This allows users to inforce encryption for SMB3 shares if a server
supports it.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>

Allow to decrypt transformed packets that are bigger than the big
buffer size. In particular it is used for read responses that can
only exceed the big buffer size.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>

Allow to decrypt transformed packets, find a corresponding mid
and process as usual further.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>

Since we have two different types of reads (pagecache and direct)
we need to process such responses differently after decryption of
a packet. The change allows to specify a callback that copies a read
payload data into preallocated pages.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>

We need to process read responses differently because the data
should go directly into preallocated pages. This can be done
by specifying a mid handle callback.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>

We need to recognize and parse transformed packets in demultiplex
thread to find a corresponsing mid and process it further.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>

This change allows to encrypt packets if it is required by a server
for SMB sessions or tree connections.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>

In order to allow encryption on SMB connection we need to exchange
a session key and generate encryption and decryption keys.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>

This will allow us to do protocol specific tranformations of packets
before sending to the server. For SMB3 it can be used to support
encryption.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>

Allocate and initialize SMB2 read request without RFC1001 length
field to directly call cifs_send_recv() rather than SendReceive2()
in a read codepath.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>

Do not process RFC1001 length in smb2_hdr_assemble() because
it is not a part of SMB2 header. This allows to cleanup the code
and adds a possibility combine several SMB2 packets into one
for compounding.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>

In order to simplify further encryption support we need to separate
RFC1001 length and SMB2 header when sending a request. Put the length
field in iov[0] and the rest of the packet into following iovs.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>

Now SendReceive2 frees the first iov and returns a response buffer
in it that increases a code complexity. Simplify this by making
a caller responsible for freeing request buffer itself and returning
a response buffer in a separate iov.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>

In order to support compounding and encryption we need to separate
RFC1001 length field and SMB2 header structure because the protocol
treats them differently. This change will allow to simplify parsing
of such complex SMB2 packets further.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>

Currently we call copy_page_to_iter() for uncached reading into a pipe.
This is wrong because it treats pages as VFS cache pages and copies references
rather than actual data. When we are trying to read from the pipe we end up
calling page_cache_pipe_buf_confirm() which returns -ENODATA. This error
is translated into 0 which is returned to a user.

This issue is reproduced by running xfs-tests suite (generic test #249)
against mount points with "cache=none". Fix it by mapping pages manually
and calling copy_to_iter() that copies data into the pipe.

Cc: Stable <stable@vger.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>

List soft dependencies of cifs so that mkinitrd and dracut can include
the required helper modules.
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Steve French <sfrench@samba.org>

The sha256 and cmac crypto modules are only needed for SMB2+, so move
the select statements to config CIFS_SMB2. Also select CRYPTO_AES
there as SMB2+ needs it.
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Steve French <sfrench@samba.org>

* CIFS_SMB2 depends on CIFS, which depends on INET and selects NLS. So
  these dependencies do not need to be repeated for CIFS_SMB2.
* CIFS_SMB311 depends on CIFS_SMB2, which depends on INET. So this
  dependency doesn't need to be repeated for CIFS_SMB311.
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Steve French <sfrench@samba.org>

Pull networking fixes from David Miller:

 1) Fix handling of interrupt status in stmmac driver. Just because we
    have masked the event from generating interrupts, doesn't mean the
    bit won't still be set in the interrupt status register. From Alexey
    Brodkin.

 2) Fix DMA API debugging splats in gianfar driver, from Arseny Solokha.

 3) Fix off-by-one error in __ip6_append_data(), from Vlad Yasevich.

 4) cls_flow does not match on icmpv6 codes properly, from Simon Horman.

 5) Initial MAC address can be set incorrectly in some scenerios, from
    Ivan Vecera.

 6) Packet header pointer arithmetic fix in ip6_tnl_parse_tlv_end_lim(),
    from Dan Carpenter.

 7) Fix divide by zero in __tcp_select_window(), from Eric Dumazet.

