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("$FreeBSD$");
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 
54 typedef 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 
65 static int __elfN(obj_loadimage)(struct preloaded_file *mp, elf_file_t ef,
66     u_int64_t loadaddr);
67 static 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);
69 static int __elfN(obj_reloc_ptr)(struct preloaded_file *mp, elf_file_t ef,
70     Elf_Addr p, void *val, size_t len);
71 static int __elfN(obj_parse_modmetadata)(struct preloaded_file *mp,
72     elf_file_t ef);
73 static Elf_Addr __elfN(obj_symaddr)(struct elf_file *ef, Elf_Size symidx);
74 
75 const char	*__elfN(obj_kerneltype) = "elf kernel";
76 const 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  */
83 int
__elfN(obj_loadfile)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, __elfN(obj_kerneltype));
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 
140 	if (archsw.arch_loadaddr != NULL)
141 		dest = archsw.arch_loadaddr(LOAD_ELF, hdr, dest);
142 	else
143 		dest = roundup(dest, PAGE_SIZE);
144 
145 	/*
146 	 * Ok, we think we should handle this.
147 	 */
148 	fp = file_alloc();
149 	if (fp == NULL) {
150 		printf("elf" __XSTRING(__ELF_WORD_SIZE)
151 		    "_obj_loadfile: cannot allocate module info\n");
152 		err = EPERM;
153 		goto out;
154 	}
155 	fp->f_name = strdup(filename);
156 	fp->f_type = strdup(__elfN(obj_moduletype));
157 
158 	printf("%s ", filename);
159 
160 	fp->f_size = __elfN(obj_loadimage)(fp, &ef, dest);
161 	if (fp->f_size == 0 || fp->f_addr == 0)
162 		goto ioerr;
163 
164 	/* save exec header as metadata */
165 	file_addmetadata(fp, MODINFOMD_ELFHDR, sizeof(*hdr), hdr);
166 
167 	/* Load OK, return module pointer */
168 	*result = (struct preloaded_file *)fp;
169 	err = 0;
170 	goto out;
171 
172 ioerr:
173 	err = EIO;
174 oerr:
175 	file_discard(fp);
176 out:
177 	close(ef.fd);
178 	if (ef.e_shdr != NULL)
179 		free(ef.e_shdr);
180 
181 	return(err);
182 }
183 
184 /*
185  * With the file (fd) open on the image, and (ehdr) containing
186  * the Elf header, load the image at (off)
187  */
188 static int
__elfN(obj_loadimage)189 __elfN(obj_loadimage)(struct preloaded_file *fp, elf_file_t ef, u_int64_t off)
190 {
191 	Elf_Ehdr *hdr;
192 	Elf_Shdr *shdr, *cshdr, *lshdr;
193 	vm_offset_t firstaddr, lastaddr;
194 	int i, nsym, res, ret, shdrbytes, symstrindex;
195 
196 	ret = 0;
197 	firstaddr = lastaddr = (vm_offset_t)off;
198 	hdr = &ef->hdr;
199 	ef->off = (vm_offset_t)off;
200 
201 	/* Read in the section headers. */
202 	shdrbytes = hdr->e_shnum * hdr->e_shentsize;
203 	shdr = alloc_pread(ef->fd, (off_t)hdr->e_shoff, shdrbytes);
204 	if (shdr == NULL) {
205 		printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
206 		    "_obj_loadimage: read section headers failed\n");
207 		goto out;
208 	}
209 	ef->e_shdr = shdr;
210 
211 	/*
212 	 * Decide where to load everything, but don't read it yet.
213 	 * We store the load address as a non-zero sh_addr value.
214 	 * Start with the code/data and bss.
