1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* 22 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */ 27 /* All Rights Reserved */ 28 29 /* Copyright (c) 1987, 1988 Microsoft Corporation */ 30 /* All Rights Reserved */ 31 32 #pragma ident "%Z%%M% %I% %E% SMI" 33 34 #include "syn.h" 35 #include <errno.h> 36 #include <libelf.h> 37 #include "decl.h" 38 #include "msg.h" 39 40 /* 41 * Routines for generating a checksum for an elf image. Typically used to create 42 * a DT_CHECKSUM entry. This checksum is intended to remain constant after 43 * operations such as strip(1)/mcs(1), thus only allocatable sections are 44 * processed, and of those, any that might be modified by these external 45 * commands are skipped. 46 */ 47 #define MSW(l) (((l) >> 16) & 0x0000ffffL) 48 #define LSW(l) ((l) & 0x0000ffffL) 49 50 51 /* 52 * update and epilogue sum functions (stolen from libcmd) 53 */ 54 static long 55 sumupd(long sum, char *cp, unsigned long cnt) 56 { 57 if ((cp == 0) || (cnt == 0)) 58 return (sum); 59 60 while (cnt--) 61 sum += *cp++ & 0x00ff; 62 63 return (sum); 64 } 65 66 static long 67 sumepi(long sum) 68 { 69 long _sum; 70 71 _sum = LSW(sum) + MSW(sum); 72 return ((ushort_t)(LSW(_sum) + MSW(_sum))); 73 } 74 75 long 76 elf32_checksum(Elf * elf) 77 { 78 long sum = 0; 79 Elf32_Ehdr * ehdr; 80 Elf32_Shdr * shdr; 81 Elf_Scn * scn; 82 Elf_Data * data, * (* getdata)(Elf_Scn *, Elf_Data *); 83 size_t shnum; 84 85 if ((ehdr = elf32_getehdr(elf)) == 0) 86 return (0); 87 88 /* 89 * Determine the data information to retrieve. When called from ld() 90 * we're processing an ELF_C_IMAGE (memory) image and thus need to use 91 * elf_getdata(), as there is not yet a file image (or raw data) backing 92 * this. When called from utilities like elfdump(1) we're processing a 93 * file image and thus using the elf_rawdata() allows the same byte 94 * stream to be processed from different architectures - presently this 95 * is irrelevant, as the checksum simply sums the data bytes, their 96 * order doesn't matter. But being uncooked is slightly less overhead. 97 */ 98 if (elf->ed_myflags & EDF_MEMORY) 99 getdata = elf_getdata; 100 else 101 getdata = elf_rawdata; 102 103 for (shnum = 1; shnum < ehdr->e_shnum; shnum++) { 104 if ((scn = elf_getscn(elf, shnum)) == 0) 105 return (0); 106 if ((shdr = elf32_getshdr(scn)) == 0) 107 return (0); 108 109 if (!(shdr->sh_flags & SHF_ALLOC)) 110 continue; 111 112 if ((shdr->sh_type == SHT_DYNSYM) || 113 (shdr->sh_type == SHT_DYNAMIC)) 114 continue; 115 116 data = 0; 117 while ((data = (*getdata)(scn, data)) != 0) 118 sum = sumupd(sum, data->d_buf, data->d_size); 119 120 } 121 return (sumepi(sum)); 122 } 123 124 long 125 elf64_checksum(Elf * elf) 126 { 127 long sum = 0; 128 Elf64_Ehdr * ehdr; 129 Elf64_Shdr * shdr; 130 Elf_Scn * scn; 131 Elf_Data * data; 132 size_t shnum; 133 134 if ((ehdr = elf64_getehdr(elf)) == 0) 135 return (0); 136 137 for (shnum = 1; shnum < ehdr->e_shnum; shnum++) { 138 if ((scn = elf_getscn(elf, shnum)) == 0) 139 return (0); 140 if ((shdr = elf64_getshdr(scn)) == 0) 141 return (0); 142 143 /* Exclude strippable sections */ 144 if (!(shdr->sh_flags & SHF_ALLOC)) 145 continue; 146 147 /* 148 * Exclude allocable sections that can change: 149 * - The .dynsym section can contain section symbols 150 * that strip might remove. 151 * - The .dynamic section is modified by the setting of 152 * this checksum value. 153 */ 154 if ((shdr->sh_type == SHT_DYNSYM) || 155 (shdr->sh_type == SHT_DYNAMIC)) 156 continue; 157 158 data = 0; 159 while ((data = elf_getdata(scn, data)) != 0) 160 sum = sumupd(sum, data->d_buf, data->d_size); 161 162 } 163 return (sumepi(sum)); 164 } 165