1/*-
2 * Copyright (c) 2006 Joseph Koshy
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27
28#include <sys/mman.h>
29#include <sys/param.h>
30
31#include <assert.h>
32#include <errno.h>
33#include "gelf.h"
34#include "libelf.h"
35#include <stdlib.h>
36#include <string.h>
37#include <unistd.h>
38
39#include "_libelf.h"
40
41/*
42 * Update the internal data structures associated with an ELF object.
43 * Returns the size in bytes the ELF object would occupy in its file
44 * representation.
45 *
46 * After a successful call to this function, the following structures
47 * are updated:
48 *
49 * - The ELF header is updated.
50 * - All sections are sorted in order of ascending addresses and their
51 * section header table entries updated. An error is signalled
52 * if an overlap was detected among sections.
53 * - All data descriptors associated with a section are sorted in order
54 * of ascending addresses. Overlaps, if detected, are signalled as
55 * errors. Other sanity checks for alignments, section types etc. are
56 * made.
57 *
58 * After a resync_elf() successfully returns, the ELF descriptor is
59 * ready for being handed over to _libelf_write_elf().
60 *
61 * File alignments:
62 * PHDR - Addr
63 * SHDR - Addr
64 *
65 * XXX: how do we handle 'flags'.
66 */
67
68/*
69 * Compute the extents of a section, by looking at the.
70 */
71static int
72_libelf_compute_section_extents(Elf *e, Elf_Scn *s, off_t *rc)
73{
74 int ec;
75 Elf_Data *d, *td;
76 unsigned int elftype;
77 uint32_t sh_type;
78 uint64_t d_align;
79 uint64_t sh_align, sh_entsize, sh_offset, sh_size;
80 uint64_t scn_size, scn_alignment;
81
82 /*
83 * We need to recompute library private data structures if one
84 * or more of the following is true:
85 * - The underlying Shdr structure has been marked `dirty'. Significant
86 * fields include: `sh_offset', `sh_type', `sh_size', `sh_addralign'.
87 * - The Elf_Data structures part of this section have been marked
88 * `dirty'. Affected members include `d_align', `d_offset', `d_type',
89 * and `d_size'.
90 * - The section as a whole is `dirty', e.g., it has been allocated
91 * using elf_newscn(), or if a new Elf_Data structure was added using
92 * elf_newdata().
93 *
94 * Each of these conditions would result in the ELF_F_DIRTY bit being
95 * set on the section descriptor's `s_flags' field.
96 */
97
98 ec = e->e_class;
99
100 if (ec == ELFCLASS32) {
101 sh_type = s->s_shdr.s_shdr32.sh_type;
102 sh_align = (uint64_t) s->s_shdr.s_shdr32.sh_addralign;
103 sh_entsize = (uint64_t) s->s_shdr.s_shdr32.sh_entsize;
104 sh_offset = (uint64_t) s->s_shdr.s_shdr32.sh_offset;
105 sh_size = (uint64_t) s->s_shdr.s_shdr32.sh_size;
106 } else {
107 sh_type = s->s_shdr.s_shdr64.sh_type;
108 sh_align = s->s_shdr.s_shdr64.sh_addralign;
109 sh_entsize = s->s_shdr.s_shdr64.sh_entsize;
110 sh_offset = s->s_shdr.s_shdr64.sh_offset;
111 sh_size = s->s_shdr.s_shdr64.sh_size;
112 }
113
114 if (sh_type == SHT_NULL || sh_type == SHT_NOBITS)
115 return (1);
116
117 if ((s->s_flags & ELF_F_DIRTY) == 0) {
118 if ((size_t) *rc < sh_offset + sh_size)
119 *rc = sh_offset + sh_size;
120 return (1);
121 }
122
123 elftype = _libelf_xlate_shtype(sh_type);
124 if (elftype > ELF_T_LAST) {
125 LIBELF_SET_ERROR(SECTION, 0);
126 return (0);
127 }
128
129 /*
130 * Compute the extent of the data descriptors associated with
131 * this section.
132 */
133 scn_alignment = 0;
134 if (sh_align == 0)
135 sh_align = _libelf_falign(elftype, ec);
136
137 /* Compute the section alignment. */
138 STAILQ_FOREACH(d, &s->s_data, d_next) {
139 if (d->d_type != elftype) {
140 LIBELF_SET_ERROR(DATA, 0);
141 return (0);
142 }
143 if (d->d_version != e->e_version) {
144 LIBELF_SET_ERROR(VERSION, 0);
145 return (0);
146 }
147 if ((d_align = d->d_align) % sh_align) {
148 LIBELF_SET_ERROR(LAYOUT, 0);
149 return (0);
150 }
151 if (d_align == 0 || (d_align & (d_align - 1))) {
152 LIBELF_SET_ERROR(DATA, 0);
153 return (0);
154 }
155 if (d_align > scn_alignment)
156 scn_alignment = d_align;
157 }
158
159 scn_size = 0L;
160
161 STAILQ_FOREACH_SAFE(d, &s->s_data, d_next, td) {
162 if (e->e_flags & ELF_F_LAYOUT) {
163 if ((uint64_t) d->d_off + d->d_size > scn_size)
164 scn_size = d->d_off + d->d_size;
165 } else {
166 scn_size = roundup(scn_size, scn_alignment);
167 d->d_off = scn_size;
168 scn_size += d->d_size;
169 }
170 }
171
172 /*
173 * If the application is requesting full control over the layout
174 * of the section, check its values for sanity.
175 */
176 if (e->e_flags & ELF_F_LAYOUT) {
177 if (scn_alignment > sh_align || sh_offset % sh_align ||
178 sh_size < scn_size) {
179 LIBELF_SET_ERROR(LAYOUT, 0);
180 return (0);
181 }
182 } else {
183 /*
184 * Otherwise compute the values in the section header.
185 */
186
187 if (scn_alignment > sh_align)
188 sh_align = scn_alignment;
189
190 /*
191 * If the section entry size is zero, try and fill in an
192 * appropriate entry size. Per the elf(5) manual page
193 * sections without fixed-size entries should have their
194 * 'sh_entsize' field set to zero.
