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/7.1/sys/kern/kern_exec.c 197715 2009-10-02 18:09:56Z simon $"); 29 30 #include "opt_hwpmc_hooks.h" 31 #include "opt_kdtrace.h" 32 #include "opt_ktrace.h" 33 #include "opt_mac.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 #ifdef KTRACE 65 #include <sys/ktrace.h> 66 #endif 67 68 #include <vm/vm.h> 69 #include <vm/vm_param.h> 70 #include <vm/pmap.h> 71 #include <vm/vm_page.h> 72 #include <vm/vm_map.h> 73 #include <vm/vm_kern.h> 74 #include <vm/vm_extern.h> 75 #include <vm/vm_object.h> 76 #include <vm/vm_pager.h> 77 78 #ifdef HWPMC_HOOKS 79 #include <sys/pmckern.h> 80 #endif 81 82 #include <machine/reg.h> 83 84 #include <security/audit/audit.h> 85 #include <security/mac/mac_framework.h> 86 87 #ifdef KDTRACE_HOOKS 88 #include <sys/dtrace_bsd.h> 89 dtrace_execexit_func_t dtrace_fasttrap_exec; 90 #endif 91 92 SDT_PROVIDER_DECLARE(proc); 93 SDT_PROBE_DEFINE(proc, kernel, , exec); 94 SDT_PROBE_ARGTYPE(proc, kernel, , exec, 0, "char *"); 95 SDT_PROBE_DEFINE(proc, kernel, , exec_failure); 96 SDT_PROBE_ARGTYPE(proc, kernel, , exec_failure, 0, "int"); 97 SDT_PROBE_DEFINE(proc, kernel, , exec_success); 98 SDT_PROBE_ARGTYPE(proc, kernel, , exec_success, 0, "char *"); 99 100 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 101 102 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 103 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 104 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 105 static int do_execve(struct thread *td, struct image_args *args, 106 struct mac *mac_p); 107 static void exec_free_args(struct image_args *); 108 109 /* XXX This should be vm_size_t. */ 110 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD, 111 NULL, 0, sysctl_kern_ps_strings, "LU", ""); 112 113 /* XXX This should be vm_size_t. */ 114 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD, 115 NULL, 0, sysctl_kern_usrstack, "LU", ""); 116 117 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 118 NULL, 0, sysctl_kern_stackprot, "I", ""); 119 120 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 121 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 122 &ps_arg_cache_limit, 0, ""); 123 124 static int map_at_zero = 1; 125 TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero); 126 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &map_at_zero, 0, 127 "Permit processes to map an object at virtual address 0."); 128 129 static int 130 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 131 { 132 struct proc *p; 133 int error; 134 135 p = curproc; 136 #ifdef SCTL_MASK32 137 if (req->flags & SCTL_MASK32) { 138 unsigned int val; 139 val = (unsigned int)p->p_sysent->sv_psstrings; 140 error = SYSCTL_OUT(req, &val, sizeof(val)); 141 } else 142 #endif 143 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 144 sizeof(p->p_sysent->sv_psstrings)); 145 return error; 146 } 147 148 static int 149 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 150 { 151 struct proc *p; 152 int error; 153 154 p = curproc; 155 #ifdef SCTL_MASK32 156 if (req->flags & SCTL_MASK32) { 157 unsigned int val; 158 val = (unsigned int)p->p_sysent->sv_usrstack; 159 error = SYSCTL_OUT(req, &val, sizeof(val)); 160 } else 161 #endif 162 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 163 sizeof(p->p_sysent->sv_usrstack)); 164 return error; 165 } 166 167 static int 168 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 169 { 170 struct proc *p; 171 172 p = curproc; 173 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 174 sizeof(p->p_sysent->sv_stackprot))); 175 } 176 177 /* 178 * Each of the items is a pointer to a `const struct execsw', hence the 179 * double pointer here. 180 */ 181 static const struct execsw **execsw; 182 183 #ifndef _SYS_SYSPROTO_H_ 184 struct execve_args { 185 char *fname; 186 char **argv; 187 char **envv; 188 }; 189 #endif 190 191 int 192 execve(td, uap) 193 struct thread *td; 194 struct execve_args /* { 195 char *fname; 196 char **argv; 197 char **envv; 198 } */ *uap; 199 { 200 int error; 201 struct image_args args; 202 203 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 204 uap->argv, uap->envv); 205 if (error == 0) 206 error = kern_execve(td, &args, NULL); 