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/sched.h> 61 #include <sys/sdt.h> 62 #include <sys/sf_buf.h> 63 #include <sys/syscallsubr.h> 64 #include <sys/sysent.h> 65 #include <sys/shm.h> 66 #include <sys/sysctl.h> 67 #include <sys/vnode.h> 68 #include <sys/stat.h> 69 #ifdef KTRACE 70 #include <sys/ktrace.h> 71 #endif 72 73 #include <vm/vm.h> 74 #include <vm/vm_param.h> 75 #include <vm/pmap.h> 76 #include <vm/vm_page.h> 77 #include <vm/vm_map.h> 78 #include <vm/vm_kern.h> 79 #include <vm/vm_extern.h> 80 #include <vm/vm_object.h> 81 #include <vm/vm_pager.h> 82 83 #ifdef HWPMC_HOOKS 84 #include <sys/pmckern.h> 85 #endif 86 87 #include <machine/reg.h> 88 89 #include <security/audit/audit.h> 90 #include <security/mac/mac_framework.h> 91 92 #ifdef KDTRACE_HOOKS 93 #include <sys/dtrace_bsd.h> 94 dtrace_execexit_func_t dtrace_fasttrap_exec; 95 #endif 96 97 SDT_PROVIDER_DECLARE(proc); 98 SDT_PROBE_DEFINE(proc, kernel, , exec, exec); 99 SDT_PROBE_ARGTYPE(proc, kernel, , exec, 0, "char *"); 100 SDT_PROBE_DEFINE(proc, kernel, , exec_failure, exec-failure); 101 SDT_PROBE_ARGTYPE(proc, kernel, , exec_failure, 0, "int"); 102 SDT_PROBE_DEFINE(proc, kernel, , exec_success, exec-success); 103 SDT_PROBE_ARGTYPE(proc, kernel, , exec_success, 0, "char *"); 104 105 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 106 107 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 108 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 109 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 110 static int do_execve(struct thread *td, struct image_args *args, 111 struct mac *mac_p); 112 113 /* XXX This should be vm_size_t. */ 114 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD, 115 NULL, 0, sysctl_kern_ps_strings, "LU", ""); 116 117 /* XXX This should be vm_size_t. */ 118 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 119 CTLFLAG_CAPRD, NULL, 0, sysctl_kern_usrstack, "LU", ""); 120 121 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 122 NULL, 0, sysctl_kern_stackprot, "I", ""); 123 124 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 125 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 126 &ps_arg_cache_limit, 0, ""); 127 128 static int map_at_zero = 0; 129 TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero); 130 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &map_at_zero, 0, 131 "Permit processes to map an object at virtual address 0."); 132 133 static int 134 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 135 { 136 struct proc *p; 137 int error; 138 139 p = curproc; 140 #ifdef SCTL_MASK32 141 if (req->flags & SCTL_MASK32) { 142 unsigned int val; 143 val = (unsigned int)p->p_sysent->sv_psstrings; 144 error = SYSCTL_OUT(req, &val, sizeof(val)); 145 } else 146 #endif 147 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 148 sizeof(p->p_sysent->sv_psstrings)); 149 return error; 150 } 151 152 static int 153 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 154 { 155 struct proc *p; 156 int error; 157 158 p = curproc; 159 #ifdef SCTL_MASK32 160 if (req->flags & SCTL_MASK32) { 161 unsigned int val; 162 val = (unsigned int)p->p_sysent->sv_usrstack; 163 error = SYSCTL_OUT(req, &val, sizeof(val)); 164 } else 165 #endif 166 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 167 sizeof(p->p_sysent->sv_usrstack)); 168 return error; 169 } 170 171 static int 172 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 173 { 174 struct proc *p; 175 176 p = curproc; 177 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 178 sizeof(p->p_sysent->sv_stackprot))); 179 } 180 181 /* 182 * Each of the items is a pointer to a `const struct execsw', hence the 183 * double pointer here. 184 */ 185 static const struct execsw **execsw; 186 187 #ifndef _SYS_SYSPROTO_H_ 188 struct execve_args { 189 char *fname; 190 char **argv; 191 char **envv; 192 }; 193 #endif 194 195 int 196 sys_execve(td, uap) 197 struct thread *td; 198 struct execve_args /* { 199 char *fname; 200 char **argv; 201 char **envv; 202 } */ *uap; 203 { 204 int error; 205 struct image_args args; 206 207 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 208 uap->argv, uap->envv); 209 if (error == 0) 210 error = kern_execve(td, &args, NULL); 211 return (error); 212 } 213 214 #ifndef _SYS_SYSPROTO_H_ 215 struct fexecve_args { 216 int fd; 217 char **argv; 218 char **envv; 219 } 220 #endif 221 int 222 sys_fexecve(struct thread *td, struct fexecve_args *uap) 223 { 224 int error; 225 struct image_args args; 226 227 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 228 uap->argv, uap->envv); 229 if (error == 0) { 230 args.fd = uap->fd; 231 error = kern_execve(td, &args, NULL); 232 } 233 return (error); 234 } 235 236 #ifndef _SYS_SYSPROTO_H_ 237 struct __mac_execve_args { 238 char *fname; 239 char **argv; 240 char **envv; 241 struct mac *mac_p; 242 }; 243 #endif 244 245 int 246 sys___mac_execve(td, uap) 247 struct thread *td; 248 struct __mac_execve_args /* { 249 char *fname; 250 char **argv; 251 char **envv; 252 struct mac *mac_p; 253 } */ *uap; 254 { 255 #ifdef MAC 256 int error; 257 struct image_args args; 258 259 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 260 uap->argv, uap->envv); 261 if (error == 0) 262 error = kern_execve(td, &args, uap->mac_p); 263 return (error); 264 #else 265 return (ENOSYS); 266 #endif 267 } 268 269 /* 270 * XXX: kern_execve has the astonishing property of not always returning to 271 * the caller. If sufficiently bad things happen during the call to 272 * do_execve(), it can end up calling exit1(); as a result, callers must 273 * avoid doing anything which they might need to undo (e.g., allocating 274 * memory). 