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/10/sys/kern/kern_exec.c 330067 2018-02-27 14:45:55Z 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/capsicum.h>
38 #include <sys/systm.h>
39 #include <sys/capsicum.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/ptrace.h>
59 #include <sys/namei.h>
60 #include <sys/resourcevar.h>
61 #include <sys/rwlock.h>
62 #include <sys/sched.h>
63 #include <sys/sdt.h>
64 #include <sys/sf_buf.h>
65 #include <sys/syscallsubr.h>
66 #include <sys/sysent.h>
67 #include <sys/shm.h>
68 #include <sys/sysctl.h>
69 #include <sys/vnode.h>
70 #include <sys/stat.h>
71 #ifdef KTRACE
72 #include <sys/ktrace.h>
73 #endif
74
75 #include <vm/vm.h>
76 #include <vm/vm_param.h>
77 #include <vm/pmap.h>
78 #include <vm/vm_page.h>
79 #include <vm/vm_map.h>
80 #include <vm/vm_kern.h>
81 #include <vm/vm_extern.h>
82 #include <vm/vm_object.h>
83 #include <vm/vm_pager.h>
84
85 #ifdef HWPMC_HOOKS
86 #include <sys/pmckern.h>
87 #endif
88
89 #include <machine/reg.h>
90
91 #include <security/audit/audit.h>
92 #include <security/mac/mac_framework.h>
93
94 #ifdef KDTRACE_HOOKS
95 #include <sys/dtrace_bsd.h>
96 dtrace_execexit_func_t dtrace_fasttrap_exec;
97 #endif
98
99 SDT_PROVIDER_DECLARE(proc);
100 SDT_PROBE_DEFINE1(proc, , , exec, "char *");
101 SDT_PROBE_DEFINE1(proc, , , exec__failure, "int");
102 SDT_PROBE_DEFINE1(proc, , , exec__success, "char *");
103
104 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments");
105
106 int coredump_pack_fileinfo = 1;
107 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_fileinfo, CTLFLAG_RWTUN,
108 &coredump_pack_fileinfo, 0,
109 "Enable file path packing in 'procstat -f' coredump notes");
110
111 int coredump_pack_vmmapinfo = 1;
112 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_vmmapinfo, CTLFLAG_RWTUN,
113 &coredump_pack_vmmapinfo, 0,
114 "Enable file path packing in 'procstat -v' coredump notes");
115
116 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS);
117 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS);
118 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS);
119 static int do_execve(struct thread *td, struct image_args *args,
120 struct mac *mac_p);
121
122 /* XXX This should be vm_size_t. */
123 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD,
124 NULL, 0, sysctl_kern_ps_strings, "LU", "");
125
126 /* XXX This should be vm_size_t. */
127 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD|
128 CTLFLAG_CAPRD, NULL, 0, sysctl_kern_usrstack, "LU", "");
129
130 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD,
131 NULL, 0, sysctl_kern_stackprot, "I", "");
132
133 u_long ps_arg_cache_limit = PAGE_SIZE / 16;
134 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW,
135 &ps_arg_cache_limit, 0, "");
136
137 static int disallow_high_osrel;
138 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW,
139 &disallow_high_osrel, 0,
140 "Disallow execution of binaries built for higher version of the world");
141
142 static int map_at_zero = 0;
143 TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero);
144 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &map_at_zero, 0,
145 "Permit processes to map an object at virtual address 0.");
146
147 static int
sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)148 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)
149 {
150 struct proc *p;
151 int error;
152
153 p = curproc;
154 #ifdef SCTL_MASK32
155 if (req->flags & SCTL_MASK32) {
156 unsigned int val;
157 val = (unsigned int)p->p_sysent->sv_psstrings;
158 error = SYSCTL_OUT(req, &val, sizeof(val));
159 } else
160 #endif
161 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings,
162 sizeof(p->p_sysent->sv_psstrings));
163 return error;
164 }
165
166 static int
sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)167 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)
168 {
169 struct proc *p;
170 int error;
171
172 p = curproc;
173 #ifdef SCTL_MASK32
174 if (req->flags & SCTL_MASK32) {
175 unsigned int val;
176 val = (unsigned int)p->p_sysent->sv_usrstack;
177 error = SYSCTL_OUT(req, &val, sizeof(val));
178 } else
179 #endif
180 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack,
181 sizeof(p->p_sysent->sv_usrstack));
182 return error;
183 }
184
185 static int
sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS)186 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS)
187 {
188 struct proc *p;
189
190 p = curproc;
191 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot,
192 sizeof(p->p_sysent->sv_stackprot)));
193 }
194
195 /*
196 * Each of the items is a pointer to a `const struct execsw', hence the
197 * double pointer here.
