1*0a6a1f1dSLionel Sambuc /* $NetBSD: libelf_checksum.c,v 1.2 2014/03/09 16:58:04 christos Exp $ */
2*0a6a1f1dSLionel Sambuc
3*0a6a1f1dSLionel Sambuc /*-
4*0a6a1f1dSLionel Sambuc * Copyright (c) 2006,2008 Joseph Koshy
5*0a6a1f1dSLionel Sambuc * All rights reserved.
6*0a6a1f1dSLionel Sambuc *
7*0a6a1f1dSLionel Sambuc * Redistribution and use in source and binary forms, with or without
8*0a6a1f1dSLionel Sambuc * modification, are permitted provided that the following conditions
9*0a6a1f1dSLionel Sambuc * are met:
10*0a6a1f1dSLionel Sambuc * 1. Redistributions of source code must retain the above copyright
11*0a6a1f1dSLionel Sambuc * notice, this list of conditions and the following disclaimer.
12*0a6a1f1dSLionel Sambuc * 2. Redistributions in binary form must reproduce the above copyright
13*0a6a1f1dSLionel Sambuc * notice, this list of conditions and the following disclaimer in the
14*0a6a1f1dSLionel Sambuc * documentation and/or other materials provided with the distribution.
15*0a6a1f1dSLionel Sambuc *
16*0a6a1f1dSLionel Sambuc * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17*0a6a1f1dSLionel Sambuc * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18*0a6a1f1dSLionel Sambuc * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19*0a6a1f1dSLionel Sambuc * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20*0a6a1f1dSLionel Sambuc * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21*0a6a1f1dSLionel Sambuc * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22*0a6a1f1dSLionel Sambuc * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23*0a6a1f1dSLionel Sambuc * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24*0a6a1f1dSLionel Sambuc * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25*0a6a1f1dSLionel Sambuc * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26*0a6a1f1dSLionel Sambuc * SUCH DAMAGE.
27*0a6a1f1dSLionel Sambuc */
28*0a6a1f1dSLionel Sambuc
29*0a6a1f1dSLionel Sambuc #include <sys/cdefs.h>
30*0a6a1f1dSLionel Sambuc
31*0a6a1f1dSLionel Sambuc #include <gelf.h>
32*0a6a1f1dSLionel Sambuc
33*0a6a1f1dSLionel Sambuc #include "_libelf.h"
34*0a6a1f1dSLionel Sambuc
35*0a6a1f1dSLionel Sambuc __RCSID("$NetBSD: libelf_checksum.c,v 1.2 2014/03/09 16:58:04 christos Exp $");
36*0a6a1f1dSLionel Sambuc ELFTC_VCSID("Id: libelf_checksum.c 2225 2011-11-26 18:55:54Z jkoshy ");
37*0a6a1f1dSLionel Sambuc
38*0a6a1f1dSLionel Sambuc static unsigned long
_libelf_sum(unsigned long c,const unsigned char * s,size_t size)39*0a6a1f1dSLionel Sambuc _libelf_sum(unsigned long c, const unsigned char *s, size_t size)
40*0a6a1f1dSLionel Sambuc {
41*0a6a1f1dSLionel Sambuc if (s == NULL || size == 0)
42*0a6a1f1dSLionel Sambuc return (c);
43*0a6a1f1dSLionel Sambuc
44*0a6a1f1dSLionel Sambuc while (size--)
