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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id w205sm6244774pfc.75.2020.03.20.11.24.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Mar 2020 11:24:23 -0700 (PDT) Date: Fri, 20 Mar 2020 11:24:22 -0700 From: Kees Cook To: Nicholas Piggin Cc: Borislav Petkov , Arnd Bergmann , Catalin Marinas , clang-built-linux@googlegroups.com, "H.J. Lu" , James Morse , linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Russell King , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, Mark Rutland , Masahiro Yamada , Peter Collingbourne , Will Deacon , x86@kernel.org Subject: Re: [PATCH 1/9] scripts/link-vmlinux.sh: Delay orphan handling warnings until final link Message-ID: <202003201121.8CBD96451B@keescook> References: <20200228002244.15240-1-keescook@chromium.org> <20200228002244.15240-2-keescook@chromium.org> <1584672297.mudnpz3ir9.astroid@bobo.none> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1584672297.mudnpz3ir9.astroid@bobo.none> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 20, 2020 at 12:47:54PM +1000, Nicholas Piggin wrote: > Kees Cook's on February 28, 2020 10:22 am: > > Right now, powerpc adds "--orphan-handling=warn" to LD_FLAGS_vmlinux > > to detect when there are unexpected sections getting added to the kernel > > image. There is no need to report these warnings more than once, so it > > can be removed until the final link stage. > > > > This helps pave the way for other architectures to enable this, with the > > end goal of enabling this warning by default for vmlinux for all > > architectures. > > > > Signed-off-by: Kees Cook > > --- > > scripts/link-vmlinux.sh | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > > index 1919c311c149..416968fea685 100755 > > --- a/scripts/link-vmlinux.sh > > +++ b/scripts/link-vmlinux.sh > > @@ -255,6 +255,11 @@ info GEN modules.builtin > > tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' | > > tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin > > > > + > > +# Do not warn about orphan sections until the final link stage. > > +saved_LDFLAGS_vmlinux="${LDFLAGS_vmlinux}" > > +LDFLAGS_vmlinux="$(echo "${LDFLAGS_vmlinux}" | sed -E 's/ --orphan-handling=warn( |$)/ /g')" > > + > > btf_vmlinux_bin_o="" > > if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then > > if gen_btf .tmp_vmlinux.btf .btf.vmlinux.bin.o ; then > > @@ -306,6 +311,7 @@ if [ -n "${CONFIG_KALLSYMS}" ]; then > > fi > > fi > > > > +LDFLAGS_vmlinux="${saved_LDFLAGS_vmlinux}" > > vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} > > > > if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then > > That's ugly. Why not just enable it for all archs? It is ugly; I agree. I can try to do this for all architectures, but I worry there are a bunch I can't test. But I guess it would stand out. ;) -Kees -- Kees Cook