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