verify-vm: per-module provisioner hook + old-mainline URL fallback

Adds tools/verify-vm/provisioners/<module>.sh hook so per-module setup
(build vulnerable sudo from source, drop polkit allow rule, add sudoers
grant) lives in checked-in scripts rather than manual VM steps. Vagrantfile
runs the script as root before build-and-verify if it exists.

Also fixes mainline kernel fetch to fall back from /v${KVER}/amd64/ to
/v${KVER}/ for old kernels (≤ ~4.15) where debs aren't under the amd64
subdir, and accepts both 'linux-image-' (old) and 'linux-image-unsigned-'
(new) deb names.

Wires up 4 previously-deferred targets to expect VULNERABLE:
- sudo_chwoot: builds sudo 1.9.16p1 from upstream into /usr/local
- udisks_libblockdev: installs udisks2 + polkit rule for vagrant user
- mutagen_astronomy: pins mainline 4.14.70 (one below the .71 fix)
- sudo_runas_neg1: adds (ALL,!root) sudoers grant

tools/verify-vm/provisioners/sudo_chwoot.sh

@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+# CVE-2025-32463 sudo --chroot NSS injection (Stratascale). Vulnerable
+# range is sudo [1.9.14, 1.9.17p0]. Ubuntu 22.04 ships 1.9.9 which
+# PREDATES the --chroot code path. Build sudo 1.9.16p1 from upstream
+# and install to /usr/local (which precedes /usr/bin in Ubuntu's default
+# PATH so plain `sudo` resolves to the vulnerable binary).
+set -e
+
+export DEBIAN_FRONTEND=noninteractive
+apt-get install -y -qq libpam0g-dev libssl-dev wget make gcc >/dev/null
+
+cd /tmp
+TARBALL=sudo-1.9.16p1.tar.gz
+URL="https://www.sudo.ws/dist/${TARBALL}"
+
+if [ -x /usr/local/bin/sudo ] && /usr/local/bin/sudo --version 2>&1 | head -1 | grep -q "1.9.16p1"; then
+    echo "[=] sudo 1.9.16p1 already at /usr/local/bin/sudo"
+else
+    [ -f "${TARBALL}" ] || wget -q "${URL}"
+    rm -rf sudo-1.9.16p1
+    tar xzf "${TARBALL}"
+    cd sudo-1.9.16p1
+    # --sysconfdir=/etc so it honors the existing /etc/sudoers (vagrant's
+    # NOPASSWD grant). --disable-shared keeps the build self-contained.
+    ./configure --prefix=/usr/local --sysconfdir=/etc \
+        --disable-shared --quiet >/dev/null 2>&1
+    make -j"$(nproc)" >/tmp/sudo-build.log 2>&1 || { tail -40 /tmp/sudo-build.log; exit 1; }
+    make install >/tmp/sudo-install.log 2>&1 || { tail -40 /tmp/sudo-install.log; exit 1; }
+fi
+
+# Verify what the unprivileged user's PATH resolves to.
+echo "[+] which sudo (root): $(which sudo)"
+echo "[+] /usr/local/bin/sudo version: $(/usr/local/bin/sudo --version | head -1)"
+sudo -u vagrant bash -c 'echo "[+] vagrant PATH: $PATH"; echo "[+] vagrant sees: $(which sudo)"; sudo --version | head -1'

tools/verify-vm/provisioners/sudo_runas_neg1.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+# CVE-2019-14287 needs a (ALL,!root) grant for find_runas_blacklist_grant()
+# to fire. Ubuntu 18.04 ships sudo 1.8.21p2 (in the vulnerable range) but
+# Vagrant's default sudoers doesn't include the grant. Add it.
+set -e
+
+cat >/etc/sudoers.d/99-skk-runas-neg1 <<'EOF'
+vagrant ALL=(ALL,!root) NOPASSWD: /bin/vi
+EOF
+chmod 0440 /etc/sudoers.d/99-skk-runas-neg1
+
+echo "[+] sudoers grant installed:"
+grep . /etc/sudoers.d/99-skk-runas-neg1
+echo
+echo "[+] sudo -ln -U vagrant tail:"
+sudo -ln -U vagrant 2>&1 | tail -10 || true

tools/verify-vm/provisioners/udisks_libblockdev.sh

@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+# CVE-2025-6019 udisks/libblockdev SUID-on-mount (Qualys). Debian 12's
+# cloud image is server-oriented and doesn't ship udisks2. Install it,
+# and drop a polkit rule allowing the vagrant user to invoke the
+# affected action.ids — the real-world bug-path is "active console
+# user invokes loop-setup", and we don't have a graphical session in
+# Vagrant. The polkit rule simulates the trust polkit would give a
+# logged-in workstation user.
+set -e
+
+export DEBIAN_FRONTEND=noninteractive
+apt-get install -y -qq udisks2 libblockdev-utils3 >/dev/null
+
+mkdir -p /etc/polkit-1/rules.d
+cat >/etc/polkit-1/rules.d/49-skk-verify.rules <<'EOF'
+polkit.addRule(function(action, subject) {
+    if (subject.user == "vagrant" &&
+        (action.id == "org.freedesktop.UDisks2.loop-setup" ||
+         action.id == "org.freedesktop.UDisks2.filesystem-mount" ||
+         action.id == "org.freedesktop.UDisks2.filesystem-mount-other-seat" ||
+         action.id == "org.freedesktop.UDisks2.modify-device")) {
+        return polkit.Result.YES;
+    }
+});
+EOF
+
+systemctl enable udisks2.service >/dev/null 2>&1 || true
+systemctl restart udisks2.service
+sleep 2
+
+echo "[+] udisks2 status:"
+systemctl is-active udisks2.service
+echo "[+] udisks2 version: $(dpkg-query -W -f='${Version}' udisks2)"
+echo "[+] libblockdev version: $(dpkg-query -W -f='${Version}' libblockdev-utils3 2>/dev/null || dpkg-query -W -f='${Version}' libblockdev-utils2)"