1/*-
2 * SPDX-License-Identifier: BSD-4-Clause
3 *
4 * Copyright (c) 2000, Boris Popov
5 * Copyright (c) 1998-2000 Doug Rabson
6 * Copyright (c) 2004 Peter Wemm
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 * 3. All advertising materials mentioning features or use of this software
18 *    must display the following acknowledgement:
19 *    This product includes software developed by Boris Popov.
20 * 4. Neither the name of the author nor the names of any co-contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37#include <sys/param.h>
38
39#include <err.h>
40#include <errno.h>
41#include <gelf.h>
42#include <stdio.h>
43#include <stdlib.h>
44#include <string.h>
45
46#include "ef.h"
47
48typedef struct {
49	GElf_Addr	addr;
50	GElf_Off	offset;
51	GElf_Off	size;
52	int		flags;
53	int		sec;	/* Original section */
54	char		*name;
55} Elf_progent;
56
57typedef struct {
58	GElf_Rel	*rel;
59	long		nrel;
60	int		sec;
61} Elf_relent;
62
63typedef struct {
64	GElf_Rela	*rela;
65	long		nrela;
66	int		sec;
67} Elf_relaent;
68
69struct ef_file {
70	char		*ef_name;
71	struct elf_file *ef_efile;
72
73	Elf_progent	*progtab;
74	int		nprogtab;
75
76	Elf_relaent	*relatab;
77	int		nrela;
78
79	Elf_relent	*reltab;
80	int		nrel;
81
82	GElf_Sym	*ddbsymtab;	/* The symbol table we are using */
83	size_t		ddbsymcnt;	/* Number of symbols */
84	caddr_t		ddbstrtab;	/* String table */
85	long		ddbstrcnt;	/* number of bytes in string table */
86
87	caddr_t		shstrtab;	/* Section name string table */
88	long		shstrcnt;	/* number of bytes in string table */
89
90	int		ef_verbose;
91};
92
93static void	ef_obj_close(elf_file_t ef);
94
95static int	ef_obj_seg_read_rel(elf_file_t ef, GElf_Addr address,
96		    size_t len, void *dest);
97static int	ef_obj_seg_read_string(elf_file_t ef, GElf_Addr address,
98		    size_t len, char *dest);
99
100static GElf_Addr ef_obj_symaddr(elf_file_t ef, GElf_Size symidx);
101static int	ef_obj_lookup_set(elf_file_t ef, const char *name,
102		    GElf_Addr *startp, GElf_Addr *stopp, long *countp);
103static int	ef_obj_lookup_symbol(elf_file_t ef, const char *name,
104		    GElf_Sym **sym);
105
106static struct elf_file_ops ef_obj_file_ops = {
107	.close			= ef_obj_close,
108	.seg_read_rel		= ef_obj_seg_read_rel,
109	.seg_read_string	= ef_obj_seg_read_string,
110	.symaddr		= ef_obj_symaddr,
111	.lookup_set		= ef_obj_lookup_set,
112};
113
114static GElf_Off
115ef_obj_get_offset(elf_file_t ef, GElf_Addr addr)
116{
117	Elf_progent *pt;
118	int i;
119
120	for (i = 0; i < ef->nprogtab; i++) {
121		pt = &ef->progtab[i];
122		if (pt->offset == (GElf_Off)-1)
123			continue;
124		if (addr >= pt->addr && addr < pt->addr + pt->size)
125			return (pt->offset + (addr - pt->addr));
126	}
127	return (0);
128}
129
130static int
131ef_obj_lookup_symbol(elf_file_t ef, const char *name, GElf_Sym **sym)
132{
133	GElf_Sym *symp;
134	const char *strp;
135	int i;
136
137	for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
138		strp = ef->ddbstrtab + symp->st_name;
139		if (symp->st_shndx != SHN_UNDEF && strcmp(name, strp) == 0) {
