[mptcp-next,v4,5/5] selftests/bpf: Add mptcp_userspace_pm_addr bpf_iter subtest

Commit Message

Geliang Tang Jan. 8, 2025, 8:38 a.m. UTC

From: Geliang Tang <[e-mail]>

This patch adds a test program for the newly added mptcp_userspace_pm_addr
bpf_iter in SEC "cgroup/getsockopt". This test iterates over all address
entries on the local address list of userspace PM and check whether each
one is an IPv4mapped address.

Export mptcp_userspace_pm_addr helpers _new/_next/_destroy into
bpf_experimental.h. Use bpf_mptcp_sock_acquire() to acquire the msk, then
lock the msk pm lock and use bpf_for_each(mptcp_userspace_pm_addr) to walk
the local address list of this msk. Invoke bpf_ipv4_is_private_10() in the
loop to check whether the address is a "10.*" one. Then Add the address ID
of each entry to local veriable local_ids.

Out of the loop, unlock the msk pm lock and use bpf_mptcp_sock_release() to
release the msk. Finally, assign local_ids to global variable ids so that
the application can obtain this value.

Also enable CONFIG_MPTCP_IPV6 in bpf config.

Add a subtest named test_iters_address to load and verify the newly added
mptcp_userspace_pm_addr type bpf_iter example in test_mptcp.

Since mptcp_userspace_pm_addr bpf_iter iterates over all address entries
on the local address list of userspace PM. A set of userspace PM helpers
are added.

Set pm_type and start "pm_nl_ctl events" command to save pm events into
the log file /tmp/bpf_userspace_pm_events in userspace_pm_init(). Kill
"pm_nl_ctl" command and remove the log file in userspace_pm_cleanup().
Parse the log file in userspace_pm_add_subflow() to get the token, sport
and dport values, then use "pm_nl_ctl csf" command to create a subflow.

Use the helper userspace_pm_add_subflow() to add 3 new subflow endpoints.
Send a byte of message to start the mptcp connection, and receive the
message.

getsockopt() is invoked to trigger the "cgroup/getsockopt" test program.
Check if skel->bss->ids equals 60 to verify whether the program loops
three times as expected.

Signed-off-by: Geliang Tang <[e-mail]>
---
 .../testing/selftests/bpf/bpf_experimental.h  |   8 +
 .../testing/selftests/bpf/prog_tests/mptcp.c  | 214 ++++++++++++++++++
 tools/testing/selftests/bpf/progs/mptcp_bpf.h |   5 +
 .../selftests/bpf/progs/mptcp_bpf_iters.c     |  38 ++++
 4 files changed, 265 insertions(+)

Comments

Geliang Tang Jan. 16, 2025, 3:08 a.m. UTC | #1

On Wed, 2025-01-08 at 16:38 +0800, Geliang Tang wrote:
> From: Geliang Tang <[e-mail]>
> 
> This patch adds a test program for the newly added
> mptcp_userspace_pm_addr
> bpf_iter in SEC "cgroup/getsockopt". This test iterates over all
> address
> entries on the local address list of userspace PM and check whether
> each
> one is an IPv4mapped address.
> 
> Export mptcp_userspace_pm_addr helpers _new/_next/_destroy into
> bpf_experimental.h. Use bpf_mptcp_sock_acquire() to acquire the msk,
> then
> lock the msk pm lock and use bpf_for_each(mptcp_userspace_pm_addr) to
> walk
> the local address list of this msk. Invoke bpf_ipv4_is_private_10()
> in the
> loop to check whether the address is a "10.*" one. Then Add the
> address ID
> of each entry to local veriable local_ids.
> 
> Out of the loop, unlock the msk pm lock and use
> bpf_mptcp_sock_release() to
> release the msk. Finally, assign local_ids to global variable ids so
> that
> the application can obtain this value.
> 
> Also enable CONFIG_MPTCP_IPV6 in bpf config.

This line should be dropped.

Will update it in the next version.

