nfc: llcp: fix nfc_llcp_setsockopt() unsafe copies

syzbot reported unsafe calls to copy_from_sockptr() [1]

Use copy_safe_from_sockptr() instead.

[1]

BUG: KASAN: slab-out-of-bounds in copy_from_sockptr_offset include/linux/sockptr.h:49 [inline]
BUG: KASAN: slab-out-of-bounds in copy_from_sockptr include/linux/sockptr.h:55 [inline]
BUG: KASAN: slab-out-of-bounds in nfc_llcp_setsockopt+0x6c2/0x850 net/nfc/llcp_sock.c:255
Read of size 4 at addr ffff88801caa1ec3 by task syz-executor459/5078

CPU: 0 PID: 5078 Comm: syz-executor459 Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
print_address_description mm/kasan/report.c:377 [inline]
print_report+0x169/0x550 mm/kasan/report.c:488
kasan_report+0x143/0x180 mm/kasan/report.c:601
copy_from_sockptr_offset include/linux/sockptr.h:49 [inline]
copy_from_sockptr include/linux/sockptr.h:55 [inline]
nfc_llcp_setsockopt+0x6c2/0x850 net/nfc/llcp_sock.c:255
do_sock_setsockopt+0x3b1/0x720 net/socket.c:2311
__sys_setsockopt+0x1ae/0x250 net/socket.c:2334
__do_sys_setsockopt net/socket.c:2343 [inline]
__se_sys_setsockopt net/socket.c:2340 [inline]
__x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2340
do_syscall_64+0xfd/0x240
entry_SYSCALL_64_after_hwframe+0x6d/0x75
RIP: 0033:0x7f7fac07fd89
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 91 18 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff660eb788 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f7fac07fd89
RDX: 0000000000000000 RSI: 0000000000000118 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000002 R09: 0000000000000000
R10: 0000000020000a80 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240408082845.3957374-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

nfc: Do not send datagram if socket state isn't LLCP_BOUND

As we know we cannot send the datagram (state can be set to LLCP_CLOSED
by nfc_llcp_socket_release()), there is no need to proceed further.

Thus, bail out early from llcp_sock_sendmsg().

Signed-off-by: Siddh Raman Pant <code@siddh.me>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Suman Ghosh <sumang@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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>

net: remove noblock parameter from skb_recv_datagram()

skb_recv_datagram() has two parameters 'flags' and 'noblock' that are
merged inside skb_recv_datagram() by 'flags | (noblock ? MSG_DONTWAIT : 0)'

As 'flags' may contain MSG_DONTWAIT as value most callers split the 'flags'
into 'flags' and 'noblock' with finally obsolete bit operations like this:

skb_recv_datagram(sk, flags & ~MSG_DONTWAIT, flags & MSG_DONTWAIT, &rc);

And this is not even done consistently with the 'flags' parameter.

This patch removes the obsolete and costly splitting into two parameters
and only performs bit operations when really needed on the caller side.

One missing conversion thankfully reported by kernel test robot. I missed
to enable kunit tests to build the mctp code.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: llcp: Revert "NFC: Keep socket alive until the DISC PDU is actually sent"

This reverts commit 17f7ae16aef1f58bc4af4c7a16b8778a91a30255.

The commit brought a new socket state LLCP_DISCONNECTING, which was
never set, only read, so socket could never set to such state.

Remove the dead code.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: llcp: protect nfc_llcp_sock_unlink() calls

nfc_llcp_sock_link() is called in all paths (bind/connect) as a last
action, still protected with lock_sock(). When cleaning up in
llcp_sock_release(), call nfc_llcp_sock_unlink() in a mirrored way:
earlier and still under the lock_sock().

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: llcp: use centralized exiting of bind on errors

Coding style encourages centralized exiting of functions, so rewrite
llcp_sock_bind() error paths to use such pattern. This reduces the
duplicated cleanup code, make success path visually shorter and also
cleans up the errors in proper order (in reversed way from
initialization).

