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 * $FreeBSD: src/sys/kern/kern_exec.c,v 1.107.2.15 2002/07/30 15:40:46 nectar Exp $ 27 */ 28 29 #include <sys/param.h> 30 #include <sys/systm.h> 31 #include <sys/sysproto.h> 32 #include <sys/kernel.h> 33 #include <sys/mount.h> 34 #include <sys/filedesc.h> 35 #include <sys/fcntl.h> 36 #include <sys/acct.h> 37 #include <sys/exec.h> 38 #include <sys/imgact.h> 39 #include <sys/imgact_elf.h> 40 #include <sys/kern_syscall.h> 41 #include <sys/wait.h> 42 #include <sys/malloc.h> 43 #include <sys/proc.h> 44 #include <sys/priv.h> 45 #include <sys/ktrace.h> 46 #include <sys/signalvar.h> 47 #include <sys/pioctl.h> 48 #include <sys/nlookup.h> 49 #include <sys/sysent.h> 50 #include <sys/shm.h> 51 #include <sys/sysctl.h> 52 #include <sys/vnode.h> 53 #include <sys/vmmeter.h> 54 #include <sys/libkern.h> 55 56 #include <cpu/lwbuf.h> 57 58 #include <vm/vm.h> 59 #include <vm/vm_param.h> 60 #include <sys/lock.h> 61 #include <vm/pmap.h> 62 #include <vm/vm_page.h> 63 #include <vm/vm_map.h> 64 #include <vm/vm_kern.h> 65 #include <vm/vm_extern.h> 66 #include <vm/vm_object.h> 67 #include <vm/vnode_pager.h> 68 #include <vm/vm_pager.h> 69 70 #include <sys/user.h> 71 #include <sys/reg.h> 72 73 #include <sys/refcount.h> 74 #include <sys/thread2.h> 75 #include <sys/mplock2.h> 76 #include <vm/vm_page2.h> 77 78 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 79 MALLOC_DEFINE(M_EXECARGS, "exec-args", "Exec arguments"); 80 81 static register_t *exec_copyout_strings (struct image_params *); 82 83 /* XXX This should be vm_size_t. */ 84 static u_long ps_strings = PS_STRINGS; 85 SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, ""); 86 87 /* XXX This should be vm_size_t. */ 88 static u_long usrstack = USRSTACK; 89 SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, ""); 90 91 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 92 SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 93 &ps_arg_cache_limit, 0, ""); 94 95 int ps_argsopen = 1; 96 SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, ""); 97 98 static int ktrace_suid = 0; 99 SYSCTL_INT(_kern, OID_AUTO, ktrace_suid, CTLFLAG_RW, &ktrace_suid, 0, ""); 100 101 void print_execve_args(struct image_args *args); 102 int debug_execve_args = 0; 103 SYSCTL_INT(_kern, OID_AUTO, debug_execve_args, CTLFLAG_RW, &debug_execve_args, 104 0, ""); 105 106 /* 107 * Exec arguments object cache 108 */ 109 static struct objcache *exec_objcache; 110 111 static 112 void 113 exec_objcache_init(void *arg __unused) 114 { 115 int cluster_limit; 116 size_t limsize; 117 118 /* 119 * Maximum number of concurrent execs. This can be limiting on 120 * systems with a lot of cpu cores but it also eats a significant 121 * amount of memory. 122 */ 123 cluster_limit = (ncpus < 16) ? 16 : ncpus; 124 limsize = kmem_lim_size(); 125 if (limsize > 7 * 1024) 126 cluster_limit *= 2; 127 if (limsize > 15 * 1024) 128 cluster_limit *= 2; 129 130 exec_objcache = objcache_create_mbacked( 131 M_EXECARGS, PATH_MAX + ARG_MAX, 132 cluster_limit, 8, 133 NULL, NULL, NULL); 134 } 135 SYSINIT(exec_objcache, SI_BOOT2_MACHDEP, SI_ORDER_ANY, exec_objcache_init, 0); 136 137 /* 138 * stackgap_random specifies if the stackgap should have a random size added 139 * to it. It must be a power of 2. If non-zero, the stack gap will be 140 * calculated as: ALIGN(karc4random() & (stackgap_random - 1)). 141 */ 142 static int stackgap_random = 1024; 143 static int 144 sysctl_kern_stackgap(SYSCTL_HANDLER_ARGS) 145 { 146 int error, new_val; 147 new_val = stackgap_random; 148 error = sysctl_handle_int(oidp, &new_val, 0, req); 149 if (error != 0 || req->newptr == NULL) 150 return (error); 151 if (new_val > 0 && ((new_val > 16 * PAGE_SIZE) || !powerof2(new_val))) 152 return (EINVAL); 153 stackgap_random = new_val; 154 155 return(0); 156 } 157 158 SYSCTL_PROC(_kern, OID_AUTO, stackgap_random, CTLFLAG_RW|CTLTYPE_INT, 159 0, 0, sysctl_kern_stackgap, "I", 160 "Max random stack gap (power of 2), static gap if negative"); 161 162 void 163 print_execve_args(struct image_args *args) 164 { 165 char *cp; 166 int ndx; 167 168 cp = args->begin_argv; 169 for (ndx = 0; ndx < args->argc; ndx++) { 170 kprintf("\targv[%d]: %s\n", ndx, cp); 171 while (*cp++ != '\0'); 172 } 173 for (ndx = 0; ndx < args->envc; ndx++) { 174 kprintf("\tenvv[%d]: %s\n", ndx, cp); 175 while (*cp++ != '\0'); 176 } 177 } 178 179 /* 180 * Each of the items is a pointer to a `const struct execsw', hence the 181 * double pointer here. 182 */ 183 static const struct execsw **execsw; 184 185 /* 186 * Replace current vmspace with a new binary. 