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_hwpmc_hooks.h" 31 #include "opt_kdtrace.h" 32 #include "opt_ktrace.h" 33 #include "opt_mac.h" 34 #include "opt_vm.h" 35 36 #include <sys/param.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/sdt.h> 59 #include <sys/sf_buf.h> 60 #include <sys/syscallsubr.h> 61 #include <sys/sysent.h> 62 #include <sys/shm.h> 63 #include <sys/sysctl.h> 64 #include <sys/vnode.h> 65 #ifdef KTRACE 66 #include <sys/ktrace.h> 67 #endif 68 69 #include <vm/vm.h> 70 #include <vm/vm_param.h> 71 #include <vm/pmap.h> 72 #include <vm/vm_page.h> 73 #include <vm/vm_map.h> 74 #include <vm/vm_kern.h> 75 #include <vm/vm_extern.h> 76 #include <vm/vm_object.h> 77 #include <vm/vm_pager.h> 78 79 #ifdef HWPMC_HOOKS 80 #include <sys/pmckern.h> 81 #endif 82 83 #include <machine/reg.h> 84 85 #include <security/audit/audit.h> 86 #include <security/mac/mac_framework.h> 87 88 #ifdef KDTRACE_HOOKS 89 #include <sys/dtrace_bsd.h> 90 dtrace_execexit_func_t dtrace_fasttrap_exec; 91 #endif 92 93 SDT_PROVIDER_DECLARE(proc); 94 SDT_PROBE_DEFINE(proc, kernel, , exec); 95 SDT_PROBE_ARGTYPE(proc, kernel, , exec, 0, "char *"); 96 SDT_PROBE_DEFINE(proc, kernel, , exec_failure); 97 SDT_PROBE_ARGTYPE(proc, kernel, , exec_failure, 0, "int"); 98 SDT_PROBE_DEFINE(proc, kernel, , exec_success); 99 SDT_PROBE_ARGTYPE(proc, kernel, , exec_success, 0, "char *"); 100 101 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 102 103 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 104 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 105 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 106 static int do_execve(struct thread *td, struct image_args *args, 107 struct mac *mac_p); 108 static void exec_free_args(struct image_args *); 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 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 126 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 127 { 128 struct proc *p; 129 int error; 130 131 p = curproc; 132 #ifdef SCTL_MASK32 133 if (req->flags & SCTL_MASK32) { 134 unsigned int val; 135 val = (unsigned int)p->p_sysent->sv_psstrings; 136 error = SYSCTL_OUT(req, &val, sizeof(val)); 137 } else 138 #endif 139 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 140 sizeof(p->p_sysent->sv_psstrings)); 141 return error; 142 } 143 144 static int 145 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 146 { 147 struct proc *p; 148 int error; 149 150 p = curproc; 151 #ifdef SCTL_MASK32 152 if (req->flags & SCTL_MASK32) { 153 unsigned int val; 154 val = (unsigned int)p->p_sysent->sv_usrstack; 155 error = SYSCTL_OUT(req, &val, sizeof(val)); 156 } else 157 #endif 158 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 159 sizeof(p->p_sysent->sv_usrstack)); 160 return error; 161 } 162 163 static int 164 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 165 { 166 struct proc *p; 167 168 p = curproc; 169 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 170 sizeof(p->p_sysent->sv_stackprot))); 171 } 172 173 /* 174 * Each of the items is a pointer to a `const struct execsw', hence the 175 * double pointer here. 176 */ 177 static const struct execsw **execsw; 178 179 #ifndef _SYS_SYSPROTO_H_ 180 struct execve_args { 181 char *fname; 182 char **argv; 183 char **envv; 184 }; 185 #endif 186 187 int 188 execve(td, uap) 189 struct thread *td; 190 struct execve_args /* { 191 char *fname; 192 char **argv; 193 char **envv; 194 } */ *uap; 195 { 196 int error; 197 struct image_args args; 198 199 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 200 uap->argv, uap->envv); 201 if (error == 0) 202 error = kern_execve(td, &args, NULL); 203 return (error); 204 } 205 206 #ifndef _SYS_SYSPROTO_H_ 207 struct fexecve_args { 208 int fd; 209 char **argv; 210 char **envv; 211 } 212 #endif 213 int 214 fexecve(struct thread *td, struct fexecve_args *uap) 215 { 216 int error; 217 struct image_args args; 218 219 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 220 uap->argv, uap->envv); 221 if (error == 0) { 222 args.fd = uap->fd; 223 error = kern_execve(td, &args, NULL); 224 } 225 return (error); 226 } 227 228 #ifndef _SYS_SYSPROTO_H_ 229 struct __mac_execve_args { 230 char *fname; 231 char **argv; 232 char **envv; 233 struct mac *mac_p; 234 }; 235 #endif 236 237 int 238 __mac_execve(td, uap) 239 struct thread *td; 240 struct __mac_execve_args /* { 241 char *fname; 242 char **argv; 243 char **envv; 244 struct mac *mac_p; 245 } */ *uap; 246 { 247 #ifdef MAC 248 int error; 249 struct image_args args; 250 251 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 252 uap->argv, uap->envv); 253 if (error == 0) 254 error = kern_execve(td, &args, uap->mac_p); 255 return (error); 256 #else 257 return (ENOSYS); 258 #endif 259 } 260 261 /* 262 * XXX: kern_execve has the astonishing property of not always returning to 263 * the caller. If sufficiently bad things happen during the call to 264 * do_execve(), it can end up calling exit1(); as a result, callers must 265 * avoid doing anything which they might need to undo (e.g., allocating 266 * memory). 