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/9.0/sys/kern/kern_exec.c 226248 2011-10-11 13:18:44Z kib $");
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/sdt.h>
61 #include <sys/sf_buf.h>
62 #include <sys/syscallsubr.h>
63 #include <sys/sysent.h>
64 #include <sys/shm.h>
65 #include <sys/sysctl.h>
66 #include <sys/vnode.h>
67 #include <sys/stat.h>
68 #ifdef KTRACE
69 #include <sys/ktrace.h>
70 #endif
71
72 #include <vm/vm.h>
73 #include <vm/vm_param.h>
74 #include <vm/pmap.h>
75 #include <vm/vm_page.h>
76 #include <vm/vm_map.h>
77 #include <vm/vm_kern.h>
78 #include <vm/vm_extern.h>
79 #include <vm/vm_object.h>
80 #include <vm/vm_pager.h>
81
82 #ifdef HWPMC_HOOKS
83 #include <sys/pmckern.h>
84 #endif
85
86 #include <machine/reg.h>
87
88 #include <security/audit/audit.h>
89 #include <security/mac/mac_framework.h>
90
91 #ifdef KDTRACE_HOOKS
92 #include <sys/dtrace_bsd.h>
93 dtrace_execexit_func_t dtrace_fasttrap_exec;
94 #endif
95
96 SDT_PROVIDER_DECLARE(proc);
97 SDT_PROBE_DEFINE(proc, kernel, , exec, exec);
98 SDT_PROBE_ARGTYPE(proc, kernel, , exec, 0, "char *");
99 SDT_PROBE_DEFINE(proc, kernel, , exec_failure, exec-failure);
100 SDT_PROBE_ARGTYPE(proc, kernel, , exec_failure, 0, "int");
101 SDT_PROBE_DEFINE(proc, kernel, , exec_success, exec-success);
102 SDT_PROBE_ARGTYPE(proc, kernel, , exec_success, 0, "char *");
103
104 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments");
105
106 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS);
107 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS);
108 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS);
109 static int do_execve(struct thread *td, struct image_args *args,
110 struct mac *mac_p);
111
112 /* XXX This should be vm_size_t. */
113 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD,
114 NULL, 0, sysctl_kern_ps_strings, "LU", "");
115
116 /* XXX This should be vm_size_t. */
117 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD|
118 CTLFLAG_CAPRD, NULL, 0, sysctl_kern_usrstack, "LU", "");
119
120 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD,
121 NULL, 0, sysctl_kern_stackprot, "I", "");
122
123 u_long ps_arg_cache_limit = PAGE_SIZE / 16;
124 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW,
125 &ps_arg_cache_limit, 0, "");
126
127 static int map_at_zero = 0;
128 TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero);
129 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &map_at_zero, 0,
130 "Permit processes to map an object at virtual address 0.");
131
132 static int
133 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)
134 {
135 struct proc *p;
136 int error;
137
138 p = curproc;
139 #ifdef SCTL_MASK32
140 if (req->flags & SCTL_MASK32) {
141 unsigned int val;
142 val = (unsigned int)p->p_sysent->sv_psstrings;
143 error = SYSCTL_OUT(req, &val, sizeof(val));
144 } else
145 #endif
146 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings,
147 sizeof(p->p_sysent->sv_psstrings));
148 return error;
149 }
150
151 static int
152 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)
153 {
154 struct proc *p;
155 int error;
156
157 p = curproc;
158 #ifdef SCTL_MASK32
159 if (req->flags & SCTL_MASK32) {
160 unsigned int val;
161 val = (unsigned int)p->p_sysent->sv_usrstack;
162 error = SYSCTL_OUT(req, &val, sizeof(val));
163 } else
164 #endif
165 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack,
166 sizeof(p->p_sysent->sv_usrstack));
167 return error;
168 }
169
170 static int
171 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS)
172 {
173 struct proc *p;
174
175 p = curproc;
176 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot,
177 sizeof(p->p_sysent->sv_stackprot)));
178 }
179
180 /*
181 * Each of the items is a pointer to a `const struct execsw', hence the
182 * double pointer here.
183 */
184 static const struct execsw **execsw;
185
186 #ifndef _SYS_SYSPROTO_H_
187 struct execve_args {
188 char *fname;
189 char **argv;
190 char **envv;
191 };
192 #endif
193
194 int
195 sys_execve(td, uap)
196 struct thread *td;
197 struct execve_args /* {
198 char *fname;
199 char **argv;
200 char **envv;
201 } */ *uap;
202 {
203 int error;
204 struct image_args args;
205
206 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
207 uap->argv, uap->envv);
208 if (error == 0)
209 error = kern_execve(td, &args, NULL);
210 return (error);
211 }
212
213 #ifndef _SYS_SYSPROTO_H_
214 struct fexecve_args {
215 int fd;
216 char **argv;
217 char **envv;
218 }
219 #endif
220 int
221 sys_fexecve(struct thread *td, struct fexecve_args *uap)
222 {
223 int error;
224 struct image_args args;
225
226 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE,
227 uap->argv, uap->envv);
228 if (error == 0) {
229 args.fd = uap->fd;
230 error = kern_execve(td, &args, NULL);
231 }
232 return (error);
233 }
234
235 #ifndef _SYS_SYSPROTO_H_
236 struct __mac_execve_args {
237 char *fname;
238 char **argv;
239 char **envv;
240 struct mac *mac_p;
241 };
242 #endif
243
244 int
245 sys___mac_execve(td, uap)
246 struct thread *td;
247 struct __mac_execve_args /* {
248 char *fname;
249 char **argv;
250 char **envv;
251 struct mac *mac_p;
252 } */ *uap;
253 {
254 #ifdef MAC
255 int error;
256 struct image_args args;
257
258 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
259 uap->argv, uap->envv);
260 if (error == 0)
261 error = kern_execve(td, &args, uap->mac_p);
262 return (error);
263 #else
264 return (ENOSYS);
265 #endif
266 }
267
268 /*
269 * XXX: kern_execve has the astonishing property of not always returning to
270 * the caller. If sufficiently bad things happen during the call to
271 * do_execve(), it can end up calling exit1(); as a result, callers must
272 * avoid doing anything which they might need to undo (e.g., allocating
273 * memory).
