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 1.22 2004/04/11 00:10:30 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/sfbuf.h> 49 #include <sys/sysent.h> 50 #include <sys/shm.h> 51 #include <sys/sysctl.h> 52 #include <sys/vnode.h> 53 #include <sys/aio.h> 54 55 #include <vm/vm.h> 56 #include <vm/vm_param.h> 57 #include <sys/lock.h> 58 #include <vm/pmap.h> 59 #include <vm/vm_page.h> 60 #include <vm/vm_map.h> 61 #include <vm/vm_kern.h> 62 #include <vm/vm_extern.h> 63 #include <vm/vm_object.h> 64 #include <vm/vm_pager.h> 65 66 #include <sys/user.h> 67 #include <machine/reg.h> 68 69 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 70 71 static register_t *exec_copyout_strings (struct image_params *); 72 73 /* XXX This should be vm_size_t. */ 74 static u_long ps_strings = PS_STRINGS; 75 SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, ""); 76 77 /* XXX This should be vm_size_t. */ 78 static u_long usrstack = USRSTACK; 79 SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, ""); 80 81 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 82 SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 83 &ps_arg_cache_limit, 0, ""); 84 85 int ps_argsopen = 1; 86 SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, ""); 87 88 void print_execve_args(struct image_args *args); 89 int debug_execve_args = 0; 90 SYSCTL_INT(_kern, OID_AUTO, debug_execve_args, CTLFLAG_RW, &debug_execve_args, 91 0, ""); 92 93 void 94 print_execve_args(struct image_args *args) 95 { 96 char *cp; 97 int ndx; 98 99 cp = args->begin_argv; 100 for (ndx = 0; ndx < args->argc; ndx++) { 101 printf("\targv[%d]: %s\n", ndx, cp); 102 while (*cp++ != '\0'); 103 } 104 for (ndx = 0; ndx < args->envc; ndx++) { 105 printf("\tenvv[%d]: %s\n", ndx, cp); 106 while (*cp++ != '\0'); 107 } 108 } 109 110 /* 111 * Each of the items is a pointer to a `const struct execsw', hence the 112 * double pointer here. 113 */ 114 static const struct execsw **execsw; 115 116 int 117 kern_execve(struct nameidata *ndp, struct image_args *args) 118 { 119 struct thread *td = curthread; 120 struct proc *p = td->td_proc; 121 register_t *stack_base; 122 int error, len, i; 123 struct image_params image_params, *imgp; 124 struct vattr attr; 125 int (*img_first) (struct image_params *); 126 127 if (debug_execve_args) { 128 printf("%s()\n", __func__); 129 print_execve_args(args); 130 } 131 132 KKASSERT(p); 133 imgp = &image_params; 134 135 /* 136 * Lock the process and set the P_INEXEC flag to indicate that 137 * it should be left alone until we're done here. This is 138 * necessary to avoid race conditions - e.g. in ptrace() - 139 * that might allow a local user to illicitly obtain elevated 140 * privileges. 141 */ 142 p->p_flag |= P_INEXEC; 143 144 /* 145 * Initialize part of the common data 146 */ 147 imgp->proc = p; 148 imgp->args = args; 149 imgp->attr = &attr; 150 imgp->entry_addr = 0; 151 imgp->resident = 0; 152 imgp->vmspace_destroyed = 0; 153 imgp->interpreted = 0; 154 imgp->interpreter_name[0] = 0; 155 imgp->auxargs = NULL; 156 imgp->vp = NULL; 157 imgp->firstpage = NULL; 158 imgp->ps_strings = 0; 159 imgp->image_header = NULL; 160 161 interpret: 162 163 /* 164 * Translate the file name. namei() returns a vnode pointer 165 * in ni_vp amoung other things. 