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: releng/9.1/sys/kern/kern_exec.c 267018 2014-06-03 19:03:11Z delphij $"); 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_DEFINE(proc, kernel, , exec, exec); 99 SDT_PROBE_ARGTYPE(proc, kernel, , exec, 0, "char *"); 100 SDT_PROBE_DEFINE(proc, kernel, , exec_failure, exec-failure); 101 SDT_PROBE_ARGTYPE(proc, kernel, , exec_failure, 0, "int"); 102 SDT_PROBE_DEFINE(proc, kernel, , exec_success, exec-success); 103 SDT_PROBE_ARGTYPE(proc, kernel, , exec_success, 0, "char *"); 104 105 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 106 107 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 108 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 109 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 110 static int do_execve(struct thread *td, struct image_args *args, 111 struct mac *mac_p); 112 113 /* XXX This should be vm_size_t. */ 114 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD, 115 NULL, 0, sysctl_kern_ps_strings, "LU", ""); 116 117 /* XXX This should be vm_size_t. */ 118 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 119 CTLFLAG_CAPRD, NULL, 0, sysctl_kern_usrstack, "LU", ""); 120 121 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 122 NULL, 0, sysctl_kern_stackprot, "I", ""); 123 124 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 125 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 126 &ps_arg_cache_limit, 0, ""); 127 128 static int map_at_zero = 0; 129 TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero); 130 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &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(td, uap) 197 struct thread *td; 198 struct execve_args /* { 199 char *fname; 200 char **argv; 201 char **envv; 202 } */ *uap; 203 { 204 int error; 205 struct image_args args; 206 207 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 208 uap->argv, uap->envv); 209 if (error == 0) 210 error = kern_execve(td, &args, NULL); 211 return (error); 212 } 213 214 #ifndef _SYS_SYSPROTO_H_ 215 struct fexecve_args { 216 int fd; 217 char **argv; 218 char **envv; 219 } 220 #endif 221 int 222 sys_fexecve(struct thread *td, struct fexecve_args *uap) 223 { 224 int error; 225 struct image_args args; 226 227 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 228 uap->argv, uap->envv); 229 if (error == 0) { 230 args.fd = uap->fd; 231 error = kern_execve(td, &args, NULL); 232 } 233 return (error); 234 } 235 236 #ifndef _SYS_SYSPROTO_H_ 237 struct __mac_execve_args { 238 char *fname; 239 char **argv; 240 char **envv; 241 struct mac *mac_p; 242 }; 243 #endif 244 245 int 246 sys___mac_execve(td, uap) 247 struct thread *td; 248 struct __mac_execve_args /* { 249 char *fname; 250 char **argv; 251 char **envv; 252 struct mac *mac_p; 253 } */ *uap; 254 { 255 #ifdef MAC 256 int error; 257 struct image_args args; 258 259 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 260 uap->argv, uap->envv); 261 if (error == 0) 262 error = kern_execve(td, &args, uap->mac_p); 263 return (error); 264 #else 265 return (ENOSYS); 266 #endif 267 } 268 269 /* 270 * XXX: kern_execve has the astonishing property of not always returning to 271 * the caller. If sufficiently bad things happen during the call to 272 * do_execve(), it can end up calling exit1(); as a result, callers must 273 * avoid doing anything which they might need to undo (e.g., allocating 274 * memory). 275 */ 276 int 277 kern_execve(td, args, mac_p) 278 struct thread *td; 279 struct image_args *args; 280 struct mac *mac_p; 281 { 282 struct proc *p = td->td_proc; 283 struct vmspace *oldvmspace; 284 int error; 285 286 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 287 args->begin_envv - args->begin_argv); 288 AUDIT_ARG_ENVV(args->begin_envv, args->envc, 289 args->endp - args->begin_envv); 290 if (p->p_flag & P_HADTHREADS) { 291 PROC_LOCK(p); 292 if (thread_single(SINGLE_BOUNDARY)) { 293 PROC_UNLOCK(p); 294 exec_free_args(args); 295 return (ERESTART); /* Try again later. */ 296 } 297 PROC_UNLOCK(p); 298 } 299 300 KASSERT((td->td_pflags & TDP_EXECVMSPC) == 0, ("nested execve")); 301 oldvmspace = td->td_proc->p_vmspace; 302 error = do_execve(td, args, mac_p); 303 304 if (p->p_flag & P_HADTHREADS) { 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(SINGLE_EXIT); 312 else 313 thread_single_end(); 314 PROC_UNLOCK(p); 315 } 316 if ((td->td_pflags & TDP_EXECVMSPC) != 0) { 317 KASSERT(td->td_proc->p_vmspace != oldvmspace, 318 ("oldvmspace still used")); 319 vmspace_free(oldvmspace); 320 td->td_pflags &= ~TDP_EXECVMSPC; 321 } 322 323 return (error); 324 } 325 326 /* 327 * In-kernel implementation of execve(). All arguments are assumed to be 328 * userspace pointers from the passed thread. 