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 int coredump_pack_fileinfo = 1; 104 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_fileinfo, CTLFLAG_RWTUN, 105 &coredump_pack_fileinfo, 0, 106 "Enable file path packing in 'procstat -f' coredump notes"); 107 108 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 109 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 110 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 111 static int do_execve(struct thread *td, struct image_args *args, 112 struct mac *mac_p); 113 114 /* XXX This should be vm_size_t. */ 115 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD, 116 NULL, 0, sysctl_kern_ps_strings, "LU", ""); 117 118 /* XXX This should be vm_size_t. */ 119 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 120 CTLFLAG_CAPRD, NULL, 0, sysctl_kern_usrstack, "LU", ""); 121 122 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 123 NULL, 0, sysctl_kern_stackprot, "I", ""); 124 125 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 126 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 127 &ps_arg_cache_limit, 0, ""); 128 129 static int disallow_high_osrel; 130 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW, 131 &disallow_high_osrel, 0, 132 "Disallow execution of binaries built for higher version of the world"); 133 134 static int map_at_zero = 0; 135 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RWTUN, &map_at_zero, 0, 136 "Permit processes to map an object at virtual address 0."); 137 138 static int 139 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 140 { 141 struct proc *p; 142 int error; 143 144 p = curproc; 145 #ifdef SCTL_MASK32 146 if (req->flags & SCTL_MASK32) { 147 unsigned int val; 148 val = (unsigned int)p->p_sysent->sv_psstrings; 149 error = SYSCTL_OUT(req, &val, sizeof(val)); 150 } else 151 #endif 152 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 153 sizeof(p->p_sysent->sv_psstrings)); 154 return error; 155 } 156 157 static int 158 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 159 { 160 struct proc *p; 161 int error; 162 163 p = curproc; 164 #ifdef SCTL_MASK32 165 if (req->flags & SCTL_MASK32) { 166 unsigned int val; 167 val = (unsigned int)p->p_sysent->sv_usrstack; 168 error = SYSCTL_OUT(req, &val, sizeof(val)); 169 } else 170 #endif 171 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 172 sizeof(p->p_sysent->sv_usrstack)); 173 return error; 174 } 175 176 static int 177 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 178 { 179 struct proc *p; 180 181 p = curproc; 182 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 183 sizeof(p->p_sysent->sv_stackprot))); 184 } 185 186 /* 187 * Each of the items is a pointer to a `const struct execsw', hence the 188 * double pointer here. 189 */ 190 static const struct execsw **execsw; 191 192 #ifndef _SYS_SYSPROTO_H_ 193 struct execve_args { 194 char *fname; 195 char **argv; 196 char **envv; 197 }; 198 #endif 199 200 int 201 sys_execve(struct thread *td, struct execve_args *uap) 202 { 203 struct image_args args; 204 struct vmspace *oldvmspace; 205 int error; 206 207 error = pre_execve(td, &oldvmspace); 208 if (error != 0) 209 return (error); 210 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 211 uap->argv, uap->envv); 212 if (error == 0) 213 error = kern_execve(td, &args, NULL); 214 post_execve(td, error, oldvmspace); 215 return (error); 216 } 217 218 #ifndef _SYS_SYSPROTO_H_ 219 struct fexecve_args { 220 int fd; 221 char **argv; 222 char **envv; 223 } 224 #endif 225 int 226 sys_fexecve(struct thread *td, struct fexecve_args *uap) 227 { 228 struct image_args args; 229 struct vmspace *oldvmspace; 230 int error; 231 232 error = pre_execve(td, &oldvmspace); 233 if (error != 0) 234 return (error); 235 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 236 uap->argv, uap->envv); 237 if (error == 0) { 238 args.fd = uap->fd; 239 error = kern_execve(td, &args, NULL); 240 } 241 post_execve(td, error, oldvmspace); 242 return (error); 243 } 244 245 #ifndef _SYS_SYSPROTO_H_ 246 struct __mac_execve_args { 247 char *fname; 248 char **argv; 249 char **envv; 250 struct mac *mac_p; 251 }; 252 #endif 253 254 int 255 sys___mac_execve(struct thread *td, struct __mac_execve_args *uap) 256 { 257 #ifdef MAC 258 struct image_args args; 259 struct vmspace *oldvmspace; 260 int error; 261 262 error = pre_execve(td, &oldvmspace); 263 if (error != 0) 264 return (error); 265 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 266 uap->argv, uap->envv); 267 if (error == 0) 268 error = kern_execve(td, &args, uap->mac_p); 269 post_execve(td, error, oldvmspace); 270 return (error); 271 #else 272 return (ENOSYS); 273 #endif 274 } 275 276 int 277 pre_execve(struct thread *td, struct vmspace **oldvmspace) 278 { 279 struct proc *p; 280 int error; 281 282 KASSERT(td == curthread, ("non-current thread %p", td)); 283 error = 0; 284 p = td->td_proc; 285 if ((p->p_flag & P_HADTHREADS) != 0) { 286 PROC_LOCK(p); 287 if (thread_single(p, SINGLE_BOUNDARY) != 0) 288 error = ERESTART; 289 PROC_UNLOCK(p); 290 } 291 KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0, 292 ("nested execve")); 293 *oldvmspace = p->p_vmspace; 294 return (error); 295 } 296 297 void 298 post_execve(struct thread *td, int error, struct vmspace *oldvmspace) 299 { 300 struct proc *p; 301 302 KASSERT(td == curthread, ("non-current thread %p", td)); 303 p = td->td_proc; 304 if ((p->p_flag & P_HADTHREADS) != 0) { 305 PROC_LOCK(p); 306 /* 307 * If success, we upgrade to SINGLE_EXIT state to 308 * force other threads to suicide. 