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DCCP is going away soon, and had no twsk_unique() method.
We can directly call tcp_twsk_unique() for TCP sockets.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240507164140.940547-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
"struct net_protocol" has a 32bit hole in 32bit arches.
Use it to store the 32bit secret used by UDP and TCP,
to increase cache locality in rx path.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20240306160031.874438-15-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Now all sockets including TIME_WAIT are linked to bhash2 using
sock_common.skc_bind_node.
We no longer use inet_bind2_bucket.deathrow, sock.sk_bind2_node,
and inet_timewait_sock.tw_bind2_node.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Now we can use sk_bind_node/tw_bind_node for bhash2, which means
we need not link TIME_WAIT sockets separately.
The dead code and sk_bind2_node will be removed in the next patch.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Now we do not use tb->owners and can unlink sockets from bhash.
sk_bind_node/tw_bind_node are available for bhash2 and will be
used in the following patch.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
We use hlist_empty(&tb->owners) to check if the bhash bucket has a socket.
We can check the child bhash2 buckets instead.
For this to work, the bhash2 bucket must be freed before the bhash bucket.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
bhash2 added a new member sk_bind2_node in struct sock to link
sockets to bhash2 in addition to bhash.
bhash is still needed to search conflicting sockets efficiently
from a port for the wildcard address. However, bhash itself need
not have sockets.
If we link each bhash2 bucket to the corresponding bhash bucket,
we can iterate the same set of the sockets from bhash2 via bhash.
This patch links bhash2 to bhash only, and the actual use will be
in the later patches. Finally, we will remove sk_bind2_node.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Later, we no longer link sockets to bhash. Instead, each bhash2
bucket is linked to the corresponding bhash bucket.
Then, we pass the bhash bucket to bhash2 allocation functions as
tb. However, tb is already used in inet_bind2_bucket_create() and
inet_bind2_bucket_init() as the bhash2 bucket.
To make the following diff clear, let's use tb2 for the bhash2 bucket
there.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
inet_bind2_bucket_addr_match() and inet_bind2_bucket_match_addr_any()
are called for each bhash2 bucket to check conflicts. Thus, we call
ipv6_addr_any() and ipv6_addr_v4mapped() over and over during bind().
Let's avoid calling them by saving the address type in inet_bind2_bucket.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In bhash2, IPv4/IPv6 addresses are saved in two union members,
which complicate address checks in inet_bind2_bucket_addr_match()
and inet_bind2_bucket_match_addr_any() considering uninitialised
memory and v4-mapped-v6 conflicts.
Let's simplify that by saving IPv4 address as v4-mapped-v6 address
and defining tb2.rcv_saddr as tb2.v6_rcv_saddr.s6_addr32[3].
Then, we can compare v6 address as is, and after checking v4-mapped-v6,
we can compare v4 address easily. Also, we can remove tb2->family.
Note these functions will be further refactored in the next patch.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The protocol family tests in inet_bind2_bucket_addr_match() and
inet_bind2_bucket_match_addr_any() are ordered as follows.
if (sk->sk_family != tb2->family)
else if (sk->sk_family == AF_INET6)
else
This patch rearranges them so that AF_INET6 socket is handled first
to make the following patch tidy, where tb2->family will be removed.
if (sk->sk_family == AF_INET6)
else if (tb2->family == AF_INET6)
else
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
While checking port availability in bind() or listen(), we used only
bhash for all v4-mapped-v6 addresses. But there is no good reason not
to use bhash2 for v4-mapped-v6 non-wildcard addresses.
Let's do it by returning true in inet_use_bhash2_on_bind(). Then, we
also need to add a test in inet_bind2_bucket_match_addr_any() so that
::ffff:X.X.X.X will match with 0.0.0.0.
Note that sk->sk_rcv_saddr is initialised for v4-mapped-v6 sk in
__inet6_bind().
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In commit 1580ab63fc ("tcp/dccp: better use of ephemeral ports in connect()")
we added an heuristic to select even ports for connect() and odd ports for bind().
This was nice because no applications changes were needed.
But it added more costs when all even ports are in use,
when there are few listeners and many active connections.
Since then, IP_LOCAL_PORT_RANGE has been added to permit an application
to partition ephemeral port range at will.
This patch extends the idea so that if IP_LOCAL_PORT_RANGE is set on
a socket before accept(), port selection no longer favors even ports.
This means that connect() can find a suitable source port faster,
and applications can use a different split between connect() and bind()
users.
This should give more entropy to Toeplitz hash used in RSS: Using even
ports was wasting one bit from the 16bit sport.