274 */
275 int
276 kern_execve(td, args, mac_p)
277 struct thread *td;
278 struct image_args *args;
279 struct mac *mac_p;
280 {
281 struct proc *p = td->td_proc;
282 int error;
283
284 AUDIT_ARG_ARGV(args->begin_argv, args->argc,
285 args->begin_envv - args->begin_argv);
286 AUDIT_ARG_ENVV(args->begin_envv, args->envc,
287 args->endp - args->begin_envv);
288 if (p->p_flag & P_HADTHREADS) {
289 PROC_LOCK(p);
290 if (thread_single(SINGLE_BOUNDARY)) {
291 PROC_UNLOCK(p);
292 exec_free_args(args);
293 return (ERESTART); /* Try again later. */
294 }
295 PROC_UNLOCK(p);
296 }
297
298 error = do_execve(td, args, mac_p);
299
300 if (p->p_flag & P_HADTHREADS) {
301 PROC_LOCK(p);
302 /*
303 * If success, we upgrade to SINGLE_EXIT state to
304 * force other threads to suicide.
305 */
306 if (error == 0)
307 thread_single(SINGLE_EXIT);
308 else
309 thread_single_end();
310 PROC_UNLOCK(p);
311 }
312
313 return (error);
314 }
315
316 /*
317 * In-kernel implementation of execve(). All arguments are assumed to be
318 * userspace pointers from the passed thread.
319 */
320 static int
321 do_execve(td, args, mac_p)
322 struct thread *td;
323 struct image_args *args;
324 struct mac *mac_p;
325 {
326 struct proc *p = td->td_proc;
327 struct nameidata nd;
328 struct ucred *newcred = NULL, *oldcred;
329 struct uidinfo *euip;
330 register_t *stack_base;
331 int error, i;
332 struct image_params image_params, *imgp;
333 struct vattr attr;
334 int (*img_first)(struct image_params *);
335 struct pargs *oldargs = NULL, *newargs = NULL;
336 struct sigacts *oldsigacts, *newsigacts;
337 #ifdef KTRACE
338 struct vnode *tracevp = NULL;
339 struct ucred *tracecred = NULL;
340 #endif
341 struct vnode *textvp = NULL, *binvp = NULL;
342 int credential_changing;
343 int vfslocked;
344 int textset;
345 #ifdef MAC
346 struct label *interpvplabel = NULL;
347 int will_transition;
348 #endif
349 #ifdef HWPMC_HOOKS
350 struct pmckern_procexec pe;
351 #endif
352 static const char fexecv_proc_title[] = "(fexecv)";
353
354 vfslocked = 0;
355 imgp = &image_params;
356
357 /*
358 * Lock the process and set the P_INEXEC flag to indicate that
359 * it should be left alone until we're done here. This is
360 * necessary to avoid race conditions - e.g. in ptrace() -
361 * that might allow a local user to illicitly obtain elevated
362 * privileges.
363 */
364 PROC_LOCK(p);
365 KASSERT((p->p_flag & P_INEXEC) == 0,
366 ("%s(): process already has P_INEXEC flag", __func__));
367 p->p_flag |= P_INEXEC;
368 PROC_UNLOCK(p);
369
370 /*
371 * Initialize part of the common data
372 */
373 imgp->proc = p;
374 imgp->execlabel = NULL;
375 imgp->attr = &attr;
376 imgp->entry_addr = 0;
377 imgp->reloc_base = 0;
378 imgp->vmspace_destroyed = 0;
379 imgp->interpreted = 0;
380 imgp->opened = 0;
381 imgp->interpreter_name = NULL;
382 imgp->auxargs = NULL;
383 imgp->vp = NULL;
384 imgp->object = NULL;
385 imgp->firstpage = NULL;
386 imgp->ps_strings = 0;
387 imgp->auxarg_size = 0;
388 imgp->args = args;
389 imgp->execpath = imgp->freepath = NULL;
390 imgp->execpathp = 0;
391 imgp->canary = 0;
392 imgp->canarylen = 0;
393 imgp->pagesizes = 0;
394 imgp->pagesizeslen = 0;
395 imgp->stack_prot = 0;
396
397 #ifdef MAC
398 error = mac_execve_enter(imgp, mac_p);
399 if (error)
400 goto exec_fail;
401 #endif
402
403 imgp->image_header = NULL;
404
405 /*
406 * Translate the file name. namei() returns a vnode pointer
407 * in ni_vp amoung other things.
408 *
409 * XXXAUDIT: It would be desirable to also audit the name of the
410 * interpreter if this is an interpreted binary.
411 */
412 if (args->fname != NULL) {
413 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME
414 | MPSAFE | AUDITVNODE1, UIO_SYSSPACE, args->fname, td);
415 }
416
417 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 );
418
419 interpret:
420 if (args->fname != NULL) {
421 #ifdef CAPABILITY_MODE
422 /*
423 * While capability mode can't reach this point via direct
424 * path arguments to execve(), we also don't allow
425 * interpreters to be used in capability mode (for now).
426 * Catch indirect lookups and return a permissions error.
427 */
428 if (IN_CAPABILITY_MODE(td)) {
429 error = ECAPMODE;
430 goto exec_fail;
431 }
432 #endif
433 error = namei(&nd);
434 if (error)
435 goto exec_fail;
436
437 vfslocked = NDHASGIANT(&nd);
438 binvp = nd.ni_vp;
439 imgp->vp = binvp;
440 } else {
441 AUDIT_ARG_FD(args->fd);
442 /*
443 * Some might argue that CAP_READ and/or CAP_MMAP should also
444 * be required here; such arguments will be entertained.
