kern_sharedpage.c revision 193643
1/*- 2 * Copyright (c) 1993, David Greenman 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27#include <sys/cdefs.h> 28__FBSDID("$FreeBSD: head/sys/kern/kern_exec.c 193643 2009-06-07 19:38:26Z alc $"); 29 30#include "opt_hwpmc_hooks.h" 31#include "opt_kdtrace.h" 32#include "opt_ktrace.h" 33#include "opt_vm.h" 34 35#include <sys/param.h> 36#include <sys/systm.h> 37#include <sys/eventhandler.h> 38#include <sys/lock.h> 39#include <sys/mutex.h> 40#include <sys/sysproto.h> 41#include <sys/signalvar.h> 42#include <sys/kernel.h> 43#include <sys/mount.h> 44#include <sys/filedesc.h> 45#include <sys/fcntl.h> 46#include <sys/acct.h> 47#include <sys/exec.h> 48#include <sys/imgact.h> 49#include <sys/imgact_elf.h> 50#include <sys/wait.h> 51#include <sys/malloc.h> 52#include <sys/priv.h> 53#include <sys/proc.h> 54#include <sys/pioctl.h> 55#include <sys/namei.h> 56#include <sys/resourcevar.h> 57#include <sys/sdt.h> 58#include <sys/sf_buf.h> 59#include <sys/syscallsubr.h> 60#include <sys/sysent.h> 61#include <sys/shm.h> 62#include <sys/sysctl.h> 63#include <sys/vnode.h> 64#include <sys/stat.h> 65#ifdef KTRACE 66#include <sys/ktrace.h> 67#endif 68 69#include <vm/vm.h> 70#include <vm/vm_param.h> 71#include <vm/pmap.h> 72#include <vm/vm_page.h> 73#include <vm/vm_map.h> 74#include <vm/vm_kern.h> 75#include <vm/vm_extern.h> 76#include <vm/vm_object.h> 77#include <vm/vm_pager.h> 78 79#ifdef HWPMC_HOOKS 80#include <sys/pmckern.h> 81#endif 82 83#include <machine/reg.h> 84 85#include <security/audit/audit.h> 86#include <security/mac/mac_framework.h> 87 88#ifdef KDTRACE_HOOKS 89#include <sys/dtrace_bsd.h> 90dtrace_execexit_func_t dtrace_fasttrap_exec; 91#endif 92 93SDT_PROVIDER_DECLARE(proc); 94SDT_PROBE_DEFINE(proc, kernel, , exec); 95SDT_PROBE_ARGTYPE(proc, kernel, , exec, 0, "char *"); 96SDT_PROBE_DEFINE(proc, kernel, , exec_failure); 97SDT_PROBE_ARGTYPE(proc, kernel, , exec_failure, 0, "int"); 98SDT_PROBE_DEFINE(proc, kernel, , exec_success); 99SDT_PROBE_ARGTYPE(proc, kernel, , exec_success, 0, "char *"); 100 101MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 102 103static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 104static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 105static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 106static int do_execve(struct thread *td, struct image_args *args, 107 struct mac *mac_p); 108static void exec_free_args(struct image_args *); 109 110/* XXX This should be vm_size_t. */ 111SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD, 112 NULL, 0, sysctl_kern_ps_strings, "LU", ""); 113 114/* XXX This should be vm_size_t. */ 115SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD, 116 NULL, 0, sysctl_kern_usrstack, "LU", ""); 117 118SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 119 NULL, 0, sysctl_kern_stackprot, "I", ""); 120 121u_long ps_arg_cache_limit = PAGE_SIZE / 16; 122SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 123 &ps_arg_cache_limit, 0, ""); 124 125static int 126sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 127{ 128 struct proc *p; 129 int error; 130 131 p = curproc; 132#ifdef SCTL_MASK32 133 if (req->flags & SCTL_MASK32) { 134 unsigned int val; 135 val = (unsigned int)p->p_sysent->sv_psstrings; 136 error = SYSCTL_OUT(req, &val, sizeof(val)); 137 } else 138#endif 139 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 140 sizeof(p->p_sysent->sv_psstrings)); 141 return error; 142} 143 144static int 145sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 146{ 147 struct proc *p; 148 int error; 149 150 p = curproc; 151#ifdef SCTL_MASK32 152 if (req->flags & SCTL_MASK32) { 153 unsigned int val; 154 val = (unsigned int)p->p_sysent->sv_usrstack; 155 error = SYSCTL_OUT(req, &val, sizeof(val)); 156 } else 157#endif 158 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 159 sizeof(p->p_sysent->sv_usrstack)); 160 return error; 161} 162 163static int 164sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 165{ 166 struct proc *p; 167 168 p = curproc; 169 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 170 sizeof(p->p_sysent->sv_stackprot))); 171} 172 173/* 174 * Each of the items is a pointer to a `const struct execsw', hence the 175 * double pointer here. 176 */ 177static const struct execsw **execsw; 178 179#ifndef _SYS_SYSPROTO_H_ 180struct execve_args { 181 char *fname; 182 char **argv; 183 char **envv; 184}; 185#endif 186 187int 188execve(td, uap) 189 struct thread *td; 190 struct execve_args /* { 191 char *fname; 192 char **argv; 193 char **envv; 194 } */ *uap; 195{ 196 int error; 197 struct image_args args; 198 199 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 200 