Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_exec.c
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1 /*- 2 * Copyright (c) 1993, David Greenman 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 #include "opt_hwpmc_hooks.h" 31 #include "opt_ktrace.h" 32 #include "opt_mac.h" 33 34 #include <sys/param.h> 35 #include <sys/systm.h> 36 #include <sys/eventhandler.h> 37 #include <sys/lock.h> 38 #include <sys/mutex.h> 39 #include <sys/sysproto.h> 40 #include <sys/signalvar.h> 41 #include <sys/kernel.h> 42 #include <sys/mac.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/proc.h> 53 #include <sys/pioctl.h> 54 #include <sys/namei.h> 55 #include <sys/resourcevar.h> 56 #include <sys/sf_buf.h> 57 #include <sys/syscallsubr.h> 58 #include <sys/sysent.h> 59 #include <sys/shm.h> 60 #include <sys/sysctl.h> 61 #include <sys/vnode.h> 62 #ifdef KTRACE 63 #include <sys/ktrace.h> 64 #endif 65 66 #include <vm/vm.h> 67 #include <vm/vm_param.h> 68 #include <vm/pmap.h> 69 #include <vm/vm_page.h> 70 #include <vm/vm_map.h> 71 #include <vm/vm_kern.h> 72 #include <vm/vm_extern.h> 73 #include <vm/vm_object.h> 74 #include <vm/vm_pager.h> 75 76 #ifdef HWPMC_HOOKS 77 #include <sys/pmckern.h> 78 #endif 79 80 #include <machine/reg.h> 81 82 #include <security/audit/audit.h> 83 84 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 85 86 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 87 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 88 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 89 static int do_execve(struct thread *td, struct image_args *args, 90 struct mac *mac_p); 91 92 /* XXX This should be vm_size_t. */ 93 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD, 94 NULL, 0, sysctl_kern_ps_strings, "LU", ""); 95 96 /* XXX This should be vm_size_t. */ 97 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD, 98 NULL, 0, sysctl_kern_usrstack, "LU", ""); 99 100 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 101 NULL, 0, sysctl_kern_stackprot, "I", ""); 102 103 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 104 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 105 &ps_arg_cache_limit, 0, ""); 106 107 SYSCTL_DECL(_security_bsd); 108 109 static int map_at_zero = 1; 110 TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero); 111 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &map_at_zero, 0, 112 "Permit processes to map an object at virtual address 0."); 113 114 static int 115 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 116 { 117 struct proc *p; 118 int error; 119 120 p = curproc; 121 #ifdef SCTL_MASK32 122 if (req->flags & SCTL_MASK32) { 123 unsigned int val; 124 val = (unsigned int)p->p_sysent->sv_psstrings; 125 error = SYSCTL_OUT(req, &val, sizeof(val)); 126 } else 127 #endif 128 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 129 sizeof(p->p_sysent->sv_psstrings)); 130 return error; 131 } 132 133 static int 134 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 135 { 136 struct proc *p; 137 int error; 138 139 p = curproc; 140 #ifdef SCTL_MASK32 141 if (req->flags & SCTL_MASK32) { 142 unsigned int val; 143 val = (unsigned int)p->p_sysent->sv_usrstack; 144 error = SYSCTL_OUT(req, &val, sizeof(val)); 145 } else 146 #endif 147 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 148 sizeof(p->p_sysent->sv_usrstack)); 149 return error; 150 } 151 152 static int 153 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 154 { 155 struct proc *p; 156 157 p = curproc; 158 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 159 sizeof(p->p_sysent->sv_stackprot))); 160 } 161 162 /* 163 * Each of the items is a pointer to a `const struct execsw', hence the 164 * double pointer here. 165 */ 166 static const struct execsw **execsw; 167 168 #ifndef _SYS_SYSPROTO_H_ 169 struct execve_args { 170 char *fname; 171 char **argv; 172 char **envv; 173 }; 174 #endif 175 176 /* 177 * MPSAFE 178 */ 179 int 180 execve(td, uap) 181 struct thread *td; 182 struct execve_args /* { 183 char *fname; 184 char **argv; 185 char **envv; 186 } */ *uap; 187 { 188 int error; 189 struct image_args args; 190 191 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 192 uap->argv, uap->envv); 193 194 if (error == 0) 195 error = kern_execve(td, &args, NULL); 196 197 exec_free_args(&args); 198 199 return (error); 200 } 201 