| Current Path : /usr/src/libexec/rtld-elf/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
| Current File : //usr/src/libexec/rtld-elf/map_object.c |
/*-
* Copyright 1996-1998 John D. Polstra.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $FreeBSD: release/9.1.0/libexec/rtld-elf/map_object.c 239434 2012-08-20 15:05:29Z kan $
*/
#include <sys/param.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <errno.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "debug.h"
#include "rtld.h"
static Elf_Ehdr *get_elf_header(int, const char *);
static int convert_prot(int); /* Elf flags -> mmap protection */
static int convert_flags(int); /* Elf flags -> mmap flags */
/*
* Map a shared object into memory. The "fd" argument is a file descriptor,
* which must be open on the object and positioned at its beginning.
* The "path" argument is a pathname that is used only for error messages.
*
* The return value is a pointer to a newly-allocated Obj_Entry structure
* for the shared object. Returns NULL on failure.
*/
Obj_Entry *
map_object(int fd, const char *path, const struct stat *sb)
{
Obj_Entry *obj;
Elf_Ehdr *hdr;
int i;
Elf_Phdr *phdr;
Elf_Phdr *phlimit;
Elf_Phdr **segs;
int nsegs;
Elf_Phdr *phdyn;
Elf_Phdr *phinterp;
Elf_Phdr *phtls;
caddr_t mapbase;
size_t mapsize;
Elf_Addr base_vaddr;
Elf_Addr base_vlimit;
caddr_t base_addr;
Elf_Off data_offset;
Elf_Addr data_vaddr;
Elf_Addr data_vlimit;
caddr_t data_addr;
int data_prot;
int data_flags;
Elf_Addr clear_vaddr;
caddr_t clear_addr;
caddr_t clear_page;
Elf_Addr phdr_vaddr;
size_t nclear, phsize;
Elf_Addr bss_vaddr;
Elf_Addr bss_vlimit;
caddr_t bss_addr;
Elf_Word stack_flags;
Elf_Addr relro_page;
size_t relro_size;
Elf_Addr note_start;
Elf_Addr note_end;
hdr = get_elf_header(fd, path);
if (hdr == NULL)
return (NULL);
/*
* Scan the program header entries, and save key information.
*
* We expect that the loadable segments are ordered by load address.
*/
phdr = (Elf_Phdr *) ((char *)hdr + hdr->e_phoff);
phsize = hdr->e_phnum * sizeof (phdr[0]);
phlimit = phdr + hdr->e_phnum;
nsegs = -1;
phdyn = phinterp = phtls = NULL;
phdr_vaddr = 0;
relro_page = 0;
relro_size = 0;
note_start = 0;
note_end = 0;
segs = alloca(sizeof(segs[0]) * hdr->e_phnum);
stack_flags = RTLD_DEFAULT_STACK_PF_EXEC | PF_R | PF_W;
while (phdr < phlimit) {
switch (phdr->p_type) {
case PT_INTERP:
phinterp = phdr;
break;
case PT_LOAD:
segs[++nsegs] = phdr;
if ((segs[nsegs]->p_align & (PAGE_SIZE - 1)) != 0) {
_rtld_error("%s: PT_LOAD segment %d not page-aligned",
path, nsegs);
goto error;
}
break;
case PT_PHDR:
phdr_vaddr = phdr->p_vaddr;
phsize = phdr->p_memsz;
break;
case PT_DYNAMIC:
phdyn = phdr;
break;
case PT_TLS:
phtls = phdr;
break;
case PT_GNU_STACK:
stack_flags = phdr->p_flags;
break;
case PT_GNU_RELRO:
relro_page = phdr->p_vaddr;
relro_size = phdr->p_memsz;
break;
case PT_NOTE:
if (phdr->p_offset > PAGE_SIZE ||
phdr->p_offset + phdr->p_filesz > PAGE_SIZE)
break;
note_start = (Elf_Addr)(char *)hdr + phdr->p_offset;
note_end = note_start + phdr->p_filesz;
break;
}
++phdr;
}
if (phdyn == NULL) {
_rtld_error("%s: object is not dynamically-linked", path);
goto error;
}
if (nsegs < 0) {
_rtld_error("%s: too few PT_LOAD segments", path);
goto error;
}
/*
* Map the entire address space of the object, to stake out our
* contiguous region, and to establish the base address for relocation.
