fix(sandbox): support symlinked SSH dirs and canonicalize test candidates

Compare os.Stat instead of os.Lstat during SSH root directory walk so
symlinked directory roots match root.Stat without failing closed as
unexpected replacements. Canonicalize both entry and target in denyCovered
to correctly handle macOS /private/var and Windows 8.3 short-path aliases.

Refs #815

Author: euxaristia

internal/sandbox/ssh_gpg_deny_test.go

@@ -12,8 +12,15 @@ import (
 
 func denyCovered(denied []string, target string) bool {
 	norm := normalizeProfilePath(target)
+	if norm == "" {
+		norm = filepath.Clean(target)
+	}
 	for _, entry := range denied {
-		if entry == norm || pathWithinRoot(entry, norm) {
+		normEntry := normalizeProfilePath(entry)
+		if normEntry == "" {
+			normEntry = filepath.Clean(entry)
+		}
+		if normEntry == norm || pathWithinRoot(normEntry, norm) {
 			return true
 		}
 	}

internal/sandbox/ssh_key_deny.go

@@ -127,7 +127,7 @@ func (s *sshDiscovery) walkPrivateKeyFiles(sshDir string) []string {
 				testSSHWalkChildHook(dir)
 			}
 			// Verify directory identity has not changed since opening root.
-			dirStat, statErr := os.Lstat(dir)
+			dirStat, statErr := os.Stat(dir)
 			if statErr != nil || !os.SameFile(dirStat, rootStat) {
 				s.fail(dir, "directory identity changed during inspection")
 				return