1/* $NetBSD: exec_elf.c,v 1.87 2016/09/15 18:40:34 christos Exp $ */
2
3/*-
4 * Copyright (c) 1994, 2000, 2005, 2015 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Christos Zoulas and Maxime Villard.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32/*
33 * Copyright (c) 1996 Christopher G. Demetriou
34 * All rights reserved.
35 *
36 * Redistribution and use in source and binary forms, with or without
37 * modification, are permitted provided that the following conditions
38 * are met:
39 * 1. Redistributions of source code must retain the above copyright
40 * notice, this list of conditions and the following disclaimer.
41 * 2. Redistributions in binary form must reproduce the above copyright
42 * notice, this list of conditions and the following disclaimer in the
43 * documentation and/or other materials provided with the distribution.
44 * 3. The name of the author may not be used to endorse or promote products
45 * derived from this software without specific prior written permission
46 *
47 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
48 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
49 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
50 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
51 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
52 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
53 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
54 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
55 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
56 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
57 */
58
59#include <sys/cdefs.h>
60__KERNEL_RCSID(1, "$NetBSD: exec_elf.c,v 1.87 2016/09/15 18:40:34 christos Exp $");
61
62#ifdef _KERNEL_OPT
63#include "opt_pax.h"
64#endif /* _KERNEL_OPT */
65
66#include <sys/param.h>
67#include <sys/proc.h>
68#include <sys/kmem.h>
69#include <sys/namei.h>
70#include <sys/vnode.h>
71#include <sys/exec.h>
72#include <sys/exec_elf.h>
73#include <sys/syscall.h>
74#include <sys/signalvar.h>
75#include <sys/mount.h>
76#include <sys/stat.h>
77#include <sys/kauth.h>
78#include <sys/bitops.h>
79
80#include <sys/cpu.h>
81#include <machine/reg.h>
82
83#include <compat/common/compat_util.h>
84
85#include <sys/pax.h>
86#include <uvm/uvm_param.h>
87
88extern struct emul emul_netbsd;
89
90#define elf_check_header ELFNAME(check_header)
91#define elf_copyargs ELFNAME(copyargs)
92#define elf_load_interp ELFNAME(load_interp)
93#define elf_load_psection ELFNAME(load_psection)
94#define exec_elf_makecmds ELFNAME2(exec,makecmds)
95#define netbsd_elf_signature ELFNAME2(netbsd,signature)
96#define netbsd_elf_probe ELFNAME2(netbsd,probe)
97#define coredump ELFNAMEEND(coredump)
98#define elf_free_emul_arg ELFNAME(free_emul_arg)
99
100static int
101elf_load_interp(struct lwp *, struct exec_package *, char *,
102 struct exec_vmcmd_set *, u_long *, Elf_Addr *);
103static void
104elf_load_psection(struct exec_vmcmd_set *, struct vnode *, const Elf_Phdr *,
105 Elf_Addr *, u_long *, int);
106
107int netbsd_elf_signature(struct lwp *, struct exec_package *, Elf_Ehdr *);
108int netbsd_elf_probe(struct lwp *, struct exec_package *, void *, char *,
109 vaddr_t *);
110
111static void elf_free_emul_arg(void *);
112
113#ifdef DEBUG_ELF
114#define DPRINTF(a, ...) printf("%s: " a "\n", __func__, ##__VA_ARGS__)
115#else
116#define DPRINTF(a, ...)
117#endif
118
119/* round up and down to page boundaries. */
120#define ELF_ROUND(a, b) (((a) + (b) - 1) & ~((b) - 1))
121#define ELF_TRUNC(a, b) ((a) & ~((b) - 1))
122
123static void
124elf_placedynexec(struct exec_package *epp, Elf_Ehdr *eh, Elf_Phdr *ph)
125{
126 Elf_Addr align, offset;
127 int i;
128
129 for (align = i = 0; i < eh->e_phnum; i++)
130 if (ph[i].p_type == PT_LOAD && ph[i].p_align > align)
131 align = ph[i].p_align;
132
133 offset = (Elf_Addr)pax_aslr_exec_offset(epp, align);
134 offset += epp->ep_vm_minaddr;
135
136 for (i = 0; i < eh->e_phnum; i++)
137 ph[i].p_vaddr += offset;
138 epp->ep_entryoffset = offset;
139 eh->e_entry += offset;
140}
141
142/*
143 * Copy arguments onto the stack in the normal way, but add some
144 * extra information in case of dynamic binding.
