Julius Werner (jwerner@chromium.org) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/13949
-gerrit
commit 59e3046666f6b92b1ac8eddcf9db762d9c1220e7 Author: Julius Werner jwerner@chromium.org Date: Mon Mar 7 17:55:43 2016 -0800
Makefile: Build-time overlap check for programs loaded after coreboot
On non-x86 platforms, coreboot uses the memlayout.ld mechanism to statically allocate the different memory regions it needs and guarantees at build time that there are no dangerous overlaps between them. At the end of its (ramstage) execution, however, it usually loads a payload (and possibly other platform-specific components) that is not integrated into the coreboot build system and therefore cannot provide the same overlap guarantees through memlayout.ld. This creates a dangerous memory hazard where a new component could be loaded over memory areas that are still in use by the code-loading ramstage and lead to arbitrary memory corruption bugs.
This patch fills this gap in our build-time correctness guarantees by adding the necessary checks as a new intermediate Makefile target on route to assembling the final image. It will parse the memory footprint information of the payload (and other platform-specific post-ramstage components) from CBFS and compare it to a list of memory areas known to be still in use during late ramstage, generating a build failure in case of a possible hazard.
BUG=chrome-os-partner:48008 TEST=Built Oak while moving critical regions in the way of BL31 or the payload, observing the desired build-time errors. Built Nyan, Jerry and Falco without issues for good measure.
Change-Id: I3ebd2c1caa4df959421265e26f9cab2c54909b68 Signed-off-by: Julius Werner jwerner@chromium.org --- Makefile.inc | 46 +++++++++++++++++++++++++++++++++++++++++++++ src/arch/arm/Makefile.inc | 4 ++++ src/arch/arm64/Makefile.inc | 8 ++++++++ src/arch/mips/Makefile.inc | 4 ++++ src/arch/riscv/Makefile.inc | 4 ++++ 5 files changed, 66 insertions(+)
diff --git a/Makefile.inc b/Makefile.inc index 68012d9..d6a4d13 100644 --- a/Makefile.inc +++ b/Makefile.inc @@ -842,6 +842,52 @@ board_id-type := raw $(obj)/board_id: printf $(CONFIG_BOARD_ID_STRING) > $@
+# Ensure that no payload segment overlaps with memory regions used by ramstage +# (not for x86 since it can relocate itself in that case) +ifneq ($(CONFIG_ARCH_X86),y) +check-ramstage-overlap-regions := ramstage +check-ramstage-overlap-files := +ifneq ($(CONFIG_PAYLOAD_NONE),y) +check-ramstage-overlap-files += $(CONFIG_CBFS_PREFIX)/payload +endif + +# will output one or more lines of "<load address in hex> <memlen in decimal>" +cbfs-get-segments-cmd = $(CBFSTOOL) $(obj)/coreboot.pre print -v | sed -n \ + '%$(1)%,%^[^ ]{4}%s% .*load: (0x[0-9a-fA-F]*),.*length: [0-9]*/([0-9]*).*%\1 \2%p' + +ramstage-symbol-addr-cmd = $(OBJDUMP_ramstage) -t $(objcbfs)/ramstage.elf | \ + sed -n '/ $(1)$$/s/^([0-9a-fA-F]*) .