uipc_usrreq.c revision 1.8
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: uipc_usrreq.c,v 1.8 1994/05/04 09:50:11 mycroft 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/socket.h> 44 #include <sys/socketvar.h> 45 #include <sys/unpcb.h> 46 #include <sys/un.h> 47 #include <sys/namei.h> 48 #include <sys/vnode.h> 49 #include <sys/file.h> 50 #include <sys/stat.h> 51 #include <sys/mbuf.h> 52 53 /* 54 * Unix communications domain. 55 * 56 * TODO: 57 * SEQPACKET, RDM 58 * rethink name space problems 59 * need a proper out-of-band 60 */ 61 struct sockaddr sun_noname = { sizeof(sun_noname), AF_UNIX }; 62 ino_t unp_ino; /* prototype for fake inode numbers */ 63 64 /*ARGSUSED*/ 65 int 66 uipc_usrreq(so, req, m, nam, control) 67 struct socket *so; 68 int req; 69 struct mbuf *m, *nam, *control; 70 { 71 struct unpcb *unp = sotounpcb(so); 72 register struct socket *so2; 73 register int error = 0; 74 struct proc *p = curproc; /* XXX */ 75 76 if (req == PRU_CONTROL) 77 return (EOPNOTSUPP); 78 if (req != PRU_SEND && control && control->m_len) { 79 error = EOPNOTSUPP; 80 goto release; 81 } 82 if (unp == 0 && req != PRU_ATTACH) { 83 error = EINVAL; 84 goto release; 85 } 86 switch (req) { 87 88 case PRU_ATTACH: 89 if (unp) { 90 error = EISCONN; 91 break; 92 } 93 error = unp_attach(so); 94 break; 95 96 case PRU_DETACH: 97 unp_detach(unp); 98 break; 99 100 case PRU_BIND: 101 error = unp_bind(unp, nam, p); 102 break; 103 104 case PRU_LISTEN: 105 if (unp->unp_vnode == 0) 106 error = EINVAL; 107 break; 108 109 case PRU_CONNECT: 110 error = unp_connect(so, nam, p); 111 break; 112 113 case PRU_CONNECT2: 114 error = unp_connect2(so, (struct socket *)nam); 115 break; 116 117 case PRU_DISCONNECT: 118 unp_disconnect(unp); 119 break; 120 121 case PRU_ACCEPT: 122 /* 123 * Pass back name of connected socket, 124 * if it was bound and we are still connected 125 * (our peer may have closed already!). 126 */ 127 if (unp->unp_conn && unp->unp_conn->unp_addr) { 128 nam->m_len = unp->unp_conn->unp_addr->m_len; 129 bcopy(mtod(unp->unp_conn->unp_addr, caddr_t), 130 mtod(nam, caddr_t), (unsigned)nam->m_len); 131 } else { 132 nam->m_len = sizeof(sun_noname); 133 *(mtod(nam, struct sockaddr *)) = sun_noname; 134 } 135 break; 136 137 case PRU_SHUTDOWN: 138 socantsendmore(so); 139 unp_shutdown(unp); 140 break; 141 142 case PRU_RCVD: 143 switch (so->so_type) { 144 145 case SOCK_DGRAM: 146 panic("uipc 1"); 147 /*NOTREACHED*/ 148 149 case SOCK_STREAM: 150 #define rcv (&so->so_rcv) 151 #define snd (&so2->so_snd) 152 if (unp->unp_conn == 0) 153 break; 154 so2 = unp->unp_conn->unp_socket; 155 /* 156 * Adjust backpressure on sender 157 * and wakeup any waiting to write. 