exec_elf32.c revision 1.4 
1/*	$NetBSD: exec_elf32.c,v 1.4 1996/01/16 23:07:18 fvdl Exp $	*/
2
3/*
4 * Copyright (c) 1994 Christos Zoulas
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 * 3. The name of the author may not be used to endorse or promote products
16 *    derived from this software without specific prior written permission
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 */
30
31#include <sys/param.h>
32#include <sys/systm.h>
33#include <sys/kernel.h>
34#include <sys/proc.h>
35#include <sys/malloc.h>
36#include <sys/namei.h>
37#include <sys/vnode.h>
38#include <sys/exec.h>
39#include <sys/exec_elf.h>
40
41#include <sys/mman.h>
42#include <vm/vm.h>
43#include <vm/vm_param.h>
44#include <vm/vm_map.h>
45
46#include <machine/cpu.h>
47#include <machine/reg.h>
48#include <machine/exec.h>
49
50#ifdef COMPAT_LINUX
51#include <compat/linux/linux_exec.h>
52#endif
53
54#ifdef COMPAT_SVR4
55#include <compat/svr4/svr4_exec.h>
56#endif
57
58int (*elf_probe_funcs[])() = {
59#ifdef COMPAT_SVR4
60	svr4_elf_probe,
61#endif
62#ifdef COMPAT_LINUX
63	linux_elf_probe
64#endif
65};
66
67static int elf_read_from __P((struct proc *, struct vnode *, u_long,
68	caddr_t, int));
69static void elf_load_psection __P((struct exec_vmcmd_set *,
70	struct vnode *, Elf32_Phdr *, u_long *, u_long *, int *));
71
72#define ELF_ALIGN(a, b) ((a) & ~((b) - 1))
73
74/*
75 * Copy arguments onto the stack in the normal way, but add some
76 * extra information in case of dynamic binding.
77 */
78void *
79elf_copyargs(pack, arginfo, stack, argp)
80	struct exec_package *pack;
81	struct ps_strings *arginfo;
82	void *stack;
83	void *argp;
84{
85	size_t len;
86	AuxInfo ai[ELF_AUX_ENTRIES], *a;
87	struct elf_args *ap;
88
89	stack = copyargs(pack, arginfo, stack, argp);
90	if (!stack)
91		return NULL;
92
93	/*
94	 * Push extra arguments on the stack needed by dynamically
95	 * linked binaries
96	 */
97	if ((ap = (struct elf_args *) pack->ep_emul_arg)) {
98		a = ai;
99
100		a->au_id = AUX_phdr;
101		a->au_v = ap->arg_phaddr;
102		a++;
103
104		a->au_id = AUX_phent;
105		a->au_v = ap->arg_phentsize;
106		a++;
107
108		a->au_id = AUX_phnum;
109		a->au_v = ap->arg_phnum;
110		a++;
111
112		a->au_id = AUX_pagesz;
113		a->au_v = NBPG;
114		a++;
115
116		a->au_id = AUX_base;
117		a->au_v = ap->arg_interp;
118		a++;
119
120		a->au_id = AUX_flags;
121		a->au_v = 0;
122		a++;
123
124		a->au_id = AUX_entry;
125		a->au_v = ap->arg_entry;
126		a++;
127
128		a->au_id = AUX_null;
129		a->au_v = 0;
130		a++;
131
132		free((char *) ap, M_TEMP);
133		len = ELF_AUX_ENTRIES * sizeof (AuxInfo);
134		if (copyout(ai, stack, len))
135			return NULL;
136		stack += len;
137	}
138	return stack;
139}
140
141/*
142 * elf_check_header():
143 *
144 * Check header for validity; return 0 of ok ENOEXEC if error
145 *
146 * XXX machine type needs to be moved to <machine/param.h> so
147 * just one comparison can be done. Unfortunately, there is both
148 * em_486 and em_386, so this would not work on the i386.