*/0x\1/p' + +check-ramstage-overlaps: $(obj)/coreboot.pre + programs=$$($(foreach file,$(check-ramstage-overlap-files), \ + $(call cbfs-get-segments-cmd,$(file)) ; )) ; \ + regions=$$($(foreach region,$(check-ramstage-overlap-regions), \ + echo $(region) ; \ + $(call ramstage-symbol-addr-cmd,_$(region)) ; \ + $(call ramstage-symbol-addr-cmd,_e$(region)) ; )) ; \ + pstart= ; pend= ; \ + for x in $$programs; do \ + if [ -z $$pstart ]; then pstart=$$(($$x)) ; continue ; fi ; \ + pend=$$(($$pstart + $$x)) ; \ + rname= ; rstart= ; rend= ; \ + for y in $$regions ; do \ + if [ -z $$rname ]; then rname=$$y ; continue ; fi ; \ + if [ -z $$rstart ]; then rstart=$$(($$y)) ; continue ; fi ; \ + rend=$$(($$y)) ; \ + if [ $$pstart -lt $$rend -a $$rstart -lt $$pend ]; then \ + echo "ERROR: Ramstage region _$$rname overlapped by:" \ + $(check-ramstage-overlap-files) ; \ + exit 1 ; \ + fi ; \ + rname= ; rstart= ; rend= ; \ + done ; \ + pstart= ; pend= ; \ + done + +INTERMEDIATE+=check-ramstage-overlaps +PHONY+=check-ramstage-overlaps +endif + junit.xml: echo "Building $(UTIL)" echo '<?xml version="1.0" encoding="utf-8"?><testsuite>' > $@.tmp diff --git a/src/arch/arm/Makefile.inc b/src/arch/arm/Makefile.inc index b04a3db..d9c88c0 100644 --- a/src/arch/arm/Makefile.inc +++ b/src/arch/arm/Makefile.inc @@ -25,6 +25,10 @@ ifeq ($(CONFIG_ARCH_ROMSTAGE_ARM),y) CBFSTOOL_PRE1_OPTS = -m arm -s $(CONFIG_CBFS_SIZE) endif
+ifeq ($(CONFIG_ARCH_RAMSTAGE_ARM),y) +check-ramstage-overlap-regions += postram_cbfs_cache stack ttb +endif + ifeq ($(CONFIG_ARCH_ARM),y) subdirs-y += libgcc/ subdirs-y += armv4/ armv7/ diff --git a/src/arch/arm64/Makefile.inc b/src/arch/arm64/Makefile.inc index f44ee51..dffdd9c 100644 --- a/src/arch/arm64/Makefile.inc +++ b/src/arch/arm64/Makefile.inc @@ -33,6 +33,10 @@ ifeq ($(CONFIG_ARCH_ROMSTAGE_ARM64),y) CBFSTOOL_PRE1_OPTS = -m arm64 -s $(CONFIG_CBFS_SIZE) endif
+ifeq ($(CONFIG_ARCH_RAMSTAGE_ARM64),y) +check-ramstage-overlap-regions += postram_cbfs_cache stack ttb +endif + ################################################################################ # bootblock ################################################################################ @@ -182,6 +186,8 @@ $(BL31_CBFS)-type := stage $(BL31_CBFS)-compression := $(CBFS_COMPRESS_FLAG) cbfs-files-y += $(BL31_CBFS)
+check-ramstage-overlap-files += $(BL31_CBFS) + ifeq ($(CONFIG_ARM64_USE_SECURE_OS),y)
SECURE_OS_FILE := $(CONFIG_ARM64_SECURE_OS_FILE) @@ -190,6 +196,8 @@ $(SECURE_OS_FILE_CBFS)-file := $(SECURE_OS_FILE) $(SECURE_OS_FILE_CBFS)-type := stage cbfs-files-y += $(SECURE_OS_FILE_CBFS)
+check-ramstage-overlap-files += $(SECURE_OS_FILE_CBFS) + endif # CONFIG_ARM64_USE_SECURE_OS
endif # CONFIG_ARM64_USE_ARM_TRUSTED_FIRMWARE diff --git a/src/arch/mips/Makefile.inc b/src/arch/mips/Makefile.inc index a037525..0901388 100644 --- a/src/arch/mips/Makefile.inc +++ b/src/arch/mips/Makefile.inc @@ -22,6 +22,10 @@ ifeq ($(CONFIG_ARCH_ROMSTAGE_MIPS),y) CBFSTOOL_PRE1_OPTS = -m mips -s $(CONFIG_CBFS_SIZE) endif
+ifeq ($(CONFIG_ARCH_RAMSTAGE_MIPS),y) +check-ramstage-overlap-regions += stack +endif + ############################################################################### # bootblock ############################################################################### diff --git a/src/arch/riscv/Makefile.inc b/src/arch/riscv/Makefile.inc index 2d4d7e6..4abaf58 100644 --- a/src/arch/riscv/Makefile.inc +++ b/src/arch/riscv/Makefile.inc @@ -19,6 +19,10 @@ riscv_flags = -I$(src)/arch/riscv/
riscv_asm_flags =
+ifeq ($(CONFIG_ARCH_RAMSTAGE_RISCV),y) +check-ramstage-overlap-regions += stack +endif + ################################################################################ ## bootblock ################################################################################