Fix a problem that occurs when truncating files on NFSv3 mounts: we need
[dragonfly.git] / sys / kern / kern_exec.c
CommitLineData
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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 $
a64ba182 27 * $DragonFly: src/sys/kern/kern_exec.c,v 1.8 2003/07/24 01:41:25 dillon Exp $
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28 */
29
30#include <sys/param.h>
31#include <sys/systm.h>
32#include <sys/sysproto.h>
33#include <sys/kernel.h>
34#include <sys/mount.h>
35#include <sys/filedesc.h>
36#include <sys/fcntl.h>
37#include <sys/acct.h>
38#include <sys/exec.h>
39#include <sys/imgact.h>
40#include <sys/imgact_elf.h>
41#include <sys/wait.h>
42#include <sys/malloc.h>
43#include <sys/proc.h>
44#include <sys/signalvar.h>
45#include <sys/pioctl.h>
46#include <sys/namei.h>
47#include <sys/sysent.h>
48#include <sys/shm.h>
49#include <sys/sysctl.h>
50#include <sys/vnode.h>
51#include <sys/aio.h>
52
53#include <vm/vm.h>
54#include <vm/vm_param.h>
55#include <sys/lock.h>
56#include <vm/pmap.h>
57#include <vm/vm_page.h>
58#include <vm/vm_map.h>
59#include <vm/vm_kern.h>
60#include <vm/vm_extern.h>
61#include <vm/vm_object.h>
62#include <vm/vm_pager.h>
63
64#include <sys/user.h>
65#include <machine/reg.h>
66
67MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments");
68
69static register_t *exec_copyout_strings __P((struct image_params *));
70
71/* XXX This should be vm_size_t. */
72static u_long ps_strings = PS_STRINGS;
73SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, "");
74
75/* XXX This should be vm_size_t. */
76static u_long usrstack = USRSTACK;
77SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, "");
78
79u_long ps_arg_cache_limit = PAGE_SIZE / 16;
80SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW,
81 &ps_arg_cache_limit, 0, "");
82
83int ps_argsopen = 1;
84SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, "");
85
86/*
87 * Each of the items is a pointer to a `const struct execsw', hence the
88 * double pointer here.
89 */
90static const struct execsw **execsw;
91
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92/*
93 * execve() system call.
94 */
95int
41c20dac 96execve(struct execve_args *uap)
984263bc 97{
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98 struct thread *td = curthread;
99 struct proc *p = td->td_proc;
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100 struct nameidata nd, *ndp;
101 register_t *stack_base;
102 int error, len, i;
103 struct image_params image_params, *imgp;
104 struct vattr attr;
105 int (*img_first) __P((struct image_params *));
106
dadab5e9 107 KKASSERT(p);
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108 imgp = &image_params;
109
110 /*
111 * Lock the process and set the P_INEXEC flag to indicate that
112 * it should be left alone until we're done here. This is
113 * necessary to avoid race conditions - e.g. in ptrace() -
114 * that might allow a local user to illicitly obtain elevated
115 * privileges.
116 */
117 p->p_flag |= P_INEXEC;
118
119 /*
120 * Initialize part of the common data
121 */
122 imgp->proc = p;
123 imgp->uap = uap;
124 imgp->attr = &attr;
125 imgp->argc = imgp->envc = 0;
126 imgp->argv0 = NULL;
127 imgp->entry_addr = 0;
128 imgp->vmspace_destroyed = 0;
129 imgp->interpreted = 0;
130 imgp->interpreter_name[0] = '\0';
131 imgp->auxargs = NULL;
132 imgp->vp = NULL;
133 imgp->firstpage = NULL;
134 imgp->ps_strings = 0;
135
136 /*
137 * Allocate temporary demand zeroed space for argument and
138 * environment strings
139 */
140 imgp->stringbase = (char *)kmem_alloc_wait(exec_map, ARG_MAX + PAGE_SIZE);
141 if (imgp->stringbase == NULL) {
142 error = ENOMEM;
143 goto exec_fail;
144 }
145 imgp->stringp = imgp->stringbase;
146 imgp->stringspace = ARG_MAX;
147 imgp->image_header = imgp->stringbase + ARG_MAX;
148
149 /*
150 * Translate the file name. namei() returns a vnode pointer
151 * in ni_vp amoung other things.
