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 * $FreeBSD$ 27 */ 28 29 #include <sys/param.h> 30 #include <sys/systm.h> 31 #include <sys/lock.h> 32 #include <sys/mutex.h> 33 #include <sys/sysproto.h> 34 #include <sys/signalvar.h> 35 #include <sys/kernel.h> 36 #include <sys/mount.h> 37 #include <sys/filedesc.h> 38 #include <sys/fcntl.h> 39 #include <sys/acct.h> 40 #include <sys/exec.h> 41 #include <sys/imgact.h> 42 #include <sys/imgact_elf.h> 43 #include <sys/wait.h> 44 #include <sys/proc.h> 45 #include <sys/pioctl.h> 46 #include <sys/malloc.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 53 #include <vm/vm.h> 54 #include <vm/vm_param.h> 55 #include <vm/pmap.h> 56 #include <vm/vm_page.h> 57 #include <vm/vm_map.h> 58 #include <vm/vm_kern.h> 59 #include <vm/vm_extern.h> 60 #include <vm/vm_object.h> 61 #include <vm/vm_pager.h> 62 63 #include <machine/reg.h> 64 65 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 66 67 static register_t *exec_copyout_strings __P((struct image_params *)); 68 69 /* XXX This should be vm_size_t. */ 70 static u_long ps_strings = PS_STRINGS; 71 SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, ""); 72 73 /* XXX This should be vm_size_t. */ 74 static u_long usrstack = USRSTACK; 75 SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, ""); 76 77 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 78 SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 79 &ps_arg_cache_limit, 0, ""); 80 81 int ps_argsopen = 1; 82 SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, ""); 83 84 /* 85 * Each of the items is a pointer to a `const struct execsw', hence the 86 * double pointer here. 87 */ 88 static const struct execsw **execsw; 89 90 #ifndef _SYS_SYSPROTO_H_ 91 struct execve_args { 92 char *fname; 93 char **argv; 94 char **envv; 95 }; 96 #endif 97 98 /* 99 * execve() system call. 100 */ 101 int 102 execve(p, uap) 103 struct proc *p; 104 register struct execve_args *uap; 105 { 106 struct nameidata nd, *ndp; 107 struct ucred *newcred, *oldcred; 108 register_t *stack_base; 109 int error, len, i; 110 struct image_params image_params, *imgp; 111 struct vattr attr; 112 int (*img_first) __P((struct image_params *)); 113 struct pargs *pa; 114 115 imgp = &image_params; 116 117 /* 118 * Initialize part of the common data 119 */ 120 imgp->proc = p; 121 imgp->uap = uap; 122 imgp->attr = &attr; 123 imgp->argc = imgp->envc = 0; 124 imgp->argv0 = NULL; 125 imgp->entry_addr = 0; 126 imgp->vmspace_destroyed = 0; 127 imgp->interpreted = 0; 128 imgp->interpreter_name[0] = '\0'; 129 imgp->auxargs = NULL; 130 imgp->vp = NULL; 131 imgp->firstpage = NULL; 132 imgp->ps_strings = 0; 133 imgp->auxarg_size = 0; 134 135 /* 136 * Allocate temporary demand zeroed space for argument and 137 * environment strings 138 */ 139 imgp->stringbase = (char *)kmem_alloc_wait(exec_map, ARG_MAX + PAGE_SIZE); 140 if (imgp->stringbase == NULL) { 141 error = ENOMEM; 142 goto exec_fail; 143 } 144 imgp->stringp = imgp->stringbase; 145 imgp->stringspace = ARG_MAX; 146 imgp->image_header = imgp->stringbase + ARG_MAX; 147 148 /* 149 * Translate the file name. namei() returns a vnode pointer 150 * in ni_vp amoung other things. 