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 1.11 2003/08/26 21:09:02 rob 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/wait.h> 42 #include <sys/malloc.h> 43 #include <sys/proc.h> 44 #include <sys/signalvar.h> 45 #include <sys/pioctl.h> 46 #include <sys/namei.h> 47 #include <sys/sysent.h> 48 #include <sys/shm.h> 49 #include <sys/sysctl.h> 50 #include <sys/vnode.h> 51 #include <sys/aio.h> 52 53 #include <vm/vm.h> 54 #include <vm/vm_param.h> 55 #include <sys/lock.h> 56 #include <vm/pmap.h> 57 #include <vm/vm_page.h> 58 #include <vm/vm_map.h> 59 #include <vm/vm_kern.h> 60 #include <vm/vm_extern.h> 61 #include <vm/vm_object.h> 62 #include <vm/vm_pager.h> 63 64 #include <sys/user.h> 65 #include <machine/reg.h> 66 67 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 68 69 static register_t *exec_copyout_strings (struct image_params *); 70 71 /* XXX This should be vm_size_t. */ 72 static u_long ps_strings = PS_STRINGS; 73 SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, ""); 74 75 /* XXX This should be vm_size_t. */ 76 static u_long usrstack = USRSTACK; 77 SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, ""); 78 79 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 80 SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 81 &ps_arg_cache_limit, 0, ""); 82 83 int ps_argsopen = 1; 84 SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, ""); 85 86 /* 87 * Each of the items is a pointer to a `const struct execsw', hence the 88 * double pointer here. 89 */ 90 static const struct execsw **execsw; 91 92 /* 93 * execve() system call. 94 */ 95 int 96 execve(struct execve_args *uap) 97 { 98 struct thread *td = curthread; 99 struct proc *p = td->td_proc; 100 struct nameidata nd, *ndp; 101 register_t *stack_base; 102 int error, len, i; 103 struct image_params image_params, *imgp; 104 struct vattr attr; 105 int (*img_first) (struct image_params *); 106 107 KKASSERT(p); 108 imgp = &image_params; 109 110 /* 111 * Lock the process and set the P_INEXEC flag to indicate that 112 * it should be left alone until we're done here. This is 113 * necessary to avoid race conditions - e.g. in ptrace() - 114 * that might allow a local user to illicitly obtain elevated 115 * privileges. 116 */ 117 p->p_flag |= P_INEXEC; 118 119 /* 120 * Initialize part of the common data 121 */ 122 imgp->proc = p; 123 imgp->uap = uap; 124 imgp->attr = &attr; 125 imgp->argc = imgp->envc = 0; 126 imgp->argv0 = NULL; 127 imgp->entry_addr = 0; 128 imgp->vmspace_destroyed = 0; 129 imgp->interpreted = 0; 130 imgp->interpreter_name[0] = '\0'; 131 imgp->auxargs = NULL; 132 imgp->vp = NULL; 133 imgp->firstpage = NULL; 134 imgp->ps_strings = 0; 135 136 /* 137 * Allocate temporary demand zeroed space for argument and 138 * environment strings 139 */ 140 imgp->stringbase = (char *)kmem_alloc_wait(exec_map, ARG_MAX + PAGE_SIZE); 141 if (imgp->stringbase == NULL) { 142 error = ENOMEM; 143 goto exec_fail; 144 } 145 imgp->stringp = imgp->stringbase; 146 imgp->stringspace = ARG_MAX; 147 imgp->image_header = imgp->stringbase + ARG_MAX; 148 149 /* 150 * Translate the file name. namei() returns a vnode pointer 151 * in ni_vp amoung other things. 