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("$FreeBSD$");
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
sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)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
sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)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
sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS)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
sys_execve(struct thread * td,struct execve_args * uap)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 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td);
228 return (error);
229 }
230
231 #ifndef _SYS_SYSPROTO_H_
232 struct fexecve_args {
233 int fd;
234 char **argv;
235 char **envv;
236 }
237 #endif
238 int
sys_fexecve(struct thread * td,struct fexecve_args * uap)239 sys_fexecve(struct thread *td, struct fexecve_args *uap)
240 {
241 struct image_args args;
242 struct vmspace *oldvmspace;
243 int error;
244
245 error = pre_execve(td, &oldvmspace);
246 if (error != 0)
247 return (error);
248 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE,
249 uap->argv, uap->envv);
250 if (error == 0) {
251 args.fd = uap->fd;
252 error = kern_execve(td, &args, NULL);
253 }
254 post_execve(td, error, oldvmspace);
255 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td);
256 return (error);
257 }
258
259 #ifndef _SYS_SYSPROTO_H_
260 struct __mac_execve_args {
261 char *fname;
262 char **argv;
263 char **envv;
264 struct mac *mac_p;
265 };
266 #endif
267
268 int
sys___mac_execve(struct thread * td,struct __mac_execve_args * uap)269 sys___mac_execve(struct thread *td, struct __mac_execve_args *uap)
270 {
271 #ifdef MAC
272 struct image_args args;
273 struct vmspace *oldvmspace;
274 int error;
275
276 error = pre_execve(td, &oldvmspace);
277 if (error != 0)
278 return (error);
279 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
280 uap->argv, uap->envv);
281 if (error == 0)
282 error = kern_execve(td, &args, uap->mac_p);
283 post_execve(td, error, oldvmspace);
284 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td);
285 return (error);
286 #else
287 return (ENOSYS);
288 #endif
289 }
290
291 int
pre_execve(struct thread * td,struct vmspace ** oldvmspace)292 pre_execve(struct thread *td, struct vmspace **oldvmspace)
293 {
294 struct proc *p;
295 int error;
296
297 KASSERT(td == curthread, ("non-current thread %p", td));
298 error = 0;
299 p = td->td_proc;
300 if ((p->p_flag & P_HADTHREADS) != 0) {
301 PROC_LOCK(p);
302 if (thread_single(p, SINGLE_BOUNDARY) != 0)
303 error = ERESTART;
304 PROC_UNLOCK(p);
305 }
306 KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0,
307 ("nested execve"));
308 *oldvmspace = p->p_vmspace;
309 return (error);
310 }
311
312 void
post_execve(struct thread * td,int error,struct vmspace * oldvmspace)313 post_execve(struct thread *td, int error, struct vmspace *oldvmspace)
314 {
315 struct proc *p;
316
317 KASSERT(td == curthread, ("non-current thread %p", td));
318 p = td->td_proc;
319 if ((p->p_flag & P_HADTHREADS) != 0) {
320 PROC_LOCK(p);
321 /*
322 * If success, we upgrade to SINGLE_EXIT state to
323 * force other threads to suicide.
324 */
325 if (error == EJUSTRETURN)
326 thread_single(p, SINGLE_EXIT);
327 else
328 thread_single_end(p, SINGLE_BOUNDARY);
329 PROC_UNLOCK(p);
330 }
331 if ((td->td_pflags & TDP_EXECVMSPC) != 0) {
332 KASSERT(p->p_vmspace != oldvmspace,
333 ("oldvmspace still used"));
334 vmspace_free(oldvmspace);
335 td->td_pflags &= ~TDP_EXECVMSPC;
336 }
337 }
338
339 /*
340 * XXX: kern_execve has the astonishing property of not always returning to
341 * the caller. If sufficiently bad things happen during the call to
342 * do_execve(), it can end up calling exit1(); as a result, callers must
343 * avoid doing anything which they might need to undo (e.g., allocating
344 * memory).
345 */
346 int
kern_execve(struct thread * td,struct image_args * args,struct mac * mac_p)347 kern_execve(struct thread *td, struct image_args *args, struct mac *mac_p)
348 {
349
350 AUDIT_ARG_ARGV(args->begin_argv, args->argc,
351 args->begin_envv - args->begin_argv);
352 AUDIT_ARG_ENVV(args->begin_envv, args->envc,
353 args->endp - args->begin_envv);
354 return (do_execve(td, args, mac_p));
355 }
356
357 /*
358 * In-kernel implementation of execve(). All arguments are assumed to be
359 * userspace pointers from the passed thread.
360 */
361 static int
do_execve(struct thread * td,struct image_args * args,struct mac * mac_p)362 do_execve(struct thread *td, struct image_args *args, struct mac *mac_p)
363 {
364 struct proc *p = td->td_proc;
365 struct nameidata nd;
366 struct ucred *oldcred;
367 struct uidinfo *euip = NULL;
368 register_t *stack_base;
369 int error, i;
370 struct image_params image_params, *imgp;
371 struct vattr attr;
372 int (*img_first)(struct image_params *);
373 struct pargs *oldargs = NULL, *newargs = NULL;
374 struct sigacts *oldsigacts = NULL, *newsigacts = NULL;
375 #ifdef KTRACE
376 struct vnode *tracevp = NULL;
377 struct ucred *tracecred = NULL;
378 #endif
379 struct vnode *oldtextvp = NULL, *newtextvp;
380 int credential_changing;
381 #ifdef MAC
382 struct label *interpvplabel = NULL;
383 int will_transition;
384 #endif
385 #ifdef HWPMC_HOOKS
386 struct pmckern_procexec pe;
387 #endif
388 static const char fexecv_proc_title[] = "(fexecv)";
389
390 imgp = &image_params;
391
392 /*
393 * Lock the process and set the P_INEXEC flag to indicate that
394 * it should be left alone until we're done here. This is
395 * necessary to avoid race conditions - e.g. in ptrace() -
396 * that might allow a local user to illicitly obtain elevated
397 * privileges.
