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 1.29 2004/11/12 00:09:23 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/nlookup.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/vmmeter.h> 54 #include <sys/aio.h> 55 56 #include <vm/vm.h> 57 #include <vm/vm_param.h> 58 #include <sys/lock.h> 59 #include <vm/pmap.h> 60 #include <vm/vm_page.h> 61 #include <vm/vm_map.h> 62 #include <vm/vm_kern.h> 63 #include <vm/vm_extern.h> 64 #include <vm/vm_object.h> 65 #include <vm/vm_pager.h> 66 67 #include <sys/user.h> 68 #include <machine/reg.h> 69 70 #include <sys/thread2.h> 71 72 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 73 74 static register_t *exec_copyout_strings (struct image_params *); 75 76 /* XXX This should be vm_size_t. */ 77 static u_long ps_strings = PS_STRINGS; 78 SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, ""); 79 80 /* XXX This should be vm_size_t. */ 81 static u_long usrstack = USRSTACK; 82 SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, ""); 83 84 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 85 SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 86 &ps_arg_cache_limit, 0, ""); 87 88 int ps_argsopen = 1; 89 SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, ""); 90 91 void print_execve_args(struct image_args *args); 92 int debug_execve_args = 0; 93 SYSCTL_INT(_kern, OID_AUTO, debug_execve_args, CTLFLAG_RW, &debug_execve_args, 94 0, ""); 95 96 void 97 print_execve_args(struct image_args *args) 98 { 99 char *cp; 100 int ndx; 101 102 cp = args->begin_argv; 103 for (ndx = 0; ndx < args->argc; ndx++) { 104 printf("\targv[%d]: %s\n", ndx, cp); 105 while (*cp++ != '\0'); 106 } 107 for (ndx = 0; ndx < args->envc; ndx++) { 108 printf("\tenvv[%d]: %s\n", ndx, cp); 109 while (*cp++ != '\0'); 110 } 111 } 112 113 /* 114 * Each of the items is a pointer to a `const struct execsw', hence the 115 * double pointer here. 116 */ 117 static const struct execsw **execsw; 118 119 int 120 kern_execve(struct nlookupdata *nd, struct image_args *args) 121 { 122 struct thread *td = curthread; 123 struct proc *p = td->td_proc; 124 register_t *stack_base; 125 int error, len, i; 126 struct image_params image_params, *imgp; 127 struct vattr attr; 128 int (*img_first) (struct image_params *); 129 130 if (debug_execve_args) { 131 printf("%s()\n", __func__); 132 print_execve_args(args); 133 } 134 135 KKASSERT(p); 136 imgp = &image_params; 137 138 /* 139 * Lock the process and set the P_INEXEC flag to indicate that 140 * it should be left alone until we're done here. This is 141 * necessary to avoid race conditions - e.g. in ptrace() - 142 * that might allow a local user to illicitly obtain elevated 143 * privileges. 144 */ 145 p->p_flag |= P_INEXEC; 146 147 /* 148 * Initialize part of the common data 149 */ 150 imgp->proc = p; 151 imgp->args = args; 152 imgp->attr = &attr; 153 imgp->entry_addr = 0; 154 imgp->resident = 0; 155 imgp->vmspace_destroyed = 0; 156 imgp->interpreted = 0; 157 imgp->interpreter_name[0] = 0; 158 imgp->auxargs = NULL; 159 imgp->vp = NULL; 160 imgp->firstpage = NULL; 161 imgp->ps_strings = 0; 162 imgp->image_header = NULL; 163 164 interpret: 165 166 /* 167 * Translate the file name to a vnode. Unlock the cache entry to 168 * improve parallelism for programs exec'd in parallel. 