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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.
 */

/*******************************************************************************
*
* FILE:           safer.c
*
* LTC_DESCRIPTION:    block-cipher algorithm LTC_SAFER (Secure And Fast Encryption
*                 Routine) in its four versions: LTC_SAFER K-64, LTC_SAFER K-128,
*                 LTC_SAFER SK-64 and LTC_SAFER SK-128.
*
* AUTHOR:         Richard De Moliner ([email protected])
*                 Signal and Information Processing Laboratory
*                 Swiss Federal Institute of Technology
*                 CH-8092 Zuerich, Switzerland
*
* DATE:           September 9, 1995
*
* CHANGE HISTORY:
*
*******************************************************************************/

#include "tomcrypt.h"

#ifdef LTC_SAFER

#define __LTC_SAFER_TAB_C__
#include "safer_tab.c"

const struct ltc_cipher_descriptor safer_k64_desc = {
   "safer-k64",
   8, 8, 8, 8, LTC_SAFER_K64_DEFAULT_NOF_ROUNDS,
   &safer_k64_setup,
   &safer_ecb_encrypt,
   &safer_ecb_decrypt,
   &safer_k64_test,
   &safer_done,
   &safer_64_keysize,
   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
   },

   safer_sk64_desc = {
   "safer-sk64",
   9, 8, 8, 8, LTC_SAFER_SK64_DEFAULT_NOF_ROUNDS,
   &safer_sk64_setup,
   &safer_ecb_encrypt,
   &safer_ecb_decrypt,
   &safer_sk64_test,
   &safer_done,
   &safer_64_keysize,
   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
   },

   safer_k128_desc = {
   "safer-k128",
   10, 16, 16, 8, LTC_SAFER_K128_DEFAULT_NOF_ROUNDS,
   &safer_k128_setup,
   &safer_ecb_encrypt,
   &safer_ecb_decrypt,
   &safer_sk128_test,
   &safer_done,
   &safer_128_keysize,
   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
   },

   safer_sk128_desc = {
   "safer-sk128",
   11, 16, 16, 8, LTC_SAFER_SK128_DEFAULT_NOF_ROUNDS,
   &safer_sk128_setup,
   &safer_ecb_encrypt,
   &safer_ecb_decrypt,
   &safer_sk128_test,
   &safer_done,
   &safer_128_keysize,
   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
   };

/******************* Constants ************************************************/
/* #define TAB_LEN      256  */

/******************* Assertions ***********************************************/

/******************* Macros ***************************************************/
#define ROL8(x, n)   ((unsigned char)((unsigned int)(x) << (n)\
                                     |(unsigned int)((x) & 0xFF) >> (8 - (n))))
#define EXP(x)       safer_ebox[(x) & 0xFF]
#define LOG(x)       safer_lbox[(x) & 0xFF]
#define PHT(x, y)    { y += x; x += y; }
#define IPHT(x, y)   { x -= y; y -= x; }

/******************* Types ****************************************************/

#ifdef LTC_CLEAN_STACK
static void _Safer_Expand_Userkey(const unsigned char *userkey_1,
                                 const unsigned char *userkey_2,
                                 unsigned int nof_rounds,
                                 int strengthened,
                                 safer_key_t key)
#else
static void Safer_Expand_Userkey(const unsigned char *userkey_1,
                                 const unsigned char *userkey_2,
                                 unsigned int nof_rounds,
                                 int strengthened,
                                 safer_key_t key)
#endif
{   unsigned int i, j, k;
    unsigned char ka[LTC_SAFER_BLOCK_LEN + 1];
    unsigned char kb[LTC_SAFER_BLOCK_LEN + 1];