398 */
399 PROC_LOCK(p);
400 KASSERT((p->p_flag & P_INEXEC) == 0,
401 ("%s(): process already has P_INEXEC flag", __func__));
402 p->p_flag |= P_INEXEC;
403 PROC_UNLOCK(p);
404
405 /*
406 * Initialize part of the common data
407 */
408 bzero(imgp, sizeof(*imgp));
409 imgp->proc = p;
410 imgp->attr = &attr;
411 imgp->args = args;
412 oldcred = p->p_ucred;
413
414 #ifdef MAC
415 error = mac_execve_enter(imgp, mac_p);
416 if (error)
417 goto exec_fail;
418 #endif
419
420 /*
421 * Translate the file name. namei() returns a vnode pointer
422 * in ni_vp among other things.
423 *
424 * XXXAUDIT: It would be desirable to also audit the name of the
425 * interpreter if this is an interpreted binary.
426 */
427 if (args->fname != NULL) {
428 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | LOCKSHARED | FOLLOW |
429 SAVENAME | AUDITVNODE1, UIO_SYSSPACE, args->fname, td);
430 }
431
432 SDT_PROBE1(proc, , , exec, args->fname);
433
434 interpret:
435 if (args->fname != NULL) {
436 #ifdef CAPABILITY_MODE
437 /*
438 * While capability mode can't reach this point via direct
439 * path arguments to execve(), we also don't allow
440 * interpreters to be used in capability mode (for now).
441 * Catch indirect lookups and return a permissions error.
442 */
443 if (IN_CAPABILITY_MODE(td)) {
444 error = ECAPMODE;
445 goto exec_fail;
446 }
447 #endif
448 error = namei(&nd);
449 if (error)
450 goto exec_fail;
451
452 newtextvp = nd.ni_vp;
453 imgp->vp = newtextvp;
454 } else {
455 AUDIT_ARG_FD(args->fd);
456 /*
457 * Descriptors opened only with O_EXEC or O_RDONLY are allowed.
458 */
459 error = fgetvp_exec(td, args->fd, &cap_fexecve_rights, &newtextvp);
460 if (error)
461 goto exec_fail;
462 vn_lock(newtextvp, LK_SHARED | LK_RETRY);
463 AUDIT_ARG_VNODE1(newtextvp);
464 imgp->vp = newtextvp;
465 }
466
467 /*
468 * Check file permissions. Also 'opens' file and sets its vnode to
469 * text mode.
470 */
471 error = exec_check_permissions(imgp);
472 if (error)
473 goto exec_fail_dealloc;
474
475 imgp->object = imgp->vp->v_object;
476 if (imgp->object != NULL)
477 vm_object_reference(imgp->object);
478
479 error = exec_map_first_page(imgp);
480 if (error)
481 goto exec_fail_dealloc;
482
483 imgp->proc->p_osrel = 0;
484 imgp->proc->p_fctl0 = 0;
485
486 /*
487 * Implement image setuid/setgid.
488 *
489 * Determine new credentials before attempting image activators
490 * so that it can be used by process_exec handlers to determine
491 * credential/setid changes.
492 *
493 * Don't honor setuid/setgid if the filesystem prohibits it or if
494 * the process is being traced.
495 *
496 * We disable setuid/setgid/etc in capability mode on the basis
497 * that most setugid applications are not written with that
498 * environment in mind, and will therefore almost certainly operate
499 * incorrectly. In principle there's no reason that setugid
500 * applications might not be useful in capability mode, so we may want
501 * to reconsider this conservative design choice in the future.
502 *
503 * XXXMAC: For the time being, use NOSUID to also prohibit
504 * transitions on the file system.
505 */
506 credential_changing = 0;
507 credential_changing |= (attr.va_mode & S_ISUID) &&
508 oldcred->cr_uid != attr.va_uid;
509 credential_changing |= (attr.va_mode & S_ISGID) &&
510 oldcred->cr_gid != attr.va_gid;
511 #ifdef MAC
512 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp,
513 interpvplabel, imgp);
514 credential_changing |= will_transition;
515 #endif
516
517 /* Don't inherit PROC_PDEATHSIG_CTL value if setuid/setgid. */
518 if (credential_changing)
519 imgp->proc->p_pdeathsig = 0;
520
521 if (credential_changing &&
522 #ifdef CAPABILITY_MODE
523 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) &&
524 #endif
525 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 &&
526 (p->p_flag & P_TRACED) == 0) {
527 imgp->credential_setid = true;
528 VOP_UNLOCK(imgp->vp, 0);
529 imgp->newcred = crdup(oldcred);
530 if (attr.va_mode & S_ISUID) {
531 euip = uifind(attr.va_uid);
532 change_euid(imgp->newcred, euip);
533 }
534 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
535 if (attr.va_mode & S_ISGID)
536 change_egid(imgp->newcred, attr.va_gid);
537 /*
538 * Implement correct POSIX saved-id behavior.
539 *
540 * XXXMAC: Note that the current logic will save the
541 * uid and gid if a MAC domain transition occurs, even
542 * though maybe it shouldn't.
543 */
544 change_svuid(imgp->newcred, imgp->newcred->cr_uid);
545 change_svgid(imgp->newcred, imgp->newcred->cr_gid);
546 } else {
547 /*
548 * Implement correct POSIX saved-id behavior.