267 */ 268 int 269 kern_execve(td, args, mac_p) 270 struct thread *td; 271 struct image_args *args; 272 struct mac *mac_p; 273 { 274 struct proc *p = td->td_proc; 275 int error; 276 277 AUDIT_ARG(argv, args->begin_argv, args->argc, 278 args->begin_envv - args->begin_argv); 279 AUDIT_ARG(envv, args->begin_envv, args->envc, 280 args->endp - args->begin_envv); 281 if (p->p_flag & P_HADTHREADS) { 282 PROC_LOCK(p); 283 if (thread_single(SINGLE_BOUNDARY)) { 284 PROC_UNLOCK(p); 285 exec_free_args(args); 286 return (ERESTART); /* Try again later. */ 287 } 288 PROC_UNLOCK(p); 289 } 290 291 error = do_execve(td, args, mac_p); 292 293 if (p->p_flag & P_HADTHREADS) { 294 PROC_LOCK(p); 295 /* 296 * If success, we upgrade to SINGLE_EXIT state to 297 * force other threads to suicide. 298 */ 299 if (error == 0) 300 thread_single(SINGLE_EXIT); 301 else 302 thread_single_end(); 303 PROC_UNLOCK(p); 304 } 305 306 return (error); 307 } 308 309 /* 310 * In-kernel implementation of execve(). All arguments are assumed to be 311 * userspace pointers from the passed thread. 312 */ 313 static int 314 do_execve(td, args, mac_p) 315 struct thread *td; 316 struct image_args *args; 317 struct mac *mac_p; 318 { 319 struct proc *p = td->td_proc; 320 struct nameidata nd, *ndp; 321 struct ucred *newcred = NULL, *oldcred; 322 struct uidinfo *euip; 323 register_t *stack_base; 324 int error, len = 0, i; 325 struct image_params image_params, *imgp; 326 struct vattr attr; 327 int (*img_first)(struct image_params *); 328 struct pargs *oldargs = NULL, *newargs = NULL; 329 struct sigacts *oldsigacts, *newsigacts; 330 #ifdef KTRACE 331 struct vnode *tracevp = NULL; 332 struct ucred *tracecred = NULL; 333 #endif 334 struct vnode *textvp = NULL, *binvp = NULL; 335 int credential_changing; 336 int vfslocked; 337 int textset; 338 #ifdef MAC 339 struct label *interplabel = NULL; 340 int will_transition; 341 #endif 342 #ifdef HWPMC_HOOKS 343 struct pmckern_procexec pe; 344 #endif 345 static const char fexecv_proc_title[] = "(fexecv)"; 346 347 vfslocked = 0; 348 imgp = &image_params; 349 350 /* 351 * Lock the process and set the P_INEXEC flag to indicate that 352 * it should be left alone until we're done here. This is 353 * necessary to avoid race conditions - e.g. in ptrace() - 354 * that might allow a local user to illicitly obtain elevated 355 * privileges. 356 */ 357 PROC_LOCK(p); 358 KASSERT((p->p_flag & P_INEXEC) == 0, 359 ("%s(): process already has P_INEXEC flag", __func__)); 360 p->p_flag |= P_INEXEC; 361 PROC_UNLOCK(p); 362 363 /* 364 * Initialize part of the common data 365 */ 366 imgp->proc = p; 367 imgp->execlabel = NULL; 368 imgp->attr = &attr; 369 imgp->entry_addr = 0; 370 imgp->vmspace_destroyed = 0; 371 imgp->interpreted = 0; 372 imgp->opened = 0; 373 imgp->interpreter_name = args->buf + PATH_MAX + ARG_MAX; 374 imgp->auxargs = NULL; 375 imgp->vp = NULL; 376 imgp->object = NULL; 377 imgp->firstpage = NULL; 378 imgp->ps_strings = 0; 379 imgp->auxarg_size = 0; 380 imgp->args = args; 381 382 #ifdef MAC 383 error = mac_execve_enter(imgp, mac_p); 384 if (error) 385 goto exec_fail; 386 #endif 387 388 imgp->image_header = NULL; 389 390 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 391 392 /* 393 * Translate the file name. namei() returns a vnode pointer 394 * in ni_vp amoung other things. 395 * 396 * XXXAUDIT: It would be desirable to also audit the name of the 397 * interpreter if this is an interpreted binary. 