Add support for fuzzing with AFL

Reviewed-by: Ben Laurie <ben@links.org>

MR: #2740

Configure

@@ -301,7 +301,8 @@ my @disablables = (
     "engine",
     "err",
     "filenames",
-    "fuzz",
+    "fuzz-libfuzzer",
+    "fuzz-afl",
     "gost",
     "heartbeats",
     "hw(-.+)?",
@@ -365,7 +366,8 @@ our %disabled = ( # "what"         => "comment"
                   "asan"		=> "default",
 		  "ec_nistp_64_gcc_128" => "default",
 		  "egd"                 => "default",
-		  "fuzz"		=> "default",
+		  "fuzz-libfuzzer"	=> "default",
+		  "fuzz-afl"		=> "default",
 		  "md2"                 => "default",
 		  "rc5"                 => "default",
 		  "sctp"                => "default",
@@ -698,6 +700,14 @@ foreach (@argvcopy)
 			{
 			$withargs{zlib_include}=$1;
 			}
+		elsif (/^--with-fuzzer-lib=(.*)$/)
+			{
+			$withargs{fuzzer_lib}=$1;
+			}
+		elsif (/^--with-fuzzer-include=(.*)$/)
+			{
+			$withargs{fuzzer_include}=$1;
+			}
 		elsif (/^--with-fipslibdir=(.*)$/)
 			{
 			$config{fipslibdir}="$1/";
@@ -1042,11 +1052,15 @@ if ($disabled{"dynamic-engine"}) {
         $config{dynamic_engines} = 1;
 }
 
-unless ($disabled{fuzz}) {
+unless ($disabled{"fuzz-libfuzzer"}) {
     push @{$config{dirs}}, "fuzz";
     $config{cflags} .= "-fsanitize-coverage=edge,indirect-calls ";
 }
 
+unless ($disabled{"fuzz-afl"}) {
+    push @{$config{dirs}}, "fuzz";
+}
+
 unless ($disabled{asan}) {
     $config{cflags} .= "-fsanitize=address ";
 }
@@ -1379,6 +1393,7 @@ if ($builder eq "unified") {
             $template->fill_in(HASH => { config => \%config,
                                          target => \%target,
                                          disabled => \%disabled,
+                                         withargs => \%withargs,
                                          builddir => abs2rel($buildd, $blddir),
                                          sourcedir => abs2rel($sourced, $blddir),
                                          buildtop => abs2rel($blddir, $blddir),

fuzz/README.md

@@ -1,5 +1,8 @@
 # I Can Haz Fuzz?
 
+LibFuzzer
+=========
+
 Or, how to fuzz OpenSSL with [libfuzzer](llvm.org/docs/LibFuzzer.html).
 
 Starting from a vanilla+OpenSSH server Ubuntu install.
@@ -32,7 +35,10 @@ https://github.com/llvm-mirror/llvm/tree/master/lib/Fuzzer if you prefer):
 
 Configure for fuzzing:
 
-    $ CC=clang ./config enable-fuzz enable-asan enable-ubsan no-shared
+    $ CC=clang ./config enable-fuzz-libfuzzer \
+            --with-fuzzer-include=../../svn-work/Fuzzer \
+            --with-fuzzer-lib=../../svn-work/Fuzzer/libFuzzer \
+            enable-asan enable-ubsan no-shared
     $ sudo apt-get install make
     $ LDCMD=clang++ make -j
     $ fuzz/helper.py <fuzzer> <arguments>
@@ -45,3 +51,20 @@ If you get a crash, you should find a corresponding input file in
 `fuzz/corpora/<fuzzer>-crash/`. You can reproduce the crash with
 
     $ fuzz/<fuzzer> <crashfile>
+
+AFL
+===
+
+Configure for fuzzing:
+
+    $ sudo apt-get install afl-clang
+    $ CC=afl-clang-fast ./config enable-fuzz-afl no-shared
+    $ make
+
+Run one of the fuzzers:
+
+    $ afl-fuzz fuzz/<fuzzer> -i fuzz/corpora/<fuzzer> -o fuzz/corpora/<fuzzer>/out <fuzzer> <arguments>
+
+Where `<fuzzer>` is one of the executables in `fuzz/`. Most fuzzers do not
+need any command line arguments, but, for example, `asn1` needs the name of a
+data type.

