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 * $DragonFly: src/sys/kern/kern_exec.c,v 1.64 2008/10/26 04:29:19 sephe Exp $ 28 */ 29 30 #include <sys/param.h> 31 #include <sys/systm.h> 32 #include <sys/sysproto.h> 33 #include <sys/kernel.h> 34 #include <sys/mount.h> 35 #include <sys/filedesc.h> 36 #include <sys/fcntl.h> 37 #include <sys/acct.h> 38 #include <sys/exec.h> 39 #include <sys/imgact.h> 40 #include <sys/imgact_elf.h> 41 #include <sys/kern_syscall.h> 42 #include <sys/wait.h> 43 #include <sys/malloc.h> 44 #include <sys/proc.h> 45 #include <sys/priv.h> 46 #include <sys/ktrace.h> 47 #include <sys/signalvar.h> 48 #include <sys/pioctl.h> 49 #include <sys/nlookup.h> 50 #include <sys/sysent.h> 51 #include <sys/shm.h> 52 #include <sys/sysctl.h> 53 #include <sys/vnode.h> 54 #include <sys/vmmeter.h> 55 #include <sys/aio.h> 56 #include <sys/libkern.h> 57 58 #include <cpu/lwbuf.h> 59 60 #include <vm/vm.h> 61 #include <vm/vm_param.h> 62 #include <sys/lock.h> 63 #include <vm/pmap.h> 64 #include <vm/vm_page.h> 65 #include <vm/vm_map.h> 66 #include <vm/vm_kern.h> 67 #include <vm/vm_extern.h> 68 #include <vm/vm_object.h> 69 #include <vm/vnode_pager.h> 70 #include <vm/vm_pager.h> 71 72 #include <sys/user.h> 73 #include <sys/reg.h> 74 75 #include <sys/thread2.h> 76 #include <sys/mplock2.h> 77 78 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 79 MALLOC_DEFINE(M_EXECARGS, "exec-args", "Exec arguments"); 80 81 static register_t *exec_copyout_strings (struct image_params *); 82 83 /* XXX This should be vm_size_t. */ 84 static u_long ps_strings = PS_STRINGS; 85 SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, ""); 86 87 /* XXX This should be vm_size_t. */ 88 static u_long usrstack = USRSTACK; 89 SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, ""); 90 91 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 92 SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 93 &ps_arg_cache_limit, 0, ""); 94 95 int ps_argsopen = 1; 96 SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, ""); 97 98 static int ktrace_suid = 0; 99 SYSCTL_INT(_kern, OID_AUTO, ktrace_suid, CTLFLAG_RW, &ktrace_suid, 0, ""); 100 101 void print_execve_args(struct image_args *args); 102 int debug_execve_args = 0; 103 SYSCTL_INT(_kern, OID_AUTO, debug_execve_args, CTLFLAG_RW, &debug_execve_args, 104 0, ""); 105 106 /* 107 * Exec arguments object cache 108 */ 109 static struct objcache *exec_objcache; 110 111 static 112 void 113 exec_objcache_init(void *arg __unused) 114 { 115 int cluster_limit; 116 117 cluster_limit = 16; /* up to this many objects */ 118 exec_objcache = objcache_create_mbacked( 119 M_EXECARGS, PATH_MAX + ARG_MAX, 120 &cluster_limit, 121 2, /* minimal magazine capacity */ 122 NULL, NULL, NULL); 123 } 124 SYSINIT(exec_objcache, SI_BOOT2_MACHDEP, SI_ORDER_ANY, exec_objcache_init, 0); 125 126 /* 127 * stackgap_random specifies if the stackgap should have a random size added 128 * to it. It must be a power of 2. If non-zero, the stack gap will be 129 * calculated as: ALIGN(karc4random() & (stackgap_random - 1)). 130 */ 131 static int stackgap_random = 1024; 132 static int 133 sysctl_kern_stackgap(SYSCTL_HANDLER_ARGS) 134 { 135 int error, new_val; 136 new_val = stackgap_random; 137 error = sysctl_handle_int(oidp, &new_val, 0, req); 138 if (error != 0 || req->newptr == NULL) 139 return (error); 140 if ((new_val < 0) || (new_val > 16 * PAGE_SIZE) || ! powerof2(new_val)) 141 return (EINVAL); 142 stackgap_random = new_val; 143 144 return(0); 145 } 146 147 SYSCTL_PROC(_kern, OID_AUTO, stackgap_random, CTLFLAG_RW|CTLTYPE_UINT, 148 0, 0, sysctl_kern_stackgap, "IU", "Max random stack gap (power of 2)"); 149 150 void 151 print_execve_args(struct image_args *args) 152 { 153 char *cp; 154 int ndx; 155 156 cp = args->begin_argv; 157 for (ndx = 0; ndx < args->argc; ndx++) { 158 kprintf("\targv[%d]: %s\n", ndx, cp); 159 while (*cp++ != '\0'); 160 } 161 for (ndx = 0; ndx < args->envc; ndx++) { 162 kprintf("\tenvv[%d]: %s\n", ndx, cp); 163 while (*cp++ != '\0'); 164 } 165 } 166 167 /* 168 * Each of the items is a pointer to a `const struct execsw', hence the 169 * double pointer here. 170 */ 171 static const struct execsw **execsw; 172 173 /* 174 * Replace current vmspace with a new binary. 175 * Returns 0 on success, > 0 on recoverable error (use as errno). 176 * Returns -1 on lethal error which demands killing of the current 177 * process! 178 */ 179 int 180 kern_execve(struct nlookupdata *nd, struct image_args *args) 181 { 182 struct thread *td = curthread; 183 struct lwp *lp = td->td_lwp; 184 struct proc *p = td->td_proc; 185 register_t *stack_base; 186 int error, len, i; 187 struct image_params image_params, *imgp; 188 struct vattr attr; 189 int (*img_first) (struct image_params *); 190 191 if (debug_execve_args) { 192 kprintf("%s()\n", __func__); 193 print_execve_args(args); 194 } 195 196 KKASSERT(p); 197 imgp = &image_params; 198 199 /* 200 * NOTE: P_INEXEC is handled by exec_new_vmspace() now. We make 201 * no modifications to the process at all until we get there. 202 * 203 * Note that multiple threads may be trying to exec at the same 204 * time. exec_new_vmspace() handles that too. 205 */ 206 207 /* 208 * Initialize part of the common data 209 */ 210 imgp->proc = p; 211 imgp->args = args; 212 imgp->attr = &attr; 213 imgp->entry_addr = 0; 214 imgp->resident = 0; 215 imgp->vmspace_destroyed = 0; 216 imgp->interpreted = 0; 217 imgp->interpreter_name[0] = 0; 218 imgp->auxargs = NULL; 219 imgp->vp = NULL; 220 imgp->firstpage = NULL; 221 imgp->ps_strings = 0; 222 imgp->image_header = NULL; 223 224 interpret: 225 226 /* 227 * Translate the file name to a vnode. Unlock the cache entry to 228 * improve parallelism for programs exec'd in parallel. 229 */ 230 if ((error = nlookup(nd)) != 0) 231 goto exec_fail; 232 error = cache_vget(&nd->nl_nch, nd->nl_cred, LK_EXCLUSIVE, &imgp->vp); 233 KKASSERT(nd->nl_flags & NLC_NCPISLOCKED); 234 nd->nl_flags &= ~NLC_NCPISLOCKED; 235 cache_unlock(&nd->nl_nch); 236 if (error) 237 goto exec_fail; 238 239 /* 240 * Check file permissions (also 'opens' file). 241 * Include also the top level mount in the check. 242 */ 243 error = exec_check_permissions(imgp, nd->nl_nch.mount); 244 if (error) { 245 vn_unlock(imgp->vp); 246 goto exec_fail_dealloc; 247 } 248 249 error = exec_map_first_page(imgp); 250 vn_unlock(imgp->vp); 251 if (error) 252 goto exec_fail_dealloc; 253 254 if (debug_execve_args && imgp->interpreted) { 255 kprintf(" target is interpreted -- recursive pass\n"); 256 kprintf(" interpreter: %s\n", imgp->interpreter_name); 257 print_execve_args(args); 258 } 259 260 /* 261 * If the current process has a special image activator it 262 * wants to try first, call it. For example, emulating shell 263 * scripts differently. 264 */ 265 error = -1; 266 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 267 error = img_first(imgp); 268 269 /* 270 * If the vnode has a registered vmspace, exec the vmspace 271 */ 272 if (error == -1 && imgp->vp->v_resident) { 273 error = exec_resident_imgact(imgp); 274 } 275 276 /* 277 * Loop through the list of image activators, calling each one. 278 * An activator returns -1 if there is no match, 0 on success, 279 * and an error otherwise. 