FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_exec.c
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
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD: releng/9.2/sys/kern/kern_exec.c 267018 2014-06-03 19:03:11Z delphij $");
29
30 #include "opt_capsicum.h"
31 #include "opt_hwpmc_hooks.h"
32 #include "opt_kdtrace.h"
33 #include "opt_ktrace.h"
34 #include "opt_vm.h"
35
36 #include <sys/param.h>
37 #include <sys/capability.h>
38 #include <sys/systm.h>
39 #include <sys/capability.h>
40 #include <sys/eventhandler.h>
41 #include <sys/lock.h>
42 #include <sys/mutex.h>
43 #include <sys/sysproto.h>
44 #include <sys/signalvar.h>
45 #include <sys/kernel.h>
46 #include <sys/mount.h>
47 #include <sys/filedesc.h>
48 #include <sys/fcntl.h>
49 #include <sys/acct.h>
50 #include <sys/exec.h>
51 #include <sys/imgact.h>
52 #include <sys/imgact_elf.h>
53 #include <sys/wait.h>
54 #include <sys/malloc.h>
55 #include <sys/priv.h>
56 #include <sys/proc.h>
57 #include <sys/pioctl.h>
58 #include <sys/namei.h>
59 #include <sys/resourcevar.h>
60 #include <sys/sched.h>
61 #include <sys/sdt.h>
62 #include <sys/sf_buf.h>
63 #include <sys/syscallsubr.h>
64 #include <sys/sysent.h>
65 #include <sys/shm.h>
66 #include <sys/sysctl.h>
67 #include <sys/vnode.h>
68 #include <sys/stat.h>
69 #ifdef KTRACE
70 #include <sys/ktrace.h>
71 #endif
72
73 #include <vm/vm.h>
74 #include <vm/vm_param.h>
75 #include <vm/pmap.h>
76 #include <vm/vm_page.h>
77 #include <vm/vm_map.h>
78 #include <vm/vm_kern.h>
79 #include <vm/vm_extern.h>
80 #include <vm/vm_object.h>
81 #include <vm/vm_pager.h>
82
83 #ifdef HWPMC_HOOKS
84 #include <sys/pmckern.h>
85 #endif
86
87 #include <machine/reg.h>
88
89 #include <security/audit/audit.h>
90 #include <security/mac/mac_framework.h>
91
92 #ifdef KDTRACE_HOOKS
93 #include <sys/dtrace_bsd.h>
94 dtrace_execexit_func_t dtrace_fasttrap_exec;
95 #endif
96
97 SDT_PROVIDER_DECLARE(proc);
98 SDT_PROBE_DEFINE(proc, kernel, , exec, exec);
99 SDT_PROBE_ARGTYPE(proc, kernel, , exec, 0, "char *");
100 SDT_PROBE_DEFINE(proc, kernel, , exec_failure, exec-failure);
101 SDT_PROBE_ARGTYPE(proc, kernel, , exec_failure, 0, "int");
102 SDT_PROBE_DEFINE(proc, kernel, , exec_success, exec-success);
103 SDT_PROBE_ARGTYPE(proc, kernel, , exec_success, 0, "char *");
104
105 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments");
106
107 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS);
108 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS);
109 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS);
110 static int do_execve(struct thread *td, struct image_args *args,
111 struct mac *mac_p);
112
113 /* XXX This should be vm_size_t. */
114 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD,
115 NULL, 0, sysctl_kern_ps_strings, "LU", "");
116
117 /* XXX This should be vm_size_t. */
118 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD|
119 CTLFLAG_CAPRD, NULL, 0, sysctl_kern_usrstack, "LU", "");
120
121 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD,
122 NULL, 0, sysctl_kern_stackprot, "I", "");
123
124 u_long ps_arg_cache_limit = PAGE_SIZE / 16;
125 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW,
126 &ps_arg_cache_limit, 0, "");
127
128 static int map_at_zero = 0;
129 TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero);
130 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &map_at_zero, 0,
131 "Permit processes to map an object at virtual address 0.");
132
133 static int
134 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)
135 {
136 struct proc *p;
137 int error;
138
139 p = curproc;
140 #ifdef SCTL_MASK32
141 if (req->flags & SCTL_MASK32) {
142 unsigned int val;
143 val = (unsigned int)p->p_sysent->sv_psstrings;
144 error = SYSCTL_OUT(req, &val, sizeof(val));
145 } else
146 #endif
147 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings,
148 sizeof(p->p_sysent->sv_psstrings));
149 return error;
150 }
151
152 static int
153 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)
154 {
155 struct proc *p;
156 int error;
157
158 p = curproc;
159 #ifdef SCTL_MASK32
160 if (req->flags & SCTL_MASK32) {
161 unsigned int val;
162 val = (unsigned int)p->p_sysent->sv_usrstack;
163 error = SYSCTL_OUT(req, &val, sizeof(val));
164 } else
165 #endif
166 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack,
167 sizeof(p->p_sysent->sv_usrstack));
168 return error;
169 }
170
171 static int
172 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS)
173 {
174 struct proc *p;
175
176 p = curproc;
177 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot,
178 sizeof(p->p_sysent->sv_stackprot)));
179 }
180
181 /*
182 * Each of the items is a pointer to a `const struct execsw', hence the
183 * double pointer here.
