Initial import from FreeBSD RELENG_4:
[dragonfly.git] / sys / kern / kern_exec.c
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1/*
2 * Copyright (c) 1993, David Greenman
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: src/sys/kern/kern_exec.c,v 1.107.2.15 2002/07/30 15:40:46 nectar Exp $
27 */
28
29#include <sys/param.h>
30#include <sys/systm.h>
31#include <sys/sysproto.h>
32#include <sys/kernel.h>
33#include <sys/mount.h>
34#include <sys/filedesc.h>
35#include <sys/fcntl.h>
36#include <sys/acct.h>
37#include <sys/exec.h>
38#include <sys/imgact.h>
39#include <sys/imgact_elf.h>
40#include <sys/wait.h>
41#include <sys/malloc.h>
42#include <sys/proc.h>
43#include <sys/signalvar.h>
44#include <sys/pioctl.h>
45#include <sys/namei.h>
46#include <sys/sysent.h>
47#include <sys/shm.h>
48#include <sys/sysctl.h>
49#include <sys/vnode.h>
50#include <sys/aio.h>
51
52#include <vm/vm.h>
53#include <vm/vm_param.h>
54#include <sys/lock.h>
55#include <vm/pmap.h>
56#include <vm/vm_page.h>
57#include <vm/vm_map.h>
58#include <vm/vm_kern.h>
59#include <vm/vm_extern.h>
60#include <vm/vm_object.h>
61#include <vm/vm_pager.h>
62
63#include <sys/user.h>
64#include <machine/reg.h>
65
66MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments");
67
68static register_t *exec_copyout_strings __P((struct image_params *));
69
70/* XXX This should be vm_size_t. */
71static u_long ps_strings = PS_STRINGS;
72SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, "");
73
74/* XXX This should be vm_size_t. */
75static u_long usrstack = USRSTACK;
76SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, "");
77
78u_long ps_arg_cache_limit = PAGE_SIZE / 16;
79SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW,
80 &ps_arg_cache_limit, 0, "");
81
82int ps_argsopen = 1;
83SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, "");
84
85/*
86 * Each of the items is a pointer to a `const struct execsw', hence the
87 * double pointer here.
88 */
89static const struct execsw **execsw;
90
91#ifndef _SYS_SYSPROTO_H_
92struct execve_args {
93 char *fname;
94 char **argv;
95 char **envv;
96};
97#endif
98
99/*
100 * execve() system call.
101 */
102int
103execve(p, uap)
104 struct proc *p;
105 register struct execve_args *uap;
106{
107 struct nameidata nd, *ndp;
108 register_t *stack_base;
109 int error, len, i;
110 struct image_params image_params, *imgp;
111 struct vattr attr;
112 int (*img_first) __P((struct image_params *));
113
114 imgp = &image_params;
115
116 /*
117 * Lock the process and set the P_INEXEC flag to indicate that
118 * it should be left alone until we're done here. This is
119 * necessary to avoid race conditions - e.g. in ptrace() -
120 * that might allow a local user to illicitly obtain elevated
121 * privileges.
122 */
123 p->p_flag |= P_INEXEC;
124
125 /*
126 * Initialize part of the common data
127 */
128 imgp->proc = p;
129 imgp->uap = uap;
130 imgp->attr = &attr;
131 imgp->argc = imgp->envc = 0;
132 imgp->argv0 = NULL;
133 imgp->entry_addr = 0;
134 imgp->vmspace_destroyed = 0;
135 imgp->interpreted = 0;
136 imgp->interpreter_name[0] = '\0';
137 imgp->auxargs = NULL;
138 imgp->vp = NULL;
139 imgp->firstpage = NULL;
140 imgp->ps_strings = 0;
141
142 /*
143 * Allocate temporary demand zeroed space for argument and
144 * environment strings
145 */
146 imgp->stringbase = (char *)kmem_alloc_wait(exec_map, ARG_MAX + PAGE_SIZE);
147 if (imgp->stringbase == NULL) {
148 error = ENOMEM;
149 goto exec_fail;
150 }
151 imgp->stringp = imgp->stringbase;
152 imgp->stringspace = ARG_MAX;
153 imgp->image_header = imgp->stringbase + ARG_MAX;
154
155 /*
156 * Translate the file name. namei() returns a vnode pointer
157 * in ni_vp amoung other things.
