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 1.20 2004/03/01 06:33:17 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/kern_syscall.h> 42 #include <sys/wait.h> 43 #include <sys/malloc.h> 44 #include <sys/proc.h> 45 #include <sys/signalvar.h> 46 #include <sys/pioctl.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 #include <sys/aio.h> 53 54 #include <vm/vm.h> 55 #include <vm/vm_param.h> 56 #include <sys/lock.h> 57 #include <vm/pmap.h> 58 #include <vm/vm_page.h> 59 #include <vm/vm_map.h> 60 #include <vm/vm_kern.h> 61 #include <vm/vm_extern.h> 62 #include <vm/vm_object.h> 63 #include <vm/vm_pager.h> 64 65 #include <sys/user.h> 66 #include <machine/reg.h> 67 68 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 69 70 static register_t *exec_copyout_strings (struct image_params *); 71 72 /* XXX This should be vm_size_t. */ 73 static u_long ps_strings = PS_STRINGS; 74 SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, ""); 75 76 /* XXX This should be vm_size_t. */ 77 static u_long usrstack = USRSTACK; 78 SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, ""); 79 80 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 81 SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 82 &ps_arg_cache_limit, 0, ""); 83 84 int ps_argsopen = 1; 85 SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, ""); 86 87 void print_execve_args(struct image_args *args); 88 int debug_execve_args = 0; 89 SYSCTL_INT(_kern, OID_AUTO, debug_execve_args, CTLFLAG_RW, &debug_execve_args, 90 0, ""); 91 92 void 93 print_execve_args(struct image_args *args) 94 { 95 char *cp; 96 int ndx; 97 98 cp = args->begin_argv; 99 for (ndx = 0; ndx < args->argc; ndx++) { 100 printf("\targv[%d]: %s\n", ndx, cp); 101 while (*cp++ != '\0'); 102 } 103 for (ndx = 0; ndx < args->envc; ndx++) { 104 printf("\tenvv[%d]: %s\n", ndx, cp); 105 while (*cp++ != '\0'); 106 } 107 } 108 109 /* 110 * Each of the items is a pointer to a `const struct execsw', hence the 111 * double pointer here. 112 */ 113 static const struct execsw **execsw; 114 115 int 116 kern_execve(struct nameidata *ndp, struct image_args *args) 117 { 118 struct thread *td = curthread; 119 struct proc *p = td->td_proc; 120 register_t *stack_base; 121 int error, len, i; 122 struct image_params image_params, *imgp; 123 struct vattr attr; 124 int (*img_first) (struct image_params *); 125 126 if (debug_execve_args) { 127 printf("%s()\n", __func__); 128 print_execve_args(args); 129 } 130 131 KKASSERT(p); 132 imgp = &image_params; 133 134 /* 135 * Lock the process and set the P_INEXEC flag to indicate that 136 * it should be left alone until we're done here. This is 137 * necessary to avoid race conditions - e.g. in ptrace() - 138 * that might allow a local user to illicitly obtain elevated 139 * privileges. 140 */ 141 p->p_flag |= P_INEXEC; 142 143 /* 144 * Initialize part of the common data 145 */ 146 imgp->proc = p; 147 imgp->args = args; 148 imgp->attr = &attr; 149 imgp->entry_addr = 0; 150 imgp->resident = 0; 151 imgp->vmspace_destroyed = 0; 152 imgp->interpreted = 0; 153 imgp->interpreter_name[0] = 0; 154 imgp->auxargs = NULL; 155 imgp->vp = NULL; 156 imgp->firstpage = NULL; 157 imgp->ps_strings = 0; 158 159 /* 160 * Allocate temporary demand zeroed space for argument and 161 * environment strings 162 */ 163 imgp->image_header = (char *)kmem_alloc_wait(exec_map, PAGE_SIZE); 164 if (imgp->image_header == NULL) { 165 error = ENOMEM; 166 goto exec_fail; 167 } 168 169 interpret: 170 171 /* 172 * Translate the file name. namei() returns a vnode pointer 173 * in ni_vp amoung other things. 