FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_exec.c
1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 1993, David Greenman
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD: releng/12.0/sys/kern/kern_exec.c 337965 2018-08-17 14:35:10Z oshogbo $");
31
32 #include "opt_capsicum.h"
33 #include "opt_hwpmc_hooks.h"
34 #include "opt_ktrace.h"
35 #include "opt_vm.h"
36
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/acct.h>
40 #include <sys/capsicum.h>
41 #include <sys/eventhandler.h>
42 #include <sys/exec.h>
43 #include <sys/fcntl.h>
44 #include <sys/filedesc.h>
45 #include <sys/imgact.h>
46 #include <sys/imgact_elf.h>
47 #include <sys/kernel.h>
48 #include <sys/lock.h>
49 #include <sys/malloc.h>
50 #include <sys/mman.h>
51 #include <sys/mount.h>
52 #include <sys/mutex.h>
53 #include <sys/namei.h>
54 #include <sys/pioctl.h>
55 #include <sys/priv.h>
56 #include <sys/proc.h>
57 #include <sys/ptrace.h>
58 #include <sys/resourcevar.h>
59 #include <sys/rwlock.h>
60 #include <sys/sched.h>
61 #include <sys/sdt.h>
62 #include <sys/sf_buf.h>
63 #include <sys/shm.h>
64 #include <sys/signalvar.h>
65 #include <sys/smp.h>
66 #include <sys/stat.h>
67 #include <sys/syscallsubr.h>
68 #include <sys/sysctl.h>
69 #include <sys/sysent.h>
70 #include <sys/sysproto.h>
71 #include <sys/vnode.h>
72 #include <sys/wait.h>
73 #ifdef KTRACE
74 #include <sys/ktrace.h>
75 #endif
76
77 #include <vm/vm.h>
78 #include <vm/vm_param.h>
79 #include <vm/pmap.h>
80 #include <vm/vm_page.h>
81 #include <vm/vm_map.h>
82 #include <vm/vm_kern.h>
83 #include <vm/vm_extern.h>
84 #include <vm/vm_object.h>
85 #include <vm/vm_pager.h>
86
87 #ifdef HWPMC_HOOKS
88 #include <sys/pmckern.h>
89 #endif
90
91 #include <machine/reg.h>
92
93 #include <security/audit/audit.h>
94 #include <security/mac/mac_framework.h>
95
96 #ifdef KDTRACE_HOOKS
97 #include <sys/dtrace_bsd.h>
98 dtrace_execexit_func_t dtrace_fasttrap_exec;
99 #endif
100
101 SDT_PROVIDER_DECLARE(proc);
102 SDT_PROBE_DEFINE1(proc, , , exec, "char *");
103 SDT_PROBE_DEFINE1(proc, , , exec__failure, "int");
104 SDT_PROBE_DEFINE1(proc, , , exec__success, "char *");
105
106 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments");
107
108 int coredump_pack_fileinfo = 1;
109 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_fileinfo, CTLFLAG_RWTUN,
110 &coredump_pack_fileinfo, 0,
111 "Enable file path packing in 'procstat -f' coredump notes");
112
113 int coredump_pack_vmmapinfo = 1;
114 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_vmmapinfo, CTLFLAG_RWTUN,
115 &coredump_pack_vmmapinfo, 0,
116 "Enable file path packing in 'procstat -v' coredump notes");
117
118 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS);
119 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS);
120 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS);
121 static int do_execve(struct thread *td, struct image_args *args,
122 struct mac *mac_p);
123
124 /* XXX This should be vm_size_t. */
125 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD|
126 CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_ps_strings, "LU", "");
127
128 /* XXX This should be vm_size_t. */
129 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD|
130 CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_usrstack, "LU", "");
131
132 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD|CTLFLAG_MPSAFE,
133 NULL, 0, sysctl_kern_stackprot, "I", "");
134
135 u_long ps_arg_cache_limit = PAGE_SIZE / 16;
136 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW,
137 &ps_arg_cache_limit, 0, "");
138
139 static int disallow_high_osrel;
140 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW,
141 &disallow_high_osrel, 0,
142 "Disallow execution of binaries built for higher version of the world");
143
144 static int map_at_zero = 0;
145 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RWTUN, &map_at_zero, 0,
146 "Permit processes to map an object at virtual address 0.");
147
148 EVENTHANDLER_LIST_DECLARE(process_exec);
149
150 static int
151 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)
152 {
153 struct proc *p;
154 int error;
155
156 p = curproc;
157 #ifdef SCTL_MASK32
158 if (req->flags & SCTL_MASK32) {
159 unsigned int val;
160 val = (unsigned int)p->p_sysent->sv_psstrings;
161 error = SYSCTL_OUT(req, &val, sizeof(val));
162 } else
163 #endif
164 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings,
165 sizeof(p->p_sysent->sv_psstrings));
166 return error;
167 }
168
169 static int
170 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)
171 {
172 struct proc *p;
173 int error;
174
175 p = curproc;
176 #ifdef SCTL_MASK32
177 if (req->flags & SCTL_MASK32) {
178 unsigned int val;
179 val = (unsigned int)p->p_sysent->sv_usrstack;
180 error = SYSCTL_OUT(req, &val, sizeof(val));
181 } else
182 #endif
183 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack,
184 sizeof(p->p_sysent->sv_usrstack));
185 return error;
186 }
187
188 static int
189 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS)
190 {
191 struct proc *p;
192
193 p = curproc;
194 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot,
195 sizeof(p->p_sysent->sv_stackprot)));
196 }
197
198 /*
199 * Each of the items is a pointer to a `const struct execsw', hence the
200 * double pointer here.
