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(p, 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(p, SINGLE_EXIT); 312 else 313 thread_single_end(p, SINGLE_BOUNDARY); 314 PROC_UNLOCK(p); 315 } 316 if ((td->td_pflags & TDP_EXECVMSPC) != 0) { 317 KASSERT(td->td_proc->p_vmspace != oldvmspace, 318 ("oldvmspace still used")); 319 vmspace_free(oldvmspace); 320 td->td_pflags &= ~TDP_EXECVMSPC; 321 } 322 323 return (error); 324 } 325 326 /* 327 * In-kernel implementation of execve(). All arguments are assumed to be 328 * userspace pointers from the passed thread. 329 */ 330 static int 331 do_execve(td, args, mac_p) 332 struct thread *td; 333 struct image_args *args; 334 struct mac *mac_p; 335 { 336 struct proc *p = td->td_proc; 337 struct nameidata nd; 338 struct ucred *newcred = NULL, *oldcred; 339 struct uidinfo *euip = NULL; 340 register_t *stack_base; 341 int error, i; 342 struct image_params image_params, *imgp; 343 struct vattr attr; 344 int (*img_first)(struct image_params *); 345 struct pargs *oldargs = NULL, *newargs = NULL; 346 struct sigacts *oldsigacts, *newsigacts; 347 #ifdef KTRACE 348 struct vnode *tracevp = NULL; 349 struct ucred *tracecred = NULL; 350 #endif 351 struct vnode *textvp = NULL, *binvp; 352 cap_rights_t rights; 353 int credential_changing; 354 int textset; 355 #ifdef MAC 356 struct label *interpvplabel = NULL; 357 int will_transition; 358 #endif 359 #ifdef HWPMC_HOOKS 360 struct pmckern_procexec pe; 361 #endif 362 static const char fexecv_proc_title[] = "(fexecv)"; 363 364 imgp = &image_params; 365 366 /* 367 * Lock the process and set the P_INEXEC flag to indicate that 368 * it should be left alone until we're done here. This is 369 * necessary to avoid race conditions - e.g. in ptrace() - 370 * that might allow a local user to illicitly obtain elevated 371 * privileges. 372 */ 373 PROC_LOCK(p); 374 KASSERT((p->p_flag & P_INEXEC) == 0, 375 ("%s(): process already has P_INEXEC flag", __func__)); 376 p->p_flag |= P_INEXEC; 377 PROC_UNLOCK(p); 378 379 /* 380 * Initialize part of the common data 381 */ 382 bzero(imgp, sizeof(*imgp)); 383 imgp->proc = p; 384 imgp->attr = &attr; 385 imgp->args = args; 386 387 #ifdef MAC 388 error = mac_execve_enter(imgp, mac_p); 389 if (error) 390 goto exec_fail; 391 #endif 392 393 /* 394 * Translate the file name. namei() returns a vnode pointer 395 * in ni_vp amoung other things. 396 * 397 * XXXAUDIT: It would be desirable to also audit the name of the 398 * interpreter if this is an interpreted binary. 399 */ 400 if (args->fname != NULL) { 401 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 402 | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 403 } 404 405 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 406 407 interpret: 408 if (args->fname != NULL) { 409 #ifdef CAPABILITY_MODE 410 /* 411 * While capability mode can't reach this point via direct 412 * path arguments to execve(), we also don't allow 413 * interpreters to be used in capability mode (for now). 414 * Catch indirect lookups and return a permissions error. 415 */ 416 if (IN_CAPABILITY_MODE(td)) { 417 error = ECAPMODE; 418 goto exec_fail; 419 } 420 #endif 421 error = namei(&nd); 422 if (error) 423 goto exec_fail; 424 425 binvp = nd.ni_vp; 426 imgp->vp = binvp; 427 } else { 428 AUDIT_ARG_FD(args->fd); 429 /* 430 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 431 */ 432 error = fgetvp_exec(td, args->fd, 433 cap_rights_init(&rights, CAP_FEXECVE), &binvp); 434 if (error) 435 goto exec_fail; 436 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY); 437 AUDIT_ARG_VNODE1(binvp); 438 imgp->vp = binvp; 439 } 440 441 /* 442 * Check file permissions (also 'opens' file) 443 */ 444 error = exec_check_permissions(imgp); 445 if (error) 446 goto exec_fail_dealloc; 447 448 imgp->object = imgp->vp->v_object; 449 if (imgp->object != NULL) 450 vm_object_reference(imgp->object); 451 452 /* 453 * Set VV_TEXT now so no one can write to the executable while we're 454 * activating it. 455 * 456 * Remember if this was set before and unset it in case this is not 457 * actually an executable image. 