blob: 1bbf4335de4540598528240e6106896b8d6d5c4a [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0-only
/*
* Set up the VMAs to tell the VM about the vDSO.
* Copyright 2007 Andi Kleen, SUSE Labs.
*/
/*
* Copyright (c) 2017 Oracle and/or its affiliates. All rights reserved.
*/
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/linkage.h>
#include <linux/random.h>
#include <linux/elf.h>
#include <asm/cacheflush.h>
#include <asm/spitfire.h>
#include <asm/vdso.h>
#include <asm/vvar.h>
#include <asm/page.h>
unsigned int __read_mostly vdso_enabled = 1;
static struct vm_special_mapping vvar_mapping = {
.name = "[vvar]"
};
#ifdef CONFIG_SPARC64
static struct vm_special_mapping vdso_mapping64 = {
.name = "[vdso]"
};
#endif
#ifdef CONFIG_COMPAT
static struct vm_special_mapping vdso_mapping32 = {
.name = "[vdso]"
};
#endif
struct vvar_data *vvar_data;
struct vdso_elfinfo32 {
Elf32_Ehdr *hdr;
Elf32_Sym *dynsym;
unsigned long dynsymsize;
const char *dynstr;
unsigned long text;
};
struct vdso_elfinfo64 {
Elf64_Ehdr *hdr;
Elf64_Sym *dynsym;
unsigned long dynsymsize;
const char *dynstr;
unsigned long text;
};
struct vdso_elfinfo {
union {
struct vdso_elfinfo32 elf32;
struct vdso_elfinfo64 elf64;
} u;
};
static void *one_section64(struct vdso_elfinfo64 *e, const char *name,
unsigned long *size)
{
const char *snames;
Elf64_Shdr *shdrs;
unsigned int i;
shdrs = (void *)e->hdr + e->hdr->e_shoff;
snames = (void *)e->hdr + shdrs[e->hdr->e_shstrndx].sh_offset;
for (i = 1; i < e->hdr->e_shnum; i++) {
if (!strcmp(snames+shdrs[i].sh_name, name)) {
if (size)
*size = shdrs[i].sh_size;
return (void *)e->hdr + shdrs[i].sh_offset;
}
}
return NULL;
}
static int find_sections64(const struct vdso_image *image, struct vdso_elfinfo *_e)
{
struct vdso_elfinfo64 *e = &_e->u.elf64;
e->hdr = image->data;
e->dynsym = one_section64(e, ".dynsym", &e->dynsymsize);
e->dynstr = one_section64(e, ".dynstr", NULL);
if (!e->dynsym || !e->dynstr) {
pr_err("VDSO64: Missing symbol sections.\n");
return -ENODEV;
}
return 0;
}
static Elf64_Sym *find_sym64(const struct vdso_elfinfo64 *e, const char *name)
{
unsigned int i;
for (i = 0; i < (e->dynsymsize / sizeof(Elf64_Sym)); i++) {
Elf64_Sym *s = &e->dynsym[i];
if (s->st_name == 0)
continue;
if (!strcmp(e->dynstr + s->st_name, name))
return s;
}
return NULL;
}
static int patchsym64(struct vdso_elfinfo *_e, const char *orig,
const char *new)
{
struct vdso_elfinfo64 *e = &_e->u.elf64;
Elf64_Sym *osym = find_sym64(e, orig);
Elf64_Sym *nsym = find_sym64(e, new);
if (!nsym || !osym) {
pr_err("VDSO64: Missing symbols.\n");
return -ENODEV;
}
osym->st_value = nsym->st_value;
osym->st_size = nsym->st_size;
osym->st_info = nsym->st_info;
osym->st_other = nsym->st_other;
osym->st_shndx = nsym->st_shndx;
return 0;
}
static void *one_section32(struct vdso_elfinfo32 *e, const char *name,
unsigned long *size)
{
const char *snames;
Elf32_Shdr *shdrs;
unsigned int i;
shdrs = (void *)e->hdr + e->hdr->e_shoff;
snames = (void *)e->hdr + shdrs[e->hdr->e_shstrndx].sh_offset;
