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 <sys/link.h>
83 #include <elfcap.h>
84 #include "file.h"
85 #include "elf_read.h"
86
87 extern const char *File;
88
89 static int get_class(void);
90 static int get_version(void);
91 static int get_format(void);
92 static int process_shdr(Elf_Info *);
93 static int process_phdr(Elf_Info *);
94 static int file_xlatetom(Elf_Type, char *);
95 static int xlatetom_nhdr(Elf_Nhdr *);
96 static int get_phdr(Elf_Info *, int);
97 static int get_shdr(Elf_Info *, int);
98
99 static Elf_Ehdr EI_Ehdr; /* Elf_Ehdr to be stored */
100 static Elf_Word EI_Ehdr_shnum; /* # section headers */
101 static Elf_Word EI_Ehdr_phnum; /* # program headers */
102 static Elf_Word EI_Ehdr_shstrndx; /* Index of section hdr string table */
103 static Elf_Shdr EI_Shdr; /* recent Elf_Shdr to be stored */
104 static Elf_Phdr EI_Phdr; /* recent Elf_Phdr to be stored */
105
106
107 static int
108 get_class(void)
109 {
110 return (EI_Ehdr.e_ident[EI_CLASS]);
111 }
112
113 static int
114 get_version(void)
115 {
116 /* do as what libelf:_elf_config() does */
117 return (EI_Ehdr.e_ident[EI_VERSION] ?
118 EI_Ehdr.e_ident[EI_VERSION] : 1);
119 }
120
121 static int
122 get_format(void)
123 {
124 return (EI_Ehdr.e_ident[EI_DATA]);
125 }
126
127 /*
128 * file_xlatetom: translate different headers from file
129 * representation to memory representaion.
130 */
131 #define HDRSZ 512
132 static int
133 file_xlatetom(Elf_Type type, char *hdr)
134 {
135 Elf_Data src, dst;
136 char *hbuf[HDRSZ];
137 int version, format;
138
139 version = get_version();
140 format = get_format();
141
142 /* will convert only these types */
143 if (type != ELF_T_EHDR && type != ELF_T_PHDR &&
144 type != ELF_T_SHDR && type != ELF_T_WORD &&
145 type != ELF_T_CAP && type != ELF_T_DYN)
146 return (ELF_READ_FAIL);
147
148 src.d_buf = (Elf_Void *)hdr;
149 src.d_type = type;
150 src.d_version = version;
151
152 dst.d_buf = (Elf_Void *)&hbuf;
153 dst.d_version = EV_CURRENT;
154
155 src.d_size = elf_fsize(type, 1, version);
156 dst.d_size = elf_fsize(type, 1, EV_CURRENT);
157 if (elf_xlatetom(&dst, &src, format) == NULL)
158 return (ELF_READ_FAIL);
159
160 (void) memcpy(hdr, &hbuf, dst.d_size);
161 return (ELF_READ_OKAY);
162 }
163
164 /*
165 * xlatetom_nhdr: There is no routine to convert Note header
166 * so we convert each field of this header.
167 */
168 static int
169 xlatetom_nhdr(Elf_Nhdr *nhdr)
170 {
171 int r = ELF_READ_FAIL;
172
173 r |= file_xlatetom(ELF_T_WORD, (char *)&nhdr->n_namesz);
174 r |= file_xlatetom(ELF_T_WORD, (char *)&nhdr->n_descsz);
175 r |= file_xlatetom(ELF_T_WORD, (char *)&nhdr->n_type);
176 return (r);
177 }
178
179 /*
180 * elf_read: reads elf header, program, section headers to
181 * collect all information needed for file(1)
182 * output and stores them in Elf_Info.
