Fix panic on attaching to non-existent interface (introduced by r233937, pointed by hrs@)
Fix panic on tcpdump being attached to interface being removed (introduced by r233937, pointed by hrs@ and adrian@) Protect most of bpf_setf() by BPF global lock Add several forgotten assertions (thanks to adrian@) Document current locking model inside bpf.c Document EVENTHANDLER(9) usage inside BPF. Approved by: kib(mentor) Tested by: gnn MFC in: 4 weeks
This commit is contained in:
parent
fed7420ced
commit
6c74ff0ea6
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=235744
@ -23,7 +23,7 @@
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.\" SUCH DAMAGE.
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.\" $FreeBSD$
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.\"
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.Dd January 7, 2005
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.Dd May 11, 2012
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.Dt EVENTHANDLER 9
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.Os
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.Sh NAME
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@ -197,6 +197,8 @@ Callbacks invoked when an interface is cloned.
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Callbacks invoked when a new network interface appears.
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.It Vt ifnet_departure_event
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Callbacks invoked when a network interface is taken down.
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.It Vt bpf_track
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Callbacks invoked when a BPF listener attaches to/detaches from network interface.
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.It Vt power_profile_change
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Callbacks invoked when the power profile of the system changes.
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.It Vt process_exec
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@ -24,7 +24,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd December 13, 2006
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.Dd May 11, 2012
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.Dt BPF 9
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.Os
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.\"
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@ -246,9 +246,31 @@ The
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function
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returns 0 when the program is not a valid filter program.
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.\"
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.Sh EVENT HANDLERS
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.Nm
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invokes
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.Fa bpf_track
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.Xr EVENTHANDLER 9
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event each time listener attaches to or detaches from an interface.
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Pointer to
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.Pq Vt "struct ifnet *"
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is passed as the first argument, interface
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.Fa dlt
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follows. Last argument indicates listener is attached (1) or
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detached (0).
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Note that handler is invoked with
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.Nm
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global lock held, which implies restriction on sleeping and calling
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.Nm
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subsystem inside
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.Xr EVENTHANDLER 9
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dispatcher.
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Note that handler is not called for write-only listeners.
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.\"
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.Sh SEE ALSO
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.Xr tcpdump 1 ,
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.Xr bpf 4
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.Xr bpf 4 ,
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.Xr EVENTHANDLER 9
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.\"
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.Sh HISTORY
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The Enet packet filter was created in 1980 by Mike Accetta and
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166
sys/net/bpf.c
166
sys/net/bpf.c
@ -147,6 +147,7 @@ static int bpf_bpfd_cnt;
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static void bpf_attachd(struct bpf_d *, struct bpf_if *);
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static void bpf_detachd(struct bpf_d *);
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static void bpf_detachd_locked(struct bpf_d *);
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static void bpf_freed(struct bpf_d *);
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static int bpf_movein(struct uio *, int, struct ifnet *, struct mbuf **,
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struct sockaddr *, int *, struct bpf_insn *);
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@ -206,6 +207,35 @@ static struct filterops bpfread_filtops = {
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.f_event = filt_bpfread,
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};
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/*
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* LOCKING MODEL USED BY BPF:
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* Locks:
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* 1) global lock (BPF_LOCK). Mutex, used to protect interface addition/removal,
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* some global counters and every bpf_if reference.
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* 2) Interface lock. Rwlock, used to protect list of BPF descriptors and their filters.
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* 3) Descriptor lock. Rwlock, used to protect BPF buffers and various structure fields
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* used by bpf_mtap code.
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*
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* Lock order:
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*
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* Global lock, interface lock, descriptor lock
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*
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* We have to acquire interface lock before descriptor main lock due to BPF_MTAP[2]
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* working model. In many places (like bpf_detachd) we start with BPF descriptor
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* (and we need to at least rlock it to get reliable interface pointer). This
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* gives us potential LOR. As a result, we use global lock to protect from bpf_if
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* change in every such place.
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*
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* Changing d->bd_bif is protected by 1) global lock, 2) interface lock and
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* 3) descriptor main wlock.
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* Reading bd_bif can be protected by any of these locks, typically global lock.
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*
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* Changing read/write BPF filter is protected by the same three locks,
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* the same applies for reading.
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*
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* Sleeping in global lock is not allowed due to bpfdetach() using it.