275 */ 276 int 277 kern_execve(td, args, mac_p) 278 struct thread *td; 279 struct image_args *args; 280 struct mac *mac_p; 281 { 282 struct proc *p = td->td_proc; 283 int error; 284 285 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 286 args->begin_envv - args->begin_argv); 287 AUDIT_ARG_ENVV(args->begin_envv, args->envc, 288 args->endp - args->begin_envv); 289 if (p->p_flag & P_HADTHREADS) { 290 PROC_LOCK(p); 291 if (thread_single(SINGLE_BOUNDARY)) { 292 PROC_UNLOCK(p); 293 exec_free_args(args); 294 return (ERESTART); /* Try again later. */ 295 } 296 PROC_UNLOCK(p); 297 } 298 299 error = do_execve(td, args, mac_p); 300 301 if (p->p_flag & P_HADTHREADS) { 302 PROC_LOCK(p); 303 /* 304 * If success, we upgrade to SINGLE_EXIT state to 305 * force other threads to suicide. 306 */ 307 if (error == 0) 308 thread_single(SINGLE_EXIT); 309 else 310 thread_single_end(); 311 PROC_UNLOCK(p); 312 } 313 314 return (error); 315 } 316 317 /* 318 * In-kernel implementation of execve(). All arguments are assumed to be 319 * userspace pointers from the passed thread. 320 */ 321 static int 322 do_execve(td, args, mac_p) 323 struct thread *td; 324 struct image_args *args; 325 struct mac *mac_p; 326 { 327 struct proc *p = td->td_proc; 328 struct nameidata nd; 329 struct ucred *newcred = NULL, *oldcred; 330 struct uidinfo *euip; 331 register_t *stack_base; 332 int error, i; 333 struct image_params image_params, *imgp; 334 struct vattr attr; 335 int (*img_first)(struct image_params *); 336 struct pargs *oldargs = NULL, *newargs = NULL; 337 struct sigacts *oldsigacts, *newsigacts; 338 #ifdef KTRACE 339 struct vnode *tracevp = NULL; 340 struct ucred *tracecred = NULL; 341 #endif 342 struct vnode *textvp = NULL, *binvp = NULL; 343 int credential_changing; 344 int textset; 345 #ifdef MAC 346 struct label *interpvplabel = NULL; 347 int will_transition; 348 #endif 349 #ifdef HWPMC_HOOKS 350 struct pmckern_procexec pe; 351 #endif 352 static const char fexecv_proc_title[] = "(fexecv)"; 353 354 imgp = &image_params; 355 356 /* 357 * Lock the process and set the P_INEXEC flag to indicate that 358 * it should be left alone until we're done here. This is 359 * necessary to avoid race conditions - e.g. in ptrace() - 360 * that might allow a local user to illicitly obtain elevated 361 * privileges. 362 */ 363 PROC_LOCK(p); 364 KASSERT((p->p_flag & P_INEXEC) == 0, 365 ("%s(): process already has P_INEXEC flag", __func__)); 366 p->p_flag |= P_INEXEC; 367 PROC_UNLOCK(p); 368 369 /* 370 * Initialize part of the common data 371 */ 372 imgp->proc = p; 373 imgp->execlabel = NULL; 374 imgp->attr = &attr; 375 imgp->entry_addr = 0; 376 imgp->reloc_base = 0; 377 imgp->vmspace_destroyed = 0; 378 imgp->interpreted = 0; 379 imgp->opened = 0; 380 imgp->interpreter_name = NULL; 381 imgp->auxargs = NULL; 382 imgp->vp = NULL; 383 imgp->object = NULL; 384 imgp->firstpage = NULL; 385 imgp->ps_strings = 0; 386 imgp->auxarg_size = 0; 387 imgp->args = args; 388 imgp->execpath = imgp->freepath = NULL; 389 imgp->execpathp = 0; 390 imgp->canary = 0; 391 imgp->canarylen = 0; 392 imgp->pagesizes = 0; 393 imgp->pagesizeslen = 0; 394 imgp->stack_prot = 0; 395 396 #ifdef MAC 397 error = mac_execve_enter(imgp, mac_p); 398 if (error) 399 goto exec_fail; 400 #endif 401 402 imgp->image_header = NULL; 403 404 /* 405 * Translate the file name. namei() returns a vnode pointer 406 * in ni_vp amoung other things. 407 * 408 * XXXAUDIT: It would be desirable to also audit the name of the 409 * interpreter if this is an interpreted binary. 410 */ 411 if (args->fname != NULL) { 412 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 413 | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 414 } 415 416 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 417 418 interpret: 419 if (args->fname != NULL) { 420 #ifdef CAPABILITY_MODE 421 /* 422 * While capability mode can't reach this point via direct 423 * path arguments to execve(), we also don't allow 424 * interpreters to be used in capability mode (for now). 425 * Catch indirect lookups and return a permissions error. 