458 */ 459 textset = VOP_IS_TEXT(imgp->vp); 460 VOP_SET_TEXT(imgp->vp); 461 462 error = exec_map_first_page(imgp); 463 if (error) 464 goto exec_fail_dealloc; 465 466 imgp->proc->p_osrel = 0; 467 /* 468 * If the current process has a special image activator it 469 * wants to try first, call it. For example, emulating shell 470 * scripts differently. 471 */ 472 error = -1; 473 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 474 error = img_first(imgp); 475 476 /* 477 * Loop through the list of image activators, calling each one. 478 * An activator returns -1 if there is no match, 0 on success, 479 * and an error otherwise. 480 */ 481 for (i = 0; error == -1 && execsw[i]; ++i) { 482 if (execsw[i]->ex_imgact == NULL || 483 execsw[i]->ex_imgact == img_first) { 484 continue; 485 } 486 error = (*execsw[i]->ex_imgact)(imgp); 487 } 488 489 if (error) { 490 if (error == -1) { 491 if (textset == 0) 492 VOP_UNSET_TEXT(imgp->vp); 493 error = ENOEXEC; 494 } 495 goto exec_fail_dealloc; 496 } 497 498 /* 499 * Special interpreter operation, cleanup and loop up to try to 500 * activate the interpreter. 501 */ 502 if (imgp->interpreted) { 503 exec_unmap_first_page(imgp); 504 /* 505 * VV_TEXT needs to be unset for scripts. There is a short 506 * period before we determine that something is a script where 507 * VV_TEXT will be set. The vnode lock is held over this 508 * entire period so nothing should illegitimately be blocked. 509 */ 510 VOP_UNSET_TEXT(imgp->vp); 511 /* free name buffer and old vnode */ 512 if (args->fname != NULL) 513 NDFREE(&nd, NDF_ONLY_PNBUF); 514 #ifdef MAC 515 mac_execve_interpreter_enter(binvp, &interpvplabel); 516 #endif 517 if (imgp->opened) { 518 VOP_CLOSE(binvp, FREAD, td->td_ucred, td); 519 imgp->opened = 0; 520 } 521 vput(binvp); 522 vm_object_deallocate(imgp->object); 523 imgp->object = NULL; 524 /* set new name to that of the interpreter */ 525 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 526 UIO_SYSSPACE, imgp->interpreter_name, td); 527 args->fname = imgp->interpreter_name; 528 goto interpret; 529 } 530 531 /* 532 * NB: We unlock the vnode here because it is believed that none 533 * of the sv_copyout_strings/sv_fixup operations require the vnode. 534 */ 535 VOP_UNLOCK(imgp->vp, 0); 536 537 /* 538 * Do the best to calculate the full path to the image file. 539 */ 540 if (imgp->auxargs != NULL && 541 ((args->fname != NULL && args->fname[0] == '/') || 542 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0)) 543 imgp->execpath = args->fname; 544 545 if (disallow_high_osrel && 546 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 547 error = ENOEXEC; 548 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 549 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 550 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 551 goto exec_fail_dealloc; 552 } 553 554 /* 555 * Copy out strings (args and env) and initialize stack base 556 */ 557 if (p->p_sysent->sv_copyout_strings) 558 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 559 else 560 stack_base = exec_copyout_strings(imgp); 561 562 /* 563 * If custom stack fixup routine present for this process 564 * let it do the stack setup. 565 * Else stuff argument count as first item on stack 566 */ 567 if (p->p_sysent->sv_fixup != NULL) 568 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 569 else 570 suword(--stack_base, imgp->args->argc); 571 572 /* 573 * For security and other reasons, the file descriptor table cannot 574 * be shared after an exec. 575 */ 576 fdunshare(td); 577 /* close files on exec */ 578 fdcloseexec(td); 579 580 /* 581 * Malloc things before we need locks. 