fuzz/asn1.c

@@ -60,7 +60,7 @@ static const ASN1_ITEM *item_type[] = {
     NULL
 };
 
-int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len) {
+int FuzzerTestOneInput(const uint8_t *buf, size_t len) {
     for (int n = 0; item_type[n] != NULL; ++n) {
         const uint8_t *b = buf;
         ASN1_VALUE *o = ASN1_item_d2i(NULL, &b, len, item_type[n]);

fuzz/asn1parse.c

@@ -18,7 +18,7 @@
 #include <openssl/x509v3.h>
 #include "fuzzer.h"
 
-int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len) {
+int FuzzerTestOneInput(const uint8_t *buf, size_t len) {
     static BIO *bio_out;
 
     if (bio_out == NULL)

fuzz/bignum.c

@@ -17,7 +17,7 @@
 #include <openssl/bn.h>
 #include "fuzzer.h"
 
-int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len) {
+int FuzzerTestOneInput(const uint8_t *buf, size_t len) {
     int success = 0;
     static BN_CTX *ctx;
     static BN_MONT_CTX *mont;

fuzz/bndiv.c

@@ -17,7 +17,7 @@
 #include <openssl/bn.h>
 #include "fuzzer.h"
 
-int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len) {
+int FuzzerTestOneInput(const uint8_t *buf, size_t len) {
     int success = 0;
     static BN_CTX *ctx;
     static BIGNUM *b1;

fuzz/build.info

@@ -1,33 +1,42 @@
+{- use File::Spec::Functions;
+   our $ex_inc = $withargs{fuzzer_include} &&
+       (file_name_is_absolute($withargs{fuzzer_include}) ?
+        $withargs{fuzzer_include} : catdir(updir(), $withargs{fuzzer_include}));
+   our $ex_lib = $withargs{fuzzer_lib} &&
+       (file_name_is_absolute($withargs{fuzzer_lib}) ?
+        $withargs{fuzzer_lib} : catfile(updir(), $withargs{fuzzer_lib}));
+   ""
+-}
 PROGRAMS=asn1 asn1parse bignum bndiv cms conf ct server
 
-SOURCE[asn1]=asn1.c
+SOURCE[asn1]=asn1.c driver.c
-INCLUDE[asn1]=../include ../../../svn-work/Fuzzer
+INCLUDE[asn1]=../include {- $ex_inc -}
-DEPEND[asn1]=../libcrypto ../../../svn-work/Fuzzer/libFuzzer
+DEPEND[asn1]=../libcrypto {- $ex_lib -}
 
-SOURCE[asn1parse]=asn1parse.c
+SOURCE[asn1parse]=asn1parse.c driver.c
-INCLUDE[asn1parse]=../include ../../../svn-work/Fuzzer
+INCLUDE[asn1parse]=../include {- $ex_inc -}
-DEPEND[asn1parse]=../libcrypto ../../../svn-work/Fuzzer/libFuzzer
+DEPEND[asn1parse]=../libcrypto {- $ex_lib -}
 
-SOURCE[bignum]=bignum.c
+SOURCE[bignum]=bignum.c driver.c
-INCLUDE[bignum]=../include ../../../svn-work/Fuzzer
+INCLUDE[bignum]=../include {- $ex_inc -}
-DEPEND[bignum]=../libcrypto ../../../svn-work/Fuzzer/libFuzzer
+DEPEND[bignum]=../libcrypto {- $ex_lib -}
 
-SOURCE[bndiv]=bndiv.c
+SOURCE[bndiv]=bndiv.c driver.c
-INCLUDE[bndiv]=../include ../../../svn-work/Fuzzer
+INCLUDE[bndiv]=../include {- $ex_inc -}
-DEPEND[bndiv]=../libcrypto ../../../svn-work/Fuzzer/libFuzzer
+DEPEND[bndiv]=../libcrypto {- $ex_lib -}
 
-SOURCE[cms]=cms.c
+SOURCE[cms]=cms.c driver.c
-INCLUDE[cms]=../include ../../../svn-work/Fuzzer
+INCLUDE[cms]=../include {- $ex_inc -}
-DEPEND[cms]=../libcrypto ../../../svn-work/Fuzzer/libFuzzer
+DEPEND[cms]=../libcrypto {- $ex_lib -}
 
