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 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
22 /* All Rights Reserved */
23
24
25 /* Copyright (c) 1987, 1988 Microsoft Corporation */
26 /* All Rights Reserved */
27
28 /*
29 * Copyright 2007 Sun Microsystems, Inc. All rights reserved.
30 * Use is subject to license terms.
31 */
32
33 /*
34 * ELF files can exceed 2GB in size. A standard 32-bit program
35 * like 'file' cannot read past 2GB, and will be unable to see
36 * the ELF section headers that typically are at the end of the
37 * object. The simplest solution to this problem would be to make
38 * the 'file' command a 64-bit application. However, as a matter of
39 * policy, we do not want to require this. A simple command like
40 * 'file' should not carry such a requirement, especially as we
41 * support 32-bit only hardware.
42 *
43 * An alternative solution is to build this code as 32-bit
44 * large file aware. The usual way to do this is to define a pair
45 * of preprocessor definitions:
46 *
47 * _LARGEFILE64_SOURCE
48 * Map standard I/O routines to their largefile aware versions.
49 *
50 * _FILE_OFFSET_BITS=64
51 * Map off_t to off64_t
52 *
53 * The problem with this solution is that libelf is not large file capable,
54 * and the libelf header file will prevent compilation if
55 * _FILE_OFFSET_BITS is set to 64.
56 *
57 * So, the solution used in this code is to define _LARGEFILE64_SOURCE
58 * to get access to the 64-bit APIs, not to define _FILE_OFFSET_BITS, and to
59 * use our own types in place of off_t, and size_t. We read all the file
60 * data directly using pread64(), and avoid the use of libelf for anything
61 * other than the xlate functionality.
62 */
63 #define _LARGEFILE64_SOURCE
64 #define FILE_ELF_OFF_T off64_t
65 #define FILE_ELF_SIZE_T uint64_t
66
67 #include <ctype.h>
68 #include <unistd.h>
69 #include <fcntl.h>
70 #include <stdio.h>
71 #include <libelf.h>
72 #include <stdlib.h>
73 #include <limits.h>
74 #include <locale.h>
75 #include <string.h>
76 #include <errno.h>
77 #include <procfs.h>
78 #include <sys/param.h>
79 #include <sys/types.h>
80 #include <sys/stat.h>
81 #include <sys/elf.h>
82 #include <elfcap.h>
83 #include "file.h"
84 #include "elf_read.h"
85
86 extern const char *File;
87
88 static int get_class(void);
89 static int get_version(void);
90 static int get_format(void);
91 static int process_shdr(Elf_Info *);
92 static int process_phdr(Elf_Info *);
93 static int file_xlatetom(Elf_Type, char *);
94 static int xlatetom_nhdr(Elf_Nhdr *);
95 static int get_phdr(Elf_Info *, int);
96 static int get_shdr(Elf_Info *, int);
97
98 static Elf_Ehdr EI_Ehdr; /* Elf_Ehdr to be stored */
99 static Elf_Word EI_Ehdr_shnum; /* # section headers */
100 static Elf_Word EI_Ehdr_phnum; /* # program headers */
101 static Elf_Word EI_Ehdr_shstrndx; /* Index of section hdr string table */
102 static Elf_Shdr EI_Shdr; /* recent Elf_Shdr to be stored */
103 static Elf_Phdr EI_Phdr; /* recent Elf_Phdr to be stored */
104
105
106 static int
107 get_class(void)
108 {
109 return (EI_Ehdr.e_ident[EI_CLASS]);
110 }
111
112 static int
113 get_version(void)
114 {
115 /* do as what libelf:_elf_config() does */
116 return (EI_Ehdr.e_ident[EI_VERSION] ?
117 EI_Ehdr.e_ident[EI_VERSION] : 1);
118 }
119
120 static int
121 get_format(void)
122 {
123 return (EI_Ehdr.e_ident[EI_DATA]);
124 }
125
126 /*
127 * file_xlatetom: translate different headers from file
128 * representation to memory representaion.
