1 /* $NetBSD: exec_elf.c,v 1.107 2024/12/06 16:19:41 riastradh Exp $ */
2
3 /*-
4 * Copyright (c) 1994, 2000, 2005, 2015, 2020 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 1.107 2024/12/06 16:19:41 riastradh Exp $");
61
62 #ifdef _KERNEL_OPT
63 #include "opt_pax.h"
64 #endif /* _KERNEL_OPT */
65
66 #include <sys/param.h>
67 #include <sys/types.h>
68
69 #include <sys/bitops.h>
70 #include <sys/cpu.h>
71 #include <sys/exec.h>
72 #include <sys/exec_elf.h>
73 #include <sys/kauth.h>
74 #include <sys/kmem.h>
75 #include <sys/mount.h>
76 #include <sys/namei.h>
77 #include <sys/pax.h>
78 #include <sys/proc.h>
79 #include <sys/sdt.h>
80 #include <sys/signalvar.h>
81 #include <sys/stat.h>
82 #include <sys/syscall.h>
83 #include <sys/vnode.h>
84
85 #include <machine/reg.h>
86
87 #include <compat/common/compat_util.h>
88
89 #include <uvm/uvm_param.h>
90
91 #define elf_check_header ELFNAME(check_header)
92 #define elf_copyargs ELFNAME(copyargs)
93 #define elf_populate_auxv ELFNAME(populate_auxv)
94 #define elf_load_interp ELFNAME(load_interp)
95 #define elf_load_psection ELFNAME(load_psection)
96 #define exec_elf_makecmds ELFNAME2(exec,makecmds)
97 #define netbsd_elf_signature ELFNAME2(netbsd,signature)
98 #define netbsd_elf_note ELFNAME2(netbsd,note)
99 #define netbsd_elf_probe ELFNAME2(netbsd,probe)
100 #define coredump ELFNAMEEND(coredump)
101 #define elf_free_emul_arg ELFNAME(free_emul_arg)
102
103 static int
104 elf_load_interp(struct lwp *, struct exec_package *, char *,
105 struct exec_vmcmd_set *, u_long *, Elf_Addr *);
106 static int
107 elf_load_psection(struct exec_vmcmd_set *, struct vnode *, const Elf_Phdr *,
108 Elf_Addr *, u_long *, int);
109
110 int netbsd_elf_signature(struct lwp *, struct exec_package *, Elf_Ehdr *);
111 int netbsd_elf_note(struct exec_package *, const Elf_Nhdr *, const char *,
112 const char *);
113 int netbsd_elf_probe(struct lwp *, struct exec_package *, void *, char *,
114 vaddr_t *);
115
116 static void elf_free_emul_arg(void *);
117
118 #ifdef DEBUG_ELF
119 #define DPRINTF(a, ...) printf("%s: " a "\n", __func__, ##__VA_ARGS__)
120 #else
121 #define DPRINTF(a, ...)
122 #endif
123
124 /* round up and down to page boundaries. */
125 #define ELF_ROUND(a, b) (((a) + (b) - 1) & ~((b) - 1))
126 #define ELF_TRUNC(a, b) ((a) & ~((b) - 1))
127
128 static int
elf_placedynexec(struct exec_package * epp,Elf_Ehdr * eh,Elf_Phdr * ph)129 elf_placedynexec(struct exec_package *epp, Elf_Ehdr *eh, Elf_Phdr *ph)
130 {
131 Elf_Addr align, offset;
132 int i;
133
134 for (align = 1, i = 0; i < eh->e_phnum; i++)
135 if (ph[i].p_type == PT_LOAD && ph[i].p_align > align)
136 align = ph[i].p_align;
137
138 offset = (Elf_Addr)pax_aslr_exec_offset(epp, align);
139 if (offset < epp->ep_vm_minaddr)
140 offset = roundup(epp->ep_vm_minaddr, align);
141 if ((offset & (align - 1)) != 0) {
142 DPRINTF("bad offset=%#jx align=%#jx",
143 (uintmax_t)offset, (uintmax_t)align);
144 return SET_ERROR(EINVAL);
145 }
146
147 for (i = 0; i < eh->e_phnum; i++)
148 ph[i].p_vaddr += offset;
149 epp->ep_entryoffset = offset;
150 eh->e_entry += offset;
151 return 0;
152 }
153
154
155 int
elf_populate_auxv(struct lwp * l,struct exec_package * pack,char ** stackp)156 elf_populate_auxv(struct lwp *l, struct exec_package *pack, char **stackp)
157 {
158 size_t len, vlen;
159 AuxInfo ai[ELF_AUX_ENTRIES], *a, *execname;
160 struct elf_args *ap;
161 char *path = l->l_proc->p_path;
162 int error;
163
164 execname = NULL;
165 a = ai;
166
167 memset(ai, 0, sizeof(ai));
168
169 /*
170 * Push extra arguments on the stack needed by dynamically
171 * linked binaries
172 */
173 if ((ap = (struct elf_args *)pack->ep_emul_arg)) {
174 struct vattr *vap = pack->ep_vap;
175
176 a->a_type = AT_PHDR;
177 a->a_v = ap->arg_phaddr;
178 a++;
179