582 */ 583 i = imgp->args->begin_envv - imgp->args->begin_argv; 584 /* Cache arguments if they fit inside our allowance */ 585 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 586 newargs = pargs_alloc(i); 587 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 588 } 589 590 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 591 592 /* Get a reference to the vnode prior to locking the proc */ 593 VREF(binvp); 594 595 /* 596 * For security and other reasons, signal handlers cannot 597 * be shared after an exec. The new process gets a copy of the old 598 * handlers. In execsigs(), the new process will have its signals 599 * reset. 600 */ 601 if (sigacts_shared(p->p_sigacts)) { 602 oldsigacts = p->p_sigacts; 603 newsigacts = sigacts_alloc(); 604 sigacts_copy(newsigacts, oldsigacts); 605 } else { 606 oldsigacts = NULL; 607 newsigacts = NULL; /* satisfy gcc */ 608 } 609 610 PROC_LOCK(p); 611 if (oldsigacts) 612 p->p_sigacts = newsigacts; 613 oldcred = p->p_ucred; 614 /* Stop profiling */ 615 stopprofclock(p); 616 617 /* reset caught signals */ 618 execsigs(p); 619 620 /* name this process - nameiexec(p, ndp) */ 621 bzero(p->p_comm, sizeof(p->p_comm)); 622 if (args->fname) 623 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 624 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 625 else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0) 626 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 627 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 628 #ifdef KTR 629 sched_clear_tdname(td); 630 #endif 631 632 /* 633 * mark as execed, wakeup the process that vforked (if any) and tell 634 * it that it now has its own resources back 635 */ 636 p->p_flag |= P_EXEC; 637 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0) 638 p->p_flag2 &= ~P2_NOTRACE; 639 if (p->p_flag & P_PPWAIT) { 640 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 641 cv_broadcast(&p->p_pwait); 642 } 643 644 /* 645 * Implement image setuid/setgid. 646 * 647 * Don't honor setuid/setgid if the filesystem prohibits it or if 648 * the process is being traced. 649 * 650 * We disable setuid/setgid/etc in compatibility mode on the basis 651 * that most setugid applications are not written with that 652 * environment in mind, and will therefore almost certainly operate 653 * incorrectly. In principle there's no reason that setugid 654 * applications might not be useful in capability mode, so we may want 655 * to reconsider this conservative design choice in the future. 656 * 657 * XXXMAC: For the time being, use NOSUID to also prohibit 658 * transitions on the file system. 659 */ 660 credential_changing = 0; 661 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 662 attr.va_uid; 663 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 664 attr.va_gid; 665 #ifdef MAC 666 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 667 interpvplabel, imgp); 668 credential_changing |= will_transition; 669 #endif 670 671 if (credential_changing && 672 #ifdef CAPABILITY_MODE 673 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 674 #endif 675 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 676 (p->p_flag & P_TRACED) == 0) { 677 /* 678 * Turn off syscall tracing for set-id programs, except for 679 * root. Record any set-id flags first to make sure that 680 * we do not regain any tracing during a possible block. 681 */ 682 setsugid(p); 683 684 #ifdef KTRACE 685 if (p->p_tracecred != NULL && 686 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0)) 687 ktrprocexec(p, &tracecred, &tracevp); 688 #endif 689 /* 690 * Close any file descriptors 0..2 that reference procfs, 691 * then make sure file descriptors 0..2 are in use. 692 * 693 * Both fdsetugidsafety() and fdcheckstd() may call functions 694 * taking sleepable locks, so temporarily drop our locks. 695 */ 696 PROC_UNLOCK(p); 697 VOP_UNLOCK(imgp->vp, 0); 698 fdsetugidsafety(td); 699 error = fdcheckstd(td); 700 if (error != 0) 701 goto done1; 702 newcred = crdup(oldcred); 703 euip = uifind(attr.va_uid); 704 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 705 PROC_LOCK(p); 706 /* 707 * Set the new credentials. 