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: stable/9/sys/kern/kern_exec.c 289800 2015-10-23 07:44:03Z avg $");
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_DEFINE1(proc, kernel, , exec, "char *");
99 SDT_PROBE_DEFINE1(proc, kernel, , exec__failure, "int");
100 SDT_PROBE_DEFINE1(proc, kernel, , exec__success, "char *");
101
102 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments");
103
104 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS);
105 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS);
106 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS);
107 static int do_execve(struct thread *td, struct image_args *args,
108 struct mac *mac_p);
109
110 /* XXX This should be vm_size_t. */
111 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD,
112 NULL, 0, sysctl_kern_ps_strings, "LU", "");
113
114 /* XXX This should be vm_size_t. */
115 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD|
116 CTLFLAG_CAPRD, NULL, 0, sysctl_kern_usrstack, "LU", "");
117
118 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD,
119 NULL, 0, sysctl_kern_stackprot, "I", "");
120
121 u_long ps_arg_cache_limit = PAGE_SIZE / 16;
122 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW,
123 &ps_arg_cache_limit, 0, "");
124
125 static int disallow_high_osrel;
126 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW,
127 &disallow_high_osrel, 0,
128 "Disallow execution of binaries built for higher version of the world");
129
130 static int map_at_zero = 0;
131 TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero);
132 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &map_at_zero, 0,
133 "Permit processes to map an object at virtual address 0.");
134
135 static int
sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)136 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)
137 {
138 struct proc *p;
139 int error;
140
141 p = curproc;
142 #ifdef SCTL_MASK32
143 if (req->flags & SCTL_MASK32) {
144 unsigned int val;
145 val = (unsigned int)p->p_sysent->sv_psstrings;
146 error = SYSCTL_OUT(req, &val, sizeof(val));
147 } else
148 #endif
149 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings,
150 sizeof(p->p_sysent->sv_psstrings));
151 return error;
152 }
153
154 static int
sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)155 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)
156 {
157 struct proc *p;
158 int error;
159
160 p = curproc;
161 #ifdef SCTL_MASK32
162 if (req->flags & SCTL_MASK32) {
163 unsigned int val;
164 val = (unsigned int)p->p_sysent->sv_usrstack;
165 error = SYSCTL_OUT(req, &val, sizeof(val));
166 } else
167 #endif
168 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack,
169 sizeof(p->p_sysent->sv_usrstack));
170 return error;
171 }
172
173 static int
sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS)174 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS)
175 {
176 struct proc *p;
177
178 p = curproc;
179 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot,
180 sizeof(p->p_sysent->sv_stackprot)));
181 }
182
183 /*
184 * Each of the items is a pointer to a `const struct execsw', hence the
185 * double pointer here.
186 */
187 static const struct execsw **execsw;
188
189 #ifndef _SYS_SYSPROTO_H_
190 struct execve_args {
191 char *fname;
192 char **argv;
193 char **envv;
194 };
195 #endif
196
197 int
sys_execve(td,uap)198 sys_execve(td, uap)
199 struct thread *td;
200 struct execve_args /* {
201 char *fname;
202 char **argv;
203 char **envv;
204 } */ *uap;
205 {
206 int error;
207 struct image_args args;
208
209 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
210 uap->argv, uap->envv);
211 if (error == 0)
212 error = kern_execve(td, &args, NULL);
213 return (error);
214 }
215
216 #ifndef _SYS_SYSPROTO_H_
217 struct fexecve_args {
218 int fd;
219 char **argv;
220 char **envv;
221 }
222 #endif
223 int
sys_fexecve(struct thread * td,struct fexecve_args * uap)224 sys_fexecve(struct thread *td, struct fexecve_args *uap)
225 {
226 int error;
227 struct image_args args;
228
229 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE,
230 uap->argv, uap->envv);
231 if (error == 0) {
232 args.fd = uap->fd;
233 error = kern_execve(td, &args, NULL);
234 }
235 return (error);
236 }
237
238 #ifndef _SYS_SYSPROTO_H_
239 struct __mac_execve_args {
240 char *fname;
241 char **argv;
242 char **envv;
243 struct mac *mac_p;
244 };
245 #endif
246
247 int
sys___mac_execve(td,uap)248 sys___mac_execve(td, uap)
249 struct thread *td;
250 struct __mac_execve_args /* {
251 char *fname;
252 char **argv;
253 char **envv;
254 struct mac *mac_p;
255 } */ *uap;
256 {
257 #ifdef MAC
258 int error;
259 struct image_args args;
260
261 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
262 uap->argv, uap->envv);
263 if (error == 0)
264 error = kern_execve(td, &args, uap->mac_p);
265 return (error);
266 #else
267 return (ENOSYS);
268 #endif
269 }
270
271 /*
272 * XXX: kern_execve has the astonishing property of not always returning to
273 * the caller. If sufficiently bad things happen during the call to
274 * do_execve(), it can end up calling exit1(); as a result, callers must
275 * avoid doing anything which they might need to undo (e.g., allocating
276 * memory).
277 */
278 int
kern_execve(td,args,mac_p)279 kern_execve(td, args, mac_p)
280 struct thread *td;
281 struct image_args *args;
282 struct mac *mac_p;
283 {
284 struct proc *p = td->td_proc;
285 struct vmspace *oldvmspace;
286 int error;
287
288 AUDIT_ARG_ARGV(args->begin_argv, args->argc,
289 args->begin_envv - args->begin_argv);
290 AUDIT_ARG_ENVV(args->begin_envv, args->envc,
291 args->endp - args->begin_envv);
292 if (p->p_flag & P_HADTHREADS) {
293 PROC_LOCK(p);
294 if (thread_single(SINGLE_BOUNDARY)) {
295 PROC_UNLOCK(p);
296 exec_free_args(args);
297 return (ERESTART); /* Try again later. */
298 }
299 PROC_UNLOCK(p);
300 }
301
302 KASSERT((td->td_pflags & TDP_EXECVMSPC) == 0, ("nested execve"));
303 oldvmspace = td->td_proc->p_vmspace;
304 error = do_execve(td, args, mac_p);
305
306 if (p->p_flag & P_HADTHREADS) {
307 PROC_LOCK(p);
308 /*
309 * If success, we upgrade to SINGLE_EXIT state to
310 * force other threads to suicide.
