1 /*
2 * Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved.
3 * Copyright 2005 Nokia. All rights reserved.
4 *
5 * Licensed under the Apache License 2.0 (the "License"). You may not use
6 * this file except in compliance with the License. You can obtain a copy
7 * in the file LICENSE in the source distribution or at
8 * https://www.openssl.org/source/license.html
9 */
10
11 /*
12 * This file is to enable backwards compatibility for the SRP features of
13 * s_client, s_server and ciphers. All of those features are deprecated and will
14 * eventually disappear. In the meantime, to continue to support them, we
15 * need to access deprecated SRP APIs.
16 */
17 #define OPENSSL_SUPPRESS_DEPRECATED
18
19 #include <openssl/bn.h>
20 #include <openssl/bio.h>
21 #include <openssl/ssl.h>
22 #include <openssl/srp.h>
23 #include "apps_ui.h"
24 #include "apps.h"
25 #include "s_apps.h"
26
srp_Verify_N_and_g(const BIGNUM * N,const BIGNUM * g)27 static int srp_Verify_N_and_g(const BIGNUM *N, const BIGNUM *g)
28 {
29 BN_CTX *bn_ctx = BN_CTX_new();
30 BIGNUM *p = BN_new();
31 BIGNUM *r = BN_new();
32 int ret =
33 g != NULL && N != NULL && bn_ctx != NULL && BN_is_odd(N) &&
34 BN_check_prime(N, bn_ctx, NULL) == 1 &&
35 p != NULL && BN_rshift1(p, N) &&
36 /* p = (N-1)/2 */
37 BN_check_prime(p, bn_ctx, NULL) == 1 &&
38 r != NULL &&
39 /* verify g^((N-1)/2) == -1 (mod N) */
40 BN_mod_exp(r, g, p, N, bn_ctx) &&
41 BN_add_word(r, 1) && BN_cmp(r, N) == 0;
42
43 BN_free(r);
44 BN_free(p);
45 BN_CTX_free(bn_ctx);
46 return ret;
47 }
48
49 /*-
50 * This callback is used here for two purposes:
51 * - extended debugging
52 * - making some primality tests for unknown groups
53 * The callback is only called for a non default group.
54 *
55 * An application does not need the call back at all if
56 * only the standard groups are used. In real life situations,
57 * client and server already share well known groups,
58 * thus there is no need to verify them.
59 * Furthermore, in case that a server actually proposes a group that
60 * is not one of those defined in RFC 5054, it is more appropriate
61 * to add the group to a static list and then compare since
62 * primality tests are rather cpu consuming.
63 */
64
ssl_srp_verify_param_cb(SSL * s,void * arg)65 static int ssl_srp_verify_param_cb(SSL *s, void *arg)
66 {
67 SRP_ARG *srp_arg = (SRP_ARG *)arg;
68 BIGNUM *N = NULL, *g = NULL;
69
70 if (((N = SSL_get_srp_N(s)) == NULL) || ((g = SSL_get_srp_g(s)) == NULL))
71 return 0;
72 if (srp_arg->debug || srp_arg->msg || srp_arg->amp == 1) {
73 BIO_printf(bio_err, "SRP parameters:\n");
74 BIO_printf(bio_err, "\tN=");
75 BN_print(bio_err, N);
76 BIO_printf(bio_err, "\n\tg=");
77 BN_print(bio_err, g);
78 BIO_printf(bio_err, "\n");
79 }
80
81 if (SRP_check_known_gN_param(g, N))
82 return 1;
83
84 if (srp_arg->amp == 1) {
85 if (srp_arg->debug)
86 BIO_printf(bio_err,
87 "SRP param N and g are not known params, going to check deeper.\n");
88
89 /*
90 * The srp_moregroups is a real debugging feature. Implementors
91 * should rather add the value to the known ones. The minimal size
92 * has already been tested.
