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 1.17 2003/11/18 01:15:42 dillon 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/signalvar.h> 46 #include <sys/pioctl.h> 47 #include <sys/namei.h> 48 #include <sys/sysent.h> 49 #include <sys/shm.h> 50 #include <sys/sysctl.h> 51 #include <sys/vnode.h> 52 #include <sys/aio.h> 53 54 #include <vm/vm.h> 55 #include <vm/vm_param.h> 56 #include <sys/lock.h> 57 #include <vm/pmap.h> 58 #include <vm/vm_page.h> 59 #include <vm/vm_map.h> 60 #include <vm/vm_kern.h> 61 #include <vm/vm_extern.h> 62 #include <vm/vm_object.h> 63 #include <vm/vm_pager.h> 64 65 #include <sys/user.h> 66 #include <machine/reg.h> 67 68 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 69 70 static register_t *exec_copyout_strings (struct image_params *); 71 72 /* XXX This should be vm_size_t. */ 73 static u_long ps_strings = PS_STRINGS; 74 SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, ""); 75 76 /* XXX This should be vm_size_t. */ 77 static u_long usrstack = USRSTACK; 78 SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, ""); 79 80 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 81 SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 82 &ps_arg_cache_limit, 0, ""); 83 84 int ps_argsopen = 1; 85 SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, ""); 86 87 void print_execve_args(struct image_args *args); 88 int debug_execve_args = 0; 89 SYSCTL_INT(_kern, OID_AUTO, debug_execve_args, CTLFLAG_RW, &debug_execve_args, 90 0, ""); 91 92 void 93 print_execve_args(struct image_args *args) 94 { 95 char *cp; 96 int ndx; 97 98 cp = args->begin_argv; 99 for (ndx = 0; ndx < args->argc; ndx++) { 100 printf("\targv[%d]: %s\n", ndx, cp); 101 while (*cp++ != '\0'); 102 } 103 for (ndx = 0; ndx < args->envc; ndx++) { 104 printf("\tenvv[%d]: %s\n", ndx, cp); 105 while (*cp++ != '\0'); 106 } 107 } 108 109 /* 110 * Each of the items is a pointer to a `const struct execsw', hence the 111 * double pointer here. 112 */ 113 static const struct execsw **execsw; 114 115 int 116 kern_execve(struct nameidata *ndp, struct image_args *args) 117 { 118 struct thread *td = curthread; 119 struct proc *p = td->td_proc; 120 register_t *stack_base; 121 int error, len, i; 122 struct image_params image_params, *imgp; 123 struct vattr attr; 124 int (*img_first) (struct image_params *); 125 126 if (debug_execve_args) { 127 printf("%s()\n", __func__); 128 print_execve_args(args); 129 } 130 131 KKASSERT(p); 132 imgp = &image_params; 133 134 /* 135 * Lock the process and set the P_INEXEC flag to indicate that 136 * it should be left alone until we're done here. This is 137 * necessary to avoid race conditions - e.g. in ptrace() - 138 * that might allow a local user to illicitly obtain elevated 139 * privileges. 140 */ 141 p->p_flag |= P_INEXEC; 142 143 /* 144 * Initialize part of the common data 145 */ 146 imgp->proc = p; 147 imgp->args = args; 148 imgp->attr = &attr; 149 imgp->entry_addr = 0; 150 imgp->vmspace_destroyed = 0; 151 imgp->interpreted = 0; 152 imgp->interpreter_name[0] = 0; 153 imgp->auxargs = NULL; 154 imgp->vp = NULL; 155 imgp->firstpage = NULL; 156 imgp->ps_strings = 0; 157 158 /* 159 * Allocate temporary demand zeroed space for argument and 160 * environment strings 161 */ 162 imgp->image_header = (char *)kmem_alloc_wait(exec_map, PAGE_SIZE); 163 if (imgp->image_header == NULL) { 164 error = ENOMEM; 165 goto exec_fail; 166 } 167 168 interpret: 169 170 /* 171 * Translate the file name. namei() returns a vnode pointer 172 * in ni_vp amoung other things. 