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 1.12 2003/09/23 05:03:51 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 (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, NAMEI_LOOKUP, CNP_LOCKLEAF | CNP_FOLLOW | CNP_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, NAMEI_LOOKUP, 222 CNP_LOCKLEAF | CNP_FOLLOW | CNP_SAVENAME, 223 UIO_SYSSPACE, imgp->interpreter_name, td); 224 goto interpret; 225 } 226 227 /* 228 * Copy out strings (args and env) and initialize stack base 229 */ 230 stack_base = exec_copyout_strings(imgp); 231 p->p_vmspace->vm_minsaddr = (char *)stack_base; 232 233 /* 234 * If custom stack fixup routine present for this process 235 * let it do the stack setup. 236 * Else stuff argument count as first item on stack 237 */ 238 if (p->p_sysent->sv_fixup) 239 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 240 else 241 suword(--stack_base, imgp->argc); 242 243 /* 244 * For security and other reasons, the file descriptor table cannot 245 * be shared after an exec. 246 */ 247 if (p->p_fd->fd_refcnt > 1) { 248 struct filedesc *tmp; 249 250 tmp = fdcopy(p); 251 fdfree(p); 252 p->p_fd = tmp; 253 } 254 255 /* 256 * For security and other reasons, signal handlers cannot 257 * be shared after an exec. The new proces gets a copy of the old 258 * handlers. In execsigs(), the new process will have its signals 259 * reset. 260 */ 261 if (p->p_procsig->ps_refcnt > 1) { 262 struct procsig *newprocsig; 263 264 MALLOC(newprocsig, struct procsig *, sizeof(struct procsig), 265 M_SUBPROC, M_WAITOK); 266 bcopy(p->p_procsig, newprocsig, sizeof(*newprocsig)); 267 p->p_procsig->ps_refcnt--; 268 p->p_procsig = newprocsig; 269 p->p_procsig->ps_refcnt = 1; 270 if (p->p_sigacts == &p->p_addr->u_sigacts) 271 panic("shared procsig but private sigacts?"); 272 273 p->p_addr->u_sigacts = *p->p_sigacts; 274 p->p_sigacts = &p->p_addr->u_sigacts; 275 } 276 277 /* Stop profiling */ 278 stopprofclock(p); 279 280 /* close files on exec */ 281 fdcloseexec(p); 282 283 /* reset caught signals */ 284 execsigs(p); 285 286 /* name this process - nameiexec(p, ndp) */ 287 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 288 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 289 p->p_comm[len] = 0; 290 291 /* 292 * mark as execed, wakeup the process that vforked (if any) and tell 293 * it that it now has its own resources back 294 */ 295 p->p_flag |= P_EXEC; 296 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 297 p->p_flag &= ~P_PPWAIT; 298 wakeup((caddr_t)p->p_pptr); 299 } 300 301 /* 302 * Implement image setuid/setgid. 303 * 304 * Don't honor setuid/setgid if the filesystem prohibits it or if 305 * the process is being traced. 306 */ 307 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 308 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 309 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 310 (p->p_flag & P_TRACED) == 0) { 311 /* 312 * Turn off syscall tracing for set-id programs, except for 313 * root. Record any set-id flags first to make sure that 314 * we do not regain any tracing during a possible block. 315 */ 316 setsugid(); 317 if (p->p_tracep && suser(td)) { 318 struct vnode *vtmp; 319 320 if ((vtmp = p->p_tracep) != NULL) { 321 p->p_tracep = NULL; 322 p->p_traceflag = 0; 323 vrele(vtmp); 324 } 325 } 326 /* Close any file descriptors 0..2 that reference procfs */ 327 setugidsafety(p); 328 /* Make sure file descriptors 0..2 are in use. */ 329 error = fdcheckstd(p); 330 if (error != 0) 331 goto exec_fail_dealloc; 332 /* 333 * Set the new credentials. 334 */ 335 cratom(&p->p_ucred); 336 if (attr.va_mode & VSUID) 337 change_euid(attr.va_uid); 338 if (attr.va_mode & VSGID) 339 p->p_ucred->cr_gid = attr.va_gid; 340 } else { 341 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && 342 p->p_ucred->cr_gid == p->p_ucred->cr_rgid) 343 p->p_flag &= ~P_SUGID; 344 } 345 346 /* 347 * Implement correct POSIX saved-id behavior. 348 */ 349 if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || 350 p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { 351 cratom(&p->p_ucred); 352 p->p_ucred->cr_svuid = p->p_ucred->cr_uid; 353 p->p_ucred->cr_svgid = p->p_ucred->cr_gid; 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, and clear the P_INEXEC flag 366 * as we're now a bona fide freshly-execed process. 