207 return (error); 208 } 209 210 #ifndef _SYS_SYSPROTO_H_ 211 struct __mac_execve_args { 212 char *fname; 213 char **argv; 214 char **envv; 215 struct mac *mac_p; 216 }; 217 #endif 218 219 int 220 __mac_execve(td, uap) 221 struct thread *td; 222 struct __mac_execve_args /* { 223 char *fname; 224 char **argv; 225 char **envv; 226 struct mac *mac_p; 227 } */ *uap; 228 { 229 #ifdef MAC 230 int error; 231 struct image_args args; 232 233 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 234 uap->argv, uap->envv); 235 if (error == 0) 236 error = kern_execve(td, &args, uap->mac_p); 237 return (error); 238 #else 239 return (ENOSYS); 240 #endif 241 } 242 243 /* 244 * XXX: kern_execve has the astonishing property of not always returning to 245 * the caller. If sufficiently bad things happen during the call to 246 * do_execve(), it can end up calling exit1(); as a result, callers must 247 * avoid doing anything which they might need to undo (e.g., allocating 248 * memory). 249 */ 250 int 251 kern_execve(td, args, mac_p) 252 struct thread *td; 253 struct image_args *args; 254 struct mac *mac_p; 255 { 256 struct proc *p = td->td_proc; 257 int error; 258 259 AUDIT_ARG(argv, args->begin_argv, args->argc, 260 args->begin_envv - args->begin_argv); 261 AUDIT_ARG(envv, args->begin_envv, args->envc, 262 args->endp - args->begin_envv); 263 if (p->p_flag & P_HADTHREADS) { 264 PROC_LOCK(p); 265 if (thread_single(SINGLE_BOUNDARY)) { 266 PROC_UNLOCK(p); 267 exec_free_args(args); 268 return (ERESTART); /* Try again later. */ 269 } 270 PROC_UNLOCK(p); 271 } 272 273 error = do_execve(td, args, mac_p); 274 275 if (p->p_flag & P_HADTHREADS) { 276 PROC_LOCK(p); 277 /* 278 * If success, we upgrade to SINGLE_EXIT state to 279 * force other threads to suicide. 280 */ 281 if (error == 0) 282 thread_single(SINGLE_EXIT); 283 else 284 thread_single_end(); 285 PROC_UNLOCK(p); 286 } 287 288 return (error); 289 } 290 291 /* 292 * In-kernel implementation of execve(). All arguments are assumed to be 293 * userspace pointers from the passed thread. 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->opened = 0; 354 imgp->interpreter_name = args->buf + PATH_MAX + ARG_MAX; 355 imgp->auxargs = NULL; 356 imgp->vp = NULL; 357 imgp->object = NULL; 358 imgp->firstpage = NULL; 359 imgp->ps_strings = 0; 360 imgp->auxarg_size = 0; 361 imgp->args = args; 362 363 #ifdef MAC 364 error = mac_execve_enter(imgp, mac_p); 365 if (error) 366 goto exec_fail; 367 #endif 368 369 imgp->image_header = NULL; 370 371 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 372 373 /* 374 * Translate the file name. namei() returns a vnode pointer 375 * in ni_vp amoung other things. 376 * 377 * XXXAUDIT: It would be desirable to also audit the name of the 378 * interpreter if this is an interpreted binary. 379 */ 380 ndp = &nd; 381 NDINIT(ndp, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME | MPSAFE | 382 AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 383 384 interpret: 385 error = namei(ndp); 386 if (error) 387 goto exec_fail; 388 389 vfslocked = NDHASGIANT(ndp); 390 imgp->vp = ndp->ni_vp; 391 392 /* 393 * Check file permissions (also 'opens' file) 394 */ 395 error = exec_check_permissions(imgp); 396 if (error) 397 goto exec_fail_dealloc; 398 399 imgp->object = imgp->vp->v_object; 400 if (imgp->object != NULL) 401 vm_object_reference(imgp->object); 402 403 /* 404 * Set VV_TEXT now so no one can write to the executable while we're 405 * activating it. 406 * 407 * Remember if this was set before and unset it in case this is not 408 * actually an executable image. 409 */ 410 textset = imgp->vp->v_vflag & VV_TEXT; 411 imgp->vp->v_vflag |= VV_TEXT; 412 413 error = exec_map_first_page(imgp); 414 if (error) 415 goto exec_fail_dealloc; 416 417 imgp->proc->p_osrel = 0; 418 /* 419 * If the current process has a special image activator it 420 * wants to try first, call it. For example, emulating shell 421 * scripts differently. 422 */ 423 error = -1; 424 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 425 error = img_first(imgp); 426 427 /* 428 * Loop through the list of image activators, calling each one. 429 * An activator returns -1 if there is no match, 0 on success, 430 * and an error otherwise. 