/* $OpenBSD: uipc_usrreq.c,v 1.73 2014/03/18 06:59:00 guenther Exp $ */ /* $NetBSD: uipc_usrreq.c,v 1.18 1996/02/09 19:00:50 christos Exp $ */ /* * Copyright (c) 1982, 1986, 1989, 1991, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)uipc_usrreq.c 8.3 (Berkeley) 1/4/94 */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include void uipc_setaddr(const struct unpcb *, struct mbuf *); /* * Unix communications domain. * * TODO: * RDM * rethink name space problems * need a proper out-of-band */ struct sockaddr sun_noname = { sizeof(sun_noname), AF_UNIX }; ino_t unp_ino; /* prototype for fake inode numbers */ void uipc_setaddr(const struct unpcb *unp, struct mbuf *nam) { if (unp != NULL && unp->unp_addr != NULL) { nam->m_len = unp->unp_addr->m_len; bcopy(mtod(unp->unp_addr, caddr_t), mtod(nam, caddr_t), nam->m_len); } else { nam->m_len = sizeof(sun_noname); bcopy(&sun_noname, mtod(nam, struct sockaddr *), nam->m_len); } } /*ARGSUSED*/ int uipc_usrreq(struct socket *so, int req, struct mbuf *m, struct mbuf *nam, struct mbuf *control, struct proc *p) { struct unpcb *unp = sotounpcb(so); struct socket *so2; int error = 0; if (req == PRU_CONTROL) return (EOPNOTSUPP); if (req != PRU_SEND && control && control->m_len) { error = EOPNOTSUPP; goto release; } if (unp == NULL && req != PRU_ATTACH) { error = EINVAL; goto release; } switch (req) { case PRU_ATTACH: if (unp) { error = EISCONN; break; } error = unp_attach(so); break; case PRU_DETACH: unp_detach(unp); break; case PRU_BIND: error = unp_bind(unp, nam, p); break; case PRU_LISTEN: if (unp->unp_vnode == NULL) error = EINVAL; break; case PRU_CONNECT: error = unp_connect(so, nam, p); break; case PRU_CONNECT2: error = unp_connect2(so, (struct socket *)nam); break; case PRU_DISCONNECT: unp_disconnect(unp); break; case PRU_ACCEPT: /* * Pass back name of connected socket, * if it was bound and we are still connected * (our peer may have closed already!). */ uipc_setaddr(unp->unp_conn, nam); break; case PRU_SHUTDOWN: socantsendmore(so); unp_shutdown(unp); break; case PRU_RCVD: switch (so->so_type) { case SOCK_DGRAM: panic("uipc 1"); /*NOTREACHED*/ case SOCK_STREAM: case SOCK_SEQPACKET: #define rcv (&so->so_rcv) #define snd (&so2->so_snd) if (unp->unp_conn == NULL) break; so2 = unp->unp_conn->unp_socket; /* * Adjust backpressure on sender * and wakeup any waiting to write. */ snd->sb_mbmax += unp->unp_mbcnt - rcv->sb_mbcnt; unp->unp_mbcnt = rcv->sb_mbcnt; snd->sb_hiwat += unp->unp_cc - rcv->sb_cc; unp->unp_cc = rcv->sb_cc; sowwakeup(so2); #undef snd #undef rcv break; default: panic("uipc 2"); } break; case PRU_SEND: if (control && (error = unp_internalize(control, p))) break; switch (so->so_type) { case SOCK_DGRAM: { struct sockaddr *from; if (nam) { if (unp->unp_conn) { error = EISCONN; break; } error = unp_connect(so, nam, p); if (error) break; } else { if (unp->unp_conn == NULL) { error = ENOTCONN; break; } } so2 = unp->unp_conn->unp_socket; if (unp->unp_addr) from = mtod(unp->unp_addr, struct sockaddr *); else from = &sun_noname; if (sbappendaddr(&so2->so_rcv, from, m, control)) { sorwakeup(so2); m = NULL; control = NULL; } else error = ENOBUFS; if (nam) unp_disconnect(unp); break; } case SOCK_STREAM: case SOCK_SEQPACKET: #define rcv (&so2->so_rcv) #define snd (&so->so_snd) if (so->so_state & SS_CANTSENDMORE) { error = EPIPE; break; } if (unp->unp_conn == NULL) { error = ENOTCONN; break; } so2 = unp->unp_conn->unp_socket; /* * Send to paired receive port, and then reduce * send buffer hiwater marks to maintain backpressure. * Wake up readers. */ if (control) { if (sbappendcontrol(rcv, m, control)) control = NULL; } else if (so->so_type == SOCK_SEQPACKET) sbappendrecord(rcv, m); else sbappend(rcv, m); snd->sb_mbmax -= rcv->sb_mbcnt - unp->unp_conn->unp_mbcnt; unp->unp_conn->unp_mbcnt = rcv->sb_mbcnt; snd->sb_hiwat -= rcv->sb_cc - unp->unp_conn->unp_cc; unp->unp_conn->unp_cc = rcv->sb_cc; sorwakeup(so2); m = NULL; #undef snd #undef rcv break; default: panic("uipc 4"); } /* we need to undo unp_internalize in case of errors */ if (control && error) unp_dispose(control); break; case PRU_ABORT: unp_drop(unp, ECONNABORTED); break; case PRU_SENSE: { struct stat *sb = (struct stat *)m; sb->st_blksize = so->so_snd.sb_hiwat; switch (so->so_type) { case SOCK_STREAM: case SOCK_SEQPACKET: if (unp->unp_conn != NULL) { so2 = unp->unp_conn->unp_socket; sb->st_blksize += so2->so_rcv.sb_cc; } break; default: break; } sb->st_dev = NODEV; if (unp->unp_ino == 0) unp->unp_ino = unp_ino++; sb->st_atim.tv_sec = sb->st_mtim.tv_sec = sb->st_ctim.tv_sec = unp->unp_ctime.tv_sec; sb->st_atim.tv_nsec = sb->st_mtim.tv_nsec = sb->st_ctim.tv_nsec = unp->unp_ctime.tv_nsec; sb->st_ino = unp->unp_ino; return (0); } case PRU_RCVOOB: return (EOPNOTSUPP); case PRU_SENDOOB: error = EOPNOTSUPP; break; case PRU_SOCKADDR: uipc_setaddr(unp, nam); break; case PRU_PEERADDR: uipc_setaddr(unp->unp_conn, nam); break; case PRU_SLOWTIMO: break; default: panic("piusrreq"); } release: if (control) m_freem(control); if (m) m_freem(m); return (error); } /* * Both send and receive buffers are allocated PIPSIZ bytes of buffering * for stream sockets, although the total for sender and receiver is * actually only PIPSIZ. * Datagram sockets really use the sendspace as the maximum datagram size, * and don't really want to reserve the sendspace. Their recvspace should * be large enough for at least one max-size datagram plus address. */ #define PIPSIZ 4096 u_long unpst_sendspace = PIPSIZ; u_long unpst_recvspace = PIPSIZ; u_long unpdg_sendspace = 2*1024; /* really max datagram size */ u_long unpdg_recvspace = 4*1024; int unp_rights; /* file descriptors in flight */ int unp_attach(struct socket *so) { struct unpcb *unp; int error; if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) { switch (so->so_type) { case SOCK_STREAM: case SOCK_SEQPACKET: error = soreserve(so, unpst_sendspace, unpst_recvspace); break; case SOCK_DGRAM: error = soreserve(so, unpdg_sendspace, unpdg_recvspace); break; default: panic("unp_attach"); } if (error) return (error); } unp = malloc(sizeof(*unp), M_PCB, M_NOWAIT|M_ZERO); if (unp == NULL) return (ENOBUFS); unp->unp_socket = so; so->so_pcb = unp; getnanotime(&unp->unp_ctime); return (0); } void unp_detach(struct unpcb *unp) { struct vnode *vp; if (unp->unp_vnode) { unp->unp_vnode->v_socket = NULL; vp = unp->unp_vnode; unp->unp_vnode = NULL; vrele(vp); } if (unp->unp_conn) unp_disconnect(unp); while (unp->unp_refs) unp_drop(unp->unp_refs, ECONNRESET); soisdisconnected(unp->unp_socket); unp->unp_socket->so_pcb = NULL; m_freem(unp->unp_addr); if (unp_rights) { /* * Normally the receive buffer is flushed later, * in sofree, but if our receive buffer holds references * to descriptors that are now garbage, we will dispose * of those descriptor references after the garbage collector * gets them (resulting in a "panic: closef: count < 0"). */ sorflush(unp->unp_socket); free(unp, M_PCB); unp_gc(); } else free(unp, M_PCB); } int unp_bind(struct unpcb *unp, struct mbuf *nam, struct proc *p) { struct sockaddr_un *soun = mtod(nam, struct sockaddr_un *); struct mbuf *nam2; struct vnode *vp; struct vattr vattr; int error; struct nameidata nd; size_t pathlen; if (unp->unp_vnode != NULL) return (EINVAL); if (soun->sun_len > sizeof(struct sockaddr_un) || soun->sun_len < offsetof(struct sockaddr_un, sun_path)) return (EINVAL); if (soun->sun_family != AF_UNIX) return (EAFNOSUPPORT); pathlen = strnlen(soun->sun_path, soun->sun_len - offsetof(struct sockaddr_un, sun_path)); if (pathlen == sizeof(soun->sun_path)) return (EINVAL); nam2 = m_getclr(M_WAITOK, MT_SONAME); nam2->m_len = sizeof(struct sockaddr_un); memcpy(mtod(nam2, struct sockaddr_un *), soun, offsetof(struct sockaddr_un, sun_path) + pathlen); /* No need to NUL terminate: m_getclr() returns bzero'd mbufs. */ soun = mtod(nam2, struct sockaddr_un *); /* Fixup sun_len to keep it in sync with m_len. */ soun->sun_len = nam2->m_len; NDINIT(&nd, CREATE, NOFOLLOW | LOCKPARENT, UIO_SYSSPACE, soun->sun_path, p); /* SHOULD BE ABLE TO ADOPT EXISTING AND wakeup() ALA FIFO's */ if ((error = namei(&nd)) != 0) { m_freem(nam2); return (error); } vp = nd.ni_vp; if (vp != NULL) { VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd); if (nd.ni_dvp == vp) vrele(nd.ni_dvp); else vput(nd.ni_dvp); vrele(vp); m_freem(nam2); return (EADDRINUSE); } VATTR_NULL(&vattr); vattr.va_type = VSOCK; vattr.va_mode = ACCESSPERMS &~ p->p_fd->fd_cmask; error = VOP_CREATE(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &vattr); if (error) { m_freem(nam2); return (error); } unp->unp_addr = nam2; vp = nd.ni_vp; vp->v_socket = unp->unp_socket; unp->unp_vnode = vp; unp->unp_connid.uid = p->p_ucred->cr_uid; unp->unp_connid.gid = p->p_ucred->cr_gid; unp->unp_connid.pid = p->p_p->ps_pid; unp->unp_flags |= UNP_FEIDSBIND; VOP_UNLOCK(vp, 0, p); return (0); } int unp_connect(struct socket *so, struct mbuf *nam, struct proc *p) { struct sockaddr_un *soun = mtod(nam, struct sockaddr_un *); struct vnode *vp; struct socket *so2, *so3; struct unpcb *unp, *unp2, *unp3; int error; struct nameidata nd; if (soun->sun_family != AF_UNIX) return (EAFNOSUPPORT); if (nam->m_len < sizeof(struct sockaddr_un)) *(mtod(nam, caddr_t) + nam->m_len) = 0; else if (nam->m_len > sizeof(struct sockaddr_un)) return (EINVAL); else if (memchr(soun->sun_path, '\0', sizeof(soun->sun_path)) == NULL) return (EINVAL); NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, soun->sun_path, p); if ((error = namei(&nd)) != 0) return (error); vp = nd.ni_vp; if (vp->v_type != VSOCK) { error = ENOTSOCK; goto bad; } if ((error = VOP_ACCESS(vp, VWRITE, p->p_ucred, p)) != 0) goto bad; so2 = vp->v_socket; if (so2 == NULL) { error = ECONNREFUSED; goto bad; } if (so->so_type != so2->so_type) { error = EPROTOTYPE; goto bad; } if (so->so_proto->pr_flags & PR_CONNREQUIRED) { if ((so2->so_options & SO_ACCEPTCONN) == 0 || (so3 = sonewconn(so2, 0)) == 0) { error = ECONNREFUSED; goto bad; } unp = sotounpcb(so); unp2 = sotounpcb(so2); unp3 = sotounpcb(so3); if (unp2->unp_addr) unp3->unp_addr = m_copy(unp2->unp_addr, 0, (int)M_COPYALL); unp3->unp_connid.uid = p->p_ucred->cr_uid; unp3->unp_connid.gid = p->p_ucred->cr_gid; unp3->unp_connid.pid = p->p_p->ps_pid; unp3->unp_flags |= UNP_FEIDS; so2 = so3; if (unp2->unp_flags & UNP_FEIDSBIND) { unp->unp_connid = unp2->unp_connid; unp->unp_flags |= UNP_FEIDS; } } error = unp_connect2(so, so2); bad: vput(vp); return (error); } int unp_connect2(struct socket *so, struct socket *so2) { struct unpcb *unp = sotounpcb(so); struct unpcb *unp2; if (so2->so_type != so->so_type) return (EPROTOTYPE); unp2 = sotounpcb(so2); unp->unp_conn = unp2; switch (so->so_type) { case SOCK_DGRAM: unp->unp_nextref = unp2->unp_refs; unp2->unp_refs = unp; soisconnected(so); break; case SOCK_STREAM: case SOCK_SEQPACKET: unp2->unp_conn = unp; soisconnected(so); soisconnected(so2); break; default: panic("unp_connect2"); } return (0); } void unp_disconnect(struct unpcb *unp) { struct unpcb *unp2 = unp->unp_conn; if (unp2 == NULL) return; unp->unp_conn = NULL; switch (unp->unp_socket->so_type) { case SOCK_DGRAM: if (unp2->unp_refs == unp) unp2->unp_refs = unp->unp_nextref; else { unp2 = unp2->unp_refs; for (;;) { if (unp2 == NULL) panic("unp_disconnect"); if (unp2->unp_nextref == unp) break; unp2 = unp2->unp_nextref; } unp2->unp_nextref = unp->unp_nextref; } unp->unp_nextref = NULL; unp->unp_socket->so_state &= ~SS_ISCONNECTED; break; case SOCK_STREAM: case SOCK_SEQPACKET: soisdisconnected(unp->unp_socket); unp2->unp_conn = NULL; soisdisconnected(unp2->unp_socket); break; } } void unp_shutdown(struct unpcb *unp) { struct socket *so; switch (unp->unp_socket->so_type) { case SOCK_STREAM: case SOCK_SEQPACKET: if (unp->unp_conn && (so = unp->unp_conn->unp_socket)) socantrcvmore(so); break; default: break; } } void unp_drop(struct unpcb *unp, int errno) { struct socket *so = unp->unp_socket; so->so_error = errno; unp_disconnect(unp); if (so->so_head) { so->so_pcb = NULL; sofree(so); m_freem(unp->unp_addr); free(unp, M_PCB); } } #ifdef notdef unp_drain(void) { } #endif int unp_externalize(struct mbuf *rights, socklen_t controllen) { struct proc *p = curproc; /* XXX */ struct cmsghdr *cm = mtod(rights, struct cmsghdr *); int i, *fdp = NULL; struct file **rp; struct file *fp; int nfds, error = 0; nfds = (cm->cmsg_len - CMSG_ALIGN(sizeof(*cm))) / sizeof(struct file *); if (controllen < CMSG_ALIGN(sizeof(struct cmsghdr))) controllen = 0; else controllen -= CMSG_ALIGN(sizeof(struct cmsghdr)); if (nfds > controllen / sizeof(int)) { error = EMSGSIZE; goto restart; } rp = (struct file **)CMSG_DATA(cm); fdp = malloc(nfds * sizeof(int), M_TEMP, M_WAITOK); /* Make sure the recipient should be able to see the descriptors.. */ if (p->p_fd->fd_rdir != NULL) { rp = (struct file **)CMSG_DATA(cm); for (i = 0; i < nfds; i++) { fp = *rp++; /* * No to block devices. If passing a directory, * make sure that it is underneath the root. */ if (fp->f_type == DTYPE_VNODE) { struct vnode *vp = (struct vnode *)fp->f_data; if (vp->v_type == VBLK || (vp->v_type == VDIR && !vn_isunder(vp, p->p_fd->fd_rdir, p))) { error = EPERM; break; } } } } restart: fdplock(p->p_fd); if (error != 0) { rp = ((struct file **)CMSG_DATA(cm)); for (i = 0; i < nfds; i++) { fp = *rp; /* * zero the pointer before calling unp_discard, * since it may end up in unp_gc().. */ *rp++ = NULL; unp_discard(fp); } goto out; } /* * First loop -- allocate file descriptor table slots for the * new descriptors. */ rp = ((struct file **)CMSG_DATA(cm)); for (i = 0; i < nfds; i++) { if ((error = fdalloc(p, 0, &fdp[i])) != 0) { /* * Back out what we've done so far. */ for (--i; i >= 0; i--) fdremove(p->p_fd, fdp[i]); if (error == ENOSPC) { fdexpand(p); error = 0; } else { /* * This is the error that has historically * been returned, and some callers may * expect it. */ error = EMSGSIZE; } fdpunlock(p->p_fd); goto restart; } /* * Make the slot reference the descriptor so that * fdalloc() works properly.. We finalize it all * in the loop below. */ p->p_fd->fd_ofiles[fdp[i]] = *rp++; } /* * Now that adding them has succeeded, update all of the * descriptor passing state. */ rp = (struct file **)CMSG_DATA(cm); for (i = 0; i < nfds; i++) { fp = *rp++; fp->f_msgcount--; unp_rights--; } /* * Copy temporary array to message and adjust length, in case of * transition from large struct file pointers to ints. */ memcpy(CMSG_DATA(cm), fdp, nfds * sizeof(int)); cm->cmsg_len = CMSG_LEN(nfds * sizeof(int)); rights->m_len = CMSG_LEN(nfds * sizeof(int)); out: fdpunlock(p->p_fd); if (fdp) free(fdp, M_TEMP); return (error); } int unp_internalize(struct mbuf *control, struct proc *p) { struct filedesc *fdp = p->p_fd; struct cmsghdr *cm = mtod(control, struct cmsghdr *); struct file **rp, *fp; int i, error; int nfds, *ip, fd, neededspace; /* * Check for two potential msg_controllen values because * IETF stuck their nose in a place it does not belong. */ if (cm->cmsg_type != SCM_RIGHTS || cm->cmsg_level != SOL_SOCKET || !(cm->cmsg_len == control->m_len || control->m_len == CMSG_ALIGN(cm->cmsg_len))) return (EINVAL); nfds = (cm->cmsg_len - CMSG_ALIGN(sizeof(*cm))) / sizeof (int); if (unp_rights + nfds > maxfiles / 10) return (EMFILE); /* Make sure we have room for the struct file pointers */ morespace: neededspace = CMSG_SPACE(nfds * sizeof(struct file *)) - control->m_len; if (neededspace > M_TRAILINGSPACE(control)) { char *tmp; /* if we already have a cluster, the message is just too big */ if (control->m_flags & M_EXT) return (E2BIG); /* copy cmsg data temporarily out of the mbuf */ tmp = malloc(control->m_len, M_TEMP, M_WAITOK); memcpy(tmp, mtod(control, caddr_t), control->m_len); /* allocate a cluster and try again */ MCLGET(control, M_WAIT); if ((control->m_flags & M_EXT) == 0) { free(tmp, M_TEMP); return (ENOBUFS); /* allocation failed */ } /* copy the data back into the cluster */ cm = mtod(control, struct cmsghdr *); memcpy(cm, tmp, control->m_len); free(tmp, M_TEMP); goto morespace; } /* adjust message & mbuf to note amount of space actually used. */ cm->cmsg_len = CMSG_LEN(nfds * sizeof(struct file *)); control->m_len = CMSG_SPACE(nfds * sizeof(struct file *)); ip = ((int *)CMSG_DATA(cm)) + nfds - 1; rp = ((struct file **)CMSG_DATA(cm)) + nfds - 1; for (i = 0; i < nfds; i++) { bcopy(ip, &fd, sizeof fd); ip--; if ((fp = fd_getfile(fdp, fd)) == NULL) { error = EBADF; goto fail; } if (fp->f_count == LONG_MAX-2 || fp->f_msgcount == LONG_MAX-2) { error = EDEADLK; goto fail; } /* kq and systrace descriptors cannot be copied */ if (fp->f_type == DTYPE_KQUEUE || fp->f_type == DTYPE_SYSTRACE) { error = EINVAL; goto fail; } bcopy(&fp, rp, sizeof fp); rp--; fp->f_count++; fp->f_msgcount++; unp_rights++; } return (0); fail: /* Back out what we just did. */ for ( ; i > 0; i--) { rp++; bcopy(rp, &fp, sizeof(fp)); fp->f_count--; fp->f_msgcount--; unp_rights--; } return (error); } int unp_defer, unp_gcing; extern struct domain unixdomain; void unp_gc(void) { struct file *fp, *nextfp; struct socket *so; struct file **extra_ref, **fpp; int nunref, i; if (unp_gcing) return; unp_gcing = 1; unp_defer = 0; LIST_FOREACH(fp, &filehead, f_list) fp->f_iflags &= ~(FIF_MARK|FIF_DEFER); do { LIST_FOREACH(fp, &filehead, f_list) { if (fp->f_iflags & FIF_DEFER) { fp->f_iflags &= ~FIF_DEFER; unp_defer--; } else { if (fp->f_count == 0) continue; if (fp->f_iflags & FIF_MARK) continue; if (fp->f_count == fp->f_msgcount) continue; } fp->f_iflags |= FIF_MARK; if (fp->f_type != DTYPE_SOCKET || (so = fp->f_data) == NULL) continue; if (so->so_proto->pr_domain != &unixdomain || (so->so_proto->pr_flags&PR_RIGHTS) == 0) continue; #ifdef notdef if (so->so_rcv.sb_flags & SB_LOCK) { /* * This is problematical; it's not clear * we need to wait for the sockbuf to be * unlocked (on a uniprocessor, at least), * and it's also not clear what to do * if sbwait returns an error due to receipt * of a signal. If sbwait does return * an error, we'll go into an infinite * loop. Delete all of this for now. */ (void) sbwait(&so->so_rcv); goto restart; } #endif unp_scan(so->so_rcv.sb_mb, unp_mark, 0); } } while (unp_defer); /* * We grab an extra reference to each of the file table entries * that are not otherwise accessible and then free the rights * that are stored in messages on them. * * The bug in the original code is a little tricky, so I'll describe * what's wrong with it here. * * It is incorrect to simply unp_discard each entry for f_msgcount * times -- consider the case of sockets A and B that contain * references to each other. On a last close of some other socket, * we