169 */ 170 if ((error = nlookup(nd)) != 0) 171 goto exec_fail; 172 error = cache_vget(nd->nl_ncp, nd->nl_cred, LK_EXCLUSIVE, &imgp->vp); 173 KKASSERT(nd->nl_flags & NLC_NCPISLOCKED); 174 nd->nl_flags &= ~NLC_NCPISLOCKED; 175 cache_unlock(nd->nl_ncp); 176 if (error) 177 goto exec_fail; 178 179 /* 180 * Check file permissions (also 'opens' file) 181 */ 182 error = exec_check_permissions(imgp); 183 if (error) { 184 VOP_UNLOCK(imgp->vp, 0, td); 185 goto exec_fail_dealloc; 186 } 187 188 error = exec_map_first_page(imgp); 189 VOP_UNLOCK(imgp->vp, 0, td); 190 if (error) 191 goto exec_fail_dealloc; 192 193 if (debug_execve_args && imgp->interpreted) { 194 printf(" target is interpreted -- recursive pass\n"); 195 printf(" interpreter: %s\n", imgp->interpreter_name); 196 print_execve_args(args); 197 } 198 199 /* 200 * If the current process has a special image activator it 201 * wants to try first, call it. For example, emulating shell 202 * scripts differently. 203 */ 204 error = -1; 205 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 206 error = img_first(imgp); 207 208 /* 209 * If the vnode has a registered vmspace, exec the vmspace 210 */ 211 if (error == -1 && imgp->vp->v_resident) { 212 error = exec_resident_imgact(imgp); 213 } 214 215 /* 216 * Loop through the list of image activators, calling each one. 217 * An activator returns -1 if there is no match, 0 on success, 218 * and an error otherwise. 219 */ 220 for (i = 0; error == -1 && execsw[i]; ++i) { 221 if (execsw[i]->ex_imgact == NULL || 222 execsw[i]->ex_imgact == img_first) { 223 continue; 224 } 225 error = (*execsw[i]->ex_imgact)(imgp); 226 } 227 228 if (error) { 229 if (error == -1) 230 error = ENOEXEC; 231 goto exec_fail_dealloc; 232 } 233 234 /* 235 * Special interpreter operation, cleanup and loop up to try to 236 * activate the interpreter. 237 */ 238 if (imgp->interpreted) { 239 exec_unmap_first_page(imgp); 240 nlookup_done(nd); 241 vrele(imgp->vp); 242 imgp->vp = NULL; 243 error = nlookup_init(nd, imgp->interpreter_name, UIO_SYSSPACE, 244 NLC_FOLLOW); 245 if (error) 246 goto exec_fail; 247 goto interpret; 248 } 249 250 /* 251 * Copy out strings (args and env) and initialize stack base 252 */ 253 stack_base = exec_copyout_strings(imgp); 254 p->p_vmspace->vm_minsaddr = (char *)stack_base; 255 256 /* 257 * If custom stack fixup routine present for this process 258 * let it do the stack setup. If we are running a resident 259 * image there is no auxinfo or other image activator context 260 * so don't try to add fixups to the stack. 261 * 262 * Else stuff argument count as first item on stack 263 */ 264 if (p->p_sysent->sv_fixup && imgp->resident == 0) 265 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 266 else 267 suword(--stack_base, imgp->args->argc); 268 269 /* 270 * For security and other reasons, the file descriptor table cannot 271 * be shared after an exec. 272 */ 273 if (p->p_fd->fd_refcnt > 1) { 274 struct filedesc *tmp; 275 276 tmp = fdcopy(p); 277 fdfree(p); 278 p->p_fd = tmp; 279 } 280 281 /* 282 * For security and other reasons, signal handlers cannot 283 * be shared after an exec. The new proces gets a copy of the old 284 * handlers. In execsigs(), the new process will have its signals 285 * reset. 286 */ 287 if (p->p_procsig->ps_refcnt > 1) { 288 struct procsig *newprocsig; 289 290 MALLOC(newprocsig, struct procsig *, sizeof(struct procsig), 291 M_SUBPROC, M_WAITOK); 292 bcopy(p->p_procsig, newprocsig, sizeof(*newprocsig)); 293 p->p_procsig->ps_refcnt--; 294 p->p_procsig = newprocsig; 295 p->p_procsig->ps_refcnt = 1; 296 if (p->p_sigacts == &p->p_addr->u_sigacts) 297 panic("shared procsig but private sigacts?"); 298 299 p->p_addr->u_sigacts = *p->p_sigacts; 300 p->p_sigacts = &p->p_addr->u_sigacts; 301 } 302 303 /* Stop profiling */ 304 stopprofclock(p); 305 306 /* close files on exec */ 307 