145 */
146int
147elf_copyargs(struct lwp *l, struct exec_package *pack,
148 struct ps_strings *arginfo, char **stackp, void *argp)
149{
150 size_t len, vlen;
151 AuxInfo ai[ELF_AUX_ENTRIES], *a, *execname;
152 struct elf_args *ap;
153 int error;
154
155 if ((error = copyargs(l, pack, arginfo, stackp, argp)) != 0)
156 return error;
157
158 a = ai;
159 execname = NULL;
160
161 memset(ai, 0, sizeof(ai));
162
163 /*
164 * Push extra arguments on the stack needed by dynamically
165 * linked binaries
166 */
167 if ((ap = (struct elf_args *)pack->ep_emul_arg)) {
168 struct vattr *vap = pack->ep_vap;
169
170 a->a_type = AT_PHDR;
171 a->a_v = ap->arg_phaddr;
172 a++;
173
174 a->a_type = AT_PHENT;
175 a->a_v = ap->arg_phentsize;
176 a++;
177
178 a->a_type = AT_PHNUM;
179 a->a_v = ap->arg_phnum;
180 a++;
181
182 a->a_type = AT_PAGESZ;
183 a->a_v = PAGE_SIZE;
184 a++;
185
186 a->a_type = AT_BASE;
187 a->a_v = ap->arg_interp;
188 a++;
189
190 a->a_type = AT_FLAGS;
191 a->a_v = 0;
192 a++;
193
194 a->a_type = AT_ENTRY;
195 a->a_v = ap->arg_entry;
196 a++;
197
198 a->a_type = AT_EUID;
199 if (vap->va_mode & S_ISUID)
200 a->a_v = vap->va_uid;
201 else
202 a->a_v = kauth_cred_geteuid(l->l_cred);
203 a++;
204
205 a->a_type = AT_RUID;
206 a->a_v = kauth_cred_getuid(l->l_cred);
207 a++;
208
209 a->a_type = AT_EGID;
210 if (vap->va_mode & S_ISGID)
211 a->a_v = vap->va_gid;
212 else
213 a->a_v = kauth_cred_getegid(l->l_cred);
214 a++;
215
216 a->a_type = AT_RGID;
217 a->a_v = kauth_cred_getgid(l->l_cred);
218 a++;
219
220 a->a_type = AT_STACKBASE;
221 a->a_v = l->l_proc->p_stackbase;
222 a++;
223
224 if (pack->ep_path) {
225 execname = a;
226 a->a_type = AT_SUN_EXECNAME;
227 a++;
228 }
229
230 exec_free_emul_arg(pack);
231 }
232
233 a->a_type = AT_NULL;
234 a->a_v = 0;
235 a++;
236
237 vlen = (a - ai) * sizeof(ai[0]);
238
239 KASSERT(vlen <= sizeof(ai));
240
241 if (execname) {
242 char *path = pack->ep_path;
243 execname->a_v = (uintptr_t)(*stackp + vlen);
244 len = strlen(path) + 1;
245 if ((error = copyout(path, (*stackp + vlen), len)) != 0)
246 return error;
247 len = ALIGN(len);
248 } else
249 len = 0;
250
251 if ((error = copyout(ai, *stackp, vlen)) != 0)
252 return error;
253 *stackp += vlen + len;
254
255 return 0;
256}
257
258/*
259 * elf_check_header():
260 *
261 * Check header for validity; return 0 if ok, ENOEXEC if error
262 */
263int
264elf_check_header(Elf_Ehdr *eh)
265{
266
267 if (memcmp(eh->e_ident, ELFMAG, SELFMAG) != 0 ||
268 eh->e_ident[EI_CLASS] != ELFCLASS) {
269 DPRINTF("bad magic %#x%x%x", eh->e_ident[0], eh->e_ident[1],
270 eh->e_ident[2]);
271 return ENOEXEC;
272 }
273
274 switch (eh->e_machine) {
275
276 ELFDEFNNAME(MACHDEP_ID_CASES)
277
278 default:
279 DPRINTF("bad machine %#x", eh->e_machine);
280 return ENOEXEC;
281 }
282
283 if (ELF_EHDR_FLAGS_OK(eh) == 0) {
284 DPRINTF("bad flags %#x", eh->e_flags);
285 return ENOEXEC;
286 }
287
288 if (eh->e_shnum > ELF_MAXSHNUM || eh->e_phnum > ELF_MAXPHNUM) {
289 DPRINTF("bad shnum/phnum %#x/%#x", eh->e_shnum, eh->e_phnum);
290 return ENOEXEC;
291 }
292
293 return 0;
294}
295
296/*
297 * elf_load_psection():
298 *
299 * Load a psection at the appropriate address
300 */
301static void
302elf_load_psection(struct exec_vmcmd_set *vcset, struct vnode *vp,
303 const Elf_Phdr *ph, Elf_Addr *addr, u_long *size, int flags)
304{
305 u_long msize, psize, rm, rf;
306 long diff, offset;
307 int vmprot = 0;
308
309 /*
310 * If the user specified an address, then we load there.