201 */
202 static const struct execsw **execsw;
203
204 #ifndef _SYS_SYSPROTO_H_
205 struct execve_args {
206 char *fname;
207 char **argv;
208 char **envv;
209 };
210 #endif
211
212 int
213 sys_execve(struct thread *td, struct execve_args *uap)
214 {
215 struct image_args args;
216 struct vmspace *oldvmspace;
217 int error;
218
219 error = pre_execve(td, &oldvmspace);
220 if (error != 0)
221 return (error);
222 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
223 uap->argv, uap->envv);
224 if (error == 0)
225 error = kern_execve(td, &args, NULL);
226 post_execve(td, error, oldvmspace);
227 return (error);
228 }
229
230 #ifndef _SYS_SYSPROTO_H_
231 struct fexecve_args {
232 int fd;
233 char **argv;
234 char **envv;
235 }
236 #endif
237 int
238 sys_fexecve(struct thread *td, struct fexecve_args *uap)
239 {
240 struct image_args args;
241 struct vmspace *oldvmspace;
242 int error;
243
244 error = pre_execve(td, &oldvmspace);
245 if (error != 0)
246 return (error);
247 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE,
248 uap->argv, uap->envv);
249 if (error == 0) {
250 args.fd = uap->fd;
251 error = kern_execve(td, &args, NULL);
252 }
253 post_execve(td, error, oldvmspace);
254 return (error);
255 }
256
257 #ifndef _SYS_SYSPROTO_H_
258 struct __mac_execve_args {
259 char *fname;
260 char **argv;
261 char **envv;
262 struct mac *mac_p;
263 };
264 #endif
265
266 int
267 sys___mac_execve(struct thread *td, struct __mac_execve_args *uap)
268 {
269 #ifdef MAC
270 struct image_args args;
271 struct vmspace *oldvmspace;
272 int error;
273
274 error = pre_execve(td, &oldvmspace);
275 if (error != 0)
276 return (error);
277 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
278 uap->argv, uap->envv);
279 if (error == 0)
280 error = kern_execve(td, &args, uap->mac_p);
281 post_execve(td, error, oldvmspace);
282 return (error);
283 #else
284 return (ENOSYS);
285 #endif
286 }
287
288 int
289 pre_execve(struct thread *td, struct vmspace **oldvmspace)
290 {
291 struct proc *p;
292 int error;
293
294 KASSERT(td == curthread, ("non-current thread %p", td));
295 error = 0;
296 p = td->td_proc;
297 if ((p->p_flag & P_HADTHREADS) != 0) {
298 PROC_LOCK(p);
299 if (thread_single(p, SINGLE_BOUNDARY) != 0)
300 error = ERESTART;
301 PROC_UNLOCK(p);
302 }
303 KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0,
304 ("nested execve"));
305 *oldvmspace = p->p_vmspace;
306 return (error);
307 }
308
309 void
310 post_execve(struct thread *td, int error, struct vmspace *oldvmspace)
311 {
312 struct proc *p;
313
314 KASSERT(td == curthread, ("non-current thread %p", td));
315 p = td->td_proc;
316 if ((p->p_flag & P_HADTHREADS) != 0) {
317 PROC_LOCK(p);
318 /*
319 * If success, we upgrade to SINGLE_EXIT state to
320 * force other threads to suicide.
321 */
322 if (error == EJUSTRETURN)
323 thread_single(p, SINGLE_EXIT);
324 else
325 thread_single_end(p, SINGLE_BOUNDARY);
326 PROC_UNLOCK(p);
327 }
328 if ((td->td_pflags & TDP_EXECVMSPC) != 0) {
329 KASSERT(p->p_vmspace != oldvmspace,
330 ("oldvmspace still used"));
331 vmspace_free(oldvmspace);
332 td->td_pflags &= ~TDP_EXECVMSPC;
333 }
334 }
335
336 /*
337 * XXX: kern_execve has the astonishing property of not always returning to
338 * the caller. If sufficiently bad things happen during the call to
339 * do_execve(), it can end up calling exit1(); as a result, callers must
340 * avoid doing anything which they might need to undo (e.g., allocating
341 * memory).
342 */
343 int
344 kern_execve(struct thread *td, struct image_args *args, struct mac *mac_p)
345 {
346
347 AUDIT_ARG_ARGV(args->begin_argv, args->argc,
348 args->begin_envv - args->begin_argv);
349 AUDIT_ARG_ENVV(args->begin_envv, args->envc,
350 args->endp - args->begin_envv);
351 return (do_execve(td, args, mac_p));
352 }
353
354 /*
355 * In-kernel implementation of execve(). All arguments are assumed to be
356 * userspace pointers from the passed thread.
357 */
358 static int
359 do_execve(struct thread *td, struct image_args *args, 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 int credential_changing;
378 int textset;
379 #ifdef MAC
380 struct label *interpvplabel = NULL;
381 int will_transition;
382 #endif
383 #ifdef HWPMC_HOOKS
384 struct pmckern_procexec pe;
385 #endif
386 static const char fexecv_proc_title[] = "(fexecv)";
387
388 imgp = &image_params;
389
390 /*
391 * Lock the process and set the P_INEXEC flag to indicate that
392 * it should be left alone until we're done here. This is
393 * necessary to avoid race conditions - e.g. in ptrace() -
394 * that might allow a local user to illicitly obtain elevated
395 * privileges.
396 */
397 PROC_LOCK(p);
398 KASSERT((p->p_flag & P_INEXEC) == 0,
399 ("%s(): process already has P_INEXEC flag", __func__));
400 p->p_flag |= P_INEXEC;
401 PROC_UNLOCK(p);
402
403 /*
404 * Initialize part of the common data
405 */
406 bzero(imgp, sizeof(*imgp));
407 imgp->proc = p;
408 imgp->attr = &attr;
409 imgp->args = args;
410 oldcred = p->p_ucred;
411
412 #ifdef MAC
413 error = mac_execve_enter(imgp, mac_p);
414 if (error)
415 goto exec_fail;
416 #endif
417
418 /*
419 * Translate the file name. namei() returns a vnode pointer
420 * in ni_vp among other things.
421 *
422 * XXXAUDIT: It would be desirable to also audit the name of the
423 * interpreter if this is an interpreted binary.
424 */
425 if (args->fname != NULL) {
426 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME
427 | AUDITVNODE1, UIO_SYSSPACE, args->fname, td);
428 }
429
430 SDT_PROBE1(proc, , , exec, args->fname);
431
432 interpret:
433 if (args->fname != NULL) {
434 #ifdef CAPABILITY_MODE
435 /*
436 * While capability mode can't reach this point via direct
437 * path arguments to execve(), we also don't allow
438 * interpreters to be used in capability mode (for now).
439 * Catch indirect lookups and return a permissions error.
440 */
441 if (IN_CAPABILITY_MODE(td)) {
442 error = ECAPMODE;
443 goto exec_fail;
444 }
445 #endif
446 error = namei(&nd);
447 if (error)
448 goto exec_fail;
449
450 newtextvp = nd.ni_vp;
451 imgp->vp = newtextvp;
452 } else {
453 AUDIT_ARG_FD(args->fd);
454 /*
455 * Descriptors opened only with O_EXEC or O_RDONLY are allowed.
456 */
457 error = fgetvp_exec(td, args->fd, &cap_fexecve_rights, &newtextvp);
458 if (error)
459 goto exec_fail;
460 vn_lock(newtextvp, LK_EXCLUSIVE | LK_RETRY);
461 AUDIT_ARG_VNODE1(newtextvp);
462 imgp->vp = newtextvp;
463 }
464
465 /*
466 * Check file permissions (also 'opens' file)
467 */
468 error = exec_check_permissions(imgp);
469 if (error)
470 goto exec_fail_dealloc;
471
472 imgp->object = imgp->vp->v_object;
473 if (imgp->object != NULL)
474 vm_object_reference(imgp->object);
475
476 /*
477 * Set VV_TEXT now so no one can write to the executable while we're
478 * activating it.
479 *
480 * Remember if this was set before and unset it in case this is not
481 * actually an executable image.
482 */
483 textset = VOP_IS_TEXT(imgp->vp);
484 VOP_SET_TEXT(imgp->vp);
485
486 error = exec_map_first_page(imgp);
487 if (error)
488 goto exec_fail_dealloc;
489
490 imgp->proc->p_osrel = 0;
491
492 /*
493 * Implement image setuid/setgid.