202 #ifndef _SYS_SYSPROTO_H_ 203 struct __mac_execve_args { 204 char *fname; 205 char **argv; 206 char **envv; 207 struct mac *mac_p; 208 }; 209 #endif 210 211 /* 212 * MPSAFE 213 */ 214 int 215 __mac_execve(td, uap) 216 struct thread *td; 217 struct __mac_execve_args /* { 218 char *fname; 219 char **argv; 220 char **envv; 221 struct mac *mac_p; 222 } */ *uap; 223 { 224 #ifdef MAC 225 int error; 226 struct image_args args; 227 228 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 229 uap->argv, uap->envv); 230 231 if (error == 0) 232 error = kern_execve(td, &args, uap->mac_p); 233 234 exec_free_args(&args); 235 236 return (error); 237 #else 238 return (ENOSYS); 239 #endif 240 } 241 242 /* 243 * XXX: kern_execve has the astonishing property of not always 244 * returning to the caller. If sufficiently bad things happen during 245 * the call to do_execve(), it can end up calling exit1(); as a result, 246 * callers must avoid doing anything which they might need to undo 247 * (e.g., allocating memory). 248 */ 249 int 250 kern_execve(td, args, mac_p) 251 struct thread *td; 252 struct image_args *args; 253 struct mac *mac_p; 254 { 255 struct proc *p = td->td_proc; 256 int error; 257 258 AUDIT_ARG(argv, args->begin_argv, args->argc, 259 args->begin_envv - args->begin_argv); 260 AUDIT_ARG(envv, args->begin_envv, args->envc, 261 args->endp - args->begin_envv); 262 if (p->p_flag & P_HADTHREADS) { 263 PROC_LOCK(p); 264 if (thread_single(SINGLE_BOUNDARY)) { 265 PROC_UNLOCK(p); 266 return (ERESTART); /* Try again later. */ 267 } 268 PROC_UNLOCK(p); 269 } 270 271 error = do_execve(td, args, mac_p); 272 273 if (p->p_flag & P_HADTHREADS) { 274 PROC_LOCK(p); 275 /* 276 * If success, we upgrade to SINGLE_EXIT state to 277 * force other threads to suicide. 278 */ 279 if (error == 0) 280 thread_single(SINGLE_EXIT); 281 else 282 thread_single_end(); 283 PROC_UNLOCK(p); 284 } 285 286 return (error); 287 } 288 289 /* 290 * In-kernel implementation of execve(). All arguments are assumed to be 291 * userspace pointers from the passed thread. 292 * 293 * MPSAFE 294 */ 295 static int 296 do_execve(td, args, mac_p) 297 struct thread *td; 298 struct image_args *args; 299 struct mac *mac_p; 300 { 301 struct proc *p = td->td_proc; 302 struct nameidata nd, *ndp; 303 struct ucred *newcred = NULL, *oldcred; 304 struct uidinfo *euip; 305 register_t *stack_base; 306 int error, len, i; 307 struct image_params image_params, *imgp; 308 struct vattr attr; 309 int (*img_first)(struct image_params *); 310 struct pargs *oldargs = NULL, *newargs = NULL; 311 struct sigacts *oldsigacts, *newsigacts; 312 #ifdef KTRACE 313 struct vnode *tracevp = NULL; 314 struct ucred *tracecred = NULL; 315 #endif 316 struct vnode *textvp = NULL; 317 int credential_changing; 318 int vfslocked; 319 int textset; 320 #ifdef MAC 321 struct label *interplabel = NULL; 322 int will_transition; 323 #endif 324 #ifdef HWPMC_HOOKS 325 struct pmckern_procexec pe; 326 #endif 327 328 vfslocked = 0; 329 imgp = &image_params; 330 331 /* 332 * Lock the process and set the P_INEXEC flag to indicate that 333 * it should be left alone until we're done here. This is 334 * necessary to avoid race conditions - e.g. in ptrace() - 335 * that might allow a local user to illicitly obtain elevated 336 * privileges. 337 */ 338 PROC_LOCK(p); 339 KASSERT((p->p_flag & P_INEXEC) == 0, 340 ("%s(): process already has P_INEXEC flag", __func__)); 341 p->p_flag |= P_INEXEC; 342 PROC_UNLOCK(p); 343 344 /* 345 * Initialize part of the common data 346 */ 347 imgp->proc = p; 348 imgp->execlabel = NULL; 349 imgp->attr = &attr; 350 imgp->entry_addr = 0; 351 imgp->vmspace_destroyed = 0; 352 imgp->interpreted = 0; 353 imgp->interpreter_name = args->buf + PATH_MAX + ARG_MAX; 354 imgp->auxargs = NULL; 355 imgp->vp = NULL; 356 imgp->object = NULL; 357 imgp->firstpage = NULL; 358 imgp->ps_strings = 0; 359 imgp->auxarg_size = 0; 360 imgp->args = args; 361 362 #ifdef MAC 363 error = mac_execve_enter(imgp, mac_p); 364 if (error) 365 goto exec_fail; 366 #endif 367 368 imgp->image_header = NULL; 369 370 /* 371 * Translate the file name. namei() returns a vnode pointer 372 * in ni_vp amoung other things. 373 * 374 * XXXAUDIT: It would be desirable to also audit the name of the 375 * interpreter if this is an interpreted binary. 