198 */
199 static const struct execsw **execsw;
200
201 #ifndef _SYS_SYSPROTO_H_
202 struct execve_args {
203 char *fname;
204 char **argv;
205 char **envv;
206 };
207 #endif
208
209 int
sys_execve(struct thread * td,struct execve_args * uap)210 sys_execve(struct thread *td, struct execve_args *uap)
211 {
212 struct image_args args;
213 struct vmspace *oldvmspace;
214 int error;
215
216 error = pre_execve(td, &oldvmspace);
217 if (error != 0)
218 return (error);
219 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
220 uap->argv, uap->envv);
221 if (error == 0)
222 error = kern_execve(td, &args, NULL);
223 post_execve(td, error, oldvmspace);
224 return (error);
225 }
226
227 #ifndef _SYS_SYSPROTO_H_
228 struct fexecve_args {
229 int fd;
230 char **argv;
231 char **envv;
232 }
233 #endif
234 int
sys_fexecve(struct thread * td,struct fexecve_args * uap)235 sys_fexecve(struct thread *td, struct fexecve_args *uap)
236 {
237 struct image_args args;
238 struct vmspace *oldvmspace;
239 int error;
240
241 error = pre_execve(td, &oldvmspace);
242 if (error != 0)
243 return (error);
244 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE,
245 uap->argv, uap->envv);
246 if (error == 0) {
247 args.fd = uap->fd;
248 error = kern_execve(td, &args, NULL);
249 }
250 post_execve(td, error, oldvmspace);
251 return (error);
252 }
253
254 #ifndef _SYS_SYSPROTO_H_
255 struct __mac_execve_args {
256 char *fname;
257 char **argv;
258 char **envv;
259 struct mac *mac_p;
260 };
261 #endif
262
263 int
sys___mac_execve(struct thread * td,struct __mac_execve_args * uap)264 sys___mac_execve(struct thread *td, struct __mac_execve_args *uap)
265 {
266 #ifdef MAC
267 struct image_args args;
268 struct vmspace *oldvmspace;
269 int error;
270
271 error = pre_execve(td, &oldvmspace);
272 if (error != 0)
273 return (error);
274 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
275 uap->argv, uap->envv);
276 if (error == 0)
277 error = kern_execve(td, &args, uap->mac_p);
278 post_execve(td, error, oldvmspace);
279 return (error);
280 #else
281 return (ENOSYS);
282 #endif
283 }
284
285 int
pre_execve(struct thread * td,struct vmspace ** oldvmspace)286 pre_execve(struct thread *td, struct vmspace **oldvmspace)
287 {
288 struct proc *p;
289 int error;
290
291 KASSERT(td == curthread, ("non-current thread %p", td));
292 error = 0;
293 p = td->td_proc;
294 if ((p->p_flag & P_HADTHREADS) != 0) {
295 PROC_LOCK(p);
296 if (thread_single(p, SINGLE_BOUNDARY) != 0)
297 error = ERESTART;
298 PROC_UNLOCK(p);
299 }
300 KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0,
301 ("nested execve"));
302 *oldvmspace = p->p_vmspace;
303 return (error);
304 }
305
306 void
post_execve(struct thread * td,int error,struct vmspace * oldvmspace)307 post_execve(struct thread *td, int error, struct vmspace *oldvmspace)
308 {
309 struct proc *p;
310
311 KASSERT(td == curthread, ("non-current thread %p", td));
312 p = td->td_proc;
313 if ((p->p_flag & P_HADTHREADS) != 0) {
314 PROC_LOCK(p);
315 /*
316 * If success, we upgrade to SINGLE_EXIT state to
317 * force other threads to suicide.
318 */
319 if (error == 0)
320 thread_single(p, SINGLE_EXIT);
321 else
322 thread_single_end(p, SINGLE_BOUNDARY);
323 PROC_UNLOCK(p);
324 }
325 if ((td->td_pflags & TDP_EXECVMSPC) != 0) {
326 KASSERT(p->p_vmspace != oldvmspace,
327 ("oldvmspace still used"));
328 vmspace_free(oldvmspace);
329 td->td_pflags &= ~TDP_EXECVMSPC;
330 }
331 }
332
333 /*
334 * XXX: kern_execve has the astonishing property of not always returning to
335 * the caller. If sufficiently bad things happen during the call to
336 * do_execve(), it can end up calling exit1(); as a result, callers must
337 * avoid doing anything which they might need to undo (e.g., allocating
338 * memory).
339 */
340 int
kern_execve(struct thread * td,struct image_args * args,struct mac * mac_p)341 kern_execve(struct thread *td, struct image_args *args, struct mac *mac_p)
342 {
343
344 AUDIT_ARG_ARGV(args->begin_argv, args->argc,
345 args->begin_envv - args->begin_argv);
346 AUDIT_ARG_ENVV(args->begin_envv, args->envc,
347 args->endp - args->begin_envv);
348 return (do_execve(td, args, mac_p));
349 }
350
351 /*
352 * In-kernel implementation of execve(). All arguments are assumed to be
353 * userspace pointers from the passed thread.
354 */
355 static int
do_execve(td,args,mac_p)356 do_execve(td, args, mac_p)
357 struct thread *td;
358 struct image_args *args;
359 struct mac *mac_p;
360 {
361 struct proc *p = td->td_proc;
362 struct nameidata nd;
363 struct ucred *oldcred;
364 struct uidinfo *euip = NULL;
365 register_t *stack_base;
366 int error, i;
367 struct image_params image_params, *imgp;
368 struct vattr attr;
369 int (*img_first)(struct image_params *);
370 struct pargs *oldargs = NULL, *newargs = NULL;
371 struct sigacts *oldsigacts = NULL, *newsigacts = NULL;
372 #ifdef KTRACE
373 struct vnode *tracevp = NULL;
374 struct ucred *tracecred = NULL;
375 #endif
376 struct vnode *oldtextvp = NULL, *newtextvp;
377 cap_rights_t rights;
378 int credential_changing;
379 int textset;
380 #ifdef MAC
381 struct label *interpvplabel = NULL;
382 int will_transition;
383 #endif
384 #ifdef HWPMC_HOOKS
385 struct pmckern_procexec pe;
386 #endif
387 static const char fexecv_proc_title[] = "(fexecv)";
388
389 imgp = &image_params;
390
391 /*
392 * Lock the process and set the P_INEXEC flag to indicate that
393 * it should be left alone until we're done here. This is
394 * necessary to avoid race conditions - e.g. in ptrace() -
395 * that might allow a local user to illicitly obtain elevated
396 * privileges.
397 */
398 PROC_LOCK(p);
399 KASSERT((p->p_flag & P_INEXEC) == 0,
400 ("%s(): process already has P_INEXEC flag", __func__));
401 p->p_flag |= P_INEXEC;
402 PROC_UNLOCK(p);
403
404 /*
405 * Initialize part of the common data
406 */
407 bzero(imgp, sizeof(*imgp));
408 imgp->proc = p;
409 imgp->attr = &attr;
410 imgp->args = args;
411 oldcred = p->p_ucred;
412
413 #ifdef MAC
414 error = mac_execve_enter(imgp, mac_p);
415 if (error)
416 goto exec_fail;
417 #endif
418
419 /*
420 * Translate the file name. namei() returns a vnode pointer
421 * in ni_vp among other things.
422 *
423 * XXXAUDIT: It would be desirable to also audit the name of the
424 * interpreter if this is an interpreted binary.
