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 #include <sys/stat.h> 66 #ifdef KTRACE 67 #include <sys/ktrace.h> 68 #endif 69 70 #include <vm/vm.h> 71 #include <vm/vm_param.h> 72 #include <vm/pmap.h> 73 #include <vm/vm_page.h> 74 #include <vm/vm_map.h> 75 #include <vm/vm_kern.h> 76 #include <vm/vm_extern.h> 77 #include <vm/vm_object.h> 78 #include <vm/vm_pager.h> 79 80 #ifdef HWPMC_HOOKS 81 #include <sys/pmckern.h> 82 #endif 83 84 #include <machine/reg.h> 85 86 #include <security/audit/audit.h> 87 #include <security/mac/mac_framework.h> 88 89 #ifdef KDTRACE_HOOKS 90 #include <sys/dtrace_bsd.h> 91 dtrace_execexit_func_t dtrace_fasttrap_exec; 92 #endif 93 94 SDT_PROVIDER_DECLARE(proc); 95 SDT_PROBE_DEFINE(proc, kernel, , exec); 96 SDT_PROBE_ARGTYPE(proc, kernel, , exec, 0, "char *"); 97 SDT_PROBE_DEFINE(proc, kernel, , exec_failure); 98 SDT_PROBE_ARGTYPE(proc, kernel, , exec_failure, 0, "int"); 99 SDT_PROBE_DEFINE(proc, kernel, , exec_success); 100 SDT_PROBE_ARGTYPE(proc, kernel, , exec_success, 0, "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 static void exec_free_args(struct image_args *); 110 111 /* XXX This should be vm_size_t. */ 112 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD, 113 NULL, 0, sysctl_kern_ps_strings, "LU", ""); 114 115 /* XXX This should be vm_size_t. */ 116 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD, 117 NULL, 0, sysctl_kern_usrstack, "LU", ""); 118 119 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 120 NULL, 0, sysctl_kern_stackprot, "I", ""); 121 122 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 123 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 124 &ps_arg_cache_limit, 0, ""); 125 126 static int 127 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 128 { 129 struct proc *p; 130 int error; 131 132 p = curproc; 133 #ifdef SCTL_MASK32 134 if (req->flags & SCTL_MASK32) { 135 unsigned int val; 136 val = (unsigned int)p->p_sysent->sv_psstrings; 137 error = SYSCTL_OUT(req, &val, sizeof(val)); 138 } else 139 #endif 140 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 141 sizeof(p->p_sysent->sv_psstrings)); 142 return error; 143 } 144 145 static int 146 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 147 { 148 struct proc *p; 149 int error; 150 151 p = curproc; 152 #ifdef SCTL_MASK32 153 if (req->flags & SCTL_MASK32) { 154 unsigned int val; 155 val = (unsigned int)p->p_sysent->sv_usrstack; 156 error = SYSCTL_OUT(req, &val, sizeof(val)); 157 } else 158 #endif 159 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 160 sizeof(p->p_sysent->sv_usrstack)); 161 return error; 162 } 163 164 static int 165 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 166 { 167 struct proc *p; 168 169 p = curproc; 170 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 171 sizeof(p->p_sysent->sv_stackprot))); 172 } 173 174 /* 175 * Each of the items is a pointer to a `const struct execsw', hence the 176 * double pointer here. 177 */ 178 static const struct execsw **execsw; 179 180 #ifndef _SYS_SYSPROTO_H_ 181 struct execve_args { 182 char *fname; 183 char **argv; 184 char **envv; 185 }; 186 #endif 187 188 int 189 execve(td, uap) 190 struct thread *td; 191 struct execve_args /* { 192 char *fname; 193 char **argv; 194 char **envv; 195 } */ *uap; 196 { 197 int error; 198 struct image_args args; 199 200 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 201 uap->argv, uap->envv); 202 if (error == 0) 203 error = kern_execve(td, &args, NULL); 204 return (error); 205 } 206 207 #ifndef _SYS_SYSPROTO_H_ 208 struct fexecve_args { 209 int fd; 210 char **argv; 211 char **envv; 212 } 213 #endif 214 int 215 fexecve(struct thread *td, struct fexecve_args *uap) 216 { 217 int error; 218 struct image_args args; 219 220 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 221 uap->argv, uap->envv); 222 if (error == 0) { 223 args.fd = uap->fd; 224 error = kern_execve(td, &args, NULL); 225 } 226 return (error); 227 } 228 229 #ifndef _SYS_SYSPROTO_H_ 230 struct __mac_execve_args { 231 char *fname; 232 char **argv; 233 char **envv; 234 struct mac *mac_p; 235 }; 236 #endif 237 238 int 239 __mac_execve(td, uap) 240 struct thread *td; 241 struct __mac_execve_args /* { 242 char *fname; 243 char **argv; 244 char **envv; 245 struct mac *mac_p; 246 } */ *uap; 247 { 248 #ifdef MAC 249 int error; 250 struct image_args args; 251 252 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 253 uap->argv, uap->envv); 254 if (error == 0) 255 error = kern_execve(td, &args, uap->mac_p); 256 return (error); 257 #else 258 return (ENOSYS); 259 #endif 260 } 261 262 /* 263 * XXX: kern_execve has the astonishing property of not always returning to 264 * the caller. If sufficiently bad things happen during the call to 265 * do_execve(), it can end up calling exit1(); as a result, callers must 266 * avoid doing anything which they might need to undo (e.g., allocating 267 * memory). 