Commit Graph

905 Commits

Author SHA1 Message Date
Eric Dumazet 1e306ec49a tcp: fix possible sk_priority leak in tcp_v4_send_reset()
When tcp_v4_send_reset() is called with @sk == NULL,
we do not change ctl_sk->sk_priority, which could have been
set from a prior invocation.

Change tcp_v4_send_reset() to set sk_priority and sk_mark
fields before calling ip_send_unicast_reply().

This means tcp_v4_send_reset() and tcp_v4_send_ack()
no longer have to clear ctl_sk->sk_mark after
their call to ip_send_unicast_reply().

Fixes: f6c0f5d209 ("tcp: honor SO_PRIORITY in TIME_WAIT state")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Antoine Tenart <atenart@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2023-05-12 10:05:50 +01:00
Jakub Kicinski 800e68c44f Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Conflicts:

tools/testing/selftests/net/config
  62199e3f16 ("selftests: net: Add VXLAN MDB test")
  3a0385be13 ("selftests: add the missing CONFIG_IP_SCTP in net config")

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-04-13 16:04:28 -07:00
Martin KaFai Lau 580031ff99 bpf: tcp: Use sock_gen_put instead of sock_put in bpf_iter_tcp
While reviewing the udp-iter batching patches, noticed the bpf_iter_tcp
calling sock_put() is incorrect. It should call sock_gen_put instead
because bpf_iter_tcp is iterating the ehash table which has the req sk
and tw sk. This patch replaces all sock_put with sock_gen_put in the
bpf_iter_tcp codepath.

Fixes: 04c7820b77 ("bpf: tcp: Bpf iter batching and lock_sock")
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230328004232.2134233-1-martin.lau@linux.dev
2023-03-28 09:50:49 +02:00
Eric Dumazet e13ec3da05 tcp: annotate lockless access to sk->sk_err
tcp_poll() reads sk->sk_err without socket lock held/owned.

We should used READ_ONCE() here, and update writers
to use WRITE_ONCE().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2023-03-17 08:25:05 +00:00
Eric Dumazet cee1af825d tcp: annotate lockless accesses to sk->sk_err_soft
This field can be read/written without lock synchronization.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2023-03-17 08:25:05 +00:00
Eric Dumazet 2798e36dc2 tcp: add TCP_MINTTL drop reason
In the unlikely case incoming packets are dropped because
of IP_MINTTL / IPV6_MINHOPCOUNT constraints...

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230201174345.2708943-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-02-02 21:14:50 -08:00
Eric Dumazet 55fb80d518 tcp: use 2-arg optimal variant of kfree_rcu()
kfree_rcu(1-arg) should be avoided as much as possible,
since this is only possible from sleepable contexts,
and incurr extra rcu barriers.

I wish the 1-arg variant of kfree_rcu() would
get a distinct name, like kfree_rcu_slow()
to avoid it being abused.

Fixes: 459837b522 ("net/tcp: Disable TCP-MD5 static key on tcp_md5sig_info destruction")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Reviewed-by: Dmitry Safonov <dima@arista.com>
Link: https://lore.kernel.org/r/20221202052847.2623997-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-12-02 20:44:45 -08:00
Dmitry Safonov b389d1affc net/tcp: Do cleanup on tcp_md5_key_copy() failure
If the kernel was short on (atomic) memory and failed to allocate it -
don't proceed to creation of request socket. Otherwise the socket would
be unsigned and userspace likely doesn't expect that the TCP is not
MD5-signed anymore.

Signed-off-by: Dmitry Safonov <dima@arista.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-12-01 15:53:05 -08:00
Dmitry Safonov 459837b522 net/tcp: Disable TCP-MD5 static key on tcp_md5sig_info destruction
To do that, separate two scenarios:
- where it's the first MD5 key on the system, which means that enabling
  of the static key may need to sleep;
- copying of an existing key from a listening socket to the request
  socket upon receiving a signed TCP segment, where static key was
  already enabled (when the key was added to the listening socket).

Now the life-time of the static branch for TCP-MD5 is until:
- last tcp_md5sig_info is destroyed
- last socket in time-wait state with MD5 key is closed.

Which means that after all sockets with TCP-MD5 keys are gone, the
system gets back the performance of disabled md5-key static branch.

While at here, provide static_key_fast_inc() helper that does ref
counter increment in atomic fashion (without grabbing cpus_read_lock()
on CONFIG_JUMP_LABEL=y). This is needed to add a new user for
a static_key when the caller controls the lifetime of another user.

Signed-off-by: Dmitry Safonov <dima@arista.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-12-01 15:53:05 -08:00
Dmitry Safonov f62c7517ff net/tcp: Separate tcp_md5sig_info allocation into tcp_md5sig_info_add()
Add a helper to allocate tcp_md5sig_info, that will help later to
do/allocate things when info allocated, once per socket.

Signed-off-by: Dmitry Safonov <dima@arista.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-12-01 15:53:05 -08:00
Jakub Kicinski f2bb566f5c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
tools/lib/bpf/ringbuf.c
  927cbb478a ("libbpf: Handle size overflow for ringbuf mmap")
  b486d19a0a ("libbpf: checkpatch: Fixed code alignments in ringbuf.c")
https://lore.kernel.org/all/20221121122707.44d1446a@canb.auug.org.au/

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-11-29 13:04:52 -08:00
Kuniyuki Iwashima e0833d1fed dccp/tcp: Fixup bhash2 bucket when connect() fails.
If a socket bound to a wildcard address fails to connect(), we
only reset saddr and keep the port.  Then, we have to fix up the
bhash2 bucket; otherwise, the bucket has an inconsistent address
in the list.

Also, listen() for such a socket will fire the WARN_ON() in
inet_csk_get_port(). [0]

Note that when a system runs out of memory, we give up fixing the
bucket and unlink sk from bhash and bhash2 by inet_put_port().

