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/capability.h> 37 #include <sys/systm.h> 38 #include <sys/capability.h> 39 #include <sys/eventhandler.h> 40 #include <sys/lock.h> 41 #include <sys/mutex.h> 42 #include <sys/sysproto.h> 43 #include <sys/signalvar.h> 44 #include <sys/kernel.h> 45 #include <sys/mount.h> 46 #include <sys/filedesc.h> 47 #include <sys/fcntl.h> 48 #include <sys/acct.h> 49 #include <sys/exec.h> 50 #include <sys/imgact.h> 51 #include <sys/imgact_elf.h> 52 #include <sys/wait.h> 53 #include <sys/malloc.h> 54 #include <sys/priv.h> 55 #include <sys/proc.h> 56 #include <sys/pioctl.h> 57 #include <sys/namei.h> 58 #include <sys/resourcevar.h> 59 #include <sys/rwlock.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_DEFINE1(proc, kernel, , exec, "char *"); 99 SDT_PROBE_DEFINE1(proc, kernel, , exec__failure, "int"); 100 SDT_PROBE_DEFINE1(proc, kernel, , exec__success, "char *"); 101 102 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 103 104 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 105 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 106 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 107 static int do_execve(struct thread *td, struct image_args *args, 108 struct mac *mac_p); 109 110 /* XXX This should be vm_size_t. */ 111 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD, 112 NULL, 0, sysctl_kern_ps_strings, "LU", ""); 113 114 /* XXX This should be vm_size_t. */ 115 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 116 CTLFLAG_CAPRD, NULL, 0, sysctl_kern_usrstack, "LU", ""); 117 118 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 119 NULL, 0, sysctl_kern_stackprot, "I", ""); 120 121 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 122 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 123 &ps_arg_cache_limit, 0, ""); 124 125 static int disallow_high_osrel; 126 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW, 127 &disallow_high_osrel, 0, 128 "Disallow execution of binaries built for higher version of the world"); 129 130 static int map_at_zero = 0; 131 TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero); 132 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &map_at_zero, 0, 133 "Permit processes to map an object at virtual address 0."); 134 135 static int 136 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 137 { 138 struct proc *p; 139 int error; 140 141 p = curproc; 142 #ifdef SCTL_MASK32 143 if (req->flags & SCTL_MASK32) { 144 unsigned int val; 145 val = (unsigned int)p->p_sysent->sv_psstrings; 146 error = SYSCTL_OUT(req, &val, sizeof(val)); 147 } else 148 #endif 149 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 150 sizeof(p->p_sysent->sv_psstrings)); 151 return error; 152 } 153 154 static int 155 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 156 { 157 struct proc *p; 158 int error; 159 160 p = curproc; 161 #ifdef SCTL_MASK32 162 if (req->flags & SCTL_MASK32) { 163 unsigned int val; 164 val = (unsigned int)p->p_sysent->sv_usrstack; 165 error = SYSCTL_OUT(req, &val, sizeof(val)); 166 } else 167 #endif 168 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 169 sizeof(p->p_sysent->sv_usrstack)); 170 return error; 171 } 172 173 static int 174 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 175 { 176 struct proc *p; 177 178 p = curproc; 179 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 180 sizeof(p->p_sysent->sv_stackprot))); 181 } 182 183 /* 184 * Each of the items is a pointer to a `const struct execsw', hence the 185 * double pointer here. 186 */ 187 static const struct execsw **execsw; 188 189 #ifndef _SYS_SYSPROTO_H_ 190 struct execve_args { 191 char *fname; 192 char **argv; 193 char **envv; 194 }; 195 #endif 196 197 int 198 sys_execve(td, uap) 199 struct thread *td; 200 struct execve_args /* { 201 char *fname; 202 char **argv; 203 char **envv; 204 } */ *uap; 205 { 206 int error; 207 struct image_args args; 208 209 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 210 uap->argv, uap->envv); 211 if (error == 0) 212 error = kern_execve(td, &args, NULL); 213 return (error); 214 } 215 216 #ifndef _SYS_SYSPROTO_H_ 217 struct fexecve_args { 218 int fd; 219 char **argv; 220 char **envv; 221 } 222 #endif 223 int 224 sys_fexecve(struct thread *td, struct fexecve_args *uap) 225 { 226 int error; 227 struct image_args args; 228 229 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 230 uap->argv, uap->envv); 231 if (error == 0) { 232 args.fd = uap->fd; 233 error = kern_execve(td, &args, NULL); 234 } 235 return (error); 236 } 237 238 #ifndef _SYS_SYSPROTO_H_ 239 struct __mac_execve_args { 240 char *fname; 241 char **argv; 242 char **envv; 243 struct mac *mac_p; 244 }; 245 #endif 246 247 int 248 sys___mac_execve(td, uap) 249 struct thread *td; 250 struct __mac_execve_args /* { 251 char *fname; 252 char **argv; 253 char **envv; 254 struct mac *mac_p; 255 } */ *uap; 256 { 257 #ifdef MAC 258 int error; 259 struct image_args args; 260 261 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 262 uap->argv, uap->envv); 263 if (error == 0) 264 error = kern_execve(td, &args, uap->mac_p); 265 return (error); 266 #else 267 return (ENOSYS); 268 #endif 269 } 270 271 /* 272 * XXX: kern_execve has the astonishing property of not always returning to 273 * the caller. If sufficiently bad things happen during the call to 274 * do_execve(), it can end up calling exit1(); as a result, callers must 275 * avoid doing anything which they might need to undo (e.g., allocating 276 * memory). 