184 */
185 static const struct execsw **execsw;
186
187 #ifndef _SYS_SYSPROTO_H_
188 struct execve_args {
189 char *fname;
190 char **argv;
191 char **envv;
192 };
193 #endif
194
195 int
196 sys_execve(td, uap)
197 struct thread *td;
198 struct execve_args /* {
199 char *fname;
200 char **argv;
201 char **envv;
202 } */ *uap;
203 {
204 int error;
205 struct image_args args;
206
207 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
208 uap->argv, uap->envv);
209 if (error == 0)
210 error = kern_execve(td, &args, NULL);
211 return (error);
212 }
213
214 #ifndef _SYS_SYSPROTO_H_
215 struct fexecve_args {
216 int fd;
217 char **argv;
218 char **envv;
219 }
220 #endif
221 int
222 sys_fexecve(struct thread *td, struct fexecve_args *uap)
223 {
224 int error;
225 struct image_args args;
226
227 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE,
228 uap->argv, uap->envv);
229 if (error == 0) {
230 args.fd = uap->fd;
231 error = kern_execve(td, &args, NULL);
232 }
233 return (error);
234 }
235
236 #ifndef _SYS_SYSPROTO_H_
237 struct __mac_execve_args {
238 char *fname;
239 char **argv;
240 char **envv;
241 struct mac *mac_p;
242 };
243 #endif
244
245 int
246 sys___mac_execve(td, uap)
247 struct thread *td;
248 struct __mac_execve_args /* {
249 char *fname;
250 char **argv;
251 char **envv;
252 struct mac *mac_p;
253 } */ *uap;
254 {
255 #ifdef MAC
256 int error;
257 struct image_args args;
258
259 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
260 uap->argv, uap->envv);
261 if (error == 0)
262 error = kern_execve(td, &args, uap->mac_p);
263 return (error);
264 #else
265 return (ENOSYS);
266 #endif
267 }
268
269 /*
270 * XXX: kern_execve has the astonishing property of not always returning to
271 * the caller. If sufficiently bad things happen during the call to
272 * do_execve(), it can end up calling exit1(); as a result, callers must
273 * avoid doing anything which they might need to undo (e.g., allocating
274 * memory).
275 */
276 int
277 kern_execve(td, args, mac_p)
278 struct thread *td;
279 struct image_args *args;
280 struct mac *mac_p;
281 {
282 struct proc *p = td->td_proc;
283 struct vmspace *oldvmspace;
284 int error;
285
286 AUDIT_ARG_ARGV(args->begin_argv, args->argc,
287 args->begin_envv - args->begin_argv);
288 AUDIT_ARG_ENVV(args->begin_envv, args->envc,
289 args->endp - args->begin_envv);
290 if (p->p_flag & P_HADTHREADS) {
291 PROC_LOCK(p);
292 if (thread_single(SINGLE_BOUNDARY)) {
293 PROC_UNLOCK(p);
294 exec_free_args(args);
295 return (ERESTART); /* Try again later. */
296 }
297 PROC_UNLOCK(p);
298 }
299
300 KASSERT((td->td_pflags & TDP_EXECVMSPC) == 0, ("nested execve"));
301 oldvmspace = td->td_proc->p_vmspace;
302 error = do_execve(td, args, mac_p);
303
304 if (p->p_flag & P_HADTHREADS) {
305 PROC_LOCK(p);
306 /*
307 * If success, we upgrade to SINGLE_EXIT state to
308 * force other threads to suicide.
309 */
310 if (error == 0)
311 thread_single(SINGLE_EXIT);
312 else
313 thread_single_end();
314 PROC_UNLOCK(p);
315 }
316 if ((td->td_pflags & TDP_EXECVMSPC) != 0) {
317 KASSERT(td->td_proc->p_vmspace != oldvmspace,
318 ("oldvmspace still used"));
319 vmspace_free(oldvmspace);
320 td->td_pflags &= ~TDP_EXECVMSPC;
321 }
322
323 return (error);
324 }
325
326 /*
327 * In-kernel implementation of execve(). All arguments are assumed to be
328 * userspace pointers from the passed thread.
329 */
330 static int
331 do_execve(td, args, mac_p)
332 struct thread *td;
333 struct image_args *args;
334 struct mac *mac_p;
335 {
336 struct proc *p = td->td_proc;
337 struct nameidata nd;
338 struct ucred *newcred = NULL, *oldcred;
339 struct uidinfo *euip;
340 register_t *stack_base;
341 int error, i;
342 struct image_params image_params, *imgp;
343 struct vattr attr;
344 int (*img_first)(struct image_params *);
345 struct pargs *oldargs = NULL, *newargs = NULL;
346 struct sigacts *oldsigacts, *newsigacts;
347 #ifdef KTRACE
348 struct vnode *tracevp = NULL;
349 struct ucred *tracecred = NULL;
350 #endif
351 struct vnode *textvp = NULL, *binvp = NULL;
352 int credential_changing;
353 int vfslocked;
354 int textset;
355 #ifdef MAC
356 struct label *interpvplabel = NULL;
357 int will_transition;
358 #endif
359 #ifdef HWPMC_HOOKS
360 struct pmckern_procexec pe;
361 #endif
362 static const char fexecv_proc_title[] = "(fexecv)";
363
364 vfslocked = 0;
365 imgp = &image_params;
366
367 /*
368 * Lock the process and set the P_INEXEC flag to indicate that
369 * it should be left alone until we're done here. This is
370 * necessary to avoid race conditions - e.g. in ptrace() -
371 * that might allow a local user to illicitly obtain elevated
372 * privileges.
373 */
374 PROC_LOCK(p);
375 KASSERT((p->p_flag & P_INEXEC) == 0,
376 ("%s(): process already has P_INEXEC flag", __func__));
377 p->p_flag |= P_INEXEC;
378 PROC_UNLOCK(p);
379
380 /*
381 * Initialize part of the common data
382 */
383 imgp->proc = p;
384 imgp->execlabel = NULL;
385 imgp->attr = &attr;
386 imgp->entry_addr = 0;
387 imgp->reloc_base = 0;
388 imgp->vmspace_destroyed = 0;
389 imgp->interpreted = 0;
390 imgp->opened = 0;
391 imgp->interpreter_name = NULL;
392 imgp->auxargs = NULL;
393 imgp->vp = NULL;
394 imgp->object = NULL;
395 imgp->firstpage = NULL;
396 imgp->ps_strings = 0;
397 imgp->auxarg_size = 0;
398 imgp->args = args;
399 imgp->execpath = imgp->freepath = NULL;
400 imgp->execpathp = 0;
401 imgp->canary = 0;
402 imgp->canarylen = 0;
403 imgp->pagesizes = 0;
404 imgp->pagesizeslen = 0;
405 imgp->stack_prot = 0;
406
407 #ifdef MAC
408 error = mac_execve_enter(imgp, mac_p);
409 if (error)
410 goto exec_fail;
411 #endif
412
413 imgp->image_header = NULL;
414
415 /*
416 * Translate the file name. namei() returns a vnode pointer
417 * in ni_vp amoung other things.