195 */
196 if (sh_entsize == 0 &&
197 (sh_entsize = _libelf_fsize(elftype, ec, e->e_version,
198 (size_t) 1)) == 1)
199 sh_entsize = 0;
200
201 sh_size = scn_size;
202 sh_offset = roundup(*rc, sh_align);
203
204 if (ec == ELFCLASS32) {
205 s->s_shdr.s_shdr32.sh_addralign = (uint32_t) sh_align;
206 s->s_shdr.s_shdr32.sh_entsize = (uint32_t) sh_entsize;
207 s->s_shdr.s_shdr32.sh_offset = (uint32_t) sh_offset;
208 s->s_shdr.s_shdr32.sh_size = (uint32_t) sh_size;
209 } else {
210 s->s_shdr.s_shdr64.sh_addralign = sh_align;
211 s->s_shdr.s_shdr64.sh_entsize = sh_entsize;
212 s->s_shdr.s_shdr64.sh_offset = sh_offset;
213 s->s_shdr.s_shdr64.sh_size = sh_size;
214 }
215 }
216
217 if ((size_t) *rc < sh_offset + sh_size)
218 *rc = sh_offset + sh_size;
219
220 s->s_size = sh_size;
221 s->s_offset = sh_offset;
222 return (1);
223}
224
225
226/*
227 * Insert a section in ascending order in the list
228 */
229
230static int
231_libelf_insert_section(Elf *e, Elf_Scn *s)
232{
233 Elf_Scn *t, *prevt;
234 uint64_t smax, smin, tmax, tmin;
235
236 smin = s->s_offset;
237 smax = smin + s->s_size;
238
239 prevt = NULL;
240 STAILQ_FOREACH(t, &e->e_u.e_elf.e_scn, s_next) {
241 tmin = t->s_offset;
242 tmax = tmin + t->s_size;
243
244 /* check if there is an overlap */
245 if (tmax < smin) {
246 prevt = t;
247 continue;
248 } else if (smax < tmin)
249 break;
250 else {
251 LIBELF_SET_ERROR(LAYOUT, 0);
252 return (0);
253 }
254 }
255
256 if (prevt)
257 STAILQ_INSERT_AFTER(&e->e_u.e_elf.e_scn, prevt, s, s_next);
258 else
259 STAILQ_INSERT_HEAD(&e->e_u.e_elf.e_scn, s, s_next);
260 return (1);
261}
262
263static off_t
264_libelf_resync_sections(Elf *e, off_t rc)
265{
266 int ec;
267 off_t nrc;
268 size_t sh_type;
269 Elf_Scn *s, *ts;
270
271 ec = e->e_class;
272
273 /*
274 * Make a pass through sections, computing the extent of each
275 * section. Order in increasing order of addresses.
276 */
277
278 nrc = rc;
279 STAILQ_FOREACH(s, &e->e_u.e_elf.e_scn, s_next)
280 if (_libelf_compute_section_extents(e, s, &nrc) == 0)
281 return ((off_t) -1);
282
283 STAILQ_FOREACH_SAFE(s, &e->e_u.e_elf.e_scn, s_next, ts) {
284 if (ec == ELFCLASS32)
285 sh_type = s->s_shdr.s_shdr32.sh_type;
286 else
287 sh_type = s->s_shdr.s_shdr64.sh_type;
288
289 /* XXX Do we need the 'size' field of an SHT_NOBITS section */
290 if (sh_type == SHT_NOBITS || sh_type == SHT_NULL)
291 continue;
292
293 if (s->s_offset < (uint64_t) rc) {
294 if (s->s_offset + s->s_size < (uint64_t) rc) {
295 /*
296 * Try insert this section in the
297 * correct place in the list,
298 * detecting overlaps if any.
299 */
300 STAILQ_REMOVE(&e->e_u.e_elf.e_scn, s, _Elf_Scn,
301 s_next);
302 if (_libelf_insert_section(e, s) == 0)
303 return ((off_t) -1);
304 } else {
305 LIBELF_SET_ERROR(LAYOUT, 0);
306 return ((off_t) -1);
307 }
308 } else
309 rc = s->s_offset + s->s_size;
310 }
311
312 assert(nrc == rc);
313
314 return (rc);
315}
316
317static off_t
318_libelf_resync_elf(Elf *e)
319{
320 int ec, eh_class, eh_type;
321 unsigned int eh_byteorder, eh_version;
322 size_t align, fsz;
323 size_t phnum, shnum;
324 off_t rc, phoff, shoff;
325 void *ehdr;
326 Elf32_Ehdr *eh32;
327 Elf64_Ehdr *eh64;
328
329 rc = 0;
330
331 ec = e->e_class;
332
333 assert(ec == ELFCLASS32 || ec == ELFCLASS64);
334
335 /*
336 * Prepare the EHDR.
337 */
338 if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL)
339 return ((off_t) -1);
340
341 eh32 = ehdr;
342 eh64 = ehdr;
343
344 if (ec == ELFCLASS32) {
345 eh_byteorder = eh32->e_ident[EI_DATA];
346 eh_class = eh32->e_ident[EI_CLASS];
347 phoff = (uint64_t) eh32->e_phoff;
348 shoff = (uint64_t) eh32->e_shoff;
349 eh_type = eh32->e_type;
350 eh_version = eh32->e_version;
351 } else {
352 eh_byteorder = eh64->e_ident[EI_DATA];
353 eh_class = eh64->e_ident[EI_CLASS];
354 phoff = eh64->e_phoff;
355 shoff = eh64->e_shoff;
356 eh_type = eh64->e_type;
357 eh_version = eh64->e_version;
358 }
359
360 if (eh_version == EV_NONE)
361 eh_version = EV_CURRENT;
362
363 if (eh_version != e->e_version) { /* always EV_CURRENT */
364 LIBELF_SET_ERROR(VERSION, 0);
365 return ((off_t) -1);
366 }
367
368 if (eh_class != e->e_class) {
369 LIBELF_SET_ERROR(CLASS, 0);
370 return ((off_t) -1);
371 }
372
373 if (e->e_cmd != ELF_C_WRITE && eh_byteorder != e->e_byteorder) {
374 LIBELF_SET_ERROR(HEADER, 0);
375 return ((off_t) -1);
376 }
377
378 shnum = e->e_u.e_elf.e_nscn;
379 phnum = e->e_u.e_elf.e_nphdr;
380
381 e->e_byteorder = eh_byteorder;
382
383#define INITIALIZE_EHDR(E,EC,V) do { \
384 (E)->e_ident[EI_MAG0] = ELFMAG0; \
385 (E)->e_ident[EI_MAG1] = ELFMAG1; \
386 (E)->e_ident[EI_MAG2] = ELFMAG2; \
387 (E)->e_ident[EI_MAG3] = ELFMAG3; \
388 (E)->e_ident[EI_CLASS] = (EC); \
389 (E)->e_ident[EI_VERSION] = (V); \
390 (E)->e_ehsize = _libelf_fsize(ELF_T_EHDR, (EC), (V), \
391 (size_t) 1); \
392 (E)->e_phentsize = _libelf_fsize(ELF_T_PHDR, (EC), (V), \
393 (size_t) 1); \
394 (E)->e_shentsize = _libelf_fsize(ELF_T_SHDR, (EC), (V), \
395 (size_t) 1); \
396 } while (0)
397
398 if (ec == ELFCLASS32)
399 INITIALIZE_EHDR(eh32, ec, eh_version);
400 else
401 INITIALIZE_EHDR(eh64, ec, eh_version);
402
403 (void) elf_flagehdr(e, ELF_C_SET, ELF_F_DIRTY);
404
405 rc += _libelf_fsize(ELF_T_EHDR, ec, eh_version, (size_t) 1);
406
407 /*
408 * Compute the layout the program header table, if one is
409 * present. The program header table needs to be aligned to a
410 * `natural' boundary.
411 */
412 if (phnum) {
413 fsz = _libelf_fsize(ELF_T_PHDR, ec, eh_version, phnum);
414 align = _libelf_falign(ELF_T_PHDR, ec);
415
416 if (e->e_flags & ELF_F_LAYOUT) {
417 /*
418 * Check offsets for sanity.
419 */
420 if (rc > phoff) {
421 LIBELF_SET_ERROR(HEADER, 0);
422 return ((off_t) -1);
423 }
424
425 if (phoff % align) {
426 LIBELF_SET_ERROR(LAYOUT, 0);
427 return ((off_t) -1);
428 }
429
430 } else
431 phoff = roundup(rc, align);
432
433 rc = phoff + fsz;
434 } else
435 phoff = 0;
436
437 /*
438 * Compute the layout of the sections associated with the
439 * file.
