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/nft_payload_cve_2023_0179/skeletonkey_modules.c

@@ -1138,6 +1138,35 @@ static const char nft_payload_sigma[] =
     "level: high\n"
     "tags: [attack.privilege_escalation, attack.t1068, cve.2023.0179]\n";
 
+static const char nft_payload_yara[] =
+    "rule nft_payload_cve_2023_0179 : cve_2023_0179 kernel_oob_read_write\n"
+    "{\n"
+    "    meta:\n"
+    "        cve         = \"CVE-2023-0179\"\n"
+    "        description = \"nft_payload OOB-via-verdict-index breadcrumb log\"\n"
+    "        author      = \"SKELETONKEY\"\n"
+    "    strings:\n"
+    "        $log = \"/tmp/skeletonkey-nft_payload.log\" ascii\n"
+    "    condition:\n"
+    "        $log\n"
+    "}\n";
+
+static const char nft_payload_falco[] =
+    "- rule: nft_payload OOB via verdict-code index by non-root\n"
+    "  desc: |\n"
+    "    Non-root nfnetlink batch with an oversized NFTA_SET_DESC\n"
+    "    + NEWSETELEM whose NFTA_PAYLOAD_SREG uses attacker-\n"
+    "    controlled verdict code as an index into regs->data[].\n"
+    "    CVE-2023-0179.\n"
+    "  condition: >\n"
+    "    evt.type = sendmsg and fd.sockfamily = AF_NETLINK and\n"
+    "    not user.uid = 0\n"
+    "  output: >\n"
+    "    nfnetlink payload batch from non-root\n"
+    "    (user=%user.name pid=%proc.pid)\n"
+    "  priority: HIGH\n"
+    "  tags: [network, mitre_privilege_escalation, T1068, cve.2023.0179]\n";
+
 const struct skeletonkey_module nft_payload_module = {
     .name           = "nft_payload",
     .cve            = "CVE-2023-0179",
@@ -1151,8 +1180,8 @@ const struct skeletonkey_module nft_payload_module = {
     .cleanup        = nft_payload_cleanup,
     .detect_auditd  = nft_payload_auditd,
     .detect_sigma   = nft_payload_sigma,
-    .detect_yara    = NULL,
-    .detect_falco   = NULL,
+    .detect_yara    = nft_payload_yara,
+    .detect_falco   = nft_payload_falco,
     .opsec_notes    = "unshare(CLONE_NEWUSER|CLONE_NEWNET) + nfnetlink batch (NEWTABLE + NEWCHAIN/LOCAL_OUT + NEWSET with oversized NFTA_SET_DESC + NEWSETELEM whose NFTA_PAYLOAD_SREG = attacker verdict code). On packet eval, regs->verdict.code is used unchecked as index into regs->data[] -> OOB. Dual-slab groom (kmalloc-1k + kmalloc-cg-96). Trigger via sendto(AF_INET, 127.0.0.1:31337). Writes /tmp/skeletonkey-nft_payload.log. Audit-visible via unshare + socket(NETLINK_NETFILTER) + sendmsg + msgsnd + socket(AF_INET)/sendto. Cleanup callback unlinks log.",
 };