Commit 19287705 authored by Dmitry Kostjuchenko's avatar Dmitry Kostjuchenko Committed by Daniel Stenberg
Browse files

openssl: improve fallback seed of PRNG with a time based hash 

Fixes #1620
parent f8f040e6

lib/vtls/openssl.c

+26 −17
Original line number Diff line number Diff line
@@ -236,7 +236,6 @@ static CURLcode Curl_ossl_seed(struct Curl_easy *data) 
  /* we have the "SSL is seeded" boolean static to prevent multiple

     time-consuming seedings in vain */

  static bool ssl_seeded = FALSE;

  int nread=0;

  char fname[256];



  if(ssl_seeded)
@@ -256,12 +255,12 @@ static CURLcode Curl_ossl_seed(struct Curl_easy *data) 
#endif

  {

    /* let the option override the define */

    nread += RAND_load_file((data->set.str[STRING_SSL_RANDOM_FILE]?

    RAND_load_file((data->set.str[STRING_SSL_RANDOM_FILE]?

                    data->set.str[STRING_SSL_RANDOM_FILE]:

                    RANDOM_FILE),

                   RAND_LOAD_LENGTH);

    if(rand_enough())

      return nread;

      return CURLE_OK;

  }



#if defined(HAVE_RAND_EGD)
@@ -279,21 +278,30 @@ static CURLcode Curl_ossl_seed(struct Curl_easy *data) 
    int ret = RAND_egd(data->set.str[STRING_SSL_EGDSOCKET]?

                       data->set.str[STRING_SSL_EGDSOCKET]:EGD_SOCKET);

    if(-1 != ret) {

      nread += ret;

      if(rand_enough())

        return nread;

        return CURLE_OK;

    }

  }

#endif



  /* If we get here, it means we need to seed the PRNG using a "silly"

     approach! */

  /* fallback to a custom seeding of the PRNG using a hash based on a current

     time */

  do {

    unsigned char randb[64];

    int len = sizeof(randb);

    if(!RAND_bytes(randb, len))

      break;

    RAND_add(randb, len, (len >> 1));

    size_t len = sizeof(randb);

    size_t i, i_max;

    for(i = 0, i_max = len / sizeof(struct timeval); i < i_max; ++i) {

      struct timeval tv = curlx_tvnow();

      Curl_wait_ms(1);

      tv.tv_sec *= i + 1;

      tv.tv_usec *= i + 2;

      tv.tv_sec ^= ((curlx_tvnow().tv_sec + curlx_tvnow().tv_usec) *

                    (i + 3)) << 8;

      tv.tv_usec ^= ((curlx_tvnow().tv_sec + curlx_tvnow().tv_usec) *

                     (i + 4)) << 16;

      memcpy(&randb[i * sizeof(struct timeval)], &tv, sizeof(struct timeval));

    }

    RAND_add(randb, (int)len, (double)len/2);

  } while(!rand_enough());



  /* generates a default path for the random seed file */
@@ -301,13 +309,14 @@ static CURLcode Curl_ossl_seed(struct Curl_easy *data) 
  RAND_file_name(fname, sizeof(fname));

  if(fname[0]) {

    /* we got a file name to try */

    nread += RAND_load_file(fname, RAND_LOAD_LENGTH);

    RAND_load_file(fname, RAND_LOAD_LENGTH);

    if(rand_enough())

      return nread;

      return CURLE_OK;

  }



  infof(data, "libcurl is now using a weak random seed!\n");

  return CURLE_SSL_CONNECT_ERROR; /* confusing error code */

  return (rand_enough() ? CURLE_OK :

    CURLE_SSL_CONNECT_ERROR /* confusing error code */);

}



#ifndef SSL_FILETYPE_ENGINE