*/
base_vaddr = trunc_page(segs[0]->p_vaddr);
base_vlimit = round_page(segs[nsegs]->p_vaddr + segs[nsegs]->p_memsz);
mapsize = base_vlimit - base_vaddr;
base_addr = hdr->e_type == ET_EXEC ? (caddr_t) base_vaddr : NULL;
mapbase = mmap(base_addr, mapsize, PROT_NONE, MAP_ANON | MAP_PRIVATE |
MAP_NOCORE, -1, 0);
if (mapbase == (caddr_t) -1) {
_rtld_error("%s: mmap of entire address space failed: %s",
path, rtld_strerror(errno));
goto error;
}
if (base_addr != NULL && mapbase != base_addr) {
_rtld_error("%s: mmap returned wrong address: wanted %p, got %p",
path, base_addr, mapbase);
goto error1;
}
for (i = 0; i <= nsegs; i++) {
/* Overlay the segment onto the proper region. */
data_offset = trunc_page(segs[i]->p_offset);
data_vaddr = trunc_page(segs[i]->p_vaddr);
data_vlimit = round_page(segs[i]->p_vaddr + segs[i]->p_filesz);
data_addr = mapbase + (data_vaddr - base_vaddr);
data_prot = convert_prot(segs[i]->p_flags);
data_flags = convert_flags(segs[i]->p_flags) | MAP_FIXED;
if (mmap(data_addr, data_vlimit - data_vaddr, data_prot,
data_flags | MAP_PREFAULT_READ, fd, data_offset) == (caddr_t) -1) {
_rtld_error("%s: mmap of data failed: %s", path,
rtld_strerror(errno));
goto error1;
}
/* Do BSS setup */
if (segs[i]->p_filesz != segs[i]->p_memsz) {
/* Clear any BSS in the last page of the segment. */
clear_vaddr = segs[i]->p_vaddr + segs[i]->p_filesz;
clear_addr = mapbase + (clear_vaddr - base_vaddr);
clear_page = mapbase + (trunc_page(clear_vaddr) - base_vaddr);
if ((nclear = data_vlimit - clear_vaddr) > 0) {
/* Make sure the end of the segment is writable */
if ((data_prot & PROT_WRITE) == 0 && -1 ==
mprotect(clear_page, PAGE_SIZE, data_prot|PROT_WRITE)) {
_rtld_error("%s: mprotect failed: %s", path,
rtld_strerror(errno));
goto error1;
}
memset(clear_addr, 0, nclear);
/* Reset the data protection back */
if ((data_prot & PROT_WRITE) == 0)
mprotect(clear_page, PAGE_SIZE, data_prot);
}
/* Overlay the BSS segment onto the proper region. */
bss_vaddr = data_vlimit;
bss_vlimit = round_page(segs[i]->p_vaddr + segs[i]->p_memsz);
bss_addr = mapbase + (bss_vaddr - base_vaddr);
if (bss_vlimit > bss_vaddr) { /* There is something to do */
if (mmap(bss_addr, bss_vlimit - bss_vaddr, data_prot,
data_flags | MAP_ANON, -1, 0) == (caddr_t)-1) {
_rtld_error("%s: mmap of bss failed: %s", path,
rtld_strerror(errno));
goto error1;
}
}
}
if (phdr_vaddr == 0 && data_offset <= hdr->e_phoff &&
(data_vlimit - data_vaddr + data_offset) >=
(hdr->e_phoff + hdr->e_phnum * sizeof (Elf_Phdr))) {
phdr_vaddr = data_vaddr + hdr->e_phoff - data_offset;
}
}
obj = obj_new();
if (sb != NULL) {
obj->dev = sb->st_dev;
obj->ino = sb->st_ino;
}
obj->mapbase = mapbase;
obj->mapsize = mapsize;
obj->textsize = round_page(segs[0]->p_vaddr + segs[0]->p_memsz) -
base_vaddr;
obj->vaddrbase = base_vaddr;
obj->relocbase = mapbase - base_vaddr;
obj->dynamic = (const Elf_Dyn *) (obj->relocbase + phdyn->p_vaddr);
if (hdr->e_entry != 0)
obj->entry = (caddr_t) (obj->relocbase + hdr->e_entry);
if (phdr_vaddr != 0) {
obj->phdr = (const Elf_Phdr *) (obj->relocbase + phdr_vaddr);
} else {
obj->phdr = malloc(phsize);
if (obj->phdr == NULL) {
obj_free(obj);
_rtld_error("%s: cannot allocate program header", path);
goto error1;
}
memcpy((char *)obj->phdr, (char *)hdr + hdr->e_phoff, phsize);
obj->phdr_alloc = true;
}
obj->phsize = phsize;
if (phinterp != NULL)
obj->interp = (const char *) (obj->relocbase + phinterp->p_vaddr);
if (phtls != NULL) {
tls_dtv_generation++;
