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/7.2/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 #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; 363 364 #ifdef MAC 365 error = mac_execve_enter(imgp, mac_p); 366 if (error) 367 goto exec_fail; 368 #endif 369 370 imgp->image_header = NULL; 371 372 /* 373 * Translate the file name. namei() returns a vnode pointer 374 * in ni_vp amoung other things. 375 * 376 * XXXAUDIT: It would be desirable to also audit the name of the 377 * interpreter if this is an interpreted binary. 378 */ 379 ndp = &nd; 380 NDINIT(ndp, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME | MPSAFE | 381 AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 382 383 SDT_PROBE(proc, kernel, , exec, args->fname, 0, 0, 0, 0 ); 384 385 interpret: 386 error = namei(ndp); 387 if (error) 388 goto exec_fail; 389 390 vfslocked = NDHASGIANT(ndp); 391 imgp->vp = ndp->ni_vp; 392 393 /* 394 * Check file permissions (also 'opens' file) 395 */ 396 error = exec_check_permissions(imgp); 397 if (error) 398 goto exec_fail_dealloc; 399 400 imgp->object = imgp->vp->v_object; 401 if (imgp->object != NULL) 402 vm_object_reference(imgp->object); 403 404 /* 405 * Set VV_TEXT now so no one can write to the executable while we're 406 * activating it. 407 * 408 * Remember if this was set before and unset it in case this is not 409 * actually an executable image. 410 */ 411 textset = imgp->vp->v_vflag & VV_TEXT; 412 imgp->vp->v_vflag |= VV_TEXT; 413 414 error = exec_map_first_page(imgp); 415 if (error) 416 goto exec_fail_dealloc; 417 418 imgp->proc->p_osrel = 0; 419 /* 420 * If the current process has a special image activator it 421 * wants to try first, call it. For example, emulating shell 422 * scripts differently. 423 */ 424 error = -1; 425 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 426 error = img_first(imgp); 427 428 /* 429 * Loop through the list of image activators, calling each one. 430 * An activator returns -1 if there is no match, 0 on success, 431 * and an error otherwise. 432 */ 433 for (i = 0; error == -1 && execsw[i]; ++i) { 434 if (execsw[i]->ex_imgact == NULL || 435 execsw[i]->ex_imgact == img_first) { 436 continue; 437 } 438 error = (*execsw[i]->ex_imgact)(imgp); 439 } 440 441 if (error) { 442 if (error == -1) { 443 if (textset == 0) 444 imgp->vp->v_vflag &= ~VV_TEXT; 445 error = ENOEXEC; 446 } 447 goto exec_fail_dealloc; 448 } 449 450 /* 451 * Special interpreter operation, cleanup and loop up to try to 452 * activate the interpreter. 453 */ 454 if (imgp->interpreted) { 455 exec_unmap_first_page(imgp); 456 /* 457 * VV_TEXT needs to be unset for scripts. There is a short 458 * period before we determine that something is a script where 459 * VV_TEXT will be set. The vnode lock is held over this 460 * entire period so nothing should illegitimately be blocked. 461 */ 462 imgp->vp->v_vflag &= ~VV_TEXT; 463 /* free name buffer and old vnode */ 464 NDFREE(ndp, NDF_ONLY_PNBUF); 465 #ifdef MAC 466 interplabel = mac_vnode_label_alloc(); 467 mac_copy_vnode_label(ndp->ni_vp->v_label, interplabel); 468 #endif 469 if (imgp->opened) { 470 VOP_CLOSE(ndp->ni_vp, FREAD, td->td_ucred, td); 471 imgp->opened = 0; 472 } 473 vput(ndp->ni_vp); 474 vm_object_deallocate(imgp->object); 475 imgp->object = NULL; 476 VFS_UNLOCK_GIANT(vfslocked); 477 vfslocked = 0; 478 /* set new name to that of the interpreter */ 479 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME | MPSAFE, 480 UIO_SYSSPACE, imgp->interpreter_name, td); 481 goto interpret; 482 } 483 484 /* 485 * NB: We unlock the vnode here because it is believed that none 486 * of the sv_copyout_strings/sv_fixup operations require the vnode. 