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 size_t limsize; 116 117 /* 118 * Maximum number of concurrent execs. This can be limiting on 119 * systems with a lot of cpu cores but it also eats a significant 120 * amount of memory. 121 */ 122 cluster_limit = 16; 123 limsize = kmem_lim_size(); 124 if (limsize > 7 * 1024) 125 cluster_limit *= 2; 126 if (limsize > 15 * 1024) 127 cluster_limit *= 2; 128 129 exec_objcache = objcache_create_mbacked( 130 M_EXECARGS, PATH_MAX + ARG_MAX, 131 &cluster_limit, 8, 132 NULL, NULL, NULL); 133 } 134 SYSINIT(exec_objcache, SI_BOOT2_MACHDEP, SI_ORDER_ANY, exec_objcache_init, 0); 135 136 /* 137 * stackgap_random specifies if the stackgap should have a random size added 138 * to it. It must be a power of 2. If non-zero, the stack gap will be 139 * calculated as: ALIGN(karc4random() & (stackgap_random - 1)). 140 */ 141 static int stackgap_random = 1024; 142 static int 143 sysctl_kern_stackgap(SYSCTL_HANDLER_ARGS) 144 { 145 int error, new_val; 146 new_val = stackgap_random; 147 error = sysctl_handle_int(oidp, &new_val, 0, req); 148 if (error != 0 || req->newptr == NULL) 149 return (error); 150 if ((new_val < 0) || (new_val > 16 * PAGE_SIZE) || ! powerof2(new_val)) 151 return (EINVAL); 152 stackgap_random = new_val; 153 154 return(0); 155 } 156 157 SYSCTL_PROC(_kern, OID_AUTO, stackgap_random, CTLFLAG_RW|CTLTYPE_UINT, 158 0, 0, sysctl_kern_stackgap, "IU", "Max random stack gap (power of 2)"); 159 160 void 161 print_execve_args(struct image_args *args) 162 { 163 char *cp; 164 int ndx; 165 166 cp = args->begin_argv; 167 for (ndx = 0; ndx < args->argc; ndx++) { 168 kprintf("\targv[%d]: %s\n", ndx, cp); 169 while (*cp++ != '\0'); 170 } 171 for (ndx = 0; ndx < args->envc; ndx++) { 172 kprintf("\tenvv[%d]: %s\n", ndx, cp); 173 while (*cp++ != '\0'); 174 } 175 } 176 177 /* 178 * Each of the items is a pointer to a `const struct execsw', hence the 179 * double pointer here. 180 */ 181 static const struct execsw **execsw; 182 183 /* 184 * Replace current vmspace with a new binary. 185 * Returns 0 on success, > 0 on recoverable error (use as errno). 186 * Returns -1 on lethal error which demands killing of the current 187 * process! 188 */ 189 int 190 kern_execve(struct nlookupdata *nd, struct image_args *args) 191 { 192 struct thread *td = curthread; 193 struct lwp *lp = td->td_lwp; 194 struct proc *p = td->td_proc; 195 register_t *stack_base; 196 struct pargs *pa; 197 struct sigacts *ops; 198 struct sigacts *nps; 199 int error, len, i; 200 struct image_params image_params, *imgp; 201 struct vattr attr; 202 int (*img_first) (struct image_params *); 203 204 if (debug_execve_args) { 205 kprintf("%s()\n", __func__); 206 print_execve_args(args); 207 } 208 209 KKASSERT(p); 210 lwkt_gettoken(&p->p_token); 211 imgp = &image_params; 212 213 /* 214 * NOTE: P_INEXEC is handled by exec_new_vmspace() now. We make 215 * no modifications to the process at all until we get there. 216 * 217 * Note that multiple threads may be trying to exec at the same 218 * time. exec_new_vmspace() handles that too. 219 */ 220 221 /* 222 * Initialize part of the common data 223 */ 224 imgp->proc = p; 225 imgp->args = args; 226 imgp->attr = &attr; 227 imgp->entry_addr = 0; 228 imgp->resident = 0; 229 imgp->vmspace_destroyed = 0; 230 imgp->interpreted = 0; 231 imgp->interpreter_name[0] = 0; 232 imgp->auxargs = NULL; 233 imgp->vp = NULL; 234 imgp->firstpage = NULL; 235 imgp->ps_strings = 0; 236 imgp->execpath = imgp->freepath = NULL; 237 imgp->execpathp = 0; 238 imgp->image_header = NULL; 239 240 interpret: 241 242 /* 243 * Translate the file name to a vnode. Unlock the cache entry to 244 * improve parallelism for programs exec'd in parallel. 