1 /*-
2 * Copyright (c) 2004 Ian Dowse <iedowse@freebsd.org>
3 * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
4 * Copyright (c) 1998 Peter Wemm <peter@freebsd.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 * $FreeBSD: src/sys/boot/common/load_elf_obj.c,v 1.2 2005/12/18 04:52:35 marcel Exp $
29 */
30
31 #include <sys/param.h>
32 #include <sys/exec.h>
33 #include <sys/linker.h>
34 #include <sys/module.h>
35 #include <inttypes.h>
36 #include <string.h>
37 #include <machine/elf.h>
38 #include <stand.h>
39 #define FREEBSD_ELF
40 #include <link.h>
41
42 #include "bootstrap.h"
43
44 #define COPYOUT(s,d,l) archsw.arch_copyout((vm_offset_t)(s), d, l)
45
46 #if defined(__i386__) && __ELF_WORD_SIZE == 64
47 #undef ELF_TARG_CLASS
48 #undef ELF_TARG_MACH
49 #define ELF_TARG_CLASS ELFCLASS64
50 #define ELF_TARG_MACH EM_X86_64
51 #endif
52
53 typedef struct elf_file {
54 Elf_Ehdr hdr;
55 Elf_Shdr *e_shdr;
56
57 int symtabindex; /* Index of symbol table */
58 int shstrindex; /* Index of section name string table */
59
60 int fd;
61 vm_offset_t off;
62 } *elf_file_t;
63
64 static int __elfN(obj_loadimage)(struct preloaded_file *mp, elf_file_t ef,
65 u_int64_t loadaddr);
66 static int __elfN(obj_lookup_set)(struct preloaded_file *mp, elf_file_t ef,
67 const char *name, Elf_Addr *startp, Elf_Addr *stopp, int *countp);
68 static int __elfN(obj_reloc_ptr)(struct preloaded_file *mp, elf_file_t ef,
69 Elf_Addr p, void *val, size_t len);
70 static int __elfN(obj_parse_modmetadata)(struct preloaded_file *mp,
71 elf_file_t ef);
72 static Elf_Addr __elfN(obj_symaddr)(struct elf_file *ef, Elf_Size symidx);
73
74 const char *__elfN(obj_kerneltype) = "elf kernel";
75 const char *__elfN(obj_moduletype) = "elf obj module";
76
77 /*
78 * Attempt to load the file (file) as an ELF module. It will be stored at
79 * (dest), and a pointer to a module structure describing the loaded object
80 * will be saved in (result).
81 */
82 int
__elfN(obj_loadfile)83 __elfN(obj_loadfile)(char *filename, u_int64_t dest,
84 struct preloaded_file **result)
85 {
86 struct preloaded_file *fp, *kfp;
87 struct elf_file ef;
88 Elf_Ehdr *hdr;
89 int err;
90 ssize_t bytes_read;
91
92 fp = NULL;
93 bzero(&ef, sizeof(struct elf_file));
94
95 /*
96 * Open the image, read and validate the ELF header
97 */
98 if (filename == NULL) /* can't handle nameless */
99 return(EFTYPE);
100 if ((ef.fd = rel_open(filename, NULL, O_RDONLY)) == -1)
101 return(errno);
102
103 hdr = &ef.hdr;
104 bytes_read = read(ef.fd, hdr, sizeof(*hdr));
105 if (bytes_read != sizeof(*hdr)) {
106 err = EFTYPE; /* could be EIO, but may be small file */
107 goto oerr;
108 }
109
110 /* Is it ELF? */
111 if (!IS_ELF(*hdr)) {
112 err = EFTYPE;
113 goto oerr;
114 }
115 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS || /* Layout ? */
