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_hwpmc_hooks.h" 31 #include "opt_kdtrace.h" 32 #include "opt_ktrace.h" 33 #include "opt_vm.h" 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/eventhandler.h> 38 #include <sys/lock.h> 39 #include <sys/mutex.h> 40 #include <sys/sysproto.h> 41 #include <sys/signalvar.h> 42 #include <sys/kernel.h> 43 #include <sys/mount.h> 44 #include <sys/filedesc.h> 45 #include <sys/fcntl.h> 46 #include <sys/acct.h> 47 #include <sys/exec.h> 48 #include <sys/imgact.h> 49 #include <sys/imgact_elf.h> 50 #include <sys/wait.h> 51 #include <sys/malloc.h> 52 #include <sys/priv.h> 53 #include <sys/proc.h> 54 #include <sys/pioctl.h> 55 #include <sys/namei.h> 56 #include <sys/resourcevar.h> 57 #include <sys/sdt.h> 58 #include <sys/sf_buf.h> 59 #include <sys/syscallsubr.h> 60 #include <sys/sysent.h> 61 #include <sys/shm.h> 62 #include <sys/sysctl.h> 63 #include <sys/vnode.h> 64 #include <sys/stat.h> 65 #ifdef KTRACE 66 #include <sys/ktrace.h> 67 #endif 68 69 #include <vm/vm.h> 70 #include <vm/vm_param.h> 71 #include <vm/pmap.h> 72 #include <vm/vm_page.h> 73 #include <vm/vm_map.h> 74 #include <vm/vm_kern.h> 75 #include <vm/vm_extern.h> 76 #include <vm/vm_object.h> 77 #include <vm/vm_pager.h> 78 79 #ifdef HWPMC_HOOKS 80 #include <sys/pmckern.h> 81 #endif 82 83 #include <machine/reg.h> 84 85 #include <security/audit/audit.h> 86 #include <security/mac/mac_framework.h> 87 88 #ifdef KDTRACE_HOOKS 89 #include <sys/dtrace_bsd.h> 90 dtrace_execexit_func_t dtrace_fasttrap_exec; 91 #endif 92 93 SDT_PROVIDER_DECLARE(proc); 94 SDT_PROBE_DEFINE(proc, kernel, , exec, exec); 95 SDT_PROBE_ARGTYPE(proc, kernel, , exec, 0, "char *"); 96 SDT_PROBE_DEFINE(proc, kernel, , exec_failure, exec-failure); 97 SDT_PROBE_ARGTYPE(proc, kernel, , exec_failure, 0, "int"); 98 SDT_PROBE_DEFINE(proc, kernel, , exec_success, exec-success); 99 SDT_PROBE_ARGTYPE(proc, kernel, , exec_success, 0, "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 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 map_at_zero = 0; 125 TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero); 126 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &map_at_zero, 0, 127 "Permit processes to map an object at virtual address 0."); 128 129 static int 130 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 131 { 132 struct proc *p; 133 int error; 134 135 p = curproc; 136 #ifdef SCTL_MASK32 137 if (req->flags & SCTL_MASK32) { 138 unsigned int val; 139 val = (unsigned int)p->p_sysent->sv_psstrings; 140 error = SYSCTL_OUT(req, &val, sizeof(val)); 141 } else 142 #endif 143 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 144 sizeof(p->p_sysent->sv_psstrings)); 145 return error; 146 } 147 148 static int 149 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 150 { 151 struct proc *p; 152 int error; 153 154 p = curproc; 155 #ifdef SCTL_MASK32 156 if (req->flags & SCTL_MASK32) { 157 unsigned int val; 158 val = (unsigned int)p->p_sysent->sv_usrstack; 159 error = SYSCTL_OUT(req, &val, sizeof(val)); 160 } else 161 #endif 162 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 163 sizeof(p->p_sysent->sv_usrstack)); 164 return error; 165 } 166 167 static int 168 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 169 { 170 struct proc *p; 171 172 p = curproc; 173 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 174 sizeof(p->p_sysent->sv_stackprot))); 175 } 176 177 /* 178 * Each of the items is a pointer to a `const struct execsw', hence the 179 * double pointer here. 180 */ 181 static const struct execsw **execsw; 182 183 #ifndef _SYS_SYSPROTO_H_ 184 struct execve_args { 185 char *fname; 186 char **argv; 187 char **envv; 188 }; 189 #endif 190 191 int 192 execve(td, uap) 193 struct thread *td; 194 struct execve_args /* { 195 char *fname; 196 char **argv; 197 char **envv; 198 } */ *uap; 199 { 200 int error; 201 struct image_args args; 202 203 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 204 uap->argv, uap->envv); 205 if (error == 0) 206 error = kern_execve(td, &args, NULL); 207 return (error); 208 } 209 210 #ifndef _SYS_SYSPROTO_H_ 211 struct fexecve_args { 212 int fd; 213 char **argv; 214 char **envv; 215 } 216 #endif 217 int 218 fexecve(struct thread *td, struct fexecve_args *uap) 219 { 220 int error; 221 struct image_args args; 222 223 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 224 uap->argv, uap->envv); 225 if (error == 0) { 226 args.fd = uap->fd; 227 error = kern_execve(td, &args, NULL); 228 } 229 return (error); 230 } 231 232 #ifndef _SYS_SYSPROTO_H_ 233 struct __mac_execve_args { 234 char *fname; 235 char **argv; 236 char **envv; 237 struct mac *mac_p; 238 }; 239 #endif 240 241 int 242 __mac_execve(td, uap) 243 struct thread *td; 244 struct __mac_execve_args /* { 245 char *fname; 246 char **argv; 247 char **envv; 248 struct mac *mac_p; 249 } */ *uap; 250 { 251 #ifdef MAC 252 int error; 253 struct image_args args; 254 255 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 256 uap->argv, uap->envv); 257 if (error == 0) 258 error = kern_execve(td, &args, uap->mac_p); 259 return (error); 260 #else 261 return (ENOSYS); 262 #endif 263 } 264 265 /* 266 * XXX: kern_execve has the astonishing property of not always returning to 267 * the caller. If sufficiently bad things happen during the call to 268 * do_execve(), it can end up calling exit1(); as a result, callers must 269 * avoid doing anything which they might need to undo (e.g., allocating 270 * memory). 