better error handling for static files handler

go.mod

@@ -0,0 +1,11 @@
+module github.com/foomo/gofoomo
+
+go 1.14
+
+require (
+	github.com/abbot/go-http-auth v0.4.0
+	github.com/bgentry/speakeasy v0.1.0
+	github.com/foomo/htpasswd v0.0.0-20200116085101-e3a90e78da9c
+	github.com/foomo/tlsconfig v0.0.0-20180418120404-b67861b076c9
+	gopkg.in/yaml.v2 v2.3.0
+)

go.sum

@@ -0,0 +1,22 @@
+github.com/GehirnInc/crypt v0.0.0-20190301055215-6c0105aabd46 h1:rs0kDBt2zF4/CM9rO5/iH+U22jnTygPlqWgX55Ufcxg=
+github.com/GehirnInc/crypt v0.0.0-20190301055215-6c0105aabd46/go.mod h1:kC29dT1vFpj7py2OvG1khBdQpo3kInWP+6QipLbdngo=
+github.com/abbot/go-http-auth v0.4.0 h1:QjmvZ5gSC7jm3Zg54DqWE/T5m1t2AfDu6QlXJT0EVT0=
+github.com/abbot/go-http-auth v0.4.0/go.mod h1:Cz6ARTIzApMJDzh5bRMSUou6UMSp0IEXg9km/ci7TJM=
+github.com/bgentry/speakeasy v0.1.0 h1:ByYyxL9InA1OWqxJqqp2A5pYHUrCiAL6K3J+LKSsQkY=
+github.com/bgentry/speakeasy v0.1.0/go.mod h1:+zsyZBPWlz7T6j88CTgSN5bM796AkVf0kBD4zp0CCIs=
+github.com/foomo/htpasswd v0.0.0-20200116085101-e3a90e78da9c h1:DBGU7zCwrrPPDsD6+gqKG8UfMxenWg9BOJE/Nmfph+4=
+github.com/foomo/htpasswd v0.0.0-20200116085101-e3a90e78da9c/go.mod h1:SHawtolbB0ZOFoRWgDwakX5WpwuIWAK88bUXVZqK0Ss=
+github.com/foomo/tlsconfig v0.0.0-20180418120404-b67861b076c9 h1:RPOsDNbnDUFaSt/3bCxUsaGCJsKqA6dGubevl20nE9g=
+github.com/foomo/tlsconfig v0.0.0-20180418120404-b67861b076c9/go.mod h1:OdiGKKgTAfMv7x9Hh9qYFueue77tr09LUAxwy2+M8wY=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20200115085410-6d4e4cb37c7d h1:2+ZP7EfsZV7Vvmx3TIqSlSzATMkTAKqM14YGFPoSKjI=
+golang.org/x/crypto v0.0.0-20200115085410-6d4e4cb37c7d/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3 h1:0GoQqolDA55aaLxZyTzK/Y2ePZzZTUrRacwib7cNsYQ=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.3.0 h1:clyUAQHOM3G0M3f5vQj7LuJrETvjVot3Z5el9nffUtU=
+gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

proxy/handler/staticfiles.go

@@ -4,6 +4,7 @@ import (
 	"mime"
 	"net/http"
 	"os"
+	"path/filepath"
 	"strings"
 	"time"
 
@@ -49,15 +50,7 @@ func fileExists(filename string) bool {
 	return err == nil
 }
 
-func panicOnErr(err error) {
-	if err != nil {
-		panic(err)
-	}
-
-}
-
 func (files *StaticFiles) ServeHTTP(w http.ResponseWriter, incomingRequest *http.Request) {
-
 	parts := strings.Split(incomingRequest.URL.Path, "/")
 	path := strings.Join(parts[4:], "/")
 	moduleNameParts := strings.Split(parts[3], "-")
@@ -68,14 +61,39 @@ func (files *StaticFiles) ServeHTTP(w http.ResponseWriter, incomingRequest *http
 	} else {
 		moduleDir = files.foomo.GetModuleHtdocsVarDir(moduleName)
 	}
-	f, err := os.Open(moduleDir + "/" + path)
-	panicOnErr(err)
+	fullName := filepath.Join(moduleDir, path)
+	// validate path
+	absPath, errAbs := filepath.Abs(fullName)
+	if errAbs != nil {
+		http.Error(w, "forbidden", http.StatusForbidden)
+		return
+	}
+	if !strings.HasPrefix(absPath, moduleDir) {
+		http.Error(w, "forbidden", http.StatusForbidden)
+		return
+	}
+	// check file
+	fileInfo, errStat := os.Stat(fullName)
+	if errStat != nil {
+		switch true {
+		case os.IsNotExist(errStat):
+			http.Error(w, "not found", http.StatusNotFound)
+		case os.IsPermission(errStat):
+			http.Error(w, "forbidden", http.StatusForbidden)
+		default:
+			http.Error(w, "internal server error", http.StatusInternalServerError)
+		}
+		return
+	}
+	// open it
+	f, errOpen := os.Open(fullName)
 	defer f.Close()
+	if errOpen != nil {
+		http.Error(w, "internal server error", http.StatusInternalServerError)
+		return
+	}
+	// compression support
 	_, compress := getContentType(path)
-	//w.Header().Set("Content-Type", mime)
-	fileInfo, err := f.Stat()
-	panicOnErr(err)
-	//const TimeFormat = "Mon, 02 Jan 2006 15:04:05 GMT"
 	w.Header().Set("Expires", time.Now().Add(time.Hour*24*365).Format(http.TimeFormat))
 	if compress && strings.Contains(incomingRequest.Header.Get("Accept-Encoding"), "gzip") {
 		w.Header().Set("Content-Encoding", "gzip")
@@ -83,6 +101,7 @@ func (files *StaticFiles) ServeHTTP(w http.ResponseWriter, incomingRequest *http
 		defer crw.Close()
 		w = crw
 	}
+	// passing it on to std library
 	http.ServeContent(w, incomingRequest, f.Name(), fileInfo.ModTime(), f)
 }
 

proxy/proxy_test.go

@@ -65,6 +65,21 @@ func TestSNI(t *testing.T) {
 	if responseErr != nil {
 		t.Fatal("failed to get", responseErr)
 	}
+
+	response404, response404Err := c.Get("https://localhost:8443/foomo/modulesVar/Foomo.JS/test-is-not-here")
+	if response404Err != nil {
+		t.Fatal("failed to get", response404Err)
+	}
+	if response404.StatusCode != http.StatusNotFound {
+		t.Fatal("unexpected status code:", response404.StatusCode)
+	}
+	responsePathAttack, responsePathAttackErr := c.Get("https://localhost:8443/foomo/modulesVar/Foomo.JS/../../../../etc/passwd")
+	if responsePathAttackErr != nil {
+		t.Fatal("failed to get", responsePathAttackErr)
+	}
+	if responsePathAttack.StatusCode != http.StatusForbidden {
+		t.Fatal("unexpected status code:", response404.StatusCode)
+	}
 	if response.TLS.PeerCertificates[0].Subject.CommonName != "localhost" {
 		t.Fatal("SNI Fail, unexpected common name in first peer certificate common name:", response.TLS.PeerCertificates[0].Subject.CommonName)
 	}