1 /*- 2 * Copyright (c) 1993, David Greenman 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 #include "opt_capsicum.h" 31 #include "opt_hwpmc_hooks.h" 32 #include "opt_ktrace.h" 33 #include "opt_vm.h" 34 35 #include <sys/param.h> 36 #include <sys/capsicum.h> 37 #include <sys/systm.h> 38 #include <sys/eventhandler.h> 39 #include <sys/lock.h> 40 #include <sys/mutex.h> 41 #include <sys/sysproto.h> 42 #include <sys/signalvar.h> 43 #include <sys/kernel.h> 44 #include <sys/mount.h> 45 #include <sys/filedesc.h> 46 #include <sys/fcntl.h> 47 #include <sys/acct.h> 48 #include <sys/exec.h> 49 #include <sys/imgact.h> 50 #include <sys/imgact_elf.h> 51 #include <sys/wait.h> 52 #include <sys/malloc.h> 53 #include <sys/priv.h> 54 #include <sys/proc.h> 55 #include <sys/pioctl.h> 56 #include <sys/namei.h> 57 #include <sys/resourcevar.h> 58 #include <sys/rwlock.h> 59 #include <sys/sched.h> 60 #include <sys/sdt.h> 61 #include <sys/sf_buf.h> 62 #include <sys/syscallsubr.h> 63 #include <sys/sysent.h> 64 #include <sys/shm.h> 65 #include <sys/sysctl.h> 66 #include <sys/vnode.h> 67 #include <sys/stat.h> 68 #ifdef KTRACE 69 #include <sys/ktrace.h> 70 #endif 71 72 #include <vm/vm.h> 73 #include <vm/vm_param.h> 74 #include <vm/pmap.h> 75 #include <vm/vm_page.h> 76 #include <vm/vm_map.h> 77 #include <vm/vm_kern.h> 78 #include <vm/vm_extern.h> 79 #include <vm/vm_object.h> 80 #include <vm/vm_pager.h> 81 82 #ifdef HWPMC_HOOKS 83 #include <sys/pmckern.h> 84 #endif 85 86 #include <machine/reg.h> 87 88 #include <security/audit/audit.h> 89 #include <security/mac/mac_framework.h> 90 91 #ifdef KDTRACE_HOOKS 92 #include <sys/dtrace_bsd.h> 93 dtrace_execexit_func_t dtrace_fasttrap_exec; 94 #endif 95 96 SDT_PROVIDER_DECLARE(proc); 97 SDT_PROBE_DEFINE1(proc, kernel, , exec, "char *"); 98 SDT_PROBE_DEFINE1(proc, kernel, , exec__failure, "int"); 99 SDT_PROBE_DEFINE1(proc, kernel, , exec__success, "char *"); 100 101 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 102 103 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 104 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 105 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 106 static int do_execve(struct thread *td, struct image_args *args, 107 struct mac *mac_p); 108 109 /* XXX This should be vm_size_t. */ 110 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD, 111 NULL, 0, sysctl_kern_ps_strings, "LU", ""); 112 113 /* XXX This should be vm_size_t. */ 114 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 115 CTLFLAG_CAPRD, NULL, 0, sysctl_kern_usrstack, "LU", ""); 116 117 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 118 NULL, 0, sysctl_kern_stackprot, "I", ""); 119 120 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 121 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 122 &ps_arg_cache_limit, 0, ""); 123 124 static int disallow_high_osrel; 125 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW, 126 &disallow_high_osrel, 0, 127 "Disallow execution of binaries built for higher version of the world"); 128 129 static int map_at_zero = 0; 130 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RWTUN, &map_at_zero, 0, 131 "Permit processes to map an object at virtual address 0."); 132 133 static int 134 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 135 { 136 struct proc *p; 137 int error; 138 139 p = curproc; 140 #ifdef SCTL_MASK32 141 if (req->flags & SCTL_MASK32) { 142 unsigned int val; 143 val = (unsigned int)p->p_sysent->sv_psstrings; 144 error = SYSCTL_OUT(req, &val, sizeof(val)); 145 } else 146 #endif 147 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 148 sizeof(p->p_sysent->sv_psstrings)); 149 return error; 150 } 151 152 static int 153 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 154 { 155 struct proc *p; 156 int error; 157 158 p = curproc; 159 #ifdef SCTL_MASK32 160 if (req->flags & SCTL_MASK32) { 161 unsigned int val; 162 val = (unsigned int)p->p_sysent->sv_usrstack; 163 error = SYSCTL_OUT(req, &val, sizeof(val)); 164 } else 165 #endif 166 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 167 sizeof(p->p_sysent->sv_usrstack)); 168 return error; 169 } 170 171 static int 172 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 173 { 174 struct proc *p; 175 176 p = curproc; 177 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 178 sizeof(p->p_sysent->sv_stackprot))); 179 } 180 181 /* 182 * Each of the items is a pointer to a `const struct execsw', hence the 183 * double pointer here. 184 */ 185 static const struct execsw **execsw; 186 187 #ifndef _SYS_SYSPROTO_H_ 188 struct execve_args { 189 char *fname; 190 char **argv; 191 char **envv; 192 }; 193 #endif 194 195 int 196 sys_execve(struct thread *td, struct execve_args *uap) 197 { 198 struct image_args args; 