[0]:
WARNING: CPU: 0 PID: 207 at net/ipv4/inet_connection_sock.c:548 inet_csk_get_port (net/ipv4/inet_connection_sock.c:548 (discriminator 1))
Modules linked in:
CPU: 0 PID: 207 Comm: bhash2_prev_rep Not tainted 6.1.0-rc3-00799-gc8421681c845 #63
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.amzn2022.0.1 04/01/2014
RIP: 0010:inet_csk_get_port (net/ipv4/inet_connection_sock.c:548 (discriminator 1))
Code: 74 a7 eb 93 48 8b 54 24 18 0f b7 cb 4c 89 e6 4c 89 ff e8 48 b2 ff ff 49 8b 87 18 04 00 00 e9 32 ff ff ff 0f 0b e9 34 ff ff ff <0f> 0b e9 42 ff ff ff 41 8b 7f 50 41 8b 4f 54 89 fe 81 f6 00 00 ff
RSP: 0018:ffffc900003d7e50 EFLAGS: 00010202
RAX: ffff8881047fb500 RBX: 0000000000004e20 RCX: 0000000000000000
RDX: 000000000000000a RSI: 00000000fffffe00 RDI: 00000000ffffffff
RBP: ffffffff8324dc00 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000001 R14: 0000000000004e20 R15: ffff8881054e1280
FS:  00007f8ac04dc740(0000) GS:ffff88842fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020001540 CR3: 00000001055fa003 CR4: 0000000000770ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 <TASK>
 inet_csk_listen_start (net/ipv4/inet_connection_sock.c:1205)
 inet_listen (net/ipv4/af_inet.c:228)
 __sys_listen (net/socket.c:1810)
 __x64_sys_listen (net/socket.c:1819 net/socket.c:1817 net/socket.c:1817)
 do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
 entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)
RIP: 0033:0x7f8ac051de5d
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 93 af 1b 00 f7 d8 64 89 01 48
RSP: 002b:00007ffc1c177248 EFLAGS: 00000206 ORIG_RAX: 0000000000000032
RAX: ffffffffffffffda RBX: 0000000020001550 RCX: 00007f8ac051de5d
RDX: ffffffffffffff80 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007ffc1c177270 R08: 0000000000000018 R09: 0000000000000007
R10: 0000000020001540 R11: 0000000000000206 R12: 00007ffc1c177388
R13: 0000000000401169 R14: 0000000000403e18 R15: 00007f8ac0723000
 </TASK>

Fixes: 28044fc1d4 ("net: Add a bhash2 table hashed by port and address")
Reported-by: syzbot <syzkaller@googlegroups.com>
Reported-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-11-22 20:15:37 -08:00
Kuniyuki Iwashima 8c5dae4c1a dccp/tcp: Update saddr under bhash's lock.
When we call connect() for a socket bound to a wildcard address, we update
saddr locklessly.  However, it could result in a data race; another thread
iterating over bhash might see a corrupted address.

Let's update saddr under the bhash bucket's lock.

Fixes: 3df80d9320 ("[DCCP]: Introduce DCCPv6")
Fixes: 7c657876b6 ("[DCCP]: Initial implementation")
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-11-22 20:15:36 -08:00
Kuniyuki Iwashima 77934dc6db dccp/tcp: Reset saddr on failure after inet6?_hash_connect().
When connect() is called on a socket bound to the wildcard address,
we change the socket's saddr to a local address.  If the socket
fails to connect() to the destination, we have to reset the saddr.

However, when an error occurs after inet_hash6?_connect() in
(dccp|tcp)_v[46]_conect(), we forget to reset saddr and leave
the socket bound to the address.

From the user's point of view, whether saddr is reset or not varies
with errno.  Let's fix this inconsistent behaviour.

Note that after this patch, the repro [0] will trigger the WARN_ON()
in inet_csk_get_port() again, but this patch is not buggy and rather
fixes a bug papering over the bhash2's bug for which we need another
fix.

For the record, the repro causes -EADDRNOTAVAIL in inet_hash6_connect()
by this sequence:

  s1 = socket()
  s1.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
  s1.bind(('127.0.0.1', 10000))
  s1.sendto(b'hello', MSG_FASTOPEN, (('127.0.0.1', 10000)))
  # or s1.connect(('127.0.0.1', 10000))

  s2 = socket()
  s2.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
  s2.bind(('0.0.0.0', 10000))
  s2.connect(('127.0.0.1', 10000))  # -EADDRNOTAVAIL

  s2.listen(32)  # WARN_ON(inet_csk(sk)->icsk_bind2_hash != tb2);

[0]: https://syzkaller.appspot.com/bug?extid=015d756bbd1f8b5c8f09

Fixes: 3df80d9320 ("[DCCP]: Introduce DCCPv6")
Fixes: 7c657876b6 ("[DCCP]: Initial implementation")
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-11-22 20:15:36 -08:00
xu xin 2fd450cd83 ipasdv4/tcp_ipv4: remove redundant assignment
The value of 'st->state' has been verified as "TCP_SEQ_STATE_LISTENING",
it's unnecessary to assign TCP_SEQ_STATE_LISTENING to it, so we can remove it.

Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-11-14 11:20:15 +00:00
Mubashir Adnan Qureshi 1a91bb7c3e tcp: add PLB functionality for TCP
Congestion control algorithms track PLB state and cause the connection
to trigger a path change when either of the 2 conditions is satisfied:

- No packets are in flight and (# consecutive congested rounds >=
  sysctl_tcp_plb_idle_rehash_rounds)
- (# consecutive congested rounds >= sysctl_tcp_plb_rehash_rounds)

A round (RTT) is marked as congested when congestion signal
(ECN ce_ratio) over an RTT is greater than sysctl_tcp_plb_cong_thresh.
In the event of RTO, PLB (via tcp_write_timeout()) triggers a path
change and disables congestion-triggered path changes for random time
between (sysctl_tcp_plb_suspend_rto_sec, 2*sysctl_tcp_plb_suspend_rto_sec)
to avoid hopping onto the "connectivity blackhole". RTO-triggered
path changes can still happen during this cool-off period.

Signed-off-by: Mubashir Adnan Qureshi <mubashirq@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-10-28 10:47:42 +01:00
Mubashir Adnan Qureshi bd456f283b tcp: add sysctls for TCP PLB parameters
PLB (Protective Load Balancing) is a host based mechanism for load
balancing across switch links. It leverages congestion signals(e.g. ECN)
from transport layer to randomly change the path of the connection
experiencing congestion. PLB changes the path of the connection by
changing the outgoing IPv6 flow label for IPv6 connections (implemented
in Linux by calling sk_rethink_txhash()). Because of this implementation
mechanism, PLB can currently only work for IPv6 traffic. For more
information, see the SIGCOMM 2022 paper:
  https://doi.org/10.1145/3544216.3544226

This commit adds new sysctl knobs and sets their default values for
TCP PLB.

Signed-off-by: Mubashir Adnan Qureshi <mubashirq@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-10-28 10:47:42 +01:00
Lu Wei ec791d8149 tcp: fix a signed-integer-overflow bug in tcp_add_backlog()
The type of sk_rcvbuf and sk_sndbuf in struct sock is int, and
in tcp_add_backlog(), the variable limit is caculated by adding
sk_rcvbuf, sk_sndbuf and 64 * 1024, it may exceed the max value
of int and overflow. This patch reduces the limit budget by
halving the sndbuf to solve this issue since ACK packets are much
smaller than the payload.

