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}
| 33
34#include <assert.h>
35#include <errno.h>
36#include "gelf.h"
37#include "libelf.h"
38#include <stdlib.h>
39#include <string.h>
40#include <unistd.h>
41
42#include "_libelf.h"
43
44/*
45 * Update the internal data structures associated with an ELF object.
46 * Returns the size in bytes the ELF object would occupy in its file
47 * representation.
48 *
49 * After a successful call to this function, the following structures
50 * are updated:
51 *
52 * - The ELF header is updated.
53 * - All sections are sorted in order of ascending addresses and their
54 * section header table entries updated. An error is signalled
55 * if an overlap was detected among sections.
56 * - All data descriptors associated with a section are sorted in order
57 * of ascending addresses. Overlaps, if detected, are signalled as
58 * errors. Other sanity checks for alignments, section types etc. are
59 * made.
60 *
61 * After a resync_elf() successfully returns, the ELF descriptor is
62 * ready for being handed over to _libelf_write_elf().
63 *
64 * File alignments:
65 * PHDR - Addr
66 * SHDR - Addr
67 *
68 * XXX: how do we handle 'flags'.
69 */
70
71/*
72 * Compute the extents of a section, by looking at the.
73 */
74static int
75_libelf_compute_section_extents(Elf *e, Elf_Scn *s, off_t *rc)
76{
77 int ec;
78 Elf_Data *d, *td;
79 unsigned int elftype;
80 uint32_t sh_type;
81 uint64_t d_align;
82 uint64_t sh_align, sh_entsize, sh_offset, sh_size;
83 uint64_t scn_size, scn_alignment;
84
85 /*
86 * We need to recompute library private data structures if one
87 * or more of the following is true:
88 * - The underlying Shdr structure has been marked `dirty'. Significant
89 * fields include: `sh_offset', `sh_type', `sh_size', `sh_addralign'.
90 * - The Elf_Data structures part of this section have been marked
91 * `dirty'. Affected members include `d_align', `d_offset', `d_type',
92 * and `d_size'.
93 * - The section as a whole is `dirty', e.g., it has been allocated
94 * using elf_newscn(), or if a new Elf_Data structure was added using
95 * elf_newdata().
96 *
97 * Each of these conditions would result in the ELF_F_DIRTY bit being
98 * set on the section descriptor's `s_flags' field.
99 */
100
101 ec = e->e_class;
102
103 if (ec == ELFCLASS32) {
104 sh_type = s->s_shdr.s_shdr32.sh_type;
105 sh_align = (uint64_t) s->s_shdr.s_shdr32.sh_addralign;
106 sh_entsize = (uint64_t) s->s_shdr.s_shdr32.sh_entsize;
107 sh_offset = (uint64_t) s->s_shdr.s_shdr32.sh_offset;
108 sh_size = (uint64_t) s->s_shdr.s_shdr32.sh_size;
109 } else {
110 sh_type = s->s_shdr.s_shdr64.sh_type;
111 sh_align = s->s_shdr.s_shdr64.sh_addralign;
112 sh_entsize = s->s_shdr.s_shdr64.sh_entsize;
113 sh_offset = s->s_shdr.s_shdr64.sh_offset;
114 sh_size = s->s_shdr.s_shdr64.sh_size;
115 }
116
117 if (sh_type == SHT_NULL || sh_type == SHT_NOBITS)
118 return (1);
119
120 if ((s->s_flags & ELF_F_DIRTY) == 0) {
121 if ((size_t) *rc < sh_offset + sh_size)
122 *rc = sh_offset + sh_size;
123 return (1);
124 }
125
126 elftype = _libelf_xlate_shtype(sh_type);
127 if (elftype > ELF_T_LAST) {
128 LIBELF_SET_ERROR(SECTION, 0);
129 return (0);
130 }
131
132 /*
133 * Compute the extent of the data descriptors associated with
134 * this section.
