uipc_usrreq.c revision 3308
1/* 2 * Copyright (c) 1982, 1986, 1989, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)uipc_usrreq.c 8.3 (Berkeley) 1/4/94 34 * $Id: uipc_usrreq.c,v 1.4 1994/09/28 19:55:10 phk Exp $ 35 */ 36 37#include <sys/param.h> 38#include <sys/systm.h> 39#include <sys/proc.h> 40#include <sys/filedesc.h> 41#include <sys/domain.h> 42#include <sys/protosw.h> 43#include <sys/stat.h> 44#include <sys/socket.h> 45#include <sys/socketvar.h> 46#include <sys/unpcb.h> 47#include <sys/un.h> 48#include <sys/namei.h> 49#include <sys/vnode.h> 50#include <sys/file.h> 51#include <sys/stat.h> 52#include <sys/mbuf.h> 53 54/* 55 * Unix communications domain. 56 * 57 * TODO: 58 * SEQPACKET, RDM 59 * rethink name space problems 60 * need a proper out-of-band 61 */ 62struct sockaddr sun_noname = { sizeof(sun_noname), AF_UNIX }; 63ino_t unp_ino; /* prototype for fake inode numbers */ 64 65/*ARGSUSED*/ 66int 67uipc_usrreq(so, req, m, nam, control) 68 struct socket *so; 69 int req; 70 struct mbuf *m, *nam, *control; 71{ 72 struct unpcb *unp = sotounpcb(so); 73 register struct socket *so2; 74 register int error = 0; 75 struct proc *p = curproc; /* XXX */ 76 77 if (req == PRU_CONTROL) 78 return (EOPNOTSUPP); 79 if (req != PRU_SEND && control && control->m_len) { 80 error = EOPNOTSUPP; 81 goto release; 82 } 83 if (unp == 0 && req != PRU_ATTACH) { 84 error = EINVAL; 85 goto release; 86 } 87 switch (req) { 88 89 case PRU_ATTACH: 90 if (unp) { 91 error = EISCONN; 92 break; 93 } 94 error = unp_attach(so); 95 break; 96 97 case PRU_DETACH: 98 unp_detach(unp); 99 break; 100 101 case PRU_BIND: 102 error = unp_bind(unp, nam, p); 103 break; 104 105 case PRU_LISTEN: 106 if (unp->unp_vnode == 0) 107 error = EINVAL; 108 break; 109 110 case PRU_CONNECT: 111 error = unp_connect(so, nam, p); 112 break; 113 114 case PRU_CONNECT2: 115 error = unp_connect2(so, (struct socket *)nam); 116 break; 117 118 case PRU_DISCONNECT: 119 unp_disconnect(unp); 120 break; 121 122 case PRU_ACCEPT: 123 /* 124 * Pass back name of connected socket, 125 * if it was bound and we are still connected 126 * (our peer may have closed already!). 127 */ 128 if (unp->unp_conn && unp->unp_conn->unp_addr) { 129 nam->m_len = unp->unp_conn->unp_addr->m_len; 130 bcopy(mtod(unp->unp_conn->unp_addr, caddr_t), 131 mtod(nam, caddr_t), (unsigned)nam->m_len); 132 } else { 133 nam->m_len = sizeof(sun_noname); 134 *(mtod(nam, struct sockaddr *)) = sun_noname; 135 } 136 break; 137 138 case PRU_SHUTDOWN: 139 socantsendmore(so); 140 unp_shutdown(unp); 141 break; 142 143 case PRU_RCVD: 144 switch (so->so_type) { 145 146 case SOCK_DGRAM: 147 panic("uipc 1"); 148 /*NOTREACHED*/ 149 150 case SOCK_STREAM: 151#define rcv (&so->so_rcv) 152#define snd (&so2->so_snd) 153 if (unp->unp_conn == 0) 154 break; 155 so2 = unp->unp_conn->unp_socket; 156 /* 157 * Adjust backpressure on sender 158 * and wakeup any waiting to write. 