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comparison usr/src/cmd/file/elf_read.c @ 0:c9caec207d52 b86

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Initial porting based on b86
author Koji Uno <koji.uno@sun.com>
date Tue, 02 Jun 2009 18:56:50 +0900
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children 1a15d5aaf794
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-1:000000000000 0:c9caec207d52
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 #pragma ident "@(#)elf_read.c 1.5 07/11/30 SMI"
34
35 /*
36 * ELF files can exceed 2GB in size. A standard 32-bit program
37 * like 'file' cannot read past 2GB, and will be unable to see
38 * the ELF section headers that typically are at the end of the
39 * object. The simplest solution to this problem would be to make
40 * the 'file' command a 64-bit application. However, as a matter of
41 * policy, we do not want to require this. A simple command like
42 * 'file' should not carry such a requirement, especially as we
43 * support 32-bit only hardware.
44 *
45 * An alternative solution is to build this code as 32-bit
46 * large file aware. The usual way to do this is to define a pair
47 * of preprocessor definitions:
48 *
49 * _LARGEFILE64_SOURCE
50 * Map standard I/O routines to their largefile aware versions.
51 *
52 * _FILE_OFFSET_BITS=64
53 * Map off_t to off64_t
54 *
55 * The problem with this solution is that libelf is not large file capable,
56 * and the libelf header file will prevent compilation if
57 * _FILE_OFFSET_BITS is set to 64.
58 *
59 * So, the solution used in this code is to define _LARGEFILE64_SOURCE
60 * to get access to the 64-bit APIs, not to define _FILE_OFFSET_BITS, and to
61 * use our own types in place of off_t, and size_t. We read all the file
62 * data directly using pread64(), and avoid the use of libelf for anything
63 * other than the xlate functionality.
64 */
65 #define _LARGEFILE64_SOURCE
66 #define FILE_ELF_OFF_T off64_t
67 #define FILE_ELF_SIZE_T uint64_t
68
69 #include <ctype.h>
70 #include <unistd.h>
71 #include <fcntl.h>
72 #include <stdio.h>
73 #include <libelf.h>
74 #include <stdlib.h>
75 #include <limits.h>
76 #include <locale.h>
77 #include <string.h>
78 #include <errno.h>
79 #include <procfs.h>
80 #include <sys/param.h>
81 #include <sys/types.h>
82 #include <sys/stat.h>
83 #include <sys/elf.h>
84 #include <elfcap.h>
85 #include "file.h"
86 #include "elf_read.h"
87
88 extern const char *File;
89
90 static int get_class(void);
91 static int get_version(void);
92 static int get_format(void);
93 static int process_shdr(Elf_Info *);
94 static int process_phdr(Elf_Info *);
95 static int file_xlatetom(Elf_Type, char *);
96 static int xlatetom_nhdr(Elf_Nhdr *);
97 static int get_phdr(Elf_Info *, int);
98 static int get_shdr(Elf_Info *, int);
99
100 static Elf_Ehdr EI_Ehdr; /* Elf_Ehdr to be stored */
101 static Elf_Word EI_Ehdr_shnum; /* # section headers */
102 static Elf_Word EI_Ehdr_phnum; /* # program headers */
103 static Elf_Word EI_Ehdr_shstrndx; /* Index of section hdr string table */
104 static Elf_Shdr EI_Shdr; /* recent Elf_Shdr to be stored */
105 static Elf_Phdr EI_Phdr; /* recent Elf_Phdr to be stored */
106
107
108 static int
109 get_class(void)
110 {
111 return (EI_Ehdr.e_ident[EI_CLASS]);
112 }
113
114 static int
115 get_version(void)
116 {
117 /* do as what libelf:_elf_config() does */
118 return (EI_Ehdr.e_ident[EI_VERSION] ?
119 EI_Ehdr.e_ident[EI_VERSION] : 1);
120 }
121
122 static int
123 get_format(void)
124 {
125 return (EI_Ehdr.e_ident[EI_DATA]);
126 }
127
128 /*
129 * file_xlatetom: translate different headers from file
130 * representation to memory representaion.
131 */
132 #define HDRSZ 512
133 static int
134 file_xlatetom(Elf_Type type, char *hdr)
135 {
136 Elf_Data src, dst;
137 char *hbuf[HDRSZ];
138 int version, format;
139
140 version = get_version();
141 format = get_format();
142
143 /* will convert only these types */
144 if (type != ELF_T_EHDR && type != ELF_T_PHDR &&
145 type != ELF_T_SHDR && type != ELF_T_WORD &&
146 type != ELF_T_CAP)
147 return (ELF_READ_FAIL);
148
149 src.d_buf = (Elf_Void *)hdr;
150 src.d_type = type;
151 src.d_version = version;
152
153 dst.d_buf = (Elf_Void *)&hbuf;
154 dst.d_version = EV_CURRENT;
155
156 src.d_size = elf_fsize(type, 1, version);
157 dst.d_size = elf_fsize(type, 1, EV_CURRENT);
158 if (elf_xlatetom(&dst, &src, format) == NULL)
159 return (ELF_READ_FAIL);
160
161 (void) memcpy(hdr, &hbuf, dst.d_size);
162 return (ELF_READ_OKAY);
163 }
164
165 /*
166 * xlatetom_nhdr: There is no routine to convert Note header
167 * so we convert each field of this header.