93 */
94 if (BN_num_bits(g) <= BN_BITS && srp_Verify_N_and_g(N, g))
95 return 1;
96 }
97 BIO_printf(bio_err, "SRP param N and g rejected.\n");
98 return 0;
99 }
100
101 #define PWD_STRLEN 1024
102
ssl_give_srp_client_pwd_cb(SSL * s,void * arg)103 static char *ssl_give_srp_client_pwd_cb(SSL *s, void *arg)
104 {
105 SRP_ARG *srp_arg = (SRP_ARG *)arg;
106 char *pass = app_malloc(PWD_STRLEN + 1, "SRP password buffer");
107 PW_CB_DATA cb_tmp;
108 int l;
109
110 cb_tmp.password = (char *)srp_arg->srppassin;
111 cb_tmp.prompt_info = "SRP user";
112 if ((l = password_callback(pass, PWD_STRLEN, 0, &cb_tmp)) < 0) {
113 BIO_printf(bio_err, "Can't read Password\n");
114 OPENSSL_free(pass);
115 return NULL;
116 }
117 *(pass + l) = '\0';
118
119 return pass;
120 }
121
set_up_srp_arg(SSL_CTX * ctx,SRP_ARG * srp_arg,int srp_lateuser,int c_msg,int c_debug)122 int set_up_srp_arg(SSL_CTX *ctx, SRP_ARG *srp_arg, int srp_lateuser, int c_msg,
123 int c_debug)
124 {
125 if (!srp_lateuser && !SSL_CTX_set_srp_username(ctx, srp_arg->srplogin)) {
126 BIO_printf(bio_err, "Unable to set SRP username\n");
127 return 0;
128 }
129 srp_arg->msg = c_msg;
130 srp_arg->debug = c_debug;
131 SSL_CTX_set_srp_cb_arg(ctx, &srp_arg);
132 SSL_CTX_set_srp_client_pwd_callback(ctx, ssl_give_srp_client_pwd_cb);
133 SSL_CTX_set_srp_strength(ctx, srp_arg->strength);
134 if (c_msg || c_debug || srp_arg->amp == 0)
135 SSL_CTX_set_srp_verify_param_callback(ctx, ssl_srp_verify_param_cb);
136
137 return 1;
138 }
139
dummy_srp(SSL * ssl,void * arg)140 static char *dummy_srp(SSL *ssl, void *arg)
141 {
142 return "";
143 }
144
set_up_dummy_srp(SSL_CTX * ctx)145 void set_up_dummy_srp(SSL_CTX *ctx)
146 {
147 SSL_CTX_set_srp_client_pwd_callback(ctx, dummy_srp);
148 }
149
150 /*
151 * This callback pretends to require some asynchronous logic in order to
152 * obtain a verifier. When the callback is called for a new connection we
153 * return with a negative value. This will provoke the accept etc to return
154 * with an LOOKUP_X509. The main logic of the reinvokes the suspended call
155 * (which would normally occur after a worker has finished) and we set the
156 * user parameters.
157 */
ssl_srp_server_param_cb(SSL * s,int * ad,void * arg)158 static int ssl_srp_server_param_cb(SSL *s, int *ad, void *arg)
159 {
160 srpsrvparm *p = (srpsrvparm *) arg;
161 int ret = SSL3_AL_FATAL;
162
163 if (p->login == NULL && p->user == NULL) {
164 p->login = SSL_get_srp_username(s);
165 BIO_printf(bio_err, "SRP username = \"%s\"\n", p->login);
166 return -1;
167 }
168
169 if (p->user == NULL) {
170 BIO_printf(bio_err, "User %s doesn't exist\n", p->login);
171 goto err;
172 }
173
174 if (SSL_set_srp_server_param
175 (s, p->user->N, p->user->g, p->user->s, p->user->v,
176 p->user->info) < 0) {
177 *ad = SSL_AD_INTERNAL_ERROR;
178 goto err;
179 }
180 BIO_printf(bio_err,
181 "SRP parameters set: username = \"%s\" info=\"%s\" \n",
182 p->login, p->user->info);
183 ret = SSL_ERROR_NONE;
184
185 err:
186 SRP_user_pwd_free(p->user);
187 p->user = NULL;
188 p->login = NULL;
189 return ret;
190 }
191
set_up_srp_verifier_file(SSL_CTX * ctx,srpsrvparm * srp_callback_parm,char * srpuserseed,char * srp_verifier_file)192 int set_up_srp_verifier_file(SSL_CTX *ctx, srpsrvparm *srp_callback_parm,
193 char *srpuserseed, char *srp_verifier_file)
194 {
195 int ret;
196
197 srp_callback_parm->vb = SRP_VBASE_new(srpuserseed);
198 srp_callback_parm->user = NULL;
199 srp_callback_parm->login = NULL;
200
201 if (srp_callback_parm->vb == NULL) {
202 BIO_printf(bio_err, "Failed to initialize SRP verifier file \n");
203 return 0;
204 }
205 if ((ret =
206 SRP_VBASE_init(srp_callback_parm->vb,
207 srp_verifier_file)) != SRP_NO_ERROR) {
208 BIO_printf(bio_err,
209 "Cannot initialize SRP verifier file \"%s\":ret=%d\n",
210 srp_verifier_file, ret);
211 return 0;
212 }
213 SSL_CTX_set_verify(ctx, SSL_VERIFY_NONE, verify_callback);
214 SSL_CTX_set_srp_cb_arg(ctx, &srp_callback_parm);
215 SSL_CTX_set_srp_username_callback(ctx, ssl_srp_server_param_cb);
216
217 return 1;
218 }
219
lookup_srp_user(srpsrvparm * srp_callback_parm,BIO * bio_s_out)220 void lookup_srp_user(srpsrvparm *srp_callback_parm, BIO *bio_s_out)
221 {
222 SRP_user_pwd_free(srp_callback_parm->user);
223 srp_callback_parm->user = SRP_VBASE_get1_by_user(srp_callback_parm->vb,
224 srp_callback_parm->login);
225
226 if (srp_callback_parm->user != NULL)
227 BIO_printf(bio_s_out, "LOOKUP done %s\n",
228 srp_callback_parm->user->info);
229 else
230 BIO_printf(bio_s_out, "LOOKUP not successful\n");
231 }
232
