tcp_metrics: use parallel_ops for tcp_metrics_nl_family

TCP_METRICS_CMD_GET and TCP_METRICS_CMD_DEL use their
own locking (tcp_metrics_lock and RCU),
they do not need genl_mutex protection.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240416162025.1251547-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tcp_metrics: fix tcp_metrics_nl_dump() return value

Change tcp_metrics_nl_dump() to return 0 at the end
of a dump so that NLMSG_DONE can be appended
to the current skb, saving one recvmsg() system call.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240416161112.1199265-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tcp_metrics: optimize tcp_metrics_flush_all()

This is inspired by several syzbot reports where
tcp_metrics_flush_all() was seen in the traces.

We can avoid acquiring tcp_metrics_lock for empty buckets,
and we should add one cond_resched() to break potential long loops.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

tcp_metrics: do not create an entry from tcp_init_metrics()

tcp_init_metrics() only wants to get metrics if they were
previously stored in the cache. Creating an entry is adding
useless costs, especially when tcp_no_metrics_save is set.

Fixes: 51c5d0c4b169 ("tcp: Maintain dynamic metrics in local cache.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

tcp_metrics: properly set tp->snd_ssthresh in tcp_init_metrics()

We need to set tp->snd_ssthresh to TCP_INFINITE_SSTHRESH
in the case tcp_get_metrics() fails for some reason.

Fixes: 9ad7c049f0f7 ("tcp: RFC2988bis + taking RTT sample from 3WHS for the passive open side")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

tcp_metrics: add missing barriers on delete

When removing an item from RCU protected list, we must prevent
store-tearing, using rcu_assign_pointer() or WRITE_ONCE().

Fixes: 04f721c671656 ("tcp_metrics: Rewrite tcp_metrics_flush_all")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

tcp_metrics: hash table allocation cleanup

After commit 098a697b497e ("tcp_metrics: Use a single hash table
for all network namespaces.") we can avoid calling tcp_net_metrics_init()
for each new netns.

Instead, rename tcp_net_metrics_init() to tcp_metrics_hash_alloc(),
and move it to __init section.

Also move tcpmhash_entries to __initdata section.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230803135417.2716879-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tcp_metrics: fix data-race in tcpm_suck_dst() vs fastopen

Whenever tcpm_new() reclaims an old entry, tcpm_suck_dst()
would overwrite data that could be read from tcp_fastopen_cache_get()
or tcp_metrics_fill_info().

We need to acquire fastopen_seqlock to maintain consistency.

For newly allocated objects, tcpm_new() can switch to kzalloc()
to avoid an extra fastopen_seqlock acquisition.

Fixes: 1fe4c481ba63 ("net-tcp: Fast Open client - cookie cache")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230802131500.1478140-7-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tcp_metrics: annotate data-races around tm->tcpm_net

tm->tcpm_net can be read or written locklessly.

Instead of changing write_pnet() and read_pnet() and potentially
hurt performance, add the needed READ_ONCE()/WRITE_ONCE()
in tm_net() and tcpm_new().

Fixes: 849e8a0ca8d5 ("tcp_metrics: Add a field tcpm_net and verify it matches on lookup")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230802131500.1478140-6-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tcp_metrics: annotate data-races around tm->tcpm_vals[]

tm->tcpm_vals[] values can be read or written locklessly.

Add needed READ_ONCE()/WRITE_ONCE() to document this,
and force use of tcp_metric_get() and tcp_metric_set()

Fixes: 51c5d0c4b169 ("tcp: Maintain dynamic metrics in local cache.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tcp_metrics: annotate data-races around tm->tcpm_lock

tm->tcpm_lock can be read or written locklessly.

Add needed READ_ONCE()/WRITE_ONCE() to document this.

Fixes: 51c5d0c4b169 ("tcp: Maintain dynamic metrics in local cache.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230802131500.1478140-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tcp_metrics: annotate data-races around tm->tcpm_stamp

tm->tcpm_stamp can be read or written locklessly.

Add needed READ_ONCE()/WRITE_ONCE() to document this.

Also constify tcpm_check_stamp() dst argument.

Fixes: 51c5d0c4b169 ("tcp: Maintain dynamic metrics in local cache.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230802131500.1478140-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tcp_metrics: fix addr_same() helper

Because v4 and v6 families use separate inetpeer trees (respectively
net->ipv4.peers and net->ipv6.peers), inetpeer_addr_cmp(a, b) assumes
a & b share the same family.

tcp_metrics use a common hash table, where entries can have different
families.

We must therefore make sure to not call inetpeer_addr_cmp()
if the families do not match.

Fixes: d39d14ffa24c ("net: Add helper function to compare inetpeer addresses")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230802131500.1478140-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

genetlink: start to validate reserved header bytes

We had historically not checked that genlmsghdr.reserved
is 0 on input which prevents us from using those precious
bytes in the future.

One use case would be to extend the cmd field, which is
currently just 8 bits wide and 256 is not a lot of commands
for some core families.

To make sure that new families do the right thing by default
put the onus of opting out of validation on existing families.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com> (NetLabel)
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: Fix data-races around sysctl_tcp_no_ssthresh_metrics_save.

While reading sysctl_tcp_no_ssthresh_metrics_save, it can be changed
concurrently. Thus, we need to add READ_ONCE() to its readers.

Fixes: 65e6d90168f3 ("net-tcp: Disable TCP ssthresh metrics cache by default")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: Fix a data-race around sysctl_tcp_nometrics_save.

While reading sysctl_tcp_nometrics_save, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: Fix data-races around sysctl_tcp_reordering.

While reading sysctl_tcp_reordering, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: add accessors to read/set tp->snd_cwnd

We had various bugs over the years with code
breaking the assumption that tp->snd_cwnd is greater
than zero.

