unlocked version of protocol level close, will be used by
MPTCP to allow decouple orphaning and subflow level close.
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Will be needed by the next patch, as MPTCP needs to handle
directly the error/memory-allocation-needed path.

No functional changes intended.

Additionally let MPTCP code access the tcp_remove_empty_skb()
helper.
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Both IPv4 and IPv6 needs it via a function pointer.
Following patch will avoid the indirect call.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

During TCP fast recovery, the congestion control in charge is by
default the Proportional Rate Reduction (PRR) unless the congestion
control module specified otherwise (e.g. BBR).

Previously when tcp_packets_in_flight() is below snd_ssthresh PRR
would slow start upon receiving an ACK that
   1) cumulatively acknowledges retransmitted data
   and
   2) does not detect further lost retransmission

Such conditions indicate the repair is in good steady progress
after the first round trip of recovery. Otherwise PRR adopts the
packet conservation principle to send only the amount that was
newly delivered (indicated by this ACK).

This patch generalizes the previous design principle to include
also the newly sent data beside retransmission: as long as
the delivery is making good progress, both retransmission and
new data should be accounted to make PRR more cautious in slow
starting.
Suggested-by: NMatt Mathis <mattmathis@google.com>
Suggested-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NYuchung Cheng <ycheng@google.com>
Signed-off-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20201031013412.1973112-1-ycheng@google.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

The commit 0813a841 ("bpf: tcp: Allow bpf prog to write and parse TCP header option")
unnecessarily introduced bpf_skops_init_child() which limited the child
sk from inheriting all bpf_sock_ops_cb_flags of the listen sk.  That
breaks existing user expectation.

This patch removes the bpf_skops_init_child() and just allows
sock_copy() to do its job to copy everything from listen sk to
the child sk.

Fixes: 0813a841 ("bpf: tcp: Allow bpf prog to write and parse TCP header option")
Reported-by: NStanislav Fomichev <sdf@google.com>
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201002013448.2542025-1-kafai@fb.com

That is needed to let the subflows announce promptly when new
space is available in the receive buffer.

tcp_cleanup_rbuf() is currently a static function, drop the
scope modifier and add a declaration in the TCP header.
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Now that the previous patches ensure that all call sites for
tcp_set_congestion_control() want to initialize congestion control, we
can simplify tcp_set_congestion_control() by removing the reinit
argument and the code to support it.
Signed-off-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NYuchung Cheng <ycheng@google.com>
Acked-by: NKevin Yang <yyd@google.com>
Cc: Lawrence Brakmo <brakmo@fb.com>

The arg exact_dif is not used anymore, remove it. inet_exact_dif_match()
is no longer needed after the above is removed, so remove it too.
Signed-off-by: NMiaohe Lin <linmiaohe@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

[ Note: The TCP changes here is mainly to implement the bpf
  pieces into the bpf_skops_*() functions introduced
  in the earlier patches. ]

The earlier effort in BPF-TCP-CC allows the TCP Congestion Control
algorithm to be written in BPF.  It opens up opportunities to allow
a faster turnaround time in testing/releasing new congestion control
ideas to production environment.

The same flexibility can be extended to writing TCP header option.
It is not uncommon that people want to test new TCP header option
to improve the TCP performance.  Another use case is for data-center
that has a more controlled environment and has more flexibility in
putting header options for internal only use.

For example, we want to test the idea in putting maximum delay
ACK in TCP header option which is similar to a draft RFC proposal [1].

This patch introduces the necessary BPF API and use them in the
TCP stack to allow BPF_PROG_TYPE_SOCK_OPS program to parse
and write TCP header options.  It currently supports most of
the TCP packet except RST.

Supported TCP header option:
───────────────────────────
This patch allows the bpf-prog to write any option kind.
Different bpf-progs can write its own option by calling the new helper
bpf_store_hdr_opt().  The helper will ensure there is no duplicated
option in the header.

By allowing bpf-prog to write any option kind, this gives a lot of
flexibility to the bpf-prog.  Different bpf-prog can write its
own option kind.  It could also allow the bpf-prog to support a
recently standardized option on an older kernel.

