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 *oldtextvp = NULL, *newtextvp; 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 newtextvp = nd.ni_vp; 437 imgp->vp = newtextvp; 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), &newtextvp); 445 if (error) 446 goto exec_fail; 447 vn_lock(newtextvp, LK_EXCLUSIVE | LK_RETRY); 448 AUDIT_ARG_VNODE1(newtextvp); 449 imgp->vp = newtextvp; 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(newtextvp, &interpvplabel); 527 #endif 528 if (imgp->opened) { 529 VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td); 530 imgp->opened = 0; 531 } 532 vput(newtextvp); 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 /* ABI enforces the use of Capsicum. Switch into capabilities mode. */ 566 if (SV_PROC_FLAG(p, SV_CAPSICUM)) 567 sys_cap_enter(td, NULL); 568 569 /* 570 * Copy out strings (args and env) and initialize stack base 571 */ 572 if (p->p_sysent->sv_copyout_strings) 573 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 574 else 575 stack_base = exec_copyout_strings(imgp); 576 577 /* 578 * If custom stack fixup routine present for this process 579 * let it do the stack setup. 580 * Else stuff argument count as first item on stack 581 */ 582 if (p->p_sysent->sv_fixup != NULL) 583 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 584 else 585 suword(--stack_base, imgp->args->argc); 586 587 if (args->fdp != NULL) { 588 /* Install a brand new file descriptor table. */ 589 fdinstall_remapped(td, args->fdp); 590 args->fdp = NULL; 591 } else { 592 /* 593 * Keep on using the existing file descriptor table. For 594 * security and other reasons, the file descriptor table 595 * cannot be shared after an exec. 596 */ 597 fdunshare(td); 598 /* close files on exec */ 599 fdcloseexec(td); 600 } 601 602 /* 603 * Malloc things before we need locks. 604 */ 605 i = imgp->args->begin_envv - imgp->args->begin_argv; 606 /* Cache arguments if they fit inside our allowance */ 607 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 608 newargs = pargs_alloc(i); 609 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 610 } 611 612 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 613 614 /* 615 * For security and other reasons, signal handlers cannot 616 * be shared after an exec. The new process gets a copy of the old 617 * handlers. In execsigs(), the new process will have its signals 618 * reset. 619 */ 620 if (sigacts_shared(p->p_sigacts)) { 621 oldsigacts = p->p_sigacts; 622 newsigacts = sigacts_alloc(); 623 sigacts_copy(newsigacts, oldsigacts); 624 } else { 625 oldsigacts = NULL; 626 newsigacts = NULL; /* satisfy gcc */ 627 } 628 629 PROC_LOCK(p); 630 if (oldsigacts) 631 p->p_sigacts = newsigacts; 632 oldcred = p->p_ucred; 633 /* Stop profiling */ 634 stopprofclock(p); 635 636 /* reset caught signals */ 637 execsigs(p); 638 639 /* name this process - nameiexec(p, ndp) */ 640 bzero(p->p_comm, sizeof(p->p_comm)); 641 if (args->fname) 642 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 643 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 644 else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0) 645 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 646 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 647 #ifdef KTR 648 sched_clear_tdname(td); 649 #endif 650 651 /* 652 * mark as execed, wakeup the process that vforked (if any) and tell 653 * it that it now has its own resources back 654 */ 655 p->p_flag |= P_EXEC; 656 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0) 657 p->p_flag2 &= ~P2_NOTRACE; 658 if (p->p_flag & P_PPWAIT) { 659 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 660 cv_broadcast(&p->p_pwait); 661 } 662 663 /* 664 * Implement image setuid/setgid. 