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 77 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 78 MALLOC_DEFINE(M_EXECARGS, "exec-args", "Exec arguments"); 79 80 static register_t *exec_copyout_strings (struct image_params *); 81 82 /* XXX This should be vm_size_t. */ 83 static u_long ps_strings = PS_STRINGS; 84 SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, ""); 85 86 /* XXX This should be vm_size_t. */ 87 static u_long usrstack = USRSTACK; 88 SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, ""); 89 90 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 91 SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 92 &ps_arg_cache_limit, 0, ""); 93 94 int ps_argsopen = 1; 95 SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, ""); 96 97 static int ktrace_suid = 0; 98 SYSCTL_INT(_kern, OID_AUTO, ktrace_suid, CTLFLAG_RW, &ktrace_suid, 0, ""); 99 100 void print_execve_args(struct image_args *args); 101 int debug_execve_args = 0; 102 SYSCTL_INT(_kern, OID_AUTO, debug_execve_args, CTLFLAG_RW, &debug_execve_args, 103 0, ""); 104 105 /* 106 * Exec arguments object cache 107 */ 108 static struct objcache *exec_objcache; 109 110 static 111 void 112 exec_objcache_init(void *arg __unused) 113 { 114 int cluster_limit; 115 116 cluster_limit = 16; /* up to this many objects */ 117 exec_objcache = objcache_create_mbacked( 118 M_EXECARGS, PATH_MAX + ARG_MAX, 119 &cluster_limit, 8, 120 NULL, NULL, NULL); 121 } 122 SYSINIT(exec_objcache, SI_BOOT2_MACHDEP, SI_ORDER_ANY, exec_objcache_init, 0); 123 124 /* 125 * stackgap_random specifies if the stackgap should have a random size added 126 * to it. It must be a power of 2. If non-zero, the stack gap will be 127 * calculated as: ALIGN(karc4random() & (stackgap_random - 1)). 128 */ 129 static int stackgap_random = 1024; 130 static int 131 sysctl_kern_stackgap(SYSCTL_HANDLER_ARGS) 132 { 133 int error, new_val; 134 new_val = stackgap_random; 135 error = sysctl_handle_int(oidp, &new_val, 0, req); 136 if (error != 0 || req->newptr == NULL) 137 return (error); 138 if ((new_val < 0) || (new_val > 16 * PAGE_SIZE) || ! powerof2(new_val)) 139 return (EINVAL); 140 stackgap_random = new_val; 141 142 return(0); 143 } 144 145 SYSCTL_PROC(_kern, OID_AUTO, stackgap_random, CTLFLAG_RW|CTLTYPE_UINT, 146 0, 0, sysctl_kern_stackgap, "IU", "Max random stack gap (power of 2)"); 147 148 void 149 print_execve_args(struct image_args *args) 150 { 151 char *cp; 152 int ndx; 153 154 cp = args->begin_argv; 155 for (ndx = 0; ndx < args->argc; ndx++) { 156 kprintf("\targv[%d]: %s\n", ndx, cp); 157 while (*cp++ != '\0'); 158 } 159 for (ndx = 0; ndx < args->envc; ndx++) { 160 kprintf("\tenvv[%d]: %s\n", ndx, cp); 161 while (*cp++ != '\0'); 162 } 163 } 164 165 /* 166 * Each of the items is a pointer to a `const struct execsw', hence the 167 * double pointer here. 168 */ 169 static const struct execsw **execsw; 170 171 /* 172 * Replace current vmspace with a new binary. 173 * Returns 0 on success, > 0 on recoverable error (use as errno). 174 * Returns -1 on lethal error which demands killing of the current 175 * process! 176 */ 177 int 178 kern_execve(struct nlookupdata *nd, struct image_args *args) 179 { 180 struct thread *td = curthread; 181 struct lwp *lp = td->td_lwp; 182 struct proc *p = td->td_proc; 183 register_t *stack_base; 184 struct pargs *pa; 185 struct sigacts *ops; 186 struct sigacts *nps; 187 int error, len, i; 188 struct image_params image_params, *imgp; 189 struct vattr attr; 190 int (*img_first) (struct image_params *); 191 192 if (debug_execve_args) { 193 kprintf("%s()\n", __func__); 194 print_execve_args(args); 195 } 196 197 KKASSERT(p); 198 lwkt_gettoken(&p->p_token); 199 imgp = &image_params; 200 201 /* 202 * NOTE: P_INEXEC is handled by exec_new_vmspace() now. We make 203 * no modifications to the process at all until we get there. 