140			*sym = symp;
141			return (0);
142		}
143	}
144	return (ENOENT);
145}
146
147static int
148ef_obj_lookup_set(elf_file_t ef, const char *name, GElf_Addr *startp,
149    GElf_Addr *stopp, long *countp)
150{
151	int i;
152
153	for (i = 0; i < ef->nprogtab; i++) {
154		if ((strncmp(ef->progtab[i].name, "set_", 4) == 0) &&
155		    strcmp(ef->progtab[i].name + 4, name) == 0) {
156			*startp = ef->progtab[i].addr;
157			*stopp = ef->progtab[i].addr + ef->progtab[i].size;
158			*countp = (*stopp - *startp) /
159			    elf_pointer_size(ef->ef_efile);
160			return (0);
161		}
162	}
163	return (ESRCH);
164}
165
166static GElf_Addr
167ef_obj_symaddr(elf_file_t ef, GElf_Size symidx)
168{
169	const GElf_Sym *sym;
170
171	if (symidx >= ef->ddbsymcnt)
172		return (0);
173	sym = ef->ddbsymtab + symidx;
174
175	if (sym->st_shndx != SHN_UNDEF)
176		return (sym->st_value);
177	return (0);
178}
179
180static int
181ef_obj_seg_read_rel(elf_file_t ef, GElf_Addr address, size_t len, void *dest)
182{
183	GElf_Off secofs;
184	GElf_Rel *r;
185	GElf_Rela *a;
186	GElf_Addr secbase, dataoff;
187	int error, i, sec;
188
189	/* Find out which section contains the data. */
190	sec = -1;
191	for (i = 0; i < ef->nprogtab; i++) {
192		if (address < ef->progtab[i].addr)
193			continue;
194
195		dataoff = address - ef->progtab[i].addr;
196		if (dataoff + len > ef->progtab[i].size)
197			continue;
198
199		sec = ef->progtab[i].sec;
200		secbase = ef->progtab[i].addr;
201		secofs = ef->progtab[i].offset;
202		break;
203	}
204
205	if (sec == -1) {
206		if (ef->ef_verbose)
207			warnx("ef_obj_seg_read_rel(%s): bad address (%jx)",
208			    ef->ef_name, (uintmax_t)address);
209		return (EFAULT);
210	}
211
212	if (secofs == (GElf_Off)-1) {
213		memset(dest, 0, len);
214	} else {
215		error = elf_read_raw_data(ef->ef_efile, secofs + dataoff, dest,
216		    len);
217		if (error != 0)
218			return (error);
219	}
220
221	/* Now do the relocations. */
222	for (i = 0; i < ef->nrel; i++) {
223		if (ef->reltab[i].sec != sec)
224			continue;
225		for (r = ef->reltab[i].rel;
226		     r < &ef->reltab[i].rel[ef->reltab[i].nrel]; r++) {
227			error = elf_reloc(ef->ef_efile, r, ELF_T_REL, secbase,
228			    address, len, dest);
229			if (error != 0)
230				return (error);
231		}
232	}
233	for (i = 0; i < ef->nrela; i++) {
234		if (ef->relatab[i].sec != sec)
235			continue;
236		for (a = ef->relatab[i].rela;
237		     a < &ef->relatab[i].rela[ef->relatab[i].nrela]; a++) {
238			error = elf_reloc(ef->ef_efile, a, ELF_T_RELA, secbase,
239			    address, len, dest);
240			if (error != 0)
241				return (error);
242		}
243	}
244	return (0);
245}
246
247static int
248ef_obj_seg_read_string(elf_file_t ef, GElf_Addr address, size_t len, char *dest)
249{
250	GElf_Off ofs;
251
252	ofs = ef_obj_get_offset(ef, address);
253	if (ofs == 0) {
254		if (ef->ef_verbose)
255			warnx("ef_obj_seg_read_string(%s): bad address (%jx)",
256			    ef->ef_name, (uintmax_t)address);
257		return (EFAULT);
258	}
259
260	return (elf_read_raw_string(ef->ef_efile, ofs, dest, len));
261}
262
263int
