1 /* 2 * Copyright (c) 2005 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Jeffrey Hsu. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * 35 * Copyright (c) 1982, 1986, 1989, 1991, 1993 36 * The Regents of the University of California. All rights reserved. 37 * (c) UNIX System Laboratories, Inc. 38 * All or some portions of this file are derived from material licensed 39 * to the University of California by American Telephone and Telegraph 40 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 41 * the permission of UNIX System Laboratories, Inc. 42 * 43 * Redistribution and use in source and binary forms, with or without 44 * modification, are permitted provided that the following conditions 45 * are met: 46 * 1. Redistributions of source code must retain the above copyright 47 * notice, this list of conditions and the following disclaimer. 48 * 2. Redistributions in binary form must reproduce the above copyright 49 * notice, this list of conditions and the following disclaimer in the 50 * documentation and/or other materials provided with the distribution. 51 * 3. All advertising materials mentioning features or use of this software 52 * must display the following acknowledgement: 53 * This product includes software developed by the University of 54 * California, Berkeley and its contributors. 55 * 4. Neither the name of the University nor the names of its contributors 56 * may be used to endorse or promote products derived from this software 57 * without specific prior written permission. 58 * 59 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 60 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 61 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 62 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 63 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 64 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 65 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 66 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 67 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 68 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 69 * SUCH DAMAGE. 70 * 71 * @(#)kern_descrip.c 8.6 (Berkeley) 4/19/94 72 * $FreeBSD: src/sys/kern/kern_descrip.c,v 1.81.2.19 2004/02/28 00:43:31 tegge Exp $ 73 * $DragonFly: src/sys/kern/kern_descrip.c,v 1.79 2008/08/31 13:18:28 aggelos Exp $ 74 */ 75 76 #include "opt_compat.h" 77 #include <sys/param.h> 78 #include <sys/systm.h> 79 #include <sys/malloc.h> 80 #include <sys/sysproto.h> 81 #include <sys/conf.h> 82 #include <sys/device.h> 83 #include <sys/filedesc.h> 84 #include <sys/kernel.h> 85 #include <sys/sysctl.h> 86 #include <sys/vnode.h> 87 #include <sys/proc.h> 88 #include <sys/nlookup.h> 89 #include <sys/file.h> 90 #include <sys/stat.h> 91 #include <sys/filio.h> 92 #include <sys/fcntl.h> 93 #include <sys/unistd.h> 94 #include <sys/resourcevar.h> 95 #include <sys/event.h> 96 #include <sys/kern_syscall.h> 97 #include <sys/kcore.h> 98 #include <sys/kinfo.h> 99 #include <sys/un.h> 100 101 #include <vm/vm.h> 102 #include <vm/vm_extern.h> 103 104 #include <sys/thread2.h> 105 #include <sys/file2.h> 106 #include <sys/spinlock2.h> 107 108 static void fsetfd_locked(struct filedesc *fdp, struct file *fp, int fd); 109 static void fdreserve_locked (struct filedesc *fdp, int fd0, int incr); 110 static struct file *funsetfd_locked (struct filedesc *fdp, int fd); 111 static int checkfpclosed(struct filedesc *fdp, int fd, struct file *fp); 112 static void ffree(struct file *fp); 113 114 static MALLOC_DEFINE(M_FILEDESC, "file desc", "Open file descriptor table"); 115 static MALLOC_DEFINE(M_FILEDESC_TO_LEADER, "file desc to leader", 116 "file desc to leader structures"); 117 MALLOC_DEFINE(M_FILE, "file", "Open file structure"); 118 static MALLOC_DEFINE(M_SIGIO, "sigio", "sigio structures"); 119 120 static d_open_t fdopen; 121 #define NUMFDESC 64 122 123 #define CDEV_MAJOR 22 124 static struct dev_ops fildesc_ops = { 125 { "FD", CDEV_MAJOR, 0 }, 126 .d_open = fdopen, 127 }; 128 129 static int badfo_readwrite (struct file *fp, struct uio *uio, 130 struct ucred *cred, int flags); 131 static int badfo_ioctl (struct file *fp, u_long com, caddr_t data, 132 struct ucred *cred); 133 static int badfo_poll (struct file *fp, int events, struct ucred *cred); 134 static int badfo_kqfilter (struct file *fp, struct knote *kn); 135 static int badfo_stat (struct file *fp, struct stat *sb, struct ucred *cred); 136 static int badfo_close (struct file *fp); 137 static int badfo_shutdown (struct file *fp, int how); 138 139 /* 140 * Descriptor management. 141 */ 142 static struct filelist filehead = LIST_HEAD_INITIALIZER(&filehead); 143 static struct spinlock filehead_spin = SPINLOCK_INITIALIZER(&filehead_spin); 144 static int nfiles; /* actual number of open files */ 145 extern int cmask; 146 147 /* 148 * Fixup fd_freefile and fd_lastfile after a descriptor has been cleared. 149 * 150 * MPSAFE - must be called with fdp->fd_spin exclusively held 151 */ 152 static __inline 153 void 154 fdfixup_locked(struct filedesc *fdp, int fd) 155 { 156 if (fd < fdp->fd_freefile) { 157 fdp->fd_freefile = fd; 158 } 159 while (fdp->fd_lastfile >= 0 && 160 fdp->fd_files[fdp->fd_lastfile].fp == NULL && 161 fdp->fd_files[fdp->fd_lastfile].reserved == 0 162 ) { 163 --fdp->fd_lastfile; 164 } 165 } 166 167 /* 168 * System calls on descriptors. 169 * 170 * MPSAFE 171 */ 172 int 173 sys_getdtablesize(struct getdtablesize_args *uap) 174 { 175 struct proc *p = curproc; 176 struct plimit *limit = p->p_limit; 177 178 spin_lock_rd(&limit->p_spin); 179 uap->sysmsg_result = 180 min((int)limit->pl_rlimit[RLIMIT_NOFILE].rlim_cur, maxfilesperproc); 181 spin_unlock_rd(&limit->p_spin); 182 return (0); 183 } 184 185 /* 186 * Duplicate a file descriptor to a particular value. 187 * 188 * note: keep in mind that a potential race condition exists when closing 189 * descriptors from a shared descriptor table (via rfork). 190 * 191 * MPSAFE 192 */ 193 int 194 sys_dup2(struct dup2_args *uap) 195 { 196 int error; 197 198 error = kern_dup(DUP_FIXED, uap->from, uap->to, uap->sysmsg_fds); 199 200 return (error); 201 } 202 203 /* 204 * Duplicate a file descriptor. 205 * 206 * MPSAFE 207 */ 208 int 209 sys_dup(struct dup_args *uap) 210 { 211 int error; 212 213 error = kern_dup(DUP_VARIABLE, uap->fd, 0, uap->sysmsg_fds); 214 215 return (error); 216 } 217 218 /* 219 * MPALMOSTSAFE - acquires mplock for fp operations 220 */ 221 int 222 kern_fcntl(int fd, int cmd, union fcntl_dat *dat, struct ucred *cred) 223 { 224 struct thread *td = curthread; 225 struct proc *p = td->td_proc; 226 struct file *fp; 227 struct vnode *vp; 228 u_int newmin; 229 u_int oflags; 230 u_int nflags; 231 int tmp, error, flg = F_POSIX; 232 233 KKASSERT(p); 234 235 /* 236 * Operations on file descriptors that do not require a file pointer. 237 */ 238 switch (cmd) { 239 case F_GETFD: 240 error = fgetfdflags(p->p_fd, fd, &tmp); 241 if (error == 0) 242 dat->fc_cloexec = (tmp & UF_EXCLOSE) ? FD_CLOEXEC : 0; 243 return (error); 244 245 case F_SETFD: 246 if (dat->fc_cloexec & FD_CLOEXEC) 247 error = fsetfdflags(p->p_fd, fd, UF_EXCLOSE); 248 else 249 error = fclrfdflags(p->p_fd, fd, UF_EXCLOSE); 250 return (error); 251 case F_DUPFD: 252 newmin = dat->fc_fd; 253 error = kern_dup(DUP_VARIABLE, fd, newmin, &dat->fc_fd); 254 return (error); 255 default: 256 break; 257 } 258 259 /* 260 * Operations on file pointers 261 */ 262 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL) 263 return (EBADF); 264 265 get_mplock(); 266 switch (cmd) { 267 case F_GETFL: 268 dat->fc_flags = OFLAGS(fp->f_flag); 269 error = 0; 270 break; 271 272 case F_SETFL: 273 oflags = fp->f_flag; 274 nflags = FFLAGS(dat->fc_flags & ~O_ACCMODE) & FCNTLFLAGS; 275 nflags |= oflags & ~FCNTLFLAGS; 276 277 error = 0; 278 if (((nflags ^ oflags) & O_APPEND) && (oflags & FAPPENDONLY)) 279 error = EINVAL; 280 if (error == 0 && ((nflags ^ oflags) & FASYNC)) { 281 tmp = fp->f_flag & FASYNC; 282 error = fo_ioctl(fp, FIOASYNC, (caddr_t)&tmp, cred); 283 } 284 if (error == 0) 285 fp->f_flag = nflags; 286 break; 287 288 case F_GETOWN: 289 error = fo_ioctl(fp, FIOGETOWN, (caddr_t)&dat->fc_owner, cred); 290 break; 291 292 case F_SETOWN: 293 error = fo_ioctl(fp, FIOSETOWN, (caddr_t)&dat->fc_owner, cred); 294 break; 295 296 case F_SETLKW: 297 flg |= F_WAIT; 298 /* Fall into F_SETLK */ 299 300 case F_SETLK: 301 if (fp->f_type != DTYPE_VNODE) { 302 error = EBADF; 303 break; 304 } 305 vp = (struct vnode *)fp->f_data; 306 307 /* 308 * copyin/lockop may block 309 */ 310 if (dat->fc_flock.l_whence == SEEK_CUR) 311 dat->fc_flock.l_start += fp->f_offset; 312 313 switch (dat->fc_flock.l_type) { 314 case F_RDLCK: 315 if ((fp->f_flag & FREAD) == 0) { 316 error = EBADF; 317 break; 318 } 319 p->p_leader->p_flag |= P_ADVLOCK; 320 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK, 