311 */
312 if (error == 0)
313 thread_single(SINGLE_EXIT);
314 else
315 thread_single_end();
316 PROC_UNLOCK(p);
317 }
318 if ((td->td_pflags & TDP_EXECVMSPC) != 0) {
319 KASSERT(td->td_proc->p_vmspace != oldvmspace,
320 ("oldvmspace still used"));
321 vmspace_free(oldvmspace);
322 td->td_pflags &= ~TDP_EXECVMSPC;
323 }
324
325 return (error);
326 }
327
328 /*
329 * In-kernel implementation of execve(). All arguments are assumed to be
330 * userspace pointers from the passed thread.
331 */
332 static int
do_execve(td,args,mac_p)333 do_execve(td, args, mac_p)
334 struct thread *td;
335 struct image_args *args;
336 struct mac *mac_p;
337 {
338 struct proc *p = td->td_proc;
339 struct nameidata nd;
340 struct ucred *newcred = NULL, *oldcred;
341 struct uidinfo *euip;
342 register_t *stack_base;
343 int error, i;
344 struct image_params image_params, *imgp;
345 struct vattr attr;
346 int (*img_first)(struct image_params *);
347 struct pargs *oldargs = NULL, *newargs = NULL;
348 struct sigacts *oldsigacts, *newsigacts;
349 #ifdef KTRACE
350 struct vnode *tracevp = NULL;
351 struct ucred *tracecred = NULL;
352 #endif
353 struct vnode *textvp = NULL, *binvp = NULL;
354 int credential_changing;
355 int vfslocked;
356 int textset;
357 #ifdef MAC
358 struct label *interpvplabel = NULL;
359 int will_transition;
360 #endif
361 #ifdef HWPMC_HOOKS
362 struct pmckern_procexec pe;
363 #endif
364 static const char fexecv_proc_title[] = "(fexecv)";
365
366 vfslocked = 0;
367 imgp = &image_params;
368
369 /*
370 * Lock the process and set the P_INEXEC flag to indicate that
371 * it should be left alone until we're done here. This is
372 * necessary to avoid race conditions - e.g. in ptrace() -
373 * that might allow a local user to illicitly obtain elevated
374 * privileges.
375 */
376 PROC_LOCK(p);
377 KASSERT((p->p_flag & P_INEXEC) == 0,
378 ("%s(): process already has P_INEXEC flag", __func__));
379 p->p_flag |= P_INEXEC;
380 PROC_UNLOCK(p);
381
382 /*
383 * Initialize part of the common data
384 */
385 imgp->proc = p;
386 imgp->execlabel = NULL;
387 imgp->attr = &attr;
388 imgp->entry_addr = 0;
389 imgp->reloc_base = 0;
390 imgp->vmspace_destroyed = 0;
391 imgp->interpreted = 0;
392 imgp->opened = 0;
393 imgp->interpreter_name = NULL;
394 imgp->auxargs = NULL;
395 imgp->vp = NULL;
396 imgp->object = NULL;
397 imgp->firstpage = NULL;
398 imgp->ps_strings = 0;
399 imgp->auxarg_size = 0;
400 imgp->args = args;
401 imgp->execpath = imgp->freepath = NULL;
402 imgp->execpathp = 0;
403 imgp->canary = 0;
404 imgp->canarylen = 0;
405 imgp->pagesizes = 0;
406 imgp->pagesizeslen = 0;
407 imgp->stack_prot = 0;
408
409 #ifdef MAC
410 error = mac_execve_enter(imgp, mac_p);
411 if (error)
412 goto exec_fail;
413 #endif
414
415 imgp->image_header = NULL;
416
417 /*
418 * Translate the file name. namei() returns a vnode pointer
419 * in ni_vp amoung other things.
420 *
421 * XXXAUDIT: It would be desirable to also audit the name of the
422 * interpreter if this is an interpreted binary.
423 */
424 if (args->fname != NULL) {
425 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME
426 | MPSAFE | AUDITVNODE1, UIO_SYSSPACE, args->fname, td);
427 }
428
429 SDT_PROBE1(proc, kernel, , exec, args->fname);
430
431 interpret:
432 if (args->fname != NULL) {
433 #ifdef CAPABILITY_MODE
434 /*
435 * While capability mode can't reach this point via direct
436 * path arguments to execve(), we also don't allow
437 * interpreters to be used in capability mode (for now).
438 * Catch indirect lookups and return a permissions error.
439 */
440 if (IN_CAPABILITY_MODE(td)) {
441 error = ECAPMODE;
442 goto exec_fail;
443 }
444 #endif
445 error = namei(&nd);
446 if (error)
447 goto exec_fail;
448
449 vfslocked = NDHASGIANT(&nd);
450 binvp = nd.ni_vp;
451 imgp->vp = binvp;
452 } else {
453 AUDIT_ARG_FD(args->fd);
454 /*
455 * Some might argue that CAP_READ and/or CAP_MMAP should also
456 * be required here; such arguments will be entertained.
457 *
458 * Descriptors opened only with O_EXEC or O_RDONLY are allowed.
