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 1.2 2003/06/17 04:28:41 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/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 __P((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 #ifndef _SYS_SYSPROTO_H_ 93 struct execve_args { 94 char *fname; 95 char **argv; 96 char **envv; 97 }; 98 #endif 99 100 /* 101 * execve() system call. 102 */ 103 int 104 execve(p, uap) 105 struct proc *p; 106 register struct execve_args *uap; 107 { 108 struct nameidata nd, *ndp; 109 register_t *stack_base; 110 int error, len, i; 111 struct image_params image_params, *imgp; 112 struct vattr attr; 113 int (*img_first) __P((struct image_params *)); 114 115 imgp = &image_params; 116 117 /* 118 * Lock the process and set the P_INEXEC flag to indicate that 119 * it should be left alone until we're done here. This is 120 * necessary to avoid race conditions - e.g. in ptrace() - 121 * that might allow a local user to illicitly obtain elevated 122 * privileges. 123 */ 124 p->p_flag |= P_INEXEC; 125 126 /* 127 * Initialize part of the common data 128 */ 129 imgp->proc = p; 130 imgp->uap = uap; 131 imgp->attr = &attr; 132 imgp->argc = imgp->envc = 0; 133 imgp->argv0 = NULL; 134 imgp->entry_addr = 0; 135 imgp->vmspace_destroyed = 0; 136 imgp->interpreted = 0; 137 imgp->interpreter_name[0] = '\0'; 138 imgp->auxargs = NULL; 139 imgp->vp = NULL; 140 imgp->firstpage = NULL; 141 imgp->ps_strings = 0; 142 143 /* 144 * Allocate temporary demand zeroed space for argument and 145 * environment strings 146 */ 147 imgp->stringbase = (char *)kmem_alloc_wait(exec_map, ARG_MAX + PAGE_SIZE); 148 if (imgp->stringbase == NULL) { 149 error = ENOMEM; 150 goto exec_fail; 151 } 152 imgp->stringp = imgp->stringbase; 153 imgp->stringspace = ARG_MAX; 154 imgp->image_header = imgp->stringbase + ARG_MAX; 155 156 /* 157 * Translate the file name. namei() returns a vnode pointer 158 * in ni_vp amoung other things. 159 */ 160 ndp = &nd; 161 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 162 UIO_USERSPACE, uap->fname, p); 163 164 interpret: 165 166 error = namei(ndp); 167 if (error) { 168 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase, 169 ARG_MAX + PAGE_SIZE); 170 goto exec_fail; 171 } 172 173 imgp->vp = ndp->ni_vp; 174 imgp->fname = uap->fname; 175 176 /* 177 * Check file permissions (also 'opens' file) 178 */ 179 error = exec_check_permissions(imgp); 180 if (error) { 181 VOP_UNLOCK(imgp->vp, 0, p); 182 goto exec_fail_dealloc; 183 } 184 185 error = exec_map_first_page(imgp); 186 VOP_UNLOCK(imgp->vp, 0, p); 187 if (error) 188 goto exec_fail_dealloc; 189 190 /* 191 * If the current process has a special image activator it 192 * wants to try first, call it. For example, emulating shell 193 * scripts differently. 194 */ 195 error = -1; 196 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 197 error = img_first(imgp); 198 199 /* 200 * Loop through the list of image activators, calling each one. 201 * An activator returns -1 if there is no match, 0 on success, 202 * and an error otherwise. 203 */ 204 for (i = 0; error == -1 && execsw[i]; ++i) { 205 if (execsw[i]->ex_imgact == NULL || 206 execsw[i]->ex_imgact == img_first) { 207 continue; 208 } 209 error = (*execsw[i]->ex_imgact)(imgp); 210 } 211 212 if (error) { 213 if (error == -1) 214 error = ENOEXEC; 215 goto exec_fail_dealloc; 216 } 217 218 /* 219 * Special interpreter operation, cleanup and loop up to try to 220 * activate the interpreter. 221 */ 222 if (imgp->interpreted) { 223 exec_unmap_first_page(imgp); 224 /* free name buffer and old vnode */ 225 NDFREE(ndp, NDF_ONLY_PNBUF); 226 vrele(ndp->ni_vp); 227 /* set new name to that of the interpreter */ 228 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 229 UIO_SYSSPACE, imgp->interpreter_name, p); 230 goto interpret; 231 } 232 233 /* 234 * Copy out strings (args and env) and initialize stack base 235 */ 236 stack_base = exec_copyout_strings(imgp); 237 p->p_vmspace->vm_minsaddr = (char *)stack_base; 238 239 /* 240 * If custom stack fixup routine present for this process 241 * let it do the stack setup. 