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 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 #include "opt_capsicum.h" 31 #include "opt_hwpmc_hooks.h" 32 #include "opt_kdtrace.h" 33 #include "opt_ktrace.h" 34 #include "opt_vm.h" 35 36 #include <sys/param.h> 37 #include <sys/capability.h> 38 #include <sys/systm.h> 39 #include <sys/capability.h> 40 #include <sys/eventhandler.h> 41 #include <sys/lock.h> 42 #include <sys/mutex.h> 43 #include <sys/sysproto.h> 44 #include <sys/signalvar.h> 45 #include <sys/kernel.h> 46 #include <sys/mount.h> 47 #include <sys/filedesc.h> 48 #include <sys/fcntl.h> 49 #include <sys/acct.h> 50 #include <sys/exec.h> 51 #include <sys/imgact.h> 52 #include <sys/imgact_elf.h> 53 #include <sys/wait.h> 54 #include <sys/malloc.h> 55 #include <sys/priv.h> 56 #include <sys/proc.h> 57 #include <sys/pioctl.h> 58 #include <sys/namei.h> 59 #include <sys/resourcevar.h> 60 #include <sys/rwlock.h> 61 #include <sys/sched.h> 62 #include <sys/sdt.h> 63 #include <sys/sf_buf.h> 64 #include <sys/syscallsubr.h> 65 #include <sys/sysent.h> 66 #include <sys/shm.h> 67 #include <sys/sysctl.h> 68 #include <sys/vnode.h> 69 #include <sys/stat.h> 70 #ifdef KTRACE 71 #include <sys/ktrace.h> 72 #endif 73 74 #include <vm/vm.h> 75 #include <vm/vm_param.h> 76 #include <vm/pmap.h> 77 #include <vm/vm_page.h> 78 #include <vm/vm_map.h> 79 #include <vm/vm_kern.h> 80 #include <vm/vm_extern.h> 81 #include <vm/vm_object.h> 82 #include <vm/vm_pager.h> 83 84 #ifdef HWPMC_HOOKS 85 #include <sys/pmckern.h> 86 #endif 87 88 #include <machine/reg.h> 89 90 #include <security/audit/audit.h> 91 #include <security/mac/mac_framework.h> 92 93 #ifdef KDTRACE_HOOKS 94 #include <sys/dtrace_bsd.h> 95 dtrace_execexit_func_t dtrace_fasttrap_exec; 96 #endif 97 98 SDT_PROVIDER_DECLARE(proc); 99 SDT_PROBE_DEFINE1(proc, kernel, , exec, exec, "char *"); 100 SDT_PROBE_DEFINE1(proc, kernel, , exec_failure, exec-failure, "int"); 101 SDT_PROBE_DEFINE1(proc, kernel, , exec_success, exec-success, "char *"); 102 103 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 104 105 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 106 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 107 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 108 static int do_execve(struct thread *td, struct image_args *args, 109 struct mac *mac_p); 110 111 /* XXX This should be vm_size_t. */ 112 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD, 113 NULL, 0, sysctl_kern_ps_strings, "LU", ""); 114 115 /* XXX This should be vm_size_t. */ 116 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 117 CTLFLAG_CAPRD, NULL, 0, sysctl_kern_usrstack, "LU", ""); 118 119 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 120 NULL, 0, sysctl_kern_stackprot, "I", ""); 121 122 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 123 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 124 &ps_arg_cache_limit, 0, ""); 125 126 static int map_at_zero = 0; 127 TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero); 128 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &map_at_zero, 0, 129 "Permit processes to map an object at virtual address 0."); 130 131 static int 132 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 133 { 134 struct proc *p; 135 int error; 136 137 p = curproc; 138 #ifdef SCTL_MASK32 139 if (req->flags & SCTL_MASK32) { 140 unsigned int val; 141 val = (unsigned int)p->p_sysent->sv_psstrings; 142 error = SYSCTL_OUT(req, &val, sizeof(val)); 143 } else 144 #endif 145 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 146 sizeof(p->p_sysent->sv_psstrings)); 147 return error; 148 } 149 150 static int 151 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 152 { 153 struct proc *p; 154 int error; 155 156 p = curproc; 157 #ifdef SCTL_MASK32 158 if (req->flags & SCTL_MASK32) { 159 unsigned int val; 160 val = (unsigned int)p->p_sysent->sv_usrstack; 161 error = SYSCTL_OUT(req, &val, sizeof(val)); 162 } else 163 #endif 164 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 165 sizeof(p->p_sysent->sv_usrstack)); 166 return error; 167 } 168 169 static int 170 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 171 { 172 struct proc *p; 173 174 p = curproc; 175 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 176 sizeof(p->p_sysent->sv_stackprot))); 177 } 178 179 /* 180 * Each of the items is a pointer to a `const struct execsw', hence the 181 * double pointer here. 182 */ 183 static const struct execsw **execsw; 184 185 #ifndef _SYS_SYSPROTO_H_ 186 struct execve_args { 187 char *fname; 188 char **argv; 189 char **envv; 190 }; 191 #endif 192 193 int 194 sys_execve(td, uap) 195 struct thread *td; 196 struct execve_args /* { 197 char *fname; 198 char **argv; 199 char **envv; 200 } */ *uap; 201 { 202 int error; 203 struct image_args args; 204 205 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 206 uap->argv, uap->envv); 207 if (error == 0) 208 error = kern_execve(td, &args, NULL); 209 return (error); 210 } 211 212 #ifndef _SYS_SYSPROTO_H_ 