309 */ 310 if (error == 0) 311 thread_single(p, SINGLE_EXIT); 312 else 313 thread_single_end(p, SINGLE_BOUNDARY); 314 PROC_UNLOCK(p); 315 } 316 if ((td->td_pflags & TDP_EXECVMSPC) != 0) { 317 KASSERT(p->p_vmspace != oldvmspace, 318 ("oldvmspace still used")); 319 vmspace_free(oldvmspace); 320 td->td_pflags &= ~TDP_EXECVMSPC; 321 } 322 } 323 324 /* 325 * XXX: kern_execve has the astonishing property of not always returning to 326 * the caller. If sufficiently bad things happen during the call to 327 * do_execve(), it can end up calling exit1(); as a result, callers must 328 * avoid doing anything which they might need to undo (e.g., allocating 329 * memory). 330 */ 331 int 332 kern_execve(struct thread *td, struct image_args *args, struct mac *mac_p) 333 { 334 335 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 336 args->begin_envv - args->begin_argv); 337 AUDIT_ARG_ENVV(args->begin_envv, args->envc, 338 args->endp - args->begin_envv); 339 return (do_execve(td, args, mac_p)); 340 } 341 342 /* 343 * In-kernel implementation of execve(). All arguments are assumed to be 344 * userspace pointers from the passed thread. 345 */ 346 static int 347 do_execve(td, args, mac_p) 348 struct thread *td; 349 struct image_args *args; 350 struct mac *mac_p; 351 { 352 struct proc *p = td->td_proc; 353 struct nameidata nd; 354 struct ucred *newcred = NULL, *oldcred; 355 struct uidinfo *euip = NULL; 356 register_t *stack_base; 357 int error, i; 358 struct image_params image_params, *imgp; 359 struct vattr attr; 360 int (*img_first)(struct image_params *); 361 struct pargs *oldargs = NULL, *newargs = NULL; 362 struct sigacts *oldsigacts, *newsigacts; 363 #ifdef KTRACE 364 struct vnode *tracevp = NULL; 365 struct ucred *tracecred = NULL; 366 #endif 367 struct vnode *oldtextvp = NULL, *newtextvp; 368 cap_rights_t rights; 369 int credential_changing; 370 int textset; 371 #ifdef MAC 372 struct label *interpvplabel = NULL; 373 int will_transition; 374 #endif 375 #ifdef HWPMC_HOOKS 376 struct pmckern_procexec pe; 377 #endif 378 static const char fexecv_proc_title[] = "(fexecv)"; 379 380 imgp = &image_params; 381 382 /* 383 * Lock the process and set the P_INEXEC flag to indicate that 384 * it should be left alone until we're done here. This is 385 * necessary to avoid race conditions - e.g. in ptrace() - 386 * that might allow a local user to illicitly obtain elevated 387 * privileges. 388 */ 389 PROC_LOCK(p); 390 KASSERT((p->p_flag & P_INEXEC) == 0, 391 ("%s(): process already has P_INEXEC flag", __func__)); 392 p->p_flag |= P_INEXEC; 393 PROC_UNLOCK(p); 394 395 /* 396 * Initialize part of the common data 397 */ 398 bzero(imgp, sizeof(*imgp)); 399 imgp->proc = p; 400 imgp->attr = &attr; 401 imgp->args = args; 402 403 #ifdef MAC 404 error = mac_execve_enter(imgp, mac_p); 405 if (error) 406 goto exec_fail; 407 #endif 408 409 /* 410 * Translate the file name. namei() returns a vnode pointer 411 * in ni_vp amoung other things. 412 * 413 * XXXAUDIT: It would be desirable to also audit the name of the 414 * interpreter if this is an interpreted binary. 415 */ 416 if (args->fname != NULL) { 417 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 418 | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 419 } 420 421 SDT_PROBE1(proc, kernel, , exec, args->fname); 422 423 interpret: 424 if (args->fname != NULL) { 425 #ifdef CAPABILITY_MODE 426 /* 427 * While capability mode can't reach this point via direct 428 * path arguments to execve(), we also don't allow 429 * interpreters to be used in capability mode (for now). 430 * Catch indirect lookups and return a permissions error. 431 */ 432 if (IN_CAPABILITY_MODE(td)) { 433 error = ECAPMODE; 434 goto exec_fail; 435 } 436 #endif 437 error = namei(&nd); 438 if (error) 439 goto exec_fail; 440 441 newtextvp = nd.ni_vp; 442 imgp->vp = newtextvp; 443 } else { 444 AUDIT_ARG_FD(args->fd); 445 /* 446 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 447 */ 448 error = fgetvp_exec(td, args->fd, 449 cap_rights_init(&rights, CAP_FEXECVE), &newtextvp); 450 if (error) 451 goto exec_fail; 452 vn_lock(newtextvp, LK_EXCLUSIVE | LK_RETRY); 453 AUDIT_ARG_VNODE1(newtextvp); 454 imgp->vp = newtextvp; 455 } 456 457 /* 458 * Check file permissions (also 'opens' file) 459 */ 460 error = exec_check_permissions(imgp); 461 if (error) 462 goto exec_fail_dealloc; 463 464 imgp->object = imgp->vp->v_object; 465 if (imgp->object != NULL) 466 vm_object_reference(imgp->object); 467 468 /* 469 * Set VV_TEXT now so no one can write to the executable while we're 470 * activating it. 471 * 472 * Remember if this was set before and unset it in case this is not 473 * actually an executable image. 