29 30#include "opt_hwpmc_hooks.h" 31#include "opt_kdtrace.h" 32#include "opt_ktrace.h" 33#include "opt_vm.h" 34 35#include <sys/param.h> 36#include <sys/systm.h> 37#include <sys/eventhandler.h> 38#include <sys/lock.h> 39#include <sys/mutex.h> 40#include <sys/sysproto.h> 41#include <sys/signalvar.h> 42#include <sys/kernel.h> 43#include <sys/mount.h> 44#include <sys/filedesc.h> 45#include <sys/fcntl.h> 46#include <sys/acct.h> 47#include <sys/exec.h> 48#include <sys/imgact.h> 49#include <sys/imgact_elf.h> 50#include <sys/wait.h> 51#include <sys/malloc.h> 52#include <sys/priv.h> 53#include <sys/proc.h> 54#include <sys/pioctl.h> 55#include <sys/namei.h> 56#include <sys/resourcevar.h> 57#include <sys/sdt.h> 58#include <sys/sf_buf.h> 59#include <sys/syscallsubr.h> 60#include <sys/sysent.h> 61#include <sys/shm.h> 62#include <sys/sysctl.h> 63#include <sys/vnode.h> 64#include <sys/stat.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> 90dtrace_execexit_func_t dtrace_fasttrap_exec; 91#endif 92 93SDT_PROVIDER_DECLARE(proc); 94SDT_PROBE_DEFINE(proc, kernel, , exec); 95SDT_PROBE_ARGTYPE(proc, kernel, , exec, 0, "char *"); 96SDT_PROBE_DEFINE(proc, kernel, , exec_failure); 97SDT_PROBE_ARGTYPE(proc, kernel, , exec_failure, 0, "int"); 98SDT_PROBE_DEFINE(proc, kernel, , exec_success); 99SDT_PROBE_ARGTYPE(proc, kernel, , exec_success, 0, "char *"); 100 101MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 102 103static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 104static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 105static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 106static int do_execve(struct thread *td, struct image_args *args, 107 struct mac *mac_p); 108static void exec_free_args(struct image_args *); 109 110/* XXX This should be vm_size_t. */ 111SYSCTL_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. */ 115SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD, 116 NULL, 0, sysctl_kern_usrstack, "LU", ""); 117 118SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 119 NULL, 0, sysctl_kern_stackprot, "I", ""); 120 121u_long ps_arg_cache_limit = PAGE_SIZE / 16; 122SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 123 &ps_arg_cache_limit, 0, ""); 124 125static int map_at_zero = 0; 126TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero); 127SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &map_at_zero, 0, 128 "Permit processes to map an object at virtual address 0."); 129 130static int 131sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 132{ 133 struct proc *p; 134 int error; 135 136 p = curproc; 137#ifdef SCTL_MASK32 138 if (req->flags & SCTL_MASK32) { 139 unsigned int val; 140 val = (unsigned int)p->p_sysent->sv_psstrings; 141 error = SYSCTL_OUT(req, &val, sizeof(val)); 142 } else 143#endif 144 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 145 sizeof(p->p_sysent->sv_psstrings)); 146 return error; 147} 148 149static int 150sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 151{ 152 struct proc *p; 153 int error; 154 155 p = curproc; 156#ifdef SCTL_MASK32 157 if (req->flags & SCTL_MASK32) { 158 unsigned int val; 159 val = (unsigned int)p->p_sysent->sv_usrstack; 160 error = SYSCTL_OUT(req, &val, sizeof(val)); 161 } else 162#endif 163 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 164 sizeof(p->p_sysent->sv_usrstack)); 165 return error; 166} 167 168static int 169sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 170{ 171 struct proc *p; 172 173 p = curproc; 174 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 175 sizeof(p->p_sysent->sv_stackprot))); 176} 177 178/* 179 * Each of the items is a pointer to a `const struct execsw', hence the 180 * double pointer here. 181 */ 182static const struct execsw **execsw; 183 184#ifndef _SYS_SYSPROTO_H_ 185struct execve_args { 186 char *fname; 187 char **argv; 188 char **envv; 189}; 190#endif 191 192int 193execve(td, uap) 194 struct thread *td; 195 struct execve_args /* { 196 char *fname; 197 char **argv; 198 char **envv; 199 } */ *uap; 200{ 201 int error; 202 struct image_args args; 203 204 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 205 uap->argv, uap->envv); 206 if (error == 0) 207 error = kern_execve(td, &args, NULL); 208 return (error); 209} 210 211#ifndef _SYS_SYSPROTO_H_ 212struct fexecve_args { 213 int fd; 214 char **argv; 215 char **envv; 216} 217#endif 218int 219fexecve(struct thread *td, struct fexecve_args *uap) 220{ 221 int error; 222 struct image_args args; 223 224 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 225 uap->argv, uap->envv); 226 if (error == 0) { 227 args.fd = uap->fd; 228 error = kern_execve(td, &args, NULL); 229 } 230 return (error); 231} 232 233#ifndef _SYS_SYSPROTO_H_ 234struct __mac_execve_args { 235 char *fname; 236 char **argv; 237 char **envv; 238 struct mac *mac_p; 239}; 240#endif 241 242int 243__mac_execve(td, uap) 244 struct thread *td; 245 struct __mac_execve_args /* { 246 char *fname; 247 char **argv; 248 char **envv; 249 struct mac *mac_p; 250 } */ *uap; 251{ 252#ifdef MAC 253 int error; 254 struct image_args args; 255 256 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 257 uap->argv, uap->envv); 258 if (error == 0) 259 error = kern_execve(td, &args, uap->mac_p); 260 return (error); 261#else 262 return (ENOSYS); 263#endif 264} 265 266/* 267 * XXX: kern_execve has the astonishing property of not always returning to 268 * the caller. If sufficiently bad things happen during the call to 269 * do_execve(), it can end up calling exit1(); as a result, callers must 270 * avoid doing anything which they might need to undo (e.g., allocating 271 * memory). 272 */ 273int 274kern_execve(td, args, mac_p) 275 struct thread *td; 276 struct image_args *args; 277 struct mac *mac_p; 278{ 279 struct proc *p = td->td_proc; 280 int error; 281 282 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 283 args->begin_envv - args->begin_argv); 284 AUDIT_ARG_ENVV(args->begin_envv, args->envc, 285 args->endp - args->begin_envv); 286 if (p->p_flag & P_HADTHREADS) { 287 PROC_LOCK(p); 288 if (thread_single(SINGLE_BOUNDARY)) { 289 PROC_UNLOCK(p); 290 exec_free_args(args); 291 return (ERESTART); /* Try again later. */ 292 } 293 PROC_UNLOCK(p); 294 } 295 296 error = do_execve(td, args, mac_p); 297 298 if (p->p_flag & P_HADTHREADS) { 299 PROC_LOCK(p); 300 /* 301 * If success, we upgrade to SINGLE_EXIT state to 302 * force other threads to suicide. 303 */ 304 if (error == 0) 305 thread_single(SINGLE_EXIT); 306 else 307 thread_single_end(); 308 PROC_UNLOCK(p); 309 } 310 311 return (error); 312} 313 314/* 315 * In-kernel implementation of execve(). All arguments are assumed to be 316 * userspace pointers from the passed thread. 317 */ 318static int 319do_execve(td, args, mac_p) 320 struct thread *td; 321 struct image_args *args; 322 struct mac *mac_p; 323{ 324 struct proc *p = td->td_proc; 325 struct nameidata nd; 326 struct ucred *newcred = NULL, *oldcred; 327 struct uidinfo *euip; 328 register_t *stack_base; 329 int error, i; 330 struct image_params image_params, *imgp; 331 struct vattr attr; 332 int (*img_first)(struct image_params *); 333 struct pargs *oldargs = NULL, *newargs = NULL; 334 struct sigacts *oldsigacts, *newsigacts; 335#ifdef KTRACE 336 struct vnode *tracevp = NULL; 337 struct ucred *tracecred = NULL; 338#endif 339 struct vnode *textvp = NULL, *binvp = NULL; 340 int credential_changing; 341 int vfslocked; 342 int textset; 343#ifdef MAC 344 struct label *interpvplabel = NULL; 345 int will_transition; 346#endif 347#ifdef HWPMC_HOOKS 348 struct pmckern_procexec pe; 349#endif 350 static const char fexecv_proc_title[] = "(fexecv)"; 351 352 vfslocked = 0; 353 imgp = &image_params; 354 355 /* 356 * Lock the process and set the P_INEXEC flag to indicate that 357 * it should be left alone until we're done here. This is 358 * necessary to avoid race conditions - e.g. in ptrace() - 359 * that might allow a local user to illicitly obtain elevated 360 * privileges. 361 */ 362 PROC_LOCK(p); 363 KASSERT((p->p_flag & P_INEXEC) == 0, 364 ("%s(): process already has P_INEXEC flag", __func__)); 365 p->p_flag |= P_INEXEC; 366 PROC_UNLOCK(p); 367 368 /* 369 * Initialize part of the common data 370 */ 371 imgp->proc = p; 372 imgp->execlabel = NULL; 373 imgp->attr = &attr; 374 imgp->entry_addr = 0; 375 imgp->vmspace_destroyed = 0; 376 imgp->interpreted = 0; 377 imgp->opened = 0; 378 imgp->interpreter_name = args->buf + PATH_MAX + ARG_MAX; 379 imgp->auxargs = NULL; 380 imgp->vp = NULL; 381 imgp->object = NULL; 382 imgp->firstpage = NULL; 383 imgp->ps_strings = 0; 384 imgp->auxarg_size = 0; 385 imgp->args = args; 386 imgp->execpath = imgp->freepath = NULL; 387 imgp->execpathp = 0; 388 389#ifdef MAC 390 error = mac_execve_enter(imgp, mac_p); 391 if (error) 392 goto exec_fail; 393#endif 394 395 imgp->image_header = NULL; 396 397 /* 398 * Translate the file name. namei() returns a vnode pointer 399 * in ni_vp amoung other things. 400 * 401 * XXXAUDIT: It would be desirable to also audit the name of the 402 * interpreter if this is an interpreted binary. 