445 */
446 error = fgetvp_read(td, args->fd, CAP_FEXECVE, &binvp);
447 if (error)
448 goto exec_fail;
449 vfslocked = VFS_LOCK_GIANT(binvp->v_mount);
450 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY);
451 AUDIT_ARG_VNODE1(binvp);
452 imgp->vp = binvp;
453 }
454
455 /*
456 * Check file permissions (also 'opens' file)
457 */
458 error = exec_check_permissions(imgp);
459 if (error)
460 goto exec_fail_dealloc;
461
462 imgp->object = imgp->vp->v_object;
463 if (imgp->object != NULL)
464 vm_object_reference(imgp->object);
465
466 /*
467 * Set VV_TEXT now so no one can write to the executable while we're
468 * activating it.
469 *
470 * Remember if this was set before and unset it in case this is not
471 * actually an executable image.
472 */
473 textset = imgp->vp->v_vflag & VV_TEXT;
474 imgp->vp->v_vflag |= VV_TEXT;
475
476 error = exec_map_first_page(imgp);
477 if (error)
478 goto exec_fail_dealloc;
479
480 imgp->proc->p_osrel = 0;
481 /*
482 * If the current process has a special image activator it
483 * wants to try first, call it. For example, emulating shell
484 * scripts differently.
485 */
486 error = -1;
487 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL)
488 error = img_first(imgp);
489
490 /*
491 * Loop through the list of image activators, calling each one.
492 * An activator returns -1 if there is no match, 0 on success,
493 * and an error otherwise.
494 */
495 for (i = 0; error == -1 && execsw[i]; ++i) {
496 if (execsw[i]->ex_imgact == NULL ||
497 execsw[i]->ex_imgact == img_first) {
498 continue;
499 }
500 error = (*execsw[i]->ex_imgact)(imgp);
501 }
502
503 if (error) {
504 if (error == -1) {
505 if (textset == 0)
506 imgp->vp->v_vflag &= ~VV_TEXT;
507 error = ENOEXEC;
508 }
509 goto exec_fail_dealloc;
510 }
511
512 /*
513 * Special interpreter operation, cleanup and loop up to try to
514 * activate the interpreter.
515 */
516 if (imgp->interpreted) {
517 exec_unmap_first_page(imgp);
518 /*
519 * VV_TEXT needs to be unset for scripts. There is a short
520 * period before we determine that something is a script where
521 * VV_TEXT will be set. The vnode lock is held over this
522 * entire period so nothing should illegitimately be blocked.
523 */
524 imgp->vp->v_vflag &= ~VV_TEXT;
525 /* free name buffer and old vnode */
526 if (args->fname != NULL)
527 NDFREE(&nd, NDF_ONLY_PNBUF);
528 #ifdef MAC
529 mac_execve_interpreter_enter(binvp, &interpvplabel);
530 #endif
531 if (imgp->opened) {
532 VOP_CLOSE(binvp, FREAD, td->td_ucred, td);
533 imgp->opened = 0;
534 }
535 vput(binvp);
536 vm_object_deallocate(imgp->object);
537 imgp->object = NULL;
538 VFS_UNLOCK_GIANT(vfslocked);
539 vfslocked = 0;
540 /* set new name to that of the interpreter */
541 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME | MPSAFE,
542 UIO_SYSSPACE, imgp->interpreter_name, td);
543 args->fname = imgp->interpreter_name;
544 goto interpret;
545 }
546
547 /*
548 * NB: We unlock the vnode here because it is believed that none
549 * of the sv_copyout_strings/sv_fixup operations require the vnode.
550 */
551 VOP_UNLOCK(imgp->vp, 0);
552
553 /*
554 * Do the best to calculate the full path to the image file.
555 */
556 if (imgp->auxargs != NULL &&
557 ((args->fname != NULL && args->fname[0] == '/') ||
558 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0))
559 imgp->execpath = args->fname;
560
561 /*
562 * Copy out strings (args and env) and initialize stack base
563 */
564 if (p->p_sysent->sv_copyout_strings)
565 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp);
566 else
567 stack_base = exec_copyout_strings(imgp);
568
569 /*
570 * If custom stack fixup routine present for this process
571 * let it do the stack setup.
572 * Else stuff argument count as first item on stack
573 */
574 if (p->p_sysent->sv_fixup != NULL)
575 (*p->p_sysent->sv_fixup)(&stack_base, imgp);
576 else
577 suword(--stack_base, imgp->args->argc);
578
579 /*
580 * For security and other reasons, the file descriptor table cannot
581 * be shared after an exec.
582 */
583 fdunshare(p, td);
584
585 /*
586 * Malloc things before we need locks.
587 */
588 newcred = crget();
589 euip = uifind(attr.va_uid);
590 i = imgp->args->begin_envv - imgp->args->begin_argv;
591 /* Cache arguments if they fit inside our allowance */
592 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) {
593 newargs = pargs_alloc(i);
594 bcopy(imgp->args->begin_argv, newargs->ar_args, i);
595 }
596
597 /* close files on exec */
598 fdcloseexec(td);
599 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
600
601 /* Get a reference to the vnode prior to locking the proc */
602 VREF(binvp);
603
604 /*
605 * For security and other reasons, signal handlers cannot
606 * be shared after an exec. The new process gets a copy of the old
607 * handlers. In execsigs(), the new process will have its signals
608 * reset.
609 */
610 PROC_LOCK(p);
611 oldcred = crcopysafe(p, newcred);
612 if (sigacts_shared(p->p_sigacts)) {
613 oldsigacts = p->p_sigacts;
614 PROC_UNLOCK(p);
615 newsigacts = sigacts_alloc();
616 sigacts_copy(newsigacts, oldsigacts);
617 PROC_LOCK(p);
618 p->p_sigacts = newsigacts;
619 } else
620 oldsigacts = NULL;
621
622 /* Stop profiling */
623 stopprofclock(p);
624
625 /* reset caught signals */
626 execsigs(p);
627
628 /* name this process - nameiexec(p, ndp) */
629 bzero(p->p_comm, sizeof(p->p_comm));
630 if (args->fname)
631 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm,
632 min(nd.ni_cnd.cn_namelen, MAXCOMLEN));
633 else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0)
634 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title));
635 bcopy(p->p_comm, td->td_name, sizeof(td->td_name));
636
637 /*
638 * mark as execed, wakeup the process that vforked (if any) and tell
639 * it that it now has its own resources back
640 */
641 p->p_flag |= P_EXEC;
642 if (p->p_pptr && (p->p_flag & P_PPWAIT)) {
643 p->p_flag &= ~P_PPWAIT;
644 cv_broadcast(&p->p_pwait);
645 }
646
647 /*
648 * Implement image setuid/setgid.
