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/asan.h>
41 #include <sys/capsicum.h>
42 #include <sys/eventhandler.h>
43 #include <sys/exec.h>
44 #include <sys/fcntl.h>
45 #include <sys/filedesc.h>
46 #include <sys/imgact.h>
47 #include <sys/imgact_elf.h>
48 #include <sys/kernel.h>
49 #include <sys/lock.h>
50 #include <sys/malloc.h>
51 #include <sys/mman.h>
52 #include <sys/mount.h>
53 #include <sys/mutex.h>
54 #include <sys/namei.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/timers.h>
72 #include <sys/umtx.h>
73 #include <sys/vnode.h>
74 #include <sys/wait.h>
75 #ifdef KTRACE
76 #include <sys/ktrace.h>
77 #endif
78
79 #include <vm/vm.h>
80 #include <vm/vm_param.h>
81 #include <vm/pmap.h>
82 #include <vm/vm_page.h>
83 #include <vm/vm_map.h>
84 #include <vm/vm_kern.h>
85 #include <vm/vm_extern.h>
86 #include <vm/vm_object.h>
87 #include <vm/vm_pager.h>
88
89 #ifdef HWPMC_HOOKS
90 #include <sys/pmckern.h>
91 #endif
92
93 #include <machine/reg.h>
94
95 #include <security/audit/audit.h>
96 #include <security/mac/mac_framework.h>
97
98 #ifdef KDTRACE_HOOKS
99 #include <sys/dtrace_bsd.h>
100 dtrace_execexit_func_t dtrace_fasttrap_exec;
101 #endif
102
103 SDT_PROVIDER_DECLARE(proc);
104 SDT_PROBE_DEFINE1(proc, , , exec, "char *");
105 SDT_PROBE_DEFINE1(proc, , , exec__failure, "int");
106 SDT_PROBE_DEFINE1(proc, , , exec__success, "char *");
107
108 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments");
109
110 int coredump_pack_fileinfo = 1;
111 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_fileinfo, CTLFLAG_RWTUN,
112 &coredump_pack_fileinfo, 0,
113 "Enable file path packing in 'procstat -f' coredump notes");
114
115 int coredump_pack_vmmapinfo = 1;
116 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_vmmapinfo, CTLFLAG_RWTUN,
117 &coredump_pack_vmmapinfo, 0,
118 "Enable file path packing in 'procstat -v' coredump notes");
119
120 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS);
121 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS);
122 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS);
123 static int do_execve(struct thread *td, struct image_args *args,
124 struct mac *mac_p, struct vmspace *oldvmspace);
125
126 /* XXX This should be vm_size_t. */
127 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD|
128 CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_ps_strings, "LU",
129 "Location of process' ps_strings structure");
130
131 /* XXX This should be vm_size_t. */
132 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD|
133 CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_usrstack, "LU",
134 "Top of process stack");
135
136 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD|CTLFLAG_MPSAFE,
137 NULL, 0, sysctl_kern_stackprot, "I",
138 "Stack memory permissions");
139
140 u_long ps_arg_cache_limit = PAGE_SIZE / 16;
141 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW,
142 &ps_arg_cache_limit, 0,
143 "Process' command line characters cache limit");
144
145 static int disallow_high_osrel;
146 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW,
147 &disallow_high_osrel, 0,
148 "Disallow execution of binaries built for higher version of the world");
149
150 static int map_at_zero = 0;
151 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RWTUN, &map_at_zero, 0,
152 "Permit processes to map an object at virtual address 0.");
153
154 int core_dump_can_intr = 1;
155 SYSCTL_INT(_kern, OID_AUTO, core_dump_can_intr, CTLFLAG_RWTUN,
156 &core_dump_can_intr, 0,
157 "Core dumping interruptible with SIGKILL");
158
159 static int
sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)160 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)
161 {
162 struct proc *p;
163 vm_offset_t ps_strings;
164
165 p = curproc;
166 #ifdef SCTL_MASK32
167 if (req->flags & SCTL_MASK32) {
168 unsigned int val;
169 val = (unsigned int)PROC_PS_STRINGS(p);
170 return (SYSCTL_OUT(req, &val, sizeof(val)));
171 }
172 #endif
173 ps_strings = PROC_PS_STRINGS(p);
174 return (SYSCTL_OUT(req, &ps_strings, sizeof(ps_strings)));
175 }
176
177 static int
sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)178 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)
179 {
180 struct proc *p;
181 vm_offset_t val;
182
183 p = curproc;
184 #ifdef SCTL_MASK32
185 if (req->flags & SCTL_MASK32) {
186 unsigned int val32;
187
188 val32 = round_page((unsigned int)p->p_vmspace->vm_stacktop);
189 return (SYSCTL_OUT(req, &val32, sizeof(val32)));
190 }
191 #endif
192 val = round_page(p->p_vmspace->vm_stacktop);
193 return (SYSCTL_OUT(req, &val, sizeof(val)));
194 }
195
196 static int
sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS)197 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS)
198 {
199 struct proc *p;
200
201 p = curproc;
202 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot,
203 sizeof(p->p_sysent->sv_stackprot)));
204 }
205
206 /*
207 * Each of the items is a pointer to a `const struct execsw', hence the
208 * double pointer here.
209 */
210 static const struct execsw **execsw;
211
212 #ifndef _SYS_SYSPROTO_H_
213 struct execve_args {
214 char *fname;
215 char **argv;
216 char **envv;
217 };
218 #endif
219
220 int
sys_execve(struct thread * td,struct execve_args * uap)221 sys_execve(struct thread *td, struct execve_args *uap)
222 {
223 struct image_args args;
224 struct vmspace *oldvmspace;
225 int error;
226
227 error = pre_execve(td, &oldvmspace);
228 if (error != 0)
229 return (error);
230 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
231 uap->argv, uap->envv);
232 if (error == 0)
233 error = kern_execve(td, &args, NULL, oldvmspace);
234 post_execve(td, error, oldvmspace);
235 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td);
236 return (error);
237 }
238
239 #ifndef _SYS_SYSPROTO_H_
240 struct fexecve_args {
241 int fd;
242 char **argv;
243 char **envv;
244 };
245 #endif
246 int
sys_fexecve(struct thread * td,struct fexecve_args * uap)247 sys_fexecve(struct thread *td, struct fexecve_args *uap)
248 {
249 struct image_args args;
250 struct vmspace *oldvmspace;
251 int error;
252
253 error = pre_execve(td, &oldvmspace);
254 if (error != 0)
255 return (error);
256 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE,
257 uap->argv, uap->envv);
258 if (error == 0) {
259 args.fd = uap->fd;
260 error = kern_execve(td, &args, NULL, oldvmspace);
261 }
262 post_execve(td, error, oldvmspace);
263 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td);
264 return (error);
265 }
266
267 #ifndef _SYS_SYSPROTO_H_
268 struct __mac_execve_args {
269 char *fname;
270 char **argv;
271 char **envv;
272 struct mac *mac_p;
273 };
274 #endif
275
276 int
sys___mac_execve(struct thread * td,struct __mac_execve_args * uap)277 sys___mac_execve(struct thread *td, struct __mac_execve_args *uap)
278 {
279 #ifdef MAC
280 struct image_args args;
281 struct vmspace *oldvmspace;
282 int error;
283
284 error = pre_execve(td, &oldvmspace);
285 if (error != 0)
286 return (error);
287 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE,
288 uap->argv, uap->envv);
289 if (error == 0)
290 error = kern_execve(td, &args, uap->mac_p, oldvmspace);
291 post_execve(td, error, oldvmspace);
292 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td);
293 return (error);
294 #else
295 return (ENOSYS);
296 #endif
297 }
298
299 int
pre_execve(struct thread * td,struct vmspace ** oldvmspace)300 pre_execve(struct thread *td, struct vmspace **oldvmspace)
301 {
302 struct proc *p;
303 int error;
304
305 KASSERT(td == curthread, ("non-current thread %p", td));
306 error = 0;
307 p = td->td_proc;
308 if ((p->p_flag & P_HADTHREADS) != 0) {
309 PROC_LOCK(p);
310 if (thread_single(p, SINGLE_BOUNDARY) != 0)
311 error = ERESTART;
312 PROC_UNLOCK(p);
313 }
314 KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0,
315 ("nested execve"));
316 *oldvmspace = p->p_vmspace;
317 return (error);
318 }
319
320 void
post_execve(struct thread * td,int error,struct vmspace * oldvmspace)321 post_execve(struct thread *td, int error, struct vmspace *oldvmspace)
322 {
323 struct proc *p;
324
325 KASSERT(td == curthread, ("non-current thread %p", td));
326 p = td->td_proc;
327 if ((p->p_flag & P_HADTHREADS) != 0) {
328 PROC_LOCK(p);
329 /*
330 * If success, we upgrade to SINGLE_EXIT state to
331 * force other threads to suicide.
