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 = NULL; 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 imgp->proc = p; 383 imgp->execlabel = NULL; 384 imgp->attr = &attr; 385 imgp->entry_addr = 0; 386 imgp->reloc_base = 0; 387 imgp->vmspace_destroyed = 0; 388 imgp->interpreted = 0; 389 imgp->opened = 0; 390 imgp->interpreter_name = NULL; 391 imgp->auxargs = NULL; 392 imgp->vp = NULL; 393 imgp->object = NULL; 394 imgp->firstpage = NULL; 395 imgp->ps_strings = 0; 396 imgp->auxarg_size = 0; 397 imgp->args = args; 398 imgp->execpath = imgp->freepath = NULL; 399 imgp->execpathp = 0; 400 imgp->canary = 0; 401 imgp->canarylen = 0; 402 imgp->pagesizes = 0; 403 imgp->pagesizeslen = 0; 404 imgp->stack_prot = 0; 405 406 #ifdef MAC 407 error = mac_execve_enter(imgp, mac_p); 408 if (error) 409 goto exec_fail; 410 #endif 411 412 imgp->image_header = NULL; 413 414 /* 415 * Translate the file name. namei() returns a vnode pointer 416 * in ni_vp amoung other things. 417 * 418 * XXXAUDIT: It would be desirable to also audit the name of the 419 * interpreter if this is an interpreted binary. 420 */ 421 if (args->fname != NULL) { 422 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 423 | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 424 } 425 426 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 427 428 interpret: 429 if (args->fname != NULL) { 430 #ifdef CAPABILITY_MODE 431 /* 432 * While capability mode can't reach this point via direct 433 * path arguments to execve(), we also don't allow 434 * interpreters to be used in capability mode (for now). 435 * Catch indirect lookups and return a permissions error. 436 */ 437 if (IN_CAPABILITY_MODE(td)) { 438 error = ECAPMODE; 439 goto exec_fail; 440 } 441 #endif 442 error = namei(&nd); 443 if (error) 444 goto exec_fail; 445 446 binvp = nd.ni_vp; 447 imgp->vp = binvp; 448 } else { 449 AUDIT_ARG_FD(args->fd); 450 /* 451 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 452 */ 453 error = fgetvp_exec(td, args->fd, 454 cap_rights_init(&rights, CAP_FEXECVE), &binvp); 455 if (error) 456 goto exec_fail; 457 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY); 458 AUDIT_ARG_VNODE1(binvp); 459 imgp->vp = binvp; 460 } 461 462 /* 463 * Check file permissions (also 'opens' file) 464 */ 465 error = exec_check_permissions(imgp); 466 if (error) 467 goto exec_fail_dealloc; 468 469 imgp->object = imgp->vp->v_object; 470 if (imgp->object != NULL) 471 vm_object_reference(imgp->object); 472 473 /* 474 * Set VV_TEXT now so no one can write to the executable while we're 475 * activating it. 476 * 477 * Remember if this was set before and unset it in case this is not 478 * actually an executable image. 479 */ 480 textset = VOP_IS_TEXT(imgp->vp); 481 VOP_SET_TEXT(imgp->vp); 482 483 error = exec_map_first_page(imgp); 484 if (error) 485 goto exec_fail_dealloc; 486 487 imgp->proc->p_osrel = 0; 488 /* 489 * If the current process has a special image activator it 490 * wants to try first, call it. For example, emulating shell 491 * scripts differently. 492 */ 493 error = -1; 494 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 495 error = img_first(imgp); 496 497 /* 498 * Loop through the list of image activators, calling each one. 499 * An activator returns -1 if there is no match, 0 on success, 500 * and an error otherwise. 501 */ 502 for (i = 0; error == -1 && execsw[i]; ++i) { 503 if (execsw[i]->ex_imgact == NULL || 504 execsw[i]->ex_imgact == img_first) { 505 continue; 506 } 507 error = (*execsw[i]->ex_imgact)(imgp); 508 } 509 510 if (error) { 511 if (error == -1) { 512 if (textset == 0) 513 VOP_UNSET_TEXT(imgp->vp); 514 error = ENOEXEC; 515 } 516 goto exec_fail_dealloc; 517 } 518 519 /* 520 * Special interpreter operation, cleanup and loop up to try to 521 * activate the interpreter. 