Thanks,
-Geliang

> 
> Add a subtest named test_iters_address to load and verify the newly
> added
> mptcp_userspace_pm_addr type bpf_iter example in test_mptcp.
> 
> Since mptcp_userspace_pm_addr bpf_iter iterates over all address
> entries
> on the local address list of userspace PM. A set of userspace PM
> helpers
> are added.
> 
> Set pm_type and start "pm_nl_ctl events" command to save pm events
> into
> the log file /tmp/bpf_userspace_pm_events in userspace_pm_init().
> Kill
> "pm_nl_ctl" command and remove the log file in
> userspace_pm_cleanup().
> Parse the log file in userspace_pm_add_subflow() to get the token,
> sport
> and dport values, then use "pm_nl_ctl csf" command to create a
> subflow.
> 
> Use the helper userspace_pm_add_subflow() to add 3 new subflow
> endpoints.
> Send a byte of message to start the mptcp connection, and receive the
> message.
> 
> getsockopt() is invoked to trigger the "cgroup/getsockopt" test
> program.
> Check if skel->bss->ids equals 60 to verify whether the program loops
> three times as expected.
> 
> Signed-off-by: Geliang Tang <[e-mail]>
> ---
>  .../testing/selftests/bpf/bpf_experimental.h  |   8 +
>  .../testing/selftests/bpf/prog_tests/mptcp.c  | 214
> ++++++++++++++++++
>  tools/testing/selftests/bpf/progs/mptcp_bpf.h |   5 +
>  .../selftests/bpf/progs/mptcp_bpf_iters.c     |  38 ++++
>  4 files changed, 265 insertions(+)
> 
> diff --git a/tools/testing/selftests/bpf/bpf_experimental.h
> b/tools/testing/selftests/bpf/bpf_experimental.h
> index 2ab3f0063c0f..01201917a446 100644
> --- a/tools/testing/selftests/bpf/bpf_experimental.h
> +++ b/tools/testing/selftests/bpf/bpf_experimental.h
> @@ -583,6 +583,14 @@ bpf_iter_mptcp_subflow_next(struct
> bpf_iter_mptcp_subflow *it) __weak __ksym;
>  extern void
>  bpf_iter_mptcp_subflow_destroy(struct bpf_iter_mptcp_subflow *it)
> __weak __ksym;
>  
> +struct bpf_iter_mptcp_userspace_pm_addr;
> +extern int bpf_iter_mptcp_userspace_pm_addr_new(struct
> bpf_iter_mptcp_userspace_pm_addr *it,
> +						struct mptcp_sock
> *msk) __weak __ksym;
> +extern struct mptcp_pm_addr_entry *
> +bpf_iter_mptcp_userspace_pm_addr_next(struct
> bpf_iter_mptcp_userspace_pm_addr *it) __weak __ksym;
> +extern void
> +bpf_iter_mptcp_userspace_pm_addr_destroy(struct
> bpf_iter_mptcp_userspace_pm_addr *it) __weak __ksym;
> +
>  extern int bpf_wq_init(struct bpf_wq *wq, void *p__map, unsigned int
> flags) __weak __ksym;
>  extern int bpf_wq_start(struct bpf_wq *wq, unsigned int flags)
> __weak __ksym;
>  extern int bpf_wq_set_callback_impl(struct bpf_wq *wq,
> diff --git a/tools/testing/selftests/bpf/prog_tests/mptcp.c
> b/tools/testing/selftests/bpf/prog_tests/mptcp.c
> index 5cab0aa8fb27..d50dc332f545 100644
> --- a/tools/testing/selftests/bpf/prog_tests/mptcp.c
> +++ b/tools/testing/selftests/bpf/prog_tests/mptcp.c
> @@ -29,6 +29,7 @@
