From 0f0ce2af37cfde65e05f04a5277252fe47e6f457 Mon Sep 17 00:00:00 2001
From: Vincent Batts <vbatts@hashbangbash.com>
Date: Wed, 6 Jun 2018 10:42:39 -0400
Subject: [PATCH] switching to plugins

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>
---
 .gitignore                          |  3 +++
 Makefile                            | 15 ++++++++---
 main.go                             | 37 +++----------------------
 walker/func.go                      | 15 ++++++-----
 walker/walkers/readFuzz/readFuzz.go | 42 +++++++++++++++++++++++++++++
 5 files changed, 70 insertions(+), 42 deletions(-)
 create mode 100644 .gitignore
 create mode 100644 walker/walkers/readFuzz/readFuzz.go

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..42f6449
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+fuzz-walker
+plugin-*.so
+*~
diff --git a/Makefile b/Makefile
index 1522154..eb942b3 100644
--- a/Makefile
+++ b/Makefile
@@ -1,10 +1,19 @@
 
-GO := go
+GO ?= go
+SOURCE_FILES := \
+	$(wildcard *.go) \
+	$(wildcard walker/*.go) \
+	$(wildcard walker/walkers/*/*.go)
+PLUGINS := \
+	plugin-readFuzz.so
 
-default: fuzz-walker
+default: fuzz-walker $(PLUGINS)
 
 fuzz-walker: $(wildcard *.go)
 	$(GO) build -o $@ .
 
+plugin-%.so:
+	$(GO) build -o $@ -buildmode=plugin ./walker/walkers/$*/
+
 clean:
-	rm -f fuzz-walker
+	rm -f fuzz-walker *.so
diff --git a/main.go b/main.go
index cf0ad24..fa5f50e 100644
--- a/main.go
+++ b/main.go
@@ -2,8 +2,6 @@ package main
 
 import (
 	"fmt"
-	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"time"
@@ -14,13 +12,7 @@ import (
 )
 
 var (
-	dirs   = []string{"/sys", "/proc"}
-	fuzzes = map[string]walker.FuzzFunc{
-		"chmod":      chmodFuzz,
-		"read":       readFuzz,
-		"writeBytes": writeBytesFuzz,
-		"writeNum":   writeNumFuzz,
-	}
+	dirs          = []string{"/sys", "/proc"}
 	fuzzTimeout   = 500 * time.Millisecond
 	walkerPlugins []walker.Fuzzer
 )
@@ -62,9 +54,9 @@ func main() {
 				if !info.Mode().IsRegular() {
 					return nil
 				}
-				for fname, fuzz := range fuzzes {
-					if err := fuzz(path, info, fuzzTimeout); err != nil {
-						logrus.Warnf("%s: %q fuzz failed with: %v", path, fname, err)
+				for _, wp := range walkerPlugins {
+					if err := wp.Func(path, info, fuzzTimeout); err != nil {
+						logrus.Warnf("%s: %q fuzz failed with: %v", path, wp.Name(), err)
 					}
 				}
 				return nil
@@ -83,27 +75,6 @@ func main() {
 	app.Run(os.Args)
 }
 
-func readFuzz(path string, info os.FileInfo, timeout time.Duration) error {
-	c1 := make(chan error, 1)
-	go func() {
-		fd, err := os.Open(path)
-		if err != nil {
-			c1 <- err
-		}
-		defer fd.Close()
-		_, err = io.Copy(ioutil.Discard, fd)
-		c1 <- err
-	}()
-
-	select {
-	case err := <-c1:
-		return err
-	case <-time.After(timeout):
-		return fmt.Errorf("timeout reached")
-	}
-	return nil
-}
-
 func writeNumFuzz(path string, info os.FileInfo, timeout time.Duration) error {
 	return nil
 }
diff --git a/walker/func.go b/walker/func.go
index 3795255..95d2124 100644
--- a/walker/func.go
+++ b/walker/func.go
@@ -13,21 +13,24 @@ func LoadPlugin(path string) (Fuzzer, error) {
 	if err != nil {
 		return nil, err
 	}
-	sym, err := p.Lookup("MyFuzzerFunc")
+	sym, err := p.Lookup("NewFuzzer")
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("LoadPlugin: %q", err)
 	}
-	mff, ok := sym.(Fuzzer)
+	nf, ok := sym.(func() (Fuzzer, error))
 	if !ok {
-		return nil, fmt.Errorf("plugin at %q did not provide a FuzzFunc named MyFuzzerFunc", path)
+		return nil, fmt.Errorf("LoadPlugin: plugin at %q did not provide a NewFuzzer function", path)
 	}
-	return mff, nil
+	return nf()
 }
 
+// NewFuzzer initializes a new Fuzzer
+type NewFuzzer func() (Fuzzer, error)
+
 // Fuzzer is a struct that produces a FuzzFunc
 type Fuzzer interface {
 	Name() string
-	Func() FuzzFunc
+	Func(path string, info os.FileInfo, timeout time.Duration) error
 }
 
 // FuzzFunc is like filepath.WalkerFunc, but for poking at `path`
diff --git a/walker/walkers/readFuzz/readFuzz.go b/walker/walkers/readFuzz/readFuzz.go
new file mode 100644
index 0000000..e5b0943
--- /dev/null
+++ b/walker/walkers/readFuzz/readFuzz.go
@@ -0,0 +1,42 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"time"
+
+	"git.thisco.de/vbatts/fuzz-walker/walker"
+)
+
+func NewFuzzer() (walker.Fuzzer, error) {
+	return &myFuzzer{}, nil
+}
+
+type myFuzzer struct{}
+
+func (mf myFuzzer) Name() string {
+	return "readFuzz"
+}
+
+func (mf myFuzzer) Func(path string, info os.FileInfo, timeout time.Duration) error {
+	c1 := make(chan error, 1)
+	go func() {
+		fd, err := os.Open(path)
+		if err != nil {
+			c1 <- err
+		}
+		defer fd.Close()
+		_, err = io.Copy(ioutil.Discard, fd)
+		c1 <- err
+	}()
+
+	select {
+	case err := <-c1:
+		return err
+	case <-time.After(timeout):
+		return fmt.Errorf("timeout reached")
+	}
+	return nil
+}