No functional impact expected.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: llcp: simplify llcp_sock_connect() error paths

The llcp_sock_connect() error paths were using a mixed way of central
exit (goto) and cleanup

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: llcp: nullify llcp_sock->dev on connect() error paths

Nullify the llcp_sock->dev on llcp_sock_connect() error paths,
symmetrically to the code llcp_sock_bind(). The non-NULL value of
llcp_sock->dev is used in a few places to check whether the socket is
still valid.

There was no particular issue observed with missing NULL assignment in
connect() error path, however a similar case - in the bind() error path
- was triggereable. That one was fixed in commit 4ac06a1e013c ("nfc:
fix NULL ptr dereference in llcp_sock_getname() after failed connect"),
so the change here seems logical as well.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: llcp: fix NULL error pointer dereference on sendmsg() after failed bind()

Syzbot detected a NULL pointer dereference of nfc_llcp_sock->dev pointer
(which is a 'struct nfc_dev *') with calls to llcp_sock_sendmsg() after
a failed llcp_sock_bind(). The message being sent is a SOCK_DGRAM.

KASAN report:

BUG: KASAN: null-ptr-deref in nfc_alloc_send_skb+0x2d/0xc0
Read of size 4 at addr 00000000000005c8 by task llcp_sock_nfc_a/899

CPU: 5 PID: 899 Comm: llcp_sock_nfc_a Not tainted 5.16.0-rc6-next-20211224-00001-gc6437fbf18b0 #125
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x45/0x59
? nfc_alloc_send_skb+0x2d/0xc0
__kasan_report.cold+0x117/0x11c
? mark_lock+0x480/0x4f0
? nfc_alloc_send_skb+0x2d/0xc0
kasan_report+0x38/0x50
nfc_alloc_send_skb+0x2d/0xc0
nfc_llcp_send_ui_frame+0x18c/0x2a0
? nfc_llcp_send_i_frame+0x230/0x230
? __local_bh_enable_ip+0x86/0xe0
? llcp_sock_connect+0x470/0x470
? llcp_sock_connect+0x470/0x470
sock_sendmsg+0x8e/0xa0
____sys_sendmsg+0x253/0x3f0
...

The issue was visible only with multiple simultaneous calls to bind() and
sendmsg(), which resulted in most of the bind() calls to fail. The
bind() was failing on checking if there is available WKS/SDP/SAP
(respective bit in 'struct nfc_llcp_local' fields). When there was no
available WKS/SDP/SAP, the bind returned error but the sendmsg() to such
socket was able to trigger mentioned NULL pointer dereference of
nfc_llcp_sock->dev.

The code looks simply racy and currently it protects several paths
against race with checks for (!nfc_llcp_sock->local) which is NULL-ified
in error paths of bind(). The llcp_sock_sendmsg() did not have such
check but called function nfc_llcp_send_ui_frame() had, although not
protected with lock_sock().

Therefore the race could look like (same socket is used all the time):
CPU0 CPU1
==== ====
llcp_sock_bind()
- lock_sock()
- success
- release_sock()
- return 0
llcp_sock_sendmsg()
- lock_sock()
- release_sock()
llcp_sock_bind(), same socket
- lock_sock()
- error
- nfc_llcp_send_ui_frame()
- if (!llcp_sock->local)
- llcp_sock->local = NULL
- nfc_put_device(dev)
- dereference llcp_sock->dev
- release_sock()
- return -ERRNO

The nfc_llcp_send_ui_frame() checked llcp_sock->local outside of the
lock, which is racy and ineffective check. Instead, its caller
llcp_sock_sendmsg(), should perform the check inside lock_sock().

