/* $NetBSD: if_tap_lkm.c,v 1.3 2008/04/29 05:46:09 martin Exp $ */ /* * Copyright (c) 2003, 2004, 2005 The NetBSD Foundation. * All rights reserved. * * This code is derived from software contributed to the NetBSD Foundation * by Quentin Garnier. * * 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. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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. */ /* * tap is a NetBSD Loadable Kernel Module that demonstrates the use of * several kernel mechanisms, mostly in the networking subsytem. * * 1. it is example LKM, with the standard LKM management routines and * 2. example Ethernet driver. * 3. example of use of autoconf stuff inside a LKM. * 4. example clonable network interface. * 5. example sysctl interface use from a LKM. * 6. example LKM character device, with read, write, ioctl, poll * and kqueue available. * 7. example cloning device, using the MOVEFD semantics. * */ #include __KERNEL_RCSID(0, "$NetBSD: if_tap_lkm.c,v 1.3 2008/04/29 05:46:09 martin Exp $"); #include #include #include #include #include #include #include #include #include #include /* autoconf(9) structures */ CFDRIVER_DECL(tap, DV_DULL, NULL); /* LKM management routines */ int tap_lkmentry(struct lkm_table *, int, int); static int tap_lkmload(struct lkm_table *, int); static int tap_lkmunload(struct lkm_table *, int); void tapattach(int); int tapdetach(void); SYSCTL_SETUP_PROTO(sysctl_tap_setup); extern struct cfattach tap_ca; extern const struct cdevsw tap_cdevsw; extern struct if_clone tap_cloners; static struct sysctllog *tap_log; /* * The type of the module is actually userland-oriented. For a * traditional Ethernet driver, MOD_MISC would be enough since * the userland manipulates interfaces through operations on * sockets. * * Here MOD_DEV is chosen because a direct access interface is * exposed, and the easiest way to achieve this is through a * regular device node. */ MOD_DEV("tap", "tap", NULL, -1, &tap_cdevsw, -1); /* We don't have anything to do on 'modstat' */ int tap_lkmentry(struct lkm_table *lkmtp, int cmd, int ver) { DISPATCH(lkmtp, cmd, ver, tap_lkmload, tap_lkmunload, lkm_nofunc); } /* * autoconf(9) is a rather complicated piece of work, but in the end * it is rather flexible, so you can easily add a device somewhere in * the tree, and make almost anything attach to something known. * * Here the idea is taken from Jason R. Thorpe's ataraid(4) pseudo- * device. Instead of needing a declaration in the kernel * configuration, we teach autoconf(9) the availability of the * pseudo-device at run time. * * Once our autoconf(9) structures are committed to the kernel's * arrays, we can attach a device. It is done through config_attach * for a real device, but for a pseudo-device it is a bit different * and one has to use config_pseudo_attach. * * And since we want the user to be responsible for creating device, * we use the interface cloning mechanism, and advertise our interface * to the kernel. */ static int tap_lkmload(struct lkm_table *lkmtp, int cmd) { int error = 0; error = config_cfdriver_attach(&tap_cd); if (error) { aprint_error("%s: unable to register cfdriver\n", tap_cd.cd_name); goto out; } /* XXX: no way to detect an error for config_cfattach_attach() */ tapattach(1); sysctl_tap_setup(&tap_log); out: return error; } /* * Cleaning up is the most critical part of a LKM, since a module is not * actually made to be loadable, but rather "unloadable". If it is only * to be loaded, you'd better link it to the kernel in the first place. * * The interface cloning mechanism is really simple, with only two void * returning functions. It will always do its job. You should note though * that if an instance of tap can't be detached, the module won't * unload and you won't be able to create interfaces anymore. * * We have to make sure the devices really exist, because they can be * destroyed through ifconfig, hence the test whether cd_devs[i] is NULL * or not. * * The cd_devs array is somehow the downside of the whole autoconf(9) * mechanism, since if you only create 'tap150', you'll get an array of * 150 elements which 149 of them are NULL. */ static int tap_lkmunload(struct lkm_table *lkmtp, int cmd) { int error, i; if_clone_detach(&tap_cloners); for (i = 0; i < tap_cd.cd_ndevs; i++) if (tap_cd.cd_devs[i] != NULL && (error = config_detach(tap_cd.cd_devs[i], 0)) != 0) { aprint_error("%s: unable to detach instance\n", ((struct device *)tap_cd.cd_devs[i])->dv_xname); return error; } sysctl_teardown(&tap_log); if ((error = config_cfattach_detach(tap_cd.cd_name, &tap_ca)) != 0) { aprint_error("%s: unable to deregister cfattach\n", tap_cd.cd_name); return error; } if ((error = config_cfdriver_detach(&tap_cd)) != 0) { aprint_error("%s: unable to deregister cfdriver\n", tap_cd.cd_name); return error; } return 0; }