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Date: Wed, 20 Jun 2018 16:57:55 +0800
From: Jun Yao <yaojun8558363@...il.com>
To: linux-arm-kernel@...ts.infradead.org
Cc: catalin.marinas@....com,
will.deacon@....com,
ard.biesheuvel@...aro.org,
james.morse@....com,
linux-kernel@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: [PATCH 1/1] arm64/mm: move {idmap_pg_dir,tramp_pg_dir,swapper_pg_dir} to .rodata section
Move {idmap_pg_dir,tramp_pg_dir,swapper_pg_dir} to .rodata
section. And update the swapper_pg_dir by fixmap.
Signed-off-by: Jun Yao <yaojun8558363@...il.com>
---
arch/arm64/include/asm/pgalloc.h | 19 +++++++++++++++++++
arch/arm64/kernel/vmlinux.lds.S | 32 ++++++++++++++++++--------------
arch/arm64/mm/mmu.c | 23 +++++++++++++++++++----
3 files changed, 56 insertions(+), 18 deletions(-)
diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgalloc.h
index 2e05bcd944c8..cc96a7e6957d 100644
--- a/arch/arm64/include/asm/pgalloc.h
+++ b/arch/arm64/include/asm/pgalloc.h
@@ -29,6 +29,10 @@
#define PGALLOC_GFP (GFP_KERNEL | __GFP_ZERO)
#define PGD_SIZE (PTRS_PER_PGD * sizeof(pgd_t))
+#if CONFIG_STRICT_KERNEL_RWX
+extern spinlock_t pgdir_lock;
+#endif
+
#if CONFIG_PGTABLE_LEVELS > 2
static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
@@ -78,6 +82,21 @@ static inline void __pgd_populate(pgd_t *pgdp, phys_addr_t pudp, pgdval_t prot)
static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgdp, pud_t *pudp)
{
+#if CONFIG_STRICT_KERNEL_RWX
+ if (mm == &init_mm) {
+ pgd_t *pgd;
+
+ spin_lock(&pgdir_lock);
+ pgd = pgd_set_fixmap(__pa_symbol(swapper_pg_dir));
+
+ pgd = (pgd_t *)((unsigned long)pgd + pgdp - swapper_pg_dir);
+ __pgd_populate(pgdp, __pa(pudp), PUD_TYPE_TABLE);
+
+ pgd_clear_fixmap();
+ spin_unlock(&pgdir_lock);
+ return;
+ }
+#endif
__pgd_populate(pgdp, __pa(pudp), PUD_TYPE_TABLE);
}
#else
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 605d1b60469c..86532c57206a 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -216,21 +216,25 @@ SECTIONS
BSS_SECTION(0, 0, 0)
. = ALIGN(PAGE_SIZE);
- idmap_pg_dir = .;
- . += IDMAP_DIR_SIZE;
-#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
- tramp_pg_dir = .;
- . += PAGE_SIZE;
-#endif
-
-#ifdef CONFIG_ARM64_SW_TTBR0_PAN
- reserved_ttbr0 = .;
- . += RESERVED_TTBR0_SIZE;
-#endif
- swapper_pg_dir = .;
- . += SWAPPER_DIR_SIZE;
- swapper_pg_end = .;
+ .rodata : {
+ . = ALIGN(PAGE_SIZE);
+ idmap_pg_dir = .;
+ . += IDMAP_DIR_SIZE;
+
+ #ifdef CONFIG_UNMAP_KERNEL_AT_EL0
+ tramp_pg_dir = .;
+ . += PAGE_SIZE;
+ #endif
+
+ #ifdef CONFIG_ARM64_SW_TTBR0_PAN
+ reserved_ttbr0 = .;
+ . += RESERVED_TTBR0_SIZE;
+ #endif
+ swapper_pg_dir = .;
+ . += SWAPPER_DIR_SIZE;
+ swapper_pg_end = .;
+ }
__pecoff_data_size = ABSOLUTE(. - __initdata_begin);
_end = .;
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 2dbb2c9f1ec1..c1aa85a6ada5 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -66,6 +66,10 @@ static pte_t bm_pte[PTRS_PER_PTE] __page_aligned_bss;
static pmd_t bm_pmd[PTRS_PER_PMD] __page_aligned_bss __maybe_unused;
static pud_t bm_pud[PTRS_PER_PUD] __page_aligned_bss __maybe_unused;
+#ifdef CONFIG_STRICT_KERNEL_RWX
+DEFINE_SPINLOCK(pgdir_lock);
+#endif
+
pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
unsigned long size, pgprot_t vma_prot)
{
@@ -417,12 +421,22 @@ static void __init __map_memblock(pgd_t *pgdp, phys_addr_t start,
void __init mark_linear_text_alias_ro(void)
{
+ unsigned long size;
+
/*
* Remove the write permissions from the linear alias of .text/.rodata
+ *
+ * We free some pages in .rodata at paging_init(), which generates a
+ * hole. And the hole splits .rodata into two pieces.
*/
+ size = (unsigned long)swapper_pg_dir + PAGE_SIZE - (unsigned long)_text;
update_mapping_prot(__pa_symbol(_text), (unsigned long)lm_alias(_text),
- (unsigned long)__init_begin - (unsigned long)_text,
- PAGE_KERNEL_RO);
+ size, PAGE_KERNEL_RO);
+
+ size = (unsigned long)__init_begin - (unsigned long)swapper_pg_end;
+ update_mapping_prot(__pa_symbol(swapper_pg_end),
+ (unsigned long)lm_alias(swapper_pg_end),
+ size, PAGE_KERNEL_RO);
}
static void __init map_mem(pgd_t *pgdp)
@@ -587,8 +601,9 @@ static void __init map_kernel(pgd_t *pgdp)
*/
map_kernel_segment(pgdp, _text, _etext, text_prot, &vmlinux_text, 0,
VM_NO_GUARD);
- map_kernel_segment(pgdp, __start_rodata, __inittext_begin, PAGE_KERNEL,
- &vmlinux_rodata, NO_CONT_MAPPINGS, VM_NO_GUARD);
+ map_kernel_segment(pgdp, __start_rodata, __inittext_begin,
+ PAGE_KERNEL, &vmlinux_rodata,
+ NO_CONT_MAPPINGS | NO_BLOCK_MAPPINGS, VM_NO_GUARD);
map_kernel_segment(pgdp, __inittext_begin, __inittext_end, text_prot,
&vmlinux_inittext, 0, VM_NO_GUARD);
map_kernel_segment(pgdp, __initdata_begin, __initdata_end, PAGE_KERNEL,
--
2.17.1
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