[v7,6/7] ARM: Initialize the mapping of KASan shadow memory
diff mbox series

Message ID 20200117224839.23531-7-f.fainelli@gmail.com
State New
Headers show
Series
  • KASan for arm
Related show

Commit Message

Florian Fainelli Jan. 17, 2020, 10:48 p.m. UTC
From: Andrey Ryabinin <aryabinin@virtuozzo.com>

This patch initializes KASan shadow region's page table and memory.
There are two stage for KASan initializing:

1. At early boot stage the whole shadow region is mapped to just
   one physical page (kasan_zero_page). It is finished by the function
   kasan_early_init which is called by __mmap_switched(arch/arm/kernel/
   head-common.S)
             ---Andrey Ryabinin <aryabinin@virtuozzo.com>

2. After the calling of paging_init, we use kasan_zero_page as zero
   shadow for some memory that KASan does not need to track, and we
   allocate a new shadow space for the other memory that KASan need to
   track. These issues are finished by the function kasan_init which is
   call by setup_arch.
            ---Andrey Ryabinin <aryabinin@virtuozzo.com>

3. Add support ARM LPAE
   If LPAE is enabled, KASan shadow region's mapping table need be copied
   in the pgd_alloc() function.
            ---Abbott Liu <liuwenliang@huawei.com>

4. Change kasan_pte_populate,kasan_pmd_populate,kasan_pud_populate,
   kasan_pgd_populate from .meminit.text section to .init.text section.
           ---Reported by: Florian Fainelli <f.fainelli@gmail.com>
           ---Signed off by: Abbott Liu <liuwenliang@huawei.com>

Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Co-Developed-by: Abbott Liu <liuwenliang@huawei.com>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Reported-by: Russell King - ARM Linux <linux@armlinux.org.uk>
Reported-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Abbott Liu <liuwenliang@huawei.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 arch/arm/include/asm/kasan.h       |  35 ++++
 arch/arm/include/asm/pgalloc.h     |   9 +-
 arch/arm/include/asm/thread_info.h |   4 +
 arch/arm/kernel/head-common.S      |   3 +
 arch/arm/kernel/setup.c            |   2 +
 arch/arm/mm/Makefile               |   3 +
 arch/arm/mm/kasan_init.c           | 302 +++++++++++++++++++++++++++++
 arch/arm/mm/pgd.c                  |  14 ++
 8 files changed, 370 insertions(+), 2 deletions(-)
 create mode 100644 arch/arm/include/asm/kasan.h
 create mode 100644 arch/arm/mm/kasan_init.c

Patch
diff mbox series

diff --git a/arch/arm/include/asm/kasan.h b/arch/arm/include/asm/kasan.h
new file mode 100644
index 000000000000..1801f4d30993
--- /dev/null
+++ b/arch/arm/include/asm/kasan.h
@@ -0,0 +1,35 @@ 
+/*
+ * arch/arm/include/asm/kasan.h
+ *
+ * Copyright (c) 2015 Samsung Electronics Co., Ltd.
+ * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#ifndef __ASM_KASAN_H
+#define __ASM_KASAN_H
+
+#ifdef CONFIG_KASAN
+
+#include <asm/kasan_def.h>
+
+#define KASAN_SHADOW_SCALE_SHIFT 3
+
+/*
+ * Compiler uses shadow offset assuming that addresses start
+ * from 0. Kernel addresses don't start from 0, so shadow
+ * for kernel really starts from 'compiler's shadow offset' +
+ * ('kernel address space start' >> KASAN_SHADOW_SCALE_SHIFT)
+ */
+
+extern void kasan_init(void);
+
+#else
+static inline void kasan_init(void) { }
+#endif
+
+#endif
diff --git a/arch/arm/include/asm/pgalloc.h b/arch/arm/include/asm/pgalloc.h
index 069da393110c..d969f8058b26 100644
--- a/arch/arm/include/asm/pgalloc.h
+++ b/arch/arm/include/asm/pgalloc.h
@@ -21,6 +21,7 @@ 
 #define _PAGE_KERNEL_TABLE	(PMD_TYPE_TABLE | PMD_BIT4 | PMD_DOMAIN(DOMAIN_KERNEL))
 