uap->argv, uap->envv); 201 if (error == 0) 202 error = kern_execve(td, &args, NULL); 203 return (error); 204} 205 206#ifndef _SYS_SYSPROTO_H_ 207struct fexecve_args { 208 int fd; 209 char **argv; 210 char **envv; 211} 212#endif 213int 214fexecve(struct thread *td, struct fexecve_args *uap) 215{ 216 int error; 217 struct image_args args; 218 219 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 220 uap->argv, uap->envv); 221 if (error == 0) { 222 args.fd = uap->fd; 223 error = kern_execve(td, &args, NULL); 224 } 225 return (error); 226} 227 228#ifndef _SYS_SYSPROTO_H_ 229struct __mac_execve_args { 230 char *fname; 231 char **argv; 232 char **envv; 233 struct mac *mac_p; 234}; 235#endif 236 237int 238__mac_execve(td, uap) 239 struct thread *td; 240 struct __mac_execve_args /* { 241 char *fname; 242 char **argv; 243 char **envv; 244 struct mac *mac_p; 245 } */ *uap; 246{ 247#ifdef MAC 248 int error; 249 struct image_args args; 250 251 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 252 uap->argv, uap->envv); 253 if (error == 0) 254 error = kern_execve(td, &args, uap->mac_p); 255 return (error); 256#else 257 return (ENOSYS); 258#endif 259} 260 261/* 262 * XXX: kern_execve has the astonishing property of not always returning to 263 * the caller. If sufficiently bad things happen during the call to 264 * do_execve(), it can end up calling exit1(); as a result, callers must 265 * avoid doing anything which they might need to undo (e.g., allocating 266 * memory). 267 */ 268int 269kern_execve(td, args, mac_p) 270 struct thread *td; 271 struct image_args *args; 272 struct mac *mac_p; 273{ 274 struct proc *p = td->td_proc; 275 int error; 276 277 AUDIT_ARG(argv, args->begin_argv, args->argc, 278 args->begin_envv - args->begin_argv); 279 AUDIT_ARG(envv, args->begin_envv, args->envc, 280 args->endp - args->begin_envv); 281 if (p->p_flag & P_HADTHREADS) { 282 PROC_LOCK(p); 283 if (thread_single(SINGLE_BOUNDARY)) { 284 PROC_UNLOCK(p); 285 exec_free_args(args); 286 return (ERESTART); /* Try again later. */ 287 } 288 PROC_UNLOCK(p); 289 } 290 291 error = do_execve(td, args, mac_p); 292 293 if (p->p_flag & P_HADTHREADS) { 294 PROC_LOCK(p); 295 /* 296 * If success, we upgrade to SINGLE_EXIT state to 297 * force other threads to suicide. 298 */ 299 if (error == 0) 300 thread_single(SINGLE_EXIT); 301 else 302 thread_single_end(); 303 PROC_UNLOCK(p); 304 } 305 306 return (error); 307} 308 309/* 310 * In-kernel implementation of execve(). All arguments are assumed to be 311 * userspace pointers from the passed thread. 312 */ 313static int 314do_execve(td, args, mac_p) 315 struct thread *td; 316 struct image_args *args; 317 struct mac *mac_p; 318{ 319 struct proc *p = td->td_proc; 320 struct nameidata nd; 321 struct ucred *newcred = NULL, *oldcred; 322 struct uidinfo *euip; 323 register_t *stack_base; 324 int error, len = 0, i; 325 struct image_params image_params, *imgp; 326 struct vattr attr; 327 int (*img_first)(struct image_params *); 328 struct pargs *oldargs = NULL, *newargs = NULL; 329 struct sigacts *oldsigacts, *newsigacts; 330#ifdef KTRACE 331 struct vnode *tracevp = NULL; 332 struct ucred *tracecred = NULL; 333#endif 334 struct vnode *textvp = NULL, *binvp = NULL; 335 int credential_changing; 336 int vfslocked; 337 int textset; 338#ifdef MAC 339 struct label *interpvplabel = NULL; 340 int will_transition; 341#endif 342#ifdef HWPMC_HOOKS 343 struct pmckern_procexec pe; 344#endif 345 static const char fexecv_proc_title[] = "(fexecv)"; 346 347 vfslocked = 0; 348 imgp = &image_params; 349 350 /* 351 * Lock the process and set the P_INEXEC flag to indicate that 352 * it should be left alone until we're done here. This is 353 * necessary to avoid race conditions - e.g. in ptrace() - 354 * that might allow a local user to illicitly obtain elevated 355 * privileges. 356 */ 357 PROC_LOCK(p); 358 KASSERT((p->p_flag & P_INEXEC) == 0, 359 ("%s(): process already has P_INEXEC flag", __func__)); 360 p->p_flag |= P_INEXEC; 361 PROC_UNLOCK(p); 362 363 /* 364 * Initialize part of the common data 365 */ 366 imgp->proc = p; 367 imgp->execlabel = NULL; 368 imgp->attr = &attr; 369 imgp->entry_addr = 0; 370 imgp->vmspace_destroyed = 0; 371 imgp->interpreted = 0; 372 imgp->opened = 0; 373 imgp->interpreter_name = args->buf + PATH_MAX + ARG_MAX; 374 imgp->auxargs = NULL; 375 imgp->vp = NULL; 376 imgp->object = NULL; 377 imgp->firstpage = NULL; 378 imgp->ps_strings = 0; 379 imgp->auxarg_size = 0; 380 imgp->args = args; 381 imgp->execpath = imgp->freepath = NULL; 382 imgp->execpathp = 0; 383 384#ifdef MAC 385 error = mac_execve_enter(imgp, mac_p); 386 if (error) 387 goto exec_fail; 388#endif 389 390 imgp->image_header = NULL; 391 392 /* 393 * Translate the file name. namei() returns a vnode pointer 394 * in ni_vp amoung other things. 