166 */ 167 if ((error = namei(ndp)) != 0) 168 goto exec_fail; 169 170 imgp->vp = ndp->ni_vp; 171 172 /* 173 * Check file permissions (also 'opens' file) 174 */ 175 error = exec_check_permissions(imgp); 176 if (error) { 177 VOP_UNLOCK(imgp->vp, NULL, 0, td); 178 goto exec_fail_dealloc; 179 } 180 181 error = exec_map_first_page(imgp); 182 VOP_UNLOCK(imgp->vp, NULL, 0, td); 183 if (error) 184 goto exec_fail_dealloc; 185 186 if (debug_execve_args && imgp->interpreted) { 187 printf(" target is interpreted -- recursive pass\n"); 188 printf(" interpreter: %s\n", imgp->interpreter_name); 189 print_execve_args(args); 190 } 191 192 /* 193 * If the current process has a special image activator it 194 * wants to try first, call it. For example, emulating shell 195 * scripts differently. 196 */ 197 error = -1; 198 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 199 error = img_first(imgp); 200 201 /* 202 * If the vnode has a registered vmspace, exec the vmspace 203 */ 204 if (error == -1 && imgp->vp->v_resident) { 205 error = exec_resident_imgact(imgp); 206 } 207 208 /* 209 * Loop through the list of image activators, calling each one. 210 * An activator returns -1 if there is no match, 0 on success, 211 * and an error otherwise. 212 */ 213 for (i = 0; error == -1 && execsw[i]; ++i) { 214 if (execsw[i]->ex_imgact == NULL || 215 execsw[i]->ex_imgact == img_first) { 216 continue; 217 } 218 error = (*execsw[i]->ex_imgact)(imgp); 219 } 220 221 if (error) { 222 if (error == -1) 223 error = ENOEXEC; 224 goto exec_fail_dealloc; 225 } 226 227 /* 228 * Special interpreter operation, cleanup and loop up to try to 229 * activate the interpreter. 230 */ 231 if (imgp->interpreted) { 232 exec_unmap_first_page(imgp); 233 /* free name buffer and old vnode */ 234 NDFREE(ndp, NDF_ONLY_PNBUF); 235 vrele(ndp->ni_vp); 236 /* set new name to that of the interpreter */ 237 NDINIT(ndp, NAMEI_LOOKUP, 238 CNP_LOCKLEAF | CNP_FOLLOW | CNP_SAVENAME, 239 UIO_SYSSPACE, imgp->interpreter_name, td); 240 goto interpret; 241 } 242 243 /* 244 * Copy out strings (args and env) and initialize stack base 245 */ 246 stack_base = exec_copyout_strings(imgp); 247 p->p_vmspace->vm_minsaddr = (char *)stack_base; 248 249 /* 250 * If custom stack fixup routine present for this process 251 * let it do the stack setup. If we are running a resident 252 * image there is no auxinfo or other image activator context 253 * so don't try to add fixups to the stack. 254 * 255 * Else stuff argument count as first item on stack 256 */ 257 if (p->p_sysent->sv_fixup && imgp->resident == 0) 258 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 259 else 260 suword(--stack_base, imgp->args->argc); 261 262 /* 263 * For security and other reasons, the file descriptor table cannot 264 * be shared after an exec. 265 */ 266 if (p->p_fd->fd_refcnt > 1) { 267 struct filedesc *tmp; 268 269 tmp = fdcopy(p); 270 fdfree(p); 271 p->p_fd = tmp; 272 } 273 274 /* 275 * For security and other reasons, signal handlers cannot 276 * be shared after an exec. The new proces gets a copy of the old 277 * handlers. In execsigs(), the new process will have its signals 278 * reset. 