When pppol2tp_session_ioctl() is called by pppol2tp_tunnel_ioctl(),
the session may be unconnected. That is, it was created by
pppol2tp_session_create() and hasn't been connected with
pppol2tp_connect(). In this case, ps->sock is NULL, so we need to check
for this case in order to avoid dereferencing a NULL pointer.

Fixes: 309795f4 ("l2tp: Add netlink control API for L2TP")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

The DMA reset timeout, used in read_poll_timeout, is
ten times shorter than the sleep time.
This patch fixes these values interchanging them, as it was
before the read_poll_timeout introduction.

Fixes: 8a70aeca ("net: stmmac: Use readl_poll_timeout")
Signed-off-by: Emiliano Ingrassia <ingrassia@epigenesys.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

While experimenting with changes to the timekeeping code, I
ran into a build error in the liquidio driver:

drivers/net/ethernet/cavium/liquidio/lio_main.c: In function 'liquidio_ptp_settime':
drivers/net/ethernet/cavium/liquidio/lio_main.c:1850:22: error: passing argument 1 of 'timespec_to_ns' from incompatible pointer type [-Werror=incompatible-pointer-types]

The driver had a type mismatch since it was first merged, but
this never caused problems because it is only built on 64-bit
architectures that define timespec and timespec64 to the same
type.

If we ever want to compile-test the driver on 32-bit or change
the way that 64-bit timespec64 is defined, we need to fix it,
so let's just do it now.

Fixes: f21fb3ed ("Add support of Cavium Liquidio ethernet adapters")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Felix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Merge tag 'wireless-drivers-for-davem-2017-10-13' of git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/wireless-drivers

Kalle Valo says:

====================
wireless-drivers fixes for 4.14

Nothing really special standing out, all of these are important fixes
which should go to 4.14.

iwlwifi

* fix support for 3168 device series

* fix a potential crash when using FW debugging recording;

* improve channel flags parsing to avoid warnings on too long traces

* return -ENODATA when the temperature is not available, since the
 -EIO we were returning was causing fatal errors in userspace

* avoid printing too many messages in dmesg when using monitor mode,
  since this can become very noisy and completely flood the logs

brcmsmac

* reduce stack usage to avoid frame size warnings with KASAN

brcmfmac

* add a check to avoid copying uninitialised memory

rtlwifi:

* fix a regression with rtl8821ae starting from v4.11 where
  connections was frequently lost
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

The kernel config help for policy routing was still pointing at
an ancient document from 2000 that refers to Linux 2.1. Update it
to point to something that is at least occasionally updated.
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Currently we drop any new VLAN ids if there are more than the current
(or last used) channel can support. Most importantly this is a problem
if no channel has been selected yet, resulting in a segfault.

Secondly this does not necessarily reflect the capabilities of any other
channels. Instead only drop a new VLAN id if we are already tracking the
maximum allowed by the NCSI specification. Per-channel limits are
already handled by ncsi_add_filter(), but add a message to set_one_vid()
to make it obvious that the channel can not support any more VLAN ids.
Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

rtl_init_one() currently enables PCI wakeups if the ethernet device
is found to be WOL-capable. There is no need to do this when
rtl8169_set_wol() will correctly enable or disable the same wakeup flag
when WOL is activated/deactivated.

This works around an ACPI DSDT bug which prevents the Acer laptop models
Aspire ES1-533, Aspire ES1-732, PackardBell ENTE69AP and Gateway NE533
from entering S3 suspend - even when no ethernet cable is connected.

On these platforms, the DSDT says that GPE08 is a wakeup source for
ethernet, but this GPE fires as soon as the system goes into suspend,
waking the system up immediately. Having the wakeup normally disabled
avoids this issue in the default case.

With this change, WOL will continue to be unusable on these platforms
(it will instantly wake up if WOL is later enabled by the user) but we
do not expect this to be a commonly used feature on these consumer
laptops. We have separately determined that WOL works fine without any
ACPI GPEs enabled during sleep, so a DSDT fix or override would be
possible to make WOL work.
Signed-off-by: Daniel Drake <drake@endlessm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Fixes: cda7ea69 ("macsec: check return value of skb_to_sgvec always")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

If for some reason, the newly allocated child need to be freed,
we will call cgroup_put() (via sk_free_unlock_clone()) while the
corresponding cgroup_get() was not yet done, and we will free memory
too soon.

