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 int fd = 0; 198 199 error = kern_dup(DUP_FIXED, uap->from, uap->to, &fd); 200 uap->sysmsg_fds[0] = fd; 201 202 return (error); 203 } 204 205 /* 206 * Duplicate a file descriptor. 207 * 208 * MPSAFE 209 */ 210 int 211 sys_dup(struct dup_args *uap) 212 { 213 int error; 214 int fd = 0; 215 216 error = kern_dup(DUP_VARIABLE, uap->fd, 0, &fd); 217 uap->sysmsg_fds[0] = fd; 218 219 return (error); 220 } 221 222 /* 223 * MPALMOSTSAFE - acquires mplock for fp operations 224 */ 225 int 226 kern_fcntl(int fd, int cmd, union fcntl_dat *dat, struct ucred *cred) 227 { 228 struct thread *td = curthread; 229 struct proc *p = td->td_proc; 230 struct file *fp; 231 struct vnode *vp; 232 u_int newmin; 233 u_int oflags; 234 u_int nflags; 235 int tmp, error, flg = F_POSIX; 236 237 KKASSERT(p); 238 239 /* 240 * Operations on file descriptors that do not require a file pointer. 241 */ 242 switch (cmd) { 243 case F_GETFD: 244 error = fgetfdflags(p->p_fd, fd, &tmp); 245 if (error == 0) 246 dat->fc_cloexec = (tmp & UF_EXCLOSE) ? FD_CLOEXEC : 0; 247 return (error); 248 249 case F_SETFD: 250 if (dat->fc_cloexec & FD_CLOEXEC) 251 error = fsetfdflags(p->p_fd, fd, UF_EXCLOSE); 252 else 253 error = fclrfdflags(p->p_fd, fd, UF_EXCLOSE); 254 return (error); 255 case F_DUPFD: 256 newmin = dat->fc_fd; 257 error = kern_dup(DUP_VARIABLE, fd, newmin, &dat->fc_fd); 258 return (error); 259 default: 260 break; 261 } 262 263 /* 264 * Operations on file pointers 265 */ 266 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL) 267 return (EBADF); 268 269 get_mplock(); 270 switch (cmd) { 271 case F_GETFL: 272 dat->fc_flags = OFLAGS(fp->f_flag); 273 error = 0; 274 break; 275 276 case F_SETFL: 277 oflags = fp->f_flag; 278 nflags = FFLAGS(dat->fc_flags & ~O_ACCMODE) & FCNTLFLAGS; 279 nflags |= oflags & ~FCNTLFLAGS; 280 281 error = 0; 282 if (((nflags ^ oflags) & O_APPEND) && (oflags & FAPPENDONLY)) 283 error = EINVAL; 284 if (error == 0 && ((nflags ^ oflags) & FASYNC)) { 285 tmp = nflags & FASYNC; 286 error = fo_ioctl(fp, FIOASYNC, (caddr_t)&tmp, cred); 287 } 288 if (error == 0) 289 fp->f_flag = nflags; 290 break; 291 292 case F_GETOWN: 293 error = fo_ioctl(fp, FIOGETOWN, (caddr_t)&dat->fc_owner, cred); 294 break; 295 296 case F_SETOWN: 297 error = fo_ioctl(fp, FIOSETOWN, (caddr_t)&dat->fc_owner, cred); 298 break; 299 300 case F_SETLKW: 301 flg |= F_WAIT; 302 /* Fall into F_SETLK */ 303 304 case F_SETLK: 305 if (fp->f_type != DTYPE_VNODE) { 306 error = EBADF; 307 break; 308 } 309 vp = (struct vnode *)fp->f_data; 310 311 /* 312 * copyin/lockop may block 313 */ 314 if (dat->fc_flock.l_whence == SEEK_CUR) 315 dat->fc_flock.l_start += fp->f_offset; 316 317 switch (dat->fc_flock.l_type) { 318 case F_RDLCK: 319 if ((fp->f_flag & FREAD) == 0) { 320 error = EBADF; 321 break; 322 } 323 p->p_leader->p_flag |= P_ADVLOCK; 324 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK, 325 &dat->fc_flock, flg); 326 break; 327 case F_WRLCK: 328 if ((fp->f_flag & FWRITE) == 0) { 329 error = EBADF; 330 break; 331 } 332 p->p_leader->p_flag |= P_ADVLOCK; 333 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK, 334 &dat->fc_flock, flg); 335 break; 336 case F_UNLCK: 337 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK, 338 &dat->fc_flock, F_POSIX); 339 break; 340 default: 341 error = EINVAL; 342 break; 343 } 344 345 /* 346 * It is possible to race a close() on the descriptor while 347 * we were blocked getting the lock. If this occurs the 348 * close might not have caught the lock. 349 */ 350 if (checkfpclosed(p->p_fd, fd, fp)) { 351 dat->fc_flock.l_whence = SEEK_SET; 352 dat->fc_flock.l_start = 0; 353 dat->fc_flock.l_len = 0; 354 dat->fc_flock.l_type = F_UNLCK; 355 (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader, 356 F_UNLCK, &dat->fc_flock, F_POSIX); 357 } 358 break; 359 360 case F_GETLK: 361 if (fp->f_type != DTYPE_VNODE) { 362 error = EBADF; 363 break; 364 } 365 vp = (struct vnode *)fp->f_data; 366 /* 367 * copyin/lockop may block 368 */ 369 if (dat->fc_flock.l_type != F_RDLCK && 370 dat->fc_flock.l_type != F_WRLCK && 371 dat->fc_flock.l_type != F_UNLCK) { 372 error = EINVAL; 373 break; 374 } 375 if (dat->fc_flock.l_whence == SEEK_CUR) 376 dat->fc_flock.l_start += fp->f_offset; 377 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_GETLK, 378 &dat->fc_flock, F_POSIX); 379 break; 380 default: 381 error = EINVAL; 382 break; 383 } 384 rel_mplock(); 385 386 fdrop(fp); 387 return (error); 388 } 389 390 /* 391 * The file control system call. 392 * 393 * MPSAFE 394 */ 395 int 396 sys_fcntl(struct fcntl_args *uap) 397 { 398 union fcntl_dat dat; 399 int error; 400 401 switch (uap->cmd) { 402 case F_DUPFD: 403 dat.fc_fd = uap->arg; 404 break; 405 case F_SETFD: 406 dat.fc_cloexec = uap->arg; 407 break; 408 case F_SETFL: 409 dat.fc_flags = uap->arg; 410 break; 411 case F_SETOWN: 412 dat.fc_owner = uap->arg; 413 break; 414 case F_SETLKW: 415 case F_SETLK: 416 case F_GETLK: 417 error = copyin((caddr_t)uap->arg, &dat.fc_flock, 418 sizeof(struct flock)); 419 if (error) 420 return (error); 421 break; 422 } 423 424 error = kern_fcntl(uap->fd, uap->cmd, &dat, curproc->p_ucred); 425 426 if (error == 0) { 427 switch (uap->cmd) { 428 case F_DUPFD: 429 uap->sysmsg_result = dat.fc_fd; 430 break; 431 case F_GETFD: 432 uap->sysmsg_result = dat.fc_cloexec; 433 break; 434 case F_GETFL: 435 uap->sysmsg_result = dat.fc_flags; 436 break; 437 case F_GETOWN: 438 uap->sysmsg_result = dat.fc_owner; 439 case F_GETLK: 440 error = copyout(&dat.fc_flock, (caddr_t)uap->arg, 441 sizeof(struct flock)); 442 break; 443 } 444 } 445 446 return (error); 447 } 448 449 /* 450 * Common code for dup, dup2, and fcntl(F_DUPFD). 451 * 452 * The type flag can be either DUP_FIXED or DUP_VARIABLE. DUP_FIXED tells 453 * kern_dup() to destructively dup over an existing file descriptor if new 454 * is already open. DUP_VARIABLE tells kern_dup() to find the lowest 455 * unused file descriptor that is greater than or equal to new. 456 * 457 * MPSAFE 458 */ 459 int 460 kern_dup(enum dup_type type, int old, int new, int *res) 461 { 462 struct thread *td = curthread; 463 struct proc *p = td->td_proc; 464 struct filedesc *fdp = p->p_fd; 465 struct file *fp; 466 struct file *delfp; 467 int oldflags; 468 int holdleaders; 469 int error, newfd; 470 471 /* 472 * Verify that we have a valid descriptor to dup from and 473 * possibly to dup to. 474 */ 475 retry: 476 spin_lock_wr(&fdp->fd_spin); 477 if (new < 0 || new > p->p_rlimit[RLIMIT_NOFILE].rlim_cur || 478 new >= maxfilesperproc) { 479 spin_unlock_wr(&fdp->fd_spin); 480 return (EINVAL); 481 } 482 if ((unsigned)old >= fdp->fd_nfiles || fdp->fd_files[old].fp == NULL) { 483 spin_unlock_wr(&fdp->fd_spin); 484 return (EBADF); 485 } 486 if (type == DUP_FIXED && old == new) { 487 *res = new; 488 spin_unlock_wr(&fdp->fd_spin); 489 return (0); 490 } 491 fp = fdp->fd_files[old].fp; 492 oldflags = fdp->fd_files[old].fileflags; 493 fhold(fp); /* MPSAFE - can be called with a spinlock held */ 494 495 /* 496 * Allocate a new descriptor if DUP_VARIABLE, or expand the table 497 * if the requested descriptor is beyond the current table size. 498 * 499 * This can block. Retry if the source descriptor no longer matches 500 * or if our expectation in the expansion case races. 501 * 502 * If we are not expanding or allocating a new decriptor, then reset 503 * the target descriptor to a reserved state so we have a uniform 504 * setup for the next code block. 505 */ 506 if (type == DUP_VARIABLE || new >= fdp->fd_nfiles) { 507 spin_unlock_wr(&fdp->fd_spin); 508 error = fdalloc(p, new, &newfd); 509 spin_lock_wr(&fdp->fd_spin); 510 if (error) { 511 spin_unlock_wr(&fdp->fd_spin); 512 fdrop(fp); 513 return (error); 514 } 515 /* 516 * Check for ripout 517 */ 518 if (old >= fdp->fd_nfiles || fdp->fd_files[old].fp != fp) { 519 fsetfd_locked(fdp, NULL, newfd); 520 spin_unlock_wr(&fdp->fd_spin); 521 fdrop(fp); 522 goto retry; 523 } 524 /* 525 * Check for expansion race 526 */ 527 if (type != DUP_VARIABLE && new != newfd) { 528 fsetfd_locked(fdp, NULL, newfd); 529 spin_unlock_wr(&fdp->fd_spin); 530 fdrop(fp); 531 goto retry; 532 } 533 /* 534 * Check for ripout, newfd reused old (this case probably 535 * can't occur). 