Fixes: c9c3321257 ("tcp: add tcp_add_backlog()")
Signed-off-by: Lu Wei <luwei32@huawei.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-10-24 13:04:25 +01:00
Jason A. Donenfeld 7e3cf0843f treewide: use get_random_{u8,u16}() when possible, part 1
Rather than truncate a 32-bit value to a 16-bit value or an 8-bit value,
simply use the get_random_{u8,u16}() functions, which are faster than
wasting the additional bytes from a 32-bit value. This was done
mechanically with this coccinelle script:

@@
expression E;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u16;
typedef __be16;
typedef __le16;
typedef u8;
@@
(
- (get_random_u32() & 0xffff)
+ get_random_u16()
|
- (get_random_u32() & 0xff)
+ get_random_u8()
|
- (get_random_u32() % 65536)
+ get_random_u16()
|
- (get_random_u32() % 256)
+ get_random_u8()
|
- (get_random_u32() >> 16)
+ get_random_u16()
|
- (get_random_u32() >> 24)
+ get_random_u8()
|
- (u16)get_random_u32()
+ get_random_u16()
|
- (u8)get_random_u32()
+ get_random_u8()
|
- (__be16)get_random_u32()
+ (__be16)get_random_u16()
|
- (__le16)get_random_u32()
+ (__le16)get_random_u16()
|
- prandom_u32_max(65536)
+ get_random_u16()
|
- prandom_u32_max(256)
+ get_random_u8()
|
- E->inet_id = get_random_u32()
+ E->inet_id = get_random_u16()
)

@@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u16;
identifier v;
@@
- u16 v = get_random_u32();
+ u16 v = get_random_u16();

@@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u8;
identifier v;
@@
- u8 v = get_random_u32();
+ u8 v = get_random_u8();

@@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u16;
u16 v;
@@
-  v = get_random_u32();
+  v = get_random_u16();

@@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u8;
u8 v;
@@
-  v = get_random_u32();
+  v = get_random_u8();

// Find a potential literal
@literal_mask@
expression LITERAL;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
position p;
@@

        ((T)get_random_u32()@p & (LITERAL))

// Examine limits
@script:python add_one@
literal << literal_mask.LITERAL;
RESULT;
@@

value = None
if literal.startswith('0x'):
        value = int(literal, 16)
elif literal[0] in '123456789':
        value = int(literal, 10)
if value is None:
        print("I don't know how to handle %s" % (literal))
        cocci.include_match(False)
elif value < 256:
        coccinelle.RESULT = cocci.make_ident("get_random_u8")
elif value < 65536:
        coccinelle.RESULT = cocci.make_ident("get_random_u16")
else:
        print("Skipping large mask of %s" % (literal))
        cocci.include_match(False)

// Replace the literal mask with the calculated result.
@plus_one@
expression literal_mask.LITERAL;
position literal_mask.p;
identifier add_one.RESULT;
identifier FUNC;
@@

-       (FUNC()@p & (LITERAL))
+       (RESULT() & LITERAL)

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk> # for sch_cake
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-10-11 17:42:58 -06:00
Kuniyuki Iwashima d1e5e6408b tcp: Introduce optional per-netns ehash.
The more sockets we have in the hash table, the longer we spend looking
up the socket.  While running a number of small workloads on the same
host, they penalise each other and cause performance degradation.

The root cause might be a single workload that consumes much more
resources than the others.  It often happens on a cloud service where
different workloads share the same computing resource.

On EC2 c5.24xlarge instance (196 GiB memory and 524288 (1Mi / 2) ehash
entries), after running iperf3 in different netns, creating 24Mi sockets
without data transfer in the root netns causes about 10% performance
regression for the iperf3's connection.

 thash_entries		sockets		length		Gbps
	524288		      1		     1		50.7
			   24Mi		    48		45.1

It is basically related to the length of the list of each hash bucket.
For testing purposes to see how performance drops along the length,
I set 131072 (1Mi / 8) to thash_entries, and here's the result.

 thash_entries		sockets		length		Gbps
        131072		      1		     1		50.7
			    1Mi		     8		49.9
			    2Mi		    16		48.9
			    4Mi		    32		47.3
			    8Mi		    64		44.6
			   16Mi		   128		40.6
			   24Mi		   192		36.3
			   32Mi		   256		32.5
			   40Mi		   320		27.0
			   48Mi		   384		25.0

To resolve the socket lookup degradation, we introduce an optional
per-netns hash table for TCP, but it's just ehash, and we still share
the global bhash, bhash2 and lhash2.

With a smaller ehash, we can look up non-listener sockets faster and
isolate such noisy neighbours.  In addition, we can reduce lock contention.

We can control the ehash size by a new sysctl knob.  However, depending
on workloads, it will require very sensitive tuning, so we disable the
feature by default (net.ipv4.tcp_child_ehash_entries == 0).  Moreover,
we can fall back to using the global ehash in case we fail to allocate
enough memory for a new ehash.  The maximum size is 16Mi, which is large
enough that even if we have 48Mi sockets, the average list length is 3,
and regression would be less than 1%.

We can check the current ehash size by another read-only sysctl knob,
net.ipv4.tcp_ehash_entries.  A negative value means the netns shares
the global ehash (per-netns ehash is disabled or failed to allocate
memory).

  # dmesg | cut -d ' ' -f 5- | grep "established hash"
  TCP established hash table entries: 524288 (order: 10, 4194304 bytes, vmalloc hugepage)

  # sysctl net.ipv4.tcp_ehash_entries
  net.ipv4.tcp_ehash_entries = 524288  # can be changed by thash_entries

  # sysctl net.ipv4.tcp_child_ehash_entries
  net.ipv4.tcp_child_ehash_entries = 0  # disabled by default

  # ip netns add test1
  # ip netns exec test1 sysctl net.ipv4.tcp_ehash_entries
  net.ipv4.tcp_ehash_entries = -524288  # share the global ehash

  # sysctl -w net.ipv4.tcp_child_ehash_entries=100
  net.ipv4.tcp_child_ehash_entries = 100

  # ip netns add test2
  # ip netns exec test2 sysctl net.ipv4.tcp_ehash_entries
  net.ipv4.tcp_ehash_entries = 128  # own a per-netns ehash with 2^n buckets

When more than two processes in the same netns create per-netns ehash
concurrently with different sizes, we need to guarantee the size in
one of the following ways:

  1) Share the global ehash and create per-netns ehash

  First, unshare() with tcp_child_ehash_entries==0.  It creates dedicated
  netns sysctl knobs where we can safely change tcp_child_ehash_entries
  and clone()/unshare() to create a per-netns ehash.

  2) Control write on sysctl by BPF

  We can use BPF_PROG_TYPE_CGROUP_SYSCTL to allow/deny read/write on
  sysctl knobs.

Note that the global ehash allocated at the boot time is spread over
available NUMA nodes, but inet_pernet_hashinfo_alloc() will allocate
pages for each per-netns ehash depending on the current process's NUMA
policy.  By default, the allocation is done in the local node only, so
the per-netns hash table could fully reside on a random node.  Thus,
depending on the NUMA policy the netns is created with and the CPU the
current thread is running on, we could see some performance differences
for highly optimised networking applications.