168 */
169 static int
170 xlatetom_nhdr(Elf_Nhdr *nhdr)
171 {
172 int r = ELF_READ_FAIL;
173
174 r |= file_xlatetom(ELF_T_WORD, (char *)&nhdr->n_namesz);
175 r |= file_xlatetom(ELF_T_WORD, (char *)&nhdr->n_descsz);
176 r |= file_xlatetom(ELF_T_WORD, (char *)&nhdr->n_type);
177 return (r);
178 }
179
180 /*
181 * elf_read: reads elf header, program, section headers to
182 * collect all information needed for file(1)
183 * output and stores them in Elf_Info.
184 */
185 int
186 elf_read(int fd, Elf_Info *EI)
187 {
188 FILE_ELF_SIZE_T size;
189 int ret = 1;
190
191 Elf_Ehdr *ehdr = &EI_Ehdr;
192
193 EI->elffd = fd;
194 size = sizeof (Elf_Ehdr);
195
196 if (pread64(EI->elffd, (void*)ehdr, size, 0) != size)
197 ret = 0;
198
199
200 if (file_xlatetom(ELF_T_EHDR, (char *)ehdr) == ELF_READ_FAIL)
201 ret = 0;
202
203 if (EI->file == NULL)
204 return (ELF_READ_FAIL);
205
206 /*
207 * Extended section or program indexes in use? If so, special
208 * values in the ELF header redirect us to get the real values
209 * from shdr[0].
210 */
211 EI_Ehdr_shnum = EI_Ehdr.e_shnum;
212 EI_Ehdr_phnum = EI_Ehdr.e_phnum;
213 EI_Ehdr_shstrndx = EI_Ehdr.e_shstrndx;
214 if (((EI_Ehdr_shnum == 0) || (EI_Ehdr_phnum == PN_XNUM)) &&
215 (EI_Ehdr.e_shoff != 0)) {
216 if (get_shdr(EI, 0) == ELF_READ_FAIL)
217 return (ELF_READ_FAIL);
218 if (EI_Ehdr_shnum == 0)
219 EI_Ehdr_shnum = EI_Shdr.sh_size;
220 if ((EI_Ehdr_phnum == PN_XNUM) && (EI_Shdr.sh_info != 0))
221 EI_Ehdr_phnum = EI_Shdr.sh_info;
222 if (EI_Ehdr_shstrndx == SHN_XINDEX)
223 EI_Ehdr_shstrndx = EI_Shdr.sh_link;
224 }
225
226 EI->type = ehdr->e_type;
227 EI->machine = ehdr->e_machine;
228 EI->flags = ehdr->e_flags;
229
230 if (ret == 0) {
231 (void) fprintf(stderr, gettext("%s: %s: can't "
232 "read ELF header\n"), File, EI->file);
233 return (ELF_READ_FAIL);
234 }
235 if (process_phdr(EI) == ELF_READ_FAIL)
236 return (ELF_READ_FAIL);
237
238 /* We don't need section info for core files */
239 if (ehdr->e_type != ET_CORE)
240 if (process_shdr(EI) == ELF_READ_FAIL)
241 return (ELF_READ_FAIL);
242
243 return (ELF_READ_OKAY);
244 }
245
246 /*
247 * get_phdr: reads program header of specified index.
248 */
249 static int
250 get_phdr(Elf_Info *EI, int inx)
251 {
252 FILE_ELF_OFF_T off = 0;
253 FILE_ELF_SIZE_T size;
254
255 if (inx >= EI_Ehdr_phnum)
256 return (ELF_READ_FAIL);
257
258 size = sizeof (Elf_Phdr);
259 off = (FILE_ELF_OFF_T)EI_Ehdr.e_phoff + (inx * size);
260 if (pread64(EI->elffd, (void *)&EI_Phdr, size, off) != size)
261 return (ELF_READ_FAIL);
262
263 if (file_xlatetom(ELF_T_PHDR, (char *)&EI_Phdr) == ELF_READ_FAIL)
264 return (ELF_READ_FAIL);
265
266 return (ELF_READ_OKAY);
267 }
268
269 /*
270 * get_shdr: reads section header of specified index.
