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 1.14 2003/11/12 01:00:33 daver 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->auxargs = NULL; 153 imgp->vp = NULL; 154 imgp->firstpage = NULL; 155 imgp->ps_strings = 0; 156 157 /* 158 * Allocate temporary demand zeroed space for argument and 159 * environment strings 160 */ 161 imgp->image_header = (char *)kmem_alloc_wait(exec_map, PAGE_SIZE); 162 if (imgp->image_header == NULL) { 163 error = ENOMEM; 164 goto exec_fail; 165 } 166 167 interpret: 168 169 /* 170 * Translate the file name. namei() returns a vnode pointer 171 * in ni_vp amoung other things. 172 */ 173 error = namei(ndp); 174 if (error) { 175 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->image_header, 176 PAGE_SIZE); 177 goto exec_fail; 178 } 179 180 imgp->vp = ndp->ni_vp; 181 182 /* 183 * Check file permissions (also 'opens' file) 184 */ 185 error = exec_check_permissions(imgp); 186 if (error) { 187 VOP_UNLOCK(imgp->vp, 0, td); 188 goto exec_fail_dealloc; 189 } 190 191 error = exec_map_first_page(imgp); 192 VOP_UNLOCK(imgp->vp, 0, td); 193 if (error) 194 goto exec_fail_dealloc; 195 196 if (debug_execve_args && imgp->interpreted) { 197 printf(" target is interpreted -- recursive pass\n"); 198 printf(" interpreter: %s\n", imgp->interpreter_name); 199 print_execve_args(args); 200 } 201 202 /* 203 * If the current process has a special image activator it 204 * wants to try first, call it. For example, emulating shell 205 * scripts differently. 206 */ 207 error = -1; 208 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 209 error = img_first(imgp); 210 211 /* 212 * Loop through the list of image activators, calling each one. 213 * An activator returns -1 if there is no match, 0 on success, 214 * and an error otherwise. 215 */ 216 for (i = 0; error == -1 && execsw[i]; ++i) { 217 if (execsw[i]->ex_imgact == NULL || 218 execsw[i]->ex_imgact == img_first) { 219 continue; 220 } 221 error = (*execsw[i]->ex_imgact)(imgp); 222 } 223 224 if (error) { 225 if (error == -1) 226 error = ENOEXEC; 227 goto exec_fail_dealloc; 228 } 229 230 /* 231 * Special interpreter operation, cleanup and loop up to try to 232 * activate the interpreter. 233 */ 234 if (imgp->interpreted) { 235 exec_unmap_first_page(imgp); 236 /* free name buffer and old vnode */ 237 NDFREE(ndp, NDF_ONLY_PNBUF); 238 vrele(ndp->ni_vp); 239 /* set new name to that of the interpreter */ 240 NDINIT(ndp, NAMEI_LOOKUP, 241 CNP_LOCKLEAF | CNP_FOLLOW | CNP_SAVENAME, 242 UIO_SYSSPACE, imgp->interpreter_name, td); 243 goto interpret; 244 } 245 246 /* 247 * Copy out strings (args and env) and initialize stack base 248 */ 249 stack_base = exec_copyout_strings(imgp); 250 p->p_vmspace->vm_minsaddr = (char *)stack_base; 251 252 /* 253 * If custom stack fixup routine present for this process 254 * let it do the stack setup. 255 * Else stuff argument count as first item on stack 256 */ 257 if (p->p_sysent->sv_fixup) 258 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 259 else 260 suword(--stack_base, imgp->args->argc); 261 262 /* 263 * For security and other reasons, the file descriptor table cannot 264 * be shared after an exec. 265 */ 266 if (p->p_fd->fd_refcnt > 1) { 267 struct filedesc *tmp; 268 269 tmp = fdcopy(p); 270 fdfree(p); 271 p->p_fd = tmp; 272 } 273 274 /* 275 * For security and other reasons, signal handlers cannot 276 * be shared after an exec. The new proces gets a copy of the old 277 * handlers. In execsigs(), the new process will have its signals 278 * reset. 