From 42db5ed86090d8e57ca08bfd162a10be6320cc49 Mon Sep 17 00:00:00 2001 From: Vasily Gorbik Date: Fri, 17 Nov 2017 14:29:13 +0100 Subject: [PATCH] s390/kasan: add initialization code and enable it Kasan needs 1/8 of kernel virtual address space to be reserved as the shadow area. And eventually it requires the shadow memory offset to be known at compile time (passed to the compiler when full instrumentation is enabled). Any value picked as the shadow area offset for 3-level paging would eat up identity mapping on 4-level paging (with 1PB shadow area size). So, the kernel sticks to 3-level paging when kasan is enabled. 3TB border is picked as the shadow offset. The memory layout is adjusted so, that physical memory border does not exceed KASAN_SHADOW_START and vmemmap does not go below KASAN_SHADOW_END. Due to the fact that on s390 paging is set up very late and to cover more code with kasan instrumentation, temporary identity mapping and final shadow memory are set up early. The shadow memory mapping is later carried over to init_mm.pgd during paging_init. For the needs of paging structures allocation and shadow memory population a primitive allocator is used, which simply chops off memory blocks from the end of the physical memory. Kasan currenty doesn't track vmemmap and vmalloc areas. Current memory layout (for 3-level paging, 2GB physical memory). ---[ Identity Mapping ]--- 0x0000000000000000-0x0000000000100000 ---[ Kernel Image Start ]--- 0x0000000000100000-0x0000000002b00000 ---[ Kernel Image End ]--- 0x0000000002b00000-0x0000000080000000 2G <- physical memory border 0x0000000080000000-0x0000030000000000 3070G PUD I ---[ Kasan Shadow Start ]--- 0x0000030000000000-0x0000030010000000 256M PMD RW X <- shadow for 2G memory 0x0000030010000000-0x0000037ff0000000 523776M PTE RO NX <- kasan zero ro page 0x0000037ff0000000-0x0000038000000000 256M PMD RW X <- shadow for 2G modules ---[ Kasan Shadow End ]--- 0x0000038000000000-0x000003d100000000 324G PUD I ---[ vmemmap Area ]--- 0x000003d100000000-0x000003e080000000 ---[ vmalloc Area ]--- 0x000003e080000000-0x000003ff80000000 ---[ Modules Area ]--- 0x000003ff80000000-0x0000040000000000 2G Acked-by: Martin Schwidefsky Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky --- arch/s390/Kconfig | 1 + arch/s390/include/asm/kasan.h | 23 +++ arch/s390/include/asm/pgtable.h | 1 + arch/s390/kernel/early_nobss.c | 2 + arch/s390/kernel/setup.c | 22 ++- arch/s390/mm/Makefile | 3 + arch/s390/mm/init.c | 4 +- arch/s390/mm/kasan_init.c | 294 ++++++++++++++++++++++++++++++++ 8 files changed, 343 insertions(+), 7 deletions(-) create mode 100644 arch/s390/include/asm/kasan.h create mode 100644 arch/s390/mm/kasan_init.c diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 6061dd7578fe..95fff775ac7c 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -120,6 +120,7 @@ config S390 select HAVE_ALIGNED_STRUCT_PAGE if SLUB select HAVE_ARCH_AUDITSYSCALL select HAVE_ARCH_JUMP_LABEL + select HAVE_ARCH_KASAN select CPU_NO_EFFICIENT_FFS if !HAVE_MARCH_Z9_109_FEATURES select HAVE_ARCH_SECCOMP_FILTER select HAVE_ARCH_SOFT_DIRTY diff --git a/arch/s390/include/asm/kasan.h b/arch/s390/include/asm/kasan.h new file mode 100644 index 000000000000..7de6eceb562e --- /dev/null +++ b/arch/s390/include/asm/kasan.h @@ -0,0 +1,23 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_KASAN_H +#define __ASM_KASAN_H + +#include + +#ifdef CONFIG_KASAN + +#define KASAN_SHADOW_SCALE_SHIFT 3 +#define KASAN_SHADOW_SIZE \ + (_AC(1, UL) << (_REGION2_SHIFT - KASAN_SHADOW_SCALE_SHIFT)) +#define KASAN_SHADOW_OFFSET _AC(0x30000000000, UL) +#define KASAN_SHADOW_START KASAN_SHADOW_OFFSET +#define KASAN_SHADOW_END (KASAN_SHADOW_START + KASAN_SHADOW_SIZE) + +extern void kasan_early_init(void); +extern void kasan_copy_shadow(pgd_t *dst); +#else +static inline void kasan_early_init(void) { } +static inline void kasan_copy_shadow(pgd_t *dst) { } +#endif + +#endif diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index 5f0fb9320dd0..3baf8f1fb8f2 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -1181,6 +1181,7 @@ static inline pte_t mk_pte(struct page *page, pgprot_t pgprot) #define pgd_offset(mm, address) ((mm)->pgd + pgd_index(address)) #define pgd_offset_k(address) pgd_offset(&init_mm, address) +#define pgd_offset_raw(pgd, addr) ((pgd) + pgd_index(addr)) #define pmd_deref(pmd) (pmd_val(pmd) & _SEGMENT_ENTRY_ORIGIN) #define pud_deref(pud) (pud_val(pud) & _REGION_ENTRY_ORIGIN) diff --git a/arch/s390/kernel/early_nobss.c b/arch/s390/kernel/early_nobss.c index 8e96590b3a68..8d73f7fae16e 100644 --- a/arch/s390/kernel/early_nobss.c +++ b/arch/s390/kernel/early_nobss.c @@ -14,6 +14,7 @@ #include #include #include +#include #include "entry.h" static void __init reset_tod_clock(void) @@ -40,4 +41,5 @@ void __init startup_init_nobss(void) { reset_tod_clock(); clear_bss_section(); + kasan_early_init(); } diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c index ae3810c04872..93cf9bce98a1 100644 --- a/arch/s390/kernel/setup.c +++ b/arch/s390/kernel/setup.c @@ -531,14 +531,19 @@ static void __init setup_memory_end(void) { unsigned long vmax, vmalloc_size, tmp; - /* Choose kernel address space layout: 2, 3, or 4 levels. */ + /* Choose kernel address space layout: 3 or 4 levels. */ vmalloc_size = VMALLOC_END ?: (128UL << 30) - MODULES_LEN; - tmp = (memory_end ?: max_physmem_end) / PAGE_SIZE; - tmp = tmp * (sizeof(struct page) + PAGE_SIZE); - if (tmp + vmalloc_size + MODULES_LEN <= _REGION2_SIZE) + if (IS_ENABLED(CONFIG_KASAN)) { vmax = _REGION2_SIZE; /* 3-level kernel page table */ - else - vmax = _REGION1_SIZE; /* 4-level kernel page table */ + } else { + tmp = (memory_end ?: max_physmem_end) / PAGE_SIZE; + tmp = tmp * (sizeof(struct page) + PAGE_SIZE); + if (tmp + vmalloc_size + MODULES_LEN <= _REGION2_SIZE) + vmax = _REGION2_SIZE; /* 3-level kernel page table */ + else + vmax = _REGION1_SIZE; /* 4-level kernel page table */ + } + /* module area is at the end of the kernel address space. */ MODULES_END = vmax; MODULES_VADDR = MODULES_END - MODULES_LEN; @@ -556,6 +561,11 @@ static void __init setup_memory_end(void) /* Take care that memory_end is set and <= vmemmap */ memory_end = min(memory_end ?: max_physmem_end, tmp); +#ifdef CONFIG_KASAN + /* fit in kasan shadow memory region between 1:1 and vmemmap */ + memory_end = min(memory_end, KASAN_SHADOW_START); + vmemmap = max(vmemmap, (struct page *)KASAN_SHADOW_END); +#endif max_pfn = max_low_pfn = PFN_DOWN(memory_end); memblock_remove(memory_end, ULONG_MAX); diff --git a/arch/s390/mm/Makefile b/arch/s390/mm/Makefile index 83c83c69cab2..f5880bfd1b0c 100644 --- a/arch/s390/mm/Makefile +++ b/arch/s390/mm/Makefile @@ -10,3 +10,6 @@ obj-$(CONFIG_CMM) += cmm.o obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o obj-$(CONFIG_S390_PTDUMP) += dump_pagetables.o obj-$(CONFIG_PGSTE) += gmap.o + +KASAN_SANITIZE_kasan_init.o := n +obj-$(CONFIG_KASAN) += kasan_init.o diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c index 3fa3e5323612..50ebda9b3d0c 100644 --- a/arch/s390/mm/init.c +++ b/arch/s390/mm/init.c @@ -42,6 +42,7 @@ #include #include #include +#include pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(.bss..swapper_pg_dir); @@ -98,8 +99,9 @@ void __init paging_init(void) S390_lowcore.user_asce = S390_lowcore.kernel_asce; crst_table_init((unsigned long *) init_mm.pgd, pgd_type); vmem_map_init(); + kasan_copy_shadow(init_mm.pgd); - /* enable virtual mapping in kernel mode */ + /* enable virtual mapping in kernel mode */ __ctl_load(S390_lowcore.kernel_asce, 1, 1); __ctl_load(S390_lowcore.kernel_asce, 7, 7); __ctl_load(S390_lowcore.kernel_asce, 13, 13); diff --git a/arch/s390/mm/kasan_init.c b/arch/s390/mm/kasan_init.c new file mode 100644 index 000000000000..b888cbbbcf0d --- /dev/null +++ b/arch/s390/mm/kasan_init.c @@ -0,0 +1,294 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static unsigned long pgalloc_pos __initdata; +static unsigned long pgalloc_low __initdata; + +#define __sha(x) ((unsigned long)kasan_mem_to_shadow((void *)x)) + +static pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE); + +static void __init kasan_early_panic(const char *reason) +{ + sclp_early_printk("The Linux kernel failed to boot with the KernelAddressSanitizer:\n"); + sclp_early_printk(reason); + disabled_wait(0); +} + +static void * __init kasan_early_alloc_pages(unsigned int order) +{ + pgalloc_pos -= (PAGE_SIZE << order); + + if (pgalloc_pos < pgalloc_low) + kasan_early_panic("out of memory during initialisation\n"); + + return (void *)pgalloc_pos; +} + +static void * __init kasan_early_crst_alloc(unsigned long val) +{ + unsigned long *table; + + table = kasan_early_alloc_pages(CRST_ALLOC_ORDER); + if (table) + crst_table_init(table, val); + return table; +} + +static pte_t * __init kasan_early_pte_alloc(void) +{ + static void *pte_leftover; + pte_t *pte; + + BUILD_BUG_ON(_PAGE_TABLE_SIZE * 2 != PAGE_SIZE); + + if (!pte_leftover) { + pte_leftover = kasan_early_alloc_pages(0); + pte = pte_leftover + _PAGE_TABLE_SIZE; + } else { + pte = pte_leftover; + pte_leftover = NULL; + } + memset64((u64 *)pte, _PAGE_INVALID, PTRS_PER_PTE); + return pte; +} + +enum populate_mode { + POPULATE_ONE2ONE, + POPULATE_MAP, + POPULATE_ZERO_SHADOW +}; +static void __init kasan_early_vmemmap_populate(unsigned long address, + unsigned long end, + enum populate_mode mode) +{ + unsigned long pgt_prot_zero, pgt_prot; + pgd_t *pg_dir; + p4d_t *p4_dir; + pud_t *pu_dir; + pmd_t *pm_dir; + pte_t *pt_dir; + + pgt_prot_zero = pgprot_val(PAGE_KERNEL_RO); + pgt_prot_zero &= ~_PAGE_NOEXEC; + pgt_prot = pgprot_val(PAGE_KERNEL_EXEC); + + while (address < end) { + pg_dir = pgd_offset_k(address); + if (pgd_none(*pg_dir)) { + if (mode == POPULATE_ZERO_SHADOW && + IS_ALIGNED(address, PGDIR_SIZE) && + end - address >= PGDIR_SIZE) { + pgd_populate(&init_mm, pg_dir, kasan_zero_p4d); + address = (address + PGDIR_SIZE) & PGDIR_MASK; + continue; + } + p4_dir = kasan_early_crst_alloc(_REGION2_ENTRY_EMPTY); + pgd_populate(&init_mm, pg_dir, p4_dir); + } + + p4_dir = p4d_offset(pg_dir, address); + if (p4d_none(*p4_dir)) { + if (mode == POPULATE_ZERO_SHADOW && + IS_ALIGNED(address, P4D_SIZE) && + end - address >= P4D_SIZE) { + p4d_populate(&init_mm, p4_dir, kasan_zero_pud); + address = (address + P4D_SIZE) & P4D_MASK; + continue; + } + pu_dir = kasan_early_crst_alloc(_REGION3_ENTRY_EMPTY); + p4d_populate(&init_mm, p4_dir, pu_dir); + } + + pu_dir = pud_offset(p4_dir, address); + if (pud_none(*pu_dir)) { + if (mode == POPULATE_ZERO_SHADOW && + IS_ALIGNED(address, PUD_SIZE) && + end - address >= PUD_SIZE) { + pud_populate(&init_mm, pu_dir, kasan_zero_pmd); + address = (address + PUD_SIZE) & PUD_MASK; + continue; + } + pm_dir = kasan_early_crst_alloc(_SEGMENT_ENTRY_EMPTY); + pud_populate(&init_mm, pu_dir, pm_dir); + } + + pm_dir = pmd_offset(pu_dir, address); + if (pmd_none(*pm_dir)) { + if (mode == POPULATE_ZERO_SHADOW && + IS_ALIGNED(address, PMD_SIZE) && + end - address >= PMD_SIZE) { + pmd_populate(&init_mm, pm_dir, kasan_zero_pte); + address = (address + PMD_SIZE) & PMD_MASK; + continue; + } + pt_dir = kasan_early_pte_alloc(); + pmd_populate(&init_mm, pm_dir, pt_dir); + } + + pt_dir = pte_offset_kernel(pm_dir, address); + if (pte_none(*pt_dir)) { + void *page; + + switch (mode) { + case POPULATE_ONE2ONE: + page = (void *)address; + pte_val(*pt_dir) = __pa(page) | pgt_prot; + break; + case POPULATE_MAP: + page = kasan_early_alloc_pages(0); + memset(page, 0, PAGE_SIZE); + pte_val(*pt_dir) = __pa(page) | pgt_prot; + break; + case POPULATE_ZERO_SHADOW: + page = kasan_zero_page; + pte_val(*pt_dir) = __pa(page) | pgt_prot_zero; + break; + } + } + address += PAGE_SIZE; + } +} + +static void __init kasan_set_pgd(pgd_t *pgd, unsigned long asce_type) +{ + unsigned long asce_bits; + + asce_bits = asce_type | _ASCE_TABLE_LENGTH; + S390_lowcore.kernel_asce = (__pa(pgd) & PAGE_MASK) | asce_bits; + S390_lowcore.user_asce = S390_lowcore.kernel_asce; + + __ctl_load(S390_lowcore.kernel_asce, 1, 1); + __ctl_load(S390_lowcore.kernel_asce, 7, 7); + __ctl_load(S390_lowcore.kernel_asce, 13, 13); +} + +static void __init kasan_enable_dat(void) +{ + psw_t psw; + + psw.mask = __extract_psw(); + psw_bits(psw).dat = 1; + psw_bits(psw).as = PSW_BITS_AS_HOME; + __load_psw_mask(psw.mask); +} + +void __init kasan_early_init(void) +{ + unsigned long untracked_mem_end; + unsigned long shadow_alloc_size; + unsigned long initrd_end; + unsigned long asce_type; + unsigned long memsize; + unsigned long vmax; + unsigned long pgt_prot = pgprot_val(PAGE_KERNEL_RO); + pte_t pte_z; + pmd_t pmd_z = __pmd(__pa(kasan_zero_pte) | _SEGMENT_ENTRY); + pud_t pud_z = __pud(__pa(kasan_zero_pmd) | _REGION3_ENTRY); + p4d_t p4d_z = __p4d(__pa(kasan_zero_pud) | _REGION2_ENTRY); + + pgt_prot &= ~_PAGE_NOEXEC; + pte_z = __pte(__pa(kasan_zero_page) | pgt_prot); + + /* 3 level paging */ + BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PUD_SIZE)); + BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PUD_SIZE)); + crst_table_init((unsigned long *)early_pg_dir, _REGION3_ENTRY_EMPTY); + untracked_mem_end = vmax = _REGION2_SIZE; + asce_type = _ASCE_TYPE_REGION3; + + /* init kasan zero shadow */ + crst_table_init((unsigned long *)kasan_zero_p4d, p4d_val(p4d_z)); + crst_table_init((unsigned long *)kasan_zero_pud, pud_val(pud_z)); + crst_table_init((unsigned long *)kasan_zero_pmd, pmd_val(pmd_z)); + memset64((u64 *)kasan_zero_pte, pte_val(pte_z), PTRS_PER_PTE); + + memsize = min(max_physmem_end, KASAN_SHADOW_START); + shadow_alloc_size = memsize >> KASAN_SHADOW_SCALE_SHIFT; + if (IS_ENABLED(CONFIG_MODULES)) + shadow_alloc_size += MODULES_LEN >> KASAN_SHADOW_SCALE_SHIFT; + pgalloc_low = round_up((unsigned long)_end, _SEGMENT_SIZE); + if (IS_ENABLED(CONFIG_BLK_DEV_INITRD)) { + initrd_end = + round_up(INITRD_START + INITRD_SIZE, _SEGMENT_SIZE); + pgalloc_low = max(pgalloc_low, initrd_end); + } + + if (pgalloc_low + shadow_alloc_size > memsize) + kasan_early_panic("out of memory during initialisation\n"); + + pgalloc_pos = memsize; + init_mm.pgd = early_pg_dir; + /* + * Current memory layout: + * +- 0 -------------+ +- shadow start -+ + * | 1:1 ram mapping | /| 1/8 ram | + * +- end of ram ----+ / +----------------+ + * | ... gap ... |/ | kasan | + * +- shadow start --+ | zero | + * | 1/8 addr space | | page | + * +- shadow end -+ | mapping | + * | ... gap ... |\ | (untracked) | + * +- modules vaddr -+ \ +----------------+ + * | 2Gb | \| 256Mb | + * +-----------------+ +- shadow end ---+ + */ + /* populate identity mapping */ + kasan_early_vmemmap_populate(0, memsize, POPULATE_ONE2ONE); + /* populate kasan shadow (for identity mapping / modules / zero page) */ + kasan_early_vmemmap_populate(__sha(0), __sha(memsize), POPULATE_MAP); + if (IS_ENABLED(CONFIG_MODULES)) { + untracked_mem_end = vmax - MODULES_LEN; + kasan_early_vmemmap_populate(__sha(untracked_mem_end), + __sha(vmax), POPULATE_MAP); + } + kasan_early_vmemmap_populate(__sha(memsize), __sha(untracked_mem_end), + POPULATE_ZERO_SHADOW); + kasan_set_pgd(early_pg_dir, asce_type); + kasan_enable_dat(); + /* enable kasan */ + init_task.kasan_depth = 0; + memblock_reserve(pgalloc_pos, memsize - pgalloc_pos); + sclp_early_printk("KernelAddressSanitizer initialized\n"); +} + +void __init kasan_copy_shadow(pgd_t *pg_dir) +{ + /* + * At this point we are still running on early pages setup early_pg_dir, + * while swapper_pg_dir has just been initialized with identity mapping. + * Carry over shadow memory region from early_pg_dir to swapper_pg_dir. + */ + + pgd_t *pg_dir_src; + pgd_t *pg_dir_dst; + p4d_t *p4_dir_src; + p4d_t *p4_dir_dst; + pud_t *pu_dir_src; + pud_t *pu_dir_dst; + + pg_dir_src = pgd_offset_raw(early_pg_dir, KASAN_SHADOW_START); + pg_dir_dst = pgd_offset_raw(pg_dir, KASAN_SHADOW_START); + p4_dir_src = p4d_offset(pg_dir_src, KASAN_SHADOW_START); + p4_dir_dst = p4d_offset(pg_dir_dst, KASAN_SHADOW_START); + if (!p4d_folded(*p4_dir_src)) { + /* 4 level paging */ + memcpy(p4_dir_dst, p4_dir_src, + (KASAN_SHADOW_SIZE >> P4D_SHIFT) * sizeof(p4d_t)); + return; + } + /* 3 level paging */ + pu_dir_src = pud_offset(p4_dir_src, KASAN_SHADOW_START); + pu_dir_dst = pud_offset(p4_dir_dst, KASAN_SHADOW_START); + memcpy(pu_dir_dst, pu_dir_src, + (KASAN_SHADOW_SIZE >> PUD_SHIFT) * sizeof(pud_t)); +} -- GitLab