When tls_sw_recvmsg() partially copies a record it pops that
record from ctx->recv_pkt and places it on rx_list.

Next iteration of tls_sw_recvmsg() reads from rx_list via
process_rx_list() before it enters the decryption loop.
If there is no more records to be read tls_wait_data()
will put the process on the wait queue and got to sleep.
This is incorrect, because some data was already copied
in process_rx_list().

In case of RPC connections process may never get woken up,
because peer also simply blocks in read().

I think this may also fix a similar issue when BPF is at
play, because after __tcp_bpf_recvmsg() returns some data
we subtract it from len and use continue to restart the
loop, but len could have just reached 0, so again we'd
sleep unnecessarily. That's added by:
commit d3b18ad3 ("tls: add bpf support to sk_msg handling")

Fixes: 692d7b5d ("tls: Fix recvmsg() to be able to peek across multiple records")
Reported-by: NDavid Beckett <david.beckett@netronome.com>
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NDirk van der Merwe <dirk.vandermerwe@netronome.com>
Tested-by: NDavid Beckett <david.beckett@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Set SO_RCVLOWAT and test it gets respected when gathering
data from multiple records.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NDirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If some of the data came from the previous record, i.e. from
the rx_list it had already been decrypted, so it's not counted
towards the "decrypted" variable, but the "copied" variable.
Take that into account when checking lowat.

When calculating lowat target we need to pass the original len.
E.g. if lowat is at 80, len is 100 and we had 30 bytes on rx_list
target would currently be incorrectly calculated as 70, even though
we only need 50 more bytes to make up the 80.

Fixes: 692d7b5d ("tls: Fix recvmsg() to be able to peek across multiple records")
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NDirk van der Merwe <dirk.vandermerwe@netronome.com>
Tested-by: NDavid Beckett <david.beckett@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Ioana Radulescu says:

====================
dpaa2-eth: Fix smatch warnings

Fix a couple of warnings reported by smatch.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Function dpaa2_eth_cls_key_size() expects a 64bit argument,
but DPAA2_ETH_DIST_ALL is defined as UINT_MAX. Fix this.
Signed-off-by: NIoana Radulescu <ruxandra.radulescu@nxp.com>
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use PTR_ERR_OR_ZERO instead of PTR_ERR in cases where
zero is a valid input. Reported by smatch.
Signed-off-by: NIoana Radulescu <ruxandra.radulescu@nxp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Smatch reports a potential spectre vulnerability in the dpaa2-eth
driver, where the value of rxnfc->fs.location (which is provided
from user-space) is used as index in an array.

Add a call to array_index_nospec() to sanitize the access.
Signed-off-by: NIoana Radulescu <ruxandra.radulescu@nxp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Once in a while, with just the right timing, 802.3ad slaves will fail to
properly initialize, winding up in a weird state, with a partner system
mac address of 00:00:00:00:00:00. This started happening after a fix to
properly track link_failure_count tracking, where an 802.3ad slave that
reported itself as link up in the miimon code, but wasn't able to get a
valid speed/duplex, started getting set to BOND_LINK_FAIL instead of
BOND_LINK_DOWN. That was the proper thing to do for the general "my link
went down" case, but has created a link initialization race that can put
the interface in this odd state.

The simple fix is to instead set the slave link to BOND_LINK_DOWN again,
if the link has never been up (last_link_up == 0), so the link state
doesn't bounce from BOND_LINK_DOWN to BOND_LINK_FAIL -- it hasn't failed
in this case, it simply hasn't been up yet, and this prevents the
unnecessary state change from DOWN to FAIL and getting stuck in an init
failure w/o a partner mac.

Fixes: ea53abfa ("bonding/802.3ad: fix link_failure_count tracking")
CC: Jay Vosburgh <j.vosburgh@gmail.com>
CC: Veaceslav Falico <vfalico@gmail.com>
CC: Andy Gospodarek <andy@greyhouse.net>
CC: "David S. Miller" <davem@davemloft.net>
CC: netdev@vger.kernel.org
Tested-by: NHeesoon Kim <Heesoon.Kim@stratus.com>
Signed-off-by: NJarod Wilson <jarod@redhat.com>
Acked-by: NJay Vosburgh <jay.vosburgh@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

ethtool ops get_rxfh_context and set_rxfh_context are used to create,
remove and access parameters associated to RSS contexts, in a similar
fashion to get_rxfh and set_rxfh.