116 hdr->e_ident[EI_DATA] != ELF_TARG_DATA ||
117 hdr->e_ident[EI_VERSION] != EV_CURRENT || /* Version ? */
118 hdr->e_version != EV_CURRENT ||
119 hdr->e_machine != ELF_TARG_MACH || /* Machine ? */
120 hdr->e_type != ET_REL) {
121 err = EFTYPE;
122 goto oerr;
123 }
124
125 if (hdr->e_shnum * hdr->e_shentsize == 0 || hdr->e_shoff == 0 ||
126 hdr->e_shentsize != sizeof(Elf_Shdr)) {
127 err = EFTYPE;
128 goto oerr;
129 }
130
131 kfp = file_findfile(NULL, NULL);
132 if (kfp == NULL) {
133 printf("elf" __XSTRING(__ELF_WORD_SIZE)
134 "_obj_loadfile: can't load module before kernel\n");
135 err = EPERM;
136 goto oerr;
137 }
138 if (strcmp(__elfN(obj_kerneltype), kfp->f_type)) {
139 printf("elf" __XSTRING(__ELF_WORD_SIZE)
140 "_obj_loadfile: can't load module with kernel type '%s'\n",
141 kfp->f_type);
142 err = EPERM;
143 goto oerr;
144 }
145
146 /* Page-align the load address */
147 dest = roundup(dest, PAGE_SIZE);
148
149 /*
150 * Ok, we think we should handle this.
151 */
152 fp = file_alloc();
153 if (fp == NULL) {
154 printf("elf" __XSTRING(__ELF_WORD_SIZE)
155 "_obj_loadfile: cannot allocate module info\n");
156 err = EPERM;
157 goto out;
158 }
159 fp->f_name = rel_rootpath(filename);
160 fp->f_type = strdup(__elfN(obj_moduletype));
161
162 printf("%s ", filename);
163
164 fp->f_size = __elfN(obj_loadimage)(fp, &ef, dest);
165 if (fp->f_size == 0 || fp->f_addr == 0)
166 goto ioerr;
167
168 /* save exec header as metadata */
169 file_addmetadata(fp, MODINFOMD_ELFHDR, sizeof(*hdr), hdr);
170
171 /* Load OK, return module pointer */
172 *result = (struct preloaded_file *)fp;
173 err = 0;
174 goto out;
175
176 ioerr:
177 err = EIO;
178 oerr:
179 file_discard(fp);
180 out:
181 close(ef.fd);
182 if (ef.e_shdr != NULL)
183 free(ef.e_shdr);
184
185 return(err);
186 }
187
188 /*
189 * With the file (fd) open on the image, and (ehdr) containing
190 * the Elf header, load the image at (off)
191 */
192 static int
__elfN(obj_loadimage)193 __elfN(obj_loadimage)(struct preloaded_file *fp, elf_file_t ef, u_int64_t off)
194 {
195 Elf_Ehdr *hdr;
196 Elf_Shdr *shdr;
197 vm_offset_t firstaddr, lastaddr;
198 int i, nsym, res, ret, shdrbytes, symstrindex;
199
200 ret = 0;
201 firstaddr = lastaddr = (vm_offset_t)off;
202 hdr = &ef->hdr;
203 ef->off = (vm_offset_t)off;
204
205 /* Read in the section headers. */
206 shdrbytes = hdr->e_shnum * hdr->e_shentsize;
207 shdr = alloc_pread(ef->fd, (off_t)hdr->e_shoff, shdrbytes);
208 if (shdr == NULL) {
209 printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
210 "_obj_loadimage: read section headers failed\n");
211 goto out;
212 }
213 ef->e_shdr = shdr;
214
215 /*
216 * Decide where to load everything, but don't read it yet.
217 * We store the load address as a non-zero sh_addr value.
218 * Start with the code/data and bss.