Lately, syzbot reported the WARN_ON_ONCE(!tp->prior_cwnd) added
in commit 8b8a321ff72c ("tcp: fix zero cwnd in tcp_cwnd_reduction")
can trigger, and without a repro we would have to spend
considerable time finding the bug.

Instead of complaining too late, we want to catch where
and when tp->snd_cwnd is set to an illegal value.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Suggested-by: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Link: https://lore.kernel.org/r/20220405233538.947344-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

genetlink: move to smaller ops wherever possible

Bulk of the genetlink users can use smaller ops, move them.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: Use generic ns_common::count

Switch over network namespaces to use the newly introduced common lifetime
counter.
Network namespaces have an additional counter named "passive". This counter
does not guarantee that the network namespace is not already de-initialized
and so isn't concerned with the actual lifetime of the network namespace;
only the "count" counter is. So the latter is moved into struct ns_common.

Currently every namespace type has its own lifetime counter which is stored
in the specific namespace struct. The lifetime counters are used
identically for all namespaces types. Namespaces may of course have
additional unrelated counters and these are not altered.

This introduces a common lifetime counter into struct ns_common. The
ns_common struct encompasses information that all namespaces share. That
should include the lifetime counter since its common for all of them.

It also allows us to unify the type of the counters across all namespaces.
Most of them use refcount_t but one uses atomic_t and at least one uses
kref. Especially the last one doesn't make much sense since it's just a
wrapper around refcount_t since 2016 and actually complicates cleanup
operations by having to use container_of() to cast the correct namespace
struct out of struct ns_common.

Having the lifetime counter for the namespaces in one place reduces
maintenance cost. Not just because after switching all namespaces over we
will have removed more code than we added but also because the logic is
more easily understandable and we indicate to the user that the basic
lifetime requirements for all namespaces are currently identical.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
[christian.brauner@ubuntu.com: rewrite commit]
Link: https://lore.kernel.org/r/159644977635.604812.1319877322927063560.stgit@localhost.localdomain
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

net-tcp: Disable TCP ssthresh metrics cache by default

This patch introduces a sysctl knob "net.ipv4.tcp_no_ssthresh_metrics_save"
that disables TCP ssthresh metrics cache by default. Other parts of TCP
metrics cache, e.g. rtt, cwnd, remain unchanged.

As modern networks becoming more and more dynamic, TCP metrics cache
today often causes more harm than benefits. For example, the same IP
address is often shared by different subscribers behind NAT in residential
networks. Even if the IP address is not shared by different users,
caching the slow-start threshold of a previous short flow using loss-based
congestion control (e.g. cubic) often causes the future longer flows of
the same network path to exit slow-start prematurely with abysmal
throughput.

Caching ssthresh is very risky and can lead to terrible performance.
Therefore it makes sense to make disabling ssthresh caching by
default and opt-in for specific networks by the administrators.
This practice also has worked well for several years of deployment with
CUBIC congestion control at Google.

Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Kevin(Yudong) Yang <yyd@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: refactor setting the initial congestion window

Relocate the congestion window initialization from tcp_init_metrics()
to tcp_init_transfer() to improve code readability.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: undo initial congestion window on false SYN timeout

Linux implements RFC6298 and use an initial congestion window of 1
upon establishing the connection if the SYN packet is retransmitted 2
or more times. In cellular networks SYN timeouts are often spurious
if the wireless radio was dormant or idle. Also some network path
is longer than the default SYN timeout. Having a minimal cwnd on
both cases are detrimental to TCP startup performance.

This patch extends TCP undo feature (RFC3522 aka TCP Eifel) to detect
spurious SYN timeout via TCP timestamps. Since tp->retrans_stamp
records the initial SYN timestamp instead of first retransmission, we
have to implement a different undo code additionally. The detection
also must happen before tcp_ack() as retrans_stamp is reset when
SYN is acknowledged.

Note this patch covers both active regular and fast open.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

genetlink: optionally validate strictly/dumps

Add options to strictly validate messages and dump messages,
sometimes perhaps validating dump messages non-strictly may
be required, so add an option for that as well.

Since none of this can really be applied to existing commands,
set the options everwhere using the following spatch:

@@
identifier ops;
expression X;
@@
struct genl_ops ops[] = {
...,
{
.cmd = X,
+ .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
...
},
...
};

For new commands one should just not copy the .validate 'opt-out'
flags and thus get strict validation.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

netlink: make nla_nest_start() add NLA_F_NESTED flag

Even if the NLA_F_NESTED flag was introduced more than 11 years ago, most
netlink based interfaces (including recently added ones) are still not
setting it in kernel generated messages. Without the flag, message parsers
not aware of attribute semantics (e.g. wireshark dissector or libmnl's
mnl_nlmsg_fprintf()) cannot recognize nested attributes and won't display
the structure of their contents.

Unfortunately we cannot just add the flag everywhere as there may be
userspace applications which check nlattr::nla_type directly rather than
through a helper masking out the flags. Therefore the patch renames
nla_nest_start() to nla_nest_start_noflag() and introduces nla_nest_start()
as a wrapper adding NLA_F_NESTED. The calls which add NLA_F_NESTED manually
are rewritten to use nla_nest_start().

Except for changes in include/net/netlink.h, the patch was generated using
this semantic patch:

@@ expression E1, E2; @@
-nla_nest_start(E1, E2)
+nla_nest_start_noflag(E1, E2)

@@ expression E1, E2; @@
-nla_nest_start_noflag(E1, E2 | NLA_F_NESTED)
+nla_nest_start(E1, E2)

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

genetlink: make policy common to family

Since maxattr is common, the policy can't really differ sanely,
so make it common as well.