149 */
150int
151elf_check_header(eh, type)
152	Elf32_Ehdr *eh;
153	int type;
154{
155
156	if (bcmp(eh->e_ident, Elf32_e_ident, Elf32_e_siz) != 0)
157		return ENOEXEC;
158
159	switch (eh->e_machine) {
160	/* XXX */
161#ifdef i386
162	case Elf32_em_386:
163	case Elf32_em_486:
164#endif
165#ifdef sparc
166	case Elf32_em_sparc:
167#endif
168		break;
169
170	default:
171		return ENOEXEC;
172	}
173
174	if (eh->e_type != type)
175		return ENOEXEC;
176
177	return 0;
178}
179
180/*
181 * elf_load_psection():
182 *
183 * Load a psection at the appropriate address
184 */
185static void
186elf_load_psection(vcset, vp, ph, addr, size, prot)
187	struct exec_vmcmd_set *vcset;
188	struct vnode *vp;
189	Elf32_Phdr *ph;
190	u_long *addr;
191	u_long *size;
192	int *prot;
193{
194	u_long uaddr, msize, rm, rf;
195	long diff, offset;
196
197	/*
198         * If the user specified an address, then we load there.
199         */
200	if (*addr != ELF32_NO_ADDR) {
201		if (ph->p_align > 1) {
202			*addr = ELF_ALIGN(*addr + ph->p_align, ph->p_align);
203			uaddr = ELF_ALIGN(ph->p_vaddr, ph->p_align);
204		} else
205			uaddr = ph->p_vaddr;
206		diff = ph->p_vaddr - uaddr;
207	} else {
208		*addr = uaddr = ph->p_vaddr;
209		if (ph->p_align > 1)
210			*addr = ELF_ALIGN(uaddr, ph->p_align);
211		diff = uaddr - *addr;
212	}
213
214	*prot |= (ph->p_flags & Elf32_pf_r) ? VM_PROT_READ : 0;
215	*prot |= (ph->p_flags & Elf32_pf_w) ? VM_PROT_WRITE : 0;
216	*prot |= (ph->p_flags & Elf32_pf_x) ? VM_PROT_EXECUTE : 0;
217
218	offset = ph->p_offset - diff;
219	*size = ph->p_filesz + diff;
220	msize = ph->p_memsz + diff;
221
222	NEW_VMCMD(vcset, vmcmd_map_readvn, *size, *addr, vp, offset, *prot);
223
224	/*
225         * Check if we need to extend the size of the segment
226         */
227	rm = round_page(*addr + msize);
228	rf = round_page(*addr + *size);
229
230	if (rm != rf) {
231		NEW_VMCMD(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP, 0, *prot);
232		*size = msize;
233	}
234}
235
236/*
237 * elf_read_from():
238 *
239 *	Read from vnode into buffer at offset.
240 */
241static int
242elf_read_from(p, vp, off, buf, size)
243	struct vnode *vp;
244	u_long off;
245	struct proc *p;
246	caddr_t buf;
247	int size;
248{
249	int error;
250	int resid;
251
252	if ((error = vn_rdwr(UIO_READ, vp, buf, size,
253			     off, UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred,
254			     &resid, p)) != 0)
255		return error;
256	/*
257         * See if we got all of it
258         */
259	if (resid != 0)
260		return ENOEXEC;
261	return 0;
262}
263
264/*
265 * elf_load_file():
266 *
267 * Load a file (interpreter/library) pointed to by path
268 * [stolen from coff_load_shlib()]. Made slightly generic
269 * so it might be used externally.
