diff options
| author | Kuniyuki Iwashima <kuniyu@amazon.co.jp> | 2021-06-12 21:32:14 +0900 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2021-06-15 18:01:05 +0200 |
| commit | f9ac779f881c2ec3d1cdcd7fa9d4f9442bf60e80 (patch) | |
| tree | 1350ccbd2a33d8643e102339f265c5ec8a9931c8 /Documentation/networking/ip-sysctl.rst | |
| parent | bbf29d3a2e49e482d5267311798aec42f00e88f3 (diff) | |
| download | lwn-f9ac779f881c2ec3d1cdcd7fa9d4f9442bf60e80.tar.gz lwn-f9ac779f881c2ec3d1cdcd7fa9d4f9442bf60e80.zip | |
net: Introduce net.ipv4.tcp_migrate_req.
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
Diffstat (limited to 'Documentation/networking/ip-sysctl.rst')
| -rw-r--r-- | Documentation/networking/ip-sysctl.rst | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index a5c250044500..b0436d3a4f11 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -761,6 +761,31 @@ 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. |