fdcloseexec(p); 308 309 /* reset caught signals */ 310 execsigs(p); 311 312 /* name this process - nameiexec(p, ndp) */ 313 len = min(nd->nl_ncp->nc_nlen, MAXCOMLEN); 314 bcopy(nd->nl_ncp->nc_name, p->p_comm, len); 315 p->p_comm[len] = 0; 316 317 /* 318 * mark as execed, wakeup the process that vforked (if any) and tell 319 * it that it now has its own resources back 320 */ 321 p->p_flag |= P_EXEC; 322 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 323 p->p_flag &= ~P_PPWAIT; 324 wakeup((caddr_t)p->p_pptr); 325 } 326 327 /* 328 * Implement image setuid/setgid. 329 * 330 * Don't honor setuid/setgid if the filesystem prohibits it or if 331 * the process is being traced. 332 */ 333 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 334 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 335 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 336 (p->p_flag & P_TRACED) == 0) { 337 /* 338 * Turn off syscall tracing for set-id programs, except for 339 * root. Record any set-id flags first to make sure that 340 * we do not regain any tracing during a possible block. 341 */ 342 setsugid(); 343 if (p->p_tracep && suser(td)) { 344 struct vnode *vtmp; 345 346 if ((vtmp = p->p_tracep) != NULL) { 347 p->p_tracep = NULL; 348 p->p_traceflag = 0; 349 vrele(vtmp); 350 } 351 } 352 /* Close any file descriptors 0..2 that reference procfs */ 353 setugidsafety(p); 354 /* Make sure file descriptors 0..2 are in use. */ 355 error = fdcheckstd(p); 356 if (error != 0) 357 goto exec_fail_dealloc; 358 /* 359 * Set the new credentials. 360 */ 361 cratom(&p->p_ucred); 362 if (attr.va_mode & VSUID) 363 change_euid(attr.va_uid); 364 if (attr.va_mode & VSGID) 365 p->p_ucred->cr_gid = attr.va_gid; 366 367 /* 368 * Clear local varsym variables 369 */ 370 varsymset_clean(&p->p_varsymset); 371 } else { 372 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && 373 p->p_ucred->cr_gid == p->p_ucred->cr_rgid) 374 p->p_flag &= ~P_SUGID; 375 } 376 377 /* 378 * Implement correct POSIX saved-id behavior. 379 */ 380 if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || 381 p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { 382 cratom(&p->p_ucred); 383 p->p_ucred->cr_svuid = p->p_ucred->cr_uid; 384 p->p_ucred->cr_svgid = p->p_ucred->cr_gid; 385 } 386 387 /* 388 * Store the vp for use in procfs 389 */ 390 if (p->p_textvp) /* release old reference */ 391 vrele(p->p_textvp); 392 p->p_textvp = imgp->vp; 393 vref(p->p_textvp); 394 395 /* 396 * Notify others that we exec'd, and clear the P_INEXEC flag 397 * as we're now a bona fide freshly-execed process. 398 */ 399 KNOTE(&p->p_klist, NOTE_EXEC); 400 p->p_flag &= ~P_INEXEC; 401 402 /* 403 * If tracing the process, trap to debugger so breakpoints 404 * can be set before the program executes. 405 */ 406 STOPEVENT(p, S_EXEC, 0); 407 408 if (p->p_flag & P_TRACED) 409 psignal(p, SIGTRAP); 410 411 /* clear "fork but no exec" flag, as we _are_ execing */ 412 p->p_acflag &= ~AFORK; 413 414 /* Set values passed into the program in registers. */ 415 setregs(p, imgp->entry_addr, (u_long)(uintptr_t)stack_base, 416 imgp->ps_strings); 417 418 /* Free any previous argument cache */ 419 if (p->p_args && --p->p_args->ar_ref == 0) 420 FREE(p->p_args, M_PARGS); 421 p->p_args = NULL; 422 423 /* Cache arguments if they fit inside our allowance */ 424 i = imgp->args->begin_envv - imgp->args->begin_argv; 425 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 426 MALLOC(p->p_args, struct pargs *, sizeof(struct pargs) + i, 427 M_PARGS, M_WAITOK); 428 p->p_args->ar_ref = 1; 429 p->p_args->ar_length = i; 