440 */
441
442 if ((rc = _libelf_resync_sections(e, rc)) < 0)
443 return ((off_t) -1);
444
445 /*
446 * Compute the space taken up by the section header table, if
447 * one is needed.
448 */
449 if (shnum) {
450 fsz = _libelf_fsize(ELF_T_SHDR, ec, eh_version, (size_t) 1);
451 align = _libelf_falign(ELF_T_SHDR, ec);
452
453 if (e->e_flags & ELF_F_LAYOUT) {
454 if (rc > shoff) {
455 LIBELF_SET_ERROR(HEADER, 0);
456 return ((off_t) -1);
457 }
458
459 if (shoff % align) {
460 LIBELF_SET_ERROR(LAYOUT, 0);
461 return ((off_t) -1);
462 }
463 } else
464 shoff = roundup(rc, align);
465
466 rc = shoff + fsz * shnum;
467 } else
468 shoff = 0;
469
470 /*
471 * Set the fields of the Executable Header that could potentially use
472 * extended numbering.
473 */
474 _libelf_setphnum(e, ehdr, ec, phnum);
475 _libelf_setshnum(e, ehdr, ec, shnum);
476
477 /*
478 * Update the `e_phoff' and `e_shoff' fields if the library is
479 * doing the layout.
480 */
481 if ((e->e_flags & ELF_F_LAYOUT) == 0) {
482 if (ec == ELFCLASS32) {
483 eh32->e_phoff = (uint32_t) phoff;
484 eh32->e_shoff = (uint32_t) shoff;
485 } else {
486 eh64->e_phoff = (uint64_t) phoff;
487 eh64->e_shoff = (uint64_t) shoff;
488 }
489 }
490
491 return (rc);
492}
493
494/*
495 * Write out the contents of a section.
496 */
497
498static off_t
499_libelf_write_scn(Elf *e, char *nf, Elf_Scn *s, off_t rc)
500{
501 int ec;
502 size_t fsz, msz, nobjects;
503 uint32_t sh_type;
504 uint64_t sh_off;
505 int elftype;
506 Elf_Data *d, dst;
507
508 if ((ec = e->e_class) == ELFCLASS32)
509 sh_type = s->s_shdr.s_shdr32.sh_type;
510 else
511 sh_type = s->s_shdr.s_shdr64.sh_type;
512
513 /*
514 * Ignore sections that do not allocate space in the file.
515 */
516 if (sh_type == SHT_NOBITS || sh_type == SHT_NULL)
517 return (rc);
518
519
520 elftype = _libelf_xlate_shtype(sh_type);
521 assert(elftype >= ELF_T_FIRST && elftype <= ELF_T_LAST);
522
523 msz = _libelf_msize(elftype, ec, e->e_version);
524
525 sh_off = s->s_offset;
526 assert(sh_off % _libelf_falign(elftype, ec) == 0);
527
528 /*
529 * If the section has a `rawdata' descriptor, and the section
530 * contents have not been modified, use its contents directly.
531 * The `s_rawoff' member contains the offset into the original
532 * file, while `s_offset' contains its new location in the
533 * destination.
534 */
535
536 if (STAILQ_EMPTY(&s->s_data)) {
537
538 if ((d = elf_rawdata(s, NULL)) == NULL)
539 return ((off_t) -1);
540
541 STAILQ_FOREACH(d, &s->s_rawdata, d_next) {
542 if ((uint64_t) rc < sh_off + d->d_off)
543 (void) memset(nf + rc,
544 LIBELF_PRIVATE(fillchar), sh_off +
545 d->d_off - rc);
546 rc = sh_off + d->d_off;
547
548 assert(d->d_buf != NULL);
549 assert(d->d_type == ELF_T_BYTE);
550 assert(d->d_version == e->e_version);
551
552 (void) memcpy(nf + rc,
553 e->e_rawfile + s->s_rawoff + d->d_off, d->d_size);
554
555 rc += d->d_size;
556 }
557
558 return (rc);
559 }
560
561 /*
562 * Iterate over the set of data descriptors for this section.
563 * The prior call to _libelf_resync_elf() would have setup the
564 * descriptors for this step.
565 */
566
567 dst.d_version = e->e_version;
568
569 STAILQ_FOREACH(d, &s->s_data, d_next) {
570
571 if ((uint64_t) rc < sh_off + d->d_off)
572 (void) memset(nf + rc,
573 LIBELF_PRIVATE(fillchar), sh_off + d->d_off - rc);
574
575 rc = sh_off + d->d_off;
576
577 assert(d->d_buf != NULL);
578 assert(d->d_type == (Elf_Type) elftype);
579 assert(d->d_version == e->e_version);
580 assert(d->d_size % msz == 0);
581
582 nobjects = d->d_size / msz;
583
584 fsz = _libelf_fsize(elftype, ec, e->e_version, nobjects);
585
586 dst.d_buf = nf + rc;
587 dst.d_size = fsz;
588
589 if (_libelf_xlate(&dst, d, e->e_byteorder, ec, ELF_TOFILE) ==
590 NULL)
591 return ((off_t) -1);
592
593 rc += fsz;
594 }
595
596 return ((off_t) rc);
597}
598
599/*
600 * Write out the file image.
601 *
602 * The original file could have been mapped in with an ELF_C_RDWR
603 * command and the application could have added new content or
604 * re-arranged its sections before calling elf_update(). Consequently
605 * its not safe to work `in place' on the original file. So we
606 * malloc() the required space for the updated ELF object and build
607 * the object there and write it out to the underlying file at the
608 * end. Note that the application may have opened the underlying file
609 * in ELF_C_RDWR and only retrieved/modified a few sections. We take
610 * care to avoid translating file sections unnecessarily.
611 *
612 * Gaps in the coverage of the file by the file's sections will be
613 * filled with the fill character set by elf_fill(3).
614 */
615
616static off_t
617_libelf_write_elf(Elf *e, off_t newsize)
618{
619 int ec;
620 off_t rc;
621 size_t fsz, msz, phnum, shnum;
622 uint64_t phoff, shoff;
623 void *ehdr;
624 char *newfile;
625 Elf_Data dst, src;
626 Elf_Scn *scn, *tscn;
627 Elf32_Ehdr *eh32;
628 Elf64_Ehdr *eh64;
629
630 assert(e->e_kind == ELF_K_ELF);
631 assert(e->e_cmd != ELF_C_READ);
632 assert(e->e_fd >= 0);
633
634 if ((newfile = malloc((size_t) newsize)) == NULL) {
635 LIBELF_SET_ERROR(RESOURCE, errno);
636 return ((off_t) -1);
637 }
638
639 ec = e->e_class;
640
641 ehdr = _libelf_ehdr(e, ec, 0);
642 assert(ehdr != NULL);
643
644 phnum = e->e_u.e_elf.e_nphdr;
645
646 if (ec == ELFCLASS32) {
647 eh32 = (Elf32_Ehdr *) ehdr;
648
649 phoff = (uint64_t) eh32->e_phoff;
650 shnum = eh32->e_shnum;
651 shoff = (uint64_t) eh32->e_shoff;
652 } else {
653 eh64 = (Elf64_Ehdr *) ehdr;
654
655 phoff = eh64->e_phoff;
656 shnum = eh64->e_shnum;
657 shoff = eh64->e_shoff;
658 }
659
660 fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1);
661 msz = _libelf_msize(ELF_T_EHDR, ec, e->e_version);
662
663 (void) memset(&dst, 0, sizeof(dst));
664 (void) memset(&src, 0, sizeof(src));
665
666 src.d_buf = ehdr;
667 src.d_size = msz;
668 src.d_type = ELF_T_EHDR;
669 src.d_version = dst.d_version = e->e_version;
670
671 rc = 0;
672
673 dst.d_buf = newfile + rc;
674 dst.d_size = fsz;
675
676 if (_libelf_xlate(&dst, &src, e->e_byteorder, ec, ELF_TOFILE) ==
677 NULL)
678 goto error;
679
680 rc += fsz;
681
682 /*
683 * Write the program header table if present.
