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_ktrace.h" 33 #include "opt_vm.h" 34 35 #include <sys/param.h> 36 #include <sys/capsicum.h> 37 #include <sys/systm.h> 38 #include <sys/eventhandler.h> 39 #include <sys/lock.h> 40 #include <sys/mutex.h> 41 #include <sys/sysproto.h> 42 #include <sys/signalvar.h> 43 #include <sys/kernel.h> 44 #include <sys/mount.h> 45 #include <sys/filedesc.h> 46 #include <sys/fcntl.h> 47 #include <sys/acct.h> 48 #include <sys/exec.h> 49 #include <sys/imgact.h> 50 #include <sys/imgact_elf.h> 51 #include <sys/wait.h> 52 #include <sys/malloc.h> 53 #include <sys/priv.h> 54 #include <sys/proc.h> 55 #include <sys/pioctl.h> 56 #include <sys/namei.h> 57 #include <sys/resourcevar.h> 58 #include <sys/rwlock.h> 59 #include <sys/sched.h> 60 #include <sys/sdt.h> 61 #include <sys/sf_buf.h> 62 #include <sys/syscallsubr.h> 63 #include <sys/sysent.h> 64 #include <sys/shm.h> 65 #include <sys/sysctl.h> 66 #include <sys/vnode.h> 67 #include <sys/stat.h> 68 #ifdef KTRACE 69 #include <sys/ktrace.h> 70 #endif 71 72 #include <vm/vm.h> 73 #include <vm/vm_param.h> 74 #include <vm/pmap.h> 75 #include <vm/vm_page.h> 76 #include <vm/vm_map.h> 77 #include <vm/vm_kern.h> 78 #include <vm/vm_extern.h> 79 #include <vm/vm_object.h> 80 #include <vm/vm_pager.h> 81 82 #ifdef HWPMC_HOOKS 83 #include <sys/pmckern.h> 84 #endif 85 86 #include <machine/reg.h> 87 88 #include <security/audit/audit.h> 89 #include <security/mac/mac_framework.h> 90 91 #ifdef KDTRACE_HOOKS 92 #include <sys/dtrace_bsd.h> 93 dtrace_execexit_func_t dtrace_fasttrap_exec; 94 #endif 95 96 SDT_PROVIDER_DECLARE(proc); 97 SDT_PROBE_DEFINE1(proc, kernel, , exec, "char *"); 98 SDT_PROBE_DEFINE1(proc, kernel, , exec__failure, "int"); 99 SDT_PROBE_DEFINE1(proc, kernel, , exec__success, "char *"); 100 101 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 102 103 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 104 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 105 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 106 static int do_execve(struct thread *td, struct image_args *args, 107 struct mac *mac_p); 108 109 /* XXX This should be vm_size_t. */ 110 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD, 111 NULL, 0, sysctl_kern_ps_strings, "LU", ""); 112 113 /* XXX This should be vm_size_t. */ 114 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 115 CTLFLAG_CAPRD, NULL, 0, sysctl_kern_usrstack, "LU", ""); 116 117 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 118 NULL, 0, sysctl_kern_stackprot, "I", ""); 119 120 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 121 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 122 &ps_arg_cache_limit, 0, ""); 123 124 static int disallow_high_osrel; 125 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW, 126 &disallow_high_osrel, 0, 127 "Disallow execution of binaries built for higher version of the world"); 128 129 static int map_at_zero = 0; 130 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RWTUN, &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 struct vmspace *oldvmspace; 284 int error; 285 286 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 287 args->begin_envv - args->begin_argv); 288 AUDIT_ARG_ENVV(args->begin_envv, args->envc, 289 args->endp - args->begin_envv); 290 if (p->p_flag & P_HADTHREADS) { 291 PROC_LOCK(p); 292 if (thread_single(SINGLE_BOUNDARY)) { 293 PROC_UNLOCK(p); 294 exec_free_args(args); 295 return (ERESTART); /* Try again later. */ 296 } 297 PROC_UNLOCK(p); 298 } 299 300 KASSERT((td->td_pflags & TDP_EXECVMSPC) == 0, ("nested execve")); 301 oldvmspace = td->td_proc->p_vmspace; 302 error = do_execve(td, args, mac_p); 303 304 if (p->p_flag & P_HADTHREADS) { 305 PROC_LOCK(p); 306 /* 307 * If success, we upgrade to SINGLE_EXIT state to 308 * force other threads to suicide. 