280 */ 281 for (i = 0; error == -1 && execsw[i]; ++i) { 282 if (execsw[i]->ex_imgact == NULL || 283 execsw[i]->ex_imgact == img_first) { 284 continue; 285 } 286 error = (*execsw[i]->ex_imgact)(imgp); 287 } 288 289 if (error) { 290 if (error == -1) 291 error = ENOEXEC; 292 goto exec_fail_dealloc; 293 } 294 295 /* 296 * Special interpreter operation, cleanup and loop up to try to 297 * activate the interpreter. 298 */ 299 if (imgp->interpreted) { 300 exec_unmap_first_page(imgp); 301 nlookup_done(nd); 302 vrele(imgp->vp); 303 imgp->vp = NULL; 304 error = nlookup_init(nd, imgp->interpreter_name, UIO_SYSSPACE, 305 NLC_FOLLOW); 306 if (error) 307 goto exec_fail; 308 goto interpret; 309 } 310 311 /* 312 * Copy out strings (args and env) and initialize stack base 313 */ 314 stack_base = exec_copyout_strings(imgp); 315 p->p_vmspace->vm_minsaddr = (char *)stack_base; 316 317 /* 318 * If custom stack fixup routine present for this process 319 * let it do the stack setup. If we are running a resident 320 * image there is no auxinfo or other image activator context 321 * so don't try to add fixups to the stack. 322 * 323 * Else stuff argument count as first item on stack 324 */ 325 if (p->p_sysent->sv_fixup && imgp->resident == 0) 326 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 327 else 328 suword(--stack_base, imgp->args->argc); 329 330 /* 331 * For security and other reasons, the file descriptor table cannot 332 * be shared after an exec. 333 */ 334 if (p->p_fd->fd_refcnt > 1) { 335 struct filedesc *tmp; 336 337 tmp = fdcopy(p); 338 fdfree(p, tmp); 339 } 340 341 /* 342 * For security and other reasons, signal handlers cannot 343 * be shared after an exec. The new proces gets a copy of the old 344 * handlers. In execsigs(), the new process will have its signals 345 * reset. 346 */ 347 if (p->p_sigacts->ps_refcnt > 1) { 348 struct sigacts *newsigacts; 349 350 newsigacts = (struct sigacts *)kmalloc(sizeof(*newsigacts), 351 M_SUBPROC, M_WAITOK); 352 bcopy(p->p_sigacts, newsigacts, sizeof(*newsigacts)); 353 p->p_sigacts->ps_refcnt--; 354 p->p_sigacts = newsigacts; 355 p->p_sigacts->ps_refcnt = 1; 356 } 357 358 /* 359 * For security and other reasons virtual kernels cannot be 360 * inherited by an exec. This also allows a virtual kernel 361 * to fork/exec unrelated applications. 362 */ 363 if (p->p_vkernel) 364 vkernel_exit(p); 365 366 /* Stop profiling */ 367 stopprofclock(p); 368 369 /* close files on exec */ 370 fdcloseexec(p); 371 372 /* reset caught signals */ 373 execsigs(p); 374 375 /* name this process - nameiexec(p, ndp) */ 376 len = min(nd->nl_nch.ncp->nc_nlen, MAXCOMLEN); 377 bcopy(nd->nl_nch.ncp->nc_name, p->p_comm, len); 378 p->p_comm[len] = 0; 379 bcopy(p->p_comm, lp->lwp_thread->td_comm, MAXCOMLEN+1); 380 381 /* 382 * mark as execed, wakeup the process that vforked (if any) and tell 383 * it that it now has its own resources back 384 */ 385 p->p_flag |= P_EXEC; 386 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 387 p->p_flag &= ~P_PPWAIT; 388 wakeup((caddr_t)p->p_pptr); 389 } 390 391 /* 392 * Implement image setuid/setgid. 393 * 394 * Don't honor setuid/setgid if the filesystem prohibits it or if 395 * the process is being traced. 396 */ 397 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 398 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 399 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 400 (p->p_flag & P_TRACED) == 0) { 401 /* 402 * Turn off syscall tracing for set-id programs, except for 403 * root. Record any set-id flags first to make sure that 404 * we do not regain any tracing during a possible block. 