474 */ 475 textset = VOP_IS_TEXT(imgp->vp); 476 VOP_SET_TEXT(imgp->vp); 477 478 error = exec_map_first_page(imgp); 479 if (error) 480 goto exec_fail_dealloc; 481 482 imgp->proc->p_osrel = 0; 483 /* 484 * If the current process has a special image activator it 485 * wants to try first, call it. For example, emulating shell 486 * scripts differently. 487 */ 488 error = -1; 489 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 490 error = img_first(imgp); 491 492 /* 493 * Loop through the list of image activators, calling each one. 494 * An activator returns -1 if there is no match, 0 on success, 495 * and an error otherwise. 496 */ 497 for (i = 0; error == -1 && execsw[i]; ++i) { 498 if (execsw[i]->ex_imgact == NULL || 499 execsw[i]->ex_imgact == img_first) { 500 continue; 501 } 502 error = (*execsw[i]->ex_imgact)(imgp); 503 } 504 505 if (error) { 506 if (error == -1) { 507 if (textset == 0) 508 VOP_UNSET_TEXT(imgp->vp); 509 error = ENOEXEC; 510 } 511 goto exec_fail_dealloc; 512 } 513 514 /* 515 * Special interpreter operation, cleanup and loop up to try to 516 * activate the interpreter. 517 */ 518 if (imgp->interpreted) { 519 exec_unmap_first_page(imgp); 520 /* 521 * VV_TEXT needs to be unset for scripts. There is a short 522 * period before we determine that something is a script where 523 * VV_TEXT will be set. The vnode lock is held over this 524 * entire period so nothing should illegitimately be blocked. 525 */ 526 VOP_UNSET_TEXT(imgp->vp); 527 /* free name buffer and old vnode */ 528 if (args->fname != NULL) 529 NDFREE(&nd, NDF_ONLY_PNBUF); 530 #ifdef MAC 531 mac_execve_interpreter_enter(newtextvp, &interpvplabel); 532 #endif 533 if (imgp->opened) { 534 VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td); 535 imgp->opened = 0; 536 } 537 vput(newtextvp); 538 vm_object_deallocate(imgp->object); 539 imgp->object = NULL; 540 /* set new name to that of the interpreter */ 541 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 542 UIO_SYSSPACE, imgp->interpreter_name, td); 543 args->fname = imgp->interpreter_name; 544 goto interpret; 545 } 546 547 /* 548 * NB: We unlock the vnode here because it is believed that none 549 * of the sv_copyout_strings/sv_fixup operations require the vnode. 550 */ 551 VOP_UNLOCK(imgp->vp, 0); 552 553 /* 554 * Do the best to calculate the full path to the image file. 555 */ 556 if (imgp->auxargs != NULL && 557 ((args->fname != NULL && args->fname[0] == '/') || 558 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0)) 559 imgp->execpath = args->fname; 560 561 if (disallow_high_osrel && 562 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 563 error = ENOEXEC; 564 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 565 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 566 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 567 goto exec_fail_dealloc; 568 } 569 570 /* ABI enforces the use of Capsicum. Switch into capabilities mode. */ 571 if (SV_PROC_FLAG(p, SV_CAPSICUM)) 572 sys_cap_enter(td, NULL); 573 574 /* 575 * Copy out strings (args and env) and initialize stack base 576 */ 577 if (p->p_sysent->sv_copyout_strings) 578 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 579 else 580 stack_base = exec_copyout_strings(imgp); 581 582 /* 583 * If custom stack fixup routine present for this process 584 * let it do the stack setup. 585 * Else stuff argument count as first item on stack 586 */ 587 if (p->p_sysent->sv_fixup != NULL) 588 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 589 else 590 suword(--stack_base, imgp->args->argc); 591 592 if (args->fdp != NULL) { 593 /* Install a brand new file descriptor table. */ 594 fdinstall_remapped(td, args->fdp); 595 args->fdp = NULL; 596 } else { 597 /* 598 * Keep on using the existing file descriptor table. For 599 * security and other reasons, the file descriptor table 600 * cannot be shared after an exec. 601 */ 602 fdunshare(td); 603 /* close files on exec */ 604 fdcloseexec(td); 605 } 606 607 /* 608 * Malloc things before we need locks. 609 */ 610 i = imgp->args->begin_envv - imgp->args->begin_argv; 611 /* Cache arguments if they fit inside our allowance */ 612 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 613 newargs = pargs_alloc(i); 614 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 615 } 616 617 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 618 619 /* 620 * For security and other reasons, signal handlers cannot 621 * be shared after an exec. The new process gets a copy of the old 622 * handlers. In execsigs(), the new process will have its signals 623 * reset. 