271 */ 272 int 273 kern_execve(td, args, mac_p) 274 struct thread *td; 275 struct image_args *args; 276 struct mac *mac_p; 277 { 278 struct proc *p = td->td_proc; 279 int error; 280 281 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 282 args->begin_envv - args->begin_argv); 283 AUDIT_ARG_ENVV(args->begin_envv, args->envc, 284 args->endp - args->begin_envv); 285 if (p->p_flag & P_HADTHREADS) { 286 PROC_LOCK(p); 287 if (thread_single(SINGLE_BOUNDARY)) { 288 PROC_UNLOCK(p); 289 exec_free_args(args); 290 return (ERESTART); /* Try again later. */ 291 } 292 PROC_UNLOCK(p); 293 } 294 295 error = do_execve(td, args, mac_p); 296 297 if (p->p_flag & P_HADTHREADS) { 298 PROC_LOCK(p); 299 /* 300 * If success, we upgrade to SINGLE_EXIT state to 301 * force other threads to suicide. 302 */ 303 if (error == 0) 304 thread_single(SINGLE_EXIT); 305 else 306 thread_single_end(); 307 PROC_UNLOCK(p); 308 } 309 310 return (error); 311 } 312 313 /* 314 * In-kernel implementation of execve(). All arguments are assumed to be 315 * userspace pointers from the passed thread. 316 */ 317 static int 318 do_execve(td, args, mac_p) 319 struct thread *td; 320 struct image_args *args; 321 struct mac *mac_p; 322 { 323 struct proc *p = td->td_proc; 324 struct nameidata nd; 325 struct ucred *newcred = NULL, *oldcred; 326 struct uidinfo *euip; 327 register_t *stack_base; 328 int error, i; 329 struct image_params image_params, *imgp; 330 struct vattr attr; 331 int (*img_first)(struct image_params *); 332 struct pargs *oldargs = NULL, *newargs = NULL; 333 struct sigacts *oldsigacts, *newsigacts; 334 #ifdef KTRACE 335 struct vnode *tracevp = NULL; 336 struct ucred *tracecred = NULL; 337 #endif 338 struct vnode *textvp = NULL, *binvp = NULL; 339 int credential_changing; 340 int vfslocked; 341 int textset; 342 #ifdef MAC 343 struct label *interpvplabel = NULL; 344 int will_transition; 345 #endif 346 #ifdef HWPMC_HOOKS 347 struct pmckern_procexec pe; 348 #endif 349 static const char fexecv_proc_title[] = "(fexecv)"; 350 351 vfslocked = 0; 352 imgp = &image_params; 353 354 /* 355 * Lock the process and set the P_INEXEC flag to indicate that 356 * it should be left alone until we're done here. This is 357 * necessary to avoid race conditions - e.g. in ptrace() - 358 * that might allow a local user to illicitly obtain elevated 359 * privileges. 360 */ 361 PROC_LOCK(p); 362 KASSERT((p->p_flag & P_INEXEC) == 0, 363 ("%s(): process already has P_INEXEC flag", __func__)); 364 p->p_flag |= P_INEXEC; 365 PROC_UNLOCK(p); 366 367 /* 368 * Initialize part of the common data 369 */ 370 imgp->proc = p; 371 imgp->execlabel = NULL; 372 imgp->attr = &attr; 373 imgp->entry_addr = 0; 374 imgp->reloc_base = 0; 375 imgp->vmspace_destroyed = 0; 376 imgp->interpreted = 0; 377 imgp->opened = 0; 378 imgp->interpreter_name = NULL; 379 imgp->auxargs = NULL; 380 imgp->vp = NULL; 381 imgp->object = NULL; 382 imgp->firstpage = NULL; 383 imgp->ps_strings = 0; 384 imgp->auxarg_size = 0; 385 imgp->args = args; 386 imgp->execpath = imgp->freepath = NULL; 387 imgp->execpathp = 0; 388 imgp->canary = 0; 389 imgp->canarylen = 0; 390 imgp->pagesizes = 0; 391 imgp->pagesizeslen = 0; 392 imgp->stack_prot = 0; 393 394 #ifdef MAC 395 error = mac_execve_enter(imgp, mac_p); 396 if (error) 397 goto exec_fail; 398 #endif 399 400 imgp->image_header = NULL; 401 402 /* 403 * Translate the file name. namei() returns a vnode pointer 404 * in ni_vp amoung other things. 405 * 406 * XXXAUDIT: It would be desirable to also audit the name of the 407 * interpreter if this is an interpreted binary. 408 */ 409 if (args->fname != NULL) { 410 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 411 | MPSAFE | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 412 } 413 414 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 415 416 interpret: 417 if (args->fname != NULL) { 418 error = namei(&nd); 419 if (error) 420 goto exec_fail; 421 422 vfslocked = NDHASGIANT(&nd); 423 binvp = nd.ni_vp; 424 imgp->vp = binvp; 425 } else { 426 AUDIT_ARG_FD(args->fd); 427 error = fgetvp(td, args->fd, &binvp); 428 if (error) 429 goto exec_fail; 430 vfslocked = VFS_LOCK_GIANT(binvp->v_mount); 431 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY); 432 AUDIT_ARG_VNODE1(binvp); 433 imgp->vp = binvp; 434 } 435 436 /* 437 * Check file permissions (also 'opens' file) 438 */ 439 error = exec_check_permissions(imgp); 440 if (error) 441 goto exec_fail_dealloc; 442 443 imgp->object = imgp->vp->v_object; 444 if (imgp->object != NULL) 445 vm_object_reference(imgp->object); 446 447 /* 448 * Set VV_TEXT now so no one can write to the executable while we're 449 * activating it. 450 * 451 * Remember if this was set before and unset it in case this is not 452 * actually an executable image. 