![Thomas Garnier](/assets/img/avatar_default.png)
KASLR memory randomization can randomize the base of the physical memory mapping (PAGE_OFFSET), vmalloc (VMALLOC_START) and vmemmap (VMEMMAP_START). Adding these variables on VMCOREINFO so tools can easily identify the base of each memory section. Link: http://lkml.kernel.org/r/1471531632-23003-1-git-send-email-thgarnie@google.com Signed-off-by: Thomas Garnier <thgarnie@google.com> Acked-by: Baoquan He <bhe@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Xunlei Pang <xlpang@redhat.com> Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> Cc: Kees Cook <keescook@chromium.org> Cc: Eugene Surovegin <surovegin@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
589 lines
14 KiB
C
589 lines
14 KiB
C
/*
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* handle transition of Linux booting another kernel
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* Copyright (C) 2002-2005 Eric Biederman <ebiederm@xmission.com>
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*
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* This source code is licensed under the GNU General Public License,
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* Version 2. See the file COPYING for more details.
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*/
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#define pr_fmt(fmt) "kexec: " fmt
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#include <linux/mm.h>
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#include <linux/kexec.h>
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#include <linux/string.h>
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#include <linux/gfp.h>
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#include <linux/reboot.h>
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#include <linux/numa.h>
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#include <linux/ftrace.h>
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#include <linux/io.h>
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#include <linux/suspend.h>
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#include <linux/vmalloc.h>
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#include <asm/init.h>
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#include <asm/pgtable.h>
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#include <asm/tlbflush.h>
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#include <asm/mmu_context.h>
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#include <asm/io_apic.h>
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#include <asm/debugreg.h>
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#include <asm/kexec-bzimage64.h>
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#include <asm/setup.h>
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#ifdef CONFIG_KEXEC_FILE
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static struct kexec_file_ops *kexec_file_loaders[] = {
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&kexec_bzImage64_ops,
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};
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#endif
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static void free_transition_pgtable(struct kimage *image)
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{
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free_page((unsigned long)image->arch.pud);
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free_page((unsigned long)image->arch.pmd);
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free_page((unsigned long)image->arch.pte);
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}
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static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
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{
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pud_t *pud;
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pmd_t *pmd;
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pte_t *pte;
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unsigned long vaddr, paddr;
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int result = -ENOMEM;
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vaddr = (unsigned long)relocate_kernel;
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paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE);
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pgd += pgd_index(vaddr);
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if (!pgd_present(*pgd)) {
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pud = (pud_t *)get_zeroed_page(GFP_KERNEL);
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if (!pud)
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goto err;
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image->arch.pud = pud;
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set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
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}
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pud = pud_offset(pgd, vaddr);
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if (!pud_present(*pud)) {
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pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
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if (!pmd)
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goto err;
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image->arch.pmd = pmd;
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set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
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}
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pmd = pmd_offset(pud, vaddr);
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if (!pmd_present(*pmd)) {
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pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
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if (!pte)
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goto err;
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image->arch.pte = pte;
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set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
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}
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pte = pte_offset_kernel(pmd, vaddr);
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set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
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return 0;
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err:
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free_transition_pgtable(image);
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return result;
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}
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static void *alloc_pgt_page(void *data)
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{
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struct kimage *image = (struct kimage *)data;
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struct page *page;
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void *p = NULL;
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page = kimage_alloc_control_pages(image, 0);
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if (page) {
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p = page_address(page);
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clear_page(p);
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}
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return p;
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}
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static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
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{
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struct x86_mapping_info info = {
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.alloc_pgt_page = alloc_pgt_page,
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.context = image,
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.pmd_flag = __PAGE_KERNEL_LARGE_EXEC,
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};
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unsigned long mstart, mend;
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pgd_t *level4p;
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int result;
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int i;
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level4p = (pgd_t *)__va(start_pgtable);
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clear_page(level4p);
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for (i = 0; i < nr_pfn_mapped; i++) {
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mstart = pfn_mapped[i].start << PAGE_SHIFT;
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mend = pfn_mapped[i].end << PAGE_SHIFT;
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result = kernel_ident_mapping_init(&info,
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level4p, mstart, mend);
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if (result)
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return result;
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}
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/*
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* segments's mem ranges could be outside 0 ~ max_pfn,
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* for example when jump back to original kernel from kexeced kernel.
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* or first kernel is booted with user mem map, and second kernel
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* could be loaded out of that range.