187 * Returns 0 on success, > 0 on recoverable error (use as errno). 188 * Returns -1 on lethal error which demands killing of the current 189 * process! 190 */ 191 int 192 kern_execve(struct nlookupdata *nd, struct image_args *args) 193 { 194 struct thread *td = curthread; 195 struct lwp *lp = td->td_lwp; 196 struct proc *p = td->td_proc; 197 struct vnode *ovp; 198 register_t *stack_base; 199 struct pargs *pa; 200 struct sigacts *ops; 201 struct sigacts *nps; 202 int error, len, i; 203 struct image_params image_params, *imgp; 204 struct vattr attr; 205 int (*img_first) (struct image_params *); 206 207 if (debug_execve_args) { 208 kprintf("%s()\n", __func__); 209 print_execve_args(args); 210 } 211 212 KKASSERT(p); 213 lwkt_gettoken(&p->p_token); 214 imgp = &image_params; 215 216 /* 217 * NOTE: P_INEXEC is handled by exec_new_vmspace() now. We make 218 * no modifications to the process at all until we get there. 219 * 220 * Note that multiple threads may be trying to exec at the same 221 * time. exec_new_vmspace() handles that too. 222 */ 223 224 /* 225 * Initialize part of the common data 226 */ 227 imgp->proc = p; 228 imgp->args = args; 229 imgp->attr = &attr; 230 imgp->entry_addr = 0; 231 imgp->resident = 0; 232 imgp->vmspace_destroyed = 0; 233 imgp->interpreted = 0; 234 imgp->interpreter_name[0] = 0; 235 imgp->auxargs = NULL; 236 imgp->vp = NULL; 237 imgp->firstpage = NULL; 238 imgp->ps_strings = 0; 239 imgp->execpath = imgp->freepath = NULL; 240 imgp->execpathp = 0; 241 imgp->image_header = NULL; 242 243 interpret: 244 245 /* 246 * Translate the file name to a vnode. Unlock the cache entry to 247 * improve parallelism for programs exec'd in parallel. 248 */ 249 nd->nl_flags |= NLC_SHAREDLOCK; 250 if ((error = nlookup(nd)) != 0) 251 goto exec_fail; 252 error = cache_vget(&nd->nl_nch, nd->nl_cred, LK_SHARED, &imgp->vp); 253 KKASSERT(nd->nl_flags & NLC_NCPISLOCKED); 254 nd->nl_flags &= ~NLC_NCPISLOCKED; 255 cache_unlock(&nd->nl_nch); 256 if (error) 257 goto exec_fail; 258 259 /* 260 * Check file permissions (also 'opens' file). 261 * Include also the top level mount in the check. 262 */ 263 error = exec_check_permissions(imgp, nd->nl_nch.mount); 264 if (error) { 265 vn_unlock(imgp->vp); 266 goto exec_fail_dealloc; 267 } 268 269 error = exec_map_first_page(imgp); 270 vn_unlock(imgp->vp); 271 if (error) 272 goto exec_fail_dealloc; 273 274 imgp->proc->p_osrel = 0; 275 276 if (debug_execve_args && imgp->interpreted) { 277 kprintf(" target is interpreted -- recursive pass\n"); 278 kprintf(" interpreter: %s\n", imgp->interpreter_name); 279 print_execve_args(args); 280 } 281 282 /* 283 * If the current process has a special image activator it 284 * wants to try first, call it. For example, emulating shell 285 * scripts differently. 286 */ 287 error = -1; 288 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 289 error = img_first(imgp); 290 291 /* 292 * If the vnode has a registered vmspace, exec the vmspace 293 */ 294 if (error == -1 && imgp->vp->v_resident) { 295 error = exec_resident_imgact(imgp); 296 } 297 298 /* 299 * Loop through the list of image activators, calling each one. 300 * An activator returns -1 if there is no match, 0 on success, 301 * and an error otherwise. 302 */ 303 for (i = 0; error == -1 && execsw[i]; ++i) { 304 if (execsw[i]->ex_imgact == NULL || 305 execsw[i]->ex_imgact == img_first) { 306 continue; 307 } 308 error = (*execsw[i]->ex_imgact)(imgp); 309 } 310 311 if (error) { 312 if (error == -1) 313 error = ENOEXEC; 314 goto exec_fail_dealloc; 315 } 316 317 /* 318 * Special interpreter operation, cleanup and loop up to try to 319 * activate the interpreter. 