431 */ 432 for (i = 0; error == -1 && execsw[i]; ++i) { 433 if (execsw[i]->ex_imgact == NULL || 434 execsw[i]->ex_imgact == img_first) { 435 continue; 436 } 437 error = (*execsw[i]->ex_imgact)(imgp); 438 } 439 440 if (error) { 441 if (error == -1) { 442 if (textset == 0) 443 imgp->vp->v_vflag &= ~VV_TEXT; 444 error = ENOEXEC; 445 } 446 goto exec_fail_dealloc; 447 } 448 449 /* 450 * Special interpreter operation, cleanup and loop up to try to 451 * activate the interpreter. 452 */ 453 if (imgp->interpreted) { 454 exec_unmap_first_page(imgp); 455 /* 456 * VV_TEXT needs to be unset for scripts. There is a short 457 * period before we determine that something is a script where 458 * VV_TEXT will be set. The vnode lock is held over this 459 * entire period so nothing should illegitimately be blocked. 460 */ 461 imgp->vp->v_vflag &= ~VV_TEXT; 462 /* free name buffer and old vnode */ 463 NDFREE(ndp, NDF_ONLY_PNBUF); 464 #ifdef MAC 465 interplabel = mac_vnode_label_alloc(); 466 mac_copy_vnode_label(ndp->ni_vp->v_label, interplabel); 467 #endif 468 if (imgp->opened) { 469 VOP_CLOSE(ndp->ni_vp, FREAD, td->td_ucred, td); 470 imgp->opened = 0; 471 } 472 vput(ndp->ni_vp); 473 vm_object_deallocate(imgp->object); 474 imgp->object = NULL; 475 VFS_UNLOCK_GIANT(vfslocked); 476 vfslocked = 0; 477 /* set new name to that of the interpreter */ 478 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME | MPSAFE, 479 UIO_SYSSPACE, imgp->interpreter_name, td); 480 goto interpret; 481 } 482 483 /* 484 * NB: We unlock the vnode here because it is believed that none 485 * of the sv_copyout_strings/sv_fixup operations require the vnode. 486 */ 487 VOP_UNLOCK(imgp->vp, 0, td); 488 /* 489 * Copy out strings (args and env) and initialize stack base 490 */ 491 if (p->p_sysent->sv_copyout_strings) 492 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 493 else 494 stack_base = exec_copyout_strings(imgp); 495 496 /* 497 * If custom stack fixup routine present for this process 498 * let it do the stack setup. 499 * Else stuff argument count as first item on stack 500 */ 501 if (p->p_sysent->sv_fixup != NULL) 502 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 503 else 504 suword(--stack_base, imgp->args->argc); 505 506 /* 507 * For security and other reasons, the file descriptor table cannot 508 * be shared after an exec. 509 */ 510 fdunshare(p, td); 511 512 /* 513 * Malloc things before we need locks. 514 */ 515 newcred = crget(); 516 euip = uifind(attr.va_uid); 517 i = imgp->args->begin_envv - imgp->args->begin_argv; 518 /* Cache arguments if they fit inside our allowance */ 519 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 520 newargs = pargs_alloc(i); 521 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 522 } 523 524 /* close files on exec */ 525 fdcloseexec(td); 526 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY, td); 527 528 /* Get a reference to the vnode prior to locking the proc */ 529 VREF(ndp->ni_vp); 530 531 /* 532 * For security and other reasons, signal handlers cannot 533 * be shared after an exec. The new process gets a copy of the old 534 * handlers. In execsigs(), the new process will have its signals 535 * reset. 536 */ 537 PROC_LOCK(p); 538 if (sigacts_shared(p->p_sigacts)) { 539 oldsigacts = p->p_sigacts; 540 PROC_UNLOCK(p); 541 newsigacts = sigacts_alloc(); 542 sigacts_copy(newsigacts, oldsigacts); 543 PROC_LOCK(p); 544 p->p_sigacts = newsigacts; 545 } else 546 oldsigacts = NULL; 547 548 /* Stop profiling */ 549 stopprofclock(p); 550 551 /* reset caught signals */ 552 execsigs(p); 553 554 /* name this process - nameiexec(p, ndp) */ 555 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 556 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 557 p->p_comm[len] = 0; 558 559 /* 560 * mark as execed, wakeup the process that vforked (if any) and tell 561 * it that it now has its own resources back 562 */ 563 p->p_flag |= P_EXEC; 564 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 565 p->p_flag &= ~P_PPWAIT; 566 wakeup(p->p_pptr); 567 } 568 569 /* 570 * Implement image setuid/setgid. 571 * 572 * Don't honor setuid/setgid if the filesystem prohibits it or if 573 * the process is being traced. 