Add a small descritopn of these callbacks in the struct ethtool_ops doc.
Signed-off-by: NMaxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Biao Huang says:

====================
fix some bugs in stmmac

changes in v4:
        since MTL_OPERATION_MODE write back issue has be fixed in the latest driver,
remove original patch#3

changes in v3:
        add a Fixes:tag for each patch

changes in v2:
        1. update rx_tail_addr as Jose's comment
        2. changes clk_csr condition as Alex's proposition
        3. remove init lines in dwmac-mediatek, get clk_csr from dts instead.

v1:
This series fix some bugs in stmmac driver
3 patches are for common stmmac or dwmac4:
        1. update rx tail pointer to fix rx dma hang issue.
        2. change condition for mdc clock to fix csr_clk can't be zero issue.
        3. write the modified value back to MTL_OPERATION_MODE.
1 patch is for dwmac-mediatek:
        modify csr_clk value to fix mdio read/write fail issue for dwmac-mediatek
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

1. the frequency of csr clock is 66.5MHz, so the csr_clk value should
be 0 other than 5.
2. the csr_clk can be got from device tree, so remove initialization here.

Fixes: 9992f37e ("stmmac: dwmac-mediatek: add support for mt2712")
Signed-off-by: NBiao Huang <biao.huang@mediatek.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The specific clk_csr value can be zero, and
stmmac_clk is necessary for MDC clock which can be set dynamically.
So, change the condition from plat->clk_csr to plat->stmmac_clk to
fix clk_csr can't be zero issue.

Fixes: cd7201f4 ("stmmac: MDC clock dynamically based on the csr clock input")
Signed-off-by: NBiao Huang <biao.huang@mediatek.com>
Acked-by: NAlexandre TORGUE <alexandre.torgue@st.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently we will not update the receive descriptor tail pointer in
stmmac_rx_refill. Rx dma will think no available descriptors and stop
once received packets exceed DMA_RX_SIZE, so that the rx only test will fail.

Update the receive tail pointer in stmmac_rx_refill to add more descriptors
to the rx channel, so packets can be received continually

Fixes: 54139cf3 ("net: stmmac: adding multiple buffers for rx")
Signed-off-by: NBiao Huang <biao.huang@mediatek.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In function ip_ra_control(), the pointer new_ra is allocated a memory
space via kmalloc(). And it is used in the following codes. However,
when  there is a memory allocation error, kmalloc() fails. Thus null
pointer dereference may happen. And it will cause the kernel to crash.
Therefore, we should check the return value and handle the error.
Signed-off-by: NGen Zhang <blackgod016574@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In function ip6_ra_control(), the pointer new_ra is allocated a memory
space via kmalloc(). And it is used in the following codes. However,
when there is a memory allocation error, kmalloc() fails. Thus null
pointer dereference may happen. And it will cause the kernel to crash.
Therefore, we should check the return value and handle the error.
Signed-off-by: NGen Zhang <blackgod016574@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Function tcf_action_dump() relies on tc_action->order field when starting
nested nla to send action data to userspace. This approach breaks in
several cases:

- When multiple filters point to same shared action, tc_action->order field
  is overwritten each time it is attached to filter. This causes filter
  dump to output action with incorrect attribute for all filters that have
  the action in different position (different order) from the last set
  tc_action->order value.

- When action data is displayed using tc action API (RTM_GETACTION), action
  order is overwritten by tca_action_gd() according to its position in
  resulting array of nl attributes, which will break filter dump for all
  filters attached to that shared action that expect it to have different
  order value.

Don't rely on tc_action->order when dumping actions. Set nla according to
action position in resulting array of actions instead.
Signed-off-by: NVlad Buslov <vladbu@mellanox.com>
Acked-by: NJamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This reverts commit 2391b003 which has
introduced regression. Now SGE's BAR2 Doorbell/GTS Page Size is
interpreted correctly in the firmware itself by using actual host
page size. Hence previous commit needs to be reverted.
Signed-off-by: NVishal Kulkarni <vishal@chelsio.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fix the clk mismatch in the error path "failed_reset" because
below error path will disable clk_ahb and clk_ipg directly, it
should use pm_runtime_put_noidle() instead of pm_runtime_put()
to avoid to call runtime resume callback.
Reported-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NFugang Duan <fugang.duan@nxp.com>
Tested-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NDavid 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:

1) Fix crash when dumping rules after conversion to RCU,
   from Florian Westphal.