708 */ 709 if (attr.va_mode & S_ISUID) 710 change_euid(newcred, euip); 711 if (attr.va_mode & S_ISGID) 712 change_egid(newcred, attr.va_gid); 713 #ifdef MAC 714 if (will_transition) { 715 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 716 interpvplabel, imgp); 717 } 718 #endif 719 /* 720 * Implement correct POSIX saved-id behavior. 721 * 722 * XXXMAC: Note that the current logic will save the 723 * uid and gid if a MAC domain transition occurs, even 724 * though maybe it shouldn't. 725 */ 726 change_svuid(newcred, newcred->cr_uid); 727 change_svgid(newcred, newcred->cr_gid); 728 proc_set_cred(p, newcred); 729 } else { 730 if (oldcred->cr_uid == oldcred->cr_ruid && 731 oldcred->cr_gid == oldcred->cr_rgid) 732 p->p_flag &= ~P_SUGID; 733 /* 734 * Implement correct POSIX saved-id behavior. 735 * 736 * XXX: It's not clear that the existing behavior is 737 * POSIX-compliant. A number of sources indicate that the 738 * saved uid/gid should only be updated if the new ruid is 739 * not equal to the old ruid, or the new euid is not equal 740 * to the old euid and the new euid is not equal to the old 741 * ruid. The FreeBSD code always updates the saved uid/gid. 742 * Also, this code uses the new (replaced) euid and egid as 743 * the source, which may or may not be the right ones to use. 744 */ 745 if (oldcred->cr_svuid != oldcred->cr_uid || 746 oldcred->cr_svgid != oldcred->cr_gid) { 747 PROC_UNLOCK(p); 748 VOP_UNLOCK(imgp->vp, 0); 749 newcred = crdup(oldcred); 750 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 751 PROC_LOCK(p); 752 change_svuid(newcred, newcred->cr_uid); 753 change_svgid(newcred, newcred->cr_gid); 754 proc_set_cred(p, newcred); 755 } 756 } 757 758 /* 759 * Store the vp for use in procfs. This vnode was referenced prior 760 * to locking the proc lock. 761 */ 762 textvp = p->p_textvp; 763 p->p_textvp = binvp; 764 765 #ifdef KDTRACE_HOOKS 766 /* 767 * Tell the DTrace fasttrap provider about the exec if it 768 * has declared an interest. 769 */ 770 if (dtrace_fasttrap_exec) 771 dtrace_fasttrap_exec(p); 772 #endif 773 774 /* 775 * Notify others that we exec'd, and clear the P_INEXEC flag 776 * as we're now a bona fide freshly-execed process. 777 */ 778 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 779 p->p_flag &= ~P_INEXEC; 780 781 /* clear "fork but no exec" flag, as we _are_ execing */ 782 p->p_acflag &= ~AFORK; 783 784 /* 785 * Free any previous argument cache and replace it with 786 * the new argument cache, if any. 787 */ 788 oldargs = p->p_args; 789 p->p_args = newargs; 790 newargs = NULL; 791 792 #ifdef HWPMC_HOOKS 793 /* 794 * Check if system-wide sampling is in effect or if the 795 * current process is using PMCs. If so, do exec() time 796 * processing. This processing needs to happen AFTER the 797 * P_INEXEC flag is cleared. 798 * 799 * The proc lock needs to be released before taking the PMC 800 * SX. 801 */ 802 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 803 PROC_UNLOCK(p); 804 VOP_UNLOCK(imgp->vp, 0); 805 pe.pm_credentialschanged = credential_changing; 806 pe.pm_entryaddr = imgp->entry_addr; 807 808 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 809 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 810 } else 811 PROC_UNLOCK(p); 812 #else /* !HWPMC_HOOKS */ 813 PROC_UNLOCK(p); 814 #endif 815 816 /* Set values passed into the program in registers. */ 817 if (p->p_sysent->sv_setregs) 818 (*p->p_sysent->sv_setregs)(td, imgp, 819 (u_long)(uintptr_t)stack_base); 820 else 821 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 822 823 vfs_mark_atime(imgp->vp, td->td_ucred); 824 825 SDT_PROBE(proc, kernel, , exec__success, args->fname, 0, 0, 0, 0); 826 827 VOP_UNLOCK(imgp->vp, 0); 828 done1: 829 /* 830 * Free any resources malloc'd earlier that we didn't use. 831 */ 832 if (euip != NULL) 833 uifree(euip); 834 if (newcred != NULL) 835 crfree(oldcred); 836 837 /* 838 * Handle deferred decrement of ref counts. 