158 */
159 ndp = &nd;
160 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME,
161 UIO_USERSPACE, uap->fname, p);
162
163interpret:
164
165 error = namei(ndp);
166 if (error) {
167 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase,
168 ARG_MAX + PAGE_SIZE);
169 goto exec_fail;
170 }
171
172 imgp->vp = ndp->ni_vp;
173 imgp->fname = uap->fname;
174
175 /*
176 * Check file permissions (also 'opens' file)
177 */
178 error = exec_check_permissions(imgp);
179 if (error) {
180 VOP_UNLOCK(imgp->vp, 0, p);
181 goto exec_fail_dealloc;
182 }
183
184 error = exec_map_first_page(imgp);
185 VOP_UNLOCK(imgp->vp, 0, p);
186 if (error)
187 goto exec_fail_dealloc;
188
189 /*
190 * If the current process has a special image activator it
191 * wants to try first, call it. For example, emulating shell
192 * scripts differently.
193 */
194 error = -1;
195 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL)
196 error = img_first(imgp);
197
198 /*
199 * Loop through the list of image activators, calling each one.
200 * An activator returns -1 if there is no match, 0 on success,
201 * and an error otherwise.
202 */
203 for (i = 0; error == -1 && execsw[i]; ++i) {
204 if (execsw[i]->ex_imgact == NULL ||
205 execsw[i]->ex_imgact == img_first) {
206 continue;
207 }
208 error = (*execsw[i]->ex_imgact)(imgp);
209 }
210
211 if (error) {
212 if (error == -1)
213 error = ENOEXEC;
214 goto exec_fail_dealloc;
215 }
216
217 /*
218 * Special interpreter operation, cleanup and loop up to try to
219 * activate the interpreter.
220 */
221 if (imgp->interpreted) {
222 exec_unmap_first_page(imgp);
223 /* free name buffer and old vnode */
224 NDFREE(ndp, NDF_ONLY_PNBUF);
225 vrele(ndp->ni_vp);
226 /* set new name to that of the interpreter */
227 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME,
228 UIO_SYSSPACE, imgp->interpreter_name, p);
229 goto interpret;
230 }
231
232 /*
233 * Copy out strings (args and env) and initialize stack base
234 */
235 stack_base = exec_copyout_strings(imgp);
236 p->p_vmspace->vm_minsaddr = (char *)stack_base;
237
238 /*
239 * If custom stack fixup routine present for this process
240 * let it do the stack setup.
241 * Else stuff argument count as first item on stack
242 */
243 if (p->p_sysent->sv_fixup)
244 (*p->p_sysent->sv_fixup)(&stack_base, imgp);
245 else
246 suword(--stack_base, imgp->argc);
247
248 /*
249 * For security and other reasons, the file descriptor table cannot
250 * be shared after an exec.
251 */
252 if (p->p_fd->fd_refcnt > 1) {
253 struct filedesc *tmp;
254
255 tmp = fdcopy(p);
256 fdfree(p);
257 p->p_fd = tmp;
258 }
259
260 /*
261 * For security and other reasons, signal handlers cannot
262 * be shared after an exec. The new proces gets a copy of the old
263 * handlers. In execsigs(), the new process will have its signals
264 * reset.
265 */
266 if (p->p_procsig->ps_refcnt > 1) {
267 struct procsig *newprocsig;
268
269 MALLOC(newprocsig, struct procsig *, sizeof(struct procsig),
270 M_SUBPROC, M_WAITOK);
271 bcopy(p->p_procsig, newprocsig, sizeof(*newprocsig));
272 p->p_procsig->ps_refcnt--;
273 p->p_procsig = newprocsig;
274 p->p_procsig->ps_refcnt = 1;
275 if (p->p_sigacts == &p->p_addr->u_sigacts)
276 panic("shared procsig but private sigacts?");
277
278 p->p_addr->u_sigacts = *p->p_sigacts;
279 p->p_sigacts = &p->p_addr->u_sigacts;
280 }
281
282 /* Stop profiling */
283 stopprofclock(p);
284
285 /* close files on exec */
286 fdcloseexec(p);
287
288 /* reset caught signals */
289 execsigs(p);
290
291 /* name this process - nameiexec(p, ndp) */
292 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN);
293 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len);
294 p->p_comm[len] = 0;
295
296 /*
297 * mark as execed, wakeup the process that vforked (if any) and tell
298 * it that it now has its own resources back
299 */
300 p->p_flag |= P_EXEC;
301 if (p->p_pptr && (p->p_flag & P_PPWAIT)) {
302 p->p_flag &= ~P_PPWAIT;
303 wakeup((caddr_t)p->p_pptr);
304 }
305
306 /*
307 * Implement image setuid/setgid.