245 */ 246 if ((error = nlookup(nd)) != 0) 247 goto exec_fail; 248 error = cache_vget(&nd->nl_nch, nd->nl_cred, LK_EXCLUSIVE, &imgp->vp); 249 KKASSERT(nd->nl_flags & NLC_NCPISLOCKED); 250 nd->nl_flags &= ~NLC_NCPISLOCKED; 251 cache_unlock(&nd->nl_nch); 252 if (error) 253 goto exec_fail; 254 255 /* 256 * Check file permissions (also 'opens' file). 257 * Include also the top level mount in the check. 258 */ 259 error = exec_check_permissions(imgp, nd->nl_nch.mount); 260 if (error) { 261 vn_unlock(imgp->vp); 262 goto exec_fail_dealloc; 263 } 264 265 error = exec_map_first_page(imgp); 266 vn_unlock(imgp->vp); 267 if (error) 268 goto exec_fail_dealloc; 269 270 imgp->proc->p_osrel = 0; 271 272 if (debug_execve_args && imgp->interpreted) { 273 kprintf(" target is interpreted -- recursive pass\n"); 274 kprintf(" interpreter: %s\n", imgp->interpreter_name); 275 print_execve_args(args); 276 } 277 278 /* 279 * If the current process has a special image activator it 280 * wants to try first, call it. For example, emulating shell 281 * scripts differently. 282 */ 283 error = -1; 284 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 285 error = img_first(imgp); 286 287 /* 288 * If the vnode has a registered vmspace, exec the vmspace 289 */ 290 if (error == -1 && imgp->vp->v_resident) { 291 error = exec_resident_imgact(imgp); 292 } 293 294 /* 295 * Loop through the list of image activators, calling each one. 296 * An activator returns -1 if there is no match, 0 on success, 297 * and an error otherwise. 298 */ 299 for (i = 0; error == -1 && execsw[i]; ++i) { 300 if (execsw[i]->ex_imgact == NULL || 301 execsw[i]->ex_imgact == img_first) { 302 continue; 303 } 304 error = (*execsw[i]->ex_imgact)(imgp); 305 } 306 307 if (error) { 308 if (error == -1) 309 error = ENOEXEC; 310 goto exec_fail_dealloc; 311 } 312 313 /* 314 * Special interpreter operation, cleanup and loop up to try to 315 * activate the interpreter. 316 */ 317 if (imgp->interpreted) { 318 exec_unmap_first_page(imgp); 319 nlookup_done(nd); 320 vrele(imgp->vp); 321 imgp->vp = NULL; 322 error = nlookup_init(nd, imgp->interpreter_name, UIO_SYSSPACE, 323 NLC_FOLLOW); 324 if (error) 325 goto exec_fail; 326 goto interpret; 327 } 328 329 /* 330 * Do the best to calculate the full path to the image file 331 */ 332 if (imgp->auxargs != NULL && 333 ((args->fname != NULL && args->fname[0] == '/') || 334 vn_fullpath(imgp->proc, 335 imgp->vp, 336 &imgp->execpath, 337 &imgp->freepath, 338 0) != 0)) 339 imgp->execpath = args->fname; 340 341 /* 342 * Copy out strings (args and env) and initialize stack base 343 */ 344 stack_base = exec_copyout_strings(imgp); 345 p->p_vmspace->vm_minsaddr = (char *)stack_base; 346 347 /* 348 * If custom stack fixup routine present for this process 349 * let it do the stack setup. If we are running a resident 350 * image there is no auxinfo or other image activator context 351 * so don't try to add fixups to the stack. 352 * 353 * Else stuff argument count as first item on stack 354 */ 355 if (p->p_sysent->sv_fixup && imgp->resident == 0) 356 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 357 else 358 suword(--stack_base, imgp->args->argc); 359 360 /* 361 * For security and other reasons, the file descriptor table cannot 362 * be shared after an exec. 363 */ 364 if (p->p_fd->fd_refcnt > 1) { 365 struct filedesc *tmp; 366 367 error = fdcopy(p, &tmp); 368 if (error != 0) 369 goto exec_fail; 370 fdfree(p, tmp); 371 } 372 373 /* 374 * For security and other reasons, signal handlers cannot 375 * be shared after an exec. The new proces gets a copy of the old 376 * handlers. In execsigs(), the new process will have its signals 377 * reset. 