684 */
685
686 if (phnum != 0 && phoff != 0) {
687 assert((unsigned) rc <= phoff);
688
689 fsz = _libelf_fsize(ELF_T_PHDR, ec, e->e_version, phnum);
690
691 assert(phoff % _libelf_falign(ELF_T_PHDR, ec) == 0);
692 assert(fsz > 0);
693
694 src.d_version = dst.d_version = e->e_version;
695 src.d_type = ELF_T_PHDR;
696
697 if (ec == ELFCLASS32)
698 src.d_buf = e->e_u.e_elf.e_phdr.e_phdr32;
699 else
700 src.d_buf = e->e_u.e_elf.e_phdr.e_phdr64;
701
702 src.d_size = phnum * _libelf_msize(ELF_T_PHDR, ec,
703 e->e_version);
704
705 dst.d_size = fsz;
706
707 if ((uint64_t) rc < phoff)
708 (void) memset(newfile + rc,
709 LIBELF_PRIVATE(fillchar), phoff - rc);
710
711 dst.d_buf = newfile + rc;
712
713 if (_libelf_xlate(&dst, &src, e->e_byteorder, ec, ELF_TOFILE) ==
714 NULL)
715 goto error;
716
717 rc = phoff + fsz;
718 }
719
720 /*
721 * Write out individual sections.
722 */
723
724 STAILQ_FOREACH(scn, &e->e_u.e_elf.e_scn, s_next)
725 if ((rc = _libelf_write_scn(e, newfile, scn, rc)) < 0)
726 goto error;
727
728 /*
729 * Write out the section header table, if required.
730 */
731
732 if (shnum != 0 && shoff != 0) {
733 assert((unsigned) rc <= shoff);
734
735 if ((uint64_t) rc < shoff)
736 (void) memset(newfile + rc,
737 LIBELF_PRIVATE(fillchar), shoff - rc);
738
739 rc = shoff;
740
741 assert(rc % _libelf_falign(ELF_T_SHDR, ec) == 0);
742
743 src.d_type = ELF_T_SHDR;
744 src.d_size = _libelf_msize(ELF_T_SHDR, ec, e->e_version);
745 src.d_version = dst.d_version = e->e_version;
746
747 fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, (size_t) 1);
748
749 STAILQ_FOREACH(scn, &e->e_u.e_elf.e_scn, s_next) {
750 if (ec == ELFCLASS32)
751 src.d_buf = &scn->s_shdr.s_shdr32;
752 else
753 src.d_buf = &scn->s_shdr.s_shdr64;
754
755 dst.d_size = fsz;
756 dst.d_buf = newfile + rc;
757
758 if (_libelf_xlate(&dst, &src, e->e_byteorder, ec,
759 ELF_TOFILE) != &dst)
760 goto error;
761
762 rc += fsz;
763 }
764 }
765
766 /*
767 */
768
769 assert(rc == newsize);
770
771 /*
772 * Write out the constructed contents and remap the file in
773 * read-only.
774 */
775
776 if (e->e_rawfile && munmap(e->e_rawfile, e->e_rawsize) < 0) {
777 LIBELF_SET_ERROR(IO, errno);
778 goto error;
779 }
780
781 if (write(e->e_fd, newfile, (size_t) newsize) != newsize ||
782 lseek(e->e_fd, (off_t) 0, SEEK_SET) < 0) {
783 LIBELF_SET_ERROR(IO, errno);
784 goto error;
785 }
786
787 if (e->e_cmd != ELF_C_WRITE) {
788 if ((e->e_rawfile = mmap(NULL, (size_t) newsize, PROT_READ,
789 MAP_PRIVATE, e->e_fd, (off_t) 0)) == MAP_FAILED) {
790 LIBELF_SET_ERROR(IO, errno);
791 goto error;
792 }
793 e->e_rawsize = newsize;
794 }
795
796 /*
797 * Reset flags, remove existing section descriptors and
798 * {E,P}HDR pointers so that a subsequent elf_get{e,p}hdr()
799 * and elf_getscn() will function correctly.
800 */
801
802 e->e_flags &= ~ELF_F_DIRTY;
803
804 STAILQ_FOREACH_SAFE(scn, &e->e_u.e_elf.e_scn, s_next, tscn)
805 _libelf_release_scn(scn);
806
807 if (ec == ELFCLASS32) {
808 free(e->e_u.e_elf.e_ehdr.e_ehdr32);
809 if (e->e_u.e_elf.e_phdr.e_phdr32)
810 free(e->e_u.e_elf.e_phdr.e_phdr32);
811
812 e->e_u.e_elf.e_ehdr.e_ehdr32 = NULL;
813 e->e_u.e_elf.e_phdr.e_phdr32 = NULL;
814 } else {
815 free(e->e_u.e_elf.e_ehdr.e_ehdr64);
816 if (e->e_u.e_elf.e_phdr.e_phdr64)
817 free(e->e_u.e_elf.e_phdr.e_phdr64);
818
819 e->e_u.e_elf.e_ehdr.e_ehdr64 = NULL;
820 e->e_u.e_elf.e_phdr.e_phdr64 = NULL;
821 }
822
823 return (rc);
824
825 error:
826 if (newfile)
827 free(newfile);
828 return ((off_t) -1);
829}
830
831off_t
832elf_update(Elf *e, Elf_Cmd c)
833{
834 int ec;
835 off_t rc;
836
837 rc = (off_t) -1;
838
839 if (e == NULL || e->e_kind != ELF_K_ELF ||
840 (c != ELF_C_NULL && c != ELF_C_WRITE)) {
841 LIBELF_SET_ERROR(ARGUMENT, 0);
842 return (rc);
843 }
844
845 if ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64) {
846 LIBELF_SET_ERROR(CLASS, 0);
847 return (rc);
848 }
849
850 if (e->e_version == EV_NONE)
851 e->e_version = EV_CURRENT;
852
853 if (c == ELF_C_WRITE && e->e_cmd == ELF_C_READ) {
854 LIBELF_SET_ERROR(MODE, 0);
855 return (rc);
856 }
857
858 if ((rc = _libelf_resync_elf(e)) < 0)
859 return (rc);
860
861 if (c == ELF_C_NULL)
862 return (rc);
863
864 if (e->e_cmd == ELF_C_READ) {
865 /*
866 * This descriptor was opened in read-only mode or by
867 * elf_memory().
868 */
869 if (e->e_fd)
870 LIBELF_SET_ERROR(MODE, 0);
871 else
872 LIBELF_SET_ERROR(ARGUMENT, 0);
873 return ((off_t) -1);
874 }
875
876 if (e->e_fd < 0) {
877 LIBELF_SET_ERROR(SEQUENCE, 0);
878 return ((off_t) -1);
879 }
880
881 return (_libelf_write_elf(e, rc));
882}
2 * Copyright (c) 2006 Joseph Koshy
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27
28#include <sys/mman.h>
29#include <sys/param.h>
30
31#include <assert.h>
32#include <errno.h>
33#include "gelf.h"
34#include "libelf.h"
35#include <stdlib.h>
36#include <string.h>
37#include <unistd.h>
38
39#include "_libelf.h"
40
41/*
42 * Update the internal data structures associated with an ELF object.
