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Refactor CSRF protector (#32057) (#32069) 

#32057 improves the CSRF handling and is worth to backport
This commit is contained in:
wxiaoguang 2024-09-19 01:02:45 +08:00 committed by GitHub
parent 8dbe83d205
commit 2891edbbcb
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GPG Key ID: B5690EEEBB952194
7 changed files with 71 additions and 172 deletions
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2
options/locale/locale_en-US.ini
View File

@ -218,8 +218,6 @@ string.desc = Z - A
[error]
occurred = An error occurred
report_message = If you believe that this is a Gitea bug, please search for issues on <a href="https://github.com/go-gitea/gitea/issues" target="_blank">GitHub</a> or open a new issue if necessary.
missing_csrf = Bad Request: no CSRF token present
invalid_csrf = Bad Request: invalid CSRF token
not_found = The target couldn't be found.
network_error = Network error

2
routers/web/web.go
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@ -129,6 +129,8 @@ func webAuth(authMethod auth_service.Method) func(*context.Context) {
// ensure the session uid is deleted
_ = ctx.Session.Delete("uid")
}
ctx.Csrf.PrepareForSessionUser(ctx)
}
}

6
services/context/context.go
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@ -138,10 +138,8 @@ func Contexter() func(next http.Handler) http.Handler {
csrfOpts := CsrfOptions{
Secret: hex.EncodeToString(setting.GetGeneralTokenSigningSecret()),
Cookie: setting.CSRFCookieName,
SetCookie: true,
Secure: setting.SessionConfig.Secure,
CookieHTTPOnly: setting.CSRFCookieHTTPOnly,
Header: "X-Csrf-Token",
CookieDomain: setting.SessionConfig.Domain,
CookiePath: setting.SessionConfig.CookiePath,
SameSite: setting.SessionConfig.SameSite,
@ -167,7 +165,7 @@ func Contexter() func(next http.Handler) http.Handler {
ctx.Base.AppendContextValue(WebContextKey, ctx)
ctx.Base.AppendContextValueFunc(gitrepo.RepositoryContextKey, func() any { return ctx.Repo.GitRepo })
ctx.Csrf = PrepareCSRFProtector(csrfOpts, ctx)
ctx.Csrf = NewCSRFProtector(csrfOpts)
// Get the last flash message from cookie
lastFlashCookie := middleware.GetSiteCookie(ctx.Req, CookieNameFlash)
@ -204,8 +202,6 @@ func Contexter() func(next http.Handler) http.Handler {
ctx.Resp.Header().Set(`X-Frame-Options`, setting.CORSConfig.XFrameOptions)
ctx.Data["SystemConfig"] = setting.Config()
ctx.Data["CsrfToken"] = ctx.Csrf.GetToken()
ctx.Data["CsrfTokenHtml"] = template.HTML(`<input type="hidden" name="_csrf" value="` + ctx.Data["CsrfToken"].(string) + `">`)
// FIXME: do we really always need these setting? There should be someway to have to avoid having to always set these
ctx.Data["DisableMigrations"] = setting.Repository.DisableMigrations

