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 "kldelf.h"
47
48 typedef 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
57 typedef struct {
58 GElf_Rel *rel;
59 long nrel;
60 int sec;
61 } Elf_relent;
62
63 typedef struct {
64 GElf_Rela *rela;
65 long nrela;
66 int sec;
67 } Elf_relaent;
68
69 struct 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
93 static void ef_obj_close(elf_file_t ef);
94
95 static int ef_obj_seg_read_rel(elf_file_t ef, GElf_Addr address,
96 size_t len, void *dest);
97 static int ef_obj_seg_read_string(elf_file_t ef, GElf_Addr address,
98 size_t len, char *dest);
99
100 static GElf_Addr ef_obj_symaddr(elf_file_t ef, GElf_Size symidx);
101 static int ef_obj_lookup_set(elf_file_t ef, const char *name,
102 GElf_Addr *startp, GElf_Addr *stopp, long *countp);
103 static int ef_obj_lookup_symbol(elf_file_t ef, const char *name,
104 GElf_Sym **sym, bool see_local);
105
106 static 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 .lookup_symbol = ef_obj_lookup_symbol,
113 };
114
115 static GElf_Off
ef_obj_get_offset(elf_file_t ef,GElf_Addr addr)116 ef_obj_get_offset(elf_file_t ef, GElf_Addr addr)
117 {
118 Elf_progent *pt;
119 int i;
120
121 for (i = 0; i < ef->nprogtab; i++) {
122 pt = &ef->progtab[i];
123 if (pt->offset == (GElf_Off)-1)
124 continue;
125 if (addr >= pt->addr && addr < pt->addr + pt->size)
126 return (pt->offset + (addr - pt->addr));
127 }
128 return (0);
129 }
130
131 static int
ef_obj_lookup_symbol(elf_file_t ef,const char * name,GElf_Sym ** sym,bool see_local)132 ef_obj_lookup_symbol(elf_file_t ef, const char *name, GElf_Sym **sym,
133 bool see_local)
134 {
135 GElf_Sym *symp;
136 const char *strp;
137 int i;
138
139 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
140 strp = ef->ddbstrtab + symp->st_name;
141 if (symp->st_shndx != SHN_UNDEF && strcmp(name, strp) == 0) {
142 if (see_local ||
143 GELF_ST_BIND(symp->st_info) != STB_LOCAL) {
144 *sym = symp;
145 return (0);
146 }
147 }
148 }
149 return (ENOENT);
150 }
151
152 static int
ef_obj_lookup_set(elf_file_t ef,const char * name,GElf_Addr * startp,GElf_Addr * stopp,long * countp)153 ef_obj_lookup_set(elf_file_t ef, const char *name, GElf_Addr *startp,
154 GElf_Addr *stopp, long *countp)
155 {
156 int i;
157
158 for (i = 0; i < ef->nprogtab; i++) {
159 if ((strncmp(ef->progtab[i].name, "set_", 4) == 0) &&
160 strcmp(ef->progtab[i].name + 4, name) == 0) {
161 *startp = ef->progtab[i].addr;
162 *stopp = ef->progtab[i].addr + ef->progtab[i].size;
163 *countp = (*stopp - *startp) /
164 elf_pointer_size(ef->ef_efile);
165 return (0);
166 }
167 }
168 return (ESRCH);
169 }
170
171 static GElf_Addr
ef_obj_symaddr(elf_file_t ef,GElf_Size symidx)172 ef_obj_symaddr(elf_file_t ef, GElf_Size symidx)
173 {
174 const GElf_Sym *sym;
175
176 if (symidx >= ef->ddbsymcnt)
177 return (0);
178 sym = ef->ddbsymtab + symidx;
179
180 if (sym->st_shndx != SHN_UNDEF)
181 return (sym->st_value);
182 return (0);
183 }
184
185 static int
ef_obj_seg_read_rel(elf_file_t ef,GElf_Addr address,size_t len,void * dest)186 ef_obj_seg_read_rel(elf_file_t ef, GElf_Addr address, size_t len, void *dest)
187 {
188 GElf_Off secofs;
189 GElf_Rel *r;
190 GElf_Rela *a;
191 GElf_Addr secbase, dataoff;
192 int error, i, sec;
193
194 /* Find out which section contains the data. */
195 sec = -1;
196 for (i = 0; i < ef->nprogtab; i++) {
197 if (address < ef->progtab[i].addr)
198 continue;
199
200 dataoff = address - ef->progtab[i].addr;
201 if (dataoff + len > ef->progtab[i].size)
202 continue;
203
204 sec = ef->progtab[i].sec;
205 secbase = ef->progtab[i].addr;
206 secofs = ef->progtab[i].offset;
207 break;
208 }
209
210 if (sec == -1) {
211 if (ef->ef_verbose)
212 warnx("ef_obj_seg_read_rel(%s): bad address (%jx)",
213 ef->ef_name, (uintmax_t)address);
214 return (EFAULT);
215 }
216
217 if (secofs == (GElf_Off)-1) {
218 memset(dest, 0, len);
219 } else {
220 error = elf_read_raw_data(ef->ef_efile, secofs + dataoff, dest,
221 len);
222 if (error != 0)
223 return (error);
224 }
225
226 /* Now do the relocations. */
227 for (i = 0; i < ef->nrel; i++) {
228 if (ef->reltab[i].sec != sec)
