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[Hardening] Fix many issues, use new cmdline custom option

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This commit is contained in:
Antoine Viallon 2022-04-08 21:16:44 +02:00
parent 5e47d0e724
commit 54d899103d
Signed by: aviallon
GPG key ID: 186FC35EDEB25716
1 changed files with 34 additions and 14 deletions
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48
hardening.nix
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@ -45,43 +45,63 @@ in
security.lockKernelModules = mkIf cfg.hardcore (mkOverride 500 true);
# security.protectKernelImage = mkIf cfg.hardcore (mkOverride 500 false); # needed for kexec
aviallon.hardening.expensive = mkForce cfg.hardcore;
aviallon.hardening.expensive = mkIf cfg.hardcore (mkForce true);
services.openssh.permitRootLogin = "prohibit-password";
security.apparmor.enable = true;
services.dbus.apparmor = "enabled";
aviallon.boot.cmdline = {
"lsm" = [ "landlock" ]
++ optional cfg.hardcore "lockdown"
# Apparmor https://wiki.archlinux.org/title/AppArmor#Installation
++ optionals config.security.apparmor.enable [ "apparmor" ]
++ [ "yama" ]
++ [ "bpf" ]
;
"lockdown" = if cfg.hardcore then "confidentiality" else "integrity";
boot.kernelParams = mkAfter (concatLists [
# Vsyscall page not readable (default is "emulate". "none" might break statically-linked binaries.)
vsyscall = mkIf cfg.hardcore "xonly";
} // (ifEnable cfg.expensive {
# Slab/slub sanity checks, redzoning, and poisoning
(optional cfg.expensive "slub_debug=FZP")
"slub_debug" = "FZP";
# Overwrite free'd memory
(optional cfg.expensive "page_poison=1")
"page_poison" = 1;
# Enable page allocator randomization
[ "page_alloc.shuffle=1" ]
"page_alloc.shuffle" = 1;
# Apparmor https://wiki.archlinux.org/title/AppArmor#Installation
(optional cfg.expensive "lsm=landlock,lockdown,yama,apparmor,bpf")
]);
"nordrand" = "";
"random.trust_cpu" = "off";
});
boot.kernel.sysctl = {
"kernel.yama.ptrace_scope" = mkOverride 500 1;
"kernel.kptr_restrict" = mkOverride 500 2;
# Almost free security. https://www.kernel.org/doc/html/latest/admin-guide/LSM/Yama.html
"kernel.yama.ptrace_scope" = mkOverride 999 1;
"net.core.bpf_jit_enable" = mkIf cfg.expensive (mkOverride 500 false);
# https://lwn.net/Articles/420403/
"kernel.kptr_restrict" = mkOverride 999 2;
"kernel.ftrace_enabled" = mkOverride 500 false;
# Can have dire impact on performance if BPF network filtering is used.
"net.core.bpf_jit_enable" = mkIf cfg.expensive (mkOverride 999 false);
# Can be used by developers. Should be disabled on regular desktops.
# https://www.kernel.org/doc/html/latest/trace/ftrace.html
"kernel.ftrace_enabled" = mkIf cfg.hardcore (mkOverride 999 false);
};
# Is used in podman containers, for instance
security.allowUserNamespaces = mkDefault true;
# boot.blacklistedKernelModules = mkForce [ ];
nix.allowedUsers = mkIf cfg.hardcore [ "@wheel" ];
# Only authorize admins to use nix in hardcore mode
nix.allowedUsers = mkIf cfg.hardcore (mkForce [ "@wheel" ]);
security.audit.enable = true;
# Can really badly affect performance in some occasions.
security.audit.enable = mkIf cfg.expensive true;
security.auditd.enable = mkIf cfg.expensive true;
security.audit.rules = concatLists [