[Backport #1801] Sensitive path usage in templatefile shouldn't panic (#1846)

Signed-off-by: James Humphries <james@james-humphries.co.uk>

CHANGELOG.md

@@ -34,7 +34,7 @@ BUG FIXES:
 * Fixed issue with migration between versions can cause an update in-place for resources when no changes are needed. ([#1640](https://github.com/opentofu/opentofu/pull/1640))
 * Add source context for the 'insufficient feature blocks' error ([#1777](https://github.com/opentofu/opentofu/pull/1777))
 * Remove encryption diags from autocomplete ([#1793](https://github.com/opentofu/opentofu/pull/1793))
-
+* Ensure that using a sensitive path for templatefile that it doesn't panic([#1801](https://github.com/opentofu/opentofu/issues/1801))
 
 ## Previous Releases
 

internal/lang/funcs/filesystem.go

@@ -121,7 +121,6 @@ func MakeTemplateFileFunc(baseDir string, funcsCb func() map[string]function.Fun
 	return makeTemplateFileFuncImpl(baseDir, funcsCb, 0)
 }
 func makeTemplateFileFuncImpl(baseDir string, funcsCb func() map[string]function.Function, depth int) function.Function {
-
 	params := []function.Parameter{
 		{
 			Name:        "path",
@@ -134,7 +133,7 @@ func makeTemplateFileFuncImpl(baseDir string, funcsCb func() map[string]function
 		},
 	}
 
-	loadTmpl := func(fn string, marks cty.ValueMarks) (hcl.Expression, error) {
+	loadTmpl := func(path string, marks cty.ValueMarks) (hcl.Expression, error) {
 		maxDepth, err := templateMaxRecursionDepth()
 		if err != nil {
 			return nil, err
@@ -146,12 +145,15 @@ func makeTemplateFileFuncImpl(baseDir string, funcsCb func() map[string]function
 
 		// We re-use File here to ensure the same filename interpretation
 		// as it does, along with its other safety checks.
-		tmplVal, err := File(baseDir, cty.StringVal(fn).WithMarks(marks))
+		templateValue, err := File(baseDir, cty.StringVal(path).WithMarks(marks))
 		if err != nil {
 			return nil, err
 		}
 
-		expr, diags := hclsyntax.ParseTemplate([]byte(tmplVal.AsString()), fn, hcl.Pos{Line: 1, Column: 1})
+		// unmark the template ready to be handled
+		templateValue, _ = templateValue.Unmark()
+
+		expr, diags := hclsyntax.ParseTemplate([]byte(templateValue.AsString()), path, hcl.Pos{Line: 1, Column: 1})
 		if diags.HasErrors() {
 			return nil, diags
 		}
@@ -206,7 +208,6 @@ func makeTemplateFileFuncImpl(baseDir string, funcsCb func() map[string]function
 			return result.WithMarks(pathMarks), err
 		},
 	})
-
 }
 
 // MakeFileExistsFunc constructs a function that takes a path

internal/lang/funcs/filesystem_test.go

@@ -6,16 +6,18 @@
 package funcs
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
 	"testing"
 
 	homedir "github.com/mitchellh/go-homedir"
-	"github.com/opentofu/opentofu/internal/lang/marks"
 	"github.com/zclconf/go-cty/cty"
 	"github.com/zclconf/go-cty/cty/function"
 	"github.com/zclconf/go-cty/cty/function/stdlib"
+
+	"github.com/opentofu/opentofu/internal/lang/marks"
 )
 
 func TestFile(t *testing.T) {
@@ -181,6 +183,21 @@ func TestTemplateFile(t *testing.T) {
 			cty.True, // since this template contains only an interpolation, its true value shines through
 			``,
 		},
+		{
+			// write to a sensitive file path that exists
+			cty.StringVal("testdata/hello.txt").Mark(marks.Sensitive),
+			cty.EmptyObjectVal,
+			cty.StringVal("Hello World").Mark(marks.Sensitive),
+			``,
+		},
+		{
+			cty.StringVal("testdata/bare.tmpl"),
+			cty.ObjectVal(map[string]cty.Value{
+				"val": cty.True.Mark(marks.Sensitive),
+			}),
+			cty.True.Mark(marks.Sensitive),
+			``,
+		},
 	}
 
 	templateFileFn := MakeTemplateFileFunc(".", func() map[string]function.Function {
@@ -194,7 +211,8 @@ func TestTemplateFile(t *testing.T) {
 		t.Run(fmt.Sprintf("TemplateFile(%#v, %#v)", test.Path, test.Vars), func(t *testing.T) {
 			got, err := templateFileFn.Call([]cty.Value{test.Path, test.Vars})
 
-			if argErr, ok := err.(function.ArgError); ok {
+			var argErr function.ArgError
+			if errors.As(err, &argErr) {
 				if argErr.Index < 0 || argErr.Index > 1 {
 					t.Errorf("ArgError index %d is out of range for templatefile (must be 0 or 1)", argErr.Index)
 				}