624 */ 625 if (sigacts_shared(p->p_sigacts)) { 626 oldsigacts = p->p_sigacts; 627 newsigacts = sigacts_alloc(); 628 sigacts_copy(newsigacts, oldsigacts); 629 } else { 630 oldsigacts = NULL; 631 newsigacts = NULL; /* satisfy gcc */ 632 } 633 634 PROC_LOCK(p); 635 if (oldsigacts) 636 p->p_sigacts = newsigacts; 637 oldcred = p->p_ucred; 638 /* Stop profiling */ 639 stopprofclock(p); 640 641 /* reset caught signals */ 642 execsigs(p); 643 644 /* name this process - nameiexec(p, ndp) */ 645 bzero(p->p_comm, sizeof(p->p_comm)); 646 if (args->fname) 647 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 648 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 649 else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0) 650 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 651 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 652 #ifdef KTR 653 sched_clear_tdname(td); 654 #endif 655 656 /* 657 * mark as execed, wakeup the process that vforked (if any) and tell 658 * it that it now has its own resources back 659 */ 660 p->p_flag |= P_EXEC; 661 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0) 662 p->p_flag2 &= ~P2_NOTRACE; 663 if (p->p_flag & P_PPWAIT) { 664 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 665 cv_broadcast(&p->p_pwait); 666 } 667 668 /* 669 * Implement image setuid/setgid. 670 * 671 * Don't honor setuid/setgid if the filesystem prohibits it or if 672 * the process is being traced. 673 * 674 * We disable setuid/setgid/etc in compatibility mode on the basis 675 * that most setugid applications are not written with that 676 * environment in mind, and will therefore almost certainly operate 677 * incorrectly. In principle there's no reason that setugid 678 * applications might not be useful in capability mode, so we may want 679 * to reconsider this conservative design choice in the future. 680 * 681 * XXXMAC: For the time being, use NOSUID to also prohibit 682 * transitions on the file system. 683 */ 684 credential_changing = 0; 685 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 686 attr.va_uid; 687 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 688 attr.va_gid; 689 #ifdef MAC 690 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 691 interpvplabel, imgp); 692 credential_changing |= will_transition; 693 #endif 694 695 if (credential_changing && 696 #ifdef CAPABILITY_MODE 697 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 698 #endif 699 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 700 (p->p_flag & P_TRACED) == 0) { 701 /* 702 * Turn off syscall tracing for set-id programs, except for 703 * root. Record any set-id flags first to make sure that 704 * we do not regain any tracing during a possible block. 705 */ 706 setsugid(p); 707 708 #ifdef KTRACE 709 if (p->p_tracecred != NULL && 710 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0)) 711 ktrprocexec(p, &tracecred, &tracevp); 712 #endif 713 /* 714 * Close any file descriptors 0..2 that reference procfs, 715 * then make sure file descriptors 0..2 are in use. 716 * 717 * Both fdsetugidsafety() and fdcheckstd() may call functions 718 * taking sleepable locks, so temporarily drop our locks. 719 */ 720 PROC_UNLOCK(p); 721 VOP_UNLOCK(imgp->vp, 0); 722 fdsetugidsafety(td); 723 error = fdcheckstd(td); 724 if (error != 0) 725 goto done1; 726 newcred = crdup(oldcred); 727 euip = uifind(attr.va_uid); 728 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 729 PROC_LOCK(p); 730 /* 731 * Set the new credentials. 732 */ 733 if (attr.va_mode & S_ISUID) 734 change_euid(newcred, euip); 735 if (attr.va_mode & S_ISGID) 736 change_egid(newcred, attr.va_gid); 737 #ifdef MAC 738 if (will_transition) { 739 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 740 interpvplabel, imgp); 741 } 742 #endif 743 /* 744 * Implement correct POSIX saved-id behavior. 745 * 746 * XXXMAC: Note that the current logic will save the 747 * uid and gid if a MAC domain transition occurs, even 748 * though maybe it shouldn't. 749 */ 750 change_svuid(newcred, newcred->cr_uid); 751 change_svgid(newcred, newcred->cr_gid); 752 proc_set_cred(p, newcred); 753 } else { 754 if (oldcred->cr_uid == oldcred->cr_ruid && 755 oldcred->cr_gid == oldcred->cr_rgid) 756 p->p_flag &= ~P_SUGID; 757 /* 758 * Implement correct POSIX saved-id behavior. 759 * 760 * XXX: It's not clear that the existing behavior is 761 * POSIX-compliant. A number of sources indicate that the 762 * saved uid/gid should only be updated if the new ruid is 763 * not equal to the old ruid, or the new euid is not equal 764 * to the old euid and the new euid is not equal to the old 765 * ruid. The FreeBSD code always updates the saved uid/gid. 766 * Also, this code uses the new (replaced) euid and egid as 767 * the source, which may or may not be the right ones to use. 768 */ 769 if (oldcred->cr_svuid != oldcred->cr_uid || 770 oldcred->cr_svgid != oldcred->cr_gid) { 771 PROC_UNLOCK(p); 772 VOP_UNLOCK(imgp->vp, 0); 773 newcred = crdup(oldcred); 774 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 775 PROC_LOCK(p); 776 change_svuid(newcred, newcred->cr_uid); 777 change_svgid(newcred, newcred->cr_gid); 778 proc_set_cred(p, newcred); 779 } 780 } 781 782 /* 783 * Store the vp for use in procfs. This vnode was referenced by namei 784 * or fgetvp_exec. 785 */ 786 oldtextvp = p->p_textvp; 787 p->p_textvp = newtextvp; 788 789 #ifdef KDTRACE_HOOKS 790 /* 791 * Tell the DTrace fasttrap provider about the exec if it 792 * has declared an interest. 793 */ 794 if (dtrace_fasttrap_exec) 795 dtrace_fasttrap_exec(p); 796 #endif 797 798 /* 799 * Notify others that we exec'd, and clear the P_INEXEC flag 800 * as we're now a bona fide freshly-execed process. 