Note also that the default values of two sysctl knobs depend on the ehash
size and should be tuned carefully:

  tcp_max_tw_buckets  : tcp_child_ehash_entries / 2
  tcp_max_syn_backlog : max(128, tcp_child_ehash_entries / 128)

As a bonus, we can dismantle netns faster.  Currently, while destroying
netns, we call inet_twsk_purge(), which walks through the global ehash.
It can be potentially big because it can have many sockets other than
TIME_WAIT in all netns.  Splitting ehash changes that situation, where
it's only necessary for inet_twsk_purge() to clean up TIME_WAIT sockets
in each netns.

With regard to this, we do not free the per-netns ehash in inet_twsk_kill()
to avoid UAF while iterating the per-netns ehash in inet_twsk_purge().
Instead, we do it in tcp_sk_exit_batch() after calling tcp_twsk_purge() to
keep it protocol-family-independent.

In the future, we could optimise ehash lookup/iteration further by removing
netns comparison for the per-netns ehash.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-09-20 10:21:50 -07:00
Kuniyuki Iwashima edc12f032a tcp: Save unnecessary inet_twsk_purge() calls.
While destroying netns, we call inet_twsk_purge() in tcp_sk_exit_batch()
and tcpv6_net_exit_batch() for AF_INET and AF_INET6.  These commands
trigger the kernel to walk through the potentially big ehash twice even
though the netns has no TIME_WAIT sockets.

  # ip netns add test
  # ip netns del test

  or

  # unshare -n /bin/true >/dev/null

When tw_refcount is 1, we need not call inet_twsk_purge() at least
for the net.  We can save such unneeded iterations if all netns in
net_exit_list have no TIME_WAIT sockets.  This change eliminates
the tax by the additional unshare() described in the next patch to
guarantee the per-netns ehash size.

Tested:

  # mount -t debugfs none /sys/kernel/debug/
  # echo cleanup_net > /sys/kernel/debug/tracing/set_ftrace_filter
  # echo inet_twsk_purge >> /sys/kernel/debug/tracing/set_ftrace_filter
  # echo function > /sys/kernel/debug/tracing/current_tracer
  # cat ./add_del_unshare.sh
  for i in `seq 1 40`
  do
      (for j in `seq 1 100` ; do  unshare -n /bin/true >/dev/null ; done) &
  done
  wait;
  # ./add_del_unshare.sh

Before the patch:

  # cat /sys/kernel/debug/tracing/trace_pipe
    kworker/u128:0-8       [031] ...1.   174.162765: cleanup_net <-process_one_work
    kworker/u128:0-8       [031] ...1.   174.240796: inet_twsk_purge <-cleanup_net
    kworker/u128:0-8       [032] ...1.   174.244759: inet_twsk_purge <-tcp_sk_exit_batch
    kworker/u128:0-8       [034] ...1.   174.290861: cleanup_net <-process_one_work
    kworker/u128:0-8       [039] ...1.   175.245027: inet_twsk_purge <-cleanup_net
    kworker/u128:0-8       [046] ...1.   175.290541: inet_twsk_purge <-tcp_sk_exit_batch
    kworker/u128:0-8       [037] ...1.   175.321046: cleanup_net <-process_one_work
    kworker/u128:0-8       [024] ...1.   175.941633: inet_twsk_purge <-cleanup_net
    kworker/u128:0-8       [025] ...1.   176.242539: inet_twsk_purge <-tcp_sk_exit_batch

After:

  # cat /sys/kernel/debug/tracing/trace_pipe
    kworker/u128:0-8       [038] ...1.   428.116174: cleanup_net <-process_one_work
    kworker/u128:0-8       [038] ...1.   428.262532: cleanup_net <-process_one_work
    kworker/u128:0-8       [030] ...1.   429.292645: cleanup_net <-process_one_work

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-09-20 10:21:50 -07:00
Kuniyuki Iwashima 4461568aa4 tcp: Access &tcp_hashinfo via net.
We will soon introduce an optional per-netns ehash.

This means we cannot use tcp_hashinfo directly in most places.

Instead, access it via net->ipv4.tcp_death_row.hashinfo.

The access will be valid only while initialising tcp_hashinfo
itself and creating/destroying each netns.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-09-20 10:21:49 -07:00
Kuniyuki Iwashima 429e42c1c5 tcp: Set NULL to sk->sk_prot->h.hashinfo.
We will soon introduce an optional per-netns ehash.

This means we cannot use the global sk->sk_prot->h.hashinfo
to fetch a TCP hashinfo.

Instead, set NULL to sk->sk_prot->h.hashinfo for TCP and get
a proper hashinfo from net->ipv4.tcp_death_row.hashinfo.

Note that we need not use sk->sk_prot->h.hashinfo if DCCP is
disabled.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-09-20 10:21:49 -07:00
Kuniyuki Iwashima e9bd0cca09 tcp: Don't allocate tcp_death_row outside of struct netns_ipv4.
We will soon introduce an optional per-netns ehash and access hash
tables via net->ipv4.tcp_death_row->hashinfo instead of &tcp_hashinfo
in most places.

It could harm the fast path because dereferences of two fields in net
and tcp_death_row might incur two extra cache line misses.  To save one
dereference, let's place tcp_death_row back in netns_ipv4 and fetch
hashinfo via net->ipv4.tcp_death_row"."hashinfo.

Note tcp_death_row was initially placed in netns_ipv4, and commit
fbb8295248 ("tcp: allocate tcp_death_row outside of struct netns_ipv4")
changed it to a pointer so that we can fire TIME_WAIT timers after freeing
net.  However, we don't do so after commit 04c494e68a ("Revert "tcp/dccp:
get rid of inet_twsk_purge()""), so we need not define tcp_death_row as a
pointer.

Also, we move refcount_dec_and_test(&tw_refcount) from tcp_sk_exit() to
tcp_sk_exit_batch() as a debug check.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-09-20 10:21:49 -07:00
Kuniyuki Iwashima 08eaef9040 tcp: Clean up some functions.
This patch adds no functional change and cleans up some functions
that the following patches touch around so that we make them tidy
and easy to review/revert.  The changes are

  - Keep reverse christmas tree order
  - Remove unnecessary init of port in inet_csk_find_open_port()
  - Use req_to_sk() once in reqsk_queue_unlink()
  - Use sock_net(sk) once in tcp_time_wait() and tcp_v[46]_connect()

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-09-20 10:21:49 -07:00
Jakub Kicinski 60ad1100d5 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
tools/testing/selftests/net/.gitignore
  sort the net-next version and use it

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-09-01 12:58:02 -07:00
Eric Dumazet 79e3602caa tcp: make global challenge ack rate limitation per net-ns and default disabled
Because per host rate limiting has been proven problematic (side channel
attacks can be based on it), per host rate limiting of challenge acks ideally
should be per netns and turned off by default.

