2017-04-06 13:54:45 +01:00
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# A profile with most (vanilla) hardening options enabled by default,
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# potentially at the cost of features and performance.
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2018-07-20 21:56:59 +01:00
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{ lib, pkgs, ... }:
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2017-04-06 13:54:45 +01:00
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with lib;
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{
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2018-10-14 23:18:33 +01:00
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meta = {
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maintainers = [ maintainers.joachifm ];
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};
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2017-04-30 00:22:32 +01:00
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boot.kernelPackages = mkDefault pkgs.linuxPackages_hardened;
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2018-11-24 14:13:03 +00:00
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nix.allowedUsers = mkDefault [ "@users" ];
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2019-11-19 09:26:49 +00:00
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environment.memoryAllocator.provider = mkDefault "scudo";
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environment.variables.SCUDO_OPTIONS = mkDefault "ZeroContents=1";
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2017-04-06 13:54:45 +01:00
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security.hideProcessInformation = mkDefault true;
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2017-04-29 21:46:20 +01:00
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security.lockKernelModules = mkDefault true;
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2018-10-14 23:39:26 +01:00
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security.allowUserNamespaces = mkDefault false;
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2018-12-16 09:37:36 +00:00
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security.protectKernelImage = mkDefault true;
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2018-12-26 21:24:04 +00:00
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security.allowSimultaneousMultithreading = mkDefault false;
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2019-07-30 01:24:56 +01:00
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security.forcePageTableIsolation = mkDefault true;
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2019-07-19 14:49:37 +01:00
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security.virtualisation.flushL1DataCache = mkDefault "always";
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2018-12-26 21:22:55 +00:00
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2017-04-06 13:54:45 +01:00
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security.apparmor.enable = mkDefault true;
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2017-04-29 16:27:08 +01:00
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boot.kernelParams = [
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2019-01-05 12:47:25 +00:00
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# Slab/slub sanity checks, redzoning, and poisoning
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"slub_debug=FZP"
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# Disable slab merging to make certain heap overflow attacks harder
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"slab_nomerge"
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2017-04-30 00:22:32 +01:00
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# Overwrite free'd memory
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"page_poison=1"
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2017-04-29 16:27:08 +01:00
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# Disable legacy virtual syscalls
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"vsyscall=none"
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2019-08-15 17:24:24 +01:00
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# Enable page allocator randomization
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"page_alloc.shuffle=1"
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2017-04-29 16:27:08 +01:00
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];
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2017-09-03 00:49:01 +01:00
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boot.blacklistedKernelModules = [
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# Obscure network protocols
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"ax25"
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"netrom"
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"rose"
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2019-10-12 11:08:44 +01:00
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# Old or rare or insufficiently audited filesystems
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"adfs"
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"affs"
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"bfs"
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"befs"
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"cramfs"
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"efs"
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"erofs"
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"exofs"
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"freevxfs"
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"f2fs"
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"hfs"
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"hpfs"
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"jfs"
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"minix"
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"nilfs2"
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"qnx4"
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"qnx6"
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"sysv"
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"ufs"
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2017-09-03 00:49:01 +01:00
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];
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2017-04-06 13:54:45 +01:00
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# Restrict ptrace() usage to processes with a pre-defined relationship
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# (e.g., parent/child)
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boot.kernel.sysctl."kernel.yama.ptrace_scope" = mkOverride 500 1;
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# Restrict access to kernel ring buffer (information leaks)
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boot.kernel.sysctl."kernel.dmesg_restrict" = mkDefault true;
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# Hide kptrs even for processes with CAP_SYSLOG
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boot.kernel.sysctl."kernel.kptr_restrict" = mkOverride 500 2;
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# Unprivileged access to bpf() has been used for privilege escalation in
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# the past
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boot.kernel.sysctl."kernel.unprivileged_bpf_disabled" = mkDefault true;
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# Disable bpf() JIT (to eliminate spray attacks)
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boot.kernel.sysctl."net.core.bpf_jit_enable" = mkDefault false;
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# ... or at least apply some hardening to it
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boot.kernel.sysctl."net.core.bpf_jit_harden" = mkDefault true;
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2017-04-30 13:41:56 +01:00
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2017-08-12 23:17:43 +01:00
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# Raise ASLR entropy for 64bit & 32bit, respectively.
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#
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# Note: mmap_rnd_compat_bits may not exist on 64bit.
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boot.kernel.sysctl."vm.mmap_rnd_bits" = mkDefault 32;
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boot.kernel.sysctl."vm.mmap_rnd_compat_bits" = mkDefault 16;
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2017-09-03 00:48:46 +01:00
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# Allowing users to mmap() memory starting at virtual address 0 can turn a
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# NULL dereference bug in the kernel into code execution with elevated
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# privilege. Mitigate by enforcing a minimum base addr beyond the NULL memory
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# space. This breaks applications that require mapping the 0 page, such as
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# dosemu or running 16bit applications under wine. It also breaks older
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# versions of qemu.
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#
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# The value is taken from the KSPP recommendations (Debian uses 4096).
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boot.kernel.sysctl."vm.mmap_min_addr" = mkDefault 65536;
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2019-07-04 17:50:48 +01:00
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# Disable ftrace debugging
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boot.kernel.sysctl."kernel.ftrace_enabled" = mkDefault false;
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2019-07-04 17:51:06 +01:00
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2019-08-11 12:32:24 +01:00
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# Enable strict reverse path filtering (that is, do not attempt to route
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# packets that "obviously" do not belong to the iface's network; dropped
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# packets are logged as martians).
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2019-07-04 17:51:06 +01:00
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boot.kernel.sysctl."net.ipv4.conf.all.log_martians" = mkDefault true;
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2019-08-11 12:32:24 +01:00
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boot.kernel.sysctl."net.ipv4.conf.all.rp_filter" = mkDefault "1";
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2019-07-04 17:51:06 +01:00
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boot.kernel.sysctl."net.ipv4.conf.default.log_martians" = mkDefault true;
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2019-08-11 12:32:24 +01:00
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boot.kernel.sysctl."net.ipv4.conf.default.rp_filter" = mkDefault "1";
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2019-07-04 17:51:06 +01:00
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# Ignore broadcast ICMP (mitigate SMURF)
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boot.kernel.sysctl."net.ipv4.icmp_echo_ignore_broadcasts" = mkDefault true;
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# Ignore incoming ICMP redirects (note: default is needed to ensure that the
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# setting is applied to interfaces added after the sysctls are set)
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boot.kernel.sysctl."net.ipv4.conf.all.accept_redirects" = mkDefault false;
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boot.kernel.sysctl."net.ipv4.conf.all.secure_redirects" = mkDefault false;
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boot.kernel.sysctl."net.ipv4.conf.default.accept_redirects" = mkDefault false;
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boot.kernel.sysctl."net.ipv4.conf.default.secure_redirects" = mkDefault false;
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boot.kernel.sysctl."net.ipv6.conf.all.accept_redirects" = mkDefault false;
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boot.kernel.sysctl."net.ipv6.conf.default.accept_redirects" = mkDefault false;
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# Ignore outgoing ICMP redirects (this is ipv4 only)
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boot.kernel.sysctl."net.ipv4.conf.all.send_redirects" = mkDefault false;
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boot.kernel.sysctl."net.ipv4.conf.default.send_redirects" = mkDefault false;
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2019-07-18 13:00:28 +01:00
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# Restrict userfaultfd syscalls to processes with the SYS_PTRACE capability
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boot.kernel.sysctl."vm.unprivileged_userfaultfd" = mkDefault false;
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2017-04-06 13:54:45 +01:00
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}
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