430 bcopy(imgp->args->begin_argv, p->p_args->ar_args, i); 431 } 432 433 exec_fail_dealloc: 434 435 /* 436 * free various allocated resources 437 */ 438 if (imgp->firstpage) 439 exec_unmap_first_page(imgp); 440 441 if (imgp->vp) { 442 vrele(imgp->vp); 443 imgp->vp = NULL; 444 } 445 446 if (error == 0) { 447 ++mycpu->gd_cnt.v_exec; 448 return (0); 449 } 450 451 exec_fail: 452 /* we're done here, clear P_INEXEC */ 453 p->p_flag &= ~P_INEXEC; 454 if (imgp->vmspace_destroyed) { 455 /* sorry, no more process anymore. exit gracefully */ 456 exit1(W_EXITCODE(0, SIGABRT)); 457 /* NOT REACHED */ 458 return(0); 459 } else { 460 return(error); 461 } 462 } 463 464 /* 465 * execve() system call. 466 */ 467 int 468 execve(struct execve_args *uap) 469 { 470 struct nlookupdata nd; 471 struct image_args args; 472 int error; 473 474 error = nlookup_init(&nd, uap->fname, UIO_USERSPACE, NLC_FOLLOW); 475 if (error == 0) { 476 error = exec_copyin_args(&args, uap->fname, PATH_USERSPACE, 477 uap->argv, uap->envv); 478 } 479 if (error == 0) 480 error = kern_execve(&nd, &args); 481 nlookup_done(&nd); 482 exec_free_args(&args); 483 484 /* 485 * The syscall result is returned in registers to the new program. 486 * Linux will register %edx as an atexit function and we must be 487 * sure to set it to 0. XXX 488 */ 489 if (error == 0) 490 uap->sysmsg_result64 = 0; 491 492 return (error); 493 } 494 495 int 496 exec_map_first_page(struct image_params *imgp) 497 { 498 int rv, i; 499 int initial_pagein; 500 vm_page_t ma[VM_INITIAL_PAGEIN]; 501 vm_page_t m; 502 vm_object_t object; 503 int error; 504 505 if (imgp->firstpage) 506 exec_unmap_first_page(imgp); 507 508 /* 509 * XXX the callers should really use vn_open so we don't have to 510 * do this junk. 511 */ 512 if ((error = VOP_GETVOBJECT(imgp->vp, &object)) != 0) { 513 if (vn_canvmio(imgp->vp) == TRUE) { 514 error = vfs_object_create(imgp->vp, curthread); 515 if (error == 0) 516 error = VOP_GETVOBJECT(imgp->vp, &object); 517 } 518 } 519 if (error) 520 return (EIO); 521 522 /* 523 * We shouldn't need protection for vm_page_grab() but we certainly 524 * need it for the lookup loop below (lookup/busy race), since 525 * an interrupt can unbusy and free the page before our busy check. 526 */ 527 crit_enter(); 528 m = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 529 530 if ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 531 ma[0] = m; 532 initial_pagein = VM_INITIAL_PAGEIN; 533 if (initial_pagein > object->size) 534 initial_pagein = object->size; 535 for (i = 1; i < initial_pagein; i++) { 536 if ((m = vm_page_lookup(object, i)) != NULL) { 537 if ((m->flags & PG_BUSY) || m->busy) 538 break; 539 if (m->valid) 540 break; 541 vm_page_busy(m); 542 } else { 543 m = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 544 if (m == NULL) 545 break; 546 } 547 ma[i] = m; 548 } 549 initial_pagein = i; 550 551 /* 552 * get_pages unbusies all the requested pages except the 553 * primary page (at index 0 in this case). 554 */ 555 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 556 m = vm_page_lookup(object, 0); 557 558 if (rv != VM_PAGER_OK || m == NULL || m->valid == 0) { 559 if (m) { 560 vm_page_protect(m, VM_PROT_NONE); 561 vm_page_free(m); 562 } 563 crit_exit(); 564 return EIO; 565 } 566 } 567 vm_page_hold(m); 568 vm_page_wakeup(m); /* unbusy the page */ 569 crit_exit(); 570 571 imgp->firstpage = sf_buf_alloc(m, SFBA_QUICK); 572 imgp->image_header = (void *)sf_buf_kva(imgp->firstpage); 573 574 return 0; 575 } 576 577 void 578 exec_unmap_first_page(imgp) 579 struct image_params *imgp; 580 { 581 vm_page_t m; 582 583 crit_enter(); 584 if (imgp->firstpage != NULL) { 585 m = sf_buf_page(imgp->firstpage); 586 sf_buf_free(imgp->firstpage); 587 imgp->firstpage = NULL; 588 imgp->image_header = NULL; 589 vm_page_unhold(m); 590 } 591 crit_exit(); 592 } 593 594 /* 595 * Destroy old address space, and allocate a new stack 596 * The new stack is only SGROWSIZ large because it is grown 597 * automatically in trap.c. 598 */ 599 int 600 exec_new_vmspace(struct image_params *imgp, struct vmspace *vmcopy) 601 { 602 int error; 603 struct vmspace *vmspace = imgp->proc->p_vmspace; 604 vm_offset_t stack_addr = USRSTACK - maxssiz; 605 vm_map_t map; 606 607 imgp->vmspace_destroyed = 1; 608 609 /* 610 * Prevent a pending AIO from modifying the new address space. 611 */ 612 aio_proc_rundown(imgp->proc); 613 614 /* 615 * Blow away entire process VM, if address space not shared, 616 * otherwise, create a new VM space so that other threads are 617 * not disrupted. If we are execing a resident vmspace we 618 * create a duplicate of it and remap the stack. 619 * 620 * The exitingcnt test is not strictly necessary but has been 621 * included for code sanity (to make the code more deterministic). 622 */ 623 map = &vmspace->vm_map; 624 if (vmcopy) { 625 vmspace_exec(imgp->proc, vmcopy); 626 vmspace = imgp->proc->p_vmspace; 627 pmap_remove_pages(vmspace_pmap(vmspace), stack_addr, USRSTACK); 628 map = &vmspace->vm_map; 629 } else if (vmspace->vm_refcnt == 1 && vmspace->vm_exitingcnt == 0) { 630 shmexit(vmspace); 631 if (vmspace->vm_upcalls) 632 upc_release(vmspace, imgp->proc); 633 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); 634 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); 635 } else { 636 vmspace_exec(imgp->proc, NULL); 637 vmspace = imgp->proc->p_vmspace; 638 map = &vmspace->vm_map; 639 } 640 641 /* Allocate a new stack */ 642 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 643 VM_PROT_ALL, VM_PROT_ALL, 0); 644 if (error) 645 return (error); 646 647 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 648 * VM_STACK case, but they are still used to monitor the size of the 649 * process stack so we can check the stack rlimit. 650 */ 651 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 652 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 653 654 return(0); 655 } 656 657 /* 658 * Copy out argument and environment strings from the old process 659 * address space into the temporary string buffer. 660 */ 661 int 662 exec_copyin_args(struct image_args *args, char *fname, 663 enum exec_path_segflg segflg, char **argv, char **envv) 664 { 665 char *argp, *envp; 666 int error = 0; 667 size_t length; 668 669 bzero(args, sizeof(*args)); 670 args->buf = (char *) kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 671 if (args->buf == NULL) 672 return (ENOMEM); 673 args->begin_argv = args->buf; 674 args->endp = args->begin_argv; 675 args->space = ARG_MAX; 676 677 args->fname = args->buf + ARG_MAX; 678 679 /* 680 * Copy the file name. 681 */ 682 if (segflg == PATH_SYSSPACE) { 683 error = copystr(fname, args->fname, PATH_MAX, &length); 684 } else if (segflg == PATH_USERSPACE) { 685 error = copyinstr(fname, args->fname, PATH_MAX, &length); 686 } 687 688 /* 689 * extract argument strings 690 */ 691 692 if (argv && error == 0) { 693 /* 694 * The argv0 argument for execv() is allowed to be NULL, 695 * in which case we use our filename as argv[0]. 