Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_exec.c
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1 /*- 2 * Copyright (c) 1993, David Greenman 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 #include "opt_capsicum.h" 31 #include "opt_hwpmc_hooks.h" 32 #include "opt_kdtrace.h" 33 #include "opt_ktrace.h" 34 #include "opt_vm.h" 35 36 #include <sys/param.h> 37 #include <sys/capability.h> 38 #include <sys/systm.h> 39 #include <sys/capability.h> 40 #include <sys/eventhandler.h> 41 #include <sys/lock.h> 42 #include <sys/mutex.h> 43 #include <sys/sysproto.h> 44 #include <sys/signalvar.h> 45 #include <sys/kernel.h> 46 #include <sys/mount.h> 47 #include <sys/filedesc.h> 48 #include <sys/fcntl.h> 49 #include <sys/acct.h> 50 #include <sys/exec.h> 51 #include <sys/imgact.h> 52 #include <sys/imgact_elf.h> 53 #include <sys/wait.h> 54 #include <sys/malloc.h> 55 #include <sys/priv.h> 56 #include <sys/proc.h> 57 #include <sys/pioctl.h> 58 #include <sys/namei.h> 59 #include <sys/resourcevar.h> 60 #include <sys/sched.h> 61 #include <sys/sdt.h> 62 #include <sys/sf_buf.h> 63 #include <sys/syscallsubr.h> 64 #include <sys/sysent.h> 65 #include <sys/shm.h> 66 #include <sys/sysctl.h> 67 #include <sys/vnode.h> 68 #include <sys/stat.h> 69 #ifdef KTRACE 70 #include <sys/ktrace.h> 71 #endif 72 73 #include <vm/vm.h> 74 #include <vm/vm_param.h> 75 #include <vm/pmap.h> 76 #include <vm/vm_page.h> 77 #include <vm/vm_map.h> 78 #include <vm/vm_kern.h> 79 #include <vm/vm_extern.h> 80 #include <vm/vm_object.h> 81 #include <vm/vm_pager.h> 82 83 #ifdef HWPMC_HOOKS 84 #include <sys/pmckern.h> 85 #endif 86 87 #include <machine/reg.h> 88 89 #include <security/audit/audit.h> 90 #include <security/mac/mac_framework.h> 91 92 #ifdef KDTRACE_HOOKS 93 #include <sys/dtrace_bsd.h> 94 dtrace_execexit_func_t dtrace_fasttrap_exec; 95 #endif 96 97 SDT_PROVIDER_DECLARE(proc); 98 SDT_PROBE_DEFINE1(proc, kernel, , exec, "char *"); 99 SDT_PROBE_DEFINE1(proc, kernel, , exec__failure, "int"); 100 SDT_PROBE_DEFINE1(proc, kernel, , exec__success, "char *"); 101 102 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 103 104 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 105 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 106 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 107 static int do_execve(struct thread *td, struct image_args *args, 108 struct mac *mac_p); 109 110 /* XXX This should be vm_size_t. */ 111 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD, 112 NULL, 0, sysctl_kern_ps_strings, "LU", ""); 113 114 /* XXX This should be vm_size_t. */ 115 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 116 CTLFLAG_CAPRD, NULL, 0, sysctl_kern_usrstack, "LU", ""); 117 118 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 119 NULL, 0, sysctl_kern_stackprot, "I", ""); 120 121 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 122 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 123 &ps_arg_cache_limit, 0, ""); 124 125 static int disallow_high_osrel; 126 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW, 127 &disallow_high_osrel, 0, 128 "Disallow execution of binaries built for higher version of the world"); 129 130 static int map_at_zero = 0; 131 TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero); 132 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &map_at_zero, 0, 133 "Permit processes to map an object at virtual address 0."); 134 135 static int 136 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 137 { 138 struct proc *p; 139 int error; 140 141 p = curproc; 142 #ifdef SCTL_MASK32 143 if (req->flags & SCTL_MASK32) { 144 unsigned int val; 145 val = (unsigned int)p->p_sysent->sv_psstrings; 146 error = SYSCTL_OUT(req, &val, sizeof(val)); 147 } else 148 #endif 149 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 150 sizeof(p->p_sysent->sv_psstrings)); 151 return error; 152 } 153 154 static int 155 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 156 { 157 struct proc *p; 158 int error; 159 160 p = curproc; 161 #ifdef SCTL_MASK32 162 if (req->flags & SCTL_MASK32) { 163 unsigned int val; 164 val = (unsigned int)p->p_sysent->sv_usrstack; 165 error = SYSCTL_OUT(req, &val, sizeof(val)); 166 } else 167 #endif 168 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 169 sizeof(p->p_sysent->sv_usrstack)); 170 return error; 171 } 172 173 static int 174 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 175 { 176 struct proc *p; 177 178 p = curproc; 179 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 180 sizeof(p->p_sysent->sv_stackprot))); 181 } 182 183 /* 184 * Each of the items is a pointer to a `const struct execsw', hence the 185 * double pointer here. 186 */ 187 static const struct execsw **execsw; 188 189 #ifndef _SYS_SYSPROTO_H_ 190 struct execve_args { 191 char *fname; 192 char **argv; 193 char **envv; 194 }; 195 #endif 196 197 int 198 sys_execve(td, uap) 199 struct thread *td; 200 struct execve_args /* { 201 char *fname; 202 char **argv; 203 char **envv; 204 } */ *uap; 205 { 206 int error; 207 struct image_args args; 208 209 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 210 uap->argv, uap->envv); 211 if (error == 0) 212 error = kern_execve(td, &args, NULL); 213 return (error); 214 } 215 216 #ifndef _SYS_SYSPROTO_H_ 217 struct fexecve_args { 218 int fd; 219 char **argv; 220 char **envv; 221 } 222 #endif 223 int 224 sys_fexecve(struct thread *td, struct fexecve_args *uap) 225 { 226 int error; 227 struct image_args args; 228 229 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 230 uap->argv, uap->envv); 231 if (error == 0) { 232 args.fd = uap->fd; 233 error = kern_execve(td, &args, NULL); 234 } 235 return (error); 236 } 237 238 #ifndef _SYS_SYSPROTO_H_ 239 struct __mac_execve_args { 240 char *fname; 241 char **argv; 242 char **envv; 243 struct mac *mac_p; 244 }; 245 #endif 246 247 int 248 sys___mac_execve(td, uap) 249 struct thread *td; 250 struct __mac_execve_args /* { 251 char *fname; 252 char **argv; 253 char **envv; 254 struct mac *mac_p; 255 } */ *uap; 256 { 257 #ifdef MAC 258 int error; 259 struct image_args args; 260 261 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 262 uap->argv, uap->envv); 263 if (error == 0) 264 error = kern_execve(td, &args, uap->mac_p); 265 return (error); 266 #else 267 return (ENOSYS); 268 #endif 269 } 270 271 /* 272 * XXX: kern_execve has the astonishing property of not always returning to 273 * the caller. If sufficiently bad things happen during the call to 274 * do_execve(), it can end up calling exit1(); as a result, callers must 275 * avoid doing anything which they might need to undo (e.g., allocating 276 * memory). 277 */ 278 int 279 kern_execve(td, args, mac_p) 280 struct thread *td; 281 struct image_args *args; 282 struct mac *mac_p; 283 { 284 struct proc *p = td->td_proc; 285 struct vmspace *oldvmspace; 286 int error; 287 288 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 289 args->begin_envv - args->begin_argv); 290 AUDIT_ARG_ENVV(args->begin_envv, args->envc, 291 args->endp - args->begin_envv); 292 if (p->p_flag & P_HADTHREADS) { 293 PROC_LOCK(p); 294 if (thread_single(SINGLE_BOUNDARY)) { 295 PROC_UNLOCK(p); 296 exec_free_args(args); 297 return (ERESTART); /* Try again later. */ 298 } 299 PROC_UNLOCK(p); 300 } 301 302 KASSERT((td->td_pflags & TDP_EXECVMSPC) == 0, ("nested execve")); 303 oldvmspace = td->td_proc->p_vmspace; 304 error = do_execve(td, args, mac_p); 305 306 if (p->p_flag & P_HADTHREADS) { 307 PROC_LOCK(p); 308 /* 309 * If success, we upgrade to SINGLE_EXIT state to 310 * force other threads to suicide. 311 */ 312 if (error == 0) 313 thread_single(SINGLE_EXIT); 314 else 315 thread_single_end(); 316 PROC_UNLOCK(p); 317 } 318 if ((td->td_pflags & TDP_EXECVMSPC) != 0) { 319 KASSERT(td->td_proc->p_vmspace != oldvmspace, 320 ("oldvmspace still used")); 321 vmspace_free(oldvmspace); 322 td->td_pflags &= ~TDP_EXECVMSPC; 323 } 324 325 return (error); 326 } 327 328 /* 329 * In-kernel implementation of execve(). All arguments are assumed to be 330 * userspace pointers from the passed thread. 331 */ 332 static int 333 do_execve(td, args, mac_p) 334 struct thread *td; 335 struct image_args *args; 336 struct mac *mac_p; 337 { 338 struct proc *p = td->td_proc; 339 struct nameidata nd; 340 struct ucred *newcred = NULL, *oldcred; 341 struct uidinfo *euip; 342 register_t *stack_base; 343 int error, i; 344 struct image_params image_params, *imgp; 345 struct vattr attr; 346 int (*img_first)(struct image_params *); 347 struct pargs *oldargs = NULL, *newargs = NULL; 348 struct sigacts *oldsigacts, *newsigacts; 349 #ifdef KTRACE 350 struct vnode *tracevp = NULL; 351 struct ucred *tracecred = NULL; 352 #endif 353 struct vnode *textvp = NULL, *binvp = NULL; 354 int credential_changing; 355 int vfslocked; 356 int textset; 357 #ifdef MAC 358 struct label *interpvplabel = NULL; 359 int will_transition; 360 #endif 361 #ifdef HWPMC_HOOKS 362 struct pmckern_procexec pe; 363 #endif 364 static const char fexecv_proc_title[] = "(fexecv)"; 365 366 vfslocked = 0; 367 imgp = &image_params; 368 369 /* 370 * Lock the process and set the P_INEXEC flag to indicate that 371 * it should be left alone until we're done here. This is 372 * necessary to avoid race conditions - e.g. in ptrace() - 373 * that might allow a local user to illicitly obtain elevated 374 * privileges. 375 */ 376 PROC_LOCK(p); 377 KASSERT((p->p_flag & P_INEXEC) == 0, 378 ("%s(): process already has P_INEXEC flag", __func__)); 379 p->p_flag |= P_INEXEC; 380 PROC_UNLOCK(p); 381 382 /* 383 * Initialize part of the common data 384 */ 385 imgp->proc = p; 386 imgp->execlabel = NULL; 387 imgp->attr = &attr; 388 imgp->entry_addr = 0; 389 imgp->reloc_base = 0; 390 imgp->vmspace_destroyed = 0; 391 imgp->interpreted = 0; 392 imgp->opened = 0; 393 imgp->interpreter_name = NULL; 394 imgp->auxargs = NULL; 395 imgp->vp = NULL; 396 imgp->object = NULL; 397 imgp->firstpage = NULL; 398 imgp->ps_strings = 0; 399 imgp->auxarg_size = 0; 400 imgp->args = args; 401 imgp->execpath = imgp->freepath = NULL; 402 imgp->execpathp = 0; 403 imgp->canary = 0; 404 imgp->canarylen = 0; 405 imgp->pagesizes = 0; 406 imgp->pagesizeslen = 0; 407 imgp->stack_prot = 0; 408 409 #ifdef MAC 410 error = mac_execve_enter(imgp, mac_p); 411 if (error) 412 goto exec_fail; 413 #endif 414 415 imgp->image_header = NULL; 416 417 /* 418 * Translate the file name. namei() returns a vnode pointer 419 * in ni_vp amoung other things. 