2) Fix incorrect hook reinjection from nf_queue in case NF_REPEAT,
   from Jagdish Motwani.

3) Fix check for route existence in fib extension, from Phil Sutter.

4) Fix use after free in ip_vs_in() hook, from YueHaibing.

5) Check for veth existence from netfilter selftests,
   from Jeffrin Jose T.

6) Checksum corruption in UDP NAT helpers due to typo,
   from Florian Westphal.

7) Pass up packets to classic forwarding path regardless of
   IPv4 DF bit, patch for the flowtable infrastructure from Florian.

8) Set liberal TCP tracking for flows that are placed in the
   flowtable, in case they need to go back to classic forwarding path,
   also from Florian.

9) Don't add flow with sequence adjustment to flowtable, from Florian.

10) Skip IPv4 options from IPv6 datapath in flowtable, from Florian.

11) Add selftest for the flowtable infrastructure, from Florian.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

VLAN flows never get offloaded unless ivlan_vld is set in filter spec.
It's not compulsory for vlan_ethtype to be set.

So, always enable ivlan_vld bit for offloading VLAN flows regardless of
vlan_ethtype is set or not.

Fixes: ad9af3e0 (cxgb4: add tc flower match support for vlan)
Signed-off-by: NRaju Rangoju <rajur@chelsio.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Don't prune the master node in the hsr_prune_nodes function.
Neither time_in[HSR_PT_SLAVE_A] nor time_in[HSR_PT_SLAVE_B]
will ever be updated by hsr_register_frame_in for the master port.
Thus, the master node will be repeatedly pruned leading to
repeated packet loss.
This bug never appeared because the hsr_prune_nodes function
was only called once. Since commit 5150b45f
("net: hsr: Fix node prune function for forget time expiry") this issue
is fixed unveiling the issue described above.

Fixes: 5150b45f ("net: hsr: Fix node prune function for forget time expiry")
Signed-off-by: NAndreas Oetken <andreas.oetken@siemens.com>
Tested-by: NMurali Karicheri <m-karicheri2@ti.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The flow_rule is only used when configuring the classification tables,
and should be free'd once we're done using it. The current code only
frees it in the error path.

Fixes: 90b509b3 ("net: mvpp2: cls: Add Classification offload support")
Signed-off-by: NMaxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

ip_sf_list_clear_all() needs to be defined even if !CONFIG_IP_MULTICAST

Fixes: 3580d04a ("ipv4/igmp: fix another memory leak in igmpv3_del_delrec()")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: Nkbuild test robot <lkp@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

syzbot reported memory leaks [1] that I have back tracked to
a missing cleanup from igmpv3_del_delrec() when
(im->sfmode != MCAST_INCLUDE)

Add ip_sf_list_clear_all() and kfree_pmc() helpers to explicitely
handle the cleanups before freeing.

[1]

BUG: memory leak
unreferenced object 0xffff888123e32b00 (size 64):
  comm "softirq", pid 0, jiffies 4294942968 (age 8.010s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 e0 00 00 01 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<000000006105011b>] kmemleak_alloc_recursive include/linux/kmemleak.h:55 [inline]
    [<000000006105011b>] slab_post_alloc_hook mm/slab.h:439 [inline]
    [<000000006105011b>] slab_alloc mm/slab.c:3326 [inline]
    [<000000006105011b>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553
    [<000000004bba8073>] kmalloc include/linux/slab.h:547 [inline]
    [<000000004bba8073>] kzalloc include/linux/slab.h:742 [inline]
    [<000000004bba8073>] ip_mc_add1_src net/ipv4/igmp.c:1961 [inline]
    [<000000004bba8073>] ip_mc_add_src+0x36b/0x400 net/ipv4/igmp.c:2085
    [<00000000a46a65a0>] ip_mc_msfilter+0x22d/0x310 net/ipv4/igmp.c:2475
    [<000000005956ca89>] do_ip_setsockopt.isra.0+0x1795/0x1930 net/ipv4/ip_sockglue.c:957
    [<00000000848e2d2f>] ip_setsockopt+0x3b/0xb0 net/ipv4/ip_sockglue.c:1246
    [<00000000b9db185c>] udp_setsockopt+0x4e/0x90 net/ipv4/udp.c:2616
    [<000000003028e438>] sock_common_setsockopt+0x38/0x50 net/core/sock.c:3130
    [<0000000015b65589>] __sys_setsockopt+0x98/0x120 net/socket.c:2078
    [<00000000ac198ef0>] __do_sys_setsockopt net/socket.c:2089 [inline]
    [<00000000ac198ef0>] __se_sys_setsockopt net/socket.c:2086 [inline]
    [<00000000ac198ef0>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2086
    [<000000000a770437>] do_syscall_64+0x76/0x1a0 arch/x86/entry/common.c:301
    [<00000000d3adb93b>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: 9c8bb163 ("igmp, mld: Fix memory leak in igmpv3/mld_del_delrec()")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Hangbin Liu <liuhangbin@gmail.com>
Reported-by: Nsyzbot <syzkaller@googlegroups.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Michael Chan says:

===================
bnxt_en: Bug fixes.

There are 4 driver fixes in this series:

1. Fix RX buffer leak during OOM condition.
2. Call pci_disable_msix() under correct conditions to prevent hitting BUG.
3. Reduce unneeded mmeory allocation in kdump kernel to prevent OOM.
4. Don't read device serial number on VFs because it is not supported.

Please queue #1, #2, #3 for -stable as well.  Thanks.
===================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Don't read DSN on VFs that do not have the PCI capability.

Fixes: 03213a99 ("bnxt: move bp->switch_id initialization to PF probe")
Signed-off-by: NVasundhara Volam <vasundhara-v.volam@broadcom.com>
Signed-off-by: NMichael Chan <michael.chan@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Skip RDMA context memory allocations, reduce to 1 ring, and disable
TPA when running in the kdump kernel.  Without this patch, the driver
fails to initialize with memory allocation errors when running in a
typical kdump kernel.

Fixes: cf6daed0 ("bnxt_en: Increase context memory allocations on 57500 chips for RDMA.")
Signed-off-by: NMichael Chan <michael.chan@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When making configuration changes, the driver calls bnxt_close_nic()
and then bnxt_open_nic() for the changes to take effect.  A parameter
irq_re_init is passed to the call sequence to indicate if IRQ
should be re-initialized.  This irq_re_init parameter needs to
be included in the bnxt_reserve_rings() call.  bnxt_reserve_rings()
can only call pci_disable_msix() if the irq_re_init parameter is
true, otherwise it may hit BUG() because some IRQs may not have been
freed yet.

Fixes: 41e8d798 ("bnxt_en: Modify the ring reservation functions for 57500 series chips.")
Signed-off-by: NMichael Chan <michael.chan@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

For every RX packet, the driver replenishes all buffers used for that
packet and puts them back into the RX ring and RX aggregation ring.
In one code path where the RX packet has one RX buffer and one or more
aggregation buffers, we missed recycling the aggregation buffer(s) if
we are unable to allocate a new SKB buffer.  This leads to the
aggregation ring slowly running out of buffers over time.  Fix it
by properly recycling the aggregation buffers.

Fixes: c0c050c5 ("bnxt_en: New Broadcom ethernet driver.")
Reported-by: NRakesh Hemnani <rhemnani@fb.com>
Signed-off-by: NMichael Chan <michael.chan@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

IPv6 redirect is broken for VRF. __ip6_route_redirect walks the FIB
entries looking for an exact match on ifindex. With VRF the flowi6_oif
is updated by l3mdev_update_flow to the l3mdev index and the
FLOWI_FLAG_SKIP_NH_OIF set in the flags to tell the lookup to skip the
device match. For redirects the device match is requires so use that
flag to know when the oif needs to be reset to the skb device index.

Fixes: ca254490 ("net: Add VRF support to IPv6 stack")
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Commit 984203ce ("net: stmmac: mdio: remove reset gpio free")
removed the reset gpio free, when the driver is unbinded or rmmod,
we miss the gpio free.

This patch uses managed API to request the reset gpio, so that the
gpio could be freed properly.

Fixes: 984203ce ("net: stmmac: mdio: remove reset gpio free")
Signed-off-by: NJisheng Zhang <Jisheng.Zhang@synaptics.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The user can change the device_name with the IMSETDEVNAME ioctl, but we
need to ensure that the user's name is NUL terminated.  Otherwise it
could result in a buffer overflow when we copy the name back to the user
with IMGETDEVINFO ioctl.

