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Message-ID: <20160128000906.GA42530@davidb.org>
Date: Wed, 27 Jan 2016 17:09:06 -0700
From: David Brown <david.brown@...aro.org>
To: Kees Cook <keescook@...omium.org>
Cc: "kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>,
Ingo Molnar <mingo@...hat.com>,
Andy Lutomirski <luto@...capital.net>,
"H. Peter Anvin" <hpa@...or.com>,
Michael Ellerman <mpe@...erman.id.au>,
Mathias Krause <minipli@...glemail.com>,
Thomas Gleixner <tglx@...utronix.de>,
"x86@...nel.org" <x86@...nel.org>, Arnd Bergmann <arnd@...db.de>,
PaX Team <pageexec@...email.hu>, Emese Revfy <re.emese@...il.com>,
LKML <linux-kernel@...r.kernel.org>,
linux-arch <linux-arch@...r.kernel.org>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
Marc Zyngier <marc.zyngier@....com>,
yalin wang <yalin.wang2010@...il.com>,
Zi Shen Lim <zlim.lnx@...il.com>, Yang Shi <yang.shi@...aro.org>,
Mark Rutland <mark.rutland@....com>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>,
Laura Abbott <lauraa@...eaurora.org>,
"Suzuki K. Poulose" <suzuki.poulose@....com>,
Steve Capper <steve.capper@...aro.org>,
Jeremy Linton <jeremy.linton@....com>,
Mark Salter <msalter@...hat.com>,
linux-arm-kernel@...ts.infradead.org
Subject: [PATCH] arm64: make CONFIG_DEBUG_RODATA non-optional
>From 2efef8aa0f8f7f6277ffebe4ea6744fc93d54644 Mon Sep 17 00:00:00 2001
From: David Brown <david.brown@...aro.org>
Date: Wed, 27 Jan 2016 13:58:44 -0800
This removes the CONFIG_DEBUG_RODATA option and makes it always
enabled.
Signed-off-by: David Brown <david.brown@...aro.org>
---
v1: This is in the same spirit as the x86 patch, removing allowing
this option to be config selected. The associated patch series adds a
runtime option for the same thing. However, it does affect the way
some things are mapped, and could possibly result in either increased
memory usage, or a performance hit (due to TLB misses from 4K pages).
I've tested this on a Hikey 96board (hi6220-hikey.dtb), both with and
without 'rodata=off' on the command line.
arch/arm64/Kconfig | 3 +++
arch/arm64/Kconfig.debug | 10 ----------
arch/arm64/kernel/insn.c | 2 +-
arch/arm64/kernel/vmlinux.lds.S | 5 +----
arch/arm64/mm/mmu.c | 12 ------------
5 files changed, 5 insertions(+), 27 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 8cc6228..ffa617a 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -201,6 +201,9 @@ config KERNEL_MODE_NEON
config FIX_EARLYCON_MEM
def_bool y
+config DEBUG_RODATA
+ def_bool y
+
config PGTABLE_LEVELS
int
default 2 if ARM64_16K_PAGES && ARM64_VA_BITS_36
diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug
index e13c4bf..db994ec 100644
--- a/arch/arm64/Kconfig.debug
+++ b/arch/arm64/Kconfig.debug
@@ -48,16 +48,6 @@ config DEBUG_SET_MODULE_RONX
against certain classes of kernel exploits.
If in doubt, say "N".
-config DEBUG_RODATA
- bool "Make kernel text and rodata read-only"
- help
- If this is set, kernel text and rodata will be made read-only. This
- is to help catch accidental or malicious attempts to change the
- kernel's executable code. Additionally splits rodata from kernel
- text so it can be made explicitly non-executable.
-
- If in doubt, say Y
-
config DEBUG_ALIGN_RODATA
depends on DEBUG_RODATA && ARM64_4K_PAGES
bool "Align linker sections up to SECTION_SIZE"
diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c
index 7371455..a04bdef 100644
--- a/arch/arm64/kernel/insn.c
+++ b/arch/arm64/kernel/insn.c
@@ -95,7 +95,7 @@ static void __kprobes *patch_map(void *addr, int fixmap)
if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
page = vmalloc_to_page(addr);
- else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
+ else if (!module)
page = virt_to_page(addr);
else
return addr;
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index e3928f5..f80903c 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -65,12 +65,9 @@ PECOFF_FILE_ALIGNMENT = 0x200;
#if defined(CONFIG_DEBUG_ALIGN_RODATA)
#define ALIGN_DEBUG_RO . = ALIGN(1<<SECTION_SHIFT);
#define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO
-#elif defined(CONFIG_DEBUG_RODATA)
+#else
#define ALIGN_DEBUG_RO . = ALIGN(1<<PAGE_SHIFT);
#define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO
-#else
-#define ALIGN_DEBUG_RO
-#define ALIGN_DEBUG_RO_MIN(min) . = ALIGN(min);
#endif
SECTIONS
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 58faeaa..3b411b7 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -313,7 +313,6 @@ static void create_mapping_late(phys_addr_t phys, unsigned long virt,
phys, virt, size, prot, late_alloc);
}
-#ifdef CONFIG_DEBUG_RODATA
static void __init __map_memblock(phys_addr_t start, phys_addr_t end)
{
/*
@@ -347,13 +346,6 @@ static void __init __map_memblock(phys_addr_t start, phys_addr_t end)
}
}
-#else
-static void __init __map_memblock(phys_addr_t start, phys_addr_t end)
-{
- create_mapping(start, __phys_to_virt(start), end - start,
- PAGE_KERNEL_EXEC);
-}
-#endif
static void __init map_mem(void)
{
@@ -410,7 +402,6 @@ static void __init map_mem(void)
static void __init fixup_executable(void)
{
-#ifdef CONFIG_DEBUG_RODATA
/* now that we are actually fully mapped, make the start/end more fine grained */
if (!IS_ALIGNED((unsigned long)_stext, SWAPPER_BLOCK_SIZE)) {
unsigned long aligned_start = round_down(__pa(_stext),
@@ -428,10 +419,8 @@ static void __init fixup_executable(void)
aligned_end - __pa(__init_end),
PAGE_KERNEL);
}
-#endif
}
-#ifdef CONFIG_DEBUG_RODATA
void mark_rodata_ro(void)
{
create_mapping_late(__pa(_stext), (unsigned long)_stext,
@@ -439,7 +428,6 @@ void mark_rodata_ro(void)
PAGE_KERNEL_ROX);
}
-#endif
void fixup_init(void)
{
--
2.7.0
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