425 */
426 if (args->fname != NULL) {
427 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME
428 | AUDITVNODE1, UIO_SYSSPACE, args->fname, td);
429 }
430
431 SDT_PROBE1(proc, , , exec, args->fname);
432
433 interpret:
434 if (args->fname != NULL) {
435 #ifdef CAPABILITY_MODE
436 /*
437 * While capability mode can't reach this point via direct
438 * path arguments to execve(), we also don't allow
439 * interpreters to be used in capability mode (for now).
440 * Catch indirect lookups and return a permissions error.
441 */
442 if (IN_CAPABILITY_MODE(td)) {
443 error = ECAPMODE;
444 goto exec_fail;
445 }
446 #endif
447 error = namei(&nd);
448 if (error)
449 goto exec_fail;
450
451 newtextvp = nd.ni_vp;
452 imgp->vp = newtextvp;
453 } else {
454 AUDIT_ARG_FD(args->fd);
455 /*
456 * Descriptors opened only with O_EXEC or O_RDONLY are allowed.
457 */
458 error = fgetvp_exec(td, args->fd,
459 cap_rights_init(&rights, CAP_FEXECVE), &newtextvp);
460 if (error)
461 goto exec_fail;
462 vn_lock(newtextvp, LK_EXCLUSIVE | LK_RETRY);
463 AUDIT_ARG_VNODE1(newtextvp);
464 imgp->vp = newtextvp;
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 /*
495 * Implement image setuid/setgid.
496 *
497 * Determine new credentials before attempting image activators
498 * so that it can be used by process_exec handlers to determine
499 * credential/setid changes.
500 *
501 * Don't honor setuid/setgid if the filesystem prohibits it or if
502 * the process is being traced.
503 *
504 * We disable setuid/setgid/etc in capability mode on the basis
505 * that most setugid applications are not written with that
506 * environment in mind, and will therefore almost certainly operate
507 * incorrectly. In principle there's no reason that setugid
508 * applications might not be useful in capability mode, so we may want
509 * to reconsider this conservative design choice in the future.
510 *
511 * XXXMAC: For the time being, use NOSUID to also prohibit
512 * transitions on the file system.
513 */
514 credential_changing = 0;
515 credential_changing |= (attr.va_mode & S_ISUID) &&
516 oldcred->cr_uid != attr.va_uid;
517 credential_changing |= (attr.va_mode & S_ISGID) &&
518 oldcred->cr_gid != attr.va_gid;
519 #ifdef MAC
520 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp,
521 interpvplabel, imgp);
522 credential_changing |= will_transition;
523 #endif
524
525 if (credential_changing &&
526 #ifdef CAPABILITY_MODE
527 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) &&
528 #endif
529 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 &&
530 (p->p_flag & P_TRACED) == 0) {
531 imgp->credential_setid = true;
532 VOP_UNLOCK(imgp->vp, 0);
533 imgp->newcred = crdup(oldcred);
534 if (attr.va_mode & S_ISUID) {
535 euip = uifind(attr.va_uid);
536 change_euid(imgp->newcred, euip);
537 }
538 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
539 if (attr.va_mode & S_ISGID)
540 change_egid(imgp->newcred, attr.va_gid);
541 /*
542 * Implement correct POSIX saved-id behavior.
543 *
544 * XXXMAC: Note that the current logic will save the
545 * uid and gid if a MAC domain transition occurs, even
546 * though maybe it shouldn't.
547 */
548 change_svuid(imgp->newcred, imgp->newcred->cr_uid);
549 change_svgid(imgp->newcred, imgp->newcred->cr_gid);
550 } else {
551 /*
552 * Implement correct POSIX saved-id behavior.
553 *
554 * XXX: It's not clear that the existing behavior is
555 * POSIX-compliant. A number of sources indicate that the
556 * saved uid/gid should only be updated if the new ruid is
557 * not equal to the old ruid, or the new euid is not equal
558 * to the old euid and the new euid is not equal to the old
559 * ruid. The FreeBSD code always updates the saved uid/gid.
560 * Also, this code uses the new (replaced) euid and egid as
561 * the source, which may or may not be the right ones to use.
562 */
563 if (oldcred->cr_svuid != oldcred->cr_uid ||
564 oldcred->cr_svgid != oldcred->cr_gid) {
565 VOP_UNLOCK(imgp->vp, 0);
566 imgp->newcred = crdup(oldcred);
567 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
568 change_svuid(imgp->newcred, imgp->newcred->cr_uid);
569 change_svgid(imgp->newcred, imgp->newcred->cr_gid);
570 }
571 }
572 /* The new credentials are installed into the process later. */
573
574 /*
575 * Do the best to calculate the full path to the image file.
576 */
577 if (args->fname != NULL && args->fname[0] == '/')
578 imgp->execpath = args->fname;
579 else {
580 VOP_UNLOCK(imgp->vp, 0);
581 if (vn_fullpath(td, imgp->vp, &imgp->execpath,
582 &imgp->freepath) != 0)
583 imgp->execpath = args->fname;
584 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
585 }
586
587 /*
588 * If the current process has a special image activator it
589 * wants to try first, call it. For example, emulating shell
590 * scripts differently.
591 */
592 error = -1;
593 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL)
594 error = img_first(imgp);
595
596 /*
597 * Loop through the list of image activators, calling each one.
598 * An activator returns -1 if there is no match, 0 on success,
599 * and an error otherwise.
600 */
601 for (i = 0; error == -1 && execsw[i]; ++i) {
602 if (execsw[i]->ex_imgact == NULL ||
603 execsw[i]->ex_imgact == img_first) {
604 continue;
605 }
606 error = (*execsw[i]->ex_imgact)(imgp);
607 }
608
609 if (error) {
610 if (error == -1) {
611 if (textset == 0)
612 VOP_UNSET_TEXT(imgp->vp);
613 error = ENOEXEC;
614 }
615 goto exec_fail_dealloc;
616 }
617
618 /*
619 * Special interpreter operation, cleanup and loop up to try to
620 * activate the interpreter.
621 */
622 if (imgp->interpreted) {
623 exec_unmap_first_page(imgp);
624 /*
625 * VV_TEXT needs to be unset for scripts. There is a short
626 * period before we determine that something is a script where
627 * VV_TEXT will be set. The vnode lock is held over this
628 * entire period so nothing should illegitimately be blocked.