536 */ 537 if (old == newfd) { 538 fsetfd_locked(fdp, NULL, newfd); 539 spin_unlock_wr(&fdp->fd_spin); 540 fdrop(fp); 541 goto retry; 542 } 543 new = newfd; 544 delfp = NULL; 545 } else { 546 if (fdp->fd_files[new].reserved) { 547 spin_unlock_wr(&fdp->fd_spin); 548 fdrop(fp); 549 kprintf("Warning: dup(): target descriptor %d is reserved, waiting for it to be resolved\n", new); 550 tsleep(fdp, 0, "fdres", hz); 551 goto retry; 552 } 553 554 /* 555 * If the target descriptor was never allocated we have 556 * to allocate it. If it was we have to clean out the 557 * old descriptor. delfp inherits the ref from the 558 * descriptor table. 559 */ 560 delfp = fdp->fd_files[new].fp; 561 fdp->fd_files[new].fp = NULL; 562 fdp->fd_files[new].reserved = 1; 563 if (delfp == NULL) { 564 fdreserve_locked(fdp, new, 1); 565 if (new > fdp->fd_lastfile) 566 fdp->fd_lastfile = new; 567 } 568 569 } 570 571 /* 572 * NOTE: still holding an exclusive spinlock 573 */ 574 575 /* 576 * If a descriptor is being overwritten we may hve to tell 577 * fdfree() to sleep to ensure that all relevant process 578 * leaders can be traversed in closef(). 579 */ 580 if (delfp != NULL && p->p_fdtol != NULL) { 581 fdp->fd_holdleaderscount++; 582 holdleaders = 1; 583 } else { 584 holdleaders = 0; 585 } 586 KASSERT(delfp == NULL || type == DUP_FIXED, 587 ("dup() picked an open file")); 588 589 /* 590 * Duplicate the source descriptor, update lastfile. If the new 591 * descriptor was not allocated and we aren't replacing an existing 592 * descriptor we have to mark the descriptor as being in use. 593 * 594 * The fd_files[] array inherits fp's hold reference. 595 */ 596 fsetfd_locked(fdp, fp, new); 597 fdp->fd_files[new].fileflags = oldflags & ~UF_EXCLOSE; 598 spin_unlock_wr(&fdp->fd_spin); 599 fdrop(fp); 600 *res = new; 601 602 /* 603 * If we dup'd over a valid file, we now own the reference to it 604 * and must dispose of it using closef() semantics (as if a 605 * close() were performed on it). 606 */ 607 if (delfp) { 608 closef(delfp, p); 609 if (holdleaders) { 610 spin_lock_wr(&fdp->fd_spin); 611 fdp->fd_holdleaderscount--; 612 if (fdp->fd_holdleaderscount == 0 && 613 fdp->fd_holdleaderswakeup != 0) { 614 fdp->fd_holdleaderswakeup = 0; 615 spin_unlock_wr(&fdp->fd_spin); 616 wakeup(&fdp->fd_holdleaderscount); 617 } else { 618 spin_unlock_wr(&fdp->fd_spin); 619 } 620 } 621 } 622 return (0); 623 } 624 625 /* 626 * If sigio is on the list associated with a process or process group, 627 * disable signalling from the device, remove sigio from the list and 628 * free sigio. 629 */ 630 void 631 funsetown(struct sigio *sigio) 632 { 633 if (sigio == NULL) 634 return; 635 crit_enter(); 636 *(sigio->sio_myref) = NULL; 637 crit_exit(); 638 if (sigio->sio_pgid < 0) { 639 SLIST_REMOVE(&sigio->sio_pgrp->pg_sigiolst, sigio, 640 sigio, sio_pgsigio); 641 } else /* if ((*sigiop)->sio_pgid > 0) */ { 642 SLIST_REMOVE(&sigio->sio_proc->p_sigiolst, sigio, 643 sigio, sio_pgsigio); 644 } 645 crfree(sigio->sio_ucred); 646 kfree(sigio, M_SIGIO); 647 } 648 649 /* Free a list of sigio structures. */ 650 void 651 funsetownlst(struct sigiolst *sigiolst) 652 { 653 struct sigio *sigio; 654 655 while ((sigio = SLIST_FIRST(sigiolst)) != NULL) 656 funsetown(sigio); 657 } 658 659 /* 660 * This is common code for FIOSETOWN ioctl called by fcntl(fd, F_SETOWN, arg). 661 * 662 * After permission checking, add a sigio structure to the sigio list for 663 * the process or process group. 664 */ 665 int 666 fsetown(pid_t pgid, struct sigio **sigiop) 667 { 668 struct proc *proc; 669 struct pgrp *pgrp; 670 struct sigio *sigio; 671 672 if (pgid == 0) { 673 funsetown(*sigiop); 674 return (0); 675 } 676 if (pgid > 0) { 677 proc = pfind(pgid); 678 if (proc == NULL) 679 return (ESRCH); 680 681 /* 682 * Policy - Don't allow a process to FSETOWN a process 683 * in another session. 684 * 685 * Remove this test to allow maximum flexibility or 686 * restrict FSETOWN to the current process or process 687 * group for maximum safety. 688 */ 689 if (proc->p_session != curproc->p_session) 690 return (EPERM); 691 692 pgrp = NULL; 693 } else /* if (pgid < 0) */ { 694 pgrp = pgfind(-pgid); 695 if (pgrp == NULL) 696 return (ESRCH); 697 698 /* 699 * Policy - Don't allow a process to FSETOWN a process 700 * in another session. 701 * 702 * Remove this test to allow maximum flexibility or 703 * restrict FSETOWN to the current process or process 704 * group for maximum safety. 705 */ 706 if (pgrp->pg_session != curproc->p_session) 707 return (EPERM); 708 709 proc = NULL; 710 } 711 funsetown(*sigiop); 712 sigio = kmalloc(sizeof(struct sigio), M_SIGIO, M_WAITOK); 713 if (pgid > 0) { 714 SLIST_INSERT_HEAD(&proc->p_sigiolst, sigio, sio_pgsigio); 715 sigio->sio_proc = proc; 716 } else { 717 SLIST_INSERT_HEAD(&pgrp->pg_sigiolst, sigio, sio_pgsigio); 718 sigio->sio_pgrp = pgrp; 719 } 720 sigio->sio_pgid = pgid; 721 sigio->sio_ucred = crhold(curproc->p_ucred); 722 /* It would be convenient if p_ruid was in ucred. */ 723 sigio->sio_ruid = curproc->p_ucred->cr_ruid; 724 sigio->sio_myref = sigiop; 725 crit_enter(); 726 *sigiop = sigio; 727 crit_exit(); 728 return (0); 729 } 730 731 /* 732 * This is common code for FIOGETOWN ioctl called by fcntl(fd, F_GETOWN, arg). 733 */ 734 pid_t 735 fgetown(struct sigio *sigio) 736 { 737 return (sigio != NULL ? sigio->sio_pgid : 0); 738 } 739 740 /* 741 * Close many file descriptors. 742 * 743 * MPSAFE 744 */ 745 int 746 sys_closefrom(struct closefrom_args *uap) 747 { 748 return(kern_closefrom(uap->fd)); 749 } 750 751 /* 752 * Close all file descriptors greater then or equal to fd 753 * 754 * MPSAFE 755 */ 756 int 757 kern_closefrom(int fd) 758 { 759 struct thread *td = curthread; 760 struct proc *p = td->td_proc; 761 struct filedesc *fdp; 762 763 KKASSERT(p); 764 fdp = p->p_fd; 765 766 if (fd < 0) 767 return (EINVAL); 768 769 /* 770 * NOTE: This function will skip unassociated descriptors and 771 * reserved descriptors that have not yet been assigned. 772 * fd_lastfile can change as a side effect of kern_close(). 773 */ 774 spin_lock_wr(&fdp->fd_spin); 775 while (fd <= fdp->fd_lastfile) { 776 if (fdp->fd_files[fd].fp != NULL) { 777 spin_unlock_wr(&fdp->fd_spin); 778 /* ok if this races another close */ 779 if (kern_close(fd) == EINTR) 780 return (EINTR); 781 spin_lock_wr(&fdp->fd_spin); 782 } 783 ++fd; 784 } 785 spin_unlock_wr(&fdp->fd_spin); 786 return (0); 787 } 788 789 /* 790 * Close a file descriptor. 791 * 792 * MPSAFE 793 */ 794 int 795 sys_close(struct close_args *uap) 796 { 797 return(kern_close(uap->fd)); 798 } 799 800 /* 801 * MPALMOSTSAFE - acquires mplock around knote_fdclose() calls 802 */ 803 int 804 kern_close(int fd) 805 { 806 struct thread *td = curthread; 807 struct proc *p = td->td_proc; 808 struct filedesc *fdp; 809 struct file *fp; 810 int error; 811 int holdleaders; 812 813 KKASSERT(p); 814 fdp = p->p_fd; 815 816 spin_lock_wr(&fdp->fd_spin); 817 if ((fp = funsetfd_locked(fdp, fd)) == NULL) { 818 spin_unlock_wr(&fdp->fd_spin); 819 return (EBADF); 820 } 821 holdleaders = 0; 822 if (p->p_fdtol != NULL) { 823 /* 824 * Ask fdfree() to sleep to ensure that all relevant 825 * process leaders can be traversed in closef(). 826 */ 827 fdp->fd_holdleaderscount++; 828 holdleaders = 1; 829 } 830 831 /* 832 * we now hold the fp reference that used to be owned by the descriptor 833 * array. 834 */ 835 spin_unlock_wr(&fdp->fd_spin); 836 if (fd < fdp->fd_knlistsize) { 837 get_mplock(); 838 if (fd < fdp->fd_knlistsize) 839 knote_fdclose(p, fd); 840 rel_mplock(); 841 } 842 error = closef(fp, p); 843 if (holdleaders) { 844 spin_lock_wr(&fdp->fd_spin); 845 fdp->fd_holdleaderscount--; 846 if (fdp->fd_holdleaderscount == 0 && 847 fdp->fd_holdleaderswakeup != 0) { 848 fdp->fd_holdleaderswakeup = 0; 849 spin_unlock_wr(&fdp->fd_spin); 850 wakeup(&fdp->fd_holdleaderscount); 851 } else { 852 spin_unlock_wr(&fdp->fd_spin); 853 } 854 } 855 return (error); 856 } 857 858 /* 859 * shutdown_args(int fd, int how) 860 */ 861 int 862 kern_shutdown(int fd, int how) 863 { 864 struct thread *td = curthread; 865 struct proc *p = td->td_proc; 866 struct file *fp; 867 int error; 868 869 KKASSERT(p); 870 871 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL) 872 return (EBADF); 873 error = fo_shutdown(fp, how); 874 fdrop(fp); 875 876 return (error); 877 } 878 879 int 880 sys_shutdown(struct shutdown_args *uap) 881 { 882 int error; 883 884 error = kern_shutdown(uap->s, uap->how); 885 886 return (error); 887 } 888 889 int 890 kern_fstat(int fd, struct stat *ub) 891 { 892 struct thread *td = curthread; 893 struct proc *p = td->td_proc; 894 struct file *fp; 895 int error; 896 897 KKASSERT(p); 898 899 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL) 900 return (EBADF); 901 error = fo_stat(fp, ub, p->p_ucred); 902 fdrop(fp); 903 904 return (error); 905 } 906 907 /* 908 * Return status information about a file descriptor. 