268 */ 269 int 270 kern_execve(td, args, mac_p) 271 struct thread *td; 272 struct image_args *args; 273 struct mac *mac_p; 274 { 275 struct proc *p = td->td_proc; 276 int error; 277 278 AUDIT_ARG(argv, args->begin_argv, args->argc, 279 args->begin_envv - args->begin_argv); 280 AUDIT_ARG(envv, args->begin_envv, args->envc, 281 args->endp - args->begin_envv); 282 if (p->p_flag & P_HADTHREADS) { 283 PROC_LOCK(p); 284 if (thread_single(SINGLE_BOUNDARY)) { 285 PROC_UNLOCK(p); 286 exec_free_args(args); 287 return (ERESTART); /* Try again later. */ 288 } 289 PROC_UNLOCK(p); 290 } 291 292 error = do_execve(td, args, mac_p); 293 294 if (p->p_flag & P_HADTHREADS) { 295 PROC_LOCK(p); 296 /* 297 * If success, we upgrade to SINGLE_EXIT state to 298 * force other threads to suicide. 299 */ 300 if (error == 0) 301 thread_single(SINGLE_EXIT); 302 else 303 thread_single_end(); 304 PROC_UNLOCK(p); 305 } 306 307 return (error); 308 } 309 310 /* 311 * In-kernel implementation of execve(). All arguments are assumed to be 312 * userspace pointers from the passed thread. 313 */ 314 static int 315 do_execve(td, args, mac_p) 316 struct thread *td; 317 struct image_args *args; 318 struct mac *mac_p; 319 { 320 struct proc *p = td->td_proc; 321 struct nameidata nd, *ndp; 322 struct ucred *newcred = NULL, *oldcred; 323 struct uidinfo *euip; 324 register_t *stack_base; 325 int error, len = 0, i; 326 struct image_params image_params, *imgp; 327 struct vattr attr; 328 int (*img_first)(struct image_params *); 329 struct pargs *oldargs = NULL, *newargs = NULL; 330 struct sigacts *oldsigacts, *newsigacts; 331 #ifdef KTRACE 332 struct vnode *tracevp = NULL; 333 struct ucred *tracecred = NULL; 334 #endif 335 struct vnode *textvp = NULL, *binvp = NULL; 336 int credential_changing; 337 int vfslocked; 338 int textset; 339 #ifdef MAC 340 struct label *interpvplabel = NULL; 341 int will_transition; 342 #endif 343 #ifdef HWPMC_HOOKS 344 struct pmckern_procexec pe; 345 #endif 346 static const char fexecv_proc_title[] = "(fexecv)"; 347 348 vfslocked = 0; 349 imgp = &image_params; 350 351 /* 352 * Lock the process and set the P_INEXEC flag to indicate that 353 * it should be left alone until we're done here. This is 354 * necessary to avoid race conditions - e.g. in ptrace() - 355 * that might allow a local user to illicitly obtain elevated 356 * privileges. 357 */ 358 PROC_LOCK(p); 359 KASSERT((p->p_flag & P_INEXEC) == 0, 360 ("%s(): process already has P_INEXEC flag", __func__)); 361 p->p_flag |= P_INEXEC; 362 PROC_UNLOCK(p); 363 364 /* 365 * Initialize part of the common data 366 */ 367 imgp->proc = p; 368 imgp->execlabel = NULL; 369 imgp->attr = &attr; 370 imgp->entry_addr = 0; 371 imgp->vmspace_destroyed = 0; 372 imgp->interpreted = 0; 373 imgp->opened = 0; 374 imgp->interpreter_name = args->buf + PATH_MAX + ARG_MAX; 375 imgp->auxargs = NULL; 376 imgp->vp = NULL; 377 imgp->object = NULL; 378 imgp->firstpage = NULL; 379 imgp->ps_strings = 0; 380 imgp->auxarg_size = 0; 381 imgp->args = args; 382 383 #ifdef MAC 384 error = mac_execve_enter(imgp, mac_p); 385 if (error) 386 goto exec_fail; 387 #endif 388 389 imgp->image_header = NULL; 390 391 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 392 393 /* 394 * Translate the file name. namei() returns a vnode pointer 395 * in ni_vp amoung other things. 396 * 397 * XXXAUDIT: It would be desirable to also audit the name of the 398 * interpreter if this is an interpreted binary. 