Sockops Callback Flags:
──────────────────────
The bpf program will only be called to parse/write tcp header option
if the following newly added callback flags are enabled
in tp->bpf_sock_ops_cb_flags:
BPF_SOCK_OPS_PARSE_UNKNOWN_HDR_OPT_CB_FLAG
BPF_SOCK_OPS_PARSE_ALL_HDR_OPT_CB_FLAG
BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG

A few words on the PARSE CB flags.  When the above PARSE CB flags are
turned on, the bpf-prog will be called on packets received
at a sk that has at least reached the ESTABLISHED state.
The parsing of the SYN-SYNACK-ACK will be discussed in the
"3 Way HandShake" section.

The default is off for all of the above new CB flags, i.e. the bpf prog
will not be called to parse or write bpf hdr option.  There are
details comment on these new cb flags in the UAPI bpf.h.

sock_ops->skb_data and bpf_load_hdr_opt()
─────────────────────────────────────────
sock_ops->skb_data and sock_ops->skb_data_end covers the whole
TCP header and its options.  They are read only.

The new bpf_load_hdr_opt() helps to read a particular option "kind"
from the skb_data.

Please refer to the comment in UAPI bpf.h.  It has details
on what skb_data contains under different sock_ops->op.

3 Way HandShake
───────────────
The bpf-prog can learn if it is sending SYN or SYNACK by reading the
sock_ops->skb_tcp_flags.

* Passive side

When writing SYNACK (i.e. sock_ops->op == BPF_SOCK_OPS_WRITE_HDR_OPT_CB),
the received SYN skb will be available to the bpf prog.  The bpf prog can
use the SYN skb (which may carry the header option sent from the remote bpf
prog) to decide what bpf header option should be written to the outgoing
SYNACK skb.  The SYN packet can be obtained by getsockopt(TCP_BPF_SYN*).
More on this later.  Also, the bpf prog can learn if it is in syncookie
mode (by checking sock_ops->args[0] == BPF_WRITE_HDR_TCP_SYNACK_COOKIE).

The bpf prog can store the received SYN pkt by using the existing
bpf_setsockopt(TCP_SAVE_SYN).  The example in a later patch does it.
[ Note that the fullsock here is a listen sk, bpf_sk_storage
  is not very useful here since the listen sk will be shared
  by many concurrent connection requests.

  Extending bpf_sk_storage support to request_sock will add weight
  to the minisock and it is not necessary better than storing the
  whole ~100 bytes SYN pkt. ]

When the connection is established, the bpf prog will be called
in the existing PASSIVE_ESTABLISHED_CB callback.  At that time,
the bpf prog can get the header option from the saved syn and
then apply the needed operation to the newly established socket.
The later patch will use the max delay ack specified in the SYN
header and set the RTO of this newly established connection
as an example.

The received ACK (that concludes the 3WHS) will also be available to
the bpf prog during PASSIVE_ESTABLISHED_CB through the sock_ops->skb_data.
It could be useful in syncookie scenario.  More on this later.

There is an existing getsockopt "TCP_SAVED_SYN" to return the whole
saved syn pkt which includes the IP[46] header and the TCP header.
A few "TCP_BPF_SYN*" getsockopt has been added to allow specifying where to
start getting from, e.g. starting from TCP header, or from IP[46] header.

The new getsockopt(TCP_BPF_SYN*) will also know where it can get
the SYN's packet from:
  - (a) the just received syn (available when the bpf prog is writing SYNACK)
        and it is the only way to get SYN during syncookie mode.
  or
  - (b) the saved syn (available in PASSIVE_ESTABLISHED_CB and also other
        existing CB).

The bpf prog does not need to know where the SYN pkt is coming from.
The getsockopt(TCP_BPF_SYN*) will hide this details.

Similarly, a flags "BPF_LOAD_HDR_OPT_TCP_SYN" is also added to
bpf_load_hdr_opt() to read a particular header option from the SYN packet.

* Fastopen

Fastopen should work the same as the regular non fastopen case.
This is a test in a later patch.

* Syncookie

For syncookie, the later example patch asks the active
side's bpf prog to resend the header options in ACK.  The server
can use bpf_load_hdr_opt() to look at the options in this
received ACK during PASSIVE_ESTABLISHED_CB.

* Active side

The bpf prog will get a chance to write the bpf header option
in the SYN packet during WRITE_HDR_OPT_CB.  The received SYNACK
pkt will also be available to the bpf prog during the existing
ACTIVE_ESTABLISHED_CB callback through the sock_ops->skb_data
and bpf_load_hdr_opt().