 8) Fix crash in iwlwifi when unregistering thermal zone, from Jens
    Axboe.

 9) Check for DMA mapping errors in starfire driver, from Alexey
    Khoroshilov.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (31 commits)
  tcp: fix 0 divide in __tcp_select_window()
  ipv6: pointer math error in ip6_tnl_parse_tlv_enc_lim()
  net: fix ndo_features_check/ndo_fix_features comment ordering
  net/sched: matchall: Fix configuration race
  be2net: fix initial MAC setting
  ipv6: fix flow labels when the traffic class is non-0
  net: thunderx: avoid dereferencing xcv when NULL
  net/sched: cls_flower: Correct matching on ICMPv6 code
  ipv6: Paritially checksum full MTU frames
  net/mlx4_core: Avoid command timeouts during VF driver device shutdown
  gianfar: synchronize DMA API usage by free_skb_rx_queue w/ gfar_new_page
  net: ethtool: add support for 2500BaseT and 5000BaseT link modes
  can: bcm: fix hrtimer/tasklet termination in bcm op removal
  net: adaptec: starfire: add checks for dma mapping errors
  net: phy: micrel: KSZ8795 do not set SUPPORTED_[Asym_]Pause
  can: Fix kernel panic at security_sock_rcv_skb
  net: macb: Fix 64 bit addressing support for GEM
  stmmac: Discard masked flags in interrupt status register
  net/mlx5e: Check ets capability before ets query FW command
  net/mlx5e: Fix update of hash function/key via ethtool
  ...

Pull fscache fixes from Al Viro.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fscache: Fix dead object requeue
  fscache: Clear outstanding writes when disabling a cookie
  FS-Cache: Initialise stores_lock in netfs cookie

syszkaller fuzzer was able to trigger a divide by zero, when
TCP window scaling is not enabled.

SO_RCVBUF can be used not only to increase sk_rcvbuf, also
to decrease it below current receive buffers utilization.

If mss is negative or 0, just return a zero TCP window.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Dmitry Vyukov  <dvyukov@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Casting is a high precedence operation but "off" and "i" are in terms of
bytes so we need to have some parenthesis here.

Fixes: fbfa743a ("ipv6: fix ip6_tnl_parse_tlv_enc_lim()")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Pull crypto fixes from Herbert Xu:
 "This fixes a bug in CBC/CTR on ARM64 that breaks chaining as well as a
  bug in the core API that causes registration failures when a driver
  unloads and then reloads an algorithm"

* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  crypto: arm64/aes-blk - honour iv_out requirement in CBC and CTR modes
  crypto: api - Clear CRYPTO_ALG_DEAD bit before registering an alg

Pull dmaengine fixes from Vinod Koul:
 "A couple of fixes showed up late in the cycle so sending them up and
  sending early in the week and not on Friday :).

  They fix a double lock in pl330 driver and runtime pm fixes for cppi
  driver"

* tag 'dmaengine-fix-4.10-rc7' of git://git.infradead.org/users/vkoul/slave-dma:
  dmaengine: pl330: fix double lock
  dmaengine: cppi41: Clean up pointless warnings
  dmaengine: cppi41: Fix oops in cppi41_runtime_resume
  dmaengine: cppi41: Fix runtime PM timeouts with USB mass storage

Commit cdba756f ("net: move ndo_features_check() close to
ndo_start_xmit()") inadvertently moved the doc comment for
.ndo_fix_features instead of .ndo_features_check. Fix the comment
ordering.

Fixes: cdba756f ("net: move ndo_features_check() close to ndo_start_xmit()")
Signed-off-by: Dimitris Michailidis <dmichail@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In the current version, the matchall internal state is split into two
structs: cls_matchall_head and cls_matchall_filter. This makes little
sense, as matchall instance supports only one filter, and there is no
situation where one exists and the other does not. In addition, that led
to some races when filter was deleted while packet was processed.

Unify that two structs into one, thus simplifying the process of matchall
creation and deletion. As a result, the new, delete and get callbacks have
a dummy implementation where all the work is done in destroy and change
callbacks, as was done in cls_cgroup.

