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comparison dynodump/dynodump.c @ 428:3ecd8885ac67 r21-2-22

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date Mon, 13 Aug 2007 11:28:15 +0200
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1 /*
2 * Copyright (c) 1995 by Sun Microsystems, Inc.
3 * All rights reserved.
4 *
5 * This source code is a product of Sun Microsystems, Inc. and is provided
6 * for unrestricted use provided that this legend is included on all tape
7 * media and as a part of the software program in whole or part. Users
8 * may copy or modify this source code without charge, but are not authorized
9 * to license or distribute it to anyone else except as part of a product or
10 * program developed by the user.
11 *
12 * THIS PROGRAM CONTAINS SOURCE CODE COPYRIGHTED BY SUN MICROSYSTEMS, INC.
13 * SUN MICROSYSTEMS, INC., MAKES NO REPRESENTATIONS ABOUT THE SUITABLITY
14 * OF SUCH SOURCE CODE FOR ANY PURPOSE. IT IS PROVIDED "AS IS" WITHOUT
15 * EXPRESS OR IMPLIED WARRANTY OF ANY KIND. SUN MICROSYSTEMS, INC. DISCLAIMS
16 * ALL WARRANTIES WITH REGARD TO SUCH SOURCE CODE, INCLUDING ALL IMPLIED
17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN
18 * NO EVENT SHALL SUN MICROSYSTEMS, INC. BE LIABLE FOR ANY SPECIAL, INDIRECT,
19 * INCIDENTAL, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
20 * FROM USE OF SUCH SOURCE CODE, REGARDLESS OF THE THEORY OF LIABILITY.
21 *
22 * This source code is provided with no support and without any obligation on
23 * the part of Sun Microsystems, Inc. to assist in its use, correction,
24 * modification or enhancement.
25 *
26 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
27 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS
28 * SOURCE CODE OR ANY PART THEREOF.
29 *
30 * Sun Microsystems, Inc.
31 * 2550 Garcia Avenue
32 * Mountain View, California 94043
33 */
34
35 /*
36 * dynodump(3x) dumps a running executable into a specified ELF file. The new
37 * file consists of the memory contents of the original file together with any
38 * heap. This heap is assigned to a new `.heap' section within the new file.
39 *
40 * The new file may be re-executed, and will contain any data modifications
41 * made to the original image up until the time dynodump(3x) was called.
42 *
43 * The original image may have undergone relocations (performed by ld.so.1)
44 * prior to control being transferred to the image. These relocations will
45 * reside as the data copied from the image. To prevent subsequent executions
46 * of the new image from undergoing the same relocations, any relocation entries
47 * (besides copy or jump slot relocations) are nulled out. Note that copy
48 * relocations such as required for __iob must be reinitialized each time the
49 * process starts, so it is not sufficient to simply null out the .dynamic
50 * sections relocation information. The effect of this is that if the new
51 * image was bound to definitions in any shared object dependencies, then these
52 * dependencies *must* reside in the same location as when dynodump(3x) was
53 * called. Any changes to the shared object dependencies of the new image, or
54 * uses of such things as LD_PRELOAD, may result in the bindings encoded in the
55 * image becoming invalid.
56 *
57 * The following flags modify the data of the image created:
58 *
59 * RTLD_SAVREL save the original relocation data. Under this option any
60 * relocation offset is reset to contain the same data as was
61 * found in the images original file.
62 *
63 * This option allows relocation information to be retained in the
64 * new image so that it may be re-executed when the new image is
65 * run. This allows far greater flexibility as the new image can
66 * now take advantage of new shared objects.
67 *
68 * Note. under this mechanism, any data item that undergoes
69 * relocation and is then further modified during the execution of
70 * the image before dynodump(3x) is called will lose the
71 * modification that occured during the applications execution.
72 *
73 * N.B. The above commentary is not quite correct in the flags have been hardwired
74 * to RTLD_SAVREL.
