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/*
* Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved.
* Copyright 2005 Nokia. All rights reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
/*
* This file is to enable backwards compatibility for the SRP features of
* s_client, s_server and ciphers. All of those features are deprecated and will
* eventually disappear. In the meantime, to continue to support them, we
* need to access deprecated SRP APIs.
*/
#define OPENSSL_SUPPRESS_DEPRECATED
#include <openssl/bn.h>
#include <openssl/bio.h>
#include <openssl/ssl.h>
#include <openssl/srp.h>
#include "apps_ui.h"
#include "apps.h"
#include "s_apps.h"
static int srp_Verify_N_and_g(const BIGNUM *N, const BIGNUM *g)
{
BN_CTX *bn_ctx = BN_CTX_new();
BIGNUM *p = BN_new();
BIGNUM *r = BN_new();
int ret =
g != NULL && N != NULL && bn_ctx != NULL && BN_is_odd(N) &&
BN_check_prime(N, bn_ctx, NULL) == 1 &&
p != NULL && BN_rshift1(p, N) &&
/* p = (N-1)/2 */
BN_check_prime(p, bn_ctx, NULL) == 1 &&
r != NULL &&
/* verify g^((N-1)/2) == -1 (mod N) */
BN_mod_exp(r, g, p, N, bn_ctx) &&
BN_add_word(r, 1) && BN_cmp(r, N) == 0;
BN_free(r);
BN_free(p);
BN_CTX_free(bn_ctx);
return ret;
}
/*-
* This callback is used here for two purposes:
* - extended debugging
* - making some primality tests for unknown groups
* The callback is only called for a non default group.
*
* An application does not need the call back at all if
* only the standard groups are used. In real life situations,
* client and server already share well known groups,
* thus there is no need to verify them.
* Furthermore, in case that a server actually proposes a group that
* is not one of those defined in RFC 5054, it is more appropriate
* to add the group to a static list and then compare since
* primality tests are rather cpu consuming.
*/
static int ssl_srp_verify_param_cb(SSL *s, void *arg)
{
SRP_ARG *srp_arg = (SRP_ARG *)arg;
BIGNUM *N = NULL, *g = NULL;
if (((N = SSL_get_srp_N(s)) == NULL) || ((g = SSL_get_srp_g(s)) == NULL))
return 0;
if (srp_arg->debug || srp_arg->msg || srp_arg->amp == 1) {
BIO_printf(bio_err, "SRP parameters:\n");
BIO_printf(bio_err, "\tN=");
BN_print(bio_err, N);
BIO_printf(bio_err, "\n\tg=");
BN_print(bio_err, g);
BIO_printf(bio_err, "\n");
}
if (SRP_check_known_gN_param(g, N))
return 1;
if (srp_arg->amp == 1) {
if (srp_arg->debug)
BIO_printf(bio_err,
"SRP param N and g are not known params, going to check deeper.\n");
/*
* The srp_moregroups is a real debugging feature. Implementors
* should rather add the value to the known ones. The minimal size
* has already been tested.