204 * 205 * Note that multiple threads may be trying to exec at the same 206 * time. exec_new_vmspace() handles that too. 207 */ 208 209 /* 210 * Initialize part of the common data 211 */ 212 imgp->proc = p; 213 imgp->args = args; 214 imgp->attr = &attr; 215 imgp->entry_addr = 0; 216 imgp->resident = 0; 217 imgp->vmspace_destroyed = 0; 218 imgp->interpreted = 0; 219 imgp->interpreter_name[0] = 0; 220 imgp->auxargs = NULL; 221 imgp->vp = NULL; 222 imgp->firstpage = NULL; 223 imgp->ps_strings = 0; 224 imgp->execpath = imgp->freepath = NULL; 225 imgp->execpathp = 0; 226 imgp->image_header = NULL; 227 228 interpret: 229 230 /* 231 * Translate the file name to a vnode. Unlock the cache entry to 232 * improve parallelism for programs exec'd in parallel. 233 */ 234 if ((error = nlookup(nd)) != 0) 235 goto exec_fail; 236 error = cache_vget(&nd->nl_nch, nd->nl_cred, LK_EXCLUSIVE, &imgp->vp); 237 KKASSERT(nd->nl_flags & NLC_NCPISLOCKED); 238 nd->nl_flags &= ~NLC_NCPISLOCKED; 239 cache_unlock(&nd->nl_nch); 240 if (error) 241 goto exec_fail; 242 243 /* 244 * Check file permissions (also 'opens' file). 245 * Include also the top level mount in the check. 246 */ 247 error = exec_check_permissions(imgp, nd->nl_nch.mount); 248 if (error) { 249 vn_unlock(imgp->vp); 250 goto exec_fail_dealloc; 251 } 252 253 error = exec_map_first_page(imgp); 254 vn_unlock(imgp->vp); 255 if (error) 256 goto exec_fail_dealloc; 257 258 imgp->proc->p_osrel = 0; 259 260 if (debug_execve_args && imgp->interpreted) { 261 kprintf(" target is interpreted -- recursive pass\n"); 262 kprintf(" interpreter: %s\n", imgp->interpreter_name); 263 print_execve_args(args); 264 } 265 266 /* 267 * If the current process has a special image activator it 268 * wants to try first, call it. For example, emulating shell 269 * scripts differently. 270 */ 271 error = -1; 272 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 273 error = img_first(imgp); 274 275 /* 276 * If the vnode has a registered vmspace, exec the vmspace 277 */ 278 if (error == -1 && imgp->vp->v_resident) { 279 error = exec_resident_imgact(imgp); 280 } 281 282 /* 283 * Loop through the list of image activators, calling each one. 284 * An activator returns -1 if there is no match, 0 on success, 285 * and an error otherwise. 286 */ 287 for (i = 0; error == -1 && execsw[i]; ++i) { 288 if (execsw[i]->ex_imgact == NULL || 289 execsw[i]->ex_imgact == img_first) { 290 continue; 291 } 292 error = (*execsw[i]->ex_imgact)(imgp); 293 } 294 295 if (error) { 296 if (error == -1) 297 error = ENOEXEC; 298 goto exec_fail_dealloc; 299 } 300 301 /* 302 * Special interpreter operation, cleanup and loop up to try to 303 * activate the interpreter. 304 */ 305 if (imgp->interpreted) { 306 exec_unmap_first_page(imgp); 307 nlookup_done(nd); 308 vrele(imgp->vp); 309 imgp->vp = NULL; 310 error = nlookup_init(nd, imgp->interpreter_name, UIO_SYSSPACE, 311 NLC_FOLLOW); 312 if (error) 313 goto exec_fail; 314 goto interpret; 315 } 316 317 /* 318 * Do the best to calculate the full path to the image file 319 */ 320 if (imgp->auxargs != NULL && 321 ((args->fname != NULL && args->fname[0] == '/') || 322 vn_fullpath(imgp->proc, 323 imgp->vp, 324 &imgp->execpath, 325 &imgp->freepath, 326 0) != 0)) 327 imgp->execpath = args->fname; 328 329 /* 330 * Copy out strings (args and env) and initialize stack base 331 */ 332 stack_base = exec_copyout_strings(imgp); 333 p->p_vmspace->vm_minsaddr = (char *)stack_base; 334 335 /* 336 * If custom stack fixup routine present for this process 337 * let it do the stack setup. If we are running a resident 338 * image there is no auxinfo or other image activator context 339 * so don't try to add fixups to the stack. 