215 	 */
216 	for (i = 0; i < hdr->e_shnum; i++)
217 		shdr[i].sh_addr = 0;
218 	for (i = 0; i < hdr->e_shnum; i++) {
219 		if (shdr[i].sh_size == 0)
220 			continue;
221 		switch (shdr[i].sh_type) {
222 		case SHT_PROGBITS:
223 		case SHT_NOBITS:
224 			lastaddr = roundup(lastaddr, shdr[i].sh_addralign);
225 			shdr[i].sh_addr = (Elf_Addr)lastaddr;
226 			lastaddr += shdr[i].sh_size;
227 			break;
228 		}
229 	}
230 
231 	/* Symbols. */
232 	nsym = 0;
233 	for (i = 0; i < hdr->e_shnum; i++) {
234 		switch (shdr[i].sh_type) {
235 		case SHT_SYMTAB:
236 			nsym++;
237 			ef->symtabindex = i;
238 			shdr[i].sh_addr = (Elf_Addr)lastaddr;
239 			lastaddr += shdr[i].sh_size;
240 			break;
241 		}
242 	}
243 	if (nsym != 1) {
244 		printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
245 		    "_obj_loadimage: file has no valid symbol table\n");
246 		goto out;
247 	}
248 	lastaddr = roundup(lastaddr, shdr[ef->symtabindex].sh_addralign);
249 	shdr[ef->symtabindex].sh_addr = (Elf_Addr)lastaddr;
250 	lastaddr += shdr[ef->symtabindex].sh_size;
251 
252 	symstrindex = shdr[ef->symtabindex].sh_link;
253 	if (symstrindex < 0 || symstrindex >= hdr->e_shnum ||
254 	    shdr[symstrindex].sh_type != SHT_STRTAB) {
255 		printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
256 		    "_obj_loadimage: file has invalid symbol strings\n");
257 		goto out;
258 	}
259 	lastaddr = roundup(lastaddr, shdr[symstrindex].sh_addralign);
260 	shdr[symstrindex].sh_addr = (Elf_Addr)lastaddr;
261 	lastaddr += shdr[symstrindex].sh_size;
262 
263 	/* Section names. */
264 	if (hdr->e_shstrndx == 0 || hdr->e_shstrndx >= hdr->e_shnum ||
265 	    shdr[hdr->e_shstrndx].sh_type != SHT_STRTAB) {
266 		printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
267 		    "_obj_loadimage: file has no section names\n");
268 		goto out;
269 	}
270 	ef->shstrindex = hdr->e_shstrndx;
271 	lastaddr = roundup(lastaddr, shdr[ef->shstrindex].sh_addralign);
272 	shdr[ef->shstrindex].sh_addr = (Elf_Addr)lastaddr;
273 	lastaddr += shdr[ef->shstrindex].sh_size;
274 
275 	/* Relocation tables. */
276 	for (i = 0; i < hdr->e_shnum; i++) {
277 		switch (shdr[i].sh_type) {
278 		case SHT_REL:
279 		case SHT_RELA:
280 			lastaddr = roundup(lastaddr, shdr[i].sh_addralign);
281 			shdr[i].sh_addr = (Elf_Addr)lastaddr;
282 			lastaddr += shdr[i].sh_size;
283 			break;
284 		}
285 	}
286 
287 	/* Clear the whole area, including bss regions. */
288 	kern_bzero(firstaddr, lastaddr - firstaddr);
289 
290 	/* Figure section with the lowest file offset we haven't loaded yet. */
291 	for (cshdr = NULL; /* none */; /* none */)
292 	{
293 		/*
294 		 * Find next section to load. The complexity of this loop is
295 		 * O(n^2), but with  the number of sections being typically
296 		 * small, we do not care.
