1/*
2 * $Id: uams_pgp.c,v 1.12 2009-10-15 11:39:48 didg Exp $
3 *
4 * Copyright (c) 1990,1993 Regents of The University of Michigan.
5 * Copyright (c) 1999 Adrian Sun (asun@u.washington.edu)
6 * All Rights Reserved.  See COPYRIGHT.
7 */
8
9#ifdef HAVE_CONFIG_H
10#include "config.h"
11#endif /* HAVE_CONFIG_H */
12
13#ifdef UAM_PGP
14
15#include <atalk/standards.h>
16
17#include <stdio.h>
18#include <stdlib.h>
19#include <string.h>
20#ifdef HAVE_UNISTD_H
21#include <unistd.h>
22#endif /* HAVE_UNISTD_H */
23#ifdef HAVE_CRYPT_H
24#include <crypt.h>
25#endif /* HAVE_CRYPT_H */
26#include <pwd.h>
27#include <atalk/logger.h>
28
29#if defined(GNUTLS_DHX)
30#include <gnutls/openssl.h>
31#elif defined(OPENSSL_DHX)
32#include <openssl/bn.h>
33#include <openssl/dh.h>
34#include <openssl/cast.h>
35#else /* OPENSSL_DHX */
36#include <bn.h>
37#include <dh.h>
38#include <cast.h>
39#endif /* OPENSSL_DHX */
40
41#include <atalk/afp.h>
42#include <atalk/uam.h>
43
44#define KEYSIZE 16
45#define PASSWDLEN 64
46#define CRYPTBUFLEN  (KEYSIZE*2)
47#define CRYPT2BUFLEN (KEYSIZE + PASSWDLEN)
48
49/* hash a number to a 16-bit quantity */
50#define pgphash(a) ((((unsigned long) (a) >> 8) ^ \
51		     (unsigned long) (a)) & 0xffff)
52
53/* the secret key */
54static struct passwd *pgppwd;
55static CAST_KEY castkey;
56static u_int8_t randbuf[16];
57
58/* pgp passwd */
59static int pgp_login(void *obj, struct passwd **uam_pwd,
60		     char *ibuf, size_t ibuflen,
61		     char *rbuf, size_t *rbuflen)
62{
63    size_t len, i;
64    char *name;
65
66    *rbuflen = 0;
67
68    if (uam_afpserver_option(obj, UAM_OPTION_USERNAME, (void *) &name, &i) < 0)
69      return AFPERR_PARAM;
70
71    len = (unsigned char) *ibuf++;
72    if ( len > i ) {
73	return( AFPERR_PARAM );
74    }
75
76    memcpy(name, ibuf, len );
77    ibuf += len;
78    name[ len ] = '\0';
79    if ((unsigned long) ibuf & 1) /* padding */
80      ++ibuf;
81
82    if (( pgppwd = uam_getname(obj, name, i)) == NULL ) {
83      return AFPERR_PARAM;
84    }
85
86    LOG(log_info, logtype_uams, "pgp login: %s", name);
87    if (uam_checkuser(pgppwd) < 0)
88      return AFPERR_NOTAUTH;
89
90    /* get the challenge */
91    len = (unsigned char) *ibuf++;
92    /* challenge */
93
94    /* get the signature. it's always 16 bytes. */
95    if (uam_afpserver_option(obj, UAM_OPTION_SIGNATURE,
96			     (void *) &name, NULL) < 0) {
97      *rbuflen = 0;
98      goto pgp_fail;
99    }
100    memcpy(rbuf + KEYSIZE, name, KEYSIZE);
101
102pgp_fail:
103    return AFPERR_PARAM;
104}
105
106static int pgp_logincont(void *obj, struct passwd **uam_pwd,
107			 char *ibuf, size_t ibuflen,
108			 char *rbuf, size_t *rbuflen)
109{
110	unsigned char iv[] = "RJscorat";
111    BIGNUM *bn1, *bn2, *bn3;
112    u_int16_t sessid;
113    char *p;
114
115    *rbuflen = 0;
116
117    /* check for session id */
118    memcpy(&sessid, ibuf, sizeof(sessid));
119    if (sessid != pgphash(obj))
120      return AFPERR_PARAM;
121    ibuf += sizeof(sessid);
122
123    /* use rbuf as scratch space */
124    CAST_cbc_encrypt(ibuf, rbuf, CRYPT2BUFLEN, &castkey,
125		     iv, CAST_DECRYPT);
126
127    /* check to make sure that the random number is the same. we
128     * get sent back an incremented random number. */
129    if (!(bn1 = BN_bin2bn(rbuf, KEYSIZE, NULL)))
130      return AFPERR_PARAM;
131
132    if (!(bn2 = BN_bin2bn(randbuf, sizeof(randbuf), NULL))) {
133      BN_free(bn1);
134      return AFPERR_PARAM;
135    }
136
137    /* zero out the random number */
138    memset(rbuf, 0, sizeof(randbuf));
139    memset(randbuf, 0, sizeof(randbuf));
140    rbuf += KEYSIZE;
141
142    if (!(bn3 = BN_new())) {
143      BN_free(bn2);
144      BN_free(bn1);
145      return AFPERR_PARAM;
146    }
147
148    BN_sub(bn3, bn1, bn2);
149    BN_free(bn2);
150    BN_free(bn1);
151
152    /* okay. is it one more? */
153    if (!BN_is_one(bn3)) {
154      BN_free(bn3);
155      return AFPERR_PARAM;
156    }
157    BN_free(bn3);
158
159#ifdef AFS
160    if ( kcheckuser(*uam_pwd, rbuf) == 0) {
161      *uam_pwd = pgppwd;
162      return AFP_OK;
163    }
164#endif /* AFS */
165
166    rbuf[PASSWDLEN] = '\0';
167    p = crypt( rbuf, pgppwd->pw_passwd );
168    memset(rbuf, 0, PASSWDLEN);
169    if ( strcmp( p, pgppwd->pw_passwd ) == 0 ) {
170      *uam_pwd = pgppwd;
171      return AFP_OK;
172    }
173
174    return AFPERR_NOTAUTH;
175}
176
177
178static int uam_setup(const char *path)
179{
180  if (uam_register(UAM_SERVER_LOGIN, path, "PGPuam 1.0",
181		   pgp_login, pgp_logincont, NULL) < 0)
182    return -1;
183
184  return 0;
185}
186
187static void uam_cleanup(void)
188{
189  uam_unregister(UAM_SERVER_LOGIN, "PGPuam 1.0");
190}
191
192UAM_MODULE_EXPORT struct uam_export uams_pgp = {
193  UAM_MODULE_SERVER,
194  UAM_MODULE_VERSION,
195  uam_setup, uam_cleanup
196};
197
198#endif /* UAM_PGP */
199