522 */ 523 if (imgp->interpreted) { 524 exec_unmap_first_page(imgp); 525 /* 526 * VV_TEXT needs to be unset for scripts. There is a short 527 * period before we determine that something is a script where 528 * VV_TEXT will be set. The vnode lock is held over this 529 * entire period so nothing should illegitimately be blocked. 530 */ 531 VOP_UNSET_TEXT(imgp->vp); 532 /* free name buffer and old vnode */ 533 if (args->fname != NULL) 534 NDFREE(&nd, NDF_ONLY_PNBUF); 535 #ifdef MAC 536 mac_execve_interpreter_enter(binvp, &interpvplabel); 537 #endif 538 if (imgp->opened) { 539 VOP_CLOSE(binvp, FREAD, td->td_ucred, td); 540 imgp->opened = 0; 541 } 542 vput(binvp); 543 vm_object_deallocate(imgp->object); 544 imgp->object = NULL; 545 /* set new name to that of the interpreter */ 546 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 547 UIO_SYSSPACE, imgp->interpreter_name, td); 548 args->fname = imgp->interpreter_name; 549 goto interpret; 550 } 551 552 /* 553 * NB: We unlock the vnode here because it is believed that none 554 * of the sv_copyout_strings/sv_fixup operations require the vnode. 555 */ 556 VOP_UNLOCK(imgp->vp, 0); 557 558 /* 559 * Do the best to calculate the full path to the image file. 560 */ 561 if (imgp->auxargs != NULL && 562 ((args->fname != NULL && args->fname[0] == '/') || 563 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0)) 564 imgp->execpath = args->fname; 565 566 if (disallow_high_osrel && 567 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 568 error = ENOEXEC; 569 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 570 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 571 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 572 goto exec_fail_dealloc; 573 } 574 575 /* 576 * Copy out strings (args and env) and initialize stack base 577 */ 578 if (p->p_sysent->sv_copyout_strings) 579 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 580 else 581 stack_base = exec_copyout_strings(imgp); 582 583 /* 584 * If custom stack fixup routine present for this process 585 * let it do the stack setup. 586 * Else stuff argument count as first item on stack 587 */ 588 if (p->p_sysent->sv_fixup != NULL) 589 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 590 else 591 suword(--stack_base, imgp->args->argc); 592 593 /* 594 * For security and other reasons, the file descriptor table cannot 595 * be shared after an exec. 596 */ 597 fdunshare(td); 598 /* close files on exec */ 599 fdcloseexec(td); 600 601 /* 602 * Malloc things before we need locks. 603 */ 604 i = imgp->args->begin_envv - imgp->args->begin_argv; 605 /* Cache arguments if they fit inside our allowance */ 606 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 607 newargs = pargs_alloc(i); 608 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 609 } 610 611 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 612 613 /* Get a reference to the vnode prior to locking the proc */ 614 VREF(binvp); 615 616 /* 617 * For security and other reasons, signal handlers cannot 618 * be shared after an exec. The new process gets a copy of the old 619 * handlers. In execsigs(), the new process will have its signals 620 * reset. 621 */ 622 if (sigacts_shared(p->p_sigacts)) { 623 oldsigacts = p->p_sigacts; 624 newsigacts = sigacts_alloc(); 625 sigacts_copy(newsigacts, oldsigacts); 626 } else { 627 oldsigacts = NULL; 628 newsigacts = NULL; /* satisfy gcc */ 629 } 630 631 PROC_LOCK(p); 632 if (oldsigacts) 633 p->p_sigacts = newsigacts; 634 oldcred = p->p_ucred; 635 /* Stop profiling */ 636 stopprofclock(p); 637 638 /* reset caught signals */ 639 execsigs(p); 640 641 /* name this process - nameiexec(p, ndp) */ 642 bzero(p->p_comm, sizeof(p->p_comm)); 643 if (args->fname) 644 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 645 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 646 else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0) 647 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 648 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 649 #ifdef KTR 650 sched_clear_tdname(td); 651 #endif 652 653 /* 654 * mark as execed, wakeup the process that vforked (if any) and tell 655 * it that it now has its own resources back 656 */ 657 p->p_flag |= P_EXEC; 658 if (p->p_flag & P_PPWAIT) { 659 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 660 cv_broadcast(&p->p_pwait); 661 } 662 663 /* 664 * Implement image setuid/setgid. 