Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_exec.c
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1 /*- 2 * Copyright (c) 1993, David Greenman 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD: releng/7.3/sys/kern/kern_exec.c 202765 2010-01-21 19:17:42Z jhb $"); 29 30 #include "opt_hwpmc_hooks.h" 31 #include "opt_kdtrace.h" 32 #include "opt_ktrace.h" 33 #include "opt_mac.h" 34 #include "opt_vm.h" 35 36 #include <sys/param.h> 37 #include <sys/systm.h> 38 #include <sys/eventhandler.h> 39 #include <sys/lock.h> 40 #include <sys/mutex.h> 41 #include <sys/sysproto.h> 42 #include <sys/signalvar.h> 43 #include <sys/kernel.h> 44 #include <sys/mount.h> 45 #include <sys/filedesc.h> 46 #include <sys/fcntl.h> 47 #include <sys/acct.h> 48 #include <sys/exec.h> 49 #include <sys/imgact.h> 50 #include <sys/imgact_elf.h> 51 #include <sys/wait.h> 52 #include <sys/malloc.h> 53 #include <sys/priv.h> 54 #include <sys/proc.h> 55 #include <sys/pioctl.h> 56 #include <sys/namei.h> 57 #include <sys/resourcevar.h> 58 #include <sys/sdt.h> 59 #include <sys/sf_buf.h> 60 #include <sys/syscallsubr.h> 61 #include <sys/sysent.h> 62 #include <sys/shm.h> 63 #include <sys/sysctl.h> 64 #include <sys/vnode.h> 65 #ifdef KTRACE 66 #include <sys/ktrace.h> 67 #endif 68 69 #include <vm/vm.h> 70 #include <vm/vm_param.h> 71 #include <vm/pmap.h> 72 #include <vm/vm_page.h> 73 #include <vm/vm_map.h> 74 #include <vm/vm_kern.h> 75 #include <vm/vm_extern.h> 76 #include <vm/vm_object.h> 77 #include <vm/vm_pager.h> 78 79 #ifdef HWPMC_HOOKS 80 #include <sys/pmckern.h> 81 #endif 82 83 #include <machine/reg.h> 84 85 #include <security/audit/audit.h> 86 #include <security/mac/mac_framework.h> 87 88 #ifdef KDTRACE_HOOKS 89 #include <sys/dtrace_bsd.h> 90 dtrace_execexit_func_t dtrace_fasttrap_exec; 91 #endif 92 93 SDT_PROVIDER_DECLARE(proc); 94 SDT_PROBE_DEFINE(proc, kernel, , exec); 95 SDT_PROBE_ARGTYPE(proc, kernel, , exec, 0, "char *"); 96 SDT_PROBE_DEFINE(proc, kernel, , exec_failure); 97 SDT_PROBE_ARGTYPE(proc, kernel, , exec_failure, 0, "int"); 98 SDT_PROBE_DEFINE(proc, kernel, , exec_success); 99 SDT_PROBE_ARGTYPE(proc, kernel, , exec_success, 0, "char *"); 100 101 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 102 103 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 104 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 105 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 106 static int do_execve(struct thread *td, struct image_args *args, 107 struct mac *mac_p); 108 static void exec_free_args(struct image_args *); 109 110 /* XXX This should be vm_size_t. */ 111 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD, 112 NULL, 0, sysctl_kern_ps_strings, "LU", ""); 113 114 /* XXX This should be vm_size_t. */ 115 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD, 116 NULL, 0, sysctl_kern_usrstack, "LU", ""); 117 118 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 119 NULL, 0, sysctl_kern_stackprot, "I", ""); 120 121 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 122 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 123 &ps_arg_cache_limit, 0, ""); 124 125 static int map_at_zero = 1; 126 TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero); 127 SYSCTL_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."); 129 130 static int 131 sysctl_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 } 148 149 static int 150 sysctl_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 } 167 168 static int 169 sysctl_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 */ 182 static const struct execsw **execsw; 183 184 #ifndef _SYS_SYSPROTO_H_ 185 struct execve_args { 186 char *fname; 187 char **argv; 188 char **envv; 189 }; 190 #endif 191 192 int 193 execve(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_ 212 struct __mac_execve_args { 213 char *fname; 214 char **argv; 215 char **envv; 216 struct mac *mac_p; 217 }; 218 #endif 219 220 int 221 __mac_execve(td, uap) 222 struct thread *td; 223 struct __mac_execve_args /* { 224 char *fname; 225 char **argv; 226 char **envv; 227 struct mac *mac_p; 228 } */ *uap; 229 { 230 #ifdef MAC 231 int error; 232 struct image_args args; 233 234 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 235 uap->argv, uap->envv); 236 if (error == 0) 237 error = kern_execve(td, &args, uap->mac_p); 238 return (error); 239 #else 240 return (ENOSYS); 241 #endif 242 } 243 244 /* 245 * XXX: kern_execve has the astonishing property of not always returning to 246 * the caller. If sufficiently bad things happen during the call to 247 * do_execve(), it can end up calling exit1(); as a result, callers must 248 * avoid doing anything which they might need to undo (e.g., allocating 249 * memory). 