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