329 */ 330 static int 331 do_execve(td, args, mac_p) 332 struct thread *td; 333 struct image_args *args; 334 struct mac *mac_p; 335 { 336 struct proc *p = td->td_proc; 337 struct nameidata nd; 338 struct ucred *newcred = NULL, *oldcred; 339 struct uidinfo *euip; 340 register_t *stack_base; 341 int error, i; 342 struct image_params image_params, *imgp; 343 struct vattr attr; 344 int (*img_first)(struct image_params *); 345 struct pargs *oldargs = NULL, *newargs = NULL; 346 struct sigacts *oldsigacts, *newsigacts; 347 #ifdef KTRACE 348 struct vnode *tracevp = NULL; 349 struct ucred *tracecred = NULL; 350 #endif 351 struct vnode *textvp = NULL, *binvp = NULL; 352 int credential_changing; 353 int vfslocked; 354 int textset; 355 #ifdef MAC 356 struct label *interpvplabel = NULL; 357 int will_transition; 358 #endif 359 #ifdef HWPMC_HOOKS 360 struct pmckern_procexec pe; 361 #endif 362 static const char fexecv_proc_title[] = "(fexecv)"; 363 364 vfslocked = 0; 365 imgp = &image_params; 366 367 /* 368 * Lock the process and set the P_INEXEC flag to indicate that 369 * it should be left alone until we're done here. This is 370 * necessary to avoid race conditions - e.g. in ptrace() - 371 * that might allow a local user to illicitly obtain elevated 372 * privileges. 373 */ 374 PROC_LOCK(p); 375 KASSERT((p->p_flag & P_INEXEC) == 0, 376 ("%s(): process already has P_INEXEC flag", __func__)); 377 p->p_flag |= P_INEXEC; 378 PROC_UNLOCK(p); 379 380 /* 381 * Initialize part of the common data 382 */ 383 imgp->proc = p; 384 imgp->execlabel = NULL; 385 imgp->attr = &attr; 386 imgp->entry_addr = 0; 387 imgp->reloc_base = 0; 388 imgp->vmspace_destroyed = 0; 389 imgp->interpreted = 0; 390 imgp->opened = 0; 391 imgp->interpreter_name = NULL; 392 imgp->auxargs = NULL; 393 imgp->vp = NULL; 394 imgp->object = NULL; 395 imgp->firstpage = NULL; 396 imgp->ps_strings = 0; 397 imgp->auxarg_size = 0; 398 imgp->args = args; 399 imgp->execpath = imgp->freepath = NULL; 400 imgp->execpathp = 0; 401 imgp->canary = 0; 402 imgp->canarylen = 0; 403 imgp->pagesizes = 0; 404 imgp->pagesizeslen = 0; 405 imgp->stack_prot = 0; 406 407 #ifdef MAC 408 error = mac_execve_enter(imgp, mac_p); 409 if (error) 410 goto exec_fail; 411 #endif 412 413 imgp->image_header = NULL; 414 415 /* 416 * Translate the file name. namei() returns a vnode pointer 417 * in ni_vp amoung other things. 418 * 419 * XXXAUDIT: It would be desirable to also audit the name of the 420 * interpreter if this is an interpreted binary. 421 */ 422 if (args->fname != NULL) { 423 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 424 | MPSAFE | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 425 } 426 427 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 428 429 interpret: 430 if (args->fname != NULL) { 431 #ifdef CAPABILITY_MODE 432 /* 433 * While capability mode can't reach this point via direct 434 * path arguments to execve(), we also don't allow 435 * interpreters to be used in capability mode (for now). 436 * Catch indirect lookups and return a permissions error. 437 */ 438 if (IN_CAPABILITY_MODE(td)) { 439 error = ECAPMODE; 440 goto exec_fail; 441 } 442 #endif 443 error = namei(&nd); 444 if (error) 445 goto exec_fail; 446 447 vfslocked = NDHASGIANT(&nd); 448 binvp = nd.ni_vp; 449 imgp->vp = binvp; 450 } else { 451 AUDIT_ARG_FD(args->fd); 452 /* 453 * Some might argue that CAP_READ and/or CAP_MMAP should also 454 * be required here; such arguments will be entertained. 455 * 456 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 457 */ 458 error = fgetvp_exec(td, args->fd, CAP_FEXECVE, &binvp); 459 if (error) 460 goto exec_fail; 461 vfslocked = VFS_LOCK_GIANT(binvp->v_mount); 462 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY); 463 AUDIT_ARG_VNODE1(binvp); 464 imgp->vp = binvp; 465 } 466 467 /* 468 * Check file permissions (also 'opens' file) 469 */ 470 error = exec_check_permissions(imgp); 471 if (error) 472 goto exec_fail_dealloc; 473 474 imgp->object = imgp->vp->v_object; 475 if (imgp->object != NULL) 476 vm_object_reference(imgp->object); 477 478 /* 479 * Set VV_TEXT now so no one can write to the executable while we're 480 * activating it. 481 * 482 * Remember if this was set before and unset it in case this is not 483 * actually an executable image. 484 */ 485 textset = imgp->vp->v_vflag & VV_TEXT; 486 ASSERT_VOP_ELOCKED(imgp->vp, "vv_text"); 487 imgp->vp->v_vflag |= VV_TEXT; 488 489 error = exec_map_first_page(imgp); 490 if (error) 491 goto exec_fail_dealloc; 492 493 imgp->proc->p_osrel = 0; 494 /* 495 * If the current process has a special image activator it 496 * wants to try first, call it. For example, emulating shell 497 * scripts differently. 498 */ 499 error = -1; 500 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 501 error = img_first(imgp); 502 503 /* 504 * Loop through the list of image activators, calling each one. 505 * An activator returns -1 if there is no match, 0 on success, 506 * and an error otherwise. 