271 */
272 static int
273 get_shdr(Elf_Info *EI, int inx)
274 {
275 FILE_ELF_OFF_T off = 0;
276 FILE_ELF_SIZE_T size;
277
278 /*
279 * Prevent access to non-existent section headers.
280 *
281 * A value of 0 for e_shoff means that there is no section header
282 * array in the file. A value of 0 for e_shndx does not necessarily
283 * mean this - there can still be a 1-element section header array
284 * to support extended section or program header indexes that
285 * exceed the 16-bit fields used in the ELF header to represent them.
286 */
287 if ((EI_Ehdr.e_shoff == 0) || ((inx > 0) && (inx >= EI_Ehdr_shnum)))
288 return (ELF_READ_FAIL);
289
290 size = sizeof (Elf_Shdr);
291 off = (FILE_ELF_OFF_T)EI_Ehdr.e_shoff + (inx * size);
292
293 if (pread64(EI->elffd, (void *)&EI_Shdr, size, off) != size)
294 return (ELF_READ_FAIL);
295
296 if (file_xlatetom(ELF_T_SHDR, (char *)&EI_Shdr) == ELF_READ_FAIL)
297 return (ELF_READ_FAIL);
298
299 return (ELF_READ_OKAY);
300 }
301
302 /*
303 * process_phdr: Read Program Headers and see if it is a core
304 * file of either new or (pre-restructured /proc)
305 * type, read the name of the file that dumped this
306 * core, else see if this is a dynamically linked.
307 */
308 static int
309 process_phdr(Elf_Info *EI)
310 {
311 register int inx;
312
313 Elf_Nhdr Nhdr, *nhdr; /* note header just read */
314 Elf_Phdr *phdr = &EI_Phdr;
315
316 FILE_ELF_SIZE_T nsz, nmsz, dsz;
317 FILE_ELF_OFF_T offset;
318 int class;
319 int ntype;
320 char *psinfo, *fname;
321
322 nsz = sizeof (Elf_Nhdr);
323 nhdr = &Nhdr;
324 class = get_class();
325 for (inx = 0; inx < EI_Ehdr_phnum; inx++) {
326 if (get_phdr(EI, inx) == ELF_READ_FAIL)
327 return (ELF_READ_FAIL);
328
329 /* read the note if it is a core */
330 if (phdr->p_type == PT_NOTE &&
331 EI_Ehdr.e_type == ET_CORE) {
332 /*
333 * If the next segment is also a note, use it instead.
334 */
335 if (get_phdr(EI, inx+1) == ELF_READ_FAIL)
336 return (ELF_READ_FAIL);
337 if (phdr->p_type != PT_NOTE) {
338 /* read the first phdr back */
339 if (get_phdr(EI, inx) == ELF_READ_FAIL)
340 return (ELF_READ_FAIL);
341 }
342 offset = phdr->p_offset;
343 if (pread64(EI->elffd, (void *)nhdr, nsz, offset)
344 != nsz)
345 return (ELF_READ_FAIL);
346
347 /* Translate the ELF note header */
348 if (xlatetom_nhdr(nhdr) == ELF_READ_FAIL)
349 return (ELF_READ_FAIL);
350
351 ntype = nhdr->n_type;
352 nmsz = nhdr->n_namesz;
353 dsz = nhdr->n_descsz;
354
355 offset += nsz + ((nmsz + 0x03) & ~0x3);
356 if ((psinfo = malloc(dsz)) == NULL) {
357 int err = errno;
358 (void) fprintf(stderr, gettext("%s: malloc "
359 "failed: %s\n"), File, strerror(err));
360 exit(1);
361 }
362 if (pread64(EI->elffd, psinfo, dsz, offset) != dsz)
363 return (ELF_READ_FAIL);
364 /*
365 * We want to print the string contained
366 * in psinfo->pr_fname[], where 'psinfo'
367 * is either an old NT_PRPSINFO structure
368 * or a new NT_PSINFO structure.
369 *
370 * Old core files have only type NT_PRPSINFO.
371 * New core files have type NT_PSINFO.
372 *
373 * These structures are also different by
374 * virtue of being contained in a core file
375 * of either 32-bit or 64-bit type.
376 *
377 * To further complicate matters, we ourself
378 * might be compiled either 32-bit or 64-bit.
379 *
380 * For these reason, we just *know* the offsets of
381 * pr_fname[] into the four different structures
382 * here, regardless of how we are compiled.
