NetBSD/usr.bin/crunch/crunchide/exec_elf32.c

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/* $NetBSD: exec_elf32.c,v 1.12 2000/06/14 17:26:00 cgd Exp $ */
/*
* Copyright (c) 1997, 1998 Christopher G. Demetriou
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed for the
* NetBSD Project. See http://www.netbsd.org/ for
* information about NetBSD.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* 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.
*
* <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>>
*/
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: exec_elf32.c,v 1.12 2000/06/14 17:26:00 cgd Exp $");
#endif
#ifndef ELFSIZE
#define ELFSIZE 32
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "extern.h"
#if (defined(NLIST_ELF32) && (ELFSIZE == 32)) || \
(defined(NLIST_ELF64) && (ELFSIZE == 64))
#include <sys/exec_elf.h>
struct listelem {
struct listelem *next;
void *mem;
off_t file;
size_t size;
};
static ssize_t
xreadatoff(int fd, void *buf, off_t off, size_t size, const char *fn)
{
ssize_t rv;
if (lseek(fd, off, SEEK_SET) != off) {
perror(fn);
return -1;
}
if ((rv = read(fd, buf, size)) != size) {
fprintf(stderr, "%s: read error: %s\n", fn,
rv == -1 ? strerror(errno) : "short read");
return -1;
}
return size;
}
static ssize_t
xwriteatoff(int fd, void *buf, off_t off, size_t size, const char *fn)
{
ssize_t rv;
if (lseek(fd, off, SEEK_SET) != off) {
perror(fn);
return -1;
}
if ((rv = write(fd, buf, size)) != size) {
fprintf(stderr, "%s: write error: %s\n", fn,
rv == -1 ? strerror(errno) : "short write");
return -1;
}
return size;
}
static void *
xmalloc(size_t size, const char *fn, const char *use)
{
void *rv;
rv = malloc(size);
if (rv == NULL)
fprintf(stderr, "%s: out of memory (allocating for %s)\n",
fn, use);
return (rv);
}
static void *
xrealloc(void *ptr, size_t size, const char *fn, const char *use)
{
void *rv;
rv = realloc(ptr, size);
if (rv == NULL) {
free(ptr);
fprintf(stderr, "%s: out of memory (reallocating for %s)\n",
fn, use);
}
return (rv);
}
int
ELFNAMEEND(check)(int fd, const char *fn)
{
Elf_Ehdr eh;
struct stat sb;
/*
* Check the header to maek sure it's an ELF file (of the
* appropriate size).
*/
if (fstat(fd, &sb) == -1)
return 0;
if (sb.st_size < sizeof eh)
return 0;
if (read(fd, &eh, sizeof eh) != sizeof eh)
return 0;
if (memcmp(eh.e_ident, ELFMAG, SELFMAG) != 0 ||
eh.e_ident[EI_CLASS] != ELFCLASS)
return 0;
switch (eh.e_machine) {
ELFDEFNNAME(MACHDEP_ID_CASES)
default:
return 0;
}
return 1;
}
/*
* This function 'hides' (some of) ELF executable file's symbols.
* It hides them by renaming them to "_$$hide$$ <filename> <symbolname>".
* Symbols in the global keep list, or which are marked as being undefined,
* are left alone.
*
* An old version of this code shuffled various tables around, turning
* global symbols to be hidden into local symbols. That lost on the
* mips, because CALL16 relocs must reference global symbols, and, if
* those symbols were being hidden, they were no longer global.
*
* The new renaming behaviour doesn't take global symbols out of the
* namespace. However, it's ... unlikely that there will ever be
* any collisions in practice because of the new method.
