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