183 */
184 int
185 elf_read(int fd, Elf_Info *EI)
186 {
187 FILE_ELF_SIZE_T size;
188 int ret = 1;
189
190 Elf_Ehdr *ehdr = &EI_Ehdr;
191
192 EI->elffd = fd;
193 size = sizeof (Elf_Ehdr);
194
195 if (pread64(EI->elffd, (void*)ehdr, size, 0) != size)
196 ret = 0;
197
198
199 if (file_xlatetom(ELF_T_EHDR, (char *)ehdr) == ELF_READ_FAIL)
200 ret = 0;
201
202 if (EI->file == NULL)
203 return (ELF_READ_FAIL);
204
205 /*
206 * Extended section or program indexes in use? If so, special
207 * values in the ELF header redirect us to get the real values
208 * from shdr[0].
209 */
210 EI_Ehdr_shnum = EI_Ehdr.e_shnum;
211 EI_Ehdr_phnum = EI_Ehdr.e_phnum;
212 EI_Ehdr_shstrndx = EI_Ehdr.e_shstrndx;
213 if (((EI_Ehdr_shnum == 0) || (EI_Ehdr_phnum == PN_XNUM)) &&
214 (EI_Ehdr.e_shoff != 0)) {
215 if (get_shdr(EI, 0) == ELF_READ_FAIL)
216 return (ELF_READ_FAIL);
217 if (EI_Ehdr_shnum == 0)
218 EI_Ehdr_shnum = EI_Shdr.sh_size;
219 if ((EI_Ehdr_phnum == PN_XNUM) && (EI_Shdr.sh_info != 0))
220 EI_Ehdr_phnum = EI_Shdr.sh_info;
221 if (EI_Ehdr_shstrndx == SHN_XINDEX)
222 EI_Ehdr_shstrndx = EI_Shdr.sh_link;
223 }
224
225 EI->type = ehdr->e_type;
226 EI->machine = ehdr->e_machine;
227 EI->flags = ehdr->e_flags;
228
229 if (ret == 0) {
230 (void) fprintf(stderr, gettext("%s: %s: can't "
231 "read ELF header\n"), File, EI->file);
232 return (ELF_READ_FAIL);
233 }
234 if (process_phdr(EI) == ELF_READ_FAIL)
235 return (ELF_READ_FAIL);
236
237 /* We don't need section info for core files */
238 if (ehdr->e_type != ET_CORE)
239 if (process_shdr(EI) == ELF_READ_FAIL)
240 return (ELF_READ_FAIL);
241
242 return (ELF_READ_OKAY);
243 }
244
245 /*
246 * get_phdr: reads program header of specified index.
247 */
248 static int
249 get_phdr(Elf_Info *EI, int inx)
250 {
251 FILE_ELF_OFF_T off = 0;
252 FILE_ELF_SIZE_T size;
253
254 if (inx >= EI_Ehdr_phnum)
255 return (ELF_READ_FAIL);
256
257 size = sizeof (Elf_Phdr);
258 off = (FILE_ELF_OFF_T)EI_Ehdr.e_phoff + (inx * size);
259 if (pread64(EI->elffd, (void *)&EI_Phdr, size, off) != size)
260 return (ELF_READ_FAIL);
261
262 if (file_xlatetom(ELF_T_PHDR, (char *)&EI_Phdr) == ELF_READ_FAIL)
263 return (ELF_READ_FAIL);
264
265 return (ELF_READ_OKAY);
266 }
267
268 /*
269 * get_shdr: reads section header of specified index.
270 */
271 static int
272 get_shdr(Elf_Info *EI, int inx)
273 {
274 FILE_ELF_OFF_T off = 0;
275 FILE_ELF_SIZE_T size;
276
277 /*
278 * Prevent access to non-existent section headers.
279 *
280 * A value of 0 for e_shoff means that there is no section header
281 * array in the file. A value of 0 for e_shndx does not necessarily
282 * mean this - there can still be a 1-element section header array
283 * to support extended section or program header indexes that
284 * exceed the 16-bit fields used in the ELF header to represent them.