180 a->a_type = AT_PHENT;
181 a->a_v = ap->arg_phentsize;
182 a++;
183
184 a->a_type = AT_PHNUM;
185 a->a_v = ap->arg_phnum;
186 a++;
187
188 a->a_type = AT_PAGESZ;
189 a->a_v = PAGE_SIZE;
190 a++;
191
192 a->a_type = AT_BASE;
193 a->a_v = ap->arg_interp;
194 a++;
195
196 a->a_type = AT_FLAGS;
197 a->a_v = 0;
198 a++;
199
200 a->a_type = AT_ENTRY;
201 a->a_v = ap->arg_entry;
202 a++;
203
204 a->a_type = AT_STACKBASE;
205 a->a_v = l->l_proc->p_stackbase;
206 a++;
207
208 a->a_type = AT_EUID;
209 if (vap->va_mode & S_ISUID)
210 a->a_v = vap->va_uid;
211 else
212 a->a_v = kauth_cred_geteuid(l->l_cred);
213 a++;
214
215 a->a_type = AT_RUID;
216 a->a_v = kauth_cred_getuid(l->l_cred);
217 a++;
218
219 a->a_type = AT_EGID;
220 if (vap->va_mode & S_ISGID)
221 a->a_v = vap->va_gid;
222 else
223 a->a_v = kauth_cred_getegid(l->l_cred);
224 a++;
225
226 a->a_type = AT_RGID;
227 a->a_v = kauth_cred_getgid(l->l_cred);
228 a++;
229
230 /* "/" means fexecve(2) could not resolve the pathname */
231 if (path[0] == '/' && path[1] != '\0') {
232 execname = a;
233 a->a_type = AT_SUN_EXECNAME;
234 a++;
235 }
236
237 exec_free_emul_arg(pack);
238 }
239
240 a->a_type = AT_NULL;
241 a->a_v = 0;
242 a++;
243
244 vlen = (a - ai) * sizeof(ai[0]);
245
246 KASSERT(vlen <= sizeof(ai));
247
248 if (execname) {
249 execname->a_v = (uintptr_t)(*stackp + vlen);
250 len = strlen(path) + 1;
251 if ((error = copyout(path, (*stackp + vlen), len)) != 0)
252 return error;
253 len = ALIGN(len);
254 } else {
255 len = 0;
256 }
257
258 if ((error = copyout(ai, *stackp, vlen)) != 0)
259 return error;
260 *stackp += vlen + len;
261
262 return 0;
263 }
264
265 /*
266 * Copy arguments onto the stack in the normal way, but add some
267 * extra information in case of dynamic binding.
268 */
269 int
elf_copyargs(struct lwp * l,struct exec_package * pack,struct ps_strings * arginfo,char ** stackp,void * argp)270 elf_copyargs(struct lwp *l, struct exec_package *pack,
271 struct ps_strings *arginfo, char **stackp, void *argp)
272 {
273 int error;
274
275 if ((error = copyargs(l, pack, arginfo, stackp, argp)) != 0)
276 return error;
277
278 return elf_populate_auxv(l, pack, stackp);
279 }
280
281 /*
282 * elf_check_header():
283 *
284 * Check header for validity; return 0 if ok, ENOEXEC if error
285 */
286 int
elf_check_header(Elf_Ehdr * eh)287 elf_check_header(Elf_Ehdr *eh)
288 {
289
290 if (memcmp(eh->e_ident, ELFMAG, SELFMAG) != 0 ||
291 eh->e_ident[EI_CLASS] != ELFCLASS) {
292 DPRINTF("bad magic e_ident[EI_MAG0,EI_MAG3] %#x%x%x%x, "
293 "e_ident[EI_CLASS] %#x", eh->e_ident[EI_MAG0],
294 eh->e_ident[EI_MAG1], eh->e_ident[EI_MAG2],
295 eh->e_ident[EI_MAG3], eh->e_ident[EI_CLASS]);
296 return SET_ERROR(ENOEXEC);
297 }
298
299 switch (eh->e_machine) {
300
301 ELFDEFNNAME(MACHDEP_ID_CASES)
302
303 default:
304 DPRINTF("bad machine %#x", eh->e_machine);
305 return SET_ERROR(ENOEXEC);
306 }
307
308 if (ELF_EHDR_FLAGS_OK(eh) == 0) {
309 DPRINTF("bad flags %#x", eh->e_flags);
310 return SET_ERROR(ENOEXEC);
311 }
312
313 if (eh->e_shnum > ELF_MAXSHNUM || eh->e_phnum > ELF_MAXPHNUM) {
314 DPRINTF("bad shnum/phnum %#x/%#x", eh->e_shnum, eh->e_phnum);
315 return SET_ERROR(ENOEXEC);
316 }
317
318 return 0;
319 }
320
321 /*
322 * elf_load_psection():
323 *
324 * Load a psection at the appropriate address
325 */
326 static int
elf_load_psection(struct exec_vmcmd_set * vcset,struct vnode * vp,const Elf_Phdr * ph,Elf_Addr * addr,u_long * size,int flags)327 elf_load_psection(struct exec_vmcmd_set *vcset, struct vnode *vp,
328 const Elf_Phdr *ph, Elf_Addr *addr, u_long *size, int flags)
329 {
330 u_long msize, psize, rm, rf;
331 long diff, offset;
332 int vmprot = 0;
333
334 KASSERT(VOP_ISLOCKED(vp) != LK_NONE);
335
336 /*
337 * If the user specified an address, then we load there.