311 */
312 if (*addr == ELFDEFNNAME(NO_ADDR))
313 *addr = ph->p_vaddr;
314
315 if (ph->p_align > 1) {
316 /*
317 * Make sure we are virtually aligned as we are supposed to be.
318 */
319 diff = ph->p_vaddr - ELF_TRUNC(ph->p_vaddr, ph->p_align);
320 KASSERT(*addr - diff == ELF_TRUNC(*addr, ph->p_align));
321 /*
322 * But make sure to not map any pages before the start of the
323 * psection by limiting the difference to within a page.
324 */
325 diff &= PAGE_MASK;
326 } else
327 diff = 0;
328
329 vmprot |= (ph->p_flags & PF_R) ? VM_PROT_READ : 0;
330 vmprot |= (ph->p_flags & PF_W) ? VM_PROT_WRITE : 0;
331 vmprot |= (ph->p_flags & PF_X) ? VM_PROT_EXECUTE : 0;
332
333 /*
334 * Adjust everything so it all starts on a page boundary.
335 */
336 *addr -= diff;
337 offset = ph->p_offset - diff;
338 *size = ph->p_filesz + diff;
339 msize = ph->p_memsz + diff;
340
341 if (ph->p_align >= PAGE_SIZE) {
342 if ((ph->p_flags & PF_W) != 0) {
343 /*
344 * Because the pagedvn pager can't handle zero fill
345 * of the last data page if it's not page aligned we
346 * map the last page readvn.
347 */
348 psize = trunc_page(*size);
349 } else {
350 psize = round_page(*size);
351 }
352 } else {
353 psize = *size;
354 }
355
356 if (psize > 0) {
357 NEW_VMCMD2(vcset, ph->p_align < PAGE_SIZE ?
358 vmcmd_map_readvn : vmcmd_map_pagedvn, psize, *addr, vp,
359 offset, vmprot, flags);
360 flags &= VMCMD_RELATIVE;
361 }
362 if (psize < *size) {
363 NEW_VMCMD2(vcset, vmcmd_map_readvn, *size - psize,
364 *addr + psize, vp, offset + psize, vmprot, flags);
365 }
366
367 /*
368 * Check if we need to extend the size of the segment (does
369 * bss extend page the next page boundary)?
370 */
371 rm = round_page(*addr + msize);
372 rf = round_page(*addr + *size);
373
374 if (rm != rf) {
375 NEW_VMCMD2(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP,
376 0, vmprot, flags & VMCMD_RELATIVE);
377 *size = msize;
378 }
379}
380
381/*
382 * elf_load_interp():
383 *
384 * Load an interpreter pointed to by path.
385 */
386static int
387elf_load_interp(struct lwp *l, struct exec_package *epp, char *path,
388 struct exec_vmcmd_set *vcset, u_long *entryoff, Elf_Addr *last)
389{
390 int error, i;
391 struct vnode *vp;
392 struct vattr attr;
393 Elf_Ehdr eh;
394 Elf_Phdr *ph = NULL;
395 const Elf_Phdr *base_ph;
396 const Elf_Phdr *last_ph;
397 u_long phsize;
398 Elf_Addr addr = *last;
399 struct proc *p;
400 bool use_topdown;
401
402 p = l->l_proc;
403
404 KASSERT(p->p_vmspace);
405 KASSERT(p->p_vmspace != proc0.p_vmspace);
406
407#ifdef __USE_TOPDOWN_VM
408 use_topdown = epp->ep_flags & EXEC_TOPDOWN_VM;
409#else
410 use_topdown = false;
411#endif
412
413 /*
414 * 1. open file
415 * 2. read filehdr
416 * 3. map text, data, and bss out of it using VM_*
417 */
418 vp = epp->ep_interp;
419 if (vp == NULL) {
420 error = emul_find_interp(l, epp, path);
421 if (error != 0)
422 return error;
423 vp = epp->ep_interp;
424 }
425 /* We'll tidy this ourselves - otherwise we have locking issues */
426 epp->ep_interp = NULL;
427 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
428
429 /*
430 * Similarly, if it's not marked as executable, or it's not a regular
431 * file, we don't allow it to be used.