376 */ 377 ndp = &nd; 378 NDINIT(ndp, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME | MPSAFE | 379 AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 380 381 interpret: 382 error = namei(ndp); 383 if (error) 384 goto exec_fail; 385 386 vfslocked = NDHASGIANT(ndp); 387 imgp->vp = ndp->ni_vp; 388 389 /* 390 * Check file permissions (also 'opens' file) 391 */ 392 error = exec_check_permissions(imgp); 393 if (error) 394 goto exec_fail_dealloc; 395 396 imgp->object = imgp->vp->v_object; 397 if (imgp->object != NULL) 398 vm_object_reference(imgp->object); 399 400 /* 401 * Set VV_TEXT now so no one can write to the executable while we're 402 * activating it. 403 * 404 * Remember if this was set before and unset it in case this is not 405 * actually an executable image. 406 */ 407 textset = imgp->vp->v_vflag & VV_TEXT; 408 imgp->vp->v_vflag |= VV_TEXT; 409 410 error = exec_map_first_page(imgp); 411 if (error) 412 goto exec_fail_dealloc; 413 414 /* 415 * If the current process has a special image activator it 416 * wants to try first, call it. For example, emulating shell 417 * scripts differently. 418 */ 419 error = -1; 420 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 421 error = img_first(imgp); 422 423 /* 424 * Loop through the list of image activators, calling each one. 425 * An activator returns -1 if there is no match, 0 on success, 426 * and an error otherwise. 427 */ 428 for (i = 0; error == -1 && execsw[i]; ++i) { 429 if (execsw[i]->ex_imgact == NULL || 430 execsw[i]->ex_imgact == img_first) { 431 continue; 432 } 433 error = (*execsw[i]->ex_imgact)(imgp); 434 } 435 436 if (error) { 437 if (error == -1) { 438 if (textset == 0) 439 imgp->vp->v_vflag &= ~VV_TEXT; 440 error = ENOEXEC; 441 } 442 goto exec_fail_dealloc; 443 } 444 445 /* 446 * Special interpreter operation, cleanup and loop up to try to 447 * activate the interpreter. 448 */ 449 if (imgp->interpreted) { 450 exec_unmap_first_page(imgp); 451 /* 452 * VV_TEXT needs to be unset for scripts. There is a short 453 * period before we determine that something is a script where 454 * VV_TEXT will be set. The vnode lock is held over this 455 * entire period so nothing should illegitimately be blocked. 456 */ 457 imgp->vp->v_vflag &= ~VV_TEXT; 458 /* free name buffer and old vnode */ 459 NDFREE(ndp, NDF_ONLY_PNBUF); 460 #ifdef MAC 461 interplabel = mac_vnode_label_alloc(); 462 mac_copy_vnode_label(ndp->ni_vp->v_label, interplabel); 463 #endif 464 vput(ndp->ni_vp); 465 vm_object_deallocate(imgp->object); 466 imgp->object = NULL; 467 VFS_UNLOCK_GIANT(vfslocked); 468 vfslocked = 0; 469 /* set new name to that of the interpreter */ 470 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME | MPSAFE, 471 UIO_SYSSPACE, imgp->interpreter_name, td); 472 goto interpret; 473 } 474 475 /* 476 * Copy out strings (args and env) and initialize stack base 477 */ 478 if (p->p_sysent->sv_copyout_strings) 479 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 480 else 481 stack_base = exec_copyout_strings(imgp); 482 483 /* 484 * If custom stack fixup routine present for this process 485 * let it do the stack setup. 486 * Else stuff argument count as first item on stack 487 */ 488 if (p->p_sysent->sv_fixup != NULL) 489 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 490 else 491 suword(--stack_base, imgp->args->argc); 492 493 /* 494 * For security and other reasons, the file descriptor table cannot 495 * be shared after an exec. 496 */ 497 fdunshare(p, td); 498 499 /* 500 * Malloc things before we need locks. 501 */ 502 newcred = crget(); 503 euip = uifind(attr.va_uid); 504 i = imgp->args->begin_envv - imgp->args->begin_argv; 505 /* Cache arguments if they fit inside our allowance */ 506 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 507 newargs = pargs_alloc(i); 508 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 509 } 510 511 /* close files on exec */ 512 VOP_UNLOCK(imgp->vp, 0, td); 513 fdcloseexec(td); 514 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY, td); 515 516 /* Get a reference to the vnode prior to locking the proc */ 517 VREF(ndp->ni_vp); 518 519 /* 520 * For security and other reasons, signal handlers cannot 521 * be shared after an exec. The new process gets a copy of the old 522 * handlers. In execsigs(), the new process will have its signals 523 * reset. 