Remove form-action CSP directive

Chrome incorrectly restricts the redirect URL to the sources specified
in the form-action value, which prevents the instance oauth page from
loading.

bloat.conf

@@ -38,5 +38,4 @@ post_formats=PlainText:text/plain,HTML:text/html,Markdown:text/markdown,BBCode:t
 # single_instance=pl.mydomain.com
 
 # Path to custom CSS. Value can be a file path relative to the static directory.
-# or a URL starting with either "http://" or "https://".
 # custom_css=custom.css

main.go

@@ -8,7 +8,6 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
-	"strings"
 
 	"bloat/config"
 	"bloat/renderer"
@@ -47,14 +46,8 @@ func main() {
 		errExit(err)
 	}
 
-	customCSS := config.CustomCSS
-	if len(customCSS) > 0 && !strings.HasPrefix(customCSS, "http://") &&
-		!strings.HasPrefix(customCSS, "https://") {
-		customCSS = "/static/" + customCSS
-	}
-
 	s := service.NewService(config.ClientName, config.ClientScope,
-		config.ClientWebsite, customCSS, config.SingleInstance,
+		config.ClientWebsite, config.CustomCSS, config.SingleInstance,
 		config.PostFormats, renderer)
 	handler := service.NewHandler(s, *verbose, config.StaticDirectory)
 

mastodon/mastodon.go

@@ -2,18 +2,14 @@
 package mastodon
 
 import (
-	"bytes"
 	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
-	"mime/multipart"
 	"net/http"
 	"net/url"
-	"os"
 	"path"
-	"path/filepath"
 	"strings"
 
 	"github.com/tomnomnom/linkheader"
@@ -61,83 +57,6 @@ func (c *Client) doAPI(ctx context.Context, method string, uri string, params in
 		if err != nil {
 			return err
 		}
-	} else if file, ok := params.(string); ok {
-		f, err := os.Open(file)
-		if err != nil {
-			return err
-		}
-		defer f.Close()
-
-		var buf bytes.Buffer
-		mw := multipart.NewWriter(&buf)
-		part, err := mw.CreateFormFile("file", filepath.Base(file))
-		if err != nil {
-			return err
-		}
-		_, err = io.Copy(part, f)
-		if err != nil {
-			return err
-		}
-		err = mw.Close()
-		if err != nil {
-			return err
-		}
-		req, err = http.NewRequest(method, u.String(), &buf)
-		if err != nil {
-			return err
-		}
-		ct = mw.FormDataContentType()
-	} else if file, ok := params.(*multipart.FileHeader); ok {
-		f, err := file.Open()
-		if err != nil {
-			return err
-		}
-		defer f.Close()
-
-		var buf bytes.Buffer
-		mw := multipart.NewWriter(&buf)
-		fname := filepath.Base(file.Filename)
-		err = mw.WriteField("description", fname)
-		if err != nil {
-			return err
-		}
-		part, err := mw.CreateFormFile("file", fname)
-		if err != nil {
-			return err
-		}
-		_, err = io.Copy(part, f)
-		if err != nil {
-			return err
-		}
-		err = mw.Close()
-		if err != nil {
-			return err
-		}
-		req, err = http.NewRequest(method, u.String(), &buf)
-		if err != nil {
-			return err
-		}
-		ct = mw.FormDataContentType()
-	} else if reader, ok := params.(io.Reader); ok {
-		var buf bytes.Buffer
-		mw := multipart.NewWriter(&buf)
-		part, err := mw.CreateFormFile("file", "upload")
-		if err != nil {
-			return err
-		}
-		_, err = io.Copy(part, reader)
-		if err != nil {
-			return err
-		}
-		err = mw.Close()
-		if err != nil {
-			return err
-		}
-		req, err = http.NewRequest(method, u.String(), &buf)
-		if err != nil {
-			return err
-		}
-		ct = mw.FormDataContentType()
 	} else if mr, ok := params.(*multipartRequest); ok {
 		req, err = http.NewRequest(method, u.String(), mr.Data)
 		if err != nil {
@@ -219,6 +138,16 @@ func (c *Client) AuthenticateToken(ctx context.Context, authCode, redirectURI st
 	return c.authenticate(ctx, params)
 }
 
+func (c *Client) RevokeToken(ctx context.Context) error {
+	params := url.Values{
+		"client_id":     {c.config.ClientID},
+		"client_secret": {c.config.ClientSecret},
+		"token":         {c.GetAccessToken(ctx)},
+	}
+
+	return c.doAPI(ctx, http.MethodPost, "/oauth/revoke", params, nil, nil)
+}
+
 func (c *Client) authenticate(ctx context.Context, params url.Values) error {
 	u, err := url.Parse(c.config.Server)
 	if err != nil {

mastodon/status.go

@@ -1,12 +1,14 @@
 package mastodon
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"io"
 	"mime/multipart"
 	"net/http"
 	"net/url"
+	"path/filepath"
 	"time"
 )
 