279 */ 280 if (p->p_procsig->ps_refcnt > 1) { 281 struct procsig *newprocsig; 282 283 MALLOC(newprocsig, struct procsig *, sizeof(struct procsig), 284 M_SUBPROC, M_WAITOK); 285 bcopy(p->p_procsig, newprocsig, sizeof(*newprocsig)); 286 p->p_procsig->ps_refcnt--; 287 p->p_procsig = newprocsig; 288 p->p_procsig->ps_refcnt = 1; 289 if (p->p_sigacts == &p->p_addr->u_sigacts) 290 panic("shared procsig but private sigacts?"); 291 292 p->p_addr->u_sigacts = *p->p_sigacts; 293 p->p_sigacts = &p->p_addr->u_sigacts; 294 } 295 296 /* Stop profiling */ 297 stopprofclock(p); 298 299 /* close files on exec */ 300 fdcloseexec(p); 301 302 /* reset caught signals */ 303 execsigs(p); 304 305 /* name this process - nameiexec(p, ndp) */ 306 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 307 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 308 p->p_comm[len] = 0; 309 310 /* 311 * mark as execed, wakeup the process that vforked (if any) and tell 312 * it that it now has its own resources back 313 */ 314 p->p_flag |= P_EXEC; 315 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 316 p->p_flag &= ~P_PPWAIT; 317 wakeup((caddr_t)p->p_pptr); 318 } 319 320 /* 321 * Implement image setuid/setgid. 322 * 323 * Don't honor setuid/setgid if the filesystem prohibits it or if 324 * the process is being traced. 325 */ 326 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 327 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 328 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 329 (p->p_flag & P_TRACED) == 0) { 330 /* 331 * Turn off syscall tracing for set-id programs, except for 332 * root. Record any set-id flags first to make sure that 333 * we do not regain any tracing during a possible block. 334 */ 335 setsugid(); 336 if (p->p_tracep && suser(td)) { 337 struct vnode *vtmp; 338 339 if ((vtmp = p->p_tracep) != NULL) { 340 p->p_tracep = NULL; 341 p->p_traceflag = 0; 342 vrele(vtmp); 343 } 344 } 345 /* Close any file descriptors 0..2 that reference procfs */ 346 setugidsafety(p); 347 /* Make sure file descriptors 0..2 are in use. */ 348 error = fdcheckstd(p); 349 if (error != 0) 350 goto exec_fail_dealloc; 351 /* 352 * Set the new credentials. 353 */ 354 cratom(&p->p_ucred); 355 if (attr.va_mode & VSUID) 356 change_euid(attr.va_uid); 357 if (attr.va_mode & VSGID) 358 p->p_ucred->cr_gid = attr.va_gid; 359 360 /* 361 * Clear local varsym variables 362 */ 363 varsymset_clean(&p->p_varsymset); 364 } else { 365 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && 366 p->p_ucred->cr_gid == p->p_ucred->cr_rgid) 367 p->p_flag &= ~P_SUGID; 368 } 369 370 /* 371 * Implement correct POSIX saved-id behavior. 372 */ 373 if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || 374 p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { 375 cratom(&p->p_ucred); 376 p->p_ucred->cr_svuid = p->p_ucred->cr_uid; 377 p->p_ucred->cr_svgid = p->p_ucred->cr_gid; 378 } 379 380 /* 381 * Store the vp for use in procfs 382 */ 383 if (p->p_textvp) /* release old reference */ 384 vrele(p->p_textvp); 385 VREF(ndp->ni_vp); 386 p->p_textvp = ndp->ni_vp; 387 388 /* 389 * Notify others that we exec'd, and clear the P_INEXEC flag 390 * as we're now a bona fide freshly-execed process. 391 */ 392 KNOTE(&p->p_klist, NOTE_EXEC); 393 p->p_flag &= ~P_INEXEC; 394 395 /* 396 * If tracing the process, trap to debugger so breakpoints 397 * can be set before the program executes. 398 */ 399 STOPEVENT(p, S_EXEC, 0); 400 401 if (p->p_flag & P_TRACED) 402 psignal(p, SIGTRAP); 403 404 /* clear "fork but no exec" flag, as we _are_ execing */ 405 p->p_acflag &= ~AFORK; 406 407 /* Set values passed into the program in registers. */ 408 setregs(p, imgp->entry_addr, (u_long)(uintptr_t)stack_base, 409 imgp->ps_strings); 410 411 /* Free any previous argument cache */ 412 if (p->p_args && --p->p_args->ar_ref == 0) 413 FREE(p->p_args, M_PARGS); 414 p->p_args = NULL; 415 416 /* Cache arguments if they fit inside our allowance */ 417 i = imgp->args->begin_envv - imgp->args->begin_argv; 418 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 419 MALLOC(p->p_args, struct pargs *, sizeof(struct pargs) + i, 420 M_PARGS, M_WAITOK); 421 p->p_args->ar_ref = 1; 422 p->p_args->ar_length = i; 423 bcopy(imgp->args->begin_argv, p->p_args->ar_args, i); 424 } 425 426 exec_fail_dealloc: 427 428 /* 429 * free various allocated resources 430 */ 431 if (imgp->firstpage) 432 exec_unmap_first_page(imgp); 433 434 if (imgp->vp) { 435 NDFREE(ndp, NDF_ONLY_PNBUF); 436 vrele(imgp->vp); 437 } 438 439 if (error == 0) 440 return (0); 441 442 exec_fail: 443 /* we're done here, clear P_INEXEC */ 444 p->p_flag &= ~P_INEXEC; 445 if (imgp->vmspace_destroyed) { 446 /* sorry, no more process anymore. exit gracefully */ 447 exit1(W_EXITCODE(0, SIGABRT)); 448 /* NOT REACHED */ 449 return(0); 450 } else { 451 return(error); 452 } 453 } 454 455 /* 456 * execve() system call. 457 */ 458 int 459 execve(struct execve_args *uap) 460 { 461 struct thread *td = curthread; 462 struct nameidata nd; 463 struct image_args args; 464 int error; 465 466 NDINIT(&nd, NAMEI_LOOKUP, CNP_LOCKLEAF | CNP_FOLLOW | CNP_SAVENAME, 467 UIO_USERSPACE, uap->fname, td); 468 469 error = exec_copyin_args(&args, uap->fname, PATH_USERSPACE, 470 uap->argv, uap->envv); 471 if (error == 0) 472 error = kern_execve(&nd, &args); 473 474 exec_free_args(&args); 475 476 /* 477 * The syscall result is returned in registers to the new program. 478 * Linux will register %edx as an atexit function and we must be 479 * sure to set it to 0. XXX 480 */ 481 if (error == 0) 482 uap->sysmsg_result64 = 0; 483 484 return (error); 485 } 486 487 int 488 exec_map_first_page(struct image_params *imgp) 489 { 490 int s, rv, i; 491 int initial_pagein; 492 vm_page_t ma[VM_INITIAL_PAGEIN]; 493 vm_object_t object; 494 495 if (imgp->firstpage) 496 exec_unmap_first_page(imgp); 497 498 VOP_GETVOBJECT(imgp->vp, &object); 499 s = splvm(); 500 501 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 502 503 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 504 initial_pagein = VM_INITIAL_PAGEIN; 505 if (initial_pagein > object->size) 506 initial_pagein = object->size; 507 for (i = 1; i < initial_pagein; i++) { 508 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 509 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy) 510 break; 511 if (ma[i]->valid) 512 break; 513 vm_page_busy(ma[i]); 514 } else { 515 ma[i] = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 516 if (ma[i] == NULL) 517 break; 518 } 519 } 520 initial_pagein = i; 521 522 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 523 ma[0] = vm_page_lookup(object, 0); 524 525 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || (ma[0]->valid == 0)) { 526 if (ma[0]) { 527 vm_page_protect(ma[0], VM_PROT_NONE); 528 vm_page_free(ma[0]); 529 } 530 splx(s); 531 return EIO; 532 } 533 } 534 535 vm_page_wire(ma[0]); 536 vm_page_wakeup(ma[0]); 537 splx(s); 538 539 imgp->firstpage = sf_buf_alloc(ma[0], SFBA_QUICK); 540 imgp->image_header = (void *)sf_buf_kva(imgp->firstpage); 541 542 return 0; 543 } 544 545 void 546 exec_unmap_first_page(imgp) 547 struct image_params *imgp; 548 { 549 vm_page_t m; 550 551 if (imgp->firstpage != NULL) { 552 m = sf_buf_page(imgp->firstpage); 553 sf_buf_free(imgp->firstpage); 554 imgp->firstpage = NULL; 555 imgp->image_header = NULL; 556 vm_page_unwire(m, 1); 557 } 558 } 559 560 /* 561 * Destroy old address space, and allocate a new stack 562 * The new stack is only SGROWSIZ large because it is grown 563 * automatically in trap.c. 564 */ 565 int 566 exec_new_vmspace(struct image_params *imgp, struct vmspace *vmcopy) 567 { 568 int error; 569 struct vmspace *vmspace = imgp->proc->p_vmspace; 570 vm_offset_t stack_addr = USRSTACK - maxssiz; 571 vm_map_t map; 572 573 imgp->vmspace_destroyed = 1; 574 575 /* 576 * Prevent a pending AIO from modifying the new address space. 