A similar change can be done in inet_csk_find_open_port() if needed.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Link: https://lore.kernel.org/r/20231214192939.1962891-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
We've started to see the following kernel traces:
WARNING: CPU: 83 PID: 0 at net/core/filter.c:6641 sk_lookup+0x1bd/0x1d0
Call Trace:
<IRQ>
__bpf_skc_lookup+0x10d/0x120
bpf_sk_lookup+0x48/0xd0
bpf_sk_lookup_tcp+0x19/0x20
bpf_prog_<redacted>+0x37c/0x16a3
cls_bpf_classify+0x205/0x2e0
tcf_classify+0x92/0x160
__netif_receive_skb_core+0xe52/0xf10
__netif_receive_skb_list_core+0x96/0x2b0
napi_complete_done+0x7b5/0xb70
<redacted>_poll+0x94/0xb0
net_rx_action+0x163/0x1d70
__do_softirq+0xdc/0x32e
asm_call_irq_on_stack+0x12/0x20
</IRQ>
do_softirq_own_stack+0x36/0x50
do_softirq+0x44/0x70
__inet_hash can race with lockless (rcu) readers on the other cpus:
__inet_hash
__sk_nulls_add_node_rcu
<- (bpf triggers here)
sock_set_flag(SOCK_RCU_FREE)
Let's move the SOCK_RCU_FREE part up a bit, before we are inserting
the socket into hashtables. Note, that the race is really harmless;
the bpf callers are handling this situation (where listener socket
doesn't have SOCK_RCU_FREE set) correctly, so the only
annoyance is a WARN_ONCE.
More details from Eric regarding SOCK_RCU_FREE timeline:
Commit 3b24d854cb ("tcp/dccp: do not touch listener sk_refcnt under
synflood") added SOCK_RCU_FREE. At that time, the precise location of
sock_set_flag(sk, SOCK_RCU_FREE) did not matter, because the thread calling
__inet_hash() owns a reference on sk. SOCK_RCU_FREE was only tested
at dismantle time.
Commit 6acc9b432e ("bpf: Add helper to retrieve socket in BPF")
started checking SOCK_RCU_FREE _after_ the lookup to infer whether
the refcount has been taken care of.
Fixes: 6acc9b432e ("bpf: Add helper to retrieve socket in BPF")
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
syzbot reported a warning [0] introduced by commit c48ef9c4ae ("tcp: Fix
bind() regression for v4-mapped-v6 non-wildcard address.").
After the cited commit, a v4 socket's address matches the corresponding
v4-mapped-v6 tb2 in inet_bind2_bucket_match_addr(), not vice versa.
During X.X.X.X -> ::ffff:X.X.X.X order bind()s, the second bind() uses
bhash and conflicts properly without checking bhash2 so that we need not
check if a v4-mapped-v6 sk matches the corresponding v4 address tb2 in
inet_bind2_bucket_match_addr(). However, the repro shows that we need
to check that in a no-conflict case.
The repro bind()s two sockets to the 2-tuples using SO_REUSEPORT and calls
listen() for the first socket:
from socket import *
s1 = socket()
s1.setsockopt(SOL_SOCKET, SO_REUSEPORT, 1)
s1.bind(('127.0.0.1', 0))
s2 = socket(AF_INET6)
s2.setsockopt(SOL_SOCKET, SO_REUSEPORT, 1)
s2.bind(('::ffff:127.0.0.1', s1.getsockname()[1]))
s1.listen()
The second socket should belong to the first socket's tb2, but the second
bind() creates another tb2 bucket because inet_bind2_bucket_find() returns
NULL in inet_csk_get_port() as the v4-mapped-v6 sk does not match the
corresponding v4 address tb2.
bhash2[] -> tb2(::ffff:X.X.X.X) -> tb2(X.X.X.X)
Then, listen() for the first socket calls inet_csk_get_port(), where the
v4 address matches the v4-mapped-v6 tb2 and WARN_ON() is triggered.
To avoid that, we need to check if v4-mapped-v6 sk address matches with
the corresponding v4 address tb2 in inet_bind2_bucket_match().
The same checks are needed in inet_bind2_bucket_addr_match() too, so we
can move all checks there and call it from inet_bind2_bucket_match().
Note that now tb->family is just an address family of tb->(v6_)?rcv_saddr
and not of sockets in the bucket. This could be refactored later by
defining tb->rcv_saddr as tb->v6_rcv_saddr.s6_addr32[3] and prepending
::ffff: when creating v4 tb2.
