1 files changed, 118 insertions, 0 deletions
diff --git a/nixos/modules/profiles/hardened.nix b/nixos/modules/profiles/hardened.nix
new file mode 100644
index 00000000000..856ee480fc0
--- /dev/null
+++ b/nixos/modules/profiles/hardened.nix
@@ -0,0 +1,118 @@
+# A profile with most (vanilla) hardening options enabled by default,
+# potentially at the cost of stability, features and performance.
+#
+# This profile enables options that are known to affect system
+# stability. If you experience any stability issues when using the
+# profile, try disabling it. If you report an issue and use this
+# profile, always mention that you do.
+
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+{
+  meta = {
+    maintainers = [ maintainers.joachifm maintainers.emily ];
+  };
+
+  boot.kernelPackages = mkDefault pkgs.linuxPackages_hardened;
+
+  nix.settings.allowed-users = mkDefault [ "@users" ];
+
+  environment.memoryAllocator.provider = mkDefault "scudo";
+  environment.variables.SCUDO_OPTIONS = mkDefault "ZeroContents=1";
+
+  security.lockKernelModules = mkDefault true;
+
+  security.protectKernelImage = mkDefault true;
+
+  security.allowSimultaneousMultithreading = mkDefault false;
+
+  security.forcePageTableIsolation = mkDefault true;
+
+  # This is required by podman to run containers in rootless mode.
+  security.unprivilegedUsernsClone = mkDefault config.virtualisation.containers.enable;
+
+  security.virtualisation.flushL1DataCache = mkDefault "always";
+
+  security.apparmor.enable = mkDefault true;
+  security.apparmor.killUnconfinedConfinables = mkDefault true;
+
+  boot.kernelParams = [
+    # Slab/slub sanity checks, redzoning, and poisoning
+    "slub_debug=FZP"
+
+    # Overwrite free'd memory
+    "page_poison=1"
+
+    # Enable page allocator randomization
+    "page_alloc.shuffle=1"
+  ];
+
+  boot.blacklistedKernelModules = [
+    # Obscure network protocols
+    "ax25"
+    "netrom"
+    "rose"
+
+    # Old or rare or insufficiently audited filesystems
+    "adfs"
+    "affs"
+    "bfs"
+    "befs"
+    "cramfs"
+    "efs"
+    "erofs"
+    "exofs"
+    "freevxfs"
+    "f2fs"
+    "hfs"
+    "hpfs"
+    "jfs"
+    "minix"
+    "nilfs2"
+    "ntfs"
+    "omfs"
+    "qnx4"
+    "qnx6"
+    "sysv"
+    "ufs"
+  ];
+
+  # Restrict ptrace() usage to processes with a pre-defined relationship
+  # (e.g., parent/child)
+  boot.kernel.sysctl."kernel.yama.ptrace_scope" = mkOverride 500 1;
+
+  # Hide kptrs even for processes with CAP_SYSLOG
+  boot.kernel.sysctl."kernel.kptr_restrict" = mkOverride 500 2;
+
+  # Disable bpf() JIT (to eliminate spray attacks)
+  boot.kernel.sysctl."net.core.bpf_jit_enable" = mkDefault false;
+
+  # Disable ftrace debugging
+  boot.kernel.sysctl."kernel.ftrace_enabled" = mkDefault false;
+
+  # Enable strict reverse path filtering (that is, do not attempt to route
+  # packets that "obviously" do not belong to the iface's network; dropped
+  # packets are logged as martians).
+  boot.kernel.sysctl."net.ipv4.conf.all.log_martians" = mkDefault true;
+  boot.kernel.sysctl."net.ipv4.conf.all.rp_filter" = mkDefault "1";
+  boot.kernel.sysctl."net.ipv4.conf.default.log_martians" = mkDefault true;
+  boot.kernel.sysctl."net.ipv4.conf.default.rp_filter" = mkDefault "1";
+
+  # Ignore broadcast ICMP (mitigate SMURF)
+  boot.kernel.sysctl."net.ipv4.icmp_echo_ignore_broadcasts" = mkDefault true;
+
+  # Ignore incoming ICMP redirects (note: default is needed to ensure that the
+  # setting is applied to interfaces added after the sysctls are set)
+  boot.kernel.sysctl."net.ipv4.conf.all.accept_redirects" = mkDefault false;
+  boot.kernel.sysctl."net.ipv4.conf.all.secure_redirects" = mkDefault false;
+  boot.kernel.sysctl."net.ipv4.conf.default.accept_redirects" = mkDefault false;
+  boot.kernel.sysctl."net.ipv4.conf.default.secure_redirects" = mkDefault false;
+  boot.kernel.sysctl."net.ipv6.conf.all.accept_redirects" = mkDefault false;
+  boot.kernel.sysctl."net.ipv6.conf.default.accept_redirects" = mkDefault false;
+
+  # Ignore outgoing ICMP redirects (this is ipv4 only)
+  boot.kernel.sysctl."net.ipv4.conf.all.send_redirects" = mkDefault false;
+  boot.kernel.sysctl."net.ipv4.conf.default.send_redirects" = mkDefault false;
+}