665 * 666 * Don't honor setuid/setgid if the filesystem prohibits it or if 667 * the process is being traced. 668 * 669 * We disable setuid/setgid/etc in compatibility mode on the basis 670 * that most setugid applications are not written with that 671 * environment in mind, and will therefore almost certainly operate 672 * incorrectly. In principle there's no reason that setugid 673 * applications might not be useful in capability mode, so we may want 674 * to reconsider this conservative design choice in the future. 675 * 676 * XXXMAC: For the time being, use NOSUID to also prohibit 677 * transitions on the file system. 678 */ 679 credential_changing = 0; 680 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 681 attr.va_uid; 682 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 683 attr.va_gid; 684 #ifdef MAC 685 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 686 interpvplabel, imgp); 687 credential_changing |= will_transition; 688 #endif 689 690 if (credential_changing && 691 #ifdef CAPABILITY_MODE 692 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 693 #endif 694 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 695 (p->p_flag & P_TRACED) == 0) { 696 /* 697 * Turn off syscall tracing for set-id programs, except for 698 * root. Record any set-id flags first to make sure that 699 * we do not regain any tracing during a possible block. 700 */ 701 setsugid(p); 702 703 #ifdef KTRACE 704 if (p->p_tracecred != NULL && 705 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0)) 706 ktrprocexec(p, &tracecred, &tracevp); 707 #endif 708 /* 709 * Close any file descriptors 0..2 that reference procfs, 710 * then make sure file descriptors 0..2 are in use. 711 * 712 * setugidsafety() may call closef() and then pfind() 713 * which may grab the process lock. 714 * fdcheckstd() may call falloc() which may block to 715 * allocate memory, so temporarily drop the process lock. 716 */ 717 PROC_UNLOCK(p); 718 VOP_UNLOCK(imgp->vp, 0); 719 setugidsafety(td); 720 error = fdcheckstd(td); 721 if (error != 0) 722 goto done1; 723 newcred = crdup(oldcred); 724 euip = uifind(attr.va_uid); 725 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 726 PROC_LOCK(p); 727 /* 728 * Set the new credentials. 729 */ 730 if (attr.va_mode & S_ISUID) 731 change_euid(newcred, euip); 732 if (attr.va_mode & S_ISGID) 733 change_egid(newcred, attr.va_gid); 734 #ifdef MAC 735 if (will_transition) { 736 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 737 interpvplabel, imgp); 738 } 739 #endif 740 /* 741 * Implement correct POSIX saved-id behavior. 742 * 743 * XXXMAC: Note that the current logic will save the 744 * uid and gid if a MAC domain transition occurs, even 745 * though maybe it shouldn't. 746 */ 747 change_svuid(newcred, newcred->cr_uid); 748 change_svgid(newcred, newcred->cr_gid); 749 p->p_ucred = newcred; 750 } else { 751 if (oldcred->cr_uid == oldcred->cr_ruid && 752 oldcred->cr_gid == oldcred->cr_rgid) 753 p->p_flag &= ~P_SUGID; 754 /* 755 * Implement correct POSIX saved-id behavior. 