199 struct vmspace *oldvmspace; 200 int error; 201 202 error = pre_execve(td, &oldvmspace); 203 if (error != 0) 204 return (error); 205 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 206 uap->argv, uap->envv); 207 if (error == 0) 208 error = kern_execve(td, &args, NULL); 209 post_execve(td, error, oldvmspace); 210 return (error); 211 } 212 213 #ifndef _SYS_SYSPROTO_H_ 214 struct fexecve_args { 215 int fd; 216 char **argv; 217 char **envv; 218 } 219 #endif 220 int 221 sys_fexecve(struct thread *td, struct fexecve_args *uap) 222 { 223 struct image_args args; 224 struct vmspace *oldvmspace; 225 int error; 226 227 error = pre_execve(td, &oldvmspace); 228 if (error != 0) 229 return (error); 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 post_execve(td, error, oldvmspace); 237 return (error); 238 } 239 240 #ifndef _SYS_SYSPROTO_H_ 241 struct __mac_execve_args { 242 char *fname; 243 char **argv; 244 char **envv; 245 struct mac *mac_p; 246 }; 247 #endif 248 249 int 250 sys___mac_execve(struct thread *td, struct __mac_execve_args *uap) 251 { 252 #ifdef MAC 253 struct image_args args; 254 struct vmspace *oldvmspace; 255 int error; 256 257 error = pre_execve(td, &oldvmspace); 258 if (error != 0) 259 return (error); 260 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 261 uap->argv, uap->envv); 262 if (error == 0) 263 error = kern_execve(td, &args, uap->mac_p); 264 post_execve(td, error, oldvmspace); 265 return (error); 266 #else 267 return (ENOSYS); 268 #endif 269 } 270 271 int 272 pre_execve(struct thread *td, struct vmspace **oldvmspace) 273 { 274 struct proc *p; 275 int error; 276 277 KASSERT(td == curthread, ("non-current thread %p", td)); 278 error = 0; 279 p = td->td_proc; 280 if ((p->p_flag & P_HADTHREADS) != 0) { 281 PROC_LOCK(p); 282 if (thread_single(p, SINGLE_BOUNDARY) != 0) 283 error = ERESTART; 284 PROC_UNLOCK(p); 285 } 286 KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0, 287 ("nested execve")); 288 *oldvmspace = p->p_vmspace; 289 return (error); 290 } 291 292 void 293 post_execve(struct thread *td, int error, struct vmspace *oldvmspace) 294 { 295 struct proc *p; 296 297 KASSERT(td == curthread, ("non-current thread %p", td)); 298 p = td->td_proc; 299 if ((p->p_flag & P_HADTHREADS) != 0) { 300 PROC_LOCK(p); 301 /* 302 * If success, we upgrade to SINGLE_EXIT state to 303 * force other threads to suicide. 304 */ 305 if (error == 0) 306 thread_single(p, SINGLE_EXIT); 307 else 308 thread_single_end(p, SINGLE_BOUNDARY); 309 PROC_UNLOCK(p); 310 } 311 if ((td->td_pflags & TDP_EXECVMSPC) != 0) { 312 KASSERT(p->p_vmspace != oldvmspace, 313 ("oldvmspace still used")); 314 vmspace_free(oldvmspace); 315 td->td_pflags &= ~TDP_EXECVMSPC; 316 } 317 } 318 319 /* 320 * XXX: kern_execve has the astonishing property of not always returning to 321 * the caller. If sufficiently bad things happen during the call to 322 * do_execve(), it can end up calling exit1(); as a result, callers must 323 * avoid doing anything which they might need to undo (e.g., allocating 324 * memory). 325 */ 326 int 327 kern_execve(struct thread *td, struct image_args *args, struct mac *mac_p) 328 { 329 330 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 331 args->begin_envv - args->begin_argv); 332 AUDIT_ARG_ENVV(args->begin_envv, args->envc, 333 args->endp - args->begin_envv); 334 return (do_execve(td, args, mac_p)); 335 } 336 337 /* 338 * In-kernel implementation of execve(). All arguments are assumed to be 339 * userspace pointers from the passed thread. 340 */ 341 static int 342 do_execve(td, args, mac_p) 343 struct thread *td; 344 struct image_args *args; 345 struct mac *mac_p; 346 { 347 struct proc *p = td->td_proc; 348 struct nameidata nd; 349 struct ucred *newcred = NULL, *oldcred; 350 struct uidinfo *euip = NULL; 351 register_t *stack_base; 352 int error, i; 353 struct image_params image_params, *imgp; 354 struct vattr attr; 355 int (*img_first)(struct image_params *); 356 struct pargs *oldargs = NULL, *newargs = NULL; 357 struct sigacts *oldsigacts, *newsigacts; 358 #ifdef KTRACE 359 struct vnode *tracevp = NULL; 360 struct ucred *tracecred = NULL; 361 #endif 362 struct vnode *textvp = NULL, *binvp; 363 cap_rights_t rights; 364 int credential_changing; 365 int textset; 366 #ifdef MAC 367 struct label *interpvplabel = NULL; 368 int will_transition; 369 #endif 370 #ifdef HWPMC_HOOKS 371 struct pmckern_procexec pe; 372 #endif 373 static const char fexecv_proc_title[] = "(fexecv)"; 374 375 imgp = &image_params; 376 377 /* 378 * Lock the process and set the P_INEXEC flag to indicate that 379 * it should be left alone until we're done here. This is 380 * necessary to avoid race conditions - e.g. in ptrace() - 381 * that might allow a local user to illicitly obtain elevated 382 * privileges. 