801 */ 802 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 803 p->p_flag &= ~P_INEXEC; 804 805 /* clear "fork but no exec" flag, as we _are_ execing */ 806 p->p_acflag &= ~AFORK; 807 808 /* 809 * Free any previous argument cache and replace it with 810 * the new argument cache, if any. 811 */ 812 oldargs = p->p_args; 813 p->p_args = newargs; 814 newargs = NULL; 815 816 #ifdef HWPMC_HOOKS 817 /* 818 * Check if system-wide sampling is in effect or if the 819 * current process is using PMCs. If so, do exec() time 820 * processing. This processing needs to happen AFTER the 821 * P_INEXEC flag is cleared. 822 * 823 * The proc lock needs to be released before taking the PMC 824 * SX. 825 */ 826 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 827 PROC_UNLOCK(p); 828 VOP_UNLOCK(imgp->vp, 0); 829 pe.pm_credentialschanged = credential_changing; 830 pe.pm_entryaddr = imgp->entry_addr; 831 832 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 833 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 834 } else 835 PROC_UNLOCK(p); 836 #else /* !HWPMC_HOOKS */ 837 PROC_UNLOCK(p); 838 #endif 839 840 /* Set values passed into the program in registers. */ 841 if (p->p_sysent->sv_setregs) 842 (*p->p_sysent->sv_setregs)(td, imgp, 843 (u_long)(uintptr_t)stack_base); 844 else 845 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 846 847 vfs_mark_atime(imgp->vp, td->td_ucred); 848 849 SDT_PROBE1(proc, kernel, , exec__success, args->fname); 850 851 VOP_UNLOCK(imgp->vp, 0); 852 done1: 853 /* 854 * Free any resources malloc'd earlier that we didn't use. 855 */ 856 if (euip != NULL) 857 uifree(euip); 858 if (newcred != NULL) 859 crfree(oldcred); 860 861 /* 862 * Handle deferred decrement of ref counts. 863 */ 864 if (oldtextvp != NULL) 865 vrele(oldtextvp); 866 #ifdef KTRACE 867 if (tracevp != NULL) 868 vrele(tracevp); 869 if (tracecred != NULL) 870 crfree(tracecred); 871 #endif 872 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 873 pargs_drop(oldargs); 874 pargs_drop(newargs); 875 if (oldsigacts != NULL) 876 sigacts_free(oldsigacts); 877 878 exec_fail_dealloc: 879 880 /* 881 * free various allocated resources 882 */ 883 if (imgp->firstpage != NULL) 884 exec_unmap_first_page(imgp); 885 886 if (imgp->vp != NULL) { 887 if (args->fname) 888 NDFREE(&nd, NDF_ONLY_PNBUF); 889 if (imgp->opened) 890 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 891 if (error != 0) 892 vput(imgp->vp); 893 else 894 VOP_UNLOCK(imgp->vp, 0); 895 } 896 897 if (imgp->object != NULL) 898 vm_object_deallocate(imgp->object); 899 900 free(imgp->freepath, M_TEMP); 901 902 if (error == 0) { 903 PROC_LOCK(p); 904 td->td_dbgflags |= TDB_EXEC; 905 PROC_UNLOCK(p); 906 907 /* 908 * Stop the process here if its stop event mask has 909 * the S_EXEC bit set. 910 */ 911 STOPEVENT(p, S_EXEC, 0); 912 goto done2; 913 } 914 915 exec_fail: 916 /* we're done here, clear P_INEXEC */ 917 PROC_LOCK(p); 918 p->p_flag &= ~P_INEXEC; 919 PROC_UNLOCK(p); 920 921 SDT_PROBE1(proc, kernel, , exec__failure, error); 922 923 done2: 924 #ifdef MAC 925 mac_execve_exit(imgp); 926 mac_execve_interpreter_exit(interpvplabel); 927 #endif 928 exec_free_args(args); 929 930 if (error && imgp->vmspace_destroyed) { 931 /* sorry, no more process anymore. exit gracefully */ 932 exit1(td, 0, SIGABRT); 933 /* NOT REACHED */ 934 } 935 936 #ifdef KTRACE 937 if (error == 0) 938 ktrprocctor(p); 939 #endif 940 941 return (error); 942 } 943 944 int 945 exec_map_first_page(imgp) 946 struct image_params *imgp; 947 { 948 int rv, i; 949 int initial_pagein; 950 vm_page_t ma[VM_INITIAL_PAGEIN]; 951 vm_object_t object; 952 953 if (imgp->firstpage != NULL) 954 exec_unmap_first_page(imgp); 955 956 object = imgp->vp->v_object; 957 if (object == NULL) 958 return (EACCES); 959 VM_OBJECT_WLOCK(object); 960 #if VM_NRESERVLEVEL > 0 961 vm_object_color(object, 0); 962 #endif 963 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL); 964 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 965 initial_pagein = VM_INITIAL_PAGEIN; 966 if (initial_pagein > object->size) 967 initial_pagein = object->size; 968 for (i = 1; i < initial_pagein; i++) { 969 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 970 if (ma[i]->valid) 971 break; 972 if (vm_page_tryxbusy(ma[i])) 973 break; 974 } else { 975 ma[i] = vm_page_alloc(object, i, 976 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 977 if (ma[i] == NULL) 978 break; 979 } 980 } 981 initial_pagein = i; 982 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 983 if (rv != VM_PAGER_OK) { 984 vm_page_lock(ma[0]); 985 vm_page_free(ma[0]); 986 vm_page_unlock(ma[0]); 987 VM_OBJECT_WUNLOCK(object); 988 return (EIO); 989 } 990 } 991 vm_page_xunbusy(ma[0]); 992 vm_page_lock(ma[0]); 993 vm_page_hold(ma[0]); 994 vm_page_activate(ma[0]); 995 vm_page_unlock(ma[0]); 996 VM_OBJECT_WUNLOCK(object); 997 998 imgp->firstpage = sf_buf_alloc(ma[0], 0); 999 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 1000 1001 return (0); 1002 } 1003 1004 void 1005 exec_unmap_first_page(imgp) 1006 struct image_params *imgp; 1007 { 1008 vm_page_t m; 1009 1010 if (imgp->firstpage != NULL) { 1011 m = sf_buf_page(imgp->firstpage); 1012 sf_buf_free(imgp->firstpage); 1013 imgp->firstpage = NULL; 1014 vm_page_lock(m); 1015 vm_page_unhold(m); 1016 vm_page_unlock(m); 