338 */
339 if (*addr == ELFDEFNNAME(NO_ADDR))
340 *addr = ph->p_vaddr;
341
342 if (ph->p_align > 1) {
343 /*
344 * Make sure we are virtually aligned as we are supposed to be.
345 */
346 diff = ph->p_vaddr - ELF_TRUNC(ph->p_vaddr, ph->p_align);
347 if (*addr - diff != ELF_TRUNC(*addr, ph->p_align)) {
348 DPRINTF("bad alignment %#jx != %#jx\n",
349 (uintptr_t)(*addr - diff),
350 (uintptr_t)ELF_TRUNC(*addr, ph->p_align));
351 return SET_ERROR(EINVAL);
352 }
353 /*
354 * But make sure to not map any pages before the start of the
355 * psection by limiting the difference to within a page.
356 */
357 diff &= PAGE_MASK;
358 } else
359 diff = 0;
360
361 vmprot |= (ph->p_flags & PF_R) ? VM_PROT_READ : 0;
362 vmprot |= (ph->p_flags & PF_W) ? VM_PROT_WRITE : 0;
363 vmprot |= (ph->p_flags & PF_X) ? VM_PROT_EXECUTE : 0;
364
365 /*
366 * Adjust everything so it all starts on a page boundary.
367 */
368 *addr -= diff;
369 offset = ph->p_offset - diff;
370 *size = ph->p_filesz + diff;
371 msize = ph->p_memsz + diff;
372
373 if (ph->p_align >= PAGE_SIZE) {
374 if ((ph->p_flags & PF_W) != 0) {
375 /*
376 * Because the pagedvn pager can't handle zero fill
377 * of the last data page if it's not page aligned we
378 * map the last page readvn.
379 */
380 psize = trunc_page(*size);
381 } else {
382 psize = round_page(*size);
383 }
384 } else {
385 psize = *size;
386 }
387
388 if (psize > 0) {
389 NEW_VMCMD2(vcset, ph->p_align < PAGE_SIZE ?
390 vmcmd_map_readvn : vmcmd_map_pagedvn, psize, *addr, vp,
391 offset, vmprot, flags);
392 flags &= VMCMD_RELATIVE;
393 }
394 if (psize < *size) {
395 NEW_VMCMD2(vcset, vmcmd_map_readvn, *size - psize,
396 *addr + psize, vp, offset + psize, vmprot, flags);
397 }
398
399 /*
400 * Check if we need to extend the size of the segment (does
401 * bss extend page the next page boundary)?
402 */
403 rm = round_page(*addr + msize);
404 rf = round_page(*addr + *size);
405
406 if (rm != rf) {
407 NEW_VMCMD2(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP,
408 0, vmprot, flags & VMCMD_RELATIVE);
409 *size = msize;
410 }
411 return 0;
412 }
413
414 /*
415 * elf_load_interp():
416 *
417 * Load an interpreter pointed to by path.
418 */
419 static int
elf_load_interp(struct lwp * l,struct exec_package * epp,char * path,struct exec_vmcmd_set * vcset,u_long * entryoff,Elf_Addr * last)420 elf_load_interp(struct lwp *l, struct exec_package *epp, char *path,
421 struct exec_vmcmd_set *vcset, u_long *entryoff, Elf_Addr *last)
422 {
423 int error, i;
424 struct vnode *vp;
425 Elf_Ehdr eh;
426 Elf_Phdr *ph = NULL;
427 const Elf_Phdr *base_ph;
428 const Elf_Phdr *last_ph;
429 u_long phsize;
430 Elf_Addr addr = *last;
431 struct proc *p;
432 bool use_topdown;
433
434 p = l->l_proc;
435
436 KASSERT(p->p_vmspace);
437 KASSERT(p->p_vmspace != proc0.p_vmspace);
438
439 #ifdef __USE_TOPDOWN_VM
440 use_topdown = epp->ep_flags & EXEC_TOPDOWN_VM;
441 #else
442 use_topdown = false;
443 #endif
444
445 /*
446 * 1. open file
447 * 2. read filehdr
448 * 3. map text, data, and bss out of it using VM_*
449 */
450 vp = epp->ep_interp;
451 if (vp == NULL) {
452 error = emul_find_interp(l, epp, path);
453 if (error != 0)
454 return error;
455 vp = epp->ep_interp;
456 }
457 /* We'll tidy this ourselves - otherwise we have locking issues */
458 epp->ep_interp = NULL;
459 vn_lock(vp, LK_SHARED | LK_RETRY);
460
461 /*
462 * Similarly, if it's not marked as executable, or it's not a regular
463 * file, we don't allow it to be used.