159 */ 160 snd->sb_mbmax += unp->unp_mbcnt - rcv->sb_mbcnt; 161 unp->unp_mbcnt = rcv->sb_mbcnt; 162 snd->sb_hiwat += unp->unp_cc - rcv->sb_cc; 163 unp->unp_cc = rcv->sb_cc; 164 sowwakeup(so2); 165#undef snd 166#undef rcv 167 break; 168 169 default: 170 panic("uipc 2"); 171 } 172 break; 173 174 case PRU_SEND: 175 if (control && (error = unp_internalize(control, p))) 176 break; 177 switch (so->so_type) { 178 179 case SOCK_DGRAM: { 180 struct sockaddr *from; 181 182 if (nam) { 183 if (unp->unp_conn) { 184 error = EISCONN; 185 break; 186 } 187 error = unp_connect(so, nam, p); 188 if (error) 189 break; 190 } else { 191 if (unp->unp_conn == 0) { 192 error = ENOTCONN; 193 break; 194 } 195 } 196 so2 = unp->unp_conn->unp_socket; 197 if (unp->unp_addr) 198 from = mtod(unp->unp_addr, struct sockaddr *); 199 else 200 from = &sun_noname; 201 if (sbappendaddr(&so2->so_rcv, from, m, control)) { 202 sorwakeup(so2); 203 m = 0; 204 control = 0; 205 } else 206 error = ENOBUFS; 207 if (nam) 208 unp_disconnect(unp); 209 break; 210 } 211 212 case SOCK_STREAM: 213#define rcv (&so2->so_rcv) 214#define snd (&so->so_snd) 215 if (so->so_state & SS_CANTSENDMORE) { 216 error = EPIPE; 217 break; 218 } 219 if (unp->unp_conn == 0) 220 panic("uipc 3"); 221 so2 = unp->unp_conn->unp_socket; 222 /* 223 * Send to paired receive port, and then reduce 224 * send buffer hiwater marks to maintain backpressure. 225 * Wake up readers. 226 */ 227 if (control) { 228 if (sbappendcontrol(rcv, m, control)) 229 control = 0; 230 } else 231 sbappend(rcv, m); 232 snd->sb_mbmax -= 233 rcv->sb_mbcnt - unp->unp_conn->unp_mbcnt; 234 unp->unp_conn->unp_mbcnt = rcv->sb_mbcnt; 235 snd->sb_hiwat -= rcv->sb_cc - unp->unp_conn->unp_cc; 236 unp->unp_conn->unp_cc = rcv->sb_cc; 237 sorwakeup(so2); 238 m = 0; 239#undef snd 240#undef rcv 241 break; 242 243 default: 244 panic("uipc 4"); 245 } 246 break; 247 248 case PRU_ABORT: 249 unp_drop(unp, ECONNABORTED); 250 break; 251 252 case PRU_SENSE: 253 ((struct stat *) m)->st_blksize = so->so_snd.sb_hiwat; 254 if (so->so_type == SOCK_STREAM && unp->unp_conn != 0) { 255 so2 = unp->unp_conn->unp_socket; 256 ((struct stat *) m)->st_blksize += so2->so_rcv.sb_cc; 257 } 258 ((struct stat *) m)->st_dev = NODEV; 259 if (unp->unp_ino == 0) 260 unp->unp_ino = unp_ino++; 261 ((struct stat *) m)->st_ino = unp->unp_ino; 262 return (0); 263 264 case PRU_RCVOOB: 265 return (EOPNOTSUPP); 266 267 case PRU_SENDOOB: 268 error = EOPNOTSUPP; 269 break; 270 271 case PRU_SOCKADDR: 272 if (unp->unp_addr) { 273 nam->m_len = unp->unp_addr->m_len; 274 bcopy(mtod(unp->unp_addr, caddr_t), 275 mtod(nam, caddr_t), (unsigned)nam->m_len); 276 } else 277 nam->m_len = 0; 278 break; 279 280 case PRU_PEERADDR: 281 if (unp->unp_conn && unp->unp_conn->unp_addr) { 282 nam->m_len = unp->unp_conn->unp_addr->m_len; 283 bcopy(mtod(unp->unp_conn->unp_addr, caddr_t), 284 mtod(nam, caddr_t), (unsigned)nam->m_len); 285 } else 286 nam->m_len = 0; 287 break; 288 289 case PRU_SLOWTIMO: 290 break; 291 292 default: 293 panic("piusrreq"); 294 } 295release: 296 if (control) 297 m_freem(control); 298 if (m) 299 m_freem(m); 300 return (error); 301} 302 303/* 304 * Both send and receive buffers are allocated PIPSIZ bytes of buffering 305 * for stream sockets, although the total for sender and receiver is 306 * actually only PIPSIZ. 307 * Datagram sockets really use the sendspace as the maximum datagram size, 308 * and don't really want to reserve the sendspace. Their recvspace should 309 * be large enough for at least one max-size datagram plus address. 