Author: kevans
Date: Thu Oct 3 17:54:00 2019
New Revision: 353057
URL: https://svnweb.freebsd.org/changeset/base/353057
Log:
if_tuntap: create /dev aliases when a tuntap device gets renamed
Currently, if you do:
$ ifconfig tun0 create
$ ifconfig tun0 name wg0
$ ls -l /dev | egrep 'wg|tun'
You will see tun0, but no wg0. In fact, it's slightly more annoying to make
the association between the new name and the old name in order to open the
device (if it hadn't been opened during the rename).
Register an eventhandler for ifnet_arrival_events and catch interface
renames. We can determine if the ifnet is a tun easily enough from the
if_dname, which matches the cevsw.d_name from the associated tuntap_driver.
Some locking dance is required because renames don't require the device to
be opened, so it could go away in the middle of handling the ioctl, but as
soon as we've verified this isn't the case we can attempt to busy the tun
and either bail out if the tun device is dying, or we can proceed with the
rename.
We only create these aliases on a best-effort basis. Renaming a tun device
to "usbctl", which doesn't exist as an ifnet but does as a /dev, is clearly
not that disastrous, but we can't and won't create a /dev for that.
Modified:
head/sys/net/if_tuntap.c
Modified: head/sys/net/if_tuntap.c
==
--- head/sys/net/if_tuntap.cThu Oct 3 17:46:27 2019(r353056)
+++ head/sys/net/if_tuntap.cThu Oct 3 17:54:00 2019(r353057)
@@ -106,6 +106,7 @@ struct tuntap_driver;
*/
struct tuntap_softc {
TAILQ_ENTRY(tuntap_softc)tun_list;
+ struct cdev *tun_alias;
struct cdev *tun_dev;
u_short tun_flags; /* misc flags */
#defineTUN_OPEN0x0001
@@ -149,7 +150,8 @@ struct tuntap_softc {
* which are static after setup.
*/
static struct mtx tunmtx;
-static eventhandler_tag tag;
+static eventhandler_tag arrival_tag;
+static eventhandler_tag clone_tag;
static const char tunname[] = "tun";
static const char tapname[] = "tap";
static const char vmnetname[] = "vmnet";
@@ -193,6 +195,7 @@ static int tuntap_name2info(const char *name, int *uni
static voidtunclone(void *arg, struct ucred *cred, char *name,
int namelen, struct cdev **dev);
static voidtuncreate(struct cdev *dev, struct tuntap_driver *);
+static voidtunrename(void *arg, struct ifnet *ifp);
static int tunifioctl(struct ifnet *, u_long, caddr_t);
static voidtuninit(struct ifnet *);
static voidtunifinit(void *xtp);
@@ -604,6 +607,7 @@ tun_destroy(struct tuntap_softc *tp)
CURVNET_SET(TUN2IFP(tp)->if_vnet);
+ /* destroy_dev will take care of any alias. */
destroy_dev(tp->tun_dev);
seldrain(>tun_rsel);
knlist_clear(>tun_rsel.si_note, 0);
@@ -682,7 +686,8 @@ tun_uninit(const void *unused __unused)
struct tuntap_softc *tp;
int i;
- EVENTHANDLER_DEREGISTER(dev_clone, tag);
+ EVENTHANDLER_DEREGISTER(ifnet_arrival_event, arrival_tag);
+ EVENTHANDLER_DEREGISTER(dev_clone, clone_tag);
drain_dev_clone_events();
mtx_lock();
@@ -702,6 +707,24 @@ tun_uninit(const void *unused __unused)
}
SYSUNINIT(tun_uninit, SI_SUB_PROTO_IF, SI_ORDER_ANY, tun_uninit, NULL);
+static struct tuntap_driver *
+tuntap_driver_from_ifnet(const struct ifnet *ifp)
+{
+ struct tuntap_driver *drv;
+ int i;
+
+ if (ifp == NULL)
+ return (NULL);
+
+ for (i = 0; i < nitems(tuntap_drivers); ++i) {
+ drv = _drivers[i];
+ if (strcmp(ifp->if_dname, drv->cdevsw.d_name) == 0)
+ return (drv);
+ }
+
+ return (NULL);
+}
+
static int
tuntapmodevent(module_t mod, int type, void *data)
{
@@ -716,9 +739,13 @@ tuntapmodevent(module_t mod, int type, void *data)
clone_setup(>clones);
drv->unrhdr = new_unrhdr(0, IF_MAXUNIT, );
}
- tag = EVENTHANDLER_REGISTER(dev_clone, tunclone, 0, 1000);
- if (tag == NULL)
+ arrival_tag = EVENTHANDLER_REGISTER(ifnet_arrival_event,
+ tunrename, 0, 1000);
+ if (arrival_tag == NULL)
return (ENOMEM);
+ clone_tag = EVENTHANDLER_REGISTER(dev_clone, tunclone, 0, 1000);
+ if (clone_tag == NULL)
+ return (ENOMEM);
break;
case MOD_UNLOAD:
/* See tun_uninit, so it's done after the vnet_sysuninit() */
@@ -900,6 +927,57 @@ tuncreate(struct cdev *dev, struct tuntap_driver *drv)
TUNDEBUG(ifp, "interface %s is created, minor = %#x\n",
ifp->if_xname, dev2unit(dev));
+}
+
+static void
+tunrename(void *arg __unused, struct