577 */ 578 aio_proc_rundown(imgp->proc); 579 580 /* 581 * Blow away entire process VM, if address space not shared, 582 * otherwise, create a new VM space so that other threads are 583 * not disrupted. If we are execing a resident vmspace we 584 * create a duplicate of it and remap the stack. 585 * 586 * The exitingcnt test is not strictly necessary but has been 587 * included for code sanity (to make the code more deterministic). 588 */ 589 map = &vmspace->vm_map; 590 if (vmcopy) { 591 vmspace_exec(imgp->proc, vmcopy); 592 vmspace = imgp->proc->p_vmspace; 593 pmap_remove_pages(vmspace_pmap(vmspace), stack_addr, USRSTACK); 594 map = &vmspace->vm_map; 595 } else if (vmspace->vm_refcnt == 1 && vmspace->vm_exitingcnt == 0) { 596 shmexit(vmspace); 597 if (vmspace->vm_upcalls) 598 upc_release(vmspace, imgp->proc); 599 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); 600 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); 601 } else { 602 vmspace_exec(imgp->proc, NULL); 603 vmspace = imgp->proc->p_vmspace; 604 map = &vmspace->vm_map; 605 } 606 607 /* Allocate a new stack */ 608 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 609 VM_PROT_ALL, VM_PROT_ALL, 0); 610 if (error) 611 return (error); 612 613 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 614 * VM_STACK case, but they are still used to monitor the size of the 615 * process stack so we can check the stack rlimit. 616 */ 617 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 618 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 619 620 return(0); 621 } 622 623 /* 624 * Copy out argument and environment strings from the old process 625 * address space into the temporary string buffer. 626 */ 627 int 628 exec_copyin_args(struct image_args *args, char *fname, 629 enum exec_path_segflg segflg, char **argv, char **envv) 630 { 631 char *argp, *envp; 632 int error = 0; 633 size_t length; 634 635 bzero(args, sizeof(*args)); 636 args->buf = (char *) kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 637 if (args->buf == NULL) 638 return (ENOMEM); 639 args->begin_argv = args->buf; 640 args->endp = args->begin_argv; 641 args->space = ARG_MAX; 642 643 args->fname = args->buf + ARG_MAX; 644 645 /* 646 * Copy the file name. 647 */ 648 if (segflg == PATH_SYSSPACE) { 649 error = copystr(fname, args->fname, PATH_MAX, &length); 650 } else if (segflg == PATH_USERSPACE) { 651 error = copyinstr(fname, args->fname, PATH_MAX, &length); 652 } 653 654 /* 655 * extract argument strings 656 */ 657 658 if (argv && error == 0) { 659 /* 660 * The argv0 argument for execv() is allowed to be NULL, 661 * in which case we use our filename as argv[0]. 