151 */ 152 ndp = &nd; 153 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 154 UIO_USERSPACE, uap->fname, p); 155 156 interpret: 157 158 error = namei(ndp); 159 if (error) { 160 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase, 161 ARG_MAX + PAGE_SIZE); 162 goto exec_fail; 163 } 164 165 imgp->vp = ndp->ni_vp; 166 imgp->fname = uap->fname; 167 168 /* 169 * Check file permissions (also 'opens' file) 170 */ 171 error = exec_check_permissions(imgp); 172 if (error) { 173 VOP_UNLOCK(imgp->vp, 0, p); 174 goto exec_fail_dealloc; 175 } 176 177 error = exec_map_first_page(imgp); 178 VOP_UNLOCK(imgp->vp, 0, p); 179 if (error) 180 goto exec_fail_dealloc; 181 182 /* 183 * If the current process has a special image activator it 184 * wants to try first, call it. For example, emulating shell 185 * scripts differently. 186 */ 187 error = -1; 188 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 189 error = img_first(imgp); 190 191 /* 192 * Loop through the list of image activators, calling each one. 193 * An activator returns -1 if there is no match, 0 on success, 194 * and an error otherwise. 195 */ 196 for (i = 0; error == -1 && execsw[i]; ++i) { 197 if (execsw[i]->ex_imgact == NULL || 198 execsw[i]->ex_imgact == img_first) { 199 continue; 200 } 201 error = (*execsw[i]->ex_imgact)(imgp); 202 } 203 204 if (error) { 205 if (error == -1) 206 error = ENOEXEC; 207 goto exec_fail_dealloc; 208 } 209 210 /* 211 * Special interpreter operation, cleanup and loop up to try to 212 * activate the interpreter. 213 */ 214 if (imgp->interpreted) { 215 exec_unmap_first_page(imgp); 216 /* free name buffer and old vnode */ 217 NDFREE(ndp, NDF_ONLY_PNBUF); 218 vrele(ndp->ni_vp); 219 /* set new name to that of the interpreter */ 220 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 221 UIO_SYSSPACE, imgp->interpreter_name, p); 222 goto interpret; 223 } 224 225 /* 226 * Copy out strings (args and env) and initialize stack base 227 */ 228 stack_base = exec_copyout_strings(imgp); 229 p->p_vmspace->vm_minsaddr = (char *)stack_base; 230 231 /* 232 * If custom stack fixup routine present for this process 233 * let it do the stack setup. 234 * Else stuff argument count as first item on stack 235 */ 236 if (p->p_sysent->sv_fixup) 237 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 238 else 239 suword(--stack_base, imgp->argc); 240 241 /* 242 * For security and other reasons, the file descriptor table cannot 243 * be shared after an exec. 244 */ 245 if (p->p_fd->fd_refcnt > 1) { 246 struct filedesc *tmp; 247 248 tmp = fdcopy(p); 249 fdfree(p); 250 p->p_fd = tmp; 251 } 252 253 /* Stop profiling */ 254 stopprofclock(p); 255 256 /* close files on exec */ 257 fdcloseexec(p); 258 259 /* reset caught signals */ 260 execsigs(p); 261 262 /* name this process - nameiexec(p, ndp) */ 263 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 264 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 265 p->p_comm[len] = 0; 266 267 /* 268 * mark as execed, wakeup the process that vforked (if any) and tell 269 * it that it now has its own resources back 270 */ 271 PROC_LOCK(p); 272 p->p_flag |= P_EXEC; 273 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 274 p->p_flag &= ~P_PPWAIT; 275 wakeup((caddr_t)p->p_pptr); 276 } 277 278 /* 279 * XXX: Note, the whole execve() is incredibly racey right now 280 * with regards to debugging and privilege/credential management. 281 * In particular, it's possible to race during exec() to attach 282 * debugging to a process that will gain privilege. 283 * 284 * This MUST be fixed prior to any release. 285 */ 286 287 /* 288 * Implement image setuid/setgid. 289 * 290 * Don't honor setuid/setgid if the filesystem prohibits it or if 291 * the process is being traced. 