507 */ 508 for (i = 0; error == -1 && execsw[i]; ++i) { 509 if (execsw[i]->ex_imgact == NULL || 510 execsw[i]->ex_imgact == img_first) { 511 continue; 512 } 513 error = (*execsw[i]->ex_imgact)(imgp); 514 } 515 516 if (error) { 517 if (error == -1) { 518 if (textset == 0) { 519 ASSERT_VOP_ELOCKED(imgp->vp, "vv_text"); 520 imgp->vp->v_vflag &= ~VV_TEXT; 521 } 522 error = ENOEXEC; 523 } 524 goto exec_fail_dealloc; 525 } 526 527 /* 528 * Special interpreter operation, cleanup and loop up to try to 529 * activate the interpreter. 530 */ 531 if (imgp->interpreted) { 532 exec_unmap_first_page(imgp); 533 /* 534 * VV_TEXT needs to be unset for scripts. There is a short 535 * period before we determine that something is a script where 536 * VV_TEXT will be set. The vnode lock is held over this 537 * entire period so nothing should illegitimately be blocked. 538 */ 539 imgp->vp->v_vflag &= ~VV_TEXT; 540 /* free name buffer and old vnode */ 541 if (args->fname != NULL) 542 NDFREE(&nd, NDF_ONLY_PNBUF); 543 #ifdef MAC 544 mac_execve_interpreter_enter(binvp, &interpvplabel); 545 #endif 546 if (imgp->opened) { 547 VOP_CLOSE(binvp, FREAD, td->td_ucred, td); 548 imgp->opened = 0; 549 } 550 vput(binvp); 551 vm_object_deallocate(imgp->object); 552 imgp->object = NULL; 553 VFS_UNLOCK_GIANT(vfslocked); 554 vfslocked = 0; 555 /* set new name to that of the interpreter */ 556 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME | MPSAFE, 557 UIO_SYSSPACE, imgp->interpreter_name, td); 558 args->fname = imgp->interpreter_name; 559 goto interpret; 560 } 561 562 /* 563 * NB: We unlock the vnode here because it is believed that none 564 * of the sv_copyout_strings/sv_fixup operations require the vnode. 565 */ 566 VOP_UNLOCK(imgp->vp, 0); 567 568 /* 569 * Do the best to calculate the full path to the image file. 570 */ 571 if (imgp->auxargs != NULL && 572 ((args->fname != NULL && args->fname[0] == '/') || 573 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0)) 574 imgp->execpath = args->fname; 575 576 /* 577 * Copy out strings (args and env) and initialize stack base 578 */ 579 if (p->p_sysent->sv_copyout_strings) 580 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 581 else 582 stack_base = exec_copyout_strings(imgp); 583 584 /* 585 * If custom stack fixup routine present for this process 586 * let it do the stack setup. 587 * Else stuff argument count as first item on stack 588 */ 589 if (p->p_sysent->sv_fixup != NULL) 590 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 591 else 592 suword(--stack_base, imgp->args->argc); 593 594 /* 595 * For security and other reasons, the file descriptor table cannot 596 * be shared after an exec. 597 */ 598 fdunshare(p, td); 599 600 /* 601 * Malloc things before we need locks. 602 */ 603 newcred = crget(); 604 euip = uifind(attr.va_uid); 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 /* close files on exec */ 613 fdcloseexec(td); 614 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 615 616 /* Get a reference to the vnode prior to locking the proc */ 617 VREF(binvp); 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 PROC_LOCK(p); 626 oldcred = crcopysafe(p, newcred); 627 if (sigacts_shared(p->p_sigacts)) { 628 oldsigacts = p->p_sigacts; 629 PROC_UNLOCK(p); 630 newsigacts = sigacts_alloc(); 631 sigacts_copy(newsigacts, oldsigacts); 632 PROC_LOCK(p); 633 p->p_sigacts = newsigacts; 634 } else 635 oldsigacts = NULL; 636 637 /* Stop profiling */ 638 stopprofclock(p); 639 640 /* reset caught signals */ 641 execsigs(p); 642 643 /* name this process - nameiexec(p, ndp) */ 644 bzero(p->p_comm, sizeof(p->p_comm)); 645 if (args->fname) 646 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 647 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 648 else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0) 649 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 650 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 651 #ifdef KTR 652 sched_clear_tdname(td); 653 #endif 654 655 /* 656 * mark as execed, wakeup the process that vforked (if any) and tell 657 * it that it now has its own resources back 658 */ 659 p->p_flag |= P_EXEC; 660 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 661 p->p_flag &= ~P_PPWAIT; 662 cv_broadcast(&p->p_pwait); 663 } 664 665 /* 666 * Implement image setuid/setgid. 667 * 668 * Don't honor setuid/setgid if the filesystem prohibits it or if 669 * the process is being traced. 670 * 671 * We disable setuid/setgid/etc in compatibility mode on the basis 672 * that most setugid applications are not written with that 673 * environment in mind, and will therefore almost certainly operate 674 * incorrectly. In principle there's no reason that setugid 675 * applications might not be useful in capability mode, so we may want 676 * to reconsider this conservative design choice in the future. 677 * 678 * XXXMAC: For the time being, use NOSUID to also prohibit 679 * transitions on the file system. 