135 */
136 scn_alignment = 0;
137 if (sh_align == 0)
138 sh_align = _libelf_falign(elftype, ec);
139
140 /* Compute the section alignment. */
141 STAILQ_FOREACH(d, &s->s_data, d_next) {
142 if (d->d_type != elftype) {
143 LIBELF_SET_ERROR(DATA, 0);
144 return (0);
145 }
146 if (d->d_version != e->e_version) {
147 LIBELF_SET_ERROR(VERSION, 0);
148 return (0);
149 }
150 if ((d_align = d->d_align) % sh_align) {
151 LIBELF_SET_ERROR(LAYOUT, 0);
152 return (0);
153 }
154 if (d_align == 0 || (d_align & (d_align - 1))) {
155 LIBELF_SET_ERROR(DATA, 0);
156 return (0);
157 }
158 if (d_align > scn_alignment)
159 scn_alignment = d_align;
160 }
161
162 scn_size = 0L;
163
164 STAILQ_FOREACH_SAFE(d, &s->s_data, d_next, td) {
165 if (e->e_flags & ELF_F_LAYOUT) {
166 if ((uint64_t) d->d_off + d->d_size > scn_size)
167 scn_size = d->d_off + d->d_size;
168 } else {
169 scn_size = roundup(scn_size, scn_alignment);
170 d->d_off = scn_size;
171 scn_size += d->d_size;
172 }
173 }
174
175 /*
176 * If the application is requesting full control over the layout
177 * of the section, check its values for sanity.
178 */
179 if (e->e_flags & ELF_F_LAYOUT) {
180 if (scn_alignment > sh_align || sh_offset % sh_align ||
181 sh_size < scn_size) {
182 LIBELF_SET_ERROR(LAYOUT, 0);
183 return (0);
184 }
185 } else {
186 /*
187 * Otherwise compute the values in the section header.
188 */
189
190 if (scn_alignment > sh_align)
191 sh_align = scn_alignment;
192
193 /*
194 * If the section entry size is zero, try and fill in an
195 * appropriate entry size. Per the elf(5) manual page
196 * sections without fixed-size entries should have their
197 * 'sh_entsize' field set to zero.
198 */
199 if (sh_entsize == 0 &&
200 (sh_entsize = _libelf_fsize(elftype, ec, e->e_version,
201 (size_t) 1)) == 1)
202 sh_entsize = 0;
203
204 sh_size = scn_size;
205 sh_offset = roundup(*rc, sh_align);
206
207 if (ec == ELFCLASS32) {
208 s->s_shdr.s_shdr32.sh_addralign = (uint32_t) sh_align;
209 s->s_shdr.s_shdr32.sh_entsize = (uint32_t) sh_entsize;
210 s->s_shdr.s_shdr32.sh_offset = (uint32_t) sh_offset;
211 s->s_shdr.s_shdr32.sh_size = (uint32_t) sh_size;
212 } else {
213 s->s_shdr.s_shdr64.sh_addralign = sh_align;
214 s->s_shdr.s_shdr64.sh_entsize = sh_entsize;
215 s->s_shdr.s_shdr64.sh_offset = sh_offset;
216 s->s_shdr.s_shdr64.sh_size = sh_size;
217 }
218 }
219
220 if ((size_t) *rc < sh_offset + sh_size)
221 *rc = sh_offset + sh_size;
222
223 s->s_size = sh_size;
224 s->s_offset = sh_offset;
225 return (1);
226}
227
228
229/*
230 * Insert a section in ascending order in the list
231 */
232
233static int
234_libelf_insert_section(Elf *e, Elf_Scn *s)
235{
236 Elf_Scn *t, *prevt;
237 uint64_t smax, smin, tmax, tmin;
238
239 smin = s->s_offset;
240 smax = smin + s->s_size;
241
242 prevt = NULL;
243 STAILQ_FOREACH(t, &e->e_u.e_elf.e_scn, s_next) {
244 tmin = t->s_offset;
245 tmax = tmin + t->s_size;
246
247 /* check if there is an overlap */
248 if (tmax < smin) {
249 prevt = t;
250 continue;
251 } else if (smax < tmin)
252 break;
253 else {
254 LIBELF_SET_ERROR(LAYOUT, 0);
255 return (0);
256 }
257 }
258
259 if (prevt)
260 STAILQ_INSERT_AFTER(&e->e_u.e_elf.e_scn, prevt, s, s_next);
261 else
262 STAILQ_INSERT_HEAD(&e->e_u.e_elf.e_scn, s, s_next);
263 return (1);
264}
265
266static off_t
267_libelf_resync_sections(Elf *e, off_t rc)
268{
269 int ec;
270 off_t nrc;
271 size_t sh_type;
272 Elf_Scn *s, *ts;
273
274 ec = e->e_class;
275
276 /*
277 * Make a pass through sections, computing the extent of each
278 * section. Order in increasing order of addresses.