487 */ 488 VOP_UNLOCK(imgp->vp, 0, td); 489 /* 490 * Copy out strings (args and env) and initialize stack base 491 */ 492 if (p->p_sysent->sv_copyout_strings) 493 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 494 else 495 stack_base = exec_copyout_strings(imgp); 496 497 /* 498 * If custom stack fixup routine present for this process 499 * let it do the stack setup. 500 * Else stuff argument count as first item on stack 501 */ 502 if (p->p_sysent->sv_fixup != NULL) 503 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 504 else 505 suword(--stack_base, imgp->args->argc); 506 507 /* 508 * For security and other reasons, the file descriptor table cannot 509 * be shared after an exec. 510 */ 511 fdunshare(p, td); 512 513 /* 514 * Malloc things before we need locks. 515 */ 516 newcred = crget(); 517 euip = uifind(attr.va_uid); 518 i = imgp->args->begin_envv - imgp->args->begin_argv; 519 /* Cache arguments if they fit inside our allowance */ 520 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 521 newargs = pargs_alloc(i); 522 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 523 } 524 525 /* close files on exec */ 526 fdcloseexec(td); 527 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY, td); 528 529 /* Get a reference to the vnode prior to locking the proc */ 530 VREF(ndp->ni_vp); 531 532 /* 533 * For security and other reasons, signal handlers cannot 534 * be shared after an exec. The new process gets a copy of the old 535 * handlers. In execsigs(), the new process will have its signals 536 * reset. 537 */ 538 PROC_LOCK(p); 539 if (sigacts_shared(p->p_sigacts)) { 540 oldsigacts = p->p_sigacts; 541 PROC_UNLOCK(p); 542 newsigacts = sigacts_alloc(); 543 sigacts_copy(newsigacts, oldsigacts); 544 PROC_LOCK(p); 545 p->p_sigacts = newsigacts; 546 } else 547 oldsigacts = NULL; 548 549 /* Stop profiling */ 550 stopprofclock(p); 551 552 /* reset caught signals */ 553 execsigs(p); 554 555 /* name this process - nameiexec(p, ndp) */ 556 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 557 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 558 p->p_comm[len] = 0; 559 560 /* 561 * mark as execed, wakeup the process that vforked (if any) and tell 562 * it that it now has its own resources back 563 */ 564 p->p_flag |= P_EXEC; 565 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 566 p->p_flag &= ~P_PPWAIT; 567 wakeup(p->p_pptr); 568 } 569 570 /* 571 * Implement image setuid/setgid. 572 * 573 * Don't honor setuid/setgid if the filesystem prohibits it or if 574 * the process is being traced. 575 * 576 * XXXMAC: For the time being, use NOSUID to also prohibit 577 * transitions on the file system. 578 */ 579 oldcred = p->p_ucred; 580 credential_changing = 0; 581 credential_changing |= (attr.va_mode & VSUID) && oldcred->cr_uid != 582 attr.va_uid; 583 credential_changing |= (attr.va_mode & VSGID) && oldcred->cr_gid != 584 attr.va_gid; 585 #ifdef MAC 586 will_transition = mac_execve_will_transition(oldcred, imgp->vp, 587 interplabel, imgp); 588 credential_changing |= will_transition; 589 #endif 590 591 if (credential_changing && 592 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 593 (p->p_flag & P_TRACED) == 0) { 594 /* 595 * Turn off syscall tracing for set-id programs, except for 596 * root. Record any set-id flags first to make sure that 597 * we do not regain any tracing during a possible block. 