658ab4b45b
this splits hardeningCFlags into hardeningCFlagsAfter and hardeningCFlagsBefore (where most flags still remain) to allow us to *append* `-D_FORTIFY_SOURCE=` values to the command-line, forcing our choice of fortify level and avoiding potential redefinition warnings/errors through use of `-U_FORTIFY_SOURCE`
111 lines
4.1 KiB
Bash
111 lines
4.1 KiB
Bash
declare -a hardeningCFlagsAfter=()
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declare -a hardeningCFlagsBefore=()
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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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hardeningCFlagsBefore+=('-O2' '-U_FORTIFY_SOURCE')
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# Unset any _FORTIFY_SOURCE values the command-line may have set before
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# enforcing our own value, avoiding (potentially fatal) redefinition
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# warnings
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hardeningCFlagsAfter+=('-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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hardeningCFlagsAfter+=('-D_FORTIFY_SOURCE=2')
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;;
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fortify3)
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if (( "${NIX_DEBUG:-0}" >= 1 )); then echo HARDENING: enabling fortify3 >&2; fi
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hardeningCFlagsAfter+=('-D_FORTIFY_SOURCE=3')
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;;
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*)
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# Ignore unsupported.
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;;
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esac
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;;
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stackprotector)
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if (( "${NIX_DEBUG:-0}" >= 1 )); then echo HARDENING: enabling stackprotector >&2; fi
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hardeningCFlagsBefore+=('-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 (( "${NIX_DEBUG:-0}" >= 1 )); then echo HARDENING: enabling CFlags -fPIE >&2; fi
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hardeningCFlagsBefore=('-fPIE' "${hardeningCFlagsBefore[@]}")
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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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hardeningCFlagsBefore=('-pie' "${hardeningCFlagsBefore[@]}")
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fi
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;;
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pic)
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if (( "${NIX_DEBUG:-0}" >= 1 )); then echo HARDENING: enabling pic >&2; fi
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hardeningCFlagsBefore+=('-fPIC')
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;;
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strictoverflow)
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if (( "${NIX_DEBUG:-0}" >= 1 )); then echo HARDENING: enabling strictoverflow >&2; fi
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if (( @isClang@ )); then
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# In Clang, -fno-strict-overflow only serves to set -fwrapv and is
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# reported as an unused CLI argument if -fwrapv or -fno-wrapv is set
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# explicitly, so we side step that by doing the conversion here.
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#
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# See: https://github.com/llvm/llvm-project/blob/llvmorg-16.0.6/clang/lib/Driver/ToolChains/Clang.cpp#L6315
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#
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hardeningCFlagsBefore+=('-fwrapv')
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else
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hardeningCFlagsBefore+=('-fno-strict-overflow')
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fi
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;;
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format)
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if (( "${NIX_DEBUG:-0}" >= 1 )); then echo HARDENING: enabling format >&2; fi
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hardeningCFlagsBefore+=('-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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