418 *
419 * XXXAUDIT: It would be desirable to also audit the name of the
420 * interpreter if this is an interpreted binary.
421 */
422 if (args->fname != NULL) {
423 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME
424 | MPSAFE | AUDITVNODE1, UIO_SYSSPACE, args->fname, td);
425 }
426
427 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 );
428
429 interpret:
430 if (args->fname != NULL) {
431 #ifdef CAPABILITY_MODE
432 /*
433 * While capability mode can't reach this point via direct
434 * path arguments to execve(), we also don't allow
435 * interpreters to be used in capability mode (for now).
436 * Catch indirect lookups and return a permissions error.
437 */
438 if (IN_CAPABILITY_MODE(td)) {
439 error = ECAPMODE;
440 goto exec_fail;
441 }
442 #endif
443 error = namei(&nd);
444 if (error)
445 goto exec_fail;
446
447 vfslocked = NDHASGIANT(&nd);
448 binvp = nd.ni_vp;
449 imgp->vp = binvp;
450 } else {
451 AUDIT_ARG_FD(args->fd);
452 /*
453 * Some might argue that CAP_READ and/or CAP_MMAP should also
454 * be required here; such arguments will be entertained.
455 *
456 * Descriptors opened only with O_EXEC or O_RDONLY are allowed.
457 */
458 error = fgetvp_exec(td, args->fd, CAP_FEXECVE, &binvp);
459 if (error)
460 goto exec_fail;
461 vfslocked = VFS_LOCK_GIANT(binvp->v_mount);
462 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY);
463 AUDIT_ARG_VNODE1(binvp);
464 imgp->vp = binvp;
465 }
466
467 /*
468 * Check file permissions (also 'opens' file)
469 */
470 error = exec_check_permissions(imgp);
471 if (error)
472 goto exec_fail_dealloc;
473
474 imgp->object = imgp->vp->v_object;
475 if (imgp->object != NULL)
476 vm_object_reference(imgp->object);
477
478 /*
479 * Set VV_TEXT now so no one can write to the executable while we're
480 * activating it.
481 *
482 * Remember if this was set before and unset it in case this is not
483 * actually an executable image.
484 */
485 textset = VOP_IS_TEXT(imgp->vp);
486 VOP_SET_TEXT(imgp->vp);
487
488 error = exec_map_first_page(imgp);
489 if (error)
490 goto exec_fail_dealloc;
491
492 imgp->proc->p_osrel = 0;
493 /*
494 * If the current process has a special image activator it
495 * wants to try first, call it. For example, emulating shell
496 * scripts differently.
497 */
498 error = -1;
499 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL)
500 error = img_first(imgp);
501
502 /*
503 * Loop through the list of image activators, calling each one.
504 * An activator returns -1 if there is no match, 0 on success,
505 * and an error otherwise.
506 */
507 for (i = 0; error == -1 && execsw[i]; ++i) {
508 if (execsw[i]->ex_imgact == NULL ||
509 execsw[i]->ex_imgact == img_first) {
510 continue;
511 }
512 error = (*execsw[i]->ex_imgact)(imgp);
513 }
514
515 if (error) {
516 if (error == -1) {
517 if (textset == 0)
518 VOP_UNSET_TEXT(imgp->vp);
519 error = ENOEXEC;
520 }
521 goto exec_fail_dealloc;
522 }
523
524 /*
525 * Special interpreter operation, cleanup and loop up to try to
526 * activate the interpreter.
527 */
528 if (imgp->interpreted) {
529 exec_unmap_first_page(imgp);
530 /*
531 * VV_TEXT needs to be unset for scripts. There is a short
532 * period before we determine that something is a script where
533 * VV_TEXT will be set. The vnode lock is held over this
534 * entire period so nothing should illegitimately be blocked.
535 */
536 VOP_UNSET_TEXT(imgp->vp);
537 /* free name buffer and old vnode */
538 if (args->fname != NULL)
539 NDFREE(&nd, NDF_ONLY_PNBUF);
540 #ifdef MAC
541 mac_execve_interpreter_enter(binvp, &interpvplabel);
542 #endif
543 if (imgp->opened) {
544 VOP_CLOSE(binvp, FREAD, td->td_ucred, td);
545 imgp->opened = 0;
546 }
547 vput(binvp);
548 vm_object_deallocate(imgp->object);
549 imgp->object = NULL;
550 VFS_UNLOCK_GIANT(vfslocked);
551 vfslocked = 0;
552 /* set new name to that of the interpreter */
553 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME | MPSAFE,
554 UIO_SYSSPACE, imgp->interpreter_name, td);
555 args->fname = imgp->interpreter_name;
556 goto interpret;
557 }
558
559 /*
560 * NB: We unlock the vnode here because it is believed that none
561 * of the sv_copyout_strings/sv_fixup operations require the vnode.
562 */
563 VOP_UNLOCK(imgp->vp, 0);
564
565 /*
566 * Do the best to calculate the full path to the image file.
567 */
568 if (imgp->auxargs != NULL &&
569 ((args->fname != NULL && args->fname[0] == '/') ||
570 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0))
571 imgp->execpath = args->fname;
572
573 /*
574 * Copy out strings (args and env) and initialize stack base
575 */
576 if (p->p_sysent->sv_copyout_strings)
577 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp);
578 else
579 stack_base = exec_copyout_strings(imgp);
580
581 /*
582 * If custom stack fixup routine present for this process
583 * let it do the stack setup.