174 */ 175 error = namei(ndp); 176 if (error) { 177 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->image_header, 178 PAGE_SIZE); 179 goto exec_fail; 180 } 181 182 imgp->vp = ndp->ni_vp; 183 184 /* 185 * Check file permissions (also 'opens' file) 186 */ 187 error = exec_check_permissions(imgp); 188 if (error) { 189 VOP_UNLOCK(imgp->vp, NULL, 0, td); 190 goto exec_fail_dealloc; 191 } 192 193 error = exec_map_first_page(imgp); 194 VOP_UNLOCK(imgp->vp, NULL, 0, td); 195 if (error) 196 goto exec_fail_dealloc; 197 198 if (debug_execve_args && imgp->interpreted) { 199 printf(" target is interpreted -- recursive pass\n"); 200 printf(" interpreter: %s\n", imgp->interpreter_name); 201 print_execve_args(args); 202 } 203 204 /* 205 * If the current process has a special image activator it 206 * wants to try first, call it. For example, emulating shell 207 * scripts differently. 208 */ 209 error = -1; 210 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 211 error = img_first(imgp); 212 213 /* 214 * If the vnode has a registered vmspace, exec the vmspace 215 */ 216 if (error == -1 && imgp->vp->v_resident) { 217 error = exec_resident_imgact(imgp); 218 } 219 220 /* 221 * Loop through the list of image activators, calling each one. 222 * An activator returns -1 if there is no match, 0 on success, 223 * and an error otherwise. 224 */ 225 for (i = 0; error == -1 && execsw[i]; ++i) { 226 if (execsw[i]->ex_imgact == NULL || 227 execsw[i]->ex_imgact == img_first) { 228 continue; 229 } 230 error = (*execsw[i]->ex_imgact)(imgp); 231 } 232 233 if (error) { 234 if (error == -1) 235 error = ENOEXEC; 236 goto exec_fail_dealloc; 237 } 238 239 /* 240 * Special interpreter operation, cleanup and loop up to try to 241 * activate the interpreter. 242 */ 243 if (imgp->interpreted) { 244 exec_unmap_first_page(imgp); 245 /* free name buffer and old vnode */ 246 NDFREE(ndp, NDF_ONLY_PNBUF); 247 vrele(ndp->ni_vp); 248 /* set new name to that of the interpreter */ 249 NDINIT(ndp, NAMEI_LOOKUP, 250 CNP_LOCKLEAF | CNP_FOLLOW | CNP_SAVENAME, 251 UIO_SYSSPACE, imgp->interpreter_name, td); 252 goto interpret; 253 } 254 255 /* 256 * Copy out strings (args and env) and initialize stack base 257 */ 258 stack_base = exec_copyout_strings(imgp); 259 p->p_vmspace->vm_minsaddr = (char *)stack_base; 260 261 /* 262 * If custom stack fixup routine present for this process 263 * let it do the stack setup. If we are running a resident 264 * image there is no auxinfo or other image activator context 265 * so don't try to add fixups to the stack. 266 * 267 * Else stuff argument count as first item on stack 268 */ 269 if (p->p_sysent->sv_fixup && imgp->resident == 0) 270 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 271 else 272 suword(--stack_base, imgp->args->argc); 273 274 /* 275 * For security and other reasons, the file descriptor table cannot 276 * be shared after an exec. 277 */ 278 if (p->p_fd->fd_refcnt > 1) { 279 struct filedesc *tmp; 280 281 tmp = fdcopy(p); 282 fdfree(p); 283 p->p_fd = tmp; 284 } 285 286 /* 287 * For security and other reasons, signal handlers cannot 288 * be shared after an exec. The new proces gets a copy of the old 289 * handlers. In execsigs(), the new process will have its signals 290 * reset. 