297 		 */
298 		lshdr = cshdr;
299 
300 		for (i = 0; i < hdr->e_shnum; i++) {
301 			if (shdr[i].sh_addr == 0 ||
302 			    shdr[i].sh_type == SHT_NOBITS)
303 				continue;
304 			/* Skip sections that were loaded already. */
305 			if (lshdr != NULL &&
306 			    lshdr->sh_offset >= shdr[i].sh_offset)
307 				continue;
308 			/* Find section with smallest offset. */
309 			if (cshdr == lshdr ||
310 			    cshdr->sh_offset > shdr[i].sh_offset)
311 				cshdr = &shdr[i];
312 		}
313 
314 		if (cshdr == lshdr)
315 			break;
316 
317 		if (kern_pread(ef->fd, (vm_offset_t)cshdr->sh_addr,
318 		    cshdr->sh_size, (off_t)cshdr->sh_offset) != 0) {
319 			printf("\nelf" __XSTRING(__ELF_WORD_SIZE)
320 			    "_obj_loadimage: read failed\n");
321 			goto out;
322 		}
323 	}
324 
325 	file_addmetadata(fp, MODINFOMD_SHDR, shdrbytes, shdr);
326 
327 	res = __elfN(obj_parse_modmetadata)(fp, ef);
328 	if (res != 0)
329 		goto out;
330 
331 	ret = lastaddr - firstaddr;
332 	fp->f_addr = firstaddr;
333 
334 	printf("size 0x%lx at 0x%lx", (u_long)ret, (u_long)firstaddr);
335 
336 out:
337 	printf("\n");
338 	return ret;
339 }
340 
341 #if defined(__i386__) && __ELF_WORD_SIZE == 64
342 struct mod_metadata64 {
343 	int		md_version;	/* structure version MDTV_* */
344 	int		md_type;	/* type of entry MDT_* */
345 	u_int64_t	md_data;	/* specific data */
346 	u_int64_t	md_cval;	/* common string label */
347 };
348 #endif
349 
350 int
__elfN(obj_parse_modmetadata)351 __elfN(obj_parse_modmetadata)(struct preloaded_file *fp, elf_file_t ef)
352 {
353 	struct mod_metadata md;
354 #if defined(__i386__) && __ELF_WORD_SIZE == 64
355 	struct mod_metadata64 md64;
356 #endif
357 	struct mod_depend *mdepend;
358 	struct mod_version mver;
359 	char *s;
360 	int error, modcnt, minfolen;
361 	Elf_Addr v, p, p_stop;
362 
363 	if (__elfN(obj_lookup_set)(fp, ef, "modmetadata_set", &p, &p_stop,
364 	    &modcnt) != 0)
365 		return 0;
366 
367 	modcnt = 0;
368 	while (p < p_stop) {
369 		COPYOUT(p, &v, sizeof(v));
370 		error = __elfN(obj_reloc_ptr)(fp, ef, p, &v, sizeof(v));
371 		if (error != 0)
372 			return (error);
373 #if defined(__i386__) && __ELF_WORD_SIZE == 64
374 		COPYOUT(v, &md64, sizeof(md64));
375 		error = __elfN(obj_reloc_ptr)(fp, ef, v, &md64, sizeof(md64));
376 		if (error != 0)
377 			return (error);
378 		md.md_version = md64.md_version;
379 		md.md_type = md64.md_type;
380 		md.md_cval = (const char *)(uintptr_t)md64.md_cval;
381 		md.md_data = (void *)(uintptr_t)md64.md_data;
382 #else
383 		COPYOUT(v, &md, sizeof(md));
384 		error = __elfN(obj_reloc_ptr)(fp, ef, v, &md, sizeof(md));
385 		if (error != 0)
386 			return (error);
387 #endif
388 		p += sizeof(Elf_Addr);
389 		switch(md.md_type) {
390 		case MDT_DEPEND:
391 			s = strdupout((vm_offset_t)md.md_cval);
392 			minfolen = sizeof(*mdepend) + strlen(s) + 1;
393 			mdepend = malloc(minfolen);
394 			if (mdepend == NULL)
395 				return ENOMEM;
396 			COPYOUT((vm_offset_t)md.md_data, mdepend,
397 			    sizeof(*mdepend));
398 			strcpy((char*)(mdepend + 1), s);
399 			free(s);
400 			file_addmetadata(fp, MODINFOMD_DEPLIST, minfolen,
401 			    mdepend);
402 			free(mdepend);
403 			break;
404 		case MDT_VERSION:
405 			s = strdupout((vm_offset_t)md.md_cval);
406 			COPYOUT((vm_offset_t)md.md_data, &mver, sizeof(mver));
407 			file_addmodule(fp, s, mver.mv_version, NULL);
408 			free(s);
409 			modcnt++;
410 			break;
411 		case MDT_MODULE:
412 		case MDT_PNP_INFO:
413 			break;
414 		default:
415 			printf("unknown type %d\n", md.md_type);
416 			break;
417 		}
418 	}
419 	return 0;
420 }
421 
422 static int
__elfN(obj_lookup_set)423 __elfN(obj_lookup_set)(struct preloaded_file *fp __unused, elf_file_t ef,
424     const char* name, Elf_Addr *startp, Elf_Addr *stopp, int *countp)
425 {
426 	Elf_Ehdr *hdr;
427 	Elf_Shdr *shdr;
428 	char *p;
429 	vm_offset_t shstrtab;
430 	int i;
431 
432 	hdr = &ef->hdr;
433 	shdr = ef->e_shdr;
434 	shstrtab = shdr[ef->shstrindex].sh_addr;
435 
436 	for (i = 0; i < hdr->e_shnum; i++) {
437 		if (shdr[i].sh_type != SHT_PROGBITS)
438 			continue;
439 		if (shdr[i].sh_name == 0)
440 			continue;
441 		p = strdupout(shstrtab + shdr[i].sh_name);
442 		if (strncmp(p, "set_", 4) == 0 && strcmp(p + 4, name) == 0) {
443 			*startp = shdr[i].sh_addr;
444 			*stopp = shdr[i].sh_addr +  shdr[i].sh_size;
445 			*countp = (*stopp - *startp) / sizeof(Elf_Addr);
446 			free(p);
447 			return (0);
448 		}
449 		free(p);
450 	}
451 
452 	return (ESRCH);
453 }
454 
455 /*
456  * Apply any intra-module relocations to the value. p is the load address
457  * of the value and val/len is the value to be modified. This does NOT modify
458  * the image in-place, because this is done by kern_linker later on.