152 */ 153 ndp = &nd; 154 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 155 UIO_USERSPACE, uap->fname, td); 156 157 interpret: 158 159 error = namei(ndp); 160 if (error) { 161 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase, 162 ARG_MAX + PAGE_SIZE); 163 goto exec_fail; 164 } 165 166 imgp->vp = ndp->ni_vp; 167 imgp->fname = uap->fname; 168 169 /* 170 * Check file permissions (also 'opens' file) 171 */ 172 error = exec_check_permissions(imgp); 173 if (error) { 174 VOP_UNLOCK(imgp->vp, 0, td); 175 goto exec_fail_dealloc; 176 } 177 178 error = exec_map_first_page(imgp); 179 VOP_UNLOCK(imgp->vp, 0, td); 180 if (error) 181 goto exec_fail_dealloc; 182 183 /* 184 * If the current process has a special image activator it 185 * wants to try first, call it. For example, emulating shell 186 * scripts differently. 187 */ 188 error = -1; 189 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 190 error = img_first(imgp); 191 192 /* 193 * Loop through the list of image activators, calling each one. 194 * An activator returns -1 if there is no match, 0 on success, 195 * and an error otherwise. 196 */ 197 for (i = 0; error == -1 && execsw[i]; ++i) { 198 if (execsw[i]->ex_imgact == NULL || 199 execsw[i]->ex_imgact == img_first) { 200 continue; 201 } 202 error = (*execsw[i]->ex_imgact)(imgp); 203 } 204 205 if (error) { 206 if (error == -1) 207 error = ENOEXEC; 208 goto exec_fail_dealloc; 209 } 210 211 /* 212 * Special interpreter operation, cleanup and loop up to try to 213 * activate the interpreter. 214 */ 215 if (imgp->interpreted) { 216 exec_unmap_first_page(imgp); 217 /* free name buffer and old vnode */ 218 NDFREE(ndp, NDF_ONLY_PNBUF); 219 vrele(ndp->ni_vp); 220 /* set new name to that of the interpreter */ 221 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 222 UIO_SYSSPACE, imgp->interpreter_name, td); 223 goto interpret; 224 } 225 226 /* 227 * Copy out strings (args and env) and initialize stack base 228 */ 229 stack_base = exec_copyout_strings(imgp); 230 p->p_vmspace->vm_minsaddr = (char *)stack_base; 231 232 /* 233 * If custom stack fixup routine present for this process 234 * let it do the stack setup. 235 * Else stuff argument count as first item on stack 236 */ 237 if (p->p_sysent->sv_fixup) 238 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 239 else 240 suword(--stack_base, imgp->argc); 241 242 /* 243 * For security and other reasons, the file descriptor table cannot 244 * be shared after an exec. 245 */ 246 if (p->p_fd->fd_refcnt > 1) { 247 struct filedesc *tmp; 248 249 tmp = fdcopy(p); 250 fdfree(p); 251 p->p_fd = tmp; 252 } 253 254 /* 255 * For security and other reasons, signal handlers cannot 256 * be shared after an exec. The new proces gets a copy of the old 257 * handlers. In execsigs(), the new process will have its signals 258 * reset. 259 */ 260 if (p->p_procsig->ps_refcnt > 1) { 261 struct procsig *newprocsig; 262 263 MALLOC(newprocsig, struct procsig *, sizeof(struct procsig), 264 M_SUBPROC, M_WAITOK); 265 bcopy(p->p_procsig, newprocsig, sizeof(*newprocsig)); 266 p->p_procsig->ps_refcnt--; 267 p->p_procsig = newprocsig; 268 p->p_procsig->ps_refcnt = 1; 269 if (p->p_sigacts == &p->p_addr->u_sigacts) 270 panic("shared procsig but private sigacts?"); 271 272 p->p_addr->u_sigacts = *p->p_sigacts; 273 p->p_sigacts = &p->p_addr->u_sigacts; 274 } 275 276 /* Stop profiling */ 277 stopprofclock(p); 278 279 /* close files on exec */ 280 fdcloseexec(p); 281 282 /* reset caught signals */ 283 execsigs(p); 284 285 /* name this process - nameiexec(p, ndp) */ 286 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 287 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 288 p->p_comm[len] = 0; 289 290 /* 291 * mark as execed, wakeup the process that vforked (if any) and tell 292 * it that it now has its own resources back 293 */ 294 p->p_flag |= P_EXEC; 295 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 296 p->p_flag &= ~P_PPWAIT; 297 wakeup((caddr_t)p->p_pptr); 298 } 299 300 /* 301 * Implement image setuid/setgid. 