250 */ 251 int 252 kern_execve(td, args, mac_p) 253 struct thread *td; 254 struct image_args *args; 255 struct mac *mac_p; 256 { 257 struct proc *p = td->td_proc; 258 int error; 259 260 AUDIT_ARG(argv, args->begin_argv, args->argc, 261 args->begin_envv - args->begin_argv); 262 AUDIT_ARG(envv, args->begin_envv, args->envc, 263 args->endp - args->begin_envv); 264 if (p->p_flag & P_HADTHREADS) { 265 PROC_LOCK(p); 266 if (thread_single(SINGLE_BOUNDARY)) { 267 PROC_UNLOCK(p); 268 exec_free_args(args); 269 return (ERESTART); /* Try again later. */ 270 } 271 PROC_UNLOCK(p); 272 } 273 274 error = do_execve(td, args, mac_p); 275 276 if (p->p_flag & P_HADTHREADS) { 277 PROC_LOCK(p); 278 /* 279 * If success, we upgrade to SINGLE_EXIT state to 280 * force other threads to suicide. 281 */ 282 if (error == 0) 283 thread_single(SINGLE_EXIT); 284 else 285 thread_single_end(); 286 PROC_UNLOCK(p); 287 } 288 289 return (error); 290 } 291 292 /* 293 * In-kernel implementation of execve(). All arguments are assumed to be 294 * userspace pointers from the passed thread. 295 */ 296 static int 297 do_execve(td, args, mac_p) 298 struct thread *td; 299 struct image_args *args; 300 struct mac *mac_p; 301 { 302 struct proc *p = td->td_proc; 303 struct nameidata nd, *ndp; 304 struct ucred *newcred = NULL, *oldcred; 305 struct uidinfo *euip; 306 register_t *stack_base; 307 int error, len, i; 308 struct image_params image_params, *imgp; 309 struct vattr attr; 310 int (*img_first)(struct image_params *); 311 struct pargs *oldargs = NULL, *newargs = NULL; 312 struct sigacts *oldsigacts, *newsigacts; 313 #ifdef KTRACE 314 struct vnode *tracevp = NULL; 315 struct ucred *tracecred = NULL; 316 #endif 317 struct vnode *textvp = NULL; 318 int credential_changing; 319 int vfslocked; 320 int textset; 321 #ifdef MAC 322 struct label *interplabel = NULL; 323 int will_transition; 324 #endif 325 #ifdef HWPMC_HOOKS 326 struct pmckern_procexec pe; 327 #endif 328 329 vfslocked = 0; 330 imgp = &image_params; 331 332 /* 333 * Lock the process and set the P_INEXEC flag to indicate that 334 * it should be left alone until we're done here. This is 335 * necessary to avoid race conditions - e.g. in ptrace() - 336 * that might allow a local user to illicitly obtain elevated 337 * privileges. 338 */ 339 PROC_LOCK(p); 340 KASSERT((p->p_flag & P_INEXEC) == 0, 341 ("%s(): process already has P_INEXEC flag", __func__)); 342 p->p_flag |= P_INEXEC; 343 PROC_UNLOCK(p); 344 345 /* 346 * Initialize part of the common data 347 */ 348 imgp->proc = p; 349 imgp->execlabel = NULL; 350 imgp->attr = &attr; 351 imgp->entry_addr = 0; 352 imgp->vmspace_destroyed = 0; 353 imgp->interpreted = 0; 354 imgp->opened = 0; 355 imgp->interpreter_name = args->buf + PATH_MAX + ARG_MAX; 356 imgp->auxargs = NULL; 357 imgp->vp = NULL; 358 imgp->object = NULL; 359 imgp->firstpage = NULL; 360 imgp->ps_strings = 0; 361 imgp->auxarg_size = 0; 362 imgp->args = args; 363 imgp->execpath = imgp->freepath = NULL; 364 imgp->execpathp = 0; 365 366 #ifdef MAC 367 error = mac_execve_enter(imgp, mac_p); 368 if (error) 369 goto exec_fail; 370 #endif 371 372 imgp->image_header = NULL; 373 374 /* 375 * Translate the file name. namei() returns a vnode pointer 376 * in ni_vp amoung other things. 377 * 378 * XXXAUDIT: It would be desirable to also audit the name of the 379 * interpreter if this is an interpreted binary. 380 */ 381 ndp = &nd; 382 NDINIT(ndp, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME | MPSAFE | 383 AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 384 385 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 386 387 interpret: 388 error = namei(ndp); 389 if (error) 390 goto exec_fail; 391 392 vfslocked = NDHASGIANT(ndp); 393 imgp->vp = ndp->ni_vp; 394 395 /* 396 * Check file permissions (also 'opens' file) 397 */ 398 error = exec_check_permissions(imgp); 399 if (error) 400 goto exec_fail_dealloc; 401 402 imgp->object = imgp->vp->v_object; 403 if (imgp->object != NULL) 404 vm_object_reference(imgp->object); 405 406 /* 407 * Set VV_TEXT now so no one can write to the executable while we're 408 * activating it. 409 * 410 * Remember if this was set before and unset it in case this is not 411 * actually an executable image. 