>  #define ADDR6_4	"dead:beef:4::1"
>  #define PORT_1	10001
>  #define PM_CTL		"./mptcp_pm_nl_ctl"
> +#define PM_EVENTS	"/tmp/bpf_userspace_pm_events"
>  #define WITH_DATA	true
>  #define WITHOUT_DATA	false
>  
> @@ -57,6 +58,14 @@
>  #endif
>  #define MPTCP_SCHED_NAME_MAX	16
>  
> +enum mptcp_pm_type {
> +	MPTCP_PM_TYPE_KERNEL = 0,
> +	MPTCP_PM_TYPE_USERSPACE,
> +
> +	__MPTCP_PM_TYPE_NR,
> +	__MPTCP_PM_TYPE_MAX = __MPTCP_PM_TYPE_NR - 1,
> +};
> +
>  static const unsigned int total_bytes = 10 * 1024 * 1024;
>  static int duration;
>  
> @@ -252,6 +261,19 @@ static void send_byte(int fd)
>  	ASSERT_EQ(write(fd, &b, sizeof(b)), 1, "send single byte");
>  }
>  
> +static int recv_byte(int fd)
> +{
> +	char buf[1];
> +	ssize_t n;
> +
> +	n = recv(fd, buf, sizeof(buf), 0);
> +	if (CHECK(n <= 0, "recv_byte", "recv")) {
> +		log_err("failed/partial recv");
> +		return -1;
> +	}
> +	return 0;
> +}
> +
>  static int verify_mptcpify(int server_fd, int client_fd)
>  {
>  	struct __mptcp_info info;
> @@ -567,6 +589,196 @@ static void test_iters_subflow(void)
>  	close(cgroup_fd);
>  }
>  
> +static int userspace_pm_init(enum mptcp_pm_type pm_type)
> +{
> +	if (address_init())
> +		goto fail;
> +
> +	SYS(fail, "ip netns exec %s sysctl -qw
> net.mptcp.pm_type=%u",
> +	    NS_TEST, pm_type);
> +	SYS(fail, "ip netns exec %s %s limits 4 4",
> +	    NS_TEST, PM_CTL);
> +	SYS(fail, "ip netns exec %s %s events >> %s 2>&1 &",
> +	    NS_TEST, PM_CTL, PM_EVENTS);
> +
> +	return 0;
> +fail:
> +	return -1;
> +}
> +
> +static void userspace_pm_cleanup(void)
> +{
> +	SYS_NOFAIL("ip netns exec %s killall %s > /dev/null 2>&1",
> +		   NS_TEST, PM_CTL);
> +	SYS_NOFAIL("ip netns exec %s rm -rf %s", NS_TEST,
> PM_EVENTS);
> +}
> +
> +static int userspace_pm_get_events_line(char *type, char *line)
> +{
> +	char buf[BUFSIZ], *str;
> +	size_t len;
> +	int fd;
> +
> +	fd = open(PM_EVENTS, O_RDONLY);
> +	if (fd < 0) {
> +		log_err("failed to open pm events\n");
> +		return -1;
> +	}
> +
> +	len = read(fd, buf, sizeof(buf));
> +	close(fd);
> +	if (len <= 0) {
> +		log_err("failed to read pm events\n");
> +		return -1;
> +	}
> +
> +	str = strstr(buf, type);
> +	if (!str) {
> +		log_err("failed to get type %s pm event\n", type);
> +		return -1;
> +	}
> +
> +	strcpy(line, str);
> +	return 0;
> +}
> +
> +static int userspace_pm_get_token(int fd)
> +{
> +	char line[1024], *str;
> +	__u32 token;
> +	int i;
> +
> +	/* Wait max 2 sec for the connection to be established */
> +	for (i = 0; i < 10; i++) {
> +		usleep(200000); /* 0.2s */
> +		send_byte(fd);
> +
> +		sync();
> +		if (userspace_pm_get_events_line("type:2", line))
> +			continue;
> +		str = strstr(line, "token");
> +		if (!str)
> +			continue;
> +		if (sscanf(str, "token:%u,", &token) != 1)
> +			continue;
> +		return token;
> +	}
> +
> +	return 0;
> +}
> +