574 * 575 * XXXMAC: For the time being, use NOSUID to also prohibit 576 * transitions on the file system. 577 */ 578 oldcred = p->p_ucred; 579 credential_changing = 0; 580 credential_changing |= (attr.va_mode & VSUID) && oldcred->cr_uid != 581 attr.va_uid; 582 credential_changing |= (attr.va_mode & VSGID) && oldcred->cr_gid != 583 attr.va_gid; 584 #ifdef MAC 585 will_transition = mac_execve_will_transition(oldcred, imgp->vp, 586 interplabel, imgp); 587 credential_changing |= will_transition; 588 #endif 589 590 if (credential_changing && 591 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 592 (p->p_flag & P_TRACED) == 0) { 593 /* 594 * Turn off syscall tracing for set-id programs, except for 595 * root. Record any set-id flags first to make sure that 596 * we do not regain any tracing during a possible block. 597 */ 598 setsugid(p); 599 600 #ifdef KTRACE 601 if (p->p_tracevp != NULL && 602 priv_check_cred(oldcred, PRIV_DEBUG_DIFFCRED, 0)) { 603 mtx_lock(&ktrace_mtx); 604 p->p_traceflag = 0; 605 tracevp = p->p_tracevp; 606 p->p_tracevp = NULL; 607 tracecred = p->p_tracecred; 608 p->p_tracecred = NULL; 609 mtx_unlock(&ktrace_mtx); 610 } 611 #endif 612 /* 613 * Close any file descriptors 0..2 that reference procfs, 614 * then make sure file descriptors 0..2 are in use. 615 * 616 * setugidsafety() may call closef() and then pfind() 617 * which may grab the process lock. 618 * fdcheckstd() may call falloc() which may block to 619 * allocate memory, so temporarily drop the process lock. 620 */ 621 PROC_UNLOCK(p); 622 setugidsafety(td); 623 VOP_UNLOCK(imgp->vp, 0, td); 624 error = fdcheckstd(td); 625 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY, td); 626 if (error != 0) 627 goto done1; 628 PROC_LOCK(p); 629 /* 630 * Set the new credentials. 631 */ 632 crcopy(newcred, oldcred); 633 if (attr.va_mode & VSUID) 634 change_euid(newcred, euip); 635 if (attr.va_mode & VSGID) 636 change_egid(newcred, attr.va_gid); 637 #ifdef MAC 638 if (will_transition) { 639 mac_execve_transition(oldcred, newcred, imgp->vp, 640 interplabel, imgp); 641 } 642 #endif 643 /* 644 * Implement correct POSIX saved-id behavior. 645 * 646 * XXXMAC: Note that the current logic will save the 647 * uid and gid if a MAC domain transition occurs, even 648 * though maybe it shouldn't. 649 */ 650 change_svuid(newcred, newcred->cr_uid); 651 change_svgid(newcred, newcred->cr_gid); 652 p->p_ucred = newcred; 653 newcred = NULL; 654 } else { 655 if (oldcred->cr_uid == oldcred->cr_ruid && 656 oldcred->cr_gid == oldcred->cr_rgid) 657 p->p_flag &= ~P_SUGID; 658 /* 659 * Implement correct POSIX saved-id behavior. 660 * 661 * XXX: It's not clear that the existing behavior is 662 * POSIX-compliant. A number of sources indicate that the 663 * saved uid/gid should only be updated if the new ruid is 664 * not equal to the old ruid, or the new euid is not equal 665 * to the old euid and the new euid is not equal to the old 666 * ruid. The FreeBSD code always updates the saved uid/gid. 667 * Also, this code uses the new (replaced) euid and egid as 668 * the source, which may or may not be the right ones to use. 669 */ 670 if (oldcred->cr_svuid != oldcred->cr_uid || 671 oldcred->cr_svgid != oldcred->cr_gid) { 672 crcopy(newcred, oldcred); 673 change_svuid(newcred, newcred->cr_uid); 674 change_svgid(newcred, newcred->cr_gid); 675 p->p_ucred = newcred; 676 newcred = NULL; 677 } 678 } 679 680 /* 681 * Store the vp for use in procfs. This vnode was referenced prior 682 * to locking the proc lock. 683 */ 684 textvp = p->p_textvp; 685 p->p_textvp = ndp->ni_vp; 686 687 #ifdef KDTRACE_HOOKS 688 /* 689 * Tell the DTrace fasttrap provider about the exec if it 690 * has declared an interest. 691 */ 692 if (dtrace_fasttrap_exec) 693 dtrace_fasttrap_exec(p); 694 #endif 695 696 /* 697 * Notify others that we exec'd, and clear the P_INEXEC flag 698 * as we're now a bona fide freshly-execed process. 699 */ 700 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 701 p->p_flag &= ~P_INEXEC; 702 703 /* 704 * If tracing the process, trap to debugger so breakpoints 705 * can be set before the program executes. 