The only user that did in fact manage to make a non-common policy
is taskstats, which has to be really careful about it (since it's
still using a common maxattr!). This is no longer supported, but
we can fake it using pre_doit.

This reduces the size of e.g. nl80211.o (which has lots of commands):

text data bss dec hex filename
398745 14323 2240 415308 6564c net/wireless/nl80211.o (before)
397913 14331 2240 414484 65314 net/wireless/nl80211.o (after)
--------------------------------
-832 +8 0 -824

Which is obviously just 8 bytes for each command, and an added 8
bytes for the new policy pointer. I'm not sure why the ops list is
counted as .text though.

Most of the code transformations were done using the following spatch:
@ops@
identifier OPS;
expression POLICY;
@@
struct genl_ops OPS[] = {
...,
{
- .policy = POLICY,
},
...
};

@@
identifier ops.OPS;
expression ops.POLICY;
identifier fam;
expression M;
@@
struct genl_family fam = {
.ops = OPS,
.maxattr = M,
+ .policy = POLICY,
...
};

This also gets rid of devlink_nl_cmd_region_read_dumpit() accessing
the cb->data as ops, which we want to change in a later genl patch.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mm: convert totalram_pages and totalhigh_pages variables to atomic

totalram_pages and totalhigh_pages are made static inline function.

Main motivation was that managed_page_count_lock handling was complicating
things. It was discussed in length here,
https://lore.kernel.org/patchwork/patch/995739/#1181785 So it seemes
better to remove the lock and convert variables to atomic, with preventing
poteintial store-to-read tearing as a bonus.

[akpm@linux-foundation.org: coding style fixes]
Link: http://lkml.kernel.org/r/1542090790-21750-4-git-send-email-arunks@codeaurora.org
Signed-off-by: Arun KS <arunks@codeaurora.org>
Suggested-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

net: Drop pernet_operations::async

Synchronous pernet_operations are not allowed anymore.
All are asynchronous. So, drop the structure member.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: Convert pernet_subsys, registered from inet_init()

arp_net_ops just addr/removes /proc entry.

devinet_ops allocates and frees duplicate of init_net tables
and (un)registers sysctl entries.

fib_net_ops allocates and frees pernet tables, creates/destroys
netlink socket and (un)initializes /proc entries. Foreign
pernet_operations do not touch them.

ip_rt_proc_ops only modifies pernet /proc entries.

xfrm_net_ops creates/destroys /proc entries, allocates/frees
pernet statistics, hashes and tables, and (un)initializes
sysctl files. These are not touched by foreigh pernet_operations

xfrm4_net_ops allocates/frees private pernet memory, and
configures sysctls.

sysctl_route_ops creates/destroys sysctls.

rt_genid_ops only initializes fields of just allocated net.

ipv4_inetpeer_ops allocated/frees net private memory.

igmp_net_ops just creates/destroys /proc files and socket,
noone else interested in.

tcp_sk_ops seems to be safe, because tcp_sk_init() does not
depend on any other pernet_operations modifications. Iteration
over hash table in inet_twsk_purge() is made under RCU lock,
and it's safe to iterate the table this way. Removing from
the table happen from inet_twsk_deschedule_put(), but this
function is safe without any extern locks, as it's synchronized
inside itself. There are many examples, it's used in different
context. So, it's safe to leave tcp_sk_exit_batch() unlocked.

tcp_net_metrics_ops is synchronized on tcp_metrics_lock and safe.

udplite4_net_ops only creates/destroys pernet /proc file.

icmp_sk_ops creates percpu sockets, not touched by foreign
pernet_operations.

ipmr_net_ops creates/destroys pernet fib tables, (un)registers
fib rules and /proc files. This seem to be safe to execute
in parallel with foreign pernet_operations.

af_inet_ops just sets up default parameters of newly created net.

ipv4_mib_ops creates and destroys pernet percpu statistics.

raw_net_ops, tcp4_net_ops, udp4_net_ops, ping_v4_net_ops
and ip_proc_ops only create/destroy pernet /proc files.

ip4_frags_ops creates and destroys sysctl file.

So, it's safe to make the pernet_operations async.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: Convert atomic_t net::count to refcount_t

Since net could be obtained from RCU lists,
and there is a race with net destruction,
the patch converts net::count to refcount_t.

This provides sanity checks for the cases of
incrementing counter of already dead net,
when maybe_get_net() has to used instead
of get_net().

Drivers: allyesconfig and allmodconfig are OK.

Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: pause Fast Open globally after third consecutive timeout

Prior to this patch, active Fast Open is paused on a specific
destination IP address if the previous connections to the
IP address have experienced recurring timeouts . But recent
experiments by Microsoft (https://goo.gl/cykmn7) and Mozilla
browsers indicate the isssue is often caused by broken middle-boxes
sitting close to the client. Therefore it is much better user
experience if Fast Open is disabled out-right globally to avoid
experiencing further timeouts on connections toward other
destinations.

This patch changes the destination-IP disablement to global
disablement if a connection experiencing recurring timeouts
or aborts due to timeout. Repeated incidents would still
exponentially increase the pause time, starting from an hour.
This is extremely conservative but an unfortunate compromise to
minimize bad experience due to broken middle-boxes.