158 */ 159 snd->sb_mbmax += unp->unp_mbcnt - rcv->sb_mbcnt; 160 unp->unp_mbcnt = rcv->sb_mbcnt; 161 snd->sb_hiwat += unp->unp_cc - rcv->sb_cc; 162 unp->unp_cc = rcv->sb_cc; 163 sowwakeup(so2); 164 #undef snd 165 #undef rcv 166 break; 167 168 default: 169 panic("uipc 2"); 170 } 171 break; 172 173 case PRU_SEND: 174 if (control && (error = unp_internalize(control, p))) 175 break; 176 switch (so->so_type) { 177 178 case SOCK_DGRAM: { 179 struct sockaddr *from; 180 181 if (nam) { 182 if (unp->unp_conn) { 183 error = EISCONN; 184 break; 185 } 186 error = unp_connect(so, nam, p); 187 if (error) 188 break; 189 } else { 190 if (unp->unp_conn == 0) { 191 error = ENOTCONN; 192 break; 193 } 194 } 195 so2 = unp->unp_conn->unp_socket; 196 if (unp->unp_addr) 197 from = mtod(unp->unp_addr, struct sockaddr *); 198 else 199 from = &sun_noname; 200 if (sbappendaddr(&so2->so_rcv, from, m, control)) { 201 sorwakeup(so2); 202 m = 0; 203 control = 0; 204 } else 205 error = ENOBUFS; 206 if (nam) 207 unp_disconnect(unp); 208 break; 209 } 210 211 case SOCK_STREAM: 212 #define rcv (&so2->so_rcv) 213 #define snd (&so->so_snd) 214 if (so->so_state & SS_CANTSENDMORE) { 215 error = EPIPE; 216 break; 217 } 218 if (unp->unp_conn == 0) 219 panic("uipc 3"); 220 so2 = unp->unp_conn->unp_socket; 221 /* 222 * Send to paired receive port, and then reduce 223 * send buffer hiwater marks to maintain backpressure. 224 * Wake up readers. 225 */ 226 if (control) { 227 if (sbappendcontrol(rcv, m, control)) 228 control = 0; 229 } else 230 sbappend(rcv, m); 231 snd->sb_mbmax -= 232 rcv->sb_mbcnt - unp->unp_conn->unp_mbcnt; 233 unp->unp_conn->unp_mbcnt = rcv->sb_mbcnt; 234 snd->sb_hiwat -= rcv->sb_cc - unp->unp_conn->unp_cc; 235 unp->unp_conn->unp_cc = rcv->sb_cc; 236 sorwakeup(so2); 237 m = 0; 238 #undef snd 239 #undef rcv 240 break; 241 242 default: 243 panic("uipc 4"); 244 } 245 break; 246 247 case PRU_ABORT: 248 unp_drop(unp, ECONNABORTED); 249 break; 250 251 case PRU_SENSE: 252 ((struct stat *) m)->st_blksize = so->so_snd.sb_hiwat; 253 if (so->so_type == SOCK_STREAM && unp->unp_conn != 0) { 254 so2 = unp->unp_conn->unp_socket; 255 ((struct stat *) m)->st_blksize += so2->so_rcv.sb_cc; 256 } 257 ((struct stat *) m)->st_dev = NODEV; 258 if (unp->unp_ino == 0) 259 unp->unp_ino = unp_ino++; 260 ((struct stat *) m)->st_ino = unp->unp_ino; 261 return (0); 262 263 case PRU_RCVOOB: 264 return (EOPNOTSUPP); 265 266 case PRU_SENDOOB: 267 error = EOPNOTSUPP; 268 break; 269 270 case PRU_SOCKADDR: 271 if (unp->unp_addr) { 272 nam->m_len = unp->unp_addr->m_len; 273 bcopy(mtod(unp->unp_addr, caddr_t), 274 mtod(nam, caddr_t), (unsigned)nam->m_len); 275 } else 276 nam->m_len = 0; 277 break; 278 279 case PRU_PEERADDR: 280 if (unp->unp_conn && unp->unp_conn->unp_addr) { 281 nam->m_len = unp->unp_conn->unp_addr->m_len; 282 bcopy(mtod(unp->unp_conn->unp_addr, caddr_t), 283 mtod(nam, caddr_t), (unsigned)nam->m_len); 284 } else 285 nam->m_len = 0; 286 break; 287 288 case PRU_SLOWTIMO: 289 break; 290 291 default: 292 panic("piusrreq"); 293 } 294 release: 295 if (control) 296 m_freem(control); 297 if (m) 298 m_freem(m); 299 return (error); 300 } 301 302 /* 303 * Both send and receive buffers are allocated PIPSIZ bytes of buffering 304 * for stream sockets, although the total for sender and receiver is 305 * actually only PIPSIZ. 306 * Datagram sockets really use the sendspace as the maximum datagram size, 307 * and don't really want to reserve the sendspace. Their recvspace should 308 * be large enough for at least one max-size datagram plus address. 