839 */ 840 if (textvp != NULL) 841 vrele(textvp); 842 if (error != 0) 843 vrele(binvp); 844 #ifdef KTRACE 845 if (tracevp != NULL) 846 vrele(tracevp); 847 if (tracecred != NULL) 848 crfree(tracecred); 849 #endif 850 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 851 pargs_drop(oldargs); 852 pargs_drop(newargs); 853 if (oldsigacts != NULL) 854 sigacts_free(oldsigacts); 855 856 exec_fail_dealloc: 857 858 /* 859 * free various allocated resources 860 */ 861 if (imgp->firstpage != NULL) 862 exec_unmap_first_page(imgp); 863 864 if (imgp->vp != NULL) { 865 if (args->fname) 866 NDFREE(&nd, NDF_ONLY_PNBUF); 867 if (imgp->opened) 868 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 869 vput(imgp->vp); 870 } 871 872 if (imgp->object != NULL) 873 vm_object_deallocate(imgp->object); 874 875 free(imgp->freepath, M_TEMP); 876 877 if (error == 0) { 878 PROC_LOCK(p); 879 td->td_dbgflags |= TDB_EXEC; 880 PROC_UNLOCK(p); 881 882 /* 883 * Stop the process here if its stop event mask has 884 * the S_EXEC bit set. 885 */ 886 STOPEVENT(p, S_EXEC, 0); 887 goto done2; 888 } 889 890 exec_fail: 891 /* we're done here, clear P_INEXEC */ 892 PROC_LOCK(p); 893 p->p_flag &= ~P_INEXEC; 894 PROC_UNLOCK(p); 895 896 SDT_PROBE(proc, kernel, , exec__failure, error, 0, 0, 0, 0); 897 898 done2: 899 #ifdef MAC 900 mac_execve_exit(imgp); 901 mac_execve_interpreter_exit(interpvplabel); 902 #endif 903 exec_free_args(args); 904 905 if (error && imgp->vmspace_destroyed) { 906 /* sorry, no more process anymore. exit gracefully */ 907 exit1(td, W_EXITCODE(0, SIGABRT)); 908 /* NOT REACHED */ 909 } 910 911 #ifdef KTRACE 912 if (error == 0) 913 ktrprocctor(p); 914 #endif 915 916 return (error); 917 } 918 919 int 920 exec_map_first_page(imgp) 921 struct image_params *imgp; 922 { 923 int rv, i; 924 int initial_pagein; 925 vm_page_t ma[VM_INITIAL_PAGEIN]; 926 vm_object_t object; 927 928 if (imgp->firstpage != NULL) 929 exec_unmap_first_page(imgp); 930 931 object = imgp->vp->v_object; 932 if (object == NULL) 933 return (EACCES); 934 VM_OBJECT_WLOCK(object); 935 #if VM_NRESERVLEVEL > 0 936 vm_object_color(object, 0); 937 #endif 938 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL); 939 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 940 initial_pagein = VM_INITIAL_PAGEIN; 941 if (initial_pagein > object->size) 942 initial_pagein = object->size; 943 for (i = 1; i < initial_pagein; i++) { 944 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 945 if (ma[i]->valid) 946 break; 947 if (vm_page_tryxbusy(ma[i])) 948 break; 949 } else { 950 ma[i] = vm_page_alloc(object, i, 951 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 952 if (ma[i] == NULL) 953 break; 954 } 955 } 956 initial_pagein = i; 957 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 958 ma[0] = vm_page_lookup(object, 0); 959 if ((rv != VM_PAGER_OK) || (ma[0] == NULL)) { 960 if (ma[0] != NULL) { 961 vm_page_lock(ma[0]); 962 vm_page_free(ma[0]); 963 vm_page_unlock(ma[0]); 964 } 965 VM_OBJECT_WUNLOCK(object); 966 return (EIO); 967 } 968 } 969 vm_page_xunbusy(ma[0]); 970 vm_page_lock(ma[0]); 971 vm_page_hold(ma[0]); 972 vm_page_activate(ma[0]); 973 vm_page_unlock(ma[0]); 974 VM_OBJECT_WUNLOCK(object); 975 976 imgp->firstpage = sf_buf_alloc(ma[0], 0); 977 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 978 979 return (0); 980 } 981 982 void 983 exec_unmap_first_page(imgp) 984 struct image_params *imgp; 985 { 986 vm_page_t m; 987 988 if (imgp->firstpage != NULL) { 989 m = sf_buf_page(imgp->firstpage); 990 sf_buf_free(imgp->firstpage); 991 imgp->firstpage = NULL; 992 vm_page_lock(m); 993 vm_page_unhold(m); 994 vm_page_unlock(m); 995 } 996 } 997 998 /* 999 * Destroy old address space, and allocate a new stack 1000 * The new stack is only SGROWSIZ large because it is grown 1001 * automatically in trap.c. 1002 */ 1003 int 1004 exec_new_vmspace(imgp, sv) 1005 struct image_params *imgp; 1006 struct sysentvec *sv; 1007 { 1008 int error; 1009 struct proc *p = imgp->proc; 1010 struct vmspace *vmspace = p->p_vmspace; 1011 vm_object_t obj; 1012 struct rlimit rlim_stack; 1013 vm_offset_t sv_minuser, stack_addr; 1014 vm_map_t map; 1015 u_long ssiz; 1016 1017 imgp->vmspace_destroyed = 1; 1018 imgp->sysent = sv; 1019 1020 /* May be called with Giant