213 struct fexecve_args { 214 int fd; 215 char **argv; 216 char **envv; 217 } 218 #endif 219 int 220 sys_fexecve(struct thread *td, struct fexecve_args *uap) 221 { 222 int error; 223 struct image_args args; 224 225 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 226 uap->argv, uap->envv); 227 if (error == 0) { 228 args.fd = uap->fd; 229 error = kern_execve(td, &args, NULL); 230 } 231 return (error); 232 } 233 234 #ifndef _SYS_SYSPROTO_H_ 235 struct __mac_execve_args { 236 char *fname; 237 char **argv; 238 char **envv; 239 struct mac *mac_p; 240 }; 241 #endif 242 243 int 244 sys___mac_execve(td, uap) 245 struct thread *td; 246 struct __mac_execve_args /* { 247 char *fname; 248 char **argv; 249 char **envv; 250 struct mac *mac_p; 251 } */ *uap; 252 { 253 #ifdef MAC 254 int error; 255 struct image_args args; 256 257 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 258 uap->argv, uap->envv); 259 if (error == 0) 260 error = kern_execve(td, &args, uap->mac_p); 261 return (error); 262 #else 263 return (ENOSYS); 264 #endif 265 } 266 267 /* 268 * XXX: kern_execve has the astonishing property of not always returning to 269 * the caller. If sufficiently bad things happen during the call to 270 * do_execve(), it can end up calling exit1(); as a result, callers must 271 * avoid doing anything which they might need to undo (e.g., allocating 272 * memory). 273 */ 274 int 275 kern_execve(td, args, mac_p) 276 struct thread *td; 277 struct image_args *args; 278 struct mac *mac_p; 279 { 280 struct proc *p = td->td_proc; 281 int error; 282 283 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 284 args->begin_envv - args->begin_argv); 285 AUDIT_ARG_ENVV(args->begin_envv, args->envc, 286 args->endp - args->begin_envv); 287 if (p->p_flag & P_HADTHREADS) { 288 PROC_LOCK(p); 289 if (thread_single(SINGLE_BOUNDARY)) { 290 PROC_UNLOCK(p); 291 exec_free_args(args); 292 return (ERESTART); /* Try again later. */ 293 } 294 PROC_UNLOCK(p); 295 } 296 297 error = do_execve(td, args, mac_p); 298 299 if (p->p_flag & P_HADTHREADS) { 300 PROC_LOCK(p); 301 /* 302 * If success, we upgrade to SINGLE_EXIT state to 303 * force other threads to suicide. 304 */ 305 if (error == 0) 306 thread_single(SINGLE_EXIT); 307 else 308 thread_single_end(); 309 PROC_UNLOCK(p); 310 } 311 312 return (error); 313 } 314 315 /* 316 * In-kernel implementation of execve(). All arguments are assumed to be 317 * userspace pointers from the passed thread. 318 */ 319 static int 320 do_execve(td, args, mac_p) 321 struct thread *td; 322 struct image_args *args; 323 struct mac *mac_p; 324 { 325 struct proc *p = td->td_proc; 326 struct nameidata nd; 327 struct ucred *newcred = NULL, *oldcred; 328 struct uidinfo *euip; 329 register_t *stack_base; 330 int error, i; 331 struct image_params image_params, *imgp; 332 struct vattr attr; 333 int (*img_first)(struct image_params *); 334 struct pargs *oldargs = NULL, *newargs = NULL; 335 struct sigacts *oldsigacts, *newsigacts; 336 #ifdef KTRACE 337 struct vnode *tracevp = NULL; 338 struct ucred *tracecred = NULL; 339 #endif 340 struct vnode *textvp = NULL, *binvp = NULL; 341 cap_rights_t rights; 342 int credential_changing; 343 int textset; 344 #ifdef MAC 345 struct label *interpvplabel = NULL; 346 int will_transition; 347 #endif 348 #ifdef HWPMC_HOOKS 349 struct pmckern_procexec pe; 350 #endif 351 static const char fexecv_proc_title[] = "(fexecv)"; 352 353 imgp = &image_params; 354 355 /* 356 * Lock the process and set the P_INEXEC flag to indicate that 357 * it should be left alone until we're done here. This is 358 * necessary to avoid race conditions - e.g. in ptrace() - 359 * that might allow a local user to illicitly obtain elevated 360 * privileges. 361 */ 362 PROC_LOCK(p); 363 KASSERT((p->p_flag & P_INEXEC) == 0, 364 ("%s(): process already has P_INEXEC flag", __func__)); 365 p->p_flag |= P_INEXEC; 366 PROC_UNLOCK(p); 367 368 /* 369 * Initialize part of the common data 370 */ 371 imgp->proc = p; 372 imgp->execlabel = NULL; 373 imgp->attr = &attr; 374 imgp->entry_addr = 0; 375 imgp->reloc_base = 0; 376 imgp->vmspace_destroyed = 0; 377 imgp->interpreted = 0; 378 imgp->opened = 0; 379 imgp->interpreter_name = NULL; 380 imgp->auxargs = NULL; 381 imgp->vp = NULL; 382 imgp->object = NULL; 383 imgp->firstpage = NULL; 384 imgp->ps_strings = 0; 385 imgp->auxarg_size = 0; 386 imgp->args = args; 387 imgp->execpath = imgp->freepath = NULL; 388 imgp->execpathp = 0; 389 imgp->canary = 0; 390 imgp->canarylen = 0; 391 imgp->pagesizes = 0; 392 imgp->pagesizeslen = 0; 393 imgp->stack_prot = 0; 394 395 #ifdef MAC 396 error = mac_execve_enter(imgp, mac_p); 397 if (error) 398 goto exec_fail; 399 #endif 400 401 imgp->image_header = NULL; 402 403 /* 404 * Translate the file name. namei() returns a vnode pointer 405 * in ni_vp amoung other things. 406 * 407 * XXXAUDIT: It would be desirable to also audit the name of the 408 * interpreter if this is an interpreted binary. 