665 * 666 * Don't honor setuid/setgid if the filesystem prohibits it or if 667 * the process is being traced. 668 * 669 * We disable setuid/setgid/etc in compatibility mode on the basis 670 * that most setugid applications are not written with that 671 * environment in mind, and will therefore almost certainly operate 672 * incorrectly. In principle there's no reason that setugid 673 * applications might not be useful in capability mode, so we may want 674 * to reconsider this conservative design choice in the future. 675 * 676 * XXXMAC: For the time being, use NOSUID to also prohibit 677 * transitions on the file system. 678 */ 679 credential_changing = 0; 680 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 681 attr.va_uid; 682 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 683 attr.va_gid; 684 #ifdef MAC 685 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 686 interpvplabel, imgp); 687 credential_changing |= will_transition; 688 #endif 689 690 if (credential_changing && 691 #ifdef CAPABILITY_MODE 692 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 693 #endif 694 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 695 (p->p_flag & P_TRACED) == 0) { 696 /* 697 * Turn off syscall tracing for set-id programs, except for 698 * root. Record any set-id flags first to make sure that 699 * we do not regain any tracing during a possible block. 700 */ 701 setsugid(p); 702 703 #ifdef KTRACE 704 if (p->p_tracecred != NULL && 705 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0)) 706 ktrprocexec(p, &tracecred, &tracevp); 707 #endif 708 /* 709 * Close any file descriptors 0..2 that reference procfs, 710 * then make sure file descriptors 0..2 are in use. 711 * 712 * Both fdsetugidsafety() and fdcheckstd() may call functions 713 * taking sleepable locks, so temporarily drop our locks. 714 */ 715 PROC_UNLOCK(p); 716 VOP_UNLOCK(imgp->vp, 0); 717 fdsetugidsafety(td); 718 error = fdcheckstd(td); 719 if (error != 0) 720 goto done1; 721 newcred = crdup(oldcred); 722 euip = uifind(attr.va_uid); 723 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 724 PROC_LOCK(p); 725 /* 726 * Set the new credentials. 727 */ 728 if (attr.va_mode & S_ISUID) 729 change_euid(newcred, euip); 730 if (attr.va_mode & S_ISGID) 731 change_egid(newcred, attr.va_gid); 732 #ifdef MAC 733 if (will_transition) { 734 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 735 interpvplabel, imgp); 736 } 737 #endif 738 /* 739 * Implement correct POSIX saved-id behavior. 740 * 741 * XXXMAC: Note that the current logic will save the 742 * uid and gid if a MAC domain transition occurs, even 743 * though maybe it shouldn't. 744 */ 745 change_svuid(newcred, newcred->cr_uid); 746 change_svgid(newcred, newcred->cr_gid); 747 proc_set_cred(p, newcred); 748 } else { 749 if (oldcred->cr_uid == oldcred->cr_ruid && 750 oldcred->cr_gid == oldcred->cr_rgid) 751 p->p_flag &= ~P_SUGID; 752 /* 753 * Implement correct POSIX saved-id behavior. 