680 */ 681 credential_changing = 0; 682 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 683 attr.va_uid; 684 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 685 attr.va_gid; 686 #ifdef MAC 687 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 688 interpvplabel, imgp); 689 credential_changing |= will_transition; 690 #endif 691 692 if (credential_changing && 693 #ifdef CAPABILITY_MODE 694 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 695 #endif 696 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 697 (p->p_flag & P_TRACED) == 0) { 698 /* 699 * Turn off syscall tracing for set-id programs, except for 700 * root. Record any set-id flags first to make sure that 701 * we do not regain any tracing during a possible block. 702 */ 703 setsugid(p); 704 705 #ifdef KTRACE 706 if (priv_check_cred(oldcred, PRIV_DEBUG_DIFFCRED, 0)) 707 ktrprocexec(p, &tracecred, &tracevp); 708 #endif 709 /* 710 * Close any file descriptors 0..2 that reference procfs, 711 * then make sure file descriptors 0..2 are in use. 712 * 713 * setugidsafety() may call closef() and then pfind() 714 * which may grab the process lock. 715 * fdcheckstd() may call falloc() which may block to 716 * allocate memory, so temporarily drop the process lock. 717 */ 718 PROC_UNLOCK(p); 719 VOP_UNLOCK(imgp->vp, 0); 720 setugidsafety(td); 721 error = fdcheckstd(td); 722 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 723 if (error != 0) 724 goto done1; 725 PROC_LOCK(p); 726 /* 727 * Set the new credentials. 728 */ 729 if (attr.va_mode & S_ISUID) 730 change_euid(newcred, euip); 731 if (attr.va_mode & S_ISGID) 732 change_egid(newcred, attr.va_gid); 733 #ifdef MAC 734 if (will_transition) { 735 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 736 interpvplabel, imgp); 737 } 738 #endif 739 /* 740 * Implement correct POSIX saved-id behavior. 741 * 742 * XXXMAC: Note that the current logic will save the 743 * uid and gid if a MAC domain transition occurs, even 744 * though maybe it shouldn't. 745 */ 746 change_svuid(newcred, newcred->cr_uid); 747 change_svgid(newcred, newcred->cr_gid); 748 p->p_ucred = newcred; 749 newcred = NULL; 750 } else { 751 if (oldcred->cr_uid == oldcred->cr_ruid && 752 oldcred->cr_gid == oldcred->cr_rgid) 753 p->p_flag &= ~P_SUGID; 754 /* 755 * Implement correct POSIX saved-id behavior. 756 * 757 * XXX: It's not clear that the existing behavior is 758 * POSIX-compliant. A number of sources indicate that the 759 * saved uid/gid should only be updated if the new ruid is 760 * not equal to the old ruid, or the new euid is not equal 761 * to the old euid and the new euid is not equal to the old 762 * ruid. The FreeBSD code always updates the saved uid/gid. 763 * Also, this code uses the new (replaced) euid and egid as 764 * the source, which may or may not be the right ones to use. 765 */ 766 if (oldcred->cr_svuid != oldcred->cr_uid || 767 oldcred->cr_svgid != oldcred->cr_gid) { 768 change_svuid(newcred, newcred->cr_uid); 769 change_svgid(newcred, newcred->cr_gid); 770 p->p_ucred = newcred; 771 newcred = NULL; 772 } 773 } 774 775 /* 776 * Store the vp for use in procfs. This vnode was referenced prior 777 * to locking the proc lock. 778 */ 779 textvp = p->p_textvp; 780 p->p_textvp = binvp; 781 782 #ifdef KDTRACE_HOOKS 783 /* 784 * Tell the DTrace fasttrap provider about the exec if it 785 * has declared an interest. 786 */ 787 if (dtrace_fasttrap_exec) 788 dtrace_fasttrap_exec(p); 789 #endif 790 791 /* 792 * Notify others that we exec'd, and clear the P_INEXEC flag 793 * as we're now a bona fide freshly-execed process. 794 */ 795 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 796 p->p_flag &= ~P_INEXEC; 797 798 /* clear "fork but no exec" flag, as we _are_ execing */ 799 p->p_acflag &= ~AFORK; 800 801 /* 802 * Free any previous argument cache and replace it with 803 * the new argument cache, if any. 804 */ 805 oldargs = p->p_args; 806 p->p_args = newargs; 807 newargs = NULL; 808 809 #ifdef HWPMC_HOOKS 810 /* 811 * Check if system-wide sampling is in effect or if the 812 * current process is using PMCs. If so, do exec() time 813 * processing. This processing needs to happen AFTER the 814 * P_INEXEC flag is cleared. 815 * 816 * The proc lock needs to be released before taking the PMC 817 * SX. 818 */ 819 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 820 PROC_UNLOCK(p); 821 VOP_UNLOCK(imgp->vp, 0); 822 pe.pm_credentialschanged = credential_changing; 823 pe.pm_entryaddr = imgp->entry_addr; 824 825 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 826 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 827 } else 828 PROC_UNLOCK(p); 829 #else /* !HWPMC_HOOKS */ 830 PROC_UNLOCK(p); 831 #endif 832 833 /* Set values passed into the program in registers. */ 834 if (p->p_sysent->sv_setregs) 835 (*p->p_sysent->sv_setregs)(td, imgp, 836 (u_long)(uintptr_t)stack_base); 837 else 838 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 839 840 vfs_mark_atime(imgp->vp, td->td_ucred); 841 842 SDT_PROBE(proc, kernel, , exec_success, args->fname, 0, 0, 0, 0); 843 844 done1: 845 /* 846 * Free any resources malloc'd earlier that we didn't use. 847 */ 848 uifree(euip); 849 if (newcred == NULL) 850 crfree(oldcred); 851 else 852 crfree(newcred); 853 VOP_UNLOCK(imgp->vp, 0); 854 855 /* 856 * Handle deferred decrement of ref counts. 