Mercurial > dropbear
annotate libtomcrypt/src/pk/asn1/der/bit/der_decode_raw_bit_string.c @ 1804:f0cd000f3bca
Prevent multiple shells being spawned
Existing shells would be leaked.
The old check only caught multiple commands, not shells.
author | Matt Johnston <matt@ucc.asn.au> |
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date | Sat, 06 Mar 2021 23:06:43 +0800 |
parents | 6dba84798cd5 |
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rev | line source |
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1471
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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_decode_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 SETBIT(v, n) (v=((unsigned char)(v) | (1U << (unsigned char)(n)))) |
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20 #define CLRBIT(v, n) (v=((unsigned char)(v) & ~(1U << (unsigned char)(n)))) |
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21 |
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22 /** |
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23 Store a BIT STRING |
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24 @param in The DER encoded BIT STRING |
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25 @param inlen The size of the DER BIT STRING |
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26 @param out [out] The array of bits stored (8 per char) |
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27 @param outlen [in/out] The number of bits stored |
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28 @return CRYPT_OK if successful |
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29 */ |
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30 int der_decode_raw_bit_string(const unsigned char *in, unsigned long inlen, |
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31 unsigned char *out, unsigned long *outlen) |
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32 { |
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33 unsigned long dlen, blen, x, y; |
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34 |
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35 LTC_ARGCHK(in != NULL); |
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36 LTC_ARGCHK(out != NULL); |
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37 LTC_ARGCHK(outlen != NULL); |
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38 |
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39 /* packet must be at least 4 bytes */ |
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40 if (inlen < 4) { |
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41 return CRYPT_INVALID_ARG; |
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42 } |
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43 |
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44 /* check for 0x03 */ |
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45 if ((in[0]&0x1F) != 0x03) { |
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46 return CRYPT_INVALID_PACKET; |
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47 } |
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48 |
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49 /* offset in the data */ |
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50 x = 1; |
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51 |
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52 /* get the length of the data */ |
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53 if (in[x] & 0x80) { |
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54 /* long format get number of length bytes */ |
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55 y = in[x++] & 0x7F; |
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56 |
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57 /* invalid if 0 or > 2 */ |
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58 if (y == 0 || y > 2) { |
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59 return CRYPT_INVALID_PACKET; |
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60 } |
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61 |
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62 /* read the data len */ |
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63 dlen = 0; |
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64 while (y--) { |
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65 dlen = (dlen << 8) | (unsigned long)in[x++]; |
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66 } |
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67 } else { |
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68 /* short format */ |
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69 dlen = in[x++] & 0x7F; |
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70 } |
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71 |
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72 /* is the data len too long or too short? */ |
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73 if ((dlen == 0) || (dlen + x > inlen)) { |
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74 return CRYPT_INVALID_PACKET; |
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75 } |
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76 |
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77 /* get padding count */ |
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78 blen = ((dlen - 1) << 3) - (in[x++] & 7); |
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79 |
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80 /* too many bits? */ |
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81 if (blen > *outlen) { |
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82 *outlen = blen; |
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83 return CRYPT_BUFFER_OVERFLOW; |
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84 } |
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85 |
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86 /* decode/store the bits */ |
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87 for (y = 0; y < blen; y++) { |
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88 if (in[x] & (1 << (7 - (y & 7)))) { |
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89 SETBIT(out[y/8], 7-(y%8)); |
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90 } else { |
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91 CLRBIT(out[y/8], 7-(y%8)); |
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92 } |
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93 if ((y & 7) == 7) { |
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94 ++x; |
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95 } |
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96 } |
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97 |
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98 /* we done */ |
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99 *outlen = blen; |
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100 return CRYPT_OK; |
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101 } |
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102 |
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103 #endif |
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104 |
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105 /* ref: $Format:%D$ */ |
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106 /* git commit: $Format:%H$ */ |
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107 /* commit time: $Format:%ai$ */ |