464 */
465 if (vp->v_type != VREG) {
466 error = SET_ERROR(EACCES);
467 goto bad;
468 }
469 if ((error = VOP_ACCESS(vp, VEXEC, l->l_cred)) != 0)
470 goto bad;
471
472 /*
473 * Check mount point. Though we're not trying to exec this binary,
474 * we will be executing code from it, so if the mount point
475 * disallows execution or set-id-ness, we punt or kill the set-id.
476 */
477 if (vp->v_mount->mnt_flag & MNT_NOEXEC) {
478 error = SET_ERROR(EACCES);
479 goto bad;
480 }
481 if (vp->v_mount->mnt_flag & MNT_NOSUID)
482 epp->ep_vap->va_mode &= ~(S_ISUID | S_ISGID);
483
484 error = vn_marktext(vp);
485 if (error)
486 goto bad;
487
488 error = exec_read(l, vp, 0, &eh, sizeof(eh), IO_NODELOCKED);
489 if (error != 0)
490 goto bad;
491
492 if ((error = elf_check_header(&eh)) != 0)
493 goto bad;
494 if (eh.e_type != ET_DYN || eh.e_phnum == 0) {
495 DPRINTF("bad interpreter type %#x", eh.e_type);
496 error = SET_ERROR(ENOEXEC);
497 goto bad;
498 }
499
500 phsize = eh.e_phnum * sizeof(Elf_Phdr);
501 ph = kmem_alloc(phsize, KM_SLEEP);
502
503 error = exec_read(l, vp, eh.e_phoff, ph, phsize, IO_NODELOCKED);
504 if (error != 0)
505 goto bad;
506
507 #ifdef ELF_INTERP_NON_RELOCATABLE
508 /*
509 * Evil hack: Only MIPS should be non-relocatable, and the
510 * psections should have a high address (typically 0x5ffe0000).
511 * If it's now relocatable, it should be linked at 0 and the
512 * psections should have zeros in the upper part of the address.
513 * Otherwise, force the load at the linked address.
514 */
515 if (*last == ELF_LINK_ADDR && (ph->p_vaddr & 0xffff0000) == 0)
516 *last = ELFDEFNNAME(NO_ADDR);
517 #endif
518
519 /*
520 * If no position to load the interpreter was set by a probe
521 * function, pick the same address that a non-fixed mmap(0, ..)
522 * would (i.e. something safely out of the way).
523 */
524 if (*last == ELFDEFNNAME(NO_ADDR)) {
525 u_long limit = 0;
526 /*
527 * Find the start and ending addresses of the psections to
528 * be loaded. This will give us the size.
529 */
530 for (i = 0, base_ph = NULL; i < eh.e_phnum; i++) {
531 if (ph[i].p_type == PT_LOAD) {
532 u_long psize = ph[i].p_vaddr + ph[i].p_memsz;
533 if (base_ph == NULL)
534 base_ph = &ph[i];
535 if (psize > limit)
536 limit = psize;
537 }
538 }
539
540 if (base_ph == NULL) {
541 DPRINTF("no interpreter loadable sections");
542 error = SET_ERROR(ENOEXEC);
543 goto bad;
544 }
545
546 /*
547 * Now compute the size and load address.
548 */
549 addr = (*epp->ep_esch->es_emul->e_vm_default_addr)(p,
550 epp->ep_daddr,
551 round_page(limit) - trunc_page(base_ph->p_vaddr),
552 use_topdown);
553 addr += (Elf_Addr)pax_aslr_rtld_offset(epp, base_ph->p_align,
554 use_topdown);
555 } else {
556 addr = *last; /* may be ELF_LINK_ADDR */
557 }
558
559 /*
560 * Load all the necessary sections
561 */
562 for (i = 0, base_ph = NULL, last_ph = NULL; i < eh.e_phnum; i++) {
563 switch (ph[i].p_type) {
564 case PT_LOAD: {
565 u_long size;
566 int flags;
567
568 if (base_ph == NULL) {
569 /*
570 * First encountered psection is always the
571 * base psection. Make sure it's aligned
572 * properly (align down for topdown and align
573 * upwards for not topdown).
574 */
575 base_ph = &ph[i];
576 flags = VMCMD_BASE;
577 if (addr == ELF_LINK_ADDR)
578 addr = ph[i].p_vaddr;
579 if (use_topdown)
580 addr = ELF_TRUNC(addr, ph[i].p_align);
581 else
582 addr = ELF_ROUND(addr, ph[i].p_align);
583 } else {
584 u_long limit = round_page(last_ph->p_vaddr
585 + last_ph->p_memsz);
586 u_long base = trunc_page(ph[i].p_vaddr);
587
588 /*
589 * If there is a gap in between the psections,
590 * map it as inaccessible so nothing else
591 * mmap'ed will be placed there.
