Instead of initializing the trap groups used by core in spectrum.c
over op, do it directly in core.c
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The call inits the EMAD group, but other groups as well. Therefore, move
it out of EMAD init code and call it before.
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Instead of calling the same code four times, do it in a loop over array
which contains trap grups to be set.
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Saeed Mahameed says:

====================
mlx5-updates-2022-01-27

1) Dima, adds an internal mlx5 steering callback per steering provider
   (FW vs SW steering), to advertise steering capabilities implemented by
   each module, this helps upper modules in mlx5 to know what is
   supported and what's not without the need to tell what is the underlying
   steering mode.
   2nd patch is the usecase where this interface is used to implement
   Vlan Push/pop for uplink with SW steering, where in FW mode it's not
   supported yet.

2) Roi Dayan improves code readability and maintainability
   as preparation step for multi attribute instance per flow
   in mlx5 TC module

   Currently the mlx5_flow object contains a single mlx5_attr instance.
   However, multi table actions (e.g. CT) instantiate multiple attr instances.

   This is a refactoring series in a preparation to support multiple
   attribute instances per flow.
   The commits prepare functions to get attr instance instead of using
   flow->attr and also using attr->flags if the flag is more relevant
   to be attr flag and not a flow flag considering there will be multiple
   attr instances. i.e. CT and SAMPLE flags.

* tag 'mlx5-updates-2022-01-27' of git://git.kernel.org/pub/scm/linux/kernel/git/saeed/linux:
  net/mlx5: VLAN push on RX, pop on TX
  net/mlx5: Introduce software defined steering capabilities
  net/mlx5: Remove unused TIR modify bitmask enums
  net/mlx5e: CT, Remove redundant flow args from tc ct calls
  net/mlx5e: TC, Store mapped tunnel id on flow attr
  net/mlx5e: Test CT and SAMPLE on flow attr
  net/mlx5e: Refactor eswitch attr flags to just attr flags
  net/mlx5e: CT, Don't set flow flag CT for ct clear flow
  net/mlx5e: TC, Hold sample_attr on stack instead of pointer
  net/mlx5e: TC, Reject rules with multiple CT actions
  net/mlx5e: TC, Refactor mlx5e_tc_add_flow_mod_hdr() to get flow attr
  net/mlx5e: TC, Pass attr to tc_act can_offload()
  net/mlx5e: TC, Split pedit offloads verify from alloc_tc_pedit_action()
  net/mlx5e: TC, Move pedit_headers_action to parse_attr
  net/mlx5e: Move counter creation call to alloc_flow_attr_counter()
  net/mlx5e: Pass attr arg for attaching/detaching encaps
  net/mlx5e: Move code chunk setting encap dests into its own function
====================

Link: https://lore.kernel.org/r/20220127204007.146300-1-saeed@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Tony Nguyen says:

====================
1GbE Intel Wired LAN Driver Updates 2022-01-27

Christophe Jaillet removes useless DMA-32 fallback calls from applicable
Intel drivers and simplifies code as a result of the removal.

* '1GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/next-queue:
  igbvf: Remove useless DMA-32 fallback configuration
  igb: Remove useless DMA-32 fallback configuration
  igc: Remove useless DMA-32 fallback configuration
  ice: Remove useless DMA-32 fallback configuration
  iavf: Remove useless DMA-32 fallback configuration
  e1000e: Remove useless DMA-32 fallback configuration
  i40e: Remove useless DMA-32 fallback configuration
  ixgbevf: Remove useless DMA-32 fallback configuration
  ixgbe: Remove useless DMA-32 fallback configuration
  ixgb: Remove useless DMA-32 fallback configuration
====================

Link: https://lore.kernel.org/r/20220127215224.422113-1-anthony.l.nguyen@intel.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

No conflicts.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Some older NIC hardware isn't capable of doing VLAN push on RX and pop
on TX.

A workaround has been added in software to support it, but it has a
performance penalty since it requires a hairpin + loopback.

There's no such limitation with the newer NICs, so no need to pay the
price of the w/a. With this change the software w/a is disabled for
certain HW versions and steering modes that support it.
Signed-off-by: Dima Chumak <dchumak@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

There are two different internal steering modes, abstracted from the
rest of the driver. In order to keep upper layer of the driver agnostic
to the differences in capabilities of the steering modes, this patch
introduces mlx5_fs_get_capabilities() API to check if a certain software
defined capability is supported. It differs from the capabilities
exposed by the hardware, as it takes into account the flow steering mode
(SMFS/DMFS) currently enabled.

This implementation supports only two capability flags:

  MLX5_FLOW_STEERING_CAP_VLAN_PUSH_ON_RX
  MLX5_FLOW_STEERING_CAP_VLAN_POP_ON_TX

They map to DR_ACTION_STATE_PUSH_VLAN and DR_ACTION_STATE_POP_VLAN
actions, implemented in SW steering earlier in commit f5e22be5
("net/mlx5: DR, Split modify VLAN state to separate pop/push states").
Which enables using of pop/push vlan without restrictions, e.g. doing
vlan pop on TX and RX, compared to FW steering that supports only vlan
pop on RX and push on TX.

Other capabilities can be added in the future.
Signed-off-by: Dima Chumak <dchumak@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Reviewed-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

struct mlx5_ifc_modify_tir_bitmask_bits is used for the bitmask
of MODIFY_TIR operations.
Remove the unused bitmask enums.
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Gal Pressman <gal@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

The flow arg is not being used so remove it.
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

In preparation for multiple attr instances the tunnel_id should
be attr specific and not flow specific.
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Currently the mlx5_flow object contains a single mlx5_attr instance.
However, multi table actions (e.g. CT) instantiate multiple attr instances.
Prepare for multiple attr instances by testing for CT or SAMPLE flag on attr
flags instead of flow flag.
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Reviewed-by: Chris Mi <cmi@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

The flags are flow attrs and not esw specific attr flags.
Refactor to remove the esw prefix and move from eswitch.h
to en_tc.h where struct mlx5_flow_attr exists.
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Reviewed-by: Vlad Buslov <vladbu@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

ct clear action is a normal flow with a modify header for registers to
0. there is no need for any special handling in tc_ct.c.
Parsing of ct clear action still allocates mod acts to set 0 on the
registers and the driver continue to add a normal rule with modify hdr
context.
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

In later commit we are going to instantiate multiple attr instances
for flow instead of single attr.
Parsing TC sample allocates a new memory but there is no symmetric
cleanup in the infrastructure.
To avoid asymmetric alloc/free use sample_attr as part of the flow attr
and not allocated and held as a pointer.
This will avoid a cleanup leak when sample action is not on the first
attr.
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

The driver doesn't support multiple CT actions.
Multiple CT clear actions are ok as they are redundant also with
another CT actions.
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

In later commit we are going to instantiate multiple attr instances
for flow instead of single attr.
Make sure mlx5e_tc_add_flow_mod_hdr() use the correct attr and not flow->attr.
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

In later commit we are going to instantiate multiple attr instances
for flow instead of single attr.
Make sure the parsing using correct attr and not flow->attr.
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Split pedit verify part into a new subfunction for better
maintainability.
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Reviewed-by: Maor Dickman <maord@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Move pedit_headers_action from flow parse_state to flow parse_attr.
In a follow up commit we are going to have multiple attr per flow
and pedit_headers_action are unique per attr.
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Reviewed-by: Maor Dickman <maord@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Move shared code to alloc_flow_attr_counter() for reuse by the next patches.
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

In later commit that we will have multiple attr instances per flow
we would like to pass a specific attr instance to set encaps.

Currently the mlx5_flow object contains a single mlx5_attr instance.
However, multi table actions (e.g. CT) instantiate multiple attr instances.

Currently mlx5e_attach/detach_encap() reads the first attr instance
from the flow instance. Modify the functions to receive the attr
instance as a parameter which is set by the calling function.
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Split setting encap dests code chunk out of mlx5e_tc_add_fdb_flow()
to make the function smaller for maintainability and reuse.
For symmetry do the same for mlx5e_tc_del_fdb_flow().
While at it refactor cleanup to first check for encap flag like
done when setting encap dests.
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Pull networking fixes from Jakub Kicinski:
 "Including fixes from netfilter and can.

  Current release - new code bugs:

   - tcp: add a missing sk_defer_free_flush() in tcp_splice_read()

   - tcp: add a stub for sk_defer_free_flush(), fix CONFIG_INET=n

   - nf_tables: set last expression in register tracking area

   - nft_connlimit: fix memleak if nf_ct_netns_get() fails

   - mptcp: fix removing ids bitmap setting

   - bonding: use rcu_dereference_rtnl when getting active slave

   - fix three cases of sleep in atomic context in drivers: lan966x, gve

   - handful of build fixes for esoteric drivers after netdev->dev_addr
     was made const

  Previous releases - regressions:

   - revert "ipv6: Honor all IPv6 PIO Valid Lifetime values", it broke
     Linux compatibility with USGv6 tests