309 */ 310 if (error == 0) 311 thread_single(SINGLE_EXIT); 312 else 313 thread_single_end(); 314 PROC_UNLOCK(p); 315 } 316 if ((td->td_pflags & TDP_EXECVMSPC) != 0) { 317 KASSERT(td->td_proc->p_vmspace != oldvmspace, 318 ("oldvmspace still used")); 319 vmspace_free(oldvmspace); 320 td->td_pflags &= ~TDP_EXECVMSPC; 321 } 322 323 return (error); 324 } 325 326 /* 327 * In-kernel implementation of execve(). All arguments are assumed to be 328 * userspace pointers from the passed thread. 329 */ 330 static int 331 do_execve(td, args, mac_p) 332 struct thread *td; 333 struct image_args *args; 334 struct mac *mac_p; 335 { 336 struct proc *p = td->td_proc; 337 struct nameidata nd; 338 struct ucred *newcred = NULL, *oldcred; 339 struct uidinfo *euip = NULL; 340 register_t *stack_base; 341 int error, i; 342 struct image_params image_params, *imgp; 343 struct vattr attr; 344 int (*img_first)(struct image_params *); 345 struct pargs *oldargs = NULL, *newargs = NULL; 346 struct sigacts *oldsigacts, *newsigacts; 347 #ifdef KTRACE 348 struct vnode *tracevp = NULL; 349 struct ucred *tracecred = NULL; 350 #endif 351 struct vnode *textvp = NULL, *binvp; 352 cap_rights_t rights; 353 int credential_changing; 354 int textset; 355 #ifdef MAC 356 struct label *interpvplabel = NULL; 357 int will_transition; 358 #endif 359 #ifdef HWPMC_HOOKS 360 struct pmckern_procexec pe; 361 #endif 362 static const char fexecv_proc_title[] = "(fexecv)"; 363 364 imgp = &image_params; 365 366 /* 367 * Lock the process and set the P_INEXEC flag to indicate that 368 * it should be left alone until we're done here. This is 369 * necessary to avoid race conditions - e.g. in ptrace() - 370 * that might allow a local user to illicitly obtain elevated 371 * privileges. 372 */ 373 PROC_LOCK(p); 374 KASSERT((p->p_flag & P_INEXEC) == 0, 375 ("%s(): process already has P_INEXEC flag", __func__)); 376 p->p_flag |= P_INEXEC; 377 PROC_UNLOCK(p); 378 379 /* 380 * Initialize part of the common data 381 */ 382 bzero(imgp, sizeof(*imgp)); 383 imgp->proc = p; 384 imgp->attr = &attr; 385 imgp->args = args; 386 387 #ifdef MAC 388 error = mac_execve_enter(imgp, mac_p); 389 if (error) 390 goto exec_fail; 391 #endif 392 393 /* 394 * Translate the file name. namei() returns a vnode pointer 395 * in ni_vp amoung other things. 396 * 397 * XXXAUDIT: It would be desirable to also audit the name of the 398 * interpreter if this is an interpreted binary. 399 */ 400 if (args->fname != NULL) { 401 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 402 | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 403 } 404 405 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 406 407 interpret: 408 if (args->fname != NULL) { 409 #ifdef CAPABILITY_MODE 410 /* 411 * While capability mode can't reach this point via direct 412 * path arguments to execve(), we also don't allow 413 * interpreters to be used in capability mode (for now). 414 * Catch indirect lookups and return a permissions error. 415 */ 416 if (IN_CAPABILITY_MODE(td)) { 417 error = ECAPMODE; 418 goto exec_fail; 419 } 420 #endif 421 error = namei(&nd); 422 if (error) 423 goto exec_fail; 424 425 binvp = nd.ni_vp; 426 imgp->vp = binvp; 427 } else { 428 AUDIT_ARG_FD(args->fd); 429 /* 430 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 431 */ 432 error = fgetvp_exec(td, args->fd, 433 cap_rights_init(&rights, CAP_FEXECVE), &binvp); 434 if (error) 435 goto exec_fail; 436 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY); 437 AUDIT_ARG_VNODE1(binvp); 438 imgp->vp = binvp; 439 } 440 441 /* 442 * Check file permissions (also 'opens' file) 443 */ 444 error = exec_check_permissions(imgp); 445 if (error) 446 goto exec_fail_dealloc; 447 448 imgp->object = imgp->vp->v_object; 449 if (imgp->object != NULL) 450 vm_object_reference(imgp->object); 451 452 /* 453 * Set VV_TEXT now so no one can write to the executable while we're 454 * activating it. 455 * 456 * Remember if this was set before and unset it in case this is not 457 * actually an executable image. 