linux-stable.git/net/tls, branch v5.3.4

net: tls, fix sk_write_space NULL write when tx disabled

2019-08-15T19:40:15+00:00

The ctx->sk_write_space pointer is only set when TLS tx mode is enabled.
When running without TX mode its a null pointer but we still set the
sk sk_write_space pointer on close().

Fix the close path to only overwrite sk->sk_write_space when the current
pointer is to the tls_write_space function indicating the tls module should
clean it up properly as well.

Reported-by: Hillf Danton 
Cc: Ying Xue 
Cc: Andrey Konovalov 
Fixes: 57c722e932cfb ("net/tls: swap sk_write_space on close")
Signed-off-by: John Fastabend 
Reviewed-by: Jakub Kicinski 
Signed-off-by: David S. Miller

net/tls: swap sk_write_space on close

2019-08-10T02:55:22+00:00

Now that we swap the original proto and clear the ULP pointer
on close we have to make sure no callback will try to access
the freed state. sk_write_space is not part of sk_prot, remember
to swap it.

Reported-by: syzbot+dcdc9deefaec44785f32@syzkaller.appspotmail.com
Fixes: 95fa145479fb ("bpf: sockmap/tls, close can race with map free")
Signed-off-by: Jakub Kicinski 
Signed-off-by: David S. Miller

net/tls: prevent skb_orphan() from leaking TLS plain text with offload

2019-08-09T05:39:35+00:00

sk_validate_xmit_skb() and drivers depend on the sk member of
struct sk_buff to identify segments requiring encryption.
Any operation which removes or does not preserve the original TLS
socket such as skb_orphan() or skb_clone() will cause clear text
leaks.

Make the TCP socket underlying an offloaded TLS connection
mark all skbs as decrypted, if TLS TX is in offload mode.
Then in sk_validate_xmit_skb() catch skbs which have no socket
(or a socket with no validation) and decrypted flag set.

Note that CONFIG_SOCK_VALIDATE_XMIT, CONFIG_TLS_DEVICE and
sk->sk_validate_xmit_skb are slightly interchangeable right now,
they all imply TLS offload. The new checks are guarded by
CONFIG_TLS_DEVICE because that's the option guarding the
sk_buff->decrypted member.

Second, smaller issue with orphaning is that it breaks
the guarantee that packets will be delivered to device
queues in-order. All TLS offload drivers depend on that
scheduling property. This means skb_orphan_partial()'s
trick of preserving partial socket references will cause
issues in the drivers. We need a full orphan, and as a
result netem delay/throttling will cause all TLS offload
skbs to be dropped.

Reusing the sk_buff->decrypted flag also protects from
leaking clear text when incoming, decrypted skb is redirected
(e.g. by TC).

See commit 0608c69c9a80 ("bpf: sk_msg, sock{map|hash} redirect
through ULP") for justification why the internal flag is safe.
The only location which could leak the flag in is tcp_bpf_sendmsg(),
which is taken care of by clearing the previously unused bit.

v2:
 - remove superfluous decrypted mark copy (Willem);
 - remove the stale doc entry (Boris);
 - rely entirely on EOR marking to prevent coalescing (Boris);
 - use an internal sendpages flag instead of marking the socket
   (Boris).
v3 (Willem):
 - reorganize the can_skb_orphan_partial() condition;
 - fix the flag leak-in through tcp_bpf_sendmsg.

Signed-off-by: Jakub Kicinski 
Acked-by: Willem de Bruijn 
Reviewed-by: Boris Pismenny 
Signed-off-by: David S. Miller

net/tls: partially revert fix transition through disconnect with close

2019-08-05T20:15:30+00:00

Looks like we were slightly overzealous with the shutdown()
cleanup. Even though the sock->sk_state can reach CLOSED again,
socket->state will not got back to SS_UNCONNECTED once
connections is ESTABLISHED. Meaning we will see EISCONN if
we try to reconnect, and EINVAL if we try to listen.

Only listen sockets can be shutdown() and reused, but since
ESTABLISHED sockets can never be re-connected() or used for
listen() we don't need to try to clean up the ULP state early.

Fixes: 32857cf57f92 ("net/tls: fix transition through disconnect with close")
Signed-off-by: Jakub Kicinski 
Signed-off-by: David S. Miller

bpf: sockmap/tls, close can race with map free

2019-07-22T14:04:17+00:00

When a map free is called and in parallel a socket is closed we
have two paths that can potentially reset the socket prot ops, the
bpf close() path and the map free path. This creates a problem
with which prot ops should be used from the socket closed side.

If the map_free side completes first then we want to call the
original lowest level ops. However, if the tls path runs first
we want to call the sockmap ops. Additionally there was no locking
around prot updates in TLS code paths so the prot ops could
be changed multiple times once from TLS path and again from sockmap
side potentially leaving ops pointed at either TLS or sockmap
when psock and/or tls context have already been destroyed.