* Turn off header CB flags after 3WHS

If the bpf prog does not need to write/parse header options
beyond the 3WHS, the bpf prog can clear the bpf_sock_ops_cb_flags
to avoid being called for header options.
Or the bpf-prog can select to leave the UNKNOWN_HDR_OPT_CB_FLAG on
so that the kernel will only call it when there is option that
the kernel cannot handle.

[1]: draft-wang-tcpm-low-latency-opt-00
     https://tools.ietf.org/html/draft-wang-tcpm-low-latency-opt-00Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200820190104.2885895-1-kafai@fb.com

The bpf prog needs to parse the SYN header to learn what options have
been sent by the peer's bpf-prog before writing its options into SYNACK.
This patch adds a "syn_skb" arg to tcp_make_synack() and send_synack().
This syn_skb will eventually be made available (as read-only) to the
bpf prog.  This will be the only SYN packet available to the bpf
prog during syncookie.  For other regular cases, the bpf prog can
also use the saved_syn.

When writing options, the bpf prog will first be called to tell the
kernel its required number of bytes.  It is done by the new
bpf_skops_hdr_opt_len().  The bpf prog will only be called when the new
BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG is set in tp->bpf_sock_ops_cb_flags.
When the bpf prog returns, the kernel will know how many bytes are needed
and then update the "*remaining" arg accordingly.  4 byte alignment will
be included in the "*remaining" before this function returns.  The 4 byte
aligned number of bytes will also be stored into the opts->bpf_opt_len.
"bpf_opt_len" is a newly added member to the struct tcp_out_options.

Then the new bpf_skops_write_hdr_opt() will call the bpf prog to write the
header options.  The bpf prog is only called if it has reserved spaces
before (opts->bpf_opt_len > 0).

The bpf prog is the last one getting a chance to reserve header space
and writing the header option.

These two functions are half implemented to highlight the changes in
TCP stack.  The actual codes preparing the bpf running context and
invoking the bpf prog will be added in the later patch with other
necessary bpf pieces.
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Reviewed-by: NEric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/bpf/20200820190052.2885316-1-kafai@fb.com

In tcp_init_transfer(), it currently calls the bpf prog to give it a
chance to handle the just "ESTABLISHED" event (e.g. do setsockopt
on the newly established sk).  Right now, it is done by calling the
general purpose tcp_call_bpf().

In the later patch, it also needs to pass the just-received skb which
concludes the 3 way handshake. E.g. the SYNACK received at the active side.
The bpf prog can then learn some specific header options written by the
peer's bpf-prog and potentially do setsockopt on the newly established sk.
Thus, instead of reusing the general purpose tcp_call_bpf(), a new function
bpf_skops_established() is added to allow passing the "skb" to the bpf
prog.  The actual skb passing from bpf_skops_established() to the bpf prog
will happen together in a later patch which has the necessary bpf pieces.

A "skb" arg is also added to tcp_init_transfer() such that
it can then be passed to bpf_skops_established().

Calling the new bpf_skops_established() instead of tcp_call_bpf()
should be a noop in this patch.
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200820190039.2884750-1-kafai@fb.com

This patch adds bpf_setsockopt(TCP_BPF_RTO_MIN) to allow bpf prog
to set the min rto of a connection.  It could be used together
with the earlier patch which has added bpf_setsockopt(TCP_BPF_DELACK_MAX).

A later selftest patch will communicate the max delay ack in a
bpf tcp header option and then the receiving side can use
bpf_setsockopt(TCP_BPF_RTO_MIN) to set a shorter rto.
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Reviewed-by: NEric Dumazet <edumazet@google.com>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200820190027.2884170-1-kafai@fb.com

When TFO keys are read back on big endian systems either via the global
sysctl interface or via getsockopt() using TCP_FASTOPEN_KEY, the values
don't match what was written.

For example, on s390x:

# echo "1-2-3-4" > /proc/sys/net/ipv4/tcp_fastopen_key
# cat /proc/sys/net/ipv4/tcp_fastopen_key
02000000-01000000-04000000-03000000

Instead of:

# cat /proc/sys/net/ipv4/tcp_fastopen_key
00000001-00000002-00000003-00000004

Fix this by converting to the correct endianness on read. This was
reported by Colin Ian King when running the 'tcp_fastopen_backup_key' net
selftest on s390x, which depends on the read value matching what was
written. I've confirmed that the test now passes on big and little endian
systems.
Signed-off-by: NJason Baron <jbaron@akamai.com>
Fixes: 438ac880 ("net: fastopen: robustness and endianness fixes for SipHash")
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Eric Dumazet <edumazet@google.com>
Reported-and-tested-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If SYN packet contains MP_CAPABLE option, keep it enabled.
Syncokie validation and cookie-based socket creation is changed to
instantiate an mptcp request sockets if the ACK contains an MPTCP
connection request.