277 */ 278 int 279 kern_execve(td, args, mac_p) 280 struct thread *td; 281 struct image_args *args; 282 struct mac *mac_p; 283 { 284 struct proc *p = td->td_proc; 285 int error; 286 287 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 288 args->begin_envv - args->begin_argv); 289 AUDIT_ARG_ENVV(args->begin_envv, args->envc, 290 args->endp - args->begin_envv); 291 if (p->p_flag & P_HADTHREADS) { 292 PROC_LOCK(p); 293 if (thread_single(SINGLE_BOUNDARY)) { 294 PROC_UNLOCK(p); 295 exec_free_args(args); 296 return (ERESTART); /* Try again later. */ 297 } 298 PROC_UNLOCK(p); 299 } 300 301 error = do_execve(td, args, mac_p); 302 303 if (p->p_flag & P_HADTHREADS) { 304 PROC_LOCK(p); 305 /* 306 * If success, we upgrade to SINGLE_EXIT state to 307 * force other threads to suicide. 308 */ 309 if (error == 0) 310 thread_single(SINGLE_EXIT); 311 else 312 thread_single_end(); 313 PROC_UNLOCK(p); 314 } 315 316 return (error); 317 } 318 319 /* 320 * In-kernel implementation of execve(). All arguments are assumed to be 321 * userspace pointers from the passed thread. 322 */ 323 static int 324 do_execve(td, args, mac_p) 325 struct thread *td; 326 struct image_args *args; 327 struct mac *mac_p; 328 { 329 struct proc *p = td->td_proc; 330 struct nameidata nd; 331 struct ucred *newcred = NULL, *oldcred; 332 struct uidinfo *euip; 333 register_t *stack_base; 334 int error, i; 335 struct image_params image_params, *imgp; 336 struct vattr attr; 337 int (*img_first)(struct image_params *); 338 struct pargs *oldargs = NULL, *newargs = NULL; 339 struct sigacts *oldsigacts, *newsigacts; 340 #ifdef KTRACE 341 struct vnode *tracevp = NULL; 342 struct ucred *tracecred = NULL; 343 #endif 344 struct vnode *textvp = NULL, *binvp = NULL; 345 cap_rights_t rights; 346 int credential_changing; 347 int textset; 348 #ifdef MAC 349 struct label *interpvplabel = NULL; 350 int will_transition; 351 #endif 352 #ifdef HWPMC_HOOKS 353 struct pmckern_procexec pe; 354 #endif 355 static const char fexecv_proc_title[] = "(fexecv)"; 356 357 imgp = &image_params; 358 359 /* 360 * Lock the process and set the P_INEXEC flag to indicate that 361 * it should be left alone until we're done here. This is 362 * necessary to avoid race conditions - e.g. in ptrace() - 363 * that might allow a local user to illicitly obtain elevated 364 * privileges. 365 */ 366 PROC_LOCK(p); 367 KASSERT((p->p_flag & P_INEXEC) == 0, 368 ("%s(): process already has P_INEXEC flag", __func__)); 369 p->p_flag |= P_INEXEC; 370 PROC_UNLOCK(p); 371 372 /* 373 * Initialize part of the common data 374 */ 375 imgp->proc = p; 376 imgp->execlabel = NULL; 377 imgp->attr = &attr; 378 imgp->entry_addr = 0; 379 imgp->reloc_base = 0; 380 imgp->vmspace_destroyed = 0; 381 imgp->interpreted = 0; 382 imgp->opened = 0; 383 imgp->interpreter_name = NULL; 384 imgp->auxargs = NULL; 385 imgp->vp = NULL; 386 imgp->object = NULL; 387 imgp->firstpage = NULL; 388 imgp->ps_strings = 0; 389 imgp->auxarg_size = 0; 390 imgp->args = args; 391 imgp->execpath = imgp->freepath = NULL; 392 imgp->execpathp = 0; 393 imgp->canary = 0; 394 imgp->canarylen = 0; 395 imgp->pagesizes = 0; 396 imgp->pagesizeslen = 0; 397 imgp->stack_prot = 0; 398 399 #ifdef MAC 400 error = mac_execve_enter(imgp, mac_p); 401 if (error) 402 goto exec_fail; 403 #endif 404 405 imgp->image_header = NULL; 406 407 /* 408 * Translate the file name. namei() returns a vnode pointer 409 * in ni_vp amoung other things. 410 * 411 * XXXAUDIT: It would be desirable to also audit the name of the 412 * interpreter if this is an interpreted binary. 413 */ 414 if (args->fname != NULL) { 415 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 416 | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 417 } 418 419 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 420 421 interpret: 422 if (args->fname != NULL) { 423 #ifdef CAPABILITY_MODE 424 /* 425 * While capability mode can't reach this point via direct 426 * path arguments to execve(), we also don't allow 427 * interpreters to be used in capability mode (for now). 428 * Catch indirect lookups and return a permissions error. 