857 */ 858 if (textvp != NULL) { 859 int tvfslocked; 860 861 tvfslocked = VFS_LOCK_GIANT(textvp->v_mount); 862 vrele(textvp); 863 VFS_UNLOCK_GIANT(tvfslocked); 864 } 865 if (binvp && error != 0) 866 vrele(binvp); 867 #ifdef KTRACE 868 if (tracevp != NULL) { 869 int tvfslocked; 870 871 tvfslocked = VFS_LOCK_GIANT(tracevp->v_mount); 872 vrele(tracevp); 873 VFS_UNLOCK_GIANT(tvfslocked); 874 } 875 if (tracecred != NULL) 876 crfree(tracecred); 877 #endif 878 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 879 pargs_drop(oldargs); 880 pargs_drop(newargs); 881 if (oldsigacts != NULL) 882 sigacts_free(oldsigacts); 883 884 exec_fail_dealloc: 885 886 /* 887 * free various allocated resources 888 */ 889 if (imgp->firstpage != NULL) 890 exec_unmap_first_page(imgp); 891 892 if (imgp->vp != NULL) { 893 if (args->fname) 894 NDFREE(&nd, NDF_ONLY_PNBUF); 895 if (imgp->opened) 896 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 897 vput(imgp->vp); 898 } 899 900 if (imgp->object != NULL) 901 vm_object_deallocate(imgp->object); 902 903 free(imgp->freepath, M_TEMP); 904 905 if (error == 0) { 906 PROC_LOCK(p); 907 td->td_dbgflags |= TDB_EXEC; 908 PROC_UNLOCK(p); 909 910 /* 911 * Stop the process here if its stop event mask has 912 * the S_EXEC bit set. 913 */ 914 STOPEVENT(p, S_EXEC, 0); 915 goto done2; 916 } 917 918 exec_fail: 919 /* we're done here, clear P_INEXEC */ 920 PROC_LOCK(p); 921 p->p_flag &= ~P_INEXEC; 922 PROC_UNLOCK(p); 923 924 SDT_PROBE(proc, kernel, , exec_failure, error, 0, 0, 0, 0); 925 926 done2: 927 #ifdef MAC 928 mac_execve_exit(imgp); 929 mac_execve_interpreter_exit(interpvplabel); 930 #endif 931 VFS_UNLOCK_GIANT(vfslocked); 932 exec_free_args(args); 933 934 if (error && imgp->vmspace_destroyed) { 935 /* sorry, no more process anymore. exit gracefully */ 936 exit1(td, W_EXITCODE(0, SIGABRT)); 937 /* NOT REACHED */ 938 } 939 940 #ifdef KTRACE 941 if (error == 0) 942 ktrprocctor(p); 943 #endif 944 945 return (error); 946 } 947 948 int 949 exec_map_first_page(imgp) 950 struct image_params *imgp; 951 { 952 int rv, i; 953 int initial_pagein; 954 vm_page_t ma[VM_INITIAL_PAGEIN]; 955 vm_object_t object; 956 957 if (imgp->firstpage != NULL) 958 exec_unmap_first_page(imgp); 959 960 object = imgp->vp->v_object; 961 if (object == NULL) 962 return (EACCES); 963 VM_OBJECT_LOCK(object); 964 #if VM_NRESERVLEVEL > 0 965 if ((object->flags & OBJ_COLORED) == 0) { 966 object->flags |= OBJ_COLORED; 967 object->pg_color = 0; 968 } 969 #endif 970 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 971 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 972 initial_pagein = VM_INITIAL_PAGEIN; 973 if (initial_pagein > object->size) 974 initial_pagein = object->size; 975 for (i = 1; i < initial_pagein; i++) { 976 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 977 if (ma[i]->valid) 978 break; 979 if ((ma[i]->oflags & VPO_BUSY) || ma[i]->busy) 980 break; 981 vm_page_busy(ma[i]); 982 } else { 983 ma[i] = vm_page_alloc(object, i, 984 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 985 if (ma[i] == NULL) 986 break; 987 } 988 } 989 initial_pagein = i; 990 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 991 ma[0] = vm_page_lookup(object, 0); 992 if ((rv != VM_PAGER_OK) || (ma[0] == NULL)) { 993 if (ma[0] != NULL) { 994 vm_page_lock(ma[0]); 995 vm_page_free(ma[0]); 996 vm_page_unlock(ma[0]); 997 } 998 VM_OBJECT_UNLOCK(object); 999 return (EIO); 1000 } 1001 } 1002 vm_page_lock(ma[0]); 1003 vm_page_hold(ma[0]); 1004 vm_page_unlock(ma[0]); 1005 vm_page_wakeup(ma[0]); 1006 VM_OBJECT_UNLOCK(object); 1007 1008 imgp->firstpage = sf_buf_alloc(ma[0], 0); 1009 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 1010 1011 return (0); 1012 } 1013 1014 void 1015 exec_unmap_first_page(imgp) 1016 struct image_params *imgp; 1017 { 1018 vm_page_t m; 1019 1020 if (imgp->firstpage != NULL) { 1021 m = sf_buf_page(imgp->firstpage); 1022 sf_buf_free(imgp->firstpage); 1023 imgp->firstpage = NULL; 1024 vm_page_lock(m); 1025 vm_page_unhold(m); 1026 vm_page_unlock(m); 1027 } 1028 } 1029 1030 /* 1031 * Destroy old address space, and allocate a new stack 1032 * The new stack is only SGROWSIZ large because it is grown 1033 * automatically in trap.c. 1034 */ 1035 int 1036 exec_new_vmspace(imgp, sv) 1037 struct image_params *imgp; 1038 struct sysentvec *sv; 1039 { 1040 int error; 1041 struct proc *p = imgp->proc; 1042 struct vmspace *vmspace = p->p_vmspace; 1043 vm_object_t obj; 1044 vm_offset_t sv_minuser, stack_addr; 1045 vm_map_t map; 1046 