held */ 1021 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1022 1023 /* 1024 * Blow away entire process VM, if address space not shared, 1025 * otherwise, create a new VM space so that other threads are 1026 * not disrupted 1027 */ 1028 map = &vmspace->vm_map; 1029 if (map_at_zero) 1030 sv_minuser = sv->sv_minuser; 1031 else 1032 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1033 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1034 vm_map_max(map) == sv->sv_maxuser) { 1035 shmexit(vmspace); 1036 pmap_remove_pages(vmspace_pmap(vmspace)); 1037 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1038 } else { 1039 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1040 if (error) 1041 return (error); 1042 vmspace = p->p_vmspace; 1043 map = &vmspace->vm_map; 1044 } 1045 1046 /* Map a shared page */ 1047 obj = sv->sv_shared_page_obj; 1048 if (obj != NULL) { 1049 vm_object_reference(obj); 1050 error = vm_map_fixed(map, obj, 0, 1051 sv->sv_shared_page_base, sv->sv_shared_page_len, 1052 VM_PROT_READ | VM_PROT_EXECUTE, 1053 VM_PROT_READ | VM_PROT_EXECUTE, 1054 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1055 if (error) { 1056 vm_object_deallocate(obj); 1057 return (error); 1058 } 1059 } 1060 1061 /* Allocate a new stack */ 1062 if (imgp->stack_sz != 0) { 1063 ssiz = trunc_page(imgp->stack_sz); 1064 PROC_LOCK(p); 1065 lim_rlimit(p, RLIMIT_STACK, &rlim_stack); 1066 PROC_UNLOCK(p); 1067 if (ssiz > rlim_stack.rlim_max) 1068 ssiz = rlim_stack.rlim_max; 1069 if (ssiz > rlim_stack.rlim_cur) { 1070 rlim_stack.rlim_cur = ssiz; 1071 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack); 1072 } 1073 } else if (sv->sv_maxssiz != NULL) { 1074 ssiz = *sv->sv_maxssiz; 1075 } else { 1076 ssiz = maxssiz; 1077 } 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 /* 1087 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they 1088 * are still used to enforce the stack rlimit on the process stack. 1089 */ 1090 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1091 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1092 1093 return (0); 1094 } 1095 1096 /* 1097 * Copy out argument and environment strings from the old process address 1098 * space into the temporary string buffer. 1099 */ 1100 int 1101 exec_copyin_args(struct image_args *args, char *fname, 1102 enum uio_seg segflg, char **argv, char **envv) 1103 { 1104 u_long argp, envp; 1105 int error; 1106 size_t length; 1107 1108 bzero(args, sizeof(*args)); 1109 if (argv == NULL) 1110 return (EFAULT); 1111 1112 /* 1113 * Allocate demand-paged memory for the file name, argument, and 1114 * environment strings. 1115 */ 1116 error = exec_alloc_args(args); 1117 if (error != 0) 1118 return (error); 1119 1120 /* 1121 * Copy the file name. 1122 */ 1123 if (fname != NULL) { 1124 args->fname = args->buf; 1125 error = (segflg == UIO_SYSSPACE) ? 1126 copystr(fname, args->fname, PATH_MAX, &length) : 1127 copyinstr(fname, args->fname, PATH_MAX, &length); 1128 if (error != 0) 1129 goto err_exit; 1130 } else 1131 length = 0; 1132 1133 args->begin_argv = args->buf + length; 1134 args->endp = args->begin_argv; 1135 args->stringspace = ARG_MAX; 1136 1137 /* 1138 * extract arguments first 1139 */ 1140 for (;;) { 1141 error = fueword(argv++, &argp); 1142 if (error == -1) { 1143 error = EFAULT; 1144 goto err_exit; 1145 } 1146 if (argp == 0) 1147 break; 1148 error = copyinstr((void *)(uintptr_t)argp, args->endp, 1149 args->stringspace, &length); 1150 if (error != 0) { 1151 if (error == ENAMETOOLONG) 1152 error = E2BIG; 1153 goto err_exit; 1154 } 1155 args->stringspace -= length; 1156 args->endp += length; 1157 args->argc++; 1158 } 1159 1160 args->begin_envv = args->endp; 1161 1162 /* 1163 * extract environment strings 1164 */ 1165 if (envv) { 1166 for (;;) { 1167 error = fueword(envv++, &envp); 1168 if (error == -1) { 1169 error = EFAULT; 1170 goto err_exit; 1171 } 1172 if (envp == 0) 1173 break; 1174 error = copyinstr((void *)(uintptr_t)envp, 1175 args->endp, args->stringspace, &length); 1176 if (error != 0) { 1177 if (error == ENAMETOOLONG) 1178 error = E2BIG; 1179 goto err_exit; 1180 } 1181 args->stringspace -= length; 1182 args->endp += length; 1183 args->envc++; 1184 } 1185 } 1186 1187 return (0); 1188 1189 err_exit: 1190 exec_free_args(args); 1191 return (error); 1192 } 1193 1194 /* 1195 * Allocate temporary demand-paged, zero-filled memory for the file name, 1196 * argument, and environment strings. Returns zero if the allocation succeeds 1197 * and ENOMEM otherwise. 