ssl/tls_srp.c

   1 /*
   2  * Copyright 2004-2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <openssl/crypto.h>
  11 #include <openssl/rand.h>
  12 #include <openssl/err.h>
  13 #include "ssl_locl.h"
  14
  15 #ifndef OPENSSL_NO_SRP
  16 # include <openssl/srp.h>
  17
  18 int SSL_CTX_SRP_CTX_free(struct ssl_ctx_st *ctx)
  19 {
  20     if (ctx == NULL)
  21         return 0;
  22     OPENSSL_free(ctx->srp_ctx.login);
  23     OPENSSL_free(ctx->srp_ctx.info);
  24     BN_free(ctx->srp_ctx.N);
  25     BN_free(ctx->srp_ctx.g);
  26     BN_free(ctx->srp_ctx.s);
  27     BN_free(ctx->srp_ctx.B);
  28     BN_free(ctx->srp_ctx.A);
  29     BN_free(ctx->srp_ctx.a);
  30     BN_free(ctx->srp_ctx.b);
  31     BN_free(ctx->srp_ctx.v);
  32     ctx->srp_ctx.TLS_ext_srp_username_callback = NULL;
  33     ctx->srp_ctx.SRP_cb_arg = NULL;
  34     ctx->srp_ctx.SRP_verify_param_callback = NULL;
  35     ctx->srp_ctx.SRP_give_srp_client_pwd_callback = NULL;
  36     ctx->srp_ctx.N = NULL;
  37     ctx->srp_ctx.g = NULL;
  38     ctx->srp_ctx.s = NULL;
  39     ctx->srp_ctx.B = NULL;
  40     ctx->srp_ctx.A = NULL;
  41     ctx->srp_ctx.a = NULL;
  42     ctx->srp_ctx.b = NULL;
  43     ctx->srp_ctx.v = NULL;
  44     ctx->srp_ctx.login = NULL;
  45     ctx->srp_ctx.info = NULL;
  46     ctx->srp_ctx.strength = SRP_MINIMAL_N;
  47     ctx->srp_ctx.srp_Mask = 0;
  48     return (1);
  49 }
  50
  51 int SSL_SRP_CTX_free(struct ssl_st *s)
  52 {
  53     if (s == NULL)
  54         return 0;
  55     OPENSSL_free(s->srp_ctx.login);
  56     OPENSSL_free(s->srp_ctx.info);
  57     BN_free(s->srp_ctx.N);
  58     BN_free(s->srp_ctx.g);
  59     BN_free(s->srp_ctx.s);
  60     BN_free(s->srp_ctx.B);
  61     BN_free(s->srp_ctx.A);
  62     BN_free(s->srp_ctx.a);
  63     BN_free(s->srp_ctx.b);
  64     BN_free(s->srp_ctx.v);
  65     s->srp_ctx.TLS_ext_srp_username_callback = NULL;
  66     s->srp_ctx.SRP_cb_arg = NULL;
  67     s->srp_ctx.SRP_verify_param_callback = NULL;
  68     s->srp_ctx.SRP_give_srp_client_pwd_callback = NULL;
  69     s->srp_ctx.N = NULL;
  70     s->srp_ctx.g = NULL;
  71     s->srp_ctx.s = NULL;
  72     s->srp_ctx.B = NULL;
  73     s->srp_ctx.A = NULL;
  74     s->srp_ctx.a = NULL;
  75     s->srp_ctx.b = NULL;
  76     s->srp_ctx.v = NULL;
  77     s->srp_ctx.login = NULL;
  78     s->srp_ctx.info = NULL;
  79     s->srp_ctx.strength = SRP_MINIMAL_N;
  80     s->srp_ctx.srp_Mask = 0;
  81     return (1);
  82 }
  83
  84 int SSL_SRP_CTX_init(struct ssl_st *s)
  85 {
  86     SSL_CTX *ctx;
  87
  88     if ((s == NULL) || ((ctx = s->ctx) == NULL))
  89         return 0;
  90     s->srp_ctx.SRP_cb_arg = ctx->srp_ctx.SRP_cb_arg;
  91     /* set client Hello login callback */
  92     s->srp_ctx.TLS_ext_srp_username_callback =
  93         ctx->srp_ctx.TLS_ext_srp_username_callback;
  94     /* set SRP N/g param callback for verification */
  95     s->srp_ctx.SRP_verify_param_callback =
  96         ctx->srp_ctx.SRP_verify_param_callback;
  97     /* set SRP client passwd callback */
  98     s->srp_ctx.SRP_give_srp_client_pwd_callback =
  99         ctx->srp_ctx.SRP_give_srp_client_pwd_callback;
 100
 101     s->srp_ctx.N = NULL;