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*/
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/*
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* Wrapper functions for various buffering methods. If the set of buffer
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* modes expands, we will probably want to introduce a switch data structure
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@ -577,6 +607,18 @@ bpf_movein(struct uio *uio, int linktype, struct ifnet *ifp, struct mbuf **mp,
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static void
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bpf_attachd(struct bpf_d *d, struct bpf_if *bp)
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{
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int op_w;
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BPF_LOCK_ASSERT();
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/*
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* Save sysctl value to protect from sysctl change
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* between reads
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*/
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op_w = V_bpf_optimize_writers;
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if (d->bd_bif != NULL)
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bpf_detachd_locked(d);
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/*
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* Point d at bp, and add d to the interface's list.
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* Since there are many applicaiotns using BPF for
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@ -584,11 +626,13 @@ bpf_attachd(struct bpf_d *d, struct bpf_if *bp)
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* we can delay adding d to the list of active listeners until
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* some filter is configured.
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*/
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d->bd_bif = bp;
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BPFIF_WLOCK(bp);
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BPFD_WLOCK(d);
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if (V_bpf_optimize_writers != 0) {
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d->bd_bif = bp;
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if (op_w != 0) {
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/* Add to writers-only list */
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LIST_INSERT_HEAD(&bp->bif_wlist, d, bd_next);
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/*
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@ -600,16 +644,15 @@ bpf_attachd(struct bpf_d *d, struct bpf_if *bp)
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} else
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LIST_INSERT_HEAD(&bp->bif_dlist, d, bd_next);
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BPFD_WUNLOCK(d);
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BPFIF_WUNLOCK(bp);
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BPF_LOCK();
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bpf_bpfd_cnt++;
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BPF_UNLOCK();
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CTR3(KTR_NET, "%s: bpf_attach called by pid %d, adding to %s list",
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__func__, d->bd_pid, d->bd_writer ? "writer" : "active");
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if (V_bpf_optimize_writers == 0)
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if (op_w == 0)
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EVENTHANDLER_INVOKE(bpf_track, bp->bif_ifp, bp->bif_dlt, 1);
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}
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@ -622,8 +665,21 @@ bpf_upgraded(struct bpf_d *d)
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{
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struct bpf_if *bp;
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BPF_LOCK_ASSERT();
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bp = d->bd_bif;
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/*
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* Filter can be set several times without specifying interface.
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* Mark d as reader and exit.
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*/
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if (bp == NULL) {
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BPFD_WLOCK(d);
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d->bd_writer = 0;
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BPFD_WUNLOCK(d);
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return;
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}
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BPFIF_WLOCK(bp);
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BPFD_WLOCK(d);
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@ -646,6 +702,14 @@ bpf_upgraded(struct bpf_d *d)
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*/
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static void
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bpf_detachd(struct bpf_d *d)
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{
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BPF_LOCK();
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bpf_detachd_locked(d);
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BPF_UNLOCK();
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}
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static void
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bpf_detachd_locked(struct bpf_d *d)
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{
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int error;
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struct bpf_if *bp;
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@ -655,7 +719,10 @@ bpf_detachd(struct bpf_d *d)
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BPF_LOCK_ASSERT();
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bp = d->bd_bif;
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/* Check if descriptor is attached */
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if ((bp = d->bd_bif) == NULL)
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return;
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BPFIF_WLOCK(bp);
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BPFD_WLOCK(d);
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@ -672,7 +739,6 @@ bpf_detachd(struct bpf_d *d)
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BPFD_WUNLOCK(d);
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BPFIF_WUNLOCK(bp);
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/* We're already protected by global lock. */
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bpf_bpfd_cnt--;
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/* Call event handler iff d is attached */
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@ -716,10 +782,7 @@ bpf_dtor(void *data)
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d->bd_state = BPF_IDLE;
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BPFD_WUNLOCK(d);
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funsetown(&d->bd_sigio);
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BPF_LOCK();
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if (d->bd_bif)
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bpf_detachd(d);
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BPF_UNLOCK();
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#ifdef MAC
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mac_bpfdesc_destroy(d);
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#endif /* MAC */
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@ -959,6 +1022,7 @@ bpfwrite(struct cdev *dev, struct uio *uio, int ioflag)
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BPF_PID_REFRESH_CUR(d);
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d->bd_wcount++;
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/* XXX: locking required */
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if (d->bd_bif == NULL) {
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d->bd_wdcount++;
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return (ENXIO);
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@ -979,6 +1043,7 @@ bpfwrite(struct cdev *dev, struct uio *uio, int ioflag)
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bzero(&dst, sizeof(dst));
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m = NULL;
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hlen = 0;
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/* XXX: bpf_movein() can sleep */
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error = bpf_movein(uio, (int)d->bd_bif->bif_dlt, ifp,
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&m, &dst, &hlen, d->bd_wfilter);
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if (error) {
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@ -1298,10 +1363,12 @@ bpfioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags,
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* Set data link type.