598 */ 599 setsugid(p); 600 601 #ifdef KTRACE 602 if (p->p_tracevp != NULL && 603 priv_check_cred(oldcred, PRIV_DEBUG_DIFFCRED, 0)) { 604 mtx_lock(&ktrace_mtx); 605 p->p_traceflag = 0; 606 tracevp = p->p_tracevp; 607 p->p_tracevp = NULL; 608 tracecred = p->p_tracecred; 609 p->p_tracecred = NULL; 610 mtx_unlock(&ktrace_mtx); 611 } 612 #endif 613 /* 614 * Close any file descriptors 0..2 that reference procfs, 615 * then make sure file descriptors 0..2 are in use. 616 * 617 * setugidsafety() may call closef() and then pfind() 618 * which may grab the process lock. 619 * fdcheckstd() may call falloc() which may block to 620 * allocate memory, so temporarily drop the process lock. 621 */ 622 PROC_UNLOCK(p); 623 setugidsafety(td); 624 VOP_UNLOCK(imgp->vp, 0, td); 625 error = fdcheckstd(td); 626 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY, td); 627 if (error != 0) 628 goto done1; 629 PROC_LOCK(p); 630 /* 631 * Set the new credentials. 632 */ 633 crcopy(newcred, oldcred); 634 if (attr.va_mode & VSUID) 635 change_euid(newcred, euip); 636 if (attr.va_mode & VSGID) 637 change_egid(newcred, attr.va_gid); 638 #ifdef MAC 639 if (will_transition) { 640 mac_execve_transition(oldcred, newcred, imgp->vp, 641 interplabel, imgp); 642 } 643 #endif 644 /* 645 * Implement correct POSIX saved-id behavior. 646 * 647 * XXXMAC: Note that the current logic will save the 648 * uid and gid if a MAC domain transition occurs, even 649 * though maybe it shouldn't. 650 */ 651 change_svuid(newcred, newcred->cr_uid); 652 change_svgid(newcred, newcred->cr_gid); 653 p->p_ucred = newcred; 654 newcred = NULL; 655 } else { 656 if (oldcred->cr_uid == oldcred->cr_ruid && 657 oldcred->cr_gid == oldcred->cr_rgid) 658 p->p_flag &= ~P_SUGID; 659 /* 660 * Implement correct POSIX saved-id behavior. 661 * 662 * XXX: It's not clear that the existing behavior is 663 * POSIX-compliant. A number of sources indicate that the 664 * saved uid/gid should only be updated if the new ruid is 665 * not equal to the old ruid, or the new euid is not equal 666 * to the old euid and the new euid is not equal to the old 667 * ruid. The FreeBSD code always updates the saved uid/gid. 668 * Also, this code uses the new (replaced) euid and egid as 669 * the source, which may or may not be the right ones to use. 670 */ 671 if (oldcred->cr_svuid != oldcred->cr_uid || 672 oldcred->cr_svgid != oldcred->cr_gid) { 673 crcopy(newcred, oldcred); 674 change_svuid(newcred, newcred->cr_uid); 675 change_svgid(newcred, newcred->cr_gid); 676 p->p_ucred = newcred; 677 newcred = NULL; 678 } 679 } 680 681 /* 682 * Store the vp for use in procfs. This vnode was referenced prior 683 * to locking the proc lock. 684 */ 685 textvp = p->p_textvp; 686 p->p_textvp = ndp->ni_vp; 687 688 #ifdef KDTRACE_HOOKS 689 /* 690 * Tell the DTrace fasttrap provider about the exec if it 691 * has declared an interest. 692 */ 693 if (dtrace_fasttrap_exec) 694 dtrace_fasttrap_exec(p); 695 #endif 696 697 /* 698 * Notify others that we exec'd, and clear the P_INEXEC flag 699 * as we're now a bona fide freshly-execed process. 700 */ 701 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 702 p->p_flag &= ~P_INEXEC; 703 704 /* 705 * If tracing the process, trap to debugger so breakpoints 706 * can be set before the program executes. 707 * Use tdsignal to deliver signal to current thread, use 708 * psignal may cause the signal to be delivered to wrong thread 709 * because that thread will exit, remember we are going to enter 710 * single thread mode. 711 */ 712 if (p->p_flag & P_TRACED) 713 tdsignal(p, td, SIGTRAP, NULL); 714 715 /* clear "fork but no exec" flag, as we _are_ execing */ 716 p->p_acflag &= ~AFORK; 717 718 /* 719 * Free any previous argument cache and replace it with 720 * the new argument cache, if any. 721 */ 722 oldargs = p->p_args; 723 p->p_args = newargs; 724 newargs = NULL; 725 726 #ifdef HWPMC_HOOKS 727 /* 728 * Check if system-wide sampling is in effect or if the 729 * current process is using PMCs. If so, do exec() time 730 * processing. This processing needs to happen AFTER the 731 * P_INEXEC flag is cleared. 