242 * Else stuff argument count as first item on stack 243 */ 244 if (p->p_sysent->sv_fixup) 245 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 246 else 247 suword(--stack_base, imgp->argc); 248 249 /* 250 * For security and other reasons, the file descriptor table cannot 251 * be shared after an exec. 252 */ 253 if (p->p_fd->fd_refcnt > 1) { 254 struct filedesc *tmp; 255 256 tmp = fdcopy(p); 257 fdfree(p); 258 p->p_fd = tmp; 259 } 260 261 /* 262 * For security and other reasons, signal handlers cannot 263 * be shared after an exec. The new proces gets a copy of the old 264 * handlers. In execsigs(), the new process will have its signals 265 * reset. 266 */ 267 if (p->p_procsig->ps_refcnt > 1) { 268 struct procsig *newprocsig; 269 270 MALLOC(newprocsig, struct procsig *, sizeof(struct procsig), 271 M_SUBPROC, M_WAITOK); 272 bcopy(p->p_procsig, newprocsig, sizeof(*newprocsig)); 273 p->p_procsig->ps_refcnt--; 274 p->p_procsig = newprocsig; 275 p->p_procsig->ps_refcnt = 1; 276 if (p->p_sigacts == &p->p_addr->u_sigacts) 277 panic("shared procsig but private sigacts?"); 278 279 p->p_addr->u_sigacts = *p->p_sigacts; 280 p->p_sigacts = &p->p_addr->u_sigacts; 281 } 282 283 /* Stop profiling */ 284 stopprofclock(p); 285 286 /* close files on exec */ 287 fdcloseexec(p); 288 289 /* reset caught signals */ 290 execsigs(p); 291 292 /* name this process - nameiexec(p, ndp) */ 293 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 294 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 295 p->p_comm[len] = 0; 296 297 /* 298 * mark as execed, wakeup the process that vforked (if any) and tell 299 * it that it now has its own resources back 300 */ 301 p->p_flag |= P_EXEC; 302 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 303 p->p_flag &= ~P_PPWAIT; 304 wakeup((caddr_t)p->p_pptr); 305 } 306 307 /* 308 * Implement image setuid/setgid. 309 * 310 * Don't honor setuid/setgid if the filesystem prohibits it or if 311 * the process is being traced. 312 */ 313 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 314 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 315 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 316 (p->p_flag & P_TRACED) == 0) { 317 /* 318 * Turn off syscall tracing for set-id programs, except for 319 * root. Record any set-id flags first to make sure that 320 * we do not regain any tracing during a possible block. 321 */ 322 setsugid(p); 323 if (p->p_tracep && suser(p)) { 324 struct vnode *vtmp; 325 326 if ((vtmp = p->p_tracep) != NULL) { 327 p->p_tracep = NULL; 328 p->p_traceflag = 0; 329 vrele(vtmp); 330 } 331 } 332 /* Close any file descriptors 0..2 that reference procfs */ 333 setugidsafety(p); 334 /* Make sure file descriptors 0..2 are in use. */ 335 error = fdcheckstd(p); 336 if (error != 0) 337 goto exec_fail_dealloc; 338 /* 339 * Set the new credentials. 340 */ 341 p->p_ucred = crcopy(p->p_ucred); 342 if (attr.va_mode & VSUID) 343 change_euid(p, attr.va_uid); 344 if (attr.va_mode & VSGID) 345 p->p_ucred->cr_gid = attr.va_gid; 346 } else { 347 if (p->p_ucred->cr_uid == p->p_cred->p_ruid && 348 p->p_ucred->cr_gid == p->p_cred->p_rgid) 349 p->p_flag &= ~P_SUGID; 350 } 351 352 /* 353 * Implement correct POSIX saved-id behavior. 354 */ 355 p->p_cred->p_svuid = p->p_ucred->cr_uid; 356 p->p_cred->p_svgid = p->p_ucred->cr_gid; 357 358 /* 359 * Store the vp for use in procfs 360 */ 361 if (p->p_textvp) /* release old reference */ 362 vrele(p->p_textvp); 363 VREF(ndp->ni_vp); 364 p->p_textvp = ndp->ni_vp; 365 366 /* 367 * Notify others that we exec'd, and clear the P_INEXEC flag 368 * as we're now a bona fide freshly-execed process. 369 */ 370 KNOTE(&p->p_klist, NOTE_EXEC); 371 p->p_flag &= ~P_INEXEC; 372 373 /* 374 * If tracing the process, trap to debugger so breakpoints 375 * can be set before the program executes. 