> +static int userspace_pm_add_subflow(__u32 token, char *addr, __u8
> id)
> +{
> +	bool ipv6 = strstr(addr, ":");
> +	char line[1024], *str;
> +	__u32 sport, dport;
> +
> +	if (userspace_pm_get_events_line("type:2", line))
> +		return -1;
> +
> +	str = strstr(line, "sport");
> +	if (!str || sscanf(str, "sport:%u,dport:%u,", &sport,
> &dport) != 2) {
> +		log_err("add_subflow error, str=%s\n", str);
> +		return -1;
> +	}
> +
> +	str = ipv6 ? (strstr(addr, ".") ? "::ffff:"ADDR_1 : ADDR6_1)
> : ADDR_1;
> +	SYS_NOFAIL("ip netns exec %s %s csf lip %s lid %u rip %s
> rport %u token %u",
> +		   NS_TEST, PM_CTL, addr, id, str, dport, token);
> +
> +	return 0;
> +}
> +
> +static void run_iters_address(void)
> +{
> +	int server_fd, client_fd, accept_fd;
> +	int is_mptcp, err;
> +	socklen_t len;
> +	__u32 token;
> +
> +	server_fd = start_mptcp_server(AF_INET, ADDR_1, PORT_1, 0);
> +	if (!ASSERT_OK_FD(server_fd, "start_mptcp_server"))
> +		return;
> +
> +	client_fd = connect_to_fd(server_fd, 0);
> +	if (!ASSERT_OK_FD(client_fd, "connect_to_fd"))
> +		goto close_server;
> +
> +	accept_fd = accept(server_fd, NULL, NULL);
> +	if (!ASSERT_OK_FD(accept_fd, "accept"))
> +		goto close_client;
> +
> +	token = userspace_pm_get_token(client_fd);
> +	if (!token)
> +		goto close_client;
> +	recv_byte(accept_fd);
> +	usleep(200000); /* 0.2s */
> +
> +	err = userspace_pm_add_subflow(token, ADDR_2, 10);
> +	err = err ?: userspace_pm_add_subflow(token, ADDR_3, 20);
> +	err = err ?: userspace_pm_add_subflow(token, ADDR_4, 30);
> +	if (!ASSERT_OK(err, "userspace_pm_add_subflow"))
> +		goto close_accept;
> +
> +	send_byte(accept_fd);
> +	recv_byte(client_fd);
> +
> +	len = sizeof(is_mptcp);
> +	/* mainly to trigger the BPF program */
> +	err = getsockopt(client_fd, SOL_TCP, TCP_IS_MPTCP,
> &is_mptcp, &len);
> +	if (ASSERT_OK(err, "getsockopt(client_fd, TCP_IS_MPTCP)"))
> +		ASSERT_EQ(is_mptcp, 1, "is_mptcp");
> +
> +close_accept:
> +	close(accept_fd);
> +close_client:
> +	close(client_fd);
> +close_server:
> +	close(server_fd);
> +}
> +
> +static void test_iters_address(void)
> +{
> +	struct mptcp_bpf_iters *skel;
> +	struct netns_obj *netns;
> +	int cgroup_fd;
> +	int err;
> +
> +	cgroup_fd = test__join_cgroup("/iters_address");
> +	if (!ASSERT_OK_FD(cgroup_fd, "join_cgroup: iters_address"))
> +		return;
> +
> +	skel = mptcp_bpf_iters__open_and_load();
> +	if (!ASSERT_OK_PTR(skel, "skel_open_load: iters_address"))
> +		goto close_cgroup;
> +
> +	skel->links.iters_address = bpf_program__attach_cgroup(skel-
> >progs.iters_address,
> +							      
> cgroup_fd);
> +	if (!ASSERT_OK_PTR(skel->links.iters_address, "attach
> getsockopt"))
> +		goto skel_destroy;
> +
> +	netns = netns_new(NS_TEST, true);
> +	if (!ASSERT_OK_PTR(netns, "netns_new"))
> +		goto skel_destroy;
> +
> +	err = userspace_pm_init(MPTCP_PM_TYPE_USERSPACE);
> +	if (!ASSERT_OK(err, "userspace_pm_init: iters_address"))
