smallwebwaf/internal/waf/waf_test.go

package waf_test

import (
	"net/http"
	"net/http/httptest"
	"net/netip"
	"net/url"
	"reflect"
	"strconv"
	"strings"
	"testing"

	"sneak.berlin/go/smallwebwaf/internal/waf"
)

// defaultDisabledRules are the rules SWWAF_WAF_DISABLED_RULES switches off
// by default.
//
//nolint:gochecknoglobals // a constant cannot be a list
var defaultDisabledRules = []int{920340, 920420, 920440, 920640, 930130, 930140}

// newCoreRuleSet returns the Core Rule Set at paranoia level level, with
// the rules in disabled switched off.
func newCoreRuleSet(t *testing.T, level int, disabled ...int) *waf.CoreRuleSet {
	t.Helper()

	crs, err := waf.New(waf.Params{ParanoiaLevel: level, DisabledRules: disabled})
	if err != nil {
		t.Fatalf("load the Core Rule Set: %v", err)
	}

	return crs
}

// request is a request a test inspects: its method, its target, the path
// and the query as a client sends them, and its headers, each written
// "Name: value".
type request struct {
	method, target string
	headers        []string
}

// get is a GET request for target with headers.
func get(target string, headers ...string) request {
	return request{http.MethodGet, target, headers}
}

// inspect returns what crs finds in r, sent to git.example by a browser,
// whose Host, User-Agent and Accept r.headers may replace.
func inspect(t *testing.T, crs *waf.CoreRuleSet, r request) waf.Result {
	t.Helper()

	result, _ := inspectBody(t, crs, r, "")

	return result
}

// inspectBody is inspect for r with body, which is announced with its
// Content-Length unless it is "", and returns what crs read of body too.
func inspectBody(
	t *testing.T, crs *waf.CoreRuleSet, r request, body string,
) (waf.Result, string) {
	t.Helper()

	req := httptest.NewRequestWithContext(t.Context(), r.method,
		"http://git.example"+r.target, strings.NewReader(body))
	req.Header.Set("User-Agent", "Mozilla/5.0 (X11; Linux x86_64; rv:131.0) "+
		"Gecko/20100101 Firefox/131.0")
	req.Header.Set("Accept", "text/html")

	if body != "" {
		req.Header.Set("Content-Length", strconv.Itoa(len(body)))
	}

	for _, header := range r.headers {
		// Go's server keeps Host and Transfer-Encoding out of the headers.
		name, value, _ := strings.Cut(header, ": ")
		switch name {
		case "Host":
			req.Host = value
		case "Transfer-Encoding":
			req.TransferEncoding = []string{value}
		default:
			req.Header.Set(name, value)
		}
	}

	result, read, err := crs.Inspect(req, netip.MustParseAddr("203.0.113.9"), req.Body)
	if err != nil {
		t.Fatalf("read the body: %v", err)
	}

	return result, string(read)
}

// wantResult checks what crs finds in r.
func wantResult(t *testing.T, crs *waf.CoreRuleSet, r request, want waf.Result) {
	t.Helper()

	if got := inspect(t, crs, r); !reflect.DeepEqual(got, want) {
		t.Errorf("%s %s %q: %+v, want %+v", r.method, r.target, r.headers, got, want)
	}
}

// matched is the result of a request that the rules ids match, each of
// them a critical one, which adds 5 to the score.
func matched(ids ...int) waf.Result {
	const critical = 5

	return waf.Result{RuleIDs: ids, Score: critical * len(ids)}
}

// atDefaults returns the Core Rule Set as smallwebwaf runs it by default.
func atDefaults(t *testing.T) *waf.CoreRuleSet {
	t.Helper()

	return newCoreRuleSet(t, 1, defaultDisabledRules...)
}

// wantChange checks that crs lets through passes, a gitea request one of
// the six changes is for, and still finds result in refused, a request
// like it that the change is not for.
func wantChange(
	t *testing.T, crs *waf.CoreRuleSet, passes, refused request, result waf.Result,
) {
	t.Helper()

	wantResult(t, crs, passes, waf.Result{})
	wantResult(t, crs, refused, result)
}

func TestPutPatchAndDeleteAreAllowed(t *testing.T) {
	t.Parallel()

	crs := atDefaults(t)