453 */ 454 textset = imgp->vp->v_vflag & VV_TEXT; 455 imgp->vp->v_vflag |= VV_TEXT; 456 457 error = exec_map_first_page(imgp); 458 if (error) 459 goto exec_fail_dealloc; 460 461 imgp->proc->p_osrel = 0; 462 /* 463 * If the current process has a special image activator it 464 * wants to try first, call it. For example, emulating shell 465 * scripts differently. 466 */ 467 error = -1; 468 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 469 error = img_first(imgp); 470 471 /* 472 * Loop through the list of image activators, calling each one. 473 * An activator returns -1 if there is no match, 0 on success, 474 * and an error otherwise. 475 */ 476 for (i = 0; error == -1 && execsw[i]; ++i) { 477 if (execsw[i]->ex_imgact == NULL || 478 execsw[i]->ex_imgact == img_first) { 479 continue; 480 } 481 error = (*execsw[i]->ex_imgact)(imgp); 482 } 483 484 if (error) { 485 if (error == -1) { 486 if (textset == 0) 487 imgp->vp->v_vflag &= ~VV_TEXT; 488 error = ENOEXEC; 489 } 490 goto exec_fail_dealloc; 491 } 492 493 /* 494 * Special interpreter operation, cleanup and loop up to try to 495 * activate the interpreter. 496 */ 497 if (imgp->interpreted) { 498 exec_unmap_first_page(imgp); 499 /* 500 * VV_TEXT needs to be unset for scripts. There is a short 501 * period before we determine that something is a script where 502 * VV_TEXT will be set. The vnode lock is held over this 503 * entire period so nothing should illegitimately be blocked. 504 */ 505 imgp->vp->v_vflag &= ~VV_TEXT; 506 /* free name buffer and old vnode */ 507 if (args->fname != NULL) 508 NDFREE(&nd, NDF_ONLY_PNBUF); 509 #ifdef MAC 510 mac_execve_interpreter_enter(binvp, &interpvplabel); 511 #endif 512 if (imgp->opened) { 513 VOP_CLOSE(binvp, FREAD, td->td_ucred, td); 514 imgp->opened = 0; 515 } 516 vput(binvp); 517 vm_object_deallocate(imgp->object); 518 imgp->object = NULL; 519 VFS_UNLOCK_GIANT(vfslocked); 520 vfslocked = 0; 521 /* set new name to that of the interpreter */ 522 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME | MPSAFE, 523 UIO_SYSSPACE, imgp->interpreter_name, td); 524 args->fname = imgp->interpreter_name; 525 goto interpret; 526 } 527 528 /* 529 * NB: We unlock the vnode here because it is believed that none 530 * of the sv_copyout_strings/sv_fixup operations require the vnode. 531 */ 532 VOP_UNLOCK(imgp->vp, 0); 533 534 /* 535 * Do the best to calculate the full path to the image file. 536 */ 537 if (imgp->auxargs != NULL && 538 ((args->fname != NULL && args->fname[0] == '/') || 539 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0)) 540 imgp->execpath = args->fname; 541 542 /* 543 * Copy out strings (args and env) and initialize stack base 544 */ 545 if (p->p_sysent->sv_copyout_strings) 546 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 547 else 548 stack_base = exec_copyout_strings(imgp); 549 550 /* 551 * If custom stack fixup routine present for this process 552 * let it do the stack setup. 553 * Else stuff argument count as first item on stack 554 */ 555 if (p->p_sysent->sv_fixup != NULL) 556 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 557 else 558 suword(--stack_base, imgp->args->argc); 559 560 /* 561 * For security and other reasons, the file descriptor table cannot 562 * be shared after an exec. 563 */ 564 fdunshare(p, td); 565 566 /* 567 * Malloc things before we need locks. 568 */ 569 newcred = crget(); 570 euip = uifind(attr.va_uid); 571 i = imgp->args->begin_envv - imgp->args->begin_argv; 572 /* Cache arguments if they fit inside our allowance */ 573 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 574 newargs = pargs_alloc(i); 575 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 576 } 577 578 /* close files on exec */ 579 fdcloseexec(td); 580 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 581 582 /* Get a reference to the vnode prior to locking the proc */ 583 VREF(binvp); 584 585 /* 586 * For security and other reasons, signal handlers cannot 587 * be shared after an exec. The new process gets a copy of the old 588 * handlers. In execsigs(), the new process will have its signals 589 * reset. 590 */ 591 PROC_LOCK(p); 592 oldcred = crcopysafe(p, newcred); 593 if (sigacts_shared(p->p_sigacts)) { 594 oldsigacts = p->p_sigacts; 595 PROC_UNLOCK(p); 596 newsigacts = sigacts_alloc(); 597 sigacts_copy(newsigacts, oldsigacts); 598 PROC_LOCK(p); 599 p->p_sigacts = newsigacts; 600 } else 601 oldsigacts = NULL; 602 603 /* Stop profiling */ 604 stopprofclock(p); 605 606 /* reset caught signals */ 607 execsigs(p); 608 609 /* name this process - nameiexec(p, ndp) */ 610 bzero(p->p_comm, sizeof(p->p_comm)); 611 if (args->fname) 612 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 613 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 614 else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0) 615 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 616 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 617 618 /* 619 * mark as execed, wakeup the process that vforked (if any) and tell 620 * it that it now has its own resources back 621 */ 622 p->p_flag |= P_EXEC; 623 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 624 p->p_flag &= ~P_PPWAIT; 625 cv_broadcast(&p->p_pwait); 626 } 627 628 /* 629 * Implement image setuid/setgid. 