340 * 341 * Else stuff argument count as first item on stack 342 */ 343 if (p->p_sysent->sv_fixup && imgp->resident == 0) 344 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 345 else 346 suword(--stack_base, imgp->args->argc); 347 348 /* 349 * For security and other reasons, the file descriptor table cannot 350 * be shared after an exec. 351 */ 352 if (p->p_fd->fd_refcnt > 1) { 353 struct filedesc *tmp; 354 355 error = fdcopy(p, &tmp); 356 if (error != 0) 357 goto exec_fail; 358 fdfree(p, tmp); 359 } 360 361 /* 362 * For security and other reasons, signal handlers cannot 363 * be shared after an exec. The new proces gets a copy of the old 364 * handlers. In execsigs(), the new process will have its signals 365 * reset. 366 */ 367 ops = p->p_sigacts; 368 if (ops->ps_refcnt > 1) { 369 nps = kmalloc(sizeof(*nps), M_SUBPROC, M_WAITOK); 370 bcopy(ops, nps, sizeof(*nps)); 371 refcount_init(&nps->ps_refcnt, 1); 372 p->p_sigacts = nps; 373 if (refcount_release(&ops->ps_refcnt)) { 374 kfree(ops, M_SUBPROC); 375 ops = NULL; 376 } 377 } 378 379 /* 380 * For security and other reasons virtual kernels cannot be 381 * inherited by an exec. This also allows a virtual kernel 382 * to fork/exec unrelated applications. 383 */ 384 if (p->p_vkernel) 385 vkernel_exit(p); 386 387 /* Stop profiling */ 388 stopprofclock(p); 389 390 /* close files on exec */ 391 fdcloseexec(p); 392 393 /* reset caught signals */ 394 execsigs(p); 395 396 /* name this process - nameiexec(p, ndp) */ 397 len = min(nd->nl_nch.ncp->nc_nlen, MAXCOMLEN); 398 bcopy(nd->nl_nch.ncp->nc_name, p->p_comm, len); 399 p->p_comm[len] = 0; 400 bcopy(p->p_comm, lp->lwp_thread->td_comm, MAXCOMLEN+1); 401 402 /* 403 * mark as execed, wakeup the process that vforked (if any) and tell 404 * it that it now has its own resources back 405 */ 406 p->p_flag |= P_EXEC; 407 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 408 p->p_flag &= ~P_PPWAIT; 409 wakeup((caddr_t)p->p_pptr); 410 } 411 412 /* 413 * Implement image setuid/setgid. 414 * 415 * Don't honor setuid/setgid if the filesystem prohibits it or if 416 * the process is being traced. 417 */ 418 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 419 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 420 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 421 (p->p_flag & P_TRACED) == 0) { 422 /* 423 * Turn off syscall tracing for set-id programs, except for 424 * root. Record any set-id flags first to make sure that 425 * we do not regain any tracing during a possible block. 426 */ 427 setsugid(); 428 if (p->p_tracenode && ktrace_suid == 0 && 429 priv_check(td, PRIV_ROOT) != 0) { 430 ktrdestroy(&p->p_tracenode); 431 p->p_traceflag = 0; 432 } 433 /* Close any file descriptors 0..2 that reference procfs */ 434 setugidsafety(p); 435 /* Make sure file descriptors 0..2 are in use. */ 436 error = fdcheckstd(lp); 437 if (error != 0) 438 goto exec_fail_dealloc; 439 /* 440 * Set the new credentials. 441 */ 442 cratom(&p->p_ucred); 443 if (attr.va_mode & VSUID) 444 change_euid(attr.va_uid); 445 if (attr.va_mode & VSGID) 446 p->p_ucred->cr_gid = attr.va_gid; 447 448 /* 449 * Clear local varsym variables 450 */ 451 varsymset_clean(&p->p_varsymset); 452 } else { 453 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && 454 p->p_ucred->cr_gid == p->p_ucred->cr_rgid) 455 p->p_flag &= ~P_SUGID; 456 } 457 458 /* 459 * Implement correct POSIX saved-id behavior. 