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 struct vnode *ovp; 196 register_t *stack_base; 197 struct pargs *pa; 198 struct sigacts *ops; 199 struct sigacts *nps; 200 int error, len, i; 201 struct image_params image_params, *imgp; 202 struct vattr attr; 203 int (*img_first) (struct image_params *); 204 205 if (debug_execve_args) { 206 kprintf("%s()\n", __func__); 207 print_execve_args(args); 208 } 209 210 KKASSERT(p); 211 lwkt_gettoken(&p->p_token); 212 imgp = &image_params; 213 214 /* 215 * NOTE: P_INEXEC is handled by exec_new_vmspace() now. We make 216 * no modifications to the process at all until we get there. 217 * 218 * Note that multiple threads may be trying to exec at the same 219 * time. exec_new_vmspace() handles that too. 220 */ 221 222 /* 223 * Initialize part of the common data 224 */ 225 imgp->proc = p; 226 imgp->args = args; 227 imgp->attr = &attr; 228 imgp->entry_addr = 0; 229 imgp->resident = 0; 230 imgp->vmspace_destroyed = 0; 231 imgp->interpreted = 0; 232 imgp->interpreter_name[0] = 0; 233 imgp->auxargs = NULL; 234 imgp->vp = NULL; 235 imgp->firstpage = NULL; 236 imgp->ps_strings = 0; 237 imgp->execpath = imgp->freepath = NULL; 238 imgp->execpathp = 0; 239 imgp->image_header = NULL; 240 241 interpret: 242 243 /* 244 * Translate the file name to a vnode. Unlock the cache entry to 245 * improve parallelism for programs exec'd in parallel. 246 */ 247 if ((error = nlookup(nd)) != 0) 248 goto exec_fail; 249 error = cache_vget(&nd->nl_nch, nd->nl_cred, LK_EXCLUSIVE, &imgp->vp); 250 KKASSERT(nd->nl_flags & NLC_NCPISLOCKED); 251 nd->nl_flags &= ~NLC_NCPISLOCKED; 252 cache_unlock(&nd->nl_nch); 253 if (error) 254 goto exec_fail; 255 256 /* 257 * Check file permissions (also 'opens' file). 258 * Include also the top level mount in the check. 259 */ 260 error = exec_check_permissions(imgp, nd->nl_nch.mount); 261 if (error) { 262 vn_unlock(imgp->vp); 263 goto exec_fail_dealloc; 264 } 265 266 error = exec_map_first_page(imgp); 267 vn_unlock(imgp->vp); 268 if (error) 269 goto exec_fail_dealloc; 270 271 imgp->proc->p_osrel = 0; 272 273 if (debug_execve_args && imgp->interpreted) { 274 kprintf(" target is interpreted -- recursive pass\n"); 275 kprintf(" interpreter: %s\n", imgp->interpreter_name); 276 print_execve_args(args); 277 } 278 279 /* 280 * If the current process has a special image activator it 281 * wants to try first, call it. For example, emulating shell 282 * scripts differently. 283 */ 284 error = -1; 285 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 286 error = img_first(imgp); 287 288 /* 289 * If the vnode has a registered vmspace, exec the vmspace 290 */ 291 if (error == -1 && imgp->vp->v_resident) { 292 error = exec_resident_imgact(imgp); 293 } 294 295 /* 296 * Loop through the list of image activators, calling each one. 297 * An activator returns -1 if there is no match, 0 on success, 298 * and an error otherwise. 299 */ 300 for (i = 0; error == -1 && execsw[i]; ++i) { 301 if (execsw[i]->ex_imgact == NULL || 302 execsw[i]->ex_imgact == img_first) { 303 continue; 304 } 305 error = (*execsw[i]->ex_imgact)(imgp); 306 } 307 308 if (error) { 309 if (error == -1) 310 error = ENOEXEC; 311 goto exec_fail_dealloc; 312 } 313 314 /* 315 * Special interpreter operation, cleanup and loop up to try to 316 * activate the interpreter. 