909 */ 910 int 911 sys_fstat(struct fstat_args *uap) 912 { 913 struct stat st; 914 int error; 915 916 error = kern_fstat(uap->fd, &st); 917 918 if (error == 0) 919 error = copyout(&st, uap->sb, sizeof(st)); 920 return (error); 921 } 922 923 /* 924 * Return pathconf information about a file descriptor. 925 */ 926 /* ARGSUSED */ 927 int 928 sys_fpathconf(struct fpathconf_args *uap) 929 { 930 struct thread *td = curthread; 931 struct proc *p = td->td_proc; 932 struct file *fp; 933 struct vnode *vp; 934 int error = 0; 935 936 KKASSERT(p); 937 938 if ((fp = holdfp(p->p_fd, uap->fd, -1)) == NULL) 939 return (EBADF); 940 941 switch (fp->f_type) { 942 case DTYPE_PIPE: 943 case DTYPE_SOCKET: 944 if (uap->name != _PC_PIPE_BUF) { 945 error = EINVAL; 946 } else { 947 uap->sysmsg_result = PIPE_BUF; 948 error = 0; 949 } 950 break; 951 case DTYPE_FIFO: 952 case DTYPE_VNODE: 953 vp = (struct vnode *)fp->f_data; 954 error = VOP_PATHCONF(vp, uap->name, uap->sysmsg_fds); 955 break; 956 default: 957 error = EOPNOTSUPP; 958 break; 959 } 960 fdrop(fp); 961 return(error); 962 } 963 964 static int fdexpand; 965 SYSCTL_INT(_debug, OID_AUTO, fdexpand, CTLFLAG_RD, &fdexpand, 0, ""); 966 967 /* 968 * Grow the file table so it can hold through descriptor (want). 969 * 970 * The fdp's spinlock must be held exclusively on entry and may be held 971 * exclusively on return. The spinlock may be cycled by the routine. 972 * 973 * MPSAFE 974 */ 975 static void 976 fdgrow_locked(struct filedesc *fdp, int want) 977 { 978 struct fdnode *newfiles; 979 struct fdnode *oldfiles; 980 int nf, extra; 981 982 nf = fdp->fd_nfiles; 983 do { 984 /* nf has to be of the form 2^n - 1 */ 985 nf = 2 * nf + 1; 986 } while (nf <= want); 987 988 spin_unlock_wr(&fdp->fd_spin); 989 newfiles = kmalloc(nf * sizeof(struct fdnode), M_FILEDESC, M_WAITOK); 990 spin_lock_wr(&fdp->fd_spin); 991 992 /* 993 * We could have raced another extend while we were not holding 994 * the spinlock. 995 */ 996 if (fdp->fd_nfiles >= nf) { 997 spin_unlock_wr(&fdp->fd_spin); 998 kfree(newfiles, M_FILEDESC); 999 spin_lock_wr(&fdp->fd_spin); 1000 return; 1001 } 1002 /* 1003 * Copy the existing ofile and ofileflags arrays 1004 * and zero the new portion of each array. 1005 */ 1006 extra = nf - fdp->fd_nfiles; 1007 bcopy(fdp->fd_files, newfiles, fdp->fd_nfiles * sizeof(struct fdnode)); 1008 bzero(&newfiles[fdp->fd_nfiles], extra * sizeof(struct fdnode)); 1009 1010 oldfiles = fdp->fd_files; 1011 fdp->fd_files = newfiles; 1012 fdp->fd_nfiles = nf; 1013 1014 if (oldfiles != fdp->fd_builtin_files) { 1015 spin_unlock_wr(&fdp->fd_spin); 1016 kfree(oldfiles, M_FILEDESC); 1017 spin_lock_wr(&fdp->fd_spin); 1018 } 1019 fdexpand++; 1020 } 1021 1022 /* 1023 * Number of nodes in right subtree, including the root. 1024 */ 1025 static __inline int 1026 right_subtree_size(int n) 1027 { 1028 return (n ^ (n | (n + 1))); 1029 } 1030 1031 /* 1032 * Bigger ancestor. 1033 */ 1034 static __inline int 1035 right_ancestor(int n) 1036 { 1037 return (n | (n + 1)); 1038 } 1039 1040 /* 1041 * Smaller ancestor. 1042 */ 1043 static __inline int 1044 left_ancestor(int n) 1045 { 1046 return ((n & (n + 1)) - 1); 1047 } 1048 1049 /* 1050 * Traverse the in-place binary tree buttom-up adjusting the allocation 1051 * count so scans can determine where free descriptors are located. 1052 * 1053 * MPSAFE - caller must be holding an exclusive spinlock on fdp 1054 */ 1055 static 1056 void 1057 fdreserve_locked(struct filedesc *fdp, int fd, int incr) 1058 { 1059 while (fd >= 0) { 1060 fdp->fd_files[fd].allocated += incr; 1061 KKASSERT(fdp->fd_files[fd].allocated >= 0); 1062 fd = left_ancestor(fd); 1063 } 1064 } 1065 1066 /* 1067 * Reserve a file descriptor for the process. If no error occurs, the 1068 * caller MUST at some point call fsetfd() or assign a file pointer 1069 * or dispose of the reservation. 1070 * 1071 * MPSAFE 1072 */ 1073 int 1074 fdalloc(struct proc *p, int want, int *result) 1075 { 1076 struct filedesc *fdp = p->p_fd; 1077 int fd, rsize, rsum, node, lim; 1078 1079 spin_lock_rd(&p->p_limit->p_spin); 1080 lim = min((int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur, maxfilesperproc); 1081 spin_unlock_rd(&p->p_limit->p_spin); 1082 if (want >= lim) 1083 return (EMFILE); 1084 spin_lock_wr(&fdp->fd_spin); 1085 if (want >= fdp->fd_nfiles) 1086 fdgrow_locked(fdp, want); 1087 1088 /* 1089 * Search for a free descriptor starting at the higher 1090 * of want or fd_freefile. If that fails, consider 1091 * expanding the ofile array. 1092 * 1093 * NOTE! the 'allocated' field is a cumulative recursive allocation 1094 * count. If we happen to see a value of 0 then we can shortcut 1095 * our search. Otherwise we run through through the tree going 1096 * down branches we know have free descriptor(s) until we hit a 1097 * leaf node. The leaf node will be free but will not necessarily 1098 * have an allocated field of 0. 1099 */ 1100 retry: 1101 /* move up the tree looking for a subtree with a free node */ 1102 for (fd = max(want, fdp->fd_freefile); fd < min(fdp->fd_nfiles, lim); 1103 fd = right_ancestor(fd)) { 1104 if (fdp->fd_files[fd].allocated == 0) 1105 goto found; 1106 1107 rsize = right_subtree_size(fd); 1108 if (fdp->fd_files[fd].allocated == rsize) 1109 continue; /* right subtree full */ 1110 1111 /* 1112 * Free fd is in the right subtree of the tree rooted at fd. 1113 * Call that subtree R. Look for the smallest (leftmost) 1114 * subtree of R with an unallocated fd: continue moving 1115 * down the left branch until encountering a full left 1116 * subtree, then move to the right. 1117 */ 1118 for (rsum = 0, rsize /= 2; rsize > 0; rsize /= 2) { 1119 node = fd + rsize; 1120 rsum += fdp->fd_files[node].allocated; 1121 if (fdp->fd_files[fd].allocated == rsum + rsize) { 1122 fd = node; /* move to the right */ 1123 if (fdp->fd_files[node].allocated == 0) 1124 goto found; 1125 rsum = 0; 1126 } 1127 } 1128 goto found; 1129 } 1130 1131 /* 1132 * No space in current array. Expand? 1133 */ 1134 if (fdp->fd_nfiles >= lim) { 1135 spin_unlock_wr(&fdp->fd_spin); 1136 return (EMFILE); 1137 } 1138 fdgrow_locked(fdp, want); 1139 goto retry; 1140 1141 found: 1142 KKASSERT(fd < fdp->fd_nfiles); 1143 if (fd > fdp->fd_lastfile) 1144 fdp->fd_lastfile = fd; 1145 if (want <= fdp->fd_freefile) 1146 fdp->fd_freefile = fd; 1147 *result = fd; 1148 KKASSERT(fdp->fd_files[fd].fp == NULL); 1149 KKASSERT(fdp->fd_files[fd].reserved == 0); 1150 fdp->fd_files[fd].fileflags = 0; 1151 fdp->fd_files[fd].reserved = 1; 1152 fdreserve_locked(fdp, fd, 1); 1153 spin_unlock_wr(&fdp->fd_spin); 1154 return (0); 1155 } 1156 1157 /* 1158 * Check to see whether n user file descriptors 1159 * are available to the process p. 1160 * 1161 * MPSAFE 1162 */ 1163 int 1164 fdavail(struct proc *p, int n) 1165 { 1166 struct filedesc *fdp = p->p_fd; 1167 struct fdnode *fdnode; 1168 int i, lim, last; 1169 1170 spin_lock_rd(&p->p_limit->p_spin); 1171 lim = min((int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur, maxfilesperproc); 1172 spin_unlock_rd(&p->p_limit->p_spin); 1173 1174 spin_lock_rd(&fdp->fd_spin); 1175 if ((i = lim - fdp->fd_nfiles) > 0 && (n -= i) <= 0) { 1176 spin_unlock_rd(&fdp->fd_spin); 1177 return (1); 1178 } 1179 last = min(fdp->fd_nfiles, lim); 1180 fdnode = &fdp->fd_files[fdp->fd_freefile]; 1181 for (i = last - fdp->fd_freefile; --i >= 0; ++fdnode) { 1182 if (fdnode->fp == NULL && --n <= 0) { 1183 spin_unlock_rd(&fdp->fd_spin); 1184 return (1); 1185 } 1186 } 1187 spin_unlock_rd(&fdp->fd_spin); 1188 return (0); 1189 } 1190 1191 /* 1192 * Revoke open descriptors referencing (f_data, f_type) 1193 * 1194 * Any revoke executed within a prison is only able to 1195 * revoke descriptors for processes within that prison. 