321 &dat->fc_flock, flg); 322 break; 323 case F_WRLCK: 324 if ((fp->f_flag & FWRITE) == 0) { 325 error = EBADF; 326 break; 327 } 328 p->p_leader->p_flag |= P_ADVLOCK; 329 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK, 330 &dat->fc_flock, flg); 331 break; 332 case F_UNLCK: 333 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK, 334 &dat->fc_flock, F_POSIX); 335 break; 336 default: 337 error = EINVAL; 338 break; 339 } 340 341 /* 342 * It is possible to race a close() on the descriptor while 343 * we were blocked getting the lock. If this occurs the 344 * close might not have caught the lock. 345 */ 346 if (checkfpclosed(p->p_fd, fd, fp)) { 347 dat->fc_flock.l_whence = SEEK_SET; 348 dat->fc_flock.l_start = 0; 349 dat->fc_flock.l_len = 0; 350 dat->fc_flock.l_type = F_UNLCK; 351 (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader, 352 F_UNLCK, &dat->fc_flock, F_POSIX); 353 } 354 break; 355 356 case F_GETLK: 357 if (fp->f_type != DTYPE_VNODE) { 358 error = EBADF; 359 break; 360 } 361 vp = (struct vnode *)fp->f_data; 362 /* 363 * copyin/lockop may block 364 */ 365 if (dat->fc_flock.l_type != F_RDLCK && 366 dat->fc_flock.l_type != F_WRLCK && 367 dat->fc_flock.l_type != F_UNLCK) { 368 error = EINVAL; 369 break; 370 } 371 if (dat->fc_flock.l_whence == SEEK_CUR) 372 dat->fc_flock.l_start += fp->f_offset; 373 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_GETLK, 374 &dat->fc_flock, F_POSIX); 375 break; 376 default: 377 error = EINVAL; 378 break; 379 } 380 rel_mplock(); 381 382 fdrop(fp); 383 return (error); 384 } 385 386 /* 387 * The file control system call. 388 * 389 * MPSAFE 390 */ 391 int 392 sys_fcntl(struct fcntl_args *uap) 393 { 394 union fcntl_dat dat; 395 int error; 396 397 switch (uap->cmd) { 398 case F_DUPFD: 399 dat.fc_fd = uap->arg; 400 break; 401 case F_SETFD: 402 dat.fc_cloexec = uap->arg; 403 break; 404 case F_SETFL: 405 dat.fc_flags = uap->arg; 406 break; 407 case F_SETOWN: 408 dat.fc_owner = uap->arg; 409 break; 410 case F_SETLKW: 411 case F_SETLK: 412 case F_GETLK: 413 error = copyin((caddr_t)uap->arg, &dat.fc_flock, 414 sizeof(struct flock)); 415 if (error) 416 return (error); 417 break; 418 } 419 420 error = kern_fcntl(uap->fd, uap->cmd, &dat, curproc->p_ucred); 421 422 if (error == 0) { 423 switch (uap->cmd) { 424 case F_DUPFD: 425 uap->sysmsg_result = dat.fc_fd; 426 break; 427 case F_GETFD: 428 uap->sysmsg_result = dat.fc_cloexec; 429 break; 430 case F_GETFL: 431 uap->sysmsg_result = dat.fc_flags; 432 break; 433 case F_GETOWN: 434 uap->sysmsg_result = dat.fc_owner; 435 case F_GETLK: 436 error = copyout(&dat.fc_flock, (caddr_t)uap->arg, 437 sizeof(struct flock)); 438 break; 439 } 440 } 441 442 return (error); 443 } 444 445 /* 446 * Common code for dup, dup2, and fcntl(F_DUPFD). 447 * 448 * The type flag can be either DUP_FIXED or DUP_VARIABLE. DUP_FIXED tells 449 * kern_dup() to destructively dup over an existing file descriptor if new 450 * is already open. DUP_VARIABLE tells kern_dup() to find the lowest 451 * unused file descriptor that is greater than or equal to new. 452 * 453 * MPSAFE 454 */ 455 int 456 kern_dup(enum dup_type type, int old, int new, int *res) 457 { 458 struct thread *td = curthread; 459 struct proc *p = td->td_proc; 460 struct filedesc *fdp = p->p_fd; 461 struct file *fp; 462 struct file *delfp; 463 int oldflags; 464 int holdleaders; 465 int error, newfd; 466 467 /* 468 * Verify that we have a valid descriptor to dup from and 469 * possibly to dup to. 470 */ 471 retry: 472 spin_lock_wr(&fdp->fd_spin); 473 if (new < 0 || new > p->p_rlimit[RLIMIT_NOFILE].rlim_cur || 474 new >= maxfilesperproc) { 475 spin_unlock_wr(&fdp->fd_spin); 476 return (EINVAL); 477 } 478 if ((unsigned)old >= fdp->fd_nfiles || fdp->fd_files[old].fp == NULL) { 479 spin_unlock_wr(&fdp->fd_spin); 480 return (EBADF); 481 } 482 if (type == DUP_FIXED && old == new) { 483 *res = new; 484 spin_unlock_wr(&fdp->fd_spin); 485 return (0); 486 } 487 fp = fdp->fd_files[old].fp; 488 oldflags = fdp->fd_files[old].fileflags; 489 fhold(fp); /* MPSAFE - can be called with a spinlock held */ 490 491 /* 492 * Allocate a new descriptor if DUP_VARIABLE, or expand the table 493 * if the requested descriptor is beyond the current table size. 494 * 495 * This can block. Retry if the source descriptor no longer matches 496 * or if our expectation in the expansion case races. 497 * 498 * If we are not expanding or allocating a new decriptor, then reset 499 * the target descriptor to a reserved state so we have a uniform 500 * setup for the next code block. 501 */ 502 if (type == DUP_VARIABLE || new >= fdp->fd_nfiles) { 503 spin_unlock_wr(&fdp->fd_spin); 504 error = fdalloc(p, new, &newfd); 505 spin_lock_wr(&fdp->fd_spin); 506 if (error) { 507 spin_unlock_wr(&fdp->fd_spin); 508 fdrop(fp); 509 return (error); 510 } 511 /* 512 * Check for ripout 513 */ 514 if (old >= fdp->fd_nfiles || fdp->fd_files[old].fp != fp) { 515 fsetfd_locked(fdp, NULL, newfd); 516 spin_unlock_wr(&fdp->fd_spin); 517 fdrop(fp); 518 goto retry; 519 } 520 /* 521 * Check for expansion race 522 */ 523 if (type != DUP_VARIABLE && new != newfd) { 524 fsetfd_locked(fdp, NULL, newfd); 525 spin_unlock_wr(&fdp->fd_spin); 526 fdrop(fp); 527 goto retry; 528 } 529 /* 530 * Check for ripout, newfd reused old (this case probably 531 * can't occur). 532 */ 533 if (old == newfd) { 534 fsetfd_locked(fdp, NULL, newfd); 535 spin_unlock_wr(&fdp->fd_spin); 536 fdrop(fp); 537 goto retry; 538 } 539 new = newfd; 540 delfp = NULL; 541 } else { 542 if (fdp->fd_files[new].reserved) { 543 spin_unlock_wr(&fdp->fd_spin); 544 fdrop(fp); 545 kprintf("Warning: dup(): target descriptor %d is reserved, waiting for it to be resolved\n", new); 546 tsleep(fdp, 0, "fdres", hz); 547 goto retry; 548 } 549 550 /* 551 * If the target descriptor was never allocated we have 552 * to allocate it. If it was we have to clean out the 553 * old descriptor. delfp inherits the ref from the 554 * descriptor table. 555 */ 556 delfp = fdp->fd_files[new].fp; 557 fdp->fd_files[new].fp = NULL; 558 fdp->fd_files[new].reserved = 1; 559 if (delfp == NULL) { 560 fdreserve_locked(fdp, new, 1); 561 if (new > fdp->fd_lastfile) 562 fdp->fd_lastfile = new; 563 } 564 565 } 566 567 /* 568 * NOTE: still holding an exclusive spinlock 569 */ 570 571 /* 572 * If a descriptor is being overwritten we may hve to tell 573 * fdfree() to sleep to ensure that all relevant process 574 * leaders can be traversed in closef(). 575 */ 576 if (delfp != NULL && p->p_fdtol != NULL) { 577 fdp->fd_holdleaderscount++; 578 holdleaders = 1; 579 } else { 580 holdleaders = 0; 581 } 582 KASSERT(delfp == NULL || type == DUP_FIXED, 583 ("dup() picked an open file")); 584 585 /* 586 * Duplicate the source descriptor, update lastfile. If the new 587 * descriptor was not allocated and we aren't replacing an existing 588 * descriptor we have to mark the descriptor as being in use. 589 * 590 * The fd_files[] array inherits fp's hold reference. 591 */ 592 fsetfd_locked(fdp, fp, new); 593 fdp->fd_files[new].fileflags = oldflags & ~UF_EXCLOSE; 594 spin_unlock_wr(&fdp->fd_spin); 595 fdrop(fp); 596 *res = new; 597 598 /* 599 * If we dup'd over a valid file, we now own the reference to it 600 * and must dispose of it using closef() semantics (as if a 601 * close() were performed on it). 602 */ 603 if (delfp) { 604 closef(delfp, p); 605 if (holdleaders) { 606 spin_lock_wr(&fdp->fd_spin); 607 fdp->fd_holdleaderscount--; 608 if (fdp->fd_holdleaderscount == 0 && 609 fdp->fd_holdleaderswakeup != 0) { 610 fdp->fd_holdleaderswakeup = 0; 611 spin_unlock_wr(&fdp->fd_spin); 612 wakeup(&fdp->fd_holdleaderscount); 613 } else { 614 spin_unlock_wr(&fdp->fd_spin); 615 } 616 } 617 } 618 return (0); 619 } 620 621 /* 622 * If sigio is on the list associated with a process or process group, 623 * disable signalling from the device, remove sigio from the list and 624 * free sigio. 625 */ 626 void 627 funsetown(struct sigio *sigio) 628 { 629 if (sigio == NULL) 630 return; 631 crit_enter(); 632 *(sigio->sio_myref) = NULL; 633 crit_exit(); 634 if (sigio->sio_pgid < 0) { 635 SLIST_REMOVE(&sigio->sio_pgrp->pg_sigiolst, sigio, 636 sigio, sio_pgsigio); 637 } else /* if ((*sigiop)->sio_pgid > 0) */ { 638 SLIST_REMOVE(&sigio->sio_proc->p_sigiolst, sigio, 639 sigio, sio_pgsigio); 640 } 641 crfree(sigio->sio_ucred); 642 kfree(sigio, M_SIGIO); 643 } 644 645 /* Free a list of sigio structures. */ 646 void 647 funsetownlst(struct sigiolst *sigiolst) 648 { 649 struct sigio *sigio; 650 651 while ((sigio = SLIST_FIRST(sigiolst)) != NULL) 652 funsetown(sigio); 653 } 654 655 /* 656 * This is common code for FIOSETOWN ioctl called by fcntl(fd, F_SETOWN, arg). 657 * 658 * After permission checking, add a sigio structure to the sigio list for 659 * the process or process group. 