1 /*- 2 * Copyright (c) 1993, David Greenman 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 #include "opt_capsicum.h" 31 #include "opt_hwpmc_hooks.h" 32 #include "opt_kdtrace.h" 33 #include "opt_ktrace.h" 34 #include "opt_vm.h" 35 36 #include <sys/param.h> 37 #include <sys/capability.h> 38 #include <sys/systm.h> 39 #include <sys/capability.h> 40 #include <sys/eventhandler.h> 41 #include <sys/lock.h> 42 #include <sys/mutex.h> 43 #include <sys/sysproto.h> 44 #include <sys/signalvar.h> 45 #include <sys/kernel.h> 46 #include <sys/mount.h> 47 #include <sys/filedesc.h> 48 #include <sys/fcntl.h> 49 #include <sys/acct.h> 50 #include <sys/exec.h> 51 #include <sys/imgact.h> 52 #include <sys/imgact_elf.h> 53 #include <sys/wait.h> 54 #include <sys/malloc.h> 55 #include <sys/priv.h> 56 #include <sys/proc.h> 57 #include <sys/pioctl.h> 58 #include <sys/namei.h> 59 #include <sys/resourcevar.h> 60 #include <sys/rwlock.h> 61 #include <sys/sched.h> 62 #include <sys/sdt.h> 63 #include <sys/sf_buf.h> 64 #include <sys/syscallsubr.h> 65 #include <sys/sysent.h> 66 #include <sys/shm.h> 67 #include <sys/sysctl.h> 68 #include <sys/vnode.h> 69 #include <sys/stat.h> 70 #ifdef KTRACE 71 #include <sys/ktrace.h> 72 #endif 73 74 #include <vm/vm.h> 75 #include <vm/vm_param.h> 76 #include <vm/pmap.h> 77 #include <vm/vm_page.h> 78 #include <vm/vm_map.h> 79 #include <vm/vm_kern.h> 80 #include <vm/vm_extern.h> 81 #include <vm/vm_object.h> 82 #include <vm/vm_pager.h> 83 84 #ifdef HWPMC_HOOKS 85 #include <sys/pmckern.h> 86 #endif 87 88 #include <machine/reg.h> 89 90 #include <security/audit/audit.h> 91 #include <security/mac/mac_framework.h> 92 93 #ifdef KDTRACE_HOOKS 94 #include <sys/dtrace_bsd.h> 95 dtrace_execexit_func_t dtrace_fasttrap_exec; 96 #endif 97 98 SDT_PROVIDER_DECLARE(proc); 99 SDT_PROBE_DEFINE1(proc, kernel, , exec, exec, "char *"); 100 SDT_PROBE_DEFINE1(proc, kernel, , exec_failure, exec-failure, "int"); 101 SDT_PROBE_DEFINE1(proc, kernel, , exec_success, exec-success, "char *"); 102 103 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 104 105 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 106 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 107 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 108 static int do_execve(struct thread *td, struct image_args *args, 109 struct mac *mac_p); 110 111 /* XXX This should be vm_size_t. */ 112 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD, 113 NULL, 0, sysctl_kern_ps_strings, "LU", ""); 114 115 /* XXX This should be vm_size_t. */ 116 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 117 CTLFLAG_CAPRD, NULL, 0, sysctl_kern_usrstack, "LU", ""); 118 119 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 120 NULL, 0, sysctl_kern_stackprot, "I", ""); 121 122 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 123 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 124 &ps_arg_cache_limit, 0, ""); 125 126 static int disallow_high_osrel; 127 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW, 128 &disallow_high_osrel, 0, 129 "Disallow execution of binaries built for higher version of the world"); 130 131 static int map_at_zero = 0; 132 TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero); 133 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &map_at_zero, 0, 134 "Permit processes to map an object at virtual address 0."); 135 136 static int 137 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 138 { 139 struct proc *p; 140 int error; 141 142 p = curproc; 143 #ifdef SCTL_MASK32 144 if (req->flags & SCTL_MASK32) { 145 unsigned int val; 146 val = (unsigned int)p->p_sysent->sv_psstrings; 147 error = SYSCTL_OUT(req, &val, sizeof(val)); 148 } else 149 #endif 150 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 151 sizeof(p->p_sysent->sv_psstrings)); 152 return error; 153 } 154 155 static int 156 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 157 { 158 struct proc *p; 159 int error; 160 161 p = curproc; 162 #ifdef SCTL_MASK32 163 if (req->flags & SCTL_MASK32) { 164 unsigned int val; 165 val = (unsigned int)p->p_sysent->sv_usrstack; 166 error = SYSCTL_OUT(req, &val, sizeof(val)); 167 } else 168 #endif 169 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 170 sizeof(p->p_sysent->sv_usrstack)); 171 return error; 172 } 173 174 static int 175 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 176 { 177 struct proc *p; 178 179 p = curproc; 180 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 181 sizeof(p->p_sysent->sv_stackprot))); 182 } 183 184 /* 185 * Each of the items is a pointer to a `const struct execsw', hence the 186 * double pointer here. 187 */ 188 static const struct execsw **execsw; 189 190 #ifndef _SYS_SYSPROTO_H_ 191 struct execve_args { 192 char *fname; 193 char **argv; 194 char **envv; 195 }; 196 #endif 197 198 int 199 sys_execve(td, uap) 200 struct thread *td; 201 struct execve_args /* { 202 char *fname; 203 char **argv; 204 char **envv; 205 } */ *uap; 206 { 207 int error; 208 struct image_args args; 209 210 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 211 uap->argv, uap->envv); 212 if (error == 0) 213 error = kern_execve(td, &args, NULL); 214 return (error); 215 } 216 217 #ifndef _SYS_SYSPROTO_H_ 218 struct fexecve_args { 219 int fd; 220 char **argv; 221 char **envv; 222 } 223 #endif 224 int 225 sys_fexecve(struct thread *td, struct fexecve_args *uap) 226 { 227 int error; 228 struct image_args args; 229 230 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 231 uap->argv, uap->envv); 232 if (error == 0) { 233 args.fd = uap->fd; 234 error = kern_execve(td, &args, NULL); 235 } 236 return (error); 237 } 238 239 #ifndef _SYS_SYSPROTO_H_ 240 struct __mac_execve_args { 241 char *fname; 242 char **argv; 243 char **envv; 244 struct mac *mac_p; 245 }; 246 #endif 247 248 int 249 sys___mac_execve(td, uap) 250 struct thread *td; 251 struct __mac_execve_args /* { 252 char *fname; 253 char **argv; 254 char **envv; 255 struct mac *mac_p; 256 } */ *uap; 257 { 258 #ifdef MAC 259 int error; 260 struct image_args args; 261 262 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 263 uap->argv, uap->envv); 264 if (error == 0) 265 error = kern_execve(td, &args, uap->mac_p); 266 return (error); 267 #else 268 return (ENOSYS); 269 #endif 270 } 271 272 /* 273 * XXX: kern_execve has the astonishing property of not always returning to 274 * the caller. If sufficiently bad things happen during the call to 275 * do_execve(), it can end up calling exit1(); as a result, callers must 276 * avoid doing anything which they might need to undo (e.g., allocating 277 * memory). 278 */ 279 int 280 kern_execve(td, args, mac_p) 281 struct thread *td; 282 struct image_args *args; 283 struct mac *mac_p; 284 { 285 struct proc *p = td->td_proc; 286 int error; 287 288 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 289 args->begin_envv - args->begin_argv); 290 AUDIT_ARG_ENVV(args->begin_envv, args->envc, 291 args->endp - args->begin_envv); 292 if (p->p_flag & P_HADTHREADS) { 293 PROC_LOCK(p); 294 if (thread_single(SINGLE_BOUNDARY)) { 295 PROC_UNLOCK(p); 296 exec_free_args(args); 297 return (ERESTART); /* Try again later. */ 298 } 299 PROC_UNLOCK(p); 300 } 301 302 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 } 316 317 return (error); 318 } 319 320 /* 321 * In-kernel implementation of execve(). All arguments are assumed to be 322 * userspace pointers from the passed thread. 323 */ 324 static int 325 do_execve(td, args, mac_p) 326 struct thread *td; 327 struct image_args *args; 328 struct mac *mac_p; 329 { 330 struct proc *p = td->td_proc; 331 struct nameidata nd; 332 struct ucred *newcred = NULL, *oldcred; 333 struct uidinfo *euip; 334 register_t *stack_base; 335 int error, i; 336 struct image_params image_params, *imgp; 337 struct vattr attr; 338 int (*img_first)(struct image_params *); 339 struct pargs *oldargs = NULL, *newargs = NULL; 340 struct sigacts *oldsigacts, *newsigacts; 341 #ifdef KTRACE 342 struct vnode *tracevp = NULL; 343 struct ucred *tracecred = NULL; 344 #endif 345 struct vnode *textvp = NULL, *binvp = NULL; 346 cap_rights_t rights; 347 int credential_changing; 348 int textset; 349 #ifdef MAC 350 struct label *interpvplabel = NULL; 351 int will_transition; 352 #endif 353 #ifdef HWPMC_HOOKS 354 struct pmckern_procexec pe; 355 #endif 356 static const char fexecv_proc_title[] = "(fexecv)"; 357 358 imgp = &image_params; 359 360 /* 361 * Lock the process and set the P_INEXEC flag to indicate that 362 * it should be left alone until we're done here. This is 363 * necessary to avoid race conditions - e.g. in ptrace() - 364 * that might allow a local user to illicitly obtain elevated 365 * privileges. 366 */ 367 PROC_LOCK(p); 368 KASSERT((p->p_flag & P_INEXEC) == 0, 369 ("%s(): process already has P_INEXEC flag", __func__)); 370 p->p_flag |= P_INEXEC; 371 PROC_UNLOCK(p); 372 373 /* 374 * Initialize part of the common data 375 */ 376 imgp->proc = p; 377 imgp->execlabel = NULL; 378 imgp->attr = &attr; 379 imgp->entry_addr = 0; 380 imgp->reloc_base = 0; 381 imgp->vmspace_destroyed = 0; 382 imgp->interpreted = 0; 383 imgp->opened = 0; 384 imgp->interpreter_name = NULL; 385 imgp->auxargs = NULL; 386 imgp->vp = NULL; 387 imgp->object = NULL; 388 imgp->firstpage = NULL; 389 imgp->ps_strings = 0; 390 imgp->auxarg_size = 0; 391 imgp->args = args; 392 imgp->execpath = imgp->freepath = NULL; 393 imgp->execpathp = 0; 394 imgp->canary = 0; 395 imgp->canarylen = 0; 396 imgp->pagesizes = 0; 397 imgp->pagesizeslen = 0; 398 imgp->stack_prot = 0; 399 400 #ifdef MAC 401 error = mac_execve_enter(imgp, mac_p); 402 if (error) 403 goto exec_fail; 404 #endif 405 406 imgp->image_header = NULL; 407 408 /* 409 * Translate the file name. namei() returns a vnode pointer 410 * in ni_vp amoung other things. 