378 */ 379 ops = p->p_sigacts; 380 if (ops->ps_refcnt > 1) { 381 nps = kmalloc(sizeof(*nps), M_SUBPROC, M_WAITOK); 382 bcopy(ops, nps, sizeof(*nps)); 383 refcount_init(&nps->ps_refcnt, 1); 384 p->p_sigacts = nps; 385 if (refcount_release(&ops->ps_refcnt)) { 386 kfree(ops, M_SUBPROC); 387 ops = NULL; 388 } 389 } 390 391 /* 392 * For security and other reasons virtual kernels cannot be 393 * inherited by an exec. This also allows a virtual kernel 394 * to fork/exec unrelated applications. 395 */ 396 if (p->p_vkernel) 397 vkernel_exit(p); 398 399 /* Stop profiling */ 400 stopprofclock(p); 401 402 /* close files on exec */ 403 fdcloseexec(p); 404 405 /* reset caught signals */ 406 execsigs(p); 407 408 /* name this process - nameiexec(p, ndp) */ 409 len = min(nd->nl_nch.ncp->nc_nlen, MAXCOMLEN); 410 bcopy(nd->nl_nch.ncp->nc_name, p->p_comm, len); 411 p->p_comm[len] = 0; 412 bcopy(p->p_comm, lp->lwp_thread->td_comm, MAXCOMLEN+1); 413 414 /* 415 * mark as execed, wakeup the process that vforked (if any) and tell 416 * it that it now has its own resources back 417 */ 418 p->p_flag |= P_EXEC; 419 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 420 p->p_flag &= ~P_PPWAIT; 421 wakeup((caddr_t)p->p_pptr); 422 } 423 424 /* 425 * Implement image setuid/setgid. 426 * 427 * Don't honor setuid/setgid if the filesystem prohibits it or if 428 * the process is being traced. 429 */ 430 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 431 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 432 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 433 (p->p_flag & P_TRACED) == 0) { 434 /* 435 * Turn off syscall tracing for set-id programs, except for 436 * root. Record any set-id flags first to make sure that 437 * we do not regain any tracing during a possible block. 438 */ 439 setsugid(); 440 if (p->p_tracenode && ktrace_suid == 0 && 441 priv_check(td, PRIV_ROOT) != 0) { 442 ktrdestroy(&p->p_tracenode); 443 p->p_traceflag = 0; 444 } 445 /* Close any file descriptors 0..2 that reference procfs */ 446 setugidsafety(p); 447 /* Make sure file descriptors 0..2 are in use. */ 448 error = fdcheckstd(lp); 449 if (error != 0) 450 goto exec_fail_dealloc; 451 /* 452 * Set the new credentials. 453 */ 454 cratom(&p->p_ucred); 455 if (attr.va_mode & VSUID) 456 change_euid(attr.va_uid); 457 if (attr.va_mode & VSGID) 458 p->p_ucred->cr_gid = attr.va_gid; 459 460 /* 461 * Clear local varsym variables 462 */ 463 varsymset_clean(&p->p_varsymset); 464 } else { 465 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && 466 p->p_ucred->cr_gid == p->p_ucred->cr_rgid) 467 p->p_flag &= ~P_SUGID; 468 } 469 470 /* 471 * Implement correct POSIX saved-id behavior. 472 */ 473 if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || 474 p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { 475 cratom(&p->p_ucred); 476 p->p_ucred->cr_svuid = p->p_ucred->cr_uid; 477 p->p_ucred->cr_svgid = p->p_ucred->cr_gid; 478 } 479 480 /* 481 * Store the vp for use in procfs 482 */ 483 if (p->p_textvp) /* release old reference */ 484 vrele(p->p_textvp); 485 p->p_textvp = imgp->vp; 486 vref(p->p_textvp); 487 488 /* Release old namecache handle to text file */ 489 if (p->p_textnch.ncp) 490 cache_drop(&p->p_textnch); 491 492 if (nd->nl_nch.mount) 493 cache_copy(&nd->nl_nch, &p->p_textnch); 494 495 /* 496 * Notify others that we exec'd, and clear the P_INEXEC flag 497 * as we're now a bona fide freshly-execed process. 