403 */ 404 if (args->fname != NULL) { 405 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 406 | MPSAFE | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 407 } 408 409 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 410 411interpret: 412 if (args->fname != NULL) { 413 error = namei(&nd); 414 if (error) 415 goto exec_fail; 416 417 vfslocked = NDHASGIANT(&nd); 418 binvp = nd.ni_vp; 419 imgp->vp = binvp; 420 } else { 421 AUDIT_ARG_FD(args->fd); 422 error = fgetvp(td, args->fd, &binvp); 423 if (error) 424 goto exec_fail; 425 vfslocked = VFS_LOCK_GIANT(binvp->v_mount); 426 vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY); 427 AUDIT_ARG_VNODE1(binvp); 428 imgp->vp = binvp; 429 } 430 431 /* 432 * Check file permissions (also 'opens' file) 433 */ 434 error = exec_check_permissions(imgp); 435 if (error) 436 goto exec_fail_dealloc; 437 438 imgp->object = imgp->vp->v_object; 439 if (imgp->object != NULL) 440 vm_object_reference(imgp->object); 441 442 /* 443 * Set VV_TEXT now so no one can write to the executable while we're 444 * activating it. 445 * 446 * Remember if this was set before and unset it in case this is not 447 * actually an executable image. 448 */ 449 textset = imgp->vp->v_vflag & VV_TEXT; 450 imgp->vp->v_vflag |= VV_TEXT; 451 452 error = exec_map_first_page(imgp); 453 if (error) 454 goto exec_fail_dealloc; 455 456 imgp->proc->p_osrel = 0; 457 /* 458 * If the current process has a special image activator it 459 * wants to try first, call it. For example, emulating shell 460 * scripts differently. 461 */ 462 error = -1; 463 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 464 error = img_first(imgp); 465 466 /* 467 * Loop through the list of image activators, calling each one. 468 * An activator returns -1 if there is no match, 0 on success, 469 * and an error otherwise. 470 */ 471 for (i = 0; error == -1 && execsw[i]; ++i) { 472 if (execsw[i]->ex_imgact == NULL || 473 execsw[i]->ex_imgact == img_first) { 474 continue; 475 } 476 error = (*execsw[i]->ex_imgact)(imgp); 477 } 478 479 if (error) { 480 if (error == -1) { 481 if (textset == 0) 482 imgp->vp->v_vflag &= ~VV_TEXT; 483 error = ENOEXEC; 484 } 485 goto exec_fail_dealloc; 486 } 487 488 /* 489 * Special interpreter operation, cleanup and loop up to try to 490 * activate the interpreter. 491 */ 492 if (imgp->interpreted) { 493 exec_unmap_first_page(imgp); 494 /* 495 * VV_TEXT needs to be unset for scripts. There is a short 496 * period before we determine that something is a script where 497 * VV_TEXT will be set. The vnode lock is held over this 498 * entire period so nothing should illegitimately be blocked. 499 */ 500 imgp->vp->v_vflag &= ~VV_TEXT; 501 /* free name buffer and old vnode */ 502 if (args->fname != NULL) 503 NDFREE(&nd, NDF_ONLY_PNBUF); 504#ifdef MAC 505 mac_execve_interpreter_enter(binvp, &interpvplabel); 506#endif 507 if (imgp->opened) { 508 VOP_CLOSE(binvp, FREAD, td->td_ucred, td); 509 imgp->opened = 0; 510 } 511 vput(binvp); 512 vm_object_deallocate(imgp->object); 513 imgp->object = NULL; 514 VFS_UNLOCK_GIANT(vfslocked); 515 vfslocked = 0; 516 /* set new name to that of the interpreter */ 517 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME | MPSAFE, 518 UIO_SYSSPACE, imgp->interpreter_name, td); 519 args->fname = imgp->interpreter_name; 520 goto interpret; 521 } 522 523 /* 524 * NB: We unlock the vnode here because it is believed that none 525 * of the sv_copyout_strings/sv_fixup operations require the vnode. 526 */ 527 VOP_UNLOCK(imgp->vp, 0); 528 529 /* 530 * Do the best to calculate the full path to the image file. 531 */ 532 if (imgp->auxargs != NULL && 533 ((args->fname != NULL && args->fname[0] == '/') || 534 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0)) 535 imgp->execpath = args->fname; 536 537 /* 538 * Copy out strings (args and env) and initialize stack base 539 */ 540 if (p->p_sysent->sv_copyout_strings) 541 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 542 else 543 stack_base = exec_copyout_strings(imgp); 544 545 /* 546 * If custom stack fixup routine present for this process 547 * let it do the stack setup. 548 * Else stuff argument count as first item on stack 549 */ 550 if (p->p_sysent->sv_fixup != NULL) 551 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 552 else 553 suword(--stack_base, imgp->args->argc); 554 555 /* 556 * For security and other reasons, the file descriptor table cannot 557 * be shared after an exec. 558 */ 559 fdunshare(p, td); 560 561 /* 562 * Malloc things before we need locks. 