Fixes: bf3994d2 ("net/sched: introduce Match-all classifier")
Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Yotam Gigi <yotamg@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Pull pin control fixes from Linus Walleij:
 "Another week, another set of pin control fixes. The subsystem has seen
  high patch-spot activity recently.

  The majority of the patches are for Intel, I vaguely think it mostly
  concern phones, tablets and maybe chromebooks and even laptops with
  this Intel Atom family chips.

  Driver fixes only:

   - one fix to the Berlin driver making the SD card work fully again.

   - one fix to the Allwinner/sunxi bias function: one premature change
     needs to be partially reverted.

   - the remaining four patches are to Intel embedded SoCs: baytrail
     (three patches) and merrifield (one patch): register access
     debounce fixes and a missing spinlock"

* tag 'pinctrl-v4.10-4' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: baytrail: Add missing spinlock usage in byt_gpio_irq_handler
  pinctrl: baytrail: Debounce register is one per community
  pinctrl: baytrail: Rectify debounce support (part 2)
  pinctrl: intel: merrifield: Add missed check in mrfld_config_set()
  pinctrl: sunxi: Don't enforce bias disable (for now)
  pinctrl: berlin-bg4ct: fix the value for "sd1a" of pin SCRD0_CRD_PRES

Recent commit 34393529 ("be2net: fix MAC addr setting on privileged
BE3 VFs") allows privileged BE3 VFs to set its MAC address during
initialization. Although the initial MAC for such VFs is already
programmed by parent PF the subsequent setting performed by VF is OK,
but in certain cases (after fresh boot) this command in VF can fail.

The MAC should be initialized only when:
1) no MAC is programmed (always except BE3 VFs during first init)
2) programmed MAC is different from requested (e.g. MAC is set when
   interface is down). In this case the initial MAC programmed by PF
   needs to be deleted.

The adapter->dev_mac contains MAC address currently programmed in HW so
it should be zeroed when the MAC is deleted from HW and should not be
filled when MAC is set when interface is down in be_mac_addr_set() as
no programming is performed in this case.

Example of failure without the fix (immediately after fresh boot):

# ip link set eth0 up  <- eth0 is BE3 PF
be2net 0000:01:00.0 eth0: Link is Up

# echo 1 > /sys/class/net/eth0/device/sriov_numvfs  <- Create 1 VF
...
be2net 0000:01:04.0: Emulex OneConnect(be3): VF  port 0

# ip link set eth8 up  <- eth8 is created privileged VF
be2net 0000:01:04.0: opcode 59-1 failed:status 1-76
RTNETLINK answers: Input/output error

# echo 0 > /sys/class/net/eth0/device/sriov_numvfs  <- Delete VF
iommu: Removing device 0000:01:04.0 from group 33
...

# echo 1 > /sys/class/net/eth0/device/sriov_numvfs  <- Create it again
iommu: Removing device 0000:01:04.0 from group 33
...

# ip link set eth8 up
be2net 0000:01:04.0 eth8: Link is Up

Initialization is now OK.

v2 - Corrected the comment and condition check suggested by Suresh & Harsha

Fixes: 34393529 ("be2net: fix MAC addr setting on privileged BE3 VFs")
Cc: Sathya Perla <sathya.perla@broadcom.com>
Cc: Ajit Khaparde <ajit.khaparde@broadcom.com>
Cc: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Cc: Somnath Kotur <somnath.kotur@broadcom.com>
Signed-off-by: Ivan Vecera <cera@cera.cz>
Acked-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Pull tracing fix from Steven Rostedt:
 "It was reported to me that the thread created by the hwlat tracer does
  not migrate after the first instance. I found that there was as small
  bug in the logic, and fixed it. It's minor, but should be fixed
  regardless. There's not much impact outside the hwlat tracer"

* tag 'trace-4.10-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Fix hwlat kthread migration

Pull input subsystem fixes from Dmitry Torokhov:
 "A fix for a crash in the wm97xx driver and synaptics-rmi4 will stop
  throwing erroneous warnings."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: synaptics-rmi4 - fix reversed conditions in enable/disable_irq_wake
  Input: wm97xx - make missing platform data non-fatal

Pull cgroup fix from Tejun Heo:
 "The cgroup creation path was getting the order of operations wrong and
  exposing cgroups which don't have their names set yet to controllers
  which can lead to NULL derefs.