432 */
433 if (vp->v_type != VREG) {
434 error = EACCES;
435 goto badunlock;
436 }
437 if ((error = VOP_ACCESS(vp, VEXEC, l->l_cred)) != 0)
438 goto badunlock;
439
440 /* get attributes */
441 if ((error = VOP_GETATTR(vp, &attr, l->l_cred)) != 0)
442 goto badunlock;
443
444 /*
445 * Check mount point. Though we're not trying to exec this binary,
446 * we will be executing code from it, so if the mount point
447 * disallows execution or set-id-ness, we punt or kill the set-id.
448 */
449 if (vp->v_mount->mnt_flag & MNT_NOEXEC) {
450 error = EACCES;
451 goto badunlock;
452 }
453 if (vp->v_mount->mnt_flag & MNT_NOSUID)
454 epp->ep_vap->va_mode &= ~(S_ISUID | S_ISGID);
455
456 error = vn_marktext(vp);
457 if (error)
458 goto badunlock;
459
460 VOP_UNLOCK(vp);
461
462 if ((error = exec_read_from(l, vp, 0, &eh, sizeof(eh))) != 0)
463 goto bad;
464
465 if ((error = elf_check_header(&eh)) != 0)
466 goto bad;
467 if (eh.e_type != ET_DYN || eh.e_phnum == 0) {
468 DPRINTF("bad interpreter type %#x", eh.e_type);
469 error = ENOEXEC;
470 goto bad;
471 }
472
473 phsize = eh.e_phnum * sizeof(Elf_Phdr);
474 ph = kmem_alloc(phsize, KM_SLEEP);
475
476 if ((error = exec_read_from(l, vp, eh.e_phoff, ph, phsize)) != 0)
477 goto bad;
478
479#ifdef ELF_INTERP_NON_RELOCATABLE
480 /*
481 * Evil hack: Only MIPS should be non-relocatable, and the
482 * psections should have a high address (typically 0x5ffe0000).
483 * If it's now relocatable, it should be linked at 0 and the
484 * psections should have zeros in the upper part of the address.
485 * Otherwise, force the load at the linked address.
486 */
487 if (*last == ELF_LINK_ADDR && (ph->p_vaddr & 0xffff0000) == 0)
488 *last = ELFDEFNNAME(NO_ADDR);
489#endif
490
491 /*
492 * If no position to load the interpreter was set by a probe
493 * function, pick the same address that a non-fixed mmap(0, ..)
494 * would (i.e. something safely out of the way).
495 */
496 if (*last == ELFDEFNNAME(NO_ADDR)) {
497 u_long limit = 0;
498 /*
499 * Find the start and ending addresses of the psections to
500 * be loaded. This will give us the size.
501 */
502 for (i = 0, base_ph = NULL; i < eh.e_phnum; i++) {
503 if (ph[i].p_type == PT_LOAD) {
504 u_long psize = ph[i].p_vaddr + ph[i].p_memsz;
505 if (base_ph == NULL)
506 base_ph = &ph[i];
507 if (psize > limit)
508 limit = psize;
509 }
510 }
511
512 if (base_ph == NULL) {
513 DPRINTF("no interpreter loadable sections");
514 error = ENOEXEC;
515 goto bad;
516 }
517
518 /*
519 * Now compute the size and load address.
520 */
521 addr = (*epp->ep_esch->es_emul->e_vm_default_addr)(p,
522 epp->ep_daddr,
523 round_page(limit) - trunc_page(base_ph->p_vaddr),
524 use_topdown);
525 addr += (Elf_Addr)pax_aslr_rtld_offset(epp, base_ph->p_align,
526 use_topdown);
527 } else {
528 addr = *last; /* may be ELF_LINK_ADDR */
529 }
530
531 /*
532 * Load all the necessary sections
533 */
534 for (i = 0, base_ph = NULL, last_ph = NULL; i < eh.e_phnum; i++) {
535 switch (ph[i].p_type) {
536 case PT_LOAD: {
537 u_long size;
538 int flags;
539
540 if (base_ph == NULL) {
541 /*
542 * First encountered psection is always the
543 * base psection. Make sure it's aligned
544 * properly (align down for topdown and align
545 * upwards for not topdown).
546 */
547 base_ph = &ph[i];
548 flags = VMCMD_BASE;
549 if (addr == ELF_LINK_ADDR)
550 addr = ph[i].p_vaddr;
551 if (use_topdown)
552 addr = ELF_TRUNC(addr, ph[i].p_align);
553 else
554 addr = ELF_ROUND(addr, ph[i].p_align);
555 } else {
556 u_long limit = round_page(last_ph->p_vaddr
557 + last_ph->p_memsz);
558 u_long base = trunc_page(ph[i].p_vaddr);
559
560 /*
561 * If there is a gap in between the psections,
562 * map it as inaccessible so nothing else
563 * mmap'ed will be placed there.