563 */ 564 newcred = crget(); 565 euip = uifind(attr.va_uid); 566 i = imgp->args->begin_envv - imgp->args->begin_argv; 567 /* Cache arguments if they fit inside our allowance */ 568 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 569 newargs = pargs_alloc(i); 570 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 571 } 572 573 /* close files on exec */ 574 fdcloseexec(td); 575 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 576 577 /* Get a reference to the vnode prior to locking the proc */ 578 VREF(binvp); 579 580 /* 581 * For security and other reasons, signal handlers cannot 582 * be shared after an exec. The new process gets a copy of the old 583 * handlers. In execsigs(), the new process will have its signals 584 * reset. 585 */ 586 PROC_LOCK(p); 587 oldcred = crcopysafe(p, newcred); 588 if (sigacts_shared(p->p_sigacts)) { 589 oldsigacts = p->p_sigacts; 590 PROC_UNLOCK(p); 591 newsigacts = sigacts_alloc(); 592 sigacts_copy(newsigacts, oldsigacts); 593 PROC_LOCK(p); 594 p->p_sigacts = newsigacts; 595 } else 596 oldsigacts = NULL; 597 598 /* Stop profiling */ 599 stopprofclock(p); 600 601 /* reset caught signals */ 602 execsigs(p); 603 604 /* name this process - nameiexec(p, ndp) */ 605 bzero(p->p_comm, sizeof(p->p_comm)); 606 if (args->fname) 607 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 608 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 609 else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0) 610 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 611 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 612 613 /* 614 * mark as execed, wakeup the process that vforked (if any) and tell 615 * it that it now has its own resources back 616 */ 617 p->p_flag |= P_EXEC; 618 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 619 p->p_flag &= ~P_PPWAIT; 620 cv_broadcast(&p->p_pwait); 621 } 622 623 /* 624 * Implement image setuid/setgid. 625 * 626 * Don't honor setuid/setgid if the filesystem prohibits it or if 627 * the process is being traced. 628 * 629 * XXXMAC: For the time being, use NOSUID to also prohibit 630 * transitions on the file system. 631 */ 632 credential_changing = 0; 633 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 634 attr.va_uid; 635 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 636 attr.va_gid; 637#ifdef MAC 638 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 639 interpvplabel, imgp); 640 credential_changing |= will_transition; 641#endif 642 643 if (credential_changing && 644 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 645 (p->p_flag & P_TRACED) == 0) { 646 /* 647 * Turn off syscall tracing for set-id programs, except for 648 * root. Record any set-id flags first to make sure that 649 * we do not regain any tracing during a possible block. 650 */ 651 setsugid(p); 652 653#ifdef KTRACE 654 if (p->p_tracevp != NULL && 655 priv_check_cred(oldcred, PRIV_DEBUG_DIFFCRED, 0)) { 656 mtx_lock(&ktrace_mtx); 657 p->p_traceflag = 0; 658 tracevp = p->p_tracevp; 659 p->p_tracevp = NULL; 660 tracecred = p->p_tracecred; 661 p->p_tracecred = NULL; 662 mtx_unlock(&ktrace_mtx); 663 } 664#endif 665 /* 666 * Close any file descriptors 0..2 that reference procfs, 667 * then make sure file descriptors 0..2 are in use. 668 * 669 * setugidsafety() may call closef() and then pfind() 670 * which may grab the process lock. 671 * fdcheckstd() may call falloc() which may block to 672 * allocate memory, so temporarily drop the process lock. 673 */ 674 PROC_UNLOCK(p); 675 VOP_UNLOCK(imgp->vp, 0); 676 setugidsafety(td); 677 error = fdcheckstd(td); 678 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 679 if (error != 0) 680 goto done1; 681 PROC_LOCK(p); 682 /* 683 * Set the new credentials. 684 */ 685 if (attr.va_mode & S_ISUID) 686 change_euid(newcred, euip); 687 if (attr.va_mode & S_ISGID) 688 change_egid(newcred, attr.va_gid); 689#ifdef MAC 690 if (will_transition) { 691 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 692 interpvplabel, imgp); 693 } 694#endif 695 /* 696 * Implement correct POSIX saved-id behavior. 697 * 698 * XXXMAC: Note that the current logic will save the 699 * uid and gid if a MAC domain transition occurs, even 700 * though maybe it shouldn't. 701 */ 702 change_svuid(newcred, newcred->cr_uid); 703 change_svgid(newcred, newcred->cr_gid); 704 p->p_ucred = newcred; 705 newcred = NULL; 706 } else { 707 if (oldcred->cr_uid == oldcred->cr_ruid && 708 oldcred->cr_gid == oldcred->cr_rgid) 709 p->p_flag &= ~P_SUGID; 710 /* 711 * Implement correct POSIX saved-id behavior. 