  This contains the fix for the bug"

* 'for-4.10-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: don't online subsystems before cgroup_name/path() are operational

Pull percpu fix from Tejun Heo:
 "Douglas found and fixed a ref leak bug in percpu_ref_tryget[_live]().

  The bug is caused by storing the return value of atomic_long_inc_not_zero()
  into an int temp variable before returning it as a bool. The interim
  cast to int loses the upper bits and can lead to false negatives. As
  percpu_ref uses a high bit to mark a draining counter, this can happen
  relatively easily.

  Fixed by using bool for the temp variable"

* 'for-4.10-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
  percpu-refcount: fix reference leak during percpu-atomic transition

Pull libata fixes from Tejun Heo:
 "Three libata fixes: an error handling fix, blacklist addition for
  another fallout from upping the default max sectors, and fix for a
  sense data reporting bug which affects new harddrives which can report
  sense data"

* 'for-4.10-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata:
  ata: sata_mv:- Handle return value of devm_ioremap.
  libata: Fix ATA request sense
  libata: apply MAX_SEC_1024 to all CX1-JB*-HP devices

Pull HID fixes from Jiri Kosina:

 - regression fix (sleeping while atomic) for cp2112, from Johan Hovold

 - regression fix for proximity handling under certain circumstances in
   Wacom driver, from Jason Gerecke

 - functional fix for Logitech Rumblepad 2, from Ardinartsev Nikita

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid:
  HID: cp2112: fix gpio-callback error handling
  HID: cp2112: fix sleep-while-atomic
  HID: hid-lg: Fix immediate disconnection of Logitech Rumblepad 2
  HID: usbhid: Quirk a AMI virtual mouse and keyboard with ALWAYS_POLL
  HID: wacom: Fix poor prox handling in 'wacom_pl_irq'

Pull cifs fix from Steve French:
 "A small cifs fix for stable"

* 'for-next' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: initialize file_info_lock

Under some circumstances, an fscache object can become queued such that it
fscache_object_work_func() can be called once the object is in the
OBJECT_DEAD state.  This results in the kernel oopsing when it tries to
invoke the handler for the state (which is hard coded to 0x2).

The way this comes about is something like the following:

 (1) The object dispatcher is processing a work state for an object.  This
     is done in workqueue context.

 (2) An out-of-band event comes in that isn't masked, causing the object to
     be queued, say EV_KILL.

 (3) The object dispatcher finishes processing the current work state on
     that object and then sees there's another event to process, so,
     without returning to the workqueue core, it processes that event too.
     It then follows the chain of events that initiates until we reach
     OBJECT_DEAD without going through a wait state (such as
     WAIT_FOR_CLEARANCE).

     At this point, object->events may be 0, object->event_mask will be 0
     and oob_event_mask will be 0.

 (4) The object dispatcher returns to the workqueue processor, and in due
     course, this sees that the object's work item is still queued and
     invokes it again.

 (5) The current state is a work state (OBJECT_DEAD), so the dispatcher
     jumps to it - resulting in an OOPS.

When I'm seeing this, the work state in (1) appears to have been either
LOOK_UP_OBJECT or CREATE_OBJECT (object->oob_table is
fscache_osm_lookup_oob).

The window for (2) is very small:

 (A) object->event_mask is cleared whilst the event dispatch process is
     underway - though there's no memory barrier to force this to the top
     of the function.

     The window, therefore is from the time the object was selected by the
     workqueue processor and made requeueable to the time the mask was
     cleared.

