load_elf_obj.c revision 210423
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
29#include <sys/cdefs.h>
30__FBSDID("$FreeBSD: head/sys/boot/common/load_elf_obj.c 210423 2010-07-23 17:07:51Z avg $");
31
32#include <sys/param.h>
33#include <sys/exec.h>
34#include <sys/linker.h>
35#include <sys/module.h>
36#include <inttypes.h>
37#include <string.h>
38#include <machine/elf.h>
39#include <stand.h>
40#define FREEBSD_ELF
41#include <link.h>
42
43#include "bootstrap.h"
44
45#define COPYOUT(s,d,l)	archsw.arch_copyout((vm_offset_t)(s), d, l)
46
47#if defined(__i386__) && __ELF_WORD_SIZE == 64
48#undef ELF_TARG_CLASS
49#undef ELF_TARG_MACH
50#define ELF_TARG_CLASS  ELFCLASS64
51#define ELF_TARG_MACH   EM_X86_64
52#endif
53
54typedef struct elf_file {
55	Elf_Ehdr	hdr;
56	Elf_Shdr	*e_shdr;
57
58	int		symtabindex;	/* Index of symbol table */
59	int		shstrindex;	/* Index of section name string table */
60
61	int		fd;
62	vm_offset_t	off;
63} *elf_file_t;
64
65static int __elfN(obj_loadimage)(struct preloaded_file *mp, elf_file_t ef,
66    u_int64_t loadaddr);
67static int __elfN(obj_lookup_set)(struct preloaded_file *mp, elf_file_t ef,
68    const char *name, Elf_Addr *startp, Elf_Addr *stopp, int *countp);
69static int __elfN(obj_reloc_ptr)(struct preloaded_file *mp, elf_file_t ef,
70    Elf_Addr p, void *val, size_t len);
71static int __elfN(obj_parse_modmetadata)(struct preloaded_file *mp,
72    elf_file_t ef);
73static Elf_Addr __elfN(obj_symaddr)(struct elf_file *ef, Elf_Size symidx);
74
75const char	*__elfN(obj_kerneltype) = "elf kernel";
76const char	*__elfN(obj_moduletype) = "elf obj module";
77
78/*
79 * Attempt to load the file (file) as an ELF module.  It will be stored at
80 * (dest), and a pointer to a module structure describing the loaded object
81 * will be saved in (result).
82 */
83int
84__elfN(obj_loadfile)(char *filename, u_int64_t dest,
85    struct preloaded_file **result)
86{
87	struct preloaded_file *fp, *kfp;
88	struct elf_file	ef;
89	Elf_Ehdr *hdr;
90	int err;
91	ssize_t bytes_read;
92
93	fp = NULL;
94	bzero(&ef, sizeof(struct elf_file));
95
96	/*
97	 * Open the image, read and validate the ELF header
98	 */
99	if (filename == NULL)	/* can't handle nameless */
100		return(EFTYPE);
101	if ((ef.fd = open(filename, O_RDONLY)) == -1)
102		return(errno);
103
104	hdr = &ef.hdr;
105	bytes_read = read(ef.fd, hdr, sizeof(*hdr));
106	if (bytes_read != sizeof(*hdr)) {
107		err = EFTYPE;	/* could be EIO, but may be small file */
108		goto oerr;
109	}
110
111	/* Is it ELF? */
112	if (!IS_ELF(*hdr)) {
113		err = EFTYPE;
114		goto oerr;
115	}
116	if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||	/* Layout ? */
117	    hdr->e_ident[EI_DATA] != ELF_TARG_DATA ||
118	    hdr->e_ident[EI_VERSION] != EV_CURRENT ||	/* Version ? */
119	    hdr->e_version != EV_CURRENT ||
120	    hdr->e_machine != ELF_TARG_MACH ||		/* Machine ? */
121	    hdr->e_type != ET_REL) {
122		err = EFTYPE;
123		goto oerr;
124	}
125
126	if (hdr->e_shnum * hdr->e_shentsize == 0 || hdr->e_shoff == 0 ||
127	    hdr->e_shentsize != sizeof(Elf_Shdr)) {
128		err = EFTYPE;
129		goto oerr;
130	}
131
132	kfp = file_findfile(NULL, NULL);
133	if (kfp == NULL) {
134		printf("elf" __XSTRING(__ELF_WORD_SIZE)
135		    "_obj_loadfile: can't load module before kernel\n");
136		err = EPERM;
137		goto oerr;
138	}
139	if (strcmp(__elfN(obj_kerneltype), kfp->f_type)) {
140		printf("elf" __XSTRING(__ELF_WORD_SIZE)
141		    "_obj_loadfile: can't load module with kernel type '%s'\n",
142		    kfp->f_type);
143		err = EPERM;
144		goto oerr;
145	}
146
147	/* Page-align the load address */
148	dest = roundup(dest, PAGE_SIZE);
149
150	/*
151	 * Ok, we think we should handle this.