292 */ 293 oldcred = p->p_ucred; 294 newcred = NULL; 295 if ((((attr.va_mode & VSUID) && oldcred->cr_uid != attr.va_uid) || 296 ((attr.va_mode & VSGID) && oldcred->cr_gid != attr.va_gid)) && 297 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 298 (p->p_flag & P_TRACED) == 0) { 299 PROC_UNLOCK(p); 300 /* 301 * Turn off syscall tracing for set-id programs, except for 302 * root. Record any set-id flags first to make sure that 303 * we do not regain any tracing during a possible block. 304 */ 305 setsugid(p); 306 if (p->p_tracep && suser_xxx(oldcred, NULL, PRISON_ROOT)) { 307 p->p_traceflag = 0; 308 vrele(p->p_tracep); 309 p->p_tracep = NULL; 310 } 311 /* 312 * Set the new credentials. 313 */ 314 newcred = crdup(oldcred); 315 if (attr.va_mode & VSUID) 316 change_euid(newcred, attr.va_uid); 317 if (attr.va_mode & VSGID) 318 change_egid(newcred, attr.va_gid); 319 setugidsafety(p); 320 } else { 321 if (oldcred->cr_uid == oldcred->cr_ruid && 322 oldcred->cr_gid == oldcred->cr_rgid) 323 p->p_flag &= ~P_SUGID; 324 PROC_UNLOCK(p); 325 } 326 327 /* 328 * Implement correct POSIX saved-id behavior. 329 * 330 * XXX: It's not clear that the existing behavior is 331 * POSIX-compliant. A number of sourses indicate that the saved 332 * uid/gid should only be updated if the new ruid is not equal to 333 * the old ruid, or the new euid is not equal to the old euid and 334 * the new euid is not equal to the old ruid. The FreeBSD code 335 * always updates the saved uid/gid. Also, this code uses the new 336 * (replaced) euid and egid as the source, which may or may not be 337 * the right ones to use. 338 */ 339 if (newcred == NULL) { 340 if (oldcred->cr_svuid != oldcred->cr_uid || 341 oldcred->cr_svgid != oldcred->cr_gid) { 342 newcred = crdup(oldcred); 343 change_svuid(newcred, newcred->cr_uid); 344 change_svgid(newcred, newcred->cr_gid); 345 } 346 } else { 347 change_svuid(newcred, newcred->cr_uid); 348 change_svgid(newcred, newcred->cr_gid); 349 } 350 351 if (newcred != NULL) { 352 PROC_LOCK(p); 353 p->p_ucred = newcred; 354 PROC_UNLOCK(p); 355 crfree(oldcred); 356 } 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 368 */ 369 PROC_LOCK(p); 370 KNOTE(&p->p_klist, NOTE_EXEC); 371 372 /* 373 * If tracing the process, trap to debugger so breakpoints 374 * can be set before the program executes. 375 */ 376 _STOPEVENT(p, S_EXEC, 0); 377 378 if (p->p_flag & P_TRACED) 379 psignal(p, SIGTRAP); 380 381 /* clear "fork but no exec" flag, as we _are_ execing */ 382 p->p_acflag &= ~AFORK; 383 384 /* Set values passed into the program in registers. */ 385 setregs(p, imgp->entry_addr, (u_long)(uintptr_t)stack_base, 386 imgp->ps_strings); 387 388 /* Free any previous argument cache */ 389 pa = p->p_args; 390 p->p_args = NULL; 391 PROC_UNLOCK(p); 392 if (pa != NULL && --pa->ar_ref == 0) 393 FREE(pa, M_PARGS); 394 395 /* Cache arguments if they fit inside our allowance */ 396 i = imgp->endargs - imgp->stringbase; 397 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 398 MALLOC(pa, struct pargs *, sizeof(struct pargs) + i, 399 M_PARGS, M_WAITOK); 400 pa->ar_ref = 1; 401 pa->ar_length = i; 402 bcopy(imgp->stringbase, pa->ar_args, i); 403 PROC_LOCK(p); 404 p->p_args = pa; 405 PROC_UNLOCK(p); 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 if (imgp->vmspace_destroyed) { 430 /* sorry, no more process anymore. exit gracefully */ 431 exit1(p, W_EXITCODE(0, SIGABRT)); 432 /* NOT REACHED */ 433 return(0); 434 } else { 435 return(error); 436 } 437 } 438 439 int 440 exec_map_first_page(imgp) 441 struct image_params *imgp; 442 { 443 int rv, i; 444 int initial_pagein; 445 vm_page_t ma[VM_INITIAL_PAGEIN]; 446 vm_object_t object; 447 448 449 if (imgp->firstpage) { 450 exec_unmap_first_page(imgp); 451 } 452 453 VOP_GETVOBJECT(imgp->vp, &object); 454 mtx_lock(&vm_mtx); 455 456 