549 *
550 * XXX: It's not clear that the existing behavior is
551 * POSIX-compliant. A number of sources indicate that the
552 * saved uid/gid should only be updated if the new ruid is
553 * not equal to the old ruid, or the new euid is not equal
554 * to the old euid and the new euid is not equal to the old
555 * ruid. The FreeBSD code always updates the saved uid/gid.
556 * Also, this code uses the new (replaced) euid and egid as
557 * the source, which may or may not be the right ones to use.
558 */
559 if (oldcred->cr_svuid != oldcred->cr_uid ||
560 oldcred->cr_svgid != oldcred->cr_gid) {
561 VOP_UNLOCK(imgp->vp, 0);
562 imgp->newcred = crdup(oldcred);
563 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
564 change_svuid(imgp->newcred, imgp->newcred->cr_uid);
565 change_svgid(imgp->newcred, imgp->newcred->cr_gid);
566 }
567 }
568 /* The new credentials are installed into the process later. */
569
570 /*
571 * Do the best to calculate the full path to the image file.
572 */
573 if (args->fname != NULL && args->fname[0] == '/')
574 imgp->execpath = args->fname;
575 else {
576 VOP_UNLOCK(imgp->vp, 0);
577 if (vn_fullpath(td, imgp->vp, &imgp->execpath,
578 &imgp->freepath) != 0)
579 imgp->execpath = args->fname;
580 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
581 }
582
583 /*
584 * If the current process has a special image activator it
585 * wants to try first, call it. For example, emulating shell
586 * scripts differently.
587 */
588 error = -1;
589 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL)
590 error = img_first(imgp);
591
592 /*
593 * Loop through the list of image activators, calling each one.
594 * An activator returns -1 if there is no match, 0 on success,
595 * and an error otherwise.
596 */
597 for (i = 0; error == -1 && execsw[i]; ++i) {
598 if (execsw[i]->ex_imgact == NULL ||
599 execsw[i]->ex_imgact == img_first) {
600 continue;
601 }
602 error = (*execsw[i]->ex_imgact)(imgp);
603 }
604
605 if (error) {
606 if (error == -1)
607 error = ENOEXEC;
608 goto exec_fail_dealloc;
609 }
610
611 /*
612 * Special interpreter operation, cleanup and loop up to try to
613 * activate the interpreter.
614 */
615 if (imgp->interpreted) {
616 exec_unmap_first_page(imgp);
617 /*
618 * The text reference needs to be removed for scripts.
619 * There is a short period before we determine that
620 * something is a script where text reference is active.
621 * The vnode lock is held over this entire period
622 * so nothing should illegitimately be blocked.
623 */
624 MPASS(imgp->textset);
625 VOP_UNSET_TEXT_CHECKED(newtextvp);
626 imgp->textset = false;
627 /* free name buffer and old vnode */
628 if (args->fname != NULL)
629 NDFREE(&nd, NDF_ONLY_PNBUF);
630 #ifdef MAC
631 mac_execve_interpreter_enter(newtextvp, &interpvplabel);
632 #endif
633 if (imgp->opened) {
634 VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td);
635 imgp->opened = 0;
636 }
637 vput(newtextvp);
638 vm_object_deallocate(imgp->object);
639 imgp->object = NULL;
640 imgp->credential_setid = false;
641 if (imgp->newcred != NULL) {
642 crfree(imgp->newcred);
643 imgp->newcred = NULL;
644 }
645 imgp->execpath = NULL;
646 free(imgp->freepath, M_TEMP);
647 imgp->freepath = NULL;
648 /* set new name to that of the interpreter */
649 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME,
650 UIO_SYSSPACE, imgp->interpreter_name, td);
651 args->fname = imgp->interpreter_name;
652 goto interpret;
653 }
654
655 /*
656 * NB: We unlock the vnode here because it is believed that none
657 * of the sv_copyout_strings/sv_fixup operations require the vnode.
658 */
659 VOP_UNLOCK(imgp->vp, 0);
660
661 if (disallow_high_osrel &&
662 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) {
663 error = ENOEXEC;
664 uprintf("Osrel %d for image %s too high\n", p->p_osrel,
665 imgp->execpath != NULL ? imgp->execpath : "<unresolved>");
666 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
667 goto exec_fail_dealloc;
668 }
669
670 /* ABI enforces the use of Capsicum. Switch into capabilities mode. */
671 if (SV_PROC_FLAG(p, SV_CAPSICUM))
672 sys_cap_enter(td, NULL);
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 error = (*p->p_sysent->sv_fixup)(&stack_base, imgp);
689 else
690 error = suword(--stack_base, imgp->args->argc) == 0 ?
691 0 : EFAULT;
692 if (error != 0) {
693 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
694 goto exec_fail_dealloc;
695 }
696
697 if (args->fdp != NULL) {
698 /* Install a brand new file descriptor table. */
699 fdinstall_remapped(td, args->fdp);
700 args->fdp = NULL;
701 } else {
702 /*
703 * Keep on using the existing file descriptor table. For
704 * security and other reasons, the file descriptor table
705 * cannot be shared after an exec.
706 */
707 fdunshare(td);
708 /* close files on exec */
709 fdcloseexec(td);
710 }
711
712 /*
713 * Malloc things before we need locks.
714 */
715 i = imgp->args->begin_envv - imgp->args->begin_argv;
716 /* Cache arguments if they fit inside our allowance */
717 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) {
718 newargs = pargs_alloc(i);
719 bcopy(imgp->args->begin_argv, newargs->ar_args, i);
720 }
721
722 /*
723 * For security and other reasons, signal handlers cannot
724 * be shared after an exec. The new process gets a copy of the old
725 * handlers. In execsigs(), the new process will have its signals
726 * reset.