498 */ 499 KNOTE(&p->p_klist, NOTE_EXEC); 500 p->p_flag &= ~P_INEXEC; 501 502 /* 503 * If tracing the process, trap to debugger so breakpoints 504 * can be set before the program executes. 505 */ 506 STOPEVENT(p, S_EXEC, 0); 507 508 if (p->p_flag & P_TRACED) 509 ksignal(p, SIGTRAP); 510 511 /* clear "fork but no exec" flag, as we _are_ execing */ 512 p->p_acflag &= ~AFORK; 513 514 /* Set values passed into the program in registers. */ 515 exec_setregs(imgp->entry_addr, (u_long)(uintptr_t)stack_base, 516 imgp->ps_strings); 517 518 /* Set the access time on the vnode */ 519 vn_mark_atime(imgp->vp, td); 520 521 /* 522 * Free any previous argument cache 523 */ 524 pa = p->p_args; 525 p->p_args = NULL; 526 if (pa && refcount_release(&pa->ar_ref)) { 527 kfree(pa, M_PARGS); 528 pa = NULL; 529 } 530 531 /* 532 * Cache arguments if they fit inside our allowance 533 */ 534 i = imgp->args->begin_envv - imgp->args->begin_argv; 535 if (sizeof(struct pargs) + i <= ps_arg_cache_limit) { 536 pa = kmalloc(sizeof(struct pargs) + i, M_PARGS, M_WAITOK); 537 refcount_init(&pa->ar_ref, 1); 538 pa->ar_length = i; 539 bcopy(imgp->args->begin_argv, pa->ar_args, i); 540 KKASSERT(p->p_args == NULL); 541 p->p_args = pa; 542 } 543 544 exec_fail_dealloc: 545 546 /* 547 * free various allocated resources 548 */ 549 if (imgp->firstpage) 550 exec_unmap_first_page(imgp); 551 552 if (imgp->vp) { 553 vrele(imgp->vp); 554 imgp->vp = NULL; 555 } 556 557 if (imgp->freepath) 558 kfree(imgp->freepath, M_TEMP); 559 560 if (error == 0) { 561 ++mycpu->gd_cnt.v_exec; 562 lwkt_reltoken(&p->p_token); 563 return (0); 564 } 565 566 exec_fail: 567 /* 568 * we're done here, clear P_INEXEC if we were the ones that 569 * set it. Otherwise if vmspace_destroyed is still set we 570 * raced another thread and that thread is responsible for 571 * clearing it. 572 */ 573 if (imgp->vmspace_destroyed & 2) 574 p->p_flag &= ~P_INEXEC; 575 lwkt_reltoken(&p->p_token); 576 if (imgp->vmspace_destroyed) { 577 /* 578 * Sorry, no more process anymore. exit gracefully. 579 * However we can't die right here, because our 580 * caller might have to clean up, so indicate a 581 * lethal error by returning -1. 582 */ 583 return(-1); 584 } else { 585 return(error); 586 } 587 } 588 589 /* 590 * execve() system call. 591 */ 592 int 593 sys_execve(struct execve_args *uap) 594 { 595 struct nlookupdata nd; 596 struct image_args args; 597 int error; 598 599 bzero(&args, sizeof(args)); 600 601 error = nlookup_init(&nd, uap->fname, UIO_USERSPACE, NLC_FOLLOW); 602 if (error == 0) { 603 error = exec_copyin_args(&args, uap->fname, PATH_USERSPACE, 604 uap->argv, uap->envv); 605 } 606 if (error == 0) 607 error = kern_execve(&nd, &args); 608 nlookup_done(&nd); 609 exec_free_args(&args); 610 611 if (error < 0) { 612 /* We hit a lethal error condition. Let's die now. */ 613 exit1(W_EXITCODE(0, SIGABRT)); 614 /* NOTREACHED */ 615 } 616 617 /* 618 * The syscall result is returned in registers to the new program. 619 * Linux will register %edx as an atexit function and we must be 620 * sure to set it to 0. XXX 621 */ 622 if (error == 0) 623 uap->sysmsg_result64 = 0; 624 625 return (error); 626 } 627 628 int 629 exec_map_page(struct image_params *imgp, vm_pindex_t pageno, 630 struct lwbuf **plwb, const char **pdata) 631 { 632 int rv; 633 vm_page_t ma; 634 vm_page_t m; 635 vm_object_t object; 636 637 /* 638 * The file has to be mappable. 