diff --git a/nixos/modules/config/malloc.nix b/nixos/modules/config/malloc.nix new file mode 100644 index 000000000000..7a42b0803be5 --- /dev/null +++ b/nixos/modules/config/malloc.nix @@ -0,0 +1,91 @@ +{ config, lib, pkgs, ... }: +with lib; + +let + cfg = config.environment.memoryAllocator; + + # The set of alternative malloc(3) providers. + providers = { + "graphene-hardened" = rec { + libPath = "${pkgs.graphene-hardened-malloc}/lib/libhardened_malloc.so"; + description = '' + An allocator designed to mitigate memory corruption attacks, such as + those caused by use-after-free bugs. + ''; + }; + + "jemalloc" = { + libPath = "${pkgs.jemalloc}/lib/libjemalloc.so"; + description = '' + A general purpose allocator that emphasizes fragmentation avoidance + and scalable concurrency support. + ''; + }; + }; + + providerConf = providers."${cfg.provider}"; + + # An output that contains only the shared library, to avoid + # needlessly bloating the system closure + mallocLib = pkgs.runCommand "malloc-provider-${cfg.provider}" + rec { + preferLocalBuild = true; + allowSubstitutes = false; + origLibPath = providerConf.libPath; + libName = baseNameOf origLibPath; + } + '' + mkdir -p $out/lib + cp -L $origLibPath $out/lib/$libName + ''; + + # The full path to the selected provider shlib. + providerLibPath = "${mallocLib}/lib/${mallocLib.libName}"; +in + +{ + meta = { + maintainers = [ maintainers.joachifm ]; + }; + + options = { + environment.memoryAllocator.provider = mkOption { + type = types.enum ([ "libc" ] ++ attrNames providers); + default = "libc"; + description = '' + The system-wide memory allocator. + + + + Briefly, the system-wide memory allocator providers are: + + libc: the standard allocator provided by libc + ${toString (mapAttrsToList + (name: value: "${name}: ${value.description}") + providers)} + + + + + + Selecting an alternative allocator (i.e., anything other than + libc) may result in instability, data loss, + and/or service failure. + + + + + + Changing this option does not affect the current session. + + + + + ''; + }; + }; + + config = mkIf (cfg.provider != "libc") { + environment.variables.LD_PRELOAD = providerLibPath; + }; +} diff --git a/nixos/modules/module-list.nix b/nixos/modules/module-list.nix index dee850f47f27..a66747f03844 100644 --- a/nixos/modules/module-list.nix +++ b/nixos/modules/module-list.nix @@ -19,6 +19,7 @@ ./config/iproute2.nix ./config/krb5/default.nix ./config/ldap.nix + ./config/malloc.nix ./config/networking.nix ./config/no-x-libs.nix ./config/nsswitch.nix diff --git a/nixos/modules/profiles/hardened.nix b/nixos/modules/profiles/hardened.nix index 9ab2ee87a19e..87bf66333c61 100644 --- a/nixos/modules/profiles/hardened.nix +++ b/nixos/modules/profiles/hardened.nix @@ -14,6 +14,8 @@ with lib; nix.allowedUsers = mkDefault [ "@users" ]; + environment.memoryAllocator.provider = mkDefault "graphene-hardened"; + security.hideProcessInformation = mkDefault true; security.lockKernelModules = mkDefault true; diff --git a/nixos/tests/hardened.nix b/nixos/tests/hardened.nix index 614889c4d73c..1ff329bd98de 100644 --- a/nixos/tests/hardened.nix +++ b/nixos/tests/hardened.nix @@ -27,6 +27,20 @@ import ./make-test.nix ({ pkgs, ...} : { }; testScript = + let + hardened-malloc-tests = pkgs.stdenv.mkDerivation rec { + name = "hardened-malloc-tests-${pkgs.graphene-hardened-malloc.version}"; + src = pkgs.graphene-hardened-malloc.src; + buildPhase = '' + cd test/simple-memory-corruption + make -j4 + ''; + + installPhase = '' + find . -type f -executable -exec install -Dt $out/bin '{}' + + ''; + }; + in '' $machine->waitForUnit("multi-user.target"); @@ -93,5 +107,18 @@ import ./make-test.nix ({ pkgs, ...} : { $machine->fail("systemctl hibernate"); $machine->fail("systemctl kexec"); }; + + # Test hardened memory allocator + sub runMallocTestProg { + my ($progName, $errorText) = @_; + my $text = "fatal allocator error: " . $errorText; + $machine->fail("${hardened-malloc-tests}/bin/" . $progName) =~ $text; + }; + + subtest "hardenedmalloc", sub { + runMallocTestProg("double_free_large", "invalid free"); + runMallocTestProg("unaligned_free_small", "invalid unaligned free"); + runMallocTestProg("write_after_free_small", "detected write after free"); + }; ''; })