/*-
* SPDX-License-Identifier: BSD-4-Clause
*
* Copyright (c) 1997 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 by Christopher G. Demetriou
* for the NetBSD Project.
* 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.
*/
#include <sys/cdefs.h>
#ifndef lint
#if 0
__RCSID("$NetBSD: exec_elf32.c,v 1.6 1999/09/20 04:12:16 christos Exp $");
#endif
#endif
#ifndef ELFSIZE
#define ELFSIZE 32
#endif
#include <sys/types.h>
#include <sys/endian.h>
#include <sys/stat.h>
#include <errno.h>
#include <limits.h>
#include <stddef.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))
#define __ELF_WORD_SIZE ELFSIZE
#if (ELFSIZE == 32)
#include <sys/elf32.h>
#define xewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x))
#define htoxew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x))
#define wewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x))
#define htowew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x))
#elif (ELFSIZE == 64)
#include <sys/elf64.h>
#define xewtoh(x) ((data == ELFDATA2MSB) ? be64toh(x) : le64toh(x))
#define htoxew(x) ((data == ELFDATA2MSB) ? htobe64(x) : htole64(x))
/* elf64 Elf64_Word are 32 bits */
#define wewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x))
#define htowew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x))
#endif
#include <sys/elf_generic.h>
#define CONCAT(x,y) __CONCAT(x,y)
#define ELFNAME(x) CONCAT(elf,CONCAT(ELFSIZE,CONCAT(_,x)))
#define ELFNAME2(x,y) CONCAT(x,CONCAT(_elf,CONCAT(ELFSIZE,CONCAT(_,y))))
#define ELFNAMEEND(x) CONCAT(x,CONCAT(_elf,ELFSIZE))
#define ELFDEFNNAME(x) CONCAT(ELF,CONCAT(ELFSIZE,CONCAT(_,x)))
#ifndef ELFCLASS
#define ELFCLASS CONCAT(ELFCLASS,ELFSIZE)
#endif
#define xe16toh(x) ((data == ELFDATA2MSB) ? be16toh(x) : le16toh(x))
#define xe32toh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x))
#define htoxe32(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x))
struct shlayout {
Elf_Shdr *shdr;
void *bufp;
};
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 ((size_t)(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 ((size_t)(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 __unused)
{
Elf_Ehdr eh;
struct stat sb;
unsigned char data;
/*
* Check the header to make sure it's an ELF file (of the
* appropriate size).
*/
if (fstat(fd, &sb) == -1)
return 0;
if (sb.st_size < (off_t)(sizeof eh))
return 0;
if (read(fd, &eh, sizeof eh) != sizeof eh)
return 0;
if (IS_ELF(eh) == 0 || eh.e_ident[EI_CLASS] != ELFCLASS)
return 0;
data = eh.e_ident[EI_DATA];
switch (xe16toh(eh.e_machine)) {
case EM_386: break;
case EM_ALPHA: break;
#ifndef EM_AARCH64
#define EM_AARCH64 183
#endif
case EM_AARCH64: break;
case EM_ARM: break;
case EM_MIPS: break;
case /* EM_MIPS_RS3_LE */ EM_MIPS_RS4_BE: break;
case EM_PPC: break;
case EM_PPC64: break;
#ifndef EM_RISCV
#define EM_RISCV 243
#endif
case EM_RISCV: break;
case EM_S390: break;
case EM_SPARCV9: break;
case EM_X86_64: break;
/* 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;
struct shlayout *layoutp = NULL;
Elf_Shdr *shdrp = NULL, *symtabshdr, *strtabshdr, *shstrtabshdr;
Elf_Shdr shdrshdr;
Elf_Sym *symtabp = NULL;
char *shstrtabp = NULL, *strtabp = NULL;
Elf_Size nsyms, ewi;
Elf_Off off;
ssize_t shdrsize;
int rv, i, weird, l, m, r, strtabidx;
size_t nstrtab_size, nstrtab_nextoff, fn_size, size;
char *nstrtabp = NULL;
unsigned char data;
const char *weirdreason = NULL;
void *buf;
Elf_Half shnum;
rv = 0;
if (xreadatoff(fd, &ehdr, 0, sizeof ehdr, fn) != sizeof ehdr)
goto bad;
data = ehdr.e_ident[EI_DATA];
shnum = xe16toh(ehdr.e_shnum);
shdrsize = shnum * xe16toh(ehdr.e_shentsize);
if ((shdrp = xmalloc(shdrsize, fn, "section header table")) == NULL)
goto bad;
if (xreadatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) !=
shdrsize)
goto bad;
symtabshdr = strtabshdr = shstrtabshdr = NULL;
weird = 0;
for (i = 0; i < shnum; i++) {
switch (xe32toh(shdrp[i].sh_type)) {
case SHT_SYMTAB:
if (symtabshdr != NULL) {
weird = 1;
weirdreason = "multiple symbol tables";
}
symtabshdr = &shdrp[i];
strtabshdr = &shdrp[xe32toh(shdrp[i].sh_link)];
break;
case SHT_STRTAB:
if (i == xe16toh(ehdr.e_shstrndx))
shstrtabshdr = &shdrp[i];
break;
}
}
if (symtabshdr == NULL)
goto out;
if (strtabshdr == NULL) {
weird = 1;
weirdreason = "string table does not exist";
}
if (shstrtabshdr == NULL) {
weird = 1;
weirdreason = "section header string table does not exist";
}