383 */ 384 PROC_LOCK(p); 385 KASSERT((p->p_flag & P_INEXEC) == 0, 386 ("%s(): process already has P_INEXEC flag", __func__)); 387 p->p_flag |= P_INEXEC; 388 PROC_UNLOCK(p); 389 390 /* 391 * Initialize part of the common data 392 */ 393 bzero(imgp, sizeof(*imgp)); 394 imgp->proc = p; 395 imgp->attr = &attr; 396 imgp->args = args; 397 398 #ifdef MAC 399 error = mac_execve_enter(imgp, mac_p); 400 if (error) 401 goto exec_fail; 402 #endif 403 404 /* 405 * Translate the file name. namei() returns a vnode pointer 406 * in ni_vp amoung other things. 407 * 408 * XXXAUDIT: It would be desirable to also audit the name of the 409 * interpreter if this is an interpreted binary. 410 */ 411 if (args->fname != NULL) { 412 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 413 | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 414 } 415 416 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 417 418 interpret: 419 if (args->fname != NULL) { 420 #ifdef CAPABILITY_MODE 421 /* 422 * While capability mode can't reach this point via direct 423 * path arguments to execve(), we also don't allow 424 * interpreters to be used in capability mode (for now). 425 * Catch indirect lookups and return a permissions error. 426 */ 427 if (IN_CAPABILITY_MODE(td)) { 428 error = ECAPMODE; 429 goto exec_fail; 430 } 431 #endif 432 error = namei(&nd); 433 if (error) 434 goto exec_fail; 435 436 binvp = nd.ni_vp; 437 imgp->vp = binvp; 438 } else { 439 AUDIT_ARG_FD(args->fd); 440 /* 441 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 442 */ 443 error = fgetvp_exec(td, args->fd, 444 cap_rights_init(&rights, CAP_FEXECVE), &binvp); 445 if (error) 446 goto exec_fail; 447 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY); 448 AUDIT_ARG_VNODE1(binvp); 449 imgp->vp = binvp; 450 } 451 452 /* 453 * Check file permissions (also 'opens' file) 454 */ 455 error = exec_check_permissions(imgp); 456 if (error) 457 goto exec_fail_dealloc; 458 459 imgp->object = imgp->vp->v_object; 460 if (imgp->object != NULL) 461 vm_object_reference(imgp->object); 462 463 /* 464 * Set VV_TEXT now so no one can write to the executable while we're 465 * activating it. 466 * 467 * Remember if this was set before and unset it in case this is not 468 * actually an executable image. 469 */ 470 textset = VOP_IS_TEXT(imgp->vp); 471 VOP_SET_TEXT(imgp->vp); 472 473 error = exec_map_first_page(imgp); 474 if (error) 475 goto exec_fail_dealloc; 476 477 imgp->proc->p_osrel = 0; 478 /* 479 * If the current process has a special image activator it 480 * wants to try first, call it. For example, emulating shell 481 * scripts differently. 482 */ 483 error = -1; 484 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 485 error = img_first(imgp); 486 487 /* 488 * Loop through the list of image activators, calling each one. 489 * An activator returns -1 if there is no match, 0 on success, 490 * and an error otherwise. 491 */ 492 for (i = 0; error == -1 && execsw[i]; ++i) { 493 if (execsw[i]->ex_imgact == NULL || 494 execsw[i]->ex_imgact == img_first) { 495 continue; 496 } 497 error = (*execsw[i]->ex_imgact)(imgp); 498 } 499 500 if (error) { 501 if (error == -1) { 502 if (textset == 0) 503 VOP_UNSET_TEXT(imgp->vp); 504 error = ENOEXEC; 505 } 506 goto exec_fail_dealloc; 507 } 508 509 /* 510 * Special interpreter operation, cleanup and loop up to try to 511 * activate the interpreter. 512 */ 513 if (imgp->interpreted) { 514 exec_unmap_first_page(imgp); 515 /* 516 * VV_TEXT needs to be unset for scripts. There is a short 517 * period before we determine that something is a script where 518 * VV_TEXT will be set. The vnode lock is held over this 519 * entire period so nothing should illegitimately be blocked. 520 */ 521 VOP_UNSET_TEXT(imgp->vp); 522 /* free name buffer and old vnode */ 523 if (args->fname != NULL) 524 NDFREE(&nd, NDF_ONLY_PNBUF); 525 #ifdef MAC 526 mac_execve_interpreter_enter(binvp, &interpvplabel); 527 #endif 528 if (imgp->opened) { 529 VOP_CLOSE(binvp, FREAD, td->td_ucred, td); 530 imgp->opened = 0; 531 } 532 vput(binvp); 533 vm_object_deallocate(imgp->object); 534 imgp->object = NULL; 535 /* set new name to that of the interpreter */ 536 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 537 UIO_SYSSPACE, imgp->interpreter_name, td); 538 args->fname = imgp->interpreter_name; 539 goto interpret; 540 } 541 542 /* 543 * NB: We unlock the vnode here because it is believed that none 544 * of the sv_copyout_strings/sv_fixup operations require the vnode. 