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freebsd/lib/libelf/libelf_extended.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

137 lines
3.2 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <assert.h>
#include <libelf.h>
#include "_libelf.h"
/*
* Retrieve section #0, allocating a new section if needed.
*/
static Elf_Scn *
_libelf_getscn0(Elf *e)
{
Elf_Scn *s;
if ((s = STAILQ_FIRST(&e->e_u.e_elf.e_scn)) != NULL)
return (s);
return (_libelf_allocate_scn(e, (size_t) SHN_UNDEF));
}
int
_libelf_setshnum(Elf *e, void *eh, int ec, size_t shnum)
{
Elf_Scn *scn;
if (shnum >= SHN_LORESERVE) {
if ((scn = _libelf_getscn0(e)) == NULL)
return (0);
assert(scn->s_ndx == SHN_UNDEF);
if (ec == ELFCLASS32)
scn->s_shdr.s_shdr32.sh_size = shnum;
else
scn->s_shdr.s_shdr64.sh_size = shnum;
(void) elf_flagshdr(scn, ELF_C_SET, ELF_F_DIRTY);
shnum = 0;
}
if (ec == ELFCLASS32)
((Elf32_Ehdr *) eh)->e_shnum = shnum;
else
((Elf64_Ehdr *) eh)->e_shnum = shnum;
return (1);
}
int
_libelf_setshstrndx(Elf *e, void *eh, int ec, size_t shstrndx)
{
Elf_Scn *scn;
if (shstrndx >= SHN_LORESERVE) {
if ((scn = _libelf_getscn0(e)) == NULL)
return (0);
assert(scn->s_ndx == SHN_UNDEF);
if (ec == ELFCLASS32)
scn->s_shdr.s_shdr32.sh_link = shstrndx;
else
scn->s_shdr.s_shdr64.sh_link = shstrndx;
(void) elf_flagshdr(scn, ELF_C_SET, ELF_F_DIRTY);
shstrndx = SHN_XINDEX;
}
if (ec == ELFCLASS32)
((Elf32_Ehdr *) eh)->e_shstrndx = shstrndx;
else
((Elf64_Ehdr *) eh)->e_shstrndx = shstrndx;
return (1);
}
int
_libelf_setphnum(Elf *e, void *eh, int ec, size_t phnum)
{
Elf_Scn *scn;
if (phnum >= PN_XNUM) {
if ((scn = _libelf_getscn0(e)) == NULL)
return (0);
assert(scn->s_ndx == SHN_UNDEF);
if (ec == ELFCLASS32)
scn->s_shdr.s_shdr32.sh_info = phnum;
else
scn->s_shdr.s_shdr64.sh_info = phnum;
(void) elf_flagshdr(scn, ELF_C_SET, ELF_F_DIRTY);
phnum = PN_XNUM;
}
if (ec == ELFCLASS32)
((Elf32_Ehdr *) eh)->e_phnum = phnum;
else
((Elf64_Ehdr *) eh)->e_phnum = phnum;
return (1);
}