426 */ 427 if (IN_CAPABILITY_MODE(td)) { 428 error = ECAPMODE; 429 goto exec_fail; 430 } 431 #endif 432 error = namei(&nd); 433 if (error) 434 goto exec_fail; 435 436 binvp = nd.ni_vp; 437 imgp->vp = binvp; 438 } else { 439 AUDIT_ARG_FD(args->fd); 440 /* 441 * Some might argue that CAP_READ and/or CAP_MMAP should also 442 * be required here; such arguments will be entertained. 443 * 444 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 445 */ 446 error = fgetvp_exec(td, args->fd, CAP_FEXECVE, &binvp); 447 if (error) 448 goto exec_fail; 449 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY); 450 AUDIT_ARG_VNODE1(binvp); 451 imgp->vp = binvp; 452 } 453 454 /* 455 * Check file permissions (also 'opens' file) 456 */ 457 error = exec_check_permissions(imgp); 458 if (error) 459 goto exec_fail_dealloc; 460 461 imgp->object = imgp->vp->v_object; 462 if (imgp->object != NULL) 463 vm_object_reference(imgp->object); 464 465 /* 466 * Set VV_TEXT now so no one can write to the executable while we're 467 * activating it. 468 * 469 * Remember if this was set before and unset it in case this is not 470 * actually an executable image. 471 */ 472 textset = VOP_IS_TEXT(imgp->vp); 473 VOP_SET_TEXT(imgp->vp); 474 475 error = exec_map_first_page(imgp); 476 if (error) 477 goto exec_fail_dealloc; 478 479 imgp->proc->p_osrel = 0; 480 /* 481 * If the current process has a special image activator it 482 * wants to try first, call it. For example, emulating shell 483 * scripts differently. 484 */ 485 error = -1; 486 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 487 error = img_first(imgp); 488 489 /* 490 * Loop through the list of image activators, calling each one. 491 * An activator returns -1 if there is no match, 0 on success, 492 * and an error otherwise. 493 */ 494 for (i = 0; error == -1 && execsw[i]; ++i) { 495 if (execsw[i]->ex_imgact == NULL || 496 execsw[i]->ex_imgact == img_first) { 497 continue; 498 } 499 error = (*execsw[i]->ex_imgact)(imgp); 500 } 501 502 if (error) { 503 if (error == -1) { 504 if (textset == 0) 505 VOP_UNSET_TEXT(imgp->vp); 506 error = ENOEXEC; 507 } 508 goto exec_fail_dealloc; 509 } 510 511 /* 512 * Special interpreter operation, cleanup and loop up to try to 513 * activate the interpreter. 514 */ 515 if (imgp->interpreted) { 516 exec_unmap_first_page(imgp); 517 /* 518 * VV_TEXT needs to be unset for scripts. There is a short 519 * period before we determine that something is a script where 520 * VV_TEXT will be set. The vnode lock is held over this 521 * entire period so nothing should illegitimately be blocked. 522 */ 523 VOP_UNSET_TEXT(imgp->vp); 524 /* free name buffer and old vnode */ 525 if (args->fname != NULL) 526 NDFREE(&nd, NDF_ONLY_PNBUF); 527 #ifdef MAC 528 mac_execve_interpreter_enter(binvp, &interpvplabel); 529 #endif 530 if (imgp->opened) { 531 VOP_CLOSE(binvp, FREAD, td->td_ucred, td); 532 imgp->opened = 0; 533 } 534 vput(binvp); 535 vm_object_deallocate(imgp->object); 536 imgp->object = NULL; 537 /* set new name to that of the interpreter */ 538 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 539 UIO_SYSSPACE, imgp->interpreter_name, td); 540 args->fname = imgp->interpreter_name; 541 goto interpret; 542 } 543 544 /* 545 * NB: We unlock the vnode here because it is believed that none 546 * of the sv_copyout_strings/sv_fixup operations require the vnode. 547 */ 548 VOP_UNLOCK(imgp->vp, 0); 549 550 /* 551 * Do the best to calculate the full path to the image file. 552 */ 553 if (imgp->auxargs != NULL && 554 ((args->fname != NULL && args->fname[0] == '/') || 555 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0)) 556 imgp->execpath = args->fname; 557 558 /* 559 * Copy out strings (args and env) and initialize stack base 560 */ 561 if (p->p_sysent->sv_copyout_strings) 562 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 563 else 564 stack_base = exec_copyout_strings(imgp); 565 566 /* 567 * If custom stack fixup routine present for this process 568 * let it do the stack setup. 569 * Else stuff argument count as first item on stack 570 */ 571 if (p->p_sysent->sv_fixup != NULL) 572 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 573 else 574 suword(--stack_base, imgp->args->argc); 575 576 /* 577 * For security and other reasons, the file descriptor table cannot 578 * be shared after an exec. 579 */ 580 fdunshare(p, td); 581 582 /* 583 * Malloc things before we need locks. 584 */ 585 newcred = crget(); 586 euip = uifind(attr.va_uid); 587 i = imgp->args->begin_envv - imgp->args->begin_argv; 588 /* Cache arguments if they fit inside our allowance */ 589 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 590 newargs = pargs_alloc(i); 591 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 592 } 593 594 /* close files on exec */ 595 fdcloseexec(td); 596 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 597 598 /* Get a reference to the vnode prior to locking the proc */ 599 VREF(binvp); 600 601 /* 602 * For security and other reasons, signal handlers cannot 603 * be shared after an exec. The new process gets a copy of the old 604 * handlers. In execsigs(), the new process will have its signals 605 * reset. 