460 */ 461 if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || 462 p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { 463 cratom(&p->p_ucred); 464 p->p_ucred->cr_svuid = p->p_ucred->cr_uid; 465 p->p_ucred->cr_svgid = p->p_ucred->cr_gid; 466 } 467 468 /* 469 * Store the vp for use in procfs 470 */ 471 if (p->p_textvp) /* release old reference */ 472 vrele(p->p_textvp); 473 p->p_textvp = imgp->vp; 474 vref(p->p_textvp); 475 476 /* Release old namecache handle to text file */ 477 if (p->p_textnch.ncp) 478 cache_drop(&p->p_textnch); 479 480 if (nd->nl_nch.mount) 481 cache_copy(&nd->nl_nch, &p->p_textnch); 482 483 /* 484 * Notify others that we exec'd, and clear the P_INEXEC flag 485 * as we're now a bona fide freshly-execed process. 486 */ 487 KNOTE(&p->p_klist, NOTE_EXEC); 488 p->p_flag &= ~P_INEXEC; 489 490 /* 491 * If tracing the process, trap to debugger so breakpoints 492 * can be set before the program executes. 493 */ 494 STOPEVENT(p, S_EXEC, 0); 495 496 if (p->p_flag & P_TRACED) 497 ksignal(p, SIGTRAP); 498 499 /* clear "fork but no exec" flag, as we _are_ execing */ 500 p->p_acflag &= ~AFORK; 501 502 /* Set values passed into the program in registers. */ 503 exec_setregs(imgp->entry_addr, (u_long)(uintptr_t)stack_base, 504 imgp->ps_strings); 505 506 /* Set the access time on the vnode */ 507 vn_mark_atime(imgp->vp, td); 508 509 /* 510 * Free any previous argument cache 511 */ 512 pa = p->p_args; 513 p->p_args = NULL; 514 if (pa && refcount_release(&pa->ar_ref)) { 515 kfree(pa, M_PARGS); 516 pa = NULL; 517 } 518 519 /* 520 * Cache arguments if they fit inside our allowance 521 */ 522 i = imgp->args->begin_envv - imgp->args->begin_argv; 523 if (sizeof(struct pargs) + i <= ps_arg_cache_limit) { 524 pa = kmalloc(sizeof(struct pargs) + i, M_PARGS, M_WAITOK); 525 refcount_init(&pa->ar_ref, 1); 526 pa->ar_length = i; 527 bcopy(imgp->args->begin_argv, pa->ar_args, i); 528 KKASSERT(p->p_args == NULL); 529 p->p_args = pa; 530 } 531 532 exec_fail_dealloc: 533 534 /* 535 * free various allocated resources 536 */ 537 if (imgp->firstpage) 538 exec_unmap_first_page(imgp); 539 540 if (imgp->vp) { 541 vrele(imgp->vp); 542 imgp->vp = NULL; 543 } 544 545 if (error == 0) { 546 ++mycpu->gd_cnt.v_exec; 547 lwkt_reltoken(&p->p_token); 548 return (0); 549 } 550 551 if (imgp->freepath) 552 kfree(imgp->freepath, M_TEMP); 553 554 exec_fail: 555 /* 556 * we're done here, clear P_INEXEC if we were the ones that 557 * set it. Otherwise if vmspace_destroyed is still set we 558 * raced another thread and that thread is responsible for 559 * clearing it. 560 */ 561 if (imgp->vmspace_destroyed & 2) 562 p->p_flag &= ~P_INEXEC; 563 lwkt_reltoken(&p->p_token); 564 if (imgp->vmspace_destroyed) { 565 /* 566 * Sorry, no more process anymore. exit gracefully. 567 * However we can't die right here, because our 568 * caller might have to clean up, so indicate a 569 * lethal error by returning -1. 570 */ 571 return(-1); 572 } else { 573 return(error); 574 } 575 } 576 577 /* 578 * execve() system call. 579 * 580 * MPALMOSTSAFE 581 */ 582 int 583 sys_execve(struct execve_args *uap) 584 { 585 struct nlookupdata nd; 586 struct image_args args; 587 int error; 588 589 bzero(&args, sizeof(args)); 590 591 get_mplock(); 592 error = nlookup_init(&nd, uap->fname, UIO_USERSPACE, NLC_FOLLOW); 593 if (error == 0) { 594 error = exec_copyin_args(&args, uap->fname, PATH_USERSPACE, 595 uap->argv, uap->envv); 596 } 597 if (error == 0) 598 error = kern_execve(&nd, &args); 599 nlookup_done(&nd); 600 exec_free_args(&args); 601 602 if (error < 0) { 603 /* We hit a lethal error condition. Let's die now. */ 604 exit1(W_EXITCODE(0, SIGABRT)); 605 /* NOTREACHED */ 606 } 607 rel_mplock(); 608 609 /* 610 * The syscall result is returned in registers to the new program. 