To fix this race first only update ops inside callback lock
so that TLS, sockmap and lowest level all agree on prot state.
Second and a ULP callback update() so that lower layers can
inform the upper layer when they are being removed allowing the
upper layer to reset prot ops.

This gets us close to allowing sockmap and tls to be stacked
in arbitrary order but will save that patch for *next trees.

v4:
- make sure we don't free things for device;
- remove the checks which swap the callbacks back
only if TLS is at the top.

Reported-by: syzbot+06537213db7ba2745c4a@syzkaller.appspotmail.com
Fixes: 02c558b2d5d6 ("bpf: sockmap, support for msg_peek in sk_msg with redirect ingress")
Signed-off-by: John Fastabend
Signed-off-by: Jakub Kicinski
Reviewed-by: Dirk van der Merwe
Signed-off-by: Daniel Borkmann

net/tls: fix transition through disconnect with close

2019-07-22T14:04:17+00:00

It is possible (via shutdown()) for TCP socks to go through TCP_CLOSE
state via tcp_disconnect() without actually calling tcp_close which
would then call the tls close callback. Because of this a user could
disconnect a socket then put it in a LISTEN state which would break
our assumptions about sockets always being ESTABLISHED state.

More directly because close() can call unhash() and unhash is
implemented by sockmap if a sockmap socket has TLS enabled we can
incorrectly destroy the psock from unhash() and then call its close
handler again. But because the psock (sockmap socket representation)
is already destroyed we call close handler in sk->prot. However,
in some cases (TLS BASE/BASE case) this will still point at the
sockmap close handler resulting in a circular call and crash reported
by syzbot.

To fix both above issues implement the unhash() routine for TLS.

v4:
 - add note about tls offload still needing the fix;
 - move sk_proto to the cold cache line;
 - split TX context free into "release" and "free",
   otherwise the GC work itself is in already freed
   memory;
 - more TX before RX for consistency;
 - reuse tls_ctx_free();
 - schedule the GC work after we're done with context
   to avoid UAF;
 - don't set the unhash in all modes, all modes "inherit"
   TLS_BASE's callbacks anyway;
 - disable the unhash hook for TLS_HW.

Fixes: 3c4d7559159bf ("tls: kernel TLS support")
Reported-by: Eric Dumazet 
Signed-off-by: John Fastabend 
Signed-off-by: Jakub Kicinski 
Signed-off-by: Daniel Borkmann

net/tls: remove sock unlock/lock around strp_done()

2019-07-22T14:04:16+00:00

The tls close() callback currently drops the sock lock to call
strp_done(). Split up the RX cleanup into stopping the strparser
and releasing most resources, syncing strparser and finally
freeing the context.

To avoid the need for a strp_done() call on the cleanup path
of device offload make sure we don't arm the strparser until
we are sure init will be successful.

Signed-off-by: John Fastabend 
Signed-off-by: Jakub Kicinski 
Reviewed-by: Dirk van der Merwe 
Signed-off-by: Daniel Borkmann

net/tls: remove close callback sock unlock/lock around TX work flush

2019-07-22T14:04:16+00:00

The tls close() callback currently drops the sock lock, makes a
cancel_delayed_work_sync() call, and then relocks the sock.

By restructuring the code we can avoid droping lock and then
reclaiming it. To simplify this we do the following,

 tls_sk_proto_close
 set_bit(CLOSING)
 set_bit(SCHEDULE)
 cancel_delay_work_sync() <- cancel workqueue
 lock_sock(sk)
 ...
 release_sock(sk)
 strp_done()

Setting the CLOSING bit prevents the SCHEDULE bit from being
cleared by any workqueue items e.g. if one happens to be
scheduled and run between when we set SCHEDULE bit and cancel
work. Then because SCHEDULE bit is set now no new work will
be scheduled.

Tested with net selftests and bpf selftests.

Signed-off-by: John Fastabend 
Signed-off-by: Jakub Kicinski 
Reviewed-by: Dirk van der Merwe 
Signed-off-by: Daniel Borkmann

net/tls: don't call tls_sk_proto_close for hw record offload

2019-07-22T14:04:16+00:00

The deprecated TOE offload doesn't actually do anything in
tls_sk_proto_close() - all TLS code is skipped and context
not freed. Remove the callback to make it easier to refactor
tls_sk_proto_close().

Signed-off-by: Jakub Kicinski 
Reviewed-by: Dirk van der Merwe 
Signed-off-by: Daniel Borkmann

net/tls: don't arm strparser immediately in tls_set_sw_offload()

2019-07-22T14:04:16+00:00

In tls_set_device_offload_rx() we prepare the software context
for RX fallback and proceed to add the connection to the device.
Unfortunately, software context prep includes arming strparser
so in case of a later error we have to release the socket lock
to call strp_done().

In preparation for not releasing the socket lock half way through
callbacks move arming strparser into a separate function.
Following patches will make use of that.

Signed-off-by: Jakub Kicinski 
Reviewed-by: Dirk van der Merwe 
Signed-off-by: Daniel Borkmann