606 */ 607 PROC_LOCK(p); 608 oldcred = crcopysafe(p, newcred); 609 if (sigacts_shared(p->p_sigacts)) { 610 oldsigacts = p->p_sigacts; 611 PROC_UNLOCK(p); 612 newsigacts = sigacts_alloc(); 613 sigacts_copy(newsigacts, oldsigacts); 614 PROC_LOCK(p); 615 p->p_sigacts = newsigacts; 616 } else 617 oldsigacts = NULL; 618 619 /* Stop profiling */ 620 stopprofclock(p); 621 622 /* reset caught signals */ 623 execsigs(p); 624 625 /* name this process - nameiexec(p, ndp) */ 626 bzero(p->p_comm, sizeof(p->p_comm)); 627 if (args->fname) 628 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 629 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 630 else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0) 631 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 632 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 633 #ifdef KTR 634 sched_clear_tdname(td); 635 #endif 636 637 /* 638 * mark as execed, wakeup the process that vforked (if any) and tell 639 * it that it now has its own resources back 640 */ 641 p->p_flag |= P_EXEC; 642 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 643 p->p_flag &= ~P_PPWAIT; 644 cv_broadcast(&p->p_pwait); 645 } 646 647 /* 648 * Implement image setuid/setgid. 649 * 650 * Don't honor setuid/setgid if the filesystem prohibits it or if 651 * the process is being traced. 652 * 653 * We disable setuid/setgid/etc in compatibility mode on the basis 654 * that most setugid applications are not written with that 655 * environment in mind, and will therefore almost certainly operate 656 * incorrectly. In principle there's no reason that setugid 657 * applications might not be useful in capability mode, so we may want 658 * to reconsider this conservative design choice in the future. 659 * 660 * XXXMAC: For the time being, use NOSUID to also prohibit 661 * transitions on the file system. 662 */ 663 credential_changing = 0; 664 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 665 attr.va_uid; 666 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 667 attr.va_gid; 668 #ifdef MAC 669 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 670 interpvplabel, imgp); 671 credential_changing |= will_transition; 672 #endif 673 674 if (credential_changing && 675 #ifdef CAPABILITY_MODE 676 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 677 #endif 678 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 679 (p->p_flag & P_TRACED) == 0) { 680 /* 681 * Turn off syscall tracing for set-id programs, except for 682 * root. Record any set-id flags first to make sure that 683 * we do not regain any tracing during a possible block. 684 */ 685 setsugid(p); 686 687 #ifdef KTRACE 688 if (p->p_tracecred != NULL && 689 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0)) 690 ktrprocexec(p, &tracecred, &tracevp); 691 #endif 692 /* 693 * Close any file descriptors 0..2 that reference procfs, 694 * then make sure file descriptors 0..2 are in use. 695 * 696 * setugidsafety() may call closef() and then pfind() 697 * which may grab the process lock. 698 * fdcheckstd() may call falloc() which may block to 699 * allocate memory, so temporarily drop the process lock. 700 */ 701 PROC_UNLOCK(p); 702 VOP_UNLOCK(imgp->vp, 0); 703 setugidsafety(td); 704 error = fdcheckstd(td); 705 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 706 if (error != 0) 707 goto done1; 708 PROC_LOCK(p); 709 /* 710 * Set the new credentials. 711 */ 712 if (attr.va_mode & S_ISUID) 713 change_euid(newcred, euip); 714 if (attr.va_mode & S_ISGID) 715 change_egid(newcred, attr.va_gid); 716 #ifdef MAC 717 if (will_transition) { 718 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 719 interpvplabel, imgp); 720 } 721 #endif 722 /* 723 * Implement correct POSIX saved-id behavior. 724 * 725 * XXXMAC: Note that the current logic will save the 726 * uid and gid if a MAC domain transition occurs, even 727 * though maybe it shouldn't. 728 */ 729 change_svuid(newcred, newcred->cr_uid); 730 change_svgid(newcred, newcred->cr_gid); 731 p->p_ucred = newcred; 732 newcred = NULL; 733 } else { 734 if (oldcred->cr_uid == oldcred->cr_ruid && 735 oldcred->cr_gid == oldcred->cr_rgid) 736 p->p_flag &= ~P_SUGID; 737 /* 738 * Implement correct POSIX saved-id behavior. 739 * 740 * XXX: It's not clear that the existing behavior is 741 * POSIX-compliant. A number of sources indicate that the 742 * saved uid/gid should only be updated if the new ruid is 743 * not equal to the old ruid, or the new euid is not equal 744 * to the old euid and the new euid is not equal to the old 745 * ruid. The FreeBSD code always updates the saved uid/gid. 746 * Also, this code uses the new (replaced) euid and egid as 747 * the source, which may or may not be the right ones to use. 748 */ 749 if (oldcred->cr_svuid != oldcred->cr_uid || 750 oldcred->cr_svgid != oldcred->cr_gid) { 751 change_svuid(newcred, newcred->cr_uid); 752 change_svgid(newcred, newcred->cr_gid); 753 p->p_ucred = newcred; 754 newcred = NULL; 755 } 756 } 757 758 /* 759 * Store the vp for use in procfs. This vnode was referenced prior 760 * to locking the proc lock. 761 */ 762 textvp = p->p_textvp; 763 p->p_textvp = binvp; 764 765 #ifdef KDTRACE_HOOKS 766 /* 767 * Tell the DTrace fasttrap provider about the exec if it 768 * has declared an interest. 