285 */
286 if ((EI_Ehdr.e_shoff == 0) || ((inx > 0) && (inx >= EI_Ehdr_shnum)))
287 return (ELF_READ_FAIL);
288
289 size = sizeof (Elf_Shdr);
290 off = (FILE_ELF_OFF_T)EI_Ehdr.e_shoff + (inx * size);
291
292 if (pread64(EI->elffd, (void *)&EI_Shdr, size, off) != size)
293 return (ELF_READ_FAIL);
294
295 if (file_xlatetom(ELF_T_SHDR, (char *)&EI_Shdr) == ELF_READ_FAIL)
296 return (ELF_READ_FAIL);
297
298 return (ELF_READ_OKAY);
299 }
300
301 /*
302 * process_phdr: Read Program Headers and see if it is a core
303 * file of either new or (pre-restructured /proc)
304 * type, read the name of the file that dumped this
305 * core, else see if this is a dynamically linked.
306 */
307 static int
308 process_phdr(Elf_Info *EI)
309 {
310 register int inx;
311
312 Elf_Nhdr Nhdr, *nhdr; /* note header just read */
313 Elf_Phdr *phdr = &EI_Phdr;
314
315 FILE_ELF_SIZE_T nsz, nmsz, dsz;
316 FILE_ELF_OFF_T offset;
317 int class;
318 int ntype;
319 char *psinfo, *fname;
320
321 nsz = sizeof (Elf_Nhdr);
322 nhdr = &Nhdr;
323 class = get_class();
324 for (inx = 0; inx < EI_Ehdr_phnum; inx++) {
325 if (get_phdr(EI, inx) == ELF_READ_FAIL)
326 return (ELF_READ_FAIL);
327
328 /* read the note if it is a core */
329 if (phdr->p_type == PT_NOTE &&
330 EI_Ehdr.e_type == ET_CORE) {
331 /*
332 * If the next segment is also a note, use it instead.
333 */
334 if (get_phdr(EI, inx+1) == ELF_READ_FAIL)
335 return (ELF_READ_FAIL);
336 if (phdr->p_type != PT_NOTE) {
337 /* read the first phdr back */
338 if (get_phdr(EI, inx) == ELF_READ_FAIL)
339 return (ELF_READ_FAIL);
340 }
341 offset = phdr->p_offset;
342 if (pread64(EI->elffd, (void *)nhdr, nsz, offset)
343 != nsz)
344 return (ELF_READ_FAIL);
345
346 /* Translate the ELF note header */
347 if (xlatetom_nhdr(nhdr) == ELF_READ_FAIL)
348 return (ELF_READ_FAIL);
349
350 ntype = nhdr->n_type;
351 nmsz = nhdr->n_namesz;
352 dsz = nhdr->n_descsz;
353
354 offset += nsz + ((nmsz + 0x03) & ~0x3);
355 if ((psinfo = malloc(dsz)) == NULL) {
356 int err = errno;
357 (void) fprintf(stderr, gettext("%s: malloc "
358 "failed: %s\n"), File, strerror(err));
359 exit(1);
360 }
361 if (pread64(EI->elffd, psinfo, dsz, offset) != dsz)
362 return (ELF_READ_FAIL);
363 /*
364 * We want to print the string contained
365 * in psinfo->pr_fname[], where 'psinfo'
366 * is either an old NT_PRPSINFO structure
367 * or a new NT_PSINFO structure.
368 *
369 * Old core files have only type NT_PRPSINFO.
370 * New core files have type NT_PSINFO.
371 *
372 * These structures are also different by
373 * virtue of being contained in a core file
374 * of either 32-bit or 64-bit type.
375 *
376 * To further complicate matters, we ourself
377 * might be compiled either 32-bit or 64-bit.
378 *
379 * For these reason, we just *know* the offsets of
380 * pr_fname[] into the four different structures
381 * here, regardless of how we are compiled.