564 */
565 if (limit != base) {
566 NEW_VMCMD2(vcset, vmcmd_map_zero,
567 base - limit,
568 limit - base_ph->p_vaddr, NULLVP,
569 0, VM_PROT_NONE, VMCMD_RELATIVE);
570 }
571
572 addr = ph[i].p_vaddr - base_ph->p_vaddr;
573 flags = VMCMD_RELATIVE;
574 }
575 last_ph = &ph[i];
576 elf_load_psection(vcset, vp, &ph[i], &addr,
577 &size, flags);
578 /*
579 * If entry is within this psection then this
580 * must contain the .text section. *entryoff is
581 * relative to the base psection.
582 */
583 if (eh.e_entry >= ph[i].p_vaddr &&
584 eh.e_entry < (ph[i].p_vaddr + size)) {
585 *entryoff = eh.e_entry - base_ph->p_vaddr;
586 }
587 addr += size;
588 break;
589 }
590
591 default:
592 break;
593 }
594 }
595
596 kmem_free(ph, phsize);
597 /*
598 * This value is ignored if TOPDOWN.
599 */
600 *last = addr;
601 vrele(vp);
602 return 0;
603
604badunlock:
605 VOP_UNLOCK(vp);
606
607bad:
608 if (ph != NULL)
609 kmem_free(ph, phsize);
610 vrele(vp);
611 return error;
612}
613
614/*
615 * exec_elf_makecmds(): Prepare an Elf binary's exec package
616 *
617 * First, set of the various offsets/lengths in the exec package.
618 *
619 * Then, mark the text image busy (so it can be demand paged) or error
620 * out if this is not possible. Finally, set up vmcmds for the
621 * text, data, bss, and stack segments.
622 */
623int
624exec_elf_makecmds(struct lwp *l, struct exec_package *epp)
625{
626 Elf_Ehdr *eh = epp->ep_hdr;
627 Elf_Phdr *ph, *pp;
628 Elf_Addr phdr = 0, computed_phdr = 0, pos = 0, end_text = 0;
629 int error, i;
630 char *interp = NULL;
631 u_long phsize;
632 struct elf_args *ap;
633 bool is_dyn = false;
634
635 if (epp->ep_hdrvalid < sizeof(Elf_Ehdr)) {
636 DPRINTF("small header %#x", epp->ep_hdrvalid);
637 return ENOEXEC;
638 }
639 if ((error = elf_check_header(eh)) != 0)
640 return error;
641
642 if (eh->e_type == ET_DYN)
643 /* PIE, and some libs have an entry point */
644 is_dyn = true;
645 else if (eh->e_type != ET_EXEC) {
646 DPRINTF("bad type %#x", eh->e_type);
647 return ENOEXEC;
648 }
649
650 if (eh->e_phnum == 0) {
651 DPRINTF("no program headers");
652 return ENOEXEC;
653 }
654
655 error = vn_marktext(epp->ep_vp);
656 if (error)
657 return error;
658
659 /*
660 * Allocate space to hold all the program headers, and read them
661 * from the file
662 */
663 phsize = eh->e_phnum * sizeof(Elf_Phdr);
664 ph = kmem_alloc(phsize, KM_SLEEP);
665
666 if ((error = exec_read_from(l, epp->ep_vp, eh->e_phoff, ph, phsize)) !=
667 0)
668 goto bad;
669
670 epp->ep_taddr = epp->ep_tsize = ELFDEFNNAME(NO_ADDR);
671 epp->ep_daddr = epp->ep_dsize = ELFDEFNNAME(NO_ADDR);
672
673 for (i = 0; i < eh->e_phnum; i++) {
674 pp = &ph[i];
675 if (pp->p_type == PT_INTERP) {
676 if (pp->p_filesz < 2 || pp->p_filesz > MAXPATHLEN) {
677 DPRINTF("bad interpreter namelen %#jx",
678 (uintmax_t)pp->p_filesz);
679 error = ENOEXEC;
680 goto bad;
681 }
682 interp = PNBUF_GET();
683 if ((error = exec_read_from(l, epp->ep_vp,
684 pp->p_offset, interp, pp->p_filesz)) != 0)
685 goto bad;
686 /* Ensure interp is NUL-terminated and of the expected length */
687 if (strnlen(interp, pp->p_filesz) != pp->p_filesz - 1) {
688 DPRINTF("bad interpreter name");
689 error = ENOEXEC;
690 goto bad;
691 }
692 break;
693 }
694 }
695
696 /*
697 * On the same architecture, we may be emulating different systems.
698 * See which one will accept this executable.
699 *
700 * Probe functions would normally see if the interpreter (if any)
701 * exists. Emulation packages may possibly replace the interpreter in
702 * interp with a changed path (/emul/xxx/<path>).
