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/sched.h> 61 #include <sys/sdt.h> 62 #include <sys/sf_buf.h> 63 #include <sys/syscallsubr.h> 64 #include <sys/sysent.h> 65 #include <sys/shm.h> 66 #include <sys/sysctl.h> 67 #include <sys/vnode.h> 68 #include <sys/stat.h> 69 #ifdef KTRACE 70 #include <sys/ktrace.h> 71 #endif 72 73 #include <vm/vm.h> 74 #include <vm/vm_param.h> 75 #include <vm/pmap.h> 76 #include <vm/vm_page.h> 77 #include <vm/vm_map.h> 78 #include <vm/vm_kern.h> 79 #include <vm/vm_extern.h> 80 #include <vm/vm_object.h> 81 #include <vm/vm_pager.h> 82 83 #ifdef HWPMC_HOOKS 84 #include <sys/pmckern.h> 85 #endif 86 87 #include <machine/reg.h> 88 89 #include <security/audit/audit.h> 90 #include <security/mac/mac_framework.h> 91 92 #ifdef KDTRACE_HOOKS 93 #include <sys/dtrace_bsd.h> 94 dtrace_execexit_func_t dtrace_fasttrap_exec; 95 #endif 96 97 SDT_PROVIDER_DECLARE(proc); 98 SDT_PROBE_DEFINE(proc, kernel, , exec, exec); 99 SDT_PROBE_ARGTYPE(proc, kernel, , exec, 0, "char *"); 100 SDT_PROBE_DEFINE(proc, kernel, , exec_failure, exec-failure); 101 SDT_PROBE_ARGTYPE(proc, kernel, , exec_failure, 0, "int"); 102 SDT_PROBE_DEFINE(proc, kernel, , exec_success, exec-success); 103 SDT_PROBE_ARGTYPE(proc, kernel, , exec_success, 0, "char *"); 104 105 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 106 107 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 108 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 109 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 110 static int do_execve(struct thread *td, struct image_args *args, 111 struct mac *mac_p); 112 113 /* XXX This should be vm_size_t. */ 114 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD, 115 NULL, 0, sysctl_kern_ps_strings, "LU", ""); 116 117 /* XXX This should be vm_size_t. */ 118 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 119 CTLFLAG_CAPRD, NULL, 0, sysctl_kern_usrstack, "LU", ""); 120 121 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 122 NULL, 0, sysctl_kern_stackprot, "I", ""); 123 124 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 125 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 126 &ps_arg_cache_limit, 0, ""); 127 128 static int map_at_zero = 0; 129 TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero); 130 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &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 int error; 284 285 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 286 args->begin_envv - args->begin_argv); 287 AUDIT_ARG_ENVV(args->begin_envv, args->envc, 288 args->endp - args->begin_envv); 289 if (p->p_flag & P_HADTHREADS) { 290 PROC_LOCK(p); 291 if (thread_single(SINGLE_BOUNDARY)) { 292 PROC_UNLOCK(p); 293 exec_free_args(args); 294 return (ERESTART); /* Try again later. */ 295 } 296 PROC_UNLOCK(p); 297 } 298 299 error = do_execve(td, args, mac_p); 300 301 if (p->p_flag & P_HADTHREADS) { 302 PROC_LOCK(p); 303 /* 304 * If success, we upgrade to SINGLE_EXIT state to 305 * force other threads to suicide. 306 */ 307 if (error == 0) 308 thread_single(SINGLE_EXIT); 309 else 310 thread_single_end(); 311 PROC_UNLOCK(p); 312 } 313 314 return (error); 315 } 316 317 /* 318 * In-kernel implementation of execve(). All arguments are assumed to be 319 * userspace pointers from the passed thread. 320 */ 321 static int 322 do_execve(td, args, mac_p) 323 struct thread *td; 324 struct image_args *args; 325 struct mac *mac_p; 326 { 327 struct proc *p = td->td_proc; 328 struct nameidata nd; 329 struct ucred *newcred = NULL, *oldcred; 330 struct uidinfo *euip; 331 register_t *stack_base; 332 int error, i; 333 struct image_params image_params, *imgp; 334 struct vattr attr; 335 int (*img_first)(struct image_params *); 336 struct pargs *oldargs = NULL, *newargs = NULL; 337 struct sigacts *oldsigacts, *newsigacts; 338 #ifdef KTRACE 339 struct vnode *tracevp = NULL; 340 struct ucred *tracecred = NULL; 341 #endif 342 struct vnode *textvp = NULL, *binvp = NULL; 343 int credential_changing; 344 int vfslocked; 345 int textset; 346 #ifdef MAC 347 struct label *interpvplabel = NULL; 348 int will_transition; 349 #endif 350 #ifdef HWPMC_HOOKS 351 struct pmckern_procexec pe; 352 #endif 353 static const char fexecv_proc_title[] = "(fexecv)"; 354 355 vfslocked = 0; 356 imgp = &image_params; 357 358 /* 359 * Lock the process and set the P_INEXEC flag to indicate that 360 * it should be left alone until we're done here. This is 361 * necessary to avoid race conditions - e.g. in ptrace() - 362 * that might allow a local user to illicitly obtain elevated 363 * privileges. 