Mercurial > dropbear

view libtomcrypt/src/pk/asn1/der/sequence/der_decode_sequence_ex.c @ 1930:299f4f19ba19

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
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
line wrap: on
line source

/* 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_decode_sequence_ex.c
  ASN.1 DER, decode a SEQUENCE, Tom St Denis
*/

#ifdef LTC_DER

/**
   Decode a SEQUENCE
   @param in       The DER encoded input
   @param inlen    The size of the input
   @param list     The list of items to decode
   @param outlen   The number of items in the list
   @param ordered  Search an unordeded or ordered list
   @return CRYPT_OK on success
*/
int der_decode_sequence_ex(const unsigned char *in, unsigned long  inlen,
                           ltc_asn1_list *list,     unsigned long  outlen, int ordered)
{
   int           err, i;
   ltc_asn1_type type;
   unsigned long size, x, y, z, blksize;
   void          *data;

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

   /* get blk size */
   if (inlen < 2) {
      return CRYPT_INVALID_PACKET;
   }

   /* sequence type? We allow 0x30 SEQUENCE and 0x31 SET since fundamentally they're the same structure */
   x = 0;
   if (in[x] != 0x30 && in[x] != 0x31) {
      return CRYPT_INVALID_PACKET;
   }
   ++x;

   /* check if the msb is set, which signals that the
    * 7 lsb bits represent the number of bytes of the length
    */
   if (in[x] < 128) {
      blksize = in[x++];
   } else {
      if (in[x] < 0x81 || in[x] > 0x83) {
         return CRYPT_INVALID_PACKET;
      }
      y = in[x++] & 0x7F;

      /* would reading the len bytes overrun? */
      if (x + y > inlen) {
         return CRYPT_INVALID_PACKET;
      }

      /* read len */
      blksize = 0;
      while (y--) {
          blksize = (blksize << 8) | (unsigned long)in[x++];
      }
   }

   /* would this blksize overflow? */
   if (x + blksize > inlen) {
      return CRYPT_INVALID_PACKET;
   }

   /* mark all as unused */
   for (i = 0; i < (int)outlen; i++) {
       list[i].used = 0;
   }

   /* ok read data */
   inlen = blksize;
   for (i = 0; i < (int)outlen; i++) {
       z    = 0;
       type = list[i].type;
       size = list[i].size;
       data = list[i].data;
       if (!ordered && list[i].used == 1) { continue; }

       if (type == LTC_ASN1_EOL) {
          break;
       }

       switch (type) {
           case LTC_ASN1_BOOLEAN:
               z = inlen;
               if ((err = der_decode_boolean(in + x, z, ((int *)data))) != CRYPT_OK) {
                   if (!ordered) { continue; }
                   goto LBL_ERR;
               }
               if ((err = der_length_boolean(&z)) != CRYPT_OK) {
                   goto LBL_ERR;
               }
               break;

           case LTC_ASN1_INTEGER:
               z = inlen;
               if ((err = der_decode_integer(in + x, z, data)) != CRYPT_OK) {
                  if (!ordered) {  continue; }
                  goto LBL_ERR;
               }
               if ((err = der_length_integer(data, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               break;

           case LTC_ASN1_SHORT_INTEGER:
               z = inlen;
               if ((err = der_decode_short_integer(in + x, z, data)) != CRYPT_OK) {
                  if (!ordered) { continue; }
                  goto LBL_ERR;
               }
               if ((err = der_length_short_integer(((unsigned long*)data)[0], &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }

               break;

           case LTC_ASN1_BIT_STRING:
               z = inlen;
               if ((err = der_decode_bit_string(in + x, z, data, &size)) != CRYPT_OK) {
                  if (!ordered) { continue; }
                  goto LBL_ERR;
               }
               list[i].size = size;
               if ((err = der_length_bit_string(size, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               break;

           case LTC_ASN1_RAW_BIT_STRING:
               z = inlen;
               if ((err = der_decode_raw_bit_string(in + x, z, data, &size)) != CRYPT_OK) {
                  if (!ordered) { continue; }
                  goto LBL_ERR;
               }
               list[i].size = size;
               if ((err = der_length_bit_string(size, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               break;

           case LTC_ASN1_OCTET_STRING:
               z = inlen;
               if ((err = der_decode_octet_string(in + x, z, data, &size)) != CRYPT_OK) {
                  if (!ordered) { continue; }
                  goto LBL_ERR;
               }
               list[i].size = size;
               if ((err = der_length_octet_string(size, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               break;