291 */ 292 if (p->p_procsig->ps_refcnt > 1) { 293 struct procsig *newprocsig; 294 295 MALLOC(newprocsig, struct procsig *, sizeof(struct procsig), 296 M_SUBPROC, M_WAITOK); 297 bcopy(p->p_procsig, newprocsig, sizeof(*newprocsig)); 298 p->p_procsig->ps_refcnt--; 299 p->p_procsig = newprocsig; 300 p->p_procsig->ps_refcnt = 1; 301 if (p->p_sigacts == &p->p_addr->u_sigacts) 302 panic("shared procsig but private sigacts?"); 303 304 p->p_addr->u_sigacts = *p->p_sigacts; 305 p->p_sigacts = &p->p_addr->u_sigacts; 306 } 307 308 /* Stop profiling */ 309 stopprofclock(p); 310 311 /* close files on exec */ 312 fdcloseexec(p); 313 314 /* reset caught signals */ 315 execsigs(p); 316 317 /* name this process - nameiexec(p, ndp) */ 318 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 319 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 320 p->p_comm[len] = 0; 321 322 /* 323 * mark as execed, wakeup the process that vforked (if any) and tell 324 * it that it now has its own resources back 325 */ 326 p->p_flag |= P_EXEC; 327 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 328 p->p_flag &= ~P_PPWAIT; 329 wakeup((caddr_t)p->p_pptr); 330 } 331 332 /* 333 * Implement image setuid/setgid. 334 * 335 * Don't honor setuid/setgid if the filesystem prohibits it or if 336 * the process is being traced. 337 */ 338 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 339 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 340 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 341 (p->p_flag & P_TRACED) == 0) { 342 /* 343 * Turn off syscall tracing for set-id programs, except for 344 * root. Record any set-id flags first to make sure that 345 * we do not regain any tracing during a possible block. 346 */ 347 setsugid(); 348 if (p->p_tracep && suser(td)) { 349 struct vnode *vtmp; 350 351 if ((vtmp = p->p_tracep) != NULL) { 352 p->p_tracep = NULL; 353 p->p_traceflag = 0; 354 vrele(vtmp); 355 } 356 } 357 /* Close any file descriptors 0..2 that reference procfs */ 358 setugidsafety(p); 359 /* Make sure file descriptors 0..2 are in use. */ 360 error = fdcheckstd(p); 361 if (error != 0) 362 goto exec_fail_dealloc; 363 /* 364 * Set the new credentials. 365 */ 366 cratom(&p->p_ucred); 367 if (attr.va_mode & VSUID) 368 change_euid(attr.va_uid); 369 if (attr.va_mode & VSGID) 370 p->p_ucred->cr_gid = attr.va_gid; 371 372 /* 373 * Clear local varsym variables 374 */ 375 varsymset_clean(&p->p_varsymset); 376 } else { 377 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && 378 p->p_ucred->cr_gid == p->p_ucred->cr_rgid) 379 p->p_flag &= ~P_SUGID; 380 } 381 382 /* 383 * Implement correct POSIX saved-id behavior. 384 */ 385 if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || 386 p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { 387 cratom(&p->p_ucred); 388 p->p_ucred->cr_svuid = p->p_ucred->cr_uid; 389 p->p_ucred->cr_svgid = p->p_ucred->cr_gid; 390 } 391 392 /* 393 * Store the vp for use in procfs 394 */ 395 if (p->p_textvp) /* release old reference */ 396 vrele(p->p_textvp); 397 VREF(ndp->ni_vp); 398 p->p_textvp = ndp->ni_vp; 399 400 /* 401 * Notify others that we exec'd, and clear the P_INEXEC flag 402 * as we're now a bona fide freshly-execed process. 403 */ 404 KNOTE(&p->p_klist, NOTE_EXEC); 405 p->p_flag &= ~P_INEXEC; 406 407 /* 408 * If tracing the process, trap to debugger so breakpoints 409 * can be set before the program executes. 