1196 * 1197 * Returns 0 on success or an error code. 1198 */ 1199 struct fdrevoke_info { 1200 void *data; 1201 short type; 1202 short unused; 1203 int count; 1204 int intransit; 1205 struct ucred *cred; 1206 struct file *nfp; 1207 }; 1208 1209 static int fdrevoke_check_callback(struct file *fp, void *vinfo); 1210 static int fdrevoke_proc_callback(struct proc *p, void *vinfo); 1211 1212 int 1213 fdrevoke(void *f_data, short f_type, struct ucred *cred) 1214 { 1215 struct fdrevoke_info info; 1216 int error; 1217 1218 bzero(&info, sizeof(info)); 1219 info.data = f_data; 1220 info.type = f_type; 1221 info.cred = cred; 1222 error = falloc(NULL, &info.nfp, NULL); 1223 if (error) 1224 return (error); 1225 1226 /* 1227 * Scan the file pointer table once. dups do not dup file pointers, 1228 * only descriptors, so there is no leak. Set FREVOKED on the fps 1229 * being revoked. 1230 */ 1231 allfiles_scan_exclusive(fdrevoke_check_callback, &info); 1232 1233 /* 1234 * If any fps were marked track down the related descriptors 1235 * and close them. Any dup()s at this point will notice 1236 * the FREVOKED already set in the fp and do the right thing. 1237 * 1238 * Any fps with non-zero msgcounts (aka sent over a unix-domain 1239 * socket) bumped the intransit counter and will require a 1240 * scan. Races against fps leaving the socket are closed by 1241 * the socket code checking for FREVOKED. 1242 */ 1243 if (info.count) 1244 allproc_scan(fdrevoke_proc_callback, &info); 1245 if (info.intransit) 1246 unp_revoke_gc(info.nfp); 1247 fdrop(info.nfp); 1248 return(0); 1249 } 1250 1251 /* 1252 * Locate matching file pointers directly. 1253 */ 1254 static int 1255 fdrevoke_check_callback(struct file *fp, void *vinfo) 1256 { 1257 struct fdrevoke_info *info = vinfo; 1258 1259 /* 1260 * File pointers already flagged for revokation are skipped. 1261 */ 1262 if (fp->f_flag & FREVOKED) 1263 return(0); 1264 1265 /* 1266 * If revoking from a prison file pointers created outside of 1267 * that prison, or file pointers without creds, cannot be revoked. 1268 */ 1269 if (info->cred->cr_prison && 1270 (fp->f_cred == NULL || 1271 info->cred->cr_prison != fp->f_cred->cr_prison)) { 1272 return(0); 1273 } 1274 1275 /* 1276 * If the file pointer matches then mark it for revocation. The 1277 * flag is currently only used by unp_revoke_gc(). 1278 * 1279 * info->count is a heuristic and can race in a SMP environment. 1280 */ 1281 if (info->data == fp->f_data && info->type == fp->f_type) { 1282 atomic_set_int(&fp->f_flag, FREVOKED); 1283 info->count += fp->f_count; 1284 if (fp->f_msgcount) 1285 ++info->intransit; 1286 } 1287 return(0); 1288 } 1289 1290 /* 1291 * Locate matching file pointers via process descriptor tables. 1292 */ 1293 static int 1294 fdrevoke_proc_callback(struct proc *p, void *vinfo) 1295 { 1296 struct fdrevoke_info *info = vinfo; 1297 struct filedesc *fdp; 1298 struct file *fp; 1299 int n; 1300 1301 if (p->p_stat == SIDL || p->p_stat == SZOMB) 1302 return(0); 1303 if (info->cred->cr_prison && 1304 info->cred->cr_prison != p->p_ucred->cr_prison) { 1305 return(0); 1306 } 1307 1308 /* 1309 * If the controlling terminal of the process matches the 1310 * vnode being revoked we clear the controlling terminal. 1311 * 1312 * The normal spec_close() may not catch this because it 1313 * uses curproc instead of p. 1314 */ 1315 if (p->p_session && info->type == DTYPE_VNODE && 1316 info->data == p->p_session->s_ttyvp) { 1317 p->p_session->s_ttyvp = NULL; 1318 vrele(info->data); 1319 } 1320 1321 /* 1322 * Softref the fdp to prevent it from being destroyed 1323 */ 1324 spin_lock_wr(&p->p_spin); 1325 if ((fdp = p->p_fd) == NULL) { 1326 spin_unlock_wr(&p->p_spin); 1327 return(0); 1328 } 1329 atomic_add_int(&fdp->fd_softrefs, 1); 1330 spin_unlock_wr(&p->p_spin); 1331 1332 /* 1333 * Locate and close any matching file descriptors. 1334 */ 1335 spin_lock_wr(&fdp->fd_spin); 1336 for (n = 0; n < fdp->fd_nfiles; ++n) { 1337 if ((fp = fdp->fd_files[n].fp) == NULL) 1338 continue; 1339 if (fp->f_flag & FREVOKED) { 1340 fhold(info->nfp); 1341 fdp->fd_files[n].fp = info->nfp; 1342 spin_unlock_wr(&fdp->fd_spin); 1343 closef(fp, p); 1344 spin_lock_wr(&fdp->fd_spin); 1345 --info->count; 1346 } 1347 } 1348 spin_unlock_wr(&fdp->fd_spin); 1349 atomic_subtract_int(&fdp->fd_softrefs, 1); 1350 return(0); 1351 } 1352 1353 /* 1354 * falloc: 1355 * Create a new open file structure and reserve a file decriptor 1356 * for the process that refers to it. 1357 * 1358 * Root creds are checked using p, or assumed if p is NULL. If 1359 * resultfd is non-NULL then p must also be non-NULL. No file 1360 * descriptor is reserved if resultfd is NULL. 1361 * 1362 * A file pointer with a refcount of 1 is returned. Note that the 1363 * file pointer is NOT associated with the descriptor. If falloc 1364 * returns success, fsetfd() MUST be called to either associate the 1365 * file pointer or clear the reservation. 1366 * 1367 * MPSAFE 1368 */ 1369 int 1370 falloc(struct proc *p, struct file **resultfp, int *resultfd) 1371 { 1372 static struct timeval lastfail; 1373 static int curfail; 1374 struct file *fp; 1375 int error; 1376 1377 fp = NULL; 1378 1379 /* 1380 * Handle filetable full issues and root overfill. 1381 */ 1382 if (nfiles >= maxfiles - maxfilesrootres && 1383 ((p && p->p_ucred->cr_ruid != 0) || nfiles >= maxfiles)) { 1384 if (ppsratecheck(&lastfail, &curfail, 1)) { 1385 kprintf("kern.maxfiles limit exceeded by uid %d, please see tuning(7).\n", 1386 (p ? p->p_ucred->cr_ruid : -1)); 1387 } 1388 error = ENFILE; 1389 goto done; 1390 } 1391 1392 /* 1393 * Allocate a new file descriptor. 1394 */ 1395 fp = kmalloc(sizeof(struct file), M_FILE, M_WAITOK | M_ZERO); 1396 spin_init(&fp->f_spin); 1397 fp->f_count = 1; 1398 fp->f_ops = &badfileops; 1399 fp->f_seqcount = 1; 1400 if (p) 1401 fp->f_cred = crhold(p->p_ucred); 1402 else 1403 fp->f_cred = crhold(proc0.p_ucred); 1404 spin_lock_wr(&filehead_spin); 1405 nfiles++; 1406 LIST_INSERT_HEAD(&filehead, fp, f_list); 1407 spin_unlock_wr(&filehead_spin); 1408 if (resultfd) { 1409 if ((error = fdalloc(p, 0, resultfd)) != 0) { 1410 fdrop(fp); 1411 fp = NULL; 1412 } 1413 } else { 1414 error = 0; 1415 } 1416 done: 1417 *resultfp = fp; 1418 return (error); 1419 } 1420 1421 /* 1422 * MPSAFE 1423 */ 1424 static 1425 int 1426 checkfpclosed(struct filedesc *fdp, int fd, struct file *fp) 1427 { 1428 int error; 1429 1430 spin_lock_rd(&fdp->fd_spin); 1431 if ((unsigned) fd >= fdp->fd_nfiles || fp != fdp->fd_files[fd].fp) 1432 error = EBADF; 1433 else 1434 error = 0; 1435 spin_unlock_rd(&fdp->fd_spin); 1436 return (error); 1437 } 1438 1439 /* 1440 * Associate a file pointer with a previously reserved file descriptor. 1441 * This function always succeeds. 1442 * 1443 * If fp is NULL, the file descriptor is returned to the pool. 1444 */ 1445 1446 /* 1447 * MPSAFE (exclusive spinlock must be held on call) 1448 */ 1449 static void 1450 fsetfd_locked(struct filedesc *fdp, struct file *fp, int fd) 1451 { 1452 KKASSERT((unsigned)fd < fdp->fd_nfiles); 1453 KKASSERT(fdp->fd_files[fd].reserved != 0); 1454 if (fp) { 1455 fhold(fp); 1456 fdp->fd_files[fd].fp = fp; 1457 fdp->fd_files[fd].reserved = 0; 1458 if (fp->f_type == DTYPE_KQUEUE) { 1459 if (fdp->fd_knlistsize < 0) 1460 fdp->fd_knlistsize = 0; 1461 } 1462 } else { 1463 fdp->fd_files[fd].reserved = 0; 1464 fdreserve_locked(fdp, fd, -1); 1465 fdfixup_locked(fdp, fd); 1466 } 1467 } 1468 1469 /* 1470 * MPSAFE 1471 */ 1472 void 1473 fsetfd(struct proc *p, struct file *fp, int fd) 1474 { 1475 struct filedesc *fdp = p->p_fd; 1476 1477 spin_lock_wr(&fdp->fd_spin); 1478 fsetfd_locked(fdp, fp, fd); 1479 spin_unlock_wr(&fdp->fd_spin); 1480 } 1481 1482 /* 1483 * MPSAFE (exclusive spinlock must be held on call) 1484 */ 1485 static 1486 struct file * 1487 funsetfd_locked(struct filedesc *fdp, int fd) 1488 { 1489 struct file *fp; 1490 1491 if ((unsigned)fd >= fdp->fd_nfiles) 1492 return (NULL); 1493 if ((fp = fdp->fd_files[fd].fp) == NULL) 1494 return (NULL); 1495 fdp->fd_files[fd].fp = NULL; 1496 fdp->fd_files[fd].fileflags = 0; 1497 1498 fdreserve_locked(fdp, fd, -1); 1499 fdfixup_locked(fdp, fd); 1500 return(fp); 1501 } 1502 1503 /* 1504 * MPSAFE 1505 */ 1506 int 1507 fgetfdflags(struct filedesc *fdp, int fd, int *flagsp) 1508 { 1509 int error; 1510 1511 spin_lock_rd(&fdp->fd_spin); 1512 if (((u_int)fd) >= fdp->fd_nfiles) { 1513 error = EBADF; 