Add filename conformity check

* Add util function to check a filename for confirming to csaf-v2.0-csd02.
* Add code to reject bad filenames in provider, checker, aggregator and uploader.

Author: s-l-teichmann

cmd/csaf_aggregator/mirror.go

@@ -419,7 +419,13 @@ func (w *worker) mirrorFiles(tlpLabel *csaf.TLPLabel, files []string) error {
 			log.Printf("error: %s\n", err)
 			continue
 		}
-		filename := util.CleanFileName(filepath.Base(u.Path))
+
+		// Ignore not confirming filenames.
+		filename := filepath.Base(u.Path)
+		if !util.ConfirmingFileName(filename) {
+			log.Printf("Not confirming filename %q. Ignoring.\n", filename)
+			continue
+		}
 
 		var advisory interface{}
 

cmd/csaf_checker/processor.go

@@ -22,6 +22,7 @@ import (
 	"log"
 	"net/http"
 	"net/url"
+	"path/filepath"
 	"regexp"
 	"sort"
 	"strconv"
@@ -204,6 +205,7 @@ func (p *processor) checkDomain(domain string) error {
 		(*processor).checkSecurity,
 		(*processor).checkCSAFs,
 		(*processor).checkMissing,
+		(*processor).checkInvalid,
 		(*processor).checkListing,
 		(*processor).checkWellknownMetadataReporter,
 		(*processor).checkDNSPathReporter,
@@ -724,7 +726,29 @@ func (p *processor) checkMissing(string) error {
 	return nil
 }
 
-// checkListing wents over all found adivisories URLs and checks,
+// checkInvalid wents over all found adivisories URLs and checks
+// if file name confirms to standard.
+func (p *processor) checkInvalid(string) error {
+
+	p.badDirListings.use()
+	var invalids []string
+
+	for f := range p.alreadyChecked {
+		if !util.ConfirmingFileName(filepath.Base(f)) {
+			invalids = append(invalids, f)
+		}
+	}
+
+	if len(invalids) > 0 {
+		sort.Strings(invalids)
+		p.badDirListings.add("advisories with invalid file names: %s",
+			strings.Join(invalids, ", "))
+	}
+
+	return nil
+}
+
+// checkListing wents over all found adivisories URLs and checks
 // if their parent directory is listable.
 func (p *processor) checkListing(string) error {
 

cmd/csaf_provider/actions.go

@@ -39,6 +39,10 @@ func (c *controller) loadCSAF(r *http.Request) (string, []byte, error) {
 	}
 	defer file.Close()
 
+	if !util.ConfirmingFileName(handler.Filename) {
+		return "", nil, errors.New("given csaf filename is not confirming")
+	}
+
 	var buf bytes.Buffer
 	if _, err := io.Copy(&buf, c.cfg.uploadLimiter(file)); err != nil {
 		return "", nil, err

cmd/csaf_uploader/main.go

@@ -277,6 +277,10 @@ func (p *processor) uploadRequest(filename string) (*http.Request, error) {
 // It prints the response messages.
 func (p *processor) process(filename string) error {
 
+	if bn := filepath.Base(filename); !util.ConfirmingFileName(bn) {
+		return fmt.Errorf("%q is not a confirming file name", bn)
+	}
+
 	req, err := p.uploadRequest(filename)
 	if err != nil {
 		return err

util/file.go

@@ -19,15 +19,25 @@ import (
 	"time"
 )
 
-var (
-	twoOrMoreDots = regexp.MustCompile(`\.{2,}`)
-	stripSlashes  = strings.NewReplacer(`/`, ``, `\`, ``)
-)
-
-// CleanFileName removes the "/" "\" charachters and replace the two or more
-// occurences of "." with only one from the passed string.
+var invalidRune = regexp.MustCompile(`[^+\-a-z0-9]+`) // invalid runes + `_`
+
+// CleanFileName replaces invalid runes with an underscore and
+// afterwards collapses multiple underscores into one.
+// If the filename does not end with '.json' it will be appended.
+// The filename is converted to lower case.
+// https://docs.oasis-open.org/csaf/csaf/v2.0/csd02/csaf-v2.0-csd02.html#51-filename
+// specifies valid runes as 'a' to 'z', '0' to '9' and '+', '-', '_'.
 func CleanFileName(s string) string {
-	return twoOrMoreDots.ReplaceAllString(stripSlashes.Replace(s), `.`)
+	s = strings.ToLower(s)
+	if strings.HasSuffix(s, ".json") {
+		s = s[:len(s)-len(".json")]
+	}
+	return invalidRune.ReplaceAllString(s, "_") + ".json"
+}
+
+// ConfirmingFileName checks if the given filename is confirming the standard.
+func ConfirmingFileName(fname string) bool {
+	return fname == CleanFileName(fname)
 }
 
 // PathExists returns true if path exits.

util/file_test.go

@@ -5,6 +5,48 @@ import (
 	"testing"
 )
 
+func TestCleanFileName(t *testing.T) {
+	for _, x := range [][2]string{
+		{`HELLO`, `hello.json`},
+		{`hello`, `hello.json`},
+		{`cisco-sa-20190513-secureboot.json`, `cisco-sa-20190513-secureboot.json`},
+		{``, `.json`},
+		{`..`, `_.json`},
+		{`../..`, `_.json`},
+		{`abc.html`, `abc_html.json`},
+		{`abc_.htm__l`, `abc_htm_l.json`},
+		{`foo+BAR`, `foo+bar.json`},
+	} {
+		if got := CleanFileName(x[0]); got != x[1] {
+			t.Errorf("%q: Expected %q but got %q.", x[0], x[1], got)
+		}
+	}
+}
+
+func TestConfirmingFileName(t *testing.T) {
+	for _, x := range []struct {
+		s string
+		b bool
+	}{
+		{`HELLO`, false},
+		{`hello`, false},
+		{`cisco-sa-20190513-secureboot.json`, true},
+		{`example_company_-_2019-yh3234.json`, true},
+		{`rhba-2019_0024.json`, true},
+		{`2022__01-a.json`, false},
+		{``, false},
+		{`..`, false},
+		{`../..`, false},
+		{`abc.html`, false},
+		{`abc_.htm__l`, false},
+		{`foo+BAR`, false},
+	} {
+		if got := ConfirmingFileName(x.s); got != x.b {
+			t.Errorf("%q: Expected %t but got %t.", x.s, x.b, got)
+		}
+	}
+}
+
 func TestNWriter(t *testing.T) {
 
 	msg := []byte("Gruß!\n")