On Wed, Jul 15, 2020 at 2:41 AM Arvind Sankar <[email protected]> wrote: > > Add a linker script check that there are no run-time relocations, and > remove the old one that tries to check via looking for specially-named > sections in the object files. > > Drop the tests for -fPIE compiler option and -pie linker option, as they > are available in all supported gcc and binutils versions (as well as > clang and lld). >
Tested-by: Sedat Dilek <[email protected]> Reported-by: Sedat Dilek <[email protected]> Here I reported the breakage with LLD and tested the move to LDFLAGS_vmlinux with a previous version of the patch. - Sedat - > Reviewed-by: Kees Cook <[email protected]> > Reviewed-by: Ard Biesheuvel <[email protected]> > Reviewed-by: Fangrui Song <[email protected]> > Signed-off-by: Arvind Sankar <[email protected]> > --- > arch/x86/boot/compressed/Makefile | 28 +++----------------------- > arch/x86/boot/compressed/vmlinux.lds.S | 8 ++++++++ > 2 files changed, 11 insertions(+), 25 deletions(-) > > diff --git a/arch/x86/boot/compressed/Makefile > b/arch/x86/boot/compressed/Makefile > index ae2c0dc98a6a..a9e082b8c720 100644 > --- a/arch/x86/boot/compressed/Makefile > +++ b/arch/x86/boot/compressed/Makefile > @@ -29,7 +29,7 @@ targets := vmlinux vmlinux.bin vmlinux.bin.gz > vmlinux.bin.bz2 vmlinux.bin.lzma \ > vmlinux.bin.xz vmlinux.bin.lzo vmlinux.bin.lz4 > > KBUILD_CFLAGS := -m$(BITS) -O2 > -KBUILD_CFLAGS += -fno-strict-aliasing $(call cc-option, -fPIE, -fPIC) > +KBUILD_CFLAGS += -fno-strict-aliasing -fPIE > KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING > cflags-$(CONFIG_X86_32) := -march=i386 > cflags-$(CONFIG_X86_64) := -mcmodel=small > @@ -51,7 +51,7 @@ UBSAN_SANITIZE :=n > KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE) > # Compressed kernel should be built as PIE since it may be loaded at any > # address by the bootloader. > -LDFLAGS_vmlinux := $(call ld-option, -pie) $(call ld-option, > --no-dynamic-linker) > +LDFLAGS_vmlinux := -pie $(call ld-option, --no-dynamic-linker) > LDFLAGS_vmlinux += -T > > hostprogs := mkpiggy > @@ -86,30 +86,8 @@ vmlinux-objs-$(CONFIG_ACPI) += $(obj)/acpi.o > vmlinux-objs-$(CONFIG_EFI_STUB) += > $(objtree)/drivers/firmware/efi/libstub/lib.a > vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_thunk_$(BITS).o > > -# The compressed kernel is built with -fPIC/-fPIE so that a boot loader > -# can place it anywhere in memory and it will still run. However, since > -# it is executed as-is without any ELF relocation processing performed > -# (and has already had all relocation sections stripped from the binary), > -# none of the code can use data relocations (e.g. static assignments of > -# pointer values), since they will be meaningless at runtime. This check > -# will refuse to link the vmlinux if any of these relocations are found. > -quiet_cmd_check_data_rel = DATAREL $@ > -define cmd_check_data_rel > - for obj in $(filter %.o,$^); do \ > - $(READELF) -S $$obj | grep -qF .rel.local && { \ > - echo "error: $$obj has data relocations!" >&2; \ > - exit 1; \ > - } || true; \ > - done > -endef > - > -# We need to run two commands under "if_changed", so merge them into a > -# single invocation. > -quiet_cmd_check-and-link-vmlinux = LD $@ > - cmd_check-and-link-vmlinux = $(cmd_check_data_rel); $(cmd_ld) > - > $(obj)/vmlinux: $(vmlinux-objs-y) FORCE > - $(call if_changed,check-and-link-vmlinux) > + $(call if_changed,ld) > > OBJCOPYFLAGS_vmlinux.bin := -R .comment -S > $(obj)/vmlinux.bin: vmlinux FORCE > diff --git a/arch/x86/boot/compressed/vmlinux.lds.S > b/arch/x86/boot/compressed/vmlinux.lds.S > index a4a4a59a2628..29df99b6cc64 100644 > --- a/arch/x86/boot/compressed/vmlinux.lds.S > +++ b/arch/x86/boot/compressed/vmlinux.lds.S > @@ -42,6 +42,12 @@ SECTIONS > *(.rodata.*) > _erodata = . ; > } > + .rel.dyn : { > + *(.rel.*) > + } > + .rela.dyn : { > + *(.rela.*) > + } > .got : { > *(.got) > } > @@ -85,3 +91,5 @@ ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0x18, > "Unexpected GOT/PLT en > #else > ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0xc, "Unexpected GOT/PLT > entries detected!") > #endif > + > +ASSERT(SIZEOF(.rel.dyn) == 0 && SIZEOF(.rela.dyn) == 0, "Unexpected run-time > relocations detected!") > -- > 2.26.2 >