727 */
728 if (sigacts_shared(p->p_sigacts)) {
729 oldsigacts = p->p_sigacts;
730 newsigacts = sigacts_alloc();
731 sigacts_copy(newsigacts, oldsigacts);
732 }
733
734 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
735
736 PROC_LOCK(p);
737 if (oldsigacts)
738 p->p_sigacts = newsigacts;
739 /* Stop profiling */
740 stopprofclock(p);
741
742 /* reset caught signals */
743 execsigs(p);
744
745 /* name this process - nameiexec(p, ndp) */
746 bzero(p->p_comm, sizeof(p->p_comm));
747 if (args->fname)
748 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm,
749 min(nd.ni_cnd.cn_namelen, MAXCOMLEN));
750 else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0)
751 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title));
752 bcopy(p->p_comm, td->td_name, sizeof(td->td_name));
753 #ifdef KTR
754 sched_clear_tdname(td);
755 #endif
756
757 /*
758 * mark as execed, wakeup the process that vforked (if any) and tell
759 * it that it now has its own resources back
760 */
761 p->p_flag |= P_EXEC;
762 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0)
763 p->p_flag2 &= ~P2_NOTRACE;
764 if ((p->p_flag2 & P2_STKGAP_DISABLE_EXEC) == 0)
765 p->p_flag2 &= ~P2_STKGAP_DISABLE;
766 if (p->p_flag & P_PPWAIT) {
767 p->p_flag &= ~(P_PPWAIT | P_PPTRACE);
768 cv_broadcast(&p->p_pwait);
769 /* STOPs are no longer ignored, arrange for AST */
770 signotify(td);
771 }
772
773 /*
774 * Implement image setuid/setgid installation.
775 */
776 if (imgp->credential_setid) {
777 /*
778 * Turn off syscall tracing for set-id programs, except for
779 * root. Record any set-id flags first to make sure that
780 * we do not regain any tracing during a possible block.
781 */
782 setsugid(p);
783
784 #ifdef KTRACE
785 if (p->p_tracecred != NULL &&
786 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0))
787 ktrprocexec(p, &tracecred, &tracevp);
788 #endif
789 /*
790 * Close any file descriptors 0..2 that reference procfs,
791 * then make sure file descriptors 0..2 are in use.
792 *
793 * Both fdsetugidsafety() and fdcheckstd() may call functions
794 * taking sleepable locks, so temporarily drop our locks.
795 */
796 PROC_UNLOCK(p);
797 VOP_UNLOCK(imgp->vp, 0);
798 fdsetugidsafety(td);
799 error = fdcheckstd(td);
800 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
801 if (error != 0)
802 goto exec_fail_dealloc;
803 PROC_LOCK(p);
804 #ifdef MAC
805 if (will_transition) {
806 mac_vnode_execve_transition(oldcred, imgp->newcred,
807 imgp->vp, interpvplabel, imgp);
808 }
809 #endif
810 } else {
811 if (oldcred->cr_uid == oldcred->cr_ruid &&
812 oldcred->cr_gid == oldcred->cr_rgid)
813 p->p_flag &= ~P_SUGID;
814 }
815 /*
816 * Set the new credentials.
817 */
818 if (imgp->newcred != NULL) {
819 proc_set_cred(p, imgp->newcred);
820 crfree(oldcred);
821 oldcred = NULL;
822 }
823
824 /*
825 * Store the vp for use in procfs. This vnode was referenced by namei
826 * or fgetvp_exec.
827 */
828 oldtextvp = p->p_textvp;
829 p->p_textvp = newtextvp;
830
831 #ifdef KDTRACE_HOOKS
832 /*
833 * Tell the DTrace fasttrap provider about the exec if it
834 * has declared an interest.
835 */
836 if (dtrace_fasttrap_exec)
837 dtrace_fasttrap_exec(p);
838 #endif
839
840 /*
841 * Notify others that we exec'd, and clear the P_INEXEC flag
842 * as we're now a bona fide freshly-execed process.
843 */
844 KNOTE_LOCKED(p->p_klist, NOTE_EXEC);
845 p->p_flag &= ~P_INEXEC;
846
847 /* clear "fork but no exec" flag, as we _are_ execing */
848 p->p_acflag &= ~AFORK;
849
850 /*
851 * Free any previous argument cache and replace it with
852 * the new argument cache, if any.
853 */
854 oldargs = p->p_args;
855 p->p_args = newargs;
856 newargs = NULL;
857
858 PROC_UNLOCK(p);
859
860 #ifdef HWPMC_HOOKS
861 /*
862 * Check if system-wide sampling is in effect or if the
863 * current process is using PMCs. If so, do exec() time
864 * processing. This processing needs to happen AFTER the
865 * P_INEXEC flag is cleared.
866 */
867 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) {
868 VOP_UNLOCK(imgp->vp, 0);
869 pe.pm_credentialschanged = credential_changing;
870 pe.pm_entryaddr = imgp->entry_addr;
871
872 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe);
873 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
874 }
875 #endif
876
877 /* Set values passed into the program in registers. */
878 if (p->p_sysent->sv_setregs)
879 (*p->p_sysent->sv_setregs)(td, imgp,
880 (u_long)(uintptr_t)stack_base);
881 else
882 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base);
883
884 vfs_mark_atime(imgp->vp, td->td_ucred);
885
886 SDT_PROBE1(proc, , , exec__success, args->fname);
887
888 exec_fail_dealloc:
889 if (imgp->firstpage != NULL)
890 exec_unmap_first_page(imgp);
891
892 if (imgp->vp != NULL) {
893 if (args->fname)
894 NDFREE(&nd, NDF_ONLY_PNBUF);
895 if (imgp->opened)
896 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td);
897 if (imgp->textset)
898 VOP_UNSET_TEXT_CHECKED(imgp->vp);
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
exec_map_first_page(struct image_params * imgp)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
exec_unmap_first_page(struct image_params * imgp)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
exec_new_vmspace(struct image_params * imgp,struct sysentvec * sv)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 cpu_exec_vmspace_reuse(p, map)) {
1102 shmexit(vmspace);
1103 pmap_remove_pages(vmspace_pmap(vmspace));
1104 vm_map_remove(map, vm_map_min(map), vm_map_max(map));
1105 /*
1106 * An exec terminates mlockall(MCL_FUTURE), ASLR state
1107 * must be re-evaluated.