660 */ 661 int 662 fsetown(pid_t pgid, struct sigio **sigiop) 663 { 664 struct proc *proc; 665 struct pgrp *pgrp; 666 struct sigio *sigio; 667 668 if (pgid == 0) { 669 funsetown(*sigiop); 670 return (0); 671 } 672 if (pgid > 0) { 673 proc = pfind(pgid); 674 if (proc == NULL) 675 return (ESRCH); 676 677 /* 678 * Policy - Don't allow a process to FSETOWN a process 679 * in another session. 680 * 681 * Remove this test to allow maximum flexibility or 682 * restrict FSETOWN to the current process or process 683 * group for maximum safety. 684 */ 685 if (proc->p_session != curproc->p_session) 686 return (EPERM); 687 688 pgrp = NULL; 689 } else /* if (pgid < 0) */ { 690 pgrp = pgfind(-pgid); 691 if (pgrp == NULL) 692 return (ESRCH); 693 694 /* 695 * Policy - Don't allow a process to FSETOWN a process 696 * in another session. 697 * 698 * Remove this test to allow maximum flexibility or 699 * restrict FSETOWN to the current process or process 700 * group for maximum safety. 701 */ 702 if (pgrp->pg_session != curproc->p_session) 703 return (EPERM); 704 705 proc = NULL; 706 } 707 funsetown(*sigiop); 708 sigio = kmalloc(sizeof(struct sigio), M_SIGIO, M_WAITOK); 709 if (pgid > 0) { 710 SLIST_INSERT_HEAD(&proc->p_sigiolst, sigio, sio_pgsigio); 711 sigio->sio_proc = proc; 712 } else { 713 SLIST_INSERT_HEAD(&pgrp->pg_sigiolst, sigio, sio_pgsigio); 714 sigio->sio_pgrp = pgrp; 715 } 716 sigio->sio_pgid = pgid; 717 sigio->sio_ucred = crhold(curproc->p_ucred); 718 /* It would be convenient if p_ruid was in ucred. */ 719 sigio->sio_ruid = curproc->p_ucred->cr_ruid; 720 sigio->sio_myref = sigiop; 721 crit_enter(); 722 *sigiop = sigio; 723 crit_exit(); 724 return (0); 725 } 726 727 /* 728 * This is common code for FIOGETOWN ioctl called by fcntl(fd, F_GETOWN, arg). 729 */ 730 pid_t 731 fgetown(struct sigio *sigio) 732 { 733 return (sigio != NULL ? sigio->sio_pgid : 0); 734 } 735 736 /* 737 * Close many file descriptors. 738 * 739 * MPSAFE 740 */ 741 int 742 sys_closefrom(struct closefrom_args *uap) 743 { 744 return(kern_closefrom(uap->fd)); 745 } 746 747 /* 748 * Close all file descriptors greater then or equal to fd 749 * 750 * MPSAFE 751 */ 752 int 753 kern_closefrom(int fd) 754 { 755 struct thread *td = curthread; 756 struct proc *p = td->td_proc; 757 struct filedesc *fdp; 758 759 KKASSERT(p); 760 fdp = p->p_fd; 761 762 if (fd < 0) 763 return (EINVAL); 764 765 /* 766 * NOTE: This function will skip unassociated descriptors and 767 * reserved descriptors that have not yet been assigned. 768 * fd_lastfile can change as a side effect of kern_close(). 769 */ 770 spin_lock_wr(&fdp->fd_spin); 771 while (fd <= fdp->fd_lastfile) { 772 if (fdp->fd_files[fd].fp != NULL) { 773 spin_unlock_wr(&fdp->fd_spin); 774 /* ok if this races another close */ 775 if (kern_close(fd) == EINTR) 776 return (EINTR); 777 spin_lock_wr(&fdp->fd_spin); 778 } 779 ++fd; 780 } 781 spin_unlock_wr(&fdp->fd_spin); 782 return (0); 783 } 784 785 /* 786 * Close a file descriptor. 787 * 788 * MPSAFE 789 */ 790 int 791 sys_close(struct close_args *uap) 792 { 793 return(kern_close(uap->fd)); 794 } 795 796 /* 797 * MPALMOSTSAFE - acquires mplock around knote_fdclose() calls 798 */ 799 int 800 kern_close(int fd) 801 { 802 struct thread *td = curthread; 803 struct proc *p = td->td_proc; 804 struct filedesc *fdp; 805 struct file *fp; 806 int error; 807 int holdleaders; 808 809 KKASSERT(p); 810 fdp = p->p_fd; 811 812 spin_lock_wr(&fdp->fd_spin); 813 if ((fp = funsetfd_locked(fdp, fd)) == NULL) { 814 spin_unlock_wr(&fdp->fd_spin); 815 return (EBADF); 816 } 817 holdleaders = 0; 818 if (p->p_fdtol != NULL) { 819 /* 820 * Ask fdfree() to sleep to ensure that all relevant 821 * process leaders can be traversed in closef(). 822 */ 823 fdp->fd_holdleaderscount++; 824 holdleaders = 1; 825 } 826 827 /* 828 * we now hold the fp reference that used to be owned by the descriptor 829 * array. 830 */ 831 spin_unlock_wr(&fdp->fd_spin); 832 if (fd < fdp->fd_knlistsize) { 833 get_mplock(); 834 if (fd < fdp->fd_knlistsize) 835 knote_fdclose(p, fd); 836 rel_mplock(); 837 } 838 error = closef(fp, p); 839 if (holdleaders) { 840 spin_lock_wr(&fdp->fd_spin); 841 fdp->fd_holdleaderscount--; 842 if (fdp->fd_holdleaderscount == 0 && 843 fdp->fd_holdleaderswakeup != 0) { 844 fdp->fd_holdleaderswakeup = 0; 845 spin_unlock_wr(&fdp->fd_spin); 846 wakeup(&fdp->fd_holdleaderscount); 847 } else { 848 spin_unlock_wr(&fdp->fd_spin); 849 } 850 } 851 return (error); 852 } 853 854 /* 855 * shutdown_args(int fd, int how) 856 */ 857 int 858 kern_shutdown(int fd, int how) 859 { 860 struct thread *td = curthread; 861 struct proc *p = td->td_proc; 862 struct file *fp; 863 int error; 864 865 KKASSERT(p); 866 867 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL) 868 return (EBADF); 869 error = fo_shutdown(fp, how); 870 fdrop(fp); 871 872 return (error); 873 } 874 875 int 876 sys_shutdown(struct shutdown_args *uap) 877 { 878 int error; 879 880 error = kern_shutdown(uap->s, uap->how); 881 882 return (error); 883 } 884 885 int 886 kern_fstat(int fd, struct stat *ub) 887 { 888 struct thread *td = curthread; 889 struct proc *p = td->td_proc; 890 struct file *fp; 891 int error; 892 893 KKASSERT(p); 894 895 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL) 896 return (EBADF); 897 error = fo_stat(fp, ub, p->p_ucred); 898 fdrop(fp); 899 900 return (error); 901 } 902 903 /* 904 * Return status information about a file descriptor. 905 */ 906 int 907 sys_fstat(struct fstat_args *uap) 908 { 909 struct stat st; 910 int error; 911 912 error = kern_fstat(uap->fd, &st); 913 914 if (error == 0) 915 error = copyout(&st, uap->sb, sizeof(st)); 916 return (error); 917 } 918 919 /* 920 * Return pathconf information about a file descriptor. 921 */ 922 /* ARGSUSED */ 923 int 924 sys_fpathconf(struct fpathconf_args *uap) 925 { 926 struct thread *td = curthread; 927 struct proc *p = td->td_proc; 928 struct file *fp; 929 struct vnode *vp; 930 int error = 0; 931 932 KKASSERT(p); 933 934 if ((fp = holdfp(p->p_fd, uap->fd, -1)) == NULL) 935 return (EBADF); 936 937 switch (fp->f_type) { 938 case DTYPE_PIPE: 939 case DTYPE_SOCKET: 940 if (uap->name != _PC_PIPE_BUF) { 941 error = EINVAL; 942 } else { 943 uap->sysmsg_result = PIPE_BUF; 944 error = 0; 945 } 946 break; 947 case DTYPE_FIFO: 948 case DTYPE_VNODE: 949 vp = (struct vnode *)fp->f_data; 950 error = VOP_PATHCONF(vp, uap->name, uap->sysmsg_fds); 951 break; 952 default: 953 error = EOPNOTSUPP; 954 break; 955 } 956 fdrop(fp); 957 return(error); 958 } 959 960 static int fdexpand; 961 SYSCTL_INT(_debug, OID_AUTO, fdexpand, CTLFLAG_RD, &fdexpand, 0, ""); 962 963 /* 964 * Grow the file table so it can hold through descriptor (want). 965 * 966 * The fdp's spinlock must be held exclusively on entry and may be held 967 * exclusively on return. The spinlock may be cycled by the routine. 968 * 969 * MPSAFE 970 */ 971 static void 972 fdgrow_locked(struct filedesc *fdp, int want) 973 { 974 struct fdnode *newfiles; 975 struct fdnode *oldfiles; 976 int nf, extra; 977 978 nf = fdp->fd_nfiles; 979 do { 980 /* nf has to be of the form 2^n - 1 */ 981 nf = 2 * nf + 1; 982 } while (nf <= want); 983 984 spin_unlock_wr(&fdp->fd_spin); 985 newfiles = kmalloc(nf * sizeof(struct fdnode), M_FILEDESC, M_WAITOK); 986 spin_lock_wr(&fdp->fd_spin); 987 988 /* 989 * We could have raced another extend while we were not holding 990 * the spinlock. 991 */ 992 if (fdp->fd_nfiles >= nf) { 993 spin_unlock_wr(&fdp->fd_spin); 994 kfree(newfiles, M_FILEDESC); 995 spin_lock_wr(&fdp->fd_spin); 996 return; 997 } 998 /* 999 * Copy the existing ofile and ofileflags arrays 1000 * and zero the new portion of each array. 1001 */ 1002 extra = nf - fdp->fd_nfiles; 1003 bcopy(fdp->fd_files, newfiles, fdp->fd_nfiles * sizeof(struct fdnode)); 1004 bzero(&newfiles[fdp->fd_nfiles], extra * sizeof(struct fdnode)); 1005 1006 oldfiles = fdp->fd_files; 1007 fdp->fd_files = newfiles; 1008 fdp->fd_nfiles = nf; 1009 1010 if (oldfiles != fdp->fd_builtin_files) { 1011 spin_unlock_wr(&fdp->fd_spin); 1012 kfree(oldfiles, M_FILEDESC); 1013 spin_lock_wr(&fdp->fd_spin); 1014 } 1015 fdexpand++; 1016 } 1017 1018 /* 1019 * Number of nodes in right subtree, including the root. 1020 */ 1021 static __inline int 1022 right_subtree_size(int n) 1023 { 1024 return (n ^ (n | (n + 1))); 1025 } 1026 1027 /* 1028 * Bigger ancestor. 1029 */ 1030 static __inline int 1031 right_ancestor(int n) 1032 { 1033 return (n | (n + 1)); 1034 } 1035 1036 /* 1037 * Smaller ancestor. 1038 */ 1039 static __inline int 1040 left_ancestor(int n) 1041 { 1042 return ((n & (n + 1)) - 1); 1043 } 1044 1045 /* 1046 * Traverse the in-place binary tree buttom-up adjusting the allocation 1047 * count so scans can determine where free descriptors are located. 