Reported-and-tested-by: syzbot+7f23bcddf626e0593a39@syzkaller.appspotmail.com
Fixes: b874dec21d1c ("NFC: Implement LLCP connection less Tx path")
Cc: <stable@vger.kernel.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: fix NULL ptr dereference in llcp_sock_getname() after failed connect

It's possible to trigger NULL pointer dereference by local unprivileged
user, when calling getsockname() after failed bind() (e.g. the bind
fails because LLCP_SAP_MAX used as SAP):

BUG: kernel NULL pointer dereference, address: 0000000000000000
CPU: 1 PID: 426 Comm: llcp_sock_getna Not tainted 5.13.0-rc2-next-20210521+ #9
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1 04/01/2014
Call Trace:
llcp_sock_getname+0xb1/0xe0
__sys_getpeername+0x95/0xc0
? lockdep_hardirqs_on_prepare+0xd5/0x180
? syscall_enter_from_user_mode+0x1c/0x40
__x64_sys_getpeername+0x11/0x20
do_syscall_64+0x36/0x70
entry_SYSCALL_64_after_hwframe+0x44/0xae

This can be reproduced with Syzkaller C repro (bind followed by
getpeername):
https://syzkaller.appspot.com/x/repro.c?x=14def446e00000

Cc: <stable@vger.kernel.org>
Fixes: d646960f7986 ("NFC: Initial LLCP support")
Reported-by: syzbot+80fb126e7f7d8b1a5914@syzkaller.appspotmail.com
Reported-by: butt3rflyh4ck <butterflyhuangxx@gmail.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20210531072138.5219-1-krzysztof.kozlowski@canonical.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/nfc: fix use-after-free llcp_sock_bind/connect

Commits 8a4cd82d ("nfc: fix refcount leak in llcp_sock_connect()")
and c33b1cc62 ("nfc: fix refcount leak in llcp_sock_bind()")
fixed a refcount leak bug in bind/connect but introduced a
use-after-free if the same local is assigned to 2 different sockets.

This can be triggered by the following simple program:
int sock1 = socket( AF_NFC, SOCK_STREAM, NFC_SOCKPROTO_LLCP );
int sock2 = socket( AF_NFC, SOCK_STREAM, NFC_SOCKPROTO_LLCP );
memset( &addr, 0, sizeof(struct sockaddr_nfc_llcp) );
addr.sa_family = AF_NFC;
addr.nfc_protocol = NFC_PROTO_NFC_DEP;
bind( sock1, (struct sockaddr*) &addr, sizeof(struct sockaddr_nfc_llcp) )
bind( sock2, (struct sockaddr*) &addr, sizeof(struct sockaddr_nfc_llcp) )
close(sock1);
close(sock2);

Fix this by assigning NULL to llcp_sock->local after calling
nfc_llcp_local_put.

This addresses CVE-2021-23134.

Reported-by: Or Cohen <orcohen@paloaltonetworks.com>
Reported-by: Nadav Markus <nmarkus@paloaltonetworks.com>
Fixes: c33b1cc62 ("nfc: fix refcount leak in llcp_sock_bind()")
Signed-off-by: Or Cohen <orcohen@paloaltonetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: Avoid endless loops caused by repeated llcp_sock_connect()

When sock_wait_state() returns -EINPROGRESS, "sk->sk_state" is
LLCP_CONNECTING. In this case, llcp_sock_connect() is repeatedly invoked,
nfc_llcp_sock_link() will add sk to local->connecting_sockets twice.
sk->sk_node->next will point to itself, that will make an endless loop
and hang-up the system.
To fix it, check whether sk->sk_state is LLCP_CONNECTING in
llcp_sock_connect() to avoid repeated invoking.