320 */ 321 if (imgp->interpreted) { 322 exec_unmap_first_page(imgp); 323 nlookup_done(nd); 324 vrele(imgp->vp); 325 imgp->vp = NULL; 326 error = nlookup_init(nd, imgp->interpreter_name, UIO_SYSSPACE, 327 NLC_FOLLOW); 328 if (error) 329 goto exec_fail; 330 goto interpret; 331 } 332 333 /* 334 * Do the best to calculate the full path to the image file 335 */ 336 if (imgp->auxargs != NULL && 337 ((args->fname != NULL && args->fname[0] == '/') || 338 vn_fullpath(imgp->proc, 339 imgp->vp, 340 &imgp->execpath, 341 &imgp->freepath, 342 0) != 0)) 343 imgp->execpath = args->fname; 344 345 /* 346 * Copy out strings (args and env) and initialize stack base 347 */ 348 stack_base = exec_copyout_strings(imgp); 349 p->p_vmspace->vm_minsaddr = (char *)stack_base; 350 351 /* 352 * If custom stack fixup routine present for this process 353 * let it do the stack setup. If we are running a resident 354 * image there is no auxinfo or other image activator context 355 * so don't try to add fixups to the stack. 356 * 357 * Else stuff argument count as first item on stack 358 */ 359 if (p->p_sysent->sv_fixup && imgp->resident == 0) 360 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 361 else 362 suword(--stack_base, imgp->args->argc); 363 364 /* 365 * For security and other reasons, the file descriptor table cannot 366 * be shared after an exec. 367 */ 368 if (p->p_fd->fd_refcnt > 1) { 369 struct filedesc *tmp; 370 371 error = fdcopy(p, &tmp); 372 if (error != 0) 373 goto exec_fail; 374 fdfree(p, tmp); 375 } 376 377 /* 378 * For security and other reasons, signal handlers cannot 379 * be shared after an exec. The new proces gets a copy of the old 380 * handlers. In execsigs(), the new process will have its signals 381 * reset. 382 */ 383 ops = p->p_sigacts; 384 if (ops->ps_refcnt > 1) { 385 nps = kmalloc(sizeof(*nps), M_SUBPROC, M_WAITOK); 386 bcopy(ops, nps, sizeof(*nps)); 387 refcount_init(&nps->ps_refcnt, 1); 388 p->p_sigacts = nps; 389 if (refcount_release(&ops->ps_refcnt)) { 390 kfree(ops, M_SUBPROC); 391 ops = NULL; 392 } 393 } 394 395 /* 396 * For security and other reasons virtual kernels cannot be 397 * inherited by an exec. This also allows a virtual kernel 398 * to fork/exec unrelated applications. 399 */ 400 if (p->p_vkernel) 401 vkernel_exit(p); 402 403 /* Stop profiling */ 404 stopprofclock(p); 405 406 /* close files on exec */ 407 fdcloseexec(p); 408 409 /* reset caught signals */ 410 execsigs(p); 411 412 /* name this process - nameiexec(p, ndp) */ 413 len = min(nd->nl_nch.ncp->nc_nlen, MAXCOMLEN); 414 bcopy(nd->nl_nch.ncp->nc_name, p->p_comm, len); 415 p->p_comm[len] = 0; 416 bcopy(p->p_comm, lp->lwp_thread->td_comm, MAXCOMLEN+1); 417 418 /* 419 * mark as execed, wakeup the process that vforked (if any) and tell 420 * it that it now has its own resources back 421 * 422 * We are using the P_PPWAIT as an interlock so an atomic op is 423 * necessary to synchronize with the parent's cpu. 424 */ 425 p->p_flags |= P_EXEC; 426 if (p->p_pptr && (p->p_flags & P_PPWAIT)) { 427 if (p->p_pptr->p_upmap) 428 atomic_add_int(&p->p_pptr->p_upmap->invfork, -1); 429 atomic_clear_int(&p->p_flags, P_PPWAIT); 430 wakeup(p->p_pptr); 431 } 432 433 /* 434 * Implement image setuid/setgid. 435 * 436 * Don't honor setuid/setgid if the filesystem prohibits it or if 437 * the process is being traced. 438 */ 439 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 440 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 441 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 442 (p->p_flags & P_TRACED) == 0) { 443 /* 444 * Turn off syscall tracing for set-id programs, except for 445 * root. Record any set-id flags first to make sure that 446 * we do not regain any tracing during a possible block. 