649 *
650 * Don't honor setuid/setgid if the filesystem prohibits it or if
651 * the process is being traced.
652 *
653 * We disable setuid/setgid/etc in compatibility mode on the basis
654 * that most setugid applications are not written with that
655 * environment in mind, and will therefore almost certainly operate
656 * incorrectly. In principle there's no reason that setugid
657 * applications might not be useful in capability mode, so we may want
658 * to reconsider this conservative design choice in the future.
659 *
660 * XXXMAC: For the time being, use NOSUID to also prohibit
661 * transitions on the file system.
662 */
663 credential_changing = 0;
664 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid !=
665 attr.va_uid;
666 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid !=
667 attr.va_gid;
668 #ifdef MAC
669 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp,
670 interpvplabel, imgp);
671 credential_changing |= will_transition;
672 #endif
673
674 if (credential_changing &&
675 #ifdef CAPABILITY_MODE
676 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) &&
677 #endif
678 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 &&
679 (p->p_flag & P_TRACED) == 0) {
680 /*
681 * Turn off syscall tracing for set-id programs, except for
682 * root. Record any set-id flags first to make sure that
683 * we do not regain any tracing during a possible block.
684 */
685 setsugid(p);
686
687 #ifdef KTRACE
688 if (priv_check_cred(oldcred, PRIV_DEBUG_DIFFCRED, 0))
689 ktrprocexec(p, &tracecred, &tracevp);
690 #endif
691 /*
692 * Close any file descriptors 0..2 that reference procfs,
693 * then make sure file descriptors 0..2 are in use.
694 *
695 * setugidsafety() may call closef() and then pfind()
696 * which may grab the process lock.
697 * fdcheckstd() may call falloc() which may block to
698 * allocate memory, so temporarily drop the process lock.
699 */
700 PROC_UNLOCK(p);
701 VOP_UNLOCK(imgp->vp, 0);
702 setugidsafety(td);
703 error = fdcheckstd(td);
704 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
705 if (error != 0)
706 goto done1;
707 PROC_LOCK(p);
708 /*
709 * Set the new credentials.
710 */
711 if (attr.va_mode & S_ISUID)
712 change_euid(newcred, euip);
713 if (attr.va_mode & S_ISGID)
714 change_egid(newcred, attr.va_gid);
715 #ifdef MAC
716 if (will_transition) {
717 mac_vnode_execve_transition(oldcred, newcred, imgp->vp,
718 interpvplabel, imgp);
719 }
720 #endif
721 /*
722 * Implement correct POSIX saved-id behavior.
723 *
724 * XXXMAC: Note that the current logic will save the
725 * uid and gid if a MAC domain transition occurs, even
726 * though maybe it shouldn't.
727 */
728 change_svuid(newcred, newcred->cr_uid);
729 change_svgid(newcred, newcred->cr_gid);
730 p->p_ucred = newcred;
731 newcred = NULL;
732 } else {
733 if (oldcred->cr_uid == oldcred->cr_ruid &&
734 oldcred->cr_gid == oldcred->cr_rgid)
735 p->p_flag &= ~P_SUGID;
736 /*
737 * Implement correct POSIX saved-id behavior.
738 *
739 * XXX: It's not clear that the existing behavior is
740 * POSIX-compliant. A number of sources indicate that the
741 * saved uid/gid should only be updated if the new ruid is
742 * not equal to the old ruid, or the new euid is not equal
743 * to the old euid and the new euid is not equal to the old
744 * ruid. The FreeBSD code always updates the saved uid/gid.
745 * Also, this code uses the new (replaced) euid and egid as
746 * the source, which may or may not be the right ones to use.
747 */
748 if (oldcred->cr_svuid != oldcred->cr_uid ||
749 oldcred->cr_svgid != oldcred->cr_gid) {
750 change_svuid(newcred, newcred->cr_uid);
751 change_svgid(newcred, newcred->cr_gid);
752 p->p_ucred = newcred;
753 newcred = NULL;
754 }
755 }
756
757 /*
758 * Store the vp for use in procfs. This vnode was referenced prior
759 * to locking the proc lock.
760 */
761 textvp = p->p_textvp;
762 p->p_textvp = binvp;
763
764 #ifdef KDTRACE_HOOKS
765 /*
766 * Tell the DTrace fasttrap provider about the exec if it
767 * has declared an interest.
768 */
769 if (dtrace_fasttrap_exec)
770 dtrace_fasttrap_exec(p);
771 #endif
772
773 /*
774 * Notify others that we exec'd, and clear the P_INEXEC flag
775 * as we're now a bona fide freshly-execed process.
776 */
777 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC);
778 p->p_flag &= ~P_INEXEC;
779
780 /* clear "fork but no exec" flag, as we _are_ execing */
781 p->p_acflag &= ~AFORK;
782
783 /*
784 * Free any previous argument cache and replace it with
785 * the new argument cache, if any.
786 */
787 oldargs = p->p_args;
788 p->p_args = newargs;
789 newargs = NULL;
790
791 #ifdef HWPMC_HOOKS
792 /*
793 * Check if system-wide sampling is in effect or if the
794 * current process is using PMCs. If so, do exec() time
795 * processing. This processing needs to happen AFTER the
796 * P_INEXEC flag is cleared.
797 *
798 * The proc lock needs to be released before taking the PMC
799 * SX.