412 */ 413 textset = imgp->vp->v_vflag & VV_TEXT; 414 imgp->vp->v_vflag |= VV_TEXT; 415 416 error = exec_map_first_page(imgp); 417 if (error) 418 goto exec_fail_dealloc; 419 420 imgp->proc->p_osrel = 0; 421 /* 422 * If the current process has a special image activator it 423 * wants to try first, call it. For example, emulating shell 424 * scripts differently. 425 */ 426 error = -1; 427 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 428 error = img_first(imgp); 429 430 /* 431 * Loop through the list of image activators, calling each one. 432 * An activator returns -1 if there is no match, 0 on success, 433 * and an error otherwise. 434 */ 435 for (i = 0; error == -1 && execsw[i]; ++i) { 436 if (execsw[i]->ex_imgact == NULL || 437 execsw[i]->ex_imgact == img_first) { 438 continue; 439 } 440 error = (*execsw[i]->ex_imgact)(imgp); 441 } 442 443 if (error) { 444 if (error == -1) { 445 if (textset == 0) 446 imgp->vp->v_vflag &= ~VV_TEXT; 447 error = ENOEXEC; 448 } 449 goto exec_fail_dealloc; 450 } 451 452 /* 453 * Special interpreter operation, cleanup and loop up to try to 454 * activate the interpreter. 455 */ 456 if (imgp->interpreted) { 457 exec_unmap_first_page(imgp); 458 /* 459 * VV_TEXT needs to be unset for scripts. There is a short 460 * period before we determine that something is a script where 461 * VV_TEXT will be set. The vnode lock is held over this 462 * entire period so nothing should illegitimately be blocked. 463 */ 464 imgp->vp->v_vflag &= ~VV_TEXT; 465 /* free name buffer and old vnode */ 466 NDFREE(ndp, NDF_ONLY_PNBUF); 467 #ifdef MAC 468 interplabel = mac_vnode_label_alloc(); 469 mac_copy_vnode_label(ndp->ni_vp->v_label, interplabel); 470 #endif 471 if (imgp->opened) { 472 VOP_CLOSE(ndp->ni_vp, FREAD, td->td_ucred, td); 473 imgp->opened = 0; 474 } 475 vput(ndp->ni_vp); 476 vm_object_deallocate(imgp->object); 477 imgp->object = NULL; 478 VFS_UNLOCK_GIANT(vfslocked); 479 vfslocked = 0; 480 /* set new name to that of the interpreter */ 481 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME | MPSAFE, 482 UIO_SYSSPACE, imgp->interpreter_name, td); 483 goto interpret; 484 } 485 486 /* 487 * NB: We unlock the vnode here because it is believed that none 488 * of the sv_copyout_strings/sv_fixup operations require the vnode. 489 */ 490 VOP_UNLOCK(imgp->vp, 0, td); 491 492 if (imgp->auxargs != NULL) 493 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath); 494 495 /* 496 * Copy out strings (args and env) and initialize stack base 497 */ 498 if (p->p_sysent->sv_copyout_strings) 499 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 500 else 501 stack_base = exec_copyout_strings(imgp); 502 503 /* 504 * If custom stack fixup routine present for this process 505 * let it do the stack setup. 506 * Else stuff argument count as first item on stack 507 */ 508 if (p->p_sysent->sv_fixup != NULL) 509 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 510 else 511 suword(--stack_base, imgp->args->argc); 512 513 /* 514 * For security and other reasons, the file descriptor table cannot 515 * be shared after an exec. 516 */ 517 fdunshare(p, td); 518 519 /* 520 * Malloc things before we need locks. 521 */ 522 newcred = crget(); 523 euip = uifind(attr.va_uid); 524 i = imgp->args->begin_envv - imgp->args->begin_argv; 525 /* Cache arguments if they fit inside our allowance */ 526 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 527 newargs = pargs_alloc(i); 528 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 529 } 530 531 /* close files on exec */ 532 fdcloseexec(td); 533 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY, td); 534 535 /* Get a reference to the vnode prior to locking the proc */ 536 VREF(ndp->ni_vp); 537 538 /* 539 * For security and other reasons, signal handlers cannot 540 * be shared after an exec. The new process gets a copy of the old 541 * handlers. In execsigs(), the new process will have its signals 542 * reset. 543 */ 544 PROC_LOCK(p); 545 if (sigacts_shared(p->p_sigacts)) { 546 oldsigacts = p->p_sigacts; 547 PROC_UNLOCK(p); 548 newsigacts = sigacts_alloc(); 549 sigacts_copy(newsigacts, oldsigacts); 550 PROC_LOCK(p); 551 p->p_sigacts = newsigacts; 552 } else 553 oldsigacts = NULL; 554 555 /* Stop profiling */ 556 stopprofclock(p); 557 558 /* reset caught signals */ 559 execsigs(p); 560 561 /* name this process - nameiexec(p, ndp) */ 562 bzero(p->p_comm, sizeof(p->p_comm)); 563 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 564 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 565 566 /* 567 * mark as execed, wakeup the process that vforked (if any) and tell 568 * it that it now has its own resources back 569 */ 570 p->p_flag |= P_EXEC; 571 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 572 p->p_flag &= ~P_PPWAIT; 573 cv_broadcast(&p->p_pwait); 574 } 575 576 /* 577 * Implement image setuid/setgid. 