732 * 733 * The proc lock needs to be released before taking the PMC 734 * SX. 735 */ 736 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 737 PROC_UNLOCK(p); 738 pe.pm_credentialschanged = credential_changing; 739 pe.pm_entryaddr = imgp->entry_addr; 740 741 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 742 } else 743 PROC_UNLOCK(p); 744 #else /* !HWPMC_HOOKS */ 745 PROC_UNLOCK(p); 746 #endif 747 748 /* Set values passed into the program in registers. */ 749 if (p->p_sysent->sv_setregs) 750 (*p->p_sysent->sv_setregs)(td, imgp->entry_addr, 751 (u_long)(uintptr_t)stack_base, imgp->ps_strings); 752 else 753 exec_setregs(td, imgp->entry_addr, 754 (u_long)(uintptr_t)stack_base, imgp->ps_strings); 755 756 vfs_mark_atime(imgp->vp, td); 757 758 SDT_PROBE(proc, kernel, , exec_success, args->fname, 0, 0, 0, 0); 759 done1: 760 /* 761 * Free any resources malloc'd earlier that we didn't use. 762 */ 763 uifree(euip); 764 if (newcred == NULL) 765 crfree(oldcred); 766 else 767 crfree(newcred); 768 VOP_UNLOCK(imgp->vp, 0, td); 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 #if VM_NRESERVLEVEL > 0 868 if ((object->flags & OBJ_COLORED) == 0) { 869 object->flags |= OBJ_COLORED; 870 object->pg_color = 0; 871 } 872 #endif 873 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 874 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 875 initial_pagein = VM_INITIAL_PAGEIN; 876 if (initial_pagein > object->size) 877 initial_pagein = object->size; 878 for (i = 1; i < initial_pagein; i++) { 879 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 880 if (ma[i]->valid) 881 break; 882 if ((ma[i]->oflags & VPO_BUSY) || ma[i]->busy) 883 break; 884 vm_page_busy(ma[i]); 885 } else { 886 ma[i] = vm_page_alloc(object, i, 887 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 888 if (ma[i] == NULL) 889 break; 890 } 891 } 892 initial_pagein = i; 893 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 894 ma[0] = vm_page_lookup(object, 0); 895 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || 896 (ma[0]->valid == 0)) { 897 if (ma[0]) { 898 vm_page_lock_queues(); 899 vm_page_free(ma[0]); 900 vm_page_unlock_queues(); 901 } 902 VM_OBJECT_UNLOCK(object); 903 return (EIO); 904 } 905 } 906 vm_page_lock_queues(); 907 vm_page_hold(ma[0]); 908 vm_page_unlock_queues(); 909 vm_page_wakeup(ma[0]); 910 VM_OBJECT_UNLOCK(object); 911 912 imgp->firstpage = sf_buf_alloc(ma[0], 0); 913 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 914 915 return (0); 916 } 917 918 void 919 exec_unmap_first_page(imgp) 920 struct image_params *imgp; 921 { 922 vm_page_t m; 923 924 if (imgp->firstpage != NULL) { 925 m = sf_buf_page(imgp->firstpage); 926 sf_buf_free(imgp->firstpage); 927 imgp->firstpage = NULL; 928 vm_page_lock_queues(); 929 vm_page_unhold(m); 930 vm_page_unlock_queues(); 931 } 932 } 933 934 /* 935 * Destroy old address space, and allocate a new stack 936 * The new stack is only SGROWSIZ large because it is grown 937 * automatically in trap.c. 938 */ 939 int 940 exec_new_vmspace(imgp, sv) 941 struct image_params *imgp; 942 struct sysentvec *sv; 943 { 944 int error; 945 struct proc *p = imgp->proc; 946 struct vmspace *vmspace = p->p_vmspace; 947 vm_offset_t sv_minuser, stack_addr; 948 vm_map_t map; 949 u_long ssiz; 950 951 