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Merge branch 'bpf: Force to MPTCP'

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Geliang Tang says:

====================
As is described in the "How to use MPTCP?" section in MPTCP wiki [1]:

"Your app should create sockets with IPPROTO_MPTCP as the proto:
( socket(AF_INET, SOCK_STREAM, IPPROTO_MPTCP); ). Legacy apps can be
forced to create and use MPTCP sockets instead of TCP ones via the
mptcpize command bundled with the mptcpd daemon."

But the mptcpize (LD_PRELOAD technique) command has some limitations
[2]:

 - it doesn't work if the application is not using libc (e.g. GoLang
apps)
 - in some envs, it might not be easy to set env vars / change the way
apps are launched, e.g. on Android
 - mptcpize needs to be launched with all apps that want MPTCP: we could
have more control from BPF to enable MPTCP only for some apps or all the
ones of a netns or a cgroup, etc.
 - it is not in BPF, we cannot talk about it at netdev conf.

So this patchset attempts to use BPF to implement functions similer to
mptcpize.

The main idea is to add a hook in sys_socket() to change the protocol id
from IPPROTO_TCP (or 0) to IPPROTO_MPTCP.

[1]
https://github.com/multipath-tcp/mptcp_net-next/wiki
[2]
https://github.com/multipath-tcp/mptcp_net-next/issues/79

v14:
 - Use getsockopt(MPTCP_INFO) to verify mptcp protocol intead of using
nstat command.

v13:
 - drop "Use random netns name for mptcp" patch.

v12:
 - update diag_* log of update_socket_protocol.
 - add 'ip netns show' after 'ip netns del' to check if there is
a test did not clean up its netns.
 - return libbpf_get_error() instead of -EIO for the error from
open_and_load().
 - Use getsockopt(SOL_PROTOCOL) to verify mptcp protocol intead of
using 'ss -tOni'.

v11:
 - add comments about outputs of 'ss' and 'nstat'.
 - use "err = verify_mptcpify()" instead of using =+.

v10:
 - drop "#ifdef CONFIG_BPF_JIT".
 - include vmlinux.h and bpf_tracing_net.h to avoid defining some
macros.
 - drop unneeded checks for mptcp.

v9:
 - update comment for 'update_socket_protocol'.

v8:
 - drop the additional checks on the 'protocol' value after the
'update_socket_protocol()' call.

v7:
 - add __weak and __diag_* for update_socket_protocol.

v6:
 - add update_socket_protocol.

v5:
 - add bpf_mptcpify helper.

v4:
 - use lsm_cgroup/socket_create

v3:
 - patch 8: char cmd[128]; -> char cmd[256];

v2:
 - Fix build selftests errors reported by CI

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/79
====================

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
This commit is contained in:
Martin KaFai Lau 2023-08-16 10:22:17 -07:00
commit de40537364
4 changed files with 221 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
net/mptcp/bpf.c
View File

@ -19,3 +19,18 @@ struct mptcp_sock *bpf_mptcp_sock_from_subflow(struct sock *sk)
return NULL;
}
BTF_SET8_START(bpf_mptcp_fmodret_ids)
BTF_ID_FLAGS(func, update_socket_protocol)
BTF_SET8_END(bpf_mptcp_fmodret_ids)
static const struct btf_kfunc_id_set bpf_mptcp_fmodret_set = {
.owner = THIS_MODULE,
.set = &bpf_mptcp_fmodret_ids,
};
static int __init bpf_mptcp_kfunc_init(void)
{
return register_btf_fmodret_id_set(&bpf_mptcp_fmodret_set);
}
late_initcall(bpf_mptcp_kfunc_init);

26
net/socket.c
View File

@ -1657,12 +1657,36 @@ struct file *__sys_socket_file(int family, int type, int protocol)
return sock_alloc_file(sock, flags, NULL);
}
/* A hook for bpf progs to attach to and update socket protocol.
*
* A static noinline declaration here could cause the compiler to
* optimize away the function. A global noinline declaration will
* keep the definition, but may optimize away the callsite.
* Therefore, __weak is needed to ensure that the call is still
* emitted, by telling the compiler that we don't know what the
* function might eventually be.
*
* __diag_* below are needed to dismiss the missing prototype warning.
*/
__diag_push();
__diag_ignore_all("-Wmissing-prototypes",
"A fmod_ret entry point for BPF programs");
__weak noinline int update_socket_protocol(int family, int type, int protocol)
{
return protocol;
}
__diag_pop();
int __sys_socket(int family, int type, int protocol)
{
struct socket *sock;
int flags;
sock = __sys_socket_create(family, type, protocol);
sock = __sys_socket_create(family, type,
update_socket_protocol(family, type, protocol));
if (IS_ERR(sock))
return PTR_ERR(sock);