409 */ 410 if (args->fname != NULL) { 411 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 412 | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 413 } 414 415 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 416 417 interpret: 418 if (args->fname != NULL) { 419 #ifdef CAPABILITY_MODE 420 /* 421 * While capability mode can't reach this point via direct 422 * path arguments to execve(), we also don't allow 423 * interpreters to be used in capability mode (for now). 424 * Catch indirect lookups and return a permissions error. 425 */ 426 if (IN_CAPABILITY_MODE(td)) { 427 error = ECAPMODE; 428 goto exec_fail; 429 } 430 #endif 431 error = namei(&nd); 432 if (error) 433 goto exec_fail; 434 435 binvp = nd.ni_vp; 436 imgp->vp = binvp; 437 } else { 438 AUDIT_ARG_FD(args->fd); 439 /* 440 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 441 */ 442 error = fgetvp_exec(td, args->fd, 443 cap_rights_init(&rights, CAP_FEXECVE), &binvp); 444 if (error) 445 goto exec_fail; 446 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY); 447 AUDIT_ARG_VNODE1(binvp); 448 imgp->vp = binvp; 449 } 450 451 /* 452 * Check file permissions (also 'opens' file) 453 */ 454 error = exec_check_permissions(imgp); 455 if (error) 456 goto exec_fail_dealloc; 457 458 imgp->object = imgp->vp->v_object; 459 if (imgp->object != NULL) 460 vm_object_reference(imgp->object); 461 462 /* 463 * Set VV_TEXT now so no one can write to the executable while we're 464 * activating it. 465 * 466 * Remember if this was set before and unset it in case this is not 467 * actually an executable image. 468 */ 469 textset = VOP_IS_TEXT(imgp->vp); 470 VOP_SET_TEXT(imgp->vp); 471 472 error = exec_map_first_page(imgp); 473 if (error) 474 goto exec_fail_dealloc; 475 476 imgp->proc->p_osrel = 0; 477 /* 478 * If the current process has a special image activator it 479 * wants to try first, call it. For example, emulating shell 480 * scripts differently. 481 */ 482 error = -1; 483 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 484 error = img_first(imgp); 485 486 /* 487 * Loop through the list of image activators, calling each one. 488 * An activator returns -1 if there is no match, 0 on success, 489 * and an error otherwise. 490 */ 491 for (i = 0; error == -1 && execsw[i]; ++i) { 492 if (execsw[i]->ex_imgact == NULL || 493 execsw[i]->ex_imgact == img_first) { 494 continue; 495 } 496 error = (*execsw[i]->ex_imgact)(imgp); 497 } 498 499 if (error) { 500 if (error == -1) { 501 if (textset == 0) 502 VOP_UNSET_TEXT(imgp->vp); 503 error = ENOEXEC; 504 } 505 goto exec_fail_dealloc; 506 } 507 508 /* 509 * Special interpreter operation, cleanup and loop up to try to 510 * activate the interpreter. 511 */ 512 if (imgp->interpreted) { 513 exec_unmap_first_page(imgp); 514 /* 515 * VV_TEXT needs to be unset for scripts. There is a short 516 * period before we determine that something is a script where 517 * VV_TEXT will be set. The vnode lock is held over this 518 * entire period so nothing should illegitimately be blocked. 519 */ 520 VOP_UNSET_TEXT(imgp->vp); 521 /* free name buffer and old vnode */ 522 if (args->fname != NULL) 523 NDFREE(&nd, NDF_ONLY_PNBUF); 524 #ifdef MAC 525 mac_execve_interpreter_enter(binvp, &interpvplabel); 526 #endif 527 if (imgp->opened) { 528 VOP_CLOSE(binvp, FREAD, td->td_ucred, td); 529 imgp->opened = 0; 530 } 531 vput(binvp); 532 vm_object_deallocate(imgp->object); 533 imgp->object = NULL; 534 /* set new name to that of the interpreter */ 535 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 536 UIO_SYSSPACE, imgp->interpreter_name, td); 537 args->fname = imgp->interpreter_name; 538 goto interpret; 539 } 540 541 /* 542 * NB: We unlock the vnode here because it is believed that none 543 * of the sv_copyout_strings/sv_fixup operations require the vnode. 544 */ 545 VOP_UNLOCK(imgp->vp, 0); 546 547 /* 548 * Do the best to calculate the full path to the image file. 549 */ 550 if (imgp->auxargs != NULL && 551 ((args->fname != NULL && args->fname[0] == '/') || 552 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0)) 553 imgp->execpath = args->fname; 554 555 /* 556 * Copy out strings (args and env) and initialize stack base 557 */ 558 if (p->p_sysent->sv_copyout_strings) 559 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 560 else 561 stack_base = exec_copyout_strings(imgp); 562 563 /* 564 * If custom stack fixup routine present for this process 565 * let it do the stack setup. 566 * Else stuff argument count as first item on stack 567 */ 568 if (p->p_sysent->sv_fixup != NULL) 569 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 570 else 571 suword(--stack_base, imgp->args->argc); 572 573 /* 574 * For security and other reasons, the file descriptor table cannot 575 * be shared after an exec. 576 */ 577 fdunshare(p, td); 578 579 /* 580 * Malloc things before we need locks. 