src: move fuzzer functionality to separate tool

This means some loss of functionality since you can no longer combine
--fuzzer with options like --debug, --define, --include.

On the upside, this adds new --random-outflags mode which will randomly
switch --terse, --numeric, --echo ... on/off.

Update README to reflect this change.

Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>

2 files changed, 0 insertions, 316 deletions

diff --git a/src/afl++.c b/src/afl++.c
deleted file mode 100644
index 79925952..00000000
--- a/src/afl++.c
+++ /dev/null
@@ -1,219 +0,0 @@
-/*
- * Copyright (c) Red Hat GmbH.	Author: Florian Westphal <fw@strlen.de>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 (or any
- * later) as published by the Free Software Foundation.
- */
-
-#include <nft.h>
-#include <stdio.h>
-
-#include <errno.h>
-#include <ctype.h>
-#include <limits.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <time.h>
-
-#include <sys/stat.h>
-#include <sys/wait.h>
-
-#include <afl++.h>
-#include <nftables.h>
-
-static const char self_fault_inject_file[] = "/proc/self/make-it-fail";
-
-#ifdef __AFL_FUZZ_TESTCASE_LEN
-/* the below macro gets passed via afl-cc, declares prototypes
- * depending on the afl-cc flavor.
- */
-__AFL_FUZZ_INIT();
-#else
-/* this lets the source compile without afl-clang-fast/lto */
-static unsigned char fuzz_buf[4096];
-static ssize_t fuzz_len;
-
-#define __AFL_FUZZ_TESTCASE_LEN fuzz_len
-#define __AFL_FUZZ_TESTCASE_BUF fuzz_buf
-#define __AFL_FUZZ_INIT() do { } while (0)
-#define __AFL_LOOP(x) \
-   ((fuzz_len = read(0, fuzz_buf, sizeof(fuzz_buf))) > 0 ? 1 : 0)
-#endif
-
-struct nft_afl_state {
-	FILE *make_it_fail_fp;
-};
-
-static struct nft_afl_state state;
-
-static char *preprocess(unsigned char *input, ssize_t len)
-{
-	ssize_t real_len = strnlen((char *)input, len);
-
-	if (real_len == 0)
-		return NULL;
-
-	if (real_len >= len)
-		input[len - 1] = 0;
-
-	return (char *)input;
-}
-
-static bool kernel_is_tainted(void)
-{
-	FILE *fp = fopen("/proc/sys/kernel/tainted", "r");
-	unsigned int taint;
-	bool ret = false;
-
-	if (fp) {
-		if (fscanf(fp, "%u", &taint) == 1 && taint) {
-			fprintf(stderr, "Kernel is tainted: 0x%x\n", taint);
-			sleep(3);	/* in case we run under fuzzer, don't restart right away */
-			ret = true;
-		}
-
-		fclose(fp);
-	}
-
-	return ret;
-}
-
-static void fault_inject_write(FILE *fp, unsigned int v)
-{
-	rewind(fp);
-	fprintf(fp, "%u\n", v);
-	fflush(fp);
-}
-
-static void fault_inject_enable(const struct nft_afl_state *state)
-{
-	if (state->make_it_fail_fp)
-		fault_inject_write(state->make_it_fail_fp, 1);
-}
-
-static void fault_inject_disable(const struct nft_afl_state *state)
-{
-	if (state->make_it_fail_fp)
-		fault_inject_write(state->make_it_fail_fp, 0);
-}
-
-static bool nft_afl_run_cmd(struct nft_ctx *ctx, const char *input_cmd)
-{
-	if (kernel_is_tainted())