630 * 631 * Don't honor setuid/setgid if the filesystem prohibits it or if 632 * the process is being traced. 633 * 634 * XXXMAC: For the time being, use NOSUID to also prohibit 635 * transitions on the file system. 636 */ 637 credential_changing = 0; 638 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 639 attr.va_uid; 640 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 641 attr.va_gid; 642 #ifdef MAC 643 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 644 interpvplabel, imgp); 645 credential_changing |= will_transition; 646 #endif 647 648 if (credential_changing && 649 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 650 (p->p_flag & P_TRACED) == 0) { 651 /* 652 * Turn off syscall tracing for set-id programs, except for 653 * root. Record any set-id flags first to make sure that 654 * we do not regain any tracing during a possible block. 655 */ 656 setsugid(p); 657 658 #ifdef KTRACE 659 if (priv_check_cred(oldcred, PRIV_DEBUG_DIFFCRED, 0)) 660 ktrprocexec(p, &tracecred, &tracevp); 661 #endif 662 /* 663 * Close any file descriptors 0..2 that reference procfs, 664 * then make sure file descriptors 0..2 are in use. 665 * 666 * setugidsafety() may call closef() and then pfind() 667 * which may grab the process lock. 668 * fdcheckstd() may call falloc() which may block to 669 * allocate memory, so temporarily drop the process lock. 670 */ 671 PROC_UNLOCK(p); 672 VOP_UNLOCK(imgp->vp, 0); 673 setugidsafety(td); 674 error = fdcheckstd(td); 675 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 676 if (error != 0) 677 goto done1; 678 PROC_LOCK(p); 679 /* 680 * Set the new credentials. 681 */ 682 if (attr.va_mode & S_ISUID) 683 change_euid(newcred, euip); 684 if (attr.va_mode & S_ISGID) 685 change_egid(newcred, attr.va_gid); 686 #ifdef MAC 687 if (will_transition) { 688 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 689 interpvplabel, imgp); 690 } 691 #endif 692 /* 693 * Implement correct POSIX saved-id behavior. 694 * 695 * XXXMAC: Note that the current logic will save the 696 * uid and gid if a MAC domain transition occurs, even 697 * though maybe it shouldn't. 698 */ 699 change_svuid(newcred, newcred->cr_uid); 700 change_svgid(newcred, newcred->cr_gid); 701 p->p_ucred = newcred; 702 newcred = NULL; 703 } else { 704 if (oldcred->cr_uid == oldcred->cr_ruid && 705 oldcred->cr_gid == oldcred->cr_rgid) 706 p->p_flag &= ~P_SUGID; 707 /* 708 * Implement correct POSIX saved-id behavior. 709 * 710 * XXX: It's not clear that the existing behavior is 711 * POSIX-compliant. A number of sources indicate that the 712 * saved uid/gid should only be updated if the new ruid is 713 * not equal to the old ruid, or the new euid is not equal 714 * to the old euid and the new euid is not equal to the old 715 * ruid. The FreeBSD code always updates the saved uid/gid. 716 * Also, this code uses the new (replaced) euid and egid as 717 * the source, which may or may not be the right ones to use. 718 */ 719 if (oldcred->cr_svuid != oldcred->cr_uid || 720 oldcred->cr_svgid != oldcred->cr_gid) { 721 change_svuid(newcred, newcred->cr_uid); 722 change_svgid(newcred, newcred->cr_gid); 723 p->p_ucred = newcred; 724 newcred = NULL; 725 } 726 } 727 728 /* 729 * Store the vp for use in procfs. This vnode was referenced prior 730 * to locking the proc lock. 731 */ 732 textvp = p->p_textvp; 733 p->p_textvp = binvp; 734 735 #ifdef KDTRACE_HOOKS 736 /* 737 * Tell the DTrace fasttrap provider about the exec if it 738 * has declared an interest. 739 */ 740 if (dtrace_fasttrap_exec) 741 dtrace_fasttrap_exec(p); 742 #endif 743 744 /* 745 * Notify others that we exec'd, and clear the P_INEXEC flag 746 * as we're now a bona fide freshly-execed process. 747 */ 748 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 749 p->p_flag &= ~P_INEXEC; 750 751 /* 752 * If tracing the process, trap to the debugger so that 753 * breakpoints can be set before the program executes. We 754 * have to use tdsignal() to deliver the signal to the current 755 * thread since any other threads in this process will exit if 756 * execve() succeeds. 757 */ 758 if (p->p_flag & P_TRACED) 759 tdsignal(td, SIGTRAP); 760 761 /* clear "fork but no exec" flag, as we _are_ execing */ 762 p->p_acflag &= ~AFORK; 763 764 /* 765 * Free any previous argument cache and replace it with 766 * the new argument cache, if any. 767 */ 768 oldargs = p->p_args; 769 p->p_args = newargs; 770 newargs = NULL; 771 772 #ifdef HWPMC_HOOKS 773 /* 774 * Check if system-wide sampling is in effect or if the 775 * current process is using PMCs. If so, do exec() time 776 * processing. This processing needs to happen AFTER the 777 * P_INEXEC flag is cleared. 