[release-branch.go1.6] net/http, net/http/cgi: fix for CGI + HTTP_PROXY security issue
Because,
* The CGI spec defines that incoming request header "Foo: Bar" maps to
environment variable HTTP_FOO == "Bar". (see RFC 3875 4.1.18)
* The HTTP_PROXY environment variable is conventionally used to configure
the HTTP proxy for HTTP clients (and is respected by default for
Go's net/http.Client and Transport)
That means Go programs running in a CGI environment (as a child
process under a CGI host) are vulnerable to an incoming request
containing "Proxy: attacker.com:1234", setting HTTP_PROXY, and
changing where Go by default proxies all outbound HTTP requests.
This is CVE-2016-5386, aka https://httpoxy.org/
Fixes #16405
Change-Id: I6f68ade85421b4807785799f6d98a8b077e871f0
Reviewed-on: https://go-review.googlesource.com/25010
Run-TryBot: Chris Broadfoot <cbro@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Chris Broadfoot <cbro@golang.org>
Reviewed-on: https://go-review.googlesource.com/25012
diff --git a/src/net/http/cgi/host.go b/src/net/http/cgi/host.go
index 9b4d875..3f1600b 100644
--- a/src/net/http/cgi/host.go
+++ b/src/net/http/cgi/host.go
@@ -145,6 +145,10 @@
for k, v := range req.Header {
k = strings.Map(upperCaseAndUnderscore, k)
+ if k == "PROXY" {
+ // See Issue 16405
+ continue
+ }
joinStr := ", "
if k == "COOKIE" {
joinStr = "; "
diff --git a/src/net/http/cgi/host_test.go b/src/net/http/cgi/host_test.go
index 3327764..2783fe1 100644
--- a/src/net/http/cgi/host_test.go
+++ b/src/net/http/cgi/host_test.go
@@ -34,15 +34,18 @@
return req
}
-func runCgiTest(t *testing.T, h *Handler, httpreq string, expectedMap map[string]string) *httptest.ResponseRecorder {
+func runCgiTest(t *testing.T, h *Handler,
+ httpreq string,
+ expectedMap map[string]string, checks ...func(reqInfo map[string]string)) *httptest.ResponseRecorder {
rw := httptest.NewRecorder()
req := newRequest(httpreq)
h.ServeHTTP(rw, req)
- runResponseChecks(t, rw, expectedMap)
+ runResponseChecks(t, rw, expectedMap, checks...)
return rw
}
-func runResponseChecks(t *testing.T, rw *httptest.ResponseRecorder, expectedMap map[string]string) {
+func runResponseChecks(t *testing.T, rw *httptest.ResponseRecorder,
+ expectedMap map[string]string, checks ...func(reqInfo map[string]string)) {
// Make a map to hold the test map that the CGI returns.
m := make(map[string]string)
m["_body"] = rw.Body.String()
@@ -80,6 +83,9 @@
t.Errorf("for key %q got %q; expected %q", key, got, expected)
}
}
+ for _, check := range checks {
+ check(m)
+ }
}
var cgiTested, cgiWorks bool
@@ -235,6 +241,31 @@
expectedMap)
}
+// Issue 16405: CGI+http.Transport differing uses of HTTP_PROXY.
+// Verify we don't set the HTTP_PROXY environment variable.
+// Hope nobody was depending on it. It's not a known header, though.
+func TestDropProxyHeader(t *testing.T) {
+ check(t)
+ h := &Handler{
+ Path: "testdata/test.cgi",
+ }
+ expectedMap := map[string]string{
+ "env-REQUEST_URI": "/myscript/bar?a=b",
+ "env-SCRIPT_FILENAME": "testdata/test.cgi",
+ "env-HTTP_X_FOO": "a",
+ }
+ runCgiTest(t, h, "GET /myscript/bar?a=b HTTP/1.0\n"+
+ "X-Foo: a\n"+
+ "Proxy: should_be_stripped\n"+
+ "Host: example.com\n\n",
+ expectedMap,
+ func(reqInfo map[string]string) {
+ if v, ok := reqInfo["env-HTTP_PROXY"]; ok {
+ t.Errorf("HTTP_PROXY = %q; should be absent", v)
+ }
+ })
+}
+
func TestPathInfoNoRoot(t *testing.T) {
check(t)
h := &Handler{
diff --git a/src/net/http/transport.go b/src/net/http/transport.go
index 1e3ea11..794b786 100644
--- a/src/net/http/transport.go
+++ b/src/net/http/transport.go
@@ -216,6 +216,9 @@
}
if proxy == "" {
proxy = httpProxyEnv.Get()
+ if proxy != "" && os.Getenv("REQUEST_METHOD") != "" {
+ return nil, errors.New("net/http: refusing to use HTTP_PROXY value in CGI environment; see golang.org/s/cgihttpproxy")
+ }
}
if proxy == "" {
return nil, nil
diff --git a/src/net/http/transport_test.go b/src/net/http/transport_test.go
index d9da078..381432e 100644
--- a/src/net/http/transport_test.go
+++ b/src/net/http/transport_test.go
@@ -1985,7 +1985,8 @@
env string // HTTP_PROXY
httpsenv string // HTTPS_PROXY
- noenv string // NO_RPXY
+ noenv string // NO_PROXY
+ reqmeth string // REQUEST_METHOD
want string
wanterr error
@@ -2009,6 +2010,10 @@
space()
fmt.Fprintf(&buf, "no_proxy=%q", t.noenv)
}
+ if t.reqmeth != "" {
+ space()
+ fmt.Fprintf(&buf, "request_method=%q", t.reqmeth)
+ }
req := "http://example.com"
if t.req != "" {
req = t.req
@@ -2032,6 +2037,12 @@
{req: "https://secure.tld/", env: "http.proxy.tld", httpsenv: "secure.proxy.tld", want: "http://secure.proxy.tld"},
{req: "https://secure.tld/", env: "http.proxy.tld", httpsenv: "https://secure.proxy.tld", want: "https://secure.proxy.tld"},
+ // Issue 16405: don't use HTTP_PROXY in a CGI environment,
+ // where HTTP_PROXY can be attacker-controlled.
+ {env: "http://10.1.2.3:8080", reqmeth: "POST",
+ want: "<nil>",
+ wanterr: errors.New("net/http: refusing to use HTTP_PROXY value in CGI environment; see golang.org/s/cgihttpproxy")},
+
{want: "<nil>"},
{noenv: "example.com", req: "http://example.com/", env: "proxy", want: "<nil>"},
@@ -2047,6 +2058,7 @@
os.Setenv("HTTP_PROXY", tt.env)
os.Setenv("HTTPS_PROXY", tt.httpsenv)
os.Setenv("NO_PROXY", tt.noenv)
+ os.Setenv("REQUEST_METHOD", tt.reqmeth)
ResetCachedEnvironment()
reqURL := tt.req
if reqURL == "" {