Fixes: b4011239a08e ("NFC: llcp: Fix non blocking sockets connections")
Reported-by: "kiyin(尹亮)" <kiyin@tencent.com>
Link: https://www.openwall.com/lists/oss-security/2020/11/01/1
Cc: <stable@vger.kernel.org> #v3.11
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: fix memory leak in llcp_sock_connect()

In llcp_sock_connect(), use kmemdup to allocate memory for
"llcp_sock->service_name". The memory is not released in the sock_unlink
label of the subsequent failure branch.
As a result, memory leakage occurs.

fix CVE-2020-25672

Fixes: d646960f7986 ("NFC: Initial LLCP support")
Reported-by: "kiyin(尹亮)" <kiyin@tencent.com>
Link: https://www.openwall.com/lists/oss-security/2020/11/01/1
Cc: <stable@vger.kernel.org> #v3.3
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: fix refcount leak in llcp_sock_connect()

nfc_llcp_local_get() is invoked in llcp_sock_connect(),
but nfc_llcp_local_put() is not invoked in subsequent failure branches.
As a result, refcount leakage occurs.
To fix it, add calling nfc_llcp_local_put().

fix CVE-2020-25671
Fixes: c7aa12252f51 ("NFC: Take a reference on the LLCP local pointer when creating a socket")
Reported-by: "kiyin(尹亮)" <kiyin@tencent.com>
Link: https://www.openwall.com/lists/oss-security/2020/11/01/1
Cc: <stable@vger.kernel.org> #v3.6
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: fix refcount leak in llcp_sock_bind()

nfc_llcp_local_get() is invoked in llcp_sock_bind(),
but nfc_llcp_local_put() is not invoked in subsequent failure branches.
As a result, refcount leakage occurs.
To fix it, add calling nfc_llcp_local_put().

fix CVE-2020-25670
Fixes: c7aa12252f51 ("NFC: Take a reference on the LLCP local pointer when creating a socket")
Reported-by: "kiyin(尹亮)" <kiyin@tencent.com>
Link: https://www.openwall.com/lists/oss-security/2020/11/01/1
Cc: <stable@vger.kernel.org> #v3.6
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: pass a sockptr_t into ->setsockopt

Rework the remaining setsockopt code to pass a sockptr_t instead of a
plain user pointer. This removes the last remaining set_fs(KERNEL_DS)
outside of architecture specific code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Stefan Schmidt <stefan@datenfreihafen.org> [ieee802154]
Acked-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: make ->{get,set}sockopt in proto_ops optional

Just check for a NULL method instead of wiring up
sock_no_{get,set}sockopt.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: use skb_queue_empty_lockless() in poll() handlers

Many poll() handlers are lockless. Using skb_queue_empty_lockless()
instead of skb_queue_empty() is more appropriate.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: fix memory leak in llcp_sock_bind()

sysbot reported a memory leak after a bind() has failed.

While we are at it, abort the operation if kmemdup() has failed.

BUG: memory leak
unreferenced object 0xffff888105d83ec0 (size 32):
comm "syz-executor067", pid 7207, jiffies 4294956228 (age 19.430s)
hex dump (first 32 bytes):
00 69 6c 65 20 72 65 61 64 00 6e 65 74 3a 5b 34 .ile read.net:[4
30 32 36 35 33 33 30 39 37 5d 00 00 00 00 00 00 026533097]......
backtrace:
[<0000000036bac473>] kmemleak_alloc_recursive /./include/linux/kmemleak.h:43 [inline]
[<0000000036bac473>] slab_post_alloc_hook /mm/slab.h:522 [inline]
[<0000000036bac473>] slab_alloc /mm/slab.c:3319 [inline]
[<0000000036bac473>] __do_kmalloc /mm/slab.c:3653 [inline]
[<0000000036bac473>] __kmalloc_track_caller+0x169/0x2d0 /mm/slab.c:3670
[<000000000cd39d07>] kmemdup+0x27/0x60 /mm/util.c:120
[<000000008e57e5fc>] kmemdup /./include/linux/string.h:432 [inline]
[<000000008e57e5fc>] llcp_sock_bind+0x1b3/0x230 /net/nfc/llcp_sock.c:107
[<000000009cb0b5d3>] __sys_bind+0x11c/0x140 /net/socket.c:1647
[<00000000492c3bbc>] __do_sys_bind /net/socket.c:1658 [inline]
[<00000000492c3bbc>] __se_sys_bind /net/socket.c:1656 [inline]
[<00000000492c3bbc>] __x64_sys_bind+0x1e/0x30 /net/socket.c:1656
[<0000000008704b2a>] do_syscall_64+0x76/0x1a0 /arch/x86/entry/common.c:296
[<000000009f4c57a4>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: 30cc4587659e ("NFC: Move LLCP code to the NFC top level diirectory")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