317 */ 318 if (imgp->interpreted) { 319 exec_unmap_first_page(imgp); 320 nlookup_done(nd); 321 vrele(imgp->vp); 322 imgp->vp = NULL; 323 error = nlookup_init(nd, imgp->interpreter_name, UIO_SYSSPACE, 324 NLC_FOLLOW); 325 if (error) 326 goto exec_fail; 327 goto interpret; 328 } 329 330 /* 331 * Do the best to calculate the full path to the image file 332 */ 333 if (imgp->auxargs != NULL && 334 ((args->fname != NULL && args->fname[0] == '/') || 335 vn_fullpath(imgp->proc, 336 imgp->vp, 337 &imgp->execpath, 338 &imgp->freepath, 339 0) != 0)) 340 imgp->execpath = args->fname; 341 342 /* 343 * Copy out strings (args and env) and initialize stack base 344 */ 345 stack_base = exec_copyout_strings(imgp); 346 p->p_vmspace->vm_minsaddr = (char *)stack_base; 347 348 /* 349 * If custom stack fixup routine present for this process 350 * let it do the stack setup. If we are running a resident 351 * image there is no auxinfo or other image activator context 352 * so don't try to add fixups to the stack. 353 * 354 * Else stuff argument count as first item on stack 355 */ 356 if (p->p_sysent->sv_fixup && imgp->resident == 0) 357 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 358 else 359 suword(--stack_base, imgp->args->argc); 360 361 /* 362 * For security and other reasons, the file descriptor table cannot 363 * be shared after an exec. 364 */ 365 if (p->p_fd->fd_refcnt > 1) { 366 struct filedesc *tmp; 367 368 error = fdcopy(p, &tmp); 369 if (error != 0) 370 goto exec_fail; 371 fdfree(p, tmp); 372 } 373 374 /* 375 * For security and other reasons, signal handlers cannot 376 * be shared after an exec. The new proces gets a copy of the old 377 * handlers. In execsigs(), the new process will have its signals 378 * reset. 379 */ 380 ops = p->p_sigacts; 381 if (ops->ps_refcnt > 1) { 382 nps = kmalloc(sizeof(*nps), M_SUBPROC, M_WAITOK); 383 bcopy(ops, nps, sizeof(*nps)); 384 refcount_init(&nps->ps_refcnt, 1); 385 p->p_sigacts = nps; 386 if (refcount_release(&ops->ps_refcnt)) { 387 kfree(ops, M_SUBPROC); 388 ops = NULL; 389 } 390 } 391 392 /* 393 * For security and other reasons virtual kernels cannot be 394 * inherited by an exec. This also allows a virtual kernel 395 * to fork/exec unrelated applications. 396 */ 397 if (p->p_vkernel) 398 vkernel_exit(p); 399 400 /* Stop profiling */ 401 stopprofclock(p); 402 403 /* close files on exec */ 404 fdcloseexec(p); 405 406 /* reset caught signals */ 407 execsigs(p); 408 409 /* name this process - nameiexec(p, ndp) */ 410 len = min(nd->nl_nch.ncp->nc_nlen, MAXCOMLEN); 411 bcopy(nd->nl_nch.ncp->nc_name, p->p_comm, len); 412 p->p_comm[len] = 0; 413 bcopy(p->p_comm, lp->lwp_thread->td_comm, MAXCOMLEN+1); 414 415 /* 416 * mark as execed, wakeup the process that vforked (if any) and tell 417 * it that it now has its own resources back 418 */ 419 p->p_flags |= P_EXEC; 420 if (p->p_pptr && (p->p_flags & P_PPWAIT)) { 421 p->p_flags &= ~P_PPWAIT; 422 wakeup((caddr_t)p->p_pptr); 423 } 424 425 /* 426 * Implement image setuid/setgid. 427 * 428 * Don't honor setuid/setgid if the filesystem prohibits it or if 429 * the process is being traced. 