611 * Linux will register %edx as an atexit function and we must be 612 * sure to set it to 0. XXX 613 */ 614 if (error == 0) 615 uap->sysmsg_result64 = 0; 616 617 return (error); 618 } 619 620 int 621 exec_map_page(struct image_params *imgp, vm_pindex_t pageno, 622 struct lwbuf **plwb, const char **pdata) 623 { 624 int rv; 625 vm_page_t ma; 626 vm_page_t m; 627 vm_object_t object; 628 629 /* 630 * The file has to be mappable. 631 */ 632 if ((object = imgp->vp->v_object) == NULL) 633 return (EIO); 634 635 if (pageno >= object->size) 636 return (EIO); 637 638 m = vm_page_grab(object, pageno, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 639 640 lwkt_gettoken(&vm_token); 641 while ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 642 ma = m; 643 644 /* 645 * get_pages unbusies all the requested pages except the 646 * primary page (at index 0 in this case). The primary 647 * page may have been wired during the pagein (e.g. by 648 * the buffer cache) so vnode_pager_freepage() must be 649 * used to properly release it. 650 */ 651 rv = vm_pager_get_page(object, &ma, 1); 652 m = vm_page_lookup(object, pageno); 653 654 if (rv != VM_PAGER_OK || m == NULL || m->valid == 0) { 655 if (m) { 656 vm_page_protect(m, VM_PROT_NONE); 657 vnode_pager_freepage(m); 658 } 659 lwkt_reltoken(&vm_token); 660 return EIO; 661 } 662 } 663 vm_page_hold(m); /* requires vm_token to be held */ 664 vm_page_wakeup(m); /* unbusy the page */ 665 lwkt_reltoken(&vm_token); 666 667 *plwb = lwbuf_alloc(m, *plwb); 668 *pdata = (void *)lwbuf_kva(*plwb); 669 670 return (0); 671 } 672 673 int 674 exec_map_first_page(struct image_params *imgp) 675 { 676 int err; 677 678 if (imgp->firstpage) 679 exec_unmap_first_page(imgp); 680 681 imgp->firstpage = &imgp->firstpage_cache; 682 err = exec_map_page(imgp, 0, &imgp->firstpage, &imgp->image_header); 683 684 if (err) 685 return err; 686 687 return 0; 688 } 689 690 void 691 exec_unmap_page(struct lwbuf *lwb) 692 { 693 vm_page_t m; 694 695 crit_enter(); 696 if (lwb != NULL) { 697 m = lwbuf_page(lwb); 698 lwbuf_free(lwb); 699 vm_page_unhold(m); 700 } 701 crit_exit(); 702 } 703 704 void 705 exec_unmap_first_page(struct image_params *imgp) 706 { 707 exec_unmap_page(imgp->firstpage); 708 imgp->firstpage = NULL; 709 imgp->image_header = NULL; 710 } 711 712 /* 713 * Destroy old address space, and allocate a new stack 714 * The new stack is only SGROWSIZ large because it is grown 715 * automatically in trap.c. 716 * 717 * This is the point of no return. 718 */ 719 int 720 exec_new_vmspace(struct image_params *imgp, struct vmspace *vmcopy) 721 { 722 struct vmspace *vmspace = imgp->proc->p_vmspace; 723 vm_offset_t stack_addr = USRSTACK - maxssiz; 724 struct proc *p; 725 vm_map_t map; 726 int error; 727 728 /* 729 * Indicate that we cannot gracefully error out any more, kill 730 * any other threads present, and set P_INEXEC to indicate that 731 * we are now messing with the process structure proper. 732 * 733 * If killalllwps() races return an error which coupled with 734 * vmspace_destroyed will cause us to exit. This is what we 735 * want since another thread is patiently waiting for us to exit 736 * in that case. 737 */ 738 p = curproc; 739 imgp->vmspace_destroyed = 1; 740 741 if (curthread->td_proc->p_nthreads > 1) { 742 error = killalllwps(1); 743 if (error) 744 return (error); 745 } 746 imgp->vmspace_destroyed |= 2; /* we are responsible for P_INEXEC */ 747 p->p_flag |= P_INEXEC; 748 749 /* 750 * Blow away entire process VM, if address space not shared, 751 * otherwise, create a new VM space so that other threads are 752 * not disrupted. If we are execing a resident vmspace we 753 * create a duplicate of it and remap the stack. 