152 */
153 ndp = &nd;
154 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME,
dadab5e9 155 UIO_USERSPACE, uap->fname, td);
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156
157interpret:
158
159 error = namei(ndp);
160 if (error) {
161 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase,
162 ARG_MAX + PAGE_SIZE);
163 goto exec_fail;
164 }
165
166 imgp->vp = ndp->ni_vp;
167 imgp->fname = uap->fname;
168
169 /*
170 * Check file permissions (also 'opens' file)
171 */
172 error = exec_check_permissions(imgp);
173 if (error) {
dadab5e9 174 VOP_UNLOCK(imgp->vp, 0, td);
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175 goto exec_fail_dealloc;
176 }
177
178 error = exec_map_first_page(imgp);
dadab5e9 179 VOP_UNLOCK(imgp->vp, 0, td);
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180 if (error)
181 goto exec_fail_dealloc;
182
183 /*
184 * If the current process has a special image activator it
185 * wants to try first, call it. For example, emulating shell
186 * scripts differently.
187 */
188 error = -1;
189 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL)
190 error = img_first(imgp);
191
192 /*
193 * Loop through the list of image activators, calling each one.
194 * An activator returns -1 if there is no match, 0 on success,
195 * and an error otherwise.
196 */
197 for (i = 0; error == -1 && execsw[i]; ++i) {
198 if (execsw[i]->ex_imgact == NULL ||
199 execsw[i]->ex_imgact == img_first) {
200 continue;
201 }
202 error = (*execsw[i]->ex_imgact)(imgp);
203 }
204
205 if (error) {
206 if (error == -1)
207 error = ENOEXEC;
208 goto exec_fail_dealloc;
209 }
210
211 /*
212 * Special interpreter operation, cleanup and loop up to try to
213 * activate the interpreter.
214 */
215 if (imgp->interpreted) {
216 exec_unmap_first_page(imgp);
217 /* free name buffer and old vnode */
218 NDFREE(ndp, NDF_ONLY_PNBUF);
219 vrele(ndp->ni_vp);
220 /* set new name to that of the interpreter */
221 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME,
dadab5e9 222 UIO_SYSSPACE, imgp->interpreter_name, td);
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223 goto interpret;
224 }
225
226 /*
227 * Copy out strings (args and env) and initialize stack base
228 */
229 stack_base = exec_copyout_strings(imgp);
230 p->p_vmspace->vm_minsaddr = (char *)stack_base;
231
232 /*
233 * If custom stack fixup routine present for this process
234 * let it do the stack setup.
235 * Else stuff argument count as first item on stack
236 */
237 if (p->p_sysent->sv_fixup)
238 (*p->p_sysent->sv_fixup)(&stack_base, imgp);
239 else
240 suword(--stack_base, imgp->argc);
241
242 /*
243 * For security and other reasons, the file descriptor table cannot
244 * be shared after an exec.
245 */
246 if (p->p_fd->fd_refcnt > 1) {
247 struct filedesc *tmp;
248
249 tmp = fdcopy(p);
250 fdfree(p);
251 p->p_fd = tmp;
252 }
253
254 /*
255 * For security and other reasons, signal handlers cannot
256 * be shared after an exec. The new proces gets a copy of the old
257 * handlers. In execsigs(), the new process will have its signals
258 * reset.
259 */
260 if (p->p_procsig->ps_refcnt > 1) {
261 struct procsig *newprocsig;
262
263 MALLOC(newprocsig, struct procsig *, sizeof(struct procsig),
264 M_SUBPROC, M_WAITOK);
265 bcopy(p->p_procsig, newprocsig, sizeof(*newprocsig));
266 p->p_procsig->ps_refcnt--;
267 p->p_procsig = newprocsig;
268 p->p_procsig->ps_refcnt = 1;
269 if (p->p_sigacts == &p->p_addr->u_sigacts)
270 panic("shared procsig but private sigacts?");
271
272 p->p_addr->u_sigacts = *p->p_sigacts;
273 p->p_sigacts = &p->p_addr->u_sigacts;
274 }
275
276 /* Stop profiling */
277 stopprofclock(p);
278
279 /* close files on exec */
280 fdcloseexec(p);
281
282 /* reset caught signals */
283 execsigs(p);
284
285 /* name this process - nameiexec(p, ndp) */
286 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN);
287 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len);
288 p->p_comm[len] = 0;
289
290 /*
291 * mark as execed, wakeup the process that vforked (if any) and tell
292 * it that it now has its own resources back
293 */
294 p->p_flag |= P_EXEC;
295 if (p->p_pptr && (p->p_flag & P_PPWAIT)) {
296 p->p_flag &= ~P_PPWAIT;
297 wakeup((caddr_t)p->p_pptr);
298 }
299
300 /*
301 * Implement image setuid/setgid.
