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comparison dynodump/dynodump.c @ 0:376386a54a3c r19-14

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date Mon, 13 Aug 2007 08:45:50 +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 1.1.1.1 1996/12/18 03:37:22 steve Exp $ - SMI"
77
78 #include <sys/param.h>
79 #include <sys/procfs.h>
80 #include <fcntl.h>
81 #include <stdio.h>
82 #include <libelf.h>
83 #include <link.h>
84 #include <stdlib.h>
85 #include <string.h>
86 #include <unistd.h>
87 #include <errno.h>
88 #include <malloc.h>
89 #include "machdep.h"
90 #include "_dynodump.h"
91
92 /*
93 * Generic elf error message generator
94 */
95 static int
96 elferr(const char * str)
97 {
98 fprintf(stderr, "%s: %s\n", str, elf_errmsg(elf_errno()));
99 return (1);
100 }
101
102 int
103 dynodump(const char * file)
104 {
105 Elf *ielf, *oelf;
106 Ehdr *iehdr, *oehdr;
107 Phdr *iphdr, *ophdr, *data_phdr = 0;
108 Cache *icache, *ocache, *_icache, *_ocache;
109 Cache *data_cache = 0, *shstr_cache = 0;
110 Cache *heap_cache = 0;
111 Word heap_sz = 0;
112 Elf_Scn *scn;
113 Shdr *shdr;
114 Elf_Data *data, rundata;
115 Half ndx, _ndx;
116 int fd, _fd;
117 Addr edata, _addr;
118 char *istrs, *ostrs, *_ostrs, proc[16];
119 const char heap[] = ".heap";
120 prstatus_t pstat;
121
122 /* make a call to the processor specific un-init stuff */
123 dynodump_uninit();
124
125 /*
126 * Obtain a file descriptor for this process,
127 * for the executable and get a prstatus_t
128 * structure.
129 */
130 sprintf(proc, "/proc/%ld", getpid());
131 if (((_fd = open(proc, O_RDONLY, 0)) == -1) ||
132 ((fd = ioctl(_fd, PIOCOPENM, (void *)0)) == -1) ||
133 (ioctl(_fd, PIOCSTATUS, &pstat) == -1)) {
134 fprintf(stderr, "/proc: initialization error: %s\n",
135 strerror(errno));
136 close(_fd);
137 return (1);
138 }
139 close(_fd);
140
141 /*
142 * Initialize with the ELF library and make sure this is an executable
143 * ELF file we're dealing with.
144 */
145 elf_version(EV_CURRENT);
146 if ((ielf = elf_begin(fd, ELF_C_READ, NULL)) == NULL) {
147 close(fd);
148 return (elferr("elf_begin"));
149 }
150 close(fd);
151
152 if ((elf_kind(ielf) != ELF_K_ELF) ||
153 ((iehdr = elf_getehdr(ielf)) == NULL) ||
154 (iehdr->e_type != ET_EXEC)) {
155 fprintf(stderr, "image is not an ELF executable\n");
156 elf_end(ielf);
157 return (1);
158 }
159 /*
160 * Elf_elf_header(iehdr);
161 */
162
163 /*
164 * Create the new output file.
165 */
166 if ((fd = open(file, O_RDWR | O_CREAT | O_TRUNC, 0777)) == -1) {
167 fprintf(stderr, "%s: open failed: %s\n", file,
168 strerror(errno));
169 elf_end(ielf);
170 return (1);
171 }
172 if ((oelf = elf_begin(fd, ELF_C_WRITE, NULL)) == NULL) {
173 elf_end(ielf);
174 close(fd);
175 return (elferr("elf_begin"));
176 }
177
178 /*
179 * Obtain the input program headers. Remember the data segments
180 * program header entry as this will be updated later to reflect the
181 * new .heap sections size.
182 */
183 if ((iphdr = elf_getphdr(ielf)) == NULL)
184 return (elferr("elf_getphdr"));
185
186 for (ndx = 0, ophdr = iphdr; ndx != iehdr->e_phnum; ndx++, ophdr++) {
187 /*
188 * Save the program header that contains the NOBITS section, or
189 * the last loadable program header if no NOBITS exists.
190 * A NOBITS section translates to a memory size requirement that
191 * is greater than the file data it is mapped from.