410 */ 411 STOPEVENT(p, S_EXEC, 0); 412 413 if (p->p_flag & P_TRACED) 414 psignal(p, SIGTRAP); 415 416 /* clear "fork but no exec" flag, as we _are_ execing */ 417 p->p_acflag &= ~AFORK; 418 419 /* Set values passed into the program in registers. */ 420 setregs(p, imgp->entry_addr, (u_long)(uintptr_t)stack_base, 421 imgp->ps_strings); 422 423 /* Free any previous argument cache */ 424 if (p->p_args && --p->p_args->ar_ref == 0) 425 FREE(p->p_args, M_PARGS); 426 p->p_args = NULL; 427 428 /* Cache arguments if they fit inside our allowance */ 429 i = imgp->args->begin_envv - imgp->args->begin_argv; 430 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 431 MALLOC(p->p_args, struct pargs *, sizeof(struct pargs) + i, 432 M_PARGS, M_WAITOK); 433 p->p_args->ar_ref = 1; 434 p->p_args->ar_length = i; 435 bcopy(imgp->args->begin_argv, p->p_args->ar_args, i); 436 } 437 438 exec_fail_dealloc: 439 440 /* 441 * free various allocated resources 442 */ 443 if (imgp->firstpage) 444 exec_unmap_first_page(imgp); 445 446 if (imgp->image_header != NULL) 447 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->image_header, 448 PAGE_SIZE); 449 450 if (imgp->vp) { 451 NDFREE(ndp, NDF_ONLY_PNBUF); 452 vrele(imgp->vp); 453 } 454 455 if (error == 0) 456 return (0); 457 458 exec_fail: 459 /* we're done here, clear P_INEXEC */ 460 p->p_flag &= ~P_INEXEC; 461 if (imgp->vmspace_destroyed) { 462 /* sorry, no more process anymore. exit gracefully */ 463 exit1(W_EXITCODE(0, SIGABRT)); 464 /* NOT REACHED */ 465 return(0); 466 } else { 467 return(error); 468 } 469 } 470 471 /* 472 * execve() system call. 473 */ 474 int 475 execve(struct execve_args *uap) 476 { 477 struct thread *td = curthread; 478 struct nameidata nd; 479 struct image_args args; 480 int error; 481 482 NDINIT(&nd, NAMEI_LOOKUP, CNP_LOCKLEAF | CNP_FOLLOW | CNP_SAVENAME, 483 UIO_USERSPACE, uap->fname, td); 484 485 error = exec_copyin_args(&args, uap->fname, PATH_USERSPACE, 486 uap->argv, uap->envv); 487 if (error == 0) 488 error = kern_execve(&nd, &args); 489 490 exec_free_args(&args); 491 492 /* 493 * The syscall result is returned in registers to the new program. 494 * Linux will register %edx as an atexit function and we must be 495 * sure to set it to 0. XXX 496 */ 497 if (error == 0) 498 uap->sysmsg_result64 = 0; 499 500 return (error); 501 } 502 503 int 504 exec_map_first_page(struct image_params *imgp) 505 { 506 int s, rv, i; 507 int initial_pagein; 508 vm_page_t ma[VM_INITIAL_PAGEIN]; 509 vm_object_t object; 510 511 512 if (imgp->firstpage) { 513 exec_unmap_first_page(imgp); 514 } 515 516 VOP_GETVOBJECT(imgp->vp, &object); 517 s = splvm(); 518 519 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 520 521 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 522 initial_pagein = VM_INITIAL_PAGEIN; 523 if (initial_pagein > object->size) 524 initial_pagein = object->size; 525 for (i = 1; i < initial_pagein; i++) { 526 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 527 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy) 528 break; 529 if (ma[i]->valid) 530 break; 531 vm_page_busy(ma[i]); 532 } else { 533 ma[i] = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 534 if (ma[i] == NULL) 535 break; 536 } 537 } 538 initial_pagein = i; 539 540 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 541 ma[0] = vm_page_lookup(object, 0); 542 543 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || (ma[0]->valid == 0)) { 544 if (ma[0]) { 545 vm_page_protect(ma[0], VM_PROT_NONE); 546 vm_page_free(ma[0]); 547 } 548 splx(s); 549 return EIO; 550 } 551 } 552 553 vm_page_wire(ma[0]); 554 vm_page_wakeup(ma[0]); 555 splx(s); 556 557 pmap_kenter((vm_offset_t) imgp->image_header, VM_PAGE_TO_PHYS(ma[0])); 558 imgp->firstpage = ma[0]; 559 560 return 0; 561 } 562 563 void 564 exec_unmap_first_page(imgp) 565 struct image_params *imgp; 566 { 567 if (imgp->firstpage) { 568 pmap_kremove((vm_offset_t) imgp->image_header); 569 vm_page_unwire(imgp->firstpage, 1); 570 imgp->firstpage = NULL; 571 } 572 } 573 574 /* 575 * Destroy old address space, and allocate a new stack 576 * The new stack is only SGROWSIZ large because it is grown 577 * automatically in trap.c. 578 */ 579 int 580 exec_new_vmspace(struct image_params *imgp, struct vmspace *vmcopy) 581 { 582 int error; 583 struct vmspace *vmspace = imgp->proc->p_vmspace; 584 vm_offset_t stack_addr = USRSTACK - maxssiz; 585 vm_map_t map; 586 587 imgp->vmspace_destroyed = 1; 588 589 /* 590 * Prevent a pending AIO from modifying the new address space. 591 */ 592 aio_proc_rundown(imgp->proc); 593 594 /* 595 * Blow away entire process VM, if address space not shared, 596 * otherwise, create a new VM space so that other threads are 597 * not disrupted. If we are execing a resident vmspace we 598 * create a duplicate of it and remap the stack. 599 */ 600 map = &vmspace->vm_map; 601 if (vmcopy) { 602 vmspace_exec(imgp->proc, vmcopy); 603 vmspace = imgp->proc->p_vmspace; 604 pmap_remove_pages(vmspace_pmap(vmspace), stack_addr, USRSTACK); 605 map = &vmspace->vm_map; 606 } else if (vmspace->vm_refcnt == 1) { 607 shmexit(vmspace); 608 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); 609 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); 610 } else { 611 vmspace_exec(imgp->proc, NULL); 612 vmspace = imgp->proc->p_vmspace; 613 map = &vmspace->vm_map; 614 } 615 616 /* Allocate a new stack */ 617 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 618 VM_PROT_ALL, VM_PROT_ALL, 0); 619 if (error) 620 return (error); 621 622 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 623 * VM_STACK case, but they are still used to monitor the size of the 624 * process stack so we can check the stack rlimit. 625 */ 626 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 627 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 628 629 return(0); 630 } 631 632 /* 633 * Copy out argument and environment strings from the old process 634 * address space into the temporary string buffer. 635 */ 636 int 637 exec_copyin_args(struct image_args *args, char *fname, 638 enum exec_path_segflg segflg, char **argv, char **envv) 639 { 640 char *argp, *envp; 641 int error = 0; 642 size_t length; 643 644 bzero(args, sizeof(*args)); 645 args->buf = (char *) kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 646 if (args->buf == NULL) 647 return (ENOMEM); 648 args->begin_argv = args->buf; 649 args->endp = args->begin_argv; 650 args->space = ARG_MAX; 651 652 args->fname = args->buf + ARG_MAX; 653 654 /* 655 * Copy the file name. 656 */ 657 if (segflg == PATH_SYSSPACE) { 658 error = copystr(fname, args->fname, PATH_MAX, &length); 659 } else if (segflg == PATH_USERSPACE) { 660 error = copyinstr(fname, args->fname, PATH_MAX, &length); 661 } 662 663 /* 664 * extract argument strings 665 */ 666 667 if (argv && error == 0) { 668 /* 669 * The argv0 argument for execv() is allowed to be NULL, 670 * in which case we use our filename as argv[0]. 