382 */
383 if (class == ELFCLASS32) {
384 /* 32-bit core file, 32-bit structures */
385 if (ntype == NT_PSINFO)
386 fname = psinfo + 88;
387 else /* old: NT_PRPSINFO */
388 fname = psinfo + 84;
389 } else if (class == ELFCLASS64) {
390 /* 64-bit core file, 64-bit structures */
391 if (ntype == NT_PSINFO)
392 fname = psinfo + 136;
393 else /* old: NT_PRPSINFO */
394 fname = psinfo + 120;
395 }
396 EI->core_type = (ntype == NT_PRPSINFO)?
397 EC_OLDCORE : EC_NEWCORE;
398 (void) memcpy(EI->fname, fname, strlen(fname));
399 free(psinfo);
400 }
401 if (phdr->p_type == PT_DYNAMIC) {
402 EI->dynamic = B_TRUE;
403 }
404 }
405 return (ELF_READ_OKAY);
406 }
407
408 /*
409 * process_shdr: Read Section Headers to attempt to get HW/SW
410 * capabilities by looking at the SUNW_cap
411 * section and set string in Elf_Info.
412 * Also look for symbol tables and debug
413 * information sections. Set the "stripped" field
414 * in Elf_Info with corresponding flags.
415 */
416 static int
417 process_shdr(Elf_Info *EI)
418 {
419 int mac;
420 int i, idx;
421 char *strtab;
422 size_t strtab_sz;
423 uint64_t j;
424 Elf_Shdr *shdr = &EI_Shdr;
425
426 mac = EI_Ehdr.e_machine;
427
428 /* if there are no sections, return success anyway */
429 if (EI_Ehdr.e_shoff == 0 && EI_Ehdr_shnum == 0)
430 return (ELF_READ_OKAY);
431
432 /* read section names from String Section */
433 if (get_shdr(EI, EI_Ehdr_shstrndx) == ELF_READ_FAIL)
434 return (ELF_READ_FAIL);
435
436 if ((strtab = malloc(shdr->sh_size)) == NULL)
437 return (ELF_READ_FAIL);
438
439 if (pread64(EI->elffd, strtab, shdr->sh_size, shdr->sh_offset)
440 != shdr->sh_size)
441 return (ELF_READ_FAIL);
442
443 strtab_sz = shdr->sh_size;
444
445 /* read all the sections and process them */
446 for (idx = 1, i = 0; i < EI_Ehdr_shnum; idx++, i++) {
447 char *shnam;
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 if (shdr->sh_type == SHT_SUNW_cap) {
458 char capstr[128];
459 Elf_Cap Chdr;
460 FILE_ELF_OFF_T cap_off;
461 FILE_ELF_SIZE_T csize;
462 uint64_t capn;
463
464 cap_off = shdr->sh_offset;
465 csize = sizeof (Elf_Cap);
466
467 if (shdr->sh_size == 0 || shdr->sh_entsize == 0) {
468 (void) fprintf(stderr, ELF_ERR_ELFCAP1,
469 File, EI->file);
470 return (ELF_READ_FAIL);
471 }
472 capn = (shdr->sh_size / shdr->sh_entsize);
473 for (j = 0; j < capn; j++) {
474 /*
475 * read cap and xlate the values
476 */
477 if ((pread64(EI->elffd, &Chdr, csize, cap_off)
478 != csize) ||
479 file_xlatetom(ELF_T_CAP, (char *)&Chdr)
480 == 0) {
481 (void) fprintf(stderr, ELF_ERR_ELFCAP2,
482 File, EI->file);
483 return (ELF_READ_FAIL);
484 }
485
486 cap_off += csize;
487
488 /*
489 * Each capatibility group is terminated with
490 * CA_SUNW_NULL. Groups other than the first
491 * represent symbol capabilities, and aren't
492 * interesting here.
