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From:   Evgeniy Baskov <baskov@ispras.ru>
To:     Ard Biesheuvel <ardb@kernel.org>
Cc:     Evgeniy Baskov <baskov@ispras.ru>, Borislav Petkov <bp@alien8.de>,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Alexey Khoroshilov <khoroshilov@ispras.ru>,
        Peter Jones <pjones@redhat.com>, lvc-project@linuxtesting.org,
        x86@kernel.org, linux-efi@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: [PATCH v2 07/23] x86/build: Check W^X of vmlinux during build
Date:   Tue, 25 Oct 2022 17:12:45 +0300
Message-Id: <84186fd75772b89be1984d6da0764a65cdef0c29.1666705333.git.baskov@ispras.ru>
In-Reply-To: <cover.1666705333.git.baskov@ispras.ru>
References: <cover.1666705333.git.baskov@ispras.ru>
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Check if there are simultaneously writable and executable
program segments in vmlinux ELF image and fail build if there are any.

This would prevent accidental introduction of RWX segments.

Signed-off-by: Evgeniy Baskov <baskov@ispras.ru>
---
 arch/x86/boot/compressed/Makefile | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 3a261abb6d15..64de6c2b1740 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -112,11 +112,17 @@ vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_thunk_$(BITS).o
 vmlinux-objs-$(CONFIG_EFI) += $(obj)/efi.o
 efi-obj-$(CONFIG_EFI_STUB) = $(objtree)/drivers/firmware/efi/libstub/lib.a
 
+quiet_cmd_wx_check = WXCHK   $<
+cmd_wx_check = if $(OBJDUMP) -p $< | grep "flags .wx" > /dev/null; \
+	       then (echo >&2 "$<: Simultaneously writable and executable sections are prohibited"; \
+		     /bin/false); fi
+
 $(obj)/vmlinux: $(vmlinux-objs-y) $(efi-obj-y) FORCE
 	$(call if_changed,ld)
 
 OBJCOPYFLAGS_vmlinux.bin :=  -R .comment -S
 $(obj)/vmlinux.bin: vmlinux FORCE
+	$(call cmd,wx_check)
 	$(call if_changed,objcopy)
 
 targets += $(patsubst $(obj)/%,%,$(vmlinux-objs-y)) vmlinux.bin.all vmlinux.relocs
-- 
2.37.4