1/* $NetBSD: libelf_checksum.c,v 1.5 2024/03/03 17:37:34 christos Exp $ */ 2 3/*- 4 * Copyright (c) 2006,2008 Joseph Koshy 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29#include <sys/cdefs.h> 30 31#include <gelf.h> 32 33#include "_libelf.h" 34 35__RCSID("$NetBSD: libelf_checksum.c,v 1.5 2024/03/03 17:37:34 christos Exp $"); 36ELFTC_VCSID("Id: libelf_checksum.c 3977 2022-05-01 06:45:34Z jkoshy"); 37 38static unsigned long 39_libelf_sum(unsigned long c, const unsigned char *s, size_t size) 40{ 41 if (s == NULL || size == 0) 42 return (c); 43 44 while (size--) 45 c += *s++; 46 47 return (c); 48} 49 50long 51_libelf_checksum(Elf *e, int elfclass) 52{ 53 size_t shn; 54 Elf_Scn *scn; 55 Elf_Data *d; 56 unsigned long checksum; 57 GElf_Ehdr eh; 58 GElf_Shdr shdr; 59 60 if (e == NULL) { 61 LIBELF_SET_ERROR(ARGUMENT, 0); 62 return (0L); 63 } 64 65 if (e->e_class != elfclass) { 66 LIBELF_SET_ERROR(CLASS, 0); 67 return (0L); 68 } 69 70 if (gelf_getehdr(e, &eh) == NULL) 71 return (0); 72 73 /* 74 * Iterate over all sections in the ELF file, computing the 75 * checksum along the way. 76 * 77 * The first section is always SHN_UNDEF and can be skipped. 78 * Non-allocatable sections are skipped, as are sections that 79 * could be affected by utilities such as strip(1). 80 */ 81 82 checksum = 0; 83 for (shn = 1; shn < e->e_u.e_elf.e_nscn; shn++) { 84 if ((scn = elf_getscn(e, shn)) == NULL) 85 return (0); 86 if (gelf_getshdr(scn, &shdr) == NULL) 87 return (0); 88 if ((shdr.sh_flags & SHF_ALLOC) == 0 || 89 shdr.sh_type == SHT_DYNAMIC || 90 shdr.sh_type == SHT_DYNSYM) 91 continue; 92 93 d = NULL; 94 while ((d = elf_rawdata(scn, d)) != NULL) 95 checksum = _libelf_sum(checksum, 96 (unsigned char *) d->d_buf, (size_t) d->d_size); 97 } 98 99 /* 100 * Return a 16-bit checksum compatible with Solaris. 101 */ 102 return (long) (((checksum >> 16) & 0xFFFFUL) + (checksum & 0xFFFFUL)); 103} 104