Reported-by: Dragana Damjanovic <ddamjanovic@mozilla.com>
Reported-by: Patrick McManus <mcmanus@ducksong.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Wei Wang <weiwan@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: retire FACK loss detection

FACK loss detection has been disabled by default and the
successor RACK subsumed FACK and can handle reordering better.
This patch removes FACK to simplify TCP loss recovery.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Priyaranjan Jha <priyarjha@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tcp: Namespace-ify sysctl_tcp_nometrics_save

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: batch tcp_net_metrics_exit

When dealing with a list of dismantling netns, we can scan
tcp_metrics once, saving cpu cycles.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: use tcp_jiffies32 to feed tp->snd_cwnd_stamp

Use tcp_jiffies32 instead of tcp_time_stamp to feed
tp->snd_cwnd_stamp.

tcp_time_stamp will soon be a litle bit more expensive
than simply reading 'jiffies'.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

treewide: use kv[mz]alloc* rather than opencoded variants

There are many code paths opencoding kvmalloc. Let's use the helper
instead. The main difference to kvmalloc is that those users are
usually not considering all the aspects of the memory allocator. E.g.
allocation requests <= 32kB (with 4kB pages) are basically never failing
and invoke OOM killer to satisfy the allocation. This sounds too
disruptive for something that has a reasonable fallback - the vmalloc.
On the other hand those requests might fallback to vmalloc even when the
memory allocator would succeed after several more reclaim/compaction
attempts previously. There is no guarantee something like that happens
though.

This patch converts many of those places to kv[mz]alloc* helpers because
they are more conservative.

Link: http://lkml.kernel.org/r/20170306103327.2766-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> # Xen bits
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Andreas Dilger <andreas.dilger@intel.com> # Lustre
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> # KVM/s390
Acked-by: Dan Williams <dan.j.williams@intel.com> # nvdim
Acked-by: David Sterba <dsterba@suse.com> # btrfs
Acked-by: Ilya Dryomov <idryomov@gmail.com> # Ceph
Acked-by: Tariq Toukan <tariqt@mellanox.com> # mlx4
Acked-by: Leon Romanovsky <leonro@mellanox.com> # mlx5
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Santosh Raspatur <santosh@chelsio.com>
Cc: Hariprasad S <hariprasad@chelsio.com>
Cc: Yishai Hadas <yishaih@mellanox.com>
Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: "Yan, Zheng" <zyan@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tcp: remove per-destination timestamp cache

Commit 8a5bd45f6616 (tcp: randomize tcp timestamp offsets for each connection)
randomizes TCP timestamps per connection. After this commit,
there is no guarantee that the timestamps received from the
same destination are monotonically increasing. As a result,
the per-destination timestamp cache in TCP metrics (i.e., tcpm_ts
in struct tcp_metrics_block) is broken and cannot be relied upon.

Remove the per-destination timestamp cache and all related code
paths.

Note that this cache was already broken for caching timestamps of
multiple machines behind a NAT sharing the same address.

Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Cc: Lutz Vieweg <lvml@5t9.de>
Cc: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: replace dst_confirm with sk_dst_confirm

When same struct dst_entry can be used for many different
neighbours we can not use it for pending confirmations.
Use the new sk_dst_confirm() helper to propagate the
indication from received packets to sock_confirm_neigh().

Reported-by: YueHaibing <yuehaibing@huawei.com>
Fixes: 5110effee8fd ("net: Do delayed neigh confirmation.")
Fixes: f2bb4bedf35d ("ipv4: Cache output routes in fib_info nexthops.")
Tested-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: remove early retransmit

This patch removes the support of RFC5827 early retransmit (i.e.,
fast recovery on small inflight with <3 dupacks) because it is
subsumed by the new RACK loss detection. More specifically when
RACK receives DUPACKs, it'll arm a reordering timer to start fast
recovery after a quarter of (min)RTT, hence it covers the early
retransmit except RACK does not limit itself to specific inflight
or dupack numbers.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: do not export tcp_peer_is_proven()

After commit 1fb6f159fd21 ("tcp: add tcp_conn_request"),
tcp_peer_is_proven() no longer needs to be exported.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

genetlink: mark families as __ro_after_init

Now genl_register_family() is the only thing (other than the
users themselves, perhaps, but I didn't find any doing that)
writing to the family struct.

In all families that I found, genl_register_family() is only
called from __init functions (some indirectly, in which case
I've add __init annotations to clarifly things), so all can
actually be marked __ro_after_init.

This protects the data structure from accidental corruption.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

genetlink: statically initialize families

Instead of providing macros/inline functions to initialize
the families, make all users initialize them statically and
get rid of the macros.

This reduces the kernel code size by about 1.6k on x86-64
(with allyesconfig).

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

genetlink: no longer support using static family IDs

Static family IDs have never really been used, the only
use case was the workaround I introduced for those users
that assumed their family ID was also their multicast
group ID.

Additionally, because static family IDs would never be
reserved by the generic netlink code, using a relatively
low ID would only work for built-in families that can be
registered immediately after generic netlink is started,
which is basically only the control family (apart from
the workaround code, which I also had to add code for so
it would reserve those IDs)

Thus, anything other than GENL_ID_GENERATE is flawed and
luckily not used except in the cases I mentioned. Move
those workarounds into a few lines of code, and then get
rid of GENL_ID_GENERATE entirely, making it more robust.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: make nla_policy const

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

libnl: nla_put_msecs(): align on a 64-bit area

nla_data() is now aligned on a 64-bit area.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: convert cached rtt from usec to jiffies when feeding initial rto

Currently it's converted into msecs, thus HZ=1000 intact.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Fixes: 740b0f1841f6 ("tcp: switch rtt estimations to usec resolution")
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv4: Namespaceify tcp reordering sysctl knob

Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: Add helper function to compare inetpeer addresses

tcp_metrics and inetpeer both have functions to compare inetpeer
addresses. Consolidate into 1 version.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: Add set,get helpers for inetpeer addresses

Use inetpeer set,get helpers in tcp_metrics rather than peeking into
the inetpeer_addr struct.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: Introduce ipv4_addr_hash and use it for tcp metrics

Refactors a common line into helper function.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: add tcp_in_slow_start helper

Add a helper to test the slow start condition in various congestion
control modules and other places. This is to prepare a slight improvement
in policy as to exactly when to slow start.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: RFC7413 option support for Fast Open client

Fast Open has been using an experimental option with a magic number
(RFC6994). This patch makes the client by default use the RFC7413
option (34) to get and send Fast Open cookies. This patch makes
the client solicit cookies from a given server first with the
RFC7413 option. If that fails to elicit a cookie, then it tries
the RFC6994 experimental option. If that also fails, it uses the
RFC7413 option on all subsequent connect attempts. If the server
returns a Fast Open cookie then the client caches the form of the
option that successfully elicited a cookie, and uses that form on
later connects when it presents that cookie.