 (B) fscache_raise_event() will only queue the object if it manages to set
     the event bit and the corresponding event_mask bit was set.

     The enqueuement is then deferred slightly whilst we get a ref on the
     object and get the per-CPU variable for workqueue congestion.  This
     slight deferral slightly increases the probability by allowing extra
     time for the workqueue to make the item requeueable.

Handle this by giving the dead state a processor function and checking the
for the dead state address rather than seeing if the processor function is
address 0x2.  The dead state processor function can then set a flag to
indicate that it's occurred and give a warning if it occurs more than once
per object.

If this race occurs, an oops similar to the following is seen (note the RIP
value):

BUG: unable to handle kernel NULL pointer dereference at 0000000000000002
IP: [<0000000000000002>] 0x1
PGD 0
Oops: 0010 [#1] SMP
Modules linked in: ...
CPU: 17 PID: 16077 Comm: kworker/u48:9 Not tainted 3.10.0-327.18.2.el7.x86_64 #1
Hardware name: HP ProLiant DL380 Gen9/ProLiant DL380 Gen9, BIOS P89 12/27/2015
Workqueue: fscache_object fscache_object_work_func [fscache]
task: ffff880302b63980 ti: ffff880717544000 task.ti: ffff880717544000
RIP: 0010:[<0000000000000002>]  [<0000000000000002>] 0x1
RSP: 0018:ffff880717547df8  EFLAGS: 00010202
RAX: ffffffffa0368640 RBX: ffff880edf7a4480 RCX: dead000000200200
RDX: 0000000000000002 RSI: 00000000ffffffff RDI: ffff880edf7a4480
RBP: ffff880717547e18 R08: 0000000000000000 R09: dfc40a25cb3a4510
R10: dfc40a25cb3a4510 R11: 0000000000000400 R12: 0000000000000000
R13: ffff880edf7a4510 R14: ffff8817f6153400 R15: 0000000000000600
FS:  0000000000000000(0000) GS:ffff88181f420000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000002 CR3: 000000000194a000 CR4: 00000000001407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Stack:
 ffffffffa0363695 ffff880edf7a4510 ffff88093f16f900 ffff8817faa4ec00
 ffff880717547e60 ffffffff8109d5db 00000000faa4ec18 0000000000000000
 ffff8817faa4ec18 ffff88093f16f930 ffff880302b63980 ffff88093f16f900
Call Trace:
 [<ffffffffa0363695>] ? fscache_object_work_func+0xa5/0x200 [fscache]
 [<ffffffff8109d5db>] process_one_work+0x17b/0x470
 [<ffffffff8109e4ac>] worker_thread+0x21c/0x400
 [<ffffffff8109e290>] ? rescuer_thread+0x400/0x400
 [<ffffffff810a5acf>] kthread+0xcf/0xe0
 [<ffffffff810a5a00>] ? kthread_create_on_node+0x140/0x140
 [<ffffffff816460d8>] ret_from_fork+0x58/0x90
 [<ffffffff810a5a00>] ? kthread_create_on_node+0x140/0x140
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Jeremy McNicoll <jeremymc@redhat.com>
Tested-by: Frank Sorenson <sorenson@redhat.com>
Tested-by: Benjamin Coddington <bcodding@redhat.com>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fscache_disable_cookie() needs to clear the outstanding writes on the
cookie it's disabling because they cannot be completed after.

Without this, fscache_nfs_open_file() gets stuck because it disables the
cookie when the file is opened for writing but can't uncache the pages till
afterwards - otherwise there's a race between the open routine and anyone
who already has it open R/O and is still reading from it.