308 *
309 * Don't honor setuid/setgid if the filesystem prohibits it or if
310 * the process is being traced.
311 */
312 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) ||
313 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) &&
314 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 &&
315 (p->p_flag & P_TRACED) == 0) {
316 /*
317 * Turn off syscall tracing for set-id programs, except for
318 * root. Record any set-id flags first to make sure that
319 * we do not regain any tracing during a possible block.
320 */
321 setsugid(p);
322 if (p->p_tracep && suser(p)) {
323 struct vnode *vtmp;
324
325 if ((vtmp = p->p_tracep) != NULL) {
326 p->p_tracep = NULL;
327 p->p_traceflag = 0;
328 vrele(vtmp);
329 }
330 }
331 /* Close any file descriptors 0..2 that reference procfs */
332 setugidsafety(p);
333 /* Make sure file descriptors 0..2 are in use. */
334 error = fdcheckstd(p);
335 if (error != 0)
336 goto exec_fail_dealloc;
337 /*
338 * Set the new credentials.
339 */
340 p->p_ucred = crcopy(p->p_ucred);
341 if (attr.va_mode & VSUID)
342 change_euid(p, attr.va_uid);
343 if (attr.va_mode & VSGID)
344 p->p_ucred->cr_gid = attr.va_gid;
345 } else {
346 if (p->p_ucred->cr_uid == p->p_cred->p_ruid &&
347 p->p_ucred->cr_gid == p->p_cred->p_rgid)
348 p->p_flag &= ~P_SUGID;
349 }
350
351 /*
352 * Implement correct POSIX saved-id behavior.
353 */
354 p->p_cred->p_svuid = p->p_ucred->cr_uid;
355 p->p_cred->p_svgid = p->p_ucred->cr_gid;
356
357 /*
358 * Store the vp for use in procfs
359 */
360 if (p->p_textvp) /* release old reference */
361 vrele(p->p_textvp);
362 VREF(ndp->ni_vp);
363 p->p_textvp = ndp->ni_vp;
364
365 /*
366 * Notify others that we exec'd, and clear the P_INEXEC flag
367 * as we're now a bona fide freshly-execed process.
368 */
369 KNOTE(&p->p_klist, NOTE_EXEC);
370 p->p_flag &= ~P_INEXEC;
371
372 /*
373 * If tracing the process, trap to debugger so breakpoints
374 * can be set before the program executes.
