From: Linus Walleij <linus.walleij@linaro.org>
To: Florian Fainelli <f.fainelli@gmail.com>,
Abbott Liu <liuwenliang@huawei.com>,
Russell King <linux@armlinux.org.uk>,
Ard Biesheuvel <ardb@kernel.org>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Mike Rapoport <rppt@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
Linus Walleij <linus.walleij@linaro.org>,
kasan-dev@googlegroups.com,
Alexander Potapenko <glider@google.com>,
linux-arm-kernel@lists.infradead.org,
Dmitry Vyukov <dvyukov@google.com>
Subject: [PATCH 4/5 v10] ARM: Initialize the mapping of KASan shadow memory
Date: Mon, 15 Jun 2020 11:02:46 +0200 [thread overview]
Message-ID: <20200615090247.5218-5-linus.walleij@linaro.org> (raw)
In-Reply-To: <20200615090247.5218-1-linus.walleij@linaro.org>
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.
After the initial development by Andre Ryabinin several modifications
have been made to this code:
Abbott Liu <liuwenliang@huawei.com>
- 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 <f.fainelli@gmail.com>
Linus Walleij <linus.walleij@linaro.org>:
- 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
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: kasan-dev@googlegroups.com
Co-Developed-by: Abbott Liu <liuwenliang@huawei.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Ard Biesheuvel <ardb@kernel.org> # QEMU/KVM/mach-virt/LPAE/8G
Reported-by: Russell King - ARM Linux <linux@armlinux.org.uk>
Reported-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Abbott Liu <liuwenliang@huawei.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
ChangeLog v9->v10:
- Rebase onto v5.8-rc1
- add support for folded p4d page tables, use the primitives necessary
for the 4th level folding, add (empty) walks of p4d level.
- Use the <linux/pgtable.h> header file that has now appeared as part
of the VM consolidation series.
- Use a recursive method to walk pgd/p4d/pud/pmd/pte instead of the
separate early/main calls and the flat call structure used in the
old code. This was inspired by the ARM64 KASan init code.
- Assume authorship of this code, I have now written the majority of
it so the blame is on me and noone else.
ChangeLog v8->v9:
- Drop the custom CP15 manipulation and cache flushing for swapping
TTBR0 and instead just use cpu_switch_mm().
- Collect Ard's tags.
ChangeLog v7->v8:
- Rebased.
ChangeLog v6->v7:
- Use SPDX identifer for the license.
- Move the TTBR0 accessor calls into this patch.
---
arch/arm/include/asm/kasan.h | 32 +++
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 | 304 +++++++++++++++++++++++++++++
arch/arm/mm/pgd.c | 15 +-
8 files changed, 369 insertions(+), 3 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..56b954db160e
--- /dev/null
+++ b/arch/arm/include/asm/kasan.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * arch/arm/include/asm/kasan.h
+ *
+ * Copyright (c) 2015 Samsung Electronics Co., Ltd.
+ * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
+ *
+ */
+
+#ifndef __ASM_KASAN_H
+#define __ASM_KASAN_H
+
+#ifdef CONFIG_KASAN
+
+#include <asm/kasan_def.h>
+
+#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)
+ */
+
+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 3609a6980c34..cf47cf9c4742 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 d8e18cdd96d3..b0820847bb92 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 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..6438a13f8368
--- /dev/null
+++ b/arch/arm/mm/kasan_init.c
@@ -0,0 +1,304 @@
+// 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 <ryabinin.a.a@gmail.com>
+ */
+
+#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 <linux/pgtable.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/procinfo.h>
+#include <asm/proc-fns.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_pte_populate(pmd_t *pmdp, unsigned long addr,
+ unsigned long end, int node, bool early)
+{
+ unsigned long next;
+ pte_t *ptep = pte_offset_kernel(pmdp, addr);
+
+ do {
+ next = addr + PAGE_SIZE;
+
+ if (pte_none(*ptep)) {
+ pte_t entry;
+ void *p;
+
+ /*
+ * 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.
+ */
+ if (early) {
+ p = kasan_early_shadow_page;
+ entry = pfn_pte(virt_to_pfn(kasan_early_shadow_page),
+ __pgprot(_L_PTE_DEFAULT | L_PTE_DIRTY
+ | L_PTE_XN));
+ } else {
+ p = kasan_alloc_block(PAGE_SIZE, node);
+ if (!p) {
+ panic("%s failed to alloc pte 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)));
+ }
+
+ set_pte_at(&init_mm, addr, ptep, entry);
+ }
+ } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep)));
+}
+
+/*
+ * The pmd (page middle directory) used on LPAE?
+ */
+static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
+ unsigned long end, int node, bool early)
+{
+ unsigned long next;
+ pmd_t *pmdp = pmd_offset(pudp, addr);
+
+ if (pmd_none(*pmdp)) {
+ void *p = early ? kasan_early_shadow_pte : kasan_alloc_block(PAGE_SIZE, node);
+
+ if (!p) {
+ panic("%s failed to allocate pmd for address 0x%lx\n",
+ __func__, addr);
+ return;
+ }
+ pmd_populate_kernel(&init_mm, pmdp, p);
+ flush_pmd_entry(pmdp);
+ }
+
+ do {
+ next = pmd_addr_end(addr, end);
+ kasan_pte_populate(pmdp, addr, next, node, early);
+ } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp)));
+}
+
+/*
+ * The pud (page upper directory) is only used on LPAE systems.