332 */
333 if (error == EJUSTRETURN)
334 thread_single(p, SINGLE_EXIT);
335 else
336 thread_single_end(p, SINGLE_BOUNDARY);
337 PROC_UNLOCK(p);
338 }
339 exec_cleanup(td, oldvmspace);
340 }
341
342 /*
343 * kern_execve() has the astonishing property of not always returning to
344 * the caller. If sufficiently bad things happen during the call to
345 * do_execve(), it can end up calling exit1(); as a result, callers must
346 * avoid doing anything which they might need to undo (e.g., allocating
347 * memory).
348 */
349 int
kern_execve(struct thread * td,struct image_args * args,struct mac * mac_p,struct vmspace * oldvmspace)350 kern_execve(struct thread *td, struct image_args *args, struct mac *mac_p,
351 struct vmspace *oldvmspace)
352 {
353
354 TSEXEC(td->td_proc->p_pid, args->begin_argv);
355 AUDIT_ARG_ARGV(args->begin_argv, args->argc,
356 exec_args_get_begin_envv(args) - args->begin_argv);
357 AUDIT_ARG_ENVV(exec_args_get_begin_envv(args), args->envc,
358 args->endp - exec_args_get_begin_envv(args));
359
360 /* Must have at least one argument. */
361 if (args->argc == 0) {
362 exec_free_args(args);
363 return (EINVAL);
364 }
365 return (do_execve(td, args, mac_p, oldvmspace));
366 }
367
368 static void
execve_nosetid(struct image_params * imgp)369 execve_nosetid(struct image_params *imgp)
370 {
371 imgp->credential_setid = false;
372 if (imgp->newcred != NULL) {
373 crfree(imgp->newcred);
374 imgp->newcred = NULL;
375 }
376 }
377
378 /*
379 * In-kernel implementation of execve(). All arguments are assumed to be
380 * userspace pointers from the passed thread.
381 */
382 static int
do_execve(struct thread * td,struct image_args * args,struct mac * mac_p,struct vmspace * oldvmspace)383 do_execve(struct thread *td, struct image_args *args, struct mac *mac_p,
384 struct vmspace *oldvmspace)
385 {
386 struct proc *p = td->td_proc;
387 struct nameidata nd;
388 struct ucred *oldcred;
389 struct uidinfo *euip = NULL;
390 uintptr_t stack_base;
391 struct image_params image_params, *imgp;
392 struct vattr attr;
393 int (*img_first)(struct image_params *);
394 struct pargs *oldargs = NULL, *newargs = NULL;
395 struct sigacts *oldsigacts = NULL, *newsigacts = NULL;
396 #ifdef KTRACE
397 struct ktr_io_params *kiop;
398 #endif
399 struct vnode *oldtextvp, *newtextvp;
400 struct vnode *oldtextdvp, *newtextdvp;
401 char *oldbinname, *newbinname;
402 bool credential_changing;
403 #ifdef MAC
404 struct label *interpvplabel = NULL;
405 bool will_transition;
406 #endif
407 #ifdef HWPMC_HOOKS
408 struct pmckern_procexec pe;
409 #endif
410 int error, i, orig_osrel;
411 uint32_t orig_fctl0;
412 size_t freepath_size;
413 static const char fexecv_proc_title[] = "(fexecv)";
414
415 imgp = &image_params;
416 oldtextvp = oldtextdvp = NULL;
417 newtextvp = newtextdvp = NULL;
418 newbinname = oldbinname = NULL;
419 #ifdef KTRACE
420 kiop = NULL;
421 #endif
422
423 /*
424 * Lock the process and set the P_INEXEC flag to indicate that
425 * it should be left alone until we're done here. This is
426 * necessary to avoid race conditions - e.g. in ptrace() -
427 * that might allow a local user to illicitly obtain elevated
428 * privileges.
429 */
430 PROC_LOCK(p);
431 KASSERT((p->p_flag & P_INEXEC) == 0,
432 ("%s(): process already has P_INEXEC flag", __func__));
433 p->p_flag |= P_INEXEC;
434 PROC_UNLOCK(p);
435
436 /*
437 * Initialize part of the common data
438 */
439 bzero(imgp, sizeof(*imgp));
440 imgp->proc = p;
441 imgp->attr = &attr;
442 imgp->args = args;
443 oldcred = p->p_ucred;
444 orig_osrel = p->p_osrel;
445 orig_fctl0 = p->p_fctl0;
446
447 #ifdef MAC
448 error = mac_execve_enter(imgp, mac_p);
449 if (error)
450 goto exec_fail;
451 #endif
452
453 SDT_PROBE1(proc, , , exec, args->fname);
454
455 interpret:
456 if (args->fname != NULL) {
457 #ifdef CAPABILITY_MODE
458 /*
459 * While capability mode can't reach this point via direct
460 * path arguments to execve(), we also don't allow
461 * interpreters to be used in capability mode (for now).
462 * Catch indirect lookups and return a permissions error.
463 */
464 if (IN_CAPABILITY_MODE(td)) {
465 error = ECAPMODE;
466 goto exec_fail;
467 }
468 #endif
469
470 /*
471 * Translate the file name. namei() returns a vnode
472 * pointer in ni_vp among other things.
473 */
474 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | LOCKSHARED | FOLLOW |
475 SAVENAME | AUDITVNODE1 | WANTPARENT, UIO_SYSSPACE,
476 args->fname, td);
477
478 error = namei(&nd);
479 if (error)
480 goto exec_fail;
481
482 newtextvp = nd.ni_vp;
483 newtextdvp = nd.ni_dvp;
484 nd.ni_dvp = NULL;
485 newbinname = malloc(nd.ni_cnd.cn_namelen + 1, M_PARGS,
486 M_WAITOK);
487 memcpy(newbinname, nd.ni_cnd.cn_nameptr, nd.ni_cnd.cn_namelen);
488 newbinname[nd.ni_cnd.cn_namelen] = '\0';
489 imgp->vp = newtextvp;
490
491 /*
492 * Do the best to calculate the full path to the image file.
493 */
494 if (args->fname[0] == '/') {
495 imgp->execpath = args->fname;
496 } else {
497 VOP_UNLOCK(imgp->vp);
498 freepath_size = MAXPATHLEN;
499 if (vn_fullpath_hardlink(newtextvp, newtextdvp,
500 newbinname, nd.ni_cnd.cn_namelen, &imgp->execpath,
501 &imgp->freepath, &freepath_size) != 0)
502 imgp->execpath = args->fname;
503 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
504 }
505 } else {
506 AUDIT_ARG_FD(args->fd);
507
508 /*
509 * If the descriptors was not opened with O_PATH, then
510 * we require that it was opened with O_EXEC or
511 * O_RDONLY. In either case, exec_check_permissions()
512 * below checks _current_ file access mode regardless
513 * of the permissions additionally checked at the
514 * open(2).
515 */
516 error = fgetvp_exec(td, args->fd, &cap_fexecve_rights,
517 &newtextvp);
518 if (error != 0)
519 goto exec_fail;
520
521 if (vn_fullpath(newtextvp, &imgp->execpath,
522 &imgp->freepath) != 0)
523 imgp->execpath = args->fname;
524 vn_lock(newtextvp, LK_SHARED | LK_RETRY);
525 AUDIT_ARG_VNODE1(newtextvp);
526 imgp->vp = newtextvp;
527 }
528
529 /*
530 * Check file permissions. Also 'opens' file and sets its vnode to
531 * text mode.
532 */
533 error = exec_check_permissions(imgp);
534 if (error)
535 goto exec_fail_dealloc;
536
537 imgp->object = imgp->vp->v_object;
538 if (imgp->object != NULL)
539 vm_object_reference(imgp->object);
540
541 error = exec_map_first_page(imgp);
542 if (error)
543 goto exec_fail_dealloc;
544
545 imgp->proc->p_osrel = 0;
546 imgp->proc->p_fctl0 = 0;
547
548 /*
549 * Implement image setuid/setgid.
550 *
551 * Determine new credentials before attempting image activators
552 * so that it can be used by process_exec handlers to determine
553 * credential/setid changes.
