92 lines
		
	
	
		
			2.6 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
			
		
		
	
	
			92 lines
		
	
	
		
			2.6 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
{ config, lib, pkgs, ... }:
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with lib;
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let
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  cfg = config.environment.memoryAllocator;
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  # The set of alternative malloc(3) providers.
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  providers = {
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    graphene-hardened = {
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      libPath = "${pkgs.graphene-hardened-malloc}/lib/libhardened_malloc.so";
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      description = ''
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        An allocator designed to mitigate memory corruption attacks, such as
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        those caused by use-after-free bugs.
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      '';
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    };
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    jemalloc = {
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      libPath = "${pkgs.jemalloc}/lib/libjemalloc.so";
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      description = ''
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        A general purpose allocator that emphasizes fragmentation avoidance
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        and scalable concurrency support.
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      '';
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    };
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    scudo = {
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      libPath = "${pkgs.llvmPackages_latest.compiler-rt}/lib/linux/libclang_rt.scudo-x86_64.so";
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      description = ''
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        A user-mode allocator based on LLVM Sanitizer’s CombinedAllocator,
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        which aims at providing additional mitigations against heap based
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        vulnerabilities, while maintaining good performance.
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      '';
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    };
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  };
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  providerConf = providers.${cfg.provider};
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  # An output that contains only the shared library, to avoid
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  # needlessly bloating the system closure
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  mallocLib = pkgs.runCommand "malloc-provider-${cfg.provider}"
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    rec {
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      preferLocalBuild = true;
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      allowSubstitutes = false;
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      origLibPath = providerConf.libPath;
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      libName = baseNameOf origLibPath;
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    }
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    ''
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      mkdir -p $out/lib
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      cp -L $origLibPath $out/lib/$libName
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    '';
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  # The full path to the selected provider shlib.
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  providerLibPath = "${mallocLib}/lib/${mallocLib.libName}";
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in
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{
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  meta = {
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    maintainers = [ maintainers.joachifm ];
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  };
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  options = {
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    environment.memoryAllocator.provider = mkOption {
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      type = types.enum ([ "libc" ] ++ attrNames providers);
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      default = "libc";
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      description = ''
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        The system-wide memory allocator.
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        Briefly, the system-wide memory allocator providers are:
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        <itemizedlist>
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        <listitem><para><literal>libc</literal>: the standard allocator provided by libc</para></listitem>
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        ${toString (mapAttrsToList
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            (name: value: "<listitem><para><literal>${name}</literal>: ${value.description}</para></listitem>")
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            providers)}
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        </itemizedlist>
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        <warning>
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        <para>
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        Selecting an alternative allocator (i.e., anything other than
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        <literal>libc</literal>) may result in instability, data loss,
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        and/or service failure.
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        </para>
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        </warning>
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      '';
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    };
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  };
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  config = mkIf (cfg.provider != "libc") {
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    environment.etc."ld-nix.so.preload".text = ''
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      ${providerLibPath}
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    '';
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  };
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}
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