1048 * 1049 * MPSAFE - caller must be holding an exclusive spinlock on fdp 1050 */ 1051 static 1052 void 1053 fdreserve_locked(struct filedesc *fdp, int fd, int incr) 1054 { 1055 while (fd >= 0) { 1056 fdp->fd_files[fd].allocated += incr; 1057 KKASSERT(fdp->fd_files[fd].allocated >= 0); 1058 fd = left_ancestor(fd); 1059 } 1060 } 1061 1062 /* 1063 * Reserve a file descriptor for the process. If no error occurs, the 1064 * caller MUST at some point call fsetfd() or assign a file pointer 1065 * or dispose of the reservation. 1066 * 1067 * MPSAFE 1068 */ 1069 int 1070 fdalloc(struct proc *p, int want, int *result) 1071 { 1072 struct filedesc *fdp = p->p_fd; 1073 int fd, rsize, rsum, node, lim; 1074 1075 spin_lock_rd(&p->p_limit->p_spin); 1076 lim = min((int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur, maxfilesperproc); 1077 spin_unlock_rd(&p->p_limit->p_spin); 1078 if (want >= lim) 1079 return (EMFILE); 1080 spin_lock_wr(&fdp->fd_spin); 1081 if (want >= fdp->fd_nfiles) 1082 fdgrow_locked(fdp, want); 1083 1084 /* 1085 * Search for a free descriptor starting at the higher 1086 * of want or fd_freefile. If that fails, consider 1087 * expanding the ofile array. 1088 * 1089 * NOTE! the 'allocated' field is a cumulative recursive allocation 1090 * count. If we happen to see a value of 0 then we can shortcut 1091 * our search. Otherwise we run through through the tree going 1092 * down branches we know have free descriptor(s) until we hit a 1093 * leaf node. The leaf node will be free but will not necessarily 1094 * have an allocated field of 0. 1095 */ 1096 retry: 1097 /* move up the tree looking for a subtree with a free node */ 1098 for (fd = max(want, fdp->fd_freefile); fd < min(fdp->fd_nfiles, lim); 1099 fd = right_ancestor(fd)) { 1100 if (fdp->fd_files[fd].allocated == 0) 1101 goto found; 1102 1103 rsize = right_subtree_size(fd); 1104 if (fdp->fd_files[fd].allocated == rsize) 1105 continue; /* right subtree full */ 1106 1107 /* 1108 * Free fd is in the right subtree of the tree rooted at fd. 1109 * Call that subtree R. Look for the smallest (leftmost) 1110 * subtree of R with an unallocated fd: continue moving 1111 * down the left branch until encountering a full left 1112 * subtree, then move to the right. 1113 */ 1114 for (rsum = 0, rsize /= 2; rsize > 0; rsize /= 2) { 1115 node = fd + rsize; 1116 rsum += fdp->fd_files[node].allocated; 1117 if (fdp->fd_files[fd].allocated == rsum + rsize) { 1118 fd = node; /* move to the right */ 1119 if (fdp->fd_files[node].allocated == 0) 1120 goto found; 1121 rsum = 0; 1122 } 1123 } 1124 goto found; 1125 } 1126 1127 /* 1128 * No space in current array. Expand? 1129 */ 1130 if (fdp->fd_nfiles >= lim) { 1131 spin_unlock_wr(&fdp->fd_spin); 1132 return (EMFILE); 1133 } 1134 fdgrow_locked(fdp, want); 1135 goto retry; 1136 1137 found: 1138 KKASSERT(fd < fdp->fd_nfiles); 1139 if (fd > fdp->fd_lastfile) 1140 fdp->fd_lastfile = fd; 1141 if (want <= fdp->fd_freefile) 1142 fdp->fd_freefile = fd; 1143 *result = fd; 1144 KKASSERT(fdp->fd_files[fd].fp == NULL); 1145 KKASSERT(fdp->fd_files[fd].reserved == 0); 1146 fdp->fd_files[fd].fileflags = 0; 1147 fdp->fd_files[fd].reserved = 1; 1148 fdreserve_locked(fdp, fd, 1); 1149 spin_unlock_wr(&fdp->fd_spin); 1150 return (0); 1151 } 1152 1153 /* 1154 * Check to see whether n user file descriptors 1155 * are available to the process p. 1156 * 1157 * MPSAFE 1158 */ 1159 int 1160 fdavail(struct proc *p, int n) 1161 { 1162 struct filedesc *fdp = p->p_fd; 1163 struct fdnode *fdnode; 1164 int i, lim, last; 1165 1166 spin_lock_rd(&p->p_limit->p_spin); 1167 lim = min((int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur, maxfilesperproc); 1168 spin_unlock_rd(&p->p_limit->p_spin); 1169 1170 spin_lock_rd(&fdp->fd_spin); 1171 if ((i = lim - fdp->fd_nfiles) > 0 && (n -= i) <= 0) { 1172 spin_unlock_rd(&fdp->fd_spin); 1173 return (1); 1174 } 1175 last = min(fdp->fd_nfiles, lim); 1176 fdnode = &fdp->fd_files[fdp->fd_freefile]; 1177 for (i = last - fdp->fd_freefile; --i >= 0; ++fdnode) { 1178 if (fdnode->fp == NULL && --n <= 0) { 1179 spin_unlock_rd(&fdp->fd_spin); 1180 return (1); 1181 } 1182 } 1183 spin_unlock_rd(&fdp->fd_spin); 1184 return (0); 1185 } 1186 1187 /* 1188 * Revoke open descriptors referencing (f_data, f_type) 1189 * 1190 * Any revoke executed within a prison is only able to 1191 * revoke descriptors for processes within that prison. 1192 * 1193 * Returns 0 on success or an error code. 1194 */ 1195 struct fdrevoke_info { 1196 void *data; 1197 short type; 1198 short unused; 1199 int count; 1200 int intransit; 1201 struct ucred *cred; 1202 struct file *nfp; 1203 }; 1204 1205 static int fdrevoke_check_callback(struct file *fp, void *vinfo); 1206 static int fdrevoke_proc_callback(struct proc *p, void *vinfo); 1207 1208 int 1209 fdrevoke(void *f_data, short f_type, struct ucred *cred) 1210 { 1211 struct fdrevoke_info info; 1212 int error; 1213 1214 bzero(&info, sizeof(info)); 1215 info.data = f_data; 1216 info.type = f_type; 1217 info.cred = cred; 1218 error = falloc(NULL, &info.nfp, NULL); 1219 if (error) 1220 return (error); 1221 1222 /* 1223 * Scan the file pointer table once. dups do not dup file pointers, 1224 * only descriptors, so there is no leak. Set FREVOKED on the fps 1225 * being revoked. 1226 */ 1227 allfiles_scan_exclusive(fdrevoke_check_callback, &info); 1228 1229 /* 1230 * If any fps were marked track down the related descriptors 1231 * and close them. Any dup()s at this point will notice 1232 * the FREVOKED already set in the fp and do the right thing. 1233 * 1234 * Any fps with non-zero msgcounts (aka sent over a unix-domain 1235 * socket) bumped the intransit counter and will require a 1236 * scan. Races against fps leaving the socket are closed by 1237 * the socket code checking for FREVOKED. 1238 */ 1239 if (info.count) 1240 allproc_scan(fdrevoke_proc_callback, &info); 1241 if (info.intransit) 1242 unp_revoke_gc(info.nfp); 1243 fdrop(info.nfp); 1244 return(0); 1245 } 1246 1247 /* 1248 * Locate matching file pointers directly. 1249 */ 1250 static int 1251 fdrevoke_check_callback(struct file *fp, void *vinfo) 1252 { 1253 struct fdrevoke_info *info = vinfo; 1254 1255 /* 1256 * File pointers already flagged for revokation are skipped. 1257 */ 1258 if (fp->f_flag & FREVOKED) 1259 return(0); 1260 1261 /* 1262 * If revoking from a prison file pointers created outside of 1263 * that prison, or file pointers without creds, cannot be revoked. 1264 */ 1265 if (info->cred->cr_prison && 1266 (fp->f_cred == NULL || 1267 info->cred->cr_prison != fp->f_cred->cr_prison)) { 1268 return(0); 1269 } 1270 1271 /* 1272 * If the file pointer matches then mark it for revocation. The 1273 * flag is currently only used by unp_revoke_gc(). 1274 * 1275 * info->count is a heuristic and can race in a SMP environment. 1276 */ 1277 if (info->data == fp->f_data && info->type == fp->f_type) { 1278 atomic_set_int(&fp->f_flag, FREVOKED); 1279 info->count += fp->f_count; 1280 if (fp->f_msgcount) 1281 ++info->intransit; 1282 } 1283 return(0); 1284 } 1285 1286 /* 1287 * Locate matching file pointers via process descriptor tables. 1288 */ 1289 static int 1290 fdrevoke_proc_callback(struct proc *p, void *vinfo) 1291 { 1292 struct fdrevoke_info *info = vinfo; 1293 struct filedesc *fdp; 1294 struct file *fp; 1295 int n; 1296 1297 if (p->p_stat == SIDL || p->p_stat == SZOMB) 1298 return(0); 1299 if (info->cred->cr_prison && 1300 info->cred->cr_prison != p->p_ucred->cr_prison) { 1301 return(0); 1302 } 1303 1304 /* 1305 * If the controlling terminal of the process matches the 1306 * vnode being revoked we clear the controlling terminal. 1307 * 1308 * The normal spec_close() may not catch this because it 1309 * uses curproc instead of p. 1310 */ 1311 if (p->p_session && info->type == DTYPE_VNODE && 1312 info->data == p->p_session->s_ttyvp) { 1313 p->p_session->s_ttyvp = NULL; 1314 vrele(info->data); 1315 } 1316 1317 /* 1318 * Locate and close any matching file descriptors. 1319 */ 1320 if ((fdp = p->p_fd) == NULL) 1321 return(0); 1322 spin_lock_wr(&fdp->fd_spin); 1323 for (n = 0; n < fdp->fd_nfiles; ++n) { 1324 if ((fp = fdp->fd_files[n].fp) == NULL) 1325 continue; 1326 if (fp->f_flag & FREVOKED) { 1327 fhold(info->nfp); 1328 fdp->fd_files[n].fp = info->nfp; 1329 spin_unlock_wr(&fdp->fd_spin); 1330 closef(fp, p); 1331 spin_lock_wr(&fdp->fd_spin); 1332 --info->count; 1333 } 1334 } 1335 spin_unlock_wr(&fdp->fd_spin); 1336 return(0); 1337 } 1338 1339 /* 1340 * falloc: 1341 * Create a new open file structure and reserve a file decriptor 1342 * for the process that refers to it. 1343 * 1344 * Root creds are checked using p, or assumed if p is NULL. If 1345 * resultfd is non-NULL then p must also be non-NULL. No file 1346 * descriptor is reserved if resultfd is NULL. 1347 * 1348 * A file pointer with a refcount of 1 is returned. Note that the 1349 * file pointer is NOT associated with the descriptor. If falloc 1350 * returns success, fsetfd() MUST be called to either associate the 1351 * file pointer or clear the reservation. 