view fuzzer-kexcurve25519.c @ 1659:d32bcb5c557d

Add Ed25519 support (#91) * Add support for Ed25519 as a public key type Ed25519 is a elliptic curve signature scheme that offers better security than ECDSA and DSA and good performance. It may be used for both user and host keys. OpenSSH key import and fuzzer are not supported yet. Initially inspired by Peter Szabo. * Add curve25519 and ed25519 fuzzers * Add import and export of Ed25519 keys
author Vladislav Grishenko <themiron@users.noreply.github.com>
date Wed, 11 Mar 2020 21:09:45 +0500
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#include "fuzz.h"
#include "session.h"
#include "fuzz-wrapfd.h"
#include "debug.h"
#include "runopts.h"
#include "algo.h"
#include "bignum.h"

int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
	static int once = 0;
	static struct key_context* keep_newkeys = NULL;
	/* number of generated parameters is limited by the timeout for the first run.
	   TODO move this to the libfuzzer initialiser function instead if the timeout
	   doesn't apply there */
	#define NUM_PARAMS 20
	static struct kex_curve25519_param *curve25519_params[NUM_PARAMS];

	if (!once) {
		fuzz_common_setup();
		fuzz_svr_setup();

		keep_newkeys = (struct key_context*)m_malloc(sizeof(struct key_context));
		keep_newkeys->algo_kex = fuzz_get_algo(sshkex, "curve25519-sha256");
		keep_newkeys->algo_hostkey = DROPBEAR_SIGNKEY_ED25519;
		ses.newkeys = keep_newkeys;

		/* Pre-generate parameters */
		int i;
		for (i = 0; i < NUM_PARAMS; i++) {
			curve25519_params[i] = gen_kexcurve25519_param();
		}

		once = 1;
	}

	if (fuzz_set_input(Data, Size) == DROPBEAR_FAILURE) {
		return 0;
	}

	m_malloc_set_epoch(1);

	if (setjmp(fuzz.jmp) == 0) {
		/* Based on recv_msg_kexdh_init()/send_msg_kexdh_reply() 
		with DROPBEAR_KEX_CURVE25519 */
		ses.newkeys = keep_newkeys;

		/* Choose from the collection of curve25519 params */
		unsigned int e = buf_getint(fuzz.input);
		struct kex_curve25519_param *curve25519_param = curve25519_params[e % NUM_PARAMS];

		buffer * ecdh_qs = buf_getstringbuf(fuzz.input);

		ses.kexhashbuf = buf_new(KEXHASHBUF_MAX_INTS);
		kexcurve25519_comb_key(curve25519_param, ecdh_qs, svr_opts.hostkey);

		mp_clear(ses.dh_K);
		m_free(ses.dh_K);
		buf_free(ecdh_qs);

		buf_free(ses.hash);
		buf_free(ses.session_id);
		/* kexhashbuf is freed in kexdh_comb_key */

		m_malloc_free_epoch(1, 0);
	} else {
		m_malloc_free_epoch(1, 1);
		TRACE(("dropbear_exit longjmped"))
		/* dropbear_exit jumped here */
	}

	return 0;
}