[0]:
WARNING: CPU: 0 PID: 5049 at net/ipv4/inet_connection_sock.c:587 inet_csk_get_port+0xf96/0x2350 net/ipv4/inet_connection_sock.c:587
Modules linked in:
CPU: 0 PID: 5049 Comm: syz-executor288 Not tainted 6.6.0-rc2-syzkaller-00018-g2cf0f7156238 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
RIP: 0010:inet_csk_get_port+0xf96/0x2350 net/ipv4/inet_connection_sock.c:587
Code: 7c 24 08 e8 4c b6 8a 01 31 d2 be 88 01 00 00 48 c7 c7 e0 94 ae 8b e8 59 2e a3 f8 2e 2e 2e 31 c0 e9 04 fe ff ff e8 ca 88 d0 f8 <0f> 0b e9 0f f9 ff ff e8 be 88 d0 f8 49 8d 7e 48 e8 65 ca 5a 00 31
RSP: 0018:ffffc90003abfbf0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff888026429100 RCX: 0000000000000000
RDX: ffff88807edcbb80 RSI: ffffffff88b73d66 RDI: ffff888026c49f38
RBP: ffff888026c49f30 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff9260f200
R13: ffff888026c49880 R14: 0000000000000000 R15: ffff888026429100
FS: 00005555557d5380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000045ad50 CR3: 0000000025754000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
inet_csk_listen_start+0x155/0x360 net/ipv4/inet_connection_sock.c:1256
__inet_listen_sk+0x1b8/0x5c0 net/ipv4/af_inet.c:217
inet_listen+0x93/0xd0 net/ipv4/af_inet.c:239
__sys_listen+0x194/0x270 net/socket.c:1866
__do_sys_listen net/socket.c:1875 [inline]
__se_sys_listen net/socket.c:1873 [inline]
__x64_sys_listen+0x53/0x80 net/socket.c:1873
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f3a5bce3af9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 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 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc1a1c79e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000032
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f3a5bce3af9
RDX: 00007f3a5bce3af9 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f3a5bd565f0 R08: 0000000000000006 R09: 0000000000000006
R10: 0000000000000006 R11: 0000000000000246 R12: 0000000000000001
R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001
</TASK>
Fixes: c48ef9c4ae ("tcp: Fix bind() regression for v4-mapped-v6 non-wildcard address.")
Reported-by: syzbot+71e724675ba3958edb31@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=71e724675ba3958edb31
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20231010013814.70571-1-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Since bhash2 was introduced, the example below does not work as expected.
These two bind() should conflict, but the 2nd bind() now succeeds.
from socket import *
s1 = socket(AF_INET6, SOCK_STREAM)
s1.bind(('::ffff:127.0.0.1', 0))
s2 = socket(AF_INET, SOCK_STREAM)
s2.bind(('127.0.0.1', s1.getsockname()[1]))
During the 2nd bind() in inet_csk_get_port(), inet_bind2_bucket_find()
fails to find the 1st socket's tb2, so inet_bind2_bucket_create() allocates
a new tb2 for the 2nd socket. Then, we call inet_csk_bind_conflict() that
checks conflicts in the new tb2 by inet_bhash2_conflict(). However, the
new tb2 does not include the 1st socket, thus the bind() finally succeeds.
In this case, inet_bind2_bucket_match() must check if AF_INET6 tb2 has
the conflicting v4-mapped-v6 address so that inet_bind2_bucket_find()
returns the 1st socket's tb2.
Note that if we bind two sockets to 127.0.0.1 and then ::FFFF:127.0.0.1,
the 2nd bind() fails properly for the same reason mentinoed in the previous
commit.
Fixes: 28044fc1d4 ("net: Add a bhash2 table hashed by port and address")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Andrei Vagin reported bind() regression with strace logs.
If we bind() a TCPv6 socket to ::FFFF:0.0.0.0 and then bind() a TCPv4
socket to 127.0.0.1, the 2nd bind() should fail but now succeeds.
from socket import *
s1 = socket(AF_INET6, SOCK_STREAM)
s1.bind(('::ffff:0.0.0.0', 0))
s2 = socket(AF_INET, SOCK_STREAM)
s2.bind(('127.0.0.1', s1.getsockname()[1]))
During the 2nd bind(), if tb->family is AF_INET6 and sk->sk_family is
AF_INET in inet_bind2_bucket_match_addr_any(), we still need to check
if tb has the v4-mapped-v6 wildcard address.
The example above does not work after commit 5456262d2b ("net: Fix
incorrect address comparison when searching for a bind2 bucket"), but
the blamed change is not the commit.
Before the commit, the leading zeros of ::FFFF:0.0.0.0 were treated
as 0.0.0.0, and the sequence above worked by chance. Technically, this
case has been broken since bhash2 was introduced.
Note that if we bind() two sockets to 127.0.0.1 and then ::FFFF:0.0.0.0,
the 2nd bind() fails properly because we fall back to using bhash to
detect conflicts for the v4-mapped-v6 address.