545 */ 546 VOP_UNLOCK(imgp->vp, 0); 547 548 /* 549 * Do the best to calculate the full path to the image file. 550 */ 551 if (imgp->auxargs != NULL && 552 ((args->fname != NULL && args->fname[0] == '/') || 553 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0)) 554 imgp->execpath = args->fname; 555 556 if (disallow_high_osrel && 557 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 558 error = ENOEXEC; 559 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 560 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 561 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 562 goto exec_fail_dealloc; 563 } 564 565 /* 566 * Copy out strings (args and env) and initialize stack base 567 */ 568 if (p->p_sysent->sv_copyout_strings) 569 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 570 else 571 stack_base = exec_copyout_strings(imgp); 572 573 /* 574 * If custom stack fixup routine present for this process 575 * let it do the stack setup. 576 * Else stuff argument count as first item on stack 577 */ 578 if (p->p_sysent->sv_fixup != NULL) 579 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 580 else 581 suword(--stack_base, imgp->args->argc); 582 583 /* 584 * For security and other reasons, the file descriptor table cannot 585 * be shared after an exec. 586 */ 587 fdunshare(td); 588 /* close files on exec */ 589 fdcloseexec(td); 590 591 /* 592 * Malloc things before we need locks. 593 */ 594 i = imgp->args->begin_envv - imgp->args->begin_argv; 595 /* Cache arguments if they fit inside our allowance */ 596 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 597 newargs = pargs_alloc(i); 598 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 599 } 600 601 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 602 603 /* Get a reference to the vnode prior to locking the proc */ 604 VREF(binvp); 605 606 /* 607 * For security and other reasons, signal handlers cannot 608 * be shared after an exec. The new process gets a copy of the old 609 * handlers. In execsigs(), the new process will have its signals 610 * reset. 611 */ 612 if (sigacts_shared(p->p_sigacts)) { 613 oldsigacts = p->p_sigacts; 614 newsigacts = sigacts_alloc(); 615 sigacts_copy(newsigacts, oldsigacts); 616 } else { 617 oldsigacts = NULL; 618 newsigacts = NULL; /* satisfy gcc */ 619 } 620 621 PROC_LOCK(p); 622 if (oldsigacts) 623 p->p_sigacts = newsigacts; 624 oldcred = p->p_ucred; 625 /* Stop profiling */ 626 stopprofclock(p); 627 628 /* reset caught signals */ 629 execsigs(p); 630 631 /* name this process - nameiexec(p, ndp) */ 632 bzero(p->p_comm, sizeof(p->p_comm)); 633 if (args->fname) 634 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 635 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 636 else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0) 637 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 638 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 639 #ifdef KTR 640 sched_clear_tdname(td); 641 #endif 642 643 /* 644 * mark as execed, wakeup the process that vforked (if any) and tell 645 * it that it now has its own resources back 646 */ 647 p->p_flag |= P_EXEC; 648 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0) 649 p->p_flag2 &= ~P2_NOTRACE; 650 if (p->p_flag & P_PPWAIT) { 651 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 652 cv_broadcast(&p->p_pwait); 653 } 654 655 /* 656 * Implement image setuid/setgid. 657 * 658 * Don't honor setuid/setgid if the filesystem prohibits it or if 659 * the process is being traced. 660 * 661 * We disable setuid/setgid/etc in compatibility mode on the basis 662 * that most setugid applications are not written with that 663 * environment in mind, and will therefore almost certainly operate 664 * incorrectly. In principle there's no reason that setugid 665 * applications might not be useful in capability mode, so we may want 666 * to reconsider this conservative design choice in the future. 667 * 668 * XXXMAC: For the time being, use NOSUID to also prohibit 669 * transitions on the file system. 670 */ 671 credential_changing = 0; 672 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 673 attr.va_uid; 674 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 675 attr.va_gid; 676 #ifdef MAC 677 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 678 interpvplabel, imgp); 679 credential_changing |= will_transition; 680 #endif 681 682 if (credential_changing && 683 #ifdef CAPABILITY_MODE 684 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 685 #endif 686 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 687 (p->p_flag & P_TRACED) == 0) { 688 /* 689 * Turn off syscall tracing for set-id programs, except for 690 * root. Record any set-id flags first to make sure that 691 * we do not regain any tracing during a possible block. 692 */ 693 setsugid(p); 694 695 #ifdef KTRACE 696 if (p->p_tracecred != NULL && 697 priv_check_cred(p->p_tracecred, 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 * Both fdsetugidsafety() and fdcheckstd() may call functions 705 * taking sleepable locks, so temporarily drop our locks. 