769 */ 770 if (dtrace_fasttrap_exec) 771 dtrace_fasttrap_exec(p); 772 #endif 773 774 /* 775 * Notify others that we exec'd, and clear the P_INEXEC flag 776 * as we're now a bona fide freshly-execed process. 777 */ 778 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 779 p->p_flag &= ~P_INEXEC; 780 781 /* clear "fork but no exec" flag, as we _are_ execing */ 782 p->p_acflag &= ~AFORK; 783 784 /* 785 * Free any previous argument cache and replace it with 786 * the new argument cache, if any. 787 */ 788 oldargs = p->p_args; 789 p->p_args = newargs; 790 newargs = NULL; 791 792 #ifdef HWPMC_HOOKS 793 /* 794 * Check if system-wide sampling is in effect or if the 795 * current process is using PMCs. If so, do exec() time 796 * processing. This processing needs to happen AFTER the 797 * P_INEXEC flag is cleared. 798 * 799 * The proc lock needs to be released before taking the PMC 800 * SX. 801 */ 802 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 803 PROC_UNLOCK(p); 804 VOP_UNLOCK(imgp->vp, 0); 805 pe.pm_credentialschanged = credential_changing; 806 pe.pm_entryaddr = imgp->entry_addr; 807 808 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 809 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 810 } else 811 PROC_UNLOCK(p); 812 #else /* !HWPMC_HOOKS */ 813 PROC_UNLOCK(p); 814 #endif 815 816 /* Set values passed into the program in registers. */ 817 if (p->p_sysent->sv_setregs) 818 (*p->p_sysent->sv_setregs)(td, imgp, 819 (u_long)(uintptr_t)stack_base); 820 else 821 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 822 823 vfs_mark_atime(imgp->vp, td->td_ucred); 824 825 SDT_PROBE(proc, kernel, , exec_success, args->fname, 0, 0, 0, 0); 826 827 done1: 828 /* 829 * Free any resources malloc'd earlier that we didn't use. 830 */ 831 uifree(euip); 832 if (newcred == NULL) 833 crfree(oldcred); 834 else 835 crfree(newcred); 836 VOP_UNLOCK(imgp->vp, 0); 837 838 /* 839 * Handle deferred decrement of ref counts. 840 */ 841 if (textvp != NULL) 842 vrele(textvp); 843 if (binvp && error != 0) 844 vrele(binvp); 845 #ifdef KTRACE 846 if (tracevp != NULL) 847 vrele(tracevp); 848 if (tracecred != NULL) 849 crfree(tracecred); 850 #endif 851 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 852 pargs_drop(oldargs); 853 pargs_drop(newargs); 854 if (oldsigacts != NULL) 855 sigacts_free(oldsigacts); 856 857 exec_fail_dealloc: 858 859 /* 860 * free various allocated resources 861 */ 862 if (imgp->firstpage != NULL) 863 exec_unmap_first_page(imgp); 864 865 if (imgp->vp != NULL) { 866 if (args->fname) 867 NDFREE(&nd, NDF_ONLY_PNBUF); 868 if (imgp->opened) 869 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 870 vput(imgp->vp); 871 } 872 873 if (imgp->object != NULL) 874 vm_object_deallocate(imgp->object); 875 876 free(imgp->freepath, M_TEMP); 877 878 if (error == 0) { 879 PROC_LOCK(p); 880 td->td_dbgflags |= TDB_EXEC; 881 PROC_UNLOCK(p); 882 883 /* 884 * Stop the process here if its stop event mask has 885 * the S_EXEC bit set. 886 */ 887 STOPEVENT(p, S_EXEC, 0); 888 goto done2; 889 } 890 891 exec_fail: 892 /* we're done here, clear P_INEXEC */ 893 PROC_LOCK(p); 894 p->p_flag &= ~P_INEXEC; 895 PROC_UNLOCK(p); 896 897 SDT_PROBE(proc, kernel, , exec_failure, error, 0, 0, 0, 0); 898 899 done2: 900 #ifdef MAC 901 mac_execve_exit(imgp); 902 mac_execve_interpreter_exit(interpvplabel); 903 #endif 904 exec_free_args(args); 905 906 if (error && imgp->vmspace_destroyed) { 907 /* sorry, no more process anymore. exit gracefully */ 908 exit1(td, W_EXITCODE(0, SIGABRT)); 909 /* NOT REACHED */ 910 } 911 912 #ifdef KTRACE 913 if (error == 0) 914 ktrprocctor(p); 915 #endif 916 917 return (error); 918 } 919 920 int 921 exec_map_first_page(imgp) 922 struct image_params *imgp; 923 { 924 int rv, i; 925 int initial_pagein; 926 vm_page_t ma[VM_INITIAL_PAGEIN]; 927 vm_object_t object; 928 929 if (imgp->firstpage != NULL) 930 exec_unmap_first_page(imgp); 931 932 object = imgp->vp->v_object; 933 if (object == NULL) 934 return (EACCES); 935 VM_OBJECT_LOCK(object); 936 #if VM_NRESERVLEVEL > 0 937 if ((object->flags & OBJ_COLORED) == 0) { 938 object->flags |= OBJ_COLORED; 939 object->pg_color = 0; 940 } 941 #endif 942 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 943 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 944 initial_pagein = VM_INITIAL_PAGEIN; 945 if (initial_pagein > object->size) 946 initial_pagein = object->size; 947 for (i = 1; i < initial_pagein; i++) { 