From: Linus Walleij
mainline inclusion
from mainline-5.11-rc1
commit 5615f69bc2097452ecc954f5264d784e158d6801
category: feature
feature: ARM KASAN support
issue: #I3ZXZF
CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
-------------------------------------------------
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)
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.
When using KASan we also need to increase the THREAD_SIZE_ORDER
from 1 to 2 as the extra calls for shadow memory uses quite a bit
of stack.
As we need to make a temporary copy of the PGD when setting up
shadow memory we create a helpful PGD_SIZE definition for both
LPAE and non-LPAE setups.
The KASan core code unconditionally calls pud_populate() so this
needs to be changed from BUG() to do {} while (0) when building
with KASan enabled.
After the initial development by Andre Ryabinin several modifications
have been made to this code:
Abbott Liu
- Add support ARM LPAE: If LPAE is enabled, KASan shadow region's
mapping table need be copied in the pgd_alloc() function.
- 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
Linus Walleij :
- Drop the custom mainpulation of TTBR0 and just use
cpu_switch_mm() to switch the pgd table.
- Adopt to handle 4th level page tabel folding.
- Rewrite the entire page directory and page entry initialization
sequence to be recursive based on ARM64:s kasan_init.c.
Ard Biesheuvel :
- Necessary underlying fixes.
- Crucial bug fixes to the memory set-up code.
Co-developed-by: Andrey Ryabinin
Co-developed-by: Abbott Liu
Co-developed-by: Ard Biesheuvel
Cc: Alexander Potapenko
Cc: Dmitry Vyukov
Cc: kasan-dev@googlegroups.com
Cc: Mike Rapoport
Acked-by: Mike Rapoport
Reviewed-by: Ard Biesheuvel
Tested-by: Ard Biesheuvel # QEMU/KVM/mach-virt/LPAE/8G
Tested-by: Florian Fainelli # Brahma SoCs
Tested-by: Ahmad Fatoum # i.MX6Q
Reported-by: Russell King - ARM Linux
Reported-by: Florian Fainelli
Signed-off-by: Andrey Ryabinin
Signed-off-by: Abbott Liu
Signed-off-by: Florian Fainelli
Signed-off-by: Ard Biesheuvel
Signed-off-by: Linus Walleij
Signed-off-by: Russell King
(cherry picked from commit 5615f69bc2097452ecc954f5264d784e158d6801)
Signed-off-by: Kefeng Wang
Reviewed-by: Jing Xiangfeng
Signed-off-by: Chen Jun
Signed-off-by: Yu Changchun
---
arch/arm/include/asm/kasan.h | 33 ++++
arch/arm/include/asm/pgalloc.h | 8 +-
arch/arm/include/asm/thread_info.h | 8 +
arch/arm/kernel/head-common.S | 3 +
arch/arm/kernel/setup.c | 2 +
arch/arm/mm/Makefile | 3 +
arch/arm/mm/kasan_init.c | 291 +++++++++++++++++++++++++++++
arch/arm/mm/pgd.c | 16 +-
8 files changed, 362 insertions(+), 2 deletions(-)
create mode 100644 arch/arm/include/asm/kasan.h
create mode 100644 arch/arm/mm/kasan_init.c
diff --git a/arch/arm/include/asm/kasan.h b/arch/arm/include/asm/kasan.h
new file mode 100644
index 000000000000..303c35df3135
--- /dev/null
+++ b/arch/arm/include/asm/kasan.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * arch/arm/include/asm/kasan.h
+ *
+ * Copyright (c) 2015 Samsung Electronics Co., Ltd.
+ * Author: Andrey Ryabinin
+ *
+ */
+
+#ifndef __ASM_KASAN_H
+#define __ASM_KASAN_H
+
+#ifdef CONFIG_KASAN
+
+#include
+
+#define KASAN_SHADOW_SCALE_SHIFT 3
+
+/*
+ * The compiler uses a 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)
+ */
+
+asmlinkage void kasan_early_init(void);
+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 15f4674715f8..fdee1f04f4f3 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 void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
{
@@ -28,14 +29,19 @@ 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)
+#ifdef CONFIG_KASAN
+/* The KASan core unconditionally calls pud_populate() on all architectures */
+#define pud_populate(mm,pmd,pte) do { } while (0)
+#else
#define pud_populate(mm,pmd,pte) BUG()
-
+#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 536b6b979f63..56fae7861fd3 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -13,7 +13,15 @@
#include
#include
+#ifdef CONFIG_KASAN
+/*
+ * KASan uses a lot of extra stack space so the thread size order needs to
+ * be increased.