I also changed two strcpy() calls which handle the name to strscpy().
Hopefully, there aren't any other ways to create a too long name, but
it's nice to do this as a kernel hardening measure.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

SAMA5D2 SoC has a suspend mode where SoC's power is cut off. Due to this
the registers content is lost after a suspend/resume cycle. The current
suspend/resume implementation covers some of these registers. However
there are few which were not treated (e.g. SCRT2 and USRIO). Apart
from this, netdev features are not restored. Treat these issues.
Signed-off-by: NClaudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Jakub Kicinski says:

====================
net/tls: fix device surprise removal with offload

This series fixes two issues with device surprise removal.
First we need to take a read lock around resync, otherwise
netdev notifier handler may clear the structures from under
our feet.

Secondly we need to be careful about the interpretation
of device features.  Offload has to be properly cleaned
up even if the TLS device features got cleared after
connection state was installed.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

On device surprise removal path (the notifier) we can't
bail just because the features are disabled.  They may
have been enabled during the lifetime of the device.
This bug leads to leaking netdev references and
use-after-frees if there are active connections while
device features are cleared.

Fixes: e8f69799 ("net/tls: Add generic NIC offload infrastructure")
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NDirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

TLS offload drivers shouldn't (and currently don't) block
the TLS offload feature changes based on whether there are
active offloaded connections or not.

This seems to be a good idea, because we want the admin to
be able to disable the TLS offload at any time, and there
is no clean way of disabling it for active connections
(TX side is quite problematic).  So if features are cleared
existing connections will stay offloaded until they close,
and new connections will not attempt offload to a given
device.

However, the offload state removal handling is currently
broken if feature flags get cleared while there are
active TLS offloads.

RX side will completely bail from cleanup, even on normal
remove path, leaving device state dangling, potentially
causing issues when the 5-tuple is reused.  It will also
fail to release the netdev reference.

Remove the RX-side warning message, in next release cycle
it should be printed when features are disabled, rather
than when connection dies, but for that we need a more
efficient method of finding connection of a given netdev
(a'la BPF offload code).

Fixes: 4799ac81 ("tls: Add rx inline crypto offload")
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NDirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When netdev with active kTLS sockets in unregistered
notifier callback walks the offloaded sockets and
cleans up offload state.  RX data may still be processed,
however, and if resync was requested prior to device
removal we would hit a NULL pointer dereference on
ctx->netdev use.

Make sure resync is under the device offload lock
and NULL-check the netdev pointer.

This should be safe, because the pointer is set to
NULL either in the netdev notifier (under said lock)
or when socket is completely dead and no resync can
happen.

The other access to ctx->netdev in tls_validate_xmit_skb()
does not dereference the pointer, it just checks it against
other device pointer, so it should be pretty safe (perhaps
we can add a READ_ONCE/WRITE_ONCE there, if paranoid).

Fixes: 4799ac81 ("tls: Add rx inline crypto offload")
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NDirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Jakub Kicinski says:

====================
Documentation: tls: add offload documentation

This set adds documentation for TLS offload. It starts
by making the networking documentation a little easier
to navigate by hiding driver docs a little deeper.
It then RSTifys the existing Kernel TLS documentation.
Last but not least TLS offload documentation is added.
This should help vendors navigate the TLS offload, and
help ensure different implementations stay aligned from
user perspective.

v2:
 - address Alexei's and Boris'es commands on patch 3.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Describe existing kernel TLS offload (added back in Linux 4.19) -
the mechanism, the expected behavior and the notable corner cases.

This documentation is mostly targeting hardware vendors who want
to implement offload, to ensure consistency between implementations.

v2:
 - add emphasis around TLS_SW/TLS_HW/TLS_HW_RECORD;
 - remove mentions of ongoing work (Boris);
 - split the flow of data in SW vs. HW cases in TX overview
   (Boris);
 - call out which fields are updated by the device and which
   are filled by the stack (Boris);
 - move error handling into it's own section (Boris);
 - add more words about fallback (Boris);
 - note that checksum validation is required (Alexei);
 - note that drivers shouldn't pay attention to the TLS
   device features.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: NDave Watson <davejwatson@fb.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NBoris Pismenny <borisp@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Convert the TLS doc to RST.  Use C code blocks for the code
samples, and mark hyperlinks.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: NDave Watson <davejwatson@fb.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>