800 */
801 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) {
802 PROC_UNLOCK(p);
803 VOP_UNLOCK(imgp->vp, 0);
804 pe.pm_credentialschanged = credential_changing;
805 pe.pm_entryaddr = imgp->entry_addr;
806
807 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe);
808 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
809 } else
810 PROC_UNLOCK(p);
811 #else /* !HWPMC_HOOKS */
812 PROC_UNLOCK(p);
813 #endif
814
815 /* Set values passed into the program in registers. */
816 if (p->p_sysent->sv_setregs)
817 (*p->p_sysent->sv_setregs)(td, imgp,
818 (u_long)(uintptr_t)stack_base);
819 else
820 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base);
821
822 vfs_mark_atime(imgp->vp, td->td_ucred);
823
824 SDT_PROBE(proc, kernel, , exec_success, args->fname, 0, 0, 0, 0);
825
826 done1:
827 /*
828 * Free any resources malloc'd earlier that we didn't use.
829 */
830 uifree(euip);
831 if (newcred == NULL)
832 crfree(oldcred);
833 else
834 crfree(newcred);
835 VOP_UNLOCK(imgp->vp, 0);
836
837 /*
838 * Handle deferred decrement of ref counts.
839 */
840 if (textvp != NULL) {
841 int tvfslocked;
842
843 tvfslocked = VFS_LOCK_GIANT(textvp->v_mount);
844 vrele(textvp);
845 VFS_UNLOCK_GIANT(tvfslocked);
846 }
847 if (binvp && error != 0)
848 vrele(binvp);
849 #ifdef KTRACE
850 if (tracevp != NULL) {
851 int tvfslocked;
852
853 tvfslocked = VFS_LOCK_GIANT(tracevp->v_mount);
854 vrele(tracevp);
855 VFS_UNLOCK_GIANT(tvfslocked);
856 }
857 if (tracecred != NULL)
858 crfree(tracecred);
859 #endif
860 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
861 pargs_drop(oldargs);
862 pargs_drop(newargs);
863 if (oldsigacts != NULL)
864 sigacts_free(oldsigacts);
865
866 exec_fail_dealloc:
867
868 /*
869 * free various allocated resources
870 */
871 if (imgp->firstpage != NULL)
872 exec_unmap_first_page(imgp);
873
874 if (imgp->vp != NULL) {
875 if (args->fname)
876 NDFREE(&nd, NDF_ONLY_PNBUF);
877 if (imgp->opened)
878 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td);
879 vput(imgp->vp);
880 }
881
882 if (imgp->object != NULL)
883 vm_object_deallocate(imgp->object);
884
885 free(imgp->freepath, M_TEMP);
886
887 if (error == 0) {
888 PROC_LOCK(p);
889 td->td_dbgflags |= TDB_EXEC;
890 PROC_UNLOCK(p);
891
892 /*
893 * Stop the process here if its stop event mask has
894 * the S_EXEC bit set.
895 */
896 STOPEVENT(p, S_EXEC, 0);
897 goto done2;
898 }
899
900 exec_fail:
901 /* we're done here, clear P_INEXEC */
902 PROC_LOCK(p);
903 p->p_flag &= ~P_INEXEC;
904 PROC_UNLOCK(p);
905
906 SDT_PROBE(proc, kernel, , exec_failure, error, 0, 0, 0, 0);
907
908 done2:
909 #ifdef MAC
910 mac_execve_exit(imgp);
911 mac_execve_interpreter_exit(interpvplabel);
912 #endif
913 VFS_UNLOCK_GIANT(vfslocked);
914 exec_free_args(args);
915
916 if (error && imgp->vmspace_destroyed) {
917 /* sorry, no more process anymore. exit gracefully */
918 exit1(td, W_EXITCODE(0, SIGABRT));
919 /* NOT REACHED */
920 }
921
922 #ifdef KTRACE
923 if (error == 0)
924 ktrprocctor(p);
925 #endif
926
927 return (error);
928 }
929
930 int
931 exec_map_first_page(imgp)
932 struct image_params *imgp;
933 {
934 int rv, i;
935 int initial_pagein;
936 vm_page_t ma[VM_INITIAL_PAGEIN];
937 vm_object_t object;
938
939 if (imgp->firstpage != NULL)
940 exec_unmap_first_page(imgp);
941
942 object = imgp->vp->v_object;
943 if (object == NULL)
944 return (EACCES);
945 VM_OBJECT_LOCK(object);
946 #if VM_NRESERVLEVEL > 0
947 if ((object->flags & OBJ_COLORED) == 0) {
948 object->flags |= OBJ_COLORED;
949 object->pg_color = 0;
950 }
951 #endif
952 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
953 if (ma[0]->valid != VM_PAGE_BITS_ALL) {
954 initial_pagein = VM_INITIAL_PAGEIN;
955 if (initial_pagein > object->size)
956 initial_pagein = object->size;
957 for (i = 1; i < initial_pagein; i++) {
958 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) {
959 if (ma[i]->valid)
960 break;
961 if ((ma[i]->oflags & VPO_BUSY) || ma[i]->busy)
962 break;
963 vm_page_busy(ma[i]);
964 } else {
965 ma[i] = vm_page_alloc(object, i,
966 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED);
967 if (ma[i] == NULL)
968 break;
969 }
970 }
971 initial_pagein = i;
972 rv = vm_pager_get_pages(object, ma, initial_pagein, 0);
973 ma[0] = vm_page_lookup(object, 0);
974 if ((rv != VM_PAGER_OK) || (ma[0] == NULL)) {
975 if (ma[0] != NULL) {
976 vm_page_lock(ma[0]);
977 vm_page_free(ma[0]);
978 vm_page_unlock(ma[0]);
979 }
980 VM_OBJECT_UNLOCK(object);
981 return (EIO);
982 }
983 }
984 vm_page_lock(ma[0]);
985 vm_page_hold(ma[0]);
986 vm_page_unlock(ma[0]);
987 vm_page_wakeup(ma[0]);
988 VM_OBJECT_UNLOCK(object);
989
990 imgp->firstpage = sf_buf_alloc(ma[0], 0);
991 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage);
992
993 return (0);
994 }
995
996 void
997 exec_unmap_first_page(imgp)
998 struct image_params *imgp;
999 {
1000 vm_page_t m;
1001
1002 if (imgp->firstpage != NULL) {
1003 m = sf_buf_page(imgp->firstpage);
1004 sf_buf_free(imgp->firstpage);
1005 imgp->firstpage = NULL;
1006 vm_page_lock(m);
1007 vm_page_unhold(m);
1008 vm_page_unlock(m);
1009 }
1010 }
1011
1012 /*
1013 * Destroy old address space, and allocate a new stack
1014 * The new stack is only SGROWSIZ large because it is grown
1015 * automatically in trap.c.