129 */
130 #define HDRSZ 512
131 static int
132 file_xlatetom(Elf_Type type, char *hdr)
133 {
134 Elf_Data src, dst;
135 char *hbuf[HDRSZ];
136 int version, format;
137
138 version = get_version();
139 format = get_format();
140
141 /* will convert only these types */
142 if (type != ELF_T_EHDR && type != ELF_T_PHDR &&
143 type != ELF_T_SHDR && type != ELF_T_WORD &&
144 type != ELF_T_CAP)
145 return (ELF_READ_FAIL);
146
147 src.d_buf = (Elf_Void *)hdr;
148 src.d_type = type;
149 src.d_version = version;
150
151 dst.d_buf = (Elf_Void *)&hbuf;
152 dst.d_version = EV_CURRENT;
153
154 src.d_size = elf_fsize(type, 1, version);
155 dst.d_size = elf_fsize(type, 1, EV_CURRENT);
156 if (elf_xlatetom(&dst, &src, format) == NULL)
157 return (ELF_READ_FAIL);
158
159 (void) memcpy(hdr, &hbuf, dst.d_size);
160 return (ELF_READ_OKAY);
161 }
162
163 /*
164 * xlatetom_nhdr: There is no routine to convert Note header
165 * so we convert each field of this header.
166 */
167 static int
168 xlatetom_nhdr(Elf_Nhdr *nhdr)
169 {
170 int r = ELF_READ_FAIL;
171
172 r |= file_xlatetom(ELF_T_WORD, (char *)&nhdr->n_namesz);
173 r |= file_xlatetom(ELF_T_WORD, (char *)&nhdr->n_descsz);
174 r |= file_xlatetom(ELF_T_WORD, (char *)&nhdr->n_type);
175 return (r);
176 }
177
178 /*
179 * elf_read: reads elf header, program, section headers to
180 * collect all information needed for file(1)
181 * output and stores them in Elf_Info.
182 */
183 int
184 elf_read(int fd, Elf_Info *EI)
185 {
186 FILE_ELF_SIZE_T size;
187 int ret = 1;
188
189 Elf_Ehdr *ehdr = &EI_Ehdr;
190
191 EI->elffd = fd;
192 size = sizeof (Elf_Ehdr);
193
194 if (pread64(EI->elffd, (void*)ehdr, size, 0) != size)
195 ret = 0;
196
197
198 if (file_xlatetom(ELF_T_EHDR, (char *)ehdr) == ELF_READ_FAIL)
199 ret = 0;
200
201 if (EI->file == NULL)
202 return (ELF_READ_FAIL);
203
204 /*
205 * Extended section or program indexes in use? If so, special
206 * values in the ELF header redirect us to get the real values
207 * from shdr[0].
208 */
209 EI_Ehdr_shnum = EI_Ehdr.e_shnum;
210 EI_Ehdr_phnum = EI_Ehdr.e_phnum;
211 EI_Ehdr_shstrndx = EI_Ehdr.e_shstrndx;
212 if (((EI_Ehdr_shnum == 0) || (EI_Ehdr_phnum == PN_XNUM)) &&
213 (EI_Ehdr.e_shoff != 0)) {
214 if (get_shdr(EI, 0) == ELF_READ_FAIL)
215 return (ELF_READ_FAIL);
216 if (EI_Ehdr_shnum == 0)
217 EI_Ehdr_shnum = EI_Shdr.sh_size;
218 if ((EI_Ehdr_phnum == PN_XNUM) && (EI_Shdr.sh_info != 0))
219 EI_Ehdr_phnum = EI_Shdr.sh_info;
220 if (EI_Ehdr_shstrndx == SHN_XINDEX)
221 EI_Ehdr_shstrndx = EI_Shdr.sh_link;
222 }
223
224 EI->type = ehdr->e_type;
225 EI->machine = ehdr->e_machine;
226 EI->flags = ehdr->e_flags;
227
228 if (ret == 0) {
229 (void) fprintf(stderr, gettext("%s: %s: can't "
230 "read ELF header\n"), File, EI->file);
231 return (ELF_READ_FAIL);
232 }
233 if (process_phdr(EI) == ELF_READ_FAIL)
234 return (ELF_READ_FAIL);
235
236 /* We don't need section info for core files */
237 if (ehdr->e_type != ET_CORE)
238 if (process_shdr(EI) == ELF_READ_FAIL)
239 return (ELF_READ_FAIL);
240
241 return (ELF_READ_OKAY);
242 }
243
244 /*
245 * get_phdr: reads program header of specified index.
