1 /* 2 * Copyright (c) 1993, David Greenman 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD$ 27 */ 28 29 #include <sys/param.h> 30 #include <sys/systm.h> 31 #include <sys/lock.h> 32 #include <sys/mutex.h> 33 #include <sys/sysproto.h> 34 #include <sys/signalvar.h> 35 #include <sys/kernel.h> 36 #include <sys/mount.h> 37 #include <sys/filedesc.h> 38 #include <sys/fcntl.h> 39 #include <sys/acct.h> 40 #include <sys/exec.h> 41 #include <sys/imgact.h> 42 #include <sys/imgact_elf.h> 43 #include <sys/wait.h> 44 #include <sys/malloc.h> 45 #include <sys/proc.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/user.h> 52 #include <sys/vnode.h> 53 54 #include <vm/vm.h> 55 #include <vm/vm_param.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 <machine/reg.h> 65 66 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 67 68 static MALLOC_DEFINE(M_ATEXEC, "atexec", "atexec callback"); 69 70 /* 71 * callout list for things to do at exec time 72 */ 73 struct execlist { 74 execlist_fn function; 75 TAILQ_ENTRY(execlist) next; 76 }; 77 78 TAILQ_HEAD(exec_list_head, execlist); 79 static struct exec_list_head exec_list = TAILQ_HEAD_INITIALIZER(exec_list); 80 81 static register_t *exec_copyout_strings(struct image_params *); 82 83 /* XXX This should be vm_size_t. */ 84 static u_long ps_strings = PS_STRINGS; 85 SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, ""); 86 87 /* XXX This should be vm_size_t. */ 88 static u_long usrstack = USRSTACK; 89 SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, ""); 90 91 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 92 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 93 &ps_arg_cache_limit, 0, ""); 94 95 int ps_argsopen = 1; 96 SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, ""); 97 98 #ifdef __ia64__ 99 /* XXX HACK */ 100 static int regstkpages = 256; 101 SYSCTL_INT(_machdep, OID_AUTO, regstkpages, CTLFLAG_RW, ®stkpages, 0, ""); 102 #endif 103 104 /* 105 * Each of the items is a pointer to a `const struct execsw', hence the 106 * double pointer here. 107 */ 108 static const struct execsw **execsw; 109 110 #ifndef _SYS_SYSPROTO_H_ 111 struct execve_args { 112 char *fname; 113 char **argv; 114 char **envv; 115 }; 116 #endif 117 118 /* 119 * execve() system call. 120 * 121 * MPSAFE 122 */ 123 int 124 execve(td, uap) 125 struct thread *td; 126 register struct execve_args *uap; 127 { 128 struct proc *p = td->td_proc; 129 struct nameidata nd, *ndp; 130 struct ucred *newcred = NULL, *oldcred; 131 struct uidinfo *euip; 132 register_t *stack_base; 133 int error, len, i; 134 struct image_params image_params, *imgp; 135 struct vattr attr; 136 int (*img_first)(struct image_params *); 137 struct pargs *oldargs, *newargs = NULL; 138 struct procsig *oldprocsig, *newprocsig; 139 #ifdef KTRACE 140 struct vnode *tracevp = NULL; 141 #endif 142 struct vnode *textvp = NULL; 143 144 imgp = &image_params; 145 146 /* 147 * Lock the process and set the P_INEXEC flag to indicate that 148 * it should be left alone until we're done here. This is 149 * necessary to avoid race conditions - e.g. in ptrace() - 150 * that might allow a local user to illicitly obtain elevated 151 * privileges. 