view fuzzer-pubkey.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 ba6fc7afe1c5
children
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();
}

int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
	static int once = 0;
	if (!once) {
		setup_fuzzer();
		once = 1;
	}

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

	m_malloc_set_epoch(1);

	if (setjmp(fuzz.jmp) == 0) {
		buffer *line = buf_getstringbuf(fuzz.input);
		buffer *keyblob = buf_getstringbuf(fuzz.input);

		unsigned int algolen;
		char* algoname = buf_getstring(keyblob, &algolen);

		if (signature_type_from_name(algoname, algolen) == DROPBEAR_SIGNKEY_NONE) {
			dropbear_exit("fuzzer imagined a bogus algorithm");
		}

		int ret = fuzz_checkpubkey_line(line, 5, "/home/me/authorized_keys",
			algoname, algolen,
			keyblob->data, keyblob->len);

		if (ret == DROPBEAR_SUCCESS) {
			/* fuzz_checkpubkey_line() should have cleaned up for failure */
			svr_pubkey_options_cleanup();
		}

		buf_free(line);
		buf_free(keyblob);
		m_free(algoname);
		m_malloc_free_epoch(1, 0);
	} else {
		m_malloc_free_epoch(1, 1);
		TRACE(("dropbear_exit longjmped"))
		/* dropbear_exit jumped here */
	}

	return 0;
}