399 */ 400 if (args->fname != NULL) { 401 ndp = &nd; 402 NDINIT(ndp, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 403 | MPSAFE | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 404 } 405 406 interpret: 407 if (args->fname != NULL) { 408 error = namei(ndp); 409 if (error) 410 goto exec_fail; 411 412 vfslocked = NDHASGIANT(ndp); 413 binvp = ndp->ni_vp; 414 imgp->vp = binvp; 415 } else { 416 AUDIT_ARG(fd, args->fd); 417 error = fgetvp(td, args->fd, &binvp); 418 if (error) 419 goto exec_fail; 420 vfslocked = VFS_LOCK_GIANT(binvp->v_mount); 421 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY); 422 AUDIT_ARG(vnode, binvp, ARG_VNODE1); 423 imgp->vp = binvp; 424 } 425 426 /* 427 * Check file permissions (also 'opens' file) 428 */ 429 error = exec_check_permissions(imgp); 430 if (error) 431 goto exec_fail_dealloc; 432 433 imgp->object = imgp->vp->v_object; 434 if (imgp->object != NULL) 435 vm_object_reference(imgp->object); 436 437 /* 438 * Set VV_TEXT now so no one can write to the executable while we're 439 * activating it. 440 * 441 * Remember if this was set before and unset it in case this is not 442 * actually an executable image. 443 */ 444 textset = imgp->vp->v_vflag & VV_TEXT; 445 imgp->vp->v_vflag |= VV_TEXT; 446 447 error = exec_map_first_page(imgp); 448 if (error) 449 goto exec_fail_dealloc; 450 451 imgp->proc->p_osrel = 0; 452 /* 453 * If the current process has a special image activator it 454 * wants to try first, call it. For example, emulating shell 455 * scripts differently. 456 */ 457 error = -1; 458 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 459 error = img_first(imgp); 460 461 /* 462 * Loop through the list of image activators, calling each one. 463 * An activator returns -1 if there is no match, 0 on success, 464 * and an error otherwise. 465 */ 466 for (i = 0; error == -1 && execsw[i]; ++i) { 467 if (execsw[i]->ex_imgact == NULL || 468 execsw[i]->ex_imgact == img_first) { 469 continue; 470 } 471 error = (*execsw[i]->ex_imgact)(imgp); 472 } 473 474 if (error) { 475 if (error == -1) { 476 if (textset == 0) 477 imgp->vp->v_vflag &= ~VV_TEXT; 478 error = ENOEXEC; 479 } 480 goto exec_fail_dealloc; 481 } 482 483 /* 484 * Special interpreter operation, cleanup and loop up to try to 485 * activate the interpreter. 486 */ 487 if (imgp->interpreted) { 488 exec_unmap_first_page(imgp); 489 /* 490 * VV_TEXT needs to be unset for scripts. There is a short 491 * period before we determine that something is a script where 492 * VV_TEXT will be set. The vnode lock is held over this 493 * entire period so nothing should illegitimately be blocked. 494 */ 495 imgp->vp->v_vflag &= ~VV_TEXT; 496 /* free name buffer and old vnode */ 497 if (args->fname != NULL) 498 NDFREE(ndp, NDF_ONLY_PNBUF); 499 #ifdef MAC 500 mac_execve_interpreter_enter(binvp, &interpvplabel); 501 #endif 502 if (imgp->opened) { 503 VOP_CLOSE(binvp, FREAD, td->td_ucred, td); 504 imgp->opened = 0; 505 } 506 vput(binvp); 507 vm_object_deallocate(imgp->object); 508 imgp->object = NULL; 509 VFS_UNLOCK_GIANT(vfslocked); 510 vfslocked = 0; 511 /* set new name to that of the interpreter */ 512 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME | MPSAFE, 513 UIO_SYSSPACE, imgp->interpreter_name, td); 514 args->fname = imgp->interpreter_name; 515 goto interpret; 516 } 517 518 /* 519 * NB: We unlock the vnode here because it is believed that none 520 * of the sv_copyout_strings/sv_fixup operations require the vnode. 521 */ 522 VOP_UNLOCK(imgp->vp, 0); 523 /* 524 * Copy out strings (args and env) and initialize stack base 525 */ 526 if (p->p_sysent->sv_copyout_strings) 527 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 528 else 529 stack_base = exec_copyout_strings(imgp); 530 531 /* 532 * If custom stack fixup routine present for this process 533 * let it do the stack setup. 534 * Else stuff argument count as first item on stack 535 */ 536 if (p->p_sysent->sv_fixup != NULL) 537 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 538 else 539 suword(--stack_base, imgp->args->argc); 540 541 /* 542 * For security and other reasons, the file descriptor table cannot 543 * be shared after an exec. 544 */ 545 fdunshare(p, td); 546 547 /* 548 * Malloc things before we need locks. 549 */ 550 newcred = crget(); 551 euip = uifind(attr.va_uid); 552 i = imgp->args->begin_envv - imgp->args->begin_argv; 553 /* Cache arguments if they fit inside our allowance */ 554 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 555 newargs = pargs_alloc(i); 556 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 557 } 558 559 /* close files on exec */ 560 fdcloseexec(td); 561 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 562 563 /* Get a reference to the vnode prior to locking the proc */ 564 VREF(binvp); 565 566 /* 567 * For security and other reasons, signal handlers cannot 568 * be shared after an exec. The new process gets a copy of the old 569 * handlers. In execsigs(), the new process will have its signals 570 * reset. 