75 */
76 #pragma ident "@(#) $Id: dynodump.c,v 1.6 1998/03/31 20:10:55 steve Exp $ - SMI"
77
78 #define __EXTENSIONS__ 1
79
80 #include <sys/param.h>
81 #include <sys/procfs.h>
82 #include <fcntl.h>
83 #include <stdio.h>
84 #include <libelf.h>
85 #include <link.h>
86 #include <stdlib.h>
87 #include <string.h>
88 #include <unistd.h>
89 #include <errno.h>
90 #include <malloc.h>
91 #include "machdep.h"
92 #include "_dynodump.h"
93
94 /*
95 * Generic elf error message generator
96 */
97 static int
98 elferr(const char * str)
99 {
100 fprintf(stderr, "%s: %s\n", str, elf_errmsg(elf_errno()));
101 return (1);
102 }
103
104 int dynodump (const char * file);
105 int
106 dynodump(const char * file)
107 {
108 Elf *ielf, *oelf;
109 Ehdr *iehdr, *oehdr;
110 Phdr *iphdr, *ophdr, *data_phdr = 0;
111 Cache *icache, *ocache, *_icache, *_ocache;
112 Cache *data_cache = 0, *shstr_cache = 0;
113 Cache *heap_cache = 0;
114 Word heap_sz = 0;
115 Elf_Scn *scn;
116 Shdr *shdr;
117 Elf_Data *data, rundata;
118 Half ndx, _ndx;
119 int fd, _fd;
120 Addr edata, _addr;
121 char *istrs, *ostrs, *_ostrs, proc[16];
122 const char heap[] = ".heap";
123 prstatus_t pstat;
124
125 /* make a call to the processor specific un-init stuff */
126 dynodump_uninit();
127
128 /*
129 * Obtain a file descriptor for this process,
130 * for the executable and get a prstatus_t
131 * structure.
132 */
133 sprintf(proc, "/proc/%ld", getpid());
134 if (((_fd = open(proc, O_RDONLY, 0)) == -1) ||
135 ((fd = ioctl(_fd, PIOCOPENM, (void *)0)) == -1) ||
136 (ioctl(_fd, PIOCSTATUS, &pstat) == -1)) {
137 fprintf(stderr, "/proc: initialization error: %s\n",
138 strerror(errno));
139 close(_fd);
140 return (1);
141 }
142 close(_fd);
143
144 /*
145 * Initialize with the ELF library and make sure this is an executable
146 * ELF file we're dealing with.
147 */
148 elf_version(EV_CURRENT);
149 if ((ielf = elf_begin(fd, ELF_C_READ, NULL)) == NULL) {
150 close(fd);
151 return (elferr("elf_begin"));
152 }
153 close(fd);
154
155 if ((elf_kind(ielf) != ELF_K_ELF) ||
156 ((iehdr = elf_getehdr(ielf)) == NULL) ||
157 (iehdr->e_type != ET_EXEC)) {
158 fprintf(stderr, "image is not an ELF executable\n");
159 elf_end(ielf);
160 return (1);
161 }
162 /*
163 * Elf_elf_header(iehdr);
164 */
165
166 /*
167 * Create the new output file.
168 */
169 if ((fd = open(file, O_RDWR | O_CREAT | O_TRUNC, 0777)) == -1) {
170 fprintf(stderr, "%s: open failed: %s\n", file,
171 strerror(errno));
172 elf_end(ielf);
173 return (1);
174 }
175 if ((oelf = elf_begin(fd, ELF_C_WRITE, NULL)) == NULL) {
176 elf_end(ielf);
177 close(fd);
178 return (elferr("elf_begin"));
179 }
180
181 /*
182 * Obtain the input program headers. Remember the data segments
183 * program header entry as this will be updated later to reflect the
184 * new .heap sections size.
185 */
186 if ((iphdr = elf_getphdr(ielf)) == NULL)
187 return (elferr("elf_getphdr"));
188
189 for (ndx = 0, ophdr = iphdr; ndx != iehdr->e_phnum; ndx++, ophdr++) {
190 /*
191 * Save the program header that contains the NOBITS section, or
192 * the last loadable program header if no NOBITS exists.
193 * A NOBITS section translates to a memory size requirement that
194 * is greater than the file data it is mapped from.
195 */
196 if (ophdr->p_type == PT_LOAD) {
197 if (ophdr->p_filesz != ophdr->p_memsz)
198 data_phdr = ophdr;
199 else if (data_phdr) {
200 if (data_phdr->p_vaddr < ophdr->p_vaddr)
201 data_phdr = ophdr;
202 } else
203 data_phdr = ophdr;
204 }
205 }
206 if (data_phdr == 0) {
207 fprintf(stderr, "no data segment found!\n");
208 return (0);
209 }
210
211 /*
212 * Obtain the input files section header string table.