Fixes: 28044fc1d4 ("net: Add a bhash2 table hashed by port and address")
Reported-by: Andrei Vagin <avagin@google.com>
Closes: https://lore.kernel.org/netdev/ZPuYBOFC8zsK6r9T@google.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This is a prep patch to make the following patches cleaner that touch
inet_bind2_bucket_match() and inet_bind2_bucket_match_addr_any().
Both functions have duplicated comparison for netns, port, and l3mdev.
Let's factorise them.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
There are already INDIRECT_CALLABLE_DECLARE in the hashtable
headers, no need to declare them again.
Fixes: 0f495f7617 ("net: remove duplicate reuseport_lookup functions")
Suggested-by: Martin Lau <martin.lau@linux.dev>
Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230731-indir-call-v1-1-4cd0aeaee64f@isovalent.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Now that inet[6]_lookup_reuseport are parameterised on the ehashfn
we can remove two sk_lookup helpers.
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
Link: https://lore.kernel.org/r/20230720-so-reuseport-v6-6-7021b683cdae@isovalent.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
The current implementation was extracted from inet[6]_lhash2_lookup
in commit 80b373f74f ("inet: Extract helper for selecting socket
from reuseport group") and commit 5df6531292 ("inet6: Extract helper
for selecting socket from reuseport group"). In the original context,
sk is always in TCP_LISTEN state and so did not have a separate check.
Add documentation that specifies which sk_state are valid to pass to
the function.
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
Link: https://lore.kernel.org/r/20230720-so-reuseport-v6-5-7021b683cdae@isovalent.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
There are currently four copies of reuseport_lookup: one each for
(TCP, UDP)x(IPv4, IPv6). This forces us to duplicate all callers of
those functions as well. This is already the case for sk_lookup
helpers (inet,inet6,udp4,udp6)_lookup_run_bpf.
There are two differences between the reuseport_lookup helpers:
1. They call different hash functions depending on protocol
2. UDP reuseport_lookup checks that sk_state != TCP_ESTABLISHED
Move the check for sk_state into the caller and use the INDIRECT_CALL
infrastructure to cut down the helpers to one per IP version.
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
Link: https://lore.kernel.org/r/20230720-so-reuseport-v6-4-7021b683cdae@isovalent.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Rename the existing reuseport helpers for IPv4 and IPv6 so that they
can be invoked in the follow up commit. Export them so that building
DCCP and IPv6 as a module works.
No change in functionality.
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
Link: https://lore.kernel.org/r/20230720-so-reuseport-v6-3-7021b683cdae@isovalent.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
This reverts commit 3f4ca5fafc.
Commit 3f4ca5fafc ("tcp: avoid the lookup process failing to get sk in
ehash table") reversed the order in how a socket is inserted into ehash
to fix an issue that ehash-lookup could fail when reqsk/full sk/twsk are
swapped. However, it introduced another lookup failure.
The full socket in ehash is allocated from a slab with SLAB_TYPESAFE_BY_RCU
and does not have SOCK_RCU_FREE, so the socket could be reused even while
it is being referenced on another CPU doing RCU lookup.
Let's say a socket is reused and inserted into the same hash bucket during
lookup. After the blamed commit, a new socket is inserted at the end of
the list. If that happens, we will skip sockets placed after the previous
position of the reused socket, resulting in ehash lookup failure.
As described in Documentation/RCU/rculist_nulls.rst, we should insert a
new socket at the head of the list to avoid such an issue.
This issue, the swap-lookup-failure, and another variant reported in [0]
can all be handled properly by adding a locked ehash lookup suggested by
Eric Dumazet [1].
However, this issue could occur for every packet, thus more likely than
the other two races, so let's revert the change for now.
Link: https://lore.kernel.org/netdev/20230606064306.9192-1-duanmuquan@baidu.com/ [0]
Link: https://lore.kernel.org/netdev/CANn89iK8snOz8TYOhhwfimC7ykYA78GA3Nyv8x06SZYa1nKdyA@mail.gmail.com/ [1]
Fixes: 3f4ca5fafc ("tcp: avoid the lookup process failing to get sk in ehash table")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230717215918.15723-1-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Some code defines the IPv6 wildcard address as a local variable and
use it with memcmp() or ipv6_addr_equal().
Let's use in6addr_any and ipv6_addr_any() instead.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Paul Holzinger reported [0] that commit 5456262d2b ("net: Fix
incorrect address comparison when searching for a bind2 bucket")
introduced a bind() regression. Paul also gave a nice repro that
calls two types of bind() on the same port, both of which now
succeed, but the second call should fail:
bind(fd1, ::, port) + bind(fd2, 127.0.0.1, port)
The cited commit added address family tests in three functions to
fix the uninit-value KMSAN report. [1] However, the test added to
inet_bind2_bucket_match_addr_any() removed a necessary conflict
check; the dual-stack wildcard address no longer conflicts with
an IPv4 non-wildcard address.
