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Merge pull request #48439 from joachifm/hardened-misc

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nixos/security/misc: init
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Joachim F 2018-10-15 21:25:42 +00:00 committed by GitHub
parent a229408802 f4ea22e5de
commit 205aff5a65
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3 changed files with 42 additions and 12 deletions
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1
nixos/modules/module-list.nix
View file

@ -149,6 +149,7 @@
./security/duosec.nix
./security/hidepid.nix
./security/lock-kernel-modules.nix
./security/misc.nix
./security/oath.nix
./security/pam.nix
./security/pam_usb.nix

14
nixos/modules/profiles/hardened.nix
View file

@ -16,6 +16,8 @@ with lib;
security.lockKernelModules = mkDefault true;
security.allowUserNamespaces = mkDefault false;
security.apparmor.enable = mkDefault true;
boot.kernelParams = [
@ -59,18 +61,6 @@ with lib;
# ... or at least apply some hardening to it
boot.kernel.sysctl."net.core.bpf_jit_harden" = mkDefault true;
# A recurring problem with user namespaces is that there are
# still code paths where the kernel's permission checking logic
# fails to account for namespacing, instead permitting a
# namespaced process to act outside the namespace with the
# same privileges as it would have inside it. This is particularly
# bad in the common case of running as root within the namespace.
#
# Setting the number of allowed user namespaces to 0 effectively disables
# the feature at runtime. Attempting to create a user namespace
# with unshare will then fail with "no space left on device".
boot.kernel.sysctl."user.max_user_namespaces" = mkDefault 0;
# Raise ASLR entropy for 64bit & 32bit, respectively.
#
# Note: mmap_rnd_compat_bits may not exist on 64bit.

39
nixos/modules/security/misc.nix Normal file
View file

@ -0,0 +1,39 @@
{ config, lib, ... }:
with lib;
{
meta = {
maintainers = [ maintainers.joachifm ];
};
options = {
security.allowUserNamespaces = mkOption {
type = types.bool;
default = true;
description = ''
Whether to allow creation of user namespaces. A recurring problem
with user namespaces is the presence of code paths where the kernel's
permission checking logic fails to account for namespacing, instead
permitting a namespaced process to act outside the namespace with the
same privileges as it would have inside it. This is particularly
damaging in the common case of running as root within the namespace.
When user namespace creation is disallowed, attempting to create
a user namespace fails with "no space left on device" (ENOSPC).
'';
};
};
config = mkIf (!config.security.allowUserNamespaces) {
# Setting the number of allowed user namespaces to 0 effectively disables
# the feature at runtime. Note that root may raise the limit again
# at any time.
boot.kernel.sysctl."user.max_user_namespaces" = 0;
assertions = [
{ assertion = config.nix.useSandbox -> config.security.allowUserNamespaces;
message = "`nix.useSandbox = true` conflicts with `!security.allowUserNamespaces`.";
}
];
};
}