Fixes: d979a39d ("cgroup: duplicate cgroup reference when cloning sockets")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

This reverts commit fbb1fb4a.

This was not the proper fix, lets cleanly revert it, so that
following patch can be carried to stable versions.

sock_cgroup_ptr() callers do not expect a NULL return value.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Jakub Kicinski says:

====================
nfp: fix ethtool stats and page allocation

Two fixes for net.  First one makes sure we handle gather of stats on
32bit machines correctly (ouch).  The second fix solves a potential
NULL-deref if we fail to allocate a page with XDP running.

I used Fixes: tags pointing to where the bug was introduced, but for
patch 1 it has been in the driver "for ever" and fix won't backport
cleanly beyond commit 325945ed ("nfp: split software and hardware
vNIC statistics") which is in net.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

page_address() does not handle NULL argument gracefully,
make sure we NULL-check the page pointer before passing it
to page_address().

Fixes: ecd63a02 ("nfp: add XDP support in the driver")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The while loop fetching 64 bit ethtool statistics may have
to retry multiple times, it shouldn't modify the outside state.

Fixes: 4c352362 ("net: add driver for Netronome NFP4000/NFP6000 NIC VFs")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Jeff Kirsher says:

====================
Intel Wired LAN Driver Updates 2017-10-10

This series contains updates to i40e only.

Stefano Brivio fixes the grammar in a function header comment.

Alex fixes a memory leak where we were not correctly placing the pages
from buffers that had been used to return a filter programming status
back on the ring.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Convert Variable Length Array in Struct (VLAIS) to valid C by converting
local struct definition to use a flexible array. The structure is only
used to define a cast of a buffer so the size of the struct is not used
to allocate storage.
Signed-off-by: Behan Webster <behanw@converseincode.com>
Signed-off-by: Mark Charebois <charlebm@gmail.com>
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

It looks like we weren't correctly placing the pages from buffers that had
been used to return a filter programming status back on the ring. As a
result they were being overwritten and tracking of the pages was lost.

This change works to correct that by incorporating part of
i40e_put_rx_buffer into the programming status handler code. As a result we
should now be correctly placing the pages for those buffers on the
re-allocation list instead of letting them stay in place.

Fixes: 0e626ff7 ("i40e: Fix support for flow director programming status")
Reported-by: Anders K. Pedersen <akp@cohaesio.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Anders K Pedersen <akp@cohaesio.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Caller needs to acquire the lock. Called functions will not.

Fixes: 09f79fd4 ("i40e: avoid NVM acquire deadlock during NVM update")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

sk_clone_lock() might run while TCP/DCCP listener already vanished.

In order to prevent use after free, it is better to defer cgroup_sk_alloc()
to the point we know both parent and child exist, and from process context.

Fixes: e994b2f0 ("tcp: do not lock listener to process SYN packets")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Instead of calling mem_cgroup_sk_alloc() from BH context,
it is better to call it from inet_csk_accept() in process context.

Not only this removes code in mem_cgroup_sk_alloc(), but it also
fixes a bug since listener might have been dismantled and css_get()
might cause a use-after-free.

Fixes: e994b2f0 ("tcp: do not lock listener to process SYN packets")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Merge powerpc transactional memory fixes from Michael Ellerman:
 "I figured I'd still send you the commits using a bundle to make sure
  it works in case I need to do it again in future"

This fixes transactional memory state restore for powerpc.

* bundle'd patches from Michael Ellerman:
  powerpc/tm: Fix illegal TM state in signal handler
  powerpc/64s: Use emergency stack for kernel TM Bad Thing program checks

Pull networking fixes from David Miller:

 1) Fix object leak on IPSEC offload failure, from Steffen Klassert.

 2) Fix range checks in ipset address range addition operations, from
    Jozsef Kadlecsik.

 3) Fix pernet ops unregistration order in ipset, from Florian Westphal.

 4) Add missing netlink attribute policy for nl80211 packet pattern
    attrs, from Peng Xu.

 5) Fix PPP device destruction race, from Guillaume Nault.

 6) Write marks get lost when BPF verifier processes R1=R2 register
    assignments, causing incorrect liveness information and less state
    pruning. Fix from Alexei Starovoitov.

 7) Fix blockhole routes so that they are marked dead and therefore not
    cached in sockets, otherwise IPSEC stops working. From Steffen
    Klassert.