-SOURCE[conf]=conf.c
+SOURCE[conf]=conf.c driver.c
-INCLUDE[conf]=../include ../../../svn-work/Fuzzer
+INCLUDE[conf]=../include {- $ex_inc -}
-DEPEND[conf]=../libcrypto ../../../svn-work/Fuzzer/libFuzzer
+DEPEND[conf]=../libcrypto {- $ex_lib -}
 
-SOURCE[ct]=ct.c
+SOURCE[ct]=ct.c driver.c
-INCLUDE[ct]=../include ../../../svn-work/Fuzzer
+INCLUDE[ct]=../include {- $ex_inc -}
-DEPEND[ct]=../libcrypto ../../../svn-work/Fuzzer/libFuzzer
+DEPEND[ct]=../libcrypto {- $ex_lib -}
 
-SOURCE[server]=server.c
+SOURCE[server]=server.c driver.c
-INCLUDE[server]=../include ../../../svn-work/Fuzzer
+INCLUDE[server]=../include {- $ex_inc -}
-DEPEND[server]=../libcrypto ../libssl ../../../svn-work/Fuzzer/libFuzzer
+DEPEND[server]=../libcrypto ../libssl {- $ex_lib -}

fuzz/cms.c

@@ -16,7 +16,7 @@
 #include <openssl/cms.h>
 #include "fuzzer.h"
 
-int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len) {
+int FuzzerTestOneInput(const uint8_t *buf, size_t len) {
     BIO *in = BIO_new(BIO_s_mem());
     OPENSSL_assert((size_t)BIO_write(in, buf, len) == len);
     CMS_ContentInfo *i = d2i_CMS_bio(in, NULL);

fuzz/conf.c

@@ -15,7 +15,7 @@
 #include <openssl/conf.h>
 #include "fuzzer.h"
 
-int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len) {
+int FuzzerTestOneInput(const uint8_t *buf, size_t len) {
     CONF *conf = NCONF_new(NULL);
     BIO *in = BIO_new(BIO_s_mem());
     long eline;

fuzz/ct.c

@@ -16,7 +16,7 @@
 #include <openssl/ct.h>
 #include "fuzzer.h"
 
-int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len) {
+int FuzzerTestOneInput(const uint8_t *buf, size_t len) {
     const uint8_t **pp = &buf;
     STACK_OF(SCT) *scts = d2i_SCT_LIST(NULL, pp, len);
     SCT_LIST_free(scts);

fuzz/driver.c

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the OpenSSL licenses, (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * https://www.openssl.org/source/license.html
+ * or in the file LICENSE in the source distribution.
+ */
+#include <stdint.h>
+#include <unistd.h>
+#include <openssl/opensslconf.h>
+#include "fuzzer.h"
+
+#ifndef OPENSSL_NO_FUZZ_LIBFUZZER
+
+int LLVMFuzzerInitialize(int *argc, char ***argv)
+{
+    if (FuzzerInitialize)
+        return FuzzerInitialize(argc, argv);
+    return 0;
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len) {
+    return FuzzerTestOneInput(buf, len);
+}
+
+#elif !defined(OPENSSL_NO_FUZZ_AFL)
+
+#define BUF_SIZE 65536
+
+int main(int argc, char** argv)
+{
+    if (FuzzerInitialize)
+        FuzzerInitialize(&argc, &argv);
+
+    while (__AFL_LOOP(10000)) {
+        uint8_t *buf = malloc(BUF_SIZE);
+        size_t size = read(0, buf, BUF_SIZE);
+
+        FuzzerTestOneInput(buf, size);
+        free(buf);
+    }
+    return 0;
+}
+
+#else
+
+#error "Unsupported fuzzer"
+
+#endif

fuzz/fuzzer.h

@@ -8,5 +8,5 @@
  * or in the file LICENSE in the source distribution.
  */
 
-int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len);
+int FuzzerTestOneInput(const uint8_t *buf, size_t len);
-int LLVMFuzzerInitialize(int *argc, char ***argv);
+__attribute__((weak)) int FuzzerInitialize(int *argc, char ***argv);

fuzz/server.c

@@ -208,7 +208,7 @@ static void Init() {
     X509_free(cert);
   }
 
-int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len) {
+int FuzzerTestOneInput(const uint8_t *buf, size_t len) {
     if (ctx == NULL)
         Init();
     // TODO: make this work for OpenSSL. There's a PREDICT define that may do