398 */ 399 if (args->fname != NULL) { 400 ndp = &nd; 401 NDINIT(ndp, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 402 | MPSAFE | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 403 } 404 405 interpret: 406 if (args->fname != NULL) { 407 error = namei(ndp); 408 if (error) 409 goto exec_fail; 410 411 vfslocked = NDHASGIANT(ndp); 412 binvp = ndp->ni_vp; 413 imgp->vp = binvp; 414 } else { 415 error = fgetvp(td, args->fd, &binvp); 416 if (error) 417 goto exec_fail; 418 vfslocked = VFS_LOCK_GIANT(binvp->v_mount); 419 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY); 420 imgp->vp = binvp; 421 } 422 423 /* 424 * Check file permissions (also 'opens' file) 425 */ 426 error = exec_check_permissions(imgp); 427 if (error) 428 goto exec_fail_dealloc; 429 430 imgp->object = imgp->vp->v_object; 431 if (imgp->object != NULL) 432 vm_object_reference(imgp->object); 433 434 /* 435 * Set VV_TEXT now so no one can write to the executable while we're 436 * activating it. 437 * 438 * Remember if this was set before and unset it in case this is not 439 * actually an executable image. 440 */ 441 textset = imgp->vp->v_vflag & VV_TEXT; 442 imgp->vp->v_vflag |= VV_TEXT; 443 444 error = exec_map_first_page(imgp); 445 if (error) 446 goto exec_fail_dealloc; 447 448 imgp->proc->p_osrel = 0; 449 /* 450 * If the current process has a special image activator it 451 * wants to try first, call it. For example, emulating shell 452 * scripts differently. 453 */ 454 error = -1; 455 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 456 error = img_first(imgp); 457 458 /* 459 * Loop through the list of image activators, calling each one. 460 * An activator returns -1 if there is no match, 0 on success, 461 * and an error otherwise. 462 */ 463 for (i = 0; error == -1 && execsw[i]; ++i) { 464 if (execsw[i]->ex_imgact == NULL || 465 execsw[i]->ex_imgact == img_first) { 466 continue; 467 } 468 error = (*execsw[i]->ex_imgact)(imgp); 469 } 470 471 if (error) { 472 if (error == -1) { 473 if (textset == 0) 474 imgp->vp->v_vflag &= ~VV_TEXT; 475 error = ENOEXEC; 476 } 477 goto exec_fail_dealloc; 478 } 479 480 /* 481 * Special interpreter operation, cleanup and loop up to try to 482 * activate the interpreter. 483 */ 484 if (imgp->interpreted) { 485 exec_unmap_first_page(imgp); 486 /* 487 * VV_TEXT needs to be unset for scripts. There is a short 488 * period before we determine that something is a script where 489 * VV_TEXT will be set. The vnode lock is held over this 490 * entire period so nothing should illegitimately be blocked. 491 */ 492 imgp->vp->v_vflag &= ~VV_TEXT; 493 /* free name buffer and old vnode */ 494 if (args->fname != NULL) 495 NDFREE(ndp, NDF_ONLY_PNBUF); 496 #ifdef MAC 497 interplabel = mac_vnode_label_alloc(); 498 mac_vnode_copy_label(binvp->v_label, interplabel); 499 #endif 500 if (imgp->opened) { 501 VOP_CLOSE(binvp, FREAD, td->td_ucred, td); 502 imgp->opened = 0; 503 } 504 vput(binvp); 505 vm_object_deallocate(imgp->object); 506 imgp->object = NULL; 507 VFS_UNLOCK_GIANT(vfslocked); 508 vfslocked = 0; 509 /* set new name to that of the interpreter */ 510 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME | MPSAFE, 511 UIO_SYSSPACE, imgp->interpreter_name, td); 512 args->fname = imgp->interpreter_name; 513 goto interpret; 514 } 515 516 /* 517 * NB: We unlock the vnode here because it is believed that none 518 * of the sv_copyout_strings/sv_fixup operations require the vnode. 519 */ 520 VOP_UNLOCK(imgp->vp, 0); 521 /* 522 * Copy out strings (args and env) and initialize stack base 523 */ 524 if (p->p_sysent->sv_copyout_strings) 525 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 526 else 527 stack_base = exec_copyout_strings(imgp); 528 529 /* 530 * If custom stack fixup routine present for this process 531 * let it do the stack setup. 532 * Else stuff argument count as first item on stack 533 */ 534 if (p->p_sysent->sv_fixup != NULL) 535 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 536 else 537 suword(--stack_base, imgp->args->argc); 538 539 /* 540 * For security and other reasons, the file descriptor table cannot 541 * be shared after an exec. 542 */ 543 fdunshare(p, td); 544 545 /* 546 * Malloc things before we need locks. 547 */ 548 newcred = crget(); 549 euip = uifind(attr.va_uid); 550 i = imgp->args->begin_envv - imgp->args->begin_argv; 551 /* Cache arguments if they fit inside our allowance */ 552 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 553 newargs = pargs_alloc(i); 554 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 555 } 556 557 /* close files on exec */ 558 fdcloseexec(td); 559 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 560 561 /* Get a reference to the vnode prior to locking the proc */ 562 VREF(binvp); 563 564 /* 565 * For security and other reasons, signal handlers cannot 566 * be shared after an exec. The new process gets a copy of the old 567 * handlers. In execsigs(), the new process will have its signals 568 * reset. 