1108 */
1109 vm_map_lock(map);
1110 vm_map_modflags(map, 0, MAP_WIREFUTURE | MAP_ASLR |
1111 MAP_ASLR_IGNSTART);
1112 vm_map_unlock(map);
1113 } else {
1114 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser);
1115 if (error)
1116 return (error);
1117 vmspace = p->p_vmspace;
1118 map = &vmspace->vm_map;
1119 }
1120 map->flags |= imgp->map_flags;
1121
1122 /* Map a shared page */
1123 obj = sv->sv_shared_page_obj;
1124 if (obj != NULL) {
1125 vm_object_reference(obj);
1126 error = vm_map_fixed(map, obj, 0,
1127 sv->sv_shared_page_base, sv->sv_shared_page_len,
1128 VM_PROT_READ | VM_PROT_EXECUTE,
1129 VM_PROT_READ | VM_PROT_EXECUTE,
1130 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE);
1131 if (error != KERN_SUCCESS) {
1132 vm_object_deallocate(obj);
1133 return (vm_mmap_to_errno(error));
1134 }
1135 }
1136
1137 /* Allocate a new stack */
1138 if (imgp->stack_sz != 0) {
1139 ssiz = trunc_page(imgp->stack_sz);
1140 PROC_LOCK(p);
1141 lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack);
1142 PROC_UNLOCK(p);
1143 if (ssiz > rlim_stack.rlim_max)
1144 ssiz = rlim_stack.rlim_max;
1145 if (ssiz > rlim_stack.rlim_cur) {
1146 rlim_stack.rlim_cur = ssiz;
1147 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack);
1148 }
1149 } else if (sv->sv_maxssiz != NULL) {
1150 ssiz = *sv->sv_maxssiz;
1151 } else {
1152 ssiz = maxssiz;
1153 }
1154 imgp->eff_stack_sz = lim_cur(curthread, RLIMIT_STACK);
1155 if (ssiz < imgp->eff_stack_sz)
1156 imgp->eff_stack_sz = ssiz;
1157 stack_addr = sv->sv_usrstack - ssiz;
1158 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz,
1159 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot :
1160 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN);
1161 if (error != KERN_SUCCESS)
1162 return (vm_mmap_to_errno(error));
1163
1164 /*
1165 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they
1166 * are still used to enforce the stack rlimit on the process stack.
1167 */
1168 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT;
1169 vmspace->vm_maxsaddr = (char *)stack_addr;
1170
1171 return (0);
1172 }
1173
1174 /*
1175 * Copy out argument and environment strings from the old process address
1176 * space into the temporary string buffer.
1177 */
1178 int
exec_copyin_args(struct image_args * args,char * fname,enum uio_seg segflg,char ** argv,char ** envv)1179 exec_copyin_args(struct image_args *args, char *fname,
1180 enum uio_seg segflg, char **argv, char **envv)
1181 {
1182 u_long argp, envp;
1183 int error;
1184 size_t length;
1185
1186 bzero(args, sizeof(*args));
1187 if (argv == NULL)
1188 return (EFAULT);
1189
1190 /*
1191 * Allocate demand-paged memory for the file name, argument, and
1192 * environment strings.
1193 */
1194 error = exec_alloc_args(args);
1195 if (error != 0)
1196 return (error);
1197
1198 /*
1199 * Copy the file name.
1200 */
1201 if (fname != NULL) {
1202 args->fname = args->buf;
1203 error = (segflg == UIO_SYSSPACE) ?
1204 copystr(fname, args->fname, PATH_MAX, &length) :
1205 copyinstr(fname, args->fname, PATH_MAX, &length);
1206 if (error != 0)
1207 goto err_exit;
1208 } else
1209 length = 0;
1210
1211 args->begin_argv = args->buf + length;
1212 args->endp = args->begin_argv;
1213 args->stringspace = ARG_MAX;
1214
1215 /*
1216 * extract arguments first
1217 */
1218 for (;;) {
1219 error = fueword(argv++, &argp);
1220 if (error == -1) {
1221 error = EFAULT;
1222 goto err_exit;
1223 }
1224 if (argp == 0)
1225 break;
1226 error = copyinstr((void *)(uintptr_t)argp, args->endp,
1227 args->stringspace, &length);
1228 if (error != 0) {
1229 if (error == ENAMETOOLONG)
1230 error = E2BIG;
1231 goto err_exit;
1232 }
1233 args->stringspace -= length;
1234 args->endp += length;
1235 args->argc++;
1236 }
1237
1238 args->begin_envv = args->endp;
1239
1240 /*
1241 * extract environment strings
1242 */
1243 if (envv) {
1244 for (;;) {
1245 error = fueword(envv++, &envp);
1246 if (error == -1) {
1247 error = EFAULT;
1248 goto err_exit;
1249 }
1250 if (envp == 0)
1251 break;
1252 error = copyinstr((void *)(uintptr_t)envp,
1253 args->endp, args->stringspace, &length);
1254 if (error != 0) {
1255 if (error == ENAMETOOLONG)
1256 error = E2BIG;
1257 goto err_exit;
1258 }
1259 args->stringspace -= length;
1260 args->endp += length;
1261 args->envc++;
1262 }
1263 }
1264
1265 return (0);
1266
1267 err_exit:
1268 exec_free_args(args);
1269 return (error);
1270 }
1271
1272 int
exec_copyin_data_fds(struct thread * td,struct image_args * args,const void * data,size_t datalen,const int * fds,size_t fdslen)1273 exec_copyin_data_fds(struct thread *td, struct image_args *args,
1274 const void *data, size_t datalen, const int *fds, size_t fdslen)
1275 {
1276 struct filedesc *ofdp;
1277 const char *p;
1278 int *kfds;
1279 int error;
1280
1281 memset(args, '\0', sizeof(*args));
1282 ofdp = td->td_proc->p_fd;
1283 if (datalen >= ARG_MAX || fdslen > ofdp->fd_lastfile + 1)
1284 return (E2BIG);
1285 error = exec_alloc_args(args);
1286 if (error != 0)
1287 return (error);
1288
1289 args->begin_argv = args->buf;
1290 args->stringspace = ARG_MAX;
1291
1292 if (datalen > 0) {
1293 /*
1294 * Argument buffer has been provided. Copy it into the
1295 * kernel as a single string and add a terminating null
1296 * byte.