429 */ 430 if (IN_CAPABILITY_MODE(td)) { 431 error = ECAPMODE; 432 goto exec_fail; 433 } 434 #endif 435 error = namei(&nd); 436 if (error) 437 goto exec_fail; 438 439 binvp = nd.ni_vp; 440 imgp->vp = binvp; 441 } else { 442 AUDIT_ARG_FD(args->fd); 443 /* 444 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 445 */ 446 error = fgetvp_exec(td, args->fd, 447 cap_rights_init(&rights, CAP_FEXECVE), &binvp); 448 if (error) 449 goto exec_fail; 450 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY); 451 AUDIT_ARG_VNODE1(binvp); 452 imgp->vp = binvp; 453 } 454 455 /* 456 * Check file permissions (also 'opens' file) 457 */ 458 error = exec_check_permissions(imgp); 459 if (error) 460 goto exec_fail_dealloc; 461 462 imgp->object = imgp->vp->v_object; 463 if (imgp->object != NULL) 464 vm_object_reference(imgp->object); 465 466 /* 467 * Set VV_TEXT now so no one can write to the executable while we're 468 * activating it. 469 * 470 * Remember if this was set before and unset it in case this is not 471 * actually an executable image. 472 */ 473 textset = VOP_IS_TEXT(imgp->vp); 474 VOP_SET_TEXT(imgp->vp); 475 476 error = exec_map_first_page(imgp); 477 if (error) 478 goto exec_fail_dealloc; 479 480 imgp->proc->p_osrel = 0; 481 /* 482 * If the current process has a special image activator it 483 * wants to try first, call it. For example, emulating shell 484 * scripts differently. 485 */ 486 error = -1; 487 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 488 error = img_first(imgp); 489 490 /* 491 * Loop through the list of image activators, calling each one. 492 * An activator returns -1 if there is no match, 0 on success, 493 * and an error otherwise. 494 */ 495 for (i = 0; error == -1 && execsw[i]; ++i) { 496 if (execsw[i]->ex_imgact == NULL || 497 execsw[i]->ex_imgact == img_first) { 498 continue; 499 } 500 error = (*execsw[i]->ex_imgact)(imgp); 501 } 502 503 if (error) { 504 if (error == -1) { 505 if (textset == 0) 506 VOP_UNSET_TEXT(imgp->vp); 507 error = ENOEXEC; 508 } 509 goto exec_fail_dealloc; 510 } 511 512 /* 513 * Special interpreter operation, cleanup and loop up to try to 514 * activate the interpreter. 515 */ 516 if (imgp->interpreted) { 517 exec_unmap_first_page(imgp); 518 /* 519 * VV_TEXT needs to be unset for scripts. There is a short 520 * period before we determine that something is a script where 521 * VV_TEXT will be set. The vnode lock is held over this 522 * entire period so nothing should illegitimately be blocked. 523 */ 524 VOP_UNSET_TEXT(imgp->vp); 525 /* free name buffer and old vnode */ 526 if (args->fname != NULL) 527 NDFREE(&nd, NDF_ONLY_PNBUF); 528 #ifdef MAC 529 mac_execve_interpreter_enter(binvp, &interpvplabel); 530 #endif 531 if (imgp->opened) { 532 VOP_CLOSE(binvp, FREAD, td->td_ucred, td); 533 imgp->opened = 0; 534 } 535 vput(binvp); 536 vm_object_deallocate(imgp->object); 537 imgp->object = NULL; 538 /* set new name to that of the interpreter */ 539 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 540 UIO_SYSSPACE, imgp->interpreter_name, td); 541 args->fname = imgp->interpreter_name; 542 goto interpret; 543 } 544 545 /* 546 * NB: We unlock the vnode here because it is believed that none 547 * of the sv_copyout_strings/sv_fixup operations require the vnode. 548 */ 549 VOP_UNLOCK(imgp->vp, 0); 550 551 /* 552 * Do the best to calculate the full path to the image file. 553 */ 554 if (imgp->auxargs != NULL && 555 ((args->fname != NULL && args->fname[0] == '/') || 556 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0)) 557 imgp->execpath = args->fname; 558 559 if (disallow_high_osrel && 560 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 561 error = ENOEXEC; 562 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 563 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 564 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 565 goto exec_fail_dealloc; 566 } 567 568 /* 569 * Copy out strings (args and env) and initialize stack base 570 */ 571 if (p->p_sysent->sv_copyout_strings) 572 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 573 else 574 stack_base = exec_copyout_strings(imgp); 575 576 /* 577 * If custom stack fixup routine present for this process 578 * let it do the stack setup. 579 * Else stuff argument count as first item on stack 580 */ 581 if (p->p_sysent->sv_fixup != NULL) 582 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 583 else 584 suword(--stack_base, imgp->args->argc); 585 586 /* 587 * For security and other reasons, the file descriptor table cannot 588 * be shared after an exec. 589 */ 590 fdunshare(p, td); 591 592 /* 593 * Malloc things before we need locks. 594 */ 595 newcred = crget(); 596 euip = uifind(attr.va_uid); 597 i = imgp->args->begin_envv - imgp->args->begin_argv; 598 /* Cache arguments if they fit inside our allowance */ 599 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 600 newargs = pargs_alloc(i); 601 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 602 } 603 604 /* close files on exec */ 605 fdcloseexec(td); 606 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 607 608 /* Get a reference to the vnode prior to locking the proc */ 609 VREF(binvp); 610 611 /* 612 * For security and other reasons, signal handlers cannot 613 * be shared after an exec. The new process gets a copy of the old 614 * handlers. In execsigs(), the new process will have its signals 615 * reset. 