302 *
303 * Don't honor setuid/setgid if the filesystem prohibits it or if
304 * the process is being traced.
305 */
306 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) ||
307 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) &&
308 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 &&
309 (p->p_flag & P_TRACED) == 0) {
310 /*
311 * Turn off syscall tracing for set-id programs, except for
312 * root. Record any set-id flags first to make sure that
313 * we do not regain any tracing during a possible block.
314 */
41c20dac 315 setsugid();
dadab5e9 316 if (p->p_tracep && suser(td)) {
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317 struct vnode *vtmp;
318
319 if ((vtmp = p->p_tracep) != NULL) {
320 p->p_tracep = NULL;
321 p->p_traceflag = 0;
322 vrele(vtmp);
323 }
324 }
325 /* Close any file descriptors 0..2 that reference procfs */
326 setugidsafety(p);
327 /* Make sure file descriptors 0..2 are in use. */
328 error = fdcheckstd(p);
329 if (error != 0)
330 goto exec_fail_dealloc;
331 /*
332 * Set the new credentials.
333 */
e9a372eb 334 cratom(&p->p_ucred);
984263bc 335 if (attr.va_mode & VSUID)
41c20dac 336 change_euid(attr.va_uid);
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337 if (attr.va_mode & VSGID)
338 p->p_ucred->cr_gid = attr.va_gid;
339 } else {
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340 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid &&
341 p->p_ucred->cr_gid == p->p_ucred->cr_rgid)
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342 p->p_flag &= ~P_SUGID;
343 }
344
345 /*
346 * Implement correct POSIX saved-id behavior.
347 */
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348 p->p_ucred->cr_svuid = p->p_ucred->cr_uid;
349 p->p_ucred->cr_svgid = p->p_ucred->cr_gid;
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350
351 /*
352 * Store the vp for use in procfs
353 */
354 if (p->p_textvp) /* release old reference */
355 vrele(p->p_textvp);
356 VREF(ndp->ni_vp);
357 p->p_textvp = ndp->ni_vp;
358
359 /*
360 * Notify others that we exec'd, and clear the P_INEXEC flag
361 * as we're now a bona fide freshly-execed process.
362 */
363 KNOTE(&p->p_klist, NOTE_EXEC);
364 p->p_flag &= ~P_INEXEC;
365
366 /*
367 * If tracing the process, trap to debugger so breakpoints
368 * can be set before the program executes.