712 * 713 * XXX: It's not clear that the existing behavior is 714 * POSIX-compliant. A number of sources indicate that the 715 * saved uid/gid should only be updated if the new ruid is 716 * not equal to the old ruid, or the new euid is not equal 717 * to the old euid and the new euid is not equal to the old 718 * ruid. The FreeBSD code always updates the saved uid/gid. 719 * Also, this code uses the new (replaced) euid and egid as 720 * the source, which may or may not be the right ones to use. 721 */ 722 if (oldcred->cr_svuid != oldcred->cr_uid || 723 oldcred->cr_svgid != oldcred->cr_gid) { 724 change_svuid(newcred, newcred->cr_uid); 725 change_svgid(newcred, newcred->cr_gid); 726 p->p_ucred = newcred; 727 newcred = NULL; 728 } 729 } 730 731 /* 732 * Store the vp for use in procfs. This vnode was referenced prior 733 * to locking the proc lock. 734 */ 735 textvp = p->p_textvp; 736 p->p_textvp = binvp; 737 738#ifdef KDTRACE_HOOKS 739 /* 740 * Tell the DTrace fasttrap provider about the exec if it 741 * has declared an interest. 742 */ 743 if (dtrace_fasttrap_exec) 744 dtrace_fasttrap_exec(p); 745#endif 746 747 /* 748 * Notify others that we exec'd, and clear the P_INEXEC flag 749 * as we're now a bona fide freshly-execed process. 750 */ 751 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 752 p->p_flag &= ~P_INEXEC; 753 754 /* 755 * If tracing the process, trap to debugger so breakpoints 756 * can be set before the program executes. 757 * Use tdsignal to deliver signal to current thread, use 758 * psignal may cause the signal to be delivered to wrong thread 759 * because that thread will exit, remember we are going to enter 760 * single thread mode. 761 */ 762 if (p->p_flag & P_TRACED) 763 tdsignal(p, td, SIGTRAP, NULL); 764 765 /* clear "fork but no exec" flag, as we _are_ execing */ 766 p->p_acflag &= ~AFORK; 767 768 /* 769 * Free any previous argument cache and replace it with 770 * the new argument cache, if any. 771 */ 772 oldargs = p->p_args; 773 p->p_args = newargs; 774 newargs = NULL; 775 776#ifdef HWPMC_HOOKS 777 /* 778 * Check if system-wide sampling is in effect or if the 779 * current process is using PMCs. If so, do exec() time 780 * processing. This processing needs to happen AFTER the 781 * P_INEXEC flag is cleared. 782 * 783 * The proc lock needs to be released before taking the PMC 784 * SX. 785 */ 786 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 787 PROC_UNLOCK(p); 788 VOP_UNLOCK(imgp->vp, 0); 789 pe.pm_credentialschanged = credential_changing; 790 pe.pm_entryaddr = imgp->entry_addr; 791 792 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 793 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 794 } else 795 PROC_UNLOCK(p); 796#else /* !HWPMC_HOOKS */ 797 PROC_UNLOCK(p); 798#endif 799 800 /* Set values passed into the program in registers. */ 801 if (p->p_sysent->sv_setregs)
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806 807 vfs_mark_atime(imgp->vp, td->td_ucred); 808 809 SDT_PROBE(proc, kernel, , exec_success, args->fname, 0, 0, 0, 0); 810 811done1: 812 /* 813 * Free any resources malloc'd earlier that we didn't use. 814 */ 815 uifree(euip); 816 if (newcred == NULL) 817 crfree(oldcred); 818 else 819 crfree(newcred); 820 VOP_UNLOCK(imgp->vp, 0); 821 822 /* 823 * Handle deferred decrement of ref counts. 824 */ 825 if (textvp != NULL) { 826 int tvfslocked; 827 828 tvfslocked = VFS_LOCK_GIANT(textvp->v_mount); 829 vrele(textvp); 830 VFS_UNLOCK_GIANT(tvfslocked); 831 } 832 if (binvp && error != 0) 833 vrele(binvp); 834#ifdef KTRACE 835 if (tracevp != NULL) { 836 int tvfslocked; 837 838 tvfslocked = VFS_LOCK_GIANT(tracevp->v_mount); 839 vrele(tracevp); 840 VFS_UNLOCK_GIANT(tvfslocked); 841 } 842 if (tracecred != NULL) 843 crfree(tracecred); 844#endif 845 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 846 pargs_drop(oldargs); 847 pargs_drop(newargs); 848 if (oldsigacts != NULL) 849 sigacts_free(oldsigacts); 850 851exec_fail_dealloc: 852 853 /* 854 * free various allocated resources 855 */ 856 if (imgp->firstpage != NULL) 857 exec_unmap_first_page(imgp); 858 859 if (imgp->vp != NULL) { 860 if (args->fname) 861 NDFREE(&nd, NDF_ONLY_PNBUF); 862 if (imgp->opened) 863 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 864 vput(imgp->vp); 865 } 866 867 if (imgp->object != NULL) 868 vm_object_deallocate(imgp->object); 869 870 free(imgp->freepath, M_TEMP); 871 872 if (error == 0) { 873 /* 874 * Stop the process here if its stop event mask has 875 * the S_EXEC bit set. 876 */ 877 STOPEVENT(p, S_EXEC, 0); 878 goto done2; 879 } 880 881exec_fail: 882 /* we're done here, clear P_INEXEC */ 883 PROC_LOCK(p); 884 p->p_flag &= ~P_INEXEC; 885 PROC_UNLOCK(p); 886 887 SDT_PROBE(proc, kernel, , exec_failure, error, 0, 0, 0, 0); 888 889done2: 890#ifdef MAC 891 mac_execve_exit(imgp); 892 mac_execve_interpreter_exit(interpvplabel); 893#endif 894 VFS_UNLOCK_GIANT(vfslocked); 895 exec_free_args(args); 896 897 if (error && imgp->vmspace_destroyed) { 898 /* sorry, no more process