703 */
704 pos = ELFDEFNNAME(NO_ADDR);
705 if (epp->ep_esch->u.elf_probe_func) {
706 vaddr_t startp = (vaddr_t)pos;
707
708 error = (*epp->ep_esch->u.elf_probe_func)(l, epp, eh, interp,
709 &startp);
710 if (error)
711 goto bad;
712 pos = (Elf_Addr)startp;
713 }
714
715 if (is_dyn)
716 elf_placedynexec(epp, eh, ph);
717
718 /*
719 * Load all the necessary sections
720 */
721 for (i = 0; i < eh->e_phnum; i++) {
722 Elf_Addr addr = ELFDEFNNAME(NO_ADDR);
723 u_long size = 0;
724
725 switch (ph[i].p_type) {
726 case PT_LOAD:
727 elf_load_psection(&epp->ep_vmcmds, epp->ep_vp,
728 &ph[i], &addr, &size, VMCMD_FIXED);
729
730 /*
731 * Consider this as text segment, if it is executable.
732 * If there is more than one text segment, pick the
733 * largest.
734 */
735 if (ph[i].p_flags & PF_X) {
736 if (epp->ep_taddr == ELFDEFNNAME(NO_ADDR) ||
737 size > epp->ep_tsize) {
738 epp->ep_taddr = addr;
739 epp->ep_tsize = size;
740 }
741 end_text = addr + size;
742 } else {
743 epp->ep_daddr = addr;
744 epp->ep_dsize = size;
745 }
746 if (ph[i].p_offset == 0) {
747 computed_phdr = ph[i].p_vaddr + eh->e_phoff;
748 }
749 break;
750
751 case PT_SHLIB:
752 /* SCO has these sections. */
753 case PT_INTERP:
754 /* Already did this one. */
755 case PT_DYNAMIC:
756 case PT_NOTE:
757 break;
758 case PT_PHDR:
759 /* Note address of program headers (in text segment) */
760 phdr = ph[i].p_vaddr;
761 break;
762
763 default:
764 /*
765 * Not fatal; we don't need to understand everything.
766 */
767 break;
768 }
769 }
770
771 if (epp->ep_vmcmds.evs_used == 0) {
772 /* No VMCMD; there was no PT_LOAD section, or those
773 * sections were empty */
774 DPRINTF("no vmcommands");
775 error = ENOEXEC;
776 goto bad;
777 }
778
779 if (epp->ep_daddr == ELFDEFNNAME(NO_ADDR)) {
780 epp->ep_daddr = round_page(end_text);
781 epp->ep_dsize = 0;
782 }
783
784 /*
785 * Check if we found a dynamically linked binary and arrange to load
786 * its interpreter
787 */
788 if (interp) {
789 u_int nused = epp->ep_vmcmds.evs_used;
790 u_long interp_offset = 0;
791
792 if ((error = elf_load_interp(l, epp, interp,
793 &epp->ep_vmcmds, &interp_offset, &pos)) != 0) {
794 goto bad;
795 }
796 if (epp->ep_vmcmds.evs_used == nused) {
797 /* elf_load_interp() has not set up any new VMCMD */
798 DPRINTF("no vmcommands for interpreter");
799 error = ENOEXEC;
800 goto bad;
801 }
802
803 ap = kmem_alloc(sizeof(*ap), KM_SLEEP);
804 ap->arg_interp = epp->ep_vmcmds.evs_cmds[nused].ev_addr;
805 epp->ep_entryoffset = interp_offset;
806 epp->ep_entry = ap->arg_interp + interp_offset;
807 PNBUF_PUT(interp);
808 interp = NULL;
809 } else {
810 epp->ep_entry = eh->e_entry;
811 if (epp->ep_flags & EXEC_FORCEAUX) {
812 ap = kmem_alloc(sizeof(*ap), KM_SLEEP);
813 ap->arg_interp = (vaddr_t)NULL;
814 } else
815 ap = NULL;
816 }
817
818 if (ap) {
819 ap->arg_phaddr = phdr ? phdr : computed_phdr;
820 ap->arg_phentsize = eh->e_phentsize;
821 ap->arg_phnum = eh->e_phnum;
822 ap->arg_entry = eh->e_entry;
823 epp->ep_emul_arg = ap;
824 epp->ep_emul_arg_free = elf_free_emul_arg;
825 }
826