1198 */ 1199 int 1200 exec_alloc_args(struct image_args *args) 1201 { 1202 1203 args->buf = (char *)kmap_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 1204 return (args->buf != NULL ? 0 : ENOMEM); 1205 } 1206 1207 void 1208 exec_free_args(struct image_args *args) 1209 { 1210 1211 if (args->buf != NULL) { 1212 kmap_free_wakeup(exec_map, (vm_offset_t)args->buf, 1213 PATH_MAX + ARG_MAX); 1214 args->buf = NULL; 1215 } 1216 if (args->fname_buf != NULL) { 1217 free(args->fname_buf, M_TEMP); 1218 args->fname_buf = NULL; 1219 } 1220 } 1221 1222 /* 1223 * Copy strings out to the new process address space, constructing new arg 1224 * and env vector tables. Return a pointer to the base so that it can be used 1225 * as the initial stack pointer. 1226 */ 1227 register_t * 1228 exec_copyout_strings(imgp) 1229 struct image_params *imgp; 1230 { 1231 int argc, envc; 1232 char **vectp; 1233 char *stringp; 1234 uintptr_t 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 = (uintptr_t)arginfo; 1259 1260 /* 1261 * install sigcode 1262 */ 1263 if (szsigcode != 0) { 1264 destp -= szsigcode; 1265 destp = rounddown2(destp, sizeof(void *)); 1266 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode); 1267 } 1268 1269 /* 1270 * Copy the image path for the rtld. 1271 */ 1272 if (execpath_len != 0) { 1273 destp -= execpath_len; 1274 imgp->execpathp = destp; 1275 copyout(imgp->execpath, (void *)destp, execpath_len); 1276 } 1277 1278 /* 1279 * Prepare the canary for SSP. 1280 */ 1281 arc4rand(canary, sizeof(canary), 0); 1282 destp -= sizeof(canary); 1283 imgp->canary = destp; 1284 copyout(canary, (void *)destp, sizeof(canary)); 1285 imgp->canarylen = sizeof(canary); 1286 1287 /* 1288 * Prepare the pagesizes array. 1289 */ 1290 destp -= szps; 1291 destp = rounddown2(destp, sizeof(void *)); 1292 imgp->pagesizes = destp; 1293 copyout(pagesizes, (void *)destp, szps); 1294 imgp->pagesizeslen = szps; 1295 1296 destp -= ARG_MAX - imgp->args->stringspace; 1297 destp = rounddown2(destp, sizeof(void *)); 1298 1299 /* 1300 * If we have a valid auxargs ptr, prepare some room 1301 * on the stack. 1302 */ 1303 if (imgp->auxargs) { 1304 /* 1305 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1306 * lower compatibility. 1307 */ 1308 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1309 (AT_COUNT * 2); 1310 /* 1311 * The '+ 2' is for the null pointers at the end of each of 1312 * the arg and env vector sets,and imgp->auxarg_size is room 1313 * for argument of Runtime loader. 1314 */ 1315 vectp = (char **)(destp - (imgp->args->argc + 1316 imgp->args->envc + 2 + imgp->auxarg_size) 1317 * sizeof(char *)); 1318 } else { 1319 /* 1320 * The '+ 2' is for the null pointers at the end of each of 1321 * the arg and env vector sets 1322 */ 1323 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc 1324 + 2) * sizeof(char *)); 1325 } 1326 1327 /* 1328 * vectp also becomes our initial stack base 1329 */ 1330 stack_base = (register_t *)vectp; 1331 1332 stringp = imgp->args->begin_argv; 1333 argc = imgp->args->argc; 1334 envc = imgp->args->envc; 1335 1336 /* 1337 * Copy out strings - arguments and environment. 1338 */ 1339 copyout(stringp, (void *)destp, ARG_MAX - imgp->args->stringspace); 1340 1341 /* 1342 * Fill in "ps_strings" struct for ps, w, etc. 1343 */ 1344 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1345 suword32(&arginfo->ps_nargvstr, argc); 1346 1347 /* 1348 * Fill in argument portion of vector table. 