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 */ 28 29 #include <sys/param.h> 30 #include <sys/systm.h> 31 #include <sys/sysmsg.h> 32 #include <sys/kernel.h> 33 #include <sys/mount.h> 34 #include <sys/filedesc.h> 35 #include <sys/fcntl.h> 36 #include <sys/acct.h> 37 #include <sys/exec.h> 38 #include <sys/imgact.h> 39 #include <sys/imgact_elf.h> 40 #include <sys/kern_syscall.h> 41 #include <sys/wait.h> 42 #include <sys/malloc.h> 43 #include <sys/proc.h> 44 #include <sys/priv.h> 45 #include <sys/ktrace.h> 46 #include <sys/signalvar.h> 47 #include <sys/pioctl.h> 48 #include <sys/nlookup.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/libkern.h> 55 56 #include <cpu/lwbuf.h> 57 58 #include <vm/vm.h> 59 #include <vm/vm_param.h> 60 #include <sys/lock.h> 61 #include <vm/pmap.h> 62 #include <vm/vm_page.h> 63 #include <vm/vm_map.h> 64 #include <vm/vm_kern.h> 65 #include <vm/vm_extern.h> 66 #include <vm/vm_object.h> 67 #include <vm/vnode_pager.h> 68 #include <vm/vm_pager.h> 69 70 #include <sys/reg.h> 71 72 #include <sys/objcache.h> 73 #include <sys/refcount.h> 74 #include <sys/thread2.h> 75 #include <vm/vm_page2.h> 76 77 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 78 MALLOC_DEFINE(M_EXECARGS, "exec-args", "Exec arguments"); 79 80 enum exec_path_segflg { 81 PATH_SYSSPACE, 82 PATH_USERSPACE, 83 }; 84 85 static register_t *exec_copyout_strings(struct image_params *); 86 static int exec_copyin_args(struct image_args *, char *, 87 enum exec_path_segflg, char **, char **); 88 static void exec_free_args(struct image_args *); 89 static void print_execve_args(struct image_args *args); 90 91 /* XXX This should be vm_size_t. */ 92 __read_mostly static u_long ps_strings = PS_STRINGS; 93 SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, ""); 94 95 /* XXX This should be vm_size_t. */ 96 __read_mostly static u_long usrstack = USRSTACK; 97 SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, ""); 98 99 __read_mostly u_long ps_arg_cache_limit = PAGE_SIZE / 16; 100 SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 101 &ps_arg_cache_limit, 0, ""); 102 103 __read_mostly int ps_argsopen = 1; 104 SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, ""); 105 106 __read_mostly static int ktrace_suid = 0; 107 SYSCTL_INT(_kern, OID_AUTO, ktrace_suid, CTLFLAG_RW, &ktrace_suid, 0, ""); 108 109 __read_mostly static int debug_execve_args = 0; 110 SYSCTL_INT(_kern, OID_AUTO, debug_execve_args, CTLFLAG_RW, &debug_execve_args, 111 0, ""); 112 113 /* 114 * Exec arguments object cache 115 */ 116 __read_mostly static struct objcache *exec_objcache; 117 118 static 119 void 120 exec_objcache_init(void *arg __unused) 121 { 122 int cluster_limit; 123 size_t limsize; 124 125 /* 126 * Maximum number of concurrent execs. This can be limiting on 127 * systems with a lot of cpu cores but it also eats a significant 128 * amount of memory. 129 */ 130 cluster_limit = (ncpus < 16) ? 16 : ncpus; 131 limsize = kmem_lim_size(); 132 if (limsize > 7 * 1024) 133 cluster_limit *= 2; 134 if (limsize > 15 * 1024) 135 cluster_limit *= 2; 136 137 exec_objcache = objcache_create_mbacked( 138 M_EXECARGS, PATH_MAX + ARG_MAX, 139 cluster_limit, 8, 140 NULL, NULL, NULL); 141 } 142 SYSINIT(exec_objcache, SI_BOOT2_MACHDEP, SI_ORDER_ANY, exec_objcache_init, 0); 143 144 /* 145 * stackgap_random specifies if the stackgap should have a random size added 146 * to it. It must be a power of 2. If non-zero, the stack gap will be 147 * calculated as: ALIGN(karc4random() & (stackgap_random - 1)). 148 */ 149 __read_mostly static int stackgap_random = 1024; 150 151 static int 152 sysctl_kern_stackgap(SYSCTL_HANDLER_ARGS) 153 { 154 int error, new_val; 155 new_val = stackgap_random; 156 error = sysctl_handle_int(oidp, &new_val, 0, req); 157 if (error != 0 || req->newptr == NULL) 158 return (error); 159 if (new_val > 0 && ((new_val > 16 * PAGE_SIZE) || !powerof2(new_val))) 160 return (EINVAL); 161 stackgap_random = new_val; 162 163 return(0); 164 } 165 166 SYSCTL_PROC(_kern, OID_AUTO, stackgap_random, CTLFLAG_RW|CTLTYPE_INT, 167 0, 0, sysctl_kern_stackgap, "I", 168 "Max random stack gap (power of 2), static gap if negative"); 169 170 static void 171 print_execve_args(struct image_args *args) 172 { 173 char *cp; 174 int ndx; 175 176 cp = args->begin_argv; 177 for (ndx = 0; ndx < args->argc; ndx++) { 178 kprintf("\targv[%d]: %s\n", ndx, cp); 179 while (*cp++ != '\0'); 180 } 181 for (ndx = 0; ndx < args->envc; ndx++) { 182 kprintf("\tenvv[%d]: %s\n", ndx, cp); 183 while (*cp++ != '\0'); 184 } 185 } 186 187 /* 188 * Each of the items is a pointer to a `const struct execsw', hence the 189 * double pointer here. 190 */ 191 __read_mostly static const struct execsw **execsw; 192 193 /* 194 * Replace current vmspace with a new binary. 