270 */
271int
272elf_load_file(p, path, vcset, entry, ap, last)
273	struct proc *p;
274	char *path;
275	struct exec_vmcmd_set *vcset;
276	u_long *entry;
277	struct elf_args	*ap;
278	u_long *last;
279{
280	int error, i;
281	struct nameidata nd;
282	Elf32_Ehdr eh;
283	Elf32_Phdr *ph = NULL;
284	u_long phsize;
285	char *bp = NULL;
286	u_long addr = *last;
287
288	bp = path;
289	/*
290         * 1. open file
291         * 2. read filehdr
292         * 3. map text, data, and bss out of it using VM_*
293         */
294	NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, path, p);
295	if ((error = namei(&nd)) != 0) {
296		return error;
297	}
298	if ((error = elf_read_from(p, nd.ni_vp, 0, (caddr_t) &eh,
299				    sizeof(eh))) != 0)
300		goto bad;
301
302	if ((error = elf_check_header(&eh, Elf32_et_dyn)) != 0)
303		goto bad;
304
305	phsize = eh.e_phnum * sizeof(Elf32_Phdr);
306	ph = (Elf32_Phdr *) malloc(phsize, M_TEMP, M_WAITOK);
307
308	if ((error = elf_read_from(p, nd.ni_vp, eh.e_phoff,
309				    (caddr_t) ph, phsize)) != 0)
310		goto bad;
311
312	/*
313         * Load all the necessary sections
314         */
315	for (i = 0; i < eh.e_phnum; i++) {
316		u_long size = 0;
317		int prot = 0;
318
319		switch (ph[i].p_type) {
320		case Elf32_pt_load:
321			elf_load_psection(vcset, nd.ni_vp, &ph[i], &addr,
322						&size, &prot);
323			/* If entry is within this section it must be text */
324			if (eh.e_entry >= ph[i].p_vaddr &&
325			    eh.e_entry < (ph[i].p_vaddr + size)) {
326				*entry = addr + eh.e_entry;
327				ap->arg_interp = addr;
328			}
329			addr += size;
330			break;
331
332		case Elf32_pt_dynamic:
333		case Elf32_pt_phdr:
334		case Elf32_pt_note:
335			break;
336
337		default:
338			break;
339		}
340	}
341
342bad:
343	if (ph != NULL)
344		free((char *) ph, M_TEMP);
345
346	*last = addr;
347	vrele(nd.ni_vp);
348	return error;
349}
350
351/*
352 * exec_elf_makecmds(): Prepare an Elf binary's exec package
353 *
354 * First, set of the various offsets/lengths in the exec package.
355 *
356 * Then, mark the text image busy (so it can be demand paged) or error
357 * out if this is not possible.  Finally, set up vmcmds for the
358 * text, data, bss, and stack segments.
359 *
360 * XXX no demand paging (yet?)
361 */
362int
363exec_elf_makecmds(p, epp)
364	struct proc *p;
365	struct exec_package *epp;
366{
367	Elf32_Ehdr *eh = epp->ep_hdr;
368	Elf32_Phdr *ph, *pp;
369	Elf32_Addr phdr = 0;
370	int error, i, n, nload;
371	char interp[MAXPATHLEN];
372	u_long pos = 0, phsize;
373
374	if (epp->ep_hdrvalid < sizeof(Elf32_Ehdr))
375		return ENOEXEC;
376
377	if (elf_check_header(eh, Elf32_et_exec))
378		return ENOEXEC;
379
380	/*
381         * check if vnode is in open for writing, because we want to
382         * demand-page out of it.  if it is, don't do it, for various
383         * reasons
384         */
385	if (epp->ep_vp->v_writecount != 0) {
386#ifdef DIAGNOSTIC
387		if (epp->ep_vp->v_flag & VTEXT)
388			panic("exec: a VTEXT vnode has writecount != 0\n");
389#endif
390		return ETXTBSY;
391	}
392	/*
393         * Allocate space to hold all the program headers, and read them
394         * from the file
395         */
396	phsize = eh->e_phnum * sizeof(Elf32_Phdr);
397	ph = (Elf32_Phdr *) malloc(phsize, M_TEMP, M_WAITOK);
398
399	if ((error = elf_read_from(p, epp->ep_vp, eh->e_phoff,
400				    (caddr_t) ph, phsize)) != 0)
401		goto bad;
402
403	epp->ep_tsize = ELF32_NO_ADDR;
404	epp->ep_dsize = ELF32_NO_ADDR;
405
406	interp[0] = '\0';
407
408	for (i = 0; i < eh->e_phnum; i++) {
409		pp = &ph[i];
410		if (pp->p_type == Elf32_pt_interp) {
411			if (pp->p_filesz >= sizeof(interp))
412				goto bad;
413			if ((error = elf_read_from(p, epp->ep_vp, pp->p_offset,
414				      (caddr_t) interp, pp->p_filesz)) != 0)
415				goto bad;
416			break;
417		}
418	}
419
420	/*
421	 * On the same architecture, we may be emulating different systems.