imgp->vmspace_destroyed = 1; 952 imgp->sysent = sv; 953 954 /* May be called with Giant held */ 955 EVENTHANDLER_INVOKE(process_exec, p, imgp); 956 957 /* 958 * Blow away entire process VM, if address space not shared, 959 * otherwise, create a new VM space so that other threads are 960 * not disrupted 961 */ 962 map = &vmspace->vm_map; 963 if (map_at_zero) 964 sv_minuser = sv->sv_minuser; 965 else 966 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 967 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 968 vm_map_max(map) == sv->sv_maxuser) { 969 shmexit(vmspace); 970 pmap_remove_pages(vmspace_pmap(vmspace)); 971 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 972 } else { 973 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 974 if (error) 975 return (error); 976 vmspace = p->p_vmspace; 977 map = &vmspace->vm_map; 978 } 979 980 /* Allocate a new stack */ 981 if (sv->sv_maxssiz != NULL) 982 ssiz = *sv->sv_maxssiz; 983 else 984 ssiz = maxssiz; 985 stack_addr = sv->sv_usrstack - ssiz; 986 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 987 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 988 if (error) 989 return (error); 990 991 #ifdef __ia64__ 992 /* Allocate a new register stack */ 993 stack_addr = IA64_BACKINGSTORE; 994 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 995 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP); 996 if (error) 997 return (error); 998 #endif 999 1000 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 1001 * VM_STACK case, but they are still used to monitor the size of the 1002 * process stack so we can check the stack rlimit. 1003 */ 1004 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1005 vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - ssiz; 1006 1007 return (0); 1008 } 1009 1010 /* 1011 * Copy out argument and environment strings from the old process address 1012 * space into the temporary string buffer. 1013 */ 1014 int 1015 exec_copyin_args(struct image_args *args, char *fname, 1016 enum uio_seg segflg, char **argv, char **envv) 1017 { 1018 char *argp, *envp; 1019 int error; 1020 size_t length; 1021 1022 error = 0; 1023 1024 bzero(args, sizeof(*args)); 1025 if (argv == NULL) 1026 return (EFAULT); 1027 /* 1028 * Allocate temporary demand zeroed space for argument and 1029 * environment strings: 1030 * 1031 * o ARG_MAX for argument and environment; 1032 * o MAXSHELLCMDLEN for the name of interpreters. 1033 */ 1034 args->buf = (char *) kmem_alloc_wait(exec_map, 1035 PATH_MAX + ARG_MAX + MAXSHELLCMDLEN); 1036 if (args->buf == NULL) 1037 return (ENOMEM); 1038 args->begin_argv = args->buf; 1039 args->endp = args->begin_argv; 1040 args->stringspace = ARG_MAX; 1041 1042 args->fname = args->buf + ARG_MAX; 1043 1044 /* 1045 * Copy the file name. 1046 */ 1047 error = (segflg == UIO_SYSSPACE) ? 1048 copystr(fname, args->fname, PATH_MAX, &length) : 1049 copyinstr(fname, args->fname, PATH_MAX, &length); 1050 if (error != 0) 1051 goto err_exit; 1052 1053 /* 1054 * extract arguments first 1055 */ 1056 while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { 1057 if (argp == (caddr_t) -1) { 1058 error = EFAULT; 1059 goto err_exit; 1060 } 1061 if ((error = copyinstr(argp, args->endp, 1062 args->stringspace, &length))) { 1063 if (error == ENAMETOOLONG) 1064 error = E2BIG; 1065 goto err_exit; 1066 } 1067 args->stringspace -= length; 1068 args->endp += length; 1069 args->argc++; 1070 } 1071 1072 args->begin_envv = args->endp; 1073 1074 /* 1075 * extract environment strings 1076 */ 1077 if (envv) { 1078 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) { 1079 if (envp == (caddr_t)-1) { 1080 error = EFAULT; 1081 goto err_exit; 1082 } 1083 if ((error = copyinstr(envp, args->endp, 1084 args->stringspace, &length))) { 1085 if (error == ENAMETOOLONG) 1086 error = E2BIG; 1087 goto err_exit; 1088 } 1089 args->stringspace -= length; 1090 args->endp += length; 1091 args->envc++; 1092 } 1093 } 1094 1095 return (0); 1096 1097 err_exit: 1098 exec_free_args(args); 1099 return (error); 1100 } 1101 1102 static void 1103 exec_free_args(struct image_args *args) 1104 { 1105 1106 if (args->buf) { 1107 kmem_free_wakeup(exec_map, (vm_offset_t)args->buf, 1108 PATH_MAX + ARG_MAX + MAXSHELLCMDLEN); 1109 args->buf = NULL; 1110 } 1111 } 1112 1113 /* 1114 * Copy strings out to the new process address space, constructing new arg 1115 * and env vector tables. Return a pointer to the base so that it can be used 1116 * as the initial stack pointer. 1117 */ 1118 register_t * 1119 exec_copyout_strings(imgp) 1120 struct image_params *imgp; 1121 { 1122 int argc, envc; 1123 char **vectp; 1124 char *stringp, *destp; 1125 register_t *stack_base; 1126 struct ps_strings *arginfo; 1127 struct proc *p; 1128 int szsigcode; 1129 1130 /* 1131 * Calculate string base and vector table pointers. 1132 * Also deal with signal trampoline code for this exec type. 1133 */ 1134 p = imgp->proc; 1135 szsigcode = 0; 1136 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1137 if (p->p_sysent->sv_szsigcode != NULL) 1138 szsigcode = *(p->p_sysent->sv_szsigcode); 1139 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 1140 roundup((ARG_MAX - imgp->args->stringspace), sizeof(char *)); 1141 1142 /* 1143 * install sigcode 1144 */ 1145 if (szsigcode) 1146 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo - 1147 szsigcode), szsigcode); 1148 1149 /* 1150 * If we have a valid auxargs ptr, prepare some room 1151 * on the stack. 1152 */ 1153 if (imgp->auxargs) { 1154 /* 1155 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1156 * lower compatibility. 1157 */ 1158 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1159 (AT_COUNT * 2); 1160 /* 1161 * The '+ 2' is for the null pointers at the end of each of 1162 * the arg and env vector sets,and imgp->auxarg_size is room 1163 * for argument of Runtime loader. 1164 */ 1165 vectp = (char **)(destp - (imgp->args->argc + 1166 imgp->args->envc + 2 + imgp->auxarg_size) * 1167 sizeof(char *)); 1168 1169 } else { 1170 /* 1171 * The '+ 2' is for the null pointers at the end of each of 1172 * the arg and env vector sets 1173 */ 1174 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) * 1175 sizeof(char *)); 1176 } 1177 1178 /* 1179 * vectp also becomes our initial stack base 1180 */ 1181 stack_base = (register_t *)vectp; 1182 1183 stringp = imgp->args->begin_argv; 1184 argc = imgp->args->argc; 1185 envc = imgp->args->envc; 1186 1187 /* 1188 * Copy out strings - arguments and environment. 1189 */ 1190 copyout(stringp, destp, ARG_MAX - imgp->args->stringspace); 1191 1192 /* 1193 * Fill in "ps_strings" struct for ps, w, etc. 1194 */ 1195 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1196 suword(&arginfo->ps_nargvstr, argc); 1197 1198 /* 1199 * Fill in argument portion of vector table. 1200 */ 1201 for (; argc > 0; --argc) { 1202 suword(vectp++, (long)(intptr_t)destp); 1203 while (*stringp++ != 0) 1204 destp++; 1205 destp++; 1206 } 1207 1208 /* a null vector table pointer separates the argp's from the envp's */ 1209 suword(vectp++, 0); 1210 1211 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1212 suword(&arginfo->ps_nenvstr, envc); 1213 1214 /* 1215 * Fill in environment portion of vector table. 