494 *
495 * Determine new credentials before attempting image activators
496 * so that it can be used by process_exec handlers to determine
497 * credential/setid changes.
498 *
499 * Don't honor setuid/setgid if the filesystem prohibits it or if
500 * the process is being traced.
501 *
502 * We disable setuid/setgid/etc in capability mode on the basis
503 * that most setugid applications are not written with that
504 * environment in mind, and will therefore almost certainly operate
505 * incorrectly. In principle there's no reason that setugid
506 * applications might not be useful in capability mode, so we may want
507 * to reconsider this conservative design choice in the future.
508 *
509 * XXXMAC: For the time being, use NOSUID to also prohibit
510 * transitions on the file system.
511 */
512 credential_changing = 0;
513 credential_changing |= (attr.va_mode & S_ISUID) &&
514 oldcred->cr_uid != attr.va_uid;
515 credential_changing |= (attr.va_mode & S_ISGID) &&
516 oldcred->cr_gid != attr.va_gid;
517 #ifdef MAC
518 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp,
519 interpvplabel, imgp);
520 credential_changing |= will_transition;
521 #endif
522
523 /* Don't inherit PROC_PDEATHSIG_CTL value if setuid/setgid. */
524 if (credential_changing)
525 imgp->proc->p_pdeathsig = 0;
526
527 if (credential_changing &&
528 #ifdef CAPABILITY_MODE
529 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) &&
530 #endif
531 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 &&
532 (p->p_flag & P_TRACED) == 0) {
533 imgp->credential_setid = true;
534 VOP_UNLOCK(imgp->vp, 0);
535 imgp->newcred = crdup(oldcred);
536 if (attr.va_mode & S_ISUID) {
537 euip = uifind(attr.va_uid);
538 change_euid(imgp->newcred, euip);
539 }
540 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
541 if (attr.va_mode & S_ISGID)
542 change_egid(imgp->newcred, attr.va_gid);
543 /*
544 * Implement correct POSIX saved-id behavior.
545 *
546 * XXXMAC: Note that the current logic will save the
547 * uid and gid if a MAC domain transition occurs, even
548 * though maybe it shouldn't.
549 */
550 change_svuid(imgp->newcred, imgp->newcred->cr_uid);
551 change_svgid(imgp->newcred, imgp->newcred->cr_gid);
552 } else {
553 /*
554 * Implement correct POSIX saved-id behavior.
555 *
556 * XXX: It's not clear that the existing behavior is
557 * POSIX-compliant. A number of sources indicate that the
558 * saved uid/gid should only be updated if the new ruid is
559 * not equal to the old ruid, or the new euid is not equal
560 * to the old euid and the new euid is not equal to the old
561 * ruid. The FreeBSD code always updates the saved uid/gid.
562 * Also, this code uses the new (replaced) euid and egid as
563 * the source, which may or may not be the right ones to use.
564 */
565 if (oldcred->cr_svuid != oldcred->cr_uid ||
566 oldcred->cr_svgid != oldcred->cr_gid) {
567 VOP_UNLOCK(imgp->vp, 0);
568 imgp->newcred = crdup(oldcred);
569 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
570 change_svuid(imgp->newcred, imgp->newcred->cr_uid);
571 change_svgid(imgp->newcred, imgp->newcred->cr_gid);
572 }
573 }
574 /* The new credentials are installed into the process later. */
575
576 /*
577 * Do the best to calculate the full path to the image file.
578 */
579 if (args->fname != NULL && args->fname[0] == '/')
580 imgp->execpath = args->fname;
581 else {
582 VOP_UNLOCK(imgp->vp, 0);
583 if (vn_fullpath(td, imgp->vp, &imgp->execpath,
584 &imgp->freepath) != 0)
585 imgp->execpath = args->fname;
586 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
587 }
588
589 /*
590 * If the current process has a special image activator it
591 * wants to try first, call it. For example, emulating shell
592 * scripts differently.
593 */
594 error = -1;
595 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL)
596 error = img_first(imgp);
597
598 /*
599 * Loop through the list of image activators, calling each one.
600 * An activator returns -1 if there is no match, 0 on success,
601 * and an error otherwise.
602 */
603 for (i = 0; error == -1 && execsw[i]; ++i) {
604 if (execsw[i]->ex_imgact == NULL ||
605 execsw[i]->ex_imgact == img_first) {
606 continue;
607 }
608 error = (*execsw[i]->ex_imgact)(imgp);
609 }
610
611 if (error) {
612 if (error == -1) {
613 if (textset == 0)
614 VOP_UNSET_TEXT(imgp->vp);
615 error = ENOEXEC;
616 }
617 goto exec_fail_dealloc;
618 }
619
620 /*
621 * Special interpreter operation, cleanup and loop up to try to
622 * activate the interpreter.
623 */
624 if (imgp->interpreted) {
625 exec_unmap_first_page(imgp);
626 /*
627 * VV_TEXT needs to be unset for scripts. There is a short
628 * period before we determine that something is a script where
629 * VV_TEXT will be set. The vnode lock is held over this
630 * entire period so nothing should illegitimately be blocked.
631 */
632 VOP_UNSET_TEXT(imgp->vp);
633 /* free name buffer and old vnode */
634 if (args->fname != NULL)
635 NDFREE(&nd, NDF_ONLY_PNBUF);
636 #ifdef MAC
637 mac_execve_interpreter_enter(newtextvp, &interpvplabel);
638 #endif
639 if (imgp->opened) {
640 VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td);
641 imgp->opened = 0;
642 }
643 vput(newtextvp);
644 vm_object_deallocate(imgp->object);
645 imgp->object = NULL;
646 imgp->credential_setid = false;
647 if (imgp->newcred != NULL) {
648 crfree(imgp->newcred);
649 imgp->newcred = NULL;
650 }
651 imgp->execpath = NULL;
652 free(imgp->freepath, M_TEMP);
653 imgp->freepath = NULL;
654 /* set new name to that of the interpreter */
655 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME,
656 UIO_SYSSPACE, imgp->interpreter_name, td);
657 args->fname = imgp->interpreter_name;
658 goto interpret;
659 }
660
661 /*
662 * NB: We unlock the vnode here because it is believed that none
663 * of the sv_copyout_strings/sv_fixup operations require the vnode.
664 */
665 VOP_UNLOCK(imgp->vp, 0);
666
667 if (disallow_high_osrel &&
668 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) {
669 error = ENOEXEC;
670 uprintf("Osrel %d for image %s too high\n", p->p_osrel,
671 imgp->execpath != NULL ? imgp->execpath : "<unresolved>");
672 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
673 goto exec_fail_dealloc;
674 }
675
676 /* ABI enforces the use of Capsicum. Switch into capabilities mode. */
677 if (SV_PROC_FLAG(p, SV_CAPSICUM))
678 sys_cap_enter(td, NULL);
679
680 /*
681 * Copy out strings (args and env) and initialize stack base
682 */
683 if (p->p_sysent->sv_copyout_strings)
684 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp);
685 else
686 stack_base = exec_copyout_strings(imgp);
687
688 /*
689 * If custom stack fixup routine present for this process
690 * let it do the stack setup.