420 * 421 * XXXAUDIT: It would be desirable to also audit the name of the 422 * interpreter if this is an interpreted binary. 423 */ 424 if (args->fname != NULL) { 425 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 426 | MPSAFE | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 427 } 428 429 SDT_PROBE1(proc, kernel, , exec, args->fname); 430 431 interpret: 432 if (args->fname != NULL) { 433 #ifdef CAPABILITY_MODE 434 /* 435 * While capability mode can't reach this point via direct 436 * path arguments to execve(), we also don't allow 437 * interpreters to be used in capability mode (for now). 438 * Catch indirect lookups and return a permissions error. 439 */ 440 if (IN_CAPABILITY_MODE(td)) { 441 error = ECAPMODE; 442 goto exec_fail; 443 } 444 #endif 445 error = namei(&nd); 446 if (error) 447 goto exec_fail; 448 449 vfslocked = NDHASGIANT(&nd); 450 binvp = nd.ni_vp; 451 imgp->vp = binvp; 452 } else { 453 AUDIT_ARG_FD(args->fd); 454 /* 455 * Some might argue that CAP_READ and/or CAP_MMAP should also 456 * be required here; such arguments will be entertained. 457 * 458 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 459 */ 460 error = fgetvp_exec(td, args->fd, CAP_FEXECVE, &binvp); 461 if (error) 462 goto exec_fail; 463 vfslocked = VFS_LOCK_GIANT(binvp->v_mount); 464 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY); 465 AUDIT_ARG_VNODE1(binvp); 466 imgp->vp = binvp; 467 } 468 469 /* 470 * Check file permissions (also 'opens' file) 471 */ 472 error = exec_check_permissions(imgp); 473 if (error) 474 goto exec_fail_dealloc; 475 476 imgp->object = imgp->vp->v_object; 477 if (imgp->object != NULL) 478 vm_object_reference(imgp->object); 479 480 /* 481 * Set VV_TEXT now so no one can write to the executable while we're 482 * activating it. 483 * 484 * Remember if this was set before and unset it in case this is not 485 * actually an executable image. 486 */ 487 textset = VOP_IS_TEXT(imgp->vp); 488 VOP_SET_TEXT(imgp->vp); 489 490 error = exec_map_first_page(imgp); 491 if (error) 492 goto exec_fail_dealloc; 493 494 imgp->proc->p_osrel = 0; 495 /* 496 * If the current process has a special image activator it 497 * wants to try first, call it. For example, emulating shell 498 * scripts differently. 499 */ 500 error = -1; 501 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 502 error = img_first(imgp); 503 504 /* 505 * Loop through the list of image activators, calling each one. 506 * An activator returns -1 if there is no match, 0 on success, 507 * and an error otherwise. 508 */ 509 for (i = 0; error == -1 && execsw[i]; ++i) { 510 if (execsw[i]->ex_imgact == NULL || 511 execsw[i]->ex_imgact == img_first) { 512 continue; 513 } 514 error = (*execsw[i]->ex_imgact)(imgp); 515 } 516 517 if (error) { 518 if (error == -1) { 519 if (textset == 0) 520 VOP_UNSET_TEXT(imgp->vp); 521 error = ENOEXEC; 522 } 523 goto exec_fail_dealloc; 524 } 525 526 /* 527 * Special interpreter operation, cleanup and loop up to try to 528 * activate the interpreter. 529 */ 530 if (imgp->interpreted) { 531 exec_unmap_first_page(imgp); 532 /* 533 * VV_TEXT needs to be unset for scripts. There is a short 534 * period before we determine that something is a script where 535 * VV_TEXT will be set. The vnode lock is held over this 536 * entire period so nothing should illegitimately be blocked. 537 */ 538 VOP_UNSET_TEXT(imgp->vp); 539 /* free name buffer and old vnode */ 540 if (args->fname != NULL) 541 NDFREE(&nd, NDF_ONLY_PNBUF); 542 #ifdef MAC 543 mac_execve_interpreter_enter(binvp, &interpvplabel); 544 #endif 545 if (imgp->opened) { 546 VOP_CLOSE(binvp, FREAD, td->td_ucred, td); 547 imgp->opened = 0; 548 } 549 vput(binvp); 550 vm_object_deallocate(imgp->object); 551 imgp->object = NULL; 552 VFS_UNLOCK_GIANT(vfslocked); 553 vfslocked = 0; 554 /* set new name to that of the interpreter */ 555 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME | MPSAFE, 556 UIO_SYSSPACE, imgp->interpreter_name, td); 557 args->fname = imgp->interpreter_name; 558 goto interpret; 559 } 560 561 /* 562 * NB: We unlock the vnode here because it is believed that none 563 * of the sv_copyout_strings/sv_fixup operations require the vnode. 564 */ 565 VOP_UNLOCK(imgp->vp, 0); 566 567 /* 568 * Do the best to calculate the full path to the image file. 569 */ 570 if (imgp->auxargs != NULL && 571 ((args->fname != NULL && args->fname[0] == '/') || 572 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0)) 573 imgp->execpath = args->fname; 574 575 if (disallow_high_osrel && 576 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 577 error = ENOEXEC; 578 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 579 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 580 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 581 goto exec_fail_dealloc; 582 } 583 584 /* 585 * Copy out strings (args and env) and initialize stack base 586 */ 587 if (p->p_sysent->sv_copyout_strings) 588 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 589 else 590 stack_base = exec_copyout_strings(imgp); 591 592 /* 593 * If custom stack fixup routine present for this process 594 * let it do the stack setup. 