Mercurial > dropbear
view libtomcrypt/src/mac/f9/f9_process.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> |
---|---|
date | Mon, 15 Jun 2020 18:22:18 +0500 |
parents | 6dba84798cd5 |
children |
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis * * LibTomCrypt is a library that provides various cryptographic * algorithms in a highly modular and flexible manner. * * The library is free for all purposes without any express * guarantee it works. */ #include "tomcrypt.h" /** @file f9_process.c f9 Support, process blocks with f9 */ #ifdef LTC_F9_MODE /** Process data through f9-MAC @param f9 The f9-MAC state @param in Input data to process @param inlen Length of input in octets Return CRYPT_OK on success */ int f9_process(f9_state *f9, const unsigned char *in, unsigned long inlen) { int err, x; LTC_ARGCHK(f9 != NULL); LTC_ARGCHK(in != NULL); /* check structure */ if ((err = cipher_is_valid(f9->cipher)) != CRYPT_OK) { return err; } if ((f9->blocksize > cipher_descriptor[f9->cipher].block_length) || (f9->blocksize < 0) || (f9->buflen > f9->blocksize) || (f9->buflen < 0)) { return CRYPT_INVALID_ARG; } #ifdef LTC_FAST if (f9->buflen == 0) { while (inlen >= (unsigned long)f9->blocksize) { for (x = 0; x < f9->blocksize; x += sizeof(LTC_FAST_TYPE)) { *(LTC_FAST_TYPE_PTR_CAST(&(f9->IV[x]))) ^= *(LTC_FAST_TYPE_PTR_CAST(&(in[x]))); } cipher_descriptor[f9->cipher].ecb_encrypt(f9->IV, f9->IV, &f9->key); for (x = 0; x < f9->blocksize; x += sizeof(LTC_FAST_TYPE)) { *(LTC_FAST_TYPE_PTR_CAST(&(f9->ACC[x]))) ^= *(LTC_FAST_TYPE_PTR_CAST(&(f9->IV[x]))); } in += f9->blocksize; inlen -= f9->blocksize; } } #endif while (inlen) { if (f9->buflen == f9->blocksize) { cipher_descriptor[f9->cipher].ecb_encrypt(f9->IV, f9->IV, &f9->key); for (x = 0; x < f9->blocksize; x++) { f9->ACC[x] ^= f9->IV[x]; } f9->buflen = 0; } f9->IV[f9->buflen++] ^= *in++; --inlen; } return CRYPT_OK; } #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */