uipc_usrreq.c revision 22975
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 * From: @(#)uipc_usrreq.c 8.3 (Berkeley) 1/4/94 34 * $Id$ 35 */ 36 37#include <sys/param.h> 38#include <sys/queue.h> 39#include <sys/systm.h> 40#include <sys/proc.h> 41#include <sys/filedesc.h> 42#include <sys/domain.h> 43#include <sys/protosw.h> 44#include <sys/stat.h> 45#include <sys/socket.h> 46#include <sys/socketvar.h> 47#include <sys/unpcb.h> 48#include <sys/un.h> 49#include <sys/namei.h> 50#include <sys/vnode.h> 51#include <sys/file.h> 52#include <sys/stat.h> 53#include <sys/mbuf.h> 54 55/* 56 * Unix communications domain. 57 * 58 * TODO: 59 * SEQPACKET, RDM 60 * rethink name space problems 61 * need a proper out-of-band 62 */ 63static struct sockaddr sun_noname = { sizeof(sun_noname), AF_LOCAL }; 64static ino_t unp_ino; /* prototype for fake inode numbers */ 65 66static int unp_attach __P((struct socket *)); 67static void unp_detach __P((struct unpcb *)); 68static int unp_bind __P((struct unpcb *,struct mbuf *, struct proc *)); 69static int unp_connect __P((struct socket *,struct mbuf *, struct proc *)); 70static void unp_disconnect __P((struct unpcb *)); 71static void unp_shutdown __P((struct unpcb *)); 72static void unp_drop __P((struct unpcb *, int)); 73static void unp_gc __P((void)); 74static void unp_scan __P((struct mbuf *, void (*)(struct file *))); 75static void unp_mark __P((struct file *)); 76static void unp_discard __P((struct file *)); 77static int unp_internalize __P((struct mbuf *, struct proc *)); 78 79 80/*ARGSUSED*/ 81int 82uipc_usrreq(so, req, m, nam, control) 83 struct socket *so; 84 int req; 85 struct mbuf *m, *nam, *control; 86{ 87 struct unpcb *unp = sotounpcb(so); 88 register struct socket *so2; 89 register int error = 0; 90 struct proc *p = curproc; /* XXX */ 91 92 if (req == PRU_CONTROL) 93 return (EOPNOTSUPP); 94 if (req != PRU_SEND && control && control->m_len) { 95 error = EOPNOTSUPP; 96 goto release; 97 } 98 if (unp == 0 && req != PRU_ATTACH) { 99 error = EINVAL; 100 goto release; 101 } 102 switch (req) { 103 104 case PRU_ATTACH: 105 if (unp) { 106 error = EISCONN; 107 break; 108 } 109 error = unp_attach(so); 110 break; 111 112 case PRU_DETACH: 113 unp_detach(unp); 114 break; 115 116 case PRU_BIND: 117 error = unp_bind(unp, nam, p); 118 break; 119 120 case PRU_LISTEN: 121 if (unp->unp_vnode == 0) 122 error = EINVAL; 123 break; 124 125 case PRU_CONNECT: 126 error = unp_connect(so, nam, p); 127 break; 128 129 case PRU_CONNECT2: 130 error = unp_connect2(so, (struct socket *)nam); 131 break; 132 133 case PRU_DISCONNECT: 134 unp_disconnect(unp); 135 break; 136 137 case PRU_ACCEPT: 138 /* 139 * Pass back name of connected socket, 140 * if it was bound and we are still connected 141 * (our peer may have closed already!). 142 */ 143 if (unp->unp_conn && unp->unp_conn->unp_addr) { 144 nam->m_len = unp->unp_conn->unp_addr->m_len; 145 bcopy(mtod(unp->unp_conn->unp_addr, caddr_t), 146 mtod(nam, caddr_t), (unsigned)nam->m_len); 147 } else { 148 nam->m_len = sizeof(sun_noname); 149 *(mtod(nam, struct sockaddr *)) = sun_noname; 150 } 151 break; 152 153 case PRU_SHUTDOWN: 154 socantsendmore(so); 155 unp_shutdown(unp); 156 break; 157 158 case PRU_RCVD: 159 switch (so->so_type) { 160 161 case SOCK_DGRAM: 162 panic("uipc 1"); 163 /*NOTREACHED*/ 164 165 case SOCK_STREAM: 166#define rcv (&so->so_rcv) 167#define snd (&so2->so_snd) 168 if (unp->unp_conn == 0) 169 break; 170 so2 = unp->unp_conn->unp_socket; 171 /* 172 * Adjust backpressure on sender 173 * and wakeup any waiting to write. 174 */ 175 snd->sb_mbmax += unp->unp_mbcnt - rcv->sb_mbcnt; 176 unp->unp_mbcnt = rcv->sb_mbcnt; 177 snd->sb_hiwat += unp->unp_cc - rcv->sb_cc; 178 unp->unp_cc = rcv->sb_cc; 179 sowwakeup(so2); 180#undef snd 181#undef rcv 182 break; 183 184 default: 185 panic("uipc 2"); 186 } 187 break; 188 189 case PRU_SEND: 190 case PRU_SEND_EOF: 191 if (control && (error = unp_internalize(control, p))) 192 break; 193 switch (so->so_type) { 194 195 case SOCK_DGRAM: { 196 struct sockaddr *from; 197 198 if (nam) { 199 if (unp->unp_conn) { 200 error = EISCONN; 201 break; 202 } 203 error = unp_connect(so, nam, p); 204 if (error) 205 break; 206 } else { 207 if (unp->unp_conn == 0) { 208 error = ENOTCONN; 209 break; 210 } 211 } 212 so2 = unp->unp_conn->unp_socket; 213 if (unp->unp_addr) 214 from = mtod(unp->unp_addr, struct sockaddr *); 215 else 216 from = &sun_noname; 217 if (sbappendaddr(&so2->so_rcv, from, m, control)) { 218 sorwakeup(so2); 219 m = 0; 220 control = 0; 221 } else 222 error = ENOBUFS; 223 if (nam) 224 unp_disconnect(unp); 225 break; 226 } 227 228 case SOCK_STREAM: 229#define rcv (&so2->so_rcv) 230#define snd (&so->so_snd) 231 /* Connect if not connected yet. */ 232 /* 233 * Note: A better implementation would complain 234 * if not equal to the peer's address. 235 */ 236 if ((so->so_state & SS_ISCONNECTED) == 0) { 237 if (nam) { 238 error = unp_connect(so, nam, p); 239 if (error) 240 break; /* XXX */ 241 } else { 242 error = ENOTCONN; 243 break; 244 } 245 } 246 247 if (so->so_state & SS_CANTSENDMORE) { 248 error = EPIPE; 249 break; 250 } 251 if (unp->unp_conn == 0) 252 panic("uipc 3"); 253 so2 = unp->unp_conn->unp_socket; 254 /* 255 * Send to paired receive port, and then reduce 256 * send buffer hiwater marks to maintain backpressure. 257 * Wake up readers. 258 */ 259 if (control) { 260 if (sbappendcontrol(rcv, m, control)) 261 control = 0; 262 } else 263 sbappend(rcv, m); 264 snd->sb_mbmax -= 265 rcv->sb_mbcnt - unp->unp_conn->unp_mbcnt; 266 unp->unp_conn->unp_mbcnt = rcv->sb_mbcnt; 267 snd->sb_hiwat -= rcv->sb_cc - unp->unp_conn->unp_cc; 268 unp->unp_conn->unp_cc = rcv->sb_cc; 269 sorwakeup(so2); 270 m = 0; 271#undef snd 272#undef rcv 273 break; 274 275 default: 276 panic("uipc 4"); 277 } 278 /* 279 * SEND_EOF is equivalent to a SEND followed by 280 * a SHUTDOWN. 281 */ 282 if (req == PRU_SEND_EOF) { 283 socantsendmore(so); 284 unp_shutdown(unp); 285 } 286 break; 287 288 case PRU_ABORT: 289 unp_drop(unp, ECONNABORTED); 290 break; 291 292 case PRU_SENSE: 293 ((struct stat *) m)->st_blksize = so->so_snd.sb_hiwat; 294 if (so->so_type == SOCK_STREAM && unp->unp_conn != 0) { 295 so2 = unp->unp_conn->unp_socket; 296 ((struct stat *) m)->st_blksize += so2->so_rcv.sb_cc; 297 } 298 ((struct stat *) m)->st_dev = NODEV; 299 if (unp->unp_ino == 0) 300 unp->unp_ino = unp_ino++; 301 ((struct stat *) m)->st_ino = unp->unp_ino; 302 return (0); 303 304 case PRU_RCVOOB: 305 return (EOPNOTSUPP); 306 307 case PRU_SENDOOB: 308 error = EOPNOTSUPP; 309 break; 310 311 case PRU_SOCKADDR: 312 if (unp->unp_addr) { 313 nam->m_len = unp->unp_addr->m_len; 314 bcopy(mtod(unp->unp_addr, caddr_t), 315 mtod(nam, caddr_t), (unsigned)nam->m_len); 316 } else 317 nam->m_len = 0; 318 break; 319 320 case PRU_PEERADDR: 321 if (unp->unp_conn && unp->unp_conn->unp_addr) { 322 nam->m_len = unp->unp_conn->unp_addr->m_len; 323 bcopy(mtod(unp->unp_conn->unp_addr, caddr_t), 324 mtod(nam, caddr_t), (unsigned)nam->m_len); 325 } else 326 nam->m_len = 0; 327 break; 328 329 case PRU_SLOWTIMO: 330 break; 331 332 default: 333 panic("piusrreq"); 334 } 335release: 336 if (control) 337 m_freem(control); 338 if (m) 339 m_freem(m); 340 return (error); 341} 342 343/* 344 * Both send and receive buffers are allocated PIPSIZ bytes of buffering 345 * for stream sockets, although the total for sender and receiver is 346 * actually only PIPSIZ. 347 * Datagram sockets really use the sendspace as the maximum datagram size, 348 * and don't really want to reserve the sendspace. Their recvspace should 349 * be large enough for at least one max-size datagram plus address. 350 */ 351#ifndef PIPSIZ 352#define PIPSIZ 8192 353#endif 354static u_long unpst_sendspace = PIPSIZ; 355static u_long unpst_recvspace = PIPSIZ; 356static u_long unpdg_sendspace = 2*1024; /* really max datagram size */ 357static u_long unpdg_recvspace = 4*1024; 358 359static int unp_rights; /* file descriptors in flight */ 360 361static int 362unp_attach(so) 363 struct socket *so; 364{ 365 register struct mbuf *m; 366 register struct unpcb *unp; 367 int error; 368 369 if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) { 370 switch (so->so_type) { 371 372 case SOCK_STREAM: 373 error = soreserve(so, unpst_sendspace, unpst_recvspace); 374 break; 375 376 case SOCK_DGRAM: 377 error = soreserve(so, unpdg_sendspace, unpdg_recvspace); 378 break; 379 380 default: 381 panic("unp_attach"); 382 } 383 if (error) 384 return (error); 385 } 386 m = m_getclr(M_DONTWAIT, MT_PCB); 387 if (m == NULL) 388 return (ENOBUFS); 389 unp = mtod(m, struct unpcb *); 390 so->so_pcb = (caddr_t)unp; 391 unp->unp_socket = so; 392 return (0); 393} 394 395static void 396unp_detach(unp) 397 register struct unpcb *unp; 398{ 399 400 if (unp->unp_vnode) { 401 unp->unp_vnode->v_socket = 0; 402 vrele(unp->unp_vnode); 403 unp->unp_vnode = 0; 404 } 405 if (unp->unp_conn) 406 unp_disconnect(unp); 407 while (unp->unp_refs) 408 unp_drop(unp->unp_refs, ECONNRESET); 409 soisdisconnected(unp->unp_socket); 410 unp->unp_socket->so_pcb = 0; 411 if (unp_rights) { 412 /* 413 * Normally the receive buffer is flushed later, 414 * in sofree, but if our receive buffer holds references 415 * to descriptors that are now garbage, we will dispose 416 * of those descriptor references after the garbage collector 417 * gets them (resulting in a "panic: closef: count < 0"). 418 */ 419 sorflush(unp->unp_socket); 420 unp_gc(); 421 } 422 m_freem(unp->unp_addr); 423 (void) m_free(dtom(unp)); 424} 425 426static int 427unp_bind(unp, nam, p) 428 struct unpcb *unp; 429 struct mbuf *nam; 430 struct proc *p; 431{ 432 struct sockaddr_un *soun = mtod(nam, struct sockaddr_un *); 433 register struct vnode *vp; 434 struct vattr vattr; 435 int error; 436 struct nameidata nd; 437 438 NDINIT(&nd, CREATE, FOLLOW | LOCKPARENT, UIO_SYSSPACE, 439 soun->sun_path, p); 440 if (unp->unp_vnode != NULL) 441 return (EINVAL); 442 if (nam->m_len == MLEN) { 443 if (*(mtod(nam, caddr_t) + nam->m_len - 1) != 0) 444 return (EINVAL); 445 } else 446 *(mtod(nam, caddr_t) + nam->m_len) = 0; 447/* SHOULD BE ABLE TO ADOPT EXISTING AND wakeup() ALA FIFO's */ 448 error = namei(&nd); 449 if (error) 450 return (error); 451 vp = nd.ni_vp; 452 if (vp != NULL) { 453 VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd); 454 if (nd.ni_dvp == vp) 455 vrele(nd.ni_dvp); 456 else 457 vput(nd.ni_dvp); 458 vrele(vp); 459 return (EADDRINUSE); 460 } 461 VATTR_NULL(&vattr); 462 vattr.va_type = VSOCK; 463 vattr.va_mode = ACCESSPERMS; 464 VOP_LEASE(nd.ni_dvp, p, p->p_ucred, LEASE_WRITE); 465 if (error = VOP_CREATE(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &vattr)) 466 return (error); 467 vp = nd.ni_vp; 468 vp->v_socket = unp->unp_socket; 469 unp->unp_vnode = vp; 470 unp->unp_addr = m_copy(nam, 0, (int)M_COPYALL); 471 VOP_UNLOCK(vp, 0, p); 472 return (0); 473} 474 475static int 476unp_connect(so, nam, p) 477 struct socket *so; 478 struct mbuf *nam; 479 struct proc *p; 480{ 481 register struct sockaddr_un *soun = mtod(nam, struct sockaddr_un *); 482 register struct vnode *vp; 483 register struct socket *so2, *so3; 484 struct unpcb *unp2, *unp3; 485 int error; 486 struct nameidata nd; 487 488 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, soun->sun_path, p); 489 if (nam->m_data + nam->m_len == &nam->m_dat[MLEN]) { /* XXX */ 490 if (*(mtod(nam, caddr_t) + nam->m_len - 1) != 0) 491 return (EMSGSIZE); 492 } else 493 *(mtod(nam, caddr_t) + nam->m_len) = 0; 494 error = namei(&nd); 495 if (error) 496 return (error); 497 vp = nd.ni_vp; 498 if (vp->v_type != VSOCK) { 499 error = ENOTSOCK; 500 goto bad; 501 } 502 error = VOP_ACCESS(vp, VWRITE, p->p_ucred, p); 503 if (error) 504 goto bad; 505 so2 = vp->v_socket; 506 if (so2 == 0) { 507 error = ECONNREFUSED; 508 goto bad; 509 } 510 if (so->so_type != so2->so_type) { 511 error = EPROTOTYPE; 512 goto bad; 513 } 514 if (so->so_proto->pr_flags & PR_CONNREQUIRED) { 515 if ((so2->so_options & SO_ACCEPTCONN) == 0 || 516 (so3 = sonewconn(so2, 0)) == 0) { 517 error = ECONNREFUSED; 518 goto bad; 519 } 520 unp2 = sotounpcb(so2); 521 unp3 = sotounpcb(so3); 522 if (unp2->unp_addr) 523 unp3->unp_addr = 524 m_copy(unp2->unp_addr, 0, (int)M_COPYALL); 525 so2 = so3; 526 } 527 error = unp_connect2(so, so2); 528bad: 529 vput(vp); 530 return (error); 531} 532 533int 534unp_connect2(so, so2) 535 register struct socket *so; 536 register struct socket *so2; 537{ 538 register struct unpcb *unp = sotounpcb(so); 539 register struct unpcb *unp2; 540 541 if (so2->so_type != so->so_type) 542 return (EPROTOTYPE); 543 unp2 = sotounpcb(so2); 544 unp->unp_conn = unp2; 545 switch (so->so_type) { 546 547 case SOCK_DGRAM: 548 unp->unp_nextref = unp2->unp_refs; 549 unp2->unp_refs = unp; 550 soisconnected(so); 551 break; 552 553 case SOCK_STREAM: 554 unp2->unp_conn = unp; 555 soisconnected(so); 556 soisconnected(so2); 557 break; 558 559 default: 560 panic("unp_connect2"); 561 } 562 return (0); 563} 564 565static void 566unp_disconnect(unp) 567 struct unpcb *unp; 568{ 569 register struct unpcb *unp2 = unp->unp_conn; 570 571 if (unp2 == 0) 572 return; 573 unp->unp_conn = 0; 574 switch (unp->unp_socket->so_type) { 575 576 case SOCK_DGRAM: 577 if (unp2->unp_refs == unp) 578 unp2->unp_refs = unp->unp_nextref; 579 else { 580 unp2 = unp2->unp_refs; 581 for (;;) { 582 if (unp2 == 0) 583 panic("unp_disconnect"); 584 if (unp2->unp_nextref == unp) 585 break; 586 unp2 = unp2->unp_nextref; 587 } 588 unp2->unp_nextref = unp->unp_nextref; 589 } 590 unp->unp_nextref = 0; 591 unp->unp_socket->so_state &= ~SS_ISCONNECTED; 592 break; 593 594 case SOCK_STREAM: 595 soisdisconnected(unp->unp_socket); 596 unp2->unp_conn = 0; 597 soisdisconnected(unp2->unp_socket); 598 break; 599 } 600} 601 602#ifdef notdef 603void 604unp_abort(unp) 605 struct unpcb *unp; 606{ 607 608 unp_detach(unp); 609} 610#endif 611 612static void 613unp_shutdown(unp) 614 struct unpcb *unp; 615{ 616 struct socket *so; 617 618 if (unp->unp_socket->so_type == SOCK_STREAM && unp->unp_conn && 619 (so = unp->unp_conn->unp_socket)) 620 socantrcvmore(so); 621} 622 623static void 624unp_drop(unp, errno) 625 struct unpcb *unp; 626 int errno; 627{ 628 struct socket *so = unp->unp_socket; 629 630 so->so_error = errno; 631 unp_disconnect(unp); 632 if (so->so_head) { 633 so->so_pcb = (caddr_t) 0; 634 m_freem(unp->unp_addr); 635 (void) m_free(dtom(unp)); 636 sofree(so); 637 } 638} 639 640#ifdef notdef 641void 642unp_drain() 643{ 644 645} 646#endif 647 648int 649unp_externalize(rights) 650 struct mbuf *rights; 651{ 652 struct proc *p = curproc; /* XXX */ 653 register int i; 654 register struct cmsghdr *cm = mtod(rights, struct cmsghdr *); 655 register struct file **rp = (struct file **)(cm + 1); 656 register struct file *fp; 657 int newfds = (cm->cmsg_len - sizeof(*cm)) / sizeof (int); 658 int f; 659 660 /* 661 * if the new FD's will not fit, then we free them all 662 */ 663 if (!fdavail(p, newfds)) { 664 for (i = 0; i < newfds; i++) { 665 fp = *rp; 666 unp_discard(fp); 667 *rp++ = 0; 668 } 669 return (EMSGSIZE); 670 } 671 /* 672 * now change each pointer to an fd in the global table to 673 * an integer that is the index to the local fd table entry 674 * that we set up to point to the global one we are transferring. 675 * XXX this assumes a pointer and int are the same size...! 676 */ 677 for (i = 0; i < newfds; i++) { 678 if (fdalloc(p, 0, &f)) 679 panic("unp_externalize"); 680 fp = *rp; 681 p->p_fd->fd_ofiles[f] = fp; 682 fp->f_msgcount--; 683 unp_rights--; 684 *(int *)rp++ = f; 685 } 686 return (0); 687} 688 689static int 690unp_internalize(control, p) 691 struct mbuf *control; 692 struct proc *p; 693{ 694 struct filedesc *fdp = p->p_fd; 695 register struct cmsghdr *cm = mtod(control, struct cmsghdr *); 696 register struct file **rp; 697 register struct file *fp; 698 register int i, fd; 699 int oldfds; 700 701 if (cm->cmsg_type != SCM_RIGHTS || cm->cmsg_level != SOL_SOCKET || 702 cm->cmsg_len != control->m_len) 703 return (EINVAL); 704 oldfds = (cm->cmsg_len - sizeof (*cm)) / sizeof (int); 705 /* 706 * check that all the FDs passed in refer to legal OPEN files 707 * If not, reject the entire operation. 708 */ 709 rp = (struct file **)(cm + 1); 710 for (i = 0; i < oldfds; i++) { 711 fd = *(int *)rp++; 712 if ((unsigned)fd >= fdp->fd_nfiles || 713 fdp->fd_ofiles[fd] == NULL) 714 return (EBADF); 715 } 716 /* 717 * Now replace the integer FDs with pointers to 718 * the associated global file table entry.. 719 * XXX this assumes a pointer and an int are the same size! 720 */ 721 rp = (struct file **)(cm + 1); 722 for (i = 0; i < oldfds; i++) { 723 fp = fdp->fd_ofiles[*(int *)rp]; 724 *rp++ = fp; 725 fp->f_count++; 726 fp->f_msgcount++; 727 unp_rights++; 728 } 729 return (0); 730} 731 732static int unp_defer, unp_gcing; 733 734static void 735unp_gc() 736{ 737 register struct file *fp, *nextfp; 738 register struct socket *so; 739 struct file **extra_ref, **fpp; 740 int nunref, i; 741 742 if (unp_gcing) 743 return; 744 unp_gcing = 1; 745 unp_defer = 0; 746 /* 747 * before going through all this, set all FDs to 748 * be NOT defered and NOT externally accessible 749 */ 750 for (fp = filehead.lh_first; fp != 0; fp = fp->f_list.le_next) 751 fp->f_flag &= ~(FMARK|FDEFER); 752 do { 753 for (fp = filehead.lh_first; fp != 0; fp = fp->f_list.le_next) { 754 /* 755 * If the file is not open, skip it 756 */ 757 if (fp->f_count == 0) 758 continue; 759 /* 760 * If we already marked it as 'defer' in a 761 * previous pass, then try process it this time 762 * and un-mark it 763 */ 764 if (fp->f_flag & FDEFER) { 765 fp->f_flag &= ~FDEFER; 766 unp_defer--; 767 } else { 768 /* 769 * if it's not defered, then check if it's 770 * already marked.. if so skip it 771 */ 772 if (fp->f_flag & FMARK) 773 continue; 774 /* 775 * If all references are from messages 776 * in transit, then skip it. it's not 777 * externally accessible. 778 */ 779 if (fp->f_count == fp->f_msgcount) 780 continue; 781 /* 782 * If it got this far then it must be 783 * externally accessible. 784 */ 785 fp->f_flag |= FMARK; 786 } 787 /* 788 * either it was defered, or it is externally 789 * accessible and not already marked so. 790 * Now check if it is possibly one of OUR sockets. 791 */ 792 if (fp->f_type != DTYPE_SOCKET || 793 (so = (struct socket *)fp->f_data) == 0) 794 continue; 795 if (so->so_proto->pr_domain != &localdomain || 796 (so->so_proto->pr_flags&PR_RIGHTS) == 0) 797 continue; 798#ifdef notdef 799 if (so->so_rcv.sb_flags & SB_LOCK) { 800 /* 801 * This is problematical; it's not clear 802 * we need to wait for the sockbuf to be 803 * unlocked (on a uniprocessor, at least), 804 * and it's also not clear what to do 805 * if sbwait returns an error due to receipt 806 * of a signal. If sbwait does return 807 * an error, we'll go into an infinite 808 * loop. Delete all of this for now. 809 */ 810 (void) sbwait(&so->so_rcv); 811 goto restart; 812 } 813#endif 814 /* 815 * So, Ok, it's one of our sockets and it IS externally 816 * accessible (or was defered). Now we look 817 * to see if we hold any file descriptors in it's 818 * message buffers. Follow those links and mark them 819 * as accessible too. 820 */ 821 unp_scan(so->so_rcv.sb_mb, unp_mark); 822 } 823 } while (unp_defer); 824 /* 825 * We grab an extra reference to each of the file table entries 826 * that are not otherwise accessible and then free the rights 827 * that are stored in messages on them. 828 * 829 * The bug in the orginal code is a little tricky, so I'll describe 830 * what's wrong with it here. 831 * 832 * It is incorrect to simply unp_discard each entry for f_msgcount 833 * times -- consider the case of sockets A and B that contain 834 * references to each other. On a last close of some other socket, 835 * we trigger a gc since the number of outstanding rights (unp_rights) 836 * is non-zero. If during the sweep phase the gc code un_discards, 837 * we end up doing a (full) closef on the descriptor. A closef on A 838 * results in the following chain. Closef calls soo_close, which 839 * calls soclose. Soclose calls first (through the switch 840 * uipc_usrreq) unp_detach, which re-invokes unp_gc. Unp_gc simply 841 * returns because the previous instance had set unp_gcing, and 842 * we return all the way back to soclose, which marks the socket 843 * with SS_NOFDREF, and then calls sofree. Sofree calls sorflush 844 * to free up the rights that are queued in messages on the socket A, 845 * i.e., the reference on B. The sorflush calls via the dom_dispose 846 * switch unp_dispose, which unp_scans with unp_discard. This second 847 * instance of unp_discard just calls closef on B. 848 * 849 * Well, a similar chain occurs on B, resulting in a sorflush on B, 850 * which results in another closef on A. Unfortunately, A is already 851 * being closed, and the descriptor has already been marked with 852 * SS_NOFDREF, and soclose panics at this point. 853 * 854 * Here, we first take an extra reference to each inaccessible 855 * descriptor. Then, we call sorflush ourself, since we know 856 * it is a Unix domain socket anyhow. After we destroy all the 857 * rights carried in messages, we do a last closef to get rid 858 * of our extra reference. This is the last close, and the 859 * unp_detach etc will shut down the socket. 860 * 861 * 91/09/19, bsy@cs.cmu.edu 862 */ 863 extra_ref = malloc(nfiles * sizeof(struct file *), M_FILE, M_WAITOK); 864 for (nunref = 0, fp = filehead.lh_first, fpp = extra_ref; fp != 0; 865 fp = nextfp) { 866 nextfp = fp->f_list.le_next; 867 /* 868 * If it's not open, skip it 869 */ 870 if (fp->f_count == 0) 871 continue; 872 /* 873 * If all refs are from msgs, and it's not marked accessible 874 * then it must be referenced from some unreachable cycle 875 * of (shut-down) FDs, so include it in our 876 * list of FDs to remove 877 */ 878 if (fp->f_count == fp->f_msgcount && !(fp->f_flag & FMARK)) { 879 *fpp++ = fp; 880 nunref++; 881 fp->f_count++; 882 } 883 } 884 /* 885 * for each FD on our hit list, do the following two things 886 */ 887 for (i = nunref, fpp = extra_ref; --i >= 0; ++fpp) 888 sorflush((struct socket *)(*fpp)->f_data); 889 for (i = nunref, fpp = extra_ref; --i >= 0; ++fpp) 890 closef(*fpp, (struct proc *) NULL); 891 free((caddr_t)extra_ref, M_FILE); 892 unp_gcing = 0; 893} 894 895void 896unp_dispose(m) 897 struct mbuf *m; 898{ 899 900 if (m) 901 unp_scan(m, unp_discard); 902} 903 904static void 905unp_scan(m0, op) 906 register struct mbuf *m0; 907 void (*op) __P((struct file *)); 908{ 909 register struct mbuf *m; 910 register struct file **rp; 911 register struct cmsghdr *cm; 912 register int i; 913 int qfds; 914 915 while (m0) { 916 for (m = m0; m; m = m->m_next) 917 if (m->m_type == MT_CONTROL && 918 m->m_len >= sizeof(*cm)) { 919 cm = mtod(m, struct cmsghdr *); 920 if (cm->cmsg_level != SOL_SOCKET || 921 cm->cmsg_type != SCM_RIGHTS) 922 continue; 923 qfds = (cm->cmsg_len - sizeof *cm) 924 / sizeof (struct file *); 925 rp = (struct file **)(cm + 1); 926 for (i = 0; i < qfds; i++) 927 (*op)(*rp++); 928 break; /* XXX, but saves time */ 929 } 930 m0 = m0->m_act; 931 } 932} 933 934static void 935unp_mark(fp) 936 struct file *fp; 937{ 938 939 if (fp->f_flag & FMARK) 940 return; 941 unp_defer++; 942 fp->f_flag |= (FMARK|FDEFER); 943} 944 945static void 946unp_discard(fp) 947 struct file *fp; 948{ 949 950 fp->f_msgcount--; 951 unp_rights--; 952 (void) closef(fp, (struct proc *)NULL); 953} 954