173 */ 174 error = namei(ndp); 175 if (error) { 176 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->image_header, 177 PAGE_SIZE); 178 goto exec_fail; 179 } 180 181 imgp->vp = ndp->ni_vp; 182 183 /* 184 * Check file permissions (also 'opens' file) 185 */ 186 error = exec_check_permissions(imgp); 187 if (error) { 188 VOP_UNLOCK(imgp->vp, 0, td); 189 goto exec_fail_dealloc; 190 } 191 192 error = exec_map_first_page(imgp); 193 VOP_UNLOCK(imgp->vp, 0, td); 194 if (error) 195 goto exec_fail_dealloc; 196 197 if (debug_execve_args && imgp->interpreted) { 198 printf(" target is interpreted -- recursive pass\n"); 199 printf(" interpreter: %s\n", imgp->interpreter_name); 200 print_execve_args(args); 201 } 202 203 /* 204 * If the current process has a special image activator it 205 * wants to try first, call it. For example, emulating shell 206 * scripts differently. 207 */ 208 error = -1; 209 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 210 error = img_first(imgp); 211 212 /* 213 * Loop through the list of image activators, calling each one. 214 * An activator returns -1 if there is no match, 0 on success, 215 * and an error otherwise. 216 */ 217 for (i = 0; error == -1 && execsw[i]; ++i) { 218 if (execsw[i]->ex_imgact == NULL || 219 execsw[i]->ex_imgact == img_first) { 220 continue; 221 } 222 error = (*execsw[i]->ex_imgact)(imgp); 223 } 224 225 if (error) { 226 if (error == -1) 227 error = ENOEXEC; 228 goto exec_fail_dealloc; 229 } 230 231 /* 232 * Special interpreter operation, cleanup and loop up to try to 233 * activate the interpreter. 234 */ 235 if (imgp->interpreted) { 236 exec_unmap_first_page(imgp); 237 /* free name buffer and old vnode */ 238 NDFREE(ndp, NDF_ONLY_PNBUF); 239 vrele(ndp->ni_vp); 240 /* set new name to that of the interpreter */ 241 NDINIT(ndp, NAMEI_LOOKUP, 242 CNP_LOCKLEAF | CNP_FOLLOW | CNP_SAVENAME, 243 UIO_SYSSPACE, imgp->interpreter_name, td); 244 goto interpret; 245 } 246 247 /* 248 * Copy out strings (args and env) and initialize stack base 249 */ 250 stack_base = exec_copyout_strings(imgp); 251 p->p_vmspace->vm_minsaddr = (char *)stack_base; 252 253 /* 254 * If custom stack fixup routine present for this process 255 * let it do the stack setup. 256 * Else stuff argument count as first item on stack 257 */ 258 if (p->p_sysent->sv_fixup) 259 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 260 else 261 suword(--stack_base, imgp->args->argc); 262 263 /* 264 * For security and other reasons, the file descriptor table cannot 265 * be shared after an exec. 266 */ 267 if (p->p_fd->fd_refcnt > 1) { 268 struct filedesc *tmp; 269 270 tmp = fdcopy(p); 271 fdfree(p); 272 p->p_fd = tmp; 273 } 274 275 /* 276 * For security and other reasons, signal handlers cannot 277 * be shared after an exec. The new proces gets a copy of the old 278 * handlers. In execsigs(), the new process will have its signals 279 * reset. 