571 */ 572 PROC_LOCK(p); 573 if (sigacts_shared(p->p_sigacts)) { 574 oldsigacts = p->p_sigacts; 575 PROC_UNLOCK(p); 576 newsigacts = sigacts_alloc(); 577 sigacts_copy(newsigacts, oldsigacts); 578 PROC_LOCK(p); 579 p->p_sigacts = newsigacts; 580 } else 581 oldsigacts = NULL; 582 583 /* Stop profiling */ 584 stopprofclock(p); 585 586 /* reset caught signals */ 587 execsigs(p); 588 589 /* name this process - nameiexec(p, ndp) */ 590 if (args->fname) { 591 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 592 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 593 } else { 594 len = MAXCOMLEN; 595 if (vn_commname(binvp, p->p_comm, MAXCOMLEN + 1) == 0) 596 len = MAXCOMLEN; 597 else { 598 len = sizeof(fexecv_proc_title); 599 bcopy(fexecv_proc_title, p->p_comm, len); 600 } 601 } 602 p->p_comm[len] = 0; 603 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 604 605 /* 606 * mark as execed, wakeup the process that vforked (if any) and tell 607 * it that it now has its own resources back 608 */ 609 p->p_flag |= P_EXEC; 610 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 611 p->p_flag &= ~P_PPWAIT; 612 wakeup(p->p_pptr); 613 } 614 615 /* 616 * Implement image setuid/setgid. 617 * 618 * Don't honor setuid/setgid if the filesystem prohibits it or if 619 * the process is being traced. 620 * 621 * XXXMAC: For the time being, use NOSUID to also prohibit 622 * transitions on the file system. 623 */ 624 oldcred = p->p_ucred; 625 credential_changing = 0; 626 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 627 attr.va_uid; 628 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 629 attr.va_gid; 630 #ifdef MAC 631 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 632 interpvplabel, imgp); 633 credential_changing |= will_transition; 634 #endif 635 636 if (credential_changing && 637 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 638 (p->p_flag & P_TRACED) == 0) { 639 /* 640 * Turn off syscall tracing for set-id programs, except for 641 * root. Record any set-id flags first to make sure that 642 * we do not regain any tracing during a possible block. 643 */ 644 setsugid(p); 645 646 #ifdef KTRACE 647 if (p->p_tracevp != NULL && 648 priv_check_cred(oldcred, PRIV_DEBUG_DIFFCRED, 0)) { 649 mtx_lock(&ktrace_mtx); 650 p->p_traceflag = 0; 651 tracevp = p->p_tracevp; 652 p->p_tracevp = NULL; 653 tracecred = p->p_tracecred; 654 p->p_tracecred = NULL; 655 mtx_unlock(&ktrace_mtx); 656 } 657 #endif 658 /* 659 * Close any file descriptors 0..2 that reference procfs, 660 * then make sure file descriptors 0..2 are in use. 661 * 662 * setugidsafety() may call closef() and then pfind() 663 * which may grab the process lock. 664 * fdcheckstd() may call falloc() which may block to 665 * allocate memory, so temporarily drop the process lock. 666 */ 667 PROC_UNLOCK(p); 668 setugidsafety(td); 669 VOP_UNLOCK(imgp->vp, 0); 670 error = fdcheckstd(td); 671 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 672 if (error != 0) 673 goto done1; 674 PROC_LOCK(p); 675 /* 676 * Set the new credentials. 677 */ 678 crcopy(newcred, oldcred); 679 if (attr.va_mode & S_ISUID) 680 change_euid(newcred, euip); 681 if (attr.va_mode & S_ISGID) 682 change_egid(newcred, attr.va_gid); 683 #ifdef MAC 684 if (will_transition) { 685 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 686 interpvplabel, imgp); 687 } 688 #endif 689 /* 690 * Implement correct POSIX saved-id behavior. 691 * 692 * XXXMAC: Note that the current logic will save the 693 * uid and gid if a MAC domain transition occurs, even 694 * though maybe it shouldn't. 695 */ 696 change_svuid(newcred, newcred->cr_uid); 697 change_svgid(newcred, newcred->cr_gid); 698 p->p_ucred = newcred; 699 newcred = NULL; 700 } else { 701 if (oldcred->cr_uid == oldcred->cr_ruid && 702 oldcred->cr_gid == oldcred->cr_rgid) 703 p->p_flag &= ~P_SUGID; 704 /* 705 * Implement correct POSIX saved-id behavior. 706 * 707 * XXX: It's not clear that the existing behavior is 708 * POSIX-compliant. A number of sources indicate that the 709 * saved uid/gid should only be updated if the new ruid is 710 * not equal to the old ruid, or the new euid is not equal 711 * to the old euid and the new euid is not equal to the old 712 * ruid. The FreeBSD code always updates the saved uid/gid. 713 * Also, this code uses the new (replaced) euid and egid as 714 * the source, which may or may not be the right ones to use. 715 */ 716 if (oldcred->cr_svuid != oldcred->cr_uid || 717 oldcred->cr_svgid != oldcred->cr_gid) { 718 crcopy(newcred, oldcred); 719 change_svuid(newcred, newcred->cr_uid); 720 change_svgid(newcred, newcred->cr_gid); 721 p->p_ucred = newcred; 722 newcred = NULL; 723 } 724 } 725 726 /* 727 * Store the vp for use in procfs. This vnode was referenced prior 728 * to locking the proc lock. 729 */ 730 textvp = p->p_textvp; 731 p->p_textvp = binvp; 732 733 #ifdef KDTRACE_HOOKS 734 /* 735 * Tell the DTrace fasttrap provider about the exec if it 736 * has declared an interest. 