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bpf:selftests: add MPTCP test base
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This patch adds a base for MPTCP specific tests.

It is currently limited to the is_mptcp field in case of plain TCP
connection because there is no easy way to get the subflow sk from a msk
in userspace. This implies that we cannot lookup the sk_storage attached
to the subflow sk in the sockops program.

Acked-by: Matthieu Baerts <[email protected]>
Signed-off-by: Nicolas Rybowski <[email protected]>
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nrybowski authored and jenkins-tessares committed Feb 7, 2021
1 parent 1e8a1ee commit 6512eb1
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Showing 5 changed files with 203 additions and 5 deletions.
1 change: 1 addition & 0 deletions tools/testing/selftests/bpf/config
Original file line number Diff line number Diff line change
Expand Up @@ -44,3 +44,4 @@ CONFIG_SECURITYFS=y
CONFIG_IMA_WRITE_POLICY=y
CONFIG_IMA_READ_POLICY=y
CONFIG_BLK_DEV_LOOP=y
CONFIG_MPTCP=y
37 changes: 32 additions & 5 deletions tools/testing/selftests/bpf/network_helpers.c
Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,10 @@
#include "bpf_util.h"
#include "network_helpers.h"

#ifndef IPPROTO_MPTCP
#define IPPROTO_MPTCP 262
#endif

#define clean_errno() (errno == 0 ? "None" : strerror(errno))
#define log_err(MSG, ...) ({ \
int __save = errno; \
Expand Down Expand Up @@ -66,8 +70,8 @@ static int settimeo(int fd, int timeout_ms)

#define save_errno_close(fd) ({ int __save = errno; close(fd); errno = __save; })

int start_server(int family, int type, const char *addr_str, __u16 port,
int timeout_ms)
static int start_server_proto(int family, int type, int protocol,
const char *addr_str, __u16 port, int timeout_ms)
{
struct sockaddr_storage addr = {};
socklen_t len;
Expand All @@ -76,7 +80,7 @@ int start_server(int family, int type, const char *addr_str, __u16 port,
if (make_sockaddr(family, addr_str, port, &addr, &len))
return -1;

fd = socket(family, type, 0);
fd = socket(family, type, protocol);
if (fd < 0) {
log_err("Failed to create server socket");
return -1;
Expand Down Expand Up @@ -104,6 +108,19 @@ int start_server(int family, int type, const char *addr_str, __u16 port,
return -1;
}

int start_server(int family, int type, const char *addr_str, __u16 port,
int timeout_ms)
{
return start_server_proto(family, type, 0, addr_str, port, timeout_ms);
}

int start_mptcp_server(int family, const char *addr_str, __u16 port,
int timeout_ms)
{
return start_server_proto(family, SOCK_STREAM, IPPROTO_MPTCP, addr_str,
port, timeout_ms);
}

int fastopen_connect(int server_fd, const char *data, unsigned int data_len,
int timeout_ms)
{
Expand Down Expand Up @@ -153,7 +170,7 @@ static int connect_fd_to_addr(int fd,
return 0;
}

int connect_to_fd(int server_fd, int timeout_ms)
static int connect_to_fd_proto(int server_fd, int protocol, int timeout_ms)
{
struct sockaddr_storage addr;
struct sockaddr_in *addr_in;
Expand All @@ -173,7 +190,7 @@ int connect_to_fd(int server_fd, int timeout_ms)
}

addr_in = (struct sockaddr_in *)&addr;
fd = socket(addr_in->sin_family, type, 0);
fd = socket(addr_in->sin_family, type, protocol);
if (fd < 0) {
log_err("Failed to create client socket");
return -1;
Expand All @@ -192,6 +209,16 @@ int connect_to_fd(int server_fd, int timeout_ms)
return -1;
}

int connect_to_fd(int server_fd, int timeout_ms)
{
return connect_to_fd_proto(server_fd, 0, timeout_ms);
}

int connect_to_mptcp_fd(int server_fd, int timeout_ms)
{
return connect_to_fd_proto(server_fd, IPPROTO_MPTCP, timeout_ms);
}

int connect_fd_to_fd(int client_fd, int server_fd, int timeout_ms)
{
struct sockaddr_storage addr;
Expand Down
3 changes: 3 additions & 0 deletions tools/testing/selftests/bpf/network_helpers.h
Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,10 @@ extern struct ipv6_packet pkt_v6;

int start_server(int family, int type, const char *addr, __u16 port,
int timeout_ms);
int start_mptcp_server(int family, const char *addr, __u16 port,
int timeout_ms);
int connect_to_fd(int server_fd, int timeout_ms);
int connect_to_mptcp_fd(int server_fd, int timeout_ms);
int connect_fd_to_fd(int client_fd, int server_fd, int timeout_ms);
int fastopen_connect(int server_fd, const char *data, unsigned int data_len,
int timeout_ms);
Expand Down
119 changes: 119 additions & 0 deletions tools/testing/selftests/bpf/prog_tests/mptcp.c
Original file line number Diff line number Diff line change
@@ -0,0 +1,119 @@
// SPDX-License-Identifier: GPL-2.0
#include <test_progs.h>
#include "cgroup_helpers.h"
#include "network_helpers.h"

struct mptcp_storage {
__u32 invoked;
__u32 is_mptcp;
};

static int verify_sk(int map_fd, int client_fd, const char *msg, __u32 is_mptcp)
{
int err = 0, cfd = client_fd;
struct mptcp_storage val;