> +		goto close_netns;
> +
> +	run_iters_address();
> +
> +	/* 10 + 20 + 30 = 60 */
> +	ASSERT_EQ(skel->bss->ids, 60, "address ids");
> +
> +	userspace_pm_cleanup();
> +close_netns:
> +	netns_free(netns);
> +skel_destroy:
> +	mptcp_bpf_iters__destroy(skel);
> +close_cgroup:
> +	close(cgroup_fd);
> +}
> +
>  static struct netns_obj *sched_init(char *flags, char *sched)
>  {
>  	struct netns_obj *netns;
> @@ -750,6 +962,8 @@ void test_mptcp(void)
>  		test_subflow();
>  	if (test__start_subtest("iters_subflow"))
>  		test_iters_subflow();
> +	if (test__start_subtest("iters_address"))
> +		test_iters_address();
>  	if (test__start_subtest("default"))
>  		test_default();
>  	if (test__start_subtest("first"))
> diff --git a/tools/testing/selftests/bpf/progs/mptcp_bpf.h
> b/tools/testing/selftests/bpf/progs/mptcp_bpf.h
> index b1f6e1fb467e..5e29ac93d823 100644
> --- a/tools/testing/selftests/bpf/progs/mptcp_bpf.h
> +++ b/tools/testing/selftests/bpf/progs/mptcp_bpf.h
> @@ -51,6 +51,11 @@ bpf_mptcp_subflow_ctx(const struct sock *sk)
> __ksym;
>  extern struct sock *
>  bpf_mptcp_subflow_tcp_sock(const struct mptcp_subflow_context
> *subflow) __ksym;
>  
> +extern void bpf_spin_lock_bh(spinlock_t *lock) __ksym;
> +extern void bpf_spin_unlock_bh(spinlock_t *lock) __ksym;
> +
> +extern bool bpf_ipv4_is_private_10(__be32 addr) __ksym;
> +
>  extern void mptcp_subflow_set_scheduled(struct mptcp_subflow_context
> *subflow,
>  					bool scheduled) __ksym;
>  
> diff --git a/tools/testing/selftests/bpf/progs/mptcp_bpf_iters.c
> b/tools/testing/selftests/bpf/progs/mptcp_bpf_iters.c
> index fd5691a4073b..e11339641e8d 100644
> --- a/tools/testing/selftests/bpf/progs/mptcp_bpf_iters.c
> +++ b/tools/testing/selftests/bpf/progs/mptcp_bpf_iters.c
> @@ -61,3 +61,41 @@ int iters_subflow(struct bpf_sockopt *ctx)
>  	bpf_mptcp_sock_release(msk);
>  	return 1;
>  }
> +
> +SEC("cgroup/getsockopt")
> +int iters_address(struct bpf_sockopt *ctx)
> +{
> +	struct mptcp_pm_addr_entry *entry;
> +	struct bpf_sock *sk = ctx->sk;
> +	struct mptcp_sock *msk;
> +	int local_ids = 0;
> +
> +	if (ctx->level != SOL_TCP || ctx->optname != TCP_IS_MPTCP)
> +		return 1;
> +
> +	msk = bpf_skc_to_mptcp_sock(sk);
> +	if (!msk || msk->pm.server_side)
> +		return 1;
> +
> +	msk = bpf_mptcp_sock_acquire(msk);
> +	if (!msk)
> +		return 1;
> +	bpf_spin_lock_bh(&msk->pm.lock);
> +	bpf_for_each(mptcp_userspace_pm_addr, entry, msk) {
> +		/* Here MPTCP-specific path manager kfunc can be
> called:
> +		 * this test is not doing anything really useful,
> only to
> +		 * verify the iteration works.
> +		 */
> +
> +		if (!bpf_ipv4_is_private_10(entry-
> >addr.addr.s_addr))
> +			break;
> +
> +		local_ids += entry->addr.id;
> +	}
> +	bpf_spin_unlock_bh(&msk->pm.lock);
> +	bpf_mptcp_sock_release(msk);
> +
> +	ids = local_ids;
> +
> +	return 1;
> +}

