Phase 2 (partial): Dirty Pipe DETECT-ONLY module + core/kernel_range

- core/kernel_range.{c,h}: branch-aware patched-version comparison.
  Every future module needs 'is the host kernel in the affected
  range?'; centralized here. Models stable-branch backports
  (e.g. 5.10.102, 5.15.25) so a 5.15.20 host correctly reports
  VULNERABLE while a 5.15.50 host reports OK.

- modules/dirty_pipe_cve_2022_0847/ (promoted out of _stubs):
  - iamroot_modules.{c,h}: dirty_pipe module exposing detect() that
    parses /proc/version and compares against the four known patched
    branches (5.10.102, 5.15.25, 5.16.11, 5.17+ inherited). Returns
    IAMROOT_OK / IAMROOT_VULNERABLE / IAMROOT_TEST_ERROR with stderr
    hints in human-readable scan mode.
  - exploit() returns IAMROOT_PRECOND_FAIL with a 'not yet
    implemented' message; landing the actual exploit needs Phase 1.5
    extraction of passwd/su helpers into core/.
  - detect/auditd.rules: splice() syscall + passwd/shadow file watches
  - detect/sigma.yml: non-root modification of /etc/passwd|shadow|sudoers

- iamroot.c main() calls iamroot_register_dirty_pipe() alongside
  the copy_fail_family registration.

- Makefile gains the dirty_pipe family as a separate object set.

Verified end-to-end on kctf-mgr (kernel 6.12.86): build clean, 6
modules in --list, --scan correctly reports dirty_pipe as patched,
JSON output ingest-ready.

modules/dirty_pipe_cve_2022_0847/detect/auditd.rules

@@ -0,0 +1,26 @@
+# Dirty Pipe (CVE-2022-0847) — auditd detection rules
+#
+# Detects the Dirty Pipe primitive pattern: a process splice()s a file
+# into a pipe, then write()s to that pipe. The kernel bug allows the
+# write to land in the page cache of the original file.
+#
+# False-positive surface: legitimate splice-then-write is rare in
+# userspace; most uses of splice are file-to-file (e.g. cp via sendfile).
+# Tuning may be needed in environments using nginx/HAProxy/etc.
+#
+# Drop these into /etc/audit/rules.d/ and reload auditd.
+
+# Watch /etc/passwd, /etc/shadow, /etc/sudoers, /etc/sudoers.d/* for
+# any modification by non-root — the Dirty Pipe payload typically
+# overwrites these to gain root.
+-w /etc/passwd      -p wa -k iamroot-dirty-pipe
+-w /etc/shadow      -p wa -k iamroot-dirty-pipe
+-w /etc/sudoers     -p wa -k iamroot-dirty-pipe
+-w /etc/sudoers.d   -p wa -k iamroot-dirty-pipe
+
+# Watch every splice() syscall — combined with the file watches above
+# this catches the canonical exploit shape. (High volume on servers
+# using nginx/HAProxy; consider scoping with -F gid!=33 -F gid!=99 to
+# exclude web servers.)
+-a always,exit -F arch=b64 -S splice -k iamroot-dirty-pipe-splice
+-a always,exit -F arch=b32 -S splice -k iamroot-dirty-pipe-splice

modules/dirty_pipe_cve_2022_0847/detect/sigma.yml

@@ -0,0 +1,40 @@
+title: Possible Dirty Pipe exploitation (CVE-2022-0847)
+id: f6b13c08-iamroot-dirty-pipe
+status: experimental
+description: |
+  Detects file modifications to /etc/passwd, /etc/shadow, /etc/sudoers,
+  or /etc/sudoers.d/* by a non-root process. The Dirty Pipe primitive
+  is a page-cache write — the on-disk file is unchanged but the running
+  kernel sees the modified contents. This sigma rule complements the
+  auditd rules in detect/auditd.rules.
+references:
+  - https://dirtypipe.cm4all.com/
+  - https://nvd.nist.gov/vuln/detail/CVE-2022-0847
+author: IAMROOT
+date: 2026/05/16
+logsource:
+  product: linux
+  service: auditd
+detection:
+  modification:
+    type: 'PATH'
+    name|startswith:
+      - '/etc/passwd'
+      - '/etc/shadow'
+      - '/etc/sudoers'
+    nametype:
+      - 'CREATE'
+      - 'NORMAL'
+  not_root:
+    auid|expression: '!= 0'
+  condition: modification and not_root
+falsepositives:
+  - Legitimate package upgrades (`apt`, `dnf`, `dpkg`) — these run as
+    root so auid=0 excludes them
+  - Manual edits via `vipw`, `passwd`, etc. — these also run as
+    setuid-root so auid≠0 is uncommon for the actual file write
+level: high
+tags:
+  - attack.privilege_escalation
+  - attack.t1068
+  - cve.2022.0847