616 */ 617 PROC_LOCK(p); 618 oldcred = crcopysafe(p, newcred); 619 if (sigacts_shared(p->p_sigacts)) { 620 oldsigacts = p->p_sigacts; 621 PROC_UNLOCK(p); 622 newsigacts = sigacts_alloc(); 623 sigacts_copy(newsigacts, oldsigacts); 624 PROC_LOCK(p); 625 p->p_sigacts = newsigacts; 626 } else 627 oldsigacts = NULL; 628 629 /* Stop profiling */ 630 stopprofclock(p); 631 632 /* reset caught signals */ 633 execsigs(p); 634 635 /* name this process - nameiexec(p, ndp) */ 636 bzero(p->p_comm, sizeof(p->p_comm)); 637 if (args->fname) 638 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 639 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 640 else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0) 641 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 642 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 643 #ifdef KTR 644 sched_clear_tdname(td); 645 #endif 646 647 /* 648 * mark as execed, wakeup the process that vforked (if any) and tell 649 * it that it now has its own resources back 650 */ 651 p->p_flag |= P_EXEC; 652 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 653 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 654 cv_broadcast(&p->p_pwait); 655 } 656 657 /* 658 * Implement image setuid/setgid. 659 * 660 * Don't honor setuid/setgid if the filesystem prohibits it or if 661 * the process is being traced. 662 * 663 * We disable setuid/setgid/etc in compatibility mode on the basis 664 * that most setugid applications are not written with that 665 * environment in mind, and will therefore almost certainly operate 666 * incorrectly. In principle there's no reason that setugid 667 * applications might not be useful in capability mode, so we may want 668 * to reconsider this conservative design choice in the future. 669 * 670 * XXXMAC: For the time being, use NOSUID to also prohibit 671 * transitions on the file system. 672 */ 673 credential_changing = 0; 674 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 675 attr.va_uid; 676 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 677 attr.va_gid; 678 #ifdef MAC 679 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 680 interpvplabel, imgp); 681 credential_changing |= will_transition; 682 #endif 683 684 if (credential_changing && 685 #ifdef CAPABILITY_MODE 686 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 687 #endif 688 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 689 (p->p_flag & P_TRACED) == 0) { 690 /* 691 * Turn off syscall tracing for set-id programs, except for 692 * root. Record any set-id flags first to make sure that 693 * we do not regain any tracing during a possible block. 694 */ 695 setsugid(p); 696 697 #ifdef KTRACE 698 if (p->p_tracecred != NULL && 699 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0)) 700 ktrprocexec(p, &tracecred, &tracevp); 701 #endif 702 /* 703 * Close any file descriptors 0..2 that reference procfs, 704 * then make sure file descriptors 0..2 are in use. 705 * 706 * setugidsafety() may call closef() and then pfind() 707 * which may grab the process lock. 708 * fdcheckstd() may call falloc() which may block to 709 * allocate memory, so temporarily drop the process lock. 710 */ 711 PROC_UNLOCK(p); 712 VOP_UNLOCK(imgp->vp, 0); 713 setugidsafety(td); 714 error = fdcheckstd(td); 715 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 716 if (error != 0) 717 goto done1; 718 PROC_LOCK(p); 719 /* 720 * Set the new credentials. 721 */ 722 if (attr.va_mode & S_ISUID) 723 change_euid(newcred, euip); 724 if (attr.va_mode & S_ISGID) 725 change_egid(newcred, attr.va_gid); 726 #ifdef MAC 727 if (will_transition) { 728 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 729 interpvplabel, imgp); 730 } 731 #endif 732 /* 733 * Implement correct POSIX saved-id behavior. 734 * 735 * XXXMAC: Note that the current logic will save the 736 * uid and gid if a MAC domain transition occurs, even 737 * though maybe it shouldn't. 738 */ 739 change_svuid(newcred, newcred->cr_uid); 740 change_svgid(newcred, newcred->cr_gid); 741 p->p_ucred = newcred; 742 newcred = NULL; 743 } else { 744 if (oldcred->cr_uid == oldcred->cr_ruid && 745 oldcred->cr_gid == oldcred->cr_rgid) 746 p->p_flag &= ~P_SUGID; 747 /* 748 * Implement correct POSIX saved-id behavior. 