for (i = 1; i < e->hdr->e_shnum; i++) {
if (!strcmp(snames+shdrs[i].sh_name, name)) {
if (size)
*size = shdrs[i].sh_size;
return (void *)e->hdr + shdrs[i].sh_offset;
}
}
return NULL;
}
static int find_sections32(const struct vdso_image *image, struct vdso_elfinfo *_e)
{
struct vdso_elfinfo32 *e = &_e->u.elf32;
e->hdr = image->data;
e->dynsym = one_section32(e, ".dynsym", &e->dynsymsize);
e->dynstr = one_section32(e, ".dynstr", NULL);
if (!e->dynsym || !e->dynstr) {
pr_err("VDSO32: Missing symbol sections.\n");
return -ENODEV;
}
return 0;
}
static Elf32_Sym *find_sym32(const struct vdso_elfinfo32 *e, const char *name)
{
unsigned int i;
for (i = 0; i < (e->dynsymsize / sizeof(Elf32_Sym)); i++) {
Elf32_Sym *s = &e->dynsym[i];
if (s->st_name == 0)
continue;
if (!strcmp(e->dynstr + s->st_name, name))
return s;
}
return NULL;
}
static int patchsym32(struct vdso_elfinfo *_e, const char *orig,
const char *new)
{
struct vdso_elfinfo32 *e = &_e->u.elf32;
Elf32_Sym *osym = find_sym32(e, orig);
Elf32_Sym *nsym = find_sym32(e, new);
if (!nsym || !osym) {
pr_err("VDSO32: Missing symbols.\n");
return -ENODEV;
}
osym->st_value = nsym->st_value;
osym->st_size = nsym->st_size;
osym->st_info = nsym->st_info;
osym->st_other = nsym->st_other;
osym->st_shndx = nsym->st_shndx;
return 0;
}
static int find_sections(const struct vdso_image *image, struct vdso_elfinfo *e,
bool elf64)
{
if (elf64)
return find_sections64(image, e);
else
return find_sections32(image, e);
}
static int patch_one_symbol(struct vdso_elfinfo *e, const char *orig,
const char *new_target, bool elf64)
{
if (elf64)
return patchsym64(e, orig, new_target);
else
return patchsym32(e, orig, new_target);
}
static int stick_patch(const struct vdso_image *image, struct vdso_elfinfo *e, bool elf64)
{
int err;
err = find_sections(image, e, elf64);
if (err)
return err;
err = patch_one_symbol(e,
"__vdso_gettimeofday",
"__vdso_gettimeofday_stick", elf64);
if (err)
return err;
return patch_one_symbol(e,
"__vdso_clock_gettime",
"__vdso_clock_gettime_stick", elf64);
return 0;
}
/*
* Allocate pages for the vdso and vvar, and copy in the vdso text from the
* kernel image.
*/
int __init init_vdso_image(const struct vdso_image *image,
struct vm_special_mapping *vdso_mapping, bool elf64)
{
int cnpages = (image->size) / PAGE_SIZE;
struct page *dp, **dpp = NULL;
struct page *cp, **cpp = NULL;
struct vdso_elfinfo ei;
int i, dnpages = 0;
if (tlb_type != spitfire) {
int err = stick_patch(image, &ei, elf64);
if (err)
return err;
}
/*
* First, the vdso text. This is initialied data, an integral number of
* pages long.
*/
if (WARN_ON(image->size % PAGE_SIZE != 0))
goto oom;
cpp = kcalloc(cnpages, sizeof(struct page *), GFP_KERNEL);
vdso_mapping->pages = cpp;
if (!cpp)
goto oom;
for (i = 0; i < cnpages; i++) {
cp = alloc_page(GFP_KERNEL);
if (!cp)
goto oom;
cpp[i] = cp;
copy_page(page_address(cp), image->data + i * PAGE_SIZE);
}
/*
* Now the vvar page. This is uninitialized data.