737 */ 738 if (dtrace_fasttrap_exec) 739 dtrace_fasttrap_exec(p); 740 #endif 741 742 /* 743 * Notify others that we exec'd, and clear the P_INEXEC flag 744 * as we're now a bona fide freshly-execed process. 745 */ 746 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 747 p->p_flag &= ~P_INEXEC; 748 749 /* 750 * If tracing the process, trap to debugger so breakpoints 751 * can be set before the program executes. 752 * Use tdsignal to deliver signal to current thread, use 753 * psignal may cause the signal to be delivered to wrong thread 754 * because that thread will exit, remember we are going to enter 755 * single thread mode. 756 */ 757 if (p->p_flag & P_TRACED) 758 tdsignal(p, td, SIGTRAP, NULL); 759 760 /* clear "fork but no exec" flag, as we _are_ execing */ 761 p->p_acflag &= ~AFORK; 762 763 /* 764 * Free any previous argument cache and replace it with 765 * the new argument cache, if any. 766 */ 767 oldargs = p->p_args; 768 p->p_args = newargs; 769 newargs = NULL; 770 771 #ifdef HWPMC_HOOKS 772 /* 773 * Check if system-wide sampling is in effect or if the 774 * current process is using PMCs. If so, do exec() time 775 * processing. This processing needs to happen AFTER the 776 * P_INEXEC flag is cleared. 777 * 778 * The proc lock needs to be released before taking the PMC 779 * SX. 780 */ 781 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 782 PROC_UNLOCK(p); 783 pe.pm_credentialschanged = credential_changing; 784 pe.pm_entryaddr = imgp->entry_addr; 785 786 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 787 } else 788 PROC_UNLOCK(p); 789 #else /* !HWPMC_HOOKS */ 790 PROC_UNLOCK(p); 791 #endif 792 793 /* Set values passed into the program in registers. */ 794 if (p->p_sysent->sv_setregs) 795 (*p->p_sysent->sv_setregs)(td, imgp->entry_addr, 796 (u_long)(uintptr_t)stack_base, imgp->ps_strings); 797 else 798 exec_setregs(td, imgp->entry_addr, 799 (u_long)(uintptr_t)stack_base, imgp->ps_strings); 800 801 vfs_mark_atime(imgp->vp, td->td_ucred); 802 803 done1: 804 805 /* 806 * Free any resources malloc'd earlier that we didn't use. 807 */ 808 uifree(euip); 809 if (newcred == NULL) 810 crfree(oldcred); 811 else 812 crfree(newcred); 813 VOP_UNLOCK(imgp->vp, 0); 814 815 SDT_PROBE(proc, kernel, , exec_success, args->fname, 0, 0, 0, 0); 816 817 /* 818 * Handle deferred decrement of ref counts. 819 */ 820 if (textvp != NULL) { 821 int tvfslocked; 822 823 tvfslocked = VFS_LOCK_GIANT(textvp->v_mount); 824 vrele(textvp); 825 VFS_UNLOCK_GIANT(tvfslocked); 826 } 827 if (binvp && error != 0) 828 vrele(binvp); 829 #ifdef KTRACE 830 if (tracevp != NULL) { 831 int tvfslocked; 832 833 tvfslocked = VFS_LOCK_GIANT(tracevp->v_mount); 834 vrele(tracevp); 835 VFS_UNLOCK_GIANT(tvfslocked); 836 } 837 if (tracecred != NULL) 838 crfree(tracecred); 839 #endif 840 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 841 pargs_drop(oldargs); 842 pargs_drop(newargs); 843 if (oldsigacts != NULL) 844 sigacts_free(oldsigacts); 845 846 exec_fail_dealloc: 847 848 /* 849 * free various allocated resources 850 */ 851 if (imgp->firstpage != NULL) 852 exec_unmap_first_page(imgp); 853 854 if (imgp->vp != NULL) { 855 if (args->fname) 856 NDFREE(ndp, NDF_ONLY_PNBUF); 857 if (imgp->opened) 858 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 859 vput(imgp->vp); 860 } 861 862 if (imgp->object != NULL) 863 vm_object_deallocate(imgp->object); 864 865 if (error == 0) { 866 /* 867 * Stop the process here if its stop event mask has 868 * the S_EXEC bit set. 869 */ 870 STOPEVENT(p, S_EXEC, 0); 871 goto done2; 872 } 873 874 exec_fail: 875 /* we're done here, clear P_INEXEC */ 876 PROC_LOCK(p); 877 p->p_flag &= ~P_INEXEC; 878 PROC_UNLOCK(p); 879 880 SDT_PROBE(proc, kernel, , exec_failure, error, 0, 0, 0, 0); 881 882 done2: 883 #ifdef MAC 884 mac_execve_exit(imgp); 885 mac_execve_interpreter_exit(interpvplabel); 886 #endif 887 VFS_UNLOCK_GIANT(vfslocked); 888 exec_free_args(args); 889 890 if (error && imgp->vmspace_destroyed) { 891 /* sorry, no more process anymore. exit gracefully */ 892 exit1(td, W_EXITCODE(0, SIGABRT)); 893 /* NOT REACHED */ 894 } 895 return (error); 896 } 897 898 int 899 exec_map_first_page(imgp) 900 struct image_params *imgp; 901 { 902 int rv, i; 903 int initial_pagein; 904 vm_page_t ma[VM_INITIAL_PAGEIN]; 905 vm_object_t object; 906 907 if (imgp->firstpage != NULL) 908 exec_unmap_first_page(imgp); 909 910 object = imgp->vp->v_object; 911 if (object == NULL) 912 return (EACCES); 913 VM_OBJECT_LOCK(object); 914 #if VM_NRESERVLEVEL > 0 915 if ((object->flags & OBJ_COLORED) == 0) { 916 object->flags |= OBJ_COLORED; 917 object->pg_color = 0; 918 } 919 #endif 920 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 921 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 922 initial_pagein = VM_INITIAL_PAGEIN; 923 if (initial_pagein > object->size) 924 initial_pagein = object->size; 925 for (i = 1; i < initial_pagein; i++) { 926 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 927 if (ma[i]->valid) 928 break; 929 if ((ma[i]->oflags & VPO_BUSY) || ma[i]->busy) 930 break; 931 vm_page_busy(ma[i]); 932 } else { 933 ma[i] = vm_page_alloc(object, i, 934 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 935 if (ma[i] == NULL) 936 break; 937 } 938 } 939 initial_pagein = i; 940 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 941 ma[0] = vm_page_lookup(object, 0); 942 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || 943 (ma[0]->valid == 0)) { 944 if (ma[0]) { 945 vm_page_lock_queues(); 946 vm_page_free(ma[0]); 947 vm_page_unlock_queues(); 948 } 949 VM_OBJECT_UNLOCK(object); 950 return (EIO); 951 } 952 } 953 vm_page_lock_queues(); 954 vm_page_hold(ma[0]); 955 vm_page_unlock_queues(); 956 vm_page_wakeup(ma[0]); 957 VM_OBJECT_UNLOCK(object); 958 959 imgp->firstpage = sf_buf_alloc(ma[0], 0); 960 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 961 962 return (0); 963 } 964 965 void 966 exec_unmap_first_page(imgp) 967 struct image_params *imgp; 968 { 969 vm_page_t m; 970 971 if (imgp->firstpage != NULL) { 972 m = sf_buf_page(imgp->firstpage); 973 sf_buf_free(imgp->firstpage); 974 imgp->firstpage = NULL; 975 vm_page_lock_queues(); 976 vm_page_unhold(m); 977 vm_page_unlock_queues(); 978 } 979 } 980 981 /* 982 * Destroy old address space, and allocate a new stack 983 * The new stack is only SGROWSIZ large because it is grown 984 * automatically in trap.c. 985 */ 986 int 987 exec_new_vmspace(imgp, sv) 988 struct image_params *imgp; 989 struct sysentvec *sv; 990 { 991 int error; 992 struct proc *p = imgp->proc; 993 struct vmspace *vmspace = p->p_vmspace; 994 vm_offset_t stack_addr; 995 vm_map_t map; 996 u_long ssiz; 997 998 imgp->vmspace_destroyed = 1; 999 imgp->sysent = sv; 1000 1001 /* May be called with Giant held */ 1002 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1003 1004 /* 1005 * Blow away entire process VM, if address space not shared, 1006 * otherwise, create a new VM space so that other threads are 1007 * not disrupted 1008 */ 1009 map = &vmspace->vm_map; 1010 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv->sv_minuser && 1011 vm_map_max(map) == sv->sv_maxuser) { 1012 shmexit(vmspace); 1013 pmap_remove_pages(vmspace_pmap(vmspace)); 1014 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1015 } else { 1016 error = vmspace_exec(p, sv->sv_minuser, sv->sv_maxuser); 1017 if (error) 1018 return (error); 1019 vmspace = p->p_vmspace; 1020 map = &vmspace->vm_map; 1021 } 1022 1023 /* Allocate a new stack */ 1024 if (sv->sv_maxssiz != NULL) 1025 ssiz = *sv->sv_maxssiz; 1026 else 1027 ssiz = maxssiz; 1028 stack_addr = sv->sv_usrstack - ssiz; 1029 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1030 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1031 if (error) 1032 return (error); 1033 1034 #ifdef __ia64__ 1035 /* Allocate a new register stack */ 1036 stack_addr = IA64_BACKINGSTORE; 1037 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1038 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP); 1039 if (error) 1040 return (error); 1041 #endif 1042 1043 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 1044 * VM_STACK case, but they are still used to monitor the size of the 1045 * process stack so we can check the stack rlimit. 1046 */ 1047 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1048 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1049 1050 return (0); 1051 } 1052 1053 /* 1054 * Copy out argument and environment strings from the old process address 1055 * space into the temporary string buffer. 