581 */ 582 newcred = crget(); 583 euip = uifind(attr.va_uid); 584 i = imgp->args->begin_envv - imgp->args->begin_argv; 585 /* Cache arguments if they fit inside our allowance */ 586 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 587 newargs = pargs_alloc(i); 588 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 589 } 590 591 /* close files on exec */ 592 fdcloseexec(td); 593 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 594 595 /* Get a reference to the vnode prior to locking the proc */ 596 VREF(binvp); 597 598 /* 599 * For security and other reasons, signal handlers cannot 600 * be shared after an exec. The new process gets a copy of the old 601 * handlers. In execsigs(), the new process will have its signals 602 * reset. 603 */ 604 PROC_LOCK(p); 605 oldcred = crcopysafe(p, newcred); 606 if (sigacts_shared(p->p_sigacts)) { 607 oldsigacts = p->p_sigacts; 608 PROC_UNLOCK(p); 609 newsigacts = sigacts_alloc(); 610 sigacts_copy(newsigacts, oldsigacts); 611 PROC_LOCK(p); 612 p->p_sigacts = newsigacts; 613 } else 614 oldsigacts = NULL; 615 616 /* Stop profiling */ 617 stopprofclock(p); 618 619 /* reset caught signals */ 620 execsigs(p); 621 622 /* name this process - nameiexec(p, ndp) */ 623 bzero(p->p_comm, sizeof(p->p_comm)); 624 if (args->fname) 625 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 626 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 627 else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0) 628 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 629 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 630 #ifdef KTR 631 sched_clear_tdname(td); 632 #endif 633 634 /* 635 * mark as execed, wakeup the process that vforked (if any) and tell 636 * it that it now has its own resources back 637 */ 638 p->p_flag |= P_EXEC; 639 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 640 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 641 cv_broadcast(&p->p_pwait); 642 } 643 644 /* 645 * Implement image setuid/setgid. 646 * 647 * Don't honor setuid/setgid if the filesystem prohibits it or if 648 * the process is being traced. 649 * 650 * We disable setuid/setgid/etc in compatibility mode on the basis 651 * that most setugid applications are not written with that 652 * environment in mind, and will therefore almost certainly operate 653 * incorrectly. In principle there's no reason that setugid 654 * applications might not be useful in capability mode, so we may want 655 * to reconsider this conservative design choice in the future. 656 * 657 * XXXMAC: For the time being, use NOSUID to also prohibit 658 * transitions on the file system. 659 */ 660 credential_changing = 0; 661 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 662 attr.va_uid; 663 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 664 attr.va_gid; 665 #ifdef MAC 666 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 667 interpvplabel, imgp); 668 credential_changing |= will_transition; 669 #endif 670 671 if (credential_changing && 672 #ifdef CAPABILITY_MODE 673 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 674 #endif 675 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 676 (p->p_flag & P_TRACED) == 0) { 677 /* 678 * Turn off syscall tracing for set-id programs, except for 679 * root. Record any set-id flags first to make sure that 680 * we do not regain any tracing during a possible block. 681 */ 682 setsugid(p); 683 684 #ifdef KTRACE 685 if (p->p_tracecred != NULL && 686 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0)) 687 ktrprocexec(p, &tracecred, &tracevp); 688 #endif 689 /* 690 * Close any file descriptors 0..2 that reference procfs, 691 * then make sure file descriptors 0..2 are in use. 692 * 693 * setugidsafety() may call closef() and then pfind() 694 * which may grab the process lock. 695 * fdcheckstd() may call falloc() which may block to 696 * allocate memory, so temporarily drop the process lock. 697 */ 698 PROC_UNLOCK(p); 699 VOP_UNLOCK(imgp->vp, 0); 700 setugidsafety(td); 701 error = fdcheckstd(td); 702 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 703 if (error != 0) 704 goto done1; 705 PROC_LOCK(p); 706 /* 707 * Set the new credentials. 708 */ 709 if (attr.va_mode & S_ISUID) 710 change_euid(newcred, euip); 711 if (attr.va_mode & S_ISGID) 712 change_egid(newcred, attr.va_gid); 713 #ifdef MAC 714 if (will_transition) { 715 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 716 interpvplabel, imgp); 717 } 718 #endif 719 /* 720 * Implement correct POSIX saved-id behavior. 721 * 722 * XXXMAC: Note that the current logic will save the 723 * uid and gid if a MAC domain transition occurs, even 724 * though maybe it shouldn't. 725 */ 726 change_svuid(newcred, newcred->cr_uid); 727 change_svgid(newcred, newcred->cr_gid); 728 p->p_ucred = newcred; 729 newcred = NULL; 730 } else { 731 if (oldcred->cr_uid == oldcred->cr_ruid && 732 oldcred->cr_gid == oldcred->cr_rgid) 733 p->p_flag &= ~P_SUGID; 734 /* 735 * Implement correct POSIX saved-id behavior. 