367 */ 368 KNOTE(&p->p_klist, NOTE_EXEC); 369 p->p_flag &= ~P_INEXEC; 370 371 /* 372 * If tracing the process, trap to debugger so breakpoints 373 * can be set before the program executes. 374 */ 375 STOPEVENT(p, S_EXEC, 0); 376 377 if (p->p_flag & P_TRACED) 378 psignal(p, SIGTRAP); 379 380 /* clear "fork but no exec" flag, as we _are_ execing */ 381 p->p_acflag &= ~AFORK; 382 383 /* Set values passed into the program in registers. */ 384 setregs(p, imgp->entry_addr, (u_long)(uintptr_t)stack_base, 385 imgp->ps_strings); 386 387 /* 388 * The syscall result is returned in registers to the new program. 389 * Linux will register %edx as an atexit function and we must be 390 * sure to set it to 0. XXX 391 */ 392 uap->sysmsg_result64 = 0; 393 394 /* Free any previous argument cache */ 395 if (p->p_args && --p->p_args->ar_ref == 0) 396 FREE(p->p_args, M_PARGS); 397 p->p_args = NULL; 398 399 /* Cache arguments if they fit inside our allowance */ 400 i = imgp->endargs - imgp->stringbase; 401 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 402 MALLOC(p->p_args, struct pargs *, sizeof(struct pargs) + i, 403 M_PARGS, M_WAITOK); 404 p->p_args->ar_ref = 1; 405 p->p_args->ar_length = i; 406 bcopy(imgp->stringbase, p->p_args->ar_args, i); 407 } 408 409 exec_fail_dealloc: 410 411 /* 412 * free various allocated resources 413 */ 414 if (imgp->firstpage) 415 exec_unmap_first_page(imgp); 416 417 if (imgp->stringbase != NULL) 418 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase, 419 ARG_MAX + PAGE_SIZE); 420 421 if (imgp->vp) { 422 NDFREE(ndp, NDF_ONLY_PNBUF); 423 vrele(imgp->vp); 424 } 425 426 if (error == 0) 427 return (0); 428 429 exec_fail: 430 /* we're done here, clear P_INEXEC */ 431 p->p_flag &= ~P_INEXEC; 432 if (imgp->vmspace_destroyed) { 433 /* sorry, no more process anymore. exit gracefully */ 434 exit1(W_EXITCODE(0, SIGABRT)); 435 /* NOT REACHED */ 436 return(0); 437 } else { 438 return(error); 439 } 440 } 441 442 int 443 exec_map_first_page(struct image_params *imgp) 444 { 445 int s, rv, i; 446 int initial_pagein; 447 vm_page_t ma[VM_INITIAL_PAGEIN]; 448 vm_object_t object; 449 450 451 if (imgp->firstpage) { 452 exec_unmap_first_page(imgp); 453 } 454 455 VOP_GETVOBJECT(imgp->vp, &object); 456 s = splvm(); 457 458 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 459 460 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 461 initial_pagein = VM_INITIAL_PAGEIN; 462 if (initial_pagein > object->size) 463 initial_pagein = object->size; 464 for (i = 1; i < initial_pagein; i++) { 465 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 466 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy) 467 break; 468 if (ma[i]->valid) 469 break; 470 vm_page_busy(ma[i]); 471 } else { 472 ma[i] = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 473 if (ma[i] == NULL) 474 break; 475 } 476 } 477 initial_pagein = i; 478 479 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 480 ma[0] = vm_page_lookup(object, 0); 481 482 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || (ma[0]->valid == 0)) { 483 if (ma[0]) { 484 vm_page_protect(ma[0], VM_PROT_NONE); 485 vm_page_free(ma[0]); 486 } 487 splx(s); 488 return EIO; 489 } 490 } 491 492 vm_page_wire(ma[0]); 493 vm_page_wakeup(ma[0]); 494 splx(s); 495 496 pmap_kenter((vm_offset_t) imgp->image_header, VM_PAGE_TO_PHYS(ma[0])); 497 imgp->firstpage = ma[0]; 498 499 return 0; 500 } 501 502 void 503 exec_unmap_first_page(imgp) 504 struct image_params *imgp; 505 { 506 if (imgp->firstpage) { 507 pmap_kremove((vm_offset_t) imgp->image_header); 508 vm_page_unwire(imgp->firstpage, 1); 509 imgp->firstpage = NULL; 510 } 511 } 512 513 /* 514 * Destroy old address space, and allocate a new stack 515 * The new stack is only SGROWSIZ large because it is grown 516 * automatically in trap.c. 517 */ 518 int 519 exec_new_vmspace(imgp) 520 struct image_params *imgp; 521 { 522 int error; 523 struct vmspace *vmspace = imgp->proc->p_vmspace; 524 vm_offset_t stack_addr = USRSTACK - maxssiz; 525 vm_map_t map = &vmspace->vm_map; 526 527 imgp->vmspace_destroyed = 1; 528 529 /* 530 * Prevent a pending AIO from modifying the new address space. 