180
tools/testing/selftests/bpf/prog_tests/mptcp.c
View File

@ -2,17 +2,59 @@
/* Copyright (c) 2020, Tessares SA. */
/* Copyright (c) 2022, SUSE. */
#include <linux/const.h>
#include <netinet/in.h>
#include <test_progs.h>
#include "cgroup_helpers.h"
#include "network_helpers.h"
#include "mptcp_sock.skel.h"
#include "mptcpify.skel.h"
#define NS_TEST "mptcp_ns"
#ifndef IPPROTO_MPTCP
#define IPPROTO_MPTCP 262
#endif
#ifndef SOL_MPTCP
#define SOL_MPTCP 284
#endif
#ifndef MPTCP_INFO
#define MPTCP_INFO 1
#endif
#ifndef MPTCP_INFO_FLAG_FALLBACK
#define MPTCP_INFO_FLAG_FALLBACK _BITUL(0)
#endif
#ifndef MPTCP_INFO_FLAG_REMOTE_KEY_RECEIVED
#define MPTCP_INFO_FLAG_REMOTE_KEY_RECEIVED _BITUL(1)
#endif
#ifndef TCP_CA_NAME_MAX
#define TCP_CA_NAME_MAX 16
#endif
struct __mptcp_info {
__u8 mptcpi_subflows;
__u8 mptcpi_add_addr_signal;
__u8 mptcpi_add_addr_accepted;
__u8 mptcpi_subflows_max;
__u8 mptcpi_add_addr_signal_max;
__u8 mptcpi_add_addr_accepted_max;
__u32 mptcpi_flags;
__u32 mptcpi_token;
__u64 mptcpi_write_seq;
__u64 mptcpi_snd_una;
__u64 mptcpi_rcv_nxt;
__u8 mptcpi_local_addr_used;
__u8 mptcpi_local_addr_max;
__u8 mptcpi_csum_enabled;
__u32 mptcpi_retransmits;
__u64 mptcpi_bytes_retrans;
__u64 mptcpi_bytes_sent;
__u64 mptcpi_bytes_received;
__u64 mptcpi_bytes_acked;
};
struct mptcp_storage {
__u32 invoked;
__u32 is_mptcp;
@ -22,6 +64,24 @@ struct mptcp_storage {
char ca_name[TCP_CA_NAME_MAX];
};
static struct nstoken *create_netns(void)
{
SYS(fail, "ip netns add %s", NS_TEST);
SYS(fail, "ip -net %s link set dev lo up", NS_TEST);
return open_netns(NS_TEST);
fail:
return NULL;
}
static void cleanup_netns(struct nstoken *nstoken)
{
if (nstoken)
close_netns(nstoken);
SYS_NOFAIL("ip netns del %s &> /dev/null", NS_TEST);
}
static int verify_tsk(int map_fd, int client_fd)
{
int err, cfd = client_fd;
@ -100,24 +160,14 @@ static int run_test(int cgroup_fd, int server_fd, bool is_mptcp)
sock_skel = mptcp_sock__open_and_load();
if (!ASSERT_OK_PTR(sock_skel, "skel_open_load"))
return -EIO;
return libbpf_get_error(sock_skel);
err = mptcp_sock__attach(sock_skel);
if (!ASSERT_OK(err, "skel_attach"))
goto out;
prog_fd = bpf_program__fd(sock_skel->progs._sockops);
if (!ASSERT_GE(prog_fd, 0, "bpf_program__fd")) {
err = -EIO;
goto out;
}
map_fd = bpf_map__fd(sock_skel->maps.socket_storage_map);
if (!ASSERT_GE(map_fd, 0, "bpf_map__fd")) {
err = -EIO;
goto out;
}
err = bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_SOCK_OPS, 0);
if (!ASSERT_OK(err, "bpf_prog_attach"))
goto out;
@ -147,11 +197,8 @@ static void test_base(void)
if (!ASSERT_GE(cgroup_fd, 0, "test__join_cgroup"))
return;
SYS(fail, "ip netns add %s", NS_TEST);
SYS(fail, "ip -net %s link set dev lo up", NS_TEST);
nstoken = open_netns(NS_TEST);
if (!ASSERT_OK_PTR(nstoken, "open_netns"))
nstoken = create_netns();
if (!ASSERT_OK_PTR(nstoken, "create_netns"))
goto fail;
/* without MPTCP */