754 * 755 * The exitingcnt test is not strictly necessary but has been 756 * included for code sanity (to make the code more deterministic). 757 */ 758 map = &vmspace->vm_map; 759 if (vmcopy) { 760 vmspace_exec(imgp->proc, vmcopy); 761 vmspace = imgp->proc->p_vmspace; 762 pmap_remove_pages(vmspace_pmap(vmspace), stack_addr, USRSTACK); 763 map = &vmspace->vm_map; 764 } else if (vmspace->vm_sysref.refcnt == 1 && 765 vmspace->vm_exitingcnt == 0) { 766 shmexit(vmspace); 767 if (vmspace->vm_upcalls) 768 upc_release(vmspace, ONLY_LWP_IN_PROC(imgp->proc)); 769 pmap_remove_pages(vmspace_pmap(vmspace), 770 0, VM_MAX_USER_ADDRESS); 771 vm_map_remove(map, 0, VM_MAX_USER_ADDRESS); 772 } else { 773 vmspace_exec(imgp->proc, NULL); 774 vmspace = imgp->proc->p_vmspace; 775 map = &vmspace->vm_map; 776 } 777 778 /* Allocate a new stack */ 779 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 780 0, VM_PROT_ALL, VM_PROT_ALL, 0); 781 if (error) 782 return (error); 783 784 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 785 * VM_STACK case, but they are still used to monitor the size of the 786 * process stack so we can check the stack rlimit. 787 */ 788 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 789 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 790 791 return(0); 792 } 793 794 /* 795 * Copy out argument and environment strings from the old process 796 * address space into the temporary string buffer. 797 */ 798 int 799 exec_copyin_args(struct image_args *args, char *fname, 800 enum exec_path_segflg segflg, char **argv, char **envv) 801 { 802 char *argp, *envp; 803 int error = 0; 804 size_t length; 805 806 args->buf = objcache_get(exec_objcache, M_WAITOK); 807 if (args->buf == NULL) 808 return (ENOMEM); 809 args->begin_argv = args->buf; 810 args->endp = args->begin_argv; 811 args->space = ARG_MAX; 812 813 args->fname = args->buf + ARG_MAX; 814 815 /* 816 * Copy the file name. 817 */ 818 if (segflg == PATH_SYSSPACE) { 819 error = copystr(fname, args->fname, PATH_MAX, &length); 820 } else if (segflg == PATH_USERSPACE) { 821 error = copyinstr(fname, args->fname, PATH_MAX, &length); 822 } 823 824 /* 825 * Extract argument strings. argv may not be NULL. The argv 826 * array is terminated by a NULL entry. We special-case the 827 * situation where argv[0] is NULL by passing { filename, NULL } 828 * to the new program to guarentee that the interpreter knows what 829 * file to open in case we exec an interpreted file. Note that 830 * a NULL argv[0] terminates the argv[] array. 831 * 832 * XXX the special-casing of argv[0] is historical and needs to be 833 * revisited. 834 */ 835 if (argv == NULL) 836 error = EFAULT; 837 if (error == 0) { 838 while ((argp = (caddr_t)(intptr_t)fuword(argv++)) != NULL) { 839 if (argp == (caddr_t)-1) { 840 error = EFAULT; 841 break; 842 } 843 error = copyinstr(argp, args->endp, 844 args->space, &length); 845 if (error) { 846 if (error == ENAMETOOLONG) 847 error = E2BIG; 848 break; 849 } 850 args->space -= length; 851 args->endp += length; 852 args->argc++; 853 } 854 if (args->argc == 0 && error == 0) { 855 length = strlen(args->fname) + 1; 856 if (length > args->space) { 857 error = E2BIG; 858 } else { 859 bcopy(args->fname, args->endp, length); 860 args->space -= length; 861 args->endp += length; 