view libtomcrypt/src/mac/blake2/blake2smac_file.c @ 1930:299f4f19ba19

Add /usr/sbin and /sbin to default root PATH When dropbear is used in a very restricted environment (such as in a initrd), the default user shell is often also very restricted and doesn't take care of setting the PATH so the user ends up with the PATH set by dropbear. Unfortunately, dropbear always sets "/usr/bin:/bin" as default PATH even for the root user which should have /usr/sbin and /sbin too. For a concrete instance of this problem, see the "Remote Unlocking" section in this tutorial: https://paxswill.com/blog/2013/11/04/encrypted-raspberry-pi/ It speaks of a bug in the initramfs script because it's written "blkid" instead of "/sbin/blkid"... this is just because the scripts from the initramfs do not expect to have a PATH without the sbin directories and because dropbear is not setting the PATH appropriately for the root user. I'm thus suggesting to use the attached patch to fix this misbehaviour (I did not test it, but it's easy enough). It might seem anecdotic but multiple Kali users have been bitten by this. From https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=903403
author Raphael Hertzog <hertzog@debian.org>
date Mon, 09 Jul 2018 16:27:53 +0200
parents e9dba7abd939
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_BLAKE2SMAC

/**
  BLAKE2S MAC a file
  @param fname    The name of the file you wish to BLAKE2S MAC
  @param key      The secret key
  @param keylen   The length of the secret key
  @param mac      [out] The BLAKE2S MAC authentication tag
  @param maclen   [in/out]  The max size and resulting size of the authentication tag
  @return CRYPT_OK if successful, CRYPT_NOP if file support has been disabled
*/
int blake2smac_file(const char *fname, const unsigned char *key, unsigned long keylen, unsigned char *mac, unsigned long *maclen)
{
#ifdef LTC_NO_FILE
   LTC_UNUSED_PARAM(fname);
   LTC_UNUSED_PARAM(key);
   LTC_UNUSED_PARAM(keylen);
   LTC_UNUSED_PARAM(mac);
   LTC_UNUSED_PARAM(maclen);
   return CRYPT_NOP;
#else
   blake2smac_state st;
   FILE *in;
   unsigned char *buf;
   size_t x;
   int err;

   LTC_ARGCHK(fname  != NULL);
   LTC_ARGCHK(key    != NULL);
   LTC_ARGCHK(mac    != NULL);
   LTC_ARGCHK(maclen != NULL);

   if ((buf = XMALLOC(LTC_FILE_READ_BUFSIZE)) == NULL) {
      return CRYPT_MEM;
   }

   if ((err = blake2smac_init(&st, *maclen, key, keylen)) != CRYPT_OK) {
      goto LBL_ERR;
   }

   in = fopen(fname, "rb");
   if (in == NULL) {
      err = CRYPT_FILE_NOTFOUND;
      goto LBL_ERR;
   }

   do {
      x = fread(buf, 1, LTC_FILE_READ_BUFSIZE, in);
      if ((err = blake2smac_process(&st, buf, (unsigned long)x)) != CRYPT_OK) {
         fclose(in);
         goto LBL_CLEANBUF;
      }
   } while (x == LTC_FILE_READ_BUFSIZE);

   if (fclose(in) != 0) {
      err = CRYPT_ERROR;
      goto LBL_CLEANBUF;
   }

   err = blake2smac_done(&st, mac, maclen);

LBL_CLEANBUF:
   zeromem(buf, LTC_FILE_READ_BUFSIZE);
LBL_ERR:
#ifdef LTC_CLEAN_STACK
   zeromem(&st, sizeof(blake2smac_state));
#endif
   XFREE(buf);
   return err;
#endif
}

#endif

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