diff mbox series

[mptcp-net,v2,1/4] mptcp: fix lockless access in subflow ULP diag

Message ID 96f99278110c7ebd0ac401094b367f9bbdf5240f.1707418323.git.pabeni@redhat.com (mailing list archive)
State Accepted, archived
Commit ce4271cba41b2bec0ade2a3f18d86a403966edbe
Delegated to: Matthieu Baerts
Headers show
Series mptcp: fix duplicate subflow creation | expand

Checks

Context Check Description
matttbe/build success Build and static analysis OK
matttbe/checkpatch success total: 0 errors, 0 warnings, 0 checks, 49 lines checked
matttbe/KVM_Validation__normal success Success! ✅
matttbe/KVM_Validation__debug__except_selftest_mptcp_join_ success Success! ✅
matttbe/KVM_Validation__debug__only_selftest_mptcp_join_ success Success! ✅

Commit Message

Paolo Abeni Feb. 8, 2024, 8:42 p.m. UTC 
Since the introduction of the subflow ULP diag interface, the
dump callback accessed all the subflow data with lockless.

We need either to annotate all the read and write operation accordingly,
or acquire the subflow socket lock. Let's do latter, even if slower, to
avoid a diffstat havoc.

Fixes: 5147dfb50832 ("mptcp: allow dumping subflow context to userspace")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
note: tls ulp diag has likely the same issue.
---
 include/net/tcp.h  | 2 +-
 net/mptcp/diag.c   | 6 +++++-
 net/tls/tls_main.c | 2 +-
 3 files changed, 7 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 58e65af74ad1..33bf92dff0af 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2551,7 +2551,7 @@  struct tcp_ulp_ops {
 	/* cleanup ulp */
 	void (*release)(struct sock *sk);
 	/* diagnostic */
-	int (*get_info)(const struct sock *sk, struct sk_buff *skb);
+	int (*get_info)(struct sock *sk, struct sk_buff *skb);
 	size_t (*get_info_size)(const struct sock *sk);
 	/* clone ulp */
 	void (*clone)(const struct request_sock *req, struct sock *newsk,
diff --git a/net/mptcp/diag.c b/net/mptcp/diag.c
index a536586742f2..e57c5f47f035 100644
--- a/net/mptcp/diag.c
+++ b/net/mptcp/diag.c
@@ -13,17 +13,19 @@ 
 #include <uapi/linux/mptcp.h>
 #include "protocol.h"
 
-static int subflow_get_info(const struct sock *sk, struct sk_buff *skb)
+static int subflow_get_info(struct sock *sk, struct sk_buff *skb)
 {
 	struct mptcp_subflow_context *sf;
 	struct nlattr *start;
 	u32 flags = 0;
+	bool slow;
 	int err;
 
 	start = nla_nest_start_noflag(skb, INET_ULP_INFO_MPTCP);
 	if (!start)
 		return -EMSGSIZE;
 
+	slow = lock_sock_fast(sk);
 	rcu_read_lock();
 	sf = rcu_dereference(inet_csk(sk)->icsk_ulp_data);
 	if (!sf) {
@@ -69,11 +71,13 @@  static int subflow_get_info(const struct sock *sk, struct sk_buff *skb)
 	}
 
 	rcu_read_unlock();
+	unlock_sock_fast(sk, slow);
 	nla_nest_end(skb, start);
 	return 0;
 
 nla_failure:
 	rcu_read_unlock();
+	unlock_sock_fast(sk, slow);
 	nla_nest_cancel(skb, start);
 	return err;
 }
diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index 1c2c6800949d..b4674f03d71a 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -1003,7 +1003,7 @@  static u16 tls_user_config(struct tls_context *ctx, bool tx)
 	return 0;
 }
 
-static int tls_get_info(const struct sock *sk, struct sk_buff *skb)
+static int tls_get_info(struct sock *sk, struct sk_buff *skb)
 {
 	u16 version, cipher_type;
 	struct tls_context *ctx;