778 * 779 * The proc lock needs to be released before taking the PMC 780 * SX. 781 */ 782 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 783 PROC_UNLOCK(p); 784 VOP_UNLOCK(imgp->vp, 0); 785 pe.pm_credentialschanged = credential_changing; 786 pe.pm_entryaddr = imgp->entry_addr; 787 788 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 789 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 790 } else 791 PROC_UNLOCK(p); 792 #else /* !HWPMC_HOOKS */ 793 PROC_UNLOCK(p); 794 #endif 795 796 /* Set values passed into the program in registers. */ 797 if (p->p_sysent->sv_setregs) 798 (*p->p_sysent->sv_setregs)(td, imgp, 799 (u_long)(uintptr_t)stack_base); 800 else 801 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 802 803 vfs_mark_atime(imgp->vp, td->td_ucred); 804 805 SDT_PROBE(proc, kernel, , exec_success, args->fname, 0, 0, 0, 0); 806 807 done1: 808 /* 809 * Free any resources malloc'd earlier that we didn't use. 810 */ 811 uifree(euip); 812 if (newcred == NULL) 813 crfree(oldcred); 814 else 815 crfree(newcred); 816 VOP_UNLOCK(imgp->vp, 0); 817 818 /* 819 * Handle deferred decrement of ref counts. 820 */ 821 if (textvp != NULL) { 822 int tvfslocked; 823 824 tvfslocked = VFS_LOCK_GIANT(textvp->v_mount); 825 vrele(textvp); 826 VFS_UNLOCK_GIANT(tvfslocked); 827 } 828 if (binvp && error != 0) 829 vrele(binvp); 830 #ifdef KTRACE 831 if (tracevp != NULL) { 832 int tvfslocked; 833 834 tvfslocked = VFS_LOCK_GIANT(tracevp->v_mount); 835 vrele(tracevp); 836 VFS_UNLOCK_GIANT(tvfslocked); 837 } 838 if (tracecred != NULL) 839 crfree(tracecred); 840 #endif 841 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 842 pargs_drop(oldargs); 843 pargs_drop(newargs); 844 if (oldsigacts != NULL) 845 sigacts_free(oldsigacts); 846 847 exec_fail_dealloc: 848 849 /* 850 * free various allocated resources 851 */ 852 if (imgp->firstpage != NULL) 853 exec_unmap_first_page(imgp); 854 855 if (imgp->vp != NULL) { 856 if (args->fname) 857 NDFREE(&nd, NDF_ONLY_PNBUF); 858 if (imgp->opened) 859 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 860 vput(imgp->vp); 861 } 862 863 if (imgp->object != NULL) 864 vm_object_deallocate(imgp->object); 865 866 free(imgp->freepath, M_TEMP); 867 868 if (error == 0) { 869 PROC_LOCK(p); 870 td->td_dbgflags |= TDB_EXEC; 871 PROC_UNLOCK(p); 872 873 /* 874 * Stop the process here if its stop event mask has 875 * the S_EXEC bit set. 876 */ 877 STOPEVENT(p, S_EXEC, 0); 878 goto done2; 879 } 880 881 exec_fail: 882 /* we're done here, clear P_INEXEC */ 883 PROC_LOCK(p); 884 p->p_flag &= ~P_INEXEC; 885 PROC_UNLOCK(p); 886 887 SDT_PROBE(proc, kernel, , exec_failure, error, 0, 0, 0, 0); 888 889 done2: 890 #ifdef MAC 891 mac_execve_exit(imgp); 892 mac_execve_interpreter_exit(interpvplabel); 893 #endif 894 VFS_UNLOCK_GIANT(vfslocked); 895 exec_free_args(args); 896 897 if (error && imgp->vmspace_destroyed) { 898 /* sorry, no more process anymore. exit gracefully */ 899 exit1(td, W_EXITCODE(0, SIGABRT)); 900 /* NOT REACHED */ 901 } 902 903 #ifdef KTRACE 904 if (error == 0) 905 ktrprocctor(p); 906 #endif 907 908 return (error); 909 } 910 911 int 912 exec_map_first_page(imgp) 913 struct image_params *imgp; 914 { 915 int rv, i; 916 int initial_pagein; 917 vm_page_t ma[VM_INITIAL_PAGEIN]; 918 vm_object_t object; 919 920 if (imgp->firstpage != NULL) 921 exec_unmap_first_page(imgp); 922 923 object = imgp->vp->v_object; 924 if (object == NULL) 925 return (EACCES); 926 VM_OBJECT_LOCK(object); 927 #if VM_NRESERVLEVEL > 0 928 if ((object->flags & OBJ_COLORED) == 0) { 929 object->flags |= OBJ_COLORED; 930 object->pg_color = 0; 931 } 932 #endif 933 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 934 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 935 initial_pagein = VM_INITIAL_PAGEIN; 936 if (initial_pagein > object->size) 937 initial_pagein = object->size; 938 for (i = 1; i < initial_pagein; i++) { 939 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 940 if (ma[i]->valid) 941 break; 942 if ((ma[i]->oflags & VPO_BUSY) || ma[i]->busy) 943 break; 944 vm_page_busy(ma[i]); 945 } else { 946 ma[i] = vm_page_alloc(object, i, 947 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 948 if (ma[i] == NULL) 949 break; 950 } 951 } 952 initial_pagein = i; 953 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 954 ma[0] = vm_page_lookup(object, 0); 955 if ((rv != VM_PAGER_OK) || (ma[0] == NULL)) { 956 if (ma[0] != NULL) { 957 vm_page_lock(ma[0]); 958 vm_page_free(ma[0]); 959 vm_page_unlock(ma[0]); 960 } 961 VM_OBJECT_UNLOCK(object); 962 return (EIO); 963 } 964 } 965 vm_page_lock(ma[0]); 966 vm_page_hold(ma[0]); 967 vm_page_unlock(ma[0]); 968 vm_page_wakeup(ma[0]); 969 VM_OBJECT_UNLOCK(object); 970 971 imgp->firstpage = sf_buf_alloc(ma[0], 0); 972 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 973 974 return (0); 975 } 976 977 void 978 exec_unmap_first_page(imgp) 979 struct image_params *imgp; 980 { 981 vm_page_t m; 982 983 if (imgp->firstpage != NULL) { 984 m = sf_buf_page(imgp->firstpage); 985 sf_buf_free(imgp->firstpage); 986 imgp->firstpage = NULL; 