578 * 579 * Don't honor setuid/setgid if the filesystem prohibits it or if 580 * the process is being traced. 581 * 582 * XXXMAC: For the time being, use NOSUID to also prohibit 583 * transitions on the file system. 584 */ 585 oldcred = p->p_ucred; 586 credential_changing = 0; 587 credential_changing |= (attr.va_mode & VSUID) && oldcred->cr_uid != 588 attr.va_uid; 589 credential_changing |= (attr.va_mode & VSGID) && oldcred->cr_gid != 590 attr.va_gid; 591 #ifdef MAC 592 will_transition = mac_execve_will_transition(oldcred, imgp->vp, 593 interplabel, imgp); 594 credential_changing |= will_transition; 595 #endif 596 597 if (credential_changing && 598 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 599 (p->p_flag & P_TRACED) == 0) { 600 /* 601 * Turn off syscall tracing for set-id programs, except for 602 * root. Record any set-id flags first to make sure that 603 * we do not regain any tracing during a possible block. 604 */ 605 setsugid(p); 606 607 #ifdef KTRACE 608 if (p->p_tracevp != NULL && 609 priv_check_cred(oldcred, PRIV_DEBUG_DIFFCRED, 0)) { 610 mtx_lock(&ktrace_mtx); 611 p->p_traceflag = 0; 612 tracevp = p->p_tracevp; 613 p->p_tracevp = NULL; 614 tracecred = p->p_tracecred; 615 p->p_tracecred = NULL; 616 mtx_unlock(&ktrace_mtx); 617 } 618 #endif 619 /* 620 * Close any file descriptors 0..2 that reference procfs, 621 * then make sure file descriptors 0..2 are in use. 622 * 623 * setugidsafety() may call closef() and then pfind() 624 * which may grab the process lock. 625 * fdcheckstd() may call falloc() which may block to 626 * allocate memory, so temporarily drop the process lock. 627 */ 628 PROC_UNLOCK(p); 629 VOP_UNLOCK(imgp->vp, 0, td); 630 setugidsafety(td); 631 error = fdcheckstd(td); 632 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY, td); 633 if (error != 0) 634 goto done1; 635 PROC_LOCK(p); 636 /* 637 * Set the new credentials. 638 */ 639 crcopy(newcred, oldcred); 640 if (attr.va_mode & VSUID) 641 change_euid(newcred, euip); 642 if (attr.va_mode & VSGID) 643 change_egid(newcred, attr.va_gid); 644 #ifdef MAC 645 if (will_transition) { 646 mac_execve_transition(oldcred, newcred, imgp->vp, 647 interplabel, imgp); 648 } 649 #endif 650 /* 651 * Implement correct POSIX saved-id behavior. 652 * 653 * XXXMAC: Note that the current logic will save the 654 * uid and gid if a MAC domain transition occurs, even 655 * though maybe it shouldn't. 656 */ 657 change_svuid(newcred, newcred->cr_uid); 658 change_svgid(newcred, newcred->cr_gid); 659 p->p_ucred = newcred; 660 newcred = NULL; 661 } else { 662 if (oldcred->cr_uid == oldcred->cr_ruid && 663 oldcred->cr_gid == oldcred->cr_rgid) 664 p->p_flag &= ~P_SUGID; 665 /* 666 * Implement correct POSIX saved-id behavior. 667 * 668 * XXX: It's not clear that the existing behavior is 669 * POSIX-compliant. A number of sources indicate that the 670 * saved uid/gid should only be updated if the new ruid is 671 * not equal to the old ruid, or the new euid is not equal 672 * to the old euid and the new euid is not equal to the old 673 * ruid. The FreeBSD code always updates the saved uid/gid. 674 * Also, this code uses the new (replaced) euid and egid as 675 * the source, which may or may not be the right ones to use. 676 */ 677 if (oldcred->cr_svuid != oldcred->cr_uid || 678 oldcred->cr_svgid != oldcred->cr_gid) { 679 crcopy(newcred, oldcred); 680 change_svuid(newcred, newcred->cr_uid); 681 change_svgid(newcred, newcred->cr_gid); 682 p->p_ucred = newcred; 683 newcred = NULL; 684 } 685 } 686 687 /* 688 * Store the vp for use in procfs. This vnode was referenced prior 689 * to locking the proc lock. 690 */ 691 textvp = p->p_textvp; 692 p->p_textvp = ndp->ni_vp; 693 694 #ifdef KDTRACE_HOOKS 695 /* 696 * Tell the DTrace fasttrap provider about the exec if it 697 * has declared an interest. 698 */ 699 if (dtrace_fasttrap_exec) 700 dtrace_fasttrap_exec(p); 701 #endif 702 703 /* 704 * Notify others that we exec'd, and clear the P_INEXEC flag 705 * as we're now a bona fide freshly-execed process. 