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Kuniyuki Iwashima d5e4ddaeb6 bpf: Support socket migration by eBPF.
This patch introduces a new bpf_attach_type for BPF_PROG_TYPE_SK_REUSEPORT
to check if the attached eBPF program is capable of migrating sockets. When
the eBPF program is attached, we run it for socket migration if the
expected_attach_type is BPF_SK_REUSEPORT_SELECT_OR_MIGRATE or
net.ipv4.tcp_migrate_req is enabled.

Currently, the expected_attach_type is not enforced for the
BPF_PROG_TYPE_SK_REUSEPORT type of program. Thus, this commit follows the
earlier idea in the commit aac3fc320d ("bpf: Post-hooks for sys_bind") to
fix up the zero expected_attach_type in bpf_prog_load_fixup_attach_type().

Moreover, this patch adds a new field (migrating_sk) to sk_reuseport_md to
select a new listener based on the child socket. migrating_sk varies
depending on if it is migrating a request in the accept queue or during
3WHS.

  - accept_queue : sock (ESTABLISHED/SYN_RECV)
  - 3WHS         : request_sock (NEW_SYN_RECV)

In the eBPF program, we can select a new listener by
BPF_FUNC_sk_select_reuseport(). Also, we can cancel migration by returning
SK_DROP. This feature is useful when listeners have different settings at
the socket API level or when we want to free resources as soon as possible.

  - SK_PASS with selected_sk, select it as a new listener
  - SK_PASS with selected_sk NULL, fallbacks to the random selection
  - SK_DROP, cancel the migration.

There is a noteworthy point. We select a listening socket in three places,
but we do not have struct skb at closing a listener or retransmitting a
SYN+ACK. On the other hand, some helper functions do not expect skb is NULL
(e.g. skb_header_pointer() in BPF_FUNC_skb_load_bytes(), skb_tail_pointer()
in BPF_FUNC_skb_load_bytes_relative()). So we allocate an empty skb
temporarily before running the eBPF program.

Suggested-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/netdev/20201123003828.xjpjdtk4ygl6tg6h@kafai-mbp.dhcp.thefacebook.com/
Link: https://lore.kernel.org/netdev/20201203042402.6cskdlit5f3mw4ru@kafai-mbp.dhcp.thefacebook.com/
Link: https://lore.kernel.org/netdev/20201209030903.hhow5r53l6fmozjn@kafai-mbp.dhcp.thefacebook.com/
Link: https://lore.kernel.org/bpf/20210612123224.12525-10-kuniyu@amazon.co.jp
2021-06-15 18:01:06 +02:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-05-19 12:58:29 -07:00
block block-5.13-2021-05-07 2021-05-07 11:35:12 -07:00
certs Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
crypto for-5.13/drivers-2021-04-27 2021-04-28 14:39:37 -07:00
Documentation net: Introduce net.ipv4.tcp_migrate_req. 2021-06-15 18:01:05 +02:00
drivers ethernet: ucc_geth: Use kmemdup() rather than kmalloc+memcpy 2021-05-23 18:51:42 -07:00
fs Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
include bpf: Support socket migration by eBPF. 2021-06-15 18:01:06 +02:00
init Merge branch 'akpm' (patches from Andrew) 2021-05-07 00:34:51 -07:00
ipc ipc/sem.c: spelling fix 2021-05-07 00:26:34 -07:00
kernel bpf: Support socket migration by eBPF. 2021-06-15 18:01:06 +02:00
lib Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm mm: fix typos in comments 2021-05-07 00:26:35 -07:00
net bpf: Support socket migration by eBPF. 2021-06-15 18:01:06 +02:00
samples sample/bpf: Add xdp_redirect_map_multi for redirect_map broadcast test 2021-05-26 09:46:16 +02:00
scripts Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
security Simple code cleanup 2021-05-05 12:08:06 -07:00
sound sound fixes for 5.13-rc1 2021-05-07 11:40:18 -07:00
tools bpf: Support socket migration by eBPF. 2021-06-15 18:01:06 +02:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: Boost vCPU candidate in user mode which is delivering interrupt 2021-04-21 12:20:03 -04:00
.clang-format cxl for 5.12 2021-02-24 09:38:36 -08:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap It's been a relatively busy cycle in docsland, though more than usually 2021-04-26 13:22:43 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: move Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS net: phy: add driver for Motorcomm yt8511 phy 2021-05-21 13:19:11 -07:00
Makefile Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.