458 */ 459 textset = VOP_IS_TEXT(imgp->vp); 460 VOP_SET_TEXT(imgp->vp); 461 462 error = exec_map_first_page(imgp); 463 if (error) 464 goto exec_fail_dealloc; 465 466 imgp->proc->p_osrel = 0; 467 /* 468 * If the current process has a special image activator it 469 * wants to try first, call it. For example, emulating shell 470 * scripts differently. 471 */ 472 error = -1; 473 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 474 error = img_first(imgp); 475 476 /* 477 * Loop through the list of image activators, calling each one. 478 * An activator returns -1 if there is no match, 0 on success, 479 * and an error otherwise. 480 */ 481 for (i = 0; error == -1 && execsw[i]; ++i) { 482 if (execsw[i]->ex_imgact == NULL || 483 execsw[i]->ex_imgact == img_first) { 484 continue; 485 } 486 error = (*execsw[i]->ex_imgact)(imgp); 487 } 488 489 if (error) { 490 if (error == -1) { 491 if (textset == 0) 492 VOP_UNSET_TEXT(imgp->vp); 493 error = ENOEXEC; 494 } 495 goto exec_fail_dealloc; 496 } 497 498 /* 499 * Special interpreter operation, cleanup and loop up to try to 500 * activate the interpreter. 501 */ 502 if (imgp->interpreted) { 503 exec_unmap_first_page(imgp); 504 /* 505 * VV_TEXT needs to be unset for scripts. There is a short 506 * period before we determine that something is a script where 507 * VV_TEXT will be set. The vnode lock is held over this 508 * entire period so nothing should illegitimately be blocked. 509 */ 510 VOP_UNSET_TEXT(imgp->vp); 511 /* free name buffer and old vnode */ 512 if (args->fname != NULL) 513 NDFREE(&nd, NDF_ONLY_PNBUF); 514 #ifdef MAC 515 mac_execve_interpreter_enter(binvp, &interpvplabel); 516 #endif 517 if (imgp->opened) { 518 VOP_CLOSE(binvp, FREAD, td->td_ucred, td); 519 imgp->opened = 0; 520 } 521 vput(binvp); 522 vm_object_deallocate(imgp->object); 523 imgp->object = NULL; 524 /* set new name to that of the interpreter */ 525 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 526 UIO_SYSSPACE, imgp->interpreter_name, td); 527 args->fname = imgp->interpreter_name; 528 goto interpret; 529 } 530 531 /* 532 * NB: We unlock the vnode here because it is believed that none 533 * of the sv_copyout_strings/sv_fixup operations require the vnode. 534 */ 535 VOP_UNLOCK(imgp->vp, 0); 536 537 /* 538 * Do the best to calculate the full path to the image file. 539 */ 540 if (imgp->auxargs != NULL && 541 ((args->fname != NULL && args->fname[0] == '/') || 542 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0)) 543 imgp->execpath = args->fname; 544 545 if (disallow_high_osrel && 546 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 547 error = ENOEXEC; 548 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 549 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 550 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 551 goto exec_fail_dealloc; 552 } 553 554 /* 555 * Copy out strings (args and env) and initialize stack base 556 */ 557 if (p->p_sysent->sv_copyout_strings) 558 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 559 else 560 stack_base = exec_copyout_strings(imgp); 561 562 /* 563 * If custom stack fixup routine present for this process 564 * let it do the stack setup. 565 * Else stuff argument count as first item on stack 566 */ 567 if (p->p_sysent->sv_fixup != NULL) 568 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 569 else 570 suword(--stack_base, imgp->args->argc); 571 572 /* 573 * For security and other reasons, the file descriptor table cannot 574 * be shared after an exec. 575 */ 576 fdunshare(td); 577 /* close files on exec */ 578 fdcloseexec(td); 579 580 /* 581 * Malloc things before we need locks. 