1297 */
1298 error = copyin(data, args->begin_argv, datalen);
1299 if (error != 0)
1300 goto err_exit;
1301 args->begin_argv[datalen] = '\0';
1302 args->endp = args->begin_argv + datalen + 1;
1303 args->stringspace -= datalen + 1;
1304
1305 /*
1306 * Traditional argument counting. Count the number of
1307 * null bytes.
1308 */
1309 for (p = args->begin_argv; p < args->endp; ++p)
1310 if (*p == '\0')
1311 ++args->argc;
1312 } else {
1313 /* No argument buffer provided. */
1314 args->endp = args->begin_argv;
1315 }
1316 /* There are no environment variables. */
1317 args->begin_envv = args->endp;
1318
1319 /* Create new file descriptor table. */
1320 kfds = malloc(fdslen * sizeof(int), M_TEMP, M_WAITOK);
1321 error = copyin(fds, kfds, fdslen * sizeof(int));
1322 if (error != 0) {
1323 free(kfds, M_TEMP);
1324 goto err_exit;
1325 }
1326 error = fdcopy_remapped(ofdp, kfds, fdslen, &args->fdp);
1327 free(kfds, M_TEMP);
1328 if (error != 0)
1329 goto err_exit;
1330
1331 return (0);
1332 err_exit:
1333 exec_free_args(args);
1334 return (error);
1335 }
1336
1337 struct exec_args_kva {
1338 vm_offset_t addr;
1339 u_int gen;
1340 SLIST_ENTRY(exec_args_kva) next;
1341 };
1342
1343 DPCPU_DEFINE_STATIC(struct exec_args_kva *, exec_args_kva);
1344
1345 static SLIST_HEAD(, exec_args_kva) exec_args_kva_freelist;
1346 static struct mtx exec_args_kva_mtx;
1347 static u_int exec_args_gen;
1348
1349 static void
exec_prealloc_args_kva(void * arg __unused)1350 exec_prealloc_args_kva(void *arg __unused)
1351 {
1352 struct exec_args_kva *argkva;
1353 u_int i;
1354
1355 SLIST_INIT(&exec_args_kva_freelist);
1356 mtx_init(&exec_args_kva_mtx, "exec args kva", NULL, MTX_DEF);
1357 for (i = 0; i < exec_map_entries; i++) {
1358 argkva = malloc(sizeof(*argkva), M_PARGS, M_WAITOK);
1359 argkva->addr = kmap_alloc_wait(exec_map, exec_map_entry_size);
1360 argkva->gen = exec_args_gen;
1361 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next);
1362 }
1363 }
1364 SYSINIT(exec_args_kva, SI_SUB_EXEC, SI_ORDER_ANY, exec_prealloc_args_kva, NULL);
1365
1366 static vm_offset_t
exec_alloc_args_kva(void ** cookie)1367 exec_alloc_args_kva(void **cookie)
1368 {
1369 struct exec_args_kva *argkva;
1370
1371 argkva = (void *)atomic_readandclear_ptr(
1372 (uintptr_t *)DPCPU_PTR(exec_args_kva));
1373 if (argkva == NULL) {
1374 mtx_lock(&exec_args_kva_mtx);
1375 while ((argkva = SLIST_FIRST(&exec_args_kva_freelist)) == NULL)
1376 (void)mtx_sleep(&exec_args_kva_freelist,
1377 &exec_args_kva_mtx, 0, "execkva", 0);
1378 SLIST_REMOVE_HEAD(&exec_args_kva_freelist, next);
1379 mtx_unlock(&exec_args_kva_mtx);
1380 }
1381 *(struct exec_args_kva **)cookie = argkva;
1382 return (argkva->addr);
1383 }
1384
1385 static void
exec_release_args_kva(struct exec_args_kva * argkva,u_int gen)1386 exec_release_args_kva(struct exec_args_kva *argkva, u_int gen)
1387 {
1388 vm_offset_t base;
1389
1390 base = argkva->addr;
1391 if (argkva->gen != gen) {
1392 (void)vm_map_madvise(exec_map, base, base + exec_map_entry_size,
1393 MADV_FREE);
1394 argkva->gen = gen;
1395 }
1396 if (!atomic_cmpset_ptr((uintptr_t *)DPCPU_PTR(exec_args_kva),
1397 (uintptr_t)NULL, (uintptr_t)argkva)) {
1398 mtx_lock(&exec_args_kva_mtx);
1399 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next);
1400 wakeup_one(&exec_args_kva_freelist);
1401 mtx_unlock(&exec_args_kva_mtx);
1402 }
1403 }
1404
1405 static void
exec_free_args_kva(void * cookie)1406 exec_free_args_kva(void *cookie)
1407 {
1408
1409 exec_release_args_kva(cookie, exec_args_gen);
1410 }
1411
1412 static void
exec_args_kva_lowmem(void * arg __unused)1413 exec_args_kva_lowmem(void *arg __unused)
1414 {
1415 SLIST_HEAD(, exec_args_kva) head;
1416 struct exec_args_kva *argkva;
1417 u_int gen;
1418 int i;
1419
1420 gen = atomic_fetchadd_int(&exec_args_gen, 1) + 1;
1421
1422 /*
1423 * Force an madvise of each KVA range. Any currently allocated ranges
1424 * will have MADV_FREE applied once they are freed.