493 */
494 if (Chdr.c_tag == CA_SUNW_NULL)
495 break;
496
497 (void) elfcap_tag_to_str(ELFCAP_STYLE_UC,
498 Chdr.c_tag, Chdr.c_un.c_val, capstr,
499 sizeof (capstr), ELFCAP_FMT_SNGSPACE,
500 mac);
501
502 if ((*EI->cap_str != '\0') && (*capstr != '\0'))
503 (void) strlcat(EI->cap_str, " ",
504 sizeof (EI->cap_str));
505
506 (void) strlcat(EI->cap_str, capstr,
507 sizeof (EI->cap_str));
508 }
509 } else if (shdr->sh_type == SHT_DYNAMIC) {
510 Elf_Dyn dyn;
511 FILE_ELF_SIZE_T dsize;
512 FILE_ELF_OFF_T doff;
513 uint64_t dynn;
514
515 doff = shdr->sh_offset;
516 dsize = sizeof (Elf_Dyn);
517
518 if (shdr->sh_size == 0 || shdr->sh_entsize == 0) {
519 (void) fprintf(stderr, ELF_ERR_DYNAMIC1,
520 File, EI->file);
521 return (ELF_READ_FAIL);
522 }
523
524 dynn = (shdr->sh_size / shdr->sh_entsize);
525 for (j = 0; j < dynn; j++) {
526 if (pread64(EI->elffd, &dyn, dsize, doff)
527 != dsize ||
528 file_xlatetom(ELF_T_DYN, (char *)&dyn)
529 == 0) {
530 (void) fprintf(stderr, ELF_ERR_DYNAMIC2,
531 File, EI->file);
532 return (ELF_READ_FAIL);
533 }
534
535 doff += dsize;
536
537 if ((dyn.d_tag == DT_SUNW_KMOD) &&
538 (dyn.d_un.d_val == 1)) {
539 EI->kmod = B_TRUE;
540 }
541 }
542 }
543
544 /*
545 * Definition time:
546 * - "not stripped" means that an executable file
547 * contains a Symbol Table (.symtab)
548 * - "stripped" means that an executable file
549 * does not contain a Symbol Table.
550 * When strip -l or strip -x is run, it strips the
551 * debugging information (.line section name (strip -l),
552 * .line, .debug*, .stabs*, .dwarf* section names
553 * and SHT_SUNW_DEBUGSTR and SHT_SUNW_DEBUG
554 * section types (strip -x), however the Symbol
555 * Table will still be present.
556 * Therefore, if
557 * - No Symbol Table present, then report
558 * "stripped"
559 * - Symbol Table present with debugging
560 * information (line number or debug section names,
561 * or SHT_SUNW_DEBUGSTR or SHT_SUNW_DEBUG section
562 * types) then report:
563 * "not stripped"
564 * - Symbol Table present with no debugging
565 * information (line number or debug section names,
566 * or SHT_SUNW_DEBUGSTR or SHT_SUNW_DEBUG section
567 * types) then report:
568 * "not stripped, no debugging information
569 * available"
570 */
571 if ((EI->stripped & E_NOSTRIP) == E_NOSTRIP)
572 continue;
573
574 if (!(EI->stripped & E_SYMTAB) &&
575 (shdr->sh_type == SHT_SYMTAB)) {
576 EI->stripped |= E_SYMTAB;
577 continue;
578 }
579
580 if (shdr->sh_name >= strtab_sz)
581 shnam = NULL;
582 else
583 shnam = &strtab[shdr->sh_name];
584
585 if (!(EI->stripped & E_DBGINF) &&
586 ((shdr->sh_type == SHT_SUNW_DEBUG) ||
587 (shdr->sh_type == SHT_SUNW_DEBUGSTR) ||
588 (shnam != NULL && is_in_list(shnam)))) {
589 EI->stripped |= E_DBGINF;
590 }
591 }
592 free(strtab);
593
594 return (ELF_READ_OKAY);
595 }