Reviewed by: emaste Discussed with: jrtc27 Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D32960
514 lines
14 KiB
C
514 lines
14 KiB
C
/*-
|
|
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
|
|
*
|
|
* 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.
|
|
*
|
|
* $FreeBSD$
|
|
*/
|
|
|
|
#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 *, const struct stat *,
|
|
Elf_Phdr **phdr);
|
|
static int convert_flags(int); /* Elf flags -> mmap flags */
|
|
|
|
int __getosreldate(void);
|
|
|
|
static bool
|
|
phdr_in_zero_page(const Elf_Ehdr *hdr)
|
|
{
|
|
return (hdr->e_phoff + hdr->e_phnum * sizeof(Elf_Phdr) <=
|
|
(size_t)PAGE_SIZE);
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
int base_flags;
|
|
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;
|
|
char *note_map;
|
|
size_t note_map_len;
|
|
Elf_Addr text_end;
|
|
|
|
hdr = get_elf_header(fd, path, sb, &phdr);
|
|
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.
|
|
*/
|
|
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;
|
|
note_map = NULL;
|
|
note_map_len = 0;
|
|
segs = alloca(sizeof(segs[0]) * hdr->e_phnum);
|
|
stack_flags = RTLD_DEFAULT_STACK_PF_EXEC | PF_R | PF_W;
|
|
text_end = 0;
|
|
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;
|
|
}
|
|
if ((segs[nsegs]->p_flags & PF_X) == PF_X) {
|
|
text_end = MAX(text_end,
|
|
round_page(segs[nsegs]->p_vaddr + segs[nsegs]->p_memsz));
|
|
}
|
|
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) {
|
|
note_map_len = round_page(phdr->p_offset +
|
|
phdr->p_filesz) - trunc_page(phdr->p_offset);
|
|
note_map = mmap(NULL, note_map_len, PROT_READ,
|
|
MAP_PRIVATE, fd, trunc_page(phdr->p_offset));
|
|
if (note_map == MAP_FAILED) {
|
|
_rtld_error("%s: error mapping PT_NOTE (%d)", path, errno);
|
|
goto error;
|
|
}
|
|
note_start = (Elf_Addr)(note_map + phdr->p_offset -
|
|
trunc_page(phdr->p_offset));
|
|
} else {
|
|
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 = (caddr_t) base_vaddr;
|
|
base_flags = __getosreldate() >= P_OSREL_MAP_GUARD ? MAP_GUARD :
|
|
MAP_PRIVATE | MAP_ANON | MAP_NOCORE;
|
|
if (npagesizes > 1 && round_page(segs[0]->p_filesz) >= pagesizes[1])
|
|
base_flags |= MAP_ALIGNED_SUPER;
|
|
if (base_vaddr != 0)
|
|
base_flags |= MAP_FIXED | MAP_EXCL;
|
|
|
|
mapbase = mmap(base_addr, mapsize, PROT_NONE, base_flags, -1, 0);
|
|
if (mapbase == MAP_FAILED) {
|
|
_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 (data_vlimit != data_vaddr &&
|
|
mmap(data_addr, data_vlimit - data_vaddr, data_prot,
|
|
data_flags | MAP_PREFAULT_READ, fd, data_offset) == MAP_FAILED) {
|
|
_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) == MAP_FAILED) {
|
|
_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->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(__DECONST(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->tlspoffset = phtls->p_offset;
|
|
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 = trunc_page(relro_page + relro_size) -
|
|
trunc_page(relro_page);
|
|
if (note_start < note_end)
|
|
digest_notes(obj, note_start, note_end);
|
|
if (note_map != NULL)
|
|
munmap(note_map, note_map_len);
|
|
munmap(hdr, PAGE_SIZE);
|
|
return (obj);
|
|
|
|
error1:
|
|
munmap(mapbase, mapsize);
|
|
error:
|
|
if (note_map != NULL && note_map != MAP_FAILED)
|
|
munmap(note_map, note_map_len);
|
|
if (!phdr_in_zero_page(hdr))
|
|
munmap(phdr, hdr->e_phnum * sizeof(phdr[0]));
|
|
munmap(hdr, PAGE_SIZE);
|
|
return (NULL);
|
|
}
|
|
|
|
bool
|
|
check_elf_headers(const Elf_Ehdr *hdr, const char *path)
|
|
{
|
|
if (!IS_ELF(*hdr)) {
|
|
_rtld_error("%s: invalid file format", path);
|
|
return (false);
|
|
}
|
|
if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
|
|
hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
|
|
_rtld_error("%s: unsupported file layout", path);
|
|
return (false);
|
|
}
|
|
if (hdr->e_ident[EI_VERSION] != EV_CURRENT ||
|
|
hdr->e_version != EV_CURRENT) {
|
|
_rtld_error("%s: unsupported file version", path);
|
|
return (false);
|
|
}
|
|
if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
|
|
_rtld_error("%s: unsupported file type", path);
|
|
return (false);
|
|
}
|
|
if (hdr->e_machine != ELF_TARG_MACH) {
|
|
_rtld_error("%s: unsupported machine", path);
|
|
return (false);
|
|
}
|
|
if (hdr->e_phentsize != sizeof(Elf_Phdr)) {
|
|
_rtld_error(
|
|
"%s: invalid shared object: e_phentsize != sizeof(Elf_Phdr)", path);
|
|
return (false);
|
|
}
|
|
return (true);
|
|
}
|
|
|
|
static Elf_Ehdr *
|
|
get_elf_header(int fd, const char *path, const struct stat *sbp,
|
|
Elf_Phdr **phdr_p)
|
|
{
|
|
Elf_Ehdr *hdr;
|
|
Elf_Phdr *phdr;
|
|
|
|
/* Make sure file has enough data for the ELF header */
|
|
if (sbp != NULL && sbp->st_size < (off_t)sizeof(Elf_Ehdr)) {
|
|
_rtld_error("%s: invalid file format", path);
|
|
return (NULL);
|
|
}
|
|
|
|
hdr = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_PRIVATE | MAP_PREFAULT_READ,
|
|
fd, 0);
|
|
if (hdr == MAP_FAILED) {
|
|
_rtld_error("%s: read error: %s", path, rtld_strerror(errno));
|
|
return (NULL);
|
|
}
|
|
|
|
/* Make sure the file is valid */
|
|
if (!check_elf_headers(hdr, 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 (phdr_in_zero_page(hdr)) {
|
|
phdr = (Elf_Phdr *)((char *)hdr + hdr->e_phoff);
|
|
} else {
|
|
phdr = mmap(NULL, hdr->e_phnum * sizeof(phdr[0]),
|
|
PROT_READ, MAP_PRIVATE | MAP_PREFAULT_READ, fd,
|
|
hdr->e_phoff);
|
|
if (phdr == MAP_FAILED) {
|
|
_rtld_error("%s: error mapping phdr: %s", path,
|
|
rtld_strerror(errno));
|
|
goto error;
|
|
}
|
|
}
|
|
*phdr_p = phdr;
|
|
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(__DECONST(void*, obj->rpath));
|
|
if (obj->priv)
|
|
free(obj->priv);
|
|
if (obj->path)
|
|
free(obj->path);
|
|
if (obj->phdr_alloc)
|
|
free(__DECONST(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.
|
|
*/
|
|
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;
|
|
}
|