 102     s->srp_ctx.g = NULL;
 103     s->srp_ctx.s = NULL;
 104     s->srp_ctx.B = NULL;
 105     s->srp_ctx.A = NULL;
 106     s->srp_ctx.a = NULL;
 107     s->srp_ctx.b = NULL;
 108     s->srp_ctx.v = NULL;
 109     s->srp_ctx.login = NULL;
 110     s->srp_ctx.info = NULL;
 111     s->srp_ctx.strength = ctx->srp_ctx.strength;
 112
 113     if (((ctx->srp_ctx.N != NULL) &&
 114          ((s->srp_ctx.N = BN_dup(ctx->srp_ctx.N)) == NULL)) ||
 115         ((ctx->srp_ctx.g != NULL) &&
 116          ((s->srp_ctx.g = BN_dup(ctx->srp_ctx.g)) == NULL)) ||
 117         ((ctx->srp_ctx.s != NULL) &&
 118          ((s->srp_ctx.s = BN_dup(ctx->srp_ctx.s)) == NULL)) ||
 119         ((ctx->srp_ctx.B != NULL) &&
 120          ((s->srp_ctx.B = BN_dup(ctx->srp_ctx.B)) == NULL)) ||
 121         ((ctx->srp_ctx.A != NULL) &&
 122          ((s->srp_ctx.A = BN_dup(ctx->srp_ctx.A)) == NULL)) ||
 123         ((ctx->srp_ctx.a != NULL) &&
 124          ((s->srp_ctx.a = BN_dup(ctx->srp_ctx.a)) == NULL)) ||
 125         ((ctx->srp_ctx.v != NULL) &&
 126          ((s->srp_ctx.v = BN_dup(ctx->srp_ctx.v)) == NULL)) ||
 127         ((ctx->srp_ctx.b != NULL) &&
 128          ((s->srp_ctx.b = BN_dup(ctx->srp_ctx.b)) == NULL))) {
 129         SSLerr(SSL_F_SSL_SRP_CTX_INIT, ERR_R_BN_LIB);
 130         goto err;
 131     }
 132     if ((ctx->srp_ctx.login != NULL) &&
 133         ((s->srp_ctx.login = OPENSSL_strdup(ctx->srp_ctx.login)) == NULL)) {
 134         SSLerr(SSL_F_SSL_SRP_CTX_INIT, ERR_R_INTERNAL_ERROR);
 135         goto err;
 136     }
 137     if ((ctx->srp_ctx.info != NULL) &&
 138         ((s->srp_ctx.info = BUF_strdup(ctx->srp_ctx.info)) == NULL)) {
 139         SSLerr(SSL_F_SSL_SRP_CTX_INIT, ERR_R_INTERNAL_ERROR);
 140         goto err;
 141     }
 142     s->srp_ctx.srp_Mask = ctx->srp_ctx.srp_Mask;
 143
 144     return (1);
 145  err:
 146     OPENSSL_free(s->srp_ctx.login);
 147     OPENSSL_free(s->srp_ctx.info);
 148     BN_free(s->srp_ctx.N);
 149     BN_free(s->srp_ctx.g);
 150     BN_free(s->srp_ctx.s);
 151     BN_free(s->srp_ctx.B);
 152     BN_free(s->srp_ctx.A);
 153     BN_free(s->srp_ctx.a);
 154     BN_free(s->srp_ctx.b);
 155     BN_free(s->srp_ctx.v);
 156     return (0);
 157 }
 158
 159 int SSL_CTX_SRP_CTX_init(struct ssl_ctx_st *ctx)
 160 {
 161     if (ctx == NULL)
 162         return 0;
 163
 164     ctx->srp_ctx.SRP_cb_arg = NULL;
 165     /* set client Hello login callback */
 166     ctx->srp_ctx.TLS_ext_srp_username_callback = NULL;
 167     /* set SRP N/g param callback for verification */
 168     ctx->srp_ctx.SRP_verify_param_callback = NULL;
 169     /* set SRP client passwd callback */
 170     ctx->srp_ctx.SRP_give_srp_client_pwd_callback = NULL;
 171
 172     ctx->srp_ctx.N = NULL;
 173     ctx->srp_ctx.g = NULL;
 174     ctx->srp_ctx.s = NULL;
 175     ctx->srp_ctx.B = NULL;
 176     ctx->srp_ctx.A = NULL;
 177     ctx->srp_ctx.a = NULL;
 178     ctx->srp_ctx.b = NULL;
 179     ctx->srp_ctx.v = NULL;
 180     ctx->srp_ctx.login = NULL;
 181     ctx->srp_ctx.srp_Mask = 0;
 182     ctx->srp_ctx.info = NULL;
 183     ctx->srp_ctx.strength = SRP_MINIMAL_N;
 184
 185     return (1);
 186 }
 187
 188 /* server side */