229 continue;
230 for (r = ef->reltab[i].rel;
231 r < &ef->reltab[i].rel[ef->reltab[i].nrel]; r++) {
232 error = elf_reloc(ef->ef_efile, r, ELF_T_REL, secbase,
233 address, len, dest);
234 if (error != 0)
235 return (error);
236 }
237 }
238 for (i = 0; i < ef->nrela; i++) {
239 if (ef->relatab[i].sec != sec)
240 continue;
241 for (a = ef->relatab[i].rela;
242 a < &ef->relatab[i].rela[ef->relatab[i].nrela]; a++) {
243 error = elf_reloc(ef->ef_efile, a, ELF_T_RELA, secbase,
244 address, len, dest);
245 if (error != 0)
246 return (error);
247 }
248 }
249 return (0);
250 }
251
252 static int
ef_obj_seg_read_string(elf_file_t ef,GElf_Addr address,size_t len,char * dest)253 ef_obj_seg_read_string(elf_file_t ef, GElf_Addr address, size_t len, char *dest)
254 {
255 GElf_Off ofs;
256
257 ofs = ef_obj_get_offset(ef, address);
258 if (ofs == 0) {
259 if (ef->ef_verbose)
260 warnx("ef_obj_seg_read_string(%s): bad address (%jx)",
261 ef->ef_name, (uintmax_t)address);
262 return (EFAULT);
263 }
264
265 return (elf_read_raw_string(ef->ef_efile, ofs, dest, len));
266 }
267
268 int
ef_obj_open(struct elf_file * efile,int verbose)269 ef_obj_open(struct elf_file *efile, int verbose)
270 {
271 elf_file_t ef;
272 GElf_Ehdr *hdr;
273 GElf_Shdr *shdr;
274 GElf_Sym *es;
275 GElf_Addr mapbase;
276 size_t i, nshdr;
277 int error, pb, ra, rl;
278 int j, nsym, symstrindex, symtabindex;
279
280 hdr = &efile->ef_hdr;
281 if (hdr->e_type != ET_REL || hdr->e_shnum == 0 || hdr->e_shoff == 0 ||
282 hdr->e_shentsize != elf_object_size(efile, ELF_T_SHDR))
283 return (EFTYPE);
284
285 ef = calloc(1, sizeof(*ef));
286 if (ef == NULL)
287 return (errno);
288
289 efile->ef_ef = ef;
290 efile->ef_ops = &ef_obj_file_ops;
291
292 ef->ef_verbose = verbose;
293 ef->ef_name = strdup(efile->ef_filename);
294 ef->ef_efile = efile;
295
296 error = elf_read_shdrs(efile, &nshdr, &shdr);
297 if (error != 0) {
298 shdr = NULL;
299 goto out;
300 }
301
302 /* Scan the section headers for information and table sizing. */
303 nsym = 0;
304 symtabindex = -1;
305 symstrindex = -1;
306 for (i = 0; i < nshdr; i++) {
307 switch (shdr[i].sh_type) {
308 case SHT_PROGBITS:
309 case SHT_NOBITS:
310 ef->nprogtab++;
311 break;
312 case SHT_SYMTAB:
313 nsym++;
314 symtabindex = i;
315 symstrindex = shdr[i].sh_link;
316 break;
317 case SHT_REL:
318 ef->nrel++;
319 break;
320 case SHT_RELA:
321 ef->nrela++;
322 break;
323 case SHT_STRTAB:
324 break;
325 }
326 }
327
328 if (ef->nprogtab == 0) {
329 warnx("%s: file has no contents", ef->ef_name);
330 goto out;
331 }
332 if (nsym != 1) {
333 warnx("%s: file has no valid symbol table", ef->ef_name);
334 goto out;
335 }
336 if (symstrindex < 0 || symstrindex > nshdr ||
337 shdr[symstrindex].sh_type != SHT_STRTAB) {
338 warnx("%s: file has invalid symbol strings", ef->ef_name);
339 goto out;
340 }
341
342 /* Allocate space for tracking the load chunks */
343 if (ef->nprogtab != 0)
344 ef->progtab = calloc(ef->nprogtab, sizeof(*ef->progtab));
345 if (ef->nrel != 0)
346 ef->reltab = calloc(ef->nrel, sizeof(*ef->reltab));
347 if (ef->nrela != 0)
348 ef->relatab = calloc(ef->nrela, sizeof(*ef->relatab));
349 if ((ef->nprogtab != 0 && ef->progtab == NULL) ||
350 (ef->nrel != 0 && ef->reltab == NULL) ||
351 (ef->nrela != 0 && ef->relatab == NULL)) {
352 warnx("malloc failed");
353 error = ENOMEM;
354 goto out;
355 }
356
357 if (elf_read_symbols(efile, symtabindex, &ef->ddbsymcnt,
358 &ef->ddbsymtab) != 0) {
359 warnx("elf_read_symbols failed");
360 goto out;
361 }
362
363 if (elf_read_string_table(efile, &shdr[symstrindex], &ef->ddbstrcnt,
364 &ef->ddbstrtab) != 0) {
365 warnx("elf_read_string_table failed");
366 goto out;
367 }
368
369 /* Do we have a string table for the section names? */
370 if (hdr->e_shstrndx != 0 &&
371 shdr[hdr->e_shstrndx].sh_type == SHT_STRTAB) {
372 if (elf_read_string_table(efile, &shdr[hdr->e_shstrndx],
373 &ef->shstrcnt, &ef->shstrtab) != 0) {
374 warnx("elf_read_string_table failed");
375 goto out;
376 }
377 }
378
379 /*
380 * Now allocate address space for code/data(progbits) and
381 * bss(nobits) and allocate space for and load relocs.