-		return false;
-
-	switch (ctx->afl_ctx_stage) {
-	case NFT_AFL_FUZZER_PARSER:
-	case NFT_AFL_FUZZER_EVALUATION:
-	case NFT_AFL_FUZZER_NETLINK_RO:
-		nft_run_cmd_from_buffer(ctx, input_cmd);
-		return true;
-	case NFT_AFL_FUZZER_NETLINK_RW:
-		break;
-	}
-
-	fault_inject_enable(&state);
-	nft_run_cmd_from_buffer(ctx, input_cmd);
-	fault_inject_disable(&state);
-
-	return kernel_is_tainted();
-}
-
-static FILE *fault_inject_open(void)
-{
-	return fopen(self_fault_inject_file, "r+");
-}
-
-static bool nft_afl_state_init(struct nft_afl_state *state)
-{
-	state->make_it_fail_fp = fault_inject_open();
-	return true;
-}
-
-int nft_afl_init(struct nft_ctx *ctx, enum nft_afl_fuzzer_stage stage)
-{
-#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
-	const char instrumented[] = "afl instrumented";
-#else
-	const char instrumented[] = "no afl instrumentation";
-#endif
-	nft_afl_print_build_info(stderr);
-
-	if (!nft_afl_state_init(&state))
-		return -1;
-
-	ctx->afl_ctx_stage = stage;
-
-	if (state.make_it_fail_fp) {
-		unsigned int value;
-		int ret;
-
-		rewind(state.make_it_fail_fp);
-		ret = fscanf(state.make_it_fail_fp, "%u", &value);
-		if (ret != 1 || value != 1) {
-			fclose(state.make_it_fail_fp);
-			state.make_it_fail_fp = NULL;
-		}
-
-		/* if its enabled, disable and then re-enable ONLY
-		 * when submitting data to the kernel.
-		 *
-		 * Otherwise even libnftables memory allocations could fail
-		 * which is not what we want.
-		 */
-		fault_inject_disable(&state);
-	}
-
-	fprintf(stderr, "starting (%s, %s fault injection)", instrumented, state.make_it_fail_fp ? "with" : "no");
-	return 0;
-}
-
-int nft_afl_main(struct nft_ctx *ctx)
-{
-	unsigned char *buf;
-	ssize_t len;
-
-	if (kernel_is_tainted())
-		return -1;
-
-	if (state.make_it_fail_fp) {
-		FILE *fp = fault_inject_open();
-
-		/* reopen is needed because /proc/self is a symlink, i.e.
-		 * fp refers to parent process, not "us".
-		 */
-		if (!fp) {
-			fprintf(stderr, "Could not reopen %s: %s", self_fault_inject_file, strerror(errno));
-			return -1;
-		}
-
-		fclose(state.make_it_fail_fp);
-		state.make_it_fail_fp = fp;
-	}
-
-	buf = __AFL_FUZZ_TESTCASE_BUF;
-
-	while (__AFL_LOOP(UINT_MAX)) {
-		char *input;
-
-		len = __AFL_FUZZ_TESTCASE_LEN;  // do not use the macro directly in a call!
-
-		input = preprocess(buf, len);
-		if (!input)
-			continue;
-
-		/* buf is null terminated at this point */
-		if (!nft_afl_run_cmd(ctx, input))
-			continue;
-
-		/* Kernel is tainted.
-		 * exit() will cause a restart from afl-fuzz.
-		 * Avoid burning cpu cycles in this case.
-		 */
-		sleep(1);
-	}
-
-	/* afl-fuzz will restart us. */
-	return 0;
-}
diff --git a/src/main.c b/src/main.c
index c2e909d2..29b0533d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -21,7 +21,6 @@
 #include <nftables/libnftables.h>
 #include <utils.h>
 #include <cli.h>
-#include <afl++.h>
 