1514 } else if (fdp->fd_files[fd].fp == NULL) { 1515 error = EBADF; 1516 } else { 1517 *flagsp = fdp->fd_files[fd].fileflags; 1518 error = 0; 1519 } 1520 spin_unlock_rd(&fdp->fd_spin); 1521 return (error); 1522 } 1523 1524 /* 1525 * MPSAFE 1526 */ 1527 int 1528 fsetfdflags(struct filedesc *fdp, int fd, int add_flags) 1529 { 1530 int error; 1531 1532 spin_lock_wr(&fdp->fd_spin); 1533 if (((u_int)fd) >= fdp->fd_nfiles) { 1534 error = EBADF; 1535 } else if (fdp->fd_files[fd].fp == NULL) { 1536 error = EBADF; 1537 } else { 1538 fdp->fd_files[fd].fileflags |= add_flags; 1539 error = 0; 1540 } 1541 spin_unlock_wr(&fdp->fd_spin); 1542 return (error); 1543 } 1544 1545 /* 1546 * MPSAFE 1547 */ 1548 int 1549 fclrfdflags(struct filedesc *fdp, int fd, int rem_flags) 1550 { 1551 int error; 1552 1553 spin_lock_wr(&fdp->fd_spin); 1554 if (((u_int)fd) >= fdp->fd_nfiles) { 1555 error = EBADF; 1556 } else if (fdp->fd_files[fd].fp == NULL) { 1557 error = EBADF; 1558 } else { 1559 fdp->fd_files[fd].fileflags &= ~rem_flags; 1560 error = 0; 1561 } 1562 spin_unlock_wr(&fdp->fd_spin); 1563 return (error); 1564 } 1565 1566 void 1567 fsetcred(struct file *fp, struct ucred *cr) 1568 { 1569 crhold(cr); 1570 crfree(fp->f_cred); 1571 fp->f_cred = cr; 1572 } 1573 1574 /* 1575 * Free a file descriptor. 1576 */ 1577 static 1578 void 1579 ffree(struct file *fp) 1580 { 1581 KASSERT((fp->f_count == 0), ("ffree: fp_fcount not 0!")); 1582 spin_lock_wr(&filehead_spin); 1583 LIST_REMOVE(fp, f_list); 1584 nfiles--; 1585 spin_unlock_wr(&filehead_spin); 1586 crfree(fp->f_cred); 1587 if (fp->f_nchandle.ncp) 1588 cache_drop(&fp->f_nchandle); 1589 kfree(fp, M_FILE); 1590 } 1591 1592 /* 1593 * called from init_main, initialize filedesc0 for proc0. 1594 */ 1595 void 1596 fdinit_bootstrap(struct proc *p0, struct filedesc *fdp0, int cmask) 1597 { 1598 p0->p_fd = fdp0; 1599 p0->p_fdtol = NULL; 1600 fdp0->fd_refcnt = 1; 1601 fdp0->fd_cmask = cmask; 1602 fdp0->fd_files = fdp0->fd_builtin_files; 1603 fdp0->fd_nfiles = NDFILE; 1604 fdp0->fd_lastfile = -1; 1605 spin_init(&fdp0->fd_spin); 1606 } 1607 1608 /* 1609 * Build a new filedesc structure. 1610 * 1611 * NOT MPSAFE (vref) 1612 */ 1613 struct filedesc * 1614 fdinit(struct proc *p) 1615 { 1616 struct filedesc *newfdp; 1617 struct filedesc *fdp = p->p_fd; 1618 1619 newfdp = kmalloc(sizeof(struct filedesc), M_FILEDESC, M_WAITOK|M_ZERO); 1620 spin_lock_rd(&fdp->fd_spin); 1621 if (fdp->fd_cdir) { 1622 newfdp->fd_cdir = fdp->fd_cdir; 1623 vref(newfdp->fd_cdir); 1624 cache_copy(&fdp->fd_ncdir, &newfdp->fd_ncdir); 1625 } 1626 1627 /* 1628 * rdir may not be set in e.g. proc0 or anything vm_fork'd off of 1629 * proc0, but should unconditionally exist in other processes. 1630 */ 1631 if (fdp->fd_rdir) { 1632 newfdp->fd_rdir = fdp->fd_rdir; 1633 vref(newfdp->fd_rdir); 1634 cache_copy(&fdp->fd_nrdir, &newfdp->fd_nrdir); 1635 } 1636 if (fdp->fd_jdir) { 1637 newfdp->fd_jdir = fdp->fd_jdir; 1638 vref(newfdp->fd_jdir); 1639 cache_copy(&fdp->fd_njdir, &newfdp->fd_njdir); 1640 } 1641 spin_unlock_rd(&fdp->fd_spin); 1642 1643 /* Create the file descriptor table. */ 1644 newfdp->fd_refcnt = 1; 1645 newfdp->fd_cmask = cmask; 1646 newfdp->fd_files = newfdp->fd_builtin_files; 1647 newfdp->fd_nfiles = NDFILE; 1648 newfdp->fd_knlistsize = -1; 1649 newfdp->fd_lastfile = -1; 1650 spin_init(&newfdp->fd_spin); 1651 1652 return (newfdp); 1653 } 1654 1655 /* 1656 * Share a filedesc structure. 1657 * 1658 * MPSAFE 1659 */ 1660 struct filedesc * 1661 fdshare(struct proc *p) 1662 { 1663 struct filedesc *fdp; 1664 1665 fdp = p->p_fd; 1666 spin_lock_wr(&fdp->fd_spin); 1667 fdp->fd_refcnt++; 1668 spin_unlock_wr(&fdp->fd_spin); 1669 return (fdp); 1670 } 1671 1672 /* 1673 * Copy a filedesc structure. 1674 * 1675 * MPSAFE 1676 */ 1677 struct filedesc * 1678 fdcopy(struct proc *p) 1679 { 1680 struct filedesc *fdp = p->p_fd; 1681 struct filedesc *newfdp; 1682 struct fdnode *fdnode; 1683 int i; 1684 int ni; 1685 1686 /* 1687 * Certain daemons might not have file descriptors. 1688 */ 1689 if (fdp == NULL) 1690 return (NULL); 1691 1692 /* 1693 * Allocate the new filedesc and fd_files[] array. This can race 1694 * with operations by other threads on the fdp so we have to be 1695 * careful. 1696 */ 1697 newfdp = kmalloc(sizeof(struct filedesc), M_FILEDESC, M_WAITOK | M_ZERO); 1698 again: 1699 spin_lock_rd(&fdp->fd_spin); 1700 if (fdp->fd_lastfile < NDFILE) { 1701 newfdp->fd_files = newfdp->fd_builtin_files; 1702 i = NDFILE; 1703 } else { 1704 /* 1705 * We have to allocate (N^2-1) entries for our in-place 1706 * binary tree. Allow the table to shrink. 1707 */ 1708 i = fdp->fd_nfiles; 1709 ni = (i - 1) / 2; 1710 while (ni > fdp->fd_lastfile && ni > NDFILE) { 1711 i = ni; 1712 ni = (i - 1) / 2; 1713 } 1714 spin_unlock_rd(&fdp->fd_spin); 1715 newfdp->fd_files = kmalloc(i * sizeof(struct fdnode), 1716 M_FILEDESC, M_WAITOK | M_ZERO); 1717 1718 /* 1719 * Check for race, retry 1720 */ 1721 spin_lock_rd(&fdp->fd_spin); 1722 if (i <= fdp->fd_lastfile) { 1723 spin_unlock_rd(&fdp->fd_spin); 1724 kfree(newfdp->fd_files, M_FILEDESC); 1725 goto again; 1726 } 1727 } 1728 1729 /* 1730 * Dup the remaining fields. vref() and cache_hold() can be 1731 * safely called while holding the read spinlock on fdp. 1732 * 1733 * The read spinlock on fdp is still being held. 1734 * 1735 * NOTE: vref and cache_hold calls for the case where the vnode 1736 * or cache entry already has at least one ref may be called 1737 * while holding spin locks. 1738 */ 1739 if ((newfdp->fd_cdir = fdp->fd_cdir) != NULL) { 1740 vref(newfdp->fd_cdir); 1741 cache_copy(&fdp->fd_ncdir, &newfdp->fd_ncdir); 1742 } 1743 /* 1744 * We must check for fd_rdir here, at least for now because 1745 * the init process is created before we have access to the 1746 * rootvode to take a reference to it. 1747 */ 1748 if ((newfdp->fd_rdir = fdp->fd_rdir) != NULL) { 1749 vref(newfdp->fd_rdir); 1750 cache_copy(&fdp->fd_nrdir, &newfdp->fd_nrdir); 1751 } 1752 if ((newfdp->fd_jdir = fdp->fd_jdir) != NULL) { 1753 vref(newfdp->fd_jdir); 1754 cache_copy(&fdp->fd_njdir, &newfdp->fd_njdir); 1755 } 1756 newfdp->fd_refcnt = 1; 1757 newfdp->fd_nfiles = i; 1758 newfdp->fd_lastfile = fdp->fd_lastfile; 1759 newfdp->fd_freefile = fdp->fd_freefile; 1760 newfdp->fd_cmask = fdp->fd_cmask; 1761 newfdp->fd_knlist = NULL; 1762 newfdp->fd_knlistsize = -1; 1763 newfdp->fd_knhash = NULL; 1764 newfdp->fd_knhashmask = 0; 1765 spin_init(&newfdp->fd_spin); 1766 1767 /* 1768 * Copy the descriptor table through (i). This also copies the 1769 * allocation state. Then go through and ref the file pointers 1770 * and clean up any KQ descriptors. 1771 * 1772 * kq descriptors cannot be copied. Since we haven't ref'd the 1773 * copied files yet we can ignore the return value from funsetfd(). 1774 * 1775 * The read spinlock on fdp is still being held. 1776 */ 1777 bcopy(fdp->fd_files, newfdp->fd_files, i * sizeof(struct fdnode)); 1778 for (i = 0 ; i < newfdp->fd_nfiles; ++i) { 1779 fdnode = &newfdp->fd_files[i]; 1780 if (fdnode->reserved) { 1781 fdreserve_locked(newfdp, i, -1); 1782 fdnode->reserved = 0; 1783 fdfixup_locked(newfdp, i); 1784 } else if (fdnode->fp) { 1785 if (fdnode->fp->f_type == DTYPE_KQUEUE) { 1786 (void)funsetfd_locked(newfdp, i); 1787 } else { 1788 fhold(fdnode->fp); 1789 } 1790 } 1791 } 1792 spin_unlock_rd(&fdp->fd_spin); 1793 return (newfdp); 1794 } 1795 1796 /* 1797 * Release a filedesc structure. 1798 * 1799 * NOT MPSAFE (MPSAFE for refs > 1, but the final cleanup code is not MPSAFE) 1800 */ 1801 void 1802 fdfree(struct proc *p, struct filedesc *repl) 1803 { 1804 struct filedesc *fdp; 1805 struct fdnode *fdnode; 1806 int i; 1807 struct filedesc_to_leader *fdtol; 1808 struct file *fp; 1809 struct vnode *vp; 1810 struct flock lf; 1811 1812 /* 1813 * Certain daemons might not have file descriptors. 1814 */ 1815 fdp = p->p_fd; 1816 if (fdp == NULL) { 1817 p->p_fd = repl; 1818 return; 1819 } 1820 1821 /* 1822 * Severe messing around to follow. 