279 */
280
281 nrc = rc;
282 STAILQ_FOREACH(s, &e->e_u.e_elf.e_scn, s_next)
283 if (_libelf_compute_section_extents(e, s, &nrc) == 0)
284 return ((off_t) -1);
285
286 STAILQ_FOREACH_SAFE(s, &e->e_u.e_elf.e_scn, s_next, ts) {
287 if (ec == ELFCLASS32)
288 sh_type = s->s_shdr.s_shdr32.sh_type;
289 else
290 sh_type = s->s_shdr.s_shdr64.sh_type;
291
292 /* XXX Do we need the 'size' field of an SHT_NOBITS section */
293 if (sh_type == SHT_NOBITS || sh_type == SHT_NULL)
294 continue;
295
296 if (s->s_offset < (uint64_t) rc) {
297 if (s->s_offset + s->s_size < (uint64_t) rc) {
298 /*
299 * Try insert this section in the
300 * correct place in the list,
301 * detecting overlaps if any.
302 */
303 STAILQ_REMOVE(&e->e_u.e_elf.e_scn, s, _Elf_Scn,
304 s_next);
305 if (_libelf_insert_section(e, s) == 0)
306 return ((off_t) -1);
307 } else {
308 LIBELF_SET_ERROR(LAYOUT, 0);
309 return ((off_t) -1);
310 }
311 } else
312 rc = s->s_offset + s->s_size;
313 }
314
315 assert(nrc == rc);
316
317 return (rc);
318}
319
320static off_t
321_libelf_resync_elf(Elf *e)
322{
323 int ec, eh_class, eh_type;
324 unsigned int eh_byteorder, eh_version;
325 size_t align, fsz;
326 size_t phnum, shnum;
327 off_t rc, phoff, shoff;
328 void *ehdr;
329 Elf32_Ehdr *eh32;
330 Elf64_Ehdr *eh64;
331
332 rc = 0;
333
334 ec = e->e_class;
335
336 assert(ec == ELFCLASS32 || ec == ELFCLASS64);
337
338 /*
339 * Prepare the EHDR.
340 */
341 if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL)
342 return ((off_t) -1);
343
344 eh32 = ehdr;
345 eh64 = ehdr;
346
347 if (ec == ELFCLASS32) {
348 eh_byteorder = eh32->e_ident[EI_DATA];
349 eh_class = eh32->e_ident[EI_CLASS];
350 phoff = (uint64_t) eh32->e_phoff;
351 shoff = (uint64_t) eh32->e_shoff;
352 eh_type = eh32->e_type;
353 eh_version = eh32->e_version;
354 } else {
355 eh_byteorder = eh64->e_ident[EI_DATA];
356 eh_class = eh64->e_ident[EI_CLASS];
357 phoff = eh64->e_phoff;
358 shoff = eh64->e_shoff;
359 eh_type = eh64->e_type;
360 eh_version = eh64->e_version;
361 }
362
363 if (eh_version == EV_NONE)
364 eh_version = EV_CURRENT;
365
366 if (eh_version != e->e_version) { /* always EV_CURRENT */
367 LIBELF_SET_ERROR(VERSION, 0);
368 return ((off_t) -1);
369 }
370
371 if (eh_class != e->e_class) {
372 LIBELF_SET_ERROR(CLASS, 0);
373 return ((off_t) -1);
374 }
375
376 if (e->e_cmd != ELF_C_WRITE && eh_byteorder != e->e_byteorder) {
377 LIBELF_SET_ERROR(HEADER, 0);
378 return ((off_t) -1);
379 }
380
381 shnum = e->e_u.e_elf.e_nscn;
382 phnum = e->e_u.e_elf.e_nphdr;
383
384 e->e_byteorder = eh_byteorder;
385
386#define INITIALIZE_EHDR(E,EC,V) do { \
387 (E)->e_ident[EI_MAG0] = ELFMAG0; \
388 (E)->e_ident[EI_MAG1] = ELFMAG1; \
389 (E)->e_ident[EI_MAG2] = ELFMAG2; \
390 (E)->e_ident[EI_MAG3] = ELFMAG3; \
391 (E)->e_ident[EI_CLASS] = (EC); \
392 (E)->e_ident[EI_VERSION] = (V); \
393 (E)->e_ehsize = _libelf_fsize(ELF_T_EHDR, (EC), (V), \
394 (size_t) 1); \
395 (E)->e_phentsize = _libelf_fsize(ELF_T_PHDR, (EC), (V), \
396 (size_t) 1); \
397 (E)->e_shentsize = _libelf_fsize(ELF_T_SHDR, (EC), (V), \
398 (size_t) 1); \
399 } while (0)
400
401 if (ec == ELFCLASS32)
402 INITIALIZE_EHDR(eh32, ec, eh_version);
403 else
404 INITIALIZE_EHDR(eh64, ec, eh_version);
405
406 (void) elf_flagehdr(e, ELF_C_SET, ELF_F_DIRTY);
407
408 rc += _libelf_fsize(ELF_T_EHDR, ec, eh_version, (size_t) 1);
409
410 /*
411 * Compute the layout the program header table, if one is
412 * present. The program header table needs to be aligned to a
413 * `natural' boundary.