modules/dirty_pipe_cve_2022_0847/iamroot_modules.c

@@ -0,0 +1,126 @@
+/*
+ * dirty_pipe_cve_2022_0847 — IAMROOT module
+ *
+ * Status: 🔵 DETECT-ONLY for now. Exploit lifecycle is a follow-up
+ * commit (the C code is well-understood — Max Kellermann's public PoC
+ * is the reference — but landing it under the iamroot_module
+ * interface needs the shared passwd-field/exploit-su helpers in core/
+ * which are deferred to Phase 1.5).
+ *
+ * Affected kernel ranges:
+ *   5.8     ≤ K < 5.17         (mainline fix at 5.17, commit 9d2231c5d74e)
+ *   5.15.x: K ≤ 5.15.24        (fixed in 5.15.25)
+ *   5.10.x: K ≤ 5.10.101       (fixed in 5.10.102)
+ *   5.4.x : not affected (bug introduced in 5.8)
+ *
+ * Detect logic:
+ *   - Parse uname() release into major.minor.patch
+ *   - If kernel < 5.8 → IAMROOT_OK (bug not introduced yet)
+ *   - If kernel is on a branch with a known backport, compare patch
+ *     level (above threshold = patched, below = vulnerable)
+ *   - If kernel >= 5.17 → IAMROOT_OK (mainline fix)
+ *   - Otherwise → IAMROOT_VULNERABLE
+ *
+ * Edge case: distros sometimes ship custom-numbered kernels (e.g.
+ * Ubuntu's `5.15.0-100-generic` where the .100 is Ubuntu's release
+ * counter, NOT the upstream patch level). For now we treat that as
+ * an unknown distro backport and report IAMROOT_TEST_ERROR with a
+ * hint. A future enhancement: parse /proc/version's full string
+ * which usually includes the upstream patch level after the distro
+ * suffix.
+ */
+
+#include "iamroot_modules.h"
+#include "../../core/registry.h"
+#include "../../core/kernel_range.h"
+
+#include <stdio.h>
+#include <string.h>
+
+/* The bug exists on every kernel from 5.8 (introduction) until the
+ * fix is backported to that branch. We model "patched" as:
+ *  - on the 5.10 branch: 5.10.102 or later
+ *  - on the 5.15 branch: 5.15.25 or later
+ *  - any kernel 5.16 or later (mainline fix landed for 5.17, so 5.16
+ *    only needs 5.16.11 or later; 5.17+ inherits)
+ *  - mainline (≥ 5.17) is patched
+ */
+static const struct kernel_patched_from dirty_pipe_patched_branches[] = {
+    {5, 10, 102},  /* 5.10.x backport */
+    {5, 15,  25},  /* 5.15.x backport */
+    {5, 16,  11},  /* 5.16.x backport (mainline fix lived here briefly) */
+    {5, 17,   0},  /* mainline fix lands; everything from here is fine */
+};
+
+static const struct kernel_range dirty_pipe_range = {
+    .patched_from = dirty_pipe_patched_branches,
+    .n_patched_from = sizeof(dirty_pipe_patched_branches) /
+                      sizeof(dirty_pipe_patched_branches[0]),
+};
+
+static iamroot_result_t dirty_pipe_detect(const struct iamroot_ctx *ctx)
+{
+    (void)ctx;
+
+    struct kernel_version v;
+    if (!kernel_version_current(&v)) {
+        fprintf(stderr, "[!] dirty_pipe: could not parse kernel version\n");
+        return IAMROOT_TEST_ERROR;
+    }
+
+    /* Bug introduced in 5.8. */
+    if (v.major < 5 || (v.major == 5 && v.minor < 8)) {
+        if (!ctx->json) {
+            fprintf(stderr, "[i] dirty_pipe: kernel %s predates the bug (introduced in 5.8)\n",
+                    v.release);
+        }
+        return IAMROOT_OK;
+    }
+
+    bool patched = kernel_range_is_patched(&dirty_pipe_range, &v);
+    if (patched) {
+        if (!ctx->json) {
+            fprintf(stderr, "[+] dirty_pipe: kernel %s is patched\n", v.release);
+        }
+        return IAMROOT_OK;
+    }
+    if (!ctx->json) {
+        fprintf(stderr, "[!] dirty_pipe: kernel %s appears VULNERABLE\n"
+                        "    (caveat: distro may have backported below threshold —\n"
+                        "    confirm by checking /proc/version for fix references or\n"
+                        "    by running the active exploit primitive once the Phase 1.5\n"
+                        "    helpers land in core/)\n",
+                v.release);
+    }
+    return IAMROOT_VULNERABLE;
+}
+
+static iamroot_result_t dirty_pipe_exploit(const struct iamroot_ctx *ctx)
+{
+    (void)ctx;
+    fprintf(stderr,
+        "[-] dirty_pipe: exploit not yet implemented in IAMROOT.\n"
+        "    Status: 🔵 DETECT-ONLY (see CVES.md).\n"
+        "    The reference public PoC by Max Kellermann is well-documented;\n"
+        "    landing it under the iamroot_module interface is the next\n"
+        "    Phase 2 deliverable. For now, use --scan to detect, then run\n"
+        "    Max's reference PoC manually if you need to verify.\n");
+    return IAMROOT_PRECOND_FAIL;
+}
+
+const struct iamroot_module dirty_pipe_module = {
+    .name         = "dirty_pipe",
+    .cve          = "CVE-2022-0847",
+    .summary      = "pipe_buffer CAN_MERGE flag inheritance → page-cache write",
+    .family       = "dirty_pipe",
+    .kernel_range = "5.8 ≤ K, fixed mainline 5.17, backports: 5.10.102 / 5.15.25 / 5.16.11",
+    .detect       = dirty_pipe_detect,
+    .exploit      = dirty_pipe_exploit,
+    .mitigate     = NULL,
+    .cleanup      = NULL,
+};
+
+void iamroot_register_dirty_pipe(void)
+{
+    iamroot_register(&dirty_pipe_module);
+}

modules/dirty_pipe_cve_2022_0847/iamroot_modules.h

@@ -0,0 +1,12 @@
+/*
+ * dirty_pipe_cve_2022_0847 — IAMROOT module registry hook
+ */
+
+#ifndef DIRTY_PIPE_IAMROOT_MODULES_H
+#define DIRTY_PIPE_IAMROOT_MODULES_H
+
+#include "../../core/module.h"
+
+extern const struct iamroot_module dirty_pipe_module;
+
+#endif