1823 */ 1824 spin_lock_wr(&fdp->fd_spin); 1825 1826 /* Check for special need to clear POSIX style locks */ 1827 fdtol = p->p_fdtol; 1828 if (fdtol != NULL) { 1829 KASSERT(fdtol->fdl_refcount > 0, 1830 ("filedesc_to_refcount botch: fdl_refcount=%d", 1831 fdtol->fdl_refcount)); 1832 if (fdtol->fdl_refcount == 1 && 1833 (p->p_leader->p_flag & P_ADVLOCK) != 0) { 1834 for (i = 0; i <= fdp->fd_lastfile; ++i) { 1835 fdnode = &fdp->fd_files[i]; 1836 if (fdnode->fp == NULL || 1837 fdnode->fp->f_type != DTYPE_VNODE) { 1838 continue; 1839 } 1840 fp = fdnode->fp; 1841 fhold(fp); 1842 spin_unlock_wr(&fdp->fd_spin); 1843 1844 lf.l_whence = SEEK_SET; 1845 lf.l_start = 0; 1846 lf.l_len = 0; 1847 lf.l_type = F_UNLCK; 1848 vp = (struct vnode *)fp->f_data; 1849 (void) VOP_ADVLOCK(vp, 1850 (caddr_t)p->p_leader, 1851 F_UNLCK, 1852 &lf, 1853 F_POSIX); 1854 fdrop(fp); 1855 spin_lock_wr(&fdp->fd_spin); 1856 } 1857 } 1858 retry: 1859 if (fdtol->fdl_refcount == 1) { 1860 if (fdp->fd_holdleaderscount > 0 && 1861 (p->p_leader->p_flag & P_ADVLOCK) != 0) { 1862 /* 1863 * close() or do_dup() has cleared a reference 1864 * in a shared file descriptor table. 1865 */ 1866 fdp->fd_holdleaderswakeup = 1; 1867 msleep(&fdp->fd_holdleaderscount, 1868 &fdp->fd_spin, 0, "fdlhold", 0); 1869 goto retry; 1870 } 1871 if (fdtol->fdl_holdcount > 0) { 1872 /* 1873 * Ensure that fdtol->fdl_leader 1874 * remains valid in closef(). 1875 */ 1876 fdtol->fdl_wakeup = 1; 1877 msleep(fdtol, &fdp->fd_spin, 0, "fdlhold", 0); 1878 goto retry; 1879 } 1880 } 1881 fdtol->fdl_refcount--; 1882 if (fdtol->fdl_refcount == 0 && 1883 fdtol->fdl_holdcount == 0) { 1884 fdtol->fdl_next->fdl_prev = fdtol->fdl_prev; 1885 fdtol->fdl_prev->fdl_next = fdtol->fdl_next; 1886 } else { 1887 fdtol = NULL; 1888 } 1889 p->p_fdtol = NULL; 1890 if (fdtol != NULL) { 1891 spin_unlock_wr(&fdp->fd_spin); 1892 kfree(fdtol, M_FILEDESC_TO_LEADER); 1893 spin_lock_wr(&fdp->fd_spin); 1894 } 1895 } 1896 if (--fdp->fd_refcnt > 0) { 1897 spin_unlock_wr(&fdp->fd_spin); 1898 spin_lock_wr(&p->p_spin); 1899 p->p_fd = repl; 1900 spin_unlock_wr(&p->p_spin); 1901 return; 1902 } 1903 1904 /* 1905 * Even though we are the last reference to the structure allproc 1906 * scans may still reference the structure. Maintain proper 1907 * locks until we can replace p->p_fd. 1908 * 1909 * Also note that kqueue's closef still needs to reference the 1910 * fdp via p->p_fd, so we have to close the descriptors before 1911 * we replace p->p_fd. 1912 */ 1913 for (i = 0; i <= fdp->fd_lastfile; ++i) { 1914 if (fdp->fd_files[i].fp) { 1915 fp = funsetfd_locked(fdp, i); 1916 if (fp) { 1917 spin_unlock_wr(&fdp->fd_spin); 1918 closef(fp, p); 1919 spin_lock_wr(&fdp->fd_spin); 1920 } 1921 } 1922 } 1923 spin_unlock_wr(&fdp->fd_spin); 1924 1925 /* 1926 * Interlock against an allproc scan operations (typically frevoke). 1927 */ 1928 spin_lock_wr(&p->p_spin); 1929 p->p_fd = repl; 1930 spin_unlock_wr(&p->p_spin); 1931 1932 /* 1933 * Wait for any softrefs to go away. This race rarely occurs so 1934 * we can use a non-critical-path style poll/sleep loop. The 1935 * race only occurs against allproc scans. 1936 * 1937 * No new softrefs can occur with the fdp disconnected from the 1938 * process. 1939 */ 1940 if (fdp->fd_softrefs) { 1941 kprintf("pid %d: Warning, fdp race avoided\n", p->p_pid); 1942 while (fdp->fd_softrefs) 1943 tsleep(&fdp->fd_softrefs, 0, "fdsoft", 1); 1944 } 1945 1946 if (fdp->fd_files != fdp->fd_builtin_files) 1947 kfree(fdp->fd_files, M_FILEDESC); 1948 if (fdp->fd_cdir) { 1949 cache_drop(&fdp->fd_ncdir); 1950 vrele(fdp->fd_cdir); 1951 } 1952 if (fdp->fd_rdir) { 1953 cache_drop(&fdp->fd_nrdir); 1954 vrele(fdp->fd_rdir); 1955 } 1956 if (fdp->fd_jdir) { 1957 cache_drop(&fdp->fd_njdir); 1958 vrele(fdp->fd_jdir); 1959 } 1960 if (fdp->fd_knlist) 1961 kfree(fdp->fd_knlist, M_KQUEUE); 1962 if (fdp->fd_knhash) 1963 kfree(fdp->fd_knhash, M_KQUEUE); 1964 kfree(fdp, M_FILEDESC); 1965 } 1966 1967 /* 1968 * Retrieve and reference the file pointer associated with a descriptor. 1969 * 1970 * MPSAFE 1971 */ 1972 struct file * 1973 holdfp(struct filedesc *fdp, int fd, int flag) 1974 { 1975 struct file* fp; 1976 1977 spin_lock_rd(&fdp->fd_spin); 1978 if (((u_int)fd) >= fdp->fd_nfiles) { 1979 fp = NULL; 1980 goto done; 1981 } 1982 if ((fp = fdp->fd_files[fd].fp) == NULL) 1983 goto done; 1984 if ((fp->f_flag & flag) == 0 && flag != -1) { 1985 fp = NULL; 1986 goto done; 1987 } 1988 fhold(fp); 1989 done: 1990 spin_unlock_rd(&fdp->fd_spin); 1991 return (fp); 1992 } 1993 1994 /* 1995 * holdsock() - load the struct file pointer associated 1996 * with a socket into *fpp. If an error occurs, non-zero 1997 * will be returned and *fpp will be set to NULL. 1998 * 1999 * MPSAFE 2000 */ 2001 int 2002 holdsock(struct filedesc *fdp, int fd, struct file **fpp) 2003 { 2004 struct file *fp; 2005 int error; 2006 2007 spin_lock_rd(&fdp->fd_spin); 2008 if ((unsigned)fd >= fdp->fd_nfiles) { 2009 error = EBADF; 2010 fp = NULL; 2011 goto done; 2012 } 2013 if ((fp = fdp->fd_files[fd].fp) == NULL) { 2014 error = EBADF; 2015 goto done; 2016 } 2017 if (fp->f_type != DTYPE_SOCKET) { 2018 error = ENOTSOCK; 2019 goto done; 2020 } 2021 fhold(fp); 2022 error = 0; 2023 done: 2024 spin_unlock_rd(&fdp->fd_spin); 2025 *fpp = fp; 2026 return (error); 2027 } 2028 2029 /* 2030 * Convert a user file descriptor to a held file pointer. 2031 * 2032 * MPSAFE 2033 */ 2034 int 2035 holdvnode(struct filedesc *fdp, int fd, struct file **fpp) 2036 { 2037 struct file *fp; 2038 int error; 2039 2040 spin_lock_rd(&fdp->fd_spin); 2041 if ((unsigned)fd >= fdp->fd_nfiles) { 2042 error = EBADF; 2043 fp = NULL; 2044 goto done; 2045 } 2046 if ((fp = fdp->fd_files[fd].fp) == NULL) { 2047 error = EBADF; 2048 goto done; 2049 } 2050 if (fp->f_type != DTYPE_VNODE && fp->f_type != DTYPE_FIFO) { 2051 fp = NULL; 2052 error = EINVAL; 2053 goto done; 2054 } 2055 fhold(fp); 2056 error = 0; 2057 done: 2058 spin_unlock_rd(&fdp->fd_spin); 2059 *fpp = fp; 2060 return (error); 2061 } 2062 2063 /* 2064 * For setugid programs, we don't want to people to use that setugidness 2065 * to generate error messages which write to a file which otherwise would 2066 * otherwise be off-limits to the process. 2067 * 2068 * This is a gross hack to plug the hole. A better solution would involve 2069 * a special vop or other form of generalized access control mechanism. We 2070 * go ahead and just reject all procfs file systems accesses as dangerous. 2071 * 2072 * Since setugidsafety calls this only for fd 0, 1 and 2, this check is 2073 * sufficient. We also don't for check setugidness since we know we are. 2074 */ 2075 static int 2076 is_unsafe(struct file *fp) 2077 { 2078 if (fp->f_type == DTYPE_VNODE && 2079 ((struct vnode *)(fp->f_data))->v_tag == VT_PROCFS) 2080 return (1); 2081 return (0); 2082 } 2083 2084 /* 2085 * Make this setguid thing safe, if at all possible. 2086 * 2087 * NOT MPSAFE - scans fdp without spinlocks, calls knote_fdclose() 2088 */ 2089 void 2090 setugidsafety(struct proc *p) 2091 { 2092 struct filedesc *fdp = p->p_fd; 2093 int i; 2094 2095 /* Certain daemons might not have file descriptors. */ 2096 if (fdp == NULL) 2097 return; 2098 2099 /* 2100 * note: fdp->fd_files may be reallocated out from under us while 2101 * we are blocked in a close. Be careful! 2102 */ 2103 for (i = 0; i <= fdp->fd_lastfile; i++) { 2104 if (i > 2) 2105 break; 2106 if (fdp->fd_files[i].fp && is_unsafe(fdp->fd_files[i].fp)) { 2107 struct file *fp; 2108 2109 if (i < fdp->fd_knlistsize) 2110 knote_fdclose(p, i); 2111 /* 2112 * NULL-out descriptor prior to close to avoid 2113 * a race while close blocks. 2114 */ 2115 if ((fp = funsetfd_locked(fdp, i)) != NULL) 2116 closef(fp, p); 2117 } 2118 } 2119 } 2120 2121 /* 2122 * Close any files on exec? 2123 * 2124 * NOT MPSAFE - scans fdp without spinlocks, calls knote_fdclose() 2125 */ 2126 void 2127 fdcloseexec(struct proc *p) 2128 { 2129 struct filedesc *fdp = p->p_fd; 2130 int i; 2131 2132 /* Certain daemons might not have file descriptors. */ 2133 if (fdp == NULL) 2134 return; 2135 2136 /* 2137 * We cannot cache fd_files since operations may block and rip 2138 * them out from under us. 2139 */ 2140 for (i = 0; i <= fdp->fd_lastfile; i++) { 2141 if (fdp->fd_files[i].fp != NULL && 2142 (fdp->fd_files[i].fileflags & UF_EXCLOSE)) { 2143 struct file *fp; 2144 2145 if (i < fdp->fd_knlistsize) 2146 knote_fdclose(p, i); 2147 /* 2148 * NULL-out descriptor prior to close to avoid 2149 * a race while close blocks. 