1425 */
1426 SLIST_INIT(&head);
1427 mtx_lock(&exec_args_kva_mtx);
1428 SLIST_SWAP(&head, &exec_args_kva_freelist, exec_args_kva);
1429 mtx_unlock(&exec_args_kva_mtx);
1430 while ((argkva = SLIST_FIRST(&head)) != NULL) {
1431 SLIST_REMOVE_HEAD(&head, next);
1432 exec_release_args_kva(argkva, gen);
1433 }
1434
1435 CPU_FOREACH(i) {
1436 argkva = (void *)atomic_readandclear_ptr(
1437 (uintptr_t *)DPCPU_ID_PTR(i, exec_args_kva));
1438 if (argkva != NULL)
1439 exec_release_args_kva(argkva, gen);
1440 }
1441 }
1442 EVENTHANDLER_DEFINE(vm_lowmem, exec_args_kva_lowmem, NULL,
1443 EVENTHANDLER_PRI_ANY);
1444
1445 /*
1446 * Allocate temporary demand-paged, zero-filled memory for the file name,
1447 * argument, and environment strings.
1448 */
1449 int
exec_alloc_args(struct image_args * args)1450 exec_alloc_args(struct image_args *args)
1451 {
1452
1453 args->buf = (char *)exec_alloc_args_kva(&args->bufkva);
1454 return (0);
1455 }
1456
1457 void
exec_free_args(struct image_args * args)1458 exec_free_args(struct image_args *args)
1459 {
1460
1461 if (args->buf != NULL) {
1462 exec_free_args_kva(args->bufkva);
1463 args->buf = NULL;
1464 }
1465 if (args->fname_buf != NULL) {
1466 free(args->fname_buf, M_TEMP);
1467 args->fname_buf = NULL;
1468 }
1469 if (args->fdp != NULL)
1470 fdescfree_remapped(args->fdp);
1471 }
1472
1473 /*
1474 * Copy strings out to the new process address space, constructing new arg
1475 * and env vector tables. Return a pointer to the base so that it can be used
1476 * as the initial stack pointer.
1477 */
1478 register_t *
exec_copyout_strings(struct image_params * imgp)1479 exec_copyout_strings(struct image_params *imgp)
1480 {
1481 int argc, envc;
1482 char **vectp;
1483 char *stringp;
1484 uintptr_t destp;
1485 register_t *stack_base;
1486 struct ps_strings *arginfo;
1487 struct proc *p;
1488 size_t execpath_len;
1489 int szsigcode, szps;
1490 char canary[sizeof(long) * 8];
1491
1492 szps = sizeof(pagesizes[0]) * MAXPAGESIZES;
1493 /*
1494 * Calculate string base and vector table pointers.
1495 * Also deal with signal trampoline code for this exec type.
1496 */
1497 if (imgp->execpath != NULL && imgp->auxargs != NULL)
1498 execpath_len = strlen(imgp->execpath) + 1;
1499 else
1500 execpath_len = 0;
1501 p = imgp->proc;
1502 szsigcode = 0;
1503 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings;
1504 if (p->p_sysent->sv_sigcode_base == 0) {
1505 if (p->p_sysent->sv_szsigcode != NULL)
1506 szsigcode = *(p->p_sysent->sv_szsigcode);
1507 }
1508 destp = (uintptr_t)arginfo;
1509
1510 /*
1511 * install sigcode
1512 */
1513 if (szsigcode != 0) {
1514 destp -= szsigcode;
1515 destp = rounddown2(destp, sizeof(void *));
1516 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode);
1517 }
1518
1519 /*
1520 * Copy the image path for the rtld.
1521 */
1522 if (execpath_len != 0) {
1523 destp -= execpath_len;
1524 destp = rounddown2(destp, sizeof(void *));
1525 imgp->execpathp = destp;
1526 copyout(imgp->execpath, (void *)destp, execpath_len);
1527 }
1528
1529 /*
1530 * Prepare the canary for SSP.
1531 */
1532 arc4rand(canary, sizeof(canary), 0);
1533 destp -= sizeof(canary);
1534 imgp->canary = destp;
1535 copyout(canary, (void *)destp, sizeof(canary));
1536 imgp->canarylen = sizeof(canary);
1537
1538 /*
1539 * Prepare the pagesizes array.
1540 */
1541 destp -= szps;
1542 destp = rounddown2(destp, sizeof(void *));
1543 imgp->pagesizes = destp;
1544 copyout(pagesizes, (void *)destp, szps);
1545 imgp->pagesizeslen = szps;
1546
1547 destp -= ARG_MAX - imgp->args->stringspace;
1548 destp = rounddown2(destp, sizeof(void *));
1549
1550 vectp = (char **)destp;
1551 if (imgp->sysent->sv_stackgap != NULL)
1552 imgp->sysent->sv_stackgap(imgp, (u_long *)&vectp);
1553
1554 if (imgp->auxargs) {
1555 /*
1556 * Allocate room on the stack for the ELF auxargs
1557 * array. It has up to AT_COUNT entries.
