annotate libtomcrypt/src/pk/asn1/der/bit/der_encode_raw_bit_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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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 #include "tomcrypt.h"
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10
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11 /**
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12 @file der_encode_bit_string.c
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13 ASN.1 DER, encode a BIT STRING, Tom St Denis
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14 */
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15
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16
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17 #ifdef LTC_DER
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18
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19 #define getbit(n, k) (((n) & ( 1 << (k) )) >> (k))
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20
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21 /**
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22 Store a BIT STRING
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23 @param in The array of bits to store (8 per char)
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24 @param inlen The number of bits to store
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25 @param out [out] The destination for the DER encoded BIT STRING
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26 @param outlen [in/out] The max size and resulting size of the DER BIT STRING
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27 @return CRYPT_OK if successful
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28 */
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29 int der_encode_raw_bit_string(const unsigned char *in, unsigned long inlen,
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30 unsigned char *out, unsigned long *outlen)
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31 {
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32 unsigned long len, x, y;
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33 unsigned char buf;
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34 int err;
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35
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36 LTC_ARGCHK(in != NULL);
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37 LTC_ARGCHK(out != NULL);
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38 LTC_ARGCHK(outlen != NULL);
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39
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40 /* avoid overflows */
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41 if ((err = der_length_bit_string(inlen, &len)) != CRYPT_OK) {
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42 return err;
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43 }
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44
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45 if (len > *outlen) {
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46 *outlen = len;
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47 return CRYPT_BUFFER_OVERFLOW;
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48 }
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49
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50 /* store header (include bit padding count in length) */
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51 x = 0;
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52 y = (inlen >> 3) + ((inlen&7) ? 1 : 0) + 1;
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53
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54 out[x++] = 0x03;
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55 if (y < 128) {
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56 out[x++] = (unsigned char)y;
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57 } else if (y < 256) {
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58 out[x++] = 0x81;
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59 out[x++] = (unsigned char)y;
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60 } else if (y < 65536) {
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61 out[x++] = 0x82;
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62 out[x++] = (unsigned char)((y>>8)&255);
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63 out[x++] = (unsigned char)(y&255);
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64 }
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65
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66 /* store number of zero padding bits */
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67 out[x++] = (unsigned char)((8 - inlen) & 7);
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68
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69 /* store the bits in big endian format */
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70 for (y = buf = 0; y < inlen; y++) {
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71 buf |= (getbit(in[y/8],7-y%8)?1:0) << (7 - (y & 7));
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72 if ((y & 7) == 7) {
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73 out[x++] = buf;
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74 buf = 0;
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75 }
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76 }
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77 /* store last byte */
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78 if (inlen & 7) {
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79 out[x++] = buf;
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80 }
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81
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82 *outlen = x;
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83 return CRYPT_OK;
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84 }
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85
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86 #endif
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87
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88 /* ref: $Format:%D$ */
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89 /* git commit: $Format:%H$ */
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90 /* commit time: $Format:%ai$ */