554 *
555 * Don't honor setuid/setgid if the filesystem prohibits it or if
556 * the process is being traced.
557 *
558 * We disable setuid/setgid/etc in capability mode on the basis
559 * that most setugid applications are not written with that
560 * environment in mind, and will therefore almost certainly operate
561 * incorrectly. In principle there's no reason that setugid
562 * applications might not be useful in capability mode, so we may want
563 * to reconsider this conservative design choice in the future.
564 *
565 * XXXMAC: For the time being, use NOSUID to also prohibit
566 * transitions on the file system.
567 */
568 credential_changing = false;
569 credential_changing |= (attr.va_mode & S_ISUID) &&
570 oldcred->cr_uid != attr.va_uid;
571 credential_changing |= (attr.va_mode & S_ISGID) &&
572 oldcred->cr_gid != attr.va_gid;
573 #ifdef MAC
574 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp,
575 interpvplabel, imgp) != 0;
576 credential_changing |= will_transition;
577 #endif
578
579 /* Don't inherit PROC_PDEATHSIG_CTL value if setuid/setgid. */
580 if (credential_changing)
581 imgp->proc->p_pdeathsig = 0;
582
583 if (credential_changing &&
584 #ifdef CAPABILITY_MODE
585 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) &&
586 #endif
587 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 &&
588 (p->p_flag & P_TRACED) == 0) {
589 imgp->credential_setid = true;
590 VOP_UNLOCK(imgp->vp);
591 imgp->newcred = crdup(oldcred);
592 if (attr.va_mode & S_ISUID) {
593 euip = uifind(attr.va_uid);
594 change_euid(imgp->newcred, euip);
595 }
596 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
597 if (attr.va_mode & S_ISGID)
598 change_egid(imgp->newcred, attr.va_gid);
599 /*
600 * Implement correct POSIX saved-id behavior.
601 *
602 * XXXMAC: Note that the current logic will save the
603 * uid and gid if a MAC domain transition occurs, even
604 * though maybe it shouldn't.
605 */
606 change_svuid(imgp->newcred, imgp->newcred->cr_uid);
607 change_svgid(imgp->newcred, imgp->newcred->cr_gid);
608 } else {
609 /*
610 * Implement correct POSIX saved-id behavior.
611 *
612 * XXX: It's not clear that the existing behavior is
613 * POSIX-compliant. A number of sources indicate that the
614 * saved uid/gid should only be updated if the new ruid is
615 * not equal to the old ruid, or the new euid is not equal
616 * to the old euid and the new euid is not equal to the old
617 * ruid. The FreeBSD code always updates the saved uid/gid.
618 * Also, this code uses the new (replaced) euid and egid as
619 * the source, which may or may not be the right ones to use.
620 */
621 if (oldcred->cr_svuid != oldcred->cr_uid ||
622 oldcred->cr_svgid != oldcred->cr_gid) {
623 VOP_UNLOCK(imgp->vp);
624 imgp->newcred = crdup(oldcred);
625 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
626 change_svuid(imgp->newcred, imgp->newcred->cr_uid);
627 change_svgid(imgp->newcred, imgp->newcred->cr_gid);
628 }
629 }
630 /* The new credentials are installed into the process later. */
631
632 /*
633 * If the current process has a special image activator it
634 * wants to try first, call it. For example, emulating shell
635 * scripts differently.
636 */
637 error = -1;
638 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL)
639 error = img_first(imgp);
640
641 /*
642 * Loop through the list of image activators, calling each one.
643 * An activator returns -1 if there is no match, 0 on success,
644 * and an error otherwise.
645 */
646 for (i = 0; error == -1 && execsw[i]; ++i) {
647 if (execsw[i]->ex_imgact == NULL ||
648 execsw[i]->ex_imgact == img_first) {
649 continue;
650 }
651 error = (*execsw[i]->ex_imgact)(imgp);
652 }
653
654 if (error) {
655 if (error == -1)
656 error = ENOEXEC;
657 goto exec_fail_dealloc;
658 }
659
660 /*
661 * Special interpreter operation, cleanup and loop up to try to
662 * activate the interpreter.
663 */
664 if (imgp->interpreted) {
665 exec_unmap_first_page(imgp);
666 /*
667 * The text reference needs to be removed for scripts.
668 * There is a short period before we determine that
669 * something is a script where text reference is active.
670 * The vnode lock is held over this entire period
671 * so nothing should illegitimately be blocked.
672 */
673 MPASS(imgp->textset);
674 VOP_UNSET_TEXT_CHECKED(newtextvp);
675 imgp->textset = false;
676 /* free name buffer and old vnode */
677 #ifdef MAC
678 mac_execve_interpreter_enter(newtextvp, &interpvplabel);
679 #endif
680 if (imgp->opened) {
681 VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td);
682 imgp->opened = false;
683 }
684 vput(newtextvp);
685 imgp->vp = newtextvp = NULL;
686 if (args->fname != NULL) {
687 if (newtextdvp != NULL) {
688 vrele(newtextdvp);
689 newtextdvp = NULL;
690 }
691 NDFREE(&nd, NDF_ONLY_PNBUF);
692 free(newbinname, M_PARGS);
693 newbinname = NULL;
694 }
695 vm_object_deallocate(imgp->object);
696 imgp->object = NULL;
697 execve_nosetid(imgp);
698 imgp->execpath = NULL;
699 free(imgp->freepath, M_TEMP);
700 imgp->freepath = NULL;
701 /* set new name to that of the interpreter */
702 args->fname = imgp->interpreter_name;
703 goto interpret;
704 }
705
706 /*
707 * NB: We unlock the vnode here because it is believed that none
708 * of the sv_copyout_strings/sv_fixup operations require the vnode.
709 */
710 VOP_UNLOCK(imgp->vp);
711
712 if (disallow_high_osrel &&
713 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) {
714 error = ENOEXEC;
715 uprintf("Osrel %d for image %s too high\n", p->p_osrel,
716 imgp->execpath != NULL ? imgp->execpath : "<unresolved>");
717 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
718 goto exec_fail_dealloc;
719 }
720
721 /* ABI enforces the use of Capsicum. Switch into capabilities mode. */
722 if (SV_PROC_FLAG(p, SV_CAPSICUM))
723 sys_cap_enter(td, NULL);
724
725 /*
726 * Copy out strings (args and env) and initialize stack base.
727 */
728 error = (*p->p_sysent->sv_copyout_strings)(imgp, &stack_base);
729 if (error != 0) {
730 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
731 goto exec_fail_dealloc;
732 }
733
734 /*
735 * Stack setup.
736 */
737 error = (*p->p_sysent->sv_fixup)(&stack_base, imgp);
738 if (error != 0) {
739 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
740 goto exec_fail_dealloc;
741 }
742
743 if (args->fdp != NULL) {
744 /* Install a brand new file descriptor table. */
745 fdinstall_remapped(td, args->fdp);
746 args->fdp = NULL;
747 } else {
748 /*
749 * Keep on using the existing file descriptor table. For
750 * security and other reasons, the file descriptor table
751 * cannot be shared after an exec.
752 */
753 fdunshare(td);
754 pdunshare(td);
755 /* close files on exec */
756 fdcloseexec(td);
757 }
758
759 /*
760 * Malloc things before we need locks.
761 */
762 i = exec_args_get_begin_envv(imgp->args) - imgp->args->begin_argv;
763 /* Cache arguments if they fit inside our allowance */
764 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) {
765 newargs = pargs_alloc(i);
766 bcopy(imgp->args->begin_argv, newargs->ar_args, i);
767 }
768
769 /*
770 * For security and other reasons, signal handlers cannot
771 * be shared after an exec. The new process gets a copy of the old
772 * handlers. In execsigs(), the new process will have its signals
773 * reset.