447 */ 448 setsugid(); 449 if (p->p_tracenode && ktrace_suid == 0 && 450 priv_check(td, PRIV_ROOT) != 0) { 451 ktrdestroy(&p->p_tracenode); 452 p->p_traceflag = 0; 453 } 454 /* Close any file descriptors 0..2 that reference procfs */ 455 setugidsafety(p); 456 /* Make sure file descriptors 0..2 are in use. */ 457 error = fdcheckstd(lp); 458 if (error != 0) 459 goto exec_fail_dealloc; 460 /* 461 * Set the new credentials. 462 */ 463 cratom_proc(p); 464 if (attr.va_mode & VSUID) 465 change_euid(attr.va_uid); 466 if (attr.va_mode & VSGID) 467 p->p_ucred->cr_gid = attr.va_gid; 468 469 /* 470 * Clear local varsym variables 471 */ 472 varsymset_clean(&p->p_varsymset); 473 } else { 474 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && 475 p->p_ucred->cr_gid == p->p_ucred->cr_rgid) 476 p->p_flags &= ~P_SUGID; 477 } 478 479 /* 480 * Implement correct POSIX saved-id behavior. 481 */ 482 if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || 483 p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { 484 cratom_proc(p); 485 p->p_ucred->cr_svuid = p->p_ucred->cr_uid; 486 p->p_ucred->cr_svgid = p->p_ucred->cr_gid; 487 } 488 489 /* 490 * Store the vp for use in procfs. Be sure to keep p_textvp 491 * consistent if we block during the switch-over. 492 */ 493 ovp = p->p_textvp; 494 vref(imgp->vp); /* ref new vp */ 495 p->p_textvp = imgp->vp; 496 if (ovp) /* release old vp */ 497 vrele(ovp); 498 499 /* Release old namecache handle to text file */ 500 if (p->p_textnch.ncp) 501 cache_drop(&p->p_textnch); 502 503 if (nd->nl_nch.mount) 504 cache_copy(&nd->nl_nch, &p->p_textnch); 505 506 /* 507 * Notify others that we exec'd, and clear the P_INEXEC flag 508 * as we're now a bona fide freshly-execed process. 509 */ 510 KNOTE(&p->p_klist, NOTE_EXEC); 511 p->p_flags &= ~P_INEXEC; 512 if (p->p_stops) 513 wakeup(&p->p_stype); 514 515 /* 516 * If tracing the process, trap to debugger so breakpoints 517 * can be set before the program executes. 518 */ 519 STOPEVENT(p, S_EXEC, 0); 520 521 if (p->p_flags & P_TRACED) 522 ksignal(p, SIGTRAP); 523 524 /* clear "fork but no exec" flag, as we _are_ execing */ 525 p->p_acflag &= ~AFORK; 526 527 /* Set values passed into the program in registers. */ 528 exec_setregs(imgp->entry_addr, (u_long)(uintptr_t)stack_base, 529 imgp->ps_strings); 530 531 /* Set the access time on the vnode */ 532 vn_mark_atime(imgp->vp, td); 533 534 /* 535 * Free any previous argument cache 536 */ 537 pa = p->p_args; 538 p->p_args = NULL; 539 if (pa && refcount_release(&pa->ar_ref)) { 540 kfree(pa, M_PARGS); 541 pa = NULL; 542 } 543 544 /* 545 * Cache arguments if they fit inside our allowance 546 */ 547 i = imgp->args->begin_envv - imgp->args->begin_argv; 548 if (sizeof(struct pargs) + i <= ps_arg_cache_limit) { 549 pa = kmalloc(sizeof(struct pargs) + i, M_PARGS, M_WAITOK); 550 refcount_init(&pa->ar_ref, 1); 551 pa->ar_length = i; 552 bcopy(imgp->args->begin_argv, pa->ar_args, i); 553 KKASSERT(p->p_args == NULL); 554 p->p_args = pa; 555 } 556 557 exec_fail_dealloc: 558 559 /* 560 * free various allocated resources 561 */ 562 if (imgp->firstpage) 563 exec_unmap_first_page(imgp); 564 565 if (imgp->vp) { 566 vrele(imgp->vp); 567 imgp->vp = NULL; 568 } 569 570 if (imgp->freepath) 571 kfree(imgp->freepath, M_TEMP); 572 573 if (error == 0) { 574 ++mycpu->gd_cnt.v_exec; 575 lwkt_reltoken(&p->p_token); 576 return (0); 577 } 578 579 exec_fail: 580 /* 581 * we're done here, clear P_INEXEC if we were the ones that 582 * set it. Otherwise if vmspace_destroyed is still set we 583 * raced another thread and that thread is responsible for 584 * clearing it. 585 */ 586 if (imgp->vmspace_destroyed & 2) { 587 p->p_flags &= ~P_INEXEC; 588 if (p->p_stops) 589 wakeup(&p->p_stype); 590 } 591 lwkt_reltoken(&p->p_token); 592 if (imgp->vmspace_destroyed) { 593 /* 594 * Sorry, no more process anymore. exit gracefully. 595 * However we can't die right here, because our 596 * caller might have to clean up, so indicate a 597 * lethal error by returning -1. 