u_long ssiz; 1047 1048 imgp->vmspace_destroyed = 1; 1049 imgp->sysent = sv; 1050 1051 /* May be called with Giant held */ 1052 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1053 1054 /* 1055 * Blow away entire process VM, if address space not shared, 1056 * otherwise, create a new VM space so that other threads are 1057 * not disrupted 1058 */ 1059 map = &vmspace->vm_map; 1060 if (map_at_zero) 1061 sv_minuser = sv->sv_minuser; 1062 else 1063 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1064 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1065 vm_map_max(map) == sv->sv_maxuser) { 1066 shmexit(vmspace); 1067 pmap_remove_pages(vmspace_pmap(vmspace)); 1068 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1069 } else { 1070 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1071 if (error) 1072 return (error); 1073 vmspace = p->p_vmspace; 1074 map = &vmspace->vm_map; 1075 } 1076 1077 /* Map a shared page */ 1078 obj = sv->sv_shared_page_obj; 1079 if (obj != NULL) { 1080 vm_object_reference(obj); 1081 error = vm_map_fixed(map, obj, 0, 1082 sv->sv_shared_page_base, sv->sv_shared_page_len, 1083 VM_PROT_READ | VM_PROT_EXECUTE, VM_PROT_ALL, 1084 MAP_COPY_ON_WRITE | MAP_ACC_NO_CHARGE); 1085 if (error) { 1086 vm_object_deallocate(obj); 1087 return (error); 1088 } 1089 } 1090 1091 /* Allocate a new stack */ 1092 if (sv->sv_maxssiz != NULL) 1093 ssiz = *sv->sv_maxssiz; 1094 else 1095 ssiz = maxssiz; 1096 stack_addr = sv->sv_usrstack - ssiz; 1097 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1098 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1099 sv->sv_stackprot, 1100 VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1101 if (error) 1102 return (error); 1103 1104 #ifdef __ia64__ 1105 /* Allocate a new register stack */ 1106 stack_addr = IA64_BACKINGSTORE; 1107 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1108 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP); 1109 if (error) 1110 return (error); 1111 #endif 1112 1113 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 1114 * VM_STACK case, but they are still used to monitor the size of the 1115 * process stack so we can check the stack rlimit. 1116 */ 1117 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1118 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1119 1120 return (0); 1121 } 1122 1123 /* 1124 * Copy out argument and environment strings from the old process address 1125 * space into the temporary string buffer. 1126 */ 1127 int 1128 exec_copyin_args(struct image_args *args, char *fname, 1129 enum uio_seg segflg, char **argv, char **envv) 1130 { 1131 char *argp, *envp; 1132 int error; 1133 size_t length; 1134 1135 bzero(args, sizeof(*args)); 1136 if (argv == NULL) 1137 return (EFAULT); 1138 1139 /* 1140 * Allocate demand-paged memory for the file name, argument, and 1141 * environment strings. 1142 */ 1143 error = exec_alloc_args(args); 1144 if (error != 0) 1145 return (error); 1146 1147 /* 1148 * Copy the file name. 1149 */ 1150 if (fname != NULL) { 1151 args->fname = args->buf; 1152 error = (segflg == UIO_SYSSPACE) ? 1153 copystr(fname, args->fname, PATH_MAX, &length) : 1154 copyinstr(fname, args->fname, PATH_MAX, &length); 1155 if (error != 0) 1156 goto err_exit; 1157 } else 1158 length = 0; 1159 1160 args->begin_argv = args->buf + length; 1161 args->endp = args->begin_argv; 1162 args->stringspace = ARG_MAX; 1163 1164 /* 1165 * extract arguments first 1166 */ 1167 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 1168 if (argp == (caddr_t) -1) { 1169 error = EFAULT; 1170 goto err_exit; 1171 } 1172 if ((error = copyinstr(argp, args->endp, 1173 args->stringspace, &length))) { 1174 if (error == ENAMETOOLONG) 1175 error = E2BIG; 1176 goto err_exit; 1177 } 1178 args->stringspace -= length; 1179 args->endp += length; 1180 args->argc++; 1181 } 1182 1183 args->begin_envv = args->endp; 1184 1185 /* 1186 * extract environment strings 1187 */ 1188 if (envv) { 1189 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) { 1190 if (envp == (caddr_t)-1) { 1191 error = EFAULT; 1192 goto err_exit; 1193 } 1194 if ((error = copyinstr(envp, args->endp, 1195 args->stringspace, &length))) { 1196 if (error == ENAMETOOLONG) 1197 error = E2BIG; 1198 goto err_exit; 1199 } 1200 args->stringspace -= length; 1201 args->endp += length; 1202 args->envc++; 1203 } 1204 } 1205 1206 return (0); 1207 1208 err_exit: 1209 exec_free_args(args); 1210 return (error); 1211 } 1212 1213 /* 1214 * Allocate temporary demand-paged, zero-filled memory for the file name, 1215 * argument, and environment strings. Returns zero if the allocation succeeds 1216 * and ENOMEM otherwise. 1217 */ 1218 int 1219 exec_alloc_args(struct image_args *args) 1220 { 1221 1222 args->buf = (char *)kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 1223 return (args->buf != NULL ? 