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