592 */
593 if (limit != base) {
594 NEW_VMCMD2(vcset, vmcmd_map_zero,
595 base - limit,
596 limit - base_ph->p_vaddr, NULLVP,
597 0, VM_PROT_NONE, VMCMD_RELATIVE);
598 }
599
600 addr = ph[i].p_vaddr - base_ph->p_vaddr;
601 flags = VMCMD_RELATIVE;
602 }
603 last_ph = &ph[i];
604 if ((error = elf_load_psection(vcset, vp, &ph[i], &addr,
605 &size, flags)) != 0)
606 goto bad;
607 /*
608 * If entry is within this psection then this
609 * must contain the .text section. *entryoff is
610 * relative to the base psection.
611 */
612 if (eh.e_entry >= ph[i].p_vaddr &&
613 eh.e_entry < (ph[i].p_vaddr + size)) {
614 *entryoff = eh.e_entry - base_ph->p_vaddr;
615 }
616 addr += size;
617 break;
618 }
619
620 default:
621 break;
622 }
623 }
624
625 kmem_free(ph, phsize);
626 /*
627 * This value is ignored if TOPDOWN.
628 */
629 *last = addr;
630 vput(vp);
631 return 0;
632
633 bad:
634 if (ph != NULL)
635 kmem_free(ph, phsize);
636 vput(vp);
637 return error;
638 }
639
640 /*
641 * exec_elf_makecmds(): Prepare an Elf binary's exec package
642 *
643 * First, set of the various offsets/lengths in the exec package.
644 *
645 * Then, mark the text image busy (so it can be demand paged) or error
646 * out if this is not possible. Finally, set up vmcmds for the
647 * text, data, bss, and stack segments.
648 */
649 int
exec_elf_makecmds(struct lwp * l,struct exec_package * epp)650 exec_elf_makecmds(struct lwp *l, struct exec_package *epp)
651 {
652 Elf_Ehdr *eh = epp->ep_hdr;
653 Elf_Phdr *ph, *pp;
654 Elf_Addr phdr = 0, computed_phdr = 0, pos = 0, end_text = 0;
655 int error, i;
656 char *interp = NULL;
657 u_long phsize;
658 struct elf_args *ap;
659 bool is_dyn = false;
660
661 if (epp->ep_hdrvalid < sizeof(Elf_Ehdr)) {
662 DPRINTF("small header %#x", epp->ep_hdrvalid);
663 return SET_ERROR(ENOEXEC);
664 }
665 if ((error = elf_check_header(eh)) != 0)
666 return error;
667
668 if (eh->e_type == ET_DYN)
669 /* PIE, and some libs have an entry point */
670 is_dyn = true;
671 else if (eh->e_type != ET_EXEC) {
672 DPRINTF("bad type %#x", eh->e_type);
673 return SET_ERROR(ENOEXEC);
674 }
675
676 if (eh->e_phnum == 0) {
677 DPRINTF("no program headers");
678 return SET_ERROR(ENOEXEC);
679 }
680
681 /* XXX only LK_EXCLUSIVE to match all others - allow spinning */
682 vn_lock(epp->ep_vp, LK_EXCLUSIVE | LK_RETRY);
683 error = vn_marktext(epp->ep_vp);
684 if (error) {
685 VOP_UNLOCK(epp->ep_vp);
686 return error;
687 }
688
689 /*
690 * Allocate space to hold all the program headers, and read them
691 * from the file
692 */
693 phsize = eh->e_phnum * sizeof(Elf_Phdr);
694 ph = kmem_alloc(phsize, KM_SLEEP);
695
696 error = exec_read(l, epp->ep_vp, eh->e_phoff, ph, phsize,
697 IO_NODELOCKED);
698 if (error != 0) {
699 VOP_UNLOCK(epp->ep_vp);
700 goto bad;
701 }
702
703 epp->ep_taddr = epp->ep_tsize = ELFDEFNNAME(NO_ADDR);
704 epp->ep_daddr = epp->ep_dsize = ELFDEFNNAME(NO_ADDR);
705
706 for (i = 0; i < eh->e_phnum; i++) {
707 pp = &ph[i];
708 if (pp->p_type == PT_INTERP) {
709 if (pp->p_filesz < 2 || pp->p_filesz > MAXPATHLEN) {
710 DPRINTF("bad interpreter namelen %#jx",
711 (uintmax_t)pp->p_filesz);
712 error = SET_ERROR(ENOEXEC);
713 VOP_UNLOCK(epp->ep_vp);
714 goto bad;
715 }
716 interp = PNBUF_GET();
717 error = exec_read(l, epp->ep_vp, pp->p_offset, interp,
718 pp->p_filesz, IO_NODELOCKED);
719 if (error != 0) {
720 VOP_UNLOCK(epp->ep_vp);
721 goto bad;
722 }
723 /* Ensure interp is NUL-terminated and of the expected length */
724 if (strnlen(interp, pp->p_filesz) != pp->p_filesz - 1) {
725 DPRINTF("bad interpreter name");
726 error = SET_ERROR(ENOEXEC);
727 VOP_UNLOCK(epp->ep_vp);
728 goto bad;
729 }
730 break;
731 }
732 }
733
734 /*
735 * On the same architecture, we may be emulating different systems.
736 * See which one will accept this executable.
737 *
738 * Probe functions would normally see if the interpreter (if any)
739 * exists. Emulation packages may possibly replace the interpreter in
740 * interp with a changed path (/emul/xxx/<path>).