524 */ 525 PROC_LOCK(p); 526 if (sigacts_shared(p->p_sigacts)) { 527 oldsigacts = p->p_sigacts; 528 PROC_UNLOCK(p); 529 newsigacts = sigacts_alloc(); 530 sigacts_copy(newsigacts, oldsigacts); 531 PROC_LOCK(p); 532 p->p_sigacts = newsigacts; 533 } else 534 oldsigacts = NULL; 535 536 /* Stop profiling */ 537 stopprofclock(p); 538 539 /* reset caught signals */ 540 execsigs(p); 541 542 /* name this process - nameiexec(p, ndp) */ 543 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 544 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 545 p->p_comm[len] = 0; 546 547 /* 548 * mark as execed, wakeup the process that vforked (if any) and tell 549 * it that it now has its own resources back 550 */ 551 p->p_flag |= P_EXEC; 552 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 553 p->p_flag &= ~P_PPWAIT; 554 wakeup(p->p_pptr); 555 } 556 557 /* 558 * Implement image setuid/setgid. 559 * 560 * Don't honor setuid/setgid if the filesystem prohibits it or if 561 * the process is being traced. 562 * 563 * XXXMAC: For the time being, use NOSUID to also prohibit 564 * transitions on the file system. 565 */ 566 oldcred = p->p_ucred; 567 credential_changing = 0; 568 credential_changing |= (attr.va_mode & VSUID) && oldcred->cr_uid != 569 attr.va_uid; 570 credential_changing |= (attr.va_mode & VSGID) && oldcred->cr_gid != 571 attr.va_gid; 572 #ifdef MAC 573 will_transition = mac_execve_will_transition(oldcred, imgp->vp, 574 interplabel, imgp); 575 credential_changing |= will_transition; 576 #endif 577 578 if (credential_changing && 579 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 580 (p->p_flag & P_TRACED) == 0) { 581 /* 582 * Turn off syscall tracing for set-id programs, except for 583 * root. Record any set-id flags first to make sure that 584 * we do not regain any tracing during a possible block. 585 */ 586 setsugid(p); 587 #ifdef KTRACE 588 if (p->p_tracevp != NULL && suser_cred(oldcred, SUSER_ALLOWJAIL)) { 589 mtx_lock(&ktrace_mtx); 590 p->p_traceflag = 0; 591 tracevp = p->p_tracevp; 592 p->p_tracevp = NULL; 593 tracecred = p->p_tracecred; 594 p->p_tracecred = NULL; 595 mtx_unlock(&ktrace_mtx); 596 } 597 #endif 598 /* 599 * Close any file descriptors 0..2 that reference procfs, 600 * then make sure file descriptors 0..2 are in use. 601 * 602 * setugidsafety() may call closef() and then pfind() 603 * which may grab the process lock. 604 * fdcheckstd() may call falloc() which may block to 605 * allocate memory, so temporarily drop the process lock. 606 */ 607 PROC_UNLOCK(p); 608 setugidsafety(td); 609 VOP_UNLOCK(imgp->vp, 0, td); 610 error = fdcheckstd(td); 611 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY, td); 612 if (error != 0) 613 goto done1; 614 PROC_LOCK(p); 615 /* 616 * Set the new credentials. 617 */ 618 crcopy(newcred, oldcred); 619 if (attr.va_mode & VSUID) 620 change_euid(newcred, euip); 621 if (attr.va_mode & VSGID) 622 change_egid(newcred, attr.va_gid); 623 #ifdef MAC 624 if (will_transition) { 625 mac_execve_transition(oldcred, newcred, imgp->vp, 626 interplabel, imgp); 627 } 628 #endif 629 /* 630 * Implement correct POSIX saved-id behavior. 631 * 632 * XXXMAC: Note that the current logic will save the 633 * uid and gid if a MAC domain transition occurs, even 634 * though maybe it shouldn't. 635 */ 636 change_svuid(newcred, newcred->cr_uid); 637 change_svgid(newcred, newcred->cr_gid); 638 p->p_ucred = newcred; 639 newcred = NULL; 640 } else { 641 if (oldcred->cr_uid == oldcred->cr_ruid && 642 oldcred->cr_gid == oldcred->cr_rgid) 643 p->p_flag &= ~P_SUGID; 644 /* 645 * Implement correct POSIX saved-id behavior. 646 * 647 * XXX: It's not clear that the existing behavior is 648 * POSIX-compliant. A number of sources indicate that the 649 * saved uid/gid should only be updated if the new ruid is 650 * not equal to the old ruid, or the new euid is not equal 651 * to the old euid and the new euid is not equal to the old 652 * ruid. The FreeBSD code always updates the saved uid/gid. 653 * Also, this code uses the new (replaced) euid and egid as 654 * the source, which may or may not be the right ones to use. 655 */ 656 if (oldcred->cr_svuid != oldcred->cr_uid || 657 oldcred->cr_svgid != oldcred->cr_gid) { 658 crcopy(newcred, oldcred); 659 change_svuid(newcred, newcred->cr_uid); 660 change_svgid(newcred, newcred->cr_gid); 661 p->p_ucred = newcred; 662 newcred = NULL; 663 } 664 } 665 666 /* 667 * Store the vp for use in procfs. This vnode was referenced prior 668 * to locking the proc lock. 669 */ 670 textvp = p->p_textvp; 671 p->p_textvp = ndp->ni_vp; 672 673 /* 674 * Notify others that we exec'd, and clear the P_INEXEC flag 675 * as we're now a bona fide freshly-execed process. 