/* Currently there is no easy way to get back the subflow sk from the MPTCP
* sk, thus we cannot access here the sk_storage associated to the subflow
* sk. Also, there is no sk_storage associated with the MPTCP sk since it
* does not trigger sockops events.
* We silently pass this situation at the moment.
*/
if (is_mptcp == 1)
return 0;

if (CHECK_FAIL(bpf_map_lookup_elem(map_fd, &cfd, &val) < 0)) {
perror("Failed to read socket storage");
return -1;
}

if (val.invoked != 1) {
log_err("%s: unexpected invoked count %d != %d",
msg, val.invoked, 1);
err++;
}

if (val.is_mptcp != is_mptcp) {
log_err("%s: unexpected bpf_tcp_sock.is_mptcp %d != %d",
msg, val.is_mptcp, is_mptcp);
err++;
}

return err;
}

static int run_test(int cgroup_fd, int server_fd, bool is_mptcp)
{
int client_fd, prog_fd, map_fd, err;
struct bpf_object *obj;
struct bpf_map *map;

struct bpf_prog_load_attr attr = {
.prog_type = BPF_PROG_TYPE_SOCK_OPS,
.file = "./mptcp.o",
.expected_attach_type = BPF_CGROUP_SOCK_OPS,
};

err = bpf_prog_load_xattr(&attr, &obj, &prog_fd);
if (err) {
log_err("Failed to load BPF object");
return -1;
}

map = bpf_map__next(NULL, obj);
map_fd = bpf_map__fd(map);

err = bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_SOCK_OPS, 0);
if (err) {
log_err("Failed to attach BPF program");
goto close_bpf_object;
}

client_fd = is_mptcp ? connect_to_mptcp_fd(server_fd, 0) :
connect_to_fd(server_fd, 0);
if (client_fd < 0) {
err = -1;
goto close_client_fd;
}

err += is_mptcp ? verify_sk(map_fd, client_fd, "MPTCP subflow socket", 1) :
verify_sk(map_fd, client_fd, "plain TCP socket", 0);

close_client_fd:
close(client_fd);

close_bpf_object:
bpf_object__close(obj);
return err;
}

void test_mptcp(void)
{
int server_fd, cgroup_fd;

cgroup_fd = test__join_cgroup("/mptcp");
if (CHECK_FAIL(cgroup_fd < 0))
return;

/* without MPTCP */
server_fd = start_server(AF_INET, SOCK_STREAM, NULL, 0, 0);
if (CHECK_FAIL(server_fd < 0))
goto with_mptcp;

CHECK_FAIL(run_test(cgroup_fd, server_fd, false));

close(server_fd);

with_mptcp:
/* with MPTCP */
server_fd = start_mptcp_server(AF_INET, NULL, 0, 0);
if (CHECK_FAIL(server_fd < 0))
goto close_cgroup_fd;

CHECK_FAIL(run_test(cgroup_fd, server_fd, true));

close(server_fd);

close_cgroup_fd:
close(cgroup_fd);
}
48 changes: 48 additions & 0 deletions tools/testing/selftests/bpf/progs/mptcp.c
Original file line number Diff line number Diff line change
@@ -0,0 +1,48 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>

char _license[] SEC("license") = "GPL";
__u32 _version SEC("version") = 1;

struct mptcp_storage {
__u32 invoked;
__u32 is_mptcp;
};

struct {
__uint(type, BPF_MAP_TYPE_SK_STORAGE);
__uint(map_flags, BPF_F_NO_PREALLOC);
__type(key, int);
__type(value, struct mptcp_storage);
} socket_storage_map SEC(".maps");

SEC("sockops")
int _sockops(struct bpf_sock_ops *ctx)
{
struct mptcp_storage *storage;
struct bpf_tcp_sock *tcp_sk;
int op = (int)ctx->op;
struct bpf_sock *sk;

sk = ctx->sk;
if (!sk)
return 1;

storage = bpf_sk_storage_get(&socket_storage_map, sk, 0,
BPF_SK_STORAGE_GET_F_CREATE);
if (!storage)
return 1;

if (op != BPF_SOCK_OPS_TCP_CONNECT_CB)
return 1;

tcp_sk = bpf_tcp_sock(sk);
if (!tcp_sk)
return 1;

storage->invoked++;
storage->is_mptcp = tcp_sk->is_mptcp;

return 1;
}

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