anymore. exit gracefully */ 899 exit1(td, W_EXITCODE(0, SIGABRT)); 900 /* NOT REACHED */ 901 } 902 return (error); 903} 904 905int 906exec_map_first_page(imgp) 907 struct image_params *imgp; 908{ 909 int rv, i; 910 int initial_pagein; 911 vm_page_t ma[VM_INITIAL_PAGEIN]; 912 vm_object_t object; 913 914 if (imgp->firstpage != NULL) 915 exec_unmap_first_page(imgp); 916 917 object = imgp->vp->v_object; 918 if (object == NULL) 919 return (EACCES); 920 VM_OBJECT_LOCK(object); 921#if VM_NRESERVLEVEL > 0 922 if ((object->flags & OBJ_COLORED) == 0) { 923 object->flags |= OBJ_COLORED; 924 object->pg_color = 0; 925 } 926#endif 927 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 928 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 929 initial_pagein = VM_INITIAL_PAGEIN; 930 if (initial_pagein > object->size) 931 initial_pagein = object->size; 932 for (i = 1; i < initial_pagein; i++) { 933 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 934 if (ma[i]->valid) 935 break; 936 if ((ma[i]->oflags & VPO_BUSY) || ma[i]->busy) 937 break; 938 vm_page_busy(ma[i]); 939 } else { 940 ma[i] = vm_page_alloc(object, i, 941 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 942 if (ma[i] == NULL) 943 break; 944 } 945 } 946 initial_pagein = i; 947 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 948 ma[0] = vm_page_lookup(object, 0); 949 if ((rv != VM_PAGER_OK) || (ma[0] == NULL)) { 950 if (ma[0]) { 951 vm_page_lock_queues(); 952 vm_page_free(ma[0]); 953 vm_page_unlock_queues(); 954 } 955 VM_OBJECT_UNLOCK(object); 956 return (EIO); 957 } 958 } 959 vm_page_lock_queues(); 960 vm_page_hold(ma[0]); 961 vm_page_unlock_queues(); 962 vm_page_wakeup(ma[0]); 963 VM_OBJECT_UNLOCK(object); 964 965 imgp->firstpage = sf_buf_alloc(ma[0], 0); 966 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 967 968 return (0); 969} 970 971void 972exec_unmap_first_page(imgp) 973 struct image_params *imgp; 974{ 975 vm_page_t m; 976 977 if (imgp->firstpage != NULL) { 978 m = sf_buf_page(imgp->firstpage); 979 sf_buf_free(imgp->firstpage); 980 imgp->firstpage = NULL; 981 vm_page_lock_queues(); 982 vm_page_unhold(m); 983 vm_page_unlock_queues(); 984 } 985} 986 987/* 988 * Destroy old address space, and allocate a new stack 989 * The new stack is only SGROWSIZ large because it is grown 990 * automatically in trap.c. 991 */ 992int 993exec_new_vmspace(imgp, sv) 994 struct image_params *imgp; 995 struct sysentvec *sv; 996{ 997 int error; 998 struct proc *p = imgp->proc; 999 struct vmspace *vmspace = p->p_vmspace; 1000 vm_offset_t sv_minuser, stack_addr; 1001 vm_map_t map; 1002 u_long ssiz; 1003 1004 imgp->vmspace_destroyed = 1; 1005 imgp->sysent = sv; 1006 1007 /* May be called with Giant held */ 1008 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1009 1010 /* 1011 * Blow away entire process VM, if address space not shared, 1012 * otherwise, create a new VM space so that other threads are 1013 * not disrupted 1014 */ 1015 map = &vmspace->vm_map; 1016 if (map_at_zero) 1017 sv_minuser = sv->sv_minuser; 1018 else 1019 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1020 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1021 vm_map_max(map) == sv->sv_maxuser) { 1022 shmexit(vmspace); 1023 pmap_remove_pages(vmspace_pmap(vmspace)); 1024 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1025 } else { 1026 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1027 if (error) 1028 return (error); 1029 vmspace = p->p_vmspace; 1030 map = &vmspace->vm_map; 1031 } 1032 1033 /* Allocate a new stack */ 1034 if (sv->sv_maxssiz != NULL) 1035 ssiz = *sv->sv_maxssiz; 1036 else 1037 ssiz = maxssiz; 1038 stack_addr = sv->sv_usrstack - ssiz; 1039 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1040 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1041 if (error) 1042 return (error); 1043 1044#ifdef __ia64__ 1045 /* Allocate a new register stack */ 1046 stack_addr = IA64_BACKINGSTORE; 1047 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1048 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP); 1049 if (error) 1050 return (error); 1051#endif 1052 1053 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 1054 * VM_STACK case, but they are still used to monitor the size of the 1055 * process stack so we can check the stack rlimit. 1056 */ 1057 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1058 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1059 1060 return (0); 1061} 1062 1063/* 1064 * Copy out argument and environment strings from the old process address 1065 * space into the temporary string buffer. 