629 */
630 VOP_UNSET_TEXT(imgp->vp);
631 /* free name buffer and old vnode */
632 if (args->fname != NULL)
633 NDFREE(&nd, NDF_ONLY_PNBUF);
634 #ifdef MAC
635 mac_execve_interpreter_enter(newtextvp, &interpvplabel);
636 #endif
637 if (imgp->opened) {
638 VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td);
639 imgp->opened = 0;
640 }
641 vput(newtextvp);
642 vm_object_deallocate(imgp->object);
643 imgp->object = NULL;
644 imgp->credential_setid = false;
645 if (imgp->newcred != NULL) {
646 crfree(imgp->newcred);
647 imgp->newcred = NULL;
648 }
649 imgp->execpath = NULL;
650 free(imgp->freepath, M_TEMP);
651 imgp->freepath = NULL;
652 /* set new name to that of the interpreter */
653 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME,
654 UIO_SYSSPACE, imgp->interpreter_name, td);
655 args->fname = imgp->interpreter_name;
656 goto interpret;
657 }
658
659 /*
660 * NB: We unlock the vnode here because it is believed that none
661 * of the sv_copyout_strings/sv_fixup operations require the vnode.
662 */
663 VOP_UNLOCK(imgp->vp, 0);
664
665 if (disallow_high_osrel &&
666 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) {
667 error = ENOEXEC;
668 uprintf("Osrel %d for image %s too high\n", p->p_osrel,
669 imgp->execpath != NULL ? imgp->execpath : "<unresolved>");
670 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
671 goto exec_fail_dealloc;
672 }
673
674 /*
675 * Copy out strings (args and env) and initialize stack base
676 */
677 if (p->p_sysent->sv_copyout_strings)
678 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp);
679 else
680 stack_base = exec_copyout_strings(imgp);
681
682 /*
683 * If custom stack fixup routine present for this process
684 * let it do the stack setup.
685 * Else stuff argument count as first item on stack
686 */
687 if (p->p_sysent->sv_fixup != NULL)
688 (*p->p_sysent->sv_fixup)(&stack_base, imgp);
689 else
690 suword(--stack_base, imgp->args->argc);
691
692 /*
693 * For security and other reasons, the file descriptor table cannot
694 * be shared after an exec.
695 */
696 fdunshare(td);
697 /* close files on exec */
698 fdcloseexec(td);
699
700 /*
701 * Malloc things before we need locks.
702 */
703 i = imgp->args->begin_envv - imgp->args->begin_argv;
704 /* Cache arguments if they fit inside our allowance */
705 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) {
706 newargs = pargs_alloc(i);
707 bcopy(imgp->args->begin_argv, newargs->ar_args, i);
708 }
709
710 /*
711 * For security and other reasons, signal handlers cannot
712 * be shared after an exec. The new process gets a copy of the old
713 * handlers. In execsigs(), the new process will have its signals
714 * reset.
715 */
716 if (sigacts_shared(p->p_sigacts)) {
717 oldsigacts = p->p_sigacts;
718 newsigacts = sigacts_alloc();
719 sigacts_copy(newsigacts, oldsigacts);
720 }
721
722 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
723
724 PROC_LOCK(p);
725 if (oldsigacts)
726 p->p_sigacts = newsigacts;
727 /* Stop profiling */
728 stopprofclock(p);
729
730 /* reset caught signals */
731 execsigs(p);
732
733 /* name this process - nameiexec(p, ndp) */
734 bzero(p->p_comm, sizeof(p->p_comm));
735 if (args->fname)
736 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm,
737 min(nd.ni_cnd.cn_namelen, MAXCOMLEN));
738 else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0)
739 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title));
740 bcopy(p->p_comm, td->td_name, sizeof(td->td_name));
741 #ifdef KTR
742 sched_clear_tdname(td);
743 #endif
744
745 /*
746 * mark as execed, wakeup the process that vforked (if any) and tell
747 * it that it now has its own resources back
748 */
749 p->p_flag |= P_EXEC;
750 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0)
751 p->p_flag2 &= ~P2_NOTRACE;
752 if (p->p_flag & P_PPWAIT) {
753 p->p_flag &= ~(P_PPWAIT | P_PPTRACE);
754 cv_broadcast(&p->p_pwait);
755 /* STOPs are no longer ignored, arrange for AST */
756 signotify(td);
757 }
758
759 /*
760 * Implement image setuid/setgid installation.
761 */
762 if (imgp->credential_setid) {
763 /*
764 * Turn off syscall tracing for set-id programs, except for
765 * root. Record any set-id flags first to make sure that
766 * we do not regain any tracing during a possible block.
767 */
768 setsugid(p);
769
770 #ifdef KTRACE
771 if (p->p_tracecred != NULL &&
772 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0))
773 ktrprocexec(p, &tracecred, &tracevp);
774 #endif
775 /*
776 * Close any file descriptors 0..2 that reference procfs,
777 * then make sure file descriptors 0..2 are in use.
778 *
779 * setugidsafety() may call closef() and then pfind()
780 * which may grab the process lock.
781 * fdcheckstd() may call falloc() which may block to
782 * allocate memory, so temporarily drop the process lock.
783 */
784 PROC_UNLOCK(p);
785 VOP_UNLOCK(imgp->vp, 0);
786 setugidsafety(td);
787 error = fdcheckstd(td);
788 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
789 if (error != 0)
790 goto exec_fail_dealloc;
791 PROC_LOCK(p);
792 #ifdef MAC
793 if (will_transition) {
794 mac_vnode_execve_transition(oldcred, imgp->newcred,
795 imgp->vp, interpvplabel, imgp);
796 }
797 #endif
798 } else {
799 if (oldcred->cr_uid == oldcred->cr_ruid &&
800 oldcred->cr_gid == oldcred->cr_rgid)
801 p->p_flag &= ~P_SUGID;
802 }
803 /*
804 * Set the new credentials.