280 */ 281 if (p->p_procsig->ps_refcnt > 1) { 282 struct procsig *newprocsig; 283 284 MALLOC(newprocsig, struct procsig *, sizeof(struct procsig), 285 M_SUBPROC, M_WAITOK); 286 bcopy(p->p_procsig, newprocsig, sizeof(*newprocsig)); 287 p->p_procsig->ps_refcnt--; 288 p->p_procsig = newprocsig; 289 p->p_procsig->ps_refcnt = 1; 290 if (p->p_sigacts == &p->p_addr->u_sigacts) 291 panic("shared procsig but private sigacts?"); 292 293 p->p_addr->u_sigacts = *p->p_sigacts; 294 p->p_sigacts = &p->p_addr->u_sigacts; 295 } 296 297 /* Stop profiling */ 298 stopprofclock(p); 299 300 /* close files on exec */ 301 fdcloseexec(p); 302 303 /* reset caught signals */ 304 execsigs(p); 305 306 /* name this process - nameiexec(p, ndp) */ 307 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 308 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 309 p->p_comm[len] = 0; 310 311 /* 312 * mark as execed, wakeup the process that vforked (if any) and tell 313 * it that it now has its own resources back 314 */ 315 p->p_flag |= P_EXEC; 316 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 317 p->p_flag &= ~P_PPWAIT; 318 wakeup((caddr_t)p->p_pptr); 319 } 320 321 /* 322 * Implement image setuid/setgid. 323 * 324 * Don't honor setuid/setgid if the filesystem prohibits it or if 325 * the process is being traced. 326 */ 327 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 328 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 329 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 330 (p->p_flag & P_TRACED) == 0) { 331 /* 332 * Turn off syscall tracing for set-id programs, except for 333 * root. Record any set-id flags first to make sure that 334 * we do not regain any tracing during a possible block. 335 */ 336 setsugid(); 337 if (p->p_tracep && suser(td)) { 338 struct vnode *vtmp; 339 340 if ((vtmp = p->p_tracep) != NULL) { 341 p->p_tracep = NULL; 342 p->p_traceflag = 0; 343 vrele(vtmp); 344 } 345 } 346 /* Close any file descriptors 0..2 that reference procfs */ 347 setugidsafety(p); 348 /* Make sure file descriptors 0..2 are in use. */ 349 error = fdcheckstd(p); 350 if (error != 0) 351 goto exec_fail_dealloc; 352 /* 353 * Set the new credentials. 354 */ 355 cratom(&p->p_ucred); 356 if (attr.va_mode & VSUID) 357 change_euid(attr.va_uid); 358 if (attr.va_mode & VSGID) 359 p->p_ucred->cr_gid = attr.va_gid; 360 361 /* 362 * Clear local varsym variables 363 */ 364 varsymset_clean(&p->p_varsymset); 365 } else { 366 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && 367 p->p_ucred->cr_gid == p->p_ucred->cr_rgid) 368 p->p_flag &= ~P_SUGID; 369 } 370 371 /* 372 * Implement correct POSIX saved-id behavior. 373 */ 374 if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || 375 p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { 376 cratom(&p->p_ucred); 377 p->p_ucred->cr_svuid = p->p_ucred->cr_uid; 378 p->p_ucred->cr_svgid = p->p_ucred->cr_gid; 379 } 380 381 /* 382 * Store the vp for use in procfs 383 */ 384 if (p->p_textvp) /* release old reference */ 385 vrele(p->p_textvp); 386 VREF(ndp->ni_vp); 387 p->p_textvp = ndp->ni_vp; 388 389 /* 390 * Notify others that we exec'd, and clear the P_INEXEC flag 391 * as we're now a bona fide freshly-execed process. 392 */ 393 KNOTE(&p->p_klist, NOTE_EXEC); 394 p->p_flag &= ~P_INEXEC; 395 396 /* 397 * If tracing the process, trap to debugger so breakpoints 398 * can be set before the program executes. 