1 /*- 2 * Copyright (c) 2007 S.Sam Arun Raj 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/stat.h> 28 #include <sys/types.h> 29 30 #include <ctype.h> 31 #include <err.h> 32 #include <errno.h> 33 #include <fcntl.h> 34 #include <getopt.h> 35 #include <inttypes.h> 36 #include <stdint.h> 37 #include <stdio.h> 38 #include <stdlib.h> 39 #include <string.h> 40 #include <sysexits.h> 41 #include <unistd.h> 42 43 #include <libelf.h> 44 #include <libelftc.h> 45 #include <gelf.h> 46 47 #include "_elftc.h" 48 49 ELFTC_VCSID("$Id: strings.c 3571 2017-09-14 02:04:50Z emaste $"); 50 51 enum radix_style { 52 RADIX_DECIMAL, 53 RADIX_HEX, 54 RADIX_OCTAL 55 }; 56 57 enum encoding_style { 58 ENCODING_7BIT, 59 ENCODING_8BIT, 60 ENCODING_16BIT_BIG, 61 ENCODING_16BIT_LITTLE, 62 ENCODING_32BIT_BIG, 63 ENCODING_32BIT_LITTLE 64 }; 65 66 #define PRINTABLE(c) \ 67 ((c) >= 0 && (c) <= 255 && \ 68 ((c) == '\t' || isprint((c)) || \ 69 (encoding == ENCODING_8BIT && (c) > 127))) 70 71 static int encoding_size, entire_file, show_filename, show_loc; 72 static enum encoding_style encoding; 73 static enum radix_style radix; 74 static intmax_t min_len; 75 76 static struct option strings_longopts[] = { 77 { "all", no_argument, NULL, 'a'}, 78 { "bytes", required_argument, NULL, 'n'}, 79 { "encoding", required_argument, NULL, 'e'}, 80 { "help", no_argument, NULL, 'h'}, 81 { "print-file-name", no_argument, NULL, 'f'}, 82 { "radix", required_argument, NULL, 't'}, 83 { "version", no_argument, NULL, 'v'}, 84 { NULL, 0, NULL, 0 } 85 }; 86 87 long getcharacter(void); 88 int handle_file(const char *); 89 int handle_elf(const char *, int); 90 int handle_binary(const char *, int); 91 int find_strings(const char *, off_t, off_t); 92 void show_version(void); 93 void usage(void); 94 95 /* 96 * strings(1) extracts text(contiguous printable characters) 97 * from elf and binary files. 98 */ 99 int 100 main(int argc, char **argv) 101 { 102 int ch, rc; 103 104 rc = 0; 105 min_len = 0; 106 encoding_size = 1; 107 if (elf_version(EV_CURRENT) == EV_NONE) 108 errx(EXIT_FAILURE, "ELF library initialization failed: %s", 109 elf_errmsg(-1)); 110 111 while ((ch = getopt_long(argc, argv, "1234567890ae:fhn:ot:Vv", 112 strings_longopts, NULL)) != -1) 113 switch((char)ch) { 114 case 'a': 115 entire_file = 1; 116 break; 117 case 'e': 118 if (*optarg == 's') { 119 encoding = ENCODING_7BIT; 120 } else if (*optarg == 'S') { 121 encoding = ENCODING_8BIT; 122 } else if (*optarg == 'b') { 123 encoding = ENCODING_16BIT_BIG; 124 encoding_size = 2; 125 } else if (*optarg == 'B') { 126 encoding = ENCODING_32BIT_BIG; 127 encoding_size = 4; 128 } else if (*optarg == 'l') { 129 encoding = ENCODING_16BIT_LITTLE; 130 encoding_size = 2; 131 } else if (*optarg == 'L') { 132 encoding = ENCODING_32BIT_LITTLE; 133 encoding_size = 4; 134 } else 135 usage(); 136 /* NOTREACHED */ 137 break; 138 case 'f': 139 show_filename = 1; 140 break; 141 case 'n': 142 min_len = strtoimax(optarg, (char**)NULL, 10); 143 if (min_len <= 0) 144 errx(EX_USAGE, "option -n should specify a " 145 "positive decimal integer."); 146 break; 147 case 'o': 148 show_loc = 1; 149 radix = RADIX_OCTAL; 150 break; 151 case 't': 152 show_loc = 1; 153 if (*optarg == 'd') 154 radix = RADIX_DECIMAL; 155 else if (*optarg == 'o') 156 radix = RADIX_OCTAL; 157 else if (*optarg == 'x') 158 radix = RADIX_HEX; 159 else 160 usage(); 161 /* NOTREACHED */ 162 break; 163 case 'v': 164 case 'V': 165 show_version(); 166 /* NOTREACHED */ 167 case '0': 168 case '1': 169 case '2': 170 case '3': 171 case '4': 172 case '5': 173 case '6': 174 case '7': 175 case '8': 176 case '9': 177 min_len *= 10; 178 min_len += ch - '0'; 179 break; 180 case 'h': 181 case '?': 182 default: 183 usage(); 184 /* NOTREACHED */ 185 } 186 argc -= optind; 187 argv += optind; 188 189 if (!min_len) 190 min_len = 4; 191 if (!*argv) 192 rc = find_strings("{standard input}", 0, 0); 193 else while (*argv) { 194 if (handle_file(*argv) != 0) 195 rc = 1; 196 argv++; 197 } 198 return (rc); 199 } 200 201 int 202 handle_file(const char *name) 203 { 204 int fd, rt; 205 206 if (name == NULL) 207 return (1); 208 if (freopen(name, "rb", stdin) == NULL) { 209 warnx("'%s': %s", name, strerror(errno)); 210 return (1); 211 } 212 213 fd = fileno(stdin); 214 if (fd < 0) 215 return (1); 216 rt = handle_elf(name, fd); 217 return (rt); 218 } 219 220 /* 221 * Files not understood by handle_elf, will be passed off here and will 222 * treated as a binary file. This would include text file, core dumps ... 223 */ 224 int 225 handle_binary(const char *name, int fd) 226 { 227 struct stat buf; 228 229 memset(&buf, 0, sizeof(struct stat)); 230 (void) lseek(fd, (off_t)0, SEEK_SET); 231 if (!fstat(fd, &buf)) 232 return (find_strings(name, (off_t)0, buf.st_size)); 233 return (1); 234 } 235 236 /* 237 * Will analyse a file to see if it ELF, other files including ar(1), 238 * core dumps are passed off and treated as flat binary files. Unlike 239 * GNU size in FreeBSD this routine will not treat ELF object from 240 * different archs as flat binary files(has to overridden using -a). 241 */ 242 int 243 handle_elf(const char *name, int fd) 244 { 245 GElf_Ehdr elfhdr; 246 GElf_Shdr shdr; 247 Elf *elf; 248 Elf_Scn *scn; 249 int rc; 250 251 rc = 0; 252 /* If entire file is chosen, treat it as a binary file */ 253 if (entire_file) 254 return (handle_binary(name, fd)); 255 256 (void) lseek(fd, (off_t)0, SEEK_SET); 257 elf = elf_begin(fd, ELF_C_READ, NULL); 258 if (elf_kind(elf) != ELF_K_ELF) { 259 (void) elf_end(elf); 260 return (handle_binary(name, fd)); 261 } 262 263 if (gelf_getehdr(elf, &elfhdr) == NULL) { 264 (void) elf_end(elf); 265 warnx("%s: ELF file could not be processed", name); 266 return (1); 267 } 268 269 if (elfhdr.e_shnum == 0 && elfhdr.e_type == ET_CORE) { 270 (void) elf_end(elf); 271 return (handle_binary(name, fd)); 272 } else { 273 scn = NULL; 274 while ((scn = elf_nextscn(elf, scn)) != NULL) { 275 if (gelf_getshdr(scn, &shdr) == NULL) 276 continue; 277 if (shdr.sh_type != SHT_NOBITS && 278 (shdr.sh_flags & SHF_ALLOC) != 0) { 279 rc = find_strings(name, shdr.sh_offset, 280 shdr.sh_size); 281 } 282 } 283 } 284 (void) elf_end(elf); 285 return (rc); 286 } 287 288 /* 289 * Retrieves a character from input stream based on the encoding 290 * type requested. 