595 * Else stuff argument count as first item on stack 596 */ 597 if (p->p_sysent->sv_fixup != NULL) 598 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 599 else 600 suword(--stack_base, imgp->args->argc); 601 602 /* 603 * For security and other reasons, the file descriptor table cannot 604 * be shared after an exec. 605 */ 606 fdunshare(p, td); 607 608 /* 609 * Malloc things before we need locks. 610 */ 611 newcred = crget(); 612 euip = uifind(attr.va_uid); 613 i = imgp->args->begin_envv - imgp->args->begin_argv; 614 /* Cache arguments if they fit inside our allowance */ 615 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 616 newargs = pargs_alloc(i); 617 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 618 } 619 620 /* close files on exec */ 621 fdcloseexec(td); 622 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 623 624 /* Get a reference to the vnode prior to locking the proc */ 625 VREF(binvp); 626 627 /* 628 * For security and other reasons, signal handlers cannot 629 * be shared after an exec. The new process gets a copy of the old 630 * handlers. In execsigs(), the new process will have its signals 631 * reset. 632 */ 633 PROC_LOCK(p); 634 oldcred = crcopysafe(p, newcred); 635 if (sigacts_shared(p->p_sigacts)) { 636 oldsigacts = p->p_sigacts; 637 PROC_UNLOCK(p); 638 newsigacts = sigacts_alloc(); 639 sigacts_copy(newsigacts, oldsigacts); 640 PROC_LOCK(p); 641 p->p_sigacts = newsigacts; 642 } else 643 oldsigacts = NULL; 644 645 /* Stop profiling */ 646 stopprofclock(p); 647 648 /* reset caught signals */ 649 execsigs(p); 650 651 /* name this process - nameiexec(p, ndp) */ 652 bzero(p->p_comm, sizeof(p->p_comm)); 653 if (args->fname) 654 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 655 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 656 else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0) 657 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 658 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 659 #ifdef KTR 660 sched_clear_tdname(td); 661 #endif 662 663 /* 664 * mark as execed, wakeup the process that vforked (if any) and tell 665 * it that it now has its own resources back 666 */ 667 p->p_flag |= P_EXEC; 668 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 669 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 670 cv_broadcast(&p->p_pwait); 671 } 672 673 /* 674 * Implement image setuid/setgid. 675 * 676 * Don't honor setuid/setgid if the filesystem prohibits it or if 677 * the process is being traced. 678 * 679 * We disable setuid/setgid/etc in compatibility mode on the basis 680 * that most setugid applications are not written with that 681 * environment in mind, and will therefore almost certainly operate 682 * incorrectly. In principle there's no reason that setugid 683 * applications might not be useful in capability mode, so we may want 684 * to reconsider this conservative design choice in the future. 685 * 686 * XXXMAC: For the time being, use NOSUID to also prohibit 687 * transitions on the file system. 688 */ 689 credential_changing = 0; 690 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 691 attr.va_uid; 692 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 693 attr.va_gid; 694 #ifdef MAC 695 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 696 interpvplabel, imgp); 697 credential_changing |= will_transition; 698 #endif 699 700 if (credential_changing && 701 #ifdef CAPABILITY_MODE 702 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 703 #endif 704 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 705 (p->p_flag & P_TRACED) == 0) { 706 /* 707 * Turn off syscall tracing for set-id programs, except for 708 * root. Record any set-id flags first to make sure that 709 * we do not regain any tracing during a possible block. 710 */ 711 setsugid(p); 712 713 #ifdef KTRACE 714 if (p->p_tracecred != NULL && 715 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0)) 716 ktrprocexec(p, &tracecred, &tracevp); 717 #endif 718 /* 719 * Close any file descriptors 0..2 that reference procfs, 720 * then make sure file descriptors 0..2 are in use. 721 * 722 * setugidsafety() may call closef() and then pfind() 723 * which may grab the process lock. 724 * fdcheckstd() may call falloc() which may block to 725 * allocate memory, so temporarily drop the process lock. 726 */ 727 PROC_UNLOCK(p); 728 VOP_UNLOCK(imgp->vp, 0); 729 setugidsafety(td); 730 error = fdcheckstd(td); 731 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 732 if (error != 0) 733 goto done1; 734 PROC_LOCK(p); 735 /* 736 * Set the new credentials. 737 */ 738 if (attr.va_mode & S_ISUID) 739 change_euid(newcred, euip); 740 if (attr.va_mode & S_ISGID) 741 change_egid(newcred, attr.va_gid); 742 #ifdef MAC 743 if (will_transition) { 744 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 745 interpvplabel, imgp); 746 } 747 #endif 748 /* 749 * Implement correct POSIX saved-id behavior. 750 * 751 * XXXMAC: Note that the current logic will save the 752 * uid and gid if a MAC domain transition occurs, even 753 * though maybe it shouldn't. 754 */ 755 change_svuid(newcred, newcred->cr_uid); 756 change_svgid(newcred, newcred->cr_gid); 757 p->p_ucred = newcred; 758 newcred = NULL; 759 } else { 760 if (oldcred->cr_uid == oldcred->cr_ruid && 761 oldcred->cr_gid == oldcred->cr_rgid) 762 p->p_flag &= ~P_SUGID; 763 /* 764 * Implement correct POSIX saved-id behavior. 