364 */ 365 PROC_LOCK(p); 366 KASSERT((p->p_flag & P_INEXEC) == 0, 367 ("%s(): process already has P_INEXEC flag", __func__)); 368 p->p_flag |= P_INEXEC; 369 PROC_UNLOCK(p); 370 371 /* 372 * Initialize part of the common data 373 */ 374 imgp->proc = p; 375 imgp->execlabel = NULL; 376 imgp->attr = &attr; 377 imgp->entry_addr = 0; 378 imgp->reloc_base = 0; 379 imgp->vmspace_destroyed = 0; 380 imgp->interpreted = 0; 381 imgp->opened = 0; 382 imgp->interpreter_name = NULL; 383 imgp->auxargs = NULL; 384 imgp->vp = NULL; 385 imgp->object = NULL; 386 imgp->firstpage = NULL; 387 imgp->ps_strings = 0; 388 imgp->auxarg_size = 0; 389 imgp->args = args; 390 imgp->execpath = imgp->freepath = NULL; 391 imgp->execpathp = 0; 392 imgp->canary = 0; 393 imgp->canarylen = 0; 394 imgp->pagesizes = 0; 395 imgp->pagesizeslen = 0; 396 imgp->stack_prot = 0; 397 398 #ifdef MAC 399 error = mac_execve_enter(imgp, mac_p); 400 if (error) 401 goto exec_fail; 402 #endif 403 404 imgp->image_header = NULL; 405 406 /* 407 * Translate the file name. namei() returns a vnode pointer 408 * in ni_vp amoung other things. 409 * 410 * XXXAUDIT: It would be desirable to also audit the name of the 411 * interpreter if this is an interpreted binary. 412 */ 413 if (args->fname != NULL) { 414 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 415 | MPSAFE | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 416 } 417 418 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 419 420 interpret: 421 if (args->fname != NULL) { 422 #ifdef CAPABILITY_MODE 423 /* 424 * While capability mode can't reach this point via direct 425 * path arguments to execve(), we also don't allow 426 * interpreters to be used in capability mode (for now). 427 * Catch indirect lookups and return a permissions error. 428 */ 429 if (IN_CAPABILITY_MODE(td)) { 430 error = ECAPMODE; 431 goto exec_fail; 432 } 433 #endif 434 error = namei(&nd); 435 if (error) 436 goto exec_fail; 437 438 vfslocked = NDHASGIANT(&nd); 439 binvp = nd.ni_vp; 440 imgp->vp = binvp; 441 } else { 442 AUDIT_ARG_FD(args->fd); 443 /* 444 * Some might argue that CAP_READ and/or CAP_MMAP should also 445 * be required here; such arguments will be entertained. 446 * 447 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 448 */ 449 error = fgetvp_exec(td, args->fd, CAP_FEXECVE, &binvp); 450 if (error) 451 goto exec_fail; 452 vfslocked = VFS_LOCK_GIANT(binvp->v_mount); 453 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY); 454 AUDIT_ARG_VNODE1(binvp); 455 imgp->vp = binvp; 456 } 457 458 /* 459 * Check file permissions (also 'opens' file) 460 */ 461 error = exec_check_permissions(imgp); 462 if (error) 463 goto exec_fail_dealloc; 464 465 imgp->object = imgp->vp->v_object; 466 if (imgp->object != NULL) 467 vm_object_reference(imgp->object); 468 469 /* 470 * Set VV_TEXT now so no one can write to the executable while we're 471 * activating it. 472 * 473 * Remember if this was set before and unset it in case this is not 474 * actually an executable image. 475 */ 476 textset = imgp->vp->v_vflag & VV_TEXT; 477 ASSERT_VOP_ELOCKED(imgp->vp, "vv_text"); 478 imgp->vp->v_vflag |= VV_TEXT; 479 480 error = exec_map_first_page(imgp); 481 if (error) 482 goto exec_fail_dealloc; 483 484 imgp->proc->p_osrel = 0; 485 /* 486 * If the current process has a special image activator it 487 * wants to try first, call it. For example, emulating shell 488 * scripts differently. 489 */ 490 error = -1; 491 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 492 error = img_first(imgp); 493 494 /* 495 * Loop through the list of image activators, calling each one. 496 * An activator returns -1 if there is no match, 0 on success, 497 * and an error otherwise. 