279 */ 280 if (p->p_procsig->ps_refcnt > 1) { 281 struct procsig *newprocsig; 282 283 MALLOC(newprocsig, struct procsig *, sizeof(struct procsig), 284 M_SUBPROC, M_WAITOK); 285 bcopy(p->p_procsig, newprocsig, sizeof(*newprocsig)); 286 p->p_procsig->ps_refcnt--; 287 p->p_procsig = newprocsig; 288 p->p_procsig->ps_refcnt = 1; 289 if (p->p_sigacts == &p->p_addr->u_sigacts) 290 panic("shared procsig but private sigacts?"); 291 292 p->p_addr->u_sigacts = *p->p_sigacts; 293 p->p_sigacts = &p->p_addr->u_sigacts; 294 } 295 296 /* Stop profiling */ 297 stopprofclock(p); 298 299 /* close files on exec */ 300 fdcloseexec(p); 301 302 /* reset caught signals */ 303 execsigs(p); 304 305 /* name this process - nameiexec(p, ndp) */ 306 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 307 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 308 p->p_comm[len] = 0; 309 310 /* 311 * mark as execed, wakeup the process that vforked (if any) and tell 312 * it that it now has its own resources back 313 */ 314 p->p_flag |= P_EXEC; 315 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 316 p->p_flag &= ~P_PPWAIT; 317 wakeup((caddr_t)p->p_pptr); 318 } 319 320 /* 321 * Implement image setuid/setgid. 322 * 323 * Don't honor setuid/setgid if the filesystem prohibits it or if 324 * the process is being traced. 325 */ 326 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 327 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 328 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 329 (p->p_flag & P_TRACED) == 0) { 330 /* 331 * Turn off syscall tracing for set-id programs, except for 332 * root. Record any set-id flags first to make sure that 333 * we do not regain any tracing during a possible block. 334 */ 335 setsugid(); 336 if (p->p_tracep && suser(td)) { 337 struct vnode *vtmp; 338 339 if ((vtmp = p->p_tracep) != NULL) { 340 p->p_tracep = NULL; 341 p->p_traceflag = 0; 342 vrele(vtmp); 343 } 344 } 345 /* Close any file descriptors 0..2 that reference procfs */ 346 setugidsafety(p); 347 /* Make sure file descriptors 0..2 are in use. */ 348 error = fdcheckstd(p); 349 if (error != 0) 350 goto exec_fail_dealloc; 351 /* 352 * Set the new credentials. 353 */ 354 cratom(&p->p_ucred); 355 if (attr.va_mode & VSUID) 356 change_euid(attr.va_uid); 357 if (attr.va_mode & VSGID) 358 p->p_ucred->cr_gid = attr.va_gid; 359 360 /* 361 * Clear local varsym variables 362 */ 363 varsymset_clean(&p->p_varsymset); 364 } else { 365 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && 366 p->p_ucred->cr_gid == p->p_ucred->cr_rgid) 367 p->p_flag &= ~P_SUGID; 368 } 369 370 /* 371 * Implement correct POSIX saved-id behavior. 372 */ 373 if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || 374 p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { 375 cratom(&p->p_ucred); 376 p->p_ucred->cr_svuid = p->p_ucred->cr_uid; 377 p->p_ucred->cr_svgid = p->p_ucred->cr_gid; 378 } 379 380 /* 381 * Store the vp for use in procfs 382 */ 383 if (p->p_textvp) /* release old reference */ 384 vrele(p->p_textvp); 385 VREF(ndp->ni_vp); 386 p->p_textvp = ndp->ni_vp; 387 388 /* 389 * Notify others that we exec'd, and clear the P_INEXEC flag 390 * as we're now a bona fide freshly-execed process. 