691 * Else stuff argument count as first item on stack
692 */
693 if (p->p_sysent->sv_fixup != NULL)
694 error = (*p->p_sysent->sv_fixup)(&stack_base, imgp);
695 else
696 error = suword(--stack_base, imgp->args->argc) == 0 ?
697 0 : EFAULT;
698 if (error != 0)
699 goto exec_fail_dealloc;
700
701 if (args->fdp != NULL) {
702 /* Install a brand new file descriptor table. */
703 fdinstall_remapped(td, args->fdp);
704 args->fdp = NULL;
705 } else {
706 /*
707 * Keep on using the existing file descriptor table. For
708 * security and other reasons, the file descriptor table
709 * cannot be shared after an exec.
710 */
711 fdunshare(td);
712 /* close files on exec */
713 fdcloseexec(td);
714 }
715
716 /*
717 * Malloc things before we need locks.
718 */
719 i = imgp->args->begin_envv - imgp->args->begin_argv;
720 /* Cache arguments if they fit inside our allowance */
721 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) {
722 newargs = pargs_alloc(i);
723 bcopy(imgp->args->begin_argv, newargs->ar_args, i);
724 }
725
726 /*
727 * For security and other reasons, signal handlers cannot
728 * be shared after an exec. The new process gets a copy of the old
729 * handlers. In execsigs(), the new process will have its signals
730 * reset.
731 */
732 if (sigacts_shared(p->p_sigacts)) {
733 oldsigacts = p->p_sigacts;
734 newsigacts = sigacts_alloc();
735 sigacts_copy(newsigacts, oldsigacts);
736 }
737
738 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
739
740 PROC_LOCK(p);
741 if (oldsigacts)
742 p->p_sigacts = newsigacts;
743 /* Stop profiling */
744 stopprofclock(p);
745
746 /* reset caught signals */
747 execsigs(p);
748
749 /* name this process - nameiexec(p, ndp) */
750 bzero(p->p_comm, sizeof(p->p_comm));
751 if (args->fname)
752 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm,
753 min(nd.ni_cnd.cn_namelen, MAXCOMLEN));
754 else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0)
755 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title));
756 bcopy(p->p_comm, td->td_name, sizeof(td->td_name));
757 #ifdef KTR
758 sched_clear_tdname(td);
759 #endif
760
761 /*
762 * mark as execed, wakeup the process that vforked (if any) and tell
763 * it that it now has its own resources back
764 */
765 p->p_flag |= P_EXEC;
766 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0)
767 p->p_flag2 &= ~P2_NOTRACE;
768 if (p->p_flag & P_PPWAIT) {
769 p->p_flag &= ~(P_PPWAIT | P_PPTRACE);
770 cv_broadcast(&p->p_pwait);
771 /* STOPs are no longer ignored, arrange for AST */
772 signotify(td);
773 }
774
775 /*
776 * Implement image setuid/setgid installation.
777 */
778 if (imgp->credential_setid) {
779 /*
780 * Turn off syscall tracing for set-id programs, except for
781 * root. Record any set-id flags first to make sure that
782 * we do not regain any tracing during a possible block.
783 */
784 setsugid(p);
785
786 #ifdef KTRACE
787 if (p->p_tracecred != NULL &&
788 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0))
789 ktrprocexec(p, &tracecred, &tracevp);
790 #endif
791 /*
792 * Close any file descriptors 0..2 that reference procfs,
793 * then make sure file descriptors 0..2 are in use.
794 *
795 * Both fdsetugidsafety() and fdcheckstd() may call functions
796 * taking sleepable locks, so temporarily drop our locks.
797 */
798 PROC_UNLOCK(p);
799 VOP_UNLOCK(imgp->vp, 0);
800 fdsetugidsafety(td);
801 error = fdcheckstd(td);
802 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
803 if (error != 0)
804 goto exec_fail_dealloc;
805 PROC_LOCK(p);
806 #ifdef MAC
807 if (will_transition) {
808 mac_vnode_execve_transition(oldcred, imgp->newcred,
809 imgp->vp, interpvplabel, imgp);
810 }
811 #endif
812 } else {
813 if (oldcred->cr_uid == oldcred->cr_ruid &&
814 oldcred->cr_gid == oldcred->cr_rgid)
815 p->p_flag &= ~P_SUGID;
816 }
817 /*
818 * Set the new credentials.
819 */
820 if (imgp->newcred != NULL) {
821 proc_set_cred(p, imgp->newcred);
822 crfree(oldcred);
823 oldcred = NULL;
824 }
825
826 /*
827 * Store the vp for use in procfs. This vnode was referenced by namei
828 * or fgetvp_exec.
829 */
830 oldtextvp = p->p_textvp;
831 p->p_textvp = newtextvp;
832
833 #ifdef KDTRACE_HOOKS
834 /*
835 * Tell the DTrace fasttrap provider about the exec if it
836 * has declared an interest.
837 */
838 if (dtrace_fasttrap_exec)
839 dtrace_fasttrap_exec(p);
840 #endif
841
842 /*
843 * Notify others that we exec'd, and clear the P_INEXEC flag
844 * as we're now a bona fide freshly-execed process.
845 */
846 KNOTE_LOCKED(p->p_klist, NOTE_EXEC);
847 p->p_flag &= ~P_INEXEC;
848
849 /* clear "fork but no exec" flag, as we _are_ execing */
850 p->p_acflag &= ~AFORK;
851
852 /*
853 * Free any previous argument cache and replace it with
854 * the new argument cache, if any.
855 */
856 oldargs = p->p_args;
857 p->p_args = newargs;
858 newargs = NULL;
859
860 PROC_UNLOCK(p);
861
862 #ifdef HWPMC_HOOKS
863 /*
864 * Check if system-wide sampling is in effect or if the
865 * current process is using PMCs. If so, do exec() time
866 * processing. This processing needs to happen AFTER the
867 * P_INEXEC flag is cleared.
868 */
869 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) {
870 VOP_UNLOCK(imgp->vp, 0);
871 pe.pm_credentialschanged = credential_changing;
872 pe.pm_entryaddr = imgp->entry_addr;
873
874 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe);
875 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
876 }
877 #endif
878
879 /* Set values passed into the program in registers. */
880 if (p->p_sysent->sv_setregs)
881 (*p->p_sysent->sv_setregs)(td, imgp,
882 (u_long)(uintptr_t)stack_base);
883 else
884 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base);
885
886 vfs_mark_atime(imgp->vp, td->td_ucred);
887
888 SDT_PROBE1(proc, , , exec__success, args->fname);
889
890 exec_fail_dealloc:
891 if (imgp->firstpage != NULL)
892 exec_unmap_first_page(imgp);
893
894 if (imgp->vp != NULL) {
895 if (args->fname)
896 NDFREE(&nd, NDF_ONLY_PNBUF);
897 if (imgp->opened)
898 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td);
899 if (error != 0)
900 vput(imgp->vp);
901 else
902 VOP_UNLOCK(imgp->vp, 0);
903 }
904
905 if (imgp->object != NULL)
906 vm_object_deallocate(imgp->object);
907
908 free(imgp->freepath, M_TEMP);
909
910 if (error == 0) {
911 if (p->p_ptevents & PTRACE_EXEC) {
912 PROC_LOCK(p);
913 if (p->p_ptevents & PTRACE_EXEC)
914 td->td_dbgflags |= TDB_EXEC;
915 PROC_UNLOCK(p);
916 }
917
918 /*
919 * Stop the process here if its stop event mask has
920 * the S_EXEC bit set.