 #ifdef CONFIG_ARM_LPAE
+#define PGD_SIZE		(PTRS_PER_PGD * sizeof(pgd_t))
 
 static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
 {
@@ -39,14 +40,18 @@  static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
 }
 
 #else	/* !CONFIG_ARM_LPAE */
+#define PGD_SIZE		(PAGE_SIZE << 2)
 
 /*
  * Since we have only two-level page tables, these are trivial
  */
 #define pmd_alloc_one(mm,addr)		({ BUG(); ((pmd_t *)2); })
 #define pmd_free(mm, pmd)		do { } while (0)
-#define pud_populate(mm,pmd,pte)	BUG()
-
+#ifndef CONFIG_KASAN
+#define pud_populate(mm, pmd, pte)	BUG()
+#else
+#define pud_populate(mm, pmd, pte)	do { } while (0)
+#endif
 #endif	/* CONFIG_ARM_LPAE */
 
 extern pgd_t *pgd_alloc(struct mm_struct *mm);
diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index 0d0d5178e2c3..2c940dcc953b 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -13,7 +13,11 @@ 
 #include <asm/fpstate.h>
 #include <asm/page.h>
 
+#ifdef CONFIG_KASAN
+#define THREAD_SIZE_ORDER	2
+#else
 #define THREAD_SIZE_ORDER	1
+#endif
 #define THREAD_SIZE		(PAGE_SIZE << THREAD_SIZE_ORDER)
 #define THREAD_START_SP		(THREAD_SIZE - 8)
 
diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S
index 6840c7c60a85..89c80154b9ef 100644
--- a/arch/arm/kernel/head-common.S
+++ b/arch/arm/kernel/head-common.S
@@ -111,6 +111,9 @@  __mmap_switched:
 	str	r8, [r2]			@ Save atags pointer
 	cmp	r3, #0
 	strne	r10, [r3]			@ Save control register values
+#ifdef CONFIG_KASAN
+	bl	kasan_early_init
+#endif
 	mov	lr, #0
 	b	start_kernel
 ENDPROC(__mmap_switched)
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index d0a464e317ea..b120df6325dc 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -58,6 +58,7 @@ 
 #include <asm/unwind.h>
 #include <asm/memblock.h>
 #include <asm/virt.h>
+#include <asm/kasan.h>
 
 #include "atags.h"
 
@@ -1130,6 +1131,7 @@  void __init setup_arch(char **cmdline_p)
 	early_ioremap_reset();
 
 	paging_init(mdesc);
+	kasan_init();
 	request_standard_resources(mdesc);
 