639 */ 640 if ((object = imgp->vp->v_object) == NULL) 641 return (EIO); 642 643 if (pageno >= object->size) 644 return (EIO); 645 646 vm_object_hold(object); 647 m = vm_page_grab(object, pageno, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 648 while ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 649 ma = m; 650 651 /* 652 * get_pages unbusies all the requested pages except the 653 * primary page (at index 0 in this case). The primary 654 * page may have been wired during the pagein (e.g. by 655 * the buffer cache) so vnode_pager_freepage() must be 656 * used to properly release it. 657 */ 658 rv = vm_pager_get_page(object, &ma, 1); 659 m = vm_page_lookup(object, pageno); 660 661 if (rv != VM_PAGER_OK || m == NULL || m->valid == 0) { 662 if (m) { 663 vm_page_protect(m, VM_PROT_NONE); 664 vnode_pager_freepage(m); 665 } 666 return EIO; 667 } 668 } 669 vm_page_hold(m); 670 vm_page_wakeup(m); /* unbusy the page */ 671 vm_object_drop(object); 672 673 *plwb = lwbuf_alloc(m, *plwb); 674 *pdata = (void *)lwbuf_kva(*plwb); 675 676 return (0); 677 } 678 679 /* 680 * Map the first page of an executable image. 681 * 682 * NOTE: If the mapping fails we have to NULL-out firstpage which may 683 * still be pointing to our supplied lwp structure. 684 */ 685 int 686 exec_map_first_page(struct image_params *imgp) 687 { 688 int err; 689 690 if (imgp->firstpage) 691 exec_unmap_first_page(imgp); 692 693 imgp->firstpage = &imgp->firstpage_cache; 694 err = exec_map_page(imgp, 0, &imgp->firstpage, &imgp->image_header); 695 696 if (err) { 697 imgp->firstpage = NULL; 698 return err; 699 } 700 701 return 0; 702 } 703 704 void 705 exec_unmap_page(struct lwbuf *lwb) 706 { 707 vm_page_t m; 708 709 crit_enter(); 710 if (lwb != NULL) { 711 m = lwbuf_page(lwb); 712 lwbuf_free(lwb); 713 vm_page_unhold(m); 714 } 715 crit_exit(); 716 } 717 718 void 719 exec_unmap_first_page(struct image_params *imgp) 720 { 721 exec_unmap_page(imgp->firstpage); 722 imgp->firstpage = NULL; 723 imgp->image_header = NULL; 724 } 725 726 /* 727 * Destroy old address space, and allocate a new stack 728 * The new stack is only SGROWSIZ large because it is grown 729 * automatically in trap.c. 730 * 731 * This is the point of no return. 732 */ 733 int 734 exec_new_vmspace(struct image_params *imgp, struct vmspace *vmcopy) 735 { 736 struct vmspace *vmspace = imgp->proc->p_vmspace; 737 vm_offset_t stack_addr = USRSTACK - maxssiz; 738 struct proc *p; 739 vm_map_t map; 740 int error; 741 742 /* 743 * Indicate that we cannot gracefully error out any more, kill 744 * any other threads present, and set P_INEXEC to indicate that 745 * we are now messing with the process structure proper. 746 * 747 * If killalllwps() races return an error which coupled with 748 * vmspace_destroyed will cause us to exit. This is what we 749 * want since another thread is patiently waiting for us to exit 750 * in that case. 751 */ 752 p = curproc; 753 imgp->vmspace_destroyed = 1; 754 755 if (curthread->td_proc->p_nthreads > 1) { 756 error = killalllwps(1); 757 if (error) 758 return (error); 759 } 760 imgp->vmspace_destroyed |= 2; /* we are responsible for P_INEXEC */ 761 p->p_flag |= P_INEXEC; 762 763 /* 764 * Blow away entire process VM, if address space not shared, 765 * otherwise, create a new VM space so that other threads are 766 * not disrupted. If we are execing a resident vmspace we 767 * create a duplicate of it and remap the stack. 