   - procfs: show net device bound packet types

   - ipv4: fix ip option filtering for locally generated fragments

   - phy: broadcom: hook up soft_reset for BCM54616S

  Previous releases - always broken:

   - ipv4: raw: lock the socket in raw_bind()

   - ipv4: decrease the use of shared IPID generator to decrease the
     chance of attackers guessing the values

   - procfs: fix cross-netns information leakage in /proc/net/ptype

   - ethtool: fix link extended state for big endian

   - bridge: vlan: fix single net device option dumping

   - ping: fix the sk_bound_dev_if match in ping_lookup"

* tag 'net-5.17-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (86 commits)
  net: bridge: vlan: fix memory leak in __allowed_ingress
  net: socket: rename SKB_DROP_REASON_SOCKET_FILTER
  ipv4: remove sparse error in ip_neigh_gw4()
  ipv4: avoid using shared IP generator for connected sockets
  ipv4: tcp: send zero IPID in SYNACK messages
  ipv4: raw: lock the socket in raw_bind()
  MAINTAINERS: add missing IPv4/IPv6 header paths
  MAINTAINERS: add more files to eth PHY
  net: stmmac: dwmac-sun8i: use return val of readl_poll_timeout()
  net: bridge: vlan: fix single net device option dumping
  net: stmmac: skip only stmmac_ptp_register when resume from suspend
  net: stmmac: configure PTP clock source prior to PTP initialization
  Revert "ipv6: Honor all IPv6 PIO Valid Lifetime values"
  connector/cn_proc: Use task_is_in_init_pid_ns()
  pid: Introduce helper task_is_in_init_pid_ns()
  gve: Fix GFP flags when allocing pages
  net: lan966x: Fix sleep in atomic context when updating MAC table
  net: lan966x: Fix sleep in atomic context when injecting frames
  ethernet: seeq/ether3: don't write directly to netdev->dev_addr
  ethernet: 8390/etherh: don't write directly to netdev->dev_addr
  ...

When using per-vlan state, if vlan snooping and stats are disabled,
untagged or priority-tagged ingress frame will go to check pvid state.
If the port state is forwarding and the pvid state is not
learning/forwarding, untagged or priority-tagged frame will be dropped
but skb memory is not freed.
Should free skb when __allowed_ingress returns false.

Fixes: a580c76d ("net: bridge: vlan: add per-vlan state")
Signed-off-by: Tim Yi <tim.yi@pica8.com>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Link: https://lore.kernel.org/r/20220127074953.12632-1-tim.yi@pica8.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

As stated in [1], dma_set_mask() with a 64-bit mask never fails if
dev->dma_mask is non-NULL.
So, if it fails, the 32 bits case will also fail for the same reason.

So, if dma_set_mask_and_coherent() succeeds, 'pci_using_dac' is known to be
1.

Simplify code and remove some dead code accordingly.

[1]: https://lkml.org/lkml/2021/6/7/398Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

As stated in [1], dma_set_mask() with a 64-bit mask never fails if
dev->dma_mask is non-NULL.
So, if it fails, the 32 bits case will also fail for the same reason.

So, if dma_set_mask_and_coherent() succeeds, 'pci_using_dac' is known to be
1.

Simplify code and remove some dead code accordingly.

[1]: https://lkml.org/lkml/2021/6/7/398Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Tested-by: Gurucharan G <gurucharanx.g@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

As stated in [1], dma_set_mask() with a 64-bit mask never fails if
dev->dma_mask is non-NULL.
So, if it fails, the 32 bits case will also fail for the same reason.

So, if dma_set_mask_and_coherent() succeeds, 'pci_using_dac' is known to be
1.

Simplify code and remove some dead code accordingly.

[1]: https://lkml.org/lkml/2021/6/7/398Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

As stated in [1], dma_set_mask() with a 64-bit mask never fails if
dev->dma_mask is non-NULL.
So, if it fails, the 32 bits case will also fail for the same reason.

Simplify code and remove some dead code accordingly.

[1]: https://lkml.org/lkml/2021/6/7/398Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

As stated in [1], dma_set_mask() with a 64-bit mask never fails if
dev->dma_mask is non-NULL.
So, if it fails, the 32 bits case will also fail for the same reason.

Simplify code and remove some dead code accordingly.

[1]: https://lkml.org/lkml/2021/6/7/398Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

As stated in [1], dma_set_mask() with a 64-bit mask never fails if
dev->dma_mask is non-NULL.
So, if it fails, the 32 bits case will also fail for the same reason.

So, if dma_set_mask_and_coherent() succeeds, 'pci_using_dac' is known to be
1.