1352 * 1353 * MPSAFE 1354 */ 1355 int 1356 falloc(struct proc *p, struct file **resultfp, int *resultfd) 1357 { 1358 static struct timeval lastfail; 1359 static int curfail; 1360 struct file *fp; 1361 int error; 1362 1363 fp = NULL; 1364 1365 /* 1366 * Handle filetable full issues and root overfill. 1367 */ 1368 if (nfiles >= maxfiles - maxfilesrootres && 1369 ((p && p->p_ucred->cr_ruid != 0) || nfiles >= maxfiles)) { 1370 if (ppsratecheck(&lastfail, &curfail, 1)) { 1371 kprintf("kern.maxfiles limit exceeded by uid %d, please see tuning(7).\n", 1372 (p ? p->p_ucred->cr_ruid : -1)); 1373 } 1374 error = ENFILE; 1375 goto done; 1376 } 1377 1378 /* 1379 * Allocate a new file descriptor. 1380 */ 1381 fp = kmalloc(sizeof(struct file), M_FILE, M_WAITOK | M_ZERO); 1382 spin_init(&fp->f_spin); 1383 fp->f_count = 1; 1384 fp->f_ops = &badfileops; 1385 fp->f_seqcount = 1; 1386 if (p) 1387 fp->f_cred = crhold(p->p_ucred); 1388 else 1389 fp->f_cred = crhold(proc0.p_ucred); 1390 spin_lock_wr(&filehead_spin); 1391 nfiles++; 1392 LIST_INSERT_HEAD(&filehead, fp, f_list); 1393 spin_unlock_wr(&filehead_spin); 1394 if (resultfd) { 1395 if ((error = fdalloc(p, 0, resultfd)) != 0) { 1396 fdrop(fp); 1397 fp = NULL; 1398 } 1399 } else { 1400 error = 0; 1401 } 1402 done: 1403 *resultfp = fp; 1404 return (error); 1405 } 1406 1407 /* 1408 * MPSAFE 1409 */ 1410 static 1411 int 1412 checkfpclosed(struct filedesc *fdp, int fd, struct file *fp) 1413 { 1414 int error; 1415 1416 spin_lock_rd(&fdp->fd_spin); 1417 if ((unsigned) fd >= fdp->fd_nfiles || fp != fdp->fd_files[fd].fp) 1418 error = EBADF; 1419 else 1420 error = 0; 1421 spin_unlock_rd(&fdp->fd_spin); 1422 return (error); 1423 } 1424 1425 /* 1426 * Associate a file pointer with a previously reserved file descriptor. 1427 * This function always succeeds. 1428 * 1429 * If fp is NULL, the file descriptor is returned to the pool. 1430 */ 1431 1432 /* 1433 * MPSAFE (exclusive spinlock must be held on call) 1434 */ 1435 static void 1436 fsetfd_locked(struct filedesc *fdp, struct file *fp, int fd) 1437 { 1438 KKASSERT((unsigned)fd < fdp->fd_nfiles); 1439 KKASSERT(fdp->fd_files[fd].reserved != 0); 1440 if (fp) { 1441 fhold(fp); 1442 fdp->fd_files[fd].fp = fp; 1443 fdp->fd_files[fd].reserved = 0; 1444 if (fp->f_type == DTYPE_KQUEUE) { 1445 if (fdp->fd_knlistsize < 0) 1446 fdp->fd_knlistsize = 0; 1447 } 1448 } else { 1449 fdp->fd_files[fd].reserved = 0; 1450 fdreserve_locked(fdp, fd, -1); 1451 fdfixup_locked(fdp, fd); 1452 } 1453 } 1454 1455 /* 1456 * MPSAFE 1457 */ 1458 void 1459 fsetfd(struct proc *p, struct file *fp, int fd) 1460 { 1461 struct filedesc *fdp = p->p_fd; 1462 1463 spin_lock_wr(&fdp->fd_spin); 1464 fsetfd_locked(fdp, fp, fd); 1465 spin_unlock_wr(&fdp->fd_spin); 1466 } 1467 1468 /* 1469 * MPSAFE (exclusive spinlock must be held on call) 1470 */ 1471 static 1472 struct file * 1473 funsetfd_locked(struct filedesc *fdp, int fd) 1474 { 1475 struct file *fp; 1476 1477 if ((unsigned)fd >= fdp->fd_nfiles) 1478 return (NULL); 1479 if ((fp = fdp->fd_files[fd].fp) == NULL) 1480 return (NULL); 1481 fdp->fd_files[fd].fp = NULL; 1482 fdp->fd_files[fd].fileflags = 0; 1483 1484 fdreserve_locked(fdp, fd, -1); 1485 fdfixup_locked(fdp, fd); 1486 return(fp); 1487 } 1488 1489 /* 1490 * MPSAFE 1491 */ 1492 int 1493 fgetfdflags(struct filedesc *fdp, int fd, int *flagsp) 1494 { 1495 int error; 1496 1497 spin_lock_rd(&fdp->fd_spin); 1498 if (((u_int)fd) >= fdp->fd_nfiles) { 1499 error = EBADF; 1500 } else if (fdp->fd_files[fd].fp == NULL) { 1501 error = EBADF; 1502 } else { 1503 *flagsp = fdp->fd_files[fd].fileflags; 1504 error = 0; 1505 } 1506 spin_unlock_rd(&fdp->fd_spin); 1507 return (error); 1508 } 1509 1510 /* 1511 * MPSAFE 1512 */ 1513 int 1514 fsetfdflags(struct filedesc *fdp, int fd, int add_flags) 1515 { 1516 int error; 1517 1518 spin_lock_wr(&fdp->fd_spin); 1519 if (((u_int)fd) >= fdp->fd_nfiles) { 1520 error = EBADF; 1521 } else if (fdp->fd_files[fd].fp == NULL) { 1522 error = EBADF; 1523 } else { 1524 fdp->fd_files[fd].fileflags |= add_flags; 1525 error = 0; 1526 } 1527 spin_unlock_wr(&fdp->fd_spin); 1528 return (error); 1529 } 1530 1531 /* 1532 * MPSAFE 1533 */ 1534 int 1535 fclrfdflags(struct filedesc *fdp, int fd, int rem_flags) 1536 { 1537 int error; 1538 1539 spin_lock_wr(&fdp->fd_spin); 1540 if (((u_int)fd) >= fdp->fd_nfiles) { 1541 error = EBADF; 1542 } else if (fdp->fd_files[fd].fp == NULL) { 1543 error = EBADF; 1544 } else { 1545 fdp->fd_files[fd].fileflags &= ~rem_flags; 1546 error = 0; 1547 } 1548 spin_unlock_wr(&fdp->fd_spin); 1549 return (error); 1550 } 1551 1552 void 1553 fsetcred(struct file *fp, struct ucred *cr) 1554 { 1555 crhold(cr); 1556 crfree(fp->f_cred); 1557 fp->f_cred = cr; 1558 } 1559 1560 /* 1561 * Free a file descriptor. 1562 */ 1563 static 1564 void 1565 ffree(struct file *fp) 1566 { 1567 KASSERT((fp->f_count == 0), ("ffree: fp_fcount not 0!")); 1568 spin_lock_wr(&filehead_spin); 1569 LIST_REMOVE(fp, f_list); 1570 nfiles--; 1571 spin_unlock_wr(&filehead_spin); 1572 crfree(fp->f_cred); 1573 if (fp->f_nchandle.ncp) 1574 cache_drop(&fp->f_nchandle); 1575 kfree(fp, M_FILE); 1576 } 1577 1578 /* 1579 * called from init_main, initialize filedesc0 for proc0. 1580 */ 1581 void 1582 fdinit_bootstrap(struct proc *p0, struct filedesc *fdp0, int cmask) 1583 { 1584 p0->p_fd = fdp0; 1585 p0->p_fdtol = NULL; 1586 fdp0->fd_refcnt = 1; 1587 fdp0->fd_cmask = cmask; 1588 fdp0->fd_files = fdp0->fd_builtin_files; 1589 fdp0->fd_nfiles = NDFILE; 1590 fdp0->fd_lastfile = -1; 1591 spin_init(&fdp0->fd_spin); 1592 } 1593 1594 /* 1595 * Build a new filedesc structure. 1596 * 1597 * NOT MPSAFE (vref) 1598 */ 1599 struct filedesc * 1600 fdinit(struct proc *p) 1601 { 1602 struct filedesc *newfdp; 1603 struct filedesc *fdp = p->p_fd; 1604 1605 newfdp = kmalloc(sizeof(struct filedesc), M_FILEDESC, M_WAITOK|M_ZERO); 1606 spin_lock_rd(&fdp->fd_spin); 1607 if (fdp->fd_cdir) { 1608 newfdp->fd_cdir = fdp->fd_cdir; 1609 vref(newfdp->fd_cdir); 1610 cache_copy(&fdp->fd_ncdir, &newfdp->fd_ncdir); 1611 } 1612 1613 /* 1614 * rdir may not be set in e.g. proc0 or anything vm_fork'd off of 1615 * proc0, but should unconditionally exist in other processes. 1616 */ 1617 if (fdp->fd_rdir) { 1618 newfdp->fd_rdir = fdp->fd_rdir; 1619 vref(newfdp->fd_rdir); 1620 cache_copy(&fdp->fd_nrdir, &newfdp->fd_nrdir); 1621 } 1622 if (fdp->fd_jdir) { 1623 newfdp->fd_jdir = fdp->fd_jdir; 1624 vref(newfdp->fd_jdir); 1625 cache_copy(&fdp->fd_njdir, &newfdp->fd_njdir); 1626 } 1627 spin_unlock_rd(&fdp->fd_spin); 1628 1629 /* Create the file descriptor table. */ 1630 newfdp->fd_refcnt = 1; 1631 newfdp->fd_cmask = cmask; 1632 newfdp->fd_files = newfdp->fd_builtin_files; 1633 newfdp->fd_nfiles = NDFILE; 1634 newfdp->fd_knlistsize = -1; 1635 newfdp->fd_lastfile = -1; 1636 spin_init(&newfdp->fd_spin); 1637 1638 return (newfdp); 1639 } 1640 1641 /* 1642 * Share a filedesc structure. 1643 * 1644 * MPSAFE 1645 */ 1646 struct filedesc * 1647 fdshare(struct proc *p) 1648 { 1649 struct filedesc *fdp; 1650 1651 fdp = p->p_fd; 1652 spin_lock_wr(&fdp->fd_spin); 1653 fdp->fd_refcnt++; 1654 spin_unlock_wr(&fdp->fd_spin); 1655 return (fdp); 1656 } 1657 1658 /* 1659 * Copy a filedesc structure. 1660 * 1661 * MPSAFE 1662 */ 1663 struct filedesc * 1664 fdcopy(struct proc *p) 1665 { 1666 struct filedesc *fdp = p->p_fd; 1667 struct filedesc *newfdp; 1668 struct fdnode *fdnode; 1669 int i; 1670 int ni; 1671 1672 /* 1673 * Certain daemons might not have file descriptors. 1674 */ 1675 if (fdp == NULL) 1676 return (NULL); 1677 1678 /* 1679 * Allocate the new filedesc and fd_files[] array. This can race 1680 * with operations by other threads on the fdp so we have to be 1681 * careful. 1682 */ 1683 newfdp = kmalloc(sizeof(struct filedesc), M_FILEDESC, M_WAITOK | M_ZERO); 1684 again: 1685 spin_lock_rd(&fdp->fd_spin); 1686 if (fdp->fd_lastfile < NDFILE) { 1687 newfdp->fd_files = newfdp->fd_builtin_files; 1688 i = NDFILE; 1689 } else { 1690 /* 1691 * We have to allocate (N^2-1) entries for our in-place 1692 * binary tree. Allow the table to shrink. 1693 */ 1694 i = fdp->fd_nfiles; 1695 ni = (i - 1) / 2; 1696 while (ni > fdp->fd_lastfile && ni > NDFILE) { 1697 i = ni; 1698 ni = (i - 1) / 2; 1699 } 1700 spin_unlock_rd(&fdp->fd_spin); 1701 newfdp->fd_files = kmalloc(i * sizeof(struct fdnode), 1702 M_FILEDESC, M_WAITOK | M_ZERO); 1703 1704 /* 1705 * Check for race, retry 1706 */ 1707 spin_lock_rd(&fdp->fd_spin); 1708 if (i <= fdp->fd_lastfile) { 1709 spin_unlock_rd(&fdp->fd_spin); 1710 kfree(newfdp->fd_files, M_FILEDESC); 1711 goto again; 1712 } 1713 } 1714 1715 /* 1716 * Dup the remaining fields. vref() and cache_hold() can be 1717 * safely called while holding the read spinlock on fdp. 1718 * 1719 * The read spinlock on fdp is still being held. 1720 * 1721 * NOTE: vref and cache_hold calls for the case where the vnode 1722 * or cache entry already has at least one ref may be called 1723 * while holding spin locks. 