765 * 766 * XXX: It's not clear that the existing behavior is 767 * POSIX-compliant. A number of sources indicate that the 768 * saved uid/gid should only be updated if the new ruid is 769 * not equal to the old ruid, or the new euid is not equal 770 * to the old euid and the new euid is not equal to the old 771 * ruid. The FreeBSD code always updates the saved uid/gid. 772 * Also, this code uses the new (replaced) euid and egid as 773 * the source, which may or may not be the right ones to use. 774 */ 775 if (oldcred->cr_svuid != oldcred->cr_uid || 776 oldcred->cr_svgid != oldcred->cr_gid) { 777 change_svuid(newcred, newcred->cr_uid); 778 change_svgid(newcred, newcred->cr_gid); 779 p->p_ucred = newcred; 780 newcred = NULL; 781 } 782 } 783 784 /* 785 * Store the vp for use in procfs. This vnode was referenced prior 786 * to locking the proc lock. 787 */ 788 textvp = p->p_textvp; 789 p->p_textvp = binvp; 790 791 #ifdef KDTRACE_HOOKS 792 /* 793 * Tell the DTrace fasttrap provider about the exec if it 794 * has declared an interest. 795 */ 796 if (dtrace_fasttrap_exec) 797 dtrace_fasttrap_exec(p); 798 #endif 799 800 /* 801 * Notify others that we exec'd, and clear the P_INEXEC flag 802 * as we're now a bona fide freshly-execed process. 803 */ 804 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 805 p->p_flag &= ~P_INEXEC; 806 807 /* clear "fork but no exec" flag, as we _are_ execing */ 808 p->p_acflag &= ~AFORK; 809 810 /* 811 * Free any previous argument cache and replace it with 812 * the new argument cache, if any. 813 */ 814 oldargs = p->p_args; 815 p->p_args = newargs; 816 newargs = NULL; 817 818 #ifdef HWPMC_HOOKS 819 /* 820 * Check if system-wide sampling is in effect or if the 821 * current process is using PMCs. If so, do exec() time 822 * processing. This processing needs to happen AFTER the 823 * P_INEXEC flag is cleared. 824 * 825 * The proc lock needs to be released before taking the PMC 826 * SX. 827 */ 828 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 829 PROC_UNLOCK(p); 830 VOP_UNLOCK(imgp->vp, 0); 831 pe.pm_credentialschanged = credential_changing; 832 pe.pm_entryaddr = imgp->entry_addr; 833 834 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 835 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 836 } else 837 PROC_UNLOCK(p); 838 #else /* !HWPMC_HOOKS */ 839 PROC_UNLOCK(p); 840 #endif 841 842 /* Set values passed into the program in registers. */ 843 if (p->p_sysent->sv_setregs) 844 (*p->p_sysent->sv_setregs)(td, imgp, 845 (u_long)(uintptr_t)stack_base); 846 else 847 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 848 849 vfs_mark_atime(imgp->vp, td->td_ucred); 850 851 SDT_PROBE1(proc, kernel, , exec__success, args->fname); 852 853 done1: 854 /* 855 * Free any resources malloc'd earlier that we didn't use. 856 */ 857 uifree(euip); 858 if (newcred == NULL) 859 crfree(oldcred); 860 else 861 crfree(newcred); 862 VOP_UNLOCK(imgp->vp, 0); 863 864 /* 865 * Handle deferred decrement of ref counts. 866 */ 867 if (textvp != NULL) { 868 int tvfslocked; 869 870 tvfslocked = VFS_LOCK_GIANT(textvp->v_mount); 871 vrele(textvp); 872 VFS_UNLOCK_GIANT(tvfslocked); 873 } 874 if (binvp && error != 0) 875 vrele(binvp); 876 #ifdef KTRACE 877 if (tracevp != NULL) { 878 int tvfslocked; 879 880 tvfslocked = VFS_LOCK_GIANT(tracevp->v_mount); 881 vrele(tracevp); 882 VFS_UNLOCK_GIANT(tvfslocked); 883 } 884 if (tracecred != NULL) 885 crfree(tracecred); 886 #endif 887 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 888 pargs_drop(oldargs); 889 pargs_drop(newargs); 890 if (oldsigacts != NULL) 891 sigacts_free(oldsigacts); 892 893 exec_fail_dealloc: 894 895 /* 896 * free various allocated resources 897 */ 898 if (imgp->firstpage != NULL) 899 exec_unmap_first_page(imgp); 900 901 if (imgp->vp != NULL) { 902 if (args->fname) 903 NDFREE(&nd, NDF_ONLY_PNBUF); 904 if (imgp->opened) 905 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 906 vput(imgp->vp); 907 } 908 909 if (imgp->object != NULL) 910 vm_object_deallocate(imgp->object); 911 912 free(imgp->freepath, M_TEMP); 913 914 if (error == 0) { 915 PROC_LOCK(p); 916 td->td_dbgflags |= TDB_EXEC; 917 PROC_UNLOCK(p); 918 919 /* 920 * Stop the process here if its stop event mask has 921 * the S_EXEC bit set. 922 */ 923 STOPEVENT(p, S_EXEC, 0); 924 goto done2; 925 } 926 927 exec_fail: 928 /* we're done here, clear P_INEXEC */ 929 PROC_LOCK(p); 930 p->p_flag &= ~P_INEXEC; 931 PROC_UNLOCK(p); 932 933 SDT_PROBE1(proc, kernel, , exec__failure, error); 934 935 done2: 936 #ifdef MAC 937 mac_execve_exit(imgp); 938 mac_execve_interpreter_exit(interpvplabel); 939 #endif 940 VFS_UNLOCK_GIANT(vfslocked); 941 exec_free_args(args); 942 943 if (error && imgp->vmspace_destroyed) { 944 /* sorry, no more process anymore. exit gracefully */ 945 exit1(td, W_EXITCODE(0, SIGABRT)); 946 /* NOT REACHED */ 947 } 948 949 #ifdef KTRACE 950 if (error == 0) 951 ktrprocctor(p); 952 #endif 953 954 return (error); 955 } 956 957 