	for _, r := range []request{
		{http.MethodPut, "/v2/owner/image/blobs/uploads/1?digest=sha256:ab", nil},
		{http.MethodPatch, "/api/v1/repos/owner/repo/issues/1", nil},
		{http.MethodDelete, "/api/v1/repos/owner/repo/branches/old", nil},
	} {
		wantChange(t, crs, r, request{http.MethodTrace, r.target, nil}, matched(911100))
	}

	wantChange(t, crs, get("/"), request{"PROPFIND", "/", nil}, matched(911100))
}

func TestExpectAndContentEncodingAreAllowed(t *testing.T) {
	t.Parallel()

	const (
		pushType  = "Content-Type: application/x-git-receive-pack-request"
		fetchType = "Content-Type: application/x-git-upload-pack-request"
		length    = "Content-Length: 1024"
		push      = "/owner/repo.git/git-receive-pack"
		fetch     = "/owner/repo.git/git-upload-pack"
	)

	crs := atDefaults(t)

	wantResult(t, crs,
		request{http.MethodPost, push, []string{pushType, length, "Expect: 100-continue"}},
		waf.Result{})
	wantResult(t, crs,
		request{http.MethodPost, fetch, []string{
			fetchType, length, "Content-Encoding: gzip",
		}},
		waf.Result{})

	// Every other header on the Core Rule Set's list stays refused.
	for _, header := range []string{
		"Proxy: http://proxy.example",
		"Lock-Token: token",
		"Content-Range: bytes 0-1023/1024",
		"If: token",
		"X-HTTP-Method-Override: DELETE",
		"X-HTTP-Method: DELETE",
		"X-Method-Override: DELETE",
		"X-Middleware-Subrequest: middleware",
	} {
		wantResult(t, crs,
			request{http.MethodPost, push, []string{pushType, length, header}},
			matched(920450))
	}
}

func TestTransferEncodingIsRead(t *testing.T) {
	t.Parallel()

	// git sends a large push in chunks, with no Content-Length. Without
	// Transfer-Encoding, that would be a POST without a length (920180).
	wantResult(t, atDefaults(t),
		request{http.MethodPost, "/owner/repo.git/git-receive-pack", []string{
			"Content-Type: application/x-git-receive-pack-request",
			"Transfer-Encoding: chunked",
		}},
		waf.Result{})
}

func TestMoreParametersThanCorazaKeepsIsAMatch(t *testing.T) {
	t.Parallel()

	const attack = "id=1'%20OR%20'1'='1"

	crs := atDefaults(t)

	// Coraza keeps 1000: an attack that is the 1000th is read, and one
	// after it is not, but the request is a match all the same.
	wantResult(t, crs, get("/?"+strings.Repeat("a=1&", 999)+attack), matched(942100))
	wantResult(t, crs, get("/?"+strings.Repeat("a=1&", 1000)+attack), matched(900300))

	// So it is with the fields of a form data or JSON body.
	crs = readingBodies(t)

	for _, tc := range []struct{ header, body string }{
		{formData, strings.Repeat("a=1&", 999) + attack},
		{jsonBody, `{"a":[` + strings.Repeat("1,", 998) + `1],"id":"` + injection + `"}`},
	} {
		wantBody(t, crs, post(tc.header), tc.body, matched(942100), tc.body)
	}

	for _, tc := range []struct{ header, body string }{
		{formData, strings.Repeat("a=1&", 1000) + attack},
		{jsonBody, `{"a":[` + strings.Repeat("1,", 999) + `1],"id":"` + injection + `"}`},
	} {
		wantBody(t, crs, post(tc.header), tc.body, matched(900300), tc.body)
	}
}

func TestRedirectURIMayNameALocalAddress(t *testing.T) {
	t.Parallel()

	const oauth = "/login/oauth/authorize?client_id=tea&response_type=code&"

	crs := atDefaults(t)

	wantChange(t, crs, get(oauth+"redirect_uri=http://127.0.0.1:52341/"),
		get(oauth+"next=http://127.0.0.1:52341/"), matched(931100, 934110))
	wantChange(t, crs, get(oauth+"redirect_uri=http://localhost:52341/"),
		get(oauth+"next=http://localhost:52341/"), matched(934110))
}