43 * Returns the size in bytes the ELF object would occupy in its file
44 * representation.
45 *
46 * After a successful call to this function, the following structures
47 * are updated:
48 *
49 * - The ELF header is updated.
50 * - All sections are sorted in order of ascending addresses and their
51 * section header table entries updated. An error is signalled
52 * if an overlap was detected among sections.
53 * - All data descriptors associated with a section are sorted in order
54 * of ascending addresses. Overlaps, if detected, are signalled as
55 * errors. Other sanity checks for alignments, section types etc. are
56 * made.
57 *
58 * After a resync_elf() successfully returns, the ELF descriptor is
59 * ready for being handed over to _libelf_write_elf().
60 *
61 * File alignments:
62 * PHDR - Addr
63 * SHDR - Addr
64 *
65 * XXX: how do we handle 'flags'.
66 */
67
68/*
69 * Compute the extents of a section, by looking at the.
70 */
71static int
72_libelf_compute_section_extents(Elf *e, Elf_Scn *s, off_t *rc)
73{
74 int ec;
75 Elf_Data *d, *td;
76 unsigned int elftype;
77 uint32_t sh_type;
78 uint64_t d_align;
79 uint64_t sh_align, sh_entsize, sh_offset, sh_size;
80 uint64_t scn_size, scn_alignment;
81
82 /*
83 * We need to recompute library private data structures if one
84 * or more of the following is true:
85 * - The underlying Shdr structure has been marked `dirty'. Significant
86 * fields include: `sh_offset', `sh_type', `sh_size', `sh_addralign'.
87 * - The Elf_Data structures part of this section have been marked
88 * `dirty'. Affected members include `d_align', `d_offset', `d_type',
89 * and `d_size'.
90 * - The section as a whole is `dirty', e.g., it has been allocated
91 * using elf_newscn(), or if a new Elf_Data structure was added using
92 * elf_newdata().
93 *
94 * Each of these conditions would result in the ELF_F_DIRTY bit being
95 * set on the section descriptor's `s_flags' field.
96 */
97
98 ec = e->e_class;
99
100 if (ec == ELFCLASS32) {
101 sh_type = s->s_shdr.s_shdr32.sh_type;
102 sh_align = (uint64_t) s->s_shdr.s_shdr32.sh_addralign;
103 sh_entsize = (uint64_t) s->s_shdr.s_shdr32.sh_entsize;
104 sh_offset = (uint64_t) s->s_shdr.s_shdr32.sh_offset;
105 sh_size = (uint64_t) s->s_shdr.s_shdr32.sh_size;
106 } else {
107 sh_type = s->s_shdr.s_shdr64.sh_type;
108 sh_align = s->s_shdr.s_shdr64.sh_addralign;
109 sh_entsize = s->s_shdr.s_shdr64.sh_entsize;
110 sh_offset = s->s_shdr.s_shdr64.sh_offset;
111 sh_size = s->s_shdr.s_shdr64.sh_size;
112 }
113
114 if (sh_type == SHT_NULL || sh_type == SHT_NOBITS)
115 return (1);
116
117 if ((s->s_flags & ELF_F_DIRTY) == 0) {
118 if ((size_t) *rc < sh_offset + sh_size)
119 *rc = sh_offset + sh_size;
120 return (1);
121 }
122
123 elftype = _libelf_xlate_shtype(sh_type);
124 if (elftype > ELF_T_LAST) {
125 LIBELF_SET_ERROR(SECTION, 0);
126 return (0);
127 }
128
129 /*
130 * Compute the extent of the data descriptors associated with
131 * this section.
132 */
133 scn_alignment = 0;
134 if (sh_align == 0)
135 sh_align = _libelf_falign(elftype, ec);
136
137 /* Compute the section alignment. */
138 STAILQ_FOREACH(d, &s->s_data, d_next) {
139 if (d->d_type != elftype) {
140 LIBELF_SET_ERROR(DATA, 0);
141 return (0);
142 }
143 if (d->d_version != e->e_version) {
144 LIBELF_SET_ERROR(VERSION, 0);
145 return (0);
146 }
147 if ((d_align = d->d_align) % sh_align) {
148 LIBELF_SET_ERROR(LAYOUT, 0);
149 return (0);
150 }
151 if (d_align == 0 || (d_align & (d_align - 1))) {
152 LIBELF_SET_ERROR(DATA, 0);
153 return (0);
154 }
155 if (d_align > scn_alignment)
156 scn_alignment = d_align;
157 }
158
159 scn_size = 0L;
160
161 STAILQ_FOREACH_SAFE(d, &s->s_data, d_next, td) {
162 if (e->e_flags & ELF_F_LAYOUT) {
163 if ((uint64_t) d->d_off + d->d_size > scn_size)
164 scn_size = d->d_off + d->d_size;
165 } else {
166 scn_size = roundup(scn_size, scn_alignment);
167 d->d_off = scn_size;
168 scn_size += d->d_size;
169 }
170 }
171
172 /*
173 * If the application is requesting full control over the layout
174 * of the section, check its values for sanity.
175 */
176 if (e->e_flags & ELF_F_LAYOUT) {
177 if (scn_alignment > sh_align || sh_offset % sh_align ||
178 sh_size < scn_size) {
179 LIBELF_SET_ERROR(LAYOUT, 0);
180 return (0);
181 }
182 } else {
183 /*
184 * Otherwise compute the values in the section header.
185 */
186
187 if (scn_alignment > sh_align)
188 sh_align = scn_alignment;
189
190 /*
191 * If the section entry size is zero, try and fill in an
192 * appropriate entry size. Per the elf(5) manual page
193 * sections without fixed-size entries should have their
194 * 'sh_entsize' field set to zero.
