view libtomcrypt/src/pk/asn1/der/ia5/der_length_ia5_string.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 der_length_ia5_string.c
  ASN.1 DER, get length of IA5 STRING, Tom St Denis
*/

#ifdef LTC_DER

static const struct {
   int code, value;
} ia5_table[] = {
{ '\0', 0 },
{ '\a', 7 },
{ '\b', 8 },
{ '\t', 9 },
{ '\n', 10 },
{ '\f', 12 },
{ '\r', 13 },
{ ' ', 32 },
{ '!', 33 },
{ '"', 34 },
{ '#', 35 },
{ '$', 36 },
{ '%', 37 },
{ '&', 38 },
{ '\'', 39 },
{ '(', 40 },
{ ')', 41 },
{ '*', 42 },
{ '+', 43 },
{ ',', 44 },
{ '-', 45 },
{ '.', 46 },
{ '/', 47 },
{ '0', 48 },
{ '1', 49 },
{ '2', 50 },
{ '3', 51 },
{ '4', 52 },
{ '5', 53 },
{ '6', 54 },
{ '7', 55 },
{ '8', 56 },
{ '9', 57 },
{ ':', 58 },
{ ';', 59 },
{ '<', 60 },
{ '=', 61 },
{ '>', 62 },
{ '?', 63 },
{ '@', 64 },
{ 'A', 65 },
{ 'B', 66 },
{ 'C', 67 },
{ 'D', 68 },
{ 'E', 69 },
{ 'F', 70 },
{ 'G', 71 },
{ 'H', 72 },
{ 'I', 73 },
{ 'J', 74 },
{ 'K', 75 },
{ 'L', 76 },
{ 'M', 77 },
{ 'N', 78 },
{ 'O', 79 },
{ 'P', 80 },
{ 'Q', 81 },
{ 'R', 82 },
{ 'S', 83 },
{ 'T', 84 },
{ 'U', 85 },
{ 'V', 86 },
{ 'W', 87 },
{ 'X', 88 },
{ 'Y', 89 },
{ 'Z', 90 },
{ '[', 91 },
{ '\\', 92 },
{ ']', 93 },
{ '^', 94 },
{ '_', 95 },
{ '`', 96 },
{ 'a', 97 },
{ 'b', 98 },
{ 'c', 99 },
{ 'd', 100 },
{ 'e', 101 },
{ 'f', 102 },
{ 'g', 103 },
{ 'h', 104 },
{ 'i', 105 },
{ 'j', 106 },
{ 'k', 107 },
{ 'l', 108 },
{ 'm', 109 },
{ 'n', 110 },
{ 'o', 111 },
{ 'p', 112 },
{ 'q', 113 },
{ 'r', 114 },
{ 's', 115 },
{ 't', 116 },
{ 'u', 117 },
{ 'v', 118 },
{ 'w', 119 },
{ 'x', 120 },
{ 'y', 121 },
{ 'z', 122 },
{ '{', 123 },
{ '|', 124 },
{ '}', 125 },
{ '~', 126 }
};

int der_ia5_char_encode(int c)
{
   int x;
   for (x = 0; x < (int)(sizeof(ia5_table)/sizeof(ia5_table[0])); x++) {
       if (ia5_table[x].code == c) {
          return ia5_table[x].value;
       }
   }
   return -1;
}

int der_ia5_value_decode(int v)
{
   int x;
   for (x = 0; x < (int)(sizeof(ia5_table)/sizeof(ia5_table[0])); x++) {
       if (ia5_table[x].value == v) {
          return ia5_table[x].code;
       }
   }
   return -1;
}

/**
  Gets length of DER encoding of IA5 STRING
  @param octets   The values you want to encode
  @param noctets  The number of octets in the string to encode
  @param outlen   [out] The length of the DER encoding for the given string
  @return CRYPT_OK if successful
*/
int der_length_ia5_string(const unsigned char *octets, unsigned long noctets, unsigned long *outlen)
{
   unsigned long x;

   LTC_ARGCHK(outlen != NULL);
   LTC_ARGCHK(octets != NULL);

   /* scan string for validity */
   for (x = 0; x < noctets; x++) {
       if (der_ia5_char_encode(octets[x]) == -1) {
          return CRYPT_INVALID_ARG;
       }
   }

   if (noctets < 128) {
      /* 16 LL DD DD DD ... */
      *outlen = 2 + noctets;
   } else if (noctets < 256) {
      /* 16 81 LL DD DD DD ... */
      *outlen = 3 + noctets;
   } else if (noctets < 65536UL) {
      /* 16 82 LL LL DD DD DD ... */
      *outlen = 4 + noctets;
   } else if (noctets < 16777216UL) {
      /* 16 83 LL LL LL DD DD DD ... */
      *outlen = 5 + noctets;
   } else {
      return CRYPT_INVALID_ARG;
   }

   return CRYPT_OK;
}

#endif


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