39                               const gss_channel_bindings_t input_chan_bindings,
  40                               gss_name_t *src_name,
  41                               gss_OID *mech_type,
  42                               gss_buffer_t output_token,
  43                               OM_uint32 *ret_flags,
  44                               OM_uint32 *time_rec,
  45                               gss_cred_id_t *delegated_cred_handle)
  46 {
  47     static gss_buffer_desc empty = GSS_C_EMPTY_BUFFER;
  48     OM_uint32 major, tmp;
  49     sanon_ctx sc = (sanon_ctx)*context_handle;
  50     gss_buffer_desc mech_input_token = GSS_C_EMPTY_BUFFER;
  51     gss_buffer_desc initiator_pk = GSS_C_EMPTY_BUFFER;
  52     gss_buffer_desc hok_mic = GSS_C_EMPTY_BUFFER;
  53     gss_buffer_desc session_key = GSS_C_EMPTY_BUFFER;
  54     OM_uint32 req_flags = 0;
  55
  56     if (output_token == GSS_C_NO_BUFFER) {
  57         *minor = EINVAL;
  58         major = GSS_S_FAILURE;
  59         goto out;
  60     }
  61
  62     _mg_buffer_zero(output_token);
  63
  64     if (input_token == GSS_C_NO_BUFFER) {
  65         major = GSS_S_DEFECTIVE_TOKEN;
  66         goto out;
  67     } else if (sc != NULL) {
  68         major = GSS_S_BAD_STATUS;
  69         goto out;
  70     }
  71
  72     major = gss_decapsulate_token(input_token,
  73                                   GSS_SANON_X25519_MECHANISM,
  74                                   &mech_input_token);
  75     if (major != GSS_S_COMPLETE)
  76         goto out;
  77
  78     sc = calloc(1, sizeof(*sc));
  79     if (sc == NULL) {
  80         *minor = ENOMEM;
  81         major = GSS_S_FAILURE;
  82         goto out;
  83     }
  84
  85     /* initiator token can include optional 64-bit flags */
  86     if (mech_input_token.length != crypto_scalarmult_curve25519_BYTES &&
  87         mech_input_token.length != crypto_scalarmult_curve25519_BYTES + 8) {
  88         *minor = 0;
  89         major = GSS_S_DEFECTIVE_TOKEN;
  90         goto out;
  91     }
  92
  93     initiator_pk = mech_input_token;
  94     initiator_pk.length = crypto_scalarmult_curve25519_BYTES;
  95
  96     /* compute public and secret keys */
  97     major = _gss_sanon_curve25519_base(minor, sc);
  98     if (major != GSS_S_COMPLETE)
  99         goto out;
 100
 101     if (mech_input_token.length > crypto_scalarmult_curve25519_BYTES) {
 102         /* extra flags */
 103         uint8_t *p = (uint8_t *)mech_input_token.value + crypto_scalarmult_curve25519_BYTES;
 104         uint32_t dummy;
 105
 106         _gss_mg_decode_be_uint32(p, &dummy); /* upper 32 bits presently unused */
 107         _gss_mg_decode_be_uint32(&p[4], &req_flags);
 108     }
 109
 110     req_flags &= SANON_PROTOCOL_FLAG_MASK; /* do not let initiator set any other flags */
 111
 112     /* compute shared secret */
 113     major = _gss_sanon_curve25519(minor, sc, &initiator_pk, req_flags,
 114                                   input_chan_bindings, &session_key);
 115     if (major != GSS_S_COMPLETE)
 116         goto out;
 117
 118     req_flags |= GSS_C_REPLAY_FLAG | GSS_C_SEQUENCE_FLAG | GSS_C_CONF_FLAG |
 119         GSS_C_INTEG_FLAG | GSS_C_ANON_FLAG | GSS_C_TRANS_FLAG;
 120
 121     major = _gss_sanon_import_rfc4121_context(minor, sc, req_flags, &session_key);
 122     if (major != GSS_S_COMPLETE)
 123         goto out;
 124
 125     major = _gss_sanon_get_mic(minor, (gss_const_ctx_id_t)sc,
 126                                GSS_C_QOP_DEFAULT, &empty, &hok_mic);
 127     if (major != GSS_S_COMPLETE)
 128         goto out;
 129
 130     output_token->length = sizeof(sc->pk) + hok_mic.length;
 131     output_token->value = malloc(output_token->length);
 132     if (output_token->value == NULL) {
 133         output_token->length = 0;
 134         *minor = ENOMEM;
 135         major = GSS_S_FAILURE;
 136         goto out;
 137     }
 138
 139     memcpy(output_token->value, sc->pk, sizeof(sc->pk));
 140     memcpy((uint8_t *)output_token->value + sizeof(sc->pk), hok_mic.value, hok_mic.length);
 141
 142     major = GSS_S_COMPLETE;
 143
 144     *context_handle = (gss_ctx_id_t)sc;
 145
 146     if (src_name)
 147         *src_name = _gss_sanon_anonymous_identity;
 148     if (ret_flags)
 149         *ret_flags = req_flags;
 150     if (time_rec)
 151         *time_rec = GSS_C_INDEFINITE;
 152
 153 out:
 154     if (mech_type)
 155         *mech_type = GSS_SANON_X25519_MECHANISM;
 156     if (delegated_cred_handle)
 157         *delegated_cred_handle = GSS_C_NO_CREDENTIAL;
 158     if (GSS_ERROR(major)) {
 159         _gss_sanon_delete_sec_context(&tmp, (gss_ctx_id_t *)&sc, GSS_C_NO_BUFFER);
 160         *context_handle = GSS_C_NO_CONTEXT;
 161     }
 162     gss_release_buffer(&tmp, &mech_input_token);
 163     gss_release_buffer(&tmp, &hok_mic);
 164     _gss_secure_release_buffer(&tmp, &session_key);
 165
 166     return major;
 167 }