When enumerating RFCOMM devices in the rfcomm_dev_list, holding
the rfcomm_dev_lock only guarantees the existence of the enumerated
rfcomm_dev in memory, and not safe access to its state. Testing
the device state (such as RFCOMM_TTY_RELEASED) does not guarantee
the device will remain in that state for the subsequent access
to the rfcomm_dev's fields, nor guarantee that teardown has not
commenced.

Obtain an rfcomm_dev reference for the duration of rfcomm_dev
access.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Tested-By: NAlexander Holler <holler@ahsoftware.de>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

rfcomm_dev_get() can return a rfcomm_dev reference for a
device for which destruction may be commencing. This can happen
on tty destruction, which calls rfcomm_tty_cleanup(), the last
port reference may have been released but RFCOMM_TTY_RELEASED
was not set. The following race is also possible:

CPU 0                            | CPU 1
                                 | rfcomm_release_dev
rfcomm_dev_get                   |   .
  spin_lock                      |   .
    dev  = __rfcomm_dev_get      |   .
    if dev                       |   .
      if test_bit(TTY_RELEASED)  |   .
                                 |   !test_and_set_bit(TTY_RELEASED)
                                 |     tty_port_put   <<<< last reference
      else                       |
        tty_port_get             |

The reference acquire is bogus because destruction will commence
with the release of the last reference.

Ignore the external state change of TTY_RELEASED and instead rely
on the reference acquire itself to determine if the reference is
valid.

Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Tested-By: NAlexander Holler <holler@ahsoftware.de>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

This reverts commit e228b633.

This is the third of a 3-patch revert, together with
Revert "Bluetooth: Remove rfcomm_carrier_raised()" and
Revert "Bluetooth: Always wait for a connection on RFCOMM open()".

Commit 4a2fb3ec,
"Bluetooth: Always wait for a connection on RFCOMM open()" open-codes
blocking on tty open(), rather than using the default behavior
implemented by the tty port.

The reasons for reverting that patch are detailed in that changelog;
this patch restores required functionality for that revert.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Tested-By: NAlexander Holler <holler@ahsoftware.de>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

This reverts commit 4a2fb3ec.

This is the second of a 3-patch revert, together with
Revert "Bluetooth: Remove rfcomm_carrier_raised()" and
Revert "Bluetooth: Move rfcomm_get_device() before rfcomm_dev_activate()".

Before commit cad348a1,
  Bluetooth: Implement .activate, .shutdown and .carrier_raised methods,
tty_port_block_til_ready() was open-coded in rfcomm_tty_install() as
part of the RFCOMM tty open().

Unfortunately, it did not implement non-blocking open nor CLOCAL open,
but rather always blocked for carrier. This is not the expected or
typical behavior for ttys, and prevents several common terminal
programming idioms from working (eg., opening in non-blocking
mode to initialize desired termios settings then re-opening for
connection).

Commit cad348a1,
  Bluetooth: Implement .activate, .shutdown and .carrier_raised methods,
added the necessary tty_port methods to use the default tty_port_open().
However, this triggered two important user-space regressions.

The first regression involves the complicated mechanism for reparenting
the rfcomm tty device to the ACL link device which represents an
open link to a specific bluetooth host. This regression causes ModemManager
to conclude the rfcomm tty device does not front a modem so it makes
no attempt to initialize an attached modem. This regression is
caused by the lack of a device_move() if the dlc is already open (and
not specifically related to the open-coded block_til_ready()).

A more appropriate solution is submitted in
"Bluetooth: Fix unsafe RFCOMM device parenting" and
"Bluetooth: Fix RFCOMM parent device for reused dlc"

The second regression involves "rfcomm bind" and wvdial (a ppp dialer).
rfcomm bind creates a device node for a /dev/rfcomm<n>. wvdial opens
that device in non-blocking mode (because it expects the connection
to have already been established). In addition, subsequent writes
to the rfcomm tty device fail (because the link is not yet connected;
rfcomm connection begins with the actual tty open()).

However, restoring the original behavior (in the patch which
this reverts) was undesirable.

Firstly, the original reporter notes that a trivial userspace
"workaround" already exists: rfcomm connect, which creates the
device node and establishes the expected connection.