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*/
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case BIOCSDLT:
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BPF_LOCK();
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if (d->bd_bif == NULL)
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error = EINVAL;
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else
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error = bpf_setdlt(d, *(u_int *)addr);
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BPF_UNLOCK();
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break;
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/*
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@ -1323,7 +1390,9 @@ bpfioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags,
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* Set interface.
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*/
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case BIOCSETIF:
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BPF_LOCK();
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error = bpf_setif(d, (struct ifreq *)addr);
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BPF_UNLOCK();
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break;
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/*
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@ -1609,6 +1678,23 @@ bpf_setf(struct bpf_d *d, struct bpf_program *fp, u_long cmd)
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cmd = BIOCSETWF;
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}
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#endif
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/*
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* Check new filter validness before acquiring any locks.
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* Allocate memory for new filter, if needed.
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*/
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flen = fp->bf_len;
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if ((flen > bpf_maxinsns) || ((fp->bf_insns == NULL) && (flen != 0)))
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return (EINVAL);
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need_upgrade = 0;
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size = flen * sizeof(*fp->bf_insns);
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if (size > 0)
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fcode = (struct bpf_insn *)malloc(size, M_BPF, M_WAITOK);
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else
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fcode = NULL; /* Make compiler happy */
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BPF_LOCK();
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if (cmd == BIOCSETWF) {
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old = d->bd_wfilter;
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wfilter = 1;
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@ -1623,12 +1709,11 @@ bpf_setf(struct bpf_d *d, struct bpf_program *fp, u_long cmd)
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#endif
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}
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if (fp->bf_insns == NULL) {
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if (fp->bf_len != 0)
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return (EINVAL);
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/*
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* Protect filter change by interface lock, too.
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* The same lock order is used by bpf_detachd().
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* Protect filter removal by interface lock.
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* Additionally, we are protected by global lock here.
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*/
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if (d->bd_bif != NULL)
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BPFIF_WLOCK(d->bd_bif);
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BPFD_WLOCK(d);
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if (wfilter)
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@ -1642,6 +1727,7 @@ bpf_setf(struct bpf_d *d, struct bpf_program *fp, u_long cmd)
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reset_d(d);
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}
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BPFD_WUNLOCK(d);
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if (d->bd_bif != NULL)
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BPFIF_WUNLOCK(d->bd_bif);
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if (old != NULL)
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free((caddr_t)old, M_BPF);
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@ -1649,21 +1735,17 @@ bpf_setf(struct bpf_d *d, struct bpf_program *fp, u_long cmd)
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if (ofunc != NULL)
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bpf_destroy_jit_filter(ofunc);
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#endif
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BPF_UNLOCK();
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return (0);
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}
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flen = fp->bf_len;
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if (flen > bpf_maxinsns)
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return (EINVAL);
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need_upgrade = 0;
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size = flen * sizeof(*fp->bf_insns);
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fcode = (struct bpf_insn *)malloc(size, M_BPF, M_WAITOK);
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if (copyin((caddr_t)fp->bf_insns, (caddr_t)fcode, size) == 0 &&
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bpf_validate(fcode, (int)flen)) {
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/*
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* Protect filter change by interface lock, too
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* The same lock order is used by bpf_detachd().
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* Protect filter change by interface lock
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* Additionally, we are protected by global lock here.