Patch

diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
index 2ab3f0063c0f..01201917a446 100644
--- a/tools/testing/selftests/bpf/bpf_experimental.h
+++ b/tools/testing/selftests/bpf/bpf_experimental.h
@@ -583,6 +583,14 @@  bpf_iter_mptcp_subflow_next(struct bpf_iter_mptcp_subflow *it) __weak __ksym;
 extern void
 bpf_iter_mptcp_subflow_destroy(struct bpf_iter_mptcp_subflow *it) __weak __ksym;
 
+struct bpf_iter_mptcp_userspace_pm_addr;
+extern int bpf_iter_mptcp_userspace_pm_addr_new(struct bpf_iter_mptcp_userspace_pm_addr *it,
+						struct mptcp_sock *msk) __weak __ksym;
+extern struct mptcp_pm_addr_entry *
+bpf_iter_mptcp_userspace_pm_addr_next(struct bpf_iter_mptcp_userspace_pm_addr *it) __weak __ksym;
+extern void
+bpf_iter_mptcp_userspace_pm_addr_destroy(struct bpf_iter_mptcp_userspace_pm_addr *it) __weak __ksym;
+
 extern int bpf_wq_init(struct bpf_wq *wq, void *p__map, unsigned int flags) __weak __ksym;
 extern int bpf_wq_start(struct bpf_wq *wq, unsigned int flags) __weak __ksym;
 extern int bpf_wq_set_callback_impl(struct bpf_wq *wq,
diff --git a/tools/testing/selftests/bpf/prog_tests/mptcp.c b/tools/testing/selftests/bpf/prog_tests/mptcp.c
index 5cab0aa8fb27..d50dc332f545 100644
--- a/tools/testing/selftests/bpf/prog_tests/mptcp.c
+++ b/tools/testing/selftests/bpf/prog_tests/mptcp.c
@@ -29,6 +29,7 @@ 
 #define ADDR6_4	"dead:beef:4::1"
 #define PORT_1	10001
 #define PM_CTL		"./mptcp_pm_nl_ctl"
+#define PM_EVENTS	"/tmp/bpf_userspace_pm_events"
 #define WITH_DATA	true
 #define WITHOUT_DATA	false
 
@@ -57,6 +58,14 @@ 
 #endif
 #define MPTCP_SCHED_NAME_MAX	16
 
+enum mptcp_pm_type {
+	MPTCP_PM_TYPE_KERNEL = 0,
+	MPTCP_PM_TYPE_USERSPACE,
+
+	__MPTCP_PM_TYPE_NR,
+	__MPTCP_PM_TYPE_MAX = __MPTCP_PM_TYPE_NR - 1,
+};
+
 static const unsigned int total_bytes = 10 * 1024 * 1024;
 static int duration;
 
@@ -252,6 +261,19 @@  static void send_byte(int fd)
 	ASSERT_EQ(write(fd, &b, sizeof(b)), 1, "send single byte");
 }
 
+static int recv_byte(int fd)
+{
+	char buf[1];
+	ssize_t n;
+
+	n = recv(fd, buf, sizeof(buf), 0);
+	if (CHECK(n <= 0, "recv_byte", "recv")) {
+		log_err("failed/partial recv");
+		return -1;
+	}
+	return 0;
+}
+
 static int verify_mptcpify(int server_fd, int client_fd)
 {
 	struct __mptcp_info info;
@@ -567,6 +589,196 @@  static void test_iters_subflow(void)
 	close(cgroup_fd);
 }
 