582 */ 583 i = imgp->args->begin_envv - imgp->args->begin_argv; 584 /* Cache arguments if they fit inside our allowance */ 585 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 586 newargs = pargs_alloc(i); 587 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 588 } 589 590 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 591 592 /* Get a reference to the vnode prior to locking the proc */ 593 VREF(binvp); 594 595 /* 596 * For security and other reasons, signal handlers cannot 597 * be shared after an exec. The new process gets a copy of the old 598 * handlers. In execsigs(), the new process will have its signals 599 * reset. 600 */ 601 if (sigacts_shared(p->p_sigacts)) { 602 oldsigacts = p->p_sigacts; 603 newsigacts = sigacts_alloc(); 604 sigacts_copy(newsigacts, oldsigacts); 605 } else { 606 oldsigacts = NULL; 607 newsigacts = NULL; /* satisfy gcc */ 608 } 609 610 PROC_LOCK(p); 611 if (oldsigacts) 612 p->p_sigacts = newsigacts; 613 oldcred = p->p_ucred; 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_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 * Both fdsetugidsafety() and fdcheckstd() may call functions 692 * taking sleepable locks, so temporarily drop our locks. 693 */ 694 PROC_UNLOCK(p); 695 VOP_UNLOCK(imgp->vp, 0); 696 fdsetugidsafety(td); 697 error = fdcheckstd(td); 698 if (error != 0) 699 goto done1; 700 newcred = crdup(oldcred); 701 euip = uifind(attr.va_uid); 702 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 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 } else { 728 if (oldcred->cr_uid == oldcred->cr_ruid && 729 oldcred->cr_gid == oldcred->cr_rgid) 730 p->p_flag &= ~P_SUGID; 731 /* 732 * Implement correct POSIX saved-id behavior. 733 * 734 * XXX: It's not clear that the existing behavior is 735 * POSIX-compliant. A number of sources indicate that the 736 * saved uid/gid should only be updated if the new ruid is 737 * not equal to the old ruid, or the new euid is not equal 738 * to the old euid and the new euid is not equal to the old 739 * ruid. The FreeBSD code always updates the saved uid/gid. 740 * Also, this code uses the new (replaced) euid and egid as 741 * the source, which may or may not be the right ones to use. 742 */ 743 if (oldcred->cr_svuid != oldcred->cr_uid || 744 oldcred->cr_svgid != oldcred->cr_gid) { 745 PROC_UNLOCK(p); 746 VOP_UNLOCK(imgp->vp, 0); 747 newcred = crdup(oldcred); 748 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 749 PROC_LOCK(p); 750 change_svuid(newcred, newcred->cr_uid); 751 change_svgid(newcred, newcred->cr_gid); 752 p->p_ucred = newcred; 753 } 754 } 755 756 /* 757 * Store the vp for use in procfs. This vnode was referenced prior 758 * to locking the proc lock. 759 */ 760 textvp = p->p_textvp; 761 p->p_textvp = binvp; 762 763 #ifdef KDTRACE_HOOKS 764 /* 765 * Tell the DTrace fasttrap provider about the exec if it 766 * has declared an interest. 767 */ 768 if (dtrace_fasttrap_exec) 769 dtrace_fasttrap_exec(p); 770 #endif 771 772 /* 773 * Notify others that we exec'd, and clear the P_INEXEC flag 774 * as we're now a bona fide freshly-execed process. 775 */ 776 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 777 p->p_flag &= ~P_INEXEC; 778 779 /* clear "fork but no exec" flag, as we _are_ execing */ 780 p->p_acflag &= ~AFORK; 781 782 /* 783 * Free any previous argument cache and replace it with 784 * the new argument cache, if any. 785 */ 786 oldargs = p->p_args; 787 p->p_args = newargs; 788 newargs = NULL; 789 790 #ifdef HWPMC_HOOKS 791 /* 792 * Check if system-wide sampling is in effect or if the 793 * current process is using PMCs. If so, do exec() time 794 * processing. This processing needs to happen AFTER the 795 * P_INEXEC flag is cleared. 