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*/
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if (d->bd_bif != NULL)
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BPFIF_WLOCK(d->bd_bif);
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BPFD_WLOCK(d);
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if (wfilter)
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@ -1687,6 +1769,7 @@ bpf_setf(struct bpf_d *d, struct bpf_program *fp, u_long cmd)
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__func__, d->bd_pid, d->bd_writer, need_upgrade);
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}
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BPFD_WUNLOCK(d);
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if (d->bd_bif != NULL)
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BPFIF_WUNLOCK(d->bd_bif);
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if (old != NULL)
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free((caddr_t)old, M_BPF);
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@ -1699,9 +1782,11 @@ bpf_setf(struct bpf_d *d, struct bpf_program *fp, u_long cmd)
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if (need_upgrade != 0)
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bpf_upgraded(d);
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BPF_UNLOCK();
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return (0);
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}
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free((caddr_t)fcode, M_BPF);
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BPF_UNLOCK();
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return (EINVAL);
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}
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@ -1716,6 +1801,8 @@ bpf_setif(struct bpf_d *d, struct ifreq *ifr)
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struct bpf_if *bp;
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struct ifnet *theywant;
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BPF_LOCK_ASSERT();
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theywant = ifunit(ifr->ifr_name);
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if (theywant == NULL || theywant->if_bpf == NULL)
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return (ENXIO);
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@ -1746,15 +1833,8 @@ bpf_setif(struct bpf_d *d, struct ifreq *ifr)
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default:
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panic("bpf_setif: bufmode %d", d->bd_bufmode);
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}
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if (bp != d->bd_bif) {
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if (d->bd_bif)
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/*
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* Detach if attached to something else.
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*/
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bpf_detachd(d);
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if (bp != d->bd_bif)
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bpf_attachd(d, bp);
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}
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BPFD_WLOCK(d);
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reset_d(d);
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BPFD_WUNLOCK(d);
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@ -2362,9 +2442,8 @@ bpfattach2(struct ifnet *ifp, u_int dlt, u_int hdrlen, struct bpf_if **driverp)
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/*
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* Detach bpf from an interface. This involves detaching each descriptor
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* associated with the interface, and leaving bd_bif NULL. Notify each
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* descriptor as it's detached so that any sleepers wake up and get
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* ENXIO.
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* associated with the interface. Notify each descriptor as it's detached
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* so that any sleepers wake up and get ENXIO.
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*/
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void
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bpfdetach(struct ifnet *ifp)
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@ -2398,6 +2477,13 @@ bpfdetach(struct ifnet *ifp)
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bpf_wakeup(d);
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BPFD_WUNLOCK(d);
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}
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/* Free writer-only descriptors */
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while ((d = LIST_FIRST(&bp->bif_wlist)) != NULL) {
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bpf_detachd(d);
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BPFD_WLOCK(d);
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bpf_wakeup(d);
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BPFD_WUNLOCK(d);
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}
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rw_destroy(&bp->bif_lock);
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free(bp, M_BPF);
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}
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@ -2451,18 +2537,19 @@ bpf_setdlt(struct bpf_d *d, u_int dlt)
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struct ifnet *ifp;
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struct bpf_if *bp;
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BPF_LOCK_ASSERT();
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if (d->bd_bif->bif_dlt == dlt)
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return (0);
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ifp = d->bd_bif->bif_ifp;
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BPF_LOCK();
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LIST_FOREACH(bp, &bpf_iflist, bif_next) {
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if (bp->bif_ifp == ifp && bp->bif_dlt == dlt)
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break;
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}
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BPF_UNLOCK();
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if (bp != NULL) {
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opromisc = d->bd_promisc;
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bpf_detachd(d);
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bpf_attachd(d, bp);
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BPFD_WLOCK(d);
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reset_d(d);
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@ -2522,6 +2609,9 @@ bpf_zero_counters(void)
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BPF_UNLOCK();
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}
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/*
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* Fill filter statistics
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*/
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static void
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bpfstats_fill_xbpf(struct xbpf_d *d, struct bpf_d *bd)
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{
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@ -2529,6 +2619,7 @@ bpfstats_fill_xbpf(struct xbpf_d *d, struct bpf_d *bd)
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bzero(d, sizeof(*d));
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BPFD_LOCK_ASSERT(bd);
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d->bd_structsize = sizeof(*d);
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/* XXX: reading should be protected by global lock */
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d->bd_immediate = bd->bd_immediate;
|
||||
d->bd_promisc = bd->bd_promisc;
|
||||
d->bd_hdrcmplt = bd->bd_hdrcmplt;
|
||||
@ -2553,6 +2644,9 @@ bpfstats_fill_xbpf(struct xbpf_d *d, struct bpf_d *bd)
|
||||
d->bd_bufmode = bd->bd_bufmode;
|
||||
}
|
||||
|
||||
/*
|
||||
* Handle `netstat -B' stats request
|
||||
*/
|
||||
static int
|
||||
bpf_stats_sysctl(SYSCTL_HANDLER_ARGS)
|
||||
{
|
||||
|
Loading…
Reference in New Issue
Block a user