2150 */ 2151 if ((fp = funsetfd_locked(fdp, i)) != NULL) 2152 closef(fp, p); 2153 } 2154 } 2155 } 2156 2157 /* 2158 * It is unsafe for set[ug]id processes to be started with file 2159 * descriptors 0..2 closed, as these descriptors are given implicit 2160 * significance in the Standard C library. fdcheckstd() will create a 2161 * descriptor referencing /dev/null for each of stdin, stdout, and 2162 * stderr that is not already open. 2163 * 2164 * NOT MPSAFE - calls falloc, vn_open, etc 2165 */ 2166 int 2167 fdcheckstd(struct proc *p) 2168 { 2169 struct nlookupdata nd; 2170 struct filedesc *fdp; 2171 struct file *fp; 2172 int retval; 2173 int i, error, flags, devnull; 2174 2175 fdp = p->p_fd; 2176 if (fdp == NULL) 2177 return (0); 2178 devnull = -1; 2179 error = 0; 2180 for (i = 0; i < 3; i++) { 2181 if (fdp->fd_files[i].fp != NULL) 2182 continue; 2183 if (devnull < 0) { 2184 if ((error = falloc(p, &fp, &devnull)) != 0) 2185 break; 2186 2187 error = nlookup_init(&nd, "/dev/null", UIO_SYSSPACE, 2188 NLC_FOLLOW|NLC_LOCKVP); 2189 flags = FREAD | FWRITE; 2190 if (error == 0) 2191 error = vn_open(&nd, fp, flags, 0); 2192 if (error == 0) 2193 fsetfd(p, fp, devnull); 2194 else 2195 fsetfd(p, NULL, devnull); 2196 fdrop(fp); 2197 nlookup_done(&nd); 2198 if (error) 2199 break; 2200 KKASSERT(i == devnull); 2201 } else { 2202 error = kern_dup(DUP_FIXED, devnull, i, &retval); 2203 if (error != 0) 2204 break; 2205 } 2206 } 2207 return (error); 2208 } 2209 2210 /* 2211 * Internal form of close. 2212 * Decrement reference count on file structure. 2213 * Note: td and/or p may be NULL when closing a file 2214 * that was being passed in a message. 2215 * 2216 * MPALMOSTSAFE - acquires mplock for VOP operations 2217 */ 2218 int 2219 closef(struct file *fp, struct proc *p) 2220 { 2221 struct vnode *vp; 2222 struct flock lf; 2223 struct filedesc_to_leader *fdtol; 2224 2225 if (fp == NULL) 2226 return (0); 2227 2228 /* 2229 * POSIX record locking dictates that any close releases ALL 2230 * locks owned by this process. This is handled by setting 2231 * a flag in the unlock to free ONLY locks obeying POSIX 2232 * semantics, and not to free BSD-style file locks. 2233 * If the descriptor was in a message, POSIX-style locks 2234 * aren't passed with the descriptor. 2235 */ 2236 if (p != NULL && fp->f_type == DTYPE_VNODE && 2237 (((struct vnode *)fp->f_data)->v_flag & VMAYHAVELOCKS) 2238 ) { 2239 get_mplock(); 2240 if ((p->p_leader->p_flag & P_ADVLOCK) != 0) { 2241 lf.l_whence = SEEK_SET; 2242 lf.l_start = 0; 2243 lf.l_len = 0; 2244 lf.l_type = F_UNLCK; 2245 vp = (struct vnode *)fp->f_data; 2246 (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK, 2247 &lf, F_POSIX); 2248 } 2249 fdtol = p->p_fdtol; 2250 if (fdtol != NULL) { 2251 /* 2252 * Handle special case where file descriptor table 2253 * is shared between multiple process leaders. 2254 */ 2255 for (fdtol = fdtol->fdl_next; 2256 fdtol != p->p_fdtol; 2257 fdtol = fdtol->fdl_next) { 2258 if ((fdtol->fdl_leader->p_flag & 2259 P_ADVLOCK) == 0) 2260 continue; 2261 fdtol->fdl_holdcount++; 2262 lf.l_whence = SEEK_SET; 2263 lf.l_start = 0; 2264 lf.l_len = 0; 2265 lf.l_type = F_UNLCK; 2266 vp = (struct vnode *)fp->f_data; 2267 (void) VOP_ADVLOCK(vp, 2268 (caddr_t)fdtol->fdl_leader, 2269 F_UNLCK, &lf, F_POSIX); 2270 fdtol->fdl_holdcount--; 2271 if (fdtol->fdl_holdcount == 0 && 2272 fdtol->fdl_wakeup != 0) { 2273 fdtol->fdl_wakeup = 0; 2274 wakeup(fdtol); 2275 } 2276 } 2277 } 2278 rel_mplock(); 2279 } 2280 return (fdrop(fp)); 2281 } 2282 2283 /* 2284 * MPSAFE 2285 * 2286 * fhold() can only be called if f_count is already at least 1 (i.e. the 2287 * caller of fhold() already has a reference to the file pointer in some 2288 * manner or other). 2289 * 2290 * f_count is not spin-locked. Instead, atomic ops are used for 2291 * incrementing, decrementing, and handling the 1->0 transition. 2292 */ 2293 void 2294 fhold(struct file *fp) 2295 { 2296 atomic_add_int(&fp->f_count, 1); 2297 } 2298 2299 /* 2300 * fdrop() - drop a reference to a descriptor 2301 * 2302 * MPALMOSTSAFE - acquires mplock for final close sequence 2303 */ 2304 int 2305 fdrop(struct file *fp) 2306 { 2307 struct flock lf; 2308 struct vnode *vp; 2309 int error; 2310 2311 /* 2312 * A combined fetch and subtract is needed to properly detect 2313 * 1->0 transitions, otherwise two cpus dropping from a ref 2314 * count of 2 might both try to run the 1->0 code. 2315 */ 2316 if (atomic_fetchadd_int(&fp->f_count, -1) > 1) 2317 return (0); 2318 2319 get_mplock(); 2320 2321 /* 2322 * The last reference has gone away, we own the fp structure free 2323 * and clear. 2324 */ 2325 if (fp->f_count < 0) 2326 panic("fdrop: count < 0"); 2327 if ((fp->f_flag & FHASLOCK) && fp->f_type == DTYPE_VNODE && 2328 (((struct vnode *)fp->f_data)->v_flag & VMAYHAVELOCKS) 2329 ) { 2330 lf.l_whence = SEEK_SET; 2331 lf.l_start = 0; 2332 lf.l_len = 0; 2333 lf.l_type = F_UNLCK; 2334 vp = (struct vnode *)fp->f_data; 2335 (void) VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, 0); 2336 } 2337 if (fp->f_ops != &badfileops) 2338 error = fo_close(fp); 2339 else 2340 error = 0; 2341 ffree(fp); 2342 rel_mplock(); 2343 return (error); 2344 } 2345 2346 /* 2347 * Apply an advisory lock on a file descriptor. 2348 * 2349 * Just attempt to get a record lock of the requested type on 2350 * the entire file (l_whence = SEEK_SET, l_start = 0, l_len = 0). 2351 */ 2352 int 2353 sys_flock(struct flock_args *uap) 2354 { 2355 struct proc *p = curproc; 2356 struct file *fp; 2357 struct vnode *vp; 2358 struct flock lf; 2359 int error; 2360 2361 if ((fp = holdfp(p->p_fd, uap->fd, -1)) == NULL) 2362 return (EBADF); 2363 if (fp->f_type != DTYPE_VNODE) { 2364 error = EOPNOTSUPP; 2365 goto done; 2366 } 2367 vp = (struct vnode *)fp->f_data; 2368 lf.l_whence = SEEK_SET; 2369 lf.l_start = 0; 2370 lf.l_len = 0; 2371 if (uap->how & LOCK_UN) { 2372 lf.l_type = F_UNLCK; 2373 fp->f_flag &= ~FHASLOCK; 2374 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, 0); 2375 goto done; 2376 } 2377 if (uap->how & LOCK_EX) 2378 lf.l_type = F_WRLCK; 2379 else if (uap->how & LOCK_SH) 2380 lf.l_type = F_RDLCK; 2381 else { 2382 error = EBADF; 2383 goto done; 2384 } 2385 fp->f_flag |= FHASLOCK; 2386 if (uap->how & LOCK_NB) 2387 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, 0); 2388 else 2389 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, F_WAIT); 2390 done: 2391 fdrop(fp); 2392 return (error); 2393 } 2394 2395 /* 2396 * File Descriptor pseudo-device driver (/dev/fd/). 2397 * 2398 * Opening minor device N dup()s the file (if any) connected to file 2399 * descriptor N belonging to the calling process. Note that this driver 2400 * consists of only the ``open()'' routine, because all subsequent 2401 * references to this file will be direct to the other driver. 2402 */ 2403 /* ARGSUSED */ 2404 static int 2405 fdopen(struct dev_open_args *ap) 2406 { 2407 thread_t td = curthread; 2408 2409 KKASSERT(td->td_lwp != NULL); 2410 2411 /* 2412 * XXX Kludge: set curlwp->lwp_dupfd to contain the value of the 2413 * the file descriptor being sought for duplication. The error 2414 * return ensures that the vnode for this device will be released 2415 * by vn_open. Open will detect this special error and take the 2416 * actions in dupfdopen below. Other callers of vn_open or VOP_OPEN 2417 * will simply report the error. 2418 */ 2419 td->td_lwp->lwp_dupfd = minor(ap->a_head.a_dev); 2420 return (ENODEV); 2421 } 2422 2423 /* 2424 * The caller has reserved the file descriptor dfd for us. On success we 2425 * must fsetfd() it. On failure the caller will clean it up. 2426 * 2427 * NOT MPSAFE - isn't getting spinlocks, possibly other things 2428 */ 2429 int 2430 dupfdopen(struct proc *p, int dfd, int sfd, int mode, int error) 2431 { 2432 struct filedesc *fdp = p->p_fd; 2433 struct file *wfp; 2434 struct file *xfp; 2435 int werror; 2436 2437 if ((wfp = holdfp(fdp, sfd, -1)) == NULL) 2438 return (EBADF); 2439 2440 /* 2441 * Close a revoke/dup race. Duping a descriptor marked as revoked 2442 * will dup a dummy descriptor instead of the real one. 2443 */ 2444 if (wfp->f_flag & FREVOKED) { 2445 kprintf("Warning: attempt to dup() a revoked descriptor\n"); 2446 fdrop(wfp); 2447 wfp = NULL; 2448 werror = falloc(NULL, &wfp, NULL); 2449 if (werror) 2450 return (werror); 2451 } 2452 2453 /* 2454 * There are two cases of interest here. 2455 * 2456 * For ENODEV simply dup sfd to file descriptor dfd and return. 