195 */
196 if (sh_entsize == 0 &&
197 (sh_entsize = _libelf_fsize(elftype, ec, e->e_version,
198 (size_t) 1)) == 1)
199 sh_entsize = 0;
200
201 sh_size = scn_size;
202 sh_offset = roundup(*rc, sh_align);
203
204 if (ec == ELFCLASS32) {
205 s->s_shdr.s_shdr32.sh_addralign = (uint32_t) sh_align;
206 s->s_shdr.s_shdr32.sh_entsize = (uint32_t) sh_entsize;
207 s->s_shdr.s_shdr32.sh_offset = (uint32_t) sh_offset;
208 s->s_shdr.s_shdr32.sh_size = (uint32_t) sh_size;
209 } else {
210 s->s_shdr.s_shdr64.sh_addralign = sh_align;
211 s->s_shdr.s_shdr64.sh_entsize = sh_entsize;
212 s->s_shdr.s_shdr64.sh_offset = sh_offset;
213 s->s_shdr.s_shdr64.sh_size = sh_size;
214 }
215 }
216
217 if ((size_t) *rc < sh_offset + sh_size)
218 *rc = sh_offset + sh_size;
219
220 s->s_size = sh_size;
221 s->s_offset = sh_offset;
222 return (1);
223}
224
225
226/*
227 * Insert a section in ascending order in the list
228 */
229
230static int
231_libelf_insert_section(Elf *e, Elf_Scn *s)
232{
233 Elf_Scn *t, *prevt;
234 uint64_t smax, smin, tmax, tmin;
235
236 smin = s->s_offset;
237 smax = smin + s->s_size;
238
239 prevt = NULL;
240 STAILQ_FOREACH(t, &e->e_u.e_elf.e_scn, s_next) {
241 tmin = t->s_offset;
242 tmax = tmin + t->s_size;
243
244 /* check if there is an overlap */
245 if (tmax < smin) {
246 prevt = t;
247 continue;
248 } else if (smax < tmin)
249 break;
250 else {
251 LIBELF_SET_ERROR(LAYOUT, 0);
252 return (0);
253 }
254 }
255
256 if (prevt)
257 STAILQ_INSERT_AFTER(&e->e_u.e_elf.e_scn, prevt, s, s_next);
258 else
259 STAILQ_INSERT_HEAD(&e->e_u.e_elf.e_scn, s, s_next);
260 return (1);
261}
262
263static off_t
264_libelf_resync_sections(Elf *e, off_t rc)
265{
266 int ec;
267 off_t nrc;
268 size_t sh_type;
269 Elf_Scn *s, *ts;
270
271 ec = e->e_class;
272
273 /*
274 * Make a pass through sections, computing the extent of each
275 * section. Order in increasing order of addresses.
276 */
277
278 nrc = rc;
279 STAILQ_FOREACH(s, &e->e_u.e_elf.e_scn, s_next)
280 if (_libelf_compute_section_extents(e, s, &nrc) == 0)
281 return ((off_t) -1);
282
283 STAILQ_FOREACH_SAFE(s, &e->e_u.e_elf.e_scn, s_next, ts) {
284 if (ec == ELFCLASS32)
285 sh_type = s->s_shdr.s_shdr32.sh_type;
286 else
287 sh_type = s->s_shdr.s_shdr64.sh_type;
288
289 /* XXX Do we need the 'size' field of an SHT_NOBITS section */
290 if (sh_type == SHT_NOBITS || sh_type == SHT_NULL)
291 continue;
292
293 if (s->s_offset < (uint64_t) rc) {
294 if (s->s_offset + s->s_size < (uint64_t) rc) {
295 /*
296 * Try insert this section in the
297 * correct place in the list,
298 * detecting overlaps if any.
299 */
300 STAILQ_REMOVE(&e->e_u.e_elf.e_scn, s, _Elf_Scn,
301 s_next);
302 if (_libelf_insert_section(e, s) == 0)
303 return ((off_t) -1);
304 } else {
305 LIBELF_SET_ERROR(LAYOUT, 0);
306 return ((off_t) -1);
307 }
308 } else
309 rc = s->s_offset + s->s_size;
310 }
311
312 assert(nrc == rc);
313
314 return (rc);
315}
316
317static off_t
318_libelf_resync_elf(Elf *e)
319{
320 int ec, eh_class, eh_type;
321 unsigned int eh_byteorder, eh_version;
322 size_t align, fsz;
323 size_t phnum, shnum;
324 off_t rc, phoff, shoff;
325 void *ehdr;
326 Elf32_Ehdr *eh32;
327 Elf64_Ehdr *eh64;
328
329 rc = 0;
330
331 ec = e->e_class;
332
333 assert(ec == ELFCLASS32 || ec == ELFCLASS64);
334
335 /*
336 * Prepare the EHDR.
337 */
338 if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL)
339 return ((off_t) -1);
340
341 eh32 = ehdr;
342 eh64 = ehdr;
343
344 if (ec == ELFCLASS32) {
345 eh_byteorder = eh32->e_ident[EI_DATA];
346 eh_class = eh32->e_ident[EI_CLASS];
347 phoff = (uint64_t) eh32->e_phoff;
348 shoff = (uint64_t) eh32->e_shoff;
349 eh_type = eh32->e_type;
350 eh_version = eh32->e_version;
351 } else {
352 eh_byteorder = eh64->e_ident[EI_DATA];
353 eh_class = eh64->e_ident[EI_CLASS];
354 phoff = eh64->e_phoff;
355 shoff = eh64->e_shoff;
356 eh_type = eh64->e_type;
357 eh_version = eh64->e_version;
358 }
359
360 if (eh_version == EV_NONE)
361 eh_version = EV_CURRENT;
362
363 if (eh_version != e->e_version) { /* always EV_CURRENT */
364 LIBELF_SET_ERROR(VERSION, 0);
365 return ((off_t) -1);
366 }
367
368 if (eh_class != e->e_class) {
369 LIBELF_SET_ERROR(CLASS, 0);
370 return ((off_t) -1);
371 }
372
373 if (e->e_cmd != ELF_C_WRITE && eh_byteorder != e->e_byteorder) {
374 LIBELF_SET_ERROR(HEADER, 0);
375 return ((off_t) -1);
376 }
377
378 shnum = e->e_u.e_elf.e_nscn;
379 phnum = e->e_u.e_elf.e_nphdr;
380
381 e->e_byteorder = eh_byteorder;
382
383#define INITIALIZE_EHDR(E,EC,V) do { \
384 (E)->e_ident[EI_MAG0] = ELFMAG0; \
385 (E)->e_ident[EI_MAG1] = ELFMAG1; \
386 (E)->e_ident[EI_MAG2] = ELFMAG2; \
387 (E)->e_ident[EI_MAG3] = ELFMAG3; \
388 (E)->e_ident[EI_CLASS] = (EC); \
389 (E)->e_ident[EI_VERSION] = (V); \
390 (E)->e_ehsize = _libelf_fsize(ELF_T_EHDR, (EC), (V), \
391 (size_t) 1); \
392 (E)->e_phentsize = _libelf_fsize(ELF_T_PHDR, (EC), (V), \
393 (size_t) 1); \
394 (E)->e_shentsize = _libelf_fsize(ELF_T_SHDR, (EC), (V), \
395 (size_t) 1); \
396 } while (0)
397
398 if (ec == ELFCLASS32)
399 INITIALIZE_EHDR(eh32, ec, eh_version);
400 else
401 INITIALIZE_EHDR(eh64, ec, eh_version);
402
403 (void) elf_flagehdr(e, ELF_C_SET, ELF_F_DIRTY);
404
405 rc += _libelf_fsize(ELF_T_EHDR, ec, eh_version, (size_t) 1);
406
407 /*
408 * Compute the layout the program header table, if one is
409 * present. The program header table needs to be aligned to a
410 * `natural' boundary.
411 */
412 if (phnum) {
413 fsz = _libelf_fsize(ELF_T_PHDR, ec, eh_version, phnum);
414 align = _libelf_falign(ELF_T_PHDR, ec);
415
416 if (e->e_flags & ELF_F_LAYOUT) {
417 /*
418 * Check offsets for sanity.
419 */
420 if (rc > phoff) {
421 LIBELF_SET_ERROR(HEADER, 0);
422 return ((off_t) -1);
423 }
424
425 if (phoff % align) {
426 LIBELF_SET_ERROR(LAYOUT, 0);
427 return ((off_t) -1);
428 }
429
430 } else
431 phoff = roundup(rc, align);
432
433 rc = phoff + fsz;
434 } else
435 phoff = 0;
436
437 /*
438 * Compute the layout of the sections associated with the
439 * file.