152	 */
153	fp = file_alloc();
154	if (fp == NULL) {
155		printf("elf" __XSTRING(__ELF_WORD_SIZE)
156		    "_obj_loadfile: cannot allocate module info\n");
157		err = EPERM;
158		goto out;
159	}
160	fp->f_name = strdup(filename);
161	fp->f_type = strdup(__elfN(obj_moduletype));
162
163	printf("%s ", filename);
164
165	fp->f_size = __elfN(obj_loadimage)(fp, &ef, dest);
166	if (fp->f_size == 0 || fp->f_addr == 0)
167		goto ioerr;
168
169	/* save exec header as metadata */
170	file_addmetadata(fp, MODINFOMD_ELFHDR, sizeof(*hdr), hdr);
171
172	/* Load OK, return module pointer */
173	*result = (struct preloaded_file *)fp;
174	err = 0;
175	goto out;
176
177ioerr:
178	err = EIO;
179oerr:
180	file_discard(fp);
181out:
182	close(ef.fd);
183	if (ef.e_shdr != NULL)
184		free(ef.e_shdr);
185
186	return(err);
187}
188
189/*
190 * With the file (fd) open on the image, and (ehdr) containing
191 * the Elf header, load the image at (off)
192 */
193static int
194__elfN(obj_loadimage)(struct preloaded_file *fp, elf_file_t ef, u_int64_t off)
195{
196	Elf_Ehdr *hdr;
197	Elf_Shdr *shdr;
198	vm_offset_t firstaddr, lastaddr;
199	int i, nsym, res, ret, shdrbytes, symstrindex;
200
201	ret = 0;
202	firstaddr = lastaddr = (vm_offset_t)off;
203	hdr = &ef->hdr;
204	ef->off = (vm_offset_t)off;
205
206	/* Read in the section headers. */
207	shdrbytes = hdr->e_shnum * hdr->e_shentsize;
208	shdr = alloc_pread(ef->fd, (off_t)hdr->e_shoff, shdrbytes);
209	if (shdr == NULL) {
210		printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
211		    "_obj_loadimage: read section headers failed\n");
212		goto out;
213	}
214	ef->e_shdr = shdr;
215
216	/*
217	 * Decide where to load everything, but don't read it yet.
218	 * We store the load address as a non-zero sh_addr value.
219	 * Start with the code/data and bss.
220	 */
221	for (i = 0; i < hdr->e_shnum; i++)
222		shdr[i].sh_addr = 0;
223	for (i = 0; i < hdr->e_shnum; i++) {
224		if (shdr[i].sh_size == 0)
225			continue;
226		switch (shdr[i].sh_type) {
227		case SHT_PROGBITS:
228		case SHT_NOBITS:
229			lastaddr = roundup(lastaddr, shdr[i].sh_addralign);
230			shdr[i].sh_addr = (Elf_Addr)lastaddr;
231			lastaddr += shdr[i].sh_size;
232			break;
233		}
234	}
235
236	/* Symbols. */
237	nsym = 0;
238	for (i = 0; i < hdr->e_shnum; i++) {
239		switch (shdr[i].sh_type) {
240		case SHT_SYMTAB:
241			nsym++;
242			ef->symtabindex = i;
243			shdr[i].sh_addr = (Elf_Addr)lastaddr;
244			lastaddr += shdr[i].sh_size;
245			break;
246		}
247	}
248	if (nsym != 1) {
249		printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
250		    "_obj_loadimage: file has no valid symbol table\n");
251		goto out;
252	}
253	lastaddr = roundup(lastaddr, shdr[ef->symtabindex].sh_addralign);
254	shdr[ef->symtabindex].sh_addr = (Elf_Addr)lastaddr;
255	lastaddr += shdr[ef->symtabindex].sh_size;
256
257	symstrindex = shdr[ef->symtabindex].sh_link;
258	if (symstrindex < 0 || symstrindex >= hdr->e_shnum ||
259	    shdr[symstrindex].sh_type != SHT_STRTAB) {
260		printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
261		    "_obj_loadimage: file has invalid symbol strings\n");
262		goto out;
263	}
264	lastaddr = roundup(lastaddr, shdr[symstrindex].sh_addralign);
265	shdr[symstrindex].sh_addr = (Elf_Addr)lastaddr;
266	lastaddr += shdr[symstrindex].sh_size;
267
268	/* Section names. */
269	if (hdr->e_shstrndx == 0 || hdr->e_shstrndx >= hdr->e_shnum ||
270	    shdr[hdr->e_shstrndx].sh_type != SHT_STRTAB) {
271		printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
