Make tun(4) and tap(4) event filters MP-safe.

OK mvs@

diff --git a/sys/net/if_tun.c b/sys/net/if_tun.c
index 88c91c9..b297459 100644 (file)
--- a/sys/net/if_tun.c
+++ b/sys/net/if_tun.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: if_tun.c,v 1.237 2022/07/02 08:50:42 visa Exp $       */
+/*     $OpenBSD: if_tun.c,v 1.238 2023/02/10 14:39:18 visa Exp $       */
 /*     $NetBSD: if_tun.c,v 1.24 1996/05/07 02:40:48 thorpej Exp $      */
 
 /*
@@ -47,13 +47,14 @@
 #include <sys/ioctl.h>
 #include <sys/errno.h>
 #include <sys/syslog.h>
-#include <sys/selinfo.h>
 #include <sys/fcntl.h>
 #include <sys/time.h>
 #include <sys/device.h>
 #include <sys/vnode.h>
 #include <sys/signalvar.h>
 #include <sys/conf.h>
+#include <sys/event.h>
+#include <sys/mutex.h>
 #include <sys/smr.h>
 
 #include <net/if.h>
@@ -78,8 +79,9 @@
 struct tun_softc {
        struct arpcom           sc_ac;          /* ethernet common data */
 #define sc_if                  sc_ac.ac_if
-       struct selinfo          sc_rsel;        /* read select */
-       struct selinfo          sc_wsel;        /* write select (not used) */
+       struct mutex            sc_mtx;
+       struct klist            sc_rklist;      /* knotes for read */
+       struct klist            sc_wklist;      /* knotes for write (unused) */
        SMR_LIST_ENTRY(tun_softc)
                                sc_entry;       /* all tunnel interfaces */
        int                     sc_unit;
@@ -125,22 +127,28 @@ int       tun_init(struct tun_softc *);
 void   tun_start(struct ifnet *);
 int    filt_tunread(struct knote *, long);
 int    filt_tunwrite(struct knote *, long);
+int    filt_tunmodify(struct kevent *, struct knote *);
+int    filt_tunprocess(struct knote *, struct kevent *);
 void   filt_tunrdetach(struct knote *);
 void   filt_tunwdetach(struct knote *);
 void   tun_link_state(struct ifnet *, int);
 
 const struct filterops tunread_filtops = {
-       .f_flags        = FILTEROP_ISFD,
+       .f_flags        = FILTEROP_ISFD | FILTEROP_MPSAFE,
        .f_attach       = NULL,
        .f_detach       = filt_tunrdetach,
        .f_event        = filt_tunread,
+       .f_modify       = filt_tunmodify,
+       .f_process      = filt_tunprocess,
 };
 
 const struct filterops tunwrite_filtops = {
-       .f_flags        = FILTEROP_ISFD,
+       .f_flags        = FILTEROP_ISFD | FILTEROP_MPSAFE,
        .f_attach       = NULL,
        .f_detach       = filt_tunwdetach,
        .f_event        = filt_tunwrite,
+       .f_modify       = filt_tunmodify,
+       .f_process      = filt_tunprocess,
 };
 
 SMR_LIST_HEAD(tun_list, tun_softc);
@@ -220,6 +228,9 @@ tun_create(struct if_clone *ifc, int unit, int flags)
        ifp = &sc->sc_if;
        snprintf(ifp->if_xname, sizeof(ifp->if_xname),
            "%s%d", ifc->ifc_name, unit);
+       mtx_init(&sc->sc_mtx, IPL_NET);
+       klist_init_mutex(&sc->sc_rklist, &sc->sc_mtx);
+       klist_init_mutex(&sc->sc_wklist, &sc->sc_mtx);
        ifp->if_softc = sc;
 
        /* this is enough state for tun_dev_open to work with */
@@ -275,6 +286,8 @@ tun_create(struct if_clone *ifc, int unit, int flags)
        return (0);
 
 exists:
+       klist_free(&sc->sc_rklist);
+       klist_free(&sc->sc_wklist);
        free(sc, M_DEVBUF, sizeof(*sc));
        return (EEXIST);
 }
@@ -284,7 +297,6 @@ tun_clone_destroy(struct ifnet *ifp)
 {
        struct tun_softc        *sc = ifp->if_softc;
        dev_t                    dev;
-       int                      s;
 
        KERNEL_ASSERT_LOCKED();
 
@@ -314,10 +326,11 @@ tun_clone_destroy(struct ifnet *ifp)
        /* wait for device entrypoints to finish */
        refcnt_finalize(&sc->sc_refs, "tundtor");
 
-       s = splhigh();
-       klist_invalidate(&sc->sc_rsel.si_note);
-       klist_invalidate(&sc->sc_wsel.si_note);
-       splx(s);
+       klist_invalidate(&sc->sc_rklist);
+       klist_invalidate(&sc->sc_wklist);
+
+       klist_free(&sc->sc_rklist);
+       klist_free(&sc->sc_wklist);
 
        if (ISSET(sc->sc_flags, TUN_LAYER2))
                ether_ifdetach(ifp);
@@ -488,7 +501,6 @@ tun_dev_close(dev_t dev, struct proc *p)
        ifq_purge(&ifp->if_snd);
 
        CLR(sc->sc_flags, TUN_ASYNC);
-       selwakeup(&sc->sc_rsel);
        sigio_free(&sc->sc_sigio);
 
        if (!ISSET(sc->sc_flags, TUN_DEAD)) {
@@ -654,7 +666,8 @@ tun_wakeup(struct tun_softc *sc)
        if (sc->sc_reading)
                wakeup(&sc->sc_if.if_snd);
 
-       selwakeup(&sc->sc_rsel);
+       knote(&sc->sc_rklist, 0);
+
        if (sc->sc_flags & TUN_ASYNC)
                pgsigio(&sc->sc_sigio, SIGIO, 0);
 }
@@ -960,7 +973,6 @@ tun_dev_kqfilter(dev_t dev, struct knote *kn)
        struct ifnet            *ifp;
        struct klist            *klist;
        int                      error = 0;
-       int                      s;
 
        sc = tun_get(dev);
        if (sc == NULL)
@@ -970,11 +982,11 @@ tun_dev_kqfilter(dev_t dev, struct knote *kn)
 
        switch (kn->kn_filter) {
        case EVFILT_READ:
-               klist = &sc->sc_rsel.si_note;
+               klist = &sc->sc_rklist;
                kn->kn_fop = &tunread_filtops;
                break;
        case EVFILT_WRITE:
-               klist = &sc->sc_wsel.si_note;
+               klist = &sc->sc_wklist;
                kn->kn_fop = &tunwrite_filtops;
                break;
        default:
@@ -982,11 +994,9 @@ tun_dev_kqfilter(dev_t dev, struct knote *kn)
                goto put;
        }
 
-       kn->kn_hook = (caddr_t)sc; /* XXX give the sc_ref to the hook? */
+       kn->kn_hook = sc;
 
-       s = splhigh();
-       klist_insert_locked(klist, kn);
-       splx(s);
+       klist_insert(klist, kn);
 
 put:
        tun_put(sc);
@@ -996,12 +1006,9 @@ put:
 void
 filt_tunrdetach(struct knote *kn)
 {
-       int                      s;
        struct tun_softc        *sc = kn->kn_hook;
 
-       s = splhigh();
-       klist_remove_locked(&sc->sc_rsel.si_note, kn);
-       splx(s);
+       klist_remove(&sc->sc_rklist, kn);
 }
 
 int
@@ -1010,6 +1017,8 @@ filt_tunread(struct knote *kn, long hint)
        struct tun_softc        *sc = kn->kn_hook;
        struct ifnet            *ifp = &sc->sc_if;
 
+       MUTEX_ASSERT_LOCKED(&sc->sc_mtx);
+
        kn->kn_data = ifq_hdatalen(&ifp->if_snd);
 
        return (kn->kn_data > 0);
@@ -1018,12 +1027,9 @@ filt_tunread(struct knote *kn, long hint)
 void
 filt_tunwdetach(struct knote *kn)
 {
-       int                      s;
        struct tun_softc        *sc = kn->kn_hook;
 
-       s = splhigh();
-       klist_remove_locked(&sc->sc_wsel.si_note, kn);
-       splx(s);
+       klist_remove(&sc->sc_wklist, kn);
 }
 
 int
@@ -1032,11 +1038,39 @@ filt_tunwrite(struct knote *kn, long hint)
        struct tun_softc        *sc = kn->kn_hook;
        struct ifnet            *ifp = &sc->sc_if;
 
+       MUTEX_ASSERT_LOCKED(&sc->sc_mtx);
+
        kn->kn_data = ifp->if_hdrlen + ifp->if_hardmtu;
 
        return (1);
 }
 
+int
+filt_tunmodify(struct kevent *kev, struct knote *kn)
+{
+       struct tun_softc        *sc = kn->kn_hook;
+       int                      active;
+
+       mtx_enter(&sc->sc_mtx);
+       active = knote_modify(kev, kn);
+       mtx_leave(&sc->sc_mtx);
+
+       return (active);
+}
+
+int
+filt_tunprocess(struct knote *kn, struct kevent *kev)
+{
+       struct tun_softc        *sc = kn->kn_hook;
+       int                      active;
+
+       mtx_enter(&sc->sc_mtx);
+       active = knote_process(kn, kev);
+       mtx_leave(&sc->sc_mtx);
+
+       return (active);
+}
+
 void
 tun_start(struct ifnet *ifp)
 {