430 */ 431 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 432 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 433 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 434 (p->p_flags & P_TRACED) == 0) { 435 /* 436 * Turn off syscall tracing for set-id programs, except for 437 * root. Record any set-id flags first to make sure that 438 * we do not regain any tracing during a possible block. 439 */ 440 setsugid(); 441 if (p->p_tracenode && ktrace_suid == 0 && 442 priv_check(td, PRIV_ROOT) != 0) { 443 ktrdestroy(&p->p_tracenode); 444 p->p_traceflag = 0; 445 } 446 /* Close any file descriptors 0..2 that reference procfs */ 447 setugidsafety(p); 448 /* Make sure file descriptors 0..2 are in use. */ 449 error = fdcheckstd(lp); 450 if (error != 0) 451 goto exec_fail_dealloc; 452 /* 453 * Set the new credentials. 454 */ 455 cratom(&p->p_ucred); 456 if (attr.va_mode & VSUID) 457 change_euid(attr.va_uid); 458 if (attr.va_mode & VSGID) 459 p->p_ucred->cr_gid = attr.va_gid; 460 461 /* 462 * Clear local varsym variables 463 */ 464 varsymset_clean(&p->p_varsymset); 465 } else { 466 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && 467 p->p_ucred->cr_gid == p->p_ucred->cr_rgid) 468 p->p_flags &= ~P_SUGID; 469 } 470 471 /* 472 * Implement correct POSIX saved-id behavior. 473 */ 474 if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || 475 p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { 476 cratom(&p->p_ucred); 477 p->p_ucred->cr_svuid = p->p_ucred->cr_uid; 478 p->p_ucred->cr_svgid = p->p_ucred->cr_gid; 479 } 480 481 /* 482 * Store the vp for use in procfs. Be sure to keep p_textvp 483 * consistent if we block during the switch-over. 484 */ 485 ovp = p->p_textvp; 486 vref(imgp->vp); /* ref new vp */ 487 p->p_textvp = imgp->vp; 488 if (ovp) /* release old vp */ 489 vrele(ovp); 490 491 /* Release old namecache handle to text file */ 492 if (p->p_textnch.ncp) 493 cache_drop(&p->p_textnch); 494 495 if (nd->nl_nch.mount) 496 cache_copy(&nd->nl_nch, &p->p_textnch); 497 498 /* 499 * Notify others that we exec'd, and clear the P_INEXEC flag 500 * as we're now a bona fide freshly-execed process. 501 */ 502 KNOTE(&p->p_klist, NOTE_EXEC); 503 p->p_flags &= ~P_INEXEC; 504 505 /* 506 * If tracing the process, trap to debugger so breakpoints 507 * can be set before the program executes. 508 */ 509 STOPEVENT(p, S_EXEC, 0); 510 511 if (p->p_flags & P_TRACED) 512 ksignal(p, SIGTRAP); 513 514 /* clear "fork but no exec" flag, as we _are_ execing */ 515 p->p_acflag &= ~AFORK; 516 517 /* Set values passed into the program in registers. */ 518 exec_setregs(imgp->entry_addr, (u_long)(uintptr_t)stack_base, 519 imgp->ps_strings); 520 521 /* Set the access time on the vnode */ 522 vn_mark_atime(imgp->vp, td); 523 524 /* 525 * Free any previous argument cache 526 */ 527 pa = p->p_args; 528 p->p_args = NULL; 529 if (pa && refcount_release(&pa->ar_ref)) { 530 kfree(pa, M_PARGS); 531 pa = NULL; 532 } 533 534 /* 535 * Cache arguments if they fit inside our allowance 536 */ 537 i = imgp->args->begin_envv - imgp->args->begin_argv; 538 if (sizeof(struct pargs) + i <= ps_arg_cache_limit) { 539 pa = kmalloc(sizeof(struct pargs) + i, M_PARGS, M_WAITOK); 540 refcount_init(&pa->ar_ref, 1); 541 pa->ar_length = i; 542 bcopy(imgp->args->begin_argv, pa->ar_args, i); 543 KKASSERT(p->p_args == NULL); 544 p->p_args = pa; 545 } 546 547 exec_fail_dealloc: 548 549 /* 550 * free various