detection rules: complete sigma/yara/falco coverage across the corpus

Three parallel research agents drafted 49 detection rules grounded in
each module's source + existing .opsec_notes string + existing .detect_auditd
counterpart. A one-shot tools/inject_rules.py wrote them into the
right files and replaced the .detect_<format> = NULL placeholders.

Coverage matrix (modules with each format / 31 total):
                  before        after
  auditd          30 / 31       30 / 31   (entrybleed skipped by design)
  sigma           19 / 31       31 / 31   (+12 added)
  yara            11 / 31       28 / 31   (+17 added; 3 documented skips)
  falco           11 / 31       30 / 31   (+19 added; entrybleed skipped)

Documented skips (kept as .detect_<format> = NULL with comment):
  - entrybleed: yara + falco + auditd. Pure timing side-channel via
    rdtsc + prefetchnta; no syscalls, no file artifacts, no in-memory
    tags. The source comment already noted this; sigma got a 'unusual
    prefetchnta loop time' rule via perf-counter logic.
  - ptrace_traceme: yara. Pure in-memory race; no on-disk artifacts
    or persistent strings to match. Falco + sigma + auditd cover the
    PTRACE_TRACEME + setuid execve syscall sequence.
  - sudo_samedit: yara. Transient heap race during sudoedit invocation;
    no persistent file artifact. Falco + sigma + auditd cover the
    'sudoedit -s + trailing-backslash argv' pattern.

Rule discipline (post-agent QA):
  - All rules ground claims in actual exploit code paths (the agents
    were instructed to read source + opsec_notes; no fabricated syscalls
    or strings).
  - Two falco rules were narrowed by the agent to fire only when
    proc.pname is skeletonkey itself; rewrote both to fire on any
    non-root caller (otherwise we'd detect only our own binary, not
    real attackers).
  - Sigma rule fields use canonical {type: 'SYSCALL', syscall: 'X'}
    detection blocks consistent with existing rules (nf_tables,
    dirty_pipe, sudo_samedit).
  - YARA rules prefer rare/unique tags (SKELETONKEYU, SKELETONKEY_FWD,
    SKVMWGFX, /tmp/skeletonkey-*.log) over common bytes — minimizes
    false positives.
  - Every rule tagged with attack.privilege_escalation + cve.YYYY.NNNN;
    cgroup_release_agent additionally tagged T1611 (container escape).

skeletonkey.c: --module-info text view now dumps yara + falco rule
bodies too (was auditd + sigma only). All 4 formats visible per module.

Verification:
  - macOS local: clean build, 33 kernel_range tests pass.
  - Linux (docker gcc:latest): 33 + 54 = 87 passes, 0 fails.
  - --module-info nf_tables / af_unix_gc / etc.: 'detect rules:'
    summary correctly shows all 4 formats and the bodies print.

modules/cgroup_release_agent_cve_2022_0492/skeletonkey_modules.c

@@ -359,6 +359,36 @@ static const char cgroup_ra_sigma[] =
     "level: high\n"
     "tags: [attack.privilege_escalation, attack.t1611, cve.2022.0492]\n";
 
+static const char cgroup_release_agent_yara[] =
+    "rule cgroup_release_agent_cve_2022_0492 : cve_2022_0492 container_escape\n"
+    "{\n"
+    "    meta:\n"
+    "        cve         = \"CVE-2022-0492\"\n"
+    "        description = \"cgroup v1 release_agent payload + dropped setuid shell artifacts\"\n"
+    "        author      = \"SKELETONKEY\"\n"
+    "    strings:\n"
+    "        $payload = \"/tmp/skeletonkey-cgroup-payload.sh\" ascii\n"
+    "        $shell   = \"/tmp/skeletonkey-cgroup-sh\" ascii\n"
+    "        $mnt     = \"/tmp/skeletonkey-cgroup-mnt\" ascii\n"
+    "    condition:\n"
+    "        any of them\n"
+    "}\n";
+
+static const char cgroup_release_agent_falco[] =
+    "- rule: cgroup v1 mount by non-root with release_agent write\n"
+    "  desc: |\n"
+    "    A non-root process inside a userns mounts cgroup v1 and\n"
+    "    writes to a release_agent file. CVE-2022-0492 trigger:\n"
+    "    release_agent runs as init-ns root when cgroup empties.\n"
+    "  condition: >\n"
+    "    evt.type = mount and evt.arg.fstype = cgroup and\n"
+    "    not user.uid = 0\n"
+    "  output: >\n"
+    "    cgroup v1 mount by non-root\n"
+    "    (user=%user.name pid=%proc.pid target=%evt.arg.name)\n"
+    "  priority: CRITICAL\n"
+    "  tags: [container, mitre_privilege_escalation, T1611, cve.2022.0492]\n";
+
 const struct skeletonkey_module cgroup_release_agent_module = {
     .name           = "cgroup_release_agent",
     .cve            = "CVE-2022-0492",
@@ -371,8 +401,8 @@ const struct skeletonkey_module cgroup_release_agent_module = {
     .cleanup        = cgroup_ra_cleanup,
     .detect_auditd  = cgroup_ra_auditd,
     .detect_sigma   = cgroup_ra_sigma,
-    .detect_yara    = NULL,
-    .detect_falco   = NULL,
+    .detect_yara    = cgroup_release_agent_yara,
+    .detect_falco   = cgroup_release_agent_falco,
     .opsec_notes    = "unshare(CLONE_NEWUSER|CLONE_NEWNS), mount cgroup v1 at /tmp/skeletonkey-cgroup-mnt, write payload path to release_agent file at cgroup root, echo 1 to notify_on_release in subdir, add PID to cgroup.procs and exit. Payload at /tmp/skeletonkey-cgroup-payload.sh runs as init-namespace root when cgroup empties, dropping setuid /tmp/skeletonkey-cgroup-sh. Audit-visible via unshare + mount(cgroup) + open/write of release_agent. Cleanup callback removes /tmp/skeletonkey-cgroup-* and umounts.",
 };