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e0d2053b87
When a response file is in use, "$*" contains the response file and not
the parameters; both the linker and compiler wrappers are updated to use
the response-expanded params.
The compiler driver likes to pass parameters to the linker via a
response file, including -shared.
LLD rejects the combination of (-shared -pie), whereas other linkers
silently ignore the contradiction:
```
ld.lld: error: -shared and -pie may not be used together
```
This breaks certain configurations using LLD as a linker.
Changing `add-hardening.sh` results in a full rebuild. To avoid the
rebuild, here is a quick test case which shows the new hardening script
allows the link to succeed:
```
{ pkgs ? import <nixpkgs> {} }:
let
# gcc silently accepts -shared -pie together, lld does not.
linker = pkgs.wrapBintoolsWith { bintools = pkgs.llvmPackages.lld; };
patchWrapper = prev: prev.overrideAttrs (final: prev: let
prevScript = builtins.match (".*(/nix/store/[a-z0-9]+-add-hardening.sh).*") prev.postFixup;
in {
postFixup = (builtins.replaceStrings prevScript ["${./new-add-hardening.sh}"] prev.postFixup);
});
in
pkgs.stdenv.mkDerivation {
name = "nixpkgs-hardening-bug";
src = pkgs.writeText "src.c" "int main(int argc, char* argv[]) { return 0; }";
NIX_HARDENING_ENABLE = "pie";
unpackPhase = ":";
buildPhase = ''
$CC -c -o src.o $src
bash -x ${patchWrapper linker}/bin/ld.lld -o $out @${pkgs.writeText "responsefile" "-shared"} src.o
'';
}
```
Fixes: #178162
Signed-off-by: Peter Waller <p@pwaller.net>
97 lines
3.4 KiB
Bash
97 lines
3.4 KiB
Bash
declare -a hardeningCFlags=()
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declare -A hardeningEnableMap=()
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# Intentionally word-split in case 'NIX_HARDENING_ENABLE' is defined in Nix. The
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# array expansion also prevents undefined variables from causing trouble with
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# `set -u`.
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for flag in ${NIX_HARDENING_ENABLE_@suffixSalt@-}; do
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hardeningEnableMap["$flag"]=1
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done
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# Remove unsupported flags.
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for flag in @hardening_unsupported_flags@; do
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unset -v "hardeningEnableMap[$flag]"
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# fortify being unsupported implies fortify3 is unsupported
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if [[ "$flag" = 'fortify' ]] ; then
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unset -v "hardeningEnableMap['fortify3']"
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fi
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done
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# make fortify and fortify3 mutually exclusive
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if [[ -n "${hardeningEnableMap[fortify3]-}" ]]; then
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unset -v "hardeningEnableMap['fortify']"
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fi
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if (( "${NIX_DEBUG:-0}" >= 1 )); then
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declare -a allHardeningFlags=(fortify stackprotector pie pic strictoverflow format)
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declare -A hardeningDisableMap=()
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# Determine which flags were effectively disabled so we can report below.
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for flag in "${allHardeningFlags[@]}"; do
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if [[ -z "${hardeningEnableMap[$flag]-}" ]]; then
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hardeningDisableMap["$flag"]=1
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fi
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done
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printf 'HARDENING: disabled flags:' >&2
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(( "${#hardeningDisableMap[@]}" )) && printf ' %q' "${!hardeningDisableMap[@]}" >&2
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echo >&2
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if (( "${#hardeningEnableMap[@]}" )); then
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echo 'HARDENING: Is active (not completely disabled with "all" flag)' >&2;
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fi
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fi
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for flag in "${!hardeningEnableMap[@]}"; do
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case $flag in
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fortify | fortify3)
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# Use -U_FORTIFY_SOURCE to avoid warnings on toolchains that explicitly
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# set -D_FORTIFY_SOURCE=0 (like 'clang -fsanitize=address').
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hardeningCFlags+=('-O2' '-U_FORTIFY_SOURCE')
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case $flag in
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fortify)
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if (( "${NIX_DEBUG:-0}" >= 1 )); then echo HARDENING: enabling fortify >&2; fi
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hardeningCFlags+=('-D_FORTIFY_SOURCE=2')
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;;
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fortify3)
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if (( "${NIX_DEBUG:-0}" >= 1 )); then echo HARDENING: enabling fortify3 >&2; fi
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hardeningCFlags+=('-D_FORTIFY_SOURCE=3')
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;;
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*)
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# Ignore unsupported.
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;;
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esac
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;;
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stackprotector)
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if (( "${NIX_DEBUG:-0}" >= 1 )); then echo HARDENING: enabling stackprotector >&2; fi
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hardeningCFlags+=('-fstack-protector-strong' '--param' 'ssp-buffer-size=4')
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;;
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pie)
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# NB: we do not use `+=` here, because PIE flags must occur before any PIC flags
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if (( "${NIX_DEBUG:-0}" >= 1 )); then echo HARDENING: enabling CFlags -fPIE >&2; fi
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hardeningCFlags=('-fPIE' "${hardeningCFlags[@]}")
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if [[ ! (" ${params[*]} " =~ " -shared " || " ${params[*]} " =~ " -static ") ]]; then
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if (( "${NIX_DEBUG:-0}" >= 1 )); then echo HARDENING: enabling LDFlags -pie >&2; fi
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hardeningCFlags=('-pie' "${hardeningCFlags[@]}")
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fi
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;;
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pic)
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if (( "${NIX_DEBUG:-0}" >= 1 )); then echo HARDENING: enabling pic >&2; fi
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hardeningCFlags+=('-fPIC')
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;;
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strictoverflow)
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if (( "${NIX_DEBUG:-0}" >= 1 )); then echo HARDENING: enabling strictoverflow >&2; fi
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hardeningCFlags+=('-fno-strict-overflow')
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;;
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format)
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if (( "${NIX_DEBUG:-0}" >= 1 )); then echo HARDENING: enabling format >&2; fi
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hardeningCFlags+=('-Wformat' '-Wformat-security' '-Werror=format-security')
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;;
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*)
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# Ignore unsupported. Checked in Nix that at least *some*
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# tool supports each flag.
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;;
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esac
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done
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