Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/kern/uipc_usrreq.c
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1 /* 2 * Copyright (c) 1982, 1986, 1989, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 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 * $FreeBSD: src/sys/kern/uipc_usrreq.c,v 1.15.4.3 1999/09/05 08:15:37 peter Exp $ 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 */ 63 static struct sockaddr sun_noname = { sizeof(sun_noname), AF_LOCAL }; 64 static ino_t unp_ino; /* prototype for fake inode numbers */ 65 66 static int unp_attach __P((struct socket *)); 67 static void unp_detach __P((struct unpcb *)); 68 static int unp_bind __P((struct unpcb *,struct mbuf *, struct proc *)); 69 static int unp_connect __P((struct socket *,struct mbuf *, struct proc *)); 70 static void unp_disconnect __P((struct unpcb *)); 71 static void unp_shutdown __P((struct unpcb *)); 72 static void unp_drop __P((struct unpcb *, int)); 73 static void unp_gc __P((void)); 74 static void unp_scan __P((struct mbuf *, void (*)(struct file *))); 75 static void unp_mark __P((struct file *)); 76 static void unp_discard __P((struct file *)); 77 static int unp_internalize __P((struct mbuf *, struct proc *)); 78 79 80 /*ARGSUSED*/ 81 int 82 uipc_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 } 335 release: 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 354 static u_long unpst_sendspace = PIPSIZ; 355 static u_long unpst_recvspace = PIPSIZ; 356 static u_long unpdg_sendspace = 2*1024; /* really max datagram size */ 357 static u_long unpdg_recvspace = 4*1024; 358 359 static int unp_rights; /* file descriptors in flight */ 360 361 static int 362 unp_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 } 394 395 static void 396 unp_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 } 425 426 static int 427 unp_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 & ~p->p_fd->fd_cmask); 464 LEASE_CHECK(nd.ni_dvp, p, p->p_ucred, LEASE_WRITE); 465 error = VOP_CREATE(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &vattr); 466 if (error) 467 return (error); 468 vp = nd.ni_vp; 469 vp->v_socket = unp->unp_socket; 470 unp->unp_vnode = vp; 471 unp->unp_addr = m_copy(nam, 0, (int)M_COPYALL); 472 VOP_UNLOCK(vp); 473 return (0); 474 } 475 476 static int 477 unp_connect(so, nam, p) 478 struct socket *so; 479 struct mbuf *nam; 480 struct proc *p; 481 { 482 register struct sockaddr_un *soun = mtod(nam, struct sockaddr_un *); 483 register struct vnode *vp; 484 register struct socket *so2, *so3; 485 struct unpcb *unp2, *unp3; 486 int error; 487 struct nameidata nd; 488 489 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, soun->sun_path, p); 490 if (nam->m_data + nam->m_len == &nam->m_dat[MLEN]) { /* XXX */ 491 if (*(mtod(nam, caddr_t) + nam->m_len - 1) != 0) 492 return (EMSGSIZE); 493 } else 494 *(mtod(nam, caddr_t) + nam->m_len) = 0; 495 error = namei(&nd); 496 if (error) 497 return (error); 498 vp = nd.ni_vp; 499 if (vp->v_type != VSOCK) { 500 error = ENOTSOCK; 501 goto bad; 502 } 503 error = VOP_ACCESS(vp, VWRITE, p->p_ucred, p); 504 if (error) 505 goto bad; 506 so2 = vp->v_socket; 507 if (so2 == 0) { 508 error = ECONNREFUSED; 509 goto bad; 510 } 511 if (so->so_type != so2->so_type) { 512 error = EPROTOTYPE; 513 goto bad; 514 } 515 if (so->so_proto->pr_flags & PR_CONNREQUIRED) { 516 if ((so2->so_options & SO_ACCEPTCONN) == 0 || 517 (so3 = sonewconn(so2, 0)) == 0) { 518 error = ECONNREFUSED; 519 goto bad; 520 } 521 unp2 = sotounpcb(so2); 522 unp3 = sotounpcb(so3); 523 if (unp2->unp_addr) 524 unp3->unp_addr = 525 m_copy(unp2->unp_addr, 0, (int)M_COPYALL); 526 so2 = so3; 527 } 528 error = unp_connect2(so, so2); 529 bad: 530 vput(vp); 531 return (error); 532 } 533 534 int 535 unp_connect2(so, so2) 536 register struct socket *so; 537 register struct socket *so2; 538 { 539 register struct unpcb *unp = sotounpcb(so); 540 register struct unpcb *unp2; 541 542 if (so2->so_type != so->so_type) 543 return (EPROTOTYPE); 544 unp2 = sotounpcb(so2); 545 unp->unp_conn = unp2; 546 switch (so->so_type) { 547 548 case SOCK_DGRAM: 549 unp->unp_nextref = unp2->unp_refs; 550 unp2->unp_refs = unp; 551 soisconnected(so); 552 break; 553 554 case SOCK_STREAM: 555 unp2->unp_conn = unp; 556 soisconnected(so); 557 soisconnected(so2); 558 break; 559 560 default: 561 panic("unp_connect2"); 562 } 563 return (0); 564 } 565 566 static void 567 unp_disconnect(unp) 568 struct unpcb *unp; 569 { 570 register struct unpcb *unp2 = unp->unp_conn; 571 572 if (unp2 == 0) 573 return; 574 unp->unp_conn = 0; 575 switch (unp->unp_socket->so_type) { 576 577 case SOCK_DGRAM: 578 if (unp2->unp_refs == unp) 579 unp2->unp_refs = unp->unp_nextref; 580 else { 581 unp2 = unp2->unp_refs; 582 for (;;) { 583 if (unp2 == 0) 584 panic("unp_disconnect"); 585 if (unp2->unp_nextref == unp) 586 break; 587 unp2 = unp2->unp_nextref; 588 } 589 unp2->unp_nextref = unp->unp_nextref; 590 } 591 unp->unp_nextref = 0; 592 unp->unp_socket->so_state &= ~SS_ISCONNECTED; 593 break; 594 595 case SOCK_STREAM: 596 soisdisconnected(unp->unp_socket); 597 unp2->unp_conn = 0; 598 soisdisconnected(unp2->unp_socket); 599 break; 600 } 601 } 602 603 #ifdef notdef 604 void 605 unp_abort(unp) 606 struct unpcb *unp; 607 { 608 609 unp_detach(unp); 610 } 611 #endif 612 613 static void 614 unp_shutdown(unp) 615 struct unpcb *unp; 616 { 617 struct socket *so; 618 619 if (unp->unp_socket->so_type == SOCK_STREAM && unp->unp_conn && 620 (so = unp->unp_conn->unp_socket)) 621 socantrcvmore(so); 622 } 623 624 static void 625 unp_drop(unp, errno) 626 struct unpcb *unp; 627 int errno; 628 { 629 struct socket *so = unp->unp_socket; 630 631 so->so_error = errno; 632 unp_disconnect(unp); 633 if (so->so_head) { 634 so->so_pcb = (caddr_t) 0; 635 m_freem(unp->unp_addr); 636 (void) m_free(dtom(unp)); 637 sofree(so); 638 } 639 } 640 641 #ifdef notdef 642 void 643 unp_drain() 644 { 645 646 } 647 #endif 648 649 int 650 unp_externalize(rights) 651 struct mbuf *rights; 652 { 653 struct proc *p = curproc; /* XXX */ 654 register int i; 655 register struct cmsghdr *cm = mtod(rights, struct cmsghdr *); 656 register struct file **rp = (struct file **)(cm + 1); 657 register struct file *fp; 658 int newfds = (cm->cmsg_len - sizeof(*cm)) / sizeof (int); 659 int f; 660 661 /* 662 * if the new FD's will not fit, then we free them all 663 */ 664 if (!fdavail(p, newfds)) { 665 for (i = 0; i < newfds; i++) { 666 fp = *rp; 667 unp_discard(fp); 668 *rp++ = 0; 669 } 670 return (EMSGSIZE); 671 } 672 /* 673 * now change each pointer to an fd in the global table to 674 * an integer that is the index to the local fd table entry 675 * that we set up to point to the global one we are transferring. 676 * XXX this assumes a pointer and int are the same size...! 677 */ 678 for (i = 0; i < newfds; i++) { 679 if (fdalloc(p, 0, &f)) 680 panic("unp_externalize"); 681 fp = *rp; 682 p->p_fd->fd_ofiles[f] = fp; 683 fp->f_msgcount--; 684 unp_rights--; 685 *(int *)rp++ = f; 686 } 687 return (0); 688 } 689 690 static int 691 unp_internalize(control, p) 692 struct mbuf *control; 693 struct proc *p; 694 { 695 struct filedesc *fdp = p->p_fd; 696 register struct cmsghdr *cm = mtod(control, struct cmsghdr *); 697 register struct file **rp; 698 register struct file *fp; 699 register int i, fd; 700 int oldfds; 701 702 if (cm->cmsg_type != SCM_RIGHTS || cm->cmsg_level != SOL_SOCKET || 703 cm->cmsg_len != control->m_len) 704 return (EINVAL); 705 oldfds = (cm->cmsg_len - sizeof (*cm)) / sizeof (int); 706 /* 707 * check that all the FDs passed in refer to legal OPEN files 708 * If not, reject the entire operation. 709 */ 710 rp = (struct file **)(cm + 1); 711 for (i = 0; i < oldfds; i++) { 712 fd = *(int *)rp++; 713 if ((unsigned)fd >= fdp->fd_nfiles || 714 fdp->fd_ofiles[fd] == NULL) 715 return (EBADF); 716 } 717 /* 718 * Now replace the integer FDs with pointers to 719 * the associated global file table entry.. 720 * XXX this assumes a pointer and an int are the same size! 721 */ 722 rp = (struct file **)(cm + 1); 723 for (i = 0; i < oldfds; i++) { 724 fp = fdp->fd_ofiles[*(int *)rp]; 725 *rp++ = fp; 726 fp->f_count++; 727 fp->f_msgcount++; 728 unp_rights++; 729 } 730 return (0); 731 } 732 733 static int unp_defer, unp_gcing; 734 735 static void 736 unp_gc() 737 { 738 register struct file *fp, *nextfp; 739 register struct socket *so; 740 struct file **extra_ref, **fpp; 741 int nunref, i; 742 743 if (unp_gcing) 744 return; 745 unp_gcing = 1; 746 unp_defer = 0; 747 /* 748 * before going through all this, set all FDs to 749 * be NOT defered and NOT externally accessible 750 */ 751 for (fp = filehead.lh_first; fp != 0; fp = fp->f_list.le_next) 752 fp->f_flag &= ~(FMARK|FDEFER); 753 do { 754 for (fp = filehead.lh_first; fp != 0; fp = fp->f_list.le_next) { 755 /* 756 * If the file is not open, skip it 757 */ 758 if (fp->f_count == 0) 759 continue; 760 /* 761 * If we already marked it as 'defer' in a 762 * previous pass, then try process it this time 763 * and un-mark it 764 */ 765 if (fp->f_flag & FDEFER) { 766 fp->f_flag &= ~FDEFER; 767 unp_defer--; 768 } else { 769 /* 770 * if it's not defered, then check if it's 771 * already marked.. if so skip it 772 */ 773 if (fp->f_flag & FMARK) 774 continue; 775 /* 776 * If all references are from messages 777 * in transit, then skip it. it's not 778 * externally accessible. 779 */ 780 if (fp->f_count == fp->f_msgcount) 781 continue; 782 /* 783 * If it got this far then it must be 784 * externally accessible. 785 */ 786 fp->f_flag |= FMARK; 787 } 788 /* 789 * either it was defered, or it is externally 790 * accessible and not already marked so. 791 * Now check if it is possibly one of OUR sockets. 792 */ 793 if (fp->f_type != DTYPE_SOCKET || 794 (so = (struct socket *)fp->f_data) == 0) 795 continue; 796 if (so->so_proto->pr_domain != &localdomain || 797 (so->so_proto->pr_flags&PR_RIGHTS) == 0) 798 continue; 799 #ifdef notdef 800 if (so->so_rcv.sb_flags & SB_LOCK) { 801 /* 802 * This is problematical; it's not clear 803 * we need to wait for the sockbuf to be 804 * unlocked (on a uniprocessor, at least), 805 * and it's also not clear what to do 806 * if sbwait returns an error due to receipt 807 * of a signal. If sbwait does return 808 * an error, we'll go into an infinite 809 * loop. Delete all of this for now. 810 */ 811 (void) sbwait(&so->so_rcv); 812 goto restart; 813 } 814 #endif 815 /* 816 * So, Ok, it's one of our sockets and it IS externally 817 * accessible (or was defered). Now we look 818 * to see if we hold any file descriptors in it's 819 * message buffers. Follow those links and mark them 820 * as accessible too. 821 */ 822 unp_scan(so->so_rcv.sb_mb, unp_mark); 823 } 824 } while (unp_defer); 825 /* 826 * We grab an extra reference to each of the file table entries 827 * that are not otherwise accessible and then free the rights 828 * that are stored in messages on them. 829 * 830 * The bug in the orginal code is a little tricky, so I'll describe 831 * what's wrong with it here. 832 * 833 * It is incorrect to simply unp_discard each entry for f_msgcount 834 * times -- consider the case of sockets A and B that contain 835 * references to each other. On a last close of some other socket, 836 * we trigger a gc since the number of outstanding rights (unp_rights) 837 * is non-zero. If during the sweep phase the gc code un_discards, 838 * we end up doing a (full) closef on the descriptor. A closef on A 839 * results in the following chain. Closef calls soo_close, which 840 * calls soclose. Soclose calls first (through the switch 841 * uipc_usrreq) unp_detach, which re-invokes unp_gc. Unp_gc simply 842 * returns because the previous instance had set unp_gcing, and 843 * we return all the way back to soclose, which marks the socket 844 * with SS_NOFDREF, and then calls sofree. Sofree calls sorflush 845 * to free up the rights that are queued in messages on the socket A, 846 * i.e., the reference on B. The sorflush calls via the dom_dispose 847 * switch unp_dispose, which unp_scans with unp_discard. This second 848 * instance of unp_discard just calls closef on B. 849 * 850 * Well, a similar chain occurs on B, resulting in a sorflush on B, 851 * which results in another closef on A. Unfortunately, A is already 852 * being closed, and the descriptor has already been marked with 853 * SS_NOFDREF, and soclose panics at this point. 854 * 855 * Here, we first take an extra reference to each inaccessible 856 * descriptor. Then, we call sorflush ourself, since we know 857 * it is a Unix domain socket anyhow. After we destroy all the 858 * rights carried in messages, we do a last closef to get rid 859 * of our extra reference. This is the last close, and the 860 * unp_detach etc will shut down the socket. 861 * 862 * 91/09/19, bsy@cs.cmu.edu 863 */ 864 extra_ref = malloc(nfiles * sizeof(struct file *), M_FILE, M_WAITOK); 865 for (nunref = 0, fp = filehead.lh_first, fpp = extra_ref; fp != 0; 866 fp = nextfp) { 867 nextfp = fp->f_list.le_next; 868 /* 869 * If it's not open, skip it 870 */ 871 if (fp->f_count == 0) 872 continue; 873 /* 874 * If all refs are from msgs, and it's not marked accessible 875 * then it must be referenced from some unreachable cycle 876 * of (shut-down) FDs, so include it in our 877 * list of FDs to remove 878 */ 879 if (fp->f_count == fp->f_msgcount && !(fp->f_flag & FMARK)) { 880 *fpp++ = fp; 881 nunref++; 882 fp->f_count++; 883 } 884 } 885 /* 886 * for each FD on our hit list, do the following two things 887 */ 888 for (i = nunref, fpp = extra_ref; --i >= 0; ++fpp) 889 sorflush((struct socket *)(*fpp)->f_data); 890 for (i = nunref, fpp = extra_ref; --i >= 0; ++fpp) 891 closef(*fpp,(struct proc*) NULL); 892 free((caddr_t)extra_ref, M_FILE); 893 unp_gcing = 0; 894 } 895 896 void 897 unp_dispose(m) 898 struct mbuf *m; 899 { 900 if (m) 901 unp_scan(m, unp_discard); 902 } 903 904 static void 905 unp_scan(m0, op) 906 register struct mbuf *m0; 907 void (*op)(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 } 933 934 static void 935 unp_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 } 944 945 static void 946 unp_discard(fp) 947 struct file *fp; 948 { 949 950 fp->f_msgcount--; 951 unp_rights--; 952 (void) closef(fp, (struct proc *)NULL); 953 }
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