987 vm_page_lock(m); 988 vm_page_unhold(m); 989 vm_page_unlock(m); 990 } 991 } 992 993 /* 994 * Destroy old address space, and allocate a new stack 995 * The new stack is only SGROWSIZ large because it is grown 996 * automatically in trap.c. 997 */ 998 int 999 exec_new_vmspace(imgp, sv) 1000 struct image_params *imgp; 1001 struct sysentvec *sv; 1002 { 1003 int error; 1004 struct proc *p = imgp->proc; 1005 struct vmspace *vmspace = p->p_vmspace; 1006 vm_object_t obj; 1007 vm_offset_t sv_minuser, stack_addr; 1008 vm_map_t map; 1009 u_long ssiz; 1010 1011 imgp->vmspace_destroyed = 1; 1012 imgp->sysent = sv; 1013 1014 /* May be called with Giant held */ 1015 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1016 1017 /* 1018 * Blow away entire process VM, if address space not shared, 1019 * otherwise, create a new VM space so that other threads are 1020 * not disrupted 1021 */ 1022 map = &vmspace->vm_map; 1023 if (map_at_zero) 1024 sv_minuser = sv->sv_minuser; 1025 else 1026 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1027 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1028 vm_map_max(map) == sv->sv_maxuser) { 1029 shmexit(vmspace); 1030 pmap_remove_pages(vmspace_pmap(vmspace)); 1031 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1032 } else { 1033 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1034 if (error) 1035 return (error); 1036 vmspace = p->p_vmspace; 1037 map = &vmspace->vm_map; 1038 } 1039 1040 /* Map a shared page */ 1041 obj = sv->sv_shared_page_obj; 1042 if (obj != NULL) { 1043 vm_object_reference(obj); 1044 error = vm_map_fixed(map, obj, 0, 1045 sv->sv_shared_page_base, sv->sv_shared_page_len, 1046 VM_PROT_READ | VM_PROT_EXECUTE, VM_PROT_ALL, 1047 MAP_COPY_ON_WRITE | MAP_ACC_NO_CHARGE); 1048 if (error) { 1049 vm_object_deallocate(obj); 1050 return (error); 1051 } 1052 } 1053 1054 /* Allocate a new stack */ 1055 if (sv->sv_maxssiz != NULL) 1056 ssiz = *sv->sv_maxssiz; 1057 else 1058 ssiz = maxssiz; 1059 stack_addr = sv->sv_usrstack - ssiz; 1060 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1061 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1062 sv->sv_stackprot, 1063 VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1064 if (error) 1065 return (error); 1066 1067 #ifdef __ia64__ 1068 /* Allocate a new register stack */ 1069 stack_addr = IA64_BACKINGSTORE; 1070 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1071 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP); 1072 if (error) 1073 return (error); 1074 #endif 1075 1076 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 1077 * VM_STACK case, but they are still used to monitor the size of the 1078 * process stack so we can check the stack rlimit. 1079 */ 1080 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1081 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1082 1083 return (0); 1084 } 1085 1086 /* 1087 * Copy out argument and environment strings from the old process address 1088 * space into the temporary string buffer. 1089 */ 1090 int 1091 exec_copyin_args(struct image_args *args, char *fname, 1092 enum uio_seg segflg, char **argv, char **envv) 1093 { 1094 char *argp, *envp; 1095 int error; 1096 size_t length; 1097 1098 bzero(args, sizeof(*args)); 1099 if (argv == NULL) 1100 return (EFAULT); 1101 1102 /* 1103 * Allocate demand-paged memory for the file name, argument, and 1104 * environment strings. 1105 */ 1106 error = exec_alloc_args(args); 1107 if (error != 0) 1108 return (error); 1109 1110 /* 1111 * Copy the file name. 1112 */ 1113 if (fname != NULL) { 1114 args->fname = args->buf; 1115 error = (segflg == UIO_SYSSPACE) ? 1116 copystr(fname, args->fname, PATH_MAX, &length) : 1117 copyinstr(fname, args->fname, PATH_MAX, &length); 1118 if (error != 0) 1119 goto err_exit; 1120 } else 1121 length = 0; 1122 1123 args->begin_argv = args->buf + length; 1124 args->endp = args->begin_argv; 1125 args->stringspace = ARG_MAX; 1126 1127 /* 1128 * extract arguments first 1129 */ 1130 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 1131 if (argp == (caddr_t) -1) { 1132 error = EFAULT; 1133 goto err_exit; 1134 } 1135 if ((error = copyinstr(argp, args->endp, 1136 args->stringspace, &length))) { 1137 if (error == ENAMETOOLONG) 1138 error = E2BIG; 1139 goto err_exit; 1140 } 1141 args->stringspace -= length; 1142 args->endp += length; 1143 args->argc++; 1144 } 1145 1146 args->begin_envv = args->endp; 1147 1148 /* 1149 * extract environment strings 1150 */ 1151 if (envv) { 1152 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) { 1153 if (envp == (caddr_t)-1) { 1154 error = EFAULT; 1155 goto err_exit; 1156 } 1157 if ((error = copyinstr(envp, args->endp, 1158 args->stringspace, &length))) { 1159 if (error == ENAMETOOLONG) 1160 error = E2BIG; 1161 goto err_exit; 1162 } 1163 args->stringspace -= length; 1164 args->endp += length; 1165 args->envc++; 1166 } 1167 } 1168 1169 return (0); 1170 1171 err_exit: 1172 exec_free_args(args); 1173 return (error); 1174 } 1175 1176 /* 1177 * Allocate temporary demand-paged, zero-filled memory for the file name, 1178 * argument, and environment strings. Returns zero if the allocation succeeds 1179 * and ENOMEM otherwise. 