Commit 1cafede9 authored by Jay Satiro's avatar Jay Satiro Committed by Daniel Stenberg
Browse files

rand: treat fake entropy the same regardless of endianness 

When the random seed is purposely made predictable for testing purposes
by using the CURL_ENTROPY environment variable, process that data in an
endian agnostic way so the the initial random seed is the same
regardless of endianness.

- Change Curl_rand to write to a char array instead of int array.

- Add Curl_rand_hex to write random hex characters to a buffer.

Fixes #1315
Closes #1468

Co-authored-by: Daniel Stenberg
Reported-by: Michael Kaufmann
parent 9e9509e4

lib/formdata.c

+15 −24
Original line number Diff line number Diff line
@@ -48,7 +48,7 @@ static char *Curl_basename(char *path); 
#endif



static size_t readfromfile(struct Form *form, char *buffer, size_t size);

static char *formboundary(struct Curl_easy *data);

static CURLcode formboundary(struct Curl_easy *data, char *buffer, size_t len);



/* What kind of Content-Type to use on un-specified files with unrecognized

   extensions. */
@@ -1159,20 +1159,19 @@ CURLcode Curl_getformdata(struct Curl_easy *data, 
  struct FormData *firstform;

  struct curl_httppost *file;

  CURLcode result = CURLE_OK;



  curl_off_t size = 0; /* support potentially ENORMOUS formposts */

  char *boundary;

  char *fileboundary = NULL;

  char fileboundary[42];

  struct curl_slist *curList;

  char boundary[42];



  *finalform = NULL; /* default form is empty */



  if(!post)

    return result; /* no input => no output! */



  boundary = formboundary(data);

  if(!boundary)

    return CURLE_OUT_OF_MEMORY;

  result = formboundary(data, boundary, sizeof(boundary));

  if(result)

    return result;



  /* Make the first line of the output */

  result = AddFormDataf(&form, NULL,
@@ -1182,7 +1181,6 @@ CURLcode Curl_getformdata(struct Curl_easy *data, 
                        boundary);



  if(result) {

    free(boundary);

    return result;

  }

  /* we DO NOT include that line in the total size of the POST, since it'll be
@@ -1225,10 +1223,8 @@ CURLcode Curl_getformdata(struct Curl_easy *data, 
      /* If used, this is a link to more file names, we must then do

         the magic to include several files with the same field name */



      free(fileboundary);

      fileboundary = formboundary(data);

      if(!fileboundary) {

        result = CURLE_OUT_OF_MEMORY;

      result = formboundary(data, fileboundary, sizeof(fileboundary));

      if(result) {

        break;

      }
@@ -1379,16 +1375,10 @@ CURLcode Curl_getformdata(struct Curl_easy *data, 


  if(result) {

    Curl_formclean(&firstform);

    free(fileboundary);

    free(boundary);

    return result;

  }



  *sizep = size;



  free(fileboundary);

  free(boundary);



  *finalform = firstform;



  return result;
@@ -1562,16 +1552,17 @@ char *Curl_formpostheader(void *formp, size_t *len) 
 * formboundary() creates a suitable boundary string and returns an allocated

 * one.

 */

static char *formboundary(struct Curl_easy *data)

static CURLcode formboundary(struct Curl_easy *data,

                             char *buffer, size_t buflen)

{

  /* 24 dashes and 16 hexadecimal digits makes 64 bit (18446744073709551615)

     combinations */

  unsigned int rnd[2];

  CURLcode result = Curl_rand(data, &rnd[0], 2);

  if(result)

    return NULL;

  DEBUGASSERT(buflen >= 41);



  memset(buffer, '-', 24);

  Curl_rand_hex(data, (unsigned char *)&buffer[24], 17);



  return aprintf("------------------------%08x%08x", rnd[0], rnd[1]);

  return CURLE_OK;