749 * 750 * XXX: It's not clear that the existing behavior is 751 * POSIX-compliant. A number of sources indicate that the 752 * saved uid/gid should only be updated if the new ruid is 753 * not equal to the old ruid, or the new euid is not equal 754 * to the old euid and the new euid is not equal to the old 755 * ruid. The FreeBSD code always updates the saved uid/gid. 756 * Also, this code uses the new (replaced) euid and egid as 757 * the source, which may or may not be the right ones to use. 758 */ 759 if (oldcred->cr_svuid != oldcred->cr_uid || 760 oldcred->cr_svgid != oldcred->cr_gid) { 761 change_svuid(newcred, newcred->cr_uid); 762 change_svgid(newcred, newcred->cr_gid); 763 p->p_ucred = newcred; 764 newcred = NULL; 765 } 766 } 767 768 /* 769 * Store the vp for use in procfs. This vnode was referenced prior 770 * to locking the proc lock. 771 */ 772 textvp = p->p_textvp; 773 p->p_textvp = binvp; 774 775 #ifdef KDTRACE_HOOKS 776 /* 777 * Tell the DTrace fasttrap provider about the exec if it 778 * has declared an interest. 779 */ 780 if (dtrace_fasttrap_exec) 781 dtrace_fasttrap_exec(p); 782 #endif 783 784 /* 785 * Notify others that we exec'd, and clear the P_INEXEC flag 786 * as we're now a bona fide freshly-execed process. 787 */ 788 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 789 p->p_flag &= ~P_INEXEC; 790 791 /* clear "fork but no exec" flag, as we _are_ execing */ 792 p->p_acflag &= ~AFORK; 793 794 /* 795 * Free any previous argument cache and replace it with 796 * the new argument cache, if any. 797 */ 798 oldargs = p->p_args; 799 p->p_args = newargs; 800 newargs = NULL; 801 802 #ifdef HWPMC_HOOKS 803 /* 804 * Check if system-wide sampling is in effect or if the 805 * current process is using PMCs. If so, do exec() time 806 * processing. This processing needs to happen AFTER the 807 * P_INEXEC flag is cleared. 808 * 809 * The proc lock needs to be released before taking the PMC 810 * SX. 811 */ 812 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 813 PROC_UNLOCK(p); 814 VOP_UNLOCK(imgp->vp, 0); 815 pe.pm_credentialschanged = credential_changing; 816 pe.pm_entryaddr = imgp->entry_addr; 817 818 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 819 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 820 } else 821 PROC_UNLOCK(p); 822 #else /* !HWPMC_HOOKS */ 823 PROC_UNLOCK(p); 824 #endif 825 826 /* Set values passed into the program in registers. */ 827 if (p->p_sysent->sv_setregs) 828 (*p->p_sysent->sv_setregs)(td, imgp, 829 (u_long)(uintptr_t)stack_base); 830 else 831 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 832 833 vfs_mark_atime(imgp->vp, td->td_ucred); 834 835 SDT_PROBE(proc, kernel, , exec__success, args->fname, 0, 0, 0, 0); 836 837 done1: 838 /* 839 * Free any resources malloc'd earlier that we didn't use. 840 */ 841 uifree(euip); 842 if (newcred == NULL) 843 crfree(oldcred); 844 else 845 crfree(newcred); 846 VOP_UNLOCK(imgp->vp, 0); 847 848 /* 849 * Handle deferred decrement of ref counts. 850 */ 851 if (textvp != NULL) 852 vrele(textvp); 853 if (binvp && error != 0) 854 vrele(binvp); 855 #ifdef KTRACE 856 if (tracevp != NULL) 857 vrele(tracevp); 858 if (tracecred != NULL) 859 crfree(tracecred); 860 #endif 861 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 862 pargs_drop(oldargs); 863 pargs_drop(newargs); 864 if (oldsigacts != NULL) 865 sigacts_free(oldsigacts); 866 867 exec_fail_dealloc: 868 869 /* 870 * free various allocated resources 871 */ 872 if (imgp->firstpage != NULL) 873 exec_unmap_first_page(imgp); 874 875 if (imgp->vp != NULL) { 876 if (args->fname) 877 NDFREE(&nd, NDF_ONLY_PNBUF); 878 if (imgp->opened) 879 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 880 vput(imgp->vp); 881 } 882 883 if (imgp->object != NULL) 884 vm_object_deallocate(imgp->object); 885 886 free(imgp->freepath, M_TEMP); 887 888 if (error == 0) { 889 PROC_LOCK(p); 890 td->td_dbgflags |= TDB_EXEC; 891 PROC_UNLOCK(p); 892 893 /* 894 * Stop the process here if its stop event mask has 895 * the S_EXEC bit set. 896 */ 897 STOPEVENT(p, S_EXEC, 0); 898 goto done2; 899 } 900 901 exec_fail: 902 /* we're done here, clear P_INEXEC */ 903 PROC_LOCK(p); 904 p->p_flag &= ~P_INEXEC; 905 PROC_UNLOCK(p); 906 907 SDT_PROBE(proc, kernel, , exec__failure, error, 0, 0, 0, 0); 908 909 done2: 910 #ifdef MAC 911 mac_execve_exit(imgp); 912 mac_execve_interpreter_exit(interpvplabel); 913 #endif 914 exec_free_args(args); 915 916 if (error && imgp->vmspace_destroyed) { 917 /* sorry, no more process anymore. exit gracefully */ 918 exit1(td, W_EXITCODE(0, SIGABRT)); 919 /* NOT REACHED */ 920 } 921 922 #ifdef KTRACE 923 if (error == 0) 924 ktrprocctor(p); 925 #endif 926 927 return (error); 928 } 929 930 int 931 exec_map_first_page(imgp) 932 struct image_params *imgp; 933 { 934 int rv, i; 935 int initial_pagein; 936 vm_page_t ma[VM_INITIAL_PAGEIN]; 937 vm_object_t object; 938 939 if (imgp->firstpage != NULL) 940 exec_unmap_first_page(imgp); 941 942 object = imgp->vp->v_object; 943 if (object == NULL) 944 return (EACCES); 945 VM_OBJECT_WLOCK(object); 946 #if VM_NRESERVLEVEL > 0 947 if ((object->flags & OBJ_COLORED) == 0) { 948 object->flags |= OBJ_COLORED; 949 object->pg_color = 0; 950 } 951 #endif 952 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL); 953 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 954 initial_pagein = VM_INITIAL_PAGEIN; 955 if (initial_pagein > object->size) 956 initial_pagein = object->size; 