Mercurial > dropbear
annotate libtomcrypt/src/pk/asn1/der/printable_string/der_encode_printable_string.c @ 1715:3974f087d9c0
Disallow leading lines before the ident for server (#102)
Per RFC4253 4.2 clients must be able to process other lines of data
before the version string, server behavior is not defined neither
with MUST/SHOULD nor with MAY.
If server process up to 50 lines too - it may cause too long hanging
session with invalid/evil client that consume host resources and
potentially may lead to DDoS on poor embedded boxes.
Let's require first line from client to be version string and fail
early if it's not - matches both RFC and real OpenSSH behavior.
author | Vladislav Grishenko <themiron@users.noreply.github.com> |
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date | Mon, 15 Jun 2020 18:22:18 +0500 |
parents | 6dba84798cd5 |
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rev | line source |
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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_printable_string.c |
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13 ASN.1 DER, encode a printable STRING, Tom St Denis |
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14 */ |
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15 |
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16 #ifdef LTC_DER |
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17 |
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18 /** |
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19 Store an printable STRING |
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20 @param in The array of printable to store (one per char) |
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21 @param inlen The number of printable to store |
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22 @param out [out] The destination for the DER encoded printable STRING |
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23 @param outlen [in/out] The max size and resulting size of the DER printable STRING |
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24 @return CRYPT_OK if successful |
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25 */ |
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26 int der_encode_printable_string(const unsigned char *in, unsigned long inlen, |
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27 unsigned char *out, unsigned long *outlen) |
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28 { |
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29 unsigned long x, y, len; |
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30 int err; |
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31 |
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32 LTC_ARGCHK(in != NULL); |
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33 LTC_ARGCHK(out != NULL); |
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34 LTC_ARGCHK(outlen != NULL); |
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35 |
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36 /* get the size */ |
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37 if ((err = der_length_printable_string(in, inlen, &len)) != CRYPT_OK) { |
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38 return err; |
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39 } |
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40 |
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41 /* too big? */ |
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42 if (len > *outlen) { |
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43 *outlen = len; |
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44 return CRYPT_BUFFER_OVERFLOW; |
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45 } |
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46 |
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47 /* encode the header+len */ |
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48 x = 0; |
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49 out[x++] = 0x13; |
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50 if (inlen < 128) { |
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51 out[x++] = (unsigned char)inlen; |
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52 } else if (inlen < 256) { |
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53 out[x++] = 0x81; |
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54 out[x++] = (unsigned char)inlen; |
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55 } else if (inlen < 65536UL) { |
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56 out[x++] = 0x82; |
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57 out[x++] = (unsigned char)((inlen>>8)&255); |
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58 out[x++] = (unsigned char)(inlen&255); |
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59 } else if (inlen < 16777216UL) { |
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60 out[x++] = 0x83; |
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61 out[x++] = (unsigned char)((inlen>>16)&255); |
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62 out[x++] = (unsigned char)((inlen>>8)&255); |
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63 out[x++] = (unsigned char)(inlen&255); |
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64 } else { |
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65 return CRYPT_INVALID_ARG; |
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66 } |
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67 |
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68 /* store octets */ |
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69 for (y = 0; y < inlen; y++) { |
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70 out[x++] = der_printable_char_encode(in[y]); |
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71 } |
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72 |
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73 /* retun length */ |
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74 *outlen = x; |
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75 |
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76 return CRYPT_OK; |
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77 } |
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78 |
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79 #endif |
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80 |
1471
6dba84798cd5
Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
1435
diff
changeset
|
81 /* ref: $Format:%D$ */ |
6dba84798cd5
Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
1435
diff
changeset
|
82 /* git commit: $Format:%H$ */ |
6dba84798cd5
Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
1435
diff
changeset
|
83 /* commit time: $Format:%ai$ */ |