921 */
922 STOPEVENT(p, S_EXEC, 0);
923 } else {
924 exec_fail:
925 /* we're done here, clear P_INEXEC */
926 PROC_LOCK(p);
927 p->p_flag &= ~P_INEXEC;
928 PROC_UNLOCK(p);
929
930 SDT_PROBE1(proc, , , exec__failure, error);
931 }
932
933 if (imgp->newcred != NULL && oldcred != NULL)
934 crfree(imgp->newcred);
935
936 #ifdef MAC
937 mac_execve_exit(imgp);
938 mac_execve_interpreter_exit(interpvplabel);
939 #endif
940 exec_free_args(args);
941
942 /*
943 * Handle deferred decrement of ref counts.
944 */
945 if (oldtextvp != NULL)
946 vrele(oldtextvp);
947 #ifdef KTRACE
948 if (tracevp != NULL)
949 vrele(tracevp);
950 if (tracecred != NULL)
951 crfree(tracecred);
952 #endif
953 pargs_drop(oldargs);
954 pargs_drop(newargs);
955 if (oldsigacts != NULL)
956 sigacts_free(oldsigacts);
957 if (euip != NULL)
958 uifree(euip);
959
960 if (error && imgp->vmspace_destroyed) {
961 /* sorry, no more process anymore. exit gracefully */
962 exit1(td, 0, SIGABRT);
963 /* NOT REACHED */
964 }
965
966 #ifdef KTRACE
967 if (error == 0)
968 ktrprocctor(p);
969 #endif
970
971 /*
972 * We don't want cpu_set_syscall_retval() to overwrite any of
973 * the register values put in place by exec_setregs().
974 * Implementations of cpu_set_syscall_retval() will leave
975 * registers unmodified when returning EJUSTRETURN.
976 */
977 return (error == 0 ? EJUSTRETURN : error);
978 }
979
980 int
981 exec_map_first_page(struct image_params *imgp)
982 {
983 int rv, i, after, initial_pagein;
984 vm_page_t ma[VM_INITIAL_PAGEIN];
985 vm_object_t object;
986
987 if (imgp->firstpage != NULL)
988 exec_unmap_first_page(imgp);
989
990 object = imgp->vp->v_object;
991 if (object == NULL)
992 return (EACCES);
993 VM_OBJECT_WLOCK(object);
994 #if VM_NRESERVLEVEL > 0
995 vm_object_color(object, 0);
996 #endif
997 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY);
998 if (ma[0]->valid != VM_PAGE_BITS_ALL) {
999 vm_page_xbusy(ma[0]);
1000 if (!vm_pager_has_page(object, 0, NULL, &after)) {
1001 vm_page_lock(ma[0]);
1002 vm_page_free(ma[0]);
1003 vm_page_unlock(ma[0]);
1004 VM_OBJECT_WUNLOCK(object);
1005 return (EIO);
1006 }
1007 initial_pagein = min(after, VM_INITIAL_PAGEIN);
1008 KASSERT(initial_pagein <= object->size,
1009 ("%s: initial_pagein %d object->size %ju",
1010 __func__, initial_pagein, (uintmax_t )object->size));
1011 for (i = 1; i < initial_pagein; i++) {
1012 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) {
1013 if (ma[i]->valid)
1014 break;
1015 if (!vm_page_tryxbusy(ma[i]))
1016 break;
1017 } else {
1018 ma[i] = vm_page_alloc(object, i,
1019 VM_ALLOC_NORMAL);
1020 if (ma[i] == NULL)
1021 break;
1022 }
1023 }
1024 initial_pagein = i;
1025 rv = vm_pager_get_pages(object, ma, initial_pagein, NULL, NULL);
1026 if (rv != VM_PAGER_OK) {
1027 for (i = 0; i < initial_pagein; i++) {
1028 vm_page_lock(ma[i]);
1029 vm_page_free(ma[i]);
1030 vm_page_unlock(ma[i]);
1031 }
1032 VM_OBJECT_WUNLOCK(object);
1033 return (EIO);
1034 }
1035 vm_page_xunbusy(ma[0]);
1036 for (i = 1; i < initial_pagein; i++)
1037 vm_page_readahead_finish(ma[i]);
1038 }
1039 vm_page_lock(ma[0]);
1040 vm_page_hold(ma[0]);
1041 vm_page_activate(ma[0]);
1042 vm_page_unlock(ma[0]);
1043 VM_OBJECT_WUNLOCK(object);
1044
1045 imgp->firstpage = sf_buf_alloc(ma[0], 0);
1046 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage);
1047
1048 return (0);
1049 }
1050
1051 void
1052 exec_unmap_first_page(struct image_params *imgp)
1053 {
1054 vm_page_t m;
1055
1056 if (imgp->firstpage != NULL) {
1057 m = sf_buf_page(imgp->firstpage);
1058 sf_buf_free(imgp->firstpage);
1059 imgp->firstpage = NULL;
1060 vm_page_lock(m);
1061 vm_page_unhold(m);
1062 vm_page_unlock(m);
1063 }
1064 }
1065
1066 /*
1067 * Destroy old address space, and allocate a new stack.
1068 * The new stack is only sgrowsiz large because it is grown
1069 * automatically on a page fault.