369 */
370 STOPEVENT(p, S_EXEC, 0);
371
372 if (p->p_flag & P_TRACED)
373 psignal(p, SIGTRAP);
374
375 /* clear "fork but no exec" flag, as we _are_ execing */
376 p->p_acflag &= ~AFORK;
377
378 /* Set values passed into the program in registers. */
379 setregs(p, imgp->entry_addr, (u_long)(uintptr_t)stack_base,
380 imgp->ps_strings);
381
382 /* Free any previous argument cache */
383 if (p->p_args && --p->p_args->ar_ref == 0)
384 FREE(p->p_args, M_PARGS);
385 p->p_args = NULL;
386
387 /* Cache arguments if they fit inside our allowance */
388 i = imgp->endargs - imgp->stringbase;
389 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) {
390 MALLOC(p->p_args, struct pargs *, sizeof(struct pargs) + i,
391 M_PARGS, M_WAITOK);
392 p->p_args->ar_ref = 1;
393 p->p_args->ar_length = i;
394 bcopy(imgp->stringbase, p->p_args->ar_args, i);
395 }
396
397exec_fail_dealloc:
398
399 /*
400 * free various allocated resources
401 */
402 if (imgp->firstpage)
403 exec_unmap_first_page(imgp);
404
405 if (imgp->stringbase != NULL)
406 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase,
407 ARG_MAX + PAGE_SIZE);
408
409 if (imgp->vp) {
410 NDFREE(ndp, NDF_ONLY_PNBUF);
411 vrele(imgp->vp);
412 }
413
414 if (error == 0)
415 return (0);
416
417exec_fail:
418 /* we're done here, clear P_INEXEC */
419 p->p_flag &= ~P_INEXEC;
420 if (imgp->vmspace_destroyed) {
421 /* sorry, no more process anymore. exit gracefully */
41c20dac 422 exit1(W_EXITCODE(0, SIGABRT));
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423 /* NOT REACHED */
424 return(0);
425 } else {
426 return(error);
427 }
428}
429
430int
41c20dac 431exec_map_first_page(struct image_params *imgp)
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432{
433 int s, rv, i;
434 int initial_pagein;
435 vm_page_t ma[VM_INITIAL_PAGEIN];
436 vm_object_t object;
437
438
439 if (imgp->firstpage) {
440 exec_unmap_first_page(imgp);
441 }
442
443 VOP_GETVOBJECT(imgp->vp, &object);
444 s = splvm();
445
446 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
447
448 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) {
449 initial_pagein = VM_INITIAL_PAGEIN;
450 if (initial_pagein > object->size)
451 initial_pagein = object->size;
452 for (i = 1; i < initial_pagein; i++) {
453 if ((ma[i] = vm_page_lookup(object, i)) != NULL) {
454 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy)
455 break;
456 if (ma[i]->valid)
457 break;
458 vm_page_busy(ma[i]);
459 } else {
460 ma[i] = vm_page_alloc(object, i, VM_ALLOC_NORMAL);
461 if (ma[i] == NULL)
462 break;
463 }
464 }
465 initial_pagein = i;
466
467 rv = vm_pager_get_pages(object, ma, initial_pagein, 0);
468 ma[0] = vm_page_lookup(object, 0);
469
470 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || (ma[0]->valid == 0)) {
471 if (ma[0]) {
472 vm_page_protect(ma[0], VM_PROT_NONE);
473 vm_page_free(ma[0]);
474 }
475 splx(s);
476 return EIO;
477 }
478 }
479
480 vm_page_wire(ma[0]);
481 vm_page_wakeup(ma[0]);
482 splx(s);
483
484 pmap_kenter((vm_offset_t) imgp->image_header, VM_PAGE_TO_PHYS(ma[0]));
485 imgp->firstpage = ma[0];
486
487 return 0;
488}
489
490void
491exec_unmap_first_page(imgp)
492 struct image_params *imgp;
493{
494 if (imgp->firstpage) {
495 pmap_kremove((vm_offset_t) imgp->image_header);
496 vm_page_unwire(imgp->firstpage, 1);
497 imgp->firstpage = NULL;
498 }
499}
500
501/*
502 * Destroy old address space, and allocate a new stack
503 * The new stack is only SGROWSIZ large because it is grown
504 * automatically in trap.c.
505 */
506int
507exec_new_vmspace(imgp)
508 struct image_params *imgp;
509{
510 int error;
511 struct vmspace *vmspace = imgp->proc->p_vmspace;
512 vm_offset_t stack_addr = USRSTACK - maxssiz;
513 vm_map_t map = &vmspace->vm_map;
514
515 imgp->vmspace_destroyed = 1;
516
517 /*
518 * Prevent a pending AIO from modifying the new address space.
519 */
520 aio_proc_rundown(imgp->proc);
521
522 /*
523 * Blow away entire process VM, if address space not shared,
524 * otherwise, create a new VM space so that other threads are
525 * not disrupted
526 */
527 if (vmspace->vm_refcnt == 1) {
fef0fdf2 528 shmexit(vmspace);
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529 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS);
530 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS);
531 } else {
532 vmspace_exec(imgp->proc);
533 vmspace = imgp->proc->p_vmspace;
534 map = &vmspace->vm_map;
535 }
536
537 /* Allocate a new stack */
538 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz,
539 VM_PROT_ALL, VM_PROT_ALL, 0);
540 if (error)
541 return (error);
542
543 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the
544 * VM_STACK case, but they are still used to monitor the size of the
545 * process stack so we can check the stack rlimit.