152 */ 153 mtx_lock(&Giant); 154 PROC_LOCK(p); 155 KASSERT((p->p_flag & P_INEXEC) == 0, 156 ("%s(): process already has P_INEXEC flag", __func__)); 157 p->p_flag |= P_INEXEC; 158 PROC_UNLOCK(p); 159 160 /* XXXKSE */ 161 /* !!!!!!!! we need abort all the other threads of this process before we */ 162 /* proceed beyond his point! */ 163 164 /* 165 * Initialize part of the common data 166 */ 167 imgp->proc = p; 168 imgp->uap = uap; 169 imgp->attr = &attr; 170 imgp->argc = imgp->envc = 0; 171 imgp->argv0 = NULL; 172 imgp->entry_addr = 0; 173 imgp->vmspace_destroyed = 0; 174 imgp->interpreted = 0; 175 imgp->interpreter_name[0] = '\0'; 176 imgp->auxargs = NULL; 177 imgp->vp = NULL; 178 imgp->firstpage = NULL; 179 imgp->ps_strings = 0; 180 imgp->auxarg_size = 0; 181 182 /* 183 * Allocate temporary demand zeroed space for argument and 184 * environment strings 185 */ 186 imgp->stringbase = (char *)kmem_alloc_wait(exec_map, ARG_MAX + PAGE_SIZE); 187 if (imgp->stringbase == NULL) { 188 error = ENOMEM; 189 goto exec_fail; 190 } 191 imgp->stringp = imgp->stringbase; 192 imgp->stringspace = ARG_MAX; 193 imgp->image_header = imgp->stringbase + ARG_MAX; 194 195 /* 196 * Translate the file name. namei() returns a vnode pointer 197 * in ni_vp amoung other things. 198 */ 199 ndp = &nd; 200 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 201 UIO_USERSPACE, uap->fname, td); 202 203 interpret: 204 205 error = namei(ndp); 206 if (error) { 207 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase, 208 ARG_MAX + PAGE_SIZE); 209 goto exec_fail; 210 } 211 212 imgp->vp = ndp->ni_vp; 213 imgp->fname = uap->fname; 214 215 /* 216 * Check file permissions (also 'opens' file) 217 */ 218 error = exec_check_permissions(imgp); 219 if (error) { 220 VOP_UNLOCK(imgp->vp, 0, td); 221 goto exec_fail_dealloc; 222 } 223 224 error = exec_map_first_page(imgp); 225 VOP_UNLOCK(imgp->vp, 0, td); 226 if (error) 227 goto exec_fail_dealloc; 228 229 /* 230 * If the current process has a special image activator it 231 * wants to try first, call it. For example, emulating shell 232 * scripts differently. 233 */ 234 error = -1; 235 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 236 error = img_first(imgp); 237 238 /* 239 * Loop through the list of image activators, calling each one. 240 * An activator returns -1 if there is no match, 0 on success, 241 * and an error otherwise. 242 */ 243 for (i = 0; error == -1 && execsw[i]; ++i) { 244 if (execsw[i]->ex_imgact == NULL || 245 execsw[i]->ex_imgact == img_first) { 246 continue; 247 } 248 error = (*execsw[i]->ex_imgact)(imgp); 249 } 250 251 if (error) { 252 if (error == -1) 253 error = ENOEXEC; 254 goto exec_fail_dealloc; 255 } 256 257 /* 258 * Special interpreter operation, cleanup and loop up to try to 259 * activate the interpreter. 260 */ 261 if (imgp->interpreted) { 262 exec_unmap_first_page(imgp); 263 /* free name buffer and old vnode */ 264 NDFREE(ndp, NDF_ONLY_PNBUF); 265 vrele(ndp->ni_vp); 266 /* set new name to that of the interpreter */ 267 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 268 UIO_SYSSPACE, imgp->interpreter_name, td); 269 goto interpret; 270 } 271 272 /* 273 * Copy out strings (args and env) and initialize stack base 274 */ 275 stack_base = exec_copyout_strings(imgp); 276 p->p_vmspace->vm_minsaddr = (char *)stack_base; 277 278 /* 279 * If custom stack fixup routine present for this process 280 * let it do the stack setup. 281 * Else stuff argument count as first item on stack 282 */ 283 if (p->p_sysent->sv_fixup) 284 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 285 else 286 suword(--stack_base, imgp->argc); 287 288 /* 289 * For security and other reasons, the file descriptor table cannot 290 * be shared after an exec. 291 */ 292 FILEDESC_LOCK(p->p_fd); 293 if (p->p_fd->fd_refcnt > 1) { 294 struct filedesc *tmp; 295 296 tmp = fdcopy(td); 297 FILEDESC_UNLOCK(p->p_fd); 298 fdfree(td); 299 p->p_fd = tmp; 300 } else 301 FILEDESC_UNLOCK(p->p_fd); 302 303 /* 304 * Malloc things before we need locks. 