706 * Use tdsignal to deliver signal to current thread, use 707 * psignal may cause the signal to be delivered to wrong thread 708 * because that thread will exit, remember we are going to enter 709 * single thread mode. 710 */ 711 if (p->p_flag & P_TRACED) 712 tdsignal(p, td, SIGTRAP, NULL); 713 714 /* clear "fork but no exec" flag, as we _are_ execing */ 715 p->p_acflag &= ~AFORK; 716 717 /* 718 * Free any previous argument cache and replace it with 719 * the new argument cache, if any. 720 */ 721 oldargs = p->p_args; 722 p->p_args = newargs; 723 newargs = NULL; 724 725 #ifdef HWPMC_HOOKS 726 /* 727 * Check if system-wide sampling is in effect or if the 728 * current process is using PMCs. If so, do exec() time 729 * processing. This processing needs to happen AFTER the 730 * P_INEXEC flag is cleared. 731 * 732 * The proc lock needs to be released before taking the PMC 733 * SX. 734 */ 735 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 736 PROC_UNLOCK(p); 737 pe.pm_credentialschanged = credential_changing; 738 pe.pm_entryaddr = imgp->entry_addr; 739 740 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 741 } else 742 PROC_UNLOCK(p); 743 #else /* !HWPMC_HOOKS */ 744 PROC_UNLOCK(p); 745 #endif 746 747 /* Set values passed into the program in registers. */ 748 if (p->p_sysent->sv_setregs) 749 (*p->p_sysent->sv_setregs)(td, imgp->entry_addr, 750 (u_long)(uintptr_t)stack_base, imgp->ps_strings); 751 else 752 exec_setregs(td, imgp->entry_addr, 753 (u_long)(uintptr_t)stack_base, imgp->ps_strings); 754 755 vfs_mark_atime(imgp->vp, td); 756 757 done1: 758 /* 759 * Free any resources malloc'd earlier that we didn't use. 760 */ 761 uifree(euip); 762 if (newcred == NULL) 763 crfree(oldcred); 764 else 765 crfree(newcred); 766 VOP_UNLOCK(imgp->vp, 0, td); 767 768 SDT_PROBE(proc, kernel, , exec_success, args->fname, 0, 0, 0, 0); 769 770 /* 771 * Handle deferred decrement of ref counts. 772 */ 773 if (textvp != NULL) { 774 int tvfslocked; 775 776 tvfslocked = VFS_LOCK_GIANT(textvp->v_mount); 777 vrele(textvp); 778 VFS_UNLOCK_GIANT(tvfslocked); 779 } 780 if (ndp->ni_vp && error != 0) 781 vrele(ndp->ni_vp); 782 #ifdef KTRACE 783 if (tracevp != NULL) { 784 int tvfslocked; 785 786 tvfslocked = VFS_LOCK_GIANT(tracevp->v_mount); 787 vrele(tracevp); 788 VFS_UNLOCK_GIANT(tvfslocked); 789 } 790 if (tracecred != NULL) 791 crfree(tracecred); 792 #endif 793 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY, td); 794 pargs_drop(oldargs); 795 pargs_drop(newargs); 796 if (oldsigacts != NULL) 797 sigacts_free(oldsigacts); 798 799 exec_fail_dealloc: 800 801 /* 802 * free various allocated resources 803 */ 804 if (imgp->firstpage != NULL) 805 exec_unmap_first_page(imgp); 806 807 if (imgp->vp != NULL) { 808 NDFREE(ndp, NDF_ONLY_PNBUF); 809 if (imgp->opened) 810 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 811 vput(imgp->vp); 812 } 813 814 if (imgp->object != NULL) 815 vm_object_deallocate(imgp->object); 816 817 if (error == 0) { 818 /* 819 * Stop the process here if its stop event mask has 820 * the S_EXEC bit set. 821 */ 822 STOPEVENT(p, S_EXEC, 0); 823 goto done2; 824 } 825 826 exec_fail: 827 /* we're done here, clear P_INEXEC */ 828 PROC_LOCK(p); 829 p->p_flag &= ~P_INEXEC; 830 PROC_UNLOCK(p); 831 832 SDT_PROBE(proc, kernel, , exec_failure, error, 0, 0, 0, 0); 833 834 done2: 835 #ifdef MAC 836 mac_execve_exit(imgp); 837 if (interplabel != NULL) 838 mac_vnode_label_free(interplabel); 839 #endif 840 VFS_UNLOCK_GIANT(vfslocked); 841 exec_free_args(args); 842 843 if (error && imgp->vmspace_destroyed) { 844 /* sorry, no more process anymore. exit gracefully */ 845 exit1(td, W_EXITCODE(0, SIGABRT)); 846 /* NOT REACHED */ 847 } 848 return (error); 849 } 850 851 int 852 exec_map_first_page(imgp) 853 struct image_params *imgp; 854 { 855 int rv, i; 856 int initial_pagein; 857 vm_page_t ma[VM_INITIAL_PAGEIN]; 858 vm_object_t object; 859 860 if (imgp->firstpage != NULL) 861 exec_unmap_first_page(imgp); 862 863 object = imgp->vp->v_object; 864 if (object == NULL) 865 return (EACCES); 866 VM_OBJECT_LOCK(object); 867 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 868 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 869 initial_pagein = VM_INITIAL_PAGEIN; 870 if (initial_pagein > object->size) 871 initial_pagein = object->size; 