The idea is to gradually obsolete the use of experimental options as
the servers and clients upgrade, while keeping the interoperability
meanwhile.

Signed-off-by: Daniel Lee <Longinus00@gmail.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv4: coding style: comparison for equality with NULL

The ipv4 code uses a mixture of coding styles. In some instances check
for NULL pointer is done as x == NULL and sometimes as !x. !x is
preferred according to checkpatch and this patch makes the code
consistent by adopting the latter form.

No changes detected by objdiff.

Signed-off-by: Ian Morris <ipm@chirality.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

netlink: implement nla_get_in_addr and nla_get_in6_addr

Those are counterparts to nla_put_in_addr and nla_put_in6_addr.

Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

netlink: implement nla_put_in_addr and nla_put_in6_addr

IP addresses are often stored in netlink attributes. Add generic functions
to do that.

For nla_put_in_addr, it would be nicer to pass struct in_addr but this is
not used universally throughout the kernel, in way too many places __be32 is
used to store IPv4 address.

Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: simplify inetpeer_addr_base use

In many places, the a6 field is typecasted to struct in6_addr. As the
fields are in union anyway, just add in6_addr type to the union and get rid
of the typecasting.

Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp_metrics: fix wrong lockdep annotations

Changes in tcp_metric hash table are protected by tcp_metrics_lock
only, not by genl_mutex

While we are at it use deref_locked() instead of rcu_dereference()
in tcp_new() to avoid unnecessary barrier, as we hold tcp_metrics_lock
as well.

Reported-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: 098a697b497e ("tcp_metrics: Use a single hash table for all network namespaces.")
Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp_metrics: Use a single hash table for all network namespaces.

Now that all of the operations are safe on a single hash table
accross network namespaces, allocate a single global hash table
and update the code to use it.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp_metrics: Rewrite tcp_metrics_flush_all

Rewrite tcp_metrics_flush_all so that it can cope with entries from
different network namespaces on it's hash chain.

This is based on the logic in tcp_metrics_nl_cmd_del for deleting
a selection of entries from a tcp metrics hash chain.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp_metrics: Remove the unused return code from tcp_metrics_flush_all

tcp_metrics_flush_all always returns 0. Remove the unnecessary return code.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp_metrics: Add a field tcpm_net and verify it matches on lookup

In preparation for using one tcp metrics hash table for all network
namespaces add a field tcpm_net to struct tcp_metrics_block, and
verify that field on all hash table lookups.

Make the field tcpm_net of type possible_net_t so it takes no space
when network namespaces are disabled.

Further add a function tm_net to read that field so we can be
efficient when network namespaces are disabled and concise
the rest of the time.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp_metrics: Mix the network namespace into the hash function.

In preparation for using one hash table for all network namespaces
mix the network namespace into the hash value.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp_metrics: panic when tcp_metrics_init fails.

There is not a practical way to cleanup during boot so
just panic if there is a problem initializing tcp_metrics.

That will at least give us a clear place to start debugging
if something does go wrong.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

netlink: make nlmsg_end() and genlmsg_end() void

Contrary to common expectations for an "int" return, these functions
return only a positive value -- if used correctly they cannot even
return 0 because the message header will necessarily be in the skb.

This makes the very common pattern of

if (genlmsg_end(...) < 0) { ... }

be a whole bunch of dead code. Many places also simply do

return nlmsg_end(...);

and the caller is expected to deal with it.

This also commonly (at least for me) causes errors, because it is very
common to write

if (my_function(...))
/* error condition */

and if my_function() does "return nlmsg_end()" this is of course wrong.

Additionally, there's not a single place in the kernel that actually
needs the message length returned, and if anyone needs it later then
it'll be very easy to just use skb->len there.

Remove this, and make the functions void. This removes a bunch of dead
code as described above. The patch adds lines because I did

- return nlmsg_end(...);
+ nlmsg_end(...);
+ return 0;

I could have preserved all the function's return values by returning
skb->len, but instead I've audited all the places calling the affected
functions and found that none cared. A few places actually compared
the return value with <= 0 in dump functionality, but that could just
be changed to < 0 with no change in behaviour, so I opted for the more
efficient version.

One instance of the error I've made numerous times now is also present
in net/phonet/pn_netlink.c in the route_dumpit() function - it didn't
check for <0 or <=0 and thus broke out of the loop every single time.
I've preserved this since it will (I think) have caused the messages to
userspace to be formatted differently with just a single message for
every SKB returned to userspace. It's possible that this isn't needed
for the tools that actually use this, but I don't even know what they
are so couldn't test that changing this behaviour would be acceptable.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: don't allow syn packets without timestamps to pass tcp_tw_recycle logic

tcp_tw_recycle heavily relies on tcp timestamps to build a per-host
ordering of incoming connections and teardowns without the need to
hold state on a specific quadruple for TCP_TIMEWAIT_LEN, but only for
the last measured RTO. To do so, we keep the last seen timestamp in a
per-host indexed data structure and verify if the incoming timestamp
in a connection request is strictly greater than the saved one during
last connection teardown. Thus we can verify later on that no old data
packets will be accepted by the new connection.