If tb->family is AF_INET6 and sk->sk_family is AF_INET in
inet_bind2_bucket_match_addr_any(), we still need to check
if tb has the dual-stack wildcard address.
Note that the IPv4 wildcard address does not conflict with
IPv6 non-wildcard addresses.
[0]: https://lore.kernel.org/netdev/e21bf153-80b0-9ec0-15ba-e04a4ad42c34@redhat.com/
[1]: https://lore.kernel.org/netdev/CAG_fn=Ud3zSW7AZWXc+asfMhZVL5ETnvuY44Pmyv4NPv-ijN-A@mail.gmail.com/
Fixes: 5456262d2b ("net: Fix incorrect address comparison when searching for a bind2 bucket")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reported-by: Paul Holzinger <pholzing@redhat.com>
Link: https://lore.kernel.org/netdev/CAG_fn=Ud3zSW7AZWXc+asfMhZVL5ETnvuY44Pmyv4NPv-ijN-A@mail.gmail.com/
Reviewed-by: Eric Dumazet <edumazet@google.com>
Tested-by: Paul Holzinger <pholzing@redhat.com>
Reviewed-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Users who want to share a single public IP address for outgoing connections
between several hosts traditionally reach for SNAT. However, SNAT requires
state keeping on the node(s) performing the NAT.
A stateless alternative exists, where a single IP address used for egress
can be shared between several hosts by partitioning the available ephemeral
port range. In such a setup:
1. Each host gets assigned a disjoint range of ephemeral ports.
2. Applications open connections from the host-assigned port range.
3. Return traffic gets routed to the host based on both, the destination IP
and the destination port.
An application which wants to open an outgoing connection (connect) from a
given port range today can choose between two solutions:
1. Manually pick the source port by bind()'ing to it before connect()'ing
the socket.
This approach has a couple of downsides:
a) Search for a free port has to be implemented in the user-space. If
the chosen 4-tuple happens to be busy, the application needs to retry
from a different local port number.
Detecting if 4-tuple is busy can be either easy (TCP) or hard
(UDP). In TCP case, the application simply has to check if connect()
returned an error (EADDRNOTAVAIL). That is assuming that the local
port sharing was enabled (REUSEADDR) by all the sockets.
# Assume desired local port range is 60_000-60_511
s = socket(AF_INET, SOCK_STREAM)
s.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
s.bind(("192.0.2.1", 60_000))
s.connect(("1.1.1.1", 53))
# Fails only if 192.0.2.1:60000 -> 1.1.1.1:53 is busy
# Application must retry with another local port
In case of UDP, the network stack allows binding more than one socket
to the same 4-tuple, when local port sharing is enabled
(REUSEADDR). Hence detecting the conflict is much harder and involves
querying sock_diag and toggling the REUSEADDR flag [1].
b) For TCP, bind()-ing to a port within the ephemeral port range means
that no connecting sockets, that is those which leave it to the
network stack to find a free local port at connect() time, can use
the this port.
IOW, the bind hash bucket tb->fastreuse will be 0 or 1, and the port
will be skipped during the free port search at connect() time.
2. Isolate the app in a dedicated netns and use the use the per-netns
ip_local_port_range sysctl to adjust the ephemeral port range bounds.
The per-netns setting affects all sockets, so this approach can be used
only if:
- there is just one egress IP address, or
- the desired egress port range is the same for all egress IP addresses
used by the application.
For TCP, this approach avoids the downsides of (1). Free port search and
4-tuple conflict detection is done by the network stack:
system("sysctl -w net.ipv4.ip_local_port_range='60000 60511'")
s = socket(AF_INET, SOCK_STREAM)
s.setsockopt(SOL_IP, IP_BIND_ADDRESS_NO_PORT, 1)
s.bind(("192.0.2.1", 0))
s.connect(("1.1.1.1", 53))
# Fails if all 4-tuples 192.0.2.1:60000-60511 -> 1.1.1.1:53 are busy
For UDP this approach has limited applicability. Setting the
IP_BIND_ADDRESS_NO_PORT socket option does not result in local source
port being shared with other connected UDP sockets.
Hence relying on the network stack to find a free source port, limits the
number of outgoing UDP flows from a single IP address down to the number
of available ephemeral ports.
To put it another way, partitioning the ephemeral port range between hosts
using the existing Linux networking API is cumbersome.
To address this use case, add a new socket option at the SOL_IP level,
named IP_LOCAL_PORT_RANGE. The new option can be used to clamp down the
ephemeral port range for each socket individually.