195 * Returns 0 on success, > 0 on recoverable error (use as errno). 196 * Returns -1 on lethal error which demands killing of the current 197 * process! 198 */ 199 int 200 kern_execve(struct nlookupdata *nd, struct file *fp, char fileflags, 201 struct image_args *args) 202 { 203 static const char *proctitle = "(execve)"; 204 register_t *stack_base; 205 struct thread *td = curthread; 206 struct lwp *lp = td->td_lwp; 207 struct proc *p = td->td_proc; 208 struct vnode *ovp; 209 struct pargs *pa; 210 struct sigacts *ops; 211 struct sigacts *nps; 212 struct image_params image_params, *imgp; 213 struct filedesc *fds; 214 struct nchandle *nch; 215 struct nlookupdata nd_interpreter; 216 struct vattr_lite lva; 217 int error, len, i; 218 int (*img_first) (struct image_params *); 219 220 if (debug_execve_args) { 221 kprintf("%s()\n", __func__); 222 print_execve_args(args); 223 } 224 225 KKASSERT(p); 226 lwkt_gettoken(&p->p_token); 227 imgp = &image_params; 228 229 /* 230 * NOTE: P_INEXEC is handled by exec_new_vmspace() now. We make 231 * no modifications to the process at all until we get there. 232 * 233 * Note that multiple threads may be trying to exec at the same 234 * time. exec_new_vmspace() handles that too. 235 */ 236 237 /* 238 * Initialize part of the common data 239 */ 240 imgp->proc = p; 241 imgp->args = args; 242 imgp->lvap = &lva; 243 imgp->entry_addr = 0; 244 imgp->resident = 0; 245 imgp->vmspace_destroyed = 0; 246 imgp->interpreted = 0; 247 imgp->interpreter_name[0] = 0; 248 imgp->auxargs = NULL; 249 imgp->vp = NULL; 250 imgp->firstpage = NULL; 251 imgp->ps_strings = 0; 252 imgp->execpath = imgp->freepath = NULL; 253 imgp->execpathp = 0; 254 imgp->image_header = NULL; 255 256 interpret: 257 258 if (nd) { 259 /* 260 * Translate the file name to a vnode. Unlock the cache 261 * entry to improve parallelism for programs exec'd in 262 * parallel. 263 */ 264 nch = &nd->nl_nch; 265 nd->nl_flags |= NLC_SHAREDLOCK; 266 if ((error = nlookup(nd)) != 0) 267 goto failed; 268 269 error = cache_vget(nch, nd->nl_cred, LK_SHARED, &imgp->vp); 270 KKASSERT(nd->nl_flags & NLC_NCPISLOCKED); 271 nd->nl_flags &= ~NLC_NCPISLOCKED; 272 cache_unlock(nch); 273 } else { 274 nch = &fp->f_nchandle; 275 imgp->vp = fp->f_data; 276 error = vget(imgp->vp, LK_SHARED); 277 } 278 if (error) { 279 imgp->vp = NULL; 280 goto failed; 281 } 282 283 /* 284 * Check file permissions (also 'opens' file). 285 * Include also the top level mount in the check. 286 */ 287 error = exec_check_permissions(imgp, nch->mount); 288 if (error) { 289 vn_unlock(imgp->vp); 290 goto failed; 291 } 292 293 error = exec_map_first_page(imgp); 294 vn_unlock(imgp->vp); 295 if (error) 296 goto failed; 297 298 imgp->proc->p_osrel = 0; 299 300 if (debug_execve_args && imgp->interpreted) { 301 kprintf(" target is interpreted -- recursive pass\n"); 302 kprintf(" interpreter: %s\n", imgp->interpreter_name); 303 print_execve_args(args); 304 } 305 306 /* 307 * If the current process has a special image activator it 308 * wants to try first, call it. For example, emulating shell 309 * scripts differently. 310 */ 311 error = -1; 312 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 313 error = img_first(imgp); 314 315 /* 316 * If the vnode has a registered vmspace, exec the vmspace 317 */ 318 if (error == -1 && imgp->vp->v_resident) 319 error = exec_resident_imgact(imgp); 320 321 /* 322 * Loop through the list of image activators, calling each one. 323 * An activator returns -1 if there is no match, 0 on success, 324 * and an error otherwise. 325 */ 326 for (i = 0; error == -1 && execsw[i]; ++i) { 327 if (execsw[i]->ex_imgact == NULL || 328 execsw[i]->ex_imgact == img_first) { 329 continue; 330 } 331 error = (*execsw[i]->ex_imgact)(imgp); 332 } 333 334 if (error) { 335 if (error == -1) 336 error = ENOEXEC; 337 goto failed; 338 } 339 340 /* 341 * Special interpreter operation, cleanup and loop up to try to 342 * activate the interpreter. 343 */ 344 if (imgp->interpreted) { 345 exec_unmap_first_page(imgp); 346 vrele(imgp->vp); 347 imgp->vp = NULL; 348 349 nd = &nd_interpreter; 350 error = nlookup_init(nd, imgp->interpreter_name, 351 UIO_SYSSPACE, NLC_FOLLOW); 352 if (error) 353 goto failed; 354 355 if (fp && (fileflags & UF_EXCLOSE)) { 356 /* 357 * Fexecve'ing an interpreted file opened with 358 * O_CLOEXEC flag, return ENOENT. 