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 /* 23 * Copyright 2010 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */ 28 /* All Rights Reserved */ 29 30 /* Copyright (c) 1987, 1988 Microsoft Corporation */ 31 /* All Rights Reserved */ 32 33 34 #include <errno.h> 35 #include <libelf.h> 36 #include "decl.h" 37 #include "msg.h" 38 39 /* 40 * Routines for generating a checksum for an elf image. Typically used to create 41 * a DT_CHECKSUM entry. This checksum is intended to remain constant after 42 * operations such as strip(1)/mcs(1), thus only allocatable sections are 43 * processed, and of those, any that might be modified by these external 44 * commands are skipped. 45 */ 46 #define MSW(l) (((l) >> 16) & 0x0000ffffL) 47 #define LSW(l) ((l) & 0x0000ffffL) 48 49 50 /* 51 * update and epilogue sum functions (stolen from libcmd) 52 */ 53 static long 54 sumupd(long sum, char *cp, unsigned long cnt) 55 { 56 if ((cp == 0) || (cnt == 0)) 57 return (sum); 58 59 while (cnt--) 60 sum += *cp++ & 0x00ff; 61 62 return (sum); 63 } 64 65 static long 66 sumepi(long sum) 67 { 68 long _sum; 69 70 _sum = LSW(sum) + MSW(sum); 71 return ((ushort_t)(LSW(_sum) + MSW(_sum))); 72 } 73 74 /* 75 * This module is compiled twice, the second time having 76 * -D_ELF64 defined. The following set of macros represent 77 * the differences between the two compilations. Be 78 * careful *not* to add any class dependent code (anything 79 * that has elf32 or elf64 in the name) to this code 80 * without hiding it behind a switchable macro like these. 81 */ 82 #if defined(_ELF64) 83 84 #define elf_checksum elf64_checksum 85 #define Elf_Ehdr Elf64_Ehdr 86 #define Elf_Shdr Elf64_Shdr 87 #define getehdr elf64_getehdr 88 #define getshdr elf64_getshdr 89 90 #else /* else ELF32 */ 91 92 #define elf_checksum elf32_checksum 93 #define Elf_Ehdr Elf32_Ehdr 94 #define Elf_Shdr Elf32_Shdr 95 #define getehdr elf32_getehdr 96 #define getshdr elf32_getshdr 97 98 #endif /* ELF64 */ 99 100 long 101 elf_checksum(Elf * elf) 102 { 103 long sum = 0; 104 Elf_Ehdr * ehdr; 105 Elf_Shdr * shdr; 106 Elf_Scn * scn; 107 Elf_Data * data, * (* getdata)(Elf_Scn *, Elf_Data *); 108 size_t shnum; 109 110 if ((ehdr = getehdr(elf)) == 0) 111 return (0); 112 113 /* 114 * Determine the data information to retrieve. When called from ld() 115 * we're processing an ELF_C_IMAGE (memory) image and thus need to use 116 * elf_getdata(), as there is not yet a file image (or raw data) backing 117 * this. When called from utilities like elfdump(1) we're processing a 118 * file image and thus using the elf_rawdata() allows the same byte 119 * stream to be processed from different architectures - presently this 120 * is irrelevant, as the checksum simply sums the data bytes, their 121 * order doesn't matter. But being uncooked is slightly less overhead. 122 * 123 * If the file is writable, the raw data will not reflect any 124 * changes made in the process, so the uncooked version is only 125 * for readonly files. 126 */ 127 if ((elf->ed_myflags & (EDF_MEMORY | EDF_WRITE)) != 0) 128 getdata = elf_getdata; 129 else 130 getdata = elf_rawdata; 131 132 for (shnum = 1; shnum < ehdr->e_shnum; shnum++) { 133 if ((scn = elf_getscn(elf, shnum)) == 0) 134 return (0); 135 if ((shdr = getshdr(scn)) == 0) 136 return (0); 137 138 /* Exclude strippable sections */ 139 if (!(shdr->sh_flags & SHF_ALLOC)) 140 continue; 141 142 /* 143 * Exclude allocable sections that can change: 144 * - The .dynsym section can contain section symbols 145 * that strip might remove. 146 * - The .dynamic section is modified by the setting of 147 * this checksum value. 148 * - The .SUNW_dof section uses ftok(3C), which returns 149 * different values, to define a key for the 150 * objects in that section. 151 */ 152 if ((shdr->sh_type == SHT_DYNSYM) || 153 (shdr->sh_type == SHT_DYNAMIC) || 154 (shdr->sh_type == SHT_SUNW_dof)) 155 continue; 156 157 data = 0; 158 while ((data = (*getdata)(scn, data)) != 0) 159 sum = sumupd(sum, data->d_buf, data->d_size); 160 161 } 162 return (sumepi(sum)); 163 } 164