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