309 */ 310 #define PIPSIZ 4096 311 u_long unpst_sendspace = PIPSIZ; 312 u_long unpst_recvspace = PIPSIZ; 313 u_long unpdg_sendspace = 2*1024; /* really max datagram size */ 314 u_long unpdg_recvspace = 4*1024; 315 316 int unp_rights; /* file descriptors in flight */ 317 318 int 319 unp_attach(so) 320 struct socket *so; 321 { 322 register struct mbuf *m; 323 register struct unpcb *unp; 324 int error; 325 326 if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) { 327 switch (so->so_type) { 328 329 case SOCK_STREAM: 330 error = soreserve(so, unpst_sendspace, unpst_recvspace); 331 break; 332 333 case SOCK_DGRAM: 334 error = soreserve(so, unpdg_sendspace, unpdg_recvspace); 335 break; 336 337 default: 338 panic("unp_attach"); 339 } 340 if (error) 341 return (error); 342 } 343 m = m_getclr(M_DONTWAIT, MT_PCB); 344 if (m == NULL) 345 return (ENOBUFS); 346 unp = mtod(m, struct unpcb *); 347 so->so_pcb = (caddr_t)unp; 348 unp->unp_socket = so; 349 return (0); 350 } 351 352 int 353 unp_detach(unp) 354 register struct unpcb *unp; 355 { 356 357 if (unp->unp_vnode) { 358 unp->unp_vnode->v_socket = 0; 359 vrele(unp->unp_vnode); 360 unp->unp_vnode = 0; 361 } 362 if (unp->unp_conn) 363 unp_disconnect(unp); 364 while (unp->unp_refs) 365 unp_drop(unp->unp_refs, ECONNRESET); 366 soisdisconnected(unp->unp_socket); 367 unp->unp_socket->so_pcb = 0; 368 m_freem(unp->unp_addr); 369 (void) m_free(dtom(unp)); 370 if (unp_rights) { 371 /* 372 * Normally the receive buffer is flushed later, 373 * in sofree, but if our receive buffer holds references 374 * to descriptors that are now garbage, we will dispose 375 * of those descriptor references after the garbage collector 376 * gets them (resulting in a "panic: closef: count < 0"). 377 */ 378 sorflush(unp->unp_socket); 379 unp_gc(); 380 } 381 } 382 383 int 384 unp_bind(unp, nam, p) 385 struct unpcb *unp; 386 struct mbuf *nam; 387 struct proc *p; 388 { 389 struct sockaddr_un *soun = mtod(nam, struct sockaddr_un *); 390 register struct vnode *vp; 391 register struct nameidata *ndp; 392 struct vattr vattr; 393 int error; 394 struct nameidata nd; 395 396 ndp = &nd; 397 ndp->ni_dirp = soun->sun_path; 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 ndp->ni_nameiop = CREATE | FOLLOW | LOCKPARENT; 407 ndp->ni_segflg = UIO_SYSSPACE; 408 if (error = namei(ndp, p)) 409 return (error); 410 vp = ndp->ni_vp; 411 if (vp != NULL) { 412 VOP_ABORTOP(ndp); 413 if (ndp->ni_dvp == vp) 414 vrele(ndp->ni_dvp); 415 else 416 vput(ndp->ni_dvp); 417 vrele(vp); 418 return (EADDRINUSE); 419 } 420 VATTR_NULL(&vattr); 421 vattr.va_type = VSOCK; 422 vattr.va_mode = 0777; 423 if (error = VOP_CREATE(ndp, &vattr, p)) 424 return (error); 425 vp = ndp->ni_vp; 426 vp->v_socket = unp->unp_socket; 427 unp->unp_vnode = vp; 428 unp->unp_addr = m_copy(nam, 0, (int)M_COPYALL); 429 VOP_UNLOCK(vp); 430 return (0); 431 } 432 433 int 434 unp_connect(so, nam, p) 435 struct socket *so; 436 struct mbuf *nam; 437 struct proc *p; 438 { 439 register struct sockaddr_un *soun = mtod(nam, struct sockaddr_un *); 440 register struct vnode *vp; 441 register