0 : ENOMEM); 1224 } 1225 1226 void 1227 exec_free_args(struct image_args *args) 1228 { 1229 1230 if (args->buf != NULL) { 1231 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf, 1232 PATH_MAX + ARG_MAX); 1233 args->buf = NULL; 1234 } 1235 if (args->fname_buf != NULL) { 1236 free(args->fname_buf, M_TEMP); 1237 args->fname_buf = NULL; 1238 } 1239 } 1240 1241 /* 1242 * Copy strings out to the new process address space, constructing new arg 1243 * and env vector tables. Return a pointer to the base so that it can be used 1244 * as the initial stack pointer. 1245 */ 1246 register_t * 1247 exec_copyout_strings(imgp) 1248 struct image_params *imgp; 1249 { 1250 int argc, envc; 1251 char **vectp; 1252 char *stringp, *destp; 1253 register_t *stack_base; 1254 struct ps_strings *arginfo; 1255 struct proc *p; 1256 size_t execpath_len; 1257 int szsigcode, szps; 1258 char canary[sizeof(long) * 8]; 1259 1260 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1261 /* 1262 * Calculate string base and vector table pointers. 1263 * Also deal with signal trampoline code for this exec type. 1264 */ 1265 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1266 execpath_len = strlen(imgp->execpath) + 1; 1267 else 1268 execpath_len = 0; 1269 p = imgp->proc; 1270 szsigcode = 0; 1271 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1272 if (p->p_sysent->sv_sigcode_base == 0) { 1273 if (p->p_sysent->sv_szsigcode != NULL) 1274 szsigcode = *(p->p_sysent->sv_szsigcode); 1275 } 1276 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 1277 roundup(execpath_len, sizeof(char *)) - 1278 roundup(sizeof(canary), sizeof(char *)) - 1279 roundup(szps, sizeof(char *)) - 1280 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *)); 1281 1282 /* 1283 * install sigcode 1284 */ 1285 if (szsigcode != 0) 1286 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo - 1287 szsigcode), szsigcode); 1288 1289 /* 1290 * Copy the image path for the rtld. 1291 */ 1292 if (execpath_len != 0) { 1293 imgp->execpathp = (uintptr_t)arginfo - szsigcode - execpath_len; 1294 copyout(imgp->execpath, (void *)imgp->execpathp, 1295 execpath_len); 1296 } 1297 1298 /* 1299 * Prepare the canary for SSP. 1300 */ 1301 arc4rand(canary, sizeof(canary), 0); 1302 imgp->canary = (uintptr_t)arginfo - szsigcode - execpath_len - 1303 sizeof(canary); 1304 copyout(canary, (void *)imgp->canary, sizeof(canary)); 1305 imgp->canarylen = sizeof(canary); 1306 1307 /* 1308 * Prepare the pagesizes array. 1309 */ 1310 imgp->pagesizes = (uintptr_t)arginfo - szsigcode - execpath_len - 1311 roundup(sizeof(canary), sizeof(char *)) - szps; 1312 copyout(pagesizes, (void *)imgp->pagesizes, szps); 1313 imgp->pagesizeslen = szps; 1314 1315 /* 1316 * If we have a valid auxargs ptr, prepare some room 1317 * on the stack. 1318 */ 1319 if (imgp->auxargs) { 1320 /* 1321 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1322 * lower compatibility. 1323 */ 1324 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1325 (AT_COUNT * 2); 1326 /* 1327 * The '+ 2' is for the null pointers at the end of each of 1328 * the arg and env vector sets,and imgp->auxarg_size is room 1329 * for argument of Runtime loader. 1330 */ 1331 vectp = (char **)(destp - (imgp->args->argc + 1332 imgp->args->envc + 2 + imgp->auxarg_size) 1333 * sizeof(char *)); 1334 } else { 1335 /* 1336 * The '+ 2' is for the null pointers at the end of each of 1337 * the arg and env vector sets 1338 */ 1339 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) * 1340 sizeof(char *)); 1341 } 1342 1343 /* 1344 * vectp also becomes our initial stack base 1345 */ 1346 stack_base = (register_t *)vectp; 1347 1348 stringp = imgp->args->begin_argv; 1349 argc = imgp->args->argc; 1350 envc = imgp->args->envc; 1351 1352 /* 1353 * Copy out strings - arguments and environment. 1354 */ 1355 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace); 1356 1357 /* 1358 * Fill in "ps_strings" struct for ps, w, etc. 1359 */ 1360 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1361 suword32(&arginfo->ps_nargvstr, argc); 1362 1363 /* 1364 * Fill in argument portion of vector table. 1365 */ 1366 for (; argc > 0; --argc) { 1367 suword(vectp++, (long)(intptr_t)destp); 1368 while (*stringp++ != 0) 1369 destp++; 1370 destp++; 1371 } 1372 1373 /* a null vector table pointer separates the argp's from the envp's */ 1374 suword(vectp++, 0); 1375 1376 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1377 suword32(&arginfo->ps_nenvstr, envc); 1378 1379 /* 1380 * Fill in environment portion of vector table. 1381 */ 1382 for (; envc > 0; --envc) { 1383 suword(vectp++, (long)(intptr_t)destp); 1384 while (*stringp++ != 0) 1385 destp++; 1386 destp++; 1387 } 1388 1389 /* end of vector table is a null pointer */ 1390 suword(vectp, 0); 1391 1392 return (stack_base); 1393 } 1394 1395 /* 1396 * Check permissions of file to execute. 1397 * Called with imgp->vp locked. 1398 * Return 0 for success or error code on failure. 