569 */ 570 PROC_LOCK(p); 571 if (sigacts_shared(p->p_sigacts)) { 572 oldsigacts = p->p_sigacts; 573 PROC_UNLOCK(p); 574 newsigacts = sigacts_alloc(); 575 sigacts_copy(newsigacts, oldsigacts); 576 PROC_LOCK(p); 577 p->p_sigacts = newsigacts; 578 } else 579 oldsigacts = NULL; 580 581 /* Stop profiling */ 582 stopprofclock(p); 583 584 /* reset caught signals */ 585 execsigs(p); 586 587 /* name this process - nameiexec(p, ndp) */ 588 if (args->fname) { 589 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 590 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 591 } else { 592 len = MAXCOMLEN; 593 if (vn_commname(binvp, p->p_comm, MAXCOMLEN + 1) == 0) 594 len = MAXCOMLEN; 595 else { 596 len = sizeof(fexecv_proc_title); 597 bcopy(fexecv_proc_title, p->p_comm, len); 598 } 599 } 600 p->p_comm[len] = 0; 601 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 602 603 /* 604 * mark as execed, wakeup the process that vforked (if any) and tell 605 * it that it now has its own resources back 606 */ 607 p->p_flag |= P_EXEC; 608 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 609 p->p_flag &= ~P_PPWAIT; 610 wakeup(p->p_pptr); 611 } 612 613 /* 614 * Implement image setuid/setgid. 615 * 616 * Don't honor setuid/setgid if the filesystem prohibits it or if 617 * the process is being traced. 618 * 619 * XXXMAC: For the time being, use NOSUID to also prohibit 620 * transitions on the file system. 621 */ 622 oldcred = p->p_ucred; 623 credential_changing = 0; 624 credential_changing |= (attr.va_mode & VSUID) && oldcred->cr_uid != 625 attr.va_uid; 626 credential_changing |= (attr.va_mode & VSGID) && oldcred->cr_gid != 627 attr.va_gid; 628 #ifdef MAC 629 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 630 interplabel, imgp); 631 credential_changing |= will_transition; 632 #endif 633 634 if (credential_changing && 635 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 636 (p->p_flag & P_TRACED) == 0) { 637 /* 638 * Turn off syscall tracing for set-id programs, except for 639 * root. Record any set-id flags first to make sure that 640 * we do not regain any tracing during a possible block. 641 */ 642 setsugid(p); 643 644 #ifdef KTRACE 645 if (p->p_tracevp != NULL && 646 priv_check_cred(oldcred, PRIV_DEBUG_DIFFCRED, 0)) { 647 mtx_lock(&ktrace_mtx); 648 p->p_traceflag = 0; 649 tracevp = p->p_tracevp; 650 p->p_tracevp = NULL; 651 tracecred = p->p_tracecred; 652 p->p_tracecred = NULL; 653 mtx_unlock(&ktrace_mtx); 654 } 655 #endif 656 /* 657 * Close any file descriptors 0..2 that reference procfs, 658 * then make sure file descriptors 0..2 are in use. 659 * 660 * setugidsafety() may call closef() and then pfind() 661 * which may grab the process lock. 662 * fdcheckstd() may call falloc() which may block to 663 * allocate memory, so temporarily drop the process lock. 664 */ 665 PROC_UNLOCK(p); 666 setugidsafety(td); 667 VOP_UNLOCK(imgp->vp, 0); 668 error = fdcheckstd(td); 669 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 670 if (error != 0) 671 goto done1; 672 PROC_LOCK(p); 673 /* 674 * Set the new credentials. 675 */ 676 crcopy(newcred, oldcred); 677 if (attr.va_mode & VSUID) 678 change_euid(newcred, euip); 679 if (attr.va_mode & VSGID) 680 change_egid(newcred, attr.va_gid); 681 #ifdef MAC 682 if (will_transition) { 683 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 684 interplabel, imgp); 685 } 686 #endif 687 /* 688 * Implement correct POSIX saved-id behavior. 689 * 690 * XXXMAC: Note that the current logic will save the 691 * uid and gid if a MAC domain transition occurs, even 692 * though maybe it shouldn't. 693 */ 694 change_svuid(newcred, newcred->cr_uid); 695 change_svgid(newcred, newcred->cr_gid); 696 p->p_ucred = newcred; 697 newcred = NULL; 698 } else { 699 if (oldcred->cr_uid == oldcred->cr_ruid && 700 oldcred->cr_gid == oldcred->cr_rgid) 701 p->p_flag &= ~P_SUGID; 702 /* 703 * Implement correct POSIX saved-id behavior. 