391 */ 392 KNOTE(&p->p_klist, NOTE_EXEC); 393 p->p_flag &= ~P_INEXEC; 394 395 /* 396 * If tracing the process, trap to debugger so breakpoints 397 * can be set before the program executes. 398 */ 399 STOPEVENT(p, S_EXEC, 0); 400 401 if (p->p_flag & P_TRACED) 402 psignal(p, SIGTRAP); 403 404 /* clear "fork but no exec" flag, as we _are_ execing */ 405 p->p_acflag &= ~AFORK; 406 407 /* Set values passed into the program in registers. */ 408 setregs(p, imgp->entry_addr, (u_long)(uintptr_t)stack_base, 409 imgp->ps_strings); 410 411 /* Free any previous argument cache */ 412 if (p->p_args && --p->p_args->ar_ref == 0) 413 FREE(p->p_args, M_PARGS); 414 p->p_args = NULL; 415 416 /* Cache arguments if they fit inside our allowance */ 417 i = imgp->args->begin_envv - imgp->args->begin_argv; 418 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 419 MALLOC(p->p_args, struct pargs *, sizeof(struct pargs) + i, 420 M_PARGS, M_WAITOK); 421 p->p_args->ar_ref = 1; 422 p->p_args->ar_length = i; 423 bcopy(imgp->args->begin_argv, p->p_args->ar_args, i); 424 } 425 426 exec_fail_dealloc: 427 428 /* 429 * free various allocated resources 430 */ 431 if (imgp->firstpage) 432 exec_unmap_first_page(imgp); 433 434 if (imgp->image_header != NULL) 435 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->image_header, 436 PAGE_SIZE); 437 438 if (imgp->vp) { 439 NDFREE(ndp, NDF_ONLY_PNBUF); 440 vrele(imgp->vp); 441 } 442 443 if (error == 0) 444 return (0); 445 446 exec_fail: 447 /* we're done here, clear P_INEXEC */ 448 p->p_flag &= ~P_INEXEC; 449 if (imgp->vmspace_destroyed) { 450 /* sorry, no more process anymore. exit gracefully */ 451 exit1(W_EXITCODE(0, SIGABRT)); 452 /* NOT REACHED */ 453 return(0); 454 } else { 455 return(error); 456 } 457 } 458 459 /* 460 * execve() system call. 461 */ 462 int 463 execve(struct execve_args *uap) 464 { 465 struct thread *td = curthread; 466 struct nameidata nd; 467 struct image_args args; 468 int error; 469 470 NDINIT(&nd, NAMEI_LOOKUP, CNP_LOCKLEAF | CNP_FOLLOW | CNP_SAVENAME, 471 UIO_USERSPACE, uap->fname, td); 472 473 error = exec_copyin_args(&args, uap->fname, PATH_USERSPACE, 474 uap->argv, uap->envv); 475 if (error) 476 return (error); 477 478 error = kern_execve(&nd, &args); 479 480 exec_free_args(&args); 481 482 /* 483 * The syscall result is returned in registers to the new program. 484 * Linux will register %edx as an atexit function and we must be 485 * sure to set it to 0. XXX 486 */ 487 if (error == 0) 488 uap->sysmsg_result64 = 0; 489 490 return (error); 491 } 492 493 int 494 exec_map_first_page(struct image_params *imgp) 495 { 496 int s, rv, i; 497 int initial_pagein; 498 vm_page_t ma[VM_INITIAL_PAGEIN]; 499 vm_object_t object; 500 501 502 if (imgp->firstpage) { 503 exec_unmap_first_page(imgp); 504 } 505 506 VOP_GETVOBJECT(imgp->vp, &object); 507 s = splvm(); 508 509 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 510 511 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 512 initial_pagein = VM_INITIAL_PAGEIN; 513 if (initial_pagein > object->size) 514 initial_pagein = object->size; 515 for (i = 1; i < initial_pagein; i++) { 516 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 517 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy) 518 break; 519 if (ma[i]->valid) 520 break; 521 vm_page_busy(ma[i]); 522 } else { 523 ma[i] = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 524 if (ma[i] == NULL) 525 break; 526 } 527 } 528 initial_pagein = i; 529 530 