int 958 exec_map_first_page(imgp) 959 struct image_params *imgp; 960 { 961 int rv, i; 962 int initial_pagein; 963 vm_page_t ma[VM_INITIAL_PAGEIN]; 964 vm_object_t object; 965 966 if (imgp->firstpage != NULL) 967 exec_unmap_first_page(imgp); 968 969 object = imgp->vp->v_object; 970 if (object == NULL) 971 return (EACCES); 972 VM_OBJECT_LOCK(object); 973 #if VM_NRESERVLEVEL > 0 974 if ((object->flags & OBJ_COLORED) == 0) { 975 object->flags |= OBJ_COLORED; 976 object->pg_color = 0; 977 } 978 #endif 979 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 980 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 981 initial_pagein = VM_INITIAL_PAGEIN; 982 if (initial_pagein > object->size) 983 initial_pagein = object->size; 984 for (i = 1; i < initial_pagein; i++) { 985 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 986 if (ma[i]->valid) 987 break; 988 if ((ma[i]->oflags & VPO_BUSY) || ma[i]->busy) 989 break; 990 vm_page_busy(ma[i]); 991 } else { 992 ma[i] = vm_page_alloc(object, i, 993 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 994 if (ma[i] == NULL) 995 break; 996 } 997 } 998 initial_pagein = i; 999 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 1000 ma[0] = vm_page_lookup(object, 0); 1001 if ((rv != VM_PAGER_OK) || (ma[0] == NULL)) { 1002 if (ma[0] != NULL) { 1003 vm_page_lock(ma[0]); 1004 vm_page_free(ma[0]); 1005 vm_page_unlock(ma[0]); 1006 } 1007 VM_OBJECT_UNLOCK(object); 1008 return (EIO); 1009 } 1010 } 1011 vm_page_lock(ma[0]); 1012 vm_page_hold(ma[0]); 1013 vm_page_unlock(ma[0]); 1014 vm_page_wakeup(ma[0]); 1015 VM_OBJECT_UNLOCK(object); 1016 1017 imgp->firstpage = sf_buf_alloc(ma[0], 0); 1018 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 1019 1020 return (0); 1021 } 1022 1023 void 1024 exec_unmap_first_page(imgp) 1025 struct image_params *imgp; 1026 { 1027 vm_page_t m; 1028 1029 if (imgp->firstpage != NULL) { 1030 m = sf_buf_page(imgp->firstpage); 1031 sf_buf_free(imgp->firstpage); 1032 imgp->firstpage = NULL; 1033 vm_page_lock(m); 1034 vm_page_unhold(m); 1035 vm_page_unlock(m); 1036 } 1037 } 1038 1039 /* 1040 * Destroy old address space, and allocate a new stack 1041 * The new stack is only SGROWSIZ large because it is grown 1042 * automatically in trap.c. 1043 */ 1044 int 1045 exec_new_vmspace(imgp, sv) 1046 struct image_params *imgp; 1047 struct sysentvec *sv; 1048 { 1049 int error; 1050 struct proc *p = imgp->proc; 1051 struct vmspace *vmspace = p->p_vmspace; 1052 vm_object_t obj; 1053 vm_offset_t sv_minuser, stack_addr; 1054 vm_map_t map; 1055 u_long ssiz; 1056 1057 imgp->vmspace_destroyed = 1; 1058 imgp->sysent = sv; 1059 1060 /* May be called with Giant held */ 1061 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1062 1063 /* 1064 * Blow away entire process VM, if address space not shared, 1065 * otherwise, create a new VM space so that other threads are 1066 * not disrupted 1067 */ 1068 map = &vmspace->vm_map; 1069 if (map_at_zero) 1070 sv_minuser = sv->sv_minuser; 1071 else 1072 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1073 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1074 vm_map_max(map) == sv->sv_maxuser) { 1075 shmexit(vmspace); 1076 pmap_remove_pages(vmspace_pmap(vmspace)); 1077 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1078 } else { 1079 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1080 if (error) 1081 return (error); 1082 vmspace = p->p_vmspace; 1083 map = &vmspace->vm_map; 1084 } 1085 1086 /* Map a shared page */ 1087 obj = sv->sv_shared_page_obj; 1088 if (obj != NULL) { 1089 vm_object_reference(obj); 1090 error = vm_map_fixed(map, obj, 0, 1091 sv->sv_shared_page_base, sv->sv_shared_page_len, 1092 VM_PROT_READ | VM_PROT_EXECUTE, 1093 VM_PROT_READ | VM_PROT_EXECUTE, 1094 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1095 if (error) { 1096 vm_object_deallocate(obj); 1097 return (error); 1098 } 1099 } 1100 1101 /* Allocate a new stack */ 1102 if (sv->sv_maxssiz != NULL) 1103 ssiz = *sv->sv_maxssiz; 1104 else 1105 ssiz = maxssiz; 1106 stack_addr = sv->sv_usrstack - ssiz; 1107 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1108 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1109 sv->sv_stackprot, 1110 VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1111 if (error) 1112 return (error); 1113 1114 #ifdef __ia64__ 1115 /* Allocate a new register stack */ 1116 stack_addr = IA64_BACKINGSTORE; 1117 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1118 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP); 1119 if (error) 1120 return (error); 1121 #endif 1122 1123 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 1124 * VM_STACK case, but they are still used to monitor the size of the 1125 * process stack so we can check the stack rlimit. 1126 */ 1127 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1128 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1129 1130 return (0); 1131 } 1132 1133 /* 1134 * Copy out argument and environment strings from the old process address 1135 * space into the temporary string buffer. 