305 */ 306 newcred = crget(); 307 euip = uifind(attr.va_uid); 308 i = imgp->endargs - imgp->stringbase; 309 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) 310 newargs = pargs_alloc(i); 311 312 /* close files on exec */ 313 fdcloseexec(td); 314 315 /* 316 * For security and other reasons, signal handlers cannot 317 * be shared after an exec. The new process gets a copy of the old 318 * handlers. In execsigs(), the new process will have its signals 319 * reset. 320 */ 321 PROC_LOCK(p); 322 mp_fixme("procsig needs a lock"); 323 if (p->p_procsig->ps_refcnt > 1) { 324 oldprocsig = p->p_procsig; 325 PROC_UNLOCK(p); 326 MALLOC(newprocsig, struct procsig *, sizeof(struct procsig), 327 M_SUBPROC, M_WAITOK); 328 bcopy(oldprocsig, newprocsig, sizeof(*newprocsig)); 329 newprocsig->ps_refcnt = 1; 330 oldprocsig->ps_refcnt--; 331 PROC_LOCK(p); 332 p->p_procsig = newprocsig; 333 if (p->p_sigacts == &p->p_uarea->u_sigacts) 334 panic("shared procsig but private sigacts?"); 335 336 p->p_uarea->u_sigacts = *p->p_sigacts; 337 p->p_sigacts = &p->p_uarea->u_sigacts; 338 } 339 /* Stop profiling */ 340 stopprofclock(p); 341 342 /* reset caught signals */ 343 execsigs(p); 344 345 /* name this process - nameiexec(p, ndp) */ 346 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 347 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 348 p->p_comm[len] = 0; 349 350 /* 351 * mark as execed, wakeup the process that vforked (if any) and tell 352 * it that it now has its own resources back 353 */ 354 p->p_flag |= P_EXEC; 355 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 356 p->p_flag &= ~P_PPWAIT; 357 wakeup((caddr_t)p->p_pptr); 358 } 359 360 /* 361 * Implement image setuid/setgid. 362 * 363 * Don't honor setuid/setgid if the filesystem prohibits it or if 364 * the process is being traced. 365 */ 366 oldcred = p->p_ucred; 367 if ((((attr.va_mode & VSUID) && oldcred->cr_uid != attr.va_uid) || 368 ((attr.va_mode & VSGID) && oldcred->cr_gid != attr.va_gid)) && 369 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 370 (p->p_flag & P_TRACED) == 0) { 371 /* 372 * Turn off syscall tracing for set-id programs, except for 373 * root. Record any set-id flags first to make sure that 374 * we do not regain any tracing during a possible block. 375 */ 376 setsugid(p); 377 #ifdef KTRACE 378 if (p->p_tracep && suser_cred(oldcred, PRISON_ROOT)) { 379 mtx_lock(&ktrace_mtx); 380 p->p_traceflag = 0; 381 tracevp = p->p_tracep; 382 p->p_tracep = NULL; 383 mtx_unlock(&ktrace_mtx); 384 } 385 #endif 386 /* Make sure file descriptors 0..2 are in use. */ 387 error = fdcheckstd(td); 388 if (error != 0) 389 goto exec_fail_dealloc; 390 /* 391 * Set the new credentials. 392 */ 393 crcopy(newcred, oldcred); 394 if (attr.va_mode & VSUID) 395 change_euid(newcred, euip); 396 if (attr.va_mode & VSGID) 397 change_egid(newcred, attr.va_gid); 398 setugidsafety(td); 399 /* 400 * Implement correct POSIX saved-id behavior. 401 */ 402 change_svuid(newcred, newcred->cr_uid); 403 change_svgid(newcred, newcred->cr_gid); 404 p->p_ucred = newcred; 405 newcred = NULL; 406 } else { 407 if (oldcred->cr_uid == oldcred->cr_ruid && 408 oldcred->cr_gid == oldcred->cr_rgid) 409 p->p_flag &= ~P_SUGID; 410 /* 411 * Implement correct POSIX saved-id behavior. 