754 * 755 * XXX: It's not clear that the existing behavior is 756 * POSIX-compliant. A number of sources indicate that the 757 * saved uid/gid should only be updated if the new ruid is 758 * not equal to the old ruid, or the new euid is not equal 759 * to the old euid and the new euid is not equal to the old 760 * ruid. The FreeBSD code always updates the saved uid/gid. 761 * Also, this code uses the new (replaced) euid and egid as 762 * the source, which may or may not be the right ones to use. 763 */ 764 if (oldcred->cr_svuid != oldcred->cr_uid || 765 oldcred->cr_svgid != oldcred->cr_gid) { 766 PROC_UNLOCK(p); 767 VOP_UNLOCK(imgp->vp, 0); 768 newcred = crdup(oldcred); 769 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 770 PROC_LOCK(p); 771 change_svuid(newcred, newcred->cr_uid); 772 change_svgid(newcred, newcred->cr_gid); 773 proc_set_cred(p, newcred); 774 } 775 } 776 777 /* 778 * Store the vp for use in procfs. This vnode was referenced by namei 779 * or fgetvp_exec. 780 */ 781 oldtextvp = p->p_textvp; 782 p->p_textvp = newtextvp; 783 784 #ifdef KDTRACE_HOOKS 785 /* 786 * Tell the DTrace fasttrap provider about the exec if it 787 * has declared an interest. 788 */ 789 if (dtrace_fasttrap_exec) 790 dtrace_fasttrap_exec(p); 791 #endif 792 793 /* 794 * Notify others that we exec'd, and clear the P_INEXEC flag 795 * as we're now a bona fide freshly-execed process. 796 */ 797 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 798 p->p_flag &= ~P_INEXEC; 799 800 /* clear "fork but no exec" flag, as we _are_ execing */ 801 p->p_acflag &= ~AFORK; 802 803 /* 804 * Free any previous argument cache and replace it with 805 * the new argument cache, if any. 806 */ 807 oldargs = p->p_args; 808 p->p_args = newargs; 809 newargs = NULL; 810 811 #ifdef HWPMC_HOOKS 812 /* 813 * Check if system-wide sampling is in effect or if the 814 * current process is using PMCs. If so, do exec() time 815 * processing. This processing needs to happen AFTER the 816 * P_INEXEC flag is cleared. 817 * 818 * The proc lock needs to be released before taking the PMC 819 * SX. 820 */ 821 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 822 PROC_UNLOCK(p); 823 VOP_UNLOCK(imgp->vp, 0); 824 pe.pm_credentialschanged = credential_changing; 825 pe.pm_entryaddr = imgp->entry_addr; 826 827 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 828 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 829 } else 830 PROC_UNLOCK(p); 831 #else /* !HWPMC_HOOKS */ 832 PROC_UNLOCK(p); 833 #endif 834 835 /* Set values passed into the program in registers. */ 836 if (p->p_sysent->sv_setregs) 837 (*p->p_sysent->sv_setregs)(td, imgp, 838 (u_long)(uintptr_t)stack_base); 839 else 840 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 841 842 vfs_mark_atime(imgp->vp, td->td_ucred); 843 844 SDT_PROBE(proc, kernel, , exec__success, args->fname, 0, 0, 0, 0); 845 846 VOP_UNLOCK(imgp->vp, 0); 847 done1: 848 /* 849 * Free any resources malloc'd earlier that we didn't use. 850 */ 851 if (euip != NULL) 852 uifree(euip); 853 if (newcred != NULL) 854 crfree(oldcred); 855 856 /* 857 * Handle deferred decrement of ref counts. 858 */ 859 if (oldtextvp != NULL) 860 vrele(oldtextvp); 861 #ifdef KTRACE 862 if (tracevp != NULL) 863 vrele(tracevp); 864 if (tracecred != NULL) 865 crfree(tracecred); 866 #endif 867 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 868 pargs_drop(oldargs); 869 pargs_drop(newargs); 870 if (oldsigacts != NULL) 871 sigacts_free(oldsigacts); 872 873 exec_fail_dealloc: 874 875 /* 876 * free various allocated resources 877 */ 878 if (imgp->firstpage != NULL) 879 exec_unmap_first_page(imgp); 880 881 if (imgp->vp != NULL) { 882 if (args->fname) 883 NDFREE(&nd, NDF_ONLY_PNBUF); 884 if (imgp->opened) 885 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 886 if (error != 0) 887 vput(imgp->vp); 888 else 889 VOP_UNLOCK(imgp->vp, 0); 890 } 891 892 if (imgp->object != NULL) 893 vm_object_deallocate(imgp->object); 894 895 