741 */
742 pos = ELFDEFNNAME(NO_ADDR);
743 if (epp->ep_esch->u.elf_probe_func) {
744 vaddr_t startp = (vaddr_t)pos;
745
746 error = (*epp->ep_esch->u.elf_probe_func)(l, epp, eh, interp,
747 &startp);
748 if (error) {
749 VOP_UNLOCK(epp->ep_vp);
750 goto bad;
751 }
752 pos = (Elf_Addr)startp;
753 }
754
755 if (is_dyn && (error = elf_placedynexec(epp, eh, ph)) != 0) {
756 VOP_UNLOCK(epp->ep_vp);
757 goto bad;
758 }
759
760 /*
761 * Load all the necessary sections
762 */
763 for (i = 0; i < eh->e_phnum; i++) {
764 Elf_Addr addr = ELFDEFNNAME(NO_ADDR);
765 u_long size = 0;
766
767 switch (ph[i].p_type) {
768 case PT_LOAD:
769 if ((error = elf_load_psection(&epp->ep_vmcmds,
770 epp->ep_vp, &ph[i], &addr, &size, VMCMD_FIXED))
771 != 0) {
772 VOP_UNLOCK(epp->ep_vp);
773 goto bad;
774 }
775
776 /*
777 * Consider this as text segment, if it is executable.
778 * If there is more than one text segment, pick the
779 * largest.
780 */
781 if (ph[i].p_flags & PF_X) {
782 if (epp->ep_taddr == ELFDEFNNAME(NO_ADDR) ||
783 size > epp->ep_tsize) {
784 epp->ep_taddr = addr;
785 epp->ep_tsize = size;
786 }
787 end_text = addr + size;
788 } else {
789 epp->ep_daddr = addr;
790 epp->ep_dsize = size;
791 }
792 if (ph[i].p_offset == 0) {
793 computed_phdr = ph[i].p_vaddr + eh->e_phoff;
794 }
795 break;
796
797 case PT_SHLIB:
798 /* SCO has these sections. */
799 case PT_INTERP:
800 /* Already did this one. */
801 case PT_DYNAMIC:
802 case PT_NOTE:
803 break;
804 case PT_PHDR:
805 /* Note address of program headers (in text segment) */
806 phdr = ph[i].p_vaddr;
807 break;
808
809 default:
810 /*
811 * Not fatal; we don't need to understand everything.
812 */
813 break;
814 }
815 }
816
817 /* Now done with the vnode. */
818 VOP_UNLOCK(epp->ep_vp);
819
820 if (epp->ep_vmcmds.evs_used == 0) {
821 /* No VMCMD; there was no PT_LOAD section, or those
822 * sections were empty */
823 DPRINTF("no vmcommands");
824 error = SET_ERROR(ENOEXEC);
825 goto bad;
826 }
827
828 if (epp->ep_daddr == ELFDEFNNAME(NO_ADDR)) {
829 epp->ep_daddr = round_page(end_text);
830 epp->ep_dsize = 0;
831 }
832
833 /*
834 * Check if we found a dynamically linked binary and arrange to load
835 * its interpreter
836 */
837 if (interp) {
838 u_int nused = epp->ep_vmcmds.evs_used;
839 u_long interp_offset = 0;
840
841 if ((error = elf_load_interp(l, epp, interp,
842 &epp->ep_vmcmds, &interp_offset, &pos)) != 0) {
843 goto bad;
844 }
845 if (epp->ep_vmcmds.evs_used == nused) {
846 /* elf_load_interp() has not set up any new VMCMD */
847 DPRINTF("no vmcommands for interpreter");
848 error = SET_ERROR(ENOEXEC);
849 goto bad;
850 }
851
852 ap = kmem_alloc(sizeof(*ap), KM_SLEEP);
853 ap->arg_interp = epp->ep_vmcmds.evs_cmds[nused].ev_addr;
854 epp->ep_entryoffset = interp_offset;
855 epp->ep_entry = ap->arg_interp + interp_offset;
856 PNBUF_PUT(interp);
857 interp = NULL;
858 } else {
859 epp->ep_entry = eh->e_entry;
860 if (epp->ep_flags & EXEC_FORCEAUX) {
861 ap = kmem_zalloc(sizeof(*ap), KM_SLEEP);
862 ap->arg_interp = (vaddr_t)NULL;
863 } else {
864 ap = NULL;
865 }
866 }
867
868 if (ap) {
869 ap->arg_phaddr = phdr ? phdr : computed_phdr;
870 ap->arg_phentsize = eh->e_phentsize;
871 ap->arg_phnum = eh->e_phnum;
872 ap->arg_entry = eh->e_entry;
873 epp->ep_emul_arg = ap;
874 epp->ep_emul_arg_free = elf_free_emul_arg;