498 */ 499 for (i = 0; error == -1 && execsw[i]; ++i) { 500 if (execsw[i]->ex_imgact == NULL || 501 execsw[i]->ex_imgact == img_first) { 502 continue; 503 } 504 error = (*execsw[i]->ex_imgact)(imgp); 505 } 506 507 if (error) { 508 if (error == -1) { 509 if (textset == 0) { 510 ASSERT_VOP_ELOCKED(imgp->vp, "vv_text"); 511 imgp->vp->v_vflag &= ~VV_TEXT; 512 } 513 error = ENOEXEC; 514 } 515 goto exec_fail_dealloc; 516 } 517 518 /* 519 * Special interpreter operation, cleanup and loop up to try to 520 * activate the interpreter. 521 */ 522 if (imgp->interpreted) { 523 exec_unmap_first_page(imgp); 524 /* 525 * VV_TEXT needs to be unset for scripts. There is a short 526 * period before we determine that something is a script where 527 * VV_TEXT will be set. The vnode lock is held over this 528 * entire period so nothing should illegitimately be blocked. 529 */ 530 imgp->vp->v_vflag &= ~VV_TEXT; 531 /* free name buffer and old vnode */ 532 if (args->fname != NULL) 533 NDFREE(&nd, NDF_ONLY_PNBUF); 534 #ifdef MAC 535 mac_execve_interpreter_enter(binvp, &interpvplabel); 536 #endif 537 if (imgp->opened) { 538 VOP_CLOSE(binvp, FREAD, td->td_ucred, td); 539 imgp->opened = 0; 540 } 541 vput(binvp); 542 vm_object_deallocate(imgp->object); 543 imgp->object = NULL; 544 VFS_UNLOCK_GIANT(vfslocked); 545 vfslocked = 0; 546 /* set new name to that of the interpreter */ 547 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME | MPSAFE, 548 UIO_SYSSPACE, imgp->interpreter_name, td); 549 args->fname = imgp->interpreter_name; 550 goto interpret; 551 } 552 553 /* 554 * NB: We unlock the vnode here because it is believed that none 555 * of the sv_copyout_strings/sv_fixup operations require the vnode. 556 */ 557 VOP_UNLOCK(imgp->vp, 0); 558 559 /* 560 * Do the best to calculate the full path to the image file. 561 */ 562 if (imgp->auxargs != NULL && 563 ((args->fname != NULL && args->fname[0] == '/') || 564 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0)) 565 imgp->execpath = args->fname; 566 567 /* 568 * Copy out strings (args and env) and initialize stack base 569 */ 570 if (p->p_sysent->sv_copyout_strings) 571 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 572 else 573 stack_base = exec_copyout_strings(imgp); 574 575 /* 576 * If custom stack fixup routine present for this process 577 * let it do the stack setup. 578 * Else stuff argument count as first item on stack 579 */ 580 if (p->p_sysent->sv_fixup != NULL) 581 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 582 else 583 suword(--stack_base, imgp->args->argc); 584 585 /* 586 * For security and other reasons, the file descriptor table cannot 587 * be shared after an exec. 588 */ 589 fdunshare(p, td); 590 591 /* 592 * Malloc things before we need locks. 593 */ 594 newcred = crget(); 595 euip = uifind(attr.va_uid); 596 i = imgp->args->begin_envv - imgp->args->begin_argv; 597 /* Cache arguments if they fit inside our allowance */ 598 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 599 newargs = pargs_alloc(i); 600 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 601 } 602 603 /* close files on exec */ 604 fdcloseexec(td); 605 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 606 607 /* Get a reference to the vnode prior to locking the proc */ 608 VREF(binvp); 609 610 /* 611 * For security and other reasons, signal handlers cannot 612 * be shared after an exec. The new process gets a copy of the old 613 * handlers. In execsigs(), the new process will have its signals 614 * reset. 615 */ 616 PROC_LOCK(p); 617 oldcred = crcopysafe(p, newcred); 618 if (sigacts_shared(p->p_sigacts)) { 619 oldsigacts = p->p_sigacts; 620 PROC_UNLOCK(p); 621 newsigacts = sigacts_alloc(); 622 sigacts_copy(newsigacts, oldsigacts); 623 PROC_LOCK(p); 624 p->p_sigacts = newsigacts; 625 } else 626 oldsigacts = NULL; 627 628 /* Stop profiling */ 629 stopprofclock(p); 630 631 /* reset caught signals */ 632 execsigs(p); 633 634 /* name this process - nameiexec(p, ndp) */ 635 bzero(p->p_comm, sizeof(p->p_comm)); 636 if (args->fname) 637 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 638 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 639 else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0) 640 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 641 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 642 #ifdef KTR 643 sched_clear_tdname(td); 644 #endif 645 646 /* 647 * mark as execed, wakeup the process that vforked (if any) and tell 648 * it that it now has its own resources back 649 */ 650 p->p_flag |= P_EXEC; 651 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 652 p->p_flag &= ~P_PPWAIT; 653 cv_broadcast(&p->p_pwait); 654 } 655 656 /* 657 * Implement image setuid/setgid. 