free(imgp->freepath, M_TEMP); 896 897 if (error == 0) { 898 PROC_LOCK(p); 899 td->td_dbgflags |= TDB_EXEC; 900 PROC_UNLOCK(p); 901 902 /* 903 * Stop the process here if its stop event mask has 904 * the S_EXEC bit set. 905 */ 906 STOPEVENT(p, S_EXEC, 0); 907 goto done2; 908 } 909 910 exec_fail: 911 /* we're done here, clear P_INEXEC */ 912 PROC_LOCK(p); 913 p->p_flag &= ~P_INEXEC; 914 PROC_UNLOCK(p); 915 916 SDT_PROBE(proc, kernel, , exec__failure, error, 0, 0, 0, 0); 917 918 done2: 919 #ifdef MAC 920 mac_execve_exit(imgp); 921 mac_execve_interpreter_exit(interpvplabel); 922 #endif 923 exec_free_args(args); 924 925 if (error && imgp->vmspace_destroyed) { 926 /* sorry, no more process anymore. exit gracefully */ 927 exit1(td, 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_WLOCK(object); 955 #if VM_NRESERVLEVEL > 0 956 vm_object_color(object, 0); 957 #endif 958 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL); 959 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 960 initial_pagein = VM_INITIAL_PAGEIN; 961 if (initial_pagein > object->size) 962 initial_pagein = object->size; 963 for (i = 1; i < initial_pagein; i++) { 964 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 965 if (ma[i]->valid) 966 break; 967 if (vm_page_tryxbusy(ma[i])) 968 break; 969 } else { 970 ma[i] = vm_page_alloc(object, i, 971 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 972 if (ma[i] == NULL) 973 break; 974 } 975 } 976 initial_pagein = i; 977 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 978 if (rv != VM_PAGER_OK) { 979 vm_page_lock(ma[0]); 980 vm_page_free(ma[0]); 981 vm_page_unlock(ma[0]); 982 VM_OBJECT_WUNLOCK(object); 983 return (EIO); 984 } 985 } 986 vm_page_xunbusy(ma[0]); 987 vm_page_lock(ma[0]); 988 vm_page_hold(ma[0]); 989 vm_page_activate(ma[0]); 990 vm_page_unlock(ma[0]); 991 VM_OBJECT_WUNLOCK(object); 992 993 imgp->firstpage = sf_buf_alloc(ma[0], 0); 994 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 995 996 return (0); 997 } 998 999 void 1000 exec_unmap_first_page(imgp) 1001 struct image_params *imgp; 1002 { 1003 vm_page_t m; 1004 1005 if (imgp->firstpage != NULL) { 1006 m = sf_buf_page(imgp->firstpage); 1007 sf_buf_free(imgp->firstpage); 1008 imgp->firstpage = NULL; 1009 vm_page_lock(m); 1010 vm_page_unhold(m); 1011 vm_page_unlock(m); 1012 } 1013 } 1014 1015 /* 1016 * Destroy old address space, and allocate a new stack 1017 * The new stack is only SGROWSIZ large because it is grown 1018 * automatically in trap.c. 1019 */ 1020 int 1021 exec_new_vmspace(imgp, sv) 1022 struct image_params *imgp; 1023 struct sysentvec *sv; 1024 { 1025 int error; 1026 struct proc *p = imgp->proc; 1027 struct vmspace *vmspace = p->p_vmspace; 1028 vm_object_t obj; 1029 struct rlimit rlim_stack; 1030 vm_offset_t sv_minuser, stack_addr; 1031 vm_map_t map; 1032 u_long ssiz; 1033 1034 imgp->vmspace_destroyed = 1; 1035 imgp->sysent = sv; 1036 1037 /* May be called with Giant held */ 1038 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1039 1040 /* 1041 * Blow away entire process VM, if address space not shared, 1042 * otherwise, create a new VM space so that other threads are 1043 * not disrupted 1044 */ 1045 map = &vmspace->vm_map; 1046 if (map_at_zero) 1047 sv_minuser = sv->sv_minuser; 1048 else 1049 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1050 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1051 vm_map_max(map) == sv->sv_maxuser) { 1052 shmexit(vmspace); 1053 pmap_remove_pages(vmspace_pmap(vmspace)); 1054 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1055 } else { 