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*/
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for (i = 0; i < image->nr_segments; i++) {
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mstart = image->segment[i].mem;
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mend = mstart + image->segment[i].memsz;
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result = kernel_ident_mapping_init(&info,
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level4p, mstart, mend);
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if (result)
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return result;
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}
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return init_transition_pgtable(image, level4p);
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}
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static void set_idt(void *newidt, u16 limit)
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{
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struct desc_ptr curidt;
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/* x86-64 supports unaliged loads & stores */
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curidt.size = limit;
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curidt.address = (unsigned long)newidt;
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__asm__ __volatile__ (
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"lidtq %0\n"
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: : "m" (curidt)
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);
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};
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static void set_gdt(void *newgdt, u16 limit)
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{
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struct desc_ptr curgdt;
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/* x86-64 supports unaligned loads & stores */
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curgdt.size = limit;
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curgdt.address = (unsigned long)newgdt;
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__asm__ __volatile__ (
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"lgdtq %0\n"
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: : "m" (curgdt)
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);
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};
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static void load_segments(void)
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{
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__asm__ __volatile__ (
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"\tmovl %0,%%ds\n"
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"\tmovl %0,%%es\n"
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"\tmovl %0,%%ss\n"
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"\tmovl %0,%%fs\n"
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"\tmovl %0,%%gs\n"
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: : "a" (__KERNEL_DS) : "memory"
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);
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}
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#ifdef CONFIG_KEXEC_FILE
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/* Update purgatory as needed after various image segments have been prepared */
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static int arch_update_purgatory(struct kimage *image)
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{
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int ret = 0;
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if (!image->file_mode)
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return 0;
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/* Setup copying of backup region */
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if (image->type == KEXEC_TYPE_CRASH) {
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ret = kexec_purgatory_get_set_symbol(image, "backup_dest",
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&image->arch.backup_load_addr,
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sizeof(image->arch.backup_load_addr), 0);
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if (ret)
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return ret;
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ret = kexec_purgatory_get_set_symbol(image, "backup_src",
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&image->arch.backup_src_start,
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sizeof(image->arch.backup_src_start), 0);
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if (ret)
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return ret;
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ret = kexec_purgatory_get_set_symbol(image, "backup_sz",
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&image->arch.backup_src_sz,
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sizeof(image->arch.backup_src_sz), 0);
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if (ret)
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return ret;
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}
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return ret;
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}
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#else /* !CONFIG_KEXEC_FILE */
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static inline int arch_update_purgatory(struct kimage *image)
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{
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return 0;
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}
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#endif /* CONFIG_KEXEC_FILE */
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int machine_kexec_prepare(struct kimage *image)
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{
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unsigned long start_pgtable;
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int result;
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/* Calculate the offsets */
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start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
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/* Setup the identity mapped 64bit page table */
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result = init_pgtable(image, start_pgtable);
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if (result)
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return result;
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/* update purgatory as needed */
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result = arch_update_purgatory(image);
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if (result)
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return result;
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return 0;
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}
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void machine_kexec_cleanup(struct kimage *image)
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{
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free_transition_pgtable(image);
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}
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/*
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* Do not allocate memory (or fail in any way) in machine_kexec().
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* We are past the point of no return, committed to rebooting now.
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*/
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void machine_kexec(struct kimage *image)
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{
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unsigned long page_list[PAGES_NR];
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void *control_page;
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int save_ftrace_enabled;
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#ifdef CONFIG_KEXEC_JUMP
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if (image->preserve_context)
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save_processor_state();
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#endif
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save_ftrace_enabled = __ftrace_enabled_save();
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/* Interrupts aren't acceptable while we reboot */
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local_irq_disable();
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hw_breakpoint_disable();
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if (image->preserve_context) {
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#ifdef CONFIG_X86_IO_APIC
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/*
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* We need to put APICs in legacy mode so that we can
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* get timer interrupts in second kernel. kexec/kdump
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* paths already have calls to disable_IO_APIC() in
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* one form or other. kexec jump path also need
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* one.
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*/
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disable_IO_APIC();
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#endif
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}
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control_page = page_address(image->control_code_page) + PAGE_SIZE;
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memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
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page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
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page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
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page_list[PA_TABLE_PAGE] =
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(unsigned long)__pa(page_address(image->control_code_page));
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if (image->type == KEXEC_TYPE_DEFAULT)
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page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
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<< PAGE_SHIFT);
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/*
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* The segment registers are funny things, they have both a
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* visible and an invisible part. Whenever the visible part is
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* set to a specific selector, the invisible part is loaded
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* with from a table in memory. At no other time is the
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* descriptor table in memory accessed.
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*
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* I take advantage of this here by force loading the
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* segments, before I zap the gdt with an invalid value.
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*/
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load_segments();
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/*
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* The gdt & idt are now invalid.
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* If you want to load them you must set up your own idt & gdt.