411 * 412 * XXXAUDIT: It would be desirable to also audit the name of the 413 * interpreter if this is an interpreted binary. 414 */ 415 if (args->fname != NULL) { 416 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 417 | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 418 } 419 420 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 421 422 interpret: 423 if (args->fname != NULL) { 424 #ifdef CAPABILITY_MODE 425 /* 426 * While capability mode can't reach this point via direct 427 * path arguments to execve(), we also don't allow 428 * interpreters to be used in capability mode (for now). 429 * Catch indirect lookups and return a permissions error. 430 */ 431 if (IN_CAPABILITY_MODE(td)) { 432 error = ECAPMODE; 433 goto exec_fail; 434 } 435 #endif 436 error = namei(&nd); 437 if (error) 438 goto exec_fail; 439 440 binvp = nd.ni_vp; 441 imgp->vp = binvp; 442 } else { 443 AUDIT_ARG_FD(args->fd); 444 /* 445 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 446 */ 447 error = fgetvp_exec(td, args->fd, 448 cap_rights_init(&rights, CAP_FEXECVE), &binvp); 449 if (error) 450 goto exec_fail; 451 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY); 452 AUDIT_ARG_VNODE1(binvp); 453 imgp->vp = binvp; 454 } 455 456 /* 457 * Check file permissions (also 'opens' file) 458 */ 459 error = exec_check_permissions(imgp); 460 if (error) 461 goto exec_fail_dealloc; 462 463 imgp->object = imgp->vp->v_object; 464 if (imgp->object != NULL) 465 vm_object_reference(imgp->object); 466 467 /* 468 * Set VV_TEXT now so no one can write to the executable while we're 469 * activating it. 470 * 471 * Remember if this was set before and unset it in case this is not 472 * actually an executable image. 473 */ 474 textset = VOP_IS_TEXT(imgp->vp); 475 VOP_SET_TEXT(imgp->vp); 476 477 error = exec_map_first_page(imgp); 478 if (error) 479 goto exec_fail_dealloc; 480 481 imgp->proc->p_osrel = 0; 482 /* 483 * If the current process has a special image activator it 484 * wants to try first, call it. For example, emulating shell 485 * scripts differently. 486 */ 487 error = -1; 488 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 489 error = img_first(imgp); 490 491 /* 492 * Loop through the list of image activators, calling each one. 493 * An activator returns -1 if there is no match, 0 on success, 494 * and an error otherwise. 495 */ 496 for (i = 0; error == -1 && execsw[i]; ++i) { 497 if (execsw[i]->ex_imgact == NULL || 498 execsw[i]->ex_imgact == img_first) { 499 continue; 500 } 501 error = (*execsw[i]->ex_imgact)(imgp); 502 } 503 504 if (error) { 505 if (error == -1) { 506 if (textset == 0) 507 VOP_UNSET_TEXT(imgp->vp); 508 error = ENOEXEC; 509 } 510 goto exec_fail_dealloc; 511 } 512 513 /* 514 * Special interpreter operation, cleanup and loop up to try to 515 * activate the interpreter. 516 */ 517 if (imgp->interpreted) { 518 exec_unmap_first_page(imgp); 519 /* 520 * VV_TEXT needs to be unset for scripts. There is a short 521 * period before we determine that something is a script where 522 * VV_TEXT will be set. The vnode lock is held over this 523 * entire period so nothing should illegitimately be blocked. 524 */ 525 VOP_UNSET_TEXT(imgp->vp); 526 /* free name buffer and old vnode */ 527 if (args->fname != NULL) 528 NDFREE(&nd, NDF_ONLY_PNBUF); 529 #ifdef MAC 530 mac_execve_interpreter_enter(binvp, &interpvplabel); 531 #endif 532 if (imgp->opened) { 533 VOP_CLOSE(binvp, FREAD, td->td_ucred, td); 534 imgp->opened = 0; 535 } 536 vput(binvp); 537 vm_object_deallocate(imgp->object); 538 imgp->object = NULL; 539 /* set new name to that of the interpreter */ 540 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 541 UIO_SYSSPACE, imgp->interpreter_name, td); 542 args->fname = imgp->interpreter_name; 543 goto interpret; 544 } 545 546 /* 547 * NB: We unlock the vnode here because it is believed that none 548 * of the sv_copyout_strings/sv_fixup operations require the vnode. 