On Wed, Jul 15, 2020 at 11:00 AM Sedat Dilek <[email protected]> wrote: > > 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. >
Feel free to also add my: Reviewed-by: Sedat Dilek <[email protected]> - 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 > >