756 * 757 * XXX: It's not clear that the existing behavior is 758 * POSIX-compliant. A number of sources indicate that the 759 * saved uid/gid should only be updated if the new ruid is 760 * not equal to the old ruid, or the new euid is not equal 761 * to the old euid and the new euid is not equal to the old 762 * ruid. The FreeBSD code always updates the saved uid/gid. 763 * Also, this code uses the new (replaced) euid and egid as 764 * the source, which may or may not be the right ones to use. 765 */ 766 if (oldcred->cr_svuid != oldcred->cr_uid || 767 oldcred->cr_svgid != oldcred->cr_gid) { 768 PROC_UNLOCK(p); 769 VOP_UNLOCK(imgp->vp, 0); 770 newcred = crdup(oldcred); 771 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 772 PROC_LOCK(p); 773 change_svuid(newcred, newcred->cr_uid); 774 change_svgid(newcred, newcred->cr_gid); 775 p->p_ucred = newcred; 776 } 777 } 778 779 /* 780 * Store the vp for use in procfs. This vnode was referenced prior 781 * to locking the proc lock. 782 */ 783 textvp = p->p_textvp; 784 p->p_textvp = binvp; 785 786 #ifdef KDTRACE_HOOKS 787 /* 788 * Tell the DTrace fasttrap provider about the exec if it 789 * has declared an interest. 790 */ 791 if (dtrace_fasttrap_exec) 792 dtrace_fasttrap_exec(p); 793 #endif 794 795 /* 796 * Notify others that we exec'd, and clear the P_INEXEC flag 797 * as we're now a bona fide freshly-execed process. 798 */ 799 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 800 p->p_flag &= ~P_INEXEC; 801 802 /* clear "fork but no exec" flag, as we _are_ execing */ 803 p->p_acflag &= ~AFORK; 804 805 /* 806 * Free any previous argument cache and replace it with 807 * the new argument cache, if any. 808 */ 809 oldargs = p->p_args; 810 p->p_args = newargs; 811 newargs = NULL; 812 813 #ifdef HWPMC_HOOKS 814 /* 815 * Check if system-wide sampling is in effect or if the 816 * current process is using PMCs. If so, do exec() time 817 * processing. This processing needs to happen AFTER the 818 * P_INEXEC flag is cleared. 819 * 820 * The proc lock needs to be released before taking the PMC 821 * SX. 822 */ 823 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 824 PROC_UNLOCK(p); 825 VOP_UNLOCK(imgp->vp, 0); 826 pe.pm_credentialschanged = credential_changing; 827 pe.pm_entryaddr = imgp->entry_addr; 828 829 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 830 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 831 } else 832 PROC_UNLOCK(p); 833 #else /* !HWPMC_HOOKS */ 834 PROC_UNLOCK(p); 835 #endif 836 837 /* Set values passed into the program in registers. */ 838 if (p->p_sysent->sv_setregs) 839 (*p->p_sysent->sv_setregs)(td, imgp, 840 (u_long)(uintptr_t)stack_base); 841 else 842 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 843 844 vfs_mark_atime(imgp->vp, td->td_ucred); 845 846 SDT_PROBE(proc, kernel, , exec__success, args->fname, 0, 0, 0, 0); 847 848 VOP_UNLOCK(imgp->vp, 0); 849 done1: 850 /* 851 * Free any resources malloc'd earlier that we didn't use. 852 */ 853 if (euip != NULL) 854 uifree(euip); 855 if (newcred != NULL) 856 crfree(oldcred); 857 858 /* 859 * Handle deferred decrement of ref counts. 860 */ 861 if (textvp != NULL) 862 vrele(textvp); 863 if (binvp && error != 0) 864 vrele(binvp); 865 #ifdef KTRACE 866 if (tracevp != NULL) 867 vrele(tracevp); 868 if (tracecred != NULL) 869 crfree(tracecred); 870 #endif 871 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 872 pargs_drop(oldargs); 873 pargs_drop(newargs); 874 if (oldsigacts != NULL) 875 sigacts_free(oldsigacts); 876 877 exec_fail_dealloc: 878 879 /* 880 * free various allocated resources 881 */ 882 if (imgp->firstpage != NULL) 883 exec_unmap_first_page(imgp); 884 885 if (imgp->vp != NULL) { 886 if (args->fname) 887 NDFREE(&nd, NDF_ONLY_PNBUF); 888 if (imgp->opened) 889 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 890 vput(imgp->vp); 891 } 892 893 if (imgp->object != NULL) 894 vm_object_deallocate(imgp->object); 895 896 free(imgp->freepath, M_TEMP); 897 898 if (error == 0) { 899 PROC_LOCK(p); 900 td->td_dbgflags |= TDB_EXEC; 901 PROC_UNLOCK(p); 902 903 /* 904 * Stop the process here if its stop event mask has 905 * the S_EXEC bit set. 906 */ 907 STOPEVENT(p, S_EXEC, 0); 908 goto done2; 909 } 910 911 exec_fail: 912 /* we're done here, clear P_INEXEC */ 913 PROC_LOCK(p); 914 p->p_flag &= ~P_INEXEC; 915 PROC_UNLOCK(p); 