1056 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1057 if (error) 1058 return (error); 1059 vmspace = p->p_vmspace; 1060 map = &vmspace->vm_map; 1061 } 1062 1063 /* Map a shared page */ 1064 obj = sv->sv_shared_page_obj; 1065 if (obj != NULL) { 1066 vm_object_reference(obj); 1067 error = vm_map_fixed(map, obj, 0, 1068 sv->sv_shared_page_base, sv->sv_shared_page_len, 1069 VM_PROT_READ | VM_PROT_EXECUTE, 1070 VM_PROT_READ | VM_PROT_EXECUTE, 1071 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1072 if (error) { 1073 vm_object_deallocate(obj); 1074 return (error); 1075 } 1076 } 1077 1078 /* Allocate a new stack */ 1079 if (imgp->stack_sz != 0) { 1080 ssiz = trunc_page(imgp->stack_sz); 1081 PROC_LOCK(p); 1082 lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack); 1083 PROC_UNLOCK(p); 1084 if (ssiz > rlim_stack.rlim_max) 1085 ssiz = rlim_stack.rlim_max; 1086 if (ssiz > rlim_stack.rlim_cur) { 1087 rlim_stack.rlim_cur = ssiz; 1088 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack); 1089 } 1090 } else if (sv->sv_maxssiz != NULL) { 1091 ssiz = *sv->sv_maxssiz; 1092 } else { 1093 ssiz = maxssiz; 1094 } 1095 stack_addr = sv->sv_usrstack - ssiz; 1096 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1097 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1098 sv->sv_stackprot, 1099 VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1100 if (error) 1101 return (error); 1102 1103 /* 1104 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they 1105 * are still used to enforce the stack rlimit on the process stack. 1106 */ 1107 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1108 vmspace->vm_maxsaddr = (char *)stack_addr; 1109 1110 return (0); 1111 } 1112 1113 /* 1114 * Copy out argument and environment strings from the old process address 1115 * space into the temporary string buffer. 1116 */ 1117 int 1118 exec_copyin_args(struct image_args *args, char *fname, 1119 enum uio_seg segflg, char **argv, char **envv) 1120 { 1121 u_long argp, envp; 1122 int error; 1123 size_t length; 1124 1125 bzero(args, sizeof(*args)); 1126 if (argv == NULL) 1127 return (EFAULT); 1128 1129 /* 1130 * Allocate demand-paged memory for the file name, argument, and 1131 * environment strings. 1132 */ 1133 error = exec_alloc_args(args); 1134 if (error != 0) 1135 return (error); 1136 1137 /* 1138 * Copy the file name. 1139 */ 1140 if (fname != NULL) { 1141 args->fname = args->buf; 1142 error = (segflg == UIO_SYSSPACE) ? 1143 copystr(fname, args->fname, PATH_MAX, &length) : 1144 copyinstr(fname, args->fname, PATH_MAX, &length); 1145 if (error != 0) 1146 goto err_exit; 1147 } else 1148 length = 0; 1149 1150 args->begin_argv = args->buf + length; 1151 args->endp = args->begin_argv; 1152 args->stringspace = ARG_MAX; 1153 1154 /* 1155 * extract arguments first 1156 */ 1157 for (;;) { 1158 error = fueword(argv++, &argp); 1159 if (error == -1) { 1160 error = EFAULT; 1161 goto err_exit; 1162 } 1163 if (argp == 0) 1164 break; 1165 error = copyinstr((void *)(uintptr_t)argp, args->endp, 1166 args->stringspace, &length); 1167 if (error != 0) { 1168 if (error == ENAMETOOLONG) 1169 error = E2BIG; 1170 goto err_exit; 1171 } 1172 args->stringspace -= length; 1173 args->endp += length; 1174 args->argc++; 1175 } 1176 1177 args->begin_envv = args->endp; 1178 1179 /* 1180 * extract environment strings 1181 */ 1182 if (envv) { 1183 for (;;) { 1184 error = fueword(envv++, &envp); 1185 if (error == -1) { 1186 error = EFAULT; 1187 goto err_exit; 1188 } 1189 if (envp == 0) 1190 break; 1191 error = copyinstr((void *)(uintptr_t)envp, 1192 args->endp, args->stringspace, &length); 1193 if (error != 0) { 1194 if (error == ENAMETOOLONG) 1195 error = E2BIG; 1196 goto err_exit; 1197 } 1198 args->stringspace -= length; 1199 args->endp += length; 1200 args->envc++; 1201 } 1202 } 1203 1204 return (0); 1205 1206 err_exit: 1207 exec_free_args(args); 1208 return (error); 1209 } 1210 1211 int 1212 exec_copyin_data_fds(struct thread *td, struct image_args *args, 1213 const void *data, size_t datalen, const int *fds, size_t fdslen) 1214 { 1215 struct filedesc *ofdp; 1216 const char *p; 1217 int *kfds; 1218 int error; 1219 1220 memset(args, '\0', sizeof(*args)); 1221 ofdp = td->td_proc->p_fd; 1222 if (datalen >= ARG_MAX || fdslen > ofdp->fd_lastfile + 1) 1223 return (E2BIG); 1224 error = exec_alloc_args(args); 1225 if (error != 0) 1226 return (error); 1227 1228 args->begin_argv = args->buf; 1229 args->stringspace = ARG_MAX; 1230 1231 if (datalen > 0) { 1232 /* 1233 * Argument buffer has been provided. Copy it into the 1234 * kernel as a single string and add a terminating null 1235 * byte. 1236 */ 1237 error = copyin(data, args->begin_argv, datalen); 1238 if (error != 0) 1239 goto err_exit; 1240 args->begin_argv[datalen] = '\0'; 1241 args->endp = args->begin_argv + datalen + 1; 1242 args->stringspace -= datalen + 1; 1243 1244 /* 1245 * Traditional argument counting. Count the number of 1246 * null bytes. 1247 */ 1248 for (p = args->begin_argv; p < args->endp; ++p) 1249 if (*p == '\0') 1250 ++args->argc; 1251 } else { 1252 /* No argument buffer provided. */ 1253 args->endp = args->begin_argv; 1254 } 1255 /* There are no environment variables. */ 1256 args->begin_envv = args->endp; 1257 1258 /* Create new file descriptor table. */ 1259 kfds = malloc(fdslen * sizeof(int), M_TEMP, M_WAITOK); 1260 error = copyin(fds, kfds, fdslen * sizeof(int)); 1261 if (error != 0) { 1262 free(kfds, M_TEMP); 1263 goto err_exit; 1264 } 1265 error = fdcopy_remapped(ofdp, kfds, fdslen, &args->fdp); 1266 free(kfds, M_TEMP); 1267 if (error != 0) 1268 goto err_exit; 1269 1270 return (0); 1271 err_exit: 1272 exec_free_args(args); 1273 return (error); 1274 } 1275 1276 /* 1277 * Allocate temporary demand-paged, zero-filled memory for the file name, 1278 * argument, and environment strings. Returns zero if the allocation succeeds 1279 * and ENOMEM otherwise. 1280 */ 1281 int 1282 exec_alloc_args(struct image_args *args) 1283 { 1284 1285 args->buf = (char *)kmap_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 1286 return (args->buf != NULL ? 0 : ENOMEM); 1287 } 1288 1289 void 1290 exec_free_args(struct image_args *args) 1291 { 1292 1293 if (args->buf != NULL) { 1294 kmap_free_wakeup(exec_map, (vm_offset_t)args->buf, 1295 PATH_MAX + ARG_MAX); 1296 args->buf = NULL; 1297 } 1298 if (args->fname_buf != NULL) { 1299 free(args->fname_buf, M_TEMP); 1300 args->fname_buf = NULL; 1301 } 1302 if (args->fdp != NULL) 1303 fdescfree_remapped(args->fdp); 1304 } 1305 1306 /* 1307 * Copy strings out to the new process address space, constructing new arg 1308 * and env vector tables. Return a pointer to the base so that it can be used 1309 * as the initial stack pointer. 1310 */ 1311 register_t * 1312 exec_copyout_strings(imgp) 1313 struct image_params *imgp; 1314 { 1315 int argc, envc; 1316 char **vectp; 1317 char *stringp; 1318 uintptr_t destp; 1319 register_t *stack_base; 1320 struct ps_strings *arginfo; 1321 struct proc *p; 1322 size_t execpath_len; 1323 int szsigcode, szps; 1324 char canary[sizeof(long) * 8]; 1325 1326 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1327 /* 1328 * Calculate string base and vector table pointers. 