During moving a socket to time-wait state we already verify if timestamps
where seen on a connection. Only if that was the case we let the
time-wait socket expire after the RTO, otherwise normal TCP_TIMEWAIT_LEN
will be used. But we don't verify this on incoming SYN packets. If a
connection teardown was less than TCP_PAWS_MSL seconds in the past we
cannot guarantee to not accept data packets from an old connection if
no timestamps are present. We should drop this SYN packet. This patch
closes this loophole.

Please note, this patch does not make tcp_tw_recycle in any way more
usable but only adds another safety check:
Sporadic drops of SYN packets because of reordering in the network or
in the socket backlog queues can happen. Users behing NAT trying to
connect to a tcp_tw_recycle enabled server can get caught in blackholes
and their connection requests may regullary get dropped because hosts
behind an address translator don't have synchronized tcp timestamp clocks.
tcp_tw_recycle cannot work if peers don't have tcp timestamps enabled.

In general, use of tcp_tw_recycle is disadvised.

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Florian Westphal <fw@strlen.de>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: don't require root to read tcp_metrics

commit d23ff7016 (tcp: add generic netlink support for tcp_metrics) introduced
netlink support for the new tcp_metrics, however it restricted getting of
tcp_metrics to root user only. This is a change from how these values could
have been fetched when in the old route cache. Unless there's a legitimate
reason to restrict the reading of these values it would be better if normal
users could fetch them.

Cc: Julian Anastasov <ja@ssi.bg>
Cc: linux-kernel@vger.kernel.org

Signed-off-by: Debabrata Banerjee <dbanerje@akamai.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: use the new API kvfree()

It is available since v3.15-rc5.

Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: switch rtt estimations to usec resolution

Upcoming congestion controls for TCP require usec resolution for RTT
estimations. Millisecond resolution is simply not enough these days.

FQ/pacing in DC environments also require this change for finer control
and removal of bimodal behavior due to the current hack in
tcp_update_pacing_rate() for 'small rtt'

TCP_CONG_RTT_STAMP is no longer needed.

As Julian Anastasov pointed out, we need to keep user compatibility :
tcp_metrics used to export RTT and RTTVAR in msec resolution,
so we added RTT_US and RTTVAR_US. An iproute2 patch is needed
to use the new attributes if provided by the kernel.

In this example ss command displays a srtt of 32 usecs (10Gbit link)

lpk51:~# ./ss -i dst lpk52
Netid State Recv-Q Send-Q Local Address:Port Peer
Address:Port
tcp ESTAB 0 1 10.246.11.51:42959
10.246.11.52:64614
cubic wscale:6,6 rto:201 rtt:0.032/0.001 ato:40 mss:1448
cwnd:10 send
3620.0Mbps pacing_rate 7240.0Mbps unacked:1 rcv_rtt:993 rcv_space:29559

Updated iproute2 ip command displays :

lpk51:~# ./ip tcp_metrics | grep 10.246.11.52
10.246.11.52 age 561.914sec cwnd 10 rtt 274us rttvar 213us source
10.246.11.51

Old binary displays :

lpk51:~# ip tcp_metrics | grep 10.246.11.52
10.246.11.52 age 561.914sec cwnd 10 rtt 250us rttvar 125us source
10.246.11.51

With help from Julian Anastasov, Stephen Hemminger and Yuchung Cheng

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Larry Brakmo <brakmo@google.com>
Cc: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: metrics: Handle v6/v4-mapped sockets in tcp-metrics

A socket may be v6/v4-mapped. In that case sk->sk_family is AF_INET6,
but the IP being used is actually an IPv4-address.
Current's tcp-metrics will thus represent it as an IPv6-address:

root@server:~# ip tcp_metrics
::ffff:10.1.1.2 age 22.920sec rtt 18750us rttvar 15000us cwnd 10
10.1.1.2 age 47.970sec rtt 16250us rttvar 10000us cwnd 10

This patch modifies the tcp-metrics so that they are able to handle the
v6/v4-mapped sockets correctly.

Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: metrics: Fix rcu-race when deleting multiple entries

In bbf852b96ebdc6d1 I introduced the tmlist, which allows to delete
multiple entries from the cache that match a specified destination if no
source-IP is specified.

However, as the cache is an RCU-list, we should not create this tmlist, as
it will change the tcpm_next pointer of the element that will be deleted
and so a thread iterating over the cache's entries while holding the
RCU-lock might get "redirected" to this tmlist.

This patch fixes this, by reverting back to the old behavior prior to
bbf852b96ebdc6d1, which means that we simply change the tcpm_next
pointer of the previous element (pp) to jump over the one we are
deleting.
The difference is that we call kfree_rcu() directly on the cache entry,
which allows us to delete multiple entries from the list.

Fixes: bbf852b96ebdc6d1 (tcp: metrics: Delete all entries matching a certain destination)
Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: metrics: Avoid duplicate entries with the same destination-IP

Because the tcp-metrics is an RCU-list, it may be that two
soft-interrupts are inside __tcp_get_metrics() for the same
destination-IP at the same time. If this destination-IP is not yet part of
the tcp-metrics, both soft-interrupts will end up in tcpm_new and create
a new entry for this IP.
So, we will have two tcp-metrics with the same destination-IP in the list.

This patch checks twice __tcp_get_metrics(). First without holding the
lock, then while holding the lock. The second one is there to confirm
that the entry has not been added by another soft-irq while waiting for
the spin-lock.