 	if (mdesc->restart)
diff --git a/arch/arm/mm/Makefile b/arch/arm/mm/Makefile
index 432302911d6e..1c937135c9c4 100644
--- a/arch/arm/mm/Makefile
+++ b/arch/arm/mm/Makefile
@@ -112,3 +112,6 @@  obj-$(CONFIG_CACHE_L2X0_PMU)	+= cache-l2x0-pmu.o
 obj-$(CONFIG_CACHE_XSC3L2)	+= cache-xsc3l2.o
 obj-$(CONFIG_CACHE_TAUROS2)	+= cache-tauros2.o
 obj-$(CONFIG_CACHE_UNIPHIER)	+= cache-uniphier.o
+
+KASAN_SANITIZE_kasan_init.o    := n
+obj-$(CONFIG_KASAN)            += kasan_init.o
diff --git a/arch/arm/mm/kasan_init.c b/arch/arm/mm/kasan_init.c
new file mode 100644
index 000000000000..7597efb36cb0
--- /dev/null
+++ b/arch/arm/mm/kasan_init.c
@@ -0,0 +1,302 @@ 
+/*
+ * This file contains kasan initialization code for ARM.
+ *
+ * Copyright (c) 2018 Samsung Electronics Co., Ltd.
+ * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#define pr_fmt(fmt) "kasan: " fmt
+#include <linux/kasan.h>
+#include <linux/kernel.h>
+#include <linux/memblock.h>
+#include <linux/sched/task.h>
+#include <linux/start_kernel.h>
+#include <asm/cputype.h>
+#include <asm/highmem.h>
+#include <asm/mach/map.h>
+#include <asm/memory.h>
+#include <asm/page.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/procinfo.h>
+#include <asm/proc-fns.h>
+#include <asm/tlbflush.h>
+#include <asm/cp15.h>
+
+#include "mm.h"
+
+static pgd_t tmp_pgd_table[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE);
+
+pmd_t tmp_pmd_table[PTRS_PER_PMD] __page_aligned_bss;
+
+static __init void *kasan_alloc_block(size_t size, int node)
+{
+	return memblock_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
+				      MEMBLOCK_ALLOC_KASAN, node);
+}
+
+static void __init kasan_early_pmd_populate(unsigned long start,
+					unsigned long end, pud_t *pud)
+{
+	unsigned long addr;
+	unsigned long next;
+	pmd_t *pmd;
+
+	pmd = pmd_offset(pud, start);
+	for (addr = start; addr < end;) {
+		pmd_populate_kernel(&init_mm, pmd, kasan_early_shadow_pte);
+		next = pmd_addr_end(addr, end);
+		addr = next;
+		flush_pmd_entry(pmd);
+		pmd++;
+	}
+}
+
+static void __init kasan_early_pud_populate(unsigned long start,
+				unsigned long end, pgd_t *pgd)
+{
+	unsigned long addr;
+	unsigned long next;
+	pud_t *pud;
+
+	pud = pud_offset(pgd, start);
+	for (addr = start; addr < end;) {
+		next = pud_addr_end(addr, end);
+		kasan_early_pmd_populate(addr, next, pud);
+		addr = next;
+		pud++;
+	}
+}
+
+void __init kasan_map_early_shadow(pgd_t *pgdp)
+{
+	int i;
+	unsigned long start = KASAN_SHADOW_START;
+	unsigned long end = KASAN_SHADOW_END;
+	unsigned long addr;
+	unsigned long next;
+	pgd_t *pgd;
+
+	for (i = 0; i < PTRS_PER_PTE; i++)
+		set_pte_at(&init_mm, KASAN_SHADOW_START + i*PAGE_SIZE,
+			&kasan_early_shadow_pte[i], pfn_pte(
+				virt_to_pfn(kasan_early_shadow_page),
+				__pgprot(_L_PTE_DEFAULT | L_PTE_DIRTY
+					| L_PTE_XN)));
+
+	pgd = pgd_offset_k(start);
+	for (addr = start; addr < end;) {
+		next = pgd_addr_end(addr, end);
+		kasan_early_pud_populate(addr, next, pgd);
+		addr = next;