395 * 396 * XXXAUDIT: It would be desirable to also audit the name of the 397 * interpreter if this is an interpreted binary. 398 */ 399 if (args->fname != NULL) { 400 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 401 | MPSAFE | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 402 } 403 404 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 405 406interpret: 407 if (args->fname != NULL) { 408 error = namei(&nd); 409 if (error) 410 goto exec_fail; 411 412 vfslocked = NDHASGIANT(&nd); 413 binvp = nd.ni_vp; 414 imgp->vp = binvp; 415 } else { 416 AUDIT_ARG(fd, args->fd); 417 error = fgetvp(td, args->fd, &binvp); 418 if (error) 419 goto exec_fail; 420 vfslocked = VFS_LOCK_GIANT(binvp->v_mount); 421 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY); 422 AUDIT_ARG(vnode, binvp, ARG_VNODE1); 423 imgp->vp = binvp; 424 } 425 426 /* 427 * Check file permissions (also 'opens' file) 428 */ 429 error = exec_check_permissions(imgp); 430 if (error) 431 goto exec_fail_dealloc; 432 433 imgp->object = imgp->vp->v_object; 434 if (imgp->object != NULL) 435 vm_object_reference(imgp->object); 436 437 /* 438 * Set VV_TEXT now so no one can write to the executable while we're 439 * activating it. 440 * 441 * Remember if this was set before and unset it in case this is not 442 * actually an executable image. 443 */ 444 textset = imgp->vp->v_vflag & VV_TEXT; 445 imgp->vp->v_vflag |= VV_TEXT; 446 447 error = exec_map_first_page(imgp); 448 if (error) 449 goto exec_fail_dealloc; 450 451 imgp->proc->p_osrel = 0; 452 /* 453 * If the current process has a special image activator it 454 * wants to try first, call it. For example, emulating shell 455 * scripts differently. 456 */ 457 error = -1; 458 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 459 error = img_first(imgp); 460 461 /* 462 * Loop through the list of image activators, calling each one. 463 * An activator returns -1 if there is no match, 0 on success, 464 * and an error otherwise. 465 */ 466 for (i = 0; error == -1 && execsw[i]; ++i) { 467 if (execsw[i]->ex_imgact == NULL || 468 execsw[i]->ex_imgact == img_first) { 469 continue; 470 } 471 error = (*execsw[i]->ex_imgact)(imgp); 472 } 473 474 if (error) { 475 if (error == -1) { 476 if (textset == 0) 477 imgp->vp->v_vflag &= ~VV_TEXT; 478 error = ENOEXEC; 479 } 480 goto exec_fail_dealloc; 481 } 482 483 /* 484 * Special interpreter operation, cleanup and loop up to try to 485 * activate the interpreter. 486 */ 487 if (imgp->interpreted) { 488 exec_unmap_first_page(imgp); 489 /* 490 * VV_TEXT needs to be unset for scripts. There is a short 491 * period before we determine that something is a script where 492 * VV_TEXT will be set. The vnode lock is held over this 493 * entire period so nothing should illegitimately be blocked. 494 */ 495 imgp->vp->v_vflag &= ~VV_TEXT; 496 /* free name buffer and old vnode */ 497 if (args->fname != NULL) 498 NDFREE(&nd, NDF_ONLY_PNBUF); 499#ifdef MAC 500 mac_execve_interpreter_enter(binvp, &interpvplabel); 501#endif 502 if (imgp->opened) { 503 VOP_CLOSE(binvp, FREAD, td->td_ucred, td); 504 imgp->opened = 0; 505 } 506 vput(binvp); 507 vm_object_deallocate(imgp->object); 508 imgp->object = NULL; 509 VFS_UNLOCK_GIANT(vfslocked); 510 vfslocked = 0; 511 /* set new name to that of the interpreter */ 512 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME | MPSAFE, 513 UIO_SYSSPACE, imgp->interpreter_name, td); 514 args->fname = imgp->interpreter_name; 515 goto interpret; 516 } 517 518 /* 519 * NB: We unlock the vnode here because it is believed that none 520 * of the sv_copyout_strings/sv_fixup operations require the vnode. 521 */ 522 VOP_UNLOCK(imgp->vp, 0); 523 524 /* 525 * Do the best to calculate the full path to the image file. 526 */ 527 if (imgp->auxargs != NULL && 528 ((args->fname != NULL && args->fname[0] == '/') || 529 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0)) 530 imgp->execpath = args->fname; 531 532 /* 533 * Copy out strings (args and env) and initialize stack base 534 */ 535 if (p->p_sysent->sv_copyout_strings) 536 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 537 else 538 stack_base = exec_copyout_strings(imgp); 539 540 /* 541 * If custom stack fixup routine present for this process 542 * let it do the stack setup. 543 * Else stuff argument count as first item on stack 544 */ 545 if (p->p_sysent->sv_fixup != NULL) 546 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 547 else 548 suword(--stack_base, imgp->args->argc); 549 550 /* 551 * For security and other reasons, the file descriptor table cannot 552 * be shared after an exec. 553 */ 554 fdunshare(p, td); 555 556 /* 557 * Malloc things before we need locks. 