struct socket *so2, *so3; 442 register struct nameidata *ndp; 443 struct unpcb *unp2, *unp3; 444 int error; 445 struct nameidata nd; 446 447 ndp = &nd; 448 ndp->ni_dirp = soun->sun_path; 449 if (nam->m_data + nam->m_len == &nam->m_dat[MLEN]) { /* XXX */ 450 if (*(mtod(nam, caddr_t) + nam->m_len - 1) != 0) 451 return (EMSGSIZE); 452 } else 453 *(mtod(nam, caddr_t) + nam->m_len) = 0; 454 ndp->ni_nameiop = LOOKUP | FOLLOW | LOCKLEAF; 455 ndp->ni_segflg = UIO_SYSSPACE; 456 if (error = namei(ndp, p)) 457 return (error); 458 vp = ndp->ni_vp; 459 if (vp->v_type != VSOCK) { 460 error = ENOTSOCK; 461 goto bad; 462 } 463 if (error = VOP_ACCESS(vp, VWRITE, p->p_ucred, p)) 464 goto bad; 465 so2 = vp->v_socket; 466 if (so2 == 0) { 467 error = ECONNREFUSED; 468 goto bad; 469 } 470 if (so->so_type != so2->so_type) { 471 error = EPROTOTYPE; 472 goto bad; 473 } 474 if (so->so_proto->pr_flags & PR_CONNREQUIRED) { 475 if ((so2->so_options & SO_ACCEPTCONN) == 0 || 476 (so3 = sonewconn(so2, 0)) == 0) { 477 error = ECONNREFUSED; 478 goto bad; 479 } 480 unp2 = sotounpcb(so2); 481 unp3 = sotounpcb(so3); 482 if (unp2->unp_addr) 483 unp3->unp_addr = 484 m_copy(unp2->unp_addr, 0, (int)M_COPYALL); 485 so2 = so3; 486 } 487 error = unp_connect2(so, so2); 488 bad: 489 vput(vp); 490 return (error); 491 } 492 493 int 494 unp_connect2(so, so2) 495 register struct socket *so; 496 register struct socket *so2; 497 { 498 register struct unpcb *unp = sotounpcb(so); 499 register struct unpcb *unp2; 500 501 if (so2->so_type != so->so_type) 502 return (EPROTOTYPE); 503 unp2 = sotounpcb(so2); 504 unp->unp_conn = unp2; 505 switch (so->so_type) { 506 507 case SOCK_DGRAM: 508 unp->unp_nextref = unp2->unp_refs; 509 unp2->unp_refs = unp; 510 soisconnected(so); 511 break; 512 513 case SOCK_STREAM: 514 unp2->unp_conn = unp; 515 soisconnected(so); 516 soisconnected(so2); 517 break; 518 519 default: 520 panic("unp_connect2"); 521 } 522 return (0); 523 } 524 525 void 526 unp_disconnect(unp) 527 struct unpcb *unp; 528 { 529 register struct unpcb *unp2 = unp->unp_conn; 530 531 if (unp2 == 0) 532 return; 533 unp->unp_conn = 0; 534 switch (unp->unp_socket->so_type) { 535 536 case SOCK_DGRAM: 537 if (unp2->unp_refs == unp) 538 unp2->unp_refs = unp->unp_nextref; 539 else { 540 unp2 = unp2->unp_refs; 541 for (;;) { 542 if (unp2 == 0) 543 panic("unp_disconnect"); 544 if (unp2->unp_nextref == unp) 545 break; 546 unp2 = unp2->unp_nextref; 547 } 548 unp2->unp_nextref = unp->unp_nextref; 549 } 550 unp->unp_nextref = 0; 551 unp->unp_socket->so_state &= ~SS_ISCONNECTED; 552 break; 553 554 case SOCK_STREAM: 555 soisdisconnected(unp->unp_socket); 556 unp2->unp_conn = 0; 557 soisdisconnected(unp2->unp_socket); 558 break; 559 } 560 } 561 562 #ifdef notdef 563 unp_abort(unp) 564 struct unpcb *unp; 565 { 566 567 unp_detach(unp); 568 } 569 #endif 570 571 void 572 unp_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 } 581 582 void 583 unp_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 600 unp_drain() 601 { 602 603 } 604 #endif 605 606 int 607 unp_externalize(rights) 608 struct mbuf *rights; 609 { 610 struct