440 */
441
442 if ((rc = _libelf_resync_sections(e, rc)) < 0)
443 return ((off_t) -1);
444
445 /*
446 * Compute the space taken up by the section header table, if
447 * one is needed.
448 */
449 if (shnum) {
450 fsz = _libelf_fsize(ELF_T_SHDR, ec, eh_version, (size_t) 1);
451 align = _libelf_falign(ELF_T_SHDR, ec);
452
453 if (e->e_flags & ELF_F_LAYOUT) {
454 if (rc > shoff) {
455 LIBELF_SET_ERROR(HEADER, 0);
456 return ((off_t) -1);
457 }
458
459 if (shoff % align) {
460 LIBELF_SET_ERROR(LAYOUT, 0);
461 return ((off_t) -1);
462 }
463 } else
464 shoff = roundup(rc, align);
465
466 rc = shoff + fsz * shnum;
467 } else
468 shoff = 0;
469
470 /*
471 * Set the fields of the Executable Header that could potentially use
472 * extended numbering.
473 */
474 _libelf_setphnum(e, ehdr, ec, phnum);
475 _libelf_setshnum(e, ehdr, ec, shnum);
476
477 /*
478 * Update the `e_phoff' and `e_shoff' fields if the library is
479 * doing the layout.
480 */
481 if ((e->e_flags & ELF_F_LAYOUT) == 0) {
482 if (ec == ELFCLASS32) {
483 eh32->e_phoff = (uint32_t) phoff;
484 eh32->e_shoff = (uint32_t) shoff;
485 } else {
486 eh64->e_phoff = (uint64_t) phoff;
487 eh64->e_shoff = (uint64_t) shoff;
488 }
489 }
490
491 return (rc);
492}
493
494/*
495 * Write out the contents of a section.
496 */
497
498static off_t
499_libelf_write_scn(Elf *e, char *nf, Elf_Scn *s, off_t rc)
500{
501 int ec;
502 size_t fsz, msz, nobjects;
503 uint32_t sh_type;
504 uint64_t sh_off;
505 int elftype;
506 Elf_Data *d, dst;
507
508 if ((ec = e->e_class) == ELFCLASS32)
509 sh_type = s->s_shdr.s_shdr32.sh_type;
510 else
511 sh_type = s->s_shdr.s_shdr64.sh_type;
512
513 /*
514 * Ignore sections that do not allocate space in the file.
515 */
516 if (sh_type == SHT_NOBITS || sh_type == SHT_NULL)
517 return (rc);
518
519
520 elftype = _libelf_xlate_shtype(sh_type);
521 assert(elftype >= ELF_T_FIRST && elftype <= ELF_T_LAST);
522
523 msz = _libelf_msize(elftype, ec, e->e_version);
524
525 sh_off = s->s_offset;
526 assert(sh_off % _libelf_falign(elftype, ec) == 0);
527
528 /*
529 * If the section has a `rawdata' descriptor, and the section
530 * contents have not been modified, use its contents directly.
531 * The `s_rawoff' member contains the offset into the original
532 * file, while `s_offset' contains its new location in the
533 * destination.
534 */
535
536 if (STAILQ_EMPTY(&s->s_data)) {
537
538 if ((d = elf_rawdata(s, NULL)) == NULL)
539 return ((off_t) -1);
540
541 STAILQ_FOREACH(d, &s->s_rawdata, d_next) {
542 if ((uint64_t) rc < sh_off + d->d_off)
543 (void) memset(nf + rc,
544 LIBELF_PRIVATE(fillchar), sh_off +
545 d->d_off - rc);
546 rc = sh_off + d->d_off;
547
548 assert(d->d_buf != NULL);
549 assert(d->d_type == ELF_T_BYTE);
550 assert(d->d_version == e->e_version);
551
552 (void) memcpy(nf + rc,
553 e->e_rawfile + s->s_rawoff + d->d_off, d->d_size);
554
555 rc += d->d_size;
556 }
557
558 return (rc);
559 }
560
561 /*
562 * Iterate over the set of data descriptors for this section.
563 * The prior call to _libelf_resync_elf() would have setup the
564 * descriptors for this step.
565 */
566
567 dst.d_version = e->e_version;
568
569 STAILQ_FOREACH(d, &s->s_data, d_next) {
570
571 if ((uint64_t) rc < sh_off + d->d_off)
572 (void) memset(nf + rc,
573 LIBELF_PRIVATE(fillchar), sh_off + d->d_off - rc);
574
575 rc = sh_off + d->d_off;
576
577 assert(d->d_buf != NULL);
578 assert(d->d_type == (Elf_Type) elftype);
579 assert(d->d_version == e->e_version);
580 assert(d->d_size % msz == 0);
581
582 nobjects = d->d_size / msz;
583
584 fsz = _libelf_fsize(elftype, ec, e->e_version, nobjects);
585
586 dst.d_buf = nf + rc;
587 dst.d_size = fsz;
588
589 if (_libelf_xlate(&dst, d, e->e_byteorder, ec, ELF_TOFILE) ==
590 NULL)
591 return ((off_t) -1);
592
593 rc += fsz;
594 }
595
596 return ((off_t) rc);
597}
598
599/*
600 * Write out the file image.
601 *
602 * The original file could have been mapped in with an ELF_C_RDWR
603 * command and the application could have added new content or
604 * re-arranged its sections before calling elf_update(). Consequently
605 * its not safe to work `in place' on the original file. So we
606 * malloc() the required space for the updated ELF object and build
607 * the object there and write it out to the underlying file at the
608 * end. Note that the application may have opened the underlying file
609 * in ELF_C_RDWR and only retrieved/modified a few sections. We take
610 * care to avoid translating file sections unnecessarily.
611 *
612 * Gaps in the coverage of the file by the file's sections will be
613 * filled with the fill character set by elf_fill(3).
614 */
615
616static off_t
617_libelf_write_elf(Elf *e, off_t newsize)
618{
619 int ec;
620 off_t rc;
621 size_t fsz, msz, phnum, shnum;
622 uint64_t phoff, shoff;
623 void *ehdr;
624 char *newfile;
625 Elf_Data dst, src;
626 Elf_Scn *scn, *tscn;
627 Elf32_Ehdr *eh32;
628 Elf64_Ehdr *eh64;
629
630 assert(e->e_kind == ELF_K_ELF);
631 assert(e->e_cmd != ELF_C_READ);
632 assert(e->e_fd >= 0);
633
634 if ((newfile = malloc((size_t) newsize)) == NULL) {
635 LIBELF_SET_ERROR(RESOURCE, errno);
636 return ((off_t) -1);
637 }
638
639 ec = e->e_class;
640
641 ehdr = _libelf_ehdr(e, ec, 0);
642 assert(ehdr != NULL);
643
644 phnum = e->e_u.e_elf.e_nphdr;
645
646 if (ec == ELFCLASS32) {
647 eh32 = (Elf32_Ehdr *) ehdr;
648
649 phoff = (uint64_t) eh32->e_phoff;
650 shnum = eh32->e_shnum;
651 shoff = (uint64_t) eh32->e_shoff;
652 } else {
653 eh64 = (Elf64_Ehdr *) ehdr;
654
655 phoff = eh64->e_phoff;
656 shnum = eh64->e_shnum;
657 shoff = eh64->e_shoff;
658 }
659
660 fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1);
661 msz = _libelf_msize(ELF_T_EHDR, ec, e->e_version);
662
663 (void) memset(&dst, 0, sizeof(dst));
664 (void) memset(&src, 0, sizeof(src));
665
666 src.d_buf = ehdr;
667 src.d_size = msz;
668 src.d_type = ELF_T_EHDR;
669 src.d_version = dst.d_version = e->e_version;
670
671 rc = 0;
672
673 dst.d_buf = newfile + rc;
674 dst.d_size = fsz;
675
676 if (_libelf_xlate(&dst, &src, e->e_byteorder, ec, ELF_TOFILE) ==
677 NULL)
678 goto error;
679
680 rc += fsz;
681
682 /*
683 * Write the program header table if present.