704 * 705 * XXX: It's not clear that the existing behavior is 706 * POSIX-compliant. A number of sources indicate that the 707 * saved uid/gid should only be updated if the new ruid is 708 * not equal to the old ruid, or the new euid is not equal 709 * to the old euid and the new euid is not equal to the old 710 * ruid. The FreeBSD code always updates the saved uid/gid. 711 * Also, this code uses the new (replaced) euid and egid as 712 * the source, which may or may not be the right ones to use. 713 */ 714 if (oldcred->cr_svuid != oldcred->cr_uid || 715 oldcred->cr_svgid != oldcred->cr_gid) { 716 crcopy(newcred, oldcred); 717 change_svuid(newcred, newcred->cr_uid); 718 change_svgid(newcred, newcred->cr_gid); 719 p->p_ucred = newcred; 720 newcred = NULL; 721 } 722 } 723 724 /* 725 * Store the vp for use in procfs. This vnode was referenced prior 726 * to locking the proc lock. 727 */ 728 textvp = p->p_textvp; 729 p->p_textvp = binvp; 730 731 #ifdef KDTRACE_HOOKS 732 /* 733 * Tell the DTrace fasttrap provider about the exec if it 734 * has declared an interest. 735 */ 736 if (dtrace_fasttrap_exec) 737 dtrace_fasttrap_exec(p); 738 #endif 739 740 /* 741 * Notify others that we exec'd, and clear the P_INEXEC flag 742 * as we're now a bona fide freshly-execed process. 743 */ 744 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 745 p->p_flag &= ~P_INEXEC; 746 747 /* 748 * If tracing the process, trap to debugger so breakpoints 749 * can be set before the program executes. 750 * Use tdsignal to deliver signal to current thread, use 751 * psignal may cause the signal to be delivered to wrong thread 752 * because that thread will exit, remember we are going to enter 753 * single thread mode. 754 */ 755 if (p->p_flag & P_TRACED) 756 tdsignal(p, td, SIGTRAP, NULL); 757 758 /* clear "fork but no exec" flag, as we _are_ execing */ 759 p->p_acflag &= ~AFORK; 760 761 /* 762 * Free any previous argument cache and replace it with 763 * the new argument cache, if any. 764 */ 765 oldargs = p->p_args; 766 p->p_args = newargs; 767 newargs = NULL; 768 769 #ifdef HWPMC_HOOKS 770 /* 771 * Check if system-wide sampling is in effect or if the 772 * current process is using PMCs. If so, do exec() time 773 * processing. This processing needs to happen AFTER the 774 * P_INEXEC flag is cleared. 775 * 776 * The proc lock needs to be released before taking the PMC 777 * SX. 778 */ 779 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 780 PROC_UNLOCK(p); 781 pe.pm_credentialschanged = credential_changing; 782 pe.pm_entryaddr = imgp->entry_addr; 783 784 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 785 } else 786 PROC_UNLOCK(p); 787 #else /* !HWPMC_HOOKS */ 788 PROC_UNLOCK(p); 789 #endif 790 791 /* Set values passed into the program in registers. */ 792 if (p->p_sysent->sv_setregs) 793 (*p->p_sysent->sv_setregs)(td, imgp->entry_addr, 794 (u_long)(uintptr_t)stack_base, imgp->ps_strings); 795 else 796 exec_setregs(td, imgp->entry_addr, 797 (u_long)(uintptr_t)stack_base, imgp->ps_strings); 798 799 vfs_mark_atime(imgp->vp, td); 800 801 done1: 802 803 /* 804 * Free any resources malloc'd earlier that we didn't use. 805 */ 806 uifree(euip); 807 if (newcred == NULL) 808 crfree(oldcred); 809 else 810 crfree(newcred); 811 VOP_UNLOCK(imgp->vp, 0); 812 813 SDT_PROBE(proc, kernel, , exec_success, args->fname, 0, 0, 0, 0); 814 815 /* 816 * Handle deferred decrement of ref counts. 817 */ 818 if (textvp != NULL) { 819 int tvfslocked; 820 821 tvfslocked = VFS_LOCK_GIANT(textvp->v_mount); 822 vrele(textvp); 823 VFS_UNLOCK_GIANT(tvfslocked); 824 } 825 if (binvp && error != 0) 826 vrele(binvp); 827 #ifdef KTRACE 828 if (tracevp != NULL) { 829 int tvfslocked; 830 831 tvfslocked = VFS_LOCK_GIANT(tracevp->v_mount); 832 vrele(tracevp); 833 VFS_UNLOCK_GIANT(tvfslocked); 834 } 835 if (tracecred != NULL) 836 crfree(tracecred); 837 #endif 838 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 839 pargs_drop(oldargs); 840 pargs_drop(newargs); 841 if (oldsigacts != NULL) 842 sigacts_free(oldsigacts); 843 844 exec_fail_dealloc: 845 846 /* 847 * free various allocated resources 848 */ 849 if (imgp->firstpage != NULL) 850 exec_unmap_first_page(imgp); 851 852 if (imgp->vp != NULL) { 853 if (args->fname) 854 NDFREE(ndp, NDF_ONLY_PNBUF); 855 if (imgp->opened) 856 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 857 vput(imgp->vp); 858 } 859 860 if (imgp->object != NULL) 861 vm_object_deallocate(imgp->object); 862 863 if (error == 0) { 864 /* 865 * Stop the process here if its stop event mask has 866 * the S_EXEC bit set. 867 */ 868 STOPEVENT(p, S_EXEC, 0); 869 goto done2; 870 } 871 872 exec_fail: 873 /* we're done here, clear P_INEXEC */ 874 PROC_LOCK(p); 875 p->p_flag &= ~P_INEXEC; 876 PROC_UNLOCK(p); 877 878 SDT_PROBE(proc, kernel, , exec_failure, error, 0, 0, 0, 0); 879 880 done2: 881 #ifdef MAC 882 mac_execve_exit(imgp); 883 if (interplabel != NULL) 884 mac_vnode_label_free(interplabel); 885 #endif 886 VFS_UNLOCK_GIANT(vfslocked); 887 exec_free_args(args); 