219 */
220 for (i = 0; i < hdr->e_shnum; i++) {
221 shdr[i].sh_addr = 0;
222 if (shdr[i].sh_size == 0)
223 continue;
224 switch (shdr[i].sh_type) {
225 case SHT_PROGBITS:
226 case SHT_NOBITS:
227 lastaddr = roundup(lastaddr, shdr[i].sh_addralign);
228 shdr[i].sh_addr = (Elf_Addr)lastaddr;
229 lastaddr += shdr[i].sh_size;
230 break;
231 }
232 }
233
234 /* Symbols. */
235 nsym = 0;
236 for (i = 0; i < hdr->e_shnum; i++) {
237 switch (shdr[i].sh_type) {
238 case SHT_SYMTAB:
239 nsym++;
240 ef->symtabindex = i;
241 shdr[i].sh_addr = (Elf_Addr)lastaddr;
242 lastaddr += shdr[i].sh_size;
243 break;
244 }
245 }
246 if (nsym != 1) {
247 printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
248 "_obj_loadimage: file has no valid symbol table\n");
249 goto out;
250 }
251 lastaddr = roundup(lastaddr, shdr[ef->symtabindex].sh_addralign);
252 shdr[ef->symtabindex].sh_addr = (Elf_Addr)lastaddr;
253 lastaddr += shdr[ef->symtabindex].sh_size;
254
255 symstrindex = shdr[ef->symtabindex].sh_link;
256 if (symstrindex < 0 || symstrindex >= hdr->e_shnum ||
257 shdr[symstrindex].sh_type != SHT_STRTAB) {
258 printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
259 "_obj_loadimage: file has invalid symbol strings\n");
260 goto out;
261 }
262 lastaddr = roundup(lastaddr, shdr[symstrindex].sh_addralign);
263 shdr[symstrindex].sh_addr = (Elf_Addr)lastaddr;
264 lastaddr += shdr[symstrindex].sh_size;
265
266 /* Section names. */
267 if (hdr->e_shstrndx == 0 || hdr->e_shstrndx >= hdr->e_shnum ||
268 shdr[hdr->e_shstrndx].sh_type != SHT_STRTAB) {
269 printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
270 "_obj_loadimage: file has no section names\n");
271 goto out;
272 }
273 ef->shstrindex = hdr->e_shstrndx;
274 lastaddr = roundup(lastaddr, shdr[ef->shstrindex].sh_addralign);
275 shdr[ef->shstrindex].sh_addr = (Elf_Addr)lastaddr;
276 lastaddr += shdr[ef->shstrindex].sh_size;
277
278 /* Relocation tables. */
279 for (i = 0; i < hdr->e_shnum; i++) {
280 switch (shdr[i].sh_type) {
281 case SHT_REL:
282 case SHT_RELA:
283 lastaddr = roundup(lastaddr, shdr[i].sh_addralign);
284 shdr[i].sh_addr = (Elf_Addr)lastaddr;
285 lastaddr += shdr[i].sh_size;
286 break;
287 }
288 }
289
290 /* Clear the whole area, including bss regions. */
291 kern_bzero(firstaddr, lastaddr - firstaddr);
292
293 /* Now read it all in. */
294 for (i = 0; i < hdr->e_shnum; i++) {
295 if (shdr[i].sh_addr == 0 || shdr[i].sh_type == SHT_NOBITS)
296 continue;
297 if (kern_pread(ef->fd, (vm_offset_t)shdr[i].sh_addr,
298 shdr[i].sh_size, (off_t)shdr[i].sh_offset) != 0) {
299 printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
300 "_obj_loadimage: read failed\n");
301 goto out;
302 }
303 }
304
305 file_addmetadata(fp, MODINFOMD_SHDR, shdrbytes, shdr);
306
307 res = __elfN(obj_parse_modmetadata)(fp, ef);
308 if (res != 0)
309 goto out;
310
311 ret = lastaddr - firstaddr;
312 fp->f_addr = firstaddr;
313
314 printf("size 0x%lx at 0x%lx", (u_long)ret, (u_long)firstaddr);
315
316 out:
317 printf("\n");
318 return ret;
319 }
320
321 #if defined(__i386__) && __ELF_WORD_SIZE == 64
322 struct mod_metadata64 {
323 int md_version; /* structure version MDTV_* */
324 int md_type; /* type of entry MDT_* */