310 */ 311#define PIPSIZ 4096 312u_long unpst_sendspace = PIPSIZ; 313u_long unpst_recvspace = PIPSIZ; 314u_long unpdg_sendspace = 2*1024; /* really max datagram size */ 315u_long unpdg_recvspace = 4*1024; 316 317int unp_rights; /* file descriptors in flight */ 318 319int 320unp_attach(so) 321 struct socket *so; 322{ 323 register struct mbuf *m; 324 register struct unpcb *unp; 325 int error; 326 327 if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) { 328 switch (so->so_type) { 329 330 case SOCK_STREAM: 331 error = soreserve(so, unpst_sendspace, unpst_recvspace); 332 break; 333 334 case SOCK_DGRAM: 335 error = soreserve(so, unpdg_sendspace, unpdg_recvspace); 336 break; 337 338 default: 339 panic("unp_attach"); 340 } 341 if (error) 342 return (error); 343 } 344 m = m_getclr(M_DONTWAIT, MT_PCB); 345 if (m == NULL) 346 return (ENOBUFS); 347 unp = mtod(m, struct unpcb *); 348 so->so_pcb = (caddr_t)unp; 349 unp->unp_socket = so; 350 return (0); 351} 352 353void 354unp_detach(unp) 355 register struct unpcb *unp; 356{ 357 358 if (unp->unp_vnode) { 359 unp->unp_vnode->v_socket = 0; 360 vrele(unp->unp_vnode); 361 unp->unp_vnode = 0; 362 } 363 if (unp->unp_conn) 364 unp_disconnect(unp); 365 while (unp->unp_refs) 366 unp_drop(unp->unp_refs, ECONNRESET); 367 soisdisconnected(unp->unp_socket); 368 unp->unp_socket->so_pcb = 0; 369 m_freem(unp->unp_addr); 370 (void) m_free(dtom(unp)); 371 if (unp_rights) { 372 /* 373 * Normally the receive buffer is flushed later, 374 * in sofree, but if our receive buffer holds references 375 * to descriptors that are now garbage, we will dispose 376 * of those descriptor references after the garbage collector 377 * gets them (resulting in a "panic: closef: count < 0"). 378 */ 379 sorflush(unp->unp_socket); 380 unp_gc(); 381 } 382} 383 384int 385unp_bind(unp, nam, p) 386 struct unpcb *unp; 387 struct mbuf *nam; 388 struct proc *p; 389{ 390 struct sockaddr_un *soun = mtod(nam, struct sockaddr_un *); 391 register struct vnode *vp; 392 struct vattr vattr; 393 int error; 394 struct nameidata nd; 395 396 NDINIT(&nd, CREATE, FOLLOW | LOCKPARENT, UIO_SYSSPACE, 397 soun->sun_path, p); 398 if (unp->unp_vnode != NULL) 399 return (EINVAL); 400 if (nam->m_len == MLEN) { 401 if (*(mtod(nam, caddr_t) + nam->m_len - 1) != 0) 402 return (EINVAL); 403 } else 404 *(mtod(nam, caddr_t) + nam->m_len) = 0; 405/* SHOULD BE ABLE TO ADOPT EXISTING AND wakeup() ALA FIFO's */ 406 error = namei(&nd); 407 if (error) 408 return (error); 409 vp = nd.ni_vp; 410 if (vp != NULL) { 411 VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd); 412 if (nd.ni_dvp == vp) 413 vrele(nd.ni_dvp); 414 else 415 vput(nd.ni_dvp); 416 vrele(vp); 417 return (EADDRINUSE); 418 } 419 VATTR_NULL(&vattr); 420 vattr.va_type = VSOCK; 421 vattr.va_mode = ACCESSPERMS; 422 LEASE_CHECK(nd.ni_dvp, p, p->p_ucred, LEASE_WRITE); 423 error = VOP_CREATE(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &vattr); 424 if (error) 425 return (error); 426 vp = nd.ni_vp; 427 vp->v_socket = unp->unp_socket; 428 unp->unp_vnode = vp; 429 unp->unp_addr = m_copy(nam, 0, (int)M_COPYALL); 430 VOP_UNLOCK(vp); 431 return (0); 432} 433 434int 435unp_connect(so, nam, p) 436 struct socket *so; 437 struct mbuf *nam; 438 struct proc *p; 439{ 440 register struct sockaddr_un *soun = mtod(nam, struct sockaddr_un *); 441 register struct vnode *vp; 442 register struct socket *so2, *so3; 443 struct unpcb *unp2, *unp3; 444 int error; 445 struct nameidata nd; 446 447 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, soun->sun_path, p); 448 if (nam->m_data + nam->m_len == &nam->m_dat[MLEN]) { /* XXX */ 449 if (*(mtod(nam, caddr_t) + nam->m_len - 1) != 0) 450 return (EMSGSIZE); 451 } else 452 *(mtod(nam, caddr_t) + nam->m_len) = 0; 453 error = namei(&nd); 454 if (error) 455 return (error); 456 vp = nd.ni_vp; 457 if (vp->v_type != VSOCK) { 458 error = ENOTSOCK; 459 goto bad; 460 } 461 error = VOP_ACCESS(vp, VWRITE, p->p_ucred, p); 462 if (error) 463 goto bad; 464 so2 = vp->v_socket; 465 if (so2 == 0) { 466 error = ECONNREFUSED; 467 goto bad; 468 } 469 if (so->so_type != so2->so_type) { 470 error = EPROTOTYPE; 471 goto bad; 472 } 473 if (so->so_proto->pr_flags & PR_CONNREQUIRED) { 474 if ((so2->so_options & SO_ACCEPTCONN) == 0 || 475 (so3 = sonewconn(so2, 0)) == 0) { 476 error = ECONNREFUSED; 477 goto bad; 478 } 479 unp2 = sotounpcb(so2); 480 unp3 = sotounpcb(so3); 481 if (unp2->unp_addr) 482 unp3->unp_addr = 483 m_copy(unp2->unp_addr, 0, (int)M_COPYALL); 484 so2 = so3; 485 } 486 error = unp_connect2(so, so2); 487bad: 488 vput(vp); 489 return (error); 490} 491 492int 493unp_connect2(so, so2) 494 register struct socket *so; 495 register struct socket *so2; 496{ 497 register struct unpcb *unp = sotounpcb(so); 498 register struct unpcb *unp2; 499 500 if (so2->so_type != so->so_type) 501 return (EPROTOTYPE); 502 unp2 = sotounpcb(so2); 503 unp->unp_conn = unp2; 504 switch (so->so_type) { 505 506 case SOCK_DGRAM: 507 unp->unp_nextref = unp2->unp_refs; 508 unp2->unp_refs = unp; 509 soisconnected(so); 510 break; 511 512 case SOCK_STREAM: 513 unp2->unp_conn = unp; 514 soisconnected(so); 515 soisconnected(so2); 516 break; 517 518 default: 519 panic("unp_connect2"); 520 } 521 return (0); 522} 523 524void 525unp_disconnect(unp) 526 struct unpcb *unp; 527{ 528 register struct unpcb *unp2 = unp->unp_conn; 529 530 if (unp2 == 0) 531 return; 532 unp->unp_conn = 0; 533 switch (unp->unp_socket->so_type) { 534 535 case SOCK_DGRAM: 536 if (unp2->unp_refs == unp) 537 unp2->unp_refs = unp->unp_nextref; 538 else { 539 unp2 = unp2->unp_refs; 540 for (;;) { 541 if (unp2 == 0) 542 panic("unp_disconnect"); 543 if (unp2->unp_nextref == unp) 544 break; 545 unp2 = unp2->unp_nextref; 546 } 547 unp2->unp_nextref = unp->unp_nextref; 548 } 549 unp->unp_nextref = 0; 550 unp->unp_socket->so_state &= ~SS_ISCONNECTED; 551 break; 552 553 case SOCK_STREAM: 554 soisdisconnected(unp->unp_socket); 555 unp2->unp_conn = 0; 556 soisdisconnected(unp2->unp_socket); 557 break; 558 } 559} 560 561#ifdef notdef 562void 563unp_abort(unp) 564 struct unpcb *unp; 565{ 566 567 unp_detach(unp); 568} 569#endif 570 571void 572unp_shutdown(unp) 573 struct unpcb *unp; 574{ 575 struct socket *so; 576 577 if (unp->unp_socket->so_type == SOCK_STREAM && unp->unp_conn && 578 (so = unp->unp_conn->unp_socket)) 579 socantrcvmore(so); 580} 581 582void 583unp_drop(unp, errno) 584 struct unpcb *unp; 585 int errno; 586{ 587 struct socket *so = unp->unp_socket; 588 589 so->so_error = errno; 590 unp_disconnect(unp); 591 if (so->so_head) { 592 so->so_pcb = (caddr_t) 0; 593 m_freem(unp->unp_addr); 594 (void) m_free(dtom(unp)); 595 sofree(so); 596 } 597} 598 599#ifdef notdef 600void 601unp_drain() 602{ 603 604} 605#endif 606 607int 608unp_externalize(rights) 609 struct mbuf *rights; 610{ 611 struct proc *p = curproc; /* XXX */ 612 register int i; 613 register struct cmsghdr *cm = mtod(rights, struct cmsghdr *); 