736 * 737 * XXX: It's not clear that the existing behavior is 738 * POSIX-compliant. A number of sources indicate that the 739 * saved uid/gid should only be updated if the new ruid is 740 * not equal to the old ruid, or the new euid is not equal 741 * to the old euid and the new euid is not equal to the old 742 * ruid. The FreeBSD code always updates the saved uid/gid. 743 * Also, this code uses the new (replaced) euid and egid as 744 * the source, which may or may not be the right ones to use. 745 */ 746 if (oldcred->cr_svuid != oldcred->cr_uid || 747 oldcred->cr_svgid != oldcred->cr_gid) { 748 change_svuid(newcred, newcred->cr_uid); 749 change_svgid(newcred, newcred->cr_gid); 750 p->p_ucred = newcred; 751 newcred = NULL; 752 } 753 } 754 755 /* 756 * Store the vp for use in procfs. This vnode was referenced prior 757 * to locking the proc lock. 758 */ 759 textvp = p->p_textvp; 760 p->p_textvp = binvp; 761 762 #ifdef KDTRACE_HOOKS 763 /* 764 * Tell the DTrace fasttrap provider about the exec if it 765 * has declared an interest. 766 */ 767 if (dtrace_fasttrap_exec) 768 dtrace_fasttrap_exec(p); 769 #endif 770 771 /* 772 * Notify others that we exec'd, and clear the P_INEXEC flag 773 * as we're now a bona fide freshly-execed process. 774 */ 775 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 776 p->p_flag &= ~P_INEXEC; 777 778 /* clear "fork but no exec" flag, as we _are_ execing */ 779 p->p_acflag &= ~AFORK; 780 781 /* 782 * Free any previous argument cache and replace it with 783 * the new argument cache, if any. 784 */ 785 oldargs = p->p_args; 786 p->p_args = newargs; 787 newargs = NULL; 788 789 #ifdef HWPMC_HOOKS 790 /* 791 * Check if system-wide sampling is in effect or if the 792 * current process is using PMCs. If so, do exec() time 793 * processing. This processing needs to happen AFTER the 794 * P_INEXEC flag is cleared. 795 * 796 * The proc lock needs to be released before taking the PMC 797 * SX. 798 */ 799 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 800 PROC_UNLOCK(p); 801 VOP_UNLOCK(imgp->vp, 0); 802 pe.pm_credentialschanged = credential_changing; 803 pe.pm_entryaddr = imgp->entry_addr; 804 805 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 806 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 807 } else 808 PROC_UNLOCK(p); 809 #else /* !HWPMC_HOOKS */ 810 PROC_UNLOCK(p); 811 #endif 812 813 /* Set values passed into the program in registers. */ 814 if (p->p_sysent->sv_setregs) 815 (*p->p_sysent->sv_setregs)(td, imgp, 816 (u_long)(uintptr_t)stack_base); 817 else 818 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 819 820 vfs_mark_atime(imgp->vp, td->td_ucred); 821 822 SDT_PROBE(proc, kernel, , exec_success, args->fname, 0, 0, 0, 0); 823 824 done1: 825 /* 826 * Free any resources malloc'd earlier that we didn't use. 827 */ 828 uifree(euip); 829 if (newcred == NULL) 830 crfree(oldcred); 831 else 832 crfree(newcred); 833 VOP_UNLOCK(imgp->vp, 0); 834 835 /* 836 * Handle deferred decrement of ref counts. 837 */ 838 if (textvp != NULL) 839 vrele(textvp); 840 if (binvp && error != 0) 841 vrele(binvp); 842 #ifdef KTRACE 843 if (tracevp != NULL) 844 vrele(tracevp); 845 if (tracecred != NULL) 846 crfree(tracecred); 847 #endif 848 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 849 pargs_drop(oldargs); 850 pargs_drop(newargs); 851 if (oldsigacts != NULL) 852 sigacts_free(oldsigacts); 853 854 exec_fail_dealloc: 855 856 /* 857 * free various allocated resources 858 */ 859 if (imgp->firstpage != NULL) 860 exec_unmap_first_page(imgp); 861 862 if (imgp->vp != NULL) { 863 if (args->fname) 864 NDFREE(&nd, NDF_ONLY_PNBUF); 865 if (imgp->opened) 866 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 867 vput(imgp->vp); 868 } 869 870 if (imgp->object != NULL) 871 vm_object_deallocate(imgp->object); 872 873 free(imgp->freepath, M_TEMP); 874 875 if (error == 0) { 876 PROC_LOCK(p); 877 td->td_dbgflags |= TDB_EXEC; 878 PROC_UNLOCK(p); 879 880 /* 881 * Stop the process here if its stop event mask has 882 * the S_EXEC bit set. 883 */ 884 STOPEVENT(p, S_EXEC, 0); 885 goto done2; 886 } 887 888 exec_fail: 889 /* we're done here, clear P_INEXEC */ 890 PROC_LOCK(p); 891 p->p_flag &= ~P_INEXEC; 892 PROC_UNLOCK(p); 893 894 SDT_PROBE(proc, kernel, , exec_failure, error, 0, 0, 0, 0); 895 896 done2: 897 #ifdef MAC 898 mac_execve_exit(imgp); 899 mac_execve_interpreter_exit(interpvplabel); 900 #endif 901 exec_free_args(args); 902 903 if (error && imgp->vmspace_destroyed) { 904 /* sorry, no more process anymore. exit gracefully */ 905 exit1(td, W_EXITCODE(0, SIGABRT)); 906 /* NOT REACHED */ 907 } 908 909 #ifdef KTRACE 910 if (error == 0) 911 ktrprocctor(p); 912 #endif 913 914 return (error); 915 } 916 917 int 918 exec_map_first_page(imgp) 919 struct image_params *imgp; 920 { 921 int rv, i; 922 int initial_pagein; 923 vm_page_t ma[VM_INITIAL_PAGEIN]; 924 vm_object_t object; 925 926 if (imgp->firstpage != NULL) 927 exec_unmap_first_page(imgp); 928 929 object = imgp->vp->v_object; 930 if (object == NULL) 931 return (EACCES); 932 VM_OBJECT_WLOCK(object); 933 #if VM_NRESERVLEVEL > 0 934 if ((object->flags & OBJ_COLORED) == 0) { 935 object->flags |= OBJ_COLORED; 936 object->pg_color = 0; 937 } 938 #endif 939 