 8) Fix broadcast handling of UDP socket early demux, from Paolo Abeni.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (37 commits)
  cdc_ether: flag the u-blox TOBY-L2 and SARA-U2 as wwan
  net: thunderx: mark expected switch fall-throughs in nicvf_main()
  udp: fix bcast packet reception
  netlink: do not set cb_running if dump's start() errs
  ipv4: Fix traffic triggered IPsec connections.
  ipv6: Fix traffic triggered IPsec connections.
  ixgbe: incorrect XDP ring accounting in ethtool tx_frame param
  net: ixgbe: Use new PCI_DEV_FLAGS_NO_RELAXED_ORDERING flag
  Revert commit 1a8b6d76 ("net:add one common config...")
  ixgbe: fix masking of bits read from IXGBE_VXLANCTRL register
  ixgbe: Return error when getting PHY address if PHY access is not supported
  netfilter: xt_bpf: Fix XT_BPF_MODE_FD_PINNED mode of 'xt_bpf_info_v1'
  netfilter: SYNPROXY: skip non-tcp packet in {ipv4, ipv6}_synproxy_hook
  tipc: Unclone message at secondary destination lookup
  tipc: correct initialization of skb list
  gso: fix payload length when gso_size is zero
  mlxsw: spectrum_router: Avoid expensive lookup during route removal
  bpf: fix liveness marking
  doc: Fix typo "8023.ad" in bonding documentation
  ipv6: fix net.ipv6.conf.all.accept_dad behaviour for real
  ...

The u-blox TOBY-L2 is a LTE Cat 4 module with HSPA+ and 2G fallback.
This module allows switching to different USB profiles with the
'AT+UUSBCONF' command, and provides a ECM network interface when the
'AT+UUSBCONF=2' profile is selected.

The u-blox SARA-U2 is a HSPA module with 2G fallback. The default USB
configuration includes a ECM network interface.

Both these modules are controlled via AT commands through one of the
TTYs exposed. Connecting these modules may be done just by activating
the desired PDP context with 'AT+CGACT=1,<cid>' and then running DHCP
on the ECM interface.
Signed-off-by: Aleksander Morgado <aleksander@aleksander.es>
Signed-off-by: David S. Miller <davem@davemloft.net>

Pull NFS client bugfixes from Trond Myklebust:
 "Hightlights include:

  stable fixes:
   - nfs/filelayout: fix oops when freeing filelayout segment
   - NFS: Fix uninitialized rpc_wait_queue

  bugfixes:
   - NFSv4/pnfs: Fix an infinite layoutget loop
   - nfs: RPC_MAX_AUTH_SIZE is in bytes"

* tag 'nfs-for-4.14-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  NFSv4/pnfs: Fix an infinite layoutget loop
  nfs/filelayout: fix oops when freeing filelayout segment
  sunrpc: remove redundant initialization of sock
  NFS: Fix uninitialized rpc_wait_queue
  NFS: Cleanup error handling in nfs_idmap_request_key()
  nfs: RPC_MAX_AUTH_SIZE is in bytes

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Cc: Sunil Goutham <sgoutham@cavium.com>
Cc: Robert Richter <rric@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: netdev@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Pablo Neira Ayuso says:

====================
Netfilter/IPVS fixes for net

The following patchset contains Netfilter/IPVS fixes for your net tree,
they are:

1) Fix packet drops due to incorrect ECN handling in IPVS, from Vadim
   Fedorenko.

2) Fix splat with mark restoration in xt_socket with non-full-sock,
   patch from Subash Abhinov Kasiviswanathan.

3) ipset bogusly bails out when adding IPv4 range containing more than
   2^31 addresses, from Jozsef Kadlecsik.

4) Incorrect pernet unregistration order in ipset, from Florian Westphal.

5) Races between dump and swap in ipset results in BUG_ON splats, from
   Ross Lagerwall.

6) Fix chain renames in nf_tables, from JingPiao Chen.

7) Fix race in pernet codepath with ebtables table registration, from
   Artem Savkov.

8) Memory leak in error path in set name allocation in nf_tables, patch
   from Arvind Yadav.

9) Don't dump chain counters if they are not available, this fixes a
   crash when listing the ruleset.

10) Fix out of bound memory read in strlcpy() in x_tables compat code,
    from Eric Dumazet.

11) Make sure we only process TCP packets in SYNPROXY hooks, patch from
    Lin Zhang.