459 */
460 error = fgetvp_exec(td, args->fd, CAP_FEXECVE, &binvp);
461 if (error)
462 goto exec_fail;
463 vfslocked = VFS_LOCK_GIANT(binvp->v_mount);
464 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY);
465 AUDIT_ARG_VNODE1(binvp);
466 imgp->vp = binvp;
467 }
468
469 /*
470 * Check file permissions (also 'opens' file)
471 */
472 error = exec_check_permissions(imgp);
473 if (error)
474 goto exec_fail_dealloc;
475
476 imgp->object = imgp->vp->v_object;
477 if (imgp->object != NULL)
478 vm_object_reference(imgp->object);
479
480 /*
481 * Set VV_TEXT now so no one can write to the executable while we're
482 * activating it.
483 *
484 * Remember if this was set before and unset it in case this is not
485 * actually an executable image.
486 */
487 textset = VOP_IS_TEXT(imgp->vp);
488 VOP_SET_TEXT(imgp->vp);
489
490 error = exec_map_first_page(imgp);
491 if (error)
492 goto exec_fail_dealloc;
493
494 imgp->proc->p_osrel = 0;
495 /*
496 * If the current process has a special image activator it
497 * wants to try first, call it. For example, emulating shell
498 * scripts differently.
499 */
500 error = -1;
501 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL)
502 error = img_first(imgp);
503
504 /*
505 * Loop through the list of image activators, calling each one.
506 * An activator returns -1 if there is no match, 0 on success,
507 * and an error otherwise.
508 */
509 for (i = 0; error == -1 && execsw[i]; ++i) {
510 if (execsw[i]->ex_imgact == NULL ||
511 execsw[i]->ex_imgact == img_first) {
512 continue;
513 }
514 error = (*execsw[i]->ex_imgact)(imgp);
515 }
516
517 if (error) {
518 if (error == -1) {
519 if (textset == 0)
520 VOP_UNSET_TEXT(imgp->vp);
521 error = ENOEXEC;
522 }
523 goto exec_fail_dealloc;
524 }
525
526 /*
527 * Special interpreter operation, cleanup and loop up to try to
528 * activate the interpreter.
529 */
530 if (imgp->interpreted) {
531 exec_unmap_first_page(imgp);
532 /*
533 * VV_TEXT needs to be unset for scripts. There is a short
534 * period before we determine that something is a script where
535 * VV_TEXT will be set. The vnode lock is held over this
536 * entire period so nothing should illegitimately be blocked.
537 */
538 VOP_UNSET_TEXT(imgp->vp);
539 /* free name buffer and old vnode */
540 if (args->fname != NULL)
541 NDFREE(&nd, NDF_ONLY_PNBUF);
542 #ifdef MAC
543 mac_execve_interpreter_enter(binvp, &interpvplabel);
544 #endif
545 if (imgp->opened) {
546 VOP_CLOSE(binvp, FREAD, td->td_ucred, td);
547 imgp->opened = 0;
548 }
549 vput(binvp);
550 vm_object_deallocate(imgp->object);
551 imgp->object = NULL;
552 VFS_UNLOCK_GIANT(vfslocked);
553 vfslocked = 0;
554 /* set new name to that of the interpreter */
555 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME | MPSAFE,
556 UIO_SYSSPACE, imgp->interpreter_name, td);
557 args->fname = imgp->interpreter_name;
558 goto interpret;
559 }
560
561 /*
562 * NB: We unlock the vnode here because it is believed that none
563 * of the sv_copyout_strings/sv_fixup operations require the vnode.
564 */
565 VOP_UNLOCK(imgp->vp, 0);
566
567 /*
568 * Do the best to calculate the full path to the image file.
569 */
570 if (imgp->auxargs != NULL &&
571 ((args->fname != NULL && args->fname[0] == '/') ||
572 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0))
573 imgp->execpath = args->fname;
574
575 if (disallow_high_osrel &&
576 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) {
577 error = ENOEXEC;
578 uprintf("Osrel %d for image %s too high\n", p->p_osrel,
579 imgp->execpath != NULL ? imgp->execpath : "<unresolved>");
580 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
581 goto exec_fail_dealloc;
582 }
583
584 /*
585 * Copy out strings (args and env) and initialize stack base
586 */
587 if (p->p_sysent->sv_copyout_strings)
588 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp);
589 else
590 stack_base = exec_copyout_strings(imgp);
591
592 /*
593 * If custom stack fixup routine present for this process
594 * let it do the stack setup.
595 * Else stuff argument count as first item on stack
596 */
597 if (p->p_sysent->sv_fixup != NULL)
598 (*p->p_sysent->sv_fixup)(&stack_base, imgp);
599 else
600 suword(--stack_base, imgp->args->argc);
601
602 /*
603 * For security and other reasons, the file descriptor table cannot
604 * be shared after an exec.
605 */
606 fdunshare(p, td);
607
608 /*
609 * Malloc things before we need locks.
610 */
611 newcred = crget();
612 euip = uifind(attr.va_uid);
613 i = imgp->args->begin_envv - imgp->args->begin_argv;
614 /* Cache arguments if they fit inside our allowance */
615 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) {
616 newargs = pargs_alloc(i);
617 bcopy(imgp->args->begin_argv, newargs->ar_args, i);
618 }
619
620 /* close files on exec */
621 fdcloseexec(td);
622 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
623
624 /* Get a reference to the vnode prior to locking the proc */
625 VREF(binvp);
626
627 /*
628 * For security and other reasons, signal handlers cannot
629 * be shared after an exec. The new process gets a copy of the old
630 * handlers. In execsigs(), the new process will have its signals
631 * reset.