948 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 949 if (ma[i]->valid) 950 break; 951 if ((ma[i]->oflags & VPO_BUSY) || ma[i]->busy) 952 break; 953 vm_page_busy(ma[i]); 954 } else { 955 ma[i] = vm_page_alloc(object, i, 956 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 957 if (ma[i] == NULL) 958 break; 959 } 960 } 961 initial_pagein = i; 962 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 963 ma[0] = vm_page_lookup(object, 0); 964 if ((rv != VM_PAGER_OK) || (ma[0] == NULL)) { 965 if (ma[0] != NULL) { 966 vm_page_lock(ma[0]); 967 vm_page_free(ma[0]); 968 vm_page_unlock(ma[0]); 969 } 970 VM_OBJECT_UNLOCK(object); 971 return (EIO); 972 } 973 } 974 vm_page_lock(ma[0]); 975 vm_page_hold(ma[0]); 976 vm_page_unlock(ma[0]); 977 vm_page_wakeup(ma[0]); 978 VM_OBJECT_UNLOCK(object); 979 980 imgp->firstpage = sf_buf_alloc(ma[0], 0); 981 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 982 983 return (0); 984 } 985 986 void 987 exec_unmap_first_page(imgp) 988 struct image_params *imgp; 989 { 990 vm_page_t m; 991 992 if (imgp->firstpage != NULL) { 993 m = sf_buf_page(imgp->firstpage); 994 sf_buf_free(imgp->firstpage); 995 imgp->firstpage = NULL; 996 vm_page_lock(m); 997 vm_page_unhold(m); 998 vm_page_unlock(m); 999 } 1000 } 1001 1002 /* 1003 * Destroy old address space, and allocate a new stack 1004 * The new stack is only SGROWSIZ large because it is grown 1005 * automatically in trap.c. 1006 */ 1007 int 1008 exec_new_vmspace(imgp, sv) 1009 struct image_params *imgp; 1010 struct sysentvec *sv; 1011 { 1012 int error; 1013 struct proc *p = imgp->proc; 1014 struct vmspace *vmspace = p->p_vmspace; 1015 vm_object_t obj; 1016 vm_offset_t sv_minuser, stack_addr; 1017 vm_map_t map; 1018 u_long ssiz; 1019 1020 imgp->vmspace_destroyed = 1; 1021 imgp->sysent = sv; 1022 1023 /* May be called with Giant held */ 1024 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1025 1026 /* 1027 * Blow away entire process VM, if address space not shared, 1028 * otherwise, create a new VM space so that other threads are 1029 * not disrupted 1030 */ 1031 map = &vmspace->vm_map; 1032 if (map_at_zero) 1033 sv_minuser = sv->sv_minuser; 1034 else 1035 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1036 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1037 vm_map_max(map) == sv->sv_maxuser) { 1038 shmexit(vmspace); 1039 pmap_remove_pages(vmspace_pmap(vmspace)); 1040 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1041 } else { 1042 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1043 if (error) 1044 return (error); 1045 vmspace = p->p_vmspace; 1046 map = &vmspace->vm_map; 1047 } 1048 1049 /* Map a shared page */ 1050 obj = sv->sv_shared_page_obj; 1051 if (obj != NULL) { 1052 vm_object_reference(obj); 1053 error = vm_map_fixed(map, obj, 0, 1054 sv->sv_shared_page_base, sv->sv_shared_page_len, 1055 VM_PROT_READ | VM_PROT_EXECUTE, VM_PROT_ALL, 1056 MAP_COPY_ON_WRITE | MAP_ACC_NO_CHARGE); 1057 if (error) { 1058 vm_object_deallocate(obj); 1059 return (error); 1060 } 1061 } 1062 1063 /* Allocate a new stack */ 1064 if (sv->sv_maxssiz != NULL) 1065 ssiz = *sv->sv_maxssiz; 1066 else 1067 ssiz = maxssiz; 1068 stack_addr = sv->sv_usrstack - ssiz; 1069 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1070 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1071 sv->sv_stackprot, 1072 VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1073 if (error) 1074 return (error); 1075 1076 #ifdef __ia64__ 1077 /* Allocate a new register stack */ 1078 stack_addr = IA64_BACKINGSTORE; 1079 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1080 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP); 1081 if (error) 1082 return (error); 1083 #endif 1084 1085 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 1086 * VM_STACK case, but they are still used to monitor the size of the 1087 * process stack so we can check the stack rlimit. 1088 */ 1089 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1090 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1091 1092 return (0); 1093 } 1094 1095 /* 1096 * Copy out argument and environment strings from the old process address 1097 * space into the temporary string buffer. 1098 */ 1099 int 1100 exec_copyin_args(struct image_args *args, char *fname, 1101 enum uio_seg segflg, char **argv, char **envv) 1102 { 1103 char *argp, *envp; 1104 int error; 1105 size_t length; 1106 1107 bzero(args, sizeof(*args)); 1108 if (argv == NULL) 1109 return (EFAULT); 1110 1111 /* 1112 * Allocate demand-paged memory for the file name, argument, and 1113 * environment strings. 1114 */ 1115 error = exec_alloc_args(args); 1116 if (error != 0) 1117 return (error); 1118 1119 /* 1120 * Copy the file name. 1121 */ 1122 if (fname != NULL) { 1123 args->fname = args->buf; 1124 error = (segflg == UIO_SYSSPACE) ? 