359 */ 360 error = ENOENT; 361 goto failed; 362 } 363 364 goto interpret; 365 } 366 367 /* 368 * Do the best to calculate the full path to the image file 369 */ 370 if (imgp->auxargs != NULL && 371 ((args->fname != NULL && args->fname[0] == '/') || 372 vn_fullpath(imgp->proc, imgp->vp, &imgp->execpath, 373 &imgp->freepath, 0) != 0)) 374 { 375 imgp->execpath = args->fname; 376 } 377 378 /* 379 * Copy out strings (args and env) and initialize stack base 380 */ 381 stack_base = exec_copyout_strings(imgp); 382 p->p_vmspace->vm_minsaddr = (char *)stack_base; 383 384 /* 385 * If custom stack fixup routine present for this process 386 * let it do the stack setup. If we are running a resident 387 * image there is no auxinfo or other image activator context 388 * so don't try to add fixups to the stack. 389 * 390 * Else stuff argument count as first item on stack 391 */ 392 if (p->p_sysent->sv_fixup && imgp->resident == 0) 393 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 394 else 395 suword64(--stack_base, imgp->args->argc); 396 397 /* 398 * For security and other reasons, the file descriptor table cannot 399 * be shared after an exec. 400 */ 401 if (p->p_fd->fd_refcnt > 1) { 402 if ((error = fdcopy(p, &fds)) != 0) 403 goto failed; 404 405 fdfree(p, fds); 406 } 407 408 /* 409 * For security and other reasons, signal handlers cannot 410 * be shared after an exec. The new proces gets a copy of the old 411 * handlers. In execsigs(), the new process will have its signals 412 * reset. 413 */ 414 ops = p->p_sigacts; 415 if (ops->ps_refcnt > 1) { 416 nps = kmalloc(sizeof(*nps), M_SUBPROC, M_WAITOK); 417 bcopy(ops, nps, sizeof(*nps)); 418 refcount_init(&nps->ps_refcnt, 1); 419 p->p_sigacts = nps; 420 if (refcount_release(&ops->ps_refcnt)) { 421 kfree(ops, M_SUBPROC); 422 ops = NULL; 423 } 424 } 425 426 /* 427 * Clean up shared pages, the new program will allocate fresh 428 * copies as needed. This is also for security purposes and 429 * to ensure (for example) that things like sys_lpmap->blockallsigs 430 * state is properly reset on exec. 431 */ 432 lwp_userunmap(lp); 433 proc_userunmap(p); 434 435 /* 436 * For security and other reasons virtual kernels cannot be 437 * inherited by an exec. This also allows a virtual kernel 438 * to fork/exec unrelated applications. 439 */ 440 if (p->p_vkernel) 441 vkernel_exit(p); 442 443 /* Stop profiling */ 444 stopprofclock(p); 445 446 /* close files on exec */ 447 fdcloseexec(p); 448 449 /* reset caught signals */ 450 execsigs(p); 451 452 /* name this process */ 453 if (nch->ncp) { 454 len = min(nch->ncp->nc_nlen, MAXCOMLEN); 455 bcopy(nch->ncp->nc_name, p->p_comm, len); 456 } else { 457 len = sizeof(proctitle) - 1; 458 bcopy(proctitle, p->p_comm, len); 459 } 460 p->p_comm[len] = 0; 461 bcopy(p->p_comm, lp->lwp_thread->td_comm, MAXCOMLEN+1); 462 463 /* 464 * mark as execed, wakeup the process that vforked (if any) and tell 465 * it that it now has its own resources back 466 * 467 * We are using the P_PPWAIT as an interlock so an atomic op is 468 * necessary to synchronize with the parent's cpu. 469 */ 470 p->p_flags |= P_EXEC; 471 if (p->p_pptr && (p->p_flags & P_PPWAIT)) { 472 if (p->p_pptr->p_upmap) 473 atomic_add_int(&p->p_pptr->p_upmap->invfork, -1); 474 atomic_clear_int(&p->p_flags, P_PPWAIT); 475 wakeup(p->p_pptr); 476 } 477 478 /* 479 * Implement image setuid/setgid. 480 * 481 * Don't honor setuid/setgid if the filesystem prohibits it or if 482 * the process is being traced. 483 */ 484 if ((((lva.va_mode & VSUID) && p->p_ucred->cr_uid != lva.va_uid) || 485 ((lva.va_mode & VSGID) && p->p_ucred->cr_gid != lva.va_gid)) && 486 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 487 (p->p_flags & P_TRACED) == 0) { 488 /* 489 * Turn off syscall tracing for set-id programs, except for 490 * root. Record any set-id flags first to make sure that 491 * we do not regain any tracing during a possible block. 492 */ 493 setsugid(); 494 if (p->p_tracenode && ktrace_suid == 0 && 495 priv_check(td, PRIV_ROOT) != 0) { 496 ktrdestroy(&p->p_tracenode); 497 p->p_traceflag = 0; 498 } 499 500 /* Clear any PROC_PDEATHSIG_CTL setting */ 501 p->p_deathsig = 0; 502 503 /* Close any file descriptors 0..2 that reference procfs */ 504 setugidsafety(p); 505 /* Make sure file descriptors 0..2 are in use. */ 506 error = fdcheckstd(lp); 507 if (error != 0) 508 goto failed; 509 510 /* 511 * Set the new credentials. 