This is a long due followup of following commits:

083ae30828 ("tcp: enable per-socket rate limiting of all 'challenge acks'")
f2b2c582e8 ("tcp: mitigate ACK loops for connections as tcp_sock")
75ff39ccc1 ("tcp: make challenge acks less predictable")

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jason Baron <jbaron@akamai.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-08-31 19:56:48 -07:00
Joanne Koong 28044fc1d4 net: Add a bhash2 table hashed by port and address
The current bind hashtable (bhash) is hashed by port only.
In the socket bind path, we have to check for bind conflicts by
traversing the specified port's inet_bind_bucket while holding the
hashbucket's spinlock (see inet_csk_get_port() and
inet_csk_bind_conflict()). In instances where there are tons of
sockets hashed to the same port at different addresses, the bind
conflict check is time-intensive and can cause softirq cpu lockups,
as well as stops new tcp connections since __inet_inherit_port()
also contests for the spinlock.

This patch adds a second bind table, bhash2, that hashes by
port and sk->sk_rcv_saddr (ipv4) and sk->sk_v6_rcv_saddr (ipv6).
Searching the bhash2 table leads to significantly faster conflict
resolution and less time holding the hashbucket spinlock.

Please note a few things:
* There can be the case where the a socket's address changes after it
has been bound. There are two cases where this happens:

  1) The case where there is a bind() call on INADDR_ANY (ipv4) or
  IPV6_ADDR_ANY (ipv6) and then a connect() call. The kernel will
  assign the socket an address when it handles the connect()

  2) In inet_sk_reselect_saddr(), which is called when rebuilding the
  sk header and a few pre-conditions are met (eg rerouting fails).

In these two cases, we need to update the bhash2 table by removing the
entry for the old address, and add a new entry reflecting the updated
address.

* The bhash2 table must have its own lock, even though concurrent
accesses on the same port are protected by the bhash lock. Bhash2 must
have its own lock to protect against cases where sockets on different
ports hash to different bhash hashbuckets but to the same bhash2
hashbucket.

This brings up a few stipulations:
  1) When acquiring both the bhash and the bhash2 lock, the bhash2 lock
  will always be acquired after the bhash lock and released before the
  bhash lock is released.

  2) There are no nested bhash2 hashbucket locks. A bhash2 lock is always
  acquired+released before another bhash2 lock is acquired+released.

* The bhash table cannot be superseded by the bhash2 table because for
bind requests on INADDR_ANY (ipv4) or IPV6_ADDR_ANY (ipv6), every socket
bound to that port must be checked for a potential conflict. The bhash
table is the only source of port->socket associations.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-08-24 19:30:07 -07:00
Jakub Kicinski 272ac32f56 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
No conflicts.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-07-28 18:21:16 -07:00
Kuniyuki Iwashima 870e3a634b tcp: Fix data-races around sysctl_tcp_reflect_tos.
While reading sysctl_tcp_reflect_tos, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.

Fixes: ac8f1710c1 ("tcp: reflect tos value received in SYN to the socket")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Wei Wang <weiwan@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-25 12:42:10 +01:00
Jakub Kicinski 6e0e846ee2 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
No conflicts.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-07-21 13:03:39 -07:00
Kuniyuki Iwashima cbfc649558 tcp: Fix a data-race around sysctl_tcp_tw_reuse.
While reading sysctl_tcp_tw_reuse, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-18 12:21:54 +01:00
sewookseo e22aa14866 net: Find dst with sk's xfrm policy not ctl_sk
If we set XFRM security policy by calling setsockopt with option
IPV6_XFRM_POLICY, the policy will be stored in 'sock_policy' in 'sock'
struct. However tcp_v6_send_response doesn't look up dst_entry with the
actual socket but looks up with tcp control socket. This may cause a
problem that a RST packet is sent without ESP encryption & peer's TCP
socket can't receive it.
This patch will make the function look up dest_entry with actual socket,
if the socket has XFRM policy(sock_policy), so that the TCP response
packet via this function can be encrypted, & aligned on the encrypted
TCP socket.

Tested: We encountered this problem when a TCP socket which is encrypted
in ESP transport mode encryption, receives challenge ACK at SYN_SENT
state. After receiving challenge ACK, TCP needs to send RST to
establish the socket at next SYN try. But the RST was not encrypted &
peer TCP socket still remains on ESTABLISHED state.
So we verified this with test step as below.
[Test step]
1. Making a TCP state mismatch between client(IDLE) & server(ESTABLISHED).
2. Client tries a new connection on the same TCP ports(src & dst).
3. Server will return challenge ACK instead of SYN,ACK.
4. Client will send RST to server to clear the SOCKET.
5. Client will retransmit SYN to server on the same TCP ports.
[Expected result]
The TCP connection should be established.

Cc: Maciej Żenczykowski <maze@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Sehee Lee <seheele@google.com>
Signed-off-by: Sewook Seo <sewookseo@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-11 13:39:56 +01:00
Jakub Kicinski 0d8730f07c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
drivers/net/ethernet/microchip/sparx5/sparx5_switchdev.c
  9c5de246c1 ("net: sparx5: mdb add/del handle non-sparx5 devices")
  fbb89d02e3 ("net: sparx5: Allow mdb entries to both CPU and ports")

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-06-30 16:31:00 -07:00
Eric Dumazet 6f0012e351 tcp: add a missing nf_reset_ct() in 3WHS handling
When the third packet of 3WHS connection establishment
contains payload, it is added into socket receive queue
without the XFRM check and the drop of connection tracking
context.

This means that if the data is left unread in the socket
receive queue, conntrack module can not be unloaded.

As most applications usually reads the incoming data
immediately after accept(), bug has been hiding for
quite a long time.

Commit 68822bdf76 ("net: generalize skb freeing
deferral to per-cpu lists") exposed this bug because
even if the application reads this data, the skb
with nfct state could stay in a per-cpu cache for
an arbitrary time, if said cpu no longer process RX softirqs.

Many thanks to Ilya Maximets for reporting this issue,
and for testing various patches:
https://lore.kernel.org/netdev/20220619003919.394622-1-i.maximets@ovn.org/

Note that I also added a missing xfrm4_policy_check() call,
although this is probably not a big issue, as the SYN
packet should have been dropped earlier.

Fixes: b59c270104 ("[NETFILTER]: Keep conntrack reference until IPsec policy checks are done")
Reported-by: Ilya Maximets <i.maximets@ovn.org>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Florian Westphal <fw@strlen.de>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Tested-by: Ilya Maximets <i.maximets@ovn.org>
Reviewed-by: Ilya Maximets <i.maximets@ovn.org>
Link: https://lore.kernel.org/r/20220623050436.1290307-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-06-24 16:27:46 -07:00
Eric Dumazet 0defbb0af7 net: add per_cpu_fw_alloc field to struct proto
Each protocol having a ->memory_allocated pointer gets a corresponding
per-cpu reserve, that following patches will use.