+		pgd++;
+	}
+}
+
+extern struct proc_info_list *lookup_processor_type(unsigned int);
+
+void __init kasan_early_init(void)
+{
+	struct proc_info_list *list;
+
+	/*
+	 * locate processor in the list of supported processor
+	 * types.  The linker builds this table for us from the
+	 * entries in arch/arm/mm/proc-*.S
+	 */
+	list = lookup_processor_type(read_cpuid_id());
+	if (list) {
+#ifdef MULTI_CPU
+		processor = *list->proc;
+#endif
+	}
+
+	BUILD_BUG_ON((KASAN_SHADOW_END - (1UL << 29)) != KASAN_SHADOW_OFFSET);
+	kasan_map_early_shadow(swapper_pg_dir);
+}
+
+static void __init clear_pgds(unsigned long start,
+			unsigned long end)
+{
+	for (; start && start < end; start += PMD_SIZE)
+		pmd_clear(pmd_off_k(start));
+}
+
+pte_t * __init kasan_pte_populate(pmd_t *pmd, unsigned long addr, int node)
+{
+	pte_t *pte = pte_offset_kernel(pmd, addr);
+
+	if (pte_none(*pte)) {
+		pte_t entry;
+		void *p = kasan_alloc_block(PAGE_SIZE, node);
+
+		if (!p)
+			return NULL;
+		entry = pfn_pte(virt_to_pfn(p),
+			__pgprot(pgprot_val(PAGE_KERNEL)));
+		set_pte_at(&init_mm, addr, pte, entry);
+	}
+	return pte;
+}
+
+pmd_t * __init kasan_pmd_populate(pud_t *pud, unsigned long addr, int node)
+{
+	pmd_t *pmd = pmd_offset(pud, addr);
+
+	if (pmd_none(*pmd)) {
+		void *p = kasan_alloc_block(PAGE_SIZE, node);
+
+		if (!p)
+			return NULL;
+		pmd_populate_kernel(&init_mm, pmd, p);
+	}
+	return pmd;
+}
+
+pud_t * __init kasan_pud_populate(pgd_t *pgd, unsigned long addr, int node)
+{
+	pud_t *pud = pud_offset(pgd, addr);
+
+	if (pud_none(*pud)) {
+		void *p = kasan_alloc_block(PAGE_SIZE, node);
+
+		if (!p)
+			return NULL;
+		pr_err("populating pud addr %lx\n", addr);
+		pud_populate(&init_mm, pud, p);
+	}
+	return pud;
+}
+
+pgd_t * __init kasan_pgd_populate(unsigned long addr, int node)
+{
+	pgd_t *pgd = pgd_offset_k(addr);
+
+	if (pgd_none(*pgd)) {
+		void *p = kasan_alloc_block(PAGE_SIZE, node);
+
+		if (!p)
+			return NULL;
+		pgd_populate(&init_mm, pgd, p);
+	}
+	return pgd;
+}
+
+static int __init create_mapping(unsigned long start, unsigned long end,
+				int node)
+{
+	unsigned long addr = start;
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+
+	pr_info("populating shadow for %lx, %lx\n", start, end);
+
+	for (; addr < end; addr += PAGE_SIZE) {
+		pgd = kasan_pgd_populate(addr, node);
+		if (!pgd)
+			return -ENOMEM;
+
+		pud = kasan_pud_populate(pgd, addr, node);
+		if (!pud)
+			return -ENOMEM;
+
+		pmd = kasan_pmd_populate(pud, addr, node);
+		if (!pmd)
+			return -ENOMEM;
+
+		pte = kasan_pte_populate(pmd, addr, node);
+		if (!pte)
+			return -ENOMEM;
+	}
+	return 0;
+}
+
+
+void __init kasan_init(void)
+{
+	struct memblock_region *reg;
+	u64 orig_ttbr0;
+	int i;
+
+	/*
+	 * We are going to perform proper setup of shadow memory.
+	 * At first we should unmap early shadow (clear_pgds() call bellow).
+	 * However, instrumented code couldn't execute without shadow memory.
+	 * tmp_pgd_table and tmp_pmd_table used to keep early shadow mapped