allocated resources 551 */ 552 if (imgp->firstpage) 553 exec_unmap_first_page(imgp); 554 555 if (imgp->vp) { 556 vrele(imgp->vp); 557 imgp->vp = NULL; 558 } 559 560 if (imgp->freepath) 561 kfree(imgp->freepath, M_TEMP); 562 563 if (error == 0) { 564 ++mycpu->gd_cnt.v_exec; 565 lwkt_reltoken(&p->p_token); 566 return (0); 567 } 568 569 exec_fail: 570 /* 571 * we're done here, clear P_INEXEC if we were the ones that 572 * set it. Otherwise if vmspace_destroyed is still set we 573 * raced another thread and that thread is responsible for 574 * clearing it. 575 */ 576 if (imgp->vmspace_destroyed & 2) 577 p->p_flags &= ~P_INEXEC; 578 lwkt_reltoken(&p->p_token); 579 if (imgp->vmspace_destroyed) { 580 /* 581 * Sorry, no more process anymore. exit gracefully. 582 * However we can't die right here, because our 583 * caller might have to clean up, so indicate a 584 * lethal error by returning -1. 585 */ 586 return(-1); 587 } else { 588 return(error); 589 } 590 } 591 592 /* 593 * execve() system call. 594 */ 595 int 596 sys_execve(struct execve_args *uap) 597 { 598 struct nlookupdata nd; 599 struct image_args args; 600 int error; 601 602 bzero(&args, sizeof(args)); 603 604 error = nlookup_init(&nd, uap->fname, UIO_USERSPACE, NLC_FOLLOW); 605 if (error == 0) { 606 error = exec_copyin_args(&args, uap->fname, PATH_USERSPACE, 607 uap->argv, uap->envv); 608 } 609 if (error == 0) 610 error = kern_execve(&nd, &args); 611 nlookup_done(&nd); 612 exec_free_args(&args); 613 614 if (error < 0) { 615 /* We hit a lethal error condition. Let's die now. */ 616 exit1(W_EXITCODE(0, SIGABRT)); 617 /* NOTREACHED */ 618 } 619 620 /* 621 * The syscall result is returned in registers to the new program. 622 * Linux will register %edx as an atexit function and we must be 623 * sure to set it to 0. XXX 624 */ 625 if (error == 0) 626 uap->sysmsg_result64 = 0; 627 628 return (error); 629 } 630 631 int 632 exec_map_page(struct image_params *imgp, vm_pindex_t pageno, 633 struct lwbuf **plwb, const char **pdata) 634 { 635 int rv; 636 vm_page_t ma; 637 vm_page_t m; 638 vm_object_t object; 639 640 /* 641 * The file has to be mappable. 642 */ 643 if ((object = imgp->vp->v_object) == NULL) 644 return (EIO); 645 646 if (pageno >= object->size) 647 return (EIO); 648 649 vm_object_hold(object); 650 m = vm_page_grab(object, pageno, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 651 while ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 652 ma = m; 653 654 /* 655 * get_pages unbusies all the requested pages except the 656 * primary page (at index 0 in this case). The primary 657 * page may have been wired during the pagein (e.g. by 658 * the buffer cache) so vnode_pager_freepage() must be 659 * used to properly release it. 660 */ 661 rv = vm_pager_get_page(object, &ma, 1); 662 m = vm_page_lookup(object, pageno); 663 664 if (rv != VM_PAGER_OK || m == NULL || m->valid == 0) { 665 if (m) { 666 vm_page_protect(m, VM_PROT_NONE); 667 vnode_pager_freepage(m); 668 } 669 vm_object_drop(object); 670 return EIO; 671 } 672 } 673 vm_page_hold(m); 674 vm_page_wakeup(m); /* unbusy the page */ 675 vm_object_drop(object); 676 677 *plwb = lwbuf_alloc(m, *plwb); 678 *pdata = (void *)lwbuf_kva(*plwb); 679 680 return (0); 681 } 682 683 /* 684 * Map the first page of an executable image. 