nfc: enforce CAP_NET_RAW for raw sockets

When creating a raw AF_NFC socket, CAP_NET_RAW needs to be checked
first.

Signed-off-by: Ori Nimron <orinimron123@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

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>

nfc: Fix to check for kmemdup failure

In case of kmemdup failure while setting the service name the patch
returns -ENOMEM upstream for processing.

Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>

Revert "net: simplify sock_poll_wait"

This reverts commit dd979b4df817e9976f18fb6f9d134d6bc4a3c317.

This broke tcp_poll for SMC fallback: An AF_SMC socket establishes an
internal TCP socket for the initial handshake with the remote peer.
Whenever the SMC connection can not be established this TCP socket is
used as a fallback. All socket operations on the SMC socket are then
forwarded to the TCP socket. In case of poll, the file->private_data
pointer references the SMC socket because the TCP socket has no file
assigned. This causes tcp_poll to wait on the wrong socket.

Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: simplify sock_poll_wait

The wait_address argument is always directly derived from the filp
argument, so remove it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL

The poll() changes were not well thought out, and completely
unexplained. They also caused a huge performance regression, because
"->poll()" was no longer a trivial file operation that just called down
to the underlying file operations, but instead did at least two indirect
calls.

Indirect calls are sadly slow now with the Spectre mitigation, but the
performance problem could at least be largely mitigated by changing the
"->get_poll_head()" operation to just have a per-file-descriptor pointer
to the poll head instead. That gets rid of one of the new indirections.

But that doesn't fix the new complexity that is completely unwarranted
for the regular case. The (undocumented) reason for the poll() changes
was some alleged AIO poll race fixing, but we don't make the common case
slower and more complex for some uncommon special case, so this all
really needs way more explanations and most likely a fundamental
redesign.

[ This revert is a revert of about 30 different commits, not reverted
individually because that would just be unnecessarily messy - Linus ]

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

net/nfc: convert to ->poll_mask

Signed-off-by: Christoph Hellwig <hch@lst.de>

net: make getname() functions return length rather than use int* parameter

Changes since v1:
Added changes in these files:
drivers/infiniband/hw/usnic/usnic_transport.c
drivers/staging/lustre/lnet/lnet/lib-socket.c
drivers/target/iscsi/iscsi_target_login.c
drivers/vhost/net.c
fs/dlm/lowcomms.c
fs/ocfs2/cluster/tcp.c
security/tomoyo/network.c

Before:
All these functions either return a negative error indicator,
or store length of sockaddr into "int *socklen" parameter
and return zero on success.

"int *socklen" parameter is awkward. For example, if caller does not
care, it still needs to provide on-stack storage for the value
it does not need.

None of the many FOO_getname() functions of various protocols
ever used old value of *socklen. They always just overwrite it.

This change drops this parameter, and makes all these functions, on success,
return length of sockaddr. It's always >= 0 and can be differentiated
from an error.

Tests in callers are changed from "if (err)" to "if (err < 0)", where needed.

rpc_sockname() lost "int buflen" parameter, since its only use was
to be passed to kernel_getsockname() as &buflen and subsequently
not used in any way.