 static struct nft_ctx *nft;
 
@@ -87,11 +86,6 @@ enum opt_vals {
 	OPT_TERSE		= 't',
 	OPT_OPTIMIZE		= 'o',
 	OPT_INVALID		= '?',
-
-#if HAVE_FUZZER_BUILD
-	/* keep last */
-        OPT_FUZZER		= 254
-#endif
 };
 
 struct nft_opt {
@@ -149,10 +143,6 @@ static const struct nft_opt nft_options[] = {
 				     "Specify debugging level (scanner, parser, eval, netlink, mnl, proto-ctx, segtree, all)"),
 	[IDX_OPTIMIZE]	    = NFT_OPT("optimize",		OPT_OPTIMIZE,		NULL,
 				     "Optimize ruleset"),
-#if HAVE_FUZZER_BUILD
-	[IDX_FUZZER]	    = NFT_OPT("fuzzer",			OPT_FUZZER,		"stage",
-				      "fuzzer stage to run (parser, eval, netlink-ro, netlink-rw)"),
-#endif
 };
 
 #define NR_NFT_OPTIONS (sizeof(nft_options) / sizeof(nft_options[0]))
@@ -243,7 +233,6 @@ static void show_help(const char *name)
 		print_option(&nft_options[i]);
 
 	fputs("\n", stdout);
-	nft_afl_print_build_info(stdout);
 }
 
 static void show_version(void)
@@ -286,7 +275,6 @@ static void show_version(void)
 	       PACKAGE_NAME, PACKAGE_VERSION, RELEASE_NAME,
 	       cli, json, minigmp, xt);
 
-	nft_afl_print_build_info(stdout);
 }
 
 static const struct {
@@ -327,38 +315,6 @@ static const struct {
 	},
 };
 
-#if HAVE_FUZZER_BUILD
-static const struct {
-	const char			*name;
-	enum nft_afl_fuzzer_stage	stage;
-} fuzzer_stage_param[] = {
-	{
-		.name		= "parser",
-		.stage		= NFT_AFL_FUZZER_PARSER,
-	},
-	{
-		.name		= "eval",
-		.stage		= NFT_AFL_FUZZER_EVALUATION,
-	},
-	{
-		.name		= "netlink-ro",
-		.stage		= NFT_AFL_FUZZER_NETLINK_RO,
-	},
-	{
-		.name		= "netlink-rw",
-		.stage		= NFT_AFL_FUZZER_NETLINK_RW,
-	},
-};
-static void afl_exit(const char *err)
-{
-	fprintf(stderr, "Error: fuzzer: %s\n", err);
-	sleep(60);	/* assume we're running under afl-fuzz and would be restarted right away */
-	exit(EXIT_FAILURE);
-}
-#else
-static inline void afl_exit(const char *err) { }
-#endif
-
 static void nft_options_error(int argc, char * const argv[], int pos)
 {
 	int i;
@@ -407,7 +363,6 @@ static bool nft_options_check(int argc, char * const argv[])
 int main(int argc, char * const *argv)
 {
 	const struct option *options = get_options();
-	enum nft_afl_fuzzer_stage fuzzer_stage = 0;
 	bool interactive = false, define = false;
 	const char *optstring = get_optstring();
 	unsigned int output_flags = 0;
@@ -549,26 +504,6 @@ int main(int argc, char * const *argv)
 		case OPT_OPTIMIZE:
 			nft_ctx_set_optimize(nft, 0x1);
 			break;
-#if HAVE_FUZZER_BUILD
-		case OPT_FUZZER:
-			{
-				unsigned int i;
-
-				for (i = 0; i < array_size(fuzzer_stage_param); i++) {
-					if (strcmp(fuzzer_stage_param[i].name, optarg))
-						continue;
-					fuzzer_stage = fuzzer_stage_param[i].stage;
-					break;
-				}
-
-				if (i == array_size(fuzzer_stage_param)) {
-					fprintf(stderr, "invalid fuzzer stage `%s'\n",
-						optarg);
-					goto out_fail;
-				}
-			}
-			break;
-#endif
 		case OPT_INVALID:
 			goto out_fail;
 		}
@@ -581,38 +516,6 @@ int main(int argc, char * const *argv)
 
 	nft_ctx_output_set_flags(nft, output_flags);
 
-	if (fuzzer_stage) {
-		unsigned int input_flags;
-
-		if (filename || define || interactive)
-			afl_exit("-D/--define, -f/--filename and -i/--interactive are incompatible options");
-
-		rc = nft_afl_init(nft, fuzzer_stage);
-		if (rc != 0)
-			afl_exit("cannot initialize");
-
-		input_flags = nft_ctx_input_get_flags(nft);
-
-		/* DNS lookups can result in severe fuzzer slowdown */
-		input_flags |= NFT_CTX_INPUT_NO_DNS;
-		nft_ctx_input_set_flags(nft, input_flags);
-
-		if (fuzzer_stage < NFT_AFL_FUZZER_NETLINK_RW)
-			nft_ctx_set_dry_run(nft, true);
-
-		fprintf(stderr, "Awaiting fuzzer-generated inputs\n");
-	}
-
-	__AFL_INIT();
-
-	if (fuzzer_stage) {
-		rc = nft_afl_main(nft);
-		if (rc != 0)
-			afl_exit("fatal error");
-
-		return EXIT_SUCCESS;
-	}
-
 	if (optind != argc) {
 		char *buf;