1066 */ 1067int 1068exec_copyin_args(struct image_args *args, char *fname, 1069 enum uio_seg segflg, char **argv, char **envv) 1070{ 1071 char *argp, *envp; 1072 int error; 1073 size_t length; 1074 1075 bzero(args, sizeof(*args)); 1076 if (argv == NULL) 1077 return (EFAULT); 1078 /* 1079 * Allocate temporary demand zeroed space for argument and 1080 * environment strings: 1081 * 1082 * o ARG_MAX for argument and environment; 1083 * o MAXSHELLCMDLEN for the name of interpreters. 1084 */ 1085 args->buf = (char *) kmem_alloc_wait(exec_map, 1086 PATH_MAX + ARG_MAX + MAXSHELLCMDLEN); 1087 if (args->buf == NULL) 1088 return (ENOMEM); 1089 args->begin_argv = args->buf; 1090 args->endp = args->begin_argv; 1091 args->stringspace = ARG_MAX; 1092 /* 1093 * Copy the file name. 1094 */ 1095 if (fname != NULL) { 1096 args->fname = args->buf + ARG_MAX; 1097 error = (segflg == UIO_SYSSPACE) ? 1098 copystr(fname, args->fname, PATH_MAX, &length) : 1099 copyinstr(fname, args->fname, PATH_MAX, &length); 1100 if (error != 0) 1101 goto err_exit; 1102 } else 1103 args->fname = NULL; 1104 1105 /* 1106 * extract arguments first 1107 */ 1108 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 1109 if (argp == (caddr_t) -1) { 1110 error = EFAULT; 1111 goto err_exit; 1112 } 1113 if ((error = copyinstr(argp, args->endp, 1114 args->stringspace, &length))) { 1115 if (error == ENAMETOOLONG) 1116 error = E2BIG; 1117 goto err_exit; 1118 } 1119 args->stringspace -= length; 1120 args->endp += length; 1121 args->argc++; 1122 } 1123 1124 args->begin_envv = args->endp; 1125 1126 /* 1127 * extract environment strings 1128 */ 1129 if (envv) { 1130 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) { 1131 if (envp == (caddr_t)-1) { 1132 error = EFAULT; 1133 goto err_exit; 1134 } 1135 if ((error = copyinstr(envp, args->endp, 1136 args->stringspace, &length))) { 1137 if (error == ENAMETOOLONG) 1138 error = E2BIG; 1139 goto err_exit; 1140 } 1141 args->stringspace -= length; 1142 args->endp += length; 1143 args->envc++; 1144 } 1145 } 1146 1147 return (0); 1148 1149err_exit: 1150 exec_free_args(args); 1151 return (error); 1152} 1153 1154static void 1155exec_free_args(struct image_args *args) 1156{ 1157 1158 if (args->buf) { 1159 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf, 1160 PATH_MAX + ARG_MAX + MAXSHELLCMDLEN); 1161 args->buf = NULL; 1162 } 1163} 1164 1165/* 1166 * Copy strings out to the new process address space, constructing new arg 1167 * and env vector tables. Return a pointer to the base so that it can be used 1168 * as the initial stack pointer. 1169 */ 1170register_t * 1171exec_copyout_strings(imgp) 1172 struct image_params *imgp; 1173{ 1174 int argc, envc; 1175 char **vectp; 1176 char *stringp, *destp; 1177 register_t *stack_base; 1178 struct ps_strings *arginfo; 1179 struct proc *p; 1180 size_t execpath_len; 1181 int szsigcode; 1182 1183 /* 1184 * Calculate string base and vector table pointers. 1185 * Also deal with signal trampoline code for this exec type. 1186 */ 1187 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1188 execpath_len = strlen(imgp->execpath) + 1; 1189 else 1190 execpath_len = 0; 1191 p = imgp->proc; 1192 szsigcode = 0; 1193 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1194 if (p->p_sysent->sv_szsigcode != NULL) 1195 szsigcode = *(p->p_sysent->sv_szsigcode); 1196 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 1197 roundup(execpath_len, sizeof(char *)) - 1198 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *)); 1199 1200 /* 1201 * install sigcode 1202 */ 1203 if (szsigcode) 1204 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo - 1205 szsigcode), szsigcode); 1206 1207 /* 1208 * Copy the image path for the rtld. 1209 */ 1210 if (execpath_len != 0) { 1211 imgp->execpathp = (uintptr_t)arginfo - szsigcode - execpath_len; 1212 copyout(imgp->execpath, (void *)imgp->execpathp, 1213 execpath_len); 1214 } 1215 1216 /* 1217 * If we have a valid auxargs ptr, prepare some room 1218 * on the stack. 1219 */ 1220 if (imgp->auxargs) { 1221 /* 1222 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1223 * lower compatibility. 1224 */ 1225 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1226 (AT_COUNT * 2); 1227 /* 1228 * The '+ 2' is for the null pointers at the end of each of 1229 * the arg and env vector sets,and imgp->auxarg_size is room 1230 * for argument of Runtime loader. 