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*/
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set_gdt(phys_to_virt(0), 0);
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set_idt(phys_to_virt(0), 0);
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/* now call it */
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image->start = relocate_kernel((unsigned long)image->head,
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(unsigned long)page_list,
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image->start,
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image->preserve_context);
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#ifdef CONFIG_KEXEC_JUMP
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if (image->preserve_context)
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restore_processor_state();
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#endif
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__ftrace_enabled_restore(save_ftrace_enabled);
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}
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void arch_crash_save_vmcoreinfo(void)
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{
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VMCOREINFO_SYMBOL(phys_base);
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VMCOREINFO_SYMBOL(init_level4_pgt);
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#ifdef CONFIG_NUMA
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VMCOREINFO_SYMBOL(node_data);
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VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
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#endif
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vmcoreinfo_append_str("KERNELOFFSET=%lx\n",
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kaslr_offset());
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VMCOREINFO_PAGE_OFFSET(PAGE_OFFSET);
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VMCOREINFO_VMALLOC_START(VMALLOC_START);
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VMCOREINFO_VMEMMAP_START(VMEMMAP_START);
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}
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/* arch-dependent functionality related to kexec file-based syscall */
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#ifdef CONFIG_KEXEC_FILE
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int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
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unsigned long buf_len)
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{
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int i, ret = -ENOEXEC;
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struct kexec_file_ops *fops;
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for (i = 0; i < ARRAY_SIZE(kexec_file_loaders); i++) {
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fops = kexec_file_loaders[i];
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if (!fops || !fops->probe)
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continue;
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ret = fops->probe(buf, buf_len);
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if (!ret) {
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image->fops = fops;
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return ret;
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}
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}
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return ret;
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}
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void *arch_kexec_kernel_image_load(struct kimage *image)
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{
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vfree(image->arch.elf_headers);
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image->arch.elf_headers = NULL;
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if (!image->fops || !image->fops->load)
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return ERR_PTR(-ENOEXEC);
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return image->fops->load(image, image->kernel_buf,
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image->kernel_buf_len, image->initrd_buf,
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image->initrd_buf_len, image->cmdline_buf,
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image->cmdline_buf_len);
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}
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int arch_kimage_file_post_load_cleanup(struct kimage *image)
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{
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if (!image->fops || !image->fops->cleanup)
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return 0;
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return image->fops->cleanup(image->image_loader_data);
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}
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#ifdef CONFIG_KEXEC_VERIFY_SIG
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int arch_kexec_kernel_verify_sig(struct kimage *image, void *kernel,
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unsigned long kernel_len)
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{
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if (!image->fops || !image->fops->verify_sig) {
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pr_debug("kernel loader does not support signature verification.");
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return -EKEYREJECTED;
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}
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return image->fops->verify_sig(kernel, kernel_len);
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}
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#endif
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/*
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* Apply purgatory relocations.
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*
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* ehdr: Pointer to elf headers
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* sechdrs: Pointer to section headers.
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* relsec: section index of SHT_RELA section.
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*
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* TODO: Some of the code belongs to generic code. Move that in kexec.c.
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*/
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int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
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Elf64_Shdr *sechdrs, unsigned int relsec)
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{
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unsigned int i;
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Elf64_Rela *rel;
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Elf64_Sym *sym;
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void *location;
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Elf64_Shdr *section, *symtabsec;
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unsigned long address, sec_base, value;
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const char *strtab, *name, *shstrtab;
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/*
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* ->sh_offset has been modified to keep the pointer to section
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* contents in memory
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*/
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rel = (void *)sechdrs[relsec].sh_offset;
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/* Section to which relocations apply */
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section = &sechdrs[sechdrs[relsec].sh_info];
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pr_debug("Applying relocate section %u to %u\n", relsec,
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sechdrs[relsec].sh_info);
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/* Associated symbol table */
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symtabsec = &sechdrs[sechdrs[relsec].sh_link];
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/* String table */
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if (symtabsec->sh_link >= ehdr->e_shnum) {
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/* Invalid strtab section number */
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pr_err("Invalid string table section index %d\n",
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symtabsec->sh_link);
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return -ENOEXEC;
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}
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strtab = (char *)sechdrs[symtabsec->sh_link].sh_offset;
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/* section header string table */
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shstrtab = (char *)sechdrs[ehdr->e_shstrndx].sh_offset;
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for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
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/*
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* rel[i].r_offset contains byte offset from beginning
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* of section to the storage unit affected.
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*
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* This is location to update (->sh_offset). This is temporary
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* buffer where section is currently loaded. This will finally
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* be loaded to a different address later, pointed to by
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* ->sh_addr. kexec takes care of moving it
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* (kexec_load_segment()).