546 */
547 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT;
548 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz;
549
550 return(0);
551}
552
553/*
554 * Copy out argument and environment strings from the old process
555 * address space into the temporary string buffer.
556 */
557int
558exec_extract_strings(imgp)
559 struct image_params *imgp;
560{
561 char **argv, **envv;
562 char *argp, *envp;
563 int error;
564 size_t length;
565
566 /*
567 * extract arguments first
568 */
569
570 argv = imgp->uap->argv;
571
572 if (argv) {
573 argp = (caddr_t) (intptr_t) fuword(argv);
574 if (argp == (caddr_t) -1)
575 return (EFAULT);
576 if (argp)
577 argv++;
578 if (imgp->argv0)
579 argp = imgp->argv0;
580 if (argp) {
581 do {
582 if (argp == (caddr_t) -1)
583 return (EFAULT);
584 if ((error = copyinstr(argp, imgp->stringp,
585 imgp->stringspace, &length))) {
586 if (error == ENAMETOOLONG)
587 return(E2BIG);
588 return (error);
589 }
590 imgp->stringspace -= length;
591 imgp->stringp += length;
592 imgp->argc++;
593 } while ((argp = (caddr_t) (intptr_t) fuword(argv++)));
594 }
595 }
596
597 imgp->endargs = imgp->stringp;
598
599 /*
600 * extract environment strings
601 */
602
603 envv = imgp->uap->envv;
604
605 if (envv) {
606 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) {
607 if (envp == (caddr_t) -1)
608 return (EFAULT);
609 if ((error = copyinstr(envp, imgp->stringp,
610 imgp->stringspace, &length))) {
611 if (error == ENAMETOOLONG)
612 return(E2BIG);
613 return (error);
614 }
615 imgp->stringspace -= length;
616 imgp->stringp += length;
617 imgp->envc++;
618 }
619 }
620
621 return (0);
622}
623
624/*
625 * Copy strings out to the new process address space, constructing
626 * new arg and env vector tables. Return a pointer to the base
627 * so that it can be used as the initial stack pointer.
628 */
629register_t *
630exec_copyout_strings(imgp)
631 struct image_params *imgp;
632{
633 int argc, envc;
634 char **vectp;
635 char *stringp, *destp;
636 register_t *stack_base;
637 struct ps_strings *arginfo;
638 int szsigcode;
639
640 /*
641 * Calculate string base and vector table pointers.
642 * Also deal with signal trampoline code for this exec type.
643 */
644 arginfo = (struct ps_strings *)PS_STRINGS;
645 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode);
646 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE -
647 roundup((ARG_MAX - imgp->stringspace), sizeof(char *));
648
649 /*
650 * install sigcode
651 */
652 if (szsigcode)
653 copyout(imgp->proc->p_sysent->sv_sigcode,
654 ((caddr_t)arginfo - szsigcode), szsigcode);
655
656 /*
657 * If we have a valid auxargs ptr, prepare some room
658 * on the stack.
659 */
660 if (imgp->auxargs)
661 /*
662 * The '+ 2' is for the null pointers at the end of each of the
663 * arg and env vector sets, and 'AT_COUNT*2' is room for the
664 * ELF Auxargs data.
665 */
666 vectp = (char **)(destp - (imgp->argc + imgp->envc + 2 +
667 AT_COUNT*2) * sizeof(char*));
668 else
669 /*
670 * The '+ 2' is for the null pointers at the end of each of the
671 * arg and env vector sets
672 */
673 vectp = (char **)
674 (destp - (imgp->argc + imgp->envc + 2) * sizeof(char*));
675
676 /*
677 * vectp also becomes our initial stack base
678 */
679 stack_base = (register_t *)vectp;
680
681 stringp = imgp->stringbase;
682 argc = imgp->argc;
683 envc = imgp->envc;
684
685 /*
686 * Copy out strings - arguments and environment.
687 */
688 copyout(stringp, destp, ARG_MAX - imgp->stringspace);
689
690 /*
691 * Fill in "ps_strings" struct for ps, w, etc.
692 */
693 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp);
694 suword(&arginfo->ps_nargvstr, argc);
695
696 /*
697 * Fill in argument portion of vector table.
