freebsd-dev/lib/libelf/libelf_phdr.c
Joseph Koshy f6c0f35e07 Keep shadow copies of the e_shnum', e_phnum' and `e_shstrndx'
members of the ELF Executable Header inside the library-private
`struct _Elf' descriptor and only update the underlying Elf{32,64}_Ehdr
structure on an elf_update(3) call.  These fields of the Ehdr
structure are technically `out of bounds' for an application program
per the ELF(3) API, but we've seen applications that initialize
a new Ehdr structure using memcpy(), messing up the library's
invariants. [1]

Implement elf_getphnum() and handle ELF objects with more than
64K program header table entries.

Reported by:	jb [1]
2006-12-25 02:22:22 +00:00

158 lines
4.0 KiB
C

/*-
* Copyright (c) 2006 Joseph Koshy
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
*
* $FreeBSD$
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <assert.h>
#include <gelf.h>
#include <libelf.h>
#include <stdlib.h>
#include "_libelf.h"
void *
_libelf_getphdr(Elf *e, int ec)
{
size_t phnum, phentsize;
size_t fsz, msz;
uint64_t phoff;
Elf32_Ehdr *eh32;
Elf64_Ehdr *eh64;
void *ehdr, *phdr;
void (*xlator)(char *_d, char *_s, size_t _c, int _swap);
assert(ec == ELFCLASS32 || ec == ELFCLASS64);
if (e == NULL) {
LIBELF_SET_ERROR(ARGUMENT, 0);
return (NULL);
}
if ((phdr = (ec == ELFCLASS32 ?
(void *) e->e_u.e_elf.e_phdr.e_phdr32 :
(void *) e->e_u.e_elf.e_phdr.e_phdr64)) != NULL)
return (phdr);
/*
* Check the PHDR related fields in the EHDR for sanity.
*/
if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL)
return (NULL);
phnum = e->e_u.e_elf.e_nphdr;
if (ec == ELFCLASS32) {
eh32 = (Elf32_Ehdr *) ehdr;
phentsize = eh32->e_phentsize;
phoff = (uint64_t) eh32->e_phoff;
} else {
eh64 = (Elf64_Ehdr *) ehdr;
phentsize = eh64->e_phentsize;
phoff = (uint64_t) eh64->e_phoff;
}
fsz = gelf_fsize(e, ELF_T_PHDR, phnum, e->e_version);
assert(fsz > 0);
if ((uint64_t) e->e_rawsize < (phoff + fsz)) {
LIBELF_SET_ERROR(HEADER, 0);
return (NULL);
}
msz = _libelf_msize(ELF_T_PHDR, ec, EV_CURRENT);
assert(msz > 0);
if ((phdr = calloc(phnum, msz)) == NULL) {
LIBELF_SET_ERROR(RESOURCE, 0);
return (NULL);
}
if (ec == ELFCLASS32)
e->e_u.e_elf.e_phdr.e_phdr32 = phdr;
else
e->e_u.e_elf.e_phdr.e_phdr64 = phdr;
xlator = _libelf_get_translator(ELF_T_PHDR, ELF_TOMEMORY, ec);
(*xlator)(phdr, e->e_rawfile + phoff, phnum,
e->e_byteorder != LIBELF_PRIVATE(byteorder));
return (phdr);
}
void *
_libelf_newphdr(Elf *e, int ec, size_t count)
{
void *ehdr, *newphdr, *oldphdr;
size_t msz;
if (e == NULL) {
LIBELF_SET_ERROR(ARGUMENT, 0);
return (NULL);
}
if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL) {
LIBELF_SET_ERROR(SEQUENCE, 0);
return (NULL);
}
assert(e->e_class == ec);
assert(ec == ELFCLASS32 || ec == ELFCLASS64);
assert(e->e_version == EV_CURRENT);
msz = _libelf_msize(ELF_T_PHDR, ec, e->e_version);
assert(msz > 0);
newphdr = NULL;
if (count > 0 && (newphdr = calloc(count, msz)) == NULL) {
LIBELF_SET_ERROR(RESOURCE, 0);
return (NULL);
}
if (ec == ELFCLASS32) {
if ((oldphdr = (void *) e->e_u.e_elf.e_phdr.e_phdr32) != NULL)
free(oldphdr);
e->e_u.e_elf.e_phdr.e_phdr32 = (Elf32_Phdr *) newphdr;
} else {
if ((oldphdr = (void *) e->e_u.e_elf.e_phdr.e_phdr64) != NULL)
free(oldphdr);
e->e_u.e_elf.e_phdr.e_phdr64 = (Elf64_Phdr *) newphdr;
}
e->e_u.e_elf.e_nphdr = count;
elf_flagphdr(e, ELF_C_SET, ELF_F_DIRTY);
return (newphdr);
}