706 */ 707 PROC_UNLOCK(p); 708 VOP_UNLOCK(imgp->vp, 0); 709 fdsetugidsafety(td); 710 error = fdcheckstd(td); 711 if (error != 0) 712 goto done1; 713 newcred = crdup(oldcred); 714 euip = uifind(attr.va_uid); 715 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 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 proc_set_cred(p, newcred); 740 } else { 741 if (oldcred->cr_uid == oldcred->cr_ruid && 742 oldcred->cr_gid == oldcred->cr_rgid) 743 p->p_flag &= ~P_SUGID; 744 /* 745 * Implement correct POSIX saved-id behavior. 746 * 747 * XXX: It's not clear that the existing behavior is 748 * POSIX-compliant. A number of sources indicate that the 749 * saved uid/gid should only be updated if the new ruid is 750 * not equal to the old ruid, or the new euid is not equal 751 * to the old euid and the new euid is not equal to the old 752 * ruid. The FreeBSD code always updates the saved uid/gid. 753 * Also, this code uses the new (replaced) euid and egid as 754 * the source, which may or may not be the right ones to use. 755 */ 756 if (oldcred->cr_svuid != oldcred->cr_uid || 757 oldcred->cr_svgid != oldcred->cr_gid) { 758 PROC_UNLOCK(p); 759 VOP_UNLOCK(imgp->vp, 0); 760 newcred = crdup(oldcred); 761 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 762 PROC_LOCK(p); 763 change_svuid(newcred, newcred->cr_uid); 764 change_svgid(newcred, newcred->cr_gid); 765 proc_set_cred(p, newcred); 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 VOP_UNLOCK(imgp->vp, 0); 839 done1: 840 /* 841 * Free any resources malloc'd earlier that we didn't use. 842 */ 843 if (euip != NULL) 844 uifree(euip); 845 if (newcred != NULL) 846 crfree(oldcred); 847 848 /* 849 * Handle deferred decrement of ref counts. 850 */ 851 if (textvp != NULL) 852 vrele(textvp); 853 if (error != 0) 854 vrele(binvp); 855 #ifdef KTRACE 856 if (tracevp != NULL) 857 vrele(tracevp); 858 if (tracecred != NULL) 859 crfree(tracecred); 860 #endif 861 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 862 pargs_drop(oldargs); 863 pargs_drop(newargs); 864 if (oldsigacts != NULL) 865 sigacts_free(oldsigacts); 866 867 exec_fail_dealloc: 868 869 /* 870 * free various allocated resources 871 */ 872 if (imgp->firstpage != NULL) 873 exec_unmap_first_page(imgp); 874 875 if (imgp->vp != NULL) { 876 if (args->fname) 877 NDFREE(&nd, NDF_ONLY_PNBUF); 878 if (imgp->opened) 879 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 880 vput(imgp->vp); 881 } 882 883 if (imgp->object != NULL) 884 vm_object_deallocate(imgp->object); 885 886 free(imgp->freepath, M_TEMP); 887 888 if (error == 0) { 889 PROC_LOCK(p); 890 td->td_dbgflags |= TDB_EXEC; 891 PROC_UNLOCK(p); 892 893 /* 894 * Stop the process here if its stop event mask has 895 * the S_EXEC bit set. 896 */ 897 STOPEVENT(p, S_EXEC, 0); 898 goto done2; 899 } 900 901 exec_fail: 902 /* we're done here, clear P_INEXEC */ 903 PROC_LOCK(p); 904 p->p_flag &= ~P_INEXEC; 905 PROC_UNLOCK(p); 906 907 SDT_PROBE(proc, kernel, , exec__failure, error, 0, 0, 0, 0); 908 909 done2: 910 #ifdef MAC 911 mac_execve_exit(imgp); 912 mac_execve_interpreter_exit(interpvplabel); 913 #endif 914 exec_free_args(args); 915 916 if (error && imgp->vmspace_destroyed) { 917 /* sorry, no more process anymore. exit gracefully */ 918 exit1(td, W_EXITCODE(0, SIGABRT)); 919 /* NOT REACHED */ 920 } 921 922 #ifdef KTRACE 923 if (error == 0) 924 ktrprocctor(p); 925 #endif 926 927 return (error); 928 } 929 930 int 931 exec_map_first_page(imgp) 932 struct image_params *imgp; 933 { 934 int rv, i; 935 int initial_pagein; 936 vm_page_t ma[VM_INITIAL_PAGEIN]; 937 vm_object_t object; 938 939 if (imgp->firstpage != NULL) 940 exec_unmap_first_page(imgp); 941 942 object = imgp->vp->v_object; 943 if (object == NULL) 944 return (EACCES); 945 VM_OBJECT_WLOCK(object); 946 #if VM_NRESERVLEVEL > 0 947 vm_object_color(object, 0); 948 #endif 949 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL); 950 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 951 initial_pagein = VM_INITIAL_PAGEIN; 952 if (initial_pagein > object->size) 953 initial_pagein = object->size; 954 for (i = 1; i < initial_pagein; i++) { 955 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 956 if (ma[i]->valid) 957 break; 958 if (vm_page_tryxbusy(ma[i])) 959 break; 960 } else { 961 ma[i] = vm_page_alloc(object, i, 962 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 963 if (ma[i] == NULL) 964 break; 965 } 966 } 967 initial_pagein = i; 968 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 969 if (rv != VM_PAGER_OK) { 970 vm_page_lock(ma[0]); 971 vm_page_free(ma[0]); 972 vm_page_unlock(ma[0]); 973 VM_OBJECT_WUNLOCK(object); 974 return (EIO); 975 } 976 } 977 vm_page_xunbusy(ma[0]); 978 vm_page_lock(ma[0]); 979 vm_page_hold(ma[0]); 980 vm_page_activate(ma[0]); 981 vm_page_unlock(ma[0]); 982 VM_OBJECT_WUNLOCK(object); 983 984 imgp->firstpage = sf_buf_alloc(ma[0], 0); 985 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 986 987 return (0); 988 } 989 990 void 991 exec_unmap_first_page(imgp) 992 struct image_params *imgp; 993 { 994 vm_page_t m; 995 996 if (imgp->firstpage != NULL) { 997 m = sf_buf_page(imgp->firstpage); 998 sf_buf_free(imgp->firstpage); 999 imgp->firstpage = NULL; 1000 vm_page_lock(m); 1001 vm_page_unhold(m); 1002 vm_page_unlock(m); 1003 } 1004 } 1005 1006 /* 1007 * Destroy old address space, and allocate a new stack 1008 * The new stack is only SGROWSIZ large because it is grown 1009 * automatically in trap.c. 1010 */ 1011 int 1012 exec_new_vmspace(imgp, sv) 1013 struct image_params *imgp; 1014 struct sysentvec *sv; 1015 { 1016 int error; 1017 struct proc *p = imgp->proc; 1018 struct vmspace *vmspace = p->p_vmspace; 1019 vm_object_t obj; 1020 struct rlimit rlim_stack; 1021 vm_offset_t sv_minuser, stack_addr; 1022 vm_map_t map; 1023 u_long ssiz; 1024 1025 imgp->vmspace_destroyed = 1; 1026 imgp->sysent = sv; 1027 1028 /* May be called with Giant held */ 1029 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1030 1031 /* 1032 * Blow away entire process VM, if address space not shared, 1033 * otherwise, create a new VM space so that other threads are 1034 * not disrupted 1035 */ 1036 map = &vmspace->vm_map; 1037 if (map_at_zero) 1038 sv_minuser = sv->sv_minuser; 1039 else 1040 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1041 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1042 vm_map_max(map) == sv->sv_maxuser) { 1043 shmexit(vmspace); 1044 pmap_remove_pages(vmspace_pmap(vmspace)); 1045 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1046 } else { 1047 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1048 if (error) 1049 return (error); 1050 vmspace = p->p_vmspace; 1051 map = &vmspace->vm_map; 1052 } 1053 1054 /* Map a shared page */ 1055 obj = sv->sv_shared_page_obj; 1056 if (obj != NULL) { 1057 vm_object_reference(obj); 1058 error = vm_map_fixed(map, obj, 0, 1059 sv->sv_shared_page_base, sv->sv_shared_page_len, 1060 VM_PROT_READ | VM_PROT_EXECUTE, 1061 VM_PROT_READ | VM_PROT_EXECUTE, 1062 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1063 if (error) { 1064 vm_object_deallocate(obj); 1065 return (error); 1066 } 1067 } 1068 1069 /* Allocate a new stack */ 1070 if (imgp->stack_sz != 0) { 1071 ssiz = trunc_page(imgp->stack_sz); 1072 PROC_LOCK(p); 1073 lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack); 1074 PROC_UNLOCK(p); 1075 if (ssiz > rlim_stack.rlim_max) 1076 ssiz = rlim_stack.rlim_max; 1077 if (ssiz > rlim_stack.rlim_cur) { 1078 rlim_stack.rlim_cur = ssiz; 1079 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack); 1080 } 1081 } else if (sv->sv_maxssiz != NULL) { 1082 ssiz = *sv->sv_maxssiz; 1083 } else { 1084 ssiz = maxssiz; 1085 } 1086 stack_addr = sv->sv_usrstack - ssiz; 1087 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1088 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1089 sv->sv_stackprot, 1090 VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1091 if (error) 1092 return (error); 1093 1094 /* 1095 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they 1096 * are still used to enforce the stack rlimit on the process stack. 1097 */ 1098 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1099 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1100 1101 return (0); 1102 } 1103 1104 /* 1105 * Copy out argument and environment strings from the old process address 1106 * space into the temporary string buffer. 1107 */ 1108 int 1109 exec_copyin_args(struct image_args *args, char *fname, 1110 enum uio_seg segflg, char **argv, char **envv) 1111 { 1112 u_long argp, envp; 1113 int error; 1114 size_t length; 1115 1116 bzero(args, sizeof(*args)); 1117 if (argv == NULL) 1118 return (EFAULT); 1119 1120 /* 1121 * Allocate demand-paged memory for the file name, argument, and 1122 * environment strings. 1123 */ 1124 error = exec_alloc_args(args); 1125 if (error != 0) 1126 return (error); 1127 1128 /* 1129 * Copy the file name. 1130 */ 1131 if (fname != NULL) { 1132 args->fname = args->buf; 1133 error = (segflg == UIO_SYSSPACE) ? 