706 */ 707 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 708 p->p_flag &= ~P_INEXEC; 709 710 /* 711 * If tracing the process, trap to debugger so breakpoints 712 * can be set before the program executes. 713 * Use tdsignal to deliver signal to current thread, use 714 * psignal may cause the signal to be delivered to wrong thread 715 * because that thread will exit, remember we are going to enter 716 * single thread mode. 717 */ 718 if (p->p_flag & P_TRACED) 719 tdsignal(p, td, SIGTRAP, NULL); 720 721 /* clear "fork but no exec" flag, as we _are_ execing */ 722 p->p_acflag &= ~AFORK; 723 724 /* 725 * Free any previous argument cache and replace it with 726 * the new argument cache, if any. 727 */ 728 oldargs = p->p_args; 729 p->p_args = newargs; 730 newargs = NULL; 731 732 #ifdef HWPMC_HOOKS 733 /* 734 * Check if system-wide sampling is in effect or if the 735 * current process is using PMCs. If so, do exec() time 736 * processing. This processing needs to happen AFTER the 737 * P_INEXEC flag is cleared. 738 * 739 * The proc lock needs to be released before taking the PMC 740 * SX. 741 */ 742 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 743 PROC_UNLOCK(p); 744 pe.pm_credentialschanged = credential_changing; 745 pe.pm_entryaddr = imgp->entry_addr; 746 747 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 748 } else 749 PROC_UNLOCK(p); 750 #else /* !HWPMC_HOOKS */ 751 PROC_UNLOCK(p); 752 #endif 753 754 /* Set values passed into the program in registers. */ 755 if (p->p_sysent->sv_setregs) 756 (*p->p_sysent->sv_setregs)(td, imgp->entry_addr, 757 (u_long)(uintptr_t)stack_base, imgp->ps_strings); 758 else 759 exec_setregs(td, imgp->entry_addr, 760 (u_long)(uintptr_t)stack_base, imgp->ps_strings); 761 762 vfs_mark_atime(imgp->vp, td); 763 764 SDT_PROBE(proc, kernel, , exec_success, args->fname, 0, 0, 0, 0); 765 done1: 766 /* 767 * Free any resources malloc'd earlier that we didn't use. 768 */ 769 uifree(euip); 770 if (newcred == NULL) 771 crfree(oldcred); 772 else 773 crfree(newcred); 774 VOP_UNLOCK(imgp->vp, 0, td); 775 776 /* 777 * Handle deferred decrement of ref counts. 778 */ 779 if (textvp != NULL) { 780 int tvfslocked; 781 782 tvfslocked = VFS_LOCK_GIANT(textvp->v_mount); 783 vrele(textvp); 784 VFS_UNLOCK_GIANT(tvfslocked); 785 } 786 if (ndp->ni_vp && error != 0) 787 vrele(ndp->ni_vp); 788 #ifdef KTRACE 789 if (tracevp != NULL) { 790 int tvfslocked; 791 792 tvfslocked = VFS_LOCK_GIANT(tracevp->v_mount); 793 vrele(tracevp); 794 VFS_UNLOCK_GIANT(tvfslocked); 795 } 796 if (tracecred != NULL) 797 crfree(tracecred); 798 #endif 799 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY, td); 800 pargs_drop(oldargs); 801 pargs_drop(newargs); 802 if (oldsigacts != NULL) 803 sigacts_free(oldsigacts); 804 805 exec_fail_dealloc: 806 807 /* 808 * free various allocated resources 809 */ 810 if (imgp->firstpage != NULL) 811 exec_unmap_first_page(imgp); 812 813 if (imgp->vp != NULL) { 814 NDFREE(ndp, NDF_ONLY_PNBUF); 815 if (imgp->opened) 816 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 817 vput(imgp->vp); 818 } 819 820 if (imgp->object != NULL) 821 vm_object_deallocate(imgp->object); 822 823 free(imgp->freepath, M_TEMP); 824 825 if (error == 0) { 826 /* 827 * Stop the process here if its stop event mask has 828 * the S_EXEC bit set. 829 */ 830 STOPEVENT(p, S_EXEC, 0); 831 goto done2; 832 } 833 834 exec_fail: 835 /* we're done here, clear P_INEXEC */ 836 PROC_LOCK(p); 837 p->p_flag &= ~P_INEXEC; 838 PROC_UNLOCK(p); 839 840 SDT_PROBE(proc, kernel, , exec_failure, error, 0, 0, 0, 0); 841 842 done2: 843 #ifdef MAC 844 mac_execve_exit(imgp); 845 if (interplabel != NULL) 846 mac_vnode_label_free(interplabel); 847 #endif 848 VFS_UNLOCK_GIANT(vfslocked); 849 exec_free_args(args); 850 851 if (error && imgp->vmspace_destroyed) { 852 /* sorry, no more process anymore. exit gracefully */ 853 exit1(td, W_EXITCODE(0, SIGABRT)); 854 /* NOT REACHED */ 855 } 856 return (error); 857 } 858 859 int 860 exec_map_first_page(imgp) 861 struct image_params *imgp; 862 { 863 int rv, i; 864 int initial_pagein; 865 vm_page_t ma[VM_INITIAL_PAGEIN]; 866 vm_object_t object; 867 868 if (imgp->firstpage != NULL) 869 exec_unmap_first_page(imgp); 870 871 object = imgp->vp->v_object; 872 if (object == NULL) 873 return (EACCES); 874 VM_OBJECT_LOCK(object); 875 #if VM_NRESERVLEVEL > 0 876 if ((object->flags & OBJ_COLORED) == 0) { 877 object->flags |= OBJ_COLORED; 878 object->pg_color = 0; 879 } 880 #endif 881 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 882 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 883 initial_pagein = VM_INITIAL_PAGEIN; 884 if (initial_pagein > object->size) 885 initial_pagein = object->size; 886 for (i = 1; i < initial_pagein; i++) { 887 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 888 if (ma[i]->valid) 889 break; 890 if ((ma[i]->oflags & VPO_BUSY) || ma[i]->busy) 891 break; 892 vm_page_busy(ma[i]); 893 } else { 894 ma[i] = vm_page_alloc(object, i, 895 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 896 if (ma[i] == NULL) 897 break; 898 } 899 } 900 initial_pagein = i; 901 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 902 ma[0] = vm_page_lookup(object, 0); 903 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || 904 (ma[0]->valid == 0)) { 905 if (ma[0]) { 906 vm_page_lock_queues(); 907 vm_page_free(ma[0]); 908 vm_page_unlock_queues(); 909 } 910 VM_OBJECT_UNLOCK(object); 911 return (EIO); 912 } 913 } 914 vm_page_lock_queues(); 915 vm_page_hold(ma[0]); 916 vm_page_unlock_queues(); 917 vm_page_wakeup(ma[0]); 918 VM_OBJECT_UNLOCK(object); 919 920 imgp->firstpage = sf_buf_alloc(ma[0], 0); 921 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 922 923 return (0); 924 } 925 926 void 927 exec_unmap_first_page(imgp) 928 struct image_params *imgp; 929 { 930 vm_page_t m; 931 932 if (imgp->firstpage != NULL) { 933 m = sf_buf_page(imgp->firstpage); 934 sf_buf_free(imgp->firstpage); 935 imgp->firstpage = NULL; 936 vm_page_lock_queues(); 937 vm_page_unhold(m); 938 vm_page_unlock_queues(); 939 } 940 } 941 942 /* 943 * Destroy old address space, and allocate a new stack 944 * The new stack is only SGROWSIZ large because it is grown 945 * automatically in trap.c. 946 */ 947 int 948 exec_new_vmspace(imgp, sv) 949 struct image_params *imgp; 950 struct sysentvec *sv; 951 { 952 int error; 953 struct proc *p = imgp->proc; 954 struct vmspace *vmspace = p->p_vmspace; 955 vm_offset_t sv_minuser, stack_addr; 956 vm_map_t map; 957 u_long ssiz; 958 959 imgp->vmspace_destroyed = 1; 960 imgp->sysent = sv; 961 962 /* May be called with Giant held */ 963 EVENTHANDLER_INVOKE(process_exec, p, imgp); 964 965 /* 966 * Blow away entire process VM, if address space not shared, 967 * otherwise, create a new VM space so that other threads are 968 * not disrupted 969 */ 970 map = &vmspace->vm_map; 971 if (map_at_zero) 972 sv_minuser = sv->sv_minuser; 973 else 974 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 975 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 976 vm_map_max(map) == sv->sv_maxuser) { 977 shmexit(vmspace); 978 pmap_remove_pages(vmspace_pmap(vmspace)); 979 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 980 } else { 981 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 982 if (error) 983 return (error); 984 vmspace = p->p_vmspace; 985 map = &vmspace->vm_map; 986 } 987 988 /* Allocate a new stack */ 989 if (sv->sv_maxssiz != NULL) 990 ssiz = *sv->sv_maxssiz; 991 else 992 ssiz = maxssiz; 993 stack_addr = sv->sv_usrstack - ssiz; 994 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 995 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 996 if (error) 997 return (error); 998 999 #ifdef __ia64__ 1000 /* Allocate a new register stack */ 1001 stack_addr = IA64_BACKINGSTORE; 1002 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1003 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP); 1004 if (error) 1005 return (error); 1006 #endif 1007 1008 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 1009 * VM_STACK case, but they are still used to monitor the size of the 1010 * process stack so we can check the stack rlimit. 1011 */ 1012 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1013 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1014 1015 return (0); 1016 } 1017 1018 /* 1019 * Copy out argument and environment strings from the old process address 1020 * space into the temporary string buffer. 1021 */ 1022 int 1023 exec_copyin_args(struct image_args *args, char *fname, 1024 enum uio_seg segflg, char **argv, char **envv) 1025 { 1026 char *argp, *envp; 1027 int error; 1028 size_t length; 1029 1030 error = 0; 1031 1032 bzero(args, sizeof(*args)); 1033 if (argv == NULL) 1034 return (EFAULT); 1035 /* 1036 * Allocate temporary demand zeroed space for argument and 1037 * environment strings: 1038 * 1039 * o ARG_MAX for argument and environment; 1040 * o MAXSHELLCMDLEN for the name of interpreters. 