182
services/context/csrf.go
View File

@ -20,64 +20,42 @@
package context
import (
"encoding/base32"
"fmt"
"html/template"
"net/http"
"strconv"
"time"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/setting"
"code.gitea.io/gitea/modules/util"
"code.gitea.io/gitea/modules/web/middleware"
)
const (
CsrfHeaderName = "X-Csrf-Token"
CsrfFormName = "_csrf"
)
// CSRFProtector represents a CSRF protector and is used to get the current token and validate the token.
type CSRFProtector interface {
// GetHeaderName returns HTTP header to search for token.
GetHeaderName() string
// GetFormName returns form value to search for token.
GetFormName() string
// GetToken returns the token.
GetToken() string
// Validate validates the token in http context.
// PrepareForSessionUser prepares the csrf protector for the current session user.
PrepareForSessionUser(ctx *Context)
// Validate validates the csrf token in http context.
Validate(ctx *Context)
// DeleteCookie deletes the cookie
// DeleteCookie deletes the csrf cookie
DeleteCookie(ctx *Context)
}
type csrfProtector struct {
opt CsrfOptions
// Token generated to pass via header, cookie, or hidden form value.
Token string
// This value must be unique per user.
ID string
}
// GetHeaderName returns the name of the HTTP header for csrf token.
func (c *csrfProtector) GetHeaderName() string {
return c.opt.Header
}
// GetFormName returns the name of the form value for csrf token.
func (c *csrfProtector) GetFormName() string {
return c.opt.Form
}
// GetToken returns the current token. This is typically used
// to populate a hidden form in an HTML template.
func (c *csrfProtector) GetToken() string {
return c.Token
// id must be unique per user.
id string
// token is the valid one which wil be used by end user and passed via header, cookie, or hidden form value.
token string
}
// CsrfOptions maintains options to manage behavior of Generate.
type CsrfOptions struct {
// The global secret value used to generate Tokens.
Secret string
// HTTP header used to set and get token.
Header string
// Form value used to set and get token.
Form string
// Cookie value used to set and get token.
Cookie string
// Cookie domain.
@ -87,103 +65,64 @@ type CsrfOptions struct {
CookieHTTPOnly bool
// SameSite set the cookie SameSite type
SameSite http.SameSite
// Key used for getting the unique ID per user.
SessionKey string
// oldSessionKey saves old value corresponding to SessionKey.
oldSessionKey string
// If true, send token via X-Csrf-Token header.
SetHeader bool
// If true, send token via _csrf cookie.
SetCookie bool
// Set the Secure flag to true on the cookie.
Secure bool
// Disallow Origin appear in request header.
Origin bool
// Cookie lifetime. Default is 0
CookieLifeTime int
// sessionKey is the key used for getting the unique ID per user.
sessionKey string
// oldSessionKey saves old value corresponding to sessionKey.
oldSessionKey string
}
func prepareDefaultCsrfOptions(opt CsrfOptions) CsrfOptions {
if opt.Secret == "" {
randBytes, err := util.CryptoRandomBytes(8)
if err != nil {
// this panic can be handled by the recover() in http handlers
panic(fmt.Errorf("failed to generate random bytes: %w", err))
}
opt.Secret = base32.StdEncoding.EncodeToString(randBytes)
}
if opt.Header == "" {
opt.Header = "X-Csrf-Token"
}
if opt.Form == "" {
opt.Form = "_csrf"
}
if opt.Cookie == "" {
opt.Cookie = "_csrf"
}
if opt.CookiePath == "" {
opt.CookiePath = "/"
}
if opt.SessionKey == "" {
opt.SessionKey = "uid"
}
if opt.CookieLifeTime == 0 {
opt.CookieLifeTime = int(CsrfTokenTimeout.Seconds())
}
opt.oldSessionKey = "_old_" + opt.SessionKey
return opt
}
func newCsrfCookie(c *csrfProtector, value string) *http.Cookie {
func newCsrfCookie(opt *CsrfOptions, value string) *http.Cookie {
return &http.Cookie{
Name: c.opt.Cookie,
Name: opt.Cookie,
Value: value,
Path: c.opt.CookiePath,
Domain: c.opt.CookieDomain,
MaxAge: c.opt.CookieLifeTime,
Secure: c.opt.Secure,
HttpOnly: c.opt.CookieHTTPOnly,
SameSite: c.opt.SameSite,
Path: opt.CookiePath,
Domain: opt.CookieDomain,
MaxAge: int(CsrfTokenTimeout.Seconds()),
Secure: opt.Secure,
HttpOnly: opt.CookieHTTPOnly,
SameSite: opt.SameSite,
}
}
// PrepareCSRFProtector returns a CSRFProtector to be used for every request.