obj->tlsindex = ++tls_max_index;
obj->tlssize = phtls->p_memsz;
obj->tlsalign = phtls->p_align;
obj->tlsinitsize = phtls->p_filesz;
obj->tlsinit = mapbase + phtls->p_vaddr;
}
obj->stack_flags = stack_flags;
obj->relro_page = obj->relocbase + trunc_page(relro_page);
obj->relro_size = round_page(relro_size);
if (note_start < note_end)
digest_notes(obj, note_start, note_end);
munmap(hdr, PAGE_SIZE);
return (obj);
error1:
munmap(mapbase, mapsize);
error:
munmap(hdr, PAGE_SIZE);
return (NULL);
}
static Elf_Ehdr *
get_elf_header(int fd, const char *path)
{
Elf_Ehdr *hdr;
hdr = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_PRIVATE | MAP_PREFAULT_READ,
fd, 0);
if (hdr == (Elf_Ehdr *)MAP_FAILED) {
_rtld_error("%s: read error: %s", path, rtld_strerror(errno));
return (NULL);
}
/* Make sure the file is valid */
if (!IS_ELF(*hdr)) {
_rtld_error("%s: invalid file format", path);
goto error;
}
if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
_rtld_error("%s: unsupported file layout", path);
goto error;
}
if (hdr->e_ident[EI_VERSION] != EV_CURRENT ||
hdr->e_version != EV_CURRENT) {
_rtld_error("%s: unsupported file version", path);
goto error;
}
if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
_rtld_error("%s: unsupported file type", path);
goto error;
}
if (hdr->e_machine != ELF_TARG_MACH) {
_rtld_error("%s: unsupported machine", path);
goto error;
}
/*
* We rely on the program header being in the first page. This is
* not strictly required by the ABI specification, but it seems to
* always true in practice. And, it simplifies things considerably.
*/
if (hdr->e_phentsize != sizeof(Elf_Phdr)) {
_rtld_error(
"%s: invalid shared object: e_phentsize != sizeof(Elf_Phdr)", path);
goto error;
}
if (hdr->e_phoff + hdr->e_phnum * sizeof(Elf_Phdr) >
(size_t)PAGE_SIZE) {
_rtld_error("%s: program header too large", path);
goto error;
}
return (hdr);
error:
munmap(hdr, PAGE_SIZE);
return (NULL);
}
void
obj_free(Obj_Entry *obj)
{
Objlist_Entry *elm;
if (obj->tls_done)
free_tls_offset(obj);
while (obj->needed != NULL) {
Needed_Entry *needed = obj->needed;
obj->needed = needed->next;
free(needed);
}
while (!STAILQ_EMPTY(&obj->names)) {
Name_Entry *entry = STAILQ_FIRST(&obj->names);
STAILQ_REMOVE_HEAD(&obj->names, link);
free(entry);
}
while (!STAILQ_EMPTY(&obj->dldags)) {
elm = STAILQ_FIRST(&obj->dldags);
STAILQ_REMOVE_HEAD(&obj->dldags, link);
free(elm);
}
while (!STAILQ_EMPTY(&obj->dagmembers)) {
elm = STAILQ_FIRST(&obj->dagmembers);
STAILQ_REMOVE_HEAD(&obj->dagmembers, link);
free(elm);
}
if (obj->vertab)
free(obj->vertab);
if (obj->origin_path)
free(obj->origin_path);
if (obj->z_origin)
free(obj->rpath);
if (obj->priv)
free(obj->priv);
if (obj->path)
free(obj->path);
if (obj->phdr_alloc)
free((void *)obj->phdr);
free(obj);
}
Obj_Entry *
obj_new(void)
{
Obj_Entry *obj;
obj = CNEW(Obj_Entry);
STAILQ_INIT(&obj->dldags);
STAILQ_INIT(&obj->dagmembers);
STAILQ_INIT(&obj->names);
return obj;
}
/*
* Given a set of ELF protection flags, return the corresponding protection
* flags for MMAP.
*/
static int
convert_prot(int elfflags)
{
int prot = 0;
if (elfflags & PF_R)
prot |= PROT_READ;
if (elfflags & PF_W)
prot |= PROT_WRITE;
if (elfflags & PF_X)
prot |= PROT_EXEC;
return prot;
}
static int
convert_flags(int elfflags)
{
int flags = MAP_PRIVATE; /* All mappings are private */
/*
* Readonly mappings are marked "MAP_NOCORE", because they can be
* reconstructed by a debugger.
*/
if (!(elfflags & PF_W))
flags |= MAP_NOCORE;
return flags;
}