399 */ 400 STOPEVENT(p, S_EXEC, 0); 401 402 if (p->p_flag & P_TRACED) 403 psignal(p, SIGTRAP); 404 405 /* clear "fork but no exec" flag, as we _are_ execing */ 406 p->p_acflag &= ~AFORK; 407 408 /* Set values passed into the program in registers. */ 409 setregs(p, imgp->entry_addr, (u_long)(uintptr_t)stack_base, 410 imgp->ps_strings); 411 412 /* Free any previous argument cache */ 413 if (p->p_args && --p->p_args->ar_ref == 0) 414 FREE(p->p_args, M_PARGS); 415 p->p_args = NULL; 416 417 /* Cache arguments if they fit inside our allowance */ 418 i = imgp->args->begin_envv - imgp->args->begin_argv; 419 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 420 MALLOC(p->p_args, struct pargs *, sizeof(struct pargs) + i, 421 M_PARGS, M_WAITOK); 422 p->p_args->ar_ref = 1; 423 p->p_args->ar_length = i; 424 bcopy(imgp->args->begin_argv, p->p_args->ar_args, i); 425 } 426 427 exec_fail_dealloc: 428 429 /* 430 * free various allocated resources 431 */ 432 if (imgp->firstpage) 433 exec_unmap_first_page(imgp); 434 435 if (imgp->image_header != NULL) 436 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->image_header, 437 PAGE_SIZE); 438 439 if (imgp->vp) { 440 NDFREE(ndp, NDF_ONLY_PNBUF); 441 vrele(imgp->vp); 442 } 443 444 if (error == 0) 445 return (0); 446 447 exec_fail: 448 /* we're done here, clear P_INEXEC */ 449 p->p_flag &= ~P_INEXEC; 450 if (imgp->vmspace_destroyed) { 451 /* sorry, no more process anymore. exit gracefully */ 452 exit1(W_EXITCODE(0, SIGABRT)); 453 /* NOT REACHED */ 454 return(0); 455 } else { 456 return(error); 457 } 458 } 459 460 /* 461 * execve() system call. 462 */ 463 int 464 execve(struct execve_args *uap) 465 { 466 struct thread *td = curthread; 467 struct nameidata nd; 468 struct image_args args; 469 int error; 470 471 NDINIT(&nd, NAMEI_LOOKUP, CNP_LOCKLEAF | CNP_FOLLOW | CNP_SAVENAME, 472 UIO_USERSPACE, uap->fname, td); 473 474 error = exec_copyin_args(&args, uap->fname, PATH_USERSPACE, 475 uap->argv, uap->envv); 476 if (error == 0) 477 error = kern_execve(&nd, &args); 478 479 exec_free_args(&args); 480 481 /* 482 * The syscall result is returned in registers to the new program. 483 * Linux will register %edx as an atexit function and we must be 484 * sure to set it to 0. XXX 485 */ 486 if (error == 0) 487 uap->sysmsg_result64 = 0; 488 489 return (error); 490 } 491 492 int 493 exec_map_first_page(struct image_params *imgp) 494 { 495 int s, rv, i; 496 int initial_pagein; 497 vm_page_t ma[VM_INITIAL_PAGEIN]; 498 vm_object_t object; 499 500 501 if (imgp->firstpage) { 502 exec_unmap_first_page(imgp); 503 } 504 505 VOP_GETVOBJECT(imgp->vp, &object); 506 s = splvm(); 507 508 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 509 510 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 511 initial_pagein = VM_INITIAL_PAGEIN; 512 if (initial_pagein > object->size) 513 initial_pagein = object->size; 514 for (i = 1; i < initial_pagein; i++) { 515 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 516 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy) 517 break; 518 if (ma[i]->valid) 519 break; 520 vm_page_busy(ma[i]); 521 } else { 522 ma[i] = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 523 if (ma[i] == NULL) 524 break; 525 } 526 } 527 initial_pagein = i; 528 529 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 530 ma[0] = vm_page_lookup(object, 0); 531 532 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || (ma[0]->valid == 0)) { 533 if (ma[0]) { 534 vm_page_protect(ma[0], VM_PROT_NONE); 535 vm_page_free(ma[0]); 536 } 537 splx(s); 538 return EIO; 539 } 540 } 541 542 vm_page_wire(ma[0]); 543 vm_page_wakeup(ma[0]); 544 splx(s); 545 546 pmap_kenter((vm_offset_t) imgp->image_header, VM_PAGE_TO_PHYS(ma[0])); 547 imgp->firstpage = ma[0]; 548 549 return 0; 550 } 551 552 void 553 exec_unmap_first_page(imgp) 554 struct image_params *imgp; 555 { 556 if (imgp->firstpage) { 557 pmap_kremove((vm_offset_t) imgp->image_header); 558 vm_page_unwire(imgp->firstpage, 1); 559 imgp->firstpage = NULL; 560 } 561 } 562 563 /* 564 * Destroy old address space, and allocate a new stack 565 * The new stack is only SGROWSIZ large because it is grown 566 * automatically in trap.c. 567 */ 568 int 569 exec_new_vmspace(imgp) 570 struct image_params *imgp; 571 { 572 int error; 573 struct vmspace *vmspace = imgp->proc->p_vmspace; 574 vm_offset_t stack_addr = USRSTACK - maxssiz; 575 vm_map_t map = &vmspace->vm_map; 576 577 imgp->vmspace_destroyed = 1; 578 579 /* 580 * Prevent a pending AIO from modifying the new address space. 581 */ 582 aio_proc_rundown(imgp->proc); 583 584 /* 585 * Blow away entire process VM, if address space not shared, 586 * otherwise, create a new VM space so that other threads are 587 * not disrupted 588 */ 589 if (vmspace->vm_refcnt == 1) { 590 shmexit(vmspace); 591 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); 592 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); 593 } else { 594 vmspace_exec(imgp->proc); 595 vmspace = imgp->proc->p_vmspace; 596 map = &vmspace->vm_map; 597 } 598 599 /* Allocate a new stack */ 600 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 601 VM_PROT_ALL, VM_PROT_ALL, 0); 602 if (error) 603 return (error); 604 605 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 606 * VM_STACK case, but they are still used to monitor the size of the 607 * process stack so we can check the stack rlimit. 608 */ 609 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 610 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 611 612 return(0); 613 } 614 615 /* 616 * Copy out argument and environment strings from the old process 617 * address space into the temporary string buffer. 618 */ 619 int 620 exec_copyin_args(struct image_args *args, char *fname, 621 enum exec_path_segflg segflg, char **argv, char **envv) 622 { 623 char *argp, *envp; 624 int error = 0; 625 size_t length; 626 627 bzero(args, sizeof(*args)); 628 args->buf = (char *) kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 629 if (args->buf == NULL) 630 return (ENOMEM); 631 args->begin_argv = args->buf; 632 args->endp = args->begin_argv; 633 args->space = ARG_MAX; 634 635 args->fname = args->buf + ARG_MAX; 636 637 /* 638 * Copy the file name. 639 */ 640 if (segflg == PATH_SYSSPACE) { 641 error = copystr(fname, args->fname, PATH_MAX, &length); 642 } else if (segflg == PATH_USERSPACE) { 643 error = copyinstr(fname, args->fname, PATH_MAX, &length); 644 } 645 646 /* 647 * extract argument strings 648 */ 649 650 if (argv && error == 0) { 651 /* 652 * The argv0 argument for execv() is allowed to be NULL, 653 * in which case we use our filename as argv[0]. 654 * This guarantees that 655 * the interpreter knows what file to open in the case 656 * that we exec an interpreted file. 657 */ 658 argp = (caddr_t) (intptr_t) fuword(argv); 659 if (argp == NULL) { 660 length = strlen(args->fname) + 1; 661 KKASSERT(length <= args->space); 662 bcopy(args->fname, args->endp, length); 663 args->space -= length; 664 args->endp += length; 665 args->argc++; 666 argv++; 667 } 668 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 669 if (argp == (caddr_t) -1) { 670 error = EFAULT; 671 goto cleanup; 672 } 673 error = copyinstr(argp, args->endp, 674 args->space, &length); 675 if (error == ENAMETOOLONG) 676 error = E2BIG; 677 if (error) 678 goto cleanup; 679 args->space -= length; 680 args->endp += length; 681 args->argc++; 682 } 683 } 684 685 args->begin_envv = args->endp; 686 687 /* 688 * extract environment strings 689 */ 690 if (envv && error == 0) { 691 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 692 if (envp == (caddr_t) -1) { 693 error = EFAULT; 694 goto cleanup; 695 } 696 error = copyinstr(envp, args->endp, args->space, 697 &length); 698 if (error == ENAMETOOLONG) 699 error = E2BIG; 700 if (error) 701 goto cleanup; 702 args->space -= length; 703 args->endp += length; 704 args->envc++; 705 } 706 } 707 708 cleanup: 709 return (error); 710 } 711 712 void 713 exec_free_args(struct image_args *args) 714 { 715 if (args->buf) { 716 kmem_free_wakeup(exec_map, 717 (vm_offset_t)args->buf, PATH_MAX + ARG_MAX); 718 args->buf = NULL; 719 } 720 } 721 722 /* 723 * Copy strings out to the new process address space, constructing 724 * new arg and env vector tables. Return a pointer to the base 725 * so that it can be used as the initial stack pointer. 726 */ 727 register_t * 728 exec_copyout_strings(struct image_params *imgp) 729 { 730 int argc, envc; 731 char **vectp; 732 char *stringp, *destp; 733 register_t *stack_base; 734 struct ps_strings *arginfo; 735 int szsigcode; 736 737 /* 738 * Calculate string base and vector table pointers. 739 * Also deal with signal trampoline code for this exec type. 740 */ 741 arginfo = (struct ps_strings *)PS_STRINGS; 742 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 743 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 744 roundup((ARG_MAX - imgp->args->space), sizeof(char *)); 745 746 /* 747 * install sigcode 748 */ 749 if (szsigcode) 750 copyout(imgp->proc->p_sysent->sv_sigcode, 751 ((caddr_t)arginfo - szsigcode), szsigcode); 752 753 /* 754 * If we have a valid auxargs ptr, prepare some room 755 * on the stack. 756 * 757 * The '+ 2' is for the null pointers at the end of each of the 758 * arg and env vector sets, and 'AT_COUNT*2' is room for the 759 * ELF Auxargs data. 760 */ 761 if (imgp->auxargs) { 762 vectp = (char **)(destp - (imgp->args->argc + 763 imgp->args->envc + 2 + AT_COUNT * 2) * sizeof(char*)); 764 } else { 765 vectp = (char **)(destp - (imgp->args->argc + 766 imgp->args->envc + 2) * sizeof(char*)); 767 } 768 769 /* 770 * NOTE: don't bother aligning the stack here for GCC 2.x, it will 771 * be done in crt1.o. Note that GCC 3.x aligns the stack in main. 772 */ 773 774 /* 775 * vectp also becomes our initial stack base 776 */ 777 stack_base = (register_t *)vectp; 778 779 stringp = imgp->args->begin_argv; 780 argc = imgp->args->argc; 781 envc = imgp->args->envc; 782 783 /* 784 * Copy out strings - arguments and environment. 785 */ 786 copyout(stringp, destp, ARG_MAX - imgp->args->space); 787 788 /* 789 * Fill in "ps_strings" struct for ps, w, etc. 790 */ 791 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 792 suword(&arginfo->ps_nargvstr, argc); 793 794 /* 795 * Fill in argument portion of vector table. 796 */ 797 for (; argc > 0; --argc) { 798 suword(vectp++, (long)(intptr_t)destp); 799 while (*stringp++ != 0) 800 destp++; 801 destp++; 802 } 803 804 /* a null vector table pointer seperates the argp's from the envp's */ 805 suword(vectp++, 0); 806 807 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 808 suword(&arginfo->ps_nenvstr, envc); 809 810 /* 811 * Fill in environment portion of vector table. 