Rather than extend both cookie_v4/6_check, add a common helper to create
the (mp)tcp request socket.
Suggested-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Rework the remaining setsockopt code to pass a sockptr_t instead of a
plain user pointer.  This removes the last remaining set_fs(KERNEL_DS)
outside of architecture specific code.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: Stefan Schmidt <stefan@datenfreihafen.org> [ieee802154]
Acked-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Pass a sockptr_t to prepare for set_fs-less handling of the kernel
pointer from bpf-cgroup.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Handle the few cases that need special treatment in-line using
in_compat_syscall().  This also removes all the now unused
compat_{get,set}sockopt methods.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

A new field bpf_seq_afinfo is added to tcp_iter_state
to provide bpf tcp iterator afinfo. There are two
reasons on why we did this.

First, the current way to get afinfo from PDE_DATA
does not work for bpf iterator as its seq_file
inode does not conform to /proc/net/{tcp,tcp6}
inode structures. More specifically, anonymous
bpf iterator will use an anonymous inode which
is shared in the system and we cannot change inode
private data structure at all.

Second, bpf iterator for tcp/tcp6 wants to
traverse all tcp and tcp6 sockets in one pass
and bpf program can control whether they want
to skip one sk_family or not. Having a different
afinfo with family AF_UNSPEC make it easier
to understand in the code.

This patch does not change /proc/net/{tcp,tcp6} behavior
as the bpf_seq_afinfo will be NULL for these two proc files.
Signed-off-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200623230804.3987829-1-yhs@fb.com

This patch removes following (C=1 W=1) warnings for CONFIG_RETPOLINE=y :

net/ipv4/tcp_offload.c:306:16: warning: symbol 'tcp4_gro_receive' was not declared. Should it be static?
net/ipv4/tcp_offload.c:306:17: warning: no previous prototype for 'tcp4_gro_receive' [-Wmissing-prototypes]
net/ipv4/tcp_offload.c:319:29: warning: symbol 'tcp4_gro_complete' was not declared. Should it be static?
net/ipv4/tcp_offload.c:319:29: warning: no previous prototype for 'tcp4_gro_complete' [-Wmissing-prototypes]
  CHECK   net/ipv6/tcpv6_offload.c
net/ipv6/tcpv6_offload.c:16:16: warning: symbol 'tcp6_gro_receive' was not declared. Should it be static?
net/ipv6/tcpv6_offload.c:29:29: warning: symbol 'tcp6_gro_complete' was not declared. Should it be static?
  CC      net/ipv6/tcpv6_offload.o
net/ipv6/tcpv6_offload.c:16:17: warning: no previous prototype for 'tcp6_gro_receive' [-Wmissing-prototypes]
   16 | struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb)
      |                 ^~~~~~~~~~~~~~~~
net/ipv6/tcpv6_offload.c:29:29: warning: no previous prototype for 'tcp6_gro_complete' [-Wmissing-prototypes]
   29 | INDIRECT_CALLABLE_SCOPE int tcp6_gro_complete(struct sk_buff *skb, int thoff)
      |                             ^~~~~~~~~~~~~~~~~
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Declare ipv4_specific once, in tcp.h were it belongs.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

ipv6_specific should be declared in tcp include files,
not mptcp.

This removes the following warning :
  CHECK   net/ipv6/tcp_ipv6.c
net/ipv6/tcp_ipv6.c:78:42: warning: symbol 'ipv6_specific' was not declared. Should it be static?
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Remove these errors:

net/ipv6/tcp_ipv6.c:1550:29: warning: symbol 'tcp_v6_rcv' was not declared. Should it be static?
net/ipv6/tcp_ipv6.c:1770:30: warning: symbol 'tcp_v6_early_demux' was not declared. Should it be static?