1231 */ 1232 vectp = (char **)(destp - (imgp->args->argc + 1233 imgp->args->envc + 2 + imgp->auxarg_size + execpath_len) * 1234 sizeof(char *)); 1235 } else { 1236 /* 1237 * The '+ 2' is for the null pointers at the end of each of 1238 * the arg and env vector sets 1239 */ 1240 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) * 1241 sizeof(char *)); 1242 } 1243 1244 /* 1245 * vectp also becomes our initial stack base 1246 */ 1247 stack_base = (register_t *)vectp; 1248 1249 stringp = imgp->args->begin_argv; 1250 argc = imgp->args->argc; 1251 envc = imgp->args->envc; 1252 1253 /* 1254 * Copy out strings - arguments and environment. 1255 */ 1256 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace); 1257 1258 /* 1259 * Fill in "ps_strings" struct for ps, w, etc. 1260 */ 1261 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1262 suword32(&arginfo->ps_nargvstr, argc); 1263 1264 /* 1265 * Fill in argument portion of vector table. 1266 */ 1267 for (; argc > 0; --argc) { 1268 suword(vectp++, (long)(intptr_t)destp); 1269 while (*stringp++ != 0) 1270 destp++; 1271 destp++; 1272 } 1273 1274 /* a null vector table pointer separates the argp's from the envp's */ 1275 suword(vectp++, 0); 1276 1277 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1278 suword32(&arginfo->ps_nenvstr, envc); 1279 1280 /* 1281 * Fill in environment portion of vector table. 1282 */ 1283 for (; envc > 0; --envc) { 1284 suword(vectp++, (long)(intptr_t)destp); 1285 while (*stringp++ != 0) 1286 destp++; 1287 destp++; 1288 } 1289 1290 /* end of vector table is a null pointer */ 1291 suword(vectp, 0); 1292 1293 return (stack_base); 1294} 1295 1296/* 1297 * Check permissions of file to execute. 1298 * Called with imgp->vp locked. 1299 * Return 0 for success or error code on failure. 1300 */ 1301int 1302exec_check_permissions(imgp) 1303 struct image_params *imgp; 1304{ 1305 struct vnode *vp = imgp->vp; 1306 struct vattr *attr = imgp->attr; 1307 struct thread *td; 1308 int error; 1309 1310 td = curthread; 1311 1312 /* Get file attributes */ 1313 error = VOP_GETATTR(vp, attr, td->td_ucred); 1314 if (error) 1315 return (error); 1316 1317#ifdef MAC 1318 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1319 if (error) 1320 return (error); 1321#endif 1322 1323 /* 1324 * 1) Check if file execution is disabled for the filesystem that this 1325 * file resides on. 1326 * 2) Insure that at least one execute bit is on - otherwise root 1327 * will always succeed, and we don't want to happen unless the 1328 * file really is executable. 1329 * 3) Insure that the file is a regular file. 1330 */ 1331 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1332 ((attr->va_mode & 0111) == 0) || 1333 (attr->va_type != VREG)) 1334 return (EACCES); 1335 1336 /* 1337 * Zero length files can't be exec'd 1338 */ 1339 if (attr->va_size == 0) 1340 return (ENOEXEC); 1341 1342 /* 1343 * Check for execute permission to file based on current credentials. 1344 */ 1345 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1346 if (error) 1347 return (error); 1348 1349 /* 1350 * Check number of open-for-writes on the file and deny execution 1351 * if there are any. 1352 */ 1353 if (vp->v_writecount) 1354 return (ETXTBSY); 1355 1356 /* 1357 * Call filesystem specific open routine (which does nothing in the 1358 * general case). 1359 */ 1360 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1361 if (error == 0) 1362 imgp->opened = 1; 1363 return (error); 1364} 1365 1366/* 1367 * Exec handler registration 1368 */ 1369int 1370exec_register(execsw_arg) 1371 const struct execsw *execsw_arg; 1372{ 1373 const struct execsw **es, **xs, **newexecsw; 1374 int count = 2; /* New slot and trailing NULL */ 1375 1376 if (execsw) 1377 for (es = execsw; *es; es++) 1378 count++; 1379 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1380 if (newexecsw == NULL) 1381 return (ENOMEM); 1382 xs = newexecsw; 1383 if (execsw) 1384 for (es = execsw; *es; es++) 1385 *xs++ = *es; 1386 *xs++ = execsw_arg; 1387 *xs = NULL; 1388 if (execsw) 1389 free(execsw, M_TEMP); 1390 execsw = newexecsw; 1391 return (0); 1392} 1393 1394int 1395exec_unregister(execsw_arg) 1396 const struct execsw *execsw_arg; 1397{ 1398 const struct execsw **es, **xs, **newexecsw; 1399 int count = 1; 1400 1401 if (execsw == NULL) 1402 panic("unregister with no handlers left?\n"); 1403 1404 for (es = execsw; *es; es++) { 1405 if (*es == execsw_arg) 1406 break; 1407 } 1408 if (*es == NULL) 1409 return (ENOENT); 1410 for (es = execsw; *es; es++) 1411 if (*es != execsw_arg) 1412 count++; 1413 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1414 if (newexecsw == NULL) 1415 return (ENOMEM); 1416 xs = newexecsw; 1417 for (es = execsw; *es; es++) 1418 if (*es != execsw_arg) 1419 *xs++ = *es; 1420 *xs = NULL; 1421 if (execsw) 1422 free(execsw, M_TEMP); 1423 execsw = newexecsw; 1424 return (0); 1425}
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