376 */ 377 STOPEVENT(p, S_EXEC, 0); 378 379 if (p->p_flag & P_TRACED) 380 psignal(p, SIGTRAP); 381 382 /* clear "fork but no exec" flag, as we _are_ execing */ 383 p->p_acflag &= ~AFORK; 384 385 /* Set values passed into the program in registers. */ 386 setregs(p, imgp->entry_addr, (u_long)(uintptr_t)stack_base, 387 imgp->ps_strings); 388 389 /* Free any previous argument cache */ 390 if (p->p_args && --p->p_args->ar_ref == 0) 391 FREE(p->p_args, M_PARGS); 392 p->p_args = NULL; 393 394 /* Cache arguments if they fit inside our allowance */ 395 i = imgp->endargs - imgp->stringbase; 396 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 397 MALLOC(p->p_args, struct pargs *, sizeof(struct pargs) + i, 398 M_PARGS, M_WAITOK); 399 p->p_args->ar_ref = 1; 400 p->p_args->ar_length = i; 401 bcopy(imgp->stringbase, p->p_args->ar_args, i); 402 } 403 404 exec_fail_dealloc: 405 406 /* 407 * free various allocated resources 408 */ 409 if (imgp->firstpage) 410 exec_unmap_first_page(imgp); 411 412 if (imgp->stringbase != NULL) 413 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase, 414 ARG_MAX + PAGE_SIZE); 415 416 if (imgp->vp) { 417 NDFREE(ndp, NDF_ONLY_PNBUF); 418 vrele(imgp->vp); 419 } 420 421 if (error == 0) 422 return (0); 423 424 exec_fail: 425 /* we're done here, clear P_INEXEC */ 426 p->p_flag &= ~P_INEXEC; 427 if (imgp->vmspace_destroyed) { 428 /* sorry, no more process anymore. exit gracefully */ 429 exit1(p, W_EXITCODE(0, SIGABRT)); 430 /* NOT REACHED */ 431 return(0); 432 } else { 433 return(error); 434 } 435 } 436 437 int 438 exec_map_first_page(imgp) 439 struct image_params *imgp; 440 { 441 int s, rv, i; 442 int initial_pagein; 443 vm_page_t ma[VM_INITIAL_PAGEIN]; 444 vm_object_t object; 445 446 447 if (imgp->firstpage) { 448 exec_unmap_first_page(imgp); 449 } 450 451 VOP_GETVOBJECT(imgp->vp, &object); 452 s = splvm(); 453 454 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 455 456 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 457 initial_pagein = VM_INITIAL_PAGEIN; 458 if (initial_pagein > object->size) 459 initial_pagein = object->size; 460 for (i = 1; i < initial_pagein; i++) { 461 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 462 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy) 463 break; 464 if (ma[i]->valid) 465 break; 466 vm_page_busy(ma[i]); 467 } else { 468 ma[i] = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 469 if (ma[i] == NULL) 470 break; 471 } 472 } 473 initial_pagein = i; 474 475 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 476 ma[0] = vm_page_lookup(object, 0); 477 478 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || (ma[0]->valid == 0)) { 479 if (ma[0]) { 480 vm_page_protect(ma[0], VM_PROT_NONE); 481 vm_page_free(ma[0]); 482 } 483 splx(s); 484 return EIO; 485 } 486 } 487 488 vm_page_wire(ma[0]); 489 vm_page_wakeup(ma[0]); 490 splx(s); 491 492 pmap_kenter((vm_offset_t) imgp->image_header, VM_PAGE_TO_PHYS(ma[0])); 493 imgp->firstpage = ma[0]; 494 495 return 0; 496 } 497 498 void 499 exec_unmap_first_page(imgp) 500 struct image_params *imgp; 501 { 502 if (imgp->firstpage) { 503 pmap_kremove((vm_offset_t) imgp->image_header); 504 vm_page_unwire(imgp->firstpage, 1); 505 imgp->firstpage = NULL; 506 } 507 } 508 509 /* 510 * Destroy old address space, and allocate a new stack 511 * The new stack is only SGROWSIZ large because it is grown 512 * automatically in trap.c. 513 */ 514 int 515 exec_new_vmspace(imgp) 516 struct image_params *imgp; 517 { 518 int error; 519 struct vmspace *vmspace = imgp->proc->p_vmspace; 520 vm_offset_t stack_addr = USRSTACK - maxssiz; 521 vm_map_t map = &vmspace->vm_map; 522 523 imgp->vmspace_destroyed = 1; 524 525 /* 526 * Prevent a pending AIO from modifying the new address space. 