916 917 SDT_PROBE(proc, kernel, , exec__failure, error, 0, 0, 0, 0); 918 919 done2: 920 #ifdef MAC 921 mac_execve_exit(imgp); 922 mac_execve_interpreter_exit(interpvplabel); 923 #endif 924 exec_free_args(args); 925 926 if (error && imgp->vmspace_destroyed) { 927 /* sorry, no more process anymore. exit gracefully */ 928 exit1(td, W_EXITCODE(0, SIGABRT)); 929 /* NOT REACHED */ 930 } 931 932 #ifdef KTRACE 933 if (error == 0) 934 ktrprocctor(p); 935 #endif 936 937 return (error); 938 } 939 940 int 941 exec_map_first_page(imgp) 942 struct image_params *imgp; 943 { 944 int rv, i; 945 int initial_pagein; 946 vm_page_t ma[VM_INITIAL_PAGEIN]; 947 vm_object_t object; 948 949 if (imgp->firstpage != NULL) 950 exec_unmap_first_page(imgp); 951 952 object = imgp->vp->v_object; 953 if (object == NULL) 954 return (EACCES); 955 VM_OBJECT_WLOCK(object); 956 #if VM_NRESERVLEVEL > 0 957 if ((object->flags & OBJ_COLORED) == 0) { 958 object->flags |= OBJ_COLORED; 959 object->pg_color = 0; 960 } 961 #endif 962 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL); 963 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 964 initial_pagein = VM_INITIAL_PAGEIN; 965 if (initial_pagein > object->size) 966 initial_pagein = object->size; 967 for (i = 1; i < initial_pagein; i++) { 968 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 969 if (ma[i]->valid) 970 break; 971 if (vm_page_tryxbusy(ma[i])) 972 break; 973 } else { 974 ma[i] = vm_page_alloc(object, i, 975 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 976 if (ma[i] == NULL) 977 break; 978 } 979 } 980 initial_pagein = i; 981 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 982 ma[0] = vm_page_lookup(object, 0); 983 if ((rv != VM_PAGER_OK) || (ma[0] == NULL)) { 984 if (ma[0] != NULL) { 985 vm_page_lock(ma[0]); 986 vm_page_free(ma[0]); 987 vm_page_unlock(ma[0]); 988 } 989 VM_OBJECT_WUNLOCK(object); 990 return (EIO); 991 } 992 } 993 vm_page_xunbusy(ma[0]); 994 vm_page_lock(ma[0]); 995 vm_page_hold(ma[0]); 996 vm_page_unlock(ma[0]); 997 VM_OBJECT_WUNLOCK(object); 998 999 imgp->firstpage = sf_buf_alloc(ma[0], 0); 1000 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 1001 1002 return (0); 1003 } 1004 1005 void 1006 exec_unmap_first_page(imgp) 1007 struct image_params *imgp; 1008 { 1009 vm_page_t m; 1010 1011 if (imgp->firstpage != NULL) { 1012 m = sf_buf_page(imgp->firstpage); 1013 sf_buf_free(imgp->firstpage); 1014 imgp->firstpage = NULL; 1015 vm_page_lock(m); 1016 vm_page_unhold(m); 1017 vm_page_unlock(m); 1018 } 1019 } 1020 1021 /* 1022 * Destroy old address space, and allocate a new stack 1023 * The new stack is only SGROWSIZ large because it is grown 1024 * automatically in trap.c. 1025 */ 1026 int 1027 exec_new_vmspace(imgp, sv) 1028 struct image_params *imgp; 1029 struct sysentvec *sv; 1030 { 1031 int error; 1032 struct proc *p = imgp->proc; 1033 struct vmspace *vmspace = p->p_vmspace; 1034 vm_object_t obj; 1035 vm_offset_t sv_minuser, stack_addr; 1036 vm_map_t map; 1037 u_long ssiz; 1038 1039 imgp->vmspace_destroyed = 1; 1040 imgp->sysent = sv; 1041 1042 /* May be called with Giant held */ 1043 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1044 1045 /* 1046 * Blow away entire process VM, if address space not shared, 1047 * otherwise, create a new VM space so that other threads are 1048 * not disrupted 1049 */ 1050 map = &vmspace->vm_map; 1051 if (map_at_zero) 1052 sv_minuser = sv->sv_minuser; 1053 else 1054 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1055 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1056 vm_map_max(map) == sv->sv_maxuser) { 1057 shmexit(vmspace); 1058 pmap_remove_pages(vmspace_pmap(vmspace)); 1059 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1060 } else { 1061 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1062 if (error) 1063 return (error); 1064 vmspace = p->p_vmspace; 1065 map = &vmspace->vm_map; 1066 } 1067 1068 /* Map a shared page */ 1069 obj = sv->sv_shared_page_obj; 1070 if (obj != NULL) { 1071 vm_object_reference(obj); 1072 error = vm_map_fixed(map, obj, 0, 1073 sv->sv_shared_page_base, sv->sv_shared_page_len, 1074 VM_PROT_READ | VM_PROT_EXECUTE, 1075 VM_PROT_READ | VM_PROT_EXECUTE, 1076 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1077 if (error) { 1078 vm_object_deallocate(obj); 1079 return (error); 1080 } 1081 } 1082 1083 /* Allocate a new stack */ 1084 if (sv->sv_maxssiz != NULL) 1085 ssiz = *sv->sv_maxssiz; 1086 else 1087 ssiz = maxssiz; 1088 stack_addr = sv->sv_usrstack - ssiz; 1089 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1090 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1091 sv->sv_stackprot, 1092 VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1093 if (error) 1094 return (error); 1095 1096 /* 1097 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they 1098 * are still used to enforce the stack rlimit on the process stack. 1099 */ 1100 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1101 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1102 1103 return (0); 1104 } 1105 1106 /* 1107 * Copy out argument and environment strings from the old process address 1108 * space into the temporary string buffer. 1109 */ 1110 int 1111 exec_copyin_args(struct image_args *args, char *fname, 1112 enum uio_seg segflg, char **argv, char **envv) 1113 { 1114 char *argp, *envp; 1115 int error; 1116 size_t length; 1117 1118 bzero(args, sizeof(*args)); 1119 if (argv == NULL) 1120 return (EFAULT); 1121 1122 /* 1123 * Allocate demand-paged memory for the file name, argument, and 1124 * environment strings. 1125 */ 1126 error = exec_alloc_args(args); 1127 if (error != 0) 1128 return (error); 1129 1130 /* 1131 * Copy the file name. 1132 */ 1133 if (fname != NULL) { 1134 args->fname = args->buf; 1135 error = (segflg == UIO_SYSSPACE) ? 1136 copystr(fname, args->fname, PATH_MAX, &length) : 1137 copyinstr(fname, args->fname, PATH_MAX, &length); 1138 if (error != 0) 1139 goto err_exit; 1140 } else 1141 length = 0; 1142 1143 args->begin_argv = args->buf + length; 1144 args->endp = args->begin_argv; 1145 args->stringspace = ARG_MAX; 1146 1147 /* 1148 * extract arguments first 1149 */ 1150 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 1151 if (argp == (caddr_t) -1) { 1152 error = EFAULT; 1153 goto err_exit; 1154 } 1155 if ((error = copyinstr(argp, args->endp, 1156 args->stringspace, &length))) { 1157 if (error == ENAMETOOLONG) 1158 error = E2BIG; 1159 goto err_exit; 1160 } 1161 args->stringspace -= length; 1162 args->endp += length; 1163 args->argc++; 1164 } 1165 1166 args->begin_envv = args->endp; 1167 1168 /* 1169 * extract environment strings 1170 */ 1171 if (envv) { 1172 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) { 1173 if (envp == (caddr_t)-1) { 1174 error = EFAULT; 1175 goto err_exit; 1176 } 1177 if ((error = copyinstr(envp, args->endp, 1178 args->stringspace, &length))) { 1179 if (error == ENAMETOOLONG) 1180 error = E2BIG; 1181 goto err_exit; 1182 } 1183 args->stringspace -= length; 1184 args->endp += length; 1185 args->envc++; 1186 } 1187 } 1188 1189 return (0); 1190 1191 err_exit: 1192 exec_free_args(args); 1193 return (error); 1194 } 1195 1196 /* 1197 * Allocate temporary demand-paged, zero-filled memory for the file name, 1198 * argument, and environment strings. Returns zero if the allocation succeeds 1199 * and ENOMEM otherwise. 1200 */ 1201 int 1202 exec_alloc_args(struct image_args *args) 1203 { 1204 1205 args->buf = (char *)kmap_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 1206 return (args->buf != NULL ? 