774 */
775 if (sigacts_shared(p->p_sigacts)) {
776 oldsigacts = p->p_sigacts;
777 newsigacts = sigacts_alloc();
778 sigacts_copy(newsigacts, oldsigacts);
779 }
780
781 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
782
783 PROC_LOCK(p);
784 if (oldsigacts)
785 p->p_sigacts = newsigacts;
786 /* Stop profiling */
787 stopprofclock(p);
788
789 /* reset caught signals */
790 execsigs(p);
791
792 /* name this process - nameiexec(p, ndp) */
793 bzero(p->p_comm, sizeof(p->p_comm));
794 if (args->fname)
795 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm,
796 min(nd.ni_cnd.cn_namelen, MAXCOMLEN));
797 else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0)
798 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title));
799 bcopy(p->p_comm, td->td_name, sizeof(td->td_name));
800 #ifdef KTR
801 sched_clear_tdname(td);
802 #endif
803
804 /*
805 * mark as execed, wakeup the process that vforked (if any) and tell
806 * it that it now has its own resources back
807 */
808 p->p_flag |= P_EXEC;
809 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0)
810 p->p_flag2 &= ~P2_NOTRACE;
811 if ((p->p_flag2 & P2_STKGAP_DISABLE_EXEC) == 0)
812 p->p_flag2 &= ~P2_STKGAP_DISABLE;
813 if (p->p_flag & P_PPWAIT) {
814 p->p_flag &= ~(P_PPWAIT | P_PPTRACE);
815 cv_broadcast(&p->p_pwait);
816 /* STOPs are no longer ignored, arrange for AST */
817 signotify(td);
818 }
819
820 if ((imgp->sysent->sv_setid_allowed != NULL &&
821 !(*imgp->sysent->sv_setid_allowed)(td, imgp)) ||
822 (p->p_flag2 & P2_NO_NEW_PRIVS) != 0)
823 execve_nosetid(imgp);
824
825 /*
826 * Implement image setuid/setgid installation.
827 */
828 if (imgp->credential_setid) {
829 /*
830 * Turn off syscall tracing for set-id programs, except for
831 * root. Record any set-id flags first to make sure that
832 * we do not regain any tracing during a possible block.
833 */
834 setsugid(p);
835 #ifdef KTRACE
836 kiop = ktrprocexec(p);
837 #endif
838 /*
839 * Close any file descriptors 0..2 that reference procfs,
840 * then make sure file descriptors 0..2 are in use.
841 *
842 * Both fdsetugidsafety() and fdcheckstd() may call functions
843 * taking sleepable locks, so temporarily drop our locks.
844 */
845 PROC_UNLOCK(p);
846 VOP_UNLOCK(imgp->vp);
847 fdsetugidsafety(td);
848 error = fdcheckstd(td);
849 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
850 if (error != 0)
851 goto exec_fail_dealloc;
852 PROC_LOCK(p);
853 #ifdef MAC
854 if (will_transition) {
855 mac_vnode_execve_transition(oldcred, imgp->newcred,
856 imgp->vp, interpvplabel, imgp);
857 }
858 #endif
859 } else {
860 if (oldcred->cr_uid == oldcred->cr_ruid &&
861 oldcred->cr_gid == oldcred->cr_rgid)
862 p->p_flag &= ~P_SUGID;
863 }
864 /*
865 * Set the new credentials.
866 */
867 if (imgp->newcred != NULL) {
868 proc_set_cred(p, imgp->newcred);
869 crfree(oldcred);
870 oldcred = NULL;
871 }
872
873 /*
874 * Store the vp for use in kern.proc.pathname. This vnode was
875 * referenced by namei() or by fexecve variant of fname handling.
876 */
877 oldtextvp = p->p_textvp;
878 p->p_textvp = newtextvp;
879 oldtextdvp = p->p_textdvp;
880 p->p_textdvp = newtextdvp;
881 newtextdvp = NULL;
882 oldbinname = p->p_binname;
883 p->p_binname = newbinname;
884 newbinname = NULL;
885
886 #ifdef KDTRACE_HOOKS
887 /*
888 * Tell the DTrace fasttrap provider about the exec if it
889 * has declared an interest.
890 */
891 if (dtrace_fasttrap_exec)
892 dtrace_fasttrap_exec(p);
893 #endif
894
895 /*
896 * Notify others that we exec'd, and clear the P_INEXEC flag
897 * as we're now a bona fide freshly-execed process.
898 */
899 KNOTE_LOCKED(p->p_klist, NOTE_EXEC);
900 p->p_flag &= ~P_INEXEC;
901
902 /* clear "fork but no exec" flag, as we _are_ execing */
903 p->p_acflag &= ~AFORK;
904
905 /*
906 * Free any previous argument cache and replace it with
907 * the new argument cache, if any.
908 */
909 oldargs = p->p_args;
910 p->p_args = newargs;
911 newargs = NULL;
912
913 PROC_UNLOCK(p);
914
915 #ifdef HWPMC_HOOKS
916 /*
917 * Check if system-wide sampling is in effect or if the
918 * current process is using PMCs. If so, do exec() time
919 * processing. This processing needs to happen AFTER the
920 * P_INEXEC flag is cleared.
921 */
922 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) {
923 VOP_UNLOCK(imgp->vp);
924 pe.pm_credentialschanged = credential_changing;
925 pe.pm_entryaddr = imgp->entry_addr;
926
927 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe);
928 vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
929 }
930 #endif
931
932 /* Set values passed into the program in registers. */
933 (*p->p_sysent->sv_setregs)(td, imgp, stack_base);
934
935 VOP_MMAPPED(imgp->vp);
936
937 SDT_PROBE1(proc, , , exec__success, args->fname);
938
939 exec_fail_dealloc:
940 if (error != 0) {
941 p->p_osrel = orig_osrel;
942 p->p_fctl0 = orig_fctl0;
943 }
944
945 if (imgp->firstpage != NULL)
946 exec_unmap_first_page(imgp);
947
948 if (imgp->vp != NULL) {
949 if (imgp->opened)
950 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td);
951 if (imgp->textset)
952 VOP_UNSET_TEXT_CHECKED(imgp->vp);
953 if (error != 0)
954 vput(imgp->vp);
955 else
956 VOP_UNLOCK(imgp->vp);
957 if (args->fname != NULL)
958 NDFREE(&nd, NDF_ONLY_PNBUF);
959 if (newtextdvp != NULL)
960 vrele(newtextdvp);
961 free(newbinname, M_PARGS);
962 }
963
964 if (imgp->object != NULL)
965 vm_object_deallocate(imgp->object);
966
967 free(imgp->freepath, M_TEMP);
968
969 if (error == 0) {
970 if (p->p_ptevents & PTRACE_EXEC) {
971 PROC_LOCK(p);
972 if (p->p_ptevents & PTRACE_EXEC)
973 td->td_dbgflags |= TDB_EXEC;
974 PROC_UNLOCK(p);
975 }
976 } else {
977 exec_fail:
978 /* we're done here, clear P_INEXEC */
979 PROC_LOCK(p);
980 p->p_flag &= ~P_INEXEC;
981 PROC_UNLOCK(p);
982
983 SDT_PROBE1(proc, , , exec__failure, error);
984 }
985
986 if (imgp->newcred != NULL && oldcred != NULL)
987 crfree(imgp->newcred);
988
989 #ifdef MAC
990 mac_execve_exit(imgp);
991 mac_execve_interpreter_exit(interpvplabel);
992 #endif
993 exec_free_args(args);
994
995 /*
996 * Handle deferred decrement of ref counts.
997 */
998 if (oldtextvp != NULL)
999 vrele(oldtextvp);
1000 if (oldtextdvp != NULL)
1001 vrele(oldtextdvp);
1002 free(oldbinname, M_PARGS);
1003 #ifdef KTRACE
1004 ktr_io_params_free(kiop);
1005 #endif
1006 pargs_drop(oldargs);
1007 pargs_drop(newargs);
1008 if (oldsigacts != NULL)
1009 sigacts_free(oldsigacts);
1010 if (euip != NULL)
1011 uifree(euip);
1012
1013 if (error && imgp->vmspace_destroyed) {
1014 /* sorry, no more process anymore. exit gracefully */
1015 exec_cleanup(td, oldvmspace);
1016 exit1(td, 0, SIGABRT);
1017 /* NOT REACHED */
1018 }
1019
1020 #ifdef KTRACE
1021 if (error == 0)
1022 ktrprocctor(p);
1023 #endif
1024
1025 /*
1026 * We don't want cpu_set_syscall_retval() to overwrite any of
1027 * the register values put in place by exec_setregs().
1028 * Implementations of cpu_set_syscall_retval() will leave
1029 * registers unmodified when returning EJUSTRETURN.