412 * 413 * XXX: It's not clear that the existing behavior is 414 * POSIX-compliant. A number of sources indicate that the 415 * saved uid/gid should only be updated if the new ruid is 416 * not equal to the old ruid, or the new euid is not equal 417 * to the old euid and the new euid is not equal to the old 418 * ruid. The FreeBSD code always updates the saved uid/gid. 419 * Also, this code uses the new (replaced) euid and egid as 420 * the source, which may or may not be the right ones to use. 421 */ 422 if (oldcred->cr_svuid != oldcred->cr_uid || 423 oldcred->cr_svgid != oldcred->cr_gid) { 424 crcopy(newcred, oldcred); 425 change_svuid(newcred, newcred->cr_uid); 426 change_svgid(newcred, newcred->cr_gid); 427 p->p_ucred = newcred; 428 newcred = NULL; 429 } 430 } 431 432 /* 433 * Store the vp for use in procfs 434 */ 435 textvp = p->p_textvp; 436 VREF(ndp->ni_vp); 437 p->p_textvp = ndp->ni_vp; 438 439 /* 440 * Notify others that we exec'd, and clear the P_INEXEC flag 441 * as we're now a bona fide freshly-execed process. 442 */ 443 KNOTE(&p->p_klist, NOTE_EXEC); 444 p->p_flag &= ~P_INEXEC; 445 446 /* 447 * If tracing the process, trap to debugger so breakpoints 448 * can be set before the program executes. 449 */ 450 _STOPEVENT(p, S_EXEC, 0); 451 452 if (p->p_flag & P_TRACED) 453 psignal(p, SIGTRAP); 454 455 /* clear "fork but no exec" flag, as we _are_ execing */ 456 p->p_acflag &= ~AFORK; 457 458 /* Free any previous argument cache */ 459 oldargs = p->p_args; 460 p->p_args = NULL; 461 462 /* Set values passed into the program in registers. */ 463 setregs(td, imgp->entry_addr, (u_long)(uintptr_t)stack_base, 464 imgp->ps_strings); 465 466 /* Cache arguments if they fit inside our allowance */ 467 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 468 bcopy(imgp->stringbase, newargs->ar_args, i); 469 p->p_args = newargs; 470 newargs = NULL; 471 } 472 PROC_UNLOCK(p); 473 474 /* 475 * Free any resources malloc'd earlier that we didn't use. 476 */ 477 uifree(euip); 478 if (newcred == NULL) 479 crfree(oldcred); 480 else 481 crfree(newcred); 482 KASSERT(newargs == NULL, ("leaking p_args")); 483 /* 484 * Handle deferred decrement of ref counts. 485 */ 486 if (textvp != NULL) 487 vrele(textvp); 488 #ifdef KTRACE 489 if (tracevp != NULL) 490 vrele(tracevp); 491 #endif 492 pargs_drop(oldargs); 493 494 exec_fail_dealloc: 495 496 /* 497 * free various allocated resources 498 */ 499 if (imgp->firstpage) 500 exec_unmap_first_page(imgp); 501 502 if (imgp->stringbase != NULL) 503 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase, 504 ARG_MAX + PAGE_SIZE); 505 506 if (imgp->vp) { 507 NDFREE(ndp, NDF_ONLY_PNBUF); 508 vrele(imgp->vp); 509 } 510 511 if (error == 0) 512 goto done2; 513 514 exec_fail: 515 /* we're done here, clear P_INEXEC */ 516 PROC_LOCK(p); 517 p->p_flag &= ~P_INEXEC; 518 PROC_UNLOCK(p); 519 520 if (imgp->vmspace_destroyed) { 521 /* sorry, no more process anymore. exit gracefully */ 522 exit1(td, W_EXITCODE(0, SIGABRT)); 523 /* NOT REACHED */ 524 error = 0; 525 } 526 done2: 527 mtx_unlock(&Giant); 528 return (error); 529 } 530 531 int 532 exec_map_first_page(imgp) 533 struct image_params *imgp; 534 { 535 int rv, i; 536 int initial_pagein; 537 vm_page_t ma[VM_INITIAL_PAGEIN]; 538 vm_object_t object; 539 540 GIANT_REQUIRED; 541 542 if (imgp->firstpage) { 543 exec_unmap_first_page(imgp); 544 } 545 546 VOP_GETVOBJECT(imgp->vp, &object); 547 548 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 549 550 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 551 initial_pagein = VM_INITIAL_PAGEIN; 552 if (initial_pagein > object->size) 553 initial_pagein = object->size; 554 for (i = 1; i < initial_pagein; i++) { 555 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 556 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy) 557 break; 558 if (ma[i]->valid) 559 break; 560 vm_page_busy(ma[i]); 561 } else { 562 ma[i] = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 563 if (ma[i] == NULL) 564 break; 565 } 566 } 567 initial_pagein = i; 568 569 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 570 ma[0] = vm_page_lookup(object, 0); 571 572 