Since l2cap_send_ack can trigger extra actions like sending iframes,
don't call it.  Just send an RR or RNR frame if an ack needs sending.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

Different states have different actions for retransmit and monitor
timeouts, so remove the logic for those actions from the timer handlers.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The ERTM specification requires the retransmit timer to be cancelled
when the monitor timer is set.  The retransmit timer cannot be set
again while the monitor timer is pending.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

struct l2cap_ctrl is now used, and the sframe is now sent directly
rather than depending on a separate call.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

REJ frames are sent by the remote device to request that all frames
after a given sequence number be retransmitted.  These are also an
implicit indication that the remote device is not in a busy state and
can receive new iframes.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

When a remote device sends an SREJ, retransmit the frame with the
corresponding sequence number (subject to special cases with poll and
final flags).  An SREJ is also an implicit indication the the remote
device is not in a busy state.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

As retransmitted packets arrive, attempt to reassemble SDUs.  If all
requested retransmissions have been received, acknowledge them and
transition back to the RECV state.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The ERTM specification lays out three scenarios for sending SREJ
frames to request retransmission of specific frames.  l2cap_send_srej
requests all frames up to a given txseq that are not already queued
for reassembly.  l2cap_send_srej_tail only requests the most recent
missing frame.  l2cap_send_srej_list resends SREJ frames for data that
was requested for resend but never received.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This adds l2cap_ertm_resend to retransmit frames based on the sequence
numbers in chan->retrans_list.  If the retransmit limit is reached for
any individual frame is reached, the connection is dropped.  skbs that
are cloned already are copied to avoid modifying shared data (this is
uncommon).  To retransmit all frames, l2cap_retransmit_all now builds
a list of all unacked sequence numbers and then calls
l2cap_ertm_resend.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This adds a top-level state machine with handlers for two receive
states defined in the ERTM spec, RECV and SREJ_SENT.  The reqseq value
of the incoming frame is also validated at the top level and a
disconnection is forced if it is invalid.  The actions for the RECV
and SREJ_SENT states are implemented according to the state tables in
the ERTM specification.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This action now exactly matches what is defined in the ERTM
specification, including clearing the remote busy flag and setting the
retransmit timer rather than retransmitting frames directly.  The spec
does not retransmit frames as part of this action, since
retransmission is only triggered by REJ, SREJ, or an RR with the final
bit set.  struct l2cap_ctrl is also used to set up header values.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This lets the transmit state machine handle local busy state changes,
since different actions are taken in the different transmit states.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The function now encapsulates more of the logic to either immediately
send an ack if the transmit window is over 75% full, or wait for the
ack timer to expire if the transmit window is not full enough.  It is
also able to push out waiting iframes that can carry an
acknowledgement.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This deletes the receive code that had handlers for each frame type at
the top level, and then had logic to determine the receive state
within each handler.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

Streaming mode reception is fairly simple, with in-sequence frames
being reassembled as they arrive.  Out-of-sequence frames are dropped,
and also clear any partially-assembled SDUs that may exist.

The packet classifier determines if the txseq value of the incoming
packet is expected, invalid (resulting in a disconnection), invalid
(ignorable), duplicate, or having to do with an SREJ request that was
previously sent.  The rules for each classification are defined in the
ERTM specification, and consolidating these rules in one place helps
clarify the receive state machine.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

Creates a new l2cap_data_rcv function that combines previous code from
l2cap_ertm_data_rcv and l2cap_data_channel.  This reduces duplicate
code for streaming mode, and sets up a framework for the ERTM receive
state machine.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The new implementation uses struct l2cap_ctrl to set up the sframe
fields, and also reduces duplicate acks by canceling the ack timer
whenever an RR or RNR frame is sent.  sframe PDU generation is also
split in to a separate function to separate it from the logic related
to the connection state and sframe type.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The new implementation is aware of the new transmit state machine, and
uses struct l2cap_ctrl to compose ERTM headers.  It also has improved
error handling for allocation failures, and does not send the packet
until after all skb and channel data structures are updated.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This new implementation uses struct l2cap_ctrl to compose the
streaming mode headers.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This implements a top-level transmit state machine with handlers for
the two ERTM states defined in the specification: XMIT and WAIT_F.

The state machine accepts an event and, optionally, a list of skbs to
transmit.  In addition to data transmission, the local busy state can
be modified, acks are processed, and monitor and retransmit timeouts
are handled.  This mirrors the structure of the state tables in the
spec.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This is to allow for ERTM state machine replacement in the patches
that follow.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This fixes a regression from commit
2ead70b8 that is present in all
kernels starting at v3.0.

When L2CAP information was moved to struct l2cap_chan, a check was
added to l2cap_chan_del to avoid certain cleanup operations when ERTM
or streaming mode had not yet been initialized.  The logic in the
check did not take in to account that chan->conf_state is set to 0 in
l2cap_chan_ready, so l2cap_chan_del failed to cancel timers and leaked
memory any time the ERTM queues or lists were not empty.