// Additionally, depending on options set, generated tokens will be sent via Header and/or Cookie.
func PrepareCSRFProtector(opt CsrfOptions, ctx *Context) CSRFProtector {
opt = prepareDefaultCsrfOptions(opt)
x := &csrfProtector{opt: opt}
if opt.Origin && len(ctx.Req.Header.Get("Origin")) > 0 {
return x
func NewCSRFProtector(opt CsrfOptions) CSRFProtector {
if opt.Secret == "" {
panic("CSRF secret is empty but it must be set") // it shouldn't happen because it is always set in code
}
opt.Cookie = util.IfZero(opt.Cookie, "_csrf")
opt.CookiePath = util.IfZero(opt.CookiePath, "/")
opt.sessionKey = "uid"
opt.oldSessionKey = "_old_" + opt.sessionKey
return &csrfProtector{opt: opt}
}
x.ID = "0"
uidAny := ctx.Session.Get(opt.SessionKey)
if uidAny != nil {
func (c *csrfProtector) PrepareForSessionUser(ctx *Context) {
c.id = "0"
if uidAny := ctx.Session.Get(c.opt.sessionKey); uidAny != nil {
switch uidVal := uidAny.(type) {
case string:
x.ID = uidVal
c.id = uidVal
case int64:
x.ID = strconv.FormatInt(uidVal, 10)
c.id = strconv.FormatInt(uidVal, 10)
default:
log.Error("invalid uid type in session: %T", uidAny)
}
}
oldUID := ctx.Session.Get(opt.oldSessionKey)
uidChanged := oldUID == nil || oldUID.(string) != x.ID
cookieToken := ctx.GetSiteCookie(opt.Cookie)
oldUID := ctx.Session.Get(c.opt.oldSessionKey)
uidChanged := oldUID == nil || oldUID.(string) != c.id
cookieToken := ctx.GetSiteCookie(c.opt.Cookie)
needsNew := true
if uidChanged {
_ = ctx.Session.Set(opt.oldSessionKey, x.ID)
_ = ctx.Session.Set(c.opt.oldSessionKey, c.id)
} else if cookieToken != "" {
// If cookie token presents, re-use existing unexpired token, else generate a new one.
if issueTime, ok := ParseCsrfToken(cookieToken); ok {
dur := time.Since(issueTime) // issueTime is not a monotonic-clock, the server time may change a lot to an early time.
if dur >= -CsrfTokenRegenerationInterval && dur <= CsrfTokenRegenerationInterval {
x.Token = cookieToken
c.token = cookieToken
needsNew = false
}
}
@ -191,42 +130,33 @@ func PrepareCSRFProtector(opt CsrfOptions, ctx *Context) CSRFProtector {
if needsNew {
// FIXME: actionId.
x.Token = GenerateCsrfToken(x.opt.Secret, x.ID, "POST", time.Now())
if opt.SetCookie {
cookie := newCsrfCookie(x, x.Token)
c.token = GenerateCsrfToken(c.opt.Secret, c.id, "POST", time.Now())
cookie := newCsrfCookie(&c.opt, c.token)
ctx.Resp.Header().Add("Set-Cookie", cookie.String())
}
}
if opt.SetHeader {
ctx.Resp.Header().Add(opt.Header, x.Token)
}
return x
ctx.Data["CsrfToken"] = c.token
ctx.Data["CsrfTokenHtml"] = template.HTML(`<input type="hidden" name="_csrf" value="` + template.HTMLEscapeString(c.token) + `">`)
}
func (c *csrfProtector) validateToken(ctx *Context, token string) {
if !ValidCsrfToken(token, c.opt.Secret, c.ID, "POST", time.Now()) {
if !ValidCsrfToken(token, c.opt.Secret, c.id, "POST", time.Now()) {
c.DeleteCookie(ctx)
if middleware.IsAPIPath(ctx.Req) {
// currently, there should be no access to the APIPath with CSRF token. because templates shouldn't use the `/api/` endpoints.
// FIXME: distinguish what the response is for: HTML (web page) or JSON (fetch)
http.Error(ctx.Resp, "Invalid CSRF token.", http.StatusBadRequest)
} else {
ctx.Flash.Error(ctx.Tr("error.invalid_csrf"))
ctx.Redirect(setting.AppSubURL + "/")
}
}
}
// Validate should be used as a per route middleware. It attempts to get a token from an "X-Csrf-Token"
// HTTP header and then a "_csrf" form value. If one of these is found, the token will be validated.
// If this validation fails, custom Error is sent in the reply.
// If neither a header nor form value is found, http.StatusBadRequest is sent.
// If this validation fails, http.StatusBadRequest is sent.
func (c *csrfProtector) Validate(ctx *Context) {
if token := ctx.Req.Header.Get(c.GetHeaderName()); token != "" {
if token := ctx.Req.Header.Get(CsrfHeaderName); token != "" {
c.validateToken(ctx, token)
return
}
if token := ctx.Req.FormValue(c.GetFormName()); token != "" {
if token := ctx.Req.FormValue(CsrfFormName); token != "" {
c.validateToken(ctx, token)
return
}
@ -234,9 +164,7 @@ func (c *csrfProtector) Validate(ctx *Context) {
}
func (c *csrfProtector) DeleteCookie(ctx *Context) {
if c.opt.SetCookie {
cookie := newCsrfCookie(c, "")
cookie := newCsrfCookie(&c.opt, "")
cookie.MaxAge = -1
ctx.Resp.Header().Add("Set-Cookie", cookie.String())
}
}