598 */ 599 return(-1); 600 } else { 601 return(error); 602 } 603 } 604 605 /* 606 * execve() system call. 607 */ 608 int 609 sys_execve(struct execve_args *uap) 610 { 611 struct nlookupdata nd; 612 struct image_args args; 613 int error; 614 615 bzero(&args, sizeof(args)); 616 617 error = nlookup_init(&nd, uap->fname, UIO_USERSPACE, NLC_FOLLOW); 618 if (error == 0) { 619 error = exec_copyin_args(&args, uap->fname, PATH_USERSPACE, 620 uap->argv, uap->envv); 621 } 622 if (error == 0) 623 error = kern_execve(&nd, &args); 624 nlookup_done(&nd); 625 exec_free_args(&args); 626 627 if (error < 0) { 628 /* We hit a lethal error condition. Let's die now. */ 629 exit1(W_EXITCODE(0, SIGABRT)); 630 /* NOTREACHED */ 631 } 632 633 /* 634 * The syscall result is returned in registers to the new program. 635 * Linux will register %edx as an atexit function and we must be 636 * sure to set it to 0. XXX 637 */ 638 if (error == 0) 639 uap->sysmsg_result64 = 0; 640 641 return (error); 642 } 643 644 int 645 exec_map_page(struct image_params *imgp, vm_pindex_t pageno, 646 struct lwbuf **plwb, const char **pdata) 647 { 648 int rv; 649 vm_page_t ma; 650 vm_page_t m; 651 vm_object_t object; 652 653 /* 654 * The file has to be mappable. 655 */ 656 if ((object = imgp->vp->v_object) == NULL) 657 return (EIO); 658 659 if (pageno >= object->size) 660 return (EIO); 661 662 /* 663 * Shortcut using shared locks, improve concurrent execs. 664 */ 665 vm_object_hold_shared(object); 666 m = vm_page_lookup(object, pageno); 667 if (m) { 668 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) { 669 vm_page_hold(m); 670 vm_page_sleep_busy(m, FALSE, "execpg"); 671 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL && 672 m->object == object && m->pindex == pageno) { 673 vm_object_drop(object); 674 goto done; 675 } 676 vm_page_unhold(m); 677 } 678 } 679 vm_object_drop(object); 680 681 /* 682 * Do it the hard way 683 */ 684 vm_object_hold(object); 685 m = vm_page_grab(object, pageno, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 686 while ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 687 ma = m; 688 689 /* 690 * get_pages unbusies all the requested pages except the 691 * primary page (at index 0 in this case). The primary 692 * page may have been wired during the pagein (e.g. by 693 * the buffer cache) so vnode_pager_freepage() must be 694 * used to properly release it. 695 */ 696 rv = vm_pager_get_page(object, &ma, 1); 697 m = vm_page_lookup(object, pageno); 698 699 if (rv != VM_PAGER_OK || m == NULL || m->valid == 0) { 700 if (m) { 701 vm_page_protect(m, VM_PROT_NONE); 702 vnode_pager_freepage(m); 703 } 704 vm_object_drop(object); 705 return EIO; 706 } 707 } 708 vm_page_hold(m); 709 vm_page_wakeup(m); /* unbusy the page */ 710 vm_object_drop(object); 711 712 done: 713 *plwb = lwbuf_alloc(m, *plwb); 714 *pdata = (void *)lwbuf_kva(*plwb); 715 716 return (0); 717 } 718 719 /* 720 * Map the first page of an executable image. 721 * 722 * NOTE: If the mapping fails we have to NULL-out firstpage which may 723 * still be pointing to our supplied lwp structure. 724 */ 725 int 726 exec_map_first_page(struct image_params *imgp) 727 { 728 int err; 729 730 if (imgp->firstpage) 731 exec_unmap_first_page(imgp); 732 733 imgp->firstpage = &imgp->firstpage_cache; 734 err = exec_map_page(imgp, 0, &imgp->firstpage, &imgp->image_header); 735 736 if (err) { 737 imgp->firstpage = NULL; 738 return err; 739 } 740 741 return 0; 742 } 743 744 void 745 exec_unmap_page(struct lwbuf *lwb) 746 { 747 vm_page_t m; 748 749 crit_enter(); 750 if (lwb != NULL) { 751 m = lwbuf_page(lwb); 752 lwbuf_free(lwb); 753 vm_page_unhold(m); 754 } 755 crit_exit(); 756 } 757 758 void 759 exec_unmap_first_page(struct image_params *imgp) 760 { 761 exec_unmap_page(imgp->firstpage); 762 imgp->firstpage = NULL; 763 imgp->image_header = NULL; 764 } 765 766 /* 767 * Destroy old address space, and allocate a new stack 768 * The new stack is only SGROWSIZ large because it is grown 769 * automatically in trap.c. 770 * 771 * This is the point of no return. 