632 */
633 PROC_LOCK(p);
634 oldcred = crcopysafe(p, newcred);
635 if (sigacts_shared(p->p_sigacts)) {
636 oldsigacts = p->p_sigacts;
637 PROC_UNLOCK(p);
638 newsigacts = sigacts_alloc();
639 sigacts_copy(newsigacts, oldsigacts);
640 PROC_LOCK(p);
641 p->p_sigacts = newsigacts;
642 } else
643 oldsigacts = NULL;
644
645 /* Stop profiling */
646 stopprofclock(p);
647
648 /* reset caught signals */
649 execsigs(p);
650
651 /* name this process - nameiexec(p, ndp) */
652 bzero(p->p_comm, sizeof(p->p_comm));
653 if (args->fname)
654 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm,
655 min(nd.ni_cnd.cn_namelen, MAXCOMLEN));
656 else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0)
657 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title));
658 bcopy(p->p_comm, td->td_name, sizeof(td->td_name));
659 #ifdef KTR
660 sched_clear_tdname(td);
661 #endif
662
663 /*
664 * mark as execed, wakeup the process that vforked (if any) and tell
665 * it that it now has its own resources back
666 */
667 p->p_flag |= P_EXEC;
668 if (p->p_pptr && (p->p_flag & P_PPWAIT)) {
669 p->p_flag &= ~(P_PPWAIT | P_PPTRACE);
670 cv_broadcast(&p->p_pwait);
671 }
672
673 /*
674 * Implement image setuid/setgid.
675 *
676 * Don't honor setuid/setgid if the filesystem prohibits it or if
677 * the process is being traced.
678 *
679 * We disable setuid/setgid/etc in compatibility mode on the basis
680 * that most setugid applications are not written with that
681 * environment in mind, and will therefore almost certainly operate
682 * incorrectly. In principle there's no reason that setugid
683 * applications might not be useful in capability mode, so we may want
684 * to reconsider this conservative design choice in the future.
685 *
686 * XXXMAC: For the time being, use NOSUID to also prohibit
687 * transitions on the file system.
688 */
689 credential_changing = 0;
690 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid !=
691 attr.va_uid;
692 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid !=
693 attr.va_gid;
694 #ifdef MAC
695 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp,
696 interpvplabel, imgp);
697 credential_changing |= will_transition;
698 #endif
699
700 if (credential_changing &&
701 #ifdef CAPABILITY_MODE
702 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) &&
703 #endif
704 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 &&
705 (p->p_flag & P_TRACED) == 0) {
706 /*
707 * Turn off syscall tracing for set-id programs, except for
708 * root. Record any set-id flags first to make sure that
709 * we do not regain any tracing during a possible block.
710 */
711 setsugid(p);
712
713 #ifdef KTRACE
714 if (p->p_tracecred != NULL &&
715 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0))
716 ktrprocexec(p, &tracecred, &tracevp);
717 #endif
718 /*
719 * Close any file descriptors 0..2 that reference procfs,
720 * then make sure file descriptors 0..2 are in use.
721 *
722 * setugidsafety() may call closef() and then pfind()
723 * which may grab the process lock.
724 * fdcheckstd() may call falloc() which may block to
725 * allocate memory, so temporarily drop the process lock.
726 */
727 PROC_UNLOCK(p);
728 VOP_UNLOCK(imgp->vp, 0);
729 setugidsafety(td);
730 error = fdcheckstd(td);
731 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
732 if (error != 0)
733 goto done1;
734 PROC_LOCK(p);
735 /*
736 * Set the new credentials.
737 */
738 if (attr.va_mode & S_ISUID)
739 change_euid(newcred, euip);
740 if (attr.va_mode & S_ISGID)
741 change_egid(newcred, attr.va_gid);
742 #ifdef MAC
743 if (will_transition) {
744 mac_vnode_execve_transition(oldcred, newcred, imgp->vp,
745 interpvplabel, imgp);
746 }
747 #endif
748 /*
749 * Implement correct POSIX saved-id behavior.
750 *
751 * XXXMAC: Note that the current logic will save the
752 * uid and gid if a MAC domain transition occurs, even
753 * though maybe it shouldn't.
754 */
755 change_svuid(newcred, newcred->cr_uid);
756 change_svgid(newcred, newcred->cr_gid);
757 p->p_ucred = newcred;
758 newcred = NULL;
759 } else {
760 if (oldcred->cr_uid == oldcred->cr_ruid &&
761 oldcred->cr_gid == oldcred->cr_rgid)
762 p->p_flag &= ~P_SUGID;
763 /*
764 * Implement correct POSIX saved-id behavior.
765 *
766 * XXX: It's not clear that the existing behavior is
767 * POSIX-compliant. A number of sources indicate that the
768 * saved uid/gid should only be updated if the new ruid is
769 * not equal to the old ruid, or the new euid is not equal
770 * to the old euid and the new euid is not equal to the old
771 * ruid. The FreeBSD code always updates the saved uid/gid.
772 * Also, this code uses the new (replaced) euid and egid as
773 * the source, which may or may not be the right ones to use.
774 */
775 if (oldcred->cr_svuid != oldcred->cr_uid ||
776 oldcred->cr_svgid != oldcred->cr_gid) {
777 change_svuid(newcred, newcred->cr_uid);
778 change_svgid(newcred, newcred->cr_gid);
779 p->p_ucred = newcred;
780 newcred = NULL;
781 }
782 }
783
784 /*
785 * Store the vp for use in procfs. This vnode was referenced prior
786 * to locking the proc lock.
787 */
788 textvp = p->p_textvp;
789 p->p_textvp = binvp;
790
791 #ifdef KDTRACE_HOOKS
792 /*
793 * Tell the DTrace fasttrap provider about the exec if it
794 * has declared an interest.
795 */
796 if (dtrace_fasttrap_exec)
797 dtrace_fasttrap_exec(p);
798 #endif
799
800 /*
801 * Notify others that we exec'd, and clear the P_INEXEC flag
802 * as we're now a bona fide freshly-execed process.