527 */ 528 aio_proc_rundown(imgp->proc); 529 530 /* 531 * Blow away entire process VM, if address space not shared, 532 * otherwise, create a new VM space so that other threads are 533 * not disrupted 534 */ 535 if (vmspace->vm_refcnt == 1) { 536 if (vmspace->vm_shm) 537 shmexit(imgp->proc); 538 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); 539 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); 540 } else { 541 vmspace_exec(imgp->proc); 542 vmspace = imgp->proc->p_vmspace; 543 map = &vmspace->vm_map; 544 } 545 546 /* Allocate a new stack */ 547 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 548 VM_PROT_ALL, VM_PROT_ALL, 0); 549 if (error) 550 return (error); 551 552 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 553 * VM_STACK case, but they are still used to monitor the size of the 554 * process stack so we can check the stack rlimit. 555 */ 556 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 557 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 558 559 return(0); 560 } 561 562 /* 563 * Copy out argument and environment strings from the old process 564 * address space into the temporary string buffer. 565 */ 566 int 567 exec_extract_strings(imgp) 568 struct image_params *imgp; 569 { 570 char **argv, **envv; 571 char *argp, *envp; 572 int error; 573 size_t length; 574 575 /* 576 * extract arguments first 577 */ 578 579 argv = imgp->uap->argv; 580 581 if (argv) { 582 argp = (caddr_t) (intptr_t) fuword(argv); 583 if (argp == (caddr_t) -1) 584 return (EFAULT); 585 if (argp) 586 argv++; 587 if (imgp->argv0) 588 argp = imgp->argv0; 589 if (argp) { 590 do { 591 if (argp == (caddr_t) -1) 592 return (EFAULT); 593 if ((error = copyinstr(argp, imgp->stringp, 594 imgp->stringspace, &length))) { 595 if (error == ENAMETOOLONG) 596 return(E2BIG); 597 return (error); 598 } 599 imgp->stringspace -= length; 600 imgp->stringp += length; 601 imgp->argc++; 602 } while ((argp = (caddr_t) (intptr_t) fuword(argv++))); 603 } 604 } 605 606 imgp->endargs = imgp->stringp; 607 608 /* 609 * extract environment strings 610 */ 611 612 envv = imgp->uap->envv; 613 614 if (envv) { 615 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 616 if (envp == (caddr_t) -1) 617 return (EFAULT); 618 if ((error = copyinstr(envp, imgp->stringp, 619 imgp->stringspace, &length))) { 620 if (error == ENAMETOOLONG) 621 return(E2BIG); 622 return (error); 623 } 624 imgp->stringspace -= length; 625 imgp->stringp += length; 626 imgp->envc++; 627 } 628 } 629 630 return (0); 631 } 632 633 /* 634 * Copy strings out to the new process address space, constructing 635 * new arg and env vector tables. Return a pointer to the base 636 * so that it can be used as the initial stack pointer. 637 */ 638 register_t * 639 exec_copyout_strings(imgp) 640 struct image_params *imgp; 641 { 642 int argc, envc; 643 char **vectp; 644 char *stringp, *destp; 645 register_t *stack_base; 646 struct ps_strings *arginfo; 647 int szsigcode; 648 649 /* 650 * Calculate string base and vector table pointers. 651 * Also deal with signal trampoline code for this exec type. 652 */ 653 arginfo = (struct ps_strings *)PS_STRINGS; 654 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 655 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 656 roundup((ARG_MAX - imgp->stringspace), sizeof(char *)); 657 658 /* 659 * install sigcode 660 */ 661 if (szsigcode) 662 copyout(imgp->proc->p_sysent->sv_sigcode, 663 ((caddr_t)arginfo - szsigcode), szsigcode); 664 665 /* 666 * If we have a valid auxargs ptr, prepare some room 667 * on the stack. 668 */ 669 if (imgp->auxargs) 670 /* 671 * The '+ 2' is for the null pointers at the end of each of the 672 * arg and env vector sets, and 'AT_COUNT*2' is room for the 673 * ELF Auxargs data. 674 */ 675 vectp = (char **)(destp - (imgp->argc + imgp->envc + 2 + 676 AT_COUNT*2) * sizeof(char*)); 677 else 678 /* 679 * The '+ 2' is for the null pointers at the end of each of the 680 * arg and env vector sets 681 */ 682 vectp = (char **) 683 (destp - (imgp->argc + imgp->envc + 2) * sizeof(char*)); 684 685 /* 686 * vectp also becomes our initial stack base 687 */ 688 stack_base = (register_t *)vectp; 689 690 stringp = imgp->stringbase; 691 argc = imgp->argc; 692 envc = imgp->envc; 693 694 /* 695 * Copy out strings - arguments and environment. 