    if (LTC_SAFER_MAX_NOF_ROUNDS < nof_rounds)
        nof_rounds = LTC_SAFER_MAX_NOF_ROUNDS;
    *key++ = (unsigned char)nof_rounds;
    ka[LTC_SAFER_BLOCK_LEN] = (unsigned char)0;
    kb[LTC_SAFER_BLOCK_LEN] = (unsigned char)0;
    k = 0;
    for (j = 0; j < LTC_SAFER_BLOCK_LEN; j++) {
        ka[j] = ROL8(userkey_1[j], 5);
        ka[LTC_SAFER_BLOCK_LEN] ^= ka[j];
        kb[j] = *key++ = userkey_2[j];
        kb[LTC_SAFER_BLOCK_LEN] ^= kb[j];
    }
    for (i = 1; i <= nof_rounds; i++) {
        for (j = 0; j < LTC_SAFER_BLOCK_LEN + 1; j++) {
            ka[j] = ROL8(ka[j], 6);
            kb[j] = ROL8(kb[j], 6);
        }
        if (strengthened) {
           k = 2 * i - 1;
           while (k >= (LTC_SAFER_BLOCK_LEN + 1)) { k -= LTC_SAFER_BLOCK_LEN + 1; }
        }
        for (j = 0; j < LTC_SAFER_BLOCK_LEN; j++) {
            if (strengthened) {
                *key++ = (ka[k]
                                + safer_ebox[(int)safer_ebox[(int)((18 * i + j + 1)&0xFF)]]) & 0xFF;
                if (++k == (LTC_SAFER_BLOCK_LEN + 1)) { k = 0; }
            } else {
                *key++ = (ka[j] + safer_ebox[(int)safer_ebox[(int)((18 * i + j + 1)&0xFF)]]) & 0xFF;
            }
        }
        if (strengthened) {
           k = 2 * i;
           while (k >= (LTC_SAFER_BLOCK_LEN + 1)) { k -= LTC_SAFER_BLOCK_LEN + 1; }
        }
        for (j = 0; j < LTC_SAFER_BLOCK_LEN; j++) {
            if (strengthened) {
                *key++ = (kb[k]
                                + safer_ebox[(int)safer_ebox[(int)((18 * i + j + 10)&0xFF)]]) & 0xFF;
                if (++k == (LTC_SAFER_BLOCK_LEN + 1)) { k = 0; }
            } else {
                *key++ = (kb[j] + safer_ebox[(int)safer_ebox[(int)((18 * i + j + 10)&0xFF)]]) & 0xFF;
            }
        }
    }

#ifdef LTC_CLEAN_STACK
    zeromem(ka, sizeof(ka));
    zeromem(kb, sizeof(kb));
#endif
}

#ifdef LTC_CLEAN_STACK
static void Safer_Expand_Userkey(const unsigned char *userkey_1,
                                 const unsigned char *userkey_2,
                                 unsigned int nof_rounds,
                                 int strengthened,
                                 safer_key_t key)
{
   _Safer_Expand_Userkey(userkey_1, userkey_2, nof_rounds, strengthened, key);
   burn_stack(sizeof(unsigned char) * (2 * (LTC_SAFER_BLOCK_LEN + 1)) + sizeof(unsigned int)*2);
}
#endif

int safer_k64_setup(const unsigned char *key, int keylen, int numrounds, symmetric_key *skey)
{
   LTC_ARGCHK(key != NULL);
   LTC_ARGCHK(skey != NULL);

   if (numrounds != 0 && (numrounds < 6 || numrounds > LTC_SAFER_MAX_NOF_ROUNDS)) {
      return CRYPT_INVALID_ROUNDS;
   }

   if (keylen != 8) {
      return CRYPT_INVALID_KEYSIZE;
   }

   Safer_Expand_Userkey(key, key, (unsigned int)(numrounds != 0 ?numrounds:LTC_SAFER_K64_DEFAULT_NOF_ROUNDS), 0, skey->safer.key);
   return CRYPT_OK;
}

int safer_sk64_setup(const unsigned char *key, int keylen, int numrounds, symmetric_key *skey)
{
   LTC_ARGCHK(key != NULL);
   LTC_ARGCHK(skey != NULL);

   if (numrounds != 0 && (numrounds < 6 || numrounds > LTC_SAFER_MAX_NOF_ROUNDS)) {
      return CRYPT_INVALID_ROUNDS;
   }