0 : ENOMEM); 1207 } 1208 1209 void 1210 exec_free_args(struct image_args *args) 1211 { 1212 1213 if (args->buf != NULL) { 1214 kmap_free_wakeup(exec_map, (vm_offset_t)args->buf, 1215 PATH_MAX + ARG_MAX); 1216 args->buf = NULL; 1217 } 1218 if (args->fname_buf != NULL) { 1219 free(args->fname_buf, M_TEMP); 1220 args->fname_buf = NULL; 1221 } 1222 } 1223 1224 /* 1225 * Copy strings out to the new process address space, constructing new arg 1226 * and env vector tables. Return a pointer to the base so that it can be used 1227 * as the initial stack pointer. 1228 */ 1229 register_t * 1230 exec_copyout_strings(imgp) 1231 struct image_params *imgp; 1232 { 1233 int argc, envc; 1234 char **vectp; 1235 char *stringp; 1236 uintptr_t destp; 1237 register_t *stack_base; 1238 struct ps_strings *arginfo; 1239 struct proc *p; 1240 size_t execpath_len; 1241 int szsigcode, szps; 1242 char canary[sizeof(long) * 8]; 1243 1244 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1245 /* 1246 * Calculate string base and vector table pointers. 1247 * Also deal with signal trampoline code for this exec type. 1248 */ 1249 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1250 execpath_len = strlen(imgp->execpath) + 1; 1251 else 1252 execpath_len = 0; 1253 p = imgp->proc; 1254 szsigcode = 0; 1255 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1256 if (p->p_sysent->sv_sigcode_base == 0) { 1257 if (p->p_sysent->sv_szsigcode != NULL) 1258 szsigcode = *(p->p_sysent->sv_szsigcode); 1259 } 1260 destp = (uintptr_t)arginfo; 1261 1262 /* 1263 * install sigcode 1264 */ 1265 if (szsigcode != 0) { 1266 destp -= szsigcode; 1267 destp = rounddown2(destp, sizeof(void *)); 1268 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode); 1269 } 1270 1271 /* 1272 * Copy the image path for the rtld. 1273 */ 1274 if (execpath_len != 0) { 1275 destp -= execpath_len; 1276 imgp->execpathp = destp; 1277 copyout(imgp->execpath, (void *)destp, execpath_len); 1278 } 1279 1280 /* 1281 * Prepare the canary for SSP. 1282 */ 1283 arc4rand(canary, sizeof(canary), 0); 1284 destp -= sizeof(canary); 1285 imgp->canary = destp; 1286 copyout(canary, (void *)destp, sizeof(canary)); 1287 imgp->canarylen = sizeof(canary); 1288 1289 /* 1290 * Prepare the pagesizes array. 1291 */ 1292 destp -= szps; 1293 destp = rounddown2(destp, sizeof(void *)); 1294 imgp->pagesizes = destp; 1295 copyout(pagesizes, (void *)destp, szps); 1296 imgp->pagesizeslen = szps; 1297 1298 destp -= ARG_MAX - imgp->args->stringspace; 1299 destp = rounddown2(destp, sizeof(void *)); 1300 1301 /* 1302 * If we have a valid auxargs ptr, prepare some room 1303 * on the stack. 1304 */ 1305 if (imgp->auxargs) { 1306 /* 1307 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1308 * lower compatibility. 1309 */ 1310 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1311 (AT_COUNT * 2); 1312 /* 1313 * The '+ 2' is for the null pointers at the end of each of 1314 * the arg and env vector sets,and imgp->auxarg_size is room 1315 * for argument of Runtime loader. 1316 */ 1317 vectp = (char **)(destp - (imgp->args->argc + 1318 imgp->args->envc + 2 + imgp->auxarg_size) 1319 * sizeof(char *)); 1320 } else { 1321 /* 1322 * The '+ 2' is for the null pointers at the end of each of 1323 * the arg and env vector sets 1324 */ 1325 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc 1326 + 2) * sizeof(char *)); 1327 } 1328 1329 /* 1330 * vectp also becomes our initial stack base 1331 */ 1332 stack_base = (register_t *)vectp; 1333 1334 stringp = imgp->args->begin_argv; 1335 argc = imgp->args->argc; 1336 envc = imgp->args->envc; 1337 1338 /* 1339 * Copy out strings - arguments and environment. 1340 */ 1341 copyout(stringp, (void *)destp, ARG_MAX - imgp->args->stringspace); 1342 1343 /* 1344 * Fill in "ps_strings" struct for ps, w, etc. 1345 */ 1346 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1347 suword32(&arginfo->ps_nargvstr, argc); 1348 1349 /* 1350 * Fill in argument portion of vector table. 