768 * 769 * The exitingcnt test is not strictly necessary but has been 770 * included for code sanity (to make the code more deterministic). 771 */ 772 map = &vmspace->vm_map; 773 if (vmcopy) { 774 vmspace_exec(imgp->proc, vmcopy); 775 vmspace = imgp->proc->p_vmspace; 776 pmap_remove_pages(vmspace_pmap(vmspace), stack_addr, USRSTACK); 777 map = &vmspace->vm_map; 778 } else if (vmspace->vm_sysref.refcnt == 1 && 779 vmspace->vm_exitingcnt == 0) { 780 shmexit(vmspace); 781 if (vmspace->vm_upcalls) 782 upc_release(vmspace, ONLY_LWP_IN_PROC(imgp->proc)); 783 pmap_remove_pages(vmspace_pmap(vmspace), 784 0, VM_MAX_USER_ADDRESS); 785 vm_map_remove(map, 0, VM_MAX_USER_ADDRESS); 786 } else { 787 vmspace_exec(imgp->proc, NULL); 788 vmspace = imgp->proc->p_vmspace; 789 map = &vmspace->vm_map; 790 } 791 792 /* Allocate a new stack */ 793 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 794 0, VM_PROT_ALL, VM_PROT_ALL, 0); 795 if (error) 796 return (error); 797 798 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 799 * VM_STACK case, but they are still used to monitor the size of the 800 * process stack so we can check the stack rlimit. 801 */ 802 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 803 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 804 805 return(0); 806 } 807 808 /* 809 * Copy out argument and environment strings from the old process 810 * address space into the temporary string buffer. 811 */ 812 int 813 exec_copyin_args(struct image_args *args, char *fname, 814 enum exec_path_segflg segflg, char **argv, char **envv) 815 { 816 char *argp, *envp; 817 int error = 0; 818 size_t length; 819 820 args->buf = objcache_get(exec_objcache, M_WAITOK); 821 if (args->buf == NULL) 822 return (ENOMEM); 823 args->begin_argv = args->buf; 824 args->endp = args->begin_argv; 825 args->space = ARG_MAX; 826 827 args->fname = args->buf + ARG_MAX; 828 829 /* 830 * Copy the file name. 831 */ 832 if (segflg == PATH_SYSSPACE) { 833 error = copystr(fname, args->fname, PATH_MAX, &length); 834 } else if (segflg == PATH_USERSPACE) { 835 error = copyinstr(fname, args->fname, PATH_MAX, &length); 836 } 837 838 /* 839 * Extract argument strings. argv may not be NULL. The argv 840 * array is terminated by a NULL entry. We special-case the 841 * situation where argv[0] is NULL by passing { filename, NULL } 842 * to the new program to guarentee that the interpreter knows what 843 * file to open in case we exec an interpreted file. Note that 844 * a NULL argv[0] terminates the argv[] array. 845 * 846 * XXX the special-casing of argv[0] is historical and needs to be 847 * revisited. 848 */ 849 if (argv == NULL) 850 error = EFAULT; 851 if (error == 0) { 852 while ((argp = (caddr_t)(intptr_t)fuword(argv++)) != NULL) { 853 if (argp == (caddr_t)-1) { 854 error = EFAULT; 855 break; 856 } 857 error = copyinstr(argp, args->endp, 858 args->space, &length); 859 if (error) { 860 if (error == ENAMETOOLONG) 861 error = E2BIG; 862 break; 863 } 864 args->space -= length; 865 args->endp += length; 866 args->argc++; 867 } 868 if (args->argc == 0 && error == 0) { 869 length = strlen(args->fname) + 1; 870 if (length > args->space) { 871 error = E2BIG; 872 } else { 873 bcopy(args->fname, args->endp, length); 874 args->space -= length; 875 args->endp += length; 876 args->argc++; 877 } 878 } 879 } 880 881 args->begin_envv = args->endp; 882 883 /* 884 * extract environment strings. envv may be NULL. 885 */ 886 if (envv && error == 0) { 887 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 