772 */ 773 int 774 exec_new_vmspace(struct image_params *imgp, struct vmspace *vmcopy) 775 { 776 struct vmspace *vmspace = imgp->proc->p_vmspace; 777 vm_offset_t stack_addr = USRSTACK - maxssiz; 778 struct proc *p; 779 vm_map_t map; 780 int error; 781 782 /* 783 * Indicate that we cannot gracefully error out any more, kill 784 * any other threads present, and set P_INEXEC to indicate that 785 * we are now messing with the process structure proper. 786 * 787 * If killalllwps() races return an error which coupled with 788 * vmspace_destroyed will cause us to exit. This is what we 789 * want since another thread is patiently waiting for us to exit 790 * in that case. 791 */ 792 p = curproc; 793 imgp->vmspace_destroyed = 1; 794 795 if (curthread->td_proc->p_nthreads > 1) { 796 error = killalllwps(1); 797 if (error) 798 return (error); 799 } 800 imgp->vmspace_destroyed |= 2; /* we are responsible for P_INEXEC */ 801 p->p_flags |= P_INEXEC; 802 803 /* 804 * Tell procfs to release its hold on the process. It 805 * will return EAGAIN. 806 */ 807 if (p->p_stops) 808 wakeup(&p->p_stype); 809 810 /* 811 * After setting P_INEXEC wait for any remaining references to 812 * the process (p) to go away. 813 * 814 * In particular, a vfork/exec sequence will replace p->p_vmspace 815 * and we must interlock anyone trying to access the space (aka 816 * procfs or sys_process.c calling procfs_domem()). 817 * 818 * If P_PPWAIT is set the parent vfork()'d and has a PHOLD() on us. 819 */ 820 PSTALL(p, "exec1", ((p->p_flags & P_PPWAIT) ? 1 : 0)); 821 822 /* 823 * Blow away entire process VM, if address space not shared, 824 * otherwise, create a new VM space so that other threads are 825 * not disrupted. If we are execing a resident vmspace we 826 * create a duplicate of it and remap the stack. 827 */ 828 map = &vmspace->vm_map; 829 if (vmcopy) { 830 vmspace_exec(imgp->proc, vmcopy); 831 vmspace = imgp->proc->p_vmspace; 832 pmap_remove_pages(vmspace_pmap(vmspace), stack_addr, USRSTACK); 833 map = &vmspace->vm_map; 834 } else if (vmspace_getrefs(vmspace) == 1) { 835 shmexit(vmspace); 836 pmap_remove_pages(vmspace_pmap(vmspace), 837 0, VM_MAX_USER_ADDRESS); 838 vm_map_remove(map, 0, VM_MAX_USER_ADDRESS); 839 } else { 840 vmspace_exec(imgp->proc, NULL); 841 vmspace = imgp->proc->p_vmspace; 842 map = &vmspace->vm_map; 843 } 844 845 /* Allocate a new stack */ 846 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 847 0, VM_PROT_ALL, VM_PROT_ALL, 0); 848 if (error) 849 return (error); 850 851 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 852 * VM_STACK case, but they are still used to monitor the size of the 853 * process stack so we can check the stack rlimit. 854 */ 855 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 856 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 857 858 return(0); 859 } 860 861 /* 862 * Copy out argument and environment strings from the old process 863 * address space into the temporary string buffer. 864 */ 865 int 866 exec_copyin_args(struct image_args *args, char *fname, 867 enum exec_path_segflg segflg, char **argv, char **envv) 868 { 869 char *argp, *envp; 870 int error = 0; 871 size_t length; 872 873 args->buf = objcache_get(exec_objcache, M_WAITOK); 874 if (args->buf == NULL) 875 return (ENOMEM); 876 args->begin_argv = args->buf; 877 args->endp = args->begin_argv; 878 args->space = ARG_MAX; 879 880 args->fname = args->buf + ARG_MAX; 881 882 /* 883 * Copy the file name. 884 */ 885 if (segflg == PATH_SYSSPACE) { 886 error = copystr(fname, args->fname, PATH_MAX, &length); 887 } else if (segflg == PATH_USERSPACE) { 888 error = copyinstr(fname, args->fname, PATH_MAX, &length); 889 } 890 891 /* 892 * Extract argument strings. argv may not be NULL. The argv 893 * array is terminated by a NULL entry. We special-case the 894 * situation where argv[0] is NULL by passing { filename, NULL } 895 * to the new program to guarentee that the interpreter knows what 896 * file to open in case we exec an interpreted file. Note that 897 * a NULL argv[0] terminates the argv[] array. 