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 *)); 113 114 imgp = &image_params; 115 116 /* 117 * Initialize part of the common data 118 */ 119 imgp->proc = p; 120 imgp->uap = uap; 121 imgp->attr = &attr; 122 imgp->argc = imgp->envc = 0; 123 imgp->argv0 = NULL; 124 imgp->entry_addr = 0; 125 imgp->vmspace_destroyed = 0; 126 imgp->interpreted = 0; 127 imgp->interpreter_name[0] = '\0'; 128 imgp->auxargs = NULL; 129 imgp->vp = NULL; 130 imgp->firstpage = NULL; 131 imgp->ps_strings = 0; 132 imgp->auxarg_size = 0; 133 134 /* 135 * Allocate temporary demand zeroed space for argument and 136 * environment strings 137 */ 138 imgp->stringbase = (char *)kmem_alloc_wait(exec_map, ARG_MAX + PAGE_SIZE); 139 if (imgp->stringbase == NULL) { 140 error = ENOMEM; 141 goto exec_fail; 142 } 143 imgp->stringp = imgp->stringbase; 144 imgp->stringspace = ARG_MAX; 145 imgp->image_header = imgp->stringbase + ARG_MAX; 146 147 /* 148 * Translate the file name. namei() returns a vnode pointer 149 * in ni_vp amoung other things. 150 */ 151 ndp = &nd; 152 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 153 UIO_USERSPACE, uap->fname, p); 154 155 interpret: 156 157 error = namei(ndp); 158 if (error) { 159 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase, 160 ARG_MAX + PAGE_SIZE); 161 goto exec_fail; 162 } 163 164 imgp->vp = ndp->ni_vp; 165 imgp->fname = uap->fname; 166 167 /* 168 * Check file permissions (also 'opens' file) 169 */ 170 error = exec_check_permissions(imgp); 171 if (error) { 172 VOP_UNLOCK(imgp->vp, 0, p); 173 goto exec_fail_dealloc; 174 } 175 176 error = exec_map_first_page(imgp); 177 VOP_UNLOCK(imgp->vp, 0, p); 178 if (error) 179 goto exec_fail_dealloc; 180 181 /* 182 * If the current process has a special image activator it 183 * wants to try first, call it. For example, emulating shell 184 * scripts differently. 185 */ 186 error = -1; 187 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 188 error = img_first(imgp); 189 190 /* 191 * Loop through the list of image activators, calling each one. 192 * An activator returns -1 if there is no match, 0 on success, 193 * and an error otherwise. 194 */ 195 for (i = 0; error == -1 && execsw[i]; ++i) { 196 if (execsw[i]->ex_imgact == NULL || 197 execsw[i]->ex_imgact == img_first) { 198 continue; 199 } 200 error = (*execsw[i]->ex_imgact)(imgp); 201 } 202 203 if (error) { 204 if (error == -1) 205 error = ENOEXEC; 206 goto exec_fail_dealloc; 207 } 208 209 /* 210 * Special interpreter operation, cleanup and loop up to try to 211 * activate the interpreter. 212 */ 213 if (imgp->interpreted) { 214 exec_unmap_first_page(imgp); 215 /* free name buffer and old vnode */ 216 NDFREE(ndp, NDF_ONLY_PNBUF); 217 vrele(ndp->ni_vp); 218 /* set new name to that of the interpreter */ 219 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 220 UIO_SYSSPACE, imgp->interpreter_name, p); 221 goto interpret; 222 } 223 224 /* 225 * Copy out strings (args and env) and initialize stack base 226 */ 227 stack_base = exec_copyout_strings(imgp); 228 p->p_vmspace->vm_minsaddr = (char *)stack_base; 229 230 /* 231 * If custom stack fixup routine present for this process 232 * let it do the stack setup. 233 * Else stuff argument count as first item on stack 234 */ 235 if (p->p_sysent->sv_fixup) 236 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 237 else 238 suword(--stack_base, imgp->argc); 239 240 /* 241 * For security and other reasons, the file descriptor table cannot 242 * be shared after an exec. 243 */ 244 if (p->p_fd->fd_refcnt > 1) { 245 struct filedesc *tmp; 246 247 tmp = fdcopy(p); 248 fdfree(p); 249 p->p_fd = tmp; 250 } 251 252 /* Stop profiling */ 253 stopprofclock(p); 254 255 /* close files on exec */ 256 fdcloseexec(p); 257 258 /* reset caught signals */ 259 execsigs(p); 260 261 /* name this process - nameiexec(p, ndp) */ 262 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 263 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 264 p->p_comm[len] = 0; 265 266 /* 267 * mark as execed, wakeup the process that vforked (if any) and tell 268 * it that it now has its own resources back 269 */ 270 PROC_LOCK(p); 271 p->p_flag |= P_EXEC; 272 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 273 p->p_flag &= ~P_PPWAIT; 274 wakeup((caddr_t)p->p_pptr); 275 } 276 277 /* 278 * XXX: Note, the whole execve() is incredibly racey right now 279 * with regards to debugging and privilege/credential management. 