1030 */
1031 return (error == 0 ? EJUSTRETURN : error);
1032 }
1033
1034 void
exec_cleanup(struct thread * td,struct vmspace * oldvmspace)1035 exec_cleanup(struct thread *td, struct vmspace *oldvmspace)
1036 {
1037 if ((td->td_pflags & TDP_EXECVMSPC) != 0) {
1038 KASSERT(td->td_proc->p_vmspace != oldvmspace,
1039 ("oldvmspace still used"));
1040 vmspace_free(oldvmspace);
1041 td->td_pflags &= ~TDP_EXECVMSPC;
1042 }
1043 }
1044
1045 int
exec_map_first_page(struct image_params * imgp)1046 exec_map_first_page(struct image_params *imgp)
1047 {
1048 vm_object_t object;
1049 vm_page_t m;
1050 int error;
1051
1052 if (imgp->firstpage != NULL)
1053 exec_unmap_first_page(imgp);
1054
1055 object = imgp->vp->v_object;
1056 if (object == NULL)
1057 return (EACCES);
1058 #if VM_NRESERVLEVEL > 0
1059 if ((object->flags & OBJ_COLORED) == 0) {
1060 VM_OBJECT_WLOCK(object);
1061 vm_object_color(object, 0);
1062 VM_OBJECT_WUNLOCK(object);
1063 }
1064 #endif
1065 error = vm_page_grab_valid_unlocked(&m, object, 0,
1066 VM_ALLOC_COUNT(VM_INITIAL_PAGEIN) |
1067 VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY | VM_ALLOC_WIRED);
1068
1069 if (error != VM_PAGER_OK)
1070 return (EIO);
1071 imgp->firstpage = sf_buf_alloc(m, 0);
1072 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage);
1073
1074 return (0);
1075 }
1076
1077 void
exec_unmap_first_page(struct image_params * imgp)1078 exec_unmap_first_page(struct image_params *imgp)
1079 {
1080 vm_page_t m;
1081
1082 if (imgp->firstpage != NULL) {
1083 m = sf_buf_page(imgp->firstpage);
1084 sf_buf_free(imgp->firstpage);
1085 imgp->firstpage = NULL;
1086 vm_page_unwire(m, PQ_ACTIVE);
1087 }
1088 }
1089
1090 void
exec_onexec_old(struct thread * td)1091 exec_onexec_old(struct thread *td)
1092 {
1093 sigfastblock_clear(td);
1094 umtx_exec(td->td_proc);
1095 }
1096
1097 /*
1098 * This is an optimization which removes the unmanaged shared page
1099 * mapping. In combination with pmap_remove_pages(), which cleans all
1100 * managed mappings in the process' vmspace pmap, no work will be left
1101 * for pmap_remove(min, max).
1102 */
1103 void
exec_free_abi_mappings(struct proc * p)1104 exec_free_abi_mappings(struct proc *p)
1105 {
1106 struct vmspace *vmspace;
1107 struct sysentvec *sv;
1108
1109 vmspace = p->p_vmspace;
1110 if (refcount_load(&vmspace->vm_refcnt) != 1)
1111 return;
1112
1113 sv = p->p_sysent;
1114 if (sv->sv_shared_page_obj == NULL)
1115 return;
1116
1117 pmap_remove(vmspace_pmap(vmspace), sv->sv_shared_page_base,
1118 sv->sv_shared_page_base + sv->sv_shared_page_len);
1119 }
1120
1121 /*
1122 * Run down the current address space and install a new one. Map the shared
1123 * page.
1124 */
1125 int
exec_new_vmspace(struct image_params * imgp,struct sysentvec * sv)1126 exec_new_vmspace(struct image_params *imgp, struct sysentvec *sv)
1127 {
1128 int error;
1129 struct proc *p = imgp->proc;
1130 struct vmspace *vmspace = p->p_vmspace;
1131 struct thread *td = curthread;
1132 vm_object_t obj;
1133 vm_offset_t sv_minuser;
1134 vm_map_t map;
1135
1136 imgp->vmspace_destroyed = true;
1137 imgp->sysent = sv;
1138
1139 if (p->p_sysent->sv_onexec_old != NULL)
1140 p->p_sysent->sv_onexec_old(td);
1141 itimers_exec(p);
1142 if (sv->sv_onexec != NULL)
1143 sv->sv_onexec(p, imgp);
1144
1145 EVENTHANDLER_DIRECT_INVOKE(process_exec, p, imgp);
1146
1147 /*
1148 * Blow away entire process VM, if address space not shared,
1149 * otherwise, create a new VM space so that other threads are
1150 * not disrupted
1151 */
1152 map = &vmspace->vm_map;
1153 if (map_at_zero)
1154 sv_minuser = sv->sv_minuser;
1155 else
1156 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE);
1157 if (refcount_load(&vmspace->vm_refcnt) == 1 &&
1158 vm_map_min(map) == sv_minuser &&
1159 vm_map_max(map) == sv->sv_maxuser &&
1160 cpu_exec_vmspace_reuse(p, map)) {
1161 exec_free_abi_mappings(p);
1162 shmexit(vmspace);
1163 pmap_remove_pages(vmspace_pmap(vmspace));
1164 vm_map_remove(map, vm_map_min(map), vm_map_max(map));
1165 /*
1166 * An exec terminates mlockall(MCL_FUTURE).
1167 * ASLR and W^X states must be re-evaluated.
1168 */
1169 vm_map_lock(map);
1170 vm_map_modflags(map, 0, MAP_WIREFUTURE | MAP_ASLR |
1171 MAP_ASLR_IGNSTART | MAP_ASLR_STACK | MAP_WXORX);
1172 vm_map_unlock(map);
1173 } else {
1174 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser);
1175 if (error)
1176 return (error);
1177 vmspace = p->p_vmspace;
1178 map = &vmspace->vm_map;
1179 }
1180 map->flags |= imgp->map_flags;
1181
1182 /* Map a shared page */
1183 obj = sv->sv_shared_page_obj;
1184 if (obj != NULL) {
1185 vm_object_reference(obj);
1186 error = vm_map_fixed(map, obj, 0,
1187 sv->sv_shared_page_base, sv->sv_shared_page_len,
1188 VM_PROT_READ | VM_PROT_EXECUTE,
1189 VM_PROT_READ | VM_PROT_EXECUTE,
1190 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE);
1191 if (error != KERN_SUCCESS) {
1192 vm_object_deallocate(obj);
1193 return (vm_mmap_to_errno(error));
1194 }
1195 }
1196
1197 return (0);
1198 }
1199
1200 /*
1201 * Compute the stack size limit and map the main process stack.
1202 */
1203 int
exec_map_stack(struct image_params * imgp)1204 exec_map_stack(struct image_params *imgp)
1205 {
1206 struct rlimit rlim_stack;
1207 struct sysentvec *sv;
1208 struct proc *p;
1209 vm_map_t map;
1210 struct vmspace *vmspace;
1211 vm_offset_t stack_addr, stack_top;
1212 u_long ssiz;
1213 int error, find_space, stack_off;
1214 vm_prot_t stack_prot;
1215
1216 p = imgp->proc;
1217 sv = p->p_sysent;
1218
1219 if (imgp->stack_sz != 0) {
1220 ssiz = trunc_page(imgp->stack_sz);
1221 PROC_LOCK(p);
1222 lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack);
1223 PROC_UNLOCK(p);
1224 if (ssiz > rlim_stack.rlim_max)
1225 ssiz = rlim_stack.rlim_max;
1226 if (ssiz > rlim_stack.rlim_cur) {
1227 rlim_stack.rlim_cur = ssiz;
1228 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack);
1229 }
1230 } else if (sv->sv_maxssiz != NULL) {
1231 ssiz = *sv->sv_maxssiz;
1232 } else {
1233 ssiz = maxssiz;
1234 }
1235
1236 vmspace = p->p_vmspace;
1237 map = &vmspace->vm_map;
1238
1239 stack_prot = sv->sv_shared_page_obj != NULL && imgp->stack_prot != 0 ?
1240 imgp->stack_prot : sv->sv_stackprot;
1241 if ((map->flags & MAP_ASLR_STACK) != 0) {
1242 stack_addr = round_page((vm_offset_t)p->p_vmspace->vm_daddr +
1243 lim_max(curthread, RLIMIT_DATA));
1244 find_space = VMFS_ANY_SPACE;
1245 } else {
1246 stack_addr = sv->sv_usrstack - ssiz;
1247 find_space = VMFS_NO_SPACE;
1248 }
1249 error = vm_map_find(map, NULL, 0, &stack_addr, (vm_size_t)ssiz,
1250 sv->sv_usrstack, find_space, stack_prot, VM_PROT_ALL,
1251 MAP_STACK_GROWS_DOWN);
1252 if (error != KERN_SUCCESS) {
1253 uprintf("exec_new_vmspace: mapping stack size %#jx prot %#x "
1254 "failed, mach error %d errno %d\n", (uintmax_t)ssiz,
1255 stack_prot, error, vm_mmap_to_errno(error));
1256 return (vm_mmap_to_errno(error));
1257 }
1258
1259 stack_top = stack_addr + ssiz;
1260 if ((map->flags & MAP_ASLR_STACK) != 0) {
1261 /* Randomize within the first page of the stack. */
1262 arc4rand(&stack_off, sizeof(stack_off), 0);
1263 stack_top -= rounddown2(stack_off & PAGE_MASK, sizeof(void *));
1264 }
1265
1266 /*
1267 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they
1268 * are still used to enforce the stack rlimit on the process stack.