584 * Else stuff argument count as first item on stack
585 */
586 if (p->p_sysent->sv_fixup != NULL)
587 (*p->p_sysent->sv_fixup)(&stack_base, imgp);
588 else
589 suword(--stack_base, imgp->args->argc);
590
591 /*
592 * For security and other reasons, the file descriptor table cannot
593 * be shared after an exec.
594 */
595 fdunshare(p, td);
596
597 /*
598 * Malloc things before we need locks.
599 */
600 newcred = crget();
601 euip = uifind(attr.va_uid);
602 i = imgp->args->begin_envv - imgp->args->begin_argv;
603 /* Cache arguments if they fit inside our allowance */
604 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) {
605 newargs = pargs_alloc(i);
606 bcopy(imgp->args->begin_argv, newargs->ar_args, i);
607 }
608
609 /* close files on exec */
610 fdcloseexec(td);
611 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
612
613 /* Get a reference to the vnode prior to locking the proc */
614 VREF(binvp);
615
616 /*
617 * For security and other reasons, signal handlers cannot
618 * be shared after an exec. The new process gets a copy of the old
619 * handlers. In execsigs(), the new process will have its signals
620 * reset.
621 */
622 PROC_LOCK(p);
623 oldcred = crcopysafe(p, newcred);
624 if (sigacts_shared(p->p_sigacts)) {
625 oldsigacts = p->p_sigacts;
626 PROC_UNLOCK(p);
627 newsigacts = sigacts_alloc();
628 sigacts_copy(newsigacts, oldsigacts);
629 PROC_LOCK(p);
630 p->p_sigacts = newsigacts;
631 } else
632 oldsigacts = NULL;
633
634 /* Stop profiling */
635 stopprofclock(p);
636
637 /* reset caught signals */
638 execsigs(p);
639
640 /* name this process - nameiexec(p, ndp) */
641 bzero(p->p_comm, sizeof(p->p_comm));
642 if (args->fname)
643 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm,
644 min(nd.ni_cnd.cn_namelen, MAXCOMLEN));
645 else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0)
646 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title));
647 bcopy(p->p_comm, td->td_name, sizeof(td->td_name));
648 #ifdef KTR
649 sched_clear_tdname(td);
650 #endif
651
652 /*
653 * mark as execed, wakeup the process that vforked (if any) and tell
654 * it that it now has its own resources back
655 */
656 p->p_flag |= P_EXEC;
657 if (p->p_pptr && (p->p_flag & P_PPWAIT)) {
658 p->p_flag &= ~(P_PPWAIT | P_PPTRACE);
659 cv_broadcast(&p->p_pwait);
660 }
661
662 /*
663 * Implement image setuid/setgid.
664 *
665 * Don't honor setuid/setgid if the filesystem prohibits it or if
666 * the process is being traced.
667 *
668 * We disable setuid/setgid/etc in compatibility mode on the basis
669 * that most setugid applications are not written with that
670 * environment in mind, and will therefore almost certainly operate
671 * incorrectly. In principle there's no reason that setugid
672 * applications might not be useful in capability mode, so we may want
673 * to reconsider this conservative design choice in the future.
674 *
675 * XXXMAC: For the time being, use NOSUID to also prohibit
676 * transitions on the file system.
677 */
678 credential_changing = 0;
679 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid !=
680 attr.va_uid;
681 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid !=
682 attr.va_gid;
683 #ifdef MAC
684 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp,
685 interpvplabel, imgp);
686 credential_changing |= will_transition;
687 #endif
688
689 if (credential_changing &&
690 #ifdef CAPABILITY_MODE
691 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) &&
692 #endif
693 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 &&
694 (p->p_flag & P_TRACED) == 0) {
695 /*
696 * Turn off syscall tracing for set-id programs, except for
697 * root. Record any set-id flags first to make sure that
698 * we do not regain any tracing during a possible block.
699 */
700 setsugid(p);
701
702 #ifdef KTRACE
703 if (p->p_tracecred != NULL &&
704 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0))
705 ktrprocexec(p, &tracecred, &tracevp);
706 #endif
707 /*
708 * Close any file descriptors 0..2 that reference procfs,
709 * then make sure file descriptors 0..2 are in use.
710 *
711 * setugidsafety() may call closef() and then pfind()
712 * which may grab the process lock.
713 * fdcheckstd() may call falloc() which may block to
714 * allocate memory, so temporarily drop the process lock.
715 */
716 PROC_UNLOCK(p);
717 VOP_UNLOCK(imgp->vp, 0);
718 setugidsafety(td);
719 error = fdcheckstd(td);
720 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
721 if (error != 0)
722 goto done1;
723 PROC_LOCK(p);
724 /*
725 * Set the new credentials.
726 */
727 if (attr.va_mode & S_ISUID)
728 change_euid(newcred, euip);
729 if (attr.va_mode & S_ISGID)
730 change_egid(newcred, attr.va_gid);
731 #ifdef MAC
732 if (will_transition) {
733 mac_vnode_execve_transition(oldcred, newcred, imgp->vp,
734 interpvplabel, imgp);
735 }
736 #endif
737 /*
738 * Implement correct POSIX saved-id behavior.
739 *
740 * XXXMAC: Note that the current logic will save the
741 * uid and gid if a MAC domain transition occurs, even
742 * though maybe it shouldn't.
743 */
744 change_svuid(newcred, newcred->cr_uid);
745 change_svgid(newcred, newcred->cr_gid);
746 p->p_ucred = newcred;
747 newcred = NULL;
748 } else {
749 if (oldcred->cr_uid == oldcred->cr_ruid &&
750 oldcred->cr_gid == oldcred->cr_rgid)
751 p->p_flag &= ~P_SUGID;
752 /*
753 * Implement correct POSIX saved-id behavior.
754 *
755 * XXX: It's not clear that the existing behavior is
756 * POSIX-compliant. A number of sources indicate that the
757 * saved uid/gid should only be updated if the new ruid is
758 * not equal to the old ruid, or the new euid is not equal
759 * to the old euid and the new euid is not equal to the old
760 * ruid. The FreeBSD code always updates the saved uid/gid.