414 */
415 if (phnum) {
416 fsz = _libelf_fsize(ELF_T_PHDR, ec, eh_version, phnum);
417 align = _libelf_falign(ELF_T_PHDR, ec);
418
419 if (e->e_flags & ELF_F_LAYOUT) {
420 /*
421 * Check offsets for sanity.
422 */
423 if (rc > phoff) {
424 LIBELF_SET_ERROR(HEADER, 0);
425 return ((off_t) -1);
426 }
427
428 if (phoff % align) {
429 LIBELF_SET_ERROR(LAYOUT, 0);
430 return ((off_t) -1);
431 }
432
433 } else
434 phoff = roundup(rc, align);
435
436 rc = phoff + fsz;
437 } else
438 phoff = 0;
439
440 /*
441 * Compute the layout of the sections associated with the
442 * file.
443 */
444
445 if ((rc = _libelf_resync_sections(e, rc)) < 0)
446 return ((off_t) -1);
447
448 /*
449 * Compute the space taken up by the section header table, if
450 * one is needed.
451 */
452 if (shnum) {
453 fsz = _libelf_fsize(ELF_T_SHDR, ec, eh_version, (size_t) 1);
454 align = _libelf_falign(ELF_T_SHDR, ec);
455
456 if (e->e_flags & ELF_F_LAYOUT) {
457 if (rc > shoff) {
458 LIBELF_SET_ERROR(HEADER, 0);
459 return ((off_t) -1);
460 }
461
462 if (shoff % align) {
463 LIBELF_SET_ERROR(LAYOUT, 0);
464 return ((off_t) -1);
465 }
466 } else
467 shoff = roundup(rc, align);
468
469 rc = shoff + fsz * shnum;
470 } else
471 shoff = 0;
472
473 /*
474 * Set the fields of the Executable Header that could potentially use
475 * extended numbering.
476 */
477 _libelf_setphnum(e, ehdr, ec, phnum);
478 _libelf_setshnum(e, ehdr, ec, shnum);
479
480 /*
481 * Update the `e_phoff' and `e_shoff' fields if the library is
482 * doing the layout.
483 */
484 if ((e->e_flags & ELF_F_LAYOUT) == 0) {
485 if (ec == ELFCLASS32) {
486 eh32->e_phoff = (uint32_t) phoff;
487 eh32->e_shoff = (uint32_t) shoff;
488 } else {
489 eh64->e_phoff = (uint64_t) phoff;
490 eh64->e_shoff = (uint64_t) shoff;
491 }
492 }
493
494 return (rc);
495}
496
497/*
498 * Write out the contents of a section.
499 */
500
501static off_t
502_libelf_write_scn(Elf *e, char *nf, Elf_Scn *s, off_t rc)
503{
504 int ec;
505 size_t fsz, msz, nobjects;
506 uint32_t sh_type;
507 uint64_t sh_off;
508 int elftype;
509 Elf_Data *d, dst;
510
511 if ((ec = e->e_class) == ELFCLASS32)
512 sh_type = s->s_shdr.s_shdr32.sh_type;
513 else
514 sh_type = s->s_shdr.s_shdr64.sh_type;
515
516 /*
517 * Ignore sections that do not allocate space in the file.