302 * 303 * Don't honor setuid/setgid if the filesystem prohibits it or if 304 * the process is being traced. 305 */ 306 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 307 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 308 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 309 (p->p_flag & P_TRACED) == 0) { 310 /* 311 * Turn off syscall tracing for set-id programs, except for 312 * root. Record any set-id flags first to make sure that 313 * we do not regain any tracing during a possible block. 314 */ 315 setsugid(); 316 if (p->p_tracep && suser(td)) { 317 struct vnode *vtmp; 318 319 if ((vtmp = p->p_tracep) != NULL) { 320 p->p_tracep = NULL; 321 p->p_traceflag = 0; 322 vrele(vtmp); 323 } 324 } 325 /* Close any file descriptors 0..2 that reference procfs */ 326 setugidsafety(p); 327 /* Make sure file descriptors 0..2 are in use. */ 328 error = fdcheckstd(p); 329 if (error != 0) 330 goto exec_fail_dealloc; 331 /* 332 * Set the new credentials. 333 */ 334 cratom(&p->p_ucred); 335 if (attr.va_mode & VSUID) 336 change_euid(attr.va_uid); 337 if (attr.va_mode & VSGID) 338 p->p_ucred->cr_gid = attr.va_gid; 339 } else { 340 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && 341 p->p_ucred->cr_gid == p->p_ucred->cr_rgid) 342 p->p_flag &= ~P_SUGID; 343 } 344 345 /* 346 * Implement correct POSIX saved-id behavior. 347 */ 348 if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || 349 p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { 350 cratom(&p->p_ucred); 351 p->p_ucred->cr_svuid = p->p_ucred->cr_uid; 352 p->p_ucred->cr_svgid = p->p_ucred->cr_gid; 353 } 354 355 /* 356 * Store the vp for use in procfs 357 */ 358 if (p->p_textvp) /* release old reference */ 359 vrele(p->p_textvp); 360 VREF(ndp->ni_vp); 361 p->p_textvp = ndp->ni_vp; 362 363 /* 364 * Notify others that we exec'd, and clear the P_INEXEC flag 365 * as we're now a bona fide freshly-execed process. 366 */ 367 KNOTE(&p->p_klist, NOTE_EXEC); 368 p->p_flag &= ~P_INEXEC; 369 370 /* 371 * If tracing the process, trap to debugger so breakpoints 372 * can be set before the program executes. 373 */ 374 STOPEVENT(p, S_EXEC, 0); 375 376 if (p->p_flag & P_TRACED) 377 psignal(p, SIGTRAP); 378 379 /* clear "fork but no exec" flag, as we _are_ execing */ 380 p->p_acflag &= ~AFORK; 381 382 /* Set values passed into the program in registers. */ 383 setregs(p, imgp->entry_addr, (u_long)(uintptr_t)stack_base, 384 imgp->ps_strings); 385 386 /* 387 * The syscall result is returned in registers to the new program. 388 * Linux will register %edx as an atexit function and we must be 389 * sure to set it to 0. XXX 390 */ 391 uap->sysmsg_result64 = 0; 392 393 /* Free any previous argument cache */ 394 if (p->p_args && --p->p_args->ar_ref == 0) 395 FREE(p->p_args, M_PARGS); 396 p->p_args = NULL; 397 398 /* Cache arguments if they fit inside our allowance */ 399 i = imgp->endargs - imgp->stringbase; 400 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 401 MALLOC(p->p_args, struct pargs *, sizeof(struct pargs) + i, 402 M_PARGS, M_WAITOK); 403 p->p_args->ar_ref = 1; 404 p->p_args->ar_length = i; 405 bcopy(imgp->stringbase, p->p_args->ar_args, i); 406 } 407 408 exec_fail_dealloc: 409 410 /* 411 * free various allocated resources 412 */ 413 if (imgp->firstpage) 414 exec_unmap_first_page(imgp); 415 416 if (imgp->stringbase != NULL) 417 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase, 418 ARG_MAX + PAGE_SIZE); 419 420 if (imgp->vp) { 421 NDFREE(ndp, NDF_ONLY_PNBUF); 422 vrele(imgp->vp); 