view libtomcrypt/src/math/radix_to_bin.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 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 radix_to_bin.c
   Convert data from a specific radix to binary.
   Steffen Jaeckel
*/

/**
   Convert data from a specific radix to binary

      The default MPI descriptors #ltm_desc, #tfm_desc and #gmp_desc
      have the following restrictions on parameters:

        \p in    - NUL-terminated char buffer

        \p radix - 2..64

   @param in    The input
   @param radix The radix of the input
   @param out   The output buffer
   @param len   [in/out] The length of the output buffer

   @return CRYPT_OK on success.
*/
int radix_to_bin(const void *in, int radix, void *out, unsigned long *len)
{
   unsigned long l;
   void* mpi;
   int err;

   LTC_ARGCHK(in  != NULL);
   LTC_ARGCHK(len != NULL);

   if ((err = mp_init(&mpi)) != CRYPT_OK) return err;
   if ((err = mp_read_radix(mpi, in, radix)) != CRYPT_OK) goto LBL_ERR;

   if ((l = mp_unsigned_bin_size(mpi)) > *len) {
      *len = l;
      err = CRYPT_BUFFER_OVERFLOW;
      goto LBL_ERR;
   }
   *len = l;

   if ((err = mp_to_unsigned_bin(mpi, out)) != CRYPT_OK) goto LBL_ERR;

LBL_ERR:
   mp_clear(mpi);
   return err;
}

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