518 */
519 if (sh_type == SHT_NOBITS || sh_type == SHT_NULL)
520 return (rc);
521
522
523 elftype = _libelf_xlate_shtype(sh_type);
524 assert(elftype >= ELF_T_FIRST && elftype <= ELF_T_LAST);
525
526 msz = _libelf_msize(elftype, ec, e->e_version);
527
528 sh_off = s->s_offset;
529 assert(sh_off % _libelf_falign(elftype, ec) == 0);
530
531 /*
532 * If the section has a `rawdata' descriptor, and the section
533 * contents have not been modified, use its contents directly.
534 * The `s_rawoff' member contains the offset into the original
535 * file, while `s_offset' contains its new location in the
536 * destination.
537 */
538
539 if (STAILQ_EMPTY(&s->s_data)) {
540
541 if ((d = elf_rawdata(s, NULL)) == NULL)
542 return ((off_t) -1);
543
544 STAILQ_FOREACH(d, &s->s_rawdata, d_next) {
545 if ((uint64_t) rc < sh_off + d->d_off)
546 (void) memset(nf + rc,
547 LIBELF_PRIVATE(fillchar), sh_off +
548 d->d_off - rc);
549 rc = sh_off + d->d_off;
550
551 assert(d->d_buf != NULL);
552 assert(d->d_type == ELF_T_BYTE);
553 assert(d->d_version == e->e_version);
554
555 (void) memcpy(nf + rc,
556 e->e_rawfile + s->s_rawoff + d->d_off, d->d_size);
557
558 rc += d->d_size;
559 }
560
561 return (rc);
562 }
563
564 /*
565 * Iterate over the set of data descriptors for this section.
566 * The prior call to _libelf_resync_elf() would have setup the
567 * descriptors for this step.
568 */
569
570 dst.d_version = e->e_version;
571
572 STAILQ_FOREACH(d, &s->s_data, d_next) {
573
574 if ((uint64_t) rc < sh_off + d->d_off)
575 (void) memset(nf + rc,
576 LIBELF_PRIVATE(fillchar), sh_off + d->d_off - rc);
577
578 rc = sh_off + d->d_off;
579
580 assert(d->d_buf != NULL);
581 assert(d->d_type == (Elf_Type) elftype);
582 assert(d->d_version == e->e_version);
583 assert(d->d_size % msz == 0);
584
585 nobjects = d->d_size / msz;
586
587 fsz = _libelf_fsize(elftype, ec, e->e_version, nobjects);
588
589 dst.d_buf = nf + rc;
590 dst.d_size = fsz;
591
592 if (_libelf_xlate(&dst, d, e->e_byteorder, ec, ELF_TOFILE) ==
593 NULL)
594 return ((off_t) -1);
595
596 rc += fsz;
597 }
598
599 return ((off_t) rc);
600}
601
602/*
603 * Write out the file image.
604 *
605 * The original file could have been mapped in with an ELF_C_RDWR
606 * command and the application could have added new content or
607 * re-arranged its sections before calling elf_update(). Consequently
608 * its not safe to work `in place' on the original file. So we
609 * malloc() the required space for the updated ELF object and build
610 * the object there and write it out to the underlying file at the
611 * end. Note that the application may have opened the underlying file
612 * in ELF_C_RDWR and only retrieved/modified a few sections. We take
613 * care to avoid translating file sections unnecessarily.
614 *
615 * Gaps in the coverage of the file by the file's sections will be
616 * filled with the fill character set by elf_fill(3).