549 */ 550 VOP_UNLOCK(imgp->vp, 0); 551 552 /* 553 * Do the best to calculate the full path to the image file. 554 */ 555 if (imgp->auxargs != NULL && 556 ((args->fname != NULL && args->fname[0] == '/') || 557 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0)) 558 imgp->execpath = args->fname; 559 560 if (disallow_high_osrel && 561 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 562 error = ENOEXEC; 563 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 564 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 565 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 566 goto exec_fail_dealloc; 567 } 568 569 /* 570 * Copy out strings (args and env) and initialize stack base 571 */ 572 if (p->p_sysent->sv_copyout_strings) 573 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 574 else 575 stack_base = exec_copyout_strings(imgp); 576 577 /* 578 * If custom stack fixup routine present for this process 579 * let it do the stack setup. 580 * Else stuff argument count as first item on stack 581 */ 582 if (p->p_sysent->sv_fixup != NULL) 583 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 584 else 585 suword(--stack_base, imgp->args->argc); 586 587 /* 588 * For security and other reasons, the file descriptor table cannot 589 * be shared after an exec. 590 */ 591 fdunshare(p, td); 592 593 /* 594 * Malloc things before we need locks. 595 */ 596 newcred = crget(); 597 euip = uifind(attr.va_uid); 598 i = imgp->args->begin_envv - imgp->args->begin_argv; 599 /* Cache arguments if they fit inside our allowance */ 600 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 601 newargs = pargs_alloc(i); 602 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 603 } 604 605 /* close files on exec */ 606 fdcloseexec(td); 607 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 608 609 /* Get a reference to the vnode prior to locking the proc */ 610 VREF(binvp); 611 612 /* 613 * For security and other reasons, signal handlers cannot 614 * be shared after an exec. The new process gets a copy of the old 615 * handlers. In execsigs(), the new process will have its signals 616 * reset. 617 */ 618 PROC_LOCK(p); 619 oldcred = crcopysafe(p, newcred); 620 if (sigacts_shared(p->p_sigacts)) { 621 oldsigacts = p->p_sigacts; 622 PROC_UNLOCK(p); 623 newsigacts = sigacts_alloc(); 624 sigacts_copy(newsigacts, oldsigacts); 625 PROC_LOCK(p); 626 p->p_sigacts = newsigacts; 627 } else 628 oldsigacts = NULL; 629 630 /* Stop profiling */ 631 stopprofclock(p); 632 633 /* reset caught signals */ 634 execsigs(p); 635 636 /* name this process - nameiexec(p, ndp) */ 637 bzero(p->p_comm, sizeof(p->p_comm)); 638 if (args->fname) 639 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 640 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 641 else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0) 642 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 643 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 644 #ifdef KTR 645 sched_clear_tdname(td); 646 #endif 647 648 /* 649 * mark as execed, wakeup the process that vforked (if any) and tell 650 * it that it now has its own resources back 651 */ 652 p->p_flag |= P_EXEC; 653 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 654 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 655 cv_broadcast(&p->p_pwait); 656 } 657 658 /* 659 * Implement image setuid/setgid. 660 * 661 * Don't honor setuid/setgid if the filesystem prohibits it or if 662 * the process is being traced. 663 * 664 * We disable setuid/setgid/etc in compatibility mode on the basis 665 * that most setugid applications are not written with that 666 * environment in mind, and will therefore almost certainly operate 667 * incorrectly. In principle there's no reason that setugid 668 * applications might not be useful in capability mode, so we may want 669 * to reconsider this conservative design choice in the future. 670 * 671 * XXXMAC: For the time being, use NOSUID to also prohibit 672 * transitions on the file system. 673 */ 674 credential_changing = 0; 675 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 676 attr.va_uid; 677 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 678 attr.va_gid; 679 #ifdef MAC 680 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 681 interpvplabel, imgp); 682 credential_changing |= will_transition; 683 #endif 684 685 if (credential_changing && 686 #ifdef CAPABILITY_MODE 687 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 688 #endif 689 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 690 (p->p_flag & P_TRACED) == 0) { 691 /* 692 * Turn off syscall tracing for set-id programs, except for 693 * root. Record any set-id flags first to make sure that 694 * we do not regain any tracing during a possible block. 