1134 copystr(fname, args->fname, PATH_MAX, &length) : 1135 copyinstr(fname, args->fname, PATH_MAX, &length); 1136 if (error != 0) 1137 goto err_exit; 1138 } else 1139 length = 0; 1140 1141 args->begin_argv = args->buf + length; 1142 args->endp = args->begin_argv; 1143 args->stringspace = ARG_MAX; 1144 1145 /* 1146 * extract arguments first 1147 */ 1148 for (;;) { 1149 error = fueword(argv++, &argp); 1150 if (error == -1) { 1151 error = EFAULT; 1152 goto err_exit; 1153 } 1154 if (argp == 0) 1155 break; 1156 error = copyinstr((void *)(uintptr_t)argp, args->endp, 1157 args->stringspace, &length); 1158 if (error != 0) { 1159 if (error == ENAMETOOLONG) 1160 error = E2BIG; 1161 goto err_exit; 1162 } 1163 args->stringspace -= length; 1164 args->endp += length; 1165 args->argc++; 1166 } 1167 1168 args->begin_envv = args->endp; 1169 1170 /* 1171 * extract environment strings 1172 */ 1173 if (envv) { 1174 for (;;) { 1175 error = fueword(envv++, &envp); 1176 if (error == -1) { 1177 error = EFAULT; 1178 goto err_exit; 1179 } 1180 if (envp == 0) 1181 break; 1182 error = copyinstr((void *)(uintptr_t)envp, 1183 args->endp, args->stringspace, &length); 1184 if (error != 0) { 1185 if (error == ENAMETOOLONG) 1186 error = E2BIG; 1187 goto err_exit; 1188 } 1189 args->stringspace -= length; 1190 args->endp += length; 1191 args->envc++; 1192 } 1193 } 1194 1195 return (0); 1196 1197 err_exit: 1198 exec_free_args(args); 1199 return (error); 1200 } 1201 1202 /* 1203 * Allocate temporary demand-paged, zero-filled memory for the file name, 1204 * argument, and environment strings. Returns zero if the allocation succeeds 1205 * and ENOMEM otherwise. 1206 */ 1207 int 1208 exec_alloc_args(struct image_args *args) 1209 { 1210 1211 args->buf = (char *)kmap_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 1212 return (args->buf != NULL ? 0 : ENOMEM); 1213 } 1214 1215 void 1216 exec_free_args(struct image_args *args) 1217 { 1218 1219 if (args->buf != NULL) { 1220 kmap_free_wakeup(exec_map, (vm_offset_t)args->buf, 1221 PATH_MAX + ARG_MAX); 1222 args->buf = NULL; 1223 } 1224 if (args->fname_buf != NULL) { 1225 free(args->fname_buf, M_TEMP); 1226 args->fname_buf = NULL; 1227 } 1228 } 1229 1230 /* 1231 * Copy strings out to the new process address space, constructing new arg 1232 * and env vector tables. Return a pointer to the base so that it can be used 1233 * as the initial stack pointer. 1234 */ 1235 register_t * 1236 exec_copyout_strings(imgp) 1237 struct image_params *imgp; 1238 { 1239 int argc, envc; 1240 char **vectp; 1241 char *stringp; 1242 uintptr_t destp; 1243 register_t *stack_base; 1244 struct ps_strings *arginfo; 1245 struct proc *p; 1246 size_t execpath_len; 1247 int szsigcode, szps; 1248 char canary[sizeof(long) * 8]; 1249 1250 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1251 /* 1252 * Calculate string base and vector table pointers. 1253 * Also deal with signal trampoline code for this exec type. 1254 */ 1255 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1256 execpath_len = strlen(imgp->execpath) + 1; 1257 else 1258 execpath_len = 0; 1259 p = imgp->proc; 1260 szsigcode = 0; 1261 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1262 if (p->p_sysent->sv_sigcode_base == 0) { 1263 if (p->p_sysent->sv_szsigcode != NULL) 1264 szsigcode = *(p->p_sysent->sv_szsigcode); 1265 } 1266 destp = (uintptr_t)arginfo; 1267 1268 /* 1269 * install sigcode 1270 */ 1271 if (szsigcode != 0) { 1272 destp -= szsigcode; 1273 destp = rounddown2(destp, sizeof(void *)); 1274 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode); 1275 } 1276 1277 /* 1278 * Copy the image path for the rtld. 1279 */ 1280 if (execpath_len != 0) { 1281 destp -= execpath_len; 1282 imgp->execpathp = destp; 1283 copyout(imgp->execpath, (void *)destp, execpath_len); 1284 } 1285 1286 /* 1287 * Prepare the canary for SSP. 1288 */ 1289 arc4rand(canary, sizeof(canary), 0); 1290 destp -= sizeof(canary); 1291 imgp->canary = destp; 1292 copyout(canary, (void *)destp, sizeof(canary)); 1293 imgp->canarylen = sizeof(canary); 1294 1295 /* 1296 * Prepare the pagesizes array. 1297 */ 1298 destp -= szps; 1299 destp = rounddown2(destp, sizeof(void *)); 1300 imgp->pagesizes = destp; 1301 copyout(pagesizes, (void *)destp, szps); 1302 imgp->pagesizeslen = szps; 1303 1304 destp -= ARG_MAX - imgp->args->stringspace; 1305 destp = rounddown2(destp, sizeof(void *)); 1306 1307 /* 1308 * If we have a valid auxargs ptr, prepare some room 1309 * on the stack. 1310 */ 1311 if (imgp->auxargs) { 1312 /* 1313 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1314 * lower compatibility. 1315 */ 1316 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1317 (AT_COUNT * 2); 1318 /* 1319 * The '+ 2' is for the null pointers at the end of each of 1320 * the arg and env vector sets,and imgp->auxarg_size is room 1321 * for argument of Runtime loader. 