512 */ 513 cratom_proc(p); 514 if (lva.va_mode & VSUID) 515 change_euid(lva.va_uid); 516 if (lva.va_mode & VSGID) 517 p->p_ucred->cr_gid = lva.va_gid; 518 519 /* Clear local varsym variables */ 520 varsymset_clean(&p->p_varsymset); 521 } else { 522 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && 523 p->p_ucred->cr_gid == p->p_ucred->cr_rgid) 524 p->p_flags &= ~P_SUGID; 525 } 526 527 /* 528 * Implement correct POSIX saved-id behavior. 529 */ 530 if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || 531 p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { 532 cratom_proc(p); 533 p->p_ucred->cr_svuid = p->p_ucred->cr_uid; 534 p->p_ucred->cr_svgid = p->p_ucred->cr_gid; 535 } 536 537 /* 538 * Store the vp for use in procfs. Be sure to keep p_textvp 539 * consistent if we block during the switch-over. 540 */ 541 ovp = p->p_textvp; 542 vref(imgp->vp); /* ref new vp */ 543 p->p_textvp = imgp->vp; 544 if (ovp) /* release old vp */ 545 vrele(ovp); 546 547 /* Release old namecache handle to text file */ 548 if (p->p_textnch.ncp) 549 cache_drop(&p->p_textnch); 550 if (nch->mount) 551 cache_copy(nch, &p->p_textnch); 552 553 /* 554 * Notify others that we exec'd, and clear the P_INEXEC flag 555 * as we're now a bona fide freshly-execed process. 556 */ 557 KNOTE(&p->p_klist, NOTE_EXEC); 558 p->p_flags &= ~P_INEXEC; 559 if (p->p_stops) 560 wakeup(&p->p_stype); 561 562 /* 563 * If tracing the process, trap to debugger so breakpoints 564 * can be set before the program executes. 565 */ 566 STOPEVENT(p, S_EXEC, 0); 567 568 if (p->p_flags & P_TRACED) 569 ksignal(p, SIGTRAP); 570 571 /* clear "fork but no exec" flag, as we _are_ execing */ 572 p->p_acflag &= ~AFORK; 573 574 /* Set values passed into the program in registers. */ 575 exec_setregs(imgp->entry_addr, (u_long)(uintptr_t)stack_base, 576 imgp->ps_strings); 577 578 /* Set the access time on the vnode */ 579 vn_mark_atime(imgp->vp, td); 580 581 /* 582 * Free any previous argument cache 583 */ 584 pa = p->p_args; 585 p->p_args = NULL; 586 if (pa && refcount_release(&pa->ar_ref)) { 587 kfree(pa, M_PARGS); 588 pa = NULL; 589 } 590 591 /* 592 * Cache arguments if they fit inside our allowance 593 */ 594 i = imgp->args->begin_envv - imgp->args->begin_argv; 595 if (sizeof(struct pargs) + i <= ps_arg_cache_limit) { 596 pa = kmalloc(sizeof(struct pargs) + i, M_PARGS, M_WAITOK); 597 refcount_init(&pa->ar_ref, 1); 598 pa->ar_length = i; 599 bcopy(imgp->args->begin_argv, pa->ar_args, i); 600 KKASSERT(p->p_args == NULL); 601 p->p_args = pa; 602 } 603 604 failed: 605 606 /* 607 * free various allocated resources 608 */ 609 if (imgp->firstpage) 610 exec_unmap_first_page(imgp); 611 if (imgp->vp) 612 vrele(imgp->vp); 613 if (imgp->freepath) 614 kfree(imgp->freepath, M_TEMP); 615 if (nd == &nd_interpreter) 616 nlookup_done(nd); 617 618 if (error == 0) { 619 ++mycpu->gd_cnt.v_exec; 620 lwkt_reltoken(&p->p_token); 621 return (0); 622 } 623 624 /* 625 * we're done here, clear P_INEXEC if we were the ones that 626 * set it. Otherwise if vmspace_destroyed is still set we 627 * raced another thread and that thread is responsible for 628 * clearing it. 629 */ 630 if (imgp->vmspace_destroyed & 2) { 631 p->p_flags &= ~P_INEXEC; 632 if (p->p_stops) 633 wakeup(&p->p_stype); 634 } 635 lwkt_reltoken(&p->p_token); 636 if (imgp->vmspace_destroyed) { 637 /* 638 * Sorry, no more process anymore. exit gracefully. 639 * However we can't die right here, because our 640 * caller might have to clean up, so indicate a 641 * lethal error by returning -1. 642 */ 643 return (-1); 644 } else { 645 return (error); 646 } 647 } 648 649 /* 650 * execve() system call. 651 */ 652 int 653 sys_execve(struct sysmsg *sysmsg, const struct execve_args *uap) 654 { 655 struct nlookupdata nd; 656 struct image_args args; 657 int error; 658 659 bzero(&args, sizeof(args)); 660 661 error = nlookup_init(&nd, uap->fname, UIO_USERSPACE, NLC_FOLLOW); 662 if (error == 0) { 663 error = exec_copyin_args(&args, uap->fname, PATH_USERSPACE, 664 uap->argv, uap->envv); 665 } 666 if (error == 0) 667 error = kern_execve(&nd, NULL, 0, &args); 668 nlookup_done(&nd); 669 exec_free_args(&args); 670 671 if (error < 0) { 672 /* We hit a lethal error condition. Let's die now. */ 673 exit1(W_EXITCODE(0, SIGABRT)); 674 /* NOTREACHED */ 675 } 676 677 /* 678 * The syscall result is returned in registers to the new program. 