696 */ 697 copyout(stringp, destp, ARG_MAX - imgp->stringspace); 698 699 /* 700 * Fill in "ps_strings" struct for ps, w, etc. 701 */ 702 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 703 suword(&arginfo->ps_nargvstr, argc); 704 705 /* 706 * Fill in argument portion of vector table. 707 */ 708 for (; argc > 0; --argc) { 709 suword(vectp++, (long)(intptr_t)destp); 710 while (*stringp++ != 0) 711 destp++; 712 destp++; 713 } 714 715 /* a null vector table pointer seperates the argp's from the envp's */ 716 suword(vectp++, 0); 717 718 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 719 suword(&arginfo->ps_nenvstr, envc); 720 721 /* 722 * Fill in environment portion of vector table. 723 */ 724 for (; envc > 0; --envc) { 725 suword(vectp++, (long)(intptr_t)destp); 726 while (*stringp++ != 0) 727 destp++; 728 destp++; 729 } 730 731 /* end of vector table is a null pointer */ 732 suword(vectp, 0); 733 734 return (stack_base); 735 } 736 737 /* 738 * Check permissions of file to execute. 739 * Return 0 for success or error code on failure. 740 */ 741 int 742 exec_check_permissions(imgp) 743 struct image_params *imgp; 744 { 745 struct proc *p = imgp->proc; 746 struct vnode *vp = imgp->vp; 747 struct vattr *attr = imgp->attr; 748 int error; 749 750 /* Get file attributes */ 751 error = VOP_GETATTR(vp, attr, p->p_ucred, p); 752 if (error) 753 return (error); 754 755 /* 756 * 1) Check if file execution is disabled for the filesystem that this 757 * file resides on. 758 * 2) Insure that at least one execute bit is on - otherwise root 759 * will always succeed, and we don't want to happen unless the 760 * file really is executable. 761 * 3) Insure that the file is a regular file. 762 */ 763 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 764 ((attr->va_mode & 0111) == 0) || 765 (attr->va_type != VREG)) { 766 return (EACCES); 767 } 768 769 /* 770 * Zero length files can't be exec'd 771 */ 772 if (attr->va_size == 0) 773 return (ENOEXEC); 774 775 /* 776 * Check for execute permission to file based on current credentials. 777 */ 778 error = VOP_ACCESS(vp, VEXEC, p->p_ucred, p); 779 if (error) 780 return (error); 781 782 /* 783 * Check number of open-for-writes on the file and deny execution 784 * if there are any. 785 */ 786 if (vp->v_writecount) 787 return (ETXTBSY); 788 789 /* 790 * Call filesystem specific open routine (which does nothing in the 791 * general case). 792 */ 793 error = VOP_OPEN(vp, FREAD, p->p_ucred, p); 794 if (error) 795 return (error); 796 797 return (0); 798 } 799 800 /* 801 * Exec handler registration 802 */ 803 int 804 exec_register(execsw_arg) 805 const struct execsw *execsw_arg; 806 { 807 const struct execsw **es, **xs, **newexecsw; 808 int count = 2; /* New slot and trailing NULL */ 809 810 if (execsw) 811 for (es = execsw; *es; es++) 812 count++; 813 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 814 if (newexecsw == NULL) 815 return ENOMEM; 816 xs = newexecsw; 817 if (execsw) 818 for (es = execsw; *es; es++) 819 *xs++ = *es; 820 *xs++ = execsw_arg; 821 *xs = NULL; 822 if (execsw) 823 free(execsw, M_TEMP); 824 execsw = newexecsw; 825 return 0; 826 } 827 828 int 829 exec_unregister(execsw_arg) 830 const struct execsw *execsw_arg; 831 { 832 const struct execsw **es, **xs, **newexecsw; 833 int count = 1; 834 835 if (execsw == NULL) 836 panic("unregister with no handlers left?\n"); 837 838 for (es = execsw; *es; es++) { 839 if (*es == execsw_arg) 840 break; 841 } 842 if (*es == NULL) 843 return ENOENT; 844 for (es = execsw; *es; es++) 845 if (*es != execsw_arg) 846 count++; 847 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 848 if (newexecsw == NULL) 849 return ENOMEM; 850 xs = newexecsw; 851 for (es = execsw; *es; es++) 852 if (*es != execsw_arg) 853 *xs++ = *es; 854 *xs = NULL; 855 if (execsw) 856 free(execsw, M_TEMP); 857 execsw = newexecsw; 858 return 0; 859 } 860