1017 } 1018 } 1019 1020 /* 1021 * Destroy old address space, and allocate a new stack 1022 * The new stack is only SGROWSIZ large because it is grown 1023 * automatically in trap.c. 1024 */ 1025 int 1026 exec_new_vmspace(imgp, sv) 1027 struct image_params *imgp; 1028 struct sysentvec *sv; 1029 { 1030 int error; 1031 struct proc *p = imgp->proc; 1032 struct vmspace *vmspace = p->p_vmspace; 1033 vm_object_t obj; 1034 struct rlimit rlim_stack; 1035 vm_offset_t sv_minuser, stack_addr; 1036 vm_map_t map; 1037 u_long ssiz; 1038 1039 imgp->vmspace_destroyed = 1; 1040 imgp->sysent = sv; 1041 1042 /* May be called with Giant held */ 1043 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1044 1045 /* 1046 * Blow away entire process VM, if address space not shared, 1047 * otherwise, create a new VM space so that other threads are 1048 * not disrupted 1049 */ 1050 map = &vmspace->vm_map; 1051 if (map_at_zero) 1052 sv_minuser = sv->sv_minuser; 1053 else 1054 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1055 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1056 vm_map_max(map) == sv->sv_maxuser) { 1057 shmexit(vmspace); 1058 pmap_remove_pages(vmspace_pmap(vmspace)); 1059 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1060 } else { 1061 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1062 if (error) 1063 return (error); 1064 vmspace = p->p_vmspace; 1065 map = &vmspace->vm_map; 1066 } 1067 1068 /* Map a shared page */ 1069 obj = sv->sv_shared_page_obj; 1070 if (obj != NULL) { 1071 vm_object_reference(obj); 1072 error = vm_map_fixed(map, obj, 0, 1073 sv->sv_shared_page_base, sv->sv_shared_page_len, 1074 VM_PROT_READ | VM_PROT_EXECUTE, 1075 VM_PROT_READ | VM_PROT_EXECUTE, 1076 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1077 if (error) { 1078 vm_object_deallocate(obj); 1079 return (error); 1080 } 1081 } 1082 1083 /* Allocate a new stack */ 1084 if (imgp->stack_sz != 0) { 1085 ssiz = trunc_page(imgp->stack_sz); 1086 PROC_LOCK(p); 1087 lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack); 1088 PROC_UNLOCK(p); 1089 if (ssiz > rlim_stack.rlim_max) 1090 ssiz = rlim_stack.rlim_max; 1091 if (ssiz > rlim_stack.rlim_cur) { 1092 rlim_stack.rlim_cur = ssiz; 1093 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack); 1094 } 1095 } else if (sv->sv_maxssiz != NULL) { 1096 ssiz = *sv->sv_maxssiz; 1097 } else { 1098 ssiz = maxssiz; 1099 } 1100 stack_addr = sv->sv_usrstack - ssiz; 1101 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1102 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1103 sv->sv_stackprot, 1104 VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1105 if (error) 1106 return (error); 1107 1108 /* 1109 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they 1110 * are still used to enforce the stack rlimit on the process stack. 1111 */ 1112 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1113 vmspace->vm_maxsaddr = (char *)stack_addr; 1114 1115 return (0); 1116 } 1117 1118 /* 1119 * Copy out argument and environment strings from the old process address 1120 * space into the temporary string buffer. 1121 */ 1122 int 1123 exec_copyin_args(struct image_args *args, char *fname, 1124 enum uio_seg segflg, char **argv, char **envv) 1125 { 1126 u_long argp, envp; 1127 int error; 1128 size_t length; 1129 1130 bzero(args, sizeof(*args)); 1131 if (argv == NULL) 1132 return (EFAULT); 1133 1134 /* 1135 * Allocate demand-paged memory for the file name, argument, and 1136 * environment strings. 1137 */ 1138 error = exec_alloc_args(args); 1139 if (error != 0) 1140 return (error); 1141 1142 /* 1143 * Copy the file name. 1144 */ 1145 if (fname != NULL) { 1146 args->fname = args->buf; 1147 error = (segflg == UIO_SYSSPACE) ? 1148 copystr(fname, args->fname, PATH_MAX, &length) : 1149 copyinstr(fname, args->fname, PATH_MAX, &length); 1150 if (error != 0) 1151 goto err_exit; 1152 } else 1153 length = 0; 1154 1155 args->begin_argv = args->buf + length; 1156 args->endp = args->begin_argv; 1157 args->stringspace = ARG_MAX; 1158 1159 /* 1160 * extract arguments first 1161 */ 1162 for (;;) { 1163 error = fueword(argv++, &argp); 1164 if (error == -1) { 1165 error = EFAULT; 1166 goto err_exit; 1167 } 1168 if (argp == 0) 1169 break; 1170 error = copyinstr((void *)(uintptr_t)argp, args->endp, 1171 args->stringspace, &length); 1172 if (error != 0) { 1173 if (error == ENAMETOOLONG) 1174 error = E2BIG; 1175 goto err_exit; 1176 } 1177 args->stringspace -= length; 1178 args->endp += length; 1179 args->argc++; 1180 } 1181 1182 args->begin_envv = args->endp; 1183 1184 /* 1185 * extract environment strings 1186 */ 1187 if (envv) { 1188 for (;;) { 1189 error = fueword(envv++, &envp); 1190 if (error == -1) { 1191 error = EFAULT; 1192 goto err_exit; 1193 } 1194 if (envp == 0) 1195 break; 1196 error = copyinstr((void *)(uintptr_t)envp, 1197 args->endp, args->stringspace, &length); 1198 if (error != 0) { 1199 if (error == ENAMETOOLONG) 1200 error = E2BIG; 1201 goto err_exit; 1202 } 1203 args->stringspace -= length; 1204 args->endp += length; 1205 args->envc++; 1206 } 1207 } 1208 1209 return (0); 1210 1211 err_exit: 1212 exec_free_args(args); 1213 return (error); 1214 } 1215 1216 int 1217 exec_copyin_data_fds(struct thread *td, struct image_args *args, 1218 const void *data, size_t datalen, const int *fds, size_t fdslen) 1219 { 1220 struct filedesc *ofdp; 1221 const char *p; 1222 int *kfds; 1223 int error; 1224 1225 memset(args, '\0', sizeof(*args)); 1226 ofdp = td->td_proc->p_fd; 1227 if (datalen >= ARG_MAX || fdslen > ofdp->fd_lastfile + 1) 1228 return (E2BIG); 1229 error = exec_alloc_args(args); 1230 if (error != 0) 1231 return (error); 1232 1233 args->begin_argv = args->buf; 1234 args->stringspace = ARG_MAX; 1235 1236 if (datalen > 0) { 1237 /* 1238 * Argument buffer has been provided. Copy it into the 1239 * kernel as a single string and add a terminating null 1240 * byte. 1241 */ 1242 error = copyin(data, args->begin_argv, datalen); 1243 if (error != 0) 1244 goto err_exit; 1245 args->begin_argv[datalen] = '\0'; 1246 args->endp = args->begin_argv + datalen + 1; 1247 args->stringspace -= datalen + 1; 1248 1249 /* 1250 * Traditional argument counting. Count the number of 1251 * null bytes. 1252 */ 1253 for (p = args->begin_argv; p < args->endp; ++p) 1254 if (*p == '\0') 1255 ++args->argc; 1256 } else { 1257 /* No argument buffer provided. */ 1258 args->endp = args->begin_argv; 1259 } 1260 /* There are no environment variables. */ 1261 args->begin_envv = args->endp; 1262 1263 /* Create new file descriptor table. */ 1264 kfds = malloc(fdslen * sizeof(int), M_TEMP, M_WAITOK); 1265 error = copyin(fds, kfds, fdslen * sizeof(int)); 1266 if (error != 0) { 1267 free(kfds, M_TEMP); 1268 goto err_exit; 1269 } 1270 error = fdcopy_remapped(ofdp, kfds, fdslen, &args->fdp); 1271 free(kfds, M_TEMP); 1272 if (error != 0) 1273 goto err_exit; 1274 1275 return (0); 1276 err_exit: 1277 exec_free_args(args); 1278 return (error); 1279 } 1280 1281 /* 1282 * Allocate temporary demand-paged, zero-filled memory for the file name, 1283 * argument, and environment strings. Returns zero if the allocation succeeds 1284 * and ENOMEM otherwise. 1285 */ 1286 int 1287 exec_alloc_args(struct image_args *args) 1288 { 1289 1290 args->buf = (char *)kmap_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 1291 return (args->buf != NULL ? 0 : ENOMEM); 1292 } 1293 1294 void 1295 exec_free_args(struct image_args *args) 1296 { 1297 1298 if (args->buf != NULL) { 1299 kmap_free_wakeup(exec_map, (vm_offset_t)args->buf, 1300 PATH_MAX + ARG_MAX); 1301 args->buf = NULL; 1302 } 1303 if (args->fname_buf != NULL) { 1304 free(args->fname_buf, M_TEMP); 1305 args->fname_buf = NULL; 1306 } 1307 if (args->fdp != NULL) 1308 fdescfree_remapped(args->fdp); 1309 } 1310 1311 /* 1312 * Copy strings out to the new process address space, constructing new arg 1313 * and env vector tables. Return a pointer to the base so that it can be used 1314 * as the initial stack pointer. 1315 */ 1316 register_t * 1317 exec_copyout_strings(imgp) 1318 struct image_params *imgp; 1319 { 1320 int argc, envc; 1321 char **vectp; 1322 char *stringp; 1323 uintptr_t destp; 1324 register_t *stack_base; 1325 struct ps_strings *arginfo; 1326 struct proc *p; 1327 size_t execpath_len; 1328 int szsigcode, szps; 1329 char canary[sizeof(long) * 8]; 1330 1331 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1332 /* 1333 * Calculate string base and vector table pointers. 1334 * Also deal with signal trampoline code for this exec type. 1335 */ 1336 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1337 execpath_len = strlen(imgp->execpath) + 1; 1338 else 1339 execpath_len = 0; 1340 p = imgp->proc; 1341 szsigcode = 0; 1342 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1343 if (p->p_sysent->sv_sigcode_base == 0) { 1344 if (p->p_sysent->sv_szsigcode != NULL) 1345 szsigcode = *(p->p_sysent->sv_szsigcode); 1346 } 1347 destp = (uintptr_t)arginfo; 1348 1349 /* 1350 * install sigcode 1351 */ 1352 if (szsigcode != 0) { 1353 destp -= szsigcode; 1354 destp = rounddown2(destp, sizeof(void *)); 1355 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode); 1356 } 1357 1358 /* 1359 * Copy the image path for the rtld. 1360 */ 1361 if (execpath_len != 0) { 1362 destp -= execpath_len; 1363 imgp->execpathp = destp; 1364 copyout(imgp->execpath, (void *)destp, execpath_len); 1365 } 1366 1367 /* 1368 * Prepare the canary for SSP. 1369 */ 1370 arc4rand(canary, sizeof(canary), 0); 1371 destp -= sizeof(canary); 1372 imgp->canary = destp; 1373 copyout(canary, (void *)destp, sizeof(canary)); 1374 imgp->canarylen = sizeof(canary); 1375 1376 /* 1377 * Prepare the pagesizes array. 1378 */ 1379 destp -= szps; 1380 destp = rounddown2(destp, sizeof(void *)); 1381 imgp->pagesizes = destp; 1382 copyout(pagesizes, (void *)destp, szps); 1383 imgp->pagesizeslen = szps; 1384 1385 destp -= ARG_MAX - imgp->args->stringspace; 1386 destp = rounddown2(destp, sizeof(void *)); 1387 1388 /* 1389 * If we have a valid auxargs ptr, prepare some room 1390 * on the stack. 1391 */ 1392 if (imgp->auxargs) { 1393 /* 1394 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1395 * lower compatibility. 1396 */ 1397 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1398 (AT_COUNT * 2); 1399 /* 1400 * The '+ 2' is for the null pointers at the end of each of 1401 * the arg and env vector sets,and imgp->auxarg_size is room 1402 * for argument of Runtime loader. 