405 */ 406 setsugid(); 407 if (p->p_tracenode && ktrace_suid == 0 && 408 priv_check(td, PRIV_ROOT) != 0) { 409 ktrdestroy(&p->p_tracenode); 410 p->p_traceflag = 0; 411 } 412 /* Close any file descriptors 0..2 that reference procfs */ 413 setugidsafety(p); 414 /* Make sure file descriptors 0..2 are in use. */ 415 error = fdcheckstd(lp); 416 if (error != 0) 417 goto exec_fail_dealloc; 418 /* 419 * Set the new credentials. 420 */ 421 cratom(&p->p_ucred); 422 if (attr.va_mode & VSUID) 423 change_euid(attr.va_uid); 424 if (attr.va_mode & VSGID) 425 p->p_ucred->cr_gid = attr.va_gid; 426 427 /* 428 * Clear local varsym variables 429 */ 430 varsymset_clean(&p->p_varsymset); 431 } else { 432 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && 433 p->p_ucred->cr_gid == p->p_ucred->cr_rgid) 434 p->p_flag &= ~P_SUGID; 435 } 436 437 /* 438 * Implement correct POSIX saved-id behavior. 439 */ 440 if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || 441 p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { 442 cratom(&p->p_ucred); 443 p->p_ucred->cr_svuid = p->p_ucred->cr_uid; 444 p->p_ucred->cr_svgid = p->p_ucred->cr_gid; 445 } 446 447 /* 448 * Store the vp for use in procfs 449 */ 450 if (p->p_textvp) /* release old reference */ 451 vrele(p->p_textvp); 452 p->p_textvp = imgp->vp; 453 vref(p->p_textvp); 454 455 /* Release old namecache handle to text file */ 456 if (p->p_textnch.ncp) 457 cache_drop(&p->p_textnch); 458 459 if (nd->nl_nch.mount) 460 cache_copy(&nd->nl_nch, &p->p_textnch); 461 462 /* 463 * Notify others that we exec'd, and clear the P_INEXEC flag 464 * as we're now a bona fide freshly-execed process. 465 */ 466 KNOTE(&p->p_klist, NOTE_EXEC); 467 p->p_flag &= ~P_INEXEC; 468 469 /* 470 * If tracing the process, trap to debugger so breakpoints 471 * can be set before the program executes. 472 */ 473 STOPEVENT(p, S_EXEC, 0); 474 475 if (p->p_flag & P_TRACED) 476 ksignal(p, SIGTRAP); 477 478 /* clear "fork but no exec" flag, as we _are_ execing */ 479 p->p_acflag &= ~AFORK; 480 481 /* Set values passed into the program in registers. */ 482 exec_setregs(imgp->entry_addr, (u_long)(uintptr_t)stack_base, 483 imgp->ps_strings); 484 485 /* Set the access time on the vnode */ 486 vn_mark_atime(imgp->vp, td); 487 488 /* Free any previous argument cache */ 489 if (p->p_args && --p->p_args->ar_ref == 0) 490 FREE(p->p_args, M_PARGS); 491 p->p_args = NULL; 492 493 /* Cache arguments if they fit inside our allowance */ 494 i = imgp->args->begin_envv - imgp->args->begin_argv; 495 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 496 MALLOC(p->p_args, struct pargs *, sizeof(struct pargs) + i, 497 M_PARGS, M_WAITOK); 498 p->p_args->ar_ref = 1; 499 p->p_args->ar_length = i; 500 bcopy(imgp->args->begin_argv, p->p_args->ar_args, i); 501 } 502 503 exec_fail_dealloc: 504 505 /* 506 * free various allocated resources 507 */ 508 if (imgp->firstpage) 509 exec_unmap_first_page(imgp); 510 511 if (imgp->vp) { 512 vrele(imgp->vp); 513 imgp->vp = NULL; 514 } 515 516 if (error == 0) { 517 ++mycpu->gd_cnt.v_exec; 518 return (0); 519 } 520 521 exec_fail: 522 /* 523 * we're done here, clear P_INEXEC if we were the ones that 524 * set it. Otherwise if vmspace_destroyed is still set we 525 * raced another thread and that thread is responsible for 526 * clearing it. 527 */ 528 if (imgp->vmspace_destroyed & 2) 529 p->p_flag &= ~P_INEXEC; 530 if (imgp->vmspace_destroyed) { 531 /* 532 * Sorry, no more process anymore. exit gracefully. 533 * However we can't die right here, because our 534 * caller might have to clean up, so indicate a 535 * lethal error by returning -1. 