Userspace API is not changed.

text data bss dec hex filename
30108430 2633624 873672 33615726 200ef6e vmlinux.before.o
30108109 2633612 873672 33615393 200ee21 vmlinux.o

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
CC: David S. Miller <davem@davemloft.net>
CC: linux-kernel@vger.kernel.org
CC: netdev@vger.kernel.org
CC: linux-bluetooth@vger.kernel.org
CC: linux-decnet-user@lists.sourceforge.net
CC: linux-wireless@vger.kernel.org
CC: linux-rdma@vger.kernel.org
CC: linux-sctp@vger.kernel.org
CC: linux-nfs@vger.kernel.org
CC: linux-x25@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

vfs: do bulk POLL* -> EPOLL* replacement

This is the mindless scripted replacement of kernel use of POLL*
variables as described by Al, done by this script:

for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do
L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'`
for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done
done

with de-mangling cleanups yet to come.

NOTE! On almost all architectures, the EPOLL* constants have the same
values as the POLL* constants do. But they keyword here is "almost".
For various bad reasons they aren't the same, and epoll() doesn't
actually work quite correctly in some cases due to this on Sparc et al.

The next patch from Al will sort out the final differences, and we
should be all done.

Scripted-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

net: annotate ->poll() instances

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

NFC: Add sockaddr length checks before accessing sa_family in bind handlers

Verify that the caller-provided sockaddr structure is large enough to
contain the sa_family field, before accessing it in bind() handlers of the
AF_NFC socket. Since the syscall doesn't enforce a minimum size of the
corresponding memory region, very short sockaddrs (zero or one byte long)
result in operating on uninitialized memory while referencing .sa_family.

Signed-off-by: Mateusz Jurczyk <mjurczyk@google.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

nfc: Fix the sockaddr length sanitization in llcp_sock_connect

Fix the sockaddr length verification in the connect() handler of NFC/LLCP
sockets, to compare against the size of the actual structure expected on
input (sockaddr_nfc_llcp) instead of its shorter version (sockaddr_nfc).

Both structures are defined in include/uapi/linux/nfc.h. The fields
specific to the _llcp extended struct are as follows:

276 __u8 dsap; /* Destination SAP, if known */
277 __u8 ssap; /* Source SAP to be bound to */
278 char service_name[NFC_LLCP_MAX_SERVICE_NAME]; /* Service name URI */;
279 size_t service_name_len;

If the caller doesn't provide a sufficiently long sockaddr buffer, these
fields remain uninitialized (and they currently originate from the stack
frame of the top-level sys_connect handler). They are then copied by
llcp_sock_connect() into internal storage (nfc_llcp_sock structure), and
could be subsequently read back through the user-mode getsockname()
function (handled by llcp_sock_getname()). This would result in the
disclosure of up to ~70 uninitialized bytes from the kernel stack to
user-mode clients capable of creating AFC_NFC sockets.

Signed-off-by: Mateusz Jurczyk <mjurczyk@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

net: Work around lockdep limitation in sockets that use sockets

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 <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h>

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

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

NFC: Close a race condition in llcp_sock_getname()

llcp_sock_getname() checks llcp_sock->dev to make sure
llcp_sock is already connected or bound, however, we could
be in the middle of llcp_sock_bind() where llcp_sock->dev
is bound and llcp_sock->service_name_len is set,
but llcp_sock->service_name is not, in this case we would
lead to copy some bytes from a NULL pointer.

Just lock the sock since this is not a hot path anyway.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

net: rename SOCK_ASYNC_NOSPACE and SOCK_ASYNC_WAITDATA

This patch is a cleanup to make following patch easier to
review.

Goal is to move SOCK_ASYNC_NOSPACE and SOCK_ASYNC_WAITDATA
from (struct socket)->flags to a (struct socket_wq)->flags
to benefit from RCU protection in sock_wake_async()

To ease backports, we rename both constants.