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 457 458 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 459 initial_pagein = VM_INITIAL_PAGEIN; 460 if (initial_pagein > object->size) 461 initial_pagein = object->size; 462 for (i = 1; i < initial_pagein; i++) { 463 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 464 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy) 465 break; 466 if (ma[i]->valid) 467 break; 468 vm_page_busy(ma[i]); 469 } else { 470 ma[i] = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 471 if (ma[i] == NULL) 472 break; 473 } 474 } 475 initial_pagein = i; 476 477 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 478 ma[0] = vm_page_lookup(object, 0); 479 480 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || (ma[0]->valid == 0)) { 481 if (ma[0]) { 482 vm_page_protect(ma[0], VM_PROT_NONE); 483 vm_page_free(ma[0]); 484 } 485 mtx_unlock(&vm_mtx); 486 return EIO; 487 } 488 } 489 490 vm_page_wire(ma[0]); 491 vm_page_wakeup(ma[0]); 492 493 pmap_kenter((vm_offset_t) imgp->image_header, VM_PAGE_TO_PHYS(ma[0])); 494 imgp->firstpage = ma[0]; 495 496 mtx_unlock(&vm_mtx); 497 return 0; 498 } 499 500 void 501 exec_unmap_first_page(imgp) 502 struct image_params *imgp; 503 { 504 505 if (imgp->firstpage) { 506 mtx_lock(&vm_mtx); 507 pmap_kremove((vm_offset_t) imgp->image_header); 508 vm_page_unwire(imgp->firstpage, 1); 509 mtx_unlock(&vm_mtx); 510 imgp->firstpage = NULL; 511 } 512 } 513 514 /* 515 * Destroy old address space, and allocate a new stack 516 * The new stack is only SGROWSIZ large because it is grown 517 * automatically in trap.c. 518 */ 519 int 520 exec_new_vmspace(imgp) 521 struct image_params *imgp; 522 { 523 int error; 524 struct vmspace *vmspace = imgp->proc->p_vmspace; 525 caddr_t stack_addr = (caddr_t) (USRSTACK - MAXSSIZ); 526 vm_map_t map = &vmspace->vm_map; 527 528 mtx_assert(&vm_mtx, MA_OWNED); 529 imgp->vmspace_destroyed = 1; 530 531 /* 532 * Blow away entire process VM, if address space not shared, 533 * otherwise, create a new VM space so that other threads are 534 * not disrupted 535 */ 536 if (vmspace->vm_refcnt == 1) { 537 if (vmspace->vm_shm) 538 shmexit(imgp->proc); 539 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); 540 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); 541 } else { 542 vmspace_exec(imgp->proc); 543 vmspace = imgp->proc->p_vmspace; 544 map = &vmspace->vm_map; 545 } 546 547 /* Allocate a new stack */ 548 error = vm_map_stack (&vmspace->vm_map, (vm_offset_t)stack_addr, 549 (vm_size_t)MAXSSIZ, VM_PROT_ALL, VM_PROT_ALL, 0); 550 if (error) 551 return (error); 552 553 #ifdef __ia64__ 554 { 555 /* 556 * Allocate backing store. We really need something 557 * similar to vm_map_stack which can allow the backing 558 * store to grow upwards. This will do for now. 559 */ 560 vm_offset_t bsaddr; 561 bsaddr = USRSTACK - 2*MAXSSIZ; 562 error = vm_map_find(&vmspace->vm_map, 0, 0, &bsaddr, 563 4*PAGE_SIZE, 0, 564 VM_PROT_ALL, VM_PROT_ALL, 0); 565 imgp->proc->p_md.md_bspstore = bsaddr; 566 } 567 #endif 568 569 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 570 * VM_STACK case, but they are still used to monitor the size of the 571 * process stack so we can check the stack rlimit. 572 */ 573 vmspace->vm_ssize = SGROWSIZ >> PAGE_SHIFT; 574 vmspace->vm_maxsaddr = (char *)USRSTACK - MAXSSIZ; 575 576 return(0); 577 } 578 579 /* 580 * Copy out argument and environment strings from the old process 581 * address space into the temporary string buffer. 