658 * 659 * Don't honor setuid/setgid if the filesystem prohibits it or if 660 * the process is being traced. 661 * 662 * We disable setuid/setgid/etc in compatibility mode on the basis 663 * that most setugid applications are not written with that 664 * environment in mind, and will therefore almost certainly operate 665 * incorrectly. In principle there's no reason that setugid 666 * applications might not be useful in capability mode, so we may want 667 * to reconsider this conservative design choice in the future. 668 * 669 * XXXMAC: For the time being, use NOSUID to also prohibit 670 * transitions on the file system. 671 */ 672 credential_changing = 0; 673 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 674 attr.va_uid; 675 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 676 attr.va_gid; 677 #ifdef MAC 678 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 679 interpvplabel, imgp); 680 credential_changing |= will_transition; 681 #endif 682 683 if (credential_changing && 684 #ifdef CAPABILITY_MODE 685 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 686 #endif 687 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 688 (p->p_flag & P_TRACED) == 0) { 689 /* 690 * Turn off syscall tracing for set-id programs, except for 691 * root. Record any set-id flags first to make sure that 692 * we do not regain any tracing during a possible block. 693 */ 694 setsugid(p); 695 696 #ifdef KTRACE 697 if (priv_check_cred(oldcred, PRIV_DEBUG_DIFFCRED, 0)) 698 ktrprocexec(p, &tracecred, &tracevp); 699 #endif 700 /* 701 * Close any file descriptors 0..2 that reference procfs, 702 * then make sure file descriptors 0..2 are in use. 703 * 704 * setugidsafety() may call closef() and then pfind() 705 * which may grab the process lock. 706 * fdcheckstd() may call falloc() which may block to 707 * allocate memory, so temporarily drop the process lock. 708 */ 709 PROC_UNLOCK(p); 710 VOP_UNLOCK(imgp->vp, 0); 711 setugidsafety(td); 712 error = fdcheckstd(td); 713 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 714 if (error != 0) 715 goto done1; 716 PROC_LOCK(p); 717 /* 718 * Set the new credentials. 719 */ 720 if (attr.va_mode & S_ISUID) 721 change_euid(newcred, euip); 722 if (attr.va_mode & S_ISGID) 723 change_egid(newcred, attr.va_gid); 724 #ifdef MAC 725 if (will_transition) { 726 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 727 interpvplabel, imgp); 728 } 729 #endif 730 /* 731 * Implement correct POSIX saved-id behavior. 732 * 733 * XXXMAC: Note that the current logic will save the 734 * uid and gid if a MAC domain transition occurs, even 735 * though maybe it shouldn't. 736 */ 737 change_svuid(newcred, newcred->cr_uid); 738 change_svgid(newcred, newcred->cr_gid); 739 p->p_ucred = newcred; 740 newcred = NULL; 741 } else { 742 if (oldcred->cr_uid == oldcred->cr_ruid && 743 oldcred->cr_gid == oldcred->cr_rgid) 744 p->p_flag &= ~P_SUGID; 745 /* 746 * Implement correct POSIX saved-id behavior. 747 * 748 * XXX: It's not clear that the existing behavior is 749 * POSIX-compliant. A number of sources indicate that the 750 * saved uid/gid should only be updated if the new ruid is 751 * not equal to the old ruid, or the new euid is not equal 752 * to the old euid and the new euid is not equal to the old 753 * ruid. The FreeBSD code always updates the saved uid/gid. 754 * Also, this code uses the new (replaced) euid and egid as 755 * the source, which may or may not be the right ones to use. 756 */ 757 if (oldcred->cr_svuid != oldcred->cr_uid || 758 oldcred->cr_svgid != oldcred->cr_gid) { 759 change_svuid(newcred, newcred->cr_uid); 760 change_svgid(newcred, newcred->cr_gid); 761 p->p_ucred = newcred; 762 newcred = NULL; 763 } 764 } 765 766 /* 767 * Store the vp for use in procfs. This vnode was referenced prior 768 * to locking the proc lock. 769 */ 770 textvp = p->p_textvp; 771 p->p_textvp = binvp; 772 773 #ifdef KDTRACE_HOOKS 774 /* 775 * Tell the DTrace fasttrap provider about the exec if it 776 * has declared an interest. 