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From: Geliang Tang <geliang@kernel.org>
To: mptcp@lists.linux.dev
Cc: Geliang Tang <tanggeliang@kylinos.cn>,
Mat Martineau <martineau@kernel.org>
Subject: [PATCH mptcp-next v3 1/2] mptcp: add bpf_iter_task for mptcp_sock
Date: Mon, 10 Mar 2025 11:30:09 +0800
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<e04cc2fa5f500097ac7d95afb94f68d0d8dc0057.1741577149.git.tanggeliang@kylinos.cn>
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From: Geliang Tang <tanggeliang@kylinos.cn>
To make sure the mptcp_subflow bpf_iter is running in the
MPTCP context. This patch adds a simplified version of tracking
for it:
1. Add a 'struct task_struct *bpf_iter_task' field to struct
mptcp_sock.
2. Do a WRITE_ONCE(msk->bpf_iter_task, current) before calling
a MPTCP BPF hook, and WRITE_ONCE(msk->bpf_iter_task, NULL) after
the hook returns.
3. In bpf_iter_mptcp_subflow_new(), check
"READ_ONCE(msk->bpf_scheduler_task) =3D=3D current"
to confirm the correct task, return -EINVAL if it doesn't match.
Also creates helpers for setting, clearing and checking that value.
Suggested-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
net/mptcp/bpf.c | 2 ++
net/mptcp/protocol.c | 1 +
net/mptcp/protocol.h | 20 ++++++++++++++++++++
net/mptcp/sched.c | 15 +++++++++++----
4 files changed, 34 insertions(+), 4 deletions(-)
diff --git a/net/mptcp/bpf.c b/net/mptcp/bpf.c
index c0da9ac077e4..0a78604742c7 100644
--- a/net/mptcp/bpf.c
+++ b/net/mptcp/bpf.c
@@ -261,6 +261,8 @@ bpf_iter_mptcp_subflow_new(struct bpf_iter_mptcp_subflo=
w *it,
return -EINVAL;
=20
msk =3D mptcp_sk(sk);
+ if (!mptcp_check_bpf_iter_task(msk))
+ return -EINVAL;
=20
msk_owned_by_me(msk);
=20
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 01157ad2e2dc..d98e48ce8cd8 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2729,6 +2729,7 @@ static void __mptcp_init_sock(struct sock *sk)
inet_csk(sk)->icsk_sync_mss =3D mptcp_sync_mss;
WRITE_ONCE(msk->csum_enabled, mptcp_is_checksum_enabled(sock_net(sk)));
WRITE_ONCE(msk->allow_infinite_fallback, true);
+ mptcp_clear_bpf_iter_task(msk);
msk->recovery =3D false;
msk->subflow_id =3D 1;
msk->last_data_sent =3D tcp_jiffies32;
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 3492b256ecba..1c6958d64291 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -334,6 +334,7 @@ struct mptcp_sock {
*/
struct mptcp_pm_data pm;
struct mptcp_sched_ops *sched;
+ struct task_struct *bpf_iter_task;
struct {
u32 space; /* bytes copied in last measurement window */
u32 copied; /* bytes copied in this measurement window */
@@ -1291,4 +1292,23 @@ mptcp_token_join_cookie_init_state(struct mptcp_subf=
low_request_sock *subflow_re
static inline void mptcp_join_cookie_init(void) {}
#endif
=20
+static inline void mptcp_set_bpf_iter_task(struct mptcp_sock *msk)
+{
+ WRITE_ONCE(msk->bpf_iter_task, current);
+}
+
+static inline void mptcp_clear_bpf_iter_task(struct mptcp_sock *msk)
+{
+ WRITE_ONCE(msk->bpf_iter_task, NULL);
+}
+
+static inline bool mptcp_check_bpf_iter_task(struct mptcp_sock *msk)
+{
+ struct task_struct *task =3D READ_ONCE(msk->bpf_iter_task);
+
+ if (task && task =3D=3D current)
+ return true;
+ return false;
+}
+
#endif /* __MPTCP_PROTOCOL_H */
diff --git a/net/mptcp/sched.c b/net/mptcp/sched.c
index f09f7eb1d63f..161398f8960c 100644
--- a/net/mptcp/sched.c
+++ b/net/mptcp/sched.c
@@ -155,6 +155,7 @@ void mptcp_subflow_set_scheduled(struct mptcp_subflow_c=
ontext *subflow,
int mptcp_sched_get_send(struct mptcp_sock *msk)
{
struct mptcp_subflow_context *subflow;
+ int ret;
=20
msk_owned_by_me(msk);
=20
@@ -176,12 +177,16 @@ int mptcp_sched_get_send(struct mptcp_sock *msk)
=20
if (msk->sched =3D=3D &mptcp_sched_default || !msk->sched)
return mptcp_sched_default_get_send(msk);
- return msk->sched->get_send(msk);
+ mptcp_set_bpf_iter_task(msk);
+ ret =3D msk->sched->get_send(msk);
+ mptcp_clear_bpf_iter_task(msk);
+ return ret;
}
=20
int mptcp_sched_get_retrans(struct mptcp_sock *msk)
{
struct mptcp_subflow_context *subflow;
+ int ret;
=20
msk_owned_by_me(msk);
=20
@@ -196,7 +201,9 @@ int mptcp_sched_get_retrans(struct mptcp_sock *msk)
=20
if (msk->sched =3D=3D &mptcp_sched_default || !msk->sched)
return mptcp_sched_default_get_retrans(msk);
- if (msk->sched->get_retrans)
- return msk->sched->get_retrans(msk);
- return msk->sched->get_send(msk);
+ mptcp_set_bpf_iter_task(msk);
+ ret =3D msk->sched->get_retrans ? msk->sched->get_retrans(msk) :
+ msk->sched->get_send(msk);
+ mptcp_clear_bpf_iter_task(msk);
+ return ret;
}
--=20
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