375 */
376 STOPEVENT(p, S_EXEC, 0);
377
378 if (p->p_flag & P_TRACED)
379 psignal(p, SIGTRAP);
380
381 /* clear "fork but no exec" flag, as we _are_ execing */
382 p->p_acflag &= ~AFORK;
383
384 /* Set values passed into the program in registers. */
385 setregs(p, imgp->entry_addr, (u_long)(uintptr_t)stack_base,
386 imgp->ps_strings);
387
388 /* Free any previous argument cache */
389 if (p->p_args && --p->p_args->ar_ref == 0)
390 FREE(p->p_args, M_PARGS);
391 p->p_args = NULL;
392
393 /* Cache arguments if they fit inside our allowance */
394 i = imgp->endargs - imgp->stringbase;
395 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) {
396 MALLOC(p->p_args, struct pargs *, sizeof(struct pargs) + i,
397 M_PARGS, M_WAITOK);
398 p->p_args->ar_ref = 1;
399 p->p_args->ar_length = i;
400 bcopy(imgp->stringbase, p->p_args->ar_args, i);
401 }
402
403exec_fail_dealloc:
404
405 /*
406 * free various allocated resources
407 */
408 if (imgp->firstpage)
409 exec_unmap_first_page(imgp);
410
411 if (imgp->stringbase != NULL)
412 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase,
413 ARG_MAX + PAGE_SIZE);
414
415 if (imgp->vp) {
416 NDFREE(ndp, NDF_ONLY_PNBUF);
417 vrele(imgp->vp);
418 }
419
420 if (error == 0)
421 return (0);
422
423exec_fail:
424 /* we're done here, clear P_INEXEC */
425 p->p_flag &= ~P_INEXEC;
426 if (imgp->vmspace_destroyed) {
427 /* sorry, no more process anymore. exit gracefully */
428 exit1(p, W_EXITCODE(0, SIGABRT));
429 /* NOT REACHED */
430 return(0);
431 } else {
432 return(error);
433 }
434}
435
436int
437exec_map_first_page(imgp)
438 struct image_params *imgp;
439{
440 int s, rv, i;
441 int initial_pagein;
442 vm_page_t ma[VM_INITIAL_PAGEIN];
443 vm_object_t object;
444
445
446 if (imgp->firstpage) {
447 exec_unmap_first_page(imgp);
448 }
449
450 VOP_GETVOBJECT(imgp->vp, &object);
451 s = splvm();
452
453 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
454
455 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) {
456 initial_pagein = VM_INITIAL_PAGEIN;
457 if (initial_pagein > object->size)
458 initial_pagein = object->size;
459 for (i = 1; i < initial_pagein; i++) {
460 if ((ma[i] = vm_page_lookup(object, i)) != NULL) {
461 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy)
462 break;
463 if (ma[i]->valid)
464 break;
465 vm_page_busy(ma[i]);
466 } else {
467 ma[i] = vm_page_alloc(object, i, VM_ALLOC_NORMAL);
468 if (ma[i] == NULL)
469 break;
470 }
471 }
472 initial_pagein = i;
473
474 rv = vm_pager_get_pages(object, ma, initial_pagein, 0);
475 ma[0] = vm_page_lookup(object, 0);
476
477 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || (ma[0]->valid == 0)) {
478 if (ma[0]) {
479 vm_page_protect(ma[0], VM_PROT_NONE);
480 vm_page_free(ma[0]);
481 }
482 splx(s);
483 return EIO;
484 }
485 }
486
487 vm_page_wire(ma[0]);
488 vm_page_wakeup(ma[0]);
489 splx(s);
490
491 pmap_kenter((vm_offset_t) imgp->image_header, VM_PAGE_TO_PHYS(ma[0]));
492 imgp->firstpage = ma[0];
493
494 return 0;
495}
496
497void
498exec_unmap_first_page(imgp)
499 struct image_params *imgp;
500{
501 if (imgp->firstpage) {
502 pmap_kremove((vm_offset_t) imgp->image_header);
503 vm_page_unwire(imgp->firstpage, 1);
504 imgp->firstpage = NULL;
505 }
506}
507
508/*
509 * Destroy old address space, and allocate a new stack
510 * The new stack is only SGROWSIZ large because it is grown
511 * automatically in trap.c.
512 */
513int
514exec_new_vmspace(imgp)
515 struct image_params *imgp;
516{
517 int error;
518 struct vmspace *vmspace = imgp->proc->p_vmspace;
519 vm_offset_t stack_addr = USRSTACK - maxssiz;
520 vm_map_t map = &vmspace->vm_map;
521
522 imgp->vmspace_destroyed = 1;
523
524 /*
525 * Prevent a pending AIO from modifying the new address space.
526 */
527 aio_proc_rundown(imgp->proc);
528
529 /*
530 * Blow away entire process VM, if address space not shared,
531 * otherwise, create a new VM space so that other threads are
532 * not disrupted
533 */
534 if (vmspace->vm_refcnt == 1) {
535 if (vmspace->vm_shm)
536 shmexit(imgp->proc);
537 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS);
538 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS);
539 } else {
540 vmspace_exec(imgp->proc);
541 vmspace = imgp->proc->p_vmspace;
542 map = &vmspace->vm_map;
543 }
544
545 /* Allocate a new stack */
546 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz,
547 VM_PROT_ALL, VM_PROT_ALL, 0);
548 if (error)
549 return (error);
550
551 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the
552 * VM_STACK case, but they are still used to monitor the size of the
553 * process stack so we can check the stack rlimit.