1269 */
1270 vmspace->vm_maxsaddr = (char *)stack_addr;
1271 vmspace->vm_stacktop = stack_top;
1272 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT;
1273
1274 return (0);
1275 }
1276
1277 /*
1278 * Copy out argument and environment strings from the old process address
1279 * space into the temporary string buffer.
1280 */
1281 int
exec_copyin_args(struct image_args * args,const char * fname,enum uio_seg segflg,char ** argv,char ** envv)1282 exec_copyin_args(struct image_args *args, const char *fname,
1283 enum uio_seg segflg, char **argv, char **envv)
1284 {
1285 u_long arg, env;
1286 int error;
1287
1288 bzero(args, sizeof(*args));
1289 if (argv == NULL)
1290 return (EFAULT);
1291
1292 /*
1293 * Allocate demand-paged memory for the file name, argument, and
1294 * environment strings.
1295 */
1296 error = exec_alloc_args(args);
1297 if (error != 0)
1298 return (error);
1299
1300 /*
1301 * Copy the file name.
1302 */
1303 error = exec_args_add_fname(args, fname, segflg);
1304 if (error != 0)
1305 goto err_exit;
1306
1307 /*
1308 * extract arguments first
1309 */
1310 for (;;) {
1311 error = fueword(argv++, &arg);
1312 if (error == -1) {
1313 error = EFAULT;
1314 goto err_exit;
1315 }
1316 if (arg == 0)
1317 break;
1318 error = exec_args_add_arg(args, (char *)(uintptr_t)arg,
1319 UIO_USERSPACE);
1320 if (error != 0)
1321 goto err_exit;
1322 }
1323
1324 /*
1325 * extract environment strings
1326 */
1327 if (envv) {
1328 for (;;) {
1329 error = fueword(envv++, &env);
1330 if (error == -1) {
1331 error = EFAULT;
1332 goto err_exit;
1333 }
1334 if (env == 0)
1335 break;
1336 error = exec_args_add_env(args,
1337 (char *)(uintptr_t)env, UIO_USERSPACE);
1338 if (error != 0)
1339 goto err_exit;
1340 }
1341 }
1342
1343 return (0);
1344
1345 err_exit:
1346 exec_free_args(args);
1347 return (error);
1348 }
1349
1350 int
exec_copyin_data_fds(struct thread * td,struct image_args * args,const void * data,size_t datalen,const int * fds,size_t fdslen)1351 exec_copyin_data_fds(struct thread *td, struct image_args *args,
1352 const void *data, size_t datalen, const int *fds, size_t fdslen)
1353 {
1354 struct filedesc *ofdp;
1355 const char *p;
1356 int *kfds;
1357 int error;
1358
1359 memset(args, '\0', sizeof(*args));
1360 ofdp = td->td_proc->p_fd;
1361 if (datalen >= ARG_MAX || fdslen >= ofdp->fd_nfiles)
1362 return (E2BIG);
1363 error = exec_alloc_args(args);
1364 if (error != 0)
1365 return (error);
1366
1367 args->begin_argv = args->buf;
1368 args->stringspace = ARG_MAX;
1369
1370 if (datalen > 0) {
1371 /*
1372 * Argument buffer has been provided. Copy it into the
1373 * kernel as a single string and add a terminating null
1374 * byte.
1375 */
1376 error = copyin(data, args->begin_argv, datalen);
1377 if (error != 0)
1378 goto err_exit;
1379 args->begin_argv[datalen] = '\0';
1380 args->endp = args->begin_argv + datalen + 1;
1381 args->stringspace -= datalen + 1;
1382
1383 /*
1384 * Traditional argument counting. Count the number of
1385 * null bytes.
1386 */
1387 for (p = args->begin_argv; p < args->endp; ++p)
1388 if (*p == '\0')
1389 ++args->argc;
1390 } else {
1391 /* No argument buffer provided. */
1392 args->endp = args->begin_argv;
1393 }
1394
1395 /* Create new file descriptor table. */
1396 kfds = malloc(fdslen * sizeof(int), M_TEMP, M_WAITOK);
1397 error = copyin(fds, kfds, fdslen * sizeof(int));
1398 if (error != 0) {
1399 free(kfds, M_TEMP);
1400 goto err_exit;
1401 }
1402 error = fdcopy_remapped(ofdp, kfds, fdslen, &args->fdp);
1403 free(kfds, M_TEMP);
1404 if (error != 0)
1405 goto err_exit;
1406
1407 return (0);
1408 err_exit:
1409 exec_free_args(args);
1410 return (error);
1411 }
1412
1413 struct exec_args_kva {
1414 vm_offset_t addr;
1415 u_int gen;
1416 SLIST_ENTRY(exec_args_kva) next;
1417 };
1418
1419 DPCPU_DEFINE_STATIC(struct exec_args_kva *, exec_args_kva);
1420
1421 static SLIST_HEAD(, exec_args_kva) exec_args_kva_freelist;
1422 static struct mtx exec_args_kva_mtx;
1423 static u_int exec_args_gen;
1424
1425 static void
exec_prealloc_args_kva(void * arg __unused)1426 exec_prealloc_args_kva(void *arg __unused)
1427 {
1428 struct exec_args_kva *argkva;
1429 u_int i;
1430
1431 SLIST_INIT(&exec_args_kva_freelist);
1432 mtx_init(&exec_args_kva_mtx, "exec args kva", NULL, MTX_DEF);
1433 for (i = 0; i < exec_map_entries; i++) {
1434 argkva = malloc(sizeof(*argkva), M_PARGS, M_WAITOK);
1435 argkva->addr = kmap_alloc_wait(exec_map, exec_map_entry_size);
1436 argkva->gen = exec_args_gen;
1437 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next);
1438 }
1439 }
1440 SYSINIT(exec_args_kva, SI_SUB_EXEC, SI_ORDER_ANY, exec_prealloc_args_kva, NULL);
1441
1442 static vm_offset_t
exec_alloc_args_kva(void ** cookie)1443 exec_alloc_args_kva(void **cookie)
1444 {
1445 struct exec_args_kva *argkva;
1446
1447 argkva = (void *)atomic_readandclear_ptr(
1448 (uintptr_t *)DPCPU_PTR(exec_args_kva));
1449 if (argkva == NULL) {
1450 mtx_lock(&exec_args_kva_mtx);
1451 while ((argkva = SLIST_FIRST(&exec_args_kva_freelist)) == NULL)
1452 (void)mtx_sleep(&exec_args_kva_freelist,
1453 &exec_args_kva_mtx, 0, "execkva", 0);
1454 SLIST_REMOVE_HEAD(&exec_args_kva_freelist, next);
1455 mtx_unlock(&exec_args_kva_mtx);
1456 }
1457 kasan_mark((void *)argkva->addr, exec_map_entry_size,
1458 exec_map_entry_size, 0);
1459 *(struct exec_args_kva **)cookie = argkva;
1460 return (argkva->addr);
1461 }
1462
1463 static void
exec_release_args_kva(struct exec_args_kva * argkva,u_int gen)1464 exec_release_args_kva(struct exec_args_kva *argkva, u_int gen)
1465 {
1466 vm_offset_t base;
1467
1468 base = argkva->addr;
1469 kasan_mark((void *)argkva->addr, 0, exec_map_entry_size,
1470 KASAN_EXEC_ARGS_FREED);
1471 if (argkva->gen != gen) {
1472 (void)vm_map_madvise(exec_map, base, base + exec_map_entry_size,
1473 MADV_FREE);
1474 argkva->gen = gen;
1475 }
1476 if (!atomic_cmpset_ptr((uintptr_t *)DPCPU_PTR(exec_args_kva),
1477 (uintptr_t)NULL, (uintptr_t)argkva)) {
1478 mtx_lock(&exec_args_kva_mtx);
1479 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next);
1480 wakeup_one(&exec_args_kva_freelist);
1481 mtx_unlock(&exec_args_kva_mtx);
1482 }
1483 }
1484
1485 static void
exec_free_args_kva(void * cookie)1486 exec_free_args_kva(void *cookie)
1487 {
1488
1489 exec_release_args_kva(cookie, exec_args_gen);
1490 }
1491
1492 static void
exec_args_kva_lowmem(void * arg __unused)1493 exec_args_kva_lowmem(void *arg __unused)
1494 {
1495 SLIST_HEAD(, exec_args_kva) head;
1496 struct exec_args_kva *argkva;
1497 u_int gen;
1498 int i;
1499
1500 gen = atomic_fetchadd_int(&exec_args_gen, 1) + 1;
1501
1502 /*
1503 * Force an madvise of each KVA range. Any currently allocated ranges
1504 * will have MADV_FREE applied once they are freed.