685 * 686 * NOTE: If the mapping fails we have to NULL-out firstpage which may 687 * still be pointing to our supplied lwp structure. 688 */ 689 int 690 exec_map_first_page(struct image_params *imgp) 691 { 692 int err; 693 694 if (imgp->firstpage) 695 exec_unmap_first_page(imgp); 696 697 imgp->firstpage = &imgp->firstpage_cache; 698 err = exec_map_page(imgp, 0, &imgp->firstpage, &imgp->image_header); 699 700 if (err) { 701 imgp->firstpage = NULL; 702 return err; 703 } 704 705 return 0; 706 } 707 708 void 709 exec_unmap_page(struct lwbuf *lwb) 710 { 711 vm_page_t m; 712 713 crit_enter(); 714 if (lwb != NULL) { 715 m = lwbuf_page(lwb); 716 lwbuf_free(lwb); 717 vm_page_unhold(m); 718 } 719 crit_exit(); 720 } 721 722 void 723 exec_unmap_first_page(struct image_params *imgp) 724 { 725 exec_unmap_page(imgp->firstpage); 726 imgp->firstpage = NULL; 727 imgp->image_header = NULL; 728 } 729 730 /* 731 * Destroy old address space, and allocate a new stack 732 * The new stack is only SGROWSIZ large because it is grown 733 * automatically in trap.c. 734 * 735 * This is the point of no return. 736 */ 737 int 738 exec_new_vmspace(struct image_params *imgp, struct vmspace *vmcopy) 739 { 740 struct vmspace *vmspace = imgp->proc->p_vmspace; 741 vm_offset_t stack_addr = USRSTACK - maxssiz; 742 struct proc *p; 743 vm_map_t map; 744 int error; 745 746 /* 747 * Indicate that we cannot gracefully error out any more, kill 748 * any other threads present, and set P_INEXEC to indicate that 749 * we are now messing with the process structure proper. 750 * 751 * If killalllwps() races return an error which coupled with 752 * vmspace_destroyed will cause us to exit. This is what we 753 * want since another thread is patiently waiting for us to exit 754 * in that case. 755 */ 756 p = curproc; 757 imgp->vmspace_destroyed = 1; 758 759 if (curthread->td_proc->p_nthreads > 1) { 760 error = killalllwps(1); 761 if (error) 762 return (error); 763 } 764 imgp->vmspace_destroyed |= 2; /* we are responsible for P_INEXEC */ 765 p->p_flags |= P_INEXEC; 766 767 /* 768 * After setting P_INEXEC wait for any remaining references to 769 * the process (p) to go away. 770 * 771 * In particular, a vfork/exec sequence will replace p->p_vmspace 772 * and we must interlock anyone trying to access the space (aka 773 * procfs or sys_process.c calling procfs_domem()). 774 * 775 * If P_PPWAIT is set the parent vfork()'d and has a PHOLD() on us. 776 */ 777 PSTALL(p, "exec1", ((p->p_flags & P_PPWAIT) ? 1 : 0)); 778 779 /* 780 * Blow away entire process VM, if address space not shared, 781 * otherwise, create a new VM space so that other threads are 782 * not disrupted. If we are execing a resident vmspace we 783 * create a duplicate of it and remap the stack. 784 */ 785 map = &vmspace->vm_map; 786 if (vmcopy) { 787 vmspace_exec(imgp->proc, vmcopy); 788 vmspace = imgp->proc->p_vmspace; 789 pmap_remove_pages(vmspace_pmap(vmspace), stack_addr, USRSTACK); 790 map = &vmspace->vm_map; 791 } else if (vmspace->vm_sysref.refcnt == 1) { 792 shmexit(vmspace); 793 if (vmspace->vm_upcalls) 794 upc_release(vmspace, ONLY_LWP_IN_PROC(imgp->proc)); 795 pmap_remove_pages(vmspace_pmap(vmspace), 796 0, VM_MAX_USER_ADDRESS); 797 vm_map_remove(map, 0, VM_MAX_USER_ADDRESS); 798 } else { 799 vmspace_exec(imgp->proc, NULL); 800 vmspace = imgp->proc->p_vmspace; 801 map = &vmspace->vm_map; 802 } 803 804 /* Allocate a new stack */ 805 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 806 0, VM_PROT_ALL, VM_PROT_ALL, 0); 807 if (error) 808 return (error); 809 810 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 811 * VM_STACK case, but they are still used to monitor the size of the 812 * process stack so we can check the stack rlimit. 