531 */ 532 aio_proc_rundown(imgp->proc); 533 534 /* 535 * Blow away entire process VM, if address space not shared, 536 * otherwise, create a new VM space so that other threads are 537 * not disrupted 538 */ 539 if (vmspace->vm_refcnt == 1) { 540 shmexit(vmspace); 541 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); 542 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); 543 } else { 544 vmspace_exec(imgp->proc); 545 vmspace = imgp->proc->p_vmspace; 546 map = &vmspace->vm_map; 547 } 548 549 /* Allocate a new stack */ 550 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 551 VM_PROT_ALL, VM_PROT_ALL, 0); 552 if (error) 553 return (error); 554 555 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 556 * VM_STACK case, but they are still used to monitor the size of the 557 * process stack so we can check the stack rlimit. 558 */ 559 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 560 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 561 562 return(0); 563 } 564 565 /* 566 * Copy out argument and environment strings from the old process 567 * address space into the temporary string buffer. 568 */ 569 int 570 exec_extract_strings(imgp) 571 struct image_params *imgp; 572 { 573 char **argv, **envv; 574 char *argp, *envp; 575 int error; 576 size_t length; 577 578 /* 579 * extract arguments first 580 */ 581 582 argv = imgp->uap->argv; 583 584 if (argv) { 585 argp = (caddr_t) (intptr_t) fuword(argv); 586 if (argp == (caddr_t) -1) 587 return (EFAULT); 588 if (argp) 589 argv++; 590 if (imgp->argv0) 591 argp = imgp->argv0; 592 if (argp) { 593 do { 594 if (argp == (caddr_t) -1) 595 return (EFAULT); 596 if ((error = copyinstr(argp, imgp->stringp, 597 imgp->stringspace, &length))) { 598 if (error == ENAMETOOLONG) 599 return(E2BIG); 600 return (error); 601 } 602 imgp->stringspace -= length; 603 imgp->stringp += length; 604 imgp->argc++; 605 } while ((argp = (caddr_t) (intptr_t) fuword(argv++))); 606 } 607 } 608 609 imgp->endargs = imgp->stringp; 610 611 /* 612 * extract environment strings 613 */ 614 615 envv = imgp->uap->envv; 616 617 if (envv) { 618 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 619 if (envp == (caddr_t) -1) 620 return (EFAULT); 621 if ((error = copyinstr(envp, imgp->stringp, 622 imgp->stringspace, &length))) { 623 if (error == ENAMETOOLONG) 624 return(E2BIG); 625 return (error); 626 } 627 imgp->stringspace -= length; 628 imgp->stringp += length; 629 imgp->envc++; 630 } 631 } 632 633 return (0); 634 } 635 636 /* 637 * Copy strings out to the new process address space, constructing 638 * new arg and env vector tables. Return a pointer to the base 639 * so that it can be used as the initial stack pointer. 640 */ 641 register_t * 642 exec_copyout_strings(imgp) 643 struct image_params *imgp; 644 { 645 int argc, envc; 646 char **vectp; 647 char *stringp, *destp; 648 register_t *stack_base; 649 struct ps_strings *arginfo; 650 int szsigcode; 651 652 /* 653 * Calculate string base and vector table pointers. 654 * Also deal with signal trampoline code for this exec type. 655 */ 656 arginfo = (struct ps_strings *)PS_STRINGS; 657 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 658 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 659 roundup((ARG_MAX - imgp->stringspace), sizeof(char *)); 660 661 /* 662 * install sigcode 663 */ 664 if (szsigcode) 665 copyout(imgp->proc->p_sysent->sv_sigcode, 666 ((caddr_t)arginfo - szsigcode), szsigcode); 667 668 /* 669 * If we have a valid auxargs ptr, prepare some room 670 * on the stack. 671 */ 672 if (imgp->auxargs) 673 /* 674 * The '+ 2' is for the null pointers at the end of each of the 675 * arg and env vector sets, and 'AT_COUNT*2' is room for the 676 * ELF Auxargs data. 677 */ 678 vectp = (char **)(destp - (imgp->argc + imgp->envc + 2 + 679 AT_COUNT*2) * sizeof(char*)); 680 else 681 /* 682 * The '+ 2' is for the null pointers at the end of each of the 683 * arg and env vector sets 684 */ 685 vectp = (char **) 686 (destp - (imgp->argc + imgp->envc + 2) * sizeof(char*)); 687 688 /* 689 * vectp also becomes our initial stack base 690 */ 691 stack_base = (register_t *)vectp; 692 693 stringp = imgp->stringbase; 694 argc = imgp->argc; 695 envc = imgp->envc; 696 697 /* 698 * Copy out strings - arguments and environment. 