Simplify code and remove some dead code accordingly.

[1]: https://lkml.org/lkml/2021/6/7/398Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

As stated in [1], dma_set_mask() with a 64-bit mask never fails if
dev->dma_mask is non-NULL.
So, if it fails, the 32 bits case will also fail for the same reason.

Simplify code and remove some dead code accordingly.

[1]: https://lkml.org/lkml/2021/6/7/398Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

As stated in [1], dma_set_mask() with a 64-bit mask never fails if
dev->dma_mask is non-NULL.
So, if it fails, the 32 bits case will also fail for the same reason.

So, if dma_set_mask_and_coherent() succeeds, 'pci_using_dac' is known to be
1.

Simplify code and remove some dead code accordingly.

[1]: https://lkml.org/lkml/2021/6/7/398Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

As stated in [1], dma_set_mask() with a 64-bit mask never fails if
dev->dma_mask is non-NULL.
So, if it fails, the 32 bits case will also fail for the same reason.

So, if dma_set_mask_and_coherent() succeeds, 'pci_using_dac' is known to be
1.

Simplify code and remove some dead code accordingly.

[1]: https://lkml.org/lkml/2021/6/7/398Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

As stated in [1], dma_set_mask() with a 64-bit mask never fails if
dev->dma_mask is non-NULL.
So, if it fails, the 32 bits case will also fail for the same reason.

So, if dma_set_mask_and_coherent() succeeds, 'pci_using_dac' is known to be
1.

Simplify code and remove some dead code accordingly.

[1]: https://lkml.org/lkml/2021/6/7/398Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

Rename SKB_DROP_REASON_SOCKET_FILTER, which is used
as the reason of skb drop out of socket filter before
it's part of a released kernel. It will be used for
more protocols than just TCP in future series.
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/all/20220127091308.91401-2-imagedong@tencent.com/Signed-off-by: Jakub Kicinski <kuba@kernel.org>

./include/net/route.h:373:48: warning: incorrect type in argument 2 (different base types)
./include/net/route.h:373:48:    expected unsigned int [usertype] key
./include/net/route.h:373:48:    got restricted __be32 [usertype] daddr

Fixes: 5c9f7c1d ("ipv4: Add helpers for neigh lookup for nexthop")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20220127013404.1279313-1-eric.dumazet@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Eric Dumazet says:

====================
ipv4: less uses of shared IP generator

From: Eric Dumazet <edumazet@google.com>

We keep receiving research reports based on linux IPID generation.

Before breaking part of the Internet by switching to pure
random generator, this series reduces the need for the
shared IP generator for TCP sockets.
====================

Link: https://lore.kernel.org/r/20220127011022.1274803-1-eric.dumazet@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

ip_select_ident_segs() has been very conservative about using
the connected socket private generator only for packets with IP_DF
set, claiming it was needed for some VJ compression implementations.

As mentioned in this referenced document, this can be abused.
(Ref: Off-Path TCP Exploits of the Mixed IPID Assignment)

Before switching to pure random IPID generation and possibly hurt
some workloads, lets use the private inet socket generator.

Not only this will remove one vulnerability, this will also
improve performance of TCP flows using pmtudisc==IP_PMTUDISC_DONT

Fixes: 73f156a6 ("inetpeer: get rid of ip_id_count")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reported-by: Ray Che <xijiache@gmail.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

In commit 431280ee ("ipv4: tcp: send zero IPID for RST and
ACK sent in SYN-RECV and TIME-WAIT state") we took care of some
ctl packets sent by TCP.

It turns out we need to use a similar strategy for SYNACK packets.

By default, they carry IP_DF and IPID==0, but there are ways
to ask them to use the hashed IP ident generator and thus
be used to build off-path attacks.
(Ref: Off-Path TCP Exploits of the Mixed IPID Assignment)

One of this way is to force (before listener is started)
echo 1 >/proc/sys/net/ipv4/ip_no_pmtu_disc

Another way is using forged ICMP ICMP_FRAG_NEEDED
with a very small MTU (like 68) to force a false return from
ip_dont_fragment()

In this patch, ip_build_and_send_pkt() uses the following
heuristics.

1) Most SYNACK packets are smaller than IPV4_MIN_MTU and therefore
can use IP_DF regardless of the listener or route pmtu setting.

2) In case the SYNACK packet is bigger than IPV4_MIN_MTU,
we use prandom_u32() generator instead of the IPv4 hashed ident one.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Ray Che <xijiache@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Cc: Geoff Alexander <alexandg@cs.unm.edu>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>