net: nfc: Fix use-after-free caused by nfc_llcp_find_local

This commit fixes several use-after-free that caused by function
nfc_llcp_find_local(). For example, one UAF can happen when below buggy
time window occurs.

// nfc_genl_llc_get_params | // nfc_unregister_device
|
dev = nfc_get_device(idx); | device_lock(...)
if (!dev) | dev->shutting_down = true;
return -ENODEV; | device_unlock(...);
|
device_lock(...); | // nfc_llcp_unregister_device
| nfc_llcp_find_local()
nfc_llcp_find_local(...); |
| local_cleanup()
if (!local) { |
rc = -ENODEV; | // nfc_llcp_local_put
goto exit; | kref_put(.., local_release)
} |
| // local_release
| list_del(&local->list)
// nfc_genl_send_params | kfree()
local->dev->idx !!!UAF!!! |
|

and the crash trace for the one of the discussed UAF like:

BUG: KASAN: slab-use-after-free in nfc_genl_llc_get_params+0x72f/0x780 net/nfc/netlink.c:1045
Read of size 8 at addr ffff888105b0e410 by task 20114

Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x72/0xa0 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:319 [inline]
print_report+0xcc/0x620 mm/kasan/report.c:430
kasan_report+0xb2/0xe0 mm/kasan/report.c:536
nfc_genl_send_params net/nfc/netlink.c:999 [inline]
nfc_genl_llc_get_params+0x72f/0x780 net/nfc/netlink.c:1045
genl_family_rcv_msg_doit.isra.0+0x1ee/0x2e0 net/netlink/genetlink.c:968
genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline]
genl_rcv_msg+0x503/0x7d0 net/netlink/genetlink.c:1065
netlink_rcv_skb+0x161/0x430 net/netlink/af_netlink.c:2548
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1076
netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
netlink_unicast+0x644/0x900 net/netlink/af_netlink.c:1365
netlink_sendmsg+0x934/0xe70 net/netlink/af_netlink.c:1913
sock_sendmsg_nosec net/socket.c:724 [inline]
sock_sendmsg+0x1b6/0x200 net/socket.c:747
____sys_sendmsg+0x6e9/0x890 net/socket.c:2501
___sys_sendmsg+0x110/0x1b0 net/socket.c:2555
__sys_sendmsg+0xf7/0x1d0 net/socket.c:2584
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3f/0x90 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x72/0xdc
RIP: 0033:0x7f34640a2389
RSP: 002b:00007f3463415168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f34641c1f80 RCX: 00007f34640a2389
RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000006
RBP: 00007f34640ed493 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe38449ecf R14: 00007f3463415300 R15: 0000000000022000
</TASK>

Allocated by task 20116:
kasan_save_stack+0x22/0x50 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0x7f/0x90 mm/kasan/common.c:383
kmalloc include/linux/slab.h:580 [inline]
kzalloc include/linux/slab.h:720 [inline]
nfc_llcp_register_device+0x49/0xa40 net/nfc/llcp_core.c:1567
nfc_register_device+0x61/0x260 net/nfc/core.c:1124
nci_register_device+0x776/0xb20 net/nfc/nci/core.c:1257
virtual_ncidev_open+0x147/0x230 drivers/nfc/virtual_ncidev.c:148
misc_open+0x379/0x4a0 drivers/char/misc.c:165
chrdev_open+0x26c/0x780 fs/char_dev.c:414
do_dentry_open+0x6c4/0x12a0 fs/open.c:920
do_open fs/namei.c:3560 [inline]
path_openat+0x24fe/0x37e0 fs/namei.c:3715
do_filp_open+0x1ba/0x410 fs/namei.c:3742
do_sys_openat2+0x171/0x4c0 fs/open.c:1356
do_sys_open fs/open.c:1372 [inline]
__do_sys_openat fs/open.c:1388 [inline]
__se_sys_openat fs/open.c:1383 [inline]
__x64_sys_openat+0x143/0x200 fs/open.c:1383
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3f/0x90 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x72/0xdc