1041 */ 1042 args->buf = (char *) kmem_alloc_wait(exec_map, 1043 PATH_MAX + ARG_MAX + MAXSHELLCMDLEN); 1044 if (args->buf == NULL) 1045 return (ENOMEM); 1046 args->begin_argv = args->buf; 1047 args->endp = args->begin_argv; 1048 args->stringspace = ARG_MAX; 1049 1050 args->fname = args->buf + ARG_MAX; 1051 1052 /* 1053 * Copy the file name. 1054 */ 1055 error = (segflg == UIO_SYSSPACE) ? 1056 copystr(fname, args->fname, PATH_MAX, &length) : 1057 copyinstr(fname, args->fname, PATH_MAX, &length); 1058 if (error != 0) 1059 goto err_exit; 1060 1061 /* 1062 * extract arguments first 1063 */ 1064 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 1065 if (argp == (caddr_t) -1) { 1066 error = EFAULT; 1067 goto err_exit; 1068 } 1069 if ((error = copyinstr(argp, args->endp, 1070 args->stringspace, &length))) { 1071 if (error == ENAMETOOLONG) 1072 error = E2BIG; 1073 goto err_exit; 1074 } 1075 args->stringspace -= length; 1076 args->endp += length; 1077 args->argc++; 1078 } 1079 1080 args->begin_envv = args->endp; 1081 1082 /* 1083 * extract environment strings 1084 */ 1085 if (envv) { 1086 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) { 1087 if (envp == (caddr_t)-1) { 1088 error = EFAULT; 1089 goto err_exit; 1090 } 1091 if ((error = copyinstr(envp, args->endp, 1092 args->stringspace, &length))) { 1093 if (error == ENAMETOOLONG) 1094 error = E2BIG; 1095 goto err_exit; 1096 } 1097 args->stringspace -= length; 1098 args->endp += length; 1099 args->envc++; 1100 } 1101 } 1102 1103 return (0); 1104 1105 err_exit: 1106 exec_free_args(args); 1107 return (error); 1108 } 1109 1110 static void 1111 exec_free_args(struct image_args *args) 1112 { 1113 1114 if (args->buf) { 1115 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf, 1116 PATH_MAX + ARG_MAX + MAXSHELLCMDLEN); 1117 args->buf = NULL; 1118 } 1119 } 1120 1121 /* 1122 * Copy strings out to the new process address space, constructing new arg 1123 * and env vector tables. Return a pointer to the base so that it can be used 1124 * as the initial stack pointer. 1125 */ 1126 register_t * 1127 exec_copyout_strings(imgp) 1128 struct image_params *imgp; 1129 { 1130 int argc, envc; 1131 char **vectp; 1132 char *stringp, *destp; 1133 register_t *stack_base; 1134 struct ps_strings *arginfo; 1135 struct proc *p; 1136 size_t execpath_len; 1137 int szsigcode; 1138 1139 /* 1140 * Calculate string base and vector table pointers. 1141 * Also deal with signal trampoline code for this exec type. 1142 */ 1143 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1144 execpath_len = strlen(imgp->execpath) + 1; 1145 else 1146 execpath_len = 0; 1147 p = imgp->proc; 1148 szsigcode = 0; 1149 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1150 if (p->p_sysent->sv_szsigcode != NULL) 1151 szsigcode = *(p->p_sysent->sv_szsigcode); 1152 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 1153 roundup(execpath_len, sizeof(char *)) - 1154 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *)); 1155 1156 /* 1157 * install sigcode 1158 */ 1159 if (szsigcode) 1160 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo - 1161 szsigcode), szsigcode); 1162 1163 /* 1164 * Copy the image path for the rtld. 1165 */ 1166 if (execpath_len != 0) { 1167 imgp->execpathp = (uintptr_t)arginfo - szsigcode - execpath_len; 1168 copyout(imgp->execpath, (void *)imgp->execpathp, 1169 execpath_len); 1170 } 1171 1172 /* 1173 * If we have a valid auxargs ptr, prepare some room 1174 * on the stack. 1175 */ 1176 if (imgp->auxargs) { 1177 /* 1178 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1179 * lower compatibility. 1180 */ 1181 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1182 (AT_COUNT * 2); 1183 /* 1184 * The '+ 2' is for the null pointers at the end of each of 1185 * the arg and env vector sets,and imgp->auxarg_size is room 1186 * for argument of Runtime loader. 1187 */ 1188 vectp = (char **)(destp - (imgp->args->argc + 1189 imgp->args->envc + 2 + imgp->auxarg_size + execpath_len) * 1190 sizeof(char *)); 1191 } else { 1192 /* 1193 * The '+ 2' is for the null pointers at the end of each of 1194 * the arg and env vector sets 1195 */ 1196 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) * 1197 sizeof(char *)); 1198 } 1199 1200 /* 1201 * vectp also becomes our initial stack base 1202 */ 1203 stack_base = (register_t *)vectp; 1204 1205 stringp = imgp->args->begin_argv; 1206 argc = imgp->args->argc; 1207 envc = imgp->args->envc; 1208 1209 /* 1210 * Copy out strings - arguments and environment. 