1070 */
1071 int
1072 exec_new_vmspace(struct image_params *imgp, struct sysentvec *sv)
1073 {
1074 int error;
1075 struct proc *p = imgp->proc;
1076 struct vmspace *vmspace = p->p_vmspace;
1077 vm_object_t obj;
1078 struct rlimit rlim_stack;
1079 vm_offset_t sv_minuser, stack_addr;
1080 vm_map_t map;
1081 u_long ssiz;
1082
1083 imgp->vmspace_destroyed = 1;
1084 imgp->sysent = sv;
1085
1086 /* May be called with Giant held */
1087 EVENTHANDLER_DIRECT_INVOKE(process_exec, p, imgp);
1088
1089 /*
1090 * Blow away entire process VM, if address space not shared,
1091 * otherwise, create a new VM space so that other threads are
1092 * not disrupted
1093 */
1094 map = &vmspace->vm_map;
1095 if (map_at_zero)
1096 sv_minuser = sv->sv_minuser;
1097 else
1098 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE);
1099 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser &&
1100 vm_map_max(map) == sv->sv_maxuser) {
1101 shmexit(vmspace);
1102 pmap_remove_pages(vmspace_pmap(vmspace));
1103 vm_map_remove(map, vm_map_min(map), vm_map_max(map));
1104 /* An exec terminates mlockall(MCL_FUTURE). */
1105 vm_map_lock(map);
1106 vm_map_modflags(map, 0, MAP_WIREFUTURE);
1107 vm_map_unlock(map);
1108 } else {
1109 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser);
1110 if (error)
1111 return (error);
1112 vmspace = p->p_vmspace;
1113 map = &vmspace->vm_map;
1114 }
1115
1116 /* Map a shared page */
1117 obj = sv->sv_shared_page_obj;
1118 if (obj != NULL) {
1119 vm_object_reference(obj);
1120 error = vm_map_fixed(map, obj, 0,
1121 sv->sv_shared_page_base, sv->sv_shared_page_len,
1122 VM_PROT_READ | VM_PROT_EXECUTE,
1123 VM_PROT_READ | VM_PROT_EXECUTE,
1124 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE);
1125 if (error != KERN_SUCCESS) {
1126 vm_object_deallocate(obj);
1127 return (vm_mmap_to_errno(error));
1128 }
1129 }
1130
1131 /* Allocate a new stack */
1132 if (imgp->stack_sz != 0) {
1133 ssiz = trunc_page(imgp->stack_sz);
1134 PROC_LOCK(p);
1135 lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack);
1136 PROC_UNLOCK(p);
1137 if (ssiz > rlim_stack.rlim_max)
1138 ssiz = rlim_stack.rlim_max;
1139 if (ssiz > rlim_stack.rlim_cur) {
1140 rlim_stack.rlim_cur = ssiz;
1141 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack);
1142 }
1143 } else if (sv->sv_maxssiz != NULL) {
1144 ssiz = *sv->sv_maxssiz;
1145 } else {
1146 ssiz = maxssiz;
1147 }
1148 stack_addr = sv->sv_usrstack - ssiz;
1149 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz,
1150 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot :
1151 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN);
1152 if (error != KERN_SUCCESS)
1153 return (vm_mmap_to_errno(error));
1154
1155 /*
1156 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they
1157 * are still used to enforce the stack rlimit on the process stack.
1158 */
1159 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT;
1160 vmspace->vm_maxsaddr = (char *)stack_addr;
1161
1162 return (0);
1163 }
1164
1165 /*
1166 * Copy out argument and environment strings from the old process address
1167 * space into the temporary string buffer.
1168 */
1169 int
1170 exec_copyin_args(struct image_args *args, char *fname,
1171 enum uio_seg segflg, char **argv, char **envv)
1172 {
1173 u_long argp, envp;
1174 int error;
1175 size_t length;
1176
1177 bzero(args, sizeof(*args));
1178 if (argv == NULL)
1179 return (EFAULT);
1180
1181 /*
1182 * Allocate demand-paged memory for the file name, argument, and
1183 * environment strings.
1184 */
1185 error = exec_alloc_args(args);
1186 if (error != 0)
1187 return (error);
1188
1189 /*
1190 * Copy the file name.
1191 */
1192 if (fname != NULL) {
1193 args->fname = args->buf;
1194 error = (segflg == UIO_SYSSPACE) ?
1195 copystr(fname, args->fname, PATH_MAX, &length) :
1196 copyinstr(fname, args->fname, PATH_MAX, &length);
1197 if (error != 0)
1198 goto err_exit;
1199 } else
1200 length = 0;
1201
1202 args->begin_argv = args->buf + length;
1203 args->endp = args->begin_argv;
1204 args->stringspace = ARG_MAX;
1205
1206 /*
1207 * extract arguments first
1208 */
1209 for (;;) {
1210 error = fueword(argv++, &argp);
1211 if (error == -1) {
1212 error = EFAULT;
1213 goto err_exit;
1214 }
1215 if (argp == 0)
1216 break;
1217 error = copyinstr((void *)(uintptr_t)argp, args->endp,
1218 args->stringspace, &length);
1219 if (error != 0) {
1220 if (error == ENAMETOOLONG)
1221 error = E2BIG;
1222 goto err_exit;
1223 }
1224 args->stringspace -= length;
1225 args->endp += length;
1226 args->argc++;
1227 }
1228
1229 args->begin_envv = args->endp;
1230
1231 /*
1232 * extract environment strings
1233 */
1234 if (envv) {
1235 for (;;) {
1236 error = fueword(envv++, &envp);
1237 if (error == -1) {
1238 error = EFAULT;
1239 goto err_exit;
1240 }
1241 if (envp == 0)
1242 break;
1243 error = copyinstr((void *)(uintptr_t)envp,
1244 args->endp, args->stringspace, &length);
1245 if (error != 0) {
1246 if (error == ENAMETOOLONG)
1247 error = E2BIG;
1248 goto err_exit;
1249 }
1250 args->stringspace -= length;
1251 args->endp += length;
1252 args->envc++;
1253 }
1254 }
1255
1256 return (0);
1257
1258 err_exit:
1259 exec_free_args(args);
1260 return (error);
1261 }
1262
1263 int
1264 exec_copyin_data_fds(struct thread *td, struct image_args *args,
1265 const void *data, size_t datalen, const int *fds, size_t fdslen)
1266 {
1267 struct filedesc *ofdp;
1268 const char *p;
1269 int *kfds;
1270 int error;
1271
1272 memset(args, '\0', sizeof(*args));
1273 ofdp = td->td_proc->p_fd;
1274 if (datalen >= ARG_MAX || fdslen > ofdp->fd_lastfile + 1)
1275 return (E2BIG);
1276 error = exec_alloc_args(args);
1277 if (error != 0)
1278 return (error);
1279
1280 args->begin_argv = args->buf;
1281 args->stringspace = ARG_MAX;
1282
1283 if (datalen > 0) {
1284 /*
1285 * Argument buffer has been provided. Copy it into the
1286 * kernel as a single string and add a terminating null
1287 * byte.
1288 */
1289 error = copyin(data, args->begin_argv, datalen);
1290 if (error != 0)
1291 goto err_exit;
1292 args->begin_argv[datalen] = '\0';
1293 args->endp = args->begin_argv + datalen + 1;
1294 args->stringspace -= datalen + 1;
1295
1296 /*
1297 * Traditional argument counting. Count the number of
1298 * null bytes.