Freed by task 20115:
kasan_save_stack+0x22/0x50 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:521
____kasan_slab_free mm/kasan/common.c:236 [inline]
____kasan_slab_free mm/kasan/common.c:200 [inline]
__kasan_slab_free+0x10a/0x190 mm/kasan/common.c:244
kasan_slab_free include/linux/kasan.h:162 [inline]
slab_free_hook mm/slub.c:1781 [inline]
slab_free_freelist_hook mm/slub.c:1807 [inline]
slab_free mm/slub.c:3787 [inline]
__kmem_cache_free+0x7a/0x190 mm/slub.c:3800
local_release net/nfc/llcp_core.c:174 [inline]
kref_put include/linux/kref.h:65 [inline]
nfc_llcp_local_put net/nfc/llcp_core.c:182 [inline]
nfc_llcp_local_put net/nfc/llcp_core.c:177 [inline]
nfc_llcp_unregister_device+0x206/0x290 net/nfc/llcp_core.c:1620
nfc_unregister_device+0x160/0x1d0 net/nfc/core.c:1179
virtual_ncidev_close+0x52/0xa0 drivers/nfc/virtual_ncidev.c:163
__fput+0x252/0xa20 fs/file_table.c:321
task_work_run+0x174/0x270 kernel/task_work.c:179
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
exit_to_user_mode_prepare+0x108/0x110 kernel/entry/common.c:204
__syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
syscall_exit_to_user_mode+0x21/0x50 kernel/entry/common.c:297
do_syscall_64+0x4c/0x90 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x72/0xdc

Last potentially related work creation:
kasan_save_stack+0x22/0x50 mm/kasan/common.c:45
__kasan_record_aux_stack+0x95/0xb0 mm/kasan/generic.c:491
kvfree_call_rcu+0x29/0xa80 kernel/rcu/tree.c:3328
drop_sysctl_table+0x3be/0x4e0 fs/proc/proc_sysctl.c:1735
unregister_sysctl_table.part.0+0x9c/0x190 fs/proc/proc_sysctl.c:1773
unregister_sysctl_table+0x24/0x30 fs/proc/proc_sysctl.c:1753
neigh_sysctl_unregister+0x5f/0x80 net/core/neighbour.c:3895
addrconf_notify+0x140/0x17b0 net/ipv6/addrconf.c:3684
notifier_call_chain+0xbe/0x210 kernel/notifier.c:87
call_netdevice_notifiers_info+0xb5/0x150 net/core/dev.c:1937
call_netdevice_notifiers_extack net/core/dev.c:1975 [inline]
call_netdevice_notifiers net/core/dev.c:1989 [inline]
dev_change_name+0x3c3/0x870 net/core/dev.c:1211
dev_ifsioc+0x800/0xf70 net/core/dev_ioctl.c:376
dev_ioctl+0x3d9/0xf80 net/core/dev_ioctl.c:542
sock_do_ioctl+0x160/0x260 net/socket.c:1213
sock_ioctl+0x3f9/0x670 net/socket.c:1316
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x19e/0x210 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3f/0x90 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x72/0xdc

The buggy address belongs to the object at ffff888105b0e400
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 16 bytes inside of
freed 1024-byte region [ffff888105b0e400, ffff888105b0e800)

The buggy address belongs to the physical page:
head:ffffea000416c200 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x200000000010200(slab|head|node=0|zone=2)
raw: 0200000000010200 ffff8881000430c0 ffffea00044c7010 ffffea0004510e10
raw: 0000000000000000 00000000000a000a 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff888105b0e300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888105b0e380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888105b0e400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888105b0e480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888105b0e500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

In summary, this patch solves those use-after-free by

1. Re-implement the nfc_llcp_find_local(). The current version does not
grab the reference when getting the local from the linked list. For
example, the llcp_sock_bind() gets the reference like below:

// llcp_sock_bind()

local = nfc_llcp_find_local(dev); // A
..... \
| raceable
..... /
llcp_sock->local = nfc_llcp_local_get(local); // B

There is an apparent race window that one can drop the reference
and free the local object fetched in (A) before (B) gets the reference.

2. Some callers of the nfc_llcp_find_local() do not grab the reference
at all. For example, the nfc_genl_llc_{{get/set}_params/sdreq} functions.
We add the nfc_llcp_local_put() for them. Moreover, we add the necessary
error handling function to put the reference.

3. Add the nfc_llcp_remove_local() helper. The local object is removed
from the linked list in local_release() when all reference is gone. This
patch removes it when nfc_llcp_unregister_device() is called.

Therefore, every caller of nfc_llcp_find_local() will get a reference
even when the nfc_llcp_unregister_device() is called. This promises no
use-after-free for the local object is ever possible.