423 } 424 425 if (error == 0) 426 return (0); 427 428 exec_fail: 429 /* we're done here, clear P_INEXEC */ 430 p->p_flag &= ~P_INEXEC; 431 if (imgp->vmspace_destroyed) { 432 /* sorry, no more process anymore. exit gracefully */ 433 exit1(W_EXITCODE(0, SIGABRT)); 434 /* NOT REACHED */ 435 return(0); 436 } else { 437 return(error); 438 } 439 } 440 441 int 442 exec_map_first_page(struct image_params *imgp) 443 { 444 int s, rv, i; 445 int initial_pagein; 446 vm_page_t ma[VM_INITIAL_PAGEIN]; 447 vm_object_t object; 448 449 450 if (imgp->firstpage) { 451 exec_unmap_first_page(imgp); 452 } 453 454 VOP_GETVOBJECT(imgp->vp, &object); 455 s = splvm(); 456 457 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 458 459 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 460 initial_pagein = VM_INITIAL_PAGEIN; 461 if (initial_pagein > object->size) 462 initial_pagein = object->size; 463 for (i = 1; i < initial_pagein; i++) { 464 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 465 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy) 466 break; 467 if (ma[i]->valid) 468 break; 469 vm_page_busy(ma[i]); 470 } else { 471 ma[i] = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 472 if (ma[i] == NULL) 473 break; 474 } 475 } 476 initial_pagein = i; 477 478 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 479 ma[0] = vm_page_lookup(object, 0); 480 481 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || (ma[0]->valid == 0)) { 482 if (ma[0]) { 483 vm_page_protect(ma[0], VM_PROT_NONE); 484 vm_page_free(ma[0]); 485 } 486 splx(s); 487 return EIO; 488 } 489 } 490 491 vm_page_wire(ma[0]); 492 vm_page_wakeup(ma[0]); 493 splx(s); 494 495 pmap_kenter((vm_offset_t) imgp->image_header, VM_PAGE_TO_PHYS(ma[0])); 496 imgp->firstpage = ma[0]; 497 498 return 0; 499 } 500 501 void 502 exec_unmap_first_page(imgp) 503 struct image_params *imgp; 504 { 505 if (imgp->firstpage) { 506 pmap_kremove((vm_offset_t) imgp->image_header); 507 vm_page_unwire(imgp->firstpage, 1); 508 imgp->firstpage = NULL; 509 } 510 } 511 512 /* 513 * Destroy old address space, and allocate a new stack 514 * The new stack is only SGROWSIZ large because it is grown 515 * automatically in trap.c. 516 */ 517 int 518 exec_new_vmspace(imgp) 519 struct image_params *imgp; 520 { 521 int error; 522 struct vmspace *vmspace = imgp->proc->p_vmspace; 523 vm_offset_t stack_addr = USRSTACK - maxssiz; 524 vm_map_t map = &vmspace->vm_map; 525 526 imgp->vmspace_destroyed = 1; 527 528 /* 529 * Prevent a pending AIO from modifying the new address space. 530 */ 531 aio_proc_rundown(imgp->proc); 532 533 /* 534 * Blow away entire process VM, if address space not shared, 535 * otherwise, create a new VM space so that other threads are 536 * not disrupted 537 */ 538 if (vmspace->vm_refcnt == 1) { 539 shmexit(vmspace); 540 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); 541 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); 542 } else { 543 vmspace_exec(imgp->proc); 544 vmspace = imgp->proc->p_vmspace; 545 map = &vmspace->vm_map; 546 } 547 548 /* Allocate a new stack */ 549 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 550 VM_PROT_ALL, VM_PROT_ALL, 0); 551 if (error) 552 return (error); 553 554 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 555 * VM_STACK case, but they are still used to monitor the size of the 556 * process stack so we can check the stack rlimit. 557 */ 558 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 559 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 560 561 return(0); 562 } 563 564 /* 565 * Copy out argument and environment strings from the old process 566 * address space into the temporary string buffer. 