1558 */
1559 vectp -= howmany(AT_COUNT * sizeof(Elf_Auxinfo),
1560 sizeof(*vectp));
1561 }
1562
1563 /*
1564 * Allocate room for the argv[] and env vectors including the
1565 * terminating NULL pointers.
1566 */
1567 vectp -= imgp->args->argc + 1 + imgp->args->envc + 1;
1568
1569 /*
1570 * vectp also becomes our initial stack base
1571 */
1572 stack_base = (register_t *)vectp;
1573
1574 stringp = imgp->args->begin_argv;
1575 argc = imgp->args->argc;
1576 envc = imgp->args->envc;
1577
1578 /*
1579 * Copy out strings - arguments and environment.
1580 */
1581 copyout(stringp, (void *)destp, ARG_MAX - imgp->args->stringspace);
1582
1583 /*
1584 * Fill in "ps_strings" struct for ps, w, etc.
1585 */
1586 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp);
1587 suword32(&arginfo->ps_nargvstr, argc);
1588
1589 /*
1590 * Fill in argument portion of vector table.
1591 */
1592 for (; argc > 0; --argc) {
1593 suword(vectp++, (long)(intptr_t)destp);
1594 while (*stringp++ != 0)
1595 destp++;
1596 destp++;
1597 }
1598
1599 /* a null vector table pointer separates the argp's from the envp's */
1600 suword(vectp++, 0);
1601
1602 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp);
1603 suword32(&arginfo->ps_nenvstr, envc);
1604
1605 /*
1606 * Fill in environment portion of vector table.
1607 */
1608 for (; envc > 0; --envc) {
1609 suword(vectp++, (long)(intptr_t)destp);
1610 while (*stringp++ != 0)
1611 destp++;
1612 destp++;
1613 }
1614
1615 /* end of vector table is a null pointer */
1616 suword(vectp, 0);
1617
1618 return (stack_base);
1619 }
1620
1621 /*
1622 * Check permissions of file to execute.
1623 * Called with imgp->vp locked.
1624 * Return 0 for success or error code on failure.
1625 */
1626 int
exec_check_permissions(struct image_params * imgp)1627 exec_check_permissions(struct image_params *imgp)
1628 {
1629 struct vnode *vp = imgp->vp;
1630 struct vattr *attr = imgp->attr;
1631 struct thread *td;
1632 int error;
1633
1634 td = curthread;
1635
1636 /* Get file attributes */
1637 error = VOP_GETATTR(vp, attr, td->td_ucred);
1638 if (error)
1639 return (error);
1640
1641 #ifdef MAC
1642 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp);
1643 if (error)
1644 return (error);
1645 #endif
1646
1647 /*
1648 * 1) Check if file execution is disabled for the filesystem that
1649 * this file resides on.
1650 * 2) Ensure that at least one execute bit is on. Otherwise, a
1651 * privileged user will always succeed, and we don't want this
1652 * to happen unless the file really is executable.
1653 * 3) Ensure that the file is a regular file.
1654 */
1655 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) ||
1656 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 ||
1657 (attr->va_type != VREG))
1658 return (EACCES);
1659
1660 /*
1661 * Zero length files can't be exec'd
1662 */
1663 if (attr->va_size == 0)
1664 return (ENOEXEC);
1665
1666 /*
1667 * Check for execute permission to file based on current credentials.
1668 */
1669 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td);
1670 if (error)
1671 return (error);
1672
1673 /*
1674 * Check number of open-for-writes on the file and deny execution
1675 * if there are any.
1676 *
1677 * Add a text reference now so no one can write to the
1678 * executable while we're activating it.
1679 *
1680 * Remember if this was set before and unset it in case this is not
1681 * actually an executable image.
1682 */
1683 error = VOP_SET_TEXT(vp);
1684 if (error != 0)
1685 return (error);
1686 imgp->textset = true;
1687
1688 /*
1689 * Call filesystem specific open routine (which does nothing in the
1690 * general case).
1691 */
1692 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL);
1693 if (error == 0)
1694 imgp->opened = 1;
1695 return (error);
1696 }
1697
1698 /*
1699 * Exec handler registration
1700 */
1701 int
exec_register(const struct execsw * execsw_arg)1702 exec_register(const struct execsw *execsw_arg)
1703 {
1704 const struct execsw **es, **xs, **newexecsw;
1705 u_int count = 2; /* New slot and trailing NULL */
1706
1707 if (execsw)
1708 for (es = execsw; *es; es++)
1709 count++;
1710 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
1711 xs = newexecsw;
1712 if (execsw)
1713 for (es = execsw; *es; es++)
1714 *xs++ = *es;
1715 *xs++ = execsw_arg;
1716 *xs = NULL;
1717 if (execsw)
1718 free(execsw, M_TEMP);
1719 execsw = newexecsw;
1720 return (0);
1721 }
1722
1723 int
exec_unregister(const struct execsw * execsw_arg)1724 exec_unregister(const struct execsw *execsw_arg)
1725 {
1726 const struct execsw **es, **xs, **newexecsw;
1727 int count = 1;
1728
1729 if (execsw == NULL)
1730 panic("unregister with no handlers left?\n");
1731
1732 for (es = execsw; *es; es++) {
1733 if (*es == execsw_arg)
1734 break;
1735 }
1736 if (*es == NULL)
1737 return (ENOENT);
1738 for (es = execsw; *es; es++)
1739 if (*es != execsw_arg)
1740 count++;
1741 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
1742 xs = newexecsw;
1743 for (es = execsw; *es; es++)
1744 if (*es != execsw_arg)
1745 *xs++ = *es;
1746 *xs = NULL;
1747 if (execsw)
1748 free(execsw, M_TEMP);
1749 execsw = newexecsw;
1750 return (0);
1751 }
1752