 189 int SSL_srp_server_param_with_username(SSL *s, int *ad)
 190 {
 191     unsigned char b[SSL_MAX_MASTER_KEY_LENGTH];
 192     int al;
 193
 194     *ad = SSL_AD_UNKNOWN_PSK_IDENTITY;
 195     if ((s->srp_ctx.TLS_ext_srp_username_callback != NULL) &&
 196         ((al =
 197           s->srp_ctx.TLS_ext_srp_username_callback(s, ad,
 198                                                    s->srp_ctx.SRP_cb_arg)) !=
 199          SSL_ERROR_NONE))
 200         return al;
 201
 202     *ad = SSL_AD_INTERNAL_ERROR;
 203     if ((s->srp_ctx.N == NULL) ||
 204         (s->srp_ctx.g == NULL) ||
 205         (s->srp_ctx.s == NULL) || (s->srp_ctx.v == NULL))
 206         return SSL3_AL_FATAL;
 207
 208     if (RAND_bytes(b, sizeof(b)) <= 0)
 209         return SSL3_AL_FATAL;
 210     s->srp_ctx.b = BN_bin2bn(b, sizeof(b), NULL);
 211     OPENSSL_cleanse(b, sizeof(b));
 212
 213     /* Calculate:  B = (kv + g^b) % N  */
 214
 215     return ((s->srp_ctx.B =
 216              SRP_Calc_B(s->srp_ctx.b, s->srp_ctx.N, s->srp_ctx.g,
 217                         s->srp_ctx.v)) !=
 218             NULL) ? SSL_ERROR_NONE : SSL3_AL_FATAL;
 219 }
 220
 221 /*
 222  * If the server just has the raw password, make up a verifier entry on the
 223  * fly
 224  */
 225 int SSL_set_srp_server_param_pw(SSL *s, const char *user, const char *pass,
 226                                 const char *grp)
 227 {
 228     SRP_gN *GN = SRP_get_default_gN(grp);
 229     if (GN == NULL)
 230         return -1;
 231     s->srp_ctx.N = BN_dup(GN->N);
 232     s->srp_ctx.g = BN_dup(GN->g);
 233     BN_clear_free(s->srp_ctx.v);
 234     s->srp_ctx.v = NULL;
 235     BN_clear_free(s->srp_ctx.s);
 236     s->srp_ctx.s = NULL;
 237     if (!SRP_create_verifier_BN
 238         (user, pass, &s->srp_ctx.s, &s->srp_ctx.v, GN->N, GN->g))
 239         return -1;
 240
 241     return 1;
 242 }
 243
 244 int SSL_set_srp_server_param(SSL *s, const BIGNUM *N, const BIGNUM *g,
 245                              BIGNUM *sa, BIGNUM *v, char *info)
 246 {
 247     if (N != NULL) {
 248         if (s->srp_ctx.N != NULL) {
 249             if (!BN_copy(s->srp_ctx.N, N)) {
 250                 BN_free(s->srp_ctx.N);
 251                 s->srp_ctx.N = NULL;
 252             }
 253         } else
 254             s->srp_ctx.N = BN_dup(N);
 255     }
 256     if (g != NULL) {
 257         if (s->srp_ctx.g != NULL) {
 258             if (!BN_copy(s->srp_ctx.g, g)) {
 259                 BN_free(s->srp_ctx.g);
 260                 s->srp_ctx.g = NULL;
 261             }
 262         } else
 263             s->srp_ctx.g = BN_dup(g);
 264     }
 265     if (sa != NULL) {
 266         if (s->srp_ctx.s != NULL) {
 267             if (!BN_copy(s->srp_ctx.s, sa)) {
 268                 BN_free(s->srp_ctx.s);
 269                 s->srp_ctx.s = NULL;
 270             }
 271         } else
 272             s->srp_ctx.s = BN_dup(sa);
 273     }
 274     if (v != NULL) {
 275         if (s->srp_ctx.v != NULL) {
 276             if (!BN_copy(s->srp_ctx.v, v)) {
 277                 BN_free(s->srp_ctx.v);
 278                 s->srp_ctx.v = NULL;
 279             }
 280         } else
 281             s->srp_ctx.v = BN_dup(v);
