Simon Gardling
a0085187a9
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121 lines
4.0 KiB
Nix
121 lines
4.0 KiB
Nix
{
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config,
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lib,
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pkgs,
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...
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}:
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{
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# memory allocator
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# BREAKS REDIS-IMMICH
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# environment.memoryAllocator.provider = "graphene-hardened";
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# disable coredumps
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systemd.coredump.enable = false;
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# Needed for Nix sandbox UID/GID mapping inside derivation builds.
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# See https://github.com/NixOS/nixpkgs/issues/287194
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security.unprivilegedUsernsClone = true;
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# Disable kexec to prevent replacing the running kernel at runtime.
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security.protectKernelImage = true;
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# Kernel hardening boot parameters. These recover most of the runtime-
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# configurable protections that the linux-hardened patchset provided.
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boot.kernelParams = [
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# Zero all page allocator pages on free / alloc. Prevents info leaks
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# and use-after-free from seeing stale data. Modest CPU overhead.
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"init_on_alloc=1"
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"init_on_free=1"
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# Prevent SLUB allocator from merging caches with similar size/flags.
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# Keeps different kernel object types in separate slabs, making heap
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# exploitation (type confusion, spray, use-after-free) significantly harder.
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"slab_nomerge"
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# Randomize order of pages returned by the buddy allocator.
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"page_alloc.shuffle=1"
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# Disable debugfs entirely (exposes kernel internals).
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"debugfs=off"
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# Disable legacy vsyscall emulation (unused by any modern glibc).
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"vsyscall=none"
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# Strict IOMMU TLB invalidation (no batching). Prevents DMA-capable
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# devices from accessing stale mappings after unmap.
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"iommu.strict=1"
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];
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boot.kernel.sysctl = {
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# Immediately reboot on kernel oops (don't leave a compromised
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# kernel running). Negative value = reboot without delay.
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"kernel.panic" = -1;
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# Hide kernel pointers from all processes, including CAP_SYSLOG.
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# Prevents info leaks used to defeat KASLR.
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"kernel.kptr_restrict" = 2;
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# Disable bpf() JIT compiler (eliminates JIT spray attack vector).
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"net.core.bpf_jit_enable" = false;
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# Disable ftrace (kernel function tracer) at runtime.
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"kernel.ftrace_enabled" = false;
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# Strict reverse-path filtering: drop packets arriving on an interface
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# where the source address isn't routable back via that interface.
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"net.ipv4.conf.all.rp_filter" = 1;
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"net.ipv4.conf.default.rp_filter" = 1;
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"net.ipv4.conf.all.log_martians" = true;
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"net.ipv4.conf.default.log_martians" = true;
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# Ignore ICMP redirects (prevents route table poisoning).
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"net.ipv4.conf.all.accept_redirects" = false;
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"net.ipv4.conf.all.secure_redirects" = false;
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"net.ipv4.conf.default.accept_redirects" = false;
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"net.ipv4.conf.default.secure_redirects" = false;
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"net.ipv6.conf.all.accept_redirects" = false;
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"net.ipv6.conf.default.accept_redirects" = false;
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# Don't send ICMP redirects (we are not a router).
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"net.ipv4.conf.all.send_redirects" = false;
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"net.ipv4.conf.default.send_redirects" = false;
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# Ignore broadcast ICMP (SMURF amplification mitigation).
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"net.ipv4.icmp_echo_ignore_broadcasts" = true;
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# Filesystem hardening: prevent hardlink/symlink-based attacks.
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# protected_hardlinks/symlinks: block unprivileged creation of hard/symlinks
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# to files the user doesn't own (prevents TOCTOU privilege escalation).
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# protected_fifos/regular (level 2): restrict opening FIFOs and regular files
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# in world-writable sticky directories to owner/group match only.
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# Also required for systemd-tmpfiles to chmod hardlinked files.
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"fs.protected_hardlinks" = true;
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"fs.protected_symlinks" = true;
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"fs.protected_fifos" = 2;
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"fs.protected_regular" = 2;
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};
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services = {
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dbus.implementation = "broker";
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/*
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logrotate.enable = true;
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journald = {
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storage = "volatile"; # Store logs in memory
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upload.enable = false; # Disable remote log upload (the default)
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extraConfig = ''
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SystemMaxUse=500M
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SystemMaxFileSize=50M
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'';
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};
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*/
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};
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services.fail2ban = {
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enable = true;
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# Use iptables actions for compatibility
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banaction = "iptables-multiport";
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banaction-allports = "iptables-allports";
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};
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}
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