45*0a6a1f1dSLionel Sambuc c += *s++;
46*0a6a1f1dSLionel Sambuc
47*0a6a1f1dSLionel Sambuc return (c);
48*0a6a1f1dSLionel Sambuc }
49*0a6a1f1dSLionel Sambuc
50*0a6a1f1dSLionel Sambuc unsigned long
_libelf_checksum(Elf * e,int elfclass)51*0a6a1f1dSLionel Sambuc _libelf_checksum(Elf *e, int elfclass)
52*0a6a1f1dSLionel Sambuc {
53*0a6a1f1dSLionel Sambuc size_t shn;
54*0a6a1f1dSLionel Sambuc Elf_Scn *scn;
55*0a6a1f1dSLionel Sambuc Elf_Data *d;
56*0a6a1f1dSLionel Sambuc unsigned long checksum;
57*0a6a1f1dSLionel Sambuc GElf_Ehdr eh;
58*0a6a1f1dSLionel Sambuc GElf_Shdr shdr;
59*0a6a1f1dSLionel Sambuc
60*0a6a1f1dSLionel Sambuc if (e == NULL) {
61*0a6a1f1dSLionel Sambuc LIBELF_SET_ERROR(ARGUMENT, 0);
62*0a6a1f1dSLionel Sambuc return (0L);
63*0a6a1f1dSLionel Sambuc }
64*0a6a1f1dSLionel Sambuc
65*0a6a1f1dSLionel Sambuc if (e->e_class != elfclass) {
66*0a6a1f1dSLionel Sambuc LIBELF_SET_ERROR(CLASS, 0);
67*0a6a1f1dSLionel Sambuc return (0L);
68*0a6a1f1dSLionel Sambuc }
69*0a6a1f1dSLionel Sambuc
70*0a6a1f1dSLionel Sambuc if (gelf_getehdr(e, &eh) == NULL)
71*0a6a1f1dSLionel Sambuc return (0);
72*0a6a1f1dSLionel Sambuc
73*0a6a1f1dSLionel Sambuc /*
74*0a6a1f1dSLionel Sambuc * Iterate over all sections in the ELF file, computing the
75*0a6a1f1dSLionel Sambuc * checksum along the way.
76*0a6a1f1dSLionel Sambuc *
77*0a6a1f1dSLionel Sambuc * The first section is always SHN_UNDEF and can be skipped.
78*0a6a1f1dSLionel Sambuc * Non-allocatable sections are skipped, as are sections that
79*0a6a1f1dSLionel Sambuc * could be affected by utilities such as strip(1).
80*0a6a1f1dSLionel Sambuc */
81*0a6a1f1dSLionel Sambuc
82*0a6a1f1dSLionel Sambuc checksum = 0;
83*0a6a1f1dSLionel Sambuc for (shn = 1; shn < e->e_u.e_elf.e_nscn; shn++) {
84*0a6a1f1dSLionel Sambuc if ((scn = elf_getscn(e, shn)) == NULL)
85*0a6a1f1dSLionel Sambuc return (0);
86*0a6a1f1dSLionel Sambuc if (gelf_getshdr(scn, &shdr) == NULL)
87*0a6a1f1dSLionel Sambuc return (0);
88*0a6a1f1dSLionel Sambuc if ((shdr.sh_flags & SHF_ALLOC) == 0 ||
89*0a6a1f1dSLionel Sambuc shdr.sh_type == SHT_DYNAMIC ||
90*0a6a1f1dSLionel Sambuc shdr.sh_type == SHT_DYNSYM)
91*0a6a1f1dSLionel Sambuc continue;
92*0a6a1f1dSLionel Sambuc
93*0a6a1f1dSLionel Sambuc d = NULL;
94*0a6a1f1dSLionel Sambuc while ((d = elf_rawdata(scn, d)) != NULL)
95*0a6a1f1dSLionel Sambuc checksum = _libelf_sum(checksum,
96*0a6a1f1dSLionel Sambuc (unsigned char *) d->d_buf, d->d_size);
97*0a6a1f1dSLionel Sambuc }
98*0a6a1f1dSLionel Sambuc
99*0a6a1f1dSLionel Sambuc /*
100*0a6a1f1dSLionel Sambuc * Return a 16-bit checksum compatible with Solaris.
101*0a6a1f1dSLionel Sambuc */
102*0a6a1f1dSLionel Sambuc return (((checksum >> 16) & 0xFFFFUL) + (checksum & 0xFFFFUL));
103*0a6a1f1dSLionel Sambuc }
104