796 * 797 * The proc lock needs to be released before taking the PMC 798 * SX. 799 */ 800 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 801 PROC_UNLOCK(p); 802 VOP_UNLOCK(imgp->vp, 0); 803 pe.pm_credentialschanged = credential_changing; 804 pe.pm_entryaddr = imgp->entry_addr; 805 806 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 807 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 808 } else 809 PROC_UNLOCK(p); 810 #else /* !HWPMC_HOOKS */ 811 PROC_UNLOCK(p); 812 #endif 813 814 /* Set values passed into the program in registers. */ 815 if (p->p_sysent->sv_setregs) 816 (*p->p_sysent->sv_setregs)(td, imgp, 817 (u_long)(uintptr_t)stack_base); 818 else 819 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 820 821 vfs_mark_atime(imgp->vp, td->td_ucred); 822 823 SDT_PROBE(proc, kernel, , exec__success, args->fname, 0, 0, 0, 0); 824 825 VOP_UNLOCK(imgp->vp, 0); 826 done1: 827 /* 828 * Free any resources malloc'd earlier that we didn't use. 829 */ 830 if (euip != NULL) 831 uifree(euip); 832 if (newcred != NULL) 833 crfree(oldcred); 834 835 /* 836 * Handle deferred decrement of ref counts. 837 */ 838 if (textvp != NULL) 839 vrele(textvp); 840 if (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_activate(ma[0]); 974 vm_page_unlock(ma[0]); 975 VM_OBJECT_WUNLOCK(object); 976 977 imgp->firstpage = sf_buf_alloc(ma[0], 0); 978 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 979 980 return (0); 981 } 982 983 void 984 exec_unmap_first_page(imgp) 985 struct image_params *imgp; 986 { 987 vm_page_t m; 988 989 if (imgp->firstpage != NULL) { 990 m = sf_buf_page(imgp->firstpage); 991 sf_buf_free(imgp->firstpage); 992 imgp->firstpage = NULL; 993 vm_page_lock(m); 994 vm_page_unhold(m); 995 vm_page_unlock(m); 996 } 997 } 998 999 /* 1000 * Destroy old address space, and allocate a new stack 1001 * The new stack is only SGROWSIZ large because it is grown 1002 * automatically in trap.c. 1003 */ 1004 int 1005 exec_new_vmspace(imgp, sv) 1006 struct image_params *imgp; 1007 struct sysentvec *sv; 1008 { 1009 int error; 1010 struct proc *p = imgp->proc; 1011 struct vmspace *vmspace = p->p_vmspace; 1012 vm_object_t obj; 1013 vm_offset_t sv_minuser, stack_addr; 1014 vm_map_t map; 1015 u_long ssiz; 1016 1017 imgp->vmspace_destroyed = 1; 1018 imgp->sysent = sv; 1019 1020 /* May be called with Giant held */ 1021 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1022 1023 /* 1024 * Blow away entire process VM, if address space not shared, 1025 * otherwise, create a new VM space so that other threads are 1026 * not disrupted 1027 */ 1028 map = &vmspace->vm_map; 1029 if (map_at_zero) 1030 sv_minuser = sv->sv_minuser; 1031 else 1032 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1033 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1034 vm_map_max(map) == sv->sv_maxuser) { 1035 shmexit(vmspace); 1036 pmap_remove_pages(vmspace_pmap(vmspace)); 1037 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1038 } else { 1039 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1040 if (error) 1041 return (error); 1042 vmspace = p->p_vmspace; 1043 map = &vmspace->vm_map; 1044 } 1045 1046 /* Map a shared page */ 1047 obj = sv->sv_shared_page_obj; 1048 if (obj != NULL) { 1049 vm_object_reference(obj); 1050 error = vm_map_fixed(map, obj, 0, 1051 sv->sv_shared_page_base, sv->sv_shared_page_len, 1052 VM_PROT_READ | VM_PROT_EXECUTE, 1053 VM_PROT_READ | VM_PROT_EXECUTE, 1054 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1055 if (error) { 1056 vm_object_deallocate(obj); 1057 return (error); 1058 } 1059 } 1060 1061 /* Allocate a new stack */ 1062 if (sv->sv_maxssiz != NULL) 1063 ssiz = *sv->sv_maxssiz; 1064 else 1065 ssiz = maxssiz; 1066 stack_addr = sv->sv_usrstack - ssiz; 1067 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1068 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1069 sv->sv_stackprot, 1070 VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1071 if (error) 1072 return (error); 1073 1074 /* 1075 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they 1076 * are still used to enforce the stack rlimit on the process stack. 1077 */ 1078 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1079 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1080 1081 return (0); 1082 } 1083 1084 /* 1085 * Copy out argument and environment strings from the old process address 1086 * space into the temporary string buffer. 