linux.git/net/nfc, branch v4.11

net: Work around lockdep limitation in sockets that use sockets

2017-03-10T02:23:27+00:00

Lockdep issues a circular dependency warning when AFS issues an operation
through AF_RXRPC from a context in which the VFS/VM holds the mmap_sem.

The theory lockdep comes up with is as follows:

 (1) If the pagefault handler decides it needs to read pages from AFS, it
     calls AFS with mmap_sem held and AFS begins an AF_RXRPC call, but
     creating a call requires the socket lock:

	mmap_sem must be taken before sk_lock-AF_RXRPC

 (2) afs_open_socket() opens an AF_RXRPC socket and binds it.  rxrpc_bind()
     binds the underlying UDP socket whilst holding its socket lock.
     inet_bind() takes its own socket lock:

	sk_lock-AF_RXRPC must be taken before sk_lock-AF_INET

 (3) Reading from a TCP socket into a userspace buffer might cause a fault
     and thus cause the kernel to take the mmap_sem, but the TCP socket is
     locked whilst doing this:

	sk_lock-AF_INET must be taken before mmap_sem

However, lockdep's theory is wrong in this instance because it deals only
with lock classes and not individual locks.  The AF_INET lock in (2) isn't
really equivalent to the AF_INET lock in (3) as the former deals with a
socket entirely internal to the kernel that never sees userspace.  This is
a limitation in the design of lockdep.

Fix the general case by:

 (1) Double up all the locking keys used in sockets so that one set are
     used if the socket is created by userspace and the other set is used
     if the socket is created by the kernel.

 (2) Store the kern parameter passed to sk_alloc() in a variable in the
     sock struct (sk_kern_sock).  This informs sock_lock_init(),
     sock_init_data() and sk_clone_lock() as to the lock keys to be used.

     Note that the child created by sk_clone_lock() inherits the parent's
     kern setting.

 (3) Add a 'kern' parameter to ->accept() that is analogous to the one
     passed in to ->create() that distinguishes whether kernel_accept() or
     sys_accept4() was the caller and can be passed to sk_alloc().

     Note that a lot of accept functions merely dequeue an already
     allocated socket.  I haven't touched these as the new socket already
     exists before we get the parameter.

     Note also that there are a couple of places where I've made the accepted
     socket unconditionally kernel-based:

	irda_accept()
	rds_rcp_accept_one()
	tcp_accept_from_sock()

     because they follow a sock_create_kern() and accept off of that.

Whilst creating this, I noticed that lustre and ocfs don't create sockets
through sock_create_kern() and thus they aren't marked as for-kernel,
though they appear to be internal.  I wonder if these should do that so
that they use the new set of lock keys.

Signed-off-by: David Howells 
Signed-off-by: David S. Miller

sched/headers: Prepare to move signal wakeup & sigpending methods from into

2017-03-02T07:42:32+00:00

Fix up affected files that include this signal functionality via sched.h.

Acked-by: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

genetlink: mark families as __ro_after_init

2016-10-27T20:16:09+00:00

Now genl_register_family() is the only thing (other than the
users themselves, perhaps, but I didn't find any doing that)
writing to the family struct.

In all families that I found, genl_register_family() is only
called from __init functions (some indirectly, in which case
I've add __init annotations to clarifly things), so all can
actually be marked __ro_after_init.

This protects the data structure from accidental corruption.

Signed-off-by: Johannes Berg 
Signed-off-by: David S. Miller

genetlink: statically initialize families

2016-10-27T20:16:09+00:00

Instead of providing macros/inline functions to initialize
the families, make all users initialize them statically and
get rid of the macros.

This reduces the kernel code size by about 1.6k on x86-64
(with allyesconfig).

Signed-off-by: Johannes Berg 
Signed-off-by: David S. Miller

genetlink: no longer support using static family IDs

2016-10-27T20:16:09+00:00

Static family IDs have never really been used, the only
use case was the workaround I introduced for those users
that assumed their family ID was also their multicast
group ID.

Additionally, because static family IDs would never be
reserved by the generic netlink code, using a relatively
low ID would only work for built-in families that can be
registered immediately after generic netlink is started,
which is basically only the control family (apart from
the workaround code, which I also had to add code for so
it would reserve those IDs)

Thus, anything other than GENL_ID_GENERATE is flawed and
luckily not used except in the cases I mentioned. Move
those workarounds into a few lines of code, and then get
rid of GENL_ID_GENERATE entirely, making it more robust.

Signed-off-by: Johannes Berg 
Signed-off-by: David S. Miller

genetlink: introduce and use genl_family_attrbuf()

2016-10-27T20:16:08+00:00

This helper function allows family implementations to access
their family's attrbuf. This gets rid of the attrbuf usage
in families, and also adds locking validation, since it's not
valid to use the attrbuf with parallel_ops or outside of the
dumpit callback.

Signed-off-by: Johannes Berg 
Signed-off-by: David S. Miller

NFC: digital: Fix RTOX supervisor PDU handling

2016-07-11T00:02:03+00:00

When the target needs more time to process the received PDU, it sends
Response Timeout Extension (RTOX) PDU.

When the initiator receives a RTOX PDU, it must reply with a RTOX PDU
and extends the current rwt value with the formula:
 rwt_int = rwt * rtox

This patch takes care of the rtox value passed by the target in the RTOX
PDU and extends the timeout for the next response accordingly.

Signed-off-by: Thierry Escande 
Signed-off-by: Samuel Ortiz

NFC: digital: Add support for NFC DEP Response Waiting Time

2016-07-11T00:01:14+00:00

When sending an ATR_REQ, the initiator must wait for the ATR_RES at
least 'RWT(nfcdep,activation) + dRWT(nfcdep)' and no more than
'RWT(nfcdep,activation) + dRWT(nfcdep) + dT(nfcdep,initiator)'. This
gives a timeout value between 1237 ms and 1337 ms. This patch defines
DIGITAL_ATR_RES_RWT to 1337 used for the timeout value of ATR_REQ
command.

For other DEP PDUs, the initiator must wait between 'RWT + dRWT(nfcdep)'
and 'RWT + dRWT(nfcdep) + dT(nfcdep,initiator)' where RWT is given by
the following formula: '(256 * 16 / f(c)) * 2^wt' where wt is the value
of the TO field in the ATR_RES response and is in the range between 0
and 14. This patch declares a mapping table for wt values and gives RWT
max values between 100 ms and 5049 ms.

This patch also defines DIGITAL_ATR_RES_TO_WT, the maximum wt value in
target mode, to 8.

Signed-off-by: Thierry Escande 
Signed-off-by: Samuel Ortiz

NFC: digital: Free supervisor PDUs

2016-07-11T00:00:26+00:00

This patch frees the RTOX resp sk_buff in initiator mode. It also makes
use of the free_resp exit point for ATN supervisor PDUs in both
initiator and target mode.

Signed-off-by: Thierry Escande 
Signed-off-by: Samuel Ortiz

NFC: digital: Rework ACK PDU handling in initiator mode

2016-07-10T23:59:37+00:00

With this patch, ACK PDU sk_buffs are now freed and code has been
refactored for better errors handling.

Signed-off-by: Thierry Escande 
Signed-off-by: Samuel Ortiz