558 */ 559 newcred = crget(); 560 euip = uifind(attr.va_uid); 561 i = imgp->args->begin_envv - imgp->args->begin_argv; 562 /* Cache arguments if they fit inside our allowance */ 563 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 564 newargs = pargs_alloc(i); 565 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 566 } 567 568 /* close files on exec */ 569 fdcloseexec(td); 570 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 571 572 /* Get a reference to the vnode prior to locking the proc */ 573 VREF(binvp); 574 575 /* 576 * For security and other reasons, signal handlers cannot 577 * be shared after an exec. The new process gets a copy of the old 578 * handlers. In execsigs(), the new process will have its signals 579 * reset. 580 */ 581 PROC_LOCK(p); 582 if (sigacts_shared(p->p_sigacts)) { 583 oldsigacts = p->p_sigacts; 584 PROC_UNLOCK(p); 585 newsigacts = sigacts_alloc(); 586 sigacts_copy(newsigacts, oldsigacts); 587 PROC_LOCK(p); 588 p->p_sigacts = newsigacts; 589 } else 590 oldsigacts = NULL; 591 592 /* Stop profiling */ 593 stopprofclock(p); 594 595 /* reset caught signals */ 596 execsigs(p); 597 598 /* name this process - nameiexec(p, ndp) */ 599 if (args->fname) { 600 len = min(nd.ni_cnd.cn_namelen,MAXCOMLEN); 601 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, len); 602 } else { 603 if (vn_commname(binvp, p->p_comm, MAXCOMLEN + 1) == 0) 604 len = MAXCOMLEN; 605 else { 606 len = sizeof(fexecv_proc_title); 607 bcopy(fexecv_proc_title, p->p_comm, len); 608 } 609 } 610 p->p_comm[len] = 0; 611 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 612 613 /* 614 * mark as execed, wakeup the process that vforked (if any) and tell 615 * it that it now has its own resources back 616 */ 617 p->p_flag |= P_EXEC; 618 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 619 p->p_flag &= ~P_PPWAIT; 620 cv_broadcast(&p->p_pwait); 621 } 622 623 /* 624 * Implement image setuid/setgid. 625 * 626 * Don't honor setuid/setgid if the filesystem prohibits it or if 627 * the process is being traced. 628 * 629 * XXXMAC: For the time being, use NOSUID to also prohibit 630 * transitions on the file system. 631 */ 632 oldcred = p->p_ucred; 633 credential_changing = 0; 634 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 635 attr.va_uid; 636 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 637 attr.va_gid; 638#ifdef MAC 639 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 640 interpvplabel, imgp); 641 credential_changing |= will_transition; 642#endif 643 644 if (credential_changing && 645 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 646 (p->p_flag & P_TRACED) == 0) { 647 /* 648 * Turn off syscall tracing for set-id programs, except for 649 * root. Record any set-id flags first to make sure that 650 * we do not regain any tracing during a possible block. 651 */ 652 setsugid(p); 653 654#ifdef KTRACE 655 if (p->p_tracevp != NULL && 656 priv_check_cred(oldcred, PRIV_DEBUG_DIFFCRED, 0)) { 657 mtx_lock(&ktrace_mtx); 658 p->p_traceflag = 0; 659 tracevp = p->p_tracevp; 660 p->p_tracevp = NULL; 661 tracecred = p->p_tracecred; 662 p->p_tracecred = NULL; 663 mtx_unlock(&ktrace_mtx); 664 } 665#endif 666 /* 667 * Close any file descriptors 0..2 that reference procfs, 668 * then make sure file descriptors 0..2 are in use. 669 * 670 * setugidsafety() may call closef() and then pfind() 671 * which may grab the process lock. 672 * fdcheckstd() may call falloc() which may block to 673 * allocate memory, so temporarily drop the process lock. 674 */ 675 PROC_UNLOCK(p); 676 setugidsafety(td); 677 VOP_UNLOCK(imgp->vp, 0); 678 error = fdcheckstd(td); 679 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 680 if (error != 0) 681 goto done1; 682 PROC_LOCK(p); 683 /* 684 * Set the new credentials. 685 */ 686 crcopy(newcred, oldcred); 687 if (attr.va_mode & S_ISUID) 688 change_euid(newcred, euip); 689 if (attr.va_mode & S_ISGID) 690 change_egid(newcred, attr.va_gid); 691#ifdef MAC 692 if (will_transition) { 693 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 694 interpvplabel, imgp); 695 } 696#endif 697 /* 698 * Implement correct POSIX saved-id behavior. 699 * 700 * XXXMAC: Note that the current logic will save the 701 * uid and gid if a MAC domain transition occurs, even 702 * though maybe it shouldn't. 703 */ 704 change_svuid(newcred, newcred->cr_uid); 705 change_svgid(newcred, newcred->cr_gid); 706 p->p_ucred = newcred; 707 newcred = NULL; 708 } else { 709 if (oldcred->cr_uid == oldcred->cr_ruid && 710 oldcred->cr_gid == oldcred->cr_rgid) 711 p->p_flag &= ~P_SUGID; 712 /* 713 * Implement correct POSIX saved-id behavior. 