feat: enforce CHFS permissions in WebDAV

chfs-ng/internal/api/server.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"archive/zip"
+	"context"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -598,21 +599,106 @@ func (s *Server) webdav(w http.ResponseWriter, r *http.Request) {
 		http.NotFound(w, r)
 		return
 	}
-	vp := strings.TrimPrefix(r.URL.Path, "/webdav")
-	vp = strings.Trim(vp, "/")
-	if !account(r, s).MaskFor(vp).HasRead() {
-		http.Error(w, "forbidden", 403)
-		return
-	}
-	if r.Method != http.MethodGet && r.Method != http.MethodHead && !account(r, s).MaskFor(vp).HasWrite() {
-		http.Error(w, "forbidden", 403)
-		return
-	}
+	vp := strings.Trim(strings.TrimPrefix(r.URL.Path, "/webdav"), "/")
 	old := r.URL.Path
 	r.URL.Path = "/" + vp
 	defer func() { r.URL.Path = old }()
-	h := &webdav.Handler{FileSystem: webdav.LocalFileSystem(s.WebDAVRoot)}
-	h.ServeHTTP(w, r)
+	fs := &webdavAuthFS{inner: webdav.LocalFileSystem(s.WebDAVRoot), account: account(r, s)}
+	(&webdav.Handler{FileSystem: fs}).ServeHTTP(w, r)
+}
+
+type webdavAuthFS struct {
+	inner   webdav.FileSystem
+	account *auth.Account
+}
+
+func (f *webdavAuthFS) allow(path string, p auth.PermMask) error {
+	path = strings.Trim(path, "/")
+	if f.account == nil || f.account.MaskFor(path)&p != p {
+		return webdav.NewHTTPError(http.StatusForbidden, fmt.Errorf("forbidden"))
+	}
+	return nil
+}
+func (f *webdavAuthFS) Open(ctx context.Context, name string) (io.ReadCloser, error) {
+	if err := f.allow(name, auth.Read); err != nil {
+		return nil, err
+	}
+	return f.inner.Open(ctx, name)
+}
+func (f *webdavAuthFS) Stat(ctx context.Context, name string) (*webdav.FileInfo, error) {
+	if err := f.allow(name, auth.Read); err != nil {
+		return nil, err
+	}
+	return f.inner.Stat(ctx, name)
+}
+func (f *webdavAuthFS) ReadDir(ctx context.Context, name string, recursive bool) ([]webdav.FileInfo, error) {
+	if err := f.allow(name, auth.Read); err != nil {
+		return nil, err
+	}
+	items, err := f.inner.ReadDir(ctx, name, recursive)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]webdav.FileInfo, 0, len(items))
+	for _, item := range items {
+		p := strings.Trim(item.Path, "/")
+		if f.account.MaskFor(p).HasRead() {
+			out = append(out, item)
+		}
+	}
+	return out, nil
+}
+func (f *webdavAuthFS) Create(ctx context.Context, name string, body io.ReadCloser, opts *webdav.CreateOptions) (*webdav.FileInfo, bool, error) {
+	parent := path.Dir(strings.Trim(name, "/"))
+	if parent == "." {
+		parent = ""
+	}
+	if err := f.allow(parent, auth.Write); err != nil {
+		return nil, false, err
+	}
+	return f.inner.Create(ctx, name, body, opts)
+}
+func (f *webdavAuthFS) RemoveAll(ctx context.Context, name string, opts *webdav.RemoveAllOptions) error {
+	if err := f.allow(name, auth.Delete); err != nil {
+		return err
+	}
+	return f.inner.RemoveAll(ctx, name, opts)
+}
+func (f *webdavAuthFS) Mkdir(ctx context.Context, name string) error {
+	parent := path.Dir(strings.Trim(name, "/"))
+	if parent == "." {
+		parent = ""
+	}
+	if err := f.allow(parent, auth.Write); err != nil {
+		return err
+	}
+	return f.inner.Mkdir(ctx, name)
+}
+func (f *webdavAuthFS) Copy(ctx context.Context, name, dest string, opts *webdav.CopyOptions) (bool, error) {
+	if err := f.allow(name, auth.Read); err != nil {
+		return false, err
+	}
+	parent := path.Dir(strings.Trim(dest, "/"))
+	if parent == "." {
+		parent = ""
+	}
+	if err := f.allow(parent, auth.Write); err != nil {
+		return false, err
+	}
+	return f.inner.Copy(ctx, name, dest, opts)
+}
+func (f *webdavAuthFS) Move(ctx context.Context, name, dest string, opts *webdav.MoveOptions) (bool, error) {
+	if err := f.allow(name, auth.Write); err != nil {
+		return false, err
+	}
+	parent := path.Dir(strings.Trim(dest, "/"))
+	if parent == "." {
+		parent = ""
+	}
+	if err := f.allow(parent, auth.Write); err != nil {
+		return false, err
+	}
+	return f.inner.Move(ctx, name, dest, opts)
 }
 
 func (s *Server) ipFilter(next http.Handler) http.Handler {