695 */ 696 setsugid(p); 697 698 #ifdef KTRACE 699 if (p->p_tracecred != NULL && 700 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0)) 701 ktrprocexec(p, &tracecred, &tracevp); 702 #endif 703 /* 704 * Close any file descriptors 0..2 that reference procfs, 705 * then make sure file descriptors 0..2 are in use. 706 * 707 * setugidsafety() may call closef() and then pfind() 708 * which may grab the process lock. 709 * fdcheckstd() may call falloc() which may block to 710 * allocate memory, so temporarily drop the process lock. 711 */ 712 PROC_UNLOCK(p); 713 VOP_UNLOCK(imgp->vp, 0); 714 setugidsafety(td); 715 error = fdcheckstd(td); 716 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 717 if (error != 0) 718 goto done1; 719 PROC_LOCK(p); 720 /* 721 * Set the new credentials. 722 */ 723 if (attr.va_mode & S_ISUID) 724 change_euid(newcred, euip); 725 if (attr.va_mode & S_ISGID) 726 change_egid(newcred, attr.va_gid); 727 #ifdef MAC 728 if (will_transition) { 729 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 730 interpvplabel, imgp); 731 } 732 #endif 733 /* 734 * Implement correct POSIX saved-id behavior. 735 * 736 * XXXMAC: Note that the current logic will save the 737 * uid and gid if a MAC domain transition occurs, even 738 * though maybe it shouldn't. 739 */ 740 change_svuid(newcred, newcred->cr_uid); 741 change_svgid(newcred, newcred->cr_gid); 742 p->p_ucred = newcred; 743 newcred = NULL; 744 } else { 745 if (oldcred->cr_uid == oldcred->cr_ruid && 746 oldcred->cr_gid == oldcred->cr_rgid) 747 p->p_flag &= ~P_SUGID; 748 /* 749 * Implement correct POSIX saved-id behavior. 750 * 751 * XXX: It's not clear that the existing behavior is 752 * POSIX-compliant. A number of sources indicate that the 753 * saved uid/gid should only be updated if the new ruid is 754 * not equal to the old ruid, or the new euid is not equal 755 * to the old euid and the new euid is not equal to the old 756 * ruid. The FreeBSD code always updates the saved uid/gid. 757 * Also, this code uses the new (replaced) euid and egid as 758 * the source, which may or may not be the right ones to use. 759 */ 760 if (oldcred->cr_svuid != oldcred->cr_uid || 761 oldcred->cr_svgid != oldcred->cr_gid) { 762 change_svuid(newcred, newcred->cr_uid); 763 change_svgid(newcred, newcred->cr_gid); 764 p->p_ucred = newcred; 765 newcred = NULL; 766 } 767 } 768 769 /* 770 * Store the vp for use in procfs. This vnode was referenced prior 771 * to locking the proc lock. 772 */ 773 textvp = p->p_textvp; 774 p->p_textvp = binvp; 775 776 #ifdef KDTRACE_HOOKS 777 /* 778 * Tell the DTrace fasttrap provider about the exec if it 779 * has declared an interest. 780 */ 781 if (dtrace_fasttrap_exec) 782 dtrace_fasttrap_exec(p); 783 #endif 784 785 /* 786 * Notify others that we exec'd, and clear the P_INEXEC flag 787 * as we're now a bona fide freshly-execed process. 788 */ 789 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 790 p->p_flag &= ~P_INEXEC; 791 792 /* clear "fork but no exec" flag, as we _are_ execing */ 793 p->p_acflag &= ~AFORK; 794 795 /* 796 * Free any previous argument cache and replace it with 797 * the new argument cache, if any. 798 */ 799 oldargs = p->p_args; 800 p->p_args = newargs; 801 newargs = NULL; 802 803 #ifdef HWPMC_HOOKS 804 /* 805 * Check if system-wide sampling is in effect or if the 806 * current process is using PMCs. If so, do exec() time 807 * processing. This processing needs to happen AFTER the 808 * P_INEXEC flag is cleared. 809 * 810 * The proc lock needs to be released before taking the PMC 811 * SX. 812 */ 813 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 814 PROC_UNLOCK(p); 815 VOP_UNLOCK(imgp->vp, 0); 816 pe.pm_credentialschanged = credential_changing; 817 pe.pm_entryaddr = imgp->entry_addr; 818 819 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 820 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 821 } else 822 PROC_UNLOCK(p); 823 #else /* !HWPMC_HOOKS */ 824 PROC_UNLOCK(p); 825 #endif 826 827 /* Set values passed into the program in registers. */ 828 if (p->p_sysent->sv_setregs) 829 (*p->p_sysent->sv_setregs)(td, imgp, 830 (u_long)(uintptr_t)stack_base); 831 else 832 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 833 834 vfs_mark_atime(imgp->vp, td->td_ucred); 835 836 SDT_PROBE(proc, kernel, , exec_success, args->fname, 0, 0, 0, 0); 837 838 done1: 839 /* 840 * Free any resources malloc'd earlier that we didn't use. 841 */ 842 uifree(euip); 843 if (newcred == NULL) 844 crfree(oldcred); 845 else 846 crfree(newcred); 847 VOP_UNLOCK(imgp->vp, 0); 848 849 /* 850 * Handle deferred decrement of ref counts. 