*/
if (vvar_data == NULL) {
dnpages = (sizeof(struct vvar_data) / PAGE_SIZE) + 1;
if (WARN_ON(dnpages != 1))
goto oom;
dpp = kcalloc(dnpages, sizeof(struct page *), GFP_KERNEL);
vvar_mapping.pages = dpp;
if (!dpp)
goto oom;
dp = alloc_page(GFP_KERNEL);
if (!dp)
goto oom;
dpp[0] = dp;
vvar_data = page_address(dp);
memset(vvar_data, 0, PAGE_SIZE);
vvar_data->seq = 0;
}
return 0;
oom:
if (cpp != NULL) {
for (i = 0; i < cnpages; i++) {
if (cpp[i] != NULL)
__free_page(cpp[i]);
}
kfree(cpp);
vdso_mapping->pages = NULL;
}
if (dpp != NULL) {
for (i = 0; i < dnpages; i++) {
if (dpp[i] != NULL)
__free_page(dpp[i]);
}
kfree(dpp);
vvar_mapping.pages = NULL;
}
pr_warn("Cannot allocate vdso\n");
vdso_enabled = 0;
return -ENOMEM;
}
static int __init init_vdso(void)
{
int err = 0;
#ifdef CONFIG_SPARC64
err = init_vdso_image(&vdso_image_64_builtin, &vdso_mapping64, true);
if (err)
return err;
#endif
#ifdef CONFIG_COMPAT
err = init_vdso_image(&vdso_image_32_builtin, &vdso_mapping32, false);
#endif
return err;
}
subsys_initcall(init_vdso);
struct linux_binprm;
/* Shuffle the vdso up a bit, randomly. */
static unsigned long vdso_addr(unsigned long start, unsigned int len)
{
unsigned int offset;
/* This loses some more bits than a modulo, but is cheaper */
offset = get_random_u32_below(PTRS_PER_PTE);
return start + (offset << PAGE_SHIFT);
}
static int map_vdso(const struct vdso_image *image,
struct vm_special_mapping *vdso_mapping)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned long text_start, addr = 0;
int ret = 0;
mmap_write_lock(mm);
/*
* First, get an unmapped region: then randomize it, and make sure that
* region is free.
*/
if (current->flags & PF_RANDOMIZE) {
addr = get_unmapped_area(NULL, 0,
image->size - image->sym_vvar_start,
0, 0);
if (IS_ERR_VALUE(addr)) {
ret = addr;
goto up_fail;
}
addr = vdso_addr(addr, image->size - image->sym_vvar_start);
}
addr = get_unmapped_area(NULL, addr,
image->size - image->sym_vvar_start, 0, 0);
if (IS_ERR_VALUE(addr)) {
ret = addr;
goto up_fail;
}
text_start = addr - image->sym_vvar_start;
current->mm->context.vdso = (void __user *)text_start;
/*
* MAYWRITE to allow gdb to COW and set breakpoints
*/
vma = _install_special_mapping(mm,
text_start,
image->size,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
vdso_mapping);
if (IS_ERR(vma)) {
ret = PTR_ERR(vma);
goto up_fail;
}
vma = _install_special_mapping(mm,
addr,
-image->sym_vvar_start,
VM_READ|VM_MAYREAD,
&vvar_mapping);
if (IS_ERR(vma)) {
ret = PTR_ERR(vma);
do_munmap(mm, text_start, image->size, NULL);
}
up_fail:
if (ret)
current->mm->context.vdso = NULL;
mmap_write_unlock(mm);
return ret;
}
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
if (!vdso_enabled)
return 0;
#if defined CONFIG_COMPAT
if (!(is_32bit_task()))
return map_vdso(&vdso_image_64_builtin, &vdso_mapping64);
else
return map_vdso(&vdso_image_32_builtin, &vdso_mapping32);
#else
return map_vdso(&vdso_image_64_builtin, &vdso_mapping64);
#endif
}
static __init int vdso_setup(char *s)
{
int err;
unsigned long val;
err = kstrtoul(s, 10, &val);
if (!err)
vdso_enabled = val;
return 1;
}
__setup("vdso=", vdso_setup);