1136 */ 1137 int 1138 exec_copyin_args(struct image_args *args, char *fname, 1139 enum uio_seg segflg, char **argv, char **envv) 1140 { 1141 char *argp, *envp; 1142 int error; 1143 size_t length; 1144 1145 bzero(args, sizeof(*args)); 1146 if (argv == NULL) 1147 return (EFAULT); 1148 1149 /* 1150 * Allocate demand-paged memory for the file name, argument, and 1151 * environment strings. 1152 */ 1153 error = exec_alloc_args(args); 1154 if (error != 0) 1155 return (error); 1156 1157 /* 1158 * Copy the file name. 1159 */ 1160 if (fname != NULL) { 1161 args->fname = args->buf; 1162 error = (segflg == UIO_SYSSPACE) ? 1163 copystr(fname, args->fname, PATH_MAX, &length) : 1164 copyinstr(fname, args->fname, PATH_MAX, &length); 1165 if (error != 0) 1166 goto err_exit; 1167 } else 1168 length = 0; 1169 1170 args->begin_argv = args->buf + length; 1171 args->endp = args->begin_argv; 1172 args->stringspace = ARG_MAX; 1173 1174 /* 1175 * extract arguments first 1176 */ 1177 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 1178 if (argp == (caddr_t) -1) { 1179 error = EFAULT; 1180 goto err_exit; 1181 } 1182 if ((error = copyinstr(argp, args->endp, 1183 args->stringspace, &length))) { 1184 if (error == ENAMETOOLONG) 1185 error = E2BIG; 1186 goto err_exit; 1187 } 1188 args->stringspace -= length; 1189 args->endp += length; 1190 args->argc++; 1191 } 1192 1193 args->begin_envv = args->endp; 1194 1195 /* 1196 * extract environment strings 1197 */ 1198 if (envv) { 1199 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) { 1200 if (envp == (caddr_t)-1) { 1201 error = EFAULT; 1202 goto err_exit; 1203 } 1204 if ((error = copyinstr(envp, args->endp, 1205 args->stringspace, &length))) { 1206 if (error == ENAMETOOLONG) 1207 error = E2BIG; 1208 goto err_exit; 1209 } 1210 args->stringspace -= length; 1211 args->endp += length; 1212 args->envc++; 1213 } 1214 } 1215 1216 return (0); 1217 1218 err_exit: 1219 exec_free_args(args); 1220 return (error); 1221 } 1222 1223 /* 1224 * Allocate temporary demand-paged, zero-filled memory for the file name, 1225 * argument, and environment strings. Returns zero if the allocation succeeds 1226 * and ENOMEM otherwise. 1227 */ 1228 int 1229 exec_alloc_args(struct image_args *args) 1230 { 1231 1232 args->buf = (char *)kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 1233 return (args->buf != NULL ? 0 : ENOMEM); 1234 } 1235 1236 void 1237 exec_free_args(struct image_args *args) 1238 { 1239 1240 if (args->buf != NULL) { 1241 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf, 1242 PATH_MAX + ARG_MAX); 1243 args->buf = NULL; 1244 } 1245 if (args->fname_buf != NULL) { 1246 free(args->fname_buf, M_TEMP); 1247 args->fname_buf = NULL; 1248 } 1249 } 1250 1251 /* 1252 * Copy strings out to the new process address space, constructing new arg 1253 * and env vector tables. Return a pointer to the base so that it can be used 1254 * as the initial stack pointer. 1255 */ 1256 register_t * 1257 exec_copyout_strings(imgp) 1258 struct image_params *imgp; 1259 { 1260 int argc, envc; 1261 char **vectp; 1262 char *stringp; 1263 uintptr_t destp; 1264 register_t *stack_base; 1265 struct ps_strings *arginfo; 1266 struct proc *p; 1267 size_t execpath_len; 1268 int szsigcode, szps; 1269 char canary[sizeof(long) * 8]; 1270 1271 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1272 /* 1273 * Calculate string base and vector table pointers. 1274 * Also deal with signal trampoline code for this exec type. 1275 */ 1276 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1277 execpath_len = strlen(imgp->execpath) + 1; 1278 else 1279 execpath_len = 0; 1280 p = imgp->proc; 1281 szsigcode = 0; 1282 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1283 if (p->p_sysent->sv_sigcode_base == 0) { 1284 if (p->p_sysent->sv_szsigcode != NULL) 1285 szsigcode = *(p->p_sysent->sv_szsigcode); 1286 } 1287 destp = (uintptr_t)arginfo; 1288 1289 /* 1290 * install sigcode 1291 */ 1292 if (szsigcode != 0) { 1293 destp -= szsigcode; 1294 destp = rounddown2(destp, sizeof(void *)); 1295 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode); 1296 } 1297 1298 /* 1299 * Copy the image path for the rtld. 1300 */ 1301 if (execpath_len != 0) { 1302 destp -= execpath_len; 1303 imgp->execpathp = destp; 1304 copyout(imgp->execpath, (void *)destp, execpath_len); 1305 } 1306 1307 /* 1308 * Prepare the canary for SSP. 1309 */ 1310 arc4rand(canary, sizeof(canary), 0); 1311 destp -= sizeof(canary); 1312 imgp->canary = destp; 1313 copyout(canary, (void *)destp, sizeof(canary)); 1314 imgp->canarylen = sizeof(canary); 1315 1316 /* 1317 * Prepare the pagesizes array. 1318 */ 1319 destp -= szps; 1320 destp = rounddown2(destp, sizeof(void *)); 1321 imgp->pagesizes = destp; 1322 copyout(pagesizes, (void *)destp, szps); 1323 imgp->pagesizeslen = szps; 1324 1325 destp -= ARG_MAX - imgp->args->stringspace; 1326 destp = rounddown2(destp, sizeof(void *)); 1327 1328 /* 1329 * If we have a valid auxargs ptr, prepare some room 1330 * on the stack. 1331 */ 1332 if (imgp->auxargs) { 1333 /* 1334 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1335 * lower compatibility. 1336 */ 1337 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1338 (AT_COUNT * 2); 1339 /* 1340 * The '+ 2' is for the null pointers at the end of each of 1341 * the arg and env vector sets,and imgp->auxarg_size is room 1342 * for argument of Runtime loader. 