777 */ 778 if (dtrace_fasttrap_exec) 779 dtrace_fasttrap_exec(p); 780 #endif 781 782 /* 783 * Notify others that we exec'd, and clear the P_INEXEC flag 784 * as we're now a bona fide freshly-execed process. 785 */ 786 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 787 p->p_flag &= ~P_INEXEC; 788 789 /* clear "fork but no exec" flag, as we _are_ execing */ 790 p->p_acflag &= ~AFORK; 791 792 /* 793 * Free any previous argument cache and replace it with 794 * the new argument cache, if any. 795 */ 796 oldargs = p->p_args; 797 p->p_args = newargs; 798 newargs = NULL; 799 800 #ifdef HWPMC_HOOKS 801 /* 802 * Check if system-wide sampling is in effect or if the 803 * current process is using PMCs. If so, do exec() time 804 * processing. This processing needs to happen AFTER the 805 * P_INEXEC flag is cleared. 806 * 807 * The proc lock needs to be released before taking the PMC 808 * SX. 809 */ 810 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 811 PROC_UNLOCK(p); 812 VOP_UNLOCK(imgp->vp, 0); 813 pe.pm_credentialschanged = credential_changing; 814 pe.pm_entryaddr = imgp->entry_addr; 815 816 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 817 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 818 } else 819 PROC_UNLOCK(p); 820 #else /* !HWPMC_HOOKS */ 821 PROC_UNLOCK(p); 822 #endif 823 824 /* Set values passed into the program in registers. */ 825 if (p->p_sysent->sv_setregs) 826 (*p->p_sysent->sv_setregs)(td, imgp, 827 (u_long)(uintptr_t)stack_base); 828 else 829 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 830 831 vfs_mark_atime(imgp->vp, td->td_ucred); 832 833 SDT_PROBE(proc, kernel, , exec_success, args->fname, 0, 0, 0, 0); 834 835 done1: 836 /* 837 * Free any resources malloc'd earlier that we didn't use. 838 */ 839 uifree(euip); 840 if (newcred == NULL) 841 crfree(oldcred); 842 else 843 crfree(newcred); 844 VOP_UNLOCK(imgp->vp, 0); 845 846 /* 847 * Handle deferred decrement of ref counts. 848 */ 849 if (textvp != NULL) { 850 int tvfslocked; 851 852 tvfslocked = VFS_LOCK_GIANT(textvp->v_mount); 853 vrele(textvp); 854 VFS_UNLOCK_GIANT(tvfslocked); 855 } 856 if (binvp && error != 0) 857 vrele(binvp); 858 #ifdef KTRACE 859 if (tracevp != NULL) { 860 int tvfslocked; 861 862 tvfslocked = VFS_LOCK_GIANT(tracevp->v_mount); 863 vrele(tracevp); 864 VFS_UNLOCK_GIANT(tvfslocked); 865 } 866 if (tracecred != NULL) 867 crfree(tracecred); 868 #endif 869 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 870 pargs_drop(oldargs); 871 pargs_drop(newargs); 872 if (oldsigacts != NULL) 873 sigacts_free(oldsigacts); 874 875 exec_fail_dealloc: 876 877 /* 878 * free various allocated resources 879 */ 880 if (imgp->firstpage != NULL) 881 exec_unmap_first_page(imgp); 882 883 if (imgp->vp != NULL) { 884 if (args->fname) 885 NDFREE(&nd, NDF_ONLY_PNBUF); 886 if (imgp->opened) 887 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 888 vput(imgp->vp); 889 } 890 891 if (imgp->object != NULL) 892 vm_object_deallocate(imgp->object); 893 894 free(imgp->freepath, M_TEMP); 895 896 if (error == 0) { 897 PROC_LOCK(p); 898 td->td_dbgflags |= TDB_EXEC; 899 PROC_UNLOCK(p); 900 901 /* 902 * Stop the process here if its stop event mask has 903 * the S_EXEC bit set. 904 */ 905 STOPEVENT(p, S_EXEC, 0); 906 goto done2; 907 } 908 909 exec_fail: 910 /* we're done here, clear P_INEXEC */ 911 PROC_LOCK(p); 912 p->p_flag &= ~P_INEXEC; 913 PROC_UNLOCK(p); 914 915 SDT_PROBE(proc, kernel, , exec_failure, error, 0, 0, 0, 0); 916 917 done2: 918 #ifdef MAC 919 mac_execve_exit(imgp); 920 mac_execve_interpreter_exit(interpvplabel); 921 #endif 922 VFS_UNLOCK_GIANT(vfslocked); 923 exec_free_args(args); 924 925 if (error && imgp->vmspace_destroyed) { 926 /* sorry, no more process anymore. exit gracefully */ 927 exit1(td, W_EXITCODE(0, SIGABRT)); 928 /* NOT REACHED */ 929 } 930 931 #ifdef KTRACE 932 if (error == 0) 933 ktrprocctor(p); 934 #endif 935 936 return (error); 937 } 938 939 int 940 exec_map_first_page(imgp) 941 struct image_params *imgp; 942 { 943 int rv, i; 944 int initial_pagein; 945 vm_page_t ma[VM_INITIAL_PAGEIN]; 946 vm_object_t object; 947 948 if (imgp->firstpage != NULL) 949 exec_unmap_first_page(imgp); 950 951 object = imgp->vp->v_object; 