888 if (envp == (caddr_t) -1) { 889 error = EFAULT; 890 break; 891 } 892 error = copyinstr(envp, args->endp, args->space, 893 &length); 894 if (error) { 895 if (error == ENAMETOOLONG) 896 error = E2BIG; 897 break; 898 } 899 args->space -= length; 900 args->endp += length; 901 args->envc++; 902 } 903 } 904 return (error); 905 } 906 907 void 908 exec_free_args(struct image_args *args) 909 { 910 if (args->buf) { 911 objcache_put(exec_objcache, args->buf); 912 args->buf = NULL; 913 } 914 } 915 916 /* 917 * Copy strings out to the new process address space, constructing 918 * new arg and env vector tables. Return a pointer to the base 919 * so that it can be used as the initial stack pointer. 920 */ 921 register_t * 922 exec_copyout_strings(struct image_params *imgp) 923 { 924 int argc, envc, sgap; 925 char **vectp; 926 char *stringp, *destp; 927 register_t *stack_base; 928 struct ps_strings *arginfo; 929 size_t execpath_len; 930 int szsigcode; 931 932 /* 933 * Calculate string base and vector table pointers. 934 * Also deal with signal trampoline code for this exec type. 935 */ 936 if (imgp->execpath != NULL && imgp->auxargs != NULL) 937 execpath_len = strlen(imgp->execpath) + 1; 938 else 939 execpath_len = 0; 940 arginfo = (struct ps_strings *)PS_STRINGS; 941 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 942 if (stackgap_random != 0) 943 sgap = ALIGN(karc4random() & (stackgap_random - 1)); 944 else 945 sgap = 0; 946 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - sgap - 947 roundup(execpath_len, sizeof(char *)) - 948 roundup((ARG_MAX - imgp->args->space), sizeof(char *)); 949 950 /* 951 * install sigcode 952 */ 953 if (szsigcode) 954 copyout(imgp->proc->p_sysent->sv_sigcode, 955 ((caddr_t)arginfo - szsigcode), szsigcode); 956 957 /* 958 * Copy the image path for the rtld 959 */ 960 if (execpath_len != 0) { 961 imgp->execpathp = (uintptr_t)arginfo 962 - szsigcode 963 - execpath_len; 964 copyout(imgp->execpath, (void *)imgp->execpathp, execpath_len); 965 } 966 967 /* 968 * If we have a valid auxargs ptr, prepare some room 969 * on the stack. 970 * 971 * The '+ 2' is for the null pointers at the end of each of the 972 * arg and env vector sets, and 'AT_COUNT*2' is room for the 973 * ELF Auxargs data. 974 */ 975 if (imgp->auxargs) { 976 vectp = (char **)(destp - (imgp->args->argc + 977 imgp->args->envc + 2 + (AT_COUNT * 2) + execpath_len) * 978 sizeof(char*)); 979 } else { 980 vectp = (char **)(destp - (imgp->args->argc + 981 imgp->args->envc + 2) * sizeof(char*)); 982 } 983 984 /* 985 * NOTE: don't bother aligning the stack here for GCC 2.x, it will 986 * be done in crt1.o. Note that GCC 3.x aligns the stack in main. 987 */ 988 989 /* 990 * vectp also becomes our initial stack base 991 */ 992 stack_base = (register_t *)vectp; 993 994 stringp = imgp->args->begin_argv; 995 argc = imgp->args->argc; 996 envc = imgp->args->envc; 997 998 /* 999 * Copy out strings - arguments and environment. 1000 */ 1001 copyout(stringp, destp, ARG_MAX - imgp->args->space); 1002 1003 /* 1004 * Fill in "ps_strings" struct for ps, w, etc. 1005 */ 1006 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1007 suword(&arginfo->ps_nargvstr, argc); 1008 1009 /* 1010 * Fill in argument portion of vector table. 1011 */ 1012 for (; argc > 0; --argc) { 1013 suword(vectp++, (long)(intptr_t)destp); 1014 while (*stringp++ != 0) 1015 destp++; 1016 destp++; 1017 } 1018 1019 /* a null vector table pointer separates the argp's from the envp's */ 1020 suword(vectp++, 0); 1021 1022 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1023 suword(&arginfo->ps_nenvstr, envc); 1024 1025 /* 1026 * Fill in environment portion of vector table. 