proc *p = curproc; /* XXX */ 611 register int i; 612 register struct cmsghdr *cm = mtod(rights, struct cmsghdr *); 613 register struct file **rp = (struct file **)(cm + 1); 614 register struct file *fp; 615 int newfds = (cm->cmsg_len - sizeof(*cm)) / sizeof (int); 616 int f; 617 618 if (!fdavail(p, newfds)) { 619 for (i = 0; i < newfds; i++) { 620 fp = *rp; 621 unp_discard(fp); 622 *rp++ = 0; 623 } 624 return (EMSGSIZE); 625 } 626 for (i = 0; i < newfds; i++) { 627 if (fdalloc(p, 0, &f)) 628 panic("unp_externalize"); 629 fp = *rp; 630 p->p_fd->fd_ofiles[f] = fp; 631 fp->f_msgcount--; 632 unp_rights--; 633 *(int *)rp++ = f; 634 } 635 return (0); 636 } 637 638 int 639 unp_internalize(control, p) 640 struct mbuf *control; 641 struct proc *p; 642 { 643 struct filedesc *fdp = p->p_fd; 644 register struct cmsghdr *cm = mtod(control, struct cmsghdr *); 645 register struct file **rp; 646 register struct file *fp; 647 register int i, fd; 648 int oldfds; 649 650 if (cm->cmsg_type != SCM_RIGHTS || cm->cmsg_level != SOL_SOCKET || 651 cm->cmsg_len != control->m_len) 652 return (EINVAL); 653 oldfds = (cm->cmsg_len - sizeof (*cm)) / sizeof (int); 654 rp = (struct file **)(cm + 1); 655 for (i = 0; i < oldfds; i++) { 656 fd = *(int *)rp++; 657 if ((unsigned)fd >= fdp->fd_nfiles || 658 fdp->fd_ofiles[fd] == NULL) 659 return (EBADF); 660 } 661 rp = (struct file **)(cm + 1); 662 for (i = 0; i < oldfds; i++) { 663 fp = fdp->fd_ofiles[*(int *)rp]; 664 *rp++ = fp; 665 fp->f_count++; 666 fp->f_msgcount++; 667 unp_rights++; 668 } 669 return (0); 670 } 671 672 int unp_defer, unp_gcing; 673 extern struct domain unixdomain; 674 675 void 676 unp_gc() 677 { 678 register struct file *fp, *nextfp; 679 register struct socket *so; 680 struct file **extra_ref, **fpp; 681 int nunref, i; 682 683 if (unp_gcing) 684 return; 685 unp_gcing = 1; 686 unp_defer = 0; 687 for (fp = filehead; fp; fp = fp->f_filef) 688 fp->f_flag &= ~(FMARK|FDEFER); 689 do { 690 for (fp = filehead; fp; fp = fp->f_filef) { 691 if (fp->f_count == 0) 692 continue; 693 if (fp->f_flag & FDEFER) { 694 fp->f_flag &= ~FDEFER; 695 unp_defer--; 696 } else { 697 if (fp->f_flag & FMARK) 698 continue; 699 if (fp->f_count == fp->f_msgcount) 700 continue; 701 fp->f_flag |= FMARK; 702 } 703 if (fp->f_type != DTYPE_SOCKET || 704 (so = (struct socket *)fp->f_data) == 0) 705 continue; 706 if (so->so_proto->pr_domain != &unixdomain || 707 (so->so_proto->pr_flags&PR_RIGHTS) == 0) 708 continue; 709 #ifdef notdef 710 if (so->so_rcv.sb_flags & SB_LOCK) { 711 /* 712 * This is problematical; it's not clear 713 * we need to wait for the sockbuf to be 714 * unlocked (on a uniprocessor, at least), 715 * and it's also not clear what to do 716 * if sbwait returns an error due to receipt 717 * of a signal. If sbwait does return 718 * an error, we'll go into an infinite 719 * loop. Delete all of this for now. 720 */ 721 (void) sbwait(&so->so_rcv); 722 goto restart; 723 } 724 #endif 725 unp_scan(so->so_rcv.sb_mb, unp_mark); 726 } 727 } while (unp_defer); 728 /* 729 * We grab an extra reference to each of the file table entries 730 * that are