The option can be used only to narrow down the per-netns local port
range. If the per-socket range lies outside of the per-netns range, the
latter takes precedence.
UAPI-wise, the low and high range bounds are passed to the kernel as a pair
of u16 values in host byte order packed into a u32. This avoids pointer
passing.
PORT_LO = 40_000
PORT_HI = 40_511
s = socket(AF_INET, SOCK_STREAM)
v = struct.pack("I", PORT_HI << 16 | PORT_LO)
s.setsockopt(SOL_IP, IP_LOCAL_PORT_RANGE, v)
s.bind(("127.0.0.1", 0))
s.getsockname()
# Local address between ("127.0.0.1", 40_000) and ("127.0.0.1", 40_511),
# if there is a free port. EADDRINUSE otherwise.
[1] https://github.com/cloudflare/cloudflare-blog/blob/232b432c1d57/2022-02-connectx/connectx.py#L116
Reviewed-by: Marek Majkowski <marek@cloudflare.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
While one cpu is working on looking up the right socket from ehash
table, another cpu is done deleting the request socket and is about
to add (or is adding) the big socket from the table. It means that
we could miss both of them, even though it has little chance.
Let me draw a call trace map of the server side.
CPU 0 CPU 1
----- -----
tcp_v4_rcv() syn_recv_sock()
inet_ehash_insert()
-> sk_nulls_del_node_init_rcu(osk)
__inet_lookup_established()
-> __sk_nulls_add_node_rcu(sk, list)
Notice that the CPU 0 is receiving the data after the final ack
during 3-way shakehands and CPU 1 is still handling the final ack.
Why could this be a real problem?
This case is happening only when the final ack and the first data
receiving by different CPUs. Then the server receiving data with
ACK flag tries to search one proper established socket from ehash
table, but apparently it fails as my map shows above. After that,
the server fetches a listener socket and then sends a RST because
it finds a ACK flag in the skb (data), which obeys RST definition
in RFC 793.
Besides, Eric pointed out there's one more race condition where it
handles tw socket hashdance. Only by adding to the tail of the list
before deleting the old one can we avoid the race if the reader has
already begun the bucket traversal and it would possibly miss the head.
Many thanks to Eric for great help from beginning to end.
Fixes: 5e0724d027 ("tcp/dccp: fix hashdance race for passive sessions")
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/lkml/20230112065336.41034-1-kerneljasonxing@gmail.com/
Link: https://lore.kernel.org/r/20230118015941.1313-1-kerneljasonxing@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
__inet_hash_connect() has a fast path taken if sk_head(&tb->owners) is
equal to the sk parameter.
sk_head() returns the hlist_entry() with respect to the sk_node field.
However entries in the tb->owners list are inserted with respect to the
sk_bind_node field with sk_add_bind_node().
Thus the check would never pass and the fast path never execute.
This fast path has never been executed or tested as this bug seems
to be present since commit 1da177e4c3 ("Linux-2.6.12-rc2"), thus
remove it to reduce code complexity.
Signed-off-by: Pietro Borrello <borrello@diag.uniroma1.it>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230112-inet_hash_connect_bind_head-v3-1-b591fd212b93@diag.uniroma1.it
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Jiri Slaby reported regression of bind() with a simple repro. [0]
The repro creates a TIME_WAIT socket and tries to bind() a new socket
with the same local address and port. Before commit 28044fc1d4 ("net:
Add a bhash2 table hashed by port and address"), the bind() failed with
-EADDRINUSE, but now it succeeds.
The cited commit should have put TIME_WAIT sockets into bhash2; otherwise,
inet_bhash2_conflict() misses TIME_WAIT sockets when validating bind()
requests if the address is not a wildcard one.
The straight option is to move sk_bind2_node from struct sock to struct
sock_common to add twsk to bhash2 as implemented as RFC. [1] However, the
binary layout change in the struct sock could affect performances moving
hot fields on different cachelines.
To avoid that, we add another TIME_WAIT list in inet_bind2_bucket and check
it while validating bind().
[0]: https://lore.kernel.org/netdev/6b971a4e-c7d8-411e-1f92-fda29b5b2fb9@kernel.org/
[1]: https://lore.kernel.org/netdev/20221221151258.25748-2-kuniyu@amazon.com/
Fixes: 28044fc1d4 ("net: Add a bhash2 table hashed by port and address")
Reported-by: Jiri Slaby <jirislaby@kernel.org>
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Merge tag 'random-6.2-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random
Pull random number generator updates from Jason Donenfeld:
- Replace prandom_u32_max() and various open-coded variants of it,
there is now a new family of functions that uses fast rejection
sampling to choose properly uniformly random numbers within an
interval:
get_random_u32_below(ceil) - [0, ceil)
get_random_u32_above(floor) - (floor, U32_MAX]
get_random_u32_inclusive(floor, ceil) - [floor, ceil]
Coccinelle was used to convert all current users of
prandom_u32_max(), as well as many open-coded patterns, resulting in
improvements throughout the tree.