12) Cannot load rules incrementally anymore after xt_bpf with pinned
    objects, added in revision 1. From Shmulik Ladkani.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Jeff Kirsher says:

====================
Intel Wired LAN Driver Updates 2017-10-09

This series contains updates to ixgbe and arch/Kconfig.

Mark fixes a case where PHY register access is not supported and we were
returning a PHY address, when we should have been returning -EOPNOTSUPP.

Sabrina Dubroca fixes the use of a logical "and" when it should have been
the bitwise "and" operator.

Ding Tianhong reverts the commit that added the Kconfig bool option
ARCH_WANT_RELAX_ORDER, since there is now a new flag
PCI_DEV_FLAGS_NO_RELAXED_ORDERING that has been added to indicate that
Relaxed Ordering Attributes should not be used for Transaction Layer
Packets.  Then follows up with making the needed changes to ixgbe to
use the new PCI_DEV_FLAGS_NO_RELAXED_ORDERING flag.

John Fastabend fixes an issue in the ring accounting when the transmit
ring parameters are changed via ethtool when an XDP program is attached.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

The commit bc044e8d ("udp: perform source validation for
mcast early demux") does not take into account that broadcast packets
lands in the same code path and they need different checks for the
source address - notably, zero source address are valid for bcast
and invalid for mcast.

As a result, 2nd and later broadcast packets with 0 source address
landing to the same socket are dropped. This breaks dhcp servers.

Since we don't have stringent performance requirements for ingress
broadcast traffic, fix it by disabling UDP early demux such traffic.
Reported-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Fixes: bc044e8d ("udp: perform source validation for mcast early demux")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

It turns out that multiple places can call netlink_dump(), which means
it's still possible to dereference partially initialized values in
dump() that were the result of a faulty returned start().

This fixes the issue by calling start() _before_ setting cb_running to
true, so that there's no chance at all of hitting the dump() function
through any indirect paths.

It also moves the call to start() to be when the mutex is held. This has
the nice side effect of serializing invocations to start(), which is
likely desirable anyway. It also prevents any possible other races that
might come out of this logic.

In testing this with several different pieces of tricky code to trigger
these issues, this commit fixes all avenues that I'm aware of.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

Merge tag 'mac80211-for-davem-2017-10-09' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211

Johannes Berg says:

====================
pull-request: mac80211 2017-10-09

The QCA folks found another netlink problem - we were missing validation
of some attributes. It's not super problematic since one can only read a
few bytes beyond the message (and that memory must exist), but here's the
fix for it.

I thought perhaps we can make nla_parse_nested() require a policy, but
given the two-stage validation/parsing in regular netlink that won't work.

Please pull and let me know if there's any problem.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Steffen Klassert says:

====================
pull request (net): ipsec 2017-10-09

1) Fix some error paths of the IPsec offloading API.

2) Fix a NULL pointer dereference when IPsec is used
   with vti. From Alexey Kodanev.

3) Don't call xfrm_policy_cache_flush under xfrm_state_lock,
   it triggers several locking warnings. From Artem Savkov.

Please pull or let me know if there are problems.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

A recent patch removed the dst_free() on the allocated
dst_entry in ipv4_blackhole_route(). The dst_free() marked the
dst_entry as dead and added it to the gc list. I.e. it was setup
for a one time usage. As a result we may now have a blackhole
route cached at a socket on some IPsec scenarios. This makes the
connection unusable.

Fix this by marking the dst_entry directly at allocation time
as 'dead', so it is used only once.

Fixes: b838d5e1 ("ipv4: mark DST_NOGC and remove the operation of dst_free()")
Reported-by: Tobias Brunner <tobias@strongswan.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

A recent patch removed the dst_free() on the allocated
dst_entry in ipv6_blackhole_route(). The dst_free() marked
the dst_entry as dead and added it to the gc list. I.e. it
was setup for a one time usage. As a result we may now have
a blackhole route cached at a socket on some IPsec scenarios.
This makes the connection unusable.

Fix this by marking the dst_entry directly at allocation time
as 'dead', so it is used only once.

Fixes: 587fea74 ("ipv6: mark DST_NOGC and remove the operation of dst_free()")
Reported-by: Tobias Brunner <tobias@strongswan.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Changing the TX ring parameters with an XDP program attached may
cause the XDP queues to be cleared and the TX rings to be incorrectly
configured.