192 */
193 if (ophdr->p_type == PT_LOAD) {
194 if (ophdr->p_filesz != ophdr->p_memsz)
195 data_phdr = ophdr;
196 else if (data_phdr) {
197 if (data_phdr->p_vaddr < ophdr->p_vaddr)
198 data_phdr = ophdr;
199 } else
200 data_phdr = ophdr;
201 }
202 }
203 if (data_phdr == 0) {
204 fprintf(stderr, "no data segment found!\n");
205 return (0);
206 }
207
208 /*
209 * Obtain the input files section header string table.
210 */
211 if ((scn = elf_getscn(ielf, iehdr->e_shstrndx)) == NULL)
212 return (elferr("elf_getscn"));
213 if ((data = elf_getdata(scn, NULL)) == NULL)
214 return (elferr("elf_getdata"));
215 istrs = data->d_buf;
216
217 /*
218 * Construct a cache to maintain the input files section information.
219 */
220 if ((icache = (Cache *) malloc(iehdr->e_shnum * sizeof (Cache))) == 0) {
221 fprintf(stderr, "malloc failed: %s\n", strerror(errno));
222 return (1);
223 }
224 _icache = icache;
225 _icache++;
226
227 /*
228 * Traverse each section from the input file.
229 */
230 for (ndx = 1, scn = 0;
231 _icache->c_scn = elf_nextscn(ielf, scn);
232 ndx++, scn = _icache->c_scn, _icache++) {
233
234 if ((_icache->c_shdr = shdr = elf_getshdr(_icache->c_scn)) == NULL)
235 return (elferr("elf_getshdr"));
236
237 if ((_icache->c_data = elf_getdata(_icache->c_scn, NULL)) == NULL)
238 return (elferr("elf_getdata"));
239
240 _icache->c_name = istrs + (size_t)(shdr->sh_name);
241
242 /*
243 * For each section that has a virtual address reestablish the
244 * data buffer to point to the memory image.
245 *
246 * if (shdr->sh_addr)
247 * _icache->c_data->d_buf = (void *)shdr->sh_addr;
248 */
249
250 /*
251 * Remember the last section of the data segment, the new .heap
252 * section will be added after this section.
253 * If we already have one, then set data_cache to the previous
254 * section and set heap_cache to this one.
255 */
256 if ((shdr->sh_addr + shdr->sh_size)
257 == (data_phdr->p_vaddr + data_phdr->p_memsz)) {
258 if (strcmp(_icache->c_name, heap) == 0) {
259 #ifdef DEBUG
260 printf("Found a previous .heap section\n");
261 #endif
262 data_cache = _icache - 1;
263 heap_cache = _icache;
264 heap_sz = shdr->sh_size;
265 } else {
266 data_cache = _icache;
267 }
268 }
269
270 /*
271 * Remember the section header string table as this will be
272 * rewritten with the new .heap name.
273 */
274 if ((shdr->sh_type == SHT_STRTAB) &&
275 ((strcmp(_icache->c_name, ".shstrtab")) == 0))
276 shstr_cache = _icache;
277 }
278 if (data_cache == 0) {
279 fprintf(stderr, "final data section not found!\n");
280 return (0);
281 }
282
283 /*
284 * Determine the new .heap section to create.
285 */
286 rundata.d_buf = (void *)(data_cache->c_shdr->sh_addr +
287 data_cache->c_shdr->sh_size);
288 rundata.d_size = (int)sbrk(0) - (int)rundata.d_buf;
289 rundata.d_type = ELF_T_BYTE;
290 rundata.d_off = 0;
291 rundata.d_align = 1;
292 rundata.d_version = EV_CURRENT;
293
294 /*
295 * From the new data buffer determine the new value for _end and _edata.
296 * This will also be used to update the data segment program header.
297 *
298 * If we had a .heap section, then its size is part of the program
299 * headers notion of data size. Because we're only going to output one
300 * heap section (ignoring the one in the running binary) we need to
301 * subract the size of that which we're ignoring.
302 */
303 if (heap_cache) {
304 edata = S_ROUND((data_phdr->p_vaddr
305 + data_phdr->p_memsz
306 - heap_sz), rundata.d_align) + rundata.d_size;
307 } else {
308 edata = S_ROUND((data_phdr->p_vaddr + data_phdr->p_memsz),
309 rundata.d_align) + rundata.d_size;
310 }
311
312 /*
313 * We're now ready to construct the new elf image.
314 *
315 * Obtain a new elf header and initialize it with any basic information
316 * that isn't calculated as part of elf_update(). Bump the section
317 * header string table index to account for the .heap section we'll be
318 * adding.