213 */
214 if ((scn = elf_getscn(ielf, iehdr->e_shstrndx)) == NULL)
215 return (elferr("elf_getscn"));
216 if ((data = elf_getdata(scn, NULL)) == NULL)
217 return (elferr("elf_getdata"));
218 istrs = (char *) data->d_buf;
219
220 /*
221 * Construct a cache to maintain the input files section information.
222 */
223 if ((icache = (Cache *) malloc(iehdr->e_shnum * sizeof (Cache))) == 0) {
224 fprintf(stderr, "malloc failed: %s\n", strerror(errno));
225 return (1);
226 }
227 _icache = icache;
228 _icache++;
229
230 /*
231 * Traverse each section from the input file.
232 */
233 for (ndx = 1, scn = 0;
234 (_icache->c_scn = elf_nextscn(ielf, scn));
235 ndx++, scn = _icache->c_scn, _icache++) {
236
237 if ((_icache->c_shdr = shdr = elf_getshdr(_icache->c_scn)) == NULL)
238 return (elferr("elf_getshdr"));
239
240 if ((_icache->c_data = elf_getdata(_icache->c_scn, NULL)) == NULL)
241 return (elferr("elf_getdata"));
242
243 _icache->c_name = istrs + (size_t)(shdr->sh_name);
244
245 /*
246 * For each section that has a virtual address reestablish the
247 * data buffer to point to the memory image.
248 *
249 * if (shdr->sh_addr)
250 * _icache->c_data->d_buf = (void *)shdr->sh_addr;
251 */
252
253 /*
254 * Remember the last section of the data segment, the new .heap
255 * section will be added after this section.
256 * If we already have one, then set data_cache to the previous
257 * section and set heap_cache to this one.
258 */
259 if ((shdr->sh_addr + shdr->sh_size)
260 == (data_phdr->p_vaddr + data_phdr->p_memsz)) {
261 if (strcmp(_icache->c_name, heap) == 0) {
262 #ifdef DEBUG
263 printf("Found a previous .heap section\n");
264 #endif
265 data_cache = _icache - 1;
266 heap_cache = _icache;
267 heap_sz = shdr->sh_size;
268 } else {
269 data_cache = _icache;
270 }
271 }
272
273 /*
274 * Remember the section header string table as this will be
275 * rewritten with the new .heap name.
276 */
277 if ((shdr->sh_type == SHT_STRTAB) &&
278 ((strcmp(_icache->c_name, ".shstrtab")) == 0))
279 shstr_cache = _icache;
280 }
281 if (data_cache == 0) {
282 fprintf(stderr, "final data section not found!\n");
283 return (0);
284 }
285
286 /*
287 * Determine the new .heap section to create.
288 */
289 rundata.d_buf = (void *)(data_cache->c_shdr->sh_addr +
290 data_cache->c_shdr->sh_size);
291 rundata.d_size = (int)sbrk(0) - (int)rundata.d_buf;
292 rundata.d_type = ELF_T_BYTE;
293 rundata.d_off = 0;
294 rundata.d_align = 1;
295 rundata.d_version = EV_CURRENT;
296
297 /*
298 * From the new data buffer determine the new value for _end and _edata.
299 * This will also be used to update the data segment program header.
300 *
301 * If we had a .heap section, then its size is part of the program
302 * headers notion of data size. Because we're only going to output one
303 * heap section (ignoring the one in the running binary) we need to
304 * subract the size of that which we're ignoring.
305 */
306 if (heap_cache) {
307 edata = S_ROUND((data_phdr->p_vaddr
308 + data_phdr->p_memsz
309 - heap_sz), rundata.d_align) + rundata.d_size;
310 } else {
311 edata = S_ROUND((data_phdr->p_vaddr + data_phdr->p_memsz),
312 rundata.d_align) + rundata.d_size;
313 }
314
315 /*
316 * We're now ready to construct the new elf image.
317 *
318 * Obtain a new elf header and initialize it with any basic information
319 * that isn't calculated as part of elf_update(). Bump the section
320 * header string table index to account for the .heap section we'll be
321 * adding.