Secondly, the failed writes occur because the rfcomm tty driver
does not buffer writes to an unconnected device; this contrasts with
the dozen of other tty drivers (in fact, all of them) that do just
that. The submitted patch "Bluetooth: Don't fail RFCOMM tty writes"
corrects this.

Thirdly, it was a long-standing bug to block on non-blocking open,
which is re-fixed by revert.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Tested-By: NAlexander Holler <holler@ahsoftware.de>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

This reverts commit f86772af.

This is the first of a 3-patch revert, together with
Revert "Bluetooth: Always wait for a connection on RFCOMM open()" and
Revert "Bluetooth: Move rfcomm_get_device() before rfcomm_dev_activate()".

Commit 4a2fb3ec,
"Bluetooth: Always wait for a connection on RFCOMM open()" open-codes
blocking on tty open(), rather than using the default behavior
implemented by the tty port.

The reasons for reverting that patch are detailed in that changelog;
this patch restores required functionality for that revert.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Tested-By: NAlexander Holler <holler@ahsoftware.de>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

Remove the rfcomm_carrier_raised() definition as that function isn't
used anymore.
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

This patch fixes two regressions introduced with the recent rfcomm tty
rework.

The current code uses the carrier_raised() method to wait for the
bluetooth connection when a process opens the tty.

However processes may open the port with the O_NONBLOCK flag or set the
CLOCAL termios flag: in these cases the open() syscall returns
immediately without waiting for the bluetooth connection to
complete.

This behaviour confuses userspace which expects an established bluetooth
connection.

The patch restores the old behaviour by waiting for the connection in
rfcomm_dev_activate() and removes carrier_raised() from the tty_port ops.

As a side effect the new code also fixes the case in which the rfcomm
tty device is created with the flag RFCOMM_REUSE_DLC: the old code
didn't call device_move() and ModemManager skipped the detection
probe. Now device_move() is always called inside rfcomm_dev_activate().
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Reported-by: NAndrey Vihrov <andrey.vihrov@gmail.com>
Reported-by: NBeson Chow <blc+bluez@mail.vanade.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

This is a preparatory patch which moves the rfcomm_get_device()
definition before rfcomm_dev_activate() where it will be used.
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

This patch fixes a userspace regression introduced by the commit
29cd718b.

If the rfcomm device was created with the flag RFCOMM_RELEASE_ONHUP the
user space expects that the tty_port is released as soon as the last
process closes the tty.

The current code attempts to release the port in the function
rfcomm_dev_state_change(). However it won't get a reference to the
relevant tty to send a HUP: at that point the tty is already destroyed
and therefore NULL.

This patch fixes the regression by taking over the tty refcount in the
tty install method(). This way the tty_port is automatically released as
soon as the tty is destroyed.

As a consequence the check for RFCOMM_RELEASE_ONHUP flag in the hangup()
method is now redundant. Instead we have to be careful with the reference
counting in the rfcomm_release_dev() function.
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Reported-by: NAlexander Holler <holler@ahsoftware.de>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

When the dlc is closed, rfcomm_dev_state_change() tries to release the
port in the case it cannot get a reference to the tty. However this is
racy and not even needed.

Infact as Peter Hurley points out:

1. Only consider dlcs that are 'stolen' from a connected socket, ie.
   reused. Allocated dlcs cannot have been closed prior to port
   activate and so for these dlcs a tty reference will always be avail
   in rfcomm_dev_state_change() -- except for the conditions covered by
   #2b below.
2. If a tty was at some point previously created for this rfcomm, then
   either
   (a) the tty reference is still avail, so rfcomm_dev_state_change()
       will perform a hangup. So nothing to do, or,
   (b) the tty reference is no longer avail, and the tty_port will be
       destroyed by the last tty_port_put() in rfcomm_tty_cleanup.
       Again, no action required.
3. Prior to obtaining the dlc lock in rfcomm_dev_add(),
   rfcomm_dev_state_change() will not 'see' a rfcomm_dev so nothing to
   do here.
4. After releasing the dlc lock in rfcomm_dev_add(),
   rfcomm_dev_state_change() will 'see' an incomplete rfcomm_dev if a
   tty reference could not be obtained. Again, the best thing to do here
   is nothing. Any future attempted open() will block on
   rfcomm_dev_carrier_raised(). The unconnected device will exist until
   released by ioctl(RFCOMMRELEASEDEV).