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL); 940 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 941 initial_pagein = VM_INITIAL_PAGEIN; 942 if (initial_pagein > object->size) 943 initial_pagein = object->size; 944 for (i = 1; i < initial_pagein; i++) { 945 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 946 if (ma[i]->valid) 947 break; 948 if (vm_page_tryxbusy(ma[i])) 949 break; 950 } else { 951 ma[i] = vm_page_alloc(object, i, 952 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 953 if (ma[i] == NULL) 954 break; 955 } 956 } 957 initial_pagein = i; 958 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 959 ma[0] = vm_page_lookup(object, 0); 960 if ((rv != VM_PAGER_OK) || (ma[0] == NULL)) { 961 if (ma[0] != NULL) { 962 vm_page_lock(ma[0]); 963 vm_page_free(ma[0]); 964 vm_page_unlock(ma[0]); 965 } 966 VM_OBJECT_WUNLOCK(object); 967 return (EIO); 968 } 969 } 970 vm_page_xunbusy(ma[0]); 971 vm_page_lock(ma[0]); 972 vm_page_hold(ma[0]); 973 vm_page_unlock(ma[0]); 974 VM_OBJECT_WUNLOCK(object); 975 976 imgp->firstpage = sf_buf_alloc(ma[0], 0); 977 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 978 979 return (0); 980 } 981 982 void 983 exec_unmap_first_page(imgp) 984 struct image_params *imgp; 985 { 986 vm_page_t m; 987 988 if (imgp->firstpage != NULL) { 989 m = sf_buf_page(imgp->firstpage); 990 sf_buf_free(imgp->firstpage); 991 imgp->firstpage = NULL; 992 vm_page_lock(m); 993 vm_page_unhold(m); 994 vm_page_unlock(m); 995 } 996 } 997 998 /* 999 * Destroy old address space, and allocate a new stack 1000 * The new stack is only SGROWSIZ large because it is grown 1001 * automatically in trap.c. 1002 */ 1003 int 1004 exec_new_vmspace(imgp, sv) 1005 struct image_params *imgp; 1006 struct sysentvec *sv; 1007 { 1008 int error; 1009 struct proc *p = imgp->proc; 1010 struct vmspace *vmspace = p->p_vmspace; 1011 vm_object_t obj; 1012 vm_offset_t sv_minuser, stack_addr; 1013 vm_map_t map; 1014 u_long ssiz; 1015 1016 imgp->vmspace_destroyed = 1; 1017 imgp->sysent = sv; 1018 1019 /* May be called with Giant held */ 1020 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1021 1022 /* 1023 * Blow away entire process VM, if address space not shared, 1024 * otherwise, create a new VM space so that other threads are 1025 * not disrupted 1026 */ 1027 map = &vmspace->vm_map; 1028 if (map_at_zero) 1029 sv_minuser = sv->sv_minuser; 1030 else 1031 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1032 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1033 vm_map_max(map) == sv->sv_maxuser) { 1034 shmexit(vmspace); 1035 pmap_remove_pages(vmspace_pmap(vmspace)); 1036 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1037 } else { 1038 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1039 if (error) 1040 return (error); 1041 vmspace = p->p_vmspace; 1042 map = &vmspace->vm_map; 1043 } 1044 1045 /* Map a shared page */ 1046 obj = sv->sv_shared_page_obj; 1047 if (obj != NULL) { 1048 vm_object_reference(obj); 1049 error = vm_map_fixed(map, obj, 0, 1050 sv->sv_shared_page_base, sv->sv_shared_page_len, 1051 VM_PROT_READ | VM_PROT_EXECUTE, 1052 VM_PROT_READ | VM_PROT_EXECUTE, 1053 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1054 if (error) { 1055 vm_object_deallocate(obj); 1056 return (error); 1057 } 1058 } 1059 1060 /* Allocate a new stack */ 1061 if (sv->sv_maxssiz != NULL) 1062 ssiz = *sv->sv_maxssiz; 1063 else 1064 ssiz = maxssiz; 1065 stack_addr = sv->sv_usrstack - ssiz; 1066 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1067 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1068 sv->sv_stackprot, 1069 VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1070 if (error) 1071 return (error); 1072 1073 #ifdef __ia64__ 1074 /* Allocate a new register stack */ 1075 stack_addr = IA64_BACKINGSTORE; 1076 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1077 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP); 1078 if (error) 1079 return (error); 1080 #endif 1081 1082 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 1083 * VM_STACK case, but they are still used to monitor the size of the 1084 * process stack so we can check the stack rlimit. 1085 */ 1086 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1087 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1088 1089 return (0); 1090 } 1091 1092 /* 1093 * Copy out argument and environment strings from the old process address 1094 * space into the temporary string buffer. 1095 */ 1096 int 1097 exec_copyin_args(struct image_args *args, char *fname, 1098 enum uio_seg segflg, char **argv, char **envv) 1099 { 1100 char *argp, *envp; 1101 int error; 1102 size_t length; 1103 1104 bzero(args, sizeof(*args)); 1105 if (argv == NULL) 1106 return (EFAULT); 1107 1108 /* 1109 * Allocate demand-paged memory for the file name, argument, and 1110 * environment strings. 1111 */ 1112 error = exec_alloc_args(args); 1113 if (error != 0) 1114 return (error); 1115 1116 /* 1117 * Copy the file name. 1118 */ 1119 if (fname != NULL) { 1120 args->fname = args->buf; 1121 error = (segflg == UIO_SYSSPACE) ? 