536 */ 537 return(-1); 538 } else { 539 return(error); 540 } 541 } 542 543 /* 544 * execve() system call. 545 * 546 * MPALMOSTSAFE 547 */ 548 int 549 sys_execve(struct execve_args *uap) 550 { 551 struct nlookupdata nd; 552 struct image_args args; 553 int error; 554 555 bzero(&args, sizeof(args)); 556 557 get_mplock(); 558 error = nlookup_init(&nd, uap->fname, UIO_USERSPACE, NLC_FOLLOW); 559 if (error == 0) { 560 error = exec_copyin_args(&args, uap->fname, PATH_USERSPACE, 561 uap->argv, uap->envv); 562 } 563 if (error == 0) 564 error = kern_execve(&nd, &args); 565 nlookup_done(&nd); 566 exec_free_args(&args); 567 568 if (error < 0) { 569 /* We hit a lethal error condition. Let's die now. */ 570 exit1(W_EXITCODE(0, SIGABRT)); 571 /* NOTREACHED */ 572 } 573 rel_mplock(); 574 575 /* 576 * The syscall result is returned in registers to the new program. 577 * Linux will register %edx as an atexit function and we must be 578 * sure to set it to 0. XXX 579 */ 580 if (error == 0) 581 uap->sysmsg_result64 = 0; 582 583 return (error); 584 } 585 586 int 587 exec_map_page(struct image_params *imgp, vm_pindex_t pageno, 588 struct lwbuf **plwb, const char **pdata) 589 { 590 int rv; 591 vm_page_t ma; 592 vm_page_t m; 593 vm_object_t object; 594 595 /* 596 * The file has to be mappable. 597 */ 598 if ((object = imgp->vp->v_object) == NULL) 599 return (EIO); 600 601 if (pageno >= object->size) 602 return (EIO); 603 604 m = vm_page_grab(object, pageno, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 605 606 lwkt_gettoken(&vm_token); 607 while ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 608 ma = m; 609 610 /* 611 * get_pages unbusies all the requested pages except the 612 * primary page (at index 0 in this case). The primary 613 * page may have been wired during the pagein (e.g. by 614 * the buffer cache) so vnode_pager_freepage() must be 615 * used to properly release it. 616 */ 617 rv = vm_pager_get_page(object, &ma, 1); 618 m = vm_page_lookup(object, pageno); 619 620 if (rv != VM_PAGER_OK || m == NULL || m->valid == 0) { 621 if (m) { 622 vm_page_protect(m, VM_PROT_NONE); 623 vnode_pager_freepage(m); 624 } 625 lwkt_reltoken(&vm_token); 626 return EIO; 627 } 628 } 629 vm_page_hold(m); /* requires vm_token to be held */ 630 vm_page_wakeup(m); /* unbusy the page */ 631 lwkt_reltoken(&vm_token); 632 633 *plwb = lwbuf_alloc(m, *plwb); 634 *pdata = (void *)lwbuf_kva(*plwb); 635 636 return (0); 637 } 638 639 int 640 exec_map_first_page(struct image_params *imgp) 641 { 642 int err; 643 644 if (imgp->firstpage) 645 exec_unmap_first_page(imgp); 646 647 imgp->firstpage = &imgp->firstpage_cache; 648 err = exec_map_page(imgp, 0, &imgp->firstpage, &imgp->image_header); 649 650 if (err) 651 return err; 652 653 return 0; 654 } 655 656 void 657 exec_unmap_page(struct lwbuf *lwb) 658 { 659 vm_page_t m; 660 661 crit_enter(); 662 if (lwb != NULL) { 663 m = lwbuf_page(lwb); 664 lwbuf_free(lwb); 665 vm_page_unhold(m); 666 } 667 crit_exit(); 668 } 669 670 void 671 exec_unmap_first_page(struct image_params *imgp) 672 { 673 exec_unmap_page(imgp->firstpage); 674 imgp->firstpage = NULL; 675 imgp->image_header = NULL; 676 } 677 678 /* 679 * Destroy old address space, and allocate a new stack 680 * The new stack is only SGROWSIZ large because it is grown 681 * automatically in trap.c. 682 * 683 * This is the point of no return. 684 */ 685 int 686 exec_new_vmspace(struct image_params *imgp, struct vmspace *vmcopy) 687 { 688 struct vmspace *vmspace = imgp->proc->p_vmspace; 689 vm_offset_t stack_addr = USRSTACK - maxssiz; 690 struct proc *p; 691 vm_map_t map; 692 int error; 693 694 /* 695 * Indicate that we cannot gracefully error out any more, kill 696 * any other threads present, and set P_INEXEC to indicate that 697 * we are now messing with the process structure proper. 