957 for (i = 1; i < initial_pagein; i++) { 958 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 959 if (ma[i]->valid) 960 break; 961 if (vm_page_tryxbusy(ma[i])) 962 break; 963 } else { 964 ma[i] = vm_page_alloc(object, i, 965 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 966 if (ma[i] == NULL) 967 break; 968 } 969 } 970 initial_pagein = i; 971 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 972 ma[0] = vm_page_lookup(object, 0); 973 if ((rv != VM_PAGER_OK) || (ma[0] == NULL)) { 974 if (ma[0] != NULL) { 975 vm_page_lock(ma[0]); 976 vm_page_free(ma[0]); 977 vm_page_unlock(ma[0]); 978 } 979 VM_OBJECT_WUNLOCK(object); 980 return (EIO); 981 } 982 } 983 vm_page_xunbusy(ma[0]); 984 vm_page_lock(ma[0]); 985 vm_page_hold(ma[0]); 986 vm_page_unlock(ma[0]); 987 VM_OBJECT_WUNLOCK(object); 988 989 imgp->firstpage = sf_buf_alloc(ma[0], 0); 990 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 991 992 return (0); 993 } 994 995 void 996 exec_unmap_first_page(imgp) 997 struct image_params *imgp; 998 { 999 vm_page_t m; 1000 1001 if (imgp->firstpage != NULL) { 1002 m = sf_buf_page(imgp->firstpage); 1003 sf_buf_free(imgp->firstpage); 1004 imgp->firstpage = NULL; 1005 vm_page_lock(m); 1006 vm_page_unhold(m); 1007 vm_page_unlock(m); 1008 } 1009 } 1010 1011 /* 1012 * Destroy old address space, and allocate a new stack 1013 * The new stack is only SGROWSIZ large because it is grown 1014 * automatically in trap.c. 1015 */ 1016 int 1017 exec_new_vmspace(imgp, sv) 1018 struct image_params *imgp; 1019 struct sysentvec *sv; 1020 { 1021 int error; 1022 struct proc *p = imgp->proc; 1023 struct vmspace *vmspace = p->p_vmspace; 1024 vm_object_t obj; 1025 vm_offset_t sv_minuser, stack_addr; 1026 vm_map_t map; 1027 u_long ssiz; 1028 1029 imgp->vmspace_destroyed = 1; 1030 imgp->sysent = sv; 1031 1032 /* May be called with Giant held */ 1033 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1034 1035 /* 1036 * Blow away entire process VM, if address space not shared, 1037 * otherwise, create a new VM space so that other threads are 1038 * not disrupted 1039 */ 1040 map = &vmspace->vm_map; 1041 if (map_at_zero) 1042 sv_minuser = sv->sv_minuser; 1043 else 1044 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1045 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1046 vm_map_max(map) == sv->sv_maxuser) { 1047 shmexit(vmspace); 1048 pmap_remove_pages(vmspace_pmap(vmspace)); 1049 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1050 } else { 1051 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1052 if (error) 1053 return (error); 1054 vmspace = p->p_vmspace; 1055 map = &vmspace->vm_map; 1056 } 1057 1058 /* Map a shared page */ 1059 obj = sv->sv_shared_page_obj; 1060 if (obj != NULL) { 1061 vm_object_reference(obj); 1062 error = vm_map_fixed(map, obj, 0, 1063 sv->sv_shared_page_base, sv->sv_shared_page_len, 1064 VM_PROT_READ | VM_PROT_EXECUTE, 1065 VM_PROT_READ | VM_PROT_EXECUTE, 1066 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1067 if (error) { 1068 vm_object_deallocate(obj); 1069 return (error); 1070 } 1071 } 1072 1073 /* Allocate a new stack */ 1074 if (sv->sv_maxssiz != NULL) 1075 ssiz = *sv->sv_maxssiz; 1076 else 1077 ssiz = maxssiz; 1078 stack_addr = sv->sv_usrstack - ssiz; 1079 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1080 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1081 sv->sv_stackprot, 1082 VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1083 if (error) 1084 return (error); 1085 1086 #ifdef __ia64__ 1087 /* Allocate a new register stack */ 1088 stack_addr = IA64_BACKINGSTORE; 1089 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1090 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP); 1091 if (error) 1092 return (error); 1093 #endif 1094 1095 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 1096 * VM_STACK case, but they are still used to monitor the size of the 1097 * process stack so we can check the stack rlimit. 1098 */ 1099 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1100 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1101 1102 return (0); 1103 } 1104 1105 /* 1106 * Copy out argument and environment strings from the old process address 1107 * space into the temporary string buffer. 1108 */ 1109 int 1110 exec_copyin_args(struct image_args *args, char *fname, 1111 enum uio_seg segflg, char **argv, char **envv) 1112 { 1113 char *argp, *envp; 1114 int error; 1115 size_t length; 1116 1117 bzero(args, sizeof(*args)); 1118 if (argv == NULL) 1119 return (EFAULT); 1120 1121 /* 1122 * Allocate demand-paged memory for the file name, argument, and 1123 * environment strings. 1124 */ 1125 error = exec_alloc_args(args); 1126 if (error != 0) 1127 return (error); 1128 1129 /* 1130 * Copy the file name. 1131 */ 1132 if (fname != NULL) { 1133 args->fname = args->buf; 1134 error = (segflg == UIO_SYSSPACE) ? 