325 u_int64_t md_data; /* specific data */
326 u_int64_t md_cval; /* common string label */
327 };
328 #endif
329
330 int
__elfN(obj_parse_modmetadata)331 __elfN(obj_parse_modmetadata)(struct preloaded_file *fp, elf_file_t ef)
332 {
333 struct mod_metadata md;
334 #if defined(__i386__) && __ELF_WORD_SIZE == 64
335 struct mod_metadata64 md64;
336 #endif
337 struct mod_depend *mdepend;
338 struct mod_version mver;
339 char *s;
340 int error, modcnt, minfolen;
341 Elf_Addr v, p, p_stop;
342
343 if (__elfN(obj_lookup_set)(fp, ef, "modmetadata_set", &p, &p_stop,
344 &modcnt) != 0)
345 return ENOENT;
346
347 modcnt = 0;
348 while (p < p_stop) {
349 COPYOUT(p, &v, sizeof(v));
350 error = __elfN(obj_reloc_ptr)(fp, ef, p, &v, sizeof(v));
351 if (error != 0)
352 return (error);
353 #if defined(__i386__) && __ELF_WORD_SIZE == 64
354 COPYOUT(v, &md64, sizeof(md64));
355 error = __elfN(obj_reloc_ptr)(fp, ef, v, &md64, sizeof(md64));
356 if (error != 0)
357 return (error);
358 md.md_version = md64.md_version;
359 md.md_type = md64.md_type;
360 md.md_cval = (const char *)(uintptr_t)md64.md_cval;
361 md.md_data = (void *)(uintptr_t)md64.md_data;
362 #else
363 COPYOUT(v, &md, sizeof(md));
364 error = __elfN(obj_reloc_ptr)(fp, ef, v, &md, sizeof(md));
365 if (error != 0)
366 return (error);
367 #endif
368 p += sizeof(Elf_Addr);
369 switch(md.md_type) {
370 case MDT_DEPEND:
371 s = strdupout((vm_offset_t)md.md_cval);
372 minfolen = sizeof(*mdepend) + strlen(s) + 1;
373 mdepend = malloc(minfolen);
374 if (mdepend == NULL)
375 return ENOMEM;
376 COPYOUT((vm_offset_t)md.md_data, mdepend,
377 sizeof(*mdepend));
378 strcpy((char*)(mdepend + 1), s);
379 free(s);
380 file_addmetadata(fp, MODINFOMD_DEPLIST, minfolen,
381 mdepend);
382 free(mdepend);
383 break;
384 case MDT_VERSION:
385 s = strdupout((vm_offset_t)md.md_cval);
386 COPYOUT((vm_offset_t)md.md_data, &mver, sizeof(mver));
387 file_addmodule(fp, s, mver.mv_version, NULL);
388 free(s);
389 modcnt++;
390 break;
391 case MDT_MODULE:
392 break;
393 default:
394 printf("unknown type %d\n", md.md_type);
395 break;
396 }
397 }
398 return 0;
399 }
400
401 static int
__elfN(obj_lookup_set)402 __elfN(obj_lookup_set)(struct preloaded_file *fp, elf_file_t ef,
403 const char* name, Elf_Addr *startp, Elf_Addr *stopp, int *countp)
404 {
405 Elf_Ehdr *hdr;
406 Elf_Shdr *shdr;
407 char *p;
408 vm_offset_t shstrtab;
409 int i;
410
411 hdr = &ef->hdr;
412 shdr = ef->e_shdr;
413 shstrtab = shdr[ef->shstrindex].sh_addr;
414
415 for (i = 0; i < hdr->e_shnum; i++) {
416 if (shdr[i].sh_type != SHT_PROGBITS)
417 continue;
418 if (shdr[i].sh_name == 0)
419 continue;
420 p = strdupout(shstrtab + shdr[i].sh_name);
421 if (strncmp(p, "set_", 4) == 0 && strcmp(p + 4, name) == 0) {
422 *startp = shdr[i].sh_addr;
423 *stopp = shdr[i].sh_addr + shdr[i].sh_size;
424 *countp = (*stopp - *startp) / sizeof(Elf_Addr);
425 free(p);
426 return (0);
427 }
428 free(p);
429 }
430
431 return (ESRCH);
432 }
433
434 /*
435 * Apply any intra-module relocations to the value. p is the load address
436 * of the value and val/len is the value to be modified. This does NOT modify
437 * the image in-place, because this is done by kern_linker later on.