1122 copystr(fname, args->fname, PATH_MAX, &length) : 1123 copyinstr(fname, args->fname, PATH_MAX, &length); 1124 if (error != 0) 1125 goto err_exit; 1126 } else 1127 length = 0; 1128 1129 args->begin_argv = args->buf + length; 1130 args->endp = args->begin_argv; 1131 args->stringspace = ARG_MAX; 1132 1133 /* 1134 * extract arguments first 1135 */ 1136 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 1137 if (argp == (caddr_t) -1) { 1138 error = EFAULT; 1139 goto err_exit; 1140 } 1141 if ((error = copyinstr(argp, args->endp, 1142 args->stringspace, &length))) { 1143 if (error == ENAMETOOLONG) 1144 error = E2BIG; 1145 goto err_exit; 1146 } 1147 args->stringspace -= length; 1148 args->endp += length; 1149 args->argc++; 1150 } 1151 1152 args->begin_envv = args->endp; 1153 1154 /* 1155 * extract environment strings 1156 */ 1157 if (envv) { 1158 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) { 1159 if (envp == (caddr_t)-1) { 1160 error = EFAULT; 1161 goto err_exit; 1162 } 1163 if ((error = copyinstr(envp, args->endp, 1164 args->stringspace, &length))) { 1165 if (error == ENAMETOOLONG) 1166 error = E2BIG; 1167 goto err_exit; 1168 } 1169 args->stringspace -= length; 1170 args->endp += length; 1171 args->envc++; 1172 } 1173 } 1174 1175 return (0); 1176 1177 err_exit: 1178 exec_free_args(args); 1179 return (error); 1180 } 1181 1182 /* 1183 * Allocate temporary demand-paged, zero-filled memory for the file name, 1184 * argument, and environment strings. Returns zero if the allocation succeeds 1185 * and ENOMEM otherwise. 1186 */ 1187 int 1188 exec_alloc_args(struct image_args *args) 1189 { 1190 1191 args->buf = (char *)kmap_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 1192 return (args->buf != NULL ? 0 : ENOMEM); 1193 } 1194 1195 void 1196 exec_free_args(struct image_args *args) 1197 { 1198 1199 if (args->buf != NULL) { 1200 kmap_free_wakeup(exec_map, (vm_offset_t)args->buf, 1201 PATH_MAX + ARG_MAX); 1202 args->buf = NULL; 1203 } 1204 if (args->fname_buf != NULL) { 1205 free(args->fname_buf, M_TEMP); 1206 args->fname_buf = NULL; 1207 } 1208 } 1209 1210 /* 1211 * Copy strings out to the new process address space, constructing new arg 1212 * and env vector tables. Return a pointer to the base so that it can be used 1213 * as the initial stack pointer. 1214 */ 1215 register_t * 1216 exec_copyout_strings(imgp) 1217 struct image_params *imgp; 1218 { 1219 int argc, envc; 1220 char **vectp; 1221 char *stringp, *destp; 1222 register_t *stack_base; 1223 struct ps_strings *arginfo; 1224 struct proc *p; 1225 size_t execpath_len; 1226 int szsigcode, szps; 1227 char canary[sizeof(long) * 8]; 1228 1229 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1230 /* 1231 * Calculate string base and vector table pointers. 1232 * Also deal with signal trampoline code for this exec type. 1233 */ 1234 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1235 execpath_len = strlen(imgp->execpath) + 1; 1236 else 1237 execpath_len = 0; 1238 p = imgp->proc; 1239 szsigcode = 0; 1240 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1241 if (p->p_sysent->sv_sigcode_base == 0) { 1242 if (p->p_sysent->sv_szsigcode != NULL) 1243 szsigcode = *(p->p_sysent->sv_szsigcode); 1244 } 1245 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 1246 roundup(execpath_len, sizeof(char *)) - 1247 roundup(sizeof(canary), sizeof(char *)) - 1248 roundup(szps, sizeof(char *)) - 1249 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *)); 1250 1251 /* 1252 * install sigcode 1253 */ 1254 if (szsigcode != 0) 1255 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo - 1256 szsigcode), szsigcode); 1257 1258 /* 1259 * Copy the image path for the rtld. 1260 */ 1261 if (execpath_len != 0) { 1262 imgp->execpathp = (uintptr_t)arginfo - szsigcode - execpath_len; 1263 copyout(imgp->execpath, (void *)imgp->execpathp, 1264 execpath_len); 1265 } 1266 1267 /* 1268 * Prepare the canary for SSP. 1269 */ 1270 arc4rand(canary, sizeof(canary), 0); 1271 imgp->canary = (uintptr_t)arginfo - szsigcode - execpath_len - 1272 sizeof(canary); 1273 copyout(canary, (void *)imgp->canary, sizeof(canary)); 1274 imgp->canarylen = sizeof(canary); 1275 1276 /* 1277 * Prepare the pagesizes array. 1278 */ 1279 imgp->pagesizes = (uintptr_t)arginfo - szsigcode - execpath_len - 1280 roundup(sizeof(canary), sizeof(char *)) - szps; 1281 copyout(pagesizes, (void *)imgp->pagesizes, szps); 1282 imgp->pagesizeslen = szps; 1283 1284 /* 1285 * If we have a valid auxargs ptr, prepare some room 1286 * on the stack. 1287 */ 1288 if (imgp->auxargs) { 1289 /* 1290 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1291 * lower compatibility. 1292 */ 1293 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1294 (AT_COUNT * 2); 1295 /* 1296 * The '+ 2' is for the null pointers at the end of each of 1297 * the arg and env vector sets,and imgp->auxarg_size is room 1298 * for argument of Runtime loader. 