851 */ 852 if (textvp != NULL) 853 vrele(textvp); 854 if (binvp && error != 0) 855 vrele(binvp); 856 #ifdef KTRACE 857 if (tracevp != NULL) 858 vrele(tracevp); 859 if (tracecred != NULL) 860 crfree(tracecred); 861 #endif 862 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 863 pargs_drop(oldargs); 864 pargs_drop(newargs); 865 if (oldsigacts != NULL) 866 sigacts_free(oldsigacts); 867 868 exec_fail_dealloc: 869 870 /* 871 * free various allocated resources 872 */ 873 if (imgp->firstpage != NULL) 874 exec_unmap_first_page(imgp); 875 876 if (imgp->vp != NULL) { 877 if (args->fname) 878 NDFREE(&nd, NDF_ONLY_PNBUF); 879 if (imgp->opened) 880 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 881 vput(imgp->vp); 882 } 883 884 if (imgp->object != NULL) 885 vm_object_deallocate(imgp->object); 886 887 free(imgp->freepath, M_TEMP); 888 889 if (error == 0) { 890 PROC_LOCK(p); 891 td->td_dbgflags |= TDB_EXEC; 892 PROC_UNLOCK(p); 893 894 /* 895 * Stop the process here if its stop event mask has 896 * the S_EXEC bit set. 897 */ 898 STOPEVENT(p, S_EXEC, 0); 899 goto done2; 900 } 901 902 exec_fail: 903 /* we're done here, clear P_INEXEC */ 904 PROC_LOCK(p); 905 p->p_flag &= ~P_INEXEC; 906 PROC_UNLOCK(p); 907 908 SDT_PROBE(proc, kernel, , exec_failure, error, 0, 0, 0, 0); 909 910 done2: 911 #ifdef MAC 912 mac_execve_exit(imgp); 913 mac_execve_interpreter_exit(interpvplabel); 914 #endif 915 exec_free_args(args); 916 917 if (error && imgp->vmspace_destroyed) { 918 /* sorry, no more process anymore. exit gracefully */ 919 exit1(td, W_EXITCODE(0, SIGABRT)); 920 /* NOT REACHED */ 921 } 922 923 #ifdef KTRACE 924 if (error == 0) 925 ktrprocctor(p); 926 #endif 927 928 return (error); 929 } 930 931 int 932 exec_map_first_page(imgp) 933 struct image_params *imgp; 934 { 935 int rv, i; 936 int initial_pagein; 937 vm_page_t ma[VM_INITIAL_PAGEIN]; 938 vm_object_t object; 939 940 if (imgp->firstpage != NULL) 941 exec_unmap_first_page(imgp); 942 943 object = imgp->vp->v_object; 944 if (object == NULL) 945 return (EACCES); 946 VM_OBJECT_WLOCK(object); 947 #if VM_NRESERVLEVEL > 0 948 if ((object->flags & OBJ_COLORED) == 0) { 949 object->flags |= OBJ_COLORED; 950 object->pg_color = 0; 951 } 952 #endif 953 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL); 954 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 955 initial_pagein = VM_INITIAL_PAGEIN; 956 if (initial_pagein > object->size) 957 initial_pagein = object->size; 958 for (i = 1; i < initial_pagein; i++) { 959 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 960 if (ma[i]->valid) 961 break; 962 if (vm_page_tryxbusy(ma[i])) 963 break; 964 } else { 965 ma[i] = vm_page_alloc(object, i, 966 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 967 if (ma[i] == NULL) 968 break; 969 } 970 } 971 initial_pagein = i; 972 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 973 ma[0] = vm_page_lookup(object, 0); 974 if ((rv != VM_PAGER_OK) || (ma[0] == NULL)) { 975 if (ma[0] != NULL) { 976 vm_page_lock(ma[0]); 977 vm_page_free(ma[0]); 978 vm_page_unlock(ma[0]); 979 } 980 VM_OBJECT_WUNLOCK(object); 981 return (EIO); 982 } 983 } 984 vm_page_xunbusy(ma[0]); 985 vm_page_lock(ma[0]); 986 vm_page_hold(ma[0]); 987 vm_page_unlock(ma[0]); 988 VM_OBJECT_WUNLOCK(object); 989 990 imgp->firstpage = sf_buf_alloc(ma[0], 0); 991 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 992 993 return (0); 994 } 995 996 void 997 exec_unmap_first_page(imgp) 998 struct image_params *imgp; 999 { 1000 vm_page_t m; 1001 1002 if (imgp->firstpage != NULL) { 1003 m = sf_buf_page(imgp->firstpage); 1004 sf_buf_free(imgp->firstpage); 1005 imgp->firstpage = NULL; 1006 vm_page_lock(m); 1007 vm_page_unhold(m); 1008 vm_page_unlock(m); 1009 } 1010 } 1011 1012 /* 1013 * Destroy old address space, and allocate a new stack 1014 * The new stack is only SGROWSIZ large because it is grown 1015 * automatically in trap.c. 1016 */ 1017 int 1018 exec_new_vmspace(imgp, sv) 1019 struct image_params *imgp; 1020 struct sysentvec *sv; 1021 { 1022 int error; 1023 struct proc *p = imgp->proc; 1024 struct vmspace *vmspace = p->p_vmspace; 1025 vm_object_t obj; 1026 vm_offset_t sv_minuser, stack_addr; 1027 vm_map_t map; 1028 u_long ssiz; 1029 1030 imgp->vmspace_destroyed = 1; 1031 imgp->sysent = sv; 1032 1033 /* May be called with Giant held */ 1034 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1035 1036 /* 1037 * Blow away entire process VM, if address space not shared, 1038 * otherwise, create a new VM space so that other threads are 1039 * not disrupted 1040 */ 1041 map = &vmspace->vm_map; 1042 if (map_at_zero) 1043 sv_minuser = sv->sv_minuser; 1044 else 1045 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1046 