827#ifdef ELF_MAP_PAGE_ZERO
828 /* Dell SVR4 maps page zero, yeuch! */
829 NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, PAGE_SIZE, 0,
830 epp->ep_vp, 0, VM_PROT_READ);
831#endif
832
833 error = (*epp->ep_esch->es_setup_stack)(l, epp);
834 if (error)
835 goto bad;
836
837 kmem_free(ph, phsize);
838 return 0;
839
840bad:
841 if (interp)
842 PNBUF_PUT(interp);
843 exec_free_emul_arg(epp);
844 kmem_free(ph, phsize);
845 kill_vmcmds(&epp->ep_vmcmds);
846 return error;
847}
848
849int
850netbsd_elf_signature(struct lwp *l, struct exec_package *epp,
851 Elf_Ehdr *eh)
852{
853 size_t i;
854 Elf_Shdr *sh;
855 Elf_Nhdr *np;
856 size_t shsize, nsize;
857 int error;
858 int isnetbsd = 0;
859 char *ndata, *ndesc;
860
861#ifdef DIAGNOSTIC
862 const char *badnote;
863#define BADNOTE(n) badnote = (n)
864#else
865#define BADNOTE(n)
866#endif
867
868 epp->ep_pax_flags = 0;
869 if (eh->e_shnum > ELF_MAXSHNUM || eh->e_shnum == 0) {
870 DPRINTF("no signature %#x", eh->e_shnum);
871 return ENOEXEC;
872 }
873
874 shsize = eh->e_shnum * sizeof(Elf_Shdr);
875 sh = kmem_alloc(shsize, KM_SLEEP);
876 error = exec_read_from(l, epp->ep_vp, eh->e_shoff, sh, shsize);
877 if (error)
878 goto out;
879
880 np = kmem_alloc(ELF_MAXNOTESIZE, KM_SLEEP);
881 for (i = 0; i < eh->e_shnum; i++) {
882 Elf_Shdr *shp = &sh[i];
883
884 if (shp->sh_type != SHT_NOTE ||
885 shp->sh_size > ELF_MAXNOTESIZE ||
886 shp->sh_size < sizeof(Elf_Nhdr) + ELF_NOTE_NETBSD_NAMESZ)
887 continue;
888
889 error = exec_read_from(l, epp->ep_vp, shp->sh_offset, np,
890 shp->sh_size);
891 if (error)
892 continue;
893
894 /* Point to the note, skip the header */
895 ndata = (char *)(np + 1);
896
897 /*
898 * Padding is present if necessary to ensure 4-byte alignment.
899 * The actual section size is therefore:
900 * header size + 4-byte aligned name + 4-byte aligned desc
901 * Ensure this size is consistent with what is indicated
902 * in sh_size. The first check avoids integer overflows.
903 *
904 * Binaries from before NetBSD 1.6 have two notes in the same
905 * note section. The second note was never used, so as long as
906 * the section is at least as big as it should be, it's ok.
907 * These binaries also have a second note section with a note of
908 * type ELF_NOTE_TYPE_NETBSD_TAG, which can be ignored as well.
909 */
910 if (np->n_namesz > shp->sh_size || np->n_descsz > shp->sh_size) {
911 BADNOTE("note size limit");
912 goto bad;
913 }
914 nsize = sizeof(*np) + roundup(np->n_namesz, 4) +
915 roundup(np->n_descsz, 4);
916 if (nsize > shp->sh_size) {
917 BADNOTE("note size");
918 goto bad;
919 }
920 ndesc = ndata + roundup(np->n_namesz, 4);
921
922 switch (np->n_type) {
923 case ELF_NOTE_TYPE_NETBSD_TAG:
924 /* It is us */
925 if (np->n_namesz == ELF_NOTE_NETBSD_NAMESZ &&
926 np->n_descsz == ELF_NOTE_NETBSD_DESCSZ &&
927 memcmp(ndata, ELF_NOTE_NETBSD_NAME,
928 ELF_NOTE_NETBSD_NAMESZ) == 0) {
929 memcpy(&epp->ep_osversion, ndesc,
930 ELF_NOTE_NETBSD_DESCSZ);
931 isnetbsd = 1;
932 break;
933 }
934
935 /*
936 * Ignore SuSE tags; SuSE's n_type is the same the
937 * NetBSD one.