813 */ 814 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 815 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 816 817 return(0); 818 } 819 820 /* 821 * Copy out argument and environment strings from the old process 822 * address space into the temporary string buffer. 823 */ 824 int 825 exec_copyin_args(struct image_args *args, char *fname, 826 enum exec_path_segflg segflg, char **argv, char **envv) 827 { 828 char *argp, *envp; 829 int error = 0; 830 size_t length; 831 832 args->buf = objcache_get(exec_objcache, M_WAITOK); 833 if (args->buf == NULL) 834 return (ENOMEM); 835 args->begin_argv = args->buf; 836 args->endp = args->begin_argv; 837 args->space = ARG_MAX; 838 839 args->fname = args->buf + ARG_MAX; 840 841 /* 842 * Copy the file name. 843 */ 844 if (segflg == PATH_SYSSPACE) { 845 error = copystr(fname, args->fname, PATH_MAX, &length); 846 } else if (segflg == PATH_USERSPACE) { 847 error = copyinstr(fname, args->fname, PATH_MAX, &length); 848 } 849 850 /* 851 * Extract argument strings. argv may not be NULL. The argv 852 * array is terminated by a NULL entry. We special-case the 853 * situation where argv[0] is NULL by passing { filename, NULL } 854 * to the new program to guarentee that the interpreter knows what 855 * file to open in case we exec an interpreted file. Note that 856 * a NULL argv[0] terminates the argv[] array. 857 * 858 * XXX the special-casing of argv[0] is historical and needs to be 859 * revisited. 860 */ 861 if (argv == NULL) 862 error = EFAULT; 863 if (error == 0) { 864 while ((argp = (caddr_t)(intptr_t)fuword(argv++)) != NULL) { 865 if (argp == (caddr_t)-1) { 866 error = EFAULT; 867 break; 868 } 869 error = copyinstr(argp, args->endp, 870 args->space, &length); 871 if (error) { 872 if (error == ENAMETOOLONG) 873 error = E2BIG; 874 break; 875 } 876 args->space -= length; 877 args->endp += length; 878 args->argc++; 879 } 880 if (args->argc == 0 && error == 0) { 881 length = strlen(args->fname) + 1; 882 if (length > args->space) { 883 error = E2BIG; 884 } else { 885 bcopy(args->fname, args->endp, length); 886 args->space -= length; 887 args->endp += length; 888 args->argc++; 889 } 890 } 891 } 892 893 args->begin_envv = args->endp; 894 895 /* 896 * extract environment strings. envv may be NULL. 897 */ 898 if (envv && error == 0) { 899 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 900 if (envp == (caddr_t) -1) { 901 error = EFAULT; 902 break; 903 } 904 error = copyinstr(envp, args->endp, args->space, 905 &length); 906 if (error) { 907 if (error == ENAMETOOLONG) 908 error = E2BIG; 909 break; 910 } 911 args->space -= length; 912 args->endp += length; 913 args->envc++; 914 } 915 } 916 return (error); 917 } 918 919 void 920 exec_free_args(struct image_args *args) 921 { 922 if (args->buf) { 923 objcache_put(exec_objcache, args->buf); 924 args->buf = NULL; 925 } 926 } 927 928 /* 929 * Copy strings out to the new process address space, constructing 930 * new arg and env vector tables. Return a pointer to the base 931 * so that it can be used as the initial stack pointer. 