1016 */
1017 int
1018 exec_new_vmspace(imgp, sv)
1019 struct image_params *imgp;
1020 struct sysentvec *sv;
1021 {
1022 int error;
1023 struct proc *p = imgp->proc;
1024 struct vmspace *vmspace = p->p_vmspace;
1025 vm_object_t obj;
1026 vm_offset_t sv_minuser, stack_addr;
1027 vm_map_t map;
1028 u_long ssiz;
1029
1030 imgp->vmspace_destroyed = 1;
1031 imgp->sysent = sv;
1032
1033 /* May be called with Giant held */
1034 EVENTHANDLER_INVOKE(process_exec, p, imgp);
1035
1036 /*
1037 * Blow away entire process VM, if address space not shared,
1038 * otherwise, create a new VM space so that other threads are
1039 * not disrupted
1040 */
1041 map = &vmspace->vm_map;
1042 if (map_at_zero)
1043 sv_minuser = sv->sv_minuser;
1044 else
1045 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE);
1046 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser &&
1047 vm_map_max(map) == sv->sv_maxuser) {
1048 shmexit(vmspace);
1049 pmap_remove_pages(vmspace_pmap(vmspace));
1050 vm_map_remove(map, vm_map_min(map), vm_map_max(map));
1051 } else {
1052 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser);
1053 if (error)
1054 return (error);
1055 vmspace = p->p_vmspace;
1056 map = &vmspace->vm_map;
1057 }
1058
1059 /* Map a shared page */
1060 obj = sv->sv_shared_page_obj;
1061 if (obj != NULL) {
1062 vm_object_reference(obj);
1063 error = vm_map_fixed(map, obj, 0,
1064 sv->sv_shared_page_base, sv->sv_shared_page_len,
1065 VM_PROT_READ | VM_PROT_EXECUTE, VM_PROT_ALL,
1066 MAP_COPY_ON_WRITE | MAP_ACC_NO_CHARGE);
1067 if (error) {
1068 vm_object_deallocate(obj);
1069 return (error);
1070 }
1071 }
1072
1073 /* Allocate a new stack */
1074 if (sv->sv_maxssiz != NULL)
1075 ssiz = *sv->sv_maxssiz;
1076 else
1077 ssiz = maxssiz;
1078 stack_addr = sv->sv_usrstack - ssiz;
1079 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz,
1080 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot :
1081 sv->sv_stackprot,
1082 VM_PROT_ALL, MAP_STACK_GROWS_DOWN);
1083 if (error)
1084 return (error);
1085
1086 #ifdef __ia64__
1087 /* Allocate a new register stack */
1088 stack_addr = IA64_BACKINGSTORE;
1089 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz,
1090 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP);
1091 if (error)
1092 return (error);
1093 #endif
1094
1095 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the
1096 * VM_STACK case, but they are still used to monitor the size of the
1097 * process stack so we can check the stack rlimit.
1098 */
1099 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT;
1100 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz;
1101
1102 return (0);
1103 }
1104
1105 /*
1106 * Copy out argument and environment strings from the old process address
1107 * space into the temporary string buffer.
1108 */
1109 int
1110 exec_copyin_args(struct image_args *args, char *fname,
1111 enum uio_seg segflg, char **argv, char **envv)
1112 {
1113 char *argp, *envp;
1114 int error;
1115 size_t length;
1116
1117 bzero(args, sizeof(*args));
1118 if (argv == NULL)
1119 return (EFAULT);
1120
1121 /*
1122 * Allocate demand-paged memory for the file name, argument, and
1123 * environment strings.
1124 */
1125 error = exec_alloc_args(args);
1126 if (error != 0)
1127 return (error);
1128
1129 /*
1130 * Copy the file name.
1131 */
1132 if (fname != NULL) {
1133 args->fname = args->buf;
1134 error = (segflg == UIO_SYSSPACE) ?
1135 copystr(fname, args->fname, PATH_MAX, &length) :
1136 copyinstr(fname, args->fname, PATH_MAX, &length);
1137 if (error != 0)
1138 goto err_exit;
1139 } else
1140 length = 0;
1141
1142 args->begin_argv = args->buf + length;
1143 args->endp = args->begin_argv;
1144 args->stringspace = ARG_MAX;
1145
1146 /*
1147 * extract arguments first
1148 */
1149 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) {
1150 if (argp == (caddr_t) -1) {
1151 error = EFAULT;
1152 goto err_exit;
1153 }
1154 if ((error = copyinstr(argp, args->endp,
1155 args->stringspace, &length))) {
1156 if (error == ENAMETOOLONG)
1157 error = E2BIG;
1158 goto err_exit;
1159 }
1160 args->stringspace -= length;
1161 args->endp += length;
1162 args->argc++;
1163 }
1164
1165 args->begin_envv = args->endp;
1166
1167 /*
1168 * extract environment strings
1169 */
1170 if (envv) {
1171 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) {
1172 if (envp == (caddr_t)-1) {
1173 error = EFAULT;
1174 goto err_exit;
1175 }
1176 if ((error = copyinstr(envp, args->endp,
1177 args->stringspace, &length))) {
1178 if (error == ENAMETOOLONG)
1179 error = E2BIG;
1180 goto err_exit;
1181 }
1182 args->stringspace -= length;
1183 args->endp += length;
1184 args->envc++;
1185 }
1186 }
1187
1188 return (0);
1189
1190 err_exit:
1191 exec_free_args(args);
1192 return (error);
1193 }
1194
1195 /*
1196 * Allocate temporary demand-paged, zero-filled memory for the file name,
1197 * argument, and environment strings. Returns zero if the allocation succeeds
1198 * and ENOMEM otherwise.