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || (ma[0]->valid == 0)) { 573 if (ma[0]) { 574 vm_page_protect(ma[0], VM_PROT_NONE); 575 vm_page_free(ma[0]); 576 } 577 return EIO; 578 } 579 } 580 581 vm_page_wire(ma[0]); 582 vm_page_wakeup(ma[0]); 583 584 pmap_qenter((vm_offset_t)imgp->image_header, ma, 1); 585 imgp->firstpage = ma[0]; 586 587 return 0; 588 } 589 590 void 591 exec_unmap_first_page(imgp) 592 struct image_params *imgp; 593 { 594 GIANT_REQUIRED; 595 596 if (imgp->firstpage) { 597 pmap_qremove((vm_offset_t)imgp->image_header, 1); 598 vm_page_unwire(imgp->firstpage, 1); 599 imgp->firstpage = NULL; 600 } 601 } 602 603 /* 604 * Destroy old address space, and allocate a new stack 605 * The new stack is only SGROWSIZ large because it is grown 606 * automatically in trap.c. 607 */ 608 int 609 exec_new_vmspace(imgp) 610 struct image_params *imgp; 611 { 612 int error; 613 struct execlist *ep; 614 struct proc *p = imgp->proc; 615 struct vmspace *vmspace = p->p_vmspace; 616 vm_offset_t stack_addr = USRSTACK - maxssiz; 617 618 GIANT_REQUIRED; 619 620 imgp->vmspace_destroyed = 1; 621 622 /* 623 * Perform functions registered with at_exec(). 624 */ 625 TAILQ_FOREACH(ep, &exec_list, next) 626 (*ep->function)(p); 627 628 /* 629 * Blow away entire process VM, if address space not shared, 630 * otherwise, create a new VM space so that other threads are 631 * not disrupted 632 */ 633 if (vmspace->vm_refcnt == 1) { 634 if (vmspace->vm_shm) 635 shmexit(p); 636 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); 637 vm_map_remove(&vmspace->vm_map, 0, VM_MAXUSER_ADDRESS); 638 } else { 639 vmspace_exec(p); 640 vmspace = p->p_vmspace; 641 } 642 643 /* Allocate a new stack */ 644 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 645 VM_PROT_ALL, VM_PROT_ALL, 0); 646 if (error) 647 return (error); 648 649 #ifdef __ia64__ 650 { 651 /* 652 * Allocate backing store. We really need something 653 * similar to vm_map_stack which can allow the backing 654 * store to grow upwards. This will do for now. 655 */ 656 vm_offset_t bsaddr; 657 bsaddr = USRSTACK - 2*maxssiz; 658 error = vm_map_find(&vmspace->vm_map, 0, 0, &bsaddr, 659 regstkpages * PAGE_SIZE, 0, 660 VM_PROT_ALL, VM_PROT_ALL, 0); 661 FIRST_THREAD_IN_PROC(p)->td_md.md_bspstore = bsaddr; 662 } 663 #endif 664 665 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 666 * VM_STACK case, but they are still used to monitor the size of the 667 * process stack so we can check the stack rlimit. 668 */ 669 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 670 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 671 672 return(0); 673 } 674 675 /* 676 * Copy out argument and environment strings from the old process 677 * address space into the temporary string buffer. 678 */ 679 int 680 exec_extract_strings(imgp) 681 struct image_params *imgp; 682 { 683 char **argv, **envv; 684 char *argp, *envp; 685 int error; 686 size_t length; 687 688 /* 689 * extract arguments first 690 */ 691 692 argv = imgp->uap->argv; 693 694 if (argv) { 695 argp = (caddr_t) (intptr_t) fuword(argv); 696 if (argp == (caddr_t) -1) 697 return (EFAULT); 698 if (argp) 699 argv++; 700 if (imgp->argv0) 701 argp = imgp->argv0; 702 if (argp) { 703 do { 704 if (argp == (caddr_t) -1) 705 return (EFAULT); 706 if ((error = copyinstr(argp, imgp->stringp, 707 imgp->stringspace, &length))) { 708 if (error == ENAMETOOLONG) 709 return(E2BIG); 710 return (error); 711 } 712 imgp->stringspace -= length; 713 imgp->stringp += length; 714 imgp->argc++; 715 } while ((argp = (caddr_t) (intptr_t) fuword(argv++))); 716 } 717 } 718 719 imgp->endargs = imgp->stringp; 720 721 /* 722 * extract environment