I'll have a "late" 6.1-rc1 pull for you that removes the now unused
prandom_u32_max() function, just in case any other trees add a new
use case of it that needs to converted. According to linux-next,
there may be two trivial cases of prandom_u32_max() reintroductions
that are fixable with a 's/.../.../'. So I'll have for you a final
conversion patch doing that alongside the removal patch during the
second week.
This is a treewide change that touches many files throughout.
- More consistent use of get_random_canary().
- Updates to comments, documentation, tests, headers, and
simplification in configuration.
- The arch_get_random*_early() abstraction was only used by arm64 and
wasn't entirely useful, so this has been replaced by code that works
in all relevant contexts.
- The kernel will use and manage random seeds in non-volatile EFI
variables, refreshing a variable with a fresh seed when the RNG is
initialized. The RNG GUID namespace is then hidden from efivarfs to
prevent accidental leakage.
These changes are split into random.c infrastructure code used in the
EFI subsystem, in this pull request, and related support inside of
EFISTUB, in Ard's EFI tree. These are co-dependent for full
functionality, but the order of merging doesn't matter.
- Part of the infrastructure added for the EFI support is also used for
an improvement to the way vsprintf initializes its siphash key,
replacing an sleep loop wart.
- The hardware RNG framework now always calls its correct random.c
input function, add_hwgenerator_randomness(), rather than sometimes
going through helpers better suited for other cases.
- The add_latent_entropy() function has long been called from the fork
handler, but is a no-op when the latent entropy gcc plugin isn't
used, which is fine for the purposes of latent entropy.
But it was missing out on the cycle counter that was also being mixed
in beside the latent entropy variable. So now, if the latent entropy
gcc plugin isn't enabled, add_latent_entropy() will expand to a call
to add_device_randomness(NULL, 0), which adds a cycle counter,
without the absent latent entropy variable.
- The RNG is now reseeded from a delayed worker, rather than on demand
when used. Always running from a worker allows it to make use of the
CPU RNG on platforms like S390x, whose instructions are too slow to
do so from interrupts. It also has the effect of adding in new inputs
more frequently with more regularity, amounting to a long term
transcript of random values. Plus, it helps a bit with the upcoming
vDSO implementation (which isn't yet ready for 6.2).
- The jitter entropy algorithm now tries to execute on many different
CPUs, round-robining, in hopes of hitting even more memory latencies
and other unpredictable effects. It also will mix in a cycle counter
when the entropy timer fires, in addition to being mixed in from the
main loop, to account more explicitly for fluctuations in that timer
firing. And the state it touches is now kept within the same cache
line, so that it's assured that the different execution contexts will
cause latencies.
* tag 'random-6.2-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: (23 commits)
random: include <linux/once.h> in the right header
random: align entropy_timer_state to cache line
random: mix in cycle counter when jitter timer fires
random: spread out jitter callback to different CPUs
random: remove extraneous period and add a missing one in comments
efi: random: refresh non-volatile random seed when RNG is initialized
vsprintf: initialize siphash key using notifier
random: add back async readiness notifier
random: reseed in delayed work rather than on-demand
random: always mix cycle counter in add_latent_entropy()
hw_random: use add_hwgenerator_randomness() for early entropy
random: modernize documentation comment on get_random_bytes()
random: adjust comment to account for removed function
random: remove early archrandom abstraction
random: use random.trust_{bootloader,cpu} command line option only
stackprotector: actually use get_random_canary()
stackprotector: move get_random_canary() into stackprotector.h
treewide: use get_random_u32_inclusive() when possible
treewide: use get_random_u32_{above,below}() instead of manual loop
treewide: use get_random_u32_below() instead of deprecated function
...
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>
When we call inet_bhash2_update_saddr(), prev_saddr is always non-NULL.
Let's remove the unnecessary test.
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>
This is a simple mechanical transformation done by:
@@
expression E;
@@
- prandom_u32_max
+ get_random_u32_below
(E)
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Reviewed-by: SeongJae Park <sj@kernel.org> # for damon
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> # for infiniband
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> # for arm
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
On embedded systems with little memory and no relevant
security concerns, it is beneficial to reduce the size
of the table.
Reducing the size from 2^16 to 2^8 saves 255 KiB
of kernel RAM.
Makes the table size configurable as an expert option.
The size was previously increased from 2^8 to 2^16
in commit 4c2c8f03a5 ("tcp: increase source port perturb table to
2^16").