938 */
939 if (np->n_namesz == ELF_NOTE_SUSE_NAMESZ &&
940 memcmp(ndata, ELF_NOTE_SUSE_NAME,
941 ELF_NOTE_SUSE_NAMESZ) == 0)
942 break;
943 /*
944 * Ignore old GCC
945 */
946 if (np->n_namesz == ELF_NOTE_OGCC_NAMESZ &&
947 memcmp(ndata, ELF_NOTE_OGCC_NAME,
948 ELF_NOTE_OGCC_NAMESZ) == 0)
949 break;
950 BADNOTE("NetBSD tag");
951 goto bad;
952
953 case ELF_NOTE_TYPE_PAX_TAG:
954 if (np->n_namesz == ELF_NOTE_PAX_NAMESZ &&
955 np->n_descsz == ELF_NOTE_PAX_DESCSZ &&
956 memcmp(ndata, ELF_NOTE_PAX_NAME,
957 ELF_NOTE_PAX_NAMESZ) == 0) {
958 uint32_t flags;
959 memcpy(&flags, ndesc, sizeof(flags));
960 /* Convert the flags and insert them into
961 * the exec package. */
962 pax_setup_elf_flags(epp, flags);
963 break;
964 }
965 BADNOTE("PaX tag");
966 goto bad;
967
968 case ELF_NOTE_TYPE_MARCH_TAG:
969 /* Copy the machine arch into the package. */
970 if (np->n_namesz == ELF_NOTE_MARCH_NAMESZ
971 && memcmp(ndata, ELF_NOTE_MARCH_NAME,
972 ELF_NOTE_MARCH_NAMESZ) == 0) {
973 /* Do not truncate the buffer */
974 if (np->n_descsz > sizeof(epp->ep_machine_arch)) {
975 BADNOTE("description size limit");
976 goto bad;
977 }
978 /*
979 * Ensure ndesc is NUL-terminated and of the
980 * expected length.
981 */
982 if (strnlen(ndesc, np->n_descsz) + 1 !=
983 np->n_descsz) {
984 BADNOTE("description size");
985 goto bad;
986 }
987 strlcpy(epp->ep_machine_arch, ndesc,
988 sizeof(epp->ep_machine_arch));
989 break;
990 }
991 BADNOTE("march tag");
992 goto bad;
993
994 case ELF_NOTE_TYPE_MCMODEL_TAG:
995 /* arch specific check for code model */
996#ifdef ELF_MD_MCMODEL_CHECK
997 if (np->n_namesz == ELF_NOTE_MCMODEL_NAMESZ
998 && memcmp(ndata, ELF_NOTE_MCMODEL_NAME,
999 ELF_NOTE_MCMODEL_NAMESZ) == 0) {
1000 ELF_MD_MCMODEL_CHECK(epp, ndesc, np->n_descsz);
1001 break;
1002 }
1003 BADNOTE("mcmodel tag");
1004 goto bad;
1005#endif
1006 break;
1007
1008 case ELF_NOTE_TYPE_SUSE_VERSION_TAG:
1009 break;
1010
1011 case ELF_NOTE_TYPE_GO_BUILDID_TAG:
1012 break;
1013
1014 default:
1015 BADNOTE("unknown tag");
1016bad:
1017#ifdef DIAGNOSTIC
1018 /* Ignore GNU tags */
1019 if (np->n_namesz == ELF_NOTE_GNU_NAMESZ &&
1020 memcmp(ndata, ELF_NOTE_GNU_NAME,
1021 ELF_NOTE_GNU_NAMESZ) == 0)
1022 break;
1023
1024 int ns = MIN(np->n_namesz, shp->sh_size - sizeof(*np));
1025 printf("%s: Unknown elf note type %d (%s): "
1026 "[namesz=%d, descsz=%d name=%-*.*s]\n",
1027 epp->ep_kname, np->n_type, badnote, np->n_namesz,
1028 np->n_descsz, ns, ns, ndata);
1029#endif
1030 break;
1031 }
1032 }
1033 kmem_free(np, ELF_MAXNOTESIZE);
1034
1035 error = isnetbsd ? 0 : ENOEXEC;
1036#ifdef DEBUG_ELF
1037 if (error)
1038 DPRINTF("not netbsd");
1039#endif
1040out:
1041 kmem_free(sh, shsize);
1042 return error;
1043}
1044
1045int
1046netbsd_elf_probe(struct lwp *l, struct exec_package *epp, void *eh, char *itp,
1047 vaddr_t *pos)
1048{
1049 int error;
1050
1051 if ((error = netbsd_elf_signature(l, epp, eh)) != 0)
1052 return error;
1053#ifdef ELF_MD_PROBE_FUNC
1054 if ((error = ELF_MD_PROBE_FUNC(l, epp, eh, itp, pos)) != 0)
1055 return error;
1056#elif defined(ELF_INTERP_NON_RELOCATABLE)
1057 *pos = ELF_LINK_ADDR;
1058#endif
1059 epp->ep_flags |= EXEC_FORCEAUX;
1060 return 0;
1061}
1062
1063void
1064elf_free_emul_arg(void *arg)
1065{
1066 struct elf_args *ap = arg;
1067 KASSERT(ap != NULL);
1068 kmem_free(ap, sizeof(*ap));
1069}
1070