1027 */ 1028 for (; envc > 0; --envc) { 1029 suword(vectp++, (long)(intptr_t)destp); 1030 while (*stringp++ != 0) 1031 destp++; 1032 destp++; 1033 } 1034 1035 /* end of vector table is a null pointer */ 1036 suword(vectp, 0); 1037 1038 return (stack_base); 1039 } 1040 1041 /* 1042 * Check permissions of file to execute. 1043 * Return 0 for success or error code on failure. 1044 */ 1045 int 1046 exec_check_permissions(struct image_params *imgp, struct mount *topmnt) 1047 { 1048 struct proc *p = imgp->proc; 1049 struct vnode *vp = imgp->vp; 1050 struct vattr *attr = imgp->attr; 1051 int error; 1052 1053 /* Get file attributes */ 1054 error = VOP_GETATTR(vp, attr); 1055 if (error) 1056 return (error); 1057 1058 /* 1059 * 1) Check if file execution is disabled for the filesystem that this 1060 * file resides on. 1061 * 2) Insure that at least one execute bit is on - otherwise root 1062 * will always succeed, and we don't want to happen unless the 1063 * file really is executable. 1064 * 3) Insure that the file is a regular file. 1065 */ 1066 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1067 ((topmnt != NULL) && (topmnt->mnt_flag & MNT_NOEXEC)) || 1068 ((attr->va_mode & 0111) == 0) || 1069 (attr->va_type != VREG)) { 1070 return (EACCES); 1071 } 1072 1073 /* 1074 * Zero length files can't be exec'd 1075 */ 1076 if (attr->va_size == 0) 1077 return (ENOEXEC); 1078 1079 /* 1080 * Check for execute permission to file based on current credentials. 1081 */ 1082 error = VOP_EACCESS(vp, VEXEC, p->p_ucred); 1083 if (error) 1084 return (error); 1085 1086 /* 1087 * Check number of open-for-writes on the file and deny execution 1088 * if there are any. 1089 */ 1090 if (vp->v_writecount) 1091 return (ETXTBSY); 1092 1093 /* 1094 * Call filesystem specific open routine, which allows us to read, 1095 * write, and mmap the file. Without the VOP_OPEN we can only 1096 * stat the file. 1097 */ 1098 error = VOP_OPEN(vp, FREAD, p->p_ucred, NULL); 1099 if (error) 1100 return (error); 1101 1102 return (0); 1103 } 1104 1105 /* 1106 * Exec handler registration 1107 */ 1108 int 1109 exec_register(const struct execsw *execsw_arg) 1110 { 1111 const struct execsw **es, **xs, **newexecsw; 1112 int count = 2; /* New slot and trailing NULL */ 1113 1114 if (execsw) 1115 for (es = execsw; *es; es++) 1116 count++; 1117 newexecsw = kmalloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1118 xs = newexecsw; 1119 if (execsw) 1120 for (es = execsw; *es; es++) 1121 *xs++ = *es; 1122 *xs++ = execsw_arg; 1123 *xs = NULL; 1124 if (execsw) 1125 kfree(execsw, M_TEMP); 1126 execsw = newexecsw; 1127 return 0; 1128 } 1129 1130 int 1131 exec_unregister(const struct execsw *execsw_arg) 1132 { 1133 const struct execsw **es, **xs, **newexecsw; 1134 int count = 1; 1135 1136 if (execsw == NULL) 1137 panic("unregister with no handlers left?"); 1138 1139 for (es = execsw; *es; es++) { 1140 if (*es == execsw_arg) 1141 break; 1142 } 1143 if (*es == NULL) 1144 return ENOENT; 1145 for (es = execsw; *es; es++) 1146 if (*es != execsw_arg) 1147 count++; 1148 newexecsw = kmalloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1149 xs = newexecsw; 1150 for (es = execsw; *es; es++) 1151 if (*es != execsw_arg) 1152 *xs++ = *es; 1153 *xs = NULL; 1154 if (execsw) 1155 kfree(execsw, M_TEMP); 1156 execsw = newexecsw; 1157 return 0; 1158 } 1159