761 * Also, this code uses the new (replaced) euid and egid as
762 * the source, which may or may not be the right ones to use.
763 */
764 if (oldcred->cr_svuid != oldcred->cr_uid ||
765 oldcred->cr_svgid != oldcred->cr_gid) {
766 change_svuid(newcred, newcred->cr_uid);
767 change_svgid(newcred, newcred->cr_gid);
768 p->p_ucred = newcred;
769 newcred = NULL;
770 }
771 }
772
773 /*
774 * Store the vp for use in procfs. This vnode was referenced prior
775 * to locking the proc lock.
776 */
777 textvp = p->p_textvp;
778 p->p_textvp = binvp;
779
780 #ifdef KDTRACE_HOOKS
781 /*
782 * Tell the DTrace fasttrap provider about the exec if it
783 * has declared an interest.
784 */
785 if (dtrace_fasttrap_exec)
786 dtrace_fasttrap_exec(p);
787 #endif
788
789 /*
790 * Notify others that we exec'd, and clear the P_INEXEC flag
791 * as we're now a bona fide freshly-execed process.
792 */
793 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC);
794 p->p_flag &= ~P_INEXEC;
795
796 /* clear "fork but no exec" flag, as we _are_ execing */
797 p->p_acflag &= ~AFORK;
798
799 /*
800 * Free any previous argument cache and replace it with
801 * the new argument cache, if any.
802 */
803 oldargs = p->p_args;
804 p->p_args = newargs;
805 newargs = NULL;
806
807 #ifdef HWPMC_HOOKS
808 /*
809 * Check if system-wide sampling is in effect or if the
810 * current process is using PMCs. If so, do exec() time
811 * processing. This processing needs to happen AFTER the
812 * P_INEXEC flag is cleared.
813 *
814 * The proc lock needs to be released before taking the PMC
815 * SX.
816 */
817 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) {
818 PROC_UNLOCK(p);
819 VOP_UNLOCK(imgp->vp, 0);
820 pe.pm_credentialschanged = credential_changing;
821 pe.pm_entryaddr = imgp->entry_addr;
822
823 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe);
824 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
825 } else
826 PROC_UNLOCK(p);
827 #else /* !HWPMC_HOOKS */
828 PROC_UNLOCK(p);
829 #endif
830
831 /* Set values passed into the program in registers. */
832 if (p->p_sysent->sv_setregs)
833 (*p->p_sysent->sv_setregs)(td, imgp,
834 (u_long)(uintptr_t)stack_base);
835 else
836 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base);
837
838 vfs_mark_atime(imgp->vp, td->td_ucred);
839
840 SDT_PROBE(proc, kernel, , exec_success, args->fname, 0, 0, 0, 0);
841
842 done1:
843 /*
844 * Free any resources malloc'd earlier that we didn't use.
845 */
846 uifree(euip);
847 if (newcred == NULL)
848 crfree(oldcred);
849 else
850 crfree(newcred);
851 VOP_UNLOCK(imgp->vp, 0);
852
853 /*
854 * Handle deferred decrement of ref counts.
855 */
856 if (textvp != NULL) {
857 int tvfslocked;
858
859 tvfslocked = VFS_LOCK_GIANT(textvp->v_mount);
860 vrele(textvp);
861 VFS_UNLOCK_GIANT(tvfslocked);
862 }
863 if (binvp && error != 0)
864 vrele(binvp);
865 #ifdef KTRACE
866 if (tracevp != NULL) {
867 int tvfslocked;
868
869 tvfslocked = VFS_LOCK_GIANT(tracevp->v_mount);
870 vrele(tracevp);
871 VFS_UNLOCK_GIANT(tvfslocked);
872 }
873 if (tracecred != NULL)
874 crfree(tracecred);
875 #endif
876 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
877 pargs_drop(oldargs);
878 pargs_drop(newargs);
879 if (oldsigacts != NULL)
880 sigacts_free(oldsigacts);
881
882 exec_fail_dealloc:
883
884 /*
885 * free various allocated resources
886 */
887 if (imgp->firstpage != NULL)
888 exec_unmap_first_page(imgp);
889
890 if (imgp->vp != NULL) {
891 if (args->fname)
892 NDFREE(&nd, NDF_ONLY_PNBUF);
893 if (imgp->opened)
894 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td);
895 vput(imgp->vp);
896 }
897
898 if (imgp->object != NULL)
899 vm_object_deallocate(imgp->object);
900
901 free(imgp->freepath, M_TEMP);
902
903 if (error == 0) {
904 PROC_LOCK(p);
905 td->td_dbgflags |= TDB_EXEC;
906 PROC_UNLOCK(p);
907
908 /*
909 * Stop the process here if its stop event mask has
910 * the S_EXEC bit set.