567 */ 568 int 569 exec_extract_strings(imgp) 570 struct image_params *imgp; 571 { 572 char **argv, **envv; 573 char *argp, *envp; 574 int error; 575 size_t length; 576 577 /* 578 * extract arguments first 579 */ 580 581 argv = imgp->uap->argv; 582 583 if (argv) { 584 argp = (caddr_t) (intptr_t) fuword(argv); 585 if (argp == (caddr_t) -1) 586 return (EFAULT); 587 if (argp) 588 argv++; 589 if (imgp->argv0) 590 argp = imgp->argv0; 591 if (argp) { 592 do { 593 if (argp == (caddr_t) -1) 594 return (EFAULT); 595 if ((error = copyinstr(argp, imgp->stringp, 596 imgp->stringspace, &length))) { 597 if (error == ENAMETOOLONG) 598 return(E2BIG); 599 return (error); 600 } 601 imgp->stringspace -= length; 602 imgp->stringp += length; 603 imgp->argc++; 604 } while ((argp = (caddr_t) (intptr_t) fuword(argv++))); 605 } 606 } 607 608 imgp->endargs = imgp->stringp; 609 610 /* 611 * extract environment strings 612 */ 613 614 envv = imgp->uap->envv; 615 616 if (envv) { 617 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 618 if (envp == (caddr_t) -1) 619 return (EFAULT); 620 if ((error = copyinstr(envp, imgp->stringp, 621 imgp->stringspace, &length))) { 622 if (error == ENAMETOOLONG) 623 return(E2BIG); 624 return (error); 625 } 626 imgp->stringspace -= length; 627 imgp->stringp += length; 628 imgp->envc++; 629 } 630 } 631 632 return (0); 633 } 634 635 /* 636 * Copy strings out to the new process address space, constructing 637 * new arg and env vector tables. Return a pointer to the base 638 * so that it can be used as the initial stack pointer. 639 */ 640 register_t * 641 exec_copyout_strings(imgp) 642 struct image_params *imgp; 643 { 644 int argc, envc; 645 char **vectp; 646 char *stringp, *destp; 647 register_t *stack_base; 648 struct ps_strings *arginfo; 649 int szsigcode; 650 651 /* 652 * Calculate string base and vector table pointers. 653 * Also deal with signal trampoline code for this exec type. 654 */ 655 arginfo = (struct ps_strings *)PS_STRINGS; 656 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 657 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 658 roundup((ARG_MAX - imgp->stringspace), sizeof(char *)); 659 660 /* 661 * install sigcode 662 */ 663 if (szsigcode) 664 copyout(imgp->proc->p_sysent->sv_sigcode, 665 ((caddr_t)arginfo - szsigcode), szsigcode); 666 667 /* 668 * If we have a valid auxargs ptr, prepare some room 669 * on the stack. 670 */ 671 if (imgp->auxargs) 672 /* 673 * The '+ 2' is for the null pointers at the end of each of the 674 * arg and env vector sets, and 'AT_COUNT*2' is room for the 675 * ELF Auxargs data. 676 */ 677 vectp = (char **)(destp - (imgp->argc + imgp->envc + 2 + 678 AT_COUNT*2) * sizeof(char*)); 679 else 680 /* 681 * The '+ 2' is for the null pointers at the end of each of the 682 * arg and env vector sets 683 */ 684 vectp = (char **) 685 (destp - (imgp->argc + imgp->envc + 2) * sizeof(char*)); 686 687 /* 688 * vectp also becomes our initial stack base 689 */ 690 stack_base = (register_t *)vectp; 691 692 stringp = imgp->stringbase; 693 argc = imgp->argc; 694 envc = imgp->envc; 695 696 /* 697 * Copy out strings - arguments and environment. 698 */ 699 copyout(stringp, destp, ARG_MAX - imgp->stringspace); 700 701 /* 702 * Fill in "ps_strings" struct for ps, w, etc. 703 */ 704 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 705 suword(&arginfo->ps_nargvstr, argc); 706 707 /* 708 * Fill in argument portion of vector table. 