714 * 715 * XXX: It's not clear that the existing behavior is 716 * POSIX-compliant. A number of sources indicate that the 717 * saved uid/gid should only be updated if the new ruid is 718 * not equal to the old ruid, or the new euid is not equal 719 * to the old euid and the new euid is not equal to the old 720 * ruid. The FreeBSD code always updates the saved uid/gid. 721 * Also, this code uses the new (replaced) euid and egid as 722 * the source, which may or may not be the right ones to use. 723 */ 724 if (oldcred->cr_svuid != oldcred->cr_uid || 725 oldcred->cr_svgid != oldcred->cr_gid) { 726 crcopy(newcred, oldcred); 727 change_svuid(newcred, newcred->cr_uid); 728 change_svgid(newcred, newcred->cr_gid); 729 p->p_ucred = newcred; 730 newcred = NULL; 731 } 732 } 733 734 /* 735 * Store the vp for use in procfs. This vnode was referenced prior 736 * to locking the proc lock. 737 */ 738 textvp = p->p_textvp; 739 p->p_textvp = binvp; 740 741#ifdef KDTRACE_HOOKS 742 /* 743 * Tell the DTrace fasttrap provider about the exec if it 744 * has declared an interest. 745 */ 746 if (dtrace_fasttrap_exec) 747 dtrace_fasttrap_exec(p); 748#endif 749 750 /* 751 * Notify others that we exec'd, and clear the P_INEXEC flag 752 * as we're now a bona fide freshly-execed process. 753 */ 754 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 755 p->p_flag &= ~P_INEXEC; 756 757 /* 758 * If tracing the process, trap to debugger so breakpoints 759 * can be set before the program executes. 760 * Use tdsignal to deliver signal to current thread, use 761 * psignal may cause the signal to be delivered to wrong thread 762 * because that thread will exit, remember we are going to enter 763 * single thread mode. 764 */ 765 if (p->p_flag & P_TRACED) 766 tdsignal(p, td, SIGTRAP, NULL); 767 768 /* clear "fork but no exec" flag, as we _are_ execing */ 769 p->p_acflag &= ~AFORK; 770 771 /* 772 * Free any previous argument cache and replace it with 773 * the new argument cache, if any. 774 */ 775 oldargs = p->p_args; 776 p->p_args = newargs; 777 newargs = NULL; 778 779#ifdef HWPMC_HOOKS 780 /* 781 * Check if system-wide sampling is in effect or if the 782 * current process is using PMCs. If so, do exec() time 783 * processing. This processing needs to happen AFTER the 784 * P_INEXEC flag is cleared. 785 * 786 * The proc lock needs to be released before taking the PMC 787 * SX. 788 */ 789 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 790 PROC_UNLOCK(p); 791 pe.pm_credentialschanged = credential_changing; 792 pe.pm_entryaddr = imgp->entry_addr; 793 794 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 795 } else 796 PROC_UNLOCK(p); 797#else /* !HWPMC_HOOKS */ 798 PROC_UNLOCK(p); 799#endif 800 801 /* Set values passed into the program in registers. */ 802 if (p->p_sysent->sv_setregs) 803 (*p->p_sysent->sv_setregs)(td, imgp->entry_addr, 804 (u_long)(uintptr_t)stack_base, imgp->ps_strings); 805 else 806 exec_setregs(td, imgp->entry_addr, 807 (u_long)(uintptr_t)stack_base, imgp->ps_strings); 808 809 vfs_mark_atime(imgp->vp, td->td_ucred); 810 811 SDT_PROBE(proc, kernel, , exec_success, args->fname, 0, 0, 0, 0); 812 813done1: 814 /* 815 * Free any resources malloc'd earlier that we didn't use. 816 */ 817 uifree(euip); 818 if (newcred == NULL) 819 crfree(oldcred); 820 else 821 crfree(newcred); 822 VOP_UNLOCK(imgp->vp, 0); 823 824 /* 825 * Handle deferred decrement of ref counts. 826 */ 827 if (textvp != NULL) { 828 int tvfslocked; 829 830 tvfslocked = VFS_LOCK_GIANT(textvp->v_mount); 831 vrele(textvp); 832 VFS_UNLOCK_GIANT(tvfslocked); 833 } 834 if (binvp && error != 0) 835 vrele(binvp); 836#ifdef KTRACE 837 if (tracevp != NULL) { 838 int tvfslocked; 839 840 tvfslocked = VFS_LOCK_GIANT(tracevp->v_mount); 841 vrele(tracevp); 842 VFS_UNLOCK_GIANT(tvfslocked); 843 } 844 if (tracecred != NULL) 845 crfree(tracecred); 846#endif 847 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 848 pargs_drop(oldargs); 849 pargs_drop(newargs); 850 if (oldsigacts != NULL) 851 sigacts_free(oldsigacts); 852 853exec_fail_dealloc: 854 855 /* 856 * free various allocated resources 857 */ 858 if (imgp->firstpage != NULL) 859 exec_unmap_first_page(imgp); 860 861 if (imgp->vp != NULL) { 862 if (args->fname) 863 NDFREE(&nd, NDF_ONLY_PNBUF); 864 if (imgp->opened) 865 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 866 vput(imgp->vp); 867 } 868 869 if (imgp->object != NULL) 870 vm_object_deallocate(imgp->object); 871 872 free(imgp->freepath, M_TEMP); 873 874 if (error == 0) { 875 /* 876 * Stop the process here if its stop event mask has 877 * the S_EXEC bit set. 878 */ 879 STOPEVENT(p, S_EXEC, 0); 880 goto done2; 881 } 882 883exec_fail: 884 /* we're done here, clear P_INEXEC */ 