*/
int
ELFNAMEEND(hide)(int fd, const char *fn)
{
Elf_Ehdr ehdr;
Elf_Shdr *shdrp = NULL;
int symtabsnum, strtabsnum;
Elf_Sym *symtabp = NULL;
char *strtabp = NULL, *nstrtabp = NULL;
Elf_Word nsyms;
Elf_Off stroff, maxoff;
const char *weirdreason;
ssize_t shdrsize;
size_t nstrtab_size, nstrtab_nextoff, fn_size;
int rv, i, weird;
rv = 0;
if (xreadatoff(fd, &ehdr, 0, sizeof ehdr, fn) != sizeof ehdr)
goto bad;
shdrsize = ehdr.e_shnum * ehdr.e_shentsize;
if ((shdrp = xmalloc(shdrsize, fn, "section header table")) == NULL)
goto bad;
if (xreadatoff(fd, shdrp, ehdr.e_shoff, shdrsize, fn) != shdrsize)
goto bad;
symtabsnum = strtabsnum = -1;
maxoff = stroff = 0;
weird = 0;
weirdreason = "???";
for (i = 0; i < ehdr.e_shnum; i++) {
if (shdrp[i].sh_offset > maxoff) {
maxoff = shdrp[i].sh_offset;
}
switch (shdrp[i].sh_type) {
case SHT_SYMTAB:
if (!weird && symtabsnum != -1) {
weird = 1;
weirdreason = "multiple symbol tables";
}
symtabsnum = i;
strtabsnum = shdrp[i].sh_link;
stroff = shdrp[strtabsnum].sh_offset;
if (!weird && strtabsnum != (ehdr.e_shnum - 1)) {
weird = 1;
weirdreason = "string table not last section";
}
break;
}
}
if (symtabsnum == -1)
goto out;
if (!weird && strtabsnum == -1) {
weird = 1;
weirdreason = "no string table found";
}
if (!weird && stroff != maxoff) {
weird = 1;
weirdreason = "string table section not last in file";
}
if (weird) {
fprintf(stderr, "%s: weird executable (%s); unsupported\n", fn,
weirdreason);
goto bad;
}
/*
* load up everything we need
*/
/* symbol table */
if ((symtabp = xmalloc(shdrp[symtabsnum].sh_size, fn, "symbol table"))
== NULL)
goto bad;
if (xreadatoff(fd, symtabp, shdrp[symtabsnum].sh_offset,
shdrp[symtabsnum].sh_size, fn) != shdrp[symtabsnum].sh_size)
goto bad;
/* string table */
if ((strtabp = xmalloc(shdrp[strtabsnum].sh_size, fn, "string table"))
== NULL)
goto bad;
if (xreadatoff(fd, strtabp, shdrp[strtabsnum].sh_offset,
shdrp[strtabsnum].sh_size, fn) != shdrp[strtabsnum].sh_size)
goto bad;
nsyms = shdrp[symtabsnum].sh_size / shdrp[symtabsnum].sh_entsize;
nstrtab_size = 256;
nstrtabp = xmalloc(nstrtab_size, fn, "new string table");
if (nstrtabp == NULL)
goto bad;
nstrtab_nextoff = 0;
fn_size = strlen(fn);
for (i = 0; i < nsyms; i++) {
Elf_Sym *sp = &symtabp[i];
const char *symname = strtabp + sp->st_name;
size_t newent_len;
/*
* make sure there's size for the next entry, even if it's
* as large as it can be.
*
* "_$$hide$$ <filename> <symname><NUL>" ->
* 9 + 3 + sizes of fn and sym name
*/
while ((nstrtab_size - nstrtab_nextoff) <
strlen(symname) + fn_size + 12) {
nstrtab_size *= 2;
nstrtabp = xrealloc(nstrtabp, nstrtab_size, fn,
"new string table");
if (nstrtabp == NULL)
goto bad;
}
sp->st_name = nstrtab_nextoff;
/* if it's a keeper or is undefined, don't rename it. */
if (in_keep_list(symname) ||
sp->st_shndx == SHN_UNDEF) {
newent_len = sprintf(nstrtabp + nstrtab_nextoff,
"%s", symname) + 1;
} else {
newent_len = sprintf(nstrtabp + nstrtab_nextoff,
"_$$hide$$ %s %s", fn, symname) + 1;
}
nstrtab_nextoff += newent_len;
}
shdrp[strtabsnum].sh_size = nstrtab_nextoff;
/*
* write new tables to the file
*/
if (xwriteatoff(fd, shdrp, ehdr.e_shoff, shdrsize, fn) != shdrsize)
goto bad;
if (xwriteatoff(fd, symtabp, shdrp[symtabsnum].sh_offset,
shdrp[symtabsnum].sh_size, fn) != shdrp[symtabsnum].sh_size)
goto bad;
if (xwriteatoff(fd, nstrtabp, shdrp[strtabsnum].sh_offset,
shdrp[strtabsnum].sh_size, fn) != shdrp[strtabsnum].sh_size)
goto bad;
out:
if (shdrp != NULL)
free(shdrp);
if (symtabp != NULL)
free(symtabp);
if (strtabp != NULL)
free(strtabp);
if (nstrtabp != NULL)
1999-09-20 08:12:16 +04:00
free(nstrtabp);
return (rv);
bad:
rv = 1;
goto out;
}
#endif /* include this size of ELF */