*/
if (BN_num_bits(g) <= BN_BITS && srp_Verify_N_and_g(N, g))
return 1;
}
BIO_printf(bio_err, "SRP param N and g rejected.\n");
return 0;
}
#define PWD_STRLEN 1024
static char *ssl_give_srp_client_pwd_cb(SSL *s, void *arg)
{
SRP_ARG *srp_arg = (SRP_ARG *)arg;
char *pass = app_malloc(PWD_STRLEN + 1, "SRP password buffer");
PW_CB_DATA cb_tmp;
int l;
cb_tmp.password = (char *)srp_arg->srppassin;
cb_tmp.prompt_info = "SRP user";
if ((l = password_callback(pass, PWD_STRLEN, 0, &cb_tmp)) < 0) {
BIO_printf(bio_err, "Can't read Password\n");
OPENSSL_free(pass);
return NULL;
}
*(pass + l) = '\0';
return pass;
}
int set_up_srp_arg(SSL_CTX *ctx, SRP_ARG *srp_arg, int srp_lateuser, int c_msg,
int c_debug)
{
if (!srp_lateuser && !SSL_CTX_set_srp_username(ctx, srp_arg->srplogin)) {
BIO_printf(bio_err, "Unable to set SRP username\n");
return 0;
}
srp_arg->msg = c_msg;
srp_arg->debug = c_debug;
SSL_CTX_set_srp_cb_arg(ctx, &srp_arg);
SSL_CTX_set_srp_client_pwd_callback(ctx, ssl_give_srp_client_pwd_cb);
SSL_CTX_set_srp_strength(ctx, srp_arg->strength);
if (c_msg || c_debug || srp_arg->amp == 0)
SSL_CTX_set_srp_verify_param_callback(ctx, ssl_srp_verify_param_cb);
return 1;
}
static char *dummy_srp(SSL *ssl, void *arg)
{
return "";
}
void set_up_dummy_srp(SSL_CTX *ctx)
{
SSL_CTX_set_srp_client_pwd_callback(ctx, dummy_srp);
}
/*
* This callback pretends to require some asynchronous logic in order to
* obtain a verifier. When the callback is called for a new connection we
* return with a negative value. This will provoke the accept etc to return
* with an LOOKUP_X509. The main logic of the reinvokes the suspended call
* (which would normally occur after a worker has finished) and we set the
* user parameters.
*/
static int ssl_srp_server_param_cb(SSL *s, int *ad, void *arg)
{
srpsrvparm *p = (srpsrvparm *) arg;
int ret = SSL3_AL_FATAL;
if (p->login == NULL && p->user == NULL) {
p->login = SSL_get_srp_username(s);
BIO_printf(bio_err, "SRP username = \"%s\"\n", p->login);
return -1;
}
if (p->user == NULL) {
BIO_printf(bio_err, "User %s doesn't exist\n", p->login);
goto err;
}
if (SSL_set_srp_server_param
(s, p->user->N, p->user->g, p->user->s, p->user->v,
p->user->info) < 0) {
*ad = SSL_AD_INTERNAL_ERROR;
goto err;
}
BIO_printf(bio_err,
"SRP parameters set: username = \"%s\" info=\"%s\" \n",
p->login, p->user->info);
ret = SSL_ERROR_NONE;
err:
SRP_user_pwd_free(p->user);
p->user = NULL;
p->login = NULL;
return ret;
}
int set_up_srp_verifier_file(SSL_CTX *ctx, srpsrvparm *srp_callback_parm,
char *srpuserseed, char *srp_verifier_file)
{
int ret;
srp_callback_parm->vb = SRP_VBASE_new(srpuserseed);
srp_callback_parm->user = NULL;
srp_callback_parm->login = NULL;
if (srp_callback_parm->vb == NULL) {
BIO_printf(bio_err, "Failed to initialize SRP verifier file \n");
return 0;
}
if ((ret =
SRP_VBASE_init(srp_callback_parm->vb,
srp_verifier_file)) != SRP_NO_ERROR) {
BIO_printf(bio_err,
"Cannot initialize SRP verifier file \"%s\":ret=%d\n",
srp_verifier_file, ret);
return 0;
}
SSL_CTX_set_verify(ctx, SSL_VERIFY_NONE, verify_callback);
SSL_CTX_set_srp_cb_arg(ctx, &srp_callback_parm);
SSL_CTX_set_srp_username_callback(ctx, ssl_srp_server_param_cb);
return 1;
}
void lookup_srp_user(srpsrvparm *srp_callback_parm, BIO *bio_s_out)
{
SRP_user_pwd_free(srp_callback_parm->user);
srp_callback_parm->user = SRP_VBASE_get1_by_user(srp_callback_parm->vb,
srp_callback_parm->login);
if (srp_callback_parm->user != NULL)
BIO_printf(bio_s_out, "LOOKUP done %s\n",
srp_callback_parm->user->info);
else
BIO_printf(bio_s_out, "LOOKUP not successful\n");
}
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