805 */
806 if (imgp->newcred != NULL) {
807 proc_set_cred(p, imgp->newcred);
808 crfree(oldcred);
809 oldcred = NULL;
810 }
811
812 /*
813 * Store the vp for use in procfs. This vnode was referenced by namei
814 * or fgetvp_exec.
815 */
816 oldtextvp = p->p_textvp;
817 p->p_textvp = newtextvp;
818
819 #ifdef KDTRACE_HOOKS
820 /*
821 * Tell the DTrace fasttrap provider about the exec if it
822 * has declared an interest.
823 */
824 if (dtrace_fasttrap_exec)
825 dtrace_fasttrap_exec(p);
826 #endif
827
828 /*
829 * Notify others that we exec'd, and clear the P_INEXEC flag
830 * as we're now a bona fide freshly-execed process.
831 */
832 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC);
833 p->p_flag &= ~P_INEXEC;
834
835 /* clear "fork but no exec" flag, as we _are_ execing */
836 p->p_acflag &= ~AFORK;
837
838 /*
839 * Free any previous argument cache and replace it with
840 * the new argument cache, if any.
841 */
842 oldargs = p->p_args;
843 p->p_args = newargs;
844 newargs = NULL;
845
846 #ifdef HWPMC_HOOKS
847 /*
848 * Check if system-wide sampling is in effect or if the
849 * current process is using PMCs. If so, do exec() time
850 * processing. This processing needs to happen AFTER the
851 * P_INEXEC flag is cleared.
852 *
853 * The proc lock needs to be released before taking the PMC
854 * SX.
855 */
856 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) {
857 PROC_UNLOCK(p);
858 VOP_UNLOCK(imgp->vp, 0);
859 pe.pm_credentialschanged = credential_changing;
860 pe.pm_entryaddr = imgp->entry_addr;
861
862 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe);
863 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
864 } else
865 PROC_UNLOCK(p);
866 #else /* !HWPMC_HOOKS */
867 PROC_UNLOCK(p);
868 #endif
869
870 /* Set values passed into the program in registers. */
871 if (p->p_sysent->sv_setregs)
872 (*p->p_sysent->sv_setregs)(td, imgp,
873 (u_long)(uintptr_t)stack_base);
874 else
875 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base);
876
877 vfs_mark_atime(imgp->vp, td->td_ucred);
878
879 SDT_PROBE1(proc, , , exec__success, args->fname);
880
881 exec_fail_dealloc:
882 if (imgp->firstpage != NULL)
883 exec_unmap_first_page(imgp);
884
885 if (imgp->vp != NULL) {
886 if (args->fname)
887 NDFREE(&nd, NDF_ONLY_PNBUF);
888 if (imgp->opened)
889 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td);
890 if (error != 0)
891 vput(imgp->vp);
892 else
893 VOP_UNLOCK(imgp->vp, 0);
894 }
895
896 if (imgp->object != NULL)
897 vm_object_deallocate(imgp->object);
898
899 free(imgp->freepath, M_TEMP);
900
901 if (error == 0) {
902 PROC_LOCK(p);
903 if (p->p_ptevents & PTRACE_EXEC)
904 td->td_dbgflags |= TDB_EXEC;
905 PROC_UNLOCK(p);
906
907 /*
908 * Stop the process here if its stop event mask has
909 * the S_EXEC bit set.
910 */
911 STOPEVENT(p, S_EXEC, 0);
912 } else {
913 exec_fail:
914 /* we're done here, clear P_INEXEC */
915 PROC_LOCK(p);
916 p->p_flag &= ~P_INEXEC;
917 PROC_UNLOCK(p);
918
919 SDT_PROBE1(proc, , , exec__failure, error);
920 }
921
922 if (imgp->newcred != NULL && oldcred != NULL)
923 crfree(imgp->newcred);
924
925 #ifdef MAC
926 mac_execve_exit(imgp);
927 mac_execve_interpreter_exit(interpvplabel);
928 #endif
929 exec_free_args(args);
930
931 /*
932 * Handle deferred decrement of ref counts.
933 */
934 if (oldtextvp != NULL)
935 vrele(oldtextvp);
936 #ifdef KTRACE
937 if (tracevp != NULL)
938 vrele(tracevp);
939 if (tracecred != NULL)
940 crfree(tracecred);
941 #endif
942 pargs_drop(oldargs);
943 pargs_drop(newargs);
944 if (oldsigacts != NULL)
945 sigacts_free(oldsigacts);
946 if (euip != NULL)
947 uifree(euip);
948
949 if (error && imgp->vmspace_destroyed) {
950 /* sorry, no more process anymore. exit gracefully */
951 exit1(td, W_EXITCODE(0, SIGABRT));
952 /* NOT REACHED */
953 }
954
955 #ifdef KTRACE
956 if (error == 0)
957 ktrprocctor(p);
958 #endif
959
960 return (error);
961 }
962
963 int
exec_map_first_page(imgp)964 exec_map_first_page(imgp)
965 struct image_params *imgp;
966 {
967 int rv, i;
968 int initial_pagein;
969 vm_page_t ma[VM_INITIAL_PAGEIN];
970 vm_object_t object;
971
972 if (imgp->firstpage != NULL)
973 exec_unmap_first_page(imgp);
974
975 object = imgp->vp->v_object;
976 if (object == NULL)
977 return (EACCES);
978 VM_OBJECT_WLOCK(object);
979 #if VM_NRESERVLEVEL > 0
980 if ((object->flags & OBJ_COLORED) == 0) {
981 object->flags |= OBJ_COLORED;
982 object->pg_color = 0;
983 }
984 #endif
985 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL);
986 if (ma[0]->valid != VM_PAGE_BITS_ALL) {
987 initial_pagein = VM_INITIAL_PAGEIN;
988 if (initial_pagein > object->size)
989 initial_pagein = object->size;
990 for (i = 1; i < initial_pagein; i++) {
991 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) {
992 if (ma[i]->valid)
993 break;
994 if (!vm_page_tryxbusy(ma[i]))
995 break;
996 } else {
997 ma[i] = vm_page_alloc(object, i,
998 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED);
999 if (ma[i] == NULL)
1000 break;
1001 }
1002 }
1003 initial_pagein = i;
1004 rv = vm_pager_get_pages(object, ma, initial_pagein, 0);
1005 ma[0] = vm_page_lookup(object, 0);
1006 if ((rv != VM_PAGER_OK) || (ma[0] == NULL)) {
1007 if (ma[0] != NULL) {
1008 vm_page_lock(ma[0]);
1009 vm_page_free(ma[0]);
1010 vm_page_unlock(ma[0]);
1011 }
1012 VM_OBJECT_WUNLOCK(object);
1013 return (EIO);
1014 }
1015 }
1016 vm_page_xunbusy(ma[0]);
1017 vm_page_lock(ma[0]);
1018 vm_page_hold(ma[0]);
1019 vm_page_activate(ma[0]);
1020 vm_page_unlock(ma[0]);
1021 VM_OBJECT_WUNLOCK(object);
1022
1023 imgp->firstpage = sf_buf_alloc(ma[0], 0);
1024 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage);
1025
1026 return (0);
1027 }
1028
1029 void
exec_unmap_first_page(imgp)1030 exec_unmap_first_page(imgp)
1031 struct image_params *imgp;
1032 {
1033 vm_page_t m;
1034
1035 if (imgp->firstpage != NULL) {
1036 m = sf_buf_page(imgp->firstpage);
1037 sf_buf_free(imgp->firstpage);
1038 imgp->firstpage = NULL;
1039 vm_page_lock(m);
1040 vm_page_unhold(m);
1041 vm_page_unlock(m);
1042 }
1043 }
1044
1045 /*
1046 * Destroy old address space, and allocate a new stack.