3
tests/integration/attachment_test.go
View File

@ -59,7 +59,8 @@ func createAttachment(t *testing.T, session *TestSession, repoURL, filename stri
func TestCreateAnonymousAttachment(t *testing.T) {
defer tests.PrepareTestEnv(t)()
session := emptyTestSession(t)
createAttachment(t, session, "user2/repo1", "image.png", generateImg(), http.StatusSeeOther)
// this test is not right because it just doesn't pass the CSRF validation
createAttachment(t, session, "user2/repo1", "image.png", generateImg(), http.StatusBadRequest)
}
func TestCreateIssueAttachment(t *testing.T) {

26
tests/integration/csrf_test.go
View File

@ -5,12 +5,10 @@ package integration
import (
"net/http"
"strings"
"testing"
"code.gitea.io/gitea/models/unittest"
user_model "code.gitea.io/gitea/models/user"
"code.gitea.io/gitea/modules/setting"
"code.gitea.io/gitea/tests"
"github.com/stretchr/testify/assert"
@ -25,28 +23,12 @@ func TestCsrfProtection(t *testing.T) {
req := NewRequestWithValues(t, "POST", "/user/settings", map[string]string{
"_csrf": "fake_csrf",
})
session.MakeRequest(t, req, http.StatusSeeOther)
resp := session.MakeRequest(t, req, http.StatusSeeOther)
loc := resp.Header().Get("Location")
assert.Equal(t, setting.AppSubURL+"/", loc)
resp = session.MakeRequest(t, NewRequest(t, "GET", loc), http.StatusOK)
htmlDoc := NewHTMLParser(t, resp.Body)
assert.Equal(t, "Bad Request: invalid CSRF token",
strings.TrimSpace(htmlDoc.doc.Find(".ui.message").Text()),
)
resp := session.MakeRequest(t, req, http.StatusBadRequest)
assert.Contains(t, resp.Body.String(), "Invalid CSRF token")
// test web form csrf via header. TODO: should use an UI api to test
req = NewRequest(t, "POST", "/user/settings")
req.Header.Add("X-Csrf-Token", "fake_csrf")
session.MakeRequest(t, req, http.StatusSeeOther)
resp = session.MakeRequest(t, req, http.StatusSeeOther)
loc = resp.Header().Get("Location")
assert.Equal(t, setting.AppSubURL+"/", loc)
resp = session.MakeRequest(t, NewRequest(t, "GET", loc), http.StatusOK)
htmlDoc = NewHTMLParser(t, resp.Body)
assert.Equal(t, "Bad Request: invalid CSRF token",
strings.TrimSpace(htmlDoc.doc.Find(".ui.message").Text()),
)
resp = session.MakeRequest(t, req, http.StatusBadRequest)
assert.Contains(t, resp.Body.String(), "Invalid CSRF token")
}

12
tests/integration/repo_branch_test.go
View File

@ -17,7 +17,6 @@ import (
repo_model "code.gitea.io/gitea/models/repo"
"code.gitea.io/gitea/models/unit"
"code.gitea.io/gitea/models/unittest"
"code.gitea.io/gitea/modules/setting"
api "code.gitea.io/gitea/modules/structs"
"code.gitea.io/gitea/modules/test"
"code.gitea.io/gitea/modules/translation"
@ -146,15 +145,8 @@ func TestCreateBranchInvalidCSRF(t *testing.T) {
"_csrf": "fake_csrf",
"new_branch_name": "test",
})
resp := session.MakeRequest(t, req, http.StatusSeeOther)
loc := resp.Header().Get("Location")
assert.Equal(t, setting.AppSubURL+"/", loc)
resp = session.MakeRequest(t, NewRequest(t, "GET", loc), http.StatusOK)
htmlDoc := NewHTMLParser(t, resp.Body)
assert.Equal(t,
"Bad Request: invalid CSRF token",
strings.TrimSpace(htmlDoc.doc.Find(".ui.message").Text()),
)
resp := session.MakeRequest(t, req, http.StatusBadRequest)
assert.Contains(t, resp.Body.String(), "Invalid CSRF token")
}
func prepareBranch(t *testing.T, session *TestSession, repo *repo_model.Repository) {