1322 */ 1323 vectp = (char **)(destp - (imgp->args->argc + 1324 imgp->args->envc + 2 + imgp->auxarg_size) 1325 * sizeof(char *)); 1326 } else { 1327 /* 1328 * The '+ 2' is for the null pointers at the end of each of 1329 * the arg and env vector sets 1330 */ 1331 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc 1332 + 2) * sizeof(char *)); 1333 } 1334 1335 /* 1336 * vectp also becomes our initial stack base 1337 */ 1338 stack_base = (register_t *)vectp; 1339 1340 stringp = imgp->args->begin_argv; 1341 argc = imgp->args->argc; 1342 envc = imgp->args->envc; 1343 1344 /* 1345 * Copy out strings - arguments and environment. 1346 */ 1347 copyout(stringp, (void *)destp, ARG_MAX - imgp->args->stringspace); 1348 1349 /* 1350 * Fill in "ps_strings" struct for ps, w, etc. 1351 */ 1352 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1353 suword32(&arginfo->ps_nargvstr, argc); 1354 1355 /* 1356 * Fill in argument portion of vector table. 1357 */ 1358 for (; argc > 0; --argc) { 1359 suword(vectp++, (long)(intptr_t)destp); 1360 while (*stringp++ != 0) 1361 destp++; 1362 destp++; 1363 } 1364 1365 /* a null vector table pointer separates the argp's from the envp's */ 1366 suword(vectp++, 0); 1367 1368 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1369 suword32(&arginfo->ps_nenvstr, envc); 1370 1371 /* 1372 * Fill in environment portion of vector table. 1373 */ 1374 for (; envc > 0; --envc) { 1375 suword(vectp++, (long)(intptr_t)destp); 1376 while (*stringp++ != 0) 1377 destp++; 1378 destp++; 1379 } 1380 1381 /* end of vector table is a null pointer */ 1382 suword(vectp, 0); 1383 1384 return (stack_base); 1385 } 1386 1387 /* 1388 * Check permissions of file to execute. 1389 * Called with imgp->vp locked. 1390 * Return 0 for success or error code on failure. 1391 */ 1392 int 1393 exec_check_permissions(imgp) 1394 struct image_params *imgp; 1395 { 1396 struct vnode *vp = imgp->vp; 1397 struct vattr *attr = imgp->attr; 1398 struct thread *td; 1399 int error, writecount; 1400 1401 td = curthread; 1402 1403 /* Get file attributes */ 1404 error = VOP_GETATTR(vp, attr, td->td_ucred); 1405 if (error) 1406 return (error); 1407 1408 #ifdef MAC 1409 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1410 if (error) 1411 return (error); 1412 #endif 1413 1414 /* 1415 * 1) Check if file execution is disabled for the filesystem that 1416 * this file resides on. 1417 * 2) Ensure that at least one execute bit is on. Otherwise, a 1418 * privileged user will always succeed, and we don't want this 1419 * to happen unless the file really is executable. 1420 * 3) Ensure that the file is a regular file. 1421 */ 1422 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1423 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1424 (attr->va_type != VREG)) 1425 return (EACCES); 1426 1427 /* 1428 * Zero length files can't be exec'd 1429 */ 1430 if (attr->va_size == 0) 1431 return (ENOEXEC); 1432 1433 /* 1434 * Check for execute permission to file based on current credentials. 1435 */ 1436 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1437 if (error) 1438 return (error); 1439 1440 /* 1441 * Check number of open-for-writes on the file and deny execution 1442 * if there are any. 1443 */ 1444 error = VOP_GET_WRITECOUNT(vp, &writecount); 1445 if (error != 0) 1446 return (error); 1447 if (writecount != 0) 1448 return (ETXTBSY); 1449 1450 /* 1451 * Call filesystem specific open routine (which does nothing in the 1452 * general case). 1453 */ 1454 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1455 if (error == 0) 1456 imgp->opened = 1; 1457 return (error); 1458 } 1459 1460 /* 1461 * Exec handler registration 1462 */ 1463 int 1464 exec_register(execsw_arg) 1465 const struct execsw *execsw_arg; 1466 { 1467 const struct execsw **es, **xs, **newexecsw; 1468 int count = 2; /* New slot and trailing NULL */ 1469 1470 if (execsw) 1471 for (es = execsw; *es; es++) 1472 count++; 1473 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1474 if (newexecsw == NULL) 1475 return (ENOMEM); 1476 xs = newexecsw; 1477 if (execsw) 1478 for (es = execsw; *es; es++) 1479 *xs++ = *es; 1480 *xs++ = execsw_arg; 1481 *xs = NULL; 1482 if (execsw) 1483 free(execsw, M_TEMP); 1484 execsw = newexecsw; 1485 return (0); 1486 } 1487 1488 int 1489 exec_unregister(execsw_arg) 1490 const struct execsw *execsw_arg; 1491 { 1492 const struct execsw **es, **xs, **newexecsw; 1493 int count = 1; 1494 1495 if (execsw == NULL) 1496 panic("unregister with no handlers left?\n"); 1497 1498 for (es = execsw; *es; es++) { 1499 if (*es == execsw_arg) 1500 break; 1501 } 1502 if (*es == NULL) 1503 return (ENOENT); 1504 for (es = execsw; *es; es++) 1505 if (*es != execsw_arg) 1506 count++; 1507 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1508 if (newexecsw == NULL) 1509 return (ENOMEM); 1510 xs = newexecsw; 1511 for (es = execsw; *es; es++) 1512 if (*es != execsw_arg) 1513 *xs++ = *es; 1514 *xs = NULL; 1515 if (execsw) 1516 free(execsw, M_TEMP); 1517 execsw = newexecsw; 1518 return (0); 1519 } 1520