func TestParametersGiteaSendsNamesInSkipTheListsOfFilesPathsAndCommands(t *testing.T) {
	t.Parallel()

	crs := atDefaults(t)

	for _, value := range []struct {
		name string
		// result is what a parameter that is not one of gitea's gets.
		result waf.Result
	}{
		// A file on the list of system files.
		{".gitignore", matched(930120)},
		// A command's name, after a directory on the list of shell paths.
		{"bin/docker-entrypoint", matched(932260, 932160)},
	} {
		for _, parameter := range []string{
			"path", "files", "skip-to", "sub_path", "ref", "sha", "branch", "workflow",
			"artifactName", "redirect_to",
		} {
			wantChange(t, crs, get("/?"+parameter+"="+value.name),
				get("/?q="+value.name), value.result)
		}
	}

	// What only those rules refuse gets through there too, but path
	// traversal and SQL injection are still refused.
	wantChange(t, crs, get("/?path=|cat%20/etc/passwd"), get("/?q=|cat%20/etc/passwd"),
		matched(930120, 932160))
	wantResult(t, crs, get("/?path=../../etc/passwd"),
		waf.Result{RuleIDs: []int{930100, 930110}, Score: 20})
	wantResult(t, crs, get("/?path=1'%20OR%20'1'='1"), matched(942100))
}

func TestParameterNamesAreMatchedWithoutRegardToCase(t *testing.T) {
	t.Parallel()

	crs := atDefaults(t)

	wantChange(t, crs, get("/?Path=.gitignore"), get("/?q=.gitignore"), matched(930120))
	wantChange(t, crs, get("/?REDIRECT_URI=http://127.0.0.1:52341/"),
		get("/?next=http://127.0.0.1:52341/"), matched(931100, 934110))
}

func TestCookiesGiteaFlashAndRedirectToAreNotRead(t *testing.T) {
	t.Parallel()

	const (
		flash      = "success%3DFile%2Bpackage.json%2Bdeleted"
		redirectTo = "%2Fowner%2Frepo%2Fsrc%2Fbranch%2Fmain%2Fpackage.json"
	)

	crs := atDefaults(t)

	wantChange(t, crs, get("/owner/repo", "Cookie: gitea_flash="+flash),
		get("/owner/repo", "Cookie: flash="+flash), matched(930120))
	wantChange(t, crs, get("/", "Cookie: redirect_to="+redirectTo),
		get("/", "Cookie: redirect="+redirectTo), matched(930120))

	// Among other cookies, which are read.
	wantChange(t, crs,
		get("/", "Cookie: lang=en-US; gitea_flash="+flash+"; redirect_to="+redirectTo+
			"; i_like_gitea=abc"),
		get("/", "Cookie: lang=en-US; gitea_flash="+flash+"; redirect="+redirectTo+
			"; i_like_gitea=abc"),
		matched(930120))
}

func TestRefererIsNotCheckedForACommandOrJavaStartingAProcess(t *testing.T) {
	t.Parallel()

	const (
		search      = "https://git.example/explore/repos?q=env"
		runtimeJava = "https://git.example/openjdk/jdk/src/branch/master/src/" +
			"java.base/share/classes/java/lang/Runtime.java"
	)

	crs := atDefaults(t)

	wantChange(t, crs, get("/", "Referer: "+search), get("/", "User-Agent: "+search),
		matched(932340))
	wantChange(t, crs, get("/", "Referer: "+runtimeJava),
		get("/", "X-Page: "+runtimeJava), matched(944110))

	// It is still checked for script and SQL injection.
	wantResult(t, crs,
		get("/", "Referer: https://git.example/?q=<script>alert(1)</script>"),
		matched(941110, 941160))
	wantResult(t, crs, get("/", "Referer: https://git.example/?q=1' OR '1'='1"),
		matched(942100))
}

func TestEmptyHeaderIsRead(t *testing.T) {
	t.Parallel()

	// An empty User-Agent is a notice, which adds 2.
	wantResult(t, atDefaults(t), get("/", "User-Agent: "),
		waf.Result{RuleIDs: []int{920330}, Score: 2})
}

func TestParanoiaLevel(t *testing.T) {
	t.Parallel()