554 */
555 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT;
556 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz;
557
558 return(0);
559}
560
561/*
562 * Copy out argument and environment strings from the old process
563 * address space into the temporary string buffer.
564 */
565int
566exec_extract_strings(imgp)
567 struct image_params *imgp;
568{
569 char **argv, **envv;
570 char *argp, *envp;
571 int error;
572 size_t length;
573
574 /*
575 * extract arguments first
576 */
577
578 argv = imgp->uap->argv;
579
580 if (argv) {
581 argp = (caddr_t) (intptr_t) fuword(argv);
582 if (argp == (caddr_t) -1)
583 return (EFAULT);
584 if (argp)
585 argv++;
586 if (imgp->argv0)
587 argp = imgp->argv0;
588 if (argp) {
589 do {
590 if (argp == (caddr_t) -1)
591 return (EFAULT);
592 if ((error = copyinstr(argp, imgp->stringp,
593 imgp->stringspace, &length))) {
594 if (error == ENAMETOOLONG)
595 return(E2BIG);
596 return (error);
597 }
598 imgp->stringspace -= length;
599 imgp->stringp += length;
600 imgp->argc++;
601 } while ((argp = (caddr_t) (intptr_t) fuword(argv++)));
602 }
603 }
604
605 imgp->endargs = imgp->stringp;
606
607 /*
608 * extract environment strings
609 */
610
611 envv = imgp->uap->envv;
612
613 if (envv) {
614 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) {
615 if (envp == (caddr_t) -1)
616 return (EFAULT);
617 if ((error = copyinstr(envp, imgp->stringp,
618 imgp->stringspace, &length))) {
619 if (error == ENAMETOOLONG)
620 return(E2BIG);
621 return (error);
622 }
623 imgp->stringspace -= length;
624 imgp->stringp += length;
625 imgp->envc++;
626 }
627 }
628
629 return (0);
630}
631
632/*
633 * Copy strings out to the new process address space, constructing
634 * new arg and env vector tables. Return a pointer to the base
635 * so that it can be used as the initial stack pointer.
636 */
637register_t *
638exec_copyout_strings(imgp)
639 struct image_params *imgp;
640{
641 int argc, envc;
642 char **vectp;
643 char *stringp, *destp;
644 register_t *stack_base;
645 struct ps_strings *arginfo;
646 int szsigcode;
647
648 /*
649 * Calculate string base and vector table pointers.
650 * Also deal with signal trampoline code for this exec type.
651 */
652 arginfo = (struct ps_strings *)PS_STRINGS;
653 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode);
654 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE -
655 roundup((ARG_MAX - imgp->stringspace), sizeof(char *));
656
657 /*
658 * install sigcode
659 */
660 if (szsigcode)
661 copyout(imgp->proc->p_sysent->sv_sigcode,
662 ((caddr_t)arginfo - szsigcode), szsigcode);
663
664 /*
665 * If we have a valid auxargs ptr, prepare some room
666 * on the stack.
667 */
668 if (imgp->auxargs)
669 /*
670 * The '+ 2' is for the null pointers at the end of each of the
671 * arg and env vector sets, and 'AT_COUNT*2' is room for the
672 * ELF Auxargs data.
673 */
674 vectp = (char **)(destp - (imgp->argc + imgp->envc + 2 +
675 AT_COUNT*2) * sizeof(char*));
676 else
677 /*
678 * The '+ 2' is for the null pointers at the end of each of the
679 * arg and env vector sets
680 */
681 vectp = (char **)
682 (destp - (imgp->argc + imgp->envc + 2) * sizeof(char*));
683
684 /*
685 * vectp also becomes our initial stack base
686 */
687 stack_base = (register_t *)vectp;
688
689 stringp = imgp->stringbase;
690 argc = imgp->argc;
691 envc = imgp->envc;
692
693 /*
694 * Copy out strings - arguments and environment.
695 */
696 copyout(stringp, destp, ARG_MAX - imgp->stringspace);
697
698 /*
699 * Fill in "ps_strings" struct for ps, w, etc.