   if (keylen != 8) {
      return CRYPT_INVALID_KEYSIZE;
   }

   Safer_Expand_Userkey(key, key, (unsigned int)(numrounds != 0 ?numrounds:LTC_SAFER_SK64_DEFAULT_NOF_ROUNDS), 1, skey->safer.key);
   return CRYPT_OK;
}

int safer_k128_setup(const unsigned char *key, int keylen, int numrounds, symmetric_key *skey)
{
   LTC_ARGCHK(key != NULL);
   LTC_ARGCHK(skey != NULL);

   if (numrounds != 0 && (numrounds < 6 || numrounds > LTC_SAFER_MAX_NOF_ROUNDS)) {
      return CRYPT_INVALID_ROUNDS;
   }

   if (keylen != 16) {
      return CRYPT_INVALID_KEYSIZE;
   }

   Safer_Expand_Userkey(key, key+8, (unsigned int)(numrounds != 0 ?numrounds:LTC_SAFER_K128_DEFAULT_NOF_ROUNDS), 0, skey->safer.key);
   return CRYPT_OK;
}

int safer_sk128_setup(const unsigned char *key, int keylen, int numrounds, symmetric_key *skey)
{
   LTC_ARGCHK(key != NULL);
   LTC_ARGCHK(skey != NULL);

   if (numrounds != 0 && (numrounds < 6 || numrounds > LTC_SAFER_MAX_NOF_ROUNDS)) {
      return CRYPT_INVALID_ROUNDS;
   }

   if (keylen != 16) {
      return CRYPT_INVALID_KEYSIZE;
   }

   Safer_Expand_Userkey(key, key+8, (unsigned int)(numrounds != 0?numrounds:LTC_SAFER_SK128_DEFAULT_NOF_ROUNDS), 1, skey->safer.key);
   return CRYPT_OK;
}

#ifdef LTC_CLEAN_STACK
static int _safer_ecb_encrypt(const unsigned char *block_in,
                             unsigned char *block_out,
                             symmetric_key *skey)
#else
int safer_ecb_encrypt(const unsigned char *block_in,
                             unsigned char *block_out,
                             symmetric_key *skey)
#endif
{   unsigned char a, b, c, d, e, f, g, h, t;
    unsigned int round;
    unsigned char *key;

    LTC_ARGCHK(block_in != NULL);
    LTC_ARGCHK(block_out != NULL);
    LTC_ARGCHK(skey != NULL);

    key = skey->safer.key;
    a = block_in[0]; b = block_in[1]; c = block_in[2]; d = block_in[3];
    e = block_in[4]; f = block_in[5]; g = block_in[6]; h = block_in[7];
    if (LTC_SAFER_MAX_NOF_ROUNDS < (round = *key)) round = LTC_SAFER_MAX_NOF_ROUNDS;
    while(round-- > 0)
    {
        a ^= *++key; b += *++key; c += *++key; d ^= *++key;
        e ^= *++key; f += *++key; g += *++key; h ^= *++key;
        a = EXP(a) + *++key; b = LOG(b) ^ *++key;
        c = LOG(c) ^ *++key; d = EXP(d) + *++key;
        e = EXP(e) + *++key; f = LOG(f) ^ *++key;
        g = LOG(g) ^ *++key; h = EXP(h) + *++key;
        PHT(a, b); PHT(c, d); PHT(e, f); PHT(g, h);
        PHT(a, c); PHT(e, g); PHT(b, d); PHT(f, h);
        PHT(a, e); PHT(b, f); PHT(c, g); PHT(d, h);
        t = b; b = e; e = c; c = t; t = d; d = f; f = g; g = t;
    }
    a ^= *++key; b += *++key; c += *++key; d ^= *++key;
    e ^= *++key; f += *++key; g += *++key; h ^= *++key;
    block_out[0] = a & 0xFF; block_out[1] = b & 0xFF;
    block_out[2] = c & 0xFF; block_out[3] = d & 0xFF;
    block_out[4] = e & 0xFF; block_out[5] = f & 0xFF;
    block_out[6] = g & 0xFF; block_out[7] = h & 0xFF;
    return CRYPT_OK;
}

