Merge pull request #698 from Elizafox/binarylinter

Add worldwrite linter

pkg/build/linter.go

@@ -36,13 +36,14 @@ type linter struct {
 }
 
 var linterMap = map[string]linter{
-	"dev":       linter{devLinter, "If this package is creating /dev nodes, it should use udev instead; otherwise, remove any files in /dev"},
-	"opt":       linter{optLinter, "This package should be a -compat package"},
-	"setuidgid": linter{isSetUidOrGidLinter, "Unset the setuid/setgid bit on the relevant files, or remove this linter"},
-	"srv":       linter{srvLinter, "This package should be a -compat package"},
-	"tempdir":   linter{tempDirLinter, "Remove any offending files in temporary dirs in the pipeline"},
-	"usrlocal":  linter{usrLocalLinter, "This package should be a -compat package"},
-	"varempty":  linter{varEmptyLinter, "Remove any offending files in /var/empty in the pipeline"},
+	"dev":        linter{devLinter, "If this package is creating /dev nodes, it should use udev instead; otherwise, remove any files in /dev"},
+	"opt":        linter{optLinter, "This package should be a -compat package"},
+	"setuidgid":  linter{isSetUidOrGidLinter, "Unset the setuid/setgid bit on the relevant files, or remove this linter"},
+	"srv":        linter{srvLinter, "This package should be a -compat package"},
+	"tempdir":    linter{tempDirLinter, "Remove any offending files in temporary dirs in the pipeline"},
+	"usrlocal":   linter{usrLocalLinter, "This package should be a -compat package"},
+	"varempty":   linter{varEmptyLinter, "Remove any offending files in /var/empty in the pipeline"},
+	"worldwrite": linter{worldWriteableLinter, "Change the permissions of any world-writeable files in the package, disable the linter, or make this a -compat package"},
 }
 
 var isDevRegex = regexp.MustCompile("^dev/")
@@ -117,6 +118,29 @@ func varEmptyLinter(_ LinterContext, path string, _ fs.DirEntry) error {
 	return nil
 }
 
+func worldWriteableLinter(_ LinterContext, path string, d fs.DirEntry) error {
+	if !d.Type().IsRegular() {
+		// Don't worry about non-files
+		return nil
+	}
+
+	info, err := d.Info()
+	if err != nil {
+		return err
+	}
+
+	mode := info.Mode()
+	if mode&0002 != 0 {
+		if mode&0111 != 0 {
+			return fmt.Errorf("World-writeable executable file found in package (security risk)")
+		} else {
+			return fmt.Errorf("World-writeable file found in package")
+		}
+	}
+
+	return nil
+}
+
 func lintPackageFs(lctx LinterContext, fsys fs.FS, linters []string) error {
 	// If this is a compat package, do nothing.
 	if isCompatPackage.MatchString(lctx.pkgname) {

