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150 lines
3.2 KiB
150 lines
3.2 KiB
/*
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* arch/sh/kernel/vsyscall.c
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*
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* Copyright (C) 2006 Paul Mundt
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*
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* vDSO randomization
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* Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/gfp.h>
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#include <linux/module.h>
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#include <linux/elf.h>
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/*
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* Should the kernel map a VDSO page into processes and pass its
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* address down to glibc upon exec()?
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*/
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unsigned int __read_mostly vdso_enabled = 1;
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EXPORT_SYMBOL_GPL(vdso_enabled);
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static int __init vdso_setup(char *s)
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{
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vdso_enabled = simple_strtoul(s, NULL, 0);
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return 1;
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}
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__setup("vdso=", vdso_setup);
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/*
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* These symbols are defined by vsyscall.o to mark the bounds
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* of the ELF DSO images included therein.
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*/
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extern const char vsyscall_trapa_start, vsyscall_trapa_end;
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static void *syscall_page;
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int __init vsyscall_init(void)
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{
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syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
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/*
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* XXX: Map this page to a fixmap entry if we get around
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* to adding the page to ELF core dumps
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*/
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memcpy(syscall_page,
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&vsyscall_trapa_start,
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&vsyscall_trapa_end - &vsyscall_trapa_start);
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return 0;
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}
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static struct page *syscall_vma_nopage(struct vm_area_struct *vma,
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unsigned long address, int *type)
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{
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unsigned long offset = address - vma->vm_start;
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struct page *page;
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if (address < vma->vm_start || address > vma->vm_end)
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return NOPAGE_SIGBUS;
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page = virt_to_page(syscall_page + offset);
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get_page(page);
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return page;
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}
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/* Prevent VMA merging */
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static void syscall_vma_close(struct vm_area_struct *vma)
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{
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}
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static struct vm_operations_struct syscall_vm_ops = {
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.nopage = syscall_vma_nopage,
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.close = syscall_vma_close,
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};
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/* Setup a VMA at program startup for the vsyscall page */
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int arch_setup_additional_pages(struct linux_binprm *bprm,
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int executable_stack)
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{
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struct vm_area_struct *vma;
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struct mm_struct *mm = current->mm;
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unsigned long addr;
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int ret;
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down_write(&mm->mmap_sem);
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addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
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if (IS_ERR_VALUE(addr)) {
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ret = addr;
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goto up_fail;
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}
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vma = kmem_cache_zalloc(vm_area_cachep, SLAB_KERNEL);
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if (!vma) {
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ret = -ENOMEM;
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goto up_fail;
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}
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vma->vm_start = addr;
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vma->vm_end = addr + PAGE_SIZE;
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/* MAYWRITE to allow gdb to COW and set breakpoints */
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vma->vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC|VM_MAYWRITE;
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vma->vm_flags |= mm->def_flags;
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vma->vm_page_prot = protection_map[vma->vm_flags & 7];
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vma->vm_ops = &syscall_vm_ops;
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vma->vm_mm = mm;
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ret = insert_vm_struct(mm, vma);
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if (unlikely(ret)) {
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kmem_cache_free(vm_area_cachep, vma);
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goto up_fail;
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}
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current->mm->context.vdso = (void *)addr;
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mm->total_vm++;
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up_fail:
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up_write(&mm->mmap_sem);
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return ret;
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}
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const char *arch_vma_name(struct vm_area_struct *vma)
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{
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if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
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return "[vdso]";
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return NULL;
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}
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struct vm_area_struct *get_gate_vma(struct task_struct *task)
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{
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return NULL;
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}
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int in_gate_area(struct task_struct *task, unsigned long address)
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{
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return 0;
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}
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int in_gate_area_no_task(unsigned long address)
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{
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return 0;
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}
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