1505 */
1506 SLIST_INIT(&head);
1507 mtx_lock(&exec_args_kva_mtx);
1508 SLIST_SWAP(&head, &exec_args_kva_freelist, exec_args_kva);
1509 mtx_unlock(&exec_args_kva_mtx);
1510 while ((argkva = SLIST_FIRST(&head)) != NULL) {
1511 SLIST_REMOVE_HEAD(&head, next);
1512 exec_release_args_kva(argkva, gen);
1513 }
1514
1515 CPU_FOREACH(i) {
1516 argkva = (void *)atomic_readandclear_ptr(
1517 (uintptr_t *)DPCPU_ID_PTR(i, exec_args_kva));
1518 if (argkva != NULL)
1519 exec_release_args_kva(argkva, gen);
1520 }
1521 }
1522 EVENTHANDLER_DEFINE(vm_lowmem, exec_args_kva_lowmem, NULL,
1523 EVENTHANDLER_PRI_ANY);
1524
1525 /*
1526 * Allocate temporary demand-paged, zero-filled memory for the file name,
1527 * argument, and environment strings.
1528 */
1529 int
exec_alloc_args(struct image_args * args)1530 exec_alloc_args(struct image_args *args)
1531 {
1532
1533 args->buf = (char *)exec_alloc_args_kva(&args->bufkva);
1534 return (0);
1535 }
1536
1537 void
exec_free_args(struct image_args * args)1538 exec_free_args(struct image_args *args)
1539 {
1540
1541 if (args->buf != NULL) {
1542 exec_free_args_kva(args->bufkva);
1543 args->buf = NULL;
1544 }
1545 if (args->fname_buf != NULL) {
1546 free(args->fname_buf, M_TEMP);
1547 args->fname_buf = NULL;
1548 }
1549 if (args->fdp != NULL)
1550 fdescfree_remapped(args->fdp);
1551 }
1552
1553 /*
1554 * A set to functions to fill struct image args.
1555 *
1556 * NOTE: exec_args_add_fname() must be called (possibly with a NULL
1557 * fname) before the other functions. All exec_args_add_arg() calls must
1558 * be made before any exec_args_add_env() calls. exec_args_adjust_args()
1559 * may be called any time after exec_args_add_fname().
1560 *
1561 * exec_args_add_fname() - install path to be executed
1562 * exec_args_add_arg() - append an argument string
1563 * exec_args_add_env() - append an env string
1564 * exec_args_adjust_args() - adjust location of the argument list to
1565 * allow new arguments to be prepended
1566 */
1567 int
exec_args_add_fname(struct image_args * args,const char * fname,enum uio_seg segflg)1568 exec_args_add_fname(struct image_args *args, const char *fname,
1569 enum uio_seg segflg)
1570 {
1571 int error;
1572 size_t length;
1573
1574 KASSERT(args->fname == NULL, ("fname already appended"));
1575 KASSERT(args->endp == NULL, ("already appending to args"));
1576
1577 if (fname != NULL) {
1578 args->fname = args->buf;
1579 error = segflg == UIO_SYSSPACE ?
1580 copystr(fname, args->fname, PATH_MAX, &length) :
1581 copyinstr(fname, args->fname, PATH_MAX, &length);
1582 if (error != 0)
1583 return (error == ENAMETOOLONG ? E2BIG : error);
1584 } else
1585 length = 0;
1586
1587 /* Set up for _arg_*()/_env_*() */
1588 args->endp = args->buf + length;
1589 /* begin_argv must be set and kept updated */
1590 args->begin_argv = args->endp;
1591 KASSERT(exec_map_entry_size - length >= ARG_MAX,
1592 ("too little space remaining for arguments %zu < %zu",
1593 exec_map_entry_size - length, (size_t)ARG_MAX));
1594 args->stringspace = ARG_MAX;
1595
1596 return (0);
1597 }
1598
1599 static int
exec_args_add_str(struct image_args * args,const char * str,enum uio_seg segflg,int * countp)1600 exec_args_add_str(struct image_args *args, const char *str,
1601 enum uio_seg segflg, int *countp)
1602 {
1603 int error;
1604 size_t length;
1605
1606 KASSERT(args->endp != NULL, ("endp not initialized"));
1607 KASSERT(args->begin_argv != NULL, ("begin_argp not initialized"));
1608
1609 error = (segflg == UIO_SYSSPACE) ?
1610 copystr(str, args->endp, args->stringspace, &length) :
1611 copyinstr(str, args->endp, args->stringspace, &length);
1612 if (error != 0)
1613 return (error == ENAMETOOLONG ? E2BIG : error);
1614 args->stringspace -= length;
1615 args->endp += length;
1616 (*countp)++;
1617
1618 return (0);
1619 }
1620
1621 int
exec_args_add_arg(struct image_args * args,const char * argp,enum uio_seg segflg)1622 exec_args_add_arg(struct image_args *args, const char *argp,
1623 enum uio_seg segflg)
1624 {
1625
1626 KASSERT(args->envc == 0, ("appending args after env"));
1627
1628 return (exec_args_add_str(args, argp, segflg, &args->argc));
1629 }
1630
1631 int
exec_args_add_env(struct image_args * args,const char * envp,enum uio_seg segflg)1632 exec_args_add_env(struct image_args *args, const char *envp,
1633 enum uio_seg segflg)
1634 {
1635
1636 if (args->envc == 0)
1637 args->begin_envv = args->endp;
1638
1639 return (exec_args_add_str(args, envp, segflg, &args->envc));
1640 }
1641
1642 int
exec_args_adjust_args(struct image_args * args,size_t consume,ssize_t extend)1643 exec_args_adjust_args(struct image_args *args, size_t consume, ssize_t extend)
1644 {
1645 ssize_t offset;
1646
1647 KASSERT(args->endp != NULL, ("endp not initialized"));
1648 KASSERT(args->begin_argv != NULL, ("begin_argp not initialized"));
1649
1650 offset = extend - consume;
1651 if (args->stringspace < offset)
1652 return (E2BIG);
1653 memmove(args->begin_argv + extend, args->begin_argv + consume,
1654 args->endp - args->begin_argv + consume);
1655 if (args->envc > 0)
1656 args->begin_envv += offset;
1657 args->endp += offset;
1658 args->stringspace -= offset;
1659 return (0);
1660 }
1661
1662 char *
exec_args_get_begin_envv(struct image_args * args)1663 exec_args_get_begin_envv(struct image_args *args)
1664 {
1665
1666 KASSERT(args->endp != NULL, ("endp not initialized"));
1667
1668 if (args->envc > 0)
1669 return (args->begin_envv);
1670 return (args->endp);
1671 }
1672
1673 /*
1674 * Copy strings out to the new process address space, constructing new arg
1675 * and env vector tables. Return a pointer to the base so that it can be used
1676 * as the initial stack pointer.
1677 */
1678 int
exec_copyout_strings(struct image_params * imgp,uintptr_t * stack_base)1679 exec_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
1680 {
1681 int argc, envc;
1682 char **vectp;
1683 char *stringp;
1684 uintptr_t destp, ustringp;
1685 struct ps_strings *arginfo;
1686 struct proc *p;
1687 struct sysentvec *sysent;
1688 size_t execpath_len;
1689 int error, szsigcode;
1690 char canary[sizeof(long) * 8];
1691
1692 p = imgp->proc;
1693 sysent = p->p_sysent;
1694
1695 destp = PROC_PS_STRINGS(p);
1696 arginfo = imgp->ps_strings = (void *)destp;
1697
1698 /*
1699 * Install sigcode.