932 */ 933 register_t * 934 exec_copyout_strings(struct image_params *imgp) 935 { 936 int argc, envc, sgap; 937 char **vectp; 938 char *stringp, *destp; 939 register_t *stack_base; 940 struct ps_strings *arginfo; 941 size_t execpath_len; 942 int szsigcode; 943 944 /* 945 * Calculate string base and vector table pointers. 946 * Also deal with signal trampoline code for this exec type. 947 */ 948 if (imgp->execpath != NULL && imgp->auxargs != NULL) 949 execpath_len = strlen(imgp->execpath) + 1; 950 else 951 execpath_len = 0; 952 arginfo = (struct ps_strings *)PS_STRINGS; 953 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 954 if (stackgap_random != 0) 955 sgap = ALIGN(karc4random() & (stackgap_random - 1)); 956 else 957 sgap = 0; 958 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - sgap - 959 roundup(execpath_len, sizeof(char *)) - 960 roundup((ARG_MAX - imgp->args->space), sizeof(char *)); 961 962 /* 963 * install sigcode 964 */ 965 if (szsigcode) 966 copyout(imgp->proc->p_sysent->sv_sigcode, 967 ((caddr_t)arginfo - szsigcode), szsigcode); 968 969 /* 970 * Copy the image path for the rtld 971 */ 972 if (execpath_len != 0) { 973 imgp->execpathp = (uintptr_t)arginfo 974 - szsigcode 975 - execpath_len; 976 copyout(imgp->execpath, (void *)imgp->execpathp, execpath_len); 977 } 978 979 /* 980 * If we have a valid auxargs ptr, prepare some room 981 * on the stack. 982 * 983 * The '+ 2' is for the null pointers at the end of each of the 984 * arg and env vector sets, and 'AT_COUNT*2' is room for the 985 * ELF Auxargs data. 986 */ 987 if (imgp->auxargs) { 988 vectp = (char **)(destp - (imgp->args->argc + 989 imgp->args->envc + 2 + (AT_COUNT * 2) + execpath_len) * 990 sizeof(char*)); 991 } else { 992 vectp = (char **)(destp - (imgp->args->argc + 993 imgp->args->envc + 2) * sizeof(char*)); 994 } 995 996 /* 997 * NOTE: don't bother aligning the stack here for GCC 2.x, it will 998 * be done in crt1.o. Note that GCC 3.x aligns the stack in main. 999 */ 1000 1001 /* 1002 * vectp also becomes our initial stack base 1003 */ 1004 stack_base = (register_t *)vectp; 1005 1006 stringp = imgp->args->begin_argv; 1007 argc = imgp->args->argc; 1008 envc = imgp->args->envc; 1009 1010 /* 1011 * Copy out strings - arguments and environment. 1012 */ 1013 copyout(stringp, destp, ARG_MAX - imgp->args->space); 1014 1015 /* 1016 * Fill in "ps_strings" struct for ps, w, etc. 1017 */ 1018 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1019 suword(&arginfo->ps_nargvstr, argc); 1020 1021 /* 1022 * Fill in argument portion of vector table. 1023 */ 1024 for (; argc > 0; --argc) { 1025 suword(vectp++, (long)(intptr_t)destp); 1026 while (*stringp++ != 0) 1027 destp++; 1028 destp++; 1029 } 1030 1031 /* a null vector table pointer separates the argp's from the envp's */ 1032 suword(vectp++, 0); 1033 1034 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1035 suword(&arginfo->ps_nenvstr, envc); 1036 1037 /* 1038 * Fill in environment portion of vector table. 