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