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