Instead of having reserved bytes per socket,
we want to have per-cpu reserves.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-06-10 16:21:26 -07:00
huhai 3a2cd89bfb net: ipv4: Avoid bounds check warning
Fix the following build warning when CONFIG_IPV6 is not set:

In function ‘fortify_memcpy_chk’,
    inlined from ‘tcp_md5_do_add’ at net/ipv4/tcp_ipv4.c:1210:2:
./include/linux/fortify-string.h:328:4: error: call to ‘__write_overflow_field’ declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
  328 |    __write_overflow_field(p_size_field, size);
      |    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: huhai <huhai@kylinos.cn>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20220526101213.2392980-1-zhanggenjian@kylinos.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-05-30 21:21:12 -07:00
Jakub Kicinski d7e6f58360 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
drivers/net/ethernet/mellanox/mlx5/core/main.c
  b33886971d ("net/mlx5: Initialize flow steering during driver probe")
  40379a0084 ("net/mlx5_fpga: Drop INNOVA TLS support")
  f2b41b32cd ("net/mlx5: Remove ipsec_ops function table")
https://lore.kernel.org/all/20220519040345.6yrjromcdistu7vh@sx1/
  16d42d3133 ("net/mlx5: Drain fw_reset when removing device")
  8324a02c34 ("net/mlx5: Add exit route when waiting for FW")
https://lore.kernel.org/all/20220519114119.060ce014@canb.auug.org.au/

tools/testing/selftests/net/mptcp/mptcp_join.sh
  e274f71540 ("selftests: mptcp: add subflow limits test-cases")
  b6e074e171 ("selftests: mptcp: add infinite map testcase")
  5ac1d2d634 ("selftests: mptcp: Add tests for userspace PM type")
https://lore.kernel.org/all/20220516111918.366d747f@canb.auug.org.au/

net/mptcp/options.c
  ba2c89e0ea ("mptcp: fix checksum byte order")
  1e39e5a32a ("mptcp: infinite mapping sending")
  ea66758c17 ("tcp: allow MPTCP to update the announced window")
https://lore.kernel.org/all/20220519115146.751c3a37@canb.auug.org.au/

net/mptcp/pm.c
  95d6865178 ("mptcp: fix subflow accounting on close")
  4d25247d3a ("mptcp: bypass in-kernel PM restrictions for non-kernel PMs")
https://lore.kernel.org/all/20220516111435.72f35dca@canb.auug.org.au/

net/mptcp/subflow.c
  ae66fb2ba6 ("mptcp: Do TCP fallback on early DSS checksum failure")
  0348c690ed ("mptcp: add the fallback check")
  f8d4bcacff ("mptcp: infinite mapping receiving")
https://lore.kernel.org/all/20220519115837.380bb8d4@canb.auug.org.au/

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-05-19 11:23:59 -07:00
Menglong Dong f8319dfd1b net: tcp: reset 'drop_reason' to NOT_SPCIFIED in tcp_v{4,6}_rcv()
The 'drop_reason' that passed to kfree_skb_reason() in tcp_v4_rcv()
and tcp_v6_rcv() can be SKB_NOT_DROPPED_YET(0), as it is used as the
return value of tcp_inbound_md5_hash().

And it can panic the kernel with NULL pointer in
net_dm_packet_report_size() if the reason is 0, as drop_reasons[0]
is NULL.

Fixes: 1330b6ef33 ("skb: make drop reason booleanable")
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-05-16 10:47:44 +01:00
Eric Dumazet 04c494e68a Revert "tcp/dccp: get rid of inet_twsk_purge()"
This reverts commits:

0dad4087a8 ("tcp/dccp: get rid of inet_twsk_purge()")
d507204d3c ("tcp/dccp: add tw->tw_bslot")

As Leonard pointed out, a newly allocated netns can happen
to reuse a freed 'struct net'.

While TCP TW timers were covered by my patches, other things were not:

1) Lookups in rx path (INET_MATCH() and INET6_MATCH()), as they look
  at 4-tuple plus the 'struct net' pointer.

2) /proc/net/tcp[6] and inet_diag, same reason.

3) hashinfo->bhash[], same reason.

Fixing all this seems risky, lets instead revert.

In the future, we might have a per netns tcp hash table, or
a per netns list of timewait sockets...

Fixes: 0dad4087a8 ("tcp/dccp: get rid of inet_twsk_purge()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Leonard Crestez <cdleonard@gmail.com>
Tested-by: Leonard Crestez <cdleonard@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-05-13 12:24:12 +01:00
Martin KaFai Lau cae3873c5b net: inet: Retire port only listening_hash
The listen sk is currently stored in two hash tables,
listening_hash (hashed by port) and lhash2 (hashed by port and address).

After commit 0ee58dad5b ("net: tcp6: prefer listeners bound to an address")
and commit d9fbc7f643 ("net: tcp: prefer listeners bound to an address"),
the TCP-SYN lookup fast path does not use listening_hash.

The commit 05c0b35709 ("tcp: seq_file: Replace listening_hash with lhash2")
also moved the seq_file (/proc/net/tcp) iteration usage from
listening_hash to lhash2.

There are still a few listening_hash usages left.
One of them is inet_reuseport_add_sock() which uses the listening_hash
to search a listen sk during the listen() system call.  This turns
out to be very slow on use cases that listen on many different
VIPs at a popular port (e.g. 443).  [ On top of the slowness in
adding to the tail in the IPv6 case ].  The latter patch has a
selftest to demonstrate this case.

This patch takes this chance to move all remaining listening_hash
usages to lhash2 and then retire listening_hash.

Since most changes need to be done together, it is hard to cut
the listening_hash to lhash2 switch into small patches.  The
changes in this patch is highlighted here for the review
purpose.

1. Because of the listening_hash removal, lhash2 can use the
   sk->sk_nulls_node instead of the icsk->icsk_listen_portaddr_node.
   This will also keep the sk_unhashed() check to work as is
   after stop adding sk to listening_hash.

   The union is removed from inet_listen_hashbucket because
   only nulls_head is needed.

2. icsk->icsk_listen_portaddr_node and its helpers are removed.

3. The current lhash2 users needs to iterate with sk_nulls_node
   instead of icsk_listen_portaddr_node.

   One case is in the inet[6]_lhash2_lookup().

   Another case is the seq_file iterator in tcp_ipv4.c.
   One thing to note is sk_nulls_next() is needed
   because the old inet_lhash2_for_each_icsk_continue()
   does a "next" first before iterating.

4. Move the remaining listening_hash usage to lhash2

   inet_reuseport_add_sock() which this series is
   trying to improve.

   inet_diag.c and mptcp_diag.c are the final two
   remaining use cases and is moved to lhash2 now also.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-05-12 16:52:18 -07:00
Eric Dumazet 68822bdf76 net: generalize skb freeing deferral to per-cpu lists
Logic added in commit f35f821935 ("tcp: defer skb freeing after socket
lock is released") helped bulk TCP flows to move the cost of skbs
frees outside of critical section where socket lock was held.