319 */
320 if ((oehdr = elf_newehdr(oelf)) == NULL)
321 return (elferr("elf_newehdr"));
322
323 oehdr->e_entry = iehdr->e_entry;
324 oehdr->e_machine = iehdr->e_machine;
325 oehdr->e_type = iehdr->e_type;
326 oehdr->e_flags = iehdr->e_flags;
327 /*
328 * If we already have a heap section, we don't need any adjustment
329 */
330 if (heap_cache)
331 oehdr->e_shstrndx = iehdr->e_shstrndx;
332 else
333 oehdr->e_shstrndx = iehdr->e_shstrndx + 1;
334
335 #ifdef DEBUG
336 printf("iehdr->e_flags = %x\n", iehdr->e_flags);
337 printf("iehdr->e_entry = %x\n", iehdr->e_entry);
338 printf("iehdr->e_shstrndx= %d\n", iehdr->e_shstrndx);
339 printf("iehdr->e_machine = %d\n", iehdr->e_machine);
340 printf("iehdr->e_type = 0x%x\n", iehdr->e_type);
341 printf("oehdr->e_machine = %d\n", oehdr->e_machine);
342 printf("oehdr->e_type = 0x%x\n", oehdr->e_type);
343 #endif
344
345 /*
346 * Obtain a new set of program headers. Initialize these with the same
347 * information as the input program headers and update the data segment
348 * to reflect the new .heap section.
349 */
350 if ((ophdr = elf_newphdr(oelf, iehdr->e_phnum)) == NULL)
351 return (elferr("elf_newphdr"));
352
353 for (ndx = 0; ndx != iehdr->e_phnum; ndx++, iphdr++, ophdr++) {
354 *ophdr = *iphdr;
355 if (data_phdr == iphdr)
356 ophdr->p_filesz = ophdr->p_memsz = edata - ophdr->p_vaddr;
357 }
358
359 /*
360 * Obtain a new set of sections.
361 */
362 _icache = icache;
363 _icache++;
364 for (ndx = 1; ndx != iehdr->e_shnum; ndx++, _icache++) {
365 /*
366 * Skip the heap section of the running executable
367 */
368 if (_icache == heap_cache)
369 continue;
370 /*
371 * Create a matching section header in the output file.
372 */
373 if ((scn = elf_newscn(oelf)) == NULL)
374 return (elferr("elf_newscn"));
375 if ((shdr = elf_getshdr(scn)) == NULL)
376 return (elferr("elf_getshdr"));
377 *shdr = *_icache->c_shdr;
378
379 /*
380 * Create a matching data buffer for this section.
381 */
382 if ((data = elf_newdata(scn)) == NULL)
383 return (elferr("elf_newdata"));
384 *data = *_icache->c_data;
385
386 /*
387 * For each section that has a virtual address reestablish the
388 * data buffer to point to the memory image. Note, we skip
389 * the plt section.
390 */
391 if ((shdr->sh_addr) && (!((shdr->sh_type == SHT_PROGBITS)
392 && (strcmp(_icache->c_name, ".plt") == 0))))
393 data->d_buf = (void *)shdr->sh_addr;
394
395 /*
396 * Update any NOBITS section to indicate that it now contains
397 * data.
398 */
399 if (shdr->sh_type == SHT_NOBITS)
400 shdr->sh_type = SHT_PROGBITS;
401
402 /*
403 * Add the new .heap section after the last section of the
404 * present data segment. If we had a heap section, then
405 * this is the section preceding it.
406 */
407 if (data_cache == _icache) {
408 if ((scn = elf_newscn(oelf)) == NULL)
409 return (elferr("elf_newscn"));
410 if ((shdr = elf_getshdr(scn)) == NULL)
411 return (elferr("elf_getshdr"));
412 shdr->sh_type = SHT_PROGBITS;
413 shdr->sh_flags = SHF_ALLOC | SHF_WRITE;
414
415 if ((data = elf_newdata(scn)) == NULL)
416 return (elferr("elf_newdata"));
417 *data = rundata;
418 }
419
420 /*
421 * Update the section header string table size to reflect the
422 * new section name (only if we didn't already have a heap).
423 */
424 if (!heap_cache) {
425 if (shstr_cache && (shstr_cache == _icache)) {
426 data->d_size += sizeof (heap);
427 }
428 }
429 }
430
431 /*
432 * Write out the new image, and obtain a new elf descriptor that will
433 * allow us to write to the new image.