}



#else  /* CURL_DISABLE_HTTP */

lib/rand.c

+54 −7
Original line number Diff line number Diff line
@@ -47,10 +47,12 @@ static CURLcode randit(struct Curl_easy *data, unsigned int *rnd) 
  char *force_entropy = getenv("CURL_ENTROPY");

  if(force_entropy) {

    if(!seeded) {

      unsigned int seed = 0;

      size_t elen = strlen(force_entropy);

      size_t clen = sizeof(randseed);

      size_t clen = sizeof(seed);

      size_t min = elen < clen ? elen : clen;

      memcpy((char *)&randseed, force_entropy, min);

      memcpy((char *)&seed, force_entropy, min);

      randseed = ntohl(seed);

      seeded = TRUE;

    }

    else
@@ -115,18 +117,63 @@ static CURLcode randit(struct Curl_easy *data, unsigned int *rnd) 
 *

 */



CURLcode Curl_rand(struct Curl_easy *data, unsigned int *rndptr,

                   unsigned int num)

CURLcode Curl_rand(struct Curl_easy *data, unsigned char *rnd, size_t num)

{

  CURLcode result = CURLE_BAD_FUNCTION_ARGUMENT;

  unsigned int i;



  assert(num > 0);



  for(i = 0; i < num; i++) {

    result = randit(data, rndptr++);

  while(num) {

    unsigned int r;

    size_t left = num < sizeof(unsigned int) ? num : sizeof(unsigned int);



    result = randit(data, &r);

    if(result)

      return result;



    while(left) {

      *rnd++ = (unsigned char)(r & 0xFF);

      r >>= 8;

      --num;

      --left;

    }

  }



  return result;

}



/*

 * Curl_rand_hex() fills the 'rnd' buffer with a given 'num' size with random

 * hexadecimal digits PLUS a zero terminating byte. It must be an odd number

 * size.

 */



CURLcode Curl_rand_hex(struct Curl_easy *data, unsigned char *rnd,

                       size_t num)

{

  CURLcode result = CURLE_BAD_FUNCTION_ARGUMENT;

  const char *hex = "0123456789abcdef";

  unsigned char buffer[128];

  unsigned char *bufp = buffer;

  DEBUGASSERT(num > 1);



  if((num/2 >= sizeof(buffer)) || !(num&1))

    /* make sure it fits in the local buffer and that it is an odd number! */

    return CURLE_BAD_FUNCTION_ARGUMENT;



  num--; /* save one for zero termination */



  result = Curl_rand(data, buffer, num/2);

  if(result)

    return result;



  while(num) {

    *rnd++ = hex[(*bufp & 0xF0)>>4];

    *rnd++ = hex[*bufp & 0x0F];

    bufp++;

    num -= 2;

  }

  *rnd = 0;



  return result;

}

lib/rand.h

+8 −4
Original line number Diff line number Diff line
@@ -7,7 +7,7 @@ 
 *                            | (__| |_| |  _ <| |___

 *                             \___|\___/|_| \_\_____|

 *

 * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel@haxx.se>, et al.

 * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.

 *

 * This software is licensed as described in the file COPYING, which

 * you should have received as part of this distribution. The terms
@@ -23,7 +23,7 @@ 
 ***************************************************************************/



/*

 * Curl_rand() stores 'num' number of random unsigned integers in the buffer

 * Curl_rand() stores 'num' number of random unsigned characters in the buffer

 * 'rnd' points to.

 *

 * If libcurl is built without TLS support or with a TLS backend that lacks a
@@ -37,7 +37,11 @@ 
 * easy handle!

 *

 */

CURLcode Curl_rand(struct Curl_easy *data, unsigned int *rnd,

                   unsigned int num);

CURLcode Curl_rand(struct Curl_easy *data, unsigned char *rnd, size_t num);



/* Same as above but outputs only random lowercase hex characters.