	// Accept-Charset is refused from paranoia level 2.
	r := get("/", "Accept-Charset: utf-8")

	wantResult(t, newCoreRuleSet(t, 1), r, waf.Result{})
	wantResult(t, newCoreRuleSet(t, 2), r, matched(920451))
}

func TestEachDisabledRuleIsSwitchedOff(t *testing.T) {
	t.Parallel()

	// A method not allowed, and a Host that is an IP address, a warning,
	// which adds 3.
	r := request{http.MethodTrace, "/", []string{"Host: 192.0.2.1"}}

	wantResult(t, newCoreRuleSet(t, 1), r,
		waf.Result{RuleIDs: []int{911100, 920350}, Score: 8})
	wantResult(t, newCoreRuleSet(t, 1, 920350, 911100), r, waf.Result{})
}

// bodyLimit is SWWAF_WAF_BODY_LIMIT in the tests that read bodies.
const bodyLimit = 8 << 10

// The Content-Type headers of the kinds of body the Core Rule Set reads.
const (
	formData  = "Content-Type: application/x-www-form-urlencoded"
	multipart = "Content-Type: multipart/form-data; boundary=b"
	jsonBody  = "Content-Type: application/json"
	xmlBody   = "Content-Type: application/xml"
)

// injection is an SQL injection, which rule 942100 matches.
const injection = "1' OR '1'='1"

// readingBodies returns the Core Rule Set as smallwebwaf runs it by
// default, but reading bodies up to bodyLimit.
func readingBodies(t *testing.T) *waf.CoreRuleSet {
	t.Helper()

	crs, err := waf.New(waf.Params{
		ParanoiaLevel: 1, DisabledRules: defaultDisabledRules, BodyLimit: bodyLimit,
	})
	if err != nil {
		t.Fatalf("load the Core Rule Set: %v", err)
	}

	return crs
}

// post is a POST request for / with a body of the type contentType, a
// Content-Type header, gives, and headers besides.
func post(contentType string, headers ...string) request {
	return request{http.MethodPost, "/", append([]string{contentType}, headers...)}
}

// field is a part of a multipart body: the field name, holding value.
func field(name, value string) string {
	return "--b\r\nContent-Disposition: form-data; name=\"" + name + "\"\r\n\r\n" +
		value + "\r\n"
}

// end ends a multipart body.
const end = "--b--\r\n"

// padded returns head and tail with as many a's between them as make n
// bytes in all.
func padded(head, tail string, n int) string {
	return head + strings.Repeat("a", n-len(head)-len(tail)) + tail
}

// wantBody checks what crs finds in r with body, and that what it read of
// body is read.
func wantBody(
	t *testing.T, crs *waf.CoreRuleSet, r request, body string, want waf.Result,
	read string,
) {
	t.Helper()

	got, gotRead := inspectBody(t, crs, r, body)
	if !reflect.DeepEqual(got, want) || gotRead != read {
		t.Errorf("%q with a body of %d bytes, %.40q: %+v, reading %d bytes, "+
			"want %+v, reading %d", r.headers, len(body), body, got, len(gotRead),
			want, len(read))
	}
}

func TestBodiesAreReadOnlyWhileBodyLimitIsSet(t *testing.T) {
	t.Parallel()

	off, on := atDefaults(t), readingBodies(t)

	for _, tc := range []struct{ header, body string }{
		{formData, "q=" + url.QueryEscape(injection)},
		{multipart, field("q", injection) + end},
		{jsonBody, `{"q":"` + injection + `"}`},
		{xmlBody, "<q>" + injection + "</q>"},
	} {
		wantBody(t, off, post(tc.header), tc.body, waf.Result{}, "")
		wantBody(t, on, post(tc.header), tc.body, matched(942100), tc.body)
	}
}

func TestFormDataAndMultipartAreReadUpToTheLimit(t *testing.T) {
	t.Parallel()

	crs := readingBodies(t)
	pad := strings.Repeat("a", bodyLimit)

	for _, tc := range []struct{ header, attackFirst, attackLast string }{
		{
			formData, "q=" + url.QueryEscape(injection) + "&pad=" + pad,
			"pad=" + pad + "&q=" + url.QueryEscape(injection),
		},
		{
			multipart, field("q", injection) + field("pad", pad) + end,
			field("pad", pad) + field("q", injection) + end,
		},
	} {
		wantBody(t, crs, post(tc.header), tc.attackFirst, matched(942100),
			tc.attackFirst[:bodyLimit+1])
		wantBody(t, crs, post(tc.header), tc.attackLast, waf.Result{},
			tc.attackLast[:bodyLimit+1])
	}
}