676 */ 677 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 678 p->p_flag &= ~P_INEXEC; 679 680 /* 681 * If tracing the process, trap to debugger so breakpoints 682 * can be set before the program executes. 683 * Use tdsignal to deliver signal to current thread, use 684 * psignal may cause the signal to be delivered to wrong thread 685 * because that thread will exit, remember we are going to enter 686 * single thread mode. 687 */ 688 if (p->p_flag & P_TRACED) 689 tdsignal(td, SIGTRAP, SIGTARGET_TD); 690 691 /* clear "fork but no exec" flag, as we _are_ execing */ 692 p->p_acflag &= ~AFORK; 693 694 /* 695 * Free any previous argument cache and replace it with 696 * the new argument cache, if any. 697 */ 698 oldargs = p->p_args; 699 p->p_args = newargs; 700 newargs = NULL; 701 702 #ifdef HWPMC_HOOKS 703 /* 704 * Check if system-wide sampling is in effect or if the 705 * current process is using PMCs. If so, do exec() time 706 * processing. This processing needs to happen AFTER the 707 * P_INEXEC flag is cleared. 708 * 709 * The proc lock needs to be released before taking the PMC 710 * SX. 711 */ 712 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 713 PROC_UNLOCK(p); 714 pe.pm_credentialschanged = credential_changing; 715 pe.pm_entryaddr = imgp->entry_addr; 716 717 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 718 } else 719 PROC_UNLOCK(p); 720 #else /* !HWPMC_HOOKS */ 721 PROC_UNLOCK(p); 722 #endif 723 724 /* Set values passed into the program in registers. */ 725 if (p->p_sysent->sv_setregs) 726 (*p->p_sysent->sv_setregs)(td, imgp->entry_addr, 727 (u_long)(uintptr_t)stack_base, imgp->ps_strings); 728 else 729 exec_setregs(td, imgp->entry_addr, 730 (u_long)(uintptr_t)stack_base, imgp->ps_strings); 731 732 vfs_mark_atime(imgp->vp, td); 733 734 done1: 735 /* 736 * Free any resources malloc'd earlier that we didn't use. 737 */ 738 uifree(euip); 739 if (newcred == NULL) 740 crfree(oldcred); 741 else 742 crfree(newcred); 743 VOP_UNLOCK(imgp->vp, 0, td); 744 /* 745 * Handle deferred decrement of ref counts. 746 */ 747 if (textvp != NULL) { 748 int tvfslocked; 749 750 tvfslocked = VFS_LOCK_GIANT(textvp->v_mount); 751 vrele(textvp); 752 VFS_UNLOCK_GIANT(tvfslocked); 753 } 754 if (ndp->ni_vp && error != 0) 755 vrele(ndp->ni_vp); 756 #ifdef KTRACE 757 if (tracevp != NULL) { 758 int tvfslocked; 759 760 tvfslocked = VFS_LOCK_GIANT(tracevp->v_mount); 761 vrele(tracevp); 762 VFS_UNLOCK_GIANT(tvfslocked); 763 } 764 if (tracecred != NULL) 765 crfree(tracecred); 766 #endif 767 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY, td); 768 if (oldargs != NULL) 769 pargs_drop(oldargs); 770 if (newargs != NULL) 771 pargs_drop(newargs); 772 if (oldsigacts != NULL) 773 sigacts_free(oldsigacts); 774 775 exec_fail_dealloc: 776 777 /* 778 * free various allocated resources 779 */ 780 if (imgp->firstpage != NULL) 781 exec_unmap_first_page(imgp); 782 783 if (imgp->vp != NULL) { 784 NDFREE(ndp, NDF_ONLY_PNBUF); 785 vput(imgp->vp); 786 } 787 788 if (imgp->object != NULL) 789 vm_object_deallocate(imgp->object); 790 791 if (error == 0) { 792 /* 793 * Stop the process here if its stop event mask has 794 * the S_EXEC bit set. 795 */ 796 STOPEVENT(p, S_EXEC, 0); 797 goto done2; 798 } 799 800 exec_fail: 801 /* we're done here, clear P_INEXEC */ 802 PROC_LOCK(p); 803 p->p_flag &= ~P_INEXEC; 804 PROC_UNLOCK(p); 805 806 if (imgp->vmspace_destroyed) { 807 /* sorry, no more process anymore. exit gracefully */ 808 #ifdef MAC 809 mac_execve_exit(imgp); 810 if (interplabel != NULL) 811 mac_vnode_label_free(interplabel); 812 #endif 813 VFS_UNLOCK_GIANT(vfslocked); 814 exec_free_args(args); 815 exit1(td, W_EXITCODE(0, SIGABRT)); 816 /* NOT REACHED */ 817 error = 0; 818 } 819 done2: 820 #ifdef MAC 821 mac_execve_exit(imgp); 822 if (interplabel != NULL) 823 mac_vnode_label_free(interplabel); 824 #endif 825 VFS_UNLOCK_GIANT(vfslocked); 826 return (error); 827 } 828 829 int 830 exec_map_first_page(imgp) 831 struct