875 }
876
877 #ifdef ELF_MAP_PAGE_ZERO
878 /* Dell SVR4 maps page zero, yeuch! */
879 NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, PAGE_SIZE, 0,
880 epp->ep_vp, 0, VM_PROT_READ);
881 #endif
882
883 error = (*epp->ep_esch->es_setup_stack)(l, epp);
884 if (error)
885 goto bad;
886
887 kmem_free(ph, phsize);
888 return 0;
889
890 bad:
891 if (interp)
892 PNBUF_PUT(interp);
893 exec_free_emul_arg(epp);
894 kmem_free(ph, phsize);
895 kill_vmcmds(&epp->ep_vmcmds);
896 return error;
897 }
898
899 int
netbsd_elf_signature(struct lwp * l,struct exec_package * epp,Elf_Ehdr * eh)900 netbsd_elf_signature(struct lwp *l, struct exec_package *epp,
901 Elf_Ehdr *eh)
902 {
903 size_t i;
904 Elf_Phdr *ph;
905 size_t phsize;
906 char *nbuf;
907 int error;
908 int isnetbsd = 0;
909
910 epp->ep_pax_flags = 0;
911
912 if (eh->e_phnum > ELF_MAXPHNUM || eh->e_phnum == 0) {
913 DPRINTF("no signature %#x", eh->e_phnum);
914 return SET_ERROR(ENOEXEC);
915 }
916
917 phsize = eh->e_phnum * sizeof(Elf_Phdr);
918 ph = kmem_alloc(phsize, KM_SLEEP);
919 error = exec_read(l, epp->ep_vp, eh->e_phoff, ph, phsize,
920 IO_NODELOCKED);
921 if (error)
922 goto out;
923
924 nbuf = kmem_alloc(ELF_MAXNOTESIZE, KM_SLEEP);
925 for (i = 0; i < eh->e_phnum; i++) {
926 const char *nptr;
927 size_t nlen;
928
929 if (ph[i].p_type != PT_NOTE ||
930 ph[i].p_filesz > ELF_MAXNOTESIZE)
931 continue;
932
933 nlen = ph[i].p_filesz;
934 error = exec_read(l, epp->ep_vp, ph[i].p_offset, nbuf, nlen,
935 IO_NODELOCKED);
936 if (error)
937 continue;
938
939 nptr = nbuf;
940 while (nlen > 0) {
941 const Elf_Nhdr *np;
942 const char *ndata, *ndesc;
943
944 /* note header */
945 np = (const Elf_Nhdr *)nptr;
946 if (nlen < sizeof(*np)) {
947 break;
948 }
949 nptr += sizeof(*np);
950 nlen -= sizeof(*np);
951
952 /* note name */
953 ndata = nptr;
954 if (nlen < roundup(np->n_namesz, 4)) {
955 break;
956 }
957 nptr += roundup(np->n_namesz, 4);
958 nlen -= roundup(np->n_namesz, 4);
959
960 /* note description */
961 ndesc = nptr;
962 if (nlen < roundup(np->n_descsz, 4)) {
963 break;
964 }
965 nptr += roundup(np->n_descsz, 4);
966 nlen -= roundup(np->n_descsz, 4);
967
968 isnetbsd |= netbsd_elf_note(epp, np, ndata, ndesc);
969 }
970 }
971 kmem_free(nbuf, ELF_MAXNOTESIZE);
972
973 error = isnetbsd ? 0 : SET_ERROR(ENOEXEC);
974 #ifdef DEBUG_ELF
975 if (error)
976 DPRINTF("not netbsd");
977 #endif
978 out:
979 kmem_free(ph, phsize);
980 return error;
981 }
982
983 int
netbsd_elf_note(struct exec_package * epp,const Elf_Nhdr * np,const char * ndata,const char * ndesc)984 netbsd_elf_note(struct exec_package *epp,
985 const Elf_Nhdr *np, const char *ndata, const char *ndesc)
986 {
987 int isnetbsd = 0;
988
989 #ifdef DIAGNOSTIC
990 const char *badnote;
991 #define BADNOTE(n) badnote = (n)
992 #else
993 #define BADNOTE(n)
994 #endif
995
996 switch (np->n_type) {
997 case ELF_NOTE_TYPE_NETBSD_TAG:
998 /* It is us */
999 if (np->n_namesz == ELF_NOTE_NETBSD_NAMESZ &&
1000 np->n_descsz == ELF_NOTE_NETBSD_DESCSZ &&
1001 memcmp(ndata, ELF_NOTE_NETBSD_NAME,
1002 ELF_NOTE_NETBSD_NAMESZ) == 0) {
1003 memcpy(&epp->ep_osversion, ndesc,
1004 ELF_NOTE_NETBSD_DESCSZ);
1005 isnetbsd = 1;
1006 break;
1007 }
1008
1009 /*
1010 * Ignore SuSE tags; SuSE's n_type is the same the
1011 * NetBSD one.
