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-rw-r--r--internal/nametransform/valid.go27
1 files changed, 27 insertions, 0 deletions
diff --git a/internal/nametransform/valid.go b/internal/nametransform/valid.go
new file mode 100644
index 0000000..b991074
--- /dev/null
+++ b/internal/nametransform/valid.go
@@ -0,0 +1,27 @@
+package nametransform
+
+import (
+ "fmt"
+ "strings"
+)
+
+// IsValidName checks if `name` is a valid name for a normal file
+// (does not contain null bytes or "/" etc...).
+func IsValidName(name string) error {
+ if name == "" {
+ return fmt.Errorf("empty input")
+ }
+ if len(name) > NameMax {
+ return fmt.Errorf("too long")
+ }
+ // A name can never contain a null byte or "/". Make sure we never return those
+ // to the kernel, even when we read a corrupted (or fuzzed) filesystem.
+ if strings.Contains(name, "\000") || strings.Contains(name, "/") {
+ return fmt.Errorf("contains forbidden bytes")
+ }
+ // The name should never be "." or "..".
+ if name == "." || name == ".." {
+ return fmt.Errorf(". and .. are forbidden names")
+ }
+ return nil
+}