872 for (i = 1; i < initial_pagein; i++) { 873 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 874 if (ma[i]->valid) 875 break; 876 if ((ma[i]->oflags & VPO_BUSY) || ma[i]->busy) 877 break; 878 vm_page_busy(ma[i]); 879 } else { 880 ma[i] = vm_page_alloc(object, i, 881 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 882 if (ma[i] == NULL) 883 break; 884 } 885 } 886 initial_pagein = i; 887 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 888 ma[0] = vm_page_lookup(object, 0); 889 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || 890 (ma[0]->valid == 0)) { 891 if (ma[0]) { 892 vm_page_lock_queues(); 893 vm_page_free(ma[0]); 894 vm_page_unlock_queues(); 895 } 896 VM_OBJECT_UNLOCK(object); 897 return (EIO); 898 } 899 } 900 vm_page_lock_queues(); 901 vm_page_hold(ma[0]); 902 vm_page_unlock_queues(); 903 vm_page_wakeup(ma[0]); 904 VM_OBJECT_UNLOCK(object); 905 906 imgp->firstpage = sf_buf_alloc(ma[0], 0); 907 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 908 909 return (0); 910 } 911 912 void 913 exec_unmap_first_page(imgp) 914 struct image_params *imgp; 915 { 916 vm_page_t m; 917 918 if (imgp->firstpage != NULL) { 919 m = sf_buf_page(imgp->firstpage); 920 sf_buf_free(imgp->firstpage); 921 imgp->firstpage = NULL; 922 vm_page_lock_queues(); 923 vm_page_unhold(m); 924 vm_page_unlock_queues(); 925 } 926 } 927 928 /* 929 * Destroy old address space, and allocate a new stack 930 * The new stack is only SGROWSIZ large because it is grown 931 * automatically in trap.c. 932 */ 933 int 934 exec_new_vmspace(imgp, sv) 935 struct image_params *imgp; 936 struct sysentvec *sv; 937 { 938 int error; 939 struct proc *p = imgp->proc; 940 struct vmspace *vmspace = p->p_vmspace; 941 vm_offset_t sv_minuser, stack_addr; 942 vm_map_t map; 943 u_long ssiz; 944 945 imgp->vmspace_destroyed = 1; 946 imgp->sysent = sv; 947 948 /* May be called with Giant held */ 949 EVENTHANDLER_INVOKE(process_exec, p, imgp); 950 951 /* 952 * Blow away entire process VM, if address space not shared, 953 * otherwise, create a new VM space so that other threads are 954 * not disrupted 955 */ 956 map = &vmspace->vm_map; 957 if (map_at_zero) 958 sv_minuser = sv->sv_minuser; 959 else 960 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 961 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 962 vm_map_max(map) == sv->sv_maxuser) { 963 shmexit(vmspace); 964 pmap_remove_pages(vmspace_pmap(vmspace)); 965 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 966 } else { 967 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 968 if (error) 969 return (error); 970 vmspace = p->p_vmspace; 971 map = &vmspace->vm_map; 972 } 973 974 /* Allocate a new stack */ 975 if (sv->sv_maxssiz != NULL) 976 ssiz = *sv->sv_maxssiz; 977 else 978 ssiz = maxssiz; 979 stack_addr = sv->sv_usrstack - ssiz; 980 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 981 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 982 if (error) 983 return (error); 984 985 #ifdef __ia64__ 986 /* Allocate a new register stack */ 987 stack_addr = IA64_BACKINGSTORE; 988 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 989 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP); 990 if (error) 991 return (error); 992 #endif 993 994 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 995 * VM_STACK case, but they are still used to monitor the size of the 996 * process stack so we can check the stack rlimit. 997 */ 998 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 999 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1000 1001 return (0); 1002 } 1003 1004 /* 1005 * Copy out argument and environment strings from the old process address 1006 * space into the temporary string buffer. 1007 */ 1008 int 1009 exec_copyin_args(struct image_args *args, char *fname, 1010 enum uio_seg segflg, char **argv, char **envv) 1011 { 1012 char *argp, *envp; 1013 int error; 1014 size_t length; 1015 1016 error = 0; 1017 1018 bzero(args, sizeof(*args)); 1019 if (argv == NULL) 1020 return (EFAULT); 1021 /* 1022 * Allocate temporary demand zeroed space for argument and 1023 * environment strings: 1024 * 1025 * o ARG_MAX for argument and environment; 1026 * o MAXSHELLCMDLEN for the name of interpreters. 