1125 copystr(fname, args->fname, PATH_MAX, &length) : 1126 copyinstr(fname, args->fname, PATH_MAX, &length); 1127 if (error != 0) 1128 goto err_exit; 1129 } else 1130 length = 0; 1131 1132 args->begin_argv = args->buf + length; 1133 args->endp = args->begin_argv; 1134 args->stringspace = ARG_MAX; 1135 1136 /* 1137 * extract arguments first 1138 */ 1139 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 1140 if (argp == (caddr_t) -1) { 1141 error = EFAULT; 1142 goto err_exit; 1143 } 1144 if ((error = copyinstr(argp, args->endp, 1145 args->stringspace, &length))) { 1146 if (error == ENAMETOOLONG) 1147 error = E2BIG; 1148 goto err_exit; 1149 } 1150 args->stringspace -= length; 1151 args->endp += length; 1152 args->argc++; 1153 } 1154 1155 args->begin_envv = args->endp; 1156 1157 /* 1158 * extract environment strings 1159 */ 1160 if (envv) { 1161 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) { 1162 if (envp == (caddr_t)-1) { 1163 error = EFAULT; 1164 goto err_exit; 1165 } 1166 if ((error = copyinstr(envp, args->endp, 1167 args->stringspace, &length))) { 1168 if (error == ENAMETOOLONG) 1169 error = E2BIG; 1170 goto err_exit; 1171 } 1172 args->stringspace -= length; 1173 args->endp += length; 1174 args->envc++; 1175 } 1176 } 1177 1178 return (0); 1179 1180 err_exit: 1181 exec_free_args(args); 1182 return (error); 1183 } 1184 1185 /* 1186 * Allocate temporary demand-paged, zero-filled memory for the file name, 1187 * argument, and environment strings. Returns zero if the allocation succeeds 1188 * and ENOMEM otherwise. 1189 */ 1190 int 1191 exec_alloc_args(struct image_args *args) 1192 { 1193 1194 args->buf = (char *)kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 1195 return (args->buf != NULL ? 0 : ENOMEM); 1196 } 1197 1198 void 1199 exec_free_args(struct image_args *args) 1200 { 1201 1202 if (args->buf != NULL) { 1203 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf, 1204 PATH_MAX + ARG_MAX); 1205 args->buf = NULL; 1206 } 1207 if (args->fname_buf != NULL) { 1208 free(args->fname_buf, M_TEMP); 1209 args->fname_buf = NULL; 1210 } 1211 } 1212 1213 /* 1214 * Copy strings out to the new process address space, constructing new arg 1215 * and env vector tables. Return a pointer to the base so that it can be used 1216 * as the initial stack pointer. 1217 */ 1218 register_t * 1219 exec_copyout_strings(imgp) 1220 struct image_params *imgp; 1221 { 1222 int argc, envc; 1223 char **vectp; 1224 char *stringp, *destp; 1225 register_t *stack_base; 1226 struct ps_strings *arginfo; 1227 struct proc *p; 1228 size_t execpath_len; 1229 int szsigcode, szps; 1230 char canary[sizeof(long) * 8]; 1231 1232 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1233 /* 1234 * Calculate string base and vector table pointers. 1235 * Also deal with signal trampoline code for this exec type. 1236 */ 1237 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1238 execpath_len = strlen(imgp->execpath) + 1; 1239 else 1240 execpath_len = 0; 1241 p = imgp->proc; 1242 szsigcode = 0; 1243 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1244 if (p->p_sysent->sv_sigcode_base == 0) { 1245 if (p->p_sysent->sv_szsigcode != NULL) 1246 szsigcode = *(p->p_sysent->sv_szsigcode); 1247 } 1248 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 1249 roundup(execpath_len, sizeof(char *)) - 1250 roundup(sizeof(canary), sizeof(char *)) - 1251 roundup(szps, sizeof(char *)) - 1252 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *)); 1253 1254 /* 1255 * install sigcode 1256 */ 1257 if (szsigcode != 0) 1258 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo - 1259 szsigcode), szsigcode); 1260 1261 /* 1262 * Copy the image path for the rtld. 1263 */ 1264 if (execpath_len != 0) { 1265 imgp->execpathp = (uintptr_t)arginfo - szsigcode - execpath_len; 1266 copyout(imgp->execpath, (void *)imgp->execpathp, 1267 execpath_len); 1268 } 1269 1270 /* 1271 * Prepare the canary for SSP. 1272 */ 1273 arc4rand(canary, sizeof(canary), 0); 1274 imgp->canary = (uintptr_t)arginfo - szsigcode - execpath_len - 1275 sizeof(canary); 1276 copyout(canary, (void *)imgp->canary, sizeof(canary)); 1277 imgp->canarylen = sizeof(canary); 1278 1279 /* 1280 * Prepare the pagesizes array. 1281 */ 1282 imgp->pagesizes = (uintptr_t)arginfo - szsigcode - execpath_len - 1283 roundup(sizeof(canary), sizeof(char *)) - szps; 1284 copyout(pagesizes, (void *)imgp->pagesizes, szps); 1285 imgp->pagesizeslen = szps; 1286 1287 /* 1288 * If we have a valid auxargs ptr, prepare some room 1289 * on the stack. 1290 */ 1291 if (imgp->auxargs) { 1292 /* 1293 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1294 * lower compatibility. 1295 */ 1296 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1297 (AT_COUNT * 2); 1298 /* 1299 * The '+ 2' is for the null pointers at the end of each of 1300 * the arg and env vector sets,and imgp->auxarg_size is room 1301 * for argument of Runtime loader. 