Fixes: 52feb444a903 ("NFC: Extend netlink interface for LTO, RW, and MIUX parameters support")
Fixes: c7aa12252f51 ("NFC: Take a reference on the LLCP local pointer when creating a socket")
Signed-off-by: Lin Ma <linma@zju.edu.cn>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: llcp: fix possible use of uninitialized variable in nfc_llcp_send_connect()

If sock->service_name is NULL, the local variable
service_name_tlv_length will not be assigned by nfc_llcp_build_tlv(),
later leading to using value frmo the stack. Smatch warning:

net/nfc/llcp_commands.c:442 nfc_llcp_send_connect() error: uninitialized symbol 'service_name_tlv_length'.

Fixes: de9e5aeb4f40 ("NFC: llcp: Fix usage of llcp_add_tlv()")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: drop unneeded debug prints

ftrace is a preferred and standard way to debug entering and exiting
functions so drop useless debug prints.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

nfc: constify several pointers to u8, char and sk_buff

Several functions receive pointers to u8, char or sk_buff but do not
modify the contents so make them const. This allows doing the same for
local variables and in total makes the code a little bit safer.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13

Based on 2 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not see http www gnu org licenses

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details [based]
[from] [clk] [highbank] [c] you should have received a copy of the
gnu general public license along with this program if not see http
www gnu org licenses

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 355 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Jilayne Lovejoy <opensource@jilayne.com>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190519154041.837383322@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

net: nfc: Fix NULL dereference on nfc_llcp_build_tlv fails

KASAN report this:

BUG: KASAN: null-ptr-deref in nfc_llcp_build_gb+0x37f/0x540 [nfc]
Read of size 3 at addr 0000000000000000 by task syz-executor.0/5401

CPU: 0 PID: 5401 Comm: syz-executor.0 Not tainted 5.0.0-rc7+ #45
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0xfa/0x1ce lib/dump_stack.c:113
kasan_report+0x171/0x18d mm/kasan/report.c:321
memcpy+0x1f/0x50 mm/kasan/common.c:130
nfc_llcp_build_gb+0x37f/0x540 [nfc]
nfc_llcp_register_device+0x6eb/0xb50 [nfc]
nfc_register_device+0x50/0x1d0 [nfc]
nfcsim_device_new+0x394/0x67d [nfcsim]
? 0xffffffffc1080000
nfcsim_init+0x6b/0x1000 [nfcsim]
do_one_initcall+0xfa/0x5ca init/main.c:887
do_init_module+0x204/0x5f6 kernel/module.c:3460
load_module+0x66b2/0x8570 kernel/module.c:3808
__do_sys_finit_module+0x238/0x2a0 kernel/module.c:3902
do_syscall_64+0x147/0x600 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x462e99
Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9cb79dcc58 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
RAX: ffffffffffffffda RBX: 000000000073bf00 RCX: 0000000000462e99
RDX: 0000000000000000 RSI: 0000000020000280 RDI: 0000000000000003
RBP: 00007f9cb79dcc70 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f9cb79dd6bc
R13: 00000000004bcefb R14: 00000000006f7030 R15: 0000000000000004

nfc_llcp_build_tlv will return NULL on fails, caller should check it,
otherwise will trigger a NULL dereference.

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: eda21f16a5ed ("NFC: Set MIU and RW values from CONNECT and CC LLCP frames")
Fixes: d646960f7986 ("NFC: Initial LLCP support")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/nfc: Avoid stalls when nfc_alloc_send_skb() returned NULL.

syzbot is reporting stalls at nfc_llcp_send_ui_frame() [1]. This is
because nfc_llcp_send_ui_frame() is retrying the loop without any delay
when nonblocking nfc_alloc_send_skb() returned NULL.

Since there is no need to use MSG_DONTWAIT if we retry until
sock_alloc_send_pskb() succeeds, let's use blocking call.
Also, in case an unexpected error occurred, let's break the loop
if blocking nfc_alloc_send_skb() failed.

[1] https://syzkaller.appspot.com/bug?id=4a131cc571c3733e0eff6bc673f4e36ae48f19c6

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: syzbot <syzbot+d29d18215e477cfbfbdd@syzkaller.appspotmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

NFC: llcp: Limit size of SDP URI

The tlv_len is u8, so we need to limit the size of the SDP URI. Enforce
this both in the NLA policy and in the code that performs the allocation
and copy, to avoid writing past the end of the allocated buffer.

Fixes: d9b8d8e19b073 ("NFC: llcp: Service Name Lookup netlink interface")
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

networking: introduce and use skb_put_data()

A common pattern with skb_put() is to just want to memcpy()
some data into the new space, introduce skb_put_data() for
this.