1087 */ 1088 int 1089 exec_copyin_args(struct image_args *args, char *fname, 1090 enum uio_seg segflg, char **argv, char **envv) 1091 { 1092 u_long argp, envp; 1093 int error; 1094 size_t length; 1095 1096 bzero(args, sizeof(*args)); 1097 if (argv == NULL) 1098 return (EFAULT); 1099 1100 /* 1101 * Allocate demand-paged memory for the file name, argument, and 1102 * environment strings. 1103 */ 1104 error = exec_alloc_args(args); 1105 if (error != 0) 1106 return (error); 1107 1108 /* 1109 * Copy the file name. 1110 */ 1111 if (fname != NULL) { 1112 args->fname = args->buf; 1113 error = (segflg == UIO_SYSSPACE) ? 1114 copystr(fname, args->fname, PATH_MAX, &length) : 1115 copyinstr(fname, args->fname, PATH_MAX, &length); 1116 if (error != 0) 1117 goto err_exit; 1118 } else 1119 length = 0; 1120 1121 args->begin_argv = args->buf + length; 1122 args->endp = args->begin_argv; 1123 args->stringspace = ARG_MAX; 1124 1125 /* 1126 * extract arguments first 1127 */ 1128 for (;;) { 1129 error = fueword(argv++, &argp); 1130 if (error == -1) { 1131 error = EFAULT; 1132 goto err_exit; 1133 } 1134 if (argp == 0) 1135 break; 1136 error = copyinstr((void *)(uintptr_t)argp, args->endp, 1137 args->stringspace, &length); 1138 if (error != 0) { 1139 if (error == ENAMETOOLONG) 1140 error = E2BIG; 1141 goto err_exit; 1142 } 1143 args->stringspace -= length; 1144 args->endp += length; 1145 args->argc++; 1146 } 1147 1148 args->begin_envv = args->endp; 1149 1150 /* 1151 * extract environment strings 1152 */ 1153 if (envv) { 1154 for (;;) { 1155 error = fueword(envv++, &envp); 1156 if (error == -1) { 1157 error = EFAULT; 1158 goto err_exit; 1159 } 1160 if (envp == 0) 1161 break; 1162 error = copyinstr((void *)(uintptr_t)envp, 1163 args->endp, args->stringspace, &length); 1164 if (error != 0) { 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; 1222 uintptr_t destp; 1223 register_t *stack_base; 1224 struct ps_strings *arginfo; 1225 struct proc *p; 1226 size_t execpath_len; 1227 int szsigcode, szps; 1228 char canary[sizeof(long) * 8]; 1229 1230 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1231 /* 1232 * Calculate string base and vector table pointers. 1233 * Also deal with signal trampoline code for this exec type. 1234 */ 1235 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1236 execpath_len = strlen(imgp->execpath) + 1; 1237 else 1238 execpath_len = 0; 1239 p = imgp->proc; 1240 szsigcode = 0; 1241 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1242 if (p->p_sysent->sv_sigcode_base == 0) { 1243 if (p->p_sysent->sv_szsigcode != NULL) 1244 szsigcode = *(p->p_sysent->sv_szsigcode); 1245 } 1246 destp = (uintptr_t)arginfo; 1247 1248 /* 1249 * install sigcode 1250 */ 1251 if (szsigcode != 0) { 1252 destp -= szsigcode; 1253 destp = rounddown2(destp, sizeof(void *)); 1254 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode); 1255 } 1256 1257 /* 1258 * Copy the image path for the rtld. 1259 */ 1260 if (execpath_len != 0) { 1261 destp -= execpath_len; 1262 imgp->execpathp = destp; 1263 copyout(imgp->execpath, (void *)destp, execpath_len); 1264 } 1265 1266 /* 1267 * Prepare the canary for SSP. 1268 */ 1269 arc4rand(canary, sizeof(canary), 0); 1270 destp -= sizeof(canary); 1271 imgp->canary = destp; 1272 copyout(canary, (void *)destp, sizeof(canary)); 1273 imgp->canarylen = sizeof(canary); 1274 1275 /* 1276 * Prepare the pagesizes array. 1277 */ 1278 destp -= szps; 1279 destp = rounddown2(destp, sizeof(void *)); 1280 imgp->pagesizes = destp; 1281 copyout(pagesizes, (void *)destp, szps); 1282 imgp->pagesizeslen = szps; 1283 1284 destp -= ARG_MAX - imgp->args->stringspace; 1285 destp = rounddown2(destp, sizeof(void *)); 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 1312 + 2) * 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, (void *)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