662 * This guarantees that 663 * the interpreter knows what file to open in the case 664 * that we exec an interpreted file. 665 */ 666 argp = (caddr_t) (intptr_t) fuword(argv); 667 if (argp == NULL) { 668 length = strlen(args->fname) + 1; 669 KKASSERT(length <= args->space); 670 bcopy(args->fname, args->endp, length); 671 args->space -= length; 672 args->endp += length; 673 args->argc++; 674 argv++; 675 } 676 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 677 if (argp == (caddr_t) -1) { 678 error = EFAULT; 679 goto cleanup; 680 } 681 error = copyinstr(argp, args->endp, 682 args->space, &length); 683 if (error == ENAMETOOLONG) 684 error = E2BIG; 685 if (error) 686 goto cleanup; 687 args->space -= length; 688 args->endp += length; 689 args->argc++; 690 } 691 } 692 693 args->begin_envv = args->endp; 694 695 /* 696 * extract environment strings 697 */ 698 if (envv && error == 0) { 699 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 700 if (envp == (caddr_t) -1) { 701 error = EFAULT; 702 goto cleanup; 703 } 704 error = copyinstr(envp, args->endp, args->space, 705 &length); 706 if (error == ENAMETOOLONG) 707 error = E2BIG; 708 if (error) 709 goto cleanup; 710 args->space -= length; 711 args->endp += length; 712 args->envc++; 713 } 714 } 715 716 cleanup: 717 return (error); 718 } 719 720 void 721 exec_free_args(struct image_args *args) 722 { 723 if (args->buf) { 724 kmem_free_wakeup(exec_map, 725 (vm_offset_t)args->buf, PATH_MAX + ARG_MAX); 726 args->buf = NULL; 727 } 728 } 729 730 /* 731 * Copy strings out to the new process address space, constructing 732 * new arg and env vector tables. Return a pointer to the base 733 * so that it can be used as the initial stack pointer. 734 */ 735 register_t * 736 exec_copyout_strings(struct image_params *imgp) 737 { 738 int argc, envc; 739 char **vectp; 740 char *stringp, *destp; 741 register_t *stack_base; 742 struct ps_strings *arginfo; 743 int szsigcode; 744 745 /* 746 * Calculate string base and vector table pointers. 747 * Also deal with signal trampoline code for this exec type. 748 */ 749 arginfo = (struct ps_strings *)PS_STRINGS; 750 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 751 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 752 roundup((ARG_MAX - imgp->args->space), sizeof(char *)); 753 754 /* 755 * install sigcode 756 */ 757 if (szsigcode) 758 copyout(imgp->proc->p_sysent->sv_sigcode, 759 ((caddr_t)arginfo - szsigcode), szsigcode); 760 761 /* 762 * If we have a valid auxargs ptr, prepare some room 763 * on the stack. 764 * 765 * The '+ 2' is for the null pointers at the end of each of the 766 * arg and env vector sets, and 'AT_COUNT*2' is room for the 767 * ELF Auxargs data. 768 */ 769 if (imgp->auxargs) { 770 vectp = (char **)(destp - (imgp->args->argc + 771 imgp->args->envc + 2 + AT_COUNT * 2) * sizeof(char*)); 772 } else { 773 vectp = (char **)(destp - (imgp->args->argc + 774 imgp->args->envc + 2) * sizeof(char*)); 775 } 776 777 /* 778 * NOTE: don't bother aligning the stack here for GCC 2.x, it will 779 * be done in crt1.o. Note that GCC 3.x aligns the stack in main. 780 */ 781 782 /* 783 * vectp also becomes our initial stack base 784 */ 785 stack_base = (register_t *)vectp; 786 787 stringp = imgp->args->begin_argv; 788 argc = imgp->args->argc; 789 envc = imgp->args->envc; 790 791 /* 792 * Copy out strings - arguments and environment. 793 */ 794 copyout(stringp, destp, ARG_MAX - imgp->args->space); 795 796 /* 797 * Fill in "ps_strings" struct for ps, w, etc. 798 */ 799 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 800 suword(&arginfo->ps_nargvstr, argc); 801 802 /* 803 * Fill in argument portion of vector table. 