1047 * The new stack is only sgrowsiz large because it is grown
1048 * automatically on a page fault.
1049 */
1050 int
exec_new_vmspace(imgp,sv)1051 exec_new_vmspace(imgp, sv)
1052 struct image_params *imgp;
1053 struct sysentvec *sv;
1054 {
1055 int error;
1056 struct proc *p = imgp->proc;
1057 struct vmspace *vmspace = p->p_vmspace;
1058 vm_object_t obj;
1059 struct rlimit rlim_stack;
1060 vm_offset_t sv_minuser, stack_addr;
1061 vm_map_t map;
1062 u_long ssiz;
1063
1064 imgp->vmspace_destroyed = 1;
1065 imgp->sysent = sv;
1066
1067 /* May be called with Giant held */
1068 EVENTHANDLER_INVOKE(process_exec, p, imgp);
1069
1070 /*
1071 * Blow away entire process VM, if address space not shared,
1072 * otherwise, create a new VM space so that other threads are
1073 * not disrupted
1074 */
1075 map = &vmspace->vm_map;
1076 if (map_at_zero)
1077 sv_minuser = sv->sv_minuser;
1078 else
1079 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE);
1080 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser &&
1081 vm_map_max(map) == sv->sv_maxuser) {
1082 shmexit(vmspace);
1083 pmap_remove_pages(vmspace_pmap(vmspace));
1084 vm_map_remove(map, vm_map_min(map), vm_map_max(map));
1085 /* An exec terminates mlockall(MCL_FUTURE). */
1086 vm_map_lock(map);
1087 vm_map_modflags(map, 0, MAP_WIREFUTURE);
1088 vm_map_unlock(map);
1089 } else {
1090 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser);
1091 if (error)
1092 return (error);
1093 vmspace = p->p_vmspace;
1094 map = &vmspace->vm_map;
1095 }
1096
1097 /* Map a shared page */
1098 obj = sv->sv_shared_page_obj;
1099 if (obj != NULL) {
1100 vm_object_reference(obj);
1101 error = vm_map_fixed(map, obj, 0,
1102 sv->sv_shared_page_base, sv->sv_shared_page_len,
1103 VM_PROT_READ | VM_PROT_EXECUTE,
1104 VM_PROT_READ | VM_PROT_EXECUTE,
1105 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE);
1106 if (error != KERN_SUCCESS) {
1107 vm_object_deallocate(obj);
1108 return (vm_mmap_to_errno(error));
1109 }
1110 }
1111
1112 /* Allocate a new stack */
1113 if (imgp->stack_sz != 0) {
1114 ssiz = trunc_page(imgp->stack_sz);
1115 PROC_LOCK(p);
1116 lim_rlimit(p, RLIMIT_STACK, &rlim_stack);
1117 PROC_UNLOCK(p);
1118 if (ssiz > rlim_stack.rlim_max)
1119 ssiz = rlim_stack.rlim_max;
1120 if (ssiz > rlim_stack.rlim_cur) {
1121 rlim_stack.rlim_cur = ssiz;
1122 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack);
1123 }
1124 } else if (sv->sv_maxssiz != NULL) {
1125 ssiz = *sv->sv_maxssiz;
1126 } else {
1127 ssiz = maxssiz;
1128 }
1129 stack_addr = sv->sv_usrstack - ssiz;
1130 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz,
1131 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot :
1132 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN);
1133 if (error != KERN_SUCCESS)
1134 return (vm_mmap_to_errno(error));
1135
1136 #ifdef __ia64__
1137 /* Allocate a new register stack */
1138 error = vm_map_stack(map, IA64_BACKINGSTORE, (vm_size_t)ssiz,
1139 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP);
1140 if (error)
1141 return (error);
1142 #endif
1143
1144 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the
1145 * VM_STACK case, but they are still used to monitor the size of the
1146 * process stack so we can check the stack rlimit.
1147 */
1148 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT;
1149 vmspace->vm_maxsaddr = (char *)stack_addr;
1150
1151 return (0);
1152 }
1153
1154 /*
1155 * Copy out argument and environment strings from the old process address
1156 * space into the temporary string buffer.
1157 */
1158 int
exec_copyin_args(struct image_args * args,char * fname,enum uio_seg segflg,char ** argv,char ** envv)1159 exec_copyin_args(struct image_args *args, char *fname,
1160 enum uio_seg segflg, char **argv, char **envv)
1161 {
1162 u_long argp, envp;
1163 int error;
1164 size_t length;
1165
1166 bzero(args, sizeof(*args));
1167 if (argv == NULL)
1168 return (EFAULT);
1169
1170 /*
1171 * Allocate demand-paged memory for the file name, argument, and
1172 * environment strings.