382 */
383 pb = 0;
384 rl = 0;
385 ra = 0;
386 mapbase = 0;
387 for (i = 0; i < nshdr; i++) {
388 switch (shdr[i].sh_type) {
389 case SHT_PROGBITS:
390 case SHT_NOBITS:
391 mapbase = roundup2(mapbase, shdr[i].sh_addralign);
392 ef->progtab[pb].addr = mapbase;
393 if (shdr[i].sh_type == SHT_PROGBITS) {
394 ef->progtab[pb].name = "<<PROGBITS>>";
395 ef->progtab[pb].offset = shdr[i].sh_offset;
396 } else {
397 ef->progtab[pb].name = "<<NOBITS>>";
398 ef->progtab[pb].offset = (GElf_Off)-1;
399 }
400 ef->progtab[pb].size = shdr[i].sh_size;
401 ef->progtab[pb].sec = i;
402 if (ef->shstrtab && shdr[i].sh_name != 0)
403 ef->progtab[pb].name =
404 ef->shstrtab + shdr[i].sh_name;
405
406 /* Update all symbol values with the offset. */
407 for (j = 0; j < ef->ddbsymcnt; j++) {
408 es = &ef->ddbsymtab[j];
409 if (es->st_shndx != i)
410 continue;
411 es->st_value += ef->progtab[pb].addr;
412 }
413 mapbase += shdr[i].sh_size;
414 pb++;
415 break;
416 case SHT_REL:
417 ef->reltab[rl].sec = shdr[i].sh_info;
418 if (elf_read_rel(efile, i, &ef->reltab[rl].nrel,
419 &ef->reltab[rl].rel) != 0) {
420 warnx("elf_read_rel failed");
421 goto out;
422 }
423 rl++;
424 break;
425 case SHT_RELA:
426 ef->relatab[ra].sec = shdr[i].sh_info;
427 if (elf_read_rela(efile, i, &ef->relatab[ra].nrela,
428 &ef->relatab[ra].rela) != 0) {
429 warnx("elf_read_rela failed");
430 goto out;
431 }
432 ra++;
433 break;
434 }
435 }
436 error = 0;
437 out:
438 free(shdr);
439 if (error != 0)
440 ef_obj_close(ef);
441 return (error);
442 }
443
444 static void
ef_obj_close(elf_file_t ef)445 ef_obj_close(elf_file_t ef)
446 {
447 int i;
448
449 if (ef->ef_name)
450 free(ef->ef_name);
451 if (ef->nprogtab != 0)
452 free(ef->progtab);
453 if (ef->nrel != 0) {
454 for (i = 0; i < ef->nrel; i++)
455 if (ef->reltab[i].rel != NULL)
456 free(ef->reltab[i].rel);
457 free(ef->reltab);
458 }
459 if (ef->nrela != 0) {
460 for (i = 0; i < ef->nrela; i++)
461 if (ef->relatab[i].rela != NULL)
462 free(ef->relatab[i].rela);
463 free(ef->relatab);
464 }
465 if (ef->ddbsymtab != NULL)
466 free(ef->ddbsymtab);
467 if (ef->ddbstrtab != NULL)
468 free(ef->ddbstrtab);
469 if (ef->shstrtab != NULL)
470 free(ef->shstrtab);
471 ef->ef_efile->ef_ops = NULL;
472 ef->ef_efile->ef_ef = NULL;
473 free(ef);
474 }
475