func TestJSONAndXMLAreReadOnlyWhenNoLargerThanTheLimit(t *testing.T) {
	t.Parallel()

	crs := readingBodies(t)

	for _, tc := range []struct{ header, head, tail string }{
		{jsonBody, `{"q":"` + injection + `","pad":"`, `"}`},
		{xmlBody, "<r><q>" + injection + "</q><pad>", "</pad></r>"},
	} {
		fits := padded(tc.head, tc.tail, bodyLimit)
		wantBody(t, crs, post(tc.header), fits, matched(942100), fits)

		larger := padded(tc.head, tc.tail, bodyLimit+1)
		wantBody(t, crs, post(tc.header), larger, waf.Result{}, larger)
	}
}

func TestOtherBodiesAreNotRead(t *testing.T) {
	t.Parallel()

	crs := readingBodies(t)

	// Read as form data, which the Core Rule Set does with a body of a type
	// it does not know, this would be an SQL injection.
	body := "q=" + url.QueryEscape(injection)

	for _, header := range []string{
		"Content-Type: application/octet-stream",
		"Content-Type: text/plain",
		"Content-Type: application/x-git-receive-pack-request",
	} {
		wantBody(t, crs, post(header), body, waf.Result{}, "")
	}
}

func TestContentEncodingIsRefusedOnTheKindsOfBodyTheCoreRuleSetReads(t *testing.T) {
	t.Parallel()

	const gzip = "Content-Encoding: gzip"

	crs := readingBodies(t)

	for _, header := range []string{formData, multipart, jsonBody, xmlBody} {
		wantBody(t, crs, post(header, gzip), "a", matched(920450), "a")
	}

	// Whatever its size: a JSON body larger than the limit is not read, but
	// Content-Encoding on it is refused all the same.
	larger := strings.Repeat("a", bodyLimit+1)
	wantBody(t, crs, post(jsonBody, gzip), larger, matched(920450), larger)

	// It is allowed on a body of any other kind, and on every body while no
	// body is read.
	fetch := "Content-Type: application/x-git-upload-pack-request"
	wantBody(t, crs, post(fetch, gzip), "a", waf.Result{}, "")
	wantBody(t, atDefaults(t), post(formData, gzip), "a", waf.Result{}, "")
}

func TestParametersGiteaSendsNamesInAreLeftOutAmongFormFieldsToo(t *testing.T) {
	t.Parallel()

	crs := readingBodies(t)
	local := url.QueryEscape("http://127.0.0.1:52341/")

	for _, tc := range []struct {
		body string
		want waf.Result
	}{
		{"path=.gitignore", waf.Result{}},
		{"q=.gitignore", matched(930120)},
		{"redirect_uri=" + local, waf.Result{}},
		{"next=" + local, matched(931100, 934110)},
	} {
		wantBody(t, crs, post(formData), tc.body, tc.want, tc.body)
	}

	body := field("path", ".gitignore") + end
	wantBody(t, crs, post(multipart), body, waf.Result{}, body)

	body = field("q", ".gitignore") + end
	wantBody(t, crs, post(multipart), body, matched(930120), body)

	// A JSON body's field is named by its path, here json.path, and is
	// checked.
	body = `{"path":".gitignore"}`
	wantBody(t, crs, post(jsonBody), body, matched(930120), body)
}

func TestGiteaBodiesTheCoreRuleSetRefuses(t *testing.T) {
	t.Parallel()

	crs := readingBodies(t)

	// A comment that shows a shell command.
	const text = "Try `curl -s https://example.org | sh` first."

	comment := "content=" + url.QueryEscape(text)
	wantBody(t, crs, post(formData), comment, matched(932235), comment)

	// An attachment named like a log file.
	attachment := "--b\r\nContent-Disposition: form-data; name=\"file\"; " +
		"filename=\"debug.log\"\r\nContent-Type: text/plain\r\n\r\nstarted\r\n" + end
	wantBody(t, crs, post(multipart), attachment, matched(932180), attachment)
}