700 */
701 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp);
702 suword(&arginfo->ps_nargvstr, argc);
703
704 /*
705 * Fill in argument portion of vector table.
706 */
707 for (; argc > 0; --argc) {
708 suword(vectp++, (long)(intptr_t)destp);
709 while (*stringp++ != 0)
710 destp++;
711 destp++;
712 }
713
714 /* a null vector table pointer seperates the argp's from the envp's */
715 suword(vectp++, 0);
716
717 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp);
718 suword(&arginfo->ps_nenvstr, envc);
719
720 /*
721 * Fill in environment portion of vector table.
722 */
723 for (; envc > 0; --envc) {
724 suword(vectp++, (long)(intptr_t)destp);
725 while (*stringp++ != 0)
726 destp++;
727 destp++;
728 }
729
730 /* end of vector table is a null pointer */
731 suword(vectp, 0);
732
733 return (stack_base);
734}
735
736/*
737 * Check permissions of file to execute.
738 * Return 0 for success or error code on failure.
739 */
740int
741exec_check_permissions(imgp)
742 struct image_params *imgp;
743{
744 struct proc *p = imgp->proc;
745 struct vnode *vp = imgp->vp;
746 struct vattr *attr = imgp->attr;
747 int error;
748
749 /* Get file attributes */
750 error = VOP_GETATTR(vp, attr, p->p_ucred, p);
751 if (error)
752 return (error);
753
754 /*
755 * 1) Check if file execution is disabled for the filesystem that this
756 * file resides on.
757 * 2) Insure that at least one execute bit is on - otherwise root
758 * will always succeed, and we don't want to happen unless the
759 * file really is executable.
760 * 3) Insure that the file is a regular file.
761 */
762 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) ||
763 ((attr->va_mode & 0111) == 0) ||
764 (attr->va_type != VREG)) {
765 return (EACCES);
766 }
767
768 /*
769 * Zero length files can't be exec'd
770 */
771 if (attr->va_size == 0)
772 return (ENOEXEC);
773
774 /*
775 * Check for execute permission to file based on current credentials.
776 */
777 error = VOP_ACCESS(vp, VEXEC, p->p_ucred, p);
778 if (error)
779 return (error);
780
781 /*
782 * Check number of open-for-writes on the file and deny execution
783 * if there are any.
784 */
785 if (vp->v_writecount)
786 return (ETXTBSY);
787
788 /*
789 * Call filesystem specific open routine (which does nothing in the
790 * general case).
791 */
792 error = VOP_OPEN(vp, FREAD, p->p_ucred, p);
793 if (error)
794 return (error);
795
796 return (0);
797}
798
799/*
800 * Exec handler registration
801 */
802int
803exec_register(execsw_arg)
804 const struct execsw *execsw_arg;
805{
806 const struct execsw **es, **xs, **newexecsw;
807 int count = 2; /* New slot and trailing NULL */
808
809 if (execsw)
810 for (es = execsw; *es; es++)
811 count++;
812 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
813 if (newexecsw == NULL)
814 return ENOMEM;
815 xs = newexecsw;
816 if (execsw)
817 for (es = execsw; *es; es++)
818 *xs++ = *es;
819 *xs++ = execsw_arg;
820 *xs = NULL;
821 if (execsw)
822 free(execsw, M_TEMP);
823 execsw = newexecsw;
824 return 0;
825}
826
827int
828exec_unregister(execsw_arg)
829 const struct execsw *execsw_arg;
830{
831 const struct execsw **es, **xs, **newexecsw;
832 int count = 1;
833
834 if (execsw == NULL)
835 panic("unregister with no handlers left?\n");
836
837 for (es = execsw; *es; es++) {
838 if (*es == execsw_arg)
839 break;
840 }
841 if (*es == NULL)
842 return ENOENT;
843 for (es = execsw; *es; es++)
844 if (*es != execsw_arg)
845 count++;
846 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
847 if (newexecsw == NULL)
848 return ENOMEM;
849 xs = newexecsw;
850 for (es = execsw; *es; es++)
851 if (*es != execsw_arg)
852 *xs++ = *es;
853 *xs = NULL;
854 if (execsw)
855 free(execsw, M_TEMP);
856 execsw = newexecsw;
857 return 0;
858}