1329 * Also deal with signal trampoline code for this exec type. 1330 */ 1331 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1332 execpath_len = strlen(imgp->execpath) + 1; 1333 else 1334 execpath_len = 0; 1335 p = imgp->proc; 1336 szsigcode = 0; 1337 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1338 if (p->p_sysent->sv_sigcode_base == 0) { 1339 if (p->p_sysent->sv_szsigcode != NULL) 1340 szsigcode = *(p->p_sysent->sv_szsigcode); 1341 } 1342 destp = (uintptr_t)arginfo; 1343 1344 /* 1345 * install sigcode 1346 */ 1347 if (szsigcode != 0) { 1348 destp -= szsigcode; 1349 destp = rounddown2(destp, sizeof(void *)); 1350 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode); 1351 } 1352 1353 /* 1354 * Copy the image path for the rtld. 1355 */ 1356 if (execpath_len != 0) { 1357 destp -= execpath_len; 1358 imgp->execpathp = destp; 1359 copyout(imgp->execpath, (void *)destp, execpath_len); 1360 } 1361 1362 /* 1363 * Prepare the canary for SSP. 1364 */ 1365 arc4rand(canary, sizeof(canary), 0); 1366 destp -= sizeof(canary); 1367 imgp->canary = destp; 1368 copyout(canary, (void *)destp, sizeof(canary)); 1369 imgp->canarylen = sizeof(canary); 1370 1371 /* 1372 * Prepare the pagesizes array. 1373 */ 1374 destp -= szps; 1375 destp = rounddown2(destp, sizeof(void *)); 1376 imgp->pagesizes = destp; 1377 copyout(pagesizes, (void *)destp, szps); 1378 imgp->pagesizeslen = szps; 1379 1380 destp -= ARG_MAX - imgp->args->stringspace; 1381 destp = rounddown2(destp, sizeof(void *)); 1382 1383 /* 1384 * If we have a valid auxargs ptr, prepare some room 1385 * on the stack. 1386 */ 1387 if (imgp->auxargs) { 1388 /* 1389 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1390 * lower compatibility. 1391 */ 1392 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1393 (AT_COUNT * 2); 1394 /* 1395 * The '+ 2' is for the null pointers at the end of each of 1396 * the arg and env vector sets,and imgp->auxarg_size is room 1397 * for argument of Runtime loader. 1398 */ 1399 vectp = (char **)(destp - (imgp->args->argc + 1400 imgp->args->envc + 2 + imgp->auxarg_size) 1401 * sizeof(char *)); 1402 } else { 1403 /* 1404 * The '+ 2' is for the null pointers at the end of each of 1405 * the arg and env vector sets 1406 */ 1407 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc 1408 + 2) * sizeof(char *)); 1409 } 1410 1411 /* 1412 * vectp also becomes our initial stack base 1413 */ 1414 stack_base = (register_t *)vectp; 1415 1416 stringp = imgp->args->begin_argv; 1417 argc = imgp->args->argc; 1418 envc = imgp->args->envc; 1419 1420 /* 1421 * Copy out strings - arguments and environment. 1422 */ 1423 copyout(stringp, (void *)destp, ARG_MAX - imgp->args->stringspace); 1424 1425 /* 1426 * Fill in "ps_strings" struct for ps, w, etc. 1427 */ 1428 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1429 suword32(&arginfo->ps_nargvstr, argc); 1430 1431 /* 1432 * Fill in argument portion of vector table. 1433 */ 1434 for (; argc > 0; --argc) { 1435 suword(vectp++, (long)(intptr_t)destp); 1436 while (*stringp++ != 0) 1437 destp++; 1438 destp++; 1439 } 1440 1441 /* a null vector table pointer separates the argp's from the envp's */ 1442 suword(vectp++, 0); 1443 1444 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1445 suword32(&arginfo->ps_nenvstr, envc); 1446 1447 /* 1448 * Fill in environment portion of vector table. 