671 * This guarantees that 672 * the interpreter knows what file to open in the case 673 * that we exec an interpreted file. 674 */ 675 argp = (caddr_t) (intptr_t) fuword(argv); 676 if (argp == NULL) { 677 length = strlen(args->fname) + 1; 678 KKASSERT(length <= args->space); 679 bcopy(args->fname, args->endp, length); 680 args->space -= length; 681 args->endp += length; 682 args->argc++; 683 argv++; 684 } 685 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 686 if (argp == (caddr_t) -1) { 687 error = EFAULT; 688 goto cleanup; 689 } 690 error = copyinstr(argp, args->endp, 691 args->space, &length); 692 if (error == ENAMETOOLONG) 693 error = E2BIG; 694 if (error) 695 goto cleanup; 696 args->space -= length; 697 args->endp += length; 698 args->argc++; 699 } 700 } 701 702 args->begin_envv = args->endp; 703 704 /* 705 * extract environment strings 706 */ 707 if (envv && error == 0) { 708 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 709 if (envp == (caddr_t) -1) { 710 error = EFAULT; 711 goto cleanup; 712 } 713 error = copyinstr(envp, args->endp, args->space, 714 &length); 715 if (error == ENAMETOOLONG) 716 error = E2BIG; 717 if (error) 718 goto cleanup; 719 args->space -= length; 720 args->endp += length; 721 args->envc++; 722 } 723 } 724 725 cleanup: 726 return (error); 727 } 728 729 void 730 exec_free_args(struct image_args *args) 731 { 732 if (args->buf) { 733 kmem_free_wakeup(exec_map, 734 (vm_offset_t)args->buf, PATH_MAX + ARG_MAX); 735 args->buf = NULL; 736 } 737 } 738 739 /* 740 * Copy strings out to the new process address space, constructing 741 * new arg and env vector tables. Return a pointer to the base 742 * so that it can be used as the initial stack pointer. 743 */ 744 register_t * 745 exec_copyout_strings(struct image_params *imgp) 746 { 747 int argc, envc; 748 char **vectp; 749 char *stringp, *destp; 750 register_t *stack_base; 751 struct ps_strings *arginfo; 752 int szsigcode; 753 754 /* 755 * Calculate string base and vector table pointers. 756 * Also deal with signal trampoline code for this exec type. 757 */ 758 arginfo = (struct ps_strings *)PS_STRINGS; 759 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 760 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 761 roundup((ARG_MAX - imgp->args->space), sizeof(char *)); 762 763 /* 764 * install sigcode 765 */ 766 if (szsigcode) 767 copyout(imgp->proc->p_sysent->sv_sigcode, 768 ((caddr_t)arginfo - szsigcode), szsigcode); 769 770 /* 771 * If we have a valid auxargs ptr, prepare some room 772 * on the stack. 773 * 774 * The '+ 2' is for the null pointers at the end of each of the 775 * arg and env vector sets, and 'AT_COUNT*2' is room for the 776 * ELF Auxargs data. 777 */ 778 if (imgp->auxargs) { 779 vectp = (char **)(destp - (imgp->args->argc + 780 imgp->args->envc + 2 + AT_COUNT * 2) * sizeof(char*)); 781 } else { 782 vectp = (char **)(destp - (imgp->args->argc + 783 imgp->args->envc + 2) * sizeof(char*)); 784 } 785 786 /* 787 * NOTE: don't bother aligning the stack here for GCC 2.x, it will 788 * be done in crt1.o. Note that GCC 3.x aligns the stack in main. 789 */ 790 791 /* 792 * vectp also becomes our initial stack base 793 */ 794 stack_base = (register_t *)vectp; 795 796 stringp = imgp->args->begin_argv; 797 argc = imgp->args->argc; 798 envc = imgp->args->envc; 799 800 /* 801 * Copy out strings - arguments and environment. 802 */ 803 copyout(stringp, destp, ARG_MAX - imgp->args->space); 804 805 /* 806 * Fill in "ps_strings" struct for ps, w, etc. 807 */ 808 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 809 suword(&arginfo->ps_nargvstr, argc); 810 811 /* 812 * Fill in argument portion of vector table. 