1403 */ 1404 vectp = (char **)(destp - (imgp->args->argc + 1405 imgp->args->envc + 2 + imgp->auxarg_size) 1406 * sizeof(char *)); 1407 } else { 1408 /* 1409 * The '+ 2' is for the null pointers at the end of each of 1410 * the arg and env vector sets 1411 */ 1412 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc 1413 + 2) * sizeof(char *)); 1414 } 1415 1416 /* 1417 * vectp also becomes our initial stack base 1418 */ 1419 stack_base = (register_t *)vectp; 1420 1421 stringp = imgp->args->begin_argv; 1422 argc = imgp->args->argc; 1423 envc = imgp->args->envc; 1424 1425 /* 1426 * Copy out strings - arguments and environment. 1427 */ 1428 copyout(stringp, (void *)destp, ARG_MAX - imgp->args->stringspace); 1429 1430 /* 1431 * Fill in "ps_strings" struct for ps, w, etc. 1432 */ 1433 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1434 suword32(&arginfo->ps_nargvstr, argc); 1435 1436 /* 1437 * Fill in argument portion of vector table. 1438 */ 1439 for (; argc > 0; --argc) { 1440 suword(vectp++, (long)(intptr_t)destp); 1441 while (*stringp++ != 0) 1442 destp++; 1443 destp++; 1444 } 1445 1446 /* a null vector table pointer separates the argp's from the envp's */ 1447 suword(vectp++, 0); 1448 1449 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1450 suword32(&arginfo->ps_nenvstr, envc); 1451 1452 /* 1453 * Fill in environment portion of vector table. 1454 */ 1455 for (; envc > 0; --envc) { 1456 suword(vectp++, (long)(intptr_t)destp); 1457 while (*stringp++ != 0) 1458 destp++; 1459 destp++; 1460 } 1461 1462 /* end of vector table is a null pointer */ 1463 suword(vectp, 0); 1464 1465 return (stack_base); 1466 } 1467 1468 /* 1469 * Check permissions of file to execute. 1470 * Called with imgp->vp locked. 1471 * Return 0 for success or error code on failure. 1472 */ 1473 int 1474 exec_check_permissions(imgp) 1475 struct image_params *imgp; 1476 { 1477 struct vnode *vp = imgp->vp; 1478 struct vattr *attr = imgp->attr; 1479 struct thread *td; 1480 int error, writecount; 1481 1482 td = curthread; 1483 1484 /* Get file attributes */ 1485 error = VOP_GETATTR(vp, attr, td->td_ucred); 1486 if (error) 1487 return (error); 1488 1489 #ifdef MAC 1490 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1491 if (error) 1492 return (error); 1493 #endif 1494 1495 /* 1496 * 1) Check if file execution is disabled for the filesystem that 1497 * this file resides on. 1498 * 2) Ensure that at least one execute bit is on. Otherwise, a 1499 * privileged user will always succeed, and we don't want this 1500 * to happen unless the file really is executable. 1501 * 3) Ensure that the file is a regular file. 1502 */ 1503 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1504 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1505 (attr->va_type != VREG)) 1506 return (EACCES); 1507 1508 /* 1509 * Zero length files can't be exec'd 1510 */ 1511 if (attr->va_size == 0) 1512 return (ENOEXEC); 1513 1514 /* 1515 * Check for execute permission to file based on current credentials. 1516 */ 1517 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1518 if (error) 1519 return (error); 1520 1521 /* 1522 * Check number of open-for-writes on the file and deny execution 1523 * if there are any. 1524 */ 1525 error = VOP_GET_WRITECOUNT(vp, &writecount); 1526 if (error != 0) 1527 return (error); 1528 if (writecount != 0) 1529 return (ETXTBSY); 1530 1531 /* 1532 * Call filesystem specific open routine (which does nothing in the 1533 * general case). 1534 */ 1535 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1536 if (error == 0) 1537 imgp->opened = 1; 1538 return (error); 1539 } 1540 1541 /* 1542 * Exec handler registration 1543 */ 1544 int 1545 exec_register(execsw_arg) 1546 const struct execsw *execsw_arg; 1547 { 1548 const struct execsw **es, **xs, **newexecsw; 1549 int count = 2; /* New slot and trailing NULL */ 1550 1551 if (execsw) 1552 for (es = execsw; *es; es++) 1553 count++; 1554 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1555 if (newexecsw == NULL) 1556 return (ENOMEM); 1557 xs = newexecsw; 1558 if (execsw) 1559 for (es = execsw; *es; es++) 1560 *xs++ = *es; 1561 *xs++ = execsw_arg; 1562 *xs = NULL; 1563 if (execsw) 1564 free(execsw, M_TEMP); 1565 execsw = newexecsw; 1566 return (0); 1567 } 1568 1569 int 1570 exec_unregister(execsw_arg) 1571 const struct execsw *execsw_arg; 1572 { 1573 const struct execsw **es, **xs, **newexecsw; 1574 int count = 1; 1575 1576 if (execsw == NULL) 1577 panic("unregister with no handlers left?\n"); 1578 1579 for (es = execsw; *es; es++) { 1580 if (*es == execsw_arg) 1581 break; 1582 } 1583 if (*es == NULL) 1584 return (ENOENT); 1585 for (es = execsw; *es; es++) 1586 if (*es != execsw_arg) 1587 count++; 1588 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1589 if (newexecsw == NULL) 1590 return (ENOMEM); 1591 xs = newexecsw; 1592 for (es = execsw; *es; es++) 1593 if (*es != execsw_arg) 1594 *xs++ = *es; 1595 *xs = NULL; 1596 if (execsw) 1597 free(execsw, M_TEMP); 1598 execsw = newexecsw; 1599 return (0); 1600 } 1601