804 */ 805 for (; argc > 0; --argc) { 806 suword(vectp++, (long)(intptr_t)destp); 807 while (*stringp++ != 0) 808 destp++; 809 destp++; 810 } 811 812 /* a null vector table pointer separates the argp's from the envp's */ 813 suword(vectp++, 0); 814 815 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 816 suword(&arginfo->ps_nenvstr, envc); 817 818 /* 819 * Fill in environment portion of vector table. 820 */ 821 for (; envc > 0; --envc) { 822 suword(vectp++, (long)(intptr_t)destp); 823 while (*stringp++ != 0) 824 destp++; 825 destp++; 826 } 827 828 /* end of vector table is a null pointer */ 829 suword(vectp, 0); 830 831 return (stack_base); 832 } 833 834 /* 835 * Check permissions of file to execute. 836 * Return 0 for success or error code on failure. 837 */ 838 int 839 exec_check_permissions(imgp) 840 struct image_params *imgp; 841 { 842 struct proc *p = imgp->proc; 843 struct vnode *vp = imgp->vp; 844 struct vattr *attr = imgp->attr; 845 struct thread *td = p->p_thread; 846 int error; 847 848 /* Get file attributes */ 849 error = VOP_GETATTR(vp, attr, td); 850 if (error) 851 return (error); 852 853 /* 854 * 1) Check if file execution is disabled for the filesystem that this 855 * file resides on. 856 * 2) Insure that at least one execute bit is on - otherwise root 857 * will always succeed, and we don't want to happen unless the 858 * file really is executable. 859 * 3) Insure that the file is a regular file. 860 */ 861 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 862 ((attr->va_mode & 0111) == 0) || 863 (attr->va_type != VREG)) { 864 return (EACCES); 865 } 866 867 /* 868 * Zero length files can't be exec'd 869 */ 870 if (attr->va_size == 0) 871 return (ENOEXEC); 872 873 /* 874 * Check for execute permission to file based on current credentials. 875 */ 876 error = VOP_ACCESS(vp, VEXEC, p->p_ucred, td); 877 if (error) 878 return (error); 879 880 /* 881 * Check number of open-for-writes on the file and deny execution 882 * if there are any. 883 */ 884 if (vp->v_writecount) 885 return (ETXTBSY); 886 887 /* 888 * Call filesystem specific open routine (which does nothing in the 889 * general case). 890 */ 891 error = VOP_OPEN(vp, FREAD, p->p_ucred, td); 892 if (error) 893 return (error); 894 895 return (0); 896 } 897 898 /* 899 * Exec handler registration 900 */ 901 int 902 exec_register(execsw_arg) 903 const struct execsw *execsw_arg; 904 { 905 const struct execsw **es, **xs, **newexecsw; 906 int count = 2; /* New slot and trailing NULL */ 907 908 if (execsw) 909 for (es = execsw; *es; es++) 910 count++; 911 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 912 if (newexecsw == NULL) 913 return ENOMEM; 914 xs = newexecsw; 915 if (execsw) 916 for (es = execsw; *es; es++) 917 *xs++ = *es; 918 *xs++ = execsw_arg; 919 *xs = NULL; 920 if (execsw) 921 free(execsw, M_TEMP); 922 execsw = newexecsw; 923 return 0; 924 } 925 926 int 927 exec_unregister(execsw_arg) 928 const struct execsw *execsw_arg; 929 { 930 const struct execsw **es, **xs, **newexecsw; 931 int count = 1; 932 933 if (execsw == NULL) 934 panic("unregister with no handlers left?\n"); 935 936 for (es = execsw; *es; es++) { 937 if (*es == execsw_arg) 938 break; 939 } 940 if (*es == NULL) 941 return ENOENT; 942 for (es = execsw; *es; es++) 943 if (*es != execsw_arg) 944 count++; 945 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 946 if (newexecsw == NULL) 947 return ENOMEM; 948 xs = newexecsw; 949 for (es = execsw; *es; es++) 950 if (*es != execsw_arg) 951 *xs++ = *es; 952 *xs = NULL; 953 if (execsw) 954 free(execsw, M_TEMP); 955 execsw = newexecsw; 956 return 0; 957 } 958