696 * This guarantees that 697 * the interpreter knows what file to open in the case 698 * that we exec an interpreted file. 699 */ 700 argp = (caddr_t) (intptr_t) fuword(argv); 701 if (argp == NULL) { 702 length = strlen(args->fname) + 1; 703 KKASSERT(length <= args->space); 704 bcopy(args->fname, args->endp, length); 705 args->space -= length; 706 args->endp += length; 707 args->argc++; 708 argv++; 709 } 710 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 711 if (argp == (caddr_t) -1) { 712 error = EFAULT; 713 goto cleanup; 714 } 715 error = copyinstr(argp, args->endp, 716 args->space, &length); 717 if (error == ENAMETOOLONG) 718 error = E2BIG; 719 if (error) 720 goto cleanup; 721 args->space -= length; 722 args->endp += length; 723 args->argc++; 724 } 725 } 726 727 args->begin_envv = args->endp; 728 729 /* 730 * extract environment strings 731 */ 732 if (envv && error == 0) { 733 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 734 if (envp == (caddr_t) -1) { 735 error = EFAULT; 736 goto cleanup; 737 } 738 error = copyinstr(envp, args->endp, args->space, 739 &length); 740 if (error == ENAMETOOLONG) 741 error = E2BIG; 742 if (error) 743 goto cleanup; 744 args->space -= length; 745 args->endp += length; 746 args->envc++; 747 } 748 } 749 750 cleanup: 751 return (error); 752 } 753 754 void 755 exec_free_args(struct image_args *args) 756 { 757 if (args->buf) { 758 kmem_free_wakeup(exec_map, 759 (vm_offset_t)args->buf, PATH_MAX + ARG_MAX); 760 args->buf = NULL; 761 } 762 } 763 764 /* 765 * Copy strings out to the new process address space, constructing 766 * new arg and env vector tables. Return a pointer to the base 767 * so that it can be used as the initial stack pointer. 768 */ 769 register_t * 770 exec_copyout_strings(struct image_params *imgp) 771 { 772 int argc, envc; 773 char **vectp; 774 char *stringp, *destp; 775 register_t *stack_base; 776 struct ps_strings *arginfo; 777 int szsigcode; 778 779 /* 780 * Calculate string base and vector table pointers. 781 * Also deal with signal trampoline code for this exec type. 782 */ 783 arginfo = (struct ps_strings *)PS_STRINGS; 784 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 785 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 786 roundup((ARG_MAX - imgp->args->space), sizeof(char *)); 787 788 /* 789 * install sigcode 790 */ 791 if (szsigcode) 792 copyout(imgp->proc->p_sysent->sv_sigcode, 793 ((caddr_t)arginfo - szsigcode), szsigcode); 794 795 /* 796 * If we have a valid auxargs ptr, prepare some room 797 * on the stack. 798 * 799 * The '+ 2' is for the null pointers at the end of each of the 800 * arg and env vector sets, and 'AT_COUNT*2' is room for the 801 * ELF Auxargs data. 802 */ 803 if (imgp->auxargs) { 804 vectp = (char **)(destp - (imgp->args->argc + 805 imgp->args->envc + 2 + AT_COUNT * 2) * sizeof(char*)); 806 } else { 807 vectp = (char **)(destp - (imgp->args->argc + 808 imgp->args->envc + 2) * sizeof(char*)); 809 } 810 811 /* 812 * NOTE: don't bother aligning the stack here for GCC 2.x, it will 813 * be done in crt1.o. Note that GCC 3.x aligns the stack in main. 814 */ 815 816 /* 817 * vectp also becomes our initial stack base 818 */ 819 stack_base = (register_t *)vectp; 820 821 stringp = imgp->args->begin_argv; 822 argc = imgp->args->argc; 823 envc = imgp->args->envc; 824 825 /* 826 * Copy out strings - arguments and environment. 827 */ 828 copyout(stringp, destp, ARG_MAX - imgp->args->space); 829 830 /* 831 * Fill in "ps_strings" struct for ps, w, etc. 832 */ 833 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 834 suword(&arginfo->ps_nargvstr, argc); 835 836 /* 837 * Fill in argument portion of vector table. 