885 PROC_LOCK(p); 886 p->p_flag &= ~P_INEXEC; 887 PROC_UNLOCK(p); 888 889 SDT_PROBE(proc, kernel, , exec_failure, error, 0, 0, 0, 0); 890 891done2: 892#ifdef MAC 893 mac_execve_exit(imgp); 894 mac_execve_interpreter_exit(interpvplabel); 895#endif 896 VFS_UNLOCK_GIANT(vfslocked); 897 exec_free_args(args); 898 899 if (error && imgp->vmspace_destroyed) { 900 /* sorry, no more process anymore. exit gracefully */ 901 exit1(td, W_EXITCODE(0, SIGABRT)); 902 /* NOT REACHED */ 903 } 904 return (error); 905} 906 907int 908exec_map_first_page(imgp) 909 struct image_params *imgp; 910{ 911 int rv, i; 912 int initial_pagein; 913 vm_page_t ma[VM_INITIAL_PAGEIN]; 914 vm_object_t object; 915 916 if (imgp->firstpage != NULL) 917 exec_unmap_first_page(imgp); 918 919 object = imgp->vp->v_object; 920 if (object == NULL) 921 return (EACCES); 922 VM_OBJECT_LOCK(object); 923#if VM_NRESERVLEVEL > 0 924 if ((object->flags & OBJ_COLORED) == 0) { 925 object->flags |= OBJ_COLORED; 926 object->pg_color = 0; 927 } 928#endif 929 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 930 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 931 initial_pagein = VM_INITIAL_PAGEIN; 932 if (initial_pagein > object->size) 933 initial_pagein = object->size; 934 for (i = 1; i < initial_pagein; i++) { 935 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 936 if (ma[i]->valid) 937 break; 938 if ((ma[i]->oflags & VPO_BUSY) || ma[i]->busy) 939 break; 940 vm_page_busy(ma[i]); 941 } else { 942 ma[i] = vm_page_alloc(object, i, 943 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 944 if (ma[i] == NULL) 945 break; 946 } 947 } 948 initial_pagein = i; 949 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 950 ma[0] = vm_page_lookup(object, 0); 951 if ((rv != VM_PAGER_OK) || (ma[0] == NULL)) { 952 if (ma[0]) { 953 vm_page_lock_queues(); 954 vm_page_free(ma[0]); 955 vm_page_unlock_queues(); 956 } 957 VM_OBJECT_UNLOCK(object); 958 return (EIO); 959 } 960 } 961 vm_page_lock_queues(); 962 vm_page_hold(ma[0]); 963 vm_page_unlock_queues(); 964 vm_page_wakeup(ma[0]); 965 VM_OBJECT_UNLOCK(object); 966 967 imgp->firstpage = sf_buf_alloc(ma[0], 0); 968 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 969 970 return (0); 971} 972 973void 974exec_unmap_first_page(imgp) 975 struct image_params *imgp; 976{ 977 vm_page_t m; 978 979 if (imgp->firstpage != NULL) { 980 m = sf_buf_page(imgp->firstpage); 981 sf_buf_free(imgp->firstpage); 982 imgp->firstpage = NULL; 983 vm_page_lock_queues(); 984 vm_page_unhold(m); 985 vm_page_unlock_queues(); 986 } 987} 988 989/* 990 * Destroy old address space, and allocate a new stack 991 * The new stack is only SGROWSIZ large because it is grown 992 * automatically in trap.c. 993 */ 994int 995exec_new_vmspace(imgp, sv) 996 struct image_params *imgp; 997 struct sysentvec *sv; 998{ 999 int error; 1000 struct proc *p = imgp->proc; 1001 struct vmspace *vmspace = p->p_vmspace; 1002 vm_offset_t stack_addr; 1003 vm_map_t map; 1004 u_long ssiz; 1005 1006 imgp->vmspace_destroyed = 1; 1007 imgp->sysent = sv; 1008 1009 /* May be called with Giant held */ 1010 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1011 1012 /* 1013 * Blow away entire process VM, if address space not shared, 1014 * otherwise, create a new VM space so that other threads are 1015 * not disrupted 1016 */ 1017 map = &vmspace->vm_map; 1018 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv->sv_minuser && 1019 vm_map_max(map) == sv->sv_maxuser) { 1020 shmexit(vmspace); 1021 pmap_remove_pages(vmspace_pmap(vmspace)); 1022 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1023 } else { 1024 error = vmspace_exec(p, sv->sv_minuser, sv->sv_maxuser); 1025 if (error) 1026 return (error); 1027 vmspace = p->p_vmspace; 1028 map = &vmspace->vm_map; 1029 } 1030 1031 /* Allocate a new stack */ 1032 if (sv->sv_maxssiz != NULL) 1033 ssiz = *sv->sv_maxssiz; 1034 else 1035 ssiz = maxssiz; 1036 stack_addr = sv->sv_usrstack - ssiz; 1037 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1038 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1039 if (error) 1040 return (error); 1041 1042#ifdef __ia64__ 1043 /* Allocate a new register stack */ 1044 stack_addr = IA64_BACKINGSTORE; 1045 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1046 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP); 1047 if (error) 1048 return (error); 1049#endif 1050 1051 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 1052 * VM_STACK case, but they are still used to monitor the size of the 1053 * process stack so we can check the stack rlimit. 1054 */ 1055 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1056 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1057 1058 return (0); 1059} 1060 1061/* 1062 * Copy out argument and environment strings from the old process address 1063 * space into the temporary string buffer. 