summary refs log tree commit diff
path: root/profiles/security.nix
blob: 63c5fe4d1ff6b613c10e27235daa398e0d196dc6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
{
  pkgs,
  lib,
  config,
  inputs,
  ...
}: {
  imports = [];
  config = {
    programs.firejail.enable = true;
    security.auditd.enable = true;
    security.audit.enable = true;
    security.audit.rules = [
      "-a exit,always -F arch=b64 -S execve"
    ];

    # https://source.android.com/docs/security/test/scudo
    environment.memoryAllocator.provider = "scudo";
    environment.variables.SCUDO_OPTIONS = "ZeroContents=1";

    security.lockKernelModules = true;
    security.protectKernelImage = true;
    security.allowSimultaneousMultithreading = false;
    security.forcePageTableIsolation = true;

    security.unprivilegedUsernsClone = config.virtualisation.containers.enable;

    security.virtualisation.flushL1DataCache = "always";

    security.apparmor.enable = true;
    security.apparmor.killUnconfinedConfinables = true;

    # Restrict ptrace() usage to processes with a pre-defined relationship
    # (e.g., parent/child)
    boot.kernel.sysctl."kernel.yama.ptrace_scope" = lib.mkOverride 500 1;

    # Hide kptrs even for processes with CAP_SYSLOG
    boot.kernel.sysctl."kernel.kptr_restrict" = lib.mkOverride 500 2;

    # Disable bpf() JIT (to eliminate spray attacks)
    boot.kernel.sysctl."net.core.bpf_jit_enable" = false;

    # Disable ftrace debugging
    boot.kernel.sysctl."kernel.ftrace_enabled" = 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" = true;
    boot.kernel.sysctl."net.ipv4.conf.all.rp_filter" = "1";
    boot.kernel.sysctl."net.ipv4.conf.default.log_martians" = true;
    boot.kernel.sysctl."net.ipv4.conf.default.rp_filter" = "1";

    # Ignore broadcast ICMP (mitigate SMURF)
    boot.kernel.sysctl."net.ipv4.icmp_echo_ignore_broadcasts" = 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" = false;
    boot.kernel.sysctl."net.ipv4.conf.all.secure_redirects" = false;
    boot.kernel.sysctl."net.ipv4.conf.default.accept_redirects" = false;
    boot.kernel.sysctl."net.ipv4.conf.default.secure_redirects" = false;
    boot.kernel.sysctl."net.ipv6.conf.all.accept_redirects" = false;
    boot.kernel.sysctl."net.ipv6.conf.default.accept_redirects" = false;

    # Ignore outgoing ICMP redirects (this is ipv4 only)
    boot.kernel.sysctl."net.ipv4.conf.all.send_redirects" = false;
    boot.kernel.sysctl."net.ipv4.conf.default.send_redirects" = false;

    security.chromiumSuidSandbox.enable = true;

    security.sudo.execWheelOnly = true;
    security.sudo.extraConfig = "Defaults        lecture = never";
  };
}