| Message ID | 15a618b03f65177166adf2850d4159cd4b77dfb1.1691808484.git.geliang.tang@suse.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | bpf: Force to MPTCP | expand |
On 8/11/23 7:54 PM, Geliang Tang wrote: > +static int verify_mptcpify(int server_fd) > +{ > + socklen_t optlen; > + char cmd[256]; > + 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++; > + > + /* Output of nstat: > + * > + * #kernel > + * MPTcpExtMPCapableSYNACKRX 1 0.0 > + */ > + snprintf(cmd, sizeof(cmd), > + "ip netns exec %s nstat -asz %s | awk '%s' | grep -q '%s'", > + NS_TEST, "MPTcpExtMPCapableSYNACKRX", > + "NR==1 {next} {print $2}", "1"); Is the mp-capable something that the regular mptcp user want to learn from a fd also? Does it have a simpler way like to learn this, eg. getsockopt(fd, SOL_MPTCP, MPTCP_xxx), instead of parsing text output? > + if (!ASSERT_OK(system(cmd), "No MPTcpExtMPCapableSYNACKRX found!"))
On Mon, Aug 14, 2023 at 11:23:49PM -0700, Martin KaFai Lau wrote: > On 8/11/23 7:54 PM, Geliang Tang wrote: > > +static int verify_mptcpify(int server_fd) > > +{ > > + socklen_t optlen; > > + char cmd[256]; > > + 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++; > > + > > + /* Output of nstat: > > + * > > + * #kernel > > + * MPTcpExtMPCapableSYNACKRX 1 0.0 > > + */ > > + snprintf(cmd, sizeof(cmd), > > + "ip netns exec %s nstat -asz %s | awk '%s' | grep -q '%s'", > > + NS_TEST, "MPTcpExtMPCapableSYNACKRX", > > + "NR==1 {next} {print $2}", "1"); > > Is the mp-capable something that the regular mptcp user want to learn from a > fd also? Does it have a simpler way like to learn this, eg. getsockopt(fd, > SOL_MPTCP, MPTCP_xxx), instead of parsing text output? Thanks Martin. Yes, you're right. A better one is using getsockopt (MPTCP_INFO) to get the mptcpi_flags, then test the FALLBACK bit to make sure this MPTCP connection didn't fallback. This is, in other word, this MPTCP connection has been established correctly. Something like this: + optlen = sizeof(info); + if (!ASSERT_OK(getsockopt(fd, SOL_MPTCP, MPTCP_INFO, &info, &optlen), + "getsockopt(MPTCP_INFO)")) + return -1; + + if (!ASSERT_FALSE(info.mptcpi_flags & MPTCP_INFO_FLAG_FALLBACK, + "MPTCP fallback")) + err++; It's necessary to add this further check after the MPTCP protocol check using getsockopt(SOL_PROTOCOL). Since in some cases, the MPTCP protocol check is not enough. Say, if we change TCP protocol into MPTCP using "cgroup/sock_create", the hook of BPF_CGROUP_RUN_PROG_INET_SOCK in inet_create(), this place is too late to change the protocol. Although sk->sk_protocol is set to MPTCP correctly, and the MPTCP protocol check using getsockopt(SOL_PROTOCOL) will pass. This MPTCP connection will fallback to TCP connection. So this further check is needed. -Geliang > > > + if (!ASSERT_OK(system(cmd), "No MPTcpExtMPCapableSYNACKRX found!")) > >
On 8/15/23 3:08 AM, Geliang Tang wrote: > On Mon, Aug 14, 2023 at 11:23:49PM -0700, Martin KaFai Lau wrote: >> On 8/11/23 7:54 PM, Geliang Tang wrote: >>> +static int verify_mptcpify(int server_fd) >>> +{ >>> + socklen_t optlen; >>> + char cmd[256]; >>> + 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++; >>> + >>> + /* Output of nstat: >>> + * >>> + * #kernel >>> + * MPTcpExtMPCapableSYNACKRX 1 0.0 >>> + */ >>> + snprintf(cmd, sizeof(cmd), >>> + "ip netns exec %s nstat -asz %s | awk '%s' | grep -q '%s'", >>> + NS_TEST, "MPTcpExtMPCapableSYNACKRX", >>> + "NR==1 {next} {print $2}", "1"); >> >> Is the mp-capable something that the regular mptcp user want to learn from