679 * Linux will register %edx as an atexit function and we must be 680 * sure to set it to 0. XXX 681 */ 682 if (error == 0) 683 sysmsg->sysmsg_result64 = 0; 684 685 return (error); 686 } 687 688 /* 689 * fexecve() system call. 690 */ 691 int 692 sys_fexecve(struct sysmsg *sysmsg, const struct fexecve_args *uap) 693 { 694 struct image_args args; 695 struct thread *td = curthread; 696 struct file *fp; 697 char fileflags; 698 char fname[32]; /* "/dev/fd/xxx" */ 699 int error; 700 701 if ((error = holdvnode2(td, uap->fd, &fp, &fileflags)) != 0) 702 return (error); 703 704 /* 705 * Require a descriptor opened only with O_RDONLY or O_EXEC. 706 * XXX: missing O_EXEC support 707 */ 708 if ((fp->f_flag & FWRITE) != 0 || (fp->f_flag & FREAD) == 0) { 709 error = EBADF; 710 goto done; 711 } 712 713 /* 714 * The 'fname' argument is required when executing an 715 * interpreted program because the interpreter must know 716 * the script path. Supply it with '/dev/fd/xxx'. 717 */ 718 ksnprintf(fname, sizeof(fname), "/dev/fd/%d", uap->fd); 719 bzero(&args, sizeof(args)); 720 error = exec_copyin_args(&args, fname, PATH_SYSSPACE, 721 uap->argv, uap->envv); 722 if (error == 0) 723 error = kern_execve(NULL, fp, fileflags, &args); 724 exec_free_args(&args); 725 726 if (error < 0) { 727 /* We hit a lethal error condition. Let's die now. */ 728 exit1(W_EXITCODE(0, SIGABRT)); 729 /* NOTREACHED */ 730 } 731 732 /* 733 * The syscall result is returned in registers to the new program. 734 * Linux will register %edx as an atexit function and we must be 735 * sure to set it to 0. XXX 736 */ 737 if (error == 0) 738 sysmsg->sysmsg_result64 = 0; 739 740 done: 741 fdrop(fp); 742 return (error); 743 } 744 745 int 746 exec_map_page(struct image_params *imgp, vm_pindex_t pageno, 747 struct lwbuf **plwb, const char **pdata) 748 { 749 int rv; 750 vm_page_t ma; 751 vm_page_t m; 752 vm_object_t object; 753 754 /* 755 * The file has to be mappable. 756 */ 757 if ((object = imgp->vp->v_object) == NULL) 758 return (EIO); 759 760 if (pageno >= object->size) 761 return (EIO); 762 763 /* 764 * Shortcut using shared locks, improve concurrent execs. 765 */ 766 vm_object_hold_shared(object); 767 m = vm_page_lookup(object, pageno); 768 if (m) { 769 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) { 770 vm_page_hold(m); 771 vm_page_sleep_busy(m, FALSE, "execpg"); 772 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL && 773 m->object == object && m->pindex == pageno) { 774 vm_object_drop(object); 775 goto done; 776 } 777 vm_page_unhold(m); 778 } 779 } 780 vm_object_drop(object); 781 782 /* 783 * Do it the hard way 784 */ 785 vm_object_hold(object); 786 m = vm_page_grab(object, pageno, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 787 while ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 788 ma = m; 789 790 /* 791 * get_pages unbusies all the requested pages except the 792 * primary page (at index 0 in this case). The primary 793 * page may have been wired during the pagein (e.g. by 794 * the buffer cache) so vnode_pager_freepage() must be 795 * used to properly release it. 796 */ 797 rv = vm_pager_get_page(object, pageno, &ma, 1); 798 m = vm_page_lookup(object, pageno); 799 800 if (rv != VM_PAGER_OK || m == NULL || m->valid == 0) { 801 if (m) { 802 vm_page_protect(m, VM_PROT_NONE); 803 vnode_pager_freepage(m); 804 } 805 vm_object_drop(object); 806 return EIO; 807 } 808 } 809 vm_page_hold(m); 810 vm_page_wakeup(m); /* unbusy the page */ 811 vm_object_drop(object); 812 813 done: 814 *plwb = lwbuf_alloc(m, *plwb); 815 *pdata = (void *)lwbuf_kva(*plwb); 816 817 return (0); 818 } 819 820 /* 821 * Map the first page of an executable image. 822 * 823 * NOTE: If the mapping fails we have to NULL-out firstpage which may 824 * still be pointing to our supplied lwp structure. 825 */ 826 int 827 exec_map_first_page(struct image_params *imgp) 828 { 829 int err; 830 831 if (imgp->firstpage) 832 exec_unmap_first_page(imgp); 833 834 imgp->firstpage = &imgp->firstpage_cache; 835 err = exec_map_page(imgp, 0, &imgp->firstpage, &imgp->image_header); 836 837 if (err) { 838 imgp->firstpage = NULL; 839 return err; 840 } 841 842 return 0; 843 } 844 845 void 846 exec_unmap_page(struct lwbuf *lwb) 847 { 848 vm_page_t m; 849 850 crit_enter(); 851 if (lwb != NULL) { 852 m = lwbuf_page(lwb); 853 lwbuf_free(lwb); 854 vm_page_unhold(m); 855 } 856 crit_exit(); 857 } 858 859 void 860 exec_unmap_first_page(struct image_params *imgp) 861 { 862 exec_unmap_page(imgp->firstpage); 863 imgp->firstpage = NULL; 864 imgp->image_header = NULL; 865 } 866 867 /* 868 * Destroy old address space, and allocate a new stack 869 * The new stack is only SGROWSIZ large because it is grown 870 * automatically in trap.c. 871 * 872 * This is the point of no return. 