 282     }
 283     if (info != NULL) {
 284         if (s->srp_ctx.info)
 285             OPENSSL_free(s->srp_ctx.info);
 286         if ((s->srp_ctx.info = BUF_strdup(info)) == NULL)
 287             return -1;
 288     }
 289
 290     if (!(s->srp_ctx.N) ||
 291         !(s->srp_ctx.g) || !(s->srp_ctx.s) || !(s->srp_ctx.v))
 292         return -1;
 293
 294     return 1;
 295 }
 296
 297 int srp_generate_server_master_secret(SSL *s)
 298 {
 299     BIGNUM *K = NULL, *u = NULL;
 300     int ret = -1, tmp_len = 0;
 301     unsigned char *tmp = NULL;
 302
 303     if (!SRP_Verify_A_mod_N(s->srp_ctx.A, s->srp_ctx.N))
 304         goto err;
 305     if ((u = SRP_Calc_u(s->srp_ctx.A, s->srp_ctx.B, s->srp_ctx.N)) == NULL)
 306         goto err;
 307     if ((K = SRP_Calc_server_key(s->srp_ctx.A, s->srp_ctx.v, u, s->srp_ctx.b,
 308                                  s->srp_ctx.N)) == NULL)
 309         goto err;
 310
 311     tmp_len = BN_num_bytes(K);
 312     if ((tmp = OPENSSL_malloc(tmp_len)) == NULL)
 313         goto err;
 314     BN_bn2bin(K, tmp);
 315     ret = ssl_generate_master_secret(s, tmp, tmp_len, 1);
 316  err:
 317     BN_clear_free(K);
 318     BN_clear_free(u);
 319     return ret;
 320 }
 321
 322 /* client side */
 323 int srp_generate_client_master_secret(SSL *s)
 324 {
 325     BIGNUM *x = NULL, *u = NULL, *K = NULL;
 326     int ret = -1, tmp_len = 0;
 327     char *passwd = NULL;
 328     unsigned char *tmp = NULL;
 329
 330     /*
 331      * Checks if b % n == 0
 332      */
 333     if (SRP_Verify_B_mod_N(s->srp_ctx.B, s->srp_ctx.N) == 0)
 334         goto err;
 335     if ((u = SRP_Calc_u(s->srp_ctx.A, s->srp_ctx.B, s->srp_ctx.N)) == NULL)
 336         goto err;
 337     if (s->srp_ctx.SRP_give_srp_client_pwd_callback == NULL)
 338         goto err;
 339     if (!
 340         (passwd =
 341          s->srp_ctx.SRP_give_srp_client_pwd_callback(s, s->srp_ctx.SRP_cb_arg)))
 342         goto err;
 343     if ((x = SRP_Calc_x(s->srp_ctx.s, s->srp_ctx.login, passwd)) == NULL)
 344         goto err;
 345     if ((K = SRP_Calc_client_key(s->srp_ctx.N, s->srp_ctx.B, s->srp_ctx.g, x,
 346                                  s->srp_ctx.a, u)) == NULL)
 347         goto err;
 348
 349     tmp_len = BN_num_bytes(K);
 350     if ((tmp = OPENSSL_malloc(tmp_len)) == NULL)
 351         goto err;
 352     BN_bn2bin(K, tmp);
 353     ret = ssl_generate_master_secret(s, tmp, tmp_len, 1);
 354  err:
 355     BN_clear_free(K);
 356     BN_clear_free(x);
 357     if (passwd != NULL)
 358         OPENSSL_clear_free(passwd, strlen(passwd));
 359     BN_clear_free(u);
 360     return ret;
 361 }
 362
 363 int srp_verify_server_param(SSL *s, int *al)
 364 {
 365     SRP_CTX *srp = &s->srp_ctx;
 366     /*
 367      * Sanity check parameters: we can quickly check B % N == 0 by checking B
 368      * != 0 since B < N
 369      */
 370     if (BN_ucmp(srp->g, srp->N) >= 0 || BN_ucmp(srp->B, srp->N) >= 0
 371         || BN_is_zero(srp->B)) {
 372         *al = SSL3_AD_ILLEGAL_PARAMETER;
 373         return 0;
 374     }
 375
 376     if (BN_num_bits(srp->N) < srp->strength) {
 377         *al = TLS1_AD_INSUFFICIENT_SECURITY;