The patch removes the aforementioned code and uses the
tty_port_tty_hangup() helper to hangup the tty.
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

In rfcomm_tty_cleanup we purge the dlc->tx_queue which may contain
socket buffers referencing the tty_port and thus preventing the tty_port
destruction.
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The tty_port can be released in two cases: when we get a HUP in the
functions rfcomm_tty_hangup() and rfcomm_dev_state_change(). Or when the
user releases the device in rfcomm_release_dev().

In these cases we set the flag RFCOMM_TTY_RELEASED so that no other
function can get a reference to the tty_port.
The use of !test_and_set_bit(RFCOMM_TTY_RELEASED) ensures that the
'initial' tty_port reference is only dropped once.

The rfcomm_dev_del function is removed becase it isn't used anymore.
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

Implement .activate, .shutdown and .carrier_raised methods of tty_port
to manage the dlc, moving the code from rfcomm_tty_install() and
rfcomm_tty_cleanup() functions.

At the same time the tty .open()/.close() and .hangup() methods are
changed to use the tty_port helpers that properly call the
aforementioned tty_port methods.
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

Move the tty_struct initialization from rfcomm_tty_open() to
rfcomm_tty_install() and do the same for the cleanup moving the code from
rfcomm_tty_close() to rfcomm_tty_cleanup().

Add also extra error handling in rfcomm_tty_install() because, unlike
.open()/.close(), .cleanup() is not called if .install() fails.
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The current code removes the device from the device list in several
places. Do it only in the destructor instead and in the error path of
rfcomm_add_dev() if the device couldn't be initialized.
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

In net/bluetooth/rfcomm/tty.c the struct tty_struct is used without
taking references. This may lead to a use-after-free of the rfcomm tty.

Fix this by taking references properly, using the tty_port_* helpers
when possible.

The raw assignments of dev->port.tty in rfcomm_tty_open/close are
addressed in the later commit 'rfcomm: Implement .activate, .shutdown
and .carrier_raised methods'.
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

Now, the one where most of tty_port_tty_get gets removed:
tty_flip_buffer_push.

IOW we also closed all the races in drivers not using tty_port_tty_get
at all yet.

Also we move tty_flip_buffer_push declaration from include/linux/tty.h
to include/linux/tty_flip.h to all others while we are changing it
anyway.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

tty_insert_flip_string this time.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Instead of old unsafe batostr function use %pMR print specifier
for printing Bluetooth addresses in sprintf and seq_printf
statements.
Signed-off-by: NAndrei Emeltchenko <andrei.emeltchenko@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

Instead of old unsafe batostr function use %pMR print specifier
for printing Bluetooth addresses in debug and error statements.
Signed-off-by: NAndrei Emeltchenko <andrei.emeltchenko@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The RFCOMM code fails to initialize the two padding bytes of struct
rfcomm_dev_list_req inserted for alignment before copying it to
userland. Additionally there are two padding bytes in each instance of
struct rfcomm_dev_info. The ioctl() that for disclosures two bytes plus
dev_num times two bytes uninitialized kernel heap memory.

Allocate the memory using kzalloc() to fix this issue.
Signed-off-by: NMathias Krause <minipli@googlemail.com>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently we have no way to assign tty->port while performing tty
installation. There are two ways to provide the link tty_struct =>
tty_port. Either by calling tty_port_install from tty->ops->install or
tty_port_register_device called instead of tty_register_device when
the device is being set up after connected.

In this patch we modify most of the drivers to do the latter. When the
drivers use tty_register_device and we have tty_port already, we
switch to tty_port_register_device. So we have the tty_struct =>
tty_port link for free for those.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Acked-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The termios and other changes mean the other protections needed on the driver
tty arrays should be adequate. Turn it all back on.