net/ipv6/tcp_ipv6.c:1550:29: warning: no previous prototype for 'tcp_v6_rcv' [-Wmissing-prototypes]
 1550 | INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
      |                             ^~~~~~~~~~
net/ipv6/tcp_ipv6.c:1770:30: warning: no previous prototype for 'tcp_v6_early_demux' [-Wmissing-prototypes]
 1770 | INDIRECT_CALLABLE_SCOPE void tcp_v6_early_demux(struct sk_buff *skb)
      |                              ^~~~~~~~~~~~~~~~~~
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Mitigate RETPOLINE costs in __tcp_transmit_skb()
by using INDIRECT_CALL_INET() wrapper.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Mitigate RETPOLINE costs in __tcp_transmit_skb()
by using INDIRECT_CALL_INET() wrapper.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As of commit 98fa6271
("tcp: refactor setting the initial congestion window") this is called
only from tcp_input.c, so it can be static.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Reviewed-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Make tcp_ld_RTO_revert() helper available to IPv6, and
implement RFC 6069 :

Quoting this RFC :

3. Connectivity Disruption Indication

   For Internet Protocol version 6 (IPv6) [RFC2460], the counterpart of
   the ICMP destination unreachable message of code 0 (net unreachable)
   and of code 1 (host unreachable) is the ICMPv6 destination
   unreachable message of code 0 (no route to destination) [RFC4443].
   As with IPv4, a router should generate an ICMPv6 destination
   unreachable message of code 0 in response to a packet that cannot be
   delivered to its destination address because it lacks a matching
   entry in its routing table.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Acked-by: NYuchung Cheng <ycheng@google.com>
Acked-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We autotune rcvbuf whenever SO_RCVLOWAT is set to account for 100%
overhead in tcp_set_rcvlowat()

This works well when skb->len/skb->truesize ratio is bigger than 0.5

But if we receive packets with small MSS, we can end up in a situation
where not enough bytes are available in the receive queue to satisfy
RCVLOWAT setting.
As our sk_rcvbuf limit is hit, we send zero windows in ACK packets,
preventing remote peer from sending more data.

Even autotuning does not help, because it only triggers at the time
user process drains the queue. If no EPOLLIN is generated, this
can not happen.

Note poll() has a similar issue, after commit
c7004482 ("tcp: Respect SO_RCVLOWAT in tcp_poll().")

Fixes: 03f45c88 ("tcp: avoid extra wakeups for SO_RCVLOWAT users")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Acked-by: NSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

<linux/cryptohash.h> sounds very generic and important, like it's the
header to include if you're doing cryptographic hashing in the kernel.
But actually it only includes the library implementation of the SHA-1
compression function (not even the full SHA-1).  This should basically
never be used anymore; SHA-1 is no longer considered secure, and there
are much better ways to do cryptographic hashing in the kernel.

Most files that include this header don't actually need it.  So in
preparation for removing it, remove all these unneeded includes of it.
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

it doesn't actually exist...

Test: builds and 'git grep tcp_default_init_rwnd' comes up empty
Signed-off-by: NMaciej Żenczykowski <maze@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

With the addition of horizon feature to sch_fq, we noticed some
suboptimal behavior of extremely low pacing rate TCP flows, especially
when TCP is not aware of a drop happening in lower stacks.

Back in commit 3f80e08f ("tcp: add tcp_reset_xmit_timer() helper"),
tcp_pacing_delay() was added to estimate an extra delay to add to standard
rto timers.

This patch removes the skb argument from this helper and
tcp_reset_xmit_timer() because it makes more sense to simply
consider the time at which next packet is allowed to be sent,
instead of the time of whatever packet has been sent.

This avoids arming RTO timer too soon and removes
spurious horizon drops.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch changes the behavior of TCP_LINGER2 about its limit. The
sysctl_tcp_fin_timeout used to be the limit of TCP_LINGER2 but now it's
only the default value. A new macro named TCP_FIN_TIMEOUT_MAX is added
as the limit of TCP_LINGER2, which is 2 minutes.

Since TCP_LINGER2 used sysctl_tcp_fin_timeout as the default value
and the limit in the past, the system administrator cannot set the
default value for most of sockets and let some sockets have a greater
timeout. It might be a mistake that let the sysctl to be the limit of
the TCP_LINGER2. Maybe we can add a new sysctl to set the max of
TCP_LINGER2, but FIN-WAIT-2 timeout is usually no need to be too long
and 2 minutes are legal considering TCP specs.

Changes in v3:
- Remove the new socket option and change the TCP_LINGER2 behavior so
  that the timeout can be set to value between sysctl_tcp_fin_timeout
  and 2 minutes.

Changes in v2:
- Add int overflow check for the new socket option.