272		    "_obj_loadimage: file has no section names\n");
273		goto out;
274	}
275	ef->shstrindex = hdr->e_shstrndx;
276	lastaddr = roundup(lastaddr, shdr[ef->shstrindex].sh_addralign);
277	shdr[ef->shstrindex].sh_addr = (Elf_Addr)lastaddr;
278	lastaddr += shdr[ef->shstrindex].sh_size;
279
280	/* Relocation tables. */
281	for (i = 0; i < hdr->e_shnum; i++) {
282		switch (shdr[i].sh_type) {
283		case SHT_REL:
284		case SHT_RELA:
285			lastaddr = roundup(lastaddr, shdr[i].sh_addralign);
286			shdr[i].sh_addr = (Elf_Addr)lastaddr;
287			lastaddr += shdr[i].sh_size;
288			break;
289		}
290	}
291
292	/* Clear the whole area, including bss regions. */
293	kern_bzero(firstaddr, lastaddr - firstaddr);
294
295	/* Now read it all in. */
296	for (i = 0; i < hdr->e_shnum; i++) {
297		if (shdr[i].sh_addr == 0 || shdr[i].sh_type == SHT_NOBITS)
298			continue;
299		if (kern_pread(ef->fd, (vm_offset_t)shdr[i].sh_addr,
300		    shdr[i].sh_size, (off_t)shdr[i].sh_offset) != 0) {
301			printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
302			    "_obj_loadimage: read failed\n");
303			goto out;
304		}
305	}
306
307	file_addmetadata(fp, MODINFOMD_SHDR, shdrbytes, shdr);
308
309	res = __elfN(obj_parse_modmetadata)(fp, ef);
310	if (res != 0)
311		goto out;
312
313	ret = lastaddr - firstaddr;
314	fp->f_addr = firstaddr;
315
316	printf("size 0x%lx at 0x%lx", (u_long)ret, (u_long)firstaddr);
317
318out:
319	printf("\n");
320	return ret;
321}
322
323#if defined(__i386__) && __ELF_WORD_SIZE == 64
324struct mod_metadata64 {
325	int		md_version;	/* structure version MDTV_* */
326	int		md_type;	/* type of entry MDT_* */
327	u_int64_t	md_data;	/* specific data */
328	u_int64_t	md_cval;	/* common string label */
329};
330#endif
331
332int
333__elfN(obj_parse_modmetadata)(struct preloaded_file *fp, elf_file_t ef)
334{
335	struct mod_metadata md;
336#if defined(__i386__) && __ELF_WORD_SIZE == 64
337	struct mod_metadata64 md64;
338#endif
339	struct mod_depend *mdepend;
340	struct mod_version mver;
341	char *s;
342	int error, modcnt, minfolen;
343	Elf_Addr v, p, p_stop;
344
345	if (__elfN(obj_lookup_set)(fp, ef, "modmetadata_set", &p, &p_stop,
346	    &modcnt) != 0)
347		return ENOENT;
348
349	modcnt = 0;
350	while (p < p_stop) {
351		COPYOUT(p, &v, sizeof(v));
352		error = __elfN(obj_reloc_ptr)(fp, ef, p, &v, sizeof(v));
353		if (error != 0)
354			return (error);
355#if defined(__i386__) && __ELF_WORD_SIZE == 64
356		COPYOUT(v, &md64, sizeof(md64));
357		error = __elfN(obj_reloc_ptr)(fp, ef, v, &md64, sizeof(md64));
358		if (error != 0)
359			return (error);
360		md.md_version = md64.md_version;
361		md.md_type = md64.md_type;
362		md.md_cval = (const char *)(uintptr_t)md64.md_cval;
363		md.md_data = (void *)(uintptr_t)md64.md_data;
364#else
365		COPYOUT(v, &md, sizeof(md));
366		error = __elfN(obj_reloc_ptr)(fp, ef, v, &md, sizeof(md));
367		if (error != 0)
368			return (error);
369#endif
370		p += sizeof(Elf_Addr);
371		switch(md.md_type) {
372		case MDT_DEPEND:
373			s = strdupout((vm_offset_t)md.md_cval);
374			minfolen = sizeof(*mdepend) + strlen(s) + 1;
375			mdepend = malloc(minfolen);
376			if (mdepend == NULL)
377				return ENOMEM;
378			COPYOUT((vm_offset_t)md.md_data, mdepend,
379			    sizeof(*mdepend));
380			strcpy((char*)(mdepend + 1), s);
381			free(s);
382			file_addmetadata(fp, MODINFOMD_DEPLIST, minfolen,
383			    mdepend);
384			free(mdepend);
385			break;
386		case MDT_VERSION:
387			s = strdupout((vm_offset_t)md.md_cval);