if (strtabshdr == shstrtabshdr) {
weird = 1;
weirdreason = "combined strtab and shstrtab not supported";
}
if (weirdreason == NULL)
weirdreason = "unsupported";
if (weird) {
fprintf(stderr, "%s: weird executable (%s)\n", fn, weirdreason);
goto bad;
}
/*
* sort section layout table by offset
*/
layoutp = xmalloc((shnum + 1) * sizeof(struct shlayout),
fn, "layout table");
if (layoutp == NULL)
goto bad;
/* add a pseudo entry to represent the section header table */
shdrshdr.sh_offset = ehdr.e_shoff;
shdrshdr.sh_size = htoxew(shdrsize);
shdrshdr.sh_addralign = htoxew(ELFSIZE / 8);
layoutp[shnum].shdr = &shdrshdr;
/* insert and sort normal section headers */
for (i = shnum; i-- != 0;) {
l = i + 1;
r = shnum;
while (l <= r) {
m = ( l + r) / 2;
if (xewtoh(shdrp[i].sh_offset) >
xewtoh(layoutp[m].shdr->sh_offset))
l = m + 1;
else
r = m - 1;
}
if (r != i) {
memmove(&layoutp[i], &layoutp[i + 1],
sizeof(struct shlayout) * (r - i));
}
layoutp[r].shdr = &shdrp[i];
layoutp[r].bufp = NULL;
}
++shnum;
/*
* load up everything we need
*/
/* load section string table for debug use */
if ((size = xewtoh(shstrtabshdr->sh_size)) == 0)
goto bad;
if ((shstrtabp = xmalloc(size, fn, "section string table")) == NULL)
goto bad;
if ((size_t)xreadatoff(fd, shstrtabp, xewtoh(shstrtabshdr->sh_offset),
size, fn) != size)
goto bad;
if (shstrtabp[size - 1] != '\0')
goto bad;
/* we need symtab, strtab, and everything behind strtab */
strtabidx = INT_MAX;
for (i = 0; i < shnum; i++) {
if (layoutp[i].shdr == &shdrshdr) {
/* not load section header again */
layoutp[i].bufp = shdrp;
continue;
}
if (layoutp[i].shdr == shstrtabshdr) {
/* not load section string table again */
layoutp[i].bufp = shstrtabp;
continue;
}
if (layoutp[i].shdr == strtabshdr)
strtabidx = i;
if (layoutp[i].shdr == symtabshdr || i >= strtabidx) {
off = xewtoh(layoutp[i].shdr->sh_offset);
if ((size = xewtoh(layoutp[i].shdr->sh_size)) == 0)
goto bad;
layoutp[i].bufp = xmalloc(size, fn,
shstrtabp + xewtoh(layoutp[i].shdr->sh_name));
if (layoutp[i].bufp == NULL)
goto bad;
if ((size_t)xreadatoff(fd, layoutp[i].bufp, off, size, fn) !=
size)
goto bad;
/* set symbol table and string table */
if (layoutp[i].shdr == symtabshdr) {
symtabp = layoutp[i].bufp;
} else if (layoutp[i].shdr == strtabshdr) {
strtabp = layoutp[i].bufp;
if (strtabp[size - 1] != '\0')
goto bad;
}
}
}
nstrtab_size = 256;
nstrtabp = xmalloc(nstrtab_size, fn, "new string table");
if (nstrtabp == NULL)
goto bad;
nstrtab_nextoff = 0;
fn_size = strlen(fn);
/* Prepare data structures for symbol movement. */
nsyms = xewtoh(symtabshdr->sh_size) / xewtoh(symtabshdr->sh_entsize);
/* move symbols, making them local */
for (ewi = 0; ewi < nsyms; ewi++) {
Elf_Sym *sp = &symtabp[ewi];
const char *symname = strtabp + xe32toh(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 = htowew(nstrtab_nextoff);
/* if it's a keeper or is undefined, don't rename it. */
if (in_keep_list(symname) ||
(xe16toh(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;
}
strtabshdr->sh_size = htoxew(nstrtab_nextoff);
/*
* update section header table in ascending order of offset
*/
for (i = strtabidx + 1; i < shnum; i++) {
Elf_Off soff, align;
soff = xewtoh(layoutp[i - 1].shdr->sh_offset) +
xewtoh(layoutp[i - 1].shdr->sh_size);
align = xewtoh(layoutp[i].shdr->sh_addralign);
soff = (soff + (align - 1)) & ~(align - 1);
layoutp[i].shdr->sh_offset = htoxew(soff);
}
/*
* write data to the file in descending order of offset
*/
for (i = shnum; i-- != 0;) {
if (layoutp[i].shdr == strtabshdr) {
/* new string table */
buf = nstrtabp;
} else
buf = layoutp[i].bufp;
if (layoutp[i].shdr == &shdrshdr ||
layoutp[i].shdr == symtabshdr || i >= strtabidx) {
if (buf == NULL)
goto bad;
/*
* update the offset of section header table in elf
* header if needed.
*/
if (layoutp[i].shdr == &shdrshdr &&
ehdr.e_shoff != shdrshdr.sh_offset) {
ehdr.e_shoff = shdrshdr.sh_offset;
off = offsetof(Elf_Ehdr, e_shoff);
size = sizeof(Elf_Off);
if ((size_t)xwriteatoff(fd, &ehdr.e_shoff, off, size,
fn) != size)
goto bad;
}
off = xewtoh(layoutp[i].shdr->sh_offset);
size = xewtoh(layoutp[i].shdr->sh_size);
if ((size_t)xwriteatoff(fd, buf, off, size, fn) != size)
goto bad;
}
}
out:
if (layoutp != NULL) {
for (i = 0; i < shnum; i++) {
if (layoutp[i].bufp != NULL)
free(layoutp[i].bufp);
}
free(layoutp);
}
free(nstrtabp);
return (rv);
bad:
rv = 1;
goto out;
}
#endif /* include this size of ELF */
plain