1012 */
1013 if (np->n_namesz == ELF_NOTE_SUSE_NAMESZ &&
1014 memcmp(ndata, ELF_NOTE_SUSE_NAME,
1015 ELF_NOTE_SUSE_NAMESZ) == 0)
1016 break;
1017 /*
1018 * Ignore old GCC
1019 */
1020 if (np->n_namesz == ELF_NOTE_OGCC_NAMESZ &&
1021 memcmp(ndata, ELF_NOTE_OGCC_NAME,
1022 ELF_NOTE_OGCC_NAMESZ) == 0)
1023 break;
1024 BADNOTE("NetBSD tag");
1025 goto bad;
1026
1027 case ELF_NOTE_TYPE_PAX_TAG:
1028 if (np->n_namesz == ELF_NOTE_PAX_NAMESZ &&
1029 np->n_descsz == ELF_NOTE_PAX_DESCSZ &&
1030 memcmp(ndata, ELF_NOTE_PAX_NAME,
1031 ELF_NOTE_PAX_NAMESZ) == 0) {
1032 uint32_t flags;
1033 memcpy(&flags, ndesc, sizeof(flags));
1034 /* Convert the flags and insert them into
1035 * the exec package. */
1036 pax_setup_elf_flags(epp, flags);
1037 break;
1038 }
1039 BADNOTE("PaX tag");
1040 goto bad;
1041
1042 case ELF_NOTE_TYPE_MARCH_TAG:
1043 /* Copy the machine arch into the package. */
1044 if (np->n_namesz == ELF_NOTE_MARCH_NAMESZ
1045 && memcmp(ndata, ELF_NOTE_MARCH_NAME,
1046 ELF_NOTE_MARCH_NAMESZ) == 0) {
1047 /* Do not truncate the buffer */
1048 if (np->n_descsz > sizeof(epp->ep_machine_arch)) {
1049 BADNOTE("description size limit");
1050 goto bad;
1051 }
1052 /*
1053 * Ensure ndesc is NUL-terminated and of the
1054 * expected length.
1055 */
1056 if (strnlen(ndesc, np->n_descsz) + 1 !=
1057 np->n_descsz) {
1058 BADNOTE("description size");
1059 goto bad;
1060 }
1061 strlcpy(epp->ep_machine_arch, ndesc,
1062 sizeof(epp->ep_machine_arch));
1063 break;
1064 }
1065 BADNOTE("march tag");
1066 goto bad;
1067
1068 case ELF_NOTE_TYPE_MCMODEL_TAG:
1069 /* arch specific check for code model */
1070 #ifdef ELF_MD_MCMODEL_CHECK
1071 if (np->n_namesz == ELF_NOTE_MCMODEL_NAMESZ
1072 && memcmp(ndata, ELF_NOTE_MCMODEL_NAME,
1073 ELF_NOTE_MCMODEL_NAMESZ) == 0) {
1074 ELF_MD_MCMODEL_CHECK(epp, ndesc, np->n_descsz);
1075 break;
1076 }
1077 BADNOTE("mcmodel tag");
1078 goto bad;
1079 #endif
1080 break;
1081
1082 case ELF_NOTE_TYPE_SUSE_VERSION_TAG:
1083 break;
1084
1085 case ELF_NOTE_TYPE_GO_BUILDID_TAG:
1086 break;
1087
1088 case ELF_NOTE_TYPE_FDO_PACKAGING_METADATA:
1089 break;
1090
1091 case ELF_NOTE_TYPE_NETBSD_EMUL_TAG:
1092 /* Ancient NetBSD version tag */
1093 break;
1094
1095 default:
1096 BADNOTE("unknown tag");
1097 bad:
1098 #ifdef DIAGNOSTIC
1099 /* Ignore GNU tags */
1100 if (np->n_namesz == ELF_NOTE_GNU_NAMESZ &&
1101 memcmp(ndata, ELF_NOTE_GNU_NAME,
1102 ELF_NOTE_GNU_NAMESZ) == 0)
1103 break;
1104
1105 int ns = (int)np->n_namesz;
1106 printf("%s: Unknown elf note type %d (%s): "
1107 "[namesz=%d, descsz=%d name=%-*.*s]\n",
1108 epp->ep_kname, np->n_type, badnote, np->n_namesz,
1109 np->n_descsz, ns, ns, ndata);
1110 #endif
1111 break;
1112 }
1113
1114 return isnetbsd;
1115 }
1116
1117 int
netbsd_elf_probe(struct lwp * l,struct exec_package * epp,void * eh,char * itp,vaddr_t * pos)1118 netbsd_elf_probe(struct lwp *l, struct exec_package *epp, void *eh, char *itp,
1119 vaddr_t *pos)
1120 {
1121 int error;
1122
1123 if ((error = netbsd_elf_signature(l, epp, eh)) != 0)
1124 return error;
1125 #ifdef ELF_MD_PROBE_FUNC
1126 if ((error = ELF_MD_PROBE_FUNC(l, epp, eh, itp, pos)) != 0)
1127 return error;
1128 #elif defined(ELF_INTERP_NON_RELOCATABLE)
1129 *pos = ELF_LINK_ADDR;
1130 #endif
1131 epp->ep_flags |= EXEC_FORCEAUX;
1132 return 0;
1133 }
1134
1135 void
elf_free_emul_arg(void * arg)1136 elf_free_emul_arg(void *arg)
1137 {
1138 struct elf_args *ap = arg;
1139 KASSERT(ap != NULL);
1140 kmem_free(ap, sizeof(*ap));
1141 }
1142