But for RPC traffic, or hosts with RFS enabled, the solution is far from
being ideal.

For RPC traffic, recvmsg() has to return to user space right after
skb payload has been consumed, meaning that BH handler has no chance
to pick the skb before recvmsg() thread. This issue is more visible
with BIG TCP, as more RPC fit one skb.

For RFS, even if BH handler picks the skbs, they are still picked
from the cpu on which user thread is running.

Ideally, it is better to free the skbs (and associated page frags)
on the cpu that originally allocated them.

This patch removes the per socket anchor (sk->defer_list) and
instead uses a per-cpu list, which will hold more skbs per round.

This new per-cpu list is drained at the end of net_action_rx(),
after incoming packets have been processed, to lower latencies.

In normal conditions, skbs are added to the per-cpu list with
no further action. In the (unlikely) cases where the cpu does not
run net_action_rx() handler fast enough, we use an IPI to raise
NET_RX_SOFTIRQ on the remote cpu.

Also, we do not bother draining the per-cpu list from dev_cpu_dead()
This is because skbs in this list have no requirement on how fast
they should be freed.

Note that we can add in the future a small per-cpu cache
if we see any contention on sd->defer_lock.

Tested on a pair of hosts with 100Gbit NIC, RFS enabled,
and /proc/sys/net/ipv4/tcp_rmem[2] tuned to 16MB to work around
page recycling strategy used by NIC driver (its page pool capacity
being too small compared to number of skbs/pages held in sockets
receive queues)

Note that this tuning was only done to demonstrate worse
conditions for skb freeing for this particular test.
These conditions can happen in more general production workload.

10 runs of one TCP_STREAM flow

Before:
Average throughput: 49685 Mbit.

Kernel profiles on cpu running user thread recvmsg() show high cost for
skb freeing related functions (*)

    57.81%  [kernel]       [k] copy_user_enhanced_fast_string
(*) 12.87%  [kernel]       [k] skb_release_data
(*)  4.25%  [kernel]       [k] __free_one_page
(*)  3.57%  [kernel]       [k] __list_del_entry_valid
     1.85%  [kernel]       [k] __netif_receive_skb_core
     1.60%  [kernel]       [k] __skb_datagram_iter
(*)  1.59%  [kernel]       [k] free_unref_page_commit
(*)  1.16%  [kernel]       [k] __slab_free
     1.16%  [kernel]       [k] _copy_to_iter
(*)  1.01%  [kernel]       [k] kfree
(*)  0.88%  [kernel]       [k] free_unref_page
     0.57%  [kernel]       [k] ip6_rcv_core
     0.55%  [kernel]       [k] ip6t_do_table
     0.54%  [kernel]       [k] flush_smp_call_function_queue
(*)  0.54%  [kernel]       [k] free_pcppages_bulk
     0.51%  [kernel]       [k] llist_reverse_order
     0.38%  [kernel]       [k] process_backlog
(*)  0.38%  [kernel]       [k] free_pcp_prepare
     0.37%  [kernel]       [k] tcp_recvmsg_locked
(*)  0.37%  [kernel]       [k] __list_add_valid
     0.34%  [kernel]       [k] sock_rfree
     0.34%  [kernel]       [k] _raw_spin_lock_irq
(*)  0.33%  [kernel]       [k] __page_cache_release
     0.33%  [kernel]       [k] tcp_v6_rcv
(*)  0.33%  [kernel]       [k] __put_page
(*)  0.29%  [kernel]       [k] __mod_zone_page_state
     0.27%  [kernel]       [k] _raw_spin_lock

After patch:
Average throughput: 73076 Mbit.

Kernel profiles on cpu running user thread recvmsg() looks better:

    81.35%  [kernel]       [k] copy_user_enhanced_fast_string
     1.95%  [kernel]       [k] _copy_to_iter
     1.95%  [kernel]       [k] __skb_datagram_iter
     1.27%  [kernel]       [k] __netif_receive_skb_core
     1.03%  [kernel]       [k] ip6t_do_table
     0.60%  [kernel]       [k] sock_rfree
     0.50%  [kernel]       [k] tcp_v6_rcv
     0.47%  [kernel]       [k] ip6_rcv_core
     0.45%  [kernel]       [k] read_tsc
     0.44%  [kernel]       [k] _raw_spin_lock_irqsave
     0.37%  [kernel]       [k] _raw_spin_lock
     0.37%  [kernel]       [k] native_irq_return_iret
     0.33%  [kernel]       [k] __inet6_lookup_established
     0.31%  [kernel]       [k] ip6_protocol_deliver_rcu
     0.29%  [kernel]       [k] tcp_rcv_established
     0.29%  [kernel]       [k] llist_reverse_order

v2: kdoc issue (kernel bots)
    do not defer if (alloc_cpu == smp_processor_id()) (Paolo)
    replace the sk_buff_head with a single-linked list (Jakub)
    add a READ_ONCE()/WRITE_ONCE() for the lockless read of sd->defer_list

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20220422201237.416238-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-04-26 17:05:59 -07:00
Guillaume Nault 67e1e2f485 ipv4: Avoid using RTO_ONLINK with ip_route_connect().
Now that ip_rt_fix_tos() doesn't reset ->flowi4_scope unconditionally,
we don't have to rely on the RTO_ONLINK bit to properly set the scope
of a flowi4 structure. We can just set ->flowi4_scope explicitly and
avoid using RTO_ONLINK in ->flowi4_tos.

This patch converts callers of ip_route_connect(). Instead of setting
the tos parameter with RT_CONN_FLAGS(sk), as all callers do, we can:

  1- Drop the tos parameter from ip_route_connect(): its value was
     entirely based on sk, which is also passed as parameter.

  2- Set ->flowi4_scope depending on the SOCK_LOCALROUTE socket option
     instead of always initialising it with RT_SCOPE_UNIVERSE (let's
     define ip_sock_rt_scope() for this purpose).

  3- Avoid overloading ->flowi4_tos with RTO_ONLINK: since the scope is
     now properly initialised, we don't need to tell ip_rt_fix_tos() to
     adjust ->flowi4_scope for us. So let's define ip_sock_rt_tos(),
     which is the same as RT_CONN_FLAGS() but without the RTO_ONLINK
     bit overload.

Note:
  In the original ip_route_connect() code, __ip_route_output_key()
  might clear the RTO_ONLINK bit of fl4->flowi4_tos (because of
  ip_rt_fix_tos()). Therefore flowi4_update_output() had to reuse the
  original tos variable. Now that we don't set RTO_ONLINK any more,
  this is not a problem and we can use fl4->flowi4_tos in
  flowi4_update_output().

Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-04-22 13:06:03 +01:00
Eric Dumazet 4057037535 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 8b8a321ff7 ("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>
2022-04-06 12:05:41 -07:00
Eric Dumazet 65466904b0 tcp: adjust TSO packet sizes based on min_rtt
Back when tcp_tso_autosize() and TCP pacing were introduced,
our focus was really to reduce burst sizes for long distance
flows.