1039 */ 1040 for (; envc > 0; --envc) { 1041 suword(vectp++, (long)(intptr_t)destp); 1042 while (*stringp++ != 0) 1043 destp++; 1044 destp++; 1045 } 1046 1047 /* end of vector table is a null pointer */ 1048 suword(vectp, 0); 1049 1050 return (stack_base); 1051 } 1052 1053 /* 1054 * Check permissions of file to execute. 1055 * Return 0 for success or error code on failure. 1056 */ 1057 int 1058 exec_check_permissions(struct image_params *imgp, struct mount *topmnt) 1059 { 1060 struct proc *p = imgp->proc; 1061 struct vnode *vp = imgp->vp; 1062 struct vattr *attr = imgp->attr; 1063 int error; 1064 1065 /* Get file attributes */ 1066 error = VOP_GETATTR(vp, attr); 1067 if (error) 1068 return (error); 1069 1070 /* 1071 * 1) Check if file execution is disabled for the filesystem that this 1072 * file resides on. 1073 * 2) Insure that at least one execute bit is on - otherwise root 1074 * will always succeed, and we don't want to happen unless the 1075 * file really is executable. 1076 * 3) Insure that the file is a regular file. 1077 */ 1078 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1079 ((topmnt != NULL) && (topmnt->mnt_flag & MNT_NOEXEC)) || 1080 ((attr->va_mode & 0111) == 0) || 1081 (attr->va_type != VREG)) { 1082 return (EACCES); 1083 } 1084 1085 /* 1086 * Zero length files can't be exec'd 1087 */ 1088 if (attr->va_size == 0) 1089 return (ENOEXEC); 1090 1091 /* 1092 * Check for execute permission to file based on current credentials. 1093 */ 1094 error = VOP_EACCESS(vp, VEXEC, p->p_ucred); 1095 if (error) 1096 return (error); 1097 1098 /* 1099 * Check number of open-for-writes on the file and deny execution 1100 * if there are any. 1101 */ 1102 if (vp->v_writecount) 1103 return (ETXTBSY); 1104 1105 /* 1106 * Call filesystem specific open routine, which allows us to read, 1107 * write, and mmap the file. Without the VOP_OPEN we can only 1108 * stat the file. 1109 */ 1110 error = VOP_OPEN(vp, FREAD, p->p_ucred, NULL); 1111 if (error) 1112 return (error); 1113 1114 return (0); 1115 } 1116 1117 /* 1118 * Exec handler registration 1119 */ 1120 int 1121 exec_register(const struct execsw *execsw_arg) 1122 { 1123 const struct execsw **es, **xs, **newexecsw; 1124 int count = 2; /* New slot and trailing NULL */ 1125 1126 if (execsw) 1127 for (es = execsw; *es; es++) 1128 count++; 1129 newexecsw = kmalloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1130 xs = newexecsw; 1131 if (execsw) 1132 for (es = execsw; *es; es++) 1133 *xs++ = *es; 1134 *xs++ = execsw_arg; 1135 *xs = NULL; 1136 if (execsw) 1137 kfree(execsw, M_TEMP); 1138 execsw = newexecsw; 1139 return 0; 1140 } 1141 1142 int 1143 exec_unregister(const struct execsw *execsw_arg) 1144 { 1145 const struct execsw **es, **xs, **newexecsw; 1146 int count = 1; 1147 1148 if (execsw == NULL) 1149 panic("unregister with no handlers left?"); 1150 1151 for (es = execsw; *es; es++) { 1152 if (*es == execsw_arg) 1153 break; 1154 } 1155 if (*es == NULL) 1156 return ENOENT; 1157 for (es = execsw; *es; es++) 1158 if (*es != execsw_arg) 1159 count++; 1160 newexecsw = kmalloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1161 xs = newexecsw; 1162 for (es = execsw; *es; es++) 1163 if (*es != execsw_arg) 1164 *xs++ = *es; 1165 *xs = NULL; 1166 if (execsw) 1167 kfree(execsw, M_TEMP); 1168 execsw = newexecsw; 1169 return 0; 1170 } 1171