1299 */ 1300 vectp = (char **)(destp - (imgp->args->argc + 1301 imgp->args->envc + 2 + imgp->auxarg_size) 1302 * sizeof(char *)); 1303 } else { 1304 /* 1305 * The '+ 2' is for the null pointers at the end of each of 1306 * the arg and env vector sets 1307 */ 1308 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) * 1309 sizeof(char *)); 1310 } 1311 1312 /* 1313 * vectp also becomes our initial stack base 1314 */ 1315 stack_base = (register_t *)vectp; 1316 1317 stringp = imgp->args->begin_argv; 1318 argc = imgp->args->argc; 1319 envc = imgp->args->envc; 1320 1321 /* 1322 * Copy out strings - arguments and environment. 1323 */ 1324 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace); 1325 1326 /* 1327 * Fill in "ps_strings" struct for ps, w, etc. 1328 */ 1329 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1330 suword32(&arginfo->ps_nargvstr, argc); 1331 1332 /* 1333 * Fill in argument portion of vector table. 1334 */ 1335 for (; argc > 0; --argc) { 1336 suword(vectp++, (long)(intptr_t)destp); 1337 while (*stringp++ != 0) 1338 destp++; 1339 destp++; 1340 } 1341 1342 /* a null vector table pointer separates the argp's from the envp's */ 1343 suword(vectp++, 0); 1344 1345 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1346 suword32(&arginfo->ps_nenvstr, envc); 1347 1348 /* 1349 * Fill in environment portion of vector table. 1350 */ 1351 for (; envc > 0; --envc) { 1352 suword(vectp++, (long)(intptr_t)destp); 1353 while (*stringp++ != 0) 1354 destp++; 1355 destp++; 1356 } 1357 1358 /* end of vector table is a null pointer */ 1359 suword(vectp, 0); 1360 1361 return (stack_base); 1362 } 1363 1364 /* 1365 * Check permissions of file to execute. 1366 * Called with imgp->vp locked. 1367 * Return 0 for success or error code on failure. 1368 */ 1369 int 1370 exec_check_permissions(imgp) 1371 struct image_params *imgp; 1372 { 1373 struct vnode *vp = imgp->vp; 1374 struct vattr *attr = imgp->attr; 1375 struct thread *td; 1376 int error, writecount; 1377 1378 td = curthread; 1379 1380 /* Get file attributes */ 1381 error = VOP_GETATTR(vp, attr, td->td_ucred); 1382 if (error) 1383 return (error); 1384 1385 #ifdef MAC 1386 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1387 if (error) 1388 return (error); 1389 #endif 1390 1391 /* 1392 * 1) Check if file execution is disabled for the filesystem that 1393 * this file resides on. 1394 * 2) Ensure that at least one execute bit is on. Otherwise, a 1395 * privileged user will always succeed, and we don't want this 1396 * to happen unless the file really is executable. 1397 * 3) Ensure that the file is a regular file. 1398 */ 1399 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1400 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1401 (attr->va_type != VREG)) 1402 return (EACCES); 1403 1404 /* 1405 * Zero length files can't be exec'd 1406 */ 1407 if (attr->va_size == 0) 1408 return (ENOEXEC); 1409 1410 /* 1411 * Check for execute permission to file based on current credentials. 1412 */ 1413 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1414 if (error) 1415 return (error); 1416 1417 /* 1418 * Check number of open-for-writes on the file and deny execution 1419 * if there are any. 1420 */ 1421 error = VOP_GET_WRITECOUNT(vp, &writecount); 1422 if (error != 0) 1423 return (error); 1424 if (writecount != 0) 1425 return (ETXTBSY); 1426 1427 /* 1428 * Call filesystem specific open routine (which does nothing in the 1429 * general case). 1430 */ 1431 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1432 if (error == 0) 1433 imgp->opened = 1; 1434 return (error); 1435 } 1436 1437 /* 1438 * Exec handler registration 1439 */ 1440 int 1441 exec_register(execsw_arg) 1442 const struct execsw *execsw_arg; 1443 { 1444 const struct execsw **es, **xs, **newexecsw; 1445 int count = 2; /* New slot and trailing NULL */ 1446 1447 if (execsw) 1448 for (es = execsw; *es; es++) 1449 count++; 1450 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1451 if (newexecsw == NULL) 1452 return (ENOMEM); 1453 xs = newexecsw; 1454 if (execsw) 1455 for (es = execsw; *es; es++) 1456 *xs++ = *es; 1457 *xs++ = execsw_arg; 1458 *xs = NULL; 1459 if (execsw) 1460 free(execsw, M_TEMP); 1461 execsw = newexecsw; 1462 return (0); 1463 } 1464 1465 int 1466 exec_unregister(execsw_arg) 1467 const struct execsw *execsw_arg; 1468 { 1469 const struct execsw **es, **xs, **newexecsw; 1470 int count = 1; 1471 1472 if (execsw == NULL) 1473 panic("unregister with no handlers left?\n"); 1474 1475 for (es = execsw; *es; es++) { 1476 if (*es == execsw_arg) 1477 break; 1478 } 1479 if (*es == NULL) 1480 return (ENOENT); 1481 for (es = execsw; *es; es++) 1482 if (*es != execsw_arg) 1483 count++; 1484 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1485 if (newexecsw == NULL) 1486 return (ENOMEM); 1487 xs = newexecsw; 1488 for (es = execsw; *es; es++) 1489 if (*es != execsw_arg) 1490 *xs++ = *es; 1491 *xs = NULL; 1492 if (execsw) 1493 free(execsw, M_TEMP); 1494 execsw = newexecsw; 1495 return (0); 1496 } 1497