1724 */ 1725 if ((newfdp->fd_cdir = fdp->fd_cdir) != NULL) { 1726 vref(newfdp->fd_cdir); 1727 cache_copy(&fdp->fd_ncdir, &newfdp->fd_ncdir); 1728 } 1729 /* 1730 * We must check for fd_rdir here, at least for now because 1731 * the init process is created before we have access to the 1732 * rootvode to take a reference to it. 1733 */ 1734 if ((newfdp->fd_rdir = fdp->fd_rdir) != NULL) { 1735 vref(newfdp->fd_rdir); 1736 cache_copy(&fdp->fd_nrdir, &newfdp->fd_nrdir); 1737 } 1738 if ((newfdp->fd_jdir = fdp->fd_jdir) != NULL) { 1739 vref(newfdp->fd_jdir); 1740 cache_copy(&fdp->fd_njdir, &newfdp->fd_njdir); 1741 } 1742 newfdp->fd_refcnt = 1; 1743 newfdp->fd_nfiles = i; 1744 newfdp->fd_lastfile = fdp->fd_lastfile; 1745 newfdp->fd_freefile = fdp->fd_freefile; 1746 newfdp->fd_cmask = fdp->fd_cmask; 1747 newfdp->fd_knlist = NULL; 1748 newfdp->fd_knlistsize = -1; 1749 newfdp->fd_knhash = NULL; 1750 newfdp->fd_knhashmask = 0; 1751 spin_init(&newfdp->fd_spin); 1752 1753 /* 1754 * Copy the descriptor table through (i). This also copies the 1755 * allocation state. Then go through and ref the file pointers 1756 * and clean up any KQ descriptors. 1757 * 1758 * kq descriptors cannot be copied. Since we haven't ref'd the 1759 * copied files yet we can ignore the return value from funsetfd(). 1760 * 1761 * The read spinlock on fdp is still being held. 1762 */ 1763 bcopy(fdp->fd_files, newfdp->fd_files, i * sizeof(struct fdnode)); 1764 for (i = 0 ; i < newfdp->fd_nfiles; ++i) { 1765 fdnode = &newfdp->fd_files[i]; 1766 if (fdnode->reserved) { 1767 fdreserve_locked(newfdp, i, -1); 1768 fdnode->reserved = 0; 1769 fdfixup_locked(newfdp, i); 1770 } else if (fdnode->fp) { 1771 if (fdnode->fp->f_type == DTYPE_KQUEUE) { 1772 (void)funsetfd_locked(newfdp, i); 1773 } else { 1774 fhold(fdnode->fp); 1775 } 1776 } 1777 } 1778 spin_unlock_rd(&fdp->fd_spin); 1779 return (newfdp); 1780 } 1781 1782 /* 1783 * Release a filedesc structure. 1784 * 1785 * NOT MPSAFE (MPSAFE for refs > 1, but the final cleanup code is not MPSAFE) 1786 */ 1787 void 1788 fdfree(struct proc *p) 1789 { 1790 struct filedesc *fdp = p->p_fd; 1791 struct fdnode *fdnode; 1792 int i; 1793 struct filedesc_to_leader *fdtol; 1794 struct file *fp; 1795 struct vnode *vp; 1796 struct flock lf; 1797 1798 /* Certain daemons might not have file descriptors. */ 1799 if (fdp == NULL) 1800 return; 1801 1802 /* 1803 * Severe messing around to follow 1804 */ 1805 spin_lock_wr(&fdp->fd_spin); 1806 1807 /* Check for special need to clear POSIX style locks */ 1808 fdtol = p->p_fdtol; 1809 if (fdtol != NULL) { 1810 KASSERT(fdtol->fdl_refcount > 0, 1811 ("filedesc_to_refcount botch: fdl_refcount=%d", 1812 fdtol->fdl_refcount)); 1813 if (fdtol->fdl_refcount == 1 && 1814 (p->p_leader->p_flag & P_ADVLOCK) != 0) { 1815 for (i = 0; i <= fdp->fd_lastfile; ++i) { 1816 fdnode = &fdp->fd_files[i]; 1817 if (fdnode->fp == NULL || 1818 fdnode->fp->f_type != DTYPE_VNODE) { 1819 continue; 1820 } 1821 fp = fdnode->fp; 1822 fhold(fp); 1823 spin_unlock_wr(&fdp->fd_spin); 1824 1825 lf.l_whence = SEEK_SET; 1826 lf.l_start = 0; 1827 lf.l_len = 0; 1828 lf.l_type = F_UNLCK; 1829 vp = (struct vnode *)fp->f_data; 1830 (void) VOP_ADVLOCK(vp, 1831 (caddr_t)p->p_leader, 1832 F_UNLCK, 1833 &lf, 1834 F_POSIX); 1835 fdrop(fp); 1836 spin_lock_wr(&fdp->fd_spin); 1837 } 1838 } 1839 retry: 1840 if (fdtol->fdl_refcount == 1) { 1841 if (fdp->fd_holdleaderscount > 0 && 1842 (p->p_leader->p_flag & P_ADVLOCK) != 0) { 1843 /* 1844 * close() or do_dup() has cleared a reference 1845 * in a shared file descriptor table. 1846 */ 1847 fdp->fd_holdleaderswakeup = 1; 1848 msleep(&fdp->fd_holdleaderscount, 1849 &fdp->fd_spin, 0, "fdlhold", 0); 1850 goto retry; 1851 } 1852 if (fdtol->fdl_holdcount > 0) { 1853 /* 1854 * Ensure that fdtol->fdl_leader 1855 * remains valid in closef(). 1856 */ 1857 fdtol->fdl_wakeup = 1; 1858 msleep(fdtol, &fdp->fd_spin, 0, "fdlhold", 0); 1859 goto retry; 1860 } 1861 } 1862 fdtol->fdl_refcount--; 1863 if (fdtol->fdl_refcount == 0 && 1864 fdtol->fdl_holdcount == 0) { 1865 fdtol->fdl_next->fdl_prev = fdtol->fdl_prev; 1866 fdtol->fdl_prev->fdl_next = fdtol->fdl_next; 1867 } else { 1868 fdtol = NULL; 1869 } 1870 p->p_fdtol = NULL; 1871 if (fdtol != NULL) { 1872 spin_unlock_wr(&fdp->fd_spin); 1873 kfree(fdtol, M_FILEDESC_TO_LEADER); 1874 spin_lock_wr(&fdp->fd_spin); 1875 } 1876 } 1877 if (--fdp->fd_refcnt > 0) { 1878 spin_unlock_wr(&fdp->fd_spin); 1879 return; 1880 } 1881 spin_unlock_wr(&fdp->fd_spin); 1882 1883 /* 1884 * we are the last reference to the structure, we can 1885 * safely assume it will not change out from under us. 1886 */ 1887 for (i = 0; i <= fdp->fd_lastfile; ++i) { 1888 if (fdp->fd_files[i].fp) 1889 closef(fdp->fd_files[i].fp, p); 1890 } 1891 if (fdp->fd_files != fdp->fd_builtin_files) 1892 kfree(fdp->fd_files, M_FILEDESC); 1893 if (fdp->fd_cdir) { 1894 cache_drop(&fdp->fd_ncdir); 1895 vrele(fdp->fd_cdir); 1896 } 1897 if (fdp->fd_rdir) { 1898 cache_drop(&fdp->fd_nrdir); 1899 vrele(fdp->fd_rdir); 1900 } 1901 if (fdp->fd_jdir) { 1902 cache_drop(&fdp->fd_njdir); 1903 vrele(fdp->fd_jdir); 1904 } 1905 if (fdp->fd_knlist) 1906 kfree(fdp->fd_knlist, M_KQUEUE); 1907 if (fdp->fd_knhash) 1908 kfree(fdp->fd_knhash, M_KQUEUE); 1909 kfree(fdp, M_FILEDESC); 1910 } 1911 1912 /* 1913 * Retrieve and reference the file pointer associated with a descriptor. 1914 * 1915 * MPSAFE 1916 */ 1917 struct file * 1918 holdfp(struct filedesc *fdp, int fd, int flag) 1919 { 1920 struct file* fp; 1921 1922 spin_lock_rd(&fdp->fd_spin); 1923 if (((u_int)fd) >= fdp->fd_nfiles) { 1924 fp = NULL; 1925 goto done; 1926 } 1927 if ((fp = fdp->fd_files[fd].fp) == NULL) 1928 goto done; 1929 if ((fp->f_flag & flag) == 0 && flag != -1) { 1930 fp = NULL; 1931 goto done; 1932 } 1933 fhold(fp); 1934 done: 1935 spin_unlock_rd(&fdp->fd_spin); 1936 return (fp); 1937 } 1938 1939 /* 1940 * holdsock() - load the struct file pointer associated 1941 * with a socket into *fpp. If an error occurs, non-zero 1942 * will be returned and *fpp will be set to NULL. 1943 * 1944 * MPSAFE 1945 */ 1946 int 1947 holdsock(struct filedesc *fdp, int fd, struct file **fpp) 1948 { 1949 struct file *fp; 1950 int error; 1951 1952 spin_lock_rd(&fdp->fd_spin); 1953 if ((unsigned)fd >= fdp->fd_nfiles) { 1954 error = EBADF; 1955 fp = NULL; 1956 goto done; 1957 } 1958 if ((fp = fdp->fd_files[fd].fp) == NULL) { 1959 error = EBADF; 1960 goto done; 1961 } 1962 if (fp->f_type != DTYPE_SOCKET) { 1963 error = ENOTSOCK; 1964 goto done; 1965 } 1966 fhold(fp); 1967 error = 0; 1968 done: 1969 spin_unlock_rd(&fdp->fd_spin); 1970 *fpp = fp; 1971 return (error); 1972 } 1973 1974 /* 1975 * Convert a user file descriptor to a held file pointer. 1976 * 1977 * MPSAFE 1978 */ 1979 int 1980 holdvnode(struct filedesc *fdp, int fd, struct file **fpp) 1981 { 1982 struct file *fp; 1983 int error; 1984 1985 spin_lock_rd(&fdp->fd_spin); 1986 if ((unsigned)fd >= fdp->fd_nfiles) { 1987 error = EBADF; 1988 fp = NULL; 1989 goto done; 1990 } 1991 if ((fp = fdp->fd_files[fd].fp) == NULL) { 1992 error = EBADF; 1993 goto done; 1994 } 1995 if (fp->f_type != DTYPE_VNODE && fp->f_type != DTYPE_FIFO) { 1996 fp = NULL; 1997 error = EINVAL; 1998 goto done; 1999 } 2000 fhold(fp); 2001 error = 0; 2002 done: 2003 spin_unlock_rd(&fdp->fd_spin); 2004 *fpp = fp; 2005 return (error); 2006 } 2007 2008 /* 2009 * For setugid programs, we don't want to people to use that setugidness 2010 * to generate error messages which write to a file which otherwise would 2011 * otherwise be off-limits to the process. 2012 * 2013 * This is a gross hack to plug the hole. A better solution would involve 2014 * a special vop or other form of generalized access control mechanism. We 2015 * go ahead and just reject all procfs file systems accesses as dangerous. 2016 * 2017 * Since setugidsafety calls this only for fd 0, 1 and 2, this check is 2018 * sufficient. We also don't for check setugidness since we know we are. 2019 */ 2020 static int 2021 is_unsafe(struct file *fp) 2022 { 2023 if (fp->f_type == DTYPE_VNODE && 2024 ((struct vnode *)(fp->f_data))->v_tag == VT_PROCFS) 2025 return (1); 2026 return (0); 2027 } 2028 2029 /* 2030 * Make this setguid thing safe, if at all possible. 2031 * 2032 * NOT MPSAFE - scans fdp without spinlocks, calls knote_fdclose() 2033 */ 2034 void 2035 setugidsafety(struct proc *p) 2036 { 2037 struct filedesc *fdp = p->p_fd; 2038 int i; 2039 2040 /* Certain daemons might not have file descriptors. */ 2041 if (fdp == NULL) 2042 return; 2043 2044 /* 2045 * note: fdp->fd_files may be reallocated out from under us while 2046 * we are blocked in a close. Be careful! 