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 531 ma[0] = vm_page_lookup(object, 0); 532 533 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || (ma[0]->valid == 0)) { 534 if (ma[0]) { 535 vm_page_protect(ma[0], VM_PROT_NONE); 536 vm_page_free(ma[0]); 537 } 538 splx(s); 539 return EIO; 540 } 541 } 542 543 vm_page_wire(ma[0]); 544 vm_page_wakeup(ma[0]); 545 splx(s); 546 547 pmap_kenter((vm_offset_t) imgp->image_header, VM_PAGE_TO_PHYS(ma[0])); 548 imgp->firstpage = ma[0]; 549 550 return 0; 551 } 552 553 void 554 exec_unmap_first_page(imgp) 555 struct image_params *imgp; 556 { 557 if (imgp->firstpage) { 558 pmap_kremove((vm_offset_t) imgp->image_header); 559 vm_page_unwire(imgp->firstpage, 1); 560 imgp->firstpage = NULL; 561 } 562 } 563 564 /* 565 * Destroy old address space, and allocate a new stack 566 * The new stack is only SGROWSIZ large because it is grown 567 * automatically in trap.c. 568 */ 569 int 570 exec_new_vmspace(imgp) 571 struct image_params *imgp; 572 { 573 int error; 574 struct vmspace *vmspace = imgp->proc->p_vmspace; 575 vm_offset_t stack_addr = USRSTACK - maxssiz; 576 vm_map_t map = &vmspace->vm_map; 577 578 imgp->vmspace_destroyed = 1; 579 580 /* 581 * Prevent a pending AIO from modifying the new address space. 582 */ 583 aio_proc_rundown(imgp->proc); 584 585 /* 586 * Blow away entire process VM, if address space not shared, 587 * otherwise, create a new VM space so that other threads are 588 * not disrupted 589 */ 590 if (vmspace->vm_refcnt == 1) { 591 shmexit(vmspace); 592 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); 593 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); 594 } else { 595 vmspace_exec(imgp->proc); 596 vmspace = imgp->proc->p_vmspace; 597 map = &vmspace->vm_map; 598 } 599 600 /* Allocate a new stack */ 601 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 602 VM_PROT_ALL, VM_PROT_ALL, 0); 603 if (error) 604 return (error); 605 606 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 607 * VM_STACK case, but they are still used to monitor the size of the 608 * process stack so we can check the stack rlimit. 609 */ 610 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 611 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 612 613 return(0); 614 } 615 616 /* 617 * Copy out argument and environment strings from the old process 618 * address space into the temporary string buffer. 619 */ 620 int 621 exec_copyin_args(struct image_args *args, char *fname, 622 enum exec_path_segflg segflg, char **argv, char **envv) 623 { 624 char *argp, *envp; 625 int error = 0; 626 size_t length; 627 628 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 args->argc = 0; 635 args->envc = 0; 636 637 args->fname = args->buf + ARG_MAX; 638 639 /* 640 * Copy the file name. 641 */ 642 if (segflg == PATH_SYSSPACE) { 643 error = copystr(fname, args->fname, PATH_MAX, &length); 644 } else if (segflg == PATH_USERSPACE) { 645 error = copyinstr(fname, args->fname, PATH_MAX, &length); 646 } 647 648 /* 649 * extract argument strings 650 */ 651 652 if (argv) { 653 argp = (caddr_t) (intptr_t) fuword(argv); 654 /* 655 * First argument is a special case. If it is a null 656 * string, we must copy the file name into the string 657 * buffer as the first argument. This guarantees that 658 * the interpreter knows what file to open in the case 659 * that we exec an interpreted file. 660 */ 661 