view crypto_desc.c @ 1861:2b3a8026a6ce

Add re-exec for server This allows ASLR to re-randomize the address space for every connection, preventing some vulnerabilities from being exploitable by repeated probing. Overhead (memory and time) is yet to be confirmed. At present this is only enabled on Linux. Other BSD platforms with fexecve() would probably also work though have not been tested.
author Matt Johnston <matt@ucc.asn.au>
date Sun, 30 Jan 2022 10:14:56 +0800
parents 34d9d3c022ce
children 13cb8cc1b0e4
line wrap: on
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#include "includes.h"
#include "dbutil.h"
#include "crypto_desc.h"
#include "ltc_prng.h"
#include "ecc.h"
#include "dbrandom.h"

#if DROPBEAR_LTC_PRNG
	int dropbear_ltc_prng = -1;
#endif

/* Wrapper for libtommath */
static mp_err dropbear_rand_source(void* out, size_t size) {
	genrandom((unsigned char*)out, (unsigned int)size);
	return MP_OKAY;
}


/* Register the compiled in ciphers.
 * This should be run before using any of the ciphers/hashes */
void crypto_init() {

	const struct ltc_cipher_descriptor *regciphers[] = {
#if DROPBEAR_AES
		&aes_desc,
#endif
#if DROPBEAR_BLOWFISH
		&blowfish_desc,
#endif
#if DROPBEAR_TWOFISH
		&twofish_desc,
#endif
#if DROPBEAR_3DES
		&des3_desc,
#endif
		NULL
	};

	const struct ltc_hash_descriptor *reghashes[] = {
		/* we need sha1 for hostkey stuff regardless */
		&sha1_desc,
#if DROPBEAR_MD5_HMAC
		&md5_desc,
#endif
#if DROPBEAR_SHA256
		&sha256_desc,
#endif
#if DROPBEAR_SHA384
		&sha384_desc,
#endif
#if DROPBEAR_SHA512
		&sha512_desc,
#endif
		NULL
	};	
	int i;
	
	for (i = 0; regciphers[i] != NULL; i++) {
		if (register_cipher(regciphers[i]) == -1) {
			dropbear_exit("Error registering crypto");
		}
	}

	for (i = 0; reghashes[i] != NULL; i++) {
		if (register_hash(reghashes[i]) == -1) {
			dropbear_exit("Error registering crypto");
		}
	}

#if DROPBEAR_LTC_PRNG
	dropbear_ltc_prng = register_prng(&dropbear_prng_desc);
	if (dropbear_ltc_prng == -1) {
		dropbear_exit("Error registering crypto");
	}
#endif

	mp_rand_source(dropbear_rand_source);

#if DROPBEAR_ECC
	ltc_mp = ltm_desc;
	dropbear_ecc_fill_dp();
#endif
}