not otherwise accessible and then free the rights 731 * that are stored in messages on them. 732 * 733 * The bug in the orginal code is a little tricky, so I'll describe 734 * what's wrong with it here. 735 * 736 * It is incorrect to simply unp_discard each entry for f_msgcount 737 * times -- consider the case of sockets A and B that contain 738 * references to each other. On a last close of some other socket, 739 * we trigger a gc since the number of outstanding rights (unp_rights) 740 * is non-zero. If during the sweep phase the gc code un_discards, 741 * we end up doing a (full) closef on the descriptor. A closef on A 742 * results in the following chain. Closef calls soo_close, which 743 * calls soclose. Soclose calls first (through the switch 744 * uipc_usrreq) unp_detach, which re-invokes unp_gc. Unp_gc simply 745 * returns because the previous instance had set unp_gcing, and 746 * we return all the way back to soclose, which marks the socket 747 * with SS_NOFDREF, and then calls sofree. Sofree calls sorflush 748 * to free up the rights that are queued in messages on the socket A, 749 * i.e., the reference on B. The sorflush calls via the dom_dispose 750 * switch unp_dispose, which unp_scans with unp_discard. This second 751 * instance of unp_discard just calls closef on B. 752 * 753 * Well, a similar chain occurs on B, resulting in a sorflush on B, 754 * which results in another closef on A. Unfortunately, A is already 755 * being closed, and the descriptor has already been marked with 756 * SS_NOFDREF, and soclose panics at this point. 757 * 758 * Here, we first take an extra reference to each inaccessible 759 * descriptor. Then, we call sorflush ourself, since we know 760 * it is a Unix domain socket anyhow. After we destroy all the 761 * rights carried in messages, we do a last closef to get rid 762 * of our extra reference. This is the last close, and the 763 * unp_detach etc will shut down the socket. 764 * 765 * 91/09/19, bsy (at) cs.cmu.edu 766 */ 767 extra_ref = malloc(nfiles * sizeof(struct file *), M_FILE, M_WAITOK); 768 for (nunref = 0, fp = filehead, fpp = extra_ref; fp; fp = nextfp) { 769 nextfp = fp->f_filef; 770 if (fp->f_count == 0) 771 continue; 772 if (fp->f_count == fp->f_msgcount && !(fp->f_flag & FMARK)) { 773 *fpp++ = fp; 774 nunref++; 775 fp->f_count++; 776 } 777 } 778 for (i = nunref, fpp = extra_ref; --i >= 0; ++fpp) 779 sorflush((struct socket *)(*fpp)->f_data); 780 for (i = nunref, fpp = extra_ref; --i >= 0; ++fpp) 781 closef(*fpp); 782 free((caddr_t)extra_ref, M_FILE); 783 unp_gcing = 0; 784 } 785 786 void 787 unp_dispose(m) 788 struct mbuf *m; 789 { 790 791 if (m) 792 unp_scan(m, unp_discard); 793 } 794 795 void 796 unp_scan(m0, op) 797 register struct mbuf *m0; 798 void (*op) __P((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 } 824 825 void 826 unp_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 } 835 836 void 837 unp_discard(fp) 838 struct file *fp; 839 { 840 841 fp->f_msgcount--; 842 unp_rights--; 843 (void) closef(fp, (struct proc *)NULL); 844 } 845
Indexes created Tue Sep 23 07:09:52 GMT 2025