1173 */
1174 error = exec_alloc_args(args);
1175 if (error != 0)
1176 return (error);
1177
1178 /*
1179 * Copy the file name.
1180 */
1181 if (fname != NULL) {
1182 args->fname = args->buf;
1183 error = (segflg == UIO_SYSSPACE) ?
1184 copystr(fname, args->fname, PATH_MAX, &length) :
1185 copyinstr(fname, args->fname, PATH_MAX, &length);
1186 if (error != 0)
1187 goto err_exit;
1188 } else
1189 length = 0;
1190
1191 args->begin_argv = args->buf + length;
1192 args->endp = args->begin_argv;
1193 args->stringspace = ARG_MAX;
1194
1195 /*
1196 * extract arguments first
1197 */
1198 for (;;) {
1199 error = fueword(argv++, &argp);
1200 if (error == -1) {
1201 error = EFAULT;
1202 goto err_exit;
1203 }
1204 if (argp == 0)
1205 break;
1206 error = copyinstr((void *)(uintptr_t)argp, args->endp,
1207 args->stringspace, &length);
1208 if (error != 0) {
1209 if (error == ENAMETOOLONG)
1210 error = E2BIG;
1211 goto err_exit;
1212 }
1213 args->stringspace -= length;
1214 args->endp += length;
1215 args->argc++;
1216 }
1217
1218 args->begin_envv = args->endp;
1219
1220 /*
1221 * extract environment strings
1222 */
1223 if (envv) {
1224 for (;;) {
1225 error = fueword(envv++, &envp);
1226 if (error == -1) {
1227 error = EFAULT;
1228 goto err_exit;
1229 }
1230 if (envp == 0)
1231 break;
1232 error = copyinstr((void *)(uintptr_t)envp,
1233 args->endp, args->stringspace, &length);
1234 if (error != 0) {
1235 if (error == ENAMETOOLONG)
1236 error = E2BIG;
1237 goto err_exit;
1238 }
1239 args->stringspace -= length;
1240 args->endp += length;
1241 args->envc++;
1242 }
1243 }
1244
1245 return (0);
1246
1247 err_exit:
1248 exec_free_args(args);
1249 return (error);
1250 }
1251
1252 /*
1253 * Allocate temporary demand-paged, zero-filled memory for the file name,
1254 * argument, and environment strings. Returns zero if the allocation succeeds
1255 * and ENOMEM otherwise.
1256 */
1257 int
exec_alloc_args(struct image_args * args)1258 exec_alloc_args(struct image_args *args)
1259 {
1260
1261 args->buf = (char *)kmap_alloc_wait(exec_map, PATH_MAX + ARG_MAX);
1262 return (args->buf != NULL ? 0 : ENOMEM);
1263 }
1264
1265 void
exec_free_args(struct image_args * args)1266 exec_free_args(struct image_args *args)
1267 {
1268
1269 if (args->buf != NULL) {
1270 kmap_free_wakeup(exec_map, (vm_offset_t)args->buf,
1271 PATH_MAX + ARG_MAX);
1272 args->buf = NULL;
1273 }
1274 if (args->fname_buf != NULL) {
1275 free(args->fname_buf, M_TEMP);
1276 args->fname_buf = NULL;
1277 }
1278 }
1279
1280 /*
1281 * Copy strings out to the new process address space, constructing new arg
1282 * and env vector tables. Return a pointer to the base so that it can be used
1283 * as the initial stack pointer.
1284 */
1285 register_t *
exec_copyout_strings(imgp)1286 exec_copyout_strings(imgp)
1287 struct image_params *imgp;
1288 {
1289 int argc, envc;
1290 char **vectp;
1291 char *stringp;
1292 uintptr_t destp;
1293 register_t *stack_base;
1294 struct ps_strings *arginfo;
1295 struct proc *p;
1296 size_t execpath_len;
1297 int szsigcode, szps;
1298 char canary[sizeof(long) * 8];
1299
1300 szps = sizeof(pagesizes[0]) * MAXPAGESIZES;
1301 /*
1302 * Calculate string base and vector table pointers.
1303 * Also deal with signal trampoline code for this exec type.
1304 */
1305 if (imgp->execpath != NULL && imgp->auxargs != NULL)
1306 execpath_len = strlen(imgp->execpath) + 1;
1307 else
1308 execpath_len = 0;
1309 p = imgp->proc;
1310 szsigcode = 0;
1311 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings;
1312 if (p->p_sysent->sv_sigcode_base == 0) {
1313 if (p->p_sysent->sv_szsigcode != NULL)
1314 szsigcode = *(p->p_sysent->sv_szsigcode);
1315 }
1316 destp = (uintptr_t)arginfo;
1317
1318 /*
1319 * install sigcode
1320 */
1321 if (szsigcode != 0) {
1322 destp -= szsigcode;
1323 destp = rounddown2(destp, sizeof(void *));
1324 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode);
1325 }
1326
1327 /*
1328 * Copy the image path for the rtld.
1329 */
1330 if (execpath_len != 0) {
1331 destp -= execpath_len;
1332 imgp->execpathp = destp;
1333 copyout(imgp->execpath, (void *)destp, execpath_len);
1334 }
1335
1336 /*
1337 * Prepare the canary for SSP.
1338 */
1339 arc4rand(canary, sizeof(canary), 0);
1340 destp -= sizeof(canary);
1341 imgp->canary = destp;
1342 copyout(canary, (void *)destp, sizeof(canary));
1343 imgp->canarylen = sizeof(canary);
1344
1345 /*
1346 * Prepare the pagesizes array.
1347 */
1348 destp -= szps;
1349 destp = rounddown2(destp, sizeof(void *));
1350 imgp->pagesizes = destp;
1351 copyout(pagesizes, (void *)destp, szps);
1352 imgp->pagesizeslen = szps;
1353
1354 destp -= ARG_MAX - imgp->args->stringspace;
1355 destp = rounddown2(destp, sizeof(void *));
1356
1357 /*
1358 * If we have a valid auxargs ptr, prepare some room
1359 * on the stack.
