1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 2000, 2001 David O'Brien 5 * Copyright (c) 1996 Søren Schmidt 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer 13 * in this position and unchanged. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. The name of the author may not be used to endorse or promote products 18 * derived from this software without specific prior written permission 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 23 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <sys/param.h> 33 #include <sys/capsicum.h> 34 #include <sys/elf_common.h> 35 #include <sys/errno.h> 36 37 #include <capsicum_helpers.h> 38 #include <err.h> 39 #include <fcntl.h> 40 #include <stdbool.h> 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include <string.h> 44 #include <unistd.h> 45 46 #include <libcasper.h> 47 #include <casper/cap_fileargs.h> 48 49 static int elftype(const char *); 50 static const char *iselftype(int); 51 static void printelftypes(void); 52 static void usage(void) __dead2; 53 54 struct ELFtypes { 55 const char *str; 56 int value; 57 }; 58 /* XXX - any more types? */ 59 static struct ELFtypes elftypes[] = { 60 { "FreeBSD", ELFOSABI_FREEBSD }, 61 { "Linux", ELFOSABI_LINUX }, 62 { "Solaris", ELFOSABI_SOLARIS }, 63 { "SVR4", ELFOSABI_SYSV } 64 }; 65 66 int 67 main(int argc, char **argv) 68 { 69 70 const char *strtype = "FreeBSD"; 71 int ch, flags, retval, type; 72 bool change, force, listed; 73 fileargs_t *fa; 74 cap_rights_t rights; 75 76 type = ELFOSABI_FREEBSD; 77 retval = 0; 78 change = false; 79 force = false; 80 listed = false; 81 82 while ((ch = getopt(argc, argv, "f:lt:v")) != -1) 83 switch (ch) { 84 case 'f': 85 if (change) 86 errx(1, "f option incompatible with t option"); 87 force = true; 88 type = atoi(optarg); 89 if (errno == ERANGE || type < 0 || type > 255) { 90 warnx("invalid argument to option f: %s", 91 optarg); 92 usage(); 93 } 94 break; 95 case 'l': 96 printelftypes(); 97 listed = true; 98 break; 99 case 'v': 100 /* does nothing */ 101 break; 102 case 't': 103 if (force) 104 errx(1, "t option incompatible with f option"); 105 change = true; 106 strtype = optarg; 107 break; 108 default: 109 usage(); 110 } 111 argc -= optind; 112 argv += optind; 113 if (argc == 0) { 114 if (listed) 115 exit(0); 116 else { 117 warnx("no file(s) specified"); 118 usage(); 119 } 120 } 121 122 if (!force && (type = elftype(strtype)) == -1) { 123 warnx("invalid ELF type '%s'", strtype); 124 printelftypes(); 125 usage(); 126 } 127 128 flags = change || force ? O_RDWR : O_RDONLY; 129 cap_rights_init(&rights, CAP_READ, CAP_SEEK); 130 if (flags == O_RDWR) 131 cap_rights_set(&rights, CAP_WRITE); 132 133 fa = fileargs_init(argc, argv, flags, 0, &rights, FA_OPEN); 134 if (fa == NULL) 135 err(1, "unable to init casper"); 136 137 caph_cache_catpages(); 138 if (caph_limit_stdio() < 0 || caph_enter_casper() < 0) 139 err(1, "unable to enter capability mode"); 140 141 while (argc != 0) { 142 int fd; 143 char buffer[EI_NIDENT]; 144 145 if ((fd = fileargs_open(fa, argv[0])) < 0) { 146 warn("error opening file %s", argv[0]); 147 retval = 1; 148 goto fail; 149 } 150 if (read(fd, buffer, EI_NIDENT) < EI_NIDENT) { 151 warnx("file '%s' too short", argv[0]); 152 retval = 1; 153 goto fail; 154 } 155 if (buffer[0] != ELFMAG0 || buffer[1] != ELFMAG1 || 156 buffer[2] != ELFMAG2 || buffer[3] != ELFMAG3) { 157 warnx("file '%s' is not ELF format", argv[0]); 158 retval = 1; 159 goto fail; 160 } 161 if (!change && !force) { 162 fprintf(stdout, 163 "File '%s' is of brand '%s' (%u).\n", 164 argv[0], iselftype(buffer[EI_OSABI]), 165 buffer[EI_OSABI]); 166 if (!iselftype(type)) { 167 warnx("ELF ABI Brand '%u' is unknown", 168 type); 169 printelftypes(); 170 } 171 } 172 else { 173 buffer[EI_OSABI] = type; 174 lseek(fd, 0, SEEK_SET); 175 if (write(fd, buffer, EI_NIDENT) != EI_NIDENT) { 176 warn("error writing %s %d", argv[0], fd); 177 retval = 1; 178 goto fail; 179 } 180 } 181 fail: 182 close(fd); 183 argc--; 184 argv++; 185 } 186 187 fileargs_free(fa); 188 return (retval); 189 } 190 191 static void 192 usage(void) 193 { 194 (void)fprintf(stderr, 195 "usage: brandelf [-lv] [-f ELF_ABI_number] [-t string] file ...\n"); 196 exit(1); 197 } 198 199 static const char * 200 iselftype(int etype) 201 { 202 size_t elfwalk; 203 204 for (elfwalk = 0; elfwalk < nitems(elftypes); elfwalk++) 205 if (etype == elftypes[elfwalk].value) 206 return (elftypes[elfwalk].str); 207 return (0); 208 } 209 210 static int 211 elftype(const char *elfstrtype) 212 { 213 size_t elfwalk; 214 215 for (elfwalk = 0; elfwalk < nitems(elftypes); elfwalk++) 216 if (strcasecmp(elfstrtype, elftypes[elfwalk].str) == 0) 217 return (elftypes[elfwalk].value); 218 return (-1); 219 } 220 221 static void 222 printelftypes(void) 223 { 224 size_t elfwalk; 225 226 fprintf(stderr, "known ELF types are: "); 227 for (elfwalk = 0; elfwalk < nitems(elftypes); elfwalk++) 228 fprintf(stderr, "%s(%u) ", elftypes[elfwalk].str, 229 elftypes[elfwalk].value); 230 fprintf(stderr, "\n"); 231 } 232