873 */ 874 int 875 exec_new_vmspace(struct image_params *imgp, struct vmspace *vmcopy) 876 { 877 struct vmspace *vmspace = imgp->proc->p_vmspace; 878 vm_offset_t stack_addr = USRSTACK - maxssiz; 879 struct lwp *lp; 880 struct proc *p; 881 vm_map_t map; 882 int error; 883 884 /* 885 * Indicate that we cannot gracefully error out any more, kill 886 * any other threads present, and set P_INEXEC to indicate that 887 * we are now messing with the process structure proper. 888 * 889 * If killalllwps() races return an error which coupled with 890 * vmspace_destroyed will cause us to exit. This is what we 891 * want since another thread is patiently waiting for us to exit 892 * in that case. 893 */ 894 lp = curthread->td_lwp; 895 p = lp->lwp_proc; 896 imgp->vmspace_destroyed = 1; 897 898 if (curthread->td_proc->p_nthreads > 1) { 899 error = killalllwps(1); 900 if (error) 901 return (error); 902 } 903 imgp->vmspace_destroyed |= 2; /* we are responsible for P_INEXEC */ 904 p->p_flags |= P_INEXEC; 905 906 /* 907 * Tell procfs to release its hold on the process. It 908 * will return EAGAIN. 909 */ 910 if (p->p_stops) 911 wakeup(&p->p_stype); 912 913 /* 914 * After setting P_INEXEC wait for any remaining references to 915 * the process (p) to go away. 916 * 917 * In particular, a vfork/exec sequence will replace p->p_vmspace 918 * and we must interlock anyone trying to access the space (aka 919 * procfs or sys_process.c calling procfs_domem()). 920 * 921 * If P_PPWAIT is set the parent vfork()'d and has a PHOLD() on us. 922 */ 923 PSTALL(p, "exec1", ((p->p_flags & P_PPWAIT) ? 1 : 0)); 924 925 /* 926 * Blow away entire process VM, if address space not shared, 927 * otherwise, create a new VM space so that other threads are 928 * not disrupted. If we are execing a resident vmspace we 929 * create a duplicate of it and remap the stack. 930 */ 931 map = &vmspace->vm_map; 932 if (vmcopy) { 933 vmspace_exec(imgp->proc, vmcopy); 934 vmspace = imgp->proc->p_vmspace; 935 pmap_remove_pages(vmspace_pmap(vmspace), stack_addr, USRSTACK); 936 map = &vmspace->vm_map; 937 } else if (vmspace_getrefs(vmspace) == 1) { 938 shmexit(vmspace); 939 pmap_remove_pages(vmspace_pmap(vmspace), 940 0, VM_MAX_USER_ADDRESS); 941 vm_map_remove(map, 0, VM_MAX_USER_ADDRESS); 942 } else { 943 vmspace_exec(imgp->proc, NULL); 944 vmspace = imgp->proc->p_vmspace; 945 map = &vmspace->vm_map; 946 } 947 948 /* 949 * Really make sure lwp-specific and process-specific mappings 950 * are gone. 951 * 952 * Once we've done that, and because we are the only LWP left, with 953 * no TID-dependent mappings, we can reset the TID to 1 (the RB tree 954 * will remain consistent since it has only one entry). This way 955 * the exec'd program gets a nice deterministic tid of 1. 956 */ 957 lwp_userunmap(lp); 958 proc_userunmap(p); 959 lp->lwp_tid = 1; 960 p->p_lasttid = 1; 961 962 /* 963 * Allocate a new stack, generally make the stack non-executable 964 * but allow the program to adjust that (the program may desire to 965 * use areas of the stack for executable code). 966 */ 967 error = vm_map_stack(&vmspace->vm_map, &stack_addr, (vm_size_t)maxssiz, 968 0, 969 VM_PROT_READ|VM_PROT_WRITE, 970 VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE, 971 0); 972 if (error) 973 return (error); 974 975 /* 976 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 977 * VM_STACK case, but they are still used to monitor the size of the 978 * process stack so we can check the stack rlimit. 979 */ 980 vmspace->vm_ssize = sgrowsiz; /* in bytes */ 981 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 982 983 return(0); 984 } 985 986 /* 987 * Copy out argument and environment strings from the old process 988 * address space into the temporary string buffer. 989 */ 990 static int 991 exec_copyin_args(struct image_args *args, char *fname, 992 enum exec_path_segflg segflg, char **argv, char **envv) 993 { 994 char *argp, *envp; 995 int error = 0; 996 size_t length; 997 998 args->buf = objcache_get(exec_objcache, M_WAITOK); 999 if (args->buf == NULL) 1000 return (ENOMEM); 1001 1002 args->begin_argv = args->buf; 1003 args->endp = args->begin_argv; 1004 args->space = ARG_MAX; 1005 1006 args->fname = args->buf + ARG_MAX; 1007 1008 /* 1009 * Copy the file name. 1010 */ 1011 if (segflg == PATH_SYSSPACE) 1012 error = copystr(fname, args->fname, PATH_MAX, &length); 1013 else 1014 error = copyinstr(fname, args->fname, PATH_MAX, &length); 1015 if (error) 1016 return (error); 1017 1018 /* 1019 * Extract argument strings. argv may not be NULL. The argv 1020 * array is terminated by a NULL entry. We special-case the 1021 * situation where argv[0] is NULL by passing { filename, NULL } 1022 * to the new program to guarentee that the interpreter knows what 1023 * file to open in case we exec an interpreted file. Note that 1024 * a NULL argv[0] terminates the argv[] array. 