Changes in v1:
- Add a new socket option to set timeout greater than
  sysctl_tcp_fin_timeout.
Signed-off-by: NCambda Zhu <cambda@linux.alibaba.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

TCP stack is dumb in how it cooks its output packets.

Depending on MAX_HEADER value, we might chose a bad ending point
for the headers.

If we align the end of TCP headers to cache line boundary, we
make sure to always use the smallest number of cache lines,
which always help.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: NSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

After commit f747632b ("bpf: sockmap: Move generic sockmap
hooks from BPF TCP"), tcp_bpf_recvmsg() is not used out of
tcp_bpf.c, so make it static and remove it from tcp.h. Also move
it to BPF_STREAM_PARSER #ifdef to fix unused function warnings.

Fixes: f747632b ("bpf: sockmap: Move generic sockmap hooks from BPF TCP")
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200320023426.60684-3-yuehaibing@huawei.com

The init, close and unhash handlers from TCP sockmap are generic,
and can be reused by UDP sockmap. Move the helpers into the sockmap code
base and expose them. This requires tcp_bpf_get_proto and tcp_bpf_clone to
be conditional on BPF_STREAM_PARSER.

The moved functions are unmodified, except that sk_psock_unlink is
renamed to sock_map_unlink to better match its behaviour.
Signed-off-by: NLorenz Bauer <lmb@cloudflare.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: NJakub Sitnicki <jakub@cloudflare.com>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200309111243.6982-6-lmb@cloudflare.com

tcp_bpf.c is only included in the build if CONFIG_NET_SOCK_MSG is
selected. The declaration should therefore be guarded as such.
Signed-off-by: NLorenz Bauer <lmb@cloudflare.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: NJakub Sitnicki <jakub@cloudflare.com>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200309111243.6982-5-lmb@cloudflare.com

We need to ensure that sk->sk_prot uses certain callbacks, so that
code that directly calls e.g. tcp_sendmsg in certain corner cases
works. To avoid spurious asserts, we must to do this only if
sk_psock_update_proto has not yet been called. The same invariants
apply for tcp_bpf_check_v6_needs_rebuild, so move the call as well.

Doing so allows us to merge tcp_bpf_init and tcp_bpf_reinit.
Signed-off-by: NLorenz Bauer <lmb@cloudflare.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: NJakub Sitnicki <jakub@cloudflare.com>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200309111243.6982-4-lmb@cloudflare.com

Prepare for cloning listening sockets that have their protocol callbacks
overridden by sk_msg. Child sockets must not inherit parent callbacks that
access state stored in sk_user_data owned by the parent.

Restore the child socket protocol callbacks before it gets hashed and any
of the callbacks can get invoked.
Signed-off-by: NJakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200218171023.844439-4-jakub@cloudflare.com

When sockmap sock with TLS enabled is removed we cleanup bpf/psock state
and call tcp_update_ulp() to push updates to TLS ULP on top. However, we
don't push the write_space callback up and instead simply overwrite the
op with the psock stored previous op. This may or may not be correct so
to ensure we don't overwrite the TLS write space hook pass this field to
the ULP and have it fixup the ctx.

This completes a previous fix that pushed the ops through to the ULP
but at the time missed doing this for write_space, presumably because
write_space TLS hook was added around the same time.

Fixes: 95fa1454 ("bpf: sockmap/tls, close can race with map free")
Signed-off-by: NJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: NJakub Sitnicki <jakub@cloudflare.com>
Acked-by: NJonathan Lemon <jonathan.lemon@gmail.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/bpf/20200111061206.8028-4-john.fastabend@gmail.com

MPTCP will make use of tcp_send_mss() and tcp_push() when sending
data to specific TCP subflows.

tcp_request_sock_ipvX_ops and ipvX_specific will be referenced
during TCP subflow creation.
Co-developed-by: NPeter Krystad <peter.krystad@linux.intel.com>
Signed-off-by: NPeter Krystad <peter.krystad@linux.intel.com>
Reviewed-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Coalesce and collapse of packets carrying MPTCP extensions is allowed
when the newer packet has no extension or the extensions carried by both
packets are equal.

This allows merging of TSO packet trains and even cross-TSO packets, and
does not require any additional action when moving data into existing
SKBs.

v3 -> v4:
 - allow collapsing, under mptcp_skb_can_collapse() constraint

v5 -> v6:
 - clarify MPTCP skb extensions must always be cleared at allocation
   time
Co-developed-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>