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1047 vm_map_max(map) == sv->sv_maxuser) { 1048 shmexit(vmspace); 1049 pmap_remove_pages(vmspace_pmap(vmspace)); 1050 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1051 } else { 1052 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1053 if (error) 1054 return (error); 1055 vmspace = p->p_vmspace; 1056 map = &vmspace->vm_map; 1057 } 1058 1059 /* Map a shared page */ 1060 obj = sv->sv_shared_page_obj; 1061 if (obj != NULL) { 1062 vm_object_reference(obj); 1063 error = vm_map_fixed(map, obj, 0, 1064 sv->sv_shared_page_base, sv->sv_shared_page_len, 1065 VM_PROT_READ | VM_PROT_EXECUTE, 1066 VM_PROT_READ | VM_PROT_EXECUTE, 1067 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1068 if (error) { 1069 vm_object_deallocate(obj); 1070 return (error); 1071 } 1072 } 1073 1074 /* Allocate a new stack */ 1075 if (sv->sv_maxssiz != NULL) 1076 ssiz = *sv->sv_maxssiz; 1077 else 1078 ssiz = maxssiz; 1079 stack_addr = sv->sv_usrstack - ssiz; 1080 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1081 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1082 sv->sv_stackprot, 1083 VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1084 if (error) 1085 return (error); 1086 1087 #ifdef __ia64__ 1088 /* Allocate a new register stack */ 1089 stack_addr = IA64_BACKINGSTORE; 1090 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1091 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP); 1092 if (error) 1093 return (error); 1094 #endif 1095 1096 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 1097 * VM_STACK case, but they are still used to monitor the size of the 1098 * process stack so we can check the stack rlimit. 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, *destp; 1236 register_t *stack_base; 1237 struct ps_strings *arginfo; 1238 struct proc *p; 1239 size_t execpath_len; 1240 int szsigcode, szps; 1241 char canary[sizeof(long) * 8]; 1242 1243 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1244 /* 1245 * Calculate string base and vector table pointers. 1246 * Also deal with signal trampoline code for this exec type. 1247 */ 1248 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1249 execpath_len = strlen(imgp->execpath) + 1; 1250 else 1251 execpath_len = 0; 1252 p = imgp->proc; 1253 szsigcode = 0; 1254 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1255 if (p->p_sysent->sv_sigcode_base == 0) { 1256 if (p->p_sysent->sv_szsigcode != NULL) 1257 szsigcode = *(p->p_sysent->sv_szsigcode); 1258 } 1259 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 1260 roundup(execpath_len, sizeof(char *)) - 1261 roundup(sizeof(canary), sizeof(char *)) - 1262 roundup(szps, sizeof(char *)) - 1263 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *)); 1264 1265 /* 1266 * install sigcode 1267 */ 1268 if (szsigcode != 0) 1269 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo - 1270 szsigcode), szsigcode); 1271 1272 /* 1273 * Copy the image path for the rtld. 1274 */ 1275 if (execpath_len != 0) { 1276 imgp->execpathp = (uintptr_t)arginfo - szsigcode - execpath_len; 1277 copyout(imgp->execpath, (void *)imgp->execpathp, 1278 execpath_len); 1279 } 1280 1281 /* 1282 * Prepare the canary for SSP. 1283 */ 1284 arc4rand(canary, sizeof(canary), 0); 1285 imgp->canary = (uintptr_t)arginfo - szsigcode - execpath_len - 1286 sizeof(canary); 1287 copyout(canary, (void *)imgp->canary, sizeof(canary)); 1288 imgp->canarylen = sizeof(canary); 1289 1290 /* 1291 * Prepare the pagesizes array. 1292 */ 1293 imgp->pagesizes = (uintptr_t)arginfo - szsigcode - execpath_len - 1294 roundup(sizeof(canary), sizeof(char *)) - szps; 1295 copyout(pagesizes, (void *)imgp->pagesizes, szps); 1296 imgp->pagesizeslen = szps; 1297 1298 /* 1299 * If we have a valid auxargs ptr, prepare some room 1300 * on the stack. 1301 */ 1302 if (imgp->auxargs) { 1303 /* 1304 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1305 * lower compatibility. 1306 */ 1307 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1308 (AT_COUNT * 2); 1309 /* 1310 * The '+ 2' is for the null pointers at the end of each of 1311 * the arg and env vector sets,and imgp->auxarg_size is room 1312 * for argument of Runtime loader. 1313 */ 1314 vectp = (char **)(destp - (imgp->args->argc + 1315 imgp->args->envc + 2 + imgp->auxarg_size) 1316 * sizeof(char *)); 1317 } else { 1318 /* 1319 * The '+ 2' is for the null pointers at the end of each of 1320 * the arg and env vector sets 1321 */ 1322 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) * 1323 sizeof(char *)); 1324 } 1325 1326 /* 1327 * vectp also becomes our initial stack base 1328 */ 1329 stack_base = (register_t *)vectp; 1330 1331 stringp = imgp->args->begin_argv; 1332 argc = imgp->args->argc; 1333 envc = imgp->args->envc; 1334 1335 /* 1336 * Copy out strings - arguments and environment. 