1399 */ 1400 int 1401 exec_check_permissions(imgp) 1402 struct image_params *imgp; 1403 { 1404 struct vnode *vp = imgp->vp; 1405 struct vattr *attr = imgp->attr; 1406 struct thread *td; 1407 int error; 1408 1409 td = curthread; 1410 1411 /* Get file attributes */ 1412 error = VOP_GETATTR(vp, attr, td->td_ucred); 1413 if (error) 1414 return (error); 1415 1416 #ifdef MAC 1417 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1418 if (error) 1419 return (error); 1420 #endif 1421 1422 /* 1423 * 1) Check if file execution is disabled for the filesystem that 1424 * this file resides on. 1425 * 2) Ensure that at least one execute bit is on. Otherwise, a 1426 * privileged user will always succeed, and we don't want this 1427 * to happen unless the file really is executable. 1428 * 3) Ensure that the file is a regular file. 1429 */ 1430 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1431 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1432 (attr->va_type != VREG)) 1433 return (EACCES); 1434 1435 /* 1436 * Zero length files can't be exec'd 1437 */ 1438 if (attr->va_size == 0) 1439 return (ENOEXEC); 1440 1441 /* 1442 * Check for execute permission to file based on current credentials. 1443 */ 1444 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1445 if (error) 1446 return (error); 1447 1448 /* 1449 * Check number of open-for-writes on the file and deny execution 1450 * if there are any. 1451 */ 1452 if (vp->v_writecount) 1453 return (ETXTBSY); 1454 1455 /* 1456 * Call filesystem specific open routine (which does nothing in the 1457 * general case). 1458 */ 1459 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1460 if (error == 0) 1461 imgp->opened = 1; 1462 return (error); 1463 } 1464 1465 /* 1466 * Exec handler registration 1467 */ 1468 int 1469 exec_register(execsw_arg) 1470 const struct execsw *execsw_arg; 1471 { 1472 const struct execsw **es, **xs, **newexecsw; 1473 int count = 2; /* New slot and trailing NULL */ 1474 1475 if (execsw) 1476 for (es = execsw; *es; es++) 1477 count++; 1478 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1479 if (newexecsw == NULL) 1480 return (ENOMEM); 1481 xs = newexecsw; 1482 if (execsw) 1483 for (es = execsw; *es; es++) 1484 *xs++ = *es; 1485 *xs++ = execsw_arg; 1486 *xs = NULL; 1487 if (execsw) 1488 free(execsw, M_TEMP); 1489 execsw = newexecsw; 1490 return (0); 1491 } 1492 1493 int 1494 exec_unregister(execsw_arg) 1495 const struct execsw *execsw_arg; 1496 { 1497 const struct execsw **es, **xs, **newexecsw; 1498 int count = 1; 1499 1500 if (execsw == NULL) 1501 panic("unregister with no handlers left?\n"); 1502 1503 for (es = execsw; *es; es++) { 1504 if (*es == execsw_arg) 1505 break; 1506 } 1507 if (*es == NULL) 1508 return (ENOENT); 1509 for (es = execsw; *es; es++) 1510 if (*es != execsw_arg) 1511 count++; 1512 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1513 if (newexecsw == NULL) 1514 return (ENOMEM); 1515 xs = newexecsw; 1516 for (es = execsw; *es; es++) 1517 if (*es != execsw_arg) 1518 *xs++ = *es; 1519 *xs = NULL; 1520 if (execsw) 1521 free(execsw, M_TEMP); 1522 execsw = newexecsw; 1523 return (0); 1524 } 1525 1526 static vm_object_t shared_page_obj; 1527 static int shared_page_free; 1528 1529 int 1530 shared_page_fill(int size, int align, const char *data) 1531 { 1532 vm_page_t m; 1533 struct sf_buf *s; 1534 vm_offset_t sk; 1535 int res; 1536 1537 VM_OBJECT_LOCK(shared_page_obj); 1538 m = vm_page_grab(shared_page_obj, 0, VM_ALLOC_RETRY); 1539 res = roundup(shared_page_free, align); 1540 if (res + size >= IDX_TO_OFF(shared_page_obj->size)) 1541 res = -1; 1542 else { 1543 VM_OBJECT_UNLOCK(shared_page_obj); 1544 s = sf_buf_alloc(m, SFB_DEFAULT); 1545 sk = sf_buf_kva(s); 1546 bcopy(data, (void *)(sk + res), size); 1547 shared_page_free = res + size; 1548 sf_buf_free(s); 1549 VM_OBJECT_LOCK(shared_page_obj); 1550 } 1551 vm_page_wakeup(m); 1552 VM_OBJECT_UNLOCK(shared_page_obj); 1553 return (res); 1554 } 1555 1556 static void 1557 shared_page_init(void *dummy __unused) 1558 { 1559 vm_page_t m; 1560 1561 shared_page_obj = vm_pager_allocate(OBJT_PHYS, 0, PAGE_SIZE, 1562 VM_PROT_DEFAULT, 0, NULL); 1563 VM_OBJECT_LOCK(shared_page_obj); 1564 m = vm_page_grab(shared_page_obj, 0, VM_ALLOC_RETRY | VM_ALLOC_NOBUSY | 1565 VM_ALLOC_ZERO); 1566 m->valid = VM_PAGE_BITS_ALL; 1567 VM_OBJECT_UNLOCK(shared_page_obj); 1568 } 1569 1570 SYSINIT(shp, SI_SUB_EXEC, SI_ORDER_FIRST, (sysinit_cfunc_t)shared_page_init, 1571 NULL); 1572 1573 void 1574 exec_sysvec_init(void *param) 1575 { 1576 struct sysentvec *sv; 1577 1578 sv = (struct sysentvec *)param; 1579 1580 if ((sv->sv_flags & SV_SHP) == 0) 1581 return; 1582 sv->sv_shared_page_obj = shared_page_obj; 1583 sv->sv_sigcode_base = sv->sv_shared_page_base + 1584 shared_page_fill(*(sv->sv_szsigcode), 16, sv->sv_sigcode); 1585 }
Cache object: 417d8ae9074083e98e73f53388bfa8e3
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