803 */
804 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC);
805 p->p_flag &= ~P_INEXEC;
806
807 /* clear "fork but no exec" flag, as we _are_ execing */
808 p->p_acflag &= ~AFORK;
809
810 /*
811 * Free any previous argument cache and replace it with
812 * the new argument cache, if any.
813 */
814 oldargs = p->p_args;
815 p->p_args = newargs;
816 newargs = NULL;
817
818 #ifdef HWPMC_HOOKS
819 /*
820 * Check if system-wide sampling is in effect or if the
821 * current process is using PMCs. If so, do exec() time
822 * processing. This processing needs to happen AFTER the
823 * P_INEXEC flag is cleared.
824 *
825 * The proc lock needs to be released before taking the PMC
826 * SX.
827 */
828 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) {
829 PROC_UNLOCK(p);
830 VOP_UNLOCK(imgp->vp, 0);
831 pe.pm_credentialschanged = credential_changing;
832 pe.pm_entryaddr = imgp->entry_addr;
833
834 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe);
835 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
836 } else
837 PROC_UNLOCK(p);
838 #else /* !HWPMC_HOOKS */
839 PROC_UNLOCK(p);
840 #endif
841
842 /* Set values passed into the program in registers. */
843 if (p->p_sysent->sv_setregs)
844 (*p->p_sysent->sv_setregs)(td, imgp,
845 (u_long)(uintptr_t)stack_base);
846 else
847 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base);
848
849 vfs_mark_atime(imgp->vp, td->td_ucred);
850
851 SDT_PROBE1(proc, kernel, , exec__success, args->fname);
852
853 done1:
854 /*
855 * Free any resources malloc'd earlier that we didn't use.
856 */
857 uifree(euip);
858 if (newcred == NULL)
859 crfree(oldcred);
860 else
861 crfree(newcred);
862 VOP_UNLOCK(imgp->vp, 0);
863
864 /*
865 * Handle deferred decrement of ref counts.
866 */
867 if (textvp != NULL) {
868 int tvfslocked;
869
870 tvfslocked = VFS_LOCK_GIANT(textvp->v_mount);
871 vrele(textvp);
872 VFS_UNLOCK_GIANT(tvfslocked);
873 }
874 if (binvp && error != 0)
875 vrele(binvp);
876 #ifdef KTRACE
877 if (tracevp != NULL) {
878 int tvfslocked;
879
880 tvfslocked = VFS_LOCK_GIANT(tracevp->v_mount);
881 vrele(tracevp);
882 VFS_UNLOCK_GIANT(tvfslocked);
883 }
884 if (tracecred != NULL)
885 crfree(tracecred);
886 #endif
887 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
888 pargs_drop(oldargs);
889 pargs_drop(newargs);
890 if (oldsigacts != NULL)
891 sigacts_free(oldsigacts);
892
893 exec_fail_dealloc:
894
895 /*
896 * free various allocated resources
897 */
898 if (imgp->firstpage != NULL)
899 exec_unmap_first_page(imgp);
900
901 if (imgp->vp != NULL) {
902 if (args->fname)
903 NDFREE(&nd, NDF_ONLY_PNBUF);
904 if (imgp->opened)
905 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td);
906 vput(imgp->vp);
907 }
908
909 if (imgp->object != NULL)
910 vm_object_deallocate(imgp->object);
911
912 free(imgp->freepath, M_TEMP);
913
914 if (error == 0) {
915 PROC_LOCK(p);
916 td->td_dbgflags |= TDB_EXEC;
917 PROC_UNLOCK(p);
918
919 /*
920 * Stop the process here if its stop event mask has
921 * the S_EXEC bit set.
922 */
923 STOPEVENT(p, S_EXEC, 0);
924 goto done2;
925 }
926
927 exec_fail:
928 /* we're done here, clear P_INEXEC */
929 PROC_LOCK(p);
930 p->p_flag &= ~P_INEXEC;
931 PROC_UNLOCK(p);
932
933 SDT_PROBE1(proc, kernel, , exec__failure, error);
934
935 done2:
936 #ifdef MAC
937 mac_execve_exit(imgp);
938 mac_execve_interpreter_exit(interpvplabel);
939 #endif
940 VFS_UNLOCK_GIANT(vfslocked);
941 exec_free_args(args);
942
943 if (error && imgp->vmspace_destroyed) {
944 /* sorry, no more process anymore. exit gracefully */
945 exit1(td, W_EXITCODE(0, SIGABRT));
946 /* NOT REACHED */
947 }
948
949 #ifdef KTRACE
950 if (error == 0)
951 ktrprocctor(p);
952 #endif
953
954 return (error);
955 }
956
957 int
exec_map_first_page(imgp)958 exec_map_first_page(imgp)
959 struct image_params *imgp;
960 {
961 int rv, i;
962 int initial_pagein;
963 vm_page_t ma[VM_INITIAL_PAGEIN];
964 vm_object_t object;
965
966 if (imgp->firstpage != NULL)
967 exec_unmap_first_page(imgp);
968
969 object = imgp->vp->v_object;
970 if (object == NULL)
971 return (EACCES);
972 VM_OBJECT_LOCK(object);
973 #if VM_NRESERVLEVEL > 0
974 if ((object->flags & OBJ_COLORED) == 0) {
975 object->flags |= OBJ_COLORED;
976 object->pg_color = 0;
977 }
978 #endif
979 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
980 if (ma[0]->valid != VM_PAGE_BITS_ALL) {
981 initial_pagein = VM_INITIAL_PAGEIN;
982 if (initial_pagein > object->size)
983 initial_pagein = object->size;
984 for (i = 1; i < initial_pagein; i++) {
985 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) {
986 if (ma[i]->valid)
987 break;
988 if ((ma[i]->oflags & VPO_BUSY) || ma[i]->busy)
989 break;
990 vm_page_busy(ma[i]);
991 } else {
992 ma[i] = vm_page_alloc(object, i,
993 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED);