280 * In particular, it's possible to race during exec() to attach 281 * debugging to a process that will gain privilege. 282 * 283 * This MUST be fixed prior to any release. 284 */ 285 286 /* 287 * Implement image setuid/setgid. 288 * 289 * Don't honor setuid/setgid if the filesystem prohibits it or if 290 * the process is being traced. 291 */ 292 oldcred = p->p_ucred; 293 newcred = NULL; 294 if ((((attr.va_mode & VSUID) && oldcred->cr_uid != attr.va_uid) || 295 ((attr.va_mode & VSGID) && oldcred->cr_gid != attr.va_gid)) && 296 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 297 (p->p_flag & P_TRACED) == 0) { 298 PROC_UNLOCK(p); 299 /* 300 * Turn off syscall tracing for set-id programs, except for 301 * root. 302 */ 303 if (p->p_tracep && suser_xxx(oldcred, NULL, PRISON_ROOT)) { 304 p->p_traceflag = 0; 305 vrele(p->p_tracep); 306 p->p_tracep = NULL; 307 } 308 /* 309 * Set the new credentials. 310 */ 311 newcred = crdup(oldcred); 312 if (attr.va_mode & VSUID) 313 change_euid(newcred, attr.va_uid); 314 if (attr.va_mode & VSGID) 315 change_egid(newcred, attr.va_gid); 316 setsugid(p); 317 setugidsafety(p); 318 } else { 319 if (oldcred->cr_uid == oldcred->cr_ruid && 320 oldcred->cr_gid == oldcred->cr_rgid) 321 p->p_flag &= ~P_SUGID; 322 PROC_UNLOCK(p); 323 } 324 325 /* 326 * Implement correct POSIX saved-id behavior. 327 * 328 * XXX: It's not clear that the existing behavior is 329 * POSIX-compliant. A number of sourses indicate that the saved 330 * uid/gid should only be updated if the new ruid is not equal to 331 * the old ruid, or the new euid is not equal to the old euid and 332 * the new euid is not equal to the old ruid. The FreeBSD code 333 * always updates the saved uid/gid. Also, this code uses the new 334 * (replaced) euid and egid as the source, which may or may not be 335 * the right ones to use. 336 */ 337 if (newcred == NULL) { 338 if (oldcred->cr_svuid != oldcred->cr_uid || 339 oldcred->cr_svgid != oldcred->cr_gid) { 340 newcred = crdup(oldcred); 341 change_svuid(newcred, newcred->cr_uid); 342 change_svgid(newcred, newcred->cr_gid); 343 } 344 } else { 345 change_svuid(newcred, newcred->cr_uid); 346 change_svgid(newcred, newcred->cr_gid); 347 } 348 349 if (newcred != NULL) { 350 PROC_LOCK(p); 351 p->p_ucred = newcred; 352 PROC_UNLOCK(p); 353 crfree(oldcred); 354 } 355 356 /* 357 * Store the vp for use in procfs 358 */ 359 if (p->p_textvp) /* release old reference */ 360 vrele(p->p_textvp); 361 VREF(ndp->ni_vp); 362 p->p_textvp = ndp->ni_vp; 363 364 /* 365 * notify others that we exec'd 366 */ 367 PROC_LOCK(p); 368 KNOTE(&p->p_klist, NOTE_EXEC); 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 /* Free any previous argument cache */ 387 if (p->p_args && --p->p_args->ar_ref == 0) 388 FREE(p->p_args, M_PARGS); 389 p->p_args = NULL; 390 391 /* Cache arguments if they fit inside our allowance */ 392 i = imgp->endargs - imgp->stringbase; 393 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 394 PROC_UNLOCK(p); 395 MALLOC(p->p_args, struct pargs *, sizeof(struct pargs) + i, 396 M_PARGS, M_WAITOK); 397 KASSERT(p->p_args != NULL, ("malloc of p_args failed")); 398 PROC_LOCK(p); 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 PROC_UNLOCK(p); 404 405 exec_fail_dealloc: 406 407 /* 408 * free various allocated resources 409 */ 410 if (imgp->firstpage) 411 exec_unmap_first_page(imgp); 412 413 if (imgp->stringbase != NULL) 414 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase, 415 ARG_MAX + PAGE_SIZE); 416 417 if (imgp->vp) { 418 NDFREE(ndp, NDF_ONLY_PNBUF); 419 vrele(imgp->vp); 420 } 421 422 if (error == 0) 423 return (0); 424 425 exec_fail: 426 if (imgp->vmspace_destroyed) { 427 /* sorry, no more process anymore. exit gracefully */ 428 exit1(p, W_EXITCODE(0, SIGABRT)); 429 /* NOT REACHED */ 430 return(0); 431 } else { 432 return(error); 433 } 434 } 435 436 int 437 exec_map_first_page(imgp) 438 struct image_params *imgp; 439 { 440 int rv, i; 441 int initial_pagein; 442 vm_page_t ma[VM_INITIAL_PAGEIN]; 443 vm_object_t object; 444 445 446 if (imgp->firstpage) { 447 exec_unmap_first_page(imgp); 448 } 449 450 VOP_GETVOBJECT(imgp->vp, &object); 451 mtx_lock(&vm_mtx); 452 453 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 454 455 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 456 initial_pagein = VM_INITIAL_PAGEIN; 457 if (initial_pagein > object->size) 458 initial_pagein = object->size; 459 for (i = 1; i < initial_pagein; i++) { 460 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 461 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy) 462 break; 463 if (ma[i]->valid) 464 break; 465 vm_page_busy(ma[i]); 466 } else { 467 ma[i] = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 468 if (ma[i] == NULL) 469 break; 470 } 471 } 472 initial_pagein = i; 473 474 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 475 ma[0] = vm_page_lookup(object, 0); 476 477 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || (ma[0]->valid == 0)) { 478 if (ma[0]) { 479 vm_page_protect(ma[0], VM_PROT_NONE); 480 vm_page_free(ma[0]); 481 } 482 mtx_unlock(&vm_mtx); 483 return EIO; 484 } 485 } 486 487 vm_page_wire(ma[0]); 488 vm_page_wakeup(ma[0]); 489 490 pmap_kenter((vm_offset_t) imgp->image_header, VM_PAGE_TO_PHYS(ma[0])); 491 imgp->firstpage = ma[0]; 492 493 mtx_unlock(&vm_mtx); 494 return 0; 495 } 496 497 void 498 exec_unmap_first_page(imgp) 499 struct image_params *imgp; 500 { 501 502 if (imgp->firstpage) { 503 mtx_lock(&vm_mtx); 504 pmap_kremove((vm_offset_t) imgp->image_header); 505 vm_page_unwire(imgp->firstpage, 1); 506 mtx_unlock(&vm_mtx); 507 imgp->firstpage = NULL; 508 } 509 } 510 511 /* 512 * Destroy old address space, and allocate a new stack 513 * The new stack is only SGROWSIZ large because it is grown 514 * automatically in trap.c. 515 */ 516 int 517 exec_new_vmspace(imgp) 518 struct image_params *imgp; 519 { 520 int error; 521 struct vmspace *vmspace = imgp->proc->p_vmspace; 522 caddr_t stack_addr = (caddr_t) (USRSTACK - MAXSSIZ); 523 vm_map_t map = &vmspace->vm_map; 524 525 mtx_assert(&vm_mtx, MA_OWNED); 526 imgp->vmspace_destroyed = 1; 527 528 /* 529 * Blow away entire process VM, if address space not shared, 530 * otherwise, create a new VM space so that other threads are 531 * not disrupted 532 */ 533 if (vmspace->vm_refcnt == 1) { 534 if (vmspace->vm_shm) 535 shmexit(imgp->proc); 536 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); 537 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); 538 } else { 539 vmspace_exec(imgp->proc); 540 vmspace = imgp->proc->p_vmspace; 541 map = &vmspace->vm_map; 542 } 543 544 /* Allocate a new stack */ 545 error = vm_map_stack (&vmspace->vm_map, (vm_offset_t)stack_addr, 546 (vm_size_t)MAXSSIZ, VM_PROT_ALL, VM_PROT_ALL, 0); 547 if (error) 548 return (error); 549 550 #ifdef __ia64__ 551 { 552 /* 553 * Allocate backing store. We really need something 554 * similar to vm_map_stack which can allow the backing 555 * store to grow upwards. This will do for now. 556 */ 557 vm_offset_t bsaddr; 558 bsaddr = USRSTACK - 2*MAXSSIZ; 559 error = vm_map_find(&vmspace->vm_map, 0, 0, &bsaddr, 560 4*PAGE_SIZE, 0, 561 VM_PROT_ALL, VM_PROT_ALL, 0); 562 imgp->proc->p_md.md_bspstore = bsaddr; 563 } 564 #endif 565 566 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 567 * VM_STACK case, but they are still used to monitor the size of the 568 * process stack so we can check the stack rlimit. 