view libtomcrypt/src/misc/crypt/crypt_find_cipher_any.c @ 1715:3974f087d9c0

Disallow leading lines before the ident for server (#102) Per RFC4253 4.2 clients must be able to process other lines of data before the version string, server behavior is not defined neither with MUST/SHOULD nor with MAY. If server process up to 50 lines too - it may cause too long hanging session with invalid/evil client that consume host resources and potentially may lead to DDoS on poor embedded boxes. Let's require first line from client to be version string and fail early if it's not - matches both RFC and real OpenSSH behavior.
author Vladislav Grishenko <themiron@users.noreply.github.com>
date Mon, 15 Jun 2020 18:22:18 +0500
parents 6dba84798cd5
children
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 *
 * LibTomCrypt is a library that provides various cryptographic
 * algorithms in a highly modular and flexible manner.
 *
 * The library is free for all purposes without any express
 * guarantee it works.
 */
#include "tomcrypt.h"

/**
  @file crypt_find_cipher_any.c
  Find a cipher in the descriptor tables, Tom St Denis
*/

/**
   Find a cipher flexibly.  First by name then if not present by block and key size
   @param name        The name of the cipher desired
   @param blocklen    The minimum length of the block cipher desired (octets)
   @param keylen      The minimum length of the key size desired (octets)
   @return >= 0 if found, -1 if not present
*/
int find_cipher_any(const char *name, int blocklen, int keylen)
{
   int x;

   if(name != NULL) {
      x = find_cipher(name);
      if (x != -1) return x;
   }

   LTC_MUTEX_LOCK(&ltc_cipher_mutex);
   for (x = 0; x < TAB_SIZE; x++) {
       if (cipher_descriptor[x].name == NULL) {
          continue;
       }
       if (blocklen <= (int)cipher_descriptor[x].block_length && keylen <= (int)cipher_descriptor[x].max_key_length) {
          LTC_MUTEX_UNLOCK(&ltc_cipher_mutex);
          return x;
       }
   }
   LTC_MUTEX_UNLOCK(&ltc_cipher_mutex);
   return -1;
}

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