           case LTC_ASN1_NULL:
               if (inlen < 2 || in[x] != 0x05 || in[x+1] != 0x00) {
                  if (!ordered) { continue; }
                  err = CRYPT_INVALID_PACKET;
                  goto LBL_ERR;
               }
               z = 2;
               break;

           case LTC_ASN1_OBJECT_IDENTIFIER:
               z = inlen;
               if ((err = der_decode_object_identifier(in + x, z, data, &size)) != CRYPT_OK) {
                  if (!ordered) { continue; }
                  goto LBL_ERR;
               }
               list[i].size = size;
               if ((err = der_length_object_identifier(data, size, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               break;

           case LTC_ASN1_TELETEX_STRING:
               z = inlen;
               if ((err = der_decode_teletex_string(in + x, z, data, &size)) != CRYPT_OK) {
                  if (!ordered) { continue; }
                  goto LBL_ERR;
               }
               list[i].size = size;
               if ((err = der_length_teletex_string(data, size, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               break;

           case LTC_ASN1_IA5_STRING:
               z = inlen;
               if ((err = der_decode_ia5_string(in + x, z, data, &size)) != CRYPT_OK) {
                  if (!ordered) { continue; }
                  goto LBL_ERR;
               }
               list[i].size = size;
               if ((err = der_length_ia5_string(data, size, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               break;


           case LTC_ASN1_PRINTABLE_STRING:
               z = inlen;
               if ((err = der_decode_printable_string(in + x, z, data, &size)) != CRYPT_OK) {
                  if (!ordered) { continue; }
                  goto LBL_ERR;
               }
               list[i].size = size;
               if ((err = der_length_printable_string(data, size, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               break;

           case LTC_ASN1_UTF8_STRING:
               z = inlen;
               if ((err = der_decode_utf8_string(in + x, z, data, &size)) != CRYPT_OK) {
                  if (!ordered) { continue; }
                  goto LBL_ERR;
               }
               list[i].size = size;
               if ((err = der_length_utf8_string(data, size, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               break;

           case LTC_ASN1_UTCTIME:
               z = inlen;
               if ((err = der_decode_utctime(in + x, &z, data)) != CRYPT_OK) {
                  if (!ordered) { continue; }
                  goto LBL_ERR;
               }
               break;

           case LTC_ASN1_GENERALIZEDTIME:
               z = inlen;
               if ((err = der_decode_generalizedtime(in + x, &z, data)) != CRYPT_OK) {
                  if (!ordered) { continue; }
                  goto LBL_ERR;
               }
               break;

           case LTC_ASN1_SET:
               z = inlen;
               if ((err = der_decode_set(in + x, z, data, size)) != CRYPT_OK) {
                  if (!ordered) { continue; }
                  goto LBL_ERR;
               }
               if ((err = der_length_sequence(data, size, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               break;

           case LTC_ASN1_SETOF:
           case LTC_ASN1_SEQUENCE:
               /* detect if we have the right type */
               if ((type == LTC_ASN1_SETOF && (in[x] & 0x3F) != 0x31) || (type == LTC_ASN1_SEQUENCE && (in[x] & 0x3F) != 0x30)) {
                  err = CRYPT_INVALID_PACKET;
                  goto LBL_ERR;
               }

               z = inlen;
               if ((err = der_decode_sequence(in + x, z, data, size)) != CRYPT_OK) {
                  if (!ordered) { continue; }
                  goto LBL_ERR;
               }
               if ((err = der_length_sequence(data, size, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               break;


           case LTC_ASN1_CHOICE:
               z = inlen;
               if ((err = der_decode_choice(in + x, &z, data, size)) != CRYPT_OK) {
                  if (!ordered) { continue; }
                  goto LBL_ERR;
               }
               break;

           case LTC_ASN1_CONSTRUCTED:
           case LTC_ASN1_CONTEXT_SPECIFIC:
           case LTC_ASN1_EOL:
               err = CRYPT_INVALID_ARG;
               goto LBL_ERR;
       }
       x           += z;
       inlen       -= z;
       list[i].used = 1;
       if (!ordered) {
          /* restart the decoder */
          i = -1;
       }
   }

   for (i = 0; i < (int)outlen; i++) {
      if (list[i].used == 0) {
          err = CRYPT_INVALID_PACKET;
          goto LBL_ERR;
      }
   }

   if (inlen == 0) {
      err = CRYPT_OK;
   } else {
      err = CRYPT_INPUT_TOO_LONG;
   }

LBL_ERR:
   return err;
}

#endif

/* ref:         $Format:%D$ */
/* git commit:  $Format:%H$ */
/* commit time: $Format:%ai$ */