434 */
435 if (elf_update(oelf, ELF_C_WRITE) == -1)
436 return (elferr("elf_update"));
437 elf_end(oelf);
438 if ((oelf = elf_begin(fd, ELF_C_RDWR, NULL)) == NULL)
439 return (elferr("elf_begin"));
440 if ((oehdr = elf_getehdr(oelf)) == NULL)
441 return (elferr("elf_getehdr"));
442
443 /*
444 * Obtain the output files section header string table.
445 */
446 if ((scn = elf_getscn(oelf, oehdr->e_shstrndx)) == NULL)
447 return (elferr("elf_getscn"));
448 if ((data = elf_getdata(scn, NULL)) == NULL)
449 return (elferr("elf_getdata"));
450 ostrs = _ostrs = data->d_buf;
451 *_ostrs++ = '\0';
452
453 /*
454 * Construct a cache to maintain the output files section information.
455 */
456 if ((ocache = (Cache *)malloc(oehdr->e_shnum * sizeof (Cache))) == 0) {
457 fprintf(stderr, "malloc failed: %s\n", strerror(errno));
458 return (1);
459 }
460 _ocache = ocache;
461 _ocache++;
462 _icache = icache;
463 _icache++;
464
465 /*
466 * Traverse each section from the input file rebuilding the section
467 * header string table as we go.
468 */
469 _ndx = _addr = 0;
470 for (ndx = 1, scn = 0;
471 _ocache->c_scn = elf_nextscn(oelf, scn);
472 ndx++, scn = _ocache->c_scn, _ocache++, _icache++) {
473
474 const char *strs;
475
476 if (_icache == heap_cache) {
477 #ifdef DEBUG
478 printf("ignoring .heap section in input\n");
479 #endif
480 _icache++;
481 }
482
483 if ((_ocache->c_shdr = shdr =
484 elf_getshdr(_ocache->c_scn)) == NULL)
485 return (elferr("elf_getshdr"));
486 if ((_ocache->c_data =
487 elf_getdata(_ocache->c_scn, NULL)) == NULL)
488 return (elferr("elf_getdata"));
489
490 /*
491 * If were inserting the new .heap section, insert the new
492 * section name and initialize it's virtual address.
493 */
494 if (_addr) {
495 strs = heap;
496 shdr->sh_addr = S_ROUND(_addr, shdr->sh_addralign);
497 _addr = 0;
498 } else {
499 strs = istrs + (size_t)(_icache->c_shdr->sh_name);
500 }
501
502 strcpy(_ostrs, strs);
503 shdr->sh_name = _ostrs - ostrs;
504 _ocache->c_name = _ostrs;
505 _ostrs += strlen(strs) + 1;
506
507 /*
508 * If we've inserted a new section any later section may need
509 * their sh_link fields updated.
510 * If we already had a heap section, then this is not required.
511 */
512 if (!heap_cache) {
513 if (_ndx) {
514 if (_ocache->c_shdr->sh_link >= _ndx)
515 _ocache->c_shdr->sh_link++;
516 }
517 }
518
519 /*
520 * If this is the last section of the original data segment
521 * determine sufficient information to initialize the new .heap
522 * section which will be obtained next.
523 */
524 if (data_cache == _icache) {
525 _ndx = ndx + 1;
526 _addr = shdr->sh_addr + shdr->sh_size;
527 _icache--;
528 data_cache = 0;
529 }
530 }
531
532 /*
533 * Now that we have a complete description of the new image update any
534 * sections that are required.
535 *
536 * o update the value of _edata and _end.
537 *
538 * o reset any relocation entries if necessary.
539 */
540 _ocache = &ocache[1];
541 _icache = &icache[1];
542 for (ndx = 1; ndx < oehdr->e_shnum; ndx++, _ocache++, _icache++) {
543 if ((_ocache->c_shdr->sh_type == SHT_SYMTAB) ||
544 (_ocache->c_shdr->sh_type == SHT_DYNSYM))
545 update_sym(ocache, _ocache, edata);
546
547 if (_ocache->c_shdr->sh_type == M_REL_SHT_TYPE)
548 update_reloc(ocache, _ocache, icache, _icache, oehdr->e_shnum);
549 }
550
551 if (elf_update(oelf, ELF_C_WRITE) == -1)
552 return (elferr("elf_update"));
553
554 elf_end(oelf);
555 elf_end(ielf);
556 return (0);
557 }