1027 */ 1028 args->buf = (char *) kmem_alloc_wait(exec_map, 1029 PATH_MAX + ARG_MAX + MAXSHELLCMDLEN); 1030 if (args->buf == NULL) 1031 return (ENOMEM); 1032 args->begin_argv = args->buf; 1033 args->endp = args->begin_argv; 1034 args->stringspace = ARG_MAX; 1035 1036 args->fname = args->buf + ARG_MAX; 1037 1038 /* 1039 * Copy the file name. 1040 */ 1041 error = (segflg == UIO_SYSSPACE) ? 1042 copystr(fname, args->fname, PATH_MAX, &length) : 1043 copyinstr(fname, args->fname, PATH_MAX, &length); 1044 if (error != 0) 1045 goto err_exit; 1046 1047 /* 1048 * extract arguments first 1049 */ 1050 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 1051 if (argp == (caddr_t) -1) { 1052 error = EFAULT; 1053 goto err_exit; 1054 } 1055 if ((error = copyinstr(argp, args->endp, 1056 args->stringspace, &length))) { 1057 if (error == ENAMETOOLONG) 1058 error = E2BIG; 1059 goto err_exit; 1060 } 1061 args->stringspace -= length; 1062 args->endp += length; 1063 args->argc++; 1064 } 1065 1066 args->begin_envv = args->endp; 1067 1068 /* 1069 * extract environment strings 1070 */ 1071 if (envv) { 1072 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) { 1073 if (envp == (caddr_t)-1) { 1074 error = EFAULT; 1075 goto err_exit; 1076 } 1077 if ((error = copyinstr(envp, args->endp, 1078 args->stringspace, &length))) { 1079 if (error == ENAMETOOLONG) 1080 error = E2BIG; 1081 goto err_exit; 1082 } 1083 args->stringspace -= length; 1084 args->endp += length; 1085 args->envc++; 1086 } 1087 } 1088 1089 return (0); 1090 1091 err_exit: 1092 exec_free_args(args); 1093 return (error); 1094 } 1095 1096 static void 1097 exec_free_args(struct image_args *args) 1098 { 1099 1100 if (args->buf) { 1101 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf, 1102 PATH_MAX + ARG_MAX + MAXSHELLCMDLEN); 1103 args->buf = NULL; 1104 } 1105 } 1106 1107 /* 1108 * Copy strings out to the new process address space, constructing new arg 1109 * and env vector tables. Return a pointer to the base so that it can be used 1110 * as the initial stack pointer. 1111 */ 1112 register_t * 1113 exec_copyout_strings(imgp) 1114 struct image_params *imgp; 1115 { 1116 int argc, envc; 1117 char **vectp; 1118 char *stringp, *destp; 1119 register_t *stack_base; 1120 struct ps_strings *arginfo; 1121 struct proc *p; 1122 int szsigcode; 1123 1124 /* 1125 * Calculate string base and vector table pointers. 1126 * Also deal with signal trampoline code for this exec type. 1127 */ 1128 p = imgp->proc; 1129 szsigcode = 0; 1130 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1131 if (p->p_sysent->sv_szsigcode != NULL) 1132 szsigcode = *(p->p_sysent->sv_szsigcode); 1133 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 1134 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *)); 1135 1136 /* 1137 * install sigcode 1138 */ 1139 if (szsigcode) 1140 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo - 1141 szsigcode), szsigcode); 1142 1143 /* 1144 * If we have a valid auxargs ptr, prepare some room 1145 * on the stack. 1146 */ 1147 if (imgp->auxargs) { 1148 /* 1149 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1150 * lower compatibility. 1151 */ 1152 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1153 (AT_COUNT * 2); 1154 /* 1155 * The '+ 2' is for the null pointers at the end of each of 1156 * the arg and env vector sets,and imgp->auxarg_size is room 1157 * for argument of Runtime loader. 1158 */ 1159 vectp = (char **)(destp - (imgp->args->argc + 1160 imgp->args->envc + 2 + imgp->auxarg_size) * 1161 sizeof(char *)); 1162 1163 } else { 1164 /* 1165 * The '+ 2' is for the null pointers at the end of each of 1166 * the arg and env vector sets 1167 */ 1168 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) * 1169 sizeof(char *)); 1170 } 1171 1172 /* 1173 * vectp also becomes our initial stack base 1174 */ 1175 stack_base = (register_t *)vectp; 1176 1177 stringp = imgp->args->begin_argv; 1178 argc = imgp->args->argc; 1179 envc = imgp->args->envc; 1180 1181 /* 1182 * Copy out strings - arguments and environment. 1183 */ 1184 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace); 1185 1186 /* 1187 * Fill in "ps_strings" struct for ps, w, etc. 1188 */ 1189 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1190 suword(&arginfo->ps_nargvstr, argc); 1191 1192 /* 1193 * Fill in argument portion of vector table. 