Fixes: 51c5d0c4b169b (tcp: Maintain dynamic metrics in local cache.)
Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: metrics: Allow selective get/del of tcp-metrics based on src IP

We want to be able to get/del tcp-metrics based on the src IP. This
patch adds the necessary parsing of the netlink attribute and if the
source address is set, it will match on this one too.

Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: metrics: Delete all entries matching a certain destination

As we now can have multiple entries per destination-IP, the "ip
tcp_metrics delete address ADDRESS" command deletes all of them.

Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: metrics: New netlink attribute for src IP and dumped in netlink reply

This patch adds a new netlink attribute for the source-IP and appends it
to the netlink reply. Now, iproute2 can have access to the source-IP.

Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: metrics: Add source-address to tcp-metrics

We add the source-address to the tcp-metrics, so that different metrics
will be used per source/destination-pair. We use the destination-hash to
store the metric inside the hash-table. That way, deleting and dumping
via "ip tcp_metrics" is easy.

Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: metrics: rename tcpm_addr to tcpm_daddr

As we will add also the source-address, we rename all accesses to the
tcp-metrics address to use "daddr".

Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

genetlink: only pass array to genl_register_family_with_ops()

As suggested by David Miller, make genl_register_family_with_ops()
a macro and pass only the array, evaluating ARRAY_SIZE() in the
macro, this is a little safer.

The openvswitch has some indirection, assing ops/n_ops directly in
that code. This might ultimately just assign the pointers in the
family initializations, saving the struct genl_family_and_ops and
code (once mcast groups are handled differently.)

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

genetlink: make all genl_ops users const

Now that genl_ops are no longer modified in place when
registering, they can be made const. This patch was done
mostly with spatch:

@@
identifier ops;
@@
+const
struct genl_ops ops[] = {
...
};

(except the struct thing in net/openvswitch/datapath.c)

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net-tcp: fix panic in tcp_fastopen_cache_set()

We had some reports of crashes using TCP fastopen, and Dave Jones
gave a nice stack trace pointing to the error.

Issue is that tcp_get_metrics() should not be called with a NULL dst

Fixes: 1fe4c481ba637 ("net-tcp: Fast Open client - cookie cache")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Dave Jones <davej@redhat.com>
Cc: Yuchung Cheng <ycheng@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Tested-by: Dave Jones <davej@fedoraproject.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: temporarily disable Fast Open on SYN timeout

Fast Open currently has a fall back feature to address SYN-data being
dropped but it requires the middle-box to pass on regular SYN retry
after SYN-data. This is implemented in commit aab487435 ("net-tcp:
Fast Open client - detecting SYN-data drops")

However some NAT boxes will drop all subsequent packets after first
SYN-data and blackholes the entire connections. An example is in
commit 356d7d8 "netfilter: nf_conntrack: fix tcp_in_window for Fast
Open".

The sender should note such incidents and fall back to use the regular
TCP handshake on subsequent attempts temporarily as well: after the
second SYN timeouts the original Fast Open SYN is most likely lost.
When such an event recurs Fast Open is disabled based on the number of
recurrences exponentially.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

inet: includes a sock_common in request_sock

TCP listener refactoring, part 5 :

We want to be able to insert request sockets (SYN_RECV) into main
ehash table instead of the per listener hash table to allow RCU
lookups and remove listener lock contention.

This patch includes the needed struct sock_common in front
of struct request_sock

This means there is no more inet6_request_sock IPv6 specific
structure.

Following inet_request_sock fields were renamed as they became
macros to reference fields from struct sock_common.
Prefix ir_ was chosen to avoid name collisions.

loc_port -> ir_loc_port
loc_addr -> ir_loc_addr
rmt_addr -> ir_rmt_addr
rmt_port -> ir_rmt_port
iif -> ir_iif

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: fix build errors if ipv6 is disabled

CONFIG_IPV6=n is still a valid choice ;)

It appears we can remove dead code.

Reported-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: make lookups simpler and faster

TCP listener refactoring, part 4 :

To speed up inet lookups, we moved IPv4 addresses from inet to struct
sock_common

Now is time to do the same for IPv6, because it permits us to have fast
lookups for all kind of sockets, including upcoming SYN_RECV.

Getting IPv6 addresses in TCP lookups currently requires two extra cache
lines, plus a dereference (and memory stall).

inet6_sk(sk) does the dereference of inet_sk(__sk)->pinet6

This patch is way bigger than its IPv4 counter part, because for IPv4,
we could add aliases (inet_daddr, inet_rcv_saddr), while on IPv6,
it's not doable easily.

inet6_sk(sk)->daddr becomes sk->sk_v6_daddr
inet6_sk(sk)->rcv_saddr becomes sk->sk_v6_rcv_saddr

And timewait socket also have tw->tw_v6_daddr & tw->tw_v6_rcv_saddr
at the same offset.

We get rid of INET6_TW_MATCH() as INET6_MATCH() is now the generic
macro.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: fix RTO calculated from cached RTT

Commit 1b7fdd2ab5852 ("tcp: do not use cached RTT for RTT estimation")
did not correctly account for the fact that crtt is the RTT shifted
left 3 bits. Fix the calculation to consistently reflect this fact.

Signed-off-by: Neal Cardwell <ncardwell@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-By: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: better comments for RTO initiallization

Commit 1b7fdd2ab585("tcp: do not use cached RTT for RTT estimation")
removes important comments on how RTO is initialized and updated.
Hopefully this patch puts those information back.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: do not use cached RTT for RTT estimation

RTT cached in the TCP metrics are valuable for the initial timeout
because SYN RTT usually does not account for serialization delays
on low BW path.

However using it to seed the RTT estimator maybe disruptive because
other components (e.g., pacing) require the smooth RTT to be obtained
from actual connection.