image_params *imgp; 832 { 833 int rv, i; 834 int initial_pagein; 835 vm_page_t ma[VM_INITIAL_PAGEIN]; 836 vm_object_t object; 837 838 if (imgp->firstpage != NULL) 839 exec_unmap_first_page(imgp); 840 841 object = imgp->vp->v_object; 842 if (object == NULL) 843 return (EACCES); 844 VM_OBJECT_LOCK(object); 845 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 846 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 847 initial_pagein = VM_INITIAL_PAGEIN; 848 if (initial_pagein > object->size) 849 initial_pagein = object->size; 850 for (i = 1; i < initial_pagein; i++) { 851 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 852 if (ma[i]->valid) 853 break; 854 vm_page_lock_queues(); 855 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy) { 856 vm_page_unlock_queues(); 857 break; 858 } 859 vm_page_busy(ma[i]); 860 vm_page_unlock_queues(); 861 } else { 862 ma[i] = vm_page_alloc(object, i, 863 VM_ALLOC_NORMAL); 864 if (ma[i] == NULL) 865 break; 866 } 867 } 868 initial_pagein = i; 869 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 870 ma[0] = vm_page_lookup(object, 0); 871 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || 872 (ma[0]->valid == 0)) { 873 if (ma[0]) { 874 vm_page_lock_queues(); 875 pmap_remove_all(ma[0]); 876 vm_page_free(ma[0]); 877 vm_page_unlock_queues(); 878 } 879 VM_OBJECT_UNLOCK(object); 880 return (EIO); 881 } 882 } 883 vm_page_lock_queues(); 884 vm_page_hold(ma[0]); 885 vm_page_wakeup(ma[0]); 886 vm_page_unlock_queues(); 887 VM_OBJECT_UNLOCK(object); 888 889 imgp->firstpage = sf_buf_alloc(ma[0], 0); 890 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 891 892 return (0); 893 } 894 895 void 896 exec_unmap_first_page(imgp) 897 struct image_params *imgp; 898 { 899 vm_page_t m; 900 901 if (imgp->firstpage != NULL) { 902 m = sf_buf_page(imgp->firstpage); 903 sf_buf_free(imgp->firstpage); 904 imgp->firstpage = NULL; 905 vm_page_lock_queues(); 906 vm_page_unhold(m); 907 vm_page_unlock_queues(); 908 } 909 } 910 911 /* 912 * Destroy old address space, and allocate a new stack 913 * The new stack is only SGROWSIZ large because it is grown 914 * automatically in trap.c. 915 */ 916 int 917 exec_new_vmspace(imgp, sv) 918 struct image_params *imgp; 919 struct sysentvec *sv; 920 { 921 int error; 922 struct proc *p = imgp->proc; 923 struct vmspace *vmspace = p->p_vmspace; 924 vm_offset_t sv_minuser, stack_addr; 925 vm_map_t map; 926 927 imgp->vmspace_destroyed = 1; 928 929 /* Called with Giant held, do not depend on it! */ 930 EVENTHANDLER_INVOKE(process_exec, p); 931 932 /* 933 * Blow away entire process VM, if address space not shared, 934 * otherwise, create a new VM space so that other threads are 935 * not disrupted 936 */ 937 map = &vmspace->vm_map; 938 if (map_at_zero) 939 sv_minuser = sv->sv_minuser; 940 else 941 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 942 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 943 vm_map_max(map) == sv->sv_maxuser) { 944 shmexit(vmspace); 945 pmap_remove_pages(vmspace_pmap(vmspace), vm_map_min(map), 946 vm_map_max(map)); 947 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 948 } else { 949 vmspace_exec(p, sv_minuser, sv->sv_maxuser); 950 vmspace = p->p_vmspace; 951 map = &vmspace->vm_map; 952 } 953 954 /* Allocate a new stack */ 955 stack_addr = sv->sv_usrstack - maxssiz; 956 error = vm_map_stack(map, stack_addr, (vm_size_t)maxssiz, 957 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 958 if (error) 959 return (error); 960 961 #ifdef __ia64__ 962 /* Allocate a new register stack */ 963 stack_addr = IA64_BACKINGSTORE; 964 error = vm_map_stack(map, stack_addr, (vm_size_t)maxssiz, 965 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP); 966 if (error) 967 return (error); 968 #endif 969 970 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 971 * VM_STACK case, but they are still used to monitor the size of the 972 * process stack so we can check the stack rlimit. 973 */ 974 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 975 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - maxssiz; 976 977 return (0); 978 } 979 980 /* 981 * Copy out argument and environment strings from the old process 982 * address space into the temporary string buffer. 