582 */ 583 int 584 exec_extract_strings(imgp) 585 struct image_params *imgp; 586 { 587 char **argv, **envv; 588 char *argp, *envp; 589 int error; 590 size_t length; 591 592 /* 593 * extract arguments first 594 */ 595 596 argv = imgp->uap->argv; 597 598 if (argv) { 599 argp = (caddr_t) (intptr_t) fuword(argv); 600 if (argp == (caddr_t) -1) 601 return (EFAULT); 602 if (argp) 603 argv++; 604 if (imgp->argv0) 605 argp = imgp->argv0; 606 if (argp) { 607 do { 608 if (argp == (caddr_t) -1) 609 return (EFAULT); 610 if ((error = copyinstr(argp, imgp->stringp, 611 imgp->stringspace, &length))) { 612 if (error == ENAMETOOLONG) 613 return(E2BIG); 614 return (error); 615 } 616 imgp->stringspace -= length; 617 imgp->stringp += length; 618 imgp->argc++; 619 } while ((argp = (caddr_t) (intptr_t) fuword(argv++))); 620 } 621 } 622 623 imgp->endargs = imgp->stringp; 624 625 /* 626 * extract environment strings 627 */ 628 629 envv = imgp->uap->envv; 630 631 if (envv) { 632 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 633 if (envp == (caddr_t) -1) 634 return (EFAULT); 635 if ((error = copyinstr(envp, imgp->stringp, 636 imgp->stringspace, &length))) { 637 if (error == ENAMETOOLONG) 638 return(E2BIG); 639 return (error); 640 } 641 imgp->stringspace -= length; 642 imgp->stringp += length; 643 imgp->envc++; 644 } 645 } 646 647 return (0); 648 } 649 650 /* 651 * Copy strings out to the new process address space, constructing 652 * new arg and env vector tables. Return a pointer to the base 653 * so that it can be used as the initial stack pointer. 654 */ 655 register_t * 656 exec_copyout_strings(imgp) 657 struct image_params *imgp; 658 { 659 int argc, envc; 660 char **vectp; 661 char *stringp, *destp; 662 register_t *stack_base; 663 struct ps_strings *arginfo; 664 int szsigcode; 665 666 /* 667 * Calculate string base and vector table pointers. 668 * Also deal with signal trampoline code for this exec type. 669 */ 670 arginfo = (struct ps_strings *)PS_STRINGS; 671 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 672 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 673 roundup((ARG_MAX - imgp->stringspace), sizeof(char *)); 674 675 /* 676 * install sigcode 677 */ 678 if (szsigcode) 679 copyout(imgp->proc->p_sysent->sv_sigcode, 680 ((caddr_t)arginfo - szsigcode), szsigcode); 681 682 /* 683 * If we have a valid auxargs ptr, prepare some room 684 * on the stack. 685 */ 686 if (imgp->auxargs) { 687 /* 688 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 689 * lower compatibility. 690 */ 691 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size 692 : (AT_COUNT * 2); 693 /* 694 * The '+ 2' is for the null pointers at the end of each of 695 * the arg and env vector sets,and imgp->auxarg_size is room 696 * for argument of Runtime loader. 697 */ 698 vectp = (char **) (destp - (imgp->argc + imgp->envc + 2 + 699 imgp->auxarg_size) * sizeof(char *)); 700 701 } else 702 /* 703 * The '+ 2' is for the null pointers at the end of each of 704 * the arg and env vector sets 705 */ 706 vectp = (char **) 707 (destp - (imgp->argc + imgp->envc + 2) * sizeof(char *)); 708 709 /* 710 * vectp also becomes our initial stack base 711 */ 712 stack_base = (register_t *)vectp; 713 714 stringp = imgp->stringbase; 715 argc = imgp->argc; 716 envc = imgp->envc; 717 718 /* 719 * Copy out strings - arguments and environment. 720 */ 721 copyout(stringp, destp, ARG_MAX - imgp->stringspace); 722 723 /* 724 * Fill in "ps_strings" struct for ps, w, etc. 725 */ 726 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 727 suword(&arginfo->ps_nargvstr, argc); 728 729 /* 730 * Fill in argument portion of vector table. 