[PATCH bpf-next 6/7] selftests: bpf: verify ca_name of struct mptcp_sock

Mat Martineau
2022-04-20T22:25:24Z

From: Geliang Tang <geliang.tang@suse.com>

This patch verifies another member of struct mptcp_sock, ca_name. Add a
new function get_msk_ca_name() to read the sysctl tcp_congestion_control
and verify it in verify_msk().

Acked-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
.../testing/selftests/bpf/bpf_mptcp_helpers.h | 1 +
tools/testing/selftests/bpf/bpf_tcp_helpers.h | 4 ++++
.../testing/selftests/bpf/prog_tests/mptcp.c | 24 +++++++++++++++++++
.../testing/selftests/bpf/progs/mptcp_sock.c | 4 ++++
4 files changed, 33 insertions(+)

diff --git a/tools/testing/selftests/bpf/bpf_mptcp_helpers.h b/tools/testing/selftests/bpf/bpf_mptcp_helpers.h
index 87e15810997d..463e4e061c96 100644
--- a/tools/testing/selftests/bpf/bpf_mptcp_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_mptcp_helpers.h
@@ -10,6 +10,7 @@ struct mptcp_sock {
struct inet_connection_sock sk;

__u32 token;
+ char ca_name[TCP_CA_NAME_MAX];
} __attribute__((preserve_access_index));

#endif
diff --git a/tools/testing/selftests/bpf/bpf_tcp_helpers.h b/tools/testing/selftests/bpf/bpf_tcp_helpers.h
index b1ede6f0b821..89750d732cfa 100644
--- a/tools/testing/selftests/bpf/bpf_tcp_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_tcp_helpers.h
@@ -16,6 +16,10 @@ BPF_PROG(name, args)
#define SOL_TCP 6
#endif

+#ifndef TCP_CA_NAME_MAX
+#define TCP_CA_NAME_MAX 16
+#endif
+
#define tcp_jiffies32 ((__u32)bpf_jiffies64())

struct sock_common {
diff --git a/tools/testing/selftests/bpf/prog_tests/mptcp.c b/tools/testing/selftests/bpf/prog_tests/mptcp.c
index c5d96ba81e04..4518aa6e661e 100644
--- a/tools/testing/selftests/bpf/prog_tests/mptcp.c
+++ b/tools/testing/selftests/bpf/prog_tests/mptcp.c
@@ -5,10 +5,15 @@
#include "cgroup_helpers.h"
#include "network_helpers.h"

+#ifndef TCP_CA_NAME_MAX
+#define TCP_CA_NAME_MAX 16
+#endif
+
struct mptcp_storage {
__u32 invoked;
__u32 is_mptcp;
__u32 token;
+ char ca_name[TCP_CA_NAME_MAX];
};

static char monitor_log_path[64];
@@ -79,11 +84,22 @@ static __u32 get_msk_token(void)
return token;
}

+void get_msk_ca_name(char ca_name[])
+{
+ FILE *stream = popen("sysctl -b net.ipv4.tcp_congestion_control", "r");
+
+ if (!fgets(ca_name, TCP_CA_NAME_MAX, stream))
+ log_err("Failed to read ca_name");
+
+ pclose(stream);
+}
+
static int verify_msk(int map_fd, int client_fd)
{
char *msg = "MPTCP subflow socket";
int err = 0, cfd = client_fd;
struct mptcp_storage val;
+ char ca_name[TCP_CA_NAME_MAX];
__u32 token;

token = get_msk_token();
@@ -92,6 +108,8 @@ static int verify_msk(int map_fd, int client_fd)
return -1;
}

+ get_msk_ca_name(ca_name);
+
if (CHECK_FAIL(bpf_map_lookup_elem(map_fd, &cfd, &val) < 0)) {
perror("Failed to read socket storage");
return -1;
@@ -115,6 +133,12 @@ static int verify_msk(int map_fd, int client_fd)
err++;
}

+ if (strncmp(val.ca_name, ca_name, TCP_CA_NAME_MAX)) {
+ log_err("Unexpected mptcp_sock.ca_name %s != %s",
+ val.ca_name, ca_name);
+ err++;
+ }
+
return err;
}

diff --git a/tools/testing/selftests/bpf/progs/mptcp_sock.c b/tools/testing/selftests/bpf/progs/mptcp_sock.c
index 56cc7c61131b..53bf67580010 100644
--- a/tools/testing/selftests/bpf/progs/mptcp_sock.c
+++ b/tools/testing/selftests/bpf/progs/mptcp_sock.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2020, Tessares SA. */

+#include <string.h>
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include "bpf_mptcp_helpers.h"
@@ -12,6 +13,7 @@ struct mptcp_storage {
__u32 invoked;
__u32 is_mptcp;
__u32 token;
+ char ca_name[TCP_CA_NAME_MAX];
};

struct {
@@ -48,6 +50,7 @@ int _sockops(struct bpf_sock_ops *ctx)
return 1;

storage->token = 0;
+ bzero(storage->ca_name, TCP_CA_NAME_MAX);
} else {
msk = bpf_skc_to_mptcp_sock(sk);
if (!msk)
@@ -59,6 +62,7 @@ int _sockops(struct bpf_sock_ops *ctx)
return 1;

storage->token = msk->token;
+ memcpy(storage->ca_name, msk->ca_name, TCP_CA_NAME_MAX);
}
storage->invoked++;
storage->is_mptcp = tcp_sk->is_mptcp;
--
2.36.0