Fix by doing correct ring accounting in setup call.

Fixes: 33fdc82f ("ixgbe: add support for XDP_TX action")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

The ixgbe driver use the compile check to determine if it can
send TLPs to Root Port with the Relaxed Ordering Attribute set,
this is too inconvenient, now the new flag PCI_DEV_FLAGS_NO_RELAXED_ORDERING
has been added to the kernel and we could check the bit4 in the PCIe
Device Control register to determine whether we should use the Relaxed
Ordering Attributes or not, so use this new way in the ixgbe driver.
Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
Acked-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

The new flag PCI_DEV_FLAGS_NO_RELAXED_ORDERING has been added
to indicate that Relaxed Ordering Attributes (RO) should not
be used for Transaction Layer Packets (TLP) targeted toward
these affected Root Port, it will clear the bit4 in the PCIe
Device Control register, so the PCIe device drivers could
query PCIe configuration space to determine if it can send
TLPs to Root Port with the Relaxed Ordering Attributes set.

With this new flag  we don't need the config ARCH_WANT_RELAX_ORDER
to control the Relaxed Ordering Attributes for the ixgbe drivers
just like the commit 1a8b6d76 ("net:add one common config...") did,
so revert this commit.
Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

In ixgbe_clear_udp_tunnel_port(), we read the IXGBE_VXLANCTRL register
and then try to mask some bits out of the value, using the logical
instead of bitwise and operator.

Fixes: a21d0822 ("ixgbe: add support for geneve Rx offload")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

In cases where PHY register access is not supported, don't mislead
a caller into thinking that it is supported by returning a PHY
address. Instead, return -EOPNOTSUPP when PHY access is not
supported.
Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Merge tag 'iwlwifi-for-kalle-2017-10-06' of git://git.kernel.org/pub/scm/linux/kernel/git/iwlwifi/iwlwifi-fixes

Second set of iwlwifi fixes for 4.14

* Fix support for 3168 device series;
* Fix a potential crash when using FW debugging recording;
* Improve channel flags parsing to avoid warnings on too long traces;
* Return -ENODATA when the temperature is not available, since the
  -EIO we were returning was causing fatal errors in userspace;
* Avoid printing too many messages in dmesg when using monitor mode,
  since this can become very noisy and completely flood the logs;

Commit 2c16d603 ("netfilter: xt_bpf: support ebpf") introduced
support for attaching an eBPF object by an fd, with the
'bpf_mt_check_v1' ABI expecting the '.fd' to be specified upon each
IPT_SO_SET_REPLACE call.

However this breaks subsequent iptables calls:

 # iptables -A INPUT -m bpf --object-pinned /sys/fs/bpf/xxx -j ACCEPT
 # iptables -A INPUT -s 5.6.7.8 -j ACCEPT
 iptables: Invalid argument. Run `dmesg' for more information.

That's because iptables works by loading existing rules using
IPT_SO_GET_ENTRIES to userspace, then issuing IPT_SO_SET_REPLACE with
the replacement set.

However, the loaded 'xt_bpf_info_v1' has an arbitrary '.fd' number
(from the initial "iptables -m bpf" invocation) - so when 2nd invocation
occurs, userspace passes a bogus fd number, which leads to
'bpf_mt_check_v1' to fail.

One suggested solution [1] was to hack iptables userspace, to perform a
"entries fixup" immediatley after IPT_SO_GET_ENTRIES, by opening a new,
process-local fd per every 'xt_bpf_info_v1' entry seen.

However, in [2] both Pablo Neira Ayuso and Willem de Bruijn suggested to
depricate the xt_bpf_info_v1 ABI dealing with pinned ebpf objects.

This fix changes the XT_BPF_MODE_FD_PINNED behavior to ignore the given
'.fd' and instead perform an in-kernel lookup for the bpf object given
the provided '.path'.

It also defines an alias for the XT_BPF_MODE_FD_PINNED mode, named
XT_BPF_MODE_PATH_PINNED, to better reflect the fact that the user is
expected to provide the path of the pinned object.

Existing XT_BPF_MODE_FD_ELF behavior (non-pinned fd mode) is preserved.

References: [1] https://marc.info/?l=netfilter-devel&m=150564724607440&w=2
            [2] https://marc.info/?l=netfilter-devel&m=150575727129880&w=2Reported-by: Rafael Buchbinder <rafi@rbk.ms>
Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>