952 if (object == NULL) 953 return (EACCES); 954 VM_OBJECT_LOCK(object); 955 #if VM_NRESERVLEVEL > 0 956 if ((object->flags & OBJ_COLORED) == 0) { 957 object->flags |= OBJ_COLORED; 958 object->pg_color = 0; 959 } 960 #endif 961 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 962 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 963 initial_pagein = VM_INITIAL_PAGEIN; 964 if (initial_pagein > object->size) 965 initial_pagein = object->size; 966 for (i = 1; i < initial_pagein; i++) { 967 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 968 if (ma[i]->valid) 969 break; 970 if ((ma[i]->oflags & VPO_BUSY) || ma[i]->busy) 971 break; 972 vm_page_busy(ma[i]); 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_UNLOCK(object); 990 return (EIO); 991 } 992 } 993 vm_page_lock(ma[0]); 994 vm_page_hold(ma[0]); 995 vm_page_unlock(ma[0]); 996 vm_page_wakeup(ma[0]); 997 VM_OBJECT_UNLOCK(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, VM_PROT_ALL, 1075 MAP_COPY_ON_WRITE | MAP_ACC_NO_CHARGE); 1076 if (error) { 1077 vm_object_deallocate(obj); 1078 return (error); 1079 } 1080 } 1081 1082 /* Allocate a new stack */ 1083 if (sv->sv_maxssiz != NULL) 1084 ssiz = *sv->sv_maxssiz; 1085 else 1086 ssiz = maxssiz; 1087 stack_addr = sv->sv_usrstack - ssiz; 1088 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1089 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1090 sv->sv_stackprot, 1091 VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1092 if (error) 1093 return (error); 1094 1095 #ifdef __ia64__ 1096 /* Allocate a new register stack */ 1097 stack_addr = IA64_BACKINGSTORE; 1098 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1099 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP); 1100 if (error) 1101 return (error); 1102 #endif 1103 1104 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 1105 * VM_STACK case, but they are still used to monitor the size of the 1106 * process stack so we can check the stack rlimit. 1107 */ 1108 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1109 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1110 1111 return (0); 1112 } 1113 1114 /* 1115 * Copy out argument and environment strings from the old process address 1116 * space into the temporary string buffer. 1117 */ 1118 int 1119 exec_copyin_args(struct image_args *args, char *fname, 1120 enum uio_seg segflg, char **argv, char **envv) 1121 { 1122 char *argp, *envp; 1123 int error; 1124 size_t length; 1125 1126 bzero(args, sizeof(*args)); 1127 if (argv == NULL) 1128 return (EFAULT); 1129 1130 /* 1131 * Allocate demand-paged memory for the file name, argument, and 1132 * environment strings. 1133 */ 1134 error = exec_alloc_args(args); 1135 if (error != 0) 1136 return (error); 1137 1138 /* 1139 * Copy the file name. 1140 */ 1141 if (fname != NULL) { 1142 args->fname = args->buf; 1143 error = (segflg == UIO_SYSSPACE) ? 1144 copystr(fname, args->fname, PATH_MAX, &length) : 1145 copyinstr(fname, args->fname, PATH_MAX, &length); 1146 if (error != 0) 1147 goto err_exit; 1148 } else 1149 length = 0; 1150 1151 args->begin_argv = args->buf + length; 1152 args->endp = args->begin_argv; 1153 args->stringspace = ARG_MAX; 1154 1155 /* 1156 * extract arguments first 1157 */ 1158 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 1159 if (argp == (caddr_t) -1) { 1160 error = EFAULT; 1161 goto err_exit; 1162 } 1163 if ((error = copyinstr(argp, args->endp, 1164 args->stringspace, &length))) { 1165 if (error == ENAMETOOLONG) 1166 error = E2BIG; 1167 goto err_exit; 1168 } 1169 args->stringspace -= length; 1170 args->endp += length; 1171 args->argc++; 1172 } 1173 1174 args->begin_envv = args->endp; 1175 1176 /* 1177 * extract environment strings 1178 */ 1179 if (envv) { 1180 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) { 1181 if (envp == (caddr_t)-1) { 1182 error = EFAULT; 1183 goto err_exit; 1184 } 1185 if ((error = copyinstr(envp, args->endp, 1186 args->stringspace, &length))) { 1187 if (error == ENAMETOOLONG) 1188 error = E2BIG; 1189 goto err_exit; 1190 } 1191 args->stringspace -= length; 1192 args->endp += length; 1193 args->envc++; 1194 } 1195 } 1196 1197 return (0); 1198 1199 err_exit: 1200 exec_free_args(args); 1201 return (error); 1202 } 1203 1204 /* 1205 * Allocate temporary demand-paged, zero-filled memory for the file name, 1206 * argument, and environment strings. Returns zero if the allocation succeeds 1207 * and ENOMEM otherwise. 