1349 */ 1350 for (; argc > 0; --argc) { 1351 suword(vectp++, (long)(intptr_t)destp); 1352 while (*stringp++ != 0) 1353 destp++; 1354 destp++; 1355 } 1356 1357 /* a null vector table pointer separates the argp's from the envp's */ 1358 suword(vectp++, 0); 1359 1360 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1361 suword32(&arginfo->ps_nenvstr, envc); 1362 1363 /* 1364 * Fill in environment portion of vector table. 1365 */ 1366 for (; envc > 0; --envc) { 1367 suword(vectp++, (long)(intptr_t)destp); 1368 while (*stringp++ != 0) 1369 destp++; 1370 destp++; 1371 } 1372 1373 /* end of vector table is a null pointer */ 1374 suword(vectp, 0); 1375 1376 return (stack_base); 1377 } 1378 1379 /* 1380 * Check permissions of file to execute. 1381 * Called with imgp->vp locked. 1382 * Return 0 for success or error code on failure. 1383 */ 1384 int 1385 exec_check_permissions(imgp) 1386 struct image_params *imgp; 1387 { 1388 struct vnode *vp = imgp->vp; 1389 struct vattr *attr = imgp->attr; 1390 struct thread *td; 1391 int error, writecount; 1392 1393 td = curthread; 1394 1395 /* Get file attributes */ 1396 error = VOP_GETATTR(vp, attr, td->td_ucred); 1397 if (error) 1398 return (error); 1399 1400 #ifdef MAC 1401 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1402 if (error) 1403 return (error); 1404 #endif 1405 1406 /* 1407 * 1) Check if file execution is disabled for the filesystem that 1408 * this file resides on. 1409 * 2) Ensure that at least one execute bit is on. Otherwise, a 1410 * privileged user will always succeed, and we don't want this 1411 * to happen unless the file really is executable. 1412 * 3) Ensure that the file is a regular file. 1413 */ 1414 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1415 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1416 (attr->va_type != VREG)) 1417 return (EACCES); 1418 1419 /* 1420 * Zero length files can't be exec'd 1421 */ 1422 if (attr->va_size == 0) 1423 return (ENOEXEC); 1424 1425 /* 1426 * Check for execute permission to file based on current credentials. 1427 */ 1428 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1429 if (error) 1430 return (error); 1431 1432 /* 1433 * Check number of open-for-writes on the file and deny execution 1434 * if there are any. 1435 */ 1436 error = VOP_GET_WRITECOUNT(vp, &writecount); 1437 if (error != 0) 1438 return (error); 1439 if (writecount != 0) 1440 return (ETXTBSY); 1441 1442 /* 1443 * Call filesystem specific open routine (which does nothing in the 1444 * general case). 1445 */ 1446 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1447 if (error == 0) 1448 imgp->opened = 1; 1449 return (error); 1450 } 1451 1452 /* 1453 * Exec handler registration 1454 */ 1455 int 1456 exec_register(execsw_arg) 1457 const struct execsw *execsw_arg; 1458 { 1459 const struct execsw **es, **xs, **newexecsw; 1460 int count = 2; /* New slot and trailing NULL */ 1461 1462 if (execsw) 1463 for (es = execsw; *es; es++) 1464 count++; 1465 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1466 if (newexecsw == NULL) 1467 return (ENOMEM); 1468 xs = newexecsw; 1469 if (execsw) 1470 for (es = execsw; *es; es++) 1471 *xs++ = *es; 1472 *xs++ = execsw_arg; 1473 *xs = NULL; 1474 if (execsw) 1475 free(execsw, M_TEMP); 1476 execsw = newexecsw; 1477 return (0); 1478 } 1479 1480 int 1481 exec_unregister(execsw_arg) 1482 const struct execsw *execsw_arg; 1483 { 1484 const struct execsw **es, **xs, **newexecsw; 1485 int count = 1; 1486 1487 if (execsw == NULL) 1488 panic("unregister with no handlers left?\n"); 1489 1490 for (es = execsw; *es; es++) { 1491 if (*es == execsw_arg) 1492 break; 1493 } 1494 if (*es == NULL) 1495 return (ENOENT); 1496 for (es = execsw; *es; es++) 1497 if (*es != execsw_arg) 1498 count++; 1499 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1500 if (newexecsw == NULL) 1501 return (ENOMEM); 1502 xs = newexecsw; 1503 for (es = execsw; *es; es++) 1504 if (*es != execsw_arg) 1505 *xs++ = *es; 1506 *xs = NULL; 1507 if (execsw) 1508 free(execsw, M_TEMP); 1509 execsw = newexecsw; 1510 return (0); 1511 } 1512