459  */
460 static int
__elfN(obj_reloc_ptr)461 __elfN(obj_reloc_ptr)(struct preloaded_file *mp, elf_file_t ef, Elf_Addr p,
462     void *val, size_t len)
463 {
464 	Elf_Ehdr *hdr;
465 	Elf_Shdr *shdr;
466 	Elf_Addr off = p;
467 	Elf_Addr base;
468 	Elf_Rela a, *abase;
469 	Elf_Rel r, *rbase;
470 	int error, i, j, nrel, nrela;
471 
472 	(void)mp;
473 	hdr = &ef->hdr;
474 	shdr = ef->e_shdr;
475 
476 	for (i = 0; i < hdr->e_shnum; i++) {
477 		if (shdr[i].sh_type != SHT_RELA && shdr[i].sh_type != SHT_REL)
478 			continue;
479 		base = shdr[shdr[i].sh_info].sh_addr;
480 		if (base == 0 || shdr[i].sh_addr == 0)
481 			continue;
482 		if (off < base || off + len > base +
483 		    shdr[shdr[i].sh_info].sh_size)
484 			continue;
485 
486 		switch (shdr[i].sh_type) {
487 		case SHT_RELA:
488 			abase = (Elf_Rela *)(intptr_t)shdr[i].sh_addr;
489 
490 			nrela = shdr[i].sh_size / sizeof(Elf_Rela);
491 			for (j = 0; j < nrela; j++) {
492 				COPYOUT(abase + j, &a, sizeof(a));
493 
494 				error = __elfN(reloc)(ef, __elfN(obj_symaddr),
495 				    &a, ELF_RELOC_RELA, base, off, val, len);
496 				if (error != 0)
497 					return (error);
498 			}
499 			break;
500 		case SHT_REL:
501 			rbase = (Elf_Rel *)(intptr_t)shdr[i].sh_addr;
502 
503 			nrel = shdr[i].sh_size / sizeof(Elf_Rel);
504 			for (j = 0; j < nrel; j++) {
505 				COPYOUT(rbase + j, &r, sizeof(r));
506 
507 				error = __elfN(reloc)(ef, __elfN(obj_symaddr),
508 				    &r, ELF_RELOC_REL, base, off, val, len);
509 				if (error != 0)
510 					return (error);
511 			}
512 			break;
513 		}
514 	}
515 	return (0);
516 }
517 
518 /* Look up the address of a specified symbol. */
519 static Elf_Addr
__elfN(obj_symaddr)520 __elfN(obj_symaddr)(struct elf_file *ef, Elf_Size symidx)
521 {
522 	Elf_Sym sym;
523 	Elf_Addr base;
524 
525 	if (symidx >= ef->e_shdr[ef->symtabindex].sh_size / sizeof(Elf_Sym))
526 		return (0);
527 	COPYOUT(ef->e_shdr[ef->symtabindex].sh_addr + symidx * sizeof(Elf_Sym),
528 	    &sym, sizeof(sym));
529 	if (sym.st_shndx == SHN_UNDEF || sym.st_shndx >= ef->hdr.e_shnum)
530 		return (0);
531 	base = ef->e_shdr[sym.st_shndx].sh_addr;
532 	if (base == 0)
533 		return (0);
534 	return (base + sym.st_value);
535 }
536