   Does NOT terminate.*/

CURLcode Curl_rand_hex(struct Curl_easy *data, unsigned char *rnd,

                       size_t num);



#endif /* HEADER_CURL_RAND_H */

lib/vauth/digest.c

+4 −11
Original line number Diff line number Diff line
@@ -360,7 +360,6 @@ CURLcode Curl_auth_create_digest_md5_message(struct Curl_easy *data, 
  char qop_options[64];

  int qop_values;

  char cnonce[33];

  unsigned int entropy[4];

  char nonceCount[] = "00000001";

  char method[]     = "AUTHENTICATE";

  char qop[]        = DIGEST_QOP_VALUE_STRING_AUTH;
@@ -387,15 +386,11 @@ CURLcode Curl_auth_create_digest_md5_message(struct Curl_easy *data, 
  if(!(qop_values & DIGEST_QOP_VALUE_AUTH))

    return CURLE_BAD_CONTENT_ENCODING;



  /* Generate 16 bytes of random data */

  result = Curl_rand(data, &entropy[0], 4);

  /* Generate 32 random hex chars, 32 bytes + 1 zero termination */

  result = Curl_rand_hex(data, (unsigned char *)cnonce, sizeof(cnonce));

  if(result)

    return result;



  /* Convert the random data into a 32 byte hex string */

  snprintf(cnonce, sizeof(cnonce), "%08x%08x%08x%08x",

           entropy[0], entropy[1], entropy[2], entropy[3]);



  /* So far so good, now calculate A1 and H(A1) according to RFC 2831 */

  ctxt = Curl_MD5_init(Curl_DIGEST_MD5);

  if(!ctxt)
@@ -684,12 +679,10 @@ CURLcode Curl_auth_create_digest_http_message(struct Curl_easy *data, 
    digest->nc = 1;



  if(!digest->cnonce) {

    unsigned int rnd[4];

    result = Curl_rand(data, &rnd[0], 4);

    result = Curl_rand_hex(data, (unsigned char *)cnoncebuf,

                           sizeof(cnoncebuf));

    if(result)

      return result;

    snprintf(cnoncebuf, sizeof(cnoncebuf), "%08x%08x%08x%08x",

             rnd[0], rnd[1], rnd[2], rnd[3]);



    result = Curl_base64_encode(data, cnoncebuf, strlen(cnoncebuf),

                                &cnonce, &cnonce_sz);

lib/vauth/ntlm.c

+6 −8
Original line number Diff line number Diff line
@@ -555,10 +555,10 @@ CURLcode Curl_auth_create_ntlm_type3_message(struct Curl_easy *data, 
#if defined(USE_NTRESPONSES) && defined(USE_NTLM_V2)

  if(ntlm->target_info_len) {

    unsigned char ntbuffer[0x18];

    unsigned int entropy[2];

    unsigned char entropy[8];

    unsigned char ntlmv2hash[0x18];



    result = Curl_rand(data, &entropy[0], 2);

    result = Curl_rand(data, entropy, 8);

    if(result)

      return result;
@@ -572,15 +572,13 @@ CURLcode Curl_auth_create_ntlm_type3_message(struct Curl_easy *data, 
      return result;



    /* LMv2 response */

    result = Curl_ntlm_core_mk_lmv2_resp(ntlmv2hash,

                                         (unsigned char *)&entropy[0],

    result = Curl_ntlm_core_mk_lmv2_resp(ntlmv2hash, entropy,

                                         &ntlm->nonce[0], lmresp);

    if(result)

      return result;



    /* NTLMv2 response */

    result = Curl_ntlm_core_mk_ntlmv2_resp(ntlmv2hash,

                                           (unsigned char *)&entropy[0],

    result = Curl_ntlm_core_mk_ntlmv2_resp(ntlmv2hash, entropy,

                                           ntlm, &ntlmv2resp, &ntresplen);

    if(result)

      return result;
@@ -596,10 +594,10 @@ CURLcode Curl_auth_create_ntlm_type3_message(struct Curl_easy *data, 
    unsigned char ntbuffer[0x18];

    unsigned char tmp[0x18];

    unsigned char md5sum[MD5_DIGEST_LENGTH];

    unsigned int entropy[2];

    unsigned char entropy[8];



    /* Need to create 8 bytes random data */

    result = Curl_rand(data, &entropy[0], 2);

    result = Curl_rand(data, entropy, 8);

    if(result)

      return result;