This contains pieces folded in from the fixes made to the original patches

| From: Geert Uytterhoeven <geert@linux-m68k.org>	(fix m68k)
| From: Paul Gortmaker <paul.gortmaker@windriver.com>	(fix cris)
| From: Jiri Kosina <jkosina@suze.cz>			(lockdep)
| From: Eric Dumazet <eric.dumazet@gmail.com>		(lockdep)
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This will let us sort out a whole pile of tty related races. The
alternative would be to keep points and refcount the termios objects.
However
1. They are tiny anyway
2. Many devices don't use the stored copies
3. We can remove a pty special case
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

I sent GregKH this after the pre-requisites. He dropped the pre-requesites
for good reason and unfortunately then applied this patch. Without this
reverted you get random kernel memory corruption which will make bisecting
anything between it and the properly applied patches a complete sod.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The termios and other changes mean the other protections needed on the driver
tty arrays should be adequate. Turn it all back on.

This contains pieces folded in from the fixes made to the original patches

| From: Geert Uytterhoeven <geert@linux-m68k.org>	(fix m68k)
| From: Paul Gortmaker <paul.gortmaker@windriver.com>	(fix cris)
| From: Jiri Kosina <jkosina@suze.cz>			(lockdep)
| From: Eric Dumazet <eric.dumazet@gmail.com>		(lockdep)
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Most of the include were unnecessary or already included by some other
header.
Replace module.h by export.h where possible.
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

Only obvious cases were left as inline, mostly oneline functions.
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

This reverts the tty layer change to use per-tty locking, because it's
not correct yet, and fixing it will require some more deep surgery.

The main revert is d29f3ef3 ("tty_lock: Localise the lock"), but
there are several smaller commits that built upon it, they also get
reverted here. The list of reverted commits is:

  fde86d31 - tty: add lockdep annotations
  8f6576ad - tty: fix ldisc lock inversion trace
  d3ca8b64 - pty: Fix lock inversion
  b1d679af - tty: drop the pty lock during hangup
  abcefe5f - tty/amiserial: Add missing argument for tty_unlock()
  fd11b42e - cris: fix missing tty arg in wait_event_interruptible_tty call
  d29f3ef3 - tty_lock: Localise the lock

The revert had a trivial conflict in the 68360serial.c staging driver
that got removed in the meantime.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In each remaining case the tty_lock is associated with a specific tty. This
means we can now lock on a per tty basis. We do need tty_lock_pair() for
the pty case. Uglier but still a step in the right direction.

[fixed up calls in 3 missing drivers - gregkh]
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This means converting an atomic counter to a counter protected by
lock. This is the first step needed to convert the rest of the code to
the tty_port helpers.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

tty_wakeup is safe to be called from all contexts. No need to schedule
a work for that. Let us call it directly like in other drivers.

This allows us to kill another member of rfcomm_dev structure.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Switch the refcounting from manual atomic plays with refcounter to the
one offered by tty_port.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

And use tty from there.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

All num, magic and owner are set by alloc_tty_driver. No need to
re-set them on each allocation site.

pti driver sets something different to what it passes to
alloc_tty_driver. It is not a bug, since we don't use the lines
parameter in any way. Anyway this is fixed, and now we do the right
thing.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Acked-by: NTilman Schmidt <tilman@imap.cc>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

+ src/net/bluetooth/rfcomm/tty.c: warning: 'p' is used uninitialized in this
       function:  => 218
+ src/net/bluetooth/rfcomm/tty.c: warning: 'p' may be used uninitialized in
       this function:  => 218
Signed-off-by: NLuiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: NGustavo F. Padovan <padovan@profusion.mobi>

We now run in process context, no need to disable interrupts.
Calls from the tty layer also run in process context.

rw_lock was converted to spinlock, we have more writers than readers in
this case.
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo F. Padovan <padovan@profusion.mobi>

When all items in the list have the same type there is no much of a point
to use list_for_each except if you want to use the list pointer itself.
Signed-off-by: NLuiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: NGustavo F. Padovan <padovan@profusion.mobi>

Remove old tasklets and replace by workqueue. To avoid reentrancy (which
tasklets always avoid) we use the system_nrt_wq.
Signed-off-by: NDavid Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: NGustavo F. Padovan <padovan@profusion.mobi>

Forward error codes from tty core to the rfcomm_init caller instead of using
generic -1 errors.
Signed-off-by: NDavid Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: NGustavo F. Padovan <padovan@profusion.mobi>