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![Kees Cook](/assets/img/avatar_default.png)
While the run-time testing of FORTIFY_SOURCE is already present in LKDTM, there is no testing of the expected compile-time detections. In preparation for correctly supporting FORTIFY_SOURCE under Clang, adding additional FORTIFY_SOURCE defenses, and making sure FORTIFY_SOURCE doesn't silently regress with GCC, introduce a build-time test suite that checks each expected compile-time failure condition. As this is relatively backwards from standard build rules in the sense that a successful test is actually a compile _failure_, create a wrapper script to check for the correct errors, and wire it up as a dummy dependency to lib/string.o, collecting the results into a log file artifact. Signed-off-by: Kees Cook <keescook@chromium.org>
62 lines
1.8 KiB
Bash
62 lines
1.8 KiB
Bash
#!/bin/sh
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# SPDX-License-Identifier: GPL-2.0-only
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set -e
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# Argument 1: Source file to build.
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IN="$1"
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shift
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# Extract just the filename for error messages below.
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FILE="${IN##*/}"
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# Extract the function name for error messages below.
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FUNC="${FILE#*-}"
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FUNC="${FUNC%%-*}"
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FUNC="${FUNC%%.*}"
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# Extract the symbol to test for in build/symbol test below.
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WANT="__${FILE%%-*}"
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# Argument 2: Where to write the build log.
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OUT="$1"
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shift
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TMP="${OUT}.tmp"
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# Argument 3: Path to "nm" tool.
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NM="$1"
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shift
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# Remaining arguments are: $(CC) $(c_flags)
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# Clean up temporary file at exit.
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__cleanup() {
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rm -f "$TMP"
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}
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trap __cleanup EXIT
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# Function names in warnings are wrapped in backticks under UTF-8 locales.
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# Run the commands with LANG=C so that grep output will not change.
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export LANG=C
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status=
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# Attempt to build a source that is expected to fail with a specific warning.
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if "$@" -Werror -c "$IN" -o "$OUT".o 2> "$TMP" ; then
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# If the build succeeds, either the test has failed or the
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# warning may only happen at link time (Clang). In that case,
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# make sure the expected symbol is unresolved in the symbol list.
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# If so, FORTIFY is working for this case.
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if ! $NM -A "$OUT".o | grep -m1 "\bU ${WANT}$" >>"$TMP" ; then
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status="warning: unsafe ${FUNC}() usage lacked '$WANT' symbol in $IN"
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fi
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else
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# If the build failed, check for the warning in the stderr (gcc).
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if ! grep -q -m1 "error: call to .\b${WANT}\b." "$TMP" ; then
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status="warning: unsafe ${FUNC}() usage lacked '$WANT' warning in $IN"
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fi
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fi
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if [ -n "$status" ]; then
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# Report on failure results, including compilation warnings.
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echo "$status" | tee "$OUT" >&2
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else
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# Report on good results, and save any compilation output to log.
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echo "ok: unsafe ${FUNC}() usage correctly detected with '$WANT' in $IN" >"$OUT"
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fi
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cat "$TMP" >>"$OUT"
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