An spatch similar to the one for skb_put_zero() converts many
of the places using it:

@@
identifier p, p2;
expression len, skb, data;
type t, t2;
@@
(
-p = skb_put(skb, len);
+p = skb_put_data(skb, data, len);
|
-p = (t)skb_put(skb, len);
+p = skb_put_data(skb, data, len);
)
(
p2 = (t2)p;
-memcpy(p2, data, len);
|
-memcpy(p, data, len);
)

@@
type t, t2;
identifier p, p2;
expression skb, data;
@@
t *p;
...
(
-p = skb_put(skb, sizeof(t));
+p = skb_put_data(skb, data, sizeof(t));
|
-p = (t *)skb_put(skb, sizeof(t));
+p = skb_put_data(skb, data, sizeof(t));
)
(
p2 = (t2)p;
-memcpy(p2, data, sizeof(*p));
|
-memcpy(p, data, sizeof(*p));
)

@@
expression skb, len, data;
@@
-memcpy(skb_put(skb, len), data, len);
+skb_put_data(skb, data, len);

(again, manually post-processed to retain some comments)

Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

NFC: llcp: Fix 2 memory leaks

Once copied into the sk_buff data area using llcp_add_tlv(), the
allocated TLVs must be freed.

With this patch nfc_llcp_send_connect() and nfc_llcp_send_cc() don't
return immediately on success and now free the allocated TLVs.

Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: llcp: Fix usage of llcp_add_tlv()

In functions using llcp_add_tlv(), a skb pointer could be set to NULL
and then reuse afterward.

With this patch, the skb pointer returned by llcp_add_tlv() is ignored
since it can only be the passed skb pointer or NULL when the passed TLV
is NULL. There is also no need to check for the TLV pointer as this is
done by llcp_add_tlv().

Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: Use GFP_USER for user-controlled kmalloc

These two functions are called in sendmsg path, and the
'len' is passed from user-space, so we should not allow
malicious users to OOM kernel on purpose.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Julian Calaby <julian.calaby@gmail.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: Fix warning "warning: incorrect type in assignment"

Fix warnings:
net/nfc/llcp_commands.c:421:14: warning: incorrect type in assignment (different base types)
net/nfc/llcp_commands.c:421:14: expected unsigned short [unsigned] [usertype] miux
net/nfc/llcp_commands.c:421:14: got restricted __be16
net/nfc/llcp_commands.c:477:14: warning: incorrect type in assignment (different base types)
net/nfc/llcp_commands.c:477:14: expected unsigned short [unsigned] [usertype] miux
net/nfc/llcp_commands.c:477:14: got restricted __be16

Procedure to reproduce:
make ARCH=x86_64 allmodconfig
make C=1 CF=-D__CHECK_ENDIAN__

Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

new helper: memcpy_from_msg()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

NFC: Add RAW socket type support for SOCKPROTO_RAW

This allows for a more generic NFC sniffing by using SOCKPROTO_RAW
SOCK_RAW to read RAW NFC frames. This is for sniffing anything but LLCP
(HCI, NCI, etc...).

Signed-off-by: Hiren Tandel <hirent@marvell.com>
Signed-off-by: Rahul Tank <rahult@marvell.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: llcp: Use default MIU if none was specified on connect

If MIUX is not present in CONNECT or CC use default MIU value (128)
instead of one announced durring link setup.

This was affecting Bluetooth handover with Android 4.3+ NCI stack.

Signed-off-by: Szymon Janc <szymon.janc@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: llcp: Fix possible memory leak while sending I frames

If sending was not completed due to low memory condition msg_data
was not free before returning from function.

Signed-off-by: Szymon Janc <szymon.janc@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

nfc: Fix FSF address in file headers

Several files refer to an old address for the Free Software Foundation
in the file header comment. Resolve by replacing the address with
the URL <http://www.gnu.org/licenses/> so that we do not have to keep
updating the header comments anytime the address changes.

CC: linux-wireless@vger.kernel.org
CC: Lauro Ramos Venancio <lauro.venancio@openbossa.org>
CC: Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
CC: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

NFC: Rename nfc_llcp_disconnect() to nfc_llcp_send_disconnect()

nfc_llcp_send_disconnect() already exists but is not used.
nfc_llcp_disconnect() naming is not consistent with other PDU
sending functions.
This patch removes nfc_llcp_send_disconnect() and renames
nfc_llcp_disconnect()

Signed-off-by: Thierry Escande <thierry.escande@linux.intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: Move LLCP code to the NFC top level diirectory

And stop making it optional. LLCP is a fundamental part of the NFC
specifications and making it optional does not make much sense.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>