+ */
+static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr,
+ unsigned long end, int node, bool early)
+{
+ unsigned long next;
+ pud_t *pudp = pud_offset(p4dp, addr);
+
+ /*
+ * FIXME: necessary?
+ * Allocate and populate the PUD if it doesn't already exist
+ * On non-LPAE systems using just 2-level page tables pud_none()
+ * will always be zero and this will be skipped.
+ */
+ if (!early && pud_none(*pudp)) {
+ void *p = kasan_alloc_block(PAGE_SIZE, node);
+
+ if (!p) {
+ panic("%s failed to allocate pud for address 0x%lx\n",
+ __func__, addr);
+ return;
+ }
+ pr_info("populating pud addr %lx\n", addr);
+ pud_populate(&init_mm, pudp, p);
+ }
+
+ do {
+ next = pud_addr_end(addr, end);
+ kasan_pmd_populate(pudp, addr, next, node, early);
+ } while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp)));
+}
+
+/*
+ * The p4d (fourth level translation table) is unused on ARM32 but we iterate over it to
+ * please the Linux VMM.
+ */
+static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr,
+ unsigned long end, int node, bool early)
+{
+ unsigned long next;
+ p4d_t *p4dp = p4d_offset(pgdp, addr);
+
+ /* We do not check for p4d_none() as it is unused for sure */
+ if (p4d_none_or_clear_bad(p4dp)) {
+ panic("%s failed to populate p4d for address 0x%lx\n",
+ __func__, addr);
+ return;
+ }
+
+ do {
+ next = p4d_addr_end(addr, end);
+ kasan_pud_populate(p4dp, addr, next, node, early);
+ } while (p4dp++, addr = next, addr != end);
+}
+
+
+static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
+ int node, bool early)
+{
+ unsigned long next;
+ pgd_t *pgdp;
+
+ pgdp = pgd_offset_k(addr);
+
+ /* Allocate and populate the PGD if it doesn't already exist */
+ if (!early && pgd_none(*pgdp)) {
+ void *p = kasan_alloc_block(PAGE_SIZE, node);
+
+ if (!p) {
+ panic("%s failed to allocate pgd for address 0x%lx\n",
+ __func__, addr);
+ return;
+ }
+ pgd_populate(&init_mm, pgdp, p);
+ }
+
+ do {
+ next = pgd_addr_end(addr, end);
+ kasan_p4d_populate(pgdp, addr, next, node, 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, NUMA_NO_NODE,
+ 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(unsigned long start, unsigned long end,
+ int node)
+{
+ pr_info("populating shadow for %lx, %lx\n", start, end);
+ kasan_pgd_populate(start, end, NUMA_NO_NODE, false);
+ return 0;
+}
+
+void __init kasan_init(void)
+{
+ struct memblock_region *reg;
+ 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.
+ *
+ * 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.
+ */
+#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));
+ cpu_switch_mm(tmp_pgd_table, &init_mm);
+#else
+ memcpy(tmp_pgd_table, swapper_pg_dir, sizeof(tmp_pgd_table));
+ cpu_switch_mm(tmp_pgd_table, &init_mm);
+#endif
+ 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 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(
+ (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);
+ cpu_switch_mm(swapper_pg_dir, &init_mm);
+ 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..db5ef068e523 100644
--- a/arch/arm/mm/pgd.c
+++ b/arch/arm/mm/pgd.c
@@ -66,7 +66,20 @@ 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_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 /* CONFIG_KASAN */
+#endif /* CONFIG_LPAE */
if (!vectors_high()) {
/*
--
2.25.4
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next prev parent reply other threads:[~2020-06-15 9:14 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-15 9:02 [PATCH 0/5 v10] KASan for Arm Linus Walleij
2020-06-15 9:02 ` [PATCH 1/5 v10] ARM: Disable KASan instrumentation for some code Linus Walleij
2020-06-15 9:02 ` [PATCH 2/5 v10] ARM: Replace string mem* functions for KASan Linus Walleij
2020-06-15 9:02 ` [PATCH 3/5 v10] ARM: Define the virtual space of KASan's shadow region Linus Walleij
2020-06-15 9:02 ` Linus Walleij [this message]
2020-06-15 14:33 ` [PATCH 4/5 v10] ARM: Initialize the mapping of KASan shadow memory Mike Rapoport
2020-06-30 13:22 ` Linus Walleij
2020-06-30 14:45 ` Mike Rapoport
2020-06-29 14:07 ` Linus Walleij
2020-06-29 14:37 ` Russell King - ARM Linux admin
2020-06-30 9:38 ` Linus Walleij
2020-06-15 9:02 ` [PATCH 5/5 v10] ARM: Enable KASan for ARM Linus Walleij
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