1343 */ 1344 vectp = (char **)(destp - (imgp->args->argc + 1345 imgp->args->envc + 2 + imgp->auxarg_size) 1346 * sizeof(char *)); 1347 } else { 1348 /* 1349 * The '+ 2' is for the null pointers at the end of each of 1350 * the arg and env vector sets 1351 */ 1352 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc 1353 + 2) * sizeof(char *)); 1354 } 1355 1356 /* 1357 * vectp also becomes our initial stack base 1358 */ 1359 stack_base = (register_t *)vectp; 1360 1361 stringp = imgp->args->begin_argv; 1362 argc = imgp->args->argc; 1363 envc = imgp->args->envc; 1364 1365 /* 1366 * Copy out strings - arguments and environment. 1367 */ 1368 copyout(stringp, (void *)destp, ARG_MAX - imgp->args->stringspace); 1369 1370 /* 1371 * Fill in "ps_strings" struct for ps, w, etc. 1372 */ 1373 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1374 suword32(&arginfo->ps_nargvstr, argc); 1375 1376 /* 1377 * Fill in argument portion of vector table. 1378 */ 1379 for (; argc > 0; --argc) { 1380 suword(vectp++, (long)(intptr_t)destp); 1381 while (*stringp++ != 0) 1382 destp++; 1383 destp++; 1384 } 1385 1386 /* a null vector table pointer separates the argp's from the envp's */ 1387 suword(vectp++, 0); 1388 1389 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1390 suword32(&arginfo->ps_nenvstr, envc); 1391 1392 /* 1393 * Fill in environment portion of vector table. 1394 */ 1395 for (; envc > 0; --envc) { 1396 suword(vectp++, (long)(intptr_t)destp); 1397 while (*stringp++ != 0) 1398 destp++; 1399 destp++; 1400 } 1401 1402 /* end of vector table is a null pointer */ 1403 suword(vectp, 0); 1404 1405 return (stack_base); 1406 } 1407 1408 /* 1409 * Check permissions of file to execute. 1410 * Called with imgp->vp locked. 1411 * Return 0 for success or error code on failure. 1412 */ 1413 int 1414 exec_check_permissions(imgp) 1415 struct image_params *imgp; 1416 { 1417 struct vnode *vp = imgp->vp; 1418 struct vattr *attr = imgp->attr; 1419 struct thread *td; 1420 int error, writecount; 1421 1422 td = curthread; 1423 1424 /* Get file attributes */ 1425 error = VOP_GETATTR(vp, attr, td->td_ucred); 1426 if (error) 1427 return (error); 1428 1429 #ifdef MAC 1430 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1431 if (error) 1432 return (error); 1433 #endif 1434 1435 /* 1436 * 1) Check if file execution is disabled for the filesystem that 1437 * this file resides on. 1438 * 2) Ensure that at least one execute bit is on. Otherwise, a 1439 * privileged user will always succeed, and we don't want this 1440 * to happen unless the file really is executable. 1441 * 3) Ensure that the file is a regular file. 1442 */ 1443 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1444 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1445 (attr->va_type != VREG)) 1446 return (EACCES); 1447 1448 /* 1449 * Zero length files can't be exec'd 1450 */ 1451 if (attr->va_size == 0) 1452 return (ENOEXEC); 1453 1454 /* 1455 * Check for execute permission to file based on current credentials. 1456 */ 1457 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1458 if (error) 1459 return (error); 1460 1461 /* 1462 * Check number of open-for-writes on the file and deny execution 1463 * if there are any. 1464 */ 1465 error = VOP_GET_WRITECOUNT(vp, &writecount); 1466 if (error != 0) 1467 return (error); 1468 if (writecount != 0) 1469 return (ETXTBSY); 1470 1471 /* 1472 * Call filesystem specific open routine (which does nothing in the 1473 * general case). 1474 */ 1475 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1476 if (error == 0) 1477 imgp->opened = 1; 1478 return (error); 1479 } 1480 1481 /* 1482 * Exec handler registration 1483 */ 1484 int 1485 exec_register(execsw_arg) 1486 const struct execsw *execsw_arg; 1487 { 1488 const struct execsw **es, **xs, **newexecsw; 1489 int count = 2; /* New slot and trailing NULL */ 1490 1491 if (execsw) 1492 for (es = execsw; *es; es++) 1493 count++; 1494 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1495 if (newexecsw == NULL) 1496 return (ENOMEM); 1497 xs = newexecsw; 1498 if (execsw) 1499 for (es = execsw; *es; es++) 1500 *xs++ = *es; 1501 *xs++ = execsw_arg; 1502 *xs = NULL; 1503 if (execsw) 1504 free(execsw, M_TEMP); 1505 execsw = newexecsw; 1506 return (0); 1507 } 1508 1509 int 1510 exec_unregister(execsw_arg) 1511 const struct execsw *execsw_arg; 1512 { 1513 const struct execsw **es, **xs, **newexecsw; 1514 int count = 1; 1515 1516 if (execsw == NULL) 1517 panic("unregister with no handlers left?\n"); 1518 1519 for (es = execsw; *es; es++) { 1520 if (*es == execsw_arg) 1521 break; 1522 } 1523 if (*es == NULL) 1524 return (ENOENT); 1525 for (es = execsw; *es; es++) 1526 if (*es != execsw_arg) 1527 count++; 1528 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1529 if (newexecsw == NULL) 1530 return (ENOMEM); 1531 xs = newexecsw; 1532 for (es = execsw; *es; es++) 1533 if (*es != execsw_arg) 1534 *xs++ = *es; 1535 *xs = NULL; 1536 if (execsw) 1537 free(execsw, M_TEMP); 1538 execsw = newexecsw; 1539 return (0); 1540 }
Cache object: 26837f061e1f722a6919c9441f6497f7
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