Mercurial > dropbear
annotate libtomcrypt/src/encauth/ccm/ccm_add_aad.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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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 #ifdef LTC_CCM_MODE |
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12 |
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13 /** |
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14 Add AAD to the CCM state |
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15 @param ccm The CCM state |
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16 @param adata The additional authentication data to add to the CCM state |
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17 @param adatalen The length of the AAD data. |
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18 @return CRYPT_OK on success |
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19 */ |
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20 int ccm_add_aad(ccm_state *ccm, |
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21 const unsigned char *adata, unsigned long adatalen) |
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22 { |
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23 unsigned long y; |
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24 int err; |
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25 |
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26 LTC_ARGCHK(ccm != NULL); |
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27 LTC_ARGCHK(adata != NULL); |
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28 |
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29 if (ccm->aadlen < ccm->current_aadlen + adatalen) { |
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30 return CRYPT_INVALID_ARG; |
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31 } |
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32 ccm->current_aadlen += adatalen; |
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33 |
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34 /* now add the data */ |
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35 for (y = 0; y < adatalen; y++) { |
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36 if (ccm->x == 16) { |
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37 /* full block so let's encrypt it */ |
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38 if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->PAD, ccm->PAD, &ccm->K)) != CRYPT_OK) { |
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39 return err; |
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40 } |
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41 ccm->x = 0; |
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42 } |
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43 ccm->PAD[ccm->x++] ^= adata[y]; |
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44 } |
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45 |
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46 /* remainder? */ |
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47 if (ccm->aadlen == ccm->current_aadlen) { |
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48 if (ccm->x != 0) { |
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49 if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->PAD, ccm->PAD, &ccm->K)) != CRYPT_OK) { |
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50 return err; |
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51 } |
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52 } |
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53 ccm->x = 0; |
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54 } |
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55 |
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56 return CRYPT_OK; |
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57 } |
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58 |
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59 #endif |
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60 |
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61 /* ref: $Format:%D$ */ |
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62 /* git commit: $Format:%H$ */ |
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63 /* commit time: $Format:%ai$ */ |