264ef_obj_open(struct elf_file *efile, int verbose)
265{
266	elf_file_t ef;
267	GElf_Ehdr *hdr;
268	GElf_Shdr *shdr;
269	GElf_Sym *es;
270	GElf_Addr mapbase;
271	size_t i, nshdr;
272	int error, pb, ra, rl;
273	int j, nsym, symstrindex, symtabindex;
274
275	hdr = &efile->ef_hdr;
276	if (hdr->e_type != ET_REL || hdr->e_shnum == 0 || hdr->e_shoff == 0 ||
277	    hdr->e_shentsize != elf_object_size(efile, ELF_T_SHDR))
278		return (EFTYPE);
279
280	ef = calloc(1, sizeof(*ef));
281	if (ef == NULL)
282		return (errno);
283
284	efile->ef_ef = ef;
285	efile->ef_ops = &ef_obj_file_ops;
286
287	ef->ef_verbose = verbose;
288	ef->ef_name = strdup(efile->ef_filename);
289	ef->ef_efile = efile;
290
291	error = elf_read_shdrs(efile, &nshdr, &shdr);
292	if (error != 0) {
293		shdr = NULL;
294		goto out;
295	}
296
297	/* Scan the section headers for information and table sizing. */
298	nsym = 0;
299	symtabindex = -1;
300	symstrindex = -1;
301	for (i = 0; i < nshdr; i++) {
302		switch (shdr[i].sh_type) {
303		case SHT_PROGBITS:
304		case SHT_NOBITS:
305			ef->nprogtab++;
306			break;
307		case SHT_SYMTAB:
308			nsym++;
309			symtabindex = i;
310			symstrindex = shdr[i].sh_link;
311			break;
312		case SHT_REL:
313			ef->nrel++;
314			break;
315		case SHT_RELA:
316			ef->nrela++;
317			break;
318		case SHT_STRTAB:
319			break;
320		}
321	}
322
323	if (ef->nprogtab == 0) {
324		warnx("%s: file has no contents", ef->ef_name);
325		goto out;
326	}
327	if (nsym != 1) {
328		warnx("%s: file has no valid symbol table", ef->ef_name);
329		goto out;
330	}
331	if (symstrindex < 0 || symstrindex > nshdr ||
332	    shdr[symstrindex].sh_type != SHT_STRTAB) {
333		warnx("%s: file has invalid symbol strings", ef->ef_name);
334		goto out;
335	}
336
337	/* Allocate space for tracking the load chunks */
338	if (ef->nprogtab != 0)
339		ef->progtab = calloc(ef->nprogtab, sizeof(*ef->progtab));
340	if (ef->nrel != 0)
341		ef->reltab = calloc(ef->nrel, sizeof(*ef->reltab));
342	if (ef->nrela != 0)
343		ef->relatab = calloc(ef->nrela, sizeof(*ef->relatab));
344	if ((ef->nprogtab != 0 && ef->progtab == NULL) ||
345	    (ef->nrel != 0 && ef->reltab == NULL) ||
346	    (ef->nrela != 0 && ef->relatab == NULL)) {
347		printf("malloc failed\n");
348		error = ENOMEM;
349		goto out;
350	}
351
352	if (elf_read_symbols(efile, symtabindex, &ef->ddbsymcnt,
353	    &ef->ddbsymtab) != 0) {
354		printf("elf_read_symbols failed\n");
355		goto out;
356	}
357
358	if (elf_read_string_table(efile, &shdr[symstrindex], &ef->ddbstrcnt,
359	    &ef->ddbstrtab) != 0) {
360		printf("elf_read_string_table failed\n");
361		goto out;
362	}
363
364	/* Do we have a string table for the section names?  */
365	if (hdr->e_shstrndx != 0 &&
366	    shdr[hdr->e_shstrndx].sh_type == SHT_STRTAB) {
367		if (elf_read_string_table(efile, &shdr[hdr->e_shstrndx],
368		    &ef->shstrcnt, &ef->shstrtab) != 0) {
369			printf("elf_read_string_table failed\n");
370			goto out;
371		}
372	}
373
374	/*
375	 * Now allocate address space for code/data(progbits) and
376	 * bss(nobits) and allocate space for and load relocs.