1056 */ 1057 int 1058 exec_copyin_args(struct image_args *args, char *fname, 1059 enum uio_seg segflg, char **argv, char **envv) 1060 { 1061 char *argp, *envp; 1062 int error; 1063 size_t length; 1064 1065 error = 0; 1066 1067 bzero(args, sizeof(*args)); 1068 if (argv == NULL) 1069 return (EFAULT); 1070 /* 1071 * Allocate temporary demand zeroed space for argument and 1072 * environment strings: 1073 * 1074 * o ARG_MAX for argument and environment; 1075 * o MAXSHELLCMDLEN for the name of interpreters. 1076 */ 1077 args->buf = (char *) kmem_alloc_wait(exec_map, 1078 PATH_MAX + ARG_MAX + MAXSHELLCMDLEN); 1079 if (args->buf == NULL) 1080 return (ENOMEM); 1081 args->begin_argv = args->buf; 1082 args->endp = args->begin_argv; 1083 args->stringspace = ARG_MAX; 1084 /* 1085 * Copy the file name. 1086 */ 1087 if (fname != NULL) { 1088 args->fname = args->buf + ARG_MAX; 1089 error = (segflg == UIO_SYSSPACE) ? 1090 copystr(fname, args->fname, PATH_MAX, &length) : 1091 copyinstr(fname, args->fname, PATH_MAX, &length); 1092 if (error != 0) 1093 goto err_exit; 1094 } else 1095 args->fname = NULL; 1096 1097 /* 1098 * extract arguments first 1099 */ 1100 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 1101 if (argp == (caddr_t) -1) { 1102 error = EFAULT; 1103 goto err_exit; 1104 } 1105 if ((error = copyinstr(argp, args->endp, 1106 args->stringspace, &length))) { 1107 if (error == ENAMETOOLONG) 1108 error = E2BIG; 1109 goto err_exit; 1110 } 1111 args->stringspace -= length; 1112 args->endp += length; 1113 args->argc++; 1114 } 1115 1116 args->begin_envv = args->endp; 1117 1118 /* 1119 * extract environment strings 1120 */ 1121 if (envv) { 1122 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) { 1123 if (envp == (caddr_t)-1) { 1124 error = EFAULT; 1125 goto err_exit; 1126 } 1127 if ((error = copyinstr(envp, args->endp, 1128 args->stringspace, &length))) { 1129 if (error == ENAMETOOLONG) 1130 error = E2BIG; 1131 goto err_exit; 1132 } 1133 args->stringspace -= length; 1134 args->endp += length; 1135 args->envc++; 1136 } 1137 } 1138 1139 return (0); 1140 1141 err_exit: 1142 exec_free_args(args); 1143 return (error); 1144 } 1145 1146 static void 1147 exec_free_args(struct image_args *args) 1148 { 1149 1150 if (args->buf) { 1151 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf, 1152 PATH_MAX + ARG_MAX + MAXSHELLCMDLEN); 1153 args->buf = NULL; 1154 } 1155 } 1156 1157 /* 1158 * Copy strings out to the new process address space, constructing new arg 1159 * and env vector tables. Return a pointer to the base so that it can be used 1160 * as the initial stack pointer. 1161 */ 1162 register_t * 1163 exec_copyout_strings(imgp) 1164 struct image_params *imgp; 1165 { 1166 int argc, envc; 1167 char **vectp; 1168 char *stringp, *destp; 1169 register_t *stack_base; 1170 struct ps_strings *arginfo; 1171 struct proc *p; 1172 int szsigcode; 1173 1174 /* 1175 * Calculate string base and vector table pointers. 1176 * Also deal with signal trampoline code for this exec type. 1177 */ 1178 p = imgp->proc; 1179 szsigcode = 0; 1180 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1181 if (p->p_sysent->sv_szsigcode != NULL) 1182 szsigcode = *(p->p_sysent->sv_szsigcode); 1183 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 1184 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *)); 1185 1186 /* 1187 * install sigcode 1188 */ 1189 if (szsigcode) 1190 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo - 1191 szsigcode), szsigcode); 1192 1193 /* 1194 * If we have a valid auxargs ptr, prepare some room 1195 * on the stack. 1196 */ 1197 if (imgp->auxargs) { 1198 /* 1199 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1200 * lower compatibility. 1201 */ 1202 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1203 (AT_COUNT * 2); 1204 /* 1205 * The '+ 2' is for the null pointers at the end of each of 1206 * the arg and env vector sets,and imgp->auxarg_size is room 1207 * for argument of Runtime loader. 1208 */ 1209 vectp = (char **)(destp - (imgp->args->argc + 1210 imgp->args->envc + 2 + imgp->auxarg_size) * 1211 sizeof(char *)); 1212 1213 } else { 1214 /* 1215 * The '+ 2' is for the null pointers at the end of each of 1216 * the arg and env vector sets 1217 */ 1218 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) * 1219 sizeof(char *)); 1220 } 1221 1222 /* 1223 * vectp also becomes our initial stack base 1224 */ 1225 stack_base = (register_t *)vectp; 1226 1227 stringp = imgp->args->begin_argv; 1228 argc = imgp->args->argc; 1229 envc = imgp->args->envc; 1230 1231 /* 1232 * Copy out strings - arguments and environment. 