994 if (ma[i] == NULL)
995 break;
996 }
997 }
998 initial_pagein = i;
999 rv = vm_pager_get_pages(object, ma, initial_pagein, 0);
1000 ma[0] = vm_page_lookup(object, 0);
1001 if ((rv != VM_PAGER_OK) || (ma[0] == NULL)) {
1002 if (ma[0] != NULL) {
1003 vm_page_lock(ma[0]);
1004 vm_page_free(ma[0]);
1005 vm_page_unlock(ma[0]);
1006 }
1007 VM_OBJECT_UNLOCK(object);
1008 return (EIO);
1009 }
1010 }
1011 vm_page_lock(ma[0]);
1012 vm_page_hold(ma[0]);
1013 vm_page_unlock(ma[0]);
1014 vm_page_wakeup(ma[0]);
1015 VM_OBJECT_UNLOCK(object);
1016
1017 imgp->firstpage = sf_buf_alloc(ma[0], 0);
1018 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage);
1019
1020 return (0);
1021 }
1022
1023 void
exec_unmap_first_page(imgp)1024 exec_unmap_first_page(imgp)
1025 struct image_params *imgp;
1026 {
1027 vm_page_t m;
1028
1029 if (imgp->firstpage != NULL) {
1030 m = sf_buf_page(imgp->firstpage);
1031 sf_buf_free(imgp->firstpage);
1032 imgp->firstpage = NULL;
1033 vm_page_lock(m);
1034 vm_page_unhold(m);
1035 vm_page_unlock(m);
1036 }
1037 }
1038
1039 /*
1040 * Destroy old address space, and allocate a new stack
1041 * The new stack is only SGROWSIZ large because it is grown
1042 * automatically in trap.c.
1043 */
1044 int
exec_new_vmspace(imgp,sv)1045 exec_new_vmspace(imgp, sv)
1046 struct image_params *imgp;
1047 struct sysentvec *sv;
1048 {
1049 int error;
1050 struct proc *p = imgp->proc;
1051 struct vmspace *vmspace = p->p_vmspace;
1052 vm_object_t obj;
1053 vm_offset_t sv_minuser, stack_addr;
1054 vm_map_t map;
1055 u_long ssiz;
1056
1057 imgp->vmspace_destroyed = 1;
1058 imgp->sysent = sv;
1059
1060 /* May be called with Giant held */
1061 EVENTHANDLER_INVOKE(process_exec, p, imgp);
1062
1063 /*
1064 * Blow away entire process VM, if address space not shared,
1065 * otherwise, create a new VM space so that other threads are
1066 * not disrupted
1067 */
1068 map = &vmspace->vm_map;
1069 if (map_at_zero)
1070 sv_minuser = sv->sv_minuser;
1071 else
1072 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE);
1073 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser &&
1074 vm_map_max(map) == sv->sv_maxuser) {
1075 shmexit(vmspace);
1076 pmap_remove_pages(vmspace_pmap(vmspace));
1077 vm_map_remove(map, vm_map_min(map), vm_map_max(map));
1078 } else {
1079 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser);
1080 if (error)
1081 return (error);
1082 vmspace = p->p_vmspace;
1083 map = &vmspace->vm_map;
1084 }
1085
1086 /* Map a shared page */
1087 obj = sv->sv_shared_page_obj;
1088 if (obj != NULL) {
1089 vm_object_reference(obj);
1090 error = vm_map_fixed(map, obj, 0,
1091 sv->sv_shared_page_base, sv->sv_shared_page_len,
1092 VM_PROT_READ | VM_PROT_EXECUTE,
1093 VM_PROT_READ | VM_PROT_EXECUTE,
1094 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE);
1095 if (error) {
1096 vm_object_deallocate(obj);
1097 return (error);
1098 }
1099 }
1100
1101 /* Allocate a new stack */
1102 if (sv->sv_maxssiz != NULL)
1103 ssiz = *sv->sv_maxssiz;
1104 else
1105 ssiz = maxssiz;
1106 stack_addr = sv->sv_usrstack - ssiz;
1107 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz,
1108 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot :
1109 sv->sv_stackprot,
1110 VM_PROT_ALL, MAP_STACK_GROWS_DOWN);
1111 if (error)
1112 return (error);
1113
1114 #ifdef __ia64__
1115 /* Allocate a new register stack */
1116 stack_addr = IA64_BACKINGSTORE;
1117 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz,
1118 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP);
1119 if (error)
1120 return (error);
1121 #endif
1122
1123 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the
1124 * VM_STACK case, but they are still used to monitor the size of the
1125 * process stack so we can check the stack rlimit.
1126 */
1127 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT;
1128 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz;
1129
1130 return (0);
1131 }
1132
1133 /*
1134 * Copy out argument and environment strings from the old process address
1135 * space into the temporary string buffer.
1136 */
1137 int
exec_copyin_args(struct image_args * args,char * fname,enum uio_seg segflg,char ** argv,char ** envv)1138 exec_copyin_args(struct image_args *args, char *fname,
1139 enum uio_seg segflg, char **argv, char **envv)
1140 {
1141 char *argp, *envp;
1142 int error;
1143 size_t length;
1144
1145 bzero(args, sizeof(*args));
1146 if (argv == NULL)
1147 return (EFAULT);
1148
1149 /*
1150 * Allocate demand-paged memory for the file name, argument, and
1151 * environment strings.
1152 */
1153 error = exec_alloc_args(args);
1154 if (error != 0)
1155 return (error);
1156
1157 /*
1158 * Copy the file name.
1159 */
1160 if (fname != NULL) {
1161 args->fname = args->buf;
1162 error = (segflg == UIO_SYSSPACE) ?