322 */
323 if ((oehdr = elf_newehdr(oelf)) == NULL)
324 return (elferr("elf_newehdr"));
325
326 oehdr->e_entry = iehdr->e_entry;
327 oehdr->e_machine = iehdr->e_machine;
328 oehdr->e_type = iehdr->e_type;
329 oehdr->e_flags = iehdr->e_flags;
330 /*
331 * If we already have a heap section, we don't need any adjustment
332 */
333 if (heap_cache)
334 oehdr->e_shstrndx = iehdr->e_shstrndx;
335 else
336 oehdr->e_shstrndx = iehdr->e_shstrndx + 1;
337
338 #ifdef DEBUG
339 printf("iehdr->e_flags = %x\n", iehdr->e_flags);
340 printf("iehdr->e_entry = %x\n", iehdr->e_entry);
341 printf("iehdr->e_shstrndx= %d\n", iehdr->e_shstrndx);
342 printf("iehdr->e_machine = %d\n", iehdr->e_machine);
343 printf("iehdr->e_type = 0x%x\n", iehdr->e_type);
344 printf("oehdr->e_machine = %d\n", oehdr->e_machine);
345 printf("oehdr->e_type = 0x%x\n", oehdr->e_type);
346 #endif
347
348 /*
349 * Obtain a new set of program headers. Initialize these with the same
350 * information as the input program headers and update the data segment
351 * to reflect the new .heap section.
352 */
353 if ((ophdr = elf_newphdr(oelf, iehdr->e_phnum)) == NULL)
354 return (elferr("elf_newphdr"));
355
356 for (ndx = 0; ndx != iehdr->e_phnum; ndx++, iphdr++, ophdr++) {
357 *ophdr = *iphdr;
358 if (data_phdr == iphdr)
359 ophdr->p_filesz = ophdr->p_memsz = edata - ophdr->p_vaddr;
360 }
361
362 /*
363 * Obtain a new set of sections.
364 */
365 _icache = icache;
366 _icache++;
367 for (ndx = 1; ndx != iehdr->e_shnum; ndx++, _icache++) {
368 /*
369 * Skip the heap section of the running executable
370 */
371 if (_icache == heap_cache)
372 continue;
373 /*
374 * Create a matching section header in the output file.
375 */
376 if ((scn = elf_newscn(oelf)) == NULL)
377 return (elferr("elf_newscn"));
378 if ((shdr = elf_getshdr(scn)) == NULL)
379 return (elferr("elf_getshdr"));
380 *shdr = *_icache->c_shdr;
381
382 /*
383 * Create a matching data buffer for this section.
384 */
385 if ((data = elf_newdata(scn)) == NULL)
386 return (elferr("elf_newdata"));
387 *data = *_icache->c_data;
388
389 /*
390 * For each section that has a virtual address reestablish the
391 * data buffer to point to the memory image. Note, we skip
392 * the plt section.
393 */
394 if ((shdr->sh_addr) && (!((shdr->sh_type == SHT_PROGBITS)
395 && (strcmp(_icache->c_name, ".plt") == 0))))
396 data->d_buf = (void *)shdr->sh_addr;
397
398 /*
399 * Update any NOBITS section to indicate that it now contains
400 * data.
401 */
402 if (shdr->sh_type == SHT_NOBITS)
403 shdr->sh_type = SHT_PROGBITS;
404
405 /*
406 * Add the new .heap section after the last section of the
407 * present data segment. If we had a heap section, then
408 * this is the section preceding it.
409 */
410 if (data_cache == _icache) {
411 if ((scn = elf_newscn(oelf)) == NULL)
412 return (elferr("elf_newscn"));
413 if ((shdr = elf_getshdr(scn)) == NULL)
414 return (elferr("elf_getshdr"));
415 shdr->sh_type = SHT_PROGBITS;
416 shdr->sh_flags = SHF_ALLOC | SHF_WRITE;
417
418 if ((data = elf_newdata(scn)) == NULL)
419 return (elferr("elf_newdata"));
420 *data = rundata;
421 }
422
423 /*
424 * Update the section header string table size to reflect the
425 * new section name (only if we didn't already have a heap).
426 */
427 if (!heap_cache) {
428 if (shstr_cache && (shstr_cache == _icache)) {
429 data->d_size += sizeof (heap);
430 }
431 }
432 }
433
434 /*
435 * Write out the new image, and obtain a new elf descriptor that will
436 * allow us to write to the new image.