698 * 699 * If killalllwps() races return an error which coupled with 700 * vmspace_destroyed will cause us to exit. This is what we 701 * want since another thread is patiently waiting for us to exit 702 * in that case. 703 */ 704 p = curproc; 705 imgp->vmspace_destroyed = 1; 706 707 if (curthread->td_proc->p_nthreads > 1) { 708 error = killalllwps(1); 709 if (error) 710 return (error); 711 } 712 imgp->vmspace_destroyed |= 2; /* we are responsible for P_INEXEC */ 713 p->p_flag |= P_INEXEC; 714 715 /* 716 * Prevent a pending AIO from modifying the new address space. 717 */ 718 aio_proc_rundown(imgp->proc); 719 720 /* 721 * Blow away entire process VM, if address space not shared, 722 * otherwise, create a new VM space so that other threads are 723 * not disrupted. If we are execing a resident vmspace we 724 * create a duplicate of it and remap the stack. 725 * 726 * The exitingcnt test is not strictly necessary but has been 727 * included for code sanity (to make the code more deterministic). 728 */ 729 map = &vmspace->vm_map; 730 if (vmcopy) { 731 vmspace_exec(imgp->proc, vmcopy); 732 vmspace = imgp->proc->p_vmspace; 733 pmap_remove_pages(vmspace_pmap(vmspace), stack_addr, USRSTACK); 734 map = &vmspace->vm_map; 735 } else if (vmspace->vm_sysref.refcnt == 1 && 736 vmspace->vm_exitingcnt == 0) { 737 shmexit(vmspace); 738 if (vmspace->vm_upcalls) 739 upc_release(vmspace, ONLY_LWP_IN_PROC(imgp->proc)); 740 pmap_remove_pages(vmspace_pmap(vmspace), 741 0, VM_MAX_USER_ADDRESS); 742 vm_map_remove(map, 0, VM_MAX_USER_ADDRESS); 743 } else { 744 vmspace_exec(imgp->proc, NULL); 745 vmspace = imgp->proc->p_vmspace; 746 map = &vmspace->vm_map; 747 } 748 749 /* Allocate a new stack */ 750 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 751 0, VM_PROT_ALL, VM_PROT_ALL, 0); 752 if (error) 753 return (error); 754 755 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 756 * VM_STACK case, but they are still used to monitor the size of the 757 * process stack so we can check the stack rlimit. 758 */ 759 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 760 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 761 762 return(0); 763 } 764 765 /* 766 * Copy out argument and environment strings from the old process 767 * address space into the temporary string buffer. 768 */ 769 int 770 exec_copyin_args(struct image_args *args, char *fname, 771 enum exec_path_segflg segflg, char **argv, char **envv) 772 { 773 char *argp, *envp; 774 int error = 0; 775 size_t length; 776 777 args->buf = objcache_get(exec_objcache, M_WAITOK); 778 if (args->buf == NULL) 779 return (ENOMEM); 780 args->begin_argv = args->buf; 781 args->endp = args->begin_argv; 782 args->space = ARG_MAX; 783 784 args->fname = args->buf + ARG_MAX; 785 786 /* 787 * Copy the file name. 788 */ 789 if (segflg == PATH_SYSSPACE) { 790 error = copystr(fname, args->fname, PATH_MAX, &length); 791 } else if (segflg == PATH_USERSPACE) { 792 error = copyinstr(fname, args->fname, PATH_MAX, &length); 793 } 794 795 /* 796 * Extract argument strings. argv may not be NULL. The argv 797 * array is terminated by a NULL entry. We special-case the 798 * situation where argv[0] is NULL by passing { filename, NULL } 799 * to the new program to guarentee that the interpreter knows what 800 * file to open in case we exec an interpreted file. Note that 801 * a NULL argv[0] terminates the argv[] array. 802 * 803 * XXX the special-casing of argv[0] is historical and needs to be 804 * revisited. 