246 */
247 static int
248 get_phdr(Elf_Info *EI, int inx)
249 {
250 FILE_ELF_OFF_T off = 0;
251 FILE_ELF_SIZE_T size;
252
253 if (inx >= EI_Ehdr_phnum)
254 return (ELF_READ_FAIL);
255
256 size = sizeof (Elf_Phdr);
257 off = (FILE_ELF_OFF_T)EI_Ehdr.e_phoff + (inx * size);
258 if (pread64(EI->elffd, (void *)&EI_Phdr, size, off) != size)
259 return (ELF_READ_FAIL);
260
261 if (file_xlatetom(ELF_T_PHDR, (char *)&EI_Phdr) == ELF_READ_FAIL)
262 return (ELF_READ_FAIL);
263
264 return (ELF_READ_OKAY);
265 }
266
267 /*
268 * get_shdr: reads section header of specified index.
269 */
270 static int
271 get_shdr(Elf_Info *EI, int inx)
272 {
273 FILE_ELF_OFF_T off = 0;
274 FILE_ELF_SIZE_T size;
275
276 /*
277 * Prevent access to non-existent section headers.
278 *
279 * A value of 0 for e_shoff means that there is no section header
280 * array in the file. A value of 0 for e_shndx does not necessarily
281 * mean this - there can still be a 1-element section header array
282 * to support extended section or program header indexes that
283 * exceed the 16-bit fields used in the ELF header to represent them.
284 */
285 if ((EI_Ehdr.e_shoff == 0) || ((inx > 0) && (inx >= EI_Ehdr_shnum)))
286 return (ELF_READ_FAIL);
287
288 size = sizeof (Elf_Shdr);
289 off = (FILE_ELF_OFF_T)EI_Ehdr.e_shoff + (inx * size);
290
291 if (pread64(EI->elffd, (void *)&EI_Shdr, size, off) != size)
292 return (ELF_READ_FAIL);
293
294 if (file_xlatetom(ELF_T_SHDR, (char *)&EI_Shdr) == ELF_READ_FAIL)
295 return (ELF_READ_FAIL);
296
297 return (ELF_READ_OKAY);
298 }
299
300 /*
301 * process_phdr: Read Program Headers and see if it is a core
302 * file of either new or (pre-restructured /proc)
303 * type, read the name of the file that dumped this
304 * core, else see if this is a dynamically linked.
305 */
306 static int
307 process_phdr(Elf_Info *EI)
308 {
309 register int inx;
310
311 Elf_Nhdr Nhdr, *nhdr; /* note header just read */
312 Elf_Phdr *phdr = &EI_Phdr;
313
314 FILE_ELF_SIZE_T nsz, nmsz, dsz;
315 FILE_ELF_OFF_T offset;
316 int class;
317 int ntype;
318 char *psinfo, *fname;
319
320 nsz = sizeof (Elf_Nhdr);
321 nhdr = &Nhdr;
322 class = get_class();
323 for (inx = 0; inx < EI_Ehdr_phnum; inx++) {
324 if (get_phdr(EI, inx) == ELF_READ_FAIL)
325 return (ELF_READ_FAIL);
326
327 /* read the note if it is a core */
328 if (phdr->p_type == PT_NOTE &&
329 EI_Ehdr.e_type == ET_CORE) {
330 /*
331 * If the next segment is also a note, use it instead.