569 */ 570 vmspace->vm_ssize = SGROWSIZ >> PAGE_SHIFT; 571 vmspace->vm_maxsaddr = (char *)USRSTACK - MAXSSIZ; 572 573 return(0); 574 } 575 576 /* 577 * Copy out argument and environment strings from the old process 578 * address space into the temporary string buffer. 579 */ 580 int 581 exec_extract_strings(imgp) 582 struct image_params *imgp; 583 { 584 char **argv, **envv; 585 char *argp, *envp; 586 int error; 587 size_t length; 588 589 /* 590 * extract arguments first 591 */ 592 593 argv = imgp->uap->argv; 594 595 if (argv) { 596 argp = (caddr_t) (intptr_t) fuword(argv); 597 if (argp == (caddr_t) -1) 598 return (EFAULT); 599 if (argp) 600 argv++; 601 if (imgp->argv0) 602 argp = imgp->argv0; 603 if (argp) { 604 do { 605 if (argp == (caddr_t) -1) 606 return (EFAULT); 607 if ((error = copyinstr(argp, imgp->stringp, 608 imgp->stringspace, &length))) { 609 if (error == ENAMETOOLONG) 610 return(E2BIG); 611 return (error); 612 } 613 imgp->stringspace -= length; 614 imgp->stringp += length; 615 imgp->argc++; 616 } while ((argp = (caddr_t) (intptr_t) fuword(argv++))); 617 } 618 } 619 620 imgp->endargs = imgp->stringp; 621 622 /* 623 * extract environment strings 624 */ 625 626 envv = imgp->uap->envv; 627 628 if (envv) { 629 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 630 if (envp == (caddr_t) -1) 631 return (EFAULT); 632 if ((error = copyinstr(envp, imgp->stringp, 633 imgp->stringspace, &length))) { 634 if (error == ENAMETOOLONG) 635 return(E2BIG); 636 return (error); 637 } 638 imgp->stringspace -= length; 639 imgp->stringp += length; 640 imgp->envc++; 641 } 642 } 643 644 return (0); 645 } 646 647 /* 648 * Copy strings out to the new process address space, constructing 649 * new arg and env vector tables. Return a pointer to the base 650 * so that it can be used as the initial stack pointer. 651 */ 652 register_t * 653 exec_copyout_strings(imgp) 654 struct image_params *imgp; 655 { 656 int argc, envc; 657 char **vectp; 658 char *stringp, *destp; 659 register_t *stack_base; 660 struct ps_strings *arginfo; 661 int szsigcode; 662 663 /* 664 * Calculate string base and vector table pointers. 665 * Also deal with signal trampoline code for this exec type. 666 */ 667 arginfo = (struct ps_strings *)PS_STRINGS; 668 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 669 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 670 roundup((ARG_MAX - imgp->stringspace), sizeof(char *)); 671 672 /* 673 * install sigcode 674 */ 675 if (szsigcode) 676 copyout(imgp->proc->p_sysent->sv_sigcode, 677 ((caddr_t)arginfo - szsigcode), szsigcode); 678 679 /* 680 * If we have a valid auxargs ptr, prepare some room 681 * on the stack. 682 */ 683 if (imgp->auxargs) { 684 /* 685 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 686 * lower compatibility. 687 */ 688 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size 689 : (AT_COUNT * 2); 690 /* 691 * The '+ 2' is for the null pointers at the end of each of 692 * the arg and env vector sets,and imgp->auxarg_size is room 693 * for argument of Runtime loader. 694 */ 695 vectp = (char **) (destp - (imgp->argc + imgp->envc + 2 + 696 imgp->auxarg_size) * sizeof(char *)); 697 698 } else 699 /* 700 * The '+ 2' is for the null pointers at the end of each of 701 * the arg and env vector sets 702 */ 703 vectp = (char **) 704 (destp - (imgp->argc + imgp->envc + 2) * sizeof(char *)); 705 706 /* 707 * vectp also becomes our initial stack base 708 */ 709 stack_base = (register_t *)vectp; 710 711 stringp = imgp->stringbase; 712 argc = imgp->argc; 713 envc = imgp->envc; 714 715 /* 716 * Copy out strings - arguments and environment. 