87 строки
1.9 KiB
C
87 строки
1.9 KiB
C
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/*
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* mpx.c - Memory Protection eXtensions
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*
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* Copyright (c) 2014, Intel Corporation.
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* Qiaowei Ren <qiaowei.ren@intel.com>
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* Dave Hansen <dave.hansen@intel.com>
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*/
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#include <linux/kernel.h>
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#include <linux/syscalls.h>
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#include <linux/sched/sysctl.h>
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#include <asm/mman.h>
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#include <asm/mpx.h>
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static const char *mpx_mapping_name(struct vm_area_struct *vma)
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{
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return "[mpx]";
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}
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static struct vm_operations_struct mpx_vma_ops = {
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.name = mpx_mapping_name,
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};
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/*
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* This is really a simplified "vm_mmap". it only handles MPX
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* bounds tables (the bounds directory is user-allocated).
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*
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* Later on, we use the vma->vm_ops to uniquely identify these
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* VMAs.
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*/
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static unsigned long mpx_mmap(unsigned long len)
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{
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unsigned long ret;
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unsigned long addr, pgoff;
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struct mm_struct *mm = current->mm;
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vm_flags_t vm_flags;
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struct vm_area_struct *vma;
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/* Only bounds table and bounds directory can be allocated here */
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if (len != MPX_BD_SIZE_BYTES && len != MPX_BT_SIZE_BYTES)
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return -EINVAL;
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down_write(&mm->mmap_sem);
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/* Too many mappings? */
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if (mm->map_count > sysctl_max_map_count) {
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ret = -ENOMEM;
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goto out;
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}
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/* Obtain the address to map to. we verify (or select) it and ensure
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* that it represents a valid section of the address space.
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*/
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addr = get_unmapped_area(NULL, 0, len, 0, MAP_ANONYMOUS | MAP_PRIVATE);
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if (addr & ~PAGE_MASK) {
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ret = addr;
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goto out;
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}
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vm_flags = VM_READ | VM_WRITE | VM_MPX |
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mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
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/* Set pgoff according to addr for anon_vma */
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pgoff = addr >> PAGE_SHIFT;
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ret = mmap_region(NULL, addr, len, vm_flags, pgoff);
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if (IS_ERR_VALUE(ret))
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goto out;
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vma = find_vma(mm, ret);
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if (!vma) {
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ret = -ENOMEM;
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goto out;
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}
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vma->vm_ops = &mpx_vma_ops;
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if (vm_flags & VM_LOCKED) {
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up_write(&mm->mmap_sem);
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mm_populate(ret, len);
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return ret;
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}
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out:
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up_write(&mm->mmap_sem);
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return ret;
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}
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