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 662 if (argp == (caddr_t) -1) { 663 error = EFAULT; 664 goto cleanup; 665 } 666 error = copyinstr(argp, args->endp, 667 args->space, &length); 668 if (error == ENAMETOOLONG) 669 error = E2BIG; 670 if (error) 671 goto cleanup; 672 args->space -= length; 673 args->endp += length; 674 args->argc++; 675 } 676 } 677 678 args->begin_envv = args->endp; 679 680 /* 681 * extract environment strings 682 */ 683 684 if (envv) { 685 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 686 if (envp == (caddr_t) -1) { 687 error = EFAULT; 688 goto cleanup; 689 } 690 error = copyinstr(envp, args->endp, args->space, 691 &length); 692 if (error == ENAMETOOLONG) 693 error = E2BIG; 694 if (error) 695 goto cleanup; 696 args->space -= length; 697 args->endp += length; 698 args->envc++; 699 } 700 } 701 702 cleanup: 703 if (error) 704 exec_free_args(args); 705 return (error); 706 } 707 708 void 709 exec_free_args(struct image_args *args) 710 { 711 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf, PATH_MAX + ARG_MAX); 712 } 713 714 /* 715 * Copy strings out to the new process address space, constructing 716 * new arg and env vector tables. Return a pointer to the base 717 * so that it can be used as the initial stack pointer. 718 */ 719 register_t * 720 exec_copyout_strings(struct image_params *imgp) 721 { 722 int argc, envc; 723 char **vectp; 724 char *stringp, *destp; 725 register_t *stack_base; 726 struct ps_strings *arginfo; 727 int szsigcode; 728 729 /* 730 * Calculate string base and vector table pointers. 731 * Also deal with signal trampoline code for this exec type. 732 */ 733 arginfo = (struct ps_strings *)PS_STRINGS; 734 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 735 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 736 roundup((ARG_MAX - imgp->args->space), sizeof(char *)); 737 738 /* 739 * install sigcode 740 */ 741 if (szsigcode) 742 copyout(imgp->proc->p_sysent->sv_sigcode, 743 ((caddr_t)arginfo - szsigcode), szsigcode); 744 745 /* 746 * If we have a valid auxargs ptr, prepare some room 747 * on the stack. 748 */ 749 if (imgp->auxargs) 750 /* 751 * The '+ 2' is for the null pointers at the end of each of the 752 * arg and env vector sets, and 'AT_COUNT*2' is room for the 753 * ELF Auxargs data. 754 */ 755 vectp = (char **)(destp - (imgp->args->argc + 756 imgp->args->envc + 2 + AT_COUNT*2) * sizeof(char*)); 757 else 758 /* 759 * The '+ 2' is for the null pointers at the end of each of the 760 * arg and env vector sets 761 */ 762 vectp = (char **) 763 (destp - (imgp->args->argc + imgp->args->envc + 2) * 764 sizeof(char*)); 765 766 /* 767 * vectp also becomes our initial stack base 768 */ 769 stack_base = (register_t *)vectp; 770 771 stringp = imgp->args->begin_argv; 772 argc = imgp->args->argc; 773 envc = imgp->args->envc; 774 775 /* 776 * Copy out strings - arguments and environment. 777 */ 778 copyout(stringp, destp, ARG_MAX - imgp->args->space); 779 780 /* 781 * Fill in "ps_strings" struct for ps, w, etc. 782 */ 783 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 784 suword(&arginfo->ps_nargvstr, argc); 785 786 /* 787 * Fill in argument portion of vector table. 788 */ 789 for (; argc > 0; --argc) { 790 suword(vectp++, (long)(intptr_t)destp); 791 while (*stringp++ != 0) 792 destp++; 793 destp++; 794 } 795 796 /* a null vector table pointer seperates the argp's from the envp's */ 797 suword(vectp++, 0); 798 799 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 800 suword(&arginfo->ps_nenvstr, envc); 801 802 /* 803 * Fill in environment portion of vector table. 