1064 */ 1065int 1066exec_copyin_args(struct image_args *args, char *fname, 1067 enum uio_seg segflg, char **argv, char **envv) 1068{ 1069 char *argp, *envp; 1070 int error; 1071 size_t length; 1072 1073 bzero(args, sizeof(*args)); 1074 if (argv == NULL) 1075 return (EFAULT); 1076 /* 1077 * Allocate temporary demand zeroed space for argument and 1078 * environment strings: 1079 * 1080 * o ARG_MAX for argument and environment; 1081 * o MAXSHELLCMDLEN for the name of interpreters. 1082 */ 1083 args->buf = (char *) kmem_alloc_wait(exec_map, 1084 PATH_MAX + ARG_MAX + MAXSHELLCMDLEN); 1085 if (args->buf == NULL) 1086 return (ENOMEM); 1087 args->begin_argv = args->buf; 1088 args->endp = args->begin_argv; 1089 args->stringspace = ARG_MAX; 1090 /* 1091 * Copy the file name. 1092 */ 1093 if (fname != NULL) { 1094 args->fname = args->buf + ARG_MAX; 1095 error = (segflg == UIO_SYSSPACE) ? 1096 copystr(fname, args->fname, PATH_MAX, &length) : 1097 copyinstr(fname, args->fname, PATH_MAX, &length); 1098 if (error != 0) 1099 goto err_exit; 1100 } else 1101 args->fname = NULL; 1102 1103 /* 1104 * extract arguments first 1105 */ 1106 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 1107 if (argp == (caddr_t) -1) { 1108 error = EFAULT; 1109 goto err_exit; 1110 } 1111 if ((error = copyinstr(argp, args->endp, 1112 args->stringspace, &length))) { 1113 if (error == ENAMETOOLONG) 1114 error = E2BIG; 1115 goto err_exit; 1116 } 1117 args->stringspace -= length; 1118 args->endp += length; 1119 args->argc++; 1120 } 1121 1122 args->begin_envv = args->endp; 1123 1124 /* 1125 * extract environment strings 1126 */ 1127 if (envv) { 1128 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) { 1129 if (envp == (caddr_t)-1) { 1130 error = EFAULT; 1131 goto err_exit; 1132 } 1133 if ((error = copyinstr(envp, args->endp, 1134 args->stringspace, &length))) { 1135 if (error == ENAMETOOLONG) 1136 error = E2BIG; 1137 goto err_exit; 1138 } 1139 args->stringspace -= length; 1140 args->endp += length; 1141 args->envc++; 1142 } 1143 } 1144 1145 return (0); 1146 1147err_exit: 1148 exec_free_args(args); 1149 return (error); 1150} 1151 1152static void 1153exec_free_args(struct image_args *args) 1154{ 1155 1156 if (args->buf) { 1157 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf, 1158 PATH_MAX + ARG_MAX + MAXSHELLCMDLEN); 1159 args->buf = NULL; 1160 } 1161} 1162 1163/* 1164 * Copy strings out to the new process address space, constructing new arg 1165 * and env vector tables. Return a pointer to the base so that it can be used 1166 * as the initial stack pointer. 1167 */ 1168register_t * 1169exec_copyout_strings(imgp) 1170 struct image_params *imgp; 1171{ 1172 int argc, envc; 1173 char **vectp; 1174 char *stringp, *destp; 1175 register_t *stack_base; 1176 struct ps_strings *arginfo; 1177 struct proc *p; 1178 size_t execpath_len; 1179 int szsigcode; 1180 1181 /* 1182 * Calculate string base and vector table pointers. 1183 * Also deal with signal trampoline code for this exec type. 1184 */ 1185 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1186 execpath_len = strlen(imgp->execpath) + 1; 1187 else 1188 execpath_len = 0; 1189 p = imgp->proc; 1190 szsigcode = 0; 1191 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1192 if (p->p_sysent->sv_szsigcode != NULL) 1193 szsigcode = *(p->p_sysent->sv_szsigcode); 1194 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 1195 roundup(execpath_len, sizeof(char *)) - 1196 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *)); 1197 1198 /* 1199 * install sigcode 1200 */ 1201 if (szsigcode) 1202 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo - 1203 szsigcode), szsigcode); 1204 1205 /* 1206 * Copy the image path for the rtld. 1207 */ 1208 if (execpath_len != 0) { 1209 imgp->execpathp = (uintptr_t)arginfo - szsigcode - execpath_len; 1210 copyout(imgp->execpath, (void *)imgp->execpathp, 1211 execpath_len); 1212 } 1213 1214 /* 1215 * If we have a valid auxargs ptr, prepare some room 1216 * on the stack. 1217 */ 1218 if (imgp->auxargs) { 1219 /* 1220 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1221 * lower compatibility. 1222 */ 1223 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1224 (AT_COUNT * 2); 1225 /* 1226 * The '+ 2' is for the null pointers at the end of each of 1227 * the arg and env vector sets,and imgp->auxarg_size is room 1228 * for argument of Runtime loader. 