view fuzzer-verify.c @ 1653:76189c9ffea2

External Public-Key Authentication API (#72) * Implemented dynamic loading of an external plug-in shared library to delegate public key authentication * Moved conditional compilation of the plugin infrastructure into the configure.ac script to be able to add -ldl to dropbear build only when the flag is enabled * Added tags file to the ignore list * Updated API to have the constructor to return function pointers in the pliugin instance. Added support for passing user name to the checkpubkey function. Added options to the session returned by the plugin and have dropbear to parse and process them * Added -rdynamic to the linker flags when EPKA is enabled * Changed the API to pass a previously created session to the checkPubKey function (created during preauth) * Added documentation to the API * Added parameter addrstring to plugin creation function * Modified the API to retrieve the auth options. Instead of having them as field of the EPKASession struct, they are stored internally (plugin-dependent) in the plugin/session and retrieved through a pointer to a function (in the session) * Changed option string to be a simple char * instead of unsigned char *
author fabriziobertocci <fabriziobertocci@gmail.com>
date Wed, 15 May 2019 09:43:57 -0400
parents 92c93b4a3646
children f52919ffd3b1
line wrap: on
line source

#include "fuzz.h"
#include "session.h"
#include "fuzz-wrapfd.h"
#include "debug.h"

static void setup_fuzzer(void) {
	fuzz_common_setup();
}

static buffer *verifydata;

/* Tests reading a public key and verifying a signature */
int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
	static int once = 0;
	if (!once) {
		setup_fuzzer();
		verifydata = buf_new(30);
		buf_putstring(verifydata, "x", 1);
		once = 1;
	}

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

	m_malloc_set_epoch(1);

	if (setjmp(fuzz.jmp) == 0) {
		sign_key *key = new_sign_key();
		enum signkey_type type = DROPBEAR_SIGNKEY_ANY;
		if (buf_get_pub_key(fuzz.input, key, &type) == DROPBEAR_SUCCESS) {
			if (buf_verify(fuzz.input, key, verifydata) == DROPBEAR_SUCCESS) {
				/* The fuzzer is capable of generating keys with a signature to match.
				We don't want false positives if the key is bogus, since a client/server 
				wouldn't be trusting a bogus key anyway */
				int boguskey = 0;

				if (type == DROPBEAR_SIGNKEY_DSS) {
					/* So far have seen dss keys with bad p/q/g domain parameters */
					int pprime, qprime;
				    assert(mp_prime_is_prime(key->dsskey->p, 5, &pprime) == MP_OKAY);
				    assert(mp_prime_is_prime(key->dsskey->q, 18, &qprime) == MP_OKAY);
				    boguskey = !(pprime && qprime);
				    /* Could also check g**q mod p == 1 */
				}

				if (!boguskey) {
					printf("Random key/signature managed to verify!\n");
					abort();
				}


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

	return 0;
}