698 */
699 for (; argc > 0; --argc) {
700 suword(vectp++, (long)(intptr_t)destp);
701 while (*stringp++ != 0)
702 destp++;
703 destp++;
704 }
705
706 /* a null vector table pointer seperates the argp's from the envp's */
707 suword(vectp++, 0);
708
709 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp);
710 suword(&arginfo->ps_nenvstr, envc);
711
712 /*
713 * Fill in environment portion of vector table.
714 */
715 for (; envc > 0; --envc) {
716 suword(vectp++, (long)(intptr_t)destp);
717 while (*stringp++ != 0)
718 destp++;
719 destp++;
720 }
721
722 /* end of vector table is a null pointer */
723 suword(vectp, 0);
724
725 return (stack_base);
726}
727
728/*
729 * Check permissions of file to execute.
730 * Return 0 for success or error code on failure.
731 */
732int
733exec_check_permissions(imgp)
734 struct image_params *imgp;
735{
736 struct proc *p = imgp->proc;
737 struct vnode *vp = imgp->vp;
738 struct vattr *attr = imgp->attr;
dadab5e9 739 struct thread *td = p->p_thread;
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740 int error;
741
742 /* Get file attributes */
3b568787 743 error = VOP_GETATTR(vp, attr, td);
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744 if (error)
745 return (error);
746
747 /*
748 * 1) Check if file execution is disabled for the filesystem that this
749 * file resides on.
750 * 2) Insure that at least one execute bit is on - otherwise root
751 * will always succeed, and we don't want to happen unless the
752 * file really is executable.
753 * 3) Insure that the file is a regular file.
754 */
755 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) ||
756 ((attr->va_mode & 0111) == 0) ||
757 (attr->va_type != VREG)) {
758 return (EACCES);
759 }
760
761 /*
762 * Zero length files can't be exec'd
763 */
764 if (attr->va_size == 0)
765 return (ENOEXEC);
766
767 /*
768 * Check for execute permission to file based on current credentials.
769 */
dadab5e9 770 error = VOP_ACCESS(vp, VEXEC, p->p_ucred, td);
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771 if (error)
772 return (error);
773
774 /*
775 * Check number of open-for-writes on the file and deny execution
776 * if there are any.
777 */
778 if (vp->v_writecount)
779 return (ETXTBSY);
780
781 /*
782 * Call filesystem specific open routine (which does nothing in the
783 * general case).
784 */
dadab5e9 785 error = VOP_OPEN(vp, FREAD, p->p_ucred, td);
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786 if (error)
787 return (error);
788
789 return (0);
790}
791
792/*
793 * Exec handler registration
794 */
795int
796exec_register(execsw_arg)
797 const struct execsw *execsw_arg;
798{
799 const struct execsw **es, **xs, **newexecsw;
800 int count = 2; /* New slot and trailing NULL */
801
802 if (execsw)
803 for (es = execsw; *es; es++)
804 count++;
805 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
806 if (newexecsw == NULL)
807 return ENOMEM;
808 xs = newexecsw;
809 if (execsw)
810 for (es = execsw; *es; es++)
811 *xs++ = *es;
812 *xs++ = execsw_arg;
813 *xs = NULL;
814 if (execsw)
815 free(execsw, M_TEMP);
816 execsw = newexecsw;
817 return 0;
818}
819
820int
821exec_unregister(execsw_arg)
822 const struct execsw *execsw_arg;
823{
824 const struct execsw **es, **xs, **newexecsw;
825 int count = 1;
826
827 if (execsw == NULL)
828 panic("unregister with no handlers left?\n");
829
830 for (es = execsw; *es; es++) {
831 if (*es == execsw_arg)
832 break;
833 }
834 if (*es == NULL)
835 return ENOENT;
836 for (es = execsw; *es; es++)
837 if (*es != execsw_arg)
838 count++;
839 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
840 if (newexecsw == NULL)
841 return ENOMEM;
842 xs = newexecsw;
843 for (es = execsw; *es; es++)
844 if (*es != execsw_arg)
845 *xs++ = *es;
846 *xs = NULL;
847 if (execsw)
848 free(execsw, M_TEMP);
849 execsw = newexecsw;
850 return 0;
851}