804 */ 805 for (; envc > 0; --envc) { 806 suword(vectp++, (long)(intptr_t)destp); 807 while (*stringp++ != 0) 808 destp++; 809 destp++; 810 } 811 812 /* end of vector table is a null pointer */ 813 suword(vectp, 0); 814 815 return (stack_base); 816 } 817 818 /* 819 * Check permissions of file to execute. 820 * Return 0 for success or error code on failure. 821 */ 822 int 823 exec_check_permissions(imgp) 824 struct image_params *imgp; 825 { 826 struct proc *p = imgp->proc; 827 struct vnode *vp = imgp->vp; 828 struct vattr *attr = imgp->attr; 829 struct thread *td = p->p_thread; 830 int error; 831 832 /* Get file attributes */ 833 error = VOP_GETATTR(vp, attr, td); 834 if (error) 835 return (error); 836 837 /* 838 * 1) Check if file execution is disabled for the filesystem that this 839 * file resides on. 840 * 2) Insure that at least one execute bit is on - otherwise root 841 * will always succeed, and we don't want to happen unless the 842 * file really is executable. 843 * 3) Insure that the file is a regular file. 844 */ 845 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 846 ((attr->va_mode & 0111) == 0) || 847 (attr->va_type != VREG)) { 848 return (EACCES); 849 } 850 851 /* 852 * Zero length files can't be exec'd 853 */ 854 if (attr->va_size == 0) 855 return (ENOEXEC); 856 857 /* 858 * Check for execute permission to file based on current credentials. 859 */ 860 error = VOP_ACCESS(vp, VEXEC, p->p_ucred, td); 861 if (error) 862 return (error); 863 864 /* 865 * Check number of open-for-writes on the file and deny execution 866 * if there are any. 867 */ 868 if (vp->v_writecount) 869 return (ETXTBSY); 870 871 /* 872 * Call filesystem specific open routine (which does nothing in the 873 * general case). 874 */ 875 error = VOP_OPEN(vp, FREAD, p->p_ucred, td); 876 if (error) 877 return (error); 878 879 return (0); 880 } 881 882 /* 883 * Exec handler registration 884 */ 885 int 886 exec_register(execsw_arg) 887 const struct execsw *execsw_arg; 888 { 889 const struct execsw **es, **xs, **newexecsw; 890 int count = 2; /* New slot and trailing NULL */ 891 892 if (execsw) 893 for (es = execsw; *es; es++) 894 count++; 895 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 896 if (newexecsw == NULL) 897 return ENOMEM; 898 xs = newexecsw; 899 if (execsw) 900 for (es = execsw; *es; es++) 901 *xs++ = *es; 902 *xs++ = execsw_arg; 903 *xs = NULL; 904 if (execsw) 905 free(execsw, M_TEMP); 906 execsw = newexecsw; 907 return 0; 908 } 909 910 int 911 exec_unregister(execsw_arg) 912 const struct execsw *execsw_arg; 913 { 914 const struct execsw **es, **xs, **newexecsw; 915 int count = 1; 916 917 if (execsw == NULL) 918 panic("unregister with no handlers left?\n"); 919 920 for (es = execsw; *es; es++) { 921 if (*es == execsw_arg) 922 break; 923 } 924 if (*es == NULL) 925 return ENOENT; 926 for (es = execsw; *es; es++) 927 if (*es != execsw_arg) 928 count++; 929 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 930 if (newexecsw == NULL) 931 return ENOMEM; 932 xs = newexecsw; 933 for (es = execsw; *es; es++) 934 if (*es != execsw_arg) 935 *xs++ = *es; 936 *xs = NULL; 937 if (execsw) 938 free(execsw, M_TEMP); 939 execsw = newexecsw; 940 return 0; 941 } 942