diff mbox series

[net,1/3] mptcp: move subflow cleanup in mptcp_destroy_common()

Message ID 20220805002127.88430-2-mathew.j.martineau@linux.intel.com (mailing list archive)
State Accepted
Commit c0bf3c6aa444a5ef44acc57ef6cfa53fd4fc1c9b
Delegated to: Netdev Maintainers
Headers show
Series mptcp: Fixes for mptcp cleanup/close and a selftest | expand

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Context Check Description
netdev/tree_selection success Clearly marked for net, async
netdev/fixes_present success Fixes tag present in non-next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 5 this patch: 5
netdev/cc_maintainers success CCed 9 of 9 maintainers
netdev/build_clang success Errors and warnings before: 7 this patch: 7
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes fail Problems with Fixes tag: 1
netdev/build_allmodconfig_warn success Errors and warnings before: 5 this patch: 5
netdev/checkpatch warning WARNING: line length of 83 exceeds 80 columns WARNING: line length of 87 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Mat Martineau Aug. 5, 2022, 12:21 a.m. UTC 
From: Paolo Abeni <pabeni@redhat.com>

If the mptcp socket creation fails due to a CGROUP_INET_SOCK_CREATE
eBPF program, the MPTCP protocol ends-up leaking all the subflows:
the related cleanup happens in __mptcp_destroy_sock() that is not
invoked in such code path.

Address the issue moving the subflow sockets cleanup in the
mptcp_destroy_common() helper, which is invoked in every msk cleanup
path.

Additionally get rid of the intermediate list_splice_init step, which
is an unneeded relic from the past.

The issue is present since before the reported root cause commit, but
any attempt to backport the fix before that hash will require a complete
rewrite.

Fixes: e16163b6e2 ("mptcp: refactor shutdown and close")
Reported-by: Nguyen Dinh Phi <phind.uet@gmail.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Co-developed-by: Nguyen Dinh Phi <phind.uet@gmail.com>
Signed-off-by: Nguyen Dinh Phi <phind.uet@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 net/mptcp/protocol.c | 39 +++++++++++++++------------------------
 net/mptcp/protocol.h |  2 +-
 net/mptcp/subflow.c  |  3 ++-
 3 files changed, 18 insertions(+), 26 deletions(-)
diff mbox series

Patch

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index a3f1c1461874..07fcc86e1fc9 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2769,30 +2769,16 @@  static void __mptcp_wr_shutdown(struct sock *sk)
 
 static void __mptcp_destroy_sock(struct sock *sk)
 {
-	struct mptcp_subflow_context *subflow, *tmp;
 	struct mptcp_sock *msk = mptcp_sk(sk);
-	LIST_HEAD(conn_list);
 
 	pr_debug("msk=%p", msk);
 
 	might_sleep();
 
-	/* join list will be eventually flushed (with rst) at sock lock release time*/
-	list_splice_init(&msk->conn_list, &conn_list);
-
 	mptcp_stop_timer(sk);
 	sk_stop_timer(sk, &sk->sk_timer);
 	msk->pm.status = 0;
 
-	/* clears msk->subflow, allowing the following loop to close
-	 * even the initial subflow
-	 */
-	mptcp_dispose_initial_subflow(msk);
-	list_for_each_entry_safe(subflow, tmp, &conn_list, node) {
-		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
-		__mptcp_close_ssk(sk, ssk, subflow, 0);
-	}
-
 	sk->sk_prot->destroy(sk);
 
 	WARN_ON_ONCE(msk->rmem_fwd_alloc);
@@ -2884,24 +2870,20 @@  static void mptcp_copy_inaddrs(struct sock *msk, const struct sock *ssk)
 
 static int mptcp_disconnect(struct sock *sk, int flags)
 {
-	struct mptcp_subflow_context *subflow, *tmp;
 	struct mptcp_sock *msk = mptcp_sk(sk);
 
 	inet_sk_state_store(sk, TCP_CLOSE);
 
-	list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) {
-		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
-
-		__mptcp_close_ssk(sk, ssk, subflow, MPTCP_CF_FASTCLOSE);
-	}
-
 	mptcp_stop_timer(sk);
 	sk_stop_timer(sk, &sk->sk_timer);
 
 	if (mptcp_sk(sk)->token)
 		mptcp_event(MPTCP_EVENT_CLOSED, mptcp_sk(sk), NULL, GFP_KERNEL);
 
-	mptcp_destroy_common(msk);
+	/* msk->subflow is still intact, the following will not free the first
+	 * subflow
+	 */
+	mptcp_destroy_common(msk, MPTCP_CF_FASTCLOSE);
 	msk->last_snd = NULL;
 	WRITE_ONCE(msk->flags, 0);
 	msk->cb_flags = 0;
@@ -3051,12 +3033,17 @@  static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
 	return newsk;
 }
 
-void mptcp_destroy_common(struct mptcp_sock *msk)
+void mptcp_destroy_common(struct mptcp_sock *msk, unsigned int flags)
 {
+	struct mptcp_subflow_context *subflow, *tmp;
 	struct sock *sk = (struct sock *)msk;
 
 	__mptcp_clear_xmit(sk);
 
+	/* join list will be eventually flushed (with rst) at sock lock release time */
+	list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node)
+		__mptcp_close_ssk(sk, mptcp_subflow_tcp_sock(subflow), subflow, flags);
+
 	/* move to sk_receive_queue, sk_stream_kill_queues will purge it */
 	mptcp_data_lock(sk);
 	skb_queue_splice_tail_init(&msk->receive_queue, &sk->sk_receive_queue);
@@ -3078,7 +3065,11 @@  static void mptcp_destroy(struct sock *sk)
 {
 	struct mptcp_sock *msk = mptcp_sk(sk);
 
-	mptcp_destroy_common(msk);
+	/* clears msk->subflow, allowing the following to close
+	 * even the initial subflow
+	 */
+	mptcp_dispose_initial_subflow(msk);
+	mptcp_destroy_common(msk, 0);
 	sk_sockets_allocated_dec(sk);
 }
 
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 5d6043c16b09..40881a7df5d5 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -717,7 +717,7 @@  static inline void mptcp_write_space(struct sock *sk)
 	}
 }
 
-void mptcp_destroy_common(struct mptcp_sock *msk);
+void mptcp_destroy_common(struct mptcp_sock *msk, unsigned int flags);
 
 #define MPTCP_TOKEN_MAX_RETRIES	4
 
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 901c763dcdbb..c7d49fb6e7bd 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -621,7 +621,8 @@  static void mptcp_sock_destruct(struct sock *sk)
 		sock_orphan(sk);
 	}
 
-	mptcp_destroy_common(mptcp_sk(sk));
+	/* We don't need to clear msk->subflow, as it's still NULL at this point */
+	mptcp_destroy_common(mptcp_sk(sk), 0);
 	inet_sock_destruct(sk);
 }