862 args->argc++; 863 } 864 } 865 } 866 867 args->begin_envv = args->endp; 868 869 /* 870 * extract environment strings. envv may be NULL. 871 */ 872 if (envv && error == 0) { 873 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 874 if (envp == (caddr_t) -1) { 875 error = EFAULT; 876 break; 877 } 878 error = copyinstr(envp, args->endp, args->space, 879 &length); 880 if (error) { 881 if (error == ENAMETOOLONG) 882 error = E2BIG; 883 break; 884 } 885 args->space -= length; 886 args->endp += length; 887 args->envc++; 888 } 889 } 890 return (error); 891 } 892 893 void 894 exec_free_args(struct image_args *args) 895 { 896 if (args->buf) { 897 objcache_put(exec_objcache, args->buf); 898 args->buf = NULL; 899 } 900 } 901 902 /* 903 * Copy strings out to the new process address space, constructing 904 * new arg and env vector tables. Return a pointer to the base 905 * so that it can be used as the initial stack pointer. 906 */ 907 register_t * 908 exec_copyout_strings(struct image_params *imgp) 909 { 910 int argc, envc, sgap; 911 char **vectp; 912 char *stringp, *destp; 913 register_t *stack_base; 914 struct ps_strings *arginfo; 915 size_t execpath_len; 916 int szsigcode; 917 918 /* 919 * Calculate string base and vector table pointers. 920 * Also deal with signal trampoline code for this exec type. 921 */ 922 if (imgp->execpath != NULL && imgp->auxargs != NULL) 923 execpath_len = strlen(imgp->execpath) + 1; 924 else 925 execpath_len = 0; 926 arginfo = (struct ps_strings *)PS_STRINGS; 927 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 928 if (stackgap_random != 0) 929 sgap = ALIGN(karc4random() & (stackgap_random - 1)); 930 else 931 sgap = 0; 932 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - sgap - 933 roundup(execpath_len, sizeof(char *)) - 934 roundup((ARG_MAX - imgp->args->space), sizeof(char *)); 935 936 /* 937 * install sigcode 938 */ 939 if (szsigcode) 940 copyout(imgp->proc->p_sysent->sv_sigcode, 941 ((caddr_t)arginfo - szsigcode), szsigcode); 942 943 /* 944 * Copy the image path for the rtld 945 */ 946 if (execpath_len != 0) { 947 imgp->execpathp = (uintptr_t)arginfo 948 - szsigcode 949 - execpath_len; 950 copyout(imgp->execpath, (void *)imgp->execpathp, execpath_len); 951 } 952 953 /* 954 * If we have a valid auxargs ptr, prepare some room 955 * on the stack. 956 * 957 * The '+ 2' is for the null pointers at the end of each of the 958 * arg and env vector sets, and 'AT_COUNT*2' is room for the 959 * ELF Auxargs data. 960 */ 961 if (imgp->auxargs) { 962 vectp = (char **)(destp - (imgp->args->argc + 963 imgp->args->envc + 2 + (AT_COUNT * 2) + execpath_len) * 964 sizeof(char*)); 965 } else { 966 vectp = (char **)(destp - (imgp->args->argc + 967 imgp->args->envc + 2) * sizeof(char*)); 968 } 969 970 /* 971 * NOTE: don't bother aligning the stack here for GCC 2.x, it will 972 * be done in crt1.o. Note that GCC 3.x aligns the stack in main. 973 */ 974 975 /* 976 * vectp also becomes our initial stack base 977 */ 978 stack_base = (register_t *)vectp; 979 980 stringp = imgp->args->begin_argv; 981 argc = imgp->args->argc; 982 envc = imgp->args->envc; 983 984 /* 985 * Copy out strings - arguments and environment. 986 */ 987 copyout(stringp, destp, ARG_MAX - imgp->args->space); 988 989 /* 990 * Fill in "ps_strings" struct for ps, w, etc. 991 */ 992 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 993 suword(&arginfo->ps_nargvstr, argc); 994 995 /* 996 * Fill in argument portion of vector table. 