1229 */ 1230 vectp = (char **)(destp - (imgp->args->argc + 1231 imgp->args->envc + 2 + imgp->auxarg_size + execpath_len) * 1232 sizeof(char *)); 1233 } else { 1234 /* 1235 * The '+ 2' is for the null pointers at the end of each of 1236 * the arg and env vector sets 1237 */ 1238 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) * 1239 sizeof(char *)); 1240 } 1241 1242 /* 1243 * vectp also becomes our initial stack base 1244 */ 1245 stack_base = (register_t *)vectp; 1246 1247 stringp = imgp->args->begin_argv; 1248 argc = imgp->args->argc; 1249 envc = imgp->args->envc; 1250 1251 /* 1252 * Copy out strings - arguments and environment. 1253 */ 1254 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace); 1255 1256 /* 1257 * Fill in "ps_strings" struct for ps, w, etc. 1258 */ 1259 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1260 suword(&arginfo->ps_nargvstr, argc); 1261 1262 /* 1263 * Fill in argument portion of vector table. 1264 */ 1265 for (; argc > 0; --argc) { 1266 suword(vectp++, (long)(intptr_t)destp); 1267 while (*stringp++ != 0) 1268 destp++; 1269 destp++; 1270 } 1271 1272 /* a null vector table pointer separates the argp's from the envp's */ 1273 suword(vectp++, 0); 1274 1275 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1276 suword(&arginfo->ps_nenvstr, envc); 1277 1278 /* 1279 * Fill in environment portion of vector table. 1280 */ 1281 for (; envc > 0; --envc) { 1282 suword(vectp++, (long)(intptr_t)destp); 1283 while (*stringp++ != 0) 1284 destp++; 1285 destp++; 1286 } 1287 1288 /* end of vector table is a null pointer */ 1289 suword(vectp, 0); 1290 1291 return (stack_base); 1292} 1293 1294/* 1295 * Check permissions of file to execute. 1296 * Called with imgp->vp locked. 1297 * Return 0 for success or error code on failure. 1298 */ 1299int 1300exec_check_permissions(imgp) 1301 struct image_params *imgp; 1302{ 1303 struct vnode *vp = imgp->vp; 1304 struct vattr *attr = imgp->attr; 1305 struct thread *td; 1306 int error; 1307 1308 td = curthread; 1309 1310 /* Get file attributes */ 1311 error = VOP_GETATTR(vp, attr, td->td_ucred); 1312 if (error) 1313 return (error); 1314 1315#ifdef MAC 1316 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1317 if (error) 1318 return (error); 1319#endif 1320 1321 /* 1322 * 1) Check if file execution is disabled for the filesystem that this 1323 * file resides on. 1324 * 2) Insure that at least one execute bit is on - otherwise root 1325 * will always succeed, and we don't want to happen unless the 1326 * file really is executable. 1327 * 3) Insure that the file is a regular file. 1328 */ 1329 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1330 ((attr->va_mode & 0111) == 0) || 1331 (attr->va_type != VREG)) 1332 return (EACCES); 1333 1334 /* 1335 * Zero length files can't be exec'd 1336 */ 1337 if (attr->va_size == 0) 1338 return (ENOEXEC); 1339 1340 /* 1341 * Check for execute permission to file based on current credentials. 1342 */ 1343 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1344 if (error) 1345 return (error); 1346 1347 /* 1348 * Check number of open-for-writes on the file and deny execution 1349 * if there are any. 1350 */ 1351 if (vp->v_writecount) 1352 return (ETXTBSY); 1353 1354 /* 1355 * Call filesystem specific open routine (which does nothing in the 1356 * general case). 1357 */ 1358 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1359 if (error == 0) 1360 imgp->opened = 1; 1361 return (error); 1362} 1363 1364/* 1365 * Exec handler registration 1366 */ 1367int 1368exec_register(execsw_arg) 1369 const struct execsw *execsw_arg; 1370{ 1371 const struct execsw **es, **xs, **newexecsw; 1372 int count = 2; /* New slot and trailing NULL */ 1373 1374 if (execsw) 1375 for (es = execsw; *es; es++) 1376 count++; 1377 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1378 if (newexecsw == NULL) 1379 return (ENOMEM); 1380 xs = newexecsw; 1381 if (execsw) 1382 for (es = execsw; *es; es++) 1383 *xs++ = *es; 1384 *xs++ = execsw_arg; 1385 *xs = NULL; 1386 if (execsw) 1387 free(execsw, M_TEMP); 1388 execsw = newexecsw; 1389 return (0); 1390} 1391 1392int 1393exec_unregister(execsw_arg) 1394 const struct execsw *execsw_arg; 1395{ 1396 const struct execsw **es, **xs, **newexecsw; 1397 int count = 1; 1398 1399 if (execsw == NULL) 1400 panic("unregister with no handlers left?\n"); 1401 1402 for (es = execsw; *es; es++) { 1403 if (*es == execsw_arg) 1404 break; 1405 } 1406 if (*es == NULL) 1407 return (ENOENT); 1408 for (es = execsw; *es; es++) 1409 if (*es != execsw_arg) 1410 count++; 1411 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1412 if (newexecsw == NULL) 1413 return (ENOMEM); 1414 xs = newexecsw; 1415 for (es = execsw; *es; es++) 1416 if (*es != execsw_arg) 1417 *xs++ = *es; 1418 *xs = NULL; 1419 if (execsw) 1420 free(execsw, M_TEMP); 1421 execsw = newexecsw; 1422 return (0); 1423} 1424