614 register struct file **rp = (struct file **)(cm + 1); 615 register struct file *fp; 616 int newfds = (cm->cmsg_len - sizeof(*cm)) / sizeof (int); 617 int f; 618 619 if (!fdavail(p, newfds)) { 620 for (i = 0; i < newfds; i++) { 621 fp = *rp; 622 unp_discard(fp); 623 *rp++ = 0; 624 } 625 return (EMSGSIZE); 626 } 627 for (i = 0; i < newfds; i++) { 628 if (fdalloc(p, 0, &f)) 629 panic("unp_externalize"); 630 fp = *rp; 631 p->p_fd->fd_ofiles[f] = fp; 632 fp->f_msgcount--; 633 unp_rights--; 634 *(int *)rp++ = f; 635 } 636 return (0); 637} 638 639int 640unp_internalize(control, p) 641 struct mbuf *control; 642 struct proc *p; 643{ 644 struct filedesc *fdp = p->p_fd; 645 register struct cmsghdr *cm = mtod(control, struct cmsghdr *); 646 register struct file **rp; 647 register struct file *fp; 648 register int i, fd; 649 int oldfds; 650 651 if (cm->cmsg_type != SCM_RIGHTS || cm->cmsg_level != SOL_SOCKET || 652 cm->cmsg_len != control->m_len) 653 return (EINVAL); 654 oldfds = (cm->cmsg_len - sizeof (*cm)) / sizeof (int); 655 rp = (struct file **)(cm + 1); 656 for (i = 0; i < oldfds; i++) { 657 fd = *(int *)rp++; 658 if ((unsigned)fd >= fdp->fd_nfiles || 659 fdp->fd_ofiles[fd] == NULL) 660 return (EBADF); 661 } 662 rp = (struct file **)(cm + 1); 663 for (i = 0; i < oldfds; i++) { 664 fp = fdp->fd_ofiles[*(int *)rp]; 665 *rp++ = fp; 666 fp->f_count++; 667 fp->f_msgcount++; 668 unp_rights++; 669 } 670 return (0); 671} 672 673int unp_defer, unp_gcing; 674extern struct domain unixdomain; 675 676void 677unp_gc() 678{ 679 register struct file *fp, *nextfp; 680 register struct socket *so; 681 struct file **extra_ref, **fpp; 682 int nunref, i; 683 684 if (unp_gcing) 685 return; 686 unp_gcing = 1; 687 unp_defer = 0; 688 for (fp = filehead; fp; fp = fp->f_filef) 689 fp->f_flag &= ~(FMARK|FDEFER); 690 do { 691 for (fp = filehead; fp; fp = fp->f_filef) { 692 if (fp->f_count == 0) 693 continue; 694 if (fp->f_flag & FDEFER) { 695 fp->f_flag &= ~FDEFER; 696 unp_defer--; 697 } else { 698 if (fp->f_flag & FMARK) 699 continue; 700 if (fp->f_count == fp->f_msgcount) 701 continue; 702 fp->f_flag |= FMARK; 703 } 704 if (fp->f_type != DTYPE_SOCKET || 705 (so = (struct socket *)fp->f_data) == 0) 706 continue; 707 if (so->so_proto->pr_domain != &unixdomain || 708 (so->so_proto->pr_flags&PR_RIGHTS) == 0) 709 continue; 710#ifdef notdef 711 if (so->so_rcv.sb_flags & SB_LOCK) { 712 /* 713 * This is problematical; it's not clear 714 * we need to wait for the sockbuf to be 715 * unlocked (on a uniprocessor, at least), 716 * and it's also not clear what to do 717 * if sbwait returns an error due to receipt 718 * of a signal. If sbwait does return 719 * an error, we'll go into an infinite 720 * loop. Delete all of this for now. 721 */ 722 (void) sbwait(&so->so_rcv); 723 goto restart; 724 } 725#endif 726 unp_scan(so->so_rcv.sb_mb, unp_mark); 727 } 728 } while (unp_defer); 729 /* 730 * We grab an extra reference to each of the file table entries 731 * that are not otherwise accessible and then free the rights 732 * that are stored in messages on them. 733 * 734 * The bug in the orginal code is a little tricky, so I'll describe 735 * what's wrong with it here. 736 * 737 * It is incorrect to simply unp_discard each entry for f_msgcount 738 * times -- consider the case of sockets A and B that contain 739 * references