1135 copystr(fname, args->fname, PATH_MAX, &length) : 1136 copyinstr(fname, args->fname, PATH_MAX, &length); 1137 if (error != 0) 1138 goto err_exit; 1139 } else 1140 length = 0; 1141 1142 args->begin_argv = args->buf + length; 1143 args->endp = args->begin_argv; 1144 args->stringspace = ARG_MAX; 1145 1146 /* 1147 * extract arguments first 1148 */ 1149 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 1150 if (argp == (caddr_t) -1) { 1151 error = EFAULT; 1152 goto err_exit; 1153 } 1154 if ((error = copyinstr(argp, args->endp, 1155 args->stringspace, &length))) { 1156 if (error == ENAMETOOLONG) 1157 error = E2BIG; 1158 goto err_exit; 1159 } 1160 args->stringspace -= length; 1161 args->endp += length; 1162 args->argc++; 1163 } 1164 1165 args->begin_envv = args->endp; 1166 1167 /* 1168 * extract environment strings 1169 */ 1170 if (envv) { 1171 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) { 1172 if (envp == (caddr_t)-1) { 1173 error = EFAULT; 1174 goto err_exit; 1175 } 1176 if ((error = copyinstr(envp, args->endp, 1177 args->stringspace, &length))) { 1178 if (error == ENAMETOOLONG) 1179 error = E2BIG; 1180 goto err_exit; 1181 } 1182 args->stringspace -= length; 1183 args->endp += length; 1184 args->envc++; 1185 } 1186 } 1187 1188 return (0); 1189 1190 err_exit: 1191 exec_free_args(args); 1192 return (error); 1193 } 1194 1195 /* 1196 * Allocate temporary demand-paged, zero-filled memory for the file name, 1197 * argument, and environment strings. Returns zero if the allocation succeeds 1198 * and ENOMEM otherwise. 1199 */ 1200 int 1201 exec_alloc_args(struct image_args *args) 1202 { 1203 1204 args->buf = (char *)kmap_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 1205 return (args->buf != NULL ? 0 : ENOMEM); 1206 } 1207 1208 void 1209 exec_free_args(struct image_args *args) 1210 { 1211 1212 if (args->buf != NULL) { 1213 kmap_free_wakeup(exec_map, (vm_offset_t)args->buf, 1214 PATH_MAX + ARG_MAX); 1215 args->buf = NULL; 1216 } 1217 if (args->fname_buf != NULL) { 1218 free(args->fname_buf, M_TEMP); 1219 args->fname_buf = NULL; 1220 } 1221 } 1222 1223 /* 1224 * Copy strings out to the new process address space, constructing new arg 1225 * and env vector tables. Return a pointer to the base so that it can be used 1226 * as the initial stack pointer. 1227 */ 1228 register_t * 1229 exec_copyout_strings(imgp) 1230 struct image_params *imgp; 1231 { 1232 int argc, envc; 1233 char **vectp; 1234 char *stringp, *destp; 1235 register_t *stack_base; 1236 struct ps_strings *arginfo; 1237 struct proc *p; 1238 size_t execpath_len; 1239 int szsigcode, szps; 1240 char canary[sizeof(long) * 8]; 1241 1242 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1243 /* 1244 * Calculate string base and vector table pointers. 1245 * Also deal with signal trampoline code for this exec type. 1246 */ 1247 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1248 execpath_len = strlen(imgp->execpath) + 1; 1249 else 1250 execpath_len = 0; 1251 p = imgp->proc; 1252 szsigcode = 0; 1253 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1254 if (p->p_sysent->sv_sigcode_base == 0) { 1255 if (p->p_sysent->sv_szsigcode != NULL) 1256 szsigcode = *(p->p_sysent->sv_szsigcode); 1257 } 1258 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 1259 roundup(execpath_len, sizeof(char *)) - 1260 roundup(sizeof(canary), sizeof(char *)) - 1261 roundup(szps, sizeof(char *)) - 1262 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *)); 1263 1264 /* 1265 * install sigcode 1266 */ 1267 if (szsigcode != 0) 1268 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo - 1269 szsigcode), szsigcode); 1270 1271 /* 1272 * Copy the image path for the rtld. 1273 */ 1274 if (execpath_len != 0) { 1275 imgp->execpathp = (uintptr_t)arginfo - szsigcode - execpath_len; 1276 copyout(imgp->execpath, (void *)imgp->execpathp, 1277 execpath_len); 1278 } 1279 1280 /* 1281 * Prepare the canary for SSP. 1282 */ 1283 arc4rand(canary, sizeof(canary), 0); 1284 imgp->canary = (uintptr_t)arginfo - szsigcode - execpath_len - 1285 sizeof(canary); 1286 copyout(canary, (void *)imgp->canary, sizeof(canary)); 1287 imgp->canarylen = sizeof(canary); 1288 1289 /* 1290 * Prepare the pagesizes array. 1291 */ 1292 imgp->pagesizes = (uintptr_t)arginfo - szsigcode - execpath_len - 1293 roundup(sizeof(canary), sizeof(char *)) - szps; 1294 copyout(pagesizes, (void *)imgp->pagesizes, szps); 1295 imgp->pagesizeslen = szps; 1296 1297 /* 1298 * If we have a valid auxargs ptr, prepare some room 1299 * on the stack. 1300 */ 1301 if (imgp->auxargs) { 1302 /* 1303 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1304 * lower compatibility. 1305 */ 1306 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1307 (AT_COUNT * 2); 1308 /* 1309 * The '+ 2' is for the null pointers at the end of each of 1310 * the arg and env vector sets,and imgp->auxarg_size is room 1311 * for argument of Runtime loader. 