997 */ 998 for (; argc > 0; --argc) { 999 suword(vectp++, (long)(intptr_t)destp); 1000 while (*stringp++ != 0) 1001 destp++; 1002 destp++; 1003 } 1004 1005 /* a null vector table pointer separates the argp's from the envp's */ 1006 suword(vectp++, 0); 1007 1008 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1009 suword(&arginfo->ps_nenvstr, envc); 1010 1011 /* 1012 * Fill in environment portion of vector table. 1013 */ 1014 for (; envc > 0; --envc) { 1015 suword(vectp++, (long)(intptr_t)destp); 1016 while (*stringp++ != 0) 1017 destp++; 1018 destp++; 1019 } 1020 1021 /* end of vector table is a null pointer */ 1022 suword(vectp, 0); 1023 1024 return (stack_base); 1025 } 1026 1027 /* 1028 * Check permissions of file to execute. 1029 * Return 0 for success or error code on failure. 1030 */ 1031 int 1032 exec_check_permissions(struct image_params *imgp, struct mount *topmnt) 1033 { 1034 struct proc *p = imgp->proc; 1035 struct vnode *vp = imgp->vp; 1036 struct vattr *attr = imgp->attr; 1037 int error; 1038 1039 /* Get file attributes */ 1040 error = VOP_GETATTR(vp, attr); 1041 if (error) 1042 return (error); 1043 1044 /* 1045 * 1) Check if file execution is disabled for the filesystem that this 1046 * file resides on. 1047 * 2) Insure that at least one execute bit is on - otherwise root 1048 * will always succeed, and we don't want to happen unless the 1049 * file really is executable. 1050 * 3) Insure that the file is a regular file. 1051 */ 1052 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1053 ((topmnt != NULL) && (topmnt->mnt_flag & MNT_NOEXEC)) || 1054 ((attr->va_mode & 0111) == 0) || 1055 (attr->va_type != VREG)) { 1056 return (EACCES); 1057 } 1058 1059 /* 1060 * Zero length files can't be exec'd 1061 */ 1062 if (attr->va_size == 0) 1063 return (ENOEXEC); 1064 1065 /* 1066 * Check for execute permission to file based on current credentials. 1067 */ 1068 error = VOP_EACCESS(vp, VEXEC, p->p_ucred); 1069 if (error) 1070 return (error); 1071 1072 /* 1073 * Check number of open-for-writes on the file and deny execution 1074 * if there are any. 1075 */ 1076 if (vp->v_writecount) 1077 return (ETXTBSY); 1078 1079 /* 1080 * Call filesystem specific open routine, which allows us to read, 1081 * write, and mmap the file. Without the VOP_OPEN we can only 1082 * stat the file. 1083 */ 1084 error = VOP_OPEN(vp, FREAD, p->p_ucred, NULL); 1085 if (error) 1086 return (error); 1087 1088 return (0); 1089 } 1090 1091 /* 1092 * Exec handler registration 1093 */ 1094 int 1095 exec_register(const struct execsw *execsw_arg) 1096 { 1097 const struct execsw **es, **xs, **newexecsw; 1098 int count = 2; /* New slot and trailing NULL */ 1099 1100 if (execsw) 1101 for (es = execsw; *es; es++) 1102 count++; 1103 newexecsw = kmalloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1104 xs = newexecsw; 1105 if (execsw) 1106 for (es = execsw; *es; es++) 1107 *xs++ = *es; 1108 *xs++ = execsw_arg; 1109 *xs = NULL; 1110 if (execsw) 1111 kfree(execsw, M_TEMP); 1112 execsw = newexecsw; 1113 return 0; 1114 } 1115 1116 int 1117 exec_unregister(const struct execsw *execsw_arg) 1118 { 1119 const struct execsw **es, **xs, **newexecsw; 1120 int count = 1; 1121 1122 if (execsw == NULL) 1123 panic("unregister with no handlers left?"); 1124 1125 for (es = execsw; *es; es++) { 1126 if (*es == execsw_arg) 1127 break; 1128 } 1129 if (*es == NULL) 1130 return ENOENT; 1131 for (es = execsw; *es; es++) 1132 if (*es != execsw_arg) 1133 count++; 1134 newexecsw = kmalloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1135 xs = newexecsw; 1136 for (es = execsw; *es; es++) 1137 if (*es != execsw_arg) 1138 *xs++ = *es; 1139 *xs = NULL; 1140 if (execsw) 1141 kfree(execsw, M_TEMP); 1142 execsw = newexecsw; 1143 return 0; 1144 } 1145