911 */
912 STOPEVENT(p, S_EXEC, 0);
913 goto done2;
914 }
915
916 exec_fail:
917 /* we're done here, clear P_INEXEC */
918 PROC_LOCK(p);
919 p->p_flag &= ~P_INEXEC;
920 PROC_UNLOCK(p);
921
922 SDT_PROBE(proc, kernel, , exec_failure, error, 0, 0, 0, 0);
923
924 done2:
925 #ifdef MAC
926 mac_execve_exit(imgp);
927 mac_execve_interpreter_exit(interpvplabel);
928 #endif
929 VFS_UNLOCK_GIANT(vfslocked);
930 exec_free_args(args);
931
932 if (error && imgp->vmspace_destroyed) {
933 /* sorry, no more process anymore. exit gracefully */
934 exit1(td, W_EXITCODE(0, SIGABRT));
935 /* NOT REACHED */
936 }
937
938 #ifdef KTRACE
939 if (error == 0)
940 ktrprocctor(p);
941 #endif
942
943 return (error);
944 }
945
946 int
947 exec_map_first_page(imgp)
948 struct image_params *imgp;
949 {
950 int rv, i;
951 int initial_pagein;
952 vm_page_t ma[VM_INITIAL_PAGEIN];
953 vm_object_t object;
954
955 if (imgp->firstpage != NULL)
956 exec_unmap_first_page(imgp);
957
958 object = imgp->vp->v_object;
959 if (object == NULL)
960 return (EACCES);
961 VM_OBJECT_LOCK(object);
962 #if VM_NRESERVLEVEL > 0
963 if ((object->flags & OBJ_COLORED) == 0) {
964 object->flags |= OBJ_COLORED;
965 object->pg_color = 0;
966 }
967 #endif
968 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
969 if (ma[0]->valid != VM_PAGE_BITS_ALL) {
970 initial_pagein = VM_INITIAL_PAGEIN;
971 if (initial_pagein > object->size)
972 initial_pagein = object->size;
973 for (i = 1; i < initial_pagein; i++) {
974 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) {
975 if (ma[i]->valid)
976 break;
977 if ((ma[i]->oflags & VPO_BUSY) || ma[i]->busy)
978 break;
979 vm_page_busy(ma[i]);
980 } else {
981 ma[i] = vm_page_alloc(object, i,
982 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED);
983 if (ma[i] == NULL)
984 break;
985 }
986 }
987 initial_pagein = i;
988 rv = vm_pager_get_pages(object, ma, initial_pagein, 0);
989 ma[0] = vm_page_lookup(object, 0);
990 if ((rv != VM_PAGER_OK) || (ma[0] == NULL)) {
991 if (ma[0] != NULL) {
992 vm_page_lock(ma[0]);
993 vm_page_free(ma[0]);
994 vm_page_unlock(ma[0]);
995 }
996 VM_OBJECT_UNLOCK(object);
997 return (EIO);
998 }
999 }
1000 vm_page_lock(ma[0]);
1001 vm_page_hold(ma[0]);
1002 vm_page_unlock(ma[0]);
1003 vm_page_wakeup(ma[0]);
1004 VM_OBJECT_UNLOCK(object);
1005
1006 imgp->firstpage = sf_buf_alloc(ma[0], 0);
1007 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage);
1008
1009 return (0);
1010 }
1011
1012 void
1013 exec_unmap_first_page(imgp)
1014 struct image_params *imgp;
1015 {
1016 vm_page_t m;
1017
1018 if (imgp->firstpage != NULL) {
1019 m = sf_buf_page(imgp->firstpage);
1020 sf_buf_free(imgp->firstpage);
1021 imgp->firstpage = NULL;
1022 vm_page_lock(m);
1023 vm_page_unhold(m);
1024 vm_page_unlock(m);
1025 }
1026 }
1027
1028 /*
1029 * Destroy old address space, and allocate a new stack
1030 * The new stack is only SGROWSIZ large because it is grown
1031 * automatically in trap.c.
1032 */
1033 int
1034 exec_new_vmspace(imgp, sv)
1035 struct image_params *imgp;
1036 struct sysentvec *sv;
1037 {
1038 int error;
1039 struct proc *p = imgp->proc;
1040 struct vmspace *vmspace = p->p_vmspace;
1041 vm_object_t obj;
1042 vm_offset_t sv_minuser, stack_addr;
1043 vm_map_t map;
1044 u_long ssiz;
1045
1046 imgp->vmspace_destroyed = 1;
1047 imgp->sysent = sv;
1048
1049 /* May be called with Giant held */
1050 EVENTHANDLER_INVOKE(process_exec, p, imgp);
1051
1052 /*
1053 * Blow away entire process VM, if address space not shared,
1054 * otherwise, create a new VM space so that other threads are
1055 * not disrupted
1056 */
1057 map = &vmspace->vm_map;
1058 if (map_at_zero)
1059 sv_minuser = sv->sv_minuser;
1060 else
1061 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE);
1062 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser &&
1063 vm_map_max(map) == sv->sv_maxuser) {
1064 shmexit(vmspace);
1065 pmap_remove_pages(vmspace_pmap(vmspace));
1066 vm_map_remove(map, vm_map_min(map), vm_map_max(map));
1067 } else {
1068 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser);
1069 if (error)
1070 return (error);
1071 vmspace = p->p_vmspace;
1072 map = &vmspace->vm_map;
1073 }
1074
1075 /* Map a shared page */
1076 obj = sv->sv_shared_page_obj;
1077 if (obj != NULL) {
1078 vm_object_reference(obj);
1079 error = vm_map_fixed(map, obj, 0,
1080 sv->sv_shared_page_base, sv->sv_shared_page_len,
1081 VM_PROT_READ | VM_PROT_EXECUTE,
1082 VM_PROT_READ | VM_PROT_EXECUTE,
1083 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE);
1084 if (error) {
1085 vm_object_deallocate(obj);
1086 return (error);
1087 }
1088 }
1089
1090 /* Allocate a new stack */
1091 if (sv->sv_maxssiz != NULL)
1092 ssiz = *sv->sv_maxssiz;
1093 else
1094 ssiz = maxssiz;
1095 stack_addr = sv->sv_usrstack - ssiz;
1096 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz,
1097 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot :
1098 sv->sv_stackprot,
1099 VM_PROT_ALL, MAP_STACK_GROWS_DOWN);
1100 if (error)
1101 return (error);
1102
1103 #ifdef __ia64__
1104 /* Allocate a new register stack */
1105 stack_addr = IA64_BACKINGSTORE;
1106 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz,
1107 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP);
1108 if (error)
1109 return (error);
1110 #endif
1111
1112 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the
1113 * VM_STACK case, but they are still used to monitor the size of the
1114 * process stack so we can check the stack rlimit.
1115 */
1116 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT;
1117 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz;
1118
1119 return (0);
1120 }
1121
1122 /*
1123 * Copy out argument and environment strings from the old process address
1124 * space into the temporary string buffer.