1700 */
1701 if (sysent->sv_sigcode_base == 0 && sysent->sv_szsigcode != NULL) {
1702 szsigcode = *(sysent->sv_szsigcode);
1703 destp -= szsigcode;
1704 destp = rounddown2(destp, sizeof(void *));
1705 error = copyout(sysent->sv_sigcode, (void *)destp, szsigcode);
1706 if (error != 0)
1707 return (error);
1708 }
1709
1710 /*
1711 * Copy the image path for the rtld.
1712 */
1713 if (imgp->execpath != NULL && imgp->auxargs != NULL) {
1714 execpath_len = strlen(imgp->execpath) + 1;
1715 destp -= execpath_len;
1716 destp = rounddown2(destp, sizeof(void *));
1717 imgp->execpathp = (void *)destp;
1718 error = copyout(imgp->execpath, imgp->execpathp, execpath_len);
1719 if (error != 0)
1720 return (error);
1721 }
1722
1723 /*
1724 * Prepare the canary for SSP.
1725 */
1726 arc4rand(canary, sizeof(canary), 0);
1727 destp -= sizeof(canary);
1728 imgp->canary = (void *)destp;
1729 error = copyout(canary, imgp->canary, sizeof(canary));
1730 if (error != 0)
1731 return (error);
1732 imgp->canarylen = sizeof(canary);
1733
1734 /*
1735 * Prepare the pagesizes array.
1736 */
1737 imgp->pagesizeslen = sizeof(pagesizes[0]) * MAXPAGESIZES;
1738 destp -= imgp->pagesizeslen;
1739 destp = rounddown2(destp, sizeof(void *));
1740 imgp->pagesizes = (void *)destp;
1741 error = copyout(pagesizes, imgp->pagesizes, imgp->pagesizeslen);
1742 if (error != 0)
1743 return (error);
1744
1745 /*
1746 * Allocate room for the argument and environment strings.
1747 */
1748 destp -= ARG_MAX - imgp->args->stringspace;
1749 destp = rounddown2(destp, sizeof(void *));
1750 ustringp = destp;
1751
1752 if (imgp->auxargs) {
1753 /*
1754 * Allocate room on the stack for the ELF auxargs
1755 * array. It has up to AT_COUNT entries.
1756 */
1757 destp -= AT_COUNT * sizeof(Elf_Auxinfo);
1758 destp = rounddown2(destp, sizeof(void *));
1759 }
1760
1761 vectp = (char **)destp;
1762
1763 /*
1764 * Allocate room for the argv[] and env vectors including the
1765 * terminating NULL pointers.
1766 */
1767 vectp -= imgp->args->argc + 1 + imgp->args->envc + 1;
1768
1769 /*
1770 * vectp also becomes our initial stack base
1771 */
1772 *stack_base = (uintptr_t)vectp;
1773
1774 stringp = imgp->args->begin_argv;
1775 argc = imgp->args->argc;
1776 envc = imgp->args->envc;
1777
1778 /*
1779 * Copy out strings - arguments and environment.
1780 */
1781 error = copyout(stringp, (void *)ustringp,
1782 ARG_MAX - imgp->args->stringspace);
1783 if (error != 0)
1784 return (error);
1785
1786 /*
1787 * Fill in "ps_strings" struct for ps, w, etc.
1788 */
1789 imgp->argv = vectp;
1790 if (suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp) != 0 ||
1791 suword32(&arginfo->ps_nargvstr, argc) != 0)
1792 return (EFAULT);
1793
1794 /*
1795 * Fill in argument portion of vector table.
1796 */
1797 for (; argc > 0; --argc) {
1798 if (suword(vectp++, ustringp) != 0)
1799 return (EFAULT);
1800 while (*stringp++ != 0)
1801 ustringp++;
1802 ustringp++;
1803 }
1804
1805 /* a null vector table pointer separates the argp's from the envp's */
1806 if (suword(vectp++, 0) != 0)
1807 return (EFAULT);
1808
1809 imgp->envv = vectp;
1810 if (suword(&arginfo->ps_envstr, (long)(intptr_t)vectp) != 0 ||
1811 suword32(&arginfo->ps_nenvstr, envc) != 0)
1812 return (EFAULT);
1813
1814 /*
1815 * Fill in environment portion of vector table.
1816 */
1817 for (; envc > 0; --envc) {
1818 if (suword(vectp++, ustringp) != 0)
1819 return (EFAULT);
1820 while (*stringp++ != 0)
1821 ustringp++;
1822 ustringp++;
1823 }
1824
1825 /* end of vector table is a null pointer */
1826 if (suword(vectp, 0) != 0)
1827 return (EFAULT);
1828
1829 if (imgp->auxargs) {
1830 vectp++;
1831 error = imgp->sysent->sv_copyout_auxargs(imgp,
1832 (uintptr_t)vectp);
1833 if (error != 0)
1834 return (error);
1835 }
1836
1837 return (0);
1838 }
1839
1840 /*
1841 * Check permissions of file to execute.
1842 * Called with imgp->vp locked.
1843 * Return 0 for success or error code on failure.
1844 */
1845 int
exec_check_permissions(struct image_params * imgp)1846 exec_check_permissions(struct image_params *imgp)
1847 {
1848 struct vnode *vp = imgp->vp;
1849 struct vattr *attr = imgp->attr;
1850 struct thread *td;
1851 int error;
1852
1853 td = curthread;
1854
1855 /* Get file attributes */
1856 error = VOP_GETATTR(vp, attr, td->td_ucred);
1857 if (error)
1858 return (error);
1859
1860 #ifdef MAC
1861 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp);
1862 if (error)
1863 return (error);
1864 #endif
1865
1866 /*
1867 * 1) Check if file execution is disabled for the filesystem that
1868 * this file resides on.
1869 * 2) Ensure that at least one execute bit is on. Otherwise, a
1870 * privileged user will always succeed, and we don't want this
1871 * to happen unless the file really is executable.
1872 * 3) Ensure that the file is a regular file.
1873 */
1874 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) ||
1875 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 ||
1876 (attr->va_type != VREG))
1877 return (EACCES);
1878
1879 /*
1880 * Zero length files can't be exec'd
1881 */
1882 if (attr->va_size == 0)
1883 return (ENOEXEC);
1884
1885 /*
1886 * Check for execute permission to file based on current credentials.
1887 */
1888 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td);
1889 if (error)
1890 return (error);
1891
1892 /*
1893 * Check number of open-for-writes on the file and deny execution
1894 * if there are any.
1895 *
1896 * Add a text reference now so no one can write to the
1897 * executable while we're activating it.
1898 *
1899 * Remember if this was set before and unset it in case this is not
1900 * actually an executable image.
1901 */
1902 error = VOP_SET_TEXT(vp);
1903 if (error != 0)
1904 return (error);
1905 imgp->textset = true;
1906
1907 /*
1908 * Call filesystem specific open routine (which does nothing in the
1909 * general case).
1910 */
1911 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL);
1912 if (error == 0)
1913 imgp->opened = true;
1914 return (error);
1915 }
1916
1917 /*
1918 * Exec handler registration
1919 */
1920 int
exec_register(const struct execsw * execsw_arg)1921 exec_register(const struct execsw *execsw_arg)
1922 {
1923 const struct execsw **es, **xs, **newexecsw;
1924 u_int count = 2; /* New slot and trailing NULL */
1925
1926 if (execsw)
1927 for (es = execsw; *es; es++)
1928 count++;
1929 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
1930 xs = newexecsw;
1931 if (execsw)
1932 for (es = execsw; *es; es++)
1933 *xs++ = *es;
1934 *xs++ = execsw_arg;
1935 *xs = NULL;
1936 if (execsw)
1937 free(execsw, M_TEMP);
1938 execsw = newexecsw;
1939 return (0);
1940 }
1941
1942 int
exec_unregister(const struct execsw * execsw_arg)1943 exec_unregister(const struct execsw *execsw_arg)
1944 {
1945 const struct execsw **es, **xs, **newexecsw;
1946 int count = 1;
1947
1948 if (execsw == NULL)
1949 panic("unregister with no handlers left?\n");
1950
1951 for (es = execsw; *es; es++) {
1952 if (*es == execsw_arg)
1953 break;
1954 }
1955 if (*es == NULL)
1956 return (ENOENT);
1957 for (es = execsw; *es; es++)
1958 if (*es != execsw_arg)
1959 count++;
1960 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
1961 xs = newexecsw;
1962 for (es = execsw; *es; es++)
1963 if (*es != execsw_arg)
1964 *xs++ = *es;
1965 *xs = NULL;
1966 if (execsw)
1967 free(execsw, M_TEMP);
1968 execsw = newexecsw;
1969 return (0);
1970 }
1971