1337 */ 1338 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace); 1339 1340 /* 1341 * Fill in "ps_strings" struct for ps, w, etc. 1342 */ 1343 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1344 suword32(&arginfo->ps_nargvstr, argc); 1345 1346 /* 1347 * Fill in argument portion of vector table. 1348 */ 1349 for (; argc > 0; --argc) { 1350 suword(vectp++, (long)(intptr_t)destp); 1351 while (*stringp++ != 0) 1352 destp++; 1353 destp++; 1354 } 1355 1356 /* a null vector table pointer separates the argp's from the envp's */ 1357 suword(vectp++, 0); 1358 1359 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1360 suword32(&arginfo->ps_nenvstr, envc); 1361 1362 /* 1363 * Fill in environment portion of vector table. 1364 */ 1365 for (; envc > 0; --envc) { 1366 suword(vectp++, (long)(intptr_t)destp); 1367 while (*stringp++ != 0) 1368 destp++; 1369 destp++; 1370 } 1371 1372 /* end of vector table is a null pointer */ 1373 suword(vectp, 0); 1374 1375 return (stack_base); 1376 } 1377 1378 /* 1379 * Check permissions of file to execute. 1380 * Called with imgp->vp locked. 1381 * Return 0 for success or error code on failure. 1382 */ 1383 int 1384 exec_check_permissions(imgp) 1385 struct image_params *imgp; 1386 { 1387 struct vnode *vp = imgp->vp; 1388 struct vattr *attr = imgp->attr; 1389 struct thread *td; 1390 int error, writecount; 1391 1392 td = curthread; 1393 1394 /* Get file attributes */ 1395 error = VOP_GETATTR(vp, attr, td->td_ucred); 1396 if (error) 1397 return (error); 1398 1399 #ifdef MAC 1400 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1401 if (error) 1402 return (error); 1403 #endif 1404 1405 /* 1406 * 1) Check if file execution is disabled for the filesystem that 1407 * this file resides on. 1408 * 2) Ensure that at least one execute bit is on. Otherwise, a 1409 * privileged user will always succeed, and we don't want this 1410 * to happen unless the file really is executable. 1411 * 3) Ensure that the file is a regular file. 1412 */ 1413 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1414 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1415 (attr->va_type != VREG)) 1416 return (EACCES); 1417 1418 /* 1419 * Zero length files can't be exec'd 1420 */ 1421 if (attr->va_size == 0) 1422 return (ENOEXEC); 1423 1424 /* 1425 * Check for execute permission to file based on current credentials. 1426 */ 1427 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1428 if (error) 1429 return (error); 1430 1431 /* 1432 * Check number of open-for-writes on the file and deny execution 1433 * if there are any. 1434 */ 1435 error = VOP_GET_WRITECOUNT(vp, &writecount); 1436 if (error != 0) 1437 return (error); 1438 if (writecount != 0) 1439 return (ETXTBSY); 1440 1441 /* 1442 * Call filesystem specific open routine (which does nothing in the 1443 * general case). 1444 */ 1445 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1446 if (error == 0) 1447 imgp->opened = 1; 1448 return (error); 1449 } 1450 1451 /* 1452 * Exec handler registration 1453 */ 1454 int 1455 exec_register(execsw_arg) 1456 const struct execsw *execsw_arg; 1457 { 1458 const struct execsw **es, **xs, **newexecsw; 1459 int count = 2; /* New slot and trailing NULL */ 1460 1461 if (execsw) 1462 for (es = execsw; *es; es++) 1463 count++; 1464 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1465 if (newexecsw == NULL) 1466 return (ENOMEM); 1467 xs = newexecsw; 1468 if (execsw) 1469 for (es = execsw; *es; es++) 1470 *xs++ = *es; 1471 *xs++ = execsw_arg; 1472 *xs = NULL; 1473 if (execsw) 1474 free(execsw, M_TEMP); 1475 execsw = newexecsw; 1476 return (0); 1477 } 1478 1479 int 1480 exec_unregister(execsw_arg) 1481 const struct execsw *execsw_arg; 1482 { 1483 const struct execsw **es, **xs, **newexecsw; 1484 int count = 1; 1485 1486 if (execsw == NULL) 1487 panic("unregister with no handlers left?\n"); 1488 1489 for (es = execsw; *es; es++) { 1490 if (*es == execsw_arg) 1491 break; 1492 } 1493 if (*es == NULL) 1494 return (ENOENT); 1495 for (es = execsw; *es; es++) 1496 if (*es != execsw_arg) 1497 count++; 1498 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1499 if (newexecsw == NULL) 1500 return (ENOMEM); 1501 xs = newexecsw; 1502 for (es = execsw; *es; es++) 1503 if (*es != execsw_arg) 1504 *xs++ = *es; 1505 *xs = NULL; 1506 if (execsw) 1507 free(execsw, M_TEMP); 1508 execsw = newexecsw; 1509 return (0); 1510 } 1511