1/* $NetBSD: exec_aout.c,v 1.6 1997/08/02 21:30:17 perry Exp $ */ 2/* 3 * Copyright (c) 1997 Christopher G. Demetriou. All rights reserved. 4 * Copyright (c) 1994 University of Maryland 5 * All Rights Reserved. 6 * 7 * Permission to use, copy, modify, distribute, and sell this software and its 8 * documentation for any purpose is hereby granted without fee, provided that 9 * the above copyright notice appear in all copies and that both that 10 * copyright notice and this permission notice appear in supporting 11 * documentation, and that the name of U.M. not be used in advertising or 12 * publicity pertaining to distribution of the software without specific, 13 * written prior permission. U.M. makes no representations about the 14 * suitability of this software for any purpose. It is provided "as is" 15 * without express or implied warranty. 16 * 17 * U.M. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL U.M. 19 * BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 20 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 21 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 22 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 23 * 24 * Author: James da Silva, Systems Design and Analysis Group 25 * Computer Science Department 26 * University of Maryland at College Park 27 */ 28#include <sys/cdefs.h> 29#ifndef lint 30__RCSID("$NetBSD: exec_aout.c,v 1.6 1997/08/02 21:30:17 perry Exp $"); 31__FBSDID("$FreeBSD: releng/10.2/usr.sbin/crunch/crunchide/exec_aout.c 130927 2004-06-22 17:05:39Z obrien $"); 32#endif 33 34#include <unistd.h> 35#include <stdio.h> 36#include <stdlib.h> 37#include <string.h> 38#include <a.out.h> 39#include <sys/types.h> 40#include <sys/endian.h> 41#include <sys/stat.h> 42#include <sys/errno.h> 43#include <netinet/in.h> 44 45#include "extern.h" 46 47#if defined(NLIST_AOUT) 48 49int nsyms, ntextrel, ndatarel; 50struct exec *hdrp; 51char *aoutdata, *strbase; 52struct relocation_info *textrel, *datarel; 53struct nlist *symbase; 54 55 56#define SYMSTR(sp) (&strbase[(sp)->n_un.n_strx]) 57 58/* is the symbol a global symbol defined in the current file? */ 59#define IS_GLOBAL_DEFINED(sp) \ 60 (((sp)->n_type & N_EXT) && ((sp)->n_type & N_TYPE) != N_UNDF) 61 62/* is the relocation entry dependent on a symbol? */ 63#define IS_SYMBOL_RELOC(rp) \ 64 ((rp)->r_extern||(rp)->r_baserel||(rp)->r_jmptable) 65 66static void check_reloc(const char *filename, struct relocation_info *relp); 67 68int check_aout(int inf, const char *filename) 69{ 70 struct stat infstat; 71 struct exec eh; 72 73 /* 74 * check the header to make sure it's an a.out-format file. 75 */ 76 77 if(fstat(inf, &infstat) == -1) 78 return 0; 79 if(infstat.st_size < sizeof eh) 80 return 0; 81 if(read(inf, &eh, sizeof eh) != sizeof eh) 82 return 0; 83 84 if(N_BADMAG(eh)) 85 return 0; 86 87 return 1; 88} 89 90int hide_aout(int inf, const char *filename) 91{ 92 struct stat infstat; 93 struct relocation_info *relp; 94 struct nlist *symp; 95 int rc; 96 97 /* 98 * do some error checking. 99 */ 100 101 if(fstat(inf, &infstat) == -1) { 102 perror(filename); 103 return 1; 104 } 105 106 /* 107 * Read the entire file into memory. XXX - Really, we only need to 108 * read the header and from TRELOFF to the end of the file. 109 */ 110 111 if((aoutdata = (char *) malloc(infstat.st_size)) == NULL) { 112 fprintf(stderr, "%s: too big to read into memory\n", filename); 113 return 1; 114 } 115 116 if((rc = read(inf, aoutdata, infstat.st_size)) < infstat.st_size) { 117 fprintf(stderr, "%s: read error: %s\n", filename, 118 rc == -1? strerror(errno) : "short read"); 119 return 1; 120 } 121 122 /* 123 * Calculate offsets and sizes from the header. 124 */ 125 126 hdrp = (struct exec *) aoutdata; 127 128#ifdef __FreeBSD__ 129 textrel = (struct relocation_info *) (aoutdata + N_RELOFF(*hdrp)); 130 datarel = (struct relocation_info *) (aoutdata + N_RELOFF(*hdrp) + 131 hdrp->a_trsize); 132#else 133 textrel = (struct relocation_info *) (aoutdata + N_TRELOFF(*hdrp)); 134 datarel = (struct relocation_info *) (aoutdata + N_DRELOFF(*hdrp)); 135#endif 136 symbase = (struct nlist *) (aoutdata + N_SYMOFF(*hdrp)); 137 strbase = (char *) (aoutdata + N_STROFF(*hdrp)); 138 139 ntextrel = hdrp->a_trsize / sizeof(struct relocation_info); 140 ndatarel = hdrp->a_drsize / sizeof(struct relocation_info); 141 nsyms = hdrp->a_syms / sizeof(struct nlist); 142 143 /* 144 * Zap the type field of all globally-defined symbols. The linker will 145 * subsequently ignore these entries. Don't zap any symbols in the 146 * keep list. 147 */ 148 149 for(symp = symbase; symp < symbase + nsyms; symp++) { 150 if(!IS_GLOBAL_DEFINED(symp)) /* keep undefined syms */ 151 continue; 152 153 /* keep (C) symbols which are on the keep list */ 154 if(SYMSTR(symp)[0] == '_' && in_keep_list(SYMSTR(symp) + 1)) 155 continue; 156 157 symp->n_type = 0; 158 } 159 160 /* 161 * Check whether the relocation entries reference any symbols that we 162 * just zapped. I don't know whether ld can handle this case, but I 163 * haven't encountered it yet. These checks are here so that the program 164 * doesn't fail silently should such symbols be encountered. 165 */ 166 167 for(relp = textrel; relp < textrel + ntextrel; relp++) 168 check_reloc(filename, relp); 169 for(relp = datarel; relp < datarel + ndatarel; relp++) 170 check_reloc(filename, relp); 171 172 /* 173 * Write the .o file back out to disk. XXX - Really, we only need to 174 * write the symbol table entries back out. 175 */ 176 lseek(inf, 0, SEEK_SET); 177 if((rc = write(inf, aoutdata, infstat.st_size)) < infstat.st_size) { 178 fprintf(stderr, "%s: write error: %s\n", filename, 179 rc == -1? strerror(errno) : "short write"); 180 return 1; 181 } 182 183 return 0; 184} 185 186 187static void check_reloc(const char *filename, struct relocation_info *relp) 188{ 189 /* bail out if we zapped a symbol that is needed */ 190 if(IS_SYMBOL_RELOC(relp) && symbase[relp->r_symbolnum].n_type == 0) { 191 fprintf(stderr, 192 "%s: oops, have hanging relocation for %s: bailing out!\n", 193 filename, SYMSTR(&symbase[relp->r_symbolnum])); 194 exit(1); 195 } 196} 197 198#endif /* defined(NLIST_AOUT) */ 199