a >> fd also? Does it have a simpler way like to learn this, eg. getsockopt(fd, >> SOL_MPTCP, MPTCP_xxx), instead of parsing text output? > > Thanks Martin. Yes, you're right. A better one is using getsockopt > (MPTCP_INFO) to get the mptcpi_flags, then test the FALLBACK bit to make > sure this MPTCP connection didn't fallback. This is, in other word, this > MPTCP connection has been established correctly. Something like this: > > + optlen = sizeof(info); > + if (!ASSERT_OK(getsockopt(fd, SOL_MPTCP, MPTCP_INFO, &info, &optlen), > + "getsockopt(MPTCP_INFO)")) > + return -1; > + > + if (!ASSERT_FALSE(info.mptcpi_flags & MPTCP_INFO_FLAG_FALLBACK, > + "MPTCP fallback")) > + err++; > > It's necessary to add this further check after the MPTCP protocol check > using getsockopt(SOL_PROTOCOL). Since in some cases, the MPTCP protocol > check is not enough. Say, if we change TCP protocol into MPTCP using > "cgroup/sock_create", the hook of BPF_CGROUP_RUN_PROG_INET_SOCK in > inet_create(), this place is too late to change the protocol. Although > sk->sk_protocol is set to MPTCP correctly, and the MPTCP protocol check > using getsockopt(SOL_PROTOCOL) will pass. This MPTCP connection will > fallback to TCP connection. So this further check is needed. If I read it correctly, it sounds like the "ip netns... nstat.... awk...grep..." can be replaced with the getsockopt(MPTCP_INFO)? If that is the case, could you respin one more time to do getsockopt(MPTCP_INFO) instead? I would like the test to avoid parsing text output and have less dependency on external binary/library if possible (On top of 'ip', the above uses nstat, awk, grep...). This will make the bpf CI and other developers' environment tricky to maintain. eg. fwiw, although unrelated to the commands used above, my dev environment suddenly like to give this text output when I run "e"grep: "egrep: warning: egrep is obsolescent; using grep -E" >> >>> + if (!ASSERT_OK(system(cmd), "No MPTcpExtMPCapableSYNACKRX found!")) >> >>
diff --git a/tools/testing/selftests/bpf/prog_tests/mptcp.c b/tools/testing/selftests/bpf/prog_tests/mptcp.c index 3d3999067e27..a6bbc734a876 100644 --- a/tools/testing/selftests/bpf/prog_tests/mptcp.c +++ b/tools/testing/selftests/bpf/prog_tests/mptcp.c @@ -2,13 +2,19 @@ /* Copyright (c) 2020, Tessares SA. */ /* Copyright (c) 2022, SUSE. */ +#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 TCP_CA_NAME_MAX #define TCP_CA_NAME_MAX 16 #endif @@ -183,8 +189,104 @@ static void test_base(void) close(cgroup_fd); } +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) +{ + socklen_t optlen; + char cmd[256]; + 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++; + + /* Output of nstat: + * + * #kernel + * MPTcpExtMPCapableSYNACKRX 1 0.0 + */ + snprintf(cmd, sizeof(cmd), + "ip netns exec %s nstat -asz %s | awk '%s' | grep -q '%s'", + NS_TEST, "MPTcpExtMPCapableSYNACKRX", + "NR==1 {next} {print $2}", "1"); + if (!ASSERT_OK(system(cmd), "No MPTcpExtMPCapableSYNACKRX found!")) + 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); + + 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); +} + void test_mptcp(void) { if (test__start_subtest("base")) test_base(); + if (test__start_subtest("mptcpify")) + test_mptcpify(); } diff --git a/tools/testing/selftests/bpf/progs/mptcpify.c b/tools/testing/selftests/bpf/progs/mptcpify.c new file mode 100644 index 000000000000..53301ae8a8f7 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/mptcpify.c @@ -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; +}