332 */
333 if (get_phdr(EI, inx+1) == ELF_READ_FAIL)
334 return (ELF_READ_FAIL);
335 if (phdr->p_type != PT_NOTE) {
336 /* read the first phdr back */
337 if (get_phdr(EI, inx) == ELF_READ_FAIL)
338 return (ELF_READ_FAIL);
339 }
340 offset = phdr->p_offset;
341 if (pread64(EI->elffd, (void *)nhdr, nsz, offset)
342 != nsz)
343 return (ELF_READ_FAIL);
344
345 /* Translate the ELF note header */
346 if (xlatetom_nhdr(nhdr) == ELF_READ_FAIL)
347 return (ELF_READ_FAIL);
348
349 ntype = nhdr->n_type;
350 nmsz = nhdr->n_namesz;
351 dsz = nhdr->n_descsz;
352
353 offset += nsz + ((nmsz + 0x03) & ~0x3);
354 if ((psinfo = malloc(dsz)) == NULL) {
355 int err = errno;
356 (void) fprintf(stderr, gettext("%s: malloc "
357 "failed: %s\n"), File, strerror(err));
358 exit(1);
359 }
360 if (pread64(EI->elffd, psinfo, dsz, offset) != dsz)
361 return (ELF_READ_FAIL);
362 /*
363 * We want to print the string contained
364 * in psinfo->pr_fname[], where 'psinfo'
365 * is either an old NT_PRPSINFO structure
366 * or a new NT_PSINFO structure.
367 *
368 * Old core files have only type NT_PRPSINFO.
369 * New core files have type NT_PSINFO.
370 *
371 * These structures are also different by
372 * virtue of being contained in a core file
373 * of either 32-bit or 64-bit type.
374 *
375 * To further complicate matters, we ourself
376 * might be compiled either 32-bit or 64-bit.
377 *
378 * For these reason, we just *know* the offsets of
379 * pr_fname[] into the four different structures
380 * here, regardless of how we are compiled.
381 */
382 if (class == ELFCLASS32) {
383 /* 32-bit core file, 32-bit structures */
384 if (ntype == NT_PSINFO)
385 fname = psinfo + 88;
386 else /* old: NT_PRPSINFO */
387 fname = psinfo + 84;
388 } else if (class == ELFCLASS64) {
389 /* 64-bit core file, 64-bit structures */
390 if (ntype == NT_PSINFO)
391 fname = psinfo + 136;
392 else /* old: NT_PRPSINFO */
393 fname = psinfo + 120;
394 }
395 EI->core_type = (ntype == NT_PRPSINFO)?
396 EC_OLDCORE : EC_NEWCORE;
397 (void) memcpy(EI->fname, fname, strlen(fname));
398 free(psinfo);
399 }
400 if (phdr->p_type == PT_DYNAMIC) {
401 EI->dynamic = B_TRUE;
402 }
403 }
404 return (ELF_READ_OKAY);
405 }
406
407 /*
408 * process_shdr: Read Section Headers to attempt to get HW/SW
409 * capabilities by looking at the SUNW_cap
410 * section and set string in Elf_Info.
411 * Also look for symbol tables and debug
412 * information sections. Set the "stripped" field
413 * in Elf_Info with corresponding flags.
