Commit ddefc056 authored by Daniel Stenberg's avatar Daniel Stenberg
Browse files

openssl: make sure to fail in the unlikely event that PRNG seeding fails

parent 942c952d

lib/vtls/openssl.c

+25 −21
Original line number Diff line number Diff line
@@ -183,13 +183,22 @@ static bool rand_enough(void) 
  return (0 != RAND_status()) ? TRUE : FALSE;

}



static int ossl_seed(struct Curl_easy *data)

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;

  char *buf = data->state.buffer; /* point to the big buffer */

  int nread=0;



  if(rand_enough())

    return 1;

  if(ssl_seeded)

    return CURLE_OK;



  if(rand_enough()) {

    /* OpenSSL 1.1.0+ will return here */

    ssl_seeded = TRUE;

    return CURLE_OK;

  }



#ifndef RANDOM_FILE

  /* if RANDOM_FILE isn't defined, we only perform this if an option tells
@@ -234,9 +243,10 @@ static int ossl_seed(struct Curl_easy *data) 
  do {

    unsigned char randb[64];

    int len = sizeof(randb);

    RAND_bytes(randb, len);

    if(!RAND_bytes(randb, len))

      break;

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

  } while(!RAND_status());

  } while(!rand_enough());



  /* generates a default path for the random seed file */

  buf[0]=0; /* blank it first */
@@ -249,20 +259,7 @@ static int ossl_seed(struct Curl_easy *data) 
  }



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

  return nread;

}



static void 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;



  if(!ssl_seeded || data->set.str[STRING_SSL_RANDOM_FILE] ||

     data->set.str[STRING_SSL_EGDSOCKET]) {

    ossl_seed(data);

    ssl_seeded = TRUE;

  }

  return CURLE_SSL_CONNECT_ERROR; /* confusing error code */

}



#ifndef SSL_FILETYPE_ENGINE
@@ -1710,7 +1707,9 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex) 
  DEBUGASSERT(ssl_connect_1 == connssl->connecting_state);



  /* Make funny stuff to get random input */

  Curl_ossl_seed(data);

  result = Curl_ossl_seed(data);

  if(result)

    return result;



  data->set.ssl.certverifyresult = !X509_V_OK;
@@ -3237,7 +3236,12 @@ int Curl_ossl_random(struct Curl_easy *data, unsigned char *entropy, 
                     size_t length)

{

  if(data) {

    Curl_ossl_seed(data); /* Initiate the seed if not already done */

    if(Curl_ossl_seed(data)) /* Initiate the seed if not already done */

      return 1; /* couldn't seed for some reason */

  }

  else {

    if(!rand_enough())

      return 1;

  }

  RAND_bytes(entropy, curlx_uztosi(length));

  return 0; /* 0 as in no problem */