annotate libtomcrypt/src/pk/dh/dh_export.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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1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
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2 *
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3 * LibTomCrypt is a library that provides various cryptographic
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4 * algorithms in a highly modular and flexible manner.
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5 *
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6 * The library is free for all purposes without any express
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7 * guarantee it works.
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8 */
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9
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10 #include "tomcrypt.h"
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11
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12 #ifdef LTC_MDH
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13
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14 /**
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15 Export a DH key to a binary packet
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16 @param out [out] The destination for the key
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17 @param outlen [in/out] The max size and resulting size of the DH key
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18 @param type Which type of key (PK_PRIVATE or PK_PUBLIC)
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19 @param key The key you wish to export
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20 @return CRYPT_OK if successful
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21 */
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22 int dh_export(unsigned char *out, unsigned long *outlen, int type, dh_key *key)
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23 {
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24 unsigned char flags[1];
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25 int err;
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26 unsigned long version = 0;
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27
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28 LTC_ARGCHK(out != NULL);
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29 LTC_ARGCHK(outlen != NULL);
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30 LTC_ARGCHK(key != NULL);
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31
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32 if (type == PK_PRIVATE) {
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33 /* export x - private key */
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34 flags[0] = 1;
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35 err = der_encode_sequence_multi(out, outlen,
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36 LTC_ASN1_SHORT_INTEGER, 1UL, &version,
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37 LTC_ASN1_BIT_STRING, 1UL, flags,
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38 LTC_ASN1_INTEGER, 1UL, key->prime,
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39 LTC_ASN1_INTEGER, 1UL, key->base,
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40 LTC_ASN1_INTEGER, 1UL, key->x,
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41 LTC_ASN1_EOL, 0UL, NULL);
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42 }
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43 else {
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44 /* export y - public key */
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45 flags[0] = 0;
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46 err = der_encode_sequence_multi(out, outlen,
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47 LTC_ASN1_SHORT_INTEGER, 1UL, &version,
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48 LTC_ASN1_BIT_STRING, 1UL, flags,
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49 LTC_ASN1_INTEGER, 1UL, key->prime,
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50 LTC_ASN1_INTEGER, 1UL, key->base,
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51 LTC_ASN1_INTEGER, 1UL, key->y,
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52 LTC_ASN1_EOL, 0UL, NULL);
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53 }
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54
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55 return err;
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56 }
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57
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58 #endif /* LTC_MDH */
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59
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60 /* ref: $Format:%D$ */
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61 /* git commit: $Format:%H$ */
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62 /* commit time: $Format:%ai$ */