1360 */
1361 if (imgp->auxargs) {
1362 /*
1363 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for
1364 * lower compatibility.
1365 */
1366 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size :
1367 (AT_COUNT * 2);
1368 /*
1369 * The '+ 2' is for the null pointers at the end of each of
1370 * the arg and env vector sets,and imgp->auxarg_size is room
1371 * for argument of Runtime loader.
1372 */
1373 vectp = (char **)(destp - (imgp->args->argc +
1374 imgp->args->envc + 2 + imgp->auxarg_size)
1375 * sizeof(char *));
1376 } else {
1377 /*
1378 * The '+ 2' is for the null pointers at the end of each of
1379 * the arg and env vector sets
1380 */
1381 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc
1382 + 2) * sizeof(char *));
1383 }
1384
1385 /*
1386 * vectp also becomes our initial stack base
1387 */
1388 stack_base = (register_t *)vectp;
1389
1390 stringp = imgp->args->begin_argv;
1391 argc = imgp->args->argc;
1392 envc = imgp->args->envc;
1393
1394 /*
1395 * Copy out strings - arguments and environment.
1396 */
1397 copyout(stringp, (void *)destp, ARG_MAX - imgp->args->stringspace);
1398
1399 /*
1400 * Fill in "ps_strings" struct for ps, w, etc.
1401 */
1402 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp);
1403 suword32(&arginfo->ps_nargvstr, argc);
1404
1405 /*
1406 * Fill in argument portion of vector table.
1407 */
1408 for (; argc > 0; --argc) {
1409 suword(vectp++, (long)(intptr_t)destp);
1410 while (*stringp++ != 0)
1411 destp++;
1412 destp++;
1413 }
1414
1415 /* a null vector table pointer separates the argp's from the envp's */
1416 suword(vectp++, 0);
1417
1418 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp);
1419 suword32(&arginfo->ps_nenvstr, envc);
1420
1421 /*
1422 * Fill in environment portion of vector table.
1423 */
1424 for (; envc > 0; --envc) {
1425 suword(vectp++, (long)(intptr_t)destp);
1426 while (*stringp++ != 0)
1427 destp++;
1428 destp++;
1429 }
1430
1431 /* end of vector table is a null pointer */
1432 suword(vectp, 0);
1433
1434 return (stack_base);
1435 }
1436
1437 /*
1438 * Check permissions of file to execute.
1439 * Called with imgp->vp locked.
1440 * Return 0 for success or error code on failure.
1441 */
1442 int
exec_check_permissions(imgp)1443 exec_check_permissions(imgp)
1444 struct image_params *imgp;
1445 {
1446 struct vnode *vp = imgp->vp;
1447 struct vattr *attr = imgp->attr;
1448 struct thread *td;
1449 int error, writecount;
1450
1451 td = curthread;
1452
1453 /* Get file attributes */
1454 error = VOP_GETATTR(vp, attr, td->td_ucred);
1455 if (error)
1456 return (error);
1457
1458 #ifdef MAC
1459 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp);
1460 if (error)
1461 return (error);
1462 #endif
1463
1464 /*
1465 * 1) Check if file execution is disabled for the filesystem that
1466 * this file resides on.
1467 * 2) Ensure that at least one execute bit is on. Otherwise, a
1468 * privileged user will always succeed, and we don't want this
1469 * to happen unless the file really is executable.
1470 * 3) Ensure that the file is a regular file.
1471 */
1472 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) ||
1473 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 ||
1474 (attr->va_type != VREG))
1475 return (EACCES);
1476
1477 /*
1478 * Zero length files can't be exec'd
1479 */
1480 if (attr->va_size == 0)
1481 return (ENOEXEC);
1482
1483 /*
1484 * Check for execute permission to file based on current credentials.
1485 */
1486 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td);
1487 if (error)
1488 return (error);
1489
1490 /*
1491 * Check number of open-for-writes on the file and deny execution
1492 * if there are any.
1493 */
1494 error = VOP_GET_WRITECOUNT(vp, &writecount);
1495 if (error != 0)
1496 return (error);
1497 if (writecount != 0)
1498 return (ETXTBSY);
1499
1500 /*
1501 * Call filesystem specific open routine (which does nothing in the
1502 * general case).
1503 */
1504 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL);
1505 if (error == 0)
1506 imgp->opened = 1;
1507 return (error);
1508 }
1509
1510 /*
1511 * Exec handler registration
1512 */
1513 int
exec_register(execsw_arg)1514 exec_register(execsw_arg)
1515 const struct execsw *execsw_arg;
1516 {
1517 const struct execsw **es, **xs, **newexecsw;
1518 int count = 2; /* New slot and trailing NULL */
1519
1520 if (execsw)
1521 for (es = execsw; *es; es++)
1522 count++;
1523 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
1524 xs = newexecsw;
1525 if (execsw)
1526 for (es = execsw; *es; es++)
1527 *xs++ = *es;
1528 *xs++ = execsw_arg;
1529 *xs = NULL;
1530 if (execsw)
1531 free(execsw, M_TEMP);
1532 execsw = newexecsw;
1533 return (0);
1534 }
1535
1536 int
exec_unregister(execsw_arg)1537 exec_unregister(execsw_arg)
1538 const struct execsw *execsw_arg;
1539 {
1540 const struct execsw **es, **xs, **newexecsw;
1541 int count = 1;
1542
1543 if (execsw == NULL)
1544 panic("unregister with no handlers left?\n");
1545
1546 for (es = execsw; *es; es++) {
1547 if (*es == execsw_arg)
1548 break;
1549 }
1550 if (*es == NULL)
1551 return (ENOENT);
1552 for (es = execsw; *es; es++)
1553 if (*es != execsw_arg)
1554 count++;
1555 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
1556 xs = newexecsw;
1557 for (es = execsw; *es; es++)
1558 if (*es != execsw_arg)
1559 *xs++ = *es;
1560 *xs = NULL;
1561 if (execsw)
1562 free(execsw, M_TEMP);
1563 execsw = newexecsw;
1564 return (0);
1565 }
1566