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glibc/elf/check-localplt.c
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/* Show local PLT use in DSOs. | |
Copyright (C) 2006 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
Contribute by Ulrich Drepper <drepper@redhat.com>. 2006. | |
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 <stdint.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 EE(name) _EE (name, BITS) | |
# define _EE(name, bits) __EE (name, bits) | |
# define __EE(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]; | |
break; | |
} | |
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 (pread64 (fd, dyn, pmemsz, SWAP(dynphdr->p_offset)) != pmemsz) | |
goto read_error; | |
/* Search for an DT_PLTREL, DT_JMPREL, DT_PLTRELSZ, DT_STRTAB, | |
DT_STRSZ, and DT_SYMTAB entries. */ | |
size_t pltrel_idx = SIZE_MAX; | |
size_t jmprel_idx = SIZE_MAX; | |
size_t pltrelsz_idx = SIZE_MAX; | |
size_t strtab_idx = SIZE_MAX; | |
size_t strsz_idx = SIZE_MAX; | |
size_t symtab_idx = SIZE_MAX; | |
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_PLTREL) | |
pltrel_idx = cnt; | |
else if (tag == DT_JMPREL) | |
jmprel_idx = cnt; | |
else if (tag == DT_PLTRELSZ) | |
pltrelsz_idx = cnt; | |
else if (tag == DT_STRTAB) | |
strtab_idx = cnt; | |
else if (tag == DT_STRSZ) | |
strsz_idx = cnt; | |
else if (tag == DT_SYMTAB) | |
symtab_idx = cnt; | |
} | |
if (pltrel_idx == SIZE_MAX || jmprel_idx == SIZE_MAX | |
|| pltrelsz_idx == SIZE_MAX || strtab_idx == SIZE_MAX | |
|| strsz_idx == SIZE_MAX || symtab_idx == SIZE_MAX) | |
{ | |
puts ("not all PLT information found"); | |
return 1; | |
} | |
E(Xword) relsz = SWAP (dyn[pltrelsz_idx].d_un.d_val); | |
void *relmem = NULL; | |
char *strtab = NULL; | |
E(Xword) symtab_offset = 0; | |
/* Find the offset of DT_JMPREL and load the data. */ | |
for (cnt = 0; cnt < phnum; ++cnt) | |
if (SWAP (phdr[cnt].p_type) == PT_LOAD) | |
{ | |
E(Addr) vaddr = SWAP (phdr[cnt].p_vaddr); | |
E(Xword) memsz = SWAP (phdr[cnt].p_memsz); | |
if (vaddr <= SWAP (dyn[jmprel_idx].d_un.d_val) | |
&& vaddr + memsz >= SWAP (dyn[jmprel_idx].d_un.d_val) + relsz) | |
{ | |
relmem = alloca (SWAP (dyn[pltrelsz_idx].d_un.d_val)); | |
if (pread64 (fd, relmem, relsz, | |
SWAP (phdr[cnt].p_offset) | |
+ SWAP (dyn[jmprel_idx].d_un.d_val) - vaddr) | |
!= relsz) | |
{ | |
puts ("cannot read JMPREL"); | |
return 1; | |
} | |
} | |
if (vaddr <= SWAP (dyn[symtab_idx].d_un.d_val) | |
&& vaddr + memsz > SWAP (dyn[symtab_idx].d_un.d_val)) | |
symtab_offset = (SWAP (phdr[cnt].p_offset) | |
+ SWAP (dyn[symtab_idx].d_un.d_val) - vaddr); | |
if (vaddr <= SWAP (dyn[strtab_idx].d_un.d_val) | |
&& vaddr + memsz >= (SWAP (dyn[strtab_idx].d_un.d_val) | |
+ SWAP(dyn[strsz_idx].d_un.d_val))) | |
{ | |
strtab = alloca (SWAP(dyn[strsz_idx].d_un.d_val)); | |
if (pread64 (fd, strtab, SWAP(dyn[strsz_idx].d_un.d_val), | |
SWAP (phdr[cnt].p_offset) | |
+ SWAP (dyn[strtab_idx].d_un.d_val) - vaddr) | |
!= SWAP(dyn[strsz_idx].d_un.d_val)) | |
{ | |
puts ("cannot read STRTAB"); | |
return 1; | |
} | |
} | |
} | |
if (relmem == NULL || strtab == NULL || symtab_offset == 0) | |
{ | |
puts ("couldn't load PLT data"); | |
return 1; | |
} | |
if (SWAP (dyn[pltrel_idx].d_un.d_val) == DT_RELA) | |
for (E(Rela) *rela = relmem; (char *) rela - (char *) relmem < relsz; | |
++rela) | |
{ | |
E(Sym) sym; | |
if (pread64 (fd, &sym, sizeof (sym), | |
symtab_offset | |
+ EE(R_SYM) (SWAP (rela->r_info)) * sizeof (sym)) | |
!= sizeof (sym)) | |
{ | |
puts ("cannot read symbol"); | |
return 1; | |
} | |
if (sym.st_value != 0) | |
/* This symbol is locally defined. */ | |
printf ("%s: %s\n", basename (fname), strtab + SWAP (sym.st_name)); | |
} | |
else | |
for (E(Rel) *rel = relmem; (char *) rel - (char *) relmem < relsz; ++rel) | |
{ | |
E(Sym) sym; | |
if (pread64 (fd, &sym, sizeof (sym), | |
symtab_offset | |
+ EE(R_SYM) (SWAP (rel->r_info)) * sizeof (sym)) | |
!= sizeof (sym)) | |
{ | |
puts ("cannot read symbol"); | |
return 1; | |
} | |
if (sym.st_value != 0) | |
/* This symbol is locally defined. */ | |
printf ("%s: %s\n", basename (fname), strtab + SWAP (sym.st_name)); | |
} | |
return 0; | |
} | |
# undef BITS | |
#else | |
# define BITS 32 | |
# include "check-localplt.c" | |
# define BITS 64 | |
# include "check-localplt.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 |