 378         return 0;
 379     }
 380
 381     if (srp->SRP_verify_param_callback) {
 382         if (srp->SRP_verify_param_callback(s, srp->SRP_cb_arg) <= 0) {
 383             *al = TLS1_AD_INSUFFICIENT_SECURITY;
 384             return 0;
 385         }
 386     } else if (!SRP_check_known_gN_param(srp->g, srp->N)) {
 387         *al = TLS1_AD_INSUFFICIENT_SECURITY;
 388         return 0;
 389     }
 390
 391     return 1;
 392 }
 393
 394 int SRP_Calc_A_param(SSL *s)
 395 {
 396     unsigned char rnd[SSL_MAX_MASTER_KEY_LENGTH];
 397
 398     if (RAND_bytes(rnd, sizeof(rnd)) <= 0)
 399         return 0;
 400     s->srp_ctx.a = BN_bin2bn(rnd, sizeof(rnd), s->srp_ctx.a);
 401     OPENSSL_cleanse(rnd, sizeof(rnd));
 402
 403     if (!(s->srp_ctx.A = SRP_Calc_A(s->srp_ctx.a, s->srp_ctx.N, s->srp_ctx.g)))
 404         return 0;
 405
 406     return 1;
 407 }
 408
 409 BIGNUM *SSL_get_srp_g(SSL *s)
 410 {
 411     if (s->srp_ctx.g != NULL)
 412         return s->srp_ctx.g;
 413     return s->ctx->srp_ctx.g;
 414 }
 415
 416 BIGNUM *SSL_get_srp_N(SSL *s)
 417 {
 418     if (s->srp_ctx.N != NULL)
 419         return s->srp_ctx.N;
 420     return s->ctx->srp_ctx.N;
 421 }
 422
 423 char *SSL_get_srp_username(SSL *s)
 424 {
 425     if (s->srp_ctx.login != NULL)
 426         return s->srp_ctx.login;
 427     return s->ctx->srp_ctx.login;
 428 }
 429
 430 char *SSL_get_srp_userinfo(SSL *s)
 431 {
 432     if (s->srp_ctx.info != NULL)
 433         return s->srp_ctx.info;
 434     return s->ctx->srp_ctx.info;
 435 }
 436
 437 # define tls1_ctx_ctrl ssl3_ctx_ctrl
 438 # define tls1_ctx_callback_ctrl ssl3_ctx_callback_ctrl
 439
 440 int SSL_CTX_set_srp_username(SSL_CTX *ctx, char *name)
 441 {
 442     return tls1_ctx_ctrl(ctx, SSL_CTRL_SET_TLS_EXT_SRP_USERNAME, 0, name);
 443 }
 444
 445 int SSL_CTX_set_srp_password(SSL_CTX *ctx, char *password)
 446 {
 447     return tls1_ctx_ctrl(ctx, SSL_CTRL_SET_TLS_EXT_SRP_PASSWORD, 0, password);
 448 }
 449
 450 int SSL_CTX_set_srp_strength(SSL_CTX *ctx, int strength)
 451 {
 452     return tls1_ctx_ctrl(ctx, SSL_CTRL_SET_TLS_EXT_SRP_STRENGTH, strength,
 453                          NULL);
 454 }
 455
 456 int SSL_CTX_set_srp_verify_param_callback(SSL_CTX *ctx,
 457                                           int (*cb) (SSL *, void *))
 458 {
 459     return tls1_ctx_callback_ctrl(ctx, SSL_CTRL_SET_SRP_VERIFY_PARAM_CB,
 460                                   (void (*)(void))cb);
 461 }
 462
 463 int SSL_CTX_set_srp_cb_arg(SSL_CTX *ctx, void *arg)
 464 {
 465     return tls1_ctx_ctrl(ctx, SSL_CTRL_SET_SRP_ARG, 0, arg);
 466 }
 467
 468 int SSL_CTX_set_srp_username_callback(SSL_CTX *ctx,
 469                                       int (*cb) (SSL *, int *, void *))
 470 {
 471     return tls1_ctx_callback_ctrl(ctx, SSL_CTRL_SET_TLS_EXT_SRP_USERNAME_CB,
 472                                   (void (*)(void))cb);
 473 }
 474
 475 int SSL_CTX_set_srp_client_pwd_callback(SSL_CTX *ctx,
 476                                         char *(*cb) (SSL *, void *))
 477 {
 478     return tls1_ctx_callback_ctrl(ctx, SSL_CTRL_SET_SRP_GIVE_CLIENT_PWD_CB,
 479                                   (void (*)(void))cb);
 480 }
 481
 482 #endif