+ */
+#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 f90479d8b50c..d32f7652a5bf 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -59,6 +59,7 @@
#include
#include
#include
+#include
#include "atags.h"
@@ -1145,6 +1146,7 @@ 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 99699c32d8a5..4536159bc8fa 100644
--- a/arch/arm/mm/Makefile
+++ b/arch/arm/mm/Makefile
@@ -113,3 +113,6 @@ 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..9c348042a724
--- /dev/null
+++ b/arch/arm/mm/kasan_init.c
@@ -0,0 +1,291 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * This file contains kasan initialization code for ARM.
+ *
+ * Copyright (c) 2018 Samsung Electronics Co., Ltd.
+ * Author: Andrey Ryabinin
+ * Author: Linus Walleij
+ */
+
+#define pr_fmt(fmt) "kasan: " fmt
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+
+#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)
+{
+ return memblock_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
+ MEMBLOCK_ALLOC_KASAN, NUMA_NO_NODE);
+}
+
+static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
+ unsigned long end, bool early)
+{
+ unsigned long next;
+ pte_t *ptep = pte_offset_kernel(pmdp, addr);
+
+ do {
+ pte_t entry;
+ void *p;
+
+ next = addr + PAGE_SIZE;
+
+ if (!early) {
+ if (!pte_none(READ_ONCE(*ptep)))
+ continue;
+
+ p = kasan_alloc_block(PAGE_SIZE);
+ if (!p) {
+ panic("%s failed to allocate shadow page for address 0x%lx\n",
+ __func__, addr);
+ return;
+ }
+ memset(p, KASAN_SHADOW_INIT, PAGE_SIZE);
+ entry = pfn_pte(virt_to_pfn(p),
+ __pgprot(pgprot_val(PAGE_KERNEL)));
+ } else if (pte_none(READ_ONCE(*ptep))) {
+ /*
+ * The early shadow memory is mapping all KASan
+ * operations to one and the same page in memory,
+ * "kasan_early_shadow_page" so that the instrumentation
+ * will work on a scratch area until we can set up the
+ * proper KASan shadow memory.
+ */
+ entry = pfn_pte(virt_to_pfn(kasan_early_shadow_page),
+ __pgprot(_L_PTE_DEFAULT | L_PTE_DIRTY | L_PTE_XN));
+ } else {
+ /*
+ * Early shadow mappings are PMD_SIZE aligned, so if the
+ * first entry is already set, they must all be set.
+ */
+ return;
+ }
+
+ set_pte_at(&init_mm, addr, ptep, entry);
+ } while (ptep++, addr = next, addr != end);
+}
+
+/*
+ * The pmd (page middle directory) is only used on LPAE
+ */
+static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
+ unsigned long end, bool early)
+{
+ unsigned long next;
+ pmd_t *pmdp = pmd_offset(pudp, addr);
+
+ do {
+ if (pmd_none(*pmdp)) {
+ /*
+ * We attempt to allocate a shadow block for the PMDs
+ * used by the PTEs for this address if it isn't already
+ * allocated.
+ */
+ void *p = early ? kasan_early_shadow_pte :
+ kasan_alloc_block(PAGE_SIZE);
+
+ if (!p) {
+ panic("%s failed to allocate shadow block for address 0x%lx\n",
+ __func__, addr);
+ return;
+ }
+ pmd_populate_kernel(&init_mm, pmdp, p);
+ flush_pmd_entry(pmdp);
+ }
+
+ next = pmd_addr_end(addr, end);
+ kasan_pte_populate(pmdp, addr, next, early);
+ } while (pmdp++, addr = next, addr != end);
+}
+
+static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
+ bool early)
+{
+ unsigned long next;
+ pgd_t *pgdp;
+ p4d_t *p4dp;
+ pud_t *pudp;
+
+ pgdp = pgd_offset_k(addr);
+
+ do {
+ /*
+ * Allocate and populate the shadow block of p4d folded into
+ * pud folded into pmd if it doesn't already exist
+ */
+ if (!early && pgd_none(*pgdp)) {
+ void *p = kasan_alloc_block(PAGE_SIZE);
+
+ if (!p) {
+ panic("%s failed to allocate shadow block for address 0x%lx\n",
+ __func__, addr);
+ return;
+ }
+ pgd_populate(&init_mm, pgdp, p);
+ }
+
+ next = pgd_addr_end(addr, end);
+ /*
+ * We just immediately jump over the p4d and pud page
+ * directories since we believe ARM32 will never gain four
+ * nor five level page tables.
+ */
+ p4dp = p4d_offset(pgdp, addr);
+ pudp = pud_offset(p4dp, addr);
+
+ kasan_pmd_populate(pudp, addr, next, early);
+ } while (pgdp++, addr = next, addr != end);
+}
+
+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);
+ /*
+ * We walk the page table and set all of the shadow memory to point
+ * to the scratch page.