898 * 899 * XXX the special-casing of argv[0] is historical and needs to be 900 * revisited. 901 */ 902 if (argv == NULL) 903 error = EFAULT; 904 if (error == 0) { 905 while ((argp = (caddr_t)(intptr_t)fuword(argv++)) != NULL) { 906 if (argp == (caddr_t)-1) { 907 error = EFAULT; 908 break; 909 } 910 error = copyinstr(argp, args->endp, 911 args->space, &length); 912 if (error) { 913 if (error == ENAMETOOLONG) 914 error = E2BIG; 915 break; 916 } 917 args->space -= length; 918 args->endp += length; 919 args->argc++; 920 } 921 if (args->argc == 0 && error == 0) { 922 length = strlen(args->fname) + 1; 923 if (length > args->space) { 924 error = E2BIG; 925 } else { 926 bcopy(args->fname, args->endp, length); 927 args->space -= length; 928 args->endp += length; 929 args->argc++; 930 } 931 } 932 } 933 934 args->begin_envv = args->endp; 935 936 /* 937 * extract environment strings. envv may be NULL. 938 */ 939 if (envv && error == 0) { 940 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 941 if (envp == (caddr_t) -1) { 942 error = EFAULT; 943 break; 944 } 945 error = copyinstr(envp, args->endp, 946 args->space, &length); 947 if (error) { 948 if (error == ENAMETOOLONG) 949 error = E2BIG; 950 break; 951 } 952 args->space -= length; 953 args->endp += length; 954 args->envc++; 955 } 956 } 957 return (error); 958 } 959 960 void 961 exec_free_args(struct image_args *args) 962 { 963 if (args->buf) { 964 objcache_put(exec_objcache, args->buf); 965 args->buf = NULL; 966 } 967 } 968 969 /* 970 * Copy strings out to the new process address space, constructing 971 * new arg and env vector tables. Return a pointer to the base 972 * so that it can be used as the initial stack pointer. 973 * 974 * The format is, roughly: 975 * 976 * [argv[]] <-- vectp 977 * [envp[]] 978 * [ELF_Auxargs] 979 * 980 * [args & env] <-- destp 981 * [sgap] 982 * [SPARE_USRSPACE] 983 * [execpath] 984 * [szsigcode] 985 * [ps_strings] top of user stack 986 * 987 */ 988 static register_t * 989 exec_copyout_strings(struct image_params *imgp) 990 { 991 int argc, envc, sgap; 992 int gap; 993 int argsenvspace; 994 char **vectp; 995 char *stringp, *destp; 996 register_t *stack_base; 997 struct ps_strings *arginfo; 998 size_t execpath_len; 999 int szsigcode; 1000 1001 /* 1002 * Calculate string base and vector table pointers. 1003 * Also deal with signal trampoline code for this exec type. 1004 */ 1005 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1006 execpath_len = strlen(imgp->execpath) + 1; 1007 else 1008 execpath_len = 0; 1009 arginfo = (struct ps_strings *)PS_STRINGS; 1010 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 1011 1012 argsenvspace = roundup((ARG_MAX - imgp->args->space), sizeof(char *)); 1013 gap = stackgap_random; 1014 cpu_ccfence(); 1015 if (gap != 0) { 1016 if (gap < 0) 1017 sgap = ALIGN(-gap); 1018 else 1019 sgap = ALIGN(karc4random() & (gap - 1)); 1020 } else { 1021 sgap = 0; 1022 } 1023 1024 /* 1025 * Calculate destp, which points to [args & env] and above. 1026 */ 1027 destp = (caddr_t)arginfo - 1028 szsigcode - 1029 roundup(execpath_len, sizeof(char *)) - 1030 SPARE_USRSPACE - 1031 sgap - 1032 argsenvspace; 1033 1034 /* 1035 * install sigcode 1036 */ 1037 if (szsigcode) { 1038 copyout(imgp->proc->p_sysent->sv_sigcode, 1039 ((caddr_t)arginfo - szsigcode), szsigcode); 1040 } 1041 1042 /* 1043 * Copy the image path for the rtld 1044 */ 1045 if (execpath_len) { 1046 imgp->execpathp = (uintptr_t)arginfo 1047 - szsigcode 1048 - roundup(execpath_len, sizeof(char *)); 1049 copyout(imgp->execpath, (void *)imgp->execpathp, execpath_len); 1050 } 1051 1052 /* 1053 * Calculate base for argv[], envp[], and ELF_Auxargs. 1054 */ 1055 vectp = (char **)destp - (AT_COUNT * 2); 1056 vectp -= imgp->args->argc + imgp->args->envc + 2; 1057 1058 stack_base = (register_t *)vectp; 1059 1060 stringp = imgp->args->begin_argv; 1061 argc = imgp->args->argc; 1062 envc = imgp->args->envc; 1063 1064 /* 1065 * Copy out strings - arguments and environment (at destp) 1066 */ 1067 copyout(stringp, destp, ARG_MAX - imgp->args->space); 1068 1069 /* 1070 * Fill in "ps_strings" struct for ps, w, etc. 1071 */ 1072 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1073 suword32(&arginfo->ps_nargvstr, argc); 1074 1075 /* 1076 * Fill in argument portion of vector table. 