1125 */
1126 int
1127 exec_copyin_args(struct image_args *args, char *fname,
1128 enum uio_seg segflg, char **argv, char **envv)
1129 {
1130 char *argp, *envp;
1131 int error;
1132 size_t length;
1133
1134 bzero(args, sizeof(*args));
1135 if (argv == NULL)
1136 return (EFAULT);
1137
1138 /*
1139 * Allocate demand-paged memory for the file name, argument, and
1140 * environment strings.
1141 */
1142 error = exec_alloc_args(args);
1143 if (error != 0)
1144 return (error);
1145
1146 /*
1147 * Copy the file name.
1148 */
1149 if (fname != NULL) {
1150 args->fname = args->buf;
1151 error = (segflg == UIO_SYSSPACE) ?
1152 copystr(fname, args->fname, PATH_MAX, &length) :
1153 copyinstr(fname, args->fname, PATH_MAX, &length);
1154 if (error != 0)
1155 goto err_exit;
1156 } else
1157 length = 0;
1158
1159 args->begin_argv = args->buf + length;
1160 args->endp = args->begin_argv;
1161 args->stringspace = ARG_MAX;
1162
1163 /*
1164 * extract arguments first
1165 */
1166 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) {
1167 if (argp == (caddr_t) -1) {
1168 error = EFAULT;
1169 goto err_exit;
1170 }
1171 if ((error = copyinstr(argp, args->endp,
1172 args->stringspace, &length))) {
1173 if (error == ENAMETOOLONG)
1174 error = E2BIG;
1175 goto err_exit;
1176 }
1177 args->stringspace -= length;
1178 args->endp += length;
1179 args->argc++;
1180 }
1181
1182 args->begin_envv = args->endp;
1183
1184 /*
1185 * extract environment strings
1186 */
1187 if (envv) {
1188 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) {
1189 if (envp == (caddr_t)-1) {
1190 error = EFAULT;
1191 goto err_exit;
1192 }
1193 if ((error = copyinstr(envp, args->endp,
1194 args->stringspace, &length))) {
1195 if (error == ENAMETOOLONG)
1196 error = E2BIG;
1197 goto err_exit;
1198 }
1199 args->stringspace -= length;
1200 args->endp += length;
1201 args->envc++;
1202 }
1203 }
1204
1205 return (0);
1206
1207 err_exit:
1208 exec_free_args(args);
1209 return (error);
1210 }
1211
1212 /*
1213 * Allocate temporary demand-paged, zero-filled memory for the file name,
1214 * argument, and environment strings. Returns zero if the allocation succeeds
1215 * and ENOMEM otherwise.
1216 */
1217 int
1218 exec_alloc_args(struct image_args *args)
1219 {
1220
1221 args->buf = (char *)kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX);
1222 return (args->buf != NULL ? 0 : ENOMEM);
1223 }
1224
1225 void
1226 exec_free_args(struct image_args *args)
1227 {
1228
1229 if (args->buf != NULL) {
1230 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf,
1231 PATH_MAX + ARG_MAX);
1232 args->buf = NULL;
1233 }
1234 if (args->fname_buf != NULL) {
1235 free(args->fname_buf, M_TEMP);
1236 args->fname_buf = NULL;
1237 }
1238 }
1239
1240 /*
1241 * Copy strings out to the new process address space, constructing new arg
1242 * and env vector tables. Return a pointer to the base so that it can be used
1243 * as the initial stack pointer.
1244 */
1245 register_t *
1246 exec_copyout_strings(imgp)
1247 struct image_params *imgp;
1248 {
1249 int argc, envc;
1250 char **vectp;
1251 char *stringp, *destp;
1252 register_t *stack_base;
1253 struct ps_strings *arginfo;
1254 struct proc *p;
1255 size_t execpath_len;
1256 int szsigcode, szps;
1257 char canary[sizeof(long) * 8];
1258
1259 szps = sizeof(pagesizes[0]) * MAXPAGESIZES;
1260 /*
1261 * Calculate string base and vector table pointers.
1262 * Also deal with signal trampoline code for this exec type.
1263 */
1264 if (imgp->execpath != NULL && imgp->auxargs != NULL)
1265 execpath_len = strlen(imgp->execpath) + 1;
1266 else
1267 execpath_len = 0;
1268 p = imgp->proc;
1269 szsigcode = 0;
1270 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings;
1271 if (p->p_sysent->sv_sigcode_base == 0) {
1272 if (p->p_sysent->sv_szsigcode != NULL)
1273 szsigcode = *(p->p_sysent->sv_szsigcode);
1274 }
1275 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE -
1276 roundup(execpath_len, sizeof(char *)) -
1277 roundup(sizeof(canary), sizeof(char *)) -
1278 roundup(szps, sizeof(char *)) -
1279 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *));
1280
1281 /*
1282 * install sigcode
1283 */
1284 if (szsigcode != 0)
1285 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo -
1286 szsigcode), szsigcode);
1287
1288 /*
1289 * Copy the image path for the rtld.
1290 */
1291 if (execpath_len != 0) {
1292 imgp->execpathp = (uintptr_t)arginfo - szsigcode - execpath_len;
1293 copyout(imgp->execpath, (void *)imgp->execpathp,
1294 execpath_len);
1295 }
1296
1297 /*
1298 * Prepare the canary for SSP.
1299 */
1300 arc4rand(canary, sizeof(canary), 0);
1301 imgp->canary = (uintptr_t)arginfo - szsigcode - execpath_len -
1302 sizeof(canary);
1303 copyout(canary, (void *)imgp->canary, sizeof(canary));
1304 imgp->canarylen = sizeof(canary);
1305
1306 /*
1307 * Prepare the pagesizes array.
1308 */
1309 imgp->pagesizes = (uintptr_t)arginfo - szsigcode - execpath_len -
1310 roundup(sizeof(canary), sizeof(char *)) - szps;
1311 copyout(pagesizes, (void *)imgp->pagesizes, szps);
1312 imgp->pagesizeslen = szps;
1313
1314 /*
1315 * If we have a valid auxargs ptr, prepare some room
1316 * on the stack.