2047 */ 2048 for (i = 0; i <= fdp->fd_lastfile; i++) { 2049 if (i > 2) 2050 break; 2051 if (fdp->fd_files[i].fp && is_unsafe(fdp->fd_files[i].fp)) { 2052 struct file *fp; 2053 2054 if (i < fdp->fd_knlistsize) 2055 knote_fdclose(p, i); 2056 /* 2057 * NULL-out descriptor prior to close to avoid 2058 * a race while close blocks. 2059 */ 2060 if ((fp = funsetfd_locked(fdp, i)) != NULL) 2061 closef(fp, p); 2062 } 2063 } 2064 } 2065 2066 /* 2067 * Close any files on exec? 2068 * 2069 * NOT MPSAFE - scans fdp without spinlocks, calls knote_fdclose() 2070 */ 2071 void 2072 fdcloseexec(struct proc *p) 2073 { 2074 struct filedesc *fdp = p->p_fd; 2075 int i; 2076 2077 /* Certain daemons might not have file descriptors. */ 2078 if (fdp == NULL) 2079 return; 2080 2081 /* 2082 * We cannot cache fd_files since operations may block and rip 2083 * them out from under us. 2084 */ 2085 for (i = 0; i <= fdp->fd_lastfile; i++) { 2086 if (fdp->fd_files[i].fp != NULL && 2087 (fdp->fd_files[i].fileflags & UF_EXCLOSE)) { 2088 struct file *fp; 2089 2090 if (i < fdp->fd_knlistsize) 2091 knote_fdclose(p, i); 2092 /* 2093 * NULL-out descriptor prior to close to avoid 2094 * a race while close blocks. 2095 */ 2096 if ((fp = funsetfd_locked(fdp, i)) != NULL) 2097 closef(fp, p); 2098 } 2099 } 2100 } 2101 2102 /* 2103 * It is unsafe for set[ug]id processes to be started with file 2104 * descriptors 0..2 closed, as these descriptors are given implicit 2105 * significance in the Standard C library. fdcheckstd() will create a 2106 * descriptor referencing /dev/null for each of stdin, stdout, and 2107 * stderr that is not already open. 2108 * 2109 * NOT MPSAFE - calls falloc, vn_open, etc 2110 */ 2111 int 2112 fdcheckstd(struct proc *p) 2113 { 2114 struct nlookupdata nd; 2115 struct filedesc *fdp; 2116 struct file *fp; 2117 register_t retval; 2118 int i, error, flags, devnull; 2119 2120 fdp = p->p_fd; 2121 if (fdp == NULL) 2122 return (0); 2123 devnull = -1; 2124 error = 0; 2125 for (i = 0; i < 3; i++) { 2126 if (fdp->fd_files[i].fp != NULL) 2127 continue; 2128 if (devnull < 0) { 2129 if ((error = falloc(p, &fp, &devnull)) != 0) 2130 break; 2131 2132 error = nlookup_init(&nd, "/dev/null", UIO_SYSSPACE, 2133 NLC_FOLLOW|NLC_LOCKVP); 2134 flags = FREAD | FWRITE; 2135 if (error == 0) 2136 error = vn_open(&nd, fp, flags, 0); 2137 if (error == 0) 2138 fsetfd(p, fp, devnull); 2139 else 2140 fsetfd(p, NULL, devnull); 2141 fdrop(fp); 2142 nlookup_done(&nd); 2143 if (error) 2144 break; 2145 KKASSERT(i == devnull); 2146 } else { 2147 error = kern_dup(DUP_FIXED, devnull, i, &retval); 2148 if (error != 0) 2149 break; 2150 } 2151 } 2152 return (error); 2153 } 2154 2155 /* 2156 * Internal form of close. 2157 * Decrement reference count on file structure. 2158 * Note: td and/or p may be NULL when closing a file 2159 * that was being passed in a message. 2160 * 2161 * MPALMOSTSAFE - acquires mplock for VOP operations 2162 */ 2163 int 2164 closef(struct file *fp, struct proc *p) 2165 { 2166 struct vnode *vp; 2167 struct flock lf; 2168 struct filedesc_to_leader *fdtol; 2169 2170 if (fp == NULL) 2171 return (0); 2172 2173 /* 2174 * POSIX record locking dictates that any close releases ALL 2175 * locks owned by this process. This is handled by setting 2176 * a flag in the unlock to free ONLY locks obeying POSIX 2177 * semantics, and not to free BSD-style file locks. 2178 * If the descriptor was in a message, POSIX-style locks 2179 * aren't passed with the descriptor. 2180 */ 2181 if (p != NULL && fp->f_type == DTYPE_VNODE && 2182 (((struct vnode *)fp->f_data)->v_flag & VMAYHAVELOCKS) 2183 ) { 2184 get_mplock(); 2185 if ((p->p_leader->p_flag & P_ADVLOCK) != 0) { 2186 lf.l_whence = SEEK_SET; 2187 lf.l_start = 0; 2188 lf.l_len = 0; 2189 lf.l_type = F_UNLCK; 2190 vp = (struct vnode *)fp->f_data; 2191 (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK, 2192 &lf, F_POSIX); 2193 } 2194 fdtol = p->p_fdtol; 2195 if (fdtol != NULL) { 2196 /* 2197 * Handle special case where file descriptor table 2198 * is shared between multiple process leaders. 2199 */ 2200 for (fdtol = fdtol->fdl_next; 2201 fdtol != p->p_fdtol; 2202 fdtol = fdtol->fdl_next) { 2203 if ((fdtol->fdl_leader->p_flag & 2204 P_ADVLOCK) == 0) 2205 continue; 2206 fdtol->fdl_holdcount++; 2207 lf.l_whence = SEEK_SET; 2208 lf.l_start = 0; 2209 lf.l_len = 0; 2210 lf.l_type = F_UNLCK; 2211 vp = (struct vnode *)fp->f_data; 2212 (void) VOP_ADVLOCK(vp, 2213 (caddr_t)fdtol->fdl_leader, 2214 F_UNLCK, &lf, F_POSIX); 2215 fdtol->fdl_holdcount--; 2216 if (fdtol->fdl_holdcount == 0 && 2217 fdtol->fdl_wakeup != 0) { 2218 fdtol->fdl_wakeup = 0; 2219 wakeup(fdtol); 2220 } 2221 } 2222 } 2223 rel_mplock(); 2224 } 2225 return (fdrop(fp)); 2226 } 2227 2228 /* 2229 * MPSAFE 2230 * 2231 * fhold() can only be called if f_count is already at least 1 (i.e. the 2232 * caller of fhold() already has a reference to the file pointer in some 2233 * manner or other). 2234 * 2235 * f_count is not spin-locked. Instead, atomic ops are used for 2236 * incrementing, decrementing, and handling the 1->0 transition. 2237 */ 2238 void 2239 fhold(struct file *fp) 2240 { 2241 atomic_add_int(&fp->f_count, 1); 2242 } 2243 2244 /* 2245 * fdrop() - drop a reference to a descriptor 2246 * 2247 * MPALMOSTSAFE - acquires mplock for final close sequence 2248 */ 2249 int 2250 fdrop(struct file *fp) 2251 { 2252 struct flock lf; 2253 struct vnode *vp; 2254 int error; 2255 2256 /* 2257 * A combined fetch and subtract is needed to properly detect 2258 * 1->0 transitions, otherwise two cpus dropping from a ref 2259 * count of 2 might both try to run the 1->0 code. 2260 */ 2261 if (atomic_fetchadd_int(&fp->f_count, -1) > 1) 2262 return (0); 2263 2264 get_mplock(); 2265 2266 /* 2267 * The last reference has gone away, we own the fp structure free 2268 * and clear. 2269 */ 2270 if (fp->f_count < 0) 2271 panic("fdrop: count < 0"); 2272 if ((fp->f_flag & FHASLOCK) && fp->f_type == DTYPE_VNODE && 2273 (((struct vnode *)fp->f_data)->v_flag & VMAYHAVELOCKS) 2274 ) { 2275 lf.l_whence = SEEK_SET; 2276 lf.l_start = 0; 2277 lf.l_len = 0; 2278 lf.l_type = F_UNLCK; 2279 vp = (struct vnode *)fp->f_data; 2280 (void) VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, 0); 2281 } 2282 if (fp->f_ops != &badfileops) 2283 error = fo_close(fp); 2284 else 2285 error = 0; 2286 ffree(fp); 2287 rel_mplock(); 2288 return (error); 2289 } 2290 2291 /* 2292 * Apply an advisory lock on a file descriptor. 2293 * 2294 * Just attempt to get a record lock of the requested type on 2295 * the entire file (l_whence = SEEK_SET, l_start = 0, l_len = 0). 2296 */ 2297 int 2298 sys_flock(struct flock_args *uap) 2299 { 2300 struct proc *p = curproc; 2301 struct file *fp; 2302 struct vnode *vp; 2303 struct flock lf; 2304 int error; 2305 2306 if ((fp = holdfp(p->p_fd, uap->fd, -1)) == NULL) 2307 return (EBADF); 2308 if (fp->f_type != DTYPE_VNODE) { 2309 error = EOPNOTSUPP; 2310 goto done; 2311 } 2312 vp = (struct vnode *)fp->f_data; 2313 lf.l_whence = SEEK_SET; 2314 lf.l_start = 0; 2315 lf.l_len = 0; 2316 if (uap->how & LOCK_UN) { 2317 lf.l_type = F_UNLCK; 2318 fp->f_flag &= ~FHASLOCK; 2319 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, 0); 2320 goto done; 2321 } 2322 if (uap->how & LOCK_EX) 2323 lf.l_type = F_WRLCK; 2324 else if (uap->how & LOCK_SH) 2325 lf.l_type = F_RDLCK; 2326 else { 2327 error = EBADF; 2328 goto done; 2329 } 2330 fp->f_flag |= FHASLOCK; 2331 if (uap->how & LOCK_NB) 2332 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, 0); 2333 else 2334 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, F_WAIT); 2335 done: 2336 fdrop(fp); 2337 return (error); 2338 } 2339 2340 /* 2341 * File Descriptor pseudo-device driver (/dev/fd/). 2342 * 2343 * Opening minor device N dup()s the file (if any) connected to file 2344 * descriptor N belonging to the calling process. Note that this driver 2345 * consists of only the ``open()'' routine, because all subsequent 2346 * references to this file will be direct to the other driver. 2347 */ 2348 /* ARGSUSED */ 2349 static int 2350 fdopen(struct dev_open_args *ap) 2351 { 2352 thread_t td = curthread; 2353 2354 KKASSERT(td->td_lwp != NULL); 2355 2356 /* 2357 * XXX Kludge: set curlwp->lwp_dupfd to contain the value of the 2358 * the file descriptor being sought for duplication. The error 2359 * return ensures that the vnode for this device will be released 2360 * by vn_open. Open will detect this special error and take the 2361 * actions in dupfdopen below. Other callers of vn_open or VOP_OPEN 2362 * will simply report the error. 