@@ -293,30 +295,35 @@ func (c *Client) Search(ctx context.Context, q string, qType string, limit int,
 	return &results, nil
 }
 
-// UploadMedia upload a media attachment from a file.
-func (c *Client) UploadMedia(ctx context.Context, file string) (*Attachment, error) {
-	var attachment Attachment
-	err := c.doAPI(ctx, http.MethodPost, "/api/v1/media", file, &attachment, nil)
-	if err != nil {
-		return nil, err
-	}
-	return &attachment, nil
-}
-
-// UploadMediaFromReader uploads a media attachment from a io.Reader.
-func (c *Client) UploadMediaFromReader(ctx context.Context, reader io.Reader) (*Attachment, error) {
-	var attachment Attachment
-	err := c.doAPI(ctx, http.MethodPost, "/api/v1/media", reader, &attachment, nil)
-	if err != nil {
-		return nil, err
-	}
-	return &attachment, nil
-}
-
-// UploadMediaFromReader uploads a media attachment from a io.Reader.
 func (c *Client) UploadMediaFromMultipartFileHeader(ctx context.Context, fh *multipart.FileHeader) (*Attachment, error) {
+	f, err := fh.Open()
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	var buf bytes.Buffer
+	mw := multipart.NewWriter(&buf)
+	fname := filepath.Base(fh.Filename)
+	err = mw.WriteField("description", fname)
+	if err != nil {
+		return nil, err
+	}
+	part, err := mw.CreateFormFile("file", fname)
+	if err != nil {
+		return nil, err
+	}
+	_, err = io.Copy(part, f)
+	if err != nil {
+		return nil, err
+	}
+	err = mw.Close()
+	if err != nil {
+		return nil, err
+	}
+	params := &multipartRequest{Data: &buf, ContentType: mw.FormDataContentType()}
 	var attachment Attachment
-	err := c.doAPI(ctx, http.MethodPost, "/api/v1/media", fh, &attachment, nil)
+	err = c.doAPI(ctx, http.MethodPost, "/api/v1/media", params, &attachment, nil)
 	if err != nil {
 		return nil, err
 	}

model/session.go

@@ -1,7 +1,6 @@
 package model
 
 type Session struct {
-	ID           string   `json:"id,omitempty"`
 	UserID       string   `json:"uid,omitempty"`
 	Instance     string   `json:"ins,omitempty"`
 	ClientID     string   `json:"cid,omitempty"`
@@ -28,6 +27,7 @@ type Settings struct {
 	AntiDopamineMode      bool   `json:"adm,omitempty"`
 	HideUnsupportedNotifs bool   `json:"hun,omitempty"`
 	CSS                   string `json:"css,omitempty"`
+	CSSHash               string `json:"cssh,omitempty"`
 }
 
 func NewSettings() *Settings {
@@ -44,5 +44,6 @@ func NewSettings() *Settings {
 		AntiDopamineMode:      false,
 		HideUnsupportedNotifs: false,
 		CSS:                   "",
+		CSSHash:               "",
 	}
 }

service/client.go

@@ -34,6 +34,8 @@ func (c *client) setSession(sess *model.Session) error {
 	}
 	http.SetCookie(c.w, &http.Cookie{
 		Name:     "session",
+		Path:     "/",
+		HttpOnly: true,
 		Value:    sb.String(),
 		Expires:  time.Now().Add(365 * 24 * time.Hour),
 	})
@@ -53,6 +55,7 @@ func (c *client) getSession() (sess *model.Session, err error) {
 func (c *client) unsetSession() {
 	http.SetCookie(c.w, &http.Cookie{
 		Name:    "session",
+		Path:    "/",
 		Value:   "",
 		Expires: time.Now(),
 	})

service/service.go

@@ -1,6 +1,8 @@
 package service
 
 import (
+	"crypto/sha256"
+	"encoding/base64"
 	"errors"
 	"fmt"
 	"mime/multipart"
@@ -840,10 +842,6 @@ func (s *service) NewSession(c *client, instance string) (rurl string, sess *mod
 		instanceURL = "https://" + instance
 	}
 
-	sid, err := util.NewSessionID()
-	if err != nil {
-		return
-	}
 	csrf, err := util.NewCSRFToken()
 	if err != nil {
 		return
@@ -859,28 +857,14 @@ func (s *service) NewSession(c *client, instance string) (rurl string, sess *mod
 	if err != nil {
 		return
 	}
+	rurl = app.AuthURI
 	sess = &model.Session{
-		ID:           sid,
 		Instance:     instance,
 		ClientID:     app.ClientID,
 		ClientSecret: app.ClientSecret,
 		CSRFToken:    csrf,
 		Settings:     *model.NewSettings(),
 	}
-
-	u, err := url.Parse("/oauth/authorize")
-	if err != nil {
-		return
-	}
-
-	q := make(url.Values)
-	q.Set("scope", "read write follow")
-	q.Set("client_id", app.ClientID)
-	q.Set("response_type", "code")
-	q.Set("redirect_uri", s.cwebsite+"/oauth_callback")
-	u.RawQuery = q.Encode()
-
-	rurl = instanceURL + u.String()
 	return
 }
 