812 */ 813 for (; envc > 0; --envc) { 814 suword(vectp++, (long)(intptr_t)destp); 815 while (*stringp++ != 0) 816 destp++; 817 destp++; 818 } 819 820 /* end of vector table is a null pointer */ 821 suword(vectp, 0); 822 823 return (stack_base); 824 } 825 826 /* 827 * Check permissions of file to execute. 828 * Return 0 for success or error code on failure. 829 */ 830 int 831 exec_check_permissions(imgp) 832 struct image_params *imgp; 833 { 834 struct proc *p = imgp->proc; 835 struct vnode *vp = imgp->vp; 836 struct vattr *attr = imgp->attr; 837 struct thread *td = p->p_thread; 838 int error; 839 840 /* Get file attributes */ 841 error = VOP_GETATTR(vp, attr, td); 842 if (error) 843 return (error); 844 845 /* 846 * 1) Check if file execution is disabled for the filesystem that this 847 * file resides on. 848 * 2) Insure that at least one execute bit is on - otherwise root 849 * will always succeed, and we don't want to happen unless the 850 * file really is executable. 851 * 3) Insure that the file is a regular file. 852 */ 853 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 854 ((attr->va_mode & 0111) == 0) || 855 (attr->va_type != VREG)) { 856 return (EACCES); 857 } 858 859 /* 860 * Zero length files can't be exec'd 861 */ 862 if (attr->va_size == 0) 863 return (ENOEXEC); 864 865 /* 866 * Check for execute permission to file based on current credentials. 867 */ 868 error = VOP_ACCESS(vp, VEXEC, p->p_ucred, td); 869 if (error) 870 return (error); 871 872 /* 873 * Check number of open-for-writes on the file and deny execution 874 * if there are any. 875 */ 876 if (vp->v_writecount) 877 return (ETXTBSY); 878 879 /* 880 * Call filesystem specific open routine (which does nothing in the 881 * general case). 882 */ 883 error = VOP_OPEN(vp, FREAD, p->p_ucred, td); 884 if (error) 885 return (error); 886 887 return (0); 888 } 889 890 /* 891 * Exec handler registration 892 */ 893 int 894 exec_register(execsw_arg) 895 const struct execsw *execsw_arg; 896 { 897 const struct execsw **es, **xs, **newexecsw; 898 int count = 2; /* New slot and trailing NULL */ 899 900 if (execsw) 901 for (es = execsw; *es; es++) 902 count++; 903 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 904 if (newexecsw == NULL) 905 return ENOMEM; 906 xs = newexecsw; 907 if (execsw) 908 for (es = execsw; *es; es++) 909 *xs++ = *es; 910 *xs++ = execsw_arg; 911 *xs = NULL; 912 if (execsw) 913 free(execsw, M_TEMP); 914 execsw = newexecsw; 915 return 0; 916 } 917 918 int 919 exec_unregister(execsw_arg) 920 const struct execsw *execsw_arg; 921 { 922 const struct execsw **es, **xs, **newexecsw; 923 int count = 1; 924 925 if (execsw == NULL) 926 panic("unregister with no handlers left?\n"); 927 928 for (es = execsw; *es; es++) { 929 if (*es == execsw_arg) 930 break; 931 } 932 if (*es == NULL) 933 return ENOENT; 934 for (es = execsw; *es; es++) 935 if (*es != execsw_arg) 936 count++; 937 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 938 if (newexecsw == NULL) 939 return ENOMEM; 940 xs = newexecsw; 941 for (es = execsw; *es; es++) 942 if (*es != execsw_arg) 943 *xs++ = *es; 944 *xs = NULL; 945 if (execsw) 946 free(execsw, M_TEMP); 947 execsw = newexecsw; 948 return 0; 949 } 950