617 */
618
619static off_t
620_libelf_write_elf(Elf *e, off_t newsize)
621{
622 int ec;
623 off_t rc;
624 size_t fsz, msz, phnum, shnum;
625 uint64_t phoff, shoff;
626 void *ehdr;
627 char *newfile;
628 Elf_Data dst, src;
629 Elf_Scn *scn, *tscn;
630 Elf32_Ehdr *eh32;
631 Elf64_Ehdr *eh64;
632
633 assert(e->e_kind == ELF_K_ELF);
634 assert(e->e_cmd != ELF_C_READ);
635 assert(e->e_fd >= 0);
636
637 if ((newfile = malloc((size_t) newsize)) == NULL) {
638 LIBELF_SET_ERROR(RESOURCE, errno);
639 return ((off_t) -1);
640 }
641
642 ec = e->e_class;
643
644 ehdr = _libelf_ehdr(e, ec, 0);
645 assert(ehdr != NULL);
646
647 phnum = e->e_u.e_elf.e_nphdr;
648
649 if (ec == ELFCLASS32) {
650 eh32 = (Elf32_Ehdr *) ehdr;
651
652 phoff = (uint64_t) eh32->e_phoff;
653 shnum = eh32->e_shnum;
654 shoff = (uint64_t) eh32->e_shoff;
655 } else {
656 eh64 = (Elf64_Ehdr *) ehdr;
657
658 phoff = eh64->e_phoff;
659 shnum = eh64->e_shnum;
660 shoff = eh64->e_shoff;
661 }
662
663 fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1);
664 msz = _libelf_msize(ELF_T_EHDR, ec, e->e_version);
665
666 (void) memset(&dst, 0, sizeof(dst));
667 (void) memset(&src, 0, sizeof(src));
668
669 src.d_buf = ehdr;
670 src.d_size = msz;
671 src.d_type = ELF_T_EHDR;
672 src.d_version = dst.d_version = e->e_version;
673
674 rc = 0;
675
676 dst.d_buf = newfile + rc;
677 dst.d_size = fsz;
678
679 if (_libelf_xlate(&dst, &src, e->e_byteorder, ec, ELF_TOFILE) ==
680 NULL)
681 goto error;
682
683 rc += fsz;
684
685 /*
686 * Write the program header table if present.
687 */
688
689 if (phnum != 0 && phoff != 0) {
690 assert((unsigned) rc <= phoff);
691
692 fsz = _libelf_fsize(ELF_T_PHDR, ec, e->e_version, phnum);
693
694 assert(phoff % _libelf_falign(ELF_T_PHDR, ec) == 0);
695 assert(fsz > 0);
696
697 src.d_version = dst.d_version = e->e_version;
698 src.d_type = ELF_T_PHDR;
699
700 if (ec == ELFCLASS32)
701 src.d_buf = e->e_u.e_elf.e_phdr.e_phdr32;
702 else
703 src.d_buf = e->e_u.e_elf.e_phdr.e_phdr64;
704
705 src.d_size = phnum * _libelf_msize(ELF_T_PHDR, ec,
706 e->e_version);
707
708 dst.d_size = fsz;
709
710 if ((uint64_t) rc < phoff)
711 (void) memset(newfile + rc,
712 LIBELF_PRIVATE(fillchar), phoff - rc);
713
714 dst.d_buf = newfile + rc;
715
716 if (_libelf_xlate(&dst, &src, e->e_byteorder, ec, ELF_TOFILE) ==
717 NULL)
718 goto error;
719
720 rc = phoff + fsz;
721 }
722
723 /*
724 * Write out individual sections.
725 */
726
727 STAILQ_FOREACH(scn, &e->e_u.e_elf.e_scn, s_next)
728 if ((rc = _libelf_write_scn(e, newfile, scn, rc)) < 0)
729 goto error;
730
731 /*
732 * Write out the section header table, if required.
733 */
734
735 if (shnum != 0 && shoff != 0) {
736 assert((unsigned) rc <= shoff);
737
738 if ((uint64_t) rc < shoff)
739 (void) memset(newfile + rc,
740 LIBELF_PRIVATE(fillchar), shoff - rc);
741
742 rc = shoff;
743
744 assert(rc % _libelf_falign(ELF_T_SHDR, ec) == 0);
745
746 src.d_type = ELF_T_SHDR;
747 src.d_size = _libelf_msize(ELF_T_SHDR, ec, e->e_version);
748 src.d_version = dst.d_version = e->e_version;
749
750 fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, (size_t) 1);
751
752 STAILQ_FOREACH(scn, &e->e_u.e_elf.e_scn, s_next) {
753 if (ec == ELFCLASS32)
754 src.d_buf = &scn->s_shdr.s_shdr32;
755 else
756 src.d_buf = &scn->s_shdr.s_shdr64;
757
758 dst.d_size = fsz;
759 dst.d_buf = newfile + rc;
760
761 if (_libelf_xlate(&dst, &src, e->e_byteorder, ec,
762 ELF_TOFILE) != &dst)
763 goto error;
764
765 rc += fsz;
766 }
767 }
768
769 /*
770 */
771
772 assert(rc == newsize);
773
774 /*
775 * Write out the constructed contents and remap the file in
776 * read-only.