838 */ 839 for (; argc > 0; --argc) { 840 suword(vectp++, (long)(intptr_t)destp); 841 while (*stringp++ != 0) 842 destp++; 843 destp++; 844 } 845 846 /* a null vector table pointer separates the argp's from the envp's */ 847 suword(vectp++, 0); 848 849 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 850 suword(&arginfo->ps_nenvstr, envc); 851 852 /* 853 * Fill in environment portion of vector table. 854 */ 855 for (; envc > 0; --envc) { 856 suword(vectp++, (long)(intptr_t)destp); 857 while (*stringp++ != 0) 858 destp++; 859 destp++; 860 } 861 862 /* end of vector table is a null pointer */ 863 suword(vectp, 0); 864 865 return (stack_base); 866 } 867 868 /* 869 * Check permissions of file to execute. 870 * Return 0 for success or error code on failure. 871 */ 872 int 873 exec_check_permissions(imgp) 874 struct image_params *imgp; 875 { 876 struct proc *p = imgp->proc; 877 struct vnode *vp = imgp->vp; 878 struct vattr *attr = imgp->attr; 879 struct thread *td = p->p_thread; 880 int error; 881 882 /* Get file attributes */ 883 error = VOP_GETATTR(vp, attr, td); 884 if (error) 885 return (error); 886 887 /* 888 * 1) Check if file execution is disabled for the filesystem that this 889 * file resides on. 890 * 2) Insure that at least one execute bit is on - otherwise root 891 * will always succeed, and we don't want to happen unless the 892 * file really is executable. 893 * 3) Insure that the file is a regular file. 894 */ 895 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 896 ((attr->va_mode & 0111) == 0) || 897 (attr->va_type != VREG)) { 898 return (EACCES); 899 } 900 901 /* 902 * Zero length files can't be exec'd 903 */ 904 if (attr->va_size == 0) 905 return (ENOEXEC); 906 907 /* 908 * Check for execute permission to file based on current credentials. 909 */ 910 error = VOP_ACCESS(vp, VEXEC, p->p_ucred, td); 911 if (error) 912 return (error); 913 914 /* 915 * Check number of open-for-writes on the file and deny execution 916 * if there are any. 917 */ 918 if (vp->v_writecount) 919 return (ETXTBSY); 920 921 /* 922 * Call filesystem specific open routine (which does nothing in the 923 * general case). 924 */ 925 error = VOP_OPEN(vp, FREAD, p->p_ucred, NULL, td); 926 if (error) 927 return (error); 928 929 return (0); 930 } 931 932 /* 933 * Exec handler registration 934 */ 935 int 936 exec_register(execsw_arg) 937 const struct execsw *execsw_arg; 938 { 939 const struct execsw **es, **xs, **newexecsw; 940 int count = 2; /* New slot and trailing NULL */ 941 942 if (execsw) 943 for (es = execsw; *es; es++) 944 count++; 945 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 946 if (newexecsw == NULL) 947 return ENOMEM; 948 xs = newexecsw; 949 if (execsw) 950 for (es = execsw; *es; es++) 951 *xs++ = *es; 952 *xs++ = execsw_arg; 953 *xs = NULL; 954 if (execsw) 955 free(execsw, M_TEMP); 956 execsw = newexecsw; 957 return 0; 958 } 959 960 int 961 exec_unregister(execsw_arg) 962 const struct execsw *execsw_arg; 963 { 964 const struct execsw **es, **xs, **newexecsw; 965 int count = 1; 966 967 if (execsw == NULL) 968 panic("unregister with no handlers left?"); 969 970 for (es = execsw; *es; es++) { 971 if (*es == execsw_arg) 972 break; 973 } 974 if (*es == NULL) 975 return ENOENT; 976 for (es = execsw; *es; es++) 977 if (*es != execsw_arg) 978 count++; 979 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 980 if (newexecsw == NULL) 981 return ENOMEM; 982 xs = newexecsw; 983 for (es = execsw; *es; es++) 984 if (*es != execsw_arg) 985 *xs++ = *es; 986 *xs = NULL; 987 if (execsw) 988 free(execsw, M_TEMP); 989 execsw = newexecsw; 990 return 0; 991 } 992