1351 */ 1352 for (; argc > 0; --argc) { 1353 suword(vectp++, (long)(intptr_t)destp); 1354 while (*stringp++ != 0) 1355 destp++; 1356 destp++; 1357 } 1358 1359 /* a null vector table pointer separates the argp's from the envp's */ 1360 suword(vectp++, 0); 1361 1362 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1363 suword32(&arginfo->ps_nenvstr, envc); 1364 1365 /* 1366 * Fill in environment portion of vector table. 1367 */ 1368 for (; envc > 0; --envc) { 1369 suword(vectp++, (long)(intptr_t)destp); 1370 while (*stringp++ != 0) 1371 destp++; 1372 destp++; 1373 } 1374 1375 /* end of vector table is a null pointer */ 1376 suword(vectp, 0); 1377 1378 return (stack_base); 1379 } 1380 1381 /* 1382 * Check permissions of file to execute. 1383 * Called with imgp->vp locked. 1384 * Return 0 for success or error code on failure. 1385 */ 1386 int 1387 exec_check_permissions(imgp) 1388 struct image_params *imgp; 1389 { 1390 struct vnode *vp = imgp->vp; 1391 struct vattr *attr = imgp->attr; 1392 struct thread *td; 1393 int error, writecount; 1394 1395 td = curthread; 1396 1397 /* Get file attributes */ 1398 error = VOP_GETATTR(vp, attr, td->td_ucred); 1399 if (error) 1400 return (error); 1401 1402 #ifdef MAC 1403 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1404 if (error) 1405 return (error); 1406 #endif 1407 1408 /* 1409 * 1) Check if file execution is disabled for the filesystem that 1410 * this file resides on. 1411 * 2) Ensure that at least one execute bit is on. Otherwise, a 1412 * privileged user will always succeed, and we don't want this 1413 * to happen unless the file really is executable. 1414 * 3) Ensure that the file is a regular file. 1415 */ 1416 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1417 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1418 (attr->va_type != VREG)) 1419 return (EACCES); 1420 1421 /* 1422 * Zero length files can't be exec'd 1423 */ 1424 if (attr->va_size == 0) 1425 return (ENOEXEC); 1426 1427 /* 1428 * Check for execute permission to file based on current credentials. 1429 */ 1430 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1431 if (error) 1432 return (error); 1433 1434 /* 1435 * Check number of open-for-writes on the file and deny execution 1436 * if there are any. 1437 */ 1438 error = VOP_GET_WRITECOUNT(vp, &writecount); 1439 if (error != 0) 1440 return (error); 1441 if (writecount != 0) 1442 return (ETXTBSY); 1443 1444 /* 1445 * Call filesystem specific open routine (which does nothing in the 1446 * general case). 1447 */ 1448 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1449 if (error == 0) 1450 imgp->opened = 1; 1451 return (error); 1452 } 1453 1454 /* 1455 * Exec handler registration 1456 */ 1457 int 1458 exec_register(execsw_arg) 1459 const struct execsw *execsw_arg; 1460 { 1461 const struct execsw **es, **xs, **newexecsw; 1462 int count = 2; /* New slot and trailing NULL */ 1463 1464 if (execsw) 1465 for (es = execsw; *es; es++) 1466 count++; 1467 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1468 if (newexecsw == NULL) 1469 return (ENOMEM); 1470 xs = newexecsw; 1471 if (execsw) 1472 for (es = execsw; *es; es++) 1473 *xs++ = *es; 1474 *xs++ = execsw_arg; 1475 *xs = NULL; 1476 if (execsw) 1477 free(execsw, M_TEMP); 1478 execsw = newexecsw; 1479 return (0); 1480 } 1481 1482 int 1483 exec_unregister(execsw_arg) 1484 const struct execsw *execsw_arg; 1485 { 1486 const struct execsw **es, **xs, **newexecsw; 1487 int count = 1; 1488 1489 if (execsw == NULL) 1490 panic("unregister with no handlers left?\n"); 1491 1492 for (es = execsw; *es; es++) { 1493 if (*es == execsw_arg) 1494 break; 1495 } 1496 if (*es == NULL) 1497 return (ENOENT); 1498 for (es = execsw; *es; es++) 1499 if (*es != execsw_arg) 1500 count++; 1501 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1502 if (newexecsw == NULL) 1503 return (ENOMEM); 1504 xs = newexecsw; 1505 for (es = execsw; *es; es++) 1506 if (*es != execsw_arg) 1507 *xs++ = *es; 1508 *xs = NULL; 1509 if (execsw) 1510 free(execsw, M_TEMP); 1511 execsw = newexecsw; 1512 return (0); 1513 } 1514