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[92.34.215.146]) by smtp.gmail.com with ESMTPSA id c78sm5284434lfd.63.2020.06.15.02.05.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Jun 2020 02:05:00 -0700 (PDT) From: Linus Walleij To: Florian Fainelli , Abbott Liu , Russell King , Ard Biesheuvel , Andrey Ryabinin , Mike Rapoport Subject: [PATCH 4/5 v10] ARM: Initialize the mapping of KASan shadow memory Date: Mon, 15 Jun 2020 11:02:46 +0200 Message-Id: <20200615090247.5218-5-linus.walleij@linaro.org> X-Mailer: git-send-email 2.25.4 In-Reply-To: <20200615090247.5218-1-linus.walleij@linaro.org> References: <20200615090247.5218-1-linus.walleij@linaro.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200615_020505_575831_0BDD5232 X-CRM114-Status: GOOD ( 27.63 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Arnd Bergmann , Linus Walleij , kasan-dev@googlegroups.com, Alexander Potapenko , linux-arm-kernel@lists.infradead.org, Dmitry Vyukov Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.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 - 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 Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: kasan-dev@googlegroups.com Co-Developed-by: Abbott Liu Reviewed-by: Ard Biesheuvel Tested-by: Ard Biesheuvel # QEMU/KVM/mach-virt/LPAE/8G 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: Linus Walleij --- 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 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 + * + */ + +#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) + */ + +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 #include +#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 #include #include +#include #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 + */ + +#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, 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel