Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_descrip.c
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1 /*- 2 * Copyright (c) 1982, 1986, 1989, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 4. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)kern_descrip.c 8.6 (Berkeley) 4/19/94 35 */ 36 37 #include <sys/cdefs.h> 38 __FBSDID("$FreeBSD: releng/6.0/sys/kern/kern_descrip.c 151168 2005-10-09 08:13:56Z rik $"); 39 40 #include "opt_compat.h" 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 45 #include <sys/conf.h> 46 #include <sys/fcntl.h> 47 #include <sys/file.h> 48 #include <sys/filedesc.h> 49 #include <sys/filio.h> 50 #include <sys/jail.h> 51 #include <sys/kernel.h> 52 #include <sys/limits.h> 53 #include <sys/lock.h> 54 #include <sys/malloc.h> 55 #include <sys/mount.h> 56 #include <sys/mutex.h> 57 #include <sys/namei.h> 58 #include <sys/proc.h> 59 #include <sys/resourcevar.h> 60 #include <sys/signalvar.h> 61 #include <sys/socketvar.h> 62 #include <sys/stat.h> 63 #include <sys/sx.h> 64 #include <sys/syscallsubr.h> 65 #include <sys/sysctl.h> 66 #include <sys/sysproto.h> 67 #include <sys/unistd.h> 68 #include <sys/vnode.h> 69 70 #include <vm/uma.h> 71 72 static MALLOC_DEFINE(M_FILEDESC, "file desc", "Open file descriptor table"); 73 static MALLOC_DEFINE(M_FILEDESC_TO_LEADER, "file desc to leader", 74 "file desc to leader structures"); 75 static MALLOC_DEFINE(M_SIGIO, "sigio", "sigio structures"); 76 77 static uma_zone_t file_zone; 78 79 80 /* How to treat 'new' parameter when allocating a fd for do_dup(). */ 81 enum dup_type { DUP_VARIABLE, DUP_FIXED }; 82 83 static int do_dup(struct thread *td, enum dup_type type, int old, int new, 84 register_t *retval); 85 static int fd_first_free(struct filedesc *, int, int); 86 static int fd_last_used(struct filedesc *, int, int); 87 static void fdgrowtable(struct filedesc *, int); 88 static int fdrop_locked(struct file *fp, struct thread *td); 89 static void fdunused(struct filedesc *fdp, int fd); 90 static void fdused(struct filedesc *fdp, int fd); 91 92 /* 93 * A process is initially started out with NDFILE descriptors stored within 94 * this structure, selected to be enough for typical applications based on 95 * the historical limit of 20 open files (and the usage of descriptors by 96 * shells). If these descriptors are exhausted, a larger descriptor table 97 * may be allocated, up to a process' resource limit; the internal arrays 98 * are then unused. 99 */ 100 #define NDFILE 20 101 #define NDSLOTSIZE sizeof(NDSLOTTYPE) 102 #define NDENTRIES (NDSLOTSIZE * __CHAR_BIT) 103 #define NDSLOT(x) ((x) / NDENTRIES) 104 #define NDBIT(x) ((NDSLOTTYPE)1 << ((x) % NDENTRIES)) 105 #define NDSLOTS(x) (((x) + NDENTRIES - 1) / NDENTRIES) 106 107 /* 108 * Storage required per open file descriptor. 109 */ 110 #define OFILESIZE (sizeof(struct file *) + sizeof(char)) 111 112 /* 113 * Basic allocation of descriptors: 114 * one of the above, plus arrays for NDFILE descriptors. 115 */ 116 struct filedesc0 { 117 struct filedesc fd_fd; 118 /* 119 * These arrays are used when the number of open files is 120 * <= NDFILE, and are then pointed to by the pointers above. 121 */ 122 struct file *fd_dfiles[NDFILE]; 123 char fd_dfileflags[NDFILE]; 124 NDSLOTTYPE fd_dmap[NDSLOTS(NDFILE)]; 125 }; 126 127 /* 128 * Descriptor management. 129 */ 130 struct filelist filehead; /* head of list of open files */ 131 int openfiles; /* actual number of open files */ 132 struct sx filelist_lock; /* sx to protect filelist */ 133 struct mtx sigio_lock; /* mtx to protect pointers to sigio */ 134 135 /* A mutex to protect the association between a proc and filedesc. */ 136 static struct mtx fdesc_mtx; 137 138 /* 139 * Find the first zero bit in the given bitmap, starting at low and not 140 * exceeding size - 1. 141 */ 142 static int 143 fd_first_free(struct filedesc *fdp, int low, int size) 144 { 145 NDSLOTTYPE *map = fdp->fd_map; 146 NDSLOTTYPE mask; 147 int off, maxoff; 148 149 if (low >= size) 150 return (low); 151 152 off = NDSLOT(low); 153 if (low % NDENTRIES) { 154 mask = ~(~(NDSLOTTYPE)0 >> (NDENTRIES - (low % NDENTRIES))); 155 if ((mask &= ~map[off]) != 0UL) 156 return (off * NDENTRIES + ffsl(mask) - 1); 157 ++off; 158 } 159 for (maxoff = NDSLOTS(size); off < maxoff; ++off) 160 if (map[off] != ~0UL) 161 return (off * NDENTRIES + ffsl(~map[off]) - 1); 162 return (size); 163 } 164 165 /* 166 * Find the highest non-zero bit in the given bitmap, starting at low and 167 * not exceeding size - 1. 168 */ 169 static int 170 fd_last_used(struct filedesc *fdp, int low, int size) 171 { 172 NDSLOTTYPE *map = fdp->fd_map; 173 NDSLOTTYPE mask; 174 int off, minoff; 175 176 if (low >= size) 177 return (-1); 178 179 off = NDSLOT(size); 180 if (size % NDENTRIES) { 181 mask = ~(~(NDSLOTTYPE)0 << (size % NDENTRIES)); 182 if ((mask &= map[off]) != 0) 183 return (off * NDENTRIES + flsl(mask) - 1); 184 --off; 185 } 186 for (minoff = NDSLOT(low); off >= minoff; --off) 187 if (map[off] != 0) 188 return (off * NDENTRIES + flsl(map[off]) - 1); 189 return (size - 1); 190 } 191 192 static int 193 fdisused(struct filedesc *fdp, int fd) 194 { 195 KASSERT(fd >= 0 && fd < fdp->fd_nfiles, 196 ("file descriptor %d out of range (0, %d)", fd, fdp->fd_nfiles)); 197 return ((fdp->fd_map[NDSLOT(fd)] & NDBIT(fd)) != 0); 198 } 199 200 /* 201 * Mark a file descriptor as used. 202 */ 203 static void 204 fdused(struct filedesc *fdp, int fd) 205 { 206 FILEDESC_LOCK_ASSERT(fdp, MA_OWNED); 207 KASSERT(!fdisused(fdp, fd), 208 ("fd already used")); 209 fdp->fd_map[NDSLOT(fd)] |= NDBIT(fd); 210 if (fd > fdp->fd_lastfile) 211 fdp->fd_lastfile = fd; 212 if (fd == fdp->fd_freefile) 213 fdp->fd_freefile = fd_first_free(fdp, fd, fdp->fd_nfiles); 214 } 215 216 /* 217 * Mark a file descriptor as unused. 218 */ 219 static void 220 fdunused(struct filedesc *fdp, int fd) 221 { 222 FILEDESC_LOCK_ASSERT(fdp, MA_OWNED); 223 KASSERT(fdisused(fdp, fd), 224 ("fd is already unused")); 225 KASSERT(fdp->fd_ofiles[fd] == NULL, 226 ("fd is still in use")); 227 fdp->fd_map[NDSLOT(fd)] &= ~NDBIT(fd); 228 if (fd < fdp->fd_freefile) 229 fdp->fd_freefile = fd; 230 if (fd == fdp->fd_lastfile) 231 fdp->fd_lastfile = fd_last_used(fdp, 0, fd); 232 } 233 234 /* 235 * System calls on descriptors. 236 */ 237 #ifndef _SYS_SYSPROTO_H_ 238 struct getdtablesize_args { 239 int dummy; 240 }; 241 #endif 242 /* 243 * MPSAFE 244 */ 245 /* ARGSUSED */ 246 int 247 getdtablesize(struct thread *td, struct getdtablesize_args *uap) 248 { 249 struct proc *p = td->td_proc; 250 251 PROC_LOCK(p); 252 td->td_retval[0] = 253 min((int)lim_cur(p, RLIMIT_NOFILE), maxfilesperproc); 254 PROC_UNLOCK(p); 255 return (0); 256 } 257 258 /* 259 * Duplicate a file descriptor to a particular value. 260 * 261 * note: keep in mind that a potential race condition exists when closing 262 * descriptors from a shared descriptor table (via rfork). 263 */ 264 #ifndef _SYS_SYSPROTO_H_ 265 struct dup2_args { 266 u_int from; 267 u_int to; 268 }; 269 #endif 270 /* 271 * MPSAFE 272 */ 273 /* ARGSUSED */ 274 int 275 dup2(struct thread *td, struct dup2_args *uap) 276 { 277 278 return (do_dup(td, DUP_FIXED, (int)uap->from, (int)uap->to, 279 td->td_retval)); 280 } 281 282 /* 283 * Duplicate a file descriptor. 284 */ 285 #ifndef _SYS_SYSPROTO_H_ 286 struct dup_args { 287 u_int fd; 288 }; 289 #endif 290 /* 291 * MPSAFE 292 */ 293 /* ARGSUSED */ 294 int 295 dup(struct thread *td, struct dup_args *uap) 296 { 297 298 return (do_dup(td, DUP_VARIABLE, (int)uap->fd, 0, td->td_retval)); 299 } 300 301 /* 302 * The file control system call. 303 */ 304 #ifndef _SYS_SYSPROTO_H_ 305 struct fcntl_args { 306 int fd; 307 int cmd; 308 long arg; 309 }; 310 #endif 311 /* 312 * MPSAFE 313 */ 314 /* ARGSUSED */ 315 int 316 fcntl(struct thread *td, struct fcntl_args *uap) 317 { 318 struct flock fl; 319 intptr_t arg; 320 int error; 321 322 error = 0; 323 switch (uap->cmd) { 324 case F_GETLK: 325 case F_SETLK: 326 case F_SETLKW: 327 error = copyin((void *)(intptr_t)uap->arg, &fl, sizeof(fl)); 328 arg = (intptr_t)&fl; 329 break; 330 default: 331 arg = uap->arg; 332 break; 333 } 334 if (error) 335 return (error); 336 error = kern_fcntl(td, uap->fd, uap->cmd, arg); 337 if (error) 338 return (error); 339 if (uap->cmd == F_GETLK) 340 error = copyout(&fl, (void *)(intptr_t)uap->arg, sizeof(fl)); 341 return (error); 342 } 343 344 int 345 kern_fcntl(struct thread *td, int fd, int cmd, intptr_t arg) 346 { 347 struct filedesc *fdp; 348 struct flock *flp; 349 struct file *fp; 350 struct proc *p; 351 char *pop; 352 struct vnode *vp; 353 u_int newmin; 354 int error, flg, tmp; 355 int giant_locked; 356 357 /* 358 * XXXRW: Some fcntl() calls require Giant -- others don't. Try to 359 * avoid grabbing Giant for calls we know don't need it. 360 */ 361 switch (cmd) { 362 case F_DUPFD: 363 case F_GETFD: 364 case F_SETFD: 365 case F_GETFL: 366 giant_locked = 0; 367 break; 368 369 default: 370 giant_locked = 1; 371 mtx_lock(&Giant); 372 } 373 374 error = 0; 375 flg = F_POSIX; 376 p = td->td_proc; 377 fdp = p->p_fd; 378 FILEDESC_LOCK(fdp); 379 if ((unsigned)fd >= fdp->fd_nfiles || 380 (fp = fdp->fd_ofiles[fd]) == NULL) { 381 FILEDESC_UNLOCK(fdp); 382 error = EBADF; 383 goto done2; 384 } 385 pop = &fdp->fd_ofileflags[fd]; 386 387 switch (cmd) { 388 case F_DUPFD: 389 /* mtx_assert(&Giant, MA_NOTOWNED); */ 390 FILEDESC_UNLOCK(fdp); 391 newmin = arg; 392 PROC_LOCK(p); 393 if (newmin >= lim_cur(p, RLIMIT_NOFILE) || 394 newmin >= maxfilesperproc) { 395 PROC_UNLOCK(p); 396 error = EINVAL; 397 break; 398 } 399 PROC_UNLOCK(p); 400 error = do_dup(td, DUP_VARIABLE, fd, newmin, td->td_retval); 401 break; 402 403 case F_GETFD: 404 /* mtx_assert(&Giant, MA_NOTOWNED); */ 405 td->td_retval[0] = (*pop & UF_EXCLOSE) ? FD_CLOEXEC : 0; 406 FILEDESC_UNLOCK(fdp); 407 break; 408 409 case F_SETFD: 410 /* mtx_assert(&Giant, MA_NOTOWNED); */ 411 *pop = (*pop &~ UF_EXCLOSE) | 412 (arg & FD_CLOEXEC ? UF_EXCLOSE : 0); 413 FILEDESC_UNLOCK(fdp); 414 break; 415 416 case F_GETFL: 417 /* mtx_assert(&Giant, MA_NOTOWNED); */ 418 FILE_LOCK(fp); 419 td->td_retval[0] = OFLAGS(fp->f_flag); 420 FILE_UNLOCK(fp); 421 FILEDESC_UNLOCK(fdp); 422 break; 423 424 case F_SETFL: 425 mtx_assert(&Giant, MA_OWNED); 426 FILE_LOCK(fp); 427 fhold_locked(fp); 428 fp->f_flag &= ~FCNTLFLAGS; 429 fp->f_flag |= FFLAGS(arg & ~O_ACCMODE) & FCNTLFLAGS; 430 FILE_UNLOCK(fp); 431 FILEDESC_UNLOCK(fdp); 432 tmp = fp->f_flag & FNONBLOCK; 433 error = fo_ioctl(fp, FIONBIO, &tmp, td->td_ucred, td); 434 if (error) { 435 fdrop(fp, td); 436 break; 437 } 438 tmp = fp->f_flag & FASYNC; 439 error = fo_ioctl(fp, FIOASYNC, &tmp, td->td_ucred, td); 440 if (error == 0) { 441 fdrop(fp, td); 442 break; 443 } 444 FILE_LOCK(fp); 445 fp->f_flag &= ~FNONBLOCK; 446 FILE_UNLOCK(fp); 447 tmp = 0; 448 (void)fo_ioctl(fp, FIONBIO, &tmp, td->td_ucred, td); 449 fdrop(fp, td); 450 break; 451 452 case F_GETOWN: 453 mtx_assert(&Giant, MA_OWNED); 454 fhold(fp); 455 FILEDESC_UNLOCK(fdp); 456 error = fo_ioctl(fp, FIOGETOWN, &tmp, td->td_ucred, td); 457 if (error == 0) 458 td->td_retval[0] = tmp; 459 fdrop(fp, td); 460 break; 461 462 case F_SETOWN: 463 mtx_assert(&Giant, MA_OWNED); 464 fhold(fp); 465 FILEDESC_UNLOCK(fdp); 466 tmp = arg; 467 error = fo_ioctl(fp, FIOSETOWN, &tmp, td->td_ucred, td); 468 fdrop(fp, td); 469 break; 470 471 case F_SETLKW: 472 mtx_assert(&Giant, MA_OWNED); 473 flg |= F_WAIT; 474 /* FALLTHROUGH F_SETLK */ 475 476 case F_SETLK: 477 mtx_assert(&Giant, MA_OWNED); 478 if (fp->f_type != DTYPE_VNODE) { 479 FILEDESC_UNLOCK(fdp); 480 error = EBADF; 481 break; 482 } 483 484 flp = (struct flock *)arg; 485 if (flp->l_whence == SEEK_CUR) { 486 if (fp->f_offset < 0 || 487 (flp->l_start > 0 && 488 fp->f_offset > OFF_MAX - flp->l_start)) { 489 FILEDESC_UNLOCK(fdp); 490 error = EOVERFLOW; 491 break; 492 } 493 flp->l_start += fp->f_offset; 494 } 495 496 /* 497 * VOP_ADVLOCK() may block. 498 */ 499 fhold(fp); 500 FILEDESC_UNLOCK(fdp); 501 vp = fp->f_vnode; 502 503 switch (flp->l_type) { 504 case F_RDLCK: 505 if ((fp->f_flag & FREAD) == 0) { 506 error = EBADF; 507 break; 508 } 509 PROC_LOCK(p->p_leader); 510 p->p_leader->p_flag |= P_ADVLOCK; 511 PROC_UNLOCK(p->p_leader); 512 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK, 513 flp, flg); 514 break; 515 case F_WRLCK: 516 if ((fp->f_flag & FWRITE) == 0) { 517 error = EBADF; 518 break; 519 } 520 PROC_LOCK(p->p_leader); 521 p->p_leader->p_flag |= P_ADVLOCK; 522 PROC_UNLOCK(p->p_leader); 523 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK, 524 flp, flg); 525 break; 526 case F_UNLCK: 527 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK, 528 flp, F_POSIX); 529 break; 530 default: 531 error = EINVAL; 532 break; 533 } 534 /* Check for race with close */ 535 FILEDESC_LOCK_FAST(fdp); 536 if ((unsigned) fd >= fdp->fd_nfiles || 537 fp != fdp->fd_ofiles[fd]) { 538 FILEDESC_UNLOCK_FAST(fdp); 539 flp->l_whence = SEEK_SET; 540 flp->l_start = 0; 541 flp->l_len = 0; 542 flp->l_type = F_UNLCK; 543 (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader, 544 F_UNLCK, flp, F_POSIX); 545 } else 546 FILEDESC_UNLOCK_FAST(fdp); 547 fdrop(fp, td); 548 break; 549 550 case F_GETLK: 551 mtx_assert(&Giant, MA_OWNED); 552 if (fp->f_type != DTYPE_VNODE) { 553 FILEDESC_UNLOCK(fdp); 554 error = EBADF; 555 break; 556 } 557 flp = (struct flock *)arg; 558 if (flp->l_type != F_RDLCK && flp->l_type != F_WRLCK && 559 flp->l_type != F_UNLCK) { 560 FILEDESC_UNLOCK(fdp); 561 error = EINVAL; 562 break; 563 } 564 if (flp->l_whence == SEEK_CUR) { 565 if ((flp->l_start > 0 && 566 fp->f_offset > OFF_MAX - flp->l_start) || 567 (flp->l_start < 0 && 568 fp->f_offset < OFF_MIN - flp->l_start)) { 569 FILEDESC_UNLOCK(fdp); 570 error = EOVERFLOW; 571 break; 572 } 573 flp->l_start += fp->f_offset; 574 } 575 /* 576 * VOP_ADVLOCK() may block. 577 */ 578 fhold(fp); 579 FILEDESC_UNLOCK(fdp); 580 vp = fp->f_vnode; 581 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_GETLK, flp, 582 F_POSIX); 583 fdrop(fp, td); 584 break; 585 default: 586 FILEDESC_UNLOCK(fdp); 587 error = EINVAL; 588 break; 589 } 590 done2: 591 if (giant_locked) 592 mtx_unlock(&Giant); 593 return (error); 594 } 595 596 /* 597 * Common code for dup, dup2, and fcntl(F_DUPFD). 598 */ 599 static int 600 do_dup(struct thread *td, enum dup_type type, int old, int new, register_t *retval) 601 { 602 struct filedesc *fdp; 603 struct proc *p; 604 struct file *fp; 605 struct file *delfp; 606 int error, holdleaders, maxfd; 607 608 KASSERT((type == DUP_VARIABLE || type == DUP_FIXED), 609 ("invalid dup type %d", type)); 610 611 p = td->td_proc; 612 fdp = p->p_fd; 613 614 /* 615 * Verify we have a valid descriptor to dup from and possibly to 616 * dup to. 617 */ 618 if (old < 0 || new < 0) 619 return (EBADF); 620 PROC_LOCK(p); 621 maxfd = min((int)lim_cur(p, RLIMIT_NOFILE), maxfilesperproc); 622 PROC_UNLOCK(p); 623 if (new >= maxfd) 624 return (EMFILE); 625 626 FILEDESC_LOCK(fdp); 627 if (old >= fdp->fd_nfiles || fdp->fd_ofiles[old] == NULL) { 628 FILEDESC_UNLOCK(fdp); 629 return (EBADF); 630 } 631 if (type == DUP_FIXED && old == new) { 632 *retval = new; 633 FILEDESC_UNLOCK(fdp); 634 return (0); 635 } 636 fp = fdp->fd_ofiles[old]; 637 fhold(fp); 638 639 /* 640 * If the caller specified a file descriptor, make sure the file 641 * table is large enough to hold it, and grab it. Otherwise, just 642 * allocate a new descriptor the usual way. Since the filedesc 643 * lock may be temporarily dropped in the process, we have to look 644 * out for a race. 645 */ 646 if (type == DUP_FIXED) { 647 if (new >= fdp->fd_nfiles) 648 fdgrowtable(fdp, new + 1); 649 if (fdp->fd_ofiles[new] == NULL) 650 fdused(fdp, new); 651 } else { 652 if ((error = fdalloc(td, new, &new)) != 0) { 653 FILEDESC_UNLOCK(fdp); 654 fdrop(fp, td); 655 return (error); 656 } 657 } 658 659 /* 660 * If the old file changed out from under us then treat it as a 661 * bad file descriptor. Userland should do its own locking to 662 * avoid this case. 663 */ 664 if (fdp->fd_ofiles[old] != fp) { 665 /* we've allocated a descriptor which we won't use */ 666 if (fdp->fd_ofiles[new] == NULL) 667 fdunused(fdp, new); 668 FILEDESC_UNLOCK(fdp); 669 fdrop(fp, td); 670 return (EBADF); 671 } 672 KASSERT(old != new, 673 ("new fd is same as old")); 674 675 /* 676 * Save info on the descriptor being overwritten. We cannot close 677 * it without introducing an ownership race for the slot, since we 678 * need to drop the filedesc lock to call closef(). 679 * 680 * XXX this duplicates parts of close(). 681 */ 682 delfp = fdp->fd_ofiles[new]; 683 holdleaders = 0; 684 if (delfp != NULL) { 685 if (td->td_proc->p_fdtol != NULL) { 686 /* 687 * Ask fdfree() to sleep to ensure that all relevant 688 * process leaders can be traversed in closef(). 689 */ 690 fdp->fd_holdleaderscount++; 691 holdleaders = 1; 692 } 693 } 694 695 /* 696 * Duplicate the source descriptor 697 */ 698 fdp->fd_ofiles[new] = fp; 699 fdp->fd_ofileflags[new] = fdp->fd_ofileflags[old] &~ UF_EXCLOSE; 700 if (new > fdp->fd_lastfile) 701 fdp->fd_lastfile = new; 702 *retval = new; 703 704 /* 705 * If we dup'd over a valid file, we now own the reference to it 706 * and must dispose of it using closef() semantics (as if a 707 * close() were performed on it). 708 * 709 * XXX this duplicates parts of close(). 710 */ 711 if (delfp != NULL) { 712 knote_fdclose(td, new); 713 FILEDESC_UNLOCK(fdp); 714 (void) closef(delfp, td); 715 if (holdleaders) { 716 FILEDESC_LOCK_FAST(fdp); 717 fdp->fd_holdleaderscount--; 718 if (fdp->fd_holdleaderscount == 0 && 719 fdp->fd_holdleaderswakeup != 0) { 720 fdp->fd_holdleaderswakeup = 0; 721 wakeup(&fdp->fd_holdleaderscount); 722 } 723 FILEDESC_UNLOCK_FAST(fdp); 724 } 725 } else { 726 FILEDESC_UNLOCK(fdp); 727 } 728 return (0); 729 } 730 731 /* 732 * If sigio is on the list associated with a process or process group, 733 * disable signalling from the device, remove sigio from the list and 734 * free sigio. 735 */ 736 void 737 funsetown(struct sigio **sigiop) 738 { 739 struct sigio *sigio; 740 741 SIGIO_LOCK(); 742 sigio = *sigiop; 743 if (sigio == NULL) { 744 SIGIO_UNLOCK(); 745 return; 746 } 747 *(sigio->sio_myref) = NULL; 748 if ((sigio)->sio_pgid < 0) { 749 struct pgrp *pg = (sigio)->sio_pgrp; 750 PGRP_LOCK(pg); 751 SLIST_REMOVE(&sigio->sio_pgrp->pg_sigiolst, sigio, 752 sigio, sio_pgsigio); 753 PGRP_UNLOCK(pg); 754 } else { 755 struct proc *p = (sigio)->sio_proc; 756 PROC_LOCK(p); 757 SLIST_REMOVE(&sigio->sio_proc->p_sigiolst, sigio, 758 sigio, sio_pgsigio); 759 PROC_UNLOCK(p); 760 } 761 SIGIO_UNLOCK(); 762 crfree(sigio->sio_ucred); 763 FREE(sigio, M_SIGIO); 764 } 765 766 /* 767 * Free a list of sigio structures. 768 * We only need to lock the SIGIO_LOCK because we have made ourselves 769 * inaccessible to callers of fsetown and therefore do not need to lock 770 * the proc or pgrp struct for the list manipulation. 771 */ 772 void 773 funsetownlst(struct sigiolst *sigiolst) 774 { 775 struct proc *p; 776 struct pgrp *pg; 777 struct sigio *sigio; 778 779 sigio = SLIST_FIRST(sigiolst); 780 if (sigio == NULL) 781 return; 782 p = NULL; 783 pg = NULL; 784 785 /* 786 * Every entry of the list should belong 787 * to a single proc or pgrp. 788 */ 789 if (sigio->sio_pgid < 0) { 790 pg = sigio->sio_pgrp; 791 PGRP_LOCK_ASSERT(pg, MA_NOTOWNED); 792 } else /* if (sigio->sio_pgid > 0) */ { 793 p = sigio->sio_proc; 794 PROC_LOCK_ASSERT(p, MA_NOTOWNED); 795 } 796 797 SIGIO_LOCK(); 798 while ((sigio = SLIST_FIRST(sigiolst)) != NULL) { 799 *(sigio->sio_myref) = NULL; 800 if (pg != NULL) { 801 KASSERT(sigio->sio_pgid < 0, 802 ("Proc sigio in pgrp sigio list")); 803 KASSERT(sigio->sio_pgrp == pg, 804 ("Bogus pgrp in sigio list")); 805 PGRP_LOCK(pg); 806 SLIST_REMOVE(&pg->pg_sigiolst, sigio, sigio, 807 sio_pgsigio); 808 PGRP_UNLOCK(pg); 809 } else /* if (p != NULL) */ { 810 KASSERT(sigio->sio_pgid > 0, 811 ("Pgrp sigio in proc sigio list")); 812 KASSERT(sigio->sio_proc == p, 813 ("Bogus proc in sigio list")); 814 PROC_LOCK(p); 815 SLIST_REMOVE(&p->p_sigiolst, sigio, sigio, 816 sio_pgsigio); 817 PROC_UNLOCK(p); 818 } 819 SIGIO_UNLOCK(); 820 crfree(sigio->sio_ucred); 821 FREE(sigio, M_SIGIO); 822 SIGIO_LOCK(); 823 } 824 SIGIO_UNLOCK(); 825 } 826 827 /* 828 * This is common code for FIOSETOWN ioctl called by fcntl(fd, F_SETOWN, arg). 829 * 830 * After permission checking, add a sigio structure to the sigio list for 831 * the process or process group. 832 */ 833 int 834 fsetown(pid_t pgid, struct sigio **sigiop) 835 { 836 struct proc *proc; 837 struct pgrp *pgrp; 838 struct sigio *sigio; 839 int ret; 840 841 if (pgid == 0) { 842 funsetown(sigiop); 843 return (0); 844 } 845 846 ret = 0; 847 848 /* Allocate and fill in the new sigio out of locks. */ 849 MALLOC(sigio, struct sigio *, sizeof(struct sigio), M_SIGIO, M_WAITOK); 850 sigio->sio_pgid = pgid; 851 sigio->sio_ucred = crhold(curthread->td_ucred); 852 sigio->sio_myref = sigiop; 853 854 sx_slock(&proctree_lock); 855 if (pgid > 0) { 856 proc = pfind(pgid); 857 if (proc == NULL) { 858 ret = ESRCH; 859 goto fail; 860 } 861 862 /* 863 * Policy - Don't allow a process to FSETOWN a process 864 * in another session. 865 * 866 * Remove this test to allow maximum flexibility or 867 * restrict FSETOWN to the current process or process 868 * group for maximum safety. 869 */ 870 PROC_UNLOCK(proc); 871 if (proc->p_session != curthread->td_proc->p_session) { 872 ret = EPERM; 873 goto fail; 874 } 875 876 pgrp = NULL; 877 } else /* if (pgid < 0) */ { 878 pgrp = pgfind(-pgid); 879 if (pgrp == NULL) { 880 ret = ESRCH; 881 goto fail; 882 } 883 PGRP_UNLOCK(pgrp); 884 885 /* 886 * Policy - Don't allow a process to FSETOWN a process 887 * in another session. 888 * 889 * Remove this test to allow maximum flexibility or 890 * restrict FSETOWN to the current process or process 891 * group for maximum safety. 892 */ 893 if (pgrp->pg_session != curthread->td_proc->p_session) { 894 ret = EPERM; 895 goto fail; 896 } 897 898 proc = NULL; 899 } 900 funsetown(sigiop); 901 if (pgid > 0) { 902 PROC_LOCK(proc); 903 /* 904 * Since funsetownlst() is called without the proctree 905 * locked, we need to check for P_WEXIT. 906 * XXX: is ESRCH correct? 907 */ 908 if ((proc->p_flag & P_WEXIT) != 0) { 909 PROC_UNLOCK(proc); 910 ret = ESRCH; 911 goto fail; 912 } 913 SLIST_INSERT_HEAD(&proc->p_sigiolst, sigio, sio_pgsigio); 914 sigio->sio_proc = proc; 915 PROC_UNLOCK(proc); 916 } else { 917 PGRP_LOCK(pgrp); 918 SLIST_INSERT_HEAD(&pgrp->pg_sigiolst, sigio, sio_pgsigio); 919 sigio->sio_pgrp = pgrp; 920 PGRP_UNLOCK(pgrp); 921 } 922 sx_sunlock(&proctree_lock); 923 SIGIO_LOCK(); 924 *sigiop = sigio; 925 SIGIO_UNLOCK(); 926 return (0); 927 928 fail: 929 sx_sunlock(&proctree_lock); 930 crfree(sigio->sio_ucred); 931 FREE(sigio, M_SIGIO); 932 return (ret); 933 } 934 935 /* 936 * This is common code for FIOGETOWN ioctl called by fcntl(fd, F_GETOWN, arg). 937 */ 938 pid_t 939 fgetown(sigiop) 940 struct sigio **sigiop; 941 { 942 pid_t pgid; 943 944 SIGIO_LOCK(); 945 pgid = (*sigiop != NULL) ? (*sigiop)->sio_pgid : 0; 946 SIGIO_UNLOCK(); 947 return (pgid); 948 } 949 950 /* 951 * Close a file descriptor. 952 */ 953 #ifndef _SYS_SYSPROTO_H_ 954 struct close_args { 955 int fd; 956 }; 957 #endif 958 /* 959 * MPSAFE 960 */ 961 /* ARGSUSED */ 962 int 963 close(td, uap) 964 struct thread *td; 965 struct close_args *uap; 966 { 967 struct filedesc *fdp; 968 struct file *fp; 969 int fd, error; 970 int holdleaders; 971 972 fd = uap->fd; 973 error = 0; 974 holdleaders = 0; 975 fdp = td->td_proc->p_fd; 976 FILEDESC_LOCK(fdp); 977 if ((unsigned)fd >= fdp->fd_nfiles || 978 (fp = fdp->fd_ofiles[fd]) == NULL) { 979 FILEDESC_UNLOCK(fdp); 980 return (EBADF); 981 } 982 fdp->fd_ofiles[fd] = NULL; 983 fdp->fd_ofileflags[fd] = 0; 984 fdunused(fdp, fd); 985 if (td->td_proc->p_fdtol != NULL) { 986 /* 987 * Ask fdfree() to sleep to ensure that all relevant 988 * process leaders can be traversed in closef(). 989 */ 990 fdp->fd_holdleaderscount++; 991 holdleaders = 1; 992 } 993 994 /* 995 * We now hold the fp reference that used to be owned by the descriptor 996 * array. 997 * We have to unlock the FILEDESC *AFTER* knote_fdclose to prevent a 998 * race of the fd getting opened, a knote added, and deleteing a knote 999 * for the new fd. 1000 */ 1001 knote_fdclose(td, fd); 1002 FILEDESC_UNLOCK(fdp); 1003 1004 error = closef(fp, td); 1005 if (holdleaders) { 1006 FILEDESC_LOCK_FAST(fdp); 1007 fdp->fd_holdleaderscount--; 1008 if (fdp->fd_holdleaderscount == 0 && 1009 fdp->fd_holdleaderswakeup != 0) { 1010 fdp->fd_holdleaderswakeup = 0; 1011 wakeup(&fdp->fd_holdleaderscount); 1012 } 1013 FILEDESC_UNLOCK_FAST(fdp); 1014 } 1015 return (error); 1016 } 1017 1018 #if defined(COMPAT_43) 1019 /* 1020 * Return status information about a file descriptor. 1021 */ 1022 #ifndef _SYS_SYSPROTO_H_ 1023 struct ofstat_args { 1024 int fd; 1025 struct ostat *sb; 1026 }; 1027 #endif 1028 /* 1029 * MPSAFE 1030 */ 1031 /* ARGSUSED */ 1032 int 1033 ofstat(struct thread *td, struct ofstat_args *uap) 1034 { 1035 struct ostat oub; 1036 struct stat ub; 1037 int error; 1038 1039 error = kern_fstat(td, uap->fd, &ub); 1040 if (error == 0) { 1041 cvtstat(&ub, &oub); 1042 error = copyout(&oub, uap->sb, sizeof(oub)); 1043 } 1044 return (error); 1045 } 1046 #endif /* COMPAT_43 */ 1047 1048 /* 1049 * Return status information about a file descriptor. 1050 */ 1051 #ifndef _SYS_SYSPROTO_H_ 1052 struct fstat_args { 1053 int fd; 1054 struct stat *sb; 1055 }; 1056 #endif 1057 /* 1058 * MPSAFE 1059 */ 1060 /* ARGSUSED */ 1061 int 1062 fstat(struct thread *td, struct fstat_args *uap) 1063 { 1064 struct stat ub; 1065 int error; 1066 1067 error = kern_fstat(td, uap->fd, &ub); 1068 if (error == 0) 1069 error = copyout(&ub, uap->sb, sizeof(ub)); 1070 return (error); 1071 } 1072 1073 int 1074 kern_fstat(struct thread *td, int fd, struct stat *sbp) 1075 { 1076 struct file *fp; 1077 int error; 1078 1079 if ((error = fget(td, fd, &fp)) != 0) 1080 return (error); 1081 error = fo_stat(fp, sbp, td->td_ucred, td); 1082 fdrop(fp, td); 1083 return (error); 1084 } 1085 1086 /* 1087 * Return status information about a file descriptor. 1088 */ 1089 #ifndef _SYS_SYSPROTO_H_ 1090 struct nfstat_args { 1091 int fd; 1092 struct nstat *sb; 1093 }; 1094 #endif 1095 /* 1096 * MPSAFE 1097 */ 1098 /* ARGSUSED */ 1099 int 1100 nfstat(struct thread *td, struct nfstat_args *uap) 1101 { 1102 struct nstat nub; 1103 struct stat ub; 1104 int error; 1105 1106 error = kern_fstat(td, uap->fd, &ub); 1107 if (error == 0) { 1108 cvtnstat(&ub, &nub); 1109 error = copyout(&nub, uap->sb, sizeof(nub)); 1110 } 1111 return (error); 1112 } 1113 1114 /* 1115 * Return pathconf information about a file descriptor. 1116 */ 1117 #ifndef _SYS_SYSPROTO_H_ 1118 struct fpathconf_args { 1119 int fd; 1120 int name; 1121 }; 1122 #endif 1123 /* 1124 * MPSAFE 1125 */ 1126 /* ARGSUSED */ 1127 int 1128 fpathconf(struct thread *td, struct fpathconf_args *uap) 1129 { 1130 struct file *fp; 1131 struct vnode *vp; 1132 int error; 1133 1134 if ((error = fget(td, uap->fd, &fp)) != 0) 1135 return (error); 1136 1137 /* If asynchronous I/O is available, it works for all descriptors. */ 1138 if (uap->name == _PC_ASYNC_IO) { 1139 td->td_retval[0] = async_io_version; 1140 goto out; 1141 } 1142 vp = fp->f_vnode; 1143 if (vp != NULL) { 1144 int vfslocked; 1145 vfslocked = VFS_LOCK_GIANT(vp->v_mount); 1146 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 1147 error = VOP_PATHCONF(vp, uap->name, td->td_retval); 1148 VOP_UNLOCK(vp, 0, td); 1149 VFS_UNLOCK_GIANT(vfslocked); 1150 } else if (fp->f_type == DTYPE_PIPE || fp->f_type == DTYPE_SOCKET) { 1151 if (uap->name != _PC_PIPE_BUF) { 1152 error = EINVAL; 1153 } else { 1154 td->td_retval[0] = PIPE_BUF; 1155 error = 0; 1156 } 1157 } else { 1158 error = EOPNOTSUPP; 1159 } 1160 out: 1161 fdrop(fp, td); 1162 return (error); 1163 } 1164 1165 /* 1166 * Grow the file table to accomodate (at least) nfd descriptors. This may 1167 * block and drop the filedesc lock, but it will reacquire it before 1168 * returning. 1169 */ 1170 static void 1171 fdgrowtable(struct filedesc *fdp, int nfd) 1172 { 1173 struct file **ntable; 1174 char *nfileflags; 1175 int nnfiles, onfiles; 1176 NDSLOTTYPE *nmap; 1177 1178 FILEDESC_LOCK_ASSERT(fdp, MA_OWNED); 1179 1180 KASSERT(fdp->fd_nfiles > 0, 1181 ("zero-length file table")); 1182 1183 /* compute the size of the new table */ 1184 onfiles = fdp->fd_nfiles; 1185 nnfiles = NDSLOTS(nfd) * NDENTRIES; /* round up */ 1186 if (nnfiles <= onfiles) 1187 /* the table is already large enough */ 1188 return; 1189 1190 /* allocate a new table and (if required) new bitmaps */ 1191 FILEDESC_UNLOCK(fdp); 1192 MALLOC(ntable, struct file **, nnfiles * OFILESIZE, 1193 M_FILEDESC, M_ZERO | M_WAITOK); 1194 nfileflags = (char *)&ntable[nnfiles]; 1195 if (NDSLOTS(nnfiles) > NDSLOTS(onfiles)) 1196 MALLOC(nmap, NDSLOTTYPE *, NDSLOTS(nnfiles) * NDSLOTSIZE, 1197 M_FILEDESC, M_ZERO | M_WAITOK); 1198 else 1199 nmap = NULL; 1200 FILEDESC_LOCK(fdp); 1201 1202 /* 1203 * We now have new tables ready to go. Since we dropped the 1204 * filedesc lock to call malloc(), watch out for a race. 1205 */ 1206 onfiles = fdp->fd_nfiles; 1207 if (onfiles >= nnfiles) { 1208 /* we lost the race, but that's OK */ 1209 free(ntable, M_FILEDESC); 1210 if (nmap != NULL) 1211 free(nmap, M_FILEDESC); 1212 return; 1213 } 1214 bcopy(fdp->fd_ofiles, ntable, onfiles * sizeof(*ntable)); 1215 bcopy(fdp->fd_ofileflags, nfileflags, onfiles); 1216 if (onfiles > NDFILE) 1217 free(fdp->fd_ofiles, M_FILEDESC); 1218 fdp->fd_ofiles = ntable; 1219 fdp->fd_ofileflags = nfileflags; 1220 if (NDSLOTS(nnfiles) > NDSLOTS(onfiles)) { 1221 bcopy(fdp->fd_map, nmap, NDSLOTS(onfiles) * sizeof(*nmap)); 1222 if (NDSLOTS(onfiles) > NDSLOTS(NDFILE)) 1223 free(fdp->fd_map, M_FILEDESC); 1224 fdp->fd_map = nmap; 1225 } 1226 fdp->fd_nfiles = nnfiles; 1227 } 1228 1229 /* 1230 * Allocate a file descriptor for the process. 1231 */ 1232 int 1233 fdalloc(struct thread *td, int minfd, int *result) 1234 { 1235 struct proc *p = td->td_proc; 1236 struct filedesc *fdp = p->p_fd; 1237 int fd = -1, maxfd; 1238 1239 FILEDESC_LOCK_ASSERT(fdp, MA_OWNED); 1240 1241 if (fdp->fd_freefile > minfd) 1242 minfd = fdp->fd_freefile; 1243 1244 PROC_LOCK(p); 1245 maxfd = min((int)lim_cur(p, RLIMIT_NOFILE), maxfilesperproc); 1246 PROC_UNLOCK(p); 1247 1248 /* 1249 * Search the bitmap for a free descriptor. If none is found, try 1250 * to grow the file table. Keep at it until we either get a file 1251 * descriptor or run into process or system limits; fdgrowtable() 1252 * may drop the filedesc lock, so we're in a race. 1253 */ 1254 for (;;) { 1255 fd = fd_first_free(fdp, minfd, fdp->fd_nfiles); 1256 if (fd >= maxfd) 1257 return (EMFILE); 1258 if (fd < fdp->fd_nfiles) 1259 break; 1260 fdgrowtable(fdp, min(fdp->fd_nfiles * 2, maxfd)); 1261 } 1262 1263 /* 1264 * Perform some sanity checks, then mark the file descriptor as 1265 * used and return it to the caller. 1266 */ 1267 KASSERT(!fdisused(fdp, fd), 1268 ("fd_first_free() returned non-free descriptor")); 1269 KASSERT(fdp->fd_ofiles[fd] == NULL, 1270 ("free descriptor isn't")); 1271 fdp->fd_ofileflags[fd] = 0; /* XXX needed? */ 1272 fdused(fdp, fd); 1273 *result = fd; 1274 return (0); 1275 } 1276 1277 /* 1278 * Check to see whether n user file descriptors 1279 * are available to the process p. 1280 */ 1281 int 1282 fdavail(struct thread *td, int n) 1283 { 1284 struct proc *p = td->td_proc; 1285 struct filedesc *fdp = td->td_proc->p_fd; 1286 struct file **fpp; 1287 int i, lim, last; 1288 1289 FILEDESC_LOCK_ASSERT(fdp, MA_OWNED); 1290 1291 PROC_LOCK(p); 1292 lim = min((int)lim_cur(p, RLIMIT_NOFILE), maxfilesperproc); 1293 PROC_UNLOCK(p); 1294 if ((i = lim - fdp->fd_nfiles) > 0 && (n -= i) <= 0) 1295 return (1); 1296 last = min(fdp->fd_nfiles, lim); 1297 fpp = &fdp->fd_ofiles[fdp->fd_freefile]; 1298 for (i = last - fdp->fd_freefile; --i >= 0; fpp++) { 1299 if (*fpp == NULL && --n <= 0) 1300 return (1); 1301 } 1302 return (0); 1303 } 1304 1305 /* 1306 * Create a new open file structure and allocate 1307 * a file decriptor for the process that refers to it. 1308 * We add one reference to the file for the descriptor table 1309 * and one reference for resultfp. This is to prevent us being 1310 * preempted and the entry in the descriptor table closed after 1311 * we release the FILEDESC lock. 1312 */ 1313 int 1314 falloc(struct thread *td, struct file **resultfp, int *resultfd) 1315 { 1316 struct proc *p = td->td_proc; 1317 struct file *fp, *fq; 1318 int error, i; 1319 int maxuserfiles = maxfiles - (maxfiles / 20); 1320 static struct timeval lastfail; 1321 static int curfail; 1322 1323 fp = uma_zalloc(file_zone, M_WAITOK | M_ZERO); 1324 sx_xlock(&filelist_lock); 1325 if ((openfiles >= maxuserfiles && (td->td_ucred->cr_ruid != 0 || 1326 jailed(td->td_ucred))) || openfiles >= maxfiles) { 1327 if (ppsratecheck(&lastfail, &curfail, 1)) { 1328 printf("kern.maxfiles limit exceeded by uid %i, please see tuning(7).\n", 1329 td->td_ucred->cr_ruid); 1330 } 1331 sx_xunlock(&filelist_lock); 1332 uma_zfree(file_zone, fp); 1333 return (ENFILE); 1334 } 1335 openfiles++; 1336 1337 /* 1338 * If the process has file descriptor zero open, add the new file 1339 * descriptor to the list of open files at that point, otherwise 1340 * put it at the front of the list of open files. 1341 */ 1342 fp->f_mtxp = mtx_pool_alloc(mtxpool_sleep); 1343 fp->f_count = 1; 1344 if (resultfp) 1345 fp->f_count++; 1346 fp->f_cred = crhold(td->td_ucred); 1347 fp->f_ops = &badfileops; 1348 fp->f_data = NULL; 1349 fp->f_vnode = NULL; 1350 FILEDESC_LOCK(p->p_fd); 1351 if ((fq = p->p_fd->fd_ofiles[0])) { 1352 LIST_INSERT_AFTER(fq, fp, f_list); 1353 } else { 1354 LIST_INSERT_HEAD(&filehead, fp, f_list); 1355 } 1356 sx_xunlock(&filelist_lock); 1357 if ((error = fdalloc(td, 0, &i))) { 1358 FILEDESC_UNLOCK(p->p_fd); 1359 fdrop(fp, td); 1360 if (resultfp) 1361 fdrop(fp, td); 1362 return (error); 1363 } 1364 p->p_fd->fd_ofiles[i] = fp; 1365 FILEDESC_UNLOCK(p->p_fd); 1366 if (resultfp) 1367 *resultfp = fp; 1368 if (resultfd) 1369 *resultfd = i; 1370 return (0); 1371 } 1372 1373 /* 1374 * Build a new filedesc structure from another. 1375 * Copy the current, root, and jail root vnode references. 1376 */ 1377 struct filedesc * 1378 fdinit(struct filedesc *fdp) 1379 { 1380 struct filedesc0 *newfdp; 1381 1382 newfdp = malloc(sizeof *newfdp, M_FILEDESC, M_WAITOK | M_ZERO); 1383 mtx_init(&newfdp->fd_fd.fd_mtx, FILEDESC_LOCK_DESC, NULL, MTX_DEF); 1384 if (fdp != NULL) { 1385 FILEDESC_LOCK(fdp); 1386 newfdp->fd_fd.fd_cdir = fdp->fd_cdir; 1387 if (newfdp->fd_fd.fd_cdir) 1388 VREF(newfdp->fd_fd.fd_cdir); 1389 newfdp->fd_fd.fd_rdir = fdp->fd_rdir; 1390 if (newfdp->fd_fd.fd_rdir) 1391 VREF(newfdp->fd_fd.fd_rdir); 1392 newfdp->fd_fd.fd_jdir = fdp->fd_jdir; 1393 if (newfdp->fd_fd.fd_jdir) 1394 VREF(newfdp->fd_fd.fd_jdir); 1395 FILEDESC_UNLOCK(fdp); 1396 } 1397 1398 /* Create the file descriptor table. */ 1399 newfdp->fd_fd.fd_refcnt = 1; 1400 newfdp->fd_fd.fd_holdcnt = 1; 1401 newfdp->fd_fd.fd_cmask = CMASK; 1402 newfdp->fd_fd.fd_ofiles = newfdp->fd_dfiles; 1403 newfdp->fd_fd.fd_ofileflags = newfdp->fd_dfileflags; 1404 newfdp->fd_fd.fd_nfiles = NDFILE; 1405 newfdp->fd_fd.fd_map = newfdp->fd_dmap; 1406 return (&newfdp->fd_fd); 1407 } 1408 1409 static struct filedesc * 1410 fdhold(struct proc *p) 1411 { 1412 struct filedesc *fdp; 1413 1414 mtx_lock(&fdesc_mtx); 1415 fdp = p->p_fd; 1416 if (fdp != NULL) 1417 fdp->fd_holdcnt++; 1418 mtx_unlock(&fdesc_mtx); 1419 return (fdp); 1420 } 1421 1422 static void 1423 fddrop(struct filedesc *fdp) 1424 { 1425 int i; 1426 1427 mtx_lock(&fdesc_mtx); 1428 i = --fdp->fd_holdcnt; 1429 mtx_unlock(&fdesc_mtx); 1430 if (i > 0) 1431 return; 1432 1433 mtx_destroy(&fdp->fd_mtx); 1434 FREE(fdp, M_FILEDESC); 1435 } 1436 1437 /* 1438 * Share a filedesc structure. 1439 */ 1440 struct filedesc * 1441 fdshare(struct filedesc *fdp) 1442 { 1443 FILEDESC_LOCK_FAST(fdp); 1444 fdp->fd_refcnt++; 1445 FILEDESC_UNLOCK_FAST(fdp); 1446 return (fdp); 1447 } 1448 1449 /* 1450 * Unshare a filedesc structure, if necessary by making a copy 1451 */ 1452 void 1453 fdunshare(struct proc *p, struct thread *td) 1454 { 1455 1456 FILEDESC_LOCK_FAST(p->p_fd); 1457 if (p->p_fd->fd_refcnt > 1) { 1458 struct filedesc *tmp; 1459 1460 FILEDESC_UNLOCK_FAST(p->p_fd); 1461 tmp = fdcopy(p->p_fd); 1462 fdfree(td); 1463 p->p_fd = tmp; 1464 } else 1465 FILEDESC_UNLOCK_FAST(p->p_fd); 1466 } 1467 1468 /* 1469 * Copy a filedesc structure. 1470 * A NULL pointer in returns a NULL reference, this is to ease callers, 1471 * not catch errors. 1472 */ 1473 struct filedesc * 1474 fdcopy(struct filedesc *fdp) 1475 { 1476 struct filedesc *newfdp; 1477 int i; 1478 1479 /* Certain daemons might not have file descriptors. */ 1480 if (fdp == NULL) 1481 return (NULL); 1482 1483 newfdp = fdinit(fdp); 1484 FILEDESC_LOCK_FAST(fdp); 1485 while (fdp->fd_lastfile >= newfdp->fd_nfiles) { 1486 FILEDESC_UNLOCK_FAST(fdp); 1487 FILEDESC_LOCK(newfdp); 1488 fdgrowtable(newfdp, fdp->fd_lastfile + 1); 1489 FILEDESC_UNLOCK(newfdp); 1490 FILEDESC_LOCK_FAST(fdp); 1491 } 1492 /* copy everything except kqueue descriptors */ 1493 newfdp->fd_freefile = -1; 1494 for (i = 0; i <= fdp->fd_lastfile; ++i) { 1495 if (fdisused(fdp, i) && 1496 fdp->fd_ofiles[i]->f_type != DTYPE_KQUEUE) { 1497 newfdp->fd_ofiles[i] = fdp->fd_ofiles[i]; 1498 newfdp->fd_ofileflags[i] = fdp->fd_ofileflags[i]; 1499 fhold(newfdp->fd_ofiles[i]); 1500 newfdp->fd_lastfile = i; 1501 } else { 1502 if (newfdp->fd_freefile == -1) 1503 newfdp->fd_freefile = i; 1504 } 1505 } 1506 FILEDESC_UNLOCK_FAST(fdp); 1507 FILEDESC_LOCK(newfdp); 1508 for (i = 0; i <= newfdp->fd_lastfile; ++i) 1509 if (newfdp->fd_ofiles[i] != NULL) 1510 fdused(newfdp, i); 1511 FILEDESC_UNLOCK(newfdp); 1512 FILEDESC_LOCK_FAST(fdp); 1513 if (newfdp->fd_freefile == -1) 1514 newfdp->fd_freefile = i; 1515 newfdp->fd_cmask = fdp->fd_cmask; 1516 FILEDESC_UNLOCK_FAST(fdp); 1517 return (newfdp); 1518 } 1519 1520 /* 1521 * Release a filedesc structure. 1522 */ 1523 void 1524 fdfree(struct thread *td) 1525 { 1526 struct filedesc *fdp; 1527 struct file **fpp; 1528 int i; 1529 struct filedesc_to_leader *fdtol; 1530 struct file *fp; 1531 struct vnode *vp; 1532 struct flock lf; 1533 1534 /* Certain daemons might not have file descriptors. */ 1535 fdp = td->td_proc->p_fd; 1536 if (fdp == NULL) 1537 return; 1538 1539 /* Check for special need to clear POSIX style locks */ 1540 fdtol = td->td_proc->p_fdtol; 1541 if (fdtol != NULL) { 1542 FILEDESC_LOCK(fdp); 1543 KASSERT(fdtol->fdl_refcount > 0, 1544 ("filedesc_to_refcount botch: fdl_refcount=%d", 1545 fdtol->fdl_refcount)); 1546 if (fdtol->fdl_refcount == 1 && 1547 (td->td_proc->p_leader->p_flag & P_ADVLOCK) != 0) { 1548 for (i = 0, fpp = fdp->fd_ofiles; 1549 i <= fdp->fd_lastfile; 1550 i++, fpp++) { 1551 if (*fpp == NULL || 1552 (*fpp)->f_type != DTYPE_VNODE) 1553 continue; 1554 fp = *fpp; 1555 fhold(fp); 1556 FILEDESC_UNLOCK(fdp); 1557 lf.l_whence = SEEK_SET; 1558 lf.l_start = 0; 1559 lf.l_len = 0; 1560 lf.l_type = F_UNLCK; 1561 vp = fp->f_vnode; 1562 VFS_ASSERT_GIANT(vp->v_mount); 1563 (void) VOP_ADVLOCK(vp, 1564 (caddr_t)td->td_proc-> 1565 p_leader, 1566 F_UNLCK, 1567 &lf, 1568 F_POSIX); 1569 FILEDESC_LOCK(fdp); 1570 fdrop(fp, td); 1571 fpp = fdp->fd_ofiles + i; 1572 } 1573 } 1574 retry: 1575 if (fdtol->fdl_refcount == 1) { 1576 if (fdp->fd_holdleaderscount > 0 && 1577 (td->td_proc->p_leader->p_flag & P_ADVLOCK) != 0) { 1578 /* 1579 * close() or do_dup() has cleared a reference 1580 * in a shared file descriptor table. 1581 */ 1582 fdp->fd_holdleaderswakeup = 1; 1583 msleep(&fdp->fd_holdleaderscount, &fdp->fd_mtx, 1584 PLOCK, "fdlhold", 0); 1585 goto retry; 1586 } 1587 if (fdtol->fdl_holdcount > 0) { 1588 /* 1589 * Ensure that fdtol->fdl_leader 1590 * remains valid in closef(). 1591 */ 1592 fdtol->fdl_wakeup = 1; 1593 msleep(fdtol, &fdp->fd_mtx, 1594 PLOCK, "fdlhold", 0); 1595 goto retry; 1596 } 1597 } 1598 fdtol->fdl_refcount--; 1599 if (fdtol->fdl_refcount == 0 && 1600 fdtol->fdl_holdcount == 0) { 1601 fdtol->fdl_next->fdl_prev = fdtol->fdl_prev; 1602 fdtol->fdl_prev->fdl_next = fdtol->fdl_next; 1603 } else 1604 fdtol = NULL; 1605 td->td_proc->p_fdtol = NULL; 1606 FILEDESC_UNLOCK(fdp); 1607 if (fdtol != NULL) 1608 FREE(fdtol, M_FILEDESC_TO_LEADER); 1609 } 1610 FILEDESC_LOCK_FAST(fdp); 1611 i = --fdp->fd_refcnt; 1612 FILEDESC_UNLOCK_FAST(fdp); 1613 if (i > 0) 1614 return; 1615 /* 1616 * We are the last reference to the structure, so we can 1617 * safely assume it will not change out from under us. 1618 */ 1619 fpp = fdp->fd_ofiles; 1620 for (i = fdp->fd_lastfile; i-- >= 0; fpp++) { 1621 if (*fpp) 1622 (void) closef(*fpp, td); 1623 } 1624 FILEDESC_LOCK(fdp); 1625 1626 /* XXX This should happen earlier. */ 1627 mtx_lock(&fdesc_mtx); 1628 td->td_proc->p_fd = NULL; 1629 mtx_unlock(&fdesc_mtx); 1630 1631 if (fdp->fd_nfiles > NDFILE) 1632 FREE(fdp->fd_ofiles, M_FILEDESC); 1633 if (NDSLOTS(fdp->fd_nfiles) > NDSLOTS(NDFILE)) 1634 FREE(fdp->fd_map, M_FILEDESC); 1635 1636 fdp->fd_nfiles = 0; 1637 1638 if (fdp->fd_cdir) 1639 vrele(fdp->fd_cdir); 1640 fdp->fd_cdir = NULL; 1641 if (fdp->fd_rdir) 1642 vrele(fdp->fd_rdir); 1643 fdp->fd_rdir = NULL; 1644 if (fdp->fd_jdir) 1645 vrele(fdp->fd_jdir); 1646 fdp->fd_jdir = NULL; 1647 1648 FILEDESC_UNLOCK(fdp); 1649 1650 fddrop(fdp); 1651 } 1652 1653 /* 1654 * For setugid programs, we don't want to people to use that setugidness 1655 * to generate error messages which write to a file which otherwise would 1656 * otherwise be off-limits to the process. We check for filesystems where 1657 * the vnode can change out from under us after execve (like [lin]procfs). 1658 * 1659 * Since setugidsafety calls this only for fd 0, 1 and 2, this check is 1660 * sufficient. We also don't check for setugidness since we know we are. 1661 */ 1662 static int 1663 is_unsafe(struct file *fp) 1664 { 1665 if (fp->f_type == DTYPE_VNODE) { 1666 struct vnode *vp = fp->f_vnode; 1667 1668 if ((vp->v_vflag & VV_PROCDEP) != 0) 1669 return (1); 1670 } 1671 return (0); 1672 } 1673 1674 /* 1675 * Make this setguid thing safe, if at all possible. 1676 */ 1677 void 1678 setugidsafety(struct thread *td) 1679 { 1680 struct filedesc *fdp; 1681 int i; 1682 1683 /* Certain daemons might not have file descriptors. */ 1684 fdp = td->td_proc->p_fd; 1685 if (fdp == NULL) 1686 return; 1687 1688 /* 1689 * Note: fdp->fd_ofiles may be reallocated out from under us while 1690 * we are blocked in a close. Be careful! 1691 */ 1692 FILEDESC_LOCK(fdp); 1693 for (i = 0; i <= fdp->fd_lastfile; i++) { 1694 if (i > 2) 1695 break; 1696 if (fdp->fd_ofiles[i] && is_unsafe(fdp->fd_ofiles[i])) { 1697 struct file *fp; 1698 1699 knote_fdclose(td, i); 1700 /* 1701 * NULL-out descriptor prior to close to avoid 1702 * a race while close blocks. 1703 */ 1704 fp = fdp->fd_ofiles[i]; 1705 fdp->fd_ofiles[i] = NULL; 1706 fdp->fd_ofileflags[i] = 0; 1707 fdunused(fdp, i); 1708 FILEDESC_UNLOCK(fdp); 1709 (void) closef(fp, td); 1710 FILEDESC_LOCK(fdp); 1711 } 1712 } 1713 FILEDESC_UNLOCK(fdp); 1714 } 1715 1716 void 1717 fdclose(struct filedesc *fdp, struct file *fp, int idx, struct thread *td) 1718 { 1719 1720 FILEDESC_LOCK(fdp); 1721 if (fdp->fd_ofiles[idx] == fp) { 1722 fdp->fd_ofiles[idx] = NULL; 1723 fdunused(fdp, idx); 1724 FILEDESC_UNLOCK(fdp); 1725 fdrop(fp, td); 1726 } else { 1727 FILEDESC_UNLOCK(fdp); 1728 } 1729 } 1730 1731 /* 1732 * Close any files on exec? 1733 */ 1734 void 1735 fdcloseexec(struct thread *td) 1736 { 1737 struct filedesc *fdp; 1738 int i; 1739 1740 /* Certain daemons might not have file descriptors. */ 1741 fdp = td->td_proc->p_fd; 1742 if (fdp == NULL) 1743 return; 1744 1745 FILEDESC_LOCK(fdp); 1746 1747 /* 1748 * We cannot cache fd_ofiles or fd_ofileflags since operations 1749 * may block and rip them out from under us. 1750 */ 1751 for (i = 0; i <= fdp->fd_lastfile; i++) { 1752 if (fdp->fd_ofiles[i] != NULL && 1753 (fdp->fd_ofileflags[i] & UF_EXCLOSE)) { 1754 struct file *fp; 1755 1756 knote_fdclose(td, i); 1757 /* 1758 * NULL-out descriptor prior to close to avoid 1759 * a race while close blocks. 1760 */ 1761 fp = fdp->fd_ofiles[i]; 1762 fdp->fd_ofiles[i] = NULL; 1763 fdp->fd_ofileflags[i] = 0; 1764 fdunused(fdp, i); 1765 FILEDESC_UNLOCK(fdp); 1766 (void) closef(fp, td); 1767 FILEDESC_LOCK(fdp); 1768 } 1769 } 1770 FILEDESC_UNLOCK(fdp); 1771 } 1772 1773 /* 1774 * It is unsafe for set[ug]id processes to be started with file 1775 * descriptors 0..2 closed, as these descriptors are given implicit 1776 * significance in the Standard C library. fdcheckstd() will create a 1777 * descriptor referencing /dev/null for each of stdin, stdout, and 1778 * stderr that is not already open. 1779 */ 1780 int 1781 fdcheckstd(struct thread *td) 1782 { 1783 struct nameidata nd; 1784 struct filedesc *fdp; 1785 struct file *fp; 1786 register_t retval; 1787 int fd, i, error, flags, devnull; 1788 1789 fdp = td->td_proc->p_fd; 1790 if (fdp == NULL) 1791 return (0); 1792 KASSERT(fdp->fd_refcnt == 1, ("the fdtable should not be shared")); 1793 devnull = -1; 1794 error = 0; 1795 for (i = 0; i < 3; i++) { 1796 if (fdp->fd_ofiles[i] != NULL) 1797 continue; 1798 if (devnull < 0) { 1799 int vfslocked; 1800 error = falloc(td, &fp, &fd); 1801 if (error != 0) 1802 break; 1803 /* Note extra ref on `fp' held for us by falloc(). */ 1804 KASSERT(fd == i, ("oof, we didn't get our fd")); 1805 NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, 1806 "/dev/null", td); 1807 flags = FREAD | FWRITE; 1808 error = vn_open(&nd, &flags, 0, fd); 1809 if (error != 0) { 1810 /* 1811 * Someone may have closed the entry in the 1812 * file descriptor table, so check it hasn't 1813 * changed before dropping the reference count. 1814 */ 1815 FILEDESC_LOCK(fdp); 1816 KASSERT(fdp->fd_ofiles[fd] == fp, 1817 ("table not shared, how did it change?")); 1818 fdp->fd_ofiles[fd] = NULL; 1819 fdunused(fdp, fd); 1820 FILEDESC_UNLOCK(fdp); 1821 fdrop(fp, td); 1822 fdrop(fp, td); 1823 break; 1824 } 1825 vfslocked = NDHASGIANT(&nd); 1826 NDFREE(&nd, NDF_ONLY_PNBUF); 1827 fp->f_flag = flags; 1828 fp->f_vnode = nd.ni_vp; 1829 if (fp->f_data == NULL) 1830 fp->f_data = nd.ni_vp; 1831 if (fp->f_ops == &badfileops) 1832 fp->f_ops = &vnops; 1833 fp->f_type = DTYPE_VNODE; 1834 VOP_UNLOCK(nd.ni_vp, 0, td); 1835 VFS_UNLOCK_GIANT(vfslocked); 1836 devnull = fd; 1837 fdrop(fp, td); 1838 } else { 1839 error = do_dup(td, DUP_FIXED, devnull, i, &retval); 1840 if (error != 0) 1841 break; 1842 } 1843 } 1844 return (error); 1845 } 1846 1847 /* 1848 * Internal form of close. 1849 * Decrement reference count on file structure. 1850 * Note: td may be NULL when closing a file that was being passed in a 1851 * message. 1852 * 1853 * XXXRW: Giant is not required for the caller, but often will be held; this 1854 * makes it moderately likely the Giant will be recursed in the VFS case. 1855 */ 1856 int 1857 closef(struct file *fp, struct thread *td) 1858 { 1859 struct vnode *vp; 1860 struct flock lf; 1861 struct filedesc_to_leader *fdtol; 1862 struct filedesc *fdp; 1863 1864 /* 1865 * POSIX record locking dictates that any close releases ALL 1866 * locks owned by this process. This is handled by setting 1867 * a flag in the unlock to free ONLY locks obeying POSIX 1868 * semantics, and not to free BSD-style file locks. 1869 * If the descriptor was in a message, POSIX-style locks 1870 * aren't passed with the descriptor. 1871 */ 1872 if (fp->f_type == DTYPE_VNODE) { 1873 int vfslocked; 1874 1875 vp = fp->f_vnode; 1876 vfslocked = VFS_LOCK_GIANT(vp->v_mount); 1877 if ((td->td_proc->p_leader->p_flag & P_ADVLOCK) != 0) { 1878 lf.l_whence = SEEK_SET; 1879 lf.l_start = 0; 1880 lf.l_len = 0; 1881 lf.l_type = F_UNLCK; 1882 (void) VOP_ADVLOCK(vp, (caddr_t)td->td_proc->p_leader, 1883 F_UNLCK, &lf, F_POSIX); 1884 } 1885 fdtol = td->td_proc->p_fdtol; 1886 if (fdtol != NULL) { 1887 /* 1888 * Handle special case where file descriptor table 1889 * is shared between multiple process leaders. 1890 */ 1891 fdp = td->td_proc->p_fd; 1892 FILEDESC_LOCK(fdp); 1893 for (fdtol = fdtol->fdl_next; 1894 fdtol != td->td_proc->p_fdtol; 1895 fdtol = fdtol->fdl_next) { 1896 if ((fdtol->fdl_leader->p_flag & 1897 P_ADVLOCK) == 0) 1898 continue; 1899 fdtol->fdl_holdcount++; 1900 FILEDESC_UNLOCK(fdp); 1901 lf.l_whence = SEEK_SET; 1902 lf.l_start = 0; 1903 lf.l_len = 0; 1904 lf.l_type = F_UNLCK; 1905 vp = fp->f_vnode; 1906 (void) VOP_ADVLOCK(vp, 1907 (caddr_t)fdtol->fdl_leader, 1908 F_UNLCK, &lf, F_POSIX); 1909 FILEDESC_LOCK(fdp); 1910 fdtol->fdl_holdcount--; 1911 if (fdtol->fdl_holdcount == 0 && 1912 fdtol->fdl_wakeup != 0) { 1913 fdtol->fdl_wakeup = 0; 1914 wakeup(fdtol); 1915 } 1916 } 1917 FILEDESC_UNLOCK(fdp); 1918 } 1919 VFS_UNLOCK_GIANT(vfslocked); 1920 } 1921 return (fdrop(fp, td)); 1922 } 1923 1924 /* 1925 * Extract the file pointer associated with the specified descriptor for 1926 * the current user process. 1927 * 1928 * If the descriptor doesn't exist, EBADF is returned. 1929 * 1930 * If the descriptor exists but doesn't match 'flags' then 1931 * return EBADF for read attempts and EINVAL for write attempts. 1932 * 1933 * If 'hold' is set (non-zero) the file's refcount will be bumped on return. 1934 * It should be dropped with fdrop(). 1935 * If it is not set, then the refcount will not be bumped however the 1936 * thread's filedesc struct will be returned locked (for fgetsock). 1937 * 1938 * If an error occured the non-zero error is returned and *fpp is set to NULL. 1939 * Otherwise *fpp is set and zero is returned. 1940 */ 1941 static __inline int 1942 _fget(struct thread *td, int fd, struct file **fpp, int flags, int hold) 1943 { 1944 struct filedesc *fdp; 1945 struct file *fp; 1946 1947 *fpp = NULL; 1948 if (td == NULL || (fdp = td->td_proc->p_fd) == NULL) 1949 return (EBADF); 1950 FILEDESC_LOCK(fdp); 1951 if ((fp = fget_locked(fdp, fd)) == NULL || fp->f_ops == &badfileops) { 1952 FILEDESC_UNLOCK(fdp); 1953 return (EBADF); 1954 } 1955 1956 /* 1957 * Note: FREAD failure returns EBADF to maintain backwards 1958 * compatibility with what routines returned before. 1959 * 1960 * Only one flag, or 0, may be specified. 1961 */ 1962 if (flags == FREAD && (fp->f_flag & FREAD) == 0) { 1963 FILEDESC_UNLOCK(fdp); 1964 return (EBADF); 1965 } 1966 if (flags == FWRITE && (fp->f_flag & FWRITE) == 0) { 1967 FILEDESC_UNLOCK(fdp); 1968 return (EINVAL); 1969 } 1970 if (hold) { 1971 fhold(fp); 1972 FILEDESC_UNLOCK(fdp); 1973 } 1974 *fpp = fp; 1975 return (0); 1976 } 1977 1978 int 1979 fget(struct thread *td, int fd, struct file **fpp) 1980 { 1981 1982 return(_fget(td, fd, fpp, 0, 1)); 1983 } 1984 1985 int 1986 fget_read(struct thread *td, int fd, struct file **fpp) 1987 { 1988 1989 return(_fget(td, fd, fpp, FREAD, 1)); 1990 } 1991 1992 int 1993 fget_write(struct thread *td, int fd, struct file **fpp) 1994 { 1995 1996 return(_fget(td, fd, fpp, FWRITE, 1)); 1997 } 1998 1999 /* 2000 * Like fget() but loads the underlying vnode, or returns an error if 2001 * the descriptor does not represent a vnode. Note that pipes use vnodes 2002 * but never have VM objects. The returned vnode will be vref()d. 2003 * 2004 * XXX: what about the unused flags ? 2005 */ 2006 static __inline int 2007 _fgetvp(struct thread *td, int fd, struct vnode **vpp, int flags) 2008 { 2009 struct file *fp; 2010 int error; 2011 2012 *vpp = NULL; 2013 if ((error = _fget(td, fd, &fp, 0, 0)) != 0) 2014 return (error); 2015 if (fp->f_vnode == NULL) { 2016 error = EINVAL; 2017 } else { 2018 *vpp = fp->f_vnode; 2019 vref(*vpp); 2020 } 2021 FILEDESC_UNLOCK(td->td_proc->p_fd); 2022 return (error); 2023 } 2024 2025 int 2026 fgetvp(struct thread *td, int fd, struct vnode **vpp) 2027 { 2028 2029 return (_fgetvp(td, fd, vpp, 0)); 2030 } 2031 2032 int 2033 fgetvp_read(struct thread *td, int fd, struct vnode **vpp) 2034 { 2035 2036 return (_fgetvp(td, fd, vpp, FREAD)); 2037 } 2038 2039 #ifdef notyet 2040 int 2041 fgetvp_write(struct thread *td, int fd, struct vnode **vpp) 2042 { 2043 2044 return (_fgetvp(td, fd, vpp, FWRITE)); 2045 } 2046 #endif 2047 2048 /* 2049 * Like fget() but loads the underlying socket, or returns an error if 2050 * the descriptor does not represent a socket. 2051 * 2052 * We bump the ref count on the returned socket. XXX Also obtain the SX 2053 * lock in the future. 2054 */ 2055 int 2056 fgetsock(struct thread *td, int fd, struct socket **spp, u_int *fflagp) 2057 { 2058 struct file *fp; 2059 int error; 2060 2061 NET_ASSERT_GIANT(); 2062 2063 *spp = NULL; 2064 if (fflagp != NULL) 2065 *fflagp = 0; 2066 if ((error = _fget(td, fd, &fp, 0, 0)) != 0) 2067 return (error); 2068 if (fp->f_type != DTYPE_SOCKET) { 2069 error = ENOTSOCK; 2070 } else { 2071 *spp = fp->f_data; 2072 if (fflagp) 2073 *fflagp = fp->f_flag; 2074 SOCK_LOCK(*spp); 2075 soref(*spp); 2076 SOCK_UNLOCK(*spp); 2077 } 2078 FILEDESC_UNLOCK(td->td_proc->p_fd); 2079 return (error); 2080 } 2081 2082 /* 2083 * Drop the reference count on the socket and XXX release the SX lock in 2084 * the future. The last reference closes the socket. 2085 */ 2086 void 2087 fputsock(struct socket *so) 2088 { 2089 2090 NET_ASSERT_GIANT(); 2091 ACCEPT_LOCK(); 2092 SOCK_LOCK(so); 2093 sorele(so); 2094 } 2095 2096 int 2097 fdrop(struct file *fp, struct thread *td) 2098 { 2099 2100 FILE_LOCK(fp); 2101 return (fdrop_locked(fp, td)); 2102 } 2103 2104 /* 2105 * Drop reference on struct file passed in, may call closef if the 2106 * reference hits zero. 2107 * Expects struct file locked, and will unlock it. 2108 */ 2109 static int 2110 fdrop_locked(struct file *fp, struct thread *td) 2111 { 2112 int error; 2113 2114 FILE_LOCK_ASSERT(fp, MA_OWNED); 2115 2116 if (--fp->f_count > 0) { 2117 FILE_UNLOCK(fp); 2118 return (0); 2119 } 2120 /* We have the last ref so we can proceed without the file lock. */ 2121 FILE_UNLOCK(fp); 2122 if (fp->f_count < 0) 2123 panic("fdrop: count < 0"); 2124 if (fp->f_ops != &badfileops) 2125 error = fo_close(fp, td); 2126 else 2127 error = 0; 2128 2129 sx_xlock(&filelist_lock); 2130 LIST_REMOVE(fp, f_list); 2131 openfiles--; 2132 sx_xunlock(&filelist_lock); 2133 crfree(fp->f_cred); 2134 uma_zfree(file_zone, fp); 2135 2136 return (error); 2137 } 2138 2139 /* 2140 * Apply an advisory lock on a file descriptor. 2141 * 2142 * Just attempt to get a record lock of the requested type on 2143 * the entire file (l_whence = SEEK_SET, l_start = 0, l_len = 0). 2144 */ 2145 #ifndef _SYS_SYSPROTO_H_ 2146 struct flock_args { 2147 int fd; 2148 int how; 2149 }; 2150 #endif 2151 /* 2152 * MPSAFE 2153 */ 2154 /* ARGSUSED */ 2155 int 2156 flock(struct thread *td, struct flock_args *uap) 2157 { 2158 struct file *fp; 2159 struct vnode *vp; 2160 struct flock lf; 2161 int error; 2162 2163 if ((error = fget(td, uap->fd, &fp)) != 0) 2164 return (error); 2165 if (fp->f_type != DTYPE_VNODE) { 2166 fdrop(fp, td); 2167 return (EOPNOTSUPP); 2168 } 2169 2170 mtx_lock(&Giant); 2171 vp = fp->f_vnode; 2172 lf.l_whence = SEEK_SET; 2173 lf.l_start = 0; 2174 lf.l_len = 0; 2175 if (uap->how & LOCK_UN) { 2176 lf.l_type = F_UNLCK; 2177 FILE_LOCK(fp); 2178 fp->f_flag &= ~FHASLOCK; 2179 FILE_UNLOCK(fp); 2180 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, F_FLOCK); 2181 goto done2; 2182 } 2183 if (uap->how & LOCK_EX) 2184 lf.l_type = F_WRLCK; 2185 else if (uap->how & LOCK_SH) 2186 lf.l_type = F_RDLCK; 2187 else { 2188 error = EBADF; 2189 goto done2; 2190 } 2191 FILE_LOCK(fp); 2192 fp->f_flag |= FHASLOCK; 2193 FILE_UNLOCK(fp); 2194 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, 2195 (uap->how & LOCK_NB) ? F_FLOCK : F_FLOCK | F_WAIT); 2196 done2: 2197 fdrop(fp, td); 2198 mtx_unlock(&Giant); 2199 return (error); 2200 } 2201 /* 2202 * Duplicate the specified descriptor to a free descriptor. 2203 */ 2204 int 2205 dupfdopen(struct thread *td, struct filedesc *fdp, int indx, int dfd, int mode, int error) 2206 { 2207 struct file *wfp; 2208 struct file *fp; 2209 2210 /* 2211 * If the to-be-dup'd fd number is greater than the allowed number 2212 * of file descriptors, or the fd to be dup'd has already been 2213 * closed, then reject. 2214 */ 2215 FILEDESC_LOCK(fdp); 2216 if (dfd < 0 || dfd >= fdp->fd_nfiles || 2217 (wfp = fdp->fd_ofiles[dfd]) == NULL) { 2218 FILEDESC_UNLOCK(fdp); 2219 return (EBADF); 2220 } 2221 2222 /* 2223 * There are two cases of interest here. 2224 * 2225 * For ENODEV simply dup (dfd) to file descriptor 2226 * (indx) and return. 2227 * 2228 * For ENXIO steal away the file structure from (dfd) and 2229 * store it in (indx). (dfd) is effectively closed by 2230 * this operation. 2231 * 2232 * Any other error code is just returned. 2233 */ 2234 switch (error) { 2235 case ENODEV: 2236 /* 2237 * Check that the mode the file is being opened for is a 2238 * subset of the mode of the existing descriptor. 2239 */ 2240 FILE_LOCK(wfp); 2241 if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag) { 2242 FILE_UNLOCK(wfp); 2243 FILEDESC_UNLOCK(fdp); 2244 return (EACCES); 2245 } 2246 fp = fdp->fd_ofiles[indx]; 2247 fdp->fd_ofiles[indx] = wfp; 2248 fdp->fd_ofileflags[indx] = fdp->fd_ofileflags[dfd]; 2249 if (fp == NULL) 2250 fdused(fdp, indx); 2251 fhold_locked(wfp); 2252 FILE_UNLOCK(wfp); 2253 FILEDESC_UNLOCK(fdp); 2254 if (fp != NULL) { 2255 /* 2256 * We now own the reference to fp that the ofiles[] 2257 * array used to own. Release it. 2258 */ 2259 FILE_LOCK(fp); 2260 fdrop_locked(fp, td); 2261 } 2262 return (0); 2263 2264 case ENXIO: 2265 /* 2266 * Steal away the file pointer from dfd and stuff it into indx. 2267 */ 2268 fp = fdp->fd_ofiles[indx]; 2269 fdp->fd_ofiles[indx] = fdp->fd_ofiles[dfd]; 2270 fdp->fd_ofiles[dfd] = NULL; 2271 fdp->fd_ofileflags[indx] = fdp->fd_ofileflags[dfd]; 2272 fdp->fd_ofileflags[dfd] = 0; 2273 fdunused(fdp, dfd); 2274 if (fp == NULL) 2275 fdused(fdp, indx); 2276 if (fp != NULL) 2277 FILE_LOCK(fp); 2278 2279 /* 2280 * We now own the reference to fp that the ofiles[] array 2281 * used to own. Release it. 2282 */ 2283 if (fp != NULL) 2284 fdrop_locked(fp, td); 2285 2286 FILEDESC_UNLOCK(fdp); 2287 2288 return (0); 2289 2290 default: 2291 FILEDESC_UNLOCK(fdp); 2292 return (error); 2293 } 2294 /* NOTREACHED */ 2295 } 2296 2297 /* 2298 * Scan all active processes to see if any of them have a current 2299 * or root directory of `olddp'. If so, replace them with the new 2300 * mount point. 