1025 * 1026 * XXX the special-casing of argv[0] is historical and needs to be 1027 * revisited. 1028 */ 1029 if (argv == NULL) 1030 error = EFAULT; 1031 if (error == 0) { 1032 while ((argp = (caddr_t)(intptr_t) 1033 fuword64((uintptr_t *)argv++)) != NULL) { 1034 if (argp == (caddr_t)-1) { 1035 error = EFAULT; 1036 break; 1037 } 1038 error = copyinstr(argp, args->endp, 1039 args->space, &length); 1040 if (error) { 1041 if (error == ENAMETOOLONG) 1042 error = E2BIG; 1043 break; 1044 } 1045 args->space -= length; 1046 args->endp += length; 1047 args->argc++; 1048 } 1049 if (args->argc == 0 && error == 0) { 1050 length = strlen(args->fname) + 1; 1051 if (length > args->space) { 1052 error = E2BIG; 1053 } else { 1054 bcopy(args->fname, args->endp, length); 1055 args->space -= length; 1056 args->endp += length; 1057 args->argc++; 1058 } 1059 } 1060 } 1061 1062 args->begin_envv = args->endp; 1063 1064 /* 1065 * extract environment strings. envv may be NULL. 1066 */ 1067 if (envv && error == 0) { 1068 while ((envp = (caddr_t)(intptr_t) 1069 fuword64((uintptr_t *)envv++))) { 1070 if (envp == (caddr_t) -1) { 1071 error = EFAULT; 1072 break; 1073 } 1074 error = copyinstr(envp, args->endp, 1075 args->space, &length); 1076 if (error) { 1077 if (error == ENAMETOOLONG) 1078 error = E2BIG; 1079 break; 1080 } 1081 args->space -= length; 1082 args->endp += length; 1083 args->envc++; 1084 } 1085 } 1086 1087 return (error); 1088 } 1089 1090 static void 1091 exec_free_args(struct image_args *args) 1092 { 1093 if (args->buf) { 1094 objcache_put(exec_objcache, args->buf); 1095 args->buf = NULL; 1096 } 1097 } 1098 1099 /* 1100 * Copy strings out to the new process address space, constructing 1101 * new arg and env vector tables. Return a pointer to the base 1102 * so that it can be used as the initial stack pointer. 1103 * 1104 * The format is, roughly: 1105 * 1106 * [argv[]] <-- vectp 1107 * [envp[]] 1108 * [ELF_Auxargs] 1109 * 1110 * [args & env] <-- destp 1111 * [sgap] 1112 * [SPARE_USRSPACE] 1113 * [execpath] 1114 * [szsigcode] RO|NX 1115 * [ps_strings] RO|NX Top of user stack 1116 * 1117 */ 1118 static register_t * 1119 exec_copyout_strings(struct image_params *imgp) 1120 { 1121 int argc, envc, sgap; 1122 int gap; 1123 int argsenvspace; 1124 char **vectp; 1125 char *stringp, *destp, *szsigbase; 1126 register_t *stack_base; 1127 struct ps_strings *arginfo; 1128 size_t execpath_len; 1129 int szsigcode; 1130 1131 /* 1132 * Calculate string base and vector table pointers. 1133 * Also deal with signal trampoline code for this exec type. 1134 */ 1135 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1136 execpath_len = strlen(imgp->execpath) + 1; 1137 else 1138 execpath_len = 0; 1139 arginfo = (struct ps_strings *)PS_STRINGS; 1140 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 1141 1142 argsenvspace = roundup((ARG_MAX - imgp->args->space), sizeof(char *)); 1143 gap = stackgap_random; 1144 cpu_ccfence(); 1145 if (gap != 0) { 1146 if (gap < 0) 1147 sgap = ALIGN(-gap); 1148 else 1149 sgap = ALIGN(karc4random() & (gap - 1)); 1150 } else { 1151 sgap = 0; 1152 } 1153 1154 /* 1155 * Calculate destp, which points to [args & env] and above. 1156 */ 1157 szsigbase = (char *)(intptr_t) 1158 trunc_page64((intptr_t)arginfo - szsigcode); 1159 szsigbase -= SZSIGCODE_EXTRA_BYTES; 1160 destp = szsigbase - 1161 roundup(execpath_len, sizeof(char *)) - 1162 SPARE_USRSPACE - 1163 sgap - 1164 argsenvspace; 1165 1166 /* 1167 * install sigcode 1168 */ 1169 if (szsigcode) 1170 copyout(imgp->proc->p_sysent->sv_sigcode, szsigbase, szsigcode); 1171 1172 /* 1173 * Copy the image path for the rtld 1174 */ 1175 if (execpath_len) { 1176 imgp->execpathp = (uintptr_t)szsigbase - 1177 roundup(execpath_len, sizeof(char *)); 1178 copyout(imgp->execpath, (void *)imgp->execpathp, execpath_len); 1179 } 1180 1181 /* 1182 * Calculate base for argv[], envp[], and ELF_Auxargs. 