709 */ 710 for (; argc > 0; --argc) { 711 suword(vectp++, (long)(intptr_t)destp); 712 while (*stringp++ != 0) 713 destp++; 714 destp++; 715 } 716 717 /* a null vector table pointer seperates the argp's from the envp's */ 718 suword(vectp++, 0); 719 720 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 721 suword(&arginfo->ps_nenvstr, envc); 722 723 /* 724 * Fill in environment portion of vector table. 725 */ 726 for (; envc > 0; --envc) { 727 suword(vectp++, (long)(intptr_t)destp); 728 while (*stringp++ != 0) 729 destp++; 730 destp++; 731 } 732 733 /* end of vector table is a null pointer */ 734 suword(vectp, 0); 735 736 return (stack_base); 737 } 738 739 /* 740 * Check permissions of file to execute. 741 * Return 0 for success or error code on failure. 742 */ 743 int 744 exec_check_permissions(imgp) 745 struct image_params *imgp; 746 { 747 struct proc *p = imgp->proc; 748 struct vnode *vp = imgp->vp; 749 struct vattr *attr = imgp->attr; 750 struct thread *td = p->p_thread; 751 int error; 752 753 /* Get file attributes */ 754 error = VOP_GETATTR(vp, attr, td); 755 if (error) 756 return (error); 757 758 /* 759 * 1) Check if file execution is disabled for the filesystem that this 760 * file resides on. 761 * 2) Insure that at least one execute bit is on - otherwise root 762 * will always succeed, and we don't want to happen unless the 763 * file really is executable. 764 * 3) Insure that the file is a regular file. 765 */ 766 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 767 ((attr->va_mode & 0111) == 0) || 768 (attr->va_type != VREG)) { 769 return (EACCES); 770 } 771 772 /* 773 * Zero length files can't be exec'd 774 */ 775 if (attr->va_size == 0) 776 return (ENOEXEC); 777 778 /* 779 * Check for execute permission to file based on current credentials. 780 */ 781 error = VOP_ACCESS(vp, VEXEC, p->p_ucred, td); 782 if (error) 783 return (error); 784 785 /* 786 * Check number of open-for-writes on the file and deny execution 787 * if there are any. 788 */ 789 if (vp->v_writecount) 790 return (ETXTBSY); 791 792 /* 793 * Call filesystem specific open routine (which does nothing in the 794 * general case). 795 */ 796 error = VOP_OPEN(vp, FREAD, p->p_ucred, td); 797 if (error) 798 return (error); 799 800 return (0); 801 } 802 803 /* 804 * Exec handler registration 805 */ 806 int 807 exec_register(execsw_arg) 808 const struct execsw *execsw_arg; 809 { 810 const struct execsw **es, **xs, **newexecsw; 811 int count = 2; /* New slot and trailing NULL */ 812 813 if (execsw) 814 for (es = execsw; *es; es++) 815 count++; 816 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 817 if (newexecsw == NULL) 818 return ENOMEM; 819 xs = newexecsw; 820 if (execsw) 821 for (es = execsw; *es; es++) 822 *xs++ = *es; 823 *xs++ = execsw_arg; 824 *xs = NULL; 825 if (execsw) 826 free(execsw, M_TEMP); 827 execsw = newexecsw; 828 return 0; 829 } 830 831 int 832 exec_unregister(execsw_arg) 833 const struct execsw *execsw_arg; 834 { 835 const struct execsw **es, **xs, **newexecsw; 836 int count = 1; 837 838 if (execsw == NULL) 839 panic("unregister with no handlers left?\n"); 840 841 for (es = execsw; *es; es++) { 842 if (*es == execsw_arg) 843 break; 844 } 845 if (*es == NULL) 846 return ENOENT; 847 for (es = execsw; *es; es++) 848 if (*es != execsw_arg) 849 count++; 850 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 851 if (newexecsw == NULL) 852 return ENOMEM; 853 xs = newexecsw; 854 for (es = execsw; *es; es++) 855 if (*es != execsw_arg) 856 *xs++ = *es; 857 *xs = NULL; 858 if (execsw) 859 free(execsw, M_TEMP); 860 execsw = newexecsw; 861 return 0; 862 } 863