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*/
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location = (void *)(section->sh_offset + rel[i].r_offset);
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/* Final address of the location */
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address = section->sh_addr + rel[i].r_offset;
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/*
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* rel[i].r_info contains information about symbol table index
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* w.r.t which relocation must be made and type of relocation
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* to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get
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* these respectively.
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*/
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sym = (Elf64_Sym *)symtabsec->sh_offset +
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ELF64_R_SYM(rel[i].r_info);
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if (sym->st_name)
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name = strtab + sym->st_name;
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else
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name = shstrtab + sechdrs[sym->st_shndx].sh_name;
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pr_debug("Symbol: %s info: %02x shndx: %02x value=%llx size: %llx\n",
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name, sym->st_info, sym->st_shndx, sym->st_value,
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sym->st_size);
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if (sym->st_shndx == SHN_UNDEF) {
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pr_err("Undefined symbol: %s\n", name);
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return -ENOEXEC;
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}
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if (sym->st_shndx == SHN_COMMON) {
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pr_err("symbol '%s' in common section\n", name);
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return -ENOEXEC;
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}
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if (sym->st_shndx == SHN_ABS)
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sec_base = 0;
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else if (sym->st_shndx >= ehdr->e_shnum) {
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pr_err("Invalid section %d for symbol %s\n",
|
|
sym->st_shndx, name);
|
|
return -ENOEXEC;
|
|
} else
|
|
sec_base = sechdrs[sym->st_shndx].sh_addr;
|
|
|
|
value = sym->st_value;
|
|
value += sec_base;
|
|
value += rel[i].r_addend;
|
|
|
|
switch (ELF64_R_TYPE(rel[i].r_info)) {
|
|
case R_X86_64_NONE:
|
|
break;
|
|
case R_X86_64_64:
|
|
*(u64 *)location = value;
|
|
break;
|
|
case R_X86_64_32:
|
|
*(u32 *)location = value;
|
|
if (value != *(u32 *)location)
|
|
goto overflow;
|
|
break;
|
|
case R_X86_64_32S:
|
|
*(s32 *)location = value;
|
|
if ((s64)value != *(s32 *)location)
|
|
goto overflow;
|
|
break;
|
|
case R_X86_64_PC32:
|
|
value -= (u64)address;
|
|
*(u32 *)location = value;
|
|
break;
|
|
default:
|
|
pr_err("Unknown rela relocation: %llu\n",
|
|
ELF64_R_TYPE(rel[i].r_info));
|
|
return -ENOEXEC;
|
|
}
|
|
}
|
|
return 0;
|
|
|
|
overflow:
|
|
pr_err("Overflow in relocation type %d value 0x%lx\n",
|
|
(int)ELF64_R_TYPE(rel[i].r_info), value);
|
|
return -ENOEXEC;
|
|
}
|
|
#endif /* CONFIG_KEXEC_FILE */
|
|
|
|
static int
|
|
kexec_mark_range(unsigned long start, unsigned long end, bool protect)
|
|
{
|
|
struct page *page;
|
|
unsigned int nr_pages;
|
|
|
|
/*
|
|
* For physical range: [start, end]. We must skip the unassigned
|
|
* crashk resource with zero-valued "end" member.
|
|
*/
|
|
if (!end || start > end)
|
|
return 0;
|
|
|
|
page = pfn_to_page(start >> PAGE_SHIFT);
|
|
nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
|
|
if (protect)
|
|
return set_pages_ro(page, nr_pages);
|
|
else
|
|
return set_pages_rw(page, nr_pages);
|
|
}
|
|
|
|
static void kexec_mark_crashkres(bool protect)
|
|
{
|
|
unsigned long control;
|
|
|
|
kexec_mark_range(crashk_low_res.start, crashk_low_res.end, protect);
|
|
|
|
/* Don't touch the control code page used in crash_kexec().*/
|
|
control = PFN_PHYS(page_to_pfn(kexec_crash_image->control_code_page));
|
|
/* Control code page is located in the 2nd page. */
|
|
kexec_mark_range(crashk_res.start, control + PAGE_SIZE - 1, protect);
|
|
control += KEXEC_CONTROL_PAGE_SIZE;
|
|
kexec_mark_range(control, crashk_res.end, protect);
|
|
}
|
|
|
|
void arch_kexec_protect_crashkres(void)
|
|
{
|
|
kexec_mark_crashkres(true);
|
|
}
|
|
|
|
void arch_kexec_unprotect_crashkres(void)
|
|
{
|
|
kexec_mark_crashkres(false);
|
|
}
|