2457 * 2458 * For ENXIO steal away the file structure from sfd and store it 2459 * dfd. sfd is effectively closed by this operation. 2460 * 2461 * Any other error code is just returned. 2462 */ 2463 switch (error) { 2464 case ENODEV: 2465 /* 2466 * Check that the mode the file is being opened for is a 2467 * subset of the mode of the existing descriptor. 2468 */ 2469 if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag) { 2470 error = EACCES; 2471 break; 2472 } 2473 fdp->fd_files[dfd].fileflags = fdp->fd_files[sfd].fileflags; 2474 fsetfd(p, wfp, dfd); 2475 error = 0; 2476 break; 2477 case ENXIO: 2478 /* 2479 * Steal away the file pointer from dfd, and stuff it into indx. 2480 */ 2481 fdp->fd_files[dfd].fileflags = fdp->fd_files[sfd].fileflags; 2482 fsetfd(p, wfp, dfd); 2483 if ((xfp = funsetfd_locked(fdp, sfd)) != NULL) 2484 fdrop(xfp); 2485 error = 0; 2486 break; 2487 default: 2488 break; 2489 } 2490 fdrop(wfp); 2491 return (error); 2492 } 2493 2494 /* 2495 * NOT MPSAFE - I think these refer to a common file descriptor table 2496 * and we need to spinlock that to link fdtol in. 2497 */ 2498 struct filedesc_to_leader * 2499 filedesc_to_leader_alloc(struct filedesc_to_leader *old, 2500 struct proc *leader) 2501 { 2502 struct filedesc_to_leader *fdtol; 2503 2504 fdtol = kmalloc(sizeof(struct filedesc_to_leader), 2505 M_FILEDESC_TO_LEADER, M_WAITOK); 2506 fdtol->fdl_refcount = 1; 2507 fdtol->fdl_holdcount = 0; 2508 fdtol->fdl_wakeup = 0; 2509 fdtol->fdl_leader = leader; 2510 if (old != NULL) { 2511 fdtol->fdl_next = old->fdl_next; 2512 fdtol->fdl_prev = old; 2513 old->fdl_next = fdtol; 2514 fdtol->fdl_next->fdl_prev = fdtol; 2515 } else { 2516 fdtol->fdl_next = fdtol; 2517 fdtol->fdl_prev = fdtol; 2518 } 2519 return fdtol; 2520 } 2521 2522 /* 2523 * Scan all file pointers in the system. The callback is made with 2524 * the master list spinlock held exclusively. 2525 * 2526 * MPSAFE 2527 */ 2528 void 2529 allfiles_scan_exclusive(int (*callback)(struct file *, void *), void *data) 2530 { 2531 struct file *fp; 2532 int res; 2533 2534 spin_lock_wr(&filehead_spin); 2535 LIST_FOREACH(fp, &filehead, f_list) { 2536 res = callback(fp, data); 2537 if (res < 0) 2538 break; 2539 } 2540 spin_unlock_wr(&filehead_spin); 2541 } 2542 2543 /* 2544 * Get file structures. 2545 * 2546 * NOT MPSAFE - process list scan, SYSCTL_OUT (probably not mpsafe) 2547 */ 2548 2549 struct sysctl_kern_file_info { 2550 int count; 2551 int error; 2552 struct sysctl_req *req; 2553 }; 2554 2555 static int sysctl_kern_file_callback(struct proc *p, void *data); 2556 2557 static int 2558 sysctl_kern_file(SYSCTL_HANDLER_ARGS) 2559 { 2560 struct sysctl_kern_file_info info; 2561 2562 /* 2563 * Note: because the number of file descriptors is calculated 2564 * in different ways for sizing vs returning the data, 2565 * there is information leakage from the first loop. However, 2566 * it is of a similar order of magnitude to the leakage from 2567 * global system statistics such as kern.openfiles. 2568 * 2569 * When just doing a count, note that we cannot just count 2570 * the elements and add f_count via the filehead list because 2571 * threaded processes share their descriptor table and f_count might 2572 * still be '1' in that case. 2573 * 2574 * Since the SYSCTL op can block, we must hold the process to 2575 * prevent it being ripped out from under us either in the 2576 * file descriptor loop or in the greater LIST_FOREACH. The 2577 * process may be in varying states of disrepair. If the process 2578 * is in SZOMB we may have caught it just as it is being removed 2579 * from the allproc list, we must skip it in that case to maintain 2580 * an unbroken chain through the allproc list. 2581 */ 2582 info.count = 0; 2583 info.error = 0; 2584 info.req = req; 2585 allproc_scan(sysctl_kern_file_callback, &info); 2586 2587 /* 2588 * When just calculating the size, overestimate a bit to try to 2589 * prevent system activity from causing the buffer-fill call 2590 * to fail later on. 2591 */ 2592 if (req->oldptr == NULL) { 2593 info.count = (info.count + 16) + (info.count / 10); 2594 info.error = SYSCTL_OUT(req, NULL, 2595 info.count * sizeof(struct kinfo_file)); 2596 } 2597 return (info.error); 2598 } 2599 2600 static int 2601 sysctl_kern_file_callback(struct proc *p, void *data) 2602 { 2603 struct sysctl_kern_file_info *info = data; 2604 struct kinfo_file kf; 2605 struct filedesc *fdp; 2606 struct file *fp; 2607 uid_t uid; 2608 int n; 2609 2610 if (p->p_stat == SIDL || p->p_stat == SZOMB) 2611 return(0); 2612 if (!PRISON_CHECK(info->req->td->td_proc->p_ucred, p->p_ucred) != 0) 2613 return(0); 2614 2615 /* 2616 * Softref the fdp to prevent it from being destroyed 2617 */ 2618 spin_lock_wr(&p->p_spin); 2619 if ((fdp = p->p_fd) == NULL) { 2620 spin_unlock_wr(&p->p_spin); 2621 return(0); 2622 } 2623 atomic_add_int(&fdp->fd_softrefs, 1); 2624 spin_unlock_wr(&p->p_spin); 2625 2626 /* 2627 * The fdp's own spinlock prevents the contents from being 2628 * modified. 2629 */ 2630 spin_lock_rd(&fdp->fd_spin); 2631 for (n = 0; n < fdp->fd_nfiles; ++n) { 2632 if ((fp = fdp->fd_files[n].fp) == NULL) 2633 continue; 2634 if (info->req->oldptr == NULL) { 2635 ++info->count; 2636 } else { 2637 uid = p->p_ucred ? p->p_ucred->cr_uid : -1; 2638 kcore_make_file(&kf, fp, p->p_pid, uid, n); 2639 spin_unlock_rd(&fdp->fd_spin); 2640 info->error = SYSCTL_OUT(info->req, &kf, sizeof(kf)); 2641 spin_lock_rd(&fdp->fd_spin); 2642 if (info->error) 2643 break; 2644 } 2645 } 2646 spin_unlock_rd(&fdp->fd_spin); 2647 atomic_subtract_int(&fdp->fd_softrefs, 1); 2648 if (info->error) 2649 return(-1); 2650 return(0); 2651 } 2652 2653 SYSCTL_PROC(_kern, KERN_FILE, file, CTLTYPE_OPAQUE|CTLFLAG_RD, 2654 0, 0, sysctl_kern_file, "S,file", "Entire file table"); 2655 2656 SYSCTL_INT(_kern, KERN_MAXFILESPERPROC, maxfilesperproc, CTLFLAG_RW, 2657 &maxfilesperproc, 0, "Maximum files allowed open per process"); 2658 2659 SYSCTL_INT(_kern, KERN_MAXFILES, maxfiles, CTLFLAG_RW, 2660 &maxfiles, 0, "Maximum number of files"); 2661 2662 SYSCTL_INT(_kern, OID_AUTO, maxfilesrootres, CTLFLAG_RW, 2663 &maxfilesrootres, 0, "Descriptors reserved for root use"); 2664 2665 SYSCTL_INT(_kern, OID_AUTO, openfiles, CTLFLAG_RD, 2666 &nfiles, 0, "System-wide number of open files"); 2667 2668 static void 2669 fildesc_drvinit(void *unused) 2670 { 2671 int fd; 2672 2673 dev_ops_add(&fildesc_ops, 0, 0); 2674 for (fd = 0; fd < NUMFDESC; fd++) { 2675 make_dev(&fildesc_ops, fd, 2676 UID_BIN, GID_BIN, 0666, "fd/%d", fd); 2677 } 2678 make_dev(&fildesc_ops, 0, UID_ROOT, GID_WHEEL, 0666, "stdin"); 2679 make_dev(&fildesc_ops, 1, UID_ROOT, GID_WHEEL, 0666, "stdout"); 2680 make_dev(&fildesc_ops, 2, UID_ROOT, GID_WHEEL, 0666, "stderr"); 2681 } 2682 2683 /* 2684 * MPSAFE 2685 */ 2686 struct fileops badfileops = { 2687 .fo_read = badfo_readwrite, 2688 .fo_write = badfo_readwrite, 2689 .fo_ioctl = badfo_ioctl, 2690 .fo_poll = badfo_poll, 2691 .fo_kqfilter = badfo_kqfilter, 2692 .fo_stat = badfo_stat, 2693 .fo_close = badfo_close, 2694 .fo_shutdown = badfo_shutdown 2695 }; 2696 2697 /* 2698 * MPSAFE 2699 */ 2700 static int 2701 badfo_readwrite( 2702 struct file *fp, 2703 struct uio *uio, 2704 struct ucred *cred, 2705 int flags 2706 ) { 2707 return (EBADF); 2708 } 2709 2710 /* 2711 * MPSAFE 2712 */ 2713 static int 2714 badfo_ioctl(struct file *fp, u_long com, caddr_t data, struct ucred *cred) 2715 { 2716 return (EBADF); 2717 } 2718 2719 /* 2720 * MPSAFE 2721 */ 2722 static int 2723 badfo_poll(struct file *fp, int events, struct ucred *cred) 2724 { 2725 return (0); 2726 } 2727 2728 /* 2729 * MPSAFE 2730 */ 2731 static int 2732 badfo_kqfilter(struct file *fp, struct knote *kn) 2733 { 2734 return (0); 2735 } 2736 2737 static int 2738 badfo_stat(struct file *fp, struct stat *sb, struct ucred *cred) 2739 { 2740 return (EBADF); 2741 } 2742 2743 /* 2744 * MPSAFE 2745 */ 2746 static int 2747 badfo_close(struct file *fp) 2748 { 2749 return (EBADF); 2750 } 2751 2752 /* 2753 * MPSAFE 2754 */ 2755 static int 2756 badfo_shutdown(struct file *fp, int how) 2757 { 2758 return (EBADF); 2759 } 2760 2761 /* 2762 * MPSAFE 2763 */ 2764 int 2765 nofo_shutdown(struct file *fp, int how) 2766 { 2767 return (EOPNOTSUPP); 2768 } 2769 2770 SYSINIT(fildescdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR, 2771 fildesc_drvinit,NULL) 2772