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