1208 */ 1209 int 1210 exec_alloc_args(struct image_args *args) 1211 { 1212 1213 args->buf = (char *)kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 1214 return (args->buf != NULL ? 0 : ENOMEM); 1215 } 1216 1217 void 1218 exec_free_args(struct image_args *args) 1219 { 1220 1221 if (args->buf != NULL) { 1222 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf, 1223 PATH_MAX + ARG_MAX); 1224 args->buf = NULL; 1225 } 1226 if (args->fname_buf != NULL) { 1227 free(args->fname_buf, M_TEMP); 1228 args->fname_buf = NULL; 1229 } 1230 } 1231 1232 /* 1233 * Copy strings out to the new process address space, constructing new arg 1234 * and env vector tables. Return a pointer to the base so that it can be used 1235 * as the initial stack pointer. 1236 */ 1237 register_t * 1238 exec_copyout_strings(imgp) 1239 struct image_params *imgp; 1240 { 1241 int argc, envc; 1242 char **vectp; 1243 char *stringp, *destp; 1244 register_t *stack_base; 1245 struct ps_strings *arginfo; 1246 struct proc *p; 1247 size_t execpath_len; 1248 int szsigcode, szps; 1249 char canary[sizeof(long) * 8]; 1250 1251 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1252 /* 1253 * Calculate string base and vector table pointers. 1254 * Also deal with signal trampoline code for this exec type. 1255 */ 1256 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1257 execpath_len = strlen(imgp->execpath) + 1; 1258 else 1259 execpath_len = 0; 1260 p = imgp->proc; 1261 szsigcode = 0; 1262 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1263 if (p->p_sysent->sv_sigcode_base == 0) { 1264 if (p->p_sysent->sv_szsigcode != NULL) 1265 szsigcode = *(p->p_sysent->sv_szsigcode); 1266 } 1267 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 1268 roundup(execpath_len, sizeof(char *)) - 1269 roundup(sizeof(canary), sizeof(char *)) - 1270 roundup(szps, sizeof(char *)) - 1271 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *)); 1272 1273 /* 1274 * install sigcode 1275 */ 1276 if (szsigcode != 0) 1277 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo - 1278 szsigcode), szsigcode); 1279 1280 /* 1281 * Copy the image path for the rtld. 1282 */ 1283 if (execpath_len != 0) { 1284 imgp->execpathp = (uintptr_t)arginfo - szsigcode - execpath_len; 1285 copyout(imgp->execpath, (void *)imgp->execpathp, 1286 execpath_len); 1287 } 1288 1289 /* 1290 * Prepare the canary for SSP. 1291 */ 1292 arc4rand(canary, sizeof(canary), 0); 1293 imgp->canary = (uintptr_t)arginfo - szsigcode - execpath_len - 1294 sizeof(canary); 1295 copyout(canary, (void *)imgp->canary, sizeof(canary)); 1296 imgp->canarylen = sizeof(canary); 1297 1298 /* 1299 * Prepare the pagesizes array. 1300 */ 1301 imgp->pagesizes = (uintptr_t)arginfo - szsigcode - execpath_len - 1302 roundup(sizeof(canary), sizeof(char *)) - szps; 1303 copyout(pagesizes, (void *)imgp->pagesizes, szps); 1304 imgp->pagesizeslen = szps; 1305 1306 /* 1307 * If we have a valid auxargs ptr, prepare some room 1308 * on the stack. 1309 */ 1310 if (imgp->auxargs) { 1311 /* 1312 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1313 * lower compatibility. 1314 */ 1315 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1316 (AT_COUNT * 2); 1317 /* 1318 * The '+ 2' is for the null pointers at the end of each of 1319 * the arg and env vector sets,and imgp->auxarg_size is room 1320 * for argument of Runtime loader. 1321 */ 1322 vectp = (char **)(destp - (imgp->args->argc + 1323 imgp->args->envc + 2 + imgp->auxarg_size) 1324 * sizeof(char *)); 1325 } else { 1326 /* 1327 * The '+ 2' is for the null pointers at the end of each of 1328 * the arg and env vector sets 1329 */ 1330 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) * 1331 sizeof(char *)); 1332 } 1333 1334 /* 1335 * vectp also becomes our initial stack base 1336 */ 1337 stack_base = (register_t *)vectp; 1338 1339 stringp = imgp->args->begin_argv; 1340 argc = imgp->args->argc; 1341 envc = imgp->args->envc; 1342 1343 /* 1344 * Copy out strings - arguments and environment. 