Looking in /proc/pid/stack of the offending process shows:

[<ffffffffa0142883>] __fscache_wait_on_page_write+0x82/0x9b [fscache]
[<ffffffffa014336e>] __fscache_uncache_all_inode_pages+0x91/0xe1 [fscache]
[<ffffffffa01740fa>] nfs_fscache_open_file+0x59/0x9e [nfs]
[<ffffffffa01ccf41>] nfs4_file_open+0x17f/0x1b8 [nfsv4]
[<ffffffff8117350e>] do_dentry_open+0x16d/0x2b7
[<ffffffff811743ac>] vfs_open+0x5c/0x65
[<ffffffff81184185>] path_openat+0x785/0x8fb
[<ffffffff81184343>] do_filp_open+0x48/0x9e
[<ffffffff81174710>] do_sys_open+0x13b/0x1cb
[<ffffffff811747b9>] SyS_open+0x19/0x1b
[<ffffffff81001c44>] do_syscall_64+0x80/0x17a
[<ffffffff8165c2da>] return_from_SYSCALL_64+0x0/0x7a
[<ffffffffffffffff>] 0xffffffffffffffff
Reported-by: Jianhong Yin <jiyin@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Initialise the stores_lock in fscache netfs cookies.  Technically, it
shouldn't be necessary, since the netfs cookie is an index and stores no
data, but initialising it anyway adds insignificant overhead.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

ip6_make_flowlabel() determines the flow label for IPv6 packets. It's
supposed to be passed a flow label, which it returns as is if non-0 and
in some other cases, otherwise it calculates a new value.

The problem is callers often pass a flowi6.flowlabel, which may also
contain traffic class bits. If the traffic class is non-0
ip6_make_flowlabel() mistakes the non-0 it gets as a flow label and
returns the whole thing. Thus it can return a 'flow label' longer than
20b and the low 20b of that is typically 0 resulting in packets with 0
label. Moreover, different packets of a flow may be labeled differently.
For a TCP flow with ECN non-payload and payload packets get different
labels as exemplified by this pair of consecutive packets:

(pure ACK)
Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2::
    0110 .... = Version: 6
    .... 0000 0000 .... .... .... .... .... = Traffic Class: 0x00 (DSCP: CS0, ECN: Not-ECT)
        .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
        .... .... ..00 .... .... .... .... .... = Explicit Congestion Notification: Not ECN-Capable Transport (0)
    .... .... .... 0001 1100 1110 0100 1001 = Flow Label: 0x1ce49
    Payload Length: 32
    Next Header: TCP (6)

(payload)
Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2::
    0110 .... = Version: 6
    .... 0000 0010 .... .... .... .... .... = Traffic Class: 0x02 (DSCP: CS0, ECN: ECT(0))
        .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
        .... .... ..10 .... .... .... .... .... = Explicit Congestion Notification: ECN-Capable Transport codepoint '10' (2)
    .... .... .... 0000 0000 0000 0000 0000 = Flow Label: 0x00000
    Payload Length: 688
    Next Header: TCP (6)

This patch allows ip6_make_flowlabel() to be passed more than just a
flow label and has it extract the part it really wants. This was simpler
than modifying the callers. With this patch packets like the above become

Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2::
    0110 .... = Version: 6
    .... 0000 0000 .... .... .... .... .... = Traffic Class: 0x00 (DSCP: CS0, ECN: Not-ECT)
        .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
        .... .... ..00 .... .... .... .... .... = Explicit Congestion Notification: Not ECN-Capable Transport (0)
    .... .... .... 1010 1111 1010 0101 1110 = Flow Label: 0xafa5e
    Payload Length: 32
    Next Header: TCP (6)

Internet Protocol Version 6, Src: 2002:af5:11a3::, Dst: 2002:af5:11a2::
    0110 .... = Version: 6
    .... 0000 0010 .... .... .... .... .... = Traffic Class: 0x02 (DSCP: CS0, ECN: ECT(0))
        .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
        .... .... ..10 .... .... .... .... .... = Explicit Congestion Notification: ECN-Capable Transport codepoint '10' (2)
    .... .... .... 1010 1111 1010 0101 1110 = Flow Label: 0xafa5e
    Payload Length: 688
    Next Header: TCP (6)
Signed-off-by: Dimitris Michailidis <dmichail@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>