#ifdef LTC_CLEAN_STACK
int safer_ecb_encrypt(const unsigned char *block_in,
                             unsigned char *block_out,
                             symmetric_key *skey)
{
    int err = _safer_ecb_encrypt(block_in, block_out, skey);
    burn_stack(sizeof(unsigned char) * 9 + sizeof(unsigned int) + sizeof(unsigned char *));
    return err;
}
#endif

#ifdef LTC_CLEAN_STACK
static int _safer_ecb_decrypt(const unsigned char *block_in,
                             unsigned char *block_out,
                             symmetric_key *skey)
#else
int safer_ecb_decrypt(const unsigned char *block_in,
                             unsigned char *block_out,
                             symmetric_key *skey)
#endif
{   unsigned char a, b, c, d, e, f, g, h, t;
    unsigned int round;
    unsigned char *key;

    LTC_ARGCHK(block_in != NULL);
    LTC_ARGCHK(block_out != NULL);
    LTC_ARGCHK(skey != NULL);

    key = skey->safer.key;
    a = block_in[0]; b = block_in[1]; c = block_in[2]; d = block_in[3];
    e = block_in[4]; f = block_in[5]; g = block_in[6]; h = block_in[7];
    if (LTC_SAFER_MAX_NOF_ROUNDS < (round = *key)) round = LTC_SAFER_MAX_NOF_ROUNDS;
    key += LTC_SAFER_BLOCK_LEN * (1 + 2 * round);
    h ^= *key; g -= *--key; f -= *--key; e ^= *--key;
    d ^= *--key; c -= *--key; b -= *--key; a ^= *--key;
    while (round--)
    {
        t = e; e = b; b = c; c = t; t = f; f = d; d = g; g = t;
        IPHT(a, e); IPHT(b, f); IPHT(c, g); IPHT(d, h);
        IPHT(a, c); IPHT(e, g); IPHT(b, d); IPHT(f, h);
        IPHT(a, b); IPHT(c, d); IPHT(e, f); IPHT(g, h);
        h -= *--key; g ^= *--key; f ^= *--key; e -= *--key;
        d -= *--key; c ^= *--key; b ^= *--key; a -= *--key;
        h = LOG(h) ^ *--key; g = EXP(g) - *--key;
        f = EXP(f) - *--key; e = LOG(e) ^ *--key;
        d = LOG(d) ^ *--key; c = EXP(c) - *--key;
        b = EXP(b) - *--key; a = LOG(a) ^ *--key;
    }
    block_out[0] = a & 0xFF; block_out[1] = b & 0xFF;
    block_out[2] = c & 0xFF; block_out[3] = d & 0xFF;
    block_out[4] = e & 0xFF; block_out[5] = f & 0xFF;
    block_out[6] = g & 0xFF; block_out[7] = h & 0xFF;
    return CRYPT_OK;
}

#ifdef LTC_CLEAN_STACK
int safer_ecb_decrypt(const unsigned char *block_in,
                             unsigned char *block_out,
                             symmetric_key *skey)
{
    int err = _safer_ecb_decrypt(block_in, block_out, skey);
    burn_stack(sizeof(unsigned char) * 9 + sizeof(unsigned int) + sizeof(unsigned char *));
    return err;
}
#endif

int safer_64_keysize(int *keysize)
{
   LTC_ARGCHK(keysize != NULL);
   if (*keysize < 8) {
      return CRYPT_INVALID_KEYSIZE;
   } else {
      *keysize = 8;
      return CRYPT_OK;
   }
}

int safer_128_keysize(int *keysize)
{
   LTC_ARGCHK(keysize != NULL);
   if (*keysize < 16) {
      return CRYPT_INVALID_KEYSIZE;
   } else {
      *keysize = 16;
      return CRYPT_OK;
   }
}

int safer_k64_test(void)
{
 #ifndef LTC_TEST
    return CRYPT_NOP;
 #else
   static const unsigned char k64_pt[]  = { 1, 2, 3, 4, 5, 6, 7, 8 },
                              k64_key[] = { 8, 7, 6, 5, 4, 3, 2, 1 },
                              k64_ct[]  = { 200, 242, 156, 221, 135, 120, 62, 217 };

   symmetric_key skey;
   unsigned char buf[2][8];
   int err;