2363 */ 2364 td->td_lwp->lwp_dupfd = minor(ap->a_head.a_dev); 2365 return (ENODEV); 2366 } 2367 2368 /* 2369 * The caller has reserved the file descriptor dfd for us. On success we 2370 * must fsetfd() it. On failure the caller will clean it up. 2371 * 2372 * NOT MPSAFE - isn't getting spinlocks, possibly other things 2373 */ 2374 int 2375 dupfdopen(struct proc *p, int dfd, int sfd, int mode, int error) 2376 { 2377 struct filedesc *fdp = p->p_fd; 2378 struct file *wfp; 2379 struct file *xfp; 2380 int werror; 2381 2382 if ((wfp = holdfp(fdp, sfd, -1)) == NULL) 2383 return (EBADF); 2384 2385 /* 2386 * Close a revoke/dup race. Duping a descriptor marked as revoked 2387 * will dup a dummy descriptor instead of the real one. 2388 */ 2389 if (wfp->f_flag & FREVOKED) { 2390 kprintf("Warning: attempt to dup() a revoked descriptor\n"); 2391 fdrop(wfp); 2392 wfp = NULL; 2393 werror = falloc(NULL, &wfp, NULL); 2394 if (werror) 2395 return (werror); 2396 } 2397 2398 /* 2399 * There are two cases of interest here. 2400 * 2401 * For ENODEV simply dup sfd to file descriptor dfd and return. 2402 * 2403 * For ENXIO steal away the file structure from sfd and store it 2404 * dfd. sfd is effectively closed by this operation. 2405 * 2406 * Any other error code is just returned. 2407 */ 2408 switch (error) { 2409 case ENODEV: 2410 /* 2411 * Check that the mode the file is being opened for is a 2412 * subset of the mode of the existing descriptor. 2413 */ 2414 if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag) { 2415 error = EACCES; 2416 break; 2417 } 2418 fdp->fd_files[dfd].fileflags = fdp->fd_files[sfd].fileflags; 2419 fsetfd(p, wfp, dfd); 2420 error = 0; 2421 break; 2422 case ENXIO: 2423 /* 2424 * Steal away the file pointer from dfd, and stuff it into indx. 2425 */ 2426 fdp->fd_files[dfd].fileflags = fdp->fd_files[sfd].fileflags; 2427 fsetfd(p, wfp, dfd); 2428 if ((xfp = funsetfd_locked(fdp, sfd)) != NULL) 2429 fdrop(xfp); 2430 error = 0; 2431 break; 2432 default: 2433 break; 2434 } 2435 fdrop(wfp); 2436 return (error); 2437 } 2438 2439 /* 2440 * NOT MPSAFE - I think these refer to a common file descriptor table 2441 * and we need to spinlock that to link fdtol in. 2442 */ 2443 struct filedesc_to_leader * 2444 filedesc_to_leader_alloc(struct filedesc_to_leader *old, 2445 struct proc *leader) 2446 { 2447 struct filedesc_to_leader *fdtol; 2448 2449 fdtol = kmalloc(sizeof(struct filedesc_to_leader), 2450 M_FILEDESC_TO_LEADER, M_WAITOK); 2451 fdtol->fdl_refcount = 1; 2452 fdtol->fdl_holdcount = 0; 2453 fdtol->fdl_wakeup = 0; 2454 fdtol->fdl_leader = leader; 2455 if (old != NULL) { 2456 fdtol->fdl_next = old->fdl_next; 2457 fdtol->fdl_prev = old; 2458 old->fdl_next = fdtol; 2459 fdtol->fdl_next->fdl_prev = fdtol; 2460 } else { 2461 fdtol->fdl_next = fdtol; 2462 fdtol->fdl_prev = fdtol; 2463 } 2464 return fdtol; 2465 } 2466 2467 /* 2468 * Scan all file pointers in the system. The callback is made with 2469 * the master list spinlock held exclusively. 2470 * 2471 * MPSAFE 2472 */ 2473 void 2474 allfiles_scan_exclusive(int (*callback)(struct file *, void *), void *data) 2475 { 2476 struct file *fp; 2477 int res; 2478 2479 spin_lock_wr(&filehead_spin); 2480 LIST_FOREACH(fp, &filehead, f_list) { 2481 res = callback(fp, data); 2482 if (res < 0) 2483 break; 2484 } 2485 spin_unlock_wr(&filehead_spin); 2486 } 2487 2488 /* 2489 * Get file structures. 2490 * 2491 * NOT MPSAFE - process list scan, SYSCTL_OUT (probably not mpsafe) 2492 */ 2493 2494 struct sysctl_kern_file_info { 2495 int count; 2496 int error; 2497 struct sysctl_req *req; 2498 }; 2499 2500 static int sysctl_kern_file_callback(struct proc *p, void *data); 2501 2502 static int 2503 sysctl_kern_file(SYSCTL_HANDLER_ARGS) 2504 { 2505 struct sysctl_kern_file_info info; 2506 2507 /* 2508 * Note: because the number of file descriptors is calculated 2509 * in different ways for sizing vs returning the data, 2510 * there is information leakage from the first loop. However, 2511 * it is of a similar order of magnitude to the leakage from 2512 * global system statistics such as kern.openfiles. 2513 * 2514 * When just doing a count, note that we cannot just count 2515 * the elements and add f_count via the filehead list because 2516 * threaded processes share their descriptor table and f_count might 2517 * still be '1' in that case. 2518 * 2519 * Since the SYSCTL op can block, we must hold the process to 2520 * prevent it being ripped out from under us either in the 2521 * file descriptor loop or in the greater LIST_FOREACH. The 2522 * process may be in varying states of disrepair. If the process 2523 * is in SZOMB we may have caught it just as it is being removed 2524 * from the allproc list, we must skip it in that case to maintain 2525 * an unbroken chain through the allproc list. 2526 */ 2527 info.count = 0; 2528 info.error = 0; 2529 info.req = req; 2530 allproc_scan(sysctl_kern_file_callback, &info); 2531 2532 /* 2533 * When just calculating the size, overestimate a bit to try to 2534 * prevent system activity from causing the buffer-fill call 2535 * to fail later on. 2536 */ 2537 if (req->oldptr == NULL) { 2538 info.count = (info.count + 16) + (info.count / 10); 2539 info.error = SYSCTL_OUT(req, NULL, 2540 info.count * sizeof(struct kinfo_file)); 2541 } 2542 return (info.error); 2543 } 2544 2545 static int 2546 sysctl_kern_file_callback(struct proc *p, void *data) 2547 { 2548 struct sysctl_kern_file_info *info = data; 2549 struct kinfo_file kf; 2550 struct filedesc *fdp; 2551 struct file *fp; 2552 uid_t uid; 2553 int n; 2554 2555 if (p->p_stat == SIDL || p->p_stat == SZOMB) 2556 return(0); 2557 if (!PRISON_CHECK(info->req->td->td_proc->p_ucred, p->p_ucred) != 0) 2558 return(0); 2559 if ((fdp = p->p_fd) == NULL) 2560 return(0); 2561 spin_lock_rd(&fdp->fd_spin); 2562 for (n = 0; n < fdp->fd_nfiles; ++n) { 2563 if ((fp = fdp->fd_files[n].fp) == NULL) 2564 continue; 2565 if (info->req->oldptr == NULL) { 2566 ++info->count; 2567 } else { 2568 uid = p->p_ucred ? p->p_ucred->cr_uid : -1; 2569 kcore_make_file(&kf, fp, p->p_pid, uid, n); 2570 spin_unlock_rd(&fdp->fd_spin); 2571 info->error = SYSCTL_OUT(info->req, &kf, sizeof(kf)); 2572 spin_lock_rd(&fdp->fd_spin); 2573 if (info->error) 2574 break; 2575 } 2576 } 2577 spin_unlock_rd(&fdp->fd_spin); 2578 if (info->error) 2579 return(-1); 2580 return(0); 2581 } 2582 2583 SYSCTL_PROC(_kern, KERN_FILE, file, CTLTYPE_OPAQUE|CTLFLAG_RD, 2584 0, 0, sysctl_kern_file, "S,file", "Entire file table"); 2585 2586 SYSCTL_INT(_kern, KERN_MAXFILESPERPROC, maxfilesperproc, CTLFLAG_RW, 2587 &maxfilesperproc, 0, "Maximum files allowed open per process"); 2588 2589 SYSCTL_INT(_kern, KERN_MAXFILES, maxfiles, CTLFLAG_RW, 2590 &maxfiles, 0, "Maximum number of files"); 2591 2592 SYSCTL_INT(_kern, OID_AUTO, maxfilesrootres, CTLFLAG_RW, 2593 &maxfilesrootres, 0, "Descriptors reserved for root use"); 2594 2595 SYSCTL_INT(_kern, OID_AUTO, openfiles, CTLFLAG_RD, 2596 &nfiles, 0, "System-wide number of open files"); 2597 2598 static void 2599 fildesc_drvinit(void *unused) 2600 { 2601 int fd; 2602 2603 dev_ops_add(&fildesc_ops, 0, 0); 2604 for (fd = 0; fd < NUMFDESC; fd++) { 2605 make_dev(&fildesc_ops, fd, 2606 UID_BIN, GID_BIN, 0666, "fd/%d", fd); 2607 } 2608 make_dev(&fildesc_ops, 0, UID_ROOT, GID_WHEEL, 0666, "stdin"); 2609 make_dev(&fildesc_ops, 1, UID_ROOT, GID_WHEEL, 0666, "stdout"); 2610 make_dev(&fildesc_ops, 2, UID_ROOT, GID_WHEEL, 0666, "stderr"); 2611 } 2612 2613 /* 2614 * MPSAFE 2615 */ 2616 struct fileops badfileops = { 2617 .fo_read = badfo_readwrite, 2618 .fo_write = badfo_readwrite, 2619 .fo_ioctl = badfo_ioctl, 2620 .fo_poll = badfo_poll, 2621 .fo_kqfilter = badfo_kqfilter, 2622 .fo_stat = badfo_stat, 2623 .fo_close = badfo_close, 2624 .fo_shutdown = badfo_shutdown 2625 }; 2626 2627 /* 2628 * MPSAFE 2629 */ 2630 static int 2631 badfo_readwrite( 2632 struct file *fp, 2633 struct uio *uio, 2634 struct ucred *cred, 2635 int flags 2636 ) { 2637 return (EBADF); 2638 } 2639 2640 /* 2641 * MPSAFE 2642 */ 2643 static int 2644 badfo_ioctl(struct file *fp, u_long com, caddr_t data, struct ucred *cred) 2645 { 2646 return (EBADF); 2647 } 2648 2649 /* 2650 * MPSAFE 2651 */ 2652 static int 2653 badfo_poll(struct file *fp, int events, struct ucred *cred) 2654 { 2655 return (0); 2656 } 2657 2658 /* 2659 * MPSAFE 2660 */ 2661 static int 2662 badfo_kqfilter(struct file *fp, struct knote *kn) 2663 { 2664 return (0); 2665 } 2666 2667 static int 2668 badfo_stat(struct file *fp, struct stat *sb, struct ucred *cred) 2669 { 2670 return (EBADF); 2671 } 2672 2673 /* 2674 * MPSAFE 2675 */ 2676 static int 2677 badfo_close(struct file *fp) 2678 { 2679 return (EBADF); 2680 } 2681 2682 /* 2683 * MPSAFE 2684 */ 2685 static int 2686 badfo_shutdown(struct file *fp, int how) 2687 { 2688 return (EBADF); 2689 } 2690 2691 /* 2692 * MPSAFE 2693 */ 2694 int 2695 nofo_shutdown(struct file *fp, int how) 2696 { 2697 return (EOPNOTSUPP); 2698 } 2699 2700 SYSINIT(fildescdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR, 2701 fildesc_drvinit,NULL) 2702