888 889 if (error && imgp->vmspace_destroyed) { 890 /* sorry, no more process anymore. exit gracefully */ 891 exit1(td, W_EXITCODE(0, SIGABRT)); 892 /* NOT REACHED */ 893 } 894 return (error); 895 } 896 897 int 898 exec_map_first_page(imgp) 899 struct image_params *imgp; 900 { 901 int rv, i; 902 int initial_pagein; 903 vm_page_t ma[VM_INITIAL_PAGEIN]; 904 vm_object_t object; 905 906 if (imgp->firstpage != NULL) 907 exec_unmap_first_page(imgp); 908 909 object = imgp->vp->v_object; 910 if (object == NULL) 911 return (EACCES); 912 VM_OBJECT_LOCK(object); 913 #if VM_NRESERVLEVEL > 0 914 if ((object->flags & OBJ_COLORED) == 0) { 915 object->flags |= OBJ_COLORED; 916 object->pg_color = 0; 917 } 918 #endif 919 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 920 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 921 initial_pagein = VM_INITIAL_PAGEIN; 922 if (initial_pagein > object->size) 923 initial_pagein = object->size; 924 for (i = 1; i < initial_pagein; i++) { 925 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 926 if (ma[i]->valid) 927 break; 928 if ((ma[i]->oflags & VPO_BUSY) || ma[i]->busy) 929 break; 930 vm_page_busy(ma[i]); 931 } else { 932 ma[i] = vm_page_alloc(object, i, 933 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 934 if (ma[i] == NULL) 935 break; 936 } 937 } 938 initial_pagein = i; 939 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 940 ma[0] = vm_page_lookup(object, 0); 941 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || 942 (ma[0]->valid == 0)) { 943 if (ma[0]) { 944 vm_page_lock_queues(); 945 vm_page_free(ma[0]); 946 vm_page_unlock_queues(); 947 } 948 VM_OBJECT_UNLOCK(object); 949 return (EIO); 950 } 951 } 952 vm_page_lock_queues(); 953 vm_page_hold(ma[0]); 954 vm_page_unlock_queues(); 955 vm_page_wakeup(ma[0]); 956 VM_OBJECT_UNLOCK(object); 957 958 imgp->firstpage = sf_buf_alloc(ma[0], 0); 959 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 960 961 return (0); 962 } 963 964 void 965 exec_unmap_first_page(imgp) 966 struct image_params *imgp; 967 { 968 vm_page_t m; 969 970 if (imgp->firstpage != NULL) { 971 m = sf_buf_page(imgp->firstpage); 972 sf_buf_free(imgp->firstpage); 973 imgp->firstpage = NULL; 974 vm_page_lock_queues(); 975 vm_page_unhold(m); 976 vm_page_unlock_queues(); 977 } 978 } 979 980 /* 981 * Destroy old address space, and allocate a new stack 982 * The new stack is only SGROWSIZ large because it is grown 983 * automatically in trap.c. 984 */ 985 int 986 exec_new_vmspace(imgp, sv) 987 struct image_params *imgp; 988 struct sysentvec *sv; 989 { 990 int error; 991 struct proc *p = imgp->proc; 992 struct vmspace *vmspace = p->p_vmspace; 993 vm_offset_t stack_addr; 994 vm_map_t map; 995 u_long ssiz; 996 997 imgp->vmspace_destroyed = 1; 998 imgp->sysent = sv; 999 1000 /* May be called with Giant held */ 1001 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1002 1003 /* 1004 * Blow away entire process VM, if address space not shared, 1005 * otherwise, create a new VM space so that other threads are 1006 * not disrupted 1007 */ 1008 map = &vmspace->vm_map; 1009 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv->sv_minuser && 1010 vm_map_max(map) == sv->sv_maxuser) { 1011 shmexit(vmspace); 1012 pmap_remove_pages(vmspace_pmap(vmspace)); 1013 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1014 } else { 1015 error = vmspace_exec(p, sv->sv_minuser, sv->sv_maxuser); 1016 if (error) 1017 return (error); 1018 vmspace = p->p_vmspace; 1019 map = &vmspace->vm_map; 1020 } 1021 1022 /* Allocate a new stack */ 1023 if (sv->sv_maxssiz != NULL) 1024 ssiz = *sv->sv_maxssiz; 1025 else 1026 ssiz = maxssiz; 1027 stack_addr = sv->sv_usrstack - ssiz; 1028 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1029 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1030 if (error) 1031 return (error); 1032 1033 #ifdef __ia64__ 1034 /* Allocate a new register stack */ 1035 stack_addr = IA64_BACKINGSTORE; 1036 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1037 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP); 1038 if (error) 1039 return (error); 1040 #endif 1041 1042 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 1043 * VM_STACK case, but they are still used to monitor the size of the 1044 * process stack so we can check the stack rlimit. 1045 */ 1046 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1047 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1048 1049 return (0); 1050 } 1051 1052 /* 1053 * Copy out argument and environment strings from the old process address 1054 * space into the temporary string buffer. 