This is a note to let you know that I've just added the patch titled
net: Introduce net.ipv4.tcp_migrate_req.
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-introduce-net.ipv4.tcp_migrate_req.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ae21150f40b0f78661a99973150ac17b5503fced
Author: Kuniyuki Iwashima <kuniyu@xxxxxxxxxxxx>
Date: Sat Jun 12 21:32:14 2021 +0900
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@xxxxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Reviewed-by: Benjamin Herrenschmidt <benh@xxxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Acked-by: Martin KaFai Lau <kafai@xxxxxx>
Link: https://lore.kernel.org/bpf/20210612123224.12525-2-kuniyu@xxxxxxxxxxxx
Stable-dep-of: 3a037f0f3c4b ("tcp: annotate data-races around icsk->icsk_syn_retries")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index df26cf4110ef5..252212998378e 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -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.
diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 4a4a5270ff6f2..9b0d8649ae5b8 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -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;
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 5aa8bde3e9c8e..59ba518a85b9c 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -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,