1211 */ 1212 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace); 1213 1214 /* 1215 * Fill in "ps_strings" struct for ps, w, etc. 1216 */ 1217 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1218 suword(&arginfo->ps_nargvstr, argc); 1219 1220 /* 1221 * Fill in argument portion of vector table. 1222 */ 1223 for (; argc > 0; --argc) { 1224 suword(vectp++, (long)(intptr_t)destp); 1225 while (*stringp++ != 0) 1226 destp++; 1227 destp++; 1228 } 1229 1230 /* a null vector table pointer separates the argp's from the envp's */ 1231 suword(vectp++, 0); 1232 1233 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1234 suword(&arginfo->ps_nenvstr, envc); 1235 1236 /* 1237 * Fill in environment portion of vector table. 1238 */ 1239 for (; envc > 0; --envc) { 1240 suword(vectp++, (long)(intptr_t)destp); 1241 while (*stringp++ != 0) 1242 destp++; 1243 destp++; 1244 } 1245 1246 /* end of vector table is a null pointer */ 1247 suword(vectp, 0); 1248 1249 return (stack_base); 1250 } 1251 1252 /* 1253 * Check permissions of file to execute. 1254 * Called with imgp->vp locked. 1255 * Return 0 for success or error code on failure. 1256 */ 1257 int 1258 exec_check_permissions(imgp) 1259 struct image_params *imgp; 1260 { 1261 struct vnode *vp = imgp->vp; 1262 struct vattr *attr = imgp->attr; 1263 struct thread *td; 1264 int error; 1265 1266 td = curthread; /* XXXKSE */ 1267 1268 /* Get file attributes */ 1269 error = VOP_GETATTR(vp, attr, td->td_ucred, td); 1270 if (error) 1271 return (error); 1272 1273 #ifdef MAC 1274 error = mac_check_vnode_exec(td->td_ucred, imgp->vp, imgp); 1275 if (error) 1276 return (error); 1277 #endif 1278 1279 /* 1280 * 1) Check if file execution is disabled for the filesystem that this 1281 * file resides on. 1282 * 2) Insure that at least one execute bit is on - otherwise root 1283 * will always succeed, and we don't want to happen unless the 1284 * file really is executable. 1285 * 3) Insure that the file is a regular file. 1286 */ 1287 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1288 ((attr->va_mode & 0111) == 0) || 1289 (attr->va_type != VREG)) 1290 return (EACCES); 1291 1292 /* 1293 * Zero length files can't be exec'd 1294 */ 1295 if (attr->va_size == 0) 1296 return (ENOEXEC); 1297 1298 /* 1299 * Check for execute permission to file based on current credentials. 1300 */ 1301 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1302 if (error) 1303 return (error); 1304 1305 /* 1306 * Check number of open-for-writes on the file and deny execution 1307 * if there are any. 1308 */ 1309 if (vp->v_writecount) 1310 return (ETXTBSY); 1311 1312 /* 1313 * Call filesystem specific open routine (which does nothing in the 1314 * general case). 1315 */ 1316 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1317 if (error == 0) 1318 imgp->opened = 1; 1319 return (error); 1320 } 1321 1322 /* 1323 * Exec handler registration 1324 */ 1325 int 1326 exec_register(execsw_arg) 1327 const struct execsw *execsw_arg; 1328 { 1329 const struct execsw **es, **xs, **newexecsw; 1330 int count = 2; /* New slot and trailing NULL */ 1331 1332 if (execsw) 1333 for (es = execsw; *es; es++) 1334 count++; 1335 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1336 if (newexecsw == NULL) 1337 return (ENOMEM); 1338 xs = newexecsw; 1339 if (execsw) 1340 for (es = execsw; *es; es++) 1341 *xs++ = *es; 1342 *xs++ = execsw_arg; 1343 *xs = NULL; 1344 if (execsw) 1345 free(execsw, M_TEMP); 1346 execsw = newexecsw; 1347 return (0); 1348 } 1349 1350 int 1351 exec_unregister(execsw_arg) 1352 const struct execsw *execsw_arg; 1353 { 1354 const struct execsw **es, **xs, **newexecsw; 1355 int count = 1; 1356 1357 if (execsw == NULL) 1358 panic("unregister with no handlers left?\n"); 1359 1360 for (es = execsw; *es; es++) { 1361 if (*es == execsw_arg) 1362 break; 1363 } 1364 if (*es == NULL) 1365 return (ENOENT); 1366 for (es = execsw; *es; es++) 1367 if (*es != execsw_arg) 1368 count++; 1369 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1370 if (newexecsw == NULL) 1371 return (ENOMEM); 1372 xs = newexecsw; 1373 for (es = execsw; *es; es++) 1374 if (*es != execsw_arg) 1375 *xs++ = *es; 1376 *xs = NULL; 1377 if (execsw) 1378 free(execsw, M_TEMP); 1379 execsw = newexecsw; 1380 return (0); 1381 }
Cache object: 9007be43c3ca19249fceb2f2a4a53d08
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