+ */
+ kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, true);
+}
+
+static void __init clear_pgds(unsigned long start,
+ unsigned long end)
+{
+ for (; start && start < end; start += PMD_SIZE)
+ pmd_clear(pmd_off_k(start));
+}
+
+static int __init create_mapping(void *start, void *end)
+{
+ void *shadow_start, *shadow_end;
+
+ shadow_start = kasan_mem_to_shadow(start);
+ shadow_end = kasan_mem_to_shadow(end);
+
+ pr_info("Mapping kernel virtual memory block: %px-%px at shadow: %px-%px\n",
+ start, end, shadow_start, shadow_end);
+
+ kasan_pgd_populate((unsigned long)shadow_start & PAGE_MASK,
+ PAGE_ALIGN((unsigned long)shadow_end), false);
+ return 0;
+}
+
+void __init kasan_init(void)
+{
+ phys_addr_t pa_start, pa_end;
+ u64 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 can't execute without shadow memory.
+ *
+ * To keep the early shadow memory MMU tables around while setting up
+ * the proper shadow memory, we copy swapper_pg_dir (the initial page
+ * table) to tmp_pgd_table and use that to keep the early shadow memory
+ * mapped until the full shadow setup is finished. Then we swap back
+ * to the proper swapper_pg_dir.
+ */
+
+ memcpy(tmp_pgd_table, swapper_pg_dir, sizeof(tmp_pgd_table));
+#ifdef CONFIG_ARM_LPAE
+ /* We need to be in the same PGD or this won't work */
+ BUILD_BUG_ON(pgd_index(KASAN_SHADOW_START) !=
+ pgd_index(KASAN_SHADOW_END));
+ memcpy(tmp_pmd_table,
+ pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_START)),
+ sizeof(tmp_pmd_table));
+ set_pgd(&tmp_pgd_table[pgd_index(KASAN_SHADOW_START)],
+ __pgd(__pa(tmp_pmd_table) | PMD_TYPE_TABLE | L_PGD_SWAPPER));
+#endif
+ cpu_switch_mm(tmp_pgd_table, &init_mm);
+ 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_mem_range(i, &pa_start, &pa_end) {
+ void *start = __va(pa_start);
+ void *end = __va(pa_end);
+
+ /* Do not attempt to shadow highmem */
+ if (pa_start >= arm_lowmem_limit) {
+ pr_info("Skip highmem block at %pa-%pa\n", &pa_start, &pa_end);
+ continue;
+ }
+ if (pa_end > arm_lowmem_limit) {
+ pr_info("Truncating shadow for memory block at %pa-%pa to lowmem region at %pa\n",
+ &pa_start, &pa_end, &arm_lowmem_limit);
+ end = __va(arm_lowmem_limit);
+ }
+ if (start >= end) {
+ pr_info("Skipping invalid memory block %pa-%pa (virtual %p-%p)\n",
+ &pa_start, &pa_end, start, end);
+ continue;
+ }
+
+ create_mapping(start, end);
+ }
+
+ /*
+ * 1. The module global variables are in MODULES_VADDR ~ MODULES_END,
+ * so we need to map this area.
+ * 2. PKMAP_BASE ~ PKMAP_BASE+PMD_SIZE's shadow and MODULES_VADDR
+ * ~ MODULES_END's shadow is in the same PMD_SIZE, so we can't
+ * use kasan_populate_zero_shadow.
+ */
+ create_mapping((void *)MODULES_VADDR, (void *)(PKMAP_BASE + PMD_SIZE));
+
+ /*
+ * 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)));
+
+ cpu_switch_mm(swapper_pg_dir, &init_mm);
+ local_flush_tlb_all();
+
+ memset(kasan_early_shadow_page, 0, PAGE_SIZE);
+ 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 c5e1b27046a8..f8e9bc58a84f 100644
--- a/arch/arm/mm/pgd.c
+++ b/arch/arm/mm/pgd.c
@@ -66,7 +66,21 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
new_pmd = pmd_alloc(mm, new_pud, 0);
if (!new_pmd)
goto no_pmd;
-#endif
+#ifdef CONFIG_KASAN
+ /*
+ * Copy PMD table for KASAN shadow mappings.
+ */
+ init_pgd = pgd_offset_k(TASK_SIZE);
+ init_p4d = p4d_offset(init_pgd, TASK_SIZE);
+ init_pud = pud_offset(init_p4d, 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 /* CONFIG_KASAN */
+#endif /* CONFIG_LPAE */
if (!vectors_high()) {
/*
--
2.22.0