1449 */ 1450 for (; envc > 0; --envc) { 1451 suword(vectp++, (long)(intptr_t)destp); 1452 while (*stringp++ != 0) 1453 destp++; 1454 destp++; 1455 } 1456 1457 /* end of vector table is a null pointer */ 1458 suword(vectp, 0); 1459 1460 return (stack_base); 1461 } 1462 1463 /* 1464 * Check permissions of file to execute. 1465 * Called with imgp->vp locked. 1466 * Return 0 for success or error code on failure. 1467 */ 1468 int 1469 exec_check_permissions(imgp) 1470 struct image_params *imgp; 1471 { 1472 struct vnode *vp = imgp->vp; 1473 struct vattr *attr = imgp->attr; 1474 struct thread *td; 1475 int error, writecount; 1476 1477 td = curthread; 1478 1479 /* Get file attributes */ 1480 error = VOP_GETATTR(vp, attr, td->td_ucred); 1481 if (error) 1482 return (error); 1483 1484 #ifdef MAC 1485 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1486 if (error) 1487 return (error); 1488 #endif 1489 1490 /* 1491 * 1) Check if file execution is disabled for the filesystem that 1492 * this file resides on. 1493 * 2) Ensure that at least one execute bit is on. Otherwise, a 1494 * privileged user will always succeed, and we don't want this 1495 * to happen unless the file really is executable. 1496 * 3) Ensure that the file is a regular file. 1497 */ 1498 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1499 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1500 (attr->va_type != VREG)) 1501 return (EACCES); 1502 1503 /* 1504 * Zero length files can't be exec'd 1505 */ 1506 if (attr->va_size == 0) 1507 return (ENOEXEC); 1508 1509 /* 1510 * Check for execute permission to file based on current credentials. 1511 */ 1512 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1513 if (error) 1514 return (error); 1515 1516 /* 1517 * Check number of open-for-writes on the file and deny execution 1518 * if there are any. 1519 */ 1520 error = VOP_GET_WRITECOUNT(vp, &writecount); 1521 if (error != 0) 1522 return (error); 1523 if (writecount != 0) 1524 return (ETXTBSY); 1525 1526 /* 1527 * Call filesystem specific open routine (which does nothing in the 1528 * general case). 1529 */ 1530 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1531 if (error == 0) 1532 imgp->opened = 1; 1533 return (error); 1534 } 1535 1536 /* 1537 * Exec handler registration 1538 */ 1539 int 1540 exec_register(execsw_arg) 1541 const struct execsw *execsw_arg; 1542 { 1543 const struct execsw **es, **xs, **newexecsw; 1544 int count = 2; /* New slot and trailing NULL */ 1545 1546 if (execsw) 1547 for (es = execsw; *es; es++) 1548 count++; 1549 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1550 if (newexecsw == NULL) 1551 return (ENOMEM); 1552 xs = newexecsw; 1553 if (execsw) 1554 for (es = execsw; *es; es++) 1555 *xs++ = *es; 1556 *xs++ = execsw_arg; 1557 *xs = NULL; 1558 if (execsw) 1559 free(execsw, M_TEMP); 1560 execsw = newexecsw; 1561 return (0); 1562 } 1563 1564 int 1565 exec_unregister(execsw_arg) 1566 const struct execsw *execsw_arg; 1567 { 1568 const struct execsw **es, **xs, **newexecsw; 1569 int count = 1; 1570 1571 if (execsw == NULL) 1572 panic("unregister with no handlers left?\n"); 1573 1574 for (es = execsw; *es; es++) { 1575 if (*es == execsw_arg) 1576 break; 1577 } 1578 if (*es == NULL) 1579 return (ENOENT); 1580 for (es = execsw; *es; es++) 1581 if (*es != execsw_arg) 1582 count++; 1583 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1584 if (newexecsw == NULL) 1585 return (ENOMEM); 1586 xs = newexecsw; 1587 for (es = execsw; *es; es++) 1588 if (*es != execsw_arg) 1589 *xs++ = *es; 1590 *xs = NULL; 1591 if (execsw) 1592 free(execsw, M_TEMP); 1593 execsw = newexecsw; 1594 return (0); 1595 } 1596