net: Introduce net.ipv4.tcp_migrate_req.

[ Upstream commit f9ac779f881c2ec3d1cdcd7fa9d4f9442bf60e80 ]

This commit adds a new sysctl option: net.ipv4.tcp_migrate_req. If this
option is enabled or eBPF program is attached, we will be able to migrate
child sockets from a listener to another in the same reuseport group after
close() or shutdown() syscalls.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Benjamin Herrenschmidt <benh@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210612123224.12525-2-kuniyu@amazon.co.jp
Stable-dep-of: 3a037f0f3c4b ("tcp: annotate data-races around icsk->icsk_syn_retries")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Kuniyuki Iwashima 2021-06-12 21:32:14 +09:00 committed by Greg Kroah-Hartman
parent a5c30a5187
commit cf6c06ac74
3 changed files with 35 additions and 0 deletions

View File

@ -713,6 +713,31 @@ tcp_syncookies - INTEGER
network connections you can set this knob to 2 to enable
unconditionally generation of syncookies.
tcp_migrate_req - BOOLEAN
The incoming connection is tied to a specific listening socket when
the initial SYN packet is received during the three-way handshake.
When a listener is closed, in-flight request sockets during the
handshake and established sockets in the accept queue are aborted.
If the listener has SO_REUSEPORT enabled, other listeners on the
same port should have been able to accept such connections. This
option makes it possible to migrate such child sockets to another
listener after close() or shutdown().
The BPF_SK_REUSEPORT_SELECT_OR_MIGRATE type of eBPF program should
usually be used to define the policy to pick an alive listener.
Otherwise, the kernel will randomly pick an alive listener only if
this option is enabled.
Note that migration between listeners with different settings may
crash applications. Let's say migration happens from listener A to
B, and only B has TCP_SAVE_SYN enabled. B cannot read SYN data from
the requests migrated from A. To avoid such a situation, cancel
migration by returning SK_DROP in the type of eBPF program, or
disable this option.
Default: 0
tcp_fastopen - INTEGER
Enable TCP Fast Open (RFC7413) to send and accept data in the opening
SYN packet.

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@ -131,6 +131,7 @@ struct netns_ipv4 {
u8 sysctl_tcp_syn_retries;
u8 sysctl_tcp_synack_retries;
u8 sysctl_tcp_syncookies;
u8 sysctl_tcp_migrate_req;
int sysctl_tcp_reordering;
u8 sysctl_tcp_retries1;
u8 sysctl_tcp_retries2;

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@ -878,6 +878,15 @@ static struct ctl_table ipv4_net_table[] = {
.proc_handler = proc_dou8vec_minmax,
},
#endif
{
.procname = "tcp_migrate_req",
.data = &init_net.ipv4.sysctl_tcp_migrate_req,
.maxlen = sizeof(u8),
.mode = 0644,
.proc_handler = proc_dou8vec_minmax,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE
},
{
.procname = "tcp_reordering",
.data = &init_net.ipv4.sysctl_tcp_reordering,