strings 723 */ 724 725 envv = imgp->uap->envv; 726 727 if (envv) { 728 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 729 if (envp == (caddr_t) -1) 730 return (EFAULT); 731 if ((error = copyinstr(envp, imgp->stringp, 732 imgp->stringspace, &length))) { 733 if (error == ENAMETOOLONG) 734 return(E2BIG); 735 return (error); 736 } 737 imgp->stringspace -= length; 738 imgp->stringp += length; 739 imgp->envc++; 740 } 741 } 742 743 return (0); 744 } 745 746 /* 747 * Copy strings out to the new process address space, constructing 748 * new arg and env vector tables. Return a pointer to the base 749 * so that it can be used as the initial stack pointer. 750 */ 751 register_t * 752 exec_copyout_strings(imgp) 753 struct image_params *imgp; 754 { 755 int argc, envc; 756 char **vectp; 757 char *stringp, *destp; 758 register_t *stack_base; 759 struct ps_strings *arginfo; 760 int szsigcode; 761 762 /* 763 * Calculate string base and vector table pointers. 764 * Also deal with signal trampoline code for this exec type. 765 */ 766 arginfo = (struct ps_strings *)PS_STRINGS; 767 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 768 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 769 roundup((ARG_MAX - imgp->stringspace), sizeof(char *)); 770 771 /* 772 * install sigcode 773 */ 774 if (szsigcode) 775 copyout(imgp->proc->p_sysent->sv_sigcode, 776 ((caddr_t)arginfo - szsigcode), szsigcode); 777 778 /* 779 * If we have a valid auxargs ptr, prepare some room 780 * on the stack. 781 */ 782 if (imgp->auxargs) { 783 /* 784 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 785 * lower compatibility. 786 */ 787 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size 788 : (AT_COUNT * 2); 789 /* 790 * The '+ 2' is for the null pointers at the end of each of 791 * the arg and env vector sets,and imgp->auxarg_size is room 792 * for argument of Runtime loader. 793 */ 794 vectp = (char **) (destp - (imgp->argc + imgp->envc + 2 + 795 imgp->auxarg_size) * sizeof(char *)); 796 797 } else 798 /* 799 * The '+ 2' is for the null pointers at the end of each of 800 * the arg and env vector sets 801 */ 802 vectp = (char **) 803 (destp - (imgp->argc + imgp->envc + 2) * sizeof(char *)); 804 805 /* 806 * vectp also becomes our initial stack base 807 */ 808 stack_base = (register_t *)vectp; 809 810 stringp = imgp->stringbase; 811 argc = imgp->argc; 812 envc = imgp->envc; 813 814 /* 815 * Copy out strings - arguments and environment. 816 */ 817 copyout(stringp, destp, ARG_MAX - imgp->stringspace); 818 819 /* 820 * Fill in "ps_strings" struct for ps, w, etc. 821 */ 822 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 823 suword(&arginfo->ps_nargvstr, argc); 824 825 /* 826 * Fill in argument portion of vector table. 827 */ 828 for (; argc > 0; --argc) { 829 suword(vectp++, (long)(intptr_t)destp); 830 while (*stringp++ != 0) 831 destp++; 832 destp++; 833 } 834 835 /* a null vector table pointer separates the argp's from the envp's */ 836 suword(vectp++, 0); 837 838 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 839 suword(&arginfo->ps_nenvstr, envc); 840 841 /* 842 * Fill in environment portion of vector table. 843 */ 844 for (; envc > 0; --envc) { 845 suword(vectp++, (long)(intptr_t)destp); 846 while (*stringp++ != 0) 847 destp++; 848 destp++; 849 } 850 851 /* end of vector table is a null pointer */ 852 suword(vectp, 0); 853 854 return (stack_base); 855 } 856 857 /* 858 * Check permissions of file to execute. 859 * Called with imgp->vp locked. 860 * Return 0 for success or error code on failure. 