291 */ 292 long 293 getcharacter(void) 294 { 295 long rt; 296 int i; 297 char buf[4], c; 298 299 rt = EOF; 300 for(i = 0; i < encoding_size; i++) { 301 c = getc(stdin); 302 if (feof(stdin)) 303 return (EOF); 304 buf[i] = c; 305 } 306 307 switch(encoding) { 308 case ENCODING_7BIT: 309 case ENCODING_8BIT: 310 rt = buf[0]; 311 break; 312 case ENCODING_16BIT_BIG: 313 rt = (buf[0] << 8) | buf[1]; 314 break; 315 case ENCODING_16BIT_LITTLE: 316 rt = buf[0] | (buf[1] << 8); 317 break; 318 case ENCODING_32BIT_BIG: 319 rt = ((long) buf[0] << 24) | ((long) buf[1] << 16) | 320 ((long) buf[2] << 8) | buf[3]; 321 break; 322 case ENCODING_32BIT_LITTLE: 323 rt = buf[0] | ((long) buf[1] << 8) | ((long) buf[2] << 16) | 324 ((long) buf[3] << 24); 325 break; 326 } 327 return (rt); 328 } 329 330 /* 331 * Input stream stdin is read until the end of file is reached or until 332 * the section size is reached in case of ELF files. Contiguous 333 * characters of >= min_size(default 4) will be displayed. 334 */ 335 int 336 find_strings(const char *name, off_t offset, off_t size) 337 { 338 off_t cur_off, start_off; 339 char *obuf; 340 long c; 341 int i; 342 343 if ((obuf = (char*)calloc(1, min_len + 1)) == NULL) { 344 (void) fprintf(stderr, "Unable to allocate memory: %s\n", 345 strerror(errno)); 346 return (1); 347 } 348 349 (void) fseeko(stdin, offset, SEEK_SET); 350 cur_off = offset; 351 start_off = 0; 352 while(1) { 353 if ((offset + size) && (cur_off >= offset + size)) 354 break; 355 start_off = cur_off; 356 memset(obuf, 0, min_len+1); 357 for(i = 0; i < min_len; i++) { 358 c = getcharacter(); 359 if (c == EOF && feof(stdin)) 360 goto _exit1; 361 if (PRINTABLE(c)) { 362 obuf[i] = c; 363 obuf[i+1] = 0; 364 cur_off += encoding_size; 365 } else { 366 if (encoding == ENCODING_8BIT && 367 (uint8_t)c > 127) { 368 obuf[i] = c; 369 obuf[i+1] = 0; 370 cur_off += encoding_size; 371 continue; 372 } 373 cur_off += encoding_size; 374 break; 375 } 376 } 377 378 if (i >= min_len && ((cur_off <= offset + size) || 379 !(offset + size))) { 380 if (show_filename) 381 printf ("%s: ", name); 382 if (show_loc) { 383 switch(radix) { 384 case RADIX_DECIMAL: 385 (void) printf("%7ju ", 386 (uintmax_t)start_off); 387 break; 388 case RADIX_HEX: 389 (void) printf("%7jx ", 390 (uintmax_t)start_off); 391 break; 392 case RADIX_OCTAL: 393 (void) printf("%7jo ", 394 (uintmax_t)start_off); 395 break; 396 } 397 } 398 printf("%s", obuf); 399 400 while(1) { 401 if ((offset + size) && 402 (cur_off >= offset + size)) 403 break; 404 c = getcharacter(); 405 cur_off += encoding_size; 406 if (encoding == ENCODING_8BIT && 407 (uint8_t)c > 127) { 408 putchar(c); 409 continue; 410 } 411 if (!PRINTABLE(c) || c == EOF) 412 break; 413 putchar(c); 414 } 415 putchar('\n'); 416 } 417 } 418 _exit1: 419 free(obuf); 420 return (0); 421 } 422 423 #define USAGE_MESSAGE "\ 424 Usage: %s [options] [file...]\n\ 425 Print contiguous sequences of printable characters.\n\n\ 426 Options:\n\ 427 -a | --all Scan the entire file for strings.\n\ 428 -e ENC | --encoding=ENC Select the character encoding to use.\n\ 429 -f | --print-file-name Print the file name before each string.\n\ 430 -h | --help Print a help message and exit.\n\ 431 -n N | --bytes=N | -N Print sequences with 'N' or more characters.\n\ 432 -o Print offsets in octal.\n\ 433 -t R | --radix=R Print offsets using the radix named by 'R'.\n\ 434 -v | --version Print a version identifier and exit.\n" 435 436 void 437 usage(void) 438 { 439 (void) fprintf(stderr, USAGE_MESSAGE, ELFTC_GETPROGNAME()); 440 exit(EXIT_FAILURE); 441 } 442 443 void 444 show_version(void) 445 { 446 (void) printf("%s (%s)\n", ELFTC_GETPROGNAME(), elftc_version()); 447 exit(EXIT_SUCCESS); 448 } 449