1317 */
1318 if (imgp->auxargs) {
1319 /*
1320 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for
1321 * lower compatibility.
1322 */
1323 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size :
1324 (AT_COUNT * 2);
1325 /*
1326 * The '+ 2' is for the null pointers at the end of each of
1327 * the arg and env vector sets,and imgp->auxarg_size is room
1328 * for argument of Runtime loader.
1329 */
1330 vectp = (char **)(destp - (imgp->args->argc +
1331 imgp->args->envc + 2 + imgp->auxarg_size)
1332 * sizeof(char *));
1333 } else {
1334 /*
1335 * The '+ 2' is for the null pointers at the end of each of
1336 * the arg and env vector sets
1337 */
1338 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) *
1339 sizeof(char *));
1340 }
1341
1342 /*
1343 * vectp also becomes our initial stack base
1344 */
1345 stack_base = (register_t *)vectp;
1346
1347 stringp = imgp->args->begin_argv;
1348 argc = imgp->args->argc;
1349 envc = imgp->args->envc;
1350
1351 /*
1352 * Copy out strings - arguments and environment.
1353 */
1354 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace);
1355
1356 /*
1357 * Fill in "ps_strings" struct for ps, w, etc.
1358 */
1359 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp);
1360 suword32(&arginfo->ps_nargvstr, argc);
1361
1362 /*
1363 * Fill in argument portion of vector table.
1364 */
1365 for (; argc > 0; --argc) {
1366 suword(vectp++, (long)(intptr_t)destp);
1367 while (*stringp++ != 0)
1368 destp++;
1369 destp++;
1370 }
1371
1372 /* a null vector table pointer separates the argp's from the envp's */
1373 suword(vectp++, 0);
1374
1375 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp);
1376 suword32(&arginfo->ps_nenvstr, envc);
1377
1378 /*
1379 * Fill in environment portion of vector table.
1380 */
1381 for (; envc > 0; --envc) {
1382 suword(vectp++, (long)(intptr_t)destp);
1383 while (*stringp++ != 0)
1384 destp++;
1385 destp++;
1386 }
1387
1388 /* end of vector table is a null pointer */
1389 suword(vectp, 0);
1390
1391 return (stack_base);
1392 }
1393
1394 /*
1395 * Check permissions of file to execute.
1396 * Called with imgp->vp locked.
1397 * Return 0 for success or error code on failure.
1398 */
1399 int
1400 exec_check_permissions(imgp)
1401 struct image_params *imgp;
1402 {
1403 struct vnode *vp = imgp->vp;
1404 struct vattr *attr = imgp->attr;
1405 struct thread *td;
1406 int error, writecount;
1407
1408 td = curthread;
1409
1410 /* Get file attributes */
1411 error = VOP_GETATTR(vp, attr, td->td_ucred);
1412 if (error)
1413 return (error);
1414
1415 #ifdef MAC
1416 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp);
1417 if (error)
1418 return (error);
1419 #endif
1420
1421 /*
1422 * 1) Check if file execution is disabled for the filesystem that
1423 * this file resides on.
1424 * 2) Ensure that at least one execute bit is on. Otherwise, a
1425 * privileged user will always succeed, and we don't want this
1426 * to happen unless the file really is executable.
1427 * 3) Ensure that the file is a regular file.
1428 */
1429 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) ||
1430 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 ||
1431 (attr->va_type != VREG))
1432 return (EACCES);
1433
1434 /*
1435 * Zero length files can't be exec'd
1436 */
1437 if (attr->va_size == 0)
1438 return (ENOEXEC);
1439
1440 /*
1441 * Check for execute permission to file based on current credentials.
1442 */
1443 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td);
1444 if (error)
1445 return (error);
1446
1447 /*
1448 * Check number of open-for-writes on the file and deny execution
1449 * if there are any.
1450 */
1451 error = VOP_GET_WRITECOUNT(vp, &writecount);
1452 if (error != 0)
1453 return (error);
1454 if (writecount != 0)
1455 return (ETXTBSY);
1456
1457 /*
1458 * Call filesystem specific open routine (which does nothing in the
1459 * general case).
1460 */
1461 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL);
1462 if (error == 0)
1463 imgp->opened = 1;
1464 return (error);
1465 }
1466
1467 /*
1468 * Exec handler registration
1469 */
1470 int
1471 exec_register(execsw_arg)
1472 const struct execsw *execsw_arg;
1473 {
1474 const struct execsw **es, **xs, **newexecsw;
1475 int count = 2; /* New slot and trailing NULL */
1476
1477 if (execsw)
1478 for (es = execsw; *es; es++)
1479 count++;
1480 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
1481 if (newexecsw == NULL)
1482 return (ENOMEM);
1483 xs = newexecsw;
1484 if (execsw)
1485 for (es = execsw; *es; es++)
1486 *xs++ = *es;
1487 *xs++ = execsw_arg;
1488 *xs = NULL;
1489 if (execsw)
1490 free(execsw, M_TEMP);
1491 execsw = newexecsw;
1492 return (0);
1493 }
1494
1495 int
1496 exec_unregister(execsw_arg)
1497 const struct execsw *execsw_arg;
1498 {
1499 const struct execsw **es, **xs, **newexecsw;
1500 int count = 1;
1501
1502 if (execsw == NULL)
1503 panic("unregister with no handlers left?\n");
1504
1505 for (es = execsw; *es; es++) {
1506 if (*es == execsw_arg)
1507 break;
1508 }
1509 if (*es == NULL)
1510 return (ENOENT);
1511 for (es = execsw; *es; es++)
1512 if (*es != execsw_arg)
1513 count++;
1514 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
1515 if (newexecsw == NULL)
1516 return (ENOMEM);
1517 xs = newexecsw;
1518 for (es = execsw; *es; es++)
1519 if (*es != execsw_arg)
1520 *xs++ = *es;
1521 *xs = NULL;
1522 if (execsw)
1523 free(execsw, M_TEMP);
1524 execsw = newexecsw;
1525 return (0);
1526 }
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