+static int userspace_pm_init(enum mptcp_pm_type pm_type)
+{
+	if (address_init())
+		goto fail;
+
+	SYS(fail, "ip netns exec %s sysctl -qw net.mptcp.pm_type=%u",
+	    NS_TEST, pm_type);
+	SYS(fail, "ip netns exec %s %s limits 4 4",
+	    NS_TEST, PM_CTL);
+	SYS(fail, "ip netns exec %s %s events >> %s 2>&1 &",
+	    NS_TEST, PM_CTL, PM_EVENTS);
+
+	return 0;
+fail:
+	return -1;
+}
+
+static void userspace_pm_cleanup(void)
+{
+	SYS_NOFAIL("ip netns exec %s killall %s > /dev/null 2>&1",
+		   NS_TEST, PM_CTL);
+	SYS_NOFAIL("ip netns exec %s rm -rf %s", NS_TEST, PM_EVENTS);
+}
+
+static int userspace_pm_get_events_line(char *type, char *line)
+{
+	char buf[BUFSIZ], *str;
+	size_t len;
+	int fd;
+
+	fd = open(PM_EVENTS, O_RDONLY);
+	if (fd < 0) {
+		log_err("failed to open pm events\n");
+		return -1;
+	}
+
+	len = read(fd, buf, sizeof(buf));
+	close(fd);
+	if (len <= 0) {
+		log_err("failed to read pm events\n");
+		return -1;
+	}
+
+	str = strstr(buf, type);
+	if (!str) {
+		log_err("failed to get type %s pm event\n", type);
+		return -1;
+	}
+
+	strcpy(line, str);
+	return 0;
+}
+
+static int userspace_pm_get_token(int fd)
+{
+	char line[1024], *str;
+	__u32 token;
+	int i;
+
+	/* Wait max 2 sec for the connection to be established */
+	for (i = 0; i < 10; i++) {
+		usleep(200000); /* 0.2s */
+		send_byte(fd);
+
+		sync();
+		if (userspace_pm_get_events_line("type:2", line))
+			continue;
+		str = strstr(line, "token");
+		if (!str)
+			continue;
+		if (sscanf(str, "token:%u,", &token) != 1)
+			continue;
+		return token;
+	}
+
+	return 0;
+}
+
+static int userspace_pm_add_subflow(__u32 token, char *addr, __u8 id)
+{
+	bool ipv6 = strstr(addr, ":");
+	char line[1024], *str;
+	__u32 sport, dport;
+
+	if (userspace_pm_get_events_line("type:2", line))
+		return -1;
+
+	str = strstr(line, "sport");
+	if (!str || sscanf(str, "sport:%u,dport:%u,", &sport, &dport) != 2) {
+		log_err("add_subflow error, str=%s\n", str);
+		return -1;
+	}
+
+	str = ipv6 ? (strstr(addr, ".") ? "::ffff:"ADDR_1 : ADDR6_1) : ADDR_1;
+	SYS_NOFAIL("ip netns exec %s %s csf lip %s lid %u rip %s rport %u token %u",
+		   NS_TEST, PM_CTL, addr, id, str, dport, token);
+
+	return 0;
+}
+
+static void run_iters_address(void)
+{
+	int server_fd, client_fd, accept_fd;
+	int is_mptcp, err;
+	socklen_t len;
+	__u32 token;
+
+	server_fd = start_mptcp_server(AF_INET, ADDR_1, PORT_1, 0);
+	if (!ASSERT_OK_FD(server_fd, "start_mptcp_server"))
+		return;
+
+	client_fd = connect_to_fd(server_fd, 0);
+	if (!ASSERT_OK_FD(client_fd, "connect_to_fd"))
+		goto close_server;
+
+	accept_fd = accept(server_fd, NULL, NULL);
+	if (!ASSERT_OK_FD(accept_fd, "accept"))
+		goto close_client;
+
+	token = userspace_pm_get_token(client_fd);
+	if (!token)
+		goto close_client;
+	recv_byte(accept_fd);
+	usleep(200000); /* 0.2s */
+
+	err = userspace_pm_add_subflow(token, ADDR_2, 10);
+	err = err ?: userspace_pm_add_subflow(token, ADDR_3, 20);
+	err = err ?: userspace_pm_add_subflow(token, ADDR_4, 30);
+	if (!ASSERT_OK(err, "userspace_pm_add_subflow"))
+		goto close_accept;
+
+	send_byte(accept_fd);
+	recv_byte(client_fd);
+
+	len = sizeof(is_mptcp);
+	/* mainly to trigger the BPF program */
+	err = getsockopt(client_fd, SOL_TCP, TCP_IS_MPTCP, &is_mptcp, &len);
+	if (ASSERT_OK(err, "getsockopt(client_fd, TCP_IS_MPTCP)"))
+		ASSERT_EQ(is_mptcp, 1, "is_mptcp");
+
+close_accept:
+	close(accept_fd);
+close_client:
+	close(client_fd);
+close_server:
+	close(server_fd);
+}
+
+static void test_iters_address(void)
+{
+	struct mptcp_bpf_iters *skel;
+	struct netns_obj *netns;
+	int cgroup_fd;
+	int err;
+
+	cgroup_fd = test__join_cgroup("/iters_address");
+	if (!ASSERT_OK_FD(cgroup_fd, "join_cgroup: iters_address"))
+		return;
+
+	skel = mptcp_bpf_iters__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_open_load: iters_address"))
+		goto close_cgroup;
+
+	skel->links.iters_address = bpf_program__attach_cgroup(skel->progs.iters_address,
+							       cgroup_fd);
+	if (!ASSERT_OK_PTR(skel->links.iters_address, "attach getsockopt"))
+		goto skel_destroy;
+
+	netns = netns_new(NS_TEST, true);
+	if (!ASSERT_OK_PTR(netns, "netns_new"))
+		goto skel_destroy;
+
+	err = userspace_pm_init(MPTCP_PM_TYPE_USERSPACE);
+	if (!ASSERT_OK(err, "userspace_pm_init: iters_address"))
+		goto close_netns;
+
+	run_iters_address();
+
+	/* 10 + 20 + 30 = 60 */
+	ASSERT_EQ(skel->bss->ids, 60, "address ids");
+
+	userspace_pm_cleanup();
+close_netns:
+	netns_free(netns);
+skel_destroy:
+	mptcp_bpf_iters__destroy(skel);
+close_cgroup:
+	close(cgroup_fd);
+}
+
 static struct netns_obj *sched_init(char *flags, char *sched)
 {
 	struct netns_obj *netns;
@@ -750,6 +962,8 @@  void test_mptcp(void)
 		test_subflow();
 	if (test__start_subtest("iters_subflow"))
 		test_iters_subflow();
+	if (test__start_subtest("iters_address"))
+		test_iters_address();
 	if (test__start_subtest("default"))
 		test_default();
 	if (test__start_subtest("first"))
diff --git a/tools/testing/selftests/bpf/progs/mptcp_bpf.h b/tools/testing/selftests/bpf/progs/mptcp_bpf.h
index b1f6e1fb467e..5e29ac93d823 100644
--- a/tools/testing/selftests/bpf/progs/mptcp_bpf.h
+++ b/tools/testing/selftests/bpf/progs/mptcp_bpf.h
@@ -51,6 +51,11 @@  bpf_mptcp_subflow_ctx(const struct sock *sk) __ksym;
 extern struct sock *
 bpf_mptcp_subflow_tcp_sock(const struct mptcp_subflow_context *subflow) __ksym;
 