2301 */ 2302 void 2303 mountcheckdirs(struct vnode *olddp, struct vnode *newdp) 2304 { 2305 struct filedesc *fdp; 2306 struct proc *p; 2307 int nrele; 2308 2309 if (vrefcnt(olddp) == 1) 2310 return; 2311 sx_slock(&allproc_lock); 2312 LIST_FOREACH(p, &allproc, p_list) { 2313 fdp = fdhold(p); 2314 if (fdp == NULL) 2315 continue; 2316 nrele = 0; 2317 FILEDESC_LOCK_FAST(fdp); 2318 if (fdp->fd_cdir == olddp) { 2319 vref(newdp); 2320 fdp->fd_cdir = newdp; 2321 nrele++; 2322 } 2323 if (fdp->fd_rdir == olddp) { 2324 vref(newdp); 2325 fdp->fd_rdir = newdp; 2326 nrele++; 2327 } 2328 FILEDESC_UNLOCK_FAST(fdp); 2329 fddrop(fdp); 2330 while (nrele--) 2331 vrele(olddp); 2332 } 2333 sx_sunlock(&allproc_lock); 2334 if (rootvnode == olddp) { 2335 vrele(rootvnode); 2336 vref(newdp); 2337 rootvnode = newdp; 2338 } 2339 } 2340 2341 struct filedesc_to_leader * 2342 filedesc_to_leader_alloc(struct filedesc_to_leader *old, struct filedesc *fdp, struct proc *leader) 2343 { 2344 struct filedesc_to_leader *fdtol; 2345 2346 MALLOC(fdtol, struct filedesc_to_leader *, 2347 sizeof(struct filedesc_to_leader), 2348 M_FILEDESC_TO_LEADER, 2349 M_WAITOK); 2350 fdtol->fdl_refcount = 1; 2351 fdtol->fdl_holdcount = 0; 2352 fdtol->fdl_wakeup = 0; 2353 fdtol->fdl_leader = leader; 2354 if (old != NULL) { 2355 FILEDESC_LOCK(fdp); 2356 fdtol->fdl_next = old->fdl_next; 2357 fdtol->fdl_prev = old; 2358 old->fdl_next = fdtol; 2359 fdtol->fdl_next->fdl_prev = fdtol; 2360 FILEDESC_UNLOCK(fdp); 2361 } else { 2362 fdtol->fdl_next = fdtol; 2363 fdtol->fdl_prev = fdtol; 2364 } 2365 return (fdtol); 2366 } 2367 2368 /* 2369 * Get file structures. 2370 */ 2371 static int 2372 sysctl_kern_file(SYSCTL_HANDLER_ARGS) 2373 { 2374 struct xfile xf; 2375 struct filedesc *fdp; 2376 struct file *fp; 2377 struct proc *p; 2378 int error, n; 2379 2380 /* 2381 * Note: because the number of file descriptors is calculated 2382 * in different ways for sizing vs returning the data, 2383 * there is information leakage from the first loop. However, 2384 * it is of a similar order of magnitude to the leakage from 2385 * global system statistics such as kern.openfiles. 2386 */ 2387 error = sysctl_wire_old_buffer(req, 0); 2388 if (error != 0) 2389 return (error); 2390 if (req->oldptr == NULL) { 2391 n = 16; /* A slight overestimate. */ 2392 sx_slock(&filelist_lock); 2393 LIST_FOREACH(fp, &filehead, f_list) { 2394 /* 2395 * We should grab the lock, but this is an 2396 * estimate, so does it really matter? 2397 */ 2398 /* mtx_lock(fp->f_mtxp); */ 2399 n += fp->f_count; 2400 /* mtx_unlock(f->f_mtxp); */ 2401 } 2402 sx_sunlock(&filelist_lock); 2403 return (SYSCTL_OUT(req, 0, n * sizeof(xf))); 2404 } 2405 error = 0; 2406 bzero(&xf, sizeof(xf)); 2407 xf.xf_size = sizeof(xf); 2408 sx_slock(&allproc_lock); 2409 LIST_FOREACH(p, &allproc, p_list) { 2410 if (p->p_state == PRS_NEW) 2411 continue; 2412 PROC_LOCK(p); 2413 if (p_cansee(req->td, p) != 0) { 2414 PROC_UNLOCK(p); 2415 continue; 2416 } 2417 xf.xf_pid = p->p_pid; 2418 xf.xf_uid = p->p_ucred->cr_uid; 2419 PROC_UNLOCK(p); 2420 fdp = fdhold(p); 2421 if (fdp == NULL) 2422 continue; 2423 FILEDESC_LOCK_FAST(fdp); 2424 for (n = 0; fdp->fd_refcnt > 0 && n < fdp->fd_nfiles; ++n) { 2425 if ((fp = fdp->fd_ofiles[n]) == NULL) 2426 continue; 2427 xf.xf_fd = n; 2428 xf.xf_file = fp; 2429 xf.xf_data = fp->f_data; 2430 xf.xf_vnode = fp->f_vnode; 2431 xf.xf_type = fp->f_type; 2432 xf.xf_count = fp->f_count; 2433 xf.xf_msgcount = fp->f_msgcount; 2434 xf.xf_offset = fp->f_offset; 2435 xf.xf_flag = fp->f_flag; 2436 error = SYSCTL_OUT(req, &xf, sizeof(xf)); 2437 if (error) 2438 break; 2439 } 2440 FILEDESC_UNLOCK_FAST(fdp); 2441 fddrop(fdp); 2442 if (error) 2443 break; 2444 } 2445 sx_sunlock(&allproc_lock); 2446 return (error); 2447 } 2448 2449 SYSCTL_PROC(_kern, KERN_FILE, file, CTLTYPE_OPAQUE|CTLFLAG_RD, 2450 0, 0, sysctl_kern_file, "S,xfile", "Entire file table"); 2451 2452 SYSCTL_INT(_kern, KERN_MAXFILESPERPROC, maxfilesperproc, CTLFLAG_RW, 2453 &maxfilesperproc, 0, "Maximum files allowed open per process"); 2454 2455 SYSCTL_INT(_kern, KERN_MAXFILES, maxfiles, CTLFLAG_RW, 2456 &maxfiles, 0, "Maximum number of files"); 2457 2458 SYSCTL_INT(_kern, OID_AUTO, openfiles, CTLFLAG_RD, 2459 &openfiles, 0, "System-wide number of open files"); 2460 2461 /* ARGSUSED*/ 2462 static void 2463 filelistinit(void *dummy) 2464 { 2465 2466 file_zone = uma_zcreate("Files", sizeof(struct file), NULL, NULL, 2467 NULL, NULL, UMA_ALIGN_PTR, 0); 2468 sx_init(&filelist_lock, "filelist lock"); 2469 mtx_init(&sigio_lock, "sigio lock", NULL, MTX_DEF); 2470 mtx_init(&fdesc_mtx, "fdesc", NULL, MTX_DEF); 2471 } 2472 SYSINIT(select, SI_SUB_LOCK, SI_ORDER_FIRST, filelistinit, NULL) 2473 2474 /*-------------------------------------------------------------------*/ 2475 2476 static int 2477 badfo_readwrite(struct file *fp, struct uio *uio, struct ucred *active_cred, int flags, struct thread *td) 2478 { 2479 2480 return (EBADF); 2481 } 2482 2483 static int 2484 badfo_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred, struct thread *td) 2485 { 2486 2487 return (EBADF); 2488 } 2489 2490 static int 2491 badfo_poll(struct file *fp, int events, struct ucred *active_cred, struct thread *td) 2492 { 2493 2494 return (0); 2495 } 2496 2497 static int 2498 badfo_kqfilter(struct file *fp, struct knote *kn) 2499 { 2500 2501 return (0); 2502 } 2503 2504 static int 2505 badfo_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, struct thread *td) 2506 { 2507 2508 return (EBADF); 2509 } 2510 2511 static int 2512 badfo_close(struct file *fp, struct thread *td) 2513 { 2514 2515 return (EBADF); 2516 } 2517 2518 struct fileops badfileops = { 2519 .fo_read = badfo_readwrite, 2520 .fo_write = badfo_readwrite, 2521 .fo_ioctl = badfo_ioctl, 2522 .fo_poll = badfo_poll, 2523 .fo_kqfilter = badfo_kqfilter, 2524 .fo_stat = badfo_stat, 2525 .fo_close = badfo_close, 2526 }; 2527 2528 2529 /*-------------------------------------------------------------------*/ 2530 2531 /* 2532 * File Descriptor pseudo-device driver (/dev/fd/). 2533 * 2534 * Opening minor device N dup()s the file (if any) connected to file 2535 * descriptor N belonging to the calling process. Note that this driver 2536 * consists of only the ``open()'' routine, because all subsequent 2537 * references to this file will be direct to the other driver. 2538 * 2539 * XXX: we could give this one a cloning event handler if necessary. 2540 */ 2541 2542 /* ARGSUSED */ 2543 static int 2544 fdopen(struct cdev *dev, int mode, int type, struct thread *td) 2545 { 2546 2547 /* 2548 * XXX Kludge: set curthread->td_dupfd to contain the value of the 2549 * the file descriptor being sought for duplication. The error 2550 * return ensures that the vnode for this device will be released 2551 * by vn_open. Open will detect this special error and take the 2552 * actions in dupfdopen below. Other callers of vn_open or VOP_OPEN 2553 * will simply report the error. 2554 */ 2555 td->td_dupfd = dev2unit(dev); 2556 return (ENODEV); 2557 } 2558 2559 static struct cdevsw fildesc_cdevsw = { 2560 .d_version = D_VERSION, 2561 .d_flags = D_NEEDGIANT, 2562 .d_open = fdopen, 2563 .d_name = "FD", 2564 }; 2565 2566 static void 2567 fildesc_drvinit(void *unused) 2568 { 2569 struct cdev *dev; 2570 2571 dev = make_dev(&fildesc_cdevsw, 0, UID_ROOT, GID_WHEEL, 0666, "fd/0"); 2572 make_dev_alias(dev, "stdin"); 2573 dev = make_dev(&fildesc_cdevsw, 1, UID_ROOT, GID_WHEEL, 0666, "fd/1"); 2574 make_dev_alias(dev, "stdout"); 2575 dev = make_dev(&fildesc_cdevsw, 2, UID_ROOT, GID_WHEEL, 0666, "fd/2"); 2576 make_dev_alias(dev, "stderr"); 2577 } 2578 2579 SYSINIT(fildescdev, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, fildesc_drvinit, NULL)
Cache object: 49d3e58a6665f7a123ae0b083fbb7804
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