805 */ 806 if (argv == NULL) 807 error = EFAULT; 808 if (error == 0) { 809 while ((argp = (caddr_t)(intptr_t)fuword(argv++)) != NULL) { 810 if (argp == (caddr_t)-1) { 811 error = EFAULT; 812 break; 813 } 814 error = copyinstr(argp, args->endp, 815 args->space, &length); 816 if (error) { 817 if (error == ENAMETOOLONG) 818 error = E2BIG; 819 break; 820 } 821 args->space -= length; 822 args->endp += length; 823 args->argc++; 824 } 825 if (args->argc == 0 && error == 0) { 826 length = strlen(args->fname) + 1; 827 if (length > args->space) { 828 error = E2BIG; 829 } else { 830 bcopy(args->fname, args->endp, length); 831 args->space -= length; 832 args->endp += length; 833 args->argc++; 834 } 835 } 836 } 837 838 args->begin_envv = args->endp; 839 840 /* 841 * extract environment strings. envv may be NULL. 842 */ 843 if (envv && error == 0) { 844 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 845 if (envp == (caddr_t) -1) { 846 error = EFAULT; 847 break; 848 } 849 error = copyinstr(envp, args->endp, args->space, 850 &length); 851 if (error) { 852 if (error == ENAMETOOLONG) 853 error = E2BIG; 854 break; 855 } 856 args->space -= length; 857 args->endp += length; 858 args->envc++; 859 } 860 } 861 return (error); 862 } 863 864 void 865 exec_free_args(struct image_args *args) 866 { 867 if (args->buf) { 868 objcache_put(exec_objcache, args->buf); 869 args->buf = NULL; 870 } 871 } 872 873 /* 874 * Copy strings out to the new process address space, constructing 875 * new arg and env vector tables. Return a pointer to the base 876 * so that it can be used as the initial stack pointer. 877 */ 878 register_t * 879 exec_copyout_strings(struct image_params *imgp) 880 { 881 int argc, envc, sgap; 882 char **vectp; 883 char *stringp, *destp; 884 register_t *stack_base; 885 struct ps_strings *arginfo; 886 int szsigcode; 887 888 /* 889 * Calculate string base and vector table pointers. 890 * Also deal with signal trampoline code for this exec type. 891 */ 892 arginfo = (struct ps_strings *)PS_STRINGS; 893 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 894 if (stackgap_random != 0) 895 sgap = ALIGN(karc4random() & (stackgap_random - 1)); 896 else 897 sgap = 0; 898 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - sgap - 899 roundup((ARG_MAX - imgp->args->space), sizeof(char *)); 900 901 /* 902 * install sigcode 903 */ 904 if (szsigcode) 905 copyout(imgp->proc->p_sysent->sv_sigcode, 906 ((caddr_t)arginfo - szsigcode), szsigcode); 907 908 /* 909 * If we have a valid auxargs ptr, prepare some room 910 * on the stack. 911 * 912 * The '+ 2' is for the null pointers at the end of each of the 913 * arg and env vector sets, and 'AT_COUNT*2' is room for the 914 * ELF Auxargs data. 915 */ 916 if (imgp->auxargs) { 917 vectp = (char **)(destp - (imgp->args->argc + 918 imgp->args->envc + 2 + AT_COUNT * 2) * sizeof(char*)); 919 } else { 920 vectp = (char **)(destp - (imgp->args->argc + 921 imgp->args->envc + 2) * sizeof(char*)); 922 } 923 924 /* 925 * NOTE: don't bother aligning the stack here for GCC 2.x, it will 926 * be done in crt1.o. Note that GCC 3.x aligns the stack in main. 927 */ 928 929 /* 930 * vectp also becomes our initial stack base 931 */ 932 stack_base = (register_t *)vectp; 933 934 stringp = imgp->args->begin_argv; 935 argc = imgp->args->argc; 936 envc = imgp->args->envc; 937 938 /* 939 * Copy out strings - arguments and environment. 940 */ 941 copyout(stringp, destp, ARG_MAX - imgp->args->space); 942 943 /* 944 * Fill in "ps_strings" struct for ps, w, etc. 945 */ 946 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 947 suword(&arginfo->ps_nargvstr, argc); 948 949 /* 950 * Fill in argument portion of vector table. 