731 */ 732 for (; argc > 0; --argc) { 733 suword(vectp++, (long)(intptr_t)destp); 734 while (*stringp++ != 0) 735 destp++; 736 destp++; 737 } 738 739 /* a null vector table pointer separates the argp's from the envp's */ 740 suword(vectp++, 0); 741 742 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 743 suword(&arginfo->ps_nenvstr, envc); 744 745 /* 746 * Fill in environment portion of vector table. 747 */ 748 for (; envc > 0; --envc) { 749 suword(vectp++, (long)(intptr_t)destp); 750 while (*stringp++ != 0) 751 destp++; 752 destp++; 753 } 754 755 /* end of vector table is a null pointer */ 756 suword(vectp, 0); 757 758 return (stack_base); 759 } 760 761 /* 762 * Check permissions of file to execute. 763 * Called with imgp->vp locked. 764 * Return 0 for success or error code on failure. 765 */ 766 int 767 exec_check_permissions(imgp) 768 struct image_params *imgp; 769 { 770 struct proc *p = imgp->proc; 771 struct vnode *vp = imgp->vp; 772 struct vattr *attr = imgp->attr; 773 int error; 774 775 /* Get file attributes */ 776 error = VOP_GETATTR(vp, attr, p->p_ucred, p); 777 if (error) 778 return (error); 779 780 /* 781 * 1) Check if file execution is disabled for the filesystem that this 782 * file resides on. 783 * 2) Insure that at least one execute bit is on - otherwise root 784 * will always succeed, and we don't want to happen unless the 785 * file really is executable. 786 * 3) Insure that the file is a regular file. 787 */ 788 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 789 ((attr->va_mode & 0111) == 0) || 790 (attr->va_type != VREG)) { 791 return (EACCES); 792 } 793 794 /* 795 * Zero length files can't be exec'd 796 */ 797 if (attr->va_size == 0) 798 return (ENOEXEC); 799 800 /* 801 * Check for execute permission to file based on current credentials. 802 */ 803 error = VOP_ACCESS(vp, VEXEC, p->p_ucred, p); 804 if (error) 805 return (error); 806 807 /* 808 * Check number of open-for-writes on the file and deny execution 809 * if there are any. 810 */ 811 if (vp->v_writecount) 812 return (ETXTBSY); 813 814 /* 815 * Call filesystem specific open routine (which does nothing in the 816 * general case). 817 */ 818 error = VOP_OPEN(vp, FREAD, p->p_ucred, p); 819 if (error) 820 return (error); 821 822 return (0); 823 } 824 825 /* 826 * Exec handler registration 827 */ 828 int 829 exec_register(execsw_arg) 830 const struct execsw *execsw_arg; 831 { 832 const struct execsw **es, **xs, **newexecsw; 833 int count = 2; /* New slot and trailing NULL */ 834 835 if (execsw) 836 for (es = execsw; *es; es++) 837 count++; 838 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 839 if (newexecsw == NULL) 840 return ENOMEM; 841 xs = newexecsw; 842 if (execsw) 843 for (es = execsw; *es; es++) 844 *xs++ = *es; 845 *xs++ = execsw_arg; 846 *xs = NULL; 847 if (execsw) 848 free(execsw, M_TEMP); 849 execsw = newexecsw; 850 return 0; 851 } 852 853 int 854 exec_unregister(execsw_arg) 855 const struct execsw *execsw_arg; 856 { 857 const struct execsw **es, **xs, **newexecsw; 858 int count = 1; 859 860 if (execsw == NULL) 861 panic("unregister with no handlers left?\n"); 862 863 for (es = execsw; *es; es++) { 864 if (*es == execsw_arg) 865 break; 866 } 867 if (*es == NULL) 868 return ENOENT; 869 for (es = execsw; *es; es++) 870 if (*es != execsw_arg) 871 count++; 872 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 873 if (newexecsw == NULL) 874 return ENOMEM; 875 xs = newexecsw; 876 for (es = execsw; *es; es++) 877 if (*es != execsw_arg) 878 *xs++ = *es; 879 *xs = NULL; 880 if (execsw) 881 free(execsw, M_TEMP); 882 execsw = newexecsw; 883 return 0; 884 } 885