1180 */ 1181 int 1182 exec_alloc_args(struct image_args *args) 1183 { 1184 1185 args->buf = (char *)kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 1186 return (args->buf != NULL ? 0 : ENOMEM); 1187 } 1188 1189 void 1190 exec_free_args(struct image_args *args) 1191 { 1192 1193 if (args->buf != NULL) { 1194 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf, 1195 PATH_MAX + ARG_MAX); 1196 args->buf = NULL; 1197 } 1198 if (args->fname_buf != NULL) { 1199 free(args->fname_buf, M_TEMP); 1200 args->fname_buf = NULL; 1201 } 1202 } 1203 1204 /* 1205 * Copy strings out to the new process address space, constructing new arg 1206 * and env vector tables. Return a pointer to the base so that it can be used 1207 * as the initial stack pointer. 1208 */ 1209 register_t * 1210 exec_copyout_strings(imgp) 1211 struct image_params *imgp; 1212 { 1213 int argc, envc; 1214 char **vectp; 1215 char *stringp, *destp; 1216 register_t *stack_base; 1217 struct ps_strings *arginfo; 1218 struct proc *p; 1219 size_t execpath_len; 1220 int szsigcode, szps; 1221 char canary[sizeof(long) * 8]; 1222 1223 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1224 /* 1225 * Calculate string base and vector table pointers. 1226 * Also deal with signal trampoline code for this exec type. 1227 */ 1228 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1229 execpath_len = strlen(imgp->execpath) + 1; 1230 else 1231 execpath_len = 0; 1232 p = imgp->proc; 1233 szsigcode = 0; 1234 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1235 if (p->p_sysent->sv_sigcode_base == 0) { 1236 if (p->p_sysent->sv_szsigcode != NULL) 1237 szsigcode = *(p->p_sysent->sv_szsigcode); 1238 } 1239 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 1240 roundup(execpath_len, sizeof(char *)) - 1241 roundup(sizeof(canary), sizeof(char *)) - 1242 roundup(szps, sizeof(char *)) - 1243 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *)); 1244 1245 /* 1246 * install sigcode 1247 */ 1248 if (szsigcode != 0) 1249 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo - 1250 szsigcode), szsigcode); 1251 1252 /* 1253 * Copy the image path for the rtld. 1254 */ 1255 if (execpath_len != 0) { 1256 imgp->execpathp = (uintptr_t)arginfo - szsigcode - execpath_len; 1257 copyout(imgp->execpath, (void *)imgp->execpathp, 1258 execpath_len); 1259 } 1260 1261 /* 1262 * Prepare the canary for SSP. 1263 */ 1264 arc4rand(canary, sizeof(canary), 0); 1265 imgp->canary = (uintptr_t)arginfo - szsigcode - execpath_len - 1266 sizeof(canary); 1267 copyout(canary, (void *)imgp->canary, sizeof(canary)); 1268 imgp->canarylen = sizeof(canary); 1269 1270 /* 1271 * Prepare the pagesizes array. 1272 */ 1273 imgp->pagesizes = (uintptr_t)arginfo - szsigcode - execpath_len - 1274 roundup(sizeof(canary), sizeof(char *)) - szps; 1275 copyout(pagesizes, (void *)imgp->pagesizes, szps); 1276 imgp->pagesizeslen = szps; 1277 1278 /* 1279 * If we have a valid auxargs ptr, prepare some room 1280 * on the stack. 1281 */ 1282 if (imgp->auxargs) { 1283 /* 1284 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1285 * lower compatibility. 1286 */ 1287 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1288 (AT_COUNT * 2); 1289 /* 1290 * The '+ 2' is for the null pointers at the end of each of 1291 * the arg and env vector sets,and imgp->auxarg_size is room 1292 * for argument of Runtime loader. 1293 */ 1294 vectp = (char **)(destp - (imgp->args->argc + 1295 imgp->args->envc + 2 + imgp->auxarg_size) 1296 * sizeof(char *)); 1297 } else { 1298 /* 1299 * The '+ 2' is for the null pointers at the end of each of 1300 * the arg and env vector sets 1301 */ 1302 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) * 1303 sizeof(char *)); 1304 } 1305 1306 /* 1307 * vectp also becomes our initial stack base 1308 */ 1309 stack_base = (register_t *)vectp; 1310 1311 stringp = imgp->args->begin_argv; 1312 argc = imgp->args->argc; 1313 envc = imgp->args->envc; 1314 1315 /* 1316 * Copy out strings - arguments and environment. 1317 */ 1318 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace); 1319 1320 /* 1321 * Fill in "ps_strings" struct for ps, w, etc. 1322 */ 1323 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1324 suword32(&arginfo->ps_nargvstr, argc); 1325 1326 /* 1327 * Fill in argument portion of vector table. 1328 */ 1329 for (; argc > 0; --argc) { 1330 suword(vectp++, (long)(intptr_t)destp); 1331 while (*stringp++ != 0) 1332 destp++; 1333 destp++; 1334 } 1335 1336 /* a null vector table pointer separates the argp's from the envp's */ 1337 suword(vectp++, 0); 1338 1339 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1340 suword32(&arginfo->ps_nenvstr, envc); 1341 1342 /* 1343 * Fill in environment portion of vector table. 1344 */ 1345 for (; envc > 0; --envc) { 1346 suword(vectp++, (long)(intptr_t)destp); 1347 while (*stringp++ != 0) 1348 destp++; 1349 destp++; 1350 } 1351 1352 /* end of vector table is a null pointer */ 1353 suword(vectp, 0); 1354 1355 return (stack_base); 1356 } 1357 1358 /* 1359 * Check permissions of file to execute. 