aboutsummaryrefslogtreecommitdiffstats
path: root/src/kdc/kdc_preauth_encts.c
blob: 25fc784576efc3e8c1003035ef9ada148f1ad867 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* kdc/kdc_preauth_encts.c - Encrypted timestamp kdcpreauth module */
/*
 * Copyright (C) 1995, 2003, 2007, 2011 by the Massachusetts Institute of Technology.
 * All rights reserved.
 *
 * Export of this software from the United States of America may
 *   require a specific license from the United States Government.
 *   It is the responsibility of any person or organization contemplating
 *   export to obtain such a license before exporting.
 *
 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
 * distribute this software and its documentation for any purpose and
 * without fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright notice and
 * this permission notice appear in supporting documentation, and that
 * the name of M.I.T. not be used in advertising or publicity pertaining
 * to distribution of the software without specific, written prior
 * permission.  Furthermore if you modify this software you must label
 * your software as modified software and not distribute it in such a
 * fashion that it might be confused with the original M.I.T. software.
 * M.I.T. makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is" without express
 * or implied warranty.
 */

#include <k5-int.h>
#include <krb5/kdcpreauth_plugin.h>
#include "kdc_util.h"

static void
enc_ts_get(krb5_context context, krb5_kdc_req *request,
           krb5_kdcpreauth_callbacks cb, krb5_kdcpreauth_rock rock,
           krb5_kdcpreauth_moddata moddata, krb5_preauthtype pa_type,
           krb5_kdcpreauth_edata_respond_fn respond, void *arg)
{
    krb5_keyblock *armor_key = cb->fast_armor(context, rock);

    /* Encrypted timestamp must not be used with FAST, and requires a key. */
    if (armor_key != NULL || !cb->have_client_keys(context, rock))
        (*respond)(arg, ENOENT, NULL);
    else
        (*respond)(arg, 0, NULL);
}

static void
enc_ts_verify(krb5_context context, krb5_data *req_pkt, krb5_kdc_req *request,
              krb5_enc_tkt_part *enc_tkt_reply, krb5_pa_data *pa,
              krb5_kdcpreauth_callbacks cb, krb5_kdcpreauth_rock rock,
              krb5_kdcpreauth_moddata moddata,
              krb5_kdcpreauth_verify_respond_fn respond, void *arg)
{
    krb5_pa_enc_ts *            pa_enc = 0;
    krb5_error_code             retval;
    krb5_data                   scratch;
    krb5_data                   enc_ts_data;
    krb5_enc_data               *enc_data = 0;
    krb5_keyblock               key;
    krb5_key_data *             client_key;
    krb5_int32                  start;

    scratch.data = (char *)pa->contents;
    scratch.length = pa->length;

    enc_ts_data.data = 0;

    if ((retval = decode_krb5_enc_data(&scratch, &enc_data)) != 0)
        goto cleanup;

    enc_ts_data.length = enc_data->ciphertext.length;
    if ((enc_ts_data.data = (char *) malloc(enc_ts_data.length)) == NULL)
        goto cleanup;

    start = 0;
    while (1) {
        if ((retval = krb5_dbe_search_enctype(context, rock->client,
                                              &start, enc_data->enctype,
                                              -1, 0, &client_key)))
            goto cleanup;

        if ((retval = krb5_dbe_decrypt_key_data(context, NULL, client_key,
                                                &key, NULL)))
            goto cleanup;

        key.enctype = enc_data->enctype;

        retval = krb5_c_decrypt(context, &key, KRB5_KEYUSAGE_AS_REQ_PA_ENC_TS,
                                0, enc_data, &enc_ts_data);
        krb5_free_keyblock_contents(context, &key);
        if (retval == 0)
            break;
    }

    if ((retval = decode_krb5_pa_enc_ts(&enc_ts_data, &pa_enc)) != 0)
        goto cleanup;

    retval = krb5_check_clockskew(context, pa_enc->patimestamp);
    if (retval)
        goto cleanup;

    setflag(enc_tkt_reply->flags, TKT_FLG_PRE_AUTH);

    retval = 0;

cleanup:
    if (enc_data) {
        krb5_free_data_contents(context, &enc_data->ciphertext);
        free(enc_data);
    }
    krb5_free_data_contents(context, &enc_ts_data);
    if (pa_enc)
        free(pa_enc);
    /* If we get NO_MATCHING_KEY, it probably means that the password was
     * incorrect. */
    if (retval == KRB5_KDB_NO_MATCHING_KEY)
        retval = KRB5KDC_ERR_PREAUTH_FAILED;

    (*respond)(arg, retval, NULL, NULL, NULL);
}

static krb5_preauthtype enc_ts_types[] = {
    KRB5_PADATA_ENC_TIMESTAMP, 0 };

krb5_error_code
kdcpreauth_encrypted_timestamp_initvt(krb5_context context, int maj_ver,
                                      int min_ver, krb5_plugin_vtable vtable)
{
    krb5_kdcpreauth_vtable vt;

    if (maj_ver != 1)
        return KRB5_PLUGIN_VER_NOTSUPP;
    vt = (krb5_kdcpreauth_vtable)vtable;
    vt->name = "encrypted_timestamp";
    vt->pa_type_list = enc_ts_types;
    vt->edata = enc_ts_get;
    vt->verify = enc_ts_verify;
    return 0;
}