437 */
438 if (elf_update(oelf, ELF_C_WRITE) == -1)
439 return (elferr("elf_update"));
440 elf_end(oelf);
441 if ((oelf = elf_begin(fd, ELF_C_RDWR, NULL)) == NULL)
442 return (elferr("elf_begin"));
443 if ((oehdr = elf_getehdr(oelf)) == NULL)
444 return (elferr("elf_getehdr"));
445
446 /*
447 * Obtain the output files section header string table.
448 */
449 if ((scn = elf_getscn(oelf, oehdr->e_shstrndx)) == NULL)
450 return (elferr("elf_getscn"));
451 if ((data = elf_getdata(scn, NULL)) == NULL)
452 return (elferr("elf_getdata"));
453 ostrs = _ostrs = (char *) data->d_buf;
454 *_ostrs++ = '\0';
455
456 /*
457 * Construct a cache to maintain the output files section information.
458 */
459 if ((ocache = (Cache *)malloc(oehdr->e_shnum * sizeof (Cache))) == 0) {
460 fprintf(stderr, "malloc failed: %s\n", strerror(errno));
461 return (1);
462 }
463 _ocache = ocache;
464 _ocache++;
465 _icache = icache;
466 _icache++;
467
468 /*
469 * Traverse each section from the input file rebuilding the section
470 * header string table as we go.
471 */
472 _ndx = _addr = 0;
473 for (ndx = 1, scn = 0;
474 (_ocache->c_scn = elf_nextscn(oelf, scn));
475 ndx++, scn = _ocache->c_scn, _ocache++, _icache++) {
476
477 const char *strs;
478
479 if (_icache == heap_cache) {
480 #ifdef DEBUG
481 printf("ignoring .heap section in input\n");
482 #endif
483 _icache++;
484 }
485
486 if ((_ocache->c_shdr = shdr =
487 elf_getshdr(_ocache->c_scn)) == NULL)
488 return (elferr("elf_getshdr"));
489 if ((_ocache->c_data =
490 elf_getdata(_ocache->c_scn, NULL)) == NULL)
491 return (elferr("elf_getdata"));
492
493 /*
494 * If were inserting the new .heap section, insert the new
495 * section name and initialize its virtual address.
496 */
497 if (_addr) {
498 strs = heap;
499 shdr->sh_addr = S_ROUND(_addr, shdr->sh_addralign);
500 _addr = 0;
501 } else {
502 strs = istrs + (size_t)(_icache->c_shdr->sh_name);
503 }
504
505 strcpy(_ostrs, strs);
506 shdr->sh_name = _ostrs - ostrs;
507 _ocache->c_name = _ostrs;
508 _ostrs += strlen(strs) + 1;
509
510 /*
511 * If we've inserted a new section any later section may need
512 * their sh_link fields updated.
513 * If we already had a heap section, then this is not required.
514 */
515 if (!heap_cache) {
516 if (_ndx) {
517 if (_ocache->c_shdr->sh_link >= _ndx)
518 _ocache->c_shdr->sh_link++;
519 }
520 }
521
522 /*
523 * If this is the last section of the original data segment
524 * determine sufficient information to initialize the new .heap
525 * section which will be obtained next.
526 */
527 if (data_cache == _icache) {
528 _ndx = ndx + 1;
529 _addr = shdr->sh_addr + shdr->sh_size;
530 _icache--;
531 data_cache = 0;
532 }
533 }
534
535 /*
536 * Now that we have a complete description of the new image update any
537 * sections that are required.
538 *
539 * o update the value of _edata and _end.
540 *
541 * o reset any relocation entries if necessary.
542 */
543 _ocache = &ocache[1];
544 _icache = &icache[1];
545 for (ndx = 1; ndx < oehdr->e_shnum; ndx++, _ocache++, _icache++) {
546 if ((_ocache->c_shdr->sh_type == SHT_SYMTAB) ||
547 (_ocache->c_shdr->sh_type == SHT_DYNSYM))
548 update_sym(ocache, _ocache, edata);
549
550 if (_ocache->c_shdr->sh_type == M_REL_SHT_TYPE)
551 update_reloc(ocache, _ocache, icache, _icache, oehdr->e_shnum);
552 }
553
554 if (elf_update(oelf, ELF_C_WRITE) == -1)
555 return (elferr("elf_update"));
556
557 elf_end(oelf);
558 elf_end(ielf);
559 return (0);
560 }