The solution is to use the higher cached RTT to set the first RTO
conservatively like tcp_rtt_estimator(), but avoid seeding the other
RTT estimator variables such as srtt. It is also a good idea to
keep RTO conservative to obtain the first RTT sample, and the
performance is insured by TCP loss probe if SYN RTT is available.

To keep the seeding formula consistent across SYN RTT and cached RTT,
the rttvar is twice the cached RTT instead of cached RTTVAR value. The
reason is because cached variation may be too small (near min RTO)
which defeats the purpose of being conservative on first RTO. However
the metrics still keep the RTT variations as they might be useful for
user applications (through ip).

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: do not expire TCP fastopen cookies

TCP metric cache expires entries after one hour.

This probably make sense for TCP RTT/RTTVAR/CWND, but not
for TCP fastopen cookies.

Its better to try previous cookie. If it appears to be obsolete,
server will send us new cookie anyway.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: handle tcp_net_metrics_init() order-5 memory allocation failures

order-5 allocations can fail with current kernels, we should
try vmalloc() as well.

Reported-by: Julien Tinnes <jln@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: Fix double sizeof in new tcp_metrics code

Fix double sizeof when parsing IPv6 address from
user space because it breaks get/del by specific IPv6 address.

Problem noticed by David Binderman:

https://bugzilla.kernel.org/show_bug.cgi?id=49171

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>

netlink: Rename pid to portid to avoid confusion

It is a frequent mistake to confuse the netlink port identifier with a
process identifier. Try to reduce this confusion by renaming fields
that hold port identifiers portid instead of pid.

I have carefully avoided changing the structures exported to
userspace to avoid changing the userspace API.

I have successfully built an allyesconfig kernel with this change.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: add generic netlink support for tcp_metrics

Add support for genl "tcp_metrics". No locking
is changed, only that now we can unlink and delete
entries after grace period. We implement get/del for
single entry and dump to support show/flush filtering
in user space. Del without address attribute causes
flush for all addresses, sadly under genl_mutex.

v2:
- remove rcu_assign_pointer as suggested by Eric Dumazet,
it is not needed because there are no other writes under lock
- move the flushing code in tcp_metrics_flush_all

v3:
- remove synchronize_rcu on flush as suggested by Eric Dumazet

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: must free metrics at net dismantle

We currently leak all tcp metrics at struct net dismantle time.

tcp_net_metrics_exit() frees the hash table, we must first
iterate it to free all metrics.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: avoid oops in tcp_metrics and reset tcpm_stamp

In tcp_tw_remember_stamp we incorrectly checked tw
instead of tm, it can lead to oops if the cached entry is
not found.

tcpm_stamp was not updated in tcpm_check_stamp when
tcpm_suck_dst was called, move the update into tcpm_suck_dst,
so that we do not call it infinitely on every next cache hit
after TCP_METRICS_TIMEOUT.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: use hash_32() in tcp_metrics

Fix a missing roundup_pow_of_two(), since tcpmhash_entries is not
guaranteed to be a power of two.

Uses hash_32() instead of custom hash.

tcpmhash_entries should be an unsigned int.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net-tcp: Fast Open client - detecting SYN-data drops

On paths with firewalls dropping SYN with data or experimental TCP options,
Fast Open connections will have experience SYN timeout and bad performance.
The solution is to track such incidents in the cookie cache and disables
Fast Open temporarily.

Since only the original SYN includes data and/or Fast Open option, the
SYN-ACK has some tell-tale sign (tcp_rcv_fastopen_synack()) to detect
such drops. If a path has recurring Fast Open SYN drops, Fast Open is
disabled for 2^(recurring_losses) minutes starting from four minutes up to
roughly one and half day. sendmsg with MSG_FASTOPEN flag will succeed but
it behaves as connect() then write().

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net-tcp: Fast Open client - cookie cache

With help from Eric Dumazet, add Fast Open metrics in tcp metrics cache.
The basic ones are MSS and the cookies. Later patch will cache more to
handle unfriendly middleboxes.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: add ipv6_addr_hash() helper

Introduce ipv6_addr_hash() helper doing a XOR on all bits
of an IPv6 address, with an optimized x86_64 version.

Use it in flow dissector, as suggested by Andrew McGregor,
to reduce hash collision probabilities in fq_codel (and other
users of flow dissector)

Use it in ip6_tunnel.c and use more bit shuffling, as suggested
by David Laight, as existing hash was ignoring most of them.

Use it in sunrpc and use more bit shuffling, using hash_32().

Use it in net/ipv6/addrconf.c, using hash_32() as well.

As a cleanup, use it in net/ipv4/tcp_metrics.c

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrew McGregor <andrewmcgr@gmail.com>
Cc: Dave Taht <dave.taht@gmail.com>
Cc: Tom Herbert <therbert@google.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: Fix out of bounds access to tcpm_vals

The recent patch "tcp: Maintain dynamic metrics in local cache." introduced
an out of bounds access due to what appears to be a typo. I believe this
change should resolve the issue by replacing the access to RTAX_CWND with
TCP_METRIC_CWND.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: Move timestamps from inetpeer to metrics cache.

With help from Lin Ming.

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

tcp: Maintain dynamic metrics in local cache.

Maintain a local hash table of TCP dynamic metrics blobs.

Computed TCP metrics are no longer maintained in the route metrics.

The table uses RCU and an extremely simple hash so that it has low
latency and low overhead. A simple hash is legitimate because we only
make metrics blobs for fully established connections.

Some tweaking of the default hash table sizes, metric timeouts, and
the hash chain length limit certainly could use some tweaking. But
the basic design seems sound.

With help from Eric Dumazet and Joe Perches.

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

tcp: Abstract back handling peer aliveness test into helper function.

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

tcp: Move dynamnic metrics handling into seperate file.

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