   /* test K64 */
   if ((err = safer_k64_setup(k64_key, 8, 6, &skey)) != CRYPT_OK) {
      return err;
   }
   safer_ecb_encrypt(k64_pt, buf[0], &skey);
   safer_ecb_decrypt(buf[0], buf[1], &skey);

   if (compare_testvector(buf[0], 8, k64_ct, 8, "Safer K64 Encrypt", 0) != 0 ||
         compare_testvector(buf[1], 8, k64_pt, 8, "Safer K64 Decrypt", 0) != 0) {
      return CRYPT_FAIL_TESTVECTOR;
   }

   return CRYPT_OK;
 #endif
}


int safer_sk64_test(void)
{
 #ifndef LTC_TEST
    return CRYPT_NOP;
 #else
   static const unsigned char sk64_pt[]  = { 1, 2, 3, 4, 5, 6, 7, 8 },
                              sk64_key[] = { 1, 2, 3, 4, 5, 6, 7, 8 },
                              sk64_ct[]  = { 95, 206, 155, 162, 5, 132, 56, 199 };

   symmetric_key skey;
   unsigned char buf[2][8];
   int err, y;

   /* test SK64 */
   if ((err = safer_sk64_setup(sk64_key, 8, 6, &skey)) != CRYPT_OK) {
      return err;
   }

   safer_ecb_encrypt(sk64_pt, buf[0], &skey);
   safer_ecb_decrypt(buf[0], buf[1], &skey);

   if (compare_testvector(buf[0], 8, sk64_ct, 8, "Safer SK64 Encrypt", 0) != 0 ||
         compare_testvector(buf[1], 8, sk64_pt, 8, "Safer SK64 Decrypt", 0) != 0) {
      return CRYPT_FAIL_TESTVECTOR;
   }

   /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */
   for (y = 0; y < 8; y++) buf[0][y] = 0;
   for (y = 0; y < 1000; y++) safer_ecb_encrypt(buf[0], buf[0], &skey);
   for (y = 0; y < 1000; y++) safer_ecb_decrypt(buf[0], buf[0], &skey);
   for (y = 0; y < 8; y++) if (buf[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;

   return CRYPT_OK;
  #endif
}

/** Terminate the context
   @param skey    The scheduled key
*/
void safer_done(symmetric_key *skey)
{
  LTC_UNUSED_PARAM(skey);
}

int safer_sk128_test(void)
{
 #ifndef LTC_TEST
    return CRYPT_NOP;
 #else
   static const unsigned char sk128_pt[]  = { 1, 2, 3, 4, 5, 6, 7, 8 },
                              sk128_key[] = { 1, 2, 3, 4, 5, 6, 7, 8,
                                              0, 0, 0, 0, 0, 0, 0, 0 },
                              sk128_ct[]  = { 255, 120, 17, 228, 179, 167, 46, 113 };

   symmetric_key skey;
   unsigned char buf[2][8];
   int err, y;

   /* test SK128 */
   if ((err = safer_sk128_setup(sk128_key, 16, 0, &skey)) != CRYPT_OK) {
      return err;
   }
   safer_ecb_encrypt(sk128_pt, buf[0], &skey);
   safer_ecb_decrypt(buf[0], buf[1], &skey);

   if (compare_testvector(buf[0], 8, sk128_ct, 8, "Safer SK128 Encrypt", 0) != 0 ||
         compare_testvector(buf[1], 8, sk128_pt, 8, "Safer SK128 Decrypt", 0) != 0) {
      return CRYPT_FAIL_TESTVECTOR;
   }

   /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */
   for (y = 0; y < 8; y++) buf[0][y] = 0;
   for (y = 0; y < 1000; y++) safer_ecb_encrypt(buf[0], buf[0], &skey);
   for (y = 0; y < 1000; y++) safer_ecb_decrypt(buf[0], buf[0], &skey);
   for (y = 0; y < 8; y++) if (buf[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;

   return CRYPT_OK;
 #endif
}

#endif




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