1302 */ 1303 vectp = (char **)(destp - (imgp->args->argc + 1304 imgp->args->envc + 2 + imgp->auxarg_size) 1305 * sizeof(char *)); 1306 } else { 1307 /* 1308 * The '+ 2' is for the null pointers at the end of each of 1309 * the arg and env vector sets 1310 */ 1311 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) * 1312 sizeof(char *)); 1313 } 1314 1315 /* 1316 * vectp also becomes our initial stack base 1317 */ 1318 stack_base = (register_t *)vectp; 1319 1320 stringp = imgp->args->begin_argv; 1321 argc = imgp->args->argc; 1322 envc = imgp->args->envc; 1323 1324 /* 1325 * Copy out strings - arguments and environment. 1326 */ 1327 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace); 1328 1329 /* 1330 * Fill in "ps_strings" struct for ps, w, etc. 1331 */ 1332 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1333 suword32(&arginfo->ps_nargvstr, argc); 1334 1335 /* 1336 * Fill in argument portion of vector table. 1337 */ 1338 for (; argc > 0; --argc) { 1339 suword(vectp++, (long)(intptr_t)destp); 1340 while (*stringp++ != 0) 1341 destp++; 1342 destp++; 1343 } 1344 1345 /* a null vector table pointer separates the argp's from the envp's */ 1346 suword(vectp++, 0); 1347 1348 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1349 suword32(&arginfo->ps_nenvstr, envc); 1350 1351 /* 1352 * Fill in environment portion of vector table. 1353 */ 1354 for (; envc > 0; --envc) { 1355 suword(vectp++, (long)(intptr_t)destp); 1356 while (*stringp++ != 0) 1357 destp++; 1358 destp++; 1359 } 1360 1361 /* end of vector table is a null pointer */ 1362 suword(vectp, 0); 1363 1364 return (stack_base); 1365 } 1366 1367 /* 1368 * Check permissions of file to execute. 1369 * Called with imgp->vp locked. 1370 * Return 0 for success or error code on failure. 1371 */ 1372 int 1373 exec_check_permissions(imgp) 1374 struct image_params *imgp; 1375 { 1376 struct vnode *vp = imgp->vp; 1377 struct vattr *attr = imgp->attr; 1378 struct thread *td; 1379 int error, writecount; 1380 1381 td = curthread; 1382 1383 /* Get file attributes */ 1384 error = VOP_GETATTR(vp, attr, td->td_ucred); 1385 if (error) 1386 return (error); 1387 1388 #ifdef MAC 1389 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1390 if (error) 1391 return (error); 1392 #endif 1393 1394 /* 1395 * 1) Check if file execution is disabled for the filesystem that 1396 * this file resides on. 1397 * 2) Ensure that at least one execute bit is on. Otherwise, a 1398 * privileged user will always succeed, and we don't want this 1399 * to happen unless the file really is executable. 1400 * 3) Ensure that the file is a regular file. 1401 */ 1402 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1403 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1404 (attr->va_type != VREG)) 1405 return (EACCES); 1406 1407 /* 1408 * Zero length files can't be exec'd 1409 */ 1410 if (attr->va_size == 0) 1411 return (ENOEXEC); 1412 1413 /* 1414 * Check for execute permission to file based on current credentials. 1415 */ 1416 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1417 if (error) 1418 return (error); 1419 1420 /* 1421 * Check number of open-for-writes on the file and deny execution 1422 * if there are any. 1423 */ 1424 error = VOP_GET_WRITECOUNT(vp, &writecount); 1425 if (error != 0) 1426 return (error); 1427 if (writecount != 0) 1428 return (ETXTBSY); 1429 1430 /* 1431 * Call filesystem specific open routine (which does nothing in the 1432 * general case). 1433 */ 1434 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1435 if (error == 0) 1436 imgp->opened = 1; 1437 return (error); 1438 } 1439 1440 /* 1441 * Exec handler registration 1442 */ 1443 int 1444 exec_register(execsw_arg) 1445 const struct execsw *execsw_arg; 1446 { 1447 const struct execsw **es, **xs, **newexecsw; 1448 int count = 2; /* New slot and trailing NULL */ 1449 1450 if (execsw) 1451 for (es = execsw; *es; es++) 1452 count++; 1453 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1454 if (newexecsw == NULL) 1455 return (ENOMEM); 1456 xs = newexecsw; 1457 if (execsw) 1458 for (es = execsw; *es; es++) 1459 *xs++ = *es; 1460 *xs++ = execsw_arg; 1461 *xs = NULL; 1462 if (execsw) 1463 free(execsw, M_TEMP); 1464 execsw = newexecsw; 1465 return (0); 1466 } 1467 1468 int 1469 exec_unregister(execsw_arg) 1470 const struct execsw *execsw_arg; 1471 { 1472 const struct execsw **es, **xs, **newexecsw; 1473 int count = 1; 1474 1475 if (execsw == NULL) 1476 panic("unregister with no handlers left?\n"); 1477 1478 for (es = execsw; *es; es++) { 1479 if (*es == execsw_arg) 1480 break; 1481 } 1482 if (*es == NULL) 1483 return (ENOENT); 1484 for (es = execsw; *es; es++) 1485 if (*es != execsw_arg) 1486 count++; 1487 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1488 if (newexecsw == NULL) 1489 return (ENOMEM); 1490 xs = newexecsw; 1491 for (es = execsw; *es; es++) 1492 if (*es != execsw_arg) 1493 *xs++ = *es; 1494 *xs = NULL; 1495 if (execsw) 1496 free(execsw, M_TEMP); 1497 execsw = newexecsw; 1498 return (0); 1499 } 1500