684 */
685
686 if (phnum != 0 && phoff != 0) {
687 assert((unsigned) rc <= phoff);
688
689 fsz = _libelf_fsize(ELF_T_PHDR, ec, e->e_version, phnum);
690
691 assert(phoff % _libelf_falign(ELF_T_PHDR, ec) == 0);
692 assert(fsz > 0);
693
694 src.d_version = dst.d_version = e->e_version;
695 src.d_type = ELF_T_PHDR;
696
697 if (ec == ELFCLASS32)
698 src.d_buf = e->e_u.e_elf.e_phdr.e_phdr32;
699 else
700 src.d_buf = e->e_u.e_elf.e_phdr.e_phdr64;
701
702 src.d_size = phnum * _libelf_msize(ELF_T_PHDR, ec,
703 e->e_version);
704
705 dst.d_size = fsz;
706
707 if ((uint64_t) rc < phoff)
708 (void) memset(newfile + rc,
709 LIBELF_PRIVATE(fillchar), phoff - rc);
710
711 dst.d_buf = newfile + rc;
712
713 if (_libelf_xlate(&dst, &src, e->e_byteorder, ec, ELF_TOFILE) ==
714 NULL)
715 goto error;
716
717 rc = phoff + fsz;
718 }
719
720 /*
721 * Write out individual sections.
722 */
723
724 STAILQ_FOREACH(scn, &e->e_u.e_elf.e_scn, s_next)
725 if ((rc = _libelf_write_scn(e, newfile, scn, rc)) < 0)
726 goto error;
727
728 /*
729 * Write out the section header table, if required.
730 */
731
732 if (shnum != 0 && shoff != 0) {
733 assert((unsigned) rc <= shoff);
734
735 if ((uint64_t) rc < shoff)
736 (void) memset(newfile + rc,
737 LIBELF_PRIVATE(fillchar), shoff - rc);
738
739 rc = shoff;
740
741 assert(rc % _libelf_falign(ELF_T_SHDR, ec) == 0);
742
743 src.d_type = ELF_T_SHDR;
744 src.d_size = _libelf_msize(ELF_T_SHDR, ec, e->e_version);
745 src.d_version = dst.d_version = e->e_version;
746
747 fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, (size_t) 1);
748
749 STAILQ_FOREACH(scn, &e->e_u.e_elf.e_scn, s_next) {
750 if (ec == ELFCLASS32)
751 src.d_buf = &scn->s_shdr.s_shdr32;
752 else
753 src.d_buf = &scn->s_shdr.s_shdr64;
754
755 dst.d_size = fsz;
756 dst.d_buf = newfile + rc;
757
758 if (_libelf_xlate(&dst, &src, e->e_byteorder, ec,
759 ELF_TOFILE) != &dst)
760 goto error;
761
762 rc += fsz;
763 }
764 }
765
766 /*
767 */
768
769 assert(rc == newsize);
770
771 /*
772 * Write out the constructed contents and remap the file in
773 * read-only.
774 */
775
776 if (e->e_rawfile && munmap(e->e_rawfile, e->e_rawsize) < 0) {
777 LIBELF_SET_ERROR(IO, errno);
778 goto error;
779 }
780
781 if (write(e->e_fd, newfile, (size_t) newsize) != newsize ||
782 lseek(e->e_fd, (off_t) 0, SEEK_SET) < 0) {
783 LIBELF_SET_ERROR(IO, errno);
784 goto error;
785 }
786
787 if (e->e_cmd != ELF_C_WRITE) {
788 if ((e->e_rawfile = mmap(NULL, (size_t) newsize, PROT_READ,
789 MAP_PRIVATE, e->e_fd, (off_t) 0)) == MAP_FAILED) {
790 LIBELF_SET_ERROR(IO, errno);
791 goto error;
792 }
793 e->e_rawsize = newsize;
794 }
795
796 /*
797 * Reset flags, remove existing section descriptors and
798 * {E,P}HDR pointers so that a subsequent elf_get{e,p}hdr()
799 * and elf_getscn() will function correctly.
800 */
801
802 e->e_flags &= ~ELF_F_DIRTY;
803
804 STAILQ_FOREACH_SAFE(scn, &e->e_u.e_elf.e_scn, s_next, tscn)
805 _libelf_release_scn(scn);
806
807 if (ec == ELFCLASS32) {
808 free(e->e_u.e_elf.e_ehdr.e_ehdr32);
809 if (e->e_u.e_elf.e_phdr.e_phdr32)
810 free(e->e_u.e_elf.e_phdr.e_phdr32);
811
812 e->e_u.e_elf.e_ehdr.e_ehdr32 = NULL;
813 e->e_u.e_elf.e_phdr.e_phdr32 = NULL;
814 } else {
815 free(e->e_u.e_elf.e_ehdr.e_ehdr64);
816 if (e->e_u.e_elf.e_phdr.e_phdr64)
817 free(e->e_u.e_elf.e_phdr.e_phdr64);
818
819 e->e_u.e_elf.e_ehdr.e_ehdr64 = NULL;
820 e->e_u.e_elf.e_phdr.e_phdr64 = NULL;
821 }
822
823 return (rc);
824
825 error:
826 if (newfile)
827 free(newfile);
828 return ((off_t) -1);
829}
830
831off_t
832elf_update(Elf *e, Elf_Cmd c)
833{
834 int ec;
835 off_t rc;
836
837 rc = (off_t) -1;
838
839 if (e == NULL || e->e_kind != ELF_K_ELF ||
840 (c != ELF_C_NULL && c != ELF_C_WRITE)) {
841 LIBELF_SET_ERROR(ARGUMENT, 0);
842 return (rc);
843 }
844
845 if ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64) {
846 LIBELF_SET_ERROR(CLASS, 0);
847 return (rc);
848 }
849
850 if (e->e_version == EV_NONE)
851 e->e_version = EV_CURRENT;
852
853 if (c == ELF_C_WRITE && e->e_cmd == ELF_C_READ) {
854 LIBELF_SET_ERROR(MODE, 0);
855 return (rc);
856 }
857
858 if ((rc = _libelf_resync_elf(e)) < 0)
859 return (rc);
860
861 if (c == ELF_C_NULL)
862 return (rc);
863
864 if (e->e_cmd == ELF_C_READ) {
865 /*
866 * This descriptor was opened in read-only mode or by
867 * elf_memory().
868 */
869 if (e->e_fd)
870 LIBELF_SET_ERROR(MODE, 0);
871 else
872 LIBELF_SET_ERROR(ARGUMENT, 0);
873 return ((off_t) -1);
874 }
875
876 if (e->e_fd < 0) {
877 LIBELF_SET_ERROR(SEQUENCE, 0);
878 return ((off_t) -1);
879 }
880
881 return (_libelf_write_elf(e, rc));
882}