Permalink
Cannot retrieve contributors at this time
Name already in use
A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?
glibc/elf/check-textrel.c
Go to fileThis commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
191 lines (157 sloc)
4.76 KB
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
/* Check for text relocations in DSOs. | |
Copyright (C) 2002, 2003, 2006 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
Contribute by Ulrich Drepper <drepper@redhat.com>. 2002. | |
The GNU C Library is free software; you can redistribute it and/or | |
modify it under the terms of the GNU Lesser General Public | |
License as published by the Free Software Foundation; either | |
version 2.1 of the License, or (at your option) any later version. | |
The GNU C Library is distributed in the hope that it will be useful, | |
but WITHOUT ANY WARRANTY; without even the implied warranty of | |
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
Lesser General Public License for more details. | |
You should have received a copy of the GNU Lesser General Public | |
License along with the GNU C Library; if not, write to the Free | |
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
02111-1307 USA. */ | |
#include <byteswap.h> | |
#include <elf.h> | |
#include <endian.h> | |
#include <fcntl.h> | |
#include <stdio.h> | |
#include <stdlib.h> | |
#include <string.h> | |
#include <unistd.h> | |
#ifdef BITS | |
# define AB(name) _AB (name, BITS) | |
# define _AB(name, bits) __AB (name, bits) | |
# define __AB(name, bits) name##bits | |
# define E(name) _E (name, BITS) | |
# define _E(name, bits) __E (name, bits) | |
# define __E(name, bits) Elf##bits##_##name | |
# define SWAP(val) \ | |
({ __typeof (val) __res; \ | |
if (((ehdr.e_ident[EI_DATA] == ELFDATA2MSB \ | |
&& BYTE_ORDER == LITTLE_ENDIAN) \ | |
|| (ehdr.e_ident[EI_DATA] == ELFDATA2LSB \ | |
&& BYTE_ORDER == BIG_ENDIAN)) \ | |
&& sizeof (val) != 1) \ | |
{ \ | |
if (sizeof (val) == 2) \ | |
__res = bswap_16 (val); \ | |
else if (sizeof (val) == 4) \ | |
__res = bswap_32 (val); \ | |
else \ | |
__res = bswap_64 (val); \ | |
} \ | |
else \ | |
__res = (val); \ | |
__res; }) | |
static int | |
AB(handle_file) (const char *fname, int fd) | |
{ | |
E(Ehdr) ehdr; | |
if (pread (fd, &ehdr, sizeof (ehdr), 0) != sizeof (ehdr)) | |
{ | |
read_error: | |
printf ("%s: read error: %m\n", fname); | |
return 1; | |
} | |
const size_t phnum = SWAP (ehdr.e_phnum); | |
const size_t phentsize = SWAP (ehdr.e_phentsize); | |
/* Read the program header. */ | |
E(Phdr) *phdr = alloca (phentsize * phnum); | |
if (pread (fd, phdr, phentsize * phnum, SWAP (ehdr.e_phoff)) | |
!= phentsize * phnum) | |
goto read_error; | |
/* Search for the PT_DYNAMIC entry. */ | |
size_t cnt; | |
E(Phdr) *dynphdr = NULL; | |
for (cnt = 0; cnt < phnum; ++cnt) | |
if (SWAP (phdr[cnt].p_type) == PT_DYNAMIC) | |
dynphdr = &phdr[cnt]; | |
else if (SWAP (phdr[cnt].p_type) == PT_LOAD | |
&& (SWAP (phdr[cnt].p_flags) & (PF_X | PF_W)) == (PF_X | PF_W)) | |
{ | |
printf ("%s: segment %zu is executable and writable\n", | |
fname, cnt); | |
return 1; | |
} | |
if (dynphdr == NULL) | |
{ | |
printf ("%s: no DYNAMIC segment found\n", fname); | |
return 1; | |
} | |
/* Read the dynamic segment. */ | |
size_t pmemsz = SWAP(dynphdr->p_memsz); | |
E(Dyn) *dyn = alloca (pmemsz); | |
if (pread (fd, dyn, pmemsz, SWAP(dynphdr->p_offset)) != pmemsz) | |
goto read_error; | |
/* Search for an DT_TEXTREL entry of DT_FLAGS with the DF_TEXTREL | |
bit set. */ | |
for (cnt = 0; (cnt + 1) * sizeof (E(Dyn)) - 1 < pmemsz; ++cnt) | |
{ | |
unsigned int tag = SWAP (dyn[cnt].d_tag); | |
if (tag == DT_NULL) | |
/* We reached the end. */ | |
break; | |
if (tag == DT_TEXTREL | |
|| (tag == DT_FLAGS | |
&& (SWAP (dyn[cnt].d_un.d_val) & DF_TEXTREL) != 0)) | |
{ | |
/* Urgh! The DSO has text relocations. */ | |
printf ("%s: text relocations used\n", fname); | |
return 1; | |
} | |
} | |
printf ("%s: OK\n", fname); | |
return 0; | |
} | |
# undef BITS | |
#else | |
# define BITS 32 | |
# include "check-textrel.c" | |
# define BITS 64 | |
# include "check-textrel.c" | |
static int | |
handle_file (const char *fname) | |
{ | |
int fd = open (fname, O_RDONLY); | |
if (fd == -1) | |
{ | |
printf ("cannot open %s: %m\n", fname); | |
return 1; | |
} | |
/* Read was is supposed to be the ELF header. Read the initial | |
bytes to determine whether this is a 32 or 64 bit file. */ | |
char ident[EI_NIDENT]; | |
if (read (fd, ident, EI_NIDENT) != EI_NIDENT) | |
{ | |
printf ("%s: read error: %m\n", fname); | |
close (fd); | |
return 1; | |
} | |
if (memcmp (&ident[EI_MAG0], ELFMAG, SELFMAG) != 0) | |
{ | |
printf ("%s: not an ELF file\n", fname); | |
close (fd); | |
return 1; | |
} | |
int result; | |
if (ident[EI_CLASS] == ELFCLASS64) | |
result = handle_file64 (fname, fd); | |
else | |
result = handle_file32 (fname, fd); | |
close (fd); | |
return result; | |
} | |
int | |
main (int argc, char *argv[]) | |
{ | |
int cnt; | |
int result = 0; | |
for (cnt = 1; cnt < argc; ++cnt) | |
result |= handle_file (argv[cnt]); | |
return result; | |
} | |
#endif |