1199 */
1200 int
1201 exec_alloc_args(struct image_args *args)
1202 {
1203
1204 args->buf = (char *)kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX);
1205 return (args->buf != NULL ? 0 : ENOMEM);
1206 }
1207
1208 void
1209 exec_free_args(struct image_args *args)
1210 {
1211
1212 if (args->buf != NULL) {
1213 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf,
1214 PATH_MAX + ARG_MAX);
1215 args->buf = NULL;
1216 }
1217 if (args->fname_buf != NULL) {
1218 free(args->fname_buf, M_TEMP);
1219 args->fname_buf = NULL;
1220 }
1221 }
1222
1223 /*
1224 * Copy strings out to the new process address space, constructing new arg
1225 * and env vector tables. Return a pointer to the base so that it can be used
1226 * as the initial stack pointer.
1227 */
1228 register_t *
1229 exec_copyout_strings(imgp)
1230 struct image_params *imgp;
1231 {
1232 int argc, envc;
1233 char **vectp;
1234 char *stringp, *destp;
1235 register_t *stack_base;
1236 struct ps_strings *arginfo;
1237 struct proc *p;
1238 size_t execpath_len;
1239 int szsigcode, szps;
1240 char canary[sizeof(long) * 8];
1241
1242 szps = sizeof(pagesizes[0]) * MAXPAGESIZES;
1243 /*
1244 * Calculate string base and vector table pointers.
1245 * Also deal with signal trampoline code for this exec type.
1246 */
1247 if (imgp->execpath != NULL && imgp->auxargs != NULL)
1248 execpath_len = strlen(imgp->execpath) + 1;
1249 else
1250 execpath_len = 0;
1251 p = imgp->proc;
1252 szsigcode = 0;
1253 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings;
1254 if (p->p_sysent->sv_sigcode_base == 0) {
1255 if (p->p_sysent->sv_szsigcode != NULL)
1256 szsigcode = *(p->p_sysent->sv_szsigcode);
1257 }
1258 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE -
1259 roundup(execpath_len, sizeof(char *)) -
1260 roundup(sizeof(canary), sizeof(char *)) -
1261 roundup(szps, sizeof(char *)) -
1262 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *));
1263
1264 /*
1265 * install sigcode
1266 */
1267 if (szsigcode != 0)
1268 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo -
1269 szsigcode), szsigcode);
1270
1271 /*
1272 * Copy the image path for the rtld.
1273 */
1274 if (execpath_len != 0) {
1275 imgp->execpathp = (uintptr_t)arginfo - szsigcode - execpath_len;
1276 copyout(imgp->execpath, (void *)imgp->execpathp,
1277 execpath_len);
1278 }
1279
1280 /*
1281 * Prepare the canary for SSP.
1282 */
1283 arc4rand(canary, sizeof(canary), 0);
1284 imgp->canary = (uintptr_t)arginfo - szsigcode - execpath_len -
1285 sizeof(canary);
1286 copyout(canary, (void *)imgp->canary, sizeof(canary));
1287 imgp->canarylen = sizeof(canary);
1288
1289 /*
1290 * Prepare the pagesizes array.
1291 */
1292 imgp->pagesizes = (uintptr_t)arginfo - szsigcode - execpath_len -
1293 roundup(sizeof(canary), sizeof(char *)) - szps;
1294 copyout(pagesizes, (void *)imgp->pagesizes, szps);
1295 imgp->pagesizeslen = szps;
1296
1297 /*
1298 * If we have a valid auxargs ptr, prepare some room
1299 * on the stack.
1300 */
1301 if (imgp->auxargs) {
1302 /*
1303 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for
1304 * lower compatibility.
1305 */
1306 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size :
1307 (AT_COUNT * 2);
1308 /*
1309 * The '+ 2' is for the null pointers at the end of each of
1310 * the arg and env vector sets,and imgp->auxarg_size is room
1311 * for argument of Runtime loader.
1312 */
1313 vectp = (char **)(destp - (imgp->args->argc +
1314 imgp->args->envc + 2 + imgp->auxarg_size)
1315 * sizeof(char *));
1316 } else {
1317 /*
1318 * The '+ 2' is for the null pointers at the end of each of
1319 * the arg and env vector sets
1320 */
1321 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) *
1322 sizeof(char *));
1323 }
1324
1325 /*
1326 * vectp also becomes our initial stack base
1327 */
1328 stack_base = (register_t *)vectp;
1329
1330 stringp = imgp->args->begin_argv;
1331 argc = imgp->args->argc;
1332 envc = imgp->args->envc;
1333
1334 /*
1335 * Copy out strings - arguments and environment.
1336 */
1337 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace);
1338
1339 /*
1340 * Fill in "ps_strings" struct for ps, w, etc.
1341 */
1342 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp);
1343 suword32(&arginfo->ps_nargvstr, argc);
1344
1345 /*
1346 * Fill in argument portion of vector table.
1347 */
1348 for (; argc > 0; --argc) {
1349 suword(vectp++, (long)(intptr_t)destp);
1350 while (*stringp++ != 0)
1351 destp++;
1352 destp++;
1353 }
1354
1355 /* a null vector table pointer separates the argp's from the envp's */
1356 suword(vectp++, 0);
1357
1358 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp);
1359 suword32(&arginfo->ps_nenvstr, envc);
1360
1361 /*
1362 * Fill in environment portion of vector table.
1363 */
1364 for (; envc > 0; --envc) {
1365 suword(vectp++, (long)(intptr_t)destp);
1366 while (*stringp++ != 0)
1367 destp++;
1368 destp++;
1369 }
1370
1371 /* end of vector table is a null pointer */
1372 suword(vectp, 0);
1373
1374 return (stack_base);
1375 }
1376
1377 /*
1378 * Check permissions of file to execute.
1379 * Called with imgp->vp locked.
1380 * Return 0 for success or error code on failure.