1077 */ 1078 for (; argc > 0; --argc) { 1079 suword(vectp++, (long)(intptr_t)destp); 1080 while (*stringp++ != 0) 1081 destp++; 1082 destp++; 1083 } 1084 1085 /* a null vector table pointer separates the argp's from the envp's */ 1086 suword(vectp++, 0); 1087 1088 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1089 suword32(&arginfo->ps_nenvstr, envc); 1090 1091 /* 1092 * Fill in environment portion of vector table. 1093 */ 1094 for (; envc > 0; --envc) { 1095 suword(vectp++, (long)(intptr_t)destp); 1096 while (*stringp++ != 0) 1097 destp++; 1098 destp++; 1099 } 1100 1101 /* end of vector table is a null pointer */ 1102 suword(vectp, 0); 1103 1104 return (stack_base); 1105 } 1106 1107 /* 1108 * Check permissions of file to execute. 1109 * Return 0 for success or error code on failure. 1110 */ 1111 int 1112 exec_check_permissions(struct image_params *imgp, struct mount *topmnt) 1113 { 1114 struct proc *p = imgp->proc; 1115 struct vnode *vp = imgp->vp; 1116 struct vattr *attr = imgp->attr; 1117 int error; 1118 1119 /* Get file attributes */ 1120 error = VOP_GETATTR(vp, attr); 1121 if (error) 1122 return (error); 1123 1124 /* 1125 * 1) Check if file execution is disabled for the filesystem that this 1126 * file resides on. 1127 * 2) Insure that at least one execute bit is on - otherwise root 1128 * will always succeed, and we don't want to happen unless the 1129 * file really is executable. 1130 * 3) Insure that the file is a regular file. 1131 */ 1132 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1133 ((topmnt != NULL) && (topmnt->mnt_flag & MNT_NOEXEC)) || 1134 ((attr->va_mode & 0111) == 0) || 1135 (attr->va_type != VREG)) { 1136 return (EACCES); 1137 } 1138 1139 /* 1140 * Zero length files can't be exec'd 1141 */ 1142 if (attr->va_size == 0) 1143 return (ENOEXEC); 1144 1145 /* 1146 * Check for execute permission to file based on current credentials. 1147 */ 1148 error = VOP_EACCESS(vp, VEXEC, p->p_ucred); 1149 if (error) 1150 return (error); 1151 1152 /* 1153 * Check number of open-for-writes on the file and deny execution 1154 * if there are any. 1155 */ 1156 if (vp->v_writecount) 1157 return (ETXTBSY); 1158 1159 /* 1160 * Call filesystem specific open routine, which allows us to read, 1161 * write, and mmap the file. Without the VOP_OPEN we can only 1162 * stat the file. 1163 */ 1164 error = VOP_OPEN(vp, FREAD, p->p_ucred, NULL); 1165 if (error) 1166 return (error); 1167 1168 return (0); 1169 } 1170 1171 /* 1172 * Exec handler registration 1173 */ 1174 int 1175 exec_register(const struct execsw *execsw_arg) 1176 { 1177 const struct execsw **es, **xs, **newexecsw; 1178 int count = 2; /* New slot and trailing NULL */ 1179 1180 if (execsw) 1181 for (es = execsw; *es; es++) 1182 count++; 1183 newexecsw = kmalloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1184 xs = newexecsw; 1185 if (execsw) 1186 for (es = execsw; *es; es++) 1187 *xs++ = *es; 1188 *xs++ = execsw_arg; 1189 *xs = NULL; 1190 if (execsw) 1191 kfree(execsw, M_TEMP); 1192 execsw = newexecsw; 1193 return 0; 1194 } 1195 1196 int 1197 exec_unregister(const struct execsw *execsw_arg) 1198 { 1199 const struct execsw **es, **xs, **newexecsw; 1200 int count = 1; 1201 1202 if (execsw == NULL) 1203 panic("unregister with no handlers left?"); 1204 1205 for (es = execsw; *es; es++) { 1206 if (*es == execsw_arg) 1207 break; 1208 } 1209 if (*es == NULL) 1210 return ENOENT; 1211 for (es = execsw; *es; es++) 1212 if (*es != execsw_arg) 1213 count++; 1214 newexecsw = kmalloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1215 xs = newexecsw; 1216 for (es = execsw; *es; es++) 1217 if (*es != execsw_arg) 1218 *xs++ = *es; 1219 *xs = NULL; 1220 if (execsw) 1221 kfree(execsw, M_TEMP); 1222 execsw = newexecsw; 1223 return 0; 1224 } 1225