1194 */ 1195 for (; argc > 0; --argc) { 1196 suword(vectp++, (long)(intptr_t)destp); 1197 while (*stringp++ != 0) 1198 destp++; 1199 destp++; 1200 } 1201 1202 /* a null vector table pointer separates the argp's from the envp's */ 1203 suword(vectp++, 0); 1204 1205 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1206 suword(&arginfo->ps_nenvstr, envc); 1207 1208 /* 1209 * Fill in environment portion of vector table. 1210 */ 1211 for (; envc > 0; --envc) { 1212 suword(vectp++, (long)(intptr_t)destp); 1213 while (*stringp++ != 0) 1214 destp++; 1215 destp++; 1216 } 1217 1218 /* end of vector table is a null pointer */ 1219 suword(vectp, 0); 1220 1221 return (stack_base); 1222 } 1223 1224 /* 1225 * Check permissions of file to execute. 1226 * Called with imgp->vp locked. 1227 * Return 0 for success or error code on failure. 1228 */ 1229 int 1230 exec_check_permissions(imgp) 1231 struct image_params *imgp; 1232 { 1233 struct vnode *vp = imgp->vp; 1234 struct vattr *attr = imgp->attr; 1235 struct thread *td; 1236 int error; 1237 1238 td = curthread; /* XXXKSE */ 1239 1240 /* Get file attributes */ 1241 error = VOP_GETATTR(vp, attr, td->td_ucred, td); 1242 if (error) 1243 return (error); 1244 1245 #ifdef MAC 1246 error = mac_check_vnode_exec(td->td_ucred, imgp->vp, imgp); 1247 if (error) 1248 return (error); 1249 #endif 1250 1251 /* 1252 * 1) Check if file execution is disabled for the filesystem that this 1253 * file resides on. 1254 * 2) Insure that at least one execute bit is on - otherwise root 1255 * will always succeed, and we don't want to happen unless the 1256 * file really is executable. 1257 * 3) Insure that the file is a regular file. 1258 */ 1259 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1260 ((attr->va_mode & 0111) == 0) || 1261 (attr->va_type != VREG)) 1262 return (EACCES); 1263 1264 /* 1265 * Zero length files can't be exec'd 1266 */ 1267 if (attr->va_size == 0) 1268 return (ENOEXEC); 1269 1270 /* 1271 * Check for execute permission to file based on current credentials. 1272 */ 1273 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1274 if (error) 1275 return (error); 1276 1277 /* 1278 * Check number of open-for-writes on the file and deny execution 1279 * if there are any. 1280 */ 1281 if (vp->v_writecount) 1282 return (ETXTBSY); 1283 1284 /* 1285 * Call filesystem specific open routine (which does nothing in the 1286 * general case). 1287 */ 1288 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1289 if (error == 0) 1290 imgp->opened = 1; 1291 return (error); 1292 } 1293 1294 /* 1295 * Exec handler registration 1296 */ 1297 int 1298 exec_register(execsw_arg) 1299 const struct execsw *execsw_arg; 1300 { 1301 const struct execsw **es, **xs, **newexecsw; 1302 int count = 2; /* New slot and trailing NULL */ 1303 1304 if (execsw) 1305 for (es = execsw; *es; es++) 1306 count++; 1307 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1308 if (newexecsw == NULL) 1309 return (ENOMEM); 1310 xs = newexecsw; 1311 if (execsw) 1312 for (es = execsw; *es; es++) 1313 *xs++ = *es; 1314 *xs++ = execsw_arg; 1315 *xs = NULL; 1316 if (execsw) 1317 free(execsw, M_TEMP); 1318 execsw = newexecsw; 1319 return (0); 1320 } 1321 1322 int 1323 exec_unregister(execsw_arg) 1324 const struct execsw *execsw_arg; 1325 { 1326 const struct execsw **es, **xs, **newexecsw; 1327 int count = 1; 1328 1329 if (execsw == NULL) 1330 panic("unregister with no handlers left?\n"); 1331 1332 for (es = execsw; *es; es++) { 1333 if (*es == execsw_arg) 1334 break; 1335 } 1336 if (*es == NULL) 1337 return (ENOENT); 1338 for (es = execsw; *es; es++) 1339 if (*es != execsw_arg) 1340 count++; 1341 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1342 if (newexecsw == NULL) 1343 return (ENOMEM); 1344 xs = newexecsw; 1345 for (es = execsw; *es; es++) 1346 if (*es != execsw_arg) 1347 *xs++ = *es; 1348 *xs = NULL; 1349 if (execsw) 1350 free(execsw, M_TEMP); 1351 execsw = newexecsw; 1352 return (0); 1353 }
Cache object: d2c9da958e37c9cb693496ae9a70a4c2
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