1163 copystr(fname, args->fname, PATH_MAX, &length) :
1164 copyinstr(fname, args->fname, PATH_MAX, &length);
1165 if (error != 0)
1166 goto err_exit;
1167 } else
1168 length = 0;
1169
1170 args->begin_argv = args->buf + length;
1171 args->endp = args->begin_argv;
1172 args->stringspace = ARG_MAX;
1173
1174 /*
1175 * extract arguments first
1176 */
1177 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) {
1178 if (argp == (caddr_t) -1) {
1179 error = EFAULT;
1180 goto err_exit;
1181 }
1182 if ((error = copyinstr(argp, args->endp,
1183 args->stringspace, &length))) {
1184 if (error == ENAMETOOLONG)
1185 error = E2BIG;
1186 goto err_exit;
1187 }
1188 args->stringspace -= length;
1189 args->endp += length;
1190 args->argc++;
1191 }
1192
1193 args->begin_envv = args->endp;
1194
1195 /*
1196 * extract environment strings
1197 */
1198 if (envv) {
1199 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) {
1200 if (envp == (caddr_t)-1) {
1201 error = EFAULT;
1202 goto err_exit;
1203 }
1204 if ((error = copyinstr(envp, args->endp,
1205 args->stringspace, &length))) {
1206 if (error == ENAMETOOLONG)
1207 error = E2BIG;
1208 goto err_exit;
1209 }
1210 args->stringspace -= length;
1211 args->endp += length;
1212 args->envc++;
1213 }
1214 }
1215
1216 return (0);
1217
1218 err_exit:
1219 exec_free_args(args);
1220 return (error);
1221 }
1222
1223 /*
1224 * Allocate temporary demand-paged, zero-filled memory for the file name,
1225 * argument, and environment strings. Returns zero if the allocation succeeds
1226 * and ENOMEM otherwise.
1227 */
1228 int
exec_alloc_args(struct image_args * args)1229 exec_alloc_args(struct image_args *args)
1230 {
1231
1232 args->buf = (char *)kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX);
1233 return (args->buf != NULL ? 0 : ENOMEM);
1234 }
1235
1236 void
exec_free_args(struct image_args * args)1237 exec_free_args(struct image_args *args)
1238 {
1239
1240 if (args->buf != NULL) {
1241 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf,
1242 PATH_MAX + ARG_MAX);
1243 args->buf = NULL;
1244 }
1245 if (args->fname_buf != NULL) {
1246 free(args->fname_buf, M_TEMP);
1247 args->fname_buf = NULL;
1248 }
1249 }
1250
1251 /*
1252 * Copy strings out to the new process address space, constructing new arg
1253 * and env vector tables. Return a pointer to the base so that it can be used
1254 * as the initial stack pointer.
1255 */
1256 register_t *
exec_copyout_strings(imgp)1257 exec_copyout_strings(imgp)
1258 struct image_params *imgp;
1259 {
1260 int argc, envc;
1261 char **vectp;
1262 char *stringp;
1263 uintptr_t destp;
1264 register_t *stack_base;
1265 struct ps_strings *arginfo;
1266 struct proc *p;
1267 size_t execpath_len;
1268 int szsigcode, szps;
1269 char canary[sizeof(long) * 8];
1270
1271 szps = sizeof(pagesizes[0]) * MAXPAGESIZES;
1272 /*
1273 * Calculate string base and vector table pointers.
1274 * Also deal with signal trampoline code for this exec type.
1275 */
1276 if (imgp->execpath != NULL && imgp->auxargs != NULL)
1277 execpath_len = strlen(imgp->execpath) + 1;
1278 else
1279 execpath_len = 0;
1280 p = imgp->proc;
1281 szsigcode = 0;
1282 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings;
1283 if (p->p_sysent->sv_sigcode_base == 0) {
1284 if (p->p_sysent->sv_szsigcode != NULL)
1285 szsigcode = *(p->p_sysent->sv_szsigcode);
1286 }
1287 destp = (uintptr_t)arginfo;
1288
1289 /*
1290 * install sigcode
1291 */
1292 if (szsigcode != 0) {
1293 destp -= szsigcode;
1294 destp = rounddown2(destp, sizeof(void *));
1295 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode);
1296 }
1297
1298 /*
1299 * Copy the image path for the rtld.
1300 */
1301 if (execpath_len != 0) {
1302 destp -= execpath_len;
1303 imgp->execpathp = destp;
1304 copyout(imgp->execpath, (void *)destp, execpath_len);
1305 }
1306
1307 /*
1308 * Prepare the canary for SSP.
1309 */
1310 arc4rand(canary, sizeof(canary), 0);
1311 destp -= sizeof(canary);
1312 imgp->canary = destp;
1313 copyout(canary, (void *)destp, sizeof(canary));
1314 imgp->canarylen = sizeof(canary);
1315
1316 /*
1317 * Prepare the pagesizes array.
1318 */
1319 destp -= szps;
1320 destp = rounddown2(destp, sizeof(void *));
1321 imgp->pagesizes = destp;
1322 copyout(pagesizes, (void *)destp, szps);
1323 imgp->pagesizeslen = szps;
1324
1325 destp -= ARG_MAX - imgp->args->stringspace;
1326 destp = rounddown2(destp, sizeof(void *));
1327
1328 /*
1329 * If we have a valid auxargs ptr, prepare some room
1330 * on the stack.
1331 */
1332 if (imgp->auxargs) {
1333 /*
1334 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for
1335 * lower compatibility.
1336 */
1337 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size :
1338 (AT_COUNT * 2);
1339 /*
1340 * The '+ 2' is for the null pointers at the end of each of
1341 * the arg and env vector sets,and imgp->auxarg_size is room
1342 * for argument of Runtime loader.