377	 */
378	pb = 0;
379	rl = 0;
380	ra = 0;
381	mapbase = 0;
382	for (i = 0; i < nshdr; i++) {
383		switch (shdr[i].sh_type) {
384		case SHT_PROGBITS:
385		case SHT_NOBITS:
386			mapbase = roundup2(mapbase, shdr[i].sh_addralign);
387			ef->progtab[pb].addr = mapbase;
388			if (shdr[i].sh_type == SHT_PROGBITS) {
389				ef->progtab[pb].name = "<<PROGBITS>>";
390				ef->progtab[pb].offset = shdr[i].sh_offset;
391			} else {
392				ef->progtab[pb].name = "<<NOBITS>>";
393				ef->progtab[pb].offset = (GElf_Off)-1;
394			}
395			ef->progtab[pb].size = shdr[i].sh_size;
396			ef->progtab[pb].sec = i;
397			if (ef->shstrtab && shdr[i].sh_name != 0)
398				ef->progtab[pb].name =
399				    ef->shstrtab + shdr[i].sh_name;
400
401			/* Update all symbol values with the offset. */
402			for (j = 0; j < ef->ddbsymcnt; j++) {
403				es = &ef->ddbsymtab[j];
404				if (es->st_shndx != i)
405					continue;
406				es->st_value += ef->progtab[pb].addr;
407			}
408			mapbase += shdr[i].sh_size;
409			pb++;
410			break;
411		case SHT_REL:
412			ef->reltab[rl].sec = shdr[i].sh_info;
413			if (elf_read_rel(efile, i, &ef->reltab[rl].nrel,
414			    &ef->reltab[rl].rel) != 0) {
415				printf("elf_read_rel failed\n");
416				goto out;
417			}
418			rl++;
419			break;
420		case SHT_RELA:
421			ef->relatab[ra].sec = shdr[i].sh_info;
422			if (elf_read_rela(efile, i, &ef->relatab[ra].nrela,
423			    &ef->relatab[ra].rela) != 0) {
424				printf("elf_read_rela failed\n");
425				goto out;
426			}
427			ra++;
428			break;
429		}
430	}
431	error = 0;
432out:
433	free(shdr);
434	if (error != 0)
435		ef_obj_close(ef);
436	return (error);
437}
438
439static void
440ef_obj_close(elf_file_t ef)
441{
442	int i;
443
444	if (ef->ef_name)
445		free(ef->ef_name);
446	if (ef->nprogtab != 0)
447		free(ef->progtab);
448	if (ef->nrel != 0) {
449		for (i = 0; i < ef->nrel; i++)
450			if (ef->reltab[i].rel != NULL)
451				free(ef->reltab[i].rel);
452		free(ef->reltab);
453	}
454	if (ef->nrela != 0) {
455		for (i = 0; i < ef->nrela; i++)
456			if (ef->relatab[i].rela != NULL)
457				free(ef->relatab[i].rela);
458		free(ef->relatab);
459	}
460	if (ef->ddbsymtab != NULL)
461		free(ef->ddbsymtab);
462	if (ef->ddbstrtab != NULL)
463		free(ef->ddbstrtab);
464	if (ef->shstrtab != NULL)
465		free(ef->shstrtab);
466	ef->ef_efile->ef_ops = NULL;
467	ef->ef_efile->ef_ef = NULL;
468	free(ef);
469}
470