The simple heuristic of using sk_pacing_rate/1024 has worked
well, but can lead to too small packets for hosts in the same
rack/cluster, when thousands of flows compete for the bottleneck.

Neal Cardwell had the idea of making the TSO burst size
a function of both sk_pacing_rate and tcp_min_rtt()

Indeed, for local flows, sending bigger bursts is better
to reduce cpu costs, as occasional losses can be repaired
quite fast.

This patch is based on Neal Cardwell implementation
done more than two years ago.
bbr is adjusting max_pacing_rate based on measured bandwidth,
while cubic would over estimate max_pacing_rate.

/proc/sys/net/ipv4/tcp_tso_rtt_log can be used to tune or disable
this new feature, in logarithmic steps.

Tested:

100Gbit NIC, two hosts in the same rack, 4K MTU.
600 flows rate-limited to 20000000 bytes per second.

Before patch: (TSO sizes would be limited to 20000000/1024/4096 -> 4 segments per TSO)

~# echo 0 >/proc/sys/net/ipv4/tcp_tso_rtt_log
~# nstat -n;perf stat ./super_netperf 600 -H otrv6 -l 20 -- -K dctcp -q 20000000;nstat|egrep "TcpInSegs|TcpOutSegs|TcpRetransSegs|Delivered"
  96005

 Performance counter stats for './super_netperf 600 -H otrv6 -l 20 -- -K dctcp -q 20000000':

         65,945.29 msec task-clock                #    2.845 CPUs utilized
         1,314,632      context-switches          # 19935.279 M/sec
             5,292      cpu-migrations            #   80.249 M/sec
           940,641      page-faults               # 14264.023 M/sec
   201,117,030,926      cycles                    # 3049769.216 GHz                   (83.45%)
    17,699,435,405      stalled-cycles-frontend   #    8.80% frontend cycles idle     (83.48%)
   136,584,015,071      stalled-cycles-backend    #   67.91% backend cycles idle      (83.44%)
    53,809,530,436      instructions              #    0.27  insn per cycle
                                                  #    2.54  stalled cycles per insn  (83.36%)
     9,062,315,523      branches                  # 137422329.563 M/sec               (83.22%)
       153,008,621      branch-misses             #    1.69% of all branches          (83.32%)

      23.182970846 seconds time elapsed

TcpInSegs                       15648792           0.0
TcpOutSegs                      58659110           0.0  # Average of 3.7 4K segments per TSO packet
TcpExtTCPDelivered              58654791           0.0
TcpExtTCPDeliveredCE            19                 0.0

After patch:

~# echo 9 >/proc/sys/net/ipv4/tcp_tso_rtt_log
~# nstat -n;perf stat ./super_netperf 600 -H otrv6 -l 20 -- -K dctcp -q 20000000;nstat|egrep "TcpInSegs|TcpOutSegs|TcpRetransSegs|Delivered"
  96046

 Performance counter stats for './super_netperf 600 -H otrv6 -l 20 -- -K dctcp -q 20000000':

         48,982.58 msec task-clock                #    2.104 CPUs utilized
           186,014      context-switches          # 3797.599 M/sec
             3,109      cpu-migrations            #   63.472 M/sec
           941,180      page-faults               # 19214.814 M/sec
   153,459,763,868      cycles                    # 3132982.807 GHz                   (83.56%)
    12,069,861,356      stalled-cycles-frontend   #    7.87% frontend cycles idle     (83.32%)
   120,485,917,953      stalled-cycles-backend    #   78.51% backend cycles idle      (83.24%)
    36,803,672,106      instructions              #    0.24  insn per cycle
                                                  #    3.27  stalled cycles per insn  (83.18%)
     5,947,266,275      branches                  # 121417383.427 M/sec               (83.64%)
        87,984,616      branch-misses             #    1.48% of all branches          (83.43%)

      23.281200256 seconds time elapsed

TcpInSegs                       1434706            0.0
TcpOutSegs                      58883378           0.0  # Average of 41 4K segments per TSO packet
TcpExtTCPDelivered              58878971           0.0
TcpExtTCPDeliveredCE            9664               0.0

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Link: https://lore.kernel.org/r/20220309015757.2532973-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-03-09 20:05:44 -08:00
Jakub Kicinski 1330b6ef33 skb: make drop reason booleanable
We have a number of cases where function returns drop/no drop
decision as a boolean. Now that we want to report the reason
code as well we have to pass extra output arguments.

We can make the reason code evaluate correctly as bool.

I believe we're good to reorder the reasons as they are
reported to user space as strings.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-03-09 11:22:58 +00:00
Dmitry Safonov 7bbb765b73 net/tcp: Merge TCP-MD5 inbound callbacks
The functions do essentially the same work to verify TCP-MD5 sign.
Code can be merged into one family-independent function in order to
reduce copy'n'paste and generated code.
Later with TCP-AO option added, this will allow to create one function
that's responsible for segment verification, that will have all the
different checks for MD5/AO/non-signed packets, which in turn will help
to see checks for all corner-cases in one function, rather than spread
around different families and functions.

Cc: Eric Dumazet <edumazet@google.com>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20220223175740.452397-1-dima@arista.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-02-24 21:43:53 -08:00
Menglong Dong 8eba65fa5f net: tcp: use kfree_skb_reason() for tcp_v{4,6}_do_rcv()
Replace kfree_skb() used in tcp_v4_do_rcv() and tcp_v6_do_rcv() with
kfree_skb_reason().

Reviewed-by: Mengen Sun <mengensun@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-02-20 13:55:31 +00:00
Menglong Dong 7a26dc9e7b net: tcp: add skb drop reasons to tcp_add_backlog()
Pass the address of drop_reason to tcp_add_backlog() to store the
reasons for skb drops when fails. Following drop reasons are
introduced:

SKB_DROP_REASON_SOCKET_BACKLOG

Reviewed-by: Mengen Sun <mengensun@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-02-20 13:55:31 +00:00
Menglong Dong 643b622b51 net: tcp: add skb drop reasons to tcp_v{4,6}_inbound_md5_hash()
Pass the address of drop reason to tcp_v4_inbound_md5_hash() and
tcp_v6_inbound_md5_hash() to store the reasons for skb drops when this
function fails. Therefore, the drop reason can be passed to
kfree_skb_reason() when the skb needs to be freed.

Following drop reasons are added:

SKB_DROP_REASON_TCP_MD5NOTFOUND
SKB_DROP_REASON_TCP_MD5UNEXPECTED
SKB_DROP_REASON_TCP_MD5FAILURE

SKB_DROP_REASON_TCP_MD5* above correspond to LINUX_MIB_TCPMD5*

Reviewed-by: Mengen Sun <mengensun@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-02-20 13:55:31 +00:00