717 */ 718 copyout(stringp, destp, ARG_MAX - imgp->stringspace); 719 720 /* 721 * Fill in "ps_strings" struct for ps, w, etc. 722 */ 723 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 724 suword(&arginfo->ps_nargvstr, argc); 725 726 /* 727 * Fill in argument portion of vector table. 728 */ 729 for (; argc > 0; --argc) { 730 suword(vectp++, (long)(intptr_t)destp); 731 while (*stringp++ != 0) 732 destp++; 733 destp++; 734 } 735 736 /* a null vector table pointer separates the argp's from the envp's */ 737 suword(vectp++, 0); 738 739 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 740 suword(&arginfo->ps_nenvstr, envc); 741 742 /* 743 * Fill in environment portion of vector table. 744 */ 745 for (; envc > 0; --envc) { 746 suword(vectp++, (long)(intptr_t)destp); 747 while (*stringp++ != 0) 748 destp++; 749 destp++; 750 } 751 752 /* end of vector table is a null pointer */ 753 suword(vectp, 0); 754 755 return (stack_base); 756 } 757 758 /* 759 * Check permissions of file to execute. 760 * Called with imgp->vp locked. 761 * Return 0 for success or error code on failure. 762 */ 763 int 764 exec_check_permissions(imgp) 765 struct image_params *imgp; 766 { 767 struct proc *p = imgp->proc; 768 struct vnode *vp = imgp->vp; 769 struct vattr *attr = imgp->attr; 770 int error; 771 772 /* Get file attributes */ 773 error = VOP_GETATTR(vp, attr, p->p_ucred, p); 774 if (error) 775 return (error); 776 777 /* 778 * 1) Check if file execution is disabled for the filesystem that this 779 * file resides on. 780 * 2) Insure that at least one execute bit is on - otherwise root 781 * will always succeed, and we don't want to happen unless the 782 * file really is executable. 783 * 3) Insure that the file is a regular file. 784 */ 785 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 786 ((attr->va_mode & 0111) == 0) || 787 (attr->va_type != VREG)) { 788 return (EACCES); 789 } 790 791 /* 792 * Zero length files can't be exec'd 793 */ 794 if (attr->va_size == 0) 795 return (ENOEXEC); 796 797 /* 798 * Check for execute permission to file based on current credentials. 799 */ 800 error = VOP_ACCESS(vp, VEXEC, p->p_ucred, p); 801 if (error) 802 return (error); 803 804 /* 805 * Check number of open-for-writes on the file and deny execution 806 * if there are any. 807 */ 808 if (vp->v_writecount) 809 return (ETXTBSY); 810 811 /* 812 * Call filesystem specific open routine (which does nothing in the 813 * general case). 814 */ 815 error = VOP_OPEN(vp, FREAD, p->p_ucred, p); 816 if (error) 817 return (error); 818 819 return (0); 820 } 821 822 /* 823 * Exec handler registration 824 */ 825 int 826 exec_register(execsw_arg) 827 const struct execsw *execsw_arg; 828 { 829 const struct execsw **es, **xs, **newexecsw; 830 int count = 2; /* New slot and trailing NULL */ 831 832 if (execsw) 833 for (es = execsw; *es; es++) 834 count++; 835 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 836 if (newexecsw == NULL) 837 return ENOMEM; 838 xs = newexecsw; 839 if (execsw) 840 for (es = execsw; *es; es++) 841 *xs++ = *es; 842 *xs++ = execsw_arg; 843 *xs = NULL; 844 if (execsw) 845 free(execsw, M_TEMP); 846 execsw = newexecsw; 847 return 0; 848 } 849 850 int 851 exec_unregister(execsw_arg) 852 const struct execsw *execsw_arg; 853 { 854 const struct execsw **es, **xs, **newexecsw; 855 int count = 1; 856 857 if (execsw == NULL) 858 panic("unregister with no handlers left?\n"); 859 860 for (es = execsw; *es; es++) { 861 if (*es == execsw_arg) 862 break; 863 } 864 if (*es == NULL) 865 return ENOENT; 866 for (es = execsw; *es; es++) 867 if (*es != execsw_arg) 868 count++; 869 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 870 if (newexecsw == NULL) 871 return ENOMEM; 872 xs = newexecsw; 873 for (es = execsw; *es; es++) 874 if (*es != execsw_arg) 875 *xs++ = *es; 876 *xs = NULL; 877 if (execsw) 878 free(execsw, M_TEMP); 879 execsw = newexecsw; 880 return 0; 881 } 882