1055 */ 1056 int 1057 exec_copyin_args(struct image_args *args, char *fname, 1058 enum uio_seg segflg, char **argv, char **envv) 1059 { 1060 char *argp, *envp; 1061 int error; 1062 size_t length; 1063 1064 error = 0; 1065 1066 bzero(args, sizeof(*args)); 1067 if (argv == NULL) 1068 return (EFAULT); 1069 /* 1070 * Allocate temporary demand zeroed space for argument and 1071 * environment strings: 1072 * 1073 * o ARG_MAX for argument and environment; 1074 * o MAXSHELLCMDLEN for the name of interpreters. 1075 */ 1076 args->buf = (char *) kmem_alloc_wait(exec_map, 1077 PATH_MAX + ARG_MAX + MAXSHELLCMDLEN); 1078 if (args->buf == NULL) 1079 return (ENOMEM); 1080 args->begin_argv = args->buf; 1081 args->endp = args->begin_argv; 1082 args->stringspace = ARG_MAX; 1083 /* 1084 * Copy the file name. 1085 */ 1086 if (fname != NULL) { 1087 args->fname = args->buf + ARG_MAX; 1088 error = (segflg == UIO_SYSSPACE) ? 1089 copystr(fname, args->fname, PATH_MAX, &length) : 1090 copyinstr(fname, args->fname, PATH_MAX, &length); 1091 if (error != 0) 1092 goto err_exit; 1093 } else 1094 args->fname = NULL; 1095 1096 /* 1097 * extract arguments first 1098 */ 1099 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 1100 if (argp == (caddr_t) -1) { 1101 error = EFAULT; 1102 goto err_exit; 1103 } 1104 if ((error = copyinstr(argp, args->endp, 1105 args->stringspace, &length))) { 1106 if (error == ENAMETOOLONG) 1107 error = E2BIG; 1108 goto err_exit; 1109 } 1110 args->stringspace -= length; 1111 args->endp += length; 1112 args->argc++; 1113 } 1114 1115 args->begin_envv = args->endp; 1116 1117 /* 1118 * extract environment strings 1119 */ 1120 if (envv) { 1121 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) { 1122 if (envp == (caddr_t)-1) { 1123 error = EFAULT; 1124 goto err_exit; 1125 } 1126 if ((error = copyinstr(envp, args->endp, 1127 args->stringspace, &length))) { 1128 if (error == ENAMETOOLONG) 1129 error = E2BIG; 1130 goto err_exit; 1131 } 1132 args->stringspace -= length; 1133 args->endp += length; 1134 args->envc++; 1135 } 1136 } 1137 1138 return (0); 1139 1140 err_exit: 1141 exec_free_args(args); 1142 return (error); 1143 } 1144 1145 static void 1146 exec_free_args(struct image_args *args) 1147 { 1148 1149 if (args->buf) { 1150 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf, 1151 PATH_MAX + ARG_MAX + MAXSHELLCMDLEN); 1152 args->buf = NULL; 1153 } 1154 } 1155 1156 /* 1157 * Copy strings out to the new process address space, constructing new arg 1158 * and env vector tables. Return a pointer to the base so that it can be used 1159 * as the initial stack pointer. 1160 */ 1161 register_t * 1162 exec_copyout_strings(imgp) 1163 struct image_params *imgp; 1164 { 1165 int argc, envc; 1166 char **vectp; 1167 char *stringp, *destp; 1168 register_t *stack_base; 1169 struct ps_strings *arginfo; 1170 struct proc *p; 1171 int szsigcode; 1172 1173 /* 1174 * Calculate string base and vector table pointers. 1175 * Also deal with signal trampoline code for this exec type. 1176 */ 1177 p = imgp->proc; 1178 szsigcode = 0; 1179 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1180 if (p->p_sysent->sv_szsigcode != NULL) 1181 szsigcode = *(p->p_sysent->sv_szsigcode); 1182 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 1183 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *)); 1184 1185 /* 1186 * install sigcode 1187 */ 1188 if (szsigcode) 1189 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo - 1190 szsigcode), szsigcode); 1191 1192 /* 1193 * If we have a valid auxargs ptr, prepare some room 1194 * on the stack. 1195 */ 1196 if (imgp->auxargs) { 1197 /* 1198 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1199 * lower compatibility. 1200 */ 1201 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1202 (AT_COUNT * 2); 1203 /* 1204 * The '+ 2' is for the null pointers at the end of each of 1205 * the arg and env vector sets,and imgp->auxarg_size is room 1206 * for argument of Runtime loader. 1207 */ 1208 vectp = (char **)(destp - (imgp->args->argc + 1209 imgp->args->envc + 2 + imgp->auxarg_size) * 1210 sizeof(char *)); 1211 1212 } else { 1213 /* 1214 * The '+ 2' is for the null pointers at the end of each of 1215 * the arg and env vector sets 1216 */ 1217 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) * 1218 sizeof(char *)); 1219 } 1220 1221 /* 1222 * vectp also becomes our initial stack base 1223 */ 1224 stack_base = (register_t *)vectp; 1225 1226 stringp = imgp->args->begin_argv; 1227 argc = imgp->args->argc; 1228 envc = imgp->args->envc; 1229 1230 /* 1231 * Copy out strings - arguments and environment. 