linux-kernel - [PATCH v3 5/9] x86/boot: Warn on orphan section placement

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20200624014940.1204448-6-keescook@chromium.org>
Date:   Tue, 23 Jun 2020 18:49:36 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Will Deacon <will@...nel.org>
Cc:     Kees Cook <keescook@...omium.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Mark Rutland <mark.rutland@....com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Peter Collingbourne <pcc@...gle.com>,
        James Morse <james.morse@....com>,
        Borislav Petkov <bp@...e.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Russell King <linux@...linux.org.uk>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Arnd Bergmann <arnd@...db.de>, x86@...nel.org,
        clang-built-linux@...glegroups.com, linux-arch@...r.kernel.org,
        linux-efi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 5/9] x86/boot: Warn on orphan section placement

We don't want to depend on the linker's orphan section placement
heuristics as these can vary between linkers, and may change between
versions. All sections need to be explicitly named in the linker
script.

Add the common debugging sections. Discard the unused note, rel, plt,
dyn, and hash sections that are not needed in the compressed vmlinux.
Disable .eh_frame generation in the linker and enable orphan section
warnings.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 arch/x86/boot/compressed/Makefile      |  3 ++-
 arch/x86/boot/compressed/vmlinux.lds.S | 11 +++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 7619742f91c9..646720a05f89 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -48,6 +48,7 @@ GCOV_PROFILE := n
 UBSAN_SANITIZE :=n
 
 KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE)
+KBUILD_LDFLAGS += $(call ld-option,--no-ld-generated-unwind-info)
 # Compressed kernel should be built as PIE since it may be loaded at any
 # address by the bootloader.
 ifeq ($(CONFIG_X86_32),y)
@@ -59,7 +60,7 @@ else
 KBUILD_LDFLAGS += $(shell $(LD) --help 2>&1 | grep -q "\-z noreloc-overflow" \
 	&& echo "-z noreloc-overflow -pie --no-dynamic-linker")
 endif
-LDFLAGS_vmlinux := -T
+LDFLAGS_vmlinux := --orphan-handling=warn -T
 
 hostprogs	:= mkpiggy
 HOST_EXTRACFLAGS += -I$(srctree)/tools/include
diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S
index 8f1025d1f681..6fe3ecdfd685 100644
--- a/arch/x86/boot/compressed/vmlinux.lds.S
+++ b/arch/x86/boot/compressed/vmlinux.lds.S
@@ -75,5 +75,16 @@ SECTIONS
 	. = ALIGN(PAGE_SIZE);	/* keep ZO size page aligned */
 	_end = .;
 
+	STABS_DEBUG
+	DWARF_DEBUG
+
 	DISCARDS
+	/DISCARD/ : {
+		*(.note.*)
+		*(.rela.*) *(.rela_*)
+		*(.rel.*) *(.rel_*)
+		*(.plt) *(.plt.*)
+		*(.dyn*)
+		*(.hash) *(.gnu.hash)
+	}
 }
-- 
2.25.1