pkg/build/linter_test.go

@@ -37,7 +37,7 @@ func Test_usrLocalLinter(t *testing.T) {
 			Epoch:   0,
 			Checks: config.Checks{
 				Enabled:  []string{"usrlocal"},
-				Disabled: []string{"dev", "opt", "setuidgid", "srv", "tempdir", "varempty"},
+				Disabled: []string{"dev", "opt", "setuidgid", "srv", "tempdir", "varempty", "worldwrite"},
 			},
 		},
 	}
@@ -66,7 +66,7 @@ func Test_varEmptyLinter(t *testing.T) {
 			Epoch:   0,
 			Checks: config.Checks{
 				Enabled:  []string{"varempty"},
-				Disabled: []string{"dev", "opt", "setuidgid", "srv", "tempdir", "usrlocal"},
+				Disabled: []string{"dev", "opt", "setuidgid", "srv", "tempdir", "usrlocal", "worldwrite"},
 			},
 		},
 	}
@@ -96,7 +96,7 @@ func Test_devLinter(t *testing.T) {
 			Epoch:   0,
 			Checks: config.Checks{
 				Enabled:  []string{"dev"},
-				Disabled: []string{"opt", "setuidgid", "srv", "tempdir", "usrlocal", "varempty"},
+				Disabled: []string{"opt", "setuidgid", "srv", "tempdir", "usrlocal", "varempty", "worldwrite"},
 			},
 		},
 	}
@@ -126,7 +126,7 @@ func Test_optLinter(t *testing.T) {
 			Epoch:   0,
 			Checks: config.Checks{
 				Enabled:  []string{"opt"},
-				Disabled: []string{"dev", "setuidgid", "srv", "tempdir", "usrlocal", "varempty"},
+				Disabled: []string{"dev", "setuidgid", "srv", "tempdir", "usrlocal", "varempty", "worldwrite"},
 			},
 		},
 	}
@@ -156,7 +156,7 @@ func Test_srvLinter(t *testing.T) {
 			Epoch:   0,
 			Checks: config.Checks{
 				Enabled:  []string{"srv"},
-				Disabled: []string{"dev", "opt", "setuidgid", "tempdir", "usrlocal", "varempty"},
+				Disabled: []string{"dev", "opt", "setuidgid", "tempdir", "usrlocal", "varempty", "worldwrite"},
 			},
 		},
 	}
@@ -186,7 +186,7 @@ func Test_tempDirLinter(t *testing.T) {
 			Epoch:   0,
 			Checks: config.Checks{
 				Enabled:  []string{"tempdir"},
-				Disabled: []string{"dev", "opt", "setuidgid", "srv", "usrlocal", "varempty"},
+				Disabled: []string{"dev", "opt", "setuidgid", "srv", "usrlocal", "varempty", "worldwrite"},
 			},
 		},
 	}
@@ -247,7 +247,7 @@ func Test_setUidGidLinter(t *testing.T) {
 			Epoch:   0,
 			Checks: config.Checks{
 				Enabled:  []string{"setuidgid"},
-				Disabled: []string{"dev", "opt", "srv", "tempdir", "usrlocal", "varempty"},
+				Disabled: []string{"dev", "opt", "srv", "tempdir", "usrlocal", "varempty", "worldwrite"},
 			},
 		},
 	}
@@ -271,6 +271,61 @@ func Test_setUidGidLinter(t *testing.T) {
 	assert.Error(t, lintPackageFs(lctx, fsys, linters))
 }
 
+func Test_worldWriteLinter(t *testing.T) {
+	dir, err := os.MkdirTemp("", "melange.XXXXX")
+	defer os.RemoveAll(dir)
+	assert.NoError(t, err)
+
+	cfg := config.Configuration{
+		Package: config.Package{
+			Name:    "test",
+			Version: "4.2.0",
+			Epoch:   0,
+			Checks: config.Checks{
+				Enabled:  []string{"worldwrite"},
+				Disabled: []string{"dev", "opt", "srv", "setuidgid", "tempdir", "usrlocal", "varempty"},
+			},
+		},
+	}
+
+	usrLocalDirPath := filepath.Join(dir, "usr", "lib")
+	err = os.MkdirAll(usrLocalDirPath, 0777)
+	assert.NoError(t, err)
+
+	// Ensure 777 dirs don't trigger it
+	linters := cfg.Package.Checks.GetLinters()
+	assert.Equal(t, linters, []string{"worldwrite"})
+	fsys := os.DirFS(dir)
+	lctx := LinterContext{cfg.Package.Name, &cfg, &cfg.Package.Checks}
+	assert.NoError(t, lintPackageFs(lctx, fsys, linters))
+
+	// Create test file
+	filePath := filepath.Join(usrLocalDirPath, "test.txt")
+	_, err = os.Create(filepath.Join(filePath))
+	assert.NoError(t, err)
+
+	// Set writeable and executable bits for non-world
+	err = os.Chmod(filePath, 0770)
+	assert.NoError(t, err)
+
+	// Linter should not trigger
+	assert.NoError(t, lintPackageFs(lctx, fsys, linters))
+
+	// Set writeable bit (but not executable bit)
+	err = os.Chmod(filePath, 0776)
+	assert.NoError(t, err)
+
+	// Linter should trigger
+	assert.Error(t, lintPackageFs(lctx, fsys, linters))
+
+	// Set writeable and executable bit
+	err = os.Chmod(filePath, 0777)
+	assert.NoError(t, err)
+
+	// Linter should trigger
+	assert.Error(t, lintPackageFs(lctx, fsys, linters))
+}
+
 func Test_disableDefaultLinter(t *testing.T) {
 	dir, err := os.MkdirTemp("", "melange.XXXXX")
 	defer os.RemoveAll(dir)

pkg/config/config.go

@@ -345,6 +345,7 @@ var defaultLinters = []string{
 	"tempdir",
 	"usrlocal",
 	"varempty",
+	"worldwrite",
 }
 
 type VarTransforms struct {