1299 */
1300 for (p = args->begin_argv; p < args->endp; ++p)
1301 if (*p == '\0')
1302 ++args->argc;
1303 } else {
1304 /* No argument buffer provided. */
1305 args->endp = args->begin_argv;
1306 }
1307 /* There are no environment variables. */
1308 args->begin_envv = args->endp;
1309
1310 /* Create new file descriptor table. */
1311 kfds = malloc(fdslen * sizeof(int), M_TEMP, M_WAITOK);
1312 error = copyin(fds, kfds, fdslen * sizeof(int));
1313 if (error != 0) {
1314 free(kfds, M_TEMP);
1315 goto err_exit;
1316 }
1317 error = fdcopy_remapped(ofdp, kfds, fdslen, &args->fdp);
1318 free(kfds, M_TEMP);
1319 if (error != 0)
1320 goto err_exit;
1321
1322 return (0);
1323 err_exit:
1324 exec_free_args(args);
1325 return (error);
1326 }
1327
1328 struct exec_args_kva {
1329 vm_offset_t addr;
1330 u_int gen;
1331 SLIST_ENTRY(exec_args_kva) next;
1332 };
1333
1334 DPCPU_DEFINE_STATIC(struct exec_args_kva *, exec_args_kva);
1335
1336 static SLIST_HEAD(, exec_args_kva) exec_args_kva_freelist;
1337 static struct mtx exec_args_kva_mtx;
1338 static u_int exec_args_gen;
1339
1340 static void
1341 exec_prealloc_args_kva(void *arg __unused)
1342 {
1343 struct exec_args_kva *argkva;
1344 u_int i;
1345
1346 SLIST_INIT(&exec_args_kva_freelist);
1347 mtx_init(&exec_args_kva_mtx, "exec args kva", NULL, MTX_DEF);
1348 for (i = 0; i < exec_map_entries; i++) {
1349 argkva = malloc(sizeof(*argkva), M_PARGS, M_WAITOK);
1350 argkva->addr = kmap_alloc_wait(exec_map, exec_map_entry_size);
1351 argkva->gen = exec_args_gen;
1352 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next);
1353 }
1354 }
1355 SYSINIT(exec_args_kva, SI_SUB_EXEC, SI_ORDER_ANY, exec_prealloc_args_kva, NULL);
1356
1357 static vm_offset_t
1358 exec_alloc_args_kva(void **cookie)
1359 {
1360 struct exec_args_kva *argkva;
1361
1362 argkva = (void *)atomic_readandclear_ptr(
1363 (uintptr_t *)DPCPU_PTR(exec_args_kva));
1364 if (argkva == NULL) {
1365 mtx_lock(&exec_args_kva_mtx);
1366 while ((argkva = SLIST_FIRST(&exec_args_kva_freelist)) == NULL)
1367 (void)mtx_sleep(&exec_args_kva_freelist,
1368 &exec_args_kva_mtx, 0, "execkva", 0);
1369 SLIST_REMOVE_HEAD(&exec_args_kva_freelist, next);
1370 mtx_unlock(&exec_args_kva_mtx);
1371 }
1372 *(struct exec_args_kva **)cookie = argkva;
1373 return (argkva->addr);
1374 }
1375
1376 static void
1377 exec_release_args_kva(struct exec_args_kva *argkva, u_int gen)
1378 {
1379 vm_offset_t base;
1380
1381 base = argkva->addr;
1382 if (argkva->gen != gen) {
1383 (void)vm_map_madvise(exec_map, base, base + exec_map_entry_size,
1384 MADV_FREE);
1385 argkva->gen = gen;
1386 }
1387 if (!atomic_cmpset_ptr((uintptr_t *)DPCPU_PTR(exec_args_kva),
1388 (uintptr_t)NULL, (uintptr_t)argkva)) {
1389 mtx_lock(&exec_args_kva_mtx);
1390 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next);
1391 wakeup_one(&exec_args_kva_freelist);
1392 mtx_unlock(&exec_args_kva_mtx);
1393 }
1394 }
1395
1396 static void
1397 exec_free_args_kva(void *cookie)
1398 {
1399
1400 exec_release_args_kva(cookie, exec_args_gen);
1401 }
1402
1403 static void
1404 exec_args_kva_lowmem(void *arg __unused)
1405 {
1406 SLIST_HEAD(, exec_args_kva) head;
1407 struct exec_args_kva *argkva;
1408 u_int gen;
1409 int i;
1410
1411 gen = atomic_fetchadd_int(&exec_args_gen, 1) + 1;
1412
1413 /*
1414 * Force an madvise of each KVA range. Any currently allocated ranges
1415 * will have MADV_FREE applied once they are freed.
1416 */
1417 SLIST_INIT(&head);
1418 mtx_lock(&exec_args_kva_mtx);
1419 SLIST_SWAP(&head, &exec_args_kva_freelist, exec_args_kva);
1420 mtx_unlock(&exec_args_kva_mtx);
1421 while ((argkva = SLIST_FIRST(&head)) != NULL) {
1422 SLIST_REMOVE_HEAD(&head, next);
1423 exec_release_args_kva(argkva, gen);
1424 }
1425
1426 CPU_FOREACH(i) {
1427 argkva = (void *)atomic_readandclear_ptr(
1428 (uintptr_t *)DPCPU_ID_PTR(i, exec_args_kva));
1429 if (argkva != NULL)
1430 exec_release_args_kva(argkva, gen);
1431 }
1432 }
1433 EVENTHANDLER_DEFINE(vm_lowmem, exec_args_kva_lowmem, NULL,
1434 EVENTHANDLER_PRI_ANY);
1435
1436 /*
1437 * Allocate temporary demand-paged, zero-filled memory for the file name,
1438 * argument, and environment strings.
1439 */
1440 int
1441 exec_alloc_args(struct image_args *args)
1442 {
1443
1444 args->buf = (char *)exec_alloc_args_kva(&args->bufkva);
1445 return (0);
1446 }
1447
1448 void
1449 exec_free_args(struct image_args *args)
1450 {
1451
1452 if (args->buf != NULL) {
1453 exec_free_args_kva(args->bufkva);
1454 args->buf = NULL;
1455 }
1456 if (args->fname_buf != NULL) {
1457 free(args->fname_buf, M_TEMP);
1458 args->fname_buf = NULL;
1459 }
1460 if (args->fdp != NULL)
1461 fdescfree_remapped(args->fdp);
1462 }
1463
1464 /*
1465 * Copy strings out to the new process address space, constructing new arg
1466 * and env vector tables. Return a pointer to the base so that it can be used
1467 * as the initial stack pointer.
1468 */
1469 register_t *
1470 exec_copyout_strings(struct image_params *imgp)
1471 {
1472 int argc, envc;
1473 char **vectp;
1474 char *stringp;
1475 uintptr_t destp;
1476 register_t *stack_base;
1477 struct ps_strings *arginfo;
1478 struct proc *p;
1479 size_t execpath_len;
1480 int szsigcode, szps;
1481 char canary[sizeof(long) * 8];
1482
1483 szps = sizeof(pagesizes[0]) * MAXPAGESIZES;
1484 /*
1485 * Calculate string base and vector table pointers.
1486 * Also deal with signal trampoline code for this exec type.
1487 */
1488 if (imgp->execpath != NULL && imgp->auxargs != NULL)
1489 execpath_len = strlen(imgp->execpath) + 1;
1490 else
1491 execpath_len = 0;
1492 p = imgp->proc;
1493 szsigcode = 0;
1494 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings;
1495 if (p->p_sysent->sv_sigcode_base == 0) {
1496 if (p->p_sysent->sv_szsigcode != NULL)
1497 szsigcode = *(p->p_sysent->sv_szsigcode);
1498 }
1499 destp = (uintptr_t)arginfo;
1500
1501 /*
1502 * install sigcode
1503 */
1504 if (szsigcode != 0) {
1505 destp -= szsigcode;
1506 destp = rounddown2(destp, sizeof(void *));
1507 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode);
1508 }
1509
1510 /*
1511 * Copy the image path for the rtld.