1360 * Called with imgp->vp locked. 1361 * Return 0 for success or error code on failure. 1362 */ 1363 int 1364 exec_check_permissions(imgp) 1365 struct image_params *imgp; 1366 { 1367 struct vnode *vp = imgp->vp; 1368 struct vattr *attr = imgp->attr; 1369 struct thread *td; 1370 int error; 1371 1372 td = curthread; 1373 1374 /* Get file attributes */ 1375 error = VOP_GETATTR(vp, attr, td->td_ucred); 1376 if (error) 1377 return (error); 1378 1379 #ifdef MAC 1380 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1381 if (error) 1382 return (error); 1383 #endif 1384 1385 /* 1386 * 1) Check if file execution is disabled for the filesystem that 1387 * this file resides on. 1388 * 2) Ensure that at least one execute bit is on. Otherwise, a 1389 * privileged user will always succeed, and we don't want this 1390 * to happen unless the file really is executable. 1391 * 3) Ensure that the file is a regular file. 1392 */ 1393 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1394 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1395 (attr->va_type != VREG)) 1396 return (EACCES); 1397 1398 /* 1399 * Zero length files can't be exec'd 1400 */ 1401 if (attr->va_size == 0) 1402 return (ENOEXEC); 1403 1404 /* 1405 * Check for execute permission to file based on current credentials. 1406 */ 1407 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1408 if (error) 1409 return (error); 1410 1411 /* 1412 * Check number of open-for-writes on the file and deny execution 1413 * if there are any. 1414 */ 1415 if (vp->v_writecount) 1416 return (ETXTBSY); 1417 1418 /* 1419 * Call filesystem specific open routine (which does nothing in the 1420 * general case). 1421 */ 1422 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1423 if (error == 0) 1424 imgp->opened = 1; 1425 return (error); 1426 } 1427 1428 /* 1429 * Exec handler registration 1430 */ 1431 int 1432 exec_register(execsw_arg) 1433 const struct execsw *execsw_arg; 1434 { 1435 const struct execsw **es, **xs, **newexecsw; 1436 int count = 2; /* New slot and trailing NULL */ 1437 1438 if (execsw) 1439 for (es = execsw; *es; es++) 1440 count++; 1441 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1442 if (newexecsw == NULL) 1443 return (ENOMEM); 1444 xs = newexecsw; 1445 if (execsw) 1446 for (es = execsw; *es; es++) 1447 *xs++ = *es; 1448 *xs++ = execsw_arg; 1449 *xs = NULL; 1450 if (execsw) 1451 free(execsw, M_TEMP); 1452 execsw = newexecsw; 1453 return (0); 1454 } 1455 1456 int 1457 exec_unregister(execsw_arg) 1458 const struct execsw *execsw_arg; 1459 { 1460 const struct execsw **es, **xs, **newexecsw; 1461 int count = 1; 1462 1463 if (execsw == NULL) 1464 panic("unregister with no handlers left?\n"); 1465 1466 for (es = execsw; *es; es++) { 1467 if (*es == execsw_arg) 1468 break; 1469 } 1470 if (*es == NULL) 1471 return (ENOENT); 1472 for (es = execsw; *es; es++) 1473 if (*es != execsw_arg) 1474 count++; 1475 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1476 if (newexecsw == NULL) 1477 return (ENOMEM); 1478 xs = newexecsw; 1479 for (es = execsw; *es; es++) 1480 if (*es != execsw_arg) 1481 *xs++ = *es; 1482 *xs = NULL; 1483 if (execsw) 1484 free(execsw, M_TEMP); 1485 execsw = newexecsw; 1486 return (0); 1487 } 1488 1489 static vm_object_t shared_page_obj; 1490 static int shared_page_free; 1491 1492 int 1493 shared_page_fill(int size, int align, const char *data) 1494 { 1495 vm_page_t m; 1496 struct sf_buf *s; 1497 vm_offset_t sk; 1498 int res; 1499 1500 VM_OBJECT_LOCK(shared_page_obj); 1501 m = vm_page_grab(shared_page_obj, 0, VM_ALLOC_RETRY); 1502 res = roundup(shared_page_free, align); 1503 if (res + size >= IDX_TO_OFF(shared_page_obj->size)) 1504 res = -1; 1505 else { 1506 VM_OBJECT_UNLOCK(shared_page_obj); 1507 s = sf_buf_alloc(m, SFB_DEFAULT); 1508 sk = sf_buf_kva(s); 1509 bcopy(data, (void *)(sk + res), size); 1510 shared_page_free = res + size; 1511 sf_buf_free(s); 1512 VM_OBJECT_LOCK(shared_page_obj); 1513 } 1514 vm_page_wakeup(m); 1515 VM_OBJECT_UNLOCK(shared_page_obj); 1516 return (res); 1517 } 1518 1519 static void 1520 shared_page_init(void *dummy __unused) 1521 { 1522 vm_page_t m; 1523 1524 shared_page_obj = vm_pager_allocate(OBJT_PHYS, 0, PAGE_SIZE, 1525 VM_PROT_DEFAULT, 0, NULL); 1526 VM_OBJECT_LOCK(shared_page_obj); 1527 m = vm_page_grab(shared_page_obj, 0, VM_ALLOC_RETRY | VM_ALLOC_NOBUSY | 1528 VM_ALLOC_ZERO); 1529 m->valid = VM_PAGE_BITS_ALL; 1530 VM_OBJECT_UNLOCK(shared_page_obj); 1531 } 1532 1533 SYSINIT(shp, SI_SUB_EXEC, SI_ORDER_FIRST, (sysinit_cfunc_t)shared_page_init, 1534 NULL); 1535 1536 void 1537 exec_sysvec_init(void *param) 1538 { 1539 struct sysentvec *sv; 1540 1541 sv = (struct sysentvec *)param; 1542 1543 if ((sv->sv_flags & SV_SHP) == 0) 1544 return; 1545 sv->sv_shared_page_obj = shared_page_obj; 1546 sv->sv_sigcode_base = sv->sv_shared_page_base + 1547 shared_page_fill(*(sv->sv_szsigcode), 16, sv->sv_sigcode); 1548 } 1549