983 */ 984 int 985 exec_copyin_args(struct image_args *args, char *fname, 986 enum uio_seg segflg, char **argv, char **envv) 987 { 988 char *argp, *envp; 989 int error; 990 size_t length; 991 992 error = 0; 993 994 bzero(args, sizeof(*args)); 995 if (argv == NULL) 996 return (EFAULT); 997 /* 998 * Allocate temporary demand zeroed space for argument and 999 * environment strings: 1000 * 1001 * o ARG_MAX for argument and environment; 1002 * o MAXSHELLCMDLEN for the name of interpreters. 1003 */ 1004 args->buf = (char *) kmem_alloc_wait(exec_map, 1005 PATH_MAX + ARG_MAX + MAXSHELLCMDLEN); 1006 if (args->buf == NULL) 1007 return (ENOMEM); 1008 args->begin_argv = args->buf; 1009 args->endp = args->begin_argv; 1010 args->stringspace = ARG_MAX; 1011 1012 args->fname = args->buf + ARG_MAX; 1013 1014 /* 1015 * Copy the file name. 1016 */ 1017 error = (segflg == UIO_SYSSPACE) ? 1018 copystr(fname, args->fname, PATH_MAX, &length) : 1019 copyinstr(fname, args->fname, PATH_MAX, &length); 1020 if (error != 0) 1021 return (error); 1022 1023 /* 1024 * extract arguments first 1025 */ 1026 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 1027 if (argp == (caddr_t) -1) 1028 return (EFAULT); 1029 if ((error = copyinstr(argp, args->endp, 1030 args->stringspace, &length))) { 1031 if (error == ENAMETOOLONG) 1032 return (E2BIG); 1033 return (error); 1034 } 1035 args->stringspace -= length; 1036 args->endp += length; 1037 args->argc++; 1038 } 1039 1040 args->begin_envv = args->endp; 1041 1042 /* 1043 * extract environment strings 1044 */ 1045 if (envv) { 1046 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) { 1047 if (envp == (caddr_t)-1) 1048 return (EFAULT); 1049 if ((error = copyinstr(envp, args->endp, 1050 args->stringspace, &length))) { 1051 if (error == ENAMETOOLONG) 1052 return (E2BIG); 1053 return (error); 1054 } 1055 args->stringspace -= length; 1056 args->endp += length; 1057 args->envc++; 1058 } 1059 } 1060 1061 return (0); 1062 } 1063 1064 void 1065 exec_free_args(struct image_args *args) 1066 { 1067 1068 if (args->buf) { 1069 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf, 1070 PATH_MAX + ARG_MAX + MAXSHELLCMDLEN); 1071 args->buf = NULL; 1072 } 1073 } 1074 1075 /* 1076 * Copy strings out to the new process address space, constructing 1077 * new arg and env vector tables. Return a pointer to the base 1078 * so that it can be used as the initial stack pointer. 1079 */ 1080 register_t * 1081 exec_copyout_strings(imgp) 1082 struct image_params *imgp; 1083 { 1084 int argc, envc; 1085 char **vectp; 1086 char *stringp, *destp; 1087 register_t *stack_base; 1088 struct ps_strings *arginfo; 1089 struct proc *p; 1090 int szsigcode; 1091 1092 /* 1093 * Calculate string base and vector table pointers. 1094 * Also deal with signal trampoline code for this exec type. 1095 */ 1096 p = imgp->proc; 1097 szsigcode = 0; 1098 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1099 if (p->p_sysent->sv_szsigcode != NULL) 1100 szsigcode = *(p->p_sysent->sv_szsigcode); 1101 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 1102 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *)); 1103 1104 /* 1105 * install sigcode 1106 */ 1107 if (szsigcode) 1108 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo - 1109 szsigcode), szsigcode); 1110 1111 /* 1112 * If we have a valid auxargs ptr, prepare some room 1113 * on the stack. 1114 */ 1115 if (imgp->auxargs) { 1116 /* 1117 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1118 * lower compatibility. 1119 */ 1120 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1121 (AT_COUNT * 2); 1122 /* 1123 * The '+ 2' is for the null pointers at the end of each of 1124 * the arg and env vector sets,and imgp->auxarg_size is room 1125 * for argument of Runtime loader. 1126 */ 1127 vectp = (char **)(destp - (imgp->args->argc + 1128 imgp->args->envc + 2 + imgp->auxarg_size) * 1129 sizeof(char *)); 1130 1131 } else { 1132 /* 1133 * The '+ 2' is for the null pointers at the end of each of 1134 * the arg and env vector sets 1135 */ 1136 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) * 1137 sizeof(char *)); 1138 } 1139 1140 /* 1141 * vectp also becomes our initial stack base 1142 */ 1143 stack_base = (register_t *)vectp; 1144 1145 stringp = imgp->args->begin_argv; 1146 argc = imgp->args->argc; 1147 envc = imgp->args->envc; 1148 1149 /* 1150 * Copy out strings - arguments and environment. 