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