+extern void bpf_spin_lock_bh(spinlock_t *lock) __ksym;
+extern void bpf_spin_unlock_bh(spinlock_t *lock) __ksym;
+
+extern bool bpf_ipv4_is_private_10(__be32 addr) __ksym;
+
 extern void mptcp_subflow_set_scheduled(struct mptcp_subflow_context *subflow,
 					bool scheduled) __ksym;
 
diff --git a/tools/testing/selftests/bpf/progs/mptcp_bpf_iters.c b/tools/testing/selftests/bpf/progs/mptcp_bpf_iters.c
index fd5691a4073b..e11339641e8d 100644
--- a/tools/testing/selftests/bpf/progs/mptcp_bpf_iters.c
+++ b/tools/testing/selftests/bpf/progs/mptcp_bpf_iters.c
@@ -61,3 +61,41 @@  int iters_subflow(struct bpf_sockopt *ctx)
 	bpf_mptcp_sock_release(msk);
 	return 1;
 }
+
+SEC("cgroup/getsockopt")
+int iters_address(struct bpf_sockopt *ctx)
+{
+	struct mptcp_pm_addr_entry *entry;
+	struct bpf_sock *sk = ctx->sk;
+	struct mptcp_sock *msk;
+	int local_ids = 0;
+
+	if (ctx->level != SOL_TCP || ctx->optname != TCP_IS_MPTCP)
+		return 1;
+
+	msk = bpf_skc_to_mptcp_sock(sk);
+	if (!msk || msk->pm.server_side)
+		return 1;
+
+	msk = bpf_mptcp_sock_acquire(msk);
+	if (!msk)
+		return 1;
+	bpf_spin_lock_bh(&msk->pm.lock);
+	bpf_for_each(mptcp_userspace_pm_addr, entry, msk) {
+		/* Here MPTCP-specific path manager kfunc can be called:
+		 * this test is not doing anything really useful, only to
+		 * verify the iteration works.
+		 */
+
+		if (!bpf_ipv4_is_private_10(entry->addr.addr.s_addr))
+			break;
+
+		local_ids += entry->addr.id;
+	}
+	bpf_spin_unlock_bh(&msk->pm.lock);
+	bpf_mptcp_sock_release(msk);
+
+	ids = local_ids;
+
+	return 1;
+}