1151 */ 1152 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace); 1153 1154 /* 1155 * Fill in "ps_strings" struct for ps, w, etc. 1156 */ 1157 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1158 suword(&arginfo->ps_nargvstr, argc); 1159 1160 /* 1161 * Fill in argument portion of vector table. 1162 */ 1163 for (; argc > 0; --argc) { 1164 suword(vectp++, (long)(intptr_t)destp); 1165 while (*stringp++ != 0) 1166 destp++; 1167 destp++; 1168 } 1169 1170 /* a null vector table pointer separates the argp's from the envp's */ 1171 suword(vectp++, 0); 1172 1173 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1174 suword(&arginfo->ps_nenvstr, envc); 1175 1176 /* 1177 * Fill in environment portion of vector table. 1178 */ 1179 for (; envc > 0; --envc) { 1180 suword(vectp++, (long)(intptr_t)destp); 1181 while (*stringp++ != 0) 1182 destp++; 1183 destp++; 1184 } 1185 1186 /* end of vector table is a null pointer */ 1187 suword(vectp, 0); 1188 1189 return (stack_base); 1190 } 1191 1192 /* 1193 * Check permissions of file to execute. 1194 * Called with imgp->vp locked. 1195 * Return 0 for success or error code on failure. 1196 */ 1197 int 1198 exec_check_permissions(imgp) 1199 struct image_params *imgp; 1200 { 1201 struct vnode *vp = imgp->vp; 1202 struct vattr *attr = imgp->attr; 1203 struct thread *td; 1204 int error; 1205 1206 td = curthread; /* XXXKSE */ 1207 1208 /* Get file attributes */ 1209 error = VOP_GETATTR(vp, attr, td->td_ucred, td); 1210 if (error) 1211 return (error); 1212 1213 #ifdef MAC 1214 error = mac_check_vnode_exec(td->td_ucred, imgp->vp, imgp); 1215 if (error) 1216 return (error); 1217 #endif 1218 1219 /* 1220 * 1) Check if file execution is disabled for the filesystem that this 1221 * file resides on. 1222 * 2) Insure that at least one execute bit is on - otherwise root 1223 * will always succeed, and we don't want to happen unless the 1224 * file really is executable. 1225 * 3) Insure that the file is a regular file. 1226 */ 1227 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1228 ((attr->va_mode & 0111) == 0) || 1229 (attr->va_type != VREG)) 1230 return (EACCES); 1231 1232 /* 1233 * Zero length files can't be exec'd 1234 */ 1235 if (attr->va_size == 0) 1236 return (ENOEXEC); 1237 1238 /* 1239 * Check for execute permission to file based on current credentials. 1240 */ 1241 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1242 if (error) 1243 return (error); 1244 1245 /* 1246 * Check number of open-for-writes on the file and deny execution 1247 * if there are any. 1248 */ 1249 if (vp->v_writecount) 1250 return (ETXTBSY); 1251 1252 /* 1253 * Call filesystem specific open routine (which does nothing in the 1254 * general case). 1255 */ 1256 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, -1); 1257 return (error); 1258 } 1259 1260 /* 1261 * Exec handler registration 1262 */ 1263 int 1264 exec_register(execsw_arg) 1265 const struct execsw *execsw_arg; 1266 { 1267 const struct execsw **es, **xs, **newexecsw; 1268 int count = 2; /* New slot and trailing NULL */ 1269 1270 if (execsw) 1271 for (es = execsw; *es; es++) 1272 count++; 1273 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1274 if (newexecsw == NULL) 1275 return (ENOMEM); 1276 xs = newexecsw; 1277 if (execsw) 1278 for (es = execsw; *es; es++) 1279 *xs++ = *es; 1280 *xs++ = execsw_arg; 1281 *xs = NULL; 1282 if (execsw) 1283 free(execsw, M_TEMP); 1284 execsw = newexecsw; 1285 return (0); 1286 } 1287 1288 int 1289 exec_unregister(execsw_arg) 1290 const struct execsw *execsw_arg; 1291 { 1292 const struct execsw **es, **xs, **newexecsw; 1293 int count = 1; 1294 1295 if (execsw == NULL) 1296 panic("unregister with no handlers left?\n"); 1297 1298 for (es = execsw; *es; es++) { 1299 if (*es == execsw_arg) 1300 break; 1301 } 1302 if (*es == NULL) 1303 return (ENOENT); 1304 for (es = execsw; *es; es++) 1305 if (*es != execsw_arg) 1306 count++; 1307 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1308 if (newexecsw == NULL) 1309 return (ENOMEM); 1310 xs = newexecsw; 1311 for (es = execsw; *es; es++) 1312 if (*es != execsw_arg) 1313 *xs++ = *es; 1314 *xs = NULL; 1315 if (execsw) 1316 free(execsw, M_TEMP); 1317 execsw = newexecsw; 1318 return (0); 1319 }
Cache object: 238863ddd6e8c3bfdc1257b4a0ec188b
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