1381 */
1382 int
1383 exec_check_permissions(imgp)
1384 struct image_params *imgp;
1385 {
1386 struct vnode *vp = imgp->vp;
1387 struct vattr *attr = imgp->attr;
1388 struct thread *td;
1389 int error;
1390
1391 td = curthread;
1392
1393 /* Get file attributes */
1394 error = VOP_GETATTR(vp, attr, td->td_ucred);
1395 if (error)
1396 return (error);
1397
1398 #ifdef MAC
1399 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp);
1400 if (error)
1401 return (error);
1402 #endif
1403
1404 /*
1405 * 1) Check if file execution is disabled for the filesystem that
1406 * this file resides on.
1407 * 2) Ensure that at least one execute bit is on. Otherwise, a
1408 * privileged user will always succeed, and we don't want this
1409 * to happen unless the file really is executable.
1410 * 3) Ensure that the file is a regular file.
1411 */
1412 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) ||
1413 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 ||
1414 (attr->va_type != VREG))
1415 return (EACCES);
1416
1417 /*
1418 * Zero length files can't be exec'd
1419 */
1420 if (attr->va_size == 0)
1421 return (ENOEXEC);
1422
1423 /*
1424 * Check for execute permission to file based on current credentials.
1425 */
1426 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td);
1427 if (error)
1428 return (error);
1429
1430 /*
1431 * Check number of open-for-writes on the file and deny execution
1432 * if there are any.
1433 */
1434 if (vp->v_writecount)
1435 return (ETXTBSY);
1436
1437 /*
1438 * Call filesystem specific open routine (which does nothing in the
1439 * general case).
1440 */
1441 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL);
1442 if (error == 0)
1443 imgp->opened = 1;
1444 return (error);
1445 }
1446
1447 /*
1448 * Exec handler registration
1449 */
1450 int
1451 exec_register(execsw_arg)
1452 const struct execsw *execsw_arg;
1453 {
1454 const struct execsw **es, **xs, **newexecsw;
1455 int count = 2; /* New slot and trailing NULL */
1456
1457 if (execsw)
1458 for (es = execsw; *es; es++)
1459 count++;
1460 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
1461 if (newexecsw == NULL)
1462 return (ENOMEM);
1463 xs = newexecsw;
1464 if (execsw)
1465 for (es = execsw; *es; es++)
1466 *xs++ = *es;
1467 *xs++ = execsw_arg;
1468 *xs = NULL;
1469 if (execsw)
1470 free(execsw, M_TEMP);
1471 execsw = newexecsw;
1472 return (0);
1473 }
1474
1475 int
1476 exec_unregister(execsw_arg)
1477 const struct execsw *execsw_arg;
1478 {
1479 const struct execsw **es, **xs, **newexecsw;
1480 int count = 1;
1481
1482 if (execsw == NULL)
1483 panic("unregister with no handlers left?\n");
1484
1485 for (es = execsw; *es; es++) {
1486 if (*es == execsw_arg)
1487 break;
1488 }
1489 if (*es == NULL)
1490 return (ENOENT);
1491 for (es = execsw; *es; es++)
1492 if (*es != execsw_arg)
1493 count++;
1494 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
1495 if (newexecsw == NULL)
1496 return (ENOMEM);
1497 xs = newexecsw;
1498 for (es = execsw; *es; es++)
1499 if (*es != execsw_arg)
1500 *xs++ = *es;
1501 *xs = NULL;
1502 if (execsw)
1503 free(execsw, M_TEMP);
1504 execsw = newexecsw;
1505 return (0);
1506 }
1507
1508 static vm_object_t shared_page_obj;
1509 static int shared_page_free;
1510
1511 int
1512 shared_page_fill(int size, int align, const char *data)
1513 {
1514 vm_page_t m;
1515 struct sf_buf *s;
1516 vm_offset_t sk;
1517 int res;
1518
1519 VM_OBJECT_LOCK(shared_page_obj);
1520 m = vm_page_grab(shared_page_obj, 0, VM_ALLOC_RETRY);
1521 res = roundup(shared_page_free, align);
1522 if (res + size >= IDX_TO_OFF(shared_page_obj->size))
1523 res = -1;
1524 else {
1525 VM_OBJECT_UNLOCK(shared_page_obj);
1526 s = sf_buf_alloc(m, SFB_DEFAULT);
1527 sk = sf_buf_kva(s);
1528 bcopy(data, (void *)(sk + res), size);
1529 shared_page_free = res + size;
1530 sf_buf_free(s);
1531 VM_OBJECT_LOCK(shared_page_obj);
1532 }
1533 vm_page_wakeup(m);
1534 VM_OBJECT_UNLOCK(shared_page_obj);
1535 return (res);
1536 }
1537
1538 static void
1539 shared_page_init(void *dummy __unused)
1540 {
1541 vm_page_t m;
1542
1543 shared_page_obj = vm_pager_allocate(OBJT_PHYS, 0, PAGE_SIZE,
1544 VM_PROT_DEFAULT, 0, NULL);
1545 VM_OBJECT_LOCK(shared_page_obj);
1546 m = vm_page_grab(shared_page_obj, 0, VM_ALLOC_RETRY | VM_ALLOC_NOBUSY |
1547 VM_ALLOC_ZERO);
1548 m->valid = VM_PAGE_BITS_ALL;
1549 VM_OBJECT_UNLOCK(shared_page_obj);
1550 }
1551
1552 SYSINIT(shp, SI_SUB_EXEC, SI_ORDER_FIRST, (sysinit_cfunc_t)shared_page_init,
1553 NULL);
1554
1555 void
1556 exec_sysvec_init(void *param)
1557 {
1558 struct sysentvec *sv;
1559
1560 sv = (struct sysentvec *)param;
1561
1562 if ((sv->sv_flags & SV_SHP) == 0)
1563 return;
1564 sv->sv_shared_page_obj = shared_page_obj;
1565 sv->sv_sigcode_base = sv->sv_shared_page_base +
1566 shared_page_fill(*(sv->sv_szsigcode), 16, sv->sv_sigcode);
1567 }
Cache object: 489a34c6d41678331be79f6dea8774ad
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