This change makes sure that l2cap_chan_del only returns early if
ERTM initialization was not performed.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

If the ERTM SREJ list is properly allocated but the retransmit list
allocation fails, the SREJ list must be freed before returning from
l2cap_ertm_init.  l2cap_chan_del will not clean up the SREJ list
if l2cap_ertm_init returns a failure code.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

defer_setup and suspended are now flags into bt_sk().
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

As the comment for l2cap_get_chan_by_scid indicated, the function used
to return a locked socket.  The lock for the socket was acquired while
the channel list was also locked.

When locking was moved over to the l2cap_chan structure, the channel
lock was no longer acquired with the channel list still locked.  This
made it possible for the l2cap_chan to be deleted after
conn->chan_lock was released but before l2cap_chan_lock was called.
Making the call to l2cap_chan_lock before releasing conn->chan_lock
makes it impossible for the l2cap_chan to be deleted at the wrong
time.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Reviewed-by: NUlisses Furquim <ulisses@profusion.mobi>
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>

The L2CAP MTU for incoming data is verified differently depending on
the L2CAP mode, so the check is best performed in a mode-specific
context.  Checking the incoming MTU before HCI fragment reassembly is
a layer violation and assumes all bytes after the standard L2CAP
header are L2CAP data.

This approach causes issues with unsegmented ERTM or streaming mode
frames, where there are additional enhanced or extended headers before
the data payload and possible FCS bytes after the data payload.  A
valid frame could be as many as 10 bytes larger than the MTU.

Removing this code is the best fix, because the MTU is checked later
on for all L2CAP data frames (connectionless, basic, ERTM, and
streaming).  This also gets rid of outdated locking (socket instead of
l2cap_chan) and an extra lookup of the channel ID.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Reviewed-by: NUlisses Furquim <ulisses@profusion.mobi>
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>

Removes one indentation level.
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

When we add a fragment to a skb, len and data_len fields need to be
updated.
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

If alloc() fails we let the frags linked list with garbage value (the
err ptr value) in its last element.
Reported-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

Commit 105bdf9e introduced a
regression in L2CAP streaming mode due to rearranged initialization
code that is shared between ERTM and streaming mode.  This change
makes sure the transmit queue is initialized in both modes.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Acked-by: NAndrei Emeltchenko <andrei.emeltchenko@intel.com>
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>

Commit 94122bbe introduced a problem
where tx_send_head was not set to point to the first skb in the ERTM
transmit queue, which stalled data transmission.  This change sets
that pointer when transmission is not already in progress.
Reported-by: NAndrei Emeltchenko <andrei.emeltchenko@intel.com>
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>

It fixes L2CAP socket based security level elevation during a
connection. The HID profile needs this (for keyboards) and it is the only
way to achieve the security level elevation when using the management
interface to talk to the kernel (hence the management enabling patch
being the one that exposes this issue).

It enables the userspace a security level change when the socket is
already connected and create a way to notify the socket the result of the
request. At the moment of the request the socket is made non writable, if
the request fails the connections closes, otherwise the socket is made
writable again, POLL_OUT is emmited.
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Use more common code for ERTM and streaming mode segmentation and
transmission, and begin using skb control block data for delaying
extended or enhanced header generation until just before the packet is
transmitted.  This code is also better suited for resegmentation,
which is needed when L2CAP links are reconfigured after an AMP channel
move.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Reviewed-by: NUlisses Furquim <ulisses@profusion.mobi>
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>

Remove magic number unneeded calculation since
hlen = L2CAP_HDR_SIZE + L2CAP_PSMLEN_SIZE
Signed-off-by: NAndrei Emeltchenko <andrei.emeltchenko@intel.com>
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>

hlen has a fixed size of L2CAP_HDR_SIZE, use this instead.
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

hlen - L2CAP_HDR_SIZE = 0, so we don't need to add them in the
calculation.
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

Adding Code Aurora Forum copyright information due to significant
additions of code.
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>

L2CAP sockets contain a pointer to l2cap_chan that needs to be
reference counted in order to prevent a possible dangling pointer when
the channel is freed.

There were a few other cases where an l2cap_chan pointer on the stack
was dereferenced after a call to l2cap_chan_del. Those pointers are
also now reference counted.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>

l2cap_get_chan_by_ident was not used, but didn't generate a compiler
warning because it was an inline function.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>

Structure members used by ERTM or streaming mode need to be
initialized when an ERTM or streaming mode link is configured.  Some
duplicate code is also eliminated by moving in to the ERTM init
function.
Signed-off-by: NMat Martineau <mathewm@codeaurora.org>
Signed-off-by: NGustavo Padovan <gustavo@padovan.org>