699 */ 700 copyout(stringp, destp, ARG_MAX - imgp->stringspace); 701 702 /* 703 * Fill in "ps_strings" struct for ps, w, etc. 704 */ 705 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 706 suword(&arginfo->ps_nargvstr, argc); 707 708 /* 709 * Fill in argument portion of vector table. 710 */ 711 for (; argc > 0; --argc) { 712 suword(vectp++, (long)(intptr_t)destp); 713 while (*stringp++ != 0) 714 destp++; 715 destp++; 716 } 717 718 /* a null vector table pointer seperates the argp's from the envp's */ 719 suword(vectp++, 0); 720 721 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 722 suword(&arginfo->ps_nenvstr, envc); 723 724 /* 725 * Fill in environment portion of vector table. 726 */ 727 for (; envc > 0; --envc) { 728 suword(vectp++, (long)(intptr_t)destp); 729 while (*stringp++ != 0) 730 destp++; 731 destp++; 732 } 733 734 /* end of vector table is a null pointer */ 735 suword(vectp, 0); 736 737 return (stack_base); 738 } 739 740 /* 741 * Check permissions of file to execute. 742 * Return 0 for success or error code on failure. 743 */ 744 int 745 exec_check_permissions(imgp) 746 struct image_params *imgp; 747 { 748 struct proc *p = imgp->proc; 749 struct vnode *vp = imgp->vp; 750 struct vattr *attr = imgp->attr; 751 struct thread *td = p->p_thread; 752 int error; 753 754 /* Get file attributes */ 755 error = VOP_GETATTR(vp, attr, td); 756 if (error) 757 return (error); 758 759 /* 760 * 1) Check if file execution is disabled for the filesystem that this 761 * file resides on. 762 * 2) Insure that at least one execute bit is on - otherwise root 763 * will always succeed, and we don't want to happen unless the 764 * file really is executable. 765 * 3) Insure that the file is a regular file. 766 */ 767 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 768 ((attr->va_mode & 0111) == 0) || 769 (attr->va_type != VREG)) { 770 return (EACCES); 771 } 772 773 /* 774 * Zero length files can't be exec'd 775 */ 776 if (attr->va_size == 0) 777 return (ENOEXEC); 778 779 /* 780 * Check for execute permission to file based on current credentials. 781 */ 782 error = VOP_ACCESS(vp, VEXEC, p->p_ucred, td); 783 if (error) 784 return (error); 785 786 /* 787 * Check number of open-for-writes on the file and deny execution 788 * if there are any. 789 */ 790 if (vp->v_writecount) 791 return (ETXTBSY); 792 793 /* 794 * Call filesystem specific open routine (which does nothing in the 795 * general case). 796 */ 797 error = VOP_OPEN(vp, FREAD, p->p_ucred, td); 798 if (error) 799 return (error); 800 801 return (0); 802 } 803 804 /* 805 * Exec handler registration 806 */ 807 int 808 exec_register(execsw_arg) 809 const struct execsw *execsw_arg; 810 { 811 const struct execsw **es, **xs, **newexecsw; 812 int count = 2; /* New slot and trailing NULL */ 813 814 if (execsw) 815 for (es = execsw; *es; es++) 816 count++; 817 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 818 if (newexecsw == NULL) 819 return ENOMEM; 820 xs = newexecsw; 821 if (execsw) 822 for (es = execsw; *es; es++) 823 *xs++ = *es; 824 *xs++ = execsw_arg; 825 *xs = NULL; 826 if (execsw) 827 free(execsw, M_TEMP); 828 execsw = newexecsw; 829 return 0; 830 } 831 832 int 833 exec_unregister(execsw_arg) 834 const struct execsw *execsw_arg; 835 { 836 const struct execsw **es, **xs, **newexecsw; 837 int count = 1; 838 839 if (execsw == NULL) 840 panic("unregister with no handlers left?\n"); 841 842 for (es = execsw; *es; es++) { 843 if (*es == execsw_arg) 844 break; 845 } 846 if (*es == NULL) 847 return ENOENT; 848 for (es = execsw; *es; es++) 849 if (*es != execsw_arg) 850 count++; 851 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 852 if (newexecsw == NULL) 853 return ENOMEM; 854 xs = newexecsw; 855 for (es = execsw; *es; es++) 856 if (*es != execsw_arg) 857 *xs++ = *es; 858 *xs = NULL; 859 if (execsw) 860 free(execsw, M_TEMP); 861 execsw = newexecsw; 862 return 0; 863 } 864