813 */ 814 for (; argc > 0; --argc) { 815 suword(vectp++, (long)(intptr_t)destp); 816 while (*stringp++ != 0) 817 destp++; 818 destp++; 819 } 820 821 /* a null vector table pointer separates the argp's from the envp's */ 822 suword(vectp++, 0); 823 824 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 825 suword(&arginfo->ps_nenvstr, envc); 826 827 /* 828 * Fill in environment portion of vector table. 829 */ 830 for (; envc > 0; --envc) { 831 suword(vectp++, (long)(intptr_t)destp); 832 while (*stringp++ != 0) 833 destp++; 834 destp++; 835 } 836 837 /* end of vector table is a null pointer */ 838 suword(vectp, 0); 839 840 return (stack_base); 841 } 842 843 /* 844 * Check permissions of file to execute. 845 * Return 0 for success or error code on failure. 846 */ 847 int 848 exec_check_permissions(imgp) 849 struct image_params *imgp; 850 { 851 struct proc *p = imgp->proc; 852 struct vnode *vp = imgp->vp; 853 struct vattr *attr = imgp->attr; 854 struct thread *td = p->p_thread; 855 int error; 856 857 /* Get file attributes */ 858 error = VOP_GETATTR(vp, attr, td); 859 if (error) 860 return (error); 861 862 /* 863 * 1) Check if file execution is disabled for the filesystem that this 864 * file resides on. 865 * 2) Insure that at least one execute bit is on - otherwise root 866 * will always succeed, and we don't want to happen unless the 867 * file really is executable. 868 * 3) Insure that the file is a regular file. 869 */ 870 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 871 ((attr->va_mode & 0111) == 0) || 872 (attr->va_type != VREG)) { 873 return (EACCES); 874 } 875 876 /* 877 * Zero length files can't be exec'd 878 */ 879 if (attr->va_size == 0) 880 return (ENOEXEC); 881 882 /* 883 * Check for execute permission to file based on current credentials. 884 */ 885 error = VOP_ACCESS(vp, VEXEC, p->p_ucred, td); 886 if (error) 887 return (error); 888 889 /* 890 * Check number of open-for-writes on the file and deny execution 891 * if there are any. 892 */ 893 if (vp->v_writecount) 894 return (ETXTBSY); 895 896 /* 897 * Call filesystem specific open routine (which does nothing in the 898 * general case). 899 */ 900 error = VOP_OPEN(vp, FREAD, p->p_ucred, td); 901 if (error) 902 return (error); 903 904 return (0); 905 } 906 907 /* 908 * Exec handler registration 909 */ 910 int 911 exec_register(execsw_arg) 912 const struct execsw *execsw_arg; 913 { 914 const struct execsw **es, **xs, **newexecsw; 915 int count = 2; /* New slot and trailing NULL */ 916 917 if (execsw) 918 for (es = execsw; *es; es++) 919 count++; 920 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 921 if (newexecsw == NULL) 922 return ENOMEM; 923 xs = newexecsw; 924 if (execsw) 925 for (es = execsw; *es; es++) 926 *xs++ = *es; 927 *xs++ = execsw_arg; 928 *xs = NULL; 929 if (execsw) 930 free(execsw, M_TEMP); 931 execsw = newexecsw; 932 return 0; 933 } 934 935 int 936 exec_unregister(execsw_arg) 937 const struct execsw *execsw_arg; 938 { 939 const struct execsw **es, **xs, **newexecsw; 940 int count = 1; 941 942 if (execsw == NULL) 943 panic("unregister with no handlers left?\n"); 944 945 for (es = execsw; *es; es++) { 946 if (*es == execsw_arg) 947 break; 948 } 949 if (*es == NULL) 950 return ENOENT; 951 for (es = execsw; *es; es++) 952 if (*es != execsw_arg) 953 count++; 954 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 955 if (newexecsw == NULL) 956 return ENOMEM; 957 xs = newexecsw; 958 for (es = execsw; *es; es++) 959 if (*es != execsw_arg) 960 *xs++ = *es; 961 *xs = NULL; 962 if (execsw) 963 free(execsw, M_TEMP); 964 execsw = newexecsw; 965 return 0; 966 } 967