1312 */ 1313 vectp = (char **)(destp - (imgp->args->argc + 1314 imgp->args->envc + 2 + imgp->auxarg_size) 1315 * sizeof(char *)); 1316 } else { 1317 /* 1318 * The '+ 2' is for the null pointers at the end of each of 1319 * the arg and env vector sets 1320 */ 1321 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) * 1322 sizeof(char *)); 1323 } 1324 1325 /* 1326 * vectp also becomes our initial stack base 1327 */ 1328 stack_base = (register_t *)vectp; 1329 1330 stringp = imgp->args->begin_argv; 1331 argc = imgp->args->argc; 1332 envc = imgp->args->envc; 1333 1334 /* 1335 * Copy out strings - arguments and environment. 1336 */ 1337 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace); 1338 1339 /* 1340 * Fill in "ps_strings" struct for ps, w, etc. 1341 */ 1342 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1343 suword32(&arginfo->ps_nargvstr, argc); 1344 1345 /* 1346 * Fill in argument portion of vector table. 1347 */ 1348 for (; argc > 0; --argc) { 1349 suword(vectp++, (long)(intptr_t)destp); 1350 while (*stringp++ != 0) 1351 destp++; 1352 destp++; 1353 } 1354 1355 /* a null vector table pointer separates the argp's from the envp's */ 1356 suword(vectp++, 0); 1357 1358 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1359 suword32(&arginfo->ps_nenvstr, envc); 1360 1361 /* 1362 * Fill in environment portion of vector table. 1363 */ 1364 for (; envc > 0; --envc) { 1365 suword(vectp++, (long)(intptr_t)destp); 1366 while (*stringp++ != 0) 1367 destp++; 1368 destp++; 1369 } 1370 1371 /* end of vector table is a null pointer */ 1372 suword(vectp, 0); 1373 1374 return (stack_base); 1375 } 1376 1377 /* 1378 * Check permissions of file to execute. 1379 * Called with imgp->vp locked. 1380 * Return 0 for success or error code on failure. 1381 */ 1382 int 1383 exec_check_permissions(imgp) 1384 struct image_params *imgp; 1385 { 1386 struct vnode *vp = imgp->vp; 1387 struct vattr *attr = imgp->attr; 1388 struct thread *td; 1389 int error, writecount; 1390 1391 td = curthread; 1392 1393 /* Get file attributes */ 1394 error = VOP_GETATTR(vp, attr, td->td_ucred); 1395 if (error) 1396 return (error); 1397 1398 #ifdef MAC 1399 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1400 if (error) 1401 return (error); 1402 #endif 1403 1404 /* 1405 * 1) Check if file execution is disabled for the filesystem that 1406 * this file resides on. 1407 * 2) Ensure that at least one execute bit is on. Otherwise, a 1408 * privileged user will always succeed, and we don't want this 1409 * to happen unless the file really is executable. 1410 * 3) Ensure that the file is a regular file. 1411 */ 1412 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1413 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1414 (attr->va_type != VREG)) 1415 return (EACCES); 1416 1417 /* 1418 * Zero length files can't be exec'd 1419 */ 1420 if (attr->va_size == 0) 1421 return (ENOEXEC); 1422 1423 /* 1424 * Check for execute permission to file based on current credentials. 1425 */ 1426 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1427 if (error) 1428 return (error); 1429 1430 /* 1431 * Check number of open-for-writes on the file and deny execution 1432 * if there are any. 1433 */ 1434 error = VOP_GET_WRITECOUNT(vp, &writecount); 1435 if (error != 0) 1436 return (error); 1437 if (writecount != 0) 1438 return (ETXTBSY); 1439 1440 /* 1441 * Call filesystem specific open routine (which does nothing in the 1442 * general case). 1443 */ 1444 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1445 if (error == 0) 1446 imgp->opened = 1; 1447 return (error); 1448 } 1449 1450 /* 1451 * Exec handler registration 1452 */ 1453 int 1454 exec_register(execsw_arg) 1455 const struct execsw *execsw_arg; 1456 { 1457 const struct execsw **es, **xs, **newexecsw; 1458 int count = 2; /* New slot and trailing NULL */ 1459 1460 if (execsw) 1461 for (es = execsw; *es; es++) 1462 count++; 1463 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1464 if (newexecsw == NULL) 1465 return (ENOMEM); 1466 xs = newexecsw; 1467 if (execsw) 1468 for (es = execsw; *es; es++) 1469 *xs++ = *es; 1470 *xs++ = execsw_arg; 1471 *xs = NULL; 1472 if (execsw) 1473 free(execsw, M_TEMP); 1474 execsw = newexecsw; 1475 return (0); 1476 } 1477 1478 int 1479 exec_unregister(execsw_arg) 1480 const struct execsw *execsw_arg; 1481 { 1482 const struct execsw **es, **xs, **newexecsw; 1483 int count = 1; 1484 1485 if (execsw == NULL) 1486 panic("unregister with no handlers left?\n"); 1487 1488 for (es = execsw; *es; es++) { 1489 if (*es == execsw_arg) 1490 break; 1491 } 1492 if (*es == NULL) 1493 return (ENOENT); 1494 for (es = execsw; *es; es++) 1495 if (*es != execsw_arg) 1496 count++; 1497 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1498 if (newexecsw == NULL) 1499 return (ENOMEM); 1500 xs = newexecsw; 1501 for (es = execsw; *es; es++) 1502 if (*es != execsw_arg) 1503 *xs++ = *es; 1504 *xs = NULL; 1505 if (execsw) 1506 free(execsw, M_TEMP); 1507 execsw = newexecsw; 1508 return (0); 1509 } 1510