Signed-off-by: Gleb Mazovetskiy <glex.spb@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Rather than incurring a division or requesting too many random bytes for
the given range, use the prandom_u32_max() function, which only takes
the minimum required bytes from the RNG and avoids divisions. This was
done mechanically with this coccinelle script:
@basic@
expression E;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u64;
@@
(
- ((T)get_random_u32() % (E))
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ((E) - 1))
+ prandom_u32_max(E * XXX_MAKE_SURE_E_IS_POW2)
|
- ((u64)(E) * get_random_u32() >> 32)
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ~PAGE_MASK)
+ prandom_u32_max(PAGE_SIZE)
)
@multi_line@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
identifier RAND;
expression E;
@@
- RAND = get_random_u32();
... when != RAND
- RAND %= (E);
+ RAND = prandom_u32_max(E);
// 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))
// Add one to the literal.
@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 == 2**32 - 1 or value == 2**31 - 1 or value == 2**24 - 1 or value == 2**16 - 1 or value == 2**8 - 1:
print("Skipping 0x%x for cleanup elsewhere" % (value))
cocci.include_match(False)
elif value & (value + 1) != 0:
print("Skipping 0x%x because it's not a power of two minus one" % (value))
cocci.include_match(False)
elif literal.startswith('0x'):
coccinelle.RESULT = cocci.make_expr("0x%x" % (value + 1))
else:
coccinelle.RESULT = cocci.make_expr("%d" % (value + 1))
// Replace the literal mask with the calculated result.
@plus_one@
expression literal_mask.LITERAL;
position literal_mask.p;
expression add_one.RESULT;
identifier FUNC;
@@
- (FUNC()@p & (LITERAL))
+ prandom_u32_max(RESULT)
@collapse_ret@
type T;
identifier VAR;
expression E;
@@
{
- T VAR;
- VAR = (E);
- return VAR;
+ return E;
}
@drop_var@
type T;
identifier VAR;
@@
{
- T VAR;
... when != VAR
}
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: KP Singh <kpsingh@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz> # for ext4 and sbitmap
Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> # for drbd
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # for s390
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
The _SLOW designation wasn't really descriptive of anything. This is
meant to be called from process context when it's possible to sleep. So
name this more aptly _SLEEPABLE, which better fits its intended use.
Fixes: 62c07983be ("once: add DO_ONCE_SLOW() for sleepable contexts")
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20221003181413.1221968-1-Jason@zx2c4.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Christophe Leroy reported a ~80ms latency spike
happening at first TCP connect() time.
This is because __inet_hash_connect() uses get_random_once()
to populate a perturbation table which became quite big
after commit 4c2c8f03a5 ("tcp: increase source port perturb table to 2^16")
get_random_once() uses DO_ONCE(), which block hard irqs for the duration
of the operation.
This patch adds DO_ONCE_SLOW() which uses a mutex instead of a spinlock
for operations where we prefer to stay in process context.
Then __inet_hash_connect() can use get_random_slow_once()
to populate its perturbation table.
Fixes: 4c2c8f03a5 ("tcp: increase source port perturb table to 2^16")
Fixes: 190cc82489 ("tcp: change source port randomizarion at connect() time")
Reported-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/netdev/CANn89iLAEYBaoYajy0Y9UmGFff5GPxDUoG-ErVB2jDdRNQ5Tug@mail.gmail.com/T/#t
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willy Tarreau <w@1wt.eu>
Tested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>
The v6_rcv_saddr and rcv_saddr are inside a union in the
'struct inet_bind2_bucket'. When searching a bucket by following the
bhash2 hashtable chain, eg. inet_bind2_bucket_match, it is only using
the sk->sk_family and there is no way to check if the inet_bind2_bucket
has a v6 or v4 address in the union. This leads to an uninit-value
KMSAN report in [0] and also potentially incorrect matches.
This patch fixes it by adding a family member to the inet_bind2_bucket
and then tests 'sk->sk_family != tb->family' before matching
the sk's address to the tb's address.
Cc: Joanne Koong <joannelkoong@gmail.com>
Fixes: 28044fc1d4 ("net: Add a bhash2 table hashed by port and address")
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Tested-by: Alexander Potapenko <glider@google.com>
Link: https://lore.kernel.org/r/20220927002544.3381205-1-kafai@fb.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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>
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>
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>
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>
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>
In our server, there may be no high order (>= 6) memory since we reserve
lots of HugeTLB pages when booting. Then the system panic. So use
alloc_large_system_hash() to allocate table_perturb.
Fixes: e926147618 ("tcp: dynamically allocate the perturb table used by source ports")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20220607070214.94443-1-songmuchun@bytedance.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