1512 */
1513 if (execpath_len != 0) {
1514 destp -= execpath_len;
1515 destp = rounddown2(destp, sizeof(void *));
1516 imgp->execpathp = destp;
1517 copyout(imgp->execpath, (void *)destp, execpath_len);
1518 }
1519
1520 /*
1521 * Prepare the canary for SSP.
1522 */
1523 arc4rand(canary, sizeof(canary), 0);
1524 destp -= sizeof(canary);
1525 imgp->canary = destp;
1526 copyout(canary, (void *)destp, sizeof(canary));
1527 imgp->canarylen = sizeof(canary);
1528
1529 /*
1530 * Prepare the pagesizes array.
1531 */
1532 destp -= szps;
1533 destp = rounddown2(destp, sizeof(void *));
1534 imgp->pagesizes = destp;
1535 copyout(pagesizes, (void *)destp, szps);
1536 imgp->pagesizeslen = szps;
1537
1538 destp -= ARG_MAX - imgp->args->stringspace;
1539 destp = rounddown2(destp, sizeof(void *));
1540
1541 vectp = (char **)destp;
1542 if (imgp->auxargs) {
1543 /*
1544 * Allocate room on the stack for the ELF auxargs
1545 * array. It has up to AT_COUNT entries.
1546 */
1547 vectp -= howmany(AT_COUNT * sizeof(Elf_Auxinfo),
1548 sizeof(*vectp));
1549 }
1550
1551 /*
1552 * Allocate room for the argv[] and env vectors including the
1553 * terminating NULL pointers.
1554 */
1555 vectp -= imgp->args->argc + 1 + imgp->args->envc + 1;
1556
1557 /*
1558 * vectp also becomes our initial stack base
1559 */
1560 stack_base = (register_t *)vectp;
1561
1562 stringp = imgp->args->begin_argv;
1563 argc = imgp->args->argc;
1564 envc = imgp->args->envc;
1565
1566 /*
1567 * Copy out strings - arguments and environment.
1568 */
1569 copyout(stringp, (void *)destp, ARG_MAX - imgp->args->stringspace);
1570
1571 /*
1572 * Fill in "ps_strings" struct for ps, w, etc.
1573 */
1574 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp);
1575 suword32(&arginfo->ps_nargvstr, argc);
1576
1577 /*
1578 * Fill in argument portion of vector table.
1579 */
1580 for (; argc > 0; --argc) {
1581 suword(vectp++, (long)(intptr_t)destp);
1582 while (*stringp++ != 0)
1583 destp++;
1584 destp++;
1585 }
1586
1587 /* a null vector table pointer separates the argp's from the envp's */
1588 suword(vectp++, 0);
1589
1590 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp);
1591 suword32(&arginfo->ps_nenvstr, envc);
1592
1593 /*
1594 * Fill in environment portion of vector table.
1595 */
1596 for (; envc > 0; --envc) {
1597 suword(vectp++, (long)(intptr_t)destp);
1598 while (*stringp++ != 0)
1599 destp++;
1600 destp++;
1601 }
1602
1603 /* end of vector table is a null pointer */
1604 suword(vectp, 0);
1605
1606 return (stack_base);
1607 }
1608
1609 /*
1610 * Check permissions of file to execute.
1611 * Called with imgp->vp locked.
1612 * Return 0 for success or error code on failure.
1613 */
1614 int
1615 exec_check_permissions(struct image_params *imgp)
1616 {
1617 struct vnode *vp = imgp->vp;
1618 struct vattr *attr = imgp->attr;
1619 struct thread *td;
1620 int error, writecount;
1621
1622 td = curthread;
1623
1624 /* Get file attributes */
1625 error = VOP_GETATTR(vp, attr, td->td_ucred);
1626 if (error)
1627 return (error);
1628
1629 #ifdef MAC
1630 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp);
1631 if (error)
1632 return (error);
1633 #endif
1634
1635 /*
1636 * 1) Check if file execution is disabled for the filesystem that
1637 * this file resides on.
1638 * 2) Ensure that at least one execute bit is on. Otherwise, a
1639 * privileged user will always succeed, and we don't want this
1640 * to happen unless the file really is executable.
1641 * 3) Ensure that the file is a regular file.
1642 */
1643 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) ||
1644 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 ||
1645 (attr->va_type != VREG))
1646 return (EACCES);
1647
1648 /*
1649 * Zero length files can't be exec'd
1650 */
1651 if (attr->va_size == 0)
1652 return (ENOEXEC);
1653
1654 /*
1655 * Check for execute permission to file based on current credentials.
1656 */
1657 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td);
1658 if (error)
1659 return (error);
1660
1661 /*
1662 * Check number of open-for-writes on the file and deny execution
1663 * if there are any.
1664 */
1665 error = VOP_GET_WRITECOUNT(vp, &writecount);
1666 if (error != 0)
1667 return (error);
1668 if (writecount != 0)
1669 return (ETXTBSY);
1670
1671 /*
1672 * Call filesystem specific open routine (which does nothing in the
1673 * general case).
1674 */
1675 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL);
1676 if (error == 0)
1677 imgp->opened = 1;
1678 return (error);
1679 }
1680
1681 /*
1682 * Exec handler registration
1683 */
1684 int
1685 exec_register(const struct execsw *execsw_arg)
1686 {
1687 const struct execsw **es, **xs, **newexecsw;
1688 u_int count = 2; /* New slot and trailing NULL */
1689
1690 if (execsw)
1691 for (es = execsw; *es; es++)
1692 count++;
1693 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
1694 xs = newexecsw;
1695 if (execsw)
1696 for (es = execsw; *es; es++)
1697 *xs++ = *es;
1698 *xs++ = execsw_arg;
1699 *xs = NULL;
1700 if (execsw)
1701 free(execsw, M_TEMP);
1702 execsw = newexecsw;
1703 return (0);
1704 }
1705
1706 int
1707 exec_unregister(const struct execsw *execsw_arg)
1708 {
1709 const struct execsw **es, **xs, **newexecsw;
1710 int count = 1;
1711
1712 if (execsw == NULL)
1713 panic("unregister with no handlers left?\n");
1714
1715 for (es = execsw; *es; es++) {
1716 if (*es == execsw_arg)
1717 break;
1718 }
1719 if (*es == NULL)
1720 return (ENOENT);
1721 for (es = execsw; *es; es++)
1722 if (*es != execsw_arg)
1723 count++;
1724 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
1725 xs = newexecsw;
1726 for (es = execsw; *es; es++)
1727 if (*es != execsw_arg)
1728 *xs++ = *es;
1729 *xs = NULL;
1730 if (execsw)
1731 free(execsw, M_TEMP);
1732 execsw = newexecsw;
1733 return (0);
1734 }
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