777 */
778
779 if (e->e_rawfile && munmap(e->e_rawfile, e->e_rawsize) < 0) {
780 LIBELF_SET_ERROR(IO, errno);
781 goto error;
782 }
783
784 if (write(e->e_fd, newfile, (size_t) newsize) != newsize ||
785 lseek(e->e_fd, (off_t) 0, SEEK_SET) < 0) {
786 LIBELF_SET_ERROR(IO, errno);
787 goto error;
788 }
789
790 if (e->e_cmd != ELF_C_WRITE) {
791 if ((e->e_rawfile = mmap(NULL, (size_t) newsize, PROT_READ,
792 MAP_PRIVATE, e->e_fd, (off_t) 0)) == MAP_FAILED) {
793 LIBELF_SET_ERROR(IO, errno);
794 goto error;
795 }
796 e->e_rawsize = newsize;
797 }
798
799 /*
800 * Reset flags, remove existing section descriptors and
801 * {E,P}HDR pointers so that a subsequent elf_get{e,p}hdr()
802 * and elf_getscn() will function correctly.
803 */
804
805 e->e_flags &= ~ELF_F_DIRTY;
806
807 STAILQ_FOREACH_SAFE(scn, &e->e_u.e_elf.e_scn, s_next, tscn)
808 _libelf_release_scn(scn);
809
810 if (ec == ELFCLASS32) {
811 free(e->e_u.e_elf.e_ehdr.e_ehdr32);
812 if (e->e_u.e_elf.e_phdr.e_phdr32)
813 free(e->e_u.e_elf.e_phdr.e_phdr32);
814
815 e->e_u.e_elf.e_ehdr.e_ehdr32 = NULL;
816 e->e_u.e_elf.e_phdr.e_phdr32 = NULL;
817 } else {
818 free(e->e_u.e_elf.e_ehdr.e_ehdr64);
819 if (e->e_u.e_elf.e_phdr.e_phdr64)
820 free(e->e_u.e_elf.e_phdr.e_phdr64);
821
822 e->e_u.e_elf.e_ehdr.e_ehdr64 = NULL;
823 e->e_u.e_elf.e_phdr.e_phdr64 = NULL;
824 }
825
826 return (rc);
827
828 error:
829 if (newfile)
830 free(newfile);
831 return ((off_t) -1);
832}
833
834off_t
835elf_update(Elf *e, Elf_Cmd c)
836{
837 int ec;
838 off_t rc;
839
840 rc = (off_t) -1;
841
842 if (e == NULL || e->e_kind != ELF_K_ELF ||
843 (c != ELF_C_NULL && c != ELF_C_WRITE)) {
844 LIBELF_SET_ERROR(ARGUMENT, 0);
845 return (rc);
846 }
847
848 if ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64) {
849 LIBELF_SET_ERROR(CLASS, 0);
850 return (rc);
851 }
852
853 if (e->e_version == EV_NONE)
854 e->e_version = EV_CURRENT;
855
856 if (c == ELF_C_WRITE && e->e_cmd == ELF_C_READ) {
857 LIBELF_SET_ERROR(MODE, 0);
858 return (rc);
859 }
860
861 if ((rc = _libelf_resync_elf(e)) < 0)
862 return (rc);
863
864 if (c == ELF_C_NULL)
865 return (rc);
866
867 if (e->e_cmd == ELF_C_READ) {
868 /*
869 * This descriptor was opened in read-only mode or by
870 * elf_memory().
871 */
872 if (e->e_fd)
873 LIBELF_SET_ERROR(MODE, 0);
874 else
875 LIBELF_SET_ERROR(ARGUMENT, 0);
876 return ((off_t) -1);
877 }
878
879 if (e->e_fd < 0) {
880 LIBELF_SET_ERROR(SEQUENCE, 0);
881 return ((off_t) -1);
882 }
883
884 return (_libelf_write_elf(e, rc));
885}
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