388			COPYOUT((vm_offset_t)md.md_data, &mver, sizeof(mver));
389			file_addmodule(fp, s, mver.mv_version, NULL);
390			free(s);
391			modcnt++;
392			break;
393		case MDT_MODULE:
394			break;
395		default:
396			printf("unknown type %d\n", md.md_type);
397			break;
398		}
399	}
400	return 0;
401}
402
403static int
404__elfN(obj_lookup_set)(struct preloaded_file *fp, elf_file_t ef,
405    const char* name, Elf_Addr *startp, Elf_Addr *stopp, int *countp)
406{
407	Elf_Ehdr *hdr;
408	Elf_Shdr *shdr;
409	char *p;
410	vm_offset_t shstrtab;
411	int i;
412
413	hdr = &ef->hdr;
414	shdr = ef->e_shdr;
415	shstrtab = shdr[ef->shstrindex].sh_addr;
416
417	for (i = 0; i < hdr->e_shnum; i++) {
418		if (shdr[i].sh_type != SHT_PROGBITS)
419			continue;
420		if (shdr[i].sh_name == 0)
421			continue;
422		p = strdupout(shstrtab + shdr[i].sh_name);
423		if (strncmp(p, "set_", 4) == 0 && strcmp(p + 4, name) == 0) {
424			*startp = shdr[i].sh_addr;
425			*stopp = shdr[i].sh_addr +  shdr[i].sh_size;
426			*countp = (*stopp - *startp) / sizeof(Elf_Addr);
427			free(p);
428			return (0);
429		}
430		free(p);
431	}
432
433	return (ESRCH);
434}
435
436/*
437 * Apply any intra-module relocations to the value. p is the load address
438 * of the value and val/len is the value to be modified. This does NOT modify
439 * the image in-place, because this is done by kern_linker later on.
440 */
441static int
442__elfN(obj_reloc_ptr)(struct preloaded_file *mp, elf_file_t ef, Elf_Addr p,
443    void *val, size_t len)
444{
445	Elf_Ehdr *hdr;
446	Elf_Shdr *shdr;
447	Elf_Addr off = p;
448	Elf_Addr base;
449	Elf_Rela a, *abase;
450	Elf_Rel r, *rbase;
451	int error, i, j, nrel, nrela;
452
453	hdr = &ef->hdr;
454	shdr = ef->e_shdr;
455
456	for (i = 0; i < hdr->e_shnum; i++) {
457		if (shdr[i].sh_type != SHT_RELA && shdr[i].sh_type != SHT_REL)
458			continue;
459		base = shdr[shdr[i].sh_info].sh_addr;
460		if (base == 0 || shdr[i].sh_addr == 0)
461			continue;
462		if (off < base || off + len > base +
463		    shdr[shdr[i].sh_info].sh_size)
464			continue;
465
466		switch (shdr[i].sh_type) {
467		case SHT_RELA:
468			abase = (Elf_Rela *)(intptr_t)shdr[i].sh_addr;
469
470			nrela = shdr[i].sh_size / sizeof(Elf_Rela);
471			for (j = 0; j < nrela; j++) {
472				COPYOUT(abase + j, &a, sizeof(a));
473
474				error = __elfN(reloc)(ef, __elfN(obj_symaddr),
475				    &a, ELF_RELOC_RELA, base, off, val, len);
476				if (error != 0)
477					return (error);
478			}
479			break;
480		case SHT_REL:
481			rbase = (Elf_Rel *)(intptr_t)shdr[i].sh_addr;
482
483			nrel = shdr[i].sh_size / sizeof(Elf_Rel);
484			for (j = 0; j < nrel; j++) {
485				COPYOUT(rbase + j, &r, sizeof(r));
486
487				error = __elfN(reloc)(ef, __elfN(obj_symaddr),
488				    &r, ELF_RELOC_REL, base, off, val, len);
489				if (error != 0)
490					return (error);
491			}
492			break;
493		}
494	}
495	return (0);
496}
497
498/* Look up the address of a specified symbol. */
499static Elf_Addr
500__elfN(obj_symaddr)(struct elf_file *ef, Elf_Size symidx)
501{
502	Elf_Sym sym;
503	Elf_Addr base;
504	int symcnt;
505
506	symcnt = ef->e_shdr[ef->symtabindex].sh_size / sizeof(Elf_Sym);
507	if (symidx >= symcnt)
508		return (0);
509	COPYOUT(ef->e_shdr[ef->symtabindex].sh_addr + symidx * sizeof(Elf_Sym),
510	    &sym, sizeof(sym));
511	if (sym.st_shndx == SHN_UNDEF || sym.st_shndx >= ef->hdr.e_shnum)
512		return (0);
513	base = ef->e_shdr[sym.st_shndx].sh_addr;
514	if (base == 0)
515		return (0);
516	return (base + sym.st_value);
517}
518