+	 * until full shadow setup will be finished.
+	 */
+	orig_ttbr0 = get_ttbr0();
+
+#ifdef CONFIG_ARM_LPAE
+	memcpy(tmp_pmd_table,
+		pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_START)),
+		sizeof(tmp_pmd_table));
+	memcpy(tmp_pgd_table, swapper_pg_dir, sizeof(tmp_pgd_table));
+	set_pgd(&tmp_pgd_table[pgd_index(KASAN_SHADOW_START)],
+		__pgd(__pa(tmp_pmd_table) | PMD_TYPE_TABLE | L_PGD_SWAPPER));
+	set_ttbr0(__pa(tmp_pgd_table));
+#else
+	memcpy(tmp_pgd_table, swapper_pg_dir, sizeof(tmp_pgd_table));
+	set_ttbr0((u64)__pa(tmp_pgd_table));
+#endif
+	flush_cache_all();
+	local_flush_bp_all();
+	local_flush_tlb_all();
+
+	clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
+
+	kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START),
+				    kasan_mem_to_shadow((void *)-1UL) + 1);
+
+	for_each_memblock(memory, reg) {
+		void *start = __va(reg->base);
+		void *end = __va(reg->base + reg->size);
+
+		if (reg->base + reg->size > arm_lowmem_limit)
+			end = __va(arm_lowmem_limit);
+		if (start >= end)
+			break;
+
+		create_mapping((unsigned long)kasan_mem_to_shadow(start),
+			(unsigned long)kasan_mem_to_shadow(end),
+			NUMA_NO_NODE);
+	}
+
+	/*1.the module's global variable is in MODULES_VADDR ~ MODULES_END,
+	 *  so we need mapping.
+	 *2.PKMAP_BASE ~ PKMAP_BASE+PMD_SIZE's shadow and MODULES_VADDR
+	 *  ~ MODULES_END's shadow is in the same PMD_SIZE, so we cant
+	 *  use kasan_populate_zero_shadow.
+	 */
+	create_mapping(
+		(unsigned long)kasan_mem_to_shadow((void *)MODULES_VADDR),
+
+		(unsigned long)kasan_mem_to_shadow((void *)(PKMAP_BASE +
+							PMD_SIZE)),
+		NUMA_NO_NODE);
+
+	/*
+	 * KAsan may reuse the contents of kasan_early_shadow_pte directly, so
+	 * we should make sure that it maps the zero page read-only.
+	 */
+	for (i = 0; i < PTRS_PER_PTE; i++)
+		set_pte_at(&init_mm, KASAN_SHADOW_START + i*PAGE_SIZE,
+			&kasan_early_shadow_pte[i],
+			pfn_pte(virt_to_pfn(kasan_early_shadow_page),
+				__pgprot(pgprot_val(PAGE_KERNEL)
+					| L_PTE_RDONLY)));
+	memset(kasan_early_shadow_page, 0, PAGE_SIZE);
+	set_ttbr0(orig_ttbr0);
+	flush_cache_all();
+	local_flush_bp_all();
+	local_flush_tlb_all();
+	pr_info("Kernel address sanitizer initialized\n");
+	init_task.kasan_depth = 0;
+}
diff --git a/arch/arm/mm/pgd.c b/arch/arm/mm/pgd.c
index 478bd2c6aa50..92a408262df2 100644
--- a/arch/arm/mm/pgd.c
+++ b/arch/arm/mm/pgd.c
@@ -61,6 +61,20 @@  pgd_t *pgd_alloc(struct mm_struct *mm)
 	new_pmd = pmd_alloc(mm, new_pud, 0);
 	if (!new_pmd)
 		goto no_pmd;
+#ifdef CONFIG_KASAN
+	/*
+	 *Copy PMD table for KASAN shadow mappings.
+	 */
+	init_pgd = pgd_offset_k(TASK_SIZE);
+	init_pud = pud_offset(init_pgd, TASK_SIZE);
+	init_pmd = pmd_offset(init_pud, TASK_SIZE);
+	new_pmd = pmd_offset(new_pud, TASK_SIZE);
+	memcpy(new_pmd, init_pmd,
+		(pmd_index(MODULES_VADDR)-pmd_index(TASK_SIZE))
+		* sizeof(pmd_t));
+	clean_dcache_area(new_pmd, PTRS_PER_PMD*sizeof(pmd_t));
+#endif
+
 #endif
 
 	if (!vectors_high()) {