422	 * See which one will accept this executable. This currently only
423	 * applies to Linux and SVR4 on the i386.
424	 *
425	 * Probe functions would normally see if the interpreter (if any)
426	 * exists. Emulation packages may possibly replace the interpreter in
427	 * interp[] with a changed path (/emul/xxx/<path>), and also
428	 * set the ep_emul field in the exec package structure.
429	 */
430	if ((n = sizeof elf_probe_funcs / sizeof elf_probe_funcs[0])) {
431		error = ENOEXEC;
432		for (i = 0; i < n && error; i++)
433			error = elf_probe_funcs[i](p, epp, interp, &pos);
434
435		if (error)
436			goto bad;
437	}
438
439	/*
440         * Load all the necessary sections
441         */
442	for (i = nload = 0; i < eh->e_phnum; i++) {
443		u_long  addr = ELF32_NO_ADDR, size = 0;
444		int prot = 0;
445
446		pp = &ph[i];
447
448		switch (ph[i].p_type) {
449		case Elf32_pt_load:
450			/*
451			 * XXX
452			 * Can handle only 2 sections: text and data
453			 */
454			if (nload++ == 2)
455				goto bad;
456			elf_load_psection(&epp->ep_vmcmds, epp->ep_vp,
457				&ph[i], &addr, &size, &prot);
458			/*
459			 * Decide whether it's text or data by looking
460			 * at the entry point.
461			 */
462			if (eh->e_entry >= addr && eh->e_entry < (addr + size)){
463				epp->ep_taddr = addr;
464				epp->ep_tsize = size;
465			} else {
466				epp->ep_daddr = addr;
467				epp->ep_dsize = size;
468			}
469			break;
470
471		case Elf32_pt_shlib:
472			error = ENOEXEC;
473			goto bad;
474
475		case Elf32_pt_interp:
476			/* Already did this one */
477		case Elf32_pt_dynamic:
478		case Elf32_pt_note:
479			break;
480
481		case Elf32_pt_phdr:
482			/* Note address of program headers (in text segment) */
483			phdr = pp->p_vaddr;
484		break;
485
486		default:
487			/*
488			 * Not fatal, we don't need to understand everything
489			 * :-)
490			 */
491			break;
492		}
493	}
494
495	/*
496         * Check if we found a dynamically linked binary and arrange to load
497         * it's interpreter
498         */
499	if (interp[0]) {
500		struct elf_args *ap;
501
502		ap = (struct elf_args *) malloc(sizeof(struct elf_args),
503						 M_TEMP, M_WAITOK);
504		if ((error = elf_load_file(p, interp, &epp->ep_vmcmds,
505				&epp->ep_entry, ap, &pos)) != 0) {
506			free((char *) ap, M_TEMP);
507			goto bad;
508		}
509		pos += phsize;
510		ap->arg_phaddr = phdr;
511
512		ap->arg_phentsize = eh->e_phentsize;
513		ap->arg_phnum = eh->e_phnum;
514		ap->arg_entry = eh->e_entry;
515
516		epp->ep_emul_arg = ap;
517	} else
518		epp->ep_entry = eh->e_entry;
519
520	free((char *) ph, M_TEMP);
521	epp->ep_vp->v_flag |= VTEXT;
522	return exec_aout_setup_stack(p, epp);
523
524bad:
525	free((char *) ph, M_TEMP);
526	kill_vmcmds(&epp->ep_vmcmds);
527	return ENOEXEC;
528}
529