1233 */ 1234 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace); 1235 1236 /* 1237 * Fill in "ps_strings" struct for ps, w, etc. 1238 */ 1239 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1240 suword(&arginfo->ps_nargvstr, argc); 1241 1242 /* 1243 * Fill in argument portion of vector table. 1244 */ 1245 for (; argc > 0; --argc) { 1246 suword(vectp++, (long)(intptr_t)destp); 1247 while (*stringp++ != 0) 1248 destp++; 1249 destp++; 1250 } 1251 1252 /* a null vector table pointer separates the argp's from the envp's */ 1253 suword(vectp++, 0); 1254 1255 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1256 suword(&arginfo->ps_nenvstr, envc); 1257 1258 /* 1259 * Fill in environment portion of vector table. 1260 */ 1261 for (; envc > 0; --envc) { 1262 suword(vectp++, (long)(intptr_t)destp); 1263 while (*stringp++ != 0) 1264 destp++; 1265 destp++; 1266 } 1267 1268 /* end of vector table is a null pointer */ 1269 suword(vectp, 0); 1270 1271 return (stack_base); 1272 } 1273 1274 /* 1275 * Check permissions of file to execute. 1276 * Called with imgp->vp locked. 1277 * Return 0 for success or error code on failure. 1278 */ 1279 int 1280 exec_check_permissions(imgp) 1281 struct image_params *imgp; 1282 { 1283 struct vnode *vp = imgp->vp; 1284 struct vattr *attr = imgp->attr; 1285 struct thread *td; 1286 int error; 1287 1288 td = curthread; 1289 1290 /* Get file attributes */ 1291 error = VOP_GETATTR(vp, attr, td->td_ucred); 1292 if (error) 1293 return (error); 1294 1295 #ifdef MAC 1296 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1297 if (error) 1298 return (error); 1299 #endif 1300 1301 /* 1302 * 1) Check if file execution is disabled for the filesystem that this 1303 * file resides on. 1304 * 2) Insure that at least one execute bit is on - otherwise root 1305 * will always succeed, and we don't want to happen unless the 1306 * file really is executable. 1307 * 3) Insure that the file is a regular file. 1308 */ 1309 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1310 ((attr->va_mode & 0111) == 0) || 1311 (attr->va_type != VREG)) 1312 return (EACCES); 1313 1314 /* 1315 * Zero length files can't be exec'd 1316 */ 1317 if (attr->va_size == 0) 1318 return (ENOEXEC); 1319 1320 /* 1321 * Check for execute permission to file based on current credentials. 1322 */ 1323 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1324 if (error) 1325 return (error); 1326 1327 /* 1328 * Check number of open-for-writes on the file and deny execution 1329 * if there are any. 1330 */ 1331 if (vp->v_writecount) 1332 return (ETXTBSY); 1333 1334 /* 1335 * Call filesystem specific open routine (which does nothing in the 1336 * general case). 1337 */ 1338 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1339 if (error == 0) 1340 imgp->opened = 1; 1341 return (error); 1342 } 1343 1344 /* 1345 * Exec handler registration 1346 */ 1347 int 1348 exec_register(execsw_arg) 1349 const struct execsw *execsw_arg; 1350 { 1351 const struct execsw **es, **xs, **newexecsw; 1352 int count = 2; /* New slot and trailing NULL */ 1353 1354 if (execsw) 1355 for (es = execsw; *es; es++) 1356 count++; 1357 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1358 if (newexecsw == NULL) 1359 return (ENOMEM); 1360 xs = newexecsw; 1361 if (execsw) 1362 for (es = execsw; *es; es++) 1363 *xs++ = *es; 1364 *xs++ = execsw_arg; 1365 *xs = NULL; 1366 if (execsw) 1367 free(execsw, M_TEMP); 1368 execsw = newexecsw; 1369 return (0); 1370 } 1371 1372 int 1373 exec_unregister(execsw_arg) 1374 const struct execsw *execsw_arg; 1375 { 1376 const struct execsw **es, **xs, **newexecsw; 1377 int count = 1; 1378 1379 if (execsw == NULL) 1380 panic("unregister with no handlers left?\n"); 1381 1382 for (es = execsw; *es; es++) { 1383 if (*es == execsw_arg) 1384 break; 1385 } 1386 if (*es == NULL) 1387 return (ENOENT); 1388 for (es = execsw; *es; es++) 1389 if (*es != execsw_arg) 1390 count++; 1391 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1392 if (newexecsw == NULL) 1393 return (ENOMEM); 1394 xs = newexecsw; 1395 for (es = execsw; *es; es++) 1396 if (*es != execsw_arg) 1397 *xs++ = *es; 1398 *xs = NULL; 1399 if (execsw) 1400 free(execsw, M_TEMP); 1401 execsw = newexecsw; 1402 return (0); 1403 } 1404