861 */ 862 int 863 exec_check_permissions(imgp) 864 struct image_params *imgp; 865 { 866 struct vnode *vp = imgp->vp; 867 struct vattr *attr = imgp->attr; 868 struct thread *td; 869 int error; 870 871 td = curthread; /* XXXKSE */ 872 /* Get file attributes */ 873 error = VOP_GETATTR(vp, attr, td->td_ucred, td); 874 if (error) 875 return (error); 876 877 /* 878 * 1) Check if file execution is disabled for the filesystem that this 879 * file resides on. 880 * 2) Insure that at least one execute bit is on - otherwise root 881 * will always succeed, and we don't want to happen unless the 882 * file really is executable. 883 * 3) Insure that the file is a regular file. 884 */ 885 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 886 ((attr->va_mode & 0111) == 0) || 887 (attr->va_type != VREG)) 888 return (EACCES); 889 890 /* 891 * Zero length files can't be exec'd 892 */ 893 if (attr->va_size == 0) 894 return (ENOEXEC); 895 896 /* 897 * Check for execute permission to file based on current credentials. 898 */ 899 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 900 if (error) 901 return (error); 902 903 /* 904 * Check number of open-for-writes on the file and deny execution 905 * if there are any. 906 */ 907 if (vp->v_writecount) 908 return (ETXTBSY); 909 910 /* 911 * Call filesystem specific open routine (which does nothing in the 912 * general case). 913 */ 914 error = VOP_OPEN(vp, FREAD, td->td_ucred, td); 915 return (error); 916 } 917 918 /* 919 * Exec handler registration 920 */ 921 int 922 exec_register(execsw_arg) 923 const struct execsw *execsw_arg; 924 { 925 const struct execsw **es, **xs, **newexecsw; 926 int count = 2; /* New slot and trailing NULL */ 927 928 if (execsw) 929 for (es = execsw; *es; es++) 930 count++; 931 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 932 if (newexecsw == NULL) 933 return ENOMEM; 934 xs = newexecsw; 935 if (execsw) 936 for (es = execsw; *es; es++) 937 *xs++ = *es; 938 *xs++ = execsw_arg; 939 *xs = NULL; 940 if (execsw) 941 free(execsw, M_TEMP); 942 execsw = newexecsw; 943 return 0; 944 } 945 946 int 947 exec_unregister(execsw_arg) 948 const struct execsw *execsw_arg; 949 { 950 const struct execsw **es, **xs, **newexecsw; 951 int count = 1; 952 953 if (execsw == NULL) 954 panic("unregister with no handlers left?\n"); 955 956 for (es = execsw; *es; es++) { 957 if (*es == execsw_arg) 958 break; 959 } 960 if (*es == NULL) 961 return ENOENT; 962 for (es = execsw; *es; es++) 963 if (*es != execsw_arg) 964 count++; 965 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 966 if (newexecsw == NULL) 967 return ENOMEM; 968 xs = newexecsw; 969 for (es = execsw; *es; es++) 970 if (*es != execsw_arg) 971 *xs++ = *es; 972 *xs = NULL; 973 if (execsw) 974 free(execsw, M_TEMP); 975 execsw = newexecsw; 976 return 0; 977 } 978 979 int 980 at_exec(function) 981 execlist_fn function; 982 { 983 struct execlist *ep; 984 985 #ifdef INVARIANTS 986 /* Be noisy if the programmer has lost track of things */ 987 if (rm_at_exec(function)) 988 printf("WARNING: exec callout entry (%p) already present\n", 989 function); 990 #endif 991 ep = malloc(sizeof(*ep), M_ATEXEC, M_NOWAIT); 992 if (ep == NULL) 993 return (ENOMEM); 994 ep->function = function; 995 TAILQ_INSERT_TAIL(&exec_list, ep, next); 996 return (0); 997 } 998 999 /* 1000 * Scan the exec callout list for the given item and remove it. 1001 * Returns the number of items removed (0 or 1) 1002 */ 1003 int 1004 rm_at_exec(function) 1005 execlist_fn function; 1006 { 1007 struct execlist *ep; 1008 1009 TAILQ_FOREACH(ep, &exec_list, next) { 1010 if (ep->function == function) { 1011 TAILQ_REMOVE(&exec_list, ep, next); 1012 free(ep, M_ATEXEC); 1013 return(1); 1014 } 1015 } 1016 return (0); 1017 } 1018 1019