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 the file is writable, the raw data will not reflect any 99 * changes made in the process, so the uncooked version is only 100 * for readonly files. 101 */ 102 if ((elf->ed_myflags & (EDF_MEMORY | EDF_WRITE)) != 0) 103 getdata = elf_getdata; 104 else 105 getdata = elf_rawdata; 106 107 for (shnum = 1; shnum < ehdr->e_shnum; shnum++) { 108 if ((scn = elf_getscn(elf, shnum)) == 0) 109 return (0); 110 if ((shdr = elf32_getshdr(scn)) == 0) 111 return (0); 112 113 if (!(shdr->sh_flags & SHF_ALLOC)) 114 continue; 115 116 if ((shdr->sh_type == SHT_DYNSYM) || 117 (shdr->sh_type == SHT_DYNAMIC)) 118 continue; 119 120 data = 0; 121 while ((data = (*getdata)(scn, data)) != 0) 122 sum = sumupd(sum, data->d_buf, data->d_size); 123 124 } 125 return (sumepi(sum)); 126 } 127 128 long 129 elf64_checksum(Elf * elf) 130 { 131 long sum = 0; 132 Elf64_Ehdr * ehdr; 133 Elf64_Shdr * shdr; 134 Elf_Scn * scn; 135 Elf_Data * data; 136 size_t shnum; 137 138 if ((ehdr = elf64_getehdr(elf)) == 0) 139 return (0); 140 141 for (shnum = 1; shnum < ehdr->e_shnum; shnum++) { 142 if ((scn = elf_getscn(elf, shnum)) == 0) 143 return (0); 144 if ((shdr = elf64_getshdr(scn)) == 0) 145 return (0); 146 147 /* Exclude strippable sections */ 148 if (!(shdr->sh_flags & SHF_ALLOC)) 149 continue; 150 151 /* 152 * Exclude allocable sections that can change: 153 * - The .dynsym section can contain section symbols 154 * that strip might remove. 155 * - The .dynamic section is modified by the setting of 156 * this checksum value. 157 */ 158 if ((shdr->sh_type == SHT_DYNSYM) || 159 (shdr->sh_type == SHT_DYNAMIC)) 160 continue; 161 162 data = 0; 163 while ((data = elf_getdata(scn, data)) != 0) 164 sum = sumupd(sum, data->d_buf, data->d_size); 165 166 } 167 return (sumepi(sum)); 168 } 169