@ -174,11 +221,104 @@ with_mptcp:
close(server_fd);
fail:
if (nstoken)
close_netns(nstoken);
cleanup_netns(nstoken);
close(cgroup_fd);
}
SYS_NOFAIL("ip netns del " NS_TEST " &> /dev/null");
static void send_byte(int fd)
{
char b = 0x55;
ASSERT_EQ(write(fd, &b, sizeof(b)), 1, "send single byte");
}
static int verify_mptcpify(int server_fd, int client_fd)
{
struct __mptcp_info info;
socklen_t optlen;
int protocol;
int err = 0;
optlen = sizeof(protocol);
if (!ASSERT_OK(getsockopt(server_fd, SOL_SOCKET, SO_PROTOCOL, &protocol, &optlen),
"getsockopt(SOL_PROTOCOL)"))
return -1;
if (!ASSERT_EQ(protocol, IPPROTO_MPTCP, "protocol isn't MPTCP"))
err++;
optlen = sizeof(info);
if (!ASSERT_OK(getsockopt(client_fd, SOL_MPTCP, MPTCP_INFO, &info, &optlen),
"getsockopt(MPTCP_INFO)"))
return -1;
if (!ASSERT_GE(info.mptcpi_flags, 0, "unexpected mptcpi_flags"))
err++;
if (!ASSERT_FALSE(info.mptcpi_flags & MPTCP_INFO_FLAG_FALLBACK,
"MPTCP fallback"))
err++;
if (!ASSERT_TRUE(info.mptcpi_flags & MPTCP_INFO_FLAG_REMOTE_KEY_RECEIVED,
"no remote key received"))
err++;
return err;
}
static int run_mptcpify(int cgroup_fd)
{
int server_fd, client_fd, err = 0;
struct mptcpify *mptcpify_skel;
mptcpify_skel = mptcpify__open_and_load();
if (!ASSERT_OK_PTR(mptcpify_skel, "skel_open_load"))
return libbpf_get_error(mptcpify_skel);
err = mptcpify__attach(mptcpify_skel);
if (!ASSERT_OK(err, "skel_attach"))
goto out;
/* without MPTCP */
server_fd = start_server(AF_INET, SOCK_STREAM, NULL, 0, 0);
if (!ASSERT_GE(server_fd, 0, "start_server")) {
err = -EIO;
goto out;
}
client_fd = connect_to_fd(server_fd, 0);
if (!ASSERT_GE(client_fd, 0, "connect to fd")) {
err = -EIO;
goto close_server;
}
send_byte(client_fd);
err = verify_mptcpify(server_fd, client_fd);
close(client_fd);
close_server:
close(server_fd);
out:
mptcpify__destroy(mptcpify_skel);
return err;
}
static void test_mptcpify(void)
{
struct nstoken *nstoken = NULL;
int cgroup_fd;
cgroup_fd = test__join_cgroup("/mptcpify");
if (!ASSERT_GE(cgroup_fd, 0, "test__join_cgroup"))
return;
nstoken = create_netns();
if (!ASSERT_OK_PTR(nstoken, "create_netns"))
goto fail;
ASSERT_OK(run_mptcpify(cgroup_fd), "run_mptcpify");
fail:
cleanup_netns(nstoken);
close(cgroup_fd);
}
@ -186,4 +326,6 @@ void test_mptcp(void)
{
if (test__start_subtest("base"))
test_base();
if (test__start_subtest("mptcpify"))
test_mptcpify();
}

20
tools/testing/selftests/bpf/progs/mptcpify.c Normal file
View File

@ -0,0 +1,20 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2023, SUSE. */
#include "vmlinux.h"
#include <bpf/bpf_tracing.h>
#include "bpf_tracing_net.h"
char _license[] SEC("license") = "GPL";
SEC("fmod_ret/update_socket_protocol")
int BPF_PROG(mptcpify, int family, int type, int protocol)
{
if ((family == AF_INET || family == AF_INET6) &&
type == SOCK_STREAM &&
(!protocol || protocol == IPPROTO_TCP)) {
return IPPROTO_MPTCP;
}
return protocol;
}