1343 */
1344 vectp = (char **)(destp - (imgp->args->argc +
1345 imgp->args->envc + 2 + imgp->auxarg_size)
1346 * sizeof(char *));
1347 } else {
1348 /*
1349 * The '+ 2' is for the null pointers at the end of each of
1350 * the arg and env vector sets
1351 */
1352 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc
1353 + 2) * sizeof(char *));
1354 }
1355
1356 /*
1357 * vectp also becomes our initial stack base
1358 */
1359 stack_base = (register_t *)vectp;
1360
1361 stringp = imgp->args->begin_argv;
1362 argc = imgp->args->argc;
1363 envc = imgp->args->envc;
1364
1365 /*
1366 * Copy out strings - arguments and environment.
1367 */
1368 copyout(stringp, (void *)destp, ARG_MAX - imgp->args->stringspace);
1369
1370 /*
1371 * Fill in "ps_strings" struct for ps, w, etc.
1372 */
1373 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp);
1374 suword32(&arginfo->ps_nargvstr, argc);
1375
1376 /*
1377 * Fill in argument portion of vector table.
1378 */
1379 for (; argc > 0; --argc) {
1380 suword(vectp++, (long)(intptr_t)destp);
1381 while (*stringp++ != 0)
1382 destp++;
1383 destp++;
1384 }
1385
1386 /* a null vector table pointer separates the argp's from the envp's */
1387 suword(vectp++, 0);
1388
1389 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp);
1390 suword32(&arginfo->ps_nenvstr, envc);
1391
1392 /*
1393 * Fill in environment portion of vector table.
1394 */
1395 for (; envc > 0; --envc) {
1396 suword(vectp++, (long)(intptr_t)destp);
1397 while (*stringp++ != 0)
1398 destp++;
1399 destp++;
1400 }
1401
1402 /* end of vector table is a null pointer */
1403 suword(vectp, 0);
1404
1405 return (stack_base);
1406 }
1407
1408 /*
1409 * Check permissions of file to execute.
1410 * Called with imgp->vp locked.
1411 * Return 0 for success or error code on failure.
1412 */
1413 int
exec_check_permissions(imgp)1414 exec_check_permissions(imgp)
1415 struct image_params *imgp;
1416 {
1417 struct vnode *vp = imgp->vp;
1418 struct vattr *attr = imgp->attr;
1419 struct thread *td;
1420 int error, writecount;
1421
1422 td = curthread;
1423
1424 /* Get file attributes */
1425 error = VOP_GETATTR(vp, attr, td->td_ucred);
1426 if (error)
1427 return (error);
1428
1429 #ifdef MAC
1430 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp);
1431 if (error)
1432 return (error);
1433 #endif
1434
1435 /*
1436 * 1) Check if file execution is disabled for the filesystem that
1437 * this file resides on.
1438 * 2) Ensure that at least one execute bit is on. Otherwise, a
1439 * privileged user will always succeed, and we don't want this
1440 * to happen unless the file really is executable.
1441 * 3) Ensure that the file is a regular file.
1442 */
1443 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) ||
1444 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 ||
1445 (attr->va_type != VREG))
1446 return (EACCES);
1447
1448 /*
1449 * Zero length files can't be exec'd
1450 */
1451 if (attr->va_size == 0)
1452 return (ENOEXEC);
1453
1454 /*
1455 * Check for execute permission to file based on current credentials.
1456 */
1457 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td);
1458 if (error)
1459 return (error);
1460
1461 /*
1462 * Check number of open-for-writes on the file and deny execution
1463 * if there are any.
1464 */
1465 error = VOP_GET_WRITECOUNT(vp, &writecount);
1466 if (error != 0)
1467 return (error);
1468 if (writecount != 0)
1469 return (ETXTBSY);
1470
1471 /*
1472 * Call filesystem specific open routine (which does nothing in the
1473 * general case).
1474 */
1475 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL);
1476 if (error == 0)
1477 imgp->opened = 1;
1478 return (error);
1479 }
1480
1481 /*
1482 * Exec handler registration
1483 */
1484 int
exec_register(execsw_arg)1485 exec_register(execsw_arg)
1486 const struct execsw *execsw_arg;
1487 {
1488 const struct execsw **es, **xs, **newexecsw;
1489 int count = 2; /* New slot and trailing NULL */
1490
1491 if (execsw)
1492 for (es = execsw; *es; es++)
1493 count++;
1494 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
1495 if (newexecsw == NULL)
1496 return (ENOMEM);
1497 xs = newexecsw;
1498 if (execsw)
1499 for (es = execsw; *es; es++)
1500 *xs++ = *es;
1501 *xs++ = execsw_arg;
1502 *xs = NULL;
1503 if (execsw)
1504 free(execsw, M_TEMP);
1505 execsw = newexecsw;
1506 return (0);
1507 }
1508
1509 int
exec_unregister(execsw_arg)1510 exec_unregister(execsw_arg)
1511 const struct execsw *execsw_arg;
1512 {
1513 const struct execsw **es, **xs, **newexecsw;
1514 int count = 1;
1515
1516 if (execsw == NULL)
1517 panic("unregister with no handlers left?\n");
1518
1519 for (es = execsw; *es; es++) {
1520 if (*es == execsw_arg)
1521 break;
1522 }
1523 if (*es == NULL)
1524 return (ENOENT);
1525 for (es = execsw; *es; es++)
1526 if (*es != execsw_arg)
1527 count++;
1528 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
1529 if (newexecsw == NULL)
1530 return (ENOMEM);
1531 xs = newexecsw;
1532 for (es = execsw; *es; es++)
1533 if (*es != execsw_arg)
1534 *xs++ = *es;
1535 *xs = NULL;
1536 if (execsw)
1537 free(execsw, M_TEMP);
1538 execsw = newexecsw;
1539 return (0);
1540 }
1541