414 */
415 static int
416 process_shdr(Elf_Info *EI)
417 {
418 int capn, mac;
419 int i, j, idx;
420 FILE_ELF_OFF_T cap_off;
421 FILE_ELF_SIZE_T csize;
422 char *section_name;
423 Elf_Cap Chdr;
424 Elf_Shdr *shdr = &EI_Shdr;
425
426
427 csize = sizeof (Elf_Cap);
428 mac = EI_Ehdr.e_machine;
429
430 /* if there are no sections, return success anyway */
431 if (EI_Ehdr.e_shoff == 0 && EI_Ehdr_shnum == 0)
432 return (ELF_READ_OKAY);
433
434 /* read section names from String Section */
435 if (get_shdr(EI, EI_Ehdr_shstrndx) == ELF_READ_FAIL)
436 return (ELF_READ_FAIL);
437
438 if ((section_name = malloc(shdr->sh_size)) == NULL)
439 return (ELF_READ_FAIL);
440
441 if (pread64(EI->elffd, section_name, shdr->sh_size, shdr->sh_offset)
442 != shdr->sh_size)
443 return (ELF_READ_FAIL);
444
445 /* read all the sections and process them */
446 for (idx = 1, i = 0; i < EI_Ehdr_shnum; idx++, i++) {
447 char *str;
448
449 if (get_shdr(EI, i) == ELF_READ_FAIL)
450 return (ELF_READ_FAIL);
451
452 if (shdr->sh_type == SHT_NULL) {
453 idx--;
454 continue;
455 }
456
457 cap_off = shdr->sh_offset;
458 if (shdr->sh_type == SHT_SUNW_cap) {
459 char capstr[128];
460
461 if (shdr->sh_size == 0 || shdr->sh_entsize == 0) {
462 (void) fprintf(stderr, ELF_ERR_ELFCAP1,
463 File, EI->file);
464 return (ELF_READ_FAIL);
465 }
466 capn = (shdr->sh_size / shdr->sh_entsize);
467 for (j = 0; j < capn; j++) {
468 /*
469 * read cap and xlate the values
470 */
471 if (pread64(EI->elffd, &Chdr, csize, cap_off)
472 != csize ||
473 file_xlatetom(ELF_T_CAP, (char *)&Chdr)
474 == 0) {
475 (void) fprintf(stderr, ELF_ERR_ELFCAP2,
476 File, EI->file);
477 return (ELF_READ_FAIL);
478 }
479
480 cap_off += csize;
481
482 /*
483 * Each capatibility group is terminated with
484 * CA_SUNW_NULL. Groups other than the first
485 * represent symbol capabilities, and aren't
486 * interesting here.
487 */
488 if (Chdr.c_tag == CA_SUNW_NULL)
489 break;
490
491 (void) elfcap_tag_to_str(ELFCAP_STYLE_UC,
492 Chdr.c_tag, Chdr.c_un.c_val, capstr,
493 sizeof (capstr), ELFCAP_FMT_SNGSPACE,
494 mac);
495
496 if ((*EI->cap_str != '\0') && (*capstr != '\0'))
497 (void) strlcat(EI->cap_str, " ",
498 sizeof (EI->cap_str));
499
500 (void) strlcat(EI->cap_str, capstr,
501 sizeof (EI->cap_str));
502 }
503 }
504
505 /*
506 * Definition time:
507 * - "not stripped" means that an executable file
508 * contains a Symbol Table (.symtab)
509 * - "stripped" means that an executable file
510 * does not contain a Symbol Table.
511 * When strip -l or strip -x is run, it strips the
512 * debugging information (.line section name (strip -l),
513 * .line, .debug*, .stabs*, .dwarf* section names
514 * and SHT_SUNW_DEBUGSTR and SHT_SUNW_DEBUG
515 * section types (strip -x), however the Symbol
516 * Table will still be present.
517 * Therefore, if
518 * - No Symbol Table present, then report
519 * "stripped"
520 * - Symbol Table present with debugging
521 * information (line number or debug section names,
522 * or SHT_SUNW_DEBUGSTR or SHT_SUNW_DEBUG section
523 * types) then report:
524 * "not stripped"
525 * - Symbol Table present with no debugging
526 * information (line number or debug section names,
527 * or SHT_SUNW_DEBUGSTR or SHT_SUNW_DEBUG section
528 * types) then report:
529 * "not stripped, no debugging information
530 * available"
531 */
532 if ((EI->stripped & E_NOSTRIP) == E_NOSTRIP)
533 continue;
534
535 if (!(EI->stripped & E_SYMTAB) &&
536 (shdr->sh_type == SHT_SYMTAB)) {
537 EI->stripped |= E_SYMTAB;
538 continue;
539 }
540
541 str = §ion_name[shdr->sh_name];
542
543 if (!(EI->stripped & E_DBGINF) &&
544 ((shdr->sh_type == SHT_SUNW_DEBUG) ||
545 (shdr->sh_type == SHT_SUNW_DEBUGSTR) ||
546 (is_in_list(str)))) {
547 EI->stripped |= E_DBGINF;
548 }
549 }
550 free(section_name);
551
552 return (ELF_READ_OKAY);
553 }