438 */
439 static int
__elfN(obj_reloc_ptr)440 __elfN(obj_reloc_ptr)(struct preloaded_file *mp, elf_file_t ef, Elf_Addr p,
441 void *val, size_t len)
442 {
443 Elf_Ehdr *hdr;
444 Elf_Shdr *shdr;
445 Elf_Addr off = p;
446 Elf_Addr base;
447 Elf_Rela a, *abase;
448 Elf_Rel r, *rbase;
449 int error, i, j, nrel, nrela;
450
451 hdr = &ef->hdr;
452 shdr = ef->e_shdr;
453
454 for (i = 0; i < hdr->e_shnum; i++) {
455 if (shdr[i].sh_type != SHT_RELA && shdr[i].sh_type != SHT_REL)
456 continue;
457 base = shdr[shdr[i].sh_info].sh_addr;
458 if (base == 0 || shdr[i].sh_addr == 0)
459 continue;
460 if (off < base || off + len > base +
461 shdr[shdr[i].sh_info].sh_size)
462 continue;
463
464 switch (shdr[i].sh_type) {
465 case SHT_RELA:
466 abase = (Elf_Rela *)(intptr_t)shdr[i].sh_addr;
467
468 nrela = shdr[i].sh_size / sizeof(Elf_Rela);
469 for (j = 0; j < nrela; j++) {
470 COPYOUT(abase + j, &a, sizeof(a));
471
472 error = __elfN(reloc)(ef, __elfN(obj_symaddr),
473 &a, ELF_RELOC_RELA, base, off, val, len);
474 if (error != 0)
475 return (error);
476 }
477 break;
478 case SHT_REL:
479 rbase = (Elf_Rel *)(intptr_t)shdr[i].sh_addr;
480
481 nrel = shdr[i].sh_size / sizeof(Elf_Rel);
482 for (j = 0; j < nrel; j++) {
483 COPYOUT(rbase + j, &r, sizeof(r));
484
485 error = __elfN(reloc)(ef, __elfN(obj_symaddr),
486 &r, ELF_RELOC_REL, base, off, val, len);
487 if (error != 0)
488 return (error);
489 }
490 break;
491 }
492 }
493 return (0);
494 }
495
496 /* Look up the address of a specified symbol. */
497 static Elf_Addr
__elfN(obj_symaddr)498 __elfN(obj_symaddr)(struct elf_file *ef, Elf_Size symidx)
499 {
500 Elf_Sym sym;
501 Elf_Addr base;
502
503 if (symidx >= ef->e_shdr[ef->symtabindex].sh_size / sizeof(Elf_Sym))
504 return (0);
505 COPYOUT(ef->e_shdr[ef->symtabindex].sh_addr + symidx * sizeof(Elf_Sym),
506 &sym, sizeof(sym));
507 if (sym.st_shndx == SHN_UNDEF || sym.st_shndx >= ef->hdr.e_shnum)
508 return (0);
509 base = ef->e_shdr[sym.st_shndx].sh_addr;
510 if (base == 0)
511 return (0);
512 return (base + sym.st_value);
513 }
514