1345 */ 1346 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace); 1347 1348 /* 1349 * Fill in "ps_strings" struct for ps, w, etc. 1350 */ 1351 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1352 suword32(&arginfo->ps_nargvstr, argc); 1353 1354 /* 1355 * Fill in argument portion of vector table. 1356 */ 1357 for (; argc > 0; --argc) { 1358 suword(vectp++, (long)(intptr_t)destp); 1359 while (*stringp++ != 0) 1360 destp++; 1361 destp++; 1362 } 1363 1364 /* a null vector table pointer separates the argp's from the envp's */ 1365 suword(vectp++, 0); 1366 1367 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1368 suword32(&arginfo->ps_nenvstr, envc); 1369 1370 /* 1371 * Fill in environment portion of vector table. 1372 */ 1373 for (; envc > 0; --envc) { 1374 suword(vectp++, (long)(intptr_t)destp); 1375 while (*stringp++ != 0) 1376 destp++; 1377 destp++; 1378 } 1379 1380 /* end of vector table is a null pointer */ 1381 suword(vectp, 0); 1382 1383 return (stack_base); 1384 } 1385 1386 /* 1387 * Check permissions of file to execute. 1388 * Called with imgp->vp locked. 1389 * Return 0 for success or error code on failure. 1390 */ 1391 int 1392 exec_check_permissions(imgp) 1393 struct image_params *imgp; 1394 { 1395 struct vnode *vp = imgp->vp; 1396 struct vattr *attr = imgp->attr; 1397 struct thread *td; 1398 int error; 1399 1400 td = curthread; 1401 1402 /* Get file attributes */ 1403 error = VOP_GETATTR(vp, attr, td->td_ucred); 1404 if (error) 1405 return (error); 1406 1407 #ifdef MAC 1408 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1409 if (error) 1410 return (error); 1411 #endif 1412 1413 /* 1414 * 1) Check if file execution is disabled for the filesystem that 1415 * this file resides on. 1416 * 2) Ensure that at least one execute bit is on. Otherwise, a 1417 * privileged user will always succeed, and we don't want this 1418 * to happen unless the file really is executable. 1419 * 3) Ensure that the file is a regular file. 1420 */ 1421 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1422 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1423 (attr->va_type != VREG)) 1424 return (EACCES); 1425 1426 /* 1427 * Zero length files can't be exec'd 1428 */ 1429 if (attr->va_size == 0) 1430 return (ENOEXEC); 1431 1432 /* 1433 * Check for execute permission to file based on current credentials. 1434 */ 1435 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1436 if (error) 1437 return (error); 1438 1439 /* 1440 * Check number of open-for-writes on the file and deny execution 1441 * if there are any. 1442 */ 1443 if (vp->v_writecount) 1444 return (ETXTBSY); 1445 1446 /* 1447 * Call filesystem specific open routine (which does nothing in the 1448 * general case). 1449 */ 1450 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1451 if (error == 0) 1452 imgp->opened = 1; 1453 return (error); 1454 } 1455 1456 /* 1457 * Exec handler registration 1458 */ 1459 int 1460 exec_register(execsw_arg) 1461 const struct execsw *execsw_arg; 1462 { 1463 const struct execsw **es, **xs, **newexecsw; 1464 int count = 2; /* New slot and trailing NULL */ 1465 1466 if (execsw) 1467 for (es = execsw; *es; es++) 1468 count++; 1469 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1470 if (newexecsw == NULL) 1471 return (ENOMEM); 1472 xs = newexecsw; 1473 if (execsw) 1474 for (es = execsw; *es; es++) 1475 *xs++ = *es; 1476 *xs++ = execsw_arg; 1477 *xs = NULL; 1478 if (execsw) 1479 free(execsw, M_TEMP); 1480 execsw = newexecsw; 1481 return (0); 1482 } 1483 1484 int 1485 exec_unregister(execsw_arg) 1486 const struct execsw *execsw_arg; 1487 { 1488 const struct execsw **es, **xs, **newexecsw; 1489 int count = 1; 1490 1491 if (execsw == NULL) 1492 panic("unregister with no handlers left?\n"); 1493 1494 for (es = execsw; *es; es++) { 1495 if (*es == execsw_arg) 1496 break; 1497 } 1498 if (*es == NULL) 1499 return (ENOENT); 1500 for (es = execsw; *es; es++) 1501 if (*es != execsw_arg) 1502 count++; 1503 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1504 if (newexecsw == NULL) 1505 return (ENOMEM); 1506 xs = newexecsw; 1507 for (es = execsw; *es; es++) 1508 if (*es != execsw_arg) 1509 *xs++ = *es; 1510 *xs = NULL; 1511 if (execsw) 1512 free(execsw, M_TEMP); 1513 execsw = newexecsw; 1514 return (0); 1515 } 1516