view libtomcrypt/src/hashes/helper/hash_memory.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"

#ifdef LTC_HASH_HELPERS
/**
  @file hash_memory.c
  Hash memory helper, Tom St Denis
*/

/**
  Hash a block of memory and store the digest.
  @param hash   The index of the hash you wish to use
  @param in     The data you wish to hash
  @param inlen  The length of the data to hash (octets)
  @param out    [out] Where to store the digest
  @param outlen [in/out] Max size and resulting size of the digest
  @return CRYPT_OK if successful
*/
int hash_memory(int hash, const unsigned char *in, unsigned long inlen, unsigned char *out, unsigned long *outlen)
{
    hash_state *md;
    int err;

    LTC_ARGCHK(in     != NULL);
    LTC_ARGCHK(out    != NULL);
    LTC_ARGCHK(outlen != NULL);

    if ((err = hash_is_valid(hash)) != CRYPT_OK) {
        return err;
    }

    if (*outlen < hash_descriptor[hash].hashsize) {
       *outlen = hash_descriptor[hash].hashsize;
       return CRYPT_BUFFER_OVERFLOW;
    }

    md = XMALLOC(sizeof(hash_state));
    if (md == NULL) {
       return CRYPT_MEM;
    }

    if ((err = hash_descriptor[hash].init(md)) != CRYPT_OK) {
       goto LBL_ERR;
    }
    if ((err = hash_descriptor[hash].process(md, in, inlen)) != CRYPT_OK) {
       goto LBL_ERR;
    }
    err = hash_descriptor[hash].done(md, out);
    *outlen = hash_descriptor[hash].hashsize;
LBL_ERR:
#ifdef LTC_CLEAN_STACK
    zeromem(md, sizeof(hash_state));
#endif
    XFREE(md);

    return err;
}
#endif /* #ifdef LTC_HASH_HELPERS */

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