1216 */ 1217 for (; envc > 0; --envc) { 1218 suword(vectp++, (long)(intptr_t)destp); 1219 while (*stringp++ != 0) 1220 destp++; 1221 destp++; 1222 } 1223 1224 /* end of vector table is a null pointer */ 1225 suword(vectp, 0); 1226 1227 return (stack_base); 1228 } 1229 1230 /* 1231 * Check permissions of file to execute. 1232 * Called with imgp->vp locked. 1233 * Return 0 for success or error code on failure. 1234 */ 1235 int 1236 exec_check_permissions(imgp) 1237 struct image_params *imgp; 1238 { 1239 struct vnode *vp = imgp->vp; 1240 struct vattr *attr = imgp->attr; 1241 struct thread *td; 1242 int error; 1243 1244 td = curthread; /* XXXKSE */ 1245 1246 /* Get file attributes */ 1247 error = VOP_GETATTR(vp, attr, td->td_ucred, td); 1248 if (error) 1249 return (error); 1250 1251 #ifdef MAC 1252 error = mac_check_vnode_exec(td->td_ucred, imgp->vp, imgp); 1253 if (error) 1254 return (error); 1255 #endif 1256 1257 /* 1258 * 1) Check if file execution is disabled for the filesystem that this 1259 * file resides on. 1260 * 2) Insure that at least one execute bit is on - otherwise root 1261 * will always succeed, and we don't want to happen unless the 1262 * file really is executable. 1263 * 3) Insure that the file is a regular file. 1264 */ 1265 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1266 ((attr->va_mode & 0111) == 0) || 1267 (attr->va_type != VREG)) 1268 return (EACCES); 1269 1270 /* 1271 * Zero length files can't be exec'd 1272 */ 1273 if (attr->va_size == 0) 1274 return (ENOEXEC); 1275 1276 /* 1277 * Check for execute permission to file based on current credentials. 1278 */ 1279 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1280 if (error) 1281 return (error); 1282 1283 /* 1284 * Check number of open-for-writes on the file and deny execution 1285 * if there are any. 1286 */ 1287 if (vp->v_writecount) 1288 return (ETXTBSY); 1289 1290 /* 1291 * Call filesystem specific open routine (which does nothing in the 1292 * general case). 1293 */ 1294 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1295 if (error == 0) 1296 imgp->opened = 1; 1297 return (error); 1298 } 1299 1300 /* 1301 * Exec handler registration 1302 */ 1303 int 1304 exec_register(execsw_arg) 1305 const struct execsw *execsw_arg; 1306 { 1307 const struct execsw **es, **xs, **newexecsw; 1308 int count = 2; /* New slot and trailing NULL */ 1309 1310 if (execsw) 1311 for (es = execsw; *es; es++) 1312 count++; 1313 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1314 if (newexecsw == NULL) 1315 return (ENOMEM); 1316 xs = newexecsw; 1317 if (execsw) 1318 for (es = execsw; *es; es++) 1319 *xs++ = *es; 1320 *xs++ = execsw_arg; 1321 *xs = NULL; 1322 if (execsw) 1323 free(execsw, M_TEMP); 1324 execsw = newexecsw; 1325 return (0); 1326 } 1327 1328 int 1329 exec_unregister(execsw_arg) 1330 const struct execsw *execsw_arg; 1331 { 1332 const struct execsw **es, **xs, **newexecsw; 1333 int count = 1; 1334 1335 if (execsw == NULL) 1336 panic("unregister with no handlers left?\n"); 1337 1338 for (es = execsw; *es; es++) { 1339 if (*es == execsw_arg) 1340 break; 1341 } 1342 if (*es == NULL) 1343 return (ENOENT); 1344 for (es = execsw; *es; es++) 1345 if (*es != execsw_arg) 1346 count++; 1347 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1348 if (newexecsw == NULL) 1349 return (ENOMEM); 1350 xs = newexecsw; 1351 for (es = execsw; *es; es++) 1352 if (*es != execsw_arg) 1353 *xs++ = *es; 1354 *xs = NULL; 1355 if (execsw) 1356 free(execsw, M_TEMP); 1357 execsw = newexecsw; 1358 return (0); 1359 }
Cache object: 31198ad3f7345a0755cce1319d941b9e
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