to each other. On a last close of some other socket, 740 * we trigger a gc since the number of outstanding rights (unp_rights) 741 * is non-zero. If during the sweep phase the gc code un_discards, 742 * we end up doing a (full) closef on the descriptor. A closef on A 743 * results in the following chain. Closef calls soo_close, which 744 * calls soclose. Soclose calls first (through the switch 745 * uipc_usrreq) unp_detach, which re-invokes unp_gc. Unp_gc simply 746 * returns because the previous instance had set unp_gcing, and 747 * we return all the way back to soclose, which marks the socket 748 * with SS_NOFDREF, and then calls sofree. Sofree calls sorflush 749 * to free up the rights that are queued in messages on the socket A, 750 * i.e., the reference on B. The sorflush calls via the dom_dispose 751 * switch unp_dispose, which unp_scans with unp_discard. This second 752 * instance of unp_discard just calls closef on B. 753 * 754 * Well, a similar chain occurs on B, resulting in a sorflush on B, 755 * which results in another closef on A. Unfortunately, A is already 756 * being closed, and the descriptor has already been marked with 757 * SS_NOFDREF, and soclose panics at this point. 758 * 759 * Here, we first take an extra reference to each inaccessible 760 * descriptor. Then, we call sorflush ourself, since we know 761 * it is a Unix domain socket anyhow. After we destroy all the 762 * rights carried in messages, we do a last closef to get rid 763 * of our extra reference. This is the last close, and the 764 * unp_detach etc will shut down the socket. 765 * 766 * 91/09/19, bsy@cs.cmu.edu 767 */ 768 extra_ref = malloc(nfiles * sizeof(struct file *), M_FILE, M_WAITOK); 769 for (nunref = 0, fp = filehead, fpp = extra_ref; fp; fp = nextfp) { 770 nextfp = fp->f_filef; 771 if (fp->f_count == 0) 772 continue; 773 if (fp->f_count == fp->f_msgcount && !(fp->f_flag & FMARK)) { 774 *fpp++ = fp; 775 nunref++; 776 fp->f_count++; 777 } 778 } 779 for (i = nunref, fpp = extra_ref; --i >= 0; ++fpp) 780 sorflush((struct socket *)(*fpp)->f_data); 781 for (i = nunref, fpp = extra_ref; --i >= 0; ++fpp) 782 closef(*fpp,(struct proc*) NULL); 783 free((caddr_t)extra_ref, M_FILE); 784 unp_gcing = 0; 785} 786 787void 788unp_dispose(m) 789 struct mbuf *m; 790{ 791 if (m) 792 unp_scan(m, unp_discard); 793} 794 795void 796unp_scan(m0, op) 797 register struct mbuf *m0; 798 void (*op)(struct file *); 799{ 800 register struct mbuf *m; 801 register struct file **rp; 802 register struct cmsghdr *cm; 803 register int i; 804 int qfds; 805 806 while (m0) { 807 for (m = m0; m; m = m->m_next) 808 if (m->m_type == MT_CONTROL && 809 m->m_len >= sizeof(*cm)) { 810 cm = mtod(m, struct cmsghdr *); 811 if (cm->cmsg_level != SOL_SOCKET || 812 cm->cmsg_type != SCM_RIGHTS) 813 continue; 814 qfds = (cm->cmsg_len - sizeof *cm) 815 / sizeof (struct file *); 816 rp = (struct file **)(cm + 1); 817 for (i = 0; i < qfds; i++) 818 (*op)(*rp++); 819 break; /* XXX, but saves time */ 820 } 821 m0 = m0->m_act; 822 } 823} 824 825void 826unp_mark(fp) 827 struct file *fp; 828{ 829 830 if (fp->f_flag & FMARK) 831 return; 832 unp_defer++; 833 fp->f_flag |= (FMARK|FDEFER); 834} 835 836void 837unp_discard(fp) 838 struct file *fp; 839{ 840 841 fp->f_msgcount--; 842 unp_rights--; 843 (void) closef(fp, (struct proc *)NULL); 844} 845