1232 */ 1233 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace); 1234 1235 /* 1236 * Fill in "ps_strings" struct for ps, w, etc. 1237 */ 1238 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1239 suword(&arginfo->ps_nargvstr, argc); 1240 1241 /* 1242 * Fill in argument portion of vector table. 1243 */ 1244 for (; argc > 0; --argc) { 1245 suword(vectp++, (long)(intptr_t)destp); 1246 while (*stringp++ != 0) 1247 destp++; 1248 destp++; 1249 } 1250 1251 /* a null vector table pointer separates the argp's from the envp's */ 1252 suword(vectp++, 0); 1253 1254 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1255 suword(&arginfo->ps_nenvstr, envc); 1256 1257 /* 1258 * Fill in environment portion of vector table. 1259 */ 1260 for (; envc > 0; --envc) { 1261 suword(vectp++, (long)(intptr_t)destp); 1262 while (*stringp++ != 0) 1263 destp++; 1264 destp++; 1265 } 1266 1267 /* end of vector table is a null pointer */ 1268 suword(vectp, 0); 1269 1270 return (stack_base); 1271 } 1272 1273 /* 1274 * Check permissions of file to execute. 1275 * Called with imgp->vp locked. 1276 * Return 0 for success or error code on failure. 1277 */ 1278 int 1279 exec_check_permissions(imgp) 1280 struct image_params *imgp; 1281 { 1282 struct vnode *vp = imgp->vp; 1283 struct vattr *attr = imgp->attr; 1284 struct thread *td; 1285 int error; 1286 1287 td = curthread; 1288 1289 /* Get file attributes */ 1290 error = VOP_GETATTR(vp, attr, td->td_ucred, td); 1291 if (error) 1292 return (error); 1293 1294 #ifdef MAC 1295 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1296 if (error) 1297 return (error); 1298 #endif 1299 1300 /* 1301 * 1) Check if file execution is disabled for the filesystem that this 1302 * file resides on. 1303 * 2) Insure that at least one execute bit is on - otherwise root 1304 * will always succeed, and we don't want to happen unless the 1305 * file really is executable. 1306 * 3) Insure that the file is a regular file. 1307 */ 1308 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1309 ((attr->va_mode & 0111) == 0) || 1310 (attr->va_type != VREG)) 1311 return (EACCES); 1312 1313 /* 1314 * Zero length files can't be exec'd 1315 */ 1316 if (attr->va_size == 0) 1317 return (ENOEXEC); 1318 1319 /* 1320 * Check for execute permission to file based on current credentials. 1321 */ 1322 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1323 if (error) 1324 return (error); 1325 1326 /* 1327 * Check number of open-for-writes on the file and deny execution 1328 * if there are any. 1329 */ 1330 if (vp->v_writecount) 1331 return (ETXTBSY); 1332 1333 /* 1334 * Call filesystem specific open routine (which does nothing in the 1335 * general case). 1336 */ 1337 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1338 if (error == 0) 1339 imgp->opened = 1; 1340 return (error); 1341 } 1342 1343 /* 1344 * Exec handler registration 1345 */ 1346 int 1347 exec_register(execsw_arg) 1348 const struct execsw *execsw_arg; 1349 { 1350 const struct execsw **es, **xs, **newexecsw; 1351 int count = 2; /* New slot and trailing NULL */ 1352 1353 if (execsw) 1354 for (es = execsw; *es; es++) 1355 count++; 1356 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1357 if (newexecsw == NULL) 1358 return (ENOMEM); 1359 xs = newexecsw; 1360 if (execsw) 1361 for (es = execsw; *es; es++) 1362 *xs++ = *es; 1363 *xs++ = execsw_arg; 1364 *xs = NULL; 1365 if (execsw) 1366 free(execsw, M_TEMP); 1367 execsw = newexecsw; 1368 return (0); 1369 } 1370 1371 int 1372 exec_unregister(execsw_arg) 1373 const struct execsw *execsw_arg; 1374 { 1375 const struct execsw **es, **xs, **newexecsw; 1376 int count = 1; 1377 1378 if (execsw == NULL) 1379 panic("unregister with no handlers left?\n"); 1380 1381 for (es = execsw; *es; es++) { 1382 if (*es == execsw_arg) 1383 break; 1384 } 1385 if (*es == NULL) 1386 return (ENOENT); 1387 for (es = execsw; *es; es++) 1388 if (*es != execsw_arg) 1389 count++; 1390 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1391 if (newexecsw == NULL) 1392 return (ENOMEM); 1393 xs = newexecsw; 1394 for (es = execsw; *es; es++) 1395 if (*es != execsw_arg) 1396 *xs++ = *es; 1397 *xs = NULL; 1398 if (execsw) 1399 free(execsw, M_TEMP); 1400 execsw = newexecsw; 1401 return (0); 1402 } 1403