951 */ 952 for (; argc > 0; --argc) { 953 suword(vectp++, (long)(intptr_t)destp); 954 while (*stringp++ != 0) 955 destp++; 956 destp++; 957 } 958 959 /* a null vector table pointer separates the argp's from the envp's */ 960 suword(vectp++, 0); 961 962 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 963 suword(&arginfo->ps_nenvstr, envc); 964 965 /* 966 * Fill in environment portion of vector table. 967 */ 968 for (; envc > 0; --envc) { 969 suword(vectp++, (long)(intptr_t)destp); 970 while (*stringp++ != 0) 971 destp++; 972 destp++; 973 } 974 975 /* end of vector table is a null pointer */ 976 suword(vectp, 0); 977 978 return (stack_base); 979 } 980 981 /* 982 * Check permissions of file to execute. 983 * Return 0 for success or error code on failure. 984 */ 985 int 986 exec_check_permissions(struct image_params *imgp, struct mount *topmnt) 987 { 988 struct proc *p = imgp->proc; 989 struct vnode *vp = imgp->vp; 990 struct vattr *attr = imgp->attr; 991 int error; 992 993 /* Get file attributes */ 994 error = VOP_GETATTR(vp, attr); 995 if (error) 996 return (error); 997 998 /* 999 * 1) Check if file execution is disabled for the filesystem that this 1000 * file resides on. 1001 * 2) Insure that at least one execute bit is on - otherwise root 1002 * will always succeed, and we don't want to happen unless the 1003 * file really is executable. 1004 * 3) Insure that the file is a regular file. 1005 */ 1006 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1007 ((topmnt != NULL) && (topmnt->mnt_flag & MNT_NOEXEC)) || 1008 ((attr->va_mode & 0111) == 0) || 1009 (attr->va_type != VREG)) { 1010 return (EACCES); 1011 } 1012 1013 /* 1014 * Zero length files can't be exec'd 1015 */ 1016 if (attr->va_size == 0) 1017 return (ENOEXEC); 1018 1019 /* 1020 * Check for execute permission to file based on current credentials. 1021 */ 1022 error = VOP_EACCESS(vp, VEXEC, p->p_ucred); 1023 if (error) 1024 return (error); 1025 1026 /* 1027 * Check number of open-for-writes on the file and deny execution 1028 * if there are any. 1029 */ 1030 if (vp->v_writecount) 1031 return (ETXTBSY); 1032 1033 /* 1034 * Call filesystem specific open routine, which allows us to read, 1035 * write, and mmap the file. Without the VOP_OPEN we can only 1036 * stat the file. 1037 */ 1038 error = VOP_OPEN(vp, FREAD, p->p_ucred, NULL); 1039 if (error) 1040 return (error); 1041 1042 return (0); 1043 } 1044 1045 /* 1046 * Exec handler registration 1047 */ 1048 int 1049 exec_register(const struct execsw *execsw_arg) 1050 { 1051 const struct execsw **es, **xs, **newexecsw; 1052 int count = 2; /* New slot and trailing NULL */ 1053 1054 if (execsw) 1055 for (es = execsw; *es; es++) 1056 count++; 1057 newexecsw = kmalloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1058 xs = newexecsw; 1059 if (execsw) 1060 for (es = execsw; *es; es++) 1061 *xs++ = *es; 1062 *xs++ = execsw_arg; 1063 *xs = NULL; 1064 if (execsw) 1065 kfree(execsw, M_TEMP); 1066 execsw = newexecsw; 1067 return 0; 1068 } 1069 1070 int 1071 exec_unregister(const struct execsw *execsw_arg) 1072 { 1073 const struct execsw **es, **xs, **newexecsw; 1074 int count = 1; 1075 1076 if (execsw == NULL) 1077 panic("unregister with no handlers left?"); 1078 1079 for (es = execsw; *es; es++) { 1080 if (*es == execsw_arg) 1081 break; 1082 } 1083 if (*es == NULL) 1084 return ENOENT; 1085 for (es = execsw; *es; es++) 1086 if (*es != execsw_arg) 1087 count++; 1088 newexecsw = kmalloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1089 xs = newexecsw; 1090 for (es = execsw; *es; es++) 1091 if (*es != execsw_arg) 1092 *xs++ = *es; 1093 *xs = NULL; 1094 if (execsw) 1095 kfree(execsw, M_TEMP); 1096 execsw = newexecsw; 1097 return 0; 1098 } 1099