trigger a gc since the number of outstanding rights (unp_rights) * is non-zero. If during the sweep phase the gc code un_discards, * we end up doing a (full) closef on the descriptor. A closef on A * results in the following chain. Closef calls soo_close, which * calls soclose. Soclose calls first (through the switch * uipc_usrreq) unp_detach, which re-invokes unp_gc. Unp_gc simply * returns because the previous instance had set unp_gcing, and * we return all the way back to soclose, which marks the socket * with SS_NOFDREF, and then calls sofree. Sofree calls sorflush * to free up the rights that are queued in messages on the socket A, * i.e., the reference on B. The sorflush calls via the dom_dispose * switch unp_dispose, which unp_scans with unp_discard. This second * instance of unp_discard just calls closef on B. * * Well, a similar chain occurs on B, resulting in a sorflush on B, * which results in another closef on A. Unfortunately, A is already * being closed, and the descriptor has already been marked with * SS_NOFDREF, and soclose panics at this point. * * Here, we first take an extra reference to each inaccessible * descriptor. Then, we call sorflush ourself, since we know * it is a Unix domain socket anyhow. After we destroy all the * rights carried in messages, we do a last closef to get rid * of our extra reference. This is the last close, and the * unp_detach etc will shut down the socket. * * 91/09/19, bsy@cs.cmu.edu */ extra_ref = malloc(nfiles * sizeof(struct file *), M_FILE, M_WAITOK); for (nunref = 0, fp = LIST_FIRST(&filehead), fpp = extra_ref; fp != NULL; fp = nextfp) { nextfp = LIST_NEXT(fp, f_list); if (fp->f_count == 0) continue; if (fp->f_count == fp->f_msgcount && !(fp->f_iflags & FIF_MARK)) { *fpp++ = fp; nunref++; FREF(fp); fp->f_count++; } } for (i = nunref, fpp = extra_ref; --i >= 0; ++fpp) if ((*fpp)->f_type == DTYPE_SOCKET && (*fpp)->f_data != NULL) sorflush((*fpp)->f_data); for (i = nunref, fpp = extra_ref; --i >= 0; ++fpp) (void) closef(*fpp, NULL); free(extra_ref, M_FILE); unp_gcing = 0; } void unp_dispose(struct mbuf *m) { if (m) unp_scan(m, unp_discard, 1); } void unp_scan(struct mbuf *m0, void (*op)(struct file *), int discard) { struct mbuf *m; struct file **rp, *fp; struct cmsghdr *cm; int i; int qfds; while (m0) { for (m = m0; m; m = m->m_next) { if (m->m_type == MT_CONTROL && m->m_len >= sizeof(*cm)) { cm = mtod(m, struct cmsghdr *); if (cm->cmsg_level != SOL_SOCKET || cm->cmsg_type != SCM_RIGHTS) continue; qfds = (cm->cmsg_len - CMSG_ALIGN(sizeof *cm)) / sizeof(struct file *); rp = (struct file **)CMSG_DATA(cm); for (i = 0; i < qfds; i++) { fp = *rp; if (discard) *rp = 0; (*op)(fp); rp++; } break; /* XXX, but saves time */ } } m0 = m0->m_nextpkt; } } void unp_mark(struct file *fp) { if (fp == NULL) return; if (fp->f_iflags & (FIF_MARK|FIF_DEFER)) return; if (fp->f_type == DTYPE_SOCKET) { unp_defer++; fp->f_iflags |= FIF_DEFER; } else { fp->f_iflags |= FIF_MARK; } } void unp_discard(struct file *fp) { if (fp == NULL) return; FREF(fp); fp->f_msgcount--; unp_rights--; (void) closef(fp, NULL); }