@@ -902,6 +886,10 @@ func (s *service) Signin(c *client, code string) (err error) {
 	return c.setSession(c.s)
 }
 
+func (s *service) Signout(c *client) (err error) {
+	return c.RevokeToken(c.ctx)
+}
+
 func (s *service) Post(c *client, content string, replyToID string,
 	format string, visibility string, isNSFW bool,
 	files []*multipart.FileHeader) (id string, err error) {
@@ -1028,9 +1016,19 @@ func (s *service) SaveSettings(c *client, settings *model.Settings) (err error)
 	default:
 		return errInvalidArgument
 	}
+	if len(settings.CSS) > 0 {
 		if len(settings.CSS) > 1<<20 {
 			return errInvalidArgument
 		}
+		// For some reason, browsers convert CRLF to LF before calculating
+		// the hash of the inline resources.
+		settings.CSS = strings.Replace(settings.CSS, "\x0d\x0a", "\x0a", -1)
+
+		h := sha256.Sum256([]byte(settings.CSS))
+		settings.CSSHash = base64.StdEncoding.EncodeToString(h[:])
+	} else {
+		settings.CSSHash = ""
+	}
 	c.s.Settings = *settings
 	return c.setSession(c.s)
 }

service/transport.go

@@ -26,6 +26,15 @@ const (
 	CSRF
 )
 
+const csp = "default-src 'none';" +
+	" img-src *;" +
+	" media-src *;" +
+	" font-src *;" +
+	" child-src *;" +
+	" connect-src 'self';" +
+	" script-src 'self';" +
+	" style-src 'self'"
+
 func NewHandler(s *service, verbose bool, staticDir string) http.Handler {
 	r := mux.NewRouter()
 
@@ -58,14 +67,14 @@ func NewHandler(s *service, verbose bool, staticDir string) http.Handler {
 				}(time.Now())
 			}
 
-			var ct string
+			h := c.w.Header()
 			switch rt {
 			case HTML:
-				ct = "text/html; charset=utf-8"
+				h.Set("Content-Type", "text/html; charset=utf-8")
+				h.Set("Content-Security-Policy", csp)
 			case JSON:
-				ct = "application/json"
+				h.Set("Content-Type", "application/json")
 			}
-			c.w.Header().Add("Content-Type", ct)
 
 			err = c.authenticate(at, s.instance)
 			if err != nil {
@@ -73,6 +82,13 @@ func NewHandler(s *service, verbose bool, staticDir string) http.Handler {
 				return
 			}
 
+			// Override the CSP header to allow custom CSS
+			if rt == HTML && len(c.s.Settings.CSS) > 0 &&
+				len(c.s.Settings.CSSHash) > 0 {
+				v := fmt.Sprintf("%s 'sha256-%s'", csp, c.s.Settings.CSSHash)
+				h.Set("Content-Security-Policy", v)
+			}
+
 			err = f(c)
 			if err != nil {
 				writeError(c, err, rt, req.Method == http.MethodGet)
@@ -676,6 +692,10 @@ func NewHandler(s *service, verbose bool, staticDir string) http.Handler {
 	}, CSRF, HTML)
 
 	signout := handle(func(c *client) error {
+		err := s.Signout(c)
+		if err != nil {
+			return err
+		}
 		c.unsetSession()
 		c.redirect("/")
 		return nil

static/fluoride.js

@@ -325,7 +325,7 @@ document.addEventListener("DOMContentLoaded", function() {
 		links[j].target = "_blank";
 	}
 
-	var links = document.querySelectorAll(".status-media-container .img-link");
+	var links = document.querySelectorAll(".status-media-container .img-link, .user-profile-img-container .img-link");
 	for (var j = 0; j < links.length; j++) {
 		handleImgPreview(links[j]);
 	}

templates/header.tmpl

@@ -20,7 +20,7 @@
 	<title> {{if gt .Count 0}}({{.Count}}){{end}} {{.Title}} </title>
 	<link rel="stylesheet" href="/static/style.css">
 	{{if .CustomCSS}}
-	<link rel="stylesheet" href="{{.CustomCSS}}">
+	<link rel="stylesheet" href="/static/{{.CustomCSS}}">
 	{{end}}
 	{{if $.Ctx.FluorideMode}}
 	<script src="/static/fluoride.js"></script>

util/rand.go

@@ -16,10 +16,6 @@ func NewRandID(n int) (string, error) {
 	return enc.EncodeToString(data), nil
 }
 
-func NewSessionID() (string, error) {
-	return NewRandID(24)
-}
-
 func NewCSRFToken() (string, error) {
 	return NewRandID(24)
 }