Two new helpers, sk_set_bit(int nr, struct sock *sk)
and sk_clear_bit(int net, struct sock *sk) are added so that
following patch can change their implementation.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: Pass kern from net_proto_family.create to sk_alloc

In preparation for changing how struct net is refcounted
on kernel sockets pass the knowledge that we are creating
a kernel socket from sock_create_kern through to sk_alloc.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: Remove iocb argument from sendmsg and recvmsg

After TIPC doesn't depend on iocb argument in its internal
implementations of sendmsg() and recvmsg() hooks defined in proto
structure, no any user is using iocb argument in them at all now.
Then we can drop the redundant iocb argument completely from kinds of
implementations of both sendmsg() and recvmsg() in the entire
networking stack.

Cc: Christoph Hellwig <hch@lst.de>
Suggested-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

NFC: llcp: Use list_for_each_entry in llcp_accept_poll

list_for_each_entry_safe() is necessary if list objects are deleted from
the list while traversing it. Not the case here, so we can use the base
list_for_each_entry variant.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

net: Add and use skb_copy_datagram_msg() helper.

This encapsulates all of the skb_copy_datagram_iovec() callers
with call argument signature "skb, offset, msghdr->msg_iov, length".

When we move to iov_iters in the networking, the iov_iter object will
sit in the msghdr.

Having a helper like this means there will be less places to touch
during that transformation.

Based upon descriptions and patch from Al Viro.

Signed-off-by: David S. Miller <davem@davemloft.net>

net: add build-time checks for msg->msg_name size

This is a follow-up patch to f3d3342602f8bc ("net: rework recvmsg
handler msg_name and msg_namelen logic").

DECLARE_SOCKADDR validates that the structure we use for writing the
name information to is not larger than the buffer which is reserved
for msg->msg_name (which is 128 bytes). Also use DECLARE_SOCKADDR
consistently in sendmsg code paths.

Signed-off-by: Steffen Hurrle <steffen@hurrle.net>
Suggested-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

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: 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>

net: rework recvmsg handler msg_name and msg_namelen logic

This patch now always passes msg->msg_namelen as 0. recvmsg handlers must
set msg_namelen to the proper size <= sizeof(struct sockaddr_storage)
to return msg_name to the user.

This prevents numerous uninitialized memory leaks we had in the
recvmsg handlers and makes it harder for new code to accidentally leak
uninitialized memory.

Optimize for the case recvfrom is called with NULL as address. We don't
need to copy the address at all, so set it to NULL before invoking the
recvmsg handler. We can do so, because all the recvmsg handlers must
cope with the case a plain read() is called on them. read() also sets
msg_name to NULL.

Also document these changes in include/linux/net.h as suggested by David
Miller.

Changes since RFC:

Set msg->msg_name = NULL if user specified a NULL in msg_name but had a
non-null msg_namelen in verify_iovec/verify_compat_iovec. This doesn't
affect sendto as it would bail out earlier while trying to copy-in the
address. It also more naturally reflects the logic by the callers of
verify_iovec.

With this change in place I could remove "
if (!uaddr || msg_sys->msg_namelen == 0)
msg->msg_name = NULL
".

This change does not alter the user visible error logic as we ignore
msg_namelen as long as msg_name is NULL.

Also remove two unnecessary curly brackets in ___sys_recvmsg and change
comments to netdev style.

Cc: David Miller <davem@davemloft.net>
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

NFC: llcp: Fix non blocking sockets connections

Without the new LLCP_CONNECTING state, non blocking sockets will be
woken up with a POLLHUP right after calling connect() because their
state is stuck at LLCP_CLOSED.
That prevents userspace from implementing any proper non blocking
socket based NFC p2p client.

Cc: stable@vger.kernel.org
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

NFC: Keep socket alive until the DISC PDU is actually sent

This patch keeps the socket alive and therefore does not remove
it from the sockets list in the local until the DISC PDU has been
actually sent. Otherwise we would reply with DM PDUs before sending
the DISC one.

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