1183 */ 1184 vectp = (char **)destp - (AT_COUNT * 2); 1185 vectp -= imgp->args->argc + imgp->args->envc + 2; 1186 1187 stack_base = (register_t *)vectp; 1188 1189 stringp = imgp->args->begin_argv; 1190 argc = imgp->args->argc; 1191 envc = imgp->args->envc; 1192 1193 /* 1194 * Copy out strings - arguments and environment (at destp) 1195 */ 1196 copyout(stringp, destp, ARG_MAX - imgp->args->space); 1197 1198 /* 1199 * Fill in "ps_strings" struct for ps, w, etc. 1200 */ 1201 suword64((void *)&arginfo->ps_argvstr, (uint64_t)(intptr_t)vectp); 1202 suword32((void *)&arginfo->ps_nargvstr, argc); 1203 1204 /* 1205 * Fill in argument portion of vector table. 1206 */ 1207 for (; argc > 0; --argc) { 1208 suword64((void *)vectp++, (uintptr_t)destp); 1209 while (*stringp++ != 0) 1210 destp++; 1211 destp++; 1212 } 1213 1214 /* a null vector table pointer separates the argp's from the envp's */ 1215 suword64((void *)vectp++, 0); 1216 1217 suword64((void *)&arginfo->ps_envstr, (uintptr_t)vectp); 1218 suword32((void *)&arginfo->ps_nenvstr, envc); 1219 1220 /* 1221 * Fill in environment portion of vector table. 1222 */ 1223 for (; envc > 0; --envc) { 1224 suword64((void *)vectp++, (uintptr_t)destp); 1225 while (*stringp++ != 0) 1226 destp++; 1227 destp++; 1228 } 1229 1230 /* end of vector table is a null pointer */ 1231 suword64((void *)vectp, 0); 1232 1233 /* 1234 * Make the signal trampoline executable and read-only. 1235 */ 1236 vm_map_protect(&imgp->proc->p_vmspace->vm_map, 1237 (vm_offset_t)szsigbase, 1238 (vm_offset_t)szsigbase + PAGE_SIZE, 1239 VM_PROT_READ|VM_PROT_EXECUTE, FALSE); 1240 1241 return (stack_base); 1242 } 1243 1244 /* 1245 * Check permissions of file to execute. 1246 * Return 0 for success or error code on failure. 1247 */ 1248 int 1249 exec_check_permissions(struct image_params *imgp, struct mount *topmnt) 1250 { 1251 struct proc *p = imgp->proc; 1252 struct vnode *vp = imgp->vp; 1253 struct vattr_lite *lvap = imgp->lvap; 1254 int error; 1255 1256 /* Get file attributes */ 1257 error = VOP_GETATTR_LITE(vp, lvap); 1258 if (error) 1259 return (error); 1260 1261 /* 1262 * 1) Check if file execution is disabled for the filesystem that this 1263 * file resides on. 1264 * 2) Insure that at least one execute bit is on - otherwise root 1265 * will always succeed, and we don't want to happen unless the 1266 * file really is executable. 1267 * 3) Insure that the file is a regular file. 1268 */ 1269 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1270 ((topmnt != NULL) && (topmnt->mnt_flag & MNT_NOEXEC)) || 1271 ((lvap->va_mode & 0111) == 0) || 1272 (lvap->va_type != VREG)) { 1273 return (EACCES); 1274 } 1275 1276 /* 1277 * Zero length files can't be exec'd 1278 */ 1279 if (lvap->va_size == 0) 1280 return (ENOEXEC); 1281 1282 /* 1283 * Check for execute permission to file based on current credentials. 1284 */ 1285 error = VOP_EACCESS(vp, VEXEC, p->p_ucred); 1286 if (error) 1287 return (error); 1288 1289 /* 1290 * Check number of open-for-writes on the file and deny execution 1291 * if there are any. 1292 */ 1293 if (vp->v_writecount) 1294 return (ETXTBSY); 1295 1296 /* 1297 * Call filesystem specific open routine, which allows us to read, 1298 * write, and mmap the file. Without the VOP_OPEN we can only 1299 * stat the file. 1300 */ 1301 error = VOP_OPEN(vp, FREAD, p->p_ucred, NULL); 1302 if (error) 1303 return (error); 1304 1305 return (0); 1306 } 1307 1308 /* 1309 * Exec handler registration 1310 */ 1311 int 1312 exec_register(const struct execsw *execsw_arg) 1313 { 1314 const struct execsw **es, **xs, **newexecsw; 1315 int count = 2; /* New slot and trailing NULL */ 1316 1317 if (execsw) 1318 for (es = execsw; *es; es++) 1319 count++; 1320 newexecsw = kmalloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1321 xs = newexecsw; 1322 if (execsw) 1323 for (es = execsw; *es; es++) 1324 *xs++ = *es; 1325 *xs++ = execsw_arg; 1326 *xs = NULL; 1327 if (execsw) 1328 kfree(execsw, M_TEMP); 1329 execsw = newexecsw; 1330 return 0; 1331 } 1332 1333 int 1334 exec_unregister(const struct execsw *execsw_arg) 1335 { 1336 const struct execsw **es, **xs, **newexecsw; 1337 int count = 1; 1338 1339 if (execsw == NULL) 1340 panic("unregister with no handlers left?"); 1341 1342 for (es = execsw; *es; es++) { 1343 if (*es == execsw_arg) 1344 break; 1345 } 1346 if (*es == NULL) 1347 return ENOENT; 1348 for (es = execsw; *es; es++) 1349 if (*es != execsw_arg) 1350 count++; 1351 newexecsw = kmalloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1352 xs = newexecsw; 1353 for (es = execsw; *es; es++) 1354 if (*es != execsw_arg) 1355 *xs++ = *es; 1356 *xs = NULL; 1357 if (execsw) 1358 kfree(execsw, M_TEMP); 1359 execsw = newexecsw; 1360 return 0; 1361 } 1362