Quelle  vdso.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp.
 *                    <benh@kernel.crashing.org>
 * Copyright (C) 2012 ARM Limited
 * Copyright (C) 2015 Regents of the University of California
 */

#include <linux/elf.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/binfmts.h>
#include <linux/err.h>
#include <asm/page.h>
#include <asm/vdso.h>
#include <linux/vdso_datastore.h>
#include <vdso/datapage.h>
#include <vdso/vsyscall.h>

#define VVAR_SIZE  (VDSO_NR_PAGES << PAGE_SHIFT)

struct __vdso_info {
 const char *name;
 const char *vdso_code_start;
 const char *vdso_code_end;
 unsigned long vdso_pages;
 /* Code Mapping */
 struct vm_special_mapping *cm;
};

static struct __vdso_info vdso_info;
#ifdef CONFIG_COMPAT
static struct __vdso_info compat_vdso_info;
#endif

static int vdso_mremap(const struct vm_special_mapping *sm,
         struct vm_area_struct *new_vma)
{
 current->mm->context.vdso = (void *)new_vma->vm_start;

 return 0;
}

static void __init __vdso_init(struct __vdso_info *vdso_info)
{
 unsigned int i;
 struct page **vdso_pagelist;
 unsigned long pfn;

 if (memcmp(vdso_info->vdso_code_start, "\177ELF", 4))
  panic("vDSO is not a valid ELF object!\n");

 vdso_info->vdso_pages = (
  vdso_info->vdso_code_end -
  vdso_info->vdso_code_start) >>
  PAGE_SHIFT;

 vdso_pagelist = kcalloc(vdso_info->vdso_pages,
    sizeof(struct page *),
    GFP_KERNEL);
 if (vdso_pagelist == NULL)
  panic("vDSO kcalloc failed!\n");

 /* Grab the vDSO code pages. */
 pfn = sym_to_pfn(vdso_info->vdso_code_start);

 for (i = 0; i < vdso_info->vdso_pages; i++)
  vdso_pagelist[i] = pfn_to_page(pfn + i);

 vdso_info->cm->pages = vdso_pagelist;
}

static struct vm_special_mapping rv_vdso_map __ro_after_init = {
 .name   = "[vdso]",
 .mremap = vdso_mremap,
};

static struct __vdso_info vdso_info __ro_after_init = {
 .name = "vdso",
 .vdso_code_start = vdso_start,
 .vdso_code_end = vdso_end,
 .cm = &rv_vdso_map,
};

#ifdef CONFIG_COMPAT
static struct vm_special_mapping rv_compat_vdso_map __ro_after_init = {
 .name   = "[vdso]",
 .mremap = vdso_mremap,
};

static struct __vdso_info compat_vdso_info __ro_after_init = {
 .name = "compat_vdso",
 .vdso_code_start = compat_vdso_start,
 .vdso_code_end = compat_vdso_end,
 .cm = &rv_compat_vdso_map,
};
#endif

static int __init vdso_init(void)
{
 __vdso_init(&vdso_info);
#ifdef CONFIG_COMPAT
 __vdso_init(&compat_vdso_info);
#endif

 return 0;
}
arch_initcall(vdso_init);

static int __setup_additional_pages(struct mm_struct *mm,
        struct linux_binprm *bprm,
        int uses_interp,
        struct __vdso_info *vdso_info)
{
 unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
 void *ret;

 BUILD_BUG_ON(VDSO_NR_PAGES != __VDSO_PAGES);

 vdso_text_len = vdso_info->vdso_pages << PAGE_SHIFT;
 /* Be sure to map the data page */
 vdso_mapping_len = vdso_text_len + VVAR_SIZE;

 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
 if (IS_ERR_VALUE(vdso_base)) {
  ret = ERR_PTR(vdso_base);
  goto up_fail;
 }

 ret = vdso_install_vvar_mapping(mm, vdso_base);
 if (IS_ERR(ret))
  goto up_fail;

 vdso_base += VVAR_SIZE;
 mm->context.vdso = (void *)vdso_base;

 ret =
    _install_special_mapping(mm, vdso_base, vdso_text_len,
  (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC | VM_SEALED_SYSMAP),
  vdso_info->cm);

 if (IS_ERR(ret))
  goto up_fail;

 return 0;

up_fail:
 mm->context.vdso = NULL;
 return PTR_ERR(ret);
}

#ifdef CONFIG_COMPAT
int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
           int uses_interp)
{
 struct mm_struct *mm = current->mm;
 int ret;

 if (mmap_write_lock_killable(mm))
  return -EINTR;

 ret = __setup_additional_pages(mm, bprm, uses_interp,
       &compat_vdso_info);
 mmap_write_unlock(mm);

 return ret;
}
#endif

int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
 struct mm_struct *mm = current->mm;
 int ret;

 if (mmap_write_lock_killable(mm))
  return -EINTR;

 ret = __setup_additional_pages(mm, bprm, uses_interp, &vdso_info);
 mmap_write_unlock(mm);

 return ret;
}