383 */
384 if (class == ELFCLASS32) {
385 /* 32-bit core file, 32-bit structures */
386 if (ntype == NT_PSINFO)
387 fname = psinfo + 88;
388 else /* old: NT_PRPSINFO */
389 fname = psinfo + 84;
390 } else if (class == ELFCLASS64) {
391 /* 64-bit core file, 64-bit structures */
392 if (ntype == NT_PSINFO)
393 fname = psinfo + 136;
394 else /* old: NT_PRPSINFO */
395 fname = psinfo + 120;
396 }
397 EI->core_type = (ntype == NT_PRPSINFO)?
398 EC_OLDCORE : EC_NEWCORE;
399 (void) memcpy(EI->fname, fname, strlen(fname));
400 free(psinfo);
401 }
402 if (phdr->p_type == PT_DYNAMIC) {
403 EI->dynamic = B_TRUE;
404 }
405 }
406 return (ELF_READ_OKAY);
407 }
408
409 /*
410 * process_shdr: Read Section Headers to attempt to get HW/SW
411 * capabilities by looking at the SUNW_cap
412 * section and set string in Elf_Info.
413 * Also look for symbol tables and debug
414 * information sections. Set the "stripped" field
415 * in Elf_Info with corresponding flags.
416 */
417 static int
418 process_shdr(Elf_Info *EI)
419 {
420 int capn, mac;
421 int i, j, idx;
422 FILE_ELF_OFF_T cap_off;
423 FILE_ELF_SIZE_T csize;
424 char *section_name;
425 Elf_Cap Chdr;
426 Elf_Shdr *shdr = &EI_Shdr;
427
428
429 csize = sizeof (Elf_Cap);
430 mac = EI_Ehdr.e_machine;
431
432 /* if there are no sections, return success anyway */
433 if (EI_Ehdr.e_shoff == 0 && EI_Ehdr_shnum == 0)
434 return (ELF_READ_OKAY);
435
436 /* read section names from String Section */
437 if (get_shdr(EI, EI_Ehdr_shstrndx) == ELF_READ_FAIL)
438 return (ELF_READ_FAIL);
439
440 if ((section_name = malloc(shdr->sh_size)) == NULL)
441 return (ELF_READ_FAIL);
442
443 if (pread64(EI->elffd, section_name, shdr->sh_size, shdr->sh_offset)
444 != shdr->sh_size)
445 return (ELF_READ_FAIL);
446
447 /* read all the sections and process them */
448 for (idx = 1, i = 0; i < EI_Ehdr_shnum; idx++, i++) {
449 char *str;
450
451 if (get_shdr(EI, i) == ELF_READ_FAIL)
452 return (ELF_READ_FAIL);
453
454 if (shdr->sh_type == SHT_NULL) {
455 idx--;
456 continue;
457 }
458
459 cap_off = shdr->sh_offset;
460 if (shdr->sh_type == SHT_SUNW_cap) {
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 if (Chdr.c_tag != CA_SUNW_NULL) {
481 (void) elfcap_tag_to_str(
482 ELFCAP_STYLE_UC, Chdr.c_tag,
483 Chdr.c_un.c_val, EI->cap_str,
484 sizeof (EI->cap_str),
485 ELFCAP_FMT_SNGSPACE, mac);
486 }
487 cap_off += csize;
488 }
489 }
490
491 /*
492 * Definition time:
493 * - "not stripped" means that an executable file
494 * contains a Symbol Table (.symtab)
495 * - "stripped" means that an executable file
496 * does not contain a Symbol Table.
497 * When strip -l or strip -x is run, it strips the
498 * debugging information (.line section name (strip -l),
499 * .line, .debug*, .stabs*, .dwarf* section names
500 * and SHT_SUNW_DEBUGSTR and SHT_SUNW_DEBUG
501 * section types (strip -x), however the Symbol
502 * Table will still be present.
503 * Therefore, if
504 * - No Symbol Table present, then report
505 * "stripped"
506 * - Symbol Table present with debugging
507 * information (line number or debug section names,
508 * or SHT_SUNW_DEBUGSTR or SHT_SUNW_DEBUG section
509 * types) then report:
510 * "not stripped"
511 * - Symbol Table present with no debugging
512 * information (line number or debug section names,
513 * or SHT_SUNW_DEBUGSTR or SHT_SUNW_DEBUG section
514 * types) then report:
515 * "